Flame-retardant elastic block copolymer
The invention relates to a flameproofed resilient block polymer comprising polymerized units of at least one vinylaromatic monomer and at least one diene monomer with at least one flameproofing agent B) which comprises a compound comprising phosphorus, in particular a phosphorus-containing melamine compound, a process for the preparation and the use for the production of moldings.
1. A flameproofed resilient block polymer comprising polymerized units of at least one vinylaromatic monomer and at least one diene monomer with at least one flameproofing agent B, wherein the flameproofing agent B) comprises
B1) an expandable graphite,
B2) a compound comprising phosphorus, and
B3) a fluorine-containing polymer,
and wherein the phosphorus-containing compound B2 is a phosphorus compound with a melamine radical.
2. The block copolymer according to claim 1 , wherein the block copolymer comprises at least one block A having polymerized units of a vinylaromatic monomer and forming a hard phase and/or a block B having diene monomers and forming a first soft elastomeric phase and at least one elastomeric block B/A having polymerized units of both a vinylaromatic monomer and a diene and forming an optionally second or further soft phase.
3. The block copolymer according to claim 2 , wherein the glass transition temperature T g of block A is above 25° C. and that of block B/A is below 25° C. and the phase volume ratio of block A to block B/A is chosen so that the proportion of the hard phase, based on the total block copolymer, is 1-40% by volume and the proportion by weight of the diene is less than 50% by weight.
4. The block copolymer according to claim 1 , wherein the flameproofing agent is present in an amount of from 20 to 40% by weight, based on the block copolymer, including the flameproofing agent and other additives.
5. The block copolymer according to claim 1 , wherein the flameproofing agent B comprises:
from 20 to 80 parts by weight, based on the total flameproofing agent, of the expandable graphite B1 having an expansion temperature of >270° C.,
from 20 to 80 parts by weight, based on the total flameproofing agent, of the phosphorus-containing compound B2, and
from 0.1 to 5 parts by weight, based on the total flameproofing agent, of the fluorine-containing polymer B3.
6. The block copolymer according to claim 1 , wherein the phosphorus-containing compound B2 is a melamine-modified ammonium polyphosphate, a melamine polyphosphate or melamine phosphate.
7. The block copolymer according to claim 1 , wherein the phosphorus-containing compound B2 is a melamine polyphosphate.
8. A process for the preparation of a resilient block copolymer with a flameproofing agent according to claim 1 , which comprises mixing the block copolymer with the flameproofing agent in an extruder.
9. A process for the production of moldings which comprises utilizing the resilient block copolymer according to claim 1 .
10. A molding based on the resilient block copolymer according to claim 1 .
11. The molding according to claim 10 wherein the molding is a film or an extruded profile, tube, cable sheath, sealing material, base plate or a foam.