Process for the preparation of a modified sodium carboxymethyl cellulose

Abstract

The application discloses a preparation method of modified sodium carboxymethyl cellulose, and belongs to the technical field of preparation of sodium carboxymethyl cellulose. The specific dispersion liquid is added and is used in cooperation with ultrasonic waves, can effectively penetrate the dense crystallization area of fibers, destroy the hydrogen bond network of the fibers, and make the fibers in a loose state, so that more reaction sites are exposed for subsequent alkalization and etherification reactions. In addition, by spraying a functional additive on the surface of the sodium carboxymethyl cellulose, the obtained modified sodium carboxymethyl cellulose can not only retain most of the properties of the sodium carboxymethyl cellulose, but also can cooperate with modified silicon dioxide, so as to endow the modified sodium carboxymethyl cellulose with excellent antibacterial properties and thermal stability, and further has a wider application field. Moreover, the overall preparation process is simple, operability is high, and is suitable for factory scale production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sodium carboxymethyl cellulose preparation, in particular to a preparation method of modified sodium carboxymethyl cellulose. BACKGROUND

[0002] Sodium carboxymethyl cellulose is an anion, straight chain, water-soluble cellulose ether, which is a derivative obtained by chemical modification of natural cellulose and chloroacetic acid. The aqueous solution has the effects of thickening, film forming, bonding, water retention, colloid protection, emulsification, suspension, etc., and can be used as a flocculating agent, a chelating agent, an emulsifying agent, a thickening agent, a water-retaining agent, a film-forming material, etc., and is widely used in food, medicine, electronics, pesticides, leather, plastics, printing and other fields.

[0003] The sodium carboxymethyl cellulose in the prior art is generally prepared by water medium method, low multiple solvent method, slurry method (also known as multiple solvent method) and the like; but the water medium method uses water as the reaction medium, and the water content of the reaction system is too much, resulting in low etherification efficiency; the low multiple solvent method has poor sealing performance; the sodium carboxymethyl cellulose prepared by the slurry method has poor salt resistance and acid resistance, and in an acidic environment or a high-salt environment, the electrostatic repulsion between the molecular chains of the sodium carboxymethyl cellulose is weakened, resulting in the curling of the molecular chains, the significant decrease of the solution viscosity and even the precipitation, so that the performance of the sodium carboxymethyl cellulose in the application in acidic food, beverage or high-mineralization oil field fracturing fluid and the like is affected. Secondly, degradation is prone to occur during the preparation, resulting in viscosity loss, and the stability of the sodium carboxymethyl cellulose prepared by the traditional method, especially the thermal stability, still needs to be improved. In addition, the function is single, and the application performance cannot meet the use requirements. For example, the patent application No. CN202410047437.4 provides a preparation method of sodium carboxymethyl cellulose. A preparation method of sodium carboxymethyl cellulose, characterized in that: comprising the following steps: pretreatment: the plant fiber is subjected to loosening and crushing treatment, then is passed through an 80-100 mesh sieve to prepare cellulose powder; alkalization: the cellulose powder is dispersed in a primary alkali solution to perform alkalization, to prepare alkali cellulose; primary etherification; secondary etherification; neutralization, to prepare crude sodium carboxymethyl cellulose; after filtration, washing, drying and crushing, the refined sodium carboxymethyl cellulose is dispersed in a permeate solution, is subjected to soaking treatment, then is centrifuged, and the centrifuged substance is subjected to instantaneous pressure difference puffing treatment, then is crushed to prepare instant sodium carboxymethyl cellulose. The scheme has the advantages of guaranteeing the viscosity of the sodium carboxymethyl cellulose and improving the dissolution rate of the sodium carboxymethyl cellulose. For example, the patent application No. CN202311194585.0 discloses a modified sodium carboxymethyl cellulose and a preparation method and application thereof. The modified sodium carboxymethyl cellulose obtained by the scheme has good solubility in slurry, excellent dispersion and suspension capacity for active materials and conductive agents, has potential capacity to improve the coating speed and to improve the production efficiency of the pole piece. However, the prior art cannot balance the salt resistance and temperature resistance of the modified sodium carboxymethyl cellulose while improving the application of the modified sodium carboxymethyl cellulose in the antibacterial field, and the modification effect is not ideal. SUMMARY

[0004] Therefore, in order to overcome one of the above problems, the present application provides a preparation method of modified sodium carboxymethyl cellulose, and the specific technical scheme is as follows:

[0005] A preparation method of modified sodium carboxymethyl cellulose, comprising the following steps:

[0006] S1. soaking the fiber in dilute alkali, then washing, airing and drying to obtain material A;

[0007] S2. Add the material A to the dispersion liquid and perform ultrasonic treatment, then add the lye A to perform the first alkalization, and after washing to neutral, continue to add the lye B to perform the second alkalization, and after washing to neutral, obtain the material B;

[0008] S3. Perform etherification treatment on the material B, and after neutralization, washing and drying treatment, obtain the sodium carboxymethyl cellulose;

[0009] S4. Sprinkle the functional additives uniformly on the surface of the sodium carboxymethyl cellulose, dry and crush to obtain the modified sodium carboxymethyl carboxymethyl cellulose.

[0010] Preferably, in step S1, the dilute alkali soaking treatment is: adding the fiber to a NaOH aqueous solution with a mass percentage concentration of 0.6-0.8%, stirring at a speed of 50-100 r / min at room temperature for 3-5 h;

[0011] The solid-liquid ratio of the fiber to the NaOH aqueous solution is (1-3) g / 20 mL.

[0012] Preferably, in step S2, the dispersion liquid comprises the following ingredients by weight: base solvent 40-50 parts, modified silica 1-3 parts, sodium silicate 1-5 parts, and dispersant 0.1-1 part.

[0013] Preferably, the base solvent is obtained by mixing ethanol and water in a volume ratio of 1:1;

[0014] The modified silica is γ-aminopropyl triethoxysilane modified silica, and the particle size of the modified silica is 10-30 nm;

[0015] The dispersant is polyacrylamide.

[0016] Preferably, in step S2, the ultrasonic treatment is performed at a power of 100-200 W, a frequency of 25-40 kHz, and a time of 15-30 min.

[0017] Preferably, in step S2, the lye A is a NaOH aqueous solution with a mass percentage concentration of 15-20%;

[0018] The temperature of the first alkalization is 30-40℃, and the time is 30-60 min;

[0019] The lye B is a NaOH aqueous solution with a mass percentage concentration of 8-12%;

[0020] The temperature of the second alkalization is 25-40℃, and the time is 50-60 min.

[0021] Preferably, in step S3, the etherifying agent for the etherification treatment is an ethanol aqueous solution of sodium chloroacetate.

[0022] The weight ratio of the material B to the etherifying agent is (10-15):(4-7).

[0023] In the ethanol aqueous solution of sodium chloroacetate, the volume fraction of sodium chloroacetate is 15-20%.

[0024] Preferably, in step S3, the etherification treatment is: first, treatment at 30-40℃ for 30-40min, then treatment at a temperature of 50-60℃ for 30-60min, and finally, treatment at a temperature of 70-80℃ for 20-30min.

[0025] Preferably, in step S4, the preparation method of the functional additive is: adding chitosan into an aqueous solution of ethylene glycol diglycidyl ether, then adding dodecyl dimethyl benzyl ammonium bromide and sodium tetraborate, and treating at a rotation speed of 100r / min-200r / min and a temperature of 45-65℃ for 1-5h.

[0026] In addition, the present application also provides a modified sodium carboxymethyl cellulose, which is prepared by the preparation method of the present application.

[0027] Compared with the prior art, the present application has the following beneficial effects:

[0028] 1. The present application adds a specific dispersion liquid for treatment, which can effectively penetrate the dense crystalline region of the fiber, destroy the hydrogen bond network of the fiber, and make it in a loose state, thereby exposing more reaction sites for subsequent alkalization and etherification reaction. Among them, the surface amino group of modified silicon dioxide and the fiber have hydrogen bond effect, which enhances its adsorption on the surface of the fiber. Under the action of ultrasonic, it can be embedded into the gap of the fiber bundle like a "micro wedge", and can strongly separate the fibers by using the steric hindrance effect, and prevent the fibers from agglomerating again. In addition, it also introduces functional groups for subsequent modification, so as to form a synergistic effect with the functional additive. Sodium silicate can help to reduce the excessive degradation of the fiber, and polyacrylamide can be adsorbed on the surface of the separated fiber by van der Waals force or hydrogen bond, and can prevent the fibers from approaching and agglomerating by a certain steric hindrance effect, and can form a "bridge" between different fibers, which is helpful to build a more loose three-dimensional network structure.

[0029] 2. The present application cooperates the dispersion liquid with the ultrasonic effect, and the shear force and impact generated by the cavitation effect of ultrasonic can further promote the penetration of the dispersion liquid components into the fiber, and then effectively play the "micro wedge" effect of modified silicon dioxide, and promote to obtain a product with more stable salt and temperature resistance.

[0030] 3. The present application can retain the original performance of sodium carboxymethyl cellulose by spraying a functional aid on the surface of sodium carboxymethyl cellulose, and can also increase the temperature resistance of modified sodium carboxymethyl cellulose and impart excellent antibacterial properties to it, so that it has a wider application field.

[0031] 4. The overall preparation process of the modified sodium carboxymethyl cellulose of the present application is simple and easy to operate, and is suitable for factory scale production. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below in combination with its embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the protection scope of the present application.

[0033] It should be noted that the sources of the components not specifically described in the present application can be purchased from the market, and the processes not specifically described can be understood as conventional technical means.

[0034] The preparation method of the modified sodium carboxymethyl cellulose in an embodiment of the present application comprises the following steps:

[0035] S1. The fiber is subjected to dilute alkali soaking treatment, then washed, dried, and material A is obtained;

[0036] S2. The material A is added to a dispersion liquid and subjected to ultrasonic treatment, then an alkali solution A is added for the first alkalization, and then washed to neutral, an alkali solution B is continuously added for the second alkalization, and then washed to neutral, and material B is obtained;

[0037] S3. The material B is subjected to etherification treatment, and then subjected to neutralization, washing and drying treatment, and sodium carboxymethyl cellulose is obtained;

[0038] S4. The functional aid is uniformly sprayed on the surface of the sodium carboxymethyl cellulose, dried and crushed, and modified sodium carboxymethyl cellulose is obtained.

[0039] In one of the embodiments, in step S1, the dilute alkali soaking treatment is: the fiber is added to a NaOH aqueous solution with a mass percentage concentration of 0.6-0.8%, and stirred at a speed of 50-100 r / min at room temperature for 3-5 h;

[0040] The solid-liquid ratio of the fiber to the NaOH aqueous solution is (1-3) g / 20 mL. The present application selects a relatively mild condition for dilute alkali soaking treatment, which can effectively avoid the premature and excessive degradation of cellulose, and also can increase the content of a-cellulose, and the content of a-cellulose is ≥95%.

[0041] In one embodiment, in step S1, the fiber is at least one of bamboo fiber and wood fiber.

[0042] In one embodiment, in step S1, deionized water is used for washing.

[0043] In one embodiment, in step S1, the weight ratio of the fiber to the dilute alkali is (5-10):(10-20).

[0044] In one embodiment, in step S2, the dispersion comprises the following components in parts by weight: 40-50 parts of base solvent, 1-3 parts of modified silica, 1-5 parts of sodium silicate, and 0.1-1 parts of dispersant.

[0045] In one embodiment, the base solvent is obtained by mixing ethanol and water in a volume ratio of 1:1;

[0046] The modified silica is γ-aminopropyltriethoxysilane modified silica, and the particle size of the modified silica is 10nm-30nm.

[0047] The dispersant is polyacrylamide.

[0048] In one embodiment, the weight ratio of material A, dispersion, alkali solution A and alkali solution B is (5-10):(10-20):(15-30):(20-50).

[0049] In one embodiment, in step S2, the conditions for the ultrasonic action are: power of 100-200W, frequency of 25-40kHz, and duration of 15-30min.

[0050] In one embodiment, in step S2, the alkaline solution A is a NaOH aqueous solution with a mass percentage concentration of 15-20%;

[0051] The temperature for the first alkalization is 30-40℃, and the time is 30-60 minutes.

[0052] The alkaline solution B is an aqueous solution of NaOH with a mass percentage concentration of 8-12%.

[0053] The second alkalization is performed at a temperature of 25-40℃ for 50-60 minutes.

[0054] In one embodiment, in step S2, deionized water is used for washing.

[0055] This invention employs a two-stage alkalization process, which can more fully and uniformly activate the groups on the fiber molecular chain, creating more favorable conditions for the subsequent etherification reaction and helping to improve the degree of substitution and reaction efficiency.

[0056] In one embodiment, in step S3, the etherifying agent for the etherification treatment is an aqueous solution of sodium chloroacetate in ethanol;

[0057] The weight ratio of material B to the etherifying agent is (10-15):(4-7).

[0058] The volume fraction of sodium chloroacetate in the ethanol aqueous solution is 15-20%.

[0059] In one embodiment, in step S3, the etherification process is as follows: first, the treatment is carried out at 30-40°C for 30-40 minutes, then at 50-60°C for 30-60 minutes, and then at 70-80°C for 20-30 minutes.

[0060] In one embodiment, in step S3, after etherification, the pH of the reaction system is adjusted to 6.5-7.5 with an 85-90% (v / v) glacial acetic acid solution, filtered, and then washed multiple times with 75-80% (v / v) ethanol, followed by one wash with 90-95% (v / v) ethanol. Finally, it is dried at 65-70°C for 5-8 hours. This invention uses a glacial acetic acid reaction system. Although glacial acetic acid is a weak acid, its relatively mild nature is conducive to the stable progress of the ion exchange reaction. Simultaneously, the buffering capacity of glacial acetic acid effectively stabilizes the pH value of the reaction system, preventing excessive pH fluctuations from affecting product quality.

[0061] In one embodiment, in step S4, the preparation method of the functional additive is as follows: chitosan is added to an aqueous solution of ethylene glycol diglycidyl ether, and then dodecyl dimethyl benzyl ammonium bromide and sodium tetraborate are added, and the mixture is treated for 1-5 hours at a rotation speed of 100 r / min-200 r / min and a temperature of 45-65°C.

[0062] In one embodiment, the volume fraction of ethylene glycol diglycidyl ether in the aqueous solution is 8-15%.

[0063] In one embodiment, the weight ratio of the chitosan, the aqueous solution of ethylene glycol diglycidyl ether, dodecyl dimethyl benzyl ammonium bromide and sodium tetraborate is (7~15):(20-50):(1-5):(1-2).

[0064] In one embodiment, the functional additive is in a weight ratio of (1-5):10 with sodium carboxymethyl cellulose.

[0065] In one embodiment, in step S4, the drying temperature is 75-120°C and the time is 1-3 hours.

[0066] In one embodiment, the present invention also provides a modified sodium carboxymethyl cellulose, which is prepared by the preparation method described in the present invention.

[0067] In one embodiment, the modified sodium carboxymethyl cellulose has a core-shell structure, with the core being the sodium carboxymethyl cellulose backbone and the shell being a functional additive graft chain.

[0068] The modified sodium carboxymethyl cellulose obtained by the above scheme can not only meet the special requirements of different application scenarios for flowability and thickening performance, but also exhibit excellent network structure stability and significant antibacterial properties.

[0069] The implementation schemes of the present invention will now be described in detail with reference to specific embodiments. Example 1:

[0070] A method for preparing modified sodium carboxymethyl cellulose includes the following steps:

[0071] S1. By weight, 10 parts of bamboo fiber were added to 20 parts of NaOH aqueous solution with a mass percentage concentration of 0.8%. The mixture was stirred at 80 r / min for 3 hours at room temperature. After washing with deionized water and drying, material A was obtained.

[0072] S2. According to the weight ratio, 10 parts of the material A are added to 18 parts of the dispersion, and ultrasonically treated for 20 minutes at a power of 100W and a frequency of 30kHz. Then, 20 parts of a 16% NaOH aqueous solution are added, and the first alkalization is carried out at a temperature of 30℃ for 60 minutes. After washing with deionized water until neutral, 35 parts of a 12% NaOH aqueous solution are added, and the second alkalization is carried out at a temperature of 30℃ for 60 minutes. After washing with deionized water until neutral, material B is obtained.

[0073] The dispersion comprises the following components in parts by weight: 50 parts of base solvent (obtained by mixing ethanol and water in a volume ratio of 1:1), 3 parts of γ-aminopropyltriethoxysilane modified silica (particle size of 25 nm), 3 parts of sodium silicate, and 0.5 parts of polyacrylamide.

[0074] S3. According to the weight ratio, 10 parts of the material B are added to the etherification treatment device, and then 7 parts of etherifying agent (sodium chloroacetate in an ethanol aqueous solution, with a volume fraction of 20% sodium chloroacetate) are added successively to carry out etherification treatment. The etherification treatment process is as follows: first, the treatment is carried out at 40°C for 35 min, then at 55°C for 45 min, and then at 80°C for 20 min. After etherification treatment, the pH of the reaction system is adjusted to 7.1 with 90% glacial acetic acid solution, filtered, and then washed multiple times with 80% ethanol, then washed once with 95% ethanol, and finally dried at 70°C for 7 h to obtain sodium carboxymethyl cellulose.

[0075] S4. Spray 4 parts of functional additives evenly onto the surface of 10 parts of the sodium carboxymethyl cellulose, dry at 100°C for 2 hours, pulverize, and obtain modified sodium carboxymethyl cellulose.

[0076] In this process, 10 parts by weight of chitosan were added to an aqueous solution of 23 parts of ethylene glycol diglycidyl ether, followed by the addition of 4 parts of dodecyl dimethyl benzyl ammonium bromide and 1 part of sodium tetraborate. The mixture was then treated for 3 hours at a rotation speed of 100 r / min and a temperature of 60 °C to obtain the functional additive. Example 2:

[0077] A method for preparing modified sodium carboxymethyl cellulose includes the following steps:

[0078] S1. By weight, 10 parts of bamboo fiber were added to 15 parts of NaOH aqueous solution with a mass percentage concentration of 0.6%. The mixture was stirred at 50 r / min for 4 hours at room temperature. After washing with deionized water and drying, material A was obtained.

[0079] S2. According to the weight ratio, 10 parts of the material A are added to 18 parts of the dispersion, and ultrasonically treated for 25 minutes at a power of 120W and a frequency of 28kHz. Then, 20 parts of a 17% NaOH aqueous solution are added, and the first alkalization is carried out at a temperature of 35℃ for 50 minutes. After washing with deionized water until neutral, 30 parts of a 12% NaOH aqueous solution are added, and the second alkalization is carried out at a temperature of 40℃ for 50 minutes. After washing with deionized water until neutral, material B is obtained.

[0080] The dispersion comprises the following components by weight: 50 parts of base solvent (obtained by mixing ethanol and water in a volume ratio of 1:1), 3 parts of γ-aminopropyltriethoxysilane modified silica (particle size of 25 nm), 2 parts of sodium silicate, and 0.6 parts of polyacrylamide.

[0081] S3. According to the weight ratio, 10 parts of the material B are added to the etherification treatment device, and then 5 parts of etherifying agent (sodium chloroacetate in an ethanol aqueous solution, with a volume fraction of 20% sodium chloroacetate) are added successively to carry out etherification treatment. The etherification treatment process is as follows: first, the treatment is carried out at 40°C for 40 min, then at 55°C for 60 min, and then at 80°C for 25 min. After etherification treatment, the pH of the reaction system is adjusted to 7.0 with 90% glacial acetic acid solution, filtered, and then washed multiple times with 80% ethanol, then washed once with 95% ethanol, and finally dried at 70°C for 6 h to obtain sodium carboxymethyl cellulose.

[0082] S4. Spray 5 parts of functional additives evenly onto the surface of 10 parts of the sodium carboxymethyl cellulose, dry at 100℃ for 2 hours, pulverize, and obtain modified sodium carboxymethyl cellulose.

[0083] In this process, 12 parts by weight of chitosan were added to an aqueous solution of 30 parts of ethylene glycol diglycidyl ether, followed by the addition of 4 parts of dodecyl dimethyl benzyl ammonium bromide and 2 parts of sodium tetraborate. The mixture was then treated for 3 hours at a rotation speed of 100 r / min and a temperature of 65 °C to obtain the functional additive. Example 3:

[0084] A method for preparing modified sodium carboxymethyl cellulose, the method comprising the following steps:

[0085] S1. By weight, 10 parts of bamboo fiber were added to 20 parts of NaOH aqueous solution with a mass percentage concentration of 0.6%. The mixture was stirred at 50 r / min for 3 hours at room temperature. After washing with deionized water and drying, material A was obtained.

[0086] S2. According to the weight ratio, 10 parts of the material A are added to 15 parts of the dispersion, and ultrasonically treated for 20 minutes at a power of 150W and a frequency of 30kHz. Then, 25 parts of a 16% NaOH aqueous solution are added, and the first alkalization is carried out at a temperature of 35℃ for 45 minutes. After washing with deionized water until neutral, 40 parts of a 12% NaOH aqueous solution are added, and the second alkalization is carried out at a temperature of 30℃ for 60 minutes. After washing with deionized water until neutral, material B is obtained.

[0087] The dispersion comprises the following components in parts by weight: 50 parts of base solvent (obtained by mixing ethanol and water in a volume ratio of 1:1), 2 parts of γ-aminopropyltriethoxysilane modified silica (particle size of 25 nm), 3 parts of sodium silicate, and 0.5 parts of polyacrylamide.

[0088] S3. According to the weight ratio, 10 parts of the material B are added to the etherification treatment device, and then 6 parts of etherifying agent (sodium chloroacetate in an ethanol aqueous solution, with a volume fraction of 20% sodium chloroacetate) are added successively to carry out etherification treatment. The etherification treatment process is as follows: first, the treatment is carried out at 35°C for 35 min, then at 60°C for 45 min, and then at 80°C for 25 min. After etherification treatment, the pH of the reaction system is adjusted to 7.0 with 90% glacial acetic acid solution, filtered, and then washed multiple times with 80% ethanol, then washed once with 95% ethanol, and finally dried at 70°C for 8 h to obtain sodium carboxymethyl cellulose.

[0089] S4. Spray 5 parts of functional additives evenly onto the surface of 10 parts of the sodium carboxymethyl cellulose, dry at 95°C for 3 hours, pulverize, and obtain modified sodium carboxymethyl cellulose.

[0090] In this process, 10 parts by weight of chitosan were added to an aqueous solution of 25 parts of ethylene glycol diglycidyl ether, followed by the addition of 3 parts of dodecyl dimethyl benzyl ammonium bromide and 2 parts of sodium tetraborate. The mixture was then treated for 2 hours at a rotation speed of 100 r / min and a temperature of 60 °C to obtain the functional additive.

[0091] Comparative Example 1:

[0092] The difference between Comparative Example 1 and Example 3 is that Comparative Example 1 did not undergo the dilute alkali soaking treatment in step S1, but was otherwise the same as Example 3.

[0093] Comparative Example 2:

[0094] The difference between Comparative Example 2 and Example 3 is that the dispersion in Comparative Example 2 did not contain γ-aminopropyltriethoxysilane-modified silica, while the rest was the same as in Example 3.

[0095] Comparative Example 3:

[0096] The difference between Comparative Example 3 and Example 3 is that sodium silicate was not added to the dispersion of Comparative Example 3, but otherwise the same as Example 3.

[0097] Comparative Example 4:

[0098] The difference between Comparative Example 4 and Example 3 is that no polyacrylamide was added to the dispersion of Comparative Example 4, but otherwise it was the same as Example 3.

[0099] Comparative Example 5:

[0100] The difference between Comparative Example 5 and Example 3 is that Comparative Example 5 was not pre-treated in the dispersion, but directly entered the first alkalization treatment. Otherwise, it was the same as Example 3.

[0101] Comparative Example 6:

[0102] The difference between Comparative Example 6 and Example 3 is that Comparative Example 6 was not subjected to ultrasonic treatment, but otherwise it was the same as Example 3.

[0103] Comparative Example 7:

[0104] The difference between Comparative Example 7 and Example 3 is that the preparation method of the functional additive in Comparative Example 7 is different, while the rest is the same as in Example 3;

[0105] The preparation method of the functional additive in Comparative Example 7 is as follows: 10 parts by weight of chitosan were added to 25 parts by weight of water, and then 3 parts by weight of dodecyl dimethyl benzyl ammonium bromide were added. The mixture was treated for 2 hours at a speed of 100 r / min and a temperature of 60 °C to obtain the functional additive.

[0106] Comparative Example 8:

[0107] The difference between Comparative Example 8 and Example 3 is that the preparation method of the functional additive in Comparative Example 8 is different, while the rest is the same as in Example 3.

[0108] The preparation method of the functional additive in Comparative Example 8 is as follows: 10 parts by weight of chitosan were added to an aqueous solution of 25 parts of ethylene glycol diglycidyl ether, and then 2 parts of sodium tetraborate were added. The mixture was treated for 2 hours at a speed of 100 r / min and a temperature of 60℃ to obtain the functional additive.

[0109] Comparative Example 9:

[0110] The difference between Comparative Example 9 and Example 3 is that the preparation method of the functional additive in Comparative Example 9 is different, while the rest is the same as in Example 3;

[0111] The preparation method of the functional additive in Comparative Example 9 is as follows: 10 parts by weight of chitosan were added to 25 parts by weight of an aqueous solution of ethylene glycol diglycidyl ether, and then 3 parts by weight of dodecyl dimethyl benzyl ammonium bromide were added. The mixture was treated for 2 hours at a speed of 100 r / min and a temperature of 60 °C to obtain the functional additive.

[0112] Comparative Example 10:

[0113] The difference between Comparative Example 10 and Example 3 is that no functional additives were added in Comparative Example 10, but otherwise it is the same as Example 3.

[0114] The modified sodium carboxymethyl cellulose samples obtained in Examples 1-3 and the comparative samples of modified sodium carboxymethyl cellulose obtained in Comparative Examples 1-10 were subjected to performance tests.

[0115] I. Salt Tolerance Test

[0116] Test method: The modified sodium carboxymethyl cellulose samples of Examples 1-3 and the comparative samples of modified sodium carboxymethyl cellulose prepared in Comparative Examples 1-10 were added to pure water (A), 1% NaCl solution (B), and 2% NaCl solution (C), respectively, to prepare a solution with a volume fraction of 0.5 wt% modified sodium carboxymethyl cellulose. After swelling and stabilization, the viscosity was measured using a rheometer at a shear rate of 170 r / s and a temperature of 25 °C. The salt resistance was tested, and the results are shown in Table 1 below.

[0117] Table 1: Salt tolerance test results (mPa.s)

[0118] Group Pure water (A) 1% NaCl (B) 2% NaCl (C) Example 1 3217 2879 2643 Example 2 3145 2756 2558 Example 3 3156 2748 2561 Comparative Example 1 2842 2667 2450 Comparative Example 2 2611 1922 1626 Comparative Example 3 2712 2005 1712 Comparative Example 4 2654 1958 1659 Comparative Example 5 2424 1762 1445 Comparative Example 6 2551 1853 1551 Comparative Example 7 2910 2215 1913 Comparative Example 8 2856 2129 1827 Comparative Example 9 2812 2057 1755 Comparative Example 10 2621 1855 1556

[0119] Analysis of the data in Table 1 shows that the modified sodium carboxymethyl cellulose prepared by this invention has higher viscosity, excellent overall salt resistance, and is relatively stable.

[0120] Comparative Example 1, without dilute alkali treatment, showed a slight decrease in viscosity, indicating that dilute alkali soaking can initially disrupt the dense crystalline structure of cellulose and promote fiber activation. Comparative Examples 2-4 all had different dispersion compositions, but their viscosity decreased to varying degrees, indicating a significant synergistic effect among the components in the dispersion. Comparative Example 5, without dispersion treatment, showed poor viscosity of the modified carboxymethyl cellulose sodium, indicating that the dispersion can effectively promote a product with a higher degree of substitution, making it more suitable for application requirements. Comparative Example 6, without ultrasonic treatment, showed poor viscosity, indicating that the dispersion and ultrasonic treatment can effectively disperse the fibers, exposing more reaction sites. Comparative Examples 7-9 had different functional additive compositions, while Comparative Example 10, without added functional additives, showed decreased salt resistance, indicating that complete functional additive components have a positive impact on the construction of the core-shell structure and stability, and that functional additive components can significantly improve the salt resistance of modified carboxymethyl cellulose sodium.

[0121] II. Temperature Resistance Test

[0122] Test method: The modified sodium carboxymethyl cellulose samples of Examples 1-3 and the comparative samples of modified sodium carboxymethyl cellulose prepared in Comparative Examples 1-10 were added to pure water to prepare a solution with a mass fraction of 0.5 wt% modified sodium carboxymethyl cellulose. After swelling and stabilization, the viscosity was measured using a rheometer at a shear rate of 170 r / s, a temperature of 150 ℃, and a shearing time of 60 min. The results are shown in Table 2.

[0123] Table 2: Temperature resistance test results (mPa.s)

[0124] Group Pure water (150°C) (A) Example 1 2512 Example 2 2459 Example 3 2462 Comparative Example 1 2325 Comparative Example 2 1758 Comparative Example 3 1752 Comparative Example 4 1655 Comparative Example 5 1512 Comparative Example 6 1685 Comparative Example 7 1925 Comparative Example 8 1856 Comparative Example 9 1848 Comparative Example 10 1611

[0125] As can be seen from Table 2, the modified sodium carboxymethyl cellulose prepared in this invention still maintains a high viscosity at a temperature of 150°C, indicating that it has excellent thermal properties.

[0126] Comparative Example 1, without dilute alkali soaking, exhibited high fiber density, which affected the effective penetration of the subsequent dispersion, resulting in a slight decrease in viscosity. This indicates that dilute alkali soaking has a certain promoting effect on the temperature resistance of the fiber. Comparative Examples 2-5 all featured different dispersion compositions, yet the viscosity decreased to varying degrees. This suggests that the components in the dispersion worked synergistically to promote modification, cross-linking, and / or grafting, contributing to improved temperature resistance of the modified sodium carboxymethyl cellulose. In particular, Comparative Example 5, lacking a dispersion, resulted in fewer internal reaction sites, cellulose chain breakage, and increased structural defects, affecting heat stability. Comparative Example 6, without ultrasonic treatment, still showed an impact on temperature resistance, indicating that the cavitation effect of ultrasonic treatment, synergistically with the dispersion, significantly influenced fiber crystallization. Comparative Examples 7-9 featured different functional additive compositions, while Comparative Example 10, without added functional additives, exhibited weakened cross-linking, all of which negatively impacted the thermal stability of the modified sodium carboxymethyl cellulose.

[0127] III. Antibacterial Test

[0128] Test method: The filter paper method was used for testing: The modified sodium carboxymethyl cellulose samples obtained in Examples 1-3 and the comparative samples of modified sodium carboxymethyl cellulose obtained in Comparative Examples 1-10 were placed in petri dishes containing bacteria (Staphylococcus aureus) and incubated at 25°C in a constant temperature incubator. After 7 days, the growth was observed and the size of the inhibition zone was measured (the bacteria grow to form multiple colonies, and each colony is surrounded by a transparent zone where no colonies grow, which is the inhibition zone).

[0129] The inhibition effect was recorded as follows: Level 5: inhibition zone diameter greater than 20 mm, showing significant antibacterial effect; Level 4: inhibition zone diameter 16-20 mm, showing strong antibacterial effect; Level 3: inhibition zone diameter 13-16 mm, showing antibacterial effect; Level 2: inhibition zone diameter 10-3 mm, showing no significant antibacterial effect; Level 1: inhibition zone diameter 7-10 mm, showing weak antibacterial effect; Level 0: 7 mm (filter paper diameter), blank control. The inhibition zone diameter was measured twice using a cross-sectional method, and the average value was taken. The results are shown in Table 3 below.

[0130] Table 3: Antibacterial Properties (Grade)

[0131] Group Antibacterial property (grade) Example 1 5 Example 2 5 Example 3 5 Comparative Example 1 4 Comparative Example 2 3 Comparative Example 3 4 Comparative Example 4 3 Comparative Example 5 2 Comparative Example 6 3 Comparative Example 7 3 Comparative Example 8 2 Comparative Example 9 4 Comparative Example 10 1

[0132] The data analysis in Table 3 shows that the comparative analysis of antibacterial data in Comparative Examples 1-10 also clearly demonstrates that the synergistic effect of the components and the process can promote the acquisition of products with better cross-linking properties and has a significant promoting effect on antibacterial performance. The modified sodium carboxymethyl cellulose obtained by this invention has significant antibacterial properties.

[0133] 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 modified sodium carboxymethyl cellulose, characterized in that, The preparation method includes the following steps: S1. The fiber is soaked in dilute alkali, then washed and dried to obtain material A; S2. Add the material A to the dispersion and sonicate it. Then add alkaline solution A for the first alkalization. Wash until neutral. Add alkaline solution B for the second alkalization. Wash until neutral to obtain material B. The dispersion comprises the following components by weight: 40-50 parts of base solvent, 1-3 parts of modified silica, 1-5 parts of sodium silicate, and 0.1-1 parts of dispersant; wherein the base solvent is obtained by mixing ethanol and water in a volume ratio of 1:1; the modified silica is γ-aminopropyltriethoxysilane-modified silica, and the particle size of the modified silica is 10nm-30nm; the dispersant is polyacrylamide. S3. Etherify the material B, then neutralize, wash and dry it to obtain sodium carboxymethyl cellulose; S4. The functional additive is evenly sprayed onto the surface of the sodium carboxymethyl cellulose, dried and pulverized to obtain modified sodium carboxymethyl cellulose; The preparation method of the functional additive is as follows: chitosan is added to an aqueous solution of ethylene glycol diglycidyl ether, and then dodecyl dimethyl benzyl ammonium bromide and sodium tetraborate are added. The mixture is then treated for 1-5 hours at a rotation speed of 100-200 r / min and a temperature of 45-65℃.

2. The preparation method according to claim 1, characterized in that, In step S1, the dilute alkali soaking treatment is as follows: the fiber is added to a NaOH aqueous solution with a mass percentage concentration of 0.6-0.8%, and stirred at 50-100 r / min for 3-5 hours at room temperature; The ratio of the fiber to the NaOH aqueous solution is (1-3) g / 20 mL.

3. The preparation method according to claim 1, characterized in that, In step S2, the conditions for the ultrasonic action are: power of 100-200W, frequency of 25-40kHz, and time of 15-30min.

4. The preparation method according to claim 1, characterized in that, In step S2, the alkaline solution A is a NaOH aqueous solution with a mass percentage concentration of 15-20%; The temperature for the first alkalization is 30-40℃, and the time is 30-60 minutes. The alkaline solution B is an aqueous solution of NaOH with a mass percentage concentration of 8-12%. The second alkalization is performed at a temperature of 25-40℃ for 50-60 minutes.

5. The preparation method according to claim 1, characterized in that, In step S3, the etherifying agent for the etherification treatment is an aqueous solution of sodium chloroacetate in ethanol; The weight ratio of material B to the etherifying agent is (10-15):(4-7). The volume fraction of sodium chloroacetate in the ethanol aqueous solution is 15-20%.

6. The preparation method according to claim 5, characterized in that, In step S3, the etherification process is as follows: first, the temperature is 30-40℃ for 30-40 min, then the temperature is 50-60℃ for 30-60 min, and then the temperature is raised to 70-80℃ for 20-30 min.

7. A modified sodium carboxymethyl cellulose, characterized in that, The modified sodium carboxymethyl cellulose was prepared by the preparation method described in steps 1 to 6.