POLYMER POLYOLS HAVING IMPROVED QUALITY

1 . A polymer polyol comprising the free-radical polymerization product of:

(A) one or more base polyols;

(B) optionally, one or more preformed stabilizers;

with

(C) one or more ethylenically unsaturated monomers, wherein at least one of said monomers is styrene which contains less than or equal to 1000 ppm of impurities;

in the presence of

(D) at least one free radial polymerization catalyst;

and, optionally,

(E) one or more chain transfer agents.

2 . The polymer polyol of claim 1 , wherein said impurities contain at least on compound which is selected from the group consisting of polystyrene, phenylacetylene and divinylbenzene.

3 . The polymer polyol of claim 1 , wherein said styrene monomer contains less than 750 ppm of impurities.

4 . The polymer polyol of claim 1 , wherein said styrene monomer contains less than or equal to 400 ppm of impurities.

5 . The polymer polyol of claim 1 , wherein (C) said one or more ethylenically unsaturated monomers comprises a mixture of styrene monomer and acrylonitrile.

6 . The polymer polyol of claim 1 , which comprises (B) one or more preformed stabilizers which is a high potency preformed stabilizer, and said stabilizer is present in an amount of at least about 0.25% by weight, based on the total weight of the polymer polyol.

7 . The polymer polyol of claim 1 , wherein said free radical polymerization catalyst is selected from the group consisting of peroxides, persulfates, perborates, percarbonates, azo compounds and mixtures thereof.

8 . The polymer polyol of claim 1 , wherein the solids content ranges from greater than about 20% by weight up to about 75% by weight, based on the total weight of the polymer polyol.

9 . A process for the preparation of a polymer polyol comprising:

(I) free-radically polymerizing

(A) one or more base polyols;

(B) optionally, one or more preformed stabilizers;

with

(C) one or more ethylenically unsaturated monomers, wherein at least one of said monomers is styrene which contains less than or equal to 1000 ppm of impurities;

in the presence of

(D) at least one free radial polymerization catalyst;

and, optionally,

(E) one or more chain transfer agents.

10 . The process of claim 9 , wherein said impurities contain at least one compound which is selected from the group consisting of polystyrene, phenylacetylene and divinylbenzene.

11 . The process of claim 9 , wherein said styrene monomer contains less than 750 ppm of impurities.

12 . The process of claim 9 , wherein said styrene monomer contains less than or equal to 400 ppm of impurities.

13 . The process of claim 9 , wherein (C) said one or more ethylenically unsaturated monomers comprises a mixture of styrene monomer and acrylonitrile.

14 . The process of claim 9 , which comprises (B) one or more preformed stabilizers which is a high potency preformed stabilizer, and said stabilizer is present in an amount of at least about 0.25% by weight, based on the total weight of the polymer polyol.

15 . The process of claim 9 , wherein said free radical polymerization catalyst is selected from the group consisting of peroxides, persulfates, perborates, percarbonates, azo compounds and mixtures thereof.

16 . The process of claim 9 , wherein the solids content ranges from greater than about 20% by weight up to about 75% by weight, based on the total weight of the polymer polyol.

17 . A process for preparing a polyurethane foam, comprising reacting

(1) a polyisocyanate

with

(2) an isocyanate-reactive component comprising the polymer polyol of claim 1 ,

in the presence of

(3) at least one catalyst,

and

(4) at least one blowing agent.

18 . A polyurethane foam comprising the reaction product of

(1) a polyisocyanate,

with

(2) an isocyanate-reactive component comprising the polymer polyol of claim 1 ,

in the presence of

(3) at least one catalyst,

and

(4) at least one blowing agent.