Thermoplastic molding compositions

Thermoplastic molding compositions containing PA0 a. from 1 to 99 parts by weight of a thermoplastic copolymer of PA1 from 40 to 70 parts by weight methyl methacrylate, from 20 to 50 parts by weight .alpha.-methyl styrene and from 5 to 15 parts by weight acrylonitrile, PA0 b. from 1 to 99 parts by weight of a statistical, thermoplastic copolymer of PA1 from 70 to 95 parts by weight styrene and from 5 to 30 parts by weight maleic acid anhydride.

This invention relates to thermoplastic molding compositions containing: 
a. from 1 to 99 parts by weight, preferably from 5 to 95 parts by weight 
and more preferably from 10 to 90 parts by weight of a thermoplastic 
copolymer of from 40 to 70 parts by weight and preferably from 50 to 60 
parts by weight and more preferably 55.5 parts by weight methyl 
methacrylate, from 20 to 50 parts by weight, preferably from 30 to 40 
parts by weight and more preferably 34.5 parts by weight .alpha.-methyl 
styrene and from 5 to 15 parts by weight, preferably from 7 to 13 parts by 
weight and more preferably 10 parts by weight acrylonitrile, 
b. from 1 to 99 parts by weight, preferably from 5 to 95 parts by weight 
and more preferably from 10 to 90 parts by weight of a statistical, 
thermoplastic copolymer of from 70 to 95 parts by weight and preferably 
from 78 to 90 parts by weight styrene and from 5 to 30 parts by weight and 
preferably from 10 to 22 parts by weight maleic acid anhydride. 
The molding compositions according to the invention of a. and b. are 
"compatible" mixtures, as reflected in the occurrence of only one loss 
modulus maximum in the thermoplast and only one glass transition point the 
position of which is dependent on the particular compositions of the 
mixtures of a. and b. 
The heat deflection temperature under load of the molding compositions 
according to the invention extends from that of component a. to that of 
component b. and may be adjusted as required through the choice of the 
mixing ratio. 
By far the majority of plastics are incompatible with one another. It was 
therefore surprising to find that mixtures of components a. and b. 
according to the invention are completely miscible in the composition 
range according to the invention. 
Mixtures of styrene/maleic acid anhydride copolymers with certain other 
vinyl copolymers are known. 
DE-OS 1 950 599 describes transparent mixtures of high deflection 
temperature under load consisting of styrene c or (.alpha.-methyl 
styrene)/maleic acid anhydride and styrene or (.alpha.-methyl 
styrene)/acrylonitrile or (methacrylonitrile) copolymers. 
DE-OS 2 024 944 describes transparent molding compositions of high 
deflection temperature under load consisting of styrene/maleic acid 
anhydride copolymers and methyl methacrylate/styrene/alkyl acrylate 
copolymers. 
DE-OS 2 229 129 describes transparent, glass fiber-reinforced molding 
compositions of styrene/maleic acid anhydride copolymers and methyl 
methacrylate/styrene copolymers. 
DE-OS 3 332 279 describes transparent thermoplastic molding compositions of 
high deflection temperature under load consisting of styrene/maleic acid 
anhydride copolymers and styrene/acrylonitrile copolymers, the ratio by 
weight of acrylonitrile to maleic acid anhydride being lower than 1.45 and 
greater than 0.7. 
U.S. Pat. No. 4 451 617 and U.S. Pat. No. 4 408 010 describe molding 
compositions of high deflection temperature under load consisting of 
styrene/maleic acid anhydride copolymers and styrene/maleic imide 
copolymers. 
Copolymers according to component a. are known and may be prepared by 
radical copolymerization, more especially by emulsion, suspension, 
solution or mass polymerization. Copolymers according to component a. 
generally have molecular weights M.sub.w of from 15 kg/mole to 200 
kg/mole. 
Copolymers according to component b. are also known. They have a 
statistical structure and are preferably prepared by mass or solution 
polymerization with incomplete reaction from the corresponding monomers. 
Copolymers according to component b. generally have molecular weights 
M.sub.w of from 50 kg/mole to 300 kg/mole. 
The molding compositions according to the invention of components a. and b. 
may contain the usual additives, such as stabilizers, pigments, flow aids, 
flameproofing agents, mold release agents and/or antistatic agents, in the 
usual quantities. 
The molding compositions according to the invention of components a. and b. 
and, optionally, other known additives may be prepared by mixing the 
constituents in known manner and then melt-compounding or melt-extruding 
the resulting mixture at temperatures of from 200 to 300.degree. C. in 
standard machines, such as internal kneaders, extruders or twin-screw 
extruders. Components a. and b. may also be dissolved in a suitable 
organic solvent and then concentrated by evaporation in suitable 
apparatus. 
Accordingly, the present invention also relates to this process for the 
production of thermoplastic molding compositions of components a. and b. 
and optionally known additives. 
The molding compositions according to the invention may be used for the 
production of moldings of all kinds, more especially by injection molding. 
Examples of moldings which may be produced from the molding compositions 
according to the invention include machine housings, parts for the 
automotive field and building field and components for electrical 
equipment. 
Moldings may also be produced by deep drawing from sheets and films.