A process for preparing hydroxy phosphonic acid ester polyols by reacting an alkenyl phosphonic acid with an alkylene oxide and the reaction of the resulting hydroxy phosphonic acid ester polyols with polyisocyanates to form polyurethanes is described.

This invention relates to a process for preparing novel, flame retardant 
polyurethanes by using hydroxy alkenyl phosphonic acid ester polyols as 
fire retarding additives in the reaction of polyols with polyisocyanates 
to form thermosetting polyurethanes. The alkenyl phosphonic acid ester 
polyols are obtained from the reaction of an alkenyl phosphonic acid, such 
as isopropenyl phosphonic acid with an alkylene oxide, such as propylene 
oxide. The hydroxyalkenyl phosphonic acid ester polyols are also good 
compatibilizing agents for conventional polyol mixtures and fluorocarbon 
blowing agents used in the production of polyurethane foams. 
Although various phosphorus containing organic molecules have been used as 
fire retarding additives in various polymeric materials, the phosphorous 
containing polyols embodied in this invention have not been previously 
disclosed as flame retardant materials for use in the manufacture of 
thermosetting polyurethanes. 
We have discovered that polyols obtained from the reaction of alkylene 
oxides, such as propylene oxide, with an alkenyl phosphonic acid, such as 
isopropenyl phosphonic acid, can be utilized along with other conventional 
polyols as fire retardants in the synthesis of polyurethanes and they can 
also be used as compatibilizing agents for fluorocarbon blowing agents in 
the formation of polyurethane foams. 
The following equation illustrates the formation of the flame retardant 
polyols of this invention. 
##STR1## 
wherein n represents a number of from 1 to 50 in the polyol (A) and R is 
an alkyl group having from 1 to 10 carbon atoms or a phenyl group, R' is 
an alkylene group having from 2 to 4 carbon atoms and R" independently 
represents hydrogen or an alkyl group having from 1 to 10 carbon atoms. 
A typical polyol of the type (A) is obtained from the reaction of 
isopropenyl phosphonic acid with propylene oxide and the resulting polyol 
has been found to be compatible with short- and long-chain polyols and the 
mixtures of these polyols, upon reaction with polyisocyanates, result in 
polyurethane polymer formation. The resulting polyurethane polymers have 
been found to have a higher degree of fire resistance compared to the 
polyurethane polymers obtained without the use of the alkenyl phosphonic 
acid ester polyols of this invention. 
The alkylene oxides useful in the preparation of the alkenyl phosphonic 
acid ester polyols include ethylene oxide, propylene oxide, tetramethylene 
oxide, styrene oxide, the glycidyl ether of phenolics such as Bisphenol-A, 
cyclohexene oxide, vinyl cyclohexene dioxide, and the like. Most preferred 
are ethylene oxide propylene oxide, and tetramethylene oxide. 
Alkenyl phosphonic acids which are useful in the preparation of the flame 
retardant polyols embodied in this invention include isopropenyl 
phosphonic acids, vinyl phosphonic acid, phenethylene phosphonic acid and 
the like. Most preferred is isopropenyl phosphonic acid because of its 
ready availability. 
Polyols, in addition to the flame retardant polyols of this invention, 
which can be used in the formation of flame retardant polyurethanes 
include those having at least two hydroxyl groups per molecule and having 
equivalent weights falling in the range of from 20 to 5000. Specific 
polyols include butane diol, cyclohexane dimethanol, tripropylene glycol, 
amide diols, urethane diols, polyether polyols such as poly 
(tetramethylene ether) diols, poly (propylene ether) polyols, polyester 
polyols, and the like. 
Polyhydroxy polyethers are suitable polyols and preferably those having at 
least 2 hydroxyl groups per molecule. Polyhydroxy polyethers can be 
prepared by polymerization of epoxides such as ethylene oxide, propylene 
oxide, butylene oxide, tetrahydrofuran, styrene oxide, or epichlorohydrin 
either on their own or by chemical addition to other materials such as 
ethylene glycol, propylene glycol, trimethylol propanes and 4,4'-dihydroxy 
diphenyl propane. Sucrose polyethers also may be used. Polybutadienes 
having hydroxyl groups as well as other known hydroxyl containing vinyl 
addition polymerized polymers can be used. 
According to the present invention, hydroxyl containing polyesters, 
polythioethers, polyacetals, polycarbonates or polyesteramides of the 
types known for the formation of polyurethanes may also be used. 
The polyisocyanates useful in this invention include organic isocyanates 
having at least two isocyanate groups per molecule. The polyisocyanates 
can be of low, high or intermediate molecular weight and can be any of a 
wide variety of organic polyisocyanates including ethylene diisocyanate, 
trimethylene diisocyanate, dodecamethylene diisocyanate, hexamethylene 
diisocyanate, hexamethylene diisocyanate trimer, tetraethylene 
diisocyanate, pentamethylene diisocyanate, propylene-1,2-diisocyanate, 
2,3-dimethyl tetramethylene diisocyanate, butylene-1,2-diisocyanate, 
butylene-1,3-diisocyanate, 1,4-diisocyanato cyclohexane, 
cyclopentene-1,2-diisocyanate, p-phenylene diisocyanate, 1-methyl 
phenylene-1,2-diisocyanate, naphthalene-1,4-diisocyanate, toluene 
diisocyanate, diphenyl-4,4'-diisocyanate, benzene-1,2,4-triisocyanate, 
xylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, 4,4'-diphenylene 
methane diisocyanate, 4,4'-diphenylene propane diisocyanate, 
1,2,3,4-tetraisocyanato butane, butane-1,2,3-triisocyanate, polymethylene 
polyphenyl isocyanate, and other polyisocyanates having an isocyanate 
functionality of at least two more fully disclosed in U.S. Pat. Nos. 
3,350,362 and 3,382,215. Polyisocyanates which are polymeric in nature 
including isocyanate prepolymers of all types are included in this 
invention. 
In the preparation of the polyurethanes of this invention the hydroxyl 
equivalent to isocyanate equivalent ratios can be in the range of 0.85:1 
to 1:10, respectively. When more than one isocyanate equivalent per 
hydroxyl equivalent is used, thermosetting polyurethane polymers result. 
In the formation of polyurethanes in accordance with this invention 
catalysts which are known to catalyze polyurethane formation can be used. 
Such catalysts include tertiary amines, organotin carboxylates, metal 
salts such as lithium chloride, zinc carboxylates, iron acetyl acetonate, 
tetraalkyl ammonium halides and the like. Furthermore, because the alkenyl 
phosphonic acid ester polyols contain vinyl carbon-to-carbon unsaturation, 
the vinyl function can be used for further copolymerization with other 
vinyl monomers such as styrene, acrylates, methacrylates, acrylonitrile, 
hydroxy alky acrylates or methacrylates, and the like. 
It has further been found that the alkenyl phosphonic acid ester polyols of 
this invention act as excellent compatibilizing agents. Thus, small 
amounts of the polyols of formula (A) above compatibilize mixtures of 
polyterephthalic ester polyols obtained from the transesterification of 
dimethyl terephthalate with low molecular weight glycols and the 
fluorocarbon blowing agent used for the production of cellular 
polyurethane polymers. The polyterephathalic ester polyols are more fully 
described in U.S. Pat. No. 3,647,759. The lack of compatibility of these 
polyterephathalic ester polyols with fluorocarbon blowing agents is more 
fully described in U.S. Pat. No. 4,444,916. 
Other additives such as plasticizers, fillers, pigments, reinforcing 
fibers, and the like which are known to those skilled in the art can be 
included in the cellular and non-cellular polyurethanes which can be 
produced within the scope of this invention.

This invention is further illustrated in the following representative 
examples. 
EXAMPLE I 
In a reactor equipped with a mechanical stirrer and a reflux condenser were 
placed 503 g of isopropenyl phosphonic acid and then 475.2 g of propylene 
oxide were added slowly under constant stirring. An exothermic reaction 
occurred. The reactor was cooled and the temperature was maintained near 
room temperature. A part (567 g) of the resulting viscous liquid was 
transferred to an autoclave and was charged with 303 g of propylene oxide. 
The resulting mixture was allowed to react at 100 degrees C. for 
approximately two hours. The resulting viscous liquid was degassed under 
reduced pressure on a rotary evaporator. The clear liquid product was 
analyzed and found to have a hydroxyl number of 253 and an acid value of 
1. This isopropenyl phosphonic acid polyol was used in subsequent 
Examples. 
EXAMPLE 2 
This experiment shows the use of the isopropenyl phosphonic acid ester 
polyol of Example 1 as a compatibilizing agent. In a one-ounce jar were 
placed 10 g of a diethylene glycol blend of terephthalic ester polyol 
having a hydroxyl number of 477 (commercially available from Chardinol 
Corp. as Chardol 560) and 2 g of the polyol described in Example 1. The 
resulting homogeneous solution was mixed vigorously with 4 g of 
fluorocarbon blowing agent (Freon F11B from DuPont 
Co.-trichlorofluoromethane) to give a homogeneous solution. The closed jar 
was kept at room temperature undistured for two hours during which time no 
separation occurred. An additional 2.3 g of the Freon were added and the 
mixed homogeneous solution was kept at room temperature for another two 
hours during which time no phase separation occurred. 
EXAMPLE 3 
This is a comparative example outside the scope of this invention. The 
process of Example 2 was followed using 10.1 g of the diethylene glycol 
blend of terephthalic ester polyol and 4 g of the fluorocarbon blowing 
agent. The vigorously stirred mixture was kept in the closed jar at room 
temperature and phase separation was observed within five minutes of 
standing undisturbed. 
EXAMPLE 4 
The polyol of Example 1 (15 g) was mixed with 0.3 g of 
N,N',N-tris(dimethylamine propyl) hexahydrotriazine, 0.03 g of dibutyltin 
dilaurate, 0.4 g of silicone surfactant (Dow Corning DC-193) and 5 grams 
of fluorinated hydrocarbon blowing agent (Freon F11B). The resulting 
solution was mixed rapidly with 20 g of carbodiimide group containing 
liquid methylene bis(phenyl isocyanate) (NCO equivalent weight 144). Rapid 
reaction occurred to give a foam having the following formation 
characteristics: cream time of 30 seconds, rise time of 62 seconds and 
tack-free time of 80 seconds. This foam was postcured at 100 degrees C. 
for 10 minutes to give a product which was found to have a density of 2.3 
pounds/cubic foot and was also found to be non-flammable. 
EXAMPLE 5 
The procedure of Example 4 was followed using 12 g of the terephthalic 
ester polyol of Example 2, 5 g of the polyol of Example 1, 0.35 g of the 
tertiary amine catalyst, 0.4 g of the silicone surfactant, 5 g of the 
fluorocarbon blowing agent and the mixture was treated with 26 g of the 
polyisocyanate. Foaming occurred rapidly giving a cream time of 20 
seconds, a rise time of 38 seconds and a tack free time of 42 seconds. The 
final foam had a non-friable surface, a density of 1.95 pounds/cubic foot 
and the compressive strength was 18 psi. The foam was found to be 
self-extinguishing. 
EXAMPLE 6 
The procedure of Example 4 was followed using 12 g of the poly terephthalic 
ester polyol (hydroxyl number of 350, 4.0 g of the polyol of Example 1, 
0.3 g of the tertiary amine catalyst, 0.02 g of t-butyl peroctoate, 0.4 g 
of silicone surfactant, 5 g of blowing agent and 25 g of polyisocyanate 
based on methylene bis-(phenyl isocyanate) (functionality of 2.3). The 
foam as it formed was found to have a cream time of 32 seconds, a rise 
time of 50 seconds and a tack free time of 60 seconds. The foam was 
postcured at 100 degrees C. for five minutes. No shrinkage was noticed and 
the surface was non-friable. The foam was self-extinguishing and had a 
density of 1.92 pounds/cubic foot and a compressive strength of 19 psi. 
EXAMPLE 7 
The procedure of Example 4 was followed using 11 g of polyterephthalic 
ester polyol (hydroxyl No. 447), 5 g of the polyol of Example 1, 0.35 g of 
the tertiary amine catalyst, 0.4 g of silicone surfactant, 7 g of talc 
filler, 5.4 g of fluorocarbon blowing agent and 25 g of the 
polyisocyanate. The foam had a cream time of 22 seconds, a rise time of 37 
seconds and a tack free time of 43 seconds. The final polymer foam was 
found to be self-extinguishing to almost non-flammable. The final foam had 
a density of 2.3 pounds per cubic foot and a compressive strength of 19 
psi. 
EXAMPLE 8 
A solution of 15 g of propylene glycol, 7 g of dipropylene glycol, 18 g of 
poly (propylene ether) triol (molecular weight of about 5500), 6 g of the 
polyol of example 1 and 0.4 g of the tertiary amine catalyst, was degassed 
on a rotary evaporator under reduced pressure. This solution was mixed 
rapidly with 105 g of degassed liquid methylene bis (phenyl isocyanate) 
and poured into a hot mold at 90 degrees C. The mold was prepared with two 
parallel glass plates which were coated with a silicone mold release agent 
and spaced apart by 1/8 inch spacers. Polymerization occurred within a 
minute at room temperature to give an opaque white polymer which was 
placed in an oven at 100 degrees C. for 30 minutes for post cure. The 
resulting polymer sheet showed a notched izod impact strength (ASTM D-256) 
of 1.0 foot pound/inch of notch and a heat distortion temperature (ASTM 
D-648) of 105 degrees C.