| 摘要 |
#CMT# #/CMT# Producing nitrile rubbers, comprises carrying out emulsion polymerization of at least one alpha ,beta -unsaturated nitrile, at least one conjugated diene and optionally at least one further copolymerizable monomer. The emulsion polymerization is carried out using a redox system, which comprises (a) at least one peroxo compound as an oxidizing agent, (b) at least a reducing agent and (c) iron(II)chloride. #CMT# : #/CMT# Independent claims are also included for: (1) the nitrile rubber comprising repeating units, obtained by the above mentioned method or obtained from the nitrile rubber by subjecting to a metathesis reaction; (2) a hydrogenated nitrile rubber obtained from the nitrile rubber, by subjecting them to a hydrogenation reaction or by subjecting them to a metathesis reaction and subsequent hydrogenation; (3) a vulcanizable mixture comprising the nitrile rubber or hydrogenated nitrile rubber and at least one crosslinking agent; (4) producing a vulcanizate, comprising subjecting the vulcanizable mixture to crosslinking, preferably by increasing the temperature or photo-chemical activation; and (5) the vulcanizate obtained by the above mentioned method. #CMT#USE : #/CMT# The nitrile rubber is useful for producing vulcanizate. #CMT#ADVANTAGE : #/CMT# The method: produces nitrile rubber with uniform monomer distribution and a lower proportion of long chain branching, thus provides nitrile rubber with improved flow properties and good processing properties; is easy to process; and provides nitrile rubber, which is easy to handle and produces vulcanizates with good mechanical properties. #CMT#INORGANIC CHEMISTRY : #/CMT# Preferred Components: The oxidizing agent used is hydrogen peroxide, peroxodisulfate, peroxodiphosphate hydroperoxide, peracid, peracid ester, peracid anhydride or peroxides with two organic groups, preferably sodium-, potassium- or ammonium salts of peroxodisulfuric or peroxodiphosphoric acid, t-butyl hydroperoxide, cumene hydroperoxide, pinane hydroperoxide, p-menthane hydroperoxide, dibenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide, t-butyl perbenzoate or t-butyl peracetate, preferably pinane hydroperoxide, p-menthane hydroperoxide. The reducing agent used is sodium formaldehyde sulfoxylate, sodium benzaldehyde sulfoxylate, reducing sugar, ascorbic acid, sulfenates, sulfinates, sulfoxylates, dithionite, sulfite, metabisulfite, disulfite, sugar, urea, thiourea, xanthate, thioxanthates, hydrazinium salts, amines and amine derivatives, preferably, aniline, dimethylaniline, monoethanolamine, diethanolamine or triethanolamine, preferably sodium formaldehyde sulfoxylate. #CMT#POLYMERS : #/CMT# Preferred Method: The emulsion polymerization is carried out in the presence of sodium ethylenediaminetetraacetate (EDTA), sodium silicate, sodium pyrophosphate, sodium polyphosphate or trisodium phosphate. The EDTA and iron(II) chloride in the form of iron chloride tetrahydrate are used in the emulsion polymerization. The emulsion polymerization is followed by either (i) a metathesis reaction for the molecular weight degradation, (ii) a metathesis reaction for the molecular weight degradation and subsequent hydrogenation, or (iii) only one hydrogenation. Preferred Components: The vulcanizable mixture further comprises at least one filler. #CMT#EXAMPLE : #/CMT# Butadiene (62 parts by weight), acrylonitrile (38 parts by weight), total water amount (200 parts by weight), Edenor HTiCT(RTM: Selectively hardened tallow fatty acid) (2.20 parts by weight), tertiary dodecyl mercaptan (0.30 parts by weigh), Trigonox NT 50(RTM: P-menthane hydroperoxide) (0.02 parts by weight), premix ferrous chloride (containing the reducing agent Rongalit C(RTM: Sodium salt of a sulfinic acid derivatives) and ferrous salt (ferrous sulfate heptahydrate (0.986 g) or ferrous chloride tetrahydrate (0.845 g)) (0.030 parts by weight) were provided in a autoclave and emulsion polymerization was carried out at 13+- 0.5[deg] C for 7 hours at a polymerization rate of 74.8%. Then polymerization was terminated by adding an aqueous solution of diethylhydroxylamine (0.4 parts by weight). The unreacted monomers and other volatile components were removed by steam distillation. Then prior to the coagulation a 50% dispersion of Vulkanox BKF(RTM: 2-[(2-Hydroxy-5-methyl-3-tert-butyl-phenyl)methyl]-4-methyl-6-tert-butyl-phenol) (0.3 parts by weight) was added. Subsequently the nitrile rubber obtained was coagulated, washed and dried. |
