US 4,048,427 AGranted

Preparation of solution polymers

AssigneeThe General Tire & Rubber Company

InventorsIvan Glen Hargis, Russell Anthony Livigni, Sundar Lal Aggarwal

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Abstract

This invention relates to the preparation of solution polymers and rubbers from vinyl monomers using a new catalyst complex of a barium di-tert-alkoxide-hydroxide salt and an organic lithium compound. In particular, homopolymers and copolymers of butadiene with styrene and/or isoprene, prepared with this catalyst, are uniquely characterized by the butadiene units having a low vinyl content (not over about 12%) and a trans-1,4 structure of from about 70 to 81%. Also, the copolymer has a random comonomer sequence distribution. This molecular structure permits elastomers containing little or no styrene to have sufficient stereoregularity to crystallize. Furthermore, the butadiene homopolymer and copolymer with styrene and/or isoprene exhibit a broad molecular weight distribution as well as tack and green-strength which are valuable properties for a rubber to possess when building tires.

Claims4

Dependent claims

A rubbery polymer selected from the group consisting of homopolybutadiene-1,3 and a random copolymer of butadiene-1,3 and up to about 15% by weight total of said copolymer of copolymerized styrene and/or isoprene, said polymer exhibiting:

a. a glass transition temperature of from about -80.degree. to -100.degree. C. as determined by differential thermal analysis,
b. a crystalline melting point (peak values) in the unstretched state from about -10.degree. to +43.degree. C. as determined by differential thermal analysis,
c. a trans-1,4 content of from about 70 to 81% and a vinyl content of up to about 12% for the butadiene units,
d. a heterogeneity index of from about 4 to 40,
e. a number average molecular weight of from about 20,000 to 300,000,
f. crystallinity when stretched in the uncompounded and uncured state as shown by x-ray diffraction data,
g. green strength and building tack, and
h. a broad molecular weight distribution as determined by gel permeation chromotography.

5 more elements

Dependencies are inferred from the claim text.