CA2234440A1 - Self skinning foams employing tertiary alcohols as blowing agents - Google Patents

Abstract

The invention pertains to low weight, relatively low density semi-rigid and rigid self skinning polyurethane foams having improved surface hardness and reduced porosity over known water blown foams. The polyurethane foam includes an isocyanate component and an isocyanate reactive component including a blowing agent comprising water and at least one tertiary alcohol.

Description

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TITLE
SELF SKINNING FOAMS EMPLOYING
TERTIARY ALCOHOLS AS BLOWING AGENTS

FIFl n OF THE INVENTION
The present invention relates to polyurethane foams, and more particularly, to foams ranging from flexible to rigid for use in the manufacture of various components including, but not limited to, automotive vehicle components. The molded foams of the present invention may be characterized as having densities ranging from between about 10 to about 60 pcf.

BACKGROUND OF THE INVENTION
Molded cellular and non-cellular polyurethane articles have found many applications in various industries including, for example, the automobile industry. Illustrative automotive applications include the formation of articlessuch as consoles, door panels, pillars, seat backs and spoilers, among others.
In general, such foams are prepared by reacting an organic isocyanate with a substrate having at least one isocyanate reactive group, in the presence of a catalyst blowing agent and various other additives. Until recently, the blowing agent employed in producing such foams and particularly those having a so-called integral skin used chlorofluorocarbons optionally with other blowing agents. More recently, water has been utilized as the chemical blowing agent CA 02234440 1998-0~-0~

as is described in U.S. Patent No. 5,132,329 entitled "Integral Skin Polyurethane Foam" by Lynch et al. and assigned to BASF Corporation; the disclosure of which is hereby expressly incorporated by reference.
While the process described according to the '329 reference gives rise to useful flexible, low density integral skin polyurethane foams, there is still a need in the art for foams having self skinning capabilities.
A perceived problem with regard to semi-rigid and rigid foams in particular is that although many polyurethane parts can be produced by molding with conventional water blown formulations, the resulting products tend to be rather porous, which is unacceptable for many applications. As a result ofthis undesired porosity, surfaces to be coated, particularly show surfaces, typically require multiple layers of one or more primer prior to coating.
In view of the foregoing, it is a primary object of the present invention to provide a composition for producing self skinning foams ranging from flexible torigid which have improved surface hardness and reduced porosity over known water blown rigid polyurethane foams.
It is a further object of the invention to provide a polyol composition useful for the production of self skinning polyurethane foams, wherein the polyol employed exhibits little or no separation behavior and the resulting 2 o articles are conducive to various coatings without requiring excessive pretreatment such as etching or priming unless desired.

SUMMARY OF THE INVFNTION
These and other objects are satisfied with the compositions of the present invention wherein the self skinning foam comprises: (a) a polyisocyanate component; (b) an isocyanate reactive component including at least one polyol, (c) an essentially chlorofluorocarbon free blowing agent including water and tertiary alcohol; (d) a catalyst; and (e) optionally, a chain extender, a surfactant, pigments and a stabilizer.
The invention also provides a polyol composition useful in the preparation of molded self skinning polyurethane products, comprising (a) an isocyanate reactive component including a polyol; (b) a blowing agent including water and at least one tertiary alcohol; (c) a catalyst; and (d) optionally, a chain extender, a surfactant, pigments and a stabilizer.
The invention also provides a method for forming self skinning polyurethane foams.

DETAII FD DESCRIPTION OF THE PREFFRRED EMBODIMENT
The present invention relates to compositions for forrning self skinning polyurethane foams comprising a polyisocyanate "A" side and a "B" side component including compounds containing isocyanate reactive hydrogens.
Included as part of the so-called "B" side component under at least one embodiment is a tertiary alcohol useful as a blowing agent and present in an CA 02234440 1998-0~-0~

amount of up to about 20.0 parts by weight based on the total parts by weight of the "B" component.
The phrase "self skinning foam" is a term of art and should be understood by those skilled in the art. By self skinning foam, it is essentiallymeant that the foam co",position causes the development of a skin at the surface of the molded product which is highly desirable for a number of different applications.
The organic polyisocyanates which may be employed for the "A" side component include aromatic, aliphatic, and cycloaliphatic polyisocyanates and combinations thereof. Representative of these types 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, 2,2'-, 2,4'-, and 4,4'-diphenylmethane diisocyanate, 4,4~-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 3,31-dimethyl-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 the2 0 tetraisocyanates such as 4,4'-dimethyldiphenylmethane 2,2'-5,5~-tetraisocyanate; and polymericpolyisocyanates such as polymethylene polyphenylene polyisocyanate.

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Especially useful due to their availability and properties are toluene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylene polyphenylene polyisocyanate and mixtures thereof.
Cnude polyisocyanates may also be used in the compositions of the present invention, such as crude diphenylmethane isocyanate obtained by the phosgenation of crude diphenylmethane diamine. The preferred or crude isocyanates are disclosed in U.S. Pat. No. 3,215,652.
Also useful are the modified polyisocyanates, examples of which include uretonimine-carbodiimide group containing polyisocyanates (German Patent No. 10 92 007), allophanate group containing polyisocyanates (British Patent No. 994,890; Belgium Patent No. 761,626), isocyanurate group containing polyisocyanates (German Patent Nos, 10 22 789, 12 22 067, 10 27 394, German Published Application Nos.19 29 034 and 20 04 048), urethane group containing polyisocyanates (Belgium Patent No. 752,261, U.S. Pat. No.
3,394,164), biuret group containing polyisocyanates (German Patent No. 11 01 394, British Patent No. 889,050) and ester group containing polyisocyanates (British Patent Nos. 965,474, 1,072,956, U.S. Pat. No. 3,567,763, German Patent No. 12 31 688), all of which are hereby incorporated by reference.
Preferably used are the easily accessible, optionally uretonimine-carbodiimide and urethane group-containing, aromatic di- and polyisocyanates such as 2,2'-, 2,4'-, 4,4'-diphenylmethane diisocyanate (MDI), CA 02234440 1998-0~-0~

as well as any desired mixtures of these isomers, and mixtures of 2,2'-, 2,4'-, 4,4'-diphenylmethane diisocyanate and polyphenyl polymethylene polyisocyanates (crude MDI). Preferably used is a uretonimine-carbodiimide-modified 4,4'-MDI composition containing from 10 weight percent to 40 weight percent modified MDI and 60 weight percent to 90 weight percent 4,4'-MDI, optionally containing less than 10 weight percent 2,2'-and 2,4'-MDI, the weight percentages based on the weight of the uretoniminecarbodiimide-modified 4,4'-MDI composition. The weight ratio of uretonimine to carbodiimide ranges from 20:1 to 1:1.
Quasi-prepolymers are also preferred, such as urethane-modified MDI
obtained by reacting a low molecular weight (~400) polyhydric compound with 4,4'-MDI, the final product containing, for example, from 40 weight percent to 60 weight percent urethane prepolymer and 40 weight percent to 60 weight percent 4,4'-MDI.
Other such modifications include forming a quasi-prepolymer by reacting a uretonimine-carbodiimide-modified, allophanate-modified, or biuret-modified MDI with a low or high molecular weight polyhydric compound.
The above-mentioned isocyanates may be used singly or as blends with other isocyanates to obtain the desired physical properties, viscosity, and freezing point. For example, crude MDI may be admixed with 4,4'-MDI and 2,4'-MDI; or one may blend the uretonimine-carbodiimide-modified MDI with a CA 02234440 1998-0~-0~

urethane-modified MDI and optionally crude MDI. Such blends may then, if desired, be reacted with a polyhydric compound to obtain a quasi-prepolymer.
For the "B" side component, otherwise referred to herein as the nonisocyanate component, any suitable polyoxyalkylene polyether polyol may be used such as those resulting from the polymerization of a polyhydric alcohol and an alkylene oxide. Representatives of such alcohols may include, 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, or1,2,6-hexanetriol. 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 polyoxyalkylene 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 2 0 polyoxyethylene glycols and copolymer glycols prepared from blends or sequential addition of two or more alkylene oxides. The polyoxyalkylene polyether polyols may be prepared by any known process such as, for CA 02234440 1998-0~-0~

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.
Other polyoxyalkylene polyether polyols which may be employed are those which contain grafted therein vinylic monomers.
The polyols which have incorporated therein the vinylic polymers may be prepared (1) by the in situ free-radical polymerization of an ethylenically unsaturated monomer or mixture of monomers in a polyol, or (2) by dispersion in a polyol of a preformed graft polymer prepared by free-radical polymerizationin a solvent such as described in U.S. Patent Nos. 3,931,092; 4,014,846;
4,093,573; and 4,122,056, the disclosures of which are herein incorporated by reference, or (3) by low temperature polymerization in the presence of chain transfer agents. These polymerizations may be carried out at a temperature between 65~C. and 170~C., preferably between 75~C. and 135~C.
The amount of ethylenically unsaturated monomer employed in the polymerization reaction is generally from one percent to 60 percent, preferably from 10 percent to 40 percent, based on the total weight of the product. The polymerization occurs at a temperature between about 80~C. and 170~C., preferably from 75~C to 135~C.
The polyols which may be employed in the preparation of the graft polymer dispersions are well known in the art. Both conventional polyols essentially free from ethylenic unsaturation such as those described in U.S.

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Pat. No. Re. 28,715 and unsaturated polyols such as those described in U.S.
Pat. Nos. 3,652,659 and Re. 29,014 may be employed in preparing the graft polymer dispersions used in the instant invention, the disclosures of which are incorporated by reference. Representative polyols essentially free from ethylenic unsaturation which may be employed are well known in the art. They are often prepared by the catalytic condensation of an alkylene oxide or mixtureof alkylene oxides either simultaneously or sequentially with an organic compound having at least two active hydrogen atoms such as evidenced by U.S. Pat. Nos. 1,922,459; 3,190,927; and 3,346,557, the disclosures of which are incorporated by reference.
The unsaturated polyols which may be employed for preparation of graft copolymer dispersions 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, CA 02234440 1998-0~-0~

pentaerythritol vinyl ether, pentaerythritol diallyl ether, and 1-butene-3,4-diol, unsaturated epoxides such as 1-vinylcyclohexene monoxide, butadiene monoxide, vinyl glycidyl ether, glycidyl methacrylate and 3-allyloxypropylene oxide.
As mentioned above, the graft polymer dispersions used in the invention are prepared by the in situ polymerization of an ethylenically unsaturated monomer of a mixture of ethylenically unsaturated monomers, either in a solvent or in the above-described 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, a-methylstyrene, methylstyrene, 2,5-dimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, and the like; substituted styrenes such as chlorostyrene, 2,4-dichlorostyrene, bromostyrene, fluorostyrene, trifluoromethylstyrene, iodostyrene, cyanostyrene, nitrostyrene, N,N-dimethylaminostyrene, acetoxystyrene, methyl-4-vinylbenzoate, phenoxystyrene, p-vinyldiphenyl sulfide, p-vinylphenyl phenyl 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 2 o methacrylate, cyclohexyl methacrylate, benzyl methacrylate, isopropyl methacrylate, octyl methacrylate, methacrylonitrile, methyl a-chloroacrylate, ethyl a -ethoxyacrylate, methyl a-acetam; inoacrylate, butyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, phenyl methacrylate, a-chloroacrylonitrile, methacrylonitrile, N,N-dimethylacrylamide, N,N-dibenzylacrylamide, N-butylacrylamide, N,N-dibenzylacrylamide, N-butylacrylamide, methacryl formamide, and the like; the vinyl esters, vinyl ethers, vinyl ketones, etc., such as vinyl acetate, vinyl chloroacetate, vinyl alcohol, vinyl butylrate isopropenyl acetate, vinyl formate, vinyl acrylate, vinyl methacrylate, vinyl methodxyacetate, 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 ether, vinyl butyl ether, vinyl 2-ethylhexyl ether, vinyl phenyl ether, vinyl 2-butoxyethyl ether, 2,4-dihydro-1,2-pyran, 2-butoxy-2~-vinyloxy diethyl ether, vinyl 2-ethylthioethyl ether, vinyl methyl ketone, vinyl ethyl ketone, vinyl phenyl ketone, vinyl phosphonates such as bis(b-chloro-ethyl) vinyl phosphonate, 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-vinyl pyrrole, and the like; dimethyl fumarate, dimethyl maleate, maleic acid,crotonic acid, fumaric acid, itaconic acid, monomethyl itaconate, 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 us in this invention. Preferably, the monomer is selected from the group consisting of acrylonitrile, styrene, methyl methacrylate and mixtures thereof.
Illustrative initiators which may be employed for the polymerization of vinyl monomers are the well-known free radical types of vinyl polymerization initiators, for example, peroxides, persulfates, perborates, per~;arl,onates, 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, cumeme hydroperoxide, paraminthane hydroperoxide, di-a-cumyl peroxide, dipropyl peroxide, diisopropyl peroxide, difuroyl peroxide, ditriphenylmethyl peroxide, bis(p-methoxybenzoyl) peroxide, p-monoethoxybenzoyl peroxide, rubene peroxide, ascaridol, t-butyl peroxybenzoate, diethyl peroxyterephthalate, propylhydroxperoxide, isopropyl hydroperoxide, n-butyl hydroperoxide, t-butyl hydroperoxide, cyclohexyl hydroperoxide, trans-decalin hydroperoxide, amethylbenzyl hydroperoxide, a-methyl-a-ethyl benzyl hydroperoxide, tetralin hydroperoxide, triphenylmethyl hydroperoxide, diphenylmethyl hydroperoxide, a-a'-azo-bis(2-methyl) butyronitrile, a,a'-azo-bis(2-methyl) heptonitrile, 1,1-azo-bis (1-cyclohexane carbonitrile, dimethyl a,a'-azo-bis(isobutyronitrile), 4,4'-azo-bis(4-cyanopetanoic) acid, azo-bis(isobutyronitrile), 1-t-amylazo-1-2 0 cyanocyclohexane, 2*butylazo-2-cyano4-methoxy4-methylpentane, 2-t-butylazo-2-cyano4-methylpentane, 2-(t-butylazo)isobutyronitrile, 2-t-butylazo-2-cyanobutane, 1-cyano-1-(t-butylazo)cyclohexane, t-butyl peroxy-2-CA 02234440 1998-0~-0~

ethylhexanoate, t-butylperpivalate, 2,5-dimethyl-hexane-2,5-diper-2-ethyl hexoate, t-butylperneo-decanoate, t-butylperbenzoate, t-butyl percrotonate, persuccinic acid, diisopropyl peroxydicarbonate, and the like; a mixture of initiators may also be used. Photochemically sensitive radical generators may also be employed. Generally from about 0.5 percent to about 10 percent, preferably from about 1 percent to about 4 percent, by weight of initiator basedon the weight of the monomer will be employed in the final polymerization.
Stabilizers may be employed during the process of making the graft polymer dispersions. One such example is the stabilizer disclosed in U.S. Pat.
No. 4,148,840 which comprises a copolymer having a first portion composed of an ethylenically unsaturated monomer or mixture of such monomers and a second portion which is a propylene oxide polymer. Other stabilizers which may be employed are the alkylene oxide adducts of copolymers of styrene-allyl alcohol.
The preferred polyols are polyethers having an average functionality of about 1.75 to about 5.0 and a molecular weight range of from about 300 to about 7000 depending upon whether the resulting product is intended to be flexible, semi-rigid or rigid. For example, the average functionality for flexible self skinning foams is about 2.0, for semi-rigid self skinning foams is about 2.5 and for rigid self skinning foams is greater than 3Ø Similarly, the molecular weight range for flexible self skinning foams is on the order of about 400 to about 4500, for semi-rigid foams would be about 400 to about 6500, and for CA 02234440 1998-0~-0~

rigid foams would be about 300 to about 6500. The most preferred polyols are polyethers which are copolymers of ethylene oxide and propylene oxide having a diol or triol initiator such as propylene glycol or glycerine.
The polyols utilized will be dependent upon the type of self skinning foam desired, i.e. flexible, semi-rigid or rigid. For example, in forming a flexible self skinning foam, the polyol component preferably will have an average hydroxyl content of between about 15 to about 32 with a minor amount of higher polyols optionally included. Polyols employed for the production of semi-rigid foams will typically have an average hydroxyl number of between about 107 to about 300 and polyols employed for the production of rigid self skinning foams will have an average hydroxyl content of between about 250 to about 2300.
Any suitable catalyst may be used including tertiary amines such as triethylenediamine, N-methylmorpholine, N-ethylmorpholine, diethylethanolamine, N-cocomorpholine, 1-methyl~-demethylaminoethylpiperazine, methoxypropyldimethylamine, N,N,N'-trimethylisopropyl propylenediamine, 3-diethylaminopropyldiethylamine, dimethylbenzylamine, and the like. Example of such commercially available catalysts is the DABCO~ series available through Air Products, Corp. Other suitable catalysts are, for example. dibutyltin dilaurate, dibutyltindiacetate, stannous chloride, dibutyltin di-2-ethyl hexanoate, stannous oxide, available CA 02234440 1998-0~-0~

under the FOMREZ~ trademark, as well as other organometallic compounds such as are disclosed in U.S. Patent No. 2,846,408.
In addition to the tertiary alcohols employed as blowing agents herein, other alcohols having from about 10 to about 20 carbons or mixtures thereof may be used according to the present invention for purposes of improving surface hardness, for example. Alcohols of this type are known to those skilled in the art. The types of alcohols contemplated are commonly produced via the oxo process and are referred to as oxo-alcohols. Examples of some commercially available products include LIAL 125 from Chimica Augusta SpA
or NEODOLtg) 25 produced by Shell.
A surface active agent is typically necessary for production of self-skinning polyurethane foam according to the present invention. Surfactants which may be used are those which aid in homogenizing the initial materials and may also be suitable for regulating cell structure. Typical examples are foam stabilizers such as siloxane oxyalkylene heterol polymers and other organic polysiloxanes, oxyethylated alkyl phenol, oxyethylated fatty alcohols, paraffin oils, castor oil ester, phthalic acid esters, ricindolic acid ester, and Turkey red oil, as well as cell regulators such as paraffins.
Chain extending agents employed in the preparation of self-skinning polyurethane foams include those having two functional groups bearing active hydrogen atoms. A preferred group of chain extending gents includes ethylene glycol, diethylene glycol, propylene glycol or 1,4-butanediol.

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Additives which may be used in the process of the present invention include known pigments, such as carbon black, dyes and flame retarding agents (e.g., tris-chloroethyl phosphates or ammonium phosphate and polyphosphate), stabilizers against aging and weathering, pl~stici7ers, such as gamma butyrolactone; fungistatic and bacteriostatic substances, and fillers.
In the self skinning polyurethane foam compositions of the present invention, a blowing agent is necessary. A mixture of water and tertiary alcoholis the preferred blowing agent and may be used in amounts of up to about 20.0 parts by weight based on the total of the nonisocyanate components, more preferably between about 2.0 and 20.0 parts by weight and still more preferably between about 6.0 to about 16.0 parts by weight based on the total of the nonisocyanate components. Although up to 20.0 parts by weight of the blowing agent may be employed, of this amount preferably the water content will be no more to 2.0 parts by weight, and still more preferably, no more than about 0.5 parts by weight based on the total weight of nonisocyanate components. Up to 2.0 parts of water is generally sufficient for generating CO2 to blow the density of the resulting foams down to levels low enough to mold light-weight products.
Further, the water which reduces the amount of tertiary alcohol needed tends to raise the flash point above approximately 100~F which is highly desirable.
As will be appreciated by those skilled in the art, the density of the foam generally decreases with increasing water content. In general, calculating the precise amounts of water and isocyanate required for the production of foams CA 02234440 1998-0~-0~

is considered to be routine to those skilled in the art of polyurethane and polyisocyanurate foams.
A method of manufacturing self skinning rigid polyurethane foam moldings involves mixing the nonisocyanate or"B" side components in a tank maintained at temperatures of from 75~F to about 125~F, preferably between about 85~F to about 95~F, to reduce the viscosity of the resin. The isocyanate "A" side component and the mixed "B" side component are then impingement mixed at a ratio of approximately 1:1 at a pressure of approxi"lately around 2000 psi and are injected at atmospheric pressure into a mold having the desired pressure for having the product, i.e. 150 - 200 psi. The mold itseif is generally preheated at from 100~F to 180~F, and preferably from 130~F to 150~F. After a period of one half of a minute to about four minutes, the resulting part is demolded.
The following examples illustrate the nature of the invention and are not intended to be limiting thereof.

Polyol A is a sucrose/DPG co-initiated polyether polyol which is propylene oxide capped having a hydroxyl content number of about 500.
Polyol B is a glycerine initiated polyether polyol which is propylene oxide capped having a hydroxyl content number of about 390 - 400.
SP 20373 Black is a pigment available from Pl~sticol~rs Inc. of Ashtabula, OH.

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DC 197 is an organosiloxane surface active agent.
Fomrez~ UL - 32 is a high performance organotic catalyst available from Witco Chemical.

The following examples including tertiary alcohols set forth in Table I
below illustrate various formulations of the self skinning rigid polyurethane foams of the present invention. The examples including diacetone alcohol have been provided for comparison purposes and do not constitute a forrnulation with the scope of the present invention.

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TABLE I

Polyol A 45.6 43.26 43.26 45.76 44.15 46.48 Polyol B 45.6 43.26 43.26 45.76 45.00 47.37 DC-197 2.3 2.3 2.3 2.3 2.3 2.42 DMCHA 1.0 1.8 1.8 1.8 1.8 1.89 H2O, deionized 0.18 0.18 0.18 0.18 0.25 0.26 t-butyl alcohol 10.0 - - 5.0 5.0 diacetone - 10.0 20.0 alcohol SP 20373 - - - - 1.5 1.58 UL-32 - 0.05 Total Parts by104.68 100.85 110.80 100.80 100.00 100.00 Weight With regard to the above-listed examples, it is contemplated that those formulations employing tertiary alcohol give rise to products having improved surface hardness and reduce porosity over those employing the diacetone alcohol. Further, it is expected that the self skinning foams of the present invention will give rise to flexible foams having a Shore A durometer hardness of at least about 25, the semi-rigid foams will have a Shore A durometer lo hardness of at least about 50 and the rigid foams will have a Shore D durometer hardness of at least about 75.
While it will be apparent that the preferred embodiments of the invention disclosed are well calculated to fulfill the objects stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the spirit thereof.

Claims (15)

1. A self-skinning foam comprising:
(a) a polyisocyanate component;
(b) an isocyanate reactive component comprising at least one polyol;
(c) an essentially chlorofluorocarbon-free blowing agent comprising water and at least one tertiary alcohol;
(d) a catalyst; and (e) optionally, a chain extender, a surfactant, pigments and a stabilizer.

2. A self skinning foam according to Claim 1 wherein said blowing agent is present in an amount of up to 20.0 parts by weight based on the total parts by weight of the nonisocyanate components.

3. A self skinning foam according to Claim 2 wherein said blowing agent is present in an amount between about 2.0 parts by weight to about 20.0 parts by weight based on the total parts by weight of nonisocyanate components.

4. A self skinning foam according to Claim 2 wherein said blowing agent is present in an amount of between about 6.0 parts by weight to about 16.0 parts by weight based on the total parts by weight of nonisocyanate components.

5. A foam according to Claim 1 wherein said tertiary alcohol is capable of withstanding mold temperatures of up to about 350°F without significant degradation.

6. A foam according to Claim 1 wherein said tertiary alcohol is a tertiary-butyl-alcohol.

7. A foam according to Claim 1 wherein the water component of the blowing agent is present in an amount of less than about 2.0 parts by weight based on the total weight of the nonisocyanate components.

8. A foam according to Claim 1 wherein said tertiary alcohol is capable of withstanding foam temperatures of about 350°F without significant degradation.

9. An isocyanate reactive composition comprising:
(a) at least one polyol;
(b) a blowing agent comprising water and at least one tertiary alcohol;

(c) a catalyst; and (d) optionally, a chain extender, a surfactant, pigments and a stabilizer.

10. An isocyanate reactive composition according to Claim 9 wherein said blowing agent is present in an amount of up to 20.0 parts by weight based on the total parts by weight of the composition.

11. An isocyanate reactive composition according to Claim 10 wherein said blowing agent is present in an amount between about 2.0 parts by weight to about 20.0 parts by weight based on the total parts by weight of the composition.

12. An isocyanate reactive composition according to Claim 10 wherein said blowing agent is present in an amount of between about 6.0 parts by weight to about 16.0 parts by weight based on the total parts by weight of the composition.

13. An isocyanate reactive composition according to Claim 9 wherein said tertiary alcohol is a tertiary-butyl-alcohol.

14. A foam according to Claim 9 wherein said tertiary alcohol is capable of withstanding foam temperatures of about 350°F without significant degradation.

15. A method of producing a self-skinning foam comprising reacting:
(a) a polyisocyanate component; and (b) an isocyanate-reactive component comprising a polyol;
in the presence of (c) an essentially chlorofluorocarbon-free blowing agent comprising water and a tertiary alcohol;
(d) a catalyst; and (e) optionally, a chain extender, a surfactant, pigments and a stabilizer.