GB2053933A - Process for preparing graft copolymer dispersions and polyurethanes prepared therefrom - Google Patents

Abstract

Stable graft polymer dispersions are prepared employing in situ free radical polymerization of one or more ethylenically unsaturated monomers in a polyol as the graft substrate in the presence of a preformed graft polymer dispersion. The resulting dispersions can be used to form polyurethanes by reaction with organic polyisocyanates. The preformed graft polymer is preferably also one with a polyol backbone with free radically grafted branches.

Description

SPECIFICATION Process for preparing graft copolymer dispersions and polyurethanes prepared therefrom The present invention relates to stable graft polymer dispersions of low viscosity and high monomer conversion and polyurethanes prepared therefrom. More particularly, the invention relates to graft copolymer dispersions prepared by the in situ free radical polymerization of one or more ethylenically unsaturated monomers in a polyol.

The prior art, as evidenced by U.S. Patent Nos. 3,652,659, 3,875,258, 3,950,317, and Reissue Patent Nos. 28,71 5 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 in the presence of polyols. These patents disclose various methods of preparing graft polymer dispersions.

However, none of the prior art reveals an awareness of the desirability of using a preformed graft copolymer dispersion in addition to the polyol during the addition of ethylenically unsaturated monomer or monomers.

It has been discovered that difficult-to-use monomers such as styrene, as well as others, can be incorporated into graft polymer dispersions giving stable, low viscous dispersions.

The present invention provides an improved process for the preparation of low-viscosity stable polymer dispersions. We have found that good results can be obtained by incorporating a preformed graft copolymer dispersion in conjunction with the convention backbone polyol and polymerizing the final monomer therein. By the phrase "graft copolymer dispersion" as used herein is meant a product prepared by the in situ polymerization in the presence of a free radical catalyst of one or more ethylenically unsaturated monomers in a polyol. The backbone polyol can be a polyol of a type well known to those skilled in the art, for example polyoxyalkylene ether polyols or polyester polyols as disclosed herein. This backbone may or may not contain appreciable unsaturetion therein.

Employing the process of the instant invention enables polymer dispersions to be produced with appreciably lower viscosities than hitherto and these may then be employed with advantage in polyurethane preparations. Polyol dispersions which could not be prepared beforehand are now possible. The resulting exotherm of the polymerization reaction- is easier to control as large temperature fluctuations are minimized. The resulting dispersions furthermore appear to have a more uniform particle size distribution.

According to the invention there is provided a process for the preparation of a stable graft copolymer dispersion by the in situ free radical polymerization of one or more ethylenically unsaturated monomers in a polyol, wherein the free radical polymerization is conducted in the presence of a preformed graft copolymer dispersion.

The concentration of the preformed graft copolymer dispersion which is employed may be as little as one percent or as much as thirty percent based on the total polyol content. The preformed graft copolymer dispersion which is employed may be incorporated in the polyol that is initially added to the reactor or the graft copolymer dispersion may be added incrementally in the same manner that the monomer and catalyst are added to the reaction vessel. The backbone polyol may or may not contain any unsaturation within the molecule. Preferably, however, the backbone polyol contains within it at least 0.3 moles of unsaturation per mole of polyol.

The polyols which may be employed in 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. 28,71 5 and unsaturated polyols such as those described in U.S. Patent No.

3,652,659 and Reissue 29,014 may be employed in the invention. Representative polyols essentially free from ethylenic unsaturation which may be employed in 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. Patent 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 poiythioesters, 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 poryols 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, alpha-hydromuconic acid, beta-hydromuconic acid, alpha-butyl-alpha-ethyl-glutaric 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, tnmethylene 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'-hydroxyphenol)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, poly1,2-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 ofChemical 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 polycarboxylic acids set forth above or they may be made using the same components that make up the hydroxylcontaining 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.

Suitably 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 ,6-hexanedithiol; alkene thiols such as 2-butene-1 ,4-dithiol; and alkyne thiols 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 unsaturated polyols which may be employed in 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, trimethylolpropane 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 glycidyl 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 preferabie 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 to reduce the acid number of the unsaturated polyol to about one or less.

To prepare the unsaturated polyols for use in 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 OOC and 1300 C. Both acidic catalysts, such as Lewis acid catalysts and basic catalysts such as alkali metal hydroxides, may be used.

In addition, a noncatalyzed reaction may be used employing temperatures between 500C and 2000 C.

As mentioned above, the graft copolymer dispersions of the invention are prepared by the in situ polymerization, in the above-described polyols and a small amount of a preformed graft polymer dispersion, of an ethylenically unsaturated monomer or a mixture of ethylenically unsaturated monomers. Representative ethylenically unsaturated monomers which may be employed in the present invention include butadiene, isoprene, 1 ,4-pentadiene, 1 ,6-hexadiene, 1 ,7-octadiene, styrene, alphamethylstyrene, methylstyrene, 2 ,4-dimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, and the like; substituted styrenes such as chlorostyrene, 2,5-dichlorostyrene, bromostyrene, fluorostyrene, trifluoromethylstyrene, iodostyrene, cyanostyrene, n itrostyrene, N,N-dimethyla minostyrene, acetoxylstyrene, methyl-4-vinylbenzoate, phenoxystyrene, p-vinyl diphenyl 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 alphachloroacrylate, ethyl alpha-ethoxyacrylate, methyl alpha-acetaminocrylate, 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 arylate, 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(beta-chloroethyl) vinylphosphonate, vinyl phenyl ketone, vinyl ethyl sulfide, vinyl ethyl sulfone, N-methyl-N-vinyl acetamide, N-vinyl-pyrrolidone, vinyl imidazole, divinyl sulfide, divinyl sulfoxide, divinyl sulfone, sodium vinylsulfonate, methyl vinylsulfonate, N-vinylpyrrole, and the like; dimethyl fumarate, dimethyl maleate, maleic acid, crotonic acid, fumaric acid, itaconic acid, monomethyl itaconate, t-butylaminoethyl methacrylate, dimethylaminoethyl 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 and mixtures thereof.

The amount of ethylenically unsaturated monomer employed in the polymerization reaction is generally from one percent to 40 percent, preferably from 1 5 percent to 30 percent, based on the total weight of the product. The polymerization occurs at a temperature between about 800C and 1 700C, preferably from 850C to 1 350C.

Illustrative catalysts which may be employed are the well-known free radical types of vinyl polymerization catalysts, 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, diisopropylbenzene 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, ascaridoi, t-butyl peroxybenzoate, diethyl peroxyterephthalate, propyl hydroperoxide, isopropyl hydroperoxide, n-butyl hydroperoxide, t-butyl hydroperoxide, cyclohexyl hydroperoxide, trans-decalin hydroperoxide, alphamethylbenzyl hydroperoxide, alpha-methy-alpha-ethyl benzyl hydroperoxide, tetralin hydroperoxide, triphenylmethyl hydroperoxide, diphenylmethyl hydroperoxide, alpha-alpha'-azo-2-methyl butyronitrile, alpha,alpha'-2-methyl heptonitrile, 1 ,1 '-azo-1 -cyclohexane carbonitrile, dimethyl alpha,alpha' azoisobutyrate, 4,4'-azo-4-cyanopentanoic acid, azobis-(isobutyronitrile), 1 -t-amylazo-1 - cyanocyclohexane, persuccinic acid, diisopropyl peroxy dicarbonate, and the like; a mixture of catalysts may also be used. Azobis(isobutyronitrile) and 1 -t-amylazo-1 -cyanocyclohexane 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.

The polyurethane foams employed in the present invention are generally prepared by the reaction of a graft polyol 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, surfaceactive agents, stabilizers, dyes, fillers and pigments. Suitable processes for the preparation of cellular polyurethane plastics are disclosed in U.S. Reissue Patent 24,514 together with 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 prepolymer technique wherein an excess of organic polyisocyanate is reacted in a first step with the polyol 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 2,6-tolylene diisocyanate, hexamethylene-1 ,6-diisocyanate, tetrnmethylene-1 ,4-diisocyanate, cyciohexane-1 ,4-diisocyanate, 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'-tetraisocyanate. 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 polyols may be employed along with another polyhydroxylcontaining component commonly employed in the art. Any of the polyhydroxyl-containing components which are described above for use in the preparation of the graft polyols may be employed in the preparation of the polyurethane foams useful in 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, triethyiene diamine, N-methyl morpholine, N-ethyl morpholine, diethyl ethanolamine, N-cocomorpholine, 1-methyl- 4-dimethylamino 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 wetting agent or 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 wetting agents have been found satisfactory. Nonionic surfactants and wetting agents 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 illustrate 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-1564 Compression Set. D-395 In these examples, the composition of the polyols as designated by the letters A, B, etc., are as follows: Polyol A is prepared by reacting a 3:1 glycerine :propylene glycol mixture with propylene oxide followed by a reaction with a mixture of propylene oxide and allyl glycidyl ether, then reacted with ethylene oxide resulting in a product with a hydroxyl number of 33 containing 1 5 percent by weight ethylene oxide and 0.3 moles of allyl glycidyl ether per mole of initiator.

Polyol B is prepared by a free radical initiated polymerization of 20 percent by weight of acrylonitrile and Polyol A.

Polyol C is prepared by reacting a glycerine propylene oxide adduct with ethylene oxide followed by a reaction with a mixture of propylene oxide and allyl glycidyl ether resulting in a product with a hydroxyl number 50.0 containing 9 percent by weight ethylene oxide and 0.3 moles of allyl glycidyl ether per mole of glycerine.

Polyol D is prepared by a free radical initiated polymerization of 30 percent by weight of a 3 :1 mixture of acrylonitrile to styrene and Polyol C.

Polyol E is a condensation product of glycerine, propylene oxide and ethylene oxide having an OH number of 35 and containing 14 percent of ethylene oxide.

Polyol F is prepared by a free radical initiated polymerization of 30 percent by weight of a 3 :1 mixture of acrylonitrile :styrene and Polyol A.

Polyol G is prepared by a free radical initiated polymerization of 20 percent by weight of a 1:1.5 mixture of acrylonitrile styrene and Polyol A.

Polyol H is prepared by reacting a glycerine-propylene oxide adduct with ethylene oxide followed by a reaction with a heteric mixture of propylene oxide and allyl glycidyl ether resulting in a product with a hydroxyl number 50.0 containing 9 percent by weight ethylene oxide and 0.9 moles of allyl glycidyl ether per mole of glycerine.

EXAMPLE 1 A reaction vessel equipped with a thermometer, stirrer, nitrogen source, inlet means, and heat exchange means was charged with 57 parts of Polyol A and 85 parts of Polyol B. The charge was heated to 1 200C with stirring and under a slight nitrogen flow. To the stirred polyol blend was added, through a static mixer, a mixture of 106.3 parts of acrylonitrile and 3.2 parts of azobis(isobutyronitrile) in 368.1 additional parts of Polyol A. The mixture was fed over a 120 minute period at 1 200C while the catalyst polyol mixture was added during a 1 30 minute period at 1 200 C. Upon completion of the addition, the reaction mixture was maintained at 1 200C for 30 minutes.The reaction mixture was then stripped of volatiles for one hour at 1 200C under less than 1 millimeter of mercury. The stripped reaction product has a Brookfield viscosity of 3250 cps at 250C.

COMPARATIVE EXAMPLE A A reaction vessel equipped with a thermometer, stirrer, nitrogen source, inlet means, and heat exchange means was charged with 142 parts of Polyol A. The charge was heated to 1 200C with stirring and a slight nitrogen flow. To the stirred polyol was added, through a static mixer, a mixture of 3.2 parts of azobis(isobutyronitrile) in 283.1 additional parts of Polyol A simultaneously with a monomer addition of 106.3 parts of acrylonitrile. The monomer was fed over a 120 minute period while the catalyst-polyol mixture is added during a 130 minute period at 1200 C. Upon completion of the addition, the reaction mixture was maintained at 1 200C for 30 minutes.The reaction mixture was then stripped of volatiles for one hour at 1 200C under less than 1 millimeter of mercury. The stripped reaction product has a Brookfield viscosity of 45,400 cps at 250C.

EXAMPLE 2 A reaction vessel equipped with a thermometer, stirrer, nitrogen source, inlet means, and heat exchange means was charged with 57 parts of Polyol C and 85 parts of Polyol D. The charge was heated to 1 200C with stirring and under a slight nitrogen flow. To the stirred polyol blend was added, through a static mixer, a mixture of 106.3 parts of acrylonitrile, 3.2 parts of azobis(isobutyronitrile) in 368.1 additional parts of Polyol C. The mixture was fed over a 120 minute period at 1 200C while the catalyst polyol mixture was added during a 130 minute period at 1 200C. Upon completion of the addition, the reaction was maintained at 1 200C for 30 minutes.The reaction mixture was then stripped of volatiles for 30 minutes at 11 50C under less than 1 millimeter of mercury. The stripped reaction product has a Brookfield viscosity of 2225 cps at 250C.

COMPARATIVE EXAMPLE B A reaction vessel equipped with a thermometer, stirrer, nitrogen source, inlet means, and heat exchange means was charged with 142 parts of Polyol C. The charge was heated to 1 200C with stirring and a slight nitrogen flow. To the stirred polyol was added, through a static mixer, a mixture of 3.2 parts of azobis(isobutyronitrile) in 283.1 parts of Polyol C simultaneously with a monomer addition of 106.3 parts of acrylonitrile. The monomer was fed over a period of 90 minutes while the catalyst polyol mixture was added over a period of 100 minutes. Upon completion of the addition, the reaction mixture was maintained at 1 200C for 30 minutes. The reaction mixture was then stripped of volatiles for 30 minutes at 1 200C under less than 1 millimeter of mercury pressure.The stripped reaction product has a Brookfield viscosity of 8780 cps at 250C.

EXAMPLE 3 A reaction vessel equipped with a thermometer, stirrer, nitrogen source, inlet means, and heat exchange means was charged with 57 parts of Polyol E and 85 parts of Polyol D. The charge was heated to 1 200C with stirring at under a slight nitrogen flow. To the stirred polyol blend was added, through a static mixer, a mixture of 106.3 parts of acrylonitrile and 3.2 parts of azobis(isobutyronitrile) in 368.1 additional parts of Polyol E. The mixture was fed over a 120 minute period at 1 200C while the catalyst polyol mixture was added during a 130 minute period at 1200 C. Upon completion of the addition, the reaction mixture was maintained at 1 200C for 30 minutes.The reaction mixture was then stripped of volatiles for 30 minutes at 11 50C under less than 1 millimeter of mercury. The stripped reaction product had a Brookfield viscosity of 5050 cps at 250C.

COMPARATIVE EXAMPLE C A reaction vessel equipped with a thermometer, stirrer, nitrogen source, inlet means, and heat exchange means was charged with 142 parts of Polyol E. The charge was heated to 1 200C with stirring and under a slight nitrogen flow. To the stirred polyol was added, through a static mixer, a mixture of 3.2 parts of azobis(isobutyronitrile) in 283.1 additional parts of Polyol E simultaneously with the monomer addition of 106.3 parts of acrylonitrile over a 90 minute period while the catalyst polyol mixture was added over a period of 100 minutes. When all the polyol has been added, the reaction temperature was maintained at 1 200C and held for 30 minutes. The polyol was then stripped at 11 50C for 30 minutes at less than 1 millimeter of mercury pressure.The stripped reaction product had a Brookfield viscosity of 7760 cps at 350C.

EXAMPLE 4 A reaction vessel equipped with a thermometer, stirrer, nitrogen source, inlet means, and heat exchange means was charged with 261.2 grams of Polyol A and heated to 11 00C while stirring under a nitrogen atmosphere. To the stirred polyol was added, through a static mixer, a mixture of 35 parts of Polyol F and 3.4 parts of 1 -t-amylazo-1 -cyanocyclohexane in 223.4 parts of Polyol A simultaneously with a monomer addition of 137.6 parts of styrene. The monomer was fed over a 90 minute period while the catalyst-polyol mixture was added over a 120 minute period. When all the polyol had been added, the reaction temperature was raised to 1 300C and held for one hour. The polyol was then stripped at 1 300C for 30 minutes at less than 0.5 millimeters of mercury pressure.The stripped reaction product has a Brookfield viscosity of 21 80 cps at 250C.

COMPARATIVE EXAMPLE D A reaction vessel equipped with a thermometer, stirrer, nitrogen source, inlet means, and heat exchange means was charged with 269.7 parts of Polyol A and heated while stirring under a nitrogen atmosphere to 1 1 OOC. To the stirred polyol was added, through a static mixer, a mixture of 4.5 parts of 1 -t-amylazo-1 -cyanocyclohexane in 269.7 parts of Polyol A simultaneously with a monomer addition of 149.1 parts of styrene. The monomer was fed over a 90 minute period while the catalyst-polyol mixture was added over a period of 120 minutes. After all the polyol had been added, the reaction temperature was raised to 1 300C and held for one hour. The polyol was then stripped at 1 300C for 30 minutes at less than 0.5 millimeters of mercury pressure. The stripped reaction product had a Brookfield viscosity in excess of 100,000 cps at 250C.

EXAMPLE 5 A reaction vessel equipped with a thermometer, stirrer, nitrogen source, inlet means, and heat exchange means was charged with 261.2 parts of Polyol C and heated while stirring under a nitrogen atmosphere to 1200 C. To the stirred polyol was added, through a static mixer, a mixture of 42.5 parts of Polyol D and 4.09 parts of 1 -t-amylazo-1 -cyanocyclohexane in 218.7 parts of Polyol C simultaneously with a monomer addition of 136.4 parts of styrene. The monomer was fed over a period of 90 minutes while the catalyst-polyol mixture was added over a period of 120 minutes. After all the polyol had been added, the reaction temperature was raised to 1 300C and held for one hour. The polyol was then stripped at less than 0.5 millimeters of mercury pressure and 1 300C for 30 minutes.The stripped reaction product had a Brookfield viscosity of 1790 cps at 250C.

COMPARATIVE EXAMPLE E A reaction vessel equipped with a thermometer, stirrer, nitrogen source, inlet means, and heat exchange means was charged with 254.8 parts of Polyol C and heated while stirring under a nitrogen atmosphere to 1200 C. To the stirred polyol was added, through a static mixer, a mixture of 4.5 parts 1-t-amylazo-1-cyanocyclohexane in 254.81 parts of Polyol C simultaneously with a monomer addition of 149.1 parts styrene. The monomer was fed over a period of 90 minutes while the catalyst-polyol mixture was added over a period of 120 minutes. After all the polyol had been added, the reaction temperature was raised to 1 300C and held for one hour. The polyol was then stripped at 1 300C for 30 minutes at less than 0.5 millimeters of mercury pressure.The stripped reaction product had a Brookfield viscosity of greater than 100,000 cps at 250C.

EXAMPLE 6 A reaction vessel equipped with a thermometer, stirrer, nitrogen source, inlet means, and heat exchange means was charged with 291.91 parts of Polyol C and heated while stirring under a nitrogen atmosphere to 1200 C. To the stirred polyol was added, through a static mixer, a mixture of 3.75 parts of 1 -t-amylazo-1 -cyanocyclohexane in 208.0 parts of Polyol D simultaneously with 125.1 parts of styrene.

The monomer was fed over a period of 60 minutes and the catalyst-polyol mixture was fed over a period of 70 minutes. After all the catalyst-polyol mixture has been added, the reaction temperature was maintained at 1 200C for one hour. The polyol was then stripped at less than 0.5 millimeters of mercury pressure at 1 200C for 30 minutes. The stripped reaction product had a Brookfield viscosity of 6520 cps at 250C.

EXAMPLE 7 A reaction vessel equipped with a thermometer, stirrer, nitrogen source, inlet means, and heat exchange means was charged with 11 80.8 parts of Polyol H and heated to 1 200C while stirring under a nitrogen atmosphere. To the stirred polyol was added, through a static mixer, a mixture of 397.6 parts of Polyol D and 35.8 parts of 1 -t-amylazo-1 -cyanocyclohexane in 1193.0 parts of Polyol H simultaneously with a monomer addition of 1192.8 parts of styrene. The monomer was fed over a period of 120 minutes while the polyol mixture was fed over a period of 140 minutes. After all the polyol had been added, the reaction temperature was raised to 1300C and held for one hour.The polyol was then stripped at 1 300C for 30 minutes at less than 0.5 millimeters of mercury pressure. The stripped reaction product had a Brookfield viscosity of 5370 cps at 250C.

EXAMPLES 8-11 The above procedure of Example 7 was duplicated employing Polyol F and Polyol A with the indicated monomers and temperature with the resulting viscosities.

TABLE I Brookfield Reaction Viscosity, Example Monomer Temp. C cps @ 250C 8 methyl methacrylate 130 4750 9 ethyl acrylate 130 3140 10 bis(beta-chloroethyl)vinyl phosphonate 130 2030 11 2-ethylhexyl acrylate 130 1580 EXAMPLE 12 Polyurethane Foam Using a one-quart capacity cylindrical container equipped with the Lightning Model V-7 mixer fitted with a shrouded blade, a suitable quantity of polyol, water, conventional catalysts and silicone surfactant was added to the container. The mixture was stirred for about 30 seconds, allowed to set for about 1 5 seconds and then 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.

TABLE II Ingredients Polyol, parts a300.o b300.0 Water, parts 8.1 8.1 Silicone Surfactant, parts 4.0 4.0 Triethylenediamine 2.1 2.1 Dibutyltin Dilaurate 0.05 0.02 Isocyanate Index 105 105 Physica! Properties Rise Time, sec 100 100 Density, pcf 2.10 2.21 Tensile, psi 15.6 11.4 Elongation, % 130 153 Block Tear, pi 1.1 1.4 CLD, psi, 50% defl. 0.37 0.23 CLD, psi after humid ageing, 50% defl. 79.75 77.09 Compression Set, % 50% 74.4 57.4 90% 95.0 95.2 Compression Set, % after humid ageing 50% 62.2 75.8 90% 91.2 96.1 Air Flow, cfm 0.32 1.81 aPolyol as prepared in Example 4 above.

bPolyol as prepared in Example 9 above.

Claims (12)

1. A process for the preparation of a stable graft copolymer dispersion by the in situ polymerization in the presence of a free radical catalyst of one or more ethylenically unsaturated monomers in a polyol, wherein the free radical polymerization is conducted in the presence of preformed graft copolymer dispersion.

2. A process as claimed in claim 1 wherein acrylonitrile is polymerized.

3. A process as claimed in claim 1 wherein styrene is polymerized.

4. A process as claimed in claim 1 wherein a mixture of acrylonitrile and styrene is polymerized.

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

6. A process as claimed in any of claims 1 to 4 wherein the free radical catalyst is 1 -t-amylazo-1 - cyanocyclohexane.

7. A process as claimed in any of claims 1 to 6 wherein the initial content of preformed graft copolymer dispersion is from 1 to 30 percent by weight of the initial polyol content.

8. A process as claimed in any of claims 1 to 7 wherein the preformed graft copolymer dispersion has been obtained by polymerizing the same ethylenically unsaturated monomer in situ in the same polyol using the same free radical catalyst.

9. A process as claimed in any of claims 1 to 8 wherein the polyol contains at least 0.3 moles of unsaturation per mole of polyol.

10. A process for the preparation of a stable graft copolymer dispersion carried out substantially as described in any of the foregoing Examples 1 to 11.

11. Stable graft copolymer dispersions when prepared by a process as claimed in any of claims 1 to 10.

12. Polyurethanes obtained from stable graft copolymer dispersions claimed in claim 11 and organic polyisocyanates.