DISPERSIBLE FIBER BUNDLES AND SUSPENSIONS USING ENVIRONMENTALLY-FRIENDLY SOLVENTS

Abstract

Methods of preparing dispersible fiber bundles comprising contacting a rheology-modifying binder to at least two or more fibers to form a binder-fiber mixture, and imparting force to the binder-fiber mixture to compact the binder-fiber mixture into a fiber bundle.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 61/774,956 filed Mar. 8, 2013, incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

This invention relates to products, methods and processes related to dispersing fiber bundles in environmentally friendly solvents and related applications.

BACKGROUND OF THE INVENTION

Cut staple fibers are used in a variety of applications ranging from textiles, non-wovens, carpets, upholstery, filters, reinforcements for composites, or even hydraulic fracturing among many others. In all of these applications the dry staple fibers are difficult to handle due to the large volume of randomly oriented high aspect ratio cylinders, and their ability to get airborne often posing even an inhalation hazard (e.g. asbestos, glass fibers, and even polymeric fibers). These high volume fibers are usually costly to ship (in bulk) even if they are somewhat compacted in bales, but still need to be handled at the point of use. It also poses a problem for effectively metering the amount of fiber for any given industrial operation.

In many of the applications, to facilitate handling, the fibers are used as suspensions in aqueous, solvent or polymeric/resin media. In order to make the fiber suspensions, they are manually added from bags into mixing tanks with low process control. Effective mixing is required for proper dispersion, especially with glass fibers in organic media or hydrophobic fibers in water, where they have a natural tendency to cluster. Dispersing aids may be employed. There is also a need to add a rheology modifier to the suspension in order to be able to pump the suspension. In the absence of rheology control to transfer the shear stress to the fibers, the fibers simply tend to bridge with liquid drainage through a plug of fibers.

Thus, there is need to effectively manage the delivery and handling of short staple fibers especially when they need to be suspended in a liquid at the point of use.

SUMMARY OF INVENTION

Described herein are solutions related to managing volume issue for handling polymer fibers, and in particular, short staple fibers or cut staple fibers. In one embodiment, the polymer fibers are hydrophobic polymer fibers. In one embodiment, one solution includes compacting the staple fibers into bundles using an adhesive or binder.

In one aspect described herein are methods of preparing dispersible fiber bundles comprising contacting a rheology-modifying binder to at least two or more fibers to form a binder-fiber mixture, and imparting force to the binder-fiber mixture to compact the binder-fiber mixture into a fiber bundle.

In another aspect, described herein are methods of preparing dispersible fiber bundles comprising: contacting a rheology-modifying binder with at least two or more fibers to form a binder-fiber mixture; and imparting force to the binder-fiber mixture to substantially orient the at least two fibers in a first direction, thereby forming a fiber bundle. In one embodiment, the rheology-modifying binder is selected from at least one guar, at least one derivatized guar, at least one cellulose, at least one modified cellulose (e.g. hydroxyl ethyl cellulose, hydroxyl methyl cellulose), at least one acrylate, at least one viscoelastic surfactant, or any combination thereof. The fibers can be oriented in a substantially longitudinal direction. The method further includes severing the fiber bundle into two or more shorter length fiber bundles.

In another aspect, described herein are methods of preparing a dispersible fiber bundle slurry comprising: contacting a rheology-modifying binder to at least two or more fibers to form a binder-fiber mixture, imparting force to the binder-fiber mixture to substantially orient the at least two fibers in a first direction, thereby forming a fiber bundle; and contacting the fiber bundle with a solvent blend, the solvent blend comprising at least one of the following components:

a) dialkyl methylglutarate;

b) a first blend of: dialkyl methylglutarate, dialkyl ethylsuccinate and, optionally, dialkyl adipate;

c) a second blend of: dialkyl adipate, dialkyl glutarate and dialkyl succinate;

d) a dioxolane compound of formula I:

wherein R6 and R7, which may be identical or different, is individually a hydrogen, an alkyl group, an alkenyl group, or a phenyl group, wherein n is an integer of from 1 to 10; and

e) a compound or mixture of compounds having formula (II):

R₃OOC-A-CONR₄R₅  (II),

wherein R₃ is a group chosen from saturated or unsaturated, linear or branched, optionally cyclic, optionally aromatic hydrocarbon-based groups comprising an average number of carbon atoms ranging from 1 to 36; wherein R₄ and R₅, which are identical or different, are groups chosen from saturated or unsaturated, linear or branched, optionally cyclic, optionally aromatic, optionally substituted hydrocarbon-based groups comprising an average number of carbon atoms ranging from 1 to 36, it being possible for R4 and R5 to optionally together form a ring, that is optionally substituted; and wherein A is a linear or branched divalent alkyl group comprising an average number of carbon atoms ranging from 2 to 12.

In another aspect, described herein are fiber bundles comprising: at least two polymer fibers; and a rheology-modifying binder comprising at least one guar, at least one derivatized guar, at least one cellulose, at least one modified cellulose, at least one acrylate, at least one viscoelastic surfactant, or any combination thereof, wherein the fibers are treated with an effective amount of the binder to enhance the cohesion of the fiber bundle.

In another aspect, described herein are fiber bundle slurries comprising (1) a fiber bundle comprising: (a) at least two polymer fibers; and (b) a rheology-modifying binder comprising at least one guar, at least one derivatized guar, at least one cellulose, at least one modified cellulose, at least one acrylate, at least one viscoelastic surfactant, or any combination thereof, wherein the fibers are treated with an effective amount of the binder to enhance the cohesion of the fiber bundle; and (2) a solvent blend comprising at least one of the following components:

a) dialkyl methylglutarate;

b) a first blend of: dialkyl methylglutarate, dialkyl ethylsuccinate and, optionally, dialkyl adipate;

c) a second blend of: dialkyl adipate, dialkyl glutarate and dialkyl succinate;

d) a dioxolane compound of formula I:

wherein R6 and R7, which may be identical or different, is individually a hydrogen, an alkyl group, an alkenyl group, or a phenyl group, wherein n is an integer of from 1 to 10; and

e) a compound or mixture of compounds having formula (II):

R3OOC-A-CONR4R5  (II),

wherein R3 is a group chosen from saturated or unsaturated, linear or branched, optionally cyclic, optionally aromatic hydrocarbon-based groups comprising an average number of carbon atoms ranging from 1 to 36; wherein R4 and R5, which are identical or different, are groups chosen from saturated or unsaturated, linear or branched, optionally cyclic, optionally aromatic, optionally substituted hydrocarbon-based groups comprising an average number of carbon atoms ranging from 1 to 36, it being possible for R4 and R5 to optionally together form a ring, that is optionally substituted; and wherein A is a linear or branched divalent alkyl group comprising an average number of carbon atoms ranging from 2 to 12.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a photograph illustrating hydrophobic polymer fibers in different solvents, displaying dispersion behavior.

FIG. 2 is a photograph illustrating Compaction of hydrophobic polymer fibers into bundles using a guar solution followed by drying.

FIG. 3(a) is a photograph illustrating hydrophobic polymer-guar bundles hydrated and dispersed in water, side view.

FIG. 3(b) is a photograph illustrating hydrophobic polymer-guar bundles hydrated and dispersed in water, top view.

FIG. 4(a) is a photograph of compact hydrophobic polymer fiber bundles (10-12 mm spheres).

FIG. 4(b) is a photograph of compact hydrophobic polymer fiber bundles (7-9 mm spheres).

FIG. 4(c) is a photograph of compact hydrophobic polymer fiber (cylindrical shape).

FIG. 4(d) is a photograph of compact hydrophobic polymer fiber (cylindrical shape cut longitudinally into pieces).

FIG. 5(a) is a photograph of 10% w/w of 7-9 mm hydrophobic polymer spherical bundles (11.5% binder) suspended in dioxolane solvent-clay premix

FIG. 5 (b) is a photograph of 15% w/w of 6-8 mm cylinders (11.5% binder) suspended in a Rhodiasolv® Polarclean-clay premix.

FIG. 5 (c) is a photograph of hydrophobic polymer bundles suspended in the solvent-clay medium, illustrating flow properties.

DETAILED DESCRIPTION OF INVENTION

As used herein, the term “alkyl” means a saturated straight chain, branched chain, or cyclic hydrocarbon radical, including but not limited to, methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, t-butyl, pentyl, n-hexyl, and cyclohexyl.

As used herein, the term “aryl” means a monovalent unsaturated hydrocarbon radical containing one or more six-membered carbon rings in which the unsaturation may be represented by three conjugated double bonds, which may be substituted one or more of carbons of the ring with hydroxy, alkyl, alkenyl, halo, haloalkyl, or amino, including but not limited to, phenoxy, phenyl, methylphenyl, dimethylphenyl, trimethylphenyl, chlorophenyl, trichloromethylphenyl, aminophenyl, and tristyrylphenyl.

As used herein, the term “alkylene” means a divalent saturated straight or branched chain hydrocarbon radical, such as for example, methylene, dimethylene, trimethylene.

As used herein, the terminology “(Cr-Cs)” in reference to an organic group, wherein r and s are each integers, indicates that the group may contain from r carbon atoms to s carbon atoms per group.

As used herein, the terminology “surfactant” means a compound that when dissolved in an aqueous medium lowers the surface tension of the aqueous medium.

Described herein are water dispersible fiber bundles, methods of preparing the water dispersible fiber bundles and methods of dispersing the described fiber bundles in solution. Also described herein are processes to disperse or suspend polymer fibers, in particular, short staple fibers without the use special mixing equipment, which are very time-consuming and costly. In particular, described herein is the use of one or more water soluble rheology modifiers as a binder (or a component of the binder) to prepare staple fiber bundles, typically cut polymer fiber bundles. It has been surprisingly found that the treatment of short-cut polymer fibers with selected binders described herein leads to fiber bundles or pellets capable of being disperses more effectively into an aqueous matrix. It is understood that the term “bundles” incorporates any compact shape or form of fibers, including but not limited to bundles, pellets, clusters, bunches, clumps, mass, rolls, chunks, rods, arrangements, aggregations, assemblages or the like.

In one embodiment, the water soluble rheology modifier comprises a polysaccharide or modified polysaccharide. In one embodiment, the polysaccharide or modified polysaccharide comprises guar, derivatized guar, cellulose, modified cellulose, including but not limited to hydroxypropyl cellulose, hydroxymethyl cellulose, hydroxyl ethyl cellulose, acrylate, viscoelastic surfactant, or a combination thereof. In some embodiments the rheology-modifying binder is at least one guar, at least one guar derivative, or a combination thereof. In some embodiment, the rheology-modifying binder is at least one viscoelastic surfactant, or a combination of two or more viscoelastic surfactants.

The modified cellulose can include, for example, cationically modified cellulose derivatives containing hydroxy groups such as, cationically modified cellulose, cationically modified hydroxyl alkyl cellulose, such as hydroxyethyl cellulose and the like.

The fibers, or fiber bundles can be used in conjunction with other polymers and surfactants. In one embodiment, the fibers may be cellulose acetate, polyamide, PLA or PGA, PEEK, acrylic, polyester, glass, metal, inorganic, or any other non-water soluble fiber. In another embodiment, the fibers are selected from poly-3-hydroxybutyrate (PHB), polyhydroxyalkanoates (PHA), Polyamide 11 (PA 11) or the like. In another embodiment, the polymer fiber is non-water soluble or partially-water soluble. When these fiber bundles are hydrated the water soluble binder quickly dissolves, rapidly dispersing the fibers while building viscosity to shear and disperse the fibers more effectively into the aqueous matrix. This viscous suspension can then be pumped without the liquid drainage, bridging and clogging issues.

In one embodiment, the fibers have a staple length of from 1 to 50 mm. In another embodiment the fibers have a staple length of from 2 to 24 mm. In another embodiment the fibers have a staple length of from 3 to 20 mm. In a further embodiment the fibers have a staple length of from 6 to 12 mm. In another embodiment the fibers have a staple length of greater than 1 mm, or 2 mm, or 4 mm or 5 mm or 6 mm or 8 mm. In another embodiment the fibers have a staple length of greater than 4 mm. In another embodiment the fibers have a staple length of greater than 5 mm. In yet another embodiment the fibers have a staple length of greater than 6 mm. In another embodiment the fibers have a staple length of greater than 8 mm. In another embodiment the fibers have a staple length of greater than 10 mm. In another embodiment the fibers have a staple length of greater than 12 mm. In another embodiment the fibers have a staple length of greater than 14 mm. In another embodiment the fibers have a staple length of greater than 15 mm. In another embodiment the fibers have a staple length of greater than 20 mm. In some embodiments, staple length is the longitudinal length of a piece of cylindrical fiber that has been cut or severed perpendicular to its longitudinal axis.

In some embodiments, the fiber bundle or polymer fibers have an average staple length of at least 0.5 mm, at least 1 mm, at least 2 mm, at least 3 mm, at least 4 mm, at least 5 mm, or at least 6 mm or at least 10 mm, or at least 15 mm.

The rheology-modifying binder, in one embodiment, is selected from xanthans, such as xanthan gum, polyfructoses such as levan, and galactomannans such as guar gum, locust bean gum, tara gum, or a combination of any of the foregoing.

In one embodiment, the polysaccharide is a locust bean gum. Locust bean gum or carob bean gum is the refined endosperm of the seed of the carob tree, Ceratonia siliqua. The ratio of galactose to mannose for this type of gum is about 1:4. In one embodiment, the polysaccharide is a tara gum. Tara gum is derived from the refined seed gum of the tara tree. The ratio of galactose to mannose is about 1:3.

In one embodiment, the polysaccharide is a polyfructose. Levan is a polyfructose comprising 5-membered rings linked through β-2,6 bonds, with branching through β-2,1 bonds. Levan exhibits a glass transition temperature of 138° C. and is available in particulate form. At a molecular weight of 1-2 million, the diameter of the densely-packed spherulitic particles is about 85 nm.

In one embodiment, the polysaccharide is a xanthan. Xanthans of interest are xanthan gum and xanthan gel. Xanthan gum is a polysaccharide gum produced by Xathomonas campestris and contains D-glucose, D-mannose, D-glucuronic acid as the main hexose units, also contains pyruvate acid, and is partially acetylated.

In one embodiment, the polysaccharide of the present invention is derivatized or non-derivatized guar. Guar comes from guar gum, the mucilage found in the seed of the leguminous plant Cyamopsis tetragonolobus. The water soluble fraction (85%) is called “guaran,” which consists of linear chains of (1,4)-.β-D mannopyranosyl units-with α-D-galactopyranosyl units attached by (1,6) linkages. The ratio of D-galactose to D-mannose in guaran is about 1:2.

The guar seeds used to make guar gum are composed of a pair of tough, non-brittle endosperm sections, hereafter referred to as “guar splits,” between which is sandwiched the brittle embryo (germ). After dehulling, the seeds are split, the germ (43-47% of the seed) is removed by screening. The splits typically contain about 78-82% galactomannan polysaccharide and minor amounts of some proteinaceous material, inorganic salts, water-insoluble gum, and cell membranes, as well as some residual seedcoat and seed embryo.

In one embodiment, the rheology-modifying binder is selected from guar or derivatized guar.

In one embodiment, the guar is native guar, unwashed guar gum, washed guar gum, or a combination thereof. In one embodiment, the derivatized guar is cationic guar, carboxymethyl guar (CM guar), hydroxyethyl guar (HE guar), hydroxypropyl guar (HP guar), carboxymethylhydroxypropyl guar (CMHP guar), cationic guar, hydrophobically modified guar (HM guar), hydrophobically modified carboxymethyl guar (HMCM guar), hydrophobically modified hydroxyethyl guar (HMHE guar), hydrophobically modified hydroxypropyl guar (HMHP guar), cationic hydrophobically modified hydroxypropyl guar (cationic HMHP guar), hydrophobically modified carboxymethylhydroxypropyl guar (HMCMHP guar), hydrophobically modified cationic guar (HM cationic guar), guar hydroxypropyl trimonium chloride, hydroxypropyl guar hydroxypropyl trimonium chloride, or a combination of any of the foregoing.

In another embodiment, the rheology-modifying binder is a viscoelastic surfactant or a combination of viscoelastic surfactants

The viscoelastic surfactants include zwitterionic surfactants and/or amphoteric surfactants and cationic surfactants. A zwitterionic surfactant has a permanently positively charged moiety in the molecule regardless of pH and a negatively charged moiety at alkaline pH. A cationic surfactant has a positively charged moiety regardless of pH. An amphoteric surfactant has both a positively charged moiety and a negatively charged moiety over a certain pH range (e.g., typically slightly acidic), only a negatively charged moiety over a certain pH range (e.g., typically slightly alkaline) and only a positively charged moiety at a different pH range (e.g., typically moderately acidic).

In one embodiment, the cationic surfactant is selected from i) certain quaternary salts and ii) certain amines, iii) amine oxide, iv) and combinations thereof.

The quaternary salts have the structural formula:

wherein R₁ is a hydrophobic moiety of alkyl, alkylarylalkyl, alkoxyalkyl, alkylaminoalkyl or alkylamidoalkyl. R₁ has from about 18 to about 30 carbon atoms and may be branched or straight-chained and saturated or unsaturated. Representative long chain alkyl groups include octadecentyl (oleyl), octadecyl (stearyl), docosenoic (erucyl) and the derivatives of tallow, coco, soya and rapeseed oils. The preferred alkyl and alkenyl groups are alkyl and alkenyl groups having from about 18 to about 22 carbon atoms.

R₂, R₃, and R₅ are, independently, an aliphatic group having from 1 to about 30 carbon atoms or an aromatic group having from 7 to about 15 carbon atoms. The aliphatic group typically has from 1 to about 20 carbon atoms, more typically from 1 to about 10 carbon atoms, and most typically from 1 to about 6 carbon atoms. Representative aliphatic groups include alkyl, alkenyl, hydroxyalkyl, carboxyalkyl, and hydroxyalkyl-polyoxyalkylene. The aliphatic group can be branched or straight-chained and saturated or unsaturated. Preferred alkyl chains are methyl and ethyl. Preferred hydroxyalkyls are hydroxyethyl and hydroxypropyl. Preferred carboxyalkyls are acetate and propionate. Preferred hydroxyalkyl-polyoxyalkylenes are hydroxyethyl-polyoxyethylene and hydroxypropyl-polyoxypropylene. Examples of aromatic moieties include cyclic groups, aryl groups, and alkylaryl groups. A preferred alkylaryl is benzyl.

X is suitable anion, such as Cl⁻, Br⁻, and (CH₃)₂SO4⁻.

Representative quaternary salts of the above structure include methylpolyoxyethylene(12-18)octadecanammonium chloride, methylpolyoxyethylene(2-12)cocoalkylammonium chloride, and isotridecyloxypropyl polyoxyethylene (2-12) methyl ammonium chloride.

The amines have the following structural formula:

wherein R₁, R₂, and R₃ are as defined above.

Representative amines of the above structure include polyoxyethylene(2-15)cocoalkylamines, polyoxyethylene(12-18)tallowalkylamines, and polyoxyethylene(2-15)oleylamines.

Selected zwitterionic surfactants are represented by the following structural formula:

wherein R₁ is as described above. R₂ and R₃ are, independently, an aliphatic moiety having from 1 to about 30 carbon atoms or an aromatic moiety having from 7 to about 15 carbon atoms. The aliphatic moiety typically has from 1 to about 20 carbon atoms, more typically from 1 to about 10 carbon atoms, and most typically from 1 to about 6 carbon atoms. The aliphatic group can be branched or straight chained and saturated or unsaturated. Representative aliphatic groups include alkyl, alkenyl, hydroxyalkyl, carboxyalkyl, and hydroxyalkyl-polyoxyalkylene. Preferred alkyl chains are methyl and ethyl. Preferred hydroxyalkyls are hydroxyethyl and hydroxypropyl. Preferred carboxyalkyls are acetate and propionate. Preferred hydroxyalkyl-polyoxyalkylenes are hydroxyethyl-polyoxyethylene or hydroxypropyl-polyoxypropylene). R₄ is a hydrocarbyl radical (e.g. alkylene) with chain length 1 to 4 carbon atoms. Preferred are methylene or ethylene groups. Examples of aromatic moieties include cyclic groups, aryl groups, and alkylaryl groups. A preferred arylalkyl is benzyl.

Specific examples of selected zwitterionic surfactants include the following structures:

wherein R₁ is as described above.

Other representative zwitterionic surfactants include dihydroxyethyl tallow glycinate, oleamidopropyl betaine, and erucyl amidopropyl betaine.

Selected amphoteric surfactants useful in the viscoelastic surfactant fluid of the present invention are represented by the following structural formula:

wherein R₁, R₂, and R₄ are as described above.

Specific examples of amphoteric surfactants include those of the following structural formulas:

wherein R₁ is as described above. X⁺ is an inorganic cation such as Na⁺, K⁺, NH₄⁺ associated with a carboxylate group or hydrogen atom in an acidic medium.

The selected zwitterionic and amphoteric surfactants are functionally interchangeable and may be used separately or alone (alternatively) or in combination with each other.

The fiber bundles can include (in either the product, process of making or during dispersion into solution), various other additives. Non-limiting examples include stabilizers, thickeners, corrosion inhibitors, mineral oils, enzymes, ion exchangers, chelating agents, dispersing agents and the like. In one particular embodiment, fiber bundles can include (in either the product, process of making or during dispersion into solution), polyacrylates, polyDADMAC [poly(diallyl dimethyl ammonium chloride] and combinations thereof), and clay (Bentonite and attapulgite).

A guar solution was utilized to bind hydrophobic polymer fibers together in spherical and cylindrical bundles, which was observed to disperse rapidly when mixed in water. Guar is especially effective in low concentrations as it hydrates and builds viscosity rapidly. This couples the fibers and rheology modifiers into a packaged solution while addressing most issues in handling of staple fibers. In such an embodiment, it is not necessary to separately add a viscosity builder for any suitable industrial application, including hydraulic fracturing application. (In some embodiments, it may be useful, however, to add a viscosity builder or other additive.) It dramatically reduces the volume occupied by the fiber, handling issues, and transportation cost. These bundles may be metered and conveyed pneumatically.

As described above, there are also existing problems associated in the transportation and handling of bulk dry staple fibers, and in particular in the end use handling in suitable industrial applications, e.g., textile industry. In many instances, it is preferable to load an ingredient to a mixture into a loading tank and pump it to a mixing tank. However, this is not feasible sometimes, when ingredients are shipped in dry bulk form, and an operator would likely have to manually add it by hand, which introduces variables such as human error. In one embodiment, described herein are compositions and products that include the fiber bundles as described herein suspended in a solvent to form a slurry. The fiber bundles, in this slurry or liquid form, can easily be pumped and metered into tanks such as loading tanks, as well as to and from other tanks. The solvent can be, in some embodiments, an environmentally-friendly solvent that is at least partially biodegradable or has a favorable eco-toxicity profile (as compared with commonly used solvents in the industry). Typically, the solvent or solvent mixture is chosen such that neither the water soluble binder nor the polymeric staple fibers are soluble in the solvent to an appreciable degree.

In one embodiment, the solvent or solvent blend is chosen from at least one of the following components, below:

a) dialkyl methylglutarate;

b) a first blend of: dialkyl methylglutarate, dialkyl ethylsuccinate and, optionally, dialkyl adipate;

c) a second blend of: dialkyl adipate, dialkyl glutarate and dialkyl succinate;

d) a dioxolane compound of formula I:

wherein R6 and R7, which may be identical or different, is individually a hydrogen, an alkyl group, an alkenyl group, a phenyl group, wherein n is an integer of from 1 to 10;

e) a compound or mixture of compounds having formula (II):

R₃OOC-A-CONR₄R₅  (II),

wherein R₃ is a group chosen from saturated or unsaturated, linear or branched, optionally cyclic, optionally aromatic hydrocarbon-based groups comprising an average number of carbon atoms ranging from 1 to 36; wherein R₄ and R₅, which are identical or different, are groups chosen from saturated or unsaturated, linear or branched, optionally cyclic, optionally aromatic, optionally substituted hydrocarbon-based groups comprising an average number of carbon atoms ranging from 1 to 36, it being possible for R₄ and R₅ to optionally together form a ring, that is optionally substituted and/or that optionally comprises a heteroatom; and wherein A is a linear or branched divalent alkyl group comprising an average number of carbon atoms ranging from 2 to 12, typically from 2 to 4;

In one embodiment, the solvent blend is selected for a blend of dibasic esters. Dibasic esters of the present invention may be derived from one or more by-products in the production of polyamide, for example, polyamide 6,6. In one embodiment, the cleaning composition comprises a blend of linear or branched, cyclic or noncyclic, C1-C20 alkyl, aryl, alkylaryl or arylalkyl esters of adipic diacids, glutaric diacids, and succinic diacids. In another embodiment, the cleaning composition comprises a blend of linear or branched, cyclic or noncyclic, C1-C20 alkyl, aryl, alkylaryl or arylalkyl esters of adipic diacids, methylglutaric diacids, and ethylsuccinic diacids

Generally, polyamide is a copolymer prepared by a condensation reaction formed by reacting a diamine and a dicarboxylic acid. Specifically, polyamide 6,6 is a copolymer prepared by a condensation reaction formed by reacting a diamine, typically hexamethylenediamine, with a dicarboxylic acid, typically adipic acid.

In one embodiment, the blend of dibasic esters can be derived from one or more by-products in the reaction, synthesis and/or production of adipic acid utilized in the production of polyamide, the cleaning composition comprising a blend of dialkyl esters of adipic diacids, glutaric diacids, and succinic diacids (herein referred to sometimes as “AGS” or the “AGS blend”).

In one embodiment, the blend of esters is derived from by-products in the reaction, synthesis and/or production of hexamethylenediamine utilized in the production of polyamide, typically polyamide 6,6. The cleaning composition comprises a blend of dialkyl esters of adipic diacids, methylglutaric diacids, and ethylsuccinic diacids (herein referred to sometimes as “MGA”, “MGN”, “MGN blend” or “MGA blend”).

In certain embodiments, the dibasic ester blend comprises:

a diester of formula I:

a diester of formula II:

and

a diester of formula III:

R1 and/or R2 can individually comprise a hydrocarbon having from about 1 to about 8 carbon atoms, typically, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, n-butyl, isoamyl, hexyl, heptyl or octyl. In such embodiments, the blend typically comprises (by weight of the blend) (i) about 15% to about 35% of the diester of formula I, (ii) about 55% to about 70% of the diester of formula II, and (iii) about 7% to about 20% of the diester of formula III, and more typically, (i) about 20% to about 28% of the diester of formula I, (ii) about 59% to about 67% of the diester of formula II, and (iii) about 9% to about 17% of the diester of formula III. The blend is generally characterized by a flash point of 98° C., a vapor pressure at 20° C. of less than about 10 Pa, and a distillation temperature range of about 200-300° C. Mention may also be made of Rhodiasolv® RPDE (Rhodia Inc., Cranbury, N.J.), Rhodiasolv® DIB (Rhodia Inc., Cranbury, N.J.) and Rhodiasolv® DEE (Rhodia Inc., Cranbury, N.J.).

In certain other embodiments, the dibasic ester blend comprises:

a diester of the formula IV:

a diester of the formula V:

and, optionally,

a diester of the formula VI:

R1 and/or R2 can individually comprise a hydrocarbon having from about 1 to about 8 carbon atoms, typically, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, n-butyl, isoamyl, hexyl, heptyl, or octyl. In such embodiments, the blend typically comprises (by weight of the blend) (i) from about 5% to about 30% of the diester of formula IV, (ii) from about 70% to about 95% of the diester of formula V, and (iii) from about 0% to about 10% of the diester of formula VI. More typically, the blend typically comprises (by weight of the blend): (i) from about 6% to about 12% of the diester of formula IV, (ii) from about 86% to about 92% of the diester of formula V, and (iii) from about 0.5% to about 4% of the diester of formula VI.

Most typically, the blend comprises (by weight of the blend): (i) about 9% of the diester of formula IV, (ii) about 89% of the diester of formula V, and (iii) about 1% of the diester of formula VI. The blend is generally characterized by a flash point of 98° C., a vapor pressure at 20° C. of less than about 10 Pa, and a distillation temperature range of about 200-275° C. Mention may be made of Rhodiasolv® IRIS (Rhodia Inc., Cranbury, N.J.) and Rhodiasolv® DEE/M (Rhodia Inc., Cranbury, N.J.)

In another embodiment, the solvent blend can include other solvents, including but not limited to aliphatic or acyclic hydrocarbons solvents, halogenated solvents, aromatic hydrocarbon solvents, cyclic terpenes, unsaturated hydrocarbon solvents, halocarbon solvents, polyols, alcohols including short chain alcohols, ketones or mixtures thereof.

The dioxane compound utilized as the alternative solvent or in the alternative solvent blend as described herein includes those of formula (I), below:

in which: R6 and R7, which are identical or different, represent hydrogen or a C1-C14 group or radical. In one embodiment, R6 and R7 are individually selected from an alkyl group, alkenyl group or phenyl radical. In some embodiments, “n” is an integer of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12. Typically, “n” is an integer from about 1 to 4. More typically, “n” is 1 or 2.

In one particular embodiment, R6 and R7 are radicals individually selected from methyl, ethyl, n-propyl, isopropyl or isobutyl radical.

In one embodiment the dioxolane compound is of formula (I) is 2,2-dimethyl-1,3-dioxolane-4-methanol. In another embodiment, the dioxolane compound of formula (I) is 2,2-diisobutyl-1,3-dioxolane-4-methanol (also known by the acronym IIPG, for the synonym 1-isobutyl-isopropylidene glycerol).

Hydrophobic polymer bundles were suspended in a green ecofriendly solvent such as Rhodiasolv IRIS, RPDE, Augeo, DIB etc. This slurry of hydrophobic polymer bundles converts the delivery system into a liquid form that can easily be pumped and metered into tanks. This also removes the hazard associated with the handling of fibers while improving transportation/storage profile.

EXPERIMENTS

Example 1

Solvent Screening

Hydrophobic polymer fibers of <10 mm length and <50 μm diameter with a high aspect ratio (L/D=150) were used. 1 g of the fibers was placed in 20 mL glass vials and occupied a uncompressed volume of 10-15 mL. 10 g of a range of solvents Rhodiasolv IRIS (branched dibasic esters of glutaric and adipic acid), RPDE (linear dibasic esters of glutaric, succinic, and adipic acid), Augeo (glyceryl ketal), Polarclean (ether amide), ADMA (alkyl dimethyl amide), DIB (Diisobutyl ester), and DEE (linear diethyl ester mix) were added as shown in middle row of FIG. 1 (10%). The solvents barely cover the fiber mass which behaves as a wet wooly mass that is not pumpable. Further addition of solvent to the vials (bottom row of FIG. 1) dilutes the hydrophobic polymer concentration to merely 5% and the fibers occupy the entire volume of the vial. The fiber suspension is still a plug at this concentration that would only be pumped with difficulty with solvent drainage through the mass. One can still visualize clusters of fibers in white aggregates suggesting poor dispersion of individual fibers. This example demonstrates that staple fibers as supplied cannot be suspended at high concentrations in a liquid medium.

Example 2

Hydrophobic Polymer Fiber Bundles

Hydrophobic polymer staple fibers were compacted with native guar (Higum 1122) as binder. 15 g of a viscous Higum 1122 solution at a concentration of 1% w/w was added to 5 g of hydrophobic polymer staple fibers. The two were mixed together into a paste. The paste was then rolled into spherical bundles (10-12 mm) in diameter. These bundles were then dried in a convection oven at 65° C. overnight. Referring to FIG. 2, a significant reduction in volume occupied was achieved while improving the handling characteristics. These pellets can be pneumatically conveyed.

These pellets were then added to water with stirring such that the concentration of the hydrophobic polymer fibers in the final suspension was ˜1%. Simple mixing without the need for specialized equipment allows easy hydration of the bundles. Hydrophobic polymer fibers were dispersed through the bulk of the suspension as shown in FIGS. 3(a) and 3(b). The suspension was observed to be stable over several weeks.

Example 3

Increasing Hydrophobic Polymer Fiber Bundle Density

The density of the fiber bundles and the size can be further reduced and optimized as shown in FIGS. 4(a)-4(d). FIG. 4(a) shows a paste polymer with 1% binder solution, dryed at 65° C. overnight. FIG. 4(b) shows a dry polymer fiber and binder polymer (10%) mixed with a paste with 1% binder solution, dryed at 65° C. overnight. FIG. 4(c) shows a dry polymer fiber and binder polymer (10%) mixed with a paste with 1% binder solution, rolled into cylinders, dryed at 65° C. overnight. FIG. 4(d) shows a dry polymer fiber and binder polymer (10%) mixed with a paste with 1% binder solution, rolled into cylinders, dryed at 65° C. overnight, which are cut into pieces having staple lengths of about 6-8 mm. Increasing the guar binder concentration cannot be easily achieved due to the high viscosity of the 1% guar solution. The hydrophobic polymer fibers bundles as described in Example 2 are shown in FIG. 4(a). In order to reduce the bundles size dry guar powder and hydrophobic polymer fibers were mixed and then 1% solution of guar was added to yield a more viscous paste and adhesive binder content. The hydrophobic polymer fibers could now be rolled into a more compact sphere, as illustrated in FIG. 4(b).

In order to further increase the density (packing fraction) the viscous paste so prepared was rolled into cylinders (FIG. 4(c); approx. 4 mm diameter) and dried in a convection oven. This aligns the fibers and allows for greater degree of packing and density. These were then further cut into 6-8 mm cylinders (i.e., staple length). This would allow for more efficient packing into a slurry.

Example 4

Hydrophobic Polymer Bundles in Solvent Suspensions

hydrophobic polymer bundles were then suspended in solvents screened in Example 1. A pregel of clay in solvent was prepared to provide viscosity and suspending properties to the solvent. Several clays were screened and Benathix® from Elementis was found to be the most effective for the solvents as described herein. The clay concentration was 4% (as shown in FIG. 5(a)), and 2% (as shown in FIGS. 5(b), 5(c)). The higher density cylinders as shown in FIG. 5(b) can be packed at higher concentrations w/w into the solvent-clay medium. This suspension can flow as shown in FIG. 5(c) in contrast with the fibers alone as shown in FIG. 1. This suspension can be hydrated in water.

It should be apparent that embodiments and equivalents other than those expressly discussed above come within the spirit and scope of the present invention. Thus, the present invention is not limited by the above description but is defined by the appended claims.

Claims

1. A method of preparing dispersible fiber bundles comprising contacting a rheology-modifying binder with at least two or more fibers to form a binder-fiber mixture, and imparting force to the binder-fiber mixture to compact the binder-fiber mixture into a fiber bundle, wherein the rheology-modifying binder is selected from at least one guar, at least one derivatized guar, at least one modified cellulose, at least one acrylate, at least one viscoelastic surfactant, or any combination thereof.

2. The method of claim 1 wherein the rheology-modifying binder is at selected from at least one guar,

3. A method of preparing dispersible fiber bundles comprising:

contacting a rheology-modifying binder with at least two or more fibers to form a binder-fiber mixture;

imparting force to the binder-fiber mixture to substantially orient the at least two fibers in a first direction, thereby forming a fiber bundle; and

severing the fiber bundle into two or more shorter length fiber bundles.

4. The method of claim 3 wherein the rheology-modifying binder is selected from at least one guar, at least one derivatized guar, at least one modified cellulose, at least one acrylate, at least one viscoelastic surfactant, or any combination thereof.

5. The method of claim 3 wherein the at least two fibers are oriented in a substantially longitudinal direction.

6. The method of claim 3 wherein the at least two fibers are selected from cellulose acetate, polyamide, PLA, PGA, PEEK, acrylic, polyester, glass, metal, inorganic, poly-3-hydroxybutyrate (PHB), polyhydroxyalkanoates (PHA), Polyamide 11 (PA 11) or any combination thereof.

7. A method of preparing a dispersible fiber bundle slurry comprising: wherein R6 and R7, which may be identical or different, is individually a hydrogen, an alkyl group, an alkenyl group, or a phenyl group, wherein n is an integer of from 1 to 10; and wherein R3 is a group chosen from saturated or unsaturated, linear or branched, optionally cyclic, optionally aromatic hydrocarbon-based groups comprising an average number of carbon atoms ranging from 1 to 36; wherein R4 and R5, which are identical or different, are groups chosen from saturated or unsaturated, linear or branched, optionally cyclic, optionally aromatic, optionally substituted hydrocarbon-based groups comprising an average number of carbon atoms ranging from 1 to 36, it being possible for R4 and R5 to optionally together form a ring, that is optionally substituted; and wherein A is a linear or branched divalent alkyl group comprising an average number of carbon atoms ranging from 2 to 12.

contacting a rheology-modifying binder to at least two or more fibers to form a binder-fiber mixture,

imparting force to the binder-fiber mixture to substantially orient the at least two fibers in a first direction, thereby forming a fiber bundle; and

contacting the fiber bundle with a solvent blend, the solvent blend comprising at least one of the following components: a) dialkyl methylglutarate; b) a first blend of: dialkyl methylglutarate, dialkyl ethylsuccinate and, optionally, dialkyl adipate; c) a second blend of: dialkyl adipate, dialkyl glutarate and dialkyl succinate; d) a dioxolane compound of formula I:

e) a compound or mixture of compounds having formula (II): R3OOC-A-CONR4R5  (II),

8. The method of claim 7 wherein the at least two fibers are oriented in a substantially longitudinal direction.

9. The method of claim 7 further comprising:

severing the fiber bundle into two or more shorter length fiber bundles; or

compacting the fiber bundle.

10. The method of claim 7 wherein the at least two fibers are selected from cellulose acetate, polyamide, PLA, PGA, PEEK, acrylic, polyester, glass, metal, inorganic, poly-3-hydroxybutyrate (PHB), polyhydroxyalkanoates (PHA), Polyamide 11 (PA 11) or any combination thereof.

11. A fiber bundle comprising:

at least two polymer fibers; and

a rheology-modifying binder comprising at least, one guar, at least one derivatized guar, at least one modified cellulose, at least one cellulose, at least one acrylate, at least one viscoelastic surfactant, or any combination thereof, wherein the fibers are treated with an effective amount of the binder to enhance the cohesion of the fiber bundle.

12. The fiber bundle of claim 11 wherein the at least two polymer fibers is selected from cellulose acetate, polyamide, PLA, PGA, PEEK, acrylic, polyester, glass, metal, inorganic, poly-3-hydroxybutyrate (PHB), polyhydroxyalkanoates (PHA), Polyamide 11 (PA 11) or any combination thereof.

13. A fiber bundle slurry comprising: wherein R6 and R7, which may be identical or different, is individually a hydrogen, an alkyl group, an alkenyl group, or a phenyl group, wherein n is an integer of from 1 to 10; and wherein R3 is a group chosen from saturated or unsaturated, linear or branched, optionally cyclic, optionally aromatic hydrocarbon-based groups comprising an average number of carbon atoms ranging from 1 to 36; wherein R4 and R5, which are identical or different, are groups chosen from saturated or unsaturated, linear or branched, optionally cyclic, optionally aromatic, optionally substituted hydrocarbon-based groups comprising an average number of carbon atoms ranging from 1 to 36, it being possible for R4 and R5 to optionally together form a ring, that is optionally substituted; and wherein A is a linear or branched divalent alkyl group comprising an average number of carbon atoms ranging from 2 to 12.

a fiber bundle comprising: a) at least two polymer fibers; and b) a rheology-modifying binder comprising at least one guar, at least one derivatized guar, at least one modified cellulose, at least one cellulose, at least one acrylate, at least one viscoelastic surfactant, or any combination thereof, wherein the fibers are treated with an effective amount of the binder to enhance the cohesion of the fiber bundle; a solvent blend comprising at least one of the following components:

a) dialkyl methylglutarate;

b) a first blend of: dialkyl methylglutarate, dialkyl ethylsuccinate and, optionally, dialkyl adipate;

c) a second blend of: dialkyl adipate, dialkyl glutarate and dialkyl succinate;

d) a dioxolane compound of formula I:

e) a compound or mixture of compounds having formula (II): R3OOC-A-CONR4R5  (II),

14. The fiber bundle slurry of claim 13 wherein the at least two polymer fibers is selected from cellulose acetate, polyamide, PLA, PGA, PEEK, acrylic, polyester, glass, metal, inorganic, poly-3-hydroxybutyrate (PHB), polyhydroxyalkanoates (PHA), Polyamide 11 (PA 11) or any combination thereof.

15. The fiber bundle of claim 11 wherein the polymer fibers have an average staple length of at least 4 mm.

16. The fiber bundle of claim 11 wherein the polymer fibers have an average staple length of at least 10 mm.

17. The fiber bundle of claim 11 wherein the polymer fibers have an average staple length of at least 15 mm.

18. The fiber bundle slurry of claim 13 wherein the polymer fibers have an average staple length of at least 4 mm.

19. The fiber bundle slurry of claim 13 wherein the polymer fibers have an average staple length of at least 10 mm.

20. The fiber bundle slurry of claim 13 wherein the polymer fibers have an average staple length of at least 15 mm.