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 also contains magnesium ions in concentration of 100-180 ppm and calcium ions in concentration of 50-145 ppm, respectively, with respect to nitrile rubber. Described is a method of producing said nitrile rubber via 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 at least one 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 magnesium salt, up to 40 wt % of which is optionally replaced with a calcium salt, as precipitant, (iii) the coprecipitant used during coagulation of latex is gelatine, (iv) temperature of latex before reacting with the coprecipitant (iii) is kept higher than 50°C, and then raised to 100°C, and (v) coagulation of latex and/or treatment of the coagulated latex is carried out using water containing calcium ions, under the condition that coagulation is carried out without a calcium salt as a precipitant. Treatment of 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, such as 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, a cap for protection from dust, a plug seal, a thermal insulation hose (with or without a PVC additive), an oil cooler hose, an air hose, a servo control hose or a pump diaphragm, through vulcanisation during moulding, via pressure casting of said vulcanised mixture.
EFFECT: special nitrile rubber, characterised by high stability during storage and high rate of vulcanisation is obtained.
25 cl, 15 tbl, 38 ex
