Patent GB-781768-A (GB)
Title: Improvements in or relating to rubber deterioration retarders
IPC: C08K5/13
Filed: 1954-07-21
Abstract: An antioxidant for synthetic rubber comprises the reaction product of a tertiary olefin containing 4 to 8 carbon atoms or a mixture of such olefins, and a bis-phenol of the formula <FORM:0781768/IV (a)/1> wherein R1 is an alkyl hydrocarbon radical containing 1 or 2 carbon atoms and R2 is an alkyl hydrocarbon radical containing 1 to 4 carbon atoms, the bis-phenol and the olefin or olefins being supplied to the reaction in a molar ratio of 1 : 3.5 to 4.75, and the reaction product being a mixture of alkylated bis-phenol alkanes containing 1 to 4 tertiary olefin groups added to the aryl portion of the bis-phenol molecule ortho to a hydroxyl group.  The tertiary olefin may comprise isobutylene, isoamylene, 2-methylpentene-1, 2-ethyl-propene-1, 2-ethyl-pentene-1, 2-methyl-hexene-1, or di-isobutylene.  The bisphenol is preferably 2,2-bis-(4-hydroxyphenyl) propane, or may consist in 2,2-bis-(4-hydroxyphenyl) butane, 3,3-bis-(4-hydroxyphenyl) pentane, 2,2-bis-(4-hydroxyphenyl) pentane, 2,2-bis - (4 - hydroxy - phenyl) hexane, 2,2 - bis - (4 - hydroxyphenyl) 4 - methyl pentane, 3,3-bis - (4 - hydroxyphenyl) hexane, 3,3 - bis - (4-hydroxyphenyl) heptane, 3,3-bis-(4-hydroxyphenyl)-4-methyl hexane, 3,3-bis-(4-hydroxyphenyl) - 5 - methyl hexane, or 3,3 - bis - (4 - hydroxyphenyl) - 3,4 - dimethyl pentane.  The alkylated bis-phenol may be used as an antioxidant for synthetic rubbers, both vulcanized and unvulcanized, e.g. polymers of butadiene, isoprene, dimethylbutadiene, chlorobutadiene, fluorobutadiene, cyanobutadiene and their copolymers with each other or with the styrenes, acrylonitriles, acrylic and methacrylic acid and their esters, vinylidene chloride, vinyl pyridine, vinyl esters and vinyl alkyl ethers.  The amount of alkylated bis-phenol employed is preferably 0.1 to about 10 per cent by weight of the natural or synthetic rubber.  The antioxidant may be incorporated in synthetic rubber by adding it in aqueous dispersion or emulsion to a latex of synthetic rubber prior to coagulation.ALSO:An antioxidant for natural or synthetic rubber comprises the reaction product of a tertiary olefin containing 4 to 8 carbon atoms or a mixture of such olefins, and a bis-phenol of the formula: <FORM:0781768/IV (a)/1> wherein R1 is an alkyl hydrocarbon radical containing 1 or 2 carbon atoms and R2 is an alkyl hydrocarbon radical containing 1 to 4 carbon atoms, the bis-phenol and the olefin or olefins being supplied to the reaction in a molar ratio of 1:3.5 to 4.75 and the reaction product being a mixture of alkylated bis-phenol alkanes containing 1 to 4 tertiary olefin groups added to the aryl portion of the bis-phenol molecule ortho to a hydroxyl group.  The tertiary olefin may comprise isobutylene, isoamylene, 2-methyl pentene-1,2 ethyl propene 1,2-ethyl pentene 1,2-methyl hexene-1, or di-isobutylene.  The bisphenol is preferably 2,2 bis (4 hydroxyphenyl) propane, or may consist in 2,2 bis (4-hydroxyphenyl) butane, 3,3 bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxyphenyl) pentane, 2,2 bis (4-hydroxy-phenyl) hexane, 2,2-bis (4-hydroxyphenyl) 4-methyl pentane, 3,3-bis (4 hydroxyphenyl) hexane, 3,3 bis (4-hydroxyphenyl) heptane, 3,3 bis (4-hydroxy-phenyl) 4-methyl hexane, 3,3 bis (4-hydroxyphenyl) 5-methyl hexane, or 3,3 bis (4-hydroxyphenyl) 3,4 dimethyl pentane.  The alkylated bis-phenol is prepared by reacting the bis-phenol and the tertiary olefin in the presence of an acidic condensation catalyst in an organic solvent, e.g. hexane, heptane, benzene, or toluene at a temperature above 50 DEG  C., e.g. 65 DEG  to 85 DEG  C.  The catalyst may comprise sulphuric acid, paratoluene sulphonic acid, boron trifluoride, or acid activated clay containing over 50 per cent aluminium silicate, and the amount of catalyst is preferably 0.5 to 10 per cent by weight of the bis-phenol reactant.  The reaction mixture is in the ratio of about 4 mols. of tertiary olefin to 1 mol. of bis-phenol in order to obtain a higher proportion of tetra-substituted than of di- and mono-substituted alkylated bis-phenol, the former being a more effective anti-oxidant.  In order to counteract the tendency of the reaction product to crystallize during storage the reaction mixture may comprise a small amount of an aryl-substituted alkenyl hydrocarbon of the general formula: <FORM:0781768/IV (a)/2> where Ar is an aryl hydrocarbon, B is an alkylidene radical, n is a digit from 1 to 5, and R is a hydrogen atom or an alkyl radical, e.g. styrene, a-methyl styrene, p-methyl styrene, ethyl styrene, alkyl benzene, alkyl naphthalene, or vinyl naphthalene. Alternatively, an excess of tertiary olefin such as isobutylene may be used in the reaction so that some of the olefin forms a trimer such as tri-isobutylene which has an anti-crystallizing effect.  The reaction may be carried out in an inert atmosphere of nitrogen in an autoclave in which is placed the organic solvent, the bis-phenol, and the acidic catalyst.  The mixture is stirred vigorously while heating to a temperature of about 70 DEG C., and a gaseous tertiary olefin is introduced, preferably over a five-hour period.  If an acid activated clay catalyst is employed the reaction product is filtered therefrom and the solvent removed. If sulphuric acid is used as catalyst it is neutralized with an alkali at the end of the reaction.  The resulting alkylated bis-phenol product may be used as an antioxidant for all kinds of natural and synthetic rubbers, both vulcanized and unvulcanized, especially for conjugated diene derivatives, and copolymers thereof with monoolefins.  In an example 46 grams of 2,2-bis (4-hydroxy-phenyl) propane is suspended in 350 ml. of benzene and 2.3 grams of 97 per cent sulphuric acid added thereto.  The mixture is heated to and maintained at 70 DEG  C. and about 40 grams isobutylene introduced over a 5.5-hour period.  The benzene solution of the reaction product is then washed with sodium hydroxide solution and water, and the benzene removed by distillation.  The reaction product comprises mono, di, and higher tertiary butylated bis-phenols, and is compounded with natural rubber together with vulcanizing ingredients. Further examples are described illustrating the use of acid-activated clay as catalyst, and the addition of styrene to the reaction mixture.ALSO:An antioxidant for natural or synthetic rubber comprises the reaction product of a tertiary olefin containing 4 to 8 carbon atoms or a mixture of such olefins, and a bis-phenol of the formula: <FORM:0781768/V/1> wherein R1 is an alkyl hydrocarbon radical containing 1 or 2 carbon atoms and R2 is an alkyl hydrocarbon radical containing 1 to 4 carbon atoms, the bis-phenol and the olefin or olefins being supplied to the reaction in a molar ratio of 1 : 3,5 to 4,75, and the reaction product being a mixture of alkylated bis-phenol alkanes containing 1 to 4 tertiary olefin groups added to the aryl portion of the bis-phenol molecule ortho to a hydroxyl group.  The tertiary olefin may comprise isobutylene, isoamylene, 2 methyl pentene-1, 2 ethyl propene 1, 2-ethyl pentene 1, 2-methyl hexena-1, or di-isobutylene.  The bis-phenol is preferably 2, 2 bis (4 hydroxyphenyl) propane, or may consist in 2, 2 bis (4-hydroxyphenyl) butane, 3, 3 bis (4-hydroxyphenyl) pentane, 2, 2-bis (4-hydroxyphenyl) pentane, 2, 2 bis (4-hydroxy-phenyl) hexane, 2, 2-bis (4-hydroxyphenyl) 4-methyl pentane, 3, 3-bis (4 hydroxyphenyl) hexane, 3, 3 bis (4 hydroxyphenyl) heptane, 3, 3 bis (4 hydroxyphenyl) 4 methyl hexane, 3, 3 bis (4 hydroxyphenyl) 5 methyl hexane, or 3, 3 bis (4 hydroxyphenyl) 3, 4 dimethyl pentane. The alkylated bis-phenol is prepared by reacting the bisphenol and the tertiary olefin in the presence of an acidic condensation catalyst in an organic solvent, e.g. hexane, heptane, benzene, or toluene at a temperature above 50 DEG C., e.g. 0,65 DEG  to 85 DEG C. The catalyst may comprise sulphuric acid, paratoluene sulphonic acid, boron trifluoride, or acid activated clay containing over 50 per cent aluminium silicate, and the amount of catalyst is preferably 0,5 to 10 per cent by weight of the bis-phenol reactant.  The reaction mixture is in the ratio of about 4 mols of tertiary olefin to 1 mol of bis-phenol in order to obtain a higher proportion of tetrasubstituted than of di- and mono-substituted alkylated bis-phenol, the former being a more effective anti-oxidant.  In order to counteract the tendency of the reaction product to crystallize during storage the reaction mixture may comprise a small amount of an aryl-substituted alkenyl hydrocarbon of the general formula: <FORM:0781768/V/2> where Ar is an aryl hydrocarbon, B is an alkylidene radical, n is a digit from 1 to 5, and R is a hydrogen atom or an alkyl radical, e.g. styrene, a -methyl styrene, p-methyl styrene, ethyl styrene, alkyl benzene, alkyl naphthalene, or vinyl naphthalene. Alternatively an excess of tertiary olefin such as isobutylene may be used in the reaction so that some of the olefin forms a trimer such as tri-isobutylene which has an anticrystallizing effect. The reaction may be carried out in an inert atmosphere of nitrogen in an autoclave in which is placed the organic solvent, the bis-phenol, and the acidic catalyst.  The mixture is stirred vigorously while heating to a temperature of about 70 DEG C., and a gaseous tertiary olefin is introduced, preferably over a five hour period.  If an acid activated clay catalyst is employed the reaction product is filtered therefrom and the solvent removed. If sulphuric acid is used as catalyst it is neutralized with an alkali at the end of the reaction.  The resulting alkylated bis-phenol product may be used as an antioxidant for all kinds of natural and synthetic rubbers, both vulcanized and unvulcanized, especially for conjugated diene derivatives, and copolymers thereof with mono-olefins.  The amount of alkylated bisphenol employed is preferably 0,1 to about 10 per cent by weig