FIELD: chemistry.
SUBSTANCE: described is nitrile rubber which contains repeating units of at least one α,β-unsaturated nitrile and at least one conjugated diene and has chlorine content in the range of 4 to 25 ppm with respect to nitrile rubber. Described is a method of producing said nitrile rubber by emulsion polymerisation of at least one α,β-unsaturated nitrile, at least one conjugated diene and optionally one or more other copolymerisable monomers selected from a group comprising α,β-unsaturated mono- or dicarboxylic acids, esters and amides thereof, in the presence of a molecular weight regulator, with the latex which is obtained during polymerisation and contains nitrile rubber being subjected to coagulation and the coagulated nitrile rubber subsequently being washed, wherein (i) the latex obtained during emulsion polymerisation has a pH of at least 6 before the coagulation, (ii) coagulation of the latex is carried out using at least one salt of a mono-, di- or trivalent metal, which is optionally a chloride, as precipitant, (iii) coagulation of the latex is carried out in the presence of polyvinyl acetate, which is optionally partially or fully saponified, as coprecipitant, and (iv) coagulation of latex and/or treatment of the coagulated latex is carried out using water containing chloride ions under the condition that the salt of the mono-, di- or trivalent metal (ii) is not a chloride. A method of treating nitrile rubber obtained using the method described above is described, wherein nitrile rubber is subjected to (i) either a metathesis reaction only or (ii) a metathesis reaction and subsequent hydrogenation, or (iii) hydrogenation only, to obtain optionally hydrogenated nitrile rubber. Described is use of said nitrile rubber, optionally hydrogenated nitrile rubber, to obtain vulcanised mixtures, obtained by mixing at least one nitrile rubber or at least one optionally hydrogenated nitrile rubber, at least one cross-linking agent and optionally other additives. Described is a method of making moulded articles in form of a seal, a cap, a hose or a diaphragm, in particular an O-ring seal, a flat seal, a dynamic seal, a sealing sleeve, a sealing cap, an oil cooler hose, a hydraulic booster hose, an air conditioner hose, a thermal insulation hose, a diaphragm for hydro bearings or a diaphragm for a diaphragm pump, through vulcanisation during moulding, preferably via pressure casting of said vulcanised mixture.
EFFECT: nitrile rubber characterised by high stability during storage and high rate of vulcanisation are obtained, as well as with a preferable profile of properties, mainly with respect to contact of moulded articles based on such vulcanised rubber with metal structural components.
25 cl, 15 tbl, 5 dwg, 5 ex
