Flame-resistant polycarbonate-polyester blend
The present invention relates to a molding compound containing A) 45 to 65 wt. % of at least one aromatic polycarbonate, polyester carbonate or mixtures thereof, B) 18 to 31 wt. % of at least one polybutylene terephthalate having rheological properties of 5 g/10 min to 30 g/10 min determined according to DIN EN ISO 1133 at 250° C. measuring temperature and a load of 2.16 kg, C) 3 to 10 wt % of at least one rubber-modified graft polymer with a graft base consisting of a silicone-acrylate composite rubber and a silicone rubber content of 20 to 60 wt. % relative to the graft base, D) 8 to 13 wt. % of at least one phosphazene, and E) 0 to 8.0 wt. % of at least one polymer additive, the weight ratio of components D to C) being in the range of 1.3:1 to 2.5:1. The invention also relates to a method for producing the molding compound, to the use of the molding compound for producing moldings and to the moldings as such.
1 . A thermoplastic molding compound consisting of
A) 45% to 65% by weight of at least one of an aromatic polycarbonate, polyestercarbonate, and mixtures thereof,
B) 18% by weight to 31% by weight of at least one polybutylene terephthalate having a flowability of 5 g/10 min to 30 g/10 min to DIN EN ISO 1133 at measurement temperature 250° C. and a load of 2.16 kg, wherein the polybutylene terephthalate comprises structural units derived from terephthalic acid and butane-1,4-diol and from no other acid or diol
C) 3% to 10% by weight of at least one rubber-modified graft polymer having a graft base comprising a silicone-acrylate composite rubber and a silicone rubber content of 20% to 60% by weight based on the graft base,
D) 8% to 13% by weight of at least one phosphazene,
E) 0% to 8.0% by weight of at least one polymer additive selected from the group consisting of lubricants and demolding agents, antistats, conductivity additives, stabilizers, anti-drip agents, flame retardant synergists, smoke inhibitors, dyes and pigments,
wherein the weight ratio of components D) to C) is from 1.3:1 to 2.5:1.
2 . The molding compound as claimed in claim 1 , characterized in that component C is a graft polymer comprising
C.1 8% to 20% by weight, based on component C, of at least one vinyl monomer onto
C.2 92% to 80% by weight based on component C of a graft base composed of silicone-acrylate composite rubber.
3 . The molding compound as claimed in claim 2 , characterized in that C.1 is methyl methacrylate.
4 . The molding compound as claimed in claim 1 , characterized in that the graft base of component C includes a silicone rubber content of 25% to 50% by weight, based on the graft base.
5 . The molding compound as claimed in claim 1 , characterized in that the weight ratio of component D to component C is 2:1 to 2.5:1.
6 . The molding compound as claimed in claim 1 , wherein
Component A is a linear aromatic polycarbonate based on bisphenol A,
Component B is a polybutylene terephthalate comprising structural units derived from terephthalic acid and butane-1,4-diol and from no other acid or diol,
Component D is a cyclic phenoxyphosphazene of formula (V)
where k is an integer from 1 to 10.
7 . The molding compound as claimed in claim 1 , exhibiting a flame retardancy rating of UL 94 V-0 at 2.4 mm thickness in combination with Izod notched impact resistance of at least 35 kJ/m2 at room temperature.
8 . The molding compound as claimed in claim 1 , wherein
Component A is a linear aromatic polycarbonate based on bisphenol A,
Component D is a cyclic phenoxyphosphazene of formula (V)
where k is an integer from 1 to 10,
Component E is selected from the group consisting of lubricants and demolding agents, stabilizers, anti-drip agents, dyes and pigments.
9 . A molded article comprising a molding compound as claimed in claim 1 .