RU2223278C1 - Method for preparing carboxymethylcellulose sodium salt - Google Patents

Abstract

FIELD: high-molecular compounds. SUBSTANCE: invention relates to preparing cellulose ether, namely, carboxymethylcellulose sodium salt that is used widely in petroleum-extracting and gas production, building, pharmaceutical, food and other branched of industry. Method is carried out by initial cellulose activation by hydropulping for 20-120 min at 30-40 C to form suspension in the concentration 0.1-2.5 wt.-% followed by condensing and squeezing out up to the liquid phase content 40-56 wt.-%. Prepared mass is stirred up. Then by cellulose dosing the latter is stirred partially with monochloroacetic acid sodium salt and prepared mixture and sodium hydroxide solution are fed to dual- screw machine with intense stirring for 1-2 min at the rate of reaction mass shift from 500 to 3 000 s^-1 and at temperature 65 C, not above, with simultaneous addition of high-molecular polyether based on ethylene oxide or propylene oxide as an aqueous solution in the concentration 25-50 wt.-%. Prepared product is dried in convective-contact regimen for 40-60 min at temperature 70 C, not above, followed by crushing. Invention provides the development of continuous manufacturing process with wasteless preparing method practically and high degree of ecology safety. The sequence of stages and regimens in carboxymethylation process allows widely using sort assortment of celluloses. EFFECT: improved preparing method. 2 tbl, 16 ex

Description

 The invention relates to the field of production of macromolecular compounds, namely, cellulose ether, sodium salt of carboxymethyl cellulose (hereinafter Na-CMC), which is widely used in oil and gas production, construction, pharmaceutical, food and other industries, and can be used to create continuous , a fundamentally new high-performance process for producing Na-CMC or to modernize existing industrial processes for the production of cellulose ethers.

 Modern problems in the field of chemical production put forward serious requirements for existing technologies: their versatility, environmental friendliness and commercial significance of the process. The development of a continuous, high-performance, virtually waste-free method using highly efficient equipment in combination with optimal process parameters allows us to solve the above problems and ensure the successful implementation of a technical idea.

A continuous method for producing Na-CMC is known, described in an article by I. M. Timokhin with collaborators "On the question of developing a continuous method for producing carboxymethyl cellulose" (publ. 1971), which allows the use of various types of celluloses. The method consists in processing cellulose in a continuous mercerization solution of sodium hydroxide solution with a concentration of 180-250 g / l at a temperature of 30-50 ^o With subsequent extraction to 2.6-3.2 times the weight, grinding and cooling the resulting alkaline cellulose, mixing it with the sodium salt of monochloracetic acid (hereinafter Na-MHUK) in a high-speed continuous mixer with the mass remaining in them for 1-2 minutes, keeping the resulting reactive mass in a screw or belt apparatus, granulation, drying in a pneumatic dryer in t chenie 2-5 minutes, the product further retained for 10-15 minutes and crushing the resulting Na-CMC. A feature of this method is that carboxymethylation is actually carried out in two stages: first, with high-intensity mixing with Na-MXYK and then the completion of carboxymethylation (the so-called ripening) occurs when combined with the drying stage. However, the modes in the known continuous method for producing Na-CMC do not provide the required quality of mixing the reagents, as a result of this, the properties of the resulting product are characterized by great heterogeneity, as well as low values of the degree of substitution for carboxymethyl groups and mass fractions of the basic substance, and, as a result, unsatisfactory stabilizing properties at using the resulting Na-CMC as a drilling fluid reagent.

 A new type of equipment is apparatuses that create high shear forces, the so-called reactor-mixing machines (hereinafter PCM), the working (technological) zones of which are formed by a set of forward and reverse turns. Passing through a series of consecutively located PCM working zones, the processed mixture is homogenized and acquires plasticity. The compressive and shear stresses arising in the material increase the intensity of the interaction of the reactants, create conditions for the splitting of cellulose into fibers, which increases the contact surface of the reactants. High shear forces of PCM provide mixing of the components in thin layers, which subsequently determines the uniformity of properties and, accordingly, the performance of the resulting product. In addition, the high mixing efficiency allows to obtain a reaction mass with uniformly distributed components very quickly, which significantly reduces the process and creates the prerequisites for the organization of production with high power. However, an indispensable condition for effective mixing in PCM is to ensure accurate dosage of the reagents. At the initial stage of using PCM to produce Na-CMC, powder cellulose was the only possible real raw material. The processing of cellulose in the form of bales, fibers with a low bulk density, sheets and the like within the framework of one technological process was impossible.

 A known method of producing Na-CMC, developed by Kharitonov S.V. etc., and published in the publication "Applied Aspects of Improving Chemical Technologies and Materials", which consists in the use of cotton cellulose molded into bales with a moisture content of not more than 10%, followed by loosening, preparation of alkaline cellulose in a continuous mixer with subsequent mixing in PCM -1, mixing alkaline cellulose with NaMXUK in PCM-2. To solve the problem of the necessary exact dosage, weighing batchers are introduced into the technological scheme, auxiliary cams are installed in the PCM screws to increase the mechanical impact on the product; to increase the residence time of the product in RSM-2, as well as to increase the degree of filling, the number of revolutions of the screw is underestimated. As a result of the implementation of this method received Na-CMC with a degree of polymerization of 800-900 with a high level of other characteristics. However, the achievement of a high degree of polymerization is ensured not so much by the advantages of the method as by the natural advantage of the processed raw materials — cotton pulp, which exists in the form of individual fibers and has a high initial degree of polymerization. In addition, this method, including multi-stage mixing using two PCMs, two paddle mixers, auxiliary cams for PCMs, provides for the mandatory stage of preparation of alkaline cellulose, which is technologically cumbersome, insufficiently effective and practically not applicable for processing other types of cellulose except cotton.

A known method of producing carboxymethyl cellulose (Na-CMC), protected by copyright certificate of the USSR 1063803, publ. in 1983. According to this method, the initial mixture of crushed cellulose and Na-MHUK simultaneously with a solution of sodium hydroxide (concentration of 21-26 wt.% in accordance with the examples) is fed to the PCM loading zone, from where it is transported to eight consecutive working areas of a twin-screw machine, where they maintain the specified temperature regime: first, the mixture is processed at a temperature of 20-25 ^° C, then it is increased to 85-100 ^° C until a plastic homogeneous state of the reaction mixture is reached; the residence time of the reaction mixture in PCM is from 3 to 6 minutes. The resulting product had a basic substance content of 50-70 wt.% With a degree of polymerization of at least 400 and a degree of substitution of 0.55-0.80, did not contain free alkali.

 The main disadvantage of this method of producing Na-CMC is that the Na-CMC obtained in accordance with this method has a low degree of polymerization and a degree of substitution that substantially impairs the performance of the product. The reasons that impede the achievement of the specified technical result include the fact that the conditions of the method in the absence of the stage of preparation of the cellulose structure before carboxymethylation lead to insufficient interaction of cellulose with Na-MCC. The inventors tried to solve this problem by multi-stage homogenization at high shear forces, however, these modes only led to an acceleration of the carboxymethylation reaction and its unevenness. This led to the rapid formation of a layer of swollen polymer on the surface of the reaction mass and the formation of Na-CMC in the form of lumps with a strongly swollen shell, impairing water solubility and uniformity of solutions.

The closest solution to the claimed is a method for producing carboxymethyl cellulose (Na-CMC), protected by copyright certificate of the USSR 1669917, publ. 1991 In accordance with the solution of the prototype, which aims to increase the efficiency of the carboxymethylation reaction and the stabilizing properties of the obtained Na-CMC in relation to drilling fluids, the cellulose is treated with an aqueous solution of sodium hydroxide and a carboxymethylating agent, the reagents are mixed in a twin-screw mixing reactor, having the number of working zones from 2 to 4, at a temperature of 20 to 30 ^o C and a residence time in working areas of 4 to 40 seconds.

 The prototype method has high efficiency due to the hardware solution of the process. However, the technological modes of the method, the absence of a stage of pretreatment of the cellulose structure cannot provide uniform carboxymethylation, which affects the performance of aqueous solutions of the obtained Na-CMC. In addition, the prototype method is limited in the choice of the type of pulp being processed, does not allow the pulp with low reactivity to be processed as part of a single technological process into a product with high performance indicators and is intended mainly for the processing of crushed pulp, which certainly reduces its technological significance. The lack of a developed accurate dosing system, contributing to the achievement of a technical result in processes using PCM, reduces, in particular, the effectiveness of the method.

 The invention consists in the following.

 The technical problem to which the claimed invention is directed was the creation of a continuous, highly environmentally friendly, virtually waste-free method for producing Na-CMC, development of the sequence of stages of this method, carboxymethylation modes (temperature, duration), the creation of special conditions that ultimately process a wide range of cellulose .

 The technical result of the claimed technical solution was to obtain Na-CMC, characterized by a uniform distribution of carboxymethyl groups, high degrees of substitution on various types of cellulosic raw materials, which determined properties such as high solubility in water and low rates of water loss in drilling fluid compositions.

The specified task in solving the prototype is carried out by preparing a homogenized reaction mixture from cellulose (cotton), Na-MHUK and an aqueous solution of sodium hydroxide in twin-screw PCM, while the formation of alkaline cellulose and carboxymethylation at a temperature of 20-30 ^o C with a residence time in working areas not more than 10 seconds.

The specified task in the claimed solution is carried out by pre-activation of cellulose by hydro-pulping with the formation of a suspension with a concentration of 0.1-2.5 wt. %, its subsequent thickening, extraction to a liquid phase content of 40-56 wt.%, loosening the squeezed pulp, followed by preliminary partial mixing with NaMXУK to obtain a reactive mass, feeding to PCM simultaneously with the supply of sodium hydroxide in the form of an aqueous solution with a concentration of 42 wt. % of a low molecular weight polyether based on ethylene oxide or propylene oxide in the form of an aqueous solution with a concentration of 25-50 wt.% at a given ratio of components, the formation of alkaline cellulose and the beginning of carboxymethylation I am in the process of mixing and homogenization, carried out for 1-2 minutes at shear rates of the reaction mass from 500 to 3000 s ^-1 , completion of carboxymethylation combined with drying, at a temperature of not more than 70 ^o C. Special cases of the implementation of the claimed invention, the appropriateness of which determine the type and brand of cellulose used, are the activation either in water or in an aqueous solution of sodium hydroxide concentration of 0.01-6.0 wt. % with the return of water or an aqueous solution of sodium hydroxide after adjusting the composition in the production cycle in a closed process loop. Another particular case of the invention, contributing to the achievement of the technical result, is the introduction into the process of a dosing system of the starting components, comprising dosing of cellulose by volume dosing of a suspension with a concentration of 0.1-2.5 wt.%; dosing of NaMXVK by weight dosing; dosing of aqueous solutions of sodium hydroxide with a concentration of 42 wt.% and low molecular weight polyether based on ethylene oxide or propylene oxide in the form of an aqueous solution before feeding to PCM by volume dosing.

 In the production of cellulose ethers, the first technological stage, as a rule, is the stage of preparing the cellulose structure for subsequent synthesis, which largely determines the completeness of the esterification and the properties of the resulting product. The effectiveness of the carboxymethylation reaction in the preparation of Na-CMC largely depends on the nature of the cellulosic feedstock and on its preliminary preparation. The nature of the pulp used determines the specifics of the preparation of raw materials. In the production of Na-CMC, celluloses that differ in the origin and method of cooking can be used: wood, viscose sulphite or sulphate, cotton cellulose, characterized by a high α-cellulose content, low hemicellulose content, as well as unbleached unbleached wood pulp containing lignin and other impurities. The origin and method of cooking various types of cellulose determines the complex of physicochemical properties of the feedstock used for carboxymethylation, the capillary-porous structure of the fiber, the density of the network of hydrogen bonds between macromolecules in amorphous regions, which ultimately determine their reactivity. In some cases, the pulp processing methods are dictated by the structural features and chemical composition of the original pulp. So, the high mass fraction of α-cellulose in cotton cellulose, the minimum amount of impurities significantly facilitate its processing. Processing more common and less expensive wood pulp (bleached and unbleached) is associated with great difficulties and requires a more complex process.

 For the practical use of Na-CMC, a number of indicators are important (solubility, viscosity, some other indicators, for example, the rate of water loss), which depend not only on the degree of polymerization and degree of substitution, but also on the uniformity of carboxymethylation. The uniform distribution of substituents during carboxymethylation is ensured, in particular, by a good preparation of the cellulose structure, which is characterized, inter alia, by swelling. A study of the reactivity of cellulose of various types and grades intended for carboxymethylation using PCM in a continuous process showed that cellulose swelling in this case should be sufficient, but not excessive.

 The introduction of the stage of activation of cellulose in the inventive method allowed to solve this problem. The development of the conditions for the stage of activation of cellulose, carried out by the method of hydro-pulping, set the task: to dissolve the cellulose and achieve its decomposition into individual fibers before the stage of carboxymethylation, i.e. loosen the physical structure of cellulose, cause it to swell, create a well-developed network of capillaries in the structure of cellulose, increase its inner surface, prepare it in such a way for fast and uniform sorption of reagents - sodium hydroxide and Na-MHUK, ensuring the uniformity and efficiency of the processes for producing alkaline cellulose and carboxymethylation. A feature of activation carried out in an aqueous solution of sodium hydroxide with a concentration of 0.1-6.0 wt.% Is that at this stage alkaline cellulose is not formed.

 The conditions for the implementation of the activation stage, the result of which is the formation of loose pulp in the form of a suspension with a concentration of 0.1-2.5 wt.%, Allow the activating agent to be evenly distributed inside the fibrous solid phase, which leads to high activation efficiency. The use of aqueous solutions of sodium hydroxide with a concentration of up to 6.0 wt. %, enhances the activation effect of certain types of wood pulp with low reactivity, and allows you to put hemicelluloses, fats and resins in a soluble state. Additional studies conducted by the applicant showed that exceeding the maximum value (over 6.0 wt.%) Of the hydroxide concentration in the aqueous solution used to activate cellulose can lead to: 1) undesirable cellulose degradation, which is actually associated with double alkaline treatment and corresponding structural changes (at the stage of activation and at the stage of formation of alkaline cellulose); 2) excessive cellulose swelling and technical difficulties during subsequent spinning to obtain squeezed cellulosic suspension with a given liquid phase content; 3) to excessive extraction and transfer to the working solution of hemicelluloses, resins and fats and, as a result, to an undesirable for continuous processes excess of the content of these substances in the circulating waters, hindering the operation of the equipment, leading to the so-called "tar difficulties".

 A feature of the proposed method is the return to the production cycle of waste water or sodium hydroxide solution in a closed technological circuit, which realizes the possibility of a continuous process and significantly improves its environmental performance. The adjustment of the composition used in the stage of activation of the aqueous sodium hydroxide solution is carried out by strengthening the calculated amount of the aqueous sodium hydroxide concentration of 42 wt.%.

 Premixing activated cellulose with NaMXYK allows NaMXYK to be evenly distributed in the pulp with the prepared structure, which contributes to the efficient and uniform subsequent carboxymethylation in the entire reaction mass, especially at its initial stage.

 The introduction of low molecular weight polyethers based on ethylene oxide and propylene oxide in the form of an aqueous solution into the reactive mixture promotes better homogenization of the mixture, improving the overall processability, preventing agglomeration (sticking of individual particles) of the formed Na-CMC, regulating the uniformity of carboxymethylation due to partial interaction with Na-MXУК . In addition, when mixing activated cellulose, Na-MXYK and an aqueous solution of sodium hydroxide at a concentration of 42 wt.% Under high shear conditions, the introduction of a low molecular weight polyester based on ethylene oxide or propylene oxide increases the rate of penetration of sodium hydroxide into cellulose, creating conditions for the priority of the reaction formation of alkaline cellulose and thus contributes to a more uniform and effective carboxymethylation. To implement the method, the corresponding polyesters with a molecular weight of from 300 to 600, sold under the brand name Laprol, for example Laprol 373 (TU 2226-017-10488057), Laprol 402 (TU) can be used as a viscous molecular polyether based on ethylene oxide or propylene oxide. 2226-013-10488057-94), Laprol ES-564 (TU 2226-019-10488-057-94), Laprol 502 M (TU 2226-012-05766801-93).

A study of the kinetics of carboxymethylation using twin-screw multi-zone PCMs showed that its most optimal mode is to create a temperature shock determined by the temperature at the outlet of the PCM, not exceeding 65 ^o C, in the regime of shear rates of the reaction mixture from 500 to 3000 s ^-1 within 1-2 minutes with the completion of carboxymethylation during drying in the convective-contact mode obtained Na-CMC at a temperature of not more than 75 ^o C.

 A feature of the proposed method, which helps to obtain a technical result, is to solve the problem of dosing the reagents: obtaining cellulose in the form of an aqueous suspension with a concentration of 0.1-2.5 wt.%, Using sodium hydroxide and a low molecular weight polyether based on ethylene oxide or propylene oxide in the form of water solutions allows for volumetric dosing very accurately; the Na-MHUK feed for preliminary mixing with activated cellulose is carried out by weight dosing using a microprocessor-controlled strain gauge system, which generally contributes to the achievement of a technical result.

 The method is as follows.

In the hydraulic pulper 1 with a working high-speed mixing device, pulp is fed; at the same time, depending on the type of cellulose used, water or an aqueous solution of sodium hydroxide with a concentration of 0.01-6.0 wt. % and carry out activation at a temperature of 30-40 ^o C for 25-40 minutes with the formation of a suspension with a concentration of 0.1-2.5 wt.%. Next, the resulting suspension by the mass pump 19 is transferred to a consumable container 2 equipped with a mixing device. From the drive, the suspension is continuously fed to the dispenser (in the particular case of implementation, to the volumetric dispenser) 3, from which the necessary amount of suspension enters the separator 4, in which it is concentrated 2.5-5 times, and the excess suspension is returned to the drive 2 ; water (aqueous sodium hydroxide solution) in the drive 5. The suspension is thickened to prepare it for subsequent extraction in the screw press 6 to a liquid phase content of 40-56 wt.%. The pulp is fed to the cultivator 7, where it is processed to the state of loose crumb. Then, through pneumatic transport, cellulose is fed through a cyclone 8 to a screw conveyor conveyor 9, equipped with a dispenser 9a, where Na-MHUK is fed: in a particular case, dosing of Na-MHUK is carried out by means of a weight batcher equipped with a microprocessor-controlled tensometric system. Partial mixing of the components with the formation of a reactive mixture is performed. At the same time, an aqueous solution of sodium hydroxide with a concentration of 42 wt.% Is prepared in the reactor 10, which is sent to the supply tank 11, and an aqueous solution of a low molecular weight polyether based on ethylene oxide or propylene oxide with a concentration of 25-50 wt. % in the reactor 12, which is sent to the supply tank 13. A reactive mixture consisting of activated cellulose and Na-MXУK, an aqueous solution of sodium hydroxide and an aqueous solution of low molecular weight polyester are separately fed into a twin-screw multi-zone PCM 14 equipped with a cooling jacket, where mixing and homogenization are carried out starting reagents. The operating parameters of this stage: the ratio of reagents, duration, temperature, shear rate, are determined by the type of cellulosic feedstock used. Next, the product enters the convection-contact dryer 15, where at a temperature of not more than 70 ^o C, provided by the air heater 16 and fan 20, carboxymethylation is completed, combining it with the drying of the obtained Na-CMC. After drying, the product is continuously fed through a closed pneumatic conveying line to the crushing units 17 and packaging 18.

 To implement the inventive method for producing Na-CMC can be used cellulose of the following types: short-fiber cotton cellulose, wood sulphite and wood sulphate cellulose; unbleached pulp. Cellulose is used as supplied, including in the form of sheets.

 Obtained in accordance with the claimed method, Na-CMC is a fibrous, fine-grained product having a high swelling rate in water; upon subsequent dissolution in water, particle aggregation was not observed.

 Assessment and evidence of the advantages of the proposed method are based on measuring the degree of substitution by carboxymethyl groups, mass fraction of the main substance, solubility, degree of polymerization and water loss in clay drilling mud compositions.

 The degree of substitution of the obtained Na-CMC was determined by precipitation of the copper salt of carboxymethyl cellulose at pH 4.0-4.1 and the subsequent iodometric determination of the amount of bound copper.

The degree of polymerization was determined by measuring the relative viscosity of a solution containing (2,000 ± 0.002) g Na-CMC in one cubic decimeter of sodium hydroxide solution with a molar concentration of 1.5 mol / dm ³ .

 In the examples below, a clay solution containing 1 wt.% Na-CMC was used to measure fluid loss. The water loss rate was determined as the volume of the filtrate, which was filtered for 30 minutes from a clay solution with a concentration of 7 wt.% Saturated with sodium chloride through a paper filter on a filter press.

 A specific implementation of the claimed invention is illustrated by the following examples.

 Examples 1-3.

 For processing used wood sulfate unbleached rayon viscose pulp with a degree of polymerization of 1700 (GOST 24299-80). The characteristics of the types and grades used in these and subsequent examples of pulp are shown in table 1.

 Activation was carried out for 120 min in an aqueous solution of sodium hydroxide with a concentration of respectively 0.8 wt.% (Example 1), 3.0 wt.% (Example 2), 6.0 wt. % (example 3), after extraction, the content of the liquid phase in the cellulose was respectively 40 wt.% (example 1), 50 wt.% (example 2), 56 wt.% (example 3).

 In accordance with the above method, the preparation of Na-CMC was carried out at the following process parameters.

 The ratio of components, parts by weight: cellulose absolutely dry 100; sodium hydroxide in terms of absolutely dry substance 39.5 (1); 42 (2); 44.4 (3); Na-MXYK 101 (1); 108 (2); 115.1 (3); water 124.5 (1); 161.1 (2); 192.4 (3); simple low molecular weight polyester based on ethylene oxide of molecular weight 400 Laprol 402 0.6 (1); 1.8 (2); 3.0 (3).

 The duration of carboxymethylation in a twin-screw four-zone PCM is 1.0 minute (1); 1.5 minutes (2); 2.0 minutes (3).

Shear rate in PCM 500 s ^-1 (1); 1000 s ^-1 (2); 3000 s ^-1 (3).

The temperature in the PCM is 40 ^o C (1); 50 ^o C (2); 65 ^o C (3).

Drying temperature 70 ^o C (1); 60 ^o C (2); 55 ^o C (3).

 Drying time 40 minutes (1); 50 minutes (2); 60 minutes (3).

 Example 4 (comparative in accordance with the prototype).

In accordance with the decision of the prototype method was carried out as follows. 100 parts by weight were fed into the twin-screw four-zone PCM. sulfate unbleached viscose pulp with a degree of polymerization of 1700 (GOST 24299-80), 100 parts by weight NaMXUK and 42 parts by weight an aqueous solution of sodium hydroxide (in terms of absolutely dry cellulose), intensive stirring was carried out for 6 seconds at a temperature of 20 ^o C, after which the reaction mass was dried at a temperature of 80 ^o C for 120 minutes.

 The test data obtained Na-CMC are shown in table 1.

 Examples 5-7.

 For processing used bleached viscose rayon pulp with a degree of polymerization of 1200 (GOST 24299-80).

 Activation was carried out for 60 minutes in an aqueous solution of sodium hydroxide with a concentration of 0.2 wt.% (Example 5), 1.0 wt.% (Example 6), 2.0 wt. % (example 7); after extraction, the content of the liquid phase in the cellulose was respectively 40 wt.% (example 5), 50 wt.% (example 6), 56 wt.% (example 7).

 In accordance with the above method, the preparation of Na-CMC was carried out at the following process parameters.

 The ratio of components, parts by weight: cellulose absolutely dry 100; sodium hydroxide in terms of absolutely dry substance 39.5 (5); 42 (6); 44.4 (7); Na-MXYK 101 (5); 108 (6); 115.1 (7); water 124.5 (5); 161.1 (6); 192.4 (7); a simple low molecular weight polyester based on propylene oxide of molecular weight 370 Laprol 373 0.6 (5); 1.8 (6); 3.0 (7).

 The duration of carboxymethylation in PCM is 1.0 minute (5), 1.5 minutes (6), 2.0 minutes (7).

The shear rate in PCM is 500 s ^-1 (5); 1000 s ^-1 (6); 3000 s ^-1 (7).

The temperature in the PCM is 40 ^o C (5); 50 ^o C (6); 65 ^o C (7).

Drying temperature 50 ^o C (5); 60 ^o C (6); 70 ^o C (7).

 Drying time 60 minutes (5), 50 minutes (6), 40 minutes (7).

 Example 8 (comparative in accordance with the prototype).

In accordance with the decision of the prototype method was carried out as follows. In the twin-screw three-zone PCM filed 100 wt. including sulfate bleached viscose rayon pulp with a degree of polymerization of 1700 (GOST 24299-80), 100 wt. including Na-MXUK and 42 parts by weight an aqueous solution of sodium hydroxide (in terms of absolutely dry cellulose), intensive stirring was carried out for 10 seconds, after which the reaction mass was dried at 80 ^o C and for 120 minutes.

 Examples 9-11.

 For processing, we used sulfite bleached viscose rayon cellulose with a degree of polymerization of 1000 (TU 5411-027-00279163-95).

 Activation was carried out for 30 minutes in an aqueous solution of sodium hydroxide with a concentration of 0.2 wt.% (Example 9), 0.4 wt.% (Example 10), 0.6 wt.% (Example 11); after extraction, the content of the liquid phase in the cellulose was respectively 40 wt.% (example 9), 50 wt.% (example 10), 56 wt. % (example 11).

 In accordance with the above method, the preparation of Na-CMC was carried out at the following process parameters.

 The ratio of components, wt. including: cellulose absolutely dry 100; sodium hydroxide in terms of absolutely dry substance 39.5 (9); 42 (10); 44.4 (11); Na-MHUK 101 (9); 108 (10); 115.1 (11); water 124.5 (9); 161.1 (10); 192.4 (11); simple low molecular weight polyester based on propylene oxide of molecular weight 560 Laprol ES-564 0.6 (9); 1.8 (10); 3.0 (11).

 The duration of intensive mixing in a twin-screw dual-zone PCM is 1.0 minute (9), 1.5 minutes (10), 2.0 minutes (11).

The shear rate in PCM is 500 s ^-1 (9), 1000 s ^-1 (10), 3000 s ^-1 (11).

The temperature in the PCM is 40 ^o С (9), 50 ^o С (10), 65 ^o С (11).

The drying temperature is 50 ^o C (9), 60 ^o C (10), 70 ^o C (11).

 The drying time is 60 minutes (9), 50 minutes (10), 40 minutes (11).

 Example 12 (comparative in accordance with the prototype).

In accordance with the decision of the prototype method was carried out as follows. In the twin-screw three-zone PCM filed 100 wt. including sulfite bleached viscose rayon pulp with a degree of polymerization of 1000 (TU 5411-027-00279163-95), 100 wt. including NaMXUK and 42 parts by weight an aqueous solution of sodium hydroxide (in terms of absolutely dry cellulose), intensive stirring was carried out for 20 seconds, after which the reaction mass was dried at 80 ^o C and for 120 minutes.

 Examples 13-15.

 Cotton pulp with a polymerization degree of 2400 (GOST 595-79) was used for processing.

 Activation was carried out for 20 minutes in water: after extraction, the content of the liquid phase in the cellulose was respectively 40 wt.% (Example 13), 50 wt.% (Example 14), 56 wt.% (Example 15).

 In accordance with the above method, the preparation of Na-CMC was carried out at the following process parameters.

 The ratio of components, parts by weight: cellulose absolutely dry 100; sodium hydroxide in terms of absolutely dry substance 39.5 (13); 42 (14); 44.4 (15); Na-MXYK 101 (13); 108 (14); 115.1 (15); water 24.5 (13); 161.1 (14); 192.4 (15); simple low molecular weight polyester of propylene oxide of molecular weight 525 Laprol 502-M 0.6 (13); 1.8 (14); 3.0 (15).

 The duration of intensive mixing in a twin-screw dual-zone PCM is 1.0 minute (13), 1.5 minutes (14), 2.0 minutes (15).

The shear rate in PCM is 500 s ^-1 (13), 1000 s ^-1 (14), 3000 s ^-1 (15).

The drying temperature is 50 ^° C (13), 60 ^° C (14), 70 ^° C (15).

 Drying time: 60 minutes (13), 50 minutes (14), 40 minutes (15).

 Example 16 (comparative).

 Cotton pulp with a polymerization degree of 2400 (GOST 595-79) was used for processing.

In accordance with the decision of the prototype method was carried out as follows. 100 parts by weight were fed into a twin-screw three-zone PCM. cotton cellulose with a degree of polymerization of 2400 (GOST 595-79), 100 parts by weight Na-MXУK and 42 parts by weight an aqueous solution of sodium hydroxide (in terms of absolutely dry cellulose), intensive stirring was carried out for 10 seconds, after which the reaction mass was dried at 80 ^o C and for 120 minutes.

Claims (8)

1. The method of obtaining the sodium salt of carboxymethyl cellulose by metering cellulose, an aqueous solution of sodium hydroxide and sodium salt of monochloracetic acid, feeding them into a twin-screw multi-zone reactor-mixing machine, intensive mixing, followed by drying and crushing, characterized in that the cellulose is initially activated by hydro-pulping for 20-120 min at 30-40 ° С with the formation of a suspension with a concentration of 0.1-2.5 wt.%, followed by thickening and pressing to a liquid phase content of 40-56 wt.%, gender the studied pulp mass is loosened, it is preliminarily partially mixed with the sodium salt of monochloracetic acid when the mixture is obtained and an aqueous solution of sodium hydroxide is fed into a twin-screw multi-zone reactor-mixing machine, while a simple low molecular weight polyester based on ethylene oxide or propylene oxide is introduced in the form of an aqueous solution of propylene in the form of an aqueous solution 25-50 wt.%, intensive stirring is carried out for 1-2 minutes at the reaction mass shear rates from 500 to 3000 s ^-1 and a temperature e more than 65 ° C, and drying the resulting product is carried out in a convection-contact mode for 40-60 minutes at a temperature not exceeding 70 ° C. 2. The method according to claim 1, characterized in that the pulp hydro-pulping is carried out in water. 3. The method according to claim 1, characterized in that the pulp hydro-pulping is carried out in an aqueous solution of sodium hydroxide with a concentration of 0.01-6.0 wt.%. 4. The method according to PP.1 and 2, characterized in that after the implementation of hydro-pulping water is returned to the production cycle in a closed process loop. 5. The method according to claims 1 and 3, characterized in that after hydropulping and adjusting the composition, the aqueous sodium hydroxide solution is returned to the production cycle in a closed process loop. 6. The method according to claim 1, characterized in that the dosing of cellulose is carried out by volumetric dosing of a suspension with a concentration of 0.1-2.5 wt.%. 7. The method according to claim 1, characterized in that the dosing of the sodium salt of monochloracetic acid is carried out by weight dosing. 8. The method according to claim 1, characterized in that the dosing of sodium hydroxide and low molecular weight polyester based on ethylene oxide is carried out by volume dosing.

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