Fresh fruit and vegetable fresh-keeping packaging material adopting composite stone-plastic box-nuclear track membrane-graphene technology

Abstract

The invention relates to the technical field of fruit and vegetable fresh-keeping, and discloses a fresh fruit and vegetable fresh-keeping packaging material adopting a composite stone-plastic box-nuclear track membrane-graphene technology, and the fresh fruit and vegetable fresh-keeping packaging material is prepared by the following method: mixing polyester resin, modified calcium carbonate and a plasticizer, stirring to form a mixture, and carrying out extrusion molding on the mixture to obtain a stone-plastic box matrix; the PET polyester film is subjected to heavy ion irradiation, and a PET polyester nuclear track film is obtained; mixing the composite antibacterial material, tetraethoxysilane, polyester resin, deionized water and ethanol, and uniformly stirring to obtain a graphene antibacterial compound; the preparation method comprises the following steps: coating a stone-plastic box matrix with an adhesive, laminating a PET polyester nuclear track film, carrying out hot pressing, spraying the graphene antibacterial compound, and curing to obtain the fresh-keeping packaging material. The fresh-keeping packaging material comprises a stone-plastic box base body formed by polyester and modified calcium carbonate, a PET polyester film serves as a modified atmosphere layer, a graphene antibacterial compound serves as an antibacterial layer, and the good antibacterial performance and compressive strength are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of fresh fruit and vegetable preservation, and specifically to a fresh fruit and vegetable preservation packaging material combining composite stone plastic box - nuclear pore membrane - graphene technology. Background Art

[0002] During the fresh - keeping storage of fruits and vegetables, due to the high water content of fruits and vegetables, tender tissues, high field heat and respiratory heat after harvesting, rapid water evaporation, fruits and vegetables are extremely prone to yellowing and rotting, with a short shelf life and easy rotting during logistics transportation. Therefore, fruits and vegetables need to be preserved. Currently, most of the fresh - keeping packaging materials used on the market are polyvinyl chloride, polypropylene and polyvinylidene fluoride packaging materials. These packaging materials are prone to phenomena such as condensation during storage and transportation, resulting in the rotting of fruits and vegetables.

[0003] Mixing PET polyester (polyethylene terephthalate) and calcium carbonate to form a stone plastic box as the matrix of the fresh - keeping packaging material for fruits and vegetables has heat - resistance, moisture - proof and waterproof properties, and has a good fresh - keeping effect for fruits and vegetables. However, calcium carbonate is prone to agglomeration, forming stress concentration points, resulting in a decrease in the compressive strength of the fresh - keeping packaging material for fruits and vegetables, and poor antibacterial performance, affecting the storage effect of fruits and vegetables. In addition, the existing technology lacks a solution for the synergy of modified atmosphere - antibacterial - earthquake resistance, resulting in a high loss rate during the storage of fruits and vegetables. Summary of the Invention

[0004] The present invention provides a fresh fruit and vegetable preservation packaging material combining composite stone plastic box - nuclear pore membrane - graphene technology, which solves the problems of poor antibacterial and compressive strength of existing fresh - keeping packaging materials for fruits and vegetables.

[0005] The technical solution of the present invention: A preparation method of a fresh fruit and vegetable preservation packaging material combining composite stone plastic box - nuclear pore membrane - graphene technology, comprising the following preparation steps: S1. Mix polyester resin, modified calcium carbonate and a plasticizer, stir to form a mixture, place the mixture in a mold, and obtain a stone plastic box matrix through extrusion and shaping; S2. Irradiate a PET polyester film with heavy ions to obtain a PET polyester nuclear pore membrane; S3. Mix a composite antibacterial material, tetraethyl orthosilicate, polyester resin, deionized water and ethanol, and stir evenly to obtain a graphene antibacterial composite; S4. Coat an adhesive on the stone plastic box matrix, bond the PET polyester nuclear pore membrane, after hot pressing, then spray the graphene antibacterial composite, and after curing, obtain the preservation packaging material; The modified calcium carbonate is obtained by depositing nano - calcium carbonate on the surface of pretreated carbon fiber, and then mixing and reacting with ethylene glycol and terephthalic acid; The composite antibacterial material is obtained by mixing and reacting modified graphene oxide, gum, carboxymethyl cellulose and sericin powder; The modified graphene oxide is obtained by mixing and reacting copper sulfate pentahydrate, graphene oxide and L-ascorbic acid, and then reacting with naringin and a coupling agent.

[0006] Further, in step S1, the stirring temperature is 150 - 160 °C, the stirring rate is 7000 - 8000 r / min, the stirring time is 10 - 15 min; the mold temperature is 180 - 190 °C.

[0007] Further, in step S1, the mass ratio of the polyester resin, modified calcium carbonate and plasticizer is (50 - 60):(30 - 40):(1 - 2).

[0008] Further, in step S2, the heavy ion irradiation process: using the Lanzhou Heavy Ion Research Facility, a 129Xe ion beam with an energy of 80 MeV / u, and an irradiation fluence of 1×10 11 ions / cm 2 ².

[0009] Further, in step S3, the dosage ratio of the composite antibacterial material, tetraethyl orthosilicate, polyester resin, deionized water and ethanol is (2 - 3) g:(5 - 6) g:(45 - 55) g:(40 - 50) mL:(45 - 55) mL.

[0010] Further, in step S4, the hot pressing process: the hot pressing temperature is 165 - 175 °C, the hot pressing pressure is 10 - 15 MPa, and the hot pressing time is 10 - 20 min.

[0011] Further, in step S4, the spraying pressure is 0.2 - 0.4 MPa, the curing temperature is 100 - 120 °C, and the curing time is 20 - 30 min.

[0012] Further, the thickness of the stone plastic box substrate is 2 - 3 mm.

[0013] Further, the thickness of the PET polyester film is 45 - 55 μm.

[0014] Further, the thickness of the graphene antibacterial composite coating is 45 - 55 μm.

[0015] Further, the polyester resin is selected from any one of polyethylene terephthalate, polylactic acid, and polybutylene terephthalate.

[0016] Further, the adhesive is a cyanoacrylate adhesive, brand ODAKE / Oudake, Dongguan Hexu Xinwang Adhesive Co., Ltd.

[0017] Further, the plasticizer is selected from any one of epoxidized soybean oil, triethyl citrate, glycerol, and polyethylene glycol.

[0018] Further, the composite antibacterial material is specifically prepared by the following steps: A1. Add graphene oxide to deionized water, stir evenly, add copper sulfate, after ultrasonic treatment, add L-ascorbic acid, react at 30 - 40 °C for 1 - 2 h, filter, wash, and dry to obtain graphene oxide loaded with nano copper. A2. Add naringin to ethanol and deionized water, stir evenly, add a coupling agent, stir and react at 70 - 80 °C for 1 - 2 h, add graphene oxide loaded with nano copper and hydrochloric acid, continue to stir for 20 - 30 min, filter, wash, and dry to obtain modified graphene oxide. A3. Add the modified graphene oxide to deionized water, stir evenly, add gum and glycerol, perform ultrasonic treatment at 40 - 60 KHz for 10 - 20 min, and dry until the moisture evaporates to obtain a gum-modified graphene oxide composite material. A4. Add sericin powder, the gum-modified graphene oxide composite material, and carboxymethyl cellulose to deionized water, stir and react at 45 - 50 °C for 40 - 50 min, and perform freeze-drying to obtain the composite antibacterial material.

[0019] Further, during the above A1 reaction process, a large number of oxygen-containing functional groups are present on the surface of graphene oxide, which can combine with copper ions in copper sulfate pentahydrate, causing the copper ions to deposit on graphene oxide. L-ascorbic acid, as a reducing agent, can reduce the copper ions to nano copper particles, realizing the formation of uniformly distributed nano copper on the surface of graphene oxide to obtain graphene oxide loaded with nano copper.

[0020] Further, during the above A2 reaction process, the silanol groups generated by the hydrolysis of the coupling agent can react with the hydroxyl groups on the surface of graphene oxide loaded with nano copper, and the amino groups carried by the coupling agent can be chemically bonded to the oxygen-containing functional groups in naringin, causing naringin to be coated on the surface of graphene oxide loaded with nano copper to obtain modified graphene oxide.

[0021] Further, during the above A3 reaction process, the naringin on the surface of the modified graphene oxide binds to the hydroxyl and carboxyl groups in the gum molecular chain through hydrogen bonds, causing the modified graphene oxide to be uniformly dispersed in the gum, and the polysaccharide chain segments of the gum are inserted into the interlayers of the modified graphene oxide sheets to form a layered gum-modified graphene oxide composite material.

[0022] Furthermore, during the above A4 reaction process, the sericin powder forms a sericin solution after heating. The hydroxyl and carboxyl groups contained therein can chemically bond with carboxymethyl cellulose to form a gel with a crosslinked network structure. Moreover, the gum-modified graphene oxide composite can also be embedded in the gel with the crosslinked network structure to obtain a composite antibacterial material.

[0023] Furthermore, in step A1, the dosage ratio of graphene oxide, deionized water, copper sulfate, and L-ascorbic acid is (1 - 2) g : (180 - 220) mL : (2 - 3) g : (1 - 1.2) g.

[0024] Furthermore, in step A2, the dosage ratio of naringin, ethanol, deionized water, coupling agent, graphene oxide loaded with nano copper, and hydrochloric acid is (1.3 - 1.5) g : (25 - 35) mL : (8 - 12) mL : (0.4 - 0.6) g : (2.5 - 2.9) g : (0.4 - 0.6) mL.

[0025] Furthermore, in step A3, the dosage ratio of modified graphene oxide, deionized water, gum, and glycerol is (2 - 3) g : (90 - 110) mL : (1.1 - 1.3) g : (0.4 - 1.6) g.

[0026] Furthermore, in step A4, the dosage ratio of sericin powder, gum-modified graphene oxide composite, carboxymethyl cellulose, and deionized water is (8 - 9) g : (2 - 3) g : (1.2 - 1.4) g : (45 - 55) mL.

[0027] Furthermore, the modified calcium carbonate is specifically prepared by the following steps: B1. Add the pretreated carbon fiber into deionized water, stir evenly, add nano calcium carbonate, after ultrasonic treatment, filter, wash, and dry to obtain carbon fiber loaded with nano calcium carbonate; B2. Add the carbon fiber loaded with nano calcium carbonate into ethylene glycol, stir at 165 - 175 °C for 3 - 5 h, add terephthalic acid and antimony trioxide, stir evenly, react at 220 - 240 °C and 0.4 - 0.6 MPa for 30 - 40 min, cool to room temperature, take out, wash, and dry to obtain modified nano calcium carbonate.

[0028] Furthermore, during the above B1 reaction process, the pretreated carbon fiber has excellent adhesion and contains a large number of phenolic hydroxyl groups, enabling nano calcium carbonate to deposit on the surface of the pretreated carbon fiber to obtain carbon fiber loaded with nano calcium carbonate.

[0029] Furthermore, in the above B2 reaction process, the carbon fiber loaded with nano-calcium carbonate is in ethylene glycol, and antimony trioxide is used as a catalyst. Ethylene glycol and terephthalic acid carry out a polycondensation reaction to form polyethylene terephthalate on the surface of the carbon fiber loaded with nano-calcium carbonate, obtaining modified calcium carbonate.

[0030] Furthermore, in step B1, the dosage ratio of the pretreated carbon fiber, deionized water, and nano-calcium carbonate is (5 - 6) g : (90 - 110) mL : (1 - 2) g.

[0031] Furthermore, in step B2, the mass ratio of the carbon fiber loaded with nano-calcium carbonate, ethylene glycol, terephthalic acid, and antimony trioxide is (2 - 3) : (6 - 8) : (15 - 17) : (1.1 - 1.3).

[0032] Furthermore, the nanoparticles are selected from any one of nano-silica, nano-aluminum oxide, and nano-magnesium oxide.

[0033] The present invention has the following beneficial effects: (1) In the technical solution of the present invention, nano-copper is formed on the surface of graphene oxide. Graphene oxide serves as a carrier for nano-copper, enabling the uniform distribution of nano-copper on the surface of graphene oxide, avoiding the aggregation of nano-copper. Moreover, graphene oxide and nano-copper, as inorganic antibacterial materials, have good antibacterial activity. Naringin is coated on the surface of graphene oxide loaded with nano-copper through a coupling agent. On the one hand, naringin interacts with the microbial membrane, promoting the leakage of intracellular components, being able to prevent bacteria from passing through the plastic-based film, having antibacterial activity, and naringin and graphene oxide loaded with nano-copper form an organic-inorganic antibacterial material, enhancing the antibacterial activity of the fruit and vegetable fresh-keeping packaging material. On the other hand, naringin forms a flexible protective film on the surface of graphene oxide loaded with nano-copper, avoiding the large hardness of graphene oxide loaded with nano-copper from damaging the antibacterial coating of the fresh-keeping packaging material and resulting in a decline in the antibacterial performance of the fresh-keeping packaging material.

[0034] (2) In the technical solution of the present invention, the modified graphene oxide and the gum form a layered structure. On the one hand, the polysaccharide segments of the gum are inserted between the nanosheets of the modified graphene oxide to form a layered structure with alternating organic and inorganic connections, which can reduce the water vapor transmission rate and improve the antibacterial activity. On the other hand, the layered structure with alternating organic and inorganic connections can absorb external stress and enhance the compressive strength of the fresh-keeping packaging material. Mixing the gum-modified graphene oxide composite material, carboxymethyl cellulose and sericin powder to form an aerogel structure with a cross-linked network structure. On the one hand, the gum-modified graphene oxide composite material is dispersed in the sericin gel system, enhancing the adsorption and fixation of the modified graphene oxide and avoiding the easy migration and precipitation of the inorganic antibacterial material under the action of external force, which affects the antibacterial activity. On the other hand, the gum-modified graphene oxide increases the cross-linking density of the sericin gel, improves the mechanical strength of the sericin gel, and further enhances the compressive strength of the fresh-keeping packaging material.

[0035] (3) In the technical solution of the present invention, nano-calcium carbonate is deposited on the surface of the pretreated carbon fiber. On the one hand, the nano-calcium carbonate forms a concavo-convex structure on the surface of the pretreated carbon fiber, increasing the contact area with the stone plastic box matrix, so that the carbon fiber loaded with nano-calcium carbonate can better act in the polyester stone plastic box. On the other hand, the excellent aspect ratio of the carbon fiber can form a transition layer that absorbs gravity in the stone plastic box matrix, thereby weakening the stress generated by external force and enhancing the compressive strength of the fruit and vegetable fresh-keeping packaging material. Polyethylene terephthalate is formed on the surface of the carbon fiber loaded with nano-calcium carbonate to obtain modified calcium carbonate. The formed polyester structure has excellent compatibility with the polyester stone plastic box, and the modified calcium carbonate can form strong hydrogen bonds with the polyester stone plastic box matrix, so that the modified calcium carbonate is evenly dispersed in the polyester stone plastic box matrix to form a cross-linked network structure, enhancing the compressive strength of the polyester stone plastic box.

[0036] (4) In the technical solution of the present invention, using polyethylene terephthalate and modified calcium carbonate to form a stone plastic box as the matrix of the fresh-keeping packaging material, which has excellent compressive strength; the PET polyester film with a nuclear pore structure is used as the gas modulation layer of the fresh-keeping packaging material, significantly improving the CO2 / O2 exchange ratio of the fresh-keeping packaging material and having a good storage effect on fruits and vegetables; the composite antibacterial material, tetraethyl orthosilicate and polyethylene terephthalate are used as the graphene antibacterial layer of the fresh-keeping packaging material, which can significantly improve the antibacterial performance and compressive strength of the fresh-keeping packaging material, keep the fresh-keeping packaging material in a nuclear pore structure, and improve the CO2 / O2 exchange ratio of the fresh-keeping packaging material. Specific embodiments

[0037] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0038] The raw materials used in the embodiments of the present invention are as follows, and all the reagents used are of analytical grade.

[0039] Among them, the polyester resin is polyethylene terephthalate, with the product number P875573, purchased from Shanghai Macklin Biochemical Technology Co., Ltd.; the plasticizer is epoxy soybean oil, industrial grade, brand Kexing, purchased from Shandong Kexing Chemical Co., Ltd.

[0040] The PET polyester film is purchased from Tianjin Deli Film Co., Ltd.

[0041] The adhesive is cyanoacrylate adhesive, brand ODAKE / Oudake, from Dongguan Hexu Xinwang Adhesive Co., Ltd.

[0042] The coupling agent is γ-aminopropyltriethoxysilane; the gum is gum arabic.

[0043] The sericin powder is purchased from Wuhan Huaxiang Kejie Biotechnology Co., Ltd.

[0044] The particle size of graphene oxide is 2.5 μm; the length of carbon fiber is 5 μm, and the diameter is 100 nm; the particle size of nano calcium carbonate is 60 nm.

[0045] The pretreated carbon fiber is specifically prepared by the following steps: Add 2 g of carbon fiber to 100 mL of deionized water, stir evenly, add 0.4 g of Tris-HCl buffer solution with a pH of 8.5 and 0.7 g of dopamine, stir and react at 30 °C and 2000 r / min for 2 h, filter, wash twice with ethanol, and dry in an oven at 70 °C for 10 min to obtain the pretreated carbon fiber.

[0046] Example 1 A preparation method of a fresh fruit and vegetable fresh-keeping packaging material combining composite stone plastic box-nuclear pore membrane-graphene technology, comprising the following preparation steps: S1. Mix polyethylene terephthalate, modified calcium carbonate and epoxy soybean oil, stir to form a mixture, place the mixture in a mold, and obtain a stone plastic box matrix through extrusion and shaping; among them, the mass ratio of polyester resin, modified calcium carbonate and epoxy soybean oil is 50:30:1; S2. Irradiate the PET polyester film with heavy ions to obtain a PET polyester nuclear pore membrane; among them, the heavy ion irradiation process: use the Lanzhou Heavy Ion Research Facility, a 129Xe ion beam with an energy of 80 MeV / u, and an irradiation fluence of 1×10 11 ions / cm 2 ; S3. Mix the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water, and ethanol, and stir evenly to obtain a graphene antibacterial composite; among them, the dosage ratio of the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water, and ethanol is 2 g:5 g:45 g:40 mL:45 mL; S4. Apply 10 g of cyanoacrylate adhesive to the stone plastic box substrate, attach the PET polyester nuclear pore membrane, after hot pressing, then spray the graphene antibacterial composite, and after curing, obtain the fresh-keeping packaging material; among them, the hot pressing process: the hot pressing temperature is 165 °C, the hot pressing pressure is 10 MPa, and the hot pressing time is 10 min; the spraying pressure is 0.2 MPa, the curing temperature is 100 °C, and the curing time is 20 min; The thickness of the stone plastic box substrate is 2 mm; the thickness of the PET polyester film is 45 μm; the thickness of the graphene antibacterial composite coating is 45 μm.

[0047] The composite antibacterial material is specifically prepared by the following steps: A1. Add 1 g of graphene oxide to 180 mL of deionized water, stir evenly, add 2 g of copper sulfate, perform ultrasonic mixing treatment at 50 KHz for 30 min, add 1 g of L-ascorbic acid, react at 30 °C for 1 h, filter, wash with deionized water 3 times, and dry in an oven at 60 °C for 12 h to obtain graphene oxide loaded with nano-copper; A2. Add 1.3 g of naringin to 25 mL of ethanol and 8 mL of deionized water, stir evenly, add 0.4 g of γ-aminopropyltriethoxysilane, stir and react at 70 °C for 1 h, add 2.5 g of graphene oxide loaded with nano-copper and 0.4 mL of hydrochloric acid with a concentration of 0.1 mol / L, continue to stir for 20 min, filter, wash with deionized water 3 times, and dry in an oven at 60 °C for 15 min to obtain modified graphene oxide; A3. Add 2 g of modified graphene oxide to 90 mL of deionized water, stir evenly, add 1.1 g of gum arabic and 0.4 g of glycerol, perform ultrasonic treatment at 40 KHz for 10 min, and dry at 100 °C until the water evaporates to obtain a gum-modified graphene oxide composite material; A4. Add 8 g of sericin powder, 2 g of gum-modified graphene oxide composite, and 1.2 g of carboxymethyl cellulose to 45 mL of deionized water, stir and react at 45 °C for 40 min, place it in a freezer, and freeze-dry at -20 °C for 20 h to obtain the composite antibacterial material.

[0048] The modified calcium carbonate is specifically prepared by the following steps: B1. Add 5 g of pretreated carbon fiber to 90 mL of deionized water, stir evenly, add 1 g of nano calcium carbonate, ultrasonically treat at 50 KHz for 1.5 h, filter, wash with deionized water 3 times, and dry in an oven at 80 °C for 10 min to obtain carbon fiber loaded with nano calcium carbonate; B2. Add 2 g of carbon fiber loaded with nano calcium carbonate to 6 g of ethylene glycol, stir at 165 °C for 3 h, add 15 g of terephthalic acid and 1.1 g of antimony trioxide, stir evenly, react at 220 °C and 0.4 MPa for 30 min, cool to room temperature, take out, wash with deionized water 3 times, and dry in an oven at 70 °C for 10 min to obtain modified nano calcium carbonate.

[0049] Example 2 A preparation method of a fresh fruit and vegetable fresh-keeping packaging material combining composite stone plastic box-nuclear pore membrane-graphene technology, comprising the following preparation steps: S1. Mix polyethylene terephthalate, modified calcium carbonate, and epoxy soybean oil, stir to form a mixture, place the mixture in a mold, and extrude and shape to obtain a stone plastic box matrix; wherein, the mass ratio of polyester resin, modified calcium carbonate, and epoxy soybean oil is 55:35:1.5; S2. Irradiate the PET polyester film with heavy ions to obtain a PET polyester nuclear pore membrane; wherein, the heavy ion irradiation process: use the Lanzhou Heavy Ion Research Facility, a 129Xe ion beam with an energy of 80 MeV / u, and an irradiation fluence of 1×10 11 ions / cm 2 ; S3. Mix the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water, and ethanol, stir evenly to obtain a graphene antibacterial composite; wherein, the dosage ratio of the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water, and ethanol is 2.5 g:5.5 g:50 g:45 mL:50 mL; S4. Coat 10 g of cyanoacrylate adhesive on the stone plastic box matrix, bond the PET polyester nuclear pore membrane, after hot pressing, then spray the graphene antibacterial composite, and after curing, obtain the fresh-keeping packaging material; wherein, the hot pressing process: the hot pressing temperature is 170 °C, the hot pressing pressure is 13 MPa, and the hot pressing time is 15 min; the spraying pressure is 0.3 MPa, the curing temperature is 110 °C, and the curing time is 25 min; The thickness of the stone plastic box substrate is 2.5 mm; the thickness of the PET polyester film is 50 μm; the thickness of the graphene antibacterial composite coating is 50 μm.

[0050] The composite antibacterial material is specifically prepared by the following steps: A1. Add 1.5 g of graphene oxide to 200 mL of deionized water, stir evenly, add 2.5 g of copper sulfate, perform ultrasonic mixing treatment at 50 KHz for 30 min, add 1.1 g of L-ascorbic acid, react at 35 °C for 1.5 h, filter, wash with deionized water 3 times, and dry in an oven at 60 °C for 12 h to obtain graphene oxide loaded with nano-copper. A2. Add 1.4 g of naringin to 30 mL of ethanol and 10 mL of deionized water, stir evenly, add 0.5 g of γ-aminopropyltriethoxysilane, stir and react at 75 °C for 1.5 h, add 2.7 g of graphene oxide loaded with nano-copper and 0.5 mL of hydrochloric acid with a concentration of 0.1 mol / L, continue to stir for 25 min, filter, wash with deionized water 3 times, and dry in an oven at 60 °C for 15 min to obtain modified graphene oxide. A3. Add 2.5 g of modified graphene oxide to 100 mL of deionized water, stir evenly, add 1.2 g of gum arabic and 0.5 g of glycerol, perform ultrasonic treatment at 50 KHz for 15 min, and dry at 100 °C until the water evaporates to obtain a gum-modified graphene oxide composite material. A4. Add 8.5 g of sericin powder, 2.5 g of the gum-modified graphene oxide composite material, and 1.3 g of carboxymethyl cellulose to 50 mL of deionized water, stir and react at 48 °C for 45 min, place in a freezer, and freeze-dry at -20 °C for 20 h to obtain the composite antibacterial material.

[0051] The modified calcium carbonate is specifically prepared by the following steps: B1. Add 5.6 g of pretreated carbon fiber to 100 mL of deionized water, stir evenly, add 1.5 g of nano-calcium carbonate, perform ultrasonic treatment at 50 KHz for 1.5 h, filter, wash with deionized water 3 times, and dry in an oven at 80 °C for 10 min to obtain carbon fiber loaded with nano-calcium carbonate. B2. Add 2.6 g of carbon fiber loaded with nano-calcium carbonate to 7 g of ethylene glycol, stir at 170 °C for 4 h, add 16 g of terephthalic acid and 1.2 g of antimony trioxide, stir evenly, react at 230 °C and 0.5 MPa for 35 min, cool to room temperature, take out, wash with deionized water 3 times, and dry in an oven at 70 °C for 10 min to obtain modified nano-calcium carbonate.

[0052] Example 3 A preparation method of a fresh fruit and vegetable fresh-keeping packaging material combining stone plastic box, nuclear pore membrane and graphene technology, comprising the following preparation steps: S1. Mix polyethylene terephthalate, modified calcium carbonate and epoxidized soybean oil, stir to form a mixture, place the mixture in a mold, and obtain a stone plastic box matrix through extrusion and shaping; among them, the mass ratio of polyester resin, modified calcium carbonate and epoxidized soybean oil is 60:40:2; S2. Irradiate the PET polyester film with heavy ions to obtain a PET polyester nuclear pore membrane; among them, the heavy ion irradiation process: use the Lanzhou Heavy Ion Research Facility, a 129Xe ion beam with an energy of 80 MeV / u, and an irradiation fluence of 1×10 11 ions / cm 2 ; S3. Mix the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water and ethanol, and stir evenly to obtain a graphene antibacterial composite; among them, the dosage ratio of the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water and ethanol is 3g:6g:55g:50mL:55mL; S4. Apply 12 g of cyanoacrylate adhesive on the stone plastic box matrix, laminate the PET polyester nuclear pore membrane, after hot pressing, then spray the graphene antibacterial composite, and after curing, obtain the fresh-keeping packaging material; among them, the hot pressing process: the hot pressing temperature is 175 °C, the hot pressing pressure is 15 MPa, and the hot pressing time is 20 min; the spraying pressure is 0.4 MPa, the curing temperature is 120 °C, and the curing time is 30 min; The thickness of the stone plastic box matrix is 3 mm; the thickness of the PET polyester film is 55 μm; the thickness of the graphene antibacterial composite coating is 55 μm.

[0053] The composite antibacterial material is specifically prepared by the following steps: A1. Add 2 g of graphene oxide to 220 mL of deionized water, stir evenly, add 3 g of copper sulfate, perform ultrasonic mixing treatment at 50 KHz for 30 min, add 1.2 g of L-ascorbic acid, react at 40 °C for 2 h, filter, wash with deionized water 3 times, and dry in an oven at 60 °C for 12 h to obtain copper-loaded graphene oxide; A2. Add 1.5 g of naringin to 35 mL of ethanol and 12 mL of deionized water, stir evenly, add 0.6 g of γ-aminopropyltriethoxysilane, stir and react at 80 °C for 2 h, add 2.9 g of copper-loaded graphene oxide and 0.6 mL of hydrochloric acid with a concentration of 0.1 mol / L, continue to stir for 30 min, filter, wash with deionized water 3 times, and dry in an oven at 60 °C for 15 min to obtain modified graphene oxide; A3. Add 3 g of modified graphene oxide to 110 mL of deionized water, stir evenly, add 1.3 g of gum arabic and 0.6 g of glycerol, ultrasonically treat for 20 min at 60 KHz, and dry at 100 °C until the water evaporates to obtain a gum-modified graphene oxide composite material; A4. Add 9 g of sericin powder, 3 g of gum-modified graphene oxide composite material and 1.4 g of carboxymethyl cellulose to 55 mL of deionized water, stir and react at 50 °C for 50 min, place it in a freezer, and freeze-dry at -20 °C for 20 h to obtain a composite antibacterial material.

[0054] The modified calcium carbonate is specifically prepared by the following steps: B1. Add 6 g of pretreated carbon fiber to 110 mL of deionized water, stir evenly, add 2 g of nano calcium carbonate, ultrasonically treat for 1.5 h at 50 KHz, filter, wash 3 times with deionized water, and dry in an 80 °C oven for 10 min to obtain carbon fiber loaded with nano calcium carbonate; B2. Add 3 g of carbon fiber loaded with nano calcium carbonate to 8 g of ethylene glycol, stir at 175 °C for 5 h, add 17 g of terephthalic acid and 1.3 g of antimony trioxide, stir evenly, react at 240 °C and 0.6 MPa for 40 min, cool to room temperature, take out, wash 3 times with deionized water, and dry in a 70 °C oven for 10 min to obtain modified nano calcium carbonate.

[0055] Comparative Example 1 A preparation method of a fresh fruit and vegetable preservation packaging material combining composite stone plastic box-nuclear pore membrane-graphene technology includes the following preparation steps: S1. Mix polyethylene terephthalate, modified calcium carbonate and epoxy soybean oil, stir to form a mixture, place the mixture in a mold, and extrude and shape to obtain a stone plastic box matrix; among them, the mass ratio of polyester resin, modified calcium carbonate and epoxy soybean oil is 60:40:2; S2. Irradiate the PET polyester film with heavy ions to obtain a PET polyester nuclear pore membrane; among them, the heavy ion irradiation process: use the Lanzhou Heavy Ion Research Facility, a 129Xe ion beam with an energy of 80 MeV / u, and an irradiation fluence of 1×10 11 ions / cm 2 ; S3. Mix the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water and ethanol, and stir evenly to obtain a graphene antibacterial composite; among them, the dosage ratio of the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water and ethanol is 3 g:6 g:55 g:50 mL:55 mL; S4. Apply 12 g of cyanoacrylate adhesive on the stone plastic box substrate, bond the PET polyester nuclear pore membrane, after hot pressing, then spray the graphene antibacterial composite, and after curing, obtain the fresh-keeping packaging material; among them, the hot pressing process: the hot pressing temperature is 175 °C, the hot pressing pressure is 15 MPa, and the hot pressing time is 20 min; the spraying pressure is 0.4 MPa, the curing temperature is 120 °C, and the curing time is 30 min; The thickness of the stone plastic box substrate is 3 mm; the thickness of the PET polyester film is 55 μm; the thickness of the graphene antibacterial composite coating is 55 μm.

[0056] The composite antibacterial material is specifically prepared by the following steps: A1. Add 1.5 g of naringin to 35 mL of ethanol and 12 mL of deionized water, stir evenly, add 0.6 g of γ-aminopropyltriethoxysilane, stir and react at 80 °C for 2 h, add 2.9 g of graphene oxide and 0.6 mL of hydrochloric acid with a concentration of 0.1 mol / L, continue to stir for 30 min, filter, wash with deionized water 3 times, and dry in an oven at 60 °C for 15 min to obtain modified graphene oxide; A2. Add 3 g of modified graphene oxide to 110 mL of deionized water, stir evenly, add 1.3 g of gum arabic and 0.6 g of glycerol, ultrasonically treat at 60 KHz for 20 min, and dry at 100 °C until the water evaporates to obtain the gum-modified graphene oxide composite material; A3. Add 9 g of sericin powder, 3 g of the gum-modified graphene oxide composite material and 1.4 g of carboxymethyl cellulose to 55 mL of deionized water, stir and react at 50 °C for 50 min, place in a freezer, and freeze-dry at -20 °C for 20 h to obtain the composite antibacterial material.

[0057] The modified calcium carbonate is specifically prepared by the following steps: B1. Add 6 g of pretreated carbon fiber to 110 mL of deionized water, stir evenly, add 2 g of nano calcium carbonate, ultrasonically treat at 50 KHz for 1.5 h, filter, wash with deionized water 3 times, and dry in an oven at 80 °C for 10 min to obtain carbon fiber loaded with nano calcium carbonate; B2. Add 3 g of carbon fiber loaded with nano calcium carbonate to 8 g of ethylene glycol, stir at 175 °C for 5 h, add 17 g of terephthalic acid and 1.3 g of antimony trioxide, stir evenly, react at 240 °C and 0.6 MPa for 40 min, cool to room temperature, take out, wash with deionized water 3 times, and dry in an oven at 70 °C for 10 min to obtain modified nano calcium carbonate.

[0058] Comparative Example 2 A preparation method of a fresh fruit and vegetable fresh-keeping packaging material with a composite stone plastic box-nuclear pore membrane-graphene technology, comprising the following preparation steps: S1. Mix polyethylene terephthalate, modified calcium carbonate and epoxidized soybean oil, stir to form a mixed material, place the mixed material in a mold, and obtain a stone plastic box matrix through extrusion and shaping; among them, the mass ratio of polyester resin, modified calcium carbonate and epoxidized soybean oil is 60:40:2; S2. Irradiate the PET polyester film with heavy ions to obtain a PET polyester nuclear pore membrane; among them, the heavy ion irradiation process: use the Lanzhou Heavy Ion Research Facility, the 129Xe ion beam with an energy of 80 MeV / u, and the irradiation fluence is 1×10 11 ions / cm 2 ; S3. Mix the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water and ethanol, and stir evenly to obtain a graphene antibacterial composite; among them, the dosage ratio of the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water and ethanol is 3g:6g:55g:50mL:55mL; S4. Apply 12 g of cyanoacrylate adhesive on the stone plastic box matrix, bond the PET polyester nuclear pore membrane, after hot pressing, then spray the graphene antibacterial composite, and after curing, obtain the fresh-keeping packaging material; among them, the hot pressing process: the hot pressing temperature is 175 °C, the hot pressing pressure is 15 MPa, and the hot pressing time is 20 min; the spraying pressure is 0.4 MPa, the curing temperature is 120 °C, and the curing time is 30 min; The thickness of the stone plastic box matrix is 3 mm; the thickness of the PET polyester film is 55 μm; the thickness of the graphene antibacterial composite coating is 55 μm.

[0059] The composite antibacterial material is specifically prepared by the following steps: A1. Add 2 g of graphene oxide to 220 mL of deionized water, stir evenly, add 3 g of copper sulfate, perform ultrasonic mixing treatment at 50 KHz for 30 min, add 1.2 g of L-ascorbic acid, react at 40 °C for 2 h, filter, wash with deionized water 3 times, and dry in an oven at 60 °C for 12 h to obtain graphene oxide loaded with nano-copper; A2. Add 3 g of graphene oxide loaded with nano-copper to 110 mL of deionized water, stir evenly, add 1.3 g of gum arabic and 0.6 g of glycerol, perform ultrasonic treatment at 60 KHz for 20 min, and dry at 100 °C until the water volatilizes to obtain a gum-graphene oxide composite material; A3. Add 9 g of sericin powder, 3 g of the gum-graphene oxide composite material and 1.4 g of carboxymethyl cellulose to 55 mL of deionized water, stir and react at 50 °C for 50 min, place it in a freezer, and freeze-dry at -20 °C for 20 h to obtain the composite antibacterial material.

[0060] The modified calcium carbonate is specifically prepared by the following steps: B1. Add 6 g of pretreated carbon fiber into 110 mL of deionized water, stir evenly, add 2 g of nano calcium carbonate, perform ultrasonic treatment at 50 KHz for 1.5 h, filter, wash with deionized water three times, and dry in an oven at 80 °C for 10 min to obtain carbon fiber loaded with nano calcium carbonate; B2. Add 3 g of carbon fiber loaded with nano calcium carbonate into 8 g of ethylene glycol, stir at 175 °C for 5 h, add 17 g of terephthalic acid and 1.3 g of antimony trioxide, stir evenly, react at 240 °C and 0.6 MPa for 40 min, cool to room temperature, take out, wash with deionized water three times, and dry in an oven at 70 °C for 10 min to obtain modified nano calcium carbonate.

[0061] Comparative Example 3 A preparation method of a fresh fruit and vegetable preservation packaging material combining a composite stone plastic box - nuclear pore membrane - graphene technology, comprising the following preparation steps: S1. Mix polyethylene terephthalate, modified calcium carbonate, and epoxy soybean oil, stir to form a mixture, place the mixture in a mold, and perform extrusion molding to obtain a stone plastic box matrix; wherein, the mass ratio of polyester resin, modified calcium carbonate, and epoxy soybean oil is 60:40:2; S2. Irradiate the PET polyester film with heavy ions to obtain a PET polyester nuclear pore membrane; wherein, the heavy ion irradiation process: use the Lanzhou Heavy Ion Research Facility, a 129Xe ion beam with an energy of 80 MeV / u, and an irradiation fluence of 1×10 11 ions / cm 2 ; S3. Mix the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water, and ethanol, stir evenly to obtain a graphene antibacterial composite; wherein, the dosage ratio of the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water, and ethanol is 3 g:6 g:55 g:50 mL:55 mL; S4. Coat 12 g of cyanoacrylate adhesive on the stone plastic box matrix, attach the PET polyester nuclear pore membrane, after hot pressing, then spray the graphene antibacterial composite, and after curing, obtain the preservation packaging material; wherein, the hot pressing process: the hot pressing temperature is 175 °C, the hot pressing pressure is 15 MPa, and the hot pressing time is 20 min; the spraying pressure is 0.4 MPa, the curing temperature is 120 °C, and the curing time is 30 min; The thickness of the stone plastic box matrix is 3 mm; the thickness of the PET polyester film is 55 μm; the thickness of the graphene antibacterial composite coating is 55 μm.

[0062] The composite antibacterial material is specifically prepared by the following steps: A1. Add 2 g of graphene oxide to 220 mL of deionized water, stir evenly, add 3 g of copper sulfate, ultrasonically mix and process at 50 KHz for 30 min, add 1.2 g of L-ascorbic acid, react at 40 °C for 2 h, filter, wash with deionized water 3 times, and dry in an oven at 60 °C for 12 h to obtain graphene oxide loaded with nano-copper; A2. Add 1.5 g of naringin to 35 mL of ethanol and 12 mL of deionized water, stir evenly, add 0.6 g of γ-aminopropyltriethoxysilane, stir and react at 80 °C for 2 h, add 2.9 g of graphene oxide loaded with nano-copper and 0.6 mL of hydrochloric acid with a concentration of 0.1 mol / L, continue to stir for 30 min, filter, wash with deionized water 3 times, and dry in an oven at 60 °C for 15 min to obtain modified graphene oxide; A3. Add 9 g of sericin powder, 3 g of modified graphene oxide and 1.4 g of carboxymethyl cellulose to 55 mL of deionized water, stir and react at 50 °C for 50 min, place in a freezer, and freeze-dry at -20 °C for 20 h to obtain a composite antibacterial material.

[0063] The modified calcium carbonate is specifically prepared by the following steps: B1. Add 6 g of pretreated carbon fiber to 110 mL of deionized water, stir evenly, add 2 g of nano-calcium carbonate, ultrasonically process at 50 KHz for 1.5 h, filter, wash with deionized water 3 times, and dry in an oven at 80 °C for 10 min to obtain carbon fiber loaded with nano-calcium carbonate; B2. Add 3 g of carbon fiber loaded with nano-calcium carbonate to 8 g of ethylene glycol, stir at 175 °C for 5 h, add 17 g of terephthalic acid and 1.3 g of antimony trioxide, stir evenly, react at 240 °C and 0.6 MPa for 40 min, cool to room temperature, take out, wash with deionized water 3 times, and dry in an oven at 70 °C for 10 min to obtain modified nano-calcium carbonate.

[0064] Comparative Example 4 A preparation method of a fresh fruit and vegetable preservation packaging material combining a composite stone plastic box, a nuclear pore membrane and graphene technology, comprising the following preparation steps: S1. Mix polyethylene terephthalate, modified calcium carbonate and epoxy soybean oil, stir to form a mixed material, place the mixed material in a mold, and obtain a stone plastic box matrix through extrusion and shaping; among them, the mass ratio of polyester resin, modified calcium carbonate and epoxy soybean oil is 60:40:2; S2. Irradiate the PET polyester film with heavy ions to obtain a PET polyester nuclear pore membrane; among them, the heavy ion irradiation process: use the Lanzhou Heavy Ion Research Facility, a 129Xe ion beam with an energy of 80 MeV / u, and an irradiation fluence of 1×10 11 ions / cm 2 ; S3. Mix the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water and ethanol, and stir evenly to obtain a graphene antibacterial composite; wherein, the dosage ratio of the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water and ethanol is 3g:6g:55g:50mL:55mL; S4. Apply 12g of cyanoacrylate adhesive on the stone plastic box substrate, laminate the PET polyester nuclear pore membrane, after hot pressing, spray the graphene antibacterial composite, and after curing, obtain the fresh-keeping packaging material; wherein, the hot pressing process: the hot pressing temperature is 175°C, the hot pressing pressure is 15MPa, and the hot pressing time is 20min; the spraying pressure is 0.4MPa, the curing temperature is 120°C, and the curing time is 30min; The thickness of the stone plastic box substrate is 3mm; the thickness of the PET polyester film is 55μm; the thickness of the graphene antibacterial composite coating is 55μm.

[0065] The composite antibacterial material is specifically prepared by the following steps: A1. Add 2g of graphene oxide to 220mL of deionized water, stir evenly, add 3g of copper sulfate, perform ultrasonic mixing treatment at 50KHz for 30min, add 1.2g of L-ascorbic acid, react at 40°C for 2h, filter, wash with deionized water 3 times, and dry in an oven at 60°C for 12h to obtain graphene oxide loaded with nano copper; A2. Add 1.5g of naringin to 35mL of ethanol and 12mL of deionized water, stir evenly, add 0.6g of γ-aminopropyltriethoxysilane, stir and react at 80°C for 2h, add 2.9g of graphene oxide loaded with nano copper and 0.6mL of hydrochloric acid with a concentration of 0.1mol / L, continue to stir for 30min, filter, wash with deionized water 3 times, and dry in an oven at 60°C for 15min to obtain modified graphene oxide; A3. Add 3g of modified graphene oxide to 110mL of deionized water, stir evenly, add 1.3g of gum arabic and 0.6g of glycerol, perform ultrasonic treatment at 60KHz for 20min, and dry at 100°C until the water volatilizes to obtain the composite antibacterial material.

[0066] The modified calcium carbonate is specifically prepared by the following steps: B1. Add 6g of pretreated carbon fiber to 110mL of deionized water, stir evenly, add 2g of nano calcium carbonate, perform ultrasonic treatment at 50KHz for 1.5h, filter, wash with deionized water 3 times, and dry in an oven at 80°C for 10min to obtain carbon fiber loaded with nano calcium carbonate; Add 3 g of carbon fiber loaded with nano-calcium carbonate to 8 g of ethylene glycol, stir at 175 °C for 5 h, add 17 g of terephthalic acid and 1.3 g of antimony trioxide, stir evenly, react at 240 °C and 0.6 MPa for 40 min, cool to room temperature, take out, wash 3 times with deionized water, and dry in an oven at 70 °C for 10 min to obtain modified nano-calcium carbonate.

[0067] Comparative Example 5 A preparation method of a fresh fruit and vegetable fresh-keeping packaging material combining a composite stone plastic box, a nuclear pore membrane and graphene technology, comprising the following preparation steps: S1. Mix polyethylene terephthalate, modified calcium carbonate and epoxy soybean oil, stir to form a mixture, place the mixture in a mold, and obtain a stone plastic box matrix through extrusion and shaping; among them, the mass ratio of polyester resin, modified calcium carbonate and epoxy soybean oil is 60:40:2; S2. Irradiate the PET polyester film with heavy ions to obtain a PET polyester nuclear pore membrane; among them, the heavy ion irradiation process: use the Lanzhou Heavy Ion Research Facility, a 129Xe ion beam with an energy of 80 MeV / u, and an irradiation fluence of 1×10 11 ions / cm 2 ; S3. Mix the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water and ethanol, stir evenly to obtain a graphene antibacterial composite; among them, the dosage ratio of the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water and ethanol is 3 g:6 g:55 g:50 mL:55 mL; S4. Coat 12 g of cyanoacrylate adhesive on the stone plastic box matrix, laminate the PET polyester nuclear pore membrane, after hot pressing, spray the graphene antibacterial composite, and after curing, obtain the fresh-keeping packaging material; among them, the hot pressing process: the hot pressing temperature is 175 °C, the hot pressing pressure is 15 MPa, and the hot pressing time is 20 min; the spraying pressure is 0.4 MPa, the curing temperature is 120 °C, and the curing time is 30 min; The thickness of the stone plastic box matrix is 3 mm; the thickness of the PET polyester film is 55 μm; the thickness of the graphene antibacterial composite coating is 55 μm.

[0068] The composite antibacterial material is specifically prepared by the following steps: A1. Add 2 g of graphene oxide to 220 mL of deionized water, stir evenly, add 3 g of copper sulfate, ultrasonically mix and process at 50 KHz for 30 min, add 1.2 g of L-ascorbic acid, react at 40 °C for 2 h, filter, wash 3 times with deionized water, and dry in an oven at 60 °C for 12 h to obtain graphene oxide loaded with nano-copper; A2. Add 1.5 g of naringin to 35 mL of ethanol and 12 mL of deionized water, stir evenly, add 0.6 g of γ-aminopropyltriethoxysilane, stir and react at 80 °C for 2 h, add 2.9 g of graphene oxide loaded with nano-copper and 0.6 mL of hydrochloric acid with a concentration of 0.1 mol / L, continue to stir for 30 min, filter, wash with deionized water 3 times, and dry in an oven at 60 °C for 15 min to obtain modified graphene oxide; A3. Add 3 g of modified graphene oxide to 110 mL of deionized water, stir evenly, add 1.3 g of gum arabic and 0.6 g of glycerol, ultrasonically treat at 60 KHz for 20 min, and dry at 100 °C until the water evaporates to obtain a gum-modified graphene oxide composite material; A4. Add 9 g of sericin powder, 3 g of gum-modified graphene oxide composite material and 1.4 g of carboxymethyl cellulose to 55 mL of deionized water, stir and react at 50 °C for 50 min, place in a freezer, and freeze-dry at -20 °C for 20 h to obtain a composite antibacterial material.

[0069] The modified calcium carbonate is specifically prepared by the following steps: Add 3 g of nano-calcium carbonate to 8 g of ethylene glycol, stir at 175 °C for 5 h, add 17 g of terephthalic acid and 1.3 g of antimony trioxide, stir evenly, react at 240 °C and 0.6 MPa for 40 min, cool to room temperature, take out, wash with deionized water 3 times, and dry in an oven at 70 °C for 10 min to obtain modified nano-calcium carbonate.

[0070] Comparative Example 6 A preparation method of a fresh fruit and vegetable preservation packaging material with a composite stone plastic box-nuclear pore membrane-graphene technology includes the following preparation steps: S1. Mix polyethylene terephthalate, carbon fiber loaded with nano-calcium carbonate and epoxy soybean oil, stir to form a mixture, place the mixture in a mold, and obtain a stone plastic box matrix through extrusion and shaping; among them, the mass ratio of polyester resin, carbon fiber loaded with nano-calcium carbonate, and epoxy soybean oil is 60:40:2; S2. Irradiate the PET polyester film with heavy ions to obtain a PET polyester nuclear pore membrane; among them, the heavy ion irradiation process: use the Lanzhou Heavy Ion Research Facility, a 129Xe ion beam with an energy of 80 MeV / u, and an irradiation fluence of 1×10 11 ions / cm 2 ; S3. Mix the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water and ethanol, and stir evenly to obtain a graphene antibacterial composite; wherein, the dosage ratio of the composite antibacterial material, tetraethyl orthosilicate, polyethylene terephthalate, deionized water and ethanol is 3g:6g:55g:50mL:55mL; S4. Apply 12g of cyanoacrylate adhesive on the stone plastic box substrate, laminate the PET polyester nuclear pore membrane, after hot pressing, then spray the graphene antibacterial composite, and after curing, obtain the fresh-keeping packaging material; wherein, the hot pressing process: the hot pressing temperature is 175°C, the hot pressing pressure is 15MPa, and the hot pressing time is 20min; the spraying pressure is 0.4MPa, the curing temperature is 120°C, and the curing time is 30min; The thickness of the stone plastic box substrate is 3mm; the thickness of the PET polyester film is 55μm; the thickness of the graphene antibacterial composite coating is 55μm.

[0071] The composite antibacterial material is specifically prepared by the following steps: A1. Add 2g of graphene oxide to 220mL of deionized water, stir evenly, add 3g of copper sulfate, perform ultrasonic mixing treatment at 50KHz for 30min, add 1.2g of L-ascorbic acid, react at 40°C for 2h, filter, wash with deionized water 3 times, and dry in an oven at 60°C for 12h to obtain copper nanoparticle-loaded graphene oxide; A2. Add 1.5g of naringin to 35mL of ethanol and 12mL of deionized water, stir evenly, add 0.6g of γ-aminopropyltriethoxysilane, stir and react at 80°C for 2h, add 2.9g of copper nanoparticle-loaded graphene oxide and 0.6mL of hydrochloric acid with a concentration of 0.1mol / L, continue to stir for 30min, filter, wash with deionized water 3 times, and dry in an oven at 60°C for 15min to obtain modified graphene oxide; A3. Add 3g of modified graphene oxide to 110mL of deionized water, stir evenly, add 1.3g of gum arabic and 0.6g of glycerol, perform ultrasonic treatment at 60KHz for 20min, and dry at 100°C until the water evaporates to obtain a gum-modified graphene oxide composite material; A4. Add 9g of sericin powder, 3g of the gum-modified graphene oxide composite material and 1.4g of carboxymethyl cellulose to 55mL of deionized water, stir and react at 50°C for 50min, place in a freezer, and freeze-dry at -20°C for 20h to obtain the composite antibacterial material.

[0072] The carbon fiber loaded with nano calcium carbonate is specifically prepared by the following steps: 6 g of pretreated carbon fiber was added to 110 mL of deionized water, stirred evenly, 2 g of nano calcium carbonate was added, sonicated at 50 KHz for 1.5 h, filtered, washed 3 times with deionized water, and dried in an oven at 80 °C for 10 min to obtain carbon fiber loaded with nano calcium carbonate.

[0073] Now, the performance of the fresh-keeping packaging materials prepared in Examples 1-3 and Comparative Examples 1-6 was tested.

[0074] The prepared fresh-keeping packaging materials were cut into a style of 250 mm×250 mm×250 mm.

[0075] Compressive strength test: According to the ISTA 3A standard, it was tested with an ASTM D642 pressure testing machine.

[0076] Antibacterial performance detection: The antibacterial performance was detected according to the GB / T31402-2015 standard.

[0077] CO2 / O2 exchange ratio detection: The CO2 permeability and O2 permeability of the fresh-keeping packaging materials were measured according to the GB / T1038.1-2022 standard, the temperature was 25 °C, the relative humidity was 50%, and the CO2 / O2 exchange ratio = CO2 permeability / O2 permeability.

[0078] Fresh-keeping storage experiment: Intact blueberries (with a mass of m0) and lychees (with a mass of M0) were selected and respectively packed into the cut fresh-keeping packaging materials. The storage conditions for blueberries were: transportation distance of 1200 km, temperature of 0 °C, and humidity of 85%; the storage conditions for lychees were: transportation duration of 6 h and temperature of 30 °C. The weight loss rate of blueberries (%) = (m0 - m1) / m0, and the weight loss rate of lychees (%) = (M0 - M1) / M0, where m1 is the weight of blueberries measured after storage and M1 is the weight of lychees measured after storage.

[0079] The test results are shown in Table 1 below.

[0080] Table 1 Performance detection of the fresh-keeping packaging materials in Examples 1-3 and Comparative Examples 1-6

[0081] It can be seen from the data in Table 1 that the fresh-keeping packaging materials prepared in Examples 1-3 have good compressive strength and antibacterial performance, and have good fresh-keeping and storage performance for fruits and vegetables.

[0082] In Comparative Example 1, the graphene antibacterial composite prepared by replacing the graphene oxide loaded with nano copper with graphene oxide as the antibacterial layer of the fresh-keeping packaging material had a decline in antibacterial performance and fresh-keeping and storage performance, which proved that nano copper was formed on the surface of graphene oxide to avoid the agglomeration of nano copper, and graphene oxide and nano copper, as inorganic antibacterial materials, had good antibacterial activity.

[0083] In Comparative Example 2, the graphene antibacterial composite prepared by replacing the modified graphene oxide with graphene oxide loaded with nano-copper was used as the antibacterial layer of the fresh-keeping packaging material. The antibacterial performance and fresh-keeping storage performance decreased, which proved that the organic-inorganic antibacterial material was formed by coating the surface of the graphene oxide loaded with nano-copper with pomelo peel, enhancing the antibacterial activity of the fresh-keeping packaging material for fruits and vegetables. And naringin formed a flexible protective film on the surface of the graphene oxide loaded with nano-copper, protecting the antibacterial coating of the fresh-keeping packaging material.

[0084] In Comparative Example 3, the graphene antibacterial composite prepared by replacing the gum-modified graphene oxide composite with modified graphene oxide was used as the antibacterial layer of the fresh-keeping packaging material. The antibacterial performance, mechanical performance and fresh-keeping storage performance decreased, which proved that the polysaccharide segments of the gum were inserted between the modified graphene oxide nanosheets to form a layered structure with alternating organic and inorganic connections, which could reduce the water vapor transmission rate and improve the antibacterial activity. And the layered structure could absorb external stress and enhance the compressive strength of the fresh-keeping packaging material.

[0085] In Comparative Example 4, the graphene antibacterial composite prepared without adding sericin powder and carboxymethyl cellulose was used as the antibacterial layer of the fresh-keeping packaging material. The antibacterial performance, mechanical performance and fresh-keeping storage performance decreased, which proved that the gum-modified graphene oxide composite was dispersed in the sericin gel system, enhancing the adsorption and fixation of the modified graphene oxide, avoiding the easy migration and precipitation of the inorganic antibacterial material under external force, which affected the antibacterial activity. And the gum-modified graphene oxide increased the cross-linking density of the sericin gel, improving the mechanical strength of the sericin gel, and further enhancing the compressive strength of the fresh-keeping packaging material.

[0086] In Comparative Example 5, the modified calcium carbonate prepared by replacing the carbon fiber loaded with nano-calcium carbonate with nano-calcium carbonate was added to the stone plastic box matrix to form a fresh-keeping packaging material. The mechanical performance and fresh-keeping storage performance decreased, which proved that the nano-calcium carbonate was deposited on the surface of the pretreated carbon fiber to form a concave-convex structure, increasing the contact area with the stone plastic box matrix, and then better acting in the polyester stone plastic box. And the carbon fiber could form a transition layer that absorbed gravity in the stone plastic box matrix, enhancing the compressive strength of the fresh-keeping packaging material for fruits and vegetables.

[0087] In Comparative Example 6, the modified calcium carbonate prepared by replacing the modified nano-calcium carbonate with the carbon fiber loaded with nano-calcium carbonate was added to the stone plastic box matrix to form a fresh-keeping packaging material. The mechanical performance and fresh-keeping storage performance decreased, which proved that polyethylene terephthalate was formed on the surface of the carbon fiber loaded with nano-calcium carbonate, having excellent compatibility with the polyester stone plastic box, avoiding the agglomeration of calcium carbonate, which affected the compressive strength. And the modified calcium carbonate could form strong hydrogen bonds with the polyester stone plastic box matrix, making the modified calcium carbonate uniformly dispersed in the polyester stone plastic box matrix to form a cross-linked network structure, enhancing the compressive strength of the polyester stone plastic box.

[0088] In the description of the specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0089] The above content is only an illustration and explanation of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the described specific embodiments or use similar ways to substitute, as long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. A fresh fruit and vegetable fresh-keeping packaging material combining stone plastic box, nuclear pore membrane and graphene technologies, characterized in that, Prepared by the following method: S1. Mix polyester resin, modified calcium carbonate and plasticizer, stir to form a mixture, place the mixture in a mold, and obtain a stone plastic box substrate through extrusion and shaping; S2. Irradiate PET polyester film with heavy ions to obtain a PET polyester nuclear pore membrane; S3. Mix composite antibacterial material, tetraethyl orthosilicate, polyester resin, deionized water and ethanol, stir evenly to obtain a graphene antibacterial composite; S4. Coat an adhesive on the stone plastic box substrate, laminate the PET polyester nuclear pore membrane, after hot pressing, spray the graphene antibacterial composite, and after curing, obtain a fresh-keeping packaging material; The composite antibacterial material is obtained by mixing and reacting modified graphene oxide, gum, carboxymethyl cellulose and sericin powder; The modified graphene oxide is obtained by mixing and reacting copper sulfate pentahydrate, graphene oxide and L-ascorbic acid, and then reacting with naringin and a coupling agent; The modified calcium carbonate is obtained by depositing nano calcium carbonate on the surface of pretreated carbon fiber, and then mixing and reacting with ethylene glycol and terephthalic acid.

2. The fresh fruit and vegetable fresh-keeping packaging material of a composite stone plastic box-nuclear pore membrane-graphene technology according to claim 1, characterized in that, The composite antibacterial material is specifically prepared by the following steps: A1. Add graphene oxide to deionized water, stir evenly, add copper sulfate, after ultrasonic treatment, add L-ascorbic acid, react at 30-40 °C for 1-2 h, filter, wash, and dry to obtain graphene oxide loaded with nano copper; A2. Add naringin to ethanol and deionized water, stir evenly, add a coupling agent, stir and react at 70-80 °C for 1-2 h, add graphene oxide loaded with nano copper and hydrochloric acid, continue to stir for 20-30 min, filter, wash, and dry to obtain modified graphene oxide; A3. Add the modified graphene oxide to deionized water, stir evenly, add gum and glycerol, perform ultrasonic treatment at 40-60 KHz for 10-20 min, and dry until the water evaporates to obtain a gum-modified graphene oxide composite material; A4. Add sericin powder, gum-modified graphene oxide composite material and carboxymethyl cellulose to deionized water, stir and react at 45-50 °C for 40-50 min, and perform freeze-drying to obtain a composite antibacterial material.

3. The fresh fruit and vegetable fresh-keeping packaging material of a composite stone plastic box-nuclear pore membrane-graphene technology according to claim 2, characterized in that, In step A1, the dosage ratio of graphene oxide, deionized water, copper sulfate and L-ascorbic acid is (1-2) g: (180-220) mL: (2-3) g: (1-1.2) g.

4. The fresh fruit and vegetable fresh-keeping packaging material using a composite stone plastic box-nuclear pore membrane-graphene technology according to claim 2, wherein, In step A2, the dosage ratio of naringin, ethanol, deionized water, coupling agent, graphene oxide loaded with nano copper and hydrochloric acid is (1.3-1.5) g: (25-35) mL: (8-12) mL: (0.4-0.6) g: (2.5-2.9) g: (0.4-0.6) mL.

5. The fresh fruit and vegetable fresh-keeping packaging material of a composite stone plastic box-nuclear pore membrane-graphene technology according to claim 2, characterized in that, In step A3, the dosage ratio of modified graphene oxide, deionized water, gum and glycerol is (2-3) g: (90-110) mL: (1.1-1.3) g: (0.4-1.6) g.

6. The fresh fruit and vegetable fresh-keeping packaging material of a composite stone plastic box-nuclear pore membrane-graphene technology according to claim 2, characterized in that, In step A4, the dosage ratio of sericin powder, gum-modified graphene oxide composite material, carboxymethyl cellulose and deionized water is (8-9) g: (2-3) g: (1.2-1.4) g: (45-55) mL.

7. A fresh fruit and vegetable preservation packaging material using the composite stone plastic box - nuclear pore membrane - graphene technology according to claim 1, characterized in that, The modified calcium carbonate is specifically prepared by the following steps: B1. Add the pretreated carbon fiber into deionized water, stir evenly, add nano calcium carbonate, after ultrasonic treatment, filter, wash, and dry to obtain carbon fiber loaded with nano calcium carbonate; B2. Add the carbon fiber loaded with nano calcium carbonate into ethylene glycol, stir at 165 - 175 °C for 3 - 5 h, add terephthalic acid and antimony trioxide, stir evenly, react at 220 - 240 °C and 0.4 - 0.6 MPa for 30 - 40 min, cool to room temperature, take out, wash, and dry to obtain modified nano calcium carbonate.

8. A fresh fruit and vegetable fresh-keeping packaging material using a composite stone plastic box-nuclear pore membrane-graphene technology according to claim 7, characterized in that, In step B1, the dosage ratio of the pretreated carbon fiber, deionized water, and nano calcium carbonate is (5 - 6) g : (90 - 110) mL : (1 - 2) g.

9. The fresh fruit and vegetable fresh-keeping packaging material of a composite stone plastic box-nuclear pore membrane-graphene technology according to claim 7, characterized in that, In step B2, the mass ratio of the carbon fiber loaded with nano calcium carbonate, ethylene glycol, terephthalic acid, and antimony trioxide is (2 - 3) : (6 - 8) : (15 - 17) : (1.1 - 1.3).

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