Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2000-11-02
2003-02-11
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S113000, C522S116000, C522S120000, C522S121000, C522S126000, C522S127000, C522S133000, C522S134000, C522S136000, C522S149000, C522S150000, C522S157000, C522S161000, C244S232000, C244S232000, C244S232000, C244S198000, C244S198000
Reexamination Certificate
active
06518327
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an irradiation process for making graft copolymers of an olefin polymer material.
BACKGROUND OF THE INVENTION
Polyolefin graft copolymers can be made by any one of various methods, including forming active sites on the polyolefin either in the presence of the grafting monomers, or followed by treatment with the monomer. The grafting sites can be produced by treatment with a peroxide or other chemical compound that is a free radical polymerization initiator, or by irradiation with high energy ionizing radiation. The free radicals produced in the olefin polymer as a result of the chemical or irradiation treatment act as initiators for the polymerization of the monomer, as well as active sites for grafting. For example, U.S. Pat. No. 5,411,994 discloses making polyolefin graft copolymers by irradiating olefin polymer particles and treating with a vinyl monomer in liquid form. A non-oxidizing environment is maintained throughout the process.
Various additives have been used to modify characteristics of graft copolymers such as the morphology of the polymer particles. For example, U.S. Pat. No. 5,916,974 discloses graft polymerizing in the presence of an organic peroxide and a polymerization rate modifier (PRM) to increase the polymerization induction time on the polymer surface, consequently facilitating monomer diffusion into the interior of the polymer particles so that surface polymerization of the monomer is inhibited. Suitable PRMs include sulfur, benzoquinone and its derivatives, and hydroxylamine and its derivatives. The PRM has no significant impact on the number average and weight average molecular weight of the product.
There is a need for a process for controlling the molecular weight of the polymerized monomer side chains of polyolefin graft copolymers made from irradiated polyolefins so that low molecular weight side chains are produced, thereby improving the surface and internal morphology of the graft copolymers and improving processing without adversely affecting the overall physical properties of the graft copolymer.
SUMMARY OF THE INVENTION
The process of this invention for making graft copolymers comprises, in a substantially non-oxidizing atmosphere,
(1) irradiating a particulate olefin polymer material at a temperature of about 100 to about 85° C. with high energy ionizing radiation to produce free radical sites on the olefin polymer material,
(2) treating the irradiated particulate olefin polymer material at a temperature of about 250 to about 90° C. with about 0.5 to about 120 parts per hundred parts of the olefin polymer material of at least one grafting monomer that is capable of being polymerized by free radicals to form side chains on the olefin polymer material, in the presence of about 1 part to about 10,000 parts per million parts of monomer of at least one additive to control the molecular weight of the side chains of the polymerized grafting monomer, selected from the group consisting of (a) at least one hydroxylamine derivative polymerization inhibitor and (b) at least one chain transfer agent selected from the group consisting of (i) thio-substituted aliphatic and aromatic compounds, (ii) halogen-substituted aliphatic and aromatic compounds, (iii) nitro-substituted aliphatic and aromatic compounds, and (iv) aliphatic and aromatic phosphine derivatives, and
(3) simultaneously or successively in optional order, (i) deactivating substantially all residual free radicals in the resultant grafted particulate olefin polymer material, and (ii) removing any unreacted vinyl monomer from the material.
Carrying out the graft polymerization reaction in the presence of at least one hydroxylamine derivative polymerization inhibitor and/or one or more of the specified chain transfer agents produced graft copolymers with low molecular weight side chains. The graft copolymer product is easier to process and has improved internal and surface morphology.
DETAILED DESCRIPTION OF THE INVENTION
The process of this invention for making graft copolymers comprises, in a substantially non-oxidizing atmosphere,
(1) irradiating a particulate olefin polymer material at a temperature of about 100 to about 85° C. with high energy ionizing radiation to produce free radical sites on the olefin polymer material,
(2) treating the irradiated particulate olefin polymer material at a temperature of about 25° C. to about 90° C. with about 0.5 to about 120 parts per hundred parts of the olefin polymer material of at least one grafting monomer that is capable of being polymerized by free radicals to form side chains on the olefin polymer material, in the presence of about 1 part to about 10,000 parts per million parts of monomer of at least one additive to control the molecular weight of the side chains. of the polymerized grafting monomer, selected from the group consisting of (a) at least one hydroxylamine derivative polymerization inhibitor and (b) at least one chain transfer agent selected from the group consisting of (i) thio-substituted aliphatic and aromatic compounds, (ii) halogen-substituted aliphatic and aromatic compounds, (iii) nitro-substituted aliphatic and aromatic compounds, and (iv) aliphatic and aromatic phosphine derivatives, and
(3) simultaneously or successively in optional order, (i) deactivating substantially all residual free radicals in the resultant grafted particulate olefin polymer material, and (ii) removing any unreacted vinyl monomer from the material.
The propylene polymer material that is used as the backbone of the graft copolymer can be:
(1) a crystalline homopolymer of propylene having an isotactic index greater than 80, preferably about 85 to about 99;
(2) a crystalline copolymer of propylene and an olefin selected from the group consisting of ethylene and 4-10 C alpha-olefins, provided that when the olefin is ethylene, the maximum polymerized ethylene content is about 10%, preferably about 4%, and when the olefin is a 4-10 C alpha-olefin, the maximum polymerized content thereof is about 20% by weight, preferably about 16%, the copolymer having an isotactic index greater than 85;
(3) a crystalline terpolymer of propylene and two olefins selected from the group consisting of ethylene and 4-8 C alpha-olefins, provided that the maximum polymerized 4-8 C alpha-olefin content is 20% by weight, preferably about 16%, and, when ethylene is one of the olefins, the maximum polymerized ethylene content is 5% by weight, preferably about 4%, the terpolymer having an isotactic index greater than 85;
(4) an olefin polymer composition comprising:
(a) about 10% to about 60% by weight, preferably about 15% to about 55%, of a crystalline propylene homopolymer having an isotactic index greater than 80, preferably about 85 to about 98, or a crystalline copolymer of monomers selected from the group consisting of (i) propylene and ethylene, (ii) propylene, ethylene and a 4-8 C alpha-olefin, and (iii) propylene and a 4-8 C alpha-olefin, the copolymer having a polymerized propylene content of more than 85% by weight, preferably about 90% to about 99%, and an isotactic index greater than 85;
(b) about 5% to about 25% by weight, preferably about 5% to about 200%, of a copolymer of ethylene and propylene or a 4-8 C alpha-olefin that is insoluble in xylene at ambient temperature; and
(c) about 300% to about 70% by weight, preferably about 400/o to about 65%, of an elastomeric copolymer of monomers selected from the group consisting of (i) ethylene and propylene, (ii) ethylene, propylene, and a 4-8 C alpha-olefin, and (iii) ethylene and a 4-8 C alpha-olefin, the copolymer optionally containing about 0.5% to about 10% by weight of a polymerized diene and containing less than 70% by weight, preferably about 10% to about 60%, most preferably about 12% to about 55%, of polymerized ethylene and being soluble in xylene at ambient temperature and having an intrinsic viscosity, measured in decahydronaphthalene at 135° C., of about 1.5 to about 4.0 dl/g,
wherein the total amount of (b) and (c), based on the total olefin polymer composition,
Dang Vu A.
Phan Tam T. M.
Smith Jeanine A.
Song Cheng Q.
Basell Poliolefine Italia S.p.A.
McClendon Sanza L.
Seidleck James J.
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