Liquid silicon modified polymer water-absorbing resin, its preparation method and application

Abstract

This invention relates to the field of absorbent polymer (SAP) technology, specifically to a liquid silica-modified superabsorbent polymer (SAP), its preparation method, and its applications. The SAP comprises a polyacrylic acid-acrylate crosslinked copolymer and a liquid silica crosslinked mixture. The liquid silica crosslinked mixture includes a crosslinking agent, a silica dispersion, a polyol, and water. The amount of silica added in the silica dispersion is 0.03-0.2% of the mass of the polyacrylic acid-acrylate crosslinked copolymer. This simple and efficient method modifies the absorbent polymer (SAP) while significantly improving its liquid permeability, absorption rate, and flowability, meeting the practical needs of hygiene products.

Description

Technical Field

[0001] This invention relates to the field of absorbent resin technology, specifically to a liquid silicone-modified superabsorbent polymer, its preparation method, and its application. Background Technology

[0002] Superabsorbent polymers (SAPs) have wide applications in hygiene products, agricultural water retention, and industrial dehydration. However, traditional SAPs present several challenges in practical applications. After absorbing water and swelling, traditional SAPs form a dense gel network, leading to pore blockage and hindering the smooth flow of water between gel particles. In hygiene product applications, this can cause backflow and slow drying. Furthermore, because the liquid absorption process of traditional SAPs relies primarily on capillary action and diffusion, the absorption rate is slow and cannot meet the rapid water absorption requirements of emergency treatment and medical care. In addition, most SAP particles are prone to agglomeration and clumping during production, resulting in irregular surface cross-linking and unstable performance.

[0003] To address the aforementioned issues, existing technologies often employ methods such as adding inorganic fillers and altering polymerization processes to modify SAP. For instance, Chinese patent application (publication number CN121495062A) discloses a diatomaceous earth-modified composite superabsorbent polymer and its preparation method. This method primarily improves the resin's water absorption and retention properties by copolymerizing modified diatomaceous earth with acrylic acid and acrylamide. However, these methods have limited modification effects, complex processes, high costs, and are mainly applied in the agricultural field, failing to effectively meet the comprehensive performance requirements of sanitary products for absorbent resins. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a liquid silicone-modified superabsorbent polymer (SAP). This method employs a simple and efficient approach to modify the SAP, significantly improving its liquid permeability, absorption rate, and flowability to meet the practical needs of hygiene products.

[0005] The present invention provides a liquid silica-modified superabsorbent polymer, comprising a polyacrylic acid-acrylate crosslinked copolymer and a liquid silica crosslinked mixture; the liquid silica crosslinked mixture comprises a crosslinking agent, a silica dispersion, a polyol and water; the amount of silica added in the silica dispersion is 0.03-0.2% of the mass of the polyacrylic acid-acrylate crosslinked copolymer.

[0006] Existing superabsorbent polymers (SAPs) can only achieve a single function of water absorption and retention, and cannot simultaneously achieve excellent liquid permeability, rapid liquid absorption rate and stable pressure water retention performance. Furthermore, they cannot solve problems such as gel clogging after water absorption and swelling, liquid backflow, and slow drying speed, making it difficult to meet the comprehensive use needs of hygiene products, medical care and other fields. This application utilizes a polyacrylic acid-acrylate crosslinked copolymer as the matrix, combined with a liquid silica crosslinking mixture consisting of a crosslinking agent, a silica dispersion (the amount of silica added is 0.03-0.2% of the mass of the polyacrylic acid-acrylate crosslinked copolymer), a polyol, and water for surface crosslinking modification. This not only maintains a loose porous network structure after water absorption and swelling, significantly improving the flow efficiency of liquid between gel particles and significantly reducing liquid backflow, keeping the surface of hygiene products dry for a long time; it also significantly improves the compressive strength and pressurized water retention capacity of the gel, firmly locking in moisture under continuous pressure, meeting the high requirements for pressurized water retention in scenarios such as agricultural water retention and industrial dehydration; at the same time, it greatly accelerates the liquid absorption rate, meeting the rapid water absorption needs of emergency treatment and medical care.

[0007] The rationale for this invention is likely as follows: the nano-sized particles in the silica dispersion can form a rigid supporting framework on and inside the SAP, fundamentally avoiding the problem of gel particles clogging pores due to excessive swelling in traditional SAP, thus providing a continuous and stable channel for liquid flow; the liquid silica binds tightly to the SAP matrix through chemical bonding, forming an interpenetrating network structure, which significantly improves the mechanical strength and compression resistance of the gel, resulting in a significant improvement in water retention under pressure; the liquid silica forms uniformly distributed hydrophilic microregions on the SAP surface, reducing the surface tension of water, while the constructed porous channels significantly shorten the diffusion path of water molecules into the SAP, thereby significantly accelerating the liquid absorption rate; through the combined effect of all components, the overall performance of the product is guaranteed.

[0008] In one embodiment, the amount of silica added to the silica dispersion is 0.1-0.143% of the mass of the polyacrylic acid-acrylate crosslinked copolymer.

[0009] In one embodiment, the amount of the liquid silicone crosslinking mixture is 2-5% of the weight of the polyacrylic acid-acrylate crosslinking copolymer.

[0010] In one embodiment, the amount of the liquid silicone crosslinking mixture is 3.5-4% of the weight of the polyacrylic acid-acrylate crosslinking copolymer.

[0011] In one embodiment, the particle size range of the polyacrylic acid-acrylate crosslinked copolymer is 150-850 μm.

[0012] In one embodiment, the method for preparing the polyacrylic acid-acrylate crosslinked copolymer includes the following steps: An aqueous solution of acrylic acid and an internal crosslinking agent were mixed to obtain an aqueous monomer solution. Nitrogen gas was introduced to remove oxygen. An aqueous solution of sodium persulfate and an aqueous solution of L-ascorbic acid were added to initiate polymerization and obtain a hydrogel-like crosslinked polymer. The hydrogel-like crosslinked polymer is pre-crushed to obtain 3-5*3-5cm block material; the block material is added to a granulator for crushing, and a neutralizing agent is added at the same time for neutralization; after drying, grinding and sieving, polyacrylic acid-acrylate crosslinked copolymer is obtained.

[0013] In one embodiment, the mass concentration of the acrylic acid aqueous solution is 20-30%.

[0014] In one embodiment, the mass concentration of the acrylic acid aqueous solution is 26-28%.

[0015] In one embodiment, the internal crosslinking agent comprises polyethylene glycol diacrylate.

[0016] In one embodiment, the amount of the internal crosslinking agent added is 0.08-0.15% of the mass of the acrylic acid aqueous solution.

[0017] In one embodiment, the amount of the internal crosslinking agent added is 0.1-0.12% of the mass of the acrylic acid aqueous solution.

[0018] In one embodiment, the mass concentration of the sodium persulfate aqueous solution is 5-15%.

[0019] In one embodiment, the mass concentration of the sodium persulfate aqueous solution is 8-10%.

[0020] In one embodiment, the mass concentration of the L-ascorbic acid aqueous solution is 2-7%.

[0021] In one embodiment, the mass concentration of the L-ascorbic acid aqueous solution is 4-5%.

[0022] In one embodiment, the mass ratio of the acrylic acid aqueous solution, sodium persulfate aqueous solution, and L-ascorbic acid aqueous solution is 4088:15-25:0.5-3.

[0023] In one embodiment, the mass ratio of the acrylic acid aqueous solution, sodium persulfate aqueous solution, and L-ascorbic acid aqueous solution is 4088:18-20.8:1.5-1.65.

[0024] In one embodiment, the neutralizing agent comprises sodium bicarbonate.

[0025] In one embodiment, the amount of neutralizing agent added is 10-15% of the mass of the acrylic acid aqueous solution.

[0026] In one embodiment, the amount of neutralizing agent added is 12-13.11% of the mass of the acrylic acid aqueous solution.

[0027] In one embodiment, the drying includes the following steps: spreading the neutralized material on a metal mesh and drying it in a hot air dryer at 130-140°C for 100-120 minutes.

[0028] In one embodiment, the liquid silicon crosslinking mixture comprises, by weight, 1-3 parts crosslinking agent, 0.63-4.2 parts silica dispersion, 3-8 parts polyol, and 8-15 parts water.

[0029] In one embodiment, the liquid silicon crosslinking mixture comprises, by weight, 2-2.5 parts of crosslinking agent, 2.1-3 parts of silica dispersion, 5-6 parts of polyol, and 11.9-13 parts of water.

[0030] In one embodiment, the crosslinking agent comprises ethylene glycol diglycidyl ether.

[0031] In one embodiment, the polyol includes at least one of propylene glycol or butanediol.

[0032] In one embodiment, the silica dispersion contains 25-45 wt% silica.

[0033] In one embodiment, the silica dispersion is at least one of Levasil CA330 H or Levasil CA425 H.

[0034] Another aspect of the present invention provides a method for preparing liquid silicone-modified superabsorbent polymer, comprising the following steps: The polyacrylic acid-acrylate crosslinked copolymer and the liquid silicone crosslinked mixture were mixed and treated at 120-130℃ for 30-40 minutes to obtain the liquid silicone modified superabsorbent polymer.

[0035] The third aspect of this invention provides an application of liquid silicone-modified superabsorbent polymer, which is used in agricultural water retention, industrial dehydration, emergency treatment and medical care.

[0036] Beneficial effects 1. This invention provides a liquid silicone-modified superabsorbent polymer (SAP) that uses a simple and efficient method to modify the superabsorbent polymer, while significantly improving the SAP's liquid permeability, absorption rate, and flowability, thus meeting the actual needs of hygiene products.

[0037] 2. This application uses a polyacrylic acid-acrylate crosslinked copolymer as the matrix, combined with a liquid silica crosslinking mixture consisting of a crosslinking agent, a silica dispersion (the amount of silica added is 0.03-0.2% of the mass of the polyacrylic acid-acrylate crosslinked copolymer), a polyol, and water for surface crosslinking modification. This not only maintains a loose porous network structure after water absorption and swelling, significantly improving the flow efficiency of liquid between gel particles, significantly reducing liquid backflow, and keeping the surface of hygiene products dry for a long time; it also significantly improves the compressive strength and pressure water retention capacity of the gel, and can firmly lock in moisture under continuous pressure, meeting the requirements of high pressure water retention in scenarios such as agricultural water retention and industrial dehydration; at the same time, it greatly accelerates the liquid absorption rate, meeting the rapid water absorption needs of emergency treatment and medical care.

[0038] 3. This invention introduces silica into the product system in the form of a stable silica dispersion, which has better dispersibility and compatibility compared to traditional inorganic fillers. It is less prone to agglomeration and can form a uniform modified layer on the SAP surface, ensuring the regularity of surface crosslinking and the consistency of product performance. Moreover, the preparation process is simple, requires no complex equipment, and is suitable for large-scale industrial production. Detailed Implementation

[0039] Example 1 In one aspect, Embodiment 1 of the present invention provides a liquid silicone modified superabsorbent polymer, which, by weight, comprises 100 parts of polyacrylic acid-acrylate crosslinked copolymer and 3.5 parts of liquid silicone crosslinked mixture; the liquid silicone crosslinked mixture, by weight, comprises 2 parts of crosslinking agent, 2.1 parts of silica dispersion, 6 parts of polyol, and 11.9 parts of water.

[0040] The silica dispersion contains 30±1wt% silica and is of the Levasil CA330 H type.

[0041] The preparation method of the polyacrylic acid-acrylate crosslinked copolymer includes the following steps: An aqueous solution of acrylic acid and an internal crosslinking agent were mixed to obtain an aqueous monomer solution. Nitrogen gas was introduced to remove oxygen. An aqueous solution of sodium persulfate and an aqueous solution of L-ascorbic acid were added to initiate polymerization and obtain a hydrogel-like crosslinked polymer. The hydrogel-like crosslinked polymer is pre-crushed to obtain 4*4cm block material; the block material is added to a granulator for crushing, and a neutralizing agent is added at the same time for neutralization; after drying, grinding and sieving, a polyacrylic acid-acrylate crosslinked copolymer with a particle size range of 150-850μm is obtained.

[0042] The mass concentration of the acrylic acid aqueous solution is 26%.

[0043] The internal crosslinking agent is Wie polyethylene glycol diacrylate.

[0044] The amount of the internal crosslinking agent added is 0.1% of the mass of the acrylic acid aqueous solution.

[0045] The sodium persulfate aqueous solution has a mass concentration of 10%.

[0046] The mass concentration of the L-ascorbic acid aqueous solution is 5%.

[0047] The mass ratio of the acrylic acid aqueous solution, sodium persulfate aqueous solution, and L-ascorbic acid aqueous solution is 4088:20.8:1.65.

[0048] The neutralizing agent is sodium bicarbonate. The amount of the neutralizing agent added is 13.11% of the mass of the acrylic acid aqueous solution.

[0049] The drying process includes the following steps: spreading the neutralized material onto a metal mesh and drying it in a hot air dryer at 130°C for 100 minutes.

[0050] Example 1 of the present invention provides a method for preparing liquid silicone-modified superabsorbent polymer, comprising the following steps: The polyacrylic acid-acrylate crosslinked copolymer and the liquid silicone crosslinked mixture were mixed and treated at 130°C for 30 min to obtain the liquid silicone modified superabsorbent polymer.

[0051] Example 2 Example 2 of the present invention provides a liquid silicone modified superabsorbent polymer and its preparation method. The specific implementation method is the same as that of Example 1, except that the liquid silicone crosslinking mixture, by weight, includes 2 parts of crosslinking agent, 0.63 parts of silica dispersion, 6 parts of polyol, and 13.37 parts of water.

[0052] Example 3 Example 3 of the present invention provides a liquid silica modified superabsorbent polymer and its preparation method. The specific implementation method is the same as that of Example 1, except that the silica content in the silica dispersion is 40 wt%, and the silica type is Levasil CA425 H.

[0053] Example 4 Example 4 of the present invention provides a liquid silicone modified superabsorbent polymer and its preparation method. The specific implementation method is the same as that of Example 3, except that the liquid silicone crosslinking mixture, by weight, includes 2 parts of crosslinking agent, 0.63 parts of silica dispersion, 6 parts of polyol, and 13.37 parts of water.

[0054] Comparative Example 1 Comparative Example 1 of the present invention is a polyacrylic acid-acrylate crosslinked copolymer, and its specific preparation method is the same as that of Example 1.

[0055] Comparative Example 2 Comparative Example 2 of the present invention provides a liquid silicone modified superabsorbent polymer and its preparation method. The specific implementation method is the same as that of Example 1, except that the liquid silicone crosslinking mixture, by weight, includes 2 parts of crosslinking agent, 0 parts of silica dispersion, 6 parts of polyol, and 13.7 parts of water.

[0056] Comparative Example 3 Comparative Example 3 of the present invention provides a liquid silicone modified superabsorbent polymer and its preparation method. The specific implementation method is the same as that of Example 1, except that the liquid silicone crosslinking mixture, by weight, includes 2 parts of crosslinking agent, 0 parts of silica dispersion, 0.3 parts of fumed silica, 6 parts of polyol, and 14 parts of water.

[0057] Comparative Example 4 Comparative Example 4 of the present invention provides a liquid silicone modified superabsorbent polymer and its preparation method. The specific implementation method is the same as that of Example 1, except that the liquid silicone crosslinking mixture, by weight, includes 2 parts of crosslinking agent, 6.3 parts of silica dispersion, 6 parts of polyol, and 7.7 parts of water.

[0058] Comparative Example 5 Comparative Example 5 of the present invention provides a liquid silicone modified superabsorbent polymer and its preparation method. The specific implementation method is the same as that of Example 3, except that the liquid silicone crosslinking mixture, by weight, includes 2 parts of crosslinking agent, 6.3 parts of silica dispersion, 6 parts of polyol, and 7.7 parts of water.

[0059] Comparative Example 6 Comparative Example 6 of the present invention provides a liquid silicone modified superabsorbent polymer and its preparation method. The specific implementation method is the same as that of Example 1, except that the liquid silicone crosslinking mixture, by weight, includes 2 parts of crosslinking agent, 0.63 parts of silica dispersion, 0.3 parts of fumed silica, 6 parts of polyol, and 13.07 parts of water.

[0060] Comparative Example 7 Comparative Example 7 of the present invention provides a liquid silicone modified superabsorbent polymer and its preparation method. The specific implementation method is the same as that of Example 1, except that the liquid silicone crosslinking mixture, by weight, includes 2 parts of crosslinking agent, 2.1 parts of silica dispersion, 0.3 parts of fumed silica, 6 parts of polyol, and 11.6 parts of water.

[0061] Comparative Example 8 Comparative Example 8 of the present invention provides a liquid silicone modified superabsorbent polymer and its preparation method. The specific implementation method is the same as that of Example 1, except that the liquid silicone crosslinking mixture, by weight, includes 2 parts of crosslinking agent, 6.3 parts of silica dispersion, 0.3 parts of fumed silica, 6 parts of polyol, and 7.4 parts of water.

[0062] Comparative Example 9 Comparative Example 9 of the present invention provides a liquid silicone modified superabsorbent polymer and its preparation method. The specific implementation method is the same as that of Example 3, except that the liquid silicone crosslinking mixture, by weight, includes 2 parts of crosslinking agent, 0.63 parts of silica dispersion, 0.3 parts of fumed silica, 6 parts of polyol, and 13.07 parts of water.

[0063] Comparative Example 10 Comparative Example 10 of the present invention provides a liquid silicone modified superabsorbent polymer and its preparation method. The specific implementation method is the same as that of Example 3, except that the liquid silicone crosslinking mixture, by weight, includes 2 parts of crosslinking agent, 2.1 parts of silica dispersion, 0.3 parts of fumed silica, 6 parts of polyol, and 11.6 parts of water.

[0064] Comparative Example 11 Comparative Example 11 of the present invention provides a liquid silicone modified superabsorbent polymer and its preparation method. The specific implementation method is the same as that of Example 3, except that the liquid silicone crosslinking mixture, by weight, includes 2 parts of crosslinking agent, 6.3 parts of silica dispersion, 0.3 parts of fumed silica, 6 parts of polyol, and 7.4 parts of water.

[0065] Performance testing The products prepared in the examples and comparative examples were subjected to the following tests. The test methods are as follows, and the test results are shown in Table 1.

[0066] 1. CRC and FSC The weighed sample (the product prepared in the examples and comparative examples, the same below) was placed in a cloth bag, and then the cloth bag was immersed in the liquid to absorb the liquid. After hanging to cool for a specified time and centrifuging, the amount of liquid remaining was tested. The specific steps are as follows: (1) Calibrate balance 1 and balance 2.

[0067] (2) Weigh 0.2000g (±0.0050g) of the sample into each tea bag using balance 1. Weigh two parallel samples for each sample and record the weight as m. s1 m s2 .

[0068] (3) Prepare two empty cloth bags.

[0069] (4) Pour a certain amount of 0.9% saline solution into the plastic box and adjust the temperature of the solution to 25°C. Each liter of such solution can soak a maximum of 10 such cloth bags, and they need to be replaced after use.

[0070] (5) Immerse the cloth bag in the test solution, then use a glass rod to press the cloth bag below the liquid surface, and remove air bubbles from the bag using an appropriate method. If there are many cloth bags, ensure that there is a gap between every two cloth bags.

[0071] (6) Perform the same steps as in step 6 for the two empty cloth bags.

[0072] (7) After 30 (±1) min, remove the cloth bag containing SAP and the empty cloth bag from the saline solution.

[0073] (8) Clip one side of the cloth bag and hang it to dry for 10 minutes. Then, weigh each cloth bag using a balance and record the weight. The weight of the two empty bags is m. a1 and m a2 The weights of the cloth bags containing SAP superabsorbent powder were m w1 and m w2 .

[0074] (9) Place the cloth bag containing the sample and the empty cloth bag into the centrifuge. Place the empty bag and the bag containing the sample symmetrically to maintain balance. (10) After 3 minutes (±10 seconds), turn off the centrifuge and remove the cloth bag containing SAP and the empty cloth bag from the centrifuge. Weigh each cloth bag after centrifugation using a balance and record the weight. The weight of the two empty bags is m. b1 and m b2 The weights of the cloth bags containing SAP superabsorbent powder were m u1 and m u2 .

[0075] (11) Calculate the average mass of the two empty cloth bags after they have been hung up to dry: m a =(m a1 +m a2 ) / 2 For each sample (i=1 and 2), calculate the free expansion rate (FSC) and express it as a mass fraction (g / g): FSC=(m wi -m a -m si ) / m si In the formula: m si —g represents the weight of the dried sample; m a —g, which is the average weight of the two empty cloth bags after they have been hung up to dry, 0.71g; m wi —g represents the weight of the wet cloth containing the sample after it has been hung up to dry.

[0076] (12) Calculate the average mass of the two empty cloth bags after centrifugation: M b =(m b1 +m b2 ) / 2 For each sample (i=1 and 2), calculate the free expansion ratio (CRC) and express it as a mass fraction (g / g): CRC=(m ui -m b -m si ) / m si In the formula: m si —g represents the weight of the dried sample; m b —g, which is the average weight of the two empty cloth bags after centrifugation, 0.46g; m ui —g represents the weight of the wet cloth bag containing the sample after centrifugation.

[0077] The result is the average of two calculations, accurate to 0.1.

[0078] 2. AS (Vortex Absorption Rate) A certain amount of superabsorbent resin absorbs water in a solution that forms a stable vortex until the vortex disappears; the time required is called the vortex absorption rate of the superabsorbent resin. The specific operation is as follows: (1) Use a pipette to transfer 50 mL of 0.9 wt% physiological saline (the test temperature is controlled to 25.0 ± 0.5 ℃), pour it into a 100 mL beaker, and place the rotor inside.

[0079] (2) Place the beaker on a magnetic stirrer and stir at a speed of 500±5 rpm to ensure that a stable vortex is produced on the liquid surface.

[0080] (3) Accurately weigh 2.000g (±0.005g) of sample and put it into the vortex. At the same time, start timing with a stopwatch. When the vortex on the liquid surface disappears and the liquid surface becomes horizontal, stop timing.

[0081] 3. 0.7 AUP (Pressure Absorption Capacity) The weighed sample is spread evenly on a filter screen, covering the bottom of a specially designed cylinder. Uniform pressure is then applied to the sample, and the cylinder is placed in a petri dish filled with sodium chloride solution. After one hour of sample absorption, the cylinder is removed from the tray, and the amount of absorbed liquid is measured. The specific procedure is as follows: (1) Weigh (0.900±0.005) g of sample and record its weight as m. s The corresponding surface density of the mesh at the bottom of the test cylinder is 0.032 g / cm³. 2 .

[0082] (2) Place the piston on the cylinder and weigh the entire cylindrical device, recording the weight as m. A (3) Place the filter plate in a petri dish and add 0.9% physiological saline to make the liquid surface level with the surface of the filter plate, 120 mL.

[0083] (4) Place the entire cylindrical equipment on top of the wetted filter paper and leave it for (60±1) min to allow the sample to fully absorb the salt solution.

[0084] (5) Lift the entire cylindrical equipment and remove its cylindrical weight, weigh the cylindrical equipment again and record the weight as m. B .

[0085] (6) Repeat experiments 1-5 to obtain two sets of experimental data.

[0086] (7) Rinse the filter plate with deionized water. (8) Calculation formula: For each sample, calculate its absorption amount under the corresponding pressure W, expressed as a mass fraction (g / g), W = (m B -m A / m S ).

[0087] Where m S The weight of the dried sample to be tested, in g; m A Weight of the drying cylinder, g; m B The weight of the cylinder after absorbing the liquid, in grams; The result is accurate to 0.1 based on the average of the two tests.

[0088] 4. Absorption capacity of pure water and salt water in 1 minute Different SAPs absorb different amounts of water in a non-absorbent state within a certain time period. Therefore, the difference in absorption rate was compared by testing the amount of pure / saline water absorbed by the SAP within 1 minute. The specific operation is as follows: (1) Number the tea bags according to their serial numbers, and put each tea bag into a plastic cup containing 4000mL of pure water / 0.9wt% physiological saline (temperature controlled at 25.0±0.5℃). Soak for 1 minute, then hang to dry for 1 minute. After drying, weigh the tea bags and record the wet weight of the tea bags according to their serial numbers (to two decimal places). This is the blank test. (2) Weigh 1g (±0.0005g) of the sample, record the weight as m1, put the sample into a tea bag, and record the corresponding number.

[0089] (3) Immerse each sealed tea bag into a plastic cup containing 4000~4500ml of pure water / 0.9% saline at 25℃ (test temperature controlled at 25.0±0.5℃). Soak for 1 minute, then hang to dry for 1 minute. During soaking, seal the bag opening with a thermoplastic sealer to prevent SAP leakage. After drying, weigh the bag and record the weight as m2.

[0090] (4) Sample absorption of pure / salt water per minute = (m2) m1 湿袋 ) / m1.

[0091] In the formula: m1——g, which is the weight of the sample taken; m2——g, which is the weight after liquid absorption; m 湿袋 —g represents the weight of the wet tea bag. The average weight is 1.36g for bag #3 and 3.8g for bag #6.

[0092] 5. Three Major Ya Tong Liquid The permeability of different superabsorbent polymers (SAPs) can be distinguished by their ability to permeate liquids through the swelled gel base. After swelling, SAPs retain pore spaces; the permeability of the resin is determined by observing how the test solution permeates through these pores. The specific procedure is as follows.

[0093] (1) Weigh 150g of physiological saline (25℃, 0.9wt%) and pour it into a 250ml beaker.

[0094] (2) Weigh 0.3200 (±0.0005) g of sample (each weighing interval is 10 min) and pour it into a 250 mL beaker containing 150 g of physiological saline.

[0095] (3) Place the 250mL beaker on a magnetic stirrer and stir at 120rpm (±5rpm) for 1min. Then remove it and let it stand for 30min.

[0096] (4) Pour 25℃, 0.9wt% physiological saline into the three-way flow device and open the valve to remove air bubbles in the tube.

[0097] (5) After confirming that there are no air bubbles, place the device on the iron stand and pour 25℃, 0.9wt% saline into the tube up to 4cm above the upper mark.

[0098] (6) Open the valve, press the stopwatch when the salt water reaches the upper mark, and stop the timer when it reaches the lower mark. Measure the time it takes for the salt water to flow through the detection tube and record it as T0.

[0099] (7) After 30 minutes, stir the sample with the back handle of the weighing spoon for 10 seconds, pour the gel and saline in the 250ml beaker into the device, open the valve, filter the excess saline into the beaker, and then transfer the mixture into the device. Repeat this process 2-3 times until the remaining gel in the beaker is completely transferred into the device.

[0100] (8) Open the valve to adjust the liquid level to 4cm above the mark, then close the valve. Place a 125g weight into the device and let it sink freely to the bottom for 1 minute.

[0101] (9) After 1 minute, open the valve. When the salt water reaches the upper mark, press the stopwatch to start the timer. When it reaches the lower mark, stop the timer and record it as T1.

[0102] (10) After the sample test is completed, clean the device.

[0103] (11) Each experiment is repeated in 2 parallels.

[0104] (12) Calculation: T = T1 - T0, unit: s / 20mL, converted to flow rate (mL / min) = 1200 / T 6. Gel bed permeability (GBP) The liquid conductivity of superabsorbent resins under pressure was characterized using gel bed permeability (GBP). The test procedure is as follows: (1) Prepare a 0.9 wt% sodium chloride aqueous solution and keep it at a constant temperature of (25±0.5)℃; (2) Take the sample of the superabsorbent resin to be tested, sieve it through a 106 μm to 850 μm sieve, and accurately weigh 0.9000 g; (3) Spread the sample evenly on the bottom filter screen of the test cylinder with an inner diameter of 6.0 cm and an effective cross-sectional area of ​​28.27 cm²; (4) Slowly add 0.9 wt% sodium chloride solution along the cylinder wall to completely immerse the sample and allow it to swell freely for 60 min to form a stable gel bed; (5) Apply a constant pressure of 2.07 kPa (0.3 psi) above the gel bed and allow it to equilibrate for 1 min; (6) Keep the liquid level constant and record the outflow time of 20.0 mL of test solution through the gel bed. After deducting the blank flow resistance of the device, calculate the volumetric flow rate. (7) Calculate the GBP value using the following formula, unit: ×10 -7 cm³·s·g - ¹: GBP = (F × L × μ) / (A × ΔP) × 10 7 .

[0105] In the formula: F — Volumetric flow rate (cm³ / s); L — Gel bed thickness (cm); μ—Viscosity of physiological saline at 25℃ (Pa) s); A— Cross-sectional area of ​​the test cylinder (cm²); ΔP — Applied pressure (Pa).

[0106] Two parallel tests were conducted. A relative deviation of ≤5% was considered valid, and the average value was taken as the test result.

[0107] Table 1

[0108] Analysis of the data in Table 1 for the examples and comparative examples shows that the products provided in Examples 1-4 have better overall performance than those provided in Comparative Examples 1-11.

Claims

1. A liquid silicone-modified superabsorbent polymer, characterized in that, It includes a polyacrylic acid-acrylate crosslinked copolymer and a liquid silicone crosslinked mixture; the liquid silicone crosslinked mixture includes a crosslinking agent, a silica dispersion, a polyol and water; the amount of silica added in the silica dispersion is 0.03-0.2% of the mass of the polyacrylic acid-acrylate crosslinked copolymer.

2. The liquid silicone-modified superabsorbent polymer according to claim 1, characterized in that, The amount of the liquid silicone crosslinking mixture is 2-5% of the weight of the polyacrylic acid-acrylate crosslinking copolymer.

3. The liquid silica-modified superabsorbent polymer according to claim 1, characterized in that, The particle size range of the polyacrylic acid-acrylate crosslinked copolymer is 150-850 μm.

4. The liquid silicone-modified superabsorbent polymer according to claim 1, characterized in that, By weight, it includes 1-3 parts crosslinking agent, 0.63-4.2 parts silica dispersion, 3-8 parts polyol, and 8-15 parts water.

5. The liquid silicone-modified superabsorbent polymer according to claim 1, characterized in that, The crosslinking agent includes ethylene glycol diglycidyl ether.

6. The liquid silicone-modified superabsorbent polymer according to claim 1, characterized in that, The polyol includes at least one of propylene glycol or butanediol.

7. The liquid silicone-modified superabsorbent polymer according to claim 1, characterized in that, The silica dispersion contains 25-45 wt% silica.

8. The liquid silicone-modified superabsorbent polymer according to claim 7, characterized in that, The silica dispersion is of at least one type, Levasil CA330 H or Levasil CA425 H.

9. A method for preparing liquid silicone-modified superabsorbent polymer according to any one of claims 1-8, characterized in that, The process includes the following steps: mixing polyacrylic acid-acrylate crosslinked copolymer and liquid silicone crosslinked mixture, and treating at 120-130℃ for 30-40 minutes to obtain liquid silicone modified superabsorbent polymer.

10. The application of the liquid silicone-modified superabsorbent polymer according to any one of claims 1-8, characterized in that, It is used in agricultural water retention, industrial dehydration, emergency treatment and medical care.

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