GB2082601A - Polymerization process - Google Patents

Abstract

Polymers are prepared by free- radical polymerization of one or more ethylenically unsaturated monomers in an organic solvent in the presence of a polymeric stabilizer which is an alkylene oxide adduct of a styrene-allyl alcohol copolymer. The organic solvent can be an optionally unsaturated polyol in which case graft polymer dispersions in a polyol are produced. Alternatively, other organic solvents can be used and finely divided polymeric solids obtained which may subsequently be dispersed in a polyol. The resulting dispersions in either case may be used in the manufacture of polyurethane foams.

Description

SPECIFICATION Process for the preparation of polymers and polymer dispersions The present invention relates to the preparation of polymers by polymerizing one or more ethylenically unsaturated monomers in the presence of a free-radical initiator. In one embodiment it relates to the preparation of finely-divided polymeric solids, particularly those having particlesizesfrom 0.1 to 10 microns.

In another embodiment it relates to the preparation of stable graft polymer dispersions of low viscosity at temperatures below 100 C and containing a polyol. The polyol-containing dispersions and dispersions of the polymeric solids in polyols are useful in the preparation of polyurethane foams.

The prior art, as evidenced by U.S. Patents Nos. 3,652,659,3,875,258, 3,950,317, 3,931,092 and U.S.

Reissue Patents Nos. 28,715 and 29,014, teaches the preparation of graft polymer dispersions which are useful in the preparation of polyurethanes by the polymerization of ethylenically unsaturated monomers.

These patents disclose various methods of preparing graft polymer dispersions generally in the presence of polyols. German Published Patent Application 2,756,601 discloses the use of a stabilizer which consists of a polymer of an ethylenically unsaturated monomer or mixture of such monomers which is chemically bound to a propylene oxide polymer having a number average molecular weight of at least 800 and having a viscosity of more than 40,000 cps at 25"C.

In accordance with a first embodiment of the present invention, a process for the preparation of a finely divided solid polymer comprises polymerizing an ethylenically unsaturated monomer or mixture of monomers in the presence of a free-radical initiator and an organic solvent and is characterised in that the polymerization is conducted in the presence in addition of an effective amount of a preformed polymeric stabilizer. The preferred preformed polymeric stabilizers are alkylene oxide adducts of copolymers of styrene and allyl alcohol.

The invention also includes the polymer solids, e.g. of 0.1 to 10 micron size, thus produced and dispersions of them in liquid polyols. These dispersions may then be employed for the preparation of polyurethane foams.

In accordance with a second embodiment of the present invention a process for the preparation of a stable graft polymer dispersion comprises the in situ free radical polymerization of an ethylenically unsaturated monomer or mixture of monomers in the presence of a polyol and is characterised in that the polymerization is conducted in the presence in addition of an effective amount of a preformed polymeric stabilizer. The resulting dispersions have low viscosity at temperatures below 100 C and may be employed for the preparation of polyurethane foams.

The concentration of the preformed polymeric stabilizer which is employed is preferably at least 10 per cent based on the weight of the monomer(s). The preformed polymeric stabilizer is conveniently incorporated into the reaction flask in the presence of the solvent, a free-radical initiator, and the monomer or mixture of monomers.

The preformed polymeric stabilizer is preferably an alkylene oxide adduct of a styrene-allyl alcohol copolymer. The copolymer suitably contains from 15 weight per cent to 85 weight per cent styrene and has an equivalent weight of 58 to 4000. The alkoxylated stabilizer desirably has an equivalent weight of 220 to 8000 and a viscosity ranging from 2000 to 4000 centipoises at 25"C. As is well known to those skilled in the art, these copolymers may be prepared with, or in the absence of, a polymerization initiator. The copolymer is then reacted with an alkylene oxide. The alkylene oxides which may be employed include ethylene oxide, propylene oxide, butylene oxide and mixtures thereof.

Stabilizers for use in the process of the present invention have been successfully prepared by the following general procedure in which parts and percentages are by weight: 5 Parts of toluene and 5 parts of a styrene-allyl alcohol copolymer having an equivalent weight of 300 and a hydroxyl content of 5.7 per cent were charged to a reaction flask equipped with a stirrer, thermometer and water-cooled condenser. After the mixture had been heated to about 90 C to 1 OO"C, 44 parts of 45 per cent KOH were added and water was azeotroped off. To the reaction mixture was added 2340 parts of propylene oxide, maintaining the temperature of the reaction mixture between 90 and 100"C. After addition of the propylene oxide was complete, the reaction mixture was refluxed for 4 to 5 hours.The product was then treated with adsorbent to remove the KOH and stripped for 1 hour at 105"C at less than 10 millimeters Hg pressure.

The weight ratio of monomer to preformed polymeric stabilizer which is employed may vary from 10:1 to 1:1. The polymerization of the ethylenically unsaturated monomer or monomers may be carried out at a temperature between 50"C and 170"C, preferably between 80"C and 100"C. The preformed polymeric stabilizer is conveniently incorporated in the solvent, e.g. polyol, that is initially added to the reaction, upon which the monomer and catalyst are added to the reaction vessel. This polyol may or may not contain unsaturation within the molecule but preferably contains at least 0.3 mole of unsaturation per mole of polyol.

The advantages of employing the process of the present invention are that the finely-divided solid polymers may be prepared (1) at low temperatures, that is, at about 80"C, and (2) only about one-half of the free-radical initiator normally required, is required. Further advantages of the first embodiment are (3) high solids contents > 30% when dispersed in polyol have relatively low viscosities, and (4) these dispersions may be prepared employing a wide variety of polyols.

Representative ethylenically unsaturated monomers which may be employed in the present invention include butadiene, isoprene, 1,4-pentadiene, 1,5-hexadiene, 1,7-octadiene, styrene, alpha-methylstyrene, methylstyrene, 2,4-dimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexy Istyrene, benzylstyrene, and the like; substituted styrenes such as chlorostyrene, 2,5-dichlorostyrene, bromostyrene, fluorostyrene, trifluoromethylstyrene, iodostyrene, cyanostyrene, nitrostyrene, N,Ndimethylaminostyrene, acetoxylstyrene, methyl-4-vinylbenzoate, phenoxystyrene, p-vinyldiphenyl sulfide, p-vinylphenyl oxide, and the like; the acrylic and substituted acrylic monomers such as acrylonitrile, acrylic acid, methacrylic acid, methylacrylate,2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, methyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, isopropyl methacrylate, octyl methacrylate, methacrylonitrile, methyl alpha-chloroacrylate, ethyl alpha-ethoxyacrylate, methyl alpha-acetaminoacrylate, butyl acrylate,2-ethylhexyl acrylate, phenyl acrylate, phenyl methacrylate, alpha-chloroacrylonitrile, N,N-dimethylacrylamide, N,N-dibenzylacrylamide, N-butylacrylamide, methacrylyl formamide, and the like; the vinyl esters, vinyl ethers, vinyl ketones, etc., such as vinyl acetate, vinyl chloroacetate, vinyl alcohol, vinyl butyrate, isopropenyl acetate, vinyl formate, vinyl acrylate, vinyl methacrylate, vinyl methoxyacetate, vinyl benzoate, vinyl iodide, vinyltoluene, vinylnaphthalene, vinyl bromide, vinyl fluoride, vinylidene bromide, 1 -chloro-1 -fluoroethylene, vinylidene fluoride, vinyl methyl ether, vinyl ethyl ether, vinyl propyl ethers, vinyl butyl ethers, vinyl 2-ethylhexyl ether, vinyl phenyl ether, vinyl 2-methoxyethyl ether, methoxybutadiene, vinyl 2-butoxyethyl ether, 3,4-dihydro-1,2-pyran, 2-butoxy-2'-vinyloxy diethyl ether, vinyl 2-ethylmercaptoethyl ether, vinyl methyl ketone, vinyl ethyl ketone, vinyl phosphonates such as bis(betachloroethyl) vinyl-phosphonate, vinyl phenyl ketone, vinyl ethyl sulfide, vinyl ethyl sulfone, N-methyl-Nvinylacetamide, N-vinyl-pyrrolidone, vinyl imidazole, divinyl sulfide, divinyl sulfoxide, divinyl sulfone, sodium vinylsulfonate, methyl vinylsulfonate, N-vinyl pyrrole, and the like; dimethyl fumarate, dimethyl maleate, maleic acid, crotonic acid, fumaric acid, itaconic acid, monomethyl itaconate, t-butylaminoethyl methacrylate, di-methylaminoethyl methacrylate, glycidyl acrylate, allyl alcohol, glycol monoesters of itaconic acid, dichlorobutadiene, vinyl pyridine, and the like. Any of the known polymerizable monomers can be used and the compounds listed above are illustrative and not restrictive of the monomers suitable for use in this invention. Preferably, the monomer is selected from the group consisting of acrylonitrile, styrene, methyl methacrylate and mixtures thereof.

The amount of ethylenically unsaturated monomer employed in the polymerization reaction is generally from one percent to 80 percent, preferably from 30 percent to 50 percent, based on the total weight of the reaction mixture in the first embodiment, and from one percent to 50 percent, preferably from 15 percent to 40 percent, based on the total weight of the product in the second embodiment. The polymerization occurs at a temperature between about 25"C and 170"C, preferably from 80"C to 100"C.

In the first embodiment the finely-divided polymer prepared from the ethylenically unsaturated monomer or monomers may be dispersed in a polyol in a concentration ranging from 1 to 95 weight percent based on the weight of polyol, preferably from 55 to 95 weight percent.

Illustrative initiators which may be employed are the well-known free radical types of vinyl polymerization initiators, for example, the peroxides, persulfates, perborates, percarbonates, azo compounds, etc., including hydrogen peroxide, dibenzoyl peroxide, acetyl peroxide, benzoyl hydroperoxide,t-butyl hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, butyryl peroxide, diisopropyl-benzene hydroperoxide, cumene hydroperoxide, paramenthane hydroperoxide, diacetyl peroxide, di-alpha-cumyl peroxide, dipropyl peroxide, diisopropyl peroxide, isopropyl-t-butyl peroxide, butyl-t-butyl peroxide, dilauroyl peroxide, difuroyl peroxide, bis(triphenylmethyl) peroxide, bis(p-methoxybenzoyl)-peroxide, p-monomethoxybenzoyl peroxide, rubene peroxide, ascaridol, t-butyl peroxybenzoate, diethyl peroxyterephthalate, propyl hydroperoxide, isopropyl hydroperoxide, n-butyl hydroperoxide, t-butyl hydroperoxide, cyclohexyl hydroperoxide, transdecal in hydroperoxide, alpha-methylbenzyl hydroperoxide, alpha-methyl-alpha-ethyl benzyl hydroperoxide, tetralin hydroperoxide, triphenylmethyl hydroperoxide, diphenylmethyl hydroperoxide, alpha-alpha'-azo-2methyl butyronitrile, alpha,alpha'-azo-2-methyl heptonitrile, 1,1 '-azo-1-cyclohexane carbonitrile, dimethyl alpha,alpha'-azoisobutyrate, 4,4'-azo-4-cyanopentanoic acid, azobis-(iso-butyronitrile), 1 -t-amylazo-1 - cyanocyclohexane, persuccinic acid, diisopropyl peroxy dicarbonate, 2-t-butylazo-2-cyano-4-methyl pentane, and the like; a mixture of catalysts may also be used. Azobis(isobutyronitrile) and 2-t-butylazo-2-cyano-4methylpentane are the preferred catalysts.Generally, from about 0.5 percent to about 10 percent, preferably from about 1 percent to about 4 percent, by weight of catalyst based on the weight of the monomer will be employed in the process of the invention.

To be useful in the first embodiment of the present invention, the solvent employed preferably has a boiling point of from 20"C to 2500C at ambient pressure. Repesentative organic solvents which may be employed in the preparation of the polymeric solids include aliphatic, alicyclic and aromatic hydrocarbons, alcohols, esters, ketones, amides, amines, ethers, nitriles, sulfoxides and the corresponding nitro- and halo-substituted derivatives thereof. These include pentane, hexane, heptane, nonane, undecane, dodecane, petroleum ether, methanol, ethanol, isopropanol, butanol, benzyl alcohol, acetone, propanone, methylethylketone, ethylbutylketone, acetophenone, benzil, naphthalene, toluene, 1 ,2,4-trimethylbenzene, ethylacetate, isopropylacetate, butylacetate, carbon tetrachloride, chloroform, chlorobenzene, trichloroethylene, 1,1,1- trichloro-2,2,2-trifluoroethane, trifluorochloromethane, dimethylformamide, dimethylsulfoxide, tetrahydrofuran, bis(2-methoxy-ethylether), benzonitrile, 2-nitropropane, nitrobenzene and acetonitrile. Mixtures of the above solvents may also be employed. The particular solvent employed is not critical to the process of the invention.The preferred solvents are the aliphatic alcohols having from one to four carbon atoms such as methanol, ethanol, propanol, isopropanol, and the various butanols.

As previously mentioned the finely divided polymer solid produced in the first embodiment is dispersed in a liquid polyol. Representative polyols as dispersing media which may be employed in the first embodiment of the present invention are well known in the art. They are often prepared by the catalytic condensation of an alkylene oxide or mixture of alkylene oxides either simultaneously or sequentially with an organic compound having at least two active hydrogen atoms such as evidenced by U.S. Patents Nos. 1,922,459, 3,190,927 and 3,346,557.

Representative polyols include polyhydroxyl-containing polyesters, polyalkylene polyether polyols, polyhydroxy-terminated polyurethane polymers, polyhydroxyl-containing phosphorus compounds, and alkylene oxide adducts of polyhydric polythioesters, polyacetals, aliphatic polyols and thiols, ammonia, and amines including aromatic, aliphatic, and heterocyclic amines, as well as mixtures thereof. Alkylene oxide adducts of compounds which contain two or more different groups within the above-defined classes may also be used such as amino alcohols which contain an amino group and a hydroxyl group. Also, alkylene oxide adducts of compounds which contain one -SH group and one -OH group as well as those which contain an amino group and a -SH group may be used. Generally, the equivalent weight of the polyols will vary from 100 to 10,000, preferably from 1000 to 3000.

Any suitable hydroxy-terminated polyester may be used such as are obtained, for example, from polycarboxylic acids and polyhydric alcohols. Any 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, aipha-hydromuconic acid, alpha-butyl-alpha-ethylglutaric acid, alpha,beta-diethylsuccinic acid, isophthalic acid, terephthalic acid, hemimellitic acid, and 1,4-cyclohexanedicarboxylic acid.Any suitable polyhydric alcohol, including both aliphatic and aromatic, may be used such as ethylene glycol, propylene glycol, trimethylene glycol, 1 ,2-butanediol, 1 ,3-butanediol, 1 ,4-butanediol, 1 ,2-pentanediol, 1,4-pentanediol, 1 ,5-pentanediol, 1,6- hexanediol, 1,7-heptanediol, glycerol, 1,1,1 -trimethylolpropane, 1,1,1 -trimethylolethane, 1 2,6-hexanetriol, alpha-methyl glucoside, pentaerythritol, and sorbitol. Also included within the term "polyhydric alcohol" are compounds derived from phenol such as 2,2'-bis(4,4'-hydroxyphenyl)propane, commonly known as Bisphenol A.

Any suitable polyalkylene polyether polyol may be used such as the polymerization product of an alkylene oxide or of an alkylene oxide with a polyhydric alcohol. Any suitable polyhydric alcohol may be used such as those disclosed above for use in the preparation of the hydroxy-terminated polyesters. Any suitable alkylene oxide may be used such as ethylene oxide, propylene oxide, butylene oxide, amylene oxide, and mixtures of these oxides. The polyalkylene polyether polyols may be prepared from other starting materials such as tetrahydrofuran and alkylene oxide-tetrahydrofuran 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-oxybutylene and polyoxyethylene glycols, and random copolymer glycols prepared from blends of sequential 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 by Wurtz in 1859 and Encyclopedia of Chemical Technology, Vol. 7, pp. 257-262, published by Interscience Publishers, Inc.

(1951) or in U.S. Patent No. 1,922,459. Polyethers which are preferred include the alkylene oxide addition products of trimethylolpropane, glycerine, pentaerythritol, sucrose, sorbitol, propylene glycol, and 2,2'-(4,4'-hydroxyphenyl)propane and blends thereof having equivalent weights of from 100 to 5000.

Suitable polyhydric polythioethers which may be condensed with alkylene oxides include the condensation product of thiodiglycol or the reaction product of a dihydric alcohol such as is disclosed above for the preparation of the hydroxyl-containing polyesters with any other suitable thioether glycol.

The hydroxyl-containing polyester may also be a polyester amide such as is obtained by including some amine or amino alcohol in the reactants for the preparation of the polyesters. Thus, polyester amides may be obtained by condensing an amino alcohol such as ethanolamine with the polycarboxcylic acids set forth above or they may be made using the same components that make up the hydroxyl-containing polyester with only a portion of the components being a diamine such as ethylene diamine.

Polyhydroxyl-containing phosphorus compounds which may be used include those compounds disclosed in U.S. Patent No. 3,639,542. Preferred polyhydroxyl-containing phosphorus compounds are prepared from alkylene oxides and acids of phosphorus having a P205 equivalency of from about 72 percent to about 95 percent.

Suitable polyacetals which may be condensed with alkylene oxides include the reaction product of formaldehyde or other suitable aldehyde with a dihydric alcohol or an alkylene oxide such as those disclosed above.

Suitable aliphatic thiols which may be condensed with alkylene oxides include alkanethiols containing at least two -SH groups such as 1,2-ethanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, and 1,6hexanedithiol; alkene thiols such as 2-butene-1 ,4-dithiol; and alkynethiols such as 3-hexyne-1 ,6-dithiol.

Suitable amines which may be condensed with alkylene oxides include aromatic amines such as aniline, o-chloroaniline, p-aminoaniline, 1 ,5-diaminonaphthalene, methylene dianiline, the condensation products of aniline and formaldehyde, and 2,4-diaminotoluene; aliphatic amines such as methylamine, triisopropanolamine, ethylenediamine, 1,3-diaminopropane, 1,3-diaminobutane, and 1,4-diaminobutane.

Also, polyols containing ester groups can be employed in the subject invention. These polyols are prepared by the reaction of an alkylene oxide with an organic dicarboxylic acid anhydride and a compound containing reactive hydrogen atoms. A more comprehensive discussion of these polyols and their method of preparation can be found in U.S. Patents Nos. 3,585,185; 3,639,541 and 3,639,542.

The polyols which may be employed in the second embodiment of the present invention are well known in the art. Both conventional polyols essentially free from ethylenic unsaturation, such as those described in U.S. Reissue Patent No. 28,715, and discussed above as suitable dispersing media for use in the first embodiment and unsaturated polyols such as those described in U.S. Patent No. 3,652,659 and Reissue Patent No. 29,014, may be employed in the second embodiment of the invention.

The unsaturated polyols which may be employed in the second embodiment of the present invention may be prepared by the reaction of any conventional polyol such as those described above with an organic compound having both ethylenic unsaturation and a hydroxyl, carboxyl, anhydride, isocyanate or epoxy group or they may be prepared by employing an organic compound having both ethylenic unsaturation and a hydroxyl, carboxyl, anhydride, or epoxy group as a reactant in the preparation of the conventional polyol.

Representative of such organic compounds include unsaturated mono-and polycarboxylic acids and anhydrides such as maleic acid and anhydride, fumaric acid, crotonic acid and anhydride, propenyl succinic anhydride, and halogenated maleic acids and anhydrides, unsaturated polyhydric alcohols such as 2-butene-1 4-diol, glycerol allyl ether, trimethylol propane allyl ether, pentaerythritol allyl ether, pentaerythritol vinyl ether, pentaerythritol diallyl ether, and 1-butene-3,4-diol, unsaturated epoxides such as 1 vinylcyclohexene-3,4-epoxide, butadiene monoxide, vinyl g lycidyl ether (1 -vinyloxy-2,3-epoxy propane), glycidyl methacrylate and 3-allyloxypropylene oxide (allyl glycidyl ether).If a polycarboxylic acid or anhydride is employed to incorporate unsaturation into the polyols, it is preferable to react the unsaturated polyol with an alkylene oxide, preferably ethylene or propylene oxide, to replace the carboxyl groups with hydroxyl groups prior to employment in the present invention. The amount of alkylene oxide employed is such as to reduce the acid number of the unsaturated polyol to about one or less.

To prepare the unsaturated polyols for use in the second embodiment of the present invention, from about 0.05 mole to about 3.0 moles, preferably from 0.30 mole to 1.50 moles, of said organic compound per mole of polyol is employed. The preparation of the unsaturated polyols employed in the present invention follows conventional prior art procedures such as disclosed in U.S. Patent No. 3,275,606 and U.S. Patent No.

3,280,077. Generally, this requires a reaction at a temperature between 0 C and 130"C. Both acidic catalysts such as Lewis acid catalysts and basic catalysts such as alkali metal hydroxides, may be used. In addition, a non-catalyzed reaction may be used employing temperatures between 50"C and 200"C.

If desired, a chain transfer agent such as 1-dodecanethiol may be employed in the second embodiment of the invention. Under some conditions, it may be desirable to add a relatively inert solvent to the polymerisation mixture in the second embodiment of the invention. Suitable solvents are those listed above in connection with the first embodiment of the invention.

The polyurethane foams of the present invention are generally prepared by the reaction of the product of the first embodiment, namely a polyol having dispersed therein the finely divided solid polymer, or the product of the second embodiment, namely the graft polymer dispersion, with an organic polyisocyanate in the presence of a blowing agent and optionally in the presence of additional polyhydroxyl-containing components, chain-extending agents, catalysts, surface-active agents, stabilizers, dyes, fillers and pigments.

Suitable processes for the preparation of cellular polyurethane plastics are disclosed in U.S. Reissue Patent 24,514togetherwith suitable machinery to be used in conjunction therewith. When water is added as the blowing agent, corresponding quantities of excess isocyanate to react with the water and produce carbon dioxide may be used. It is also possible to proceed with the preparation of the polyurethane plastics by a prepolymertechnique wherein an excess of organic polyisocyanate is reacted in a first step with the polyol-containing composition of the present invention to prepare a prepolymer having free isocyanate groups which is then reacted in a second step with water to prepare a foam. Alternately, the components may be reacted in a single working step commonly known as the "one-shot" technique of preparing polyurethanes.Furthermore, instead of water, low boiling hydrocarbons such as pentane, hexane, heptane, pentene, and heptene; azo compounds such as azohexahydrobenzodinitrile; halogenated hydrocarbons such as dichlorodifluoromethane, trichlorofluoromethane, dichlorodifluoroethane, vinylidene chloride, and methylene chloride may be used as blowing agents.

Organic polyisocyanates which may be employed include aromatic, aliphatic, and cycloaliphatic polyisocyanates and combinations thereof. Representative of these types are the diisocyanates such as m-phenylene diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, mixtures of 2,4- and 2,6tolylene diisocyanate, hexamethylene-1 ,6-diisocyanate, tetramethylene-1 ,4-diisocyanate, cyclohexane-1,4diisocyanate, hexahydrotolylene diisocyanate (and isomers), naphthylene-1,5-diisocyanate, 1- methoxyphenyl-2,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, 4,4'-biphenylene diisocyanate, 3,3'dimethoxy-4,4'-biphenyl diisocyanate, 3,3'-dimethyl-4,4'-biphenyl diisocyanate and 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate; the triisocyanates such as 4,4',4"-triphenylmethane triisocyanate, polymethylene polyphenylisocyanate and tolylene 2,4,6-triisocyanate; and the tetraisocyanates such as 4,4'-dimethyldiphenylmethane-2,2'-5,5'4etraisocyanate. Especially useful due to their availability and properties are tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate and polymethylene polyphenylisocyanate.

Crude polyisocyanate may also be used in the compositions of the present invention, such as crude toluene diisocyanate obtained by the phosgenation of a mixture of toluene diamines or crude diphenylmethane isocyanate obtained by the phosgenation of crude diphenylmethyl diamine. The preferred unreacted or crude isocyanates are disclosed in U.S. Patent No.3,215,652.

As mentioned above, the graft polymer and copolymer dispersions may be employed along with another polyhydroxyl-containing component commonly employed in the art. Any of the polyhydroxyl-containing components which are described above for use in the preparation of the graft polymer and copolymer dispersions or the graft polyols as the case may be may be employed in the preparation of the polyurethane foams of the present invention.

Chain-extending agents which may be employed in the preparation of the polyurethane foams include those compounds having at least two functional groups bearing active hydrogen atoms such as water, hydrazine, primary and secondary diamines, amino alcohols, amino acids, hydroxy acids, glycols, or mixtures thereof. A preferred group of chain-extending agents includes water and primary and secondary diamines which react more readily with the prepolymer than does water such as phenylene diamine, 1,4-cyclohexane-bis-(methylamine), ethylene diamine, diethylene triamine, N-(2-hydroxypropyl)ethylene diamine, N,N'-di(2-hydroxypropyl)ethylene diamine, piperazine, 2-methylpiperazine, and morpholine.

Any suitable catalyst may be used including tertiary amines such as, for example, triethylene diamine, N-methyl morpholine, N-ethyl morpholine, diethyl ethanolamine, N-cocomorpholine, 1-methyl-4dimethylamino ethyl piperazine, 3-methoxy-N-dimethyl propyl amine, N-dimethyl-N'-methyl isopropyl propylene diamine, N,N'-diethyl-3-diethyl amino propyl amine, dimethyl benzyl amine, and the like. Other suitable catalysts are, for example, tin compounds such as stannous chloride, tin salts of carboxylic acids, such as dibutyltin di-2-ethyl hexoate, tin alcoholates such as stannous octoate, as well as other organo metallic compounds such as are disclosed in U.S. Patent No. 2,846,408.

A surface-active agent is generally necessary for production of high grade polyurethane foam according to the present invention, since in the absence of same, the foams collapse or contain very large uneven cells.

Numerous surfactants have been found satisfactory. Nonionic surfactants are preferred. Of these, the nonionic surface-active agents prepared by the sequential addition of propylene oxide and then ethylene oxide to propylene glycol and the solid or liquid organosilicones have been found particularly desirable.

Other surface-active agents which are operative, although not preferred, include polyethylene glycol ethers of long chain alcohols, tertiary amine or alkylolamine salts of long chain alkyl acid sulfate esters, alkyl sulfonic esters, and alkyl arylsulfonic acids.

The following examples iliustrate the nature of the invention. All parts are by weight unless otherwise stated. In the examples, the physical properties of the polyurethane foam were determined by the following ASTM tests: Tensile strength D-412 Elongation D-412 Block tear D-470 Compression load D-1654 Compression set D-1395 In Examples 1-15, which illustrate the first embodiment, the composition of the stabilizers and the polyols designated by the letters A, B, etc., is as follows.

Stabilizer A is a propylene oxide adduct of a copolymer of styrene-allyl alcohol with an equivalent weight of 220 and a hydroxyl content of 7.7 percent, the stabilizer equivalent weight being 1000.

Stabilizer B is a propylene oxide adduct of a copolymer of styrene-allyl alcohol with an equivalent weight of 300 and a hydroxyl content of 5.7 percent, the stabilizer equivalent weight being 2800.

Stabilize C is a propylene oxide adduct of a copolymer of styrene-allyl alcohol with an equivalent weight of 220 and a hydroxyl content of 7.7 percent, the stabilizer equivalent weight being 2100.

Stabilizer D is a propylene oxide ethylene oxide adduct of a copolymer of styrene-allyl alcohol with an equivalent weight of 220 and a hydroxyl content of 7.7 percent, the ratio of propylene oxide to ethylene oxide is 2 to 1 and the stabilizer equivalent weight is 1200.

Polyol A is a propylene oxide adduct of glycerine having an equivalent weight of 1000.

Polyol B is an ethylene oxide propylene oxide adduct of glycerine having an equivalent weight of about 1000 and containing 9 percent ethylene oxide.

Polyol C is an ethylene oxide propylene oxide adduct of glycerine having an equivalent weight of 830 and containing 6 percent ethylene oxide.

Example 1 A one-liter, four-necked flask fitted with a stirrer, water cooled condenser, nitrogen inlet and thermowell was charged with 170 parts isopropanol, 30 parts Stabilizer A, 100 parts styrene, 100 parts of acrylonitrile, and 2.0 parts of 2,2'-azobisisobutyronitrile. The reaction mixture was heated to 80"C and allowed to react for three hours. At the end of the reaction period 270 parts of Polyol A was added to the isopropanol dispersion.

Volatiles of isopropanol and unreacted monomer were removed at 1000C and less than 1 millimeter of mercury pressure. The product collected had a Brookfield viscosity of 3080 centipoises at 25"C.

Examples 2-12 Examples 2-12 were prepared in a manner similar to that of Example 1 with the exception that other stabilizers and polyols were employed.

TABLE I Stabilizerl Isopropanoll Styrenel Acrylonitrilel Viscosity Example parts parts parts parts cps @ 25"C 2 A/50 300 85 85 2985 3 B/50 300 85 85 3155 4 C/50 300 85 85 2910 5 -- 300 85 85 Coagulated 6 */50 300 85 85 Coagulated.

7 A/50 250 85 85 2950 8 A/25 175 100 100 3350 9 A/40 170 100 100 3080 10 A/30 170 100 100 Solid 11 D/53 304 80.5 80.5 2665 12 D/56 302 86 86 Solid *Polyol B was employed in Example 6 instead of any stabilizer.

Examples 10 and 12 did not have Polyol A added to the reaction mixture prior to removal of the volatiles.

Examples 13-15 Using a one-quart capacity cylindrical container equipped with the Lightning Model V-7 mixer fitted with a shrouded blade, the indicated amounts of polyol, water, catalyst and silicone surfactant was added to the container. The mixture was stirred for about 30 seconds, allowed to set for about 15 seconds and stirring was resumed. After about 60 seconds elapsed time, the polyisocyanate was added to the container and the resulting mixture was stirred for about 4 to 5 seconds. The contents of the container were then immediately poured into cardboard cake boxes and the foams were allowed to rise therein. After foam rise was completed, the resulting foams were oven cured for about 5-8 minutes. The following table, Table II, sets forth the ingredients and amounts that were used to prepare the foams as well as the physical properties of the foams. Good physical properties of the foams were obtained.

TABLE II Example 13 14 15 Ingredients Dispersion of Ex. 4, parts 300 0 0 Dispersion of Ex. 7, parts 0 300 0 Duspersion of Ex. 2, parts 0 0 231.4 Polyol A, parts 0 0 68.6 Distilled water, parts 9.0 -- - Triethylenediamine, parts 0.2 -- - Silicone surfactant, parts 3.0 -- - Dibutyltin dilaurate, parts 0.4 0.4 0.6 TDI, 80/20 (105 index), parts 106.9 109.0 111.3 Physical Properties Rise time, sec. 102 96 90 Density, g/cc 0.0319 0.0306 0.0309 Tensile strength, kg/cm2 1.19 1.07 1.11 Elongation, % 60 50 63 Block tear, pi. 0.7 0.5 0.7 CLD, psi.

50% defl. 1.78 1.92 1.48 CLD, psi. (humid aged) 50% defl. 1.25 1.53 1.12 Compression set, % 50% 5.1 6.4 4.4 90% 7.8 6.9 6.4 Compression set, % (humid aged) 50% 6.5 6.7 3.9 90% 11.8 10.2 9.3 Airflow, cfm. 1.62 0.36 0.46 In Examples 16-27, which illustrate the second embodiment, the composition of the stabilizers and the polyols designated by the letters A, B, etc., is as follows: Polyol A - is a propylene oxide ethylene oxide adduct of a glycerine propylene glycol mixture, equivalent weight 1700, containing 15 weight percent ethylene oxide and 0.3 moles of unsaturation per mole of polyol.

Polyol B - is a propylene oxide ethylene oxide adduct of glycerine containing 16.5 weight percent ethylene oxide with an equivalent weight of 1600.

Polyol C - is polyol A containing 8 weight percent acrylonitrile and 12 weight percent styrene as a graft copolymer dispersion.

Stabilizer D - is a propylene oxide adduct of a copolymer of styrene-allyl alcohol with an equivalent weight of 300 and a hydroxyl content of 5.7 percent, the stabilizer equivalent weight being 2800.

Stabilizer E - is a propylene oxide adduct of a copolymer of styrene-allyl alcohol with an equivalent weight of 220 and a hydroxyl content of 7.7 percent, the stabilizer equivalent weight being 2100.

Example 16 Into a one liter, four neck flask fitted with a stirrer, thermometer, nitrogen inlet, water cooled condenser and inlettube was charged 300 parts of Polyol A, 20 parts of Stabilizer D, 10 parts of styrene, 10 parts of acrylonitrile, 0.3 part of 2,2'-azobisisobutyronitrile, and 0.4 part of dodecanethiol. The mixture was heated to 80"C. After 20 minutes, the addition of a monomer consisting of 50 parts of styrene and 50 parts of acrylonitrile was begun simultaneously with a stream of 160 parts of Polyol A, 0.9 part of 2,2'azobisisobutyronitrile and 0.9 part of dodecanethiol was begun. The monomer addition time was 65 minutes. The polyol addition time was 70 minutes. The mixture temperature was then raised to 900C for 60 minutes.The resulting product was vacuum stripped at 110"C and less than 1 millimeter Hg pressure. The product had a Brookfield viscosity at 25"C of 2830 cps.

Examples 17-24 Examples 17-24 were prepared in a manner similar to the process employed in Example 16. Polyol A was employed at a level of 460 parts. The other variables are listed in Table III below with the resulting Brookfield viscosities of the products prepared.

TABLE III Reaction Reaction Monomer Polyol Isopropanol, Mercaptan, Stabilizer/ Temperature Time Feed Feed Viscosity Example Parts Parts Parts 0 C (min.) (min.) (min.) cps, 25 C 17 --- 1.5 D/20 90 60 64 70 7,830 18 --- 1.5 D/20 100 45 60 65 2,160 19 39 1.5 D/20 80 180 --- --- 2,050 20 --- 1.5 E/20 90 60 65 70 2,430 21 39 1.5 E/20 90 60 65 70 1,980 22 39 --- E/20 90 60 65 70 1,970 23 --- 1.5 --- 90 30 64 70 13,260 24 --- --- E/20 90 60 65 70 33,080 Examples 25-27 Using a one-quart capacity cylindrical containing equipped with the Lightning Model V-7 mixer fitted with a shrouded blade, the indicated amounts of polyol, water, catalyst and silicone surfactant was added to the container. The mixture was stirred for about 30 seconds, allowed to set for about 15 seconds and stirring was resumed.After about 60 seconds elapsed time, the polyisocyanate was added to the container and the resulting mixture was stirred for about 4 to 5 seconds. The contents of the container were then immediately poured into cardboard cake boxes and the foams were allowed to rise therein. After foam rise was completed, the resulting foams were oven cured for about 5-8 minutes. The following table, Table IV, sets forth the ingredients and amounts that were used to prepare the foams as well as the physical properties of the foams.

TABLE IV 25 26 27 Composition of Ex. 17, parts 300 0 0 Composition of Ex. 18, parts 0 300 0 Polyol C, parts 0 0 300 Distilled water, parts 8.1 8.1 8.1 Triethylenediamine, parts 0.7 0.7 0.7 Silicone surfactant, parts 4.0 4.0 4.0 Dibutyltin dilaurate, parts 0.02 0.02 0.02 TDl-PAPl 80/20(105 index), parts 102 102 102 Physical Properties Rise time, sec. 120 120 100 Density, g/cc 0.0327 0.0320 0.0328 Tensile strength, kg/cm2 1.68 1.63 1.55 Elongation, % 160 170 159 Block tear, pi. 2.6 1.8 2.1 CLD, psi.

50% defl. 0.55 0.54 0.44 CLD, psi. (humid aged) 50% defl. 0.42 0.41 0.35 Compression set, % 50% 8.0 9.2 14.8 90% 6.4 7.1 92.1 Compression set, % (humid aged) 50% 12.2 20.5 25.3 90% 21.0 24.6 75.4 Airflow, cfm. 1.54 0.53 0.60

Claims (17)

1. A process for the preparation of a finely divided solid polymer comprising polymerizing an ethylenically unsaturated monomer or mixture of monomers in the presence of a free-radical initiator and an organic solvent, wherein the polymerization is conducted in the presence in addition of an effective amount of a preformed polymeric stabilizer.

2. A process for the preparation of a dispersion of a graft polymer in a polyol comprising the in situ polymerization of an ethylenically unsaturated monomer or mixture of monomers in a polyol in the presence of a free-radical initiator, wherein the polymerization is conducted in the presence of an effective amount of a preformed polymeric stabilizer.

3. A process as claimed in claim 1 or 2 wherein the monomer or monomer mixture is selected from acrylonitrile, styrene and methyl methacrylate.

4. A process as claimed in any of claims 1 to 3 wherein the free-radical initiator is azobis(isobutyronitrile).

5. A process as claimed in any of claims 1 to 3 wherein the free-radical initiator is 2-t-butylazo-2-cyano-4methylpentane.

6. A process as claimed in any of claims 1 to 5 wherein the preformed polymeric stabilizer is an alkylene oxide adduct of a copolymer of styrene-allyl alcohol and has an equivalent weight of 220 to 8000.

7. A process as claimed in claim 6 wherein the styrene-ailyl alcohol copolymer contains from 15 to 85 weight percent styrene, and has an equivalent weight of from 58 to 4000.

8. A process as claimed in claim 6 or 7 wherein the alkylene oxide is selected from ethylene oxide, propylene oxide and butylene oxide.

9. A process as claimed in any of claims 1 to 8 wherein the concentration of ethylenically unsaturated monomer is from 1 to 50 weight percent based on the total weight of the product.

10. A process as claimed in any of claims 1 to 9 wherein the stabilizer is employed in a 10:1 to 1:1 monomer:stabilizer weight ratio.

11. A process as claimed in claim 2 or in any of claims 3 to 10 as appendentto claim 2 wherein the polyol contains unsaturation.

12. A process for the preparation of a finely divided polymer carried out substantially as described in any oftheforegoing Examples 1 to 15.

13. Afinely divided polymer having a particle size of from 0.1 to 10 microns when prepared by a process as claimed in claim 1 or 12 or in any of claims 3 to 10 as appendentto claim 1.

14. A dispersion of a finely divided polymer as claimed in claim 13 in a liquid polyol.

15. A process for the preparation of a graft polymer dispersion carried out substantially as described in any of the foregoing Examples 16 to 27.

16. A dispersion when prepared by a process as claimed in claim 2, 11 or 15 or in any of claims 3 to 10 as appendentto claim 2.

17. A polyurethane foam when prepared from an organic polyisocyanate component and a dispersion as claimed in claim 14 or 16 in the presence of a blowing agent.