Preparation method of anticoagulant superabsorbent resin

Abstract

The present application relates to the technical field of resin preparation, and relates to a preparation method of an anticoagulant superabsorbent resin, which comprises the following steps: combining hydrolyzed tannic acid and nanocellulose through an oxidative coupling reaction, loading citric acid to obtain an anticoagulant compound; dissolving acrylic acid, sulfonated lignin, the anticoagulant compound, polylactic acid-diacrylate, azodicarboxamide, nanosilica and a photoinitiator in water to obtain a mixed solution; injecting the mixed solution into a microchannel reactor to perform a polymerization reaction under irradiation of pulsed ultraviolet light, so as to obtain a superabsorbent resin gel; immersing the superabsorbent resin gel in a polylactic acid-diacrylate solution, performing surface crosslinking through ultraviolet light irradiation, drying and grinding, so as to obtain anticoagulant superabsorbent resin particles; and the present application can inhibit platelet aggregation, delay the start of the coagulation cascade reaction, block the activation of coagulation factors, effectively prolong the blood clotting time, and provide a more sufficient liquid absorption window for the superabsorbent resin.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resin preparation, and more particularly, it relates to a preparation method of an anticoagulant superabsorbent resin. BACKGROUND

[0002] Sanitary absorbent products, such as paper diapers and sanitary napkins, play an important role in the fields of infant care, female menstrual care, and incontinence care. Superabsorbent polymers (SAP) are widely used as the core liquid-absorbing material in such products due to their ability to absorb and lock a large amount of liquid. By significantly improving the dryness and comfort of sanitary products, superabsorbent polymers effectively reduce the risk of skin irritation and infection. However, existing superabsorbent polymers face multiple technical challenges when dealing with blood, a complex liquid, especially in products such as sanitary napkins, which require high-efficiency absorption and anticoagulant properties.

[0003] Blood is rich in coagulation factors and platelets, and once it comes into contact with air or foreign surfaces, it will quickly trigger a coagulation cascade, leading to rapid clotting of the blood. This rapid clotting phenomenon poses a significant obstacle to the liquid-absorbing properties of superabsorbent polymers. The clotted blood forms clots on the surface of the resin, blocking the liquid-absorbing channels, making it difficult for the internal resin to contact and absorb deep-layer liquid, thereby reducing the overall liquid-absorbing efficiency and surface dryness. Users may feel uncomfortable due to the surface moisture during use, increasing the risk of skin irritation. In addition, the high viscosity and complex composition of blood (including plasma proteins, red blood cells, etc.) differ greatly from water or urine, further exacerbating the deficiencies of existing SAP in blood absorption.

[0004] To solve the above problems, some improvement schemes are proposed in the existing technology. For example, the patent with publication number CN118459649A discloses an anticoagulant superabsorbent resin and a preparation method thereof. The method prepares propylene-1,2,3-tricarboxylic acid functional monomers through citric acid dehydration and uses them in the synthesis of superabsorbent resin. The carboxylate ions combine with calcium ions in blood to form soluble complexes, blocking the activation process of coagulation factors. However, this technology has a low stability constant of calcium propylene-1,2,3-tricarboxylate, which cannot meet the long-term anticoagulation requirements, especially in a dynamic blood environment, the anticoagulant performance stability is insufficient. It uses a single surface crosslinking agent for secondary crosslinking, which cannot form a gradient crosslinking network, resulting in unsatisfactory dynamic coagulation index and compression resistance of the resin, limiting the liquid-absorbing efficiency and dryness. This method does not optimize other coagulation mechanisms such as platelet aggregation, and relies only on the single path of calcium ion chelation, limiting the comprehensiveness of the anticoagulant effect.

[0005] Therefore, developing a preparation method of a superabsorbent resin capable of effectively inhibiting platelet aggregation, delaying the coagulation cascade reaction, and blocking the activation of coagulation factors, while having high liquid absorption performance, becomes a technical requirement to be solved. SUMMARY

[0006] To this end, the purpose of the present application is to provide a preparation method of an anticoagulant superabsorbent resin, which can inhibit platelet aggregation, delay the initiation of the coagulation cascade reaction, and block the activation of coagulation factors, effectively prolonging the clotting time of blood and providing a more sufficient liquid absorption window for the superabsorbent resin.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0008] A preparation method of an anticoagulant superabsorbent resin, comprising the following steps:

[0009] S1, preparing an anticoagulant compound: combining hydrolyzed tannic acid and nanocellulose through oxidative coupling reaction, and then loading citric acid to obtain an anticoagulant compound;

[0010] S2, preparing a mixed solution: dissolving acrylic acid, sulfonated lignin, the anticoagulant compound, polylactic acid-diacrylate, azobisformamide, nanosilica, and a photoinitiator in water, and mixing uniformly to obtain a mixed solution;

[0011] S3, UV micro-reaction polymerization: injecting the mixed solution into a micro-channel reactor, and performing polymerization reaction under pulse ultraviolet light irradiation to obtain a superabsorbent resin gel;

[0012] S4, surface strengthening: immersing the superabsorbent resin gel in a polylactic acid-diacrylate solution, and performing surface crosslinking through ultraviolet light irradiation, and then drying and grinding to obtain anticoagulant superabsorbent resin particles.

[0013] The present application is further provided that: the S1 comprises the following steps:

[0014] S11, mixing hydrolyzed tannic acid and nanocellulose at a mass ratio of (2-3):(1-2), adding FeCl3·6H2O and H2O2 solution, stirring and reacting at pH 3-4 and a temperature of 50-55°C for 2-3 hours to perform oxidative coupling to form a graft product;

[0015] S12, adding citric acid to the graft product at a mass ratio of (1-2):3, adsorbing at a temperature of 50°C for 2 hours under ultrasonic assistance, and then drying at 60°C for 3 hours after centrifugation to obtain an anticoagulant compound.

[0016] The present application is further provided that: in the step S11,

[0017] The mass ratio of the FeCl3·6H2O to the hydrolyzed tannic acid is 1:(10-15); the concentration of the H2O2 is 10-20 wt%, and nitrogen is passed during the reaction,

[0018] The Zeta potential of the citric acid loaded compound is -35 to -25 mV, and the specific surface area is 50-80 m² / g.

[0019] The application further provides that the step S2 comprises:

[0020] The acrylic acid is neutralized by sodium hydroxide to a neutralization degree of 60-80%, and is stirred at a rotation speed of 200-300 rpm for 10-15 minutes, and then is stirred at a rotation speed of 400-500 rpm for 5-10 minutes;

[0021] The sulfonated lignin, the anticoagulant compound, the polylactic acid diacrylate, the azobisformamide, the nano-silicon dioxide and the photoinitiator are added to the neutralized acrylic acid solution, and are treated at an ultrasonic dispersion power of 200-300 W for 10-15 minutes, and then are treated at an ultrasonic dispersion power of 350-500 W for 5-10 minutes.

[0022] The application further provides that in the step S2, the mass fractions of the raw materials are as follows:

[0023] The acrylic acid is 200-300 parts, the sulfonated lignin is 5-15 parts, the anticoagulant compound is 5-15 parts, the polylactic acid diacrylate is 3-7 parts, the azobisformamide is 3-7 parts, the nano-silicon dioxide is 1-3 parts, the photoinitiator is 0.3-1 part, and the water is 400-600 parts.

[0024] The application further provides that the step S3 comprises:

[0025] The mixed solution is injected into a micro-channel reactor, the channel width is 100-300 mu m, and the mixed solution is injected at a flow rate of 0.5-1 mL / min first, and then is injected at a flow rate of 1-2 mL / min;

[0026] The polymerization reaction is carried out under pulse ultraviolet light irradiation, and the polymerization reaction is irradiated at a temperature of 10-15 °C, a power of 50-100 W and a pulse frequency of 3-5 Hz for 20-25 seconds first;

[0027] Then the polymerization reaction is irradiated at a temperature of 15-20 °C, a power of 100-150 W and a pulse frequency of 5-10 Hz for 10-15 seconds.

[0028] The application further provides that the azobisformamide is decomposed to generate nitrogen under the triggering of ultraviolet light, and a porous structure is formed, and the porosity after the decomposition is 70-90%, and the pore size distribution is 10-200 mu m.

[0029] The application is further provided with the step S4 comprising:

[0030] The high water-absorbing resin gel is immersed in the polylactic acid diacrylate solution, and first soaked at 20-25°C for 5-10 minutes, and then soaked at 25-30°C for 3-5 minutes;

[0031] The surface is cross-linked by ultraviolet light, and first irradiated at a power of 30-50W for 10-15 seconds, and then irradiated at a power of 50-70W for 5-10 seconds;

[0032] During drying, first treated at 60-70°C for 1-1.5 hours, and then treated at 70-80°C for 0.5-1 hour.

[0033] The application is further provided with the step S4 in the application comprising:

[0034] The concentration of the polylactic acid diacrylate solution is 5-15 wt%, and the mass ratio of the high water-absorbing resin gel to the polylactic acid diacrylate is 100:(3-7); and the particle size of the ground particles is 200-400μm.

[0035] The application is further provided with the step S2 in the application further comprising:

[0036] The S-nitrosoglutathione is added to the mixed solution, and first stirred at a rotation speed of 300-400 rpm for 5-10 minutes with an addition amount of 0.1-0.5 parts, and then stirred at a rotation speed of 500-600 rpm for 3-5 minutes with an addition amount of 0.1-0.5 parts.

[0037] Compared with the prior art, the application has the following beneficial effects:

[0038] The hydrolyzed tannic acid and nanocellulose are used to form a stable graft structure through Fe 3+ / H2O2 induced oxidative coupling reaction, and load citric acid to realize double anti-coagulation function. The hydrolyzed tannic acid is rich in polyphenol structure, which can effectively inhibit platelet aggregation and delay the start of the coagulation cascade reaction; the citric acid blocks the activation process of the coagulation factor by chelating calcium ions in the blood.

[0039] Azobisformamide is used as a foaming agent to generate nitrogen under pulsed ultraviolet light irradiation, and a porous structure is formed in situ. The permeation channel of the blood is effectively increased, and the problem of blocking the liquid absorption channel by the solidified blood on the surface is avoided.

[0040] The high water-absorbing resin prepared by the application not only improves the anti-coagulation performance, but also performs well in liquid absorption speed, capacity and product stability, and fully meets the needs of complex scenes such as female hygiene products. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 Process flow diagram of the present application; DETAILED DESCRIPTION

[0042] Reference Figure 1 Further description of the preparation method of the anticoagulant superabsorbent resin of the present application is as follows, including the following steps:

[0043] Example 1:

[0044] First step, preparation of the anticoagulant composite:

[0045] Hydrolyzed tannic acid and nanocellulose were mixed at a mass ratio of 2:1, and FeCl3·6H2O and H2O2 solution (Fe 3+ : H2O2 molar ratio 1:5) was added, where the mass ratio of FeCl3·6H2O to hydrolyzed tannic acid was 1:10, and the concentration of H2O2 was 10-20 wt%, and the reaction was stirred at pH 3 and 50°C for 2 hours, with nitrogen gas being passed to maintain an anaerobic environment, and the grafting product was formed by Fe 3+ catalyzing the oxidation of tannic acid to generate quinone intermediates, which underwent condensation reaction with the hydroxyl groups of nanocellulose. Subsequently, citric acid was added to the grafting product (mass ratio of citric acid to grafting product was 1:2), and the adsorption was stirred for 2 hours at 50°C under ultrasonic assistance (power 200), and the loading of citric acid was achieved through hydrogen bonding and electrostatic interaction. After the reaction was completed, centrifugal separation was performed (8000 rpm, 10 minutes), and the anticoagulant composite was obtained by drying at 60°C for 3 hours, with a Zeta potential of -3 mV and a specific surface area of 50 m² / g.

[0046] Second step, preparation of the mixed solution:

[0047] Before preparing the mixed solution, 200 parts of acrylic acid were neutralized to a neutralization degree of 60% with sodium hydroxide, and stepwise stirring was performed to ensure uniformity: first stirring at a speed of 200 rpm for 10 minutes, and then stirring at a speed of 400 rpm for 5 minutes. Subsequently, other ingredients were added to the neutralized acrylic acid solution, and the specific mixed solution contained the following components:

[0048] Sulfonated lignin 5 parts, anticoagulant complex 5 parts, poly(lactic acid-co-diacrylate) 3 parts, azobisformamide 3 parts, nano-silica 1 part, photoinitiator (2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone) 0.3 parts, and water 400 parts. The mixed solution was first treated under ultrasonic dispersion power of 200 W for 10 minutes, and then treated under ultrasonic dispersion power of 350 W for 5 minutes to ensure uniform dispersion of the components. Microencapsulated S-nitrosomethanol was added to the mixed solution, first with an addition amount of 0.1 parts under stirring at a rotational speed of 300 rpm for 5 minutes, and then with an addition amount of 0.1 parts under stirring at a rotational speed of 500 rpm for 3 minutes. The microencapsulation technology wraps S-nitrosomethanol with a polyurea shell to avoid its release of NO to interfere with the free radical reaction during UV polymerization.

[0049] Third step, UV micro-reaction polymerization:

[0050] The mixed solution was injected into a microchannel reactor with a channel width of 100 pm, and a segmented flow rate control was used: first injected into the initial segment (accounting for 50% of the total length) at a flow rate of 0.5 mL / min, and then injected into the subsequent segment (accounting for 50% of the total length) at a flow rate of 1 mL / min. The polymerization reaction was carried out under pulsed ultraviolet light irradiation, with 0.1 parts of benzophenone added as a photosensitizer to cooperate with azobisformamide decomposition. The specific conditions were: first irradiated at a temperature of 10 °C, a power of 50 W, and a pulse frequency of 3 Hz for 20 seconds, and then irradiated at a temperature of 15 °C, a power of 100 W, and a pulse frequency of 5 Hz for 10 seconds.

[0051] Fourth step, surface strengthening:

[0052] The superabsorbent resin gel was immersed in a poly(lactic acid-co-diacrylate) solution (concentration of 5 wt%, solvent being a water / ethanol mixture with a volume ratio of 1:1), and the mass ratio of the superabsorbent resin gel to poly(lactic acid-co-diacrylate) was 100:3. The immersion was carried out in steps: first immersed at 20 °C for 5 minutes, and then immersed at 25 °C for 3 minutes. Subsequently, surface crosslinking was carried out using ultraviolet light, first irradiated at a power of 30 W for 10 seconds, and then irradiated at a power of 50 W for 5 seconds. The drying process was carried out in steps: first treated at 60 °C for 1 hour, and then treated at 70 °C for 0.5 hour. After drying, a ball mill was used for grinding (rotational speed of 500 rpm, grinding time of 10 minutes), and anticoagulant superabsorbent resin particles with a particle size of 200 pm were obtained.

[0053] Example 2:

[0054] First step, preparation of anticoagulant complex: hydrolyzed tannic acid and nanocellulose were mixed at a mass ratio of 3:2, and FeCl3·6H2O and H2O2 solutions (Fe3 +: H2O2 molar ratio 1 :5), wherein the mass ratio of FeCl3-6H2O to hydrolyzed tannic acid is 1 :15, the concentration of H2O2 is 20 wt%, the reaction is stirred at pH 4 and temperature 55°C for 3 hours, nitrogen is introduced to maintain an anaerobic environment, the grafting product is formed by Fe3+ catalyzing the oxidation of tannic acid to generate quinone intermediates and the condensation reaction of the quinone intermediates with the hydroxyl groups of nanocellulose. Subsequently, citric acid is added to the grafting product (mass ratio of citric acid to grafting product is 1 :3), and the adsorption is stirred at 50°C for 2 hours under ultrasonic assistance (power 300W), so as to realize the loading of citric acid through hydrogen bonding and electrostatic interaction. After the reaction is completed, centrifugal separation (8000 rpm, 10 minutes) is performed, and drying is performed at 60°C for 3 hours to obtain an anticoagulant composite, the Zeta potential of which is -25 mV, and the specific surface area is 80 m² / g.

[0055] The second step, preparing a mixed solution: before preparing the mixed solution, 300 parts of acrylic acid are neutralized to a neutralization degree of 80% with sodium hydroxide, and stepwise stirring is performed to ensure uniformity: first stirring at a rotation speed of 300 rpm for 15 minutes, and then stirring at a rotation speed of 500 rpm for 10 minutes. Subsequently, other ingredients are added to the neutralized acrylic acid solution, and the specific mixed solution contains the following components: sulfonated lignin 15 parts, anticoagulant composite 15 parts, polylactic acid diacrylate 7 parts, azobisformamide 7 parts, nanosilica 3 parts, photoinitiator (2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone) 1 part and water 600 parts. The mixed solution is first treated under ultrasonic dispersion power of 300W for 15 minutes, and then treated under ultrasonic dispersion power of 500W for 10 minutes, so as to ensure uniform dispersion of the components. Microencapsulated S-nitrosomethanol is added to the mixed solution, first with an addition amount of 0.5 parts and stirring at a rotation speed of 400 rpm for 10 minutes, and then with an addition amount of 0.5 parts and stirring at a rotation speed of 600 rpm for 5 minutes.

[0056] The third step, UV micro-reaction polymerization: the mixed solution is injected into a micro-channel reactor, the channel width is 300μm, and segmented flow rate control is adopted: first injecting at 1 mL / min into the initial segment (accounting for 60% of the total length), and then injecting at 2 mL / min into the subsequent segment (accounting for 40% of the total length). The polymerization reaction is carried out under pulsed ultraviolet light irradiation, and 0.3 parts of benzophenone is added as a photosensitizer to cooperate with azobisformamide decomposition. The specific conditions are: first irradiation at a temperature of 15°C, a power of 100W and a pulse frequency of 5 Hz for 25 seconds, and then irradiation at a temperature of 20°C, a power of 150W and a pulse frequency of 10 Hz for 15 seconds.

[0057] Step 4, Surface Strengthening: The superabsorbent polymer (SAP) gel was immersed in a polylactic acid diacrylate solution (15 wt% concentration, water / ethanol mixture, volume ratio 1:1), with a SAP gel to PLA mass ratio of 100:7. Stepwise immersion: First, immersion at 25°C for 10 minutes, then at 30°C for 5 minutes. Subsequently, surface crosslinking was performed using ultraviolet light, first irradiated at 50W for 15 seconds, then at 70W for 10 seconds. The drying process was carried out in steps: first treated at 70°C for 1.5 hours, then at 80°C for 1 hour. After drying, the mixture was ground using a ball mill (500 rpm, grinding time 20 minutes) to obtain anticoagulant SAP particles with a particle size of 400 μm.

[0058] Example 3:

[0059] First step: Preparation of the anticoagulant complex:

[0060] Hydrolyzed tannic acid and nanocellulose were mixed at a mass ratio of 2.5:1.5, and FeCl3·6H2O and H2O2 solution was added (Fe3... + The reaction mixture was prepared with a 1:5 molar ratio of FeCl3·6H2O to hydrolyzed tannic acid (1:12.5 mass ratio) and a 15wt% H2O2 concentration. Nitrogen gas was introduced during the reaction, and the mixture was stirred at pH 3.5 and 52.5°C for 2.5 hours to form a grafted product. Citric acid was then added to the grafted product, and the mixture was adsorbed at 50°C for 2 hours with ultrasonic assistance. After centrifugation, the mixture was dried at 60°C for 3 hours to obtain the anticoagulant complex.

[0061] Step 2: Preparation of the mixed solution:

[0062] Acrylic acid was neutralized with sodium hydroxide to a neutralization degree of 70%, and stirred at 250 rpm for 12.5 minutes, followed by stirring at 450 rpm for 7.5 minutes. The following components were added to the neutralized acrylic acid solution: 250 parts acrylic acid, 10 parts sulfonated lignin, 10 parts anticoagulant complex, 5 parts polylactic acid diacrylate, 5 parts azodicarbonamide, 2 parts nano-silica, 0.65 parts photoinitiator, and 500 parts water. This mixture was first ultrasonically dispersed at 250W for 12.5 minutes, followed by ultrasonic dispersion at 425W for 7.5 minutes. Finally, S-nitrosothiol was added, first at a rate of 0.3 parts, and stirred at 350 rpm for 7.5 minutes, followed by a rate of 0.3 parts, and stirred at 550 rpm for 4 minutes.

[0063] Third step, UV microreaction polymerization:

[0064] The mixed solution was injected into the micro-channel reactor with a channel width of 200 pm, first at a flow rate of 0.75 mL / min, and then at a flow rate of 1.5 mL / min; the polymerization reaction was carried out under pulsed ultraviolet light irradiation, first at a temperature of 12.5 °C, a power of 75 W, and a pulse frequency of 4 Hz for 22.5 seconds; and then at a temperature of 17.5 °C, a power of 125 W, and a pulse frequency of 7.5 Hz for 12.5 seconds, to obtain a superabsorbent resin gel.

[0065] Fourth step, surface reinforcement:

[0066] The superabsorbent resin gel was immersed in a polylactic acid diacrylate solution with a concentration of 10 wt%, and the mass ratio of the superabsorbent resin gel to polylactic acid diacrylate was 100:5; first immersed at 22.5 °C for 7.5 minutes, and then immersed at 27.5 °C for 4 minutes; surface crosslinking was performed using ultraviolet light, first at a power of 40 W for 12.5 seconds, and then at a power of 60 W for 7.5 seconds; during drying, first treated at 65 °C for 1.25 hours, and then treated at 75 °C for 0.75 hours, and after grinding, the particle size was 300 pm.

[0067] Comparative Example 1: Anti-coagulation complex without citric acid loading

[0068] First step: hydrolyzed tannic acid and nanocellulose were mixed at a mass ratio of 2:2, and FeCl3·6H2O and H2O2 solutions (Fe 3+ : H2O2 molar ratio 1:5) were added, wherein the mass ratio of FeCl3·6H2O to hydrolyzed tannic acid was 1:10, and the concentration of H2O2 was 10–20 wt%, and the reaction was stirred at pH 3 and a temperature of 50 °C for 2 hours, and nitrogen was passed through to form a grafted product; the citric acid loading step was omitted, and after centrifugation, drying was performed at 60 °C for 3 hours to obtain a complex containing only tannic acid-nanocellulose.

[0069] Second step: same as Example 1 (acrylic acid 200 parts, sulfonated lignin 5 parts, complex 5 parts, polylactic acid diacrylate 3 parts, azodicarbonamide 3 parts, nanosilica 1 part, photoinitiator 0.3 parts, water 400 parts, etc.).

[0070] Third step: same as Example 1.

[0071] Fourth step: same as Example 1.

[0072] Comparative Example 2: sodium bicarbonate was used to replace azodicarbonamide

[0073] First step: same as Example 1.

[0074] Second step: neutralize the acrylic acid with sodium hydroxide to a neutralization degree of 60%, first stirring at 200 rpm for 10 minutes, then at 400 rpm for 5 minutes; add the following components: sulfonated lignin 5 parts, anticoagulant complex 5 parts, polylactic acid diacrylate 3 parts, sodium bicarbonate 3 parts (instead of azodicarbonamide), nano-silicon dioxide 1 part, photoinitiator 0.3 parts, and water 400 parts, ultrasonic dispersion power 200 W for 10 minutes, then 350 W for 5 minutes; add S-nitrosothiol 0.1 parts, stirring at 300 rpm for 5 minutes, then at 500 rpm for 3 minutes.

[0075] Third step: same as Example 1, sodium bicarbonate decomposes in an acidic environment to generate CO2, forming a porous structure.

[0076] Fourth step: same as Example 2.

[0077] Comparative Example 3: Single traditional crosslinking agent instead of gradient crosslinking

[0078] First step: same as Example 1.

[0079] Second step: same as Example 1.

[0080] Third step: same as Example 1.

[0081] Fourth step: immerse the superabsorbent resin gel in a 5 wt% N,N'-methylenebisacrylamide (MBAA) solution (instead of polylactic acid diacrylate), mass ratio 100:3, first soak at 25°C for 5 minutes; ultraviolet light crosslinking is irradiated at a power of 30W for 10 seconds (single crosslinking); drying is treated at 60°C for 1 hour, then at 70°C for 0.5 hours, and grinding to a particle size of 200μm.

[0082] The anticoagulant superabsorbent resins obtained in Examples 1 to 3 and Comparative Examples 1 to 3 are tested for performance, and the test method is:

[0083] Blood absorption time measurement: take 2.0 g of resin sample, uniformly disperse in 25 mL of mixed blood (fresh pig blood: artificial blood = 1:1, viscosity 3.5 mPa·s) at 37°C, start timing in a magnetic stirrer (300 rpm), observe until the resin completely absorbs the liquid, presents no lumps, no undissolved white particles, record the total time (seconds). Refer to GB / T 22875-2020 "Absorbent sanitary product blood absorption time measurement", repeat 3 times to take the average.

[0084] Blood absorption amount (mL / g): accurately weigh 1.00 g of dry resin sample, put it into a 50 mL beaker.

[0085] Add 25 mL of pre-heated to 37°C simulated blood (fresh pig blood: artificial blood = 1:1, viscosity 3.5 mPa-s), gently stir to homogeneity. Let stand for 30 minutes, ensuring the resin fully absorbs the liquid.

[0086] Wrap the sample with filter paper, place in a centrifuge, centrifuge at 3000 rpm for 5 minutes, remove the unabsorbed liquid. Weigh the sample mass after centrifugation, calculate the blood uptake:

[0087]

[0088] Whole blood clotting time: Take 10 mL of fresh pig blood (after anticoagulation treatment, 37°C incubation), add 0.5 g of resin sample, gently shake to homogeneity. Immediately measure the clotting curve using a coagulation instrument (e.g. TEG or clotting time meter).

[0089] Record the time from adding the resin to the blood starting to clot, compare with the blank control (without resin), calculate the clotting time extension.

[0090] Specific surface area (m² / g): Take 0.5 g of dried sample, place in a BET test tube. Degas at 100°C under vacuum for 4 hours, remove moisture and impurities. Measure the adsorption / desorption isotherm using a nitrogen adsorption instrument (e.g. Micromeritics ASAP 2460). Calculate the specific surface area according to the BET model.

[0091] Porosity (%) : Weigh about 1 g of dried sample, place in the sample chamber of a mercury porosimeter (e.g. AutoPore IV 9500). Apply a pressure range of 0.5-60000 psi, record the mercury intrusion volume, calculate the porosity.

[0092] Centrifuge water retention (g / g): Weigh 1.00 g of dried sample, immerse in 0.9% NaCl physiological saline for 30 minutes.

[0093] Wrap the sample with filter paper, place in a centrifuge, centrifuge at 3000 rpm for 5 minutes, weigh the mass after centrifugation, calculate the water retention.

[0094] Pressure absorption rate (g / g): Use an absorbency under load tester (AUL), apply a pressure of 0.7 psi. Weigh 0.16 g of sample, evenly spread on the bottom of the test cup. Add 0.9% NaCl physiological saline, record the mass of absorbed liquid, calculate the pressure absorption rate.

[0095] Dryness (residual liquid mg / cm²): Weigh 1.00 g of sample, immerse in 0.9% NaCl physiological saline for 30 minutes.

[0096] The sample after absorbing liquid was placed on filter paper, and a pressure of 0.7 psi was applied for 10 minutes. The weight gain of the filter paper was weighed, and the amount of back penetration per square centimeter was calculated.

[0097] The test results are shown in Table 1.

[0098] Table 1:

[0099]

[0100] As can be seen from Table 1, the examples show that the blood absorption times of Examples 1-3 are 8 seconds, 5 seconds and 6 seconds, respectively, which are significantly lower than those of the comparative examples. This is due to the fact that the anticoagulant compound (the synergistic effect of hydrolyzed tannic acid and citric acid) delays blood coagulation, so that the resin can quickly disperse and absorb blood, and the uniform porous structure (porosity 70-90%) generated by azodicarbonamide accelerates blood penetration. The blood absorption time of Example 2 is the shortest (5 seconds), which is related to its highest specific surface area (80 m² / g) and porosity (90%).

[0101] Comparative Example 1 (without citric acid loading): the blood absorption time is 25 seconds, which is much higher than that of the examples. The reason is that the calcium ion chelation function of citric acid is lacking, and only the inhibition of platelet aggregation by tannic acid is not enough to effectively delay blood coagulation (the whole blood coagulation time is only 6.5 minutes), resulting in the formation of a blood clot before absorption, which hinders the penetration of blood.

[0102] Comparative Example 2 (sodium bicarbonate instead of azodicarbonamide): the blood absorption time is 18 seconds, which is slower than that of the examples. Sodium bicarbonate decomposes to generate CO2 in an acidic environment, and the porosity (55%) and specific surface area (30 m² / g) are low, and the pore distribution is not uniform enough, which affects the rapid penetration of blood.

[0103] Comparative Example 3 (single MBAA crosslinking): the blood absorption time is 15 seconds, which is slightly better than that of Comparative Examples 1 and 2, but still not as good as that of the examples. Although the single crosslinking maintains a certain liquid absorption capacity, the lack of gradient structure leads to a decrease in the utilization rate of internal pores, limiting the speed of blood penetration.

[0104] The present application significantly shortens the blood absorption time (5-8 seconds) through the synergistic effect of the anticoagulant compound and the porous structure of azodicarbonamide, which is much better than that of the comparative examples (15-25 seconds). This indicates the key role of the dual anticoagulant mechanism and the efficient porous design in improving the efficiency of blood absorption, which provides excellent performance basis for sanitary absorption products.

[0105] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any changes and substitutions within the scope of the technical solutions of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing an anticoagulant superabsorbent resin, characterized in that, The method comprises the following steps: S1, preparing an anticoagulant complex: hydrolyzed tannic acid is combined with nanocellulose through oxidative coupling reaction, and then loaded with citric acid to obtain the anticoagulant complex; S2, preparing a mixed solution: acrylic acid, sulfonated lignin, the anticoagulant complex, polylactic acid diacrylate, azobisformamide, nanosilica and a photoinitiator are dissolved in water to obtain the mixed solution; S3, UV micro-reaction polymerization: the mixed solution is injected into a micro-channel reactor, and polymerization reaction is carried out under pulsed ultraviolet light irradiation to obtain a superabsorbent resin gel; S4, surface strengthening: the superabsorbent resin gel is immersed in a polylactic acid diacrylate solution, and surface crosslinking is carried out under ultraviolet light irradiation, and then the superabsorbent resin particles are obtained after drying and grinding.

2. The method for preparing an anticoagulant superabsorbent resin according to claim 1, characterized in that, The S1 comprises the following steps: S11, mixing hydrolyzed tannic acid and nanocellulose at a mass ratio of (2-3):(1-2), adding FeCl3·6H2O and H2O2 solution, stirring and reacting at pH 3-4 and a temperature of 50-55°C for 2-3 hours to perform oxidative coupling to form a grafted product; S12, adding citric acid to the grafted product at a mass ratio of (1-2):3, adsorbing under ultrasonic assistance at a temperature of 50°C for 2 hours, and then drying at 60°C for 3 hours after centrifugation to obtain the anticoagulant complex.

3. The method for preparing an anticoagulant superabsorbent resin according to claim 2, characterized in that, In the step S11, the mass ratio of FeCl3·6H2O to hydrolyzed tannic acid is 1:(10-15); the concentration of H2O2 is 10-20 wt%, and nitrogen is passed during the reaction process. The Zeta potential of the complex after loading with citric acid is -35 to -25 mV, and the specific surface area is 50-80 m² / g. The step S2 comprises:

4. The method for preparing an anticoagulant superabsorbent resin according to claim 1, characterized in that, The acrylic acid is neutralized to a neutralization degree of 60-80% with sodium hydroxide, and then stirred at a rotation speed of 200-300 rpm for 10-15 minutes and at a rotation speed of 400-500 rpm for 5-10 minutes; Sulfonated lignin, the anticoagulant complex, polylactic acid diacrylate, azobisformamide, nanosilica and a photoinitiator are added to the neutralized acrylic acid solution, and then treated under ultrasonic dispersion power of 200-300 W for 10-15 minutes and under ultrasonic dispersion power of 350-500 W for 5-10 minutes. In the step S2, the mass fractions of the raw materials are as follows:

5. The method of claim 4, wherein the anticoagulant superabsorbent resin is prepared by adding 0.1 to 5 parts by weight of the anticoagulant to 100 parts by weight of the superabsorbent resin. Acrylic acid 200-300 parts, sulfonated lignin 5-15 parts, anticoagulant complex 5-15 parts, polylactic acid diacrylate 3-7 parts, azobisformamide 3-7 parts, nanosilica 1-3 parts, photoinitiator 0.3-1 part, and water 400-600 parts. The step S3 comprises:

6. The method of claim 5, wherein the anticoagulant superabsorbent resin is prepared by adding 0.1 to 5 parts by weight of the anticoagulant to 100 parts by weight of the superabsorbent resin. The mixed solution is injected into a micro-channel reactor, and the channel width is 100-300 μm; the mixed solution is first injected at a flow rate of 0.5-1 mL / min, and then injected at a flow rate of 1-2 mL / min; Polymerization reaction is carried out under pulsed ultraviolet light irradiation; the irradiation is first carried out at a temperature of 10-15°C, a power of 50-100 W and a pulse frequency of 3-5 Hz for 20-25 seconds; ​ Then irradiate for 10-15 seconds at a temperature of 15-20 °C, a power of 100-150 W, and a pulse frequency of 5-10 Hz.

7. The method for preparing an anticoagulant superabsorbent resin according to claim 6, characterized in that, The azobisformamide is decomposed to generate nitrogen under the triggering of ultraviolet light, forming a porous structure with a porosity of 70-90% and a pore size distribution of 10-200 μm after decomposition.

8. The method for preparing an anticoagulant superabsorbent resin according to claim 1, characterized in that, The step S4 comprises: Soak the superabsorbent resin gel in the polylactic acid diacrylate solution, first at 20-25 °C for 5-10 minutes, and then at 25-30 °C for 3-5 minutes; Use ultraviolet light for surface crosslinking, first at a power of 30-50 W for 10-15 seconds, and then at a power of 50-70 W for 5-10 seconds; When drying, first treat at 60-70 °C for 1-1.5 hours, and then at 70-80 °C for 0.5-1 hour.

9. The method of claim 8, wherein the anticoagulant superabsorbent resin is prepared by adding 0.1 to 5 parts by weight of the anticoagulant to 100 parts by weight of the superabsorbent resin. In the step S4: The concentration of the polylactic acid diacrylate solution is 5-15 wt%, and the mass ratio of the superabsorbent resin gel to the polylactic acid diacrylate is 100:(3-7); the particle size of the ground particles is 200-400 μm.

10. The method for preparing an anticoagulant superabsorbent resin according to claim 1, characterized in that, The step S2 further comprises: Add S-nitrosothiol to the mixed solution, first at an addition amount of 0.1-0.5 parts at a rotation speed of 300-400 rpm for 5-10 minutes, and then at an addition amount of 0.1-0.5 parts at a rotation speed of 500-600 rpm for 3-5 minutes.

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