Preparation process and application of cross-linked sodium carboxymethyl cellulose from bamboo

Abstract

The application relates to the technical field of cross-linked sodium carboxymethyl cellulose, in particular to a preparation process and application of bamboo-source cross-linked sodium carboxymethyl cellulose. The preparation process comprises preliminary alkalization, secondary alkalization, etherification and cross-linking, and does not use alcohol as a solvent, so that production cost can be effectively reduced, the safety hidden danger of alcohol solvent storage and use is reduced, and the production process is more green and environmentally friendly. In addition, the application can save the step of neutralizing the material after etherification and before cross-linking, avoids the addition of acid to reduce the acidolysis of the bamboo-source cross-linked sodium carboxymethyl cellulose, and improves the production efficiency and yield of the bamboo-source cross-linked sodium carboxymethyl cellulose to a certain extent. The cross-linked sodium carboxymethyl cellulose prepared by the application has more fiber sources, lower cost, greater bonding strength between fibers, and a porous structure, and has a wider application in the fields of textiles, food, medicines, electronic equipment, industrial equipment and the like.

Description

Technical Field

[0001] This application relates to the field of cross-linked carboxymethyl cellulose sodium technology, and more specifically, to a preparation process and application of bamboo-derived cross-linked carboxymethyl cellulose sodium. Background Technology

[0002] Bamboo fiber, primarily derived from naturally grown bamboo, is a macromolecular polysaccharide composed of D-glucose linked by β-1,4 glycosidic bonds. It possesses excellent air permeability, instant water absorption, strong abrasion resistance, and good dyeability. It also exhibits natural antibacterial, bacteriostatic, mite-repellent, deodorizing, and UV-resistant properties. Compared to wood fiber, bamboo fiber has a higher aspect ratio and specific surface area, stronger fiber entanglement and interweaving, greater fiber bonding strength, and a porous structure, thus offering better application prospects.

[0003] Bamboo-derived crosslinked carboxymethyl cellulose sodium is mainly obtained from bamboo cellulose as raw material, which is crosslinked with a crosslinking agent after alkalization and etherification. In the existing process, bamboo cellulose is directly dispersed in an aqueous solution of industrial alcohol or other alcohols, and then a high-concentration sodium hydroxide solution is added for alkalization. The alcohol-water solution is used to wet the bamboo cellulose and also because acid is needed for neutralization after the subsequent etherification step. Cellulose is alkali-resistant but not acid-resistant, which affects the structural integrity of the cellulose. In addition, alcohol solvents are expensive and flammable and explosive, which greatly increases production costs and safety issues in actual industrial production. Summary of the Invention

[0004] This application provides a preparation process and application of bamboo-derived crosslinked carboxymethyl cellulose sodium, which does not use alcohol as a solvent. This not only effectively reduces production costs and minimizes the safety hazards of using and / or storing alcohol solvents, but also makes the production process more green and environmentally friendly. In addition, it can eliminate the "neutralization" step after etherification and before crosslinking, avoiding the addition of acid to reduce the acid hydrolysis of bamboo-derived crosslinked carboxymethyl cellulose sodium, thereby improving the production efficiency and yield of bamboo-derived crosslinked carboxymethyl cellulose sodium to a certain extent.

[0005] In a first aspect, this application provides a process for preparing bamboo-derived crosslinked carboxymethyl cellulose sodium, comprising the following steps: preliminary alkalization: bamboo cellulose is dispersed in a sodium hydroxide solution with a concentration of 1-3 wt% for preliminary alkalization, and the preliminary alkalized bamboo cellulose is obtained after draining the sodium hydroxide solution;

[0006] Secondary alkalization: The initially alkalized bamboo cellulose is dispersed in a sodium hydroxide solution with a concentration of 30-45 wt% for secondary alkalization to obtain an alkali cellulose mixture;

[0007] Etherification: Sodium chloroacetate is added to the alkali cellulose mixture to etherify it, thereby obtaining an etherified cellulose mixture;

[0008] Crosslinking: A crosslinking agent is added to the etherified cellulose mixture. After the etherified cellulose in the etherified cellulose mixture and the crosslinking agent have completed crosslinking, the mixture is washed with water multiple times until no precipitation occurs in the waste liquid and silver nitrate solution, and bamboo-sourced crosslinked carboxymethyl cellulose sodium is harvested.

[0009] By employing the above-mentioned technical solution, compared to wood cellulose, bamboo pulp natural cellulose exhibits stronger intramolecular and intermolecular hydrogen bonds, aggregating in the solid state to form different fibrillary structures and constituting highly crystalline cellulose fibers in a multi-layered spiral manner. This structure confines a large number of reactive groups within the crystalline regions, making them difficult for various reagents to access, severely affecting the rate and uniformity of the cellulose carboxymethylation reaction, especially in heterogeneous reactions. Therefore, this application employs "low-alkali" activation to disrupt the crystalline regions of cellulose, improve wettability, increase the accessibility of hydroxyl groups in the reaction, and thus accelerate the entire reaction process.

[0010] In addition, since bamboo cellulose usually contains some lignin, this application first uses a low-concentration (1-3wt%) sodium hydroxide solution to further degrade and remove the lignin in the bamboo cellulose. Since the sodium hydroxide solution has a low alkali content, even if the lignin dissolves in the sodium hydroxide solution, the viscosity of the system will not change significantly. At this time, the alkali in the system can better wet the porous bamboo cellulose interface for preliminary alkalization.

[0011] After the bamboo cellulose has completed its initial alkalization, it is dispersed in a high-concentration (30-45wt%) sodium hydroxide solution for further alkalization. Since a large amount of lignin has been removed during the initial alkalization, and the bamboo cellulose has been soaked in a low-concentration sodium hydroxide solution, the high-concentration alkali can quickly fill the porous structure interface of the bamboo cellulose and deeply alkalize it, thereby effectively improving the alkalization effect of the bamboo cellulose.

[0012] Based on this, sodium chloroacetate is added to the harvested alkali cellulose mixture. Sodium chloroacetate first reacts with sodium hydroxide in the alkali cellulose mixture to produce sodium chloroacetate and water. Sodium chloroacetate then reacts with alkali cellulose to produce sodium carboxymethyl cellulose, thus completing the etherification reaction. After etherification, some sodium hydroxide remains in the system. Excess sodium chloroacetate can directly react with sodium hydroxide to produce sodium glycolate, thereby reducing the hydrolysis of sodium chloroacetate to glycolic acid and minimizing its impact on the structural morphology of the etherified cellulose, further improving product purity and structural strength.

[0013] In the subsequent crosslinking process, this application did not perform acid neutralization treatment. This is because bamboo cellulose has fewer impurities (mainly sodium chloride and sodium glycolate) after the previous alkalization and etherification treatments. At this time, the system remains alkaline because the sodium hydroxide solution has not been removed. The etherified cellulose obtained after etherification (i.e., sodium carboxymethyl cellulose, CMC) is alkali-resistant but not acid-resistant. Therefore, etherified cellulose can effectively reduce degradation and maintain its structural morphology better in this alkaline system. Moreover, the crosslinked bamboo-derived crosslinked sodium carboxymethyl cellulose is insoluble in sodium hydroxide solution, and residual sodium hydroxide, sodium glycolate, crosslinking agent, etc. can be removed simply by multiple water washings. In this application, if fibrous bamboo cellulose is used, the final bamboo-derived sodium carboxymethyl cellulose can also maintain the fiber morphology well; if powdered bamboo cellulose is used, the final bamboo-derived sodium carboxymethyl cellulose will be in powder form.

[0014] Therefore, this application eliminates the use of alcohol through the "preliminary alkalization-secondary alkalization" operation, and also eliminates the "acid neutralization" step in subsequent operations. This not only improves the alkalization effect of bamboo cellulose, but also effectively reduces production costs, reduces the safety hazards of using and / or storing alcohol solvents, makes the production process more green and environmentally friendly, and improves the production efficiency of bamboo-derived crosslinked carboxymethyl cellulose sodium.

[0015] Preferably, in the preliminary alkalization step, the weight ratio of the bamboo cellulose to the sodium hydroxide solution is 1:1-5.

[0016] By adopting the above technical solution, if the amount of sodium hydroxide solution is small, it is difficult for the bamboo cellulose to be completely submerged. The lignin in the bamboo cellulose dissolved in the sodium hydroxide solution will still interfere with the wetting effect and the corresponding alkalization effect to a certain extent. If the amount of sodium hydroxide solution is large, it will lead to an increase in the cost of alkalization. Therefore, a weight ratio of 1:1-5 is more appropriate.

[0017] Preferably, in the step of re-alkalization, the weight ratio of bamboo cellulose in the initially alkalized bamboo cellulose to the sodium hydroxide solution is 6-8:100.

[0018] By adopting the above technical solution, the sodium hydroxide solution that is alkalized again is not only to provide alkalization raw materials, but also to provide a buffer system for the subsequent etherification and crosslinking of bamboo cellulose. The amount of sodium hydroxide solution used in the above weight ratio can ensure that the bamboo cellulose flows well in the system, thereby allowing the reaction to proceed fully.

[0019] Preferably, the bamboo cellulose is initially alkalized at a temperature of 15-35℃ for 0.5-3 hours, and the initially alkalized bamboo cellulose is then alkalized again at a temperature of 15-35℃ for 0.5-3 hours.

[0020] By adopting the above technical solution, the degree of fiber alkalization is correlated with the concentration of sodium hydroxide solution, alkalization temperature, and alkalization time. Higher sodium hydroxide concentrations, higher alkalization temperatures, and longer alkalization times result in faster alkalization efficiency, but can also cause yellowing or even degradation of the fibers. Therefore, this application designs two suitable concentrations of sodium hydroxide solution. To match the sodium hydroxide solution concentration, this application preferably performs alkalization at a temperature of 15-35℃, and the alkalization time can be adjusted within the range of 0.5-3 hours as needed.

[0021] Preferably, in the etherification step, the amount of sodium chloroacetate added is 0.5-1 times that of the bamboo cellulose.

[0022] By adopting the above technical solution, excessive use of sodium chloroacetate can easily lead to excessive cross-linking in the subsequent process, resulting in poor cellulose solubility and poor overall product performance; if the amount of sodium chloroacetate is too small, the cellulose is prone to insufficient cross-linking in the subsequent process, resulting in excessive water solubility of the product, which may lead to dissolution or the formation of colloids. Therefore, the above weight ratio is appropriate in the sodium hydroxide solution system of this application.

[0023] Preferably, in the crosslinking step, the weight ratio of the crosslinking agent to the etherified cellulose mixture is 1-10:100.

[0024] By adopting the above technical solution, if the amount of crosslinking agent is too low, the crosslinking of etherified cellulose may be incomplete, while excessive crosslinking agent is prone to side reactions that produce impurities such as chlorides, and will also leave too much crosslinking agent in the system, increasing the difficulty of subsequent washing. The above weight ratio of this application can effectively prepare crosslinked carboxymethyl cellulose sodium that meets national standards.

[0025] Preferably, in the etherification step, the reaction is controlled at a temperature of 50-70°C for 0.5-3 hours; in the crosslinking step, the reaction is controlled at a temperature of 60-70°C for 1-8 hours.

[0026] By employing the above technical solution, the etherification reaction of alkali cellulose with sodium chloroacetate is a complex chemical reaction, including the neutralization reaction of sodium chloroacetate with sodium hydroxide and the nucleophilic substitution reaction of sodium chloroacetate (formed through the former neutralization reaction) with alkali cellulose. The former is an exothermic reaction, while the latter requires an energy donation to dissociate sodium chloroacetate into high-energy positive ions that react with alkali cellulose to form ethers. Therefore, the reaction system requires a certain high-temperature etherification, and subsequent crosslinking also requires heat to maintain the reaction. However, bamboo cellulose is prone to degradation in a strong alkaline system (sodium hydroxide) at excessively high temperatures. Therefore, this application strictly controls the etherification temperature and crosslinking temperature. Under the above reaction conditions, crosslinked sodium carboxymethyl cellulose with higher yield and degree of substitution can be obtained.

[0027] Preferably, in the crosslinking step, the crosslinking agent is epichlorohydrin.

[0028] By adopting the above technical solution, since the system maintains alkalinity during etherification, there is a lack of catalytic effect of glycolic acid on etherified cellulose. Therefore, this application utilizes the characteristics of epichlorohydrin's fast crosslinking speed and high reactivity to fully complete the crosslinking reaction with etherified cellulose, further ensuring the yield and purity of bamboo-derived crosslinked carboxymethyl cellulose sodium.

[0029] Preferably, in the preliminary alkalization and re-alkalization steps, the sodium hydroxide solution is a sodium hydroxide solution.

[0030] By adopting the above technical solution, sodium hydroxide is a common alkali with wide availability and good alkalization effect on cellulose, so it is preferred as a further option.

[0031] Secondly, this application provides a bamboo-derived cross-linked carboxymethyl cellulose sodium, which is prepared using the above-mentioned preparation process. This bamboo-derived cross-linked carboxymethyl cellulose sodium meets national standards and has the characteristics of green and environmentally friendly production process, low production cost, and high production efficiency.

[0032] Thirdly, this application provides applications of bamboo-derived crosslinked carboxymethyl cellulose sodium. Compared with wood-derived crosslinked carboxymethyl cellulose sodium, the bamboo-derived crosslinked carboxymethyl cellulose sodium prepared in this application has a stronger bond strength between fibers and a porous structure, which has a wider range of applications in the fields of textiles, food, pharmaceuticals, electronic equipment, and industrial equipment.

[0033] In summary, this application has the following beneficial effects:

[0034] 1. This application eliminates the use of alcohol through the "preliminary alkalization-secondary alkalization" operation, and also eliminates the "acid neutralization" step in subsequent operations. This not only improves the alkalization effect of bamboo cellulose, but also effectively reduces production costs, reduces the safety hazards of using and / or storing alcohol solvents, makes the production process more green and environmentally friendly, and improves the production efficiency and yield of bamboo-derived crosslinked carboxymethyl cellulose sodium.

[0035] 2. This application limits the amount of sodium hydroxide solution used according to the intended use of each solution, thereby further improving the alkalization effect of bamboo cellulose and laying a good foundation for subsequent etherification and crosslinking.

[0036] 3. This application achieves the production of cross-linked sodium carboxymethyl cellulose that meets national standards by strictly controlling the parameters of alkalization, etherification, and cross-linking, thus eliminating the need for alcohol solution and neutralization processes. Compared with wood-derived cross-linked sodium carboxymethyl cellulose, it has a wider range of fiber sources, lower cost, and stronger bonding between fibers. It also has a porous structure, making it more widely applicable in the fields of textiles, food, pharmaceuticals, electronic equipment, and industrial equipment. Attached Figure Description

[0037] Figure 1 This is a partial sample image of the self-made fibrous bamboo cellulose from Example 1 of this application;

[0038] Figure 2 This is a partial sample image of bamboo-derived crosslinked sodium carboxymethyl cellulose from Example 1 of this application;

[0039] Figure 3 This is a scanning electron microscope image of bamboo-derived crosslinked sodium carboxymethyl cellulose from Example 1 of this application;

[0040] Figure 4 This is a partial sample image of bamboo-derived crosslinked sodium carboxymethyl cellulose from Example 6 of this application. Detailed Implementation

[0041] The raw materials in this application include the following:

[0042] Bamboo cellulose: The experiment was conducted using self-made fibrous bamboo cellulose as an example, and the experiment was conducted using commercially available bamboo fiber powder with an effective ingredient content of ≥98% and a particle size of 20-100 mesh as an example.

[0043] Wood cellulose: Commercially available powdered wood cellulose with a particle size of 20-100 mesh was used as an example for the experiment;

[0044] Cotton linters: Commercially available linter series are used, with a moisture regain of ≤8.5%, a micronaire value of Grade A, a fiber length of 13mm, and an impurity content of ≤3%;

[0045] Sodium hydroxide: Commercially available product with CAS number 1310-73-2 and purity ≥99%;

[0046] Sodium chloroacetate: CAS No. 79-11-8, commercially available product with a purity ≥99%;

[0047] Crosslinking agents: Taking epichlorohydrin (CAS No. 106-89-8), sodium chromate (CAS No. 7775-11-3), and sodium sulfite (CAS No. 7757-83-7) as examples, their purity is ≥99%.

[0048] The present application will be further described in detail below with reference to the accompanying drawings, embodiments and comparative examples.

[0049] Example

[0050] Example 1

[0051] A process for preparing bamboo-derived crosslinked carboxymethyl cellulose sodium includes the following steps:

[0052] Raw material preparation: Take 2.00 kg of oven-dry bamboo strips and cut them into pieces 30-40 cm long and 2-3 cm wide. Soak them in distilled water for 12 hours, then place them in a digester. Pulp preparation is performed using the sulfate process. The digestion process is as follows: use 20% alkali (as NaOH), 20% sulfidation (as Na2S), and a liquor ratio of 1:4. Gradually increase the temperature to 170℃ over 2 hours and then maintain the temperature for another 2 hours. After digestion, wash the resulting bamboo pulp with distilled water, filter it through a 0.15 mm sieve to remove impurities, and then dry it to obtain bamboo cellulose (see [link to relevant documentation]). Figure 1 );

[0053] Preliminary alkalization: Take 1.00 kg of bamboo cellulose and disperse it in 4.00 kg of sodium hydroxide solution with a concentration of 2 wt%, that is, the weight ratio of bamboo cellulose to sodium hydroxide solution is 1:3. Control the temperature at 20℃ for preliminary alkalization for 1.5 h. Drain the sodium hydroxide solution through a flat sieve with a sieve opening of 0.15 mm (until no more dripping occurs) to obtain 1.41 kg of preliminary alkalization bamboo cellulose.

[0054] Secondary alkalization: The initially alkalized bamboo cellulose was dispersed in 14.29 kg of a 40 wt% sodium hydroxide solution. Since the bamboo cellulose content in the initially alkalized bamboo cellulose was close to the initial amount of bamboo cellulose, this application limits the amount of sodium hydroxide solution used for secondary alkalization to the initial amount of bamboo cellulose. After conversion, the weight ratio of bamboo cellulose to sodium hydroxide solution in the initially alkalized bamboo cellulose was approximately 7:100. The system was alkalized again at 20°C for 1.5 h to obtain 15.70 kg of alkali cellulose mixture.

[0055] Etherification: 0.80 kg of sodium chloroacetate was added to the alkali cellulose mixture, and the etherification reaction was carried out at a temperature of 60°C for 2 hours to obtain 16.50 kg of etherified cellulose mixture.

[0056] Crosslinking: Add 0.99 kg of epichlorohydrin to the etherified cellulose mixture, i.e., the weight ratio of crosslinking agent (0.99 kg) to etherified cellulose mixture (16.5 kg) is 6:100. The crosslinking reaction is carried out at 65℃ for 4 hours. After the etherified cellulose and crosslinking agent in the etherified cellulose mixture have completed crosslinking, wash with distilled water multiple times until no precipitation occurs in the waste liquid and a 0.1 mol / L silver nitrate solution (indicating complete removal of sodium chloride). Filter off the water with a sieve and dry in a drying oven until the moisture content is ≤10.0%, harvesting the bamboo-derived crosslinked carboxymethyl cellulose sodium (see [link to product description]). Figure 2 Its scanning electron microscope image is shown below. Figure 3 .

[0057] Example 2-3

[0058] Examples 2-3 are based on the preparation method of Example 1, but the concentration of sodium hydroxide solution in the initial alkalization is adjusted, as shown in Table 1.

[0059] Examples 4-5

[0060] Examples 4-5 are based on the preparation method of Example 1, but the concentration of sodium hydroxide solution in the second alkalization is adjusted, as shown in Table 1.

[0061] Example 6

[0062] This embodiment is based on the preparation method of Example 1, except that bamboo cellulose is replaced with commercially available powdered bamboo cellulose, and all other conditions remain unchanged. Bamboo-derived cross-linked carboxymethyl cellulose sodium is harvested (see Example 1). Figure 4 ).

[0063] Comparative Example 1

[0064] This comparative example is based on the preparation method of Example 1, except that "preliminary alkalization" is changed to "water soaking", that is, "2 wt% sodium hydroxide solution" is replaced with "distilled water".

[0065] Comparative Example 2

[0066] Based on the preparation method of Example 1, this comparative example changes "preliminary alkalization" to "alcohol soaking", that is, "2 wt% sodium hydroxide solution" is replaced with "85% ethanol solution".

[0067] Comparative Example 3

[0068] This comparative example is based on the preparation method of Example 1, but the concentration of sodium hydroxide solution in the "preliminary alkalization" is adjusted, as shown in Table 1.

[0069] Comparative Example 4

[0070] This comparative example is based on the preparation method of Example 1, but the concentration of sodium hydroxide solution in the "re-alkalization" is adjusted, as shown in Table 1.

[0071] Comparative Example 5

[0072] This comparative example is based on the preparation method of Example 1, except that bamboo cellulose is replaced with wood cellulose;

[0073] During the preparation process, the wood cellulose in this comparative example dissolved in the etherification step, and the resulting cross-linked sodium carboxymethyl cellulose (CCMC) obtained in the subsequent cross-linking step could not maintain its fibrous morphology and could only be presented in powder form. Therefore, the preparation process of this application is not suitable for preparing fibrous CCMC using conventional wood cellulose.

[0074] Comparative Example 6

[0075] This comparative example is based on the preparation method of Example 1, except that bamboo cellulose is replaced with cotton linters.

[0076] During the preparation process, the cotton linters in this comparative example also dissolved in the etherification step, and the cross-linked sodium carboxymethyl cellulose obtained in the subsequent cross-linking step could not maintain its fiber morphology and could only be presented in powder form. Therefore, the preparation process of this application is also unsuitable for preparing cross-linked sodium carboxymethyl cellulose in fiber form using conventional cotton linters.

[0077] Performance testing

[0078] The bamboo-derived crosslinked carboxymethyl cellulose sodium prepared in Examples 1-6 and Comparative Examples 1-6 were subjected to performance testing. First, the weight of the harvested bamboo-derived crosslinked carboxymethyl cellulose sodium was weighed using an electronic balance, which is the product yield. Then, the product identification, degree of substitution test, sodium chloride and sodium glycolate content test, and sedimentation volume test were carried out in accordance with the test methods for "crosslinked carboxymethyl cellulose sodium" in Part IV of the 2020 edition of the Chinese Pharmacopoeia.

[0079] It should be noted that the degree of substitution test can indirectly reflect the wetting effect of bamboo cellulose during the alkalization process. The higher the degree of substitution, the better the wetting effect, but the fiber strength will decrease accordingly. In order to ensure the comprehensive performance of bamboo-derived crosslinked sodium carboxymethyl cellulose, the pharmacopoeia stipulates that the standard-compliant degree of substitution range is 0.60-0.85.

[0080] The detection of sodium chloride and sodium glycolate content can effectively reflect the purity of bamboo-derived cross-linked carboxymethyl cellulose sodium. The lower the content of sodium chloride and sodium glycolate, the higher the purity of bamboo-derived cross-linked carboxymethyl cellulose sodium. The pharmacopoeia stipulates that the total amount of sodium chloride and sodium glycolate that meets the standard should be ≤0.5%.

[0081] The lower the degree of crosslinking of croscarmellose sodium, the greater its water solubility and the smaller its sedimentation volume; the higher the degree of crosslinking of croscarmellose sodium, the lower its water solubility and the larger its sedimentation volume. Sedimentation volume reflects the disintegration properties of croscarmellose sodium. Too much or too little sedimentation volume will result in the disintegration properties of croscarmellose sodium failing to meet the requirements. The pharmacopoeia stipulates that the standard sedimentation volume is 10.0-30.0 mL.

[0082] According to the above testing standards, the bamboo-derived crosslinked carboxymethyl cellulose sodium obtained in Examples 1-6 and Comparative Examples 1-6 of this application all meet the product identification standards. Other test results are shown in Table 1.

[0083] Table 1. Concentration and performance test results of sodium hydroxide solutions in Examples 1-6 and Comparative Examples 1-6

[0084]

[0085] Referring to Table 1, and combining the test results of Examples 1-6 and Comparative Examples 1-6, it can be seen that this application utilizes bamboo as a cellulose source, and with the operation of "preliminary alkalization + re-alkalization" and strict control of the sodium hydroxide solution concentration, it can harvest cross-linked carboxymethyl cellulose sodium with high yield, high purity (low total amount of sodium chloride and sodium glycolate), good wetting effect (relatively high degree of substitution), and sedimentation volume meeting the standard. In the preparation process, this application avoids the use of "alcohol" and eliminates the subsequent neutralization step, which not only reduces production costs and reduces the safety hazards of using and / or storing alcohol solvents, making the production process more green and environmentally friendly, but also effectively improves the production efficiency of bamboo-derived cross-linked carboxymethyl cellulose sodium.

[0086] Based on the test results of Examples 1 and 6, it can be seen that the preparation method of this application is applicable to bamboo cellulose in different states, that is, regardless of whether the bamboo cellulose is fibrous or powdered, the corresponding bamboo-derived cross-linked carboxymethyl cellulose sodium can be prepared. In addition, the yield, purity and degree of substitution of the fibrous bamboo cellulose prepared by this application are relatively higher. This is because the parameters in the preparation of bamboo cellulose are strictly controlled, which better promotes the alkalization of bamboo cellulose and obtains bamboo-derived cross-linked carboxymethyl cellulose sodium with a higher degree of substitution.

[0087] Examples 7-10

[0088] Based on the preparation method of Example 1, Examples 7-10 adjusted the weight ratio of bamboo cellulose to sodium hydroxide solution in the initial alkalization. The bamboo-derived crosslinked carboxymethyl cellulose sodium obtained by the adjustment scheme was subjected to the above performance test. The test results showed that the products all met the identification standards. Other test results and corresponding adjustments are shown in Table 2.

[0089] Table 2. Weight ratio and performance test results of bamboo cellulose to sodium hydroxide solution in Examples 1 and 7-10.

[0090]

[0091] As shown in Table 2, the croscarmellose sodium obtained under the above conditions meets the requirements of the pharmacopoeia. However, when the weight ratio of bamboo cellulose to sodium hydroxide solution is 1:0.5, the amount of sodium hydroxide solution is insufficient to completely submerge the bamboo cellulose, and the removal efficiency of lignin is not high, thus making it difficult to achieve a good wetting effect. The yield and degree of substitution of the harvested bamboo-derived croscarmellose sodium will be relatively low. When the weight ratio of bamboo cellulose to sodium hydroxide solution is 1:6, the yield and degree of substitution of the harvested bamboo-derived croscarmellose sodium are close to those when the weight ratio is 1:5. This indicates that adding too much low-concentration sodium hydroxide solution will result in some waste. Therefore, the weight ratio of bamboo cellulose to sodium hydroxide solution is further preferred to be 1:1-5.

[0092] Examples 11-14

[0093] Based on the preparation method of Example 1, Examples 11-14 adjusted the weight ratio of bamboo cellulose to sodium hydroxide solution in the initial alkalization of bamboo cellulose. The bamboo-derived crosslinked carboxymethyl cellulose sodium obtained by the adjustment scheme was subjected to the above performance test. The test results showed that the products all met the identification standards. Other test results and corresponding adjustments are shown in Table 3.

[0094] Table 3. Weight ratio and performance test results of initially alkalized bamboo cellulose to sodium hydroxide solution in Examples 1, 11-14.

[0095]

[0096] As shown in Table 3, the cross-linked carboxymethyl cellulose sodium obtained under the above conditions meets the requirements of the pharmacopoeia. However, when the weight ratio of bamboo cellulose to sodium hydroxide solution in the initial alkalization is 9:100, the yield and degree of substitution of the harvested bamboo-derived cross-linked carboxymethyl cellulose sodium are relatively low. This may be due to insufficient addition of sodium hydroxide solution, making it difficult to maintain a stable alkaline state in the system during subsequent etherification and cross-linking, thus causing some bamboo cellulose to degrade. When the weight ratio of bamboo cellulose to sodium hydroxide solution in the initial alkalization is 5:100, the purity and degree of substitution of the harvested bamboo-derived cross-linked carboxymethyl cellulose sodium are close to those when the weight ratio is 6:100, which indirectly indicates that excessive addition of sodium hydroxide solution will result in some waste. Therefore, a weight ratio of bamboo cellulose to sodium hydroxide solution in the initial alkalization of bamboo cellulose of 6-8:100 is further preferred.

[0097] Examples 15-19

[0098] Examples 15-19 are based on the preparation method of Example 1. The process parameters in the initial alkalization and re-alkalization are adjusted. The bamboo-derived crosslinked carboxymethyl cellulose sodium obtained by the adjustment scheme is subjected to the above performance test. In addition, the appearance is observed by visual comparison to see if it is yellowish. The test results show that the products all meet the identification standards. Other test results and corresponding adjustments are shown in Table 4.

[0099] Table 4. Alkalization process parameters and performance test results in Examples 1, 15-19

[0100]

[0101] As shown in Table 4, the yield, purity, degree of substitution, and appearance of bamboo-derived cross-linked carboxymethyl cellulose sodium (BLCMC) change with variations in alkalization temperature and time. Higher alkalization temperatures necessitate shorter alkalization times to ensure optimal yield and purity. Excessive temperature and / or time can lead to degradation, affecting both yield and appearance by causing the BLCMC to yellow. To better balance the concentrations of the two sodium hydroxide solutions, this application further optimizes alkalization at 15-35°C, with the alkalization time adjusted appropriately within the range of 0.5-3 hours.

[0102] Examples 20-22

[0103] Examples 20-22 are based on the preparation method of Example 1, with the addition amount of sodium chloroacetate adjusted. The bamboo-derived crosslinked carboxymethyl cellulose sodium prepared according to the adjusted scheme was subjected to the above performance test. The test results show that the products all meet the identification standards. Other test results and corresponding adjustments are shown in Table 5.

[0104] Table 5. Weight ratio and performance test results of bamboo cellulose to sodium chloroacetate in Examples 1, 20-22.

[0105] Example 1 Example 20 Example 21 Example 22 The weight ratio of bamboo cellulose to sodium chloroacetate 1:0.8 1:0.5 1:1 1:1.2 Yield / kg / kg bamboo cellulose 2.58 2.40 2.52 2.24 Substitutability 0.80 0.74 0.82 0.85 Total amount of sodium chloride and sodium glycolate / % 0.23 0.22 0.26 0.31 Sedimentation volume / mL 22.3 19.5 24.3 28.0

[0106] Based on the results in Table 5, the cross-linked carboxymethyl cellulose sodium obtained under the above conditions meets the requirements of the pharmacopoeia. However, excessive use of sodium chloroacetate can easily lead to over-substitution, causing cellulose to dissolve or form colloids, which in turn reduces the yield of bamboo-derived cross-linked carboxymethyl cellulose sodium. If the amount of sodium chloroacetate is too small, the degree of cellulose substitution will not meet the standard. Therefore, in the sodium hydroxide solution system of this application, the weight ratio of bamboo cellulose to sodium chloroacetate should be 1:0.5-1.

[0107] Examples 23-25

[0108] Examples 23-25 ​​are based on the preparation method of Example 1, with the amount of epichlorohydrin added adjusted. The bamboo-derived crosslinked carboxymethyl cellulose sodium prepared according to the adjusted scheme was subjected to the above performance test. The test results show that the products all meet the identification standards. Other test results and corresponding adjustments are shown in Table 6.

[0109] Table 6. Weight ratio and performance test results of crosslinking agent and etherified cellulose mixtures in Examples 1, 23-25.

[0110]

[0111] Based on the results in Table 6, the cross-linked carboxymethyl cellulose sodium obtained under the above conditions meets the requirements of the pharmacopoeia. However, if the amount of cross-linking agent is too low, the cross-linking of etherified cellulose will be incomplete, resulting in a lower yield of bamboo-derived cross-linked carboxymethyl cellulose sodium. On the other hand, excessive cross-linking agent will affect the purity of bamboo-derived cross-linked carboxymethyl cellulose sodium to a certain extent. Therefore, this application further optimizes the weight ratio of cross-linking agent to etherified cellulose mixture to be 1-10:100.

[0112] Examples 26-29

[0113] Examples 26-29 are based on the preparation method of Example 1, with adjustments made to the process parameters in etherification and crosslinking. The bamboo-derived crosslinked sodium carboxymethyl cellulose prepared according to the adjusted scheme was subjected to the above performance tests. The test results show that the products all meet the identification standards. Other test results and corresponding adjustments are shown in Table 7.

[0114] Table 7. Alkalization process parameters and performance test results in Examples 1, 26-29

[0115]

[0116] As shown in Table 7, the yield, purity, and degree of substitution of bamboo-derived crosslinked sodium carboxymethyl cellulose (BCC) all change with variations in the temperature and time corresponding to etherification and crosslinking. Higher etherification and crosslinking temperatures necessitate shorter reaction times to ensure higher yields, purity, and degree of substitution. Excessive temperature and / or prolonged reaction time can lead to degradation of the BCC, with the greatest impact on yield. To better balance the concentrations of the two sodium hydroxide solutions, this application further optimizes the reaction process by controlling the temperature at 50-70°C for 0.5-3 hours during etherification and by controlling the temperature at 60-70°C for 1-8 hours during crosslinking.

[0117] Examples 30-31

[0118] Examples 30-31 are based on the preparation method of Example 1, but the type of crosslinking agent is adjusted. The bamboo-derived crosslinked carboxymethyl cellulose sodium prepared according to the adjusted scheme is tested for the above-mentioned performance. The test results show that the products all meet the identification standards. Other test results and corresponding adjustments are shown in Table 8.

[0119] Table 8. Weight ratio and performance test results of crosslinking agent and etherified cellulose mixture in Examples 1, 30-31.

[0120]

[0121]

[0122] Based on the results in Table 8, it can be seen that the cross-linked carboxymethyl cellulose sodium obtained under the above conditions meets the requirements of the pharmacopoeia. However, this application utilizes the characteristics of epichlorohydrin, which has a fast cross-linking speed and high reactivity, to fully complete the cross-linking reaction with etherified cellulose, further ensuring the yield and purity of bamboo-derived cross-linked carboxymethyl cellulose sodium, with a smaller sedimentation volume and superior disintegration efficiency.

[0123] Application examples

[0124] The bamboo-derived crosslinked carboxymethyl cellulose sodium prepared in this application can be well applied in the fields of textiles, food, pharmaceuticals, electronic equipment, and industrial equipment. Compared with wood-derived crosslinked carboxymethyl cellulose sodium, the bamboo-derived crosslinked carboxymethyl cellulose sodium of this application has a stronger bonding strength between fibers and a porous structure, making it more widely applicable.

[0125] This application example specifically illustrates the use of bamboo-derived crosslinked carboxymethyl cellulose sodium prepared in Examples 1 and 5 in ciprofloxacin hydrochloride tablets, but is not limited thereto. The preparation method of the ciprofloxacin hydrochloride tablets is as follows:

[0126] The bamboo-derived cross-linked carboxymethyl cellulose sodium prepared in Example 1 was pulverized to 120 mesh. By weight, it was mixed and stirred in the following proportions: 71 parts ciprofloxacin hydrochloride, 4 parts microcrystalline cellulose, 3 parts povidone, 5 parts cross-linked carboxymethyl cellulose sodium, 1 part cross-linked povidone, 1 part colloidal silica, and 15 parts magnesium stearate. The mixture was then fed into a tablet press and compressed under a controlled pressure of 10 kN to produce ciprofloxacin hydrochloride tablets, which meet the requirements for "ciprofloxacin hydrochloride tablets" recorded in Part II of the 2020 edition of the Chinese Pharmacopoeia.

[0127] 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 preparation process for bamboo-derived cross-linked carboxymethyl cellulose sodium, characterized in that, Includes the following steps: Preliminary alkalization: Bamboo cellulose is dispersed in a sodium hydroxide solution with a concentration of 1-3 wt% for preliminary alkalization. After draining the sodium hydroxide solution, the preliminarily alkalized bamboo cellulose is obtained. Secondary alkalization: The initially alkalized bamboo cellulose is dispersed in a sodium hydroxide solution with a concentration of 30-45 wt% for secondary alkalization to obtain an alkali cellulose mixture; Etherification: Sodium chloroacetate is added to the alkali cellulose mixture to etherify it, thereby obtaining an etherified cellulose mixture; Crosslinking: A crosslinking agent is added to the etherified cellulose mixture. After the etherified cellulose in the etherified cellulose mixture and the crosslinking agent have completed crosslinking, the mixture is washed with water multiple times until no precipitation occurs in the waste liquid and silver nitrate solution, and bamboo-sourced crosslinked carboxymethyl cellulose sodium is harvested. In the preliminary alkalization step, the weight ratio of the bamboo cellulose to the sodium hydroxide solution is 1:1-5; In the re-alkalization step, the weight ratio of bamboo cellulose in the initially alkalized bamboo cellulose to the sodium hydroxide solution is 6-8:

100.

2. The preparation process of bamboo-derived crosslinked carboxymethyl cellulose sodium according to claim 1, characterized in that: The bamboo cellulose is initially alkalized at a temperature of 15-35℃ for 0.5-3 hours, and the initially alkalized bamboo cellulose is then alkalized again at a temperature of 15-35℃ for 0.5-3 hours.

3. The preparation process of bamboo-derived crosslinked carboxymethyl cellulose sodium according to claim 1, characterized in that: In the etherification step, the amount of sodium chloroacetate added is 0.5-1 times that of the bamboo cellulose.

4. The preparation process of bamboo-derived crosslinked carboxymethyl cellulose sodium according to claim 1, characterized in that: In the crosslinking step, the weight ratio of the crosslinking agent to the etherified cellulose mixture is 1-10:

100.

5. The preparation process of bamboo-derived crosslinked carboxymethyl cellulose sodium according to claim 1, characterized in that: In the etherification step, the reaction is controlled at 50-70℃ for 0.5-3 hours; in the crosslinking step, the reaction is controlled at 60-70℃ for 1-8 hours.

6. The preparation process of bamboo-derived crosslinked carboxymethyl cellulose sodium according to claim 1, characterized in that: In the crosslinking step, the crosslinking agent is epichlorohydrin.

7. A bamboo-derived cross-linked carboxymethyl cellulose sodium, characterized in that: It is prepared using the preparation process described in any one of claims 1-6.

8. The application of the bamboo-derived crosslinked carboxymethyl cellulose sodium according to claim 7 in the fields of textiles, food, pharmaceuticals, electronic equipment, and industrial equipment.

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