WO2023005074A1

WO2023005074A1 - Method for producing powdered cellulose

Info

Publication number: WO2023005074A1
Application number: PCT/CN2021/132286
Authority: WO
Inventors: 沈云飞; 沈家源; 张依轩; 杨中伟; 褚祖礼
Original assignee: 湖州市菱湖新望化学有限公司
Priority date: 2021-07-27
Filing date: 2021-11-23
Publication date: 2023-02-02
Also published as: CN113417164A

Abstract

A method for producing powdered cellulose, which comprises following steps: S1, adding a low-concentration hydrochloric acid solution into wood pulp, and keeping the temperature at 60-80ºC for 1.5-2 hours to obtain a slurry material, wherein the mass concentration of the hydrochloric acid solution is 0.03-0.05%; S2, subjecting the slurry material to filter pressing, and collecting a filter cake; S3, drying the filter cake; and S4, crushing the dried filter cake to obtain powdered cellulose. The powdered cellulose is prepared by means of a production process of partial depolymerization of cellulose under the action of chemical energy and then crushing same by means of mechanical energy. The fibers are hydrolyzed by an inorganic acid with extremely low concentration, and the cellulose polymer is partially depolymerized by means of controlling a certain degree of polymerization. After the cellulose is partially depolymerized under the action of chemical energy, the molecular chain length is shortened under the action of the chemical energy, the strength of the cellulose is reduced, and the cellulose is more easily crushed by mechanical energy, such that the powdered cellulose with different grades of physical performance indexes is obtained.

Description

A kind of production method of powdery cellulose

technical field

The invention belongs to the field of polymer compound preparation, and relates to a method for preparing cellulose, in particular to a method for producing powdered cellulose.

Background technique

Cellulose is the oldest and most abundant natural polymer on the earth. It is inexhaustible and the most precious natural renewable resource for human beings. Cellulose is the most widely distributed and most abundant polysaccharide in nature, accounting for more than 50% of the carbon content in the plant kingdom. The cellulose content of cotton is close to 100%, making it the purest natural source of cellulose. In general wood, cellulose accounts for 40-50%, and there are 10-30% hemicellulose and 20-30% lignin. Cellulose is a substance that cannot be digested and absorbed by humans, but it plays an important role in ensuring human health and prolonging life. It is called the seventh nutrient.

Cellulose is a lumpy substance with poor fluidity and less exposure of surface hydroxyl groups, which is not conducive to its application. It is necessary to prepare cellulose from a lumpy form to a powder form to endow cellulose with new functions. Through technical research, powdered cellulose products of different shapes and types are produced, with different fineness, bulk specific gravity, fiber length, particle size and particle size, ranging from fine powder or firm particles with good fluidity to coarse and fluffy, It is imperative to meet the needs of cellulose in different application fields in a non-fluid form.

The microstructure of powdered cellulose is ribbon-like curved, uneven, porous, and flat at the intersections. It has good toughness, dispersibility and chemical stability, and strong water absorption capacity. Therefore, it is widely used in pharmaceuticals, food, cosmetics and industries. The field has a wide range of applications, and can be used in construction, electric power, oil processing, metallurgy, chemical fiber, printing and dyeing, filter materials, friction materials, gaskets, environmental protection, sewage treatment, seawater desalination, sulfonate refining, etc. Widely used in concrete, mortar, gypsum products, wood pulp sponge, asphalt roads and other fields, to prevent coating cracking, improve water retention, improve production stability and construction suitability, increase strength, and enhance surface adhesion Wait for good results.

technical problem

At present, the powdered cellulose developed in China is not as good as foreign products in terms of product color, average fiber length, water-soluble content, heavy metal content and other major indicators. Pharmaceutical grade, food grade and even industrial grade high-end powdered cellulose have high quality requirements. The powdered cellulose used in China is basically imported from Germany, the United States, Japan and other countries. Well-known foreign companies include Solvira Specialties Inc of the United States, Jeluwerk of Germany FMK Company and German JRS Ruidenmeier Cellulose Company, although the quality is better, but the price is high. There are almost no powdery cellulose production enterprises above designated size in my country.

The deep processing of lumpy cellulose started late in China, and only simple crushing is required. The product has a light bulk specific gravity, coarse particle size, and poor fluidity, so the scope of use is limited. At present, the main production process of research and production of powdered cellulose at home and abroad is to use mechanical pulverization, that is, to reduce the particle size of cellulose through mechanical pulverization, and convert the purified cellulose pulp into powdered cellulose. This process has obvious defects: due to the high connection strength between the fibers, multiple crushing and grinding are required in the preparation process, high mechanical energy consumption and high cost, and the particle size of the produced powdery cellulose is relatively coarse. Therefore, it is of great social and economic significance to solve the above technical difficulties simply and efficiently, to develop and research a new process for producing powdery cellulose, and to form industrialized production.

technical solution

In order to overcome the above-mentioned defects in the preparation of powdery cellulose in the prior art, the present invention provides a production method of powdery cellulose, and obtains powdery cellulose with all indicators meeting the powdery cellulose standard and better fluidity white.

The present invention adopts following technical scheme:

A method for producing powdery cellulose, comprising the steps of:

S1. Add low-concentration hydrochloric acid solution to the wood pulp, and keep it warm for 1.5 to 2 hours at a temperature of 60 to 80° C. to obtain a pulpy material; the mass concentration of the hydrochloric acid solution is 0.03 to 0.05%;

S2. Press-filter the slurry material to collect the filter cake;

S3. drying the filter cake;

S4. Pulverize the dried filter cake to obtain powdery cellulose.

The above technical solution adopts the production process of first partially depolymerizing cellulose through the action of chemical energy and then pulverizing it with mechanical energy to obtain powdery cellulose. The fiber is hydrolyzed with an extremely low concentration of inorganic acid, and the cellulose polymer is partially depolymerized by controlling a certain degree of polymerization. After the cellulose is partially degraded by the action of chemical energy, the length of the molecular chain is shortened by the action of chemical energy, the strength of the cellulose is reduced, and it is easier to be crushed by mechanical energy, so that powdered cellulose with different grades of physical properties can be prepared. The cellulose that is partially degraded by chemical energy is reduced in molecular chain length and fiber strength, and then it is mechanically pulverized, and it is easier to be pulverized by mechanical energy into finer-grained and better fluidity powdered cellulose.

In the prior art, acid hydrolysis is only used in the preparation of microcrystalline cellulose. According to the conventional understanding in the field, powdered cellulose cannot be obtained by acid hydrolysis, but microcrystalline cellulose with a lower degree of polymerization.

The invention breaks the inertial thinking, and controls the degree of polymerization of cellulose by adjusting the acid hydrolysis process conditions and using a very low concentration hydrochloric acid solution. Generally, the degree of polymerization ≥ 500 is powdery cellulose. If the acid concentration is too high, the temperature is too high, the hydrolysis speed is too fast, and the reaction process is difficult to control, resulting in excessive acid hydrolysis, which may degrade into microcrystalline cellulose and lose the characteristics of the target product powdery cellulose; if the acid concentration is too low, the temperature If it is too low and the reaction speed is too slow, the toughness of cellulose cannot be reduced and the subsequent mechanical crushing process will be affected. Process research Control the concentration of hydrochloric acid at 0.03-0.05%, and control the acid hydrolysis reaction temperature at 60-80°C for acid hydrolysis test, the best acid hydrolysis effect can be obtained.

Moreover, within this hydrochloric acid concentration, even if the acid hydrolysis time is too long, the cellulose will not be excessively acid hydrolyzed and become microcrystalline cellulose. The applicant has done related experiments. After acid hydrolysis for 2h, 4h, 6h, 8h, and 10h, the corresponding degrees of polymerization are 591, 573, 562, 550, and 541, which still meet the requirements for the degree of polymerization of powdered cellulose.

Preferably, after adding the hydrochloric acid solution, the solid content of the wood pulp is controlled to be 20 to 25%.

Preferably, the filter cake in step (S2) is washed to neutral with clean water.

Preferably, after the step (S1), the treatment is repeated once with a hydrochloric acid solution of the same concentration at a temperature of 20 to 40°C. The first acidolysis is carried out at a higher temperature, which is beneficial to the depolymerization of cellulose, and then repeat the acidolysis at a lower temperature. At this time, the molecular movement in the solution slows down, and the degree of polymerization of powdered cellulose does not meet the requirements. Cellulose with longer molecular chains continues to depolymerize, while cellulose that reaches the required degree of polymerization will not continue to be depolymerized into microcrystalline cellulose. Ensure that the degree of polymerization of powdered cellulose is still maintained under acid treatment conditions.

Preferably, after the acid hydrolysis, before the pressure filtration (that is, between step S1 and step S2), the pulpy material is subjected to beating treatment, so that it is easier to be pulverized, pulverized and ground into a finer particle size and a higher bulk specific gravity. Larger, better flowing powdered cellulose product. The principle of this method is that after the cellulose is partially degraded by the action of chemical energy, the length of the molecular chain is shortened by the action of chemical energy, and the strength of the cellulose is reduced. shaped cellulose.

Preferably, the pulverization in step (S4) is pulverized into powder by a special pulverizer for cellulose miniaturization through grinding, shearing and collision.

The pulverizer includes: a feeding part, a pulverizing part connected with the feeding part, a classification part connected with the pulverizing part, the feeding part is provided with a feeding port, and the classification part is provided with a discharge mouth.

Preferably, the feeding part includes a feeding bin, an outlet of the feeding bin communicates with the crushing part, and a horizontally arranged feeding wheel driven by a motor is arranged inside the feeding bin.

Preferably, the edges of the runner blades of the feed runner are provided with serrations.

Preferably, the outer ends of the runner blades of the feed runner have a conical structure.

Preferably, the crushing component includes a crushing box, a crushing structure arranged in the crushing box, the crushing structure includes a main shaft, an auxiliary shaft arranged around the main shaft, and a grinding wheel arranged on the auxiliary shaft, the main shaft is composed of The motor is driven to rotate, and the auxiliary shaft is driven to rotate by the main shaft.

Preferably, the gap between the grinding wheel and the inner wall of the crushing box is no more than 1.5 cm. In this way, a grinding zone is formed between the grinding wheel and the inner wall of the crushing box, and the materials in the grinding zone are fully ground during the continuous rotation of the grinding wheel.

Preferably, the grinding wheels are rotatably connected to the auxiliary shaft. When the main shaft rotates, the grinding wheels not only revolve around the main shaft, but also rotate around their respective auxiliary shafts. This process has grinding, shearing, collision The effect of improving the crushing effect of cellulose.

Preferably, blades are provided on the outer surface of the grinding wheel, and the blades are helically arranged along the axial direction of the grinding wheel.

Preferably, the upper end of the main shaft is provided with a rotor frame, and the auxiliary shaft is mounted on the rotor frame.

Preferably, a scraper structure is provided on the lower surface of the rotor frame, and the scraper structure includes a scraper shaft arranged on the rotor frame and a scraper arranged at the front end of the scraper shaft, and the scraper is located below the grinding wheel.

Preferably, the grading component includes a grading box arranged above the crushing box, a grading disk arranged in the grading box, an outlet connected with a suction device is arranged above the grading disk, and the crushing box There is also an air inlet.

As a preference, along the direction of the discharge port of the powdered cellulose, the fineness of the product is adjusted according to the rotating speed of the classifying disc, so that different types of powdered cellulose can be produced.

Through the centrifugal force of the grinding wheel, it continuously grinds, shears and collides with the pulverizer in a three-in-one movement, so that the cellulose is crushed and sheared in both horizontal and vertical directions to improve the crushing efficiency, which can make the fineness of powdered cellulose finer and the bulk specific gravity. Larger powders have better fluidity, and different types of products that can meet market demand can be produced by adjusting process parameters.

Beneficial effect

By implementing the above technical scheme, compared with the prior art, the present invention has the following advantages:

1. Adopt the production process of firstly depolymerizing the cellulose partially through the action of chemical energy and then pulverizing it with mechanical energy to obtain powdery cellulose. The fiber is hydrolyzed with an extremely low concentration of inorganic acid, and the cellulose polymer is partially depolymerized by controlling a certain degree of polymerization. After the cellulose is partially degraded by the action of chemical energy, the length of the molecular chain is shortened by the action of chemical energy, the strength of the cellulose is reduced, and it is easier to be crushed by mechanical energy to obtain powdered cellulose with different grades of physical properties.

2. Compared with pure mechanical crushing in the prior art, the manufacturing cost is lower.

3. The pulverizer in the present invention, through the centrifugal force of the grinding wheel, continues to grind, shear and collide with the pulverizer in a trinity movement, so that the cellulose is crushed and sheared in the horizontal and vertical directions to improve the pulverization efficiency, and the powdery fiber can be made The fineness of the powder is finer, the bulk specific gravity is larger, and the fluidity of the powder is better. By adjusting the process parameters, different models can be produced to meet the market demand.

Description of drawings

Accompanying drawing 1 is the structural representation of pulverizer shown in an embodiment of the present invention;

Accompanying drawing 2 is the structural representation of the feeding part of pulverizer shown in an embodiment of the present invention;

Accompanying drawing 3 is the structural representation of the feed runner of pulverizer shown in one embodiment of the present invention;

Accompanying drawing 4 is the structural representation of the runner blade of pulverizer shown in one embodiment of the present invention

Accompanying drawing 5 is the structural representation of the pulverizing part of pulverizer shown in one embodiment of the present invention;

Accompanying drawing 6 is the structure diagram of the classifying disk of the pulverizer shown in one embodiment of the present invention.

Embodiments of the present invention

The following clearly and completely describes the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1:

A kind of production method of powdery cellulose:

Raw materials: food grade wood pulp: α-cellulose content: 96.8%; ash content: 0.06%; loss on drying: 7.8%; degree of polymerization: 1073.

Hydrochloric acid: total acidity: 31%; reducing substances: <0.007%.

1. Add 1500kg of deionized water to the 2000L enamel reaction kettle, start the stirring paddle, slowly add 1.5kg of concentrated hydrochloric acid (mass fraction is about 31%), and make a 0.03% dilute hydrochloric acid solution. Slowly add 500kg of food-grade wood pulp into the 4000L new biaxial differential high-shear reaction device, turn on the steam heating switch of the spacer, and inject the prepared dilute hydrochloric acid solution at the same time. The wood pulp was swollen, mixed, and sheared and depolymerized in a new type of biaxial differential high-shear horizontal reactor to prepare a wood pulp mixture with a solid content of 24.8%, heated to 75°C, and kept for 2 hours for depolymerization.

2. Obtain the crude cellulose product after heat preservation and continuous depolymerization. Use a microscope to observe the water dispersion solution with a solid content of 1%. The cellulose depolymerizes from agglomerate to long fiber. The fiber length is obviously shortened, and the degree of polymerization is detected to be 589. .

3. After the depolymerization is completed, stop heating, stir to obtain a slurry material, add water to dilute the slurry material to a content of about 10%, and use a vertical three-stage high-speed high-shear cellulose refining disperser for beating treatment for 1 hour to obtain a slurry Put it into a plate and frame filter press for pressure filtration, rinse with deionized water until neutral, and obtain a crude cellulose product with a solid content of 45.8%, and a total of 986.2kg of filter cake wet material, with a yield of 97.98% (calculated as a dry product). The cellulose is dried by a high shear granulation drying device.

4. In the high-shear granulation drying device, the air inlet temperature is 150-200°C and the outlet air temperature is 70-80°C for drying.

5. Pulverization: The depolymerized cellulose is pulverized into powder through a combination of grinding, shearing and collision with a special pulverizer for cellulose miniaturization. After passing through a 60-mesh sieve, the powdered cellulose product has a weight loss on drying of 3.9%, the weight is 449.8kg, the yield is 95.7% (calculated as dry product), the bulk specific gravity is 0.26g/cm3, and the angle of repose is 47.1°.

Comparative material: Food additive powdered cellulose JustFiber BH200

JustFiber BH200 is a purified cellulose-containing plant fiber pulp obtained by processing α-cellulose. It has a large bulk density and good fluidity as a powdery cellulose. It is manufactured by Solvaira International Cellulose Corporation (IFC), North Tonawanda, New York, USA. Produced by Specialties Inc. It is used in the food industry as a dietary fiber, resists sticking or as a carrier material, and has a high chemical and microbiological purity. It is an ingredient that is odorless and tasteless and can effectively reduce the calorie content in food. It does not contain calories, fat, or digestible carbohydrates. It can be used in cheese, sausage casing bread, muffins, cakes, pasta, various sauces, tableted candy, as an anti-caking agent for cheese, as an excipient adsorbent for tableted candy, etc. Its bulk specific gravity is 0.25g/cm3, and its angle of repose is 49.2°.

Detect the physical property data of the powdery cellulose sample of above-mentioned embodiment 1, comparative example, contrast is as follows:

As can be seen from Table 1, the main physical performance indicators of the food additive powdery cellulose prepared by the present invention, the bulk specific gravity of Example 1 is slightly greater than that of U.S. JustFiber BH200, and the angle of repose is higher than that of U.S. JustFiber BH200. The BH200 is lower, indicating that the fluidity of the powder is better. The powdery cellulose produced by the present invention in Example 1 has all the detection indexes reaching or leading the international level, filling the blank of domestic products. By adjusting the process parameters, different models can be produced to meet the market demand.

Example 2

A kind of production method of powdery cellulose:

Raw materials: Industrial grade wood pulp: α-cellulose content: 88.13%; Ash content: 0.15%; Loss on drying: 7.9%; Polymerization degree: 1137.

Hydrochloric acid: total acidity: 31%; reducing substances: <0.007%.

1. Add 1500kg of deionized water into the 2000L enamel reaction kettle, start the stirring paddle, slowly add 2.5kg of concentrated hydrochloric acid (mass fraction is about 31%), and make a 0.05% dilute hydrochloric acid solution. Slowly add 500kg of industrial-grade wood pulp into a 4000L new biaxial differential high-shear reaction device, turn on the steam heating switch of the spacer, and inject the prepared dilute hydrochloric acid solution at the same time. Industrial-grade wood pulp was swollen, mixed, sheared and depolymerized in a new type of biaxial differential speed high-shear horizontal reactor to prepare a wood pulp mixture with a solid content of 24.5%, heated to 67°C, and kept warm for 1.5 hours for continuous depolymerization.

2. Obtain the crude cellulose product after heat preservation and continuous depolymerization. Use a microscope to observe the water dispersion solution with a solid content of 1%. The cellulose depolymerizes from agglomerate to long fiber. The fiber length is obviously shortened, and the degree of polymerization is detected to be 587.

3. After the depolymerization is completed, stop heating, stir to obtain a slurry material, add water to dilute the slurry material to a content of about 10%, and use a vertical three-stage high-speed high-shear cellulose refining disperser for beating for 2 hours to obtain a slurry Put it into a plate-and-frame filter press for pressure filtration, rinse with deionized water until neutral, and obtain a crude cellulose product with a solid content of 46.1%, and a filter cake wet material of 973.9kg, with a yield of 97.5% (calculated as a dry product). The cellulose is dried by a high shear granulation drying device.

5. Pulverization: The depolymerized cellulose is pulverized into powder through a combination of grinding, shearing and collision with a special pulverizer for cellulose miniaturization, and passes through a 400-mesh sieve. The powdered cellulose product has a loss on drying of 3.7%, a weight of 445.3kg, and a yield of 95.5% (calculated as a dry product). The laser particle size is D10=6.82μm, D50=16.19μm, D90=30.64μm, and passed through a 400-mesh sieve. Rate 100%.

Comparative material: Superfine coating additive powdered cellulose BE600-10TG

BE600-10TG is a powdered additive for chemical building material products made from wood pulp. It is a water-insoluble natural fiber with excellent flexibility, strength, dispersibility and chemical inertness. It is produced by JRS, the German Riddenmeier Cellulose Company. It is suitable for latex paint and dry powder coating. Adding 0.1-0.3% to the dry powder can increase the fiber and thicken the product; improve thixotropy and flow resistance to improve stability; enhance shrinkage and crack resistance; prolong operating time. Adding 0.5-3.0% to latex paint can enhance and improve the strength of latex paint; improve the stability and scrub resistance of latex paint, improve the water retention of latex paint, reduce the tension of paint film, and reduce cracking; improve operability and reduce rolling brush Splash phenomenon; reduce surface gloss. Its laser particle size is D10=6.9μm, D50=16.6μm, D90=34.22μm, and the passing rate of 400 mesh sieve is 99%.

Detect the physical property data of the powdery cellulose sample of above-mentioned embodiment 2, comparative example, contrast is as follows:

As can be seen from Table 2, the coating additive powdery cellulose main physical performance index prepared by the present invention, embodiment 2 laser particle size distribution is slightly finer than Germany BE600-10TG, 400 mesh sieve fineness and Germany BE600-10TG near. The powdery cellulose produced by the present invention in Example 2 has all the detection indexes reaching or leading the international level, filling the blank of domestic products. By adjusting the process parameters, different models can be produced to meet the market demand.

Comparing the national standards of food additives and the physical and chemical indicators of the Chinese Pharmacopoeia, the powdery cellulose prepared by the present invention all meet the following standards.

The special pulverizer for cellulose miniaturization used in the examples has a structure as shown in Figure 1, including a feeding part 01, a pulverizing part 02 connected with the feeding part 01, and a pulverizing part connected with the pulverizing part 02. A grading component 03, the feeding component 01 is provided with an inlet A, and the grading component 03 is provided with an outlet B.

The feeding part 01, as shown in accompanying drawing 2, includes a feeding bin 11, the outlet of the feeding bin 11 is connected to the pulverizing part 02, and the feeding bin 11 is provided with a lateral arrangement driven by a motor to rotate. The feeding runner 12, as shown in accompanying drawing 3. Because the material is fibrous, the conventional blade structure is easy to cause jamming, so the outer end of the runner blade 121 of the feed runner 12 is set in a tapered structure, and the edge is provided with sawtooth, as shown in Figures 3 and 4 , in order to reduce the resistance of cellulose, which can effectively solve the problem of motor damage caused by blade jamming and shutdown.

The crushing component 02 includes a crushing box 21, a crushing structure arranged in the crushing box 21, the crushing structure includes a main shaft 22, an auxiliary shaft 23 arranged around the main shaft 22, and a grinding wheel 24 arranged on the auxiliary shaft 23 , the outer surface of the grinding wheel 24 is provided with blades, and the blades are helically arranged along the axial direction of the grinding wheel 24 . The main shaft 22 is driven to rotate by the motor 04, and the upper end of the main shaft 22 is provided with a rotor frame 25, and the auxiliary shaft 23 is mounted on the rotor frame 25 to drive the rotor frame 25 to rotate, and the auxiliary shaft 23 also rotates thereupon. The gap between the grinding wheel 24 and the inner wall of the crushing box 21 is no more than 1.5 cm. In this way, a grinding zone is formed between the grinding wheel 24 and the inner wall of the crushing box 21, and the materials in the grinding zone are fully ground during the continuous rotation of the grinding wheel 24. The grinding wheel 24 is rotatably connected to the auxiliary shaft 23. When the main shaft 22 rotates, the grinding wheel 24 not only revolves around the main shaft 22, but also rotates around the respective auxiliary shaft 23. This process has grinding, shearing, The effect of collision improves the crushing effect of cellulose. The lower surface of the rotor frame 25 is provided with a scraper structure, the scraper structure includes a scraper shaft arranged on the rotor frame 25 and a scraper arranged at the front end of the scraper shaft, the scraper is located below the grinding wheel 24, During the synchronous rotation of the scraper and the grinding wheel 24, the material is scraped and thrown into the grinding area formed by the grinding wheel 24 and the inner wall of the box to form a pad layer. The material is crushed, that is, the effect of cellulose micronization is achieved.

The grinding wheel 24 produces a strong centrifugal force during the revolution and self-propagation, and has a strong roller grinding effect with the stator. Driven by the centrifugal force and the rotating force field of the grinding wheel 24, the crushed materials enter the grinding area formed by the grinding wheel 24 and the stator. The material is crushed under the action of strong extrusion force and grinding force. It is also possible to adjust the clearance of the spiral knife on the grinding wheel 24 according to the fineness of the product, so as to produce different types of powdered cellulose products.

The grading unit 03 includes a grading box 31 arranged above the crushing box 21, a grading disk 32 arranged in the grading box 31, a discharge port B connected with a suction device is arranged above the grading disk 32, The crushing box 21 is also provided with an air inlet. The structure of the classifying disc 32 is shown in Figure 6, and the fineness of the product can be adjusted according to the rotating speed of the classifying disc 32, so that different types of powdered cellulose can be produced.

Claims

A kind of production method of powdery cellulose is characterized in that, comprises the steps:

S1. Add low-concentration hydrochloric acid solution to the wood pulp, and keep it warm for 1.5 to 2 hours at a temperature of 60 to 80° C. to obtain a pulpy material; the mass concentration of the hydrochloric acid solution is 0.03 to 0.05%;

S2. Press-filter the slurry material to collect the filter cake;

S3. drying the filter cake;

S4. Pulverize the dried filter cake to obtain powdered cellulose.
The production method of a kind of powdered cellulose according to claim 1, characterized in that, after adding the hydrochloric acid solution, the solid content of the wood pulp is controlled to be 20 to 25%.
The production method of powdery cellulose according to claim 1, characterized in that the filter cake in step (S2) is washed to neutral with clean water.
The production method of powdered cellulose according to claim 1, characterized in that, after step (S1), the same concentration of hydrochloric acid solution is used to repeat the treatment once, and the temperature is 20 to 40°C.
The production method of powdery cellulose according to claim 1, characterized in that, the pulverization in step (S4) adopts a special pulverizer for cellulose micronization, and the pulverizer includes: a feeding part, and the feeding part A crushing part connected with the material part, a classification part connected with the crushing part, the feeding part is provided with a feeding port, and the classifying part is provided with a discharge port; the feeding part includes a feeding bin, the The outlet of the feeding bin is connected to the crushing part, and a horizontally arranged feeding runner driven by a motor is arranged in the feeding bin.
The method for producing powdered cellulose according to claim 5, wherein the edge of the runner blade of the feed runner is provided with sawtooth.
A method for producing powdery cellulose according to claim 5 or 6, characterized in that the outer end of the runner blade of the feed runner is in a conical structure.
A method for producing powdered cellulose according to claim 5, wherein the crushing component comprises a crushing box and a crushing structure arranged in the crushing box, the crushing structure includes a main shaft, and is arranged around the main shaft. The auxiliary shaft and the grinding wheel arranged on the auxiliary shaft, the main shaft is driven to rotate by the motor, and the auxiliary shaft is driven to rotate by the main shaft.
A method for producing powdery cellulose according to claim 8, characterized in that the gap between the grinding wheel and the inner wall of the crushing box is no more than 1.5 cm.
A method for producing powdery cellulose according to claim 8, wherein the grading components include a grading box arranged above the crushing box, a grading disc arranged in the grading box, and the A discharge port connected with a suction device is arranged above the classifying disc, and an air inlet is also arranged on the crushing box.