GB426942A - Improvement in colloidising cellulose esters and the manufacture therefrom of highlyflexible sheeting - Google Patents

Abstract

Highly flexible sheetings are prepared by colloidizing cellulose acetate propionate having a propionyl content of at least 10 per cent and in which at least \ba1/2\be per cent and not more than 6 per cent of the combined acyl content of the ester has been hydrolyzed off or replaced by hydroxyl groups with a solvent consisting of a major proportion of propylene chloride and a minor proportion of methyl alcohol and depositing the resultant solution on a film-forming surface. The solvent mixture may contain the methyl alcohol component in a proportion of 10 to 30 per cent. A slightly hydrolyzed cellulose acetate propionate prepared as described in Specification 398,626 and containing 15 per cent propionyl and 26 per cent acetyl may be employed. A plasticizer such as triphenyl phosphate may be present, and in this case it is preferable to strip the films from the forming surfaces before they are completely cured, since in this case the products are of greater flexibility. The proportion of solvent to ester employed may be 5 : 1 or 6 : 1 by weight. Examples are given. Solutions of slightly hydrolyzed cellulose acetate propionate in the solvents specified may also be employed by known methods for artificial silk manufacture, lacquering and overcoating in general, artificial leather &c. Known plasticizers, cellulose esters, resins or other comparable plastic materials may be added if desired in the application of these solutions. The Specification as open to inspection under Sect. 91 comprises also the use of ethyl, normal propyl, isopropyl, normal butyl, isobutyl, tertiary butyl or other lower aliphatic alcohol in place of methyl alcohol. This subject-matter does not appear in the Specification as accepted.ALSO:Compositions comprising a slightly hydrolyzed cellulose acetate propionate in a solvent comprising a major proportion of propylene chloride and a minor proportion of methyl alcohol, if desired together with additions such as triphenyl phosphate to reduce inflammability, known plasticizers, cellulose esters, resins or the like, may be employed by known methods for the manufacture of artificial leather &c. The Specification as open to inspection under Sect. 91 comprises also the use of ethyl, normal propyl, isopropyl, normal butyl, isobutyl, tertiary butyl, or other lower aliphatic alcohols in place of methyl alcohol. This subject-matter does not appear in the Specification as accepted.