A highly substituted cationic cellulose dispersion and its preparation method

Abstract

This application discloses a highly substituted cationic cellulose dispersion and its preparation method, relating to the field of cellulose modification technology. The preparation method includes the following steps: adding an alkaline solution to wood pulp, stirring until uniform and semi-dry, thus alkalizing the wood pulp; adding a cationic modifier and an organic solvent to the alkalized wood pulp, subjecting it to high-speed shear dispersion, and then conducting a constant-temperature reaction; after the constant-temperature reaction, neutralizing the product with acid, and obtaining modified cellulose after washing and drying; taking the above modified cellulose, adding water, subjecting it to high-speed shear dispersion, filtering, and obtaining the highly substituted cationic cellulose dispersion. The preparation method of this application is simple and low-energy-consuming, and the prepared cellulose dispersion has the advantages of high cationic substitution degree, high Zeta potential, and stable dispersion.

Description

Technical Field

[0001] This application relates to the field of cellulose modification technology, and more specifically, to a highly substituted cationic cellulose dispersion and its preparation method. Background Technology

[0002] The surface of natural wood pulp cellulose molecules is rich in hydroxyl groups, and the strong intramolecular and intermolecular hydrogen bonding results in a negatively charged surface, excessive hydrophilicity, poor compatibility with synthetic polymers, and weak adsorption capacity for anionic substances, which severely limits its application in textile sizing, paper strengthening agents, water treatment flocculants, and bio-based functional materials.

[0003] Existing cationic cellulose modification technologies mostly focus on the etherification reaction of cellulose powder, which has the following drawbacks: 1. The high crystallinity of wood pulp fibers and insufficient alkalization activation result in low cationic substitution degree (usually <0.6), which cannot meet the application requirements of high charge density; 2. Modified cellulose particles have poor dispersibility, low Zeta potential (usually < +20mV), and the dispersion is prone to agglomeration and precipitation, resulting in insufficient stability. 3. Wood pulp alkalization often uses high temperature (>40℃) or low temperature (<10℃) conditions. However, high temperature will cause excessive swelling of cellulose and degradation of molecular chains, while low temperature will cause insufficient alkali penetration and uneven activation of hydroxyl groups, ultimately resulting in low cationic substitution degree and poor dispersion stability.

[0004] In summary, developing a method for preparing cationic cellulose dispersions that can achieve high degree of substitution, high dispersion stability, and high zeta potential has become a pressing technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this application is to provide a method for preparing a highly substituted cationic cellulose dispersion, thereby improving the dispersion stability and zeta potential of wood pulp in water.

[0006] Another objective of this application is to provide a highly substituted cationic cellulose dispersion prepared by the above method.

[0007] To solve the above-mentioned technical problems, the technical solution adopted in this application is as follows: On the one hand, this application provides a method for preparing a highly substituted cationic cellulose dispersion, comprising the following steps: S1. Add an alkaline solution to the wood pulp and stir well to alkalize the wood pulp; S2. Add cationic modifier and organic solvent to the alkalized wood pulp, perform high-speed shear dispersion, and then carry out a constant-temperature reaction; S3. After the isothermal reaction is completed, the product is neutralized with acid, and then the modified cellulose is obtained after washing and drying. S4. Take the above modified cellulose, add water, disperse by high-speed shearing, and filter to obtain the highly substituted cationic cellulose dispersion.

[0008] On the other hand, this application provides a highly substituted cationic cellulose dispersion prepared by the above method.

[0009] Compared with the prior art, the embodiments of this application have at least the following advantages or beneficial effects: 1. High degree of substitution and high zeta potential: This application achieves full activation of wood pulp fibers and uniform grafting of modifiers through semi-dry room temperature alkalization combined with high-speed shear dispersion. The degree of substitution of modified cellulose can reach 0.6-0.7, and the zeta potential is increased to +26mV to +35mV, which significantly enhances the adsorption capacity for anionic substances.

[0010] 2. Excellent dispersion stability: In the dispersion step, this application uses a high-speed shearing process to refine the modified cellulose particles to the nanoscale. Combined with the electrostatic repulsion of cationic groups, the dispersion can be stably dispersed in water for more than 72 hours without obvious precipitation.

[0011] 3. Low energy consumption: This application adopts room temperature alkalization, which does not require additional heating or cooling equipment. It can be directly connected with the subsequent 60℃ modification process, simplifying the temperature control process and reducing energy consumption by 15%-20%. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 Photos of the dispersions of Examples 1-4 (cf) after 0 (cf), 2 (c2-f2) hours, and 30 days (c3-f3); Figure 2 Photographs of the dispersions of Comparative Examples 1 and 3 (a and b) after 0 (a and b), 2 (a2 and b2) hours, and 6 (a3 and b3) hours. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0015] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present application will now be described in detail with reference to specific embodiments.

[0016] A method for preparing a highly substituted cationic cellulose dispersion includes the following steps: S1. Add an alkaline solution to the wood pulp and stir well to alkalize the wood pulp; S2. Add cationic modifier and organic solvent to the alkalized wood pulp, perform high-speed shear dispersion, and then carry out a constant-temperature reaction; the organic solvent is used as a swelling agent, dispersant, and reaction medium regulator in this application, and through the synergistic effect of physical and chemical processes, avoids the problems of natural wood pulp fibers being difficult to penetrate, easy to agglomerate, and uneven distribution of modifier; S3. After the isothermal reaction is completed, the product is neutralized with acid, and then the modified cellulose is obtained after washing and drying. S4. Take the above modified cellulose, add water, disperse by high-speed shearing, and filter to obtain the highly substituted cationic cellulose dispersion.

[0017] One of the core aspects of this application lies in the room-temperature alkalization in step S1, which is based on the following core mechanism: A. Moderate swelling and structural preservation: At room temperature, NaOH solution can uniformly penetrate the amorphous region of wood pulp fiber, moderately activating the hydroxyl groups, while avoiding excessive swelling and disintegration of the crystalline region caused by high temperature, thus maintaining the integrity of the fiber structure. B. Inhibition of alkaline degradation: The rates of cellulose's "peeling reaction" and "alkaline hydrolysis" increase exponentially with increasing temperature. At room temperature, the glycosidic bond breaking can be significantly slowed down, preserving the high molecular weight and high degree of polymerization of cellulose, providing a structural basis for the stability of the subsequent dispersion. C. Uniform activation guarantee: In the semi-dry state, the diffusion rate of alkaline solution at room temperature is slow, which can fully activate the hydroxyl groups on the fiber surface and inside, avoiding the uneven problem of "surface activation and internal inactivation" at low temperature, and laying the foundation for uniform grafting of cationic modifiers.

[0018] In some embodiments of this application, the alkaline solution in step S1 above is prepared by dissolving sodium hydroxide in 3-6 times its mass of deionized water; the mass ratio of the wood pulp to sodium hydroxide is 1:(0.5-1).

[0019] In some embodiments of this application, the alkalization temperature in step S1 is 25-30°C and the alkalization time is 0.5-2 hours.

[0020] In some embodiments of this application, the organic solvent in step S2 above includes one or more of isopropanol, ethanol, tetrahydrofuran, DMAC, and DMSO.

[0021] In some embodiments of this application, the cationic modifier in step S2 is one or more of 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTMAC), glycidyltrimethylammonium chloride (GTA), 2,3-epoxypropyltriethylammonium chloride (GTEAC), and 3-chloro-2-hydroxypropyltriethylammonium chloride (CHPTEAC).

[0022] In some embodiments of this application, the ratio of the amount of cationic modifier and organic solvent added in step S2 to the wood pulp in step S1 is 2-6g: 2-6mL: 1g; the constant temperature reaction temperature is 50-70℃, and the time is 4-8h.

[0023] In some embodiments of this application, the acid solution in step S3 above is a dilute hydrochloric acid solution with a concentration of 0.5-2 mol / L, and the pH range after neutralization is 6-7; the cleaning is washing three times with deionized water and anhydrous ethanol in sequence; the drying temperature is 70-100℃, and the drying time is 4-24h.

[0024] In some embodiments of this application, the high-speed shearing in step S2 above is performed using one or more combinations of a high-speed disperser, a high-shear emulsifier, a colloid mill, and mechanical stirring. When the equipment is a high-speed disperser, the zirconium bead particle size is 0.5-2 mm, and the equipment rotation speed is 500-1000 rpm. When the equipment is a high-shear emulsifier, the rotor rotation speed is 10000-20000 rpm, and the processing time is 1-3 hours. When the equipment is a colloid mill, the grinding disc gap is 5-50 μm, the rotation speed is 3000-8000 rpm, and the processing time is 1-2 hours. When the equipment is mechanical stirring, the stirring speed is 300-500 rpm, and the processing time is 1-3 hours.

[0025] In some embodiments of this application, the high-speed shearing in step S4 uses one or more combinations of a high-speed disperser, a high-shear emulsifier, a sand mill, a bead mill, a colloid mill, and a high-pressure homogenizer. When the equipment is a high-speed disperser, a sand mill, or a bead mill, the zirconium bead particle size is 0.5-2 mm, the equipment linear speed is 8-15 m / s, and the processing time is 1-3 h. When the equipment is a high-shear emulsifier, the rotor speed is 10000-20000 rpm, and the processing time is 1-2 h. When the equipment is a high-pressure homogenizer, the working pressure is 50-150 MPa, and the number of homogenization cycles is 3-5. When the equipment is a colloid mill, the grinding disc gap is 5-50 μm, the rotation speed is 3000-8000 rpm, and the processing time is 1-2 h.

[0026] A highly substituted cationic cellulose dispersion was prepared using the method described above.

[0027] The features and performance of this application will be further described in detail below with reference to the embodiments. Example 1

[0028] S1. Take 10g of wood pulp, add 10g of NaOH and 30g of deionized water, stir until semi-dry, and alkalize at 25℃ for 1 hour; S2. Add 40g of 2,3-epoxypropyltriethylammonium chloride (GTEAC), 60mL of isopropanol and an appropriate amount of zirconium beads with a particle size of 1mm to the above product. Disperse the product using a high-speed disperser (1500rpm, 12m / s linear velocity) for 2h, and then place it in a 60℃ constant temperature water bath for 6h. S3. Neutralize with 1 mol / L dilute HCl to pH=6.5, wash three times with deionized water and anhydrous ethanol, and dry at 80℃ for 12h to obtain modified cellulose; S4. Take 5g of modified cellulose, add 75g of deionized water, disperse using a high-speed disperser (1200rpm) for 2 hours, and filter to obtain the dispersion. Example 2

[0029] S1. Take 10g of wood pulp, add 10g of NaOH and 30g of deionized water, stir until semi-dry, and alkalize at 25℃ for 1 hour; S2. Add 40g of 2,3-epoxypropyltriethylammonium chloride (GTEAC), 60mL of isopropanol, 0.5g of triethylamine and an appropriate amount of zirconium beads with a particle size of 1mm to the above product. Disperse the product using a high-speed disperser (1500rpm, 12m / s linear velocity) for 2h, and then place it in a 60℃ constant temperature water bath for 6h. S3. Neutralize with 1 mol / L dilute HCl to pH=6.5, wash three times with deionized water and anhydrous ethanol, and dry at 80℃ for 12h to obtain modified cellulose; S4. Take 5g of modified cellulose, add 75g of deionized water, disperse using a high-speed disperser (1200rpm) for 2 hours, and filter to obtain the dispersion. Example 3

[0030] S1. Take 10g of wood pulp, add 10g of NaOH and 30g of deionized water, stir until semi-dry, and alkalize at 25℃ for 1 hour; S2. Add 40g of 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTMAC) and 60mL of ethanol to the above product, disperse it using a high-speed disperser (1500rpm, 12m / s) for 2h, and then place it in a 60℃ constant temperature water bath for 6h. S3. Neutralize with 1 mol / L dilute HCl to pH=6.5, wash three times with deionized water and anhydrous ethanol, and dry at 80℃ for 12h to obtain modified cellulose; S4. Take 5g of modified cellulose, add 75g of deionized water, disperse using a high-speed disperser (1200rpm) for 2 hours, and filter to obtain the dispersion. Example 4

[0031] S1. Take 10g of wood pulp, add 10g of NaOH and 30g of deionized water, stir until semi-dry, and alkalize at 25℃ for 1 hour; S2. Add 40g glycidyltrimethylammonium chloride (GTA) and 60mL deionized water to the above product, disperse it using a high-speed disperser (1500rpm, 12m / s linear velocity) for 2h, and then place it in a 40℃ constant temperature water bath for 6h. S3. Neutralize with 1 mol / L dilute HCl to pH=6.5, wash three times with deionized water and anhydrous ethanol, and dry at 80℃ for 12h to obtain modified cellulose; S4. Take 5g of modified cellulose, add 75g of deionized water, disperse using a high-speed disperser (1200rpm) for 2 hours, and filter to obtain the dispersion.

[0032] Comparative Example 1

[0033] The difference between this comparative example and Example 1 is that the alkalized wood pulp is not cationic modified. The specific steps are as follows: S1. Take 10g of wood pulp, add 10g of NaOH and 30g of deionized water, stir until semi-dry, and alkalize at 25℃ for 1 hour; S2. Neutralize with 1 mol / L dilute HCl to pH=6.5, wash three times with deionized water and anhydrous ethanol, and dry at 80℃ for 12h to obtain modified cellulose; S3. Take 5g of alkalized cellulose, add 75g of deionized water, disperse using a high-speed disperser (1200rpm) for 2 hours, and filter to obtain the dispersion.

[0034] Comparative Example 2

[0035] The difference between this comparative example and Example 1 is that isopropanol is not added. The specific steps are as follows: S1. Take 10g of wood pulp, add 10g of NaOH and 30g of deionized water, stir until semi-dry, and alkalize at 25℃ for 1 hour; S2. Add 40g of 2,3-epoxypropyltriethylammonium chloride (GTEAC), 60mL of deionized water, and an appropriate amount of zirconium beads with a particle size of 1mm to the above product. Disperse the product using a high-speed disperser (1500rpm, 12m / s linear velocity) for 2h, and then place it in a 60℃ constant temperature water bath for 6h. S3. Neutralize with 1 mol / L dilute HCl to pH=6.5, wash three times with deionized water and anhydrous ethanol, and dry at 80℃ for 12h to obtain modified cellulose; S4. Take 5g of modified cellulose, add 75g of deionized water, disperse using a high-speed disperser (1200rpm) for 2 hours, and filter to obtain the dispersion.

[0036] Comparative Example 3

[0037] The difference between this comparative example and Example 1 is the use of conventional low-temperature alkalization. The specific steps are as follows: S1. Take 10g of wood pulp, add 11.25g of NaOH and 138.75g of deionized water, alkalize at 4℃ for 2h, and filter to obtain alkalized cellulose; S2. The molar ratio of glycidyltrimethylammonium chloride to γ-aminopropyltriethoxysilane is 1:1.1, and the reaction is carried out at 80℃ for 4 hours to obtain silane-modified glycidyltrimethylammonium chloride. S3. The alkalized cellulose obtained from S1 and S2 and silane-modified glycidyltrimethylammonium chloride were reacted at a molar ratio of 0.8:1 with cellulose glucose units. The pH was adjusted to 11.5, the reaction temperature was 60℃, and the reaction time was 3h. S4. Neutralize with 1 mol / L dilute HCl to pH=6.5, wash three times with deionized water and anhydrous ethanol, and dry at 80℃ for 12h to obtain modified cellulose; S5. Take 5g of modified cellulose, add 75g of deionized water, disperse using a high-speed disperser (1200rpm) for 2 hours, and filter to obtain the dispersion.

[0038] Comparative Example 4

[0039] The difference between this comparative example and Example 1 is that mechanical stirring is used in step S2. The specific steps are as follows: S1. Take 10g of wood pulp, add 10g of NaOH and 30g of isopropanol, stir until semi-dry, and alkalize at 25℃ for 1 hour. S2. Add 40g of 2,3-epoxypropyltriethylammonium chloride (GTEAC) and 60mL of deionized water to the above product, disperse it with mechanical stirring (350rpm) for 2h, and then place it in a 60℃ constant temperature water bath for 6h. S3. Neutralize to pH 6.5 with 1 mol / L dilute HCl, wash three times with deionized water and anhydrous ethanol, and dry at 80℃ for 12 h to obtain modified cellulose. S4. Take 5g of modified cellulose, add 75g of deionized water, disperse using a high-speed disperser (1200rpm) for 2 hours, and filter to obtain the dispersion.

[0040] Experimental Example

[0041] Performance tests were conducted on each example and comparative example. The Zeta potential was tested according to GB / T 24993-2010 "Determination of Zeta Potential in the Wet End of Papermaking," with the modified cellulose sample prepared into a 0.1% (w / w) aqueous dispersion. The degree of substitution was tested according to the method specified in GB / T 744-2021 "Determination of Degree of Substitution of Cellulose Derivatives," and the data are shown in Table 1. The dispersions with a solid content of 2% obtained from Examples 1-4, Comparative Example 1, and Comparative Example 3 were allowed to stand for 0h, 2h, and 6h / 30 days, and the resulting photographs are shown below. Figure 1 and Figure 2 As shown.

[0042] Table 1

[0043] As shown in Table 1, the cationic cellulose prepared in Examples 1 to 4 has a degree of substitution of 0.65 to 0.85 and a zeta potential of +26.0 to +35.0 mV, all exhibiting strong positive charge. In contrast, Comparative Example 1, without cationic modification, has a zeta potential of -15.2 mV and a degree of substitution of 0, retaining the negative charge characteristics of natural cellulose.

[0044] Example 1: Using a composite cationic modifier (GTEAC+CHPTMAC), isopropanol, and a high-speed shearing process with zirconium beads, the degree of substitution and zeta potential were both the highest, indicating that this process can maximize hydroxyl activation and modifier grafting efficiency. Comparative Example 2: Without the addition of isopropanol, the degree of substitution and zeta potential decreased significantly, proving that isopropanol plays a key role in improving the uniformity of modifier dispersion and promoting the grafting reaction. Comparative Example 3: Using a silane-modified cationic process and low-temperature alkalization, its degree of substitution and zeta potential were lower than those of the examples in this application, and the dispersion showed significant sedimentation after standing for 2-6 hours and exhibited hydrophobicity, further verifying the superiority of the process of this invention in terms of hydrophilicity and stable dispersion.

[0045] As shown in Figures 1 and 2, the dispersions of Examples 1 to 4 remained uniform and without stratification after standing for 30 days, while the dispersions of Comparative Examples 1 and 3 showed stratification or precipitation after standing for 2-6 hours. This indicates that high substitution degree and high positive Zeta potential can effectively inhibit fiber aggregation and significantly improve the long-term stability of the dispersion through electrostatic repulsion and steric hindrance effects.

[0046] This invention significantly improves the degree of substitution and Zeta potential of cationic modification through the synergistic effect of room temperature alkalization, organic solvent system, and high-speed shearing, thereby greatly enhancing the dispersion stability of cellulose in water and overcoming the defects of uneven modification, low degree of substitution, and poor dispersibility in the prior art.

[0047] In summary, the highly substituted cationic cellulose dispersion and its preparation method according to the embodiments of this application have the following advantages: 1. High degree of substitution and high zeta potential: This application achieves full activation of wood pulp fibers and uniform grafting of modifiers through semi-dry room temperature alkalization combined with high-speed shear dispersion. The degree of substitution of modified cellulose can reach 0.6-0.7, and the zeta potential is increased to +26mV to +35mV, which significantly enhances the adsorption capacity for anionic substances.

[0048] 2. Excellent dispersion stability: In the dispersion step, this application uses a high-speed shearing process to refine the modified cellulose particles to the nanoscale. Combined with the electrostatic repulsion of cationic groups, the dispersion can be stably dispersed in water for more than 30 days without obvious precipitation.

[0049] 3. Low energy consumption: This application adopts room temperature alkalization, which does not require additional heating or cooling equipment. It can be directly connected with the subsequent 60℃ modification process, simplifying the temperature control process and reducing energy consumption by 15%-20%.

[0050] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A method for preparing a highly substituted cationic cellulose dispersion, characterized in that, Includes the following steps: S1. Add an alkaline solution to the wood pulp and stir well to alkalize the wood pulp; S2. Add cationic modifier and organic solvent to the alkalized wood pulp, perform high-speed shear dispersion, and then carry out a constant-temperature reaction; S3. After the isothermal reaction is completed, the product is neutralized with acid, and then the modified cellulose is obtained after washing and drying. S4. Take the above modified cellulose, add water, disperse by high-speed shearing, and filter to obtain the highly substituted cationic cellulose dispersion.

2. The method for preparing a highly substituted cationic cellulose dispersion according to claim 1, characterized in that, The alkaline solution in step S1 is prepared by dissolving sodium hydroxide in 3-6 times its mass of deionized water; the mass ratio of wood pulp to sodium hydroxide is 1:(0.5-1).

3. The method for preparing a highly substituted cationic cellulose dispersion according to claim 1, characterized in that, The alkalization temperature in step S1 is 25-30℃, and the alkalization time is 0.5-2h.

4. The method for preparing a highly substituted cationic cellulose dispersion according to claim 1, characterized in that, The organic solvent in step S2 includes one or more of isopropanol, ethanol, tetrahydrofuran, DMAC, and DMSO.

5. The method for preparing a highly substituted cationic cellulose dispersion according to claim 1, characterized in that, In step S2, the cationic modifier is one or more of 3-chloro-2-hydroxypropyltrimethylammonium chloride, glycidyltrimethylammonium chloride, 2,3-epoxypropyltriethylammonium chloride, and 3-chloro-2-hydroxypropyltriethylammonium chloride.

6. The method for preparing a highly substituted cationic cellulose dispersion according to claim 1, characterized in that, In step S2, the ratio of the amount of cationic modifier and organic solvent added to the wood pulp in step S1 is 2-6g: 2-6mL: 1g; the constant temperature reaction temperature is 50-70℃, and the time is 4-8h.

7. The method for preparing a highly substituted cationic cellulose dispersion according to claim 1, characterized in that, The acid solution in step S3 is a 0.5-2 mol / L dilute hydrochloric acid solution, neutralized to 6-7; the cleaning is performed by washing with deionized water and anhydrous ethanol three times each; the drying temperature is 70-100℃ and the drying time is 4-24h.

8. The method for preparing a highly substituted cationic cellulose dispersion according to claim 1, characterized in that, The high-speed shearing in step S2 is performed using one or more combinations of a high-speed disperser, a high-shear emulsifier, a colloid mill, and mechanical stirring. When the equipment is a high-speed disperser, the zircon bead particle size is 0.5-2 mm, and the equipment rotation speed is 500-1000 rpm. When the equipment is a high-shear emulsifier, the rotor speed is 10000-20000 rpm, and the processing time is 1-3 hours. When the equipment is a colloid mill, the grinding disc gap is 5-50 μm, the rotation speed is 3000-8000 rpm, and the processing time is 1-2 hours. When the equipment is mechanical stirring, the stirring speed is 300-500 rpm, and the processing time is 1-3 hours.

9. The method for preparing a highly substituted cationic cellulose dispersion according to claim 1, characterized in that, The high-speed shearing process in step S4 utilizes one or more combinations of a high-speed disperser, a high-shear emulsifier, a sand mill, a bead mill, a colloid mill, and a high-pressure homogenizer. When the equipment is a high-speed disperser, a sand mill, or a bead mill, the zirconium bead particle size is 0.5-2 mm, the equipment linear speed is 8-15 m / s, and the processing time is 1-3 h. When the equipment is a high-shear emulsifier, the rotor speed is 10,000-20,000 rpm, and the processing time is 1-2 h. When the equipment is a high-pressure homogenizer, the working pressure is 50-150 MPa, and the number of homogenization cycles is 3-5. When the equipment is a colloid mill, the grinding disc gap is 5-50 μm, the rotation speed is 3,000-8,000 rpm, and the processing time is 1-2 h.

10. A highly substituted cationic cellulose dispersion, characterized in that, It is prepared by any one of the methods of claims 1-9.

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