摘要:
Storage-stable polychloroprene is obtained, using a polymerization initiator comprising a mixture of(1) a redox system comprising(a) a reducing agent selected from the group consisting of(i) sodium dithionite,(ii) formamidine sulphinic acid, and(iii) a mixture from (i) and (ii),(b) potassium peroxodisulphate as an oxidizing agent and, optionally,(2) sodium anthraquinone-.beta.-sulphonate as a co-activatorin the presence of oxygen, wherein from 10 to 90 by weight of the initiator are present at the commencement of polymerization and the remainder is added during the polymerization, and after a certain degree of conversion the reducing agent is the only component of redox system (1) which remains to be added.
摘要:
An improved process of polymerizing an aqueous emulsion of chloroprene monomer stabilized with phenothiazine wherein polymerization is initiated in the presence of phenothiazine stabilizer and molecular oxygen with a polymerization initiator comprising sodium dithionite.
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:
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:
The present invention relates to a process for reducing mold contamination in an injection molding process by using a mixture of nitrile rubbers, in the range of from 0.1-0.5 wt. % of fatty acids and optionally further additives.
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:
Vulcanizates of polychloroprene materials containing fluorinated polyolefin have a decreased rebound elasticity without having a significantly adverse effect on the mechanical properties.
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.
摘要:
A rubber composition which contains a rubber mixture that can be vulcanized with a vulcanizing agent, which includes at least one rubber component, at least one filler having nucleophilic groups, gel particles comprising a rubber, having a particle size between about 3×10−9 and about 1×10−6 m and a swelling index in toluene of about 1 to about 15 and whose surface has electrophilic centers, and a substance acting as a coupling agent between the filler having nucleophilic groups and the additional filler, the substance acting as a coupling agent having the following structure: X—R1—Si—(R2)3, wherein X is a nucleophilic group, R1 is an alkyl group having up to about 6 carbon atoms or a phenyl group, and R2 may be the same as or different from each other and from R1 and is an alkyl or alkoxy group having up to 6 carbon atoms and at least one of R2 is an alkoxy group. The rubber composition has improved hysteresis behavior in the vulcanized state so that with the use of this rubber composition in tires, the rolling resistance is reduced and the wet slippage behavior is improved in relation to conventional rubber compositions. A method of adding and blending the rubber composition as well as a composition useful for tire treads and vehicle tires containing the composition are disclosed.
摘要:
A rubber composition, which contains a rubber mixture that can be vulcanized with a vulcanizing agent, which includes at least one rubber component, at least one filler, gel particles comprising a rubber, having a particle size between about 3.times.10.sup.-9 and about 1.times.10.sup.-6 m and a swelling index in toluene of about 1 to about 15 and whose surface has electrophilic centers, and a substance which acts as a coupling agent between the gel particles and which has the structure A--R--A, wherein A is a nucleophilic group, and R is a saturated or unsaturated hydrocarbon group. The rubber composition has improved hysteresis behavior in the vulcanized state so that when this rubber composition is used in tires, the rolling resistance is reduced and the wet slippage behavior is improved in relation to the conventional rubber compositions. A method of formulating the rubber composition as well as a composition useful for tire treads and vehicle tires containing the composition are disclosed.