Bayer Aktiengesellschaft

Eberhard Muller

Rudiger Musch

Werner Obrecht

Peter Wendling

Wilhelm Gobel

Wolfgang Konter

Gerhard Hohmann

Hans Magg

Rudolf Casper

Gunter Marwede

Ludwig Mott

Michael Happ

Karl-Heinz Schabel

Vulcanizable, mercaptan- and/or xanthogen-disulfide-regulated polychloroprene rubber are produced by emulsion polymerization of chloroprene and, based on polymerizable monomer used, 0 to 30 parts by weight ethylenically unsaturated, other monomers copolymerizable with chloroprene in an alkaline medium by a process in which

Process for the production of vulcanizable mercaptan-and/or xanthogen

This invention relates to mixtures of polychloroprene elastomers which are distinguished by their good processibility and excellent cold resistance.

Mixtures of chloroprene polymers

The polymerization of chloroprene leads to non-colored products when a mixture of 2.0 to 5.0% by weight of a salt of disproportionated abietic acid and 0.1 to 1.0% by weight, in each case relative to the total amount of monomer, of a compound of the formula ##STR1## in which R.sub.1 and R.sub.2, independently of one another, denote hydrogen or CH.sub.3,

Process for polymerization of chloroprene

The combination of unmodified resinic acids and direct peptization in the production of sulfur-modified polychloroprene leads to a favorable ratio of elasticity to viscosity.

Process for the production of sulfur-modified polychloroprene

Toluene-soluble, sulphur-modified polychloroprene is obtained by emulsion copolymerization of chloroprene, sulphur and optionally further monomers which are copolymerizable with chloroprene and sulphur using a peroxy activator and subsequent working-up by stabilizing, stopping, degassing and isolating without separate peptization, in that polymerization is carried out in the presence of dithiocarbamates and/or xanthogenates and the activator is metered in continuously or batch-wise during the course of polymerization.

Process for the production of toluene-soluble, sulphur-modified

The invention relates to a polychloroprene rubber which shows advantages over the prior art in the sum total of its performance properties, namely vulcanization rate, tensile strength, elongation at break, modulus, tear propagation resistance and thermal stability of the vulcanizate.

Polychloroprene mixtures

Storage-stable polychloroprene is obtained, by aqueous emulsion polymerization, using xanthogen disulphides as molecular weight regulators, when a peptizing agent is added after the end of the polymerization.

Process for the preparation of polychloroprene

An improved process for the preparation of polychloroprene by the emulsion (co)polymerization of chloroprene and optionally other monomers capable of copolymerization with chloroprene, using a peroxo activator, and subsequent working up of the product by stopping the reaction, stabilizing, degassing and isolating the product, characterized in that polymerization is carried out in the presence of dithiocarbamates and/or xanthates and 0 to 0.5% by weight of sodium .beta.-anthraquinone sulphonate.

Polymerization of chloroprene with xanthates and dithiocarbamates

Gel-free polychloroprene is obtained, at high monomer conversions, using a polymerization initiator comprising sodium dithionite or a mixture of sodium dithionite with formamidinesulphinic acid or with potassium peroxydisulphate or with formamidinesulphinic acid and potassium peroxodisulphate or with potassium peroxodisulphate and sodium anthraquinon-.beta.-sulphonate or with formamidinesulphinic acid and potassium peroxodisulphate and sodium anthraquinone-.beta.-sulphonate, and in the presence of oxygen and a chain transfer agent when 30 to 90% of the initiator is present at the commencement of polymerization and the remainder is added in portions during the polymerization, only further sodium dithionite being added at a conversion &gt;60% in the case of an initiator combination, and when 20 to 80% by weight of the total amount of chain transfer agents is present before or at the commencement of polymerization and the remaining amount is added in one or more parts at monomer conversions of greater than 20%.

Polymerization of chloroprene

An elastomeric mass of polychloroprene sol and polychloroprene gel in proportions in the range of 95:5 to 25:75% by weight in which the polychloroprene sol is free from sulphur and the polychloroprene gel used is a sulphur-containing gel with xanthate or carbamate functions has better processing characteristics than the pure sol component without the expected deterioration in the mechanical properties of the vulcanisates prepared from the mass.

Elastomeric mass of polychloroprene sol and polychloroprene gel

Solid polychloroprene mixtures consisting of sol and gel polymer, wherein the sol component consists of a copolymer of chloroprene and from 0.75 to 0.32% by weight of sulphur, based on the total quantity of unsaturated compounds of the sol polychloroprene, and the gel component consists of a copolymer of chloroprene, from 0.4 to 1.0% by weight of sulphur, based on the total quantity of unsaturated compounds of the gel polychloroprene and from 7.5.times.10.sup.-3 to 3.0.times.10.sup.-2 mols, based on 100 g of the total quantity of monomer of the gel polychloroprene, of a compound corresponding to the general formula ##STR1## wherein R.sub.1 and R.sub.2 each represents a hydrogen atom or C.sub.1 -C.sub.4 alkyl group, and X represents a C.sub.2 -C.sub.10 alkylene group, are suitable for the production by extrusion and by calandering of rubber articles which may be subjected to high strains.

Polychloroprene mixtures and the use thereof

Vulcanizable, elastomeric chloroprene/sulfur copolymers having viscosities of from 60 to 35 ME, strengths of greater than 20 MPa and sulfur contents of from about 0.3 to 0.45% by weight are obtained by polymerizing chloroprene in the presence of from 0.05 to 0.40% by weight of sulfur to form a latex I, polymerizing chloroprene in the presence of from 0.5 to 1.5% by weight of sulfur to form a latex II, mixing latices I and II, optionally together with other sulfur-modified polychloroprene latices, in a ratio of from 4:1 to 1:4 (based in each case on solids) and peptizing the mixture, followed by working up to form the solid rubber, the percentages quoted being based on the quantity of monomer.

Production of sulfur-modified solid chloroprene rubbers

Vulcanisable, elastomeric chloroprene-sulphur copolymers having viscosities of from 60 to 35 MU, strengths of &gt;20 MPa and sulphur contents of from about 0.5 to 0.7%, by weight, in the batch are obtained by polymerising chloroprene in the presence of from 0.10 to 0.35%, by weight, of sulphur to form a latex I, polymerising chloroprene in the presence of from 0.50 to 1.00% by weight, of sulphur to form a latex II, mixing latices I and II in a ratio of from 4:1 to 1:4 (based in each case on solids), optionally together with other sulphur-modified polychloroprene latices, the mixture is peptised and worked-up to form the solid rubber, the percentages quoted being based on the quantity of monomer.

Process for the production of sulphur-modified solid chloroprene rubbers

Process for the homopolymerisation and copolymerisation of conjugated dienes in inert organic solvents on alkali metal amides as catalysts in the presence of a solvating agent for the amide.

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Dormagen, Germany

Eberhard Muller