SU1073237A1 - Method of producing highly hydrophilic carboxy-methyl-cellulose - Google Patents

Abstract

WAY TO OBTAIN HIGH-. HYDROPHIL CARBOXIMBTHYL CELLULOSE, including mercerization of cellulose with an aqueous solution of caustic soda, from grinding of alkaline cellulose, carr bentomimethylation with monochloroacetic acid and heat treatment, o. t l ica y and so that, in order to simplify the process, the carboxymethylation is carried out at a molar ratio of cellulose, caustic soda and. monochloracetic acid 1: 2: 1.62, 0, and heat treatment at 50-80 C.

Description

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0: The invention relates to the production of cellulose ethers, in particular, high-hydrophilic cellulose carboxymethyl (CMC), capable of holding water, which is used for hygienic products (tampons, dressings, diapers), for dietary food, for improving the soil, for improving the film hydrophilicity. etc. A method is known for producing a high g of adrophilic CMC by a liquid process, in which the cellulose is dispersed in an inert organic diluent and is contacted in the first stage with a war of NaOH, and the resulting alkaline cellulose is reacted with an esternifying reagent, while the content of monochloroacetic acid (MHUC) and the body) is produced. alkali metal is selected and regulated so that molar, excess sodium chloroacetate with respect to unreacted NaOH exists, at a level that ensures the preparation of MaCMC with th substitution 0,4-1,2 ij. This method makes it possible to obtain CMC with a water retention index of 600-9000% and with a solubility of 9-40%. The disadvantage of this method is the necessity of using an organic solvent, which requires regeneration during the industrial implementation of the method, cross-linking agents and the need to carefully observe certain ratios of the reactants. A method of crosslinking cellulose derivatives without the use of crosslinking agents is also known, by intramolecular esterification. 2 However, this method requires an organic diluent and an acidic catalyst and preprocessing the polymer for introduction into non-hydroxyl and carboxyl groups. The closest to the proposed method is a highly hydrophilic, crosslinked CMC, consisting in mercerization with aqueous solutions of NaOH, KOH or LiOH from concentrations of 10-60% of natural cellulose or cellulose hydrate by immersion or disintegration laziness with potsleduyuschim squeezing excess alkali esterification MHUK or its salts and the simultaneous processing of a crosslinking agent at 95-108 ° C h. . . The disadvantage of this method is the need to use a crosslinking agent. The purpose of the invention is to simplify the process. This aim is achieved in that the process for producing highly hydrophilic CMC comprising mercerizing cellulose with an aqueous solution of caustic soda, shredding the alkali cellulose, carboxymethylation with monochloroacetic acid and heat treatment, carboxymethylation is carried out at a molar ratio of cellulose, sodium hydroxide and monochloroacetic acid 1: 2.2: 1,62, 0, and heat treatment - at 50-80 ° C. According to this method, the cellulose in the first stage is soaked with an aqueous solution of caustic soda with a concentration of 290 g / l and kept there for 1 hour at room temperature, then excess alkali is squeezed, the alkaline cellulose is ground and mixed at room temperature with the esterifying agent - MHUC for 1 After mixing, the reaction mass is subjected to heat treatment, in which, simultaneously with esterification, crosslinking of CMC occurs, after which it is washed with water or 70% ethyl alcohol. The concentration of the alkali solution 290 g / l in the subsequent degree of extraction of 2.8 provides the alkali content in alkaline cellulose in the amount of 2.2 mol per elementary unit of cellulose, which is necessary for the reaction of the carboxymethyoline to proceed. Amount of MCAA for esterification of 1.62 mol / cellulose elementary unit When using less than 1.6 mol, MCAA does not crosslink the polymer. With an increase above 2 moles of weight, caustic soda is consumed to neutralize MHUC and carboxymethylation does not occur. The heat treatment temperature, the duration of 3.5 hours. Increasing the temperature leads to uneven cross-linking of the polymer, and a decrease to a significant increase in the duration of the process. A duration of 3.5.h is determined by the chosen and justified temperature. Example 1. 50D g of wood pulp is soaked with an aqueous solution of caustic soda with a concentration of 290 g / l for 1 h at 18-20 s, then alkaline cellulose is squeezed from excess alkali to a degree of jog 2.8, then crushed for 1 h in the apparatus Werner Pfliderer, and then it is mixed with 541.7 (2.0 mol) MCAA 1 hour. After the completion of mixing, the reaction mixture is discharged into an oven and kept in it for 3.5 hours at 55 C. after which the polymer is washed water from the reaction byproducts and analyze. CMC has a water retention of 225 wt.% Undissolved residue 97%, degree of substitution 0.12.

Example 2. Analogously to example 1, 434 (1.6 mol MHUK is fed to mixing with alkaline cellulose only. The heat treatment mode is the same as in example 1. Rinsing of by-products in the reaction with 70% ethyl alcohol. Water retention of CMC-4610 weight. %, undissolved residue 61.5%, degree of substitution 0.35.

For example, p -3. Analogously to example 1, 488 g (1.8 mol) of MJUA are fed only for mixing with alkali cellulose. The heat treatment mode, as in example 1. Rinse with 70% ethyl alcohol.

The polymer has a water retention of 760 wt.%, The undissolved residue is 91.6%, the degree of substitution is 0.38.

Example (prototype). 500 g of wood pulp is treated with an aqueous solution of caustic soda concentration of 290 g / l and after an hour, excess alkali is extracted to a degree of extraction of 2.8. After grinding, the mass is mixed with 448 g (1.8 mol) of MCAA, 100 g of bicacrylamidoacetic acid and 50 g of dichloroacetic acid. After mixing, the esterification and cross-linking are carried out for

3.5 hours at. After washing

water and drying, the polymer has a water retention of 400 wt.%, an undissolved residue of 94% and a degree of substitution, 0.25, Example 5. Similarly to method 1, only the reaction mass is kept in an oven for 4 hours at 50 s. The polymer has a water retention of 230 wt.%, The undissolved residue, the degree of substitution is 0.14.

5 AND ROME er 6. Ana: logical to Example 1, only the reaction mass is kept in a drying oven for 1.5 hours at. The polymer has a water retention of 220 wt.%, The undissolved residue

0 95.7%, the degree of substitution is 0.15.

Comparative data on obtaining capable of swelling stitched CMC known and proposed methods are shown in the table.

From the table it can be seen that the proposed method makes it possible to obtain CMC; with a sufficiently wide interval of water retention; this eliminates the consumption of organic diluent and crosslinking agent. 50

Using the proposed method of obtaining high hydrophilic

CMC provides, in comparison with the well-known simplification of the method of obtaining, improvement of working conditions in the production of CMC, expansion. a range of medical products: prescriptions made using high hydrophilic CMC.

Claims (1)

(54 j METHOD FOR PRODUCING HYDRO-HYDROPHILIC CARBOXYMETHYL CELLULOSE, including mercerization of cellulose with an aqueous solution of sodium hydroxide, mashing alkaline cellulose, carboxymethylation with monochloracetic acid and heat treatment, which is intended to simplify the process , carboxymethylation is carried out at a molar ratio of cellulose, caustic soda and: monochloracetic acid 1: 2.2: 1, ^ 2.0, and heat treatment at 50-80 ° C.