Biodegradable gelatin-glycerol sponge capable of lasting buffering

Abstract

The invention relates to the technical field of packaging material preparation, and discloses a biodegradable gelatin-glycerin sponge capable of lasting buffering and a preparation method thereof, in the process, the mechanical performance of the sponge is adjusted by adjusting the proportion of gelatin and glycerin, and the substance proportion under the excellent mechanical performance is determined. The gelatin is melted according to the proportion and then mixed with glycerin and water according to a certain mass ratio to prepare a gelatin-glycerin solution, and the gelatin-glycerin solution is foamed, frozen and dried to obtain the gelatin-glycerin sponge. The prepared gelatin-glycerol sponge has repeated buffering durability and fatigue resistance, has plasticity of being prepared into any required shape, and meanwhile, has the degradable performance of rapid degradation on the soil surface and in the soil; and on the basis of replacing the traditional white pollutants EPE and EPS, the composite material has the advantages of greenness and environmental protection, and has a wide application prospect in the field of packaging and buffering.

Description

Technical Field

[0001] This invention relates to the field of packaging material preparation technology, specifically to a biodegradable and durable cushioning gelatin-glycerin sponge. Background Technology

[0002] The statements in this section provide only background information relevant to the disclosure of this application and may not constitute prior art.

[0003] Cushioning materials are indispensable in logistics, product packaging, and the protection of precision instruments. Their core function is to protect items by effectively dissipating kinetic energy upon impact, and to maintain structural integrity and functionality under repeated impacts, i.e., possessing good fatigue resistance. For a long time, the market has been dominated by petroleum-based polymer foams, with Expandable Polystyrene (EPS) and Expanded Polyethylene (EPE) holding the majority of the market share due to their excellent cushioning performance and low production costs. These materials absorb energy through the plastic deformation of their cellular structure, performing well in single-impact protection. However, these materials are a significant contributor to "white pollution" (plastic pollution). With the pursuit of green production and low carbon emissions, the development of biodegradable green cushioning materials has become an important research direction for both academia and industry.

[0004] Therefore, research has shifted its focus to natural and renewable bio-based systems such as starch and cellulose. Numerous studies have been dedicated to developing various biodegradable buffer materials. For example, some studies have reported on sisal fiber-starch filled composite materials, demonstrating their degradation ability over a specific period; others have synthesized thick-walled cellulose sponges using temperature-controlled methods, which can also be largely degraded after being buried in soil for a certain period.

[0005] There is a pervasive and irreconcilable contradiction between environmental friendliness and durable cushioning performance. Materials designed for rapid degradation may have shorter molecular chains or lower cross-linking, further deteriorating their mechanical properties. Cushioning materials must withstand multiple drops and vibrations during transport; for early bio-based materials, each load-unload cycle accumulates minute, irreversible structural damage. For example, partially damaged pore walls can no longer effectively bear stress in subsequent cycles, leading to a decrease in the compressive stress plateau and reduced effective energy absorption capacity. Excellent materials should maintain largely consistent stress-strain curves after multiple cycles, but early bio-based materials often show significant changes in curve shape after only a few cycles, indicating that their fatigue resistance is far from meeting practical application requirements. Attempting to improve strength by enhancing cross-linking may reduce the degradation rate or make degradation conditions more demanding. Therefore, these materials are often only suitable for short-term, one-time applications with low cushioning requirements, and cannot serve as reliable alternatives to traditional foam plastics that require long-term durability and multiple uses, greatly limiting their application scope and market competitiveness.

[0006] Therefore, developing a biomass packaging material that simultaneously possesses good biodegradability and good fatigue resistance is a technical challenge for the industry. Summary of the Invention

[0007] The purpose of this invention is to address the current problem of the difficulty in simultaneously achieving biodegradability and fatigue resistance in biomass materials, and to provide a biodegradable gelatin-glycerol sponge that can provide long-lasting cushioning. The prepared gelatin-glycerol sponge can not only complete degradation in soil within 30 days, but also has good plasticity, maintains stable mechanical protective properties in complex humid and hot environments, and has excellent fatigue resistance; at the same time, it also has recyclability.

[0008] The technical solution of the present invention is as follows: This invention provides a method for preparing a biodegradable and durable cushioning gelatin-glycerin sponge, comprising the following steps: Step S1: In a water bath above the melting point of gelatin, add the gelatin, glycerin and water in the formula mass ratio. After the gelatin melts, stir evenly to obtain a gelatin-glycerin solution. Step S2: After foaming the gelatin-glycerol solution in an ice-water bath, transfer it to a mold and freeze it at -70~-30℃ for 12~36h. After freeze-drying for 36~64h, you will get a gelatin-glycerol sponge.

[0009] According to a preferred embodiment, in step S2, foaming specifically involves mechanically foaming the gelatin-glycerin solution or manually foaming it for about 30 minutes.

[0010] According to a preferred embodiment, the mechanical foaming is performed by stirring at 1000~2000 r / min for 5~10 min.

[0011] According to a preferred embodiment, in step S1, the mass ratio of gelatin, glycerin and water is 5:1:45 to 5:16:45.

[0012] In another aspect, the present invention provides a gelatin-glycerol sponge prepared using the method described above for preparing a biodegradable and durable cushioning gelatin-glycerol sponge.

[0013] Another aspect of the present invention provides a biodegradable and durable cushioning gelatin-glycerin sponge, which is made of gelatin, glycerin and water in a mass ratio of 5:1:45 to 5:16:45.

[0014] According to a preferred embodiment, when the gelatin-glycerol sponge is subjected to axial compression, its strain-stress curve shows a monotonically increasing trend and does not have an S-shaped inflection point, wherein the resilience of the material is not less than 90%; and the compression set of the material under constant compression for 30 minutes and 50% strain is not greater than 2.5%.

[0015] According to a preferred embodiment, the water vapor transmission rate of the gelatin-glycerol sponge 160% GGS at 23 °C is 0.8 × 10⁻⁶. 3 gm -2 d -1 The water vapor transmission rate at 38 ℃ is 3.5 × 10⁻⁶. 3 gm -2 d -1 .

[0016] According to a preferred embodiment, the maximum load of the gelatin-glycerin sponge is 5~15 N.

[0017] Another aspect of the present invention provides the application of the biodegradable gelatin-glycerin sponge as described above in the preparation of transport cushioning packaging materials.

[0018] Compared with existing technologies, the advantages of this invention are: 1. A biodegradable and durable cushioning gelatin-glycerin sponge, which is formulated by adding an appropriate amount of glycerin to gelatin and experimentally optimizing the amount of glycerin added; this improves the flexibility and extensibility of the gelatin foam, giving the gelatin-glycerin foam good mechanical properties, as well as excellent thermal stability and antifreeze properties. 2. A method for preparing a biodegradable and durable cushioning gelatin-glycerol sponge. By optimizing key parameters such as foaming temperature, freezing rate and drying procedure, a simple, short-cycle and scalable synthesis route was finally determined. The method is simple to operate, the raw materials are readily available, and the prepared gelatin-glycerol sponge has strong structural plasticity and excellent performance, which significantly expands the range of applications. 3. Application of a biodegradable and durable cushioning gelatin-glycerin sponge: The gelatin-glycerin sponge of this application has excellent mechanical properties and fatigue resistance, and is suitable for use in conventional cushioning packaging materials to replace traditional EPS and EPE materials. It meets the requirements of green and low-carbon environmental protection, and can be reused after use through rapid degradation in soil or secondary reconstruction by recycling. Attached Figure Description

[0019] Figure 1 (a) shows the synthesis flow chart of 160% GGS; (b) shows 160% GGS in different shapes. Figure 2 Compression cycle curves for 0%GGS (a) and 160%GGS (b), macroscopic comparison of resilience between 0%GGS and 160%GGS (c), comparison of resilience between 0%GGS and 320%GGS (d), comparison of maximum stress during compression cycles between 0%GGS and 320%GGS (e), and comparison of permanent deformation during compression between 80%GGS and 320%GGS (f). Figure 3 Figure 1 shows the water vapor transmission rate of 160% GGS at different temperature environments. Figure 4 (a) Comparison of resilience between EPE, EPS and 160% GGS; (b) Comparison of compression set between EPE, EPS and 160% GGS; (c) 50 compression cycle curve of 160% GGS; Figure 5 Comparison of the drop cushioning performance of EPE, EPS and 160% GGS eggs; Figure 6 Comparison of soil surface degradation of EPE, EPS and 160% GGS within 30 days (a) and soil burial degradation (b); Figure 7 Experiments were conducted to reconstitute 160% GGS. Detailed Implementation

[0020] The specific embodiments listed in this invention are merely examples, and the invention is not limited to the specific embodiments described below. For those skilled in the art, any equivalent modifications and substitutions to the embodiments described below are also within the scope of this invention. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of this invention should be covered within its scope. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are commercially available conventional products. To better illustrate this invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this invention can be practiced even without certain specific details. In other embodiments, methods, means, equipment, and steps well known to those skilled in the art are not described in detail in order to highlight the main points of this invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art. Unless otherwise specified, all units used in this specification are International Standard Units (SI), and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors unavoidable in industrial production.

[0022] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0023] Example 1 A method for preparing a biodegradable gelatin-glycerin sponge includes the following steps: like Figure 1 As shown in a, step S1: In a 70 ℃ water bath, add gelatin, glycerin and water in a mass ratio of 1:0:9~5:16:45, stir for 30 min until completely melted and homogeneous to obtain a gelatin-glycerin solution; adjust the mass ratio of gelatin to glycerin to 1:0, 5:1, 5:2, 5:3, 5:4, 5:5, 5:6, 5:7, 5:8, 5:9, 5:10, 5:12, 5:14 and 5:16 respectively; name them 0%GGS-320%GGS respectively.

[0024] Step S2: Place the gelatin-glycerol solution in a 0 ℃ ice water bath for foaming, then foam at 1500 r / min for 5 min to form a stable foam slurry; inject the foam into a custom mold, pre-freeze at -50 ℃ for 24 h to set ice crystals, and then freeze-dry for 48 h to sublimate and dehydrate to obtain 160% GGS with a regular appearance.

[0025] like Figure 1As shown in b, we used a mold method to prepare regular square and cylindrical samples, and they can also be manually cut into star shapes and other complex contours. Throughout the process, the sample edges remained intact and the surface was smooth, fully demonstrating the excellent plasticity of GGS and laying the foundation for functional applications.

[0026] Meanwhile, to determine the optimal ratio of gelatin to glycerol, 14 groups of samples with concentrations ranging from 0% to 320% were tested for static mechanical properties using a universal testing machine. Three compression cycles were performed at 50% strain, and the maximum stress and rebound rate were recorded. Taking the compression cycle curves of 0% GGS (a) and 160% GGS (b) as examples, it can be seen that the addition of glycerol significantly improves the mechanical properties of the material. The macroscopic rebound comparison experiment also visually demonstrates this. Figure 2 c) 160% GGS quickly returns to its original shape after being pressed, while 0% GGS shows obvious cracks. Comparison of resilience ( Figure 2 d) After three cycles of compression, 0% GGS-60% GGS could not achieve 100% resilience, while 80% GGS-320% exhibited 100% resilience during brief compression. The maximum stress of 14 groups of GGS ( Figure 2 e) The material exhibits a trend of first decreasing and then increasing, indicating that as the glycerol content increases, the material's texture changes from hard to soft and then back to hard, reaching its softest point at 160% GGS. This means that the rebound force on the protected item is minimized during cushioning, protecting the item while preventing secondary damage from material rebound. Based on the resilience test, we tested the compression set of 80% GGS-320% GGS. Figure 2 f) The results show that 120%-200% GGS exhibits better resistance to compressive settling, indicating that these GGS materials can maintain structural stability even under prolonged repeated loading conditions. Based on several tests, we determined 160% GGS to be the optimal mix ratio and will be the focus of future research.

[0027] The water vapor transmission rate (WVTR) of the 160% GGS prepared in Example 1 was tested (GB / T 1037-2021 cup method). The results showed that the 160% GGS material has open and interconnected microchannels inside, which endows the material with good moisture permeability. Figure 3 Data shows that at 23 ℃ and 38 ℃, the WVTR of 160% GGS is 0.8 × 10⁻⁶. 3 gm -2 d -1 and 3.5×10 3 gm -2 d -1(Approximately 30% of the blank control group). This result indicates that the material is not a completely sealed barrier layer, but rather possesses certain breathability. This open, moisture-permeable function not only inhibits the accumulation of condensate inside the packaging due to temperature differences, mitigating the risk of corrosion of electronic components, but also maintains the dryness of the framework through moisture removal, ensuring that the material maintains stable mechanical protective properties in complex humid and hot environments.

[0028] To verify whether 160% GGS has the potential to replace commercial petroleum-based foam, we selected EPE (expanded polyethylene) and EPS (expanded polystyrene), the most common materials used in e-commerce packaging, as references. We conducted compression cycle tests on resilience (GB / T14745-2017), permanent deformation (GB / T6669-2008), and multiple fatigue tests to comprehensively compare the mechanical properties of the three materials. In the compression cycle test at 50% strain, the resilience and compression set of the three materials showed significant differences. Figure 4 (a, 4b) 160% GGS exhibited a 100% springback rate after compression at 50% strain, while EPE and EPS only achieved 83% and 58%, respectively. After 30 minutes of constant compression (50% strain), 160% GGS showed almost no deformation, with compression set significantly lower than EPE (13%) and EPS (37%). This result confirms the reversible reconstruction capability of the gelatin-glycerol dynamic hydrogen bond network in GGS, which can rapidly recover its initial morphology after unloading external force, whereas the physical foaming nodes of EPE / EPS cannot recover after plastic deformation. To determine whether 160% GGS still possesses good mechanical properties after repeated and prolonged compression, we subjected 160% GGS to 50 consecutive compressions at 50% strain (… Figure 4 c), the results show that the stress-strain curves almost coincide and 160% GGS can still recover to its original state.

[0029] Figure 5 This study compares the cushioning performance of EPS, EPE, and 160% GGS under simulated transport impact conditions. Using an egg as a vulnerable model, the experiment systematically evaluates the protective capabilities of the three materials in practical cushioning applications. In drop tests, eggs were dropped freely from a fixed height of 45cm onto a hard surface and then onto the center of cushioning pads made of the three materials. The results showed that the eggs in the control group dropped onto the hard surface were broken, while the eggs in the 160% GGS, EPS, and EPE groups remained intact after five drops. This demonstrates that 160% GGS possesses the same excellent energy absorption and dispersion capabilities as EPS and EPE under instantaneous impact.

[0030] To assess the degradability and biosafety of 160% GGS in the natural environment, we conducted soil surface exposure and burial experiments simultaneously with EPE and EPS. Figure 6As shown, in the 30-day natural exposure experiment, the surfaces of EPS and EPE showed almost no significant changes, remaining intact until day 30 without cracks or mass loss. In contrast, 160% GGS exhibited obvious edge decomposition and transparency by day 5, and after 15 days, some surface areas had completely decomposed. By day 30, its macroscopic morphology had disappeared, and it was mixed with the surface soil after decomposition. In a further soil burial experiment, EPS and EPE maintained their original size and shape after 30 days at a depth of 5 cm, while 160% GGS softened significantly by day 5, lost its mechanical integrity within 10 days, and by day 30, it was barely visible to the naked eye, having become integrated with the soil. This highlights its ability to replace traditional petroleum-based foam, its rapid degradation in the natural environment, and its effective mitigation of the "white pollution" problem caused by traditional petroleum-based foam.

[0031] Based on the thermally reversible principle of physical cross-linked networks, we verified the recycling potential of GGS sponges. Figure 7 Through a low-energy heating and melting (70℃) / re-foaming process, waste sponges can be reshaped into brand-new products with no significant performance degradation.

[0032] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

Claims

1. A method for preparing a biodegradable and durable cushioning gelatin-glycerin sponge, characterized in that, Includes the following steps: Step S1: In a water bath above the melting point of gelatin, add the gelatin, glycerin and water in the formula mass ratio. After the gelatin melts, stir evenly to obtain a gelatin-glycerin solution. Step S2: After foaming the gelatin-glycerol solution in an ice-water bath, transfer it to a mold and freeze it at -70~-30℃ for 12~36h. After freeze-drying for 36~64h, you will get a gelatin-glycerol sponge.

2. The method for preparing a biodegradable and durable cushioning gelatin-glycerin sponge according to claim 1, characterized in that, In step S2, foaming specifically involves mechanically foaming the gelatin-glycerin solution.

3. The method for preparing a biodegradable and durable cushioning gelatin-glycerin sponge according to claim 2, characterized in that, The mechanical foaming is achieved by stirring at 1000~2000 r / min for 5~10 min.

4. The method for preparing a biodegradable and durable cushioning gelatin-glycerin sponge according to claim 1, characterized in that, In step S1, the mass ratio of gelatin, glycerin and water is 5:1:45 to 5:16:

45.

5. A gelatin-glycerol sponge prepared by the method for preparing a biodegradable and durable cushioning gelatin-glycerol sponge as described in any one of claims 1 to 4.

6. A biodegradable and durable cushioning gelatin-glycerin sponge, characterized in that, It is made from gelatin, glycerin and water in a mass ratio of 5:1:45 to 5:16:

45.

7. The biodegradable and durable cushioning gelatin-glycerin sponge according to claim 6, characterized in that, When subjected to axial compression, the strain-stress curve of the gelatin-glycerol sponge exhibits a monotonically increasing trend and does not have an S-shaped inflection point. The gelatin-glycerin sponge has a resilience of not less than 90%. The compression set of the gelatin-glycerol sponge under constant compression for 30 minutes and 50% strain is no greater than 2.5%.

8. The biodegradable and durable cushioning gelatin-glycerin sponge according to claim 6, characterized in that, The water vapor transmission rate of the gelatin-glycerol sponge (160% GGS) at 23 °C is 0.8 × 10⁻⁶. 3 gm -2 d -1 The water vapor transmission rate at 38 ℃ is 3.5 × 10⁻⁶. 3 gm -2 d -1 .

9. The biodegradable and durable cushioning gelatin-glycerin sponge according to claim 8, characterized in that, The maximum load of the gelatin-glycerin sponge is 5~15 N.

10. The use of a biodegradable and durable gelatin-glycerol sponge as described in claim 5 or any one of claims 6 to 9 in the preparation of transport cushioning packaging materials.

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