Branched block, copolymer, procedures for its preparation and use
AssigneeEnichem Elastomeri S.r.l.
InventorsSergio Custro, Alessandro Zazzetta
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Abstract
A branched block copolymer is described, which can be defined by the formula (B.sub.1 --T--A--B.sub.2).sub.n X, where B.sub.1 and B.sub.2 are polydiene blocks, A is an aromatic polyvinyl block, T is a random copolymer segment made up of dienic monomeric and aromatic vinyl 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 is used in formulations of adhesives having an excellent balance of adhesive, cohesive, rheological characteristics, as well as resistance to heat oxidation, and in compositions together with thermoplastic polymers capable of giving products with improved shock resistance and transparency.
Claims10
An impact resistant composition comprising:
- a thermoplastic resin and a branched block copolymer of the formula:
- (B.sub.1 -T-A-B.sub.2).sub.n X (I)
- where:
- B.sub.1 and B.sub.2 are polydienic blocks;
- A is a polyvinylaromatic block;
- T is a random copolymeric segment formed by dienic and vinylaromatic monomeric units;
- X is a coupling radical of valence n, and
- n is a whole number between 3 and 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 B.sub.1 +B.sub.2 block content from 20 to 80% by weight;
- a weight ratio between blocks B.sub.1 and B.sub.2 from 0.1 to 1.0;
- and a T segment content from 4 to 40% by weight.
Dependencies are inferred from the claim text.