DD207380A1 - PROCESS FOR PREPARING HIGH-SOURCE CARBOXYMETHYL CELLULOSE - Google Patents

Abstract

The invention includes a process for the preparation of high-swelling carboxymethylcellulose by homogeneous reaction of in molten N-methylmorpholine N-oxide geloester cellulose with monochloroacetic acid or the Na salt of Monochloressigsauere in the presence of sodium hydroxide solution, wherein the production still occurs during the post-treatment, crosslinking of the products. The products produced by this process can be used in pharmacy, biology, medicine, eg. B. as a sorbent and in the chem. Industry, z. B. for the adsorption of dispersed water from water or limited miscible liquids are applied.

Description

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Dr. Brigitte Lukanoff Teltow, 21.10.1982

Title of the invention

Process for the preparation of high swelling carboxymethyl cellulose

Field of application of the invention

The invention relates to a process for the preparation of bochquellender Carboxymetbylcellulosen. The products produced by this process can be used in many ways in pharmacy, biology and medicine, e.g. B. be used as a sorbent "In the chemical industry, the Carboxymetbylcellulosen z. B. for the adsorption of dispersed water from water or limited miscible liquids are used.

Characterization of the known technical solutions

According to the prior art, the preparation of carboxymethylcellulose (CMC) proceeds via a heterogeneous Williamson ¹ -ethersyntbese synthesis by reaction of cellulose in an aqueous alkaline medium with monochloroacetic acid, the reaction medium noob. an inert solvent, such as. B * - Isopropanol can be added.

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Depending on the reaction conditions, carboxymethylcelluloses which are soluble in water with DS > 0.2 and soluble in DS> 0.5 are obtained. The products produced in this manner with DS > 0.01 to 0.4 show no appreciably high swelling capacity in water ,

The production of carboxymethylcellulose with high swelling capacity, d _e h. with high water retention capacity (WRV) is described in numerous patents.

In this case, the procedure is predominantly carboxymethylated up to a DS, which leads to water solubility, carboxymethyl cellulose, in order subsequently to crosslink this product to a water solubility lying in the range from 0 to 50 % . This crosslinking reaction can be carried out before, during and after the etherification. Epicblorbydrin (DE-OS 1 912 740), acrylamido compounds and other bifunctional substances can be used as crosslinking agents for CMC (DE-OS 2 357 079). The disadvantage of these methods is that the high swelling ability of this CMC is only possible by crosslinking reactions, which requires the use of crosslinking agents, which are often expensive and more or less toxic. Due to the additionally inserted foreign crosslinker bridges, new toxicological test methods may prove necessary for certain applications of the CMC.

German Offenlegungsschrift 2,151,973 describes a process for the production of CMC after the slurry process, in which process is carried out in a water-miscible organic diluent. In this case, cross-linking occurs by the etherification agent itself. Provided that a large equimolar excess of sodium monochloroacetate, based on sodium hydroxide and anhydroglucose unit, is used in the system * so that a weakly acidic product forms in the crosslinking phase. These products have WRV between 1000 to 7000 and a good whiteness (Jayme, G., Büttel, H .: Wochenblatt für Papierfabr., 96 (1968) 180).

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By way of limitation, it has to be said that this method requires a relatively high use of expensive monocbloroacetic acid at low yield and that products with a high salt content are obtained. The preparation of crosslinked CMC without addition of crosslinking agents is described in US Pat. No. 3,733,413, in the presence of some of the by-products, in US Pat. No. 3,731,686, defined acidification in alcoholic suspension and in US Pat. No. 2,920,019 after treatment described with dry HCl gas ·

These methods have in common that the CMC must always be dried and that for crosslinking temperatures greater than TOO ⁰ C, preferably 130 to 210 ⁰ C, must be required. A reproducible process management is quite difficult. The WRVs of the crosslinked CMC are smaller than those generated by additional crosslinking agents.

The aim of the e _r-making

The object of the present invention is a process for the preparation of high-swelling carboxymethylcellulose, which overcomes the drawbacks and deficiencies of known processes by the production of bochquellender carboxymethylcellulose in a reaction stage without the addition of a crosslinking agent or an annealing process and physiologically acceptable products are obtained with high performance properties.

Explanation of the essence of the invention

- Task

The object of the invention is to produce high-swelling carboxymethylcellulose by homogeneous conversion of cellulose dissolved in molten N-methylmorpholine N-oxide with monochloroacetic acid or with the Na salt of monochloroacetic acid with addition of sodium hydroxide solution.

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a uniform DS distribution is guaranteed.

Features of the invention

Surprisingly, it has been found that carboxymethylation of cellulose dissolved in molten N-methylmorpholine N-oxide (MMNO) with monochloroacetic acid or the Na salt of monochloroacetic acid takes place in the presence of sodium hydroxide solution.

This procedure is such that cellulose, such as. B. pulps, linters at 85 ⁰ C in molten MMNO is dissolved and the Celluloselö'ssung dissolved in sodium hydroxide Na salt of monochloroacetic acid (Na-MCE) or dissolved in isopropanol monochloroacetic acid (MCE) is added with the addition of sodium hydroxide solution

 In the case of Na-MCE, the concentration of the caustic soda was

5 to 24 % i wherein the molar ratio of cellulose: NaMCE: NaOH must be at least 1.0: 0.2: 0.2. In order to ensure a higher utilization of the Na-MCE reagent, a certain excess of NaOH should be used.

When using MCE as Carboxymethylierungsmittel this was first in an organic diluent, such. The concentration of the sodium hydroxide solution is between 5 and 30%, whereby the molar ratio of cellulose % MCE: NaOH must be at least 1.0 % 0.2: 0.4 and also beer For a better reagent yield of MCE, a certain excess of NaOH is necessary

The weight ratio MMNO % isopropanol should not be larger

Be 6: 1.

The reaction temperature may be 65 to 110 ⁰ C, preferably 85 ⁰ C, the reaction time 30 to 150 min and the cellulose concentration up to 15%. Instead of the basic component added as sodium hydroxide can also be amines such. As N-methylmorpholine or methylamine can be used. The carboxymethylation proceeds homogeneously over the entire reaction time, so that the resulting carboxymethylcellulose remains dissolved in this cellulose solvent.

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The reaction is stopped by pouring the reaction solution into an alcohol-water mixture. The CMC samples obtained as a flake are washed salt-free with an alcohol-water mixture and dried.

Depending on the reaction conditions, d. Jb. From the MoI ratio MCE or Na-MCE; Cellulose, from the reaction time and the reaction temperature, it is possible to produce both high-swelling water-soluble and water-insoluble carboxymethyl cellulose. The bump-swelling carboxymethyl celluloses in the DS range of 0.05 to 0.35 have a water-repellency of between 1,000 and 10,000. ^ ';. · · ... "':',". ' , · · ''. ' ''

The invention will be explained with reference to the following embodiments:

Ausfübrungsbeispiele

1. In 120 g of molten N-methylmorpholine N-oxide 6 g of spruce sulphite pulp are dissolved at 85 ⁰ C. Thereafter, an addition of 3.6 g in 20 ml of isopropanol dissolved monochloroacetic acid and 30 ml 1Obiger sodium hydroxide solution. After 120 min and a reaction temperature of 85 ⁰ C, the carboxymethyl cellulose was precipitated by pouring the reaction solution into an alcohol-water mixture 50:50, washed salt-free and dried.

DS «0.20 WRV = 9350

2. In 60 g at 85 ⁰ C molten N-methylmorpholine N-oxide 3 g Pichten-sulf it pulp-dissolved and then with 1.35 g in 10 ml of isopropanol dissolved monochloroacetic acid and 3.75 ml of 24% NaOH at 85 ⁰ C 240 min carboxymethylated.

The carboxymethylcellulose obtained after precipitation in an alcohol-water mixture followed by washing and drying has a DS = 0.06 and a WRV 1225.

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3. 4 g of cellulose are dissolved in 120 g at 85 ⁰ C molten N-methylmorpholine N-oxide and after, then adding 2.7 g in 10 ml of 10 % sodium hydroxide solution dissolved Na salt of monocbloroacetic acid (Na-MCE) at 85 ⁰ Q carbqxymethyliert. After 120 min, the reaction is stopped by pouring the reaction solution into an alcohol-water mixture, (50:50) and after. Washing and drying of carboxymethylcellulose has DS s 0.11 and WRV = 1450.

4. 5 g Pichtensulfitzellstoff be dissolved in 120 g at 85 ⁰ C molten N-Metbylmorpholin-N-oxide and carboxymethylated after addition of 2.7 g in 12 g of methylamine dissolved Sa salt of MonoChloressigsäure at 85 ⁰ C. The termination of the reaction is carried out by. Pour the reaction solution into an alcohol-water mixture 20:80. The product obtained after washing and drying has a DSV 0.08 and a WRV * 1050.

Claims (2)

2444.77: .6 claim for invention 1. A process for the preparation of hydrogenating cumoxymethylcellulose in the presence of aminoxide-containing solvents, characterized in that the dissolved cellulose with monochloroacetic acid or the Ba salt of monochloroacetic acid at temperatures of 65 to 110 ⁰ C, preferably 85 ⁰ C, a reaction time of 30 to 150 min and the cellulose concentration is carboxymethylated up to 15 % in homogeneous phase to a DS of 0.05 to 0.35. 2. The method according to item 1, characterized in that the reaction of the cellulose with ifonochloroacetic acid both in the presence of sodium hydroxide solution of the concentration of 5 to 30% and a molar ratio of cellulose: MCE: NaOH of at least 1.0: 0.2: 0.2 and / or in the presence of amines in the concentration of 5 to 20 %, preferably 10% kanüa