GB2313128A - Stain resistant polyurethanes - Google Patents

Abstract

Stain-resistant polyurethanes are provided which are reaction products of organic isocyanates and hydrophobic compounds having at least two isocyanate-reactive hydrogens, long-chain hydrocarbons and mixtures thereof, optionally with other ingredients. The polyurethanes are hydrophobic in nature and are useful for various commercial applications. An added feature of the present invention is that the stain resistant polyurethanes can be tailored to a desired hardness.

Description

STAIN RESISTANT POLYURETHANES The present invention relates to stain resistant polyurethanes, and more particularly, to stain resistant polyurethane-based elastomers, foams and coatings.

Polyurethanes have become increasingly useful for a wide range of commercial applications. Such materials are generally characterized by outstanding mechanical properties and resistance to degradation caused by heat, oxidation, ozone attack or ultraviolet radiation. Polyurethanes are often less expensive to process than rubber and thermoplastics, thus making them highly desirable for use in industry.

While many polyurethane based compositions are known, a perceived drawback of the known materials lies in their susceptibility to staining, i.e. discoloration due to the absorption of water-soluble materials. For example, urethane-based elastomers employed as protective and/or decorative edging for furniture and countertops tend to become discolored over time when fluids such as coffee and tea, among others, have been spilled thereon. Thus, there is a need for urethane-based elastomers and foams which have outstanding mechanical properties, are resistance to degradation and are stain resistant.

According to a preferred embodiment, the present invention relates to stain resistant polyurethanes formed as the reaction product of a mixture, comprising: a) an organic isocyanate; b) a hydrophobic compound selected from the group consisting of hydrophobic compounds having at least two isocyanate reactive hydrogens, hydrophobic long chain hydrocarbons and mixtures thereof; c) optionally, when b) includes less than sufficient isocyanate reactive hydrogens to form a polyurethane, at least one second compound which is sufficiently reactive with said organic isocyanate to form a polyurethane; and d) optionally, one or more components selected from the group consisting of blowing agents, cross-linkers, catalysts, anti oxidants, W-stabilizers, flame retardants, water scavengers, plasticizers, fillers, coloring agents and mixtures thereof.

Under an alternative preferred embodiment, the invention relates to stain resistant polyurethane formed as the reaction product of a mixture comprising: a) an organic isocyanate; b) at least one hydrophobic compound capable of reacting with said organic isocyanate to form a polyurethane, said compound having at least two isocyanate reactive hydrogens; and c) optionally, one or more components selected from the group consisting of blowing agents, cross-linkers, catalysts, anti oxidants, W-stabilizers, flame retardants, water scavengers, plasticizers, fillers, coloring agents and mixtures thereof.

The stain resistant polyurethanes can be used for a number of different products including but not limited to furniture and countertop edging, appliance handles, shelving edges, and decorative moldings, for example. In general, it is contemplated that the polyurethane compositions of the present invention can be employed under any application where stain resistance is a consideration.

In addition to stain resistant urethane compositions, the present invention also relates to the formation of prepolymers which are storage stable and readily useful for the formation of various polyurethane products.

An unique aspect of the stain resistant urethane compositions of the present invention is that they may be modified such that the resulting product has the desired hardness, e.g., ranging from Shore A to Shore D upon curing.

The present invention also relates to the method of preparing both the stain resistant polyurethanes and prepolymers of the present invention.

The stain resistant polyurethanes of the present invention can be utilized to form a variety of products including but not limited to furniture and countertop edging, appliance handles, shelving edges, and decorative moldings, among others. In general, it is contemplated that the preferred urethanes of the present invention can be employed in the production of various products where stain resistance is a particular concern. As used herein, the phrase "stain resistant polyurethanes" should be understood to include both filled and unfilled polyurethane based compositions including, generally, elastomers, foams and coatings.

Hydrophobic compounds having at least two isocyanate reactive hydrogens which are considered useful, without limitation, in accordance with the teachings of the present invention include polyols having a carbon chain length of at least about C10 or higher. Preferred examples of such polyols include castor oil, castor-oil based or derived compounds, polybutadiene and saturated hydrocarbon polyols. By saturated hydrocarbon polyols, it is meant that the polyols have no double bonds in their molecular structure.

Of the aforementioned, castor oils are considered to be particularly preferred. While numerous commercially available castor oil products are useful in accordance with the teachings of the present invention, one known as DB Oil which is available from Cas Chem, Inc., of Bayonne, NJ, has been found to be particularly useful. In this regard, it has been observed that castor oil not only appears to enhance the hydrophobicity of the polyurethane compositions, i.e. resistance to water soluble staining materials such as coffee and tea, for example, but also enhances the fire retardancy characteristics of the resulting product due to char formation caused by the relatively long hydrocarbon chain length.

Under certain applications, the hydrophobic compound employed optionally or alternatively will include or employ compounds which do not have at least two isocyanate-reactive hydrogens, such compounds being referred to herein as long chain hydrocarbons. Examples of such long chain hydrocarbons include, for example, and without intending to be limiting, paraffins, olefins, vegetable and animal oils and modifications of such materials. Particularly useful of the so-called long chain hydrocarbons are hydrocarbon oils and mono-functional long chain hydrocarbon compounds such as alcohols, and/or fatty (long chain hydrocarbon) acids and fine powders.

By long chain hydrocarbons, it is meant that the hydrocarbons will have a carbon chain length of at least C10, more preferably of at least C12, still more preferably at least C16, and still more preferably, will have a carbon chain length of C18 or greater. In general, the longer the hydrocarbon chain length, the more hydrophobic in nature the hydrocarbon will be.

It should be noted that the amount of hydrophobic compound employed will depend in large part on the desired application for the end product. For example, while high quantities of castor oil will generally give rise to products having the best stain resistant characteristics, the resulting polyurethane-based product may be too soft for certain applications. By the same token, dilution of the castor oil or other such hydrophobic compound with less hydrophobic polyols, chain extenders, crosslinkers and other additives will give rise to products which are typically less stain resistant. Thus, the amount of hydrophobic compound employed in the stain-resistant polyurethane composition will be determinative upon a large number of factors, including the end use of the product. At a minimum, the preferred stain resistant polyurethanes of the present invention will generally include at least about 10.0 weight percent of a hydrophobic compound based on the total weight of composition prior to reaction with the organic isocyanate.

In addition to the hydrophobic compound, the polyurethane-based compositions of the present invention can optionally employ one or more conventional additive components at art-disclosed levels selected from the group consisting of chain extenders, crosslinkers, catalysts, anti-oxidants, W-stabilizers, flame retardants, water scavengers, fillers, coloring agents and mixtures thereof.

Suitable examples of chain extenders useful in the stain resistant urethanes of the present invention include polyoxyalkylene polyether polyols which are the polymerization product of an alkylene oxide with a polyhydric alcohol. Suitable polyhydric alcohols in-clude those disclosed above for use in the preparation of the hydroxy-terminated polyesters. Any suitable alkylene oxide and mixtures thereof may be used such as ethylene oxide, propylene oxide, butylene oxide, amylene oxide, and mixtures of these oxides, preferably propylene oxide. Polyoxy- propylene polyether polyols are more hydrophobic than their ethylene oxide counterparts. The polyalkylene polyether polyols may be prepared from other start-ing materials such as tetrahydrofuran and alkylene ox-ide-tetrahydrouran mixtures; epihalohydrins such as epichlorohydrin; as well as aralkylene oxides such as styrene oxide. The polyalkylene polyether polyols may have either primary or secondary hydroxyl groups. Included among the polyether polyols are polyoxyethylene glycol, polyoxypropylene glycol, polyoxybutylene glycol, polytetramethylene glycol, block copolymers, for example, combinations of polyoxypropylene and polyoxyethylene glycols, poly-1,2-oxybutylene and polyoxyethylene glycols, poly-1,4 tetramethylene and polyoxyethylene glycols, and copolymer glycols prepared from blends or addition of two or more alkylene oxides. The polyalkylene polyether polyols may be prepared by any known process such as, for example, the process disclosed in the Encyclopedia of Chemical Technology, Vol. 7, pp. 257-262, pub-lished by Interscience Publishers, Inc. (1951) or in U.S. Pat. No. 1,922,459; all of which are expressly incorporated herein by reference. Extensive lists of suitable polyol may be found in columns 2 and 3 of U.S.

Pat. No. 3,652,639; columns 2-6 of U.S. Pat. No. 4,421,872; and columns 4-6 of U.S. Pat. No. 4,310,632, these three patents being hereby incorporated by reference. The polyether polyols employed will generally have preferred molecular weights from 500 to 10,000, more preferably from 750 to 8000, and still more preferably from 1000 to 6000.

While polyester polyols are generally less preferred than polyether polyols in that they tend to be less soluble than polyether polyols, polyester polyols may also be employed. Suitable hydroxy-terminated polyesters include those obtained, for example, from polycarboxylic acids and polyhydric alcohols. A suitable polycarboxylic acid may be used such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, brassylic acid, thapsic acid, maleic acid, fumaric acid, glutaconic acid, a-hydromuconic acid, B-hydromuconic acid, a-butyl-a-ethylglutaric acid, a,B-diethylsuccinic acid, isophtalic acid, therphthalic acid, phthalic acid, hemimellitic acid, and 1,4-cyclohexanedicarboxylic acid. Mixtures may also be employed.

A suitable polyhydric alcohol may be used such as ethylene glycol, propylene glycol, trimethylene glycol, 1,2-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 2-methyl-1,3propanediol, hydroquinone, resorcinol glycerol, glycerine, l,l,l-trimethyIol-propane, l,l,l-trimethylolethane, 1,2,6-hexanetriol, a-methyl glucoside, sucrose, and sorbitol. Again, mixtures of such alcohols may be employed. Also included within the term "polyhydric alcohol as used herein are compounds derived from phenol such as 2,2-bis(4-hydroxyphenyl)-propane, commonly known as Bisphe-nol A. The polyester polyols, if employed, will preferably have molecular weights from 500 to 10,000, more preferably from 750 to 8000, and still more preferably from 1000 to 6000.

Preferred chain extenders will have molecular weights of from 50 to 400 generally and preferably from 60 to 300. In order to obtain the desired hardness of the polyurethanes, the amount of hydrophobic component having at least two isocyanate reactive hydrogens to chain extenders can be varied within a relatively wide molecular ratio, the hardness typically increasing with increasing content of chain extenders. For example, less rigid polyurethanes (having a Shore A hardness of less than 95, preferably from 75 to 85 after curing), will generally have molar ratios of hydrophobic component to chain extenders of from 10:1 to 20:1, preferably from 8:1 to 15:1. For more rigid polyurethanes, (for example, those having a Shore D hardness of more than 50, preferably 60 to 80 Shore D, after curing) the molar ratios of hydrophobic component to chain extenders are from 2:1 to 3:1, preferably 4:1 to 5:1.

Suitable examples of cross-linkers useful in accordance with the practice of the present invention include, without limitation, the alkylene oxide addition products of trimethylolpropane, glycer-ine, sucrose, sorbitol, propylene glycol, dipropylene glycol, pentaerythritol, and 2,2-bis (4 -hydroxyphenyl) -propane and blends thereof having equivalent weights of from 31-340.

Catalysts may also be employed in accordance with the teachings of the present invention. The catalyst generally accelerate the reaction of the active hydrogen containing compounds (if present) with the organic polyisocyanates. Examples of useful catalysts include organic metal compounds, preferably organic tin compounds such as tin (II) salts of organic carboxylic acids, e.g., tin(II) acetate, tin(II) octoate, tin(II) ethylhexoate and tin(II) laurate, as well as the dialkyline(IV) salts of organic carboxylic acids, e.g., dibutyltin diacetate, dibutyltin maleate and dioctylin diacetate. Specific examples of organic tin compounds which are useful include, without limitation, dibutyltin dilaureate, dibutyltin sulfide and tin mercaptans, among others. Other organic metal compounds which are considered useful include zinc compounds such as zinc octoate with bismuth compounds. Organometallic compounds useful as catalysts are generally disclosed in U.S. Pat. No. 2,846,408, herein incorporated by reference. The organic metal compounds are used alone or preferably in combination with strong basic amines.

Examples include amidines such as 2,3-diethyl-3,4,5,6-tetra- hydropyrimidine, tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, N-methylmorpholine, N-ethylmorpholine, N-cyclohexylmorpholine, N,N,N, ',N' -tetramethyl- ethylenediamine, N,N,N' ,N' -tetramethylbutanediamine, pentamethyldiethylentriamine, tetramethyldiaminoethyl ester bis(dimethylaminopropyl) urea, dimethylpiperazine, 1,2-dimethylimidazle, 1-aza-bicyclo[3.3.03octane and preferably 1,4-diazabicyclo [2.2.2]octane, 1,8 diazabicyclo 5,4,0 undecene 7 and alkanolamine compounds such as triethanolamine, triisopropanolamine, N-methyland N-ethyldiethanolamine and dimethylethanolamine Suitable catalysts also include tris(dialkylamino)-s-hexahydrotriazines, especially tris (N,N-dimethylaminopropyl) -s-hexahydro- triazine, tetraalkylammonium hydroxides such as tetramethylammonium dydroxide, alkali hydroxides such as sodium hydroxide and alkali alcoholates such as sodium methylate and potassium isopropylate as well as alkali salts of long-chain fatty acids with 10 to 20 carbons and optionally OH side groups. An effective amount of catalyst to promote the reaction of isocyanate groups with the polyol, or with other isocyanate groups in the case of isocyanurates, is employed. 0.001 to 5 wt percent, catalyst or catalyst combination based on the weight of polyol composition is preferred. Mixtures of amine, tin, and bismuth catalysts may be used.

Anti-oxidants may also be employed if necessary to retard the oxidation of the reacted urethane. Preferred among the numerous commercially available anti-oxidants which are considered useful are: Irganox, available from Ciba-Geigy Corp., of Greensboro, N.C.; and Cyanox, available from Cytec, Industries Inc., of Havre De Grace, MD; both are particularly useful. Mixtures of antioxidants may also be employed.

W stabilizers which can be employed include, without limitation, benzophenones, benzotriazoles, substituted acrylonitriles, phenol-nickel complexes, and mixtures thereof. Examples of commercially available W-stabilizers include Tinuvin, available from Ciba-Geigy Corp., of Greensboro, N.C., and Uvinul, available from BASF Corporation of Mt. Olive, N.J.

It may be desirable in certain applications to employ one or more flame-retardants. For example, certain flame retardants which are reactive with isocyanates which may be employed include phosphorbased products such as Fyrol 6 and Fyrol 51, available from Akzo Chemicals, Inc., of Chicago, IL; and Vircol 82 available from Mobil Chemical Co., of Norwalk, CT. Additionally, certain halogen based flame retardants, such as FR-522 and Saytex FR-1138 (which are dibromopentyl glycol based products available from AmeriBrom, Inc., and Ethyl Corporation of Richmond, VA, respectively), may be employed. Still other flame retardants which are generally non-reactive to the isocyanates may be employed. Preferred are the reactive FR series flame retardants since they are homogeneous in nature, i.e. they do not migrate to the surface of the polyurethanes. Mixtures may also be employed.

For non-foaming applications, water scavengers, otherwise referred to herein as water absorbing agents, may be employed so that any water contained in the composition is prevented from reacting with the isocyanates which in turn prevents the formation of C02 and this limits or precludes foaming. Molecular sieves which are generally silica based have proven useful in this regard. Additionally, Zolidine, which is a liquid oxazolidine available from Angus Chemicals, Inc. of Buffalo Grove, IL, is contemplated as being useful.

For applications wherein the stain resistant polyurethanes of the present invention are foams, blowing agents are typically required. Suitable blowing agents are those of the reactive type such as water, formic acid or tertiary alcohols; physically active blowing agents having a boiling point below 28 degrees C.

and which vaporize at or below the temperature of the foaming mass comprising chlorofluorocarbons having at least one hydrogen (soft CFCs) and volatile hydrocarbons, or mixtures thereof. Soft CFC's useful herein are those having an ozone depletion potential of less than 0.2 including 1,1,1 trichloroethane, 1,1,1,2-tetraflouoroethane, HCFC-14lb, HCFC-22, HCFC-123, and HCFC-142b.

Volatile hydrocarbons include butane, pentane, hexane, heptane, cyclopentane, cyclohexane, pentene, and heptene.

A surface-active substance is generally necessary for production of high grade polyurethane foam according to the present invention, since in the absence of same, the foams may collapse.

Examples of surface active substances include compounds that support the homogenization of the starting materials and are optionally also suitable for regulating the cell structure. An extensive list of surface-active substances useful in accordance with the teachings of the present invention are disclosed in U.S.

Patent No. 5,045,885 to Sampara et al., whIch is hereby expressly incorporated by reference.

Other conventional additives including, but not limited to, plasticizers, reactive and non-reactive silicone oils, fillers and coloring agents including dyes and pigments may also be employed, at conventional or art-disclosed levels. Included in the class of additive materials generally referred to herein as fillers are fibrous and particulate materials, non-polar polymeric materials and inorganic anti-block agents. Examples of such materials include glass and carbon fibers, silicas, calcium carbonate, clay, mica, talc, carbon black, particulate graphite and metallic flakes, among others.

To gain a further understanding of the various optional components which can be employed, reference can be made to various technical publications including, for example, the article by J.H. Saunders and K.C. Frisch, High Polymers, Volume XVI, Poly urethane, Parts 1 and 2 (Interscience Publishers 1962 and 1964), Kunstostoff-Handbuch, Volume 7, Polyurethane 1st and 2nd Editions (Carl Hanser Verlag, 1966 and 1994) or DE-A 29 01 774, which are hereby expressly incorporated by preference.

As alluded to previously, the hydrophobic components of the present invention are particularly useful when blended with certain isocyanate compounds. Among the numerous isocyanates, otherwise referred to herein as organic isocyanates, which are considered useful are those including aromatic, aliphatic, and cycloaliphatic polyisocyanates and combinations thereof. Examples of such isocyanates may found at columns 8 and 9 of U.S. Pat.

No. 4,690,956, herein incorporated by reference. Representative polyisocyanates are the diisocyanates such as m-phenylene diisocyanate, 2,4-toluene diisocyanate, 2, 6-toluene diisocyanate, mixtures of 2,4- and 2,6-toluene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, cyclohexane-1,4 diisocyanate, hexahydrotoluene diisocyanate (and isomers), naphthalene-1,5-diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, 4,4' -diphenylmethane diisocyanate, 4,4, -biphenylene diisocyanate, 3,3' -dimethoxy-4,4' -biphenyl diisocyanate, 3,3'-diimethyl-4,4'biphenyl diisocyanate and 3,3' -dimethyldiphenylmethane-4 ,4' - diisocyanate; the triisocyanates such as 4,4',4"-triphenylmethane triisocyanate, and toluene 2,4,6-triisocyanate; and the tetraisocyanates such as 4,4'-dimethyldiphenylmethane-2,2' -5,5, -tetraiso- cyanate and polymeric polyisocyanates such as polymethylene polyphenylene polyisocyanate, and mixtures thereof.

For preparation of the stain resistant polyurethanes of the present invention, the ratio of the equivalent weight number of NCO groups of the isocyanate (a) to the sum of hydroxyl groups of component (b) is from 300:100 to 95:100, preferably 105:100 to 100:100. By equivalent weight number, it is meant the weight of an element that combines chemically with 8 grams of oxygen or its equivalent. For example, since 8 grams of oxygen combines with 1.008 grams of hydrogen, the latter is considered equivalent to 8 grams of oxygen.

Suitable methods of preparing the stain resistant polyurethanes of the present invention include adding the hydrophobic compound to a vessel and heating to approximately 1400F. Thereafter, each of the other components including one or more compounds selected from the group consisting of chain extenders, cross-linkers, catalysts, anti-oxidants, UV-stabilizers, flame retardants, plasticizers, fillers, coloring agents and mixtures thereof, excepting any water scavengers are charged to the mixing vessel and blended with the hydrophobic compound. Upon blending, the water level of the composition is typically measured to determine whether the water level is below approximately 0.03 wt.% based on the total weight of the composition. If the water is above that level, the composition is heated further under vacuum to drive off water; however, if the water level is at or below this level, a water scavenger is added to the mixture with blending. Upon thoroughly blending the components, a resinous material results.

Thereafter, the resin is blended with the organic isocyanate to form the stain resistant polyurethane of the present invention as set forth by way of non-limiting examples below.

Other conventional or art-disclosed methods may also be employed to prepare the resins and prepolymers of the present invention.

EXAMPLE 1 A stain resistant polyurethane in accordance with the teachings of the present invention was prepared by first charging 85.7 wt.% of DB oil to a clean, dry blend tank equipped with a dry air or nitrogen purge. The DB oil was heated to 1400F and thereafter 10.0 wt.% FR-522, 0.5 wt.% Tinuvin 328, 0.5 wt.% Tinuvin T765, 0.5 wt. % Irganox 245, and 0.3 wt.% Fomrez UL 28 were slowly added with mixing to the DB oil and the composition was mixed for one hour. The composition was continuously mixed until the water level was below about 0.03 wt.% at which time 2.5 wt.% of an A-3 molecular sieve was added and the composition was mixed for approximately one half hour to form the desired resin, which was liquid and had a viscosity of approximately 700 cps and a density of 1.0 g/cc or 8.2 lbs/gal. at 770F.

One hundred parts by weight of the resin were blended with 45 parts by weight of dicyclohexylmethane diisocyanate having a viscosity of approximately 30 cps and a density of 1.07 g/cc or 8.9 lbs./gal at 770FF and molded. The mold was maintained at a temperature of between about 130-1500F. As a result of blending the resin and isocyanate together and molding the same, an urethane based elastomer product which is aliphatic, light stable and sufficiently flame retardant at a thickness of 0.5 inch to attain a E=94VO rating was obtained. The resulting polyurethane product had a hardness as measured by ASTM D2240 of 75, tensile strength of 1300 PSI according to ASTM D412, elongation at break of 200 and Graves Tear according to ASTM D1004 of 90 lbs/in.

EXAMPLE 2 A second stain resistant polyurethane was prepared by charging 39.15 wt.% DB Oil to a similar blend tank and adding 17.5 wt.% dipropylene glycol with mixing. The mixture was heated to 1400F and thereafter 0.2 wt.% Fomrez UL 28, 0.5 wt.% Tinuvin 328, 0.5 wt.% Tinuvin T765, 0.5 wt. % Irganox 245 and 39.15 wt.% Pluracol 726 were added and the composition mixed until the water level was below about 0.03 wt.% at which time 2.5 wt.% of an A-3 molecular sieve were added. The resulting composition was mixed for approximately one half hour with the resulting liquid resin having with 2.5 wt.% A-3 molecular sieve being added after the water level was below a viscosity of approximately 700 cps and a density of 0.99 g/cc or 8.2 lbs/gal. at 770F.

One hundred parts by weight of the resin were then blended with 58 parts by weight of dicyclohexylmethane diisocyanate having a viscosity of approximately 30 cps and a density of 1.07 g/cc or 8.9 lbs./gal at 770F and molded. The mold was maintained at a temperature of between about 130-1500F. The resulting polyurethane product had a hardness as measured by ASTM D2240 of approximately 80-85, tensile strength of 2100 PSI according to ASTM D412, elongation at break of 230 and Graves Tear according to ASTM D1004 of 90 lbs/in.

EXAMPLE 3 A third polyurethane composition was prepared for purposes of comparing the stain resistant characteristics of a currently employed commercial product versus those provided in accordance with the teachings of the present invention. This third example was prepared by charging 89.5 parts by weight Pluracol 538 polyol commercially available from BASF Corporation to a blending tank at 1400F along with 9.0 wt.% diethylene glycol. The mixture was blended under vacuum and nitrogen purging at a temperature of between 180 to 2120F until the water level was below 0.05%.

Thereafter, the temperature was adjusted to between 120 to 1400F and 0.5 wt.% of Tinuvin 328 was added with the mixing. The mixture was blended for approximately 25 minutes and cooled to between 70 to 1000F at which time 0.5 wt.% Tinuvin 765 and 0.5 wt.% Fomrez UL-32 catalyst were added and mixed for one half hour. The resulting resin which was liquId had a viscosity of 775 cps and a density of 1.03 g/cc or 8.6 lbs/gal at 77of.

One hundred parts by weight of the resin were mixed with 43.5 parts by weight of polymethylene polyphenylene diisocyanate, a MDI-prepolymer, having an NCO % of 23, a viscosity of approxi mately 700 cps and a density of 1.2 g/cc or 10 lbs/gal at 770F.

The mold was maintained at a temperature of about 1300F. The resulting polyurethane product had a hardness as measured by ASTM D2240 of approximately Shore 65 A, tensile strength of 630 PSI according to ASTM D412, elongation at break of 190 and Graves Tear according to ASTM D1004 of 30 lbs/in.

To analyze for stain resistance, one sample of each of the Examples I, II and III was immersed in the same coffee solution and allowed to remain for a period of twenty four hours. Thereafter, each sample was removed and wiped lightly with a clean moist towel. Upon viewing the samples, the samples formed according to Examples I and II showed virtually no signs of staining; in contrast, the sample of Example III was clearly discolored.

As alluded to earlier, in addition to their use for preparing stain resistant polyurethanes, the hydrophobic compound of the present invention can also be employed in prepolymers. In this regard, the hydrophobic resins, such as those described in Examples I and/or II above, are blended with the isocyanates and heated at the desired temperature while mixing. The NCO content of the blend is monitored during the reaction until the target % of NCO is obtained at which time the composition is cooled to ambient, .e. room temperature. Th

Claims (36)

Claims

1. A stain resistant polyurethane which is the reaction product of a mixture, comprising: a) an organic isocyanate; b) a hydrophobic compound selected from the group consisting of hydrophobic compounds having at least two isocyanate reactive hydrogens, hydrophobic long chain hydrocarbons and mixtures thereof; c) optionally, when b) includes less than sufficient iso cyanate reactive hydrogens to form a polyurethane, at least one second compound which is sufficiently reactive with said organic isocyanate to form a polyurethane; and d) optionally, one or more components selected from the group consisting of blowing agents, cross-linkers, catalysts, anti-oxidants, UV-stabilizers, flame retar dants, water scavengers, plasticizers, fillers, coloring agents and mixtures thereof.

2. The stain resistant polyurethane of claim 1, wherein said hydrophobic compound has a carbon chain length of C10 or longer.

3. The stain resistant polyurethane of claim 1, wherein said compound having at least two isocyanate reactive hydrogens is a polyol.

4. The stain resistant polyurethane of claim 3, wherein said polyol is a castor oil.

5. The stain resistant polyurethane of claim 1, wherein compo nent b) is present in an amount of at least 10.0% by weight based on the total weight of the composition.

6. The stain resistant polyurethane of claim 1, wherein the ratio of equivalent weight number of NCO groups of component a) to the sum of hydroxyl groups of component b) is from 300:100 to 95:100.

7. The stain resistant polyurethane of claim 1, wherein said long chain hydrocarbon is selected from the group consisting of paraffins, olefins, animal oils, vegetable oils and mix tures thereof.

8. The stain resistant polyurethane of claim 1, wherein said polyurethane is elastomeric.

9. The stain resistant polyurethane of claim 1, wherein said polyurethane is a foam.

10. The stain resistant polyurethane of claim 1, wherein compo nent c) is a chain extender.

11. A stain resistant polyurethane which is the reaction product of a mixture, comprising: a) an organic isocyanate; b) at least one hydrophobic compound capable of reacting with said organic isocyanate to form a polyurethane, said compound having at least two isocyanate reactive hydro gens; and c) optionally, one or more components selected from the group consisting of blowing agents, cross-linkers, catalysts, anti-oxidants, W-stabilizers, flame retar dants, water scavengers, plasticizers, fillers, coloring agents and mixtures thereof.

12. The stain resistant polyurethane of claim 11, wherein said hydrophobic compound has a carbon chain length of C10 or longer -

13. The stain resistant polyurethane of claim 11, wherein said hydrophobic compound is a polyol.

14. The stain resistant polyurethane of claim 13, wherein said polyol is a castor oil.

15. The stain resistant polyurethane of claim 11, wherein compo nent b) is present in an amount of at least 10.0% by weight based on the total weight of the composition.

16. The stain resistant polyurethane of claim 11, wherein the ratio of equivalent weight number of NCO groups of component a) to the sum of hydroxyl groups of component b) is from 300:100 to 95:100.

17. The stain resistant polyurethane of claim 11, wherein compound b) further comprises a long chain hydrocarbon.

18. The stain resistant polyurethane of claim 17, wherein said long chain hydrocarbon is selected from the group consisting of paraffins, olefins, animal oils, vegetable oils and mix tures thereof.

19. The stain resistant polyurethane of claim 11, wherein said polyurethane is elastomeric.

20. The stain resistant polyurethane of claim 11, wherein said polyurethane is a foam.

21. A stain resistant polyurethane which is the reaction product of a mixture, comprising: a) an organic isocyanate; and b) a resinous material comprising at least one hydrophobic compound selected from the group consisting of compounds having at least two isocyanate reactive hydrogens, long chain hydrocarbons and mixtures thereof, and optionally, one or more compounds selected from the group consisting of blowing agents, cross-linkers, catalysts, anti oxidants, W-stabilizers, flame retardants, water scavengers, plasticizers, fillers, coloring agents and mixtures thereof.

22. The stain resistant polyurethane of claim 21, wherein said hydrophobic compound has a carbon chain length of C10 or longer.

23. The stain resistant polyurethane of claim 21, wherein said hydrophobic compound is a polyol.

24. The stain resistant polyurethane of claim 23, wherein said polyol is a castor oil.

25. The stain resistant polyurethane of claim 21, wherein compo nent b) is present in an amount of at least 10.0% by weight based on the total weight of the composition.

26. The stain resistant polyurethane of claim 21, wherein the ratio of equivalent weight number of NCO groups of component a) to the sum of hydroxyl groups of component b) is from 300:100 to 95:100.

27. The stain resistant polyurethane of claim 21, wherein said long chain hydrocarbon is selected from the group consisting of paraffins, olefins, animal oils, vegetable oils and mixtu res thereof.

28. The stain resistant polyurethane of claim 21, wherein the polyurethane is elastomeric.

29. The stain resistant polyurethane of claim 21, wherein said polyurethane is a foam.

30. A prepolymer useful for the production of stain resistant polyurethanes, comprising: a) a resin comprising a hydrophobic compound selected from the group consisting of compounds having at least two isocyanate reactive hydrogens, long chain hydrocarbons and mixtures thereof, and optionally, one or more compounds selected from the group consisting of blowing agents, cross-linkers, catalysts, anti-oxidants, UV-stabilizers, flame retardants, water scavengers, plasticizers, fillers, coloring agents and mixtures thereof; and b) an isocyanate blended with said resin while heating, wherein the resulting composition has the desired % NCO.

31. The prepolymer of claim 30, wherein the prepolymer has an NCO content of between approximately 1.0 to 32.0% NCO.

32. A process of making stain resistant polyurethanes comprising the steps of: a) providing a hydrophobic compound selected from the group consisting of compounds having at least two isocyanate reactive hydrogens, long chain hydrocarbons and mixtures thereof to a reaction vessel and heating; b) optionally, blending in admission with component a) one or more compounds selected from the group consisting of blowing agents, cross-linkers, catalysts, anti-oxidants, W-stabilizers, flame retardants, plasticizers, fillers, coloring agents and mixtures thereof and heating the resulting blend to drive off excess water, if any; c) optionally, adding a water scavenger to the blend or admixture of a) and b) once the detected water level is below about 0.05 wt.%; and d) reacting the above admixture or blend with an organic isocyanate to form a stain resistant polyurethane.

33. A process of making a prepolymer useful for the production of stain resistant polyurethanes comprising the steps of: a) forming a resin comprising a hydrophobic compound selected from the group consisting of compounds having at least two isocyanate reactive hydrogens, long chain hydrocarbons and mixtures thereof, and optionally, one or more compounds selected from the group consisting of blowing agents, cross-linkers, catalysts, anti-oxidants, W-stabilizers, flame retardants, water scavengers, plasticizers, fillers, coloring agents and mixtures thereof; and b) blending an organic isocyanate with said resin to form a prepolymer.

34. A stain-resistant polyurethane as claimed in claim 1, 11 or 21 and substantially as hereinbefore described or exemplified.

35. A prepolymer as claimed in claim 30 and substantially as hereinbefore described or exemplified.

36. A process as claimed in claim 32 or 33 carried out substantially as hereinbefore described or exemplified.