Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C1/00—Pretreatment of the finely-divided materials before digesting
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C1/00—Pretreatment of the finely-divided materials before digesting
  • D21C1/02—Pretreatment of the finely-divided materials before digesting with water or steam
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/001—Modification of pulp properties
  • D21C9/007—Modification of pulp properties by mechanical or physical means

Definitions

• the invention relates to the chemical industry, namely to the production of the cellulose from all types of plant cellulose-containing material, chemically and structurally homogeneous, bleached and unbleached cellulose, for paper, textile, medical, nitrocellulose industry (hereafter referred to as NC), paint and powder technologies, which can be used for further processing in various industries: NC for powders, varnishes, enamels, textile, paper, medical, pharmaceutical, food etc.
• NC for powders, varnishes, enamels, textile, paper, medical, pharmaceutical, food etc.
• the wood of coniferous and hardwoods, cotton, flax, hemp, fruit shells of cereal crops (oats, etc.), straw of cereals, as well as bamboo, miscanthus, amaranth, bagas, esparto, etc., are used as cellulose-containing raw materials.
• the use of high (up to 1.5 MPa) pressure for boiler-reactors of large (up to 400 m 3 and more) volume with application of high temperatures complicates the technological process and its implementation.
• the group of acidic processes for cellulose production includes sulphite, inorganic (HNO 3 , HCl), organic (acetic, monochloroacetic, etc.) acids are used as reagents, as well as ethylene glycol, phenol, butyl alcohol and other alcohols., as well as calcium-base solution, containing Ca(HSO 3 ) 2 with an excess of SO 2 , supporting pH of the solution at a level of 1.2-1.5.
• SO 2 which has strong acidic properties, penetrates into wood chips faster than the solution, so the solution is heated more slowly, otherwise incomplete delignification of wood occurs.
• the temperature of the solution in the production of paper pulp lies in the range of 125-135°C, and for pulp for chemical industry is 145° C, the processing time is up to 12 hours.
• the use of this method leads to deterioration of the sorption properties of resulting cellulose, its structural and chemical heterogeneity, reduced degree of crystallinity, and reduced stability of properties during storage.
• the obtained celluloses especially when being produced by the sulphate method, the cellulose is molecularly heterogeneous.
• the final characteristics of celluloses have increased spreads in viscosity, content of ⁇ -cellulose, etc.
• a method for producing fibrous cellulose from a cellulose-containing raw material is known, with the use of an aqueous solution of nitric acid as a delignifying agent (RF patent No. 2353626 , IPC C08B1/04; D01F2/00, dated October 25, 2007).
• the treating solution contains surfactants, an ammonium inorganic salt, or potassium or sodium nitrate.
• Oxidative treatment is carried out in an alkaline-peroxide solution containing sodium carboxymethyl cellulose and nonionic water-soluble cellulose ether.
• a method for producing a cellulose by cooking wood chips of hardwood in a sulphite cooking solution and subsequent washing is known (RF patent No. 2010069 , IPC D21C 3/06 of 08.07.1992).
• a mixture of crude turpentine sulphite with a Na 2 O content of 1.45-1.65% and total SO 2 4.2-4.8%, and an aqueous solution of sodium carbonate with a concentration of 90-110 g/l under their volumetric ratio from 100:3 to 100:5 as a cooking liquor is used, and the cooking is carried out in the cooking liquor under the content of bound SO 2 1.75-2.25% and Na 2 O 1.65-2.18% and pH 2.5-4.0 .
• the cooking is carried out at a concentration of total SO 2 of 3.8-4.5%.
• This method is used to produce cellulose from wood chips of hardwoods or from low-resin wood species: spruce, fir.
• the disadvantage of the method is the use of a composition of reagents that deteriorate the ecological environment of air and water basins.
• the resulting cellulose does not have sufficient chemical and structural homogeneity.
• a method for producing cellulose from non-wood plant raw material with a content of native cellulose of not more than 50% and an aqueous solution of sodium hydroxide (RF patent No. 2448118 , IPC C08B 11/12, 1/00, 1/02 , dated 09.11.2010) is known.
• the raw material is washed with hot water at the temperature of 40-75°C under atmospheric pressure for 0.5-4.0 hours, delignification is carried out at the temperature of 90-95°C with an aqueous solution of nitric acid with a concentration of 2-8% for 4-20 hours.
• Further cellulose is subjected to additional treatment with sodium hydroxide solution of 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 cellulose quality, in particular, to a decrease in the strength index.
• a method for processing cellulose-containing raw materials has been selected (RF patent No. 2456394 of the IPC D21C 1/02, 3/02, 9/10, 9/16, 11/04, C07G 1/00, dated 08.12.2010), where the processing of cellulose-containing raw materials is carried out by the following stages of the technological process: prehydrolysis (impregnation), cooking (hydrolysis) of lignocellulose in 30% hydrotropic solution for 1-3 hours , filtration of the obtained cellulose, washing it with 30% hydrotropic solution, subsequent washing with water, bleaching the cellulose with hydrogen peroxide in solution of sodium hydroxide to obtain a bleached cellulose, treatment it with an acid solution followed by treatment with a solvent, filtration and drying. Miscanthus or fruit shells of cereal crops, or straw of cereal crops are used as cellulose-containing raw material.
• miscanthus or fruit casings of cereal crops, or straw of cereal crops are used to produce cellulose, however, the resulting pulp does not have sufficient chemical and structural homogeneity.
• the object of the invention is to provide a method for producing the cellulose of improved quality, with chemical and structural homogeneity from various types of cellulose-containing raw materials while simplifying and making cheaper the manufacturing process.
• the desired object is achieved by processing a cellulose-containing raw material comprising impregnating and hydrolysis of the raw material in a hydrolysis solution, filtration the resulting cellulose, subsequent washing with water, filtration and drying, in which, according to the invention, the impregnation and hydrolysis of the raw material in the hydrolysis solution, filtration of the resulting cellulose, washing with water, filtration and drying are carried out with simultaneous use of cycles involving the heating of the material to a temperature of 115°C or less, high-speed vacuum-impulse action with a pressure change in the range up to 5 mm Hg for a time of less than 10 seconds, followed by exposure under vacuum, for example, until a constant temperature achievement and vacuum relief.
• a solution of nitric or sulphuric acids or mixtures of nitric and sulphuric acids with a solution concentration of not more than 15.0% can be used at a ratio of the cellulose-containing raw material to the hydrolysis solution (module) no more than 1:15.
• an alkaline solution with a solution concentration of less than 30 grams/liter can be used at a ratio of the cellulose-containing feed to the hydrolysis solution (module) of not more than 1:15.
• a hydrolysis solution a solution of waste acids produced by the production of cellulose nitrates can be used, which is less expensive, since to return NC to the production their regeneration is required.
• the hydrolysis of the raw material in the hydrolysis solution for NC-production and other materials is carried out with simultaneous disintegration.
• Impurities dissolved in spent hydrolysis solution are separated, such impurities as lignin, hemicellulose, pectins, pentosans, etc. are separated from the cellulose fiber, followed by their precipitation and the production of fertilizers based on them according to a simpler scheme than in the production of sulphate cellulose.
• the technical result is achieved due to the fact that all the stages of the technological process are accompanied by cycles, including heating the material to a temperature of 115°C or less, high-speed vacuum-impulse action with a pressure change in the range up to 5 mm Hg for a time of less than 10 seconds, followed by exposure under vacuum and vacuum relief.
• High-speed impulse action of vacuum is carried out with the aid of a receiver and pipelines equipped with high-speed valves. This leads to an intensification of mass transfer with the acceleration of the process of hydrolysis of the material and other advantages.
• Impregnation in a hydrolysis solution Impregnation in a hydrolysis solution.
• Impregnation of cellulose-containing raw materials with simultaneous action of cycles involving high-speed impulse actions of vacuum is carried out in the hydrolysis solution.
• the action of high-speed impulse vacuum during impregnation improves wettability, degasses the treated mixture, facilitating the penetration of the hydrolysis solution into the raw materials' fibers, reduces the impregnation time, accelerates the dissolution of lignin, and separating the cellulosic part of the raw material from other impurities.
• the prepared and impregnated with the hydrolysis solution raw material is subjected to hydrolysis.
• hydrolysis Under a high-speed impulse action of the vacuum during the process of hydrolysis, from the capillaries of the heated cellulosic material and under impulse vacuuming, the moisture vapors, air and dissolved gases in the moisture are removed, the break of a part of the membrane walls takes place and when the vacuum is released, the impregnation by the hydrolytic solution of not only the capillaries but also the structure of the cellulosic material occurs.
• Hydrolysis of various cellulose-containing raw materials can be carried out in an alkaline or acidic medium. Hydrolysis in an alkaline medium proceeds slower than in an acidic medium, in which the wettability of the material and the solution diffusion into the material improve. With the high-speed impulse action of vacuum, the wettability of the materials is improved, so the hydrolysis of cellulose-containing materials can be carried out both in alkaline and in acid media. Taking into account the universality of the technological process being developed, the preference is given to hydrolysis with acidic solutions, both from the viewpoint of simplifying the composition of the hydrolysis solution, and from the viewpoint of intensifying the hydrolysis process, lowering the process temperature, and obtaining high-quality low-viscosity cellulose. See examples 1 and 2 below.
• Impregnation and hydrolysis of cellulose-containing raw materials is carried out in a hydrolysis solution medium, where as a hydrolysis solution, a solution of nitric or sulphuric acids or mixtures of nitric and sulphuric acids with a solution concentration of not more than 15.0% is used at a ratio of the cellulose-containing raw material to the hydrolysis solution not more than 1:15.
• a hydrolysis solution a solution of nitric or sulphuric acids or mixtures of nitric and sulphuric acids with a solution concentration of not more than 15.0% is used at a ratio of the cellulose-containing raw material to the hydrolysis solution not more than 1:15.
• the combined effect of acids favorably affects hydrolysis, improving the homogeneity of cellulose from wood and annual plants.
• Lignin is subsequently converted to organic fertilizer, which increases crop yields.
• Impregnation and hydrolysis of the cellulose-containing raw material is also carried out in a medium, where an alkaline solution with a concentration of less than 30 grams/liter is used as the hydrolysis solution at a ratio of the cellulose-containing raw material to the hydrolysis solution of not more than 1:15.
• 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 is a mixture of nitric, sulphuric acids and water.
• waste acids from the production of cellulose nitrates, which is a mixture of nitric, sulphuric acids and water.
• spent acid depending on the composition of the initial working acid mixture, the nitric acid content reaches 20-28%, sulphuric acid up to 60% and water up to 20%, which allows creating the necessary hydrolysis solution.
• the use of spent acids minimizes the cost of the hydrolysis solution.
• the fibers are subjected to defibration.
• the process of hydrolysis of raw materials in the hydrolysis solution is activated when being combined with disintegration of, for example, wood up to 10-50 microns, which increases the homogeneity of the cellulose and intensifies subsequent operations.
• the obtained cellulose is filtered to separate it from the spent hydrolysis solution while using the above cycles, including the high-speed impulse action of vacuum.
• a great pressure drop on the filtering material increases the productivity of the process of separating the hydrolysis solution with the impurities dissolved therein from the cellulose fiber. Dissolved in the spent hydrolyzed solution impurities are subsequently precipitated together with lignin.
• a washing is carried out with the simultaneous use of the above cycles, including a high-speed impulse action of vacuum, with water heated to 50-70°C, further at a temperature of 15-25°C to remove the residues of the hydrolysis solution adsorbed on the surface of the lignin fiber and others impurities and low molecular weight hydrolysis products.
• mass-exchange processes are intensified, especially when boiling water during impulse vacuuming throughout the volume of the solution. The cellulose is washed until neutral pH.
• Bleaching is performed mainly by hydrogen peroxide with using cycles that include heating of the material to a temperature of 115°C or less, high-speed vacuum-impulse action of vacuum with a pressure change in the range up to 5 mm Hg for a time of less than 10 seconds, followed by exposure under vacuum and vacuum relief.
• Drying of cellulose is carried out using the above cycles, including high-speed impulse action of vacuum, which makes it possible to obtain cellulose less than 10% moisture, due to better desorption of surface moisture and positively directed pressure gradients of temperature and moisture of cellulose. At a cellulose temperature of less than 100°C a deeper and uniform drying takes place.
• the cellulose washed and filtered from the washings is squeezed on the mesh or fabric filters by high-speed impulse vacuum suction of water with the passing of an air heating medium through a layer of fibrous cellulose and a mesh up to not more than 10% of moisture. Subsequently, the compacted cellulose is loosened.
• the use of high-speed impulse of vacuum actions at all stages of the process of obtaining cellulose gives the following advantages for the process: reducing the duration of cellulose hydrolysis process by an order of magnitude, the possibility of creating closed-loop water circulation, as well as hydrolysis and bleaching solutions, decrease of process temperatures when obtaining the desired chemical and structural homogeneity of material, with achievement a greater maintenance of the crystalline part of cellulose with a faster degradation of the amorphous part of cellulose, and the possibility of obtaining the desired grade of cellulose from any cellulose-containing material.
• the exclusion of additional chemicals from the hydrolysis solution improves the environment not only of the air basin, but also of the water basin by reducing the volumes of washing water with the organization of their regeneration process.
• the regeneration of used hydrolysis, bleaching solutions and washing water is greatly simplified.
• the technology of separating lignin and other impurities from cellulose and the technological process for obtaining high-quality homogeneous cellulose are simplified.
• the cotton lint is impregnated with a 2.0% solution of spent acid from the production of NC for 15 minutes at a temperature of 95°C. Hydrolysis of linters is combined with disintegration up to 50-100 microns in a laboratory apparatus.
• the viscosity of cellulose decreases to 5-10 cPs. Further, the cellulose is filtered, washed, and squeezed out on a centrifuge.
• Cellulose for nitrocellulose varnishes and enamels is bleached under high-speed impulse actions of vacuum with a mixture of aqueous solutions of alkali concentration of 5 grams/liter and hydrogen peroxide of 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 impulse actions of vacuum.
• the hydrolysis of cotton is carried out using all cycles, including high-speed impulse action of vacuum, by 2.5% melange solution at 60°C and module 1:7.5 module for 50 minutes. Impregnation of cotton is carried out with a change in pressure by high-speed impulse actions of vacuum up to 10 mm Hg.
• the hydrolysis solution is filtered from cotton. The hydrolysis solution is regenerated and recycled again.
• the fiber is washed with water at a temperature of 60°C and further water at a temperature of 20°C with a modulus of 1:7.5 to neutral medium. Washing water after a two-stage (10 and 5 ⁇ m) filtration and adjustment for pH is re-used.
• the washed fiber is bleached with a mixture of aqueous alkali solutions with a concentration of 3 grams/liter and hydrogen peroxide of 8 g/liter at 70°C for 30 minutes at high-speed pulsed actions of vacuum. Then, the bleaching solution is separated from the cellulose; the solution is filtered twice, regenerated and recycled. Then the washing of cellulose with water at a high-speed impulse action of vacuum follows. Water at high-speed impulse actions of vacuum is also filtered, adjusted for pH and reused.
• Bleached, washed cellulose is squeezed out on a continuous, conveyor mesh or fabric filter with pressure rollers and then dried by passing an air-heating medium with a temperature of 100-115°C through a cellulose layer and a mesh to 5-10% humidity by high-speed impulse actions of vacuum followed by loosening of the packed cellulose.
• the obtained medical cotton wool is soft, satisfies the requirements of TU in terms of parameters, and has an increased wettability.
• Humidity is 8 %; degree of bleaching is 80%.
• the washed fiber is bleached with an alkaline-peroxide solution, the solution is separated, and the fiber is washed and subjected to squeezing out and drying on a continuous, conveyor-type mesh device with pressure rollers by passing an air heating medium with a temperature of 98°C and by high-speed impulse actions of vacuum through a fiber layer and a mesh. Drying fiber is proceeded up to 10% moisture, the loosened on a roller machine and then packed into bales.
• the degree of polymerization of linen fibers is - 10,000, the degree of polymerization of hemp is 8,000.
• the fiber Under laboratory conditions, after impregnating the fiber in a 3% melange solution, the fiber is disintegrated during hydrolysis in a solution medium at a temperature of 95-98°C at a modulus from 1:5 to 50-100 ⁇ m, the cellulose viscosity is reduced to 5-10 caps.
• the hydrolysis solution is also separated from the fiber. The hydrolysis solution is filtered out, lignin and impurities are precipitate, and after regeneration, the solution is recycled.
• Cellulose designed to manufacture NC for nitro-varnishes and enamels, is bleached in an aqueous alkaline-peroxide solution. The solution is filtered, regenerated and recycled. The bleached cellulose is washed, squeezes out and dried.
• Cellulose fibers are washed to a neutral medium, squeezed out in a centrifuge or screw-press at high-speed impulse actions of vacuum.
• cellulose is pressed through a heated conical press device with matrices and is squeezed out to a humidity of 15-20%.
• vacuum transport the cellulose as a dense layer enters a vacuum-impulse continuous dryer and is dried at a temperature of 110°C for 30 minutes to moisture content of not more than 10% and then is packaged.
• the cellulose is impregnated by high- speed impulse actions of vacuum in one or another solution and spreads onto fibers.
• Wood chips of a thickness 5 mm, width of 10 mm, and a length of 14 mm are impregnated under high-speed impulse actions of vacuum with a solution of sodium hydroxide and sodium sulphide at a concentration of 10 g/l at 95°C, module 1:7.5 with a pressure change of up to 10 mm Hg for 30 minutes. Further, the chips are disintegrated in an alkaline hydrolysis solution in a laboratory disintegrator to a particle size of 50-100 ⁇ m. Under high-speed impulse actions of vacuum at 95 °C, the hydrolysis of disintegrated chips in an alkaline medium is brought up to 10-15 cps for 1 hour.
• the hydrolysis solution with dissolved lignin and other impurities is filtered through woven metal meshes with mesh size of 50, 10, and 5 ⁇ m.
• the cellulose fiber is washed with water at a temperature of 60°C and water at a temperature of 20°C to obtain neutral medium.
• the washed cellulose is subjected to additional acid hydrolysis with a 3.0 % melange solution at 90-95°C using high-speed impulse actions of vacuum for 60 minutes to reduce the cellulose viscosity of 9-10 cPs.
• the hydrolysis solution is filtered.
• the fiber is washed, squeezed out in a laboratory centrifuge and dried to 8-10% moisture.
• cellulose for varnishes and enamels, it is bleached with a mixture of a solution of alkali (Noah) concentration of 4-5 g/liter and hydrogen peroxide of 10 g/liter at 70-75°C for 15 minutes, followed by filtration of the bleaching solution, washing, squeezing and drying at 115°C to a moisture content of 10% in cellulose.
• alkali Noah
• Alpha-cellulose content amounts to 96-97 %, wet ability is 150-160 g, humidity is 8-10%, viscosity is 6-9 caps, and degree of polymerization is 260.
• the wood chips are impregnated 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 impulse actions of vacuum with a pressure change up to 10 mm Hg for 30 minutes.
• the chips are disintegrated in a hydrolysis solution up to a particle size of 50-100 ⁇ m. Required viscosity of celluloses is achieved during the disintegration process.
• the required viscosity values are achieved by high-speed impulse actions of vacuum.
• the hydrolysis solution is filtered by a high-speed impulse actions of vacuum through a stainless mesh with cells of 10 and 5 ⁇ m, regenerated as per chemical composition with the organization of the solution circulation in a closed cycle way.
• 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. Washing water is filtered by high-speed impulse actions of vacuum through a stainless mesh with cell sizes of 10 and then 5 ⁇ m. Water is regenerated according to Ph with the organization of closed water circulation cycle.
• Washed cellulose is bleached with a mixture of aqueous solutions of 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 of washing water and organization of the solution and water recycling. Bleaching of cellulose is required only for the production of transparent nitrocellulose varnishes and enamels.
• the resulting cellulose is squeezed out in a centrifuge with the use of suction of water with high-speed impulse actions of vacuum. In a screw-press, the cellulose is pressed to a humidity of 15-20% through a heated conical press device with a cowl and then through the matrices. Drying of cellulose is carried out in a vacuum drier of continuous operation with the use of high-speed impulse actions of vacuum at a temperature of 110°C to a humidity of 10 %.
• the content in the cellulose produced of alpha cellulose is 96-97%, wettability is 150-160, viscosity is 5-9 cPs, humidity is 4-8%, and degree of polymerization is 220-240.
• the wood chips are impregnated with 8.0% nitric acid, without the use of a solution of Ca(HSO 3 ) 2 , without SO 2 , penetrating into the wood chips faster than the solution, and without the use of alcohols (butyl and others), and without the use of phenol, ethylene glycol and organic acids (acetic, monochloroacetic and other acids).
• the hydrolysis solution is separated in a centrifuge with the precipitation of dissolved impurities.
• the fiber is washed to a neutral medium, squeezed out in a centrifuge and dried to 10% moisture content.
• cellulose is bleached with NaOH solution in a mixture with hydrogen peroxide with separation, solution regeneration, washing and drying of cellulose up to 10% moisture content.
• Alpha-cellulose content reaches 97%, wettability is up to 150 g, degree of polymerization is 240, and humidity is 10%.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Wood Science & Technology (AREA)
• Paper (AREA)
• Polysaccharides And Polysaccharide Derivatives (AREA)

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• 2015
  • 2015-12-11 EP EP15857573.8A patent/EP3216917A4/fr not_active Withdrawn
  • 2015-12-11 KR KR1020177015098A patent/KR20180083251A/ko not_active Withdrawn
  • 2015-12-11 WO PCT/RU2015/000869 patent/WO2016072885A2/fr not_active Ceased
  • 2015-12-11 JP JP2017543700A patent/JP2017535690A/ja active Pending

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