Polymer polyol and flame retardant polyurethane foams

Polymer dispersion polyols made by the free radical polymerization of a monomer mixture of at least a maleimide monomer and a copolymerizable styrenic monomer in an organic polyl medium are disclosed. The resulting polymer polyols are suitable for use to prepare flame retardant polyurethanes.

This invention relates to polyurethane polymers. 
More specifically, this invention relates to polymer dispersions in polyols 
used in the preparation of flame retardant polyurethane foams. 
In one of its more specific aspects, this invention pertains to stable, 
fluid polymer polyols made by the free radical polymerization of a monomer 
mixture of a maleimide monomer and a copolymerizable styrenic monomer in 
an organic polyol medium. 
Graft copolymer dispersions prepared from vinyl monomers and polyether 
polyols and their use in the preparation of polyurethane polymers are well 
known. The pioneer patents in the field of polymer polyols are U.S. Pat. 
Nos. 3,304,273; 3,383,351; Re. 28,715; Re. 29,118; and 3,523,093 to 
Stamberger, and U.S. Pat. No. 3,652,639 to Pizzini, et al. In the patents 
to Stamberger, the method involves the in situ polymerization of a nitrile 
monomer (e.g., acrylonitrile and methacrylonitrile) in high molecular 
weight polyols. Pizzini, et al.'s method involves incorporating 
unsaturation into a polyol to increase the resultant level of grafting 
onto the polyol. The unsaturated polyol is typically prepared by the 
reaction of a saturated primary polyol with maleic anhydride followed by 
capping with ethylene oxide to reduce acidity. 
Polymer polyols that found initial commercial acceptance were primarily 
produced from polyols and acrylonitrile. More recently, polymer polyols 
produced from polyols, acrylonitrile, and styrene have been the commerical 
standards. U.S. Pat. No. 4,198,488 to Drake, et al. teaches a further 
improvement to the method of Stamberger and involves the addition of a 
small amount (preferably 2.5 to 6 weight percent) of maleic anhydride to 
an acrylonitrile/styrene monomer feed. Drake, et al. teaches that a 
portion of the maleic anhydride units polymerize into the polymer backbone 
and react with the hydroxyl groups of the polyol. 
The present invention provides a stable polymer polyol dispersion from a 
maleimide monomer. The polymer polyol of the invention can be prepared in 
the absence of a nitrile monomer and without using modified (unsaturated) 
polyols. The advantage of a process which facilitates the production of a 
polymer polyol in the absence of acrylonitrile is obvious due to 
acrylonitrile's high toxicity and its tendency to produce discolored 
dispersions resulting in scorched foams. Quite surprising were the 
discoveries that the use of the maleimide monomer resulted in a high level 
of grafting and that the maleimide monomer produced polyurethane foams 
having superior flame retardancy. 
According to this invention, there is provided a polymer polyol suitable 
for reaction with an isocyanate to form a polyurethane comprising the 
reaction product prepared at a temperature within the range of from about 
70.degree. C. to about 150.degree. C. under free radical conditions from a 
minor amount of a monomer mixture and a major amount of an organic polyol 
medium wherein: 
(a) the monomer mixture comprises at least a first and a second monomer, 
wherein said first monomer is a maleimide monomer, and said second monomer 
is a styrenic monomer which is polymerizable with said first monomer; 
(b) the organic polyol medium consists essentially of polyoxyalkylene 
polyether polyol. 
Also according to this invention, there is provided a polyurethane 
composition comprising the reaction product of: 
(a) a polymer polyol comprising the reaction product prepared at a 
temperature within the range of from about 70.degree. C. to about 
150.degree. C. under free radical conditions from a minor amount of a 
monomer mixture and a major amount of an organic polyol medium, wherein 
(i) the monomer mixture comprises at least a first and a second monomer, 
wherein the first monomer is a maleimide monomer and is employed in the 
monomer mixture in an amount sufficient to improve the flame retardancy of 
the polyurethane composition as compared to the flame retardancy of the 
polyurethane composition in the absence of said maleimide monomer, and the 
second monomer is a styrenic monomer which is copolymerizable with the 
maleimide monomer, 
(ii) the organic polyol medium consists essentially of polyoxyalkylene 
polyether polyol; and 
(b) a polyisocyanate. 
In one embodiment of this invention, the essential components of the 
polymer polyol are a maleimide monomer, a styrenic monomer polymerizable 
with the maleimide monomer, and a polyol; the monomer mixture containing 
in mole percent from about 25 to about 50 of total maleimide monomers and 
from about 75 to about 50 of total styrenic monomers. 
The polyols suitable for use are one or more polyoxyalkylene polyether 
polyols which are the polymerization products of an alkene oxide or a 
mixture of alkene oxides with a polyhydric alcohol. The polyol may contain 
small amounts of unsaturation or may be modified to contain small amounts 
of unsaturation. The molecular weight of the polyol will be within the 
range of from about 100 to about 11,000, preferably from about 2,000 to 
about 6,500. 
The monomer mixture according to the invention will contain at least one 
maleimide monomer selected from the group consisting of maleimide, 
N-arylmaleimides, and N-alkylmaleimides. Suitable maleimide monomers 
include maleimide, N-phenylmaleimide, N-methyl maleimide, N-ethyl 
maleimide, N-tolylmaleimide, N-(2,4,6-tribromophenyl)maleimide, 
2-chlorophenylmaleimide, 4-chlorophenylmaleimide, and the like and their 
mixtures. N-phenylmaleimide is preferred. 
The monomer mixture will also contain at least one styrenic monomer which 
is polymerizable with the maleimide monomer. Any suitable styrenic monomer 
or mixture of styrenic monomers can be employed. Suitable styrenic 
monomers include styrene, substituted styrenes such as 
.alpha.-methylstyrene, .rho.-methylstyrene, chloromethylstyrene, vinyl 
toluene, and the like, and their mixtures. Styrene is the preferred 
styrenic monomer. 
Although the monomer mixture employed to produce the polymer polyols of the 
invention is preferably a mixture of maleimide monomers and styrenic 
monomers, the mixture can comprise other monomers in addition to the 
maleimide and the styrenic monomers, provided the other monomer is 
copolymerizable with the maleimide and the styrenic monomers. Other 
monomers which can be incorporated during the polymerization reaction 
include acrylates, methacrylates, acrylamides, and their derivatives, 
.alpha., .beta.-ethylenically unsaturated dicarboxylic acid anhydrides, 
vinyl and vinylidene halides, and nitrile derivatives such as 
acrylonitrile and methacrylonitrile. If one or more other monomers are 
present during the polymerization reaction, it is possible to reduce the 
minimum amounts of maleimide and styrenic monomers such that the monomer 
mixture contains in mole percent from about 3 to about 50 total maleimide 
monomers, from about 20 to about 75 total styrenic monomers, and up to 65 
total other monomers. Preferably, the other monomers, if employed, will be 
present in a total amount of from about 5 to about 65 mole percent. 
The polymer polyol of the present invention can be produced by polymerizing 
the monomer mixture in the selected polyol at a temperature of from about 
70.degree. C. to about 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 (initiator) generally will vary within the 
range of from about 0.2 to about 5 weight percent based on the weight of 
the monomer mixture. However, any amount sufficient to cause grafting is 
satisfactory. Illustrative catalysts are the well-known free radical 
types; for example, hydrogen peroxide, t-butyl peroctoate, lauryl 
peroxide, cumene hydroperoxide, t-butyl hydroperoxide, benzoyl peroxide, 
and azobis(isobutyronitrile). 
In the practice of the invention, the monomer mixture is employed in an 
amount within the range of from about 5 to about 45 weight percent, based 
on the total weight of the monomer mixture and the polyol. Preferably, the 
monomer mixture will be employed within the range of from about 15 to 
about 40 weight percent, based on the weight of the monomer mixture and 
the polyol. 
Any conventional process for preparing polymer polyols can be employed to 
prepare the polymer polyols of this invention. Preferred is a process 
which maintains high agitation and a low monomer to polyol ratio 
throughout the reaction mixture during the process. Both batch and 
continuous processes are suitable 
The polymerization can also be carried out with an inert organic solvent 
present. The solvent must be inert, that is, it must not hinder the 
polymerization reaction. Illustrative solvents are toluene, benzene, 
acetonitrile, ethyl acetate, hexane, heptane, dicyclohexane, dioxane, 
acetone, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, 
and the like, and their mixtures. When an inert organic solvent is used, 
it is preferably removed by conventional means. 
The polyurethane foams of the present invention are generally prepared by 
the reaction of the graft copolymer dispersion of the invention, with an 
organic polyisocyanate in the presence of a blowing agent and optionally 
in the presence of conventionally employed amounts of additional 
polyhydroxyl-containing components, chain-extending agents, catalysts, 
surface-active agents, stabilizers, fire retardant compounds, dyes, 
fillers, and pigments. Suitable processes for the preparation of cellular 
polyurethane plastics are disclosed in U.S. Pat. No. Re. 24,514, together 
with suitable machinery to be used in conjunction therewith. When water is 
added as the blowing agent, corresponding quantities of excess isocyanate 
to react with the water and produce carbon dioxide may be used. It is also 
possible to proceed with the preparation of the polyurethanes by a 
prepolymer technique, wherein an excess of organic polyisocyanate is 
reacted in a first step with the polyol of the present invention to 
prepare a prepolymer having free isocyanate groups, which is then reacted 
in a second step with water to prepare a foam. Alternately, the components 
may be reacted in a single working step commonly known as the "one-shot" 
technique of preparing polyurethanes. Furthermore, instead of water, low 
boiling hydrocarbons such as pentane, hexane, heptane, pentene, and 
heptene; azo compounds such as azohexahydrobenzodinitrile; halogenated 
hydrocarbons such as dichlorodifluoromethane, trichlorofluoromethane, 
dichlorodifluoroethane, vinylidene chloride, and methylene chloride may be 
used as blowing agents. 
Organic polyisocyanates which may be employed include aromatic, aliphatic, 
and cycloaliphatic polyisocyanates and combinations thereof. 
Representative of these types are the diisocyanates such as m-phenylene 
diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, mixtures 
of 2,4- and 2,6-toluene diisocyanate, hexamethylene-1,6-diisocyanate, 
tetramethylene-1,4-diisocyanate, cyclohexane-1,4-diisocyanate, 
hexahydrotoluene diisocyanate (and isomers), naphthylene-1,5-diisocyanate, 
1-methoxyphenyl-2,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, 
4,4'-biphenylene, 3,3'-dimethyl-4,4'-biphenyl diisocyanate, and 
3,3'-dimethyldiphenylmethane-4,4'-biphenyl diisocyanate; the 
triisocyanates such as 4,4',4"-triphenylmethane triisocyanate, 
polymethylene polyphenylisocyanate and tolylene 2,4,6-triisocyanate; and 
the tetraisocyanates such as 
4,4'-dimethyldiphenylmethane-2,2'-5,5'-tetraisocyanate. Especially useful 
due to their availability and properties are toluene diisocyanate, 
diphenylmethane-4,4'-diisocyanate, and polymethylene polyphenylisocyanate. 
Crude polyisocyanate may also be used in the compositions of the present 
invention, such as crude toluene diisocyanate obtained by the phosgenation 
of a mixture of toluene diamines or crude diphenylmethane isocyanate 
obtained by the phosgenation of crude diphenylmethyl diamine. The 
preferred unreacted or crude isocyanates are disclosed in U.S. Pat. No. 
3,215,652. 
As mentioned above, the graft polyols may be employed along with another 
polyhydroxyl-containing component commonly employed in the art. Any of the 
polyhydroxyl-containing components which are described above for use in 
the preparation of the graft polyols may be employed in the preparation of 
the polyurethane foams useful in the present invention. 
Chain-extending agents which may be employed in the preparation of the 
polyurethane foams include those compounds having at least two functional 
groups bearing active hydrogen atoms such as water, hydrazine, primary and 
secondary diamines, amino alcohols, amino acids, hydroxy acids, glycols, 
or mixtures thereof. A preferred group of chainextending agents includes 
water and primary and secondary diamines which react more readily with the 
prepolymer than does water such as phenylene diamine, 
1,4-cyclohexanebis(methylamine), ethylene diamine, diethylene triamine, 
N-(2-hydroxypropyl)ethylene diamine, N,N'-di(2-hydroxypropyl)ethylene 
diamine, piperazine, 2-methylpiperazine, and morpholine. 
Any suitable catalyst may be used, including tertiary amines such as, for 
example, triethylene diamine, N-methyl morpholine, N-ethyl morpholine, 
diethyl ethanolamine, N-cocomorpholine, 1-methyl-4-dimethylamino ethyl 
piperazine, 3-methoxy-N-dimethyl propylamine, N-dimethyl-N'-methyl 
isopropyl propylenediamine, N,N'-diethyl-3-diethyl amino propylamine, 
dimethyl benzylamine, and the like, and their mixtures. Other suitable 
catalysts are, for example, tin compounds such as stannous chloride, tin 
salts of carboxylic acids such as dibutyltin di-2-ethyl hexoate, tin 
alcoholates such as stannous octoate, as well as other organo metallic 
compounds such as are disclosed in U.S. Pat. No. 2,846,408. 
A surface-active agent is generally necessary for production of high grade 
polyurethane foam according to the present invention, since in its 
absence, the foams collapse or contain very large uneven cells. Numerous 
surfactants have been found satisfactory. Non-ionic surfactants are 
preferred. Of these, the non-ionic surface-active agents prepared by the 
sequential addition of propylene oxide and then ethylene oxide to 
propylene glycol and the solid or liquid organosilicones have been found 
particularly desirable. Other surface-active agents which are operative, 
although not preferred, include polyethylene glycol ethers of long chain 
alcohols, tertiary amino or alkylolamine salts of long chain alkyl acid 
sulfate esters, alkyl sulfonic esters, and alkyl arylsulfonic acids. 
It has been observed that polyurethane foam products which have 
incorporated therein the graft polymer dispersions of the invention 
require less flame retardant compound to impart flame retardancy. 
Moreover, equivalent flame retardancy can be achieved using the graft 
polymer dispersions of the invention and less flame retardant compound as 
compared to the amount of flame retardant compound needed using graft 
polymer dispersions of the prior art. Among the flame retardants which may 
be employed are: pentabromodiphenyl oxide, dibromopropanol, 
tris(.beta.-chloropropyl)phosphate, 2,2-bis(bromoethyl) 1,3-propanediol, 
tetrakis(2-chloroethyl)ethylene diphosphate, 
tris(2,3-dibromopropyl)phosphate, tris(.beta.-chloroethyl)phosphate, 
tris(1,2-dichloropropyl)phosphate, bis-(2-chloroethyl), 
2-chloroethylphosphonate, molybdenum trioxide, ammonium molybdate, 
ammonium phosphate, pentabromodiphenyloxide, tricresyl phosphate, 
hexabromocyclododecane, and dibromoethyldibromocyclohexane.

The invention is illustrated by the following examples. 
EXAMPLE 1 
This example demonstrates the preparation of a styrene/N-phenylmaleimide 
graft copolymer dispersion of the invention. 
Into a 1 liter, 4 neck round-bottom flask equipped with a stirrer, 
condenser, thermometer, and addition tube, and under a blanket of 
nitrogen, was charged 319 g of a glycerin started polyether of propylene 
oxide and ethylene oxide containing about 13% ethylene oxide having a 
hydroxyl number of 56 and containing essentially secondary OH groups 
(Polyol A). After heating Polyol A to 110.degree. C. and maintaining that 
temperature for about 30 minutes, the following monomer charge was added 
over a 2-hour period to give a milk-white dispersion. 
______________________________________ 
Monomer Charge 
Ingredient Amount (g) 
______________________________________ 
Styrene 44.9 
N--phenylmaleimide 74.6 
Toluene 50.0 
Tetrahydrofuran 100.0 
Azobis(isobutyronitrile) (AIBN) 
2.0 
Polyol A 159.0 
______________________________________ 
Upon completion of the addition, the dispersion was held at 110.degree. C. 
for 30 minutes, then the reaction mixture was stripped for 2.5 hours at 
90.degree. C. and 1 mm Hg to yield a stable polymer polyol dispersion. The 
polymer polyol dispersion was found to have a viscosity of 2,670 cps 
(Brookfield cone and plate viscometer spindle #CP-52, 2.5 rpm @ 26.degree. 
C.) and a solids content by hexane extraction of 26.9%. The resulting 
styrene/N-phenylmaleimide graft copolymer was diluted to a 20% solids 
level with Polyol A, and after dilution had a viscosity of 1,380 cps. 
EXAMPLE 2 
This example demonstrates the preparation of another 
styrene/N-phenylmaleimide graft copolymer dispersion of the invention. 
Into a 1 liter, 4 neck round-bottom flask equipped with a stirrer, 
condenser, thermometer, and addition tube, and under a blanket of 
nitrogen, was charged 319 g of a glycerin started polyether of propylene 
oxide and ethylene oxide with an OH number of 25 and a primary OH group 
content of about 80%-85% based on the total OH content of the polyether 
(Polyol B). After heating Polyol B to 110.degree. C. and maintaining that 
temperature for about 30 minutes, the following monomer charge was added 
over a 2-hour period to give a milk-white dispersion. 
______________________________________ 
Monomer Charge 
Ingredient Amount (g) 
______________________________________ 
Styrene 60.0 
N--phenylmaleimide 
60.0 
Toluene 50.0 
Tetrahydrofuran 40.0 
AIBN 3.0 
Polyol B 159.0 
______________________________________ 
Upon completion of the addition, the dispersion was held at 110.degree. C. 
for 30 minutes, then the reaction mixture was stripped for 2.5 hours at 
90.degree. C. and 1 mm Hg to yield a stable polymer polyol dispersion. The 
polymer polyol dispersion was found to have a viscosity of 17,900 cps 
(Brookfield cone and plate viscometer spindle #CP-52, 2.5 rpm @ 26.degree. 
C.). 
EXAMPLE 3 
This example demonstrates the preparation of another 
styrene/N-phenylmaleimide graft copolymer dispersion of the invention. 
Into a 1 liter, 4 neck round-bottom flask equipped with a stirrer, 
condenser, thermometer, and addition tube, and under a blanket of 
nitrogen, was charged 638 g of Polyol B. After heating Polyol B to 
110.degree. C. and maintaining that temperature for about 30 minutes, the 
following monomer charge was added over a 2-hour period to give a 
milk-white dispersion. 
______________________________________ 
Monomer Charge 
Ingredient Amount (g) 
______________________________________ 
Styrene 53.2 
N--phenylmaleimide 
53.0 
Toluene 100.0 
Tetrahydrofuran 20.0 
AIBN 3.0 
Polyol B 638.0 
______________________________________ 
Upon completion of the addition, the dispersion was held at 110.degree. C. 
for 30 minutes, then the reaction mixture was stripped for 2.5 hours at 
90.degree. C. and 1 mm Hg to yield a stable polymer polyol dispersion. The 
polymer polyol dispersion was found to have a viscosity of 3,150 cps 
(Brookfield cone and plate viscometer spindle #CP-52, 2.5 rpm @ 26.degree. 
C.). 
EXAMPLE 4 
This example demonstrates the preparation of another 
styrene/N-phenylmaleimide graft copolymer dispersion of the invention. 
Into a 1 liter, 4 neck round-bottom flask equipped with a stirrer, 
condenser, thermometer, and addition tube, and under a blanket of 
nitrogen, was charged 319 g of a glycerin started polyether of propylene 
oxide and ethylene oxide having an hydroxyl number of 35 and a primary OH 
group content of about 75%-80% based on the total OH content of the 
polyether (Polyol C). After heating Polyol C to 110.degree. C. and 
maintaining that temperature for about 30 minutes, the following monomer 
charge was added over a 2-hour period to give a milk-white dispersion. 
______________________________________ 
Monomer Charge 
Ingredient Amount (g) 
______________________________________ 
Styrene 26.6 
N--phenylmaleimide 
26.5 
Toluene 50.0 
Tetrahydrofuran 10.0 
AIBN 1.5 
Polyol C 159.0 
______________________________________ 
Upon completion of the addition, the dispersion was held at 110.degree. C. 
for 30 minutes, then the reaction mixture was stripped for 2.5 hours at 
90.degree. C. and 1 mm Hg to yield a stable polymer polyol dispersion. The 
polymer polyol dispersion was found to have a viscosity of 1,570 cps 
(Brookfield cone and plate viscometer spindle #CP-52, 2.5 rpm @ 26.degree. 
C.). 
EXAMPLE 5 
This example demonstrates the preparation of another 
styrene/N-phenylmaleimide graft copolymer dispersion of the invention. 
Into a 1 liter, 4 neck round-bottom flask equipped with a stirrer, 
condenser, thermometer, and addition tube, and under a blanket of 
nitrogen, was charged 319 g of Polyol C. After heating Polyol C to 
110.degree. C. and maintaining that temperature for about 30 minutes, the 
following monomer charge was added over a 2-hour period to give a 
milk-white dispersion. 
______________________________________ 
Monomer Charge 
Ingredient Amount (g) 
______________________________________ 
Styrene 60.6 
N--phenylmaleimide 
60.5 
Toluene 50.0 
Tetrahydrofuran 50.0 
AIBN 3.0 
Polyol C 159.0 
______________________________________ 
Upon completion of the addition, the dispersion was held at 110.degree. C. 
for 30 minutes, then the reaction mixture was stripped for 2.5 hours at 
90.degree. C. and 1 mm Hg to yield a stable polymer polyol dispersion. The 
polymer polyol dispersion was found to have a viscosity of 3,930 cps 
(Brookfield cone and plate viscometer spindle #CP-52, 2.5 rpm @ 26.degree. 
C.). 
EXAMPLE 6 
This example demonstrates the preparation of a graft copolymer dispersion 
of the invention using both N-phenylmaleimide and 
N-(2,4,6-tribromophenyl)maleimide monomers. 
Into a 1 liter, 4 neck round-bottom flask equipped with a stirrer, 
condenser, thermometer, and addition tube, and under a blanket of 
nitrogen, was charged 319 g of Polyol A. After heating Polyol A to 
110.degree. C. and maintaining that temperature for about 30 minutes, the 
following monomer charge was added over a 2-hour period to give a 
milk-white dispersion. 
______________________________________ 
Monomer Charge 
Ingredient Amount (g) 
______________________________________ 
Styrene 53.7 
N--phenylmaleimide 44.7 
Tribromophenylmaleimide 
21.1 
Toluene 50.0 
Tetrahydrofuran 20.0 
AIBN 3.0 
Polyol A 159.0 
______________________________________ 
Upon completion of the addition, the dispersion was held at 110.degree. C. 
for 30 minutes, then the reaction mixture was stripped for 2.5 hours at 
90.degree. C. and 1 mm Hg to yield a stable polymer polyol dispersion. The 
polymer polyol dispersion was found to have a viscosity of 3,930 cps 
(Brookfield cone and plate viscometer spindle #CP-52, 2.5 rpm @26.degree. 
C.) and a solids content by hexane extraction of 22.2%. 
EXAMPLE 7 
This example demonstrates the preparation of a 
styrene/maleimide/acrylonitrile graft terpolymer dispersion of the 
invention. 
Into a 1 liter, 4 neck round-bottom flask equipped with a stirrer, 
condenser, thermometer, and addition tube, and under a blanket of 
nitrogen, was charged 534 g of Polyol A. After heating Polyol A to 
110.degree. C. and maintaining that temperature for about 30 minutes, the 
following monomer charge was added over a 2-hour period to give a 
milk-white dispersion. 
______________________________________ 
Monomer Charge 
Ingredient Amount (g) 
______________________________________ 
Styrene 94.0 
Maleimide 26.0 
Acrylonitrile 80.0 
Toluene 50.0 
AIBN 5.0 
Polyol A 266.0 
______________________________________ 
Upon completion of the addition, the dispersion was held at 110.degree. C. 
for 30 minutes, then the reaction mixture was stripped for 2.5 hours at 
90.degree. C. and 1 mm Hg to yield a stable polymer polyol dispersion. The 
polymer polyol dispersion was found to have a viscosity of 22,000 cps 
(Brookfield cone and plate viscometer spindle #CP-52, 2.5 rpm @ 26.degree. 
C.) and a solids content by hexane extraction of 24.0%. 
EXAMPLE 8 
This example demonstrates the preparation of a 
styrene/N-phenylmaleimide/acrylonitrile graft terpolymer dispersion of the 
invention. 
Into a 1 liter, 4 neck round-bottom flask equipped with a stirrer, 
condenser, thermometer, and addition tube, and under a blanket of 
nitrogen, was charged 1,072 g of Polyol A. After heating Polyol A to 
110.degree. C. and maintaining that temperature for about 30 minutes, the 
following monomer charge was added over a 2-hour period to give a 
milk-white dispersion. 
______________________________________ 
Monomer Charge 
Ingredient Amount (g) 
______________________________________ 
Styrene 200.0 
N--phenylmaleimide 
40.0 
Acrylonitrile 160.0 
Toluene 40.7 
AIBN 10.0 
Polyol A 530.0 
______________________________________ 
Upon completion of the addition, the dispersion was held at 110.degree. C. 
for 30 minutes, then the reaction mixture was stripped for 2.5 hours at 
90.degree. C. and 1 mm Hg and passed through a wiped film evaporator at 
150.degree. C. and 5 torr. to yield a stable polymer polyol dispersion. 
The polymer polyol dispersion was found to have a viscosity of 3,110 cps 
(Brookfield cone and plate viscometer spindle #CP-52, 5.0 rpm @ 26.degree. 
C.) and a solids content by hexane extraction of 22.5%. The resulting 
styrene/N-phenylmaleimide/acrylonitrile terpolymer dispersion was diluted 
to a 20% solids level with Polyol A, and after dilution had a viscosity of 
2,100 cps. 
EXAMPLE 9 
This example demonstrates the preparation of another 
styrene/N-phenylmaleimide/acrylonitrile graft terpolymer dispersion of the 
invention. 
Into a 1 liter, 4 neck round-bottom flask equipped with a stirrer, 
condenser, thermometer, and addition tube, and under a blanket of 
nitrogen, was charged 1,070 g of Polyol A. After heating Polyol A to 
110.degree. C. and maintaining that temperature for about 30 minutes, the 
following monomer charge was added over a 2-hour period to give a 
milk-white dispersion. 
______________________________________ 
Monomer Charge 
Ingredient Amount (g) 
______________________________________ 
Styrene 200.0 
N--phenylmaleimide 
80.0 
Acrylonitrile 120.0 
Toluene 80.0 
AIBN 10.0 
Polyol A 530.0 
______________________________________ 
Upon completion of the addition, the dispersion was held at 110.degree. C. 
for 30 minutes, then the reaction mixture was stripped for 2.5 hours at 
90.degree. C. and 1 mm Hg and passed through a wipe film evaporator to 
yield a stable polymer polyol dispersion. The polymer polyol dispersion 
was found to have a viscosity of 4,030 cps (Brookfield cone and plate 
viscometer spindle #CP-52, 5.0 rpm @ 26.degree. C.) and a solids content 
by hexane extraction of 23.3%. The resulting 
styrene/N-phenylmaleimide/acrylonitrile terpolymer dispersion was 
recovered and diluted to a 20% solids level with Polyol A. 
EXAMPLE 10 
This example demonstrates the preparation of a 
styrene/N-phenylmaleimide/maleic anhydride graft terpolymer dispersion of 
the invention. 
Into a 1 liter, 4 neck round-bottom flask equipped with a stirrer, 
condenser, thermometer, and addition tube, and under a blanket of 
nitrogen, was charged 319 g of Polyol A. After heating Polyol A to 
110.degree. C. and maintaining that temperature for about 30 minutes, the 
following monomer charge was added over a 2-hour period to give a 
milk-white dispersion. 
______________________________________ 
Monomer Charge 
Ingredient Amount (g) 
______________________________________ 
Styrene 50.3 
N--phenylmaleimide 
50.2 
Maleic Anhydride 19.0 
Toluene 50.0 
AIBN 3.0 
Polyol A 159.0 
______________________________________ 
Upon completion of the addition, the dispersion was held at 110.degree. C. 
for 30 minutes, then the reaction mixture was stripped for 2.5 hours at 
90.degree. C. and 1 mm Hg to yield a stable polymer polyol dispersion. The 
polymer polyol dispersion was found to have a viscosity of 2,750 cps 
(Brookfield cone and plate viscometer spindle #CP-52, 2.5 rpm @ 26.degree. 
C.) and a solids content by hexane extraction of 27.5%. The resulting 
styrene/N-phenylmaleimide/maleic anhydride terpolymer dispersion was 
diluted to a 20% solids level with Polyol A, and after dilution had a 
viscosity of 1,220 cps. 
EXAMPLE 11 
This example demonstrates the preparation of a 
styrene/tribromophenylmaleimide/maleic anhydride graft terpolymer 
dispersion of the invention. 
Into a 1 liter, 4 neck round-bottom flask equipped with a stirrer, 
condenser, thermometer, and addition tube, and under a blanket of 
nitrogen, was charged 319 g of Polyol A. After heating Polyol A to 
110.degree. C. and maintaining that temperature for about 30 minutes, the 
following monomer charge was added over a 2-hour period to give a 
milk-white dispersion. 
______________________________________ 
Monomer Charge 
Ingredient Amount (g) 
______________________________________ 
Styrene 56.3 
Tribromophenylmaleimide 
13.3 
Maleic Anhydride 49.9 
Toluene 50.0 
AIBN 3.0 
Polyol A 159.0 
______________________________________ 
Upon completion of the addition, the dispersion was held at 110.degree. C. 
for 30 minutes, then the reaction mixture was stripped for 2.5 hours at 
90.degree. C. and 1 mm Hg to yield a stable polymer polyol dispersion. The 
polymer polyol dispersion was found to have a viscosity of 3,850 cps 
(Brookfield cone and plate viscometer spindle #CP-52,2.5 rpm @ 26.degree. 
C.) and a solids content by hexane extraction of 26.8%. The resulting 
styrene/tribromophenylmaleimide/maleic anhydride terpolymer dispersion was 
diluted to a 20% solids level with Polyol A, and after dilution had a 
viscosity of 1,570 cps. 
EXAMPLE 12 
This example demonstrates the preparation of a 
styrene/N-phenylmaleimide/vinyl acetate graft terpolymer dispersion of the 
invention. 
Into a 1 liter, 4 neck round-bottom flask equipped with a stirrer, 
condenser, thermometer, and addition tube, and under a blanket of 
nitrogen, was charged 638 g of Polyol A. After heating Polyol A. to 
110.degree. C. and maintaining that temperature for about 30 minutes, the 
following monomer charge was added over a 2-hour period to give a 
milk-white dispersion. 
______________________________________ 
Monomer Charge 
Ingredient Amount (g) 
______________________________________ 
Styrene 106.5 
N--phenylmaleimide 
88.5 
Vinyl acetate 44.0 
Toluene 100.0 
AIBN 4.0 
Polyol A 318.0 
______________________________________ 
Upon completion of the addition, the dispersion was held at 110.degree. C. 
for 30 minutes, then the reaction mixture was stripped for 2.5 hours at 
90.degree. C. and 1 mm Hg to yield a stable polymer polyol dispersion. The 
polymer polyol dispersion was found to have a viscosity of 1,730 cps 
(Brookfield cone and plate viscometer spindle #CP-52, 2.5 rpm @ 26.degree. 
C.) and a solids content by hexane extraction of 18.2%. 
COMATIVE EXAMPLE 
This example demonstrates the preparation of a styrene/acrylonitrile graft 
copolymer dispersion for flame retardancy comparison tests with the 
maleimide copolymer dispersions according to this invention. 
Into a 1 liter, 4 neck round-bottom flask equipped with a stirrer, 
condenser, thermometer, and addition tube, and under a blanket of 
nitrogen, was charged 373 g of a glycerin, propylene oxide, ethylene oxide 
adduct containing about 13% ethylene oxide and having a hydroxyl number of 
56. After heating Polyol A to 110.degree. C. and maintaining that 
temperature for about 30 minutes, the following monomer charge was added 
over a 2-hour period to give a milk-white dispersion. 
______________________________________ 
Monomer Charge 
Ingredient Amount (g) 
______________________________________ 
Styrene 122.3 
Acrylonitrile 120.0 
AIBN 6.1 
Polyol A 187.5 
______________________________________ 
Upon completion of the addition, the dispersion was held at 110.degree. C. 
for 30 minutes, then the reaction mixture was stripped for 2.5 hours at 
90.degree. C. and 1 mm Hg to yield a stable polymer polyol dispersion. The 
polymer polyol dispersion was found to have a viscosity of 5,780 cps 
(Brookfield cone and plate viscometer spindle #CP-52, 2.5 rpm @ 26.degree. 
C.) and a solids content by hexane extraction of 32.2%. The resulting 
styrene/acrylonitrile copolymer dispersion was recovered and diluted to 
20% solids with Polyol A. 
The following data present a flame retardancy comparison between a 
styrene/N-phenylmaleimide graft copolymer dispersion of the subject 
invention (Example 1) and the prior art (Comparative Example). The prior 
art copolymer dispersion is a styrene/acrylonitrile dispersion prepared 
according to the procedure of the preceding Comparative Example. 
The dispersion of the prior art employs a styrene/acrylonitrile copolymer. 
In contrast, the dispersion of the present invention contains a 
styrene/N-phenylmaleimide copolymer and contains no acrylonitrile. The 
polyurethane foams were separately prepared by charging the amounts of 
polyol, water catalysts, silicone surfactant, and flame retardant compound 
indicated into a one-liter cylindrical container equipped with a 
mechanical stirrer. The mixture was stirred for about 30 seconds at 5,000 
to 6,000 rpm and the indicated amount of polyisocyanate was introduced 
into the container with stirring for about 10 seconds. The content of the 
container was then immediately poured into a cardboard cake box and the 
foam was allowed to rise. After the foam rise was completed, the foam was 
allowed to cure at room temperature for about one week. 
The flame retardancy test data were determined according to the State of 
California, Department of Consumer Affairs, Bureau of Home Furnishings, 
North Highlands, Calif., Technical Bulletin 117 (January, 1980), Section 
A, Part I, "Resilient Cellular Materials" (hereinafter referred to as 
"California No. 117, A.I."). 
______________________________________ 
Polyol of 
Comparative 
Example Example 1 
Prior Art 
Invention Invention 
______________________________________ 
Formulation, pbw 
Polyol (20% wt. solids) 
100 100 100 
Thermolin 101.sup.1 
9.0 9.0 5.0 
Water 4.0 4.0 4.0 
L-5810.sup.2 surfactant 
0.75 0.75 0.75 
NIAX A-1.sup.3 catalyst 
0.15 0.15 0.15 
T-9.sup.4 catalyst 
0.11 0.11 0.11 
Methylene chloride 
2.0 2.0 2.0 
Toluene diisocyanate 
50 50 50 
Flame Retardancy.sup.5 
Average char length (in) 
6.3 3.8 5.0 
Average after flame (sec) 
9.2 2.0 1.6 
______________________________________ 
.sup.1 tetrakis(2chloroethyl)ethylene diphosphate, Olin Corp. 
.sup.2 silicon surfactant, Union Carbide Corporation 
.sup.3 amine catalyst, Union Carbide Corporation 
.sup.4 organo tin catalyst, Air Products and Chemicals, Inc. 
.sup.5 California 117 A.I., nonaged foam samples 
It will be seen from the above that the absence of acrylonitrile and the 
presence of N-phenylmaleimide in the copolymer dispersion of the invention 
results in foams which exhibit flame retardancy superior to that of the 
prior art. 
Examples 13-19 are shown in following Table I which sets forth the 
ingredients and amounts thereof used to prepare additional foams of the 
invention following substantially the foam preparation procedure described 
above. 
TABLE I 
__________________________________________________________________________ 
POLYURETHANE FOAM 
FORMATION AND FIRE RETARDANCY DATA 
Example No. 
13 14 15 16 17 18 19 
Polyol of Example No. 
8 8 8 8 9 9 9 
__________________________________________________________________________ 
Ingredients pbw 
Polyol 100 100 100 100 100 100 100 
Thermolin.sup.1 101 
7.0 8.0 9.0 12.0 
7.0 8.0 12.0 
Water 4.0 4.0 4.0 4.0 4.0 4.0 4.0 
L-5810.sup.2 
0.75 
0.75 
0.75 
0.75 
0.75 
0.75 
0.75 
Surfactant 
NIAX A-1.sup.3 
0.15 
0.15 
0.15 
0.15 
0.15 
0.15 
0.15 
Catalyst 
T-9.sup.4 Catalyst 
0.1 0.1 0.1 0.1 0.1 0.1 0.1 
Methylene 2.0 2.0 2.0 2.0 2.0 2.0 2.0 
Chloride 
Toluene 50 50 50 50 50 50 50 
Diisocyanate 
Flame Retardancy.sup.5 
Char length 
4.6 4.8 5.1 3.5 1.8 2.5 2.3 
Ave. (in.) 
Afterflame 
9 16 8.4 1.8 4.5 2.8 2.3 
Ave. (sec.) 
__________________________________________________________________________ 
.sup.1 tetrakis(2chloroethyl)ethylene diphosphate, Olin Corp. 
.sup.2 silicon surfactant, Union Carbide Corporation 
.sup.3 amine catalyst, Union Carbide Corporation 
.sup.4 organo tin catalyst, Air Products and Chemicals, Inc. 
.sup.5 California 117 A.I., nonaged foam samples 
It will be evident from the foregoing that various modifications can be 
made to this invention. Such, however, are considered as being within the 
scope of the invention.