U.S. patent number [Application Number ] was granted by the patent office on 0000-00-00 for united states patent: re28715 ( 1.
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United States Patent |
RE28,715 |
|
**Please see images for:
( Certificate of Correction ) ** |
Issue Date: |
February 17,
1976 |
Current U.S.
Class: |
524/762; 521/137;
521/157; 521/172; 528/75; 521/156; 521/163; 528/76; 525/131 |
Current CPC
Class: |
C08F
291/08 (20130101); C08G 18/638 (20130101) |
Current International
Class: |
C08F
291/00 (20060101); C08F 291/08 (20060101); C08G
18/00 (20060101); C08G 18/63 (20060101); C08K
005/06 () |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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738,883 |
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Oct 1955 |
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UK |
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1,077,430 |
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Sep 1960 |
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DT |
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1,105,179 |
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Nov 1961 |
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DT |
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1,111,394 |
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Jul 1961 |
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DT |
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434,783 |
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Jun 1934 |
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UK |
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159,243 |
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Jun 1957 |
|
SW |
|
846,502 |
|
Aug 1960 |
|
UK |
|
796,294 |
|
Jun 1958 |
|
UK |
|
Primary Examiner: Wong, Jr.; Harry
Parent Case Text
This application is a continuation-in-part of application Ser. No.
155,467, filed Nov. 28, 1961, now abandoned, and of application
Ser. No. 256,531, filed Feb. 6, 1963, now U.S. Patent No.
3,304,273.
Claims
1. A method for preparing reactive compositions convertible to
elastic polyurethane products .[.by.]. comprising the steps of
(a) dispersing a minor amount of ethylenically unsaturated monomer
in a major amount of a solvent medium, said solvent medium
consisting essentially of at least one normally liquid polyol
essentially free from ethylenic unsaturation and having a molecular
weight of at least about 2,000 and a hydroxyl number in the range
of about 30 to about .[.140.]. .Iadd.600, said hydroxyl number
being appropriate to provide an elastic polyurethane,
.Iaddend.and
(b) polymerizing said monomer in said solvent by free radical
addition polymerization to a substantially linear polymer having a
molecular weight of at least 5,000 to provide a liquid, stable
dispersion of polymerpolyol having a viscosity of less than 40,000
cps at 10% polymer concentration.
said .Iadd.substantially linear .Iaddend.polymer being film-forming
and .Iadd.having radicals reactive with isocyanate radicals,
.Iaddend.said reactive composition being convertible to an elastic
polyurethane product upon reaction with an organic
polyisocyanate.
2. A method in accordance with claim 1 wherein said ethylenically
unsaturated monomer is free of reactive radicals containing active
hydrogen atoms.
3. A method in accordance with claim 1 wherein said monomer and
said polyol are selected to provide a polymer in said
polymer-polyol mixture containing radicals selected from the group
consisting of --COOH, --OH, --SH and organic nitrogen-containing
radicals in which all of the nitrogen bonds are satisfied by bonds
with at least one member selected from the group consisting of
carbon and hydrogen.
4. A method in accordance with claim 1 wherein said monomer is a
single species of ethylenically unsaturated monomer.
5. A method in accordance with claim 1 wherein said reactive
composition is produced by the in situ polymerization of a
plurality of ethylenically unsaturated monomers in said solvent
medium.
6. A method in accordance with claim 1 wherein said ethylenically
unsaturated monomer contains an organic nitrogen-containing radical
in which all of the nitrogen bonds are satisfied by bonds with at
least one member selected from the group consisting of carbon and
hydrogen.
7. A method as defined in claim 1 wherein said ethylenically
unsaturated monomer is selected from the group consisting of
acrylic acid, methacrylic acid, crotonic acid, itaconic acid,
2-hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl
acrylate, hydroxypropyl methacrylate, t-butylaminoethyl
methacrylate, dimethylaminoethyl methacrylate, glycidyl acrylate,
diglycol esters of itaconic acid, glycol monoesters of itaconic
acid, methyl monoester of itaconic acid, allyl alcohol, maleic
acid, fumaric acid, acrylamide and substituted acrylamide.
8. A method as defined in claim 1 wherein said film-forming polymer
is a copolymer resulting from the polymerization of at least two
ethylenically unsaturated monomers at least one of which contains
at least one radical reactive with the --N=C=O radical of an
isocyanate.
9. A method as defined in claim 8 wherein said ethylenically
unsaturated monomer which contains at least one radical reactive
with the --N=C=O radical of an isocyanate is selected from the
group consisting of acrylic acid, methacrylic acid, crotonic acid,
itaconic acid, 2-hydroxyethyl methacrylate, hydroxyethyl acrylate,
hydroxypropyl acrylate, hydroxypropyl methacrylate,
t-butylaminoethyl methacrylate, dimethylaminoethyl methacrylate,
glycidyl acrylate, diglycol esters of itaconic acid, glycol
monoesters of itaconic acid, methyl monoester of itaconic acid,
allyl alcohol, maleic acid, fumaric acid, acrylamide and
substituted acrylamide.
10. A reactive composition comprising the product of the in situ
polymerization of an ethylenically unsaturated monomer in a
reactive solvent having a plurality of radicals reactive with
isocyanato radicals produced in accordance with the method of claim
1.
11. A reactive composition as defined in claim 10 wherein said
ethylenically unsaturated monomer is free of reactive radicals
containing active hydrogen atoms.
12. A reactive composition as defined in claim 10 wherein the
polymeric product contains radicals selected from the group
consisting of --COOH, --OH, NH.sub.2, =NH, --SH, and
CONH.sub.2.
13. A reactive composition as defined in claim 10 wherein said
monomer is a single species of ethylenically unsaturated
monomer.
14. A reactive composition in accordance with claim 10 produced by
the in situ polymerization of a plurality of ethylenically
unsaturated monomers in said solvent.
15. A reactive composition as defined in claim 10 wherein said
monomer contains a radical reactive with isocyanato radicals.
16. A reactive composition in accordance with claim 10 produced by
the in situ polymerization of styrene in said solvent.
17. A reactive composition in accordance with claim 10 produced by
the in situ polymerization of styrene and acrylic ester in said
solvent.
18. A reactive composition in accordance with claim 10 produced by
the in situ polymerization of a lower alkyl methacrylate in said
solvent.
19. A reactive composition in accordance with claim 10 produced by
the in situ polymerization of a lower alkyl acrylate in said
solvent.
20. A reactive composition in accordance with claim 10 produced by
the in situ polymerization of a vinyl ester in said solvent.
21. A reactive composition in accordance with claim 10 produced by
the in situ polymerization of a vinyl ester and an acrylic ester in
said solvent.
22. A reactive composition in accordance with claim 10 produced by
the in situ polymerization of a polymerizable tertiary amine in
said solvent.
23. A composition in accordance with claim 10 comprising the in
situ polymerizate of a polymerizable ethylenically unsaturated
monomer in a polyether polyol. .Iadd. 24. A reactive composition as
defined in claim 10 in which the polymer concentration in the
composition (A) is from about 20% to about 50% by weight of said
composition. .Iaddend. .Iadd.25. A reactive composition as defined
in claim 10 in which the polyol is a polyoxypropylene
polyol..Iaddend. .Iadd.26. A reactive composition as defined in
claim 10 in which the polyol is a polyoxypropylene glycol..Iaddend.
.Iadd.27. A reactive composition as defined in claim 10 in which
the polyol is a polyoxypropylene triol..Iaddend. .Iadd.28. A
reactive composition as defined in claim 10 in which the polymer
has a molecular weight of at least 10,000..Iaddend. .Iadd.29. A
reactive composition as defined in claim 10 in which the
polymerization of the ethylenically unsaturated monomer in the
polyol is carried out in the presence of azobisbutyronitrile as a
catalyst..Iaddend..Iadd. 30. A reactive composition convertible to
an elastic polyurethane product having improved load bearing
properties by reaction with an organic polyisocyanate, said
reactive composition being produced by a method comprising the
steps of
(a) dispersing a minor amount of ethylenically unsaturated monomer
in a major amount of a solvent medium, said solvent medium
consisting essentially of at least one normally liquid
polyoxypropylene polyol essentially free from ethylenic
unsaturation and having a molecular weight of at least about 2,000
and a hydroxyl number in the range of about 30 to about 600, said
hydroxyl number being appropriate to provide an elastic
polyurethane, and
(b) polymerizing said monomer in said solvent by free radical
addition polymerization to a substantially linear polymer having a
molecular weight of at least 10,000 to provide a liquid, stable
dispersion of polymer polyol having a viscosity of less than 40,000
cps at 10% polymer concentration,
said substantially linear polymer being film-forming and having
radicals reactive with isocyanate radicals, said reactive
composition having a combining weight in the range providing an
elastic polyurethane product upon reaction with an organic
polyisocyanate. .Iaddend. .Iadd.31. A composition as claimed in
claim 30 in which the polymerization of the ethylenically
unsaturated monomer in the polyol is carried out in the presence of
azobisisobutyronitrile as a catalyst..Iaddend..Iadd. 32. A
composition as claimed in claim 30 in which the polymer
concentration in the composition is from about 20% to about 50% by
weight of said mixture.
Description
This invention relates to novel methods of preparing polyurethanes,
to reactive solutions therefor and to products produced by such
methods.
Polyurethanes constitute a broad class of polymeric materials
having a wide range of physical characteristics. The polymers are
produced through the interaction of a polyfunctional isocyanate
with a polyfunctional chemical compound having an active hydrogen
in its structure such as a polyester, polyesteramide or polyether
or mixtures of two or more of such materials. This component used
in preparing the polyurethane is generally termed by the art the
"active-hydrogen-containing material" and is generally liquid or a
solid capable of being melted at a relatively low temperature. The
materials conventionally used contain hydroxyl groups as the
radical having the active hydrogen and thus are generally termed
"polyol." The preparation of such materials is shown, for example,
in U.S. 2,888,409 and in the patents referred to therein. In
addition, other hydroxyl-capped polymers useful as the polyol in
preparing polyurethane resins include polyformals as described for
example in U.S. 3,055,871 to Heffler et al.; the
hydroxyl-terminated lactone polyesters described in U.S. 3,051,687
to Young et al.: the alkylene oxide adducts of the allyl alcohol
styrene polymers as described in U.S. 2,965,615 to Tass, et cetera.
For reasons of commercial availability and cost, it is conventional
to use polyethers having hydroxyl-terminated chains in the
preparation of polyurethane foams and either such polyethers or
hydroxyl-terminated polyesters in preparing vulcanizable gum,
adhesives, films, et cetera. The polyurethane end products are
generally cross-linked to some extent by including with the polyol
(which is generally difunctional) a small amount of a
polyfunctional cross-linking agent.
Despite the variety of physical and chemical properties obtainable
by proper selection of the polyisocyanate and the polyol, as well
as the conditions under which the reaction is carried out, there
are definite limitations in selecting components for desirable
properties in the resulting resin. One of the most significant of
such limitations arises from the fact that the polyol is generally
of relatively low molecular weight arising from the fact that it
must be sufficiently liquid to permit mixing and reaction with the
polyfunctional polyisocyanate in producing the final polyurethane
resin. Further, the use of higher molecular weight components is
attended by a variety of other difficulties including handling and
compounding problems, the use of inert solvents and the problems
attendant thereon as solvent removal, shrinkage, et cetera.
A great deal of art has grown up reflecting the extensive efforts
made to incorporate higher molecular weight resinous material in
polyurethane formulations. Such efforts range from mere mechanical
mixtures as described, for example, in U.S. 3,049,505 to Grabowski,
to such other means as the addition of a polymer latex as described
in U.S. 2,993,013 to Wolfe, wherein an aqueous elastomer latex is
added as one component to an isocyanate-terminated polyurethane so
that the water phase of the latex reacts with the free isocyanate
groups and at the same time the elastomer of the latex is
incorporated into the resulting polyurethane.
Another means shown by the art is in U.S. 2,693,838 to Simon et
al., wherein a small amount of the desired polymer is dissolved in
a large excess of the polyfunctional isocyanate. Where the polymer
is inert to the isocyanate, it is merely mechanically incorporated
into the resulting polyurethane while, where a reaction occurs, the
reactive radicals in the polymer itself may enter into a reaction
with the polyisocyanate before it can be compounded with additional
ingredients.
Still another means shown by the art is in U.S. 3,008,917 to Park
et al., wherein an unsaturated liquid monomer such as styrene is
added to a polyester-isocyanate adduct which itself contains vinyl
unsaturation (as by utilizing a polyester prepared from maleic
anhydride or similar unsaturated acid). The resulting mixture is
then copolymerized through the unsaturated linkages.
Yet another method is shown in U.S. 2,882,260 to Bartl et al. In
this process an isocyanate is attached to an ethylenically
unsaturated compound, the isocyanate group is then blocked to
render it non-reactive and the resulting compound is copolymerized
as with styrene or a similar monomer in aqueous emulsion or similar
process and the resulting polymeric product is dried and then
heated to unblock the isocyanate groups and cause
cross-linkage.
Despite the variety and ingenuity displayed by such art,
polyurethanes still remain greatly limited in practical methods for
the inclusion of higher molecular weight polymers therein.
Accordingly, it is a primary purpose of the present invention to
present novel methods of forming polyurethanes which employ high
molecular weight film-forming polymers in the polyurethane
reaction.
Another object of the invention is to incorporate high molecular
weight film-forming polymers as one of the reactants in forming
polyurethanes whereby the film-forming polymers are chemically
incorporated in the resulting polyurethane.
A further object of the invention is to incorporate high molecular
weight film-forming polymers in polyurethane resins without
complicated or cumbersome processing techniques.
It is another principal object of the present invention to provide
a novel method of forming polyurethanes utilizing high molecular
weight film-forming polymers as one of the components in the
polyurethane reaction.
It is still a further object of the present invention to produce
film-forming polymers having radicals reactive with the isocyanate
radical in a solvent medium also having radicals reactive with said
isocyanato radical.
Another object of the present invention is to provide a process for
the production of polyurethanes which is carried out with liquid
reactants, including a polyfunctional isocyanate and a high
molecular weight film-forming polymer in a medium reactive with the
isocyanato radical, which involves a minimum of handling and
compounding problems, and which results in negligible shrinkage of
the polyurethane reaction product.
Another object of the present invention is to provide novel and
improved polyurethanes resulting from the novel processes of the
instant application.
These and other objects and advantages of the present invention
will become more apparent upon reference to the following detailed
description and appended claims.
In essence, the invention of the instant application comprises a
method for preparing reactive compositions comprising the steps
of
(a) Dispersing a minor amount of ethylenically unsaturated monomer
in a major amount of a solvent medium, said solvent medium
consisting essentially of at least one normally liquid polyol
essentially free from ethylenic unsaturation and having a molecular
weight of at least about 500 and a hydroxyl number in the range of
about 30 to about 600, and
(b) Polymerizing said monomer in said solvent by free radical
addition polymerization to a substantially linear polymer having a
molecular weight of at least 5,000 to provide a liquid, stable
dispersion of polymer-polyol having a viscosity of less than 40,000
cps. at 10% polymer concentration.
The reactive compositions of the present invention have two
essential components: a high molecular weight film-forming polymer
having radicals reactive with isocyanato radicals and a reactive
solvent which is a solvent or dispersing medium for said polymer
and which contains radicals reactive with isocyanato radicals. This
will be more fully explained hereinafter. Upon addition of the
polyisocyanate to the reactive compositions of the invention, the
film-forming polymer and the reactive solvent both enter into a
chemical reaction with the isocyanato groups and are chemically and
integrally bound in the resulting polyurethane.
In accordance with the present invention, the reactive
radical-containing polymers are formed in situ in the reactive
solvent by adding monomers or low molecular weight oligomers to the
olvent and effecting polymerization therein. Such polymers can be
formed from ethylenically unsaturated monomers containing at least
one polymerizable >C.dbd.C< group. The reactive solvent must,
of course, be compatible in each instance with the system involved.
It is only necessary that the film-forming polymer so produced be
reactive with isocyanato groups and form a stable solution or
dispersion in the reactive solvent.
The preferred reactive radical (i.e. reactive with the isocyanato
group) is an active hydrogen [the term "active hydrogen" refers to
hydrogen atoms, which, because of their position in the molecule
display activity according to the Zerewitinoff test as described by
Wohler in the Journal of the American Chemical Society, vol. 49,
page 3181 (1927)]. Illustrative of some of the reactive radicals
containing active hydrogen are --COOH, --OH, --NH.sub.2, .dbd.NH,
--CONH.sub.2, substituted ammonias such as quaternary ammonium,
mercapto compounds, et cetera.
Compounds containing the .dbd.N group, such as N-vinyl pyrrolidone,
methacrylonitrile, dimethylaminomethyl methacrylate and vinyl
pyridine, do not give a positive Zerewitinoff test but they do
polymerize in reactive solvents to produce reactive compositions
containing the film-forming polymers in the reactive solvent, said
compositions containing film-forming polymer having a minor amount
of reactive radicals introduced into the polymer during the
polymerization reaction from the polymerization medium. This
probably occurs, by chain transfer with graft or block formation.
These reactive compositions are useful in the production of
polyurethanes having outstanding properties.
As previously indicated, the reactive compositions of this
invention are produced by the in situ polymerization of a
polymerizable ethylenically unsaturated monomer in a reactive
solvent medium. During this polymerization a minor amount of graft
or block polymer is inherently produced. Thus, regardless of
whether or not the ethylenically unsaturated monomer itself
contains radicals reactive with the isocyanato group, the reactive
compositions produced always contain film-forming polymer having
radicals reactive with the isocyanato group. Among ethylenically
unsautrated monomers which do not have a radical reactive with the
isocyanato group are styrene, methyl methacrylate and vinyl
acetate; however, all of these produce, after polymerization,
reactive compositions that contain film-forming polymer having a
minor amount of reactive radicals introduced from the
polymerization medium and the reactive compositions react with the
isocyanato group.
The reactive compositions are produced by polymerizing the monomers
in the selected reactive solvent at a temperature of from about
40.degree. C. to 150.degree. C. in the presence of a catalytically
effective amount of a conventional free radical catalyst known to
be suitable for the polymerization of ethylenically unsaturated
monomers. The concentration of the catalyst can vary from about
0.001 to about 5 percent, preferably from about 0.2 to about 0.5
percent; however, any effective catalytic amount is satisfactory.
Illustrative catalysts are the well-known free radical type of
vinyl polymerization catalysts, for example, the peroxides,
persulfates, perborates, percarbonates, azo compounds, etc.,
including hydrogen peroxide, dibenzoyl peroxide, acetyl peroxide,
benzoyl hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide,
lauroyl peroxide, butyryl peroxide, diisopropylbenzene
hydroperoxide, cumene hydroperoxide, paramenthane hydroperoxide,
diacetyl peroxide, di-alpha-cumyl peroxide, dipropyl peroxide,
diisopropyl peroxide, isopropyl-t-butyl peroxide, butyl-t-butyl
peroxide, dilauroyl peroxide, difuroyl peroxide, ditriphenylmethyl
peroxide, bis(p-methoxybenzoyl)peroxide, p-monomethoxybenzoyl
peroxide, rubrene peroxide, ascaridol, t-butyl peroxybenzoate,
diethyl peroxyterephthalate, propyl hydroperoxide, isopropyl
hydroperoxide, n-butyl hydroperoxide, t-butyl hydroperoxide,
cyclohexyl hydroperoxide, trans-Decalin hydroperoxide,
alpha-methylbenzyl hydroperoxide, alpha-methyl-alpha-ethyl benzyl
hydroperoxide, Tetralin hydroperoxide, triphenylmethyl
hydroperoxide, diphenylmethyl hydroperoxide,
alpha,alpha'-azo-2-methyl butyronitrile, alpha,alpha'-2-methyl
heptonitrile, 1,1'-azo-1-cyclohexane carbonitrile, dimethyl
alpha,alpha'-azo-isobutyrate, 4,4'-azo-4-cyanopentanoic acid,
azobisisobutyronitrile, persuccinic acid, diisopropyl peroxy
dicarbonate, and the like; a mixture of catalysts may also be
used.
The polymerization can also be carried out with an inert organic
solvent present. Illustrative thereof are toluene, benzene,
acetonitrile, ethyl acetate, hexane, heptane, dicyclohexane,
dioxane, acetone. N,N-dimethylformamide, N,N-dimethylacetamide, and
the like, including those known in the art as being suitable
solvents for the polymerization of vinyl monomers. The only
requirement in the selection of the inert solvent and the reactive
solvent is that they do not interfere with the monomer's
polymerization reaction. When an inert organic solvent is used, it
is preferably removed by conventional means.
The monomers useful in the process of this invention are the
polymerizable monomers characterized by the presence therein of at
least one polymerizable ethylenic unsaturated group of the type
C.dbd.C. The monomers can be used singly or in combination to
produce homopolymer/reactive solvent or copolymer/reactive solvent
reactive compositions.
These monomers are well known in the art and include the
hydrocarbon monomers such as butadiene, isoprene, 1,4-pentadiene,
1,6-hexadiene, 1,7-octadiene, styrene, alpha - methylstyrene,
methylstyrene, 2,4-dimethylstyrene, ethylstyrene, isopropylstyrene,
butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, and
the like, substituted styrenes such as chlorostyrene,
2,5-dichlorostyrene, bromostyrene, fluorostyrene,
trifluoromethylstyrene, iodostyrene, cyanostyrene, nitrostyrene.
N,N-dimethylaminostyrene, acetoxystyrene, methyl 4-vinylbenzoate,
phenoxystyrene, p-vinyl diphenyl sulfide, p-vinylphenyl phenyl
oxide, and the like; the acrylic and substituted acrylic monomers
such as acrylic acid, methacrylic acid, methylacrylate,
2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, methyl
methacrylate, cyclohexyl methacrylate, benzyl methacrylate,
isopropyl methacrylate, octyl methacrylate, methacrylonitrile,
methyl alpha-chloroacrylate, ethyl alpha-ethoxyacrylate, methyl
alpha-acetaminoacrylate, butyl acrylate, 2-ethylhexyl acrylate,
phenyl acrylate, phenyl methacrylate, alpha-chloroacrylonitrile,
N,N - dimethylacrylamide, N,N - dibenzylacrylamide,
N-butylacrylamide, methacrylyl formamide, and the like; the vinyl
esters, vinyl ethers, vinyl ketones, etc. such as vinyl acetate,
vinyl chloroacetate, vinyl alcohol, vinyl butyrate, isopropenyl
acetate, vinyl formate, vinyl acrylate, vinyl methacrylate, vinyl
methoxy acetate, vinyl benzoate, vinyl iodide, vinyl toluene, vinyl
naphthalene, vinyl bromide, vinyl fluoride, vinylidene bromide,
1-chloro-1-fluoroethylene, vinylidene fluoride, vinyl methyl ether,
vinyl ethyl ether, vinyl propyl ethers, vinyl butyl ethers, vinyl
2-ethylhexyl ether, vinyl phenyl ether, vinyl 2-methoxyethyl ether,
methoxybutadiene, vinyl 2-butoxyethyl ether, 3,4-dihydro-1,2-pyran,
2-butoxy-2'-vinyloxy diethyl ether, vinyl 2-ethylmercaptoethyl
ether, vinyl methyl ketone, vinyl ethyl ketone, vinyl phenyl
ketone, vinyl ethyl sulfide, vinyl ethyl sulfone, N-methyl-N-vinyl
acetamide, N-vinylpyrrolidone, vinyl imidazole, divinyl sulfide,
divinyl sulfoxide, divinyl sulfone, sodium vinyl sulfonate, methyl
vinyl sulfonate, 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,
dichlorobutadiene, vinyl pyridine, and the like. Any of the known
polymerizable monomers can be used and the compounds listed above
are illustrative and not restrictive of the monomers suitable for
use in this invention. Any of the known chain transfer agents can
be present if desired.
When the polymerization is carried out in the polyol, and the like
reactive radical-containing medium, it has been found that
interaction occurs to some degree between the solvent and the
polymer chain being formed whereby a graft or block copolymer is
inherently produced wherein the solvent molecule provides reactive
radicals to the block or graft copolymer. It is known in the art
that free radical producing inhibitors or catalysts are used for
carrying out the polymerization reaction. These produce active
sites initiating the formation of block or graft polymers which are
probably formed by chain transfer mechanisms in vinyl addition
polymerization. In this manner polymers inherently containing
reactive groups are prepared from ethylenically unsaturated
monomers which contain no reactive groups, provided that the
polymers are prepared by polymerization in a solvent containing
reactive groups, such as active hydrogen. The reactive solvent used
in the polymerization can also act as a chain transfer agent and
enter into the polymer chain. By the method of this invention,
therefore, reactive radicals can be introduced into polymer chains
by proper selection of the reactive solvent used as the medium for
the polymerization. These polymers can then be used for the
production of polyurethanes with outstanding properties.
The distribution of reactive radicals in the film-forming polymers
is, of course, not limited to terminal positions. On the contrary,
such radicals may be at various positions throughout the entire
polymer chain. It is generally advantageous, however, to use as one
of the monomers a material which itself contains a reactive
hydrogen group, thus allowing a much wider range of frequency of
reactive radicals.
The type of nitrogen bond formed in the reaction of the
polyisocyanate and the film-forming polymer will vary depending on
the chemical nature of the reactive composition. The chemistry of
formation and significance of the type of bonding are known in the
art.
If the polymer contains certain types of nitrogen radicals, such as
amino or amido radicals, it will also act as a catalyst for the
polyurethane formation. Where the reactive radical is carboxyl, it
may be desirable to modify the structure of the film-forming
polymer for certain purposes. More specifically, it is well known
that the reaction product of the --COOH and --N.dbd.C.dbd.O
radicals is an amide plus CO.sub.2. This reaction is desirable for
foam production but is frequently undesirable when porosity in the
finished product is to be avoided. It is a feature of the present
invention to avoid porous production formations in such a situation
by reacting a salt-forming nitrogen derivative with the carboxyls
of the film-forming polymer so as to change the reaction mechanism
of the components. (See, for example, applicant's co-pending
application Ser. No. 117,488, filed May 12, 1961.) For example, a
primary or secondary amine may be introduced, which will result in
the formation of a urea linkage with the --N.dbd.C.dbd.O radical.
Similarly, amino alcohols may be introduced, in which case the
hydroxyl group will react with the --N.dbd.C.dbd. O to form
urethane linkages. In these cases, a non-porous film or mass can be
obtained with the substituted --COOH radical. The --COOH radical
can also be reacted with a polyamine containing at least two free
primary amino groups. The available primary amino groups may then
be reacted with phosgene to form isocyanato groups so that the
material thus obtained would be an isocyanato-containing
prepolymer.
The combining weight of the polymer (with respect to the
polyisocyanate with which it is to be reacted) will play a
significant part in the properties of the polyurethane reaction
product since the frequency of the reactive radicals will determine
the location and also the number of bonds formed in the reaction
between the polymers and the polyisocyanate. More specifically, in
order to obtain the most highly useful product following the
isocyanate reaction, the reactive film-forming polymer should
contain a minimum number of reactive radicals such that the
combining weight of the polymer is not too high, viz., preferably
below 4000. Although in certain cases higher combining weights also
give good products, generally speaking, the higher the combining
weight, the softer, more elastic the reaction product; the lower
the combining weight, the more rigid the reaction product will be,
using the same major components in the product.
The optimum combining weight for a given reactive polymer (to
produce an end product having the most desirable properties) may be
determined by simple experimentation. The combining weight of a
given polymer reflects both the particular monomers used in the
formation of the polymer as well as the mol ratios of such
monomers. Since at least some of the groups of the polymer or
copolymer which are reactive with the isocyanato group are those
present in the molecule of the reactive solvent in the polymer, the
number of bonds formed in the reaction between the polymer and the
polyisocyanate cannot be easily predicted in advance. However, the
optimum concentration for any particular property can be determined
by normal routine experimentation.
The film-forming polymers are present as dispersions or solutions
in a reactive solvent and the reactive solutions or dispersions
formed from said polymers are often dilutable with a reactive
solvent. Where the solution or dispersion is not dilutable, the
polymer should be prepared in the solvent at the concentration
desired for the ultimate use so that dilution is unnecessary.
The molecular weight of the film-forming polymers of the present
invention will necessarily vary within reasonably wide limits
depending upon the particular polymer formed. The molecular weight
is only a tough indication of whether a polymer is a film-former.
The film-forming ability of a polymer is determined primarily by
its cohesive energy. Conventionally a polymer is considered to be a
film-forming polymer when the cohesion in the polymer itself is
great enough to produce a film above the "glass" temperature, i.e.,
above the second order transition temperature. In general, the
film-forming polymers used have a molecular weight above 5000, best
properties being obtained with film-forming polymers having
molecular weights of 10,000 or greater. The upper molecular weight
limit is one selected for practical considerations; the reactive
compositions are preferably those which are free flowing at the
temperature at which reaction with the polyisocyanate is carried
out, i.e., the composition should have a viscosity at that
temperature of less than about 40,000 cps. If the reactive polymer
has sufficient reactive radicals to cross-link adequately with the
isocyanate, the restriction that the polymer be film-forming may be
somewhat relaxed.
As is evident from the list of monomers which may be used to form
the film-forming polymers of the present invention, film-forming
polymers having either aromatic or aliphatic nucleii (or both) may
be employed. The choice of the particular nucleus is dependent upon
the final properties desired in the polyurethane. For example,
film-forming polymers having predominantly aromatic nucleii will
tend to produce stiffer products; those with predominantly
aliphatic nucleii will tend to produce softer products. In general,
the physical properties of the polymer will reflect in the
polyurethanes.
The second essential component of the reactive composition of the
present invention is a reactive solvent. The "reactive solvent"
used herein is the "active-hydrogen-containing material" known in
the art and conventionally used in preparing polyurethane
resins.
The reactive solvent must be selected to meet several diverse
requirements:
(1) It must act as a solvent or dispersing medium for the
film-forming polymer.
(2) It must not be so reactive with the film-forming polymer as to
reduce substantially the reactive radical content of either the
solvent or the polymer or to form a gel or a hard infusible resin
which would interfere or even prevent the reaction with the
polyisocyanate.
(3) It should form stable solutions or dispersions with the
film-forming polymer which are preferably dilutable without the
formation of undesirable precipitates with the components used to
form the polyurethane polymer.
(4) It must be a liquid, at least at the temperature used for the
reaction with the polyisocyanate.
(5) It must have at least two radicals which are reactive with the
--N.dbd.C.dbd.O of the polyisocyanates so as to form a polymeric
reaction product with the polyisocyanate.
The preferred reactive solvents are the polyols having properties
described above. The polyols suitable for production of the
reactive compositions can be a hydroxyl-terminated polyester, a
polyhydroxyalkane, a polyphenol, a polyoxyalkylene polyol, or the
like, having a molecular weight of about 500 and the corresponding
mercapto derivatives. Among the polyols which can be employed are
one or more polyols from the following classes of compositions;
minor amounts of polyhydroxyalkanes can be present:
(a) Hydroxyl-terminated polyesters;
(b) Alkylene oxide of polyhydroxyalkanes;
(c) Trialkanolamines and alkylene oxide adducts thereof;
(d) Alcohols derived from mono- and polyamines by addition of
alkylene oxides;
(e) Non-reducing sugars and sugar derivatives and alkylene oxide
adducts thereof;
(f) Alkylene oxide adducts of aromatic amine/phenol/aldehyde
condensation products;
(g) Alkylene oxide adducts of phosphorus and polyphosphorus
acids;
(h) Polyphenols and alkylene oxide adducts thereof;
(i) Polytetramethylene glycols, and the like.
Illustrative hydroxyl-terminated polyesters are those which are
prepared by polymerizing a lactone in the presence of an active
hydrogen-containing starter as disclosed in U.S. Pat. No.
2,914,556.
Illustrative alkylene oxide adducts of polyhydroxyalkanes include
among others, those adducts of ethylene glycol, propylene glycol,
1,3-dihydroxypropane, 1,3-dihydroxybutane, 1,4-dihydroxybutane,
1,4-, 1,5-, and 1,6-dihydroxyhexane, 1,2-, 1,3-, 1,4-, 1,6-, and
1,8-dihydroxyoctane, 1,10-dihydroxydecane, glycerol,
1,2,4-trihydroxybutane, 1,2,6-trihydroxyhexane,
1,1,1-trimethylolethane, 1,1,1-trimethlolpropane, pentaerythritol,
xylitol, arabitol, sorbitol, mannitol, and the like, having a
molecular weight of at least 500: preferably the adducts of
ethylene oxide, propylene oxide, epoxybutane, or mixtures
thereof.
Two particularly preferred clasees of alkylene oxide adducts of
polyhydroxyalkanes are the ethylene oxide, propylene oxide,
butylene oxide, or mixtures thereof, adducts of dihydroxyalkanes
and of trihydroxyalkanes.
The preferred class of alkylene oxide adducts of dihydroxyalkanes
contemplated are the polyoxyalkylene glycols, such as the alkylene
oxide adducts of diethylene glycol, triethylene glycol,
tetraethylene glycol, dipropylene glycol, tripropylene glycol,
tetrapropylene glycol, dibutylene glycol, as well as the high
molecular weight polyoxyethylene glycols, high molecular weight
polyoxypropylene glycols, mixed ethylene-propylene glycols, mixed
polyoxyethylene-polyoxypropylene glycols, and the like.
Further examples of suitable polyesters and polyethers for use as
the polyol of the present invention are described in U.S. Patents
2,814,606; 2,801,990; 2,801,618; 2,777,831; 2,606,162 and
2,432,148. The patents also teach the method of preparing such
polyols. .Iadd.Said U.S. Pat. 2,801,990 describes polyesters and
polyesteramides at columns 8 and 9 having hydroxyl numbers from 30
or 40 to 100 or 140. .Iaddend.
Another useful class of polyols which can be employed are the
trialkanolamines which, by reaction with alkalene oxides, form
adducts of suitable molecular weight, and the alkylene oxide
adducts thereof. Illustrative of the lower molecular weight
trialkanolamines includes triethanolamine, triisopropanolamine, and
tributanaolamine. The alkylene oxide adducts which can be employed
are preferably those wherein the oxyalkylene moieties thereof have
from 2 to 4 carbon atoms.
Another useful class of polyols which can be employed are the
alkylene oxide adducts of mono- and polyamines.
The mono- and polyamines are preferably reacted with alkylene
oxides which have 2 to 4 carbon atoms, for example, ethylene oxide,
1,2-epoxypropane, the epoxybutanes, and mixtures thereof. Mono- and
polyamines suitable for reaction with alkylene oxides include,
among others, methylamine, ethylamine, isopropylamine, butylamine,
benzylamine, aniline, the toluidines, naphthylamines,
ethylenediamine, diethylenetriamine, triethylenetetramine,
1,3-butanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,2-,
1,3-, 1,4-, 1,5-, and 1,6-hexanediamine, phenylenediamines,
toluenediamine, naphthalenediamines, and the like. Among the
compounds of the above groups which are of particular interest are,
among others, N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine,
N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine,
N,N,N',N",N'"-pentakis(2-hydroxypropyl)diethylenetriamine,
phenyldiisopropanolamine and higher alkylene oxide adducts of
aniline, and the like. Others which deserve particular mention are
the alkylene oxide adducts of aniline or substituted
aniline/formaldehyde condensation products.
A further class of polyols which can be employed are the
non-reducing sugars, the non-reducing sugar derivatives, and more
preferably, the alkylene oxide adducts thereof wherein the alkylene
oxides have from 2 to 4 carbon atoms. Among the non reducing sugar
and sugar derivatives contemplated are sucrose, alkyl glycosides
such as methyl glucoside, ethyl glucoside, and the like, glycol
glycosides such as ethylene glycol glucoside, propylene glycol
glucoside, glycerol glucoside, 1,2,6-hexanetriol glucoside, and the
like.
A still further useful class of alcohols are the polyphenols, and
preferably the alkylene oxide adducts thereof wherein the alkylene
oxides have from 2 to 4 carbon atoms. Among the polyphenols which
are contemplated are found, for example, bisphenol A, bishphenol F,
condensation products of phenol and formaldehyde, more particularly
the novolac resins, condensation products of various phenolic
compounds and acrolein, the simplest members of this class being
the 1,1,3-tris(hydroxyphenyl)propanes, condensation products of
various phenolic compounds and glyoxal, glutaraldehyde, and other
dialdehydes, the simplest members of this class being the
1,1,2,2-tetrakis(hydroxyphenyl)ethanes, and the like.
Another desirable class of polyols are the alkylene oxide adducts,
preferably the ethylene oxide, 1,2-epoxypropane, epoxybutane, and
mixtures thereof, adducts of aromatic amine/phenol/aldehyde
condensation products. The condensation products are prepared by
condensing an aromatic amine, for instance aniline, toluidine, or
the like, a phenol such as phenol, cresol, or the like and an
aldehyde, preferably formaldehyde, at elevated temperatures in the
range of, for example, from 60.degree. C. to 180.degree. C. The
condensation product is then recovered and reacted with alkylene
oxide, using a basic catalyst (e.g., potassium hydroxide) if
desired, to produce the polyols. The propylene oxide and mixed
propylene-ethylene oxide adducts of aniline/phenol/formaldehyde
condensation products deserve particular mention.
The alkylene oxide adducts of phosphorus and polyphosphorus acids
are another useful class of polyols. Ethylene oxide,
1,2-epoxypropane, the epoxybutanes, 3-chloro-1,2-epoxypropane, and
the like are preferred alkylene oxides. Phosphoric acid, phosphorus
acid, the polyphosphoric acids such as tripolyphosphoric acid, the
polymethaphorphoric acids, and the like are desirable for use in
this connection.
Another useful class of polyols are the polytetramethylene glycols,
which are prepared by polymerizing tetrahydrofuran in the presence
of an acidic catalyst.
The polyols employed can have hydroxyl numbers which vary over a
wide range. In general, the hydroxyl numbers of the polyols
employed in the invention can range from about 20, and lower, to
about 1000, and higher, preferably, from about 30 to about 600, and
more preferably, from about 35 to about 450. The hydroxyl number is
defined as the number of milligrams of potassium hydroxide required
for the complete hydrolysis of the fully acetylated derivative
prepared from 1 gram of polyol. The hydroxyl number can also be
defined by the equation: ##EQU1## where OH=hydroxyl number of the
polyol
f=functionality, that is, average number of hydroxyl groups per
molecule of polyol
M.w.=molecular weight of the polyol.
The exact polyol employed depends upon the end use of the
polyurethane product to be produced. For example, in the case of
foamed reaction products, the molecular weight of the hydroxyl
number is selected properly to result in flexible, semiflexible, or
rigid foams. The above polyols preferably possess a hydroxy number
of from about 200 to about 1000 when employed in rigid foam
formulations, from about 50 to about 150 for semiflexible foams,
and from about 40 to about 70 or more when employed in flexible
foam formulations. Such limits are not intended to be restrictive,
but are merely illustrative of the large number of possible
combinations of the above polyol coreactants.
The reactive composition (comprising the film-forming polymer in
the reactive solvent) contains from 5 to 50 percent by weight of
the polymer therein; a preferable concentration is about 20 to 50
percent by weight. Solutions having in excess of 50 percent by
weight of the film-forming polymer are ordinarily too viscous for
practical purposes.
The isocyanates used to form the polyurethanes of the present
invention must be polyfunctional. Examples of such polyisocyanates
are the tolylene diisocyanates, hexamethylene diisocyanates,
diphenylmethane diisocyanates, naphthalene diisocyanates,
triphenylmethane triisocyanates, phenylene diisocyanates,
bitalylene diisocyanates, dianisidine diisocyanate,
dimethyldiphenylmethane diisocyanates, triisocyanatodiphenyl
ethers, et cetera, such as meta-toluene diisocyanate, 4,4'-diphenyl
diisocyanate, 4,4'-diphenylene methane diisocyanate,
1,5-naphthalene diisocyanate, 4,4'-diphenyl ether diisocyanate,
p-phenylene diisocyanate, ethylene diisocyanate, trimethylene
diisocyanate, cyclohexylene diisocyanate, 2-chloropropane
diisocyanate, tetrachlorophenylene diisocyanate-1,4, durylene
diisocyanate, xylylene diisocyanates,
3,10-diisocyanatotricyclo[5.2.1.0.sup.-.sup.6 ]decane, et cetera. A
more complete list of polyisocyanates is set forth by Siefken in
Annalen, 562, pp. 122-135 (1949).
The polyisocyanates react both with the film-forming polymer and
the reactive solvent so that the polyurethanes formed using the
reactive solutions of the instant invention incorporate both of
these materials into the chemical structure of the polyurethane.
Thus the resulting polyurethanes constitute a novel group of
polymers having substantially different properties than could be
obtained by a mere mechanical mixture. The new film-forming
polymers have significantly different properties from the polymer
formed by the same monomer or monomers polymerized under conditions
such that the reactive solvent molecules are not incorporated into
the polymer chain. In the polyurethane formation, the new reactive
composition containing the film-forming polymer has significantly
different properties compared with other systems in which the
preformed polymers have been dispersed in a reactive solvent. The
reaction rate for polyurethane formation is similar for the
radicals of solvent molecules attached to the polymer and for the
solvent itself. A more uniform polyurethane is thus formed. The
polyurethanes produced using such reactive solutions contain bonds
formed by the reaction of the polyisocyanate and the separate
reactive groups of the film-forming polymer and the reactive
solvent, and direct chemical bonds between the polymer and the
solvent. Thus, such polyurethanes comprise a variety of chemical
bonds with consequent effect on the physical and chemical
properties of the polyurethanes.
The reactive compositions produced are stable dispersions. However,
in the majority of cases, stable dispersions could not be obtained
when preformed polymer produced from the same monomer by
conventional processes was mixed with the same reactive
solvent.
The reactive compositions of the present invention may be used in
place of the polyols of the prior art in any of the processes used
in preparing polyurethanes. Thus, the compositions may be used in
the prepolymer process, the quasi-prepolymer process or the
one-shot process. The polyurethanes may be further reacted with
epoxy resins, cured with sulfur, peroxides or other curing agents,
or otherwise reacted or modified as known to those skilled in the
art. In using the one-shot process, as described for example in
U.S. 2,866,774 to Price, it is desirable to use a silicone oil
emulsifier as described in United States 2,834,748 and
2,917,480.
To form the polymethanes of the present invention, an excess of the
polyisocyanate is generally employed. In general, the ratio between
the --N=C=O radicals and the other reactive radicals in the
reactant mass (including those in the film-forming polymer, the
polyol and the other non-isocyanate reactants, if any) is from
about 1:1 to 5:1 and, in exceptional cases, up to 6:1.
As aforestated, the viscosity of the reactive composition
(comprising the film-forming polymer and the polyol in the ratio
desired) generally should be less than about 40,000 cps. under
conditions of use. Generally speaking, the viscosity of the
reactive composition should be such that the solution is dilutable
upon simple mixing with additional quantities of polyfunctional
liquid reactants used. The viscosity of the reactive composition
should also be low enough to permit easy mixing of the isocyanates
with the reactive solution. The term "composition" as used herein
in the specification and claims includes both optically clear or
turbid solutions or dispersions of solvated film-forming polymer in
which there is a marked viscosity increase or wherein the polymer
does not separate from solution on storage or during conventional
handling.
In carrying out the process of the present invention, the reactive
composition is first prepared and then mixed with the
polyisocyanate and any other reactants desired. For example, it may
be desired to vary the quantity of reactive, non-isocyanate
radicals in the reactant mass by adding other active
hydrogen-containing compounds.
Because of the great many variables involved in the process of the
present invention, i.e., the desired properties of the finished
product, the combining weight of the reactants, the type of
bonding, the solubility requirements (including the possibility
that certain materials will cause an undesirable precipitate to
form in the reactive solution), the selection of particular
film-forming polymers, solvents and other additives to be employed
in the reaction must, in good part, be done on an experimental
basis. The complete flexibility of the instant process, however,
makes possible the easy adjustment of the reactant mass to conform
it to one having desired characteristics.
This invention is further illustrated by the following examples
without, however, being restricted thereto. All parts are by
weight, unless otherwise specified. Unless otherwise stated in the
examples, the polymerization reactions were carried out in a
three-necked flask equipped with an agitator, a reflux condenser, a
thermometer, the three-necked flask being connected to a nitrogen
cylinder. Prior to the addition of the catalyst, the contents of
the flask were purged with nitrogen for 30 minutes and heated.
After completion of the reaction, toluol was added and the traces
of water remaining in the flask were removed by azeotropic
distillation. The reaction was carried out to an unreacted monomer
content of 5 percent maximum.
Example 1
The flask was charged with 220 g. styrene of 99% purity inhibited
with 0.02% of 5-butylcatechol. 125 g. 2-ethylhexyl acrylate of 99%
purity inhibited with 0.05% hydroquinone and 400 g. of Pluracol
P2010 (a polypropylene ether diol terminated with two hydroxy
radicals, having a molecular weight of 2000 and combining weight of
1000 and made by the Wyandotte Chemical Co.). After raising the
temperature of the flask to 70.degree. C., 11/2 g. of
azobisisobutyronitrile catalyst were added. The polymerization
reaction was then carried out at 130.degree. C. for 3 hours.
The result of the reaction was a viscous solution having 1.3%
unreacted styrene and 21/2% of ethylhexyl acrylate. The combining
weight of the solution was 1800. The solution could not be diluted
with other polyols but could be diluted with aromatic and
chlorinated hydrocarbons.
Example 2
The product of Example 1 was used to form a cellular polyurethane
product with tolylene diisocyanate having a composition of 80% 2,4-
and 20% 2,6 substitution and having an equivalent weight of 87. The
conventional ratio between the --N=C=O radicals and the other
reactive radicals (such as hydroxyl and carboxyl) was adjusted to
2,8. Hereinafter NCO/X will be used to express this ratio. X being
the sum of the equivalents of all the non-cyanato reactive
radicals. The amount of water was calculated to give a low density
foam.
The product of Example 1 could only be used without dilution;
otherwise solidification took place. To 50 grams of the compound of
Example 1, 1/2 gram of a surface-active silicone oil was added as a
foam stabilizer and to this mixture 1 gram water and 1/2 gram
N-ethyl morpholine was added, the latter serving as a catalyst.
Seven grams of the diisocyanate were then added to this mixture,
resulting in the formation of a very viscous material whose volume
expanded only slightly and which slowly set to a solid. After 24
hours at 70.degree. C., with the formula used, the material had
little strength and appeared to be inferior to other peoducts
obtained according to the present invention. This may be due to the
insufficiency of the quantity of catalyst used.
Example 3
The process of Example 1 was repeated using 55 gm. styrene, 31 gm.
2-ethylhexyl acrylate and 300 gm. Pluracol P2010. The polymer
content of the solution was 22%, which is about half the polymer
content of the solution in Example 1. The reactive solution of
Example 3 was dilutable with further additions of Pluracol P2010
without solidification or other adverse effect.
Example 4
To 100 gm. of the reactive solution of Example 3 are added 0.25 gm.
tin octoate, 2.0 gm. surface active silicone oil, 0.2 gm. N-methyl
morpholine, 0.1 gm. N,N,N',N'-tetramethyl butanediamine, 3.5 gm.
water and 35 gm. tolylene diisocyanate. An excellent polyurethane
foam was obtained having a density of 2.4 lbs./c. ft. and a
compression set (ASTM) of 40%.
Example 5
The flask was charged with 220 gm. styrene, 125 gm. 2-ethylhexyl
acrylate, 32 gm. glacial acrylic acid and 500 gm. of Pluracol P2010
(the polypropylene ether diol used in Example 1). The
polymerization was carried out under the same conditions used in
Example 1, again utilizing 11/2 gm. of azobisisobutyronitrile as a
catalyst.
The resulting polymer solution had 1.3% unreacted styrene, 2%
ethylhexyl acrylate and 0.7% acrylic acid. The combining weight for
the carboxyl radical was determined by titration of the alcoholic
solution with 2 N KOH. The figure determined for the solution was
2950 which, if calculated for the polymer content, was 1200. The
combining weight for all the reactive radicals in the solution
(carboxyls and hydroxyls) was 1060. The polymer content of the
solution was 41%. This solution could be diluted without difficulty
with polyhydric alcohols and was compatible with the
polyisocyanates.
Example 6
25 grams of the reaction product of Example 5 and 25 grams of a
polyoxypropylene triol derived from trimethylol propane and having
a molecular weight of 2600, a hydroxyl number of 63 (mg. KOH/gm.),
a viscosity of 440 cps. at 25.degree. and a combining weight of
890, were mixed together. A uniform solution with a viscosity of
11,000 cps. was obtained.
As in Example 2, 1/2 gram silicon oil, 1.2 grams water and 0.5 gram
N-ethyl morpholine were mixed into the liquid and 121/2 grams of
diisocyanate added. The mixture was poured into a mold of 880 ml.
capacity which was filled in 6 minutes with the foam penetrated by
the chemical reaction. The reaction product solidified in 20
minutes. After a 24-hour cure at 70.degree. C., the product showed
little shrinkage, uniform small cells and low tensile strength.
Example 7
The reaction was carried out under the conditions and procedure of
Example 1, the charge of the flask being:
Gm. ______________________________________ Styrene 220 Ethylhexyl
acrylate 125 Glacial acrylic acid 128 Pluracol P2010 (the
polypropylene ether diol of Example 1) 600 Azobisisobutyronitrile 3
______________________________________
Unreacted monomers were: styrene, 1%; ethylhexyl acrylate, 2.1%;
acrylic acid, 1%. The carboxyl equivalent weight for the solution
was 790 and for the polymer itself 325. The combining weight of the
solution (for the isocyanato radical) was 520. The viscous solution
was compatible with polyols, polyethers and other reactive
additives known to be useful for making polyurethanes.
Example 8
25 grams of the reaction product of Example 7, 25 grams of the
triol in Example 6 and 1/2 gram of the silicone oil were mixed
together. The solution obtained had a viscosity of 15,000 cps. 1.8
grams water and .5 gram N-ethyl morpholine were mixed with this
solution, after which 181/2 grams of the diisocyanate were added. A
foam slowly formed in a mold of 1200 ml. capacity which was finally
filled to the top by the foam. The foam solidified to a resistant
solid in 25 minutes. After 24 hour curing at 70.degree. C., an
excellent cellular material with very high load-bearing capacity,
excellent texture and good strength was obtained. This material was
far superior to the control in the next example.
Example 9
Conventional polyols were used in this experiment while maintaining
the NCO/X ratio at 2.8 and using the same water and isocyanate
ratio as before 25 grams of Pluracol P2010, 25 grams of the triol
previously used and 1/2 gram of silicone oil were mixed together. A
solution of low viscosity of 480 cps. was obtained to which 1.45
grams water and 1/2gram of N-ethyl morpholine were added and,
subsequently, 13.5 grams of the diisocyanate. The liquid mixture
was poured into a mold of 800 ml. capacity. On foaming, a
considerable part of the CO.sub.2 gas escaped and only half of the
800 ml. capacity of the mold was filled with the foam. To obtain a
somewhat resilient product, the foam had to be cured for one week
at 70.degree. C. The product had a very coarse cell structure.
Example 10
A copolymer was prepared using methyl methacrylate as one of the
reactive monomers, as follows:
Gm. ______________________________________ Methyl methacrylate 300
2-ethylhexyl acrylate 100 Acrylic acid 60 Pluracol P2010 500
______________________________________
As a catalyst, 2 gm. azobisobutyronitrile and 1 gm. benzoyl
peroxide were used. A viscous solution resulted, which could be
used in the same manner as the products in Examples 5 and 7. This
solution had a combining weight of 1200 and gave a foam of better
quality than the styrene terpolymer in Example 5.
In this example, all the ingredients used in the polymerization
were of an aliphatic nature.
Example 11
A copolymer was prepared using a hydroxy comonomer. Such a polymer
in reactive with the isocyanate radical, forming methane linkages.
Such a reaction does not produce a gas and the reaction product
with the isocyanate is suitable for making continuous films or
nonporous castings.
For carrying out the polymerization, the reaction flask was charged
with:
Gm. ______________________________________ Styrene 220 2-ethylhexyl
acrylate (whose molecular and com- bining weight was 130: 97.6%
purity) 124.5 Hydroxyethyl methacrylate 64 Pluracol TP440 (a triol
of a molecular weight of 400 and combining weight of 133) 400
______________________________________
The reaction product was a viscous solution with a combining weight
for the hydroxyl of 230.
Example 12
The same formula was used as in Example 11 except that Pluracol
P2010 was used in lieu of Pluracol TP440. Again, a viscous solution
was obtained, with a combining weight of 880.
Example 13
The following ingredients were mixed for the polymerization
reaction:
Gm. ______________________________________ Methyl methacrylate 300
2-ethylhexyl acrylate 100 Hydroxyethyl methacrylate 25 Pluracol
P1010.sup.1 500 Azobisisobutyronitrite 3
______________________________________ .sup.1 A diol with a
molecular weight of 950, a combining weight of 475, viscosity of 75
eps. and corresponding to the formula of the other polypropylene
glycols.
The end product was a very viscous solution with a combining weight
for the OH radical of 725 and having 2% unreacted acrylic
esters.
While the solution was very viscous, it could be diluted with such
polyols as those conventionally used for polyurethane
reactions.
Example 14
To make a cellular compound, the product of Example 12 was reacted
with an isocyanate while using a tin octoate catalyst which was
primarily active in catalyzing the reaction between the isocyanate
and hydroxyl. The NCO/OH ratio was 4.
25 grams of the solution from Example 12 was mixed with 25 grams of
a triol with a molecular weight of 4000 (Pluracol TP4040 of the
Wyandotte Chemical Company). A solution with a viscosity of 15,000
cps. was obtained which could be easily processed, 0.5 gram silicon
oil emulsifier (polysiloxane-polyoxyalkylene block copolymer having
an average molecular weight of about 7000) was mixed in to improve
the foam stability. 15.5 grams tolylene diisocyanate (sold as
Hylene TM by E. I. du Pont de Nemours & Co., Inc., and which is
a mixed isomer consisting of 80% 2,4- and 20% 2,6-substituted
product) was added thereafter. This addition reduced the viscosity
of the material to 3000 cps. and allowed easy mixing with the rest
of the compounding ingredients needed for the formation of the
cellular product, as follows:
Gm. ______________________________________ Tin octoate 0.2 Water
1.4 N-ethyl morpholine 0.5
______________________________________
A foam was produced which, after being cured for 30 minutes at
80.degree. C., was fully solidified and could be removed from the
mold. The density was 2 lbs. per cubic foot, cells small and
uniform (about 0.5 mm. diameter), compression deflection (RMA) at
25% compression after 5 days' aging was 36 lbs. The latter figure
was much higher than that of a foam made by substituting for the
polymer solution in the above formula and a diol (Pluracol P2020 of
the Wyandotte Chemical Company) which had a similar density and
only 15 lbs. RMA compression deflection at 25% compression.
Example 15
The film properties of the reaction product of Example 12 were
studied as follows: 25 grams of the polymer solution of Example 12
and 25 grams of Pluracol TP4040 were compounded with 4.5 grams
tolylene disocyanate (used as before), which combination gave an
NCO/OH ratio of 1.1. This solution remained liquid for 24 hours,
after which it began to gel. A film was cast and allowed to set at
60.degree. C. for 3 days while exposed to moisture in the air. The
0.5 mm. film which was obtained had a tensile strength of 3500
lbs./sq. inch and an elongation of 80%.
Example 16
Using 25 grams of Pluracol TP4040, 25 grams of Pluracol P2020 and
4.5 grams tolylene diisocyanate, a solution was obtained which
remained unchanged in a closed container for over one week. A film
was cast as previously done, which film only set after 5 days.
After 7 days exposure to air, the film had a tensile strength of
800 lbs./sq. inch and an elongation of 20%. It was much softer and
rubbery than the product containing the polymer compound of Example
12.
Examples 17-31
The following polymer solutions are usable in connection with the
instant invention. In each case the film-forming polymer contains
radicals reactive with the cyanato radicals. The polymerization
catalyst used in these reactions was 0.25% azobisisobutyronitrile
calculated on the monomers.
__________________________________________________________________________
Example Monomers Quantity Solvent Quantity No. (grams) (grams)
__________________________________________________________________________
17 Vinyl acetate 300 Pluracol P2010 900 2-ethylhexyl acrylate 60
Acrylic acid 60 18 Itaconic acid (H.sub.2 SO.sub.4, 0.2 gram) 100
Pluracol P1010 (a polypropylene glycol of 1,000 200 molecular
weight and 500 combining weight). 19 Styrene 130 Pluracol P410 (a
polypropylene glycol of 230 Itaconic acid 52 molecular weight and
200 combining weight). 20 Styrene 220 Pluracol P2010 500
2-ethylhexyl acrylate 124 Itaconic acid 62 21 Styrene 100 do 210
Di-n-butyl itaconate 52 Itaconic acid 48 22 Butyl acrylate 220 do
300 Acrylic acid 72 23 Butyl amino-ethyl methacrylate 124 do 400 24
Methyl methacrylate 300 do 500 2-ethylhexyl acrylate 100
Hydroxyethyl methacrylate 64 25 Styrene 260 Pluracol P410 500
Methacrylic acid 148 26 Styrene 260 Pluracol P2010 500 Acrylic acid
148 27 Styrene 260 Pluracol P1010 500 Acrylic acid 148 28 Styrene
260 Pluracol P410 500 Acrylic acid 148 29 Vinyl acetate 450 PPG
2025 (a polypropylene glycol with an 500 2-ethylhexyl acrylate 25
equivalent of 36 mg. KOH/gm. and an average Hydroxypropyl
methacrylate 25 mol. wt. of 2,000). 30 Styrene 110 LG 56 (a
polyoxypropylene triol with an 210 2-ethylhexyl acrylate 62
equivalent of 56.5 mg. KOH/gm. and an Hydroxypropyl methacrylate 16
average mol. wt. of 3,000). 31 Vinyl propionate 570 LG 56 610
Hydroxypropyl methacrylate 30
__________________________________________________________________________
Example 32
In this example, as in Examples 1-3, the film-forming polymer was
made from monomers which did not have an active hydrogen in the
ethylenically unsaturated monomers themselves. The polymerization
was carried out under the conditions and procedures of Example 1,
the charge of the flask being:
Gm. ______________________________________ Vinyl acetate 700
2-ethylhexyl acrylate 27 LG 56 800 Azobisisobutyronitrile 0.75
______________________________________
After the polymerization was completed and the flask cooled, a
viscous solution was formed which could be further diluted with the
I G 56. The solution had a hydroxyl equivalent of 24.5 mg. KOH/gm.
and a free vinyl acetate content or 0.1%. No free acrylic ester
could be detected. The polymer content of the solution was 47.5%.
The viscosity of the solution after dilution with an equal amount
of IG 56 was 4000 cps.
A sample of the solution was treated with petroleum ether which
precipitated the polymer from the polyol solution. The precipitate
was separated by filtration and then extracted in a Soxhlet
extractor using additional petroleum ether. The polymer was then
dissolved from the filter paper with acetone and after evaporating
the acetone was weighed. The precipitated polymer so obtained
constituted 51.3% of the weight of the polymer solution. Based on
the monomer content of the solution of 47.5%, this indicated that
7.8% of the polymer was due to the molecules of the polyol attached
to the polymer chains. The calculated equivalent weight of the
polymer was then about 14,000. The reduced viscosity calculated
from measurement in a 2.5% solution was 0.28.
To determine the reactivity of the solution with an isocyanate, the
following ingredients were reacted:
Gm. ______________________________________ Polymer solution (no
dilution) 100 Silicone oil emulsifier 2 Tetramethyl butane diamine
0.1 Water 3.5 Tolylene diisocyanate 40.7
______________________________________
A cellular product was obtained as before. After aging for 48 hours
at room temperature, the cellular product was shredded and then
extracted with acetone in a Soxhlet extractor. The acetone extract
was 3.9% by weight of the weight of the original cellular product,
indicating that the polymer contained active hydrogen radicals
which had chemically reacted with the isocyanate. When the same
monomers were polymerized in a volatile solvent, then dispersed in
the I G 56 and the resulting polymer solution in the I G 56 made up
into a cellular product using the same formula as above and
extracted with acetone, it was found that 90% of the polymer in the
cellular product was removed by the acetone extraction.
A cellular product was made as in Example 2 using the following
ingredients:
Gm. ______________________________________ Polymer solution 50 LG
56 50 Silicone oil emulsifier 2 Tetramethyl butane diamine 0.1 Tin
octoate 0.36 Water 3.5 Tolylene diisocyanate 41.8
______________________________________
All of the ingredients, except the diisocyanate were first mixed
and then the diisocyanate mixed in over a period of about 30
seconds. In about 10 minutes the product had set to a solid mass.
After aging for 3 days at room temperature it was tested, using as
the control a product prepared using the same formula, but
containing 100 gm. of the pure LG 56 and with 44.5 gm. of the
diisocyanate (the larger amount of the diisocyanate was needed to
compensate for the higher hydroxyl equivalent of the pure LG 56).
The results are tabulated as follows:
Example Control 32 ______________________________________ Density
(lbs./c.ft.) 1.90 1.82 Indentation load (lbs./sq.ft.): Compression
25% 1.2 0.76 Compression 65% 2.5 1.4 Compression 90% l8.8 8.5
Compression set (90% compression), percent 8.7 9.2 Acetone
Solubility, percent 4.8 2.8
______________________________________
These results indicate that the film-forming polymer contained
reactive hydrogen radicals by reason of the chemical attachment of
the polyol molecules with the result that the film-forming polymer
was combined chemically with the polyisocyanate, thereby giving a
polyurethane product of improved properties.
Examples 33-36
Following the same procedure as in Example 32, the following
polymer solutions were prepared which were useful for the same
purpose as those set forth above:
Ex. Nos. 33 34 35 36 ______________________________________
Ingredients Parts by Weight: Vinyl acetate 162 171 173 175
2-ethylhexyl acrylate 18 9 7 4.5 Pluracol P2010 200 200 200 200
______________________________________
In some instances, if the polymerization process is modified so
that the monomers are added to a polyol in a single batch and then
polymerization initiated, the resulting polymer precipitates from
the polyol when formed. However, by adding the monomers
incrementally, a stable, uniform dispersion is produced. In
contrast of this, in the polymerization of other monomers, such as
vinyl acetate and 2-ethylhexyl acrylate, the reverse is true. Thus,
in this latter monomer system, incremental addition of the monomers
as polymerization proceeds results in a copolymer which separates
from the polyol on cooling, while adding the monomers in a single
batch to the polyol and then carrying out the polymerization
results in a uniform solution of the copolymer in the polyol.
Examples 37-41
The following polymer solutions are usable in connection with the
instant invention. The polymerization catalyst used in these
reactions was 0.25% azobisisobutyronitrile calculated on the
monomers.
__________________________________________________________________________
Quantity, Quantity, Example Monomer parts Solvent parts
__________________________________________________________________________
37 Styrene 53 PPG 2025 156 2-ethylhexyl acrylate 30 Acrylamide 17
38 Styrene 52 PPG 425* 92 2-ethylhexyl acrylate 20 t-Butylamino
methacrylate 19 39 Vinyl propionate 100 PPG 2025 127 40 Vinyl
butyrate 100 PPG 2025 100 41 Butyl acrylate 75 PPG 2025 100 Acrylic
acid 25
__________________________________________________________________________
*A polypropylene glycol having a hydroxyl number of 265 and a
molecular weight of about 400.
In the above solutions the vinyl butyrate solution had a
significantly higher viscosity than the vinyl propionate solution.
The solution of Example 38 is also noteworthy in that the solution
produced by the polymerization gelled somewhat; howver, it was
easily dilutable with further additions of the polyol.
Examples 42-45
Reactive solutions were prepared as described in Examples 37
through 41, using in Example 42 a monomer mixture of 96 parts vinyl
acetate to 4 parts 2-ethylhexyl acrylate; in Example 43 vinyl
propionate; in Example 44 vinyl butyrate and in Example 45 vinyl
2-ethylhexoate. In each case the polyol used as the solvent for the
polymerization was LG 56. A cellular polyurethane foam was then
prepared from these reactive solutions using the procedures shown
in Example 32. The resulting foams were then cut up into small
pieces and extracted to constant weight in a Soxhlet extractor
using acetone. A polyurethane was prepared from LG 56 without any
polymer present and subjected to the same extraction to serve as a
control. The results are set forth in the following table:
Total Polymer Content Amount Chemically of Poly- extracted
Chemically bound urethane (weight bound polymer (weight percent of
polymer (corrected Example percent) sample) (percent) percent)
______________________________________ 42 32.5 3.9 87 95 24.3 2.7
88.5 99.9 43 33.2 10.3 68.6 77 25 4.7 81.5 91 44 25 3.4 86 96 45 25
3 88 98 Control 2.4 ______________________________________
Each of the polymers in these examples was prepared from monomers
which do not contain an active hydrogen group which would be
reactive with the isocyanato group. Thus these examples clearly
show that some of the polyol has been chemically attached to the
polymer with the result that a significant reaction occurs between
the isocyanato group and the film-forming polymer in the
polyol.
When the same procedure as in Example 32 is used to separate the
polymer from the polyol, again an increase in weight of the
recovered polymer was found indicating that some of the molecules
of the polyol were attached to the polymer. Thus the polymers and
copolymers produced by the solution polymerization of ethylenically
unsaturated monomers in a polyol solution have significantly
altered properties from those that would be obtained if the
polymerization were carried out in a completely inert solvent. At
the same time the degree of reactivity is such that the
polymerization of the monomers is not interfered with and proceeds
to completion without gelling or other adverse effect.
Example 46
An ester was prepared by heating azelaic acid and ethylene glycol
in a ratio of 1 mol of acid to 2 mols of glycol and removing the
water of condensation to yield a polyester having an acid number of
44 and a hydroxyl number of 244. Utilizing the polyester so formed
as the solvent for preparing the reactive solution of the
invention, 100 gm. of vinyl butyrate were added to 210 gm. of the
polyester. The solution was heated under a nitrogen blanket to
about 80.degree. C. at which point it started to show substantial
reflux. The catalyst was then added, in this case 0.5 gm. of
azobisobutyronitrile. Upon completion of the polymerization there
was obtained a clear solution having 0.46% unreacted monomer and
possessing a hydroxyl equivalent of 172 which could be used in
preparing a rigid cellular polyurethane product.
Example 47
A polyester was prepared as in Example 46 using 2 mols of azelaic
acid and 3 mols of ethylene glycol. The resulting polyester had a
relatively high viscosity, an acid number of 11 and a hydroxy
number of 48. To 200 gm. of the polyester there were added 150 gm.
of vinyl butyrate and the monomer was polymerized as in EXample 49,
excepting that a higher concentration of catalyst was employed, in
this case 1.5 gm. of the azobisisobutyronitrile. Again a clear
viscous solution was obtained which was suitable for making a
cellular polyurethane product.
Example 48
In a stainless steel autoclave equipped with a stirrer and
temperature control means, a reactive composition of polyisoprene
in LG 56 triol was produced using 1600 parts of LG 56 triol, 20
parts of dibenzoyl peroxide in 118 parts of acetone and 400 parts
of isoprene. The reaction period was about 27 hours, at about
80.degree. C. to 90.degree. C. After vacuum distillation, the
reactive composition was gray-white in color, had a viscosity of
1,000 cps. at 25.degree. C., an average hydroxyl number of about
44.8 and a 20% polyisoprene content.
Foams were produced from this reactive composition using the
following recipes: Run A B C
__________________________________________________________________________
Reactive Composition 100 75 25 Polyol (LG 56) 0 25 75 Emulsifier (A
polysiloxane-polyoxyalkalene block copolymer having a total average
molecular weight of about 7,000) 2 2 2 Water 3.5 3.5 3.5 TMBDA
(N,N,N',N'-tetramethyl-1,3- butanediamine) 0.1 0.1 0.1 Stannous
octoate 0.3 0.3 0.3 Tolylene diisocyanate 42.7 43.2 44.2 Their
characteristics were: Rise time (sec.) 150 138 102 Tensile (p.s.i.)
14.6 14.9 14.9 Elongation (percent) 145 160 140 Density
(lbs./ft..sup.3) 1.78 1.78 1.68 Indentation load deflection
(p.s.i.): 25% 0.85 0.69 0.75 65% 1.7 1.5 1.6 90% 9.7 8.2 8.0 Yield
point Deflection (percent) 4.2 5.2 4.2 Load (p.s.i.) 0.73 0.57 0.63
__________________________________________________________________________
Example 49
In a manner similar to that described in Example 48, a reactive
composition of polyisoprene in LG 56 triol was produced using 1800
parts of LG 56 triol, 20 parts of dibenzoyl peroxide and 200 parts
of isoprene. The reaction period was about 20 hours at about
85.degree. C. to 90.degree. C. After vacuum distillation the
polyisoprene/polyol was slightly hazy, had a viscosity of 760 cps.
at 25.degree. C., an average hydroxy number of about 46.3 and a 10
percent polyisoprene content.
Foams were produced from this reactive composition using the
following recipes: Run A B C ______________________________________
Reactive Composition 100 75 25 Polyol (LG 56) 0 25 75 Emulsifier 2
2 2 Water 3.5 3.5 3.5 TMBDA 0.1 0.1 0.1 Stannous octoate 0.3 0.3
0.3 Tolylene diisocyanate 43.0 43.4 44.2 Their characteristics
were: Rise time (sec.) 138 137 100 Tensile (p.s.i.) 21.4 13.6 15.5
Elongation (percent) 130 124 138 Density (lbs./ft..sup.3) 1.80 1.63
1.60 Indentation load deflection (p.s.i.): 25% 0.84 0.72 0.74 65%
1.7 1.4 1.5 90% 9.4 7.0 7.3 Yield point: Deflection (percent) 4.7
4.3 4.1 Load (p.s.i.) 0.71 0.59 0.62
______________________________________
Example 50
In a manner similar to that described in Example 48, a reactive
composition of poly(butadiene/styrene) in LG 56 triol was produced
using 1800 parts of LG 56 triol, 150 parts of butadiene, 50 parts
of styrene, and 20 parts of dibenzoyl peroxide in 222 parts of
benzene. The reaction period was about 10.5 hours at about
87.degree. C. After vacuum distillation the copolymer/polyol
composition was hazy and dull white in color and had an average
hydroxyl number of about 61.5.
Foams were produced from this reactive composition using the
following recipes:
Run A B C ______________________________________ Reactive
composition 100 50 25 Polyol (LG 56) 0 50 75 Emulsifier 2 2 2 Water
3.5 3.5 3.5 TMBDA 0.1 0.1 0.1 Stannous octoate 0.3 0.3 0.3 Tolylene
diisocyanate 45.5 45.1 44.9 Their characteristics were: Rise time
(sec.) 143 105 92 Tensile (p.s.i.) 21.4 19.1 18.9 Elongation
(percent) 193 209 204 Density (lbs./ft..sup.3) 1.85 1.67 1.69
Indentation load deflection (p.s.i.): 25% 0.73 0.69 0.63 65% 1.5
1.3 1.2 90% 8.8 6.1 6.4 Yield point: Deflection (percent) 3.6 4.5
3.9 Load (p.s.i.) 0.60 0.60 0.57
______________________________________
Example 51
In a manner similar to that described in Example 48, a reactive
composition of poly(butadiene/styrene) in LG 56 triol was produced
using 1800 parts of LG 56 triol, 150 parts of butadiene, 50 parts
of styrene, and 20 parts of dibenzoyl peroxide. The reaction period
was about 10 hours at 80.degree. C. to about 89.degree. C. After
vacuum distillation the copolymer/polyol composition was hazy
white, had an average hydroxyl number of about 48.1, 2.5%
polymerized styrene, and 7.5% polymerized butadiene.
Foams were produced from this reactive composition using the
following recipes:
Run A B C ______________________________________ Reactive
composition 100 75 25 Polyol (LG 56) 0 25 75 Emulsifier 2 2 2 Water
3.5 3.5 3.5 TMBDA 0.1 0.1 0.1 Stannous octoate 0.3 0.3 0.3 Tolylene
diisocyanate 43.3 43.7 44.3 Their characteristics were: Rise time
(sec.) 120 115 83 Tensile (p.s.i.) 15.2 19.6 14.6 Elongation
(percent) 171 185 178 Density (lbs./ft..sup.3) 1.68 1.50 1.67
Indentation load deflection (p.s.i.): 25% 0.85 0.80 0.78 65% 1.6
1.5 1.5 90% 8.3 7.0 8.3 Yield point: Deflection (percent) 50 38 11
Load (p.s.i.) 0.85 0.78 0.68
______________________________________
As was noted previously, polymeric amino compounds, particularly
tertiary amines, will serve as catalysts for the polyurethane
formation and no further catalyst components are necessary. This
may be illustrated by the following example.
Example 52
In the manner described previously, 150 grams of
dimethylaminoethylacrylate, 100 grams of a trifunctional polyol,
and 1 gram of azobisisobutyronitrile catalyst were mixed in a
three-neck flask as described previously. The trifunctional polyol
had been prepared by the addition of propylene oxide to glycerol
and had an average molecular weight of 3,000 and an OH equivalence
of 56 mg. KOH per gm. the dimethylaminoethylacrylate was freed from
inhibitor by passing it through columns packed with charcoal and
absorbant silica gel. The flask contents were heated under a
nitrogen blanket and agitated for 9 hours at 80.degree. C. A clear
yellowish liquid resulted which had an unrecated monomer content of
21/2% and a viscosity of 1100 cps. at 25.degree. C. This reactive
composition formed a stable emulsion when mixed with water and
could be diluted without difficulty with other polyols and with
components necessary for urethane formation. To produce a cellular
plastic 20 gm. of the reactive composition were mixed with 80 gm.
of the same polyol used in the preparation of the reactive
composition. 2 parts of a silicone surface-active agent, and 0.5
gm. of tin octoate and 2.9 gm. of water. To this mixture were added
37 gm. of tolylene diisocyanate. The resulting cellular foam had a
foam rise time of 40 seconds and solidified within 80 seconds after
mixing with the isocyanate. Surface tacking disappeared after 2
minutes; after 30 minutes the foam had set to a coherent strong
plastic with negligible shrinkage. When heated for 30 minutes at
80.degree. C. a strong elastic product was obtained which had
excellent properties and no amine odor.
When the polymer formed in the polyol or other reactive solvent is
a nitrogen derivative which has catalytic activity in the
polyurethane reaction as exemplified above and as described
previously, the requirement that the polymer be a film-former may
be relaxed since the main function of the polymer is that of a
catalyst. this last example clearly demonstrates that tertiary
amines can be replaced by catalytically active polymers which are
nitrogen derivatives to produce good polyurethane products. Since
the nitrogen-containing polymer is of low volatility as compared to
the usual amine catalysts, the urethane products have substantially
no odor.
In addition to the various previously mentioned advantages of the
instant process and improved products, still additional advantages
result from the practice of the present invention. For example, the
use of a reactive solvent rather than a mere diluent makes
unnecessary its removal from the finished product and avoids the
shrinkage which invariably attends such removal.
A further advantage lies in the use of the solutions of the present
invention to increase the viscosity of the composite mixture used
for the production of the polyurethanes, which improves the flow
properties of the liquids for most of the applications. When making
cellular expanded type products, the high viscosity of the mixture
will prevent premature escape of gases from the foam cells and a
fine-textured product can be produced. Such premature escape of
gases frequently causes difficulties in a "one-shot" process. As a
result, the prior art limitation to the use of polyesters,
polyethers and other prepolymers of high viscosity for the
polyurethane reaction is removed. The film-forming polymers act as
"bodying" agents in the reactive solutions so that the so-called
"one-shot" process can be used more effectively.
Still another advantage of the process of the present invention is
the improvement in the load-bearing characteristics of foam
products as well as the tensile strength and stability of the foam
cells. When nonporous films are made, their hardness, flexibility,
abrasion resistance, tensile strength, elongation, rebound and, in
general, all of their physical properties can be favorably altered
by using the process of the present invention. Thus, film-forming
polymers may be easily combined chemically into the polyurethane to
produce a new class of polymers having properties more valuable
than either material alone. Plasticizers for the polymer compounds
can be used. Other modifiers can be used such as polymers having
reactive radicals, but not reactive with the NCO radical. In this
latter case, the remaining reactive sites, such as double bond and
unreacted carboxyls, can be used as additional cross-linking
sites.
Where it is desired to increase the number of reactive groups on
the polymer chain formed in the reactive solvent, and where it is
desired to introduce a species of reactive group into the polymer
so formed which is different from the reactive groups present on
the polymer and in the reactive solvent, monomers with the desired
reactive groups can be further grafted to the polymer backbone;
thus a reactive composition can be produced containing a polymer
having a number of different species of reactive groups even though
the reactive solvent and the polymer formed in the reactive solvent
were initially free from such groups. Thus the reactive groups may
be altered and/or new groups may be introduced into the polymer,
for example, by hydrolyzing the polymer (as hydrolyzing polyvinyl
acetate to introduce hydroxyls), by grafting (as in grafting
acrylic acid, et cetera, on a polymerized diene, as described in
U.S. 2,859,201), by oxidation (as shown, for example, in U.S.
2,762,790), et cetera. See also U.S. 2,837,496.
The extreme versatile nature of the process of the instant
invention makes possible the production of products having a wide
variety of characteristics, and can effectively be used for forming
not only cellular polyurethane products, but films, coatings, cast
or molded articles, et cetera. As is well known, cellular
polyurethane products may be obtained by inducing the polyurethane
products may be obtained by inducing the polyurethane reaction in
the presence of a gas-producing agent or "blowing agent" such as
water, fluorohydrocarbons, et cetera.
The term "polyurethane," when used in the specification and claims,
is to be broadly construed to embrace the polymeric reaction
product of isocynates with compounds containing radicals reactive
with the --N=C=O radicals of said isocyanates. What is claimed
is:
* * * * *