US 5,290,875 AGranted

Conjugated diene/monovinylarene block copolymers with multiple tapered blocks

AssigneePhillips Petroleum Company

InventorsGeorge A. Moczygemba, Nathan E. Stacy, Nancy R. Knight

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Abstract

A method for preparing polymodal tapered block copolymers in a polymerization process by sequentially charging: (a) an initiator and monovinylaromatic monomers in the presence of a randomizer; (b) an initiator and monovinylaromatic monomers; (c) a mixture of monovinylaromatic and conjugated diene monomers; (d) a mixture of monovinylaromatic and conjugated diene monomers; (e) an initiator and monovinylaromatic monomers; (f) a mixture of monovinylaromatic and conjugated diene monomers; (g) a mixture of monovinylaromatic and conjugated diene monomers; (h) conjugated diene monomers; and (i) a coupling agent. The copolymers are particularly useful for packaging applications which require good environmental stress crack resistance.

Claims18

Dependent claims

A method of preparing a polymer comprising:

(a) charging into a polymerization zone an initiator and a monovinylaromatic monomer in the presence of a randomizer and allowing polymerization to occur until essentially no free monomer is present;
thereafter
(b) charging into said polymerization zone a monovinylaromatic monomer and an initiator and allowing polymerization to occur until essentially no free monomer is present;
thereafter
(c) charging into said polymerization zone a mixture of monovinylaromatic monomer and conjugated diene monomer and allowing polymerization to occur until essentially no free monomer is present;
thereafter
(d) charging into said polymerization zone a mixture of monovinylaromatic monomer and conjugated diene monomer and allowing polymerization to occur until essentially no free monomer is present;
thereafter
(e) charging into said polymerization zone a monovinylaromatic monomer and an initiator and allowing polymerization to occur until essentially no free monomer is present;
thereafter
(f) charging into said polymerization zone a mixture of monovinylaromatic monomer and conjugated diene monomer and allowing polymerization to occur until essentially no free monomer is present;
thereafter
(g) charging into said polymerization zone a mixture of monovinylaromatic monomer and conjugated diene monomer and allowing polymerization to occur until essentially no free monomer is present;
thereafter
(h) charging into said polymerization zone a conjugated diene monomer and allowing polymerization to occur until essentially no free monomer is present;
and thereafter
(i) charging the reaction mixture with a coupling agent.

14 more elements

Dependencies are inferred from the claim text.