Note: Descriptions are shown in the official language in which they were submitted.
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Docket No. 3718
PASSENGER SIDE AIR BAG DOOR
VVITH AMINE FREE URETHANE FOAM SYSTEM
1. Field of the Invention
The present invention relates to supplementary impact restraint (SIR) hinged doors
and instrument panel, split-type doors, and more particularly, to polyurethane foams used
to make SIR hinged doors or instrument split-type panel openings, which do not contain
tertiary amine compounds while retaining a good balance of physical properties and
processing parameters.
2. Back~round of the Invention
Many motorized vehicles are equipped today with airbags as standard equipment to
improve the chances of avoiding injury in the event of a collision. On the passenger side,
the airbag can deploy in various fashions. The airbag may deploy directly through and split
the instrument panel, which is made of a semi-rigid foam and a vinyl skin. Alternatively,
the airbag may deploy through a hinged door attached to the instrument panel, which opens
and releases the airbag. For the airbag to deploy in time sufficient to protect the passenger
in the event of a collision, the airbag travels through the instrument panel or pushes open
the door at such a great speed that the integrity of the door or instrument panel structure
must be closely examined.
The basic structure of an airbag deployment opening in an instrument panel, or an
SIR hinged door, is a laminate of a polyurethane foam and a show surface skin which faces
into the passenger compartment. In the case of an instrument panel airbag opening, the
vinyl skin continuously covers the whole instrument panel, with that portion of the vinyl skin
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corresponding to where the airbag would deploy having stitch-like slits which provide weak
points through which the airbag can penetrate. Such a structure is described in Fukashimo
et al. 5,084,122. SIR hinged door structures are laminates of a substrate hinged to the
instrument panel, a polyurethane foam embedding the substrate, and a vinyl skin over the
foam on the show surface side. Upon deployment of the airbag, the SIR door swings open
along the hinge to release the airbag. Another alternative combines these two by employing
the first substrate hinged to the upper part of the instrument panel frame and a second
substrate hinged to the lower part of the instrument panel frame, each substrate being
embedded in a single polyurethane foam matrix and covered with a vinyl skin. The airbag
deploys through and splits in half the polyurethane foam and vinyl skin along a groove and
causes the upper half of the airbag door to swing open along the hinged part of the first
substrate while the lower half of the airbag door swings open along the hinged portion of
the second substrate.
Whether the deployment structure is a hinged door or a split-type instrument panel,
or a combination of the two, the overall structure is referred to herein as an SIR door.
Whenever the airbag deploys through the foam and vinyl of an SIR door, it is desirable to
avoid delamination of the foam from the substrate, if one exists, and delamination of the
vinyl skin from the polyurethane upon open airbag deployment. The polyurethane foam
should have good adhesion to vinyl skin, as well as sufficient tensile strength and elongation
at break, to avoid fragmenting. However, the tensile strength and elongation at break
properties cannot be so high that the polyurethane foam resists tear and prevents the airbag
from deploying. A balance of these properties is desirable.
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A further requirement of an SIR door is color maintenance over long periods of time.
One solution proposed to the problem of vinyl discoloration in Phillips et al 4,952,447 was
to provide a barrier layer between the vinyl skin layer and the polyurethane foam layer to
prevent the ingredients in one layer from migrating to the other layer. This barrier layer
is then said to prevent discoloration of the vinyl skin and hardening of the foam.
We have suspected that amine compounds such as catalysts which are not bound to
the polyurethane matrix are a potential source of vinyl skin discoloration. However, to date
polyurethane foams used in instrument panel formulations employ catalysts having tertiary
amine centers.
3. Summary of the Invention
It is an object of the invention to provide a polyurethane foam made in the absence
of catalyst compounds containing tertiary amines. It is a further object of the invention to
make a polyurethane foam having a good balance of physical properties to allow an airbag
to split the foam while reducing the possibility of foam and/or vinyl fragmentation.
There is now provided a passenger side SIR door comprised of a polyurethane foam
laminated to a skin where the polyurethane foam is obtained by reacting an organic
isocyanate and a polyol composition in the absence of any tertiary amine catalyst
compounds, and the foam possesses a tensile strength of 150 Kpa to 500 Kpa and an
elongation at break of 25 percent to 100 percent at densities of from 50 Kg/m3 to 130
Kg/m3. There is also provided a polyol composition suitable for the manufacture of the
polyurethane foam, containing a polyol blend of a graft polymer dispersed in a (a)
polyoxyalkylene polyether polyol having a functionality of less than three (3), terminated
21 S~81
with primary hydroxyl groups, and a (b) crosslinking polyol having a functionality of three
or more and a hydroxyl number of 200 or more; and the polyol composition is free of
tertiary amine catalyst compounds.
There is further provided a process for making the polyurethane foam and the
passenger side split-type airbag door which has a demold time of three (3) minutes or less.
4. Detailed Description of the Invention
The polyol composition of the invention is co~ Jlised of a polyol blend, a blowing
agent, tertiary amine-free catalysts, and optionally, other ingredients such as surfactants,
fillers, chain extenders, ultraviolet stabilizers, and flame retardants. The polyol blend
comprises a graft polymer dispersed in
(a) a polyoxyalkylene polyol having a functionality of less than three and
terminated with primary hydroxyl groups, and
(b) a polyol having a functionality of three or more and a hydroxyl number of 200
or more referred to herein as a crosslinking polyol.
One of the ingredients in the polyol blend is a graft polymer dispersed in the polyols
used in the polyol blend. For convenience, the graft polymer is referred to herein as a graft
polymer dispersion polyol, or a graft polyol, although it should be understood that the polyol
into which the graft polymer is dispersed can originally or ultimately be the (a) and (b)
polyols. The preparation of graft polymers polyols is known in the art and may be found
in columns 1-5 of U.S. Patent No. 3,652,639; columns 1-6 of U.S. Patent No. 3,823,201;
columns 2-8 of U.S. Patent No. 4,690,956; U.S. Patent No. 4,524,157, and Reissue Patents
No. 28,71~ and 29,014, all of which are incorporated herein by reference. Such methods of
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preparation include polymerization of one or more ethylenically unsaturated monomers onto
a polyether or polyester polyol having natural or induced unsaturation in the presence of
a free radical polymerization initiator and a reaction moderator/chain transfer agent.
The polymerization of an ethylenically unsaturated monomer or mixtures of
monomers is conducted in the presence of an effective amount of a free-radical initiator in
an unsaturated polyol mixture containing less than 0.1 mole of induced unsaturation per
mole of polyol mixture. The polymerization of an ethylenically unsaturated monomer or
mixture of monomers in the presence of an effective amount of a free radical initiator in
an unsaturation containing polyol mixture containing less than 0.1 mole of unsaturation per
mole of polyol mixture may employ as part of the mixture a polyether-ester polyol prepared
by the reaction of a polyoxyalkylene polyether polyol with maleic anhydride and an alkylene
oxide. This polyetherester polyol is isomerized by methods well known to those skilled in
the art. These include heat or isomerization catalysts such as morpholine, dibutylamine,
diethylamine, diethanolamine, thiols and the like. Also, the polyetherester polyol may be
prepared by the reaction of a polyoxyalkylene ether polyol, a polycarboxylic acid anhydride
to form a half acid ester and an alkylene oxide to obtain a product having an acid number
of less than S mg KOH/gram which comprises conducting the reaction between the
polyoxyalkylene polyether polyol and the anhydride and the following reaction with the
alkylene oxide in the presence of an effective amount of a catalyst selected from the group
consisting of salts and oxides of divalent metals. The polyols having induced unsaturation
are hereinafter referred to as "macromers." Chain transfer agents may be employed as
reaction moderators particularly at temperatures below 105~ C. The polymerization reaction
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may be carried out at temperatures between 25 C and 180 C, preferably between 80 C and
135C. The polyol mixture contains less than 0.1 mole of unsaturation per mole of polyol
rnixtures and ranges from 0.001 to 0.09 mole of unsaturation.
The alkylene oxides which may be employed for the preparation of the polyetherester
polyols include ethylene oxide, propylene oxide, butylene oxide, amylene oxide, and mixtures
of these oxides.
The graft polymer dispersions generally have viscosities less than 10,000 cps at 25 C.
Preferably, they have viscosities ranging from 2,000 to 8,000 cps at 25C.
Among those chain transfer agents which may be employed are as follows: acetic
acid, bromoacetic acid, chloroacetic acid, ethyl dibromoacetate, iodoacetic acid,
tribromoacetic acid, ethyl tribromoacetate, trichloroacetic acid, ethyl trichloroacetate,
acetone, p-bromophenylacetonitrile, p-nitrophenylacetylene, allyl alcohol, 2,4,6-
trinitroaniline, p-ethynylanisole, 2,4,6-trinitroanisole, azobenzene, benzaldehyde, p-
cyanobenzaldehyde, 2-butyl-benzene, bromobenzene, benzochrysene, benzoin, benzonitrile,
benzopyrene, tributylborane, 1,4-butanediol, 3,4-epoxy-2-methyl-1-butene, t-butyl ether, t-
butyl isocyanide, 1-phenylbutyne, p-cresol, p-bromocumene, dibenzonaphthacene, p-dioxane,
pentaphenyl ethane, ethanol, 1,1-diphenylethylene, ethylene glycol, ethyl ether, fluorene,
N,N-dimethylformamide, 2-heptene, 2-hexene, isobutyraldehyde, diethyl bromomalonate,
bromotrichloromethane, dibromoethane, diiodomethane, naphthalene, 1-naphthol, 2-
naphthol,methyloleate,2,4,4-triphenyl-1-pentene,4-methyl-2-pentene,2,6-diisopropylphenol,
phenyl ether, phenylphosphine, diethylphosphine, dibutylphosphine, phosphorus trichloride,
1,1,1-tribromopropane, dialkyl phthalate, 1,2-propanediol, 3-phosphinopropionitrile, 1-
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propanol, pyrocatechol, pyrogallol, methyl stearate, tetraethylsilane, triethylsilane,
dibromostilbene, a-bromostyrene, a-methylstyrene, tetraphenyl succinonitrile, 2,4,6-
trinitrotoluene, p-toluidine, N,N-dimethyl-p-toluidine, ~c-cyano-p-tolunitrile, a,a'-dibromo-p-
xylene, 2,6-xylenol, diethyl zinc, dithiodiacetic acid, ethyl dithiodiacetic acid, 4,4'-dithio-
bisanthranilic acid, benzenethiol, o-ethyoxybenzenethiol, 2,2'-dithiobisbenzothiazole, benzyl
sulfide, 1-dodecanethiol, ethanethiol, 1-hexanethiol, 1-naphthalenethiol, 2-naphthalenethiol,
1-octanethiol, 1-heptanethiol, 2-octanethiol, 1-tetradecanethiol, a-toluene-thiol, isopropanol,
2-butanol, carbon tetrabromide and tertiary dodecyl mercaptan.
The chain transfer agents employed will depend on the particular monomers or
mixtures of monomers employed and the molar ratios of such mixtures. The concentration
of the chain transfer agent which is employed may range from 0.1 to 10 percent by weight
based on the weight of the monomer.
Representative polyols essentially free from ethylenic unsaturation which may be
employed in combination with the macromers of the invention are well known to those
skilled in the art and are referred to herein as the "carrier" polyol. The carrier polyol may
be the same as the (a) polyol or may be a different kind of polyol from the (a) polyol. The
carrier polyol is 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 is evidenced by U.S. Patents 1,922,459;
3,190,927; and 3,346,557. Representative carrier polyols include polyhydroxyl-containing
polyesters,polyoxyalkylenepolyetherpolyols,polyhydroxy-terminatedpolyurethanepolymers,
polyhydroxyl-containing phosphorus compounds, and alkylene oxide adducts of polyhydric
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polythioesters, polyacetals, aliphatic polyols and thiols. Also, alkylene oxide adducts of
compounds which contain one SH group and one OH group may be used. Generally, the
number average molecular weight of the carrier polyols will vary from 1,000 to 10,000, and
preferably from 1,500 to 6,000.
Any suitable hydroxy-terminated polyester may be used such as are prepared, for
example, from polycarboxylic acids and polyhydric alcohols. Any suitable polycarboxylic acid
may be used such as oxalic acid, malonic acid, succinie acid, glutaric acid, adipic acid,
pimelic acid, suberic acid, azelaic acid, sebacic acid, brassylic acid, thapsic acid, maleic acid,
fumaric acid, glutaconic acid, a-hydromuconic acid, n-hydromuconic acid, a-butyl-a-ethyl-
glutaric acid, a,~-diethylsuccinic acid, isophthalic acid, terephthalic acid, hemimellitic acid,
and 1,4-cyclohexanedicarboxylic acid. Any suitable polyhydric alcohol, including both
aliphatic and aromatic, may be used such as ethylene glycol, propylene glycol, trimethylene
glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,4-pentanediol, 1,5-
pentanediol, 1,6-hexanediol, 1,7-heptanediol, glycerol, 1,1,1-trimethylolpropane, 1,1,1-
trimethylolethane, 1,2,6-hexanetriol, a-methyl glucoside, pentaerythritol, and sorbitol. Also
included with the term "polyhydric alcohol" are compounds derived from phenol such as 2,2-
bis(4-hydroxyphenyl)propane, commonly known as Bisphenol A.
Any suitable polyoxyalkylene polyether polyol may be used such as the polymerization
product of an alkylene oxide or a mixture of alkylene oxides with a polyhydrie 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
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these oxides. The polyoxyalkylene 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
polyoxyethylene glycols, poly-1,4-oxybutylene and polyoxyethylene glycols, and random
copolymer glycols prepared from blends of two or more alkylene oxides or by the sequential
addition of two or more alkylene oxides. The polyoxyalkylene polyether polyols may be
prepared by any known process such as, for example, the process disclosed by Wurtz in 1859
and Encyclopedia of Chemical Technology, Vol. 7, pp. 257-262, published by Interscience
Publishers, Inc. (1951) or in U.S. Patent No. 1,922,459. Polyethers which are preferred
include the alkylene oxide addition products of any glycol, trimethylolpropane, glycerine,
pentaerythritol, sucrose, sorbitol, and 2,2'-(4,4'-hydroxyphenyl)propane and blends thereof
having equivalent weights of from 100 to 5,000.
Suitable polyhydric polythioethers which may be condensed with alkylene oxides
include the condensation product of thiodiglycol or the reaction product of a dicarboxylic
acid such as is disclosed above for the preparation of the hydroxyl-containing polyesters with
any other suitable thioether glycol.
Polyhydroxyl-containing phosphorus compounds which may be used include those
compounds disclosed in U.S. Patent No. 3,639,542. Preferred polyhydroxyl-containin~
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phosphorus compounds are prepared from alkylene oxides and acids of phosphorus having
a P20s 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
allylene oxide such as those disclosed above.
Suitable aliphatic thiols which may be condensed with alkylene oxides include
alkanethiols containing at least two -SH groups such as 1,2-ethanedithiol, 1,2-propanedithiol,
1,3-propanedithiol, and 1,6-hexanedithiol; alkene thiols such as 2-butene-1,4-dithiol; and
alkyne thiols such as 3-hexyne-1,6-dithiol.
Less preferred amines which may be condensed with alkylene oxides include aromatic
amines such as aniline, o-chloroaniline, p-aminoaniline, 1,5-diaminonaphthalene, methylene
dianilinej the condensation products of aniline and formaldehyde, and 2,3-, 2,6-, 3,4-, 2,5-,
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 3,585,185; 3,639,541; and 3,639,542.
The unsaturated polyols or macromers which are employed in the present invention
may be prepared by the reaction of any conventional polyol such as those described above
with an organ;c compound having both ethylenic unsaturation and a hydroxyl, carboxyl,
_ 21 S5281
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, acrylic acid, acryoyl chloride, hydroxy ethyl acrylate or methacrylate 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-vinyl-cyclohexene-3,4-epoxide, butadiene monoxide, vinyl glycidyl ether(1-
vinyloxy-2,3-epoxy propane), glycidyl methacrylate and 3-allylo~y~ropylene oxide (allyl
glycidyl ether). If a polycarboxylic acid or anhydride is employed to incorporate
unsaturation into the polyols, it is preferable to react the unsaturated polyol with an alkylene
oxide, preferably ethylene or propylene oxide, to replace the carboxyl groups with hydroxyl
groups prior to employment in the present invention. The amount of alkylene oxide
employed is such as to reduce the acid number of the unsaturated polyol to about five (S)
or less.
The maleated macromers are isomerized at temperatures ranging from 80C to
120C for one-half hour to three hours in the presence of an effective amount of an
isomerization catalyst. The catalyst is employed at concentrations greater than 0.01 weight
percent based on the weight of the macromer.
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When preparing the polyetherester polyol employing the catalyst selected from the
group consisting of salts and oxides of divalent metals, the concentration of catalyst which
may be employed ranges from 0.005 to 0.5 weight percent based on the weight of polyol
mixture. The temperatures employed range from 75C to 175C. The equivalent weight
of the macromer may vary from 1,000 to 10,000, preferably from 2,000 to 6,000.
Among the divalent metals which may be employed are zinc acetate, zinc chloride,
zinc oxide, zinc neodecanoate, tin chloride, calcium naphthenate, calcium chloride, calcium
oxide, calcium acetate, copper naphthenate, cadmium acetate, cadmium chloride, nickel
chloride, m~ng:~nese chloride, and m~ng~nese acetate.
Certain of the above-mentioned catalysts such as calcium naphthenate promote the
isomerization of the maleate to the fumarate structure during the preparation of the
macromer while others, such as zinc chloride which is an effective catalyst for the
polymerization, inhibit this isomerization.
As mentioned above, the graft polymer dispersions of the invention are prepared by
the in situ polymerization in the above-described polyols 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, a-methylstyrene, 2-
methylstyrene, 3-methylstyrene, and 4-methylstyrene, 2,4-dimethylstyrene, ethylstyrene,
isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, and the like;
substituted styrenes such as cyanostyrene, nitrostyrene, N,N-dimethylaminostyrene,
acetoxystyrene, methyl 4-vinylbenzoate, phenoxystyrene, p-vinylphenol oxide, and the like;
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the acrylic and substituted acrylic monomers such as acrylonitrile, acrylic acid, methacrylic
acid, methyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, cyclohexyl methacrylate,
benzyl methacrylate, isopropyl methacrylate, octyl methacrylate, methacrylonitrile, ethyl a-
ethoxyacrylate, methyl a-acetaminoacrylate, butyl acrylate, 2-ethylhexyl acrylate, phenyl
acrylate, phenyl methacrylate, 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 butyrate, isopropenyl acetate, vinyl formate, vinyl
acrylate, vinyl methacrylate, vinyl methoxyacetate, vinyl benzoate, vinyltoluene,
vinylnaphthalene, vinyl methyl ether, vinyl ethyl ether, vinyl propyl ethers, vinyl butyl ethers,
vinyl 2-ethylhexyl ether, vinyl phenyl ether, vinyl 2-methoxyethyl ether, methoxybutadiene,
2-butoxyethyl ether, 3,4-dihydro-1,2-pyran, 2-butoxy-2'-vinyloxy diethyl ether, vinyl methyl
ketone, vinyl ethyl ketone, vinyl phosphonates such as vinyl phenyl ketone, vinyl ethyl
sulfone, N-methyl-N-vinyl acetamide, N-vinyl-pyrrolidone, vinyl imidazole, divinyl sulfoxide,
divinyl sulfone, sodium vinylsulfonate, methyl vinylsulfonate, N-vinyl pyrrole, and the like;
dimethyl fumarate, dimethyl maleate, maleic acid, crotonic acid, fumaric acid, itaconic acid,
monomethyl itaconate, t-butylaminoethyl methacrylate, dimethylaminoethyl methacrylate,
glycidyl acrylate, allyl alcohol, glycol monoesters of itaconic acid, 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.
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The amount of ethylenically unsaturated monomer employed in the polymerization
reaction is generally from 25 percent to 60 percent, preferably from 30 percent to 45
percent, based on the total weight of the product.
The polymerized product of the ethylenically unsaturated monomer and the
macromer is referred to herein as the "solids" phase, which is stably dispersed in the
polyether or polyester carrier polyols. The amount of solids by weight based on the weight
of the polyol composition is preferably 1 weight percent to 15 weight percent, more
preferably 3 weight percent to 8 weight percent.
Illustrative polymerization initiators which may be employed are the well-known free
radical types of vinyl polymerization initiators such as the peroxides, persulfates, perborates,
percarbonates, azo compounds, etc. These include 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-a-cumyl peroxide, dipropyl peroxide,
diisopropyl peroxide, isopropyl-t-butyl peroxide, butyl-t-butyl peroxide, difuroyl peroxide,
bis(triphenylmethyl) peroxide, bis(p-methoxybenzoyl) peroxide, p-monomethoxybenzoyl
peroxide, rubene peroxide, ascaridol, t-butyl peroxybenzoate, diethyl peroxyterephthalate,
propyl hydroperoxide, isopropyl hydroperoxide, n-butyl hydroperoxide, t-butyl hydroperoxide,
cyclohexyl hydroperoxide, trans-decalin hydroperoxide, a-methylbenzyl hydroperoxide, a-
methyl-a-ethyl benzyl hydroperoxide, tetralin hydroperoxide, triphenylmethyl hydroperoxide,
diphenylmethyl hydroperoxide, a,a'-azobis-(2-methyl heptonitrile), 1,1'-azo-bis(cyclohexane
carbonitri]e), 4,4'-azobis(4-cyanopentanoicacid), 2,2'-azobis(isobutyronitrile), 1-t-butylazo-1-
14
21S5281
cyanocyclohexane, persuccinic acid, diisopropyl peroxydicarbonate, 2,2'-azobis(2,4-
dimethylvaleronitrile), 2-t-butylazo-2-cyano-4-methoxy-4-methylpentane, 2,2'-azobis-2-
methylbutanenitrile, 2-t-butylazo-2-cyanobutane, 1,t-amylazo- 1-cyanocyclohexane, 2,2'-
azobis(2,4-dimethyl-4-methoxyvaleronitrile,2,2'-azobis-2-methyl-butyronitrile '7-t-butylazo-2-
cyano-4-methylpentane,2-t-butylazo-2-isobutyronitrile,tobutylperoxyisopropylcarbonateand
the like; a mixture of initiators may also be used. The preferred initiators are 2,2'-azobis(2-
methylbutyronitrile, 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2-t-
butylazo-2-cyano-4-methoxy-4-methylpentane, 2-t-butylazo-2-cyano-4-methylpentane, 2-t-
butylazo-2-cyano-butane and lauroyl peroxide. Generally, from about 0.1 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 process of the invention.
l'he polyol composition also comprises an (a) polyoxyalkylene polyether polyol which
has a functionality of less than 3 and is terminated with primary hydroxyl groups, preferably
oxyethylene groups. This polyether polyol may be the carrier polyol originally employed in
the in-situ preparation of the graft polymer dispersion, or it may be a different kind of
polyether polyol which is subsequently blended with the graft polymer dispersion, or it may
be blended with the carrier polyol of the intended graft polymer dispersion prior to the
onset of the graft polymerization reaction. While this second polyether polyol has been
separately listed in the description of the invention and claims, it should be understood that
the invention includes situations where the carrier polyol is the same polyol as the described
second polyether polyol having a functionality of less than 3 with primary hydroxyl unit
termination, Further, once the polyols of the polyol composition are blended, all the polyols
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can serve as the carrier polyol to the extent that the solids are said to be dispersed in
polyols. Thus, the polyol composition is merely required to contain at least a graft polymer,
or solids, dispersed in the (a) and (b) polyols, whether or not the (a) and (b) polyols are
subsequently blended with a graft polymer dispersion polyol or the (a) and (b) polyols are
used as carrier polyols during the graft polymerization reaction.
The (a) polyol may be prepared by the methods described above with respect to the
polyoxyalkylene polyether carrier polyols. The (a) polyol is terminated with primary
hydroxyl groups and preferably with oxyethylene units. The primary hydroxyl groups provide
quick reactivity with the isocyanate to reduce the demold time and enhance the physical
properties of the foam. More preferably, the amount of oxyethylene units capping the
polyol is at least 10 weight percent based on the number average weight of the (a) polyether
polyols. While not every polyol molecule may be capped with at least 10 weight percent of
oxyethylene units, the amount is determined by the average amount of oxyethylene units
among all the (a) polyol molecules. Thus, adding at least 10 weight percent of ethylene
oxide as the last addition step in the preparation of the polyol is one easy method of
ascertaining whether the polyol has at least 10 weight percent terminal oxyethylene units.
The (a) polyether polyols may be of a block, heteric, or block-heteric structure, so
long as an (a) polyol has primary hydroxyl group termination. The (a) polyether polyol also
preferably has a number average molecular weight of 1,000 to 10,000, more preferably, 1,500
to 6,000. The rem~ining units internal to the terminal oxyethylene block may be a block of
oxypropylene units, alternating blocks of oxypropylene and oxyethylene units, heteric
16
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structures thereof, or heteric-block structures thereof. Further, butylene oxide and amylene
oxide additions are also contemplated.
The (a) polyol also has a functionality of less than three to provide the desired
elongation properties. The (a) polyether polyol is preferably initiated with amine-free
compounds, more preferably compounds having only hydroxyl group functionalities.
To provide the desired crosslinking density and the resultant foam structural integrity,
there is provided a (b) crosslinking polyol having a functionality of three or more and a
hydroxyl number of 200 mg KOH/g polyol to 1,000 mg KOH/g polyol, preferably 400 to
800. The crosslinker polyol may be any polyol, including a polyoxyalkylene polyether polyol
or a polyester polyol, among the other polyols described above with respect to the carrier
polyol. The crosslinker polyol may have a heteric, block, or heteric-block structure and may
be terminated with primary and/or secondary hydroxyl groups. The crosslinker polyol has
preferably a number average molecular weight of 100 to less than 800, more preferably,
from 300 to 600.
When preparing the carrier polyol, the (a) polyoxyalkylene polyether polyol, and the
(b) crosslinker polyol, the initiators employed are preferably amine free to further reduce
the presence of tertiary amine centers. Thus, in a preferred embodiment, the polyol
composition is free of amine-initiated polyols and tertiary amine catalysts. The preferred
amount of (a) polyoxyalkylene polyether polyol can range from 80 weight percent to 97
weight percent. The amount of crosslinking (b) polyol ranges from greater than 2 weight
percent to 10 weight percent. Ie is believed that at 2 weight percent or less of crosslinker
polyol tlle crosslinking density may not be sumcient to provide the desired tensile strength
21~5281
and lower elongations. A more preferred range of the crosslinker polyol is from 4 weight
percent to 8 weight percent. The weight percents are based upon the weight of the polyol
composition.
In another embodiment of the invention, there is provided a polyol composition of
the (a) and (b) polyols along with the graft polymer dispersed therein or in other polyols
including the (a) and (b) polyols, the polyol composition having an average hydroxyl number
of 20 to 150 mg KOH/g polyol, and an average functionality of 2.4 to 3.2, more preferably,
an average hydroxyl number of 35 to less than 100 mg KOH/g, and an average functionality
of 2.6 to 3.0, most preferably, less than 3.0, all based only on the polyols present in the
composition. The solids content of the polyol blend in this embodiment is 1 to 15 weight
percent, more preferably, 3 to 8 weight percent. Also, in this embodiment, none of the
catalysts employed are tertiary amine catalysts; and preferably, none of the polyols are
amine initiated. When calculating the average functionality and hydroxyl numbers of the
polyol blends, the contribution made by ingredients such as water, surfactants, flame
retardants, and other additives, if present at all, is not to be taken into account. The
calculation is, however, based upon the presence of such polyols as are mentioned above
with respect to the carrier polyols, and chain extenders, if any are present, which have 2 or
more hydroxyl functionalities.
If desired, the polyol composition may contain chain extenders; but these are not
necessary. Chain-extending agents which may optionally be employed in the preparation of
the polyurethane foams include those compounds having at least two functional groups
bearing active hydrogen atoms, and preferab]y having molecular weight ranging less than
18
2lss28l
400, more preferably 60 to 300, such as water, hydrazine, primary and secondary diamines,
amino alcohols, amino acids, hydroxy acids, glycols, or mixtures thereo Alcohol chain-
extending agents include ethylene glycol, 1,3-propanediol, 1,10-decanediol, o,-m,-p-
dihydroxycyclohexane, diethylene glycol, 1,6-hexanediol, glycerine, trimethylol propane, 1,2,4-
, 1,3,5-trihydroxycyclohexane, bis(2-hydroxyethyl) hydroquinone, 1,4-butanediol.
The polyol composition contains a catalyst which promotes and greatly accelerates
the formation of polyurethane and/or polyisocyanurate linkages and is free of any tertiary
amine groups. The catalyst may also be further identified by other functions it performs,
such as a gel catalyst, a cure catalyst, a blow catalyst, or a delayed action catalyst, all of
which would also function to promote polyurethane/polyisocyanurate linkages. None of the
catalysts employed in the polyol composition contain any tertiary amine groups. The
catalyst used in the polyol composition may comprise a single catalyst compound
simultaneously promoting polyurethane and polyisocyanurate linkages, or two or more
different compounds.
Examples of suitable catalyst compounds include cure catalysts which also function
to shorten tack time, promote green strength, and prevent foam shrinkage. Suitable cure
catalysts are organometallic catalysts, preferably organotin catalysts, although it is possible
to employ metals such as lead, titanium, copper, mercury, cobalt, nickel, iron, vanadium,
antimony, and m~ng~nese. Suitable organometallic catalysts, exemplified here by tin as the
metal, are represented by the formula: RnSn[X-RI-Y]2, wherein R is a Cl-C8 alkyl or aryl
group, R1 is a C0-C~8 methylene group optionally substituted or branched with a Cl-C4 alkyl
group, Y is hydrogen or an hydroxyl group, preferably hydrogen, X is methylene, an -S-, an -
19
2l~s28l
SR2COO-, -SOOC-, an -03S-, or an -OOC- group wherein R2 is a Cl-C4 alkyl, n is 0 or 2,
provided that Rl is C0 only when X is a methylene group. Specific examples are tin (II)
acetate, tin (II) octanoate, tin (II) ethylhexanoate and tin (II) laurate; and dialkyl (1-8C) tin
(IV) salts of organic carboxylic acids having 1-32 carbon atoms, preferably 1-20 carbon
atoms, e.g., diethyltin diacetate, dibutyltin diacetate, dibutyltin diacetate, dibutyltin dilaurate,
dibutyltin maleate, dihexyltin diacetate, and dioctyltin diacetate. Other suitable organotin
catalysts are organotin alkoxides and mono or polyalkyl (1-8C) tin (IV) salts of inorganic
compounds such às butyltin trichloride, dimethyl- and diethyl- and dibutyl- and dioctyl- and
diphenyl- tin oxide, dibutyltin dibutoxide, di(2-ethylhexyl) tin oxide, dibutyltin dichloride, and
dioctyltin dioxide. Tin catalysts with tin-sulfur bonds which are resistant to hydrolysis can
be used, such as dialkyl (1-20C) tin dimercaptides, including dimethyl-, dibutyl-, and dioctyl-
tin dimercaptides. Other cure catalysts which are employed in another embodiment of the
invention are metal (bi) carbonates. These catalysts would act as a blowing agent if acidic
compounds were present in the polyol composition which could react to liberate carbon
dioxide gas. The metal of the carbonate or bicarbonate cure catalysts can be Li, ~Ja, Ki, Be,
Mg, Ca, Ba, St. The amount is not limited but preferred are 0.05 to 3 pbw, more preferably
0.1 to 1.5 pbw, based on 100 pbw of the polyols.
Catalysts which can also promote the formation of polyisocyanurate, or trimerization,
linkages along with polyurethane linkages include alkali salts, for example, sodium salts,
preferably potassium salts and ammonium salts, of organic carboxylic acids, expediently
having from 1 to 8 carbon atoms, preferably 1 or 2 carbon atoms, for example, the salts of
formic acid, acetic acid, prop;onic acid, or octanoic acid. Potassium acetate and potassium
21~52~1
formate are polyisocyanurate catalysts which are generally used. The amount of catalyst
usually used is from 1 to 10, preferably form 1.5 to 4 parts by weight, based on 100 parts by
weight of the total amount of polyols.
Any blowing agent can be used in the polyol composition, or where suitable, with an
isocyanate or blended as a separate feed stream into a dispensing head. The blowing agents
which can be used may be divided into the chemically active blowing agents which
chemically react with the isocyanate or with other formulation ingredients to release a gas
for foaming, and the physically active blowing agents which are gaseous at the exotherm
foaming temperatures or less without the necessity for chemically reacting with the foam
ingredients to provide a blowing gas. Included with the meaning of physically active blowing
agents are those gases which are thermally unstable and decompose at elevated
temperatures.
Examples of chemically active blowing agents are preferentially those which react
with the isocyanate to liberate gas, such as CO2. Suitable chemically active blowing agents
include, but are not limited to, water, mono- and polycarboxylic acids having a molecular
weight of from 46 to 300, and tertiary alcohols.
CO2 is the preferred gas employed for blowing. Water is preferentially used as a
blowing agent which produces the CO2 gas. Water reacts with the organic isocyanate to
liberate CO2 gas which is the actual blowing agent. However, since water consumes
isocyanate groups, an equivalent molar excess of isocyanate must be used to make up for
the consumed isocyanates.
2lss28l
-
The organic carboxylic acids used are advantageously aliphatic mon- and
polycarboxylic acids, e.g. dicarboxylic acids. However, other organic mono- and
polycarboxylic acids are also suitable. The organic carboxylic acids may, if desired, also
contain substituents which are inert under the reaction conditions of the polyisocyanate
polyaddition or are reactive with isocyanate, and/or may contain olefinically unsaturated
groups. Specific examples of chemically inert substituents are halogen atoms, such as
fluorine and/or chlorine, and alkyl, e.g. methyl or ethyl. The substituted organic carboxylic
acids expediently contain at least one further group which is reactive toward isocyanates, e.g.
a mercapto group, or preferably a primary and/or secondary hydroxyl group.
Suitable carboxylic acids are thus substituted or unsubstituted monocarboxylic acids,
e.g. formic acid, acetic acid, propionic acid, 2-chloropropionic acid, 3-chloropropionic acid,
2,2-dichlorpropionic acid, hexanoic acid, 2-ethyl-hexanoic acid, cyclohexanecarboxylic acid,
dodecanoic acid, palmitic acid, stearic acid, oleic acid, 3-mercapto-propionic acid, glycoli
acid, 3-hydroxypropionic acid, lactic acid, ricinoleic acid, 2-aminopropionic acid, benzoic
acid, 4-methylbenzoic acid, salicylic acid and anthranilic acid, and unsubstituted or
substituted polycarboxylic acids, preferably dicarboxylic acids, e.g. oxalic acid, malonic acid,
succinic acid, fumaric acid, maleic acid, glutaric acid, adipic acid, sebacic acid, dodecanedioic
acid, tartaric acid, phthalic acid, isophthalic acid and citric acid. Preferable acids are formic
acid, propionic acid, acetic acid, and 2-ethylhexanoic acid, particularly formic acid.
Combinations of any of the aforementioned chemically active blowing agents may be
employed, such as formic acid, and water.
21S5281
-
Physically active blowing agents are those which boil at the exotherm foaming
temperature or less, preferably at 50C or less. The most preferred physically active
blowing agents are those which have an ozone depletion potential of 0.05 or less. Examples
of physically active blowing agents are the volatile non-halogenated hydrocarbons having two
to seven carbon atoms such as alkanes, alkenes, cycloalkanes having up to 6 carbon atoms,
dialkyl ethers, cycloalkylene ethers and ketones; hydrochlorofluorocarbons (HCFCs);
hydrofluorocarbons (HFCs); perfluorinated hydrocarbons (HFCs); fluorinated ethers
(HFCs); and decomposition products.
Examples of volatile non-halogenated hydrocarbons include linear or branched
alkanes, e.g. butane, isobutane, 2,3 dimethylbutane, n- and isopentane and technical-gtade
pentane mixtures, n- and isohexanes, n- and isoheptanes, n- and isooctanes, n- and
isononanes, n- and isodecanes, n- and isoundecanes, and n- and isododecanes. Since very
good results are achieved with respect to the stability of emulsions, the processing properties
of the reaction mixture and the mechanical properties of polyurethane foam products
produced when n-pentane, isopentane or n-hexane, or a mixture thereof is used, these
alkanes are preferably employed. Furthermore, specific examples of alkenes are 1-pentene,
2-methylbutene, 3-methylbutene, and 1-hexene, of cycloalkanes are cyclobutane, preferably
cyclopentane, cyclohexane or mixtures thereof, specific examples of linear or cyclic ethers
are dimethyl ether, diethyl ether, methyl ethyl ether, vinyl methyl ether, vinyl ethyl ether,
divinyl ether, tetrahydrofuran and furan, and specific examples of ketones are acetone,
methyl ethyl ketone and cyclopentanone. Preferentially, cyclopentane, n- and isopentane,
n-hexane, and mixtures thereof are employed.
23
2ls528l
Any hydrochlorofluorocarbon blowing agent may be used in the present invention.
Preferred hydrochlorofluorocarbon blowing agents include 1-chloro-1,2-di~luoroethane; 1-
chloro-2,2-difluoroethane (142a); 1-chloro-1,1-difluoroethane (142b); 1,1-dichloro-1-
fluoroethane (14 lb); 1-chloro- 1,1,2-trifluoroethane; 1-chloro- 1,2,2-trifluoroethane; 1,1-
diochloro-1,2-difluoroethane; 1-chloro-1,1,2,2-tetrafluoroethane (124a); 1-chloro-1,2,2,2-
tetrafluoroethane(124); 1,1-dichloro-1,2,2-trifluoroethane; 1,1-dichloro-2,2,2-trifluoroethane
(123); and 1,2-dichloro-1,1,2-trifluoroethane (123a); monochlorodifluoromethane (HCFC-
22); 1-chloro-2,2,2-tri~luoroethane (HCFC-133a); gem-chlorofluoroethylene (R-1131a);
chloroheptaauoropropane (HCFC-217); chlorodifluoroethylene (HCFC-1122); and trans-
chlorofluoroethylene (HCFC-1131). The most preferred hydrochlorofluorocarbon blowing
agent is 1,1-dichloro-1-fluoroethane (HCFC-141b).
Suitable hydro~luorocarbons, perfluorinated hydrocarbons, and fluorinated ethers
include difluoromethane (HFC-32); 1,1,1,2-tetrafluoroethane (HFC-134a); 1,1,2,2-
tetrafluoroethane(HFC-134); 1,1-difluoroethane(HFC-152a); 1,2-difluoroethane(HFC-142),
trifluoromethane; heptafluoropropane; 1,1,1-tri~luoroethane; 1,1,2-trifluoroethane; 1,1,1,2,2-
pentafluoropropane; 1,1,1,3-tetrafluoropropane; 1,1,2,3,3-penta~luoropropane; 1,1,1,3,3-
pentafluoro-n-butane; hexafluorocyclopropane (C-216); octafluorocyclobutane (C-318);
perfluorotetrahydrofuran; perfluoroalkyl tetrahydlorulalls; perfluorofuran; perfluoro-propane,
-butane, -cyclobutane, -pentane, -cyclopentane, and -hexane, -cyclohexane, -heptane, and -
octane; perfluorodiethyl ether; perfluorodipropyl ether; and perfluoroethyl propyl ether.
24
21S5281
-
Decomposition type physically active blowing agents which release a gas through
thermal decomposition include pecan flour, and alkyl alkanoate compounds, especially
methyl and ethyl formates.
The total and relative amounts of blowing agents will depend upon the desired foam
density, the type of hydrocarbon, and the amount and type of additional blowing agents
employed. Polyurethane foam densities typical for rigid polyurethane SIR door applications
range from free rise densities of 50 Kg/m3 to 130 Kg/m3. The amount by weight of all
blowing agents is generally, based on 100 pbw of the polyols having at least two isocyanate
reactive hydrogens, from 0.05 to 45 pbw.
Water is typically found in minor quantities in the polyols as a byproduct and may
be sufficient to provide the desired blowing from a chemically active substance. Preferably,
however, water is additionally introduced into the polyol composition in amounts from 0.05
to 5 pbw, preferably from 0.5 to 4 pbw, based on 100 pbw of the polyols. The physically
active blowing agents, if employed, make up the remainder of the blowing agent for a total
of from 0.05 to 45 pbw.
Examples of suitable flameproofing agents are tricresyl phosphate, tris(2-chloroethyl)
phosphate, tris(2-chloropropyl) phosphate, and tris(2,3-dibromopropyl) phosphate.
In addition to the above-mentioned halogen-substituted phosphates, it is also possible
to use inorganic or organic flameproofing agents, such as red phosphorus, aluminum oxide
hydrate, antimony trioxide, arsenic oxide, ammonium polyphosphate (Exolit~) and calcium
sulfate, and expandable graphite. In general, from 2 to 50 parts by weight, preferably from
~... . . . .
2l~s28l
5 to 25 parts by weight, of said flameproofing agents may be used per 100 parts by weight
of the polyols.
For the purposes of the invention, fillers are conventional organic and inorganic
fillers and reinforcing agents; and preferentially, those fillers which are free of tertiary amine
waters are the one selected. Specific examples are inorganic fillers, such as silicate minerals,
for example, phyllosilicates such as antigorite, serpentine, hornblendes, amphiboles,
chrysotile, and talc; metal oxides, such as kaolin, aluminum oxides, titanium oxides and iron
oxides; metal salts, such as chalk, baryte and inorganic pigments, such as cadmium sulfide,
zinc sulfide and glass, inter alia; kaolin (china clay), aluminum silicate and coprecipitates
of barium sulfate and aluminum silicate, and natural and synthetic fibrous minerals, such
as wollastonite, metal, and glass fibers of various lengths. Examples of suitable organic
fillers are carbon black, colophony, cyclopentadienyl resins, cellulose fibers, polyamide
fibers, polyacrylonitrile fibers, polyurethane fibers, and polyester fibers based on aromatic
and/or aliphatic dicarboxylic acid esters, and in particular, carbon fibers.
The inorganic and organic fillers may be used individually or as mixtures and may
be introduced into the polyol composition or isocyanate side in amounts of from 0.5 to 40
percent by weight, based on the weight of the foaming mixture (the polyol composition and
the isocyanate); but the content of mats, nonwovens and wovens made from natural and
synthetic fibers may reach values of up to 80 percent by weight.
Examples of suitable surfactants are compounds which serve to support
homogenization of the starting materials and may also regulate the cell structure of the
plastics. Specific examples are salts of su]fonic acids, e.g., alkali metal salts or ammonium
26
2155281
salts of fatty acids such as oleic or stearic acid, of dodecylbenzene- or
dinaphthylmethanedisulfonic acid, and ricinoleic acid; foam stabilizers, such as siloxane-
oxyalkylene copolymers and other organopolysiloxanes, oxyethylated alkyl-phenols,
oxyethylated fatty alcohols, paraffin oils, castor oil esters, ricinoleic acid esters, Turkey red
oil and groundnut oil, and cell regulators, such as paraffins, fatty alcohols, and
dimethylpolysiloxanes. The surfactants are usually used in amounts of 0.01 to 5 parts by
weight, based on 100 parts by weight of the polyols.
The organic polyisocyanates include all essentially known aliphatic, cycloaliphatic,
araliphatic and preferably aromatic multivalent isocyanates. Specific examples include:
alkylene diisocyanates with 4 to 12 carbons in the alkylene radical such as 1,12-dodecane
diisocyanate, 2-ethyl-1,4-tetramethylene diisocyanate, 2-methyl-1,5-pentamethylene
diisocyanate, 1;4-tetramethylene diisocyanate and preferably 1,6-hexamethylene diisocyanate;
cycloaliphatic diisocyanates such as 1,3- and 1,4-cyclohexane diisocyanate as well as any
mixtures of these isomers, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane
(isophorone diisocyanate), 2,4- and 2,6-hexahydrotoluene diisocyanate as well as the
corresponding isomeric mixtures, 4,4'- 2,2'-, and 2,4'-dicyclohexylmethane diisocyanate as
well as the corresponding isomeric mixtures and preferably aromatic diisocyanates and
polyisocyanates such as 2,4- and 2,6-toluene diisocyanate and the corresponding isomeric
mixtures 4,4'-, 2,4'-, and 2,2'-diphenylmethane diisocyanate and the corresponding isomeric
mixtures, mixtures of 4,4'- and 2,4'-diphenylmethane diisocyanates and
polyphenylenepolymethylene polyisocyanates (polymeric MDI), as well as mixtures of
2155281
.
polymeric MDI and toluene diisocyanates. The organic di- and polyisocyanates can be used
individually or in the form of mixtures.
Frequently, so-called modified multivalent isocyanates, i.e., products obtained by the
partial chemical reaction of organic diisocyanates and/or polyisocyanates are used.
Examples include diisocyanates and/or polyisocyanates containing ester groups, urea groups,
biuret groups, allophanate groups, carbodiimide groups, isocyanurate groups, and/or
urethane groups. Specific examples include organic, preferably aromatic, polyisocyanates
containing urethane groups and having an NCO content of 33.6 to 15 weight percent,
preferably 31 to 21 weight percent, based on the total weight, e.g., with low molecular
weight diols, triols, dialkylene glycols, trialkylene glycols, or polyoxyalkylene glycols with a
molecular weight of up to 1500; modified 4,4'-diphenylmethane diisocyanate or 2,4- and 2,6-
toluene diisocyanate, where examples of di- and polyoxyalkylene glycols that may be used
individually or as mixtures include diethylene glycol, dipropylene glycol, polyoxyethylene
glycol, polyoAy~[opylene glycol, polyoxyethylene glycol, polyoxypropylene glycol, and
polyoxypropylene polyoxyethylene glycols or -triols. Prepolymers containing NCO groups
with an NCO content of 25 to 9 weight percent, preferably 21 to 14 weight percent, based
on the total weight and produced from the polyester polyols and/or preferably polyether
polyols described below; 4,4'-diphenylmethane diisocyanate, miAtures of 2,4'- and 4,4'-
diphenylmethane diisocyanate, 2,4,- and/or 2,6-toluene diisocyanates or polymeric MDI are
also suitable. Furthermore, liquid polyisocyanates containing carbodiimide groups having
an NCO content of 33.6 to 15 weight percent, preferably 31 to 21 weight percent, based on
the total weight, have also proven suitable, e.g., based on 4,4'- and 2,4'- and/or 2,2'-
28
21S~281
diphenylmethane diisocyanate and/or 2,4'- and/or 2,6-toluene diisocyanate. The modified
polyisocyanates may optionally be mixed together or mixed with unmodified organic
polyisocyanates such as 2,4'- and 4,4'-diphenylmethane diisocyanate, polymeric MDI, 2,4'-
and/or 2,6-toluene diisocyanate.
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, 2,4-toluene diisocyanate, 2,6-toluene
diisocyanate, mixtures of 2,4- and 2,6-toluene diisocyanate, hexamethylene diisocyanate,
tetramethylene diisocyanate, cyclohexane-1,4-diisocyanate, hexahydrotoluene diisocyanate
(and isomers), naphthalene-1,5-diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, 4,4'-
diphenylmethane diisocyanate, mixtures of 4,4'- and 2,4'-diphenylmethane 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 a~s 4,4',4"-triphenylmethane triisocyanate, and toluene 2,4,6-triisocyanate; and the
tetraisocyanatessuchas4,4'-dimethyldiphenylmethane-2,2'-5,5'-tetraisocyanateandpolymeric
polyisocyanates such as polymethylene polyphenylene polyisocyanate, and mixtures thereof.
Especially useful due to their availability and properties are 4,4'-diphenylmethane
diisocyanate, polymethylene polyphenylene polyisocyanate, or mixtures thereof for rigid
foams, or a mixture of the foregoing with toluene diisocyanates for semi-rigid foams.
Crude polyisocyanates may also be used in the compositions of the present invention,
such as crude toluene diisocyanate obtained by the phosgenation of a mixture of
toluenediamines or crude diphenylmethane isocyanate obtained by the phosgenation of
29
2lss28l
crude diphenylmethane diamine. The preferred or crude isocyanates are disclosed in U.S.
Pat. No. 3,215,652.
The polyurethane foam of the invention is made by reacting an organic isocyanate
with the polyol composition. The foam is open celled, meaning that at least 20 percent of
the foam cells are open. The foam may be classified as a semi-flexible molded foam and
is not an integral skin foam. The skin surface on the SIR door is separately manufactured
and l~min~ted to the polyurethane foam by expanding the polyurethane foaming mixture
against the surface of the skin.
In another embodiment of the invention, a polyurethane foaming mixture is
laminated and expanded in a mold against and behind a skin by pouring or injecting the
polyurethane foaming mixture into a mold having the skin laid up to the surface of one of
the mold halves.
As the skin, there may be mentioned thermoplastic polymers such as soft polyvinyl
chloride, polypropylene, polyethylene, ABS, polyester, polyamide, and polyurethanes. It is
preferred that the skin be formed of a vinyl compound, more preferably, polyvinyl chloride.
The skin may have grooves or recesses on either the show surface or on the foam surface
to define weaknesses through which the airbag can penetrate and split. Examples of such
grooves and methods of making are described in U.S. Patent No. 5,084,122, incorporated
herein by reference.
The polyurethane foam has a free rise density of 50 Kg/m3 to 130 Kg/m3, a tensile
strength of greater than 150 Kpa, and an elongation of greater than 25 percent. Preferably,
the foam has a tensile strength of 150 Kpa to 500 Kpa and an elongation of 25 percent to
2155281
-
100 percent to ensure that the foam will split easily enough without fragmenting. The
polyurethane foam is free of tertiary amine catalysts.
The polyurethane foam of the invention is also suitable in any part of the instrument
panel, or wherever a semi-flexible foam is used. It is desired to have a foam without the
presence of amine catalysts.
The following examples illustrate the nature of the invention and are not limiting the
scope of the invention:
Polyol A is an ethylene oxide, propylene oxide adduct of glycerine having
terminated with about 21 weight percent oxyethylene units and having
a nominal hydroxyl number of about 27 and a functionality of less than
3Ø
Polyol B is an ethylene oxide, propylene oxide adduct of trimethylolpropane
terminated with about 13 weight percent oxyethylene units and having
a nominal hydroxyl number of about 35 and a functionality of less than
3Ø
Polyol C is 31 weight percent graft polymer dispersion of a 1:1 weight ratio of
acrylonitrile to styrene dispersed in Polyol B, the dispersion having a
nominal hydroxyl number of about 24 and a functionality of less than
3Ø
Polyol D is a propylene oxide adduct of a pentaerythritol/propylene glycol
initiator mixture having a nominal hydroxyl number of 555 and a
functionality of greater than 3Ø
31
2I~281
Polycat46 is potassium acetate in ethylene glycol, a
polyurethane/polyisocyanurate promoting catalyst.
Iso A is polymethylene polyphenylene poly;socyanate having a free NCO
content of 31.5.
EXAMPLE 1
The formulation of 72.2 pbw of Polyol A, 20 pbw of Polyol C, 5 pbw of polyol D, 2.0
pbw of deionized water, 0.4 pbw of K2CO3, and 0.8 pbw of Polycat 46 were mixed with Iso
A at an isocyanate index of 110 for about ten (10) seconds and about 2400 rpm. The
reaction profile is as follows: 15 seconds cream time, 62 seconds string gel time, 67 seconds
top of cup time, 165 seconds tack free time, and a free rise density of about 76 Kg/m3.
EXAMPLE 2
The formulation of 72.2 pbw of Polyol A, 20 pbw of Polyol C, S pbw of polyol D, 1.92
pbw of deionized water, 0.8 pbw of K2CO3, and 0.8 pbw of Polycat 46 were mixed with Iso
A at an isocyanate index of 110 for about ten (10) seconds and about 2400 rpm. The
handmix was poured into a 200mm X 200mm X 40mm aluminum mold in an amount
sufficient to produce a foam having a molded density of 106.9 Kg/m3. The mold was
clamped shut, the foaming mixture allowed to foam, and the part was demolded within three
(3) minutes. The tensile strength and elongation of the foam was measured according to
ASTM D3574. The tensile strength was initially 314 Kpa. After heat aging, it was 245.6;
after humid aging, it was 261.4. The elongation was 31.5 percent initially, 30.0 percent after
21$S28l
heat aging, and 33.3 percent after humid aging. These properties would indicate suitable
limits for use in an SIR door.
EXAMPLE 3
The formulation of Example 2 was machine mixed in a high pressure impingement
mixing machine. The foaming mixture was poured into an airbag mold preheated to about
105F having a polyvinyl chloride skin fastened to a mold half and an aluminum insert laid
on the vinyl skin. The foam was poured, the mold shut, and the part was demolded in about
three (3) minutes. The foam embedded the aluminum insert and adhered to the vinyl skin.
The part was tested for fragmentation by deploying an airbag through the foam and vinyl.
The vinyl skin had a groove running across the center width of the door through which the
airbag could deploy. The part was tested at -35C and at 85C.
The results which were inspected for pass or failure were the breakline, the vinyl
integrity, the foam integrity, and the adhesion between the vinyl foam and aluminum insert.
The breakline was inspected to ensure that the vinyl and foam split along the groove on the
vinyl. The vinyl and foam integrity was inspected to ensure that the vinyl and foam had not
fragmented. The adhesion was inspected to ensure that the vinyl, foam, and aluminum
insert remained adhered.
At each foam temperature, the test results were as follows: breakline-pass, vinyl
integrity-pass, foam integrity-pass, adhesion between vinyl and foam-pass, adhesion between
foam and aluminum insert-pass.
The density of the deployed foams was about 124 Kg/m3; the adhesive strength in
a peel test was greater than 8 ~/cm initial; the tensile strength was initially 425 Kpa and
215S2~1
317 Kpa after heat aging; and the elongation was 50 percent initial and 47 percent after heat
aging for 1~ hours at 130 C.
