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BACKGROUND OF THE INVENTION
This invention relates to high resilience polyurethane foams and more
particularly to the use of certain organosilicon polymers in the
production of such foams.
Basically such high resilience foams are produced by the reaction of highly
primary hydroxyl-capped, high molecular weight polyols with organic
isocyanates and water. High resilience polyurethane foams are
distinguishable in part from conventional hot cure polyurethane foams by
the use of such polyols and the fact that high resilience polyurethane
foams require little or no oven curing and thus are often referred to as
cold cure foams. Such foams are extremely desirable for cushioning
applications because of their excellent physical properties, e.g. very
high foam resiliency, low flammability, opencelled structure, low flex
fatigue (long life) and high SAC factors (load bearing properties).
Because of the high reactivity of high resilience foam ingredients and
their rapid buildup of gel strength, sometimes the foam can be obtained
without a cell stabilizer, however such foams typically have very
irregular cell structure as particularly evidenced by surface voids and
the discovery of a proper agent to help control cell structure has
remained a major problem in the art.
Attempts to solve this problem with surfactants generally employed in the
stabilization of hot cure polyurethane foam have not proven satisfactory
because such surfactants tend to overstabilize, causing extremely tight,
shrinkaging foam. Nor is the problem corrected by reducing the
concentrations of such surfactants, since at concentrations required to
eliminate shrinkage, the cells are no longer stabilized satisfactorily and
the foam structure becomes irregular, coarse and contains surface voids.
The use of low viscosity dimethylsilicone oils alone as stabilizers for
high resilience foams also has various disadvantages. For example, at low
concentrations they create metering and pumping problems in the processing
of the foam, while at higher concentrations these oils adversely affect
the physical properties of the foam. Solvents for such dimethylsiloxane
oils that are non-reactive with the foam ingredients e.g. alkanes,
hexamethyldisiloxane, and the like, can adversely affect the foam's
physical properties in proportion to their concentration and generally
create flammability hazards. Furthermore isocyanate reactive diluents,
such as polyether triols and the like which do not significantly change
the foam's properties, inasmuch as they react into the system and become
part of the foam structure, are not satisfactory solvents for
dimethylsilicone oils, since not enough oil can be dissolved to provide
foam stabilization at practical solution concentrations. High resilience
foams are also adversely affected by dimethylsilicones having more than
about ten dimethylsiloxy units per siloxane. For example only five or ten
weight per cent of such species in a dimethyl silicone oil can appreciably
degrade the foam's physical properties and even cause foam shrinkage.
Moreover, while particularly unique high resilience polyether urethane foam
can be prepared employing certain siloxane-oxyalkylene block copolymers as
disclosed in U.S. Pat. application Ser. No. 84,181 filed Oct. 26, 1970,
now U.S. Pat. No. 3,741,917, or certain aralkyl modified siloxane polymers
as disclosed in U.S. Pat. application Ser. No. 305,713 filed Nov. 13,
1972, now U.S. Pat. No. 3,839,384, or certain cyanoalkyl modified siloxane
fluids as disclosed in my copending U.S. application Ser. No. 325,327
filed Jan. 22, 1973, now abandoned said disclosures do not teach the use
of the novel organosilicon polymers employed in this invention.
SUMMARY OF THE INVENTION
It has been discovered that flexible high resilience polyether urethane
foam can be prepared according to the instant invention which involves
employing certain novel siloxane polymer fluids as more fully defined
below.
The siloxane polymer fluids employed in this invention have been found to
control the cell uniformity of high resilience polyether urethane foam
without obtaining tight foam and without introducing foam shrinkage or
causing any severe adverse effects to the foam's physical properties, e.g.
the foam's resilience and its resistance towards flammability. Moreover
voids in the foam are eliminated or at least greatly reduced by the
instant invention and the cell structure of the foam is also much more
uniform and finer than where no stabilizing agent is employed. This
discovery is surprising since as outlined above not all surfactants are so
suitable for use in the production of high resilience foams. Indeed even
siloxane polymer fluids of the same type employed herein, but outside the
scope of the instant invention, were found to cause shrinkage of the foam.
Therefore it is an object of this invention to provide a process for
producing high resilience polyether urethane foam. It is further an object
of this invention to provide novel organosilicon fluids for use in said
process. It is still another object of this invention to provide novel
compositions of said fluids for use in said process. It is also another
object of this invention to provide high resilience polyether urethane
foams produced by said process. Other objects and advantages of this
invention will become readily apparent from the following description and
appended claims.
More particularly this invention is directed, in part, to a process for
preparing high resilience polyether urethane foam, said process comprising
foaming and reacting a reaction mixture comprising:
I. an organic polyol selected from the group consisting of (A) a polyether
triol containing at least 40 mole percent primary hydroxyl groups and
having a molecular weight from about 2,000 to about 8,000 and (B) a
mixture of said polyether triol and other polyethers having an average of
at least two hydroxyl groups, said polyether triol of said mixture
amounting to at least 40 weight percent of the total polyol content;
II. an organic polyisocyanate, said organic polyol and said polyisocyanate
being present in the mixture in a major amount and in the relative amount
required to produce the urethane;
III. a blowing agent in a minor amount sufficient to foam the reaction
mixture;
IV. a catalytic amount of a catalyst for the production of the urethane
from the organic polyol and polyisocyanate; and
V. a minor amount of a cyanoalkoxy-alkyl modified siloxane fluid having the
average formula
(X).sub.z R.sub.3.sub.-z SiO(R.sub.2 SiO).sub.x [(X)(R)SiO].sub.Y
SiR.sub.3.sub.-z X.sub.z
wherein x has a value of 2 to 6 inclusive; y has a value of 0 to 6
inclusive; z has a value of 0 to 1 inclusive; R is a lower alkyl or phenyl
radical; and X is a cyanoalkoxy-alkyl radical of the formula --(O).sub.n
R'OR"CN wherein n has a value of 0 or 1, R' is an alkylene radical having
from 3 to 8 carbon atoms and R" is an alkylene radical having from 2 to 4
carbon atoms; said siloxane fluid containing at least one of said
cyanoalkoxy-alkyl radicals and having an average molecular weight in the
range of about 400 to 2000.
It is to be understood of course that the above process and the appended
claims read on employing a single ingredient of the type specified or any
of the various combinations of ingredient mixtures possible. For example,
in addition to employing a single ingredient of the types specified, if
desired, a mixture of triols, a mixture of polyisocyanates, a mixture of
blowing agents, a mixture of catalysts and/or a mixture of siloxane fluids
can be employed. Likewise the triol-polyether starting mixture could
consist of a single triol and a mixture of polyethers, a mixture of triols
and a single polyether or a mixture of two or more triols and two or more
polyethers.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As indicated above the cyanoalkoxy-alkyl modified siloxane fluid compounds
employed as the siloxane stabilizers for cell control in this invention
are characterized as having an average molecular weight range, as
containing internal dihydrocarbyl siloxy units (R.sub.2 SiO) and having
siloxy units containing a cyanoalkoxy-alkyl radical
[(NCR"OR'(O).sub.n)SiO]. It is of course to be understood that the
individual internal siloxy units can be the same or different and can be
arranged in any order. Subject to the above qualifications, a more
detailed description of the cyanoalkoxy-alkyl modified siloxane fluids is
presented below.
Accordingly the siloxane surfactants useful in this invention contain
internal dihydrocarbyl siloxy units, such as dimethylsiloxy,
diethylsiloxy, dipropylsiloxy, methylethylsiloxy, methylphenylsiloxy
groups and the like. Examples of internal cyanoalkoxy-alkyl siloxy units
that can be present in said siloxanes include, e.g. 3-(2-cyanoethoxy)
propylmethylsiloxy, 3-(2-cyanoethoxy) propyloxymethylsiloxy,
3-(2-cyanoethoxy)propylethylsiloxy,
3-(2-cyanoethoxy)-2-methylpropylmethyl-siloxy, 8-(2-cyanoethoxy)
octylmethylsiloxy, 3-(2-cyano-2-methylethoxy) propylmethylsiloxy,
3-(2-cyano-2-ethylethoxy) propylmethylsiloxy, and the like. Illustrative
end-blocking or chain terminating siloxy units of said siloxanes are such
terminal groups as trimethylsiloxy, triethylsiloxy, (3-(2-cyanoethoxy)
propyl) dimethylsiloxy, (3-(2-cyanoethoxy) propyloxy) dimethylsiloxy,
(3-(2-cyanoethoxy)-2-methylpropyl) dimethylsiloxy, (3-(2-cyano-2
-methylethoxy) propyl) dimethylsiloxy groups, and the like. Preferably R
is a methyl radical. Thus illustrative of the more preferred polymeric
siloxane fluids employed in the instant invention are trimethyl
end-blocked 3-(2-cyanoethoxy) propylmethylsiloxy-dimethylsiloxanes,
trimethyl end-blocked 3-(2-cyanoethoxy)
propyloxymethylsiloxy-dimethylsiloxanes, trimethyl end-blocked
3-(2-cyanoethoxy)-2-methylpropylmethylsiloxy-dimethylsiloxanes, trimethyl
end-blocked 3-(2-cyano-2-methylethoxy) propylmethylsiloxy
dimethylsiloxanes, trimethyl end-blocked 8-(2-cyanoethoxy)
octylmethylsiloxy dimethylsiloxanes, (3-(2-cyanoethoxy) propyl) dimethyl
end-blocked dimethylsiloxanes, (3-(2-cyanoethoxy) propyloxy) dimethyl
end-blocked dimethylsiloxanes, trimethyl end-blocked (3-(2-cyanoethoxy)
propylmethylsiloxy)
(3-(2-cyanoethoxy)-2-methylpropylmethylsiloxy)-dimethylsiloxanes,
(3-(2-cyanoethoxy) propyl) dimethyl end-blocked (3-(2-cyanoethoxy)
propylmethylsiloxy) dimethylsiloxanes, (3-(2-cyanoethoxy) propyloxy)
dimethyl end-blocked (3-(2-cyanoethoxy) propyloxymethylsiloxy)
dimethylsiloxanes, and the like. Most preferably the cyanoalkoxy-alkyl
radical is bonded directly to the silicon atom through one of its carbon
atoms, i.e. Si-C and not through an oxygen atom, i.e. Si-O-C.
Furthermore it is considered that the above cyanoalkoxy-alkyl modified
siloxane fluids having an average molecular weight in the range of about
400 to about 2000 employed as the cell stabilizers in this invention are
novel compounds per se. The preferred siloxane fluids are those having an
average molecular weight range of about 500 to about 1000, especially the
trimethyl end-blocked
(3-(2-cyanoethoxy)propylmethylsiloxydimethylsiloxanes.
The siloxane fluids of this invention can be produced by any number of
conventional methods well known in the art, as shown e.g. by U.S. Pat. No.
2,872,435 and U.S. application Ser. No. 279,883 filed Aug. 11, 1972, now
U.S. Pat. No. 3,846,462. Preferably the siloxane fluids containing
non-hydrolyzable cyanoalkoxy-alkyl radicals (Si-R'OR"CN) are prepared by
the platinum catalyzed addition of an olefinic cyano-substituted ether,
e.g. allyl-beta-cyanoethylether, to the corresponding hydrosiloxane at
temperatures of generally about 80.degree.C. to 90.degree.C. Such platinum
catalysts and platinum derivatives are well known in the art,
chloroplatinic acid is particularly effective. The platinum catalyst is
conveniently employed as a solution for example in tetrahydrofuran,
ethanol, butanol or mixed solvents such as ethanol-ethylene glycol
dimethyl ether. The general preferred concentration of platinum in the
catalyst based on the total weights of siloxane and olefinic derivatives
is about 5 to 100 parts per million, although higher and lower
concentrations may be used. Generally in carrying out the process it is
preferred to mix all the ingredients, except the platinum catalyst, at
about 25.degree.C. and allow the mixture to warm up to about 80.degree.C.
with external heating and at this temperature add the platinum catalyst.
An exothermic reaction is usually observed. The preferred temperature
range for the platinum catalyzed addition process is generally from about
60.degree.C. to 140.degree.C. Lower temperatures may be used but the
reaction times are slower. Higher temperatures may also be used, e.g. up
to 200.degree.C. but offer no apparent advantage. The choice of solvent if
used should of course be adapted to the preferred temperature range. The
removal or neutralization of the platinum (e.g. chloroplatinic acid)
catalyst is desirable for long range product stability. Usually sodium
bicarbonate is added to the reaction mixture to effect neutralization and
the resultant slurry filtered. Of course it is preferred to use a
stoichiometric excess of the olefinic cyano-substituted ether to insure
complete reaction of all of the silicon-hydrogen bonds. Alternatively the
siloxane fluids containing such non-hydrolyzable cyanoalkoxy-alkyl
radicals may also be prepared by the equilibration of corresponding
siloxanes, e.g. hexamethyldisiloxane, cyclic dimethylsiloxanes and
tetracyclic 3-(2-cyanoethoxy propylmethylsiloxane, using an acid or base
catalyst. For instance they can be prepared by equilibration using acid
catalysts such as anhydrous trifluoromethyl sulfonic acid, sulfuric acid
and the like in concentrations of about 0.1 to 2.0 weight per cent. The
equilibration is generally run at temperatures of about 25.degree.C. to
50.degree.C. with vigorous stirring at least until the mixture has become
homogeneous. Said siloxane fluids can also be prepared by equilibration
using a base catalyst, e.g. potassium silanolate, cesium hydroxide and
tetramethyl ammonium silanolate. Such catalysts are normally employed in
concentrations of 30-200 ppm as potassium equivalent. The equilibration
temperature depends on the catalyst employed. For instance, with
tetramethyl ammonium silanolate a temperature of about 75.degree. C. to
100.degree.C. is sufficient, preferably about 85.degree.C. to
90.degree.C., while the other alkaline catalysts usually require a
temperature of at least about 150.degree.C. Generally the equilibration
time is less than 5 hours.
The siloxane fluids containing hydrolyzable cyanoalkoxy-alkyl radicals
(SiOR'OR"CN) can be prepared by the catalyzed addition of
cyano-substituted hydroxyl terminated ethers of the formula HOR'OR"CN,
e.g. HOC.sub.3 H.sub.6 OC.sub.2 H.sub.4 CN, to the corresponding
hydrosiloxanes. Said addition type process is conventional and can be
promoted by a variety of catalysts such as organic derivatives of tin,
platinum and other transition metals. Preferred are the organic
derivatives of tin such as tin carboxylates, e.g. stannous octoate,
stannous oleate, stannous laurate, dibutyl tin dilaurate and the like. The
catalysts are generally used in amounts of about 0.1 to 5, usually no more
than about 2, weight per cent, based on the total weight of the reactants.
The reaction temperature generally ranges from about 60.degree.C. to
150.degree.C. (usually 80.degree.C. to 120.degree.C.). Such siloxane
fluids may also be prepared, if desired by reacting the cyano-substituted
hydroxyl terminated ethers with the corresponding alkoxysubstituted
siloxanes in the presence of a catalyst such as trifluoroacetic acid and
the like. Of course it is preferred to use a stoichiometric excess of
cyano-hydroxyl terminated ethers to insure complete reaction of all of the
silicon-hydrogen bonds.
The starting materials for the above processes as well as methods for their
preparation are of course all well known in the art. It is to be
understood, of course, that while the siloxane fluids used in this
invention can be discrete chemical compounds they are usually mixtures of
various discrete siloxane species, due at least in part, to the fact that
the starting materials used to produce the siloxane fluids are themselves
usually mixtures. Thus, it is to be also understood that the above average
formula representing the siloxane fluids as used herein incompasses the
presence of dihydrocarbon siloxanes as in the case of unsparged
equilibrated products and the possibility of the presence of small amounts
of other siloxy units, such as methyl (hydrogen) siloxy groups, in the
siloxane polymers due to an incomplete reaction or the nature of the
starting materials used to produce the siloxanes. Moreover the siloxane
fluids employed herein need not be fractionated, as by distillation but
may be sparged (i.e. stripped of lites) or unsparged.
The amount of active cyanoalkoxy-alkyl modified siloxane employed as the
foam stabilizer may fall within the range of about 0.03 to about 2 parts
by weight or greater, per hundred parts by weight of the organic polyol
starting material. Preferably the siloxane fluids are employed in amounts
ranging from about 0.08 to 0.6 parts by weight per 100 parts by weight of
the organic polyol starting materials.
The polyhydroxyl reactants (organic polyols) employed in this invention as
the starting materials to prepare the polyurethane foams can be any
polyether triol containing at least 40 mole percent of primary hydroxyl
groups and having a molecular weight from about 2,000 to about 8,000.
Conversely said polyether triols can contain no more than 60 mole per cent
of secondary hydroxyl groups. Preferably said polyether triols contain
about 60 to 90 mole per cent of primary hydroxyl groups and have a
molecular weight from about 4,000 to about 7,000.
The preferred polyether triols of this invention are polyalkylencether
triols obtained by the chemical addition of alkylene oxides to trihydroxyl
organic containing materials, such as glycerol; 1,2,6-hexanetriol;
1,1-trimethylolethane; 1,1,1-trimethylolpropane;
3-(2-hydroxyethoxy)-1,2-propanediol; 3-(2-hydroxypropoxy)-1,2-propanediol;
2,4-dimethyl-2-(2-hydroxyethoxy)methylpentanediol-1,5;
1,1,1-tris[(2-hydroxy-ethoxy)methyl] ethane;
1,1,1-tris[(2-hydroxypropoxy)methyl]-propane; and the like, as well as
mixtures thereof.
Alternatively the organic polyol starting materials of this invention can
be mixtures consisting essentially of said above defined polyether triols
and other polyether polyols having an average of at least two hydroxyl
groups, said above defined polyether triols amounting to at least 40
preferably at least 50, weight per cent of the total polyol content of
the mixtures. Illustrative of such other polyethers are triols outside of
the scope defined above, diols, tetraols and polymer/polyols, and the
like, as well as mixtures thereof.
Examples of such polyether polyols that can be mixed with the above defined
polyether triols include those adducts of alkylene oxide to such polyols
as diethylene glycol; dipropylene glycol; pentaerythritol; sorbitol;
sucrose; lactose; alpha-methylglucoside; alphahydroxylalkylglucoside;
novolac resins; water; ethylene glycol; propylene glycol; trimethylene
glycol; 1,2-butylene glycol; 1,3-butanediol; 1,4-butanediol;
1,5-pentanediol; 1,2-hexane glycol; 1,10-decanediol; 1,2-cyclohexanediol;
2-butene-1,4-diol; 3-cyclohexene-1,1-dimethanol;
4-methyl-3-cyclohexene-1,1-dimethanol; 3-methylene-1,5-pentanediol;
(2-hydroxyethoxy)-1-propanol; 4-(2-hydroxyethoxy)-1-butanol;
5-(2-hydroxypropoxy)-2-octanol; 3-allyloxy-1,5-pentanediol;
2-allyloxymethyl-2-methyl-1,3-propanediol; [4,4-pentyloxymethyl]-1,
3-propane-diol; 3-(o-propenyl-phenoxy)1,2-propanediol;
2,2-diisopropylidenebis(p-phenyleneoxy)-diethanol; and the like, or
phosphoric acid; benzenephosphoric acid; polyphosphoric acids such as
tripolyphosphoric acid and tetrapolyphosphoric acid; and the like; as well
as mixtures thereof.
Another type of polyether polyol that can be mixed with the above defined
polyether triols and used as the starting materials of this invention are
graft polymer/polyether compositions obtained by polymerizing
ethyleneically unsaturated monomers in a polyether as described in British
Pat. No. 1,063,222 and U.S. Pat. No. 3,383,351, the disclosures of which
are incorporated herein by reference thereto. Suitable monomers for
producing such compositions include, for example, acrylonitrile, vinyl
chloride, styrene, butadiene, vinylidine chloride, and the like. Suitable
polyethers for producing such compositions include, for example those
polyethers hereinabove-described. These graft polymer/polyether
compositions can contain from about 1 to about 70 weight per cent,
preferably about 5 to about 50 weight per cent and most preferably about
10 to about 40 weight per cent of the monomer polymerized in the
polyether. Such compositions are conveniently prepared by polymerizing the
monomers in the selected polyether at a temperature of 40.degree. to
150.degree.C. in the presence of a free radical polymerization catalyst,
such as peroxides, persulfates, percarbonates, perborates and azo
compounds as more fully described by the above patent references. The
resulting compositions may contain a small amount of unreacted polyether,
monomer and free polymer as well as the graft polymer/polyether complex.
Especially preferred are the graft polymer/polyethers obtained from
acrylonitrile and polyether triols.
The alkylene oxides employed in producing the preferred polyethers
described above normally have from 2 to 4 carbon atoms, inclusive while
propylene oxide and mixtures of propylene oxide and ethylene oxide are
especially preferred.
The exact organic polyol or polyols employed as the starting materials of
this invention merely depend on the end use of the high resilience
polyether urethane foam. For instance, the employment of polyether triols
having at least 40 mole per cent primary hydroxyl groups and molecular
weights from 2,000 to 8,000 preferably 4,000 to 7,000 generally have
hydroxyl numbers from 84 to 21, preferably 42 to 28 and give primarily
flexible polyether foams. The supplementary polyethers which may have any
proportion of primary to secondary hydroxyl groups and which may be mixed
with the required polyether triols can be used to control the degree of
softness of the foam or vary the load bearing properties of the foam. Such
limits are not intended to be restrictive, but are merely illustrative of
the large number of possible combinations of polyether triols and other
polyethers that can be employed.
The hydroxyl number is defined as the number of milligrams of potassium
hydroxide required for the complete neutralization of the hydrolysis
product of the fully acetylated derivative prepared from 1 gram of polyol
or mixtures of polyols with or without other crosslinking additives used
in the invention. The hydroxyl number can also be defined by the equation:
##EQU1##
wherein OH = hydroxyl number of the polyol.
A variety of organic isocyanates can be employed in the foam formulations
of this invention for reaction with the organic polyol starting materials
above described to provide high resilience polyether urethane foams.
Preferred isocyanates are polyisocyanates and polyisothiocyanates of the
general formula:
(QNCY).sub.i
wherein Y is oxygen or sulfur, i is an integer of two or more and Q is an
organic radical having the valence of i. For instance, Q can be a
substituted or unsubstituted hydrocarbon radical, such as alkylene and
arylene, having one or more aryl-NCY bonds and/or one or more alkyl-NCY
bonds. Q can also include radicals such as --QZQ--, where Q is an alkylene
or arylene group and Z is a divalent moiety such as --O--, --O--Q--O--,
--CO--, CO.sub.2, --S--, --S--Q--S--, --SO.sub.2 -- and the like. Examples
of such compounds include hexamethyl diisocyanate,
1,8-diisocyanateo-p-methane, xylylene diisocyanate, (OCNCH.sub.2 CH.sub.2
CH.sub.2 OCH.sub.2).sub.2 O, 1-methyl-2, 4-diisocyanatocyclohexane,
phenylene diisocyanates, tolylene diisocyanates, chlorophenylene
diisocyanates, diphenylmethane-4,4'-diisocyanate,
naphthalene-1,5-diisocyanate, triphenylmethane-4,4'-4"-triisocyanate, and
isopropylbenzene-alpha-4-diisocyanates.
Further included among the isocyanates useful in this invention are dimers
and trimers of isocyanates and diisocyanates and polymeric diisocyanates
such as those having the general formula:
(QNCY).sub.i and [Q(NCY).sub.i ].sub.j
in which i and i are integers of two or more, and/or (as additional
components in the reaction mixtures) compounds of the general formula:
L(NCO).sub.i
in which i is one or more and L is a monofunctional or polyfunctional atom
or radical. Examples of this type include ethylphosphonic diisocyanate,
C.sub.2 H.sub.5 P(O) (NCO).sub.2 ; phenylphosphonic diisocyanate, C.sub.6
H.sub.5 P(O) (NCO).sub.2 ; compounds containing a =Si-NCO group,
isocyanates derived from sulfonamides (QSO.sub.2 NCO), cyanic acid,
thiocyanic acid, and compounds containing a metal -NCO radical such as
tributyltinisocyanate.
More specifically, the polyisocyanate component employed in the
polyurethane foams of this invention also includes the following specific
compounds as well as mixtures of two or more of them: 2,4-tolylene
diisocyanate, 2,6-tolylene diisocyanate, crude tolylene diisocyanate,
bis(4-isocyanatophenyl)methane, polymethylene polyphenylisocyanates that
are produced by phosgenation of anilineformaldehyde condensation products,
dianisidine diisocyanate, toluidine diisocyanate, xylylene diisocyanate,
bis(2-isocyanatoethyl)-fumarate, bis(2-isocyanatoethyl) carbonate,
1,6-hexamethylene-diisocyanate, 1,4-tetramethylene-diisocyanate,
1,10-deca-methylene-diisocyanate, cumene-2,4-diisocyanate,
4-methoxy-1,3-phenylene diisocyanate, 4-chloro-1,3-phenylenediisocyanate,
4-bromo-1,3-phenylene diisocyanate, 4-ethoxy-1,3-phenylene-diisocyanate,
2,4'-diisocyanato-diphenylether, 5,6-dimethyl-1,3-phenylene diisocyanate,
2,4-dimethyl-1,3-phenylenediisocyanate, 4,4'-diisocyanatodiphenylether,
bis 5,6-(2-iso-cyanatoethyl)bicyclo [2,2,1]hept-2-ene,
benzidinediisocyanate, 4,6-dimethyl-1,3-phenylenediisocyanate,
9,10-anthracenediisocyanate, 4,4'-diisocyanatodibenzyl, 3,3-dimethyl-
4,4'-diisocyanatodiphenylmethane, 2,6-dimethyl-4,4'-diisocyanatodiphenyl
2,4-diisocyanatostilbene, 3,3'-dimethyl-4,4'-diisocyanatodiphenyl,
3,3'-dimethoxy-4,4'-diisocyanatodiphenyl 1,4-anthracenediisocyanate,
2,5-fluorenediisocyanate 1,8-naphthalenediisocyanate,
2,6-diisocyanatobenzfuran, 2,4,6-toluenetriisocyanate, and many other
organic polyisocyanates that are known in the art, such as those that are
disclosed in an article by Siefken, Ann., 565, 75 (1949). In general, the
aromatic polyisocyanates are preferred.
Particularly useful isocyanate components of high resilience cold cure
formulations within the scope of this invention are combinations of
isomeric tolylene diisocyanates and polymeric isocyanates having units of
the formula
##SPC1##
wherein R is hydrogen and/or lower alkyl and x has a value of at least 2.1.
Preferably the lower alkyl radical is methyl and x has a value of from 2.1
to about 3.0.
The amount of polyisocyanate employed will vary slightly depending on the
nature of the polyurethane being prepared. In general the polyisocyanates
are employed in the foam formulations of this invention in amounts that
provide from 80 to 150 per cent, preferably from 90 to 110 per cent of the
stoichiometric amount of the isocyanato groups required to react with all
of the hydroxyl groups of the organic polyol starting materials and with
any water present as a blowing agent. Most preferably, a slight amount of
isocyanato groups in excess to the stoichiometric amount is employed.
The blowing agents employed in this invention include methylene chloride,
water, liquefied gases which have boiling points below 80.degree.F. and
above -60.degree.F., or by other inert gases such as nitrogen, carbon
dioxide, methane, helium and argon. Suitable liquefied gases include
saturated aliphatic fluorohydrocarbons which vaporize at or below the
temperature of the foaming mass. Such gases are at least partially
fluorinated and can also be otherwise halogenated. Fluorocarbon blowing
agents suitable for use in foaming the formulations of this invention
include trichloromonofluoromethane, dichlorodifluoromethane,
dichlorofluoromethane, 1,1-chloro-1-fluoroethane, 1-chloro-1,1-difluoro,
2,2-dichloroethane, and 1,1,1-trifluoro, 2-chloro-2-fluoro,
3,3-difluoro-4,4,4-trifluorobutane. The amount of blowing agent used will
vary with density desired in the foamed product. Usually from 2 to 20
parts by weight of the blowing agent per 100 parts by weight of the
organic polyol starting materials are preferred.
The catalysts employed in this invention include any of the catalyst used
in producing conventional flexible polyurethane foam. Illustrative
catalysts are conventional amine catalysts such as N-methyl morpholine,
N-ethyl morpholine, hexadecyl dimethylamine, triethylamine,
N,N,N',N'-tetramethyl-1,3-butanediamine, N,N-di-methylethanol-amine,
bis(2-dimethylaminoethyl)ether, N,N,N',N'-tetramethyl ethylenediamine,
4,4'-methylene bis(2-chloroaniline), dimethyl benzylamine, N-coco
morpholine, triethylene diamine, [1,4-diazobicyclo (2,2,2)-octane], the
formate salts or triethylene diamine, other salts or triethylene diamine
and oxyalkylene adducts of primary and secondary amino groups, and the
like. If desired, conventional organo metal catalysts may be used to
supplement the amine catalysts. Illustrative of such metal catalysts are
the tin salts of various carboxylic acids e.g. stannous octoate, dibutyl
tin dilaurate, nickel acetylacetonates, and the like. Generally the total
amount of catalyst employed in the mixtures will range from 0.1 to 2
weight percent based on the total weight of the organic polyol starting
materials.
The relative amounts of the various components reacted in accordance with
the above described process for producing high resilience polyether
urethane foams in accordance with this invention are not narrowly
critical. The polyether and the polyisocyanate are present in the foam
formulations used to produce such foams, i.e. a major amount. The relative
amounts of these two components is the amount required to produce the
urethane structure of the foam and such relative amounts are well known in
the art. The blowing agent, catalyst and siloxanes are each present in a
minor amount necessary to achieve the function of the component. Thus, the
blowing agent is present in a minor amount sufficient to foam the reaction
mixture, the catalyst is present in a catalytic amount (i.e., an amount
sufficient to catalyze the reaction to produce the urethane at a
reasonable rate) and the siloxane fluids are present in a foam-stabilizing
amount (i.e., in an amount sufficient to stabilize the foam against voids
and shrinkage). Preferred amounts of these various components are given
hereinabove
The high resilience cold cure urethane foams produced in accordance with
this invention can be used for the same purposes as corresponding
conventional hot cure polyether urethane foams, e.g. they can be used
where ever cushioning is desired, e.g. in furniture; in transportation
systems, automobiles, planes, etc.; in carpeting; in the packaging of
delicate objects; and the like.
Other additional ingredients can be employed in minor amounts in producing
the high resilience polyether urethane foams in accordance with the
process of this invention, if desired, for specific purposes. Thus
inhibitors (e.g. d-tartaric acid and tertiary-butyl pyrocatechol, "Ionol")
can be employed to reduce any tendency of the foam to hydrolytic or
oxidative instability. Flame retardants (e.g.
tris(2-chloroethyl)phosphate) can be used. Dihydrocarbon silicone oils,
e.g. dimethylsiloxanes, the siloxane-oxyalkylene block copolymers
described in U.S. application No. 84,181 filed Oct. 26, 1970, now U.S.
Pat. No. 3,741,917 the aralkyl modified siloxanes described in U.S.
applicaton No. 305,713 filed Nov. 13, 1972 now U.S. Pat. No. 3,839,384 and
the cyanealkyl modified siloxane fluids described in my copending U.S.
application Ser. No. 325,327 filed Jan. 22, 1973, now abandoned may be
mixed if desired with the siloxanes employed in this invention. While such
mixtures are not required they may help expand the usefulness of the
siloxane fluids employed herein by increasing the adaptability of the
siloxane fluid to a variety of foam formulations. Of course any organic
solvent for the amine catalysts, e.g. polyols such as hexylene glycol
(i.e. 2-methyl-2,4-pentanediol), dipropylene glycol, and the like can be
used which substantially do not adversely effect the operation of the
process or reactants. Examples of other additives that can be employed are
crosslinkers such as glycerol, triethanol amine, and their oxyalkylene
adducts, and anti-yellowing agents.
An additional feature of the instant invention are the novel compositions
suitable for use in producing the high resilience polyether urethane foam.
For example it may be desirable, particularly on a commercial scale to
employ the cyanoalkoxy-alkyl modified siloxane fluid in a diluted form,
i.e. in the form of a siloxane fluid-solvent solution premix or a siloxane
fluid-solvent-catalyst solution premix. Such solution premixtures can help
serve to eliminate any mixing, metering, or settling problems. Moreover,
fewer streams of ingredients may be needed at the mixing head of the
operational apparatus. Of considerable importance is that the formulator
has the latitude to select the particular solvent which best suits the
system and minimize or eliminate any loss of foam properties. Siloxane
fluid-solvent-catalyst premixes can also be used since the selected
solvent can be one which serves the dual role of solvent for the catalysts
as well as the siloxane fluid. This option of formulating a premix
simplifies the foaming operation and improves the precision of metering
ingredients. While any suitable organic solvent such as hydrocarbon,
halohydrocarbons, organic hydroxyl compounds, alkyl phthalates, and the
like may be employed, preferably when employed the solvent selected should
be one in which the cyanoalkoxy-alkyl modified siloxane fluid is
substantially soluble. For example, it is preferred that at least five
parts by weight of the cyanoalkoxy-alkyl modified siloxane oil be soluble
in 95 parts by weight of solvent. More preferably the minimum percentage
of cyanoalkoxy-alkyl modified siloxane fluid in the siloxane fluid-solvent
or siloxane fluid-solvent-catalyst solutions should be in the range of at
least about ten to at least about 30 weight percent. Of course it is
understood that such solvents need not be employed and that the maximum
percentage of cyanoalkoxyalkyl modified siloxane fluid in said solvent
solutions is not critical. Moreover, when employed such solvent solutions
should of course be correlated to the amounts of active cyanoalkoxy-alkyl
modified siloxane fluid that may be employed per hundred parts by weight
of the organic polyol starting material as outlined above. The same
correlation should also be made with regard to catalyst when a siloxane
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