Carboxymethyl modified bamboo fiber diversion paper as well as preparation method and application thereof

Abstract

The invention relates to the field of diversion paper, in particular to carboxymethyl modified bamboo fiber diversion paper and a preparation method and application thereof.The preparation method comprises the steps that S1, bamboo fibers are soaked in sodium hydroxide to obtain an activation system containing activated bamboo fibers; s2, sodium chloroacetate is added into the activation system containing the activated bamboo fibers, and carboxymethylated bamboo fibers are obtained; s3, excessive acid is added into the carboxymethylated bamboo fibers, washing is performed after sufficient reaction, and carboxymethyl modified bamboo fibers are obtained; s4, after the carboxymethyl modified bamboo fibers and the unmodified bamboo fibers are mixed and dispersed, a cationic polyester wet strength agent is added for papermaking forming, and the carboxymethyl modified bamboo fiber diversion paper is obtained after drying. According to the carboxymethyl modified bamboo fiber diversion paper, carboxymethyl is introduced to the bamboo fibers, the hydrophilicity of the bamboo fibers can be effectively improved, the diversion efficiency of the carboxymethyl modified bamboo fiber diversion paper is improved, then the carboxymethyl modified bamboo fibers and the unmodified bamboo fibers are mixed to prepare the carboxymethyl modified bamboo fiber diversion paper, and the carboxymethyl modified bamboo fiber diversion paper further has ideal tensile strength.

Description

Technical Field

[0001] This application relates to the field of flow-guiding paper, and in particular to a carboxymethyl modified bamboo fiber flow-guiding paper, its preparation method, and its application. Background Technology

[0002] Because bamboo fibers are significantly longer than ordinary wood pulp fibers, they can form a denser and more uniform network structure, which improves the mechanical strength and flexibility of the paper. The cell walls of bamboo fibers also have abundant micropores, and the naturally formed pore structure is conducive to the transport of liquids. In addition, bamboo has strong regenerative properties, so it is often used to prepare bamboo fiber paper.

[0003] However, bamboo fibers often exhibit a dense, entangled state, leading to a decrease in porosity and consequently reducing the flow-guiding efficiency of bamboo fiber conductive paper, failing to meet the demands of modern industry for efficient liquid transport. Currently, to improve the entangled and dense state of bamboo fibers, researchers often use solvent methods to modify them through carboxymethylation. However, the use of solvent methods has significant drawbacks. On the one hand, the use of large amounts of organic solvents easily causes environmental pollution; on the other hand, solvent methods can damage the original orientation of bamboo fibers during modification, significantly reducing their performance. Therefore, there is an urgent need to develop a green and environmentally friendly process that can effectively regulate interfacial forces to optimize the pore structure. Summary of the Invention

[0004] In order to obtain a flow-guiding paper with excellent flow-guiding efficiency, this application provides a carboxymethyl modified bamboo fiber flow-guiding paper, its preparation method and application.

[0005] Firstly, this application provides a method for preparing carboxymethyl modified bamboo fiber diffusing paper, which adopts the following technical solution: A method for preparing carboxymethyl modified bamboo fiber diversion paper includes the following steps: S1. Bamboo fibers are activated by immersing them in sodium hydroxide to obtain an activated system containing activated bamboo fibers; S2. Sodium chloroacetate is added to the activation system containing activated bamboo fiber to carry out the reaction at a temperature of 50-70℃ for 2-4 hours to obtain carboxymethylated bamboo fiber. S3. Add excess acid to carboxymethylated bamboo fiber, and after the reaction is complete, wash until neutral and detect no chloride ion residue to obtain carboxymethyl modified bamboo fiber. S4. After mixing and dispersing carboxymethyl modified bamboo fiber with unmodified bamboo fiber, the mixture is formed into a preliminary bamboo fiber guide paper. Then, a cationic polyester wet strength agent is sprayed onto the surface of the preliminary bamboo fiber guide paper, and after drying, the carboxymethyl modified bamboo fiber guide paper is obtained.

[0006] By adopting the above technical solution, bamboo fiber is first activated with sodium hydroxide to destroy the hydrogen bond network and crystal structure of cellulose molecular chains, exposing its internal hydroxyl groups. Then, the activated bamboo fiber is reacted with sodium chloroacetate under alkaline conditions to carboxymethylate the bamboo fiber. Carboxymethyl groups are hydrophilic anionic groups. The introduction of carboxymethyl groups can increase the spacing between bamboo fiber molecular chains, significantly reduce the physical entanglement between bamboo fibers, and in aqueous solution, these negatively charged groups will repel each other, absorbing a large number of water molecules into the interior of the bamboo fiber, causing the bamboo fiber to swell, thereby opening up the micropores and channels inside the bamboo fiber and increasing the porosity of the bamboo fiber.

[0007] Then, adding excess acid to the reaction system converts the water-soluble sodium carboxylate into free carboxylic acid. This is because sodium carboxymethyl cellulose is a water-soluble polymer that rapidly swells in water to form a viscous gel solution, making it impossible for it to exist as an independent fiber. Carboxymethyl cellulose, on the other hand, can exist as fibers, allowing for the construction of a "dual-network" structure in paper that provides both mechanical strength and efficient flow. Simultaneously, the excess acid washes away excess sodium hydroxide and salts, resulting in pure modified fibers.

[0008] Finally, a cationic polyester wet-strength agent is sprayed onto the surface of the pre-formed bamboo fiber conductive paper. The addition of the cationic polyester wet-strength agent helps form a water-resistant covalent cross-linked network between the fibers. Furthermore, its addition after paper forming helps reduce the probability of charge conflict between the cationic polyester wet-strength agent and the carboxymethyl modified bamboo fiber, ensuring uniform dispersion of the bamboo fiber and the efficiency of the cationic polyester wet-strength agent. Compared to the traditional solvent-based preparation of carboxymethyl modified bamboo fiber, the preparation method of this application is more environmentally friendly, and the resulting carboxymethyl modified bamboo fiber conductive paper maintains good conductivity while ensuring necessary tensile strength.

[0009] This application introduces carboxymethyl groups onto bamboo fibers. The presence of carboxymethyl groups can effectively improve the hydrophilicity and porosity of bamboo fibers, allowing liquids to spread and penetrate rapidly on their surface, thus effectively improving the flow efficiency of carboxymethyl modified bamboo fiber flow-guiding paper. Furthermore, by mixing carboxymethyl modified bamboo fibers with unmodified bamboo fibers, the carboxymethyl modified bamboo fiber flow-guiding paper not only possesses excellent flow efficiency but also ideal tensile strength.

[0010] Preferably, in S2, the mass ratio of sodium chloroacetate to the cellulose hydroxyl groups in the activated bamboo fiber is 0.8-1:2-2.2.

[0011] By adopting the above technical solution, when the mass ratio of sodium chloroacetate to the cellulose hydroxyl groups in the activated bamboo fiber is 0.8-1:2-2.2, the degree of substitution of the obtained carboxymethyl modified bamboo fiber is 0.2-0.5, and the Zeta potential is -20mV to -50mV. When the mass ratio of sodium chloroacetate is too high, the excess sodium chloroacetate will cause the bamboo fiber to have an extremely high degree of substitution, making the bamboo fiber prone to excessive water absorption and swelling, and unable to shrink back after drying. This results in a decrease in the wet tensile strength of the carboxymethyl modified bamboo fiber conductive paper, and at the same time, a decrease in pore uniformity, leading to a decrease in the conductivity of the carboxymethyl modified bamboo fiber conductive paper. When the mass ratio of sodium chloroacetate is too low, the amount of sodium chloroacetate added is insufficient, and the hydroxyl groups of cellulose cannot be fully channeled, resulting in a decrease in the hydrophilicity of the carboxymethyl modified bamboo fiber conductive paper.

[0012] Preferably, the concentration of the cationic polyester wet strength agent is 0.2-2 wt%.

[0013] By adopting the above technical solution, when the concentration of cationic polyester wet strength agent is 0.2-2wt%, it can enhance the interaction between its cationic groups and the carboxyl and hydroxyl groups on the fiber surface to improve the crosslinking efficiency. While ensuring the formation of an effective water-resistant crosslinking network to improve wet tensile strength, it avoids damage to the pore structure due to excessively high local concentration, thus ensuring that the conductive paper has both good wet strength and conductivity.

[0014] When the concentration of cationic polyester wet strength agent is too low, the cationic polyester wet strength agent molecules cannot form enough cross-linking networks between fibers, resulting in a decrease in the tensile strength of carboxymethyl modified bamboo fiber conductive paper. When the concentration of cationic polyester wet strength agent is too high, after the negative charge on the fiber surface is completely neutralized, the excess cationic polyester wet strength agent will cause the surface charge to reverse from negative to positive, resulting in strong electrostatic attraction between fibers, which reduces the tensile strength of carboxymethyl modified bamboo fiber conductive paper. Furthermore, excessive cationic polyester wet strength agent will cause excessive cross-linking between fibers, which increases the hardness of carboxymethyl modified bamboo fiber conductive paper.

[0015] Preferably, the cationic polyester wet strength agent is 1-2% of the mass of carboxymethyl modified bamboo fiber.

[0016] By adopting the above technical solution, when the proportion of cationic polyester wet strength agent is too high, because the cationic polyester wet strength agent contains a large number of non-polar structures, its polarization degree is not ideal, and the overall structure is hydrophobic. Therefore, the excessive cationic polyester wet strength agent will cover the surface of carboxymethyl modified bamboo fiber with a hydrophobic film. The presence of this film will shield the hydrophilic groups of carboxymethyl modified bamboo fiber, making it change from a hydrophilic surface to a hydrophobic surface, which will seriously weaken the conductivity and lead to a decrease in the dry tensile strength of carboxymethyl modified bamboo fiber conductive paper. When the proportion of cationic polyester wet strength agent is too low, the cationic polyester wet strength agent is insufficient to cover the highly negatively charged surface of carboxymethyl modified fiber, making it difficult to form an effective water-resistant cross-linking network, resulting in insufficient wet tensile strength. When exposed to liquid, the fiber bond is loose, the paper structure is easy to collapse, and the functionality is lost.

[0017] Preferably, in step S4, sulfonated lignin is also added. After mixing and dispersing the sulfonated lignin, carboxymethyl modified bamboo fiber and unmodified bamboo fiber, the mixture is formed into a preliminary bamboo fiber guide paper. Then, a cationic polyester wet strength agent is sprayed onto the surface of the preliminary bamboo fiber guide paper, and after drying, a carboxymethyl modified bamboo fiber guide paper is obtained.

[0018] By adopting the above technical solution, sulfonated lignin contains hydrophilic sulfonic acid groups, which can synergistically enhance the hydrophilicity of the system with carboxymethyl groups and improve the conductivity of carboxymethyl modified bamboo fiber.

[0019] Sulfonated lignin is an anionic surfactant that can be adsorbed onto the surface of fibers to increase negative charge, enhance electrostatic repulsion between fibers, improve the mixing uniformity of carboxymethyl modified bamboo fibers and unmodified bamboo fibers, and form a more uniform fiber network.

[0020] Sulfonated lignin can also combine with cationic polyester wet strength agents through ionic bonds to form a three-dimensional cross-linking bridge of "fiber-lignin-wet strength agent", which improves the adsorption efficiency of cationic polyester wet strength agents on the fiber surface and improves the wet tensile strength of carboxymethyl modified bamboo fiber.

[0021] Preferably, the amount of sulfonated lignin added is 1-5% of the total mass of oven-dried modified bamboo fiber and oven-dried unmodified bamboo fiber.

[0022] By adopting the above technical solution, when the amount of sulfonated lignin added is too low, the fiber dispersion is insufficient, and the unmodified bamboo fiber and carboxymethyl modified fiber are prone to flocculation, resulting in poor paper uniformity and fluctuating flow properties. In addition, the cationic polyester wet strength agent is difficult to crosslink effectively due to insufficient charge shielding, and the improvement of wet tensile strength is limited. When the amount of sulfonated lignin added is too high, the excessive anionic sulfonic acid groups will seriously hinder the adsorption and crosslinking of the subsequent cationic polyester wet strength agent, significantly weakening the wet strength. At the same time, lignin aggregates and blocks the fiber pores and covers the hydrophilic groups, reducing the flow efficiency.

[0023] Preferably, the unmodified bamboo fiber accounts for 20-80% of the total mass of carboxymethyl modified bamboo fiber and unmodified bamboo fiber.

[0024] By adopting the above technical solution, unmodified bamboo fiber can serve as a high-strength skeleton support, preventing pure carboxymethyl modified bamboo fiber from becoming brittle due to insufficient strength when it is made into paper. The carboxyl groups of carboxymethyl modified bamboo fiber provide hydrophilicity, drive capillary effect to accelerate liquid transport, and ensure the flow efficiency of carboxymethyl modified bamboo fiber guide paper. By adjusting the ratio between unmodified bamboo fiber and carboxymethyl modified bamboo fiber, the prepared carboxymethyl modified bamboo fiber guide paper can adapt to different application requirements.

[0025] Secondly, the carboxymethyl modified bamboo fiber diversion paper provided in this application adopts the following technical solution: A carboxymethyl modified bamboo fiber drainage paper is prepared by the preparation method of carboxymethyl modified bamboo fiber drainage paper according to any one of claims 1-8.

[0026] Thirdly, the application of the carboxymethyl modified bamboo fiber diversion paper provided in this application adopts the following technical solution: An application of a carboxymethyl modified bamboo fiber guide paper, specifically the application of the carboxymethyl modified bamboo fiber guide paper as described in claim 9 in water filtration.

[0027] In summary, this application includes at least one of the following beneficial technical effects: 1. This application activates bamboo fiber with sodium hydroxide, destroying the hydrogen bond network and crystal structure of the cellulose molecular chain, exposing its internal hydroxyl groups. Then, the activated bamboo fiber is reacted with sodium chloroacetate under alkaline conditions to carboxymethylate the bamboo fiber, improving its hydrophilicity and wettability. Then, excess acid is added to the reaction system to convert the water-soluble sodium carboxylate into free carboxylic acid, while washing away excess sodium hydroxide and salts, resulting in pure modified fiber. Finally, the carboxymethyl modified bamboo fiber is mixed and dispersed with unmodified bamboo fiber, and a cationic polyester wet strength agent is added to form a water-resistant covalent cross-linked network between the fibers. The paper is then formed and dried to obtain carboxymethyl modified bamboo fiber conductive paper. The obtained carboxymethyl modified bamboo fiber conductive paper maintains good conductivity while ensuring the necessary tensile strength. 2. In this application, the mass ratio of sodium chloroacetate to the cellulose hydroxyl groups in the activated bamboo fiber is set in the range of 0.8-1:2-2.2. The resulting carboxymethyl modified bamboo fiber has an ideal degree of carboxymethyl substitution and Zeta potential. When the mass ratio of sodium chloroacetate is too large, the excess sodium chloroacetate will cause the bamboo fiber to have an extremely high degree of substitution, making the bamboo fiber prone to excessive water absorption and swelling, and unable to shrink back after drying. This will reduce the wet tensile strength and conductivity of the carboxymethyl modified bamboo fiber conductive paper. When the mass ratio of sodium chloroacetate is too small, sodium chloroacetate cannot fully replace the hydroxyl groups of cellulose, which will reduce the hydrophilicity of the carboxymethyl modified bamboo fiber conductive paper. 3. This application also adds sulfonated lignin, which contains hydrophilic sulfonic acid groups, which can synergistically enhance the hydrophilicity of the system with carboxymethyl groups and improve the conductivity of carboxymethyl modified bamboo fiber. Sulfonated lignin can also combine sulfonic acid groups and carboxymethyl groups with cationic polyester wet strength agent through ionic bonds to form a three-dimensional cross-linking bridge of "fiber-lignin-wet strength agent", which improves the adsorption efficiency of cationic polyester wet strength agent on the fiber surface and improves the wet tensile strength of carboxymethyl modified bamboo fiber. Detailed Implementation

[0028] The raw materials in this application include the following: Bamboo strips: Bamboo strips from Leshan Huasen Forestry Development Co., Ltd. are used; Sodium chloroacetate: Uses a commercially available product with CAS number 3926-62-3; Cationic polyester wet strength agent: commercially available product with brand name XLK1205 is used; Sulfonated lignin: Commercially available products from Hubei Maidehao Biotechnology Co., Ltd.

[0029] Preparation Example 1 The method for preparing bamboo fiber includes the following steps: Pre-treatment: Wash and dry the bamboo strips, and cut them into smaller sizes; Crushing and twisting: The bamboo strips are repeatedly crushed and rubbed using a machine with toothed rollers. Mechanical force is used to de-fiber the bamboo strips, causing them to "separate the bone and flesh" to obtain a mesh-like bamboo fiber. Opening and drying: The kneaded fibers are opened, combed, and finally dried to obtain bamboo fiber.

[0030] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0031] Example 1 A method for preparing carboxymethyl modified bamboo fiber diversion paper includes the following steps: S1. Bamboo fiber with a dry weight of 24g was immersed in 18wt% sodium hydroxide and activated for 4h to obtain an activated system containing activated bamboo fiber. S2. Sodium chloroacetate was added to the activation system containing activated bamboo fiber to carry out the reaction at a temperature of 60°C for 3 hours to obtain carboxymethylated bamboo fiber. S3. Add excess citric acid to carboxymethylated bamboo fiber, and after the reaction is complete, wash until neutral and test to find no chloride ion residue to obtain carboxymethyl modified bamboo fiber. S4. After mixing and dispersing carboxymethyl modified bamboo fiber with unmodified bamboo fiber, the mixture is formed into a preliminary bamboo fiber guide paper. Then, a cationic polyester wet strength agent with a concentration of 1 wt% is sprayed on the surface of the preliminary bamboo fiber guide paper. After drying, the carboxymethyl modified bamboo fiber guide paper is obtained.

[0032] The mass ratio of sodium chloroacetate to cellulose hydroxyl groups in activated bamboo fiber is 1:2, the cationic polyester wet strength agent is 1.5% of the mass of carboxymethyl modified bamboo fiber, and the unmodified bamboo fiber accounts for 50% of the total mass of carboxymethyl modified bamboo fiber and unmodified bamboo fiber.

[0033] Comparative Example 1 Comparative Example 1, based on the preparation method of Example 1, directly formed unmodified bamboo fiber into paper and dried it to obtain bamboo fiber guiding paper.

[0034] Comparative Example 2 Comparative Example 2, based on the preparation method of Example 1, involves washing the carboxymethylated bamboo fiber with water in S3 until the washing solution is neutral.

[0035] Performance testing The bamboo fiber diversion paper of Example 1 and Comparative Examples 1-2 were analyzed, and the specific testing methods are as follows: 1. Tensile strength According to GB / T 12914.1-2023 standard, using an electronic tensile testing machine, a 15mm×180mm specimen that has been pre-balanced (23℃, 50% RH, ≥4h) is stretched at a constant speed of 10mm / min (clamping distance 100mm), and the maximum force value F_max (N) is recorded. The dry tensile strength is calculated according to the formula: Dry tensile strength = F_max / 0.015 (kN / m); the wet test is completed within 60 seconds after immersion in water using the same testing method.

[0036] 2. Porosity The solid specific surface area (V) was determined by the gas adsorption BET method according to ISO 9277:2022, and the true density (ρ-true) was determined by the helium specific gravity bottle method according to ISO 12154. Therefore, the skeletal volume of 1g of bamboo fiber is deduced as: V-solid = 1 / ρ-true (cm³). 3The total volume of 1 gram of material is: V-total=V-solid+V-pore, thus the porosity (%) is obtained as (V-pore / V-total)×100%.

[0037] 3. Flow diversion efficiency Using the constant pressure differential breakthrough method, under 1.0 kPa hydraulic pressure and 23℃ conditions, 0.1 mL of 0.9% NaCl solution was vertically passed through a 1 cm channel. 2 The effective area of ​​carboxymethyl modified bamboo fiber diffusing paper was measured, and the time required for complete penetration was determined.

[0038] Based on the above detection method, the detection results of Example 1 and Comparative Examples 1-2 were obtained.

[0039] Table 1 Performance test results for Example 1 and Comparative Examples 1-2 Referring to Table 1, comparing Example 1 and Comparative Example 1, it can be seen that the introduction of carboxymethyl groups can significantly improve the hydrophilicity and porosity of bamboo fibers. This may be because the introduction of carboxymethyl groups can increase the spacing between bamboo fiber molecular chains, significantly reduce the physical entanglement between bamboo fibers, and in aqueous solution, these negatively charged groups will repel each other, absorbing a large number of water molecules into the interior of bamboo fibers, causing the bamboo fibers to swell, thereby opening up the micropores and channels inside the bamboo fibers and increasing the porosity of bamboo fibers.

[0040] Comparing Example 1 and Comparative Example 2, it can be seen that the performance of the carboxymethyl modified bamboo fiber drainage paper in Example 1 is significantly better than that in Comparative Example 2. This may be because the addition of excess acid not only adjusts the pH to neutral, but the hydrogen ions in the acid can also react with the sodium carboxylate salt, displacing Na+. + It is then converted into carboxylic acid groups, and the free Na is removed through multiple washes. + Thorough washing removes sodium salt residue, thereby improving the tensile strength and flow efficiency of carboxymethyl modified bamboo fiber conductive paper.

[0041] Example 2-3 In Examples 2-3, the mass ratio of sodium chloroacetate to cellulose hydroxyl groups in activated bamboo fiber was adjusted based on the preparation method in Example 1. The specific adjustments are shown in Table 2.

[0042] Comparative Examples 3-4 Comparative Examples 3-4 were prepared based on the method in Example 1, but the mass ratio of sodium chloroacetate to cellulose hydroxyl groups in the activated bamboo fiber was adjusted as shown in Table 2.

[0043] Table 2. Mass ratio of sodium chloroacetate to cellulose hydroxyl groups in activated bamboo fiber in Examples 1-3 and Comparative Examples 3-4, and performance test results. Referring to Table 2, comparing Examples 1-3 and Comparative Examples 3-4, it can be seen that when the mass ratio of sodium chloroacetate to the cellulose hydroxyl groups in the activated bamboo fiber is 0.8-1:2-2.2, especially when the mass ratio of sodium chloroacetate to the cellulose hydroxyl groups in the activated bamboo fiber is 1:2, the resulting carboxymethyl modified bamboo fiber conductive paper exhibits the best performance. This may be because when the proportion of sodium chloroacetate is too high, the excessive sodium chloroacetate will cause the bamboo fiber to have an extremely high degree of substitution, making the bamboo fiber prone to excessive water absorption and swelling, and unable to shrink back after drying, resulting in a decrease in the wet tensile strength and conductive efficiency of the carboxymethyl modified bamboo fiber conductive paper. When the mass ratio of sodium chloroacetate is too low, the amount of sodium chloroacetate added is insufficient, and it cannot fully channel the cellulose hydroxyl groups, resulting in a decrease in the hydrophilicity of the carboxymethyl modified bamboo fiber conductive paper.

[0044] Examples 4-7 Examples 4-7 are based on the preparation method of Example 1, but the concentration of the cationic polyester wet strength agent is adjusted, as shown in Table 3.

[0045] The carboxymethyl modified bamboo fiber diffusing paper of Examples 4-7 was subjected to the above-mentioned performance tests, and the test results are shown in Table 3.

[0046] Table 3. Degree of carboxymethyl substitution and performance test results for Examples 1 and 4-7 Referring to Table 3, a comparison of Examples 1 and 4-7 shows that when the concentration of the cationic polyester wet strength agent is in the range of 0.2-2 wt%, especially when the concentration of the cationic polyester wet strength agent is 1 wt%, the resulting carboxymethyl modified bamboo fiber guide paper exhibits the best performance. This may be because when the concentration of the cationic polyester wet strength agent is too low, the cationic polyester wet strength agent molecules cannot form a sufficient number of cross-linking networks between the fibers, resulting in a decrease in the tensile strength of the carboxymethyl modified bamboo fiber guide paper. When the concentration of the cationic polyester wet strength agent is too high, after the negative charge on the fiber surface is completely neutralized, the excess cationic polyester wet strength agent will cause its surface charge to reverse from negative to positive, resulting in strong electrostatic attraction between the fibers, which reduces the tensile strength of the carboxymethyl modified bamboo fiber guide paper. Furthermore, excessive cationic polyester wet strength agent will cause excessive cross-linking between the fibers, resulting in an increase in the hardness of the carboxymethyl modified bamboo fiber guide paper.

[0047] Examples 8-11 Examples 8-11 are based on the preparation method of Example 1, but the proportion of carboxymethyl modified bamboo fiber as cationic polyester wet strength agent is adjusted, as shown in Table 3.

[0048] The carboxymethyl modified bamboo fiber guide paper of Examples 8-11 was subjected to the above-mentioned performance tests, and the test results are shown in Table 4.

[0049] Table 4. Proportion of carboxymethyl modified bamboo fiber as cationic polyester wet strength agent in Examples 1 and 8-11, and corresponding performance test results. Referring to Table 4, a comparison of Examples 1 and 8-11 shows that when the cationic polyester wet strength agent is 1-2% of the mass of carboxymethyl modified bamboo fiber, especially when the cationic polyester wet strength agent is 1.5% of the mass of carboxymethyl modified bamboo fiber, the resulting carboxymethyl modified bamboo fiber conductive paper exhibits the best performance. This may be because when the proportion of cationic polyester wet strength agent is too high, the excessive cationic polyester wet strength agent will coat the hydrophilic groups of carboxymethyl modified bamboo fiber and block the pores, severely weakening the conductive performance, and at the same time causing a decrease in the dry tensile strength of the carboxymethyl modified bamboo fiber conductive paper; when the proportion of cationic polyester wet strength agent is too low, the cationic polyester wet strength agent is insufficient to cover the highly negatively charged surface of carboxymethyl modified fiber, making it difficult to form an effective water-resistant cross-linking network, resulting in insufficient wet tensile strength, loose fiber bonding when exposed to liquid, easy collapse of the paper structure, and loss of functionality.

[0050] Example 12 Example 12, based on the preparation method of Example 1, further includes the addition of sulfonated lignin in step S4. After mixing and dispersing sulfonated lignin, carboxymethyl modified bamboo fiber, and unmodified bamboo fiber, a cationic polyester wet strength agent is added for paper forming. After drying, carboxymethyl modified bamboo fiber guide paper is obtained. The amount of sulfonated lignin added is 3% of the oven-dry fiber mass (total mass of oven-dry modified bamboo fiber and oven-dry unmodified bamboo fiber).

[0051] Examples 13-16 Examples 13-16 are based on the preparation method of Example 8, but the amount of sulfonated lignin added is adjusted, as shown in Table 5.

[0052] The carboxymethyl modified bamboo fiber diffusing paper of Examples 12-16 was subjected to the above-mentioned performance tests, and the test results are shown in Table 5.

[0053] Table 5. Sulfonated lignin addition amount and performance test results for Examples 1 and 12-16 Referring to Table 5, a comparison of Examples 1 and 12-16 shows that the addition of sulfonated lignin can improve the performance of carboxymethyl modified bamboo fiber conductive paper. This may be because sulfonated lignin contains hydrophilic sulfonic acid groups, which can synergistically enhance the hydrophilicity of the system with carboxymethyl groups, thereby increasing the conductivity of carboxymethyl modified bamboo fiber. Furthermore, sulfonated lignin can also bind sulfonic acid groups and carboxymethyl groups simultaneously with cationic polyester wet strength agent through ionic bonds, forming a three-dimensional cross-linking bridge of "fiber-lignin-wet strength agent", which improves the adsorption efficiency of cationic polyester wet strength agent on the fiber surface and increases the wet tensile strength of carboxymethyl modified bamboo fiber.

[0054] Comparative examples 12-16 show that when the amount of sulfonated lignin added is 1-5% of the oven-dry fiber mass, especially when the amount of sulfonated lignin added is 3% of the oven-dry fiber mass, the resulting carboxymethyl modified bamboo fiber conductive paper exhibits the best performance. This may be because when the amount of sulfonated lignin added is too low, the fiber dispersion is insufficient, and the unmodified bamboo fiber and carboxymethyl modified fiber are prone to flocculation, resulting in poor paper uniformity and fluctuating conductive performance. Furthermore, the cationic polyester wet strength agent is difficult to effectively crosslink due to insufficient charge shielding, resulting in limited improvement in wet tensile strength. When the amount of sulfonated lignin added is too high, the excessive anionic sulfonic acid groups will severely hinder the adsorption and crosslinking of the subsequent cationic polyester wet strength agent, significantly weakening the wet strength. At the same time, lignin aggregation blocks fiber pores and covers hydrophilic groups, reducing conductive efficiency.

[0055] Examples 17-20 Examples 17-20 are based on the preparation method of Example 1, but the ratio of the mass of unmodified bamboo fiber to the total fiber mass (total mass of carboxymethyl modified bamboo fiber and unmodified bamboo fiber) is adjusted as shown in Table 6.

[0056] The carboxymethyl modified bamboo fiber diffusing paper of Examples 17-20 was subjected to the above-mentioned performance tests, and the test results are shown in Table 6.

[0057] Table 6. Ratio of unmodified bamboo fiber to total fiber mass and performance test results for Examples 1 and 17-20 Referring to Table 6, a comparison of Examples 1 and 17-20 shows that when the proportion of unmodified bamboo fiber is large, the unmodified bamboo fiber can serve as a high-strength skeleton support, ensuring the mechanical strength of the carboxymethyl modified bamboo fiber guiding paper. However, when the proportion of carboxymethyl modified bamboo fiber is small, the hydrophilicity of the carboxymethyl modified bamboo fiber is insufficient, resulting in a decrease in guiding efficiency. When the proportion of unmodified bamboo fiber is small, the mechanical strength of the carboxymethyl modified bamboo fiber guiding paper is not ideal, and excessive carboxymethyl modified bamboo fiber will lead to uneven pore structure, local blockage of water channels, and a decrease in overall guiding efficiency.

[0058] Application Example 1 The carboxymethyl modified bamboo fiber guide paper from Example 1 was cut into a shape that matched the size of the filtration equipment. Two to four layers of the cut carboxymethyl modified bamboo fiber guide paper were then stacked to form a filter unit. The edges of the carboxymethyl modified bamboo fiber guide paper were sealed using a hot-press bonding process. The filter unit was then assembled onto the filter membrane support of the filtration equipment. The filter paper was securely connected to the support using bolts or snap-fit ​​connections. The water to be treated was then pressurized (0.1-0.3 MPa) or allowed to flow through the filter unit by gravity, thus achieving filtration of the water. The removal rates of humic substances, E. coli, and lead ions were compared between the treated water and the water after treatment.

[0059] Comparative Example 5 The polyethersulfone filter membrane is assembled on the filter membrane support of the filtration equipment. The filter paper is securely connected to the support by means of bolts or snap-fit ​​connections. The water to be treated is flowed through the filtration unit under pressure (0.1-0.3MPa) to achieve filtration of the water to be treated. The removal rate of humic substances, the retention rate of E. coli and the removal rate of lead ions are obtained by comparing the water to be treated and the treated water.

[0060] Performance testing: The water filtered by the filtration units of Application Example 1 and Comparative Example 5 was analyzed using the following specific testing methods: 1. Humic acid removal rate The absorbance A0 of the humic substances in the water to be treated and the absorbance A1 of the humic substances in the treated water were measured at 245 nm using a UV spectrophotometer. The humic substance removal rate was calculated as follows: Humic substance removal rate (%) = [(A0-A1) / A0] × 100%.

[0061] 2. E. coli retention rate Collect water samples to be treated and water samples after treatment, and dilute the water samples to be treated and water samples after treatment. Obtain the number of E. coli in the water to be treated and the number of E. coli in the water after treatment by bacterial culture technology. The E. coli retention rate (%) = [1 - (number of E. coli in the water after treatment / number of E. coli in the water to be treated)] × 100%.

[0062] 3. Lead ion removal rate Prepare an aqueous solution containing 10 mg / L of lead ions. After filtering the aqueous solution through a filtration unit, the concentration of lead ions in the treated water is measured. The lead ion removal rate (%) = [(10 - concentration of lead ions in the treated water) / 10] × 100%.

[0063] The effects of the filter units in application example 1 and comparative example 5 on water filtration were obtained based on the above testing methods.

[0064] Table 7 shows the water filtration effects of Application Example 1 and Comparative Example 5. Referring to Table 7, a comparison of Application Example 1 and Comparative Example 5 shows that the filter unit prepared from carboxymethyl modified bamboo fiber guide paper has a better effect in water treatment applications. This may be because the negative charge brought by the carboxymethyl groups on the surface of the filter unit prepared from carboxymethyl modified bamboo fiber can electrostatically adsorb positively charged pollutants in the water.

[0065] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing carboxymethyl modified bamboo fiber diversion paper, characterized in that, Includes the following steps: S1. Bamboo fibers are activated by immersing them in sodium hydroxide to obtain an activated system containing activated bamboo fibers; S2. Sodium chloroacetate is added to the activation system containing activated bamboo fiber to carry out the reaction at a temperature of 50-70℃ for 2-4 hours to obtain carboxymethylated bamboo fiber. S3. Add excess acid to carboxymethylated bamboo fiber, and after the reaction is complete, wash until neutral and detect no chloride ion residue to obtain carboxymethyl modified bamboo fiber. S4. After mixing and dispersing carboxymethyl modified bamboo fiber with unmodified bamboo fiber, the mixture is formed into a preliminary bamboo fiber guide paper. Then, a cationic polyester wet strength agent is sprayed onto the surface of the preliminary bamboo fiber guide paper, and after drying, the carboxymethyl modified bamboo fiber guide paper is obtained.

2. The method for preparing carboxymethyl modified bamboo fiber diversion paper according to claim 1, characterized in that, In S2, the mass ratio of sodium chloroacetate to the cellulose hydroxyl groups in the activated bamboo fiber is 0.8-1:2-2.

2.

3. The method for preparing carboxymethyl modified bamboo fiber diversion paper according to claim 1, characterized in that, The concentration of the cationic polyester wet strength agent is 0.2-2 wt%.

4. The method for preparing carboxymethyl modified bamboo fiber diversion paper according to claim 3, characterized in that, The cationic polyester wet strength agent is (1-2%) of the mass of carboxymethyl modified bamboo fiber.

5. The method for preparing carboxymethyl modified bamboo fiber diversion paper according to claim 1, characterized in that, In S4, sulfonated lignin is also added. After mixing and dispersing sulfonated lignin, carboxymethyl modified bamboo fiber and unmodified bamboo fiber, the mixture is formed into a preliminary bamboo fiber guide paper. Then, cationic polyester wet strength agent is sprayed on the surface of the preliminary bamboo fiber guide paper and dried to obtain carboxymethyl modified bamboo fiber guide paper.

6. The method for preparing carboxymethyl modified bamboo fiber diversion paper according to claim 5, characterized in that, The amount of sulfonated lignin added is 1-5% of the total mass of oven-dried modified bamboo fiber and oven-dried unmodified bamboo fiber.

7. The method for preparing carboxymethyl modified bamboo fiber diversion paper according to claim 1, characterized in that, The unmodified bamboo fiber accounts for 20-80% of the total mass of carboxymethyl modified bamboo fiber and unmodified bamboo fiber.

8. A carboxymethyl modified bamboo fiber diversion paper, characterized in that, It is prepared by the method of any one of claims 1-7 for preparing carboxymethyl modified bamboo fiber diverting paper.

9. An application of a carboxymethyl modified bamboo fiber diversion paper, characterized in that, The application of the carboxymethyl modified bamboo fiber guide paper as described in claim 8 in water filtration.

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