METHYLCELLULOSE-BASE COMPOSITION AND METHOD FOR ITS PREPARING Russian patent published in 2003 - IPC

FIELD: chemical technology. SUBSTANCE: invention relates to method for preparing compositions based on cellulose ether, i. e. methylcellulose. Composition contains 0.3-0.5 wt.- % of bound glyoxal and mixture of alkaline metal salts including sodium dihydrogen phosphate and sodium hydrogen phosphate taken in the mole ratio to sodium dihydrogen phosphate = (1.35-3.00):1 in the following ratio of components, mas. p. p.: methylcellulose, 100; indicated mixture of salts, 2.5-3.0. Method involves preparing alkaline cellulose and its methylation. After methylation the prepared reaction mass is suspended in an aqueous medium containing glyoxal and ortho-phoaphoric acid and cross-linkage with glyoxal is carried out adding in the amount 0.05-0.20 mole per anhydroglucose cellulose link in an aqueous medium containing ortho-phosphoric acid. Washing out is carried out at hydromodulus = (5- 10):1 and temperature 30-60 C for 30-60 min and phosphoric acid is added in the amount providing pH value from 2.2 to 3.5. Then washing out is carried out with an aqueous solution of mixture of salts containing sodium dihydrogen phosphate and sodium hydrogen phosphate taken in the mole ratio = 1.00:(1.35-3.00), in the concentration of indicated salts mixture in solution 4-7% and temperature 80-95 C being before drying the prepared composition is squeezed out. Invention provides increasing dissolving rate of composition in cold water and to retain the polymerization degree of methylcellulose. Viscosity of the composition aqueous solutions remains at level of viscosity of aqueous solutions of methylcellulose without cross-linkage with glyoxal. Invention provides reducing loss of composition in the process preparing at washing out stage. Compositions can be used as emulsifying agents, thickening agents, dispersing and stabilizing agents, in building, chemical, oil and gas production industry. EFFECT: improved preparing method, valuable properties of compositions. 1 tbl, 8 ex