High-temperature-resistant food packaging film and preparation method thereof

Abstract

The invention relates to the technical field of packaging, in particular to a high-temperature-resistant food packaging film and a preparation method thereof, and the high-temperature-resistant food packaging film comprises modified polypropylene, modified talcum powder, gamma-aminopropyltriethoxysilane and erucyl amide. The beta crystal form modified polypropylene with a hexagonal spherical crystal structure is formed by inducing heterogeneous nucleation of polypropylene, keeps good toughness under a long-term low-temperature condition, and does not embrittle or crack to expose contents. Maleic anhydride grafting of the modified talcum powder is entangled with a modified polypropylene molecular chain to prevent movement of the molecular chain, so that the modified polypropylene is prevented from being converted from a beta crystal form to an alpha crystal form. And gamma-aminopropyltriethoxysilane is combined with the modified talcum powder to form a silane terminal-talcum powder-maleic anhydride grafted-modified polypropylene molecular chain composite structure, the alpha crystal nucleation site of the modified talcum powder is completely covered, and the hindering effect of the modified talcum powder is further enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the packaging technical field, specifically to a high-temperature-resistant food packaging film and a preparation method thereof. BACKGROUND

[0002] At present, polypropylene or polyethylene materials are widely used to make high-temperature-resistant food packaging films due to their heat resistance and stable properties, and can package high-temperature hot pot seasoning oily liquid. However, only the problem of stability at high temperature is focused on, and whether the material properties can still meet the requirements in different environments during use is not considered. After being opened, the hot pot seasoning that is not used up is generally placed in the refrigerator for cold storage and preservation, and is long-term in a low-temperature environment. The plastic food film will become hard and brittle, and even crack and expose the contents, which is not conducive to food safety and human health. SUMMARY

[0003] (1) Technical problem to be solved

[0004] The purpose of the present application is to provide a high-temperature-resistant food packaging film and a preparation method thereof, which can maintain good toughness in a long-term low-temperature environment, prevent the plastic food film from becoming hard and brittle, and even cracking and exposing the contents, and ensure food safety and human health.

[0005] (2) Technical scheme

[0006] To achieve the above-mentioned purpose, on the one hand, the present application provides a high-temperature-resistant food packaging film, the raw materials of which include, by weight: modified polypropylene 200-300 parts, modified talcum powder 20-30 parts, gamma-aminopropyl triethoxysilane 0.2-0.9 parts, and erucamide 0.2-0.9 parts.

[0007] The crystal form of the modified polypropylene is a β crystal form of a hexagonal spherical crystal structure.

[0008] The modified polypropylene is physically blended with polypropylene and N,N'-naphthalene oxamide. The rigid benzene ring structure of N,N'-naphthalene oxamide acts as a heterogeneous nucleation point, promotes the ordered arrangement of polypropylene molecular chains, and improves the crystallinity of β crystals.

[0009] The talcum powder-maleic anhydride grafting agent on the surface of the modified talcum powder is generated by esterification and acid-base reaction of the carboxyl group of maleic anhydride with the silicon hydroxyl group and magnesium hydroxyl group on the surface of the talcum powder.

[0010] Further, the preparation method of the modified polypropylene comprises the following steps:

[0011] S11. Polypropylene particles, N,N'-naphthalene oxamide, antioxidant 1010, and calcium stearate are pre-mixed in a high-speed mixer, the mixing time is 1-1.5 h, and a pre-mixture is obtained;

[0012] S12. The premix is transferred to a twin-screw extruder, melt blended at a temperature of 180-220℃ for 3h, extruded and granulated to obtain the modified polypropylene.

[0013] Further, the premix raw material is composed of 92-95 parts of polypropylene particles, 0.4-0.5 parts of N,N'-dinaftyl oxamide, 0.2 parts of antioxidant 1010, and 0.1 parts of calcium stearate.

[0014] Further, the preparation method of the modified talc powder comprises the following steps:

[0015] S21. The talc powder is dried in a constant temperature drying oven at 105℃ for 1.5-2h to obtain talc powder without adsorbed water;

[0016] S22. The talc powder without adsorbed water, maleic anhydride, and dicumyl peroxide are premixed in a high-speed mixer for 10-15min to obtain a mixture;

[0017] S23. The mixture is transferred to a twin-screw extruder, reacted at a temperature of 160-180℃ for 5-10min, cooled, crushed by a crusher, and sieved to obtain the modified talc powder.

[0018] Further, the mixture raw material is composed of 100-110 parts of talc powder, 1-5 parts of maleic anhydride, and 0.1-0.5 parts of dicumyl peroxide.

[0019] On the other hand, based on the same inventive concept, the application also provides a preparation method of a high-temperature-resistant food packaging film, which is applied to the high-temperature-resistant food packaging film and comprises the following steps:

[0020] S31. Modified polypropylene is prepared;

[0021] S32. Modified talc powder is prepared;

[0022] S33. The modified polypropylene, the modified talc powder, γ-aminopropyl triethoxysilane, and erucamide are put into a twin-screw extruder, melt blended for 3h, extruded through an annular die, and cooled by a cooling air ring to obtain the high-temperature-resistant food packaging film.

[0023] Further, the temperature condition of the melt blending is 180-200℃.

[0024] Further, the control condition of the extrusion through the annular die is a blow-up ratio (BUR) of 2-4:1 and a pulling speed of 10-15m / min.

[0025] The mechanism of the above raw material components is as follows:

[0026] The modified polypropylene is a material with good thermal stability. By physically blending polypropylene with N,N'-dinaftyl oxamide, the rigid benzene ring structure of N,N'-dinaftyl oxamide can act as a heterogeneous nucleation point, promote the ordered arrangement of polypropylene molecular chains, and increase the crystallinity of the β crystal form. N,N'-dinaftyl oxamide has a stable conjugated structure in the polypropylene system, and the hydroxyl group can form hydrogen bonds. The two factors work together to stabilize the polypropylene segment, promote the crystallization process, and increase the nucleation ability. In addition, the side chain of N,N'-dinaftyl oxamide contains a conjugated π bond, which not only stabilizes the polypropylene segment, but also provides a site for crystallization and nucleation. The hydroxyl functional group can form hydrogen bonds in the amorphous phase, thereby promoting the formation of more stable spherulites of polypropylene. The β crystal form of the modified polypropylene is a hexagonal spherulite structure, which enhances the tensile strength and maintains good toughness even at an environmental temperature of -20°C.

[0027] The β crystal form is a thermodynamically metastable crystal form, while the α crystal form has a higher crystallinity and the polypropylene molecular chains are more closely arranged. Therefore, the α crystal form has better thermodynamic stability. Under normal circumstances, the β crystal form will gradually transform into the α crystal form. The α crystal form has poor toughness, and if this change is not prevented, the food film will become hard and brittle at low temperatures, increasing the risk of content exposure, which is not conducive to food safety and human health.

[0028] Talc itself is a lubricant, and its surface contains silicon hydroxyl groups (Si-OH) and magnesium hydroxyl groups (Mg-OH). These active groups can react with the carboxyl groups (-COOH) of maleic anhydride (MAH) as follows: esterification reaction with silicon hydroxyl groups, reaction equation: Si-OH + MAH→Si-O-CO-CH=CH-COOH + H2O; acid-base reaction with magnesium hydroxyl groups, reaction equation: Mg-OH + MAH→Mg-O-CO-CH=CH-COOH + H2O. Through esterification and acid-base reactions, talc-maleic anhydride grafts are generated on the surface of modified talc. The olefin chain (-CH=CH-) of maleic anhydride entangles with the molecular chain of modified polypropylene, preventing the movement of molecular chains and hindering the transformation of the crystal form of modified polypropylene from β crystal to α crystal.

[0029] γ-aminopropyl triethoxysilane is an organic silicon compound with a special structure. The silanol forms a stable Si-O-Si covalent bond with the silicon hydroxyl groups on the surface of the modified talc. A complex structure of silane end-talc-maleic anhydride graft-modified polypropylene molecular chain is formed, completely covering the α crystal nucleation sites of the modified talc, further strengthening the hindering effect of the modified talc on the transformation of the crystal form of modified polypropylene from β crystal to α crystal.

[0030] The surface of the modified polypropylene in the beta crystal form is rough, and the erucamide migrates to the surface of the modified polypropylene during the processing to form a monomolecular lubricating layer, thereby improving the smoothness of the film.

[0031] (3) Beneficial effects

[0032] Compared with the prior art, the beneficial effects of the present application are:

[0033] 1. N,N'-dinaphthyl oxamide induces heterogeneous nucleation to form the beta crystal form of the modified polypropylene, and under long-term low-temperature conditions, the hexagonal spherulite structure enables the modified polypropylene to maintain good toughness and not to be brittle and cracked to expose the contents, thereby ensuring food safety and human health.

[0034] 2. The maleic anhydride grafting of the modified talc powder is entangled with the molecular chains of the modified polypropylene, thereby preventing the movement of the molecular chains and hindering the conversion of the beta crystal form of the modified polypropylene into the alpha crystal form.

[0035] 3. The composite structure of the silane end-talc-maleic anhydride graft-modified polypropylene molecular chain completely covers the alpha crystal nucleation sites of the modified talc powder, thereby further strengthening the hindering effect of the modified talc powder on the crystal form conversion. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The beta crystal PLM image of the modified polypropylene in Example 1 of the present application. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0038] Example 1

[0039] The present embodiment discloses a high-temperature-resistant food packaging film, and the raw materials include, by weight fraction, 200 parts of modified polypropylene, 20 parts of modified talc powder, 0.2 parts of γ-aminopropyl triethoxysilane, and 0.2 parts of erucamide.

[0040] The crystal form of the modified polypropylene is the beta crystal form of the hexagonal spherulite structure. The beta crystal structure of the modified polypropylene is as shown in Figure 1 .

[0041] The modified polypropylene is physically blended with polypropylene and N,N'-dinaphthyl oxamide. The rigid benzene ring structure of the N,N'-dinaphthyl oxamide serves as a heterogeneous nucleation point, promotes the ordered arrangement of the polypropylene molecular chains, and improves the crystallinity of the beta crystal.

[0042] The talc-maleic anhydride grafted product on the surface of the modified talc is produced by esterification and acid-base reaction between the carboxyl group of maleic anhydride and the silanol group and magnesium hydroxyl group on the surface of the talc.

[0043] The rigid benzene ring structure of N,N'-dinaphthyloxamide acts as a heterogeneous nucleation site, promoting the orderly arrangement of polypropylene molecular chains and promoting β-crystal crystallization. N,N'-dinaphthyloxamide possesses a stable conjugated structure in the polypropylene system, and the hydroxyl groups are capable of forming hydrogen bonds. These two factors work together to stabilize the polypropylene chain segments and enhance nucleation ability. Furthermore, the conjugated π bonds in the side chains of N,N'-dinaphthyloxamide not only stabilize the polypropylene segments but also provide sites for crystallization nucleation. The hydroxyl functional groups can form hydrogen bonds in the amorphous phase, further stabilizing the spherulites formed by the polypropylene. The resulting β-crystal-modified polypropylene has a hexagonal spherulite structure, enhancing tensile strength at break and maintaining good toughness even at ambient temperatures of -20°C. Because the β-crystal is a thermodynamically metastable form, while the α-crystal is more thermodynamically stable, the β-crystal generally transitions to the α-crystal.

[0044] The silanol and magnesium hydroxyl active groups on the talc surface undergo esterification and acid-base reactions with the carboxyl groups of maleic anhydride, forming a talc-maleic anhydride graft on the surface of the modified talc. The olefin chains of maleic anhydride entangle with the modified polypropylene molecular chains, preventing their movement and hindering the crystal transformation of the modified polypropylene from β to α. The silanols of γ-aminopropyltriethoxysilane bind to the silanols on the surface of the modified talc, forming a composite structure of silane end-talc-maleic anhydride graft-modified polypropylene molecular chains. This structure completely covers the α-crystal nucleation sites of the modified talc, further strengthening the modified talc's ability to inhibit the crystal transformation from β to α.

[0045] Furthermore, the preparation method of the modified polypropylene comprises the following steps:

[0046] S11 polypropylene particles, N, N'- dinaphthyl oxamide, antioxidant 1010 and calcium stearate were premixed in a high-speed mixer, the mixing time was 1 to 1.5h to obtain a premix;

[0047] S12. The premix is ​​transferred to a twin-screw extruder, melt-blended at a temperature of 180-220°C for 3 hours, and extruded into pellets to obtain modified polypropylene.

[0048] Furthermore, the weight ratio of the premix raw materials is as follows: 92-95 parts of polypropylene particles, 0.4-0.5 parts of N,N'-dinaphthyl oxalamide, 0.2 parts of antioxidant 1010, and 0.1 parts of calcium stearate.

[0049] Further, the preparation method of the modified talc powder comprises the following steps:

[0050] S21. Dry the talc powder in a constant temperature drying oven at 105℃ for 1.5-2h to obtain talc powder without adsorbed water;

[0051] S22. Pre-mix the talc powder without adsorbed water, maleic anhydride and dicumyl peroxide in a high-speed mixer for 10-15min to obtain a mixture;

[0052] S23. Transfer the mixture to a twin-screw extruder, react at a temperature of 160-180℃ for 5-10min, cool, crush with a crusher and sieve to obtain the modified talc powder.

[0053] Further, the weight ratio of the raw materials of the mixture is composed of talc powder 100-110 parts, maleic anhydride 1-5 parts and dicumyl peroxide 0.1-0.5 parts.

[0054] On the other hand, based on the same inventive concept, the application further provides a preparation method of a high-temperature-resistant food packaging film, which is applied to the high-temperature-resistant food packaging film and comprises the following steps:

[0055] S31. Prepare a modified polypropylene;

[0056] S32. Prepare a modified talc powder;

[0057] S33. Put the modified polypropylene, the modified talc powder, γ-aminopropyl triethoxysilane and erucamide into a twin-screw extruder, melt blend for 3h, extrude through an annular die, and cool with a cooling air ring to shape to obtain the high-temperature-resistant food packaging film.

[0058] Further, the temperature condition of the melt blending is 180-200℃.

[0059] Further, the control condition of the extrusion through the annular die is a blow-up ratio (BUR) of 2-4:1 and a pulling speed of 10-15m / min.

[0060] It should be noted that the surface of the modified polypropylene in the β crystal form is relatively rough, and the erucamide will migrate to the surface of the modified polypropylene during the processing to form a monomolecular lubricating layer, thereby improving the smoothness of the film.

[0061] Example 2

[0062] The embodiment discloses a high-temperature-resistant food packaging film, and the raw materials include, by weight fraction, modified polypropylene 300 parts, modified talc powder 30 parts, γ-aminopropyl triethoxysilane 0.9 parts and erucamide 0.9 parts; and the crystal form of the modified polypropylene is a β crystal form of a hexagonal spherical crystal structure.

[0063] The modified polypropylene and the modified talcum powder of the embodiment are prepared according to the method of Example 1. The modified polypropylene and the modified talcum powder of the embodiment are prepared according to the method of Example 1.

[0064] Example 3

[0065] The embodiment discloses a high-temperature-resistant food packaging film, raw materials of which include, by weight: 250 parts of modified polypropylene, 25 parts of modified talcum powder, 0.5 part of γ-aminopropyl triethoxysilane and 0.5 part of erucamide; the modified polypropylene is in a β crystal form of a hexagonal spherical crystal structure.

[0066] The modified polypropylene and the modified talcum powder of the embodiment are prepared according to the method of Example 1. The modified polypropylene and the modified talcum powder of the embodiment are prepared according to the method of Example 1.

[0067] Example 4

[0068] The embodiment discloses a high-temperature-resistant food packaging film, raw materials of which include, by weight: 199 parts of modified polypropylene, 19 parts of modified talcum powder, 0.1 part of γ-aminopropyl triethoxysilane and 0.1 part of erucamide; the modified polypropylene is in a β crystal form of a hexagonal spherical crystal structure.

[0069] The modified polypropylene and the modified talcum powder of the embodiment are prepared according to the method of Example 1. The modified polypropylene and the modified talcum powder of the embodiment are prepared according to the method of Example 1.

[0070] Example 5

[0071] The embodiment is different from Example 1 in that N,N'-dinaphthyl oxamide is not added in the preparation of the modified polypropylene.

[0072] The embodiment discloses a high-temperature-resistant food packaging film, raw materials of which include, by weight: 200 parts of modified polypropylene, 20 parts of modified talcum powder, 0.2 part of γ-aminopropyl triethoxysilane and 0.2 part of erucamide; the modified polypropylene is in a β crystal form of a hexagonal spherical crystal structure.

[0073] Further, the preparation method of the modified polypropylene comprises the following steps:

[0074] S11. Polypropylene particles, antioxidant 1010 and calcium stearate are premixed in a high-speed mixer, and the mixing time is 1-1.5 h to obtain a premix;

[0075] S12. The premix is transferred to a double-screw extruder, and is melt blended at a temperature of 180-220 DEG C for 3 h, and is extruded and granulated to obtain the modified polypropylene.

[0076] Further, the premix raw material weight ratio is composed of polypropylene particles 92-95 parts, antioxidant 101 0.2 parts, calcium stearate 0.1 part.

[0077] The preparation method of the modified talc powder of the embodiment is consistent with that of Embodiment 1. The preparation method of the high-temperature-resistant food packaging film of the embodiment is consistent with that of Embodiment 1.

[0078] Embodiment 6

[0079] The difference between the embodiment and Embodiment 1 is that maleic anhydride is not added when the modified talc powder is prepared.

[0080] The embodiment discloses a high-temperature-resistant food packaging film, raw materials of which include, by weight: modified polypropylene 200 parts, modified talc powder 20 parts, γ-aminopropyl triethoxysilane 0.2 parts, and erucamide 0.2 parts; the modified polypropylene has a hexagonal spherical crystal structure of a β crystal form.

[0081] Further, the preparation method of the modified talc powder includes the following steps:

[0082] S21. The talc powder is dried in a constant-temperature drying box at 105°C for 1.5-2 hours to obtain talc powder without adsorbed water;

[0083] S22. The talc powder without adsorbed water and dicumyl peroxide are premixed in a high-speed mixer for 10-15 minutes to obtain a mixture.

[0084] S23. The mixture is transferred to a twin-screw extruder and reacted at a temperature of 160-180°C for 5-10 minutes, cooled, crushed by a crusher, and sieved to obtain the modified talc powder.

[0085] Further, the mixture raw material weight ratio is composed of talc powder 100-110 parts and dicumyl peroxide 0.1-0.5 parts.

[0086] The preparation method of the modified polypropylene of the embodiment is consistent with that of Embodiment 1. The preparation method of the high-temperature-resistant food packaging film of the embodiment is consistent with that of Embodiment 1.

[0087] Comparative Example 1

[0088] The difference between the comparative example and Embodiment 1 is that the modified polypropylene is not contained.

[0089] The comparative example discloses a high-temperature-resistant food packaging film, raw materials of which include, by weight: modified talc powder 20 parts, γ-aminopropyl triethoxysilane 0.2 parts, and erucamide 0.2 parts.

[0090] The preparation method of the modified talc powder in this comparative example is the same as that in Example 1. The preparation method of a high-temperature resistant food packaging film in this comparative example is the same as that in Example 1.

[0091] Comparative Example 2

[0092] The difference between this comparative example and Example 1 is that the comparative example does not contain modified talc.

[0093] This comparative example discloses a high-temperature resistant food packaging film, the raw materials of which include, by weight, 200 parts of modified polypropylene, 0.2 parts of γ-aminopropyltriethoxysilane, and 0.2 parts of erucamide; the crystal form of the modified polypropylene is a β-crystal form with a hexagonal spherulite structure.

[0094] The preparation method of the modified polypropylene in this comparative example is the same as that in Example 1. The preparation method of a high-temperature resistant food packaging film in this comparative example is the same as that in Example 1.

[0095] Comparative Example 3

[0096] The difference between this comparative example and Example 1 is that γ-aminopropyltriethoxysilane is not contained.

[0097] This comparative example discloses a high-temperature resistant food packaging film, the raw materials of which include, by weight, 200 parts of modified polypropylene, 20 parts of modified talc, and 0.2 parts of erucamide; the crystal form of the modified polypropylene is a β-crystal form with a hexagonal spherulite structure.

[0098] The preparation methods of the modified polypropylene and modified talc in this comparative example are the same as those in Example 1. The preparation method of a high-temperature resistant food packaging film in this comparative example is the same as that in Example 1.

[0099] Test Example 1

[0100] The polypropylene β crystal content of the high-temperature resistant food packaging films prepared in Examples 1-6 and Comparative Examples 1-3 was tested at 0 h, 24 h, and 72 h, respectively. The test results are shown in Table 1.

[0101] Table 1 Detection of polypropylene β crystal content in food packaging film

[0102] 0h 24h 72h Example 1 78~82% 78~82% 74~80% Example 2 78~81% 78~80% 75~80% Example 3 83~85% 83~85% 81~83% Example 4 70~75% 70~74% 69~74% Example 5 10~15% 5~8% 5~7% Example 6 70~73% 65~70% 63~67% Comparative Example 1 0% 0% 0% Comparative Example 2 65~69% 55~60% 40~45% Comparative Example 3 70~73% 65~70% 62~65%

[0103] Test Example 2

[0104] The high-temperature resistant food packaging films prepared in Examples 1-6 and Comparative Examples 2-3 were placed at -20°C and kept warm for 0 h, 24 h, and 72 h to test the elongation at break. The testing method is prior art and will not be elaborated on here. The test results are shown in Table 2.

[0105] Table 2 Elongation at break of food packaging film

[0106] 0h 24h 72h Example 1 440~480% 440~480% 440~480% Example 2 440~480% 430~470% 430~470% Example 3 450~500% 450~500% 450~500% Example 4 400~450% 400~440% 400~440% Example 5 100~150% 50~80% 50~70% Example 6 400~450% 390~430% 380~420% Comparative Example 2 380~420% 350~400% 250~300% Comparative Example 3 420~450% 400~440% 380~420%

[0107] Combining the data in Tables 1 and 2, Example 3 of the present invention represents the optimal ratio, maintaining a balanced β-crystal content in the polypropylene and exhibiting good toughness at -20°C. Comparing Comparative Example 2 with Example 1, the addition of modified talc in the present invention does indeed hinder the transformation of the modified polypropylene from the β- to α-crystal form. Comparing Comparative Example 3 with Example 1, the γ-aminopropyltriethoxysilane of the present invention further hinders the transformation of the modified polypropylene from the β- to α-crystal form.

[0108] Finally, it should be noted that although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high temperature resistant food packaging film, characterized in that: The raw materials include, by weight: 200-300 parts of modified polypropylene, 20-30 parts of modified talc, 0.2-0.9 parts of γ-aminopropyltriethoxysilane, and 0.2-0.9 parts of erucamide; The modified polypropylene has a β-crystal structure with a hexagonal spherical crystal structure. The modified polypropylene is prepared by physically blending polypropylene with N,N'-dinaphthyl oxalamide. The rigid benzene ring structure of N,N'-dinaphthyl oxalamide serves as a heterogeneous nucleation point to promote the orderly arrangement of polypropylene molecular chains and improve the crystallinity of β crystals. The talc-maleic anhydride grafted compound on the surface of the modified talc is produced by esterification and acid-base reaction between the carboxyl group of maleic anhydride and the silanol group and magnesium hydroxyl group on the surface of the talc.

2. A high temperature resistant food packaging film according to claim 1, characterized in that: The preparation method of the modified polypropylene comprises the following steps: S11 polypropylene particles, N, N'- dinaphthyl oxalamide, antioxidant 1010 and calcium stearate were premixed in a high-speed mixer, the mixing time was 1 to 1.5h to obtain a premix; S12. The premix is ​​transferred to a twin-screw extruder, melt-blended at a temperature of 180-220°C for 3 hours, and extruded into pellets to obtain modified polypropylene.

3. A high temperature resistant food packaging film according to claim 2, characterized in that: The weight ratio of the raw materials of the premix is: 92-95 parts of polypropylene particles, 0.4-0.5 parts of N,N'-dinaphthyl oxalamide, 0.2 parts of antioxidant 1010, and 0.1 parts of calcium stearate.

4. The high temperature resistant food packaging film according to claim 1, characterized in that: The preparation method of the modified talc comprises the following steps: S21. The talc was dried in a constant temperature drying oven at 105 ° C for 1.5 to 2 h to obtain talc without adsorbed water; S22. The talc without adsorbed water, maleic anhydride, dicumyl peroxide were premixed in a high-speed mixer, the mixing time was 10 to 15min to obtain a mixture; S23. The mixture is transferred to a twin-screw extruder, reacted at a temperature of 160-180° C. for 5-10 minutes, cooled, crushed with a grinder, and sieved to obtain modified talc powder.

5. The high temperature resistant food packaging film according to claim 4, characterized in that: The weight ratio of the raw materials of the mixture is: 100-110 parts of talc powder, 1-5 parts of maleic anhydride, and 0.1-0.5 parts of dicumyl peroxide.

6. A method for preparing a high-temperature resistant food packaging film, which is used to prepare the high-temperature resistant food packaging film according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: S31. Preparation of modified polypropylene; S32. Preparation of modified talc; S33. Modified polypropylene, modified talc, γ-aminopropyltriethoxysilane, and erucamide are placed into a twin-screw extruder, melt-blended for 3 hours, extruded through an annular die, and shaped using a cooling air ring to obtain a high-temperature resistant food packaging film.

7. The method for preparing a high temperature resistant food packaging film according to claim 6, characterized in that: The temperature condition of the melt blending is 180-200°C.

8. The method for preparing a high temperature resistant food packaging film according to claim 6, characterized in that: The control conditions for the extrusion through the annular die are a blow-up ratio (BUR) of 2-4:1 and a pulling rate of 10-15 m / min.

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