Grease-resistant food-grade TPE (Thermoplastic Elastomer) inner pad material and preparation method thereof

Abstract

The invention relates to the field of inner pad materials, in particular to a grease-resistant food-grade TPE (thermoplastic elastomer) inner pad material and a preparation method thereof.The grease-resistant food-grade TPE inner pad material adopts a white-oil-free formula, adopts high-melt-index polypropylene to improve the fluidity of the inner pad material, and selects a propenyl elastomer and a vinyl elastomer as elastomers; amine modified SEBS is introduced into the inner pad material; erucyl amide and bis (12-hydroxystearic acid) amide are selected to be compounded as an amide lubricant; the preparation method comprises the following steps: preparing a copper-doped titanium dioxide nanosheet through an in-situ hydrothermal method; the preparation method comprises the following steps: immersing a copper-doped titanium dioxide nanosheet into a tri (hydroxymethyl) methyl aminomethane solution compounded by epigallocatechin gallate and epsilon-polylysine by adopting a liquid phase deposition method, preparing a phenol amine layer on the copper-doped titanium dioxide nanosheet, and connecting the phenol amine layer with modified carboxymethyl chitosan through electrostatic interaction.

Description

Technical Field

[0001] The present invention relates to the technical field of inner padding materials, in particular to a grease-resistant food-grade TPE inner padding material and a preparation method thereof. Background Art

[0002] TPE material is a type of elastomer that has the elasticity of rubber at room temperature and is plasticized and formed at high temperatures. It is widely used in food-related bottle cap lining materials such as beer, beverages, cooking oil, and seasonings.

[0003] When it comes to food application testing, most commercially available TPEs meet regulatory requirements in tests with aqueous solutions, acetic acid, and alcohol. However, they often perform poorly in tests with oils and fats, such as olive oil, n-hexane, and isooctane. For example, patent CN115109380B describes an oil-resistant, food-grade styrene-based thermoplastic elastomer and its preparation method. In this method, SEBS and SBS, among other main components, are cross-linked with an initiator. The elastomer is then combined with naphthenic oil, EVA, and PP-g-MAH to adjust the system's vulcanization uniformity and fluidity, improving its tolerance to organic solvents like olive oil. However, EVA itself has poor tolerance to oils and fats, precipitating into the oils and fats, making it impossible to ensure full cross-linking and stable cross-linking. Furthermore, cross-linking SBS and EVA results in increased material resilience. For inner lining materials, excessively high resilience results in increased opening torque, which can negatively impact the consumer experience. Furthermore, the antibacterial and antimicrobial properties of bottle caps are closely linked to food freshness. Summary of the Invention

[0004] The object of the present invention is to provide a grease-resistant food-grade TPE inner pad material and a preparation method thereof, so as to solve the problems in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: A grease-resistant food-grade TPE inner pad material comprises, by weight, 20-40 parts of SEBS, 10-30 parts of propylene elastomer, 20-40 parts of vinyl elastomer, 10-20 parts of polypropylene, 3-10 parts of amine-modified SEBS, 0.5-1.5 parts of filler, 1-3 parts of amide lubricant, and 0.1-0.5 parts of antioxidant.

[0006] Furthermore, the comonomer of the propylene-based elastomer is ethylene, wherein the vinyl content is 5-20%.

[0007] Furthermore, the comonomer of the vinyl elastomer is octene, and the copolymerization form is block type, wherein the octene content is 20-30%.

[0008] Furthermore, the amide lubricant is obtained by compounding erucamide and didodecyl hydroxystearamide in a mass ratio of (0.5-1): (0.6-1.7).

[0009] Furthermore, a grease-resistant food-grade TPE inner pad material is provided, wherein the composition of the TPE inner pad material is, by weight: SEBS: 20-40 parts, propylene elastomer: 10-30 parts, vinyl elastomer: 20-40 parts, polypropylene: 10-20 parts, amine-modified SEBS: 3-10 parts, filler: 0.5-1.5 parts, amide lubricant: 1.1-1.8 parts, and antioxidant 0.1-0.5 parts.

[0010] Furthermore, the antioxidant is obtained by compounding antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.

[0011] Furthermore, the filler is rutile titanium dioxide.

[0012] Furthermore, the filler is a composite titanium dioxide nanosheet, and the preparation includes the following steps: (1) Anhydrous ethanol, tetrabutyl titanate, hydrogen fluoride, and copper nitrate trihydrate were stirred for 20-30 minutes, transferred to a hydrothermal kettle, kept at 178-182°C for 110-130 minutes, centrifuged, washed, dried, and ground to obtain copper-doped titanium dioxide nanosheets; (2) epigallocatechin gallate and tris(hydroxymethyl)methylaminomethane solution were mixed, ε-polylysine and tris(hydroxymethyl)methylaminomethane solution were added, copper-doped titanium dioxide nanosheets were added, and the mixture was kept at 35-39°C for 22-24 hours, washed, dried, and ground to obtain modified titanium dioxide nanosheets; (3) The modified titanium dioxide nanosheets and sodium acetate buffer solution were mixed, the pH was adjusted to 7.5, and a mixture of modified carboxymethyl chitosan and sodium acetate buffer solution was added, the pH was adjusted to 7.5, and the mixture was shaken at 35-39°C for 3-4 hours, centrifuged, filtered, and freeze-dried to obtain composite titanium dioxide nanosheets.

[0013] Furthermore, the mass ratio of the modified titanium dioxide nanosheets to the modified carboxymethyl chitosan is 1:0.8.

[0014] Furthermore, the preparation of modified carboxymethyl chitosan comprises the following steps: Mix carboxymethyl chitosan and deionized water, stir at 18-25°C for 50-70 minutes, heat to 77-83°C and keep warm in an oil bath for 20-30 minutes, add a mixture of ethanol, stearic acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide, continue to keep warm for 6-8 hours, cool, stir at 18-25°C for 22-24 hours, precipitate with ethanol, centrifuge, wash, dialyze in deionized water for 72 hours, and freeze-dry to obtain modified carboxymethyl chitosan.

[0015] Furthermore, a method for preparing a grease-resistant food-grade TPE inner pad material comprises the following steps: SEBS, propylene elastomer, vinyl elastomer, polypropylene, amine-modified SEBS, filler, amide lubricant, and antioxidant are sequentially added into a high-speed mixer, mixed, and then extruded and granulated to obtain a grease-resistant food-grade TPE inner pad material.

[0016] Furthermore, the extrusion temperature is: 170-220°C.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a grease-resistant food-grade TPE inner pad material and a preparation method thereof. By optimizing the formula and process, a grease-resistant food-grade TPE inner pad material is prepared that is safe, has good antibacterial properties, and has good bonding strength with bottle caps. By controlling the raw material ratio, the material has moderate resilience to simultaneously take into account sealing properties and opening torque, and has high economic value and practical significance.

[0018] The present invention adopts a white oil-free formula and directly polymerized high melt index polypropylene to improve the fluidity of the inner pad material, solve the problem of "initiator residue" existing in existing inner pad materials, and improve food safety. In order to improve the relative tolerance of the inner pad material to immersion in olive oil, n-hexane, and isooctane, a propylene-based elastomer with ethylene as a comonomer and a vinyl elastomer with octene as a comonomer in a block copolymer form are selected as the elastomer. Since propylene and ethylene are relatively tolerant to immersion in isooctane and the like, by controlling their ratio, the high temperature resistance, sealing performance, and opening torque of the inner pad material are improved. Amine-modified SEBS is introduced into the inner pad material. The amino component in the amine-modified SEBS is utilized to increase the adaptability of the inner pad material to different coatings of the bottle cap, expand its scope of use, enhance its tolerance to grease or isooctane, and reduce the probability of the product being dyed. Compared with anhydride-modified SEBS, the introduction of amine-modified SEBS has a better odor and reduces the impact on the taste of the contents.

[0019] A combination of erucamide and didohydroxystearamide is selected as an amide lubricant. Erucamide precipitates quickly, ensuring the initial screw-in distance of the bottle cap, while didohydroxystearamide precipitates relatively slowly, ensuring the long-term stability of the opening torque. At the same time, the introduction of a large number of hydrophilic groups in didohydroxystearamide can prevent oily substances from entering the inner pad material, improve the oil resistance of the inner pad material, and synergistically reduce the chance of the product being dyed.

[0020] In order to further improve the mechanical strength and antibacterial properties of the inner pad material, titanium dioxide was selected as a filler. To improve the antibacterial properties of titanium dioxide, copper-doped titanium dioxide nanosheets were prepared by in-situ hydrothermal method to improve their activity. In order to improve the bonding strength between the copper-doped titanium dioxide nanosheets and the inner pad material base material and improve the uniformity of the copper-doped titanium dioxide nanosheets dispersed in the inner pad material, the copper-doped titanium dioxide nanosheets were immersed in a tris(hydroxymethyl)methylaminomethane solution of epigallocatechin gallate and ε-polylysine by liquid phase deposition method to prepare a phenolamine layer on the copper-doped titanium dioxide nanosheets. The introduction of epigallocatechin gallate and ε-polylysine has a green antibacterial effect and improves food safety. In order to further synergistically improve the oil resistance of the inner pad material, the electrostatic interaction between them and modified carboxymethyl chitosan is enhanced by controlling the process parameters. The modified carboxymethyl chitosan is acylated with stearic acid on the amino group of carboxymethyl chitosan using 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide as catalysts. By controlling the amount of their introduction, the oil resistance and antibacterial properties of the inner pad material are synergistically improved, thereby greatly expanding the scope of use of the inner pad material. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] It should be noted that if the embodiments of the present invention involve directional indications such as up, down, left, right, front, and back, such directional indications are only used to explain a specific posture, such as the relative position relationship between components, the movement status, etc. If the specific posture changes, the directional indication will also change accordingly. In addition, the technical solutions between the various embodiments may be combined with each other, but they must be based on the premise that they can be implemented by ordinary technicians in this field. If the combination of technical solutions is mutually inconsistent or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0023] The technical solutions of the present invention are further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely used to explain the present invention and are not intended to limit the present invention.

[0024] Example 1: A method for preparing a grease-resistant food-grade TPE inner pad material, comprising the following steps: SEBS, propylene elastomer, vinyl elastomer, polypropylene, amine-modified SEBS, filler, amide lubricant, and antioxidant are sequentially added into a high-speed mixer, mixed, and then extruded and granulated to obtain a grease-resistant food-grade TPE inner pad material; Extrusion temperature: 180℃; The composition of the TPE inner pad material is as follows, by mass: SEBS: 20 parts, propylene elastomer: 28 parts, vinyl elastomer: 20 parts, polypropylene: 20 parts, amine-modified SEBS: 10 parts, filler: 0.5 parts, amide lubricant: 1.1 parts, antioxidant 0.4 parts; The amide lubricant is obtained by mixing erucamide and didodecyl hydroxystearamide in a mass ratio of 0.5:0.6; and the filler is titanium dioxide.

[0025] Example 2: A method for preparing a grease-resistant food-grade TPE inner pad material, comprising the following steps: SEBS, propylene elastomer, vinyl elastomer, polypropylene, amine-modified SEBS, filler, amide lubricant, and antioxidant are sequentially added into a high-speed mixer, mixed, and then extruded and granulated to obtain a grease-resistant food-grade TPE inner pad material; Extrusion temperature: 180℃; The composition of the TPE inner pad material is as follows, by mass: SEBS: 20 parts, propylene elastomer: 10 parts, vinyl elastomer: 20 parts, polypropylene: 10 parts, amine-modified SEBS: 3 parts, filler: 0.5 parts, amide lubricant: 1.1 parts, antioxidant 0.1 parts; The amide lubricant is obtained by mixing erucamide and didodecyl hydroxystearamide in a mass ratio of 0.5:0.6; The filler is a composite titanium dioxide nanosheet, and the preparation includes the following steps: (1) 40 mL of anhydrous ethanol, 10 mL of tetrabutyl titanate, 1.2 mL of hydrogen fluoride, and 355 mg of copper nitrate trihydrate were stirred for 20 min, transferred to a hydrothermal reactor, and kept at 178 °C for 130 min. The mixture was centrifuged, washed, dried, and ground to obtain copper-doped titanium dioxide nanosheets. (2) 80 mg of epigallocatechin gallate and 20 mL of tris(hydroxymethyl)methylaminomethane solution were mixed, 80 mg of ε-polylysine and 20 mL of tris(hydroxymethyl)methylaminomethane solution were added, and 50 mg of copper-doped titanium dioxide nanosheets were added. The mixture was kept at 35 ° C for 24 h, washed, dried, and ground to obtain modified titanium dioxide nanosheets. (3) 1 g of modified titanium dioxide nanosheets and 20 mL of sodium acetate buffer were mixed, the pH was adjusted to 7.5, 0.8 g of modified carboxymethyl chitosan and 20 mL of sodium acetate buffer were added, the pH was adjusted to 7.5, and the mixture was shaken at 35 °C for 4 h, centrifuged, filtered, and freeze-dried to obtain composite titanium dioxide nanosheets; The preparation of the modified carboxymethyl chitosan comprises the following steps: 0.2 g of carboxymethyl chitosan and 20 mL of deionized water were mixed, stirred at 18 ° C for 70 minutes, heated to 77 ° C in an oil bath and kept warm for 30 minutes, and a mixture of 20 mL of ethanol, 3 mg of stearic acid, 2 mg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, and 2 mg of N-hydroxysuccinimide was added. The mixture was kept warm for 6 hours, cooled, stirred at 18 ° C for 24 hours, precipitated with ethanol, centrifuged, washed, dialyzed in 50 mL of deionized water for 72 hours, and freeze-dried to obtain modified carboxymethyl chitosan.

[0026] Example 3: A method for preparing a grease-resistant food-grade TPE inner pad material, comprising the following steps: SEBS, propylene elastomer, vinyl elastomer, polypropylene, amine-modified SEBS, filler, amide lubricant, and antioxidant are sequentially added into a high-speed mixer, mixed, and then extruded and granulated to obtain a grease-resistant food-grade TPE inner pad material; Extrusion temperature: 180℃; The composition of the TPE inner pad material is as follows, by mass: SEBS: 30 parts, propylene elastomer: 20 parts, vinyl elastomer: 30 parts, polypropylene: 15 parts, amine-modified SEBS: 7 parts, filler: 1 part, amide lubricant: 1.6 parts, antioxidant 0.4 parts; The amide lubricant is obtained by mixing erucamide and didodecyl hydroxystearamide in a mass ratio of 1:0.6; The filler is a composite titanium dioxide nanosheet, and the preparation includes the following steps: (1) 40 mL of anhydrous ethanol, 10 mL of tetrabutyl titanate, 1.2 mL of hydrogen fluoride, and 355 mg of copper nitrate trihydrate were stirred for 25 min, transferred to a hydrothermal autoclave, and kept at 180 °C for 120 min. The mixture was centrifuged, washed, dried, and ground to obtain copper-doped titanium dioxide nanosheets. (2) 80 mg of epigallocatechin gallate and 20 mL of tris(hydroxymethyl)methylaminomethane solution were mixed, 80 mg of ε-polylysine and 20 mL of tris(hydroxymethyl)methylaminomethane solution were added, and 50 mg of copper-doped titanium dioxide nanosheets were added. The mixture was kept at 37 ° C for 23 h, washed, dried, and ground to obtain modified titanium dioxide nanosheets. (3) 1 g of modified titanium dioxide nanosheets and 20 mL of sodium acetate buffer were mixed, the pH was adjusted to 7.5, 0.8 g of modified carboxymethyl chitosan and 20 mL of sodium acetate buffer were added, the pH was adjusted to 7.5, and the mixture was shaken at 37 °C for 3.5 h, centrifuged, filtered, and freeze-dried to obtain composite titanium dioxide nanosheets; The preparation of the modified carboxymethyl chitosan comprises the following steps: Mix 0.2 g of carboxymethyl chitosan and 20 mL of deionized water, stir at 20 ° C for 60 minutes, heat to 80 ° C in an oil bath and keep warm for 25 minutes, add a mixture of 20 mL of ethanol, 3 mg of stearic acid, 2 mg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, and 2 mg of N-hydroxysuccinimide, continue to keep warm for 7 hours, cool, stir at 20 ° C for 23 hours, precipitate with ethanol, centrifuge, wash, dialyze in 50 mL of deionized water for 72 hours, and freeze-dry to obtain modified carboxymethyl chitosan.

[0027] Example 4: A method for preparing a grease-resistant food-grade TPE inner pad material, comprising the following steps: SEBS, propylene elastomer, vinyl elastomer, polypropylene, amine-modified SEBS, filler, amide lubricant, and antioxidant are sequentially added into a high-speed mixer, mixed, and then extruded and granulated to obtain a grease-resistant food-grade TPE inner pad material; Extrusion temperature: 180℃; The composition of the TPE inner pad material is as follows, by mass: SEBS: 40 parts, propylene elastomer: 30 parts, vinyl elastomer: 40 parts, polypropylene: 20 parts, amine-modified SEBS: 10 parts, filler: 1.5 parts, amide lubricant: 1.8 parts, and antioxidant 0.5 parts; The amide lubricant is obtained by mixing erucamide and didodecyl hydroxystearamide in a mass ratio of 1:0.8; The filler is a composite titanium dioxide nanosheet, and the preparation includes the following steps: (1) 40 mL of anhydrous ethanol, 10 mL of tetrabutyl titanate, 1.2 mL of hydrogen fluoride, and 355 mg of copper nitrate trihydrate were stirred for 30 min, transferred to a hydrothermal kettle, kept warm at 182 °C for 110 min, centrifuged, washed, dried, and ground to obtain copper-doped titanium dioxide nanosheets; (2) 80 mg of epigallocatechin gallate and 20 mL of tris(hydroxymethyl)methylaminomethane solution were mixed, 80 mg of ε-polylysine and 20 mL of tris(hydroxymethyl)methylaminomethane solution were added, and 50 mg of copper-doped titanium dioxide nanosheets were added. The mixture was kept at 39 ° C for 22 h, washed, dried, and ground to obtain modified titanium dioxide nanosheets. (3) 1 g of modified titanium dioxide nanosheets and 20 mL of sodium acetate buffer were mixed, the pH was adjusted to 7.5, 0.8 g of modified carboxymethyl chitosan and 20 mL of sodium acetate buffer were added, the pH was adjusted to 7.5, and the mixture was shaken at 39 °C for 3 h, centrifuged, filtered, and freeze-dried to obtain composite titanium dioxide nanosheets; The preparation of the modified carboxymethyl chitosan comprises the following steps: Mix 0.2 g of carboxymethyl chitosan and 20 mL of deionized water, stir at 25 ° C for 50 minutes, heat to 83 ° C in an oil bath and keep warm for 20 minutes, add a mixture of 20 mL of ethanol, 3 mg of stearic acid, 2 mg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, and 2 mg of N-hydroxysuccinimide, continue to keep warm for 8 hours, cool, stir at 25 ° C for 22 hours, precipitate with ethanol, centrifuge, wash, dialyze in 50 mL of deionized water for 72 hours, and freeze-dry to obtain modified carboxymethyl chitosan.

[0028] Comparative Example 1: Example 1 was used as a control group, amine-modified SEBS was not prepared, and other processes were normal.

[0029] Comparative Example 2: Example 1 was used as the control group, without adding didohydroxystearamide, and the other processes were normal.

[0030] Comparative Example 3: Taking Example 4 as the control group, copper-doped titanium dioxide nanosheets were used to replace the composite titanium dioxide nanosheets, and the other processes were normal.

[0031] Comparative Example 4: Taking Example 4 as the control group, carboxymethyl chitosan was used to replace the modified carboxymethyl chitosan, and the other processes were normal.

[0032] In the examples and comparative examples, the antioxidant was prepared by mixing antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.

[0033] Source of raw materials (for example only): SEBS7551: Li Changrong Chemical Industry Co., Ltd.; Propylene elastomer 6202FL: ExxonMobil; Vinyl elastomer C5070D: Sabic; Polypropylene MH7900: LG Chem; Amine-modified SEBSMP10: Asahi Kasei; Titanium dioxide R103: Chemours; Distearate S330: Shanghai Sonnar New Materials Co., Ltd.; Carboxymethyl chitosan C9400: Beijing Solebold Technology Co., Ltd.; Antioxidant 1010S67391, Antioxidant 168S31114: Shanghai Yuanye Biotechnology Co., Ltd. Technology Co., Ltd.; erucamide E107867, tetrabutyl titanate T104105, epigallocatechin gallate E107404, tris(hydroxymethyl)methylaminomethane T274250, ε-polylysine P303210, sodium acetate buffer S493145, stearic acid S108289, 1-ethyl-(3-dimethylaminopropyl)carbodiimide E106172, N-hydroxysuccinimide H109330: Aladdin reagent; anhydrous ethanol, hydrogen fluoride, copper nitrate trihydrate, analytical grade, commercially available.

[0034] Performance test: The performance test was performed on the inner pad materials prepared in the examples and comparative examples: Total migration of isooctane: Tested according to GB4806.7, incubated at 20°C for 2 days; Staining: 5 people judged, and the average value was calculated. The grades are: 0: no color difference to the naked eye; 1: very slight staining, hardly noticeable; 2: easily observable staining; 3: clearly observable staining. Incubated at 37°C for 20 days, with the sample inverted; Antibacterial activity: Escherichia coli was used as the test strain, and the samples were washed 10 times with water and dried, and then tested using the plate method. The test results are shown in Table 1. Opening torque: The bottle cap torque tester was used for testing. The test results are shown in Table 2. Table 1

[0035] Table 2

[0036] The present invention provides a grease-resistant food-grade TPE inner pad material and a preparation method thereof. By optimizing the formula and process, a grease-resistant food-grade TPE inner pad material is prepared that is safe, has excellent antibacterial properties, and has good adhesion to bottle caps. By controlling the raw material ratio, the material has moderate resilience to simultaneously take into account sealing and opening torque. The material has high economic value and practical significance. / in the table indicates untested.

[0037] Comparing Example 1 with Comparative Example 1, amine-modified SEBS is introduced into the inner liner material. The amino component in the amine-modified SEBS is utilized to increase the adaptability of the inner liner material to different coatings of the bottle cap and expand its scope of use. At the same time, the tolerance to grease or isooctane is enhanced and the probability of the product being stained is reduced. Compared with the anhydride-modified inner liner material, the introduction of amine-modified SEBS has a better odor and reduces the impact on the taste of the contents.

[0038] Comparing Example 1 with Comparative Example 2, erucamide and didodecyl hydroxystearamide were selected as the amide lubricant. The precipitation speed of erucamide was fast, ensuring the initial screw-in distance of the bottle cap, while the precipitation of didodecyl hydroxystearamide was relatively slow, ensuring the long-term stability of the opening torque. At the same time, the introduction of a large number of hydrophilic groups in didodecyl hydroxystearamide can prevent oily substances from entering the inner pad material, improve the oil resistance of the inner pad material, and synergistically reduce the probability of the product being stained.

[0039] Example 4 was compared with Comparative Examples 3 and 4. To further improve the mechanical strength and antibacterial properties of the inner pad material, titanium dioxide was selected as a filler. To improve the antibacterial properties of titanium dioxide, copper-doped titanium dioxide nanosheets were prepared by an in-situ hydrothermal method to improve their activity. To improve the bonding strength between the copper-doped titanium dioxide nanosheets and the inner pad material base material and to improve the uniformity of the copper-doped titanium dioxide nanosheets dispersed in the inner pad material, the copper-doped titanium dioxide nanosheets were immersed in a tris(hydroxymethyl)methylaminomethane solution containing epigallocatechin gallate and ε-polylysine by liquid phase deposition. A phenolamine layer is prepared on the surface of the inner pad, in which the introduction of epigallocatechin gallate and ε-polylysine has a green antibacterial effect and improves food safety. In order to further synergistically improve the oil resistance of the inner pad material, the electrostatic interaction between the inner pad and the modified carboxymethyl chitosan is enhanced by controlling the process parameters. The modified carboxymethyl chitosan is acylated with stearic acid on the amino group of the carboxymethyl chitosan using 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide as catalysts. By controlling the amount of introduction, the oil resistance and antibacterial properties of the inner pad material are synergistically improved, thereby greatly expanding the scope of use of the inner pad material.

[0040] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structural transformations made using the present invention specification under the inventive concept of the present invention, or any direct / indirect application in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A grease-resistant food-grade TPE inner pad material, characterized in that: The composition of the TPE inner pad material is, in parts by mass: SEBS: 20-40 parts, propylene elastomer: 10-30 parts, vinyl elastomer: 20-40 parts, polypropylene: 10-20 parts, amine-modified SEBS: 3-10 parts, filler: 0.5-1.5 parts, amide lubricant: 1-3 parts, and antioxidant 0.1-0.5 parts.

2. The grease-resistant food-grade TPE inner pad material according to claim 1, characterized in that: The comonomer of the propylene-based elastomer is ethylene, wherein the vinyl content is 5-20%.

3. The grease-resistant food-grade TPE inner pad material according to claim 1, characterized in that: The comonomer of the vinyl elastomer is octene, and the copolymerization form is block type, wherein the octene content is 20-30%.

4. The grease-resistant food-grade TPE inner pad material according to claim 1, characterized in that: The amide lubricant is prepared by mixing erucamide and didodecyl hydroxystearamide in a mass ratio of (0.5-1): (0.6-1.7).

5. The grease-resistant food-grade TPE inner pad material according to claim 1, characterized in that: The filler is rutile titanium dioxide.

6. The grease-resistant food-grade TPE inner pad material according to claim 1, characterized in that: The filler is a composite titanium dioxide nanosheet, and the preparation includes the following steps: (1) Anhydrous ethanol, tetrabutyl titanate, hydrogen fluoride, and copper nitrate trihydrate were stirred for 20-30 minutes, transferred to a hydrothermal kettle, kept at 178-182°C for 110-130 minutes, centrifuged, washed, dried, and ground to obtain copper-doped titanium dioxide nanosheets; (2) epigallocatechin gallate and tris(hydroxymethyl)methylaminomethane solution were mixed, ε-polylysine and tris(hydroxymethyl)methylaminomethane solution were added, copper-doped titanium dioxide nanosheets were added, and the mixture was kept at 35-39°C for 22-24 hours, washed, dried, and ground to obtain modified titanium dioxide nanosheets; (3) The modified titanium dioxide nanosheets and sodium acetate buffer solution were mixed, the pH was adjusted to 7.5, and a mixture of modified carboxymethyl chitosan and sodium acetate buffer solution was added, the pH was adjusted to 7.5, and the mixture was shaken at 35-39°C for 3-4 hours, centrifuged, filtered, and freeze-dried to obtain composite titanium dioxide nanosheets.

7. The grease-resistant food-grade TPE inner pad material according to claim 6, characterized in that: The mass ratio of the modified titanium dioxide nanosheets to the modified carboxymethyl chitosan is 1:0.

8.

8. The grease-resistant food-grade TPE inner pad material according to claim 6, characterized in that: The preparation of the modified carboxymethyl chitosan comprises the following steps: Carboxymethyl chitosan and deionized water are mixed, stirred at 18-25°C for 50-70 minutes, heated to 77-83°C and kept warm in an oil bath for 20-30 minutes, a mixture of ethanol, stearic acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide is added, and the mixture is kept warm for 6-8 hours. The mixture is cooled, stirred at 18-25°C for 22-24 hours, precipitated with ethanol, centrifuged, washed, dialyzed in deionized water for 72 hours, and freeze-dried to obtain modified carboxymethyl chitosan.

9. The method for preparing a grease-resistant food-grade TPE inner pad material according to any one of claims 1 to 8, characterized in that: The steps include: SEBS, propylene elastomer, vinyl elastomer, polypropylene, amine-modified SEBS, filler, amide lubricant, and antioxidant are sequentially added into a high-speed mixer, mixed, and then extruded and granulated to obtain a grease-resistant food-grade TPE inner pad material.

10. The method for preparing a grease-resistant food-grade TPE inner pad material according to claim 9, characterized in that: Extrusion temperature: 170-220℃.

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