摘要:
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,m denotes a number from 0 to 14,n denotes a number from 0 to 13,p denotes a number from 0 to 2, andy denotes hydrogen, Na or K, andthe total number of aliphatic carbon atoms is 11 to 15,is used as emulsifier, the emulsifiers having the advantage of being biologically degradable.
摘要:
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.
摘要:
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 >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%.
摘要:
Disclosed is a self-contained radiant unit in the form of a portal for use particularly as a drying and baking tunnel for the automobile industry which is equipped with a plurality of infrared lamps on its inner surfaces. Air inlet openings are provided in the roof and/or side walls of the portal, at least over the region midway along with their horizontal extension, for the turbulence-free removal of the vapors emanating from the surface of the object being treated as well as of suspended particles present in the drying and baking zone.
摘要:
This invention relates to mixtures of polychloroprene elastomers which are distinguished by their good processibility and excellent cold resistance.
摘要:
Proposed is a method for the erection of structures, such as bridges, that display pre-fabricated concrete beams, according to which the individual pre-fabricated beams are produced, on the spot, on a feed rigging within the corresponding work area of the structure, in a heated and laterally tiltable form. After removal from the form, the thusly produced pre-fabricated beams are transferred sidewardly into their final position by means of gantry cranes. During concretizing of the individual pre-fabricated beams, flexure of the feed rigging carrying the form is equalized in continuous fashion, in correspondence with the progressing, concretizing process, by transfer pumping of ballast liquid. Correspondingly with progression of construction, the feed rigging displaying a freely suspended cantilever is transferred in progressive fashion onto support girders of the structure that have been prepared beforehand, just like the gantry cranes, which can be pretransported from the support girders supporting it to the next support girders. Also capable of being equalized are different inclinations of the support girders, such as curvatures in the ground plane of the structure, for example the access to bridges.
摘要:
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.
摘要:
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.
摘要:
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(1) 0.1 to 10 parts by weight of a tricyclic diterpene carboxylic acid containing at least two conjugated C.dbd.C double bonds per molecule, based on the polymerizable monomer used, and optionally(2) 0.1 to 5 parts by weight, based on polymerizable monomer used, fatty acid estersare used for their production.The polychloroprene produced in accordance with the invention may be used for the production of vulcanized rubber articles. The polychloroprene rubbers produced by the process according to the invention have a minimal tendency to foul metal molds. The pollution of wastewaters by the process according to the invention is minimal. The well-known favorable properties of polychloroprene remain unaffected.
摘要:
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.