Branched and hydrogenated block copolymer, procedures for its preparation and use
AssigneeEnichem Elastomeri S.r.l.
InventorsSergio Custro, Gian T. Viola
Life of this patent
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Abstract
A branched and hydrogenated block copolymer can be defined by the formula [(EB).sub.1 --HT--A--(EB).sub.2 ].sub.n X, where (EB).sub.1 and (EB).sub.2 are hydrogenated polydiene blocks, A is a polyvinylaromatic block, HT is a random copolymer segment made up of hydrogenated dienic monomeric and vinylaromatic units, X is a coupling radical having a valence equal to n, and n is a whole number ranging from 3 to 20. This kind of block copolymer shows excellent mechanical characteristics and resistance to atmospheric agents, even when used in combination with other resins.
Claims12
Branched and hydrogenated block copolymer of the formula:
- [(EB).sub.1 --HT--A--(EB).sub.2 ].sub.n X
- where:
- (EB).sub.1 and (EB).sub.2 are hydrogenated polydiene blocks,
- A is a polyvinylaromatic block,
- HT is a random copolymer segment made up of hydrogenated dienic monomeric and vinylaromatic units,
- X is a coupling radical having a valence equal to n, and n is a whole number ranging from 3 to 20,
- the above copolymer having a weight average molecular weight of between 60,000 and 500,000;
- an A block content from 20 to 80% by weight;
- a (EB).sub.1 +(EB).sub.2 block content from 20 to 80% by weight;
- a weight ratio between blocks (EB).sub.1 and (EB).sub.2 from 0.1 to 1.0;
- and a HT segment content from 5 to 40% by weight.
Process for the preparation of a branched and hydrogenated block copolymer of the formula:
- [(EB).sub.1 --HT--A--(EB).sub.2 ].sub.n X
- where:
- (EB).sub.1 and (EB).sub.2 are hydrogenated polydiene blocks,
- A is a polyvinylaromatic block,
- HT is a random copolymer segment made up of hydrogenated dienic monomeric and vinylaromatic units,
- X is a coupling radical having a valence equal to n, and
- n is a whole number ranging from 3 to 20,
- the above copolymer having a weight average molecular weight of between 60,000 and 500,000;
- an A block content from 20 to 80% by weight;
- a (EB).sub.1 +(EB).sub.2 block content from 20 to 80% by weight;
- a weight ratio between blocks (EB).sub.1 and (EB).sub.2 from 0.1 to 1.0;
- and a HT segment content from 5 to 40% by weight,
- comprising the steps of:
- (a) polymerizing a mixture of diolefin and vinyl aromatic monomers until complete, or almost complete, conversion of the monomers to obtain a living copolymer of the formula B.sub.1 --T--A, where T is a random copolymer segment of dienic and vinylaromatic units, B.sub.1 is a polydiene block and A is as above defined,
- (b) adding a diene monomer to the copolymer obtained in step (a) and polymerizing the added diene monomer until complete, or almost complete conversion of said added diene monomer to obtain a living copolymer of the formula B.sub.1 --T--A--B.sub.2, where B.sub.1, T and A are as above defined and B.sub.2 is a polydiene block,
- (c) coupling the living polymeric chains obtained in step (b) with polyfunctional coupling agent to obtain a branched block copolymer of the formula (B.sub.1 --T--A--B.sub.2).sub.n X, where B.sub.1, T, A, B.sub.2, X and n are as above defined, and
- (d) hydrogenating the diene units of the copolymer obtained in step (c) by catalytic hydrogenation and
- (e) recovering said branched and hydrogenated block copolymer of the formula [(EB).sub.1 --HT--A--(EB).sub.2 ].sub.n X from the hydrogenation product of step (d), wherein EB.sub.1, HT, A, EB.sub.2, X and n are as above defined.
Dependencies are inferred from the claim text.