Rapid-absorption super absorbent resin and preparation method thereof

Abstract

The invention relates to a rapid-absorption super absorbent resin and a preparation method thereof, and relates to the technical field of high polymer materials, the preparation method comprises the following steps: (1) neutralizing a hydrophilic monomer to obtain a partially neutralized hydrophilic monomer; uniformly mixing a partially neutralized hydrophilic monomer, an internal crosslinking agent, an initiator, a pore-forming agent, a surfactant and water to obtain a pre-polymerization solution; (2) adding a dispersing agent into petroleum alkane, and uniformly mixing to obtain an oil phase; adding the pre-polymerized liquid into the oil phase for polymerization reaction to obtain polymer gel; (3) sequentially carrying out heat treatment and post-treatment on the polymer gel to obtain resin with interconnected channels inside; and (4) carrying out surface crosslinking treatment on the resin to obtain the rapid-absorption super absorbent resin. The prepared rapid-absorption super absorbent resin has high absorption capacity and extremely high absorption rate, keeps relatively high gel strength, and can be widely applied to the fields of hygienic products, medical dressings, agricultural water retention and the like.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, particularly to the field of polymer polymerization technology, and especially to a fast-absorbing superabsorbent resin and its preparation method. Background Technology

[0002] Superabsorbent polymer (SAP) is a functional polymer material capable of absorbing and retaining hundreds or even thousands of times its own weight in liquid. It is widely used in sanitary napkins, diapers, agriculture and horticulture, medical dressings, and other fields. While traditional superabsorbent polymers have high absorption capacity, they often suffer from slow absorption rates, especially when faced with large amounts of liquid. They cannot quickly absorb and lock in the liquid, leading to side leakage or backflow, which affects the user experience and product performance.

[0003] Therefore, there is an urgent need for a fast-absorbing superabsorbent resin and its preparation method. Summary of the Invention

[0004] This invention provides a fast-absorbing superabsorbent resin and its preparation method, which produces a fast-absorbing superabsorbent resin with both high absorption capacity and extremely fast absorption rate, while maintaining high gel strength. It can be widely used in hygiene products, medical dressings, agricultural water retention and other fields.

[0005] The present invention provides, in a first aspect, a method for preparing a rapidly absorbent superabsorbent resin, comprising: (1) Neutralize the hydrophilic monomer to obtain a partially neutralized hydrophilic monomer; then mix the partially neutralized hydrophilic monomer, internal crosslinking agent, initiator, pore-forming agent, surfactant and water to obtain a prepolymer solution; (2) The dispersant is added to the petroleum-based alkanes and mixed to obtain an oil phase; the prepolymer liquid is added to the oil phase to carry out a polymerization reaction to obtain a polymer gel; (3) The polymer gel is subjected to heat treatment and post-treatment in sequence to obtain a resin with interconnected channels inside; (4) The resin is subjected to surface crosslinking treatment to obtain the fast-absorbing superabsorbent resin.

[0006] Preferably, in step (1): the hydrophilic monomer is acrylic acid; The internal crosslinking agent is at least one of diallylamine, trimethylolpropane triacrylate, and metal ion crosslinking agents; The initiator is persulfate.

[0007] More preferably, the degree of neutralization of the partially neutralized hydrophilic monomer is 60% to 80%.

[0008] More preferably, the initiator is at least one of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0009] Preferably, in step (1): the HLB value of the surfactant is 4 to 6.

[0010] More preferably, the surfactant is at least one of maleic anhydride-modified polyethylene, maleic anhydride-ethylene copolymer, sucrose fatty acid ester, and sapn series surfactants.

[0011] Preferably, in step (1): The raw materials used to prepare the prepolymer solution are in the following weight proportions: 80-100 parts of the hydrophilic monomer, 0.05-0.15 parts of the internal crosslinking agent, 0.5-2 parts of the initiator, 15-30 parts of the pore-forming agent, 0.5-2.5 parts of the surfactant, and 40-80 parts of deionized water.

[0012] Preferably, the pore-forming agent is prepared by the following steps: S1. 2-Dodecyltrithiocarbonate propionic acid, 2,2-dimethylolpropionic acid and toluene are added to a reactor, and propylene oxide is added under a nitrogen atmosphere to react and obtain the first copolymer; S2. Dissolve the first copolymer, thioketone diacrylate and azobisisobutyronitrile in toluene, and react them after three freeze-vacuum-thaw cycles to obtain the second copolymer. S3. The second copolymer, tert-butyl acrylate and azobisisobutyronitrile are dissolved in toluene and reacted after three freeze-vacuum-thaw cycles to obtain the third copolymer. S4. Dissolve the third copolymer in dichloromethane, then add trifluoroacetic acid to react, and then redissolve, precipitate, filter, and dry to obtain the pore-forming agent.

[0013] More preferably, the reaction in step S1 is carried out at 80°C for 24 hours.

[0014] More preferably, the reaction in step S2 is carried out at 70°C for 12 hours.

[0015] More preferably, the reaction in step S3 is carried out at 70°C for 12 hours.

[0016] Preferably, in S1, the raw materials used to prepare the first copolymer are in the following weight parts: 20-100 parts of 2-dodecyl trithiocarbonate propionic acid, 20-60 parts of 2,2-dimethylolpropionic acid, 10-20 parts of toluene, and 20-60 parts of propylene oxide. In S2, the raw materials used to prepare the second copolymer are in the following weight proportions: 20-100 parts of the first copolymer, 20-60 parts of thioketene diacrylate, 20-30 parts of azobisisobutyronitrile, and 10-20 parts of toluene; In S3, the raw materials used to prepare the third copolymer are in the following weight parts: 20-100 parts of the second copolymer, 20-60 parts of tert-butyl acrylate, 20-30 parts of azobisisobutyronitrile, and 10-20 parts of toluene.

[0017] Preferably, in step (2): The dispersant is maleic anhydride-modified polyethylene or maleic anhydride-ethylene copolymer; The petroleum-based alkanes include isohexadecane, white oil, or n-heptane.

[0018] More preferably, the petroleum-based alkane is at least one of the alkanes having 10 to 16 carbon atoms.

[0019] More preferably, in step (2): the mass ratio of the dispersant to the petroleum-based alkane is (2~15):500.

[0020] More preferably, the mass ratio of the hydrophilic monomer to the petroleum-based alkane is 1:5.

[0021] Preferably, in step (2): The polymerization reaction includes: heating to 40~70°C under an inert atmosphere to initiate the polymerization reaction and reacting for 1~4 hours.

[0022] Preferably, in step (3): the temperature of the heat treatment is 80~120℃ and the time is 0.5~2h.

[0023] Preferably, in step (3): the post-treatment is to wash the heat-treated polymer gel with a solvent.

[0024] More preferably, in step (3): the solvent is methanol or ethanol.

[0025] Preferably, step (4) includes: The resin is mixed with a surface crosslinking agent solution and subjected to surface crosslinking treatment at 150~200℃ for 10~60 min to obtain the fast-absorbing superabsorbent resin.

[0026] More preferably, the mass fraction of the surface crosslinking agent in the surface crosslinking agent solution is 1.5 wt%.

[0027] More preferably, the surface crosslinking agent is a compound that can react with the surface functional groups of the resin.

[0028] More preferably, the surface crosslinking agent is at least one of a polyol compound, an epoxy compound, or a polyvalent metal salt.

[0029] Secondly, the present invention provides a fast-absorbing superabsorbent resin prepared by the preparation method of the first aspect described above, wherein the fast-absorbing superabsorbent resin has a three-dimensional interpenetrating network structure and interconnected microporous channels inside.

[0030] More preferably, the rapid-absorbing superabsorbent resin absorbs no less than 30 g / g of 0.9% physiological saline within 30 seconds.

[0031] Compared with the prior art, the present invention has at least the following beneficial effects: (1) By introducing a pore-forming agent during the preparation process and removing it during post-treatment, this invention forms a rich and interconnected pore structure inside the resin, which greatly shortens the path and time for liquid to penetrate and diffuse into the resin, thereby significantly improving the absorption rate. At the same time, through optimized surface crosslinking technology, the crosslinking density of the resin surface is enhanced while ensuring the rapid absorption channels inside the resin. This allows the resin to quickly form a high-strength gel after rapid liquid absorption, effectively preventing the gel from deforming under pressure and preventing liquid backflow.

[0032] (2) In this invention, under low concentration hydrogen peroxide or weak acid conditions, the thioketal bonds inside the pore-forming agent will break, forming new channels. The water-absorbing resin will polymerize along the channels, forming dynamic pores. Therefore, the pore formation rate can be controlled by controlling the concentration of hydrogen peroxide or the pH value, realizing different structures from surface micropores to through pores, so that the resin can meet different application requirements.

[0033] (3) In this invention, the active characteristics of 2-dodecyl trithiocarbonate propionic acid (RAFT-COOH) polymerization can precisely control the length of each block in the pore-forming agent, thereby enabling the resin to have precise pore size and morphology control capabilities. The pore-forming agent is specifically a polypropylene oxide-polythioketal acrylate-polyacrylic acid triblock copolymer (PPO-PTkDA-PAA), in which the PPO block acts as a hydrophobic core, and its length mainly determines the size of the initial template, which is a key parameter for controlling the final pore size; the PAA block acts as a hydrophilic shell, and its length affects the dispersion and phase separation behavior of the pore-forming agent in the matrix, thereby affecting the uniformity of pore distribution; the PTkDA block acts as a degradation switch, and its length affects the degradation rate and the connectivity of the final pores.

[0034] (4) The fast superabsorbent resin prepared by the present invention is particularly suitable for occasions where high absorption speed is required, such as baby diapers, adult incontinence products, superabsorbent layers of feminine hygiene products, as well as medical dressings and agricultural water-retaining agents that require rapid liquid absorption, and has a wide range of applications. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] This invention provides a method for preparing a rapidly absorbent superabsorbent resin, the method comprising: (1) Neutralize the hydrophilic monomer to obtain a partially neutralized hydrophilic monomer; then mix the partially neutralized hydrophilic monomer, internal crosslinking agent, initiator, pore-forming agent, surfactant and water to obtain a prepolymer solution; (2) Add the dispersant to the petroleum-based alkanes and mix well to obtain the oil phase; then add the prepolymer liquid to the oil phase to carry out the polymerization reaction to obtain the polymer gel; (3) The polymer gel is subjected to heat treatment and post-treatment in sequence to obtain a resin with interconnected channels inside; (4) The resin is subjected to surface cross-linking treatment to obtain a fast-absorbing superabsorbent resin.

[0037] In this embodiment of the invention, by introducing a pore-forming agent during the preparation process and removing it in the post-treatment, a rich, interconnected pore structure is formed inside the resin, greatly shortening the path and time for liquid to penetrate and diffuse into the resin, thereby significantly improving the absorption rate. Simultaneously, through optimized surface crosslinking technology, while ensuring rapid absorption channels inside the resin, the crosslinking density of the resin surface is enhanced, enabling the resin to quickly form a high-strength gel after rapid liquid absorption, effectively preventing gel deformation under pressure and liquid backflow.

[0038] In some preferred embodiments, in step (1): the hydrophilic monomer is acrylic acid; The internal crosslinking agent is at least one of diallylamine, trimethylolpropane triacrylate, and metal ion crosslinking agents; The initiator is persulfate.

[0039] In some preferred embodiments, the degree of neutralization of the partially neutralized hydrophilic monomer is 60% to 80% (e.g., it can be 60%, 65%, 70%, 75% or 80%).

[0040] It should be noted that the partially neutralized acrylic acid is obtained by partially neutralizing acrylic acid with an alkaline compound, which can be selected from one or more of sodium hydroxide, potassium hydroxide, and ammonia water.

[0041] In this invention, the degree of neutralization of the superabsorbent polymer (SAP) is a key parameter determining its performance. This degree of neutralization refers to the extent to which the acrylic monomer is neutralized by an alkali (usually sodium hydroxide or potassium hydroxide) before polymerization. Partially neutralized acrylic acid has a neutralization degree of 60%–80%, meaning that 60%–80% of the carboxyl groups are converted to carboxylates. Experiments have shown that if the degree of neutralization of acrylic acid is below 60%, the prepared superabsorbent polymer network contains a large number of unionized -COOH groups, resulting in poor hydrophilicity, insufficient osmotic pressure driving force, and a significant drop in water absorption. Simultaneously, the resin network swells slowly upon contact with water, making it difficult for water molecules to penetrate, resulting in an extremely slow water absorption rate. Furthermore, the large number of hydrogen bonds leads to excessive cross-linking points, resulting in high network rigidity and poor toughness, making the gel hard and brittle. It may even reduce the salt resistance of the superabsorbent polymer, leaving more unreacted monomers. However, if the degree of neutralization of acrylic acid is higher than 80%, the excessively high ionic strength will weaken the osmotic pressure and may even lead to the anti-polyelectrolyte effect, causing the network to shrink and thus reducing the water absorption. At the same time, although the high salt concentration in the initial stage can quickly absorb water, the total water absorption is low, resulting in insufficient water absorption. Moreover, due to the small number of physical cross-linking points, viscous flow is likely to occur, which reduces the gel strength. In addition, an excessively high degree of neutralization will cause the heat to concentrate in the early stage of the polymerization reaction, which can easily trigger explosive polymerization and lead to uneven product properties.

[0042] In some preferred embodiments, the initiator is at least one of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0043] In some preferred embodiments, in step (1): the HLB value of the surfactant is 4 to 6 (e.g., it can be 4, 4.5, 5, 5.5 or 6).

[0044] In some preferred embodiments, the surfactant is at least one selected from maleic anhydride-modified polyethylene, maleic anhydride-ethylene copolymer, sucrose fatty acid ester, and sapn series surfactants.

[0045] In this embodiment of the invention, the surfactant is a nonionic surfactant, which stabilizes the polymerization system and helps to form a uniform pore structure.

[0046] In some preferred embodiments, in step (1): The raw materials used to prepare the prepolymer solution are in the following weight parts: 80-100 parts of hydrophilic monomer (e.g., 80, 85, 90, 95, or 100 parts), 0.05-0.15 parts of internal crosslinking agent (e.g., 0.05, 0.06, 0.08, 0.1, 0.12, or 0.15 parts), and 0.5-2 parts of initiator (e.g., 0.5, 0.6, 0.8, or 1 part). 1.2, 1.5, 1.8 or 2 parts), 15 to 30 parts of pore-forming agent (e.g., 15, 20, 25 or 30 parts), 0.5 to 2.5 parts of surfactant (e.g., 0.5, 1, 1.5, 2 or 2.5 parts), and 40 to 80 parts of deionized water (e.g., 40, 45, 50, 55, 60, 65, 70, 75 or 80 parts).

[0047] In some preferred embodiments, the pore-forming agent is prepared by the following steps: S1. 2-Dodecyltrithiocarbonate propionic acid, 2,2-dimethylolpropionic acid and toluene are added to a reactor, and propylene oxide is added under a nitrogen atmosphere to react and obtain the first copolymer; S2. Dissolve the first copolymer, thioketene diacrylate and azobisisobutyronitrile in toluene, and react them after three freeze-vacuum-thaw cycles to obtain the second copolymer. S3. The second copolymer, tert-butyl acrylate and azobisisobutyronitrile are dissolved in toluene and reacted after three freezing-vacuuming-thawing cycles to obtain the third copolymer. S4. Dissolve the third copolymer in dichloromethane, then add trifluoroacetic acid to react, and then redissolve, precipitate, filter, and dry to obtain the pore-forming agent.

[0048] It should be noted that 2-dodecyl trithiocarbonate propionic acid is the same as 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, with CAS number 461642-78-4. In step S2, the chemical structural formula of the thioketane diacrylate is CH2=C(CH3)-CO-O-CH2-CH2-S-CH2-C(CH3)2-CH2-S-CH2-CH2-O-CO-C(CH3)=CH2, which can be prepared by oneself or purchased.

[0049] In some preferred embodiments, the reaction in step S1 is carried out at 80°C for 24 hours.

[0050] In some preferred embodiments, the reaction in step S2 is carried out at 70°C for 12 hours.

[0051] In some preferred embodiments, the reaction in step S3 is carried out at 70°C for 12 hours.

[0052] In some preferred embodiments, in S1, the raw materials used to prepare the first copolymer are in the following weight parts: 20-100 parts of 2-dodecyl trithiocarbonate propionic acid, 20-60 parts of 2,2-dimethylolpropionic acid, 10-20 parts of toluene, and 20-60 parts of propylene oxide. In S2, the raw materials used to prepare the second copolymer are in the following weight proportions: 20-100 parts of the first copolymer, 20-60 parts of thioketene diacrylate, 20-30 parts of azobisisobutyronitrile, and 10-20 parts of toluene; In S3, the raw materials used to prepare the third copolymer are in the following weight proportions: 20-100 parts of the second copolymer, 20-60 parts of tert-butyl acrylate, 20-30 parts of azobisisobutyronitrile, and 10-20 parts of toluene.

[0053] For 20 to 100 portions, it refers to any value between 20 and 100 portions, such as 20 portions, 25 portions, 30 portions, 35 portions, 40 portions, 45 portions, 50 portions, 55 portions, 60 portions, 65 portions, 70 portions, 75 portions, 80 portions, 85 portions, 90 portions, 95 portions, 100 portions, etc. The range of 20 to 60 portions refers to any value between 20 and 60 portions, such as 20 portions, 25 portions, 30 portions, 35 portions, 40 portions, 45 portions, 50 portions, 55 portions, 60 portions, etc. For 10 to 20 portions, it refers to any value between 10 and 20 portions, such as 10 portions, 11 portions, 12 portions, 13 portions, 14 portions, 15 portions, 16 portions, 17 portions, 18 portions, 19 portions, 20 portions, etc. The range of 20 to 30 portions refers to any value between 20 and 30 portions, such as 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 portions, etc.

[0054] It should be noted that the pore-forming agent is a polypropylene oxide-polythioketone acrylate-polyacrylic acid triblock copolymer (PPO-PTkDA-PAA), and it is soluble in water.

[0055] In this invention, the first copolymer is PPO-CTA, where PPO represents polypropylene oxide and CTA represents 2-dodecyl trithiocarbonate propionic acid (RAFT-COOH). In step S1, a chain transfer reaction occurs. The amount of RAFT-COOH is the decisive factor controlling the molecular weight of the first block polypropylene oxide, directly determining the chain length of PPO-CTA, and thus affecting the final structure and properties of the entire pore-forming agent molecule. Experiments have shown that, with other components remaining constant, if the amount of RAFT-COOH is less than 20 parts, the PPO block has a longer molecular chain, a larger molecular weight, and stronger hydrophobicity. Therefore, during subsequent self-assembly with hydrophilic blocks, it tends to form larger hydrophobic microdomains, potentially resulting in larger channels in the resin material. However, if the amount of RAFT-COOH is greater than 100 parts, the PPO block has a shorter and longer molecular chain, a smaller molecular weight, weaker hydrophobicity, and forms smaller hydrophobic regions, tending to produce smaller channels. Therefore, by precisely controlling the amount of RAFT-COOH, the preliminary design of the final material pore size can be achieved.

[0056] In this embodiment of the invention, the amount of monomeric thioketal diacrylate (TkDA) (relative to the amount of the first copolymer PPO-CTA) is the core factor controlling the length of the second block PTkDA, directly determining the length and density of the smart switches in the block copolymer, and thus affecting the degradation behavior and pore characteristics of the final pore-forming agent. The second copolymer is PPO-PTkDA-CTA, where PTkDA represents polythioketal diacrylate. Since thioketal bonds break under low concentrations of hydrogen peroxide or weak acid conditions, forming new pores, the amount of TkDA is a key parameter for finely controlling the stimulation response sensitivity of the pore-forming agent and the quality of pore formation. To ensure that the final prepared superabsorbent resin can achieve dynamic pore formation, as well as rapid water absorption and high water absorption capacity, the amount of TkDA and the amount of the first copolymer are limited to the above-mentioned range.

[0057] Specifically, in step S4, the third copolymer (PPO-PTkDA-PtBA, where PtBA represents polytert-butyl acrylate) is dissolved in dichloromethane, cooled in an ice-water bath, and then trifluoroacetic acid is slowly added, with stirring at room temperature (e.g., 25°C) for 4 hours. Most of the trifluoroacetic acid and dichloromethane are removed by rotary evaporation. The remaining product is then redissolved in a small amount of tetrahydrofuran and precipitated in a large amount of diethyl ether to remove trifluoroacetic acid and byproducts. The mixture is then filtered and vacuum dried to constant weight to obtain the final pore-forming agent. The core reaction in step S4 is the removal of the tert-butyl protecting group of the third block polytert-butyl acrylate in the third copolymer under the catalysis of the strong acid trifluoroacetic acid, thereby exposing the target hydrophilic carboxyl group and generating the final product PPO-PTkDA-PAA.

[0058] In some preferred embodiments, in step (2): The dispersant is maleic anhydride-modified polyethylene or maleic anhydride-ethylene copolymer; Petroleum-based alkanes include isohexadecane, white oil, or n-heptane.

[0059] In some more preferred embodiments, the petroleum-based alkane is at least one of the alkane having 10 to 16 carbon atoms (e.g., 10, 11, 12, 13, 14, 15 or 16).

[0060] In this embodiment of the invention, experiments have confirmed that the carbon chain length of petroleum-based alkanes in the oil phase directly affects emulsion stability, particle morphology, and final water absorption performance. If the number of carbon atoms in the petroleum-based alkanes in the oil phase is greater than 16, the viscosity of high-carbon-number alkanes increases sharply, which hinders monomer molecule diffusion, reduces the polymerization reaction rate, and leads to incomplete reaction, uneven crosslinking density distribution, and internal pore structure defects. This results in a slow water absorption rate and reduced water absorption ratio of the final product, as well as rough particle surfaces and a wide particle size distribution. However, if the number of carbon atoms in the petroleum-based alkanes is less than 10, the petroleum-based alkanes have high polarity and high surface tension, leading to an imbalance in the interfacial tension between the oil phase and the aqueous phase monomer droplets. This makes the emulsion system unstable, prone to droplet aggregation, excessively small particle size, and severe agglomeration, resulting in uneven polymerization reaction. The final product has a significantly reduced water absorption ratio, poor particle mechanical strength, and is easily broken.

[0061] In some preferred embodiments, in step (2): the mass ratio of dispersant to petroleum-based alkanes is (2~15):500 (for example, it can be 2:500, 3:500, 5:500, 6:500, 8:500, 10:500, 12:500 or 15:500).

[0062] In some preferred embodiments, the mass ratio of the hydrophilic monomer to the petroleum-based alkane is 1:5.

[0063] In some preferred embodiments, in step (2): The polymerization reaction includes: heating to 40~70°C (e.g., 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C) under an inert atmosphere, initiating the polymerization reaction and reacting for 1~4 hours (e.g., 1 hour, 2 hours, 3 hours or 4 hours).

[0064] Specifically, the prepolymer solution is used to obtain the polymer gel via reverse suspension polymerization. Specifically, the prepolymer solution is dispersed in an oil phase containing a dispersant under stirring to form a stable suspension. Then, under inert gas protection, the temperature is raised to 40–70°C to initiate the polymerization reaction, which lasts for 1–4 hours. After the polymerization reaction is complete, polymer gel particles or gel blocks containing a pore-forming agent are obtained.

[0065] In this embodiment of the invention, oxygen, acting as a polymerization inhibitor, can affect the polymerization reaction of rapidly absorbing superabsorbent resins. Therefore, nitrogen gas needs to be introduced to remove oxygen and ensure the normal progress of the polymerization reaction. In this invention, water is used as the reaction medium for the polymerization reaction, which is not only low-cost but also eliminates the environmental pollution caused by organic solvents. The preparation process is simple and requires no heating. Moreover, the reaction medium is neutral, making the preparation process environmentally friendly, pollution-free, energy-efficient, and producing non-toxic and non-corrosive products that do not generate secondary pollution, aligning with the development direction of green and environmentally friendly chemical additives.

[0066] In some preferred embodiments, in step (3): the heat treatment temperature is 80~120℃ (for example, it can be 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃ or 120℃), and the time is 0.5~2h (for example, it can be 0.5h, 1h, 1.5h or 2h).

[0067] In some preferred embodiments, in step (3): the post-treatment is to wash the heat-treated polymer gel with a solvent.

[0068] In some more preferred embodiments, in step (3): the solvent is methanol or ethanol.

[0069] In this embodiment of the invention, step (3) first involves granulating or crushing the polymer gel to obtain gel particles. Then, the gel particles are heat-treated at 80-120°C for 0.5-2 hours to further complete the reaction and initially fix the structure. The heat-treated gel particles are then washed with a solvent to dissolve and remove the pore-forming agent, thereby forming a large number of interconnected micron- and submicron-sized pores within the resin. This step is crucial for forming rapid absorption channels.

[0070] In some preferred embodiments, step (4) includes: The resin is mixed with a surface crosslinking agent solution and subjected to surface crosslinking treatment at 150~200℃ (e.g., 150℃, 160℃, 170℃, 180℃, 190℃ or 200℃) for 10~60 min (e.g., 10 min, 20 min, 30 min, 40 min, 50 min or 60 min) to obtain a fast-absorbing superabsorbent resin.

[0071] In some preferred embodiments, the mass fraction of the surface crosslinking agent in the surface crosslinking agent solution is 1.5 wt%.

[0072] In some preferred embodiments, the surface crosslinking agent is a compound that can react with the surface functional groups of the resin.

[0073] In some preferred embodiments, the surface crosslinking agent is at least one of a polyol compound, an epoxy compound, or a polyvalent metal salt.

[0074] In this embodiment of the invention, surface crosslinking can form a dense crosslinking network on the outer layer of resin particles, improving gel strength, while the internal pore structure is preserved, thereby achieving the effect of surface water locking and internal rapid absorption.

[0075] It should be noted that the fast-absorbing superabsorbent resin obtained in step (4) also includes: finally drying the fast-absorbing superabsorbent resin to make its moisture content less than 10%, and then crushing and sieving it appropriately to obtain a fast-absorbing superabsorbent resin product with the required particle size range (e.g., 150~850μm).

[0076] It should be noted that at least one refers to a mixture of any one or more of them in any proportion.

[0077] The present invention also provides a fast-absorbing superabsorbent resin, which is prepared by any of the above-described preparation methods. The fast-absorbing superabsorbent resin has a three-dimensional interpenetrating network structure and interconnected microporous channels inside.

[0078] In some preferred embodiments, the rapid-absorbing superabsorbent resin absorbs no less than 30 g / g of 0.9% physiological saline at 30s and no less than 40 g / g at saturation at 60min.

[0079] Unless otherwise specified, the raw materials used in this invention can be commercially available products or synthesized by existing methods; In this invention, the use of "and / or" between multiple technical features indicates that these technical features are connected by an "and / or" relationship, meaning that it can be any one of these technical features, or any combination of two or more of these technical features.

[0080] The present invention will be further described below by way of examples, but the scope of protection of the present invention is not limited to these embodiments.

[0081] In the following examples and comparative examples, the pore-forming agents were prepared by the following method. During the preparation of the pore-forming agents, the amount of each component is expressed in parts by weight. Preparation of the pore-forming agent: S1. Add 40 parts of 2-dodecyl trithiocarbonate propionic acid, 40 parts of 2,2-dimethylolpropionic acid and 20 parts of toluene to the reactor, and add 40 parts of propylene oxide through a syringe under a nitrogen atmosphere. React at 80°C for 24 h. After the reaction is completed, dissolve the reaction solution in a small amount of tetrahydrofuran, then precipitate it in a large amount of ice-cold diethyl ether, filter, and vacuum dry to obtain the first copolymer PPO-CTA. S2. Dissolve 40 parts of the first copolymer, 40 parts of thioketene diacrylate and 20 parts of azobisisobutyronitrile in 20 parts of toluene, and perform three freeze-vacuum-thaw cycles to completely remove oxygen. After reacting at 70°C for 12 hours, precipitate in ice-cold ether to obtain the second copolymer PPO-PTkDA-CTA. S3. Dissolve 40 parts of the second copolymer, 40 parts of tert-butyl acrylate and 20 parts of azobisisobutyronitrile in 20 parts of toluene, and perform three freeze-vacuum-thaw cycles to completely remove oxygen. After reacting at 70°C for 12 hours, precipitate in ice-cold ether to obtain the third copolymer PPO-PTkDA-PtBA. S4. Dissolve the third copolymer in dichloromethane, cool in an ice-water bath, and then slowly add trifluoroacetic acid. Stir at room temperature (e.g., 25°C) for 4 hours. Remove most of the trifluoroacetic acid and dichloromethane by rotary evaporation. Then redissolve the remaining product in a small amount of tetrahydrofuran and precipitate in a large amount of diethyl ether to remove trifluoroacetic acid and byproducts. Then filter and vacuum dry to constant weight to obtain the final pore-forming agent.

[0082] Example 1 A method for preparing a rapidly absorbing superabsorbent resin, comprising: (1) Add 100g of acrylic acid to the reactor and neutralize it with 40% sodium hydroxide aqueous solution until the degree of neutralization is 75%. The temperature of the neutralization process is controlled at 20~30℃, and then cooled to 10~15℃. Then, add 0.05g of trimethylolpropane triacrylate (internal crosslinking agent), 0.5g of potassium persulfate (initiator), 20g of PPO-PTkDA-PAA (pore-forming agent), 0.5g of Span-80 (surfactant), and 40g of water to the reactor and mix well to obtain the prepolymer solution; (2) In another reactor equipped with a stirrer, thermometer and nitrogen inlet pipe, 500g of isohexadecane and 2g of maleic anhydride modified polyethylene (dispersant) were added to obtain an oil phase; then the prepolymer liquid from step (1) was slowly added under stirring to form a suspension. Nitrogen was introduced to remove oxygen, the temperature was raised to 55°C and the reaction was carried out for 3 hours; after the reaction was completed, polymer gel particles were obtained by centrifugation. (3) Heat-treat the polymer gel particles at 100°C for 0.5 h, then take them out and wash them three times with a 75% ethanol aqueous solution at room temperature (25°C) to completely remove the pore-forming agent and other substances; then dry the washed polymer gel particles at 80°C to constant weight to obtain resin particles. (4) Mix the resin particles from step (3) with an ethanol / water mixture containing 1.5wt% ethylene glycol diglycidyl ether (surface crosslinking agent) and react at 180℃ for 30 min to perform surface crosslinking. After the reaction is completed, cool, dry, pulverize and sieve to obtain a fast-absorbing superabsorbent resin product A with a size of 150~850μm (moisture content less than 10%).

[0083] Example 2 A method for preparing a rapidly absorbing superabsorbent resin, comprising: (1) Add 100g of acrylic acid to the reactor and neutralize it with 40% sodium hydroxide aqueous solution until the degree of neutralization is 75%. The temperature of the neutralization process is controlled at 20~30℃, and then cooled to 10~15℃. Then, add 0.05g of trimethylolpropane triacrylate (internal crosslinking agent), 0.5g of potassium persulfate (initiator), 25g of PPO-PTkDA-PAA (pore-forming agent), 0.5g of Span-80 (surfactant), and 40g of water to the reactor and mix well to obtain the prepolymer solution; (2) In another reactor equipped with a stirrer, thermometer and nitrogen inlet pipe, 500g of white oil and 2g of maleic anhydride modified polyethylene (dispersant) were added to obtain the oil phase; then the prepolymer liquid from step (1) was slowly added under stirring to form a suspension. Nitrogen was introduced to remove oxygen, the temperature was raised to 55℃, and the reaction was carried out for 3 hours; after the reaction was completed, polymer gel particles were obtained by centrifugation. (3) Heat-treat the polymer gel particles at 100°C for 1 hour, then take them out and wash them three times with a 75% ethanol aqueous solution at room temperature (25°C) to completely remove the pore-forming agent and other substances; then dry the washed polymer gel particles at 80°C to constant weight to obtain resin particles. (4) Mix the resin particles from step (3) with an ethanol / water mixture containing 1.5wt% ethylene glycol diglycidyl ether (surface crosslinking agent) and react at 180℃ for 30 min to perform surface crosslinking. After the reaction is completed, cool, dry, pulverize and sieve to obtain a fast-absorbing superabsorbent resin product B with a size of 150~850μm (moisture content less than 10%).

[0084] Example 3 A method for preparing a rapidly absorbing superabsorbent resin, comprising: (1) Add 80g of acrylic acid to the reactor and neutralize it with 40% sodium hydroxide aqueous solution until the degree of neutralization is 75%. The temperature of the neutralization process is controlled at 20~30℃, and then cooled to 10~15℃. Then, add 0.05g of trimethylolpropane triacrylate (internal crosslinking agent), 0.5g of potassium persulfate (initiator), 15g of PPO-PTkDA-PAA (pore-forming agent), 0.5g of Span-80 (surfactant), and 40g of water to the reactor and mix well to obtain the prepolymer solution; (2) In another reactor equipped with a stirrer, thermometer and nitrogen inlet pipe, 500g of white oil and 2g of maleic anhydride modified polyethylene (dispersant) were added to obtain the oil phase; then the prepolymer liquid from step (1) was slowly added under stirring to form a suspension. Nitrogen was introduced to remove oxygen, the temperature was raised to 55℃, and the reaction was carried out for 3 hours; after the reaction was completed, polymer gel particles were obtained by centrifugation. (3) Heat-treat the polymer gel particles at 100°C for 1 hour, then take them out and wash them three times with a 75% ethanol aqueous solution at room temperature (25°C) to completely remove the pore-forming agent and other substances; then dry the washed polymer gel particles at 80°C to constant weight to obtain resin particles. (4) Mix the resin particles from step (3) with an ethanol / water mixture containing 1.5wt% ethylene glycol diglycidyl ether (surface crosslinking agent) and react at 180℃ for 30 min to perform surface crosslinking. After the reaction is completed, cool, dry, pulverize and sieve to obtain a fast-absorbing superabsorbent resin product C with a size of 150~850μm (moisture content less than 10%).

[0085] Example 4 A method for preparing a rapidly absorbing superabsorbent resin, comprising: (1) Add 100g of acrylic acid to the reactor and neutralize it with 40% sodium hydroxide aqueous solution until the degree of neutralization is 75%. The temperature of the neutralization process is controlled at 20~30℃, and then cooled to 10~15℃. Then, add 0.05g of trimethylolpropane triacrylate (internal crosslinking agent), 0.5g of potassium persulfate (initiator), 15g of PPO-PTkDA-PAA (pore-forming agent), 0.5g of Span-80 (surfactant), and 40g of water to the reactor and mix well to obtain the prepolymer solution; (2) In another reactor equipped with a stirrer, thermometer and nitrogen inlet pipe, 500g of white oil and 5g of maleic anhydride modified polyethylene (dispersant) were added to obtain the oil phase; then the prepolymer liquid from step (1) was slowly added under stirring to form a suspension. Nitrogen was introduced to remove oxygen, the temperature was raised to 55℃, and the reaction was carried out for 3 hours; after the reaction was completed, polymer gel particles were obtained by centrifugation. (3) Heat-treat the polymer gel particles at 100°C for 1 hour, then take them out and wash them three times with a 75% ethanol aqueous solution at room temperature (25°C) to completely remove the pore-forming agent and other substances; then dry the washed polymer gel particles at 80°C to constant weight to obtain resin particles. (4) Mix the resin particles from step (3) with an ethanol / water mixture containing 1.5wt% ethylene glycol diglycidyl ether (surface crosslinking agent) and react at 180℃ for 30 min to perform surface crosslinking. After the reaction is completed, cool, dry, pulverize and sieve to obtain a fast-absorbing superabsorbent resin product D with a size of 150~850μm (moisture content less than 10%).

[0086] Example 5 Example 5 is basically the same as Example 1, except that the amount of pore-forming agent used is different.

[0087] Specifically, step (1): In the reaction vessel, add 100g of acrylic acid, neutralize it with 40% sodium hydroxide aqueous solution to a neutralization degree of 75%, control the temperature of the neutralization process at 20~30℃, and then cool it to 10~15℃; Then, add 0.05g diallylamine (internal crosslinking agent), 0.5g potassium persulfate (initiator), 30g PPO-PTkDA-PAA (pore-forming agent), 0.5g Span-80 (surfactant), and 40g water to the reactor and mix well to obtain the prepolymer solution.

[0088] Example 6 Example 6 is basically the same as Example 1, except that the degree of neutralization of acrylic acid is different.

[0089] Specifically, step (1): In the reaction vessel, add 100g of acrylic acid, neutralize it with 40% sodium hydroxide aqueous solution to a neutralization degree of 60%, control the temperature of the neutralization process at 20~30℃, and then cool it to 10~15℃; Then, add 0.05g diallylamine (internal crosslinking agent), 0.5g potassium persulfate (initiator), 20g PPO-PTkDA-PAA (pore-forming agent), 0.5g Span-80 (surfactant), and 40g water to the reactor and mix well to obtain the prepolymer solution.

[0090] Example 7 Example 7 is basically the same as Example 1, except that the degree of neutralization of acrylic acid is different.

[0091] Specifically, step (1): In the reaction vessel, add 100g of acrylic acid, neutralize it with 40% sodium hydroxide aqueous solution to a neutralization degree of 80%, control the temperature of the neutralization process at 20~30℃, and then cool it to 10~15℃; Then, add 0.05g diallylamine (internal crosslinking agent), 0.5g potassium persulfate (initiator), 20g PPO-PTkDA-PAA (pore-forming agent), 0.5g Span-80 (surfactant), and 40g water to the reactor and mix well to obtain the prepolymer solution.

[0092] Comparative Example 1 Comparative Example 1 is basically the same as Example 1, except that no pore-forming agent was added.

[0093] Specifically, step (1): In the reaction vessel, add 100g of acrylic acid, neutralize it with 40% sodium hydroxide aqueous solution to a neutralization degree of 75%, control the temperature of the neutralization process at 20~30℃, and then cool it to 10~15℃; Then, add 0.05g of trimethylolpropane triacrylate (internal crosslinking agent), 0.5g of potassium persulfate (initiator), 0.5g of Span-80 (surfactant), and 40g of water to the reactor and mix well to obtain the prepolymer solution.

[0094] Comparative Example 2 Comparative Example 2 is basically the same as Example 1, except that no pore-forming agent and surfactant were added.

[0095] Specifically, step (1): In the reaction vessel, add 100g of acrylic acid, neutralize it with 40% sodium hydroxide aqueous solution to a neutralization degree of 75%, control the temperature of the neutralization process at 20~30℃, and then cool it to 10~15℃; Then, add 0.05g of trimethylolpropane triacrylate (internal crosslinking agent), 0.5g of potassium persulfate (initiator), and 40g of water to the reactor and mix well to obtain the prepolymer solution.

[0096] Comparative Example 3 Comparative Example 3 is basically the same as Example 3, except that no pore-forming agent was added and the amount of internal crosslinking agent was 0.2g.

[0097] Specifically, step (1): In the reaction vessel, add 80g of acrylic acid and neutralize it with 40% sodium hydroxide aqueous solution until the degree of neutralization is 75%. The temperature of the neutralization process is controlled at 20~30℃, and then cooled to 10~15℃. Then, add 0.2g of trimethylolpropane triacrylate (internal crosslinking agent), 0.5g of potassium persulfate (initiator), 0.5g of Span-80 (surfactant), and 40g of water to the reactor and mix well to obtain the prepolymer solution.

[0098] Comparative Example 4 Comparative Example 4 is basically the same as Example 3, except that no pore-forming agent was added and the degree of neutralization of acrylic acid is different.

[0099] Specifically, step (1): In the reaction vessel, add 80g of acrylic acid and neutralize it with 40% sodium hydroxide aqueous solution until the degree of neutralization is 60%. The temperature of the neutralization process is controlled at 20~30℃, and then cooled to 10~15℃. Then, add 0.05g of trimethylolpropane triacrylate (internal crosslinking agent), 0.5g of potassium persulfate (initiator), 0.5g of Span-80 (surfactant), and 40g of water to the reactor and mix well to obtain the prepolymer solution.

[0100] Comparative Example 5 Comparative Example 5 is basically the same as Example 3, except that: no pore-forming agent and surfactant were added in step (1), and the amounts of internal crosslinking agent and initiator were different; no dispersant was added in step (2).

[0101] Specifically, step (1): In the reaction vessel, add 80g of acrylic acid and neutralize it with 40% sodium hydroxide aqueous solution until the degree of neutralization is 75%. The temperature of the neutralization process is controlled at 20~30℃, and then cooled to 10~15℃. Then, add 0.2g of trimethylolpropane triacrylate (internal crosslinking agent), 1.0g of potassium persulfate (initiator), and 40g of water to the reactor and mix well to obtain the prepolymer solution; (2) In another reactor equipped with a stirrer, thermometer and nitrogen inlet pipe, 500g of white oil was added to obtain the oil phase; then the prepolymer liquid from step (1) was slowly added under stirring to form a suspension. Nitrogen was introduced to remove oxygen, the temperature was raised to 55℃ and the reaction was carried out for 3h; after the reaction was completed, polymer gel particles were obtained by centrifugation.

[0102] Comparative Example 6 A method for preparing a water-absorbing resin, comprising: (1) Add 100g of acrylic acid to the reactor and neutralize it with 40% sodium hydroxide aqueous solution until the degree of neutralization is 75%. The temperature of the neutralization process is controlled at 20~30℃, and then cooled to 10~15℃. Then, add 0.05g of trimethylolpropane triacrylate (internal crosslinking agent), 0.5g of potassium persulfate (initiator), 20g of sodium bicarbonate (pore-forming agent), 0.5g of Span-80 (surfactant), and 40g of water to the reactor and mix well to obtain the prepolymer solution; (2) Pour the prepolymer liquid into a polytetrafluoroethylene pan, purge with nitrogen, and let it stand in a water bath at 60°C for 2 hours to polymerize, and then crush it with a granulator to obtain polymer gel particles with a particle size of 1~5mm. (3) Heat-treat the polymer gel particles at 110°C for 1.5 h, then take them out and wash them with a 75% ethanol aqueous solution at room temperature (25°C) until no chloride ions are detected in the washing solution to remove sodium chloride pore-forming agent; then dry the washed polymer gel particles at 80°C to constant weight to obtain resin particles. (4) Mix the resin particles from step (3) with an ethanol / water mixture containing 1.5wt% ethylene glycol diglycidyl ether (surface crosslinking agent) and react at 180℃ for 30 min to perform surface crosslinking. After the reaction is completed, cool, dry, pulverize and sieve to obtain a fast-absorbing superabsorbent resin product with a size of 150~850μm (moisture content less than 10%).

[0103] It should be noted that the moisture content of the fast-absorbing superabsorbent resin products prepared in the above embodiments and comparative examples is the same, and is all less than 10%.

[0104] The products prepared in the examples and comparative examples of this invention were subjected to performance tests, and the test data are shown in Table 1. The absorption rate was tested as follows: 0.1000g of product (recorded as W0) was placed in a tea bag, which was then immersed in 0.9% physiological saline solution for 30 seconds. After 30 seconds, the tea bag was removed, suspended to drain until no more water dripped, and then weighed (recorded as W1). The absorption capacity after 30 seconds was calculated as (W1-W0-W2) / W0, where W2 is the weight of the tea bag. Saturated absorption capacity (absorption capacity over 60 minutes, g / g): The method was the same as above, but the soaking time was extended to 60 minutes. Pressure absorption capacity (0.7 psi, 60 minutes, g / g): Tested according to the standard method Q / 0500SNE016-2017.

[0105] Table 1 As shown in Table 1, the fast-absorbing superabsorbent resin product prepared by the present invention has a significantly better absorption rate than the superabsorbent resin product prepared in the comparative example. At the same time, it also maintains excellent saturated absorption capacity and pressure absorption capacity, indicating that the fast-absorbing superabsorbent resin product of the present invention can quickly form a high-strength gel after absorbing liquid, effectively preventing the gel from deforming under pressure and liquid backflow.

[0106] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing a rapidly absorbing superabsorbent resin, characterized by comprising the steps of: The method comprises the following steps: ​ (1) neutralizing a hydrophilic monomer to obtain a partially neutralized hydrophilic monomer; Then, the partially neutralized hydrophilic monomer, an internal crosslinking agent, an initiator, a pore-forming agent, a surfactant and water are uniformly mixed to obtain a prepolymer solution; (2) adding a dispersing agent into petroleum-based alkanes to obtain an oil phase; and adding the prepolymer solution into the oil phase to perform a polymerization reaction to obtain a polymer gel; (3) sequentially performing heat treatment and post-treatment on the polymer gel to obtain a resin with interconnected pores inside; (4) performing surface crosslinking treatment on the resin to obtain the fast-absorbing superabsorbent resin.

2. The production method according to claim 1, characterized by, In step (1): The hydrophilic monomer is acrylic acid; preferably, the neutralization degree of the partially neutralized hydrophilic monomer is 60% to 80%; The internal crosslinking agent is at least one of a diallylamine, a trimethylolpropane triacrylate and a metal ion crosslinking agent; The initiator is a persulfate; preferably, the initiator is at least one of sodium persulfate, potassium persulfate and ammonium persulfate; and / or The HLB value of the surfactant is 4 to 6; preferably, the surfactant is at least one of a maleic anhydride modified polyethylene, a maleic anhydride-ethylene copolymer, a sucrose ester fatty acid ester and a sapn-based surfactant.

3. The preparation method according to claim 1, characterized in that, In step (1): The weight parts of raw materials used for preparing the prepolymer solution are as follows: the hydrophilic monomer 80 to 100 parts, the internal crosslinking agent 0.05 to 0.15 parts, the initiator 0.5 to 2 parts, the pore-forming agent 15 to 30 parts, the surfactant 0.5 to 2.5 parts and deionized water 40 to 80 parts.

4. The method of claim 1, wherein, The pore-forming agent is prepared by the following steps: S1, 2-dodecyltrithiocarbonate propionic acid, 2,2-dimethylol propionic acid and toluene are added into a reactor, and propylene oxide is added in a nitrogen atmosphere to perform a reaction to obtain a first copolymer; preferably, the reaction is performed at 80°C for 24h; S2, the first copolymer, a sulfur ketal dipropylene acid ester and azobisisobutyronitrile are dissolved in toluene, and after three cycles of freezing-vacuumizing- thawing, a reaction is performed to obtain a second copolymer; preferably, the reaction is performed at 70°C for 12h; S3, the second copolymer, t-butyl acrylate and azobisisobutyronitrile are dissolved in toluene, and after three cycles of freezing-vacuumizing-thawing, a reaction is performed to obtain a third copolymer; preferably, the reaction is performed at 70°C for 12h; S4, the third copolymer is dissolved in dichloromethane, then trifluoroacetic acid is added to perform a reaction, and then redissolution, precipitation, filtration and drying are performed to obtain the pore-forming agent.

5. The preparation method according to claim 4, characterized in that: In S1, the weight parts of raw materials used for preparing the first copolymer are as follows: 2-dodecyltrithiocarbonate propionic acid 20 to 100 parts, 2,2-dimethylol propionic acid 20 to 60 parts, toluene 10 to 20 parts and propylene oxide 20 to 60 parts; In S2, the weight parts of raw materials used for preparing the second copolymer are as follows: the first copolymer 20-100 parts, sulfur ketal diacrylate 20-60 parts, azobisisobutyronitrile 20-30 parts, and toluene 10-20 parts; In S3, the weight parts of raw materials used for preparing the third copolymer are as follows: the second copolymer 20-100 parts, t-butyl acrylate 20-60 parts, azobisisobutyronitrile 20-30 parts, and toluene 10-20 parts.

6. The method of claim 1, wherein, In step (2): The dispersant is maleic anhydride modified polyethylene or maleic anhydride-ethylene copolymer; The petroleum-based alkane includes isohexadecane, white oil, or n-heptane; preferably at least one of alkanes with a C atom number of 10-16; Preferably, the mass ratio of the dispersant to the petroleum-based alkane is (2-15):500; More preferably, the mass ratio of the hydrophilic monomer to the petroleum-based alkane is 1:

5.

7. The preparation method according to claim 1, characterized in that, In step (2): The polymerization reaction includes: heating to 40-70°C under an inert atmosphere, initiating the polymerization reaction, and reacting for 1-4 h.

8. The production method according to any one of claims 1 to 7, characterized by, In step (3): The temperature of the heat treatment is 80-120°C, and the time is 0.5-2 h; and / or, The post-treatment is washing the polymer gel after the heat treatment with a solvent; preferably, the solvent is methanol or ethanol.

9. The production method according to any one of claims 1 to 7, characterized by, The step (4) includes: Mixing the resin with a surface crosslinking agent solution and performing surface crosslinking treatment at 150-200°C for 10-60 min to obtain the fast-absorbing superabsorbent resin; preferably, the mass fraction of the surface crosslinking agent in the surface crosslinking agent solution is 1.5 wt%; preferably, the surface crosslinking agent is a compound that can react with the surface functional groups of the resin; more preferably, the surface crosslinking agent is at least one of a polyol compound, an epoxy compound, and a polyvalent metal salt.

10. A fast-absorbing superabsorbent resin prepared by the preparation method of any one of claims 1-9, the fast-absorbing superabsorbent resin having a three-dimensional interpenetrating network structure and interconnected micropore channels in the interior; preferably, the fast-absorbing superabsorbent resin has an absorption amount of not less than 30 g / g for 0.9% physiological saline at 30 s.

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