GB825603A - Improvements in bis-phenol-ketone condensation products and rubber compositions containing same - Google Patents

Abstract

A condensation product from 1 mol. of a bis (3-methyl-4-hydroxyphenyl) alkane in which the alkylidene radical has 3-10 carbon atoms or is saturated and cyclic with 4-10 carbon atoms and 1.1 to 2.0 mols. of a ketone having 3-10 carbon atoms is incorporated into rubber prior to vulcanization to prevent discoloration and oxidation. The term rubber includes natural and synthetic unsaturated rubbery polymers. A number of typical diene synthetic rubbers are specified. Suitable substituted alkanes mentioned are 2,2-bis (3-methyl-4-hydroxyphenyl) propane and 1,1-bis (3-methyl-4-hydroxyphenyl) cyclohexane. Others may be prepared by acid condensation of o-cresol with a suitable ketone. Suitable ketones for reaction with the substituted alkanes are acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, ethyl propyl ketone, methyl butyl ketone, cyclopentanone, cyclohexanone, cycloheptanone, cyclo - octanone, cyclodecanone, methyl cyclopentyl ketone, ethyl cyclopentyl ketone, and methyl or ethyl cyclohexyl ketone. Condensation is preferably effected in presence of an acid agent, e.g. sulphuric or hydrochloric acid, aluminium or calcium chloride, if desired with a catalyst such as b -mercapto-propionic acid. Reaction may be in an inert liquid, e.g. acetic acid, benzene, hexane, chlorobenzene or gasoline. The products are preferably added to rubber in proportions of 0.1 to 10% by weight. In the examples: (I) a condensate is prepared from 2.2 - bis (3 - methyl - 4 - hydroxyphenyl) propane and acetone in presence of conc. HCl and some b -mercaptopropionic acid. The product was mixed with natural rubber, channel black, zinc oxide, stearic acid sulphur, and benzothiazyl disulphide and cured. Comparison was made with similar stocks containing no antioxidant or containing phenyl-b -naphthyl amine. (II) The antioxidant is prepared from 2.2 - bis (3 - methyl - 4 - hydroxyphenyl) propane and cyclohexanone. It is tested in the same tyre tread mix as was used in Example (1) and both antioxidants were also tested in a white sidewall rubber composition containing inter alia titanium dioxide and ultramarine blue. Example (III): an antioxidant was prepared from 1,1-bis (3-methyl-4-hydroxyphenyl cyclohexane and acetone.