| 摘要 |
Continuous transparent flexible sheets or films are made by disposing a layer comprising finely divided cellulose derivative between two moving bands and colloidizing the layer under heat and pressure. Examples of powdered compositions are cellulose acetate and dimethyl phthalate, hydrolyzed cellulose acetate, propionate and dimethyl phthalate, and hydrolized cellulose acetate butyrate and diethyl phthalate. Suitable apparatus is described in Specification 482,979. One or both of the moving bands may have a roughened surface. |
