Bio-based thermoplastic vulcanizates

Abstract

This invention provides a bio-based thermoplastic vulcanizate, belonging to the field of thermoplastic vulcanizate manufacturing. The invention employs a multifunctional compound grafting agent to graft a bio-based small-molecule plasticizer into polylactic acid (PLA) for single-phase plasticization, obtaining plasticized graft-modified PLA. The plasticized graft-modified PLA is then mixed with a bio-based random copolyester elastomer and a vulcanizing agent, followed by dynamic vulcanization to obtain the bio-based thermoplastic vulcanizate. The bio-based thermoplastic vulcanizate of this invention increases processability without losing, and may even increase, the mechanical strength of the rubber phase, achieving a balance between high mechanical properties and good processability. It also solves the problem of plasticizer migration.

Description

Technical Field

[0001] This invention relates to rubber production and manufacturing technology, and more particularly to a bio-based thermoplastic vulcanizate, belonging to the field of thermoplastic vulcanizate manufacturing technology. Background Technology

[0002] As the polymer materials industry continues to expand, the amount of its waste is also rising, making the effective disposal of these waste materials a growing concern. Currently, substitution and recycling are the two main solutions: on the one hand, biodegradable materials can be used to replace traditional polymer materials; on the other hand, resource recycling can be achieved through the recycling of waste materials. Compared to the former, recycling and reuse not only increases the added value of materials but also helps to build a carbon closed loop throughout the entire life cycle of materials.

[0003] Thermoplastic vulcanizates (TPVs) are unique rubber-plastic blends prepared through a "dynamic vulcanization" process. This process involves shearing and vulcanizing the rubber phase during melt blending, forming micron-sized cross-linked rubber particles dispersed within a continuous thermoplastic phase. TPVs combine the elasticity of traditional vulcanized rubber with the processability of thermoplastics, allowing for repeated processing and recycling. They have wide applications in the automotive, electronics, construction, and medical fields. Their recyclability and reprocessability fundamentally solve the recycling and reuse problems of traditional thermosetting rubbers, conserving petroleum resources and benefiting environmental protection. However, the waste generated by these TPVs with varying properties at the end of their service life creates significant environmental pressure, making TPV waste disposal a pressing issue.

[0004] Even though bio-based TPVs offer superior performance, their high rubber content typically results in high melt viscosity, leading to processing difficulties, high energy consumption, and long molding cycles. To address this issue, the industry's mainstream plasticizing method can be summarized as "integral plasticizing." This method involves adding plasticizers along with rubber, plastics, and other additives to the mixing equipment during the blending stage before dynamic vulcanization. In its high-temperature molten state, the plasticizer distributes throughout the blend system, simultaneously plasticizing both the rubber and plastic phases, thereby reducing the overall viscosity and hardness of the system and improving its flowability.

[0005] However, this traditional “holistic plasticization” method has a series of inherent defects and technical bottlenecks that are difficult to overcome.

[0006] First, the lack of selectivity in plasticizing leads to performance sacrifice. While the large amount of plasticizer entering the rubber phase reduces its viscosity, it also weakens the strength and elasticity of the rubber cross-linking network, resulting in decreased resilience and significantly reduced mechanical strength (such as tensile and tear strength) in the final product. Simultaneously, the limited plasticizing effect on the plastic phase further hinders the overall plasticizing outcome.

[0007] Secondly, the viscosity ratio between the two phases is difficult to precisely control, leading to uncontrolled rubber particle size and unstable performance. There is a risk of long-term plasticizer migration ("oil seepage" or "oil oozing"), affecting product lifespan and appearance. Furthermore, there is a lack of precise means to control rubber particle size.

[0008] Therefore, there is an urgent need in the existing technology for a new type of bio-based thermoplastic vulcanizate that can increase processing performance without losing or even increasing the mechanical strength of the rubber phase, achieving a balance between high mechanical properties and good processability, while also solving the problem of plasticizer migration. Summary of the Invention

[0009] This invention provides a novel bio-based thermoplastic vulcanizate, which utilizes a bifunctional grafting agent to graft a bio-based plasticizer into the plastic phase. By adjusting the viscosity ratio of the two phases through a gradient method to approach equal viscosity, it solves the technical problems of poor processing performance, low mechanical strength, and easy migration of plasticizers in existing thermoplastic vulcanizates.

[0010] The bio-based thermoplastic vulcanizate of this invention uses a multifunctional compound grafting agent to graft a bio-based small molecule plasticizer into polylactic acid (PLA) for single-phase plasticization to obtain plasticized graft-modified PLA. The plasticized graft-modified PLA is then mixed with a bio-based random copolyester elastomer and a vulcanizing agent and subjected to dynamic vulcanization to obtain the bio-based thermoplastic vulcanizate. The bio-based random copolyester elastomer is a copolymer of bio-based dicarboxylic acid, bio-based diol, and alkyd compound; the number-average molecular weight of the bio-based random copolyester elastomer is 5,000 to 80,000; and the number-average molecular weight of the polylactic acid is 20,000 to 250,000. The weight ratio of polylactic acid, bio-based small molecule plasticizer, and multifunctional compound grafting agent is 100:5-40:3-30; the weight ratio of bio-based random copolyester elastomer, vulcanizing agent, and plasticized grafted polylactic acid is 100:0.05-2:10-70. The bio-based thermoplastic vulcanizate described above, wherein the weight ratio of polylactic acid, bio-based small molecule plasticizer, and multifunctional compound grafting agent is 100:10-30:5-20.

[0011] The bio-based thermoplastic vulcanizate described above, wherein the weight ratio of the bio-based random copolyester elastomer, vulcanizing agent, and plasticized graft-modified polylactic acid is 100:0.1-1:22-55.

[0012] The bio-based thermoplastic vulcanizate as described above, wherein the number-average molecular weight of the bio-based random copolyester elastomer is 5000 to 20000; The vulcanizing agent is any one or a combination of dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butyl peroxide), and dicumyl peroxide. The polylactic acid has a number-average molecular weight of 100,000 to 150,000. The bio-based small molecule plasticizer is any one or a combination of acetylated tributyl citrate, tributyl citrate, triacetyl triacetate, polyethylene glycol, and itaconic acid esters.

[0013] The bio-based thermoplastic vulcanizate as described above, wherein the multifunctional compound grafting agent includes isocyanate multifunctional groups and multifunctional epoxy compounds; The isocyanate polyfunctional group is any one or a combination of diphenylmethane diisocyanate MDI, hexamethylene diisocyanate HDI, 4,4'-dicyclohexylmethane diisocyanate HMDI, toluene diisocyanate TDI, and L-lysine diisocyanate LDI. The multifunctional epoxy compound is any one or a combination of epoxidized soybean oil, epoxidized cottonseed oil, polyethylene glycol diglycidyl ether, 2,2'-diepoxy ethylene, and polyethylene glycol glycidyl dodecyl ether.

[0014] The bio-based thermoplastic vulcanizate described above, wherein the polylactic acid, bio-based small molecule plasticizer, and multifunctional plasticizer are prepared into plasticized graft-modified polylactic acid in an internal mixer; the melt blending temperature in the internal mixer is 170-210°C, and the rotation speed is 60-120 rpm; After mixing the plasticized grafted polylactic acid with bio-based random copolyester elastomer, a vulcanizing agent was added at room temperature and the mixture was placed in a mixer for dynamic vulcanization. In the bio-based thermoplastic vulcanizate described above, the melt blending temperature in the internal mixer is 175–200°C, and the rotation speed is 80–100 rpm.

[0015] The bio-based thermoplastic vulcanizate described above, wherein the plasticized graft-modified polylactic acid needs to be purified; During the purification process, the plasticized grafted polylactic acid needs to be dissolved in an organic solvent, then flocculated with an alcohol solvent and dried; the organic solvent is any one or a combination of dichloromethane, chloroform, tetrahydrofuran, acetone, ethyl acetate and dimethylformamide; the alcohol solvent is any one or a combination of methanol and ethanol.

[0016] The bio-based thermoplastic vulcanizate described above, wherein the dynamic vulcanization melting conditions in the internal mixer are maintained at a temperature of 150–200°C, a rotation speed of 60–120 rpm, and a time of 5–20 min; The bio-based thermoplastic vulcanizate described above, wherein the dynamic vulcanization melting conditions in the internal mixer are maintained at a temperature of 175–185°C, a rotation speed of 80–100 rpm, and a time of 5–10 min.

[0017] This invention employs a bifunctional linear short-linking grafting agent and grafted bio-based plasticizers such as butyl citrate, tributyl acetyl citrate, and glyceryl triacetate into the PLA mobile phase to reduce the viscosity of the mobile phase and adjust the viscosity ratio of the two phases to be close to isoviscosity. This results in better rubber particle breakage, improving processability without losing or even increasing the mechanical strength of the rubber phase, achieving a balance between high mechanical properties and good processability. It also solves the problem of plasticizer migration. Compared to the direct addition of plasticizers in existing technologies, this provides a new approach to the plasticizing strategy of TPV and the particle size control of rubber particles.

[0018] This invention plasticizes bio-based thermoplastic vulcanized rubber, effectively increasing its processing performance, reducing losses during processing, protecting equipment and saving energy, and reducing the decomposition of materials caused by strong shear during processing.

[0019] This invention fixes the directional distribution of plasticizers while plasticizing, effectively preventing the harmful effects of their migration. At the same time, the plasticizer fixed in the plastic phase can significantly reduce the viscosity of the plastic phase and adjust the viscosity ratio between the two phases, providing a new approach to studying the mechanism of the plasticizing process.

[0020] The plasticizing method provided by this invention is also applicable to research on plasticizing and particle size control of various other thermoplastic vulcanizates. Attached Figure Description

[0021] Figure 1 shows the performance characterization of the TBC-direct plasticized TPV products in Examples 1-5: ( Figure 1a (Fig. 1b) Tensile curves after plasticization; Air evaporation / solvent migration performance after plasticization, and migration performance indicators in Comparative Examples 1-9; Figure 2 Examples 5-10 ( Figure 2a The stretch curve of TPV after production, ( Figures 2b to 2d TPV's air evaporation / solvent migration properties; Figure 3 Comparison of appearance of unplasticized / Example 4 / Example 9 products; Figure 4. Tension curves of repeated processing in Examples 4 and 9 ( Figure 4a This is a stretching curve diagram of repeated processing in Example 4. Figure 4b (Example: Stretching curve of repeated processing in Example 9).

[0022] Origin / TPV - Raw Unplasticized Thermoplastic Vulcanizate TBC-Tributyl Citrate ATBC-acetylglucosyl tributyl ester GTA-triacetin ETOH-ethanol Petroleum ether H2O-water TPV / TBC-X: This refers to TPV plasticized by directly adding plasticizers, where X represents the number of parts of plasticizer added. BBTPV-X: A TPV prepared by grafting 30 parts of tributyl citrate onto PLA, where X represents the amount of grafting agent used in the PLA. Stress - Tensile Strength Strain - tensile strain Mass Loss Content of Plasticizer - Dosage Contents of PEGDE-Epoxy Grafting Agent Dosage Recycle-X-Times: Represents a sample that has been processed X times. Detailed Implementation

[0023] The testing instruments and conditions used in this embodiment are as follows: The gel content was measured using a Soxhlet extractor. 3g of each sample was placed on a 300-mesh copper grid and extracted using a circulating extraction method for 72 hours. Dichloromethane was chosen as the extraction solvent.

[0024] The mechanical properties of the composite material were tested according to ASTM D638 standard, using a CMT4104 universal electronic tensile testing machine. Samples with dimensions of 25×6×2mm³ (injection molded) were stretched at a speed of 50mm / min. At least five tensile specimens were tested for each sample, and the median value was taken as the final test result.

[0025] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0026] The raw materials used in the examples are as follows, all of which were purchased from Alfa Aesar: PLA—polylactic acid, with a number-average molecular weight of 103,200 and a molecular weight distribution of 2.11; TBC-Tributyl Citrate ATBC-acetylglucosyl tributyl ester GTA-triacetin ESO-Epoxidized Soybean Oil BBPE—a biodegradable polyester elastomer; TPV—Bio-based thermoplastic vulcanized rubber; MDI—diphenylmethane diisocyanate; PGE-polyethylene glycol diglycidyl ether Preparation of Examples and Comparative Examples Preparation of TPV: The bio-based TPV was prepared using the method described in Example 1 of patent CN114507424A. Bio-based polyester elastic was blended with polylactic acid at 170°C / 80 rpm, then cooled to 90°C and a crosslinking agent was added. The mixture was then heated again to 170°C / 80 rpm for dynamic vulcanization to obtain the TPV.

[0027] Preparation of BBPE: It was prepared using the preparation method of butene glycol-based polyester elastomer in Example 1 of patent CN113136027A.

[0028] The bio-based thermoplastic vulcanizate of this invention uses a multifunctional compound grafting agent to graft a bio-based small molecule plasticizer into polylactic acid (PLA) for single-phase plasticization to obtain plasticized graft-modified PLA. The plasticized graft-modified PLA is then mixed with a bio-based random copolyester elastomer and a vulcanizing agent and subjected to dynamic vulcanization to obtain the bio-based thermoplastic vulcanizate. The bio-based random copolyester elastomer is a copolymer of bio-based diacid, bio-based diol, and alkyd compound; the number-average molecular weight of the bio-based random copolyester elastomer is 5,000 to 80,000, preferably 5,000 to 20,000; the number-average molecular weight of the polylactic acid is 20,000 to 250,000, preferably 100,000 to 150,000. The weight ratio of polylactic acid, bio-based small molecule plasticizer, and multifunctional compound grafting agent is 100:5-40:3-30; preferably, the weight ratio is 100:10-30:5-20.

[0029] The weight ratio of the bio-based random copolyester elastomer, vulcanizing agent, and plasticized graft-modified polylactic acid is 100:0.05-2:10-70; preferably, the weight ratio is 100:0.1-1:22-55.

[0030] The vulcanizing agent is any one or a combination of dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butyl peroxide), and dicumyl peroxide. The bio-based small molecule plasticizer is any one or a combination of acetylated tributyl citrate, tributyl citrate, triacetyl triacetate, polyethylene glycol, and itaconic acid esters.

[0031] The polylactic acid, bio-based small molecule plasticizer, and multifunctional plasticizer are prepared into plasticized graft modified polylactic acid in an internal mixer; the melt blending temperature in the internal mixer is 170-210℃ and the rotation speed is 60-120 rpm; preferably, the temperature is 175-200℃ and the rotation speed is 80-100 rpm.

[0032] After mixing the plasticized grafted polylactic acid with bio-based random copolyester elastomer, a vulcanizing agent was added at room temperature and the mixture was placed in a mixer for dynamic vulcanization. The plasticized grafted polylactic acid (PLA) needs to be purified. During the purification process, the PLA is dissolved in an organic solvent, then flocculated with an alcohol solvent and dried. The organic solvent is any one or a combination of dichloromethane, chloroform, tetrahydrofuran, acetone, ethyl acetate, and dimethylformamide. The alcohol solvent is any one or a combination of methanol and ethanol.

[0033] The melting conditions for dynamic vulcanization in the internal mixer are maintained at a temperature of 150–200°C, a rotation speed of 60–120 rpm, and a time of 5–20 min; preferably, the temperature is 175–185°C, the rotation speed is 80–100 rpm, and the time is 5–10 min.

[0034] Preparation process of PLA-g-TBC PLA (per 100 parts) and varying amounts of TBC were added, and polyfunctional isocyanates or polyfunctional epoxy compounds were weighed according to the proportions in Table 1. After weighing, all three were placed in a 500 mL Erlenmeyer flask, and 300 mL of dichloromethane was added to dissolve them. The mixture was stirred at 200 rpm for 24 hours at room temperature. After stirring, the solution was transferred to a tetrafluoroethylene box to evaporate the solvent. After the surface solvent evaporated, the product was placed in a vacuum oven and dried at 60°C under vacuum for 6 hours. The product was then hot-pressed at 180°C for 10 minutes in a flat vulcanizing machine. The hot-pressed product was dissolved in dichloromethane at a concentration of 0.1 g / mL. After homogeneous dissolution, ethanol was added to flocculate and purify the solution. The resulting flocculated product was placed in a vacuum oven and dried at 60°C under vacuum for 6 hours to obtain the final product.

[0035] The specific preparation method of polylactic acid composite material is as follows: Using polylactic acid (PLA) matrix as 100 phr, PLA and bio-based biodegradable thermoplastic vulcanizate in the formulation ratios shown in Table 1 were melt-blended in a Haake internal mixer at 190°C and 80 rpm for 5 min. Then, a specific amount of PDLA-g-BBPE from the formulation was added, and the mixture was melt-blended again in the Haake internal mixer at 190°C and 80 rpm for another 5 min. Samples were then removed. Using a laboratory micro-injection molding machine at 190°C, the composite material was injection molded into dumbbell-shaped and rectangular impact specimens of the standard 25*6*2 mm³ size according to ASTM D638 for subsequent mechanical property testing.

[0036] Table 1. Ingredient ratios for the examples and comparative examples Based on the above method, a series of direct plasticized TPV and grafted modified TPV composite materials were prepared according to the proportions in Table 1, and the relevant properties are shown in Table 2. Table 2. Properties of the plasticized composite materials obtained in the examples and comparative examples Examples 1-5 show how the viscosity ratio of the two phases was adjusted to find the amount of plasticizer with similar viscosity. Based on this amount, the amount of grafting agent was adjusted to different amounts. Examples 6-10 show how different amounts were used to find the optimal ratio.

[0037] The results in Table 2 show that regardless of the type and amount of grafting agent, the addition of the third component to the plasticizer can promote a decrease in TPV hardness and an increase in elongation at break. Furthermore, in some examples, the samples showed improved fracture strength while simultaneously increasing elongation at break, indicating that the PLA-g-TBC samples exhibited the best overall performance. Among these, the sample in Example 9 demonstrated the best overall performance, indicating the successful preparation of a low-migration, high-strength, and high-toughness bio-based biodegradable TPV composite material.

[0038] Test Results Explanation (1) Amount of suitable viscosity ratio Examples 1-5 employed physical plasticization, and the optimal amount of plasticizer was determined through experiments such as apparent viscosity to bring the viscosity ratios of the two phases closer together. As shown in Figure 1, the addition of small molecule plasticizers significantly reduced the Tg of TPV, while increasing the elongation at break and decreasing the tensile strength. However, it can also be seen that the migration rates in the three solvents were very high. (2) Preparation of PLA-g-TBC This product uses functional isocyanates and multifunctional epoxy compounds to graft and modify PLA. By using the appropriate amount of plasticizer added in (1), grafting modification is carried out with different types and proportions of grafting agents to find the optimal viscosity ratio of PLA-g-TBC for subsequent dynamic vulcanization production. Through NMR analysis, it can be seen that TBC is grafted onto PLA molecules even without the addition of grafting agents. The appearance of the tributyl citrate skeleton near 4.2 ppm indicates that there is obvious grafting behavior. Combined with infrared data, it can be found that the disappearance of epoxy groups and the enhancement of the shoulder peak at 1160 cm-1 indicate that there is obvious grafting behavior. (3) Preparation of plasticized modified TPV The PLA-g-TBC prepared in the previous step was combined with a bio-based polyester elastomer to prepare a plasticized thermoplastic elastomer. Further characterization of the thermoplastic elastomer revealed that there was no obvious migration behavior in air and three solvents, and the plasticizing effect was excellent, with a significant increase in elongation at break. Furthermore, at a suitable viscosity ratio, the breaking strength also increased, thus improving the processing performance while maintaining the mechanical strength.

[0039] (4) Evaluation and measurement of plasticizing effect Atomic force microscopy (AFM) results show that with the simple addition of plasticizers, the original rubber particle size is very large, and the gel content decreases due to the plasticizer's influence. This leads to an increase in elongation at break, but a significant decrease in strength. However, the grafted TPV exhibits superior performance. AFM results show a significantly reduced particle size, with both increased elongation at break and good tensile strength. Furthermore, no significant migration behavior is observed.

[0040] The modified material exhibits a lower strength loss compared to pure polylactic acid (PLA) and a higher strength retention rate. The plasticity retention rate of the modified material is significantly higher than that of the unmodified plasticized material, and its modulus is even higher than that of pure TPV material. At the same time, thanks to the adjustment of the two-phase viscosity ratio, the tensile toughness and impact toughness of the material are further improved, thus producing a high-processability, high-strength, and high-toughness bio-based biodegradable PLA composite material.

[0041] The sequence numbers of the above embodiments of the present invention are merely for descriptive purposes and do not represent the superiority or inferiority of the embodiments. Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of some modifications and the superposition of necessary general technologies; of course, they can also be implemented by simplifying some important technical features at the higher level. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, is: the overall method and steps, and the methods described in conjunction with the various embodiments of the present invention.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bio-based thermoplastic vulcanizate, characterized in that, A multifunctional compound grafting agent is used to graft a bio-based small molecule plasticizer into polylactic acid (PLA) for single-phase plasticization to obtain plasticized graft-modified PLA. The plasticized graft-modified PLA is then mixed with a bio-based random copolyester elastomer and a vulcanizing agent and subjected to dynamic vulcanization to obtain the bio-based thermoplastic vulcanizate. The bio-based random copolyester elastomer is a copolymer of bio-based dicarboxylic acid, bio-based diol, and alkyd compound; the number-average molecular weight of the bio-based random copolyester elastomer is 5,000 to 80,000; and the number-average molecular weight of the polylactic acid is 20,000 to 250,000. The weight ratio of polylactic acid, bio-based small molecule plasticizer, and multifunctional compound grafting agent is 100:5-40:3-30; the weight ratio of bio-based random copolyester elastomer, vulcanizing agent, and plasticized grafted polylactic acid is 100:0.05-2:10-70.

2. The bio-based thermoplastic vulcanizate according to claim 1, characterized in that, The weight ratio of polylactic acid, bio-based small molecule plasticizer, and multifunctional compound grafting agent is 100:10-30:5-20.

3. The bio-based thermoplastic vulcanizate according to claim 1, characterized in that, The weight ratio of the bio-based random copolyester elastomer, vulcanizing agent, and plasticized graft-modified polylactic acid is 100:0.1-1:22-55.

4. The bio-based thermoplastic vulcanizate according to claim 1, characterized in that, The number-average molecular weight of the bio-based random copolyester elastomer is 5,000 to 20,000. The vulcanizing agent is any one or a combination of dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butyl peroxide), and dicumyl peroxide. The polylactic acid has a number-average molecular weight of 100,000 to 150,000. The bio-based small molecule plasticizer is any one or a combination of acetylated tributyl citrate, tributyl citrate, triacetyl triacetate, polyethylene glycol, and itaconic acid esters.

5. The bio-based thermoplastic vulcanizate according to claim 1, characterized in that, The multifunctional compound grafting agent includes isocyanate multifunctional groups and multifunctional epoxy compounds; The isocyanate polyfunctional group is any one or a combination of diphenylmethane diisocyanate MDI, hexamethylene diisocyanate HDI, 4,4'-dicyclohexylmethane diisocyanate HMDI, toluene diisocyanate TDI, and L-lysine diisocyanate LDI. The multifunctional epoxy compound is any one or a combination of epoxidized soybean oil, epoxidized cottonseed oil, polyethylene glycol diglycidyl ether, 2,2'-diepoxy ethylene, and polyethylene glycol glycidyl dodecyl ether.

6. The bio-based thermoplastic vulcanizate according to claim 1, characterized in that, The polylactic acid, bio-based small molecule plasticizer, and multifunctional plasticizer are prepared into plasticized graft modified polylactic acid in an internal mixer; the melt blending temperature in the internal mixer is 170-210℃, and the rotation speed is 60-120rpm. After mixing the plasticized grafted polylactic acid with bio-based random copolyester elastomer, a vulcanizing agent was added at room temperature and the mixture was placed in a mixer for dynamic vulcanization.

7. The bio-based thermoplastic vulcanizate according to claim 6, characterized in that, The temperature for melt blending in the internal mixer is 175–200℃, and the rotation speed is 80–100 rpm.

8. The bio-based thermoplastic vulcanizate according to claim 6, characterized in that, The plasticized grafted polylactic acid needs to be purified. During the purification process, the plasticized grafted polylactic acid needs to be dissolved in an organic solvent, then flocculated with an alcohol solvent and dried; the organic solvent is any one or a combination of dichloromethane, chloroform, tetrahydrofuran, acetone, ethyl acetate and dimethylformamide; the alcohol solvent is any one or a combination of methanol and ethanol.

9. The bio-based thermoplastic vulcanizate according to claim 6, characterized in that, The melting conditions for dynamic vulcanization in the internal mixer are maintained at a temperature of 150–200°C, a rotation speed of 60–120 rpm, and a time of 5–20 min.

10. The bio-based thermoplastic vulcanizate according to claim 9, characterized in that, The melting conditions for dynamic vulcanization in the internal mixer are maintained at a temperature of 175–185°C, a rotation speed of 80–100 rpm, and a time of 5–10 min.

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