Preparation method for polysaccharide spherical gel resin

Abstract

The present invention relates to the technical field of compositions of macromolecular compounds. Disclosed is a preparation method for a polysaccharide spherical gel resin. The preparation method comprises: 1) adding a polysaccharide, a solvent, and an auxiliary agent into a batching kettle on the basis of certain proportions, heating to 85-95°C, and stirring until the mixture is clarified, so as to obtain a polysaccharide mixed solution; 2) conveying the polysaccharide mixed solution to a drip tray, and keeping the temperature of the drip tray at 60-90°C; 3) using a droplet forming device to enable the polysaccharide mixed solution to form spherical droplets, and enabling the spherical droplets to enter a forming tower, and curing and forming to form polysaccharide spherical gel; 4) oily and spherical substance separation; 5) primary cleaning; 6) primary screening; 7) secondary crosslinking; and 8) secondary cleaning, so as to obtain a final product. According to the preparation method for the polysaccharide spherical gel resin provided by the present invention, the prepared polysaccharide spherical gel resin has the advantages of good sphericity, high strength, high yield, good appearance and the like.

Description

A preparation method of polysaccharide spherical gel resin Technical Field

[0001] The invention belongs to the technical field of polymer compositions, and in particular relates to a method for preparing a polysaccharide spherical gel resin. Background Art

[0002] A gel is a specialized dispersion system in which colloidal particles or molecules interconnect under certain conditions, forming a spatial network structure. The interstices within this structure are filled with a dispersion medium. Gels can be classified in many ways, generally based on their source, medium, molecular composition, and the crosslinking method that forms the three-dimensional network structure. Depending on their source, gels can be categorized as natural gels and synthetic gels. Most natural gels are hydrogels formed by carbohydrate or protein derivatives (such as agar, starch, collagen, and gelatin) and a solvent, water. Depending on the medium that binds the network structure, gels can be classified as organogels, hydrogels, aerogels, or xerogels. Based on their molecular composition, gels can be categorized as small-molecule gels and macromolecular gels. Based on their crosslinking method, gels can be divided into chemical gels and supramolecular gels. Chemical gels are formed through strong chemical bonds, making the entire network structure insoluble and thermally inert. Therefore, chemical gels are generally irreversible, their structure expanding or contracting only under certain conditions (such as the addition or removal of solvent).

[0003] Traditional polymer gels are generally made by polymerizing water-soluble monomers such as acrylic acid and its salts, polyvinyl alcohol, and acrylamide. These synthetic gels have disadvantages such as being environmentally polluting and non-biodegradable.

[0004] Natural polysaccharides have been widely used in the food industry. They are made from gums or polysaccharides extracted from plants or biological fermentation, and the products are prepared by physical cross-linking (hydrogen bonds or ionic bonds). Agar is a natural high-molecular polysaccharide extracted from red algae. Agarose can be obtained by removing the agar pectin part of agar containing sulfate (salt), glucuronic acid and pyruvaldehyde. Although both agar and agarose can form gels, compared to agar, agarose is a neutral substance with no charge and will not affect the solute molecules. Therefore, researchers mainly use agarose as a crystallization medium. Agarose gel medium is mainly used for the crystallization of inorganic materials, proteins and amino acids.

[0005] Polymer gels are primarily formed by chemical crosslinking (chemical bonds) or physical crosslinking (hydrogen bonds) of macromolecules (agar, gelatin, etc.) or polymers (polyesters, polyamides, etc.). When polymer gels are formed through strong chemical crosslinking, they are irreversible; when polymer gels are formed through physical crosslinking, they are thermally reversible.

[0006] Chinese invention patent CN102389755B discloses a method for preparing agar gel microspheres, which uses agar as raw material, and obtains agar gel microspheres with a regular spherical shape, uniform particle size, and controllable size within the range of 1 to 900 μm by preparing oil phase and aqueous phase, dispersing and emulsifying, cooling and solidifying, cross-linking, and ligand modification processes with an agar content of 4 to 20 wt%. The method prepares agar gel microspheres by a method of reversed-phase suspension dispersion polymerization, and the obtained gel microspheres have a small particle size (less than 1 mm). And because it is suspension dispersion polymerization, the obtained particle size distribution will be distributed in a certain manner and have polydispersity.

[0007] U.S. Patent No. 6,602,990 B1 discloses a method for preparing porous cross-linked polysaccharide gels. This method utilizes the reaction of hydroxyl groups of the polysaccharide with the active sites of a cross-linking agent to cross-link the gel, forming a polysaccharide gel. The resulting cross-linked polysaccharide gel can be further cross-linked one or more times using conventional methods. This method can be used to produce highly rigid gel particles with a small particle size (approximately 10 μm).

[0008] U.S. Patent No. 50332395A discloses a method for preparing a cross-linked biocompatible polysaccharide gel composition. In the presence of a multifunctional cross-linking agent, a polysaccharide solution is chemically cross-linked to generate a viscoelastic gel. The prepared gel is an amorphous viscoelastic gel, which is mainly used in the field of medical devices.

[0009] The common feature of the existing technical methods is that they use active points on polysaccharide solutions for chemical cross-linking to prepare gels with small particle size and uneven particle distribution or amorphous gels, but cannot prepare large-sized (>4mm) polysaccharide spherical gels with uniform particle size.

[0010] Wang et al. (J. Am. Chem. Soc. 2000, 122, 10, 2399-2400) observed using atomic force microscopy (AFM) that the spaces between molecularly stacked fibers were filled with approximately 30% n-octanol, demonstrating the interaction between solvent molecules and gelators. Since solvent parameters represent the solvent's solvating capacity, they can be used to describe the influence of solvents on the properties of supramolecular gels. This result suggests that dipole interactions and hydrogen bonding between the solvent and gelator are the primary factors affecting gel stability.

[0011] Zhao Chengxiao et al. (Acta Phys. Chim. Sin. 2014, 30(12), 2197-2209) studied the relationship between supramolecular gel properties and solvent parameters, revealing the law of how solvents affect gel properties. Using solvent parameters to study gel properties is a new research method. In the same series of gels (gels formed by the same gel factor gelated in different solvents), there is a linear or exponential relationship between gel properties and solubility parameters. These relationships reflect the influence of changes in the solvent-gel factor interaction on gel properties. Generally speaking, the hydrogen bonding ability of the solvent has a more significant effect on the properties of hydrogen-bonded supramolecular gels than other intermolecular forces: the stronger the hydrogen bonding ability of the solvent, the easier it is to form hydrogen bonds with the gel factor, and the worse the stability of the gel.

[0012] The gel-forming ability and solubility of agarose depend on the basic repeating unit, a long chain of alternating 1,3-linked β-D-galactose and 1,4-linked 3,6-endo-L-galactose, and its relative hydrophobicity, substituted with hydrophobic (methoxy) and polar (sulfate, pyruvate) groups. Each agarose chain contains approximately 800 galactose molecules. Agarose polymer chains form helical fibers that aggregate into superhelical structures with a radius of 20-30 nanometers (nm). The helical fibers are quasi-rigid and have a wide range of lengths, depending on the agarose concentration. When solidified, the fibers form a three-dimensional grid of channels with diameters ranging from 50 nm to >200 nm, depending on the agarose concentration used. The 3-D gel structure is held together by hydrogen bonds and can be disrupted by heating the gel back to the liquid state.

[0013] Therefore, by adjusting the solubility of agarose in solvents, the gel-forming ability of agarose in the solvent can be altered. By regulating the hydrogen bonding interactions between the gel and the solvent, high-strength polysaccharide gels can be prepared. Because the three-dimensional structure of the polysaccharide gel is cross-linked via hydrogen bonds, a reversible physical crosslink, irreversible deformation can occur over time and under pressure, affecting product performance. Therefore, the preparation of high-strength, structurally stable polysaccharide gels through secondary chemical crosslinking is of great significance.

[0014] Summary of the Invention

[0015] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing a polysaccharide spherical gel resin. The prepared polysaccharide spherical gel resin has the advantages of large size, good sphericity, uniform particle size, high strength, and high yield.

[0016] The technical solution adopted by the present invention to solve the technical problem is: a method for preparing a polysaccharide spherical gel resin, the preparation method mainly comprising the following steps:

[0017] 1) Add polysaccharide, solvent and auxiliary agent in a certain proportion into a batching kettle, heat to 85-95°C, and stir until clear to obtain a polysaccharide mixed solution;

[0018] 2) transferring the polysaccharide mixture dissolved in step 1) to a drip tray, wherein the drip tray is kept at 60-90° C.;

[0019] 3) Using a droplet former on the drip tray, the polysaccharide mixture is formed into spherical droplets, which are then introduced into a forming tower; the polysaccharide mixture is solidified and formed in the forming tower; and polysaccharide spherical gels of different particle sizes are prepared by adjusting the feed volume of the droplets; the particle size is 4 to 15 mm. The droplet former comprises a needle with a changeable aperture at the bottom, a cavity with an adjustable volume, and a valve at the top. The polysaccharide solution forms droplets on the needle, which drip under the action of gravity and pressure to form spherical droplets.

[0020] 4) separating the polysaccharide spherical gel formed in step 3) into oil balls at the discharge port at the bottom of the forming tower;

[0021] 5) Primary cleaning: subjecting the polysaccharide spherical gel separated from the oil spheres in step 4) to micro-nano bubble cleaning;

[0022] 6) Primary sieving: Sieving according to certain size requirements to obtain polysaccharide spherical gel of target size;

[0023] 7) Secondary crosslinking: adding a crosslinking agent to the polysaccharide spherical gel that has passed the screening in step 6) and stirring for 1 to 4 hours; then adding an alkaline solution and stirring at 20 to 50° C. for 1 to 24 hours;

[0024] 8) Secondary cleaning: The polysaccharide spherical gel after cross-linking in step 7) is cleaned to a pH value of less than 8 to obtain the final product.

[0025] Furthermore, in step 1), the polysaccharide is one or a mixture of agar, agarose, carrageenan, pectin, gelatin, guar gum, chitosan, and sodium alginate, preferably agarose. The amount of the polysaccharide used is 1 to 5 parts by weight.

[0026] Furthermore, in step 1), the solvent is pure water or an aqueous solution; the aqueous solution is a mixture of water and an organic solvent; the organic solvent is one or a mixture of ethylene glycol, propylene glycol, glycerol, butylene glycol, ethanol, propanol, butanol, hexylene glycol, octanediol, cyclohexanol, ethylene glycol monomethyl ether, acetonitrile, acetone, tetrahydrofuran, ethyl acetate, citric acid, tartaric acid, polyethylene glycol, ionic liquid, sucrose, and sorbitol; in the aqueous solution, the volume ratio of water to the organic solvent is 50 / 50 to 100 / 0; and the amount of the solvent is 100 parts by mass.

[0027] The solubility parameter of water can be adjusted by adding organic solvents. Since the solubility parameter represents the solvating power of a solvent, it can be used to describe the influence of the solvent on gel properties. Dipolar interactions and hydrogen bonding between the solvent and the gelator are the primary factors affecting gel stability. Generally speaking, the hydrogen bonding ability of the solvent has a more significant impact on the properties of hydrogen-bonded supramolecular gels than other intermolecular forces: the stronger the hydrogen bonding ability of the solvent, the easier it is to form hydrogen bonds with the gelator, and the less stable the gel.

[0028] Furthermore, the aqueous solution also includes a small amount of salt; the salt is one or a mixture of sodium salt, potassium salt, calcium salt, aluminum salt, and magnesium salt; the amount of the salt is 0.1 to 3 parts by weight. The salt can change the ionic strength of the polysaccharide solution and improve the gel strength.

[0029] Furthermore, in step 1), the auxiliary agents include pH regulators, preservatives, flavors, and pigments.

[0030] Furthermore, in step 3), the molding tower contains an oily medium, which may be silicone oil, epoxy soybean oil, long-chain alkanes, or grease. The molding tower is divided into a molding buffer zone, a molding zone, and a curing zone from top to bottom; the molding buffer zone is controlled at a temperature of 40-50°C; the molding zone is controlled at a temperature of 10-40°C; and the curing zone is controlled at a temperature of 0-10°C.

[0031] As the liquid drips from the droplet former into the forming tower, the impact forces the droplets deform. Directly forming and solidifying them would affect the sphericity of the spherical gel. As the droplets pass through the forming buffer, the temperature difference between the forming buffer and the droplet temperature is small, preventing them from solidifying quickly and maintaining their spherical shape within the oily medium. As they slowly descend into the forming zone, the polysaccharide mixture begins to slowly solidify, resulting in a highly spherical gel. Continuing to descend into the solidification zone, where the temperature is lower and the droplets remain for a period of time (10 to 30 minutes), a high-strength, highly spherical polysaccharide gel is formed.

[0032] The primary cleaning process uses a bubble cleaning device to clean the spherical gel surface using a bubble generator to generate micro-nano bubbles. The oily medium is then recovered through an oil-water separator for reuse. No detergent is required during the cleaning process, reducing wastewater discharge.

[0033] After the first screening is completed, the polysaccharide spherical gel of qualified size is subjected to the next cross-linking process; the unqualified gel is collected, recycled, heated and dissolved, and then subjected to ball dropping again.

[0034] Furthermore, the crosslinking agent used in the secondary crosslinking is a crosslinking agent containing epoxy groups, including ethylene glycol diglycidyl ether, butanediol diglycidyl ether, polyethylene glycol diglycidyl ether, pentaerythritol tetraglycidyl ether, diethylene glycol diglycidyl ether, and epichlorohydrin; the amount of the crosslinking agent is 0.1 to 3 parts by mass.

[0035] Furthermore, the cross-linking agent is added to the polysaccharide mixture before dripping or added to the polysaccharide spherical gel after sieving.

[0036] Furthermore, in step 7), the alkaline solution is an aqueous solution of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate or potassium phosphate, with a pH value of 10 to 14. The alkaline solution can catalyze the cross-linking reaction between epoxy groups and active groups such as hydroxyl groups and amino groups on the polysaccharide.

[0037] The secondary cleaning process utilizes a rotating drum, which, on the one hand, increases the contact area and improves cleaning efficiency; on the other hand, the rotation of the drum further rounds the polysaccharide spherical gel, improving its sphericity, reducing deformation caused by extrusion during the molding process, and improving the yield rate. The cleaning solution used in the secondary cleaning process is water or an acidic aqueous solution.

[0038] The polysaccharide spherical gel can be used in the fields of water marbles, toys, aromatherapy balls, daily necessities, water retaining agents, medical equipment and the like.

[0039] The beneficial effects of the present invention are as follows: compared with the prior art, the preparation method of the polysaccharide spherical gel resin provided by the present invention has the following advantages:

[0040] 1) Using a water-organic solvent mixture as the polysaccharide solvent for gel formation. By adjusting the solubility parameter of the solution, the hydrogen bonding interaction between the polysaccharide and the solution is changed, thereby improving the strength of the polysaccharide gel.

[0041] 2) Secondary cross-linking uses surface cross-linking to form a core-shell structure. The added cross-linking agent penetrates into the uncross-linked polysaccharide spherical gel, and the cross-linking agent forms a certain concentration gradient in the spherical gel, with a high surface concentration and a lower concentration toward the interior. Under the catalytic action of the alkaline solution, a cross-linking reaction occurs. The surface cross-linking degree is high and the internal cross-linking degree is low, forming a core-shell structured spherical gel with a high-strength shell. The polysaccharide spherical gel prepared after secondary cross-linking has high strength, is not prone to irreversible deformation, and has elasticity and toughness.

[0042] 3) A molding process with dropwise addition and multi-stage temperature control is used. This ensures sphericity and improves gel strength. When the liquid drips from the droplet former into the molding tower, the droplets will deform due to a certain impact force. If they are directly molded and solidified, the sphericity of the spherical gel will be affected. When the droplets pass through the molding buffer, the temperature difference between the buffer and the droplet is small. The droplets do not have time to solidify and will remain spherical in the oily medium. They will slowly descend to the molding zone and slowly solidify, resulting in high sphericity. They will continue to descend to the solidification zone, where the temperature is low and stay for a period of time (10 to 30 minutes) to form a polysaccharide spherical gel with high strength and good sphericity.

[0043] 4) Using micro-nanobubbles to clean polysaccharide gels containing oily media eliminates the need for detergents, using only water. This not only recovers the oily media but also reduces wastewater discharge. Using a rotating drum for cleaning increases contact area and cleaning efficiency. Furthermore, the rotation further rounds the spherical polysaccharide gels, improving their sphericity and minimizing deformation caused by extrusion during the molding process, thereby increasing yield. DETAILED DESCRIPTION

[0044] The present invention will be further described below by way of specific examples, which are only intended to illustrate the present invention and are not intended to limit the scope of the present invention.

[0045] Test method:

[0046] 1) Gel strength

[0047] The gel strength of gel resin is tested using a universal testing machine. Spherical gel particles are placed directly under a dedicated gel strength probe. The probe squeezes the particles until they break. The force required to break the particles is recorded and defined as the gel strength of the spherical water-absorbent resin particles.

[0048] 2) Particle size

[0049] Ten polysaccharide spherical gels were randomly selected, and the gel size was measured using a vernier caliper to obtain the average value.

[0050] 3) Uniformity

[0051] After screening, the weight ratio of particles within the target particle size range (e.g., 7.0-8.0 mm) to the total product particles.

[0052] Example 1

[0053] Add 2g agarose, 90g water, 10g propylene glycol, and a small amount of preservative to a mixing kettle, heat to 90°C, and stir until clear to obtain a polysaccharide mixture. Transfer the dissolved polysaccharide mixture to a drip tray, which is kept at 60-70°C. Use a droplet former to form the polysaccharide mixture into spherical droplets, which are then added to a forming tower. The buffer zone in the forming tower is controlled at 40-50°C; the forming zone at 20-30°C; and the solidification zone at 0-10°C. Oil globules are separated at the bottom outlet of the forming tower. A primary cleaning process: The polysaccharide spherical gel is cleaned and screened.

[0054] Secondary crosslinking: Add 1g of butanediol diglycidyl ether to the screened polysaccharide spherical gel and stir for 4 hours. Add 100g of 0.2% sodium hydroxide solution and stir at 40°C for 4 hours. Filter. Wash the crosslinked polysaccharide spherical gel using a rotary drum until the pH is <8 to obtain the final product. Add 0.5% phenoxyethanol as a preservative.

[0055] The preparation methods used in Examples 2 to 8 are the same as those in Example 1, except that different ratios of raw materials are used. The specific amounts are shown in Table 1 below.

[0056] Table 1. Ingredients in Examples 2 to 8.

[0057] Example 9

[0058] Add 2.5g agarose, 100g water, and 1g butanediol diglycidyl ether to a mixing kettle, heat to 90°C, and stir until clear to obtain a polysaccharide mixture. Transfer the dissolved polysaccharide mixture to a drip tray, which is kept at 60-70°C. Adjust the discharge volume of the liquid former to the target particle size of 6.0-6.8mm, use a droplet former to form the polysaccharide mixture into spherical droplets, and add them to the forming tower. The temperature of the buffer zone in the forming tower is controlled at 40-50°C; the temperature of the forming zone is controlled at 20-30°C; and the temperature of the solidification zone is controlled at 0-10°C. Oil globules are separated at the bottom discharge port of the forming tower. Primary cleaning process: The polysaccharide spherical gel is cleaned and sieved.

[0059] Secondary crosslinking: Add 100g of 0.2% sodium hydroxide solution and stir at 40°C for 24 hours. Filter. Wash the crosslinked polysaccharide spherical gel with water washing solution until the pH is less than 8 to obtain the final product.

[0060] Comparative Example 1

[0061] Add 3g agarose, 100g water, and a small amount of preservative to a batching kettle. Heat to 90°C and stir until clear to obtain a polysaccharide mixture. Transfer the dissolved polysaccharide mixture to a drip tray, which is kept at 60-70°C. Use a droplet former to form spherical droplets, which are then added to a forming tower. The temperature in the forming tower is controlled at 0-10°C. Oil globules are separated at the bottom outlet of the forming tower. Rotary cleaning process: The polysaccharide spherical gel undergoes rotary cleaning and screening.

[0062] Comparative Example 2

[0063] Add 3g agarose, 60g water, 40g propylene glycol, and a small amount of preservative to a mixing kettle, heat to 90°C, and stir until clear to obtain a polysaccharide mixture. Transfer the dissolved polysaccharide mixture to a drip tray, which is kept at 60-70°C. Use a droplet former to form the polysaccharide mixture into spherical droplets, which are then added to a forming tower. The temperature of the buffer zone in the forming tower is controlled at 40-50°C; the temperature of the forming zone is controlled at 20-30°C; and the temperature of the solidification zone is controlled at 0-10°C. Oil globules are separated at the bottom outlet of the forming tower. Rotary cleaning process: The polysaccharide spherical gel is rotary cleaned and screened.

[0064] The polysaccharide spherical gels obtained in Examples 1-9 and Comparative Examples 1-2 were subjected to strength tests before and after secondary crosslinking, and the test results are shown in Table 2. In addition, the appearance of each polysaccharide spherical gel was observed after standing for one month, and the results are also shown in Table 2.

[0065] The above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. Ordinary technicians in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention. The scope of patent protection of the present invention should be defined by the claims.

Claims

1. A method for preparing a polysaccharide spherical gel resin, characterized in that: The preparation method mainly comprises the following steps: 1) Add polysaccharide, solvent and auxiliary agent into a batching kettle according to a certain proportion, heat to 85-95°C, stir until clear, and obtain a polysaccharide mixed solution; 2) transferring the polysaccharide mixture dissolved in step 1) to a drip tray, wherein the drip tray is kept at 60-90° C.; 3) using the droplet former on the drip tray to form spherical droplets of the polysaccharide mixture into a forming tower; the polysaccharide mixture is solidified and formed in the forming tower; and polysaccharide spherical gels of different particle sizes are prepared by adjusting the feeding volume of the droplets; the particle size is 4 to 15 mm; 4) separating the polysaccharide spherical gel formed in step 3) into oil globules at the discharge port at the bottom of the forming tower; 5) primary cleaning: subjecting the polysaccharide spherical gel separated from the oil spheres in step 4) to micro-nano bubble cleaning; 6) Primary sieving: sieving according to certain size requirements to obtain polysaccharide spherical gel of target size; 7) Secondary crosslinking: adding a crosslinking agent to the polysaccharide spherical gel that has passed the screening in step 6), stirring for 1 to 4 hours; then adding an alkaline solution, stirring at 20 to 50° C. for 1 to 24 hours; 8) Secondary cleaning: The cross-linked polysaccharide spherical gel in step 7) is cleaned to a pH value of less than 8 to obtain a final product.

2. The method for preparing a polysaccharide spherical gel resin according to claim 1, characterized in that: In step 1), the polysaccharide is one or a mixture of agar, agarose, carrageenan, pectin, gelatin, guar gum, chitosan, and sodium alginate; and the amount of the polysaccharide is 1 to 5 parts by weight.

3. The method for preparing a polysaccharide spherical gel resin according to claim 1, characterized in that: In step 1), the solvent is pure water or an aqueous solution; the aqueous solution is a mixture of water and an organic solvent; the organic solvent is a mixture of one or more of ethylene glycol, propylene glycol, glycerol, butylene glycol, ethanol, propanol, butanol, hexylene glycol, octanediol, cyclohexanol, ethylene glycol monomethyl ether, acetonitrile, acetone, tetrahydrofuran, ethyl acetate, citric acid, tartaric acid, polyethylene glycol, ionic liquid, sucrose, and sorbitol; in the aqueous solution, the volume ratio of water to the organic solvent is 50 / 50 to 100 / 0; the amount of the solvent is 100 parts by mass.

4. The method for preparing a polysaccharide spherical gel resin according to claim 3, characterized in that: The aqueous solution includes a small amount of salt; the salt is one or a mixture of sodium salt, potassium salt, calcium salt, aluminum salt and magnesium salt; the amount of the salt is 0.1 to 3 parts by weight.

5. The method for preparing a polysaccharide spherical gel resin according to claim 1, characterized in that: In step 1), the auxiliary agents include pH regulators, preservatives, flavors, and pigments.

6. The method for preparing a polysaccharide spherical gel resin according to claim 1, characterized in that: In step 3), the molding tower contains an oily medium, and the molding tower is divided into a molding buffer zone, a molding zone and a curing zone from top to bottom; the temperature of the molding buffer zone is controlled at 40-50°C; the temperature of the molding zone is controlled at 10-40°C; and the temperature of the curing zone is controlled at 0-10°C.

7. The method for preparing a polysaccharide spherical gel resin according to claim 1, characterized in that: The crosslinking agent used in the secondary crosslinking is a crosslinking agent containing epoxy groups, including ethylene glycol diglycidyl ether, butanediol diglycidyl ether, polyethylene glycol diglycidyl ether, pentaerythritol tetraglycidyl ether, diethylene glycol diglycidyl ether, and epichlorohydrin; the amount of the crosslinking agent used is 0.1 to 3 parts by mass.

8. The method for preparing a polysaccharide spherical gel resin according to claim 1 or 7, characterized in that: The cross-linking agent is added into the polysaccharide mixed solution before dripping or into the polysaccharide spherical gel after sieving.

9. The method for preparing a polysaccharide spherical gel resin according to claim 1, characterized in that: In step 7), the alkaline solution is an aqueous solution of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate or potassium phosphate, and the pH value is 10-14.

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