Basf Aktiengesellschaft

Hans Mittnacht

Adolf Echte

Hermann Gausepohl

Helmut Jenne

Klaus Bronstert

Gerhard Heinz

Peter Klaerner

Karl Gerberding

Rainer Bueschl

Rudolf H Jung

Hans-Dieter Schwaben

Burghard Schmitt

Rainer Schlichtmann

Hubert Kindler

Ingo H Dorn

Manfred Lieb

Jurgen Pohrt

Hansjoerg Adler

Paul Witimer

Hermann P Hofmann

Konrad Schulte

An impact-resistant thermoplastic molding material which contains, based in each case on A+B, from 80 to 50% by weight of a hard matrix A of polystyrene having a molecular weight M.eta. of from 150,000 to 200,000 and from 50 to 20% by weight of a soft phase B which is uniformly distributed in the hard matrix and has a median particle diameter d.sub.50 (volume average) of from 1 to 10 .mu.m, and can be obtained by polymerizing styrene in the presence of an elastomeric grafting base, advantageously has a molecular weight of the grafted branches of from 1.1 to 1.35 times the molecular weight of the hard matrix, and the degree of grafting is from 50 to 100%.

Impact-resistant thermoplastic molding material and its use

An impact resistance thermoplastic molding composition contains, each percentage being based on A+B, from 80 to 55% by weight of a hard matrix A of a copolymer containing at least 95% by weight of an aromatic vinyl monomer a.sub.11 of from 8 to 10 carbon atoms and at least one comonomer a.sub.12 in a proportion of 0.1 to 5% by weight, based on A, and from 45 to 20% by weight of a soft phase B which, uniformly dispersed in the hard matrix, has an average particle diameter d.sub.50 (volume average) of from 3.5 to 9 .mu.m and is obtainable by polymerization of the mixture of monomers a.sub.11 and a.sub.12 in the presence of an elastomer (rubber) and subsequent isolation of the useful product, wherein the comonomer a.sub.12 has the general formula I ##STR1## where X is --OR.sup.2, --COOR.sup.2 or --CONHR.sup.3,

Impact resistant thermoplastic molding composition and use thereof

A process, carried out without a diluent or in solution, in more than 2 reaction zones, for the continuous preparation of rubber-modified polymers of vinylaromatics, wherein a monomeric aromatic vinyl compound and an elastomeric polymer, in an amount of from 3 to 16% by weight based on the monomer, are polymerized, in the absence of a free radical initiator, but in the presence of a mercaptan as a chain transfer agent, at from 80.degree. to 180.degree. C. in a first reaction zone, with stirring, up to a maximum monomer conversion, U.sub.max, given by the equation

Process for the continuous preparation of rubber-modified polymers of

A process for the preparation of branched block copolymers of from 60 to 95% by weight of a monovinyl-aromatic monomer and from 40 to 5% by weight of a conjugated diene by polymerizing the monomers in an inert solvent in the presence of a monolithium-hydrocarbon as the initiator, wherein, in a first process stage (a), from 50 to 80, or where necessary at most 90, % by weight of the total amount of monovinyl-aromatic compound are polymerized to virtually complete conversion in the presence of a relatively small amount of the monolithium-hydrocarbon. This stage is carried out by starting with from 30 to 70% by weight of the vinyl-aromatic monomer and adding from 70 to 30% by weight in the feed, during the polymerization, in such a way that the polymerization temperature, which at the start of the polymerization is from 30.degree. to 40.degree. C., is kept at from 45.degree. to 70.degree. C., with use of reflux cooling. After all the monomer feed has been added, the reaction temperature is lowered to 30.degree.-40.degree. C. by evaporative cooling. In a second process stage (b), an additional amount of initiator is added to the reaction solution, after which from 1 to 30% by weight of the total amount of monovinyl-aromatic monomer can be added, the sum of the amounts of monovinyl-aromatic monomer added in the first and second process stages being at most 90% by weight of the total amount of monovinyl-aromatic monomer. The monovinyl-aromatic monomer added in the second process stage is polymerized to virtually complete conversion, employing the temperature profile described for stage (a). In process stage (c), the remainder of the monovinyl-aromatic monomer and all of the conjugated diene are added, at least predominantly in the form of a mixture, and polymerized so that the reaction temperature does not rise above 90.degree.-110.degree. C. Finally, after virtually complete conversion of the monomers, and preferably without prior cooling, a suitable liquid polyfunctional coupling agent is run in undiluted and the mixture of the linear block copolymers obtained, which still contain active terminal lithium-carbon bonds, is coupled, with stirring, to form branched block copolymers. The products prepared according to the invention are used for injection molding.

Preparation of branched block copolymers

Thermoplastic molding materials which contain a copolymer which has been made impact-resistant with a rubber. The copolymer is produced by polymerizing a mixture of a monovinyl-aromatic compound and an acrylic acid derivative or methacrylic acid derivative in the presence of a rubber. The folding materials contain a specific proportion of soft component. The diameter of the particles of the soft component, and the swelling index of the soft component, lie within a specific range, and the tensile strength of the molding material is higher than the yield strength.

Impact-resistant thermoplastic molding materials with improved

Thermoplastic molding compositions, based on polymers of a monovinyl-aromatic compound which have been modified with rubber to increase their impact strength, which also exhibit increased stress crack resistance. The increased stress crack resistance is achieved if the proportion of the soft component in the polymer which has been modified to increase its impact strength, and the particle size and swelling index of the soft component phase, conform to particular values, and the tensile strength and yield stress of the thermoplastic molding compositions bear a particular ratio to one another. The molding compositions may in particular be used for the manufacture of internal liners of refrigerators and foodstuff packaging containers.

Impact-resistant thermoplastic molding compositions with increased

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