Toughened Blends of Cellulose Esters with Polyacetals

1 . A thermoplastic composition comprising:

a) 87 to 30 weight percent of a polyacetal homopolymer or of a polyacetal copolymer, or of a combination of these;

b) 10 to 60 weight percent of one or more cellulose ester(s) of C1 to C6 alkyl carboxylic acids; and

c) 3-15 weight percent of at least one toughener, wherein each weight percent is based on the total weight of the thermoplastic composition.

2 . The composition of claim 1 , wherein the toughener is selected from the group consisting of:

i) a thermoplastic elastomer selected from the group consisting of thermoplastic polyurethane, copolyetheramide, and copolyetherester and having a soft segment glass transition temperature of less than −20° C.;

ii) an ethylene copolymer of the formula E/X,

wherein E comprises 60-90 weight percent, and X comprises 10-40 weight percent, of the ethylene copolymer;

iii) an ethylene copolymer of the formula E/X/Y,

wherein E comprises 40-89.5 weight percent, X comprises 10-40 weight percent, and Y comprises 0.5-20 weight percent, of the ethylene copolymer,

and a combination of these,

wherein

E is the radical formed from ethylene,

X is one or more radicals formed from CH 2 ═CH(R 1 )—C(O)—OR 2 ,

wherein R 1 is H, CH 3 or C 2 H 5 , (preferably H or CH 3 , and most preferably H)R 2 is an alkyl group having 1-8 carbon atoms, vinyl acetate or a combination of these, and

Y is a radical formed from monomers selected from the group consisting of CH 2 ═CH(R 1 )—C(O)—OR 3 ,

wherein R 3 is glycidyl, and R 1 is R 1 is H, CH 3 or C 2 H 5 , acrylonitrile, methacrylonitrile, styrene, and carbon monoxide.

3 . The composition of claim 1 , wherein the one or more cellulose ester is selected from the group consisting of cellulose acetate, cellulose propionate, cellulose butyrate, and a combination of these.

4 . The composition of claim 1 , wherein the one or more cellulose ester has a glass transition of between 100 and 225° C.

5 . The composition of claim 1 , wherein the polyacetal is a homopolymer.

6 . The composition of claim 1 , wherein the polyacetal has a number average molecular weight of from 20,000 to 100,000.

7 . The composition of claim 1 , wherein the polyacetal has a melt flow rate of 0.1 to 10.0 grams/10 minutes.

8 . The composition of claim 1 , wherein the polyacetal is a copolymer derived from copolymerization of a comonomer selected from the group consisting of alkylene oxides of 2-12 carbon atoms.

9 . An article made from the composition of claim 1 .

10 . The article of claim 9 comprising a housing or a sprocket.