Abstract A method for the grafting of alpha,beta unsaturated carboxyic acids or anhydrides onto polypropylene is disclosed. The process comprises admixing polypropylene in melt processing apparatus with 0.01 to 5% by weight of at least one of the acid and anhydride and 0.01 to 2% by weight of an organic peroxide, and extruding and recovering the grafted polypropylene. The apparatus is a twin screw extruder comprising a pair of elongated communicating barrels with parallel adjacent rotatable screws located therein, the screws having flights that are in a non-intermeshing relationship. The method results in the production of grafted polypropylene that exhibits superior adhesive properties, compared with grafted polypropylene formed in twin screw extruders having intermeshing screws. The grafted polypropylene may be used in adhesive formulations.
A method for the grafting of alpha,beta-unsaturated acids and anhydrides onto polypropylene comprising the steps of: (a) admixing polypropylene in melt processing apparatus with 0.01 to 5% by weight of at least one of alpha,beta unsaturated carboxylic acid and alpha,beta-unsaturated carboxylic anhydride and 0.01 to 2% by weight of an organic peroxide at a temperature above the melting point of the polypropylene, said melt processing apparatus being a twin-screw extruder comprised of a pair of elongated communicating barrels with parallel adjacent rotatable screws located therein, said screws having flights thereon that are in a non-intermeshing relationship; and (b) extruding and recovering grafted polypropylene.
Claim 2
Independent Claim
103 words
A method for the grafting of alpha,beta-unsaturated acids and anhydrides onto polypropylene comprising the steps of: (a) admixing polypropylene in melt processing apparatus with 0.01 to 5% by weight of at least one of alpha,beta unsaturated carboxylic acid and alpha,beta-unsaturated carboxylic anhydride and 0.01 to 2% by weight of an organic peroxide at a temperature above the melting point of the polypropylene, said melt processing apparatus being a twin-screw extruder comprised of a pair of elongated communicating barrels with parallel adjacent rotatable screws located therein, said screws having flights thereon that are in a non-intermeshing relationship; and (b) extruding and recovering grafted polypropylene.
Claim 3
Dependent Claim
21 words
The method of Claim 1 in which the polypropylene is grafted with at least one of maleic acid and maleic anhydride.
Claim 4
Dependent Claim
22 words
The method of Claim 2 in which the amount of maleic anhydride is in the range of 0.1 to 0.4% by weight.
Claim 5
Independent Claim
25 words
The method of any one of Claims 1-3 in which the amount of organic peroxide is in the range of 0.05 to 0.5% by weight.
Claim 6
Independent Claim
29 words
The method of any one of Claims 1-4 in which the grafted polypropylene is treated with an aqueous solution of sodium hydroxide or has an alkaline material added thereto.
Claim 7
Dependent Claim
19 words
The method of Claim 5 in which the grafted polypropylene is treated with an aqueous solution of sodium hydroxide.
Claim 8
Dependent Claim
16 words
The method of Claim 5 in which the grafted polypropylene has an alkaline material added thereto.
Claim 9
Independent Claim
27 words
The method of any one of Claims 1-7 in which at least one of un-grafted polypropylene and a toughening agent is subsequently blended with the grafted polypropylene.
Claim 10
Independent Claim
17 words
The method of any one of Claims 1-8 in which the polypropylene is a homopolymer of propylene.
Claim 11
Independent Claim
50 words
The method of any one of Claims 1-8 in which the polypropylene is selected from block copolymers of propylene and ethylene in which the ethylene content is less than 25% by weight and random copolymers of propylene and ethylene in which the ethylene content is less than 8% by weight.
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