Anti-permeation TPE (thermoplastic elastomer) inner pad material for food packaging and preparation method of anti-permeation TPE inner pad material

Abstract

The invention relates to the technical field of inner pad materials, and particularly discloses an impermeable TPE inner pad material for food packaging and a preparation method of the impermeable TPE inner pad material. According to the TPE inner pad material, the SEBS elastomer, the vinyl elastomer and the allyl elastomer are jointly used as base materials, under the synergistic effect of the block copolymerization lubricant and the amide lubricant, the TPE inner pad material can keep the opening torque of a bottle cap within a proper range, and the use experience of consumers is not prone to being affected. Moreover, the TPE inner pad material also has good oil resistance, can fully prevent grease components in food from permeating and diffusing into bottle caps, does not easily cause the situation that additives are dissolved into the food, and is particularly suitable for being applied to packaging of products such as seasoning sauce and the like.

Description

Technical Field

[0001] The present application relates to the technical field of inner padding materials, and more specifically, to an anti-permeability TPE inner padding material for food packaging and a preparation method thereof. Background Art

[0002] TPE refers to a type of elastomer that exhibits rubber-like elasticity at room temperature and plasticization at high temperatures. Its performance lies somewhere between that of plastic and rubber, and it is also known as the "third generation of rubber." Styrene-based thermoplastic elastomers (TPEs) are one of the primary types of TPE materials. Their emergence has greatly expanded their application range and has become an indispensable material in the food industry. The inner lining of bottle caps for ubiquitous products like beer, carbonated beverages, functional drinks, cooking oil, and sauces is often made of styrene-based TPEs.

[0003] Each country has its own testing standards for materials used in food. While these standards vary, they ultimately aim to ensure the appropriate materials are selected through testing. Most TPE manufacturers' products meet the requirements for testing with hydrophilic substances such as aqueous solutions, acetic acid, and alcohol. However, not all manufacturers' products meet the requirements for testing with oils and fats such as olive oil, n-hexane, and isooctane.

[0004] Related technologies have attempted to use initiators to trigger the crosslinking reaction between SBS and EVA, and to use PP-g-MAH to improve the bonding between the components in order to achieve oil resistance. However, EVA itself has poor tolerance to grease and easily precipitates into grease, and even crosslinking cannot completely correct this defect. In addition, crosslinking SBS and EVA will inevitably lead to increased resilience of the material. As an inner pad material, increased resilience means a greater opening torque, requiring consumers to expend more effort to open the bottle cap, which can easily affect the consumer experience.

[0005] Regarding the above-mentioned related technologies, the inventors believe that the TPE products in the related technologies have limited oil resistance and are not suitable for use in packaging bottle caps for oily foods. In addition, it will make opening the bottle caps more laborious, affecting the consumer's experience. Summary of the Invention

[0006] In the related art, TPE products have limited oil resistance, making them unsuitable for use in bottle caps for oily foods. Furthermore, opening the caps can be laborious, impacting the consumer experience. To address this shortcoming, the present application provides an impermeable TPE inner liner material for food packaging and a preparation method thereof.

[0007] In a first aspect, the present application provides an impermeable TPE inner pad material for food packaging, which adopts the following technical solution: A permeation-proof TPE inner padding material for food packaging comprises the following components in parts by weight: 35-45 parts of a SEBS elastomer, 25-35 parts of a vinyl elastomer, 20-25 parts of a propylene elastomer, 15-20 parts of polypropylene, 3-5 parts of sulfonated SEBS, 5-6 parts of a compatibilizer, 2-2.5 parts of a filler, 2-3 parts of a lubricant, and 0.3-0.5 parts of an antioxidant. The compatibilizer is a glycidyl methacrylate grafted polyolefin elastomer, and the lubricant comprises a block copolymer lubricant and an amide lubricant. The block copolymer lubricant is an acrylic copolymer grafted with polyzwitterionic side chains, wherein the polyzwitterionic side chains contain phosphorylcholine groups.

[0008] By adopting the above technical solution, the present application uses SEBS elastomer, vinyl elastomer and propylene elastomer as the base material, and adds sulfonated SEBS and block copolymer lubricant. Sulfonated SEBS is a sulfonated product of SEBS, has a main chain structure similar to SEBS, and is easy to be evenly dispersed in the TPE inner pad material. The block copolymer lubricant is composed of a main chain and a side chain, the main chain of which is an acrylic copolymer and the side chain is a polyzwitterionic side chain; the compatibilizer also contains an acrylic copolymer segment with a side chain, and also contains a polyolefin segment, so the compatibilizer can maintain good compatibility with the block copolymer lubricant, as well as with the SEBS elastomer, vinyl elastomer and propylene elastomer, thereby enabling the block copolymer lubricant to be evenly dispersed in the TPE inner pad material. The sulfonic acid groups in sulfonated SEBS and the polyzwitterionic side chains of the block copolymer lubricant possess a certain degree of hydrophilicity. Their synergistic effect effectively hinders the penetration and diffusion of oils and fats into the TPE inner lining material, thereby enhancing the TPE inner lining material's oil resistance. The polyzwitterionic side chains distributed on the surface of the PTE inner lining material also absorb moisture from food through the phosphorylcholine groups, forming a water film on the surface of the TPE inner lining material, thereby providing surface lubrication. The block copolymer lubricant itself is not easily transferred into food, and while providing lubrication, it also reduces the amount of amide lubricant required, helping to avoid the risk of excessive additives. The synergistic effect of the block copolymer lubricant and amide lubricant allows the TPE inner lining material of this application to maintain the opening torque of the bottle cap within an appropriate range, minimizing the impact on the consumer experience. Furthermore, the TPE inner lining material of this application exhibits excellent oil resistance, effectively preventing the penetration and diffusion of oils and fats in food into the bottle cap and preventing additives from dissolving into the food, making it particularly suitable for packaging products such as seasoning sauces.

[0009] Preferably, the block copolymer lubricant is prepared according to the following method: (1) adding a halide matrix, an electron donor ligand, and an unsaturated phosphorylcholine monomer to DMF, mixing, stirring evenly, and then bubbling with nitrogen; in this step, the halide matrix is ​​an ester produced by the reaction of polyhydroxyethyl acrylate and 2-bromoisobutyryl bromide; (2) adding copper bromide to DMF, mixing, stirring evenly, and then adding to the solution obtained in step (1), and continuing to bubbling with nitrogen; (3) heating the solution obtained in step (2) in a water bath, introducing air after the reaction is completed to terminate the reaction, then adding DMF and dialyzing, and freeze-drying after the dialysis is completed to obtain a block copolymer lubricant.

[0010] By adopting the above technical solution, the present application uses a halide matrix and an unsaturated phosphorylcholine monomer as main reactants, and carries out atom transfer radical polymerization with the assistance of an electron donor ligand and copper bromide, forming a polyzwitterionic side chain with a phosphorylcholine group on the main chain of the acrylic copolymer to obtain a block copolymer lubricant.

[0011] Preferably, the copper bromide is a mixture of copper bromide and cuprous bromide.

[0012] By adopting the above technical solution, the present application optimizes the composition of copper bromide, and the selection of a mixture of copper bromide and cuprous bromide can fully exert the role of copper bromide as a halogen atom carrier, so that the reaction can proceed fully.

[0013] Preferably, the halide matrix is ​​prepared according to the following method: (1) Polyhydroxyethyl acrylate, DMAP and triethylamine were added to acetone in sequence, and nitrogen was introduced into the reaction system for protection; (2) adding 2-bromoisobutyryl bromide to the solution obtained in step (1), starting the reaction under ice bath conditions, continuously stirring during the reaction, and separating the generated precipitate by filtration, dialysis-purifying the separated precipitate, and freeze-drying the dialyzed purified precipitate to obtain a halide matrix.

[0014] By adopting the above technical solution, the present application uses polyhydroxyethyl acrylate and 2-bromoisobutyryl bromide as reactants with the assistance of DMAP and triethylamine, and prepares an esterification product, namely a halide matrix, based on the principle of Schotten-Baumann reaction.

[0015] Preferably, the amide lubricant includes one of hydroxyethyl ethylene bisstearamide and ethylene bisricinoleamide.

[0016] By adopting the above technical solution, this application optimizes the type of amide lubricant. This amide lubricant works well with the block copolymer lubricant, maintaining an appropriate level of difficulty in opening the bottle cap and helping to avoid impacting the consumer experience. Furthermore, the hydroxyl groups in these two amide lubricant molecules can also hinder the intrusion of grease, synergistically improving the oil resistance of the TPE inner pad material with the sulfonated SEBS and block copolymer lubricant.

[0017] Preferably, the sulfonated SEBS is prepared as follows: SEBS is added to an organic solvent and stirred to dissolve to obtain a SEBS dispersion. Acetylsulfuric acid sulfonating agent is added to the SEBS dispersion. After stirring, deionized water is added to terminate the reaction. The organic solvent is evaporated with water vapor, and the product is washed with deionized water and then dried to obtain sulfonated SEBS.

[0018] By adopting the above technical solution, the present application sulfonated SEBS using an acetylsulfuric acid sulfonating agent, introduced sulfonic acid groups into SEBS, and obtained sulfonated SEBS.

[0019] Preferably, the organic solvent is at least one of 1,2-dichloroethane and chloroform.

[0020] By adopting the above technical solution, 1,2-dichloroethane can inhibit the coagulation of SEBS, while chloroform has a better dissolution effect on SEBS. When the two are used together, they can prevent product coagulation while maintaining a homogeneous reaction, which helps to achieve a more ideal degree of sulfonation.

[0021] Preferably, the acetylsulfuric acid sulfonating agent is prepared as follows: Acetic anhydride is added to an organic solvent under ice bath conditions and stirred to cool down, and then concentrated sulfuric acid is added to react. After the reaction is completed, the ice bath is removed and stirring is continued to obtain an acetylsulfuric acid sulfonating agent.

[0022] By adopting the above technical solution, the present application uses acetic anhydride and concentrated sulfuric acid as reactants to prepare an acetylsulfuric acid sulfonating agent, which can be used to sulfonate SEBS.

[0023] Preferably, the acetylsulfuric acid sulfonating agent is prepared from acetic anhydride and concentrated sulfuric acid in a molar ratio of (2-2.5):1.

[0024] By adopting the above technical solution, the present application optimizes the raw material composition of the acetylsulfuric acid sulfonating agent, which helps to fully realize the sulfonation of SEBS.

[0025] In a second aspect, the present application provides a method for preparing an impermeable TPE inner pad material for food packaging, which adopts the following technical solution.

[0026] A method for preparing an impermeable TPE inner pad material for food packaging comprises the following steps: (1) SEBS elastomer, vinyl elastomer and propylene elastomer are mixed to obtain an elastomer mixture, which is then used for subsequent use; (2) The elastomer mixture, polypropylene, modified SEBS, filler, lubricant, and antioxidant are added to a mixer and mixed, and then extruded and granulated to obtain an impermeable TPE inner pad material for food packaging.

[0027] By adopting the above technical solution, this application uses SEBS elastomer, vinyl elastomer and propylene elastomer as the base material, adds modified SEBS, fillers, lubricants, antioxidants and other additives, and prepares an anti-permeability TPE inner padding material for food packaging with good oil resistance and moderate elasticity.

[0028] In summary, this application has the following beneficial effects: 1. Under the synergistic effect of the block copolymer lubricant and the amide lubricant, the TPE inner pad material of the present application can maintain the opening torque of the bottle cap within an appropriate range and is not likely to affect the consumer's experience.

[0029] 2. The TPE inner pad material of the present application has good oil resistance, which can fully prevent the oil components in the food from penetrating and diffusing into the bottle cap, and it is not easy for additives to dissolve into the food. It is particularly suitable for the packaging of products such as seasoning sauces.

[0030] 3. This application optimizes the type of solvent used in the preparation of sulfonated SEBS and limits the composition ratio of the sulfonating agent, which helps to fully achieve the sulfonation of SEBS. DETAILED DESCRIPTION

[0031] The present application is further described in detail below with reference to the Examples, Preparation Examples and Comparative Examples. The raw materials involved in the present application can all be obtained commercially.

[0032] Preparation Example of Block Copolymer Lubricant The following is an explanation using Preparation Example 1.

[0033] Preparation Example 1 In this preparation example, the electron donor ligand is bpy, and the unsaturated phosphorylcholine monomer is 2-methacryloyloxyethyl phosphorylcholine. The halide matrix in this preparation example was prepared as follows: (1) 1.85 g of poly(hydroxyethyl acrylate), 26 mmol of DMAP and 26 mmol of triethylamine were added to 40 mL of acetone in sequence, and nitrogen was introduced into the reaction system for protection; in this step, the average molecular weight of poly(hydroxyethyl acrylate) was 100 KDa; (2) 12.1 g of 2-bromoisobutyryl bromide was added to the solution obtained in step (1), and the reaction was started under ice bath conditions. During the reaction, stirring was continued, and the precipitate produced was continuously separated by filtration. After the temperature of the reaction system rose to room temperature of 25° C., the reaction was continued for 19 hours, and then the separated precipitate was dialyzed for purification. The dialysis was carried out for a total of 3 days, and the water was changed every 12 hours. The dialyzed and purified precipitate was freeze-dried to obtain a halide matrix.

[0034] This preparation example provides a block copolymer lubricant, which is prepared according to the following method: (1) 10 g of halide matrix, 13.86 g of electron donor ligand, and 80 g of unsaturated phosphorylcholine monomer were added to 800 mL of DMF, mixed, and stirred until uniform, and then nitrogen was bubbled through for 40 min; (2) 5.76 g of cuprous bromide and 0.98 g of cupric bromide were added to 200 mL of DMF, mixed, stirred evenly, and added to the solution obtained in step (1), and nitrogen bubbling was continued for 10 min; (3) The solution obtained in step (2) was heated in a water bath at 30° C. for 12 h. The reaction was terminated by introducing air, and then DMF was added and dialyzed. The dialysis was carried out for 3 days, with water being changed every 12 h. After the dialysis was completed, the solution was freeze-dried to obtain a block copolymer lubricant.

[0035] Preparation Example of Sulfonated SEBS The following is an illustration of Preparation Example 2.

[0036] Preparation Example 2 In this preparation example, the SEBS has a styrene content of 32 wt% and an average molecular weight of 250,000. 1,2-dichloroethane is used as the organic solvent, and acetyl sulfate sulfonating agent is prepared as follows: Acetic anhydride and concentrated sulfuric acid were weighed in a molar ratio of 1:1, and the acetic anhydride was added to an organic solvent under ice bath conditions and stirred to cool. Then, concentrated sulfuric acid was added to react. After 30 minutes, the ice bath was removed and stirring was continued for 10 minutes to obtain an acetylsulfuric acid sulfonating agent with a solute concentration of 25 wt%.

[0037] This preparation example provides a sulfonated SEBS, which is prepared according to the following method: 10 g of SEBS was added to 100 mL of an organic solvent and stirred to dissolve to obtain a SEBS dispersion. 8 g of an acetyl sulfate sulfonating agent was added to the SEBS dispersion. After stirring at 50° C. for 4 h, deionized water was added to terminate the reaction. The organic solvent was evaporated with steam, and the product was washed with deionized water and then dried to obtain sulfonated SEBS.

[0038] Preparation Example 3 The difference between this preparation example and preparation example 2 is that chloroform is used as the organic solvent.

[0039] Preparation Example 4 The difference between this preparation example and preparation example 2 is that the organic solvent is a mixture of 1,2-dichloroethane and chloroform in a weight ratio of 1:2.

[0040] Preparation Example 5 The difference between this preparation example and preparation example 4 is that the acetylsulfuric acid sulfonating agent is prepared from acetic anhydride and concentrated sulfuric acid in a molar ratio of 2:1.

[0041] Preparation Example 6 The difference between this preparation example and preparation example 4 is that the acetylsulfuric acid sulfonating agent is prepared from acetic anhydride and concentrated sulfuric acid in a molar ratio of 2.2:1.

[0042] Preparation Example 7 The difference between this preparation example and preparation example 4 is that the acetylsulfuric acid sulfonating agent is prepared from acetic anhydride and concentrated sulfuric acid in a molar ratio of 2.5:1. Example

[0043] Examples 1-3 The following description will be given using Example 1 as an example.

[0044] Example 1 In this embodiment, the styrene content of SEBS is 32 wt % and the average molecular weight is 250,000. The comonomer of the vinyl elastomer is octene, wherein the octenyl content is 25 wt %. The comonomer of the propylene elastomer is ethylene, wherein the vinyl content is 10 wt %. The melt index of polypropylene is 1200 g / 10 min, and the test conditions are 230° C.*2.16 kg. Sulfonated SEBS is prepared according to the method of Preparation Example 2, and the compatibilizer is glycidyl methacrylate grafted polyolefin elastomer ( SOG-02 is POE-g-GMA, and the filler is rutile titanium dioxide. The lubricant is a mixture of a block copolymer lubricant and an amide lubricant in a weight ratio of 3:1. The block copolymer lubricant is prepared according to the method of Preparation Example 1. The amide lubricant is oleamide. The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a weight ratio of 3:1.

[0045] This embodiment provides an impermeable TPE inner pad material for food packaging, including the following components: 35g of SEBS elastomer, 25g of vinyl elastomer, 20g of propylene elastomer, 15g of polypropylene, 3g of sulfonated SEBS, 5g of compatibilizer, 2g of filler, 2g of lubricant, and 0.3g of antioxidant.

[0046] This embodiment provides a method for preparing an impermeable TPE inner pad material for food packaging, comprising the following steps: (1) SEBS elastomer, vinyl elastomer and propylene elastomer are mixed to obtain an elastomer mixture, which is then used for subsequent use; (2) The elastomer mixture, polypropylene, modified SEBS, filler, lubricant, and antioxidant are added to a mixer and mixed, and then extruded and granulated at 210° C. to obtain an impermeable TPE inner pad material for food packaging.

[0047] As shown in Table 1, the main difference between Examples 1-3 is that the raw material ratios of the TPE inner pad material are different.

[0048] Table 1 Ratio of raw materials of TPE inner pad Example 4 The difference between this embodiment and embodiment 3 is that the amide lubricant is ethylene bis ricinoleamide.

[0049] Example 5 The difference between this embodiment and embodiment 3 is that the amide lubricant is hydroxyethyl ethylene bisstearamide.

[0050] Examples 5-10 As shown in Table 2, the difference between Examples 5-10 is that the preparation examples of sulfonated SEBS are different.

[0051] Table 2 Preparation example of sulfonated SEBS sample Preparation Example Example 5 Preparation Example 2 Example 6 Preparation Example 3 Example 7 Preparation Example 4 Example 8 Preparation Example 5 Example 9 Preparation Example 6 Example 10 Preparation Example 7 Comparative Example Comparative Example 1 The difference between this comparative example and Example 1 is that the components of the TPE inner pad material do not include a block copolymer lubricant.

[0052] Comparative Example 2 This comparative example is different from Example 1 in that the components of the TPE inner pad material do not include sulfonated SEBS.

[0053] Comparative Example 3 The difference between this comparative example and Example 1 is that the components of the TPE inner pad material do not include a compatibilizer.

[0054] Performance testing methods The sauce used in the following tests is Pixian Doubanjiang, which complies with the provisions for premium products in GB / T 20560-2006, Geographical Indication Product Pixian Doubanjiang.

[0055] 1. Opening torque In accordance with GB / T 17876-2010, "Plastic Anti-theft Bottle Caps for Packaging Containers," commercially available plastic bottles of Pixian fermented bean paste were tested. The results are shown in Table 3. The plastic bottles were made of polyethylene and had the following dimensions: height 13 cm, lid diameter 8 cm, base diameter 10 cm, and mouth diameter 7 cm.

[0056] 2. Oil resistance Referring to the provisions of GB 4806.7-2023 “Plastic Materials and Articles for Food Contact”, the total migration of isooctane was tested under the test conditions of 37°C for 20 days with the sample inverted. The test results are shown in Table 3.

[0057] Table 3 Combining Example 1 with Comparative Example 1 and Table 3, it can be seen that the synergistic effect of the block copolymer lubricant and the amide lubricant allows the TPE inner liner material of Example 1 to maintain the opening torque of the bottle cap within an appropriate range, effectively preventing it from impacting the consumer experience. The synergistic effect of sulfonated SEBS and the block copolymer lubricant effectively hinders the penetration and diffusion of oils and fats within the TPE inner liner material, thereby enhancing the TPE inner liner material's oil resistance and reducing the total isooctane migration. In contrast, Comparative Example 1 fails to achieve this synergistic effect of lubrication and oil resistance, resulting in a higher opening torque and a larger total isooctane migration, significantly impacting the consumer experience.

[0058] Combining Example 3 and Comparative Example 2 with Table 3, it can be seen that the total isooctane migration amount measured in Example 1 is relatively small. This is because Comparative Example 2 lacks sulfonated SEBS, and the synergistic effect of sulfonated SEBS and block copolymer lubricant cannot fully hinder the penetration and diffusion of oily substances.

[0059] Combining Example 3 and Comparative Example 3 with Table 3, it can be seen that the total isooctane migration amount measured in Example 1 is relatively small. This is because Comparative Example 3 lacks a compatibilizer, which results in the block copolymer lubricant being unable to be effectively dispersed, thereby affecting the full play of the synergistic effects of lubrication and oil resistance, resulting in unsatisfactory test results.

[0060] Combining Examples 3 and 4-5 with Table 3, it can be seen that the total isooctane migration measured in Examples 4-5 is relatively small. This is because the hydroxyl groups in the hydroxyethyl ethylene bisstearamide and ethylene bisricinoleamide molecules can hinder the invasion of oil and fat, and synergistically improve the oil resistance of the TPE inner pad material with the sulfonated SEBS and block copolymer lubricant.

[0061] Combining Examples 5-7 with Table 3, it can be seen that the total isooctane migration amounts measured in Examples 5-7 decrease successively. This is because chloroform has a better dissolving effect on SEBS, and when chloroform is used in combination with 1,2-dichloroethane, it can prevent product coagulation while maintaining a homogeneous reaction, which is more conducive to achieving a more ideal degree of sulfonation.

[0062] Combining Examples 7-10 with Table 3, it can be seen that the total isooctane migration measured in Examples 8-10 is relatively small. This is because the sulfonation of SEBS is fully achieved within the sulfonating agent ratio range specified in this application, thereby improving the oil resistance of the TPE inner pad material.

[0063] The above embodiments are merely explanations of the present application and are not limitations of the present application. After reading this specification, those skilled in the art may make modifications to the embodiments of the present application as needed without any creative contribution. However, as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. An anti-permeability TPE inner pad material for food packaging, characterized in that: The invention comprises the following components in parts by weight: 35-45 parts of SEBS elastomer, 25-35 parts of vinyl elastomer, 20-25 parts of propylene elastomer, 15-20 parts of polypropylene, 3-5 parts of sulfonated SEBS, 5-6 parts of compatibilizer, 2-2.5 parts of filler, 2-3 parts of lubricant, and 0.3-0.5 parts of antioxidant; the compatibilizer is glycidyl methacrylate grafted polyolefin elastomer, the lubricant comprises a block copolymer lubricant and an amide lubricant, the block copolymer lubricant is an acrylic copolymer grafted with polyzwitterionic side chains, and the polyzwitterionic side chains contain phosphorylcholine groups.

2. The anti-permeability TPE inner pad material for food packaging according to claim 1, characterized in that: The block copolymer lubricant is prepared as follows: (1) Adding a halide matrix, an electron donor ligand, and an unsaturated phosphorylcholine monomer to DMF, mixing, stirring evenly, and then bubbling with nitrogen; in this step, the halide matrix is ​​an ester produced by the reaction of polyhydroxyethyl acrylate and 2-bromoisobutyryl bromide; (2) adding copper bromide to DMF, mixing, stirring evenly, and then adding to the solution obtained in step (1), and continuing to bubbling with nitrogen; (3) The solution obtained in step (2) is heated in a water bath. After the reaction is completed, air is introduced to terminate the reaction. DMF is then added and dialyzed. After the dialysis is completed, the solution is freeze-dried to obtain a block copolymer lubricant.

3. The anti-permeability TPE inner pad material for food packaging according to claim 2, characterized in that: The copper bromide is a mixture of copper bromide and cuprous bromide.

4. The anti-permeability TPE inner pad material for food packaging according to claim 2, characterized in that: The halide matrix is ​​prepared as follows: (1) Polyhydroxyethyl acrylate, DMAP and triethylamine were added to acetone in sequence, and nitrogen was introduced into the reaction system for protection; (2) Adding 2-bromoisobutyryl bromide to the solution obtained in step (1), starting the reaction under ice bath conditions, continuously stirring during the reaction, and separating the generated precipitate by filtration, dialysis-purifying the separated precipitate, and freeze-drying the dialyzed purified precipitate to obtain a halide matrix.

5. The anti-permeability TPE inner pad material for food packaging according to claim 2, characterized in that: The amide lubricant includes one of hydroxyethyl ethylene bisstearamide and ethylene bisricinoleamide.

6. The anti-permeability TPE inner pad material for food packaging according to claim 1, characterized in that: The sulfonated SEBS was prepared as follows: SEBS is added to an organic solvent and stirred to dissolve to obtain a SEBS dispersion. Acetylsulfuric acid sulfonating agent is added to the SEBS dispersion. After stirring, deionized water is added to terminate the reaction. The organic solvent is evaporated with water vapor, and the product is washed with deionized water and then dried to obtain sulfonated SEBS.

7. The anti-permeability TPE inner pad material for food packaging according to claim 6, characterized in that: The organic solvent is selected from at least one of 1,2-dichloroethane and chloroform.

8. The anti-permeability TPE inner pad material for food packaging according to claim 6, characterized in that: The acetylsulfuric acid sulfonating agent is prepared as follows: Acetic anhydride is added to an organic solvent under ice bath conditions and stirred to cool down, and then concentrated sulfuric acid is added to react. After the reaction is completed, the ice bath is removed and stirring is continued to obtain an acetylsulfuric acid sulfonating agent.

9. The anti-permeability TPE inner pad material for food packaging according to claim 8, characterized in that: The acetylsulfuric acid sulfonating agent is prepared from acetic anhydride and concentrated sulfuric acid in a molar ratio of (2-2.5):

1.

10. The method for preparing the impermeable TPE inner pad material for food packaging according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) SEBS elastomer, vinyl elastomer, and propylene elastomer are mixed to obtain an elastomer mixture for later use; (2) The elastomer mixture, polypropylene, modified SEBS, filler, lubricant, and antioxidant are added to a mixer and mixed, and then extruded and granulated to obtain an impermeable TPE inner pad material for food packaging.

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