Biodegradable plant-based cold gel storage ice bag material and preparation method thereof

Abstract

The invention relates to a biodegradable plant-based cold gel storage ice bag material and a preparation method thereof. According to the cold gel storage ice bag material, synergistic modified plant-based macromolecules serve as a main body, a stable three-dimensional gel network is constructed through plant-based polysaccharide under the synergistic effect of an organic acid modifier and a polyhydroxy cross-linking activator, and proline is introduced to serve as an organic small molecule phase change regulating agent; the water-retaining agent is prepared by matching a polyhydric alcohol water-retaining agent, a natural inorganic gel reinforcing agent and a bio-based cross-linking auxiliary agent. The material can effectively adjust the phase change behavior of water molecules in a gel system, significantly prolong the cold release time, improve the freeze-thaw cycle stability and reduce the bleeding phenomenon. The biodegradable, safe and environment-friendly characteristics of the material are maintained, the cold storage performance and the structural stability are synchronously improved, and the material is suitable for the field of food, fresh food and medical cold chains.

Description

Technical Field

[0001] This invention relates to the field of functional polymer materials and cold chain storage materials, specifically to a biodegradable plant-based cold storage gel ice pack material and its preparation method. Background Technology

[0002] Gel ice packs are commonly used as a cooling medium in cold chain transportation and low-temperature preservation for cooling and maintaining the temperature of food, fresh produce, pharmaceuticals, and biological samples. However, existing gel ice pack materials are mostly composed of petrochemical-based polymers such as sodium polyacrylate, polyacrylamide, and polyvinyl alcohol. While these materials have certain water absorption and cooling capacity, they generally suffer from problems such as non-biodegradability, high environmental burden, and difficulty in waste disposal, which do not meet the current needs of green, low-carbon, and sustainable development.

[0003] Existing petrochemical-based or single-polymer gel systems are prone to structural damage during repeated freeze-thaw cycles, manifesting as gel network collapse, severe water separation, and decreased cold storage performance, resulting in shortened release time and failing to meet the requirements of long-term stable cold storage in cold chain transportation. To improve these issues, some technologies have attempted to introduce inorganic fillers or increase crosslinking density, but this often comes at the cost of flexibility, safety, or biodegradability, and it is difficult to effectively control the phase change behavior of water.

[0004] Plant-based polymer materials have gradually attracted attention due to their wide availability, renewability, and biodegradability. However, existing plant-based gel ice pack materials often suffer from defects such as low gel strength, insufficient freeze-thaw cycle stability, and limited cold storage efficiency. In particular, they lack precise means to regulate the phase change process of water molecules inside the gel, making it difficult for them to replace traditional petrochemical-based ice pack materials in practical applications.

[0005] Therefore, there is an urgent need to develop a novel gel ice pack material that can significantly improve the stability of the gel structure and the performance of cold storage and release while maintaining the biodegradability of plant-based materials. Furthermore, it is necessary to use new technological approaches to regulate the phase change behavior of water molecules in order to meet the application requirements of the cold chain industry that emphasize both environmental protection and performance. Summary of the Invention

[0006] To overcome the problems of insufficient gel strength, poor freeze-thaw stability, and limited cold storage and release performance of plant-based gel ice pack materials in the aforementioned background technologies, the present invention aims to provide a biodegradable plant-based cold storage gel ice pack material and its preparation method. The present invention utilizes synergistically modified plant-based polymers as the main gel framework, introduces proline as an organic small-molecule phase transition regulator, and combines it with polyol water-retaining agents, natural inorganic gel reinforcing agents, and bio-based crosslinking aids to construct a stable three-dimensional gel network structure, thereby achieving effective regulation of the phase transition behavior of water molecules in the gel system. The present invention significantly improves the cold storage efficiency, cold release time, and freeze-thaw cycle stability of gel ice packs while maintaining the biodegradability of the material.

[0007] The objective of this invention can be achieved through the following technical solutions: A biodegradable plant-based cold storage gel ice pack material comprises the following raw materials in parts by weight: 60-85 parts of synergistically modified plant-based polymer; 1-8 parts of organic small molecule phase change regulator; 5-15 parts of polyol water-retaining agent; 1-5 parts of natural inorganic gel reinforcing agent; 0.1-1.5 parts of bio-based crosslinking aid; and 100-200 parts of deionized water. The synergistically modified plant-based polymer is formed by synergistic modification of plant-based polysaccharides with organic acid modifiers and polyhydroxy crosslinking activators to construct a stable three-dimensional gel network structure. The organic small molecule phase change regulator is proline, which regulates the phase change behavior of the gel system by adjusting the hydrogen bond structure between water molecules, thereby improving cold storage efficiency and extending the cold release time.

[0008] Optionally, the synergistically modified plant-based polymer comprises the following raw materials in parts by weight: 70-95 parts sodium carboxymethyl starch; 1-5 parts citric acid; and 0.5-3 parts glycerol.

[0009] Optionally, the preparation method of the synergistically modified plant-based polymer includes the following steps: (1) Drying sodium carboxymethyl starch; (2) Add the dried sodium carboxymethyl starch to deionized water and stir to disperse, thus obtaining a polysaccharide dispersion system; (3) Citric acid was added to the polysaccharide dispersion system to carry out a synergistic modification reaction, resulting in a modified system; (4) Glycerol was added to the modified system for synergistic treatment to obtain synergistically modified plant-based polymers; (5) Cool, degas and seal the synergistic modified plant-based polymer.

[0010] Optionally, the drying conditions in step (1) are drying at 60-80℃ for 2-6 hours; the stirring and dispersing conditions in step (2) are stirring at 40-70℃ for 20-60 minutes; and the synergistic modification reaction conditions in step (3) are stirring at 50-80℃ for 30-120 minutes.

[0011] Optionally, the synergistic treatment conditions in step (4) are stirring and mixing at 50-80°C for 20-60 minutes; the degassing conditions in step (5) are standing at room temperature for 10-60 minutes.

[0012] Optionally, the polyol water-retaining agent is a mixture of glycerol and sorbitol in a mass ratio of (1-4):(1-3); the natural inorganic gel reinforcing agent is a mixture of attapulgite and montmorillonite in a mass ratio of (1-3):(1-2); and the bio-based crosslinking aid is a mixture of phytic acid and gluconolactone in a mass ratio of (1-5):(1-4).

[0013] Optionally, a method for preparing a biodegradable plant-based cold storage gel ice pack material, characterized in that the preparation method includes the following steps: S1, sodium carboxymethyl starch was dried and then added to deionized water and stirred to disperse, thus obtaining a polysaccharide dispersion system; S2, citric acid was added to the polysaccharide dispersion system to carry out a synergistic modification reaction, followed by the addition of glycerol for synergistic treatment, to obtain a synergistically modified plant-based polymer system; S3 involves mixing a synergistically modified plant-based polymer system with polyol water-retaining agents and natural inorganic gel enhancers to form a uniform gel precursor system, and then adding proline, an organic small molecule phase transition regulator, to it. S4. A bio-based crosslinking agent is added to the gel precursor system for crosslinking and curing treatment. After cooling and degassing, the mixture is filled and sealed to obtain a biodegradable plant-based cold storage gel ice pack material.

[0014] Optionally, the drying conditions in step S1 are drying at 60-80℃ for 2-6 hours and stirring and dispersing conditions are stirring at 40-70℃ for 20-60 minutes; the synergistic modification reaction conditions in step S2 are stirring and reacting at 50-80℃ for 30-120 minutes, and the synergistic effect treatment conditions are stirring and mixing at 50-80℃ for 20-60 minutes.

[0015] Optionally, the mixing conditions in step S3 are stirring at 30–60°C for 20–60 min to ensure that the polyol water-retaining agent, the natural inorganic gel enhancer, and proline are uniformly dispersed in the system; the crosslinking and curing conditions in step S4 are standing or slowly stirring at 25–50°C for 30–180 min, and the degassing conditions are standing at room temperature for 10–60 min to degas.

[0016] The beneficial effects of this invention are: This invention introduces proline as an organic small molecule phase change regulator into a plant-based cold storage gel system. This changes the traditional approach of relying on increasing crosslinking density or inorganic filler reinforcement to improve the cold storage performance of plant-based gel materials. It transforms the crystallization behavior of water molecules inside the gel from rapid and disordered crystallization to a restricted and delayed phase change process. As a result, the gel network structure can be maintained under repeated freeze-thaw conditions. This effectively overcomes the technical defects of existing plant-based gel ice packs, such as short release time, easy water separation after freeze-thaw, and rapid decay of cold storage performance. It achieves a long-term stable cold storage effect that is difficult to achieve in the prior art. Attached Figure Description

[0017] The invention will now be further described with reference to the accompanying drawings.

[0018] Figure 1 Comparison of infrared spectra of sodium carboxymethyl starch and synergistically modified plant-based polymers; Figure 2 A comparison chart of cooling time and water separation rate for samples with different ratios; Figure 3 A comparison chart showing the performance retention rate and morphology retention rate of samples with different ratios after freeze-thaw cycles. Detailed Implementation

[0019] The present invention will be further described below with reference to specific embodiments. However, the present invention is not limited to the following embodiments. Equivalent adjustments made without departing from the spirit and essence of the present invention should also be considered to fall within the protection scope of the present invention.

[0020] Example 1

[0021] This embodiment aims to verify the feasibility of the plant-based cold storage gel ice pack material system and the stability of the gel system formation when the dosage of each component and the reaction conditions are all within the recommended lower limit range.

[0022] Preparation process S1, Preparation of synergistically modified plant-based polymer systems: Take 70 parts of sodium carboxymethyl starch and dry it at 60℃ for 2 hours; add the dried sodium carboxymethyl starch to 100 parts of deionized water and stir and disperse at 40℃ for 20 minutes to obtain a polysaccharide dispersion system; add 1 part of citric acid to the polysaccharide dispersion system and stir and react at 50℃ for 30 minutes; then add 0.5 parts of glycerol and continue to stir and mix at 50℃ for 20 minutes to obtain a synergistically modified plant-based polymer system. S2, Construction of the gel precursor system: Add 5 parts of a polyol water-retaining agent obtained by mixing glycerol and sorbitol in a mass ratio of 1:1, and 1 part of a natural inorganic gel enhancer obtained by mixing attapulgite and montmorillonite in a mass ratio of 1:1 to the above-mentioned synergistically modified plant-based polymer system, and stir at 30°C for 20 min to form a uniform gel precursor system. S3, Introduction of phase change regulator: Add 1 part proline to the gel precursor system and continue stirring at 30°C for 20 min to ensure uniform dispersion; S4, Crosslinking Curing and Molding: Add 0.1 part of a bio-based crosslinking agent obtained by mixing phytic acid and gluconolactone in a mass ratio of 1:1 to the system, and allow it to crosslink at 25°C for 30 min; then allow it to stand at room temperature for 10 min to degas, fill and seal to obtain plant-based cold storage gel ice pack material.

[0023] Example 2

[0024] This embodiment aims to verify the structural stability of the synergistically modified plant-based polymer system and the overall applicability of the final gel ice pack material when the proportions of each component and the reaction conditions are within the recommended intermediate range.

[0025] Preparation process S1, Preparation of synergistically modified plant-based polymer systems: Take 82 parts of sodium carboxymethyl starch and dry it at 70℃ for 4 hours; add it to 150 parts of deionized water and stir and disperse at 55℃ for 40 minutes to obtain a polysaccharide dispersion system; add 3 parts of citric acid to this system and stir and react at 65℃ for 60 minutes; then add 1.5 parts of glycerol and continue stirring and mixing at 65℃ for 40 minutes to obtain a synergistically modified plant-based polymer system; according to Figure 1 The infrared spectrum comparison shows that the unmodified sample at 3400 cm⁻¹... -1 The peak at 1605 cm⁻¹ exhibits a broad and strong –OH stretching vibration, reflecting the strong hydrogen bonding between polysaccharide molecules; -1 With 1420cm -1 Carboxymethyl –COO can be observed at this location. - The characteristic absorption peaks indicate that the basic structure of sodium carboxymethyl starch remains intact; in the modified sample, the –OH absorption peak further broadens and shifts slightly to lower wavenumbers, indicating that the hydrogen bond network is enhanced after the introduction of citric acid and glycerol; simultaneously, at approximately 1735 cm⁻¹... -1 A new ester group C=O absorption peak appears at 1245 cm⁻¹, accompanied by a peak at 1245 cm⁻¹. -1 The enhanced C–O–C absorption in the vicinity indicates that esterification or synergistic cross-linking has occurred; the above changes confirm that the synergistic modification has successfully constructed a more stable plant-based polymer network structure. S2, Construction of the gel precursor system: Ten parts of a polyol water-retaining agent obtained by mixing glycerol and sorbitol in a mass ratio of 2:1, and three parts of a natural inorganic gel enhancer obtained by mixing attapulgite and montmorillonite in a mass ratio of 2:1 were added to the synergistically modified plant-based polymer system. The mixture was stirred at 45°C for 40 min to form a stable gel precursor system. S3, Introduction of phase change regulator: Add 4 parts of proline to the gel precursor system and stir at 45°C for 40 min to fully embed it into the gel system; S4, Crosslinking Curing and Molding: Add 0.8 parts of a bio-based crosslinking agent obtained by mixing phytic acid and gluconolactone in a mass ratio of 3:2 to the system, and slowly stir and crosslink at 40°C for 90 min; then let stand at room temperature for 30 min to degas, fill and seal to obtain plant-based cold storage gel ice pack material.

[0026] Example 3

[0027] This embodiment aims to verify the feasibility of the preparation method and the formation of the gel system under conditions of high cross-linking and high additives when the dosage of each component and the reaction conditions are all within the recommended upper limit.

[0028] Preparation process S1, Preparation of synergistically modified plant-based polymer systems: Take 95 parts of sodium carboxymethyl starch and dry it at 80℃ for 6 hours; add it to 200 parts of deionized water and stir and disperse at 70℃ for 60 minutes to obtain a polysaccharide dispersion system; add 5 parts of citric acid to the system and stir and react at 80℃ for 120 minutes; then add 3 parts of glycerol and continue to stir and mix at 80℃ for 60 minutes to obtain a synergistically modified plant-based polymer system. S2, Construction of the gel precursor system: Add 15 parts of a polyol water-retaining agent obtained by mixing glycerol and sorbitol in a mass ratio of 4:3, and 5 parts of a natural inorganic gel enhancer obtained by mixing attapulgite and montmorillonite in a mass ratio of 3:2 to a synergistically modified plant-based polymer system, and stir at 60°C for 60 min to form a gel precursor system. S3, Introduction of phase change regulator: Add 8 parts of proline to the gel precursor system and stir at 60℃ for 60 min to disperse it evenly. S4, Crosslinking Curing and Molding: Add 1.5 parts of a bio-based crosslinking agent obtained by mixing phytic acid and gluconolactone in a mass ratio of 5:4 to the system, and allow it to stand or stir slowly at 50°C for 180 min for crosslinking; then allow it to stand at room temperature for 60 min to degas, fill and seal to obtain plant-based cold storage gel ice pack material.

[0029] Comparative Example 1: This comparative example aims to verify the effect of using only citric acid, an organic acid modifier, for single modification of the synergistic modified plant-based polymer system without the synergistic effect of glycerol on the formation of the synergistic modified plant-based polymer system and the stability of the final gel ice pack material.

[0030] Preparation process S1, Preparation of synergistically modified plant-based polymer systems: Take 82 parts of sodium carboxymethyl starch and dry it at 70℃ for 4 hours; add it to 150 parts of deionized water and stir and disperse at 55℃ for 40 minutes to obtain a polysaccharide dispersion system; add 3 parts of citric acid to the system and stir and react at 65℃ for 60 minutes to obtain a single modified plant-based polymer system. S2, Construction of the gel precursor system: Ten parts of a polyol water-retaining agent obtained by mixing glycerol and sorbitol in a mass ratio of 2:1, and three parts of a natural inorganic gel enhancer obtained by mixing attapulgite and montmorillonite in a mass ratio of 2:1 were added to the above-mentioned single modified plant-based polymer system. The mixture was stirred at 45°C for 40 min to form a stable gel precursor system. S3, Introduction of phase change regulator: Add 4 parts of proline to the gel precursor system and stir at 45°C for 40 min to fully embed it into the gel system; S4, Crosslinking Curing and Molding: Add 0.8 parts of a bio-based crosslinking agent obtained by mixing phytic acid and gluconolactone in a mass ratio of 3:2 to the system, and slowly stir and crosslink at 40°C for 90 min; then let stand at room temperature for 30 min to degas, fill and seal to obtain plant-based cold storage gel ice pack material.

[0031] Comparative Example 2: This comparative example aims to verify the impact of using only the polyhydroxy crosslinking activator glycerol for the sole function of the synergistic modified plant-based polymer system, without the synergistic modification of citric acid, on the formation of the synergistic modified plant-based polymer system and the overall applicability of the final gel ice pack material.

[0032] Preparation process S1, Preparation of synergistically modified plant-based polymer systems: Take 82 parts of sodium carboxymethyl starch and dry it at 70℃ for 4 hours; add it to 150 parts of deionized water and stir and disperse at 55℃ for 40 minutes to obtain a polysaccharide dispersion system; add 1.5 parts of glycerol to the polysaccharide dispersion system and stir and mix at 65℃ for 40 minutes to obtain a single modified plant-based polymer system. S2, Construction of the gel precursor system: Ten parts of a polyol water-retaining agent obtained by mixing glycerol and sorbitol in a mass ratio of 2:1, and three parts of a natural inorganic gel enhancer obtained by mixing attapulgite and montmorillonite in a mass ratio of 2:1 were added to the above-mentioned single modified plant-based polymer system. The mixture was stirred at 45°C for 40 min to form a stable gel precursor system. S3, Introduction of phase change regulator: Add 4 parts of proline to the gel precursor system and stir at 45°C for 40 min to fully embed it into the gel system; S4, Crosslinking Curing and Molding: Add 0.8 parts of a bio-based crosslinking agent obtained by mixing phytic acid and gluconolactone in a mass ratio of 3:2 to the system, and slowly stir and crosslink at 40°C for 90 min; then let stand at room temperature for 30 min to degas, fill and seal to obtain plant-based cold storage gel ice pack material.

[0033] Comparative Example 3: This comparative example aims to verify the effect of not introducing the organic small molecule phase change regulator proline into the gel system on the phase change regulation capability and freeze-thaw stability / cooling performance of the gel system.

[0034] Preparation process S1, Preparation of synergistically modified plant-based polymer systems: Take 82 parts of sodium carboxymethyl starch and dry it at 70℃ for 4 hours; add it to 150 parts of deionized water and stir and disperse at 55℃ for 40 minutes to obtain a polysaccharide dispersion system; add 3 parts of citric acid to the system and stir and react at 65℃ for 60 minutes; then add 1.5 parts of glycerol and continue to stir and mix at 65℃ for 40 minutes to obtain a synergistically modified plant-based polymer system. S2, Construction of the gel precursor system: Ten parts of a polyol water-retaining agent obtained by mixing glycerol and sorbitol in a mass ratio of 2:1, and three parts of a natural inorganic gel enhancer obtained by mixing attapulgite and montmorillonite in a mass ratio of 2:1 were added to the synergistically modified plant-based polymer system. The mixture was stirred at 45°C for 40 min to form a stable gel precursor system. S3, Introduction of phase change regulator: In step S3, proline is not added, and the mixture is stirred at 45°C for 40 minutes to make the system homogeneous. S4, Crosslinking Curing and Molding: Add 0.8 parts of a bio-based crosslinking agent obtained by mixing phytic acid and gluconolactone in a mass ratio of 3:2 to the system, and slowly stir and crosslink at 40°C for 90 min; then let stand at room temperature for 30 min to degas, fill and seal to obtain plant-based cold storage gel ice pack material.

[0035] Performance testing: 1. Test methods for cold storage and release performance The plant-based cold storage gel ice packs prepared in Examples 1, 2, and 3, as well as Comparative Examples 1-3, were pretreated under the same conditions and uniformly frozen in a −18°C environment until the internal temperature stabilized. Subsequently, all samples were simultaneously removed and subjected to natural cold release tests under the same ambient temperature and air circulation conditions. A temperature monitoring point was set at the center of the ice pack, and the temperature changes of each sample during the cold release process were continuously recorded. The duration of different samples within the same temperature range was compared to evaluate the differences in cold storage efficiency and cold release duration among the examples and comparative examples.

[0036] 2. Freeze-thaw cycle stability test method The gel ice packs prepared in Examples 1, 2, and 3, as well as Comparative Examples 1-3, were subjected to multiple freeze-thaw cycles. Each freeze-thaw cycle included two stages: complete freezing at −18°C and complete thawing at room temperature. After completing the same number of freeze-thaw cycles, the appearance of each sample was observed, with particular attention paid to whether obvious water separation, loose gel structure, local collapse, or increased fluidity occurred, in order to evaluate the impact of different modification methods and the introduction of small organic molecules on the freeze-thaw cycle stability of the gel system.

[0037] 3. Water separation performance test method After completing the specified number of freeze-thaw cycles, the samples from Examples 1, 2, and 3, as well as Comparative Examples 1-3, were placed at room temperature for a certain period of time. Then, the outer bags were opened, and the water separation of the gel system was observed. By comparing the degree of free water generation on the surface of each sample, the uniformity of water separation, and the overall integrity of the gel, the effects of the synergistically modified plant-based polymer system and the organic small-molecule phase change regulator on the water retention performance of the gel were evaluated.

[0038] 4. Test methods for the morphology retention performance of gel systems The gel ice packs prepared in Examples 1, 2, and 3, as well as Comparative Examples 1-3, were subjected to freeze-thaw cycles under the same conditions, and their overall gel morphology was compared and observed. The focus was on whether each sample could maintain its original gel morphology before and after treatment, and whether obvious softening, delamination, cracking, or structural collapse occurred, in order to evaluate the influence of different component ratios and modification methods on the morphology retention performance of the gel system.

[0039] Table 1 Performance Test Results Sample number Cooling time (h) Performance retention rate after freeze-thaw cycles (%) Water separation rate (%) Shape retention rate (%) Example 1 6.8 88 6.5 91 Example 2 8.5 96 2.1 98 Example 3 7.6 92 3.8 95 Comparative Example 1 4.9 63 14.6 72 Comparative Example 2 5.2 67 13.2 75 Comparative Example 3 5.6 74 9.8 82 As shown in Table 1, there are significant differences among the different embodiments and comparative examples in terms of cooling time, freeze-thaw cycle stability, water separation rate, and gel morphology retention performance. Among them, Example 2 exhibits the best performance in all indicators, while Examples 1 and 3, although slightly inferior to Example 2, show significantly better overall performance than the comparative examples, demonstrating the overall advantages of the technical solution of this invention.

[0040] In terms of cold storage and cold release performance, Figure 2 The cooling times of Examples 1, 2, and 3 were 6.8 h, 8.5 h, and 7.6 h, respectively, all of which were significantly higher than the 4.9 to 5.6 h of Comparative Examples 1 to 3. Among them, Example 2 had the longest cooling time, indicating that under the medium ratio conditions, the synergistic effect of the synergistic modified plant-based polymer system and the organic small molecule phase change regulator was the most sufficient.

[0041] Regarding freeze-thaw cycle stability Figure 3 The performance retention rates after freeze-thaw cycles of Examples 1, 2, and 3 were 88%, 96%, and 92%, respectively, which were significantly higher than those of Comparative Example 1 (63%), Comparative Example 2 (67%), and Comparative Example 3 (74%). This indicates that the single modification or absence of the organic small molecule phase change regulator will weaken the stability of the gel structure during repeated freeze-thaw cycles, while the synergistic modification system of the present invention can effectively maintain the integrity of the gel network structure.

[0042] In terms of water separation performance, Figure 2 The water separation rates of Examples 1, 2 and 3 were 6.5%, 2.1% and 3.8% respectively, which were significantly lower than those of Comparative Examples 1 to 3 (9.8% to 14.6%). Among them, Example 2 had the lowest water separation rate, indicating that it had the strongest binding ability for water molecules, which was beneficial to suppressing the precipitation of free water during the freeze-thaw process.

[0043] Regarding gel morphology retention performance Figure 3 The morphological retention rates of Examples 1, 2 and 3 after freeze-thaw cycles were 91%, 98% and 95%, respectively, which were significantly better than the 72% to 82% of Comparative Examples 1 to 3, further demonstrating that the gel system constructed in this invention can still maintain good structural integrity under multiple freeze-thaw conditions.

[0044] In summary, Examples 1-3 of the present invention are generally superior to the comparative examples in terms of various performance indicators. Among them, Example 2 shows the most outstanding performance in terms of cold release duration, freeze-thaw cycle stability and structure retention ability, which fully demonstrates that the combination of synergistic modified plant-based polymer system and organic small molecule phase change regulator is the key to achieving the technical effect of the present invention.

Claims

1. A biodegradable plant-based cold storage gel ice pack material, characterized in that, The plant-based cold storage gel ice pack material comprises the following raw materials in parts by weight: 60-85 parts of synergistically modified plant-based polymer; 1-8 parts of organic small molecule phase change regulator; 5-15 parts of polyol water-retaining agent; 1-5 parts of natural inorganic gel reinforcing agent; 0.1-1.5 parts of bio-based cross-linking aid; and 100-200 parts of deionized water. The synergistically modified plant-based polymer is formed by the synergistic modification of plant-based polysaccharides by organic acid modifiers and polyhydroxy cross-linking activators. The organic small molecule phase change regulator is proline, which regulates the phase change behavior of the gel system by adjusting the hydrogen bond structure between water molecules.

2. The biodegradable plant-based cold storage gel ice pack material according to claim 1, characterized in that, The synergistically modified plant-based polymer comprises the following raw materials in parts by weight: 70-95 parts sodium carboxymethyl starch; 1-5 parts citric acid; and 0.5-3 parts glycerol.

3. A biodegradable plant-based cold storage gel ice pack material according to claim 1 or 2, characterized in that, The preparation method of the synergistically modified plant-based polymer includes the following steps: (1) Drying sodium carboxymethyl starch; (2) Add the dried sodium carboxymethyl starch to deionized water and stir to disperse, thus obtaining a polysaccharide dispersion system; (3) Citric acid was added to the polysaccharide dispersion system to carry out a synergistic modification reaction, resulting in a modified system; (4) Glycerol was added to the modified system for synergistic treatment to obtain synergistically modified plant-based polymers; (5) Cool, degas and seal the synergistic modified plant-based polymer.

4. The biodegradable plant-based cold storage gel ice pack material according to claim 3, characterized in that, The drying conditions in step (1) are 60-80℃ for 2-6 hours; the stirring and dispersing conditions in step (2) are 40-70℃ for 20-60 minutes; and the synergistic modification reaction conditions in step (3) are 50-80℃ for 30-120 minutes.

5. The biodegradable plant-based cold storage gel ice pack material according to claim 3, characterized in that, The synergistic treatment conditions for step (4) are stirring and mixing at 50-80℃ for 20-60 minutes; the degassing conditions for step (5) are standing at room temperature for 10-60 minutes.

6. The biodegradable plant-based cold storage gel ice pack material according to claim 1, characterized in that, The polyol water-retaining agent is a mixture of glycerol and sorbitol in a mass ratio of (1-4):(1-3); the natural inorganic gel reinforcing agent is a mixture of attapulgite and montmorillonite in a mass ratio of (1-3):(1-2); and the bio-based crosslinking aid is a mixture of phytic acid and gluconolactone in a mass ratio of (1-5):(1-4).

7. A method for preparing a biodegradable plant-based cold storage gel ice pack material, characterized in that, The preparation method includes the following steps: S1, sodium carboxymethyl starch was dried and then added to deionized water and stirred to disperse, thus obtaining a polysaccharide dispersion system; S2, citric acid was added to the polysaccharide dispersion system to carry out a synergistic modification reaction, followed by the addition of glycerol for synergistic treatment, to obtain a synergistically modified plant-based polymer system; S3 involves mixing a synergistically modified plant-based polymer system with polyol water-retaining agents and natural inorganic gel enhancers to form a uniform gel precursor system, and then adding proline, an organic small molecule phase transition regulator, to it. S4. A bio-based crosslinking agent is added to the gel precursor system for crosslinking and curing treatment. After cooling and degassing, the mixture is filled and sealed to obtain a biodegradable plant-based cold storage gel ice pack material.

8. The method for preparing a biodegradable plant-based cold storage gel ice pack material according to claim 7, characterized in that, The drying conditions for step S1 are drying at 60-80℃ for 2-6 hours and stirring and dispersing conditions are stirring at 40-70℃ for 20-60 minutes; the synergistic modification reaction conditions for step S2 are stirring and reacting at 50-80℃ for 30-120 minutes and the synergistic effect treatment conditions are stirring and mixing at 50-80℃ for 20-60 minutes.

9. The method for preparing a biodegradable plant-based cold storage gel ice pack material according to claim 7, characterized in that, The mixing conditions in step S3 are stirring at 30-60°C for 20-60 minutes to ensure that the polyol water-retaining agent, natural inorganic gel enhancer and proline are uniformly dispersed in the system; the crosslinking and curing conditions in step S4 are standing or slowly stirring at 25-50°C for 30-180 minutes, and the degassing conditions are standing at room temperature for 10-60 minutes to degas.

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