Background of the Invention

Currently, most polyurethane (PU) synthetic leathers, and many anticorrosion coatings are made using organic solvents, such as dimethylformamide, methylethyl ketone ( EK) and toluene. These solvents vaporize during manufacture and post manufacturing, which leads to potential health issues for the manufacturing staff, the end users of the synthetic leather or anticorrosion coating, and the environment.

As a result, in the synthetic leather area, the European standard for the organic solvent PU based synthetic leather was changed to require less than 10 ppm DMF in the leather. However, making such leathers is a challenge using organic solvent based methodologies. As a result, the use of solvent free or water borne PU (also known as polyurethane dispersion or PUD) has received some attention, as it uses little, if any, organic solvent.

Likewise, solvent based anticorrosion coatings are widely used throughout the world and are known to use millions of tons of organic solvents in their preparation. As a result, the United States has passed laws, such as the Clean Air Act, which seeks to reduce the amount of organic solvents released into the atmosphere and the environment.

While studying various PUDS for use in industrial settings, such as in the use of synthetic leathers, dried PUD films and/or anticorrosion coatings, it was discovered that materials made from PUDs containing CaC0 ₃ nanoparticles that were surface treated with stearic acid surprisingly and unexpectedly had improved tensile strength and elongation characteristics, relative to materials that did not contain nanoparticles. As a result, they are more durable than other PUDs and are useful in the preparation of synthetic leathers, dried PUD films, and anticorrosive coatings.

Summary of the Invention

In one aspect, disclosed herein are methods for producing a material from a polyurethane dispersed in water (PUD) that contains nanoparticles (preferably, CaC0 ₃ nanoparticles that were surface treated with stearic acid), wherein said material has improved elongation, tensile strength, and stability, relative to other materials made from PUDs that do not contam nanoparticles (such as CaC0 ₃ nanoparticles that were surface treated with stearic acid), the methods comprising:

preparing a polyurethane prepolymer, wherein the prepolymer comprises at least one isocyanate resin, and at least one polyol;

preparing a first mixture comprising the polyurethane prepolymer, at least one surfactant, and at least one nanoparticle;

preparing a second mixture comprising, the first mixture, water, and a chain extender; and

curing the second mixture.

In another aspect, disclosed herein are methods for producing a polyurethane dispersed in water (PUD) having improved tensile strength, the method comprising:

preparing a polyurethane prepolymer, wherein the prepolymer comprises at least isocyanate resin, and at least one polyol;

preparing a first mixture comprising the polyurethane prepolymer, at least one surfactant, and at least one nanoparticle; preparing a second mixture comprising, the first mixture, water, and a chain extender; and

curing the second mixture, In another aspect, disclosed herein are methods for producing a polyurethane dispersed in water (PUD) having improved elongation, the method comprising:

preparing a polyurethane prepolymer, wherein the prepolymer comprises at least one isocyanate resin, and at least one polyol;

preparing a first mixture comprising the polyurethane prepolymer, at least one surfactant, and at least one nanop rticle;

preparing a second mixture comprising, the first mixture, water, and a chain extender; and

curing the second mixture. Also disclosed herein are dried PUD films, synthetic leathers and anticorrosion materials made according to the above methods.

Methods of using the dried PUD films, synthetic leathers and anticorrosion materials are also described herein.

Detailed Description

The following discussion applies to the leathers, anticorrosion coatings, dried PUD films, and methods described herein.

In one embodiment, the polyurethane prepolymer comprises an isocyanate resin, and the at least one nanoparticle added to the polyurethane prepolymer, the first mixture, or both. Typically, the nanoparticle is added to the first mixture and preferably, it is added before the formation of the second mixture.

The isocyanates used herein contain at least two isocyanate groups and include organic diisocyanates, which may be aromatic, aliphatic, or cyclo aliphatic, or a combination thereof. Representative examples of suitable diisocyanates include 4,4'- diisocyanatodiphenylmethane, 2,4'-diisocyanatodiphenylmethane, isophorone diisocyanate, p-phenylene diisocyanate, 2,6 toluene diisocyanate, polyphenyl polymethylene

polyisocyanate, 1 ,3-bis(isocyanatomethyl)cyclohexane, 1 ,4-diisocyanatocyclohexane, hexamethylene diisocyanate, 1,5 -naphthalene diisocyanate, 3,3'~dimethyl-4,4'-biphenyl diisocyanate, 4,4 '-dii so cyanatodicyclohexylmethane, 2,4'-diisocyanatodicyclohexylmethane, and 2,4-toluene diisocyanate, or combinations thereof. More preferred diisocyanates are 4,4'-diisocyanatodicyclohexylmethane, 4,4'-diisocyanatodiphenylmethane, 2,4'- diiso cyanatodicyclohexylmethane, and 2,4'-diisocyanatodiphenylmethane. Most preferred are isophorone diisocyanate; 4,4'-diisocyanatodiphenylmethane (also known as 4,4'-MDI); and 2,4'-diisocyanatodiphenylmethane (also known as 2,4'-MDI). The isocyanates may be purified or part of a mixture of one or more isocyanates. If an isocyanate is a solid, it may be melted and/or dissolved in a solvent before it used. .All of the methods and leathers disclosed herein comprise at least one nanoparticle.

Nanoparticles are particles with dimensions between 1 and 100 nanometers and are known in the art. As used herein, nanoparticles include mixtures of various particle sizes, which are typically in the 10-90 ran range. Examples of nanoparticles include CaC0 ₃ , Ti0 ₂ and Si0 ₂ . If desired, the surface of the nanoparticle may be modified with a compound in order to change the nanoparticles characteristics. For example, CaC0 ₃ may be made less hydrophihc by surface treatment with one or more fatty acids, acrylic acids, resin acids, stearic acid, boric acid esters, etc. When making CaC0 ₃ less hydrophilic, it is important to use a surface treating molecule that has a hydrophobic tail. Nanoparticles of CaC0 ₃ that have been surface modified with stearic acid have been used to increase the stiffness and toughness of polypropylene (see CM. Chan, J.S. Wu, J.X. Li, Y.K. Cheung, Polymer, 43 (2002), pp. 2981-2992.) and are preferred. If desired mixtures of different nanoparticles may be used. In one embodiment, the nanoparticle is CaC0 ₃ (surface modified with stearic acid), T1O2, Si0 ₂ , or a combination thereof. A preferred nanoparticle (when used alone or in combination with other nanoparticles) is CaC0 ₃ (surface modified with stearic acid)

Typically, the nanoparticles are present in 0.1 to 10%, based on the solid content of the PUD. More preferably, the nanoparticles comprise 0.3 to 7% of the solid content of the PUD.

And while the nanoparticles may be added to the prepolymer, the first mixture, and/or the second mixture, it is preferred to add the nanoparticles to the prepolymer and/or the first mixture. Typically, the leathers, dried PUD films, anticorrosion coatings, and methods disclosed herein comprise 0.1-15 % by weight (based on the weight of the dried the leathers, dried PUD films, or anticorrosion coatings,) of nanoparticles. More preferably, the leathers, dried PUD films, anticorrosion coatings, and methods disclosed herein comprise 0.1-10 % by weight nanoparticles; still more preferably, 0.3-7 % by weight nanoparticles.

The term "surfactants," as used herein, refers to any compound that reduces surface tension when dissolved in water or water solutions that reduces interfacial tension between two liquids. Surfactants useful for preparing a stable dispersion in the practice of the present invention may be cationic surfactants, anionic surfactants, zwitterionic, or a non-ionic surfactants. Examples of anionic surfactants include, but are not limited to, sulfonates, carboxylates, and phosphates. Examples of cationic surfactants include, but are not limited to, quaternary amines. Examples of non-ionic surfactants include, but are not limited to, block copolymers containing ethylene oxide and silicone surfactants, such as ethoxylated alcohol, ethoxylated fatty acid, sorbitan derivative, lanolin derivative, ethoxylated nonyl phenol or alkoxylated polysiloxane. Furthermore, the surfactants can be either external surfactants or internal surfactants. External surfactants are surfactants which do not become chemically reacted into the polymer during dispersion preparation. Examples of external surfactants useful herein include, but are not limited to, salts of dodecyl benzene sulfonic acid, and lauryl sulfonic acid salt. Internal surfactants are surfactants which do become chemically reacted into the polymer during dispersion preparation. Examples of an internal surfactant useful herein include, but are not limited to, 2,2-dimethylol propionic acid

(DMPA) and its salts, quatemized ammonium salts, and hydrophilic species, such

polyethylene oxide polyols.

Specific examples of surfactants include, for example, DABCO™ DC 193 (supplied by Air Products), which has Polydimethylsiloxane (PDMS) backbone and polyethylene oxide-co-propylene oxide (PEO-PPO) random copolymer grafts; TEGOSTAB™ B8488 (supplied by Evonik), which has a polydimethylsiloxane (PDMS) backbone and

polyethylene oxide-co-propylene oxide (PEO-PPO) random copolymer grafts with viscosity of 1000 cPs, insoluble in water; TEGOSTAB™ B8526 (supplied by Evonik), which has a polydimethylsiloxane (PDMS) backbone and polyethylene oxide-co-propylene oxide (PEO- PPO) random copolymer grafts with viscosity of 3000 cPs, insoluble in water;

TEGOSTAB™ B8535 (supplied by Evonik), which has a Polydimethylsiloxane (PDMS) backbone and polyethylene oxide-co-propylene oxide (PEO-PPO) random copolymer grafts with viscosity of 1200 cPs, Cloud point of 59C; and VORASURF™ 504 (supplied by The Dow Chemical Company), which is a polyethylene oxide-co-butylene oxide triblock organic surfactant with equivalent weight of 3400 and nominal viscosity of 3300 cPs at 25C, ammonium stearate, disodium octadecyl sulfosuccinimate, cocamidopropyl betaine, sodium dodecylbenzene sulfonate (RHODACAL DS-4, supplied by Rhodia), triethanolamine dodecylbenzene sulfonate, and sodium alpha olefin sulfonate. If desired, mixtures comprising more than one surfactant may be used.

Preferred surfactants in the first mixture are external surfactants. It is preferred that all surfactants in the first mixture be external surfactants. In one embodiment, preferred external surfactants in the first mixture are sulfonate or sulfonic acid based. More specifically, preferred surfactants in the first mixture include sodium dodecylbenzene sulfonate, triethanolamine dodecylbenzene sulfonate, and sodium alpha olefin sulfonate. One especially preferred surfactant in the first mixture is sodium dodecylbenzene sulfonate.

If at least one surfactant is not used with the nanoparticle, it is not possible to make the PUD.

Chain extenders are always used when making the synthetic leathers, anticorrosion coatings, and dried PUD films disclosed herein. Chain extenders are bifuncational or polyfuncational, low molecular weight (typically weighing from 18 up to 500 g/mol) compounds that contain at least two active hydrogen containing groups. Any chain extender known to be useful to those of ordinary skill in the art of preparing polyurethanes can be used in the synthetic leathers, anticorrosion coatings, dried PUD films and methods disclosed herein. Examples of chain extenders include diols, polyols, diamines, polyamines, hydrazides, acid hydrazides, and water. Of these, amine containing chain extenders and water are preferred. Furthermore, one or a combination of chain extenders may be used. For example, the chain extender may be mixed with or otherwise contain water.

Examples of chain extenders include water, piperazine, 2-methylpiperazine; 2,5- dimethylpiperazine; 1 ,2-diaminopropane; 1 , 3-diaminopropane; 1 ,4-diaminobutane; 1,6- diaminohexane, isophorone diamine, mixtures of isomers of 2,2,4- and 2,4,4-trimethyl hexamethylene diamine, 2-methyl pentamethylene diamine, diethylene triamine, dipropylenetriamine, triethylenetetramine, 1,3- and 1,4-xylylene diamine, a _; a,a',a'- tetramethyl-1,3- and -1,4-xylylene diamine and 4,4'-dicyclohexylmethanediamine, 3,3'- dimethyl-4,4'-dicyclohexylmethanediamine, 1 ,2-cyclohexanediamine; 1 ,4- cyclohexanediamine, dimethyl ethylene diamine, hydrazine or adipic acid dihydrazide ethylene glycol; ethylene oxide; propylene oxide; ammoethylethanolamine (AEEA);

aminopropylethanolamine, aminohexylethanolamine; aminoethylprop anolamine, aminopropylpropanolamine, aminohexylpropanolamine; cyclohexane dimethanol;

hydroquinone bis(2-hydroxyethyl)ether (also known as HQEE); ethanolamine;

diethanolamine; piperazine, JEFFAMINE D-230 (a polyether with two amino terminating groups, having a molecular weight of approximately 230 that is sold by the Huntsman Co.) , methyldiethanolamine; phenyldi ethanolamine; diethyltoluenediamine,

dimethylthiotoluenediamine and trimethylolpropane. Particularly preferred chain extenders include water, AEEA, piperazine and 1 ,4-diaminobutane. The typical ratio of the NCO in the prepolymer to the diamine chain extender is 8:1.

In one embodiment, two chain extenders are used. In such a situation, the first chain extender is water, and the second chain extender may be a diamine or polyamine based compound. Preferred diamines for use in this embodiment include piperazine and 1 ,4- diaminobutane, with 1 ,4-diaminobutane being the most preferred. When two chain extenders are used, they may be added simultaneously to the mixture, or sequentially.

The methods, synthetic leathers, anticorrosion coatings, and dried PUD films disclosed herein utilize at least two polyols, wherein the polyols are polyether polyols, polyester polyols, aromatic polyols, or combinations thereof. Polyols include one or more other polyether or polyesters polyols of the kind typically employed in processes to make polyurethanes. Other compounds having at least two isocyanate reactive hydrogen atoms may also be present, for example polythioether polyols, polyester amides and polyacetals containing hydroxyl groups, aliphatic polycarbonates containing hydroxyl groups, amine terminated polyoxyalkylene polyethers, and preferably, polyester polyols, polyoxyalkylene polyether polyols, and graft dispersion polyols. Mixtures of two or more of the aforesaid materials may also be employed. In one preferred embodiment, the mixture of at least two polyols comprises at least one polyether polyol, and at least one polyester polyol.

The term "polyester polyol" as used herein includes any minor amounts of unreacted polyol remaining after the preparation of the polyester polyol and/or unesterified polyol (for example, glycol) added after the preparation of the polyester polyol. Suitable polyester polyols can be produced, for example, from aliphatic organic dicarboxylic acids with 2 to 12 carbons, preferably aliphatic dicarboxylic acids with 4 to 6 carbons, and multivalent alcohols, preferably diols, with 2 to 12 carbons. Examples of aliphatic dicarboxylic acids include succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, and terephthalic acid. The corresponding dicarboxylic acid derivatives may also be used such as dicarboxylic acid mono-or di-esters of alcohols with 1 to 4 carbons, or dicarboxylic acid anhydrides. Examples of divalent and multivalent alcohols, especially diols, include ethanediol, diethylene glycol, glycerine and trimethylolpropanes or mixtures of at least two of these diols. Polyester polyols derived from vegetable oils (natural oil polyols or NOPs) may also be used.

Useful aromatic polyols include aromatic polyether polyol or an aromatic polyester polyol or combinations of the two. Particularly desirably aromatic polyester polyol is an aromatic dicarboxylic acid with 8 to 24 carbons. While the aromatic polyester polyols can be prepared from substantially pure aromatic dicarboxylic acids, more complex ingredients are advantageously used, such as the side stream, waste or scrap residues from the manufacture of phthalic acid, terephthalic acid, dimethyl terephthalate, and polyethylene terephthalate. Other residues are dimethyl terephthalate (DMT) process residues, which are waste or scrap residues from the manufacture of DMT. The present applicants have observed that for certain applications it is particularly advantageous for reasons of foam performance and processing to have present in the polyol composition both the "Novolac" polyol and an additional aromatic polyol which can be an aromatic polyether or aromatic polyester polyol.

Polyether polyols are compounds that have an ether backbone and further comprise at least two OH groups. Polyether polyols are commonly made by reacting monomelic compounds (either alone or in combination), such as glycerine (a triol), pentaerythritol (a tetraol), ethylene glycol (a diol), diethylene glycol (a diol of the formula:

HOCH ₂ CH ₂ 0CH ₂ CH ₂ 0H), and/or sucrose with ethylene oxide, propylene oxide and/or butylene oxide in the presence of an initiator and/or a catalyst. Suitable initiators include aliphatic and aromatic amines, such as monoethanolamine, vicinal toluenedi amines, ethylenediamines, and propyl enediamine. Useful catalysts include strong bases, such as NaOH, or KOH, and double metal cyanide catalysts, such as zinc hexacyanocobalt-t- butanol complex. Common polyether polyols include polyethylene glycol (PEG), polypropylene glycol, and poly(tetramethlene ether)glycol. Preferred polyether polyols are comprised of monohydroxyl polyethylene oxide units. In a preferred embodiment, at least one of the polyols used herein is a polyether polyol having an average molecular weight of 400 to 1500 g/mol.

Some preferred polyols include VORANOL 9287 A (a 2000 molecular weight, 12 percent ethylene oxide capped diol stabilized with alkyldiphenylamine, a product of The Dow Chemical Company); CARBOWAX Polyethylene Glycol (PEG) 1000 (CAS # 25322- 68-3, a 1000 molecular weight, polyethylene glycol monomethyl ether, >= 99.0 %, a product of The Dow Chemical Company); Bester 48 (a polyester polyol having a molecular weight of approximately 1,000, it is an ethylene glycol/butane diol/adipic acid (EG/BD/AA) type polyol that is a product of The Dow Chemical Company); Bester 104 (a DEG/IPA/AA based polyester polyol, i.e., a diethylene glycol/isopropyl alcohol/adipic acid based polyester polyol ); PEG 400 (a 400 molecular weight, polether polyol based on ethylene oxide that is a product of the Sinopharm Chemical Reagent Corporation, Shanghai, China); PPG 425 (a propylene oxide based polyether polyol have a molecular weight of 425 that is a product of The Dow Chemical Company); and DEG (diethylene glycol, which is sold by Sigma).

The polyols used in the methods, synthetic leathers, anticorrosion coatings, and dried PUD films described herein typically weigh less than 5,000 g/mol. More preferably, the polyols weigh less than 4,000 g/mol, with polyols having a molecular weight of less than 3,000 g/mol being even more preferred. Still more preferably, each polyol has an average molecular weight of less than 2000 g mol.

The use of a strong base catalyst to make a polyether polyol often causes the polyether polyol to be too basic, which has a detrimental effect on the aforementioned prepolymer. Consequently, it is often necessary to treat the polyether polyol with a scavenger compound, which reacts with the residual base and makes the prepolymer more acidic. Suitable scavenger compounds include benzoyl chloride, and 85% phosphoric acid, with benzoyl chloride being preferred. Typically, adding aqueous acids introduces excess water into the prepolymer, which will react with the isocyanate and adversely impact the resulting synthetic leathers, anticorrosion coatings, and dried PUD films. The inventors typically use a scavenger compound to adjust the net controlled polymerization rate of the mixture to be lower than -10. ASTM D 6437 - 05 corresponds to the CPR procedure. In one embodiment, the methods and resulting products at least two polyols, wherein one polyol is a polyester polyol and the other is a polyether polyol. Alternatively, the two polyols are both polyether polyols.

In another embodiment, the methods and resulting products utilize three polyols, wherein one polyol is a polyester polyol and the other two are polyether polyols.

Alternatively, 1) two polyols are polyester polyols, while one polyol is a polyether polyol; 2) all three polyols are polyether polyols; or 3) all three polyols are polyester polyols.

In still another embodiment, the methods and resulting products utilize four or more polyols. In such cases any combination of polyols may be used. Preferably, the

polyurethane prepolymer contains less than five polyols.

In the methods and resulting products disclosed herein, the weight ratio of the polyols to the isocyanate resin in the prepolymer is typically 1 :1 to 4: 1. Preferably, the weight ratio is 1 : 1 to 3 : 1. More preferably, the weight ratio is 2: 1 to 3 : 1.

The weight ratio of the surfactant to the combined weight of the polyols and the isocyanate(s) is 1 :5 to 0.01 :5. More preferably this ratio is 0.3 :5 to 0.1 :5.

The weight ratio of water to the combined weights of the polyols, the isocyanate(s), surfactants and chain extender(s) is 25:75 to 99:1. More preferably, the ratio is 40:60 to 60:40.

In one embodiment, the polyurethane prepolymer is made by combining a liquid isocyanate resin and at least two liquid polyols. If necessary, solid isocyanate may be melted to form the liquid isocyanate resin.

In another embodiment, the polyurethane prepolymer is made by melting the isocyanate resin, heating the at least one polyol and then combining the melted isocyanate resin and the heated at least one polyol. Preferably, the melted isocyanate is combined with a mixture comprising at least two polyols, wherein the polyol mixture is heated to 50-90 °C before it is combined with the melted isocyanate. More preferably, the polyol mixture is heated to a temperature that is at least 60 °C; still more preferably, it is heated to at least 70 °C, with 80 °C being particularly preferred. If all reagents are liquids or if a solid reagent is soluble in the other liquid reagents, then the preheating of the polyol mixture is optional. When the isocyanate resin and or the polyols are solids, it may be necessary to melt the resin and/or polyols before mixing them. For example, it may be necessary to melt the isocyanate resin, heat the at least one polyol and then combine the melted isocyanate resin and the heated at least one polyol. The at least one polyol should be heated to a temperature that is higher than the melting point of the isocyanate resin. Thus, when the melted isocyanate resin and polyol(s) are combined, the mixture does not solidify. In at least one embodiment, the isocyanate resin is melted before being combined with at least one polyol.

The methods and resulting products described herein require drying or otherwise treating/curing the PUD before it can be used. Any method known in the art, such as using UV light and/or heat may be used. Generally, heating takes place as quickly as practicable to fix the desired cell structure. The curing temperature may be any temperature suitable so long as the PUD does not decompose. The heating time is desirably as short as practicable. Typical heating times range between seconds up to 1 hour. Any suitable heating method or heating energy source may be used such as a convection oven, heating plates, infrared oven, microwave heating or combination thereof. Suitable drying conditions include 1) maintaining a constant temperature until dry, 2) using a temperature gradient wherein the temperature changes over time, or 3) using a multistep drying regime where the temperature is held for a set amount of time and then changed to a different temperature, which is then held for a set amount of time (3, 4, 5, or more drying steps may also be used), The drying times for each step may be the same or different. Typical drying times are from a few seconds up to one hour. Typical drying temperatures are in the range of at least 50 °C and no more than 250 °C. Preferably the temperature is at least about 75° C, more preferably at least about 90° C. In one embodiment, the temperature is 90-190 ⁰ C. and most preferably at most 170° C. One preferred example of a suitable drying protocol when preparing synthetic leathers, anticorrosion coatings, and dried PUD films is to subject the to be dried PUD to a temperature of 95-105 °C for 4-10 minutes and then to a temperature of 165-175 °C for 3-10 minutes. During the drying process, the water evaporates and the PUD sets (which may include melting of at least some of the PUD) and thereby forms the final coating. The drying process should not cause decomposition of the PUD.

Typically, the drying is performed in an oven at atmospheric pressure, but it can be performed at pressures above or below atmospheric pressure.

The methods and resulting products described herein utilize a PUD mixture that may further comprise additional additives as is known in the art. Examples of suitable additives include N,N-dimethylethanolamine, fillers (such as wood fibers, Si0 ₂ , Ti0 ₂ , magnesium oxide, aluminium oxide, Talc, and/or glass beads), a thickener, a flame retardant, a pigment, a flowing additive, additive, antioxidant, anti-UV additive, antistatic agent, antimicrobial agent, or combinations thereof. In one embodiment, at least one of the aforementioned additives is present.

The aforementioned fillers, when present, account for 0.1 -50 % by weight of the composition (excluding the fabric). More preferably, when present, the fillings account for 0.1 - 40 % by weight of the composition. Still more preferably, the fillers account for 0.1 - 30 % by weight of the composition.

The non-filler additives, i.e., the aforementioned additives, not including the fillers, typically account for 0.01-20 % by weight of the composition. More preferably, the non- filler additives account for 0.1-10 % by weight of the composition. Still more preferably, the non-filler additives account for 1 -5 % by weight of the composition. Flowing additives, additives, antioxidants, anti-UV additives, antistatic agents, and antimicrobial agents are typically comprise less than 5% by weight of the composition. The additives may be added to the polyester polyol modified PUD, to the mixture comprising the polyester polyol modified PUD or combinations thereof.

In one embodiment, the first mixture, the second mixture, or both further comprise at least one of Si0 ₂ or Ti0 ₂ .

Examples of pigments, include Ti0 ₂ , carbon black and other, known pigments.

Pigments are well known in the art and typically present in less than 10% by weight, based on the dried weight of the synthetic leathers, anticorrosion coatings, and dried PUD films.

Examples of flame retardants that may be used in the synthetic leathers,

anticorrosion coatings, dried PUD films and methods disclosed herein include those typically used to give enhanced flame retardant properties to a typical latex foam. Such flame retardants include phosphonate esters, phosphate esters, halogenated phosphate esters or a combination thereof. Representative examples of phosphonate esters include

dimethylphosphonate (DMMP) and diethyl ethylphosphonate (DEEP). Representative examples of phosphates esters include triethyl phosphate and tricresyl phosphate. When used the phosphonate or phosphate ester flame retardants are present in the final foam at a level of from 0.5 to 10 percent by weight of the final foam.

Representative examples of halogenated phosphate esters include 2-chloroethanol phosphate (C ₆ H ₁₂ C1 ₂ 0 ₄ P); 1 -chloro-2-propanol phosphate [tris(l -chloro-2-propyl) phosphate] (C ₉ H _]8 C1 ₃ 0 ₄ P) (TCPP); l,3-Dichloro-2-Propanol Phosphate (C ₉ H ₁₅ C1 ₆ 04P) also called tris(l,3-dichloro-2-propyl) phosphate; tri(2-chloroethyl) phosphate; tri (2,2- dichloroisopropyl) phosphate; tri (2,3-dibromopropyl) phosphate; tri(l,3- dichloropropyl)phosphate; tetrakis(2-chloroethyl)ethylene diphosphate; bis(2-chloro ethyl) 2-chloroethylphosphonate; diphosphates [2-chloroethyl diphosphate]; tetrakis(2-chloro ethyl) ethylenediphosphate; tris-(2-chioroethyl)-phosphate, tris-(2-chloropropyl)phosphate, tris- (2,3-dibromopropyl)-phosphate ₅ tris(l,3-dichloropropyl)phosphate tetrakis (2-chloroethyl- ethylene diphosphate and tetrakis(2-chloro ethyl) ethyleneoxyethylenediphosphate. When used as a flame retardant, the halogenated phosphate ester will comprise 0.5 to 10 percent by weight of the final foam.

Dehydratable flame retardants, such as alkali silicates, zeolites or other hydrated phosphates, borosilicates or borates, alumina hydroxides, cyanuric acid derivatives, powdered melamine, graphites, mica, vermiculites, perlites, aluminohydrocalcite, hydromagnesite, thaumasite and wermlandite. AI2O3H2O, and Alumina trihydrate, may also be used.

The dehydratable flame retardant is generally added to the polyurethane dispersion in an amount of from 5 to 120 parts per 100 parts dispersion solids of the final Compound. Preferably the flame retardant is added in an amount from 20 to 100 parts per 100 parts dispersion solids of the final Compound. More preferably the flame retardant is added in an amount from 50 to 80 parts per 100 parts dispersion solids of the final Compound.

The products that result from the methods disclosed herein typically comprise 0.1- 99% PUD based on the weight of the pre-dried mixture. Preferably, the products are comprised of 60-99% PUD based on the weight of the pre-dried mixture. Still more preferably, the products are comprised of 70-95% PUD based on the weight of the pre-dried mixture.

In the synthetic leathers, anticorrosion coatings, dried PUD films and methods of disclosed herein, the PUD has a solid content of at least 25% by weight. In one

embodiment, the PUD has a solid content that is 25-65 % by weight. More preferably the solid content of the PUD is at least 30% or more preferably at least 35% by weight. More preferably still, the solid content is at least 40% or 45%. Antioxidants are known in the art and include polymeric hindered phenol resins.

In another embodiment of any of the previously described aspects and/or embodiments, the mixture further comprises at least one additive that is a flame retardant, a pigment, a flowing additive, handfeel additive, antioxidant, anti-UV additive, or combinations thereof. Typically, these additives comprise 0.01 to 10% by weight of the solid content. More preferably, these additives comprise 0.1-8% by weight (still more preferably, 2-5%) of the solid content.

In another embodiment, the methods for producing the nanoparticle containing PUDs comprise the following:

the polyurethane prepolymer comprises a liquid isocyanate resin and two polyols; the second mixture is made by 1) combining the prepolymer with a mixture comprising a surfactant, wherein said mixture is made by combining at least one surfactant and at least one nanoparticle, and then 2) adding water and the chain extender

In a preferred embodiment, the nanoparticle is CaC0 ₃ . More preferably, the nanoparticles of CaC0 ₃ is surface modified with stearic acid.

In a preferred embodiment of any of the previously disclosed methods, the liquid isocyanate resin comprises 4,4'-methyoenediphenyl diisocyanate and the two polyols in the first mixture are propyl eneglycol-propylene oxide-ethylene oxide polymer (CAS # 53637- 25-5) and a polyethylene glycol monomethyl ether based polyol.

In another preferred embodiment of any of the previously disclosed methods, in the second mixture, the surfactant is sodium dodecylbenzene sulfonate, the chain extender is amino ethyl ethanol amine, and the nanoparticle is CaC0 ₃ that was surface modified in order to increase its hydrophobicity, Si0 ₂ , or Ti0 ₂ . One particularly preferred surface modifier for the CaC0 ₃ is stearic acid. In one embodiment of any of the aforementioned methods, the solid content of the second mixture is 25-65 % by weight.

Experimental Procedures and Data

Table 1. Raw material information

Comparative Example; Syntegra 3000 PUD control sample.

Prepolymer: PU prepolymer is prepared by charging 180 g Isonate 125 M into a three-neck flask, which was heated at 45 C for melt solid MDI to liquid. 408 g Voranal 9287A, 12 g MPEG 1000 is premixed and warmed at 55 C for lh before added to flask. Increase the temperature to 80 °C, keep 80 °C for 4-5 h to reach the target NCO% of 7.1 % (NCO:OH=3.43).

PU dispersion: 524.2 g prepolymer was placed in a plastic jar. The jar was clamped and a

Cowles blade was inserted into prepolymer such that the blade is just covered by prepolymer. 71.74 g DS-4 mixture was charged into prepolymer, following this procedure, the mixture was stirred with Cowles blade at 3000 rpm, and cold DI water (5 °C) is added into the mixture slowly as the water-in-oil was converted into an oil-in-water dispersion. A solution of 92.29 g chain extender (10% AEEA in water) is slowly fed into the dispersion with random stirring. The solid content of final dispersion PUD Syntegra 3000 is 55%. Before testing, films were prepared from dispersions that were diluted to 35 % solids. The diluted dispersions were poured into metal molds and allowed to dry for 14 days at room temperature, the thickness of the resulting dry film was about 1 mm. Testing was performed in accordance with ASTM D-412.

Example 1 ;

Prepolymer: 180 g Isonate 125 M (solid) was charged into a three-neck flask, and then heated to 45 °C in order to melt the MDI. A separate flask was charged with 408 g Voranal 9287 A and 12 g MPEG 1000, heated at 55 °C for lh and then this mixture was added to the melted MDI. The reaction temperature was increased 80 °C and then maintained for 4-5 h in order to reach the target NCO%=7.1%.

PU/NPs dispersion: 2 g nano CaC0 ₃ was added to 71.74 g DS-4 surfactant and then stirred at 3000 rpm for 5 min. A fine mixture was generated. 522.2 g prepolymer was placed in a plastic jar. The jar was secured and a Cowles blade was inserted into prepolymer such that the blade was just covered by prepolymer. The DS-4/nano CaC0 ₃ mixture was added to the prepolymer and the resulting mixture was stirred with the Cowles blade at 3000 rpm. Cold DI water (5 °C) was slowly added into the mixture. As a result, the water- in-oil dispersion was converted into an oil-in-water dispersion. A solution of 93 g chain extender (10% AEEA in water) was slowly fed into the dispersion with random stirring. The solid content of the final dispersion was 55%, with a nanoparticle (NP) content of 0.36% in solid. The sample was then dried and tested as described above for the control example. Example 2: Sample 2 Prepolymer: 180 g Isonate 125 M (solid) was charged into a three-neck flask, and then heated to 45 °C in order to melt the MDI. A separate flask was charged with 408 g Voranal 9287A and 12 g MPEG 1000, heated at 55 °C for lh and then this mixture was added to the melted MDI. The reaction temperature was increased 80 °C and then maintained for 4-5 h, until the target NCO % was reached.

PU/NPs dispersion: 35.9 nano CaC0 ₃ was added to 71.74 g DS-4 surfactant and then stirred at 3000 rpm for 5 min. 488.3 g prepolymer was placed in a plastic jar. The jar was secured and a Cowles blade was inserted into prepolymer such that the blade was just covered by prepolymer. The DS-4/nano CaC0 ₃ mixture was added to the prepolymer and the resulting mixture was stirred with the Cowles blade at 3000 rpm. Cold DI water (5 °C) was slowly added into the mixture. As a result, the water-in-oil dispersion was converted into an oil-in-water dispersion. A solution of 93 g chain extender (10% AEEA in water) was slowly fed into the dispersion with random stirring. The solid content of the final dispersion was 55%, with a nanoparticle (NP) content of 6.5% in solid. The sample was then dried and tested as described above for the control example.

Example 3 :

Prepolymer: 180 g Isonate 125 M (solid) was charged into a three-neck flask, and then heated to 45 °C in order to melt the MDI. A separate flask was charged with 408 g Voranal 9287A and 12 g MPEG 1000, heated at 55 °C for lh and then this mixture was added to the melted MDI. The reaction temperature was increased 80 °C and then maintained for 4-5 h until the target NCO % was reached.

PU/NPs dispersion: 1 .8 g nano CaC0 ₃ nano CaC0 ₃ was added to 71.74 g DS-4 surfactant and then stirred at 3000 rpm for 5 min. 522.2 g prepolymer was placed in a plastic jar. The jar was secured and a Cowles blade was inserted into prepolymer such that the blade was just covered by prepolymer. The DS-4/nano CaC0 ₃ mixture was added to the prepolymer and the resulting mixture was stirred with the Cowles blade at 3000 rpm. Cold DI water (5 °C) was slowly added into the mixture. As a result, the water-in-oil dispersion was converted into an oil-in-water dispersion. A solution of 93 g chain extender (10% AEEA in water) was slowly fed into the dispersion with random stirring. The solid content of the final dispersion was 55%, with a nanoparticle (NP) content of 3.6 % in solid. The sample was then dried and tested as described above for the control example.

Table 2 shows the mechanical properties of PU/NPs dispersion, after adding NPs into PU matrix, both tensile strength and elongation have been improved.

Table 2 Mechanical properties of the dried PU NP film

The measuring of the tensile strength and the elongation was performed in accordance with ASTM D-412.

As shown in Table 2, adding the surfactant stabilized CaC0 ₃ increases the tensile strength and the percent elongation of the samples. Adding just 0.36 % by weight of the surfactant stabilized CaC0 ₃ to the control sample increased the tensile strength by 35.7% and the elongation by 20.8%, while adding 3.6 % by weight of the surfactant stabilized CaCC-3 to the control sample increased the tensile strength by 58.6 % and the elongation by 32.5 %. And adding 6.5 % by weight of the surfactant stabilized CaC0 ₃ to the control sample increased the tensile strength by 53.9 % and the elongation by 22.2 %. Clearly, the surfactant stabilized CaC0 ₃ significantly improves the tensile strength and elongation of the samples.

Thus, in one embodiment, the material has a tensile strength that is at least 10% higher than a corresponding material that does not contain a nanoparticle. More preferably, it is at least 15% higher. Still more preferably, it is at least 20% higher.

In another embodiment, the material has a elongation that is at least 10% higher than a corresponding material that does not contain a nanoparticle. More preferably, it is at least 15% higher. Still more preferably, it is at least 20% higher.

In another embodiment, the material has a tensile strength that is at least 20% higher than a corresponding material that does not contain a nanoparticle; and/or

the material has a elongation that is at least 20% higher than a corresponding material that does not contain a nanoparticle.