Powders From Wax-Based Colloidal Dispersions and Their Process of Making
This invention relates to colloidally-protected, wax-based microstructures and dispersions thereof. More specifically, this invention relates to powders prepared from colloidally-protected, wax-based microstructure dispersions and process of making such powders. This invention also relates to a various end-use compositions comprising such powders from wax-based colloidal dispersions.
The present application is a continuation of U.S. application Ser. No. 14/863,648, filed Sep. 24, 2015, which claims benefit of U.S. Provisional Patent Application No. 62/056,087, filed Sep. 26, 2014, which is hereby incorporated by reference in its entirety.
TECHNICAL FIELDThis invention relates to wax-based colloidal dispersions. More specifically, this invention relates to powders prepared from wax based colloidal dispersion and process of making such powders. This invention also relates to various end-use compositions comprising such powders from wax-based colloidal dispersions.
BACKGROUNDNatural and synthetic waxes are used in many industries. Generally, waxes are organic compounds that characteristically consist of long alkyl chains. Natural waxes generally include plant-based, animal-based, or fossil-based waxes. Plant waxes include mixtures of unesterified hydrocarbons, mixtures of substituted long-chain aliphatic hydrocarbons, containing alkanes, alkyl esters, fatty acids, primary and secondary alcohols, diols, ketones, aldehydes. Generally, animal based waxes are derived from a variety of carboxylic acids and fatty alcohols. Fossil-based waxes include petroleum-based and mineral-based waxes. For example, paraffin waxes are hydrocarbons, mixtures of alkanes usually in a homologous series of chain lengths. Paraffin waxes are largely saturated n-alkanes. Similarly, montan wax is a fossilized wax extracted from coal and lignite, with high concentration of saturated fatty acids/esters and alcohols. Synthetic waxes are chemically prepared and include, for example, polypropylene, polyethylene, and polytetrafluoroethylene-based waxy materials.
Emulsions are formed from such natural and synthetic waxes and their blends. Such wax emulsions are used for example, in products within the construction industry, notably in gypsum wallboard for waterproofing and in oriented strand boards. Wax emulsions have been used in composite wallboard (e.g., gypsum wallboard) for many years.
While wax emulsions are used in building construction and other areas, adding wax emulsion liquids to a variety of products may become difficult due to inconsistencies in viscosity, mixing, or simply because water is not desirable or compatible in that particular application. Handling may also be an issue because the wax emulsions is in a liquid or paste form. Accordingly, there is a need in the art for compositions that maintain some, if not all, of the characteristics of the wax emulsion, such as water repellency, but at the same time can be delivered in a different physical structure. This invention relates to novel materials made from colloidal dispersions such as the wax emulsions and methods for making such novel materials. The novel materials possess a solid physical structure that retains some or all of the critical characteristics of the colloidal dispersions.
SUMMARYThe following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects of the present invention. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects of the present invention. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description of the invention that is presented later.
Disclosed herein is a process for preparing a powder from a wax-based colloidal dispersion, comprising:
providing at least one wax-based colloidal dispersion;
subjecting said wax-based colloidal dispersion to at least one powder-making process; and
optionally subjecting the resulting powder from step (B) to a size reduction process.
wherein said wax-based colloidal dispersion emulsion is optionally subjected to additional drying before, during, or after said at least one powder-making process.
In one embodiment, this invention also relates to the above process, wherein said at least powder-making process is selected from the group consisting of freeze drying; lyophilization, vacuum drying; air drying; spray drying; atomization; evaporation; tray drying; flash drying; drum drying; fluid-bed drying; oven drying; belt drying; microwave drying; solar drying; linear combinations thereof and parallel combinations thereof.
This invention also relates to the process described above wherein said wax-based colloidal dispersion is a wax-based emulsion.
In another embodiment, this invention also relates to the process described above, wherein the wax-based emulsion comprises at least one wax selected from the group consisting of animal-based wax, plant-based wax, mineral wax, synthetic wax, or a wax containing organic acids and/or esters, or a emulsifier containing a mixture of organic acids and/or esters, or combinations thereof.
This invention also relates to the process described above, wherein:
said animal-based wax is selected from the group consisting of beeswax, insect wax, spermaceti wax, lanolin, lanocerin, shellac, ozokerite, and combinations thereof;
said plant-based wax is selected from carnauba wax, candelilla wax, ouricury wax, jojoba plant wax, bayberry wax, Japan wax, sunflower wax, tall oil, tallow wax, rice wax, tallows, and combinations thereof;
said mineral wax is selected from montan wax, paraffin wax, microcrystalline wax, intermediate wax, and combinations thereof; and
said synthetic wax is selected from polypropylene, polyethylene, polytetrafluoroethylene, fatty acid amines based wax, Fischer Tropsch wax, polyamide wax, and combinations thereof.
In another embodiment, this invention relates to the powder prepared by the process described above. In another embodiment, the powder comprises particles in the average particle size range of from about 1 to about 1000 micron. Further, for this powder, the average particle size of at least about 10% by weight of said powder is less than a number selected from the range of from about 1 and 1000 microns; or the average particle size of at least about 50% by weight of said powder is less than a number selected from the range of from about 1 and 1000 microns; or the average particle size of at least about 90% by weight of said powder is less than a number selected from the range of from about 1 and 1000 microns. This invention further relates to a blended powder comprising at least two powders prepared by the process described above, wherein said at least two powders are chemically different from each other in their said wax-based colloidal dispersion composition.
This invention also relates to a blended powder comprising at least two powders prepared as recited in above, wherein said at least two powders are chemically similar to each other in their said wax-based colloidal dispersion composition, but differ in their particle size or method of making said powders.
This invention further relates to materials used for a variety of applications, for example, in the construction industry, or otherwise, wherein said material comprises the powder prepared as recited above, wherein said powder is in the amount of from about 1% to 50% by weight of said material.
This invention also relates to the powder prepared by the process as recited above, wherein said wax-based colloidal dispersion is stabilized by the steric hindrance, electrostatic repulsion, or both. In yet another embodiment, this invention relates to the powder as recited previously, wherein particles of said powder comprise a core comprising a wax, said core being colloidally protected by an outer brush comprising polymeric moieties.
In one embodiment, the wax-based colloidal dispersion from which the powder is made comprises water; polyvinyl alcohol; paraffin wax; microcrystalline wax and montan wax. In another embodiment of the invention, said wax is selected from polyethylene glycol, methoxypolyethylene glycol, and combination thereof.
The disclosed aspects will hereinafter be described in conjunction with the appended drawings, provided to illustrate and not to limit the disclosed aspects, wherein like designations denote the elements.
The terms “approximately”, “about”, and “substantially” as used herein represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of the stated amount.
Embodiments of the present disclosure provide a powder that is prepared from a wax based colloidal dispersion. The present invention also relates to methods for preparing powders from such wax based colloidal dispersions.
DefinitionsFor the purposes of this invention, a “colloidal dispersion” is a dispersion of a discontinuous phase in a continuous phase, comprising colloidally-protected wax-based microstructures.
By “wax-based colloidal dispersion” is meant an aqueous or non-aqueous colloidally occurring dispersion or mixture that is in liquid or paste like form comprising wax materials. A wax-based colloidal dispersion may also include the class of materials that are a suspension or other colloidal mixture comprising wax. It may also include wax-based emulsions. Wax-based colloidal dispersion in the present context is alternatively addressed as dispersion comprising colloidally-protected wax-based microstructure (CPWB microstructure). By “colloidally-protected wax-based microstructure” (CPWB microstructure) is meant a colloidal dispersion or emulsion, wherein the microstructure is colloidally protected with a wax or a lower fraction hydrocarbon core. The microstructure can exist in a dispersion or emulsion form.
By “wax” is meant any naturally occurring or synthetically occurring wax. It also includes blends or mixtures of one or more naturally occurring and/or synthetically occurring waxes. Those of animal origin typically consist of wax esters derived from a variety of carboxylic acids and fatty alcohols. The composition depends not only on species, but also on geographic location of the organism. Because they are mixtures, naturally produced waxes are softer and melt at lower temperatures than the pure components. Waxes are further discussed infra.
By “emulsion” or “wax-based emulsion” is meant an aqueous colloidally occurring dispersion or mixture in a liquid or paste-like form comprising wax materials, which has both the discontinuous and the continuous phases, preferably as liquid. For example, an aqueous wax system can either be a general colloid, or it can be an emulsion (which is a type of colloid), depending on the melt temperature of the emulsified wax versus the use temperature. In the disclosure below, the term “emulsion” is used. It should be noted, however, that a colloidal dispersion is also within the scope of the present invention.
Colloidally-Protected Wax-Based MicrostructuresThis invention relates to powder materials that comprise CPWB microstructures. CPWB microstructures have a wax core and film or casing of polymeric moieties which are adhered to the core via secondary forces such as Van Der Waals forces as opposed to a mechanical shell over a core in a classical core-shell structure. CPWB microstructures are described in detail below. In the aqueous emulsion of the powder form of emulsion comprising the CPWB microstructures, the core may be fully or partially encapsulated, in that the colloidal shell is not a physical shell like that of a typical core-shell structure.
CPWB Microstructure ShellIn a preferred embodiment, the polymers selected for the shell of the CPWB microstructures for low-dust joint compound applications are one or more of the following: Polyvinyl alcohol and copolymers, cellulose ethers, polyethylene oxide, polyethyleneimines, polyvinylpyrrolidone, and copolymers, polyethylene glycol, polyacrylamides and poly (N-isopropylamides, pullulan, sodium alginate, gelatin, and starches. Polyvinyl alcohol and copolymers are preferred.
CPWB Microstructure CoreThe core of the colloidally-protected wax-based microstructures can be a paraffin wax that is a linear alkane with a general formula of CnH2n+2, wherein n varies from 13 to 80. The paraffin wax defined by n=13 is called tridecane and the one with n=80 is octacontane. The melting point of C13 wax is −5.4° C. Similarly, the melting point of the C60 wax is 100° C. Similarly, the melting point of higher waxes (between C60 and C80) is higher than 100° C. but lower than the melting point of the colloidally-protective polymeric shell.
Some embodiments of the present invention envision wax that comprises branched structures, such as microcrystalline wax, as well as a blend or mixture of linear and branched structures of the wax. This invention also embodies mixtures or blends of waxes with two or more carbon numbers that may either be linear, branched, or blends of linear and branched structures. For example, a wax could be a mixture of C15 linear and C20 linear hydrocarbon alkane wax. In another example, the wax could be a mixture of C16 linear and C16 branched hydrocarbon alkane wax. In yet another example, the wax could be a mixture of C15 linear, C16 linear, and C20 branched. In yet another example, the wax could be a mixture of C18 linear, C18 branched.
Waxes usable as core in the CPWB microstructure-based emulsion of the present invention are described below.
WaxesFor the purposes of the present invention, waxes include naturally occurring waxes and synthetic waxes. Naturally occurring waxes include plant based waxes, animal waxes, and mineral waxes. Synthetic waxes are made by physical or chemical processes. Examples of plant based waxes include mixtures of unesterified hydrocarbons, which may predominate over esters. The epicuticular waxes of plants are mixtures of substituted long-chain aliphatic hydrocarbons, containing alkanes, alkyl esters, sterol esters, fatty acids, primary and secondary alcohols, diols, ketones, aldehydes, aliphatic aldehydes, primary and secondary alcohols, β-diketones, triacylglycerols, and many more. The nature of the other lipid constituents can vary greatly with the source of the waxy material, but they include hydrocarbons. Specific examples of plant wax include Carnauba wax, which is a hard wax obtained from the Brazilian palm Copernicia prunifera, which contains the ester myricyl cerotate. Other plant based waxes include candelilla wax, ouricury wax, jojoba plant wax, bayberry wax, Japan wax, sunflower wax, tall oil, tallow wax, rice wax, and tallows.
Animal wax includes beeswax as well as waxes secreted by other insects. A major component of the beeswax used in constructing honeycombs is the ester myricyl palmitate which is an ester of triacontanol and palmitic acid. Spermaceti occurs in large amounts in the head oil of the sperm whale. One of its main constituents is cetyl palmitate, another ester of a fatty acid and a fatty alcohol. Lanolin is a wax obtained from wool, consisting of esters of sterols. Other animal wax examples include lanocerin, shellac, and ozokerite.
Examples of mineral waxes include montan wax, paraffin wax, microcrystalline wax and intermediate wax. Although many natural waxes contain esters, paraffin waxes are hydrocarbons, mixtures of alkanes usually in a homologous series of chain lengths. Paraffin waxes are mixtures of saturated n- and iso-alkanes, naphthenes, and alkyl- and naphthene-substituted aromatic compounds. The degree of branching has an important influence on the properties. Montan wax is a fossilized wax extracted from coal and lignite. It is very hard, reflecting the high concentration of saturated fatty acids/esters and alcohols. Montan wax includes chemical components formed of long chain alkyl acids and alkyl esters having chain lengths of about 24 to 30 carbons. In addition, natural montan includes resin acids, polyterpenes and some alcohol, ketone and other hydrocarbons such that it is not a “pure” wax. The saponification number of montan, which is a saponifiable wax, is about 92 and its melting point is about 80° C. In addition to montan wax, other naturally derived waxes are known for use in various industries and include petroleum waxes derived from crude oil after processing, which include macrocrystalline wax, microcrystalline wax, petrolatum and paraffin wax. Paraffin wax is also a natural wax derived from petroleum and formed principally of straight-chain alkanes having average chain lengths of 20-30 carbon atoms.
Waxes comprising esters and/or acids may act as emulsifiers to the paraffins and microcrystalline waxes.
Synthetic waxes include waxes based on polypropylene, polyethylene, and polytetrafluoroethylene. Other synthetic waxes are based on fatty acid amines, Fischer Tropsch, and polyamides, polyethylene and related derivatives. Some waxes are obtained by cracking polyethylene at 400° C. The products have the formula (CH2)nH2, where n ranges between about 50 and 100.
Also outside of the building products context, in addition to waxes that occur in natural form, there are various known synthetic waxes which include synthetic polyethylene wax of low molecular weight, i.e., molecular weights of less than about 10,000, and polyethylenes that have wax-like properties. Such waxes can be formed by direct polymerization of ethylene under conditions suitable to control molecular weight. Polyethylenes with molecular weights in about the 2,000-4,000 range are waxes, and when in the range of about 4,000-12,000 become wax resins.
Fischer-Tropsch waxes are polymethylene waxes produced by a particular polymerization synthesis, specifically, a Fischer-Tropsch synthesis (polymerization of carbon monoxide under high pressure, high temperature and special catalysts to produce hydrocarbon, followed by distillation to separate the products into liquid fuels and waxes). Such waxes (hydrocarbon waxes of microcrystalline, polyethylene and polymethylene types) can be chemically modified by, e.g., air oxidation (to give an acid number of 30 or less and a saponification number no lower than 25) or modified with maleic anhydride or carboxylic acid. Such modified waxes are more easily emulsified in water and can be saponified or esterified. Other known synthetic waxes are polymerized alpha-olefins. These are waxes formed of higher alpha-olefins of 20 or more carbon atoms that have wax like properties. The materials are very branched with broad molecular weight distributions and melting points ranging about 54° C. to 75° C. with molecular weights of about 2,600 to 2,800. Thus, waxes differ depending on the nature of the base material as well as the polymerization or synthesis process, and resulting chemical structure, including the use and type of any chemical modification.
Various types of alpha-olefin and other olefinic synthetic waxes are known within the broad category of waxes, as are chemically modified waxes, and have been used in a variety of applications, outside the water-resistant wallboard area. They are of a wide variety and vary in content and chemical structure. As noted above, water-resistant wallboard products generally use paraffin, paraffin and montan, or other paraffinic or synthetic waxes as described above in the mentioned exemplary patent references. In one embodiment of the invention, the wax used for the preparation of the dispersion or emulsion is used in a micronized, pulverized form. U.S. Pat. Nos. 8,669,401 and 4,846,887 show exemplary micronization processes. Both these patents are incorporated by reference herein as if fully set forth.
In one embodiment, the emulsifiers for this invention include montan wax, esters/acids, styrene-maleic anhydride, polyolefin maleic anhydride, or other anhydrides, carnauba wax, rice wax, sunflower wax.
Theory for Colloidally-Protected Wax-Based MicrostructuresGenerally speaking, two scientific theories have been proposed to explain the stability of CPWB microstructures that comprise the emulsion materials of the present invention, namely, steric hindrance and electrostatic repulsion. Applicants do not wish to be bound by these theories, however. Applicants believe their invention relates to wax-based dispersions that may or may not relate to the two theories. It is possible that one or both theories or neither of the two may explain the CPWB microstructures of the present invention.
Alternatively, electrostatic repulsion helps with the stabilization of the colloidal dispersions. In this mechanism, the wax particle, which contains acid or ester groups (either inherently or mixed in), is first saponified with a base, converting the acid or ester groups to negatively charged carboxylate moieties. Because of their polar nature, these negatively charged carboxylate moieties exist at the water/wax interface, giving the wax particle a net negative charge. These negative charges on adjacent wax particles then constitute a repulsive force between particles that effectively stabilizes the dispersion (emulsion).
Thus, according to one model, as shown in
In another embodiment, and as shown in
The present invention applies to wax-based colloidal dispersion formulations (including the CPWB microstructure based emulsions described previously) and compositions that are amenable to the powderization process described herein. For example, the following patent references describe wax-based emulsions. These references are set forth as if full incorporated herein.
Several wax emulsion formulations are disclosed in U.S. Pat. No. 5,437,722, which are incorporated by reference herein. It describes a water-resistant gypsum composition and wax emulsion therefore, which includes a paraffin hydrocarbon having a melting point of about 40° C. to 80° C., about 1 to 200 parts by weight montan wax per 100 parts of the paraffin hydrocarbon, and about 1 to 50 parts by weight polyvinyl alcohol per 100 parts of the paraffin hydrocarbon.
U.S. Publication No. 2006/0196391 describes use of triglycerides in emulsions, and notes that the prior art has made use of petroleum waxes and synthetic waxes such as Fischer Tropsch and polyethylene waxes, which have been used for purposes similar to those of the invention of Publication 2006/0196391 with mixed results.
In the building products area, U.S. Patent Publication No 2007/0181035 A1 is directed to a composition for use in making medium density fiberboard (MDF). The composition has a component for reducing surface tension and improving dimensional stability for use in oriented strand board and MDF. The surface tension agents are either fluorinated hydrocarbon compounds of two to six carbons or alkoxylates of alkyl phenols or alkylated acetylene diols. These materials are provided to a composition having a combination of montan wax with other waxes, ammonium hydroxide for saponification, water and polyvinyl alcohol. Nonsaponifiable waxes may be used in this composition, including paraffin and scale or slack wax (which is petroleum derived). Saponifiable waxes which may be used include Montan, petroleum wax, and various natural waxes.
U.S. Patent Publication No. 2007/0245931 A1 discloses use of alkyl phenols in emulsions for water-proof gypsum board. The alkyl phenols are long-chain hydrocarbon chains having a phenolated ring of 24-34 carbon chain lengths. The publication describes use of lignosulfonic acid, and magnesium sulfate. The wax components can be combinations of paraffin and montan. The patent claims that the compositions are stable without the use of starch as in prior U.S. Pat. No. 6,663,707 of the same inventor. The wax used in the composition may be various commercially known waxes having a melting point of from about 120° F. (48.9° C.) to 150° F. (65.6° C.) with low volatility and a high molecular weight with carbon chain lengths of 36 or higher. The hydrocarbon wax component includes waxes known in the field of gypsum slurries.
U.S. Pat. No. 6,890,976 describes an aqueous emulsion for gypsum products with hydrocarbon wax, polyolefin-maleic anhydride graft polymer and polyvinyl alcohol and/or acetate. The maleic-modified material is known as FLOZOL®. The hydrocarbon wax can be paraffin or a polyethylene wax, maleated hydrocarbon wax or combinations thereof. The wax can also be a synthetic wax ester or an acid wax. The polyolefin-maleic anhydride graft copolymer is a 50-500 carbon chain graft copolymer, which when provided to the wax emulsion is described as providing improved water repellency to a final gypsum product.
U.S. Patent Publication No. 2004/0083928 A1 describes a suspension, instead of an emulsion, of various waxes in water that is mixed directly with gypsum. In describing the waxes, the suspensions can include polyethylene wax, maleated hydrocarbons and other waxes as well as wax combinations.
U.S. Pat. No. 7,192,909 describes use of polyolefin wax in an application outside the building products area, which is as a lubricant for plastics processing, specifically for PVC. The waxes are described as homopolymers and copolymers of various alpha-olefins that have been modified in a polar manner (oxidized) or grated with polar reagents. They can be used alone or in combination with other waxes, e.g. montan waxes, fatty acid derivatives or paraffins.
As described in
In the next step, said dispersion or emulsion is subjected to the drying and powderization step. Drying can be accomplished by one or more of the known drying methods such as freeze drying, vacuum drying, air drying, spray drying, atomization, evaporation, tray drying, flash drying, drum drying, fluid-bed drying, oven drying, belt drying, microwave drying, lyophilization, and solar drying. Other known drying methods that may not be listed herein, may also be used. In one embodiment, more than one method may be used to dry the colloidal dispersion.
Further as shown in
The powder resulting from step 2 in the process described above, may have an average particle size in the range of from about 1 micron to about 1,000 micron. Clearly, the larger sized particles would be agglomerates of the smaller powder emulsion particles. Theoretically, the smallest particle will be a wax particle that is covered, for example, by a hydrogen-bonded coating of a stabilizing polymeric chains of, for example, among other things, polyvinyl alcohol—
The average particle size of the powders of the present invention can be any one of the following average particle sizes, measured in microns:
1, 2, 3, 4, 5, 6, 7, 8, 9, . . . , 98, 99, 100, 101, 102, . . . , 198, 199, 200, 201, 202, . . . , 298, 299, 300, 301, 302, . . . , 398, 399, 400, 401, 402, . . . , 498, 499, 500, 501, 502, . . . , 598, 599, 600, 601, 602, . . . , 698, 699, 700, 701, 702, . . . , 798, 799, 800, 801, 802, . . . , 898, 899, 900, 901, 902, . . . , 998, 999, and 1000.
The average particle size can also be in a range that is determined by any two numbers recited above, which would include the endpoints of the range.
Alternatively, the colloidal dispersions, including the emulsions, can be dried into 2-5 mm chips, which could be regular shaped or irregular shaped. Clearly such chips would be loose agglomeration of the colloidally dispersed or emulsified particles.
In one embodiment, the particle size of the powders of the present invention is also such that 10%, 50% and/or 90% of the particles by weight are less than the following average particle size, measured in microns:
1, 2, 3, 4, 5, 6, 7, 8, 9, . . . , 98, 99, 100, 101, 102, . . . , 198, 199, 200, 201, 202, . . . , 298, 299, 300, 301, 302, . . . , 398, 399, 400, 401, 402, . . . , 498, 499, 500, 501, 502, . . . , 598, 599, 600, 601, 602, . . . , 698, 699, 700, 701, 702, . . . , 798, 799, 800, 801, 802, . . . , 898, 899, 900, 901, 902, . . . , 998, 999, and 1000.
The average particle size can also be in a range that is determined by any two numbers recited above, which would include the endpoints of the range.
Alternatively, the colloidal dispersions, including the emulsions, can be dried into 1-5 mm chips, which could be regular shaped or irregular shaped. Clearly such chips would be agglomeration of the colloidally dispersed or emulsified particles. Such chips could be of the following average particle size: 1, 1.5, 2, 2.5, 3, 3.5, 4. 4.5, and 5 mm. Such chips could also be within the range formed by any two numbers of this list including the end-points of such a range.
In one embodiment, the model shown in
Some potential applications include wax-based emulsion or dispersion as coating formulations for fuel tanks in space vehicles, or for the space craft as a whole. See for example U.S. Pat. App. No. 20080005052 which is incorporated by reference herein. The powders of the present invention potentially can be blended with high temperature organic resins (such as silicone resins) to provide high temperature heat sinks. In another example, high temperature has a disastrous effect on the longevity of batteries in electric vehicles (Tesla, Nissan Leaf, Prius, etc.). PCMs are used to address this issue. See for example http://chargedevs.com/features/allcell-technologies % E2%80%99-new-phase-change-thermal-management-material/.
The powder of the present invention can also be used in the polyurethane OEM application for spray foam. The R value of the foam should improve once the powder is added. In one embodiment, only a coating is developed that will be first applied unto a substrate (e.g., directly onto the attic frame) and then followed with a spray of regular insulating foam. The R-value of the system should then be much improved than just the PU foam alone.
In consumer products, where the outside case becomes too hot, the powder of the present invention can be applied as a coating to the inside of the outer casing, thus keeping the outer casing cool even when the water inside is boiling, e.g., a safety kettle. Other applications include astroturf (Astroturf: http://www.microteklabs.com/field-turf.html) and coatings for military desert tents, military hardware etc.
In other words, in all applications paraffin-based encapsulated PCMs are used today, the present invention provides a powder of unencapsulated wax particles that are colloidally protected in a casing by polymeric moieties such as PVOH that proves the same functionality using a variety of melt point paraffins.
An exemplary wax-based colloidal dispersion system is described herein, which can be rendered into the embodiment of the present invention, that is, a dried emulsified powder that retains some level of chemical as well as structural attributes of the colloidally dispersed (emulsified) particles.
Wax-Emulsions Including Moisture Resistant Stabilizers
Exemplary wax-based emulsions for use in a water-resistant joint compound are now described in greater detail, as follows. The wax-based emulsion can be spray dried into a powder form for subsequent use to be blended with joint compound in building construction to impart water resistance.
In one embodiment, the wax emulsion may comprise water, a base, one or more waxes optionally selected from the group consisting of slack wax, montan wax, and paraffin wax, and a polymeric stabilizer, such as ethylene-vinyl alcohol-vinyl acetate terpolymer or polyvinyl alcohol. Further, carnauba wax, sunflower wax, tall oil, tallow wax, rice wax, and any other natural or synthetic wax or emulsifier containing organic acids and/or esters can be used to form the wax emulsion. Generally, the wax emulsion may be used in the manufacture of composite wallboard. But in this case, the wax emulsion is further subjected to a powder-making step.
Water may be provided to the emulsion, for example in amounts of about 30% to about 60% by weight of the emulsion. The solids content of the wax emulsion is preferably about 40% to about 70% by weight of the emulsion. Other amounts may be used.
In some embodiments, a dispersant and/or a surfactant may be employed in the wax emulsions. Optional dispersants, include, but are not limited to those having a sulfur or a sulfur-containing group(s) in the compound such as sulfonic acids (R—S(═O)2—OH) and their salts, wherein the R groups may be otherwise functionalized with hydroxyl, carboxyl or other useful bonding groups. In some embodiments, higher molecular weight sulfonic acid compounds such as lignosulfonate, lignosulfonic acid, naphthalene sulfonic acid, the sulfonate salts of these acids and derivatized or functionalized versions of these materials are used in addition or instead. An example lignosulfonic acid salt is Polyfon® H available from MeadWestvaco Corporation, Charleston, S.C. Other dispersants may be used, such as magnesium sulfate, polycarboxylate technology, ammonium hepta molybdate/starch combinations, non-ionic surfactants, ionic surfactants, zwitterionic surfactants and mixtures thereof, alkyl quaternary ammonium montmorillonite clay, etc. Similar materials may also be used, where such materials may be compatible with and perform well with the formulation components.
In one embodiment, a dispersant and/or surfactant may comprise about 0.01% to about 5.0% by weight of the wax emulsion formulation composition, preferably about 0.1% to about 2.0% by weight of the wax emulsion formulation composition. Other concentrations may be used.
The wax component of the emulsion may include at least one wax which may be slack wax, or a combination of montan wax and slack wax. The total wax content may be about 30% to about 60%, more preferably about 30% to about 40% by weight of the emulsion. Slack wax may be any suitable slack wax known or to be developed which incorporates a material that is a higher petroleum refining fraction of generally up to about 20% by weight oil. In addition to, or as an alternative to slack wax, paraffin waxes of a more refined fraction are also useful within the scope of the invention.
Suitable paraffin waxes may be any suitable paraffin wax, and preferably paraffins of melting points of from about 40° C. to about 110° C., although lower or higher melting points may be used if drying conditions are altered accordingly using any techniques known or yet to be developed in the composite board manufacturing arts or otherwise. Thus, petroleum fraction waxes, either paraffin or microcrystalline, and which may be either in the form of varying levels of refined paraffins, or less refined slack wax may be used. Optionally, synthetic waxes such as ethylenic polymers or hydrocarbon types derived via Fischer-Tropsch synthesis may be included in addition or instead, however paraffins or slack waxes are preferred in certain embodiments. The wax emulsion used in the joint compound can be formed from slack wax, montan wax, paraffin wax, carnauba wax, tall oil, sunflower wax, rice wax, and any other natural or synthetic wax containing organic acids and/or esters, or combinations thereof. For example, synthetic wax used in the joint compound may comprise ethylenic polymers or hydrocarbon types, optionally derived via Fischer-Tropsch synthesis, or combinations thereof. Optionally, the synthetic waxes can be added in concentrations ranging from about 0.1% to about 8% of the dry weight of the joint compound or from about 0.5% to about 4.0% of the dry weight of the joint compound. In some embodiments, the wax emulsion is stabilized by polyvinyl alcohol.
Montan wax, which is also known in the art as lignite wax, is a hard, naturally occurring wax that is typically dark to amber in color (although lighter, more refined montan waxes are also commercially available). Montan is insoluble in water, but is soluble in solvents such as carbon tetrachloride, benzene and chloroform. In addition to naturally derived montan wax, alkyl acids and/or alkyl esters which are derived from high molecular weight fatty acids of synthetic or natural sources with chain lengths preferably of over 18 carbons, more preferably from 26 to 46 carbons that function in a manner similar to naturally derived montan wax are also within the scope of the invention and are included within the scope of “montan wax” as that term is used herein unless the context indicates otherwise (e.g., “naturally occurring montan wax”). Such alkyl acids are generally described as being of formula R—COOH, where R is an alkyl non-polar group which is lipophilic and can be from 18 to more than 200 carbons. An example of such a material is octacosanoic acid and its corresponding ester which is, for example, a di-ester of that acid with ethylene glycol. The COOH group forms hydrophilic polar salts in the presence of alkali metals such as sodium or potassium in the emulsion. While the alkyl portion of the molecule gets embedded within the paraffin, the acid portion is at the paraffin/aqueous medium interface, providing stability to the emulsion.
In some embodiments, the at least one wax component of the emulsion includes primarily and, preferably completely a slack wax component. In some embodiments, the at least one wax component is made up of a combination of paraffin wax and montan wax or of slack wax and montan wax. Although it should be understood that varying combinations of such waxes can be used. When using montan wax in combination with one or more of the other suitable wax components, it is preferred that montan be present in an amount of about 0.1% to about 10%, more preferably about 1% to about 4% by weight of the wax emulsion with the remaining wax or waxes present in amounts of from about 30% to about 50%, more preferably about 30% to about 35% by weight of the wax emulsion.
In some embodiments, the wax emulsion includes polyvinyl alcohol (PVOH) of any suitable grade which is at least partially hydrolyzed. The preferred polyvinyl alcohol is at least 80%, and more preferably at least 90%, and most preferably about 97-100% hydrolyzed polyvinyl acetate. Suitably, the polyvinyl alcohol is soluble in water at elevated temperatures of about 60° C. to about 95° C., but insoluble in cold water. The hydrolyzed polyvinyl alcohol is preferably included in the emulsion in an amount of up to about 5% by weight, preferably 0.1% to about 5% by weight of the emulsion, and most preferably about 2% to about 3% by weight of the wax emulsion.
In some embodiments, the stabilizer comprises a polymer that is capable of hydrogen bonding to the carboxylate or similar moieties at the water/paraffin interface. Polymers that fit the hydrogen-bonding requirement would have such groups as hydroxyl, amine, and/or thiol, amongst others, along the polymer chain. Reducing the polymer's affinity for water (and thus, its water solubility) could be achieved by inserting hydrophobic groups such as alkyl, alkoxy silanes, or alkyl halide groups into the polymer chain. The result may be a polymer such as ethylene-vinyl acetate-vinyl alcohol terpolymer (where the vinyl acetate has been substantially hydrolyzed). The vinyl acetate content may be between 0% to 15%. In some embodiments, the vinyl acetate content is between 0% and 3% of the terpolymer chain. The ethylene-vinyl alcohol-vinyl acetate terpolymer may be included in the emulsion in an amount of up to about 10.0% by weight, preferably 0.1% to about 5.0% by weight of the emulsion. In some embodiments, ethylene-vinyl alcohol-vinyl acetate terpolymer may be included in the emulsion in an amount of about 2% to about 3% by weight of the wax emulsion. An example ethylene-vinyl alcohol-vinyl acetate terpolymer that is available is the Exceval AQ4104™, available from Kuraray Chemical Company.
The wax emulsion may include a stabilizer material (e.g., PVOH, ethylene-vinyl alcohol-vinyl acetate terpolymer as described above). The stabilizer may be soluble in water at elevated temperatures similar to those disclosed with reference to PVOH (e.g., about 60° C. up to about 95° C.), but insoluble in cold water. The active species in the wax component (e.g., montan wax) may be the carboxylic acids and esters, which may comprise as much as 90% of the wax. These chemical groups may be converted into carboxylate moieties upon hydrolysis in a high pH environment (e.g., in an environment including aqueous KOH). The carboxylate moieties may act as a hydrophilic portion or “head” of the molecule. The hydrophilic portions can directly interface with the surrounding aqueous environment, while the rest of the molecule, which may be a lipophilic portion or “tail”, may be embedded in the wax.
A stabilizer capable of hydrogen bonding to carboxylate moieties (e.g., PVOH or ethylene-vinyl alcohol-vinyl acetate terpolymer as described above) may be used in the wax emulsion. The polar nature of the carboxylate moiety may offer an optimal anchoring point for a stabilizer chain through hydrogen bonding. When stabilizer chains are firmly anchored to the carboxylate moieties as described above, the stabilizer may provide emulsion stabilization through steric hindrance. In embodiments where the wax emulsion is subsequently dispersed in a wallboard (e.g., gypsum board) system, all the water may be evaporated away during wallboard manufacture. The stabilizer may then function as a gate-keeper for repelling moisture. Decreasing the solubility of the stabilizer in water may improve the moisture resistance of the wax emulsion and the wallboard. For example, fully hydrolyzed PVOH may only dissolve in heated, and not cool, water. For another example, ethylene-vinyl alcohol-vinyl acetate terpolymer may be even less water soluble than PVOH. The ethylene repeating units may reduce the overall water solubility. Other stabilizer materials are also possible. For example, polymers with hydrogen bonding capability such as those containing specific functional groups, such as alcohols, amines, and thiols, may also be used. For another example, vinyl alcohol-vinyl acetate-silyl ether terpolymer can be used. An example vinyl alcohol-vinyl acetate-silyl ether terpolymer is Exceval R-2015, available from Kuraray Chemical Company. In some embodiments, combinations of stabilizers are used.
In some embodiments, the wax emulsion comprises a base. For example, the wax emulsion may comprise an alkali metal hydroxide, such as potassium hydroxide or other suitable metallic hydroxide, such as aluminum, barium, calcium, lithium, magnesium, sodium and/or zinc hydroxide. These materials may serve as saponifying agents. Non-metallic bases such as derivatives of ammonia as well as amines (e.g., diethanolamine or triethanolamine) can also be used. Combinations of the above-mentioned materials are also possible. If included in the wax emulsion, potassium hydroxide is preferably present in an amount of 0% to 1%, more preferably about 0.1% to about 0.5% by weight of the wax emulsion.
In some embodiments, an exemplary wax emulsion comprises: about 30% to about 60% by weight of water; about 0.1% to about 5% by weight of a lignosulfonic acid or a salt thereof; about 0% to about 1% by weight of potassium hydroxide; about 30% to about 50% by weight of wax selected from the group consisting of paraffin wax, slack wax and combinations thereof; and about 0.1% to about 10% montan wax, and about 0.1 to 5% by weight of ethylene-vinyl alcohol-vinyl acetate terpolymer.
The wax emulsion may further include other additives, including without limitation additional emulsifiers and stabilizers typically used in wax emulsions, flame retardants, lignocellulosic preserving agents, fungicides, insecticides, biocides, waxes, sizing agents, fillers, binders, additional adhesives and/or catalysts. Such additives are preferably present in minor amounts and are provided in amounts which will not materially affect the resulting composite board properties. Preferably no more than 30% by weight, more preferably no more than 10%, and most preferably no more than 5% by weight of such additives are present in the wax emulsion.
Shown in the below tables are example embodiments of a wax emulsion, although other quantities in weight percent may be used.
The wax emulsion may be prepared using any acceptable techniques known in the art or to be developed for formulating wax emulsions, for example, the wax(es) are preferably heated to a molten state and blended together (if blending is required). A hot aqueous solution is prepared which includes any additives such as emulsifiers, stabilizers, etc., ethylene-vinyl alcohol-vinyl acetate terpolymer (if present), potassium hydroxide (if present) and lignosulfonic acid or any salt thereof. The wax is then metered together with the aqueous solution in appropriate proportions through a colloid mill or similar apparatus to form a wax emulsion, which may then be cooled to ambient conditions if desired.
In some embodiments, the wax emulsion may be incorporated with or coated on various surfaces and substrates. For example, the wax emulsion may be mixed with gypsum to form a gypsum wallboard having improved moisture resistance properties.
Some or all steps of the above method may be performed in open vessels. However, the homogenizer may use pressure in its application.
Advantageously in some embodiments, the emulsion, once formed, is cooled quickly. By cooling the emulsion quickly, agglomeration and coalescence of the wax particles may be avoided.
In some embodiments the wax mixture and the aqueous solution are combined in a pre-mix tank before they are pumped into the colloid mill or homogenizer. In other embodiments, the wax mixture and the aqueous solution may be combined for the first time in the colloid mill or homogenizer. When the wax mixture and the aqueous solution are combined in the colloid mill or homogenizer without first being combined in a pre-mix tank, the two mixtures may advantageously be combined under equivalent or nearly equivalent pressure or flow rate to ensure sufficient mixing.
In some embodiments, once melted, the wax emulsion is quickly combined with the aqueous solution. While not wishing to be bound by any theory, this expedited combination may beneficially prevent oxidation of the wax mixture.
Water-Resistant Products Comprising Wax-Based Colloidal Dispersion Powders
Embodiments of the disclosed wax-based colloidal dispersions (comprising CPWB microstructures) can be used to form many different water-resistant products. For example, embodiments of powders made from wax emulsion disclosed above can be used to form a water-resistant joint compound. The joint compound can be used to cover, smooth, or finish gaps in boards, such as joints between adjacent boards, screw holes, and nail holes. The joint compound can also be used for repairing surface defects on walls and applying texture to walls and ceilings amongst numerous other applications. The joint compound can also be specially formulated to serve as a cover coat on cement and concrete surfaces. The joint compound can be particularly useful in locations where there is high humidity, such as bathrooms, to prevent molding or other deleterious effects.
Also, embodiments of powders formed from wax emulsion described above can be incorporated into building materials such as asphalt (e.g., comprising a viscous liquid or semi-solid form of petroleum), concrete (e.g., comprising aggregate or filler, cement, water, various chemical and/or mineral admixtures, etc.), stucco, cement (e.g., formed from or comprising calcium carbonate, clay, gypsum, fly ash, ground granulated blast furnace slag, lime and/or other alkalis, air entertainers, retarders, and/or coloring agents) or other binders. In some embodiments, powders formed from the wax emulsion can be incorporated into concrete cover coat formulations, such as those used for filling, smoothing, and/or finishing interior concrete surfaces, drywall tape, bead embedment, skim coating, and texturing drywall. Further, embodiments of the wax emulsion can be incorporated into concrete and/or cement mixtures as a water repellent additive. Therefore, embodiments of the powders formed from wax emulsion can be incorporated into pourable concrete and/or cement that can be used, for example, for foundations in home constructions. Additionally, embodiments of the powders formed from wax emulsion can be used in cinder blocks as well as other similar concrete or cement based products.
Embodiments of the powders formed from wax emulsion can also be incorporated into boards, such as cement boards (e.g., a relatively thin board, comprising cement bonded particle boards and cement fiber (e.g., comprising cement, fillers, cellulose, mica, etc.), which may be 0.25-0.5 inch thick or which may be thicker or thinner), and/or cement board formulations. Therefore, the wax emulsion can be used to provide additional water resistance of the boards, and potentially prevent water or water vapor from penetrating the boards.
Additionally, powders formed from embodiments of the wax emulsion can be incorporated into paint and/or paint formulations (e.g. a liquid, liquefiable, or mastic composition that, after application to a substrate in a thin layer, converts to a solid film), such as paint that may be used to protect, color, or provide texture to a substrate. This can be done to impart water repellency, or water resistance, to the paint. The type of paint is not limiting, and embodiments of the wax emulsion can be incorporated into oil, water, acrylic, or latex based paints, including paints that may be pigmented to add color to the substrate on which the paint is applied. This water resistant paint can then be used on exterior and interior surfaces of buildings, as well as other products such as vehicles (e.g. cars, boats, and planes), toys, furniture.
While the above detailed description has shown, described, and pointed out features as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the devices or algorithms illustrated can be made without departing from the spirit of the disclosure. For example, certain percentages and/or ratios of component ingredients have been described with respect to certain example embodiments; however, other percentages and ratios may be used. Certain process have been described, however other embodiments may include fewer or additional states. As will be recognized, certain embodiments of the inventions described herein can be embodied within a form that does not provide all of the advantages, features and benefits set forth herein, as some features can be used or practiced separately from others.
EXPERIMENTAL Examples 1-7Aqualite® 484 which is an emulsion from the Henry Company was spray dried to form particulate material from the emulsion. Aqualite® 484 emulsion was added directly to a 300-gallon mixing tank with moderate agitation. The solids content of the emulsion was also calculated. A solids result of 40.5% for the liquid was found. From the mixing tank, the emulsion was fed to the drying chamber of the spray drying equipment through a two-fluid internal mix spray nozzle. The second fluid used was air (at multiple pressures) to atomize the liquid into droplets. From the drying chamber, powder was conveyed to a baghouse system. Powder was collected directly from the baghouse and sifted through a 10-mesh screen to remove any oversized powder agglomerates from the final product. No inorganic flow agent was used during this trial. The product was packaged in drums. The weight of each drum was dependent on how often a dryer condition was changed. The powder samples were all tested for moisture content, particle size, and bulk density. Drying was performed at temperature between 115° F. and 140° F. (inlet) and 175° F. and 200° F. (outlet) and an atomization pressure of 120-130 psi. The melting point of the product is 140° F. The moisture content of the finished product was 1.26%. Particle size was measured for each test. The results are tabulated in Table 3. The D(10) particle size indicates the biggest average particle size that covers 10% of the material. D(50) indicates the average particle size below which 50% of the particles are found.
Claims
1. A process for preparing a powder from a wax-based colloidal dispersion comprising CPWB microstructres, comprising:
- (A) providing at least one wax-based colloidal dispersion;
- (B) subjecting said wax-based colloidal dispersion to at least one powder-making process; and
- (C) optionally subjecting the resulting powder from step (B) to a size reduction process;
- wherein said wax-based colloidal dispersion emulsion is optionally subjected to additional drying before, during, or after said at least one powder-making process.
Type: Application
Filed: Feb 5, 2021
Publication Date: May 27, 2021
Inventor: Amba Ayambem (Glenmoore, PA)
Application Number: 17/168,744
