Patent GB-528375-A (GB)
Title: Improvements relating to cellulose ester compositions
IPC: C08B3/16
Filed: 1939-01-16
Abstract: 528,375. Cellulose ester compositions. KODAK, Ltd. (Eastman Kodak, Co.). Jan. 16, 1939, Nos. 14168/40, 14169/40, 14170/40, 14171/40, 14172/40 and 14173/40. Divided out of 528,107. [Class 2 (ii)] Cellulose aceto-propionate or aceto-butyrate compositions are prepared with the aid of a liquid medium such that the compositions are clear liquids at a raised temperature above 50‹C. but form non-flowable self-supporting continuous clear gels at a temperature within the range of 10‹-50‹C. The constitution as regards acetyl and propionyl or butyryl content, of the cellulose mixed esters which may be used with specified solvents is shown graphically. In Fig. 1A, areas I, II, III, represent the constitution of various cellulose aceto-propionates or aceto-butyrates which may be dissolved at elevated temperatures by propylene chloride alone or propylene chloride and butylene chloride with or without ethylene chloride, or butylene chloride with ethylene chloride. The composition in per cent acetyl is indicated along the line AB and the per cent propionyl or butyryl is plotted along the line AC. The points ta, tp, tb, represent cellulose triacetate, tripropionate, and tributyrate respectively. Area I shows the constitution of cellulose aceto propionates or butyrates which give the desired gels on cooling solutions in ethylene chloride and propylene chloride. Area II shows the constitution of the mixed esters when using ethylene chloride and propylene chloride, or ethylene chloride and butylene chloride, or ethylene chloride, propylene chloride, and butylene chloride, or propylene chloride alone, or propylene chloride and butylene chloride. Area III is for ethylene chloride and butylene chloride, with or without propylene chloride, or propylene chloride and butylene chloride. Ethylene chloride where used should comprise less than half of the hot solvent mixture. In an example, cellulose aceto-propionate or butyrate of 10-18 per cent higher acyl content, containing at least 45 per cent total acyl is dissolved in a hot mixture of 60-95 per cent propylene chloride and 5-40 per cent ethylene chloride. The solutions may be used for forming transparent films. As shown in Fig. 1B, the cross-hatched area indicates the constitution of cellulose acetopropionates or aceto-butyrates which are to be used with mixtures of propylene chloride and alcohols such as ethyl alcohol, iso-propyl, n-propyl, n-butyl, sec-, ter-, or iso-butyl, or n-, iso-, sec-, or ter-amyl alcohol. These cellulose esters contain not more than about 35 per cent higher acyl and not less than about 39 per cent total acyl. In an example, a solution of 100 parts of a cellulose acetopropionate containing 30 per cent acetyl and 14.5 per cent propionyl content in 600 parts of a solvent mixture of 53 per cent of propylene chloride and 47 per cent of ter-amyl alcoholtogether with 10 per cent of triphenyl phosphate based on the weight of cellulose ester is prepared by stirring the ingredients at 60‹C. Suitable solvent mixtures of propylene chloride with various alcohols for cellulose esters of various higher acyl contents are shown graphically. As shown in Fig. 1C, the shaded area indicates the constitution of cellulose acetopropionates or aceto-butyrates which may be used with mixtures of trichloroethylene and ethylene chloride as hot solvent mixture. In the regions of lower content of propionyl or butyryl, solvent mixtures containing about 40-60 per cent of ethylene chloride should be used. For cellulose esters of higher content of propionyl or butyryl, the proportion of ethylene chloride in the solvent mixture should be reduced to 10-30 per cent. The cellulose aceto-propionates or aceto-butyrates used are those containing not less than about 12 per cent and not more than 39 per cent of higher acyl, and not less than 45 per cent total acyl content. As shown in Fig. 1D, the areas, I, II, indicate the constitution of cellulose acetopropionates or aceto-butyrates which give the desired gels with mixtures of trichlorethylene with mixtures of monohydric alcohols of not more than five carbon atoms. In the regions of lower content of propionyl or butyryl (Area I) it is preferable to use comparatively low boiling alcohols such as those of not more than three carbon atoms or the tertiary alcohols of four and five carbon atoms. Ethyl and methyl alcohols should be used to the extent of 10-30 per cent of the solvent mixture, and n- or iso-propyl alcohol, tertiary butyl and tertiary amyl alcohols should be used to the extent of 20-50 per cent of the solvent mixture. With cellulose esters of higher content of propionyl or butyryl (Area II) there should be used n- or iso-propyl, ter-butyl, or ter amyl alcohol to the extent of 40-60 per cent or any of the various butyl or amyl alcohols to the extent of 30-60 per cent of the solvent mixture. Fig. 1E indicates the constitution of cellulose aceto-propionates which may be used with mixtures of toluene and alcohols as hot solvent mixture. Fig. 2E indicates the constitution of cellulose-aceto-butyrates to be used with toluene-alcohol mixtures. For a cellulose aceto propionate of 23 per cent acetyl and 21 per cent propionyl content the toluene-alcohol mixture used may contain ethyl or isopropyl alcohol in quantities of 20-30 per cent of the solvent mixture. In place of toluene there may be used mixtures of toluene with benzene, xylene, or ligroin. With cellulose esters of higher propionyl or butyryl content xylene may be used instead of toluene. The cellulose aceto-propionates or aceto-butyrates used are those containing not less than about 18 per cent propionyl or 13 per cent butyryl, and not less than about 40 per cent total acyl. The third Provisional Specification also describes gel forming compositions of cellulose acetate.