Patent GB-767254-A (GB)
Title: Improvements in the vulcanisation of rubber
IPC: C08K5/00
Filed: 1955-03-03
Abstract: Vulcanized synthetic rubber is prepared using as an accelerator a mercaptopyrimidine of the general formula <FORM:0767254/IV(a)/1> in which R1 and R2 may be hydrogen or a lower alkyl radical, and R3 may be hydrogen, an organic radical, the equivalent weight of a metal such as zinc, or the ammonium cation of an organic base.  Thus the accelerator may be either of the mercapto-methylpyrimidines obtained by reacting acetylacetone or the dimethylacetal of acetoacetic aldehyde with thiourea, or a compound obtained by exchanging the hydrogen attached to the sulphur of one of these mercaptomethylpyrimidines by a nitrophenyl, dinitrophenyl, hydroxphenyl, or alkylaminophenyl group by reacting the mercaptomethylpyrimidine with the corresponding chloro compound. Alternatively, it may be a disulphide obtained by the oxidation of a mercaptoalkylpyrimidine by a persulphate or chlorine, or a polysulphide obtained by the reaction of a sodium salt of a mercaptoalkylpyrimidine and sulphur monochloride, or the zinc, cyclohexylamine, diethylamine, morpholine, piperidine, ethylene diamine or phenylene diamine salt of a mercaptoalkylpyrimidine, or the condensation product of a mercaptopyrimidine with formaldehyde and para-phenylene diamine or with formaldehyde and a toluidine.ALSO:A mercapto-pyrimidine for use as a vulcanization accelerator has the general formula <FORM:0767254/IV(b)/1> in which R1 and R2 may be hydrogen or a lower alkyl radical, and R3 may be hydrogen, an organic radical, the equivalent weight of a metal such as zinc, or the ammonium cation of an organic base.  Thus the mercapto-pyrimidine may consist in either of the mercapto-methylpyrimidines obtained by reacting acetyl-acetone or the dimethylacetal of acetoacetic aldehyde with thiourea, or a compound obtained by exchanging the hydrogen attached to the sulphur of one of these mercaptomethylpyrimidines by a nitrophenyl, dinitrophenyl, hydroxyphenyl, or alkylaminophenyl group by reacting the mercaptomethylpyrimidine with the corresponding chloro compound. Alternatively the mercaptopyrimidine may consist in a disulphide obtained by the oxidation of a mercaptoalkylpyrimidine by a persulphate or chlorine, or a polysulphide obtained by the reaction of a sodium salt of a mercapto-alkyl pyrimidine and sulphur-mono-chloride, or in the zinc, cyclohexylamine, diethylamine, morpholine, piperidine, ethylene diamine or phenylene diamine salt of a mercaptoalkylpyrimidine, or in the condensation product of a mercapto-pyrimidine with formaldehyde and para-phenylene diamine or with formaldehyde and a toluidine.ALSO:Vulcanized natural or synthetic rubber is prepared using as an accelerator a mercaptopyrimidine of the general formula:  <FORM:0767254/V/1> in which R1 and R2 may be hydrogen or a lower alkyl radical, and R3 may be hydrogen, an organic radical, the equivalent weight of a metal such as zinc, or the ammonium cation of an organic base.  Thus the accelerator may consist in either of the mercapto methylpyrimidines obtained by reacting acetylacetone or the dimethylacetal of acetoacetic aldehyde with thiourea, or a compound obtained by exchanging the hydrogen attached to the sulphur of one of these mercaptomethylpyrimidines by a nitrophenyl, dinitrophenyl, hydroxyphenyl, or alkylaminophenyl group by reacting the mercaptomethyl pyrimidine with the correspondingchloro compound. Alternatively the accelerator may consist in a disulphide obtained by the oxidation of a mercaptoalkylpyrimidine by a persulphate or chlorine, or a polysulphide obtained by the reaction of a sodium salt of a mercaptoalkyl pyrimidine and sulphur monochloride, or in the zinc, cyclohexylamine, diethylamine, morpholine, piperidine, ethylene diamine or phenylene diamine salt of a mercaptoalkylpyrimidine, or in the condensation product of a mercapto-pyrimidine with formaldehyde and para-phenylene diamine or with formaldehyde and a toluidine.  In one of the examples a vulcanizable mixture is prepared by adding as accelerator 0,8 parts cyclohexylamine salt of 2 mercapto-4-methylpyrimidine to 50 parts by weight pale crepe, 50 parts smoked sheets, 10 parts zinc oxide, 3 parts sulphur, and 1,5 parts stearic acid, and the mixture is vulcanized at 134 DEG C. for 35 minutes.  The accelerators specified in the other examples are (1) the reaction product of 2-mercapto-4-methylpyrimidine, formaldehyde, and paraphenylencdiamine, (2) 2-mercapto-4-methylpyrimidine, (3) 4, 6 dimethy-2-mercaptopyrimidine disulphide, (4) the zinc salt of 2-mercapto-4-methylpyrimidine, and (5) the diethylamine salt of 2-mercapto-4-methylpyrimidine.