A kind of PBAT bio-based modified material and mould pressing high magnification PBAT bio-based foamed material

Abstract

This invention relates to the field of bio-based polymer materials and their foaming materials, specifically disclosing a PBAT bio-based modified material and a high-ratio molded PBAT bio-based foaming material. The toughening agent in the modified PBAT formulation is an ethylene-maleic anhydride copolymer, and may further include EVA and additives. The high-ratio molded PBAT bio-based foaming material includes a main material and additives. The main material includes the aforementioned PBAT bio-based modified material, and also includes one or more of EVA, POE, and EPDM rubber. By modifying existing PBAT bio-based materials, the defects of existing bio-based foaming materials, such as high density, poor physical properties, and poor processing performance, can be overcome. When applied to foaming material production, this foaming material can be produced using a chemical foaming molding process, achieving a high ratio of over 200% foaming. The resulting products possess comprehensive advantages such as low density, high rigidity and toughness, excellent rebound and shock absorption performance, good dimensional stability, clear surface patterns, and controllable biodegradability potential.

Description

Technical Field

[0001] This invention relates to the field of bio-based polymer materials and their foaming materials. Background Technology

[0002] With increasing global environmental awareness, the demand for bio-based and biodegradable materials in many fields, especially in the fast-moving consumer goods (FMCG) sector such as footwear and packaging, is becoming increasingly urgent. Currently, most environmentally friendly footwear materials on the market achieve their eco-friendly concept by adding organic biodegradable fillers such as corn starch, coffee grounds, sugarcane bagasse, tea stalks, and malt stalks. However, these materials generally have the following drawbacks: First, to maintain a certain structural strength, the amount of biomass filler added is often large, resulting in high density and weight in the final product, making it difficult to achieve lightweight design; second, the material's overall physical properties are poor, especially its tear strength and tensile strength, making the soles prone to damage and breakage during wear, resulting in insufficient durability; third, the product's appearance is rough, making it difficult to meet the refinement requirements of mid-to-high-end products.

[0003] PBAT (polybutylene terephthalate) is a thermoplastic biodegradable plastic that has attracted attention due to its good flexibility, ductility, and biodegradability. The ester bonds in its molecular chain can undergo hydrolysis and breakage under specific environmental conditions (such as humidity, heat, and microbial activity), ultimately decomposing into carbon dioxide and water, aligning with environmental trends. However, unmodified PBAT, as a typical chemically inert material, has a regular molecular chain and few active reaction sites, making it difficult to crosslink in conventional chemical foaming systems. This hinders the preparation of high-ratio, high-property foamed products through chemical foaming processes such as molding. In existing technologies, the application of PBAT bio-based materials mostly employs physical foaming processes, but these suffer from problems such as unstable properties, large dimensional shrinkage, easy deformation after heating (e.g., UV irradiation, oven heating), and poor surface pattern retention, severely limiting its application in products requiring fine appearance and stable performance, such as shoe soles.

[0004] Furthermore, the industry still lacks effective technical solutions for achieving high-ratio (e.g., exceeding 200%) foaming of high-PBAT bio-based foam materials while maintaining excellent overall physical properties such as rigidity, toughness, resilience, and fatigue resistance, and preserving controllable biodegradability. Therefore, developing a PBAT-based foam material suitable for compression molding chemical foaming processes that combines high ratio, lightweight, high physical properties, and controllable degradation characteristics has significant market value and technical importance. Summary of the Invention

[0005] The purpose of this invention is to provide a PBAT bio-based modified material to overcome the shortcomings of existing bio-based foamed materials, such as high density, poor physical properties, and poor processing performance.

[0006] Another objective of this invention is to provide a high-ratio PBAT bio-based foaming material with the above-mentioned modified material as the main component. This foaming material adopts a chemical foaming molding process, which can achieve a high ratio of over 200% foaming. The resulting product has comprehensive advantages such as low density, high rigidity and toughness, excellent rebound and shock absorption performance, good dimensional stability, clear surface pattern, and controllable biodegradation potential.

[0007] A PBAT bio-based modified material, wherein the modified PBAT formulation includes EVA, a toughening agent and an additive, wherein the toughening agent is anhydrous ethylene-maleic anhydride copolymer.

[0008] Furthermore, the modified formulation material also includes additives. The raw materials of the modified formulation material include, by weight, 40-85 parts of PBAT, 15-60 parts of EVA, 0.5-3 parts of ethylene-maleic anhydride copolymer, and 0.5-3 parts of additives.

[0009] Preferably, the raw materials for the modified formulation include, by weight, 65-75 parts PBAT, 25-35 parts EVA, 0.5-2 parts anhydrous maleic anhydride, and 0.5-2 parts additives.

[0010] More preferably, the raw materials for the modified formulation include, by weight, 70 parts PBAT, 30 parts EVA, 1.5 parts ethylene-maleic anhydride copolymer, and 1 part additives.

[0011] Furthermore, the VA content of the EVA is 28%, and / or the ethylene-maleic anhydride copolymer is produced by Vantrus Corporation of the United States, with the model number Zemac E60P.

[0012] Furthermore, the PBAT is baked before modification treatment at a temperature of 90-100℃ for 2-3.5 hours.

[0013] A high-ratio molded PBAT bio-based foam material, the raw materials of which include a main material and additives, wherein the main material includes the PBAT bio-based modified material as described above.

[0014] Furthermore, the main material also includes one or more of EVA, POE, and EPDM rubber; the VA content of the EVA is 26%; and the foaming ratio of the initial preform is controlled at 200-208% during production.

[0015] Furthermore, the main materials, by weight, include: 50-70 parts of PBAT bio-based modified material, 12-30 parts of EVA, 15-25 parts of POE, and 2-5 parts of EPDM rubber; the additives, by weight, include: 1.2-2.2 parts of filler, 8-10 parts of wear-resistant agent, 0.4-0.5 parts of stearic acid, 0.7-0.8 parts of zinc stearate, 1.4-1.6 parts of zinc oxide, 2-4 parts of titanium dioxide, 0.6-0.65 parts of crosslinking agent, and 5.5-6.0 parts of high-temperature foaming agent.

[0016] Preferably, the main materials, by weight, include: 60 parts of PBAT bio-based modified material, 15 parts of EVA with 26% VA content, 22 parts of POE with POE8003, and 3 parts of EPDM rubber; the additives, by weight, include: 1.5 parts of filler, 9 parts of wear-resistant agent, 0.45 parts of stearic acid, 0.75 parts of zinc stearate, 1.49 parts of zinc oxide, 3 parts of titanium dioxide, 0.62 parts of crosslinking agent, and 5.8 parts of high-temperature foaming agent.

[0017] By adopting the above technical solution, the beneficial effects of the present invention are as follows: The above-mentioned PBAT bio-based modified material achieves efficient graft modification of PBAT, particularly by using anhydrous ethylene-maleic anhydride copolymer for specific graft modification of PBAT. The ethylene-maleic anhydride copolymer is a long-chain polymer copolymer (molecular weight approximately 60,000 g / mol) formed by alternating ethylene and maleic anhydride in a strict 1:1 molar ratio. Each anhydride group on its molecular chain is interspersed with ethylene segments, resulting in a stable structure and moderate reactivity. When introducing active reactive sites onto the PBAT molecular chain, the ethylene-maleic anhydride copolymer possesses the following unique advantages:

[0018] 1. High reaction efficiency and stability: Ordinary maleic anhydride is prone to self-polymerization at high temperatures, resulting in low grafting efficiency. In contrast, ethylene-maleic anhydride copolymers can be stably grafted, with controllable reactions and high grafting rates. Furthermore, as a prepolymer, the ethylene-maleic anhydride copolymer exhibits a mild reaction, significantly reducing PBAT degradation at high temperatures and maintaining a high molecular weight.

[0019] 2. Strong interfacial bonding: The long molecular chains of ethylene-maleic anhydride copolymer can effectively entangle the interface between the two phases in the blend system, forming a strong "molecular anchoring" effect. Compared with short-chain branching agents, the interfacial bonding is stronger, thereby improving the tensile strength and elongation at break of the material.

[0020] 3. Avoid foaming defects: High molecular weight ethylene-maleic anhydride copolymer can form physical anchor points inside the matrix, avoiding "pinholes" or bubble defects left after the migration and volatilization of small molecule additives, which helps to obtain a more uniform and dense cell structure.

[0021] 4. Significantly Improved Melt Strength: The ethylene-maleic anhydride copolymer effectively improves the melt strength of PBAT through branching or micro-crosslinking, enabling it to encapsulate the foaming agent and prevent bubble coalescence and collapse. This ensures stable foaming ratio and uniform cell size, laying the foundation for achieving high-ratio chemical foaming exceeding 200%. In contrast, conventional toughening agents or ordinary maleic anhydride are prone to degradation, resulting in excessively low melt strength and difficulty in forming high-ratio foam.

[0022] Good process stability: Ethylene-maleic anhydride (such as Zemac E60P produced by Vantrus Corporation, USA) is a granular solid, allowing for accurate metering and avoiding batch instability caused by metering drift; its reaction temperature range is relatively wide, preventing cross-linking due to local overheating, and making it easier to control in industrial production.

[0023] The grafting modification described above forms side chains and a network structure on the PBAT molecular chain, which not only significantly improves the reactivity of PBAT itself and its compatibility with other polymer materials, but also lays the foundation for the subsequent preparation of high-performance foam materials. This allows PBAT to effectively participate in the cross-linking reaction of chemical foaming systems, thus solving the problem of difficult cross-linking and foaming of inert PBAT materials. Furthermore, the grafted structure also acts as a "molecular reinforcing rib." Even if some ester bonds degrade and break under future environmental conditions, the surrounding grafted network structure can still maintain the overall strength of the material, achieving a balance between "controllable degradation" and "high physical properties."

[0024] The aforementioned high-ratio PBAT bio-based foaming material is based on modified PBAT bio-based materials and can be combined with materials such as EVA, POE, and EPDM rubber. Through optimized formulation design, the material system can achieve a high ratio of over 200% (e.g., 208% in this embodiment) during the compression molding chemical foaming process, with uniform foaming, smooth initial molding, no tearing, and no deformation. The density of the foamed material obtained in the experiment can be as low as 0.096 g / cm³, exhibiting significant lightweight advantages and achieving a balance between ultra-high ratio chemical foaming and excellent physical properties. The resulting foamed materials exhibit excellent comprehensive physical properties, with products possessing outstanding rigidity, toughness, and rebound shock absorption performance. For example, the foamed shoe sole with high PBAT bio-based modified material in the preferred technical solution provides excellent support and deformation resistance (resistant to wrinkling even after prolonged wear). The introduction of POE and EPDM contributes to good toughness, fatigue resistance, and low-temperature performance. Various physical properties (such as tensile strength, elongation at break, delamination tear strength, resilience, and compression set) meet or exceed the application requirements of high-end shoe sole materials. Furthermore, due to the good compatibility of PBAT bio-based modified materials with other components and uniform melt blending and dispersion, the use of a molding chemical foaming process results in high dimensional stability and low shrinkage (shrinkage rate can be less than 1% at 70℃*20min in experiments). The bottom and sidewall patterns are clear and full, with a refined appearance, overcoming the shortcomings of easily deformed and blurred patterns in physically foamed products. This demonstrates the excellent processing performance and appearance quality of the foamed materials. In addition, the foaming material is mainly composed of bio-based and biodegradable components (the content in the experiment is as high as 60%). While maintaining the performance during the service life, it gives the product the potential to eventually be biodegradable in specific waste environments, which is in line with the green and environmentally friendly sustainable development direction and has outstanding environmental significance. Detailed Implementation

[0025] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0026] This embodiment discloses a PBAT bio-based modified material. PBAT is a thermoplastic biodegradable plastic formed by copolymerization through transesterification. The modified PBAT material of this invention includes toughening agents, foaming materials, and additives. One improvement of this modified material is that the toughening agent is an anhydrous ethylene-maleic anhydride copolymer. In existing material modification processes, aqueous toughening agents are typically used, and some even have high moisture content requirements. To solve the problems of existing technologies and achieve the research and development objectives, this invention takes a different approach, abandoning conventional choices and selecting an anhydrous ethylene-maleic anhydride copolymer. As used in this embodiment, the ethylene-maleic anhydride copolymer is manufactured by Vantrus Corporation, USA, under the trade name ZemacE60P. Its chemical formula is (C4H2O3.C2H4)n or (C6H6O3)n. The typical molecular weight is approximately 60,000 g / mol. In the field of PBAT modification and foaming, using ethylene-maleic anhydride copolymer (E60P) has significant advantages over using ordinary maleic anhydride directly: the maleic anhydride groups of E60P can be stably grafted onto the PBAT molecular chain, the reaction is controllable, and the grafting rate is high; its long molecular chains can effectively entangle the two-phase interface, resulting in strong interfacial bonding; at the same time, it can significantly reduce the high-temperature degradation of PBAT and maintain a high molecular weight; furthermore, E60P is a granular solid, with stable metering, avoiding batch instability caused by metering drift, a wide reaction temperature range, and will not cross-link due to local overheating, resulting in good process control. This invention uses E60P as a toughening agent, which is moisture-free, avoiding the adverse effects of moisture on the foaming process. Its grafting efficiency is far higher than that of conventional water-containing toughening agents or ordinary maleic anhydride, exhibiting highly efficient and specific grafting modification effects in modification treatment. Thus, based on the physical property requirements of the applied products, the components can be matched and the production method adjusted to obtain a variety of modified materials with different physical property requirements.

[0027] The modified formulation also includes foaming materials and additives. PBAT and the foaming material are specifically grafted onto the ethylene-maleic anhydride copolymer, introducing active reaction sites into the PBAT molecular chain. The modified grafted material forms side chains and a network structure, significantly improving the reactivity of PBAT and its compatibility with other polymers. This lays the foundation for the subsequent preparation of high-performance foaming materials, enabling it to effectively participate in the cross-linking reaction of the chemical foaming system, thus achieving the aforementioned beneficial effects. This invention aims to further develop materials with properties similar to those required for shoe soles. The PBAT can be the existing thermoplastic elastomer PBAT-GPM5. The PBAT molecular chain contains flexible segments (BA) and rigid segments (BT), exhibiting excellent machinability, with typical properties including a melting point of 125-135 degrees Celsius. Furthermore, the additive is an anti-sticking agent, and stearic acid can be selected. In addition, in this embodiment, different foaming materials can be selected according to the performance requirements of the product to be manufactured. In this embodiment, considering the manufacture of shoe sole materials, EVA (ethylene / vinyl acetate) is preferred, especially EVA with a VA content of 28%, which can achieve an optimal balance between polarity, flexibility, compatibility and processability. The specific benefits are as follows: significantly enhanced polarity, improving adhesion; balance between softness and strength: 28% EVA provides high elasticity and flexibility while retaining good cohesive strength, which can both toughen the system without making it too soft when used for modification; broad compatibility, which can act as a "bridge" and provide better processing fluidity.

[0028] The following is a method for preparing a PBAT bio-based modified material disclosed in this embodiment: PBAT, EVA, ethylene-maleic anhydride copolymer (high-efficiency toughening agent), and anti-sticking agent (stearic acid) are premixed uniformly in a high-speed mixer in a certain proportion (it should be noted that in the technical solution of this invention, before the premixing process in the mixer, the PBAT material is baked in an oven under the following conditions: temperature around 100℃ (90-100℃), time around 3 hours (2-3.5 hours)). Then, melt blending and grafting reaction are carried out through a twin-screw extruder. The temperature of each section of the twin-screw extruder is set between 135-145℃ (for example, the twin-screw extruder has six sections, and the temperature settings of the six sections are: 135℃, 135℃, 140℃, 140℃, 145℃, 145℃). Under set parameters, the grafting reaction between PBAT molecular chains and ethylene-maleic anhydride copolymer is promoted by the twin-screw shearing action, which improves the dispersibility between the main material and the additives, and enhances the grafting performance of the material. This results in a PBAT bio-based modified material with a lower softening point, improved melt flowability, good grafting effect, and significantly improved crosslinking performance. The preceding baking treatment of the PBAT material in an oven is beneficial to the reaction in the process and the enhancement of these effects.

[0029] After research, development, trial production, and testing, the raw materials of the modified PBAT bio-based modified material formulation in this embodiment, within the following weight ratio range, demonstrate the intended effect of this invention and improve upon existing technical problems. Specifically, the formulation includes: 40-85 parts PBAT, 15-60 parts EVA, 0.5-3 parts ethylene-maleic anhydride copolymer, and 0.5-3 parts additives. In this embodiment, the PBAT used is the existing product PBAT-GPM5, the EVA used is an existing product with a VA content of 28%, and the additive is stearic acid, an anti-sticking agent. Different ratios of PBAT bio-based modified materials can be selected depending on the application product. For example, for applications such as shoe soles, automobiles, bags, furniture, and building materials, different ratios of modified materials can be chosen based on the varying requirements for product properties.

[0030] The table below (Table 1) shows the formulation ratios of several trial production tests that showed significant differences.

[0031] raw materials Group 1 (PHR) Group 2 (PHR) Group 3 (PHR) PBAT-GPM5 30 50 70 EVA (VA 28%) 70 50 30 Common toughening agents 0.5 -- -- Ethylene-maleic anhydride copolymer --- 0.8 1.5 stearic acid 1 1 1

[0032] The differences in the formulation ratios of the groups in Table 1 are as follows: Group 1 uses modified materials prepared with common toughening agents, while Groups 2 and 3 use ethylene-maleic anhydride copolymer as toughening agents. EVA and stearic acid are added to the materials of all three groups. The amount of PBAT in the three groups gradually increases, with the amount of ethylene-maleic anhydride copolymer in Group 3 increasing to 1.5 PHR.

[0033] Table 2 below shows the physical property test results of the trial products of the several trial formulations mentioned in Table 1.

[0034] Test Project Group 1 Group 2 Group 3 Asker c hardness 82 84 86 Specific gravity g / cm3 1.09 1.12 1.15 Melting temperature ℃ 120 124 125 Tensile strength MPa 14.6 17.9 18.6 Elongation at break % 678 705 752 Right-angle tear (KN / m) 122.5 128 134.7 Melt index (g / 10min) 5.2 4.5 3.5

[0035] Table 2 shows three groups of experimental formulations for modifying and grafting polyester PBAT materials. The physical property test results indicate that the physical properties of the second and third groups, using ethylene-maleic anhydride copolymer as the toughening agent, are improved compared to those using ordinary toughening agents. Furthermore, the physical properties gradually improve with increasing PBAT dosage. Regarding the compatibility and dispersion performance (samples) of the three groups, the first group exhibits some dispersibility, but the foamed sheet lacks rigidity and is prone to tearing. The second group shows better dispersibility than the first, with increased foamed sheet rigidity and less mold breakage and tearing. The third group not only exhibits good dispersibility and fine foam without small bubbles, but also good foamed sheet rigidity, good mold breakage resistance, and no tearing. These superior characteristics are attributed to the increased dosage of PBAT and ethylene-maleic anhydride copolymer. It is evident that the third formulation, consisting of 70 parts PBAT, 30 parts EVA, 1.5 parts ethylene-maleic anhydride copolymer, and 1 part additives, is the optimal technical solution. Even with a PBAT content as high as 70%, it still exhibits the highest hardness, strength, tear resistance, and optimal melt blending dispersion and foaming processing performance. After modification, the material softening point is reduced, the material fluidity and melt index are improved, and the handling performance is also better. It has good grafting effect and dispersion performance, the fineness of the foamed sheets is the best, and the physical properties are stable. This proves that the grafting modification effect of the technical solution provided by this invention is better.

[0036] The ethylene-maleic anhydride copolymer (E60P) used in this invention is not ordinary anhydrous maleic anhydride, and its mechanism of action is as follows:

[0037] 1. As a reactive compatibilizer and chain extender: The maleic anhydride groups in E60P are highly reactive and readily react with the hydroxyl groups (-OH) at the ends of the PBAT molecular chains to form branched or long-chain structures, thereby significantly improving the melt viscosity and strength of PBAT. After modification, the complex viscosity of PBAT can increase by approximately 3400 Pa·s, which is beneficial for forming a uniform and dense microporous structure.

[0038] 2. Improved melt strength and foaming performance: PBAT has a linear structure and low melt strength, making it prone to bubble breakage or collapse during processing. E60P effectively improves melt strength through branching or micro-crosslinking, ensuring that the foaming agent is well encapsulated and preventing bubble coalescence and collapse, thus providing a key guarantee for achieving high expansion ratios exceeding 200%.

[0039] 3. The advantages of E60P in PBAT modification compared to ordinary anhydrous maleic anhydride (molecular formula: C4H2O3) are as follows:

[0040] Reaction behavior It is prone to self-aggregation and has low grafting efficiency. The reaction is controllable and the grafting rate is high. Impact on matrix degradation It can easily cause molecular chain breakage and performance degradation. The reaction is mild, significantly reducing degradation and maintaining high molecular weight. Interface Combination Short bridging effect, bonding strength is generally low Long chain winding, strong interface bonding Foaming defects Small molecules are prone to migration and volatilization, forming pinholes. Polymer anchor points prevent pinholes and ensure uniform cell size. melt strength Easily degrades excessively, resulting in low melt strength. Branching / micro-crosslinking significantly improves melt strength. Process control Sensitive to temperature and prone to fluctuations Particulate solid, stable metering, wide temperature window

[0041] Therefore, using ethylene-maleic anhydride copolymer (E60P) can more efficiently achieve graft modification of PBAT, improving its processing stability and overall properties of the foamed product in the molding chemical foaming system. In summary, ethylene-maleic anhydride copolymer (E60P) follows a technical route of thickening, strengthening, and stabilizing, while ordinary (anhydrous) maleic anhydride is more prone to degradation, volatilization, and performance fluctuations. Therefore, using E60P can more efficiently achieve graft modification of PBAT, improving its processing stability and overall properties of the foamed product in the molding chemical foaming system. The modified treatment formulation of this invention, with a preferred range for application to similar shoe sole performance requirements, comprises the following raw materials by weight: 65-75 parts PBAT, 25-35 parts EVA, 0.5-2 parts ethylene-maleic anhydride copolymer, and 0.5-2 parts additives.

[0042] This invention discloses a high-ratio PBAT bio-based foam material for molding, particularly suitable as a shoe sole material. Its raw materials include main materials and additives. The main materials include the aforementioned PBAT bio-based modified material, and also include one or more of EVA, POE (polyolefin elastomer), and EPDM (ethylene propylene diene monomer). This embodiment uses EVA, POE, and EPDM simultaneously to produce a shoe sole foam material. The core material among these main materials is still the PBAT bio-based modified material. The combination of these materials further leverages the complementary properties of each, resulting in a foam material with superior overall performance. Specifically: EVA has moderate hardness and excellent overall properties, improving adhesion; POE (polyolefin elastomer) aids in delamination and tearing under high-ratio foaming conditions; EPDM significantly improves compression set and resilience; thus, the product exhibits better physical properties. The EVA used here, based on the physical properties of the foaming material, preferably has a VA content of 26% or 26%. The hardness is 3-5A harder than VA28%, ensuring the foamed material is not too soft, and the difference in elasticity and softness is minimal. For the POE, this embodiment preferably uses POE8003 or POE8150, especially POE8003. POE8003 is 10A harder than POE8150, which is beneficial for tensile strength. In terms of tear resistance, POE8003 is superior to POE8150. Particularly for high-ratio foaming materials, POE8003 has moderate hardness and good overall physical properties. The additives include fillers, abrasion resistant agents, stearic acid, zinc stearate, zinc oxide, titanium dioxide, crosslinking agents, and high-temperature foaming agents.

[0043] The following is a method for preparing a high-ratio PBAT bio-based foamed material for molding, as disclosed in this embodiment: First, the above-mentioned PBAT bio-based modified material is prepared, followed by the preparation of the foaming material base. The above-mentioned PBAT bio-based modified material, EVA, POE, EPDM, and additives are mixed in a ratio in an internal mixer or open mill, with the temperature controlled at 115-125℃, so that the components are fully melted and evenly dispersed to obtain a mixed base. Then, it is foamed and molded through molding (MD) process. The process includes the initial foaming stage and the subsequent molding stage: In this embodiment, the foaming ratio of the initial foam is controlled at over 200% (up to 208%) in the experimental formula; the subsequent molding stage is carried out in a mold, with a heating temperature of 175-180℃ and a hot pressing time of 450±30 seconds, followed by water cooling for about 500±30 seconds to obtain the final foamed product.

[0044] After research, development, trial production, and testing, the preferred formulation range for this embodiment of a high-ratio PBAT bio-based foaming material used in the manufacture of foamed shoe soles is as follows: the main materials, by weight, include: 50-70 parts PBAT bio-based modified material, 12-30 parts EVA, 15-25 parts POE, and 2-5 parts EPDM rubber; the additives, by weight, include: 1.2-2.2 parts filler, 8-10 parts abrasion resistant agent, 0.4-0.5 parts stearic acid, 0.7-0.8 parts zinc stearate, 1.4-1.6 parts zinc oxide, 2-4 parts titanium dioxide, 0.6-0.65 parts crosslinking agent, and 5.5-6.0 parts high-temperature foaming agent (AC-6000 can be used). In production applications, the PBAT bio-based modified material can account for approximately 40%-70% of the total weight of the raw materials.

[0045] The table below, Table 3, shows the formulation ratios of several experimental formulas used in the research and development pilot production trials.

[0046] raw materials Group 1 (PHR) Group 2 (PHR) Group 3 (PHR) PBAT bio-based modified materials 20 33 60 EVA (VA 26%) 50 38 15 POE8003 -- -- 22 POE8150 18 22 -- EPDM rubber 12 7 3 talcum powder 4.5 4.5 1.5 abrasion resistance 9 9 9 stearic acid 0.45 0.45 0.45 Zinc stearate 0.75 0.75 0.75 Zinc oxide 1.49 1.49 1.49 Titanium dioxide 3 3 3 Odorless bridging 0.6 0.6 0.62 High-temperature foaming agent AC 5.9 5.9 5.8

[0047] Table 4 below shows the physical property test results of several test formulations mentioned in Table 3 above.

[0048] Test Project Group 1 Group 2 Group 3 hardness shore A 40 41 42 Specific gravity g / cm3 0.100 0.098 0.096 Rebound rate % 62 65 66 Tensile strength MPa 2.0 2.2 2.4 Elongation at break % 316 359 378 Adhesive strength (N / cm) 22.8 27.5 30.9 Forefoot rebound performance (%) 62.3 63.8 66.5 Heel shock absorption performance 8.6 8.0 7.8 Aging resistance (grade) 4 4 4 Lightfastness Test, Method B (Grade) 4 4 4 Compression deformation % 42 40.6 38.5 Delamination tear N / cm 17.5 20.3 22.8 Abrasion resistance (mm) 11.8 11.6 11.2 Energy regression rate (%) 80.3 82.8 84.6 Shrinkage performance % (Test temperature: 70℃, Test time: 20 minutes) 1.1 0.9 0.75

[0049] Table 3 above shows several experimental formulations with different proportions of main materials. From group 1 to group 3, the content of PBAT bio-based modified material in the formulation increased (20%→60%). With the increase of PBAT bio-based modified material content, the comprehensive physical properties of the foamed material showed a significant improvement trend, especially in delamination tearing, tensile strength, and resilience. During the foaming process, due to the modification treatment of PBAT by combining it with EVA, ethylene-maleic anhydride copolymer, and other materials and processes, its softening point decreased, and its material fluidity and melt index increased, comparable to other main materials. It can be melted synchronously within the same time, achieving excellent dispersion performance, thus significantly improving the condensate properties. The initial preform ratio in the trial production stage was greater than 200% (reaching 208% in the trial production). The initial preform at a high ratio also had a large mold jumping force, without tearing or deformation, and with excellent flatness. The material is lightweight, rigid, tough, and exhibits excellent resilience and shock absorption performance. Although the molecular chains of PBAT bio-based modified materials have been grafted to form a large spatial network structure, if the amount added in the third experimental formulation is relatively large (60%), there are still some ester bonds in the molecular chains of its main adhesive. Under specific conditions, these bonds can be hydrolyzed and broken. The broken small molecules become microbial metabolic products, and some can be decomposed into carbon dioxide and water. Therefore, the finished product can achieve a certain degree of degradation under specific conditions.

[0050] The experimental formulation in Group 3 of Table 4 above achieved excellent values ​​in key indicators such as density (0.096 g / cm³), resilience (66%), tensile strength (2.4 MPa), elongation at break (378%), delamination tear (22.8 N / cm), and energy return rate (84.6%), and had the lowest shrinkage rate (0.75%), achieving a perfect combination of ultra-lightweight and high physical properties. Compared with some existing biomass filler (starch-based) environmentally friendly foamed shoe materials on the market (density is about 0.25-0.30 g / cm³, tensile strength is usually below 1.5 MPa, resilience is below 50%, and they are prone to breakage and deformation after wear), the foamed material in Group 3 has an overwhelming advantage in terms of lightweight density (reduced by more than 60%) and core mechanical properties and resilience performance. At the same time, its appearance and processing precision are also far superior to traditional biomass filler materials.

[0051] It is evident that the third experimental formulation within the optimized ratio range exhibits superior physical properties. With an initial preform ratio exceeding 200% (reaching as high as 208%, a leading level among known bio-based materials in compression molding and chemical foaming), the resulting products have a delicate feel, significant lightweight effect (approximately 30% weight reduction compared to traditional lightweight EVA foam materials), and excellent rigidity and toughness (resistant to wrinkles and deformation even after prolonged wear). Resilience and shock absorption properties complement each other, and the finished products exhibit clear patterns on the bottom and sidewalls, dimensional stability, and direct contact with the ground. In summary, the optimized ratio range demonstrates the best operational performance and optimal overall physicochemical properties, achieving the lightest and best-performing bio-based material currently known in the industry.

[0052] This invention successfully solves the industry problem of high-PBAT content materials being difficult to chemically foam and having poor physical properties by combining front-end ethylene-maleic anhydride copolymer graft modification with back-end optimized formulation. The resulting foamed material not only has excellent performance but also possesses environmentally friendly properties due to its high proportion of biodegradable PBAT.

[0053] The above embodiments are not intended to limit the product form and style of the present invention. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims

1. A PBAT bio-based modified material, characterized in that, The modified PBAT formulation includes EVA, toughening agent and additives, wherein the toughening agent is anhydrous ethylene-maleic anhydride copolymer.

2. The PBAT bio-based modified material as described in claim 1, characterized in that, The raw materials for the modified formulation include, by weight, 40-85 parts PBAT, 15-60 parts EVA, 0.5-3 parts ethylene-maleic anhydride copolymer, and 0.5-3 parts additives.

3. The PBAT bio-based modified material as described in claim 2, characterized in that, The raw materials for the modified formulation include, by weight, 65-75 parts PBAT, 25-35 parts EVA, 0.5-2 parts ethylene-maleic anhydride copolymer, and 0.5-2 parts additives.

4. The PBAT bio-based modified material as described in claim 3, characterized in that, The raw materials for the modified formulation include, by weight, 70 parts PBAT, 30 parts EVA, 1.5 parts ethylene-maleic anhydride copolymer, and 1 part additives.

5. A PBAT bio-based modified material as described in any one of claims 1-4, characterized in that, The EVA used has a VA content of 28%, and / or the ethylene-maleic anhydride copolymer is produced by Vantrus Corporation of the United States, with the model number Zemac E60P.

6. A PBAT bio-based modified material as described in any one of claims 1-4, characterized in that, The PBAT is baked before modification treatment at a temperature of 90-100℃ for 2-3.5 hours.

7. A high-ratio molded PBAT bio-based foam material, characterized in that: Its raw materials include main ingredients and additives, wherein the main ingredients include PBAT bio-based modified materials as described in any one of claims 1-6.

8. The high-ratio molded PBAT bio-based foam material of claim 7, characterized in that: The main materials also include one or more of EVA, POE, and EPDM rubber; the VA content of the EVA is 26%; and the foaming ratio of the initial preform is controlled at 200-208% during production.

9. A high-ratio molded PBAT bio-based foam material as described in claim 7 or 8, characterized in that: The main materials, by weight, include: 50-70 parts of PBAT bio-based modified material, 12-30 parts of EVA, 15-25 parts of POE, and 2-5 parts of EPDM rubber; the additives, by weight, include: 1.2-2.2 parts of filler, 8-10 parts of wear-resistant agent, 0.4-0.5 parts of stearic acid, 0.7-0.8 parts of zinc stearate, 1.4-1.6 parts of zinc oxide, 2-4 parts of titanium dioxide, 0.6-0.65 parts of crosslinking agent, and 5.5-6.0 parts of high-temperature foaming agent.

10. The high-ratio molded PBAT bio-based foam material of claim 9, characterized in that: The main materials, by weight, include: 60 parts of PBAT bio-based modified material, 15 parts of EVA with 26% VA content, 22 parts of POE with POE8003, and 3 parts of EPDM rubber; the additives, by weight, include: 1.5 parts of filler, 9 parts of wear-resistant agent, 0.45 parts of stearic acid, 0.75 parts of zinc stearate, 1.49 parts of zinc oxide, 3 parts of titanium dioxide, 0.62 parts of crosslinking agent, and 5.8 parts of high-temperature foaming agent.