Concentrated latex of synthetic rubbers and the method for the preparation thereof

A method of the preparation of a concentrated aqueous latex comprising:

• 1. at least one block copolymer selected from the group consisting of block copolymers having a molecular weight of from 10,000 to 500,000 and the general configuration:
• A-b-a;
• (a-b).sub.n ;
• B-(A-B).sub.n
• A-(b-a).sub.n and A-B-(B-A).sub.n
• wherein n is an integer of at least 2, A is a non-elastic polymer or copolymer containing styrene or .alpha.-methyl styrene and having a second order transition temperature of at least 25.degree. C, and B is an elastic polymer or copolymer containing 1,3-butadiene or isoprene having a second order transition temperature up to 10.degree. C, the A- content of said block copolymer being from 10% to 70% by weight based on the total weight of said copolymer;
• 2. an emulsifying agent which is a mixture of:
• a. from 0.5 to 15 parts by weight per 100 parts by weight of polymer of a higher fatty acid or a salt thereof, rosin acid or a salt thereof, or a disproportioned rosin acid or a salt thereof;
• and
• b. from 0.5 to 15 parts by weight per 100 parts by weight of polymer of a compound represented by the general formula ##STR9## wherein R.sub.1 is alkyl having 8-18 carbon or alkylphenyl in which the alkyl has 8-12 carbons, R.sub.2 is alkylene having 2-5 carbons and m is an integer from 3 to 50;
• which method comprises dissolving the emulsifying agent in an aqueous solution of the block copolymer and emulsifying by the addition of an aqueous alkali solution.