A method for preparing a reticulated cellulose ether

Abstract

The application belongs to the technical field of high polymer materials, and discloses a preparation method of reticular cellulose ether, characterized by comprising the following steps: adding an alkalizing agent into cellulose raw materials to obtain alkalized cellulose; sequentially or simultaneously adding an etherifying agent and a tripolyphosphate crosslinking agent into the alkalized cellulose, and performing heat preservation reaction to obtain nascent reticular cellulose ether; and performing neutralization, washing and drying on the nascent reticular cellulose ether to obtain the reticular cellulose ether. The application solves the problems of high-temperature reaction, complex process and biological toxicity existing in the existing preparation method, and realizes the preparation of the reticular cellulose ether with low energy consumption, simple process and green environmental protection.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a method for preparing a network cellulose ether. Background Technology

[0002] In the fields of materials science and chemical engineering, cellulose ethers are widely used in various industries such as construction, food, medicine, and daily chemicals due to their unique physicochemical properties, such as thickening, emulsification, dispersion, and film formation. As the performance requirements of cellulose ethers in various industries continue to increase, research on their preparation methods has become increasingly in-depth. In existing technologies, phosphate crosslinking of cellulose ethers is an important means of improving their performance, typically using sodium trimetaphosphate or sodium hexametaphosphate as crosslinking agents. However, this traditional crosslinking method has many drawbacks. Regarding reaction conditions, crosslinking using the aforementioned crosslinking agents requires a high-temperature environment above 80°C, which undoubtedly increases energy consumption costs significantly. Simultaneously, the entire preparation process requires stepwise alkalization, etherification, and crosslinking, making the steps cumbersome and complex. This not only prolongs the production cycle but also increases the operational difficulty and management costs during production, hindering large-scale industrial production. From an environmental and safety perspective, sodium trimetaphosphate exhibits certain biotoxicity. In today's context of the growing acceptance of green chemistry concepts and increasingly stringent requirements for product safety and environmental friendliness across industries, the use of biotoxic crosslinking agents clearly does not meet the needs of modern development. This not only limits the application of cellulose ethers in some fields with extremely high safety requirements, such as the food and pharmaceutical industries, but may also pose potential hazards to the environment and human health during production, use, and waste disposal.

[0003] In summary, developing a novel method for preparing reticulated cellulose ethers, overcoming the problems of high-temperature reactions, complex processes, and biotoxicity in existing technologies, has become a key issue urgently needing to be addressed in this field. This will not only help promote the sustainable development of cellulose ether-related industries but also meet the urgent needs of various industries for high-performance, environmentally friendly cellulose ether products. Summary of the Invention

[0004] In order to solve the above-mentioned technical problems, this invention proposes a method for preparing reticulated cellulose ethers, which solves the problems of high-temperature reaction, complex process and biotoxicity in existing preparation methods, and realizes the preparation of reticulated cellulose ethers with low energy consumption, simple process and green environmental protection.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a reticulated cellulose ether includes the following steps:

[0007] S1. Add an alkalizing agent to the cellulose raw material to obtain alkalized cellulose;

[0008] S2. Etherifying agent and tripolyphosphate crosslinking agent are added sequentially or simultaneously to alkalized cellulose, and the reaction is kept at a certain temperature to obtain nascent network cellulose ether.

[0009] S3. The nascent network cellulose ether is neutralized, washed and dried to obtain the network cellulose ether.

[0010] Traditional processes require alkalization, etherification, and cross-linking in separate steps, which are cumbersome and complex. This invention allows for the sequential or simultaneous addition of etherifying agents and tripolyphosphate cross-linking agents to alkalized cellulose. This innovative approach greatly simplifies the process, integrating previously disparate multi-step operations, significantly improving production efficiency, and creating highly favorable conditions for large-scale industrial production. This helps companies expand their production scale and increase market share. Furthermore, using tripolyphosphate cross-linking agents instead of biotoxic sodium trimetaphosphate fully complies with the requirements of green chemistry, fundamentally solving the biotoxicity problem caused by cross-linking agents in traditional processes.

[0011] Preferably, in step S1, the alkalizing agent is a sodium hydroxide solution.

[0012] Preferably, in step S2, the etherifying agent is chloroacetic acid or ethylene oxide.

[0013] Preferably, in step S2, the tripolyphosphate crosslinking agent is a sodium tripolyphosphate crosslinking agent.

[0014] Preferably, in step S2, the heat preservation reaction temperature is controlled at 60-70℃.

[0015] The present invention controls the etherification and crosslinking reaction temperatures within a relatively low range. Compared to the traditional process where sodium trimetaphosphate or sodium hexametaphosphate is used for crosslinking and requires a high temperature reaction above 80°C, the present invention greatly reduces the heat energy required for the reaction.

[0016] Preferably, in step S1, trisodium citrate-hollow mesoporous nano silica composite particles are also added to the cellulose raw material.

[0017] Preferably, the preparation method of the trisodium citrate-hollow mesoporous nano-silica composite particles includes the following steps:

[0018] S11. The mesoporous silica powder is calcined, then dispersed in anhydrous ethanol and ultrasonically treated. After centrifugation, it is vacuum dried to obtain pretreated mesoporous silica.

[0019] S12. Dissolve trisodium citrate in deionized water to prepare a trisodium citrate solution;

[0020] S13. Mix the pretreated mesoporous silica with a trisodium citrate solution, evacuate to -0.1 MPa and maintain for 30 minutes, then stir at 60°C for 12 hours, centrifuge and wash with ethanol to obtain loaded trisodium citrate mesoporous silica.

[0021] S14. The trisodium citrate-loaded mesoporous silica was dispersed in an anhydrous ethanol solution of octadecyltrimethoxysilane, and refluxed at 60°C for 6 hours under nitrogen protection. After centrifugation and washing, it was heat-cured in a nitrogen atmosphere to obtain trisodium citrate-hollow mesoporous nano silica composite particles.

[0022] In the technical solution of this invention, as described above, cellulose ether is generated by crosslinking cellulose with sodium tripolyphosphate. However, after in-depth research, the invention team discovered the following problem: cellulose raw materials naturally contain trace amounts of metal ions (such as Ca²⁺, Mg²⁺, Fe³⁺, etc.). Sodium tripolyphosphate crosslinking agent is prone to hydrolysis under the catalysis of these metal ions, causing it to lose its crosslinking activity and resulting in a decrease in the crosslinking density of the generated cellulose ether. To further solve the above technical problems, this invention adds trisodium citrate-hollow mesoporous nano-silica composite particles to the cellulose raw material.

[0023] The unique porous structure of hollow mesoporous nano-silica exhibits a strong adsorption effect on metal ions, enriching them in its surroundings. Simultaneously, the chelating effect of trisodium citrate on metal ions is fully utilized, effectively preventing the catalytic hydrolysis of sodium tripolyphosphate by metal ions. This allows for efficient cross-linking reactions, significantly improving the degree of cross-linking in cellulose and laying a solid foundation for the preparation of high-performance network cellulose ethers. Secondly, from the perspective of sustained release and continuous action, the composite particle preparation process is ingenious. Trisodium citrate is first loaded into the porous structure of hollow mesoporous nano-silica, and then octadecyltrimethoxysilane is grafted onto its surface. Under heating conditions, octadecyltrimethoxysilane undergoes cross-linking, forming a stable cross-linked structure. This structure provides excellent sustained release for trisodium citrate. When the composite particles are added to the cellulose raw material, they continuously release trisodium citrate, allowing it to fully chelate with metal ions, continuously optimizing the cross-linking reaction environment, further enhancing the cross-linking effect of cellulose, and ensuring the stability of the preparation process and the uniformity of product quality.

[0024] Preferably, in step S11, the mesoporous silica has a pore size of 5-10 nm and a specific surface area greater than 800 m² / g.

[0025] Preferably, in step S12, the concentration of the trisodium citrate solution is 0.6-1.4 mol / L.

[0026] Preferably, in step S14, the mass ratio of the loaded trisodium citrate mesoporous silica to octadecyltrimethoxysilane is 1:0.6-0.8.

[0027] If the amount of octadecyltrimethoxysilane is too small, it will be difficult to form a sufficiently dense cross-linked structure. This will directly weaken the sustained-release effect of trisodium citrate, preventing trisodium citrate from continuously and stably chelating metal ions in the cellulose raw material. Consequently, the tripolyphosphate cross-linking agent will hydrolyze under the catalysis of metal ions, ultimately resulting in a significant decrease in the degree of cross-linking of the cellulose ether. Therefore, in this invention, the lower limit of the mass ratio of loaded trisodium citrate mesoporous silica to octadecyltrimethoxysilane is strictly controlled at 1:0.6 to ensure the effective construction of the cross-linked structure and the sustained-release effect. However, the invention team unexpectedly discovered that when the mass ratio of loaded trisodium citrate mesoporous silica to octadecyltrimethoxysilane was controlled to be less than 1:0.8, the yield of cellulose ether prepared by further increasing the amount of octadecyltrimethoxysilane decreased significantly. This may be because there are gaps between the cellulose molecular chains and some nonpolar regions on its surface. Octadecyltrimethoxysilane molecules have a long-chain alkyl structure and strong hydrophobicity and nonpolarity. In the preparation system, octadecyltrimethoxysilane interacts with these sites of cellulose molecules through van der Waals forces, resulting in physical adsorption. This physical adsorption causes cellulose and octadecyltrimethoxysilane to bind together, greatly increasing the difficulty of separation during subsequent processing. During the separation process, a large amount of cellulose is lost, ultimately leading to a decrease in the yield of cellulose ether. Therefore, this invention strictly controls the mass ratio of loaded trisodium citrate mesoporous silica to octadecyltrimethoxysilane to be greater than 1:0.8.

[0028] The present invention has the following beneficial effects:

[0029] (1) Simplified process flow: Traditional process involves alkalization, etherification and crosslinking in separate steps, which is cumbersome. This invention allows the addition of etherifying agent and tripolyphosphate crosslinking agent to alkalized cellulose sequentially or simultaneously, integrating multiple operations, greatly improving production efficiency, facilitating large-scale industrial production, and helping enterprises expand their scale and increase their market share.

[0030] (2) Green and environmentally friendly: Sodium tripolyphosphate crosslinking agent is used to replace sodium trimetaphosphate which is biotoxic, which meets the requirements of green chemistry and solves the problem of biotoxicity of crosslinking agent in traditional process from the source;

[0031] (3) Reduced energy consumption: The etherification and cross-linking reaction temperature is controlled at 60-70℃, which is significantly lower than the high temperature reaction of 80℃ or above when using sodium trimetaphosphate or sodium hexametaphosphate for cross-linking in traditional processes.

[0032] (4) Improve cross-linking degree: Add trisodium citrate-hollow mesoporous nano silica composite particles to cellulose raw materials. The pore structure of hollow mesoporous nano silica adsorbs metal ions, and trisodium citrate chelates metal ions, avoiding the hydrolysis of sodium tripolyphosphate, and carrying out cross-linking reaction efficiently, which significantly improves the cross-linking degree of cellulose. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In specific embodiments, the pore size of mesoporous silica is 5-10 nm, and the specific surface area is greater than 800 m² / g.

[0034] Example 1: A method for preparing a reticulated cellulose ether, comprising the following steps:

[0035] S1. Add 100g of cotton linter cellulose raw material and 3g of trisodium citrate-hollow mesoporous nano silica composite particles to 500mL of sodium hydroxide solution (18wt%), heat to 25℃, stir and alkalize for 3h, and then remove the solid nanoparticles by centrifugation to obtain alkalized cellulose.

[0036] S2. Transfer the alkalized cellulose to the reaction vessel, add 15g of chloroacetic acid etherifying agent and 8g of sodium tripolyphosphate crosslinking agent, and keep the reaction at 65℃ for 4h to obtain the nascent network cellulose ether.

[0037] S3. Add 10% hydrochloric acid to the nascent reticulated cellulose ether to adjust the pH to 7, and then wash and dry to obtain the reticulated cellulose ether.

[0038] Preparation of trisodium citrate-hollow mesoporous silica nanocomposite particles:

[0039] S11. Spread 60g of mesoporous silica powder evenly in a corundum crucible, place it in a muffle furnace, heat it to 550℃ at 2℃ / min, calcine for 4h, cool it to room temperature, weigh 5g of calcined powder, disperse it in 200mL of anhydrous ethanol, sonicate it for 1h (power 500 W, frequency 40 kHz), then centrifuge it, and dry the solid product in a vacuum drying oven at 60°C for 8h to obtain pretreated mesoporous silica.

[0040] S12. Dissolve trisodium citrate in deionized water and stir magnetically until completely dissolved to prepare a trisodium citrate solution with a concentration of 1.2 mol / L.

[0041] S13. Mix 6g of pretreated mesoporous silica with 80mL of trisodium citrate solution, evacuate to -0.1 MPa and maintain for 30 minutes to allow the solution to fully penetrate the pores, then stir at 60°C for 12 hours, centrifuge and wash 3 times with ethanol, and then vacuum dry at 60°C for 3 hours to obtain loaded trisodium citrate mesoporous silica.

[0042] S14. The trisodium citrate-loaded mesoporous silica was dispersed in 200 mL of anhydrous ethanol solution containing 6 g of octadecyltrimethoxysilane. The mass ratio of the trisodium citrate-loaded mesoporous silica to octadecyltrimethoxysilane was 1:0.7. The reaction was carried out under nitrogen protection and refluxed at 60°C for 6 hours. After centrifugation and washing, the mixture was heat-cured at 80°C under nitrogen atmosphere for 3 hours to obtain trisodium citrate-hollow mesoporous nano silica composite particles.

[0043] Example 2: A method for preparing a reticulated cellulose ether, comprising the following steps:

[0044] S1. Add 100g of cotton linter cellulose raw material and 3g of trisodium citrate-hollow mesoporous nano silica composite particles to 500mL of sodium hydroxide solution (18wt%), heat to 25℃, stir and alkalize for 3h, and then remove the solid nanoparticles by centrifugation to obtain alkalized cellulose.

[0045] S2. Transfer the alkalized cellulose to the reaction vessel, add 15g of ethylene oxide etherifying agent and 8g of sodium tripolyphosphate crosslinking agent, and keep the reaction at 65℃ for 4h to obtain the nascent network cellulose ether.

[0046] S3. Add 10% hydrochloric acid to the nascent reticulated cellulose ether to adjust the pH to 7, and then wash and dry to obtain the reticulated cellulose ether.

[0047] Preparation of trisodium citrate-hollow mesoporous silica nanocomposite particles:

[0048] S11. Spread 60g of mesoporous silica powder evenly in a corundum crucible, place it in a muffle furnace, heat it to 550℃ at 2℃ / min, calcine for 4h, cool it to room temperature, weigh 5g of calcined powder, disperse it in 200mL of anhydrous ethanol, sonicate it for 1h (power 500 W, frequency 40 kHz), then centrifuge it, and dry the solid product in a vacuum drying oven at 60°C for 8h to obtain pretreated mesoporous silica.

[0049] S12. Dissolve trisodium citrate in deionized water and stir magnetically until completely dissolved to prepare a trisodium citrate solution with a concentration of 0.8 mol / L.

[0050] S13. Mix 6g of pretreated mesoporous silica with 80mL of trisodium citrate solution, evacuate to -0.1 MPa and maintain for 30 minutes to allow the solution to fully penetrate the pores, then stir at 60°C for 12 hours, centrifuge and wash 3 times with ethanol, and then vacuum dry at 60°C for 3 hours to obtain loaded trisodium citrate mesoporous silica.

[0051] S14. The trisodium citrate-loaded mesoporous silica was dispersed in 200 mL of anhydrous ethanol solution containing 6 g of octadecyltrimethoxysilane. The mass ratio of the trisodium citrate-loaded mesoporous silica to octadecyltrimethoxysilane was 1:0.7. The reaction was carried out under nitrogen protection and refluxed at 60°C for 6 hours. After centrifugation and washing, the mixture was heat-cured at 80°C under nitrogen atmosphere for 3 hours to obtain trisodium citrate-hollow mesoporous nano silica composite particles.

[0052] Example 3: A method for preparing a reticulated cellulose ether, comprising the following steps:

[0053] S1. Add 100g of cotton linter cellulose raw material and 3g of trisodium citrate-hollow mesoporous nano silica composite particles to 500mL of sodium hydroxide solution (18wt%), heat to 25℃, stir and alkalize for 3h, and then remove the solid nanoparticles by centrifugation to obtain alkalized cellulose.

[0054] S2. Transfer the alkalized cellulose to the reaction vessel, add 15g of chloroacetic acid etherifying agent and 8g of sodium tripolyphosphate crosslinking agent, and keep the reaction at 65℃ for 4h to obtain the nascent network cellulose ether.

[0055] S3. Add 10% hydrochloric acid to the nascent reticulated cellulose ether to adjust the pH to 7, and then wash and dry to obtain the reticulated cellulose ether.

[0056] Preparation of trisodium citrate-hollow mesoporous silica nanocomposite particles:

[0057] S11. Spread 60g of mesoporous silica powder evenly in a corundum crucible, place it in a muffle furnace, heat it to 550℃ at 2℃ / min, calcine for 4h, cool it to room temperature, weigh 5g of calcined powder, disperse it in 200mL of anhydrous ethanol, sonicate it for 1h (power 500 W, frequency 40 kHz), then centrifuge it, and dry the solid product in a vacuum drying oven at 60°C for 8h to obtain pretreated mesoporous silica.

[0058] S12. Dissolve trisodium citrate in deionized water and stir magnetically until completely dissolved to prepare a 1.0 mol / L trisodium citrate solution.

[0059] S13. Mix 6g of pretreated mesoporous silica with 80mL of trisodium citrate solution, evacuate to -0.1 MPa and maintain for 30 minutes to allow the solution to fully penetrate the pores, then stir at 60°C for 12 hours, centrifuge and wash 3 times with ethanol, and then vacuum dry at 60°C for 3 hours to obtain loaded trisodium citrate mesoporous silica.

[0060] S14. The trisodium citrate-loaded mesoporous silica was dispersed in 200 mL of anhydrous ethanol solution containing 6 g of octadecyltrimethoxysilane. The mass ratio of the trisodium citrate-loaded mesoporous silica to octadecyltrimethoxysilane was 1:0.7. The reaction was carried out under nitrogen protection and refluxed at 60°C for 6 hours. After centrifugation and washing, the mixture was heat-cured at 80°C under nitrogen atmosphere for 3 hours to obtain trisodium citrate-hollow mesoporous nano silica composite particles.

[0061] Example 4: A method for preparing a reticulated cellulose ether, comprising the following steps:

[0062] S1. Add 100g of cotton linter cellulose raw material and 3g of trisodium citrate-hollow mesoporous nano silica composite particles to 500mL of sodium hydroxide solution (18wt%), heat to 25℃, stir and alkalize for 3h, and then remove the solid nanoparticles by centrifugation to obtain alkalized cellulose.

[0063] S2. Transfer the alkalized cellulose to the reaction vessel, add 15g of ethylene oxide etherifying agent and 8g of sodium tripolyphosphate crosslinking agent, and keep the reaction at 70℃ for 4h to obtain the nascent network cellulose ether.

[0064] S3. Add 10% hydrochloric acid to the nascent reticulated cellulose ether to adjust the pH to 7, and then wash and dry to obtain the reticulated cellulose ether.

[0065] Preparation of trisodium citrate-hollow mesoporous silica nanocomposite particles:

[0066] S11. Spread 60g of mesoporous silica powder evenly in a corundum crucible, place it in a muffle furnace, heat it to 550℃ at 2℃ / min, calcine for 4h, cool it to room temperature, weigh 5g of calcined powder, disperse it in 200mL of anhydrous ethanol, sonicate it for 1h (power 500 W, frequency 40 kHz), then centrifuge it, and dry the solid product in a vacuum drying oven at 60°C for 8h to obtain pretreated mesoporous silica.

[0067] S12. Dissolve trisodium citrate in deionized water and stir magnetically until completely dissolved to prepare a trisodium citrate solution with a concentration of 1.4 mol / L.

[0068] S13. Mix 6g of pretreated mesoporous silica with 80mL of trisodium citrate solution, evacuate to -0.1 MPa and maintain for 30 minutes to allow the solution to fully penetrate the pores, then stir at 60°C for 12 hours, centrifuge and wash 3 times with ethanol, and then vacuum dry at 60°C for 3 hours to obtain loaded trisodium citrate mesoporous silica.

[0069] S14. The mesoporous silica loaded with trisodium citrate was dispersed in 200 mL of anhydrous ethanol solution containing 6 g of octadecyltrimethoxysilane. The mass ratio of the mesoporous silica loaded with trisodium citrate to octadecyltrimethoxysilane was 1:0.8. The reaction was carried out under nitrogen protection and refluxed at 60°C for 6 hours. After centrifugation and washing, the mixture was heat-cured at 80°C in a nitrogen atmosphere for 3 hours to obtain trisodium citrate-hollow mesoporous nano silica composite particles.

[0070] Example 5: A method for preparing a reticulated cellulose ether, comprising the following steps:

[0071] S1. Add 100g of cotton linter cellulose raw material and 3g of trisodium citrate-hollow mesoporous nano silica composite particles to 500mL of sodium hydroxide solution (18wt%), heat to 25℃, stir and alkalize for 3h, and then remove the solid nanoparticles by centrifugation to obtain alkalized cellulose.

[0072] S2. Transfer the alkalized cellulose to a reaction vessel, add 15g of chloroacetic acid etherifying agent and 8g of sodium tripolyphosphate crosslinking agent, and keep the reaction at 60℃ for 4h to obtain nascent network cellulose ether.

[0073] S3. Add 10% hydrochloric acid to the nascent reticulated cellulose ether to adjust the pH to 7, and then wash and dry to obtain the reticulated cellulose ether.

[0074] Preparation of trisodium citrate-hollow mesoporous silica nanocomposite particles:

[0075] S11. Spread 60g of mesoporous silica powder evenly in a corundum crucible, place it in a muffle furnace, heat it to 550℃ at 2℃ / min, calcine for 4h, cool it to room temperature, weigh 5g of calcined powder, disperse it in 200mL of anhydrous ethanol, sonicate it for 1h (power 500 W, frequency 40 kHz), then centrifuge it, and dry the solid product in a vacuum drying oven at 60°C for 8h to obtain pretreated mesoporous silica.

[0076] S12. Dissolve trisodium citrate in deionized water and stir magnetically until completely dissolved to prepare a trisodium citrate solution with a concentration of 0.6 mol / L.

[0077] S13. Mix 6g of pretreated mesoporous silica with 80mL of trisodium citrate solution, evacuate to -0.1 MPa and maintain for 30 minutes to allow the solution to fully penetrate the pores, then stir at 60°C for 12 hours, centrifuge and wash 3 times with ethanol, and then vacuum dry at 60°C for 3 hours to obtain loaded trisodium citrate mesoporous silica.

[0078] S14. The trisodium citrate-loaded mesoporous silica was dispersed in 200 mL of anhydrous ethanol solution containing 6 g of octadecyltrimethoxysilane. The mass ratio of the trisodium citrate-loaded mesoporous silica to octadecyltrimethoxysilane was 1:0.6. The reaction was carried out under nitrogen protection and refluxed at 60°C for 6 hours. After centrifugation and washing, the mixture was heat-cured at 80°C under nitrogen atmosphere for 3 hours to obtain trisodium citrate-hollow mesoporous nano silica composite particles.

[0079] Comparative Example 1

[0080] The difference between Comparative Example 1 and Example 1 is as follows:

[0081] In the preparation of reticulated cellulose ethers,

[0082] No trisodium citrate-hollow mesoporous nano silica composite particles are added to the cellulose raw material.

[0083] The remaining operating steps are the same as in Example 1.

[0084] Comparative Example 2

[0085] The difference between Comparative Example 2 and Example 1 is as follows:

[0086] In the preparation of reticulated cellulose ethers,

[0087] Replace the trisodium citrate-hollow mesoporous silica nanocomposite particles with an equal mass of citric acid.

[0088] Trisodium;

[0089] The remaining operating steps are the same as in Example 1.

[0090] Comparative Example 3

[0091] The difference between Comparative Example 3 and Example 5 is as follows:

[0092] The mass ratio of trisodium citrate-loaded mesoporous silica to octadecyltrimethoxysilane is 1:0.5;

[0093] The remaining operating steps are the same as in Example 5.

[0094] Comparative Example 4

[0095] The difference between Comparative Example 4 and Example 4 is as follows:

[0096] The mass ratio of trisodium citrate-loaded mesoporous silica to octadecyltrimethoxysilane is 1:0.9;

[0097] The remaining operating steps are the same as in Example 4.

[0098] Comparative Example 5

[0099] The difference between Comparative Example 5 and Example 4 is as follows:

[0100] The mass ratio of trisodium citrate-loaded mesoporous silica to octadecyltrimethoxysilane is 1:1;

[0101] The remaining operating steps are the same as in Example 4.

[0102] Performance testing

[0103] Cellulose ether crosslinking density test: The crosslinking density of cellulose ether was tested using the swelling method. First, a dry cellulose ether sample with a mass of m1 (accurate to 0.0001 g) was accurately weighed and placed in a stoppered conical flask containing 200 mL of deionized water. The conical flask was placed in a constant-temperature shaker at 25°C and shaken at 100 rpm to allow the sample to fully swell. The soaking time was set to 24 hours. After 24 hours, the swollen sample was removed from the conical flask, gently pressed with filter paper, and the residual deionized water on the surface was carefully absorbed. Then, its mass m2 (accurate to 0.0001 g) was quickly and accurately weighed. Based on the mass change of the sample before and after swelling, i.e., the degree of swelling = (m2-m1) / m1, and combined with the initial volume of the sample, the crosslinking density is calculated using the formula based on the Flory-Rehner theory: 1 / v = -[ln(1 - v2)+v2+χv2²] / V1(v2⅓-v2 / 2) (where v is the crosslinking density, v2 is the polymer volume fraction after swelling, χ is the polymer-solvent interaction parameter, χ is 0.5; V1 is the solvent molar volume, and the molar volume of water is approximately 18.068 cm³ / mol).

[0104] Cellulose ether viscosity test: The viscosity of cellulose ether was tested using a rotational viscometer. First, an appropriate amount of cellulose ether sample was uniformly dispersed in deionized water at a mass ratio of 1:100 to prepare a solution. The solution was stirred evenly and allowed to stand for 24 hours at a constant temperature of 25°C to allow for complete dissolution. A Brookfield DV-Ⅱ+Pro rotational viscometer was used, with the rotation speed set to 60 r / min. The rotor was immersed in the prepared cellulose ether solution to the rotor immersion line. After the instrument reading stabilized, the viscosity value was recorded, and the average value was obtained from multiple measurements.

[0105]

[0106] Cellulose ether yield test:

[0107] The mass of the network cellulose ethers obtained after drying in Examples 1-5 and Comparative Examples 4-5 was accurately weighed using an electronic balance and denoted as m grams. Based on the amount of cotton linter cellulose raw material and the stoichiometric relationship of the reaction, the theoretical yield of cellulose ether was calculated. Assuming that the cotton linter cellulose was completely converted into cellulose ether, the theoretically expected mass of cellulose ether was calculated based on the chemical composition and reaction relationship between cellulose and cellulose ether, and denoted as M grams. The yield of cellulose ether was calculated using the following formula:

[0108] Yield = (m / M) × 100%.

[0109]

[0110] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a reticulated cellulose ether, characterized in that, Includes the following steps: S1. Add an alkalizing agent and trisodium citrate-hollow mesoporous nano silica composite particles to cellulose raw material to obtain alkalized cellulose. The preparation method of the trisodium citrate-hollow mesoporous nano-silica composite particles includes the following steps: S11. The mesoporous silica powder is calcined, then dispersed in anhydrous ethanol and ultrasonically treated. After centrifugation, it is vacuum dried to obtain pretreated mesoporous silica. S12. Dissolve trisodium citrate in deionized water to prepare a trisodium citrate solution; S13. Mix the pretreated mesoporous silica with a trisodium citrate solution, evacuate to -0.1 MPa and maintain for 30 minutes, then stir at 60°C for 12 hours, centrifuge and wash with ethanol to obtain loaded trisodium citrate mesoporous silica. S14. Mesoporous silica loaded with trisodium citrate was dispersed in an anhydrous ethanol solution of octadecyltrimethoxysilane. The mass ratio of the mesoporous silica loaded with trisodium citrate to octadecyltrimethoxysilane was 1:0.6-0.

8. The reaction was carried out under nitrogen protection at 60°C for 6 hours. After centrifugation and washing, the mixture was heat-cured in a nitrogen atmosphere to obtain trisodium citrate-hollow mesoporous nano silica composite particles. S2. Etherifying agent and tripolyphosphate crosslinking agent are added sequentially or simultaneously to alkalized cellulose, and the reaction is kept at a certain temperature to obtain nascent network cellulose ether. S3. The nascent network cellulose ether is neutralized, washed and dried to obtain the network cellulose ether.

2. The method for preparing a reticulated cellulose ether according to claim 1, characterized in that, In step S1, the alkalizing agent is a sodium hydroxide solution.

3. The method for preparing a reticulated cellulose ether according to claim 1, characterized in that, In step S2, the etherifying agent is chloroacetic acid or ethylene oxide.

4. The method for preparing a reticulated cellulose ether according to claim 1, characterized in that, In step S2, the tripolyphosphate crosslinking agent is sodium tripolyphosphate crosslinking agent.

5. The method for preparing a reticulated cellulose ether according to claim 1, characterized in that, In step S2, the heat preservation reaction temperature is controlled at 60-70℃.

6. The method for preparing a reticulated cellulose ether according to claim 1, characterized in that, In step S11, the mesoporous silica has a pore size of 5-10 nm and a specific surface area greater than 800 m² / g.

7. The method for preparing a reticulated cellulose ether according to claim 1, characterized in that, In step S12, the concentration of the trisodium citrate solution is 0.6-1.4 mol / L.

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