Method of making a low density, molded integral skin polyurethane foam

It has been found that non-chlorinated pentafluoropropane blowing agents may be used alone or in combination with water in a method of making flexible integral skin foams. For example, foams prepared using 1,1,1,3,3-pentafluoropropane (HFA-245fa) alone or in combination with water exhibit physical characteristics such as resistance to abrasion and cracking on flex comparable to conventional chlorinated fluorocarbon blown foams. The method of the the present invention produce foams which are suitable for use in many applications including, for example, shoe soles.

FIELD OF THE INVENTION 
The present invention relates to integral skin foams and a process for 
preparing such foams. More particularly, the invention relates to a method 
of making integral skin foams employing pentafluoropropane as the sole 
blowing or with water as a co-blowing agent. 
BACKGROUND OF THE INVENTION 
Integral skin foams are well known to those skilled in the art of 
polyurethane foams. Such foams have a cellular interior and a higher 
density microcellular or non-cellular skin. In general, to prepare such 
foams an organic isocyanate is reacted with a substance having at least 
one isocyanate reactive group in the presence of a catalyst, blowing 
agent, and a variety of optional additives. The reaction is carried out in 
a mold where a higher density skin forms at the interface of the reaction 
mixture and the relatively cool inner surface of the foam. 
Historically, the most common types of blowing agent used in integral skin 
polyurethane foams have been chlorofluorocarbons (CFCs) or combinations of 
CFCs and other blowing agents. However, in view of recent mandates calling 
for a reduction and eventually elimination of the use of CFCs, 
alternatives are considered necessary. 
Past methods of preparing integral skin polyurethanes with CFCs as a 
blowing agent includes G.B. Patent No. 1,209,297, which teaches the use of 
a combination blowing agent consisting of a CFC and hydrate of an organic 
compound which splits off water at temperatures above 40.degree. C. This 
blowing agent or combination of agents was used in a formulation with a 
suitable polyisocyanate, a polyol containing hydroxyl group and a 
catalyst. This patent discloses that free water in the system leads to a 
skin that is permeated with fine cells, which is undesirable. 
Attempts have been made to evaluate the performance of alternate blowing 
agents to CFCs. In a paper by J. L. R. Clatty and S. J. Harasin entitled, 
Performance of Alternate Blowing Agents to Chlorofluorocarbons in RIM 
Structural and Elastomeric Polyurethane Foams, presented to the Annual 
Polyurethane Technical/Marketing Conference, October 1989, the authors 
addressed the use of water as a blowing agent for integral skin 
polyurethane reaction injection molded systems (RIM). In this application, 
the water concentration in the system is controlled by the concentration 
and type of molecular sieves used. As in the Great Britain patent 
discussed previously, the water is not in a free form but bound in some 
manner. In this instance, the authors state that this process is limited 
to use in rigid foam systems; and the flexible integral skin formulations 
may best be served by using HCFCs or HCFC-22 as substitutes for CFCs. 
A recently employed integral skin foam formulation is described in U.S. 
Pat. No. 5,100,922 to Wada et al. which relates to a method for producing 
a molded product of integral skin polyurethane foam. The method comprises 
reacting and curing (1) a high molecular weight polyol comprising, as the 
main component, a polyoxyalkylene polyol having, as the main constituent, 
oxyalkylene groups of at least 3 carbon atoms and oxyethylene groups at 
its molecular terminals with the overall oxyethylene group content being 
not higher than 15% by weight and having a hydroxyl value of not higher 
than 80, (2) a crosslinking agent containing a compound having an aromatic 
nucleus and at least two active hydrogen containing groups selected from 
the group consisting of hydroxyl groups, primary amino groups and 
secondary amino groups, and (3) a polyisocyanate, in a mold in the 
presence of a catalyst and a hydrogen atom containing halogenated 
hydrocarbon foaming agent. While an extensive list of blowing agents are 
provided, the only pentafluoro compounds described are chlorinated 
compounds such as 3,3-dichloro-1,1,1,2,2-pentafluoropropane and 
1,3-dichloro-1,1,2,2,3-pentafluoropropane, which are considered 
undesirable. 
More recently U.S. Pat. No. 5,506,275, issued to Valoppi, the present 
inventor, which relates to the use of 1,1,1,2-tetrafluoroethane as an 
alternative to conventional chlorinated fluorocarbon blowing agents in 
integral skin foam formulations. While this patent offers an alternative 
to halogenated hydrocarbon blowing agents per se, 1,1,2-tetrafluoroethane 
(HFC-134a) boils at -26.5.degree. C. and thus requires special gas 
delivery systems to introduce and maintain the blowing agent in solution, 
especially in warm weather conditions, i.e., above 90.degree. F. As such, 
still further improvements in the art are considered necessary. 
It has been found that foams utilizing pentafluoropropane blowing agents 
and, in particular, 1,1,1,3,3-pentafluoropropane as the blowing agent 
alone or in combination with limited amounts of water can be prepared 
which meet the stringent requirements inherent to integral skin foam 
applications such as an acceptable appearance and must exhibit enhanced 
resistance to abrasion and cracking upon flex. Further, the 
pentafluoropropane blowing agents utilized in association with the present 
invention are generally soluble in resinous solution thus eliminating or 
greatly reducing the need for specialized gas delivery systems to maintain 
pressure on the system. 
SUMMARY OF THE INVENTION 
It is the object of the present invention to provide a flexible, low 
density, integral skin polyurethane foam capable of use in various 
applications comprising the reaction product of; 
a) a polyisocyanate component; and 
b) an active hydroxy functional polyol composition; in the presence of 
c) a blowing agent including a non-chlorinated pentafluoropropane and 
optionally water; 
d) a catalyst; and 
e) optionally one or more compounds selected from the group consisting 
essentially of chain extenders, a surfactant, an alcohol having from 10 to 
20 carbons, fillers, pigments, antioxidants, stabilizers and mixtures 
thereof. 
The general process comprises reacting a polyisocyanate component with an 
isocyanate reactive compound in the presence of a catalyst of a type known 
by those skilled in the art and a non-chlorinated pentafluoropropane 
blowing agent optionally in association with water as a co-blowing agent. 
A catalyst which assists in controlling foam formation may be used as well 
as a surfactant to regulate cell size and structure.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION 
The organic polyisocyanates used in the instant process contain 
aromatically bound isocyanate groups. Representative of the types of 
organic polyisocyanates contemplated herein include, for example, 
1,4-diisocyanatobenzene, 1,3-diisocyanato-o-xylene, 
1,3-diisocyanato-p-xylene, 1,3-diisocyanato-m-xylene, 
2,4-diisocyanato-1-nitrobenzene, 
2,5-diisocyanato-1-nitrobenzene,m-phenylene diisocyanate, 2,4-toluene 
diisocyanate, 2,6-toluene diisocyanate, mixtures of 2,4- and 2,6-toluene 
diisocyanate, 4,4'-biphenylmethane diisocyanate, 4,4'diphenylmethane 
diisocyanate, 3,3'-4,4'-diphenylmethane diisocyanate, and 
3,3'-dimethyldiphenylmethane-4,4'-diisocyanate; the triisocyanates such as 
4,4',4"-triphenylmethane triisocyanate, polymethylene polyphenylene 
polyisocyanate, and 2,4,6-toluene triisocyanate; and the tetraisocyanates 
such as 4,4-dimethyl-2,2'-5'-diphenylmethane tetraisocyanate. Especially 
useful due to their availability and properties are 2,4'-diphenylmethane 
diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylene 
polyphenylene polyisocyanate and mixtures thereof. 
These polyisocyanates are prepared by conventional methods known in the art 
such as the phosgenation of the corresponding organic amine. Included 
within the usable isocyanates are the modifications of the above 
isocyanates which contain carbodiimide, allophanate, alkylene or 
isocyanurate structures. Quasi-prepolymers may also be employed in the 
process of the subject invention. These quasi-prepolymers are prepared by 
reacting an excess of organic polyisocyanate or mixtures thereof with a 
minor amount of an active hydrogen containing compound determined by the 
well known Zerewitinoff Test, as described by Kohler in Journal of the 
American Chemical Society, 49, 3181 (1927). These compounds and their 
methods of preparation are well known in the art. The use of any one 
specific active hydrogen compound is not critical hereto; rather, any such 
compound can be employed herein. Generally, the quasi-prepolymers have a 
free isocyanate content of from 20 percent to 40 percent by weight. 
Mixtures of polymeric diphenylmethane diisocyanate (polymeric MDI) and 
carbodiimide or urethane modified MDI are preferred. 
The isocyanate reactive composition, otherwise referred to herein as an 
active hydroxy-functional polyol composition may include any suitable 
polyoxyalkylene polyether polyol 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-pentanediols, 1,5-pentanediol, 
1,6-hexanediol, 1,7-heptanediol, glycerol, 1,1,1-trimethylolpropane, 
1,1,1-trimethylololethane or 1,2,6-hexanetriol. Any suitable alkylene 
oxide may be used such as ethylene oxide, propylene oxide, butylene oxide, 
amylene oxide and mixtures of these oxides. The polyoxyalkylene polyether 
polyols may be prepared from other starting materials such as 
tetrahydrofuran and alkylene oxidetetrahydrofuran mixtures, epihalohydrins 
such as epichlorophydrin, 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 
polyocyethylene glycol, polyoxypropylene glycol, polyoxybutylene glycol, 
polytetramethylene glycol, block copolymers, for example, combinations of 
polyoxypropylene and polyoxyethylene glycols, poly-1,2-oxybutylene and 
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 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. Pat. 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 polymerization in a solvent such as described in U.S. Pat. 
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.degree. C. 
and 170.degree. C., preferably between 75.degree. C. and 135.degree. 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.degree. C. and 170.degree. C., preferably from 75.degree. C. to 
135.degree. 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. Pat. No. RE 28,715 and unsaturated polyols such as those described in 
U.S. Pat. No. 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 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. 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 a 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, 
trimethylopropane allyl ether, pentaerythritol allyl ether, pentaerythitol 
vinyl ether, pentaerythritol diallyl ether, and 1-butene-3,4-diol, 
unsaturated epoxides such as 1-vinycyclohexene 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 or a mixture of ethylenically unsaturated monomer or 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, 
.alpha.-methylstyrene, 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, nitrostyrene, N,N-dimethylaminostyrene, 
acetoxystyrene, methyl-4-vinylbenzoate, phenoxystyrene, p-vinyldiphenyl 
sulfide, p-vinylphenyl phenyloxide, 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.-acetam, inoacrylate, butyl 
acrylate, 2-ethylhexyl acrylate, phenyl acrylate, phenyl methacrylate, 
.alpha.-chloroacrylonitrile, methacrylonitrile, N,N-dimethylacrylamide, 
N,N-dibenzylacrylaminde, N-butylacrylamide, methacryl 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 butyrate, isopropenyl acetate, vinyl formate 
vinyl methacrylate, vinyl methoxyacetate, vinyl benzoate, vinyl iodide, 
vinyltoluene, vinyinaphthalene, vinyl bromide, vinyl fluoride, vinylidene 
bromide, 1-chloro-1-fluoroethylene, vinylidene fluoride, vinyl methyl 
ether, vinyl other, 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(.beta.-chloroethyl)vinyl 
phosphonate, vinyl ethyl sulfide, vinyl ethyl sulfone, N-methyl-N-vinyl 
acetamide, N-vinyl pyrrolidene, 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 itacotric acid, 
dichlorbutadiene, 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 total amount of active hydroxy-functional polyol composition employed 
in accordance with the teachings of the present invention includes from 
about 60 pbw to about 100 pbw based on a total of 110 parts by weight 
(pbw) for the resin and a foam index of between about 96-104. More 
preferably the total amount of active hydroxyl-functional polyol 
composition will be from about 65 pbw to about 95 pbw based on a total 
parts by weight of the resin of 110. 
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, 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, cumeme hydroperoxide, 
paramenthane hydroperoxide, di-.alpha.-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, 
propyl hydroperoxide, isopropyl hydroperoxide, n-butyl hydroperoxide, 
cyclohexyl hydroperoxide, trans-decalin hydroperoxide, 
.alpha.-methylbenzyl hydroperoxide, .alpha.-methyl-.alpha.-ethyl benzyl 
hydroperoxide, tetralin hydroperoxide, triphenyl methyl hydroperoxide, 
diphenylmethyl hydroperoxide, 
.alpha.,.alpha.'-azobis(2-methyl)heptonitrile, 
1,1-azo-bis(1-cyclohexane)carbonitrile, dimethyl 
.alpha.,.alpha.'azobis(isobutyroitrile), 4,4-'azobis(cyanopetanoic) acid, 
azobis(isobutyronitrile), 1-t-amylazo-1-cyanocyclohexane, 
2-t-butylazo-2-cyano-4-methoxy-4-methylpentane, 
2-t-butylazo-2-cyano-4-methylpentane, 2-(t-butylazo)isobutyronitrile, 
2-t-butylazo-2-cyanobutane, 1-cyano-1-(t-butylazo)cyclohexane, t-butyl 
peroxy-2-ethylhexanoate, t-butyl perpivalate, 
2,5-dimethylhexane-2,5-diper-2-ethylhexoate, t-butylperneo-decanoate, 
t-butyl perbenzoate, t-butyl percrotoate, 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 based on 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 on 
an ethylenically unsaturated monomer or mixture of such monomers and a 
second portio 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 3.0 and a molecular weight range of from about 3500 to 
about 5100. The most preferred polyols are polyethers which are copolymers 
of ethylene oxide and propylene glycol glycerine or trimethylolpropane. 
Include with this group are the previously described graft polymer 
dispersions. 
Any suitable catalyst may be used including tertiary amines such as 
triethylenediamine, N-methylmorpholine, N-ethylmorpholine, 
diethylethanolamine, N-cocomorpholine, 
1-methyl-4-dimethylaminoethylpiperazine, methoxypropyidimethylamine, 
N,N,N'-trimethylisopryl propylenediamine, 
3-diethylaminopropyldiethylamine, dimethylbenzylamine and the like. Other 
suitable catalysts are, for example, dibutylin dilaurate, dibutyltin 
d/acetate, stannous chloride, dibutyltin di-2-ethyl hexanoate, stannous 
oxide, available under the FOMREZ.RTM. trademark, as well as other 
organometallic compounds such as are disclosed in U.S. Pat. No. 2,846,408. 
An alcohol having from about 10 to about 20 carbons or mixtures thereof may 
be used in the present invention. 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 Chemica 
Augusta Spa or NEODOL.RTM. 25 produced by Shell. Such alcohols are known 
for enhancing cross-linking, thereby improving tear resistance. 
While surface active agents are generally not needed to solubilize the 
blowing agent of the present invention, in contrast to other known blowing 
agents, surface active agents, i.e., surfactants, may be employed, for 
example, to regulate the size cell size and structure of the resulting 
foams. Typical examples of such surface active agents include siloxane 
oxyalkylene heterol polymers and other organic polysiloxanes, oxyethylated 
alkyl phenol, oxyethylated fatty alcohols, fluoroaliphatic polymeric 
esters, 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 which may be employed in the present invention 
include those having two functional groups bearing active hydrogen atoms. 
A preferred group of chain extending agents includes ethylene glycol, 
diethylene glycol, propylene glycol, dipropylene glycol, or 1,4-butanediol 
and mixtures thereof. 
Additives which may be used in the process of the present invention include 
anti-oxidants, 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, 
plasticizers, such as gamma butylactone, fungistatic and bacteriostatic 
substances and fillers. 
The blowing agent of the present invention includes a non-chlorinated 
pentafluoropropane compound and particularly 1,1,1,3,3-pentafluoropropane, 
otherwise known as HFA-245fa. The pentafluoropropane blowing agent is used 
either alone or in conjunction with water in amounts sufficient to provide 
the desired foam density. Depending upon the amount of water employed as a 
co-blowing agent and the pack factor of the molded component, the amount 
of non-chlorinated pentafluoropropane blowing agent employed will 
generally range from about 0.5 pbw to about 10 pbw, and more preferably 
from about 1.0 to 8.0 pbw based on a total of 110 parts by weight of the 
resin for foams having molded densities of from 2 pcf to about 40 pcf. By 
way of non-limiting example, the amount of pentafluoropropane used as the 
sole blowing agent for a shoe sole or the like will generally range from 
about 1.5 pbw to about 5.0 pbw for foams having molded densities of from 
25 pcf to about 35 pcf at a molded pack factor of 1.5-3.0. By way of 
further example, the amount of pentafluoropropane used as a sole blowing 
agent for a steering wheel will generally range from about 2.0 pbw to 
about 8.0 pbw for foams having molded densities of from 25 pcf to about 35 
pcf with a pack factor of 2.0-6.0. As water is added as a co-blowing 
agent, the amount of non-chlorinated pentofluoro blowing agent is 
proportionately reduced. In general, up to about 0.25 pbw of water may be 
employed as a co-blowing agent and more preferably between about 0.05 pbw 
to about 0.17 pbw based on a total of 110 parts by weight of the resin. 
The mechanical parameters of the instant process are flexible and depend on 
the final application of the integral skin polyurethane foam. The reaction 
system is versatile enough that it may be made in a variety of densities 
and hardnesses. The system may be introduced into a mold in a variety of 
ways known to those skilled in the art. It may be shot into a preheated 
closed mold via high pressure injection technique. In this manner, it 
processes well enough to fill complex molds at low mold densities (from 19 
pcf to 25 pcf). It may also be run using a conventional open mold 
technique wherein the reaction mixture or system is poured or injected 
relatively at low pressure or atmospheric pressure into a preheated open 
mold. In the instant process, the system may be run at mold temperatures 
from about room temperature to about 120.degree. F. with room temperature 
being preferred. 
Having thus described the invention, the following examples are given by 
way of illustration with all amounts being given in parts by weight unless 
otherwise indicated. 
__________________________________________________________________________ 
Density ASTM D-1622 
Split Tear ASTM D-1938 
Tensile Strength ASTM D-412 
Graves Tear ASTM D-42 Die C 
Tensile Elongation ASTM 
Shore Hardness ASTM D-2240 
D412, Die A Ross Flex ASTM 
Taber Abrasion ASTM 1044 
1052 
__________________________________________________________________________ 
Polyol A is a propylene glycol initated polyoxypropylene 
polyoxyethylene block copolymer having a hydroxyl number 
of about 25 and a molecular weight of about 3850. 
Polyol B is a 31 percent solids, 1:1, acrylonitrile:styrene graft 
copolymer dispersed, in a trimethylolpropane initiated 
polyoxypropylene-polyoxyethylene block copolymer having a 
molecular weight of about 4120. The graft 
polymer dispersion has a hydroxyl number of about 25. 
Polyol C is a glycerine initiated polyoxypropylene-polyoxyethylene 
block copolymer having a hydroxyl number of about 
27 and a molecular weight of about 5050. 
XFE-1028 is an amine catalyst comprising a proprietary blend 
available from Air Products. 
T-12 is dibutyltin dilaurate. 
6-25 is an amine catalyst comprising a proprietary blend 
available from Air Products. 
WB 3092 is a prepolymer prepared from uretonimine modified 
isocyanate and propylene glycol having a free NCO 
content of 24 wt. % and a viscosity of 120 cps at 
25.degree. C. 
CFC-11 is 1 fluoro-1,1,1-frichloromethane. 
HFA-245fa is 1,1,1,3,3-pentafluoropropane. 
HFC-134a is 1,1,1,2-tetrafluoroethane. 
iso A is a solvent-free 50/50 weight percent blend of 
diphenylmethane diisocyanate and a urethane-modified 
polymethylene polyphenylpolyisocyanate prepolymer, wherein 
the blend has an isocyanate content of 23 
weight percent. 
__________________________________________________________________________ 
TABLE 1 
______________________________________ 
Foam Formulations 
1 2 3 4 5 6 7 8 
Component 
pbw pbw pbw pbw pbw pbw pbw pbw 
______________________________________ 
Polyol A 66.8 66.8 66.8 66.8 66.8 66.8 66.8 66.8 
Polyol B 20 20 20 20 20 
20 20 20 
Polyol C 7 7 7 7 7 7 7 7 
1,4-BDO 6 6 6 6 6 6 6 6 
EG 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 
XF-E1028 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 
T-12 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 
S-25 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 
CFC-11 5.2 7.5 
HFC-134A 2.1 2.5 
HFA-245fa 
2.7 5.1 
Water 0.2 0.2 0.2 0.2 0.2 0.2 0.38 0.50 
WB 3092 
OH #g 127.1 127.1 127.1 
127.1 
127.1 
127.1 
138.4 
145.5 
ISO A 38.78 37.96 39.94 
39.78 
39.71 
38.81 
ISO B 41.92 
44.13 
______________________________________ 
Initially it should be noted that the blowing agent was added in quantities 
to produce similar free rise densities for all solvent blown foams to 
ensure similar pack factors so that the skin thickness is caused only by 
the blowing agent condensing on the mold surface. As should be understood 
by those skilled in the art, the phrase pack factor is the ratio of the 
free rise density to the molded density of the resulting foam. 
Resin systems were foamed with the blowing agents being added such that a 
master batch of resin was produced combining all components except the 
blowing agent. Karl Fischer method for water determination was performed 
and residual water was determined to be 0.20%. This value was used to 
determine all resin/prepolymer ratios. The liquid blowing agents (CFC-11 
and HFA-245fa) were added to the resin system and then mixed. Blowing 
agent was added until a constant amount of blowing agent was obtained 
after mixing. Gaseous blowing agent (HFC-134a) was added to 2000 g of 
resin via a gas dispersion tube (20C Pyrex) from a pressurized cylinder 
(supplied by DuPont) equipped with a gas regulator. The resin was charged 
to a round bottom 3-neck flask. The resin was kept cool by placing the 
flask in an ice water bath while addition took place so that higher levels 
of HFC-134a could be added before saturation. A metal stir shaft connected 
to a motor kept the resin stirring at approximately 500 rpm. The third arm 
of the round bottom was connected to a cold finger with dry ice/isopropyl 
alcohol mixture for reflux of blowing agent. The cold finger was equipped 
with a bubbler to regulate the flow of gas. The addition was timed and 
final weight of blowing agent obtained by measuring the change in weight 
of the flask. A total percentage of blowing agent in the resin was then 
calculated. Water was also tested as a blowing agent by adding it directly 
to the resin and a Karl Fisher water determination was performed. 
Each of the resin blowing agent compositions were added directly into a 
quart Lily cup for foaming. Enough of the resin/blowing agent composition 
was added to produce foam which flowed over the lip of the quart cup so 
that free rise densities could be measured. The appropriate amount of 
prepolymer was weighed directly into the Lily cup. The mixture was then 
stirred for 7 seconds with a Vorath 31/2" mix blade at 2000 rpm. Foam 
cream, gel, top of cup, rise and tack free times were noted. The net 
weight of the foam produced was taken and foam density calculated: 
g.times.0.059=lb/ft.sup.3. The resultant free rise densities and 
reactivity profiles are given in TABLE II. 
TABLE II 
__________________________________________________________________________ 
Reactivities and Free Rise Densities 
1 2 3 4 5 6 7 8 
Blowing Agent 
CFC-11 
CFC-11 
HFC-134a 
HFC-134a 
HFA-245fa 
HFA-245fa 
Water 
Water 
__________________________________________________________________________ 
Cream Time 
18 15 11 12 15 12 17 15 
Gel Time 
33 
25 
21 24 26 29 30 
25 
Top of Cup 
44 
48 
30 25 32 32 49 
30 
Rise Time 
86 
70 
81 71 61 61 63 
58 
Tack Free 
59 
65 
60 64 48 59 44 
43 
Free Rise Density 
12.8 
9.4 
12.4 
9.4 12.6 8.9 16.5 
12.5 
__________________________________________________________________________ 
The foam components were weighed so that the final total weight is equal to 
the weight needed in the mold plus approximately 50 g hang-up in the Lily 
cup. The desired plaque molded density was 30 lb/ft.sup.3 (0.48 g/cc). 
After stirring, the foam was poured into a 12".times.6".times.3/8" 
aluminum mold heated to 120.degree. F. which has been sprayed lightly with 
silicone mold release. After 4 minutes, the plaque was demolded and 
trimmed. The net weight of the plaque was taken and foam density 
calculated (g/442 cc=g/ml). After 1 week curing time, physical properties 
were tested as reported in Table III below. 
As demonstrated in Table III, the cream time of HFA-245fa is slightly 
faster than CFC-11 but not quite as fast as R-134a. This is probably 
because the boiling point of HFA-245fa is in between that of CFC-11 and 
HFC-134a. Because of the volatility, HFA-245fa (b.p.=15.3.degree. C.) 
escapes faster from the resin than CFC-11 (b.p.=23.8.degree. C.) but not 
as fast as HFC-134a (b.p.=26.5.degree. C.). It may be deduced that 
HFA-245fa is therefore more soluble in the resin matrix than HFC-134a but 
not quite as soluble as CFC-11. Solubility studies were not carried out 
due to limited availability of HFA-245fa. The reported cream time of 
HFC-134a is not the actual cream but a frothing of the resin caused by the 
blowing agent boiling out. It is believed that the slightly faster cream 
of HFA-245fa compared with CFC-11 is due to the same boiling out effect 
but to a much lesser extent than HFC-134a. 
On a molar basis, HFA-245fa appears to be a more efficient blowing agent 
than CFC-11. At the lower free rise density (9 lb/ft.sup.3), HFA-245fa is 
not as efficient a blowing agent as HFC-134a but is equally efficient a 
blowing agent as HFC-134a at the higher free rise density of 12.5 
lb/ft.sup.3. 
When comparing the parts of blowing agent needed to produce a desired free 
rise density, HFA-245fa is a more efficient blowing agent than CFC-11 at 
both 9.0 and 12.5 lb/ft.sup.3 densities. When comparing blowing efficiency 
with HFC-134a, it can be seen that more blowing agent is required for both 
9.0 lb/ft.sup.3 and 12.5 lb/ft.sup.3. However, the cost associated with 
the added volume is believed to be more than offset by eliminating the 
need for specialized transfer and storage equipment, especially at higher 
temperatures. 
At the higher free rise density, namely 12.5 lb/ft.sup.3, HFA-245fa 
produced foam with superior tensile strength and tear strength to the 
HFC-134a blown foams (see TABLE III). The HFA-245fa blown foam properties 
are only slightly lower than those of CFC-11 blown foams with the 
exception of lower elongations and abrasion resistance. The abrasion 
resistance for the HFA-245fa foam (104 mg loss) is still well under the 
industry standard of less than 200 mg loss. It is believed that the 
slightly lower Ross Flex modulus at this free rise density is not 
indicative of poorer flex properties but instead due to a split in the 
hand mix foam. 
At 9 lb/ft.sup.3 free rise density, tensile and elongations are superior to 
those of the CFC-11 blown foams and all other physical properties are 
equal. Again, the properties of the HFA-245fa blown foam are far superior 
to that of the HFC-134a blown foam. The hardness of HFA-245fa blown foams 
is similar to that of CFC-11 blown foams. Foams blown with HFC-134a tend 
to be softer. 
As expected, all solvent blowing agents produced foams with superior 
physical properties to those of water blown foams. This is especially 
evidenced in tear strength. The water blown foams used for comparison had 
free rise densities of 16.5 lb/ft.sup.3 and 12.5 lb/ft.sup.3, 
respectively. The higher free rise density (16.5 lb/ft.sup.3) was used due 
to ease in handling and does not flash out of the mold or produce flow 
lines on final parts. The lower free rise density (12.5 lb/ft.sup.3) was 
used as comparison since the greatest pack factor could be obtained in a 
water blown formulation. 
Foams blown with HFC-245fa produce a well-defined thick skin as determined 
by Scanning Electron Microscopy (SEM). Skin thicknesses were not 
quantitatively measured due to the high variability in skin formation of 
hand mix plaques. It can be seen in comparison that at both 9 lb/ft.sup.3 
and 12.5 lb/ft.sup.3 free rise density, HFC-245fa blown foams exhibit skin 
thicknesses about equal to that of CFC-11 blown foams. HFC-245fa produced 
skins far superior to those foams blown with HFC-134a. Due to its high 
volatility, HFC-134a does not produce a thick-skinned foam. As expected, 
water exhibited very little true skin since no condensation is taking 
place at the mold surface. 
When used in an integral skin system, HFC-245fa produces foam with superior 
physical properties and skin thickness to foams blown with HFC-134a. When 
comparing the HFC-245fa blown foams to foams blown with CFC-11, HFC-245fa 
produced foams which rival CFC-11 blown foams in both physical properties 
and skin thickness. In practice, the use of HFC-245fa is believed to be an 
improvement over HFC-134a, since it is easier to handle, does not require 
special gas handling equipment, and produces foam with excellent physical 
properties and skin thickness. Further, foams employing HFC-245fa as a 
blowing agent, and particularly integral skin foams, can be used to form 
articles having a relatively broad molded density, i.e., from about 2.0 
pcf to about 40.0 pcf. 
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.