GB531842A - Improvements relating to the manufacture of moulded bodies from cellulose esters - Google Patents

Abstract

531,842. Treating cellulose ester articles. I. G. FARBENINDUSTRIE AKT.-GES. Aug. 3, 1939, No. 22526. Convention date, Aug. 3, 1938. [Class 2 (ii)] Thick walled moulded bodies consisting of cellulose esters and made from solutions of such esters in aliphatic chlorohydrocarbons or in solutions containing such hydrocarbons, or made by uniting several moulded bodies by means of aliphatic chlorohydrocarbons or solutions containing such chlorohydrocarbons are stabilized by treating them with a liquid which dissolves out residual aliphatic chlorohydrocarbons but has no solvent action on the cellulose ester. Methylene chloride, chloroform, ethylene chloride, ethyl chloride, propyl chloride, or tetrachlorethane alone or mixed with methyl or ethyl alcohol, acetone or benzene may be used as solvents or adhesives in the production of the moulded bodies. The cellulose esters used include cellulose triacetate, acetonesoluble cellulose acetate, cellulose propionate, and cellulose acetobutyrate. The moulded body may be dried before being treated with the extracting agent. The composition of the extracting liquid may be such that it exerts a feeble swelling effect. In an example, a cellulose triacetate film is obtained by casting from a solution containing methylene chloride, and a tube is made by winding the film and securing the layers by means of a solution of cellulose triacetate. The tube is subjected to drying conditions for several days and then the residual solvent is removed by immersing the tube in a mixture of acetone and methyl alcohol. The tube is then subjected to intense drying while supported on a rod. In another example a tube is made by extruding a cellulose triacetate solution containing methylene chloride through an annular orifice and setting by cooling to 0‹C. or lower. After drying the tube is treated with a mixture of acetone and methyl alcohol. In another example, a cellulose acetate plate containing residual methylene chloride is treated with a mixture of acetone and methyl alcohol.