Patent GB-363700-A (GB)
Title: Process for the preparation of artificial silk and other artificial products from acetyl cellulose
IPC: C08B3/06
Filed: 1930-08-14
Abstract: For the manufacture of artificial silk, films, plastic masses, varnishes, &c., there are used primary triacetyl celluloses made by acetylation processes in which the fibrous structure of the cellulose is preserved and in which the catalyst is a halogen, a halogen hydride acid, a perhalogen acid or a salt of such acid other than an alkali salt except in the presence of a suitable acid, or a halogen fatty acid. By employing the stated catalysts under the specified conditions which avoid the use of sulphuric acid or other catalysts which introduce residues leading to the decomposition of the acetylated cellulose, there are obtained acetates which can be worked up into products having keeping qualities equal to those made from acetone-soluble secondary acetates, and superior thereto as regards strength, resistance to the action of water, the absence of shrinkage when dried, and heat and electrical insulating qualities. Other precautions to be observed during the acetylation are the prevention of temperature differences in the reaction mass, and the avoidance of high temperatures particularly in the early stages of the acetylation; and it is desirable that the cellulose should be treated with swelling agents such as acetic acid, prior to or during the acetylation. For preserving the fibrous structure of the cellulose, there may be added to the reaction mass cyclohexanol acetate, toluene or other hydrocarbons, halogenated hydrocarbons, and ethyl acetate. In examples, cotton wool is treated with acetic acid, is then centrifuged, and is acetylated with a mixture of acetic anhydride, acetic acid, toluene and perchloric acid, the acetylated product is dissolved in methylene chloridealcohol, and the solution worked up into artificial silk, films, etc.; cotton, after treatment with acetic acid, is acetylated by a mixture of acetic anhydride, acetic acid, zinc perchlorate and cyclohexanol acetate, artificial silk &c. is made from a solution of the product in methylene chloride-alcohol; cotton, after treatment with acetic acid, is acetylated by a mixture of acetic anhydride, cyclohexanol acetate, monochloracetic acid and sulphurous acid --a solution of the product in chloroform-alcohol or methylene chloride-alcohol is worked up into wrapping sheets; linters are acetylated in a mixture of acetic anhydride, acetic acid, cyclohexanol acetate, hydrochloric acid, and sulphurous acid--the product is made up into varnishes with the addition of chloroform and tetrachlormethane. The Provisional Specification contains examples in which cotton is acetylated with a mixture of acetic anhydride, cyclohexanol acetate, sulphur dioxide and zinc perchlorate--a solution of the product in methylene chloride-methyl alcohol with the addition of a -chlor-b -hydroxy butyric nitrile is worked up into plastic masses; and in which a solution for the manufacture of artificial threads contains an addition of salicyclic acid nitrile. Specification 312,242, [Class 2 (ii), Cellulose &c.], is referred to.ALSO:The Provisional Specification describes the pro duction of plastic masses from a primary triacety cellulose using as a solvent methylene chloridemethyl alcohol and an addition of a -chlor-b -hydroxybutyric nitrile.