WO2016072885A2

WO2016072885A2 - Cellulose production method

Info

Publication number: WO2016072885A2
Application number: PCT/RU2015/000869
Authority: WO
Inventors: Яков Кузьмич АБРАМОВ; Владимир Михайлович ВЕСЕЛОВ; Виктор Михайлович ЗАЛЕВСКИЙ; Виталий Григорьевич ТАМУРКА; Вениамин Сергеевич ВОЛОДИН; Владимир Дмитриевич ЕВДОКИМОВ; Борис Иванович МИРОНОВ; Ольга Борисовна ВАТУЕВА; Николай Александрович ГУКАСОВ; Людмила Михайловна МАРШАННИКОВА; Татьяна Михайловна МОРДВИНОВА; Наталья Александровна САЛОМАТИНА; Дмитрий Константинович САРЫЧЕВ; Александр Иванович ПИЛЬГУН; Валентина Ивановна БИРЮКОВА
Original assignee: Общество с ограниченной ответственностью "Твин Технолоджи Компани"
Priority date: 2014-11-05
Filing date: 2015-12-11
Publication date: 2016-05-12
Also published as: KR20180083251A; EP3216917A2; EP3216917A4; WO2016072885A3; JP2017535690A

Abstract

The invention relates to the chemical industry, and more particularly to a method for producing cellulose from different cellulosic raw materials for the paper and textile industries and other branches of industry, including for gunpowder technologies. The present method consists in soaking and hydrolysing a raw material in an environment of a hydrolysis solution, filtering cellulose, rinsing with water, filtering, and drying, accompanied by the implementation of cycles that include heating the material to a temperature of 115°C or less, and rapid vacuum pulse action with a change of pressure in a range of up to 5 mmHg for a period of less than 10 seconds, and subsequently holding in a vacuum and releasing the vacuum. The proposed method is universal. A solution of nitric or sulphuric acid, or a combination thereof, or an alkaline solution can be used as the hydrolysis solution. A solution of spent acids from nitrocellulose production can be used, thus reducing costs. The technical result of the claimed method consists in the production of cellulose of the required grade from any cellulosic raw material, a significant reduction in the length of the cellulose hydrolysis process, and a reduction in the temperature of the processes for producing the required chemical and structural uniformity of cellulose, without the need for special equipment. The method makes it possible to favour hydrolysis using acidic solutions, thus simplifying the composition of the hydrolysis solution.

Description

METHOD FOR PRODUCING CELLULOSE

The invention relates to the chemical industry, namely to the production of cellulose from all types of plant cellulose-containing material, chemically and structurally homogeneous, bleached and unbleached, for paper, textile, medical, nitrocellulose (hereinafter - SC) industry, paint and varnish, powder technology, which can be used for further processing in various industries: SC for gunpowders, varnishes, enamels, textile, paper, medical, pharmaceutical, food, etc. As a price lulose-containing raw materials use coniferous and deciduous wood, cotton, flax, hemp, fruit shells of cereal crops (oats, etc.), straw of cereal crops, as well as bamboo, miscanthus, amaranth, bagas, export, etc.

There are many methods for producing celluloses from wood and annual plants, and their number continues to grow. All methods for producing cellulose are based on the fact that lignin, hemicellulose, and other impurities give in to the destructive action of chemicals and technological parameters much more easily than cellulose.

The most common method for producing various pulps is currently the sulfate method. In the world pulp and paper industry, this method produces up to 90-95% of all types of pulp. The sulphate pulp production method belongs to the group of alkaline methods. With the sulfate method, the process is carried out batchwise at 160-180 ° C, with pH = 13, a pressure of 0.7-1.5 MPa for 4-6 hours, with continuous cooking at a temperature of 190-200 ° C, the process takes about 30 minutes . The use of high (up to 1.5 MPa) pressure for large reactor boilers (up to 400 m ³ or more) with high temperatures complicates the process and its hardware design. Despite the use of high temperatures, the lignin separation process at 145 ° C takes place in 12 hours, at 160-180 ° C in 4-6 hours, and only at 200 ° C for 30 minutes. The introduction of additional components into the reagent causes the emission of gases that worsen the ecology of the air basin, complicates the regeneration of solutions and washing of cellulose with the use of a large amount of water and complicating the organization of their circulation.

Sulfite belongs to the group of acidic methods for producing celluloses, inorganic (HNO ₃ , НС1), organic (acetic, monochloroacetic and other) acids, as well as ethylene glycol, phenol, butyl and other alcohols, as well as a calcium base, are used as reagents containing Ca (HS0 ₃ ) ₂ with an excess of S0 ₂ , supporting the pH of the solution at a level of 1.2-1.5. Gaseous S0 ₂ having strongly acidic properties, penetrates into wood chips faster than the solution, therefore, the heating of the solution is slower, otherwise incomplete delignification of wood occurs. The temperature of the solution in the manufacture of paper pulp lies in the range 125-135 ° C, and pulp for the chemical industry 145 ° C, the duration of the process is up to 12 hours. The application of this method leads to a deterioration in the sorption properties of the obtained cellulose, its structural and chemical heterogeneity, a reduced degree of crystallinity, and a decreased stability of properties during storage.

In both methods, the cellulose obtained, especially when obtained by the sulfate method, cellulose is molecularly heterogeneous. The output characteristics of celluloses have increased scatter in viscosity, α-cellulose content, etc.

To obtain better pulp, combined methods are used with the addition of soda, chlor-alkali, etc., which significantly complicate the production.

A known method of producing fibrous cellulose from cellulose-containing raw materials using an aqueous solution of nitric acid as a delignifying agent (RF patent N ° 2353626, IPC С08В1 / 04; D01F2 / 00, dated October 25, 2007). In addition to nitric acid, the treatment solution contains surfactants, an ammonium inorganic salt or potassium or sodium nitrate. The oxidative treatment is carried out in an alkaline peroxide solution containing sodium carboxymethyl cellulose and a nonionic water-soluble cellulose ether.

The disadvantages of this method are the use of a large number of reagents and a number of additives, including surfactants that are difficult to utilize, and also provides for the introduction of carboxymethyl cellulose, which complicates the process, leads to its cost increase, the method requires a large flow of water for washing the cellulose.

A known method of producing cellulose by cooking wood chips from hardwood in sulphite cooking solution and subsequent washing (RF patent N ° 2010069, IPC D21C3 / 06 from 08.07.1992). A mixture of crude tower sulfite acid with a Na ₂ 0 content of 1.45-1.65% and a total of S0 ₂ 4.2-4.8% and an aqueous solution of sodium carbonate with a concentration of 90-110 g / l at their volume the ratio is from 100: 3 to 100: 5, and cooking is carried out when the content in the cooking solution of bound S0 ₂ 1.75-2.25% and Na ₂ 0 1.65-2.18% and pH 2.5-4.0 . Cooking is carried out at a concentration of only S0 ₂ 3.8-4.5%.

This method is used to obtain cellulose from wood chips from hardwood or from low-resinous species of wood: spruce, fir. The disadvantage of this method is the use of reagents that degrade the ecological environment of air and water pools. The resulting cellulose does not have sufficient chemical and structural homogeneity.

The production of wood pulp is considered a capital-intensive industry using large-sized equipment and the consumption of a huge amount of water.

A known method of producing cellulose from non-wood plant materials with a content of native cellulose of not more than 50% and an aqueous solution of caustic soda (RF patent No. 2448118, IPC С08В 11/12, 1/00, 1/02, dated 09.11.2010). The raw materials are washed with hot water at a temperature of 40-75 ° C at atmospheric pressure for 0.5-4.0 hours, delignification is carried out at a temperature of 90-95 ° C with an aqueous solution of nitric acid at a concentration of 2-8% for 4-20 hours. Next, the cellulose is subjected to additional processing with a solution of caustic soda 1-4% at a temperature of 60-95 ° C for 1-6 hours, which increases the duration of the process. This stage reduces the degree of polymerization and leads to a deterioration in the quality of cellulose, in particular, to a decrease in the strength index.

As a prototype of the selected method of processing cellulose-containing raw materials

(RF patent JYs2456394 IPC D21C 1/02, 3/02, 9/10, 9/16, 1 1/04; C07G 1/00, dated 08/08/2010), where the processing of cellulose-containing raw materials is carried out by the following stages of the process: prehydrolysis (impregnation), boiling (hydrolysis) of lignocellulose in 30% hydrotropic solution for 1-3 hours, filtering the resulting cellulose, washing it with 30% hydrotropic solution, subsequent washing with water, bleaching the pulp with hydrogen peroxide in sodium hydroxide solution to obtain bleached cellulose, treatment with an acid solution followed by treatment with a solvent m, filtration and drying. As cellulose-containing raw materials, miscanthus or fruit shells of cereal crops, or straw of cereal crops are used.

In this method, miscanthus or fruit shells of cereal crops, or straw of cereal crops are used to obtain cellulose, however, the resulting cellulose does not have sufficient chemical and structural homogeneity.

The output characteristics of the cellulose obtained by the considered methods have increased scatter in viscosity, alpha-cellulose content and other indicators.

The aim of the invention is to provide a method for producing cellulose of high quality, with chemical and structural homogeneity from various cellulose-containing raw materials, while simplifying and cheapening the process.

The goal is achieved by processing cellulose-containing raw materials, including the impregnation and hydrolysis of the raw materials in a hydrolysis solution, filtering the resulting cellulose, subsequent washing with water, filtering and drying, in which, according to the invention, the impregnation and hydrolysis of raw materials in a hydrolysis solution medium, filtering the resulting cellulose, subsequent washing with water, filtering and drying are carried out with the simultaneous use of cycles including heating the material to a temperature of 115 ° C or less, high-speed pulse exposure to vacuum with pressure ranging up to 5 mmHg Art., in less than 10 seconds, followed by exposure to vacuum, for example, until a constant temperature is reached and the vacuum is released.

As a hydrolysis solution, a solution of nitric or sulfuric acids, or a mixture of nitric and sulfuric acids with a concentration of solutions of not more than 15.0% can be used with a ratio of cellulose-containing raw materials to the hydrolysis solution (module) of not more than 1: 15.

As a hydrolysis solution, an alkaline solution with a solution concentration of less than 30 grams / liter can be used with a ratio of cellulose-containing raw materials to hydrolysis solution (module) of not more than 1: 15.

As a hydrolysis solution, you can use a solution of waste acids for the production of cellulose nitrates, which is less expensive, because to return to the production of SCs, their regeneration is required.

After impregnation, annual cellulose-containing plants in order to maintain the optimal fiber length for textiles, medical cotton wool, etc., are subjected to razvoleniye, for SC production, these plants are subjected to grinding during hydrolysis.

To increase the homogeneity of cellulose and to intensify subsequent operations, the hydrolysis of raw materials in a hydrolysis solution for SC production and other materials is carried out with simultaneous grinding.

The impurities dissolved in it, such as lignin, hemicellulose, pectins, pentosans, etc., are separated from the spent hydrolysis solution from the cellulose fiber, followed by their planting and production of fertilizers based on them in a simpler way than in the production of sulfate cellulose.

After washing and filtering the cellulose, the wash water is regenerated with the organization of water circulation for subsequent use.

If necessary, after washing the pulp, it is bleached using cycles that include heating the material to a temperature of 115 ° C or less, high-speed pulse exposure to vacuum with a pressure change in the range up to 5 mm Hg. Art., in a time less than 30 seconds, followed by exposure to vacuum, for example, until a constant temperature is reached and the vacuum is released. If necessary, to maximize the integrity of the fiber length, some types of cellulose, after washing with water and filtering, squeeze the vacuum on a mesh or fabric filter by pulsed suction of water with a pull of air coolant through a layer of fibrous cellulose and a mesh until the desired moisture content is reached, followed by loosening of the compacted cellulose.

The technical result is achieved due to the fact that all stages of the process are accompanied by cycles, including heating the material to a temperature of 115 ° C or less, high-speed pulsed exposure to vacuum with a change in pressure in the range up to 5 mm RT. Art. in less than 10 seconds, followed by exposure to vacuum and vacuum relief. High-speed pulsed exposure to vacuum is carried out using a receiver and pipelines equipped with high-speed valves. This leads to the intensification of mass transfer with the acceleration of the process of hydrolysis of the material and other advantages.

Impregnation in a hydrolysis solution.

The impregnation of cellulose-containing raw materials with simultaneous exposure to cycles, including high-speed pulsed vacuum, is carried out in a hydrolysis solution. The impact of a high-speed pulsed vacuum during the impregnation improves the wettability, degasses the treated mixture, facilitating the penetration of the hydrolysis solution into the fibers of the raw material, reduces the duration of the impregnation, accelerating the dissolution of lignin, freeing the cellulosic part of the raw material from other impurities.

Hydrolysis.

Prepared, impregnated with a hydrolysis solution, the raw material is subjected to hydrolysis. During high-speed pulsed exposure to vacuum during hydrolysis, capillaries of heated cellulosic material during pulsed evacuation remove moisture vapor, air and gases dissolved in moisture, rupture of part of the membrane walls, and when the vacuum is released, not only capillaries are impregnated with the hydrolysis solution, but also the structure of the cellulosic material. Thus, the destruction of cellulosic material by high-speed pulsed vacuum ensures the rapid penetration of the hydrolysis solution into the cellulosic material with the dissolution of lignin, hemicellulose and other impurities from destructible cellulose with the formation of chemically and structurally homogeneous cellulose from all known types of cellulose-containing materials with bast fibers.

With high-speed pulsed exposure to vacuum, a high uniformity of hydrolysis of the material is achieved due to hydrolysis under pulsed exposure to vacuum simultaneously over the entire volume of the reactor at strictly specified temperature values and the duration of the process. Eliminates the need for some additional reagents. At constant temperature values, the required parameters of a particular pulp are achieved by the number of cycles of high-speed pulsed exposure to vacuum on the material, and not by using an elevated process temperature.

The hydrolysis of various cellulose-containing raw materials can be carried out in an alkaline or acidic environment. Hydrolysis in an alkaline medium proceeds more slowly than in an acidic medium, in which the wettability of the material and the diffusion of the solution into the material are improved. With high-speed pulsed exposure to vacuum, the wettability of materials improves, therefore, the hydrolysis of cellulose-containing materials can be carried out both in alkaline and in acidic environments. Given the versatility of the developed process, preference is given to hydrolysis with acidic solutions, both from the standpoint of simplifying the composition of the hydrolysis solution, and from the standpoint of intensifying the hydrolysis process, lowering the process temperature, as well as obtaining high-quality low-viscosity cellulose. See examples 1 and 2 below.

By lowering the hydrolysis temperature with uniform processing of the material, a greater conservation of the crystalline part of cellulose is achieved with an increase in its yield.

The alternation of cycles of heating the material to the optimum temperature, vacuum collection and discharge, intensifies mass transfer, accelerating the process of hydrolysis of the material and dissolving lignin and other impurities, degrading cellulose to the required viscosity values for a particular cellulose, for example, textile, medical cotton, paper and nitrocellulose production . At the same time, there is no need to use elevated temperatures and to increase the duration of the process, and, as experimental work shows, hydrolysis for different materials should be carried out at a temperature of 115 ° C or less for about 10-60 minutes and, importantly, without the use of state technical supervision equipment .

At these temperatures, the required degree of polymerization is achieved, since a high-speed pulsed exposure to vacuum impregnates the entire volume of the crushed material at low concentrations of reagents 0.5-3.0% for 0.5-1.5 hours (example 3, which is shown below).

The cellulose-containing raw material is impregnated and hydrolyzed in a hydrolysis solution medium, where a solution of nitric, sulfuric acids, or a mixture of nitric and sulfuric acids with a concentration of solutions of not more than 15.0% is used as a hydrolysis solution with a ratio of cellulose-containing raw materials to hydrolysis solution of not more than 1:15. The combined effect of acids favorably affects hydrolysis, improving the uniformity of cellulose from wood and annual plants.

Lignin is subsequently converted to organic fertilizer, increasing crop yields.

The impregnation and hydrolysis of cellulose-containing raw materials is also carried out in an environment where an alkaline solution with a concentration of less than 30 grams / liter is used as the hydrolysis solution with a ratio of cellulose-containing raw materials to the hydrolysis solution of not more than 1:15.

The impregnation and hydrolysis of cellulose-containing raw materials can be carried out with a solution of waste acids from the production of cellulose nitrates, which are a mixture of nitric, sulfuric acids and water. In spent acid, depending on the composition of the initial working acid mixture, the content of nitric acid reaches 20-28%, sulfuric acid up to 60% and water up to 20%, which allows you to create the necessary hydrolysis solution. The use of spent acids minimizes the cost of the hydrolysis solution.

To obtain the required viscosity values of cellulose from annual plants for textiles, medical cotton wool, and some grades of paper, etc., after impregnation to maintain the optimal fiber length, they are subjected to rafting. The process of hydrolysis of raw materials in a hydrolysis solution is activated when combined with grinding, for example, wood up to 10-50 microns, which increases the uniformity of cellulose and intensifies subsequent operations.

Filtration of the resulting pulp.

After the hydrolysis of the cellulose-containing raw materials in the medium of the hydrolysis solution is completed, the resulting cellulose is filtered to separate from the spent hydrolysis solution while using the above cycles, including high-speed pulsed vacuum. A large pressure drop across the filter material increases the productivity of the process of separating the hydrolysis solution with the impurities dissolved in it from the cellulose fiber. The dissolved impurities in the spent hydrolysis solution are subsequently precipitated together with lignin.

Flushing with water.

After filtering the resulting cellulose, washing is carried out with the simultaneous use of the above cycles, including high-speed pulsed exposure to vacuum, with water heated to 50-70 ° C, then with a temperature of 15-25 ° C in order to remove residual hydrolysis solution adsorbed on the surface of lignin fiber, etc. Impurities and low molecular weight hydrolysis products. At the same time, they are intensifying mass transfer processes, especially when boiling water with pulsed evacuation throughout the volume of the solution. Cellulose is washed to a neutral environment.

After washing, if necessary (for medical cotton wool, textiles, paper, nitrovarnishes and enamels), the cellulose is bleached. Bleaching is carried out mainly with hydrogen peroxide using cycles that include heating the material to a temperature of 115 ° C or less, high-speed pulsed exposure to vacuum with a pressure change in the range up to 5 mm RT. Art., in a time less than 30 seconds, followed by exposure to vacuum and vacuum discharge.

Filtration.

After washing the cellulose with water, it is filtered using high-speed pulsed vacuum, similar to filtration after hydrolysis. The separated wash water is sent for regeneration for reuse.

Drying.

Cellulose is dried using the above cycles, including high-speed pulsed exposure to vacuum, which makes it possible to obtain cellulose with less than 10% moisture, due to better desorption of surface moisture and positively directed gradients of pressure, temperature and humidity of cellulose. Deeper and more uniform drying occurs at a cellulose temperature of less than 100 ° C.

If necessary, for fibrous materials (fabric, etc.), before washing, the cellulose washed and filtered from rinsing water is squeezed on a mesh or fabric filter using a high-speed pulsed vacuum suction of water with an air heat carrier through a layer of fibrous cellulose and a mesh to not more than 10% humidity. Subsequently, the densified pulp is loosened.

Thus, the use of high-speed pulse effects of vacuum at all stages of the process of producing cellulose gives the following advantages of the method: reducing the duration of the process of hydrolysis of cellulose by an order of magnitude, the possibility of creating a closed cycle of water circulation, as well as hydrolyzing and bleaching solutions, lowering the temperature of the processes to obtain the required chemical and structural uniformity material, with the achievement of greater conservation of the crystalline part of the cellulose with faster destruction of the amorphous part of the cellulose oses, the possibility of obtaining the desired grade of pulp from any cellulose-containing raw material. The exclusion of additional chemicals from the hydrolysis solution improves the ecology of not only the air basin, but also the water basin by reducing the volume of washing water with the organization of their regeneration. The regeneration of used hydrolysis, bleaching solutions and wash water is greatly simplified. Simplified pulp separation technology lignin and other impurities and the process of obtaining high-quality homogeneous cellulose.

Examples of the method.

Example 1

Experimental work on obtaining homogenized cellulose began with the manufacture in laboratory conditions of hydrolyzed cotton pulp from cotton lint, not alkaline cooking in an environment of 10-15 grams / liter of alkali, but in an acidic environment.

Moreover, all processes are carried out with the simultaneous use of the above cycles, including high-speed pulse effects of vacuum.

Cotton lint is impregnated with high-speed pulsed vacuum

A 2.0% solution of spent acid produced by the SC for 15 minutes at a temperature of 95 ° C. Lint hydrolysis is combined with grinding in a laboratory apparatus up to 50-100 microns. In the receiving tank at high-speed pulsed effects of vacuum in the medium of this hydrolysis solution, the viscosity of the cellulose decreases to 5-10 cps. Then the cellulose is filtered, washed, squeezed in a centrifuge. Cellulose for nitro-lacquers and enamels is bleached at high-speed pulsed exposure to vacuum with a mixture of aqueous solutions of alkali with a concentration of 5 grams / liter and hydrogen peroxide with a concentration of 8 grams / liter at 75 ° C for 30 minutes. Bleached cellulose is separated from the solution, washed, squeezed and dried by high-speed pulsed vacuum.

Technical indicators of the obtained cellulose: mass fraction of alpha-cellulose 97-98%, wettability -167.5 g, dynamic viscosity - 8.3 MPa * s, humidity - 8%. Thus, it was proved that cotton cellulose is obtained not by alkaline but by acid hydrolysis. The cellulose produced has a lower viscosity, high whiteness and solubility of varnish and enamel samples in a combined solvent, reaching 98.5%, the varnishes are transparent.

Example 2

Obtaining medical cotton wool from long-fiber cotton in the laboratory. In alkaline cooking, a solution of NaOH with a concentration of 25 grams / liter is used, the process is carried out at a module of 1: 20, a temperature of 140 ° C for 4 hours.

In the laboratory, cotton hydrolysis is carried out using cycles in all processes, including high-speed pulsed exposure to vacuum, a 2.5% melange solution at 60 ° C and a 1: 7.5 module for 50 minutes. Impregnation of cotton is carried out with a change in pressure by high-speed pulse effects of vacuum up to 10 mm RT. Art. After hydrolysis, the hydrolysis solution is filtered from cotton. Hydrolysis the solution is regenerated and put back into circulation. The fiber is washed with water at a temperature of 60 ° C and then with water at a temperature of 20 ° C with a module of 1: 7.5 to a neutral environment. Wash water after two-stage (10 and 5 μm) filtration and pH adjustment are reused. The washed fiber is bleached with a mixture of aqueous solutions of alkali with a concentration of 3 grams / liter and hydrogen peroxide with a concentration of 8 grams / liter at a temperature of 70 ° C for 30 minutes with high-speed pulsed vacuum. Then, the bleaching solution is separated from cellulose, the solution is filtered twice, regenerated and returned to the technological cycle. This is followed by washing the cellulose with water under high-speed pulsed exposure to vacuum. Water at high-speed pulsed effects of vacuum is also filtered, adjusted by pH and reused. Bleached, washed cellulose is squeezed on a continuous, conveyor screen or fabric filter with pressure rolls and then dried by drawing in an air coolant with a temperature of 100-115 ° C through a layer of cellulose and a mesh to 5-10% moisture by high-speed pulsed vacuum, followed by loosening of the compacted pulp.

The resulting medical cotton wool is soft and meets the requirements of TU in terms of parameters and has increased wettability. Humidity - 8%, whiteness - 80%.

Example 3

Experimental work on obtaining textile fibers from flax and hemp.

After drying, hemp stalks, like flax, are subjected, using cycles including high-speed pulsed vacuum, to preliminary hydrolysis at a temperature of 95 ° С with a 3.0% melange solution at a module of 1: 7.5. The impregnated fiber is subjected to hydrolysis, where it is brought to the required viscosity standards.

At the same time, to obtain long fibers for textiles, medical cotton wool, flax and hemp paper, they are washed twice with water at a temperature of 60 ° C and then at a temperature of 20 ° C to a neutral environment, when using cycles with high-speed pulsed vacuum, they are dried at a temperature 95 ° C and flax and hemp stalks are passed through corrugated rollers with a gap of 1.0 - 1.5 mm, with crushing of the stems, and partial separation of the fibers from the bonfire on bobbin machines. After filtration, the washed fiber is bleached with an alkaline peroxide solution, the solution is separated, the fiber is washed and subjected to extraction and drying on a continuous conveyor screen apparatus with pressure rollers and suction of an air coolant with a temperature of 98 ° C and high-speed pulse effects of vacuum through the fiber layer and the net. Fiber drying is carried out up to 10% humidity, loosens roll machine and then packaged in bales. Achieved the degree of polymerization of flax fiber - 10000, the degree of polymerization of hemp - 8000.

Example 4

Obtaining cellulose from hemp for SC production with the simultaneous use of cycles, including high-speed pulsed exposure to vacuum at all stages of the process.

In laboratory conditions, after the fiber is impregnated in a 3% melange solution, the fiber is pulverized by hydrolysis in a solution with a temperature of 95-98 ° C with a 1: 5 module to 50-100 μm, the viscosity of cellulose decreases to 5-10 cPs. The hydrolysis solution is also separated from the fiber. The hydrolysis solution is filtered off, lignin and impurities are precipitated, after regeneration, the solution is returned to the technological cycle. The cellulose used to make SCs for nitro-lacquers and enamels is bleached in an aqueous alkaline peroxide solution. The solution is filtered, regenerated and returned to the technological cycle. Bleached pulp is washed, squeezed and dried. Cellulose fibers are washed to a neutral medium, squeezed in a centrifuge or screw press under high-speed pulsed vacuum. On the press, cellulose is pressed through a heated cone press tool with dies and squeezed to a moisture content of 15-20%. The cellulose is vacuum-packed in a dense layer into a vacuum-pulse continuous dryer and dried at a temperature of 110 ° C for 30 minutes to a moisture content of not more than 10% and is packed. At the consumer's plant, cellulose is impregnated with high-speed pulsed vacuum in a particular solution and dissolves into fibers.

Example 5

Experimental work on the production of sulfate hydrolysis of wood pulp was carried out using cycles involving high-speed pulsed vacuum effects at all stages.

Wood chips with a thickness of 5 mm, a width of 10 mm and a length of 14 mm are subjected to impregnation at high-speed pulsed exposure to vacuum with a solution of sodium hydroxide and sodium sulfide at a concentration of 10 grams / liter at 95 ° C, a module of 1: 7.5 with a pressure change of up to 10 mm RT. Art. within 30 minutes. Next, the grinding of chips with an alkaline hydrolysis solution is carried out on a laboratory grinder to a particle size of 50-100 microns. At high-speed pulsed exposure to vacuum at 95 ° C, the hydrolysis of crushed wood chips in an alkaline medium is brought to 10-15 cPs for 1 hour. The hydrolysis solution with dissolved lignin and other impurities is filtered through woven metal mesh with mesh sizes of 50, 10 and 5 microns. Cellulose fiber after separation of hydrolysis the solution is washed with water at a temperature of 60 ° C and water at a temperature of 20 ° C to a neutral environment. Washed cellulose, for better purification from impurities and finely dispersed finely divided amorphous cellulose, is subjected to additional acid hydrolysis with a 3.0% solution of mélange at 90-95 ° C using high-speed pulsed exposure to vacuum for 60 minutes, reducing the viscosity of the pulp to 9-10 cps. The hydrolysis solution is filtered. The fiber is washed, squeezed in a laboratory centrifuge and dried to 8-10% moisture. In the manufacture of cellulose for varnishes and enamels, it is bleached with a mixture of alkali solution (NaOH) of concentration - 4-5 grams / liter and hydrogen peroxide - 10 grams / liter at 70-75 ° C for 15 minutes, followed by filtration of the bleaching solution, washing, pressing and drying at a temperature of 115 ° C to a moisture content of 10% cellulose.

The content of alpha-cellulose reaches 96-97%, wettability - 150-160 g, humidity - 8-10%, viscosity - 6-9 cps, degree of polymerization - 260.

Example 6

In laboratory conditions, wood chips are subjected to impregnation with a solution of melange with a concentration of 2.5% at 95-98 ° C and a module of 1: 7.5 with the simultaneous use at this and subsequent stages of cycles involving high-speed pulsed exposure to vacuum with a pressure change of up to 10 mm Hg. Art. within 30 minutes. Chips are crushed in a hydrolysis solution to a particle size of 50-100 microns. The required viscosity of the pulp is achieved in the grinding process.

For wood with a high resin content, the required viscosity indices are achieved by high-speed pulsed vacuum influences. The hydrolysis solution is filtered by high-speed pulsed vacuum through a stainless steel mesh with cells of 10 and 5 μm, and is regenerated by chemical composition with the organization of the circulation of the solution in a closed cycle. The separated cellulose is washed twice with water at a temperature of 50-60 ° C and then with water at a temperature of 20 ° C. Wash water by high-speed pulsed vacuum is filtered through a stainless steel mesh with mesh sizes of 10 and then 5 microns. The waters are regenerated by launch vehicle with the organization of a closed water circulation. The washed cellulose is bleached with a mixture of aqueous solutions of alkali NaOH with a concentration of 3-6 grams / liter and hydrogen peroxide with a concentration of at least 8 grams / liter at a temperature of 50-75 ° C for 30 minutes, followed by stepwise filtration and regeneration of the solution, washing water, s the organization of the turnover of the solution and water. Cellulose bleaching is necessary only for transparent nitro lacquers and enamels. The resulting cellulose is squeezed in a centrifuge using a suction of squeezed water by high-speed pulsed vacuum. On the screw press, cellulose through heated a cone-shaped press with a cowl is pressed through dies with a moisture content of 15-20%. Cellulose drying is carried out in a continuous vacuum dryer using high-speed pulse effects of vacuum at a temperature of 110 ° C to a moisture content of 10%.

The content in the resulting cellulose alpha-cellulose - 96-97%, wettability - 150-

160, viscosity - 5-9 cPs, humidity - 4-8%, degree of polymerization - 220-240.

Example 7

In laboratory conditions, the possibility of producing sulfite wood pulp using cycles involving high-speed pulsed vacuum exposure at all stages and by grinding wood chips in a sulfuric acid medium was tested. To obtain sulfite cellulose, wood chips are impregnated with sulfuric acid (H2SO3), as well as the grinding of wood chips in the medium of this hydrolysis solution up to 50-100 μm with a solution of this acid at a concentration of 10% at a temperature of 85-75 ° C for 1 hour. Next, the hydrolysis solution containing the lignin solution and other impurities is filtered. The fiber is washed to a neutral medium, squeezed in a centrifuge. Further, wood chips are impregnated with nitric acid at a concentration of 8.0%, without the use of Ca (HS0 ₃ ) ₂ solution, without S0 ₂ penetrating the wood chips faster than the solution, and also without the use of alcohols (butyl and others), as well as without phenol, ethylene glycol and organic acids (acetic, monochloroacetic and other acids).

The hydrolysis solution is separated in a centrifuge with the planting of dissolved impurities. The fiber is washed to a neutral medium, squeezed in a centrifuge and dried to 10% humidity.

If necessary, the cellulose is bleached with a NaOH solution mixed with hydrogen peroxide to separate, regenerate the solution, rinse and dry the cellulose to 10% moisture.

Alpha cellulose content reaches up to 97%, wettability up to 150g, degree of polymerization - 240, humidity - 10%.

Consequently, with high-speed pulsed vacuum effects during the hydrolysis of wood chips when combining the process with grinding, we obtain from wood chips and sulfite cellulose in a two-stage mode: first in an alkaline solution of sodium hydroxide and sodium sulfide, then after separation of the alkaline solution and washing in a melange solution with adjusting the modes to obtain finished products with improved pulp characteristics.

Claims

FORMULA

1. A method of producing cellulose by processing cellulose-containing raw materials, including impregnating and hydrolyzing the raw material in a hydrolysis solution medium, filtering the resulting cellulose, subsequent washing with water, filtering and drying, characterized in that the impregnation and hydrolysis processes in the hydrolysis solution medium, filtering the resulting cellulose, washing water, filtration and drying are carried out using cycles that include heating the material to a temperature of 115 ° C or less, high-speed pulse exposure to vacuum with a change in pressure in pazone to 5 mm Hg. Art. in less than 10 seconds, followed by exposure to vacuum and vacuum relief.

2. The method according to claim 1, characterized in that a solution of nitric or sulfuric acids or a mixture of nitric and sulfuric acids with a concentration of solutions of not more than 15.0% is used as a hydrolysis solution with a ratio of cellulose-containing raw materials to hydrolysis solution of not more than 1: 15 .

3. The method according to paragraph 1, characterized in that as the hydrolysis solution using an alkaline solution with a solution concentration of less than 30 grams / liter with a ratio of cellulose-containing raw materials to the hydrolysis solution of not more than 1:15.

4. The method according to paragraph 1, characterized in that as a hydrolysis solution using a solution of waste acids of nitrocellulose production.

5. The method according to claim 1, characterized in that the annual cellulose-containing plant material after being impregnated in the hydrolysis solution medium is subjected to razvolka.

6. The method according to paragraph 1, characterized in that the hydrolysis of the feedstock in the hydrolysis solution is carried out while grinding the feedstock to increase the uniformity of the pulp and to intensify subsequent operations.

7. The method according to paragraph 1, characterized in that they produce separation from the spent hydrolysis solution of the impurities dissolved in it.

8. The method according to paragraph 1, characterized in that after washing the pulp and filtering the wash water is regenerated to organize the circulation of water.

9. The method according to paragraph 1, characterized in that after washing the pulp, it is bleached using cycles that include heating the material to a temperature of 115 ° C or less, high-speed pulse exposure to vacuum with a pressure change in the range up to 5 mm RT. Art., in a time less than 30 seconds, followed by exposure to vacuum and vacuum discharge.

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SUBSTITUTE SHEET (RULE 26)

10. The method according to paragraph 1, characterized in that after washing with water and filtering the cellulose in order to maximize the integrity of the fiber length, squeeze it on a mesh or fabric filter with pressure rollers by vacuum-pulsed suction of water with an air heat carrier through a layer of fibrous cellulose and a mesh to achieve the desired humidity, followed by loosening of the compacted pulp.

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SUBSTITUTE SHEET (RULE 26)