High-temperature-resistant packaging film for oven and preparation method

Abstract

The high-temperature-resistant packaging film is a co-extrusion film and comprises a high-temperature-resistant outer layer, a toughening core layer and a high-temperature-resistant heat sealing layer which are sequentially stacked from outside to inside, the high-temperature-resistant outer layer comprises at least two high-temperature-resistant unit layers, and the toughening core layer comprises at least two toughening unit layers; the raw materials of the high-temperature-resistant unit layer and the toughening unit layer comprise homopolymerized nylon, toughening nylon, an elastomer and a high-temperature-resistant master batch; the high-temperature-resistant heat-sealing layer is prepared from the following raw materials: homopolymerized nylon, heat-sealing nylon and high-temperature-resistant master batch; the high-temperature-resistant master batch comprises nylon 6, a heat-resistant agent and an antioxidant; and the heat-resistant agent is an N-(4-fluorophenyl) maleimide-styrene copolymer and an N-(4-carboxyl phenyl) maleimide-triallyl isocyanurate copolymer. The packaging film is good in high temperature resistance, the content of homopolymerized nylon in each layer is sequentially reduced from outside to inside, the packaging film with temperature difference is formed, and the heat sealing layer is prevented from being burnt; the compound heat-resistant agent has excellent temperature resistance, compatibility and processability.

Description

Technical Field

[0001] This invention relates to the field of packaging film technology, specifically to a high-temperature resistant packaging film for ovens and its preparation method. Background Technology

[0002] High-temperature resistant packaging film is used to seal or wrap seasoned foods such as chicken, duck, fish, meat, potatoes, and beans that require cooking, while leaving vents. These are then heated in an oven at high temperatures for a period of time to obtain cooked food. Therefore, the high-temperature resistant packaging film needs to withstand temperatures above 120°C. In addition, the high-temperature resistant packaging film must be strong enough to withstand scratches and punctures from food (such as chicken bones, potato wedges, and hard beans) to prevent damage during handling or cooking.

[0003] Materials used for high-temperature resistant film production include PET, CPP, and PA, but PET is less puncture resistant than PA, and CPP is relatively hard and brittle, making it prone to breakage when impacted by sharp objects. Therefore, improvements are needed to enhance high-temperature resistant packaging films. Summary of the Invention

[0004] One of the objectives of this invention is to overcome the deficiencies in the prior art and provide a high-temperature resistant packaging film for ovens. The raw materials of each layer are optimized by compounding homopolymer nylon with high-temperature resistant masterbatch to improve the overall high-temperature resistance of the packaging film. The content of homopolymer nylon in each layer decreases sequentially from the outside to the inside, forming a packaging film with temperature difference to prevent the heat-sealing layer from being scalded. The heat-resistant agent, compounded from N-(4-fluorophenyl)maleimide-styrene copolymer and N-(4-carboxyphenyl)maleimide-tracelyl isocyanurate copolymer, optimizes the temperature resistance of the packaging film, improves compatibility, and enhances processability and processing stability.

[0005] To achieve the above-mentioned process effects, the technical solution of the present invention is as follows: a high-temperature resistant packaging film for ovens, which is a co-extruded film, comprising, from the outside to the inside, a high-temperature resistant outer layer, a toughening core layer and a high-temperature resistant heat-sealing layer stacked sequentially, wherein the high-temperature resistant outer layer comprises at least two high-temperature resistant unit layers and the toughening core layer comprises at least two toughening unit layers. The raw materials for both the high-temperature resistant unit layer and the toughening unit layer include homopolymer nylon, toughening nylon, elastomer, and high-temperature resistant masterbatch; The raw materials of the high-temperature heat-sealing layer include homopolymer nylon, heat-sealing nylon and high-temperature masterbatch; The high-temperature resistant masterbatch includes nylon 6, heat resistant agent and antioxidant; The heat-resistant agent is N-(4-fluorophenyl)maleimide-styrene copolymer and N-(4-carboxyphenyl)maleimide-trimethyleneisocyanurate copolymer.

[0006] The preferred technical solution is that, by weight, the raw materials of the high-temperature resistant unit layer include 60-70 parts of homopolymer nylon, 30-40 parts of toughened nylon, 4.5-5.5 parts of elastomer, and 1.8-2.5 parts of high-temperature resistant masterbatch; The raw materials for the toughening unit layer include 60-65 parts of homopolymer nylon, 27-33 parts of toughening nylon, 4.5-5.5 parts of elastomer, and 1.8-2.5 parts of high-temperature resistant masterbatch; The raw materials for the high-temperature heat-sealing layer include 27-33 parts of homopolymer nylon, 67-73 parts of heat-sealing nylon, and 1.8-2.4 parts of high-temperature masterbatch.

[0007] A preferred technical solution is that the high-temperature resistant masterbatch includes a first high-temperature resistant masterbatch and a second high-temperature resistant masterbatch. The first high-temperature resistant masterbatch includes nylon 6 and N-(4-carboxyphenyl)maleimide-trylyl isocyanurate copolymer, and the second high-temperature resistant masterbatch includes nylon 6, N-(4-fluorophenyl)maleimide-styrene copolymer and antioxidant.

[0008] A preferred technical solution is that the mass ratio of the first high-temperature resistant masterbatch to the second high-temperature resistant masterbatch is (0.5~1):1.

[0009] The preferred technical solution is that the mass ratio of nylon 6 and N-(4-carboxyphenyl)maleimide-tracelyl isocyanurate copolymer in the first high-temperature resistant masterbatch is 100:(8~12); and the mass ratio of nylon 6, N-(4-fluorophenyl)maleimide-styrene copolymer and antioxidant in the second high-temperature resistant masterbatch is 100:(14~18):(0.5~2).

[0010] A preferred technical solution is that the antioxidant is a combination of hindered phenolic antioxidants and phosphite antioxidants.

[0011] The preferred technical solution is that the first high-temperature resistant masterbatch is obtained by blending, extrusion granulation and irradiation crosslinking, and the second high-temperature resistant masterbatch is obtained by blending and extrusion granulation.

[0012] The preferred technical solution is that the homopolymer nylon is BASF B40LN, and / or the toughened nylon is 842A NT0733, and / or the heat-sealing nylon is BASF C40L.

[0013] The second objective of this invention is to overcome the deficiencies in the prior art and provide a method for preparing a high-temperature resistant packaging film for ovens. Based on the above-mentioned high-temperature resistant packaging film for ovens, the high-temperature resistant heat-sealing layer includes a heat-sealing transition layer and a heat-sealing surface layer. The heat-sealing transition layer is close to the toughening unit layer. The raw materials of each layer are mixed and then co-extruded in multiple layers. The extrusion temperature of each high-temperature resistant unit layer is 250~260℃, the extrusion temperature of each toughening unit layer is 250~260℃, the extrusion temperature of the heat-sealing transition layer is 250~260℃, and the extrusion temperature of the heat-sealing surface layer is 245~255℃.

[0014] A preferred technical solution is that the thickness of the high-temperature resistant outer layer accounts for 20% to 24% of the total thickness of the packaging film, the thickness of the toughening core layer accounts for 40% to 46% of the total thickness of the packaging film, the thickness of the heat-sealing transition layer accounts for 6% to 8% of the total thickness of the packaging film, the thickness of the heat-sealing surface layer accounts for 25% to 30% of the total thickness of the packaging film, and the total thickness of the packaging film is 45 to 60 μm.

[0015] The advantages and beneficial effects of this invention are as follows: The overall high-temperature resistance of the packaging film is optimized by compounding homopolymer nylon with high-temperature resistant masterbatch in each layer. The content of homopolymer nylon in each layer decreases sequentially from the outside to the inside, forming a packaging film with temperature difference. The outer layer is a high-temperature shield layer that absorbs a large amount of heat. The material has low thermal conductivity, and the cooking process may be much shorter than the time required for heat to fully penetrate and reach its melting point, thus effectively preventing the heat seal layer from being scalded. The heat resistant agent compounded by N-(4-fluorophenyl)maleimide-styrene copolymer and N-(4-carboxyphenyl)maleimide-tracelyl isocyanurate copolymer optimizes the temperature resistance of the packaging film, improves compatibility, and enhances processability and processing stability. Detailed Implementation

[0016] The specific embodiments of the present invention will be further described below with reference to examples. These examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0017] heat resistant agent The heat resistant agent is a combination of N-(4-fluorophenyl)maleimide-styrene copolymer and N-(4-carboxyphenyl)maleimide-tracelyl isocyanurate copolymer.

[0018] Preparation of N-(4-fluorophenyl)maleimide-styrene copolymer: First, the synthesis of N-(fluorophenyl)maleimide was carried out by dissolving maleic anhydride in N,N-dimethylformamide and fluoroaniline in N,N-dimethylformamide. The reaction mixture was then added dropwise to the reaction mixture. The molar ratio of maleic anhydride to fluoroaniline was 1:1.1. The reaction temperature was controlled at 25~30℃ and the reaction was maintained for 3 hours. Next, anhydrous sodium acetate catalyst, hydroquinone polymerization inhibitor, and acetic anhydride dehydrating agent were added to the reaction mixture. The temperature was then raised to 50~55℃ and the reaction was maintained for 3 hours. The amount of anhydrous sodium acetate added was 10% of the total molar mass of maleic anhydride and aniline, the amount of hydroquinone polymerization inhibitor added was 6% of the total molar mass of maleic anhydride and aniline, and the amount of acetic anhydride added was 45% of the total molar mass of maleic anhydride and aniline. Finally, the mixture was filtered, washed, and dried. Furthermore, N-(fluorophenyl)maleimide and styrene are copolymerized via free radicals. The N-(fluorophenyl)maleimide and styrene are mixed and added to cyclohexanone solvent. Benzoyl peroxide (BPO) initiator is added dropwise, and the temperature is gradually raised to 98°C. The reaction time is maintained at this temperature for 3 hours. In this case, N-(fluorophenyl)maleimide and styrene are mixed in equimolar amounts for copolymerization, and the amount of initiator added is 2% of the total mass of N-(fluorophenyl)maleimide and styrene.

[0019] Preparation of N-(4-carboxyphenyl)maleimide-tracelyl isocyanurate copolymer: First, the synthesis of N-(carboxyphenyl)maleimide was carried out by dissolving maleic anhydride in N,N-dimethylformamide and p-aminobenzoic acid in N,N-dimethylformamide. The reaction mixture was then added dropwise to the initial reaction mixture. The molar ratio of maleic anhydride to p-aminobenzoic acid was 1:1. The reaction temperature was controlled at 25~30℃, and the reaction was maintained at this temperature. 2h; then add the catalyst anhydrous sodium acetate, the polymerization inhibitor hydroquinone, and the dehydrating agent acetic anhydride to the reaction solution, then raise the temperature to 50~55℃ and keep the reaction at that temperature for 3h. The amount of anhydrous sodium acetate added is 10% of the total molar mass of maleic anhydride and aniline, the amount of polymerization inhibitor hydroquinone added is 6% of the total molar mass of maleic anhydride and aniline, and the amount of acetic anhydride added is 45% of the total molar mass of maleic anhydride and aniline; then filter, wash and dry. Furthermore, N-(carboxyphenyl)maleimide and triallyl isocyanurate are copolymerized via free radicals. The mixture of N-(carboxyphenyl)maleimide and triallyl isocyanurate is added to cyclohexanone solvent, and benzoyl peroxide (BPO) is added dropwise. The temperature is gradually raised to 105°C, and the reaction is maintained at this temperature for 3 hours. In this case, N-(carboxyphenyl)maleimide and triallyl isocyanurate are mixed in equimolar amounts for copolymerization, and the amount of initiator added is 2% of the total mass of N-(carboxyphenyl)maleimide and triallyl isocyanurate.

[0020] High temperature resistant masterbatch The high-temperature resistant masterbatch includes a first high-temperature resistant masterbatch and a second high-temperature resistant masterbatch.

[0021] The first high-temperature resistant masterbatch is made from nylon 6 and N-(4-carboxyphenyl)maleimide-tracelyl isocyanurate copolymer, which are obtained through blending, extrusion granulation, and irradiation crosslinking. The extrusion granulation temperatures are sequentially set to 190℃, 210℃, 225℃, 230℃, 235℃, 240℃, and 245℃, with a die temperature of 255℃. The masterbatch is irradiated with 90 kGy of gamma rays.

[0022] The second high-temperature resistant masterbatch consists of nylon 6, N-(4-fluorophenyl)maleimide-styrene copolymer, and antioxidants, which are obtained through blending and extrusion granulation. The extrusion granulation temperatures are sequentially set to 190℃, 210℃, 225℃, 230℃, 235℃, 240℃, and 245℃, with a die temperature of 255℃. The core function of the antioxidant is to interrupt the aging chain reaction of the material at different stages, collectively providing the material with excellent processing thermal stability and long-term resistance to thermo-oxidative aging.

[0023] The high-temperature resistant masterbatch uses nylon 6 as the base material, which has good compatibility with homopolymer nylon. This improves the compatibility between the high-temperature resistant masterbatch and the raw materials of the high-temperature resistant outer layer, toughening core layer, and high-temperature resistant heat-sealing layer, thereby optimizing the mechanical properties and high-temperature resistance of each layer. Furthermore, the nylon 6 is either model F136-E2 from Royal DSM Group in the Netherlands or model J40TFE from Taiwan, China.

[0024] In the preparation of masterbatch by blending N-(4-carboxyphenyl)maleimide-tracelyl isocyanurate copolymer with nylon 6, after irradiation, the carbon-carbon double bonds of the reactive functional group crosslink with the nylon molecular chains of the substrate to form a network structure, forming good interfacial strength, which hinders the movement and rotation of polymer molecular chains, and promotes the formation of a network structure from the rigid structure in N-(4-carboxyphenyl)maleimide-tracelyl isocyanurate copolymer. When mixed with the raw materials of high-temperature resistant outer layer, toughening core layer and high-temperature resistant heat-sealing layer, it further enhances the heat resistance of the high-temperature resistant outer layer, toughening core layer and high-temperature resistant heat-sealing layer in the packaging film.

[0025] In the blending of N-(4-fluorophenyl)maleimide-styrene copolymer with nylon 6 and antioxidants, the N-(4-fluorophenyl)maleimide-styrene copolymer is dispersed in the substrate as microspheres with a particle size of 300~600nm. When mixed with the raw materials of high-temperature resistant outer layer, toughening core layer and high-temperature resistant heat-sealing layer, it restricts the freedom of nylon. In particular, the fluorine group is an electron-absorbing group, which forms hydrogen bonds with the electron-donating groups of amide, amino or carboxyl groups in nylon. Complexation occurs at the interface between the mixed materials, inducing nylon to form α crystals. The α crystals exhibit rigidity, thereby enhancing the heat resistance of the high-temperature resistant outer layer, toughening core layer and high-temperature resistant heat-sealing layer in the packaging film.

[0026] Heat resistant agents containing maleic anhydride can improve their compatibility with nylon. The aforementioned heat resistant agents all contain rigid and polar structures. The polar structure interacts with the polar structures in the substrate and the raw materials of each layer, while the steric hindrance effect of the rigid structure hinders the movement of molecular chains, thereby improving the overall heat resistance of each layer and the packaging film.

[0027] Composition of each layer of high-temperature resistant packaging film By weight, the raw materials for the high-temperature resistant unit layer include 60-70 parts of homopolymer nylon, 30-40 parts of toughened nylon, 4.5-5.5 parts of elastomer, and 1.8-2.5 parts of high-temperature resistant masterbatch; The raw materials for the toughening unit layer include 60-65 parts of homopolymer nylon, 27-33 parts of toughening nylon, 4.5-5.5 parts of elastomer, and 1.8-2.5 parts of high-temperature resistant masterbatch; The raw materials for the high-temperature heat-sealing layer include 27-33 parts of homopolymer nylon, 67-73 parts of heat-sealing nylon, and 1.8-2.4 parts of high-temperature masterbatch.

[0028] The heat-sealing nylon content in the high-temperature heat-sealing layer needs to ensure a heat-sealing strength of 8-12N. It must also possess good toughness to prevent puncture in food contact, while maintaining high-temperature resistance.

[0029] Each layer of raw materials is optimized for overall high-temperature resistance by combining homopolymer nylon with high-temperature resistant masterbatch. The content of homopolymer nylon in the high-temperature resistant outer layer, toughening core layer, and high-temperature resistant heat-sealing layer, which are stacked sequentially from the outside to the inside, is reduced in order to obtain the outer layer with the highest thermal stability and the toughening core layer with the second highest thermal stability. This forms a packaging film with temperature difference. The outer layer is like a high-temperature shield layer, which absorbs a large amount of heat first. The material itself does not conduct heat particularly quickly, and it takes time for heat to be transferred from the outer layer to the heat-sealing layer. The entire cooking process may be much shorter than the time required for heat to fully penetrate and bring the heat-sealing layer to its melting point, thus effectively preventing the heat-sealing layer from being scalded.

[0030] Example 1

[0031] The high-temperature resistant packaging film for ovens is a seven-layer co-extruded film, consisting of a high-temperature resistant outer layer, a toughening core layer, and a high-temperature resistant heat-sealing layer stacked sequentially from the outside to the inside. The high-temperature resistant outer layer includes two high-temperature resistant unit layers, the toughening core layer includes three toughening unit layers, and the high-temperature resistant heat-sealing layer includes a heat-sealing transition layer and a heat-sealing surface layer, with the heat-sealing transition layer located close to the toughening unit layers.

[0032] By weight, the raw materials for the high-temperature resistant unit layer include 68 parts of homopolymer nylon (BASF B40LN, Germany), 30 parts of toughened nylon (842A NT0733), 5 parts of elastomer (Ascend, USA), and 2 parts of high-temperature resistant masterbatch; the raw materials for the toughening unit layer include 63 parts of homopolymer nylon (BASF B40LN, Germany), 30 parts of toughened nylon (842A NT0733), 5 parts of elastomer, and 2 parts of high-temperature resistant masterbatch; the raw materials for the high-temperature resistant heat-sealing layer include 30 parts of homopolymer nylon (BASF B40LN, Germany), 70 parts of heat-sealing nylon (BASF C40L, Germany), and 2 parts of high-temperature resistant masterbatch.

[0033] The high-temperature resistant masterbatch includes nylon 6, a heat-resistant agent, and an antioxidant. The high-temperature resistant masterbatch comprises a first high-temperature resistant masterbatch and a second high-temperature resistant masterbatch with a mass ratio of 0.65:1. The first high-temperature resistant masterbatch consists of nylon 6 and N-(4-carboxyphenyl)maleimide-tracelyl isocyanurate copolymer, mixed sequentially at a mass ratio of 100:10. The second high-temperature resistant masterbatch consists of nylon 6, N-(4-fluorophenyl)maleimide-styrene copolymer, and an antioxidant, mixed sequentially at a mass ratio of 100:16:1.2. The antioxidant is a combination of hindered phenolic antioxidants and phosphite antioxidants; the hindered phenolic antioxidant is 1098 antioxidant, and the phosphite antioxidant is 168 antioxidant, with a mass ratio of 1:0.5.

[0034] The above-mentioned method for preparing high-temperature resistant packaging film for ovens includes five temperature ranges for each high-temperature resistant unit layer, set sequentially as 210℃, 255℃, 255℃, 255℃, and 255℃; five temperature ranges for each toughening unit layer, set sequentially as 210℃, 255℃, 255℃, 255℃, and 255℃; five temperature ranges for the heat-sealing transition layer, set sequentially as 210℃, 255℃, 255℃, 255℃, and 255℃; and five temperature ranges for the heat-sealing surface layer, set sequentially as 210℃, 250℃, 250℃, 250℃, and 250℃.

[0035] The total thickness of the seven-layer co-extruded packaging film is 50μm. Among them, the thickness of the high-temperature resistant outer layer is 11μm, the thickness of each high-temperature resistant unit layer is 5.5μm, the thickness of the toughening core layer is 22μm, the thickness of the toughening unit layer near the high-temperature resistant outer layer is 11μm, the thickness of the other two toughening unit layers is 5.5μm, the thickness of the heat-sealing transition layer is 3.5μm, and the thickness of the heat-sealing surface layer is 13.5μm.

[0036] Example 2

[0037] Example 2 is based on Example 1, except that the high-temperature resistant packaging film for ovens is a five-layer co-extruded film, which includes, from the outside to the inside, a high-temperature resistant outer layer, a toughening core layer, and a high-temperature resistant heat-sealing layer stacked sequentially. The high-temperature resistant outer layer includes two high-temperature resistant unit layers, the toughening core layer includes two toughening unit layers, and the high-temperature resistant heat-sealing layer only includes a heat-sealing surface layer. The composition of each layer remains unchanged, and the total thickness of the five-layer co-extruded packaging film is still 50 μm.

[0038] Example 3

[0039] Example 3 is based on Example 1, except that, by mass parts, the raw materials of the high-temperature resistant unit layer include 63 parts of homopolymer nylon (BASF B40LN, Germany), 30 parts of toughened nylon (842A NT0733), 5 parts of elastomer (Ascend, USA), and 2 parts of high-temperature resistant masterbatch; the raw materials of the toughening unit layer include 63 parts of homopolymer nylon (BASF B40LN, Germany), 30 parts of toughened nylon (842ANT0733), 5 parts of elastomer, and 2 parts of high-temperature resistant masterbatch; the raw materials of the high-temperature resistant heat-sealing layer include 30 parts of homopolymer nylon (BASF B40LN, Germany), 70 parts of heat-sealing nylon (BASF C40L, Germany), and 2 parts of high-temperature resistant masterbatch.

[0040] Example 4

[0041] Example 4 is based on Example 1, with the following difference. By mass parts, the raw materials for the high-temperature resistant unit layer include 48 parts of homopolymer nylon (BASF B40LN, Germany), 45 parts of toughened nylon (842A NT0733), 5 parts of elastomer (Ascend, USA), and 2 parts of high-temperature resistant masterbatch; the raw materials for the toughening unit layer include 63 parts of homopolymer nylon (BASF B40LN, Germany), 30 parts of toughened nylon (842ANT0733), 5 parts of elastomer, and 2 parts of high-temperature resistant masterbatch; the raw materials for the high-temperature resistant heat-sealing layer include 30 parts of homopolymer nylon (BASF B40LN, Germany), 70 parts of heat-sealing nylon (BASF C40L, Germany), and 2 parts of high-temperature resistant masterbatch.

[0042] Example 5

[0043] Example 5 is based on Example 1, except that the high-temperature resistant masterbatch includes a first high-temperature resistant masterbatch and a second high-temperature resistant masterbatch with a mass ratio of 1:1. Only the ratio is changed, and the other components remain the same.

[0044] Example 6

[0045] Example 6 is based on Example 1, except that the high-temperature resistant masterbatch includes a first high-temperature resistant masterbatch and a second high-temperature resistant masterbatch with a mass ratio of 1.5:1. Only the ratio is changed, and the other components remain the same.

[0046] Comparative Example 1 Comparative Example 1 is based on Example 1, except that the heat resistant agent is only N-(4-fluorophenyl)maleimide-styrene copolymer, while other components and contents remain unchanged.

[0047] Comparative Example 2 Comparative Example 2 is based on Example 1, except that the heat resistant agent is only N-(4-carboxyphenyl)maleimide-tracelyl isocyanurate copolymer, while other components and contents remain unchanged.

[0048] Performance testing of protective film samples prepared in the examples and comparative examples: (1) Tensile strength and fracture growth rate: determined according to standard GB / T1040.3; (2) Heat seal strength: determined according to standard QB / T2358; (3) Temperature resistance: Place the product in ovens at 150℃, 180℃ and 190℃ and heat for 20 minutes to see if it deforms; (4) Oxygen permeability: determined according to standard GB / T1038-2000; The performance test results of the examples and comparative examples are as follows:

[0049] The heat-sealing strength of the packaging films in the examples and comparative examples is between 8 and 12 N, mainly determined by the type and content of the heat-sealing nylon.

[0050] Compared to Example 1, Example 2 shows that the seven-layer co-agent raw materials are more evenly dispersed and the packaging film has better toughness, resulting in superior mechanical properties. The five-layer co-agent has the second least stable layer structure, leading to thermal deformation at 190°C.

[0051] Compared to Example 1, Example 3 has a lower content of homopolymer nylon and a higher relative content of toughened nylon in the raw materials of the high-temperature resistant unit layer, resulting in better toughness of the packaging film. However, the duration of high-temperature resistance at 190°C is not good, and slight deformation occurs after more than 20 minutes.

[0052] Compared to Example 1, Example 4 shows that the content of homopolymer nylon in the raw material of the high-temperature resistant unit layer is too low, which leads to a decrease in the heat resistance of the high-temperature resistant outer layer and makes it prone to deformation during high-temperature heating.

[0053] Compared to Example 1, Example 6 shows that with the same amount of high-temperature resistant masterbatch added, the content of the first high-temperature resistant masterbatch is increased, which increases the processing difficulty and easily leads to uneven dispersion of the high-temperature resistant masterbatch. This not only reduces the toughness of the packaging film but also has a negative impact on the temperature resistance.

[0054] Compared to Example 1, Comparative Examples 1 and 2 showed the best effect in optimizing the temperature resistance of the packaging film by using a heat-resistant agent composed of N-(4-fluorophenyl)maleimide-styrene copolymer and N-(4-carboxyphenyl)maleimide-tracelyl isocyanurate copolymer.

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-temperature resistant packaging film for ovens, which is a co-extruded film, characterized in that, From the outside to the inside, it includes a high-temperature resistant outer layer, a toughened core layer, and a high-temperature resistant heat-sealing layer stacked sequentially. The high-temperature resistant outer layer includes at least two high-temperature resistant unit layers, and the toughened core layer includes at least two toughening unit layers. The raw materials for both the high-temperature resistant unit layer and the toughening unit layer include homopolymer nylon, toughening nylon, elastomer, and high-temperature resistant masterbatch; The raw materials of the high-temperature heat-sealing layer include homopolymer nylon, heat-sealing nylon and high-temperature masterbatch; The high-temperature resistant masterbatch includes nylon 6, heat resistant agent and antioxidant; The heat-resistant agent is N-(4-fluorophenyl)maleimide-styrene copolymer and N-(4-carboxyphenyl)maleimide-trimethyleneisocyanurate copolymer.

2. The high-temperature resistant packaging film for ovens according to claim 1, characterized in that, By weight, the raw materials of the high-temperature resistant unit layer include 60-70 parts of homopolymer nylon, 30-40 parts of toughened nylon, 4.5-5.5 parts of elastomer, and 1.8-2.5 parts of high-temperature resistant masterbatch; The raw materials for the toughening unit layer include 60-65 parts of homopolymer nylon, 27-33 parts of toughening nylon, 4.5-5.5 parts of elastomer, and 1.8-2.5 parts of high-temperature resistant masterbatch; The raw materials for the high-temperature heat-sealing layer include 27-33 parts of homopolymer nylon, 67-73 parts of heat-sealing nylon, and 1.8-2.4 parts of high-temperature masterbatch.

3. The high-temperature resistant packaging film for ovens according to claim 1 or 2, characterized in that, The high-temperature resistant masterbatch includes a first high-temperature resistant masterbatch and a second high-temperature resistant masterbatch. The first high-temperature resistant masterbatch includes nylon 6 and N-(4-carboxyphenyl)maleimide-trimethylene isocyanurate copolymer, and the second high-temperature resistant masterbatch includes nylon 6, N-(4-fluorophenyl)maleimide-styrene copolymer and antioxidant.

4. The high-temperature resistant packaging film for ovens according to claim 3, characterized in that, The mass ratio of the first high-temperature resistant masterbatch to the second high-temperature resistant masterbatch is (0.5~1):

1.

5. The high-temperature resistant packaging film for ovens according to claim 3, characterized in that, The mass ratio of nylon 6 and N-(4-carboxyphenyl)maleimide-tallyl isocyanurate copolymer in the first high-temperature resistant masterbatch is 100:(8~12); the mass ratio of nylon 6, N-(4-fluorophenyl)maleimide-styrene copolymer and antioxidant in the second high-temperature resistant masterbatch is 100:(14~18):(0.5~2).

6. The high-temperature resistant packaging film for ovens according to claim 1 or 5, characterized in that, The antioxidant is a combination of hindered phenolic antioxidants and phosphite antioxidants.

7. The high-temperature resistant packaging film for ovens according to claim 3, characterized in that, The first high-temperature resistant masterbatch was obtained by blending, extrusion granulation and irradiation crosslinking, and the second high-temperature resistant masterbatch was obtained by blending and extrusion granulation.

8. The high-temperature resistant packaging film for ovens according to claim 1 or 2, characterized in that, The homopolymer nylon is of model number B40LN from BASF, Germany, and / or the toughened nylon is of model number 842A NT0733, and / or the heat-sealing nylon is of model number C40L from BASF, Germany.

9. A method for preparing a high-temperature resistant packaging film for ovens, characterized in that, Based on the high-temperature resistant packaging film for ovens according to any one of claims 1 to 8, the high-temperature resistant heat-sealing layer includes a heat-sealing transition layer and a heat-sealing surface layer. The heat-sealing transition layer is close to the toughening unit layer. The raw materials of each layer are mixed and co-extruded in multiple layers. The extrusion temperature of each layer of the high-temperature resistant unit layer is 250~260℃, the extrusion temperature of each layer of the toughening unit layer is 250~260℃, the extrusion temperature of the heat-sealing transition layer is 250~260℃, and the extrusion temperature of the heat-sealing surface layer is 245~255℃.

10. The method for preparing a high-temperature resistant packaging film for ovens according to claim 9, characterized in that, The thickness of the high-temperature resistant outer layer accounts for 20% to 24% of the total thickness of the packaging film, the thickness of the toughening core layer accounts for 40% to 46% of the total thickness of the packaging film, the thickness of the heat-sealing transition layer accounts for 6% to 8% of the total thickness of the packaging film, the thickness of the heat-sealing surface layer accounts for 25% to 30% of the total thickness of the packaging film, and the total thickness of the packaging film is 45 to 60 μm.

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