Degradable crystal mud as well as preparation method and application thereof

Abstract

The invention relates to the field of stationery, in particular to degradable crystal mud as well as a preparation method and application thereof. The degradable crystal mud at least comprises the following raw materials in parts by mass: 40-55 parts of polyvinyl alcohol, 15-25 parts of degradable resin and 5-10 parts of a compound bio-based cross-linking agent. According to the prepared crystal mud material, the plasticity, the stability, the mechanical property and other properties are greatly improved while the excellent degradability and low toxicity of the crystal mud material are guaranteed, the water loss hardening phenomenon is reduced, the comprehensive performance is effectively improved, the repeated use requirement of culture and education scenes is met, the service life of the crystal mud is prolonged, and the use quality of the crystal mud is improved.

Description

Technical Field

[0001] The present application relates to the field of stationery and educational supplies, and more specifically mentions a biodegradable crystal mud and its preparation method and application. Background Art

[0002] Crystal mud, a semi-solid gel material, is widely used in arts and crafts and sensory training programs in the cultural and educational fields due to its rich colors, strong ductility, and unique tactile feel. Traditionally, crystal mud is a popular children's toy and handicraft material in the cultural and educational supplies sector, thanks to its excellent plasticity. However, traditional crystal mud is often made from non-degradable materials, and its waste can cause long-term environmental pollution. Furthermore, the borax crosslinking agent commonly used is toxic to the human body, especially for children. Accidental ingestion or long-term exposure can cause poisoning symptoms. Therefore, reducing the toxicity of crystal mud and enhancing its degradability have become important research topics for researchers in the field.

[0003] For example, patent CN108948615A provides a DIY non-toxic crystal mud for educational purposes and a preparation method thereof. It replaces borax with a borate cross-linking agent to reduce the toxicity of the crystal mud, and adopts a compound of crystal mud active agents to improve the plasticity and playability of the crystal mud. However, the degradability and other comprehensive properties have not been significantly improved. In addition, existing degradable alternatives, such as starch-based gels, also generally have problems such as low mechanical strength and easy water loss and hardening (24-hour weight loss rate >30%), which cannot meet the needs of reuse in cultural and educational scenarios. Summary of the Invention

[0004] As mentioned above, how to further improve the degradability, strength, and flexibility of crystal mud has become the focus of research. Through continuous research in this field, the applicant has finally proposed a degradable crystal mud and its preparation method. The crystal mud material prepared by this application, while ensuring its excellent degradability and low toxicity, greatly improves its plasticity, stability, and mechanical properties, reduces the phenomenon of water loss and hardening, and effectively improves its comprehensive performance, meeting the needs of repeated use in cultural and educational scenarios, and improving the service life and quality of the crystal mud.

[0005] The invention discloses a degradable crystal mud, whose raw materials at least include, by weight, 40 to 55 parts of polyvinyl alcohol, 15 to 25 parts of degradable resin and 5 to 10 parts of compounded bio-based cross-linking agent.

[0006] In a preferred embodiment, the degree of polymerization of the polyvinyl alcohol is 1600-1900.

[0007] In a preferred embodiment, the alcoholysis degree of the polyvinyl alcohol is 80-90%.

[0008] In a preferred embodiment, the preparation method of the biodegradable resin specifically includes the following steps: S1: adding polybutylene succinate to an organic solvent and heating and stirring to dissolve; S2: adding dioctyl itaconate, glycidyl acrylate and vinyl pyrrolidone, passing nitrogen for protection, and then adding benzoyl peroxide to keep warm for reaction; S3: pouring the product into ice ethanol for precipitation, filtering, washing 2 to 3 times, vacuum drying and crushing to obtain.

[0009] In a preferred embodiment, the preparation method of the biodegradable resin specifically includes the following steps: S1: adding polybutylene succinate to an organic solvent and stirring at 100-120 rpm at 70-75°C for 1.5-2 hours; S2: adding dioctyl itaconate, glycidyl acrylate and vinyl pyrrolidone, passing nitrogen protection, heating to 80-85°C, adding benzoyl peroxide and keeping warm for 6-7 hours; S3: after the reaction is completed, pouring into ice ethanol for precipitation, filtering and washing with deionized water for 2-3 times, vacuum drying at 65-70°C for 8-10 hours, and then crushing to a particle size of 50-100 μm to obtain the product.

[0010] In a preferred embodiment, the mass ratio of polybutylene succinate, dioctyl itaconate, glycidyl acrylate and vinyl pyrrolidone is (70-85): (8-12): (6-10): (5-9).

[0011] In a preferred embodiment, the mass ratio of polybutylene succinate, dioctyl itaconate, glycidyl acrylate and vinyl pyrrolidone is (75-80): (9-11): (7-8): (5-7).

[0012] The addition of the above-mentioned degradable resin not only greatly improves the degradability of the crystal mud, but it can also effectively achieve mechanical enhancement of the system, improve plasticity, service life and quality. As an auxiliary raw material, the degradable resin makes up for the insufficient mechanical strength of the pure PVA system through physical entanglement and chemical cross-linking between molecular chains, and the long-chain alkyl group plays a lubricating role in the PVA system, lowering the glass transition temperature, and promoting the alternating arrangement of the hydrophilicity and hydrophobicity of the pyrrolidone ring to form a low friction coefficient layer on the surface, thereby ultimately improving the brittleness of the pure PVA system and giving the crystal mud a brushed texture. On the other hand, the ester bonds it contains preferentially hydrolyze to form succinic acid and butanediol in a humid environment, lowering the local pH, and promoting the breakage of the PVA molecular chain in a long-term degradation environment, thereby ensuring the comprehensive performance of early use while enhancing the degradability in the later stage.

[0013] In a preferred embodiment, the compounded bio-based cross-linking agent is a composition of castor oil-based polyester polyol, tannic acid and chitosan quaternary ammonium salt.

[0014] In a preferred embodiment, the mass ratio of the castor oil-based polyester polyol, tannic acid and chitosan quaternary ammonium salt is (5-7): (3-4): (1-3).

[0015] In a preferred embodiment, the mass ratio of the castor oil-based polyester polyol, tannic acid and chitosan quaternary ammonium salt is (6-6.5): (3.2-3.5): (1.8-2.4).

[0016] In a preferred embodiment, the OH value of the castor oil-based polyester polyol is 100 to 120 mgKOH / g.

[0017] In a preferred embodiment, the mass ratio of the polyvinyl alcohol, the degradable resin and the compounded bio-based cross-linking agent is (45-55): (18-25): (6-9).

[0018] In a preferred embodiment, the mass ratio of the polyvinyl alcohol, the degradable resin and the compounded bio-based cross-linking agent is (45-50): (20-22): (7-8).

[0019] In a preferred embodiment, the raw materials of the degradable crystal mud, calculated by mass, also include: 1 to 3 parts of pH regulator, 8 to 15 parts of softener, 10 to 18 parts of plasticizer, 3 to 6 parts of degradation accelerator, 2 to 5 parts of moisturizer, 0.1 to 0.3 parts of preservative, 1 to 2.5 parts of color paste, 2 to 4 parts of powder, and 150 to 250 parts of deionized water.

[0020] In a preferred embodiment, the mass ratio of the polyvinyl alcohol, the softener and the plasticizer is (45-55): (10-13): (11-16).

[0021] In a preferred embodiment, the mass ratio of the polyvinyl alcohol, the softener and the plasticizer is (45-50): (11-12): (13-15).

[0022] In a preferred embodiment, the pH adjuster is at least one of citric acid, ascorbic acid and tartaric acid.

[0023] In a preferred embodiment, the pH adjuster is citric acid or ascorbic acid.

[0024] In a preferred embodiment, the softener is a composition of hydrogenated rosin glycerol ester and epoxidized soybean oil.

[0025] In a preferred embodiment, the mass ratio of hydrogenated rosin glycerol ester to epoxidized soybean oil is (5-9):(1-3).

[0026] In a preferred embodiment, the mass ratio of hydrogenated rosin glycerol ester to epoxidized soybean oil is (6-8):(1.5-2.5).

[0027] In a preferred embodiment, the plasticizer is at least one of tributyl citrate, acetyl triethyl citrate, gluconolactone and dioctyl adipate.

[0028] In a preferred embodiment, the plasticizer is tributyl citrate or gluconolactone.

[0029] In a preferred embodiment, the degradation accelerator is at least one of polyhydroxybutyrate, sodium lignin sulfonate, microcrystalline cellulose and sodium alginate.

[0030] In a preferred embodiment, the degradation accelerator is polyhydroxybutyrate or sodium alginate.

[0031] In a preferred embodiment, the moisturizing agent is at least one of glycerin, sorbitol, xylitol and sodium hyaluronate.

[0032] In a preferred embodiment, the moisturizing agent is sorbitol or sodium hyaluronate.

[0033] In a preferred embodiment, the moisturizing agent is sorbitol.

[0034] In a preferred embodiment, the preservative is at least one of sodium dehydroacetate, 1,2-hexanediol and ε-polylysine.

[0035] In a preferred embodiment, the preservative is sodium dehydroacetate.

[0036] In a preferred embodiment, the color paste is at least one of beetroot red, anthocyanin and β-carotene.

[0037] In a preferred embodiment, the powder is at least one of mica powder, shell powder, pearl powder and plant cellulose.

[0038] In a preferred embodiment, the powder is pearl powder or shell powder.

[0039] A preferred embodiment, the preparation method of the crystal mud specifically includes the following steps: S1: adding polyvinyl alcohol to deionized water, heating in a water bath at 85-90°C, stirring at a speed of 120-150 rpm for 1.5-2h, then cooling to 70-75°C, adding a degradable resin softener and a plasticizer, and stirring at a speed of 180-200 rpm for 30-40min; S2: adding a compound bio-based cross-linking agent, keeping warm at 65-70°C for 1-1.5h, then adding a degradation accelerator, a moisturizer and a preservative, and stirring at 50-55°C and 100-120 rpm for 30-40min until uniform; S3: adding color paste and powder, stirring at 120-150 rpm at 40-50°C for 20-30min, and finally adding a pH adjuster and stirring to adjust the pH of the system to 6.5-7.5.

[0040] The present application further limits the application of the prepared degradable crystal mud in stationery and educational supplies.

[0041] Practical significance and effects:

[0042] 1. The crystal mud material prepared in this application, while ensuring its own excellent degradability and low toxicity, greatly improves its plasticity, stability, mechanical properties and other properties, reduces water loss and hardening, effectively improves the comprehensive performance, meets the needs of repeated use in cultural and educational scenes, and improves the service life and quality of the crystal mud.

[0043] 2. By adding degradable resin, physical entanglement and chemical cross-linking are used to make up for the insufficient mechanical strength of the pure PVA system. The long-chain alkyl group plays a lubricating role in the PVA system, lowering the glass transition temperature and promoting the alternating arrangement of the hydrophilicity and hydrophobicity of the pyrrolidone ring to form a low friction coefficient layer on the surface, thereby ultimately improving the brittleness of the pure PVA system and giving the crystal mud a brushed texture.

[0044] 3. Further add a compound bio-based cross-linking agent to form ester bonds with the hydroxyl groups of PVA through long-chain fatty acid structures to form a "soft segment" network, giving the material high ductility. The polyphenol structure of tannic acid condenses with the aldehyde group of glutaraldehyde to form a Schiff base, which is combined with the hydroxyl groups of PVA through hydrogen bonds and covalent bonds to construct high-density "hard segment" cross-linking points. Finally, the quaternary ammonium cations are combined with the hydroxyl groups of PVA through electrostatic action to form a reversible ionic cross-linking network, thereby enhancing the comprehensive performance of the crystal mud. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a physical picture of the biodegradable crystal mud product prepared in Example 1 of the present application.

[0046] Figure 2 This is a physical picture of the biodegradable crystal mud product prepared in Example 2 of this application.

[0047] Figure 3 This is a physical picture of the biodegradable crystal mud product prepared in Example 3 of the present application. DETAILED DESCRIPTION

[0048] Example 1

[0049] The raw materials of degradable crystal mud, calculated by mass, include: 48.6 parts of polyvinyl alcohol, 20.4 parts of degradable resin, 8 parts of compound bio-based cross-linking agent, 1.6 parts of pH adjuster, 11.5 parts of softener, 13.2 parts of plasticizer, 4.8 parts of degradation accelerator, 3.5 parts of moisturizer, 0.1 part of preservative, 1.8 parts of color paste, 3.1 parts of powder, and 160 parts of deionized water.

[0050] The polyvinyl alcohol is PVA-1788, with a degree of polymerization of 1700 and a degree of alcoholysis of 88%.

[0051] The biodegradable resin, calculated by mass, specifically includes the following steps: S1: adding 78.5 parts of polybutylene succinate to 200 parts of tetrahydrofuran, and stirring at 120 rpm at 70°C for 2 hours; S2: adding 10 parts of dioctyl itaconate, 7.5 parts of glycidyl acrylate and 6 parts of vinyl pyrrolidone, after passing nitrogen protection, heating to 80-85°C, adding 1.4 parts of benzoyl peroxide and keeping warm for reaction for 6.5 hours; S3: after the reaction is completed, pouring into 300 parts of icy ethanol for precipitation, filtering, washing with deionized water 33 times, vacuum drying at 70°C for 10 hours, and then crushing to a particle size of 60 μm to obtain the biodegradable resin.

[0052] Polybutylene succinate, brand C1200, is from Shanghai Yilun Plastics, China.

[0053] The compounded bio-based cross-linking agent is a composition of castor oil-based polyester polyol, tannic acid and chitosan quaternary ammonium salt, with a mass ratio of 6.2:3.3:2.

[0054] Castor oil-based polyester polyol has an OH value of 120 mgKOH / g, is a premium grade product from Huipeng Chemical in Jining, China.

[0055] Chitosan quaternary ammonium salt, CP grade, was obtained from Lanabai Pharmaceutical Chemicals, Wuhan, China.

[0056] The pH regulator is citric acid; the softener is a combination of hydrogenated rosin glycerol ester and epoxidized soybean oil, with a mass ratio of 7.5:2; the plasticizer is tributyl citrate; the degradation accelerator is sodium alginate; the moisturizer is sorbitol; and the preservative is sodium dehydroacetate.

[0057] The powder is shell powder 1500 mesh and the color paste is beet red.

[0058] The preparation method of crystal mud in this embodiment specifically includes the following steps: S1: adding polyvinyl alcohol to deionized water, heating in a water bath at 90°C, stirring at 120rpm for 1.5h, then cooling to 75°C, adding a degradable resin softener and a plasticizer, and stirring at 180rpm for 35min; S2: adding a compounded bio-based cross-linking agent, keeping warm at 70°C for 1.5h, then adding a degradation accelerator, a moisturizer and a preservative, and stirring at 55°C and 120rpm for 30min until uniform; S3: adding color paste and powder, stirring at 150rpm at 45°C for 25min, and finally adding a pH adjuster and stirring to adjust the pH of the system to 6.6.

[0059] The final product of the degradable crystal mud obtained in this embodiment is as follows Figure 1 shown.

[0060] Example 2

[0061] The difference between Example 2 and Example 1 is that the raw materials of the degradable crystal mud, calculated by mass, include: 52.5 parts of polyvinyl alcohol, 18.5 parts of degradable resin, 9 parts of compound bio-based cross-linking agent, 1.6 parts of pH regulator, 11.5 parts of softener, 13.2 parts of plasticizer, 4.8 parts of degradation accelerator, 3.5 parts of moisturizer, 0.1 part of preservative, 1.8 parts of color paste, 3.1 parts of powder, and 160 parts of deionized water.

[0062] The compounded bio-based cross-linking agent is a composition of castor oil-based polyester polyol, tannic acid and chitosan quaternary ammonium salt, with a mass ratio of 7:3:3.

[0063] The pigment is anthocyanin.

[0064] Other embodiments are the same.

[0065] The final product of the degradable crystal mud obtained in this embodiment is as follows Figure 2 shown.

[0066] Example 3

[0067] The difference between Example 3 and Example 1 is that the raw materials of the degradable crystal mud, calculated by mass, include: 46.5 parts of polyvinyl alcohol, 22.5 parts of degradable resin, 6.5 parts of compound bio-based cross-linking agent, 1.6 parts of pH regulator, 11.5 parts of softener, 13.2 parts of plasticizer, 4.8 parts of degradation accelerator, 3.5 parts of moisturizer, 0.1 part of preservative, 1.8 parts of color paste, 3.1 parts of powder, and 160 parts of deionized water.

[0068] The compound bio-based cross-linking agent is a composition of castor oil-based polyester polyol, tannic acid and chitosan quaternary ammonium salt, with a mass ratio of 5.5:4:1.5.

[0069] The color paste is beta-carotene.

[0070] Other embodiments are the same.

[0071] The final product of the degradable crystal mud obtained in this embodiment is as follows Figure 3 shown.

[0072] Comparative Example 1

[0073] The difference between Comparative Example 1 and Example 1 is that the raw materials of the degradable crystal mud, in parts by mass, include: 59 parts of polyvinyl alcohol, 10 parts of degradable resin, 8 parts of compound bio-based cross-linking agent, 1.6 parts of pH regulator, 11.5 parts of softener, 13.2 parts of plasticizer, 4.8 parts of degradation accelerator, 3.5 parts of moisturizer, 0.1 part of preservative, 1.8 parts of color paste, 3.1 parts of powder, and 160 parts of deionized water.

[0074] Other embodiments are the same.

[0075] Comparative Example 2

[0076] The difference between Comparative Example 2 and Example 1 is that the raw materials of the degradable crystal mud, in parts by mass, include: 55 parts of polyvinyl alcohol, 20.4 parts of degradable resin, 2.5 parts of compound bio-based cross-linking agent, 1.6 parts of pH regulator, 11.5 parts of softener, 13.2 parts of plasticizer, 4.8 parts of degradation accelerator, 3.5 parts of moisturizer, 0.1 part of preservative, 1.8 parts of color paste, 3.1 parts of powder, and 160 parts of deionized water.

[0077] Other embodiments are the same.

[0078] Comparative Example 3

[0079] The difference between Comparative Example 3 and Example 1 is that the compounded bio-based cross-linking agent is a composition of castor oil-based polyester polyol, tannic acid and chitosan quaternary ammonium salt, with a mass ratio of 2:6:4.

[0080] Other embodiments are the same.

[0081] Comparative Example 4

[0082] The difference between Comparative Example 4 and Example 1 is that the compounded bio-based cross-linking agent is a composition of castor oil-based polyester polyol, tannic acid and chitosan quaternary ammonium salt, with a mass ratio of 9:1:0.5.

[0083] Other embodiments are the same.

[0084] Comparative Example 5

[0085] The difference between Comparative Example 5 and Example 1 is that the degradable resin, in parts by mass, specifically includes the following steps: S1: adding 100 parts of polybutylene succinate to 200 parts of tetrahydrofuran, stirring at 120 rpm at 70°C for 2h; S2: adding 8 parts of dioctyl itaconate, 7.5 parts of glycidyl acrylate and 2 parts of vinyl pyrrolidone, after passing nitrogen protection, heating to 80-85°C, adding 0.5 parts of benzoyl peroxide and keeping warm for 6.5h; S3: after the reaction is completed, pour into 300 parts of icy ethanol for precipitation, filter and wash with deionized water 33 times, vacuum dry at 70°C for 10h, and then crush to a particle size of 60μm.

[0086] Other embodiments are the same.

[0087] Comparative Example 6

[0088] The difference between Comparative Example 6 and Example 1 is that the biodegradable resin, in parts by mass, specifically includes the following steps: S1: adding 65 parts of polybutylene succinate to 200 parts of tetrahydrofuran, stirring at 120 rpm at 70°C for 2h; S2: adding 20 parts of dioctyl itaconate, 7.5 parts of glycidyl acrylate and 1.5 parts of vinyl pyrrolidone, after passing nitrogen protection, heating to 80-85°C, adding 3.5 parts of benzoyl peroxide and keeping warm for 6.5h; S3: after the reaction is completed, pour into 300 parts of ice ethanol for precipitation, filter and wash with deionized water 33 times, vacuum dry at 70°C for 10h, and then crush to a particle size of 60μm.

[0089] Other embodiments are the same.

[0090] Performance Testing

[0091] 1. Mechanical Properties: Tested according to ASTM D638-14, the crystal mud was injection molded into a Type V dumbbell-shaped specimen (thickness 2±0.1mm, gauge length 25mm). The specimen was equilibrated at 23±2°C and 50±5% humidity for 24 hours at a tensile speed of 50 mm / min. The elongation at break was obtained by taking the average of 10 tests and recording them in Table 1.

[0092] 2. Degradability: The crystal mud was crushed to a particle size of 5 mm, dried to constant weight, and mixed with mature compost at a dry weight ratio of 1:6. The temperature was 56-60°C, the humidity was 50-55%, and the ventilation volume was 0.2 L / min·kg to ensure aerobic conditions. The degradation rate of the crystal mud was obtained after 180 days. The results were recorded in Table 1 as the average value of 10 tests.

[0093] 3. Plasticity: The test refers to ASTM D395-18. The crystal mud is made into a cylinder with a diameter of 25mm and a thickness of 12mm. The compression deformation rate is 50% and the compression time is 24 hours (23±2℃). After releasing the pressure, it recovers for 30 minutes to obtain the permanent deformation rate. The results are recorded in Table 1 by taking the average value of 10 tests.

[0094] 4. Storage stability: The storage conditions are temperature: 40±2℃, humidity: 75±5%, duration: 90 days. If there is no obvious change in appearance, it is qualified. Then test the elongation retention rate before and after the test. The results are the average of 10 tests and recorded in Table 1.

[0095] Table 1 Performance test results

[0096]

[0097] From the final test results shown in Table 1, it can be seen that Comparative Examples 1 and 2 did not use an appropriate amount of degradable resin and compound bio-based cross-linking, resulting in a significant decline in the overall performance of the crystal mud.

[0098] However, in Comparative Examples 3 to 6, since the correctly formulated bio-based cross-linking agent and degradable resin were not used, the synergistic effect of the system showed obvious deviations, which in turn led to a decrease in the overall performance.

Claims

1. A degradable crystal mud, characterized by: The raw materials include at least 40 to 55 parts of polyvinyl alcohol, 15 to 25 parts of degradable resin and 5 to 10 parts of compounded bio-based cross-linking agent in parts by mass; The preparation method of the biodegradable resin comprises: S1: adding polybutylene succinate to an organic solvent, heating and stirring to dissolve; S2: adding dioctyl itaconate, glycidyl acrylate and vinyl pyrrolidone, passing nitrogen for protection, and then adding benzoyl peroxide to keep warm for reaction; S3: pouring the product into ice ethanol for precipitation, filtering, washing, drying and crushing to obtain the product; The mass ratio of the polybutylene succinate, dioctyl itaconate, glycidyl acrylate and vinyl pyrrolidone is (70-85): (8-12): (6-10): (5-9).

2. The degradable crystal mud according to claim 1, characterized in that: The polymerization degree of the polyvinyl alcohol is 1600-1900, and the alcoholysis degree is 80-90%.

3. The degradable crystal mud according to claim 2, characterized in that: The compounded bio-based cross-linking agent is a composition of castor oil-based polyester polyol, tannic acid and chitosan quaternary ammonium salt, with a mass ratio of (5-7): (3-4): (1-3).

4. The degradable crystal mud according to claim 3, characterized in that: The mass ratio of the polyvinyl alcohol, the degradable resin and the compounded bio-based cross-linking agent is (45-55): (18-25): (6-9).

5. The degradable crystal mud according to claim 1, characterized in that: The raw materials of the degradable crystal mud, calculated by mass, also include: 1 to 3 parts of pH regulator, 8 to 15 parts of softener, 10 to 18 parts of plasticizer, 3 to 6 parts of degradation accelerator, 2 to 5 parts of moisturizer, 0.1 to 0.3 parts of preservative, 1 to 2.5 parts of color paste, 2 to 4 parts of powder, and 150 to 250 parts of deionized water.

6. The degradable crystal mud according to claim 5, characterized in that: The mass ratio of the polyvinyl alcohol, the softener and the plasticizer is (45-55): (10-13): (11-16).

7. The biodegradable crystal mud according to claim 6, characterized in that: The softener is a composition of hydrogenated rosin glycerol ester and epoxidized soybean oil, with a mass ratio of (5-9): (1-3).

8. The degradable crystal mud according to claim 7, characterized in that: The degradation accelerator is at least one of polyhydroxybutyrate, sodium lignin sulfonate, microcrystalline cellulose and sodium alginate.

9. A method for preparing the degradable crystal mud according to claim 5, characterized in that: The specific steps include: S1: Add polyvinyl alcohol to deionized water, heat in a water bath at 85-90°C, stir at 120-150 rpm for 1.5-2 hours, then cool to 70-75°C, add a degradable resin softener and a plasticizer, and stir at 180-200 rpm for 30-40 minutes; S2: Add a compounded bio-based cross-linking agent, keep warm at 65-70°C for 1-1.5 hours, then add a degradation accelerator, a moisturizer and a preservative, and stir at 50-55°C and 100-120 rpm for 30-40 minutes until uniform; S3: Add color paste and powder, stir at 120-150 rpm at 40-50°C for 20-30 minutes, and finally add a pH adjuster and stir to adjust the pH of the system to 6.5-7.

5.

10. Use of the degradable crystal mud according to claim 1 in stationery.

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