Compatibilization of hydroxyl-containing fillers and thermoplastic polymers

DETAILED DESCRIPTION I claim: 1.
A process for compatibilizing a hydroxyl group containing inorgaic filler with a thermoplastic polymer having labile atoms which provide sites for the formation of free radicals which comprises mixing said filler and said thermoplastic polymer in the presence of an ethylenically unsaturated carboxylic acid or anhydride and a free radical catalyst under conditions which will generate free radicals on the thermoplastic polymer and which will permit the acid or anhydride to react simultaneously with the thermoplastic polymer and the hydroxyl group containing filler, whereby said acid or anhydride reacts with and couples said thermoplastic polymer and said hydroxyl group containing filler to provide a filled thermoplastic polymer composition.
2.
A process as defined in claim 1 wherein said free radical catalyst is a peroxide compound which will initiate the homopolymerization of maleic anhydride.
3.
A process as defined in claim 1 wherein said free radical catalyst is a peroxide compound which has a half-life of up to about 30 minutes at the temperature at which said mixing occurs.
4.
A process as defined in claim 1 wherein said thermoplastic polymer is a polyolefin.
5.
A process as defined in claim 4 wherein said ethylenically unsaturated carboxylic acid or anhydride is maleic anhydride or maleic acid.
6.
A process according to claim 5 wherein said polyolefin is high density polyethylene.
7.
A process as defined in claim 5 wherein said filler is clay.
8.
A process as defined in claim 5 wherein said filler material and said polyolefin are mixed with from about 2 to 30% by weight of maleic anydride and from about 0.
5 to 10% by weight of a peroxide catalyst.
9.
A process as defined in claim 5 wherein said filler and said thermoplastic polymer are mixed together before being mixed with said ethylenically unsaturated carboxylic acid or anhydride and said free radical catalyst.
10.
A process as defined in claim 5 wherein said hydroxyl group containing filler is glass