Explosive emulsion compositions containing modified copolymers of isoprene, butadiene, and/or styrene

Abstract

The invention provides explosive emulsion compositions which include polymers of conjugated dienes and/or aryl-substituted olefins which have been hydrogenated, functionalized, and optionally modified. The explosive emulsion compositions include a copolymer of two different conjugated dienes. The polymers may be selectively hydrogenated to produce polymers which have highly controlled amounts of unsaturation, permitting highly selective functionalization.

Description

BACKGROUND OF THE INVENTION

[0001] This invention relates to explosive emulsion compositions containing functionalized diene polymers and methods of their use. More particularly, the invention relates to explosive emulsion compositions containing selectively hydrogenated copolymers prepared using conjugated dienes. The invention is additionally directed to explosive emulsion compositions containing chemically modified derivatives of the above polymers

[0002] Ammonium nitrate based explosives form the bulk of the world industrial explosive consumption. They are widely used in coal mining, metal and non-metal mining, quarrying and construction. Ammonium nitrate based industrial explosives have safety, storage stability and cost advantages over other industrial explosives, such as dynamite.

[0003] Sorbitan monooleate (SMO) is the historical emulsifier used by the explosive industry. Its lower cost and wide availability make it the emulsifier of choice for mild conditions and short sleep time (time of the explosive emulsion residence in a bore hole before blasting) applications.

[0004] Better performing emulsifiers were developed to make explosive emulsions which can be used in more severe applications. These more active emulsifiers were derived mostly from carboxylic acylating agents. Anhydride derivatives obtained by reacting an olefin, more specifically polyisobutene (PIB) with an unsaturated anhydride can be used, such as or after further modification, most of the time, by an amine or a hydroxylamine. Polyisobutene succinic anhydrides (PIBSA) and PIBSA reacted with amine are commercial examples of such emulsifiers used in the explosive industry.

[0005] A number of formulations are available to satisfy various applications. Ammonium nitrate based explosives are formulated as ammonium nitrate-fuel oil (ANFO) mixtures and water based compositions.

[0006] In general, ANFOs consist of 94% ammonium nitrate prills coated with 6% fuel oil. ANFOs are inexpensive, high energy and safe. They require a high percussion cap to detonate, making them safe to handle. The detonation sensitivity is, however, dependent on the particle size, the density, and porosity of the ammonium nitrate. Due to the hygroscopic nature of ammonium nitrate, ANFOs are very sensitive to water and their application in wet drill holes is, therefore, very limited.

[0007] To eliminate explosive sensitivity toward water, explosive emulsions and slurries were developed. In addition to water sensitivity, water-based explosives offer more detonation energy by unit volume and better initiability in small diameter charges.

[0008] Slurry explosives are water suspensions of mostly oxidizers mixed with smaller portions of sensitizers, gellants and stabilizers. They are more economical than the reverse micelle water-in-oil emulsion explosives.

[0009] Explosive emulsions are essentially composed of an oxidizer solution, a fuel (oil) and an emulsifier. To ensure detonability, small bubbles of gas are often incorporated using microspheres or gassing agents. The emulsion structure is composed of fine micro droplets of the oxidizer solution surrounded by a continuous oil phase. These micro droplets offer the advantage of intimate contact between fuel and oxidizer resulting in equal to better blasting performance than conventional water-based slurries.

[0010] Liquid, low molecular weight polymers, for example, functionally terminated polybutadiene liquid elastomers, are known and are used in various applications. These materials are generally highly unsaturated and are frequently used in polyurethane formulations. The preparation and application of hydroxy-terminated polybutadiene is detailed by J. C. Brosse et al. in Hydroxyl-terminated polymers obtained by free radical polymerization-Synthesis, characterization and applications, Advances in Polymer Science 81, Springer-Verlag, Berlin, Heidelberg, 1987, pp. 167-220.

[0011] Also, liquid, low molecular weight polymers possessing acrylate, carboxy- or mercapto-terminals are known. In addition to butadiene, it is known to utilize isoprene as the base monomer for the liquid, low molecular weight polymers. The liquid, low molecular weight polymers may contain additional monomers, such as styrene or acrylonitrile, for controlling compatibility in blends with polar materials, such as epoxy resins.

[0012] Also known in the prior art are pure hydrocarbon, non-functionalized liquid rubbers. These liquid, low molecular weight polymers contain varying degrees of unsaturation for utilization in vulcanization. Typical of highly unsaturated liquid, low molecular weight polymers is polybutadiene, e.g., that sold under the name RICON by Ricon Resins, Inc. A liquid polyisoprene which has been hydrogenated to saturate 90% of its original double bonds is marketed as LIR-290 by Kuraray Isoprene Chemical Co. Ltd. Still more highly saturated are liquid butyl rubbers available from Hardman Rubber Co., and Trilene, a liquid ethylene-propylene-diene rubber (EPDM) available from Crompton Chemical Co. The more highly saturated liquid elastomers exhibit good oxidation and ozone resistance properties.

[0013] Falk, Journal of Polymer Science: PART A-1, 9:2617-23 (1971), the entire contents of which are incorporated herein by reference, discloses a method of hydrogenating 1,4,-polybutadiene in the presence of 1,4-polyisoprene. More particularly, Falk discloses hydrogenation of the 1,4-polybutadiene block segment in the block copolymer of 1,4-polybutadiene-1,4-polyisoprene-1,4-polybutadiene and in random copolymers of butadiene and isoprene, with both polymerized monomers having predominantly 1,4-microstructure. Hydrogenation is conducted in the presence of hydrogen and a catalyst made by the reaction of organoaluminum or lithium compounds with transition metal salts of 2-ethylhexanoic acid. Falk, Die Angewandte Chemie, 21(286):17-23 (1972), the entire contents of which are also incorporated herein by reference, discloses the hydrogenation of 1,4-polybutadiene segments in a block copolymer of 1,4-polybutadiene-1,4-polyisoprene-1,4-polybutadiene.

[0014] Hoxmeier, Published European Patent Application 88202449.0, filed on Nov. 2, 1988, Publication Number 0 315 280, published on May 10, 1989, discloses a method of selectively hydrogenating a polymer made from at least two different conjugated diolefins. One of the two diolefins is more substituted in the 2, 3 and/or 4 carbon atoms than the other diolefin and produces tri- or tetra-substituted double bond after polymerization. The selective hydrogenation is conducted under such conditions as to hydrogenate the ethylenic unsaturation incorporated into the polymer from the lesser substituted conjugated diolefin, while leaving unsaturated at least a portion of the tri- or tetra-substituted unsaturation incorporated into the polymer by the more substituted conjugated diolefin.

[0015] Mohajer et al., Hydrogenated linear block copolymers of butadiene and isoprene: Effects of variation of composition and sequence architecture on properties, Polymer 23:1523-35 (1982) discloses essentially completely hydrogenated butadiene-isoprene-butadiene (HBIB), HIBI and HBI block copolymers in which butadiene has predominantly 1,4-microstructure.

[0016] Kuraray K K, Japanese published patent application Number JP-328 729, filed on Dec. 12, 1987, published on Jul. 4, 1989, discloses a resin composition comprising 70-99% wt. of a polyolefin (preferably polyethylene or polypropylene) and 1-30% wt. of a copolymer obtained by hydrogenation of at least 50% of unsaturated bond of isoprene/butadiene copolymer.

[0017] The polymerization process for the traditional butene polymers has also generated products having an unacceptably wide distribution of molecular weights, i.e., an unacceptably high ratio of weight average molecular weight (Mw) to number average molecular weight (Mn). Typically, such distributions are Mw/Mn≧2.5.

[0018] Functionalization reactions in these polymers have typically yielded substantial quantities of undesirable by-products such as insoluble modified polymers of variant molecular weight. Functionalization reactions can also result in compounds which contain undesirable chemical moieties such as chlorine.

[0019] Accordingly, it is a purpose of this invention to provide emulsifiers having polymeric structures which permit highly selective control of the degree of unsaturation and consequent functionalization. Unique materials can also be obtained by chemical modification of the polymers of this invention since the polymers can be selectively modified at controllable sites, such as at random sites or at the terminal ends of the molecules.

[0020] It is an additional purpose of this invention to provide a method for the production of explosive emulsion compositions containing polymers having controlled amounts of unsaturation incorporated randomly in an otherwise saturated backbone.

[0021] It is a further purpose of the invention to provide emulsifying polymers having narrow molecular weight distributions and a concomitant lack of undesirable by-products, thereby providing more precisely tailored emulsification properties.

[0022] It is still a further purpose of this invention to provide explosive emulsion compositions with improved properties.

SUMMARY OF THE INVENTION

[0023] The invention provides emulsifiers and explosive emulsions which include polymers of conjugated dienes and/or aryl-substituted olefins which have been hydrogenated, functionalized, and optionally modified. The emulsion properties of the compositions of the invention may be controlled by controlling the size of the polymers and the extent and distribution of their functionalization.

[0024] Block copolymers of butadiene and isoprene may be modified with maleic anhydride according to the present invention and used as emulsifiers for emulsion explosive applications. The activity of the emulsifiers of the present invention is believed to be due to the degree of their maleation (measured by the total acid number) and their molecular weights. Other factors such as the shape of the polymer molecule, the type of monomer blocks and their relative position within the molecule have also shown some influence.

[0025] In the present invention, the emulsifiers are generally based on liquid, low molecular weight polymers generated by anionic block polymerization of dienes, such as butadiene (B) and isoprene (I), and olefins, such as styrene (S). The polymers may be further reacted with maleic anhydride to attach polar hydrophilic moieties (succinic anhydrides).

[0026] Unlike PIBSAs, these new emulsifiers can carry more than one anhydride function per molecule and generally have a higher molecular weight. The anhydride functions can be placed at one end of the molecule (IB), both ends (IBI), in the middle (BIB), randomly (RIB), and on each arm of star shaped polymer (IB Star).

[0027] The invention provides explosive emulsion formulations in which the emulsifier includes polymers of conjugated dienes which may be partially or selectively hydrogenated. In one embodiment of the invention, there is provided an explosive emulsion formulation, in which the emulsifier includes a copolymer of two different conjugated dienes. In this case, the first conjugated diene includes at least one relatively more substituted conjugated diene having at least five carbon atoms and the formula: 1

[0028] wherein R1-R6 are each independently hydrogen or a hydrocarbyl group, provided that at least one of R1-R6 is a hydrocarbyl group, and also provided that, after polymerization, the unsaturation of the polymerized conjugated diene of formula (1) has the formula: 2

[0029] wherein RI, RII, RIII and RIV are each independently hydrogen or a hydrocarbyl group, provided that either both RI and RII are hydrocarbyl groups or both RIII and RIV are hydrocarbyl groups.

[0030] The second conjugated diene in the emulsifier of this embodiment includes at least one relatively less substituted conjugated diene which is different from the first conjugated diene and has at least four carbon atoms and the formula: 3

[0031] wherein R7-R12 are each independently hydrogen or a hydrocarbyl group, provided that, after polymerization, the unsaturation of the polymerized conjugated diene of formula (3) has the formula: 4

[0032] wherein RV, RVI, RVII and RVIII are each independently hydrogen or a hydrocarbyl group, provided that one of RV or RVI is hydrogen, one of RVII or RVIII is hydrogen, and at least one of RV, RVI, RVII and RVIII is a hydrocarbyl group.

[0033] Following polymerization, the diene copolymer may be partially or selectively hydrogenated.

[0034] In a preferred embodiment, the emulsifier includes a polymer in which the first and second conjugated dienes are polymerized as a block copolymer including at least two alternating blocks:

(I)x-(B)y or (B)y—(I)x

[0035] In this case, the block (I) includes at least one polymerized conjugated diene of formula (1), while the block (B) includes at least one polymerized conjugated diene of formula (3). In addition, x is the number of polymerized monomer units in block (I) and is at least 1, and y is the number of polymerized monomer units in block (B) and is at least 25. It should be understood throughout that x and y are defined relative to blocks in a linear block copolymer or blocks in an arm or segment of a branched or star-branched copolymer in which the arm or segment has substantially linear structure.

[0036] Preferably, in the block copolymers of this embodiment, x is at least about 1 and at most about 600, preferably at most about 300, and y is at least about 25 and at most about 2,000, preferably at most about 1,500. While larger values for x and y are generally related to larger molecular weights, polymers which have multiple blocks and star-branched polymers typically will have molecular weights which are not well represented in the values of x and y for each block.

[0037] Alternatively, the emulsifier includes the first and second conjugated dienes polymerized as a random copolymer.

[0038] The emulsifier may include the first and second conjugated dienes polymerized as a branched or star-branched copolymer.

[0039] The copolymers useful according to this embodiment typically have a molecular weight of at least about 2,000, preferably at least about 3,000, and more preferably at least about 5,000. The molecular weight of these polymers is at most about 100,000, preferably at most about 50,000, and more preferably at most about 35,000.

[0040] In the explosive emulsions of the present invention, the copolymer is preferably selectively hydrogenated. It is preferred that the unsaturation of formula (4) be substantially completely hydrogenated, thereby retaining substantially none of the original unsaturation of this type, while the unsaturation of formula (2) is substantially retained (i.e., the residual unsaturation after hydrogenation), in at least an amount which is sufficient to permit functionalization of the copolymer.

[0041] After the hydrogenation reaction, the Iodine Number for the residual unsaturation of formula (2) is generally from about 50% to about 100% of the Iodine Number prior to the hydrogenation reaction. More preferably, after hydrogenation, the Iodine Number for the residual unsaturation of formula (2) is about 100% of the Iodine Number prior to the hydrogenation reaction.

[0042] After the hydrogenation reaction, the Iodine Number for the residual unsaturation of formula (4) is from about 0% to about 10% of the Iodine Number prior to the hydrogenation reaction. More preferably, after the hydrogenation reaction, the Iodine Number for the residual unsaturation of formula (4) is from about 0% to about 0.5% of the Iodine Number prior to the hydrogenation reaction. Most preferably, after the hydrogenation reaction, the Iodine Number for the residual unsaturation of formula (4) is from about 0% to about 0.2% of the Iodine Number prior to the hydrogenation reaction.

[0043] The conjugated diene of formula (1) preferably includes a conjugated diene such as isoprene, 2,3-dimethyl-butadiene, 2-methyl-1,3-pentadiene, myrcene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 2-phenyl-1,3-butadiene, 2-phenyl-1,3-pentadiene, 3-phenyl-1,3 pentadiene, 2,3-dimethyl-1,3-pentadiene, 2-hexyl-1,3-butadiene, 3-methyl-1,3-hexadiene, 2-benzyl-1,3-butadiene, 2-p-tolyl-1,3-butadiene, or mixtures thereof. More preferably, the conjugated diene of formula (1) includes isoprene, myrcene, 2,3-dimethyl-butadiene or 2-methyl-1,3-pentadiene. Still more preferably, the conjugated diene of formula (1) includes isoprene.

[0044] Preferably, the conjugated diene of formula (3) includes 1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 1,3-heptadiene, 2,4-heptadiene, 1,3-octadiene, 2,4-octadiene, 3,5-octadiene, 1,3-nonadiene, 2,4-nonadiene, 3,5-nonadiene, 1,3-decadiene, 2,4-decadiene, 3,5-decadiene, or mixtures thereof. More preferably, the conjugated diene of formula (3) includes 1,3-butadiene, 1,3-pentadiene, or 1,3-hexadiene. Still more preferably, the conjugated diene of formula (3) includes 1,3-butadiene.

[0045] Generally, when the conjugated diene includes substantial amounts of 1,3-butadiene, the polymerized butadiene includes a mixture of 1,4- and 1,2-units. The preferred structures contain at least about 25% of the 1,2-units, preferably at least about 30% of the 1,2-subunits, and more preferably at least about 45% of the 1,2-subunits. The preferred structures contain at most about 95% 1,2-subunits, preferably at most about 90% 1,2-subunits, and more preferably at most about 65% of the 1,2-subunits.

[0046] The polymers are prepared under anionic polymerization conditions. Following polymerization, the polymers of the invention are selectively hydrogenated to provide a controlled amount and extent of residual unsaturation. After the selective hydrogenation reaction, the hydrogenation catalyst is removed from the polymer and the polymer is chemically modified or functionalized to impart desirable characteristics for the explosive emulsion compositions of the invention.

[0047] Accordingly, as a result of the invention, there are now provided emulsifiers and explosive emulsion compositions containing emulsifiers prepared by polymerization of conjugated dienes, followed by selective hydrogenation and functionalization. These emulsifiers of the invention possess numerous advantages, including controlled molecular weight, controlled molecular weight distribution, controlled polymer structure, variable and controlled amounts and distribution of functionality.

[0048] These and other advantages of the present invention will be appreciated from the detailed description and examples which are set forth herein. The detailed description and examples enhance the understanding of the invention, but are not intended to limit the scope of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0049] The polymer component of the explosive emulsion formulations of the present invention provides enhanced stability and effectiveness for aqueous explosive formulations. In one embodiment, the present invention provides polymers including at least two different conjugated dienes, wherein one of the dienes is more substituted in the 2, 3, and/or 4 carbon positions than the other diene. The more substituted diene produces vinylidene, tri-, or tetra-substituted double bonds after polymerization. Hydrogenation of the material is done selectively so as to saturate the lesser substituted olefins, which primarily arise from the lesser substituted diene, while leaving a portion of the more substituted conjugated olefins behind for functionalizing.

[0050] In this embodiment, the more substituted conjugated diene will have at least five (5) carbon atoms and the following formula: 5

[0051] wherein R1-R6 are each independently hydrogen (H) or a hydrocarbyl group, provided that at least one of R1-R6 is a hydrocarbyl group. After polymerization, the unsaturation in the polymerized conjugated diene of formula (1) has the following formula: 6

[0052] wherein RI, RII, RIII and RIV are each independently hydrogen or a hydrocarbyl group, provided that either both RI and RII are hydrocarbyl groups or both RIII and RIV are hydrocarbyl groups. Examples of conjugated dienes of formula (1) include isoprene, 2,3-dimethylbutadiene, 2-methyl-1,3-pentadiene, myrcene, and the like. Isoprene is highly preferred.

[0053] The lesser substituted conjugated diene in this embodiment differs from the other diene in that it has at least four (4) carbon atoms and the following formula: 7

[0054] wherein R7-R12 are each independently hydrogen or a hydrocarbyl group. After polymerization, the unsaturation in the polymerized conjugated diene of formula (3) has the following formula: 8

[0055] wherein RV, RVI, RVII and RVIII are each independently hydrogen (H) or a hydrocarbyl group, provided that one of RV or RVI is hydrogen, one of RVII or RVI is hydrogen, and at least one of RV, RVI, RVII and RVIII is a hydrocarbyl group. Examples of the conjugated diene of formula (3) include 1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene, and the like. A highly preferred conjugated diene of formula (3) is 1,3-butadiene.

[0056] An exception to this scheme would be when a tetra-substituted diene, e.g., 2,3-dimethylbutadiene, is used for the more substituted component. When this occurs, a tri-substituted olefin, e.g. isoprene, may be used for the lesser substituted component, such that one or both of RV and RVI are hydrogen and both RVII and RVIII are hydrocarbyl.

[0057] It will be apparent to those skilled in the art that in the original unsaturation of formula (2), RI, RII, RIII and RIV may all be hydrocarbyl groups, whereas in the original unsaturation of formula (4) at least one of RV, RVI, RVII and RVIII must be a hydrogen.

[0058] The hydrocarbyl group or groups in the formula (1) to (4) are the same or different and they are substituted or unsubstituted alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, alkaryl, or aralkyl groups, or any isomers thereof.

[0059] The copolymers of this embodiment are prepared by anionically polymerizing a diene of formula (1) at a level of from about 0.5% wt. to about 25% wt., and a diene of formula (3) at a level of from about 75% wt. to about 99.5% wt., in a hydrocarbon solvent using an alkyllithium catalyst. The two monomers can be polymerized in block, tapered block, or random fashion. Since the polymerization is anionic, the molecular weight distribution of these copolymers is typically very narrow, generally ranging from about 1.01 to about 1.20, and the molecular weight is determined by the ratio of monomer to initiator and/or by the presence of coupling agents. The monomers (1) and (3) may be polymerized either simultaneously or in stepwise fashion depending on the desired position of the remaining unsaturation after hydrogenation. If random positioning of the unsaturation is desired, both monomers are reacted together to give a random copolymer. If it is desirable to have the functionality on only one end, then the monomers are reacted in stepwise fashion, the order being determined as desired, to provide a diblock copolymer. If functionality is needed on both ends, then a conjugated diene of formula (1) is polymerized first, followed by a diene of formula (3). To the living anion, a coupling agent, e.g., phenyl benzoate or methyl benzoate, is then added to yield a desired triblock copolymer. Alternatively, a diene of formula (1) may be added to the living diblock to give the triblock.

[0060] A fourth approach would allow the functionality to be positioned in the center of the polymer chain. In this case, a diene of formula (3) is polymerized first, followed by a diene of formula (1). Then a triblock is formed by addition of a coupling agent or by addition of more diene of formula (3). In addition, combinations of the above approaches may be employed.

[0061] The explosive emulsion formulations of the invention can include polymers of differing microstructures. The presence of polar modifier increases the activity of the catalyst and enhances the level of 1,2-microstructure over 1,4-microstructure in polybutadiene, for example. The percentage of vinyl obtained is proportional to the concentration of the modifier employed. Since the reaction temperature also plays a role in determining the microstructure of polybutadiene, the level of modifier must be chosen taking into account the combined effects. Antkowiak et al., Temperature and Concentration Effects on Polar-modified Alkyl Lithium Polymerizations and Copolymerizations, Journal of Polymer Science: Part A-1, 10:1319-34 (1972), incorporated herein by reference have presented a way for quickly determining the proper conditions for preparation of any 1,2-microstructure content within a range of from about 10% to about 80%. Use of this method or any others to achieve the desired microstructure will be known to anyone who is skilled in the art.

[0062] The emulsifiers and explosive emulsion compositions of the invention can include different polymer macrostructures. Polymers may be prepared and utilized having linear and/or nonlinear, e.g., star-branched, macrostructures. The star-branched polymers can be prepared by addition of divinylbenzene or the like to the living polymer anion. Lower levels of branching can be obtained through the use of tri-functional or tetra-functional coupling agents, such as tetrachlorosilane.

[0063] In all embodiments of this invention, whenever a reference is made to the “original double bond” or the “original unsaturation” of the block or random polymer (or copolymer), it is understood to mean the double bond(s) in the polymer prior to the hydrogenation reaction. By contrast, the terms “residual double bond(s)” and “residual unsaturation”, as used herein, refer to the unsaturated group(s), typically excluding aromatic unsaturation, present in the copolymer after the selective hydrogenation reaction.

[0064] The molecular structure of the original or residual double bonds can be determined in any conventional manner, as is known to those skilled in the art, e.g., by infrared (IR) or nuclear magnetic resonance (NMR) analysis. In addition, the total original or residual unsaturation of the polymer can be quantified in any conventional manner, e.g., by reference to the Iodine Number of the polymer.

[0065] In any polymers of any of the embodiments of this invention, the microstructure of the polymerized conjugated diene of formula (3) must be such that the polymer is not excessively crystalline after the selective hydrogenation reaction. That is, after the selective hydrogenation reaction the polymer must retain its elastomeric properties, e.g., the polymer should contain not more than about 10% of polyethylene crystallinity. Generally, problems of crystallinity occur only when the polymer includes polymerized 1,3-butadiene. Limiting polymeric crystallinity may be accomplished in various ways. For example, this is accomplished by introducing side branches into the polymerized conjugated dienes of formula (1) and/or (3), e.g., by controlling the microstructure of 1,3-butadiene if it is the predominant monomer in the diene of formula (3); by using a mixture of dienes of formula (3) containing less than predominant amounts of 1,3-butadiene; or by using a single diene of formula (3), other than 1,3-butadiene. More particularly, if the conjugated diene(s) of formula (3) is predominantly (at least 50% by mole) 1,3-butadiene, the side branches are introduced into the polymer by insuring that the polymerized diene of formula (3) contains a sufficient amount of the 1,2-units to prevent the selectively hydrogenated polymer from being excessively crystalline. Thus, if the conjugated diene of formula (3) is predominantly (at least 50% by mole, e.g., 100% by mole) 1,3-butadiene, the polymerized diene of formula (3), prior to the selective hydrogenation reaction, must contain at most about 75% wt., preferably at most about 70% wt., and more preferably at most about 55% wt. of the 1,4-units and at least about 5% wt., preferably at least about 10% wt., and more preferably at least about 35% wt. of the 1,4-units. If the conjugated diene of formula (3) is predominantly (at least 50% by mole, e.g., 100% by mole) 1,3-butadiene, the polymerized diene of formula (3), prior to the selective hydrogenation reaction, must contain at least about 25% wt., preferably at least about 30% wt., and most preferably at least about 45% wt. of the 1,2-units and at most about 95% wt., preferably at most about 90% wt., and more preferably at most about 65% wt. of the 1,2-units. If the polymerized diene(s) of formula (3) contains less than 50% by mole of 1,3-butadiene, e.g., 1,3-pentadiene is used as the only diene of formula (3), the microstructure of the polymerized diene of formula (3) prior to the selective hydrogenation reaction is not critical since, after hydrogenation, the resulting polymer will contain substantially no crystallinity. Alternatively, low melting solids (e.g. 25 to 35° C.) may be prepared by controlling 1,2-units to 30 wt. % or less.

[0066] Homopolymers of a conjugated diene may be used to prepare polymers of the present invention in linear, branched or star branched form. The homopolymers may be partially hydrogenated such that they possess an iodine number of 1-150, preferably 2-100. Mixtures of dienes of formula (1) or (3) may be used to prepare block copolymers (I)x-(B)y or any of the random copolymers or star-branched block and random polymers of the invention. Similarly, mixtures of aryl-substituted olefins may also be used to prepare block, random, or star-branched copolymers of this invention. Accordingly, whenever a reference is made herein to a diene of formula (1) or (3), or to an aryl-substituted olefin, it may encompass more than one diene of formula (1) or (3), respectively, and more than one aryl-substituted olefin.

[0067] The block copolymers of this invention comprise two or more alternating blocks, identified above. Linear block copolymers having two blocks and block copolymers having three or more blocks are contemplated herein.

[0068] The block polymers useful according to the invention typically include at least one block which is substantially completely saturated, while also including at least one block containing controlled levels of unsaturation providing a hydrocarbon elastomer with selectively positioned unsaturation for subsequent functionalization. For the copolymers prepared from two different conjugated dienes, it has been found that the two dienes in the copolymers hydrogenate at different rates, permitting selective control of the placement of residual unsaturation.

[0069] The many variations in composition, molecular weight, molecular weight distribution, relative block lengths, microstructure, branching, and Tg (glass transition temperature) attainable with the use of anionic techniques employed in the preparation of our polymers will be obvious to those skilled in the art.

[0070] While not wishing to limit the molecular weight range of liquid elastomers prepared according to our invention, the minimum molecular weight for these liquid polymers is at least about 2,000, preferably at least about 3,000, and more preferably at least about 5,000. The maximum molecular weight for these liquid polymers is at most about 100,000, preferably at most about 50,000, and more preferably at most about 35,000. The star-branched block and random copolymers of this invention may have substantially higher molecular weights and still retain liquid properties. The block copolymers of this invention are functionalizable. Without wishing to be bound by any theory of operability, it is believed that they can be functionalized in a controlled manner through the unsaturated groups on the terminal or the interior blocks to provide emulsifiers for explosive emulsion compositions having almost uniform distribution of molecular weights.

[0071] The star-branched and linear versions of the random copolymers and homopolymers of this invention are also functionalizable.

[0072] All numerical values of molecular weight given in this specification and the drawings are of number average molecular weight (Mn).

[0073] The invention will be described hereinafter in terms of the embodiments thereof summarized above. However, it will be apparent to those skilled in the art, that the invention is not limited to these particular embodiments, but, rather, it covers all the embodiments encompassed by the broadest scope of the description of the invention.

[0074] Copolymers from at Least Two Dissimilar Conjugated Dienes

[0075] In this embodiment of the invention, there are provided copolymers of two dissimilar conjugated dienes, preferably isoprene and 1,3-butadiene. The two monomers can be polymerized by anionic polymerization process in either a block, tapered block, or random fashion.

[0076] The copolymers of this embodiment include a first conjugated diene having at least five (5) carbon atoms and the following formula: 9

[0077] wherein R1-R6 are each independently hydrogen or a hydrocarbyl group, provided that at least one of R1-R6 is a hydrocarbyl group, and further provided that, when polymerized, the structure of the double bond in the polymerized conjugated diene of formula (1) has the following formula: 10

[0078] wherein RI, RII, RIII and RIV are each independently hydrogen or a hydrocarbyl group, provided that either both RI and RII are hydrocarbyl groups or both RIII and RIV are hydrocarbyl groups. In the double bond of the polymerized conjugated diene of formula (2), RI, RII, RIII and RIV may all be hydrocarbyl groups.

[0079] The polymers of this embodiment also include a second conjugated diene, different from the first conjugated diene, having at least four (4) carbon atoms and the following formula: 11

[0080] wherein R7-R12 are each independently hydrogen or a hydrocarbyl group, provided that the structure of the double bond in the polymerized conjugated diene of formula (3) has the following formula: 12

[0081] wherein RV, RVI, RVII and RVIII are each independently hydrogen (H) or a hydrocarbyl group, provided that one of RV or RVI is hydrogen, one of RVII or RVI is hydrogen, and at least one of RV, RVI, RVII and RVIII is a hydrocarbyl group.

[0082] The polymers of this embodiment include a first conjugated diene of formula (1) in an amount of at least about 0.5% wt., preferably at least about 1% wt., and more preferably at least about 5% wt. The polymers of this embodiment include a first conjugated diene of formula (1) in an amount of at most about 30% wt., preferably at most about 25% wt., and more preferably at most about 20% wt. The second conjugated diene of formula (3) is in an amount of at least about 70% wt., preferably at least about 75% wt., and more preferably at least about 80% wt. The second conjugated diene of formula (3) is in an amount of at most about 99.5 wt. %, preferably at most about 99% wt., and more preferably at most about 95% wt.

[0083] The polymers of this embodiment include block copolymers having at least two alternating blocks:

(I)x-(B)y or (B)y-(I)x

[0084] In this case, the polymer includes at least one block (I). The block (I) is a block of at least one polymerized conjugated diene of formula (1) as described above. These block copolymers also include at least one polymerized block (B). The block (B) is a block of at least one polymerized conjugated diene of formula (3) described above.

[0085] In the block copolymers of this embodiment, x is at least 1 and at most about 600, preferably at most about 300. The above definition of x means that each of the (I) blocks is polymerized from at least 1, preferably about 1-600, and more preferably about 1-350, monomer units.

[0086] In the block copolymers of this embodiment, y is at least 25, preferably at least about 30, and at most about 2,000, preferably at most about 1,500. The above definition of y means that each of the (B) blocks is polymerized from at least 25, preferably about 30-2,000, and more preferably about 30-1,500, monomer units.

[0087] The block copolymer comprises at least about 0.5%, preferably at least about 1%, and at most about 25%, preferably at most about 20% by wt. of the (I) blocks, and at least about 75%. preferably at least about 80%, and at most about 99.5%, preferably at most about 99% by wt. of the (B) blocks.

[0088] In any of the copolymers of this embodiment, the structures of the double bonds defined by formula (2) and (4) are necessary to produce copolymers which can be selectively hydrogenated in the manner described herein, to produce the selectively hydrogenated block and random copolymers of this invention.

[0089] The hydrocarbyl group or groups in formulae (1) and (2) are the same or different and they are substituted or unsubstituted alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, alkaryl, or aralkyl groups, or any isomers thereof. Suitable hydrocarbyl groups are alkyls of 1-20 carbon atoms, alkenyls of 1-20 carbon atoms, cycloalkyls of 5-20 carbon atoms, aryls of 6-12 carbon atoms, alkaryls of 7-20 carbon atoms or aralkyls of 7-20 carbon atoms. Examples of suitable alkyl groups are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, methyl-decyl or dimethyl-decyl. Examples of suitable alkenyl groups are ethenyl, propenyl, butenyl, pentenyl or hexenyl. Examples of suitable cycloalkyl groups are cyclohexyl or methylcyclohexyl. Examples of suitable cycloalkenyl groups are 1-, 2-, or 3-cyclohexenyl or 4-methyl-2-cyclohexenyl. Examples of suitable aryl groups are phenyl or diphenyl. Examples of suitable alkaryl groups are 4-methyl-phenyl (p-tolyl) or p-ethyl-phenyl. Examples of suitable aralkyl groups are benzyl or phenethyl. Suitable conjugated dienes of formula (1) used to polymerize the (I) block are isoprene, 2,3-dimethyl-butadiene, 2-methyl-1,3-pentadiene, myrcene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 2-phenyl-1,3-butadiene, 2-phenyl-1,3-pentadiene, 3-phenyl-1,3 pentadiene, 2,3-dimethyl-1,3-pentadiene, 2-hexyl-1,3-butadiene, 3-methyl-1,3-hexadiene, 2-benzyl-1,3-butadiene, 2-p-tolyl-1,3-butadiene, or mixtures thereof, preferably isoprene, myrcene, 2,3-dimethyl-butadiene, or 2-methyl-1,3-pentadiene, and most preferably isoprene.

[0090] The hydrocarbyl group or groups in the formula (3) may or may not be the same as those in formula (4). These hydrocarbyl groups are the same as those described above in conjunction with the discussion of the hydrocarbyl groups of formula (1) and (2). Suitable monomers for the (B) block are 1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene, 1,3-hexadiene, 1,3-heptadiene, 2,4-heptadiene, 1,3-octadiene, 2,4-octadiene, 3,5-octadiene, 1,3-nonadiene, 2,4-nonadiene, 3,5-nonadiene, 1,3-decadiene, 2,4-decadiene, 3,5-decadiene, or mixtures thereof, preferably 1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene, or 1,3-hexadiene, and most preferably it is 1,3-butadiene. It is generally preferred that each of the (B) blocks is polymerized from a single monomer.

[0091] The scope of this embodiment, and of any other embodiments of the invention wherein the block (B) is used, also encompasses polymers wherein the block (B) may comprise copolymers of one or more conjugated diene of formula (3) and controlled amounts (about 0.3 to about 30 mole %) of an aryl-substituted olefin, e.g., styrene or other suitable monomers (such as alkylated styrene, vinyl naphthalene, or alkylated vinyl naphthalene) incorporated for control of glass transition temperature (Tg), density, solubility parameters and refractive index. Similarly, the scope of this embodiment also encompasses polymers wherein the block (B) may be comprised of copolymers of one or more conjugated diene of formula (3) and any other anionically polymerizable monomer capable of polymerizing with the conjugated diene of formula (3). Similar considerations also apply in the case of the (I) block(s), which can include similar styrene/diene copolymers.

[0092] The copolymer is polymerized by anionic polymerization, discussed in detail below. As will be apparent to those skilled in the art, the block copolymer of this embodiment contains at least two alternating blocks, (I)-(B) or (B)-(I), referred to herein as diblocks. The block copolymer of this embodiment may contain three alternating blocks, e.g., (I)-(B)-(I), referred to herein as triblocks or triblock units, but it may contain an unlimited number of blocks. The functionalization of any of these copolymers is conducted in a conventional manner and is described below.

[0093] After the (I)-(B) copolymer is polymerized, it is subjected to a selective hydrogenation reaction during which the polymerized conjugated dienes of formula (1) and (3) of the copolymer are selectively hydrogenated to the desired extent.

[0094] Generally, for a copolymer wherein the conjugated dienes of formula (1) and (3) are polymerized to provide unsaturation of formula (2) and (4), respectively, as discussed above, the Iodine Number for the unsaturation of formula (2) after the selective hydrogenation reaction is at least about 20%, preferably at least about 50% and more preferably about 100%, of the Iodine Number prior to the selective hydrogenation reaction. For the unsaturation of formula (4) it is at most about 10%, preferably at most about 0.5%, more preferably at most about 0.2%, and even more preferably about 0%, of the Iodine Number prior to the selective hydrogenation reaction. The Iodine Number, as is known to those skilled in the art, is defined as the theoretical number of grams of iodine which will add to the unsaturation in 100 grams of olefin and is a quantitative measure of unsaturation.

[0095] In this embodiment of the invention, although the microstructure of the (1) blocks is not critical and may consist of 1,2-, 3,4- and/or 1,4-units, schematically represented below for the polyisoprene blocks, 13

[0096] when a polar compound is used during the polymerization of the (I) block, the (I) blocks comprise primarily (at least about 50% wt.) 3,4-units, the rest being primarily (less than about 50% wt.) 1,4-units; when the polar compound is not used during the polymerization of the (I) block, the (I) blocks comprise primarily (about 80% wt.) 1,4-units, the rest being primarily 1,2- and 3,4- units.

[0097] The microstructure of the (B) blocks, when the predominant monomer used to polymerize the (B) blocks is 1,3-butadiene, should be a mixture of 1,4- and 1,2- units schematically shown below for the polybutadiene blocks: 14

[0098] since the hydrogenation of the predominantly 1,4-microstructure produces a crystalline polyethylene segment. The microstructure of the (I) and (B) blocks (as well as of the polymerized conjugated dienes of formula (1) or (3) in any polymers of this invention) is controlled in a conventional manner, e.g., by controlling the amount and nature of the polar compounds used during the polymerization reaction, and the reaction temperature. In one particularly preferred embodiment, the (B) block contains about 50% of the 1,2- and about 50% of the 1,4- microstructure. If the (B) block is poly-1,3-butadiene, the hydrogenation of the (B) segment containing from about 50% to about 60% of the 1,2-microstructure content produces an elastomeric center block which is substantially an ethylene-butene-1 copolymer having substantially no crystallinity. If the (B) block is polymerized from 1,3-pentadiene, the microstructure is not critical.

[0099] The terms “1,2-”, “1,4-”, and “3,4-microstructure” or “units” as used in this application refer to the products of polymerization obtained by the 1,2-, 1,4- and 3,4-, respectively, mode of addition of monomer units.

[0100] We surprisingly discovered that the polymerized conjugated dienes of formula (3), e.g., the dienes employed in (B) blocks, of the polymers of this invention are selectively hydrogenated in our hydrogenation process much faster than the polymerized conjugated dienes of formula (1), e.g., the dienes used in the (I) blocks. This is not evident from the teachings of Falk, discussed above, because Falk teaches that double bonds of the di-substituted 1,4-polybutadiene units are hydrogenated selectively in the presence of double bonds of the tri-substituted 1,4-polyisoprene units (which hydrogenate very slowly). We surprisingly discovered that the di-substituted double bonds of the 1,4-polybutadiene units are hydrogenated along with the monosubstituted double bonds of the 1,2-polybutadiene units, while the di-substituted double bonds of the 3,4-polyisoprene units are hydrogenated at a much slower rate than the aforementioned polybutadienes. Thus, in view of Falk's disclosure it is surprising that the di-substituted double bonds of the 1,4-polybutadiene units are hydrogenated selectively in the presence of the di-substituted double bonds of the 3,4-polyisoprene units. This is also surprising in view of the teachings of Hoxmeier, Published European Patent Application, Publication No. 0 315 280, who discloses that the di-substituted double bonds of the 1,4-polybutadiene units, monosubstituted double bonds of the 1,2-polybutadiene units and di-substituted double bonds of the 3,4-polyisoprene units are hydrogenated simultaneously at substantially the same rates. For example, for the block copolymers of this invention, wherein the (I) block is polyisoprene and the (B) block is polybutadiene, Fourier Transform Infrared (FTIR) analysis of selectively hydrogenated block copolymers of the invention, such as I-B-I triblock polymers, indicates that the hydrogenation of the double bonds of the 1,2-polybutadiene units proceeds most rapidly, followed by the hydrogenation of the double bonds of the 1,4-polybutadiene units. Infrared absorptions caused by these groups disappear prior to appreciable hydrogenation of the polyisoprene units.

[0101] Accordingly, by controlling the amount and placement of 1,2- versus 1,4-microstructure, as well as the amount and placement of polyisoprene units, it is now possible to control the amount and placement of unsaturation remaining in the polymers after hydrogenation. It follows that the amount and placement of functionalization of the polymeric emulsifiers of the invention is also controllable to an extent not possible previously.

[0102] After the block copolymer is prepared, it is subjected to a selective hydrogenation reaction to hydrogenate primarily the (B) block(s). The selective hydrogenation reaction and the catalyst are described in detail below. After the hydrogenation reaction is completed, the selective hydrogenation catalyst is removed from the block copolymer, and the polymer is isolated by conventional procedures, e.g., alcohol flocculation, steam stripping of solvent, or non-aqueous solvent evaporation. An antioxidant, e.g., Irganox 1076 (from Ciba), is normally added to the polymer solution prior to polymer isolation.

[0103] Random Copolymers

[0104] Random copolymers of this invention have controlled amounts of unsaturation incorporated randomly in an otherwise saturated backbone. In contrast to EPDM, the level of unsaturation can be easily controlled, e.g., to produce polymers having Iodine Number of from about 5 to about 100, to provide a wide variation in the degree of functionalization.

[0105] In one embodiment, the random copolymers are polymerized from the same monomers used to polymerize the block copolymers (I)x-(B)y, described elsewhere herein. In particular, the random copolymers may be made by polymerizing at least one conjugated diene of formula (1) with at least one conjugated diene of formula (3), both defined above. This random copolymer contains at least about 1.0% and at most about 40%, preferably at most about 20%, by mole of the polymerized conjugated diene of formula (1) and at least about 60%, preferably at least about 80% and at most about 99% by mole of the polymerized conjugated diene of formula (3). Suitable conjugated dienes of formula (1) are exemplified above. The most preferred conjugated diene of formula (1) for the copolymerization of these random copolymers is isoprene. Suitable conjugated dienes of formula (3) are also exemplified above. 1,3-butadiene is the most preferred conjugated diene of formula (3) for the polymerization of the random copolymer of this embodiment. Thus, most preferably, in this embodiment, the random copolymer is polymerized from isoprene and 1,3-butadiene, and it contains from about 1% wt. to about 20% wt. of the isoprene units and from about 80% wt. to about 99% wt. of the butadiene units. The isoprene units have primarily (i.e., from about 50% wt. to about 90% wt.) the 3,4-microstructure.

[0106] The random copolymers are subjected to the selective hydrogenation reaction discussed above for the block copolymers, during which polymerized conjugated diene units of formula (3) are substantially completely hydrogenated, while the polymerized conjugated diene units of formula (1) are hydrogenated to a substantially lesser extent, i.e., to such an extent that they retain a sufficient amount of their original unsaturation to functionalize the copolymer, thereby producing emulsifiers having random unsaturation proportional to the unsaturation in the polymerized dienes of formula (1). For example, for random copolymer polymerized from a diene of formula (1) and a different diene of formula (3), the Iodine Number before selective hydrogenation for the polymer is about 450. After selective hydrogenation, the Iodine Number for the polymer is from about 10 to about 50, with most of the unsaturation being contributed by the diene of formula (1).

[0107] The hydrogenated random copolymers are functionalized in the same manner as set forth for block copolymers.

[0108] Star-Branched Polymers

[0109] The invention is also directed to star-branched block and random polymers. The star-branched block polymers are made from any combination of blocks (I) and (B), defined above.

[0110] The star-branched (I)-(B) block polymers comprise at least about 0.5% wt., preferably at least about 1% wt. and at most about 25% wt., preferably at most about 20% wt., of the (I) blocks, and at least about 75% wt., preferably at least about 80% wt. and at most about 99.5% wt., preferably at most about 99% wt., of the (B) blocks.

[0111] The star-branched block polymers are selectively hydrogenated in the selective hydrogenation process of this invention to such an extent that blocks (B) contain substantially none of the original unsaturation, while each of the blocks (I) respectively, retains a sufficient amount of the original unsaturation of the conjugated dienes present in these blocks to functionalize the star-branched block polymers. Thus, for the I-(B) star-branched block polymer, after the selective hydrogenation reaction, the Iodine Number for the (I) blocks is at least about 10%, preferably at least about 25%, more preferably at least about 50%, and even more preferably about 100%, of the Iodine Number prior to the selective hydrogenation reaction; and for the (B) blocks it is at most about 10%, preferably at most about 0.5%, and more preferably about 0% of the Iodine Number prior to the selective hydrogenation reaction.

[0112] The star-branched random polymers are made from any combination of at least one diene of formula (1) and at least one diene of formula (3), different from the diene of formula (1), or from any combination of at least one aryl-substituted olefin and at least one diene of formula (1) or (3), all of which are the same as those discussed above. The star-branched random polymers of the dienes of formula (1) and (3), which must be different from each other, comprise at least about 0.5% wt., preferably at least about 1% wt., and at most about 25% wt., preferably at most about 20% wt., of the diene of formula (1), and at least about 75% wt., preferably at least about 80% wt., and at most about 99.5% wt., preferably at most about 99% wt., of the diene of formula (3). The star-branched random polymers of the aryl-substituted olefin and the diene of formula (1) or (3) comprise at least about 0.5% wt., preferably at least about 1% wt., and at most about 50% wt., preferably at most about 25% wt., of the aryl-substituted olefin, and at least about 50% wt., preferably at least about 75% wt., and at most about 99.5% wt., preferably at most about 99% wt., of the diene of formula (1) or (3).

[0113] The star-branched random diene polymers are also subjected to the selective hydrogenation reaction discussed above for the block copolymers.

[0114] Polymerization Reaction

[0115] The polymers of this invention are polymerized by any known polymerization process, preferably by an anionic polymerization process. Anionic polymerization is well known in the art and it is utilized in the production of a variety of commercial polymers. An excellent comprehensive review of anionic polymerization processes appears in the text Advances in Polymer Science 56, Anionic Polymerization, pp. 1-90, Springer-Verlag, Berlin, Heidelberg, New York, Tokyo 1984 in a monograph entitled Anionic Polymerization of Non-polar Monomers Involving Lithium, by R. N. Young, R. P. Quirk and L. J. Fetters, incorporated herein by reference. The anionic polymerization process is conducted in the presence of a suitable anionic catalyst (also known as an initiator), such as n-butyl-lithium, sec-butyl-lithium, t-butyl-lithium, sodium naphthalide or, cumyl potassium. The amount of the catalyst and the amount of the monomer in the polymerization reaction dictate the molecular weight of the polymer. The polymerization reaction is conducted in solution using an inert solvent as the polymerization medium, e.g., aliphatic hydrocarbons, such as hexane, cyclohexane, or heptane, or aromatic solvents, such as benzene or toluene. In certain instances, inert polar solvents, such as tetrahydrofuran, can be used alone as a solvent, or in a mixture with a hydrocarbon solvent.

[0116] The polymerization process will be exemplified below for the polymerization of one of the embodiments of the invention, e.g., a triblock of polyisoprene-polybutadiene-polyisoprene. However, it will be apparent to those skilled in the art that the same process principles can be used for the polymerization of all polymers of the invention.

[0117] The process, when using a lithium-based catalyst, comprises forming a solution of the isoprene monomer in an inert hydrocarbon solvent, such as cyclohexane, modified by the presence therein of one or more polar compounds selected from the group consisting of ethers, thioethers, and tertiary amines, e.g., tetrahydrofuran. The polar compounds are necessary to control the microstructure of the butadiene center block, i.e., the content of the 1,2-structure thereof. The higher the content of the polar compounds, the higher will be the content of the 1,2-structure in these blocks. Since the presence of the polar compound is not essential in the formation of the first polymer block with many initiators unless a high 3,4-structure content of the first block is desired, it is not necessary to introduce the polar compound at this stage, since it may be introduced just prior to or together with the addition of the butadiene in the second polymerization stage. Examples of polar compounds which may be used are dimethyl ether, diethyl ether, ethyl methyl ether, ethyl propyl ether, dioxane, diphenyl ether, dipropyl ether, tripropyl amine, tributyl amine, trimethyl amine, triethyl amine, and N-N-N′-N′-tetramethyl ethylene diamine. Mixtures of the polar compounds may also be used. The amount of the polar compound depends on the type of the polar compound and the polymerization conditions as will be apparent to those skilled in the art. The effect of polar compounds on the polybutadiene microstructure is detailed in Antkowiak et al. The polar compounds also accelerate the rate of polymerization. If monomers other than 1,3-butadiene, e.g., pentadiene, are used to polymerize the central blocks (B), polar compounds are not necessary to control the microstructure because such monomers will inherently produce polymers which do not possess crystallinity after hydrogenation.

[0118] When the alkyl lithium-based initiator, a polar compound and an isoprene monomer are combined in an inert solvent, polymerization of the isoprene proceeds to produce the first terminal block whose molecular weight is determined by the ratio of the isoprene to the initiator. The living polyisoprenyl anion formed in this first step is utilized as the catalyst for further polymerization. At this time, butadiene monomer is introduced into the system and block polymerization of the second block proceeds, the presence of the polar compound now influencing the desired degree of branching (1,2-structure) in the polybutadiene block. The resulting product is a living diblock polymer having a terminal anion and a lithium counterion. The living diblock polymer serves as a catalyst for the growth of the final isoprene block, formed when isoprene monomer is again added to the reaction vessel to produce the final polymer block, resulting in the formation of the I-B-I triblock. Upon completion of polymerization, the living anion, now present at the terminus of the triblock, is destroyed by the addition of a proton donor, such as methyl alcohol or acetic acid. The polymerization reaction is usually conducted at a temperature of between about 0° C. and about 100° C., although higher temperatures can be used. Control of a chosen reaction temperature is desirable since it can influence the effectiveness of the polar compound additive in controlling the polymer microstructure. The reaction temperature can be, for example, from about 50° C. to about 80° C. The reaction pressure is not critical and varies from about atmospheric to about 100 psig.

[0119] If the polar compounds are utilized prior to the polymerization of the first (I) segment, (I) blocks with high 3,4-unit content are formed. If polar compounds are added after the initial (I) segment is prepared, the first (I) segment will possess a high percentage of 1,4-microstructure (which is tri-substituted), and the second (1) segment will have a high percentage of 3,4-microstructure.

[0120] The production of triblock polymers having a high 1,4-unit content on both of the terminal (I) blocks is also possible by the use of coupling techniques illustrated below for a polyisoprene-polybutadiene-polyisoprene block copolymer: 15

[0121] The substitution of myrcene for the isoprene during the polymerization of the (I) blocks insures the incorporation of a high proportion of tri-substituted double bonds, even in the presence of polar compounds since myrcene contains a pendant tri-substituted double bond which is not involved in the polymerization process. In a coupling process, similar to that described above, block polymers containing polyisoprene end blocks (or any other polymerized monomer suitable for use in the (I) block) having a high 3,4-microstructure content can be obtained by adding the polar compound prior to the isoprene (or another monomer) polymerization.

[0122] The use of the coupling technique for the production of triblock polymers reduces the reaction time necessary for the completion of polymerization, as compared to sequential addition of isoprene, followed by butadiene, followed by isoprene. Such coupling techniques are well known and utilize coupling agents such as esters, CO2, iodine, dihaloalkanes, silicon tetrachloride, divinyl benzene, alkyl trichlorosilanes and dialkyl dichlorosilanes. The use of tri- or tetra-functional coupling agents, such as alkyl trichlorosilanes or silicon tetrachloride, permits the formation of macromolecules having 1- or 2- main chain branches, respectively. The addition of divinyl benzene as a coupling agent has been documented to produce molecules having up to 20 or more separately joined segments.

[0123] The use of some of the coupling agents provides a convenient means of producing star-branched block and random polymers. The star-branched block polymers are made from any combination of blocks (I) and (B), defined above. The star-branched random polymers are made from any combination of at least one diene of formula (1) and at least one diene of formula (3), different from the diene of formula (1), or from at least one aryl-substituted olefin, at least one diene of formula (1) and at least one diene of formula (3), different from the diene of formula (1). The molecular weight of the star-branched block and random copolymers will depend on the number of branches in each such copolymer, as will be apparent to those skilled in the art. Suitable coupling agents and reactions are disclosed in the following references which are incorporated herein by reference: U.S. Pat. Nos. 3,949,020; 3,594,452; 3,598,887; 3,465,065; 3,078,254; 3,766,301; 3,632,682; 3,668,279; and Great Britain Patent Nos. 1,014,999; 1,074,276; 1,121,978.

[0124] Hydrogenation

[0125] Following polymerization, the polymers may be selectively or partially hydrogenated. Selective hydrogenation of the polymer may be accomplished using techniques similar to those known in the art. A preferred method and catalyst are described in U.S. Pat. No. 5,187,236, the disclosure of which is incorporated herein by reference. The procedure and catalyst are described in greater detail below. In general, however, the previously described polymers can be contacted with hydrogen and a hydrogenation catalyst synthesized from a transition metal compound, typically nickel or cobalt, and an organometallic reducing agent, e.g., triethylaluminum. The hydrogenation proceeds at temperatures typically not in excess of about 40 EC and at pressures of from about 30 psi to about 100 psi. Generally, the polymers are hydrogenated such that substantially all of the unsaturation in formula (4) is removed, while much of that from formula (2) is retained.

[0126] The selective hydrogenation reaction will also be described below using a triblock of polyisoprene-polybutadiene-polyisoprene as an example. However, it will be apparent to those skilled in the art that any polymers of this invention can be selectively hydrogenated in the same manner.

[0127] In Example II below, the block copolymer is selectively hydrogenated to saturate the end (polybutadiene) block. The method of selectively hydrogenating the polybutadiene block is similar to that of Falk, Coordination Catalysts for the Selective Hydrogenation of Polymeric Unsaturation, Journal of Polymer Science: Part A-1, 9:2617-23 (1971), but it is conducted with a novel hydrogenation catalyst and process used herein. Any other known selective hydrogenation methods may also be used, as will be apparent to those skilled in the art, but it is preferred to use the method described herein. In summary, the selective hydrogenation method preferably used herein comprises contacting the previously-prepared block copolymer with hydrogen in the presence of the novel catalyst composition.

[0128] The novel hydrogenation catalyst composition and hydrogenation process are described in detail in previously cited application Ser. No. 07/466,136, which is fully incorporated by reference. The hydrogenation catalyst composition is synthesized from at least one transition metal compound and an organometallic reducing agent. Suitable transition metal compounds are compounds of metals of Group IVb, Vb, VIb or VIII, preferably UVb or VIII of the Periodic Table of the Elements, published in Lange's Handbook of Chemistry, 13th Ed., McGraw-Hill Book Company, New York (1985) (John A. Dean, ed.). Non-limiting examples of such compounds are metal halides, e.g., titanium tetrachloride, vanadium tetrachloride; vanadium oxytrichloride, titanium and vanadium alkoxides, wherein the alkoxide moiety has a branched or unbranched alkyl radical of 1 to about 20 carbon atoms, preferably 1 to about 6 carbon atoms. Preferred transition metal compounds are metal carboxylates or alkoxides of Group IVb or VIII of the Periodic Table of the Elements, such as nickel (II) 2-ethylhexanoate, titanium isopropoxide, cobalt (II) octoate, nickel (II) phenoxide and ferric acetylacetonate.

[0129] The organometallic reducing agent is any one or a combination of any of the materials commonly employed to activate Ziegler-Natta olefin polymerization catalyst components containing at least one compound of the elements of Groups Ia, IIa, IIb, IIIa, or IVa of the Periodic Table of the Elements. Examples of such reducing agents are metal alkyls, metal hydrides, alkyl metal hydrides, alkyl metal halides, and alkyl metal alkoxides, such as alkyllithium compounds, dialkylzinc compounds, trialkylboron compounds, trialkylaluminum compounds, alkylaluminum halides and alkylaluminum hydrides, and tetraalkylgermanium compounds. Mixtures of the reducing agents may also be employed. Specific examples of useful reducing agents include n-butyllithium, diethylzinc, di-n-propylzinc, triethylboron, diethylaluminumethoxide, triethylaluminum, trimethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, ethylaluminum dichloride, ethylaluminum dibromide, ethylaluminum dihydride, isobutylaluminum dichloride, isobutylaluminum dibromide, isobutyaluminum dihydride, diethylaluminum chloride, diethylaluminum bromide, diethylaluminum hydride, di-n-propylaluminum chloride, di-n-propylaluminum bromide, di-n-propylaluminum hydride, diisobutylaluminum chloride, diisobutylaluminum bromide diisobutylaluminum hydride, tetramethylgermanium, and tetraethylgermanium. Organometallic reducing agents which are preferred are Group IIIa metal alkyls and dialkyl metal halides having 1 to about 20 carbon atoms per alkyl radical. More preferably, the reducing agent is a trialkylaluminum compound having 1 to about 6 carbon atoms per alkyl radical. Other reducing agents which can be used herein are disclosed in Stevens et al., U.S. Pat. No. 3,787,384, column 4, line 45 to column 5, line 12 and in Strobel et al., U.S. Pat. No. 4,148,754, column 4, line 56 to column 5, line 59, the entire contents of both of which are incorporated herein by reference. Particularly preferred reducing agents are metal alkyl or hydride derivatives of a metal selected from Groups Ia, IIa and IIIa of the Periodic Table of the Elements, such as n-butyl lithium, sec-butyl lithium, n-hexyl lithium, phenyl-lithium, triethylaluminum, tri-isobutylaluminum, trimethyl-aluminum, diethylaluminum hydride and dibutylmagnesium.

[0130] The molar ratio of the metal derived from the reducing agent to the metal derived from the transition metal compound will vary for the selected combinations of the reducing agent and the transition metal compound, but in general it is at least about 1:1, preferably at least about 1.5:1, more preferably at least about 2:1, and even more preferably at least about 2.5:1. The molar ratio of the metal derived from the reducing agent to the metal derived from the transition metal compound will vary for the selected combinations of the reducing agent and the transition metal compound, but in general it is at most about 12:1, preferably at most about 8:1, more preferably at most about 7:1, and even more preferably at most about 6:1. It will be apparent to those skilled in the art that the optimal ratios will vary depending upon the transition metal and the organometallic agent used, e.g., for the trialkylaluminum/nickel(II) systems, the preferred aluminum: nickel molar ratio is about 2.5:1 to about 4:1, for the trialkylaluminum/cobalt(II) systems, the preferred aluminum: cobalt molar ratio is about 3:1 to about 4:1, and for the trialkylaluminum/titanium(IV) alkoxides systems, the preferred aluminum: titanium molar ratio is about 3:1 to about 6:1.

[0131] The mode of addition and the ratio of the reducing agent to the transition metal compound are important in the production of the novel hydrogenation catalyst having superior selectivity, efficiency and stability, as compared to prior art catalytic systems. During the synthesis of the catalysts it is preferred to maintain the molar ratio of the reactants used to synthesize the catalyst substantially constant. This can be done either by the addition of the reducing agent, as rapidly as possible, to a solution of the transition metal compound, or by a substantially simultaneous addition of the separate streams of the reducing agent and the transition metal compound to a catalyst synthesis vessel in such a manner that the selected molar ratios of the metal of the reducing agent to the metal of the transition metal compound are maintained substantially constant throughout substantially the entire time of addition of the two compounds. The time required for the addition must be such that excessive pressure and heat build-up are avoided, i.e., the temperature should not exceed about 80 EC and the pressure should not exceed the safe pressure limit of the catalyst synthesis vessel.

[0132] In a preferred embodiment, the reducing agent and the transition metal compound are added substantially simultaneously to the catalyst synthesis vessel in such a manner that the selected molar ratio of the reducing agent to the transition metal compound is maintained substantially constant during substantially the entire time of the addition of the two compounds. This preferred embodiment permits the control of the exothermic reaction so that the heat build-up is not excessive, and the rate of gas production during the catalyst synthesis is also non excessive—accordingly, the gas build-up is relatively slow. In this embodiment, carried out with or without a solvent diluent, the rate of addition of the catalyst components is adjusted to maintain the synthesis reaction temperature at or below about 80 EC, which promotes the formation of the selective hydrogenation catalyst. Furthermore, the selected molar ratios of the metal of the reducing agent to the metal of the transition metal compound are maintained substantially constant throughout the entire duration of the catalyst preparation when the simultaneous mixing technique of this embodiment is employed.

[0133] In another embodiment, the catalyst is formed by the addition of the reducing agent to the transition metal compound. In this embodiment, the timing and the order of addition of the two reactants is important to obtain the hydrogenation catalyst having superior selectivity, efficiency and stability. Thus, in this embodiment, it is important to add the reducing agent to the transition metal compound in that order in as short a time period as practically possible. In this embodiment, the time allotted for the addition of the reducing agent to the transition metal compound is critical for the production of the novel catalyst. The term “as short a time period as practically possible” means that the time of addition is as rapid as possible, such that the reaction temperature is not higher than about 80 EC and the reaction pressure does not exceed the safe pressure limit of the catalyst synthesis vessel. As will be apparent to those skilled in the art, that time will vary for each synthesis and will depend on such factors as the types of the reducing agents, the transition metal compounds and the solvents used in the synthesis, as well as the relative amounts thereof, and the type of the catalyst synthesis vessel used. For purposes of illustration, a solution of about 15 mL of triethylaluminum in hexane should be added to a solution of nickel(II) octoate in mineral spirits in about 10-30 seconds. Generally, the addition of the reducing agent to the transition metal compound should be carried out in about 5 seconds (sec) to about 5 minutes (min), depending on the quantities of the reagents used. If the time period during which the reducing agent is added to the transition metal compound is prolonged, e.g., more than 15 minutes, the synthesized catalyst is less selective, less stable, and may be heterogeneous.

[0134] In the nonpreferred embodiment wherein the reducing agent is added as rapidly as possible to the transition metal compound, it is also important to add the reducing agent to the transition metal compound in the aforementioned sequence to obtain the novel catalyst. The reversal of the addition sequence, i.e., the addition of the transition metal compound to the reducing agent, or the respective solutions thereof, is detrimental to the stability, selectivity, activity, and homogeneity of the catalyst and is, therefore, undesirable.

[0135] In all embodiments of the hydrogenation catalyst synthesis, it is preferred to use solutions of the reducing agent and the transition metal compound in suitable solvents, such as hydrocarbon solvents, e.g., cyclohexane, hexane, pentane, heptane, benzene, toluene, or mineral oils. The solvents used to prepare the solutions of the reducing agent and of the transition metal compound may be the same or different, but if they are different, they must be compatible with each other so that the solutions of the reducing agent and the transition metal compound are preferably fully soluble in each other.

[0136] The hydrogenation process comprises contacting the unsaturated polymer to be hydrogenated with an amount of the catalyst solution containing at least about 0.1, preferably at least about 0.2, and at most about 0.5, preferably at most about 0.3 mole percent of the transition metal based on moles of the polymer unsaturation. The hydrogen partial pressure is generally from at least about 5 psig, preferably at least about 10 psig, and at most about several hundred psig, preferably at most about 100 psig. The temperature of the hydrogenation reaction mixture is generally at least about 0° C., preferably at least about 25° C., and more preferably at least about 30° C. The temperature of the hydrogenation reaction mixture is generally at most about 150° C., preferably at most about 80° C., and more preferably at most about 60° C., since higher temperatures may lead to catalyst deactivation. The length of the hydrogenation reaction may be as short as 30 minutes and, as will be apparent to those skilled in the art, depends to a great extent on the actual reaction conditions employed. The hydrogenation process may be monitored by any conventional means, e.g., infra-red spectroscopy, hydrogen flow rate, total hydrogen consumption, or any combination thereof.

[0137] Upon completion of the hydrogenation process, unreacted hydrogen is either vented or consumed by the introduction of the appropriate amount of an unsaturated material, such as 1-hexene, which is converted to an inert hydrocarbon, e.g., hexane. Subsequently, the catalyst is removed from the resulting polymer solution by any suitable means, selected depending on the particular process and polymer. For a low molecular weight material, for example, catalyst needs space residue removal may consist of a treatment of the solution with an oxidant, such as air, and subsequent treatment with ammonia and optionally methanol in amounts equal to the molar amount of the metals (i.e., the sum of the transition metal and the metal of the reducing agent) present in the hydrogenation catalyst to yield the catalyst residues as a filterable precipitate, which is filtered off. The solvent may then be removed by any conventional methods, such as vacuum stripping, to yield the product polymer as a clear, colorless fluid.

[0138] Alternatively, and in a preferred embodiment, upon completion of the hydrogenation reaction, the mixture is treated with ammonia in the molar amount about equal to that of the metals (i.e., the sum of the transition metal and the metal of the reducing agent) and aqueous hydrogen peroxide, in the molar amount equal to about one half to about one, preferably one half, of the amount of the metals. Other levels of the ammonia and peroxide are also operative, but those specified above are particularly preferred. In this method, a precipitate forms, which may be filtered off as described above.

[0139] In yet another alternative method, the catalyst may be removed by extraction with an aqueous mineral acid, such as sulfuric, phosphoric, or hydrochloric acid, followed by washing with distilled water. A small amount of a material commonly used as an aid in removing transition metal-based catalysts, such as a commercially available high molecular weight diamine, e.g., Jeffamine D-2000 from Huntsman, may be added to aid in phase separation and catalyst removal during the extractions. The resultant polymer solution is then dried over a drying agent, such as magnesium sulfate, separated from the drying agent and the solvent is then separated by any conventional methods, such as vacuum stripping, to yield a polymer as a clear fluid. Other methods of polymer isolation, such as steam or alcohol flocculation, may be employed depending upon the hydrogenated polymer properties.

[0140] After hydrogenation and purification is complete, the polymer can be functionalized and used in the explosive emulsion compositions of the invention.

[0141] Functionalization of the Polymers

[0142] The unsaturated portion of the block polymers of this invention can be chemically modified or functionalized to provide benefits which enhance the activity and viscosity improving qualities of the materials of the invention. Such benefits may be obtained through methods similar to those employed for the modification of existing commercial materials, such as polyisobutylene or EPDM.

[0143] Following the selective hydrogenation step, the remaining sites of unsaturation may be chemically modified. Such methods include reacting the unsaturated groups in the polymer with any of various reagents to produce functional groups, such as halogen, hydroxyl, epoxy, sulfonic acid, mercapto, acrylate or carboxyl groups. Functionalization methods are well known in the art, as detailed in Advance Organic Chemistry, 4th edition, Jerry March, John Wiley and Son, NY 1992, pp. 758-761, 766-767, 794, 814-816, 823, 825-829, 831, incorporated herein by reference.

[0144] A preferred chemical modification method involves reaction of the polymer with an unsaturated carboxylic acid and/or derivatives, such as acrylic acid, maleic acid, fumaric acid, maleic anhydride, methacrylic acid, esters of these acids, and the like. Most preferably, maleic anhydride is used for the chemical modification of unsaturation. Numerous methods are known for the chemical modification of polyisobutylene and EPDM via the ene reaction, as disclosed in U.S. Pat. Nos. 4,234,435 and 4,919,128, incorporated herein by reference. Methods are also known for the reaction of maleic anhydride with EPDM via a radical reaction in the presence of a radical initiator. These methods can be adapted to incorporate the unsaturated carboxylic acid derivatives into the polymeric emulsifiers of the invention.

[0145] Subsequent to the acylation reaction (or other suitable chemical modifications as outlined above), the chemically modified polymers may be reacted with a Lewis base, such as a monoamine, a polyamine, a polyhydroxy compound, a reactive polyether, or a combination thereof. Amines which are useful for this modification reaction are characterized by the presence of at least one primary (i.e., H2N—) or secondary (i.e., HRN—) amino group. The monoamines and polyamines can be aliphatic amines, cycloaliphatic amines, heterocyclic amines, aromatic amines, or hydroxyamines. Preferably, the polyamines contain only one primary or secondary amine, with the remaining amines being tertiary (i.e., NR1R2R3, wherein R1, R2 and R3 are not equal to H) or aromatic amines. The amination can be accomplished by heating the maleic anhydride-modified polymerized conjugated diene to about 150° C. in the presence of the amine, followed by stripping off the water. A useful monoamine is ethanol amine. Useful polyamines include aminopropylmorpholine and tetraethylenepentamine. Useful polyhydroxy compounds include ethylene glycol and pentaerythritol. Useful reactive polyethers include polyethers which contain hydroxy or amino groups which will react with the modified polymer, such as polyethylene glycol monoalcohol.

[0146] In a preferred functionalization of polymerized conjugated diene copolymer, the selectively hydrogenated copolymer is functionalized with functional groups selected from among halogens, epoxides, sulfonic acids, mercapto acid and/or derivatives and carboxylic acid derivatives, and can be subsequently modified further by reacting with a monoamine, a polyamine, a polyhydroxy compound, a reactive polyether, or a combination thereof.

[0147] The ene reaction of maleic anhydride with materials of the invention can be performed on neat polymers or solutions of the polymers in light mineral oil or polyalphaolefin at temperatures of from about 150° C. to about 250° C., typically under an inert atmosphere. Such modification of the polymers of any embodiments of our invention occurs readily, since the residual isoprene unsaturation, primarily of the 3,4-type, illustrated above, is known to be more reactive with maleic anhydride than are the internal bonds found in EPDM.

[0148] Maleic modification may be used in the present invention. The activity of the maleic modified emulsifiers of the present invention is related to the degree of maleation, measured by acid number, their molecular weights and composition.

[0149] In addition, the selectively hydrogenated polymer may be functionalized by other methods which enhance the activity, including but not limited to: grafting of heteroatom-containing olefins; formation of Mannich base condensates at the sites of unsaturation; hydroformylation/reductive amination; addition of nitrosamines or nitrosophenols; lithiation followed by reaction with electrophilic compounds capable of displacement or addition reactions to provide carboxy, nitrilo, or amino groups; 1,3-dipolar addition of nitrile oxides, nitrones, and the like; light catalyzed cycloaddition of activated olefins; and light catalyzed insertion reactions.

[0150] Grafting of heteroatom-containing olefins may be accomplished by reacting the polymer with a vinyl monomer in the presence of a free radical initiator, such as t-butylperoxybenzoate, to directly form a dispersant molecule. Nitrogen and/or oxygen-containing vinyl monomers, such as vinylimidazole and maleic anhydride, may be used. The number of vinyl monomers appended to the polymer in this fashion can be from 1 to 20 or more per 10,000 molecular weight.

[0151] Suitable vinyl monomers are disclosed in U.S. Pat. Nos. 5,663,126; 5,140,075; 5,128,086; 4,146,489; 4,092,255; and 4,810,754, incorporated herein by reference.

[0152] Suitable free radical initiators are disclosed in U.S. Pat. Nos. 5,663,126 and 4,146,489, incorporated herein by reference.

[0153] Any conventional grafting method may be used. For example, the grafting may be performed by dissolving the polymer in a solvent, preferably a hydrocarbon solvent, adding a free radical initiator and a nitrogen and/or oxygen-containing vinyl monomer. The mixture is then heated to obtain a grafted polymer. The grafted polymer may be isolated by conventional methods. For example, the graft copolymer may be converted to a concentrate by evaporative distillation of solvent, non-reacted vinyl monomer, and reaction by-products. For ease of handling, a mineral oil diluent may be added before or after the evaporative procedure.

[0154] The grafted polymer may be further reacted with an amine, preferably containing at least one —NH group. Suitable amines include monoamines, polyamines, amino alcohols, amino acids or derivatives thereof, and amino terminated polyethers.

[0155] Alternatively, the selectively hydrogenated polymer may be functionalized by aminomethylation or hydroformylation followed by reductive amination. The polymer is reacted with carbon monoxide and hydrogen, in the presence of a transition metal catalyst to provide carbonyl derivatives of the polymer. The functionalized polymer is subsequently modified by reductive amination. Useful amines include, but are not limited to, monoamines, polyamines, amino alcohols, amino acids or derivatives thereof, and amino terminated polyethers with the proviso that the amine has at least one primary or secondary amino group. The number of suitable reaction sites per molecule can be from 1 to 20 or more per 10,000 molecular weight.

[0156] Aminomethylation and hydroformylation followed by reductive amination are described in U.S. Pat. Nos. 3,311,598; 3,438,757; 4,832,702; and 5,691,422, incorporated herein by reference.

[0157] The above description illustrates only some of the potentially valuable chemical modification of the polymers of this invention. The polymers of this invention provide a means for a wide variety of chemical modifications at selected sites in the polymer, e.g., at select ends, in the middle, or randomly, thereby presenting the opportunity to prepare materials previously impossible because of the lack of availability of such polymers. Some examples of well known chemical reactions which can be performed on polymers of this invention are found in E. M. Fettes, “Chemical Reactions of Polymers”, High Polymers, Vol. 19, John Wiley, New York, (1964), incorporated herein by reference.

[0158] Explosive Emulsions

[0159] The present invention relates to explosive emulsion compositions comprising oil, oxidizer, water and emulsifier. Explosive emulsion compositions containing copolymers of isoprene and/or butadiene and/or styrene which have been functionalized with, for example, carboxyl containing and/or amine containing functional groups as emulsifier, exhibit enhanced emulsification at lower concentrations.

[0160] Explosive emulsion compositions containing copolymers of isoprene and/or butadiene and/or styrene which have been functionalized with carboxyl containing and/or amine containing functional groups (modified copolymers) exhibit enhanced stability. Depending on molecular weight, polymer block structure, and type and degree of functionality, it is possible to enhance the effectiveness of the materials as emulsifiers for aqueous explosive formulations.

[0161] The composition and molecular weight of the copolymers of the present invention may be varied allowing for varying viscosity and solubility parameters depending on the requirements of a specific formulation. Additionally, selective hydrogenation provides an added benefit by providing materials that may be regiospecifically chemically modified with various polar groups. In particular, the placement of carboxyl groups derived from maleic anhydride and/or the subsequent modification with hydroxyl or amine-containing compounds provides for materials that display enhanced levels of emulsion stability. For example, it is believed that the use of minimal levels of an isoprene-butadiene copolymer with the appropriate molecular weight and level of functionality (as measured by total acid number (TAN) or total base number (TBN), depending on functional group type), is useful in the preparation of emulsions of ammonium nitrate, water, and a light hydrocarbon oil that display extended periods of room temperature stability.

[0162] The activity of the emulsifier determines the effectiveness of emulsification of the oxidizer and the oil. The activity of the emulsifiers of the present invention is affected by the shape of the polymer molecule, the type of monomer blocks and their position within the molecule. Effective emulsification is one of the main factors influencing the performance of the resulting explosive emulsion. The emulsifier not only aids the process of droplet subdivision and dispersion in the oil continuous phase by reducing the surface tension, but also reduces the coalescence rate by coating the surface of the droplet with a layer of emulsifier molecules. This latter property is critical in reducing the rate of detonation-impairing crystallization of the emulsion explosive. In some cases, the emulsifier is also a crystal habit modifier, limiting the formation and growth of crystals within the aqueous oxidizer solution.

[0163] The amount of emulsifier employed in the present invention is at least about 0.05 wt. % of the total explosive emulsion composition and preferably at least about 0.10 wt. % of the total explosive emulsion composition. The amount of emulsifier employed in the process of the present invention is at most about 2.0 wt. % of the total explosive emulsion composition, preferably at most about 1.5 wt. % of the total explosive emulsion composition and more preferably at most about 1.0 wt. % of the total explosive emulsion composition.

[0164] The oxidizer generally comprises oxidizing salts dissolved in water. Such salts include ammonium, alkali metal and alkaline earth nitrates, chlorates, and perchlorates and mixtures of these salts. In one embodiment, inorganic oxidizer salt comprises principally ammonium nitrate. The pH, if below 5.5, may be raised by the addition of concentrated ammonium hydroxide.

[0165] The amount of oxidizing salt is generally at least about 40% by weight of the total explosive emulsion composition, preferably at least about 50% by weight of the total explosive emulsion composition and more preferably at least about 55% by weight of the total explosive emulsion composition The amount of oxidizing salt is generally at most about 95% by weight of the total explosive emulsion composition, preferably at most about 90% by weight of the total explosive emulsion composition and more preferably at most about 85% by weight of the total explosive emulsion composition

[0166] The amount of water is generally at least about 5% by weight of the total explosive emulsion composition, preferably at least about 10% by weight of the total explosive emulsion composition and more preferably at least about 15% by weight of the total explosive emulsion composition. The amount of water is generally at most about 55% by weight of the total explosive emulsion composition, preferably at most about 50% by weight of the total explosive emulsion composition and more preferably at most about 30% by weight of the total explosive emulsion composition.

[0167] The oil is the continuous phase of the emulsion, and acts as the carbonaceous fuel in the explosive emulsion. The carbonaceous fuel that is useful in the emulsions of the invention can include most hydrocarbons, for example, paraffinic, olefinic, naphthenic, aromatic, saturated or unsaturated hydrocarbons, and is typically in the form of an oil or a wax or a mixture thereof. In general, the carbonaceous fuel is a water-immiscible, emulsifiable hydrocarbon that is either liquid or liquefiable at a temperature of up to about 95° C., and preferably between about 40° C. and about 75° C. Oils from a variety of sources, including natural and synthetic oils and mixtures thereof can be used. The oil that is useful in the inventive emulsions can be a hydrocarbon oil having viscosity values from about 20 SUS (Saybolt Universal Seconds) at 100° F. to about 2500 SUS at 100° F. Mineral oils having lubricating viscosities (e.g. SAE 5-90 grade) can be used.

[0168] Examples of useful oils include a white mineral oil available from Witco Chemical Company under the trade designation KAYDOL (CAS No. 8012-95-1); a white mineral oil available from Shell under the trade designation ONDINA (CAS No.8012-95-1); and a mineral oil available from Pennzoil under the trade designation N-750-HT. Diesel fuel (e.g., Grade No. 2-D as specified in ASTM D-975) can be used as the oil.

[0169] Natural oils include animal oils and vegetable oils (e.g., castor oil, lard oil) as well as solvent-refined or acid-refined mineral lubricating oils of the paraffinic, naphthenic, or mixed paraffin-naphthenic types. Oils of lubricating viscosity derived from coal or shale are also useful. Synthetic lubricating oils may be used. These include hydrocarbon oils and halo-substituted hydrocarbon oils such as polymerized and interpolymerized olefins (e.g., polybutylenes, polypropylenes, propyleneisobutylene copolymers, chlorinated polybutylenes, etc.); alkyl benzenes (e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di-(2-ethylhexyl)benzenes, etc.); polyphenols (e.g., biphenyls, terphenyls, etc.); and the like. Alkylene oxide polymers and interpolymers and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, etc., constitute another class of known synthetic lubricating oils. These are exemplified by the oils prepared through polymerization of ethylene oxide or propylene oxide, the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g., methylpolyisopropylene glycol ether having an average molecular weight of about 1000, diphenyl ether of polyethylene glycol having a molecular weight of about 500-1000, diethyl ether of polypropylene glycol having a molecular weight of about 1000-1500, etc.) or mono- and poly-carboxylic esters thereof, for example, the acetic acid esters, mixed C3-C8 fatty acid esters, or the C13 Oxo acid diester of tetraethylene glycol.

[0170] Another suitable class of synthetic lubricating oils comprises the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, etc.) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, pentaerythritol, etc.). Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl)sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethyl-hexanoic acid, and the like.

[0171] Unrefined, refined and re-refined oils (and mixtures of each with each other) of the type disclosed hereinabove can be used in the explosive emulsions of the present invention. Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment. For example, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from distillation or ester oil obtained directly from an esterification process and used without further treatment would be an unrefined oil.

[0172] Refined oils are similar to the unrefined oils except that they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques are known to those of skill in the art such as solvent extraction, acid or base extraction, filtration, percolation, etc. Re-refined oils are obtained by processes similar to those used to obtain refined oils applied to refined oils which have been already used in service. Such re-refined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques directed to removal of spent additives and oil breakdown products.

[0173] It may be desirable to include small amounts of silicon oils as additives in the oil These oils tend to make the composition more resistant to moisture in the environment. Useful silicon-based oils include materials such as the polyalkyl-, polyaryl-, polyalkoxy-, or polyaryloxy-siloxanes. For example the following specific materials may be used: hexyl-(4-methyl-2-pentoxy)di-siloxane, poly(methyl)-siloxanes, poly(methylphenyl)siloxanes.

[0174] The oil may contain any wax having melting point of at least about 25° C. and generally below 90° C., such as petrolatum wax, microcrystalline wax, and paraffin wax, mineral waxes such as ozocerite and montan wax, animal waxes such as spermaceti wax, and insect waxes such as beeswax and Chinese wax. Useful waxes include waxes identified by the trade designation MOBILWAX 57 which is available from ExxonMobil Corporation; D02764 which is a blended wax available from Astor Chemical Ltd.; and VYBAR which is available from Petrolite Corporation. Preferred waxes are blends of microcrystalline waxes and paraffin.

[0175] The oil is generally present at a level of at least about 4% by weight of the total explosive emulsion composition, preferably at least about 6% by weight of the total explosive emulsion composition and more preferably at least about 7% by weight of the total explosive emulsion composition. The oil is generally present at a level of at most about 30% by weight of the total explosive emulsion composition, preferably at most about 20% by weight of the total explosive emulsion composition and more preferably at most about 10% by weight based on the total weight of the total explosive emulsion composition.

[0176] Explosive emulsions typically contain other additives such as sensitizing components, oxygen-supplying salts, particulate light metals, particulate solid explosives, soluble and partly soluble self-explosives, explosive oils and the like for purposes of augmenting the strength and sensitivity or decreasing the cost of the emulsion.

[0177] The sensitizing components are distributed substantially homogeneously throughout the emulsions. These sensitizing components are preferably occluded gas bubbles which may be introduced in the form of glass or resin microspheres or other gas-containing particulate materials. Alternatively, gas bubbles may be generated in situ by adding to the composition and distributing therein a gas-generating material such as, for example, an aqueous solution of sodium nitrite. Other suitable sensitizing components which may be employed alone or in addition to the occluded or in-situ generated gas bubbles include insoluble particulate solid self-explosives such as, for example, grained or flaked TNT, DNT, RDX and the like, and water-soluble and/or hydrocarbon-soluble organic sensitizers such as, for example, amine nitrates, alkanolamine nitrates, hydroxyalkyl nitrates, and the like. The explosive emulsions of the present invention may be formulated for a wide range of applications. Any combination of sensitizing components may be selected in order to provide an explosive composition of virtually any desired density, weight-strength, or critical diameter.

[0178] Optional additional materials may be incorporated in the explosive emulsions of the invention in order to further improve sensitivity, density, strength, rheology and cost of the final explosive. Typical of materials found useful as optional additives include, for example, emulsion promotion agents such as highly chlorinated paraffinic hydrocarbons, particulate oxygen-supplying salts such as prilled ammonium nitrate, calcium nitrate, perchlorates, and the like, particulate metal fuels such as aluminum, silicon and the like, particulate non-metal fuels such as sulfur, gilsonite and the like, particulate inert materials such as sodium chloride, barium sulphate and the like, water phase thickeners such as guar gum, polyacrylamide, carboxymethyl or ethyl cellulose, biopolymers, starches, and the like, buffers or pH controllers such as sodium borate, zinc nitrate and the like, and additives of common use in the explosives art.

[0179] The explosive emulsions may be formed by methods well known to those skilled in the art. One common method is to mix the emulsifier with the oil to form an emulsifiable oil. The salts and other water soluble components, if any, are mixed with water at an elevated temperature sufficient to cause the formation of a solution. The oil, water and oxidizer are brought together and mixed at a low shear rate to form a preemulsion and then at a higher rate to form the final emulsion. Suspended components such as sensitizers, added fuels, and added oxidizers may be added after the emulsion is formed.

EXAMPLES

[0180] The following examples are intended to assist in a further understanding of the invention. The particular materials and conditions employed are intended to be further illustrative of the invention and are not limiting upon the reasonable scope thereof.

[0181] In all of the following examples, the experimental polymerization and chemical modification work is performed with dried reactors and equipment and under strictly anaerobic conditions. All % are % by weight. Extreme care must be used to exclude air, moisture and other impurities capable of interfering with the delicate chemical balance involved in the synthesis of the polymers of this invention, as will be apparent to those skilled in the art.

[0182] No gassing agents or micro bubbles are incorporated in the emulsion used for testing the emulsifier performance. Performance is measured by the ability to form a stable emulsion.

Example I

Preparation of Polymer Precursor Backbones

[0183] Using the procedure described in Example VII of U.S. Pat. No. 5,633,415, incorporated herein by reference, an isoprene-styrene-butadiene triblock polymer having a number average molecular weight of about 10,000 is prepared. Twenty five percent (25%) of the isoprene in Example VII is replaced with styrene.

Example II

Selective Hydrogenation of the Polymer of Example I

[0184] The polymer solution of Example I is subjected to a selective hydrogenation procedure using a catalyst prepared by diethylaluminum ethoxide and cobalt octoate (3.5 to 1 molar ratio) and following general procedures as described in Example VIII of U.S. Pat. No. 5,633,415, incorporated herein by reference. The extent of hydrogenation is followed by Fourier Transfer Infrared (FTIR) and is continued until no absorption remains at 910 cm−1 and 990 cm−1(-1,2 polybutadiene structure) and essentially no residual trans double bonds are present as seen by disappearance of the 968 cm−1 absorption. The FTIR analysis of the polymers at the end of the selective hydrogenation typically indicates 0 to 10 trans polybutadiene double bonds and 50 to 100 vinylidene (-3,4 polyisoprene) double bonds remain-normalized to 100,000 molecular weight polymer chain. The polymer of Example I has 0 to 1.5 trans double bonds and 7.5 to 15 vinylidene double bonds (for subsequent functionalization).

[0185] The hydrogenation catalyst is removed by washing, as described in U.S. Pat. No. 5,633,415, or by a filtration procedure preceded by precipitation of the catalyst with essentially stoichiometric levels of acetic acid and hydrogen peroxide. After catalyst removal, the solvent is removed under reduced pressure to give the polymer.

Example III

Maleic Modification of the Polymer of Example II

[0186] The polymer of Example II, dissolved in a diluent oil, such as low viscosity mineral oil or PAO fluid, is reacted with maleic anhydride to give an acid number (based on neat polymer) of approximately 45. The reaction is performed at approximately 180° C. and is monitored by FTIR and/or acid number titration of stripped samples. The time required for reaction is typically 3 to 20 hours. After reaction, any residual maleic anhydride is removed by vacuum stripping of the reaction mixture to form the emulsifier.

Example IV

Explosive Emulsion Containing the Chemically Modified Polymer of Example III

[0187] Preparation of Oxidizer Solution:

[0188] Six hundred sixty (660) grams of ammonium nitrate, commercially obtained from Aldrich Chemical Company, 150 grams of calcium nitrate and 190 grams of water are charged into a one-gallon glass jar with a tight fitting lid. The jar is heated to dissolve the mixture. The solution is stored in an oven set at 85° C.

[0189] Emulsion Procedure:

[0190] The emulsifier (7 grams) is dissolved in a mineral oil (55.9 grams) and diesel fuel oil (55.9 grams) mixture to form a fuel oil solution (118.8 grams). The fuel oil is charged to a container. The stirring shaft is placed into the container with the impeller blade just clearing the bottom of the container. The hot oxidizer solution is poured into the fuel oil solution under slow agitation until an emulsion is formed. The mixing speed is increased to about 1800 rpm and stirred for about two minutes to refine the emulsion. The emulsion has the following composition: 1 Ammonium nitrate 58.99% by weight Calcium nitrate 13.40% by weight Emulsifier 0.63% by weight (as prepared in Example III) Diesel fuel 5.00% by weight Mineral oil 5.00% by weight Water 16.98% by weight Viscosity 23,900 centipoise Crystal content 0%

[0191] Performance Evaluation

[0192] Once the emulsion is prepared, the stability is measured using the following tests:

[0193] Gear pump test (to measure shear stability)

[0194] Temperature cycle test (to measure long term stability)

[0195] During the gear pump test which involves high shear, the emulsion is passed to a gear pump set at 200 rpm. The viscosity and crystal content are qualitatively measured by visual evaluation after one, three and six gear pump passes under polarized light using a microscope. 2 No. of gear pump passes Viscosity (centipoise) % Crystallization 1 30,800 10 3 49,300 20 6 75,800 20

[0196] The temperature cycle test requires storing the emulsion in a freezer set at −25° C. for 24 hours. The emulsion is then removed from the freezer and placed in an oven set at 40° C. for another 24 hours. The emulsion is then cooled to room temperature and the crystal content measured by looking at the emulsion under polarized light using a microscope. The procedure is repeated ten times. Less than 10% crystallization indicates a stable emulsion. 3 Run No. % Crystallization 1 <10 2 <10 3 <10 4 <10 5 <10 6 <10 7 <10 8 <10 9 <10 10  <10

[0197] In general, enhanced performance is observed in several cases. In particular, it is quite clear that variation of functional type and amount, molecular weight, and block structure all play important roles in the final performance of explosive emulsions. The level of control that is available to the isoprene-styrene butadiene-based system is not available to conventional chemistry based on polyisobutylene and the like.

[0198] Thus, while there have been described what are presently believed to be the preferred embodiments of the present invention, those skilled in the art will realize that other and further embodiments can be made without departing from the spirit of the invention, and it is intended to include all such further modifications and changes as come within the true scope of the claims set forth herein.

Claims

1. An explosive emulsion composition comprising: a copolymer of a first conjugated diene and a second conjugated diene, wherein:

said first conjugated diene comprises at least one relatively more substituted conjugated diene having at least five carbon atoms and the formula:

16

wherein R1—R6 are each independently hydrogen or a hydrocarbyl group, provided that at least one of R1—R6 is a hydrocarbyl group, provided that after polymerization, the unsaturation of the polymerized conjugated diene of formula (1) has the formula:

17

wherein RI, RII, RIII and RIV are each independently hydrogen or a hydrocarbyl group, provided that either both RI and RII are hydrocarbyl groups or both RIII and RIV are hydrocarbyl groups; and

said second conjugated diene comprises at least one relatively less substituted conjugated diene different from the first conjugated diene and having at least four carbon atoms and the formula:

18

wherein R7-R12 are each independently hydrogen or a hydrocarbyl group, provided that after polymerization, the unsaturation of the polymerized conjugated diene of formula (3) has the formula:

19

wherein RV, RVI, RVII and RVIII are each independently hydrogen or a hydrocarbyl group, provided that one of RV or RVI is hydrogen, one of RVII or RVIII is hydrogen, and at least one of RV, RVI, RVII and RVIII is a hydrocarbyl group; and

wherein said copolymer has been functionalized by a method comprising:

selectively hydrogenating said copolymer to provide a selectively hydrogenated copolymer; and

functionalizing said selectively hydrogenated copolymer to provide a functionalized copolymer having at least one polar functional group.

2. The explosive emulsion composition of claim 1, wherein said copolymer is in an amount in the range of from 0.05 to 2.0% by weight based on the total weight of explosive emulsion composition.

3. The explosive emulsion composition of claim 1, wherein said copolymer is in an amount in the range of from 0.1 to 1.5% by weight based on the total weight of explosive emulsion composition.

4. The explosive emulsion composition of claim 1, wherein said copolymer is in an amount in the range of from 0.1 to 1% by weight based on the total weight of explosive emulsion composition.

5. The explosive emulsion composition of claim 1, further comprising oxidizer in an amount in the range of 40 to 95% by weight based on the total weight of the explosive emulsion composition.

6. The explosive emulsion composition of claim 5, wherein said oxidizer is ammonium nitrate.

7. The explosive emulsion composition of claim 1, further comprising water in an amount in the range of 5 to 50% by weight based on the total weight of the explosive emulsion composition.

8. The explosive emulsion composition of claim 1, further comprising oil in an amount in the range of 4 to 30% by weight based on the total weight of the explosive emulsion composition.

9. The explosive emulsion composition of claim 1, wherein said first and second conjugated dienes are polymerized as a block copolymer comprising at least two alternating blocks:

(I)x-(B)y or (B)y—(I)x

wherein:

the block (I) comprises at least one polymerized conjugated diene of formula (1);

the block (B) comprises at least one polymerized conjugated diene of formula (3);

x is the number of polymerized monomer units in block (I) and is at least 1, and y is the number of polymerized monomer units in block (B) and is at least 25.

10. The explosive emulsion composition of claim 1, wherein said first conjugated diene is included in said polymer in an amount of from 1% to about 25% wt.; and said second conjugated diene is included in said polymer in an amount of from 75% wt. to 99% wt.

11. The explosive emulsion composition of claim 1, wherein after the selectively hydrogenating step, the Iodine Number for residual unsaturation of formula (2) is from 50% to 100% of the Iodine Number prior to the selectively hydrogenating step.

12. The explosive emulsion composition of claim 1, wherein after the selectively hydrogenating step, the Iodine Number for residual unsaturation of formula (4) is from 0% to 10% of Iodine Number prior to the selectively hydrogenating step.

13. The explosive emulsion composition of claim 1, wherein the conjugated diene of formula (1) comprises isoprene and the conjugated diene of formula (3) comprises 1,3-butadiene.

14. The explosive emulsion composition of claim 13, wherein each of the (B) blocks has from 30% to 90% of 1,2-subunits.

15. The explosive emulsion composition of claim 1, wherein said functionalizing step provides a functionalized polymer having at least one functional group selected from the group consisting of halogen groups, hydroxyl groups, epoxy groups, sulfonic acid groups, mercapto groups, carboxylic acid derivative groups, and mixtures thereof.

16. The explosive emulsion composition of claim 15, wherein said carboxylic acid derivative groups are derived from maleic anhydride.

17. The explosive emulsion composition of claim 1, wherein said functionalized copolymer is modified by reaction with a Lewis base selected from the group consisting of a monoamine, polyamine, polyhydroxy compound, reactive polyether, or a combination thereof.

18. The explosive emulsion composition of claim 17, wherein said polyamine comprises an aminopropylmorpholine.

19. An explosive emulsion composition comprising:

a copolymer of a first conjugated diene, a second conjugated diene and an aryl-substituted olefin, wherein:

said first conjugated diene comprises at least one relatively more substituted conjugated diene having at least five carbon atoms and the formula:

20

wherein R1-R6 are each independently hydrogen or a hydrocarbyl group, provided that at least one of R1-R6 is a hydrocarbyl group, provided that after polymerization, the unsaturation of the polymerized conjugated diene of formula (1) has the formula:

21

wherein RI, RII, RIII and RIV are each independently hydrogen or a hydrocarbyl group, provided that either both RI and RII are hydrocarbyl groups or both RIII and RIV are hydrocarbyl groups; and

said second conjugated diene comprises at least one relatively less substituted conjugated diene different from the first conjugated diene and having at least four carbon atoms and the formula:

22

wherein R7-R12 are each independently hydrogen or a hydrocarbyl group, provided that after polymerization, the unsaturation of the polymerized conjugated diene of formula (3) has the formula:

23

wherein RV, RVI, RVII and RVIII are each independently hydrogen or a hydrocarbyl group, provided that one of RV or RVI is hydrogen, one of RVII or RVIII is hydrogen, and at least one of RV, RVI, RVII and RVIII is a hydrocarbyl group; and

wherein said copolymer has been functionalized by a method comprising:

selectively hydrogenating said copolymer to provide a selectively hydrogenated copolymer; and

functionalizing said selectively hydrogenated copolymer to provide a functionalized copolymer having at least one polar functional group.

20. The explosive emulsion composition of claim 19, wherein said aryl-substituted olefin is selected from the group consisting of styrene, alkylated styrene, vinyl naphthalene and alkylated vinyl naphthalene.

21. The explosive emulsion composition of claim 20, wherein said aryl-substituted olefin is styrene.

22. The explosive emulsion composition of claim 19, wherein said functionalizing step provides a functionalized polymer having at least one functional group selected from the group consisting of halogen groups, hydroxyl groups, epoxy groups, sulfonic acid groups, mercapto groups, carboxylic acid derivative groups, and mixtures thereof.

23. The explosive emulsion composition of claim 19, wherein said carboxylic acid derivative groups comprise maleic anhydride.

24. The explosive emulsion composition of claim 19, wherein said first and second conjugated dienes are polymerized as a block copolymer comprising at least two alternating blocks:

(I)x-(B)y or (B)y-(I)x

wherein:

the block (I) comprises at least one polymerized conjugated diene of formula (1);

the block (B) comprises at least one polymerized conjugated diene of formula (3);

x is the number of polymerized monomer units in block (I) and is at least 1, and y is the number of polymerized monomer units in block (B) and is at least 25.

25. The explosive emulsion composition of claim 24, wherein said block (I) and/or block (B) comprises the aryl-substituted olefin incorporated randomly or as block.