Patent GB-787221-A (GB)
Title: Improvements in or relating to the preparation of vulcanized natural or synthetic rubber products
IPC: C08K5/14
Filed: 1956-02-10
Abstract: Peroxides for use as vulcanization agents (see Group V) have either (a) the formula <FORM:0787221/IV (b)/1> or (b) the formula <FORM:0787221/IV (b)/2> wherein R and R1 are either saturated or aromatically unsaturated hydrocarbon radicals, R1 is an aryl radical, R2 and R3 are either hydrogen or alkyl radicals of less than 4 carbon atoms, and R4 is a p-menthyl, pinanyl, or carenyl radical.  Peroxides of the formula (a) may be prepared by reacting a hydroperoxide such as cumene, p-cymene, p-di-isopropylbenzene, 1-phenylcyclohexyl, p-menthane, isopropylnaphthalene, 1-methylcyclohexyl, pinane, t-butyl, or t-amyl hydroperoxide with a vinyl ether such as dihydro-a -terpinyl, bornyl, isobornyl, fenchyl, dehydroabietyl, cyclohexyl, 1-methylcyclohexyl, methyl, ethyl, n-butyl, isobutyl, t-butyl, stearyl, or phenyl vinyl ether, in the presence of a catalyst, e.g. of the FriedelCrafts type, or a mineral or organic sulphonic acid, or an acid clay, and in a non-aqueous medium, e.g. an inert solvent such as benzene or hexane.  In one of the examples a -dihydroterpinyl ethyl a -cumyl peroxide is prepared by adding gaseous borontrifluoride to a watercooled solution in dry benzene of dihydroterpinyl vinyl ether and cumene hydroperoxide.  Peroxides of the formula <FORM:0787221/IV (b)/3> may be prepared by a condensation reaction between an alcohol of the formula <FORM:0787221/IV (b)/4> and a hydroperoxide of the formula R4-OOH.  The aryl group R1 may be phenyl, naphthyl, anthryl, phenanthryl or methylphenyl and the alcohols specified are a ,a -dimethylbenzyl, a -methylbenzyl, a ,a  - dimethyl - p - methylbenzyl, and a ,a -dimethyl-p-isopropyl-benzyl alcohols.  In one example, p-menthyl (a ,a -dimethylbenzyl) peroxide is prepared by heating to 75 DEG  C. a mixture of a ,a -dimethylbenzyl alcohol, p-menthane, hydroperoxide, and p-toluene sulphonic acid monohydrate.  Other examples describe the preparation of peroxides by reacting a ,a -dimethylbenzyl alcohol and pinane and D 3-carene hydroperoxide, respectively, and by reacting a ,a -trimethylbenzyl alcohol and p-menthane hydroperoxide.ALSO:Natural or synthetic rubber is vulcanized by heating it with 0.1 to about 10 per cent by weight of the rubber of an organic peroxide of the formula <FORM:0787221/IV (a)/1> wherein R and R1 are either saturated or aromatically unsaturated hydrocarbon radicals, R1 is an aryl radical, R2 and R3 are either hydrogen or alkyl radicals of less than 4 carbon atoms, and R4 is a p-methyl, pinanyl, or carenyl radical.  The peroxide of the formula <FORM:0787221/IV (a)/2> as cumene, p-cymene, p-di-isopropylbenzene, 1 - phenylcyclohexyl, p - menthane, isopropylnaphthalene, 1-methylcyclohexyl, pinane, t-butyl, or t-amyl hydroperoxide with a vinyl ether such as dihydro-a -terpinyl, bornyl, isobornyl, fenchyl, dehydroabietyl, cyclohexyl, 1-methylcyclohexyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, stearyl, or phenyl vinyl ether, in the presence of a catalyst, e.g. of the Friedel-Crafts type, or a mineral or organic sulphonic acid, or an acid clay, and in a non-aqueous medium, e.g. an inert solvent such as benzene or hexane.  The peroxide of the formula <FORM:0787221/IV (a)/3> between an alcohol of the formula <FORM:0787221/IV (a)/4> and a hydroperoxide of the formula R4-OOH. The aryl group R1 may be phenyl, naphthyl, anthryl, phenanthryl, methylphenyl, &c., and the alcohols specified are a ,a -dimethylbenzyl, a  - methylbenzyl, a ,a  - dimethyl - p - methyl - benzyl, and a ,a -dimethyl-p-isopropyl-benzyl alcohols. Examples are described in which peroxides are prepared by reacting a ,a -dimethylbenzyl alcohol and p-menthane, pinane, and D 3-carene hydroperoxide, respectively, and by reacting a ,a -trimethylbenzyl alcohol and p-menthane hydroperoxide.  The synthetic rubbers which may be vulcanized include polmerized diolefins, e.g. isoprene and dimethyl butadiene, halogenated or other substituted diolefins, e.g. chloroprene and copolymers of diolefins with styrene, acrylic acid esters, and acrylonitrile. Other examples illustrate the vulcanization of GRS synthetic rubber by heating with isobutylethyl p-menthyl peroxide, and dihydro-a -terpinylethyl a -cumyl peroxide, of natural rubber and GRS synthetic rubber by heating with dihydro-a -terpinylethyl-a -cumyl, dihydro - a  - terpinylethyl - p - menthyl, diethyl-p - menthyl, isobutyl - ethyl - a  - cumyl, isobutyl - ethyl - p - menthyl, and n - butyl - ethyl p-menthyl peroxides, respectively, of butadiene-acrylonitrile and dihydro-a -terpinyl-ethyl-a -cumyl and dihydro-a -terpinyl-ethyl-p-menthyl peroxides, respectively, and of GRS synthetic rubber and p-menthyl (a ,a -dimethylbenzyl) peroxide.ALSO:Natural or synthetic rubber is vulcanized by heating it with 0,1 to about 10 per cent by weight of the rubber of an organic peroxide of the formula:  <FORM:0787221/V/1> or <FORM:0787221/V/2> wherein R and R1 are either saturated or aromatically unsaturated hydrocarbon radicals, R1 is an aryl radical, R2 and R3 are either hydrogen or alkyl radicals of less than 4 carbon atoms, and R4 is a p-menthyl, pinanyl, or carenyl radical.  The peroxide of the formula:  <FORM:0787221/V/3> may be prepared by reacting a hydroperoxide such as cumene, p-cymene, p-di-isopropylbenzene, 1-phenyl cyclohexyl, p-menthane, isopropylnaphthalene, 1-methylcyclohexyl, pinane, t-butyl, or t-amyl hydroperoxide with a vinyl ether such as dihydro-a -terpinyl, bornyl, isobornyl, fenchyl, dehydroabietyl, cyclohexyl, 1-methylcyclohexyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, stearyl, or phenyl vinyl ether, in the presence of a catalyst, e.g., of the Friedel-Crafts type, or a mineral or organic sulphonic acid, or an acid clay, and in a non-aqueous medium, e.g., an inert solvent such as benzene or hexane.  The peroxide of the  formula: <FORM:0787221/V/4> may be prepared by a condensation reaction between an alcohol of the formula:  <FORM:0787221/V/5> and a hydroperoxide of the formula R4-OOH.  The aryl group R1 may be phenyl, naphthyl, anthryl, phenanthryl, methylphenyl, &c., and the alcohols specified are a , a  dimethylbenzyl, a -methylbenzyl, a , a -dimethyl-p-methylbenzyl, and a , a -dimethyl-p-isopropyl-benzyl alcohols.  Examples are described in which peroxides are prepared by reacting a , a  dimethylbenzyl alcohol and p-menthane, pinane, and D 3 carene hydroperoxide, respectively, and by reacting a , a trimethylbenzyl alcohol and p-menthane hydroperoxide.  The synthetic rubbers which may be vulcanized include polymerized diolefins, e.g., isoprene and dimethyl butadiene halogenated or other substituted diolefins, e.g. chloroprene, and copolymers of diolefins with styrene, acrylic acid esters, and acrylonitrile. Other examples illustrate the vulcanization of CRS synthetic rubber by heating with isobutylethyl p-menthyl peroxide, and dihydro-a -terpinylethyl a -cumyl peroxide, of natural rubber and CRS synthetic rubber by heating with dihydro - a  - terpinylethyl - a  - cumyl, dihydro - a - terpinylethyl - p - menthyl, diethyl - p - menthyl, isobutyl - ethyl - a  - cumyl, isobutyl - ethyl - p - menthyl, and n - butyl ethyl p - menthyl peroxides, respectively, of butadiene-acrylonitrile and dihydro - a  - terpinyl-ethyl -a  - cumyl and dihydro - a  - terpinyl - ethyl - p - menthyl peroxides, respectively, and of GRS synthetic rubber and p - menthyl (a , a  - dimethylbenzyl) peroxide.