Brominated flame retardant

A brominated vinylaromatic-diene block copolymer (Br-SBC) comprising at least one vinylaromatic polymer block S and at least one brominated diene polymer block BB,

• wherein
• before bromination the weight-average molar mass Mw of the block S is greater than or equal to Mw of the block BB;
• the molar mass Mw of the block BB (before bromination) is from 50000 to 130 000 g/mol;
• and
• the molar mass Mw of the block S is from 60000 to 300000 g/mol;
• wherein the molar mass Mw is determined by means of GPC in accordance with ISO 16014-3:2012 (relative to polystyrene standards at 25° C. in THF) before bromination and
• wherein the block copolymer has a linear structure of the formula K-S-BB-A (Ia), in which K is absent or K and A, respectively mutually independently, are a vinylaromatic (co)polymer block different from S and BB;
• and the molar mass Mw of the blocks K and A is respectively smaller than the molar mass Mw of the block BB;
• or
• the block copolymer has a star-shaped structure of the formula
• Z—[(P)p(Q)q(R)r]m (Ib),
• in which
• Z is a moeiety of a polyfunctional coupling agent or initiator;
• P, Q, R . . . are various star branches, where
• star branch P has the structure ˜BB-S or ˜A-BB-S;
• and the star branches Q and R mutually independently have the structure ˜A-BB, ˜S, ˜BB, and/or ˜BB-A;
• in which ˜ is the location of bonding to the moiety Z, and A is a vinylaromatic (co)polymer block which differs from S and BB and has a molar mass Mw smaller than Mw of the block BB;
• p is 1 or 2,
• q and r are independently natural numbers greater than 0;
• and
• m is the total number of star branches or the sum of the indices p, q, r . . . , where m is a natural number from 3 to 10;
• wherein the molar mass Mw of the blocks K and A—mutually independently—is in the range from 15000 to 35000 g/mol.