Thermoplastic polyester moulding compositions which have good impact strength

• US 4,535,124 A
• Filed: 06/26/1984
• Issued: 08/13/1985
• Est. Priority Date: 07/06/1983
• Status: Expired due to Fees

• Current Assignee: Bayer AG
• Original Assignee: Bayer AG
• Inventors: Lindner, Christian, Morbitzer, Leo, Binsack, Rudolf, Rempel, Dieter
• Primary Examiner(s): Michl, Paul R.
• Application Number:
  US06/624,576
• Time in Patent Office: 413 Days
• Field of Search: 525/64, 525/67
• US Class Current: 525/67
• CPC Class Codes: C08L 51/00 Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds for ABS polymers C08L55/02; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 67/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds C08L67/06 takes precedence

Abstract

The present invention relates to thermoplastic moulding compositions, which have improved impact strength at low temperature, comprising thermoplastic polyesters, in particular polyalkylene terephthalates, and grafted, partially or highly cross-linked diene rubbers and/or acrylate rubbers having a bimodal rubber particle size distribution.

Claims

1. Thermoplastic moulding compositions comprising

(A) from 65 to 97% by weight (based on A+B) of thermoplastic polyester and

(B) from 3 to 35% by weight (based on A+B) of the graft product

of at least one vinyl monomer selected from styrene, acrylonitrile and methyl methacrylate on particle-shaped, at least partially cross-linked diene rubbers and/or alkyl acrylate rubbers having an average rubber particle diameter of from 0.05 to 1 μ

m, the graft products having a rubber content of from 60 to 85%, by weight, characterised in that the graft products B are produced on the basis of a mixture of

a. from 20 to 80% by weight (based on a+b) of a rubber latex having a particle diameter d₅₀ of from 0.05 to 0.19 μ

m, and

b. from 80 to 20% by weight (based on a+b) of a rubber latex having a particle diameter d₅₀ of from 0.2 to 1.0 μ

m

with the limitation that

(1) d₅₀ (b) is larger than d₅₀ (a) by a factor of from 1.5 to 8,

(2) the quotient Q=(d₉₀ -d₁₀)/d₅₀ of the particular rubbers is at most 2, and

(3) the difference d₁₀ (b)-d₉₀ (a) is from 0.01 to -0.10.

2. Thermoplastic moulding compositions according to claim 1, characterised in that the graft product B is produced by mixing a rubber latex corresponding to (a) and a rubber latex corresponding to (b) and subsequently graft polymerising the vinyl monomers.

3. Thermoplastic moulding compositions according to claim 1, characterised in that the graft product B is produced by graft polymerising the vinyl monomers on a rubber latex corresponding to (a) and separately graft polymerising the vinyl monomers on a rubber latex corresponding to (b) and subsequently mixing the graft products which are obtained in this way.

4. Thermoplastic moulding compositions according to claim 1, characterised in that the diene rubbers or the alkyl acrylate rubbers have a gel content of ≧

80% by weight.

5. Thermoplastic moulding compositions according to claim 1, characterised in that the alkyl acrylate-rubbers are cross-linked with triallylcyanurate and/or triallylisocyanurate.

6. Thermoplastic moulding compositions according to claim 1, characterised in that the alkyl acrylate-rubbers contain a polybutadiene core.

7. Thermoplastic moulding compositions according to claim 1, characterised in that they contain free copolymer resin of graft monomers in a quantity of ≦

15% by weight and have a Staudinger index [η

]≦

0.6 dl/g, measured in DMF at 25°

C.

8. Thermoplastic moulding compositions according to claim 1, characterised in that up to 80% by weight of the thermoplastic polyesters A are aromatic polycarbonates.

9. Thermoplastic moulding compositions according to claim 1, characterised in that they contain ≦

60% by weight of glass fibres.