Polycarbonate molding compositions with improved melt flow and chemical resistance

1. A thermoplastic molding composition consisting essentially of

A) at least one member selected from the group consisting of aromatic polycarbonate and polyester carbonate,

B) a graft polymer of at least one vinyl monomer on at least one rubber having a glass transition temperature of <10° C. as graft base,

C) vinyl (co)polymer having weight-average molecular weight of 1500 to 5000 g/mol and glass transition temperature of >40° C. consisting essentially of (1) α-methyl styrene and (2) at least one member selected from a first group consisting of butyl acrylate and glycidyl methacrylate, and (3) at least one member selected from a second group consisting of styrene, acrylonitrile and maleic anhydride,

D) at least one phosphorus-based flame retardant flame retardant conforming structurally to formula (IV)

wherein

R 1 , R 2 , R 3 and R 4 mutually independently denote C 1 to C 8 alkyl, C 5 to C 6 cycloalkyl, C 6 to C 20 aryl or C 7 to C 12 aralkyl,

n mutually independently denotes 0 or 1

q denotes 0 to 30 and

X denotes a mononuclear or polynuclear aromatic radical having 6 to 30 C atoms, or a linear or branched aliphatic radical having 2 to 30 C atoms, which may be OH-substituted and may contain up to 8 ether bonds,

and

E) an anti-dripping agent.

2. The composition according to claim 1 wherein the weight-average molecular weight M w of component C is 2000 to 4500 g/mol and its glass transition temperature is >50° C.

3. The composition according to claim 1 , wherein X stands for a member selected from the group consisting of

or chlorinated or brominated derivatives thereof

R 1 stands for phenyl or C 1 -C 4 alkyl-substituted phenyl and

q denotes 0.5 to 6.

4. The composition according to claim 1 , further containing at least one additive selected from the group consisting of lubricant, release agent, nucleating agent, antistatic agent, stabilizer, filler, reinforcing agent, flame retardant synergist, dye and pigment.

5. The composition according to claim 1 wherein the anti-dripping agent is fluorinated polyolefin in the form of a pre-compound or a masterbatch with a component B) or a vinyl (co)polymer.

6. The composition according to claim 5 , wherein the anti-dripping agent is fluorinated polyolefin in the form of a pre-compound or masterbatch with styrene/acrylonitrile copolymer or polymethyl methacrylate.

7. A molded article comprising the composition of claim 1 .

8. The composition of claim 1 , wherein said A is present in an amount of 20 to 98 parts by weight, said B is present in an amount of 1 to 80 parts by weight and said C is present in an amount of 0.1 to 20 parts by weight.

9. The composition according to claim 1 , wherein component B) comprise at least one graft polymers of 5 to 95% relative to the weight of the graft polymer of the polymerized product of a mixture comprising

(i) 50 to 99% relative to the weight of the mixture of at least one monomer selected from a third group consisting of vinyl aromatic, ring-substituted vinyl aromatic and methacrylic acid (C 1 -C 8 ) alkyl ester and

(ii) 1 to 50% relative to the weight of the mixture of at least one monomer selected from a fourth group consisting of vinyl cyanide, (meth)acrylic acid (C 1 -C 8 ) alkyl ester and derivative of unsaturated carboxylic acid on 95 to 5% relative to the weight of the graft polymer of a rubber having glass transition temperatures of <10° C. as graft base.

10. The composition according to claim 9 , wherein said third group consists of styrene, α-methyl styrene and methyl methacrylate and wherein fourth group consists of acrylonitrile, maleic anhydride and methyl methacrylate.

11. The composition according to claim 9 , wherein the mixture contains styrene and acrylonitrile.

12. The composition according to claim 9 , wherein the graft base is at least one member selected from the group consisting of diene rubber, acrylate rubber, EP(D)M rubber, polyurethane rubber, and silicone rubber.

13. The composition according to claim 12 , wherein the graft base is at least one member selected from the group consisting of diene rubber, acrylate rubber and silicone-acrylate rubber.