Preparation method of antibacterial deodorizing water-absorbing resin

Abstract

The present application relates to the technical field of resin preparation, more particularly, it relates to a preparation method of antibacterial and deodorizing water-absorbing resin, 100 parts by weight of acrylic water-absorbing resin matrix is placed in an inert gas environment, pulse ozone supply is adopted, an activated matrix with non-uniform peroxide distribution on the surface is obtained, the activated matrix is dispersed in a first monomer mixed solution, and a primary asymmetric grafting product is obtained through stirring reaction; a second monomer mixed solution is added to the reaction system, stirring reaction is carried out, after the reaction is completed, the final product is washed and dried, and the antibacterial and deodorizing water-absorbing resin is obtained. The present application has antibacterial ability and good water absorption performance.

Description

Technical Field

[0001] This invention relates to the technical field of resin preparation, and more specifically, to a method for preparing an antibacterial, deodorizing, and water-absorbing resin. Background Technology

[0002] Superabsorbent polymer (SAP) is a polymer material with high absorbency and water retention capabilities, widely used in diapers, sanitary napkins, medical dressings, agriculture, horticulture, and other fields. As people's demands for quality of life and hygiene increase, basic absorbency alone is no longer sufficient to meet market needs. Especially in the hygiene products sector, in addition to efficient liquid absorption, effective odor control and inhibition of bacterial growth have become particularly important.

[0003] Existing technologies for imparting deodorizing and antibacterial functions to absorbent resins typically involve adding or introducing substances with deodorizing and antibacterial activities into the resin. For example, CN116589812A discloses an antibacterial absorbent resin with deodorizing properties and its preparation method. This involves surface crosslinking of an acrylic absorbent resin semi-finished product, followed by the introduction of an organic-inorganic acid salt composition and an antibacterial agent to impart these functions. This patent mentions using alkane compounds to treat the semi-finished product to address the issue of differential swelling of the crosslinked layers during the water absorption process. Another example is CN116584483A, which discloses an antibacterial deodorant for superabsorbent resins and its preparation method. This provides an antibacterial deodorant composition composed of peroxide, active benzenesulfonate, double-chain quaternary ammonium salt, and optionally a base. This composition can be added to superabsorbent resins to impart antibacterial and deodorizing capabilities. This patent focuses on the rapid and efficient removal of transient odor sources through the generation of peracid from peroxide and active benzenesulfonate.

[0004] However, existing modification methods still have some technical problems and limitations. First, the method of adding or introducing functional components into the absorbent resin, as used in the aforementioned existing technologies, may cause these functional components to dissolve in the liquid during water absorption, thus affecting the durability of its deodorizing and antibacterial effects. This dissolution not only reduces the product's lifespan and effectiveness but may also lead to potential safety and environmental problems. Second, to achieve broad-spectrum deodorization and antibacterial functions effective against a variety of complex odor sources and microorganisms, it is often necessary to introduce multiple functional components with different mechanisms of action. This not only increases the complexity of technical implementation, potentially leading to cumbersome processes and higher production costs, but also makes it difficult to precisely control the interactions between different components, which may affect their synergistic effect. For example, CN116584483A optimizes the mass ratio of peroxide, active benzenesulfonate, and alkali to ensure the generation of sufficient peracid for effective deodorization, but this may require precise control in practical applications. In addition, introducing additional functional components into the absorbent resin may affect its original water absorption properties, such as water absorption ratio and water absorption rate. Functional components may occupy absorbent space, block liquid channels, or affect the crosslinking structure and swelling properties of the absorbent resin itself, thereby reducing its core absorbent capacity and impacting the overall performance and application range of the product. CN116589812A mentions solutions to the problem of crosslinking layer cracking or insufficient restriction of linear polymer migration during the swelling process of absorbent resins, indicating that existing technologies still face challenges in maintaining excellent absorbent performance. While existing technologies attempt to address some problems through methods such as surface crosslinking,

[0005] CN116589812A mentions that by controlling the mixing of antibacterial agents with aqueous solutions of organic acid salts and then mixing them with surface-crosslinked water-absorbing resins, the non-dissolution of antibacterial agents can be improved and the anti-yellowing properties can be enhanced. However, how to effectively solve the non-dissolution of functional components, achieve broad-spectrum and long-lasting functional effects while maintaining excellent water absorption properties remains a technical challenge that urgently needs to be addressed in this field.

[0006] Therefore, how to provide a water-absorbing resin that combines high efficiency, long-lasting and broad-spectrum deodorization and antibacterial functions without significantly affecting its original excellent water absorption performance is a challenge currently facing technological development. Summary of the Invention

[0007] Therefore, the purpose of this invention is to provide a method for preparing an antibacterial and deodorizing water-absorbing resin, which has the characteristics of antibacterial ability and good water absorption performance.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for preparing an antibacterial, deodorizing, and absorbent resin includes the following steps:

[0010] S1. Pulse activation treatment of substrate surface: 100 parts by weight of acrylic water-absorbing resin substrate are placed in an inert gas environment and ozone is supplied in a pulsed manner. The ozone concentration is periodically changed between 50-120 ppm. The treatment temperature is 25-30℃ and the total treatment time is 10-25 minutes to obtain an activated substrate with a non-uniform peroxide distribution on the surface. The peroxide content is 1.0-2.0 μmol / cm².

[0011] S2. First-stage asymmetric grafting polymerization: The activated matrix is ​​dispersed in a first monomer mixture, and the first monomer mixture is stirred and reacted at 62-68°C for 1.5-2.5 hours under nitrogen protection to obtain the primary asymmetric grafting product.

[0012] The first monomer mixture includes a chemically reacted deodorizing monomer, a physically adsorbed deodorizing monomer, and a sodium persulfate initiator; the chemically reacted deodorizing monomer is sodium acrylate, and the physically adsorbed deodorizing monomer is β-cyclodextrin methacrylate;

[0013] S3, Second-stage functional composite grafting: Add the second monomer mixture to the reaction system of step S2, and stir the reaction at 75-82℃ for 2.5-3.5 hours; the second monomer mixture includes a physically adsorbed deodorizing monomer, a cationic antibacterial monomer, and a microenvironment regulating monomer.

[0014] The cationic antibacterial monomer is methacryloyloxyethyltrimethylammonium chloride, and the microenvironment regulating monomer is glycidyl methacrylate.

[0015] S4. Post-processing: After the reaction is completed, the final product is washed and dried to obtain the antibacterial, deodorizing, and water-absorbing resin.

[0016] The present invention is further configured such that: the acrylic water-absorbing resin matrix is ​​sodium polyacrylate resin with a crosslinking degree of 3-6% and a weight-average molecular weight of... Within this range, the particle size ranges from 100 to 500 μm;

[0017] The inert gas is high-purity nitrogen with a dew point below -40°C and an oxygen content ≤0.1 vol%.

[0018] The concentration change pattern of the pulsed ozone supply is as follows: with a cycle of 5 minutes, the ozone concentration first increases linearly from 50 ppm to 120 ppm within 1 minute, is maintained for 2 minutes, and then decreases linearly back to 50 ppm within 2 minutes.

[0019] The present invention is further configured such that: in the first monomer mixture, the chemically reacted deodorizing monomer accounts for 75-90 wt% of the total weight of the monomers, the physically adsorbed deodorizing monomer accounts for 8-12 wt% of the total weight of the monomers, and the weight ratio of the two is (9.5-10.5):1;

[0020] The first monomer mixture uses deionized water as a solvent, and the total monomer concentration is 20±1wt%.

[0021] The amount of sodium persulfate initiator added is 0.30 ± 0.05 wt% of the total weight of the first monomer;

[0022] The reaction atmosphere is nitrogen protection, and the dissolved oxygen content in the system is controlled to be ≤0.3ppm by nitrogen bubbling.

[0023] The present invention is further configured such that the reaction conditions in step S2 are:

[0024] The mixing is carried out using a mechanical mixer with anchor blades, and the mixing speed is controlled at 180-220 rpm.

[0025] The reaction temperature linearly increased from room temperature (25±2℃) to 65±0.5℃ within the first 15 minutes, and then remained at a constant temperature for 2±0.1 hours.

[0026] The present invention is further configured such that in step S3:

[0027] In the second monomer mixture, the physical adsorption deodorizing monomer accounts for 45-55 wt% of the total monomer weight, the cationic antibacterial monomer accounts for 32-38 wt% of the total monomer weight, and the microenvironment regulation monomer accounts for 10-15 wt% of the total monomer weight. The preferred weight ratio of the physical adsorption deodorizing monomer, the cationic antibacterial monomer, and the microenvironment regulation monomer is 50:35:15.

[0028] The pH value of the reaction system was monitored by an online pH meter and stabilized at 7.0±0.1 by automatically adding 0.1M NaOH aqueous solution.

[0029] The present invention is further configured such that the ratio of the total monomer content to the matrix weight in the two-stage grafting is:

[0030] In step S2, the total weight of the first monomer accounts for 12 ± 1% of the weight of the matrix.

[0031] In step S3, the total weight of the second monomer accounts for 8 ± 0.5% of the weight of the matrix.

[0032] The present invention is further configured such that: an initiator system is used in the reaction processes of steps S2 and S3, and the initiator system and its usage are specifically as follows:

[0033] In the reaction process of step S2, sodium persulfate initiator is used and ultraviolet irradiation is performed. The ultraviolet light source has a wavelength of 365±2nm and a light intensity of 18-22mW / cm².

[0034] At the beginning of step S3, a composite initiation system is added to the system. The composite initiation system includes a photoinitiator and a redox initiator. The photoinitiator is 2-hydroxy-2-methylphenylacetone, and the redox initiator is composed of ammonium persulfate and N,N,N',N'-tetramethylethylenediamine.

[0035] The total amount of photoinitiator added is 0.05±0.01wt% of the total weight of the second monomer; the redox initiator is freshly prepared before use, wherein the molar ratio of ammonium persulfate to N,N,N',N'-tetramethylethylenediamine is 1:(0.75±0.05), and it is added by constant-rate dropping within the first 20 minutes after the start of the reaction in step S3.

[0036] The present invention is further configured such that the washing process in step S4 includes:

[0037] The product after the reaction was completed was washed with an aqueous solution containing 2.5 wt% sodium chloride. Each wash was soaked and stirred for 20 minutes, and the process was repeated 4 times.

[0038] After each washing, solid-liquid separation was performed by centrifugation or vacuum filtration.

[0039] The present invention is further configured such that the drying process in step S4 adopts a three-stage procedure:

[0040] First stage: Drying in a forced-air environment at 45±2℃ for 1.5±0.2 hours;

[0041] Second stage: Vacuum drying at 60±1℃ for 6±0.3 hours;

[0042] The third stage: vacuum drying at 75±2℃ for 1.5±0.2 hours until the moisture content of the material is less than 3wt%.

[0043] The present invention is further configured such that: after the washing process in step S4 is completed, but before the drying process in step S4 is performed, a functional gradient embedding step is also included:

[0044] Add 1.2 ± 0.1 wt% of an aqueous dispersion of silica nanoparticles, with an average particle size of 30-40 nm, to the filter cake product.

[0045] The suspension was stirred at 60-65℃ for 45±5 minutes to allow the nanoparticles to be embedded into the grafted layer in a gradient distribution through capillary action and adsorption; then a three-stage drying process was carried out.

[0046] Compared with the shortcomings of the prior art, the beneficial effects of the present invention are as follows:

[0047] By simultaneously grafting chemically reactive deodorizing monomers (such as sodium acrylate / sodium methacrylate) and physically adsorbent deodorizing monomers (methacrylic acid-β-cyclodextrin ester), it combines two deodorizing mechanisms: chemical neutralization, reaction, and physical inclusion and adsorption. It exhibits a broad-spectrum and highly efficient deodorizing ability that synergistically enhances various odor molecules, including acidic, alkaline, and neutral ones.

[0048] The grafted cationic antibacterial monomers endow the material with inherent antibacterial activity that is not easily migrated or lost from the material. They can effectively inhibit the growth of bacteria after water absorption, reduce secondary odors caused by bacterial reproduction at the source, and provide a more lasting antibacterial and deodorizing effect. Attached Figure Description

[0049] Figure 1 This is a flowchart of the present invention;

[0050] Figure 2 This is a graph showing the change in liquid absorption volume over time according to the present invention. Detailed Implementation

[0051] The preparation method of the antibacterial, deodorizing, and water-absorbing resin of the present invention will be further described.

[0052] Example 1:

[0053] S1. Surface pulse activation treatment of the matrix: Place 100 grams of sodium polyacrylate resin matrix with a particle size of 200-300μm in a glove box and introduce high-purity nitrogen gas with a dew point below -40℃ and an oxygen content ≤0.1vol% to ensure that the environment is inert.

[0054] The system temperature was controlled at 28℃. Ozone was supplied to the glove box through a pulse ozone generator. The ozone concentration change pattern was as follows: with a cycle of 5 minutes, the ozone concentration first increased linearly from 60ppm to 100ppm within 1 minute, was maintained for 2 minutes, and then decreased linearly back to 60ppm within 2 minutes.

[0055] The pulsed ozone supply was continued for a total treatment time of 20 minutes. After treatment, the ozone supply was turned off, and nitrogen was continuously purged for 5 minutes to obtain an activated substrate with a non-uniform peroxide distribution on the surface. The peroxide content on the surface of the activated substrate was determined to be approximately 1.5 μmol / cm² by chemical titration.

[0056] S2, First-stage asymmetric graft polymerization: 100 grams of the activated matrix prepared in step S1 is added to a reactor equipped with a stirring, temperature control, gas protection and monomer dropping device.

[0057] Preparation of the first monomer mixture: Dissolve 9.96 g of sodium acrylate (83 wt% of the total weight of the first monomer) and 1.20 g of β-cyclodextrin methacrylate (10 wt% of the total weight of the first monomer) in 48 g of deionized water, and adjust the pH to near neutral by adding a small amount of 0.1 M NaOH solution. Total monomer concentration: (9.96 + 1.20) / (48 + 9.96 + 1.20) 100% ≈ 19.6 wt%.

[0058] Transfer the first monomer mixture prepared in step S2 to a dropping funnel.

[0059] Nitrogen gas is introduced into the reactor for bubbling deoxygenation, and the dissolved oxygen content in the system is controlled to be ≤0.3ppm.

[0060] Turn on the stirrer and set the stirring speed to 200 rpm. Start the heating and linearly raise the temperature of the reactor from room temperature (about 25°C) to 65±0.5°C within the first 15 minutes.

[0061] Once the temperature reached 65℃, the first monomer mixture was added dropwise to the reactor, and an ultraviolet light source (wavelength 365nm, light intensity 20mW / cm²) was turned on for irradiation during the reaction. Simultaneously, 0.036 g of sodium persulfate initiator (0.30 wt% of the total weight of the first monomer) was dissolved in a small amount of deionized water and added dropwise to the reactor. After the addition was complete, the reaction was maintained at 65±0.5℃ for 2±0.1 hours.

[0062] S3. Second-stage functional composite grafting: In the reaction system of step S2, a second monomer mixture is prepared: the total monomer weight accounts for 8% of the matrix weight, i.e., 8 grams. This includes 4 grams (50 wt%) of β-cyclodextrin methacrylate, 2.8 grams (35 wt%) of methacryloyloxyethyltrimethylammonium chloride, and 1.2 grams (15 wt%) of glycidyl methacrylate. These monomers are dissolved in an appropriate amount of deionized water to make the concentration of the second monomer mixture approximately 20 wt%.

[0063] Transfer the second monomer mixture prepared in step S3 to a dropping funnel. Raise the temperature of the reactor to 80°C.

[0064] At the start of reaction S3, the composite initiation system is added to the system. Prepare the photoinitiator solution: Dissolve 0.004 g of 2-hydroxy-2-methylphenylacetone (0.05 wt% of the total weight of the second monomer) in a small amount of ethanol. Prepare the redox initiator solution (freshly prepared before use): Dissolve 0.0057 g of ammonium persulfate and 0.0039 g of N,N,N',N'-tetramethylethylenediamine in a small amount of deionized water (molar ratio approximately 1:0.75).

[0065] Begin the dropwise addition of the second monomer mixture while simultaneously irradiating with a UV light source. During the first 20 minutes after the start of the second monomer mixture dropwise addition, add the redox initiator solution using a constant-rate dropping method. The photoinitiator solution is added simultaneously with the second monomer mixture.

[0066] The reaction was stirred at 75-82℃ (80℃ in this example) for 2.5-3.5 hours (3 hours in this example). During this period, the pH value of the system was monitored by an online pH meter, and 0.1M NaOH aqueous solution was automatically added to stabilize it at 7.0±0.1.

[0067] S4. Post-processing: After the reaction is complete, stop heating and stirring.

[0068] Functionally graded embedding: 1.2 wt% of an aqueous dispersion of silica nanoparticles with a particle size of 35 nm (solid content approximately 25%) was added to the filter cake product, i.e., 1.2 g solid content / 25% = 4.8 g dispersion. The product and nanoparticle dispersion were mixed in a stirred container, and the suspension was stirred at 62 °C for 45 minutes.

[0069] Washing: The above suspension is subjected to solid-liquid separation (e.g., vacuum filtration). The filter cake product is washed with an aqueous solution containing 2.5 wt% sodium chloride, soaking and stirring for 20 minutes each time, repeated 4 times. After each wash, solid-liquid separation is performed by centrifugation or vacuum filtration.

[0070] Drying: First stage: Place the washed product in a forced-air drying oven and dry it at 45°C for 1.5 hours.

[0071] Second stage: Transfer the product to a vacuum drying oven and dry it under vacuum at 60°C for 6 hours.

[0072] The third stage: vacuum drying at 75°C for 1.5 hours until the moisture content of the material is less than 3wt%.

[0073] The dried product is crushed and sieved to obtain an antibacterial, deodorizing, and water-absorbing resin product.

[0074] Example 2

[0075] Base: Same as Example 1.

[0076] Pulse activation: Inert gas as in Example 1. Pulse ozone supply: A 5-minute cycle is used, during which the ozone concentration first increases linearly from 50 ppm to 80 ppm within 1 minute, is maintained for 2 minutes, and then linearly decreases back to 50 ppm within 2 minutes. The treatment temperature is 25°C, and the total treatment time is 15 minutes.

[0077] First stage of grafting:

[0078] First monomer mixture: Dissolve 9 g of sodium acrylate (75 wt% of the total weight of the first monomer) and 1.44 g of β-cyclodextrin methacrylate (12 wt% of the total weight of the first monomer) in 48 g of deionized water. The rest is the same as in Example 1.

[0079] The amount of sodium persulfate initiator added is 0.30 wt% of the total weight of the first monomer.

[0080] The rest is the same as in Example 1. The reaction was carried out at a constant temperature for 2 hours.

[0081] Second stage of grafting:

[0082] The second monomer mixture consists of 3.6 g (45 wt%) of β-cyclodextrin methacrylate, 3.04 g (38 wt%) of methacryloyloxyethyltrimethylammonium chloride, and 1.2 g (15 wt%) of glycidyl methacrylate. The remainder is the same as in Example 1.

[0083] The composite initiation system is the same as in Example 1.

[0084] The reaction temperature was 75°C, and the reaction time was 2.5 hours. The pH was controlled in the same manner as in Example 1.

[0085] S4 post-processing: No functional gradient embedding. Washing and drying are the same as in Example 1.

[0086] Example 3

[0087] Base: Same as Example 1.

[0088] Pulse activation: Inert gas as in Example 1. Pulse ozone supply: A 5-minute cycle is used, during which the ozone concentration first increases linearly from 90 ppm to 120 ppm within 1 minute, is maintained for 2 minutes, and then linearly decreases back to 90 ppm within 2 minutes. The treatment temperature is 30°C, and the total treatment time is 20 minutes.

[0089] First stage of grafting:

[0090] First monomer mixture: Dissolve 10.8 g of sodium acrylate (90 wt% of the total weight of the first monomer) and 0.96 g of β-cyclodextrin methacrylate (8 wt% of the total weight of the first monomer) in 48 g of deionized water. The rest is the same as in Example 1.

[0091] The amount of sodium persulfate initiator added was 0.30 wt% of the total weight of the first monomer, and the rest was the same as in Example 1. The reaction was carried out at a constant temperature for 2.1 hours.

[0092] Second stage of grafting:

[0093] The second monomer mixture consists of 4.4 g (55 wt%) of β-cyclodextrin methacrylate, 2.56 g (32 wt%) of methacryloyloxyethyltrimethylammonium chloride, and 0.8 g (10 wt%) of glycidyl methacrylate. The remainder is the same as in Example 1.

[0094] The composite initiation system is the same as in Example 1.

[0095] The reaction temperature was 82°C, and the reaction time was 3.5 hours. The pH was controlled in the same manner as in Example 1.

[0096] Post-processing: Functionally graded embedding. Same as Example 1. Washing and drying are the same as in Example 1.

[0097] Control group 1 (no pulse activation)

[0098] Base: Same as Example 1.

[0099] S1. Substrate Surface Treatment: Place 100g of substrate in an environment purged with high-purity nitrogen gas (dew point below -40℃, oxygen content ≤0.1 vol%). Maintain a continuous ozone supply to a constant ozone concentration of 80 ppm. The treatment temperature is 28℃, and the total treatment time is 20 minutes. After treatment, turn off the ozone supply and continue purging with nitrogen gas for 5 minutes.

[0100] S2, First stage grafting: Same as Example 1.

[0101] S3. Second stage grafting: Same as Example 1.

[0102] S4. Post-processing: Same as Example 1 (including functional gradient embedding).

[0103] Control group 2 (single-stage grafting)

[0104] Base: Same as Example 1.

[0105] S1, Pulse activation: Same as in Example 1.

[0106] S2. Graft polymerization: 100 grams of the activated matrix prepared in step S1 is added to a reactor equipped with a stirring, temperature control, gas protection and monomer dropping device.

[0107] Prepare the monomer mixture: The total monomer weight accounts for 12% of the matrix weight, i.e., 12 grams. This includes 9.96 grams of sodium acrylate and 1.20 grams of β-cyclodextrin methacrylate. Dissolve these monomers in 48 grams of deionized water.

[0108] The monomer mixture was transferred to a dropping funnel. Nitrogen gas was introduced for bubbling deoxygenation, controlling the dissolved oxygen content in the system to ≤0.3 ppm. Stirring was started at 200 rpm, and heating was initiated to raise the reactor temperature to 65°C. Once the temperature reached 65°C, the monomer mixture was added dropwise to the reactor, and ultraviolet light was applied during the reaction. Simultaneously, 0.036 g of sodium persulfate initiator was dissolved in a small amount of deionized water and added dropwise to the reactor. After the addition was complete, the reaction was maintained at 65°C for 2.1 hours.

[0109] S3, Second Stage Functional Composite Grafting: This step is omitted.

[0110] S4. Post-processing: Same as Example 1 (including functional gradient embedding).

[0111] Control group 3 (homogeneous grafting with conventional chemical initiators)

[0112] Base: Same as Example 1.

[0113] S1. Surface treatment of the substrate: This step is omitted. Place 100 grams of substrate directly into the reaction vessel.

[0114] Graft polymerization: 100 grams of matrix are added to a reactor equipped with stirring, temperature control and gas protection.

[0115] Preparation of the monomer mixture: The total monomer weight accounts for 20% of the matrix weight, i.e., 20 grams. This includes 9.96 grams of sodium acrylate (49.8 wt% of total monomers), 4 grams of β-cyclodextrin methacrylate (20 wt%), 2.8 grams of methacryloyloxyethyltrimethylammonium chloride (14 wt%), and 1.2 grams of glycidyl methacrylate (6 wt%). Dissolve these monomers in an appropriate amount of deionized water to achieve a monomer concentration of approximately 20 wt%.

[0116] Introduce nitrogen gas for bubbling deoxygenation and start stirring. Raise the temperature of the reactor to 70°C.

[0117] 0.06 g of sodium persulfate initiator (0.30 wt% of the total monomer weight) was dissolved in a small amount of deionized water and added to the reactor in one go. Then the monomer mixture was added in one go, and the reaction was carried out at 70°C for 5 hours.

[0118] S4. Post-processing: Same as Example 1 (including functional gradient embedding).

[0119] Control group 4 (without functionally graded embeddings)

[0120] The preparation steps are the same as in Example 1, but the functional gradient embedding in step S4 is omitted, that is, washing and drying are performed directly after the reaction is completed.

[0121] The performance of the absorbent resin products prepared in Examples 1-3 and Control Groups 1-4 was tested. The results are shown in Table 1 below:

[0122]

[0123] As can be seen from Table 1 above:

[0124] Example 1 (best practice) exhibits excellent overall performance in terms of liquid absorption rate, liquid absorption volume, water retention, deodorization and antibacterial properties.

[0125] Compared with control group 1, pulse activation treatment (Examples 1-3) can obtain a higher surface peroxide content, thereby improving grafting rate and product performance.

[0126] Compared with control group 2, the two-stage asymmetric grafting (Examples 1-3) can more effectively combine multiple functional monomers and significantly improve deodorization and antibacterial performance.

[0127] Compared with control group 3, the pulse activation and asymmetric two-stage grafting method of the present invention (Examples 1-3) can significantly improve the grafting rate and various functional performances, overcoming the limitations of traditional homogeneous grafting.

[0128] Compared with control group 4, functionally graded embedding (Examples 1 and 3) had little effect on deodorization and antibacterial performance, but significantly improved liquid absorption rate and water retention performance. This was attributed to the gradient distribution of silica nanoparticles in the grafted layer optimizing the liquid transport channels and structural stability.

[0129] The products prepared in Examples 2 and 3 at the end of the ozone concentration range had slightly lower performance than those in Example 1, but were still superior to all comparative examples, indicating that the parameters within the scope of the claims can achieve good results.

[0130] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any ordinary changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an antibacterial, deodorizing, and absorbent resin, characterized in that, Includes the following steps: S1. Pulse activation treatment of substrate surface: 100 parts by weight of acrylic water-absorbing resin substrate are placed in an inert gas environment and ozone is supplied in a pulsed manner. The ozone concentration is periodically changed between 50-120 ppm. The treatment temperature is 25-30℃ and the total treatment time is 10-25 minutes. An activated substrate with non-uniform peroxide distribution on the surface is obtained. The peroxide content is 1.0-2.0 μmol / cm². S2, First-stage asymmetric grafting polymerization: The activated matrix is ​​dispersed in the first monomer mixture, and the first monomer mixture is stirred and reacted at 62-68℃ for 1.5-2.5 hours under nitrogen protection to obtain the primary asymmetric grafting product; The first monomer mixture includes a chemically reacted deodorizing monomer, a physically adsorbed deodorizing monomer, and a sodium persulfate initiator; the chemically reacted deodorizing monomer is sodium acrylate, and the physically adsorbed deodorizing monomer is β-cyclodextrin methacrylate; In the first monomer mixture, sodium acrylate accounts for 75-90 wt% of the total monomer weight, and β-cyclodextrin methacrylate accounts for 8-12 wt% of the total monomer weight. The first monomer mixture used deionized water as solvent, with a total monomer concentration of 20 ± 1 wt%. The amount of sodium persulfate initiator added is 0.30 ± 0.05 wt% of the total weight of the first monomer; The reaction atmosphere is nitrogen protection, and the dissolved oxygen content in the system is controlled to be ≤0.3ppm by nitrogen bubbling; S3, Second-stage functional composite grafting: Add the second monomer mixture to the reaction system of step S2, and stir the reaction at 75-82℃ for 2.5-3.5 hours; The second monomer mixture comprises a physically adsorbed deodorizing monomer, a cationic antibacterial monomer, and a microenvironment-regulating monomer. The cationic antibacterial monomer is methacryloyloxyethyltrimethylammonium chloride, the microenvironment-regulating monomer is glycidyl methacrylate, and the physically adsorbed deodorizing monomer is β-cyclodextrin methacrylate. In the second monomer mixture, β-cyclodextrin methacrylate accounts for 45-55 wt% of the total monomer weight, methacryloyloxyethyltrimethylammonium chloride accounts for 32-38 wt% of the total monomer weight, and glycidyl methacrylate accounts for 10-15 wt% of the total monomer weight. The pH value of the reaction system was monitored by an online pH meter and automatically controlled at 7.0±0.1 by adding 0.1M NaOH aqueous solution. The total monomer content to matrix weight ratio of the two-stage grafting is: In step S2, the total weight of the first monomer accounts for 12 ± 1% of the weight of the matrix. In step S3, the total weight of the second monomer accounts for 8 ± 0.5% of the weight of the matrix. S4. Post-treatment: After the reaction is completed, the final product is washed and dried to obtain antibacterial, deodorizing, and water-absorbing resin.

2. The method for preparing an antibacterial, deodorizing, and absorbent resin according to claim 1, characterized in that, The acrylic water-absorbing resin matrix is ​​sodium polyacrylate resin with a crosslinking degree of 3-6% and a weight-average molecular weight of 5×10⁻⁶. 5 -1×10 6 Within this range, the particle size ranges from 100 to 500 μm; The inert gas is high-purity nitrogen with a dew point below -40°C and an oxygen content ≤0.1 vol%. The concentration change pattern of the pulsed ozone supply is as follows: with a cycle of 5 minutes, the ozone concentration first increases linearly from 50 ppm to 120 ppm within 1 minute, is maintained for 2 minutes, and then decreases linearly back to 50 ppm within 2 minutes.

3. The method for preparing an antibacterial, deodorizing, and absorbent resin according to claim 2, characterized in that, The reaction conditions in step S2 are as follows: The mixing is carried out using a mechanical mixer with anchor blades, and the mixing speed is controlled at 180-220 rpm. The reaction temperature linearly increased from room temperature (25±2℃) to 65±0.5℃ within the first 15 minutes, and then remained at a constant temperature for 2±0.1 hours.

4. The method for preparing an antibacterial, deodorizing, and absorbent resin according to claim 3, characterized in that, An initiator system is used in the reaction processes of steps S2 and S3. The initiator system and its usage are as follows: In the reaction process of step S2, sodium persulfate initiator is used and ultraviolet irradiation is performed. The ultraviolet light source has a wavelength of 365±2nm and a light intensity of 18-22mW / cm². At the beginning of step S3, a composite initiation system is added to the system. The composite initiation system includes a photoinitiator and a redox initiator. The photoinitiator is 2-hydroxy-2-methylphenylacetone, and the redox initiator is composed of ammonium persulfate and N,N,N',N'-tetramethylethylenediamine. The total amount of photoinitiator added is 0.05±0.01wt% of the total weight of the second monomer; the redox initiator is freshly prepared before use, wherein the molar ratio of ammonium persulfate to N,N,N',N'-tetramethylethylenediamine is (0.75±0.05):1, and it is added by constant-rate dropping within the first 20 minutes after the start of the reaction in step S3.

5. The method for preparing an antibacterial, deodorizing, and absorbent resin according to claim 4, characterized in that, The washing process in step S4 includes: The product after the reaction was completed was washed with an aqueous solution containing 2.5 wt% sodium chloride. Each wash was soaked and stirred for 20 minutes, and the process was repeated 4 times. After each washing, solid-liquid separation was performed by centrifugation or vacuum filtration.

6. The method for preparing an antibacterial, deodorizing, and absorbent resin according to claim 5, characterized in that, The drying process in step S4 adopts a three-stage procedure: First stage: Drying in a forced-air environment at 45±2℃ for 1.5±0.2 hours; Second stage: Vacuum drying at 60±1℃ for 6±0.3 hours; The third stage: vacuum drying at 75±2℃ for 1.5±0.2 hours until the moisture content of the material is less than 3wt%.

7. The method for preparing an antibacterial, deodorizing, and absorbent resin according to claim 6, characterized in that, After the washing process in step S4 is completed, but before the drying process in step S4 is performed, a functional gradient embedding step is also included: Add 1.2 ± 0.1 wt% of an aqueous dispersion of silica nanoparticles, with an average particle size of 30-40 nm, to the filter cake product. The suspension was stirred at 60-65℃ for 45±5 minutes to allow the nanoparticles to be embedded in the grafted layer in a gradient distribution through capillary action and adsorption; then a three-stage drying process was carried out.

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