Flame-retardant thermoplastic copolymers based on vinyl phosphonate derivatives grafted onto rubber
AssigneeArco Chemical Technology, L.P.
InventorsRoger A. Grey, Shao H. Guo
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Abstract
Flame-retardant, thermoplastic copolymers and processes for making them are disclosed. The compositions are copolymers of a vinyl aromatic monomer, a vinyl phosphonic acid derivative, and optionally, an unsaturated organic diacid, ester, or anhydride that are grafted onto a rubber. Processes for making polymers having high molecular weight, good mechanical properties, and a high level of evenly distributed, chemically incorporated vinyl phosphonate flame retardant are also disclosed.
Claims14
A flame-retardant polymer composition comprising recurring units of:
- (a) a vinyl aromatic monomer;
- (b) an unsaturated organic diacid, ester, or anhydride;
- (c) a vinyl phosphonic acid derivative selected from the group consisting of vinyl phosphonic acids and vinyl phosphonate mono- and diesters;
- and
- (d) optionally, one or more additional ethylenically unsaturated monomers;
- wherein the composition is grafted onto from about 1 to about 50 wt. % based on the total amount of polymer composition of a rubber selected from the group consisting of polybutadiene, polyisoprene, EPDM rubber, styrene-isoprene copolymers, and styrene-butadiene copolymers;
- and wherein the polymer composition has a number average molecular weight within the range of about 30,000 to about 400,000.
A process for making a flame-retardant polymer composition grafted onto a rubber, said process comprising polymerizing a mixture that contains a vinyl aromatic monomer, a free-radical initiator, and from about 1 to about 50 wt % based on the total amount of polymer composition of a rubber selected from the group consisting of polybutadiene, polyisoprene, EPDM rubber, styrene-isoprene copolymers, and styrene-butadiene copolymers, while continuously adding to the mixture a vinyl phosphonic acid derivative selected from the group consisting of vinyl phosphonic acids and vinyl phosphonate mono- and diesters to produce the flame-retardant polymer composition.
A process for making a flame-retardant polymer composition grafted onto a rubber, said process comprising polymerizing, in an aqueous suspension and in the presence of a phase-transfer catalyst, a vinyl aromatic monomer, from about 1 to about 50 wt % based on the total amount of polymer composition of a rubber selected from the group consisting of polybutadiene, polyisoprene, EPDM rubber, styrene-isoprene copolymers, and styrene-butadiene copolymers, and a relatively water-soluble vinyl phosphonic acid derivative selected from the group consisting of vinyl phosphonic acids and vinyl phosphonate mono- and diesters.
Dependencies are inferred from the claim text.