GB642827A - Processes of producing condensation products of phenols and processes of preserving rubber - Google Patents

Abstract

Condensation products are obtained by reacting one molecular proportion of a polyhydric phenol such as hydroquinone resorcinol, and catechol, with two mols. of a polyhydric alcohol having two hydroxy groups linked to separate carbon atoms separated by one intervening carbon atom, in the presence of an acidic condensation catalyst such as aluminium chloride, zinc chloride, phosphoric acid and sulphuric acid. Suitable polyhydric alcohols are the 1 : 3- and 2 : 4-dihydroxy alkanes. The products are used as antioxidants in rubber including rubber-like copolymers of butadiene-1 : 3 with styrene or acrylic nitrile. In examples 2-methyl-2 : 4-pentane diol is condensed with: (1) hydroquinone; (2) resorcinol; (3) catechol; giving products which range from oily liquids to soft resins. The Specification as open to inspection under Sect. 91 includes also the use as the phenolic component phenol, o-chlorphenol, p-tertiary butyl phenol, p-methoxy phenol, b -naphthol, the xylenols, thymol and cravacrol. An example of the interaction of phenol with 2-methyl-2 : 4-pentane diol in the presence of zinc chloride is also included. This subject-matter does not appear in the Specification as accepted.ALSO:Condensation products are obtained by reacting 2 molecular proportions of a polyhydric phenol such as hydroquinone, resorcinol and catechol with two mols. of a polyhydric alcohol having two hydroxy groups linked to separate carbon atoms separated by one intervening carbon atom, in the presence of a condensation catalyst such as aluminium chloride, zinc chloride, phosphoric acid and sulphuric acid. Suitable polyhydric alcohols are the 1 : 3- and 2 : 4-dihydroxy alkanes. The products are used as antioxidants in rubber. In examples: (1) 2-methyl-2 : 4-pentane diol is condensed with hydroquinone in petroleum solvent in the presence of sulphuric acid giving a thick, dark amber liquid; (2) 2-methyl-2 : 4-pentane diol is condensed with resorcinol as in (1); (3) catechol is used in place of resorcinol in the process of (2). Rubber compositions containing the products as anti-oxidants are described. The Specification as open to inspection under Sect. 91 includes also the use as the phenolic component phenol, o-chlor-phenol, p-tertiary-butyl phenol, p-methoxy phenol, b -naphthol, the xylenols, thymol and carvacrol. An example of the interaction of phenol 2-methyl-2 : 4-pentane diol in the presence of zinc chloride is also included. This subject-matter does not appear in the Specification as accepted.ALSO:A method of preserving rubber comprises treating a rubber with a condensation product of one molecular proportion of a polyhydric phenol with two molecular proportions of a polyhydric alcohol having hydroxy groups linked to separate carbon atoms and separated by one intervening carbon atom produced in the presence of an acid condensation catalyst. Suitable phenols are hydroquinone resorcinol and catechol. Suitable alcohols are the 1 : 3-and 2 : 4-alkane diols. Rubbers which may be stabilized include India rubber, reclaimed rubber, balata, gutta percha and copolymers of butadiene with styrene or acrylonitrile. In examples there are described rubber compositions containing zinc oxide, lithopone, sulphur, diphenyl guanidine phthalate, benzoyl thio benzothiazole and paraffin and containing as antioxidants the condensation products of (1) hydroquinone and 2-methyl-2 : 4-pentane diol; (2) resorcinol and 2-methyl-2 : 4-pentane diol, and (3) catechol and 2-methyl-2 : 4-pentane diol. Tests are quoted to show the efficiency of the anti-oxidants. The Specification as open to inspection under Sect. 91 includes also the use as the phenolic components phenol, o-chlor-phenol, p-tertiary butyl phenol, p-methoxy-phenol, b -naphthol, the xylenols, thymol and carvacrol. An example of the interaction of phenol with 2-methyl-2 : 4-pentane diol in the presence of zinc chloride is also included. This subject-matter does not appear in the Specification as accepted.