Food packaging box and manufacturing process thereof

Abstract

The invention discloses a food packaging box and a manufacturing process thereof, and relates to the technical field of packaging materials. The food packaging box is prepared from the following components in parts by weight: 45 to 65 parts of polypropylene, 20 to 35 parts of polylactic acid, 8 to 16 parts of food-grade paraffin, 6 to 15 parts of modified montmorillonite, 3 to 8 parts of 3-glycidyl ether oxypropyl trimethoxy silane, 5 to 10 parts of chitosan phosphate, 3 to 8 parts of sorbitan fatty acid ester and 2 to 6 parts of tri (2, 4-di-tert-butylphenyl) phosphite. The prepared food packaging box has excellent barrier property, can effectively prevent permeation of moisture and gas, and delays oxidative deterioration of food; meanwhile, the long-lasting antibacterial activity is achieved, the growth of microorganisms can be effectively inhibited, and the shelf life of food is remarkably prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of packaging materials, and in particular to a food packaging box and a manufacturing process thereof. Background Art

[0002] With the improvement of living standards and the rapid development of the food industry, food packaging materials are playing an increasingly important role in ensuring food safety, extending shelf life and improving storage and transportation conditions. Ideal food packaging materials should have excellent mechanical properties, good barrier properties, antibacterial properties and environmental friendliness. At present, food packaging materials mainly include traditional petroleum-based materials, bio-based materials and various composite materials.

[0003] Traditional food packaging materials are mainly petroleum-based polymers such as polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET). These materials have excellent processing properties, good mechanical strength and low cost, but they have problems such as heavy environmental burden and insufficient barrier properties. Taking polyethylene as an example, its barrier properties to water vapor and oxygen are poor, which can easily cause the food in the package to become damp or oxidized and deteriorate. Although polypropylene has good heat resistance and chemical stability, its gas barrier properties are also difficult to meet the packaging requirements for fresh food.

[0004] With the increasing awareness of environmental protection, bio-based materials represented by polylactic acid (PLA), starch-based materials and cellulose derivatives have gradually attracted attention. These materials are renewable and biodegradable, but generally have disadvantages such as poor mechanical properties and high cost. Among them, polylactic acid, as one of the most promising bio-based materials, has shortcomings such as high brittleness and poor gas barrier properties. In addition, its surface hydrophobicity is strong, which is not conducive to the uniform dispersion of functional additives such as antibacterial agents, limiting its wide application in the field of food packaging.

[0005] In order to improve the performance defects of a single material, researchers have developed a variety of composite modification schemes. Among them, layered silicates represented by montmorillonite have shown obvious advantages in improving the barrier properties and mechanical properties of composite materials due to their unique layered structure and large specific surface area.

[0006] CN109021416A discloses a food composite packaging material and a preparation method thereof. The material is prepared from the following raw materials in parts by weight: 25-36 parts of polystyrene resin, 18-32 parts of polypropylene carbonate, 12-20 parts of alkyd resin, 5-12 parts of polypropylene glycol diglycidyl ether, 8-12 parts of calcium phosphate, 3-6 parts of polyacetimide, 8-14 parts of polylactic acid, 5-9 parts of propylene glycol methyl ether, 3-8 parts of polyacrylonitrile fiber, 5-12 parts of montmorillonite, 5-8 parts of oleic acid, 6-10 parts of polymethacrylic acid, 2-6 parts of dichlorodifluoromethane, 2-4 parts of polyether sulfone, 3-7 parts of plasticizer, 2-7 parts of cyclophosphamide, and 1-3 parts of sodium dibutylnaphthalene sulfonate.

[0007] However, the surface of natural montmorillonite is highly hydrophilic, has poor compatibility with the hydrophobic polymer matrix, is easily aggregated, and is difficult to achieve uniform dispersion in the matrix.

[0008] There are two major outstanding problems with the food packaging materials currently on the market: first, the barrier properties are insufficient. Most packaging materials have poor barrier effects on small molecules such as water vapor and oxygen, which makes the food in the package susceptible to moisture and oxidation, affecting the quality of the food; second, the lack of antibacterial properties. The surface of the packaging material is prone to breeding bacteria and fungi, which accelerates the spoilage of food and shortens the shelf life. Although the antibacterial properties of the material can be improved by adding antibacterial agents, the existing antibacterial agents have poor dispersion and insufficient durability in the polymer matrix, and some antibacterial agents have potential food safety risks.

[0009] Therefore, developing a green food packaging material with excellent barrier properties, good mechanical properties, lasting antibacterial properties and biodegradability is of great significance to promoting the sustainable development of the food packaging industry. Summary of the invention

[0010] In order to solve the deficiencies in the prior art, the purpose of the present invention is to provide a food packaging box and a manufacturing process thereof. The prepared food packaging box has excellent barrier properties, can effectively prevent the penetration of moisture and gas, and delay the oxidation and deterioration of food; at the same time, it has long-lasting antibacterial activity, can effectively inhibit the growth of microorganisms, and significantly extend the shelf life of food.

[0011] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a food packaging box is made of the following components, measured by weight: 45-65 parts of polypropylene, 20-35 parts of polylactic acid, 8-16 parts of food-grade paraffin, 6-15 parts of modified montmorillonite, 3-8 parts of 3-glycidyloxypropyltrimethoxysilane, 5-10 parts of chitosan phosphate, 3-8 parts of sorbitan fatty acid ester, and 2-6 parts of tris(2,4-di-tert-butylphenyl)phosphite.

[0012] Preferably, the preparation method of the modified montmorillonite comprises the following steps: (1) dispersing montmorillonite in deionized water, ultrasonically treating, adding 2,3-dimercaptosuccinic acid, adjusting the pH of the system, stirring the reaction, filtering, washing, and drying the product to obtain mercapto-montmorillonite; Acid-catalyzed esterification reaction: First, montmorillonite is ultrasonically dispersed in water to form a stable colloid, exposing a large number of surface hydroxyl groups (Si-OH). Under acidic conditions, the carboxyl group (-COOH) of 2,3-dimercaptosuccinic acid undergoes a condensation reaction with the hydroxyl groups on the surface of montmorillonite. The protonated carboxyl carbon atom is nucleophilically attacked by the hydroxyl groups on the surface of montmorillonite, and finally dehydrates to form an ester bond (Si-OC=O) through a tetrahedral intermediate, while retaining the thiol group (-SH) in the molecule.

[0013] Preferably, in step (1), the usage ratio of montmorillonite, deionized water and 2,3-dimercaptosuccinic acid is 10 g: 100-150 mL: 2-5 g.

[0014] Preferably, in step (1), the ultrasonic treatment is performed for 10 to 30 minutes; the pH of the system is adjusted to 4 to 6 with hydrochloric acid; and the stirring reaction conditions are 60 to 75° C. and the stirring reaction is performed for 4 to 8 hours.

[0015] (2) dispersing the thiolated montmorillonite in tetrahydrofuran, adding 1-allyl-1,1,3,3-tetramethyldisiloxane and AIBN in sequence, stirring and reacting under an inert atmosphere, filtering, washing and drying the product to obtain siloxane-modified montmorillonite; Free radical-induced thiol-olefin addition reaction: Thiolated montmorillonite dispersed in tetrahydrofuran reacts with 1-allyl-1,1,3,3-tetramethyldisiloxane. AIBN decomposes under heating conditions to produce free radicals, which initiate thiol (-SH) to produce thiol radicals (-S·). The thiol radical attacks the double bond of the organosilicon olefin to form a carbon radical intermediate, which continues to extract a hydrogen atom from another thiol to form a stable thioether bond (-S-CH 2 -), while regenerating sulfur free radicals to maintain the chain reaction. The reaction is carried out under an inert atmosphere to avoid oxygen quenching free radicals and affecting the reaction.

[0016] Preferably, in step (2), the usage ratio of mercapto montmorillonite, tetrahydrofuran, 1-allyl-1,1,3,3-tetramethyldisiloxane and AIBN is 10 g: 80-120 mL: 3.4-5.2 g: 0.05-0.2 g.

[0017] Preferably, in step (2), the stirring reaction conditions are 50-65° C. for 3-7 hours; and the product is washed with tetrahydrofuran and deionized water for 3-5 times in sequence.

[0018] (3) Dispersing the siloxane-modified montmorillonite in toluene, adding agmatine and Speier catalyst, stirring and reacting under an inert atmosphere, filtering, washing, and drying the product to obtain modified montmorillonite.

[0019] Platinum-catalyzed hydrosilation reaction: Si-H bonds have been introduced on the surface of siloxane-modified montmorillonite through the first two steps. 2 PtCl 6 ) reacts with agmatine. The reaction mechanism involves the reduction of Pt(IV) to an active Pt(II) species, which first undergoes oxidative addition to the Si-H bond and then coordinates to the amino group in the agmatine molecule. Migration insertion then occurs, followed by reduction elimination to obtain a Si-N bond, while releasing hydrogen and allowing the catalyst to circulate. The entire process achieves covalent attachment of the guanidine group to the montmorillonite surface via a stable Si-N bond.

[0020] Preferably, in step (3), the amount ratio of siloxane montmorillonite, toluene, agmatine, and Speier catalyst is 10 g: 80-120 mL: 3-5 g: 0.05-0.3 mL; the Speier catalyst is 0.1 mol / L H 2 PtCl 6 Isopropyl alcohol solution.

[0021] Preferably, in step (3), the stirring reaction conditions are 70-85° C. for 6-12 h; and the product is washed with toluene and deionized water for 3-5 times in sequence.

[0022] The present invention also claims protection for a production process of the food packaging box, comprising the following steps: uniformly mixing the raw materials in a high-speed mixer to obtain a mixture, obtaining a powder by melt extrusion, cooling, pelletizing, drying, and grinding, extruding the powder through a sheet extruder to obtain a sheet, and molding the sheet using a food packaging box molding machine to obtain the food packaging box.

[0023] Preferably, the raw materials are mixed at 250-400 r / min and 60-70° C. for 3-8 min; melt-extruded at 180-200° C.; and extruded into a sheet at 200-230° C.

[0024] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a food packaging box, wherein polypropylene as the main material provides good mechanical strength and processing performance, polylactic acid gives the material biodegradability, food-grade paraffin as a lubricating agent improves the fluidity and demoulding performance of the material, modified montmorillonite significantly improves the barrier and mechanical properties of the material, 3-glycidyloxypropyltrimethoxysilane as a coupling agent improves the organic-inorganic compatibility, chitosan phosphate has an antibacterial effect and can extend the shelf life of food, sorbitan fatty acid ester as an emulsifier improves the compatibility of each component, and tris (2,4-di-tert-butylphenyl) phosphite as an antioxidant improves the stability of the material. Through the optimized ratio of each component, the prepared food packaging box has excellent mechanical properties, barrier properties, antibacterial properties and biodegradability, meeting the strict requirements of food packaging.

[0025] 2. The present invention provides a modified montmorillonite, which gradually introduces different functional groups on the surface of montmorillonite to achieve efficient and multifunctional modification. First, 2,3-dimercaptosuccinic acid reacts with the hydroxyl groups on the surface of montmorillonite to obtain thiol groups on the surface of montmorillonite. These active thiol groups provide important reaction sites for subsequent organic modification. Secondly, 1-allyl-1,1,3,3-tetramethyldisiloxane is grafted onto the surface of montmorillonite through a thiol-olefin addition reaction. The introduced long-chain siloxane groups significantly improve the hydrophobicity of montmorillonite, which not only weakens the polar interaction between montmorillonite layers, but also facilitates the dispersion of montmorillonite in non-polar polymer matrices such as polypropylene. Its hydrophobic properties can also effectively block the penetration of water molecules. Finally, agmatine is grafted onto the surface of montmorillonite through a hydrosilylation reaction. The guanidine group has a broad-spectrum antibacterial effect, which can effectively inhibit the growth of bacteria and fungi and improve the antiseptic and fresh-keeping effect of food packaging materials. This multi-level modification enables montmorillonite to obtain good dispersion in the polymer matrix, forming a nano-scale exfoliation structure, and significantly improving the mechanical properties of the composite material by increasing the specific surface area. At the same time, the exfoliated layered silicate forms a tortuous diffusion path (maze effect) in the matrix, and cooperates with the hydrophobic barrier effect of the surface siloxane groups. Through the synergistic effect of physical blocking and chemical repulsion, it effectively extends the diffusion path of water molecules and gas molecules, and significantly enhances the barrier properties of the material. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0027] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased from commercial sources or synthesized from raw materials purchased from commercial sources.

[0028] Polypropylene was purchased from Dongguan Kunhe Plastic Chemical Co., Ltd. with the brand name T03; Polylactic acid was purchased from Dongguan Hesheng Plastic Co., Ltd., model number Fengyuan FY201; The montmorillonite is sodium montmorillonite purchased from Shanghai Yuanye Biotechnology Co., Ltd. with a specific surface area of ​​240 m 2 / kg, item number is S42017.

[0029] A process for making a food packaging box comprises the following steps: (1) Disperse 10 g of montmorillonite in 100-150 mL of deionized water, perform ultrasonic treatment for 10-30 min, add 2-5 g of 2,3-dimercaptosuccinic acid, adjust the pH of the system to 4-6 with hydrochloric acid, stir and react at 60-75 °C for 4-8 h, filter, wash and dry the product to obtain thiolated montmorillonite; (2) Disperse 10 g of mercapto-modified montmorillonite in 80-120 mL of tetrahydrofuran, add 3.4-5.2 g of 1-allyl-1,1,3,3-tetramethyldisiloxane and 0.05-0.2 g of AIBN in sequence, stir and react for 3-7 h at 50-65 °C in an inert atmosphere, filter the product, wash it with tetrahydrofuran and deionized water for 3-5 times in sequence, and dry it to obtain siloxane-modified montmorillonite; (3) Disperse 10 g of siloxane-modified montmorillonite in 80-120 mL of toluene, add 3-5 g of agmatine and 0.05-0.3 mL of 0.1 mol / L H 2 PtCl 6 isopropanol solution, reacting under inert atmosphere at 70-85°C with stirring for 6-12h, filtering the product, washing with toluene and deionized water for 3-5 times, and drying to obtain modified montmorillonite; (4) 45-65 parts of polypropylene, 20-35 parts of polylactic acid, 8-16 parts of food-grade paraffin, 6-15 parts of modified montmorillonite, 3-8 parts of 3-glycidyloxypropyltrimethoxysilane, 5-10 parts of chitosan phosphate, 3-8 parts of sorbitan fatty acid ester and 2-6 parts of tris(2,4-di-tert-butylphenyl)phosphite are mixed in a high-speed mixer at 250-400 r / min and 60-70° C. for 3-8 min to obtain a mixture, which is melt-extruded at 180-200° C., cooled, pelletized, dried and ground to obtain a powder, which is extruded through a sheet extruder at 200-230° C. to obtain a sheet, which is molded using a food packaging box molding machine to obtain the food packaging box.

[0030] The present invention will be further described below through specific embodiments. Example 1

[0031] A process for making a food packaging box comprises the following steps: (1) Disperse 10 g of montmorillonite in 150 mL of deionized water, perform ultrasonic treatment for 30 min, add 5 g of 2,3-dimercaptosuccinic acid, adjust the pH of the system to 5 with hydrochloric acid, react at 75 °C with stirring for 4 h, filter, wash and dry the product to obtain mercapto montmorillonite; (2) Disperse 10 g of mercapto-modified montmorillonite in 100 mL of tetrahydrofuran, add 5.2 g of 1-allyl-1,1,3,3-tetramethyldisiloxane and 0.2 g of AIBN in sequence, stir and react for 3 h at 65 °C in an inert atmosphere, filter the product, wash it four times with tetrahydrofuran and deionized water in sequence, and dry it to obtain siloxane-modified montmorillonite; (3) Disperse 10 g of siloxane-modified montmorillonite in 100 mL of toluene, add 5 g of agmatine and 0.3 mL of 0.1 mol / L H 2 PtCl 6 isopropanol solution, stirred and reacted at 85°C in an inert atmosphere for 6 h, the product was filtered, washed with toluene and deionized water 4 times in sequence, and dried to obtain modified montmorillonite; (4) 650 g of polypropylene, 350 g of polylactic acid, 160 g of food-grade paraffin, 150 g of modified montmorillonite, 80 g of 3-glycidyloxypropyltrimethoxysilane, 100 g of chitosan phosphate, 80 g of sorbitan fatty acid ester and 60 g of tri(2,4-di-tert-butylphenyl)phosphite were mixed in a high-speed mixer at 300 r / min and 65° C. for 5 min to obtain a mixture, which was melt-extruded at 190° C., cooled, pelletized, dried and ground to obtain a powder, which was extruded through a sheet extruder at 220° C. to obtain a sheet, which was molded using a food packaging box molding machine to obtain the food packaging box. Example 2

[0032] A process for making a food packaging box comprises the following steps: (1) Disperse 10 g of montmorillonite in 150 mL of deionized water, perform ultrasonic treatment for 30 min, add 4 g of 2,3-dimercaptosuccinic acid, adjust the pH of the system to 5 with hydrochloric acid, react at 70 ° C with stirring for 5 h, filter, wash and dry the product to obtain thiolated montmorillonite; (2) Disperse 10 g of mercapto-modified montmorillonite in 100 mL of tetrahydrofuran, add 4.4 g of 1-allyl-1,1,3,3-tetramethyldisiloxane and 0.15 g of AIBN in sequence, stir and react for 4 h at 60 °C in an inert atmosphere, filter the product, wash it four times with tetrahydrofuran and deionized water in sequence, and dry it to obtain siloxane-modified montmorillonite; (3) Disperse 10 g of siloxane-modified montmorillonite in 100 mL of toluene, add 4 g of agmatine and 0.2 mL of 0.1 mol / L H 2 PtCl6 isopropanol solution, stirred and reacted at 80°C in an inert atmosphere for 8 h, the product was filtered, washed with toluene and deionized water 4 times in sequence, and dried to obtain modified montmorillonite; (4) 600 g of polypropylene, 300 g of polylactic acid, 120 g of food-grade paraffin, 120 g of modified montmorillonite, 60 g of 3-glycidyloxypropyltrimethoxysilane, 80 g of chitosan phosphate, 60 g of sorbitan fatty acid ester and 50 g of tri(2,4-di-tert-butylphenyl)phosphite were mixed in a high-speed mixer at 300 r / min and 65° C. for 5 min to obtain a mixture, which was melt-extruded at 190° C., cooled, pelletized, dried and ground to obtain a powder, which was extruded through a sheet extruder at 220° C. to obtain a sheet, which was molded using a food packaging box molding machine to obtain the food packaging box. Example 3

[0033] A process for making a food packaging box comprises the following steps: (1) Disperse 10 g of montmorillonite in 150 mL of deionized water, perform ultrasonic treatment for 30 min, add 3 g of 2,3-dimercaptosuccinic acid, adjust the pH of the system to 5 with hydrochloric acid, stir and react at 65 °C for 6 h, filter, wash and dry the product to obtain thiolated montmorillonite; (2) Disperse 10 g of mercapto-modified montmorillonite in 100 mL of tetrahydrofuran, add 4.0 g of 1-allyl-1,1,3,3-tetramethyldisiloxane and 0.1 g of AIBN in sequence, stir and react for 6 h at 55 °C in an inert atmosphere, filter the product, wash it four times with tetrahydrofuran and deionized water in sequence, and dry it to obtain siloxane-modified montmorillonite; (3) Disperse 10 g of siloxane-modified montmorillonite in 100 mL of toluene, add 4 g of agmatine and 0.1 mL of 0.1 mol / L H 2 PtCl 6 isopropanol solution, stirred and reacted at 75°C in an inert atmosphere for 10 h, the product was filtered, washed with toluene and deionized water four times in sequence, and dried to obtain modified montmorillonite; (4) 550 g of polypropylene, 250 g of polylactic acid, 100 g of food-grade paraffin, 80 g of modified montmorillonite, 50 g of 3-glycidyloxypropyltrimethoxysilane, 60 g of chitosan phosphate, 50 g of sorbitan fatty acid ester and 40 g of tris(2,4-di-tert-butylphenyl)phosphite were mixed in a high-speed mixer at 300 r / min and 65° C. for 5 min to obtain a mixture, which was melt-extruded at 190° C., cooled, pelletized, dried and ground to obtain a powder, which was extruded through a sheet extruder at 220° C. to obtain a sheet, which was molded using a food packaging box molding machine to obtain the food packaging box. Example 4

[0034] A process for making a food packaging box comprises the following steps: (1) Disperse 10 g of montmorillonite in 150 mL of deionized water, perform ultrasonic treatment for 30 min, add 2 g of 2,3-dimercaptosuccinic acid, adjust the pH of the system to 5 with hydrochloric acid, react at 60 ° C with stirring for 8 h, filter, wash and dry the product to obtain thiolated montmorillonite; (2) Disperse 10 g of mercapto-modified montmorillonite in 100 mL of tetrahydrofuran, add 3.4 g of 1-allyl-1,1,3,3-tetramethyldisiloxane and 0.05 g of AIBN in sequence, stir and react for 7 h at 50 °C in an inert atmosphere, filter the product, wash it four times with tetrahydrofuran and deionized water in sequence, and dry it to obtain siloxane-modified montmorillonite; (3) Disperse 10 g of siloxane-modified montmorillonite in 100 mL of toluene, add 3 g of agmatine and 0.05 mL of 0.1 mol / L H 2 PtCl 6 isopropanol solution, stirred and reacted at 70°C in an inert atmosphere for 12 h, the product was filtered, washed with toluene and deionized water four times in sequence, and dried to obtain modified montmorillonite; (4) 450 g of polypropylene, 200 g of polylactic acid, 80 g of food-grade paraffin, 60 g of modified montmorillonite, 30 g of 3-glycidyloxypropyltrimethoxysilane, 50 g of chitosan phosphate, 30 g of sorbitan fatty acid ester and 20 g of tris(2,4-di-tert-butylphenyl)phosphite were mixed in a high-speed mixer at 300 r / min and 65° C. for 5 min to obtain a mixture, which was melt-extruded at 190° C., cooled, pelletized, dried and ground to obtain a powder, which was extruded through a sheet extruder at 220° C. to obtain a sheet, which was molded using a food packaging box molding machine to obtain the food packaging box.

[0035] Comparative Example 1: A process for making a food packaging box, comprising the following steps: (1) Disperse 10 g of montmorillonite in 150 mL of deionized water, perform ultrasonic treatment for 30 min, add 5 g of 2,3-dimercaptosuccinic acid, adjust the pH of the system to 5 with hydrochloric acid, react at 75 °C with stirring for 4 h, filter, wash and dry the product to obtain mercapto montmorillonite; (2) Disperse 10 g of mercapto-modified montmorillonite in 100 mL of tetrahydrofuran, add 5.2 g of 1-allyl-1,1,3,3-tetramethyldisiloxane and 0.2 g of AIBN in sequence, stir and react for 3 h at 65 °C in an inert atmosphere, filter the product, wash it four times with tetrahydrofuran and deionized water in sequence, and dry it to obtain siloxane-modified montmorillonite; (3) 650 g of polypropylene, 350 g of polylactic acid, 160 g of food-grade paraffin, 150 g of siloxane-modified montmorillonite, 80 g of 3-glycidyloxypropyltrimethoxysilane, 100 g of chitosan phosphate, 80 g of sorbitan fatty acid ester and 60 g of tris(2,4-di-tert-butylphenyl)phosphite were mixed in a high-speed mixer at 300 r / min and 65° C. for 5 min to obtain a mixture, which was melt-extruded at 190° C., cooled, pelletized, dried and ground to obtain a powder, which was extruded through a sheet extruder at 220° C. to obtain a sheet, which was molded using a food packaging box molding machine to obtain the food packaging box.

[0036] Comparative Example 2: A process for making a food packaging box, comprising the following steps: (1) Disperse 10 g of montmorillonite in 150 mL of deionized water, perform ultrasonic treatment for 30 min, add 5 g of 2,3-dimercaptosuccinic acid, adjust the pH of the system to 5 with hydrochloric acid, react at 75 °C with stirring for 4 h, filter, wash and dry the product to obtain mercapto montmorillonite; (2) 650 g of polypropylene, 350 g of polylactic acid, 160 g of food-grade paraffin, 150 g of mercapto-montmorillonite, 80 g of 3-glycidyloxypropyltrimethoxysilane, 100 g of chitosan phosphate, 80 g of sorbitan fatty acid ester and 60 g of tris(2,4-di-tert-butylphenyl)phosphite were mixed in a high-speed mixer at 300 r / min and 65° C. for 5 min to obtain a mixture, which was melt-extruded at 190° C., cooled, pelletized, dried and ground to obtain a powder, which was extruded through a sheet extruder at 220° C. to obtain a sheet, which was molded using a food packaging box molding machine to obtain the food packaging box.

[0037] The food packaging boxes prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were subjected to performance tests. The tensile strength was tested with reference to GB / T1040.3-2006 "Determination of tensile properties of plastics Part 3: Test conditions for films and sheets". The experimental temperature was 23°C and the humidity was 65%. A type 2 specimen was used, the specimen width was 10 mm, the thickness was 0.8 mm, the gauge length was 50 mm, and the experimental no-load speed was 500 mm / min. The impact resistance was tested with reference to GB / T 21189-2007 "Testing of pendulum impact testers for simply supported beams, cantilever beams and tensile impact tests of plastics". The experimental temperature was 23°C and the humidity was 65%. The samples were made into long strips of 60 mm×10 mm×3 mm. The antibacterial performance was tested with reference to the film method in GB / T 21510-2008 "Testing methods for antibacterial properties of nano-inorganic materials". The specimen size was 50 mm×50 mm×4 mm. The total number of bacterial colonies was determined with reference to GB 4789.2-2010 "National Food Safety Standard - Determination of Total Colony Count for Food Microbiological Examination", the detection bacteria are Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 6538; refer to GB / T 19789-2021 "Oxygen Permeability Test for Plastic Film and Sheet for Packaging Materials - Coulometric Test Method" to test its oxygen barrier performance; select strawberries with good appearance and no damage, put 20 in each box, seal them with an ultrasonic box-stitching machine after packing, and store them at 20℃ and 85% humidity. Count the number of days required for all the strawberries in the box to rot and mold, and test its freshness preservation performance; specific data are shown in Table 1.

[0038] Table 1 Food packaging box performance test results

[0039] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A food packaging box, characterized in that: The invention is made of the following components in parts by weight: 45-65 parts of polypropylene, 20-35 parts of polylactic acid, 8-16 parts of food-grade paraffin, 6-15 parts of modified montmorillonite, 3-8 parts of 3-glycidyloxypropyltrimethoxysilane, 5-10 parts of chitosan phosphate, 3-8 parts of sorbitan fatty acid ester and 2-6 parts of tris(2,4-di-tert-butylphenyl)phosphite.

2. The food packaging box according to claim 1, characterized in that: The preparation method of the modified montmorillonite comprises the following steps: (1) dispersing montmorillonite in deionized water, ultrasonically treating, adding 2,3-dimercaptosuccinic acid, adjusting the pH of the system, stirring the reaction, filtering, washing, and drying the product to obtain mercapto-montmorillonite; (2) dispersing the thiolated montmorillonite in tetrahydrofuran, adding 1-allyl-1,1,3,3-tetramethyldisiloxane and AIBN in sequence, stirring and reacting under an inert atmosphere, filtering, washing and drying the product to obtain siloxane-modified montmorillonite; (3) Dispersing the siloxane-modified montmorillonite in toluene, adding agmatine and Speier catalyst, stirring and reacting under an inert atmosphere, filtering, washing, and drying the product to obtain modified montmorillonite.

3. The food packaging box according to claim 2, characterized in that: In step (1), the usage ratio of montmorillonite, deionized water and 2,3-dimercaptosuccinic acid is 10 g: 100-150 mL: 2-5 g.

4. The food packaging box according to claim 2, characterized in that: In step (1), ultrasonic treatment is performed for 10 to 30 minutes; the pH value of the system is adjusted to 4 to 6 with hydrochloric acid; and the stirring reaction conditions are 60 to 75° C. and the stirring reaction is performed for 4 to 8 hours.

5. The food packaging box according to claim 2, characterized in that: In step (2), the usage ratio of mercapto montmorillonite, tetrahydrofuran, 1-allyl-1,1,3,3-tetramethyldisiloxane and AIBN is 10 g: 80-120 mL: 3.4-5.2 g: 0.05-0.2 g.

6. The food packaging box according to claim 2, characterized in that: In step (2), the stirring reaction conditions are 50-65° C. for 3-7 hours; the product is washed with tetrahydrofuran and deionized water for 3-5 times in sequence.

7. The food packaging box according to claim 2, characterized in that: In step (3), the dosage ratio of siloxane montmorillonite, toluene, agmatine and Speier catalyst is 10 g: 80-120 mL: 3-5 g: 0.05-0.3 mL; the Speier catalyst is a 0.1 mol / L H2PtCl6 isopropanol solution.

8. The food packaging box according to claim 2, characterized in that: In step (3), the stirring reaction conditions are 70-85° C. for 6-12 hours; the product is washed with toluene and deionized water for 3-5 times in sequence.

9. A process for manufacturing a food packaging box according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: uniformly mixing the raw materials in a high-speed mixer to obtain a mixture, performing melt extrusion, cooling, pelletizing, drying and grinding to obtain a powder, extruding the powder through a sheet extruder to obtain a sheet, and molding the sheet through a food packaging box molding machine to obtain the food packaging box.

10. The manufacturing process according to claim 9, characterized in that: The raw materials are mixed at 250-400 r / min and 60-70°C for 3-8 minutes; melt-extruded at 180-200°C; and extruded into sheets at 200-230°C.

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