Patent GB-289853-A (GB)
IPC: C08B3/08
Filed: 1928-05-01
Abstract: 289,853. Kodak, Ltd., (Assignees of Clarke, H. T., and Malm, C. J.). May 4, 1927, [Convention date]. Cellulose carboxylates.-Cellulose esters containing acyl groups derived from one or more unsaturated organic acids containing an ethylenic bond, particularly acids of the acrylic series, and substituted acids derived therefrom such as cinnamic acid, are obtained by heating cellulose with the unsaturated acid or acids in the presence of an inert solvent. It is preferred to use a reverted cellulose such as is produced by the viscose or cuprammonia process, or cellulose which has been mercerized and has been treated, as by dehydration, so as to leave the surface in a reactive condition. The esters obtained may be in the fibrous state or in solution, and they may be used as such or they mav be further esterified by known methods of introducing saturated acyl groups, such as those of the corresponding fatty acids, and the. single or mixed esters may be converted into substituted saturated esters, for example by bromination and chlorination of the esters in solution in chloroform. The halogenated esters show a pronounced resistance to burning. In examples, cuprammonium cellulose fibres are treated with cretonic acid dissolved in chlorbenzene, the latter being distilled off with the water from time to time and then replaced by the dry solvent, the product finally obtained being a lower cellulose crotonate; the product of the previous example is acetylated'in the usual manner to pro. duce a cellulose acetocrotonate; cotton which has been mercerized, washed and freed from water by washing with alcohol and ether, and finally dried, is heated with crotonic acid and chlorbenzene as in the first example. The products are suitable for the manufacture of films and varnishes. The Specification as open to inspection under Sect. 91 (3) (a) refers also to the employment of an impeller, such as chloracetic anhydride, in the esterification processes as described in Specification 287,880, as open to inspection under Sect. 91 (3) (a), and to the introduction of one or more other acyl groups simultaneously with the unsaturated groups. In examples, cotton tissue paper is warmed with cinnamic acid or crotonic acid, chloracetic anhydride, and magnesium perchlorate, to give a solution from which cellulose cinuamate or crotonate is precipitated by methyl alcohol; cotton tissue paper is warmed with undecylenic acid or crotonic acid, chloracetic acid, acetic anhydride, and magnesium perchlorate, to give a solution from which a cellulose acetoundecylenate or aceto-crotonate is precipitated by methyl alcohol; to a solution of cellulose cinnamate or crotonate in chloroform, a solution of bromine in the same solvent is added, and the resulting bromo ester precipitated by the addition of methyl alcohol; cotton tissue paper is warmed with stearic acid, crotonic acid, chloracetic anhydride, and magnesium perchlorate, to produce a cellulose crotonate-stearate which is precipitated by methyl alcohol, redissolved in chloroform, chlorinated, and then precipitated by methyl alcohol. The products obtained may be dissolved in chloroform, benzol, &c. They yield transparent, highly flexible films, and may also be used for the manufacture of moulded articles. varnishes, coatings, and artificial filaments; and they may be mixed with other cellulose esters which are soluble in the same solvents, such as cellulose acetate and nitrate, with or without plasticizers, and the solutions may be used for the manufacture of films. When the unsaturated esters are used for the manufacture of films, lavers of the unsaturated esters mav be combined with layers of the saturated esters, a common solvent being present to promote adhesion of the layers; thus, a film of the unsaturated ester may have a very thin film of hygroscopic cellulose acetate on the face opposite that which receives the photographic emulsion. The halogenated esters, particularly the bromo esters, show a proncunced resistance to burning, for instance, cellulose bromcinnamate is non-inflammable. Those esters in the manufacture of which the fibrous character of the initial material is retained, exhibit changed affinities towards dyestuffs, which affinities is further modified by the presence of halogen in the acyl group. This subject-matter does not appear in the Specification as accepted.