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WO-2026092303-A1 - METHOD FOR LARGE-SCALE PREPARATION OF CELLULOSE NANOCRYSTALS WITH HIGH YIELD, AND PRODUCT THEREOF

WO2026092303A1WO 2026092303 A1WO2026092303 A1WO 2026092303A1WO-2026092303-A1

Abstract

Provided in the present invention are a novel method for preparing cellulose nanocrystals (CNCs) and a product thereof, belonging to the technical field of novel manufacturing. The method of the present invention comprises co-milling a cellulose raw material and a selective water-soluble molecule to form specific composite micelles, and then performing subsequent degradation and stripping and/or phase separation on the composite micelles to obtain cellulose nanocrystals. The cellulose nanocrystals (CNCs) are produced in a large scale with an extremely low amount of dilute acids, an ultra-high yield, extremely low environmental impact and low costs.

Inventors

  • TAN, ZHENG
  • LIU, XIAOWEN

Assignees

  • 牡丹江霖润药用辅料有限责任公司
  • 北京臻博科技创新有限公司

Dates

Publication Date
20260507
Application Date
20251023
Priority Date
20241029

Claims (10)

  1. A method for producing cellulose nanocrystals, characterized by comprising the step of preparing a cellulose micelle dispersion in water, comprising more than 50% by weight of cellulose micelles with a particle size of less than 1000 nanometers, using cellulose raw materials and selectively water-soluble molecules; preferably, more than 70% by weight of cellulose micelles with a particle size of less than 1000 nanometers; preferably, more than 90% by weight of cellulose micelles with a particle size of less than 1000 nanometers; preferably, more than 97% by weight of cellulose micelles with a particle size of less than 1000 nanometers.
  2. According to the method of claim 1, the cellulose raw material is hydrolyzed cellulose or commercially available cellulose.
  3. According to the method of claim 2, the degree of polymerization of the hydrolyzed cellulose is controlled at 50-300 glucose units, preferably 100-250 glucose units.
  4. According to the method of claims 2-3, the hydrolyzed cellulose is obtained by low-acid hydrolysis of plant cellulose from any source; preferably, hydrolyzed cellulose is prepared by dilute inorganic acid hydrolysis; preferably, the acid concentration is 0.1%-10%; preferably, it is dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, etc. with a concentration of 0.1%-1%.
  5. According to the method of claim 2, the commercially available cellulose is selected from microcrystalline cellulose plus sodium carboxymethyl cellulose composite colloid, microcrystalline cellulose plus xanthan gum composite colloid, microcrystalline cellulose plus sodium alginate composite colloid, microcrystalline cellulose plus carrageenan composite colloid, microcrystalline cellulose plus pectin composite colloid, microcrystalline cellulose plus guar gum composite colloid, microcrystalline cellulose plus modified starch composite colloid, etc.
  6. According to the method described in claims 1-5, the selectively water-soluble molecules are selected from: carboxymethyl cellulose and its salts; water-soluble cellulose ethers such as hydroxypropyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, etc.; natural water-soluble colloid molecules such as starch, sodium alginate, pectin, carrageenan, xanthan gum, chitosan, water-soluble plant protein, water-soluble animal protein, etc.; synthetic polymers such as polyvinyl alcohol, polyethylene glycol, povidone (polyvinylpyrrolidone), copovidone, poloxamer (polyoxyethylene polyoxypropylene ether block copolymer), carbomer (polyacrylic acid), polyacrylamide, polyethyleneimine, polyethyleneamine, etc.; water-soluble salts such as sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, aluminum chloride, ammonium chloride, zinc chloride, ferric chloride, copper chloride, zirconium chloride, sodium carbonate, zirconium carbonate, magnesium sulfate, aluminum sulfate, copper sulfate, ferric sulfate, zirconium sulfate, organic quaternary ammonium salts, etc.; and water molecules themselves such as liquid water and solid ice.
  7. The method according to claims 1-6 includes the following steps: (1) The cellulose micelle dispersion is prepared by co-milling and/or forcefully shearing cellulose raw materials and selective water-soluble molecules; (2) Remove particles with a particle size greater than and/or equal to 1000 nm from the cellulose micelle dispersion prepared in step (1) by centrifugation or filtration to obtain a centrifuged supernatant or filtrate with a particle size less than 1000 nm. (3) The supernatant or filtrate obtained in step (2) is degraded and exfoliated to obtain a suspension of hydrolyzed cellulose nanoparticles; preferably, the degradation and exfoliation is carried out by an oxidation reaction using hydrogen peroxide; (4) The hydrolyzed cellulose nanoparticle suspension obtained in step (3) is centrifuged or filtered to obtain a concentrated solution or wet cake of cellulose nanocrystals, thus obtaining the cellulose nanocrystal product.
  8. The method according to claims 1-6 includes the following steps: (1) The cellulose micelle dispersion is prepared by co-milling and/or forcefully shearing cellulose raw materials and selective water-soluble molecules; (2) Remove particles with a particle size greater than and/or equal to 1000 nm from the cellulose micelle dispersion prepared in step (1) by centrifugation or filtration to obtain a centrifuged supernatant or filtrate with a particle size less than 1000 nm. (3) The centrifuged supernatant or filtrate obtained in step (2) is concentrated or dried to obtain a composite cellulose nanocrystal product containing selective water-soluble molecules.
  9. The method according to claims 1-6 includes the following steps: (1) The cellulose micelle dispersion is prepared by co-milling and/or forcefully shearing cellulose raw materials and selective water-soluble molecules; (2) The cellulose micelle dispersion obtained in step (1) is degraded and exfoliated to obtain a suspension of hydrolyzed cellulose nanoparticles; preferably, the degradation and exfoliation are selected from any one or a combination of oxidation, enzymatic hydrolysis, acid degradation, alkaline degradation, microbial degradation, and ultra-strong shear mechanical degradation; more preferably, the degradation and exfoliation are carried out by oxidation reaction using hydrogen peroxide; (3) The hydrolyzed cellulose nanoparticle suspension obtained in step (2) is centrifuged or filtered to obtain a concentrated solution or wet cake of cellulose nanocrystals, thus obtaining the cellulose nanocrystal product.
  10. The method according to claims 1-6 includes the following steps: (1) The cellulose raw material is co-milled and/or subjected to strong shearing with water molecules or water-soluble salts to prepare the cellulose micelle dispersion; (2) The cellulose micelle dispersion obtained in step (1) is degraded and exfoliated to obtain a suspension of hydrolyzed cellulose nanoparticles; preferably, the degradation and exfoliation are selected from any one or a combination of oxidation, enzymatic hydrolysis, acid degradation, alkaline degradation, microbial degradation, and ultra-strong shear mechanical degradation; more preferably, the degradation and exfoliation are performed using an ultra-strong shear mechanical degradation and exfoliation method; most preferably, the degradation and exfoliation are performed using high-pressure homogenization; (3) Centrifuge or filter the hydrolyzed cellulose nanoparticle suspension obtained in step (2) to obtain a concentrated solution or wet cake of cellulose nanocrystals, and obtain cellulose nanocrystal products.

Description

A method and product for high-yield, large-scale preparation of cellulose nanocrystals Technical Field This invention provides a method for producing cellulose nanocrystals, achieving high yield and large-scale production of cellulose nanocrystal products. It belongs to the field of novel manufacturing technology. Background Technology Nanocellulose is an emerging nanomaterial prepared from cellulose raw materials, with diameters in the nanometer range and lengths in the micrometer or nanometer range. It mainly includes cellulose nanofibers (CNF), cellulose nanocrystals (CNC), and bacterial nanocellulose (BNC). Nanocellulose possesses excellent properties, such as a specific aspect ratio, large specific surface area, ultra-high mechanical strength, excellent biocompatibility, rheological properties, chemical amphiphilicity, optical and dielectric properties, etc. Nanocellulose can be obtained from various sources, such as wood, bagasse, cotton, waste paper, hemp, rice husks, straw, algae, bamboo, reeds, fruits and vegetables, and agricultural waste. It has wide applications in various industrial fields, food and nutrition, medicine, biomedical materials, daily chemical and cosmetic products, chemical industry, high-end coatings, aerospace, automotive and shipbuilding, new energy materials, building materials, packaging materials, image display and printing, 3D printing, aerogels, agricultural materials, optical materials, electronic materials, and many other industries. Cellulose cellulose (CNC) molecules range in diameter from 5-50 nm, typically 5-30 nm, and in length from 20-900 nm, exhibiting rod-like or needle-like morphology. Current CNC preparation methods primarily utilize strong acid hydrolysis, such as with 60%-74% sulfuric acid. The waste acid and wastewater generated during this process pose significant environmental challenges. Furthermore, the concentrated acid hydrolysis and purification processes impose extremely stringent safety and cost requirements on equipment and processes. A major problem is the extremely low yield of cellulose CNCs produced, approximately only 15%-30%. All these factors have prevented large-scale, economical, and commercial production of cellulose CNCs globally for a long time. Another challenge brought by strong acid hydrolysis, such as with concentrated sulfuric acid or concentrated nitric acid, is the partial substitution of hydroxyl groups on the cellulose CNC molecules by strong acid groups, leading to potential biotoxicity and health risks. Therefore, existing technologies have not yet enabled the large-scale, economical, and commercial production of cellulose nanocrystals (CNC). Summary of the Invention This invention provides a novel method for preparing cellulose nanocrystals (CNCs) with extremely low dilute acid usage, ultra-high yield, and extremely low environmental impact, thereby truly achieving low-cost, large-scale industrial production of cellulose nanocrystals (CNCs). This invention is achieved through the following technical solution: The invention provides a method for producing cellulose nanocrystals, characterized by the step of preparing a specific cellulose micelle dispersion from cellulose raw materials and selectively water-soluble molecules, wherein the specific cellulose micelles are 50% or more by weight of cellulose micelles in water with a particle size of less than 1000 nanometers; preferably, 70% or more by weight of cellulose micelles in water with a particle size of less than 1000 nanometers; preferably, 90% or more by weight of cellulose micelles in water with a particle size of less than 1000 nanometers; preferably, 97% or more by weight of cellulose micelles in water with a particle size of less than 1000 nanometers. Preferably, in the method described above, the cellulose raw material is hydrolyzed cellulose or commercially available cellulose. Preferably, in the method described above, the degree of polymerization of the hydrolyzed cellulose is controlled at 50-300 glucose units, more preferably 100-250 glucose units. Preferably, in the method described above, the hydrolyzed cellulose is obtained from plant cellulose of any source through low-acid hydrolysis; preferably, hydrolyzed cellulose is prepared using a diluted inorganic acid hydrolysis method; preferably, the acid concentration is 0.1%-10%; more preferably, it is a 0.1%-1% concentration of dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, etc. Preferably, in the method described above, the commercially available cellulose is selected from microcrystalline cellulose plus sodium carboxymethyl cellulose composite colloid, microcrystalline cellulose plus xanthan gum composite colloid, microcrystalline cellulose plus sodium alginate composite colloid, microcrystalline cellulose plus carrageenan composite colloid, microcrystalline cellulose plus pectin composite colloid, microcrystalline cellulose plus guar gum composite colloid, microcrystalline cellulose pl