GB417519A - New synthetic resins and their manufacture - Google Patents

Abstract

The dihydroxybenzophenones employed in the preparation of synthetic resins according to the parent Specification are replaced by the nuclear alkyl compounds, particularly the methyl - substituted dihydroxybenzophenones. Examples are given of the condensation of 3 : 3<1>-dimethyl-2 : 4<1> - and 4 : 4<1>-dihydroxybenzophenones with formaldehyde. Reference is also made to the use of 3 : 3<1>-dimethyl - 2 : 4 - dihydroxybenzophenone and of other aldehydic reactants than formaldehyde, e.g. acetaldehyde, paraformaldehyde, metaformaldehyde and hexamethylenetetramine. The products are used for the same purposes and with the same additions as those described in the parent Specification, the examples of the application of the resins being the same in the two cases. Two features not present in the parent Specification are the use of a small proportion of ammonia for clarifying compositions containing the synthetic resin and the employment of mixed esters of cellulose, e.g. cellulose nitro-nitro-acetate, and ether-esters of cellulose in the manufacture of the compositions. The Specification as open to inspection under Sect. 91 refers to the use of the nuclear substitution derivatives in general of a dihydroxybenzophenone for the preparation of the synthetic resins. It also mentions ethyl cellulose acetate and oxyethyl cellulose acetate as cellulose ether-esters that may be employed in the manufacture of the compositions. This subject-matter does not appear in the Specification as accepted. 3 : 3<1> - Dimethyl - 4 : 4<1> - dihydroxybenzophenone is obtained by condensing o-cresol with carbon tetrachloride in the presence of zinc, aluminium or stannic chlorides and hydrolyzing the product. 3 : 3<1> - Dimethyl - 2 : 4 - dihydroxybenzophenone is prepared from the condensation of m-toluic acid with 1-methyl-2 : 6-dihydroxybenzene in the presence of zinc chloride.