High-barrier high-temperature-resistant cooking packaging film based on single PP recyclable material

Abstract

The invention relates to the technical field of high-temperature-cooking-resistant packaging materials, and discloses a high-barrier high-temperature-cooking-resistant packaging film based on a single-PP recyclable material. A preparation method of the packaging film comprises the following steps: firstly compounding alkenyl phenyl double-splint structure cage type polysilsesquioxane with graphene oxide through a pi-pi stacking effect and a hydrogen-bond interaction; loading the mixture onto polypropylene resin through a free radical coupling reaction and a molecular chain intercalation manner; and finally, extruding by utilizing a double-screw extruder to obtain the high-resistance polypropylene-based composite material with high temperature resistance and puncture resistance. The high-barrier high-temperature-resistant cooking packaging film based on the single PP recyclable material is prepared by taking a high-temperature-resistant and puncture-resistant high-barrier polypropylene-based composite material as a middle-layer raw material of a five-layer co-extrusion film made of a single PP material and adopting a five-layer co-extrusion blow molding film forming process, the film product is free of abnormal phenomena such as deformation and stripping after being cooked for 30 minutes at 140 DEG C, and the packaging film has the advantages that the packaging film is high in barrier property and high in high-temperature-resistant cooking property; and excellent barrier property and puncture resistance are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of high temperature cooking resistant packaging materials, and in particular to a high barrier high temperature cooking resistant packaging film based on a single PP recyclable material. Background Art

[0002] High temperature cooking resistant packaging is commonly used for meat, bean products and other food packaging. It is generally vacuum packed and sterilized at high temperature (100-135℃) and can be stored at room temperature. Food in cooking resistant packaging is easy to carry and ready to eat after opening the bag. It is hygienic and convenient, and can well maintain the flavor of the food, which is deeply loved by consumers.

[0003] High-temperature resistant retort packaging is usually made of a composite of multiple base materials. Common materials include PA, PET, AL and PP. Common structures include two-layer composite films (such as BOPA / PP, PET / PP), three-layer composite films (such as PA / AL / PP, PET / PA / PP) and four-layer composite films (such as PET / PA / AL / PP). However, multi-material composite packaging is difficult to classify and recycle after it is discarded at the end of its life cycle, which can easily cause waste of resources and environmental pollution.

[0004] When recycling, packaging films made of PP alone do not need to be classified and can be recycled repeatedly. However, their puncture resistance is far inferior to that of PA and they are easily damaged when pierced by sharp objects. As high-temperature cooking packaging films, they are prone to quality problems such as bag breakage and air leakage, which affect the vacuum degree of product packaging and cause product deterioration. In addition, the barrier properties of packaging films made of PP alone usually cannot meet the requirements for the actual use of high-temperature cooking packaging films, which limits their application value. Therefore, PP usually needs to be modified.

[0005] The modification methods of polypropylene can be divided into chemical modification and physical modification. Chemical modification mainly changes the molecular chain structure of polypropylene to improve the material properties. Chemical modification mainly includes copolymerization, grafting, cross-linking, etc. Physical modification is to change the higher-order structure of polypropylene materials to achieve the purpose of improving material properties. Physical modification mainly includes blending, filling, etc.

[0006] As a derivative of graphene, graphene oxide has a two-dimensional flaky structure similar to graphene. Adding it as a filler into a polymer matrix can extend the path for water vapor and small gas molecules to pass through the composite material, thereby improving the barrier properties of the composite material. Summary of the invention

[0007] The present invention has developed a high-barrier, high-temperature-resistant cooking packaging film based on a single PP recyclable material. After being cooked at 140°C for 30 minutes, the film product has no abnormal phenomena such as deformation, interlayer peeling, and peeling at the heat-sealed part, and has excellent barrier properties and puncture resistance.

[0008] A high-barrier, high-temperature cooking-resistant packaging film based on a single PP recyclable material, the product structure of the film comprising the following layers arranged in sequence: PP layer / PP-g-MAH layer / functional layer / PP-g-MAH layer / MPP layer; PP layer: the raw material formula is 100wt% polypropylene resin, the dosage is 20-35 parts by weight; PP-g-MAH layer: the raw material formula is 100wt% maleic anhydride grafted polypropylene resin, the dosage is 3-10 parts by weight; MPP layer: the raw material formula is 100wt% metallocene polypropylene resin, the dosage is 20-35 parts by weight; Functional layer: The raw material formula is 100wt% of a high-barrier polypropylene-based composite material that is resistant to high temperatures and punctures, and the dosage is 20-35 parts by weight; The high-barrier polypropylene-based composite material that is resistant to high temperature and puncture is obtained by first compounding olefinic phenyl double-sandwich structure cage-type polysilsesquioxane with graphene oxide through π-π stacking and hydrogen bonding, and then loading it onto polypropylene resin through free radical coupling reaction and molecular chain intercalation.

[0009] Preferably, the formula of the high-barrier polypropylene-based composite material that is resistant to high temperature and puncture is 85-90wt% polypropylene resin, 1-8wt% olefinated phenyl double-sandwich structure cage-type polysilsesquioxane, 0.5-2wt% peroxide initiator and 3-10wt% graphene oxide.

[0010] Preferably, the preparation method of the alkenylated phenyl double-sandwich structure cage-type polysilsesquioxane is: Phenyltrimethoxysilane is used as a raw material, and a hydrolysis-condensation method is adopted to catalyze the hydrolysis and polycondensation reaction of phenyltrimethoxysilane with sodium hydroxide to generate an incompletely condensed double-sandwich structure cage-type polysilsesquioxane sodium salt; The isocyanate-terminated phenyl double-sandwich cage-type polysilsesquioxane was synthesized by the vertex-capping method using incompletely condensed double-sandwich cage-type polysilsesquioxane sodium salt as raw material and 3-isocyanatopropylmethyldichlorosilane as capping agent under the catalysis of triethylamine. By utilizing the nucleophilic addition reaction mechanism, under the catalytic action of an organic base catalyst, the isocyanate group of the terminal isocyanate phenyl double-sandwich structure cage-type polysilsesquioxane undergoes a decarboxylation condensation reaction with the carboxyl functional group of oleic acid to generate an olefinic phenyl double-sandwich structure cage-type polysilsesquioxane.

[0011] Preferably, the organic base catalyst is one of triethylamine, triethylenediamine, pyridine and 4-dimethylaminopyridine.

[0012] Preferably, the preparation method of the high temperature resistant and puncture resistant high barrier polypropylene-based composite material is: Step 1: Based on π-π stacking and hydrogen bonding, alkenyl phenyl double-sandwich structure cage-type polysilsesquioxane is compounded with graphene oxide to obtain an alkenyl phenyl double-sandwich structure cage-type polysilsesquioxane / graphene composite material; Step 2: Based on the free radical coupling reaction mechanism under the action of peroxide initiator and molecular chain intercalation technology, the polypropylene resin is modified using an olefinic phenyl double-sandwich structure cage-type polysilsesquioxane / graphene composite material, and extruded and granulated using a twin-screw extruder to obtain a high-barrier polypropylene-based composite material that is resistant to high temperature and puncture.

[0013] Preferably, the graphene oxide has a sheet diameter of 3-10 μm and a thickness of 8-15 nm.

[0014] Preferably, the peroxide initiator is one of dicumyl peroxide, tert-butyl hydroperoxide, dibenzoyl peroxide, and tert-butyl perbenzoate.

[0015] Preferably, the thickness of the high-barrier high-temperature cooking-resistant packaging film is 50-150 μm.

[0016] Preferably, the high-barrier high-temperature cooking-resistant packaging film based on a single PP recyclable material is used under the condition of a temperature ≤ 140°C.

[0017] Beneficial effects: The present invention designs and synthesizes an olefinic phenyl double-sandwich structure cage-type polysilsesquioxane, and prepares a high-barrier polypropylene-based composite material that is resistant to high temperatures and punctures; The high-barrier polypropylene-based composite material with high temperature resistance and puncture resistance was used as the middle layer raw material of the five-layer co-extruded film with a single PP material. A high-barrier high-temperature cooking-resistant packaging film based on a single PP recyclable material was prepared by a five-layer co-extrusion blow molding process. After being cooked at 140°C for 30 minutes, the film had no abnormal phenomena such as deformation, interlayer peeling and peeling at the heat-sealed part, showing excellent high-temperature cooking resistance. The high-barrier high-temperature cooking-resistant packaging film prepared by the present invention has achieved a beneficial technical effect of significantly improving puncture resistance and barrier properties compared to conventional polypropylene films prepared using conventional polypropylene resins; The high-barrier high-temperature cooking-resistant packaging film prepared by the invention has excellent comprehensive performance, and its sanitary performance meets the requirements of national standards, and can be used in high-temperature cooking-resistant food packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the chemical structural formula of terminal isocyanate phenyl double-plywood structure cage-type polysilsesquioxane; Figure 2 It is the chemical structural formula of alkenyl phenyl double-sandwich structure cage-type polysilsesquioxane; Figure 3 These are the performance test results of high-barrier and high-temperature cooking-resistant packaging films based on a single PP recyclable material. DETAILED DESCRIPTION

[0019] The present invention first uses phenyltrimethoxysilane as a raw material to prepare an incompletely condensed double-ply structure cage-type polysilsesquioxane sodium salt through a hydrolysis-condensation method, then uses 3-isocyanatopropylmethyldichlorosilane as a capping agent to prepare an isocyanate-terminated phenyl double-ply structure cage-type polysilsesquioxane through a vertex-capping method, and utilizes an isocyanate-carboxyl nucleophilic addition reaction to graft oleic acid (commonly used as a plasticizer and a surface modifier for improving water and oil barrier properties in the field of packaging film manufacturing) onto the double-ply structure cage-type polysilsesquioxane to prepare an olefinated phenyl double-ply structure cage-type polysilsesquioxane; After the alkenylated phenyl double-sandwich structure cage-type polysilsesquioxane is compounded with graphene oxide through π-π stacking and hydrogen bonding, the modification effect of polypropylene resin is achieved through free radical coupling reaction and molecular chain intercalation, and finally a high-barrier polypropylene-based composite material that is resistant to high temperature and puncture is obtained. Embodiment 1:

[0020] A high-barrier, high-temperature-resistant cooking packaging film I based on a single PP recyclable material, the product structure of which is: The first layer: a PP layer made of 100wt% polypropylene resin (brand name HJ4012), with an amount of 30 parts by weight; The second layer: a PP-g-MAH layer prepared from 100wt% maleic anhydride grafted polypropylene resin (brand name QB510), with an amount of 5 parts by weight; The third layer: a functional layer made of 100wt% high-temperature-resistant and puncture-resistant high-barrier polypropylene-based composite material, with an amount of 30 parts by weight; The fourth layer: a PP-g-MAH layer prepared from 100 wt% maleic anhydride grafted polypropylene resin, with an amount of 5 parts by weight; The fifth layer: an MPP layer prepared from 100 wt% metallocene polypropylene resin (brand name MR30MC2), with an amount of 30 parts by weight; Among them, the formula of the high-barrier polypropylene-based composite material that is resistant to high temperature and puncture is: 90wt% polypropylene resin, 3wt% olefinated phenyl double-sandwich structure cage-type polysilsesquioxane, 1wt% peroxide initiator and 6wt% graphene oxide (sheet diameter 3-10μm, thickness 8-15nm); The preparation process of alkenyl phenyl double-sandwich structure cage-type polysilsesquioxane is as follows: The first step: using phenyltrimethoxysilane as a raw material, adopting a hydrolysis-condensation method, catalyzing phenyltrimethoxysilane with sodium hydroxide to undergo a hydrolysis-condensation reaction, thereby generating an incompletely condensed double-sandwich structure cage-type polysilsesquioxane sodium salt, the chemical structure of which is: ; Step 2: Using the incompletely condensed double-sandwich structure cage-type polysilsesquioxane sodium salt as raw material and 3-isocyanatopropylmethyldichlorosilane as a capping agent, a terminal isocyanate phenyl double-sandwich structure cage-type polysilsesquioxane is synthesized by the vertex-capping method under the catalysis of triethylamine. The chemical structure is as follows: Figure 1 As shown; Step 3: Using the nucleophilic addition reaction mechanism, under the catalytic action of an organic base catalyst, the isocyanate group of the terminal isocyanate phenyl double-sandwich structure cage-type polysilsesquioxane undergoes a decarboxylation condensation reaction with the carboxyl functional group of oleic acid to generate an olefinic phenyl double-sandwich structure cage-type polysilsesquioxane, the chemical structure of which is as follows: Figure 2 As shown; Among them, the organic base catalyst is selected from one of triethylamine, triethylenediamine, pyridine, and 4-dimethylaminopyridine; 4-dimethylaminopyridine is preferably used in this embodiment; The specific experimental steps for preparing alkenyl phenyl double-sandwich structure cage-type polysilsesquioxane are as follows: Under nitrogen protection, 19.8 g of phenyltrimethoxysilane, 2.7 g of sodium hydroxide, 100 mL of isopropanol and 5 mL of deionized water were added to a three-necked flask, stirred at room temperature until completely dissolved, heated to 90 ° C, stirred and refluxed for 4 h, cooled to room temperature and stirred for 15 h, filtered, repeatedly washed with isopropanol, and vacuum dried to obtain an incompletely condensed double-plywood structure cage-type polysilsesquioxane sodium salt; Under the protection of nitrogen, 5.8 g of incompletely condensed double-plywood cage-type polysilsesquioxane sodium salt, 1.5 mL of triethylamine and 50 mL of anhydrous tetrahydrofuran were added to a three-necked flask, stirred and dissolved under ice bath conditions for 2 h, and then 10 mL of anhydrous tetrahydrofuran solution containing 2.0 g of 3-isocyanatopropylmethyldichlorosilane was slowly added dropwise to the three-necked flask, the ice bath was removed, and the reaction was stirred at room temperature for 24 h, the solvent was removed by rotary evaporation, and the mixture was repeatedly washed with methanol and dried in vacuo to obtain terminal isocyanate phenyl double-plywood cage-type polysilsesquioxane; Under the protection of nitrogen, 3.3 g of terminal isocyanate phenyl double-plywood structure cage-type polysilsesquioxane and 50 mL of anhydrous tetrahydrofuran were added to a three-necked flask, and under the protection of nitrogen and mechanical stirring, 10 mL of anhydrous tetrahydrofuran solution containing 1.4 g of oleic acid and 5 mL of anhydrous tetrahydrofuran solution containing 0.8 g of 4-dimethylaminopyridine were sequentially added dropwise to the three-necked flask, the temperature was raised to 90° C., stirred and refluxed for reaction for 6 h, cooled to room temperature, the solvent was removed by rotary evaporation, and vacuum dried to obtain alkenyl phenyl double-plywood structure cage-type polysilsesquioxane; The nuclear magnetic resonance hydrogen spectrum of the alkenyl phenyl double-splint structure cage-type polysilsesquioxane is characterized as follows: 1 H NMR (DMSO-d 6 ,400MHz) δ: 0.09 (s, 6H), 0.81-0.85 (t, 6H), 0.91-0.94 (t, 4H), 1.20-1.33 (m, 40H), 1.57-1.77 (m, 16H), 2 .14-2.17(t, 4H), 3.11-3.16(m, 4H), 5.28-5.40(m, 4H), 7.33-7.54(m, 40H), 7.77-7.80(t, 2H). Embodiment 2:

[0021] A preparation process of a high-barrier high-temperature cooking-resistant packaging film I based on a single PP recyclable material, comprising the following steps: Step 1, preparing an olefinic phenyl double-sandwich structure cage-type polysilsesquioxane / graphene composite material: based on π-π stacking effect (between the benzene ring in the olefinic phenyl double-sandwich structure cage-type polysilsesquioxane and graphene oxide) and hydrogen bonding effect (between the amide group in the olefinic phenyl double-sandwich structure cage-type polysilsesquioxane and the hydroxyl / carboxyl group on the surface of graphene oxide), the olefinic phenyl double-sandwich structure cage-type polysilsesquioxane is compounded with graphene oxide to obtain an olefinic phenyl double-sandwich structure cage-type polysilsesquioxane / graphene composite material; The specific experimental steps for preparing the alkenylated phenyl double-sandwich structure cage-type polysilsesquioxane / graphene composite material are as follows: 6 g of graphene oxide powder (sheet diameter 3-10 μm, thickness 8-15 nm), 3 g of alkenylated phenyl double-sandwich structure cage-type polysilsesquioxane and 100 mL of anhydrous tetrahydrofuran are added into a beaker, ultrasonically treated for 30 min, heated to 60° C. and stirred for 5 h, centrifuged, repeatedly centrifuged and washed with deionized water, and vacuum dried to obtain the alkenylated phenyl double-sandwich structure cage-type polysilsesquioxane / graphene composite material; Step 2: preparing a high-barrier polypropylene-based composite material that is resistant to high temperatures and punctures: on the one hand, free radicals are generated by the polypropylene resin under the action of a peroxide initiator, and the alkenyl functional groups contained in the alkenyl phenyl double-sandwich structure cage-type polysilsesquioxane / graphene composite material are coupled with the free radicals in the polypropylene resin; on the other hand, the alkyl long chains contained in the alkenyl phenyl double-sandwich structure cage-type polysilsesquioxane / graphene composite material are used to perform molecular chain intercalation in the polypropylene resin to achieve modification of the polypropylene resin, thereby obtaining a high-barrier polypropylene-based composite material that is resistant to high temperatures and punctures; The peroxide initiator is one of dicumyl peroxide (DCP), tert-butyl hydroperoxide (TBHP), dibenzoyl peroxide (BPO), and tert-butyl perbenzoate (TBPB); dicumyl peroxide (DCP) is selected in this embodiment; The specific experimental steps for preparing a high-barrier polypropylene-based composite material that is resistant to high temperature and puncture are as follows: first, 9 g of polypropylene resin, 0.9 g of alkenyl phenyl double-ply structure cage-type polysilsesquioxane / graphene composite material, and 0.1 g of dicumyl peroxide initiator are added from a feed port to a twin-screw extruder, and a coupling reaction is carried out by high-temperature melt mixing, and the reaction is maintained for 10 minutes. The high-barrier polypropylene-based composite material that is resistant to high temperature and puncture is obtained by melt mixing in a twin-screw extruder for 30 minutes and extrusion granulation. Among them, the process parameters of the twin-screw extruder are set as follows: preheating temperature 180°C, temperatures of zones 1-6 are 180°C, 185°C, 190°C, 195°C, 205°C, 195°C, and rotation speed is 100r / min; Step 2, preparing a high-barrier and high-temperature cooking-resistant packaging film I based on a single PP recyclable material: according to the formula of the high-barrier and high-temperature cooking-resistant packaging film I based on a single PP recyclable material, the ingredients are prepared, and the raw materials of each layer are respectively put into the hoppers of the five screw extruders of the five-layer co-extrusion film blow molding unit, and the molten resin is merged at the head of the die through a diverter, extruded through the die head, blown and pulled (the blowing ratio is controlled at 2.6), cooled and rolled, and a high-barrier and high-temperature cooking-resistant packaging film I based on a single PP recyclable material with a thickness of 100 μm is prepared; Among them, the process parameters of the screw extruder corresponding to the first and fifth layers are set as follows: the temperatures of zones 1-3 are 120°C, 150°C, and 180°C, respectively, the flow channel temperature is 175°C, and the speed is 30r / min; The process parameters of the screw extruders corresponding to the second and fourth layers were set as follows: the temperatures of zones 1-3 were 120°C, 140°C, and 170°C, respectively, the flow channel temperature was 165°C, and the rotation speed was 20 r / min; The process parameters of the screw extruder corresponding to the third layer are set as follows: the temperatures of zones 1-3 are 150°C, 180°C, and 205°C, respectively, the flow channel temperature is 195°C, and the rotation speed is 50r / min. Embodiment three:

[0022] A high-barrier, high-temperature-resistant cooking packaging film II based on a single PP recyclable material, the product structure of which is different from the high-barrier, high-temperature-resistant cooking packaging film I based on a single PP recyclable material in Example 1 only in that: the formula of the high-barrier polypropylene-based composite material that is resistant to high temperature and puncture is: 90wt% polypropylene resin, 5wt% olefinic phenyl double-plywood structure cage-type polysilsesquioxane, 1wt% peroxide initiator and 4wt% graphene oxide; The preparation process of the high barrier and high temperature resistant cooking packaging film II based on a single PP recyclable material is the same as the preparation process of the high barrier and high temperature resistant cooking packaging film I based on a single PP recyclable material in Example 2. Embodiment 4:

[0023] A high-barrier, high-temperature-resistant cooking packaging film III based on a single PP recyclable material, the product structure of which is different from the high-barrier, high-temperature-resistant cooking packaging film I based on a single PP recyclable material in Example 1 only in that: the formula of the high-barrier polypropylene-based composite material that is resistant to high temperature and puncture is: 90wt% polypropylene resin, 1wt% olefinic phenyl double-plywood structure cage-type polysilsesquioxane, 1wt% peroxide initiator and 8wt% graphene oxide; The preparation process of the high barrier and high temperature resistant cooking packaging film III based on a single PP recyclable material is the same as the preparation process of the high barrier and high temperature resistant cooking packaging film I based on a single PP recyclable material in Example 2. Comparative Example:

[0024] Preparation of conventional polypropylene film: Compared with the high barrier and high temperature resistant cooking packaging film I based on a single PP recyclable material, the only difference is that the raw material of the third layer is polypropylene resin. Performance Testing:

[0025] (1) High temperature cooking resistance test: The high temperature cooking resistance test of the samples was carried out in accordance with GB / T 10004-2008 "Dry-process lamination and extrusion lamination of plastic composite films and bags for packaging". The specific test steps are as follows: Heat-seal the packaging film sample into a 200mm×120mm packaging bag, fill it with water to two-thirds of its volume, exhaust and seal it, put it in a high pressure sterilizer with a back pressure device, treat it at a temperature of 140℃ for 30 minutes, cool it to room temperature under reduced pressure and take it out, and check whether the packaging bag has obvious deformation, interlayer peeling, peeling of the heat-sealed part and other abnormal phenomena; (2) Barrier performance test: The oxygen permeability test and water vapor permeability test of the samples were carried out in accordance with GB / T 1038.1-2022 "Test method for gas permeability of plastic films and sheets - Part 1: Differential pressure method" and GB / T 1037-2021 "Determination of water vapor permeability of plastic films and sheets - Cup weight gain and weight loss method" respectively. The specific test steps are as follows: Place a 30 cm circular sample in a glass desiccator at an ambient temperature of 25°C and anhydrous calcium chloride as a desiccant for 72 hours, and then use a Y110 oxygen permeability tester and a TC-03 water vapor permeability tester to test the barrier properties of the samples; (3) Puncture resistance test: The puncture resistance test of the sample was carried out in accordance with GB / T 37841-2019 "Test method for puncture resistance of plastic film and sheeting". The specific test steps are as follows: a 5 cm × 5 cm film sample was fixed on the MCT-02A puncture strength tester. The puncture needle was made of stainless steel with a diameter of 1.0 mm. The tip of the puncture needle was hemispherical with a radius of 0.5 mm. The puncture rate was 50 mm / min. The puncture resistance of the sample was recorded. (4) Mechanical properties test: According to GB / T 1040.1-2018 "Determination of tensile properties of plastics", a 150 mm × 20 mm sample (sampled along the film blowing direction) was fixed on an Instron 5565 universal tensile testing machine at room temperature, and a tensile test was performed at a tensile rate of 100 mm / min, and the longitudinal tensile strength of the sample was recorded; (5) Heat sealing performance test: The samples were heat sealed using a HSG-C heat sealer with a sealing area of ​​15 cm × 1 cm, a heat sealing temperature of 135 °C, a heat sealing pressure of 0.2 MPa, and a heat sealing time of 2.0 s. According to QB / T 2358-1998 "Test Method for Heat Seal Strength of Plastic Film Packaging Bags", the heat seal performance of the heat seal sample was tested at a test speed of 300mm / min and a clamp spacing of 50mm. The heat seal strength of the sample was recorded. (6) Hygienic performance: The hygienic performance of the samples was tested in accordance with GB / T 5009.60-2003 "Analysis method for hygienic standards of polyethylene, polystyrene and polypropylene moldings for food packaging". The physical and chemical indicators of the experimental results were based on GB / T5009.71-2003 "Analysis method for hygienic standards of polypropylene resin for food packaging"; The above experimental results are shown in Tables 1-3 and Figure 3 .

[0026] Table 1 Performance test results of high barrier and high temperature cooking resistant packaging film based on single PP recyclable material

[0027] Table 2 Performance test results of high barrier and high temperature cooking resistant packaging film based on single PP recyclable material II

[0028] Table 3 Performance test results of high barrier and high temperature cooking resistant packaging film based on single PP recyclable material

[0029] Through comprehensive analysis of the above experimental results, the following conclusions can be drawn: Conclusion 1: The high-barrier high-temperature cooking-resistant packaging film based on a single PP recyclable material prepared by the present invention has no abnormal phenomena such as deformation, interlayer peeling and heat-sealed part peeling after being cooked at 140°C for 30 minutes, showing excellent high-temperature cooking resistance; Conclusion 2: The high-barrier high-temperature cooking-resistant packaging film prepared by the independently developed high-barrier polypropylene-based composite material that is resistant to high temperatures and punctures has achieved a beneficial technical effect of significantly improving the puncture resistance and barrier properties compared to the conventional polypropylene film prepared by conventional polypropylene resin; Conclusion 3: The high-barrier high-temperature cooking-resistant packaging film prepared by the present invention also has excellent mechanical properties and heat-sealing properties, and its hygienic properties meet the requirements of national standards, and can be used in high-temperature cooking-resistant food packaging.

Claims

1. A high barrier and high temperature resistant cooking packaging film based on a single PP recyclable material, characterized in that: The product structure of the film is the following layers arranged in sequence: PP layer / PP-g-MAH layer / functional layer / PP-g-MAH layer / MPP layer; PP layer: the raw material formula is 100wt% polypropylene resin, the dosage is 20-35 parts by weight; PP-g-MAH layer: the raw material formula is 100wt% maleic anhydride grafted polypropylene resin, the dosage is 3-10 parts by weight; MPP layer: the raw material formula is 100wt% metallocene polypropylene resin, the dosage is 20-35 parts by weight; Functional layer: The raw material formula is 100wt% of a high-barrier polypropylene-based composite material that is resistant to high temperatures and punctures, and the dosage is 20-35 parts by weight; The high-barrier polypropylene-based composite material that is resistant to high temperature and puncture is obtained by first compounding olefinic phenyl double-sandwich structure cage-type polysilsesquioxane with graphene oxide through π-π stacking and hydrogen bonding, and then loading it onto polypropylene resin through free radical coupling reaction and molecular chain intercalation.

2. According to claim 1, a high barrier and high temperature resistant retort packaging film based on a single PP recyclable material, characterized in that: The formula of the high-barrier polypropylene-based composite material that is resistant to high temperature and puncture is 85-90wt% of polypropylene resin, 1-8wt% of olefinic phenyl double-sandwich structure cage-type polysilsesquioxane, 0.5-2wt% of peroxide initiator and 3-10wt% of graphene oxide.

3. The high-barrier, high-temperature-resistant cooking packaging film based on a single PP recyclable material according to claim 2, characterized in that: The chemical structural formula of the alkenylated phenyl double-ply structure cage-type polysilsesquioxane is: 。 4. The high-barrier, high-temperature-resistant retort packaging film based on a single PP recyclable material according to claim 3, characterized in that: The preparation method of the alkenylated phenyl double-sandwich structure cage-type polysilsesquioxane is as follows: Phenyltrimethoxysilane is used as a raw material, and a hydrolysis-condensation method is adopted to catalyze the hydrolysis and polycondensation reaction of phenyltrimethoxysilane with sodium hydroxide to generate an incompletely condensed double-sandwich structure cage-type polysilsesquioxane sodium salt; The isocyanate-terminated phenyl double-sandwich cage-type polysilsesquioxane was synthesized by the vertex-capping method using incompletely condensed double-sandwich cage-type polysilsesquioxane sodium salt as raw material and 3-isocyanatopropylmethyldichlorosilane as capping agent under the catalysis of triethylamine. By utilizing the nucleophilic addition reaction mechanism, under the catalytic action of an organic base catalyst, the isocyanate group of the terminal isocyanate phenyl double-sandwich structure cage-type polysilsesquioxane undergoes a decarboxylation condensation reaction with the carboxyl functional group of oleic acid to generate an olefinic phenyl double-sandwich structure cage-type polysilsesquioxane.

5. The high-barrier, high-temperature-resistant cooking packaging film based on a single PP recyclable material according to claim 4, characterized in that: The organic base catalyst is one of triethylamine, triethylenediamine, pyridine and 4-dimethylaminopyridine.

6. The high barrier and high temperature resistant cooking packaging film based on a single PP recyclable material according to claim 1, characterized in that: The preparation method of the high-barrier polypropylene-based composite material that is resistant to high temperature and puncture is as follows: Step 1: Based on π-π stacking and hydrogen bonding, alkenyl phenyl double-sandwich structure cage-type polysilsesquioxane is compounded with graphene oxide to obtain an alkenyl phenyl double-sandwich structure cage-type polysilsesquioxane / graphene composite material; Step 2: Based on the free radical coupling reaction mechanism under the action of peroxide initiator and molecular chain intercalation technology, the polypropylene resin is modified using an olefinic phenyl double-sandwich structure cage-type polysilsesquioxane / graphene composite material, and extruded and granulated using a twin-screw extruder to obtain a high-barrier polypropylene-based composite material that is resistant to high temperature and puncture.

7. The high-barrier, high-temperature-resistant retort packaging film based on a single PP recyclable material according to claim 6, characterized in that: The graphene oxide has a sheet diameter of 3-10 μm and a thickness of 8-15 nm.

8. The high-barrier, high-temperature-resistant retort packaging film based on a single PP recyclable material according to claim 6, characterized in that: The peroxide initiator is one of dicumyl peroxide, tert-butyl hydroperoxide, dibenzoyl peroxide and tert-butyl perbenzoate.

9. The high-barrier, high-temperature-resistant cooking packaging film based on a single PP recyclable material according to claim 1, characterized in that: The thickness of the high-barrier high-temperature cooking-resistant packaging film is 50-150 μm.

10. A high barrier and high temperature resistant cooking packaging film based on a single PP recyclable material according to any one of claims 1 to 9, characterized in that: The high-barrier high-temperature cooking-resistant packaging film is used under the condition of a temperature of ≤140°C.

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