Patent GB-552010-A (GB)
Title: Process for re-utilizing waste moistureproofed regenerated cellulose
IPC: C08J11/08
Filed: 1941-06-05
Abstract: 552,010. Recovering regenerated cellulose &c. from waste materials. SYLVANIA INDUSTRIAL CORPORATION. June 5, 1941, No. 7112. Convention date, June 24, 1940. [Class 2 (i.i)] Waste regenerated cellulose pellicles, such as waste films or foils, softened with glycerine or the like and provided with a moistureproof coating, are subjected to a continuous recovery process which comprises treatment with a liquid which is a solvent for the moistureproof composition but is a non-solvent for the glycerine or other softening agent, whereby the moistureproof composition is removed, and treatment with a solvent for the softening agent. The recovered regenerated cellulose, the recovered coating composition, and the recovered softening agent are utilized in the manufacture of plasticized moistureproofed cellulose pellicles. The waste material may be in the form of strips, scraps, trimmings, and imperfect pieces obtained in the manufacture of films and the like. The regenerated cellulose may be derived from viscose or from cellulose nitrate or other ester by de-esterification, or it may be obtained by precipitation from solutions of cellulose in inorganic or organic solvents. The softener may be glycerine, glycol, or diethylene glycol. The moistureproof composition may comprise a lacquer base such as a cellulose derivative, a plasticizer, a wax, and a wax-blending agent. As shown, viscose from tank 10 is formed into a film in tank 11. The regenerated cellulose is washed, purified, and finally softened with glycerine solution in bath 12. The sheet is dried and then passed to coating machine 14. The waterproofed sheet is cut and trimmed, and the waste material from these operations is passed to shredder 16. A batch of shredded material is treated with a mixture of toluene and butyl acetate or other solvent for the moistureproof composition in the extractor 17, and the used solvent is passed to tank 19. The batch is treated with more solvent and the mass is dropped into cooker 21. Whilst this mixture is standing in the cooker, a second batch of material is fed to extractor 17. The solvent and extracted composition from cooker 21 is passed into extractor 17 and after it has removed some composition from the second batch, it is passed to storage tank 19. Pure solvent from tank 18 passes to extractor 17 and passes with the second batch to cooker 21. After the extraction, the solvent passes to a third batch of material in extractor 17. The batches in cooker 21 are now treated with steam from boiler 23. Steam and residual solvent are condensed and passed to separator 25. The material in cooker 21 is treated with hot water to remove the glycerine. The water is passed twice through the material and the dilute glycerine solution obtained is concentrated in tank 29 and then passed to the storage tank 13 and utilized in softening the freshly formed film. The residual waste material is conveyed to drier 30 and then to storage bin 36. It is utilized in the production of viscose or other cellulosic solutions and of films therefrom. The solution of waterproof composition in tank 19 is passed to tank 15 and utilized in coating the film.