Shading moisture-proof container bag material and preparation method thereof

Abstract

The invention relates to a shading and moisture-proof container bag material and a preparation method thereof, and the shading and moisture-proof container bag material comprises a shading protective layer, a moisture-proof functional layer, a barrier strengthening layer and an inner contact layer, the barrier reinforced layer is prepared from the following raw materials in parts by mass: 30 to 40 parts of ethylene-vinyl alcohol copolymer, 20 to 30 parts of graft modified polyethylene, 10 to 15 parts of compatibilized nano boehmite, 3 to 8 parts of sulfonated modified SBS (Styrene Butadiene Styrene) and 0.5 to 1.5 parts of citric acid. The flexible freight bag material prepared by the invention has good shading performance, moisture resistance and tensile property, substances in the material have low migration rate, and the flexible freight bag material has good safety and reliability in application.

Description

Technical Field

[0001] This application relates to the technical field of flexible intermediate bulk containers, and particularly to a light-shielding and moisture-proof flexible intermediate bulk container material and a preparation method thereof. Background Art

[0002] With the increasing demand for large-scale storage and transportation of rice and flour products, light-shielding and moisture-proof flexible intermediate bulk containers face strict food contact safety requirements as key packaging carriers. Most existing materials adopt a multi-layer composite structure, and achieve functional characteristics by adding light-shielding masterbatch and moisture-proof coatings. However, in the actual application of long-term contact with food, it is found that some inorganic light-shielding fillers have the risk of heavy metal migration, while organic moisture-proof additives are prone to transfer low-molecular-weight substances to the food matrix.

[0003] The current technical bottleneck is mainly reflected in the interfacial compatibility contradiction between functional additives and food-grade substrates. It is difficult for traditional melt blending processes to achieve stable fixation of light-shielding components (such as titanium dioxide / carbon black) and moisture-proof components (such as nano-montmorillonite) in the polyolefin matrix. In the alternating temperature and humidity transportation environment, additive particles are likely to precipitate from the substrate surface to form free substances, which penetrate the inner food contact film through friction or electrostatic adsorption, causing foreign matter contamination of rice and flour products, so improvement is needed. Summary of the Invention

[0004] In order to improve the stability of light-shielding and moisture-proof flexible intermediate bulk containers, this application provides a light-shielding and moisture-proof flexible intermediate bulk container material and a preparation method thereof.

[0005] The light-shielding and moisture-proof flexible intermediate bulk container material and the preparation method provided by this application adopt the following technical solutions: In the first aspect, the light-shielding and moisture-proof flexible intermediate bulk container material provided by this application adopts the following technical solutions: A light-shielding and moisture-proof flexible intermediate bulk container material includes a light-shielding protective layer, a moisture-proof functional layer, a barrier strengthening layer, and an inner contact layer. The material of the inner contact layer is polypropylene. The preparation raw materials of the barrier strengthening layer include the following components in parts by mass: 30-40 parts of ethylene-vinyl alcohol copolymer 20-30 parts of graft-modified polyethylene 10-15 parts of compatibilized nano-boehmite 3-8 parts of sulfonated modified SBS 0.5-1.5 parts of citric acid.

[0006] The inner contact layer is made of polypropylene, which has chemical corrosion resistance, can ensure the safety of the contents, has good mechanical strength, and provides basic support for the whole; ethylene-vinyl alcohol copolymer has good gas barrier properties, can enhance the moisture-proof performance, its molecular chain is intertwined with other polymers, which is conducive to the improvement of tensile strength, and its own optical properties also improve the light-shielding performance; graft-modified polyethylene is grafted to introduce new functional groups, enhance the compatibility with each component to optimize the microstructure, and improve the stability and tensile strength; compatibilized nano-boehmite has nano-scale effect and high specific surface area, can enhance the tensile strength, adsorb small molecules to improve the moisture-proof property, and after compatibilization modification, it can be evenly dispersed, play the role of physical cross-linking points to enhance the stability, enhance the scattering of light, and improve the light-shielding performance; sulfonated modified SBS can improve the flexibility, reduce the occurrence of brittle fracture of the material, improve the tensile strength, its unique molecular structure can enhance the overall stability, synergistically optimize the microstructure with other components, and improve the moisture-proof and light-shielding properties; citric acid participates in the reaction during processing, regulates the process to promote the formation of a reasonable cross-linked structure between molecules, enhances the internal stability, comprehensively improves the tensile strength, moisture-proof property and light-shielding property, and improves the stability of the flexible intermediate bulk container material in a complex environment; through chemical bonding, physical entanglement and interaction among the components, a tight and orderly microstructure is formed, which restricts the molecular movement inside the material, reduces the diffusion channels of substances caused by intermolecular voids or defects, inhibits the migration of substances to the food contact surface, and makes the flexible intermediate bulk container material have good safety and reliability in food packaging applications.

[0007] Preferably, the raw materials for preparing the graft-modified polyethylene include polyethylene, hydroxyethyl acrylate and vinyltrimethoxysilane.

[0008] Polyethylene provides good flexibility and strength; hydroxyethyl acrylate contains a hydroxyl group and a double bond, and the double bond can undergo a graft reaction with the polyethylene molecular chain under the action of an initiator. The introduced hydroxyl group makes the material have a certain polarity, enhances the compatibility with other polar materials, improves the internal microstructure of the material, and improves the overall stability; at the same time, the introduction of this polarity helps to improve the adsorption capacity for small molecules and synergistically improve the moisture-proof performance; the siloxy group in vinyltrimethoxysilane can hydrolyze to form silanol groups, and then polycondense to form a silicone network, enhancing the heat resistance and tensile strength of the material; the double bond of the silane also participates in the graft reaction to further optimize the molecular structure, and the presence of the silicone network hinders the propagation of light, which can improve the light-shielding performance.

[0009] Preferably, the mass ratio of the polyethylene, hydroxyethyl acrylate and vinyltrimethoxysilane is 1:0.1:(0.25 - 0.35).

[0010] The graft-modified polyethylene prepared according to the above mass ratio has good light-shielding performance, moisture-proof performance and tensile performance.

[0011] Preferably, the raw materials for preparing the compatibilized nano-boehmite include nano-boehmite, silane coupling agent and graphene oxide.

[0012] Nano-boehmite has a large specific surface area and good thermal stability, providing a basic mechanical reinforcement for the material. Its crystal structure and nano-scale effect can enhance the scattering of light and reduce the light transmittance. One end of the silane coupling agent molecule can undergo a condensation reaction with the hydroxyl groups on the surface of nano-boehmite, and the organic functional group at the other end can interact with other organic polymers, thus building a bridge between nano-boehmite and other material components, improving the dispersibility and compatibility of nano-boehmite in the matrix, and enhancing the internal structural stability of the material. Graphene oxide has excellent mechanical properties, and its two-dimensional sheet structure can be evenly dispersed in the system. It synergizes with nano-boehmite to form physical cross-linking points inside the material, improving the tensile strength. The sheet structure of graphene oxide has a strong scattering and absorption effect on light, significantly enhancing the light-shielding performance. The hydrophobicity of graphene oxide and the adsorption of nano-boehmite work together synergistically to effectively prevent water vapor penetration and further improve the moisture-proof performance.

[0013] Preferably, the compatibilized nano-boehmite is prepared by the following steps: Disperse nano-boehmite and silane coupling agent in a solvent, heat and stir for reaction. After the reaction, centrifuge, wash and dry to obtain surface-modified boehmite. Mix graphene oxide and the above-prepared surface-modified boehmite and ball-mill to obtain the compatibilized nano-boehmite.

[0014] The compatibilized nano-boehmite prepared according to the above steps has good dispersibility and compatibility, and can effectively improve the moisture-proof performance, light-shielding performance and tensile strength of the container bag material.

[0015] Preferably, the raw materials for preparing the sulfonated modified SBS include SBS matrix, chlorosulfonic acid and hydrogenated rosin glyceride.

[0016] SBS has good flexibility and high elasticity. Chlorosulfonic acid, as a sulfonating agent, reacts with the SBS molecular chain to introduce sulfonic acid groups into the molecular structure, making SBS hydrophilic and ionic, improving the compatibility of SBS with other polar materials, promoting the interaction between various components inside the material, enhancing the overall stability, and also improving the moisture-proof performance to a certain extent because it can form hydrogen bonds with water molecules. The addition of hydrogenated rosin glyceride plays a dual role of plasticization and strengthening. Its long-chain structure inserts between the SBS molecular chains, improving the flexibility of the material, making the container bag easier to bend and not easily break during use, and further improving the tensile strength. At the same time, the conjugated double bond structure in hydrogenated rosin glyceride can absorb light of specific wavelengths, synergizing with other components with light-shielding properties to enhance the light-shielding effect of the container bag.

[0017] Preferably, the mass ratio of the SBS matrix, chlorosulfonic acid, and hydrogenated rosin glyceride is 1:0.12:(0.4 - 0.5).

[0018] The sulfonated modified SBS prepared according to the above mass ratio can effectively improve the light-shielding performance, moisture-proof performance, and tensile performance of the material.

[0019] Preferably, the light-shielding protective layer includes an aluminized polyester film.

[0020] The polyester film has good mechanical properties and chemical stability. The aluminizing process forms a thin and uniform aluminum layer on the film surface. Aluminum has excellent optical reflection characteristics and can efficiently reflect various lights such as visible light, ultraviolet light, and infrared light, thereby significantly reducing the light energy received by the food in the flexible intermediate bulk container, effectively preventing problems such as food oxidation, discoloration, and loss of nutritional components caused by light, and improving the light-shielding performance of the flexible intermediate bulk container. At the same time, the aluminum layer also has a certain barrier property and can block the penetration of some gases and water vapor, further improving the moisture-proof performance in cooperation with other layers.

[0021] Preferably, the moisture-proof functional layer includes a polyvinylidene chloride-coated polyester film.

[0022] The molecular structure of polyvinylidene chloride is compact and contains a large number of chlorine atoms. The high electronegativity of chlorine atoms makes the intermolecular force large and forms a highly dense molecular arrangement. This dense structure has a strong barrier ability to water molecules, making it difficult for water molecules to penetrate the polyvinylidene chloride coating, thereby effectively preventing external water vapor from entering the inside of the flexible intermediate bulk container and significantly improving the moisture-proof performance. At the same time, the polyvinylidene chloride coating has chemical stability and can resist the erosion of chemical substances in the environment, enhancing the durability and stability of the moisture-proof functional layer.

[0023] In a second aspect, the present application provides a method for preparing a light-shielding and moisture-proof flexible intermediate bulk container material, adopting the following technical solution: A method for preparing a light-shielding and moisture-proof flexible intermediate bulk container material includes the following steps: Stir and mix ethylene-vinyl alcohol copolymer, graft-modified polyethylene, compatibilized nano-boehmite, and sulfonated modified SBS to obtain a mixture; heat and melt the mixture, add citric acid in portions, stir and react, then extrude and air-cool to obtain a barrier reinforcement layer; Heat the hot-melt adhesive to melting, uniformly coat the molten hot-melt adhesive on the surfaces to be adhered of the two layers of materials to be laminated, apply pressure after lamination, and sequentially complete the lamination of the light-shielding protective layer, moisture-proof functional layer, barrier reinforcement layer, and inner contact layer to obtain a light-shielding and moisture-proof flexible intermediate bulk container material.

[0024] The light-shielding and moisture-proof flexible intermediate bulk container material prepared according to the above steps is safe and environmentally friendly. The material is closely cross-linked inside and has a stable microstructure, thereby reducing the migration rate of substances. Its good light-shielding and moisture-proof properties enable it to effectively protect the contents and meet the requirements of food storage and transportation.

[0025] In summary, the present application includes at least one of the following beneficial technical effects: 1. The inner contact layer uses polypropylene, which has chemical corrosion resistance, can ensure the safety of the contents, and has good mechanical strength, providing basic support for the whole. Ethylene-vinyl alcohol copolymer has good gas barrier properties, can enhance the moisture-proof performance. Its molecular chains are intertwined with other polymers, which is beneficial to the improvement of tensile strength, and its own optical properties also improve the light-shielding performance. Grafted modified polyethylene introduces new functional groups through grafting, enhances the compatibility with each component to optimize the microstructure, and improves stability and tensile strength. Compatibilized nano-boehmite has nano-scale effect and high specific surface area, can enhance the tensile strength, adsorb small molecules to improve the moisture-proof property, and after compatibilization modification, it can be evenly dispersed, acting as physical cross-linking points to enhance stability, enhance the scattering of light, and improve the light-shielding performance. Sulfonated modified SBS can improve flexibility, reduce the occurrence of brittle fracture of the material, improve the tensile strength, its unique molecular structure can enhance the overall stability, cooperate with other components to optimize the microstructure, and improve the moisture-proof and light-shielding properties. Citric acid participates in the reaction during processing, adjusts the process to promote the formation of a reasonable cross-linked structure between molecules, enhances the internal stability, comprehensively improves the tensile strength, moisture-proof property and light-shielding property, and improves the stability of the flexible intermediate bulk container material in a complex environment. The components form a tight and orderly microstructure through chemical bonding, physical entanglement and interaction, restrict the molecular movement inside the material, reduce the diffusion channels of substances caused by intermolecular voids or defects, inhibit the migration of substances to the food contact surface, and make the flexible intermediate bulk container material have good safety and reliability in food packaging applications.

[0026] 2. Polyethylene provides good flexibility and strength. Hydroxyethyl acrylate contains hydroxyl groups and double bonds. The double bonds can undergo grafting reactions with the polyethylene molecular chains under the action of initiators. The introduced hydroxyl groups make the material have a certain polarity, enhance the compatibility with other polar materials, improve the internal microstructure of the material, and improve the overall stability. At the same time, the introduction of this polarity helps to improve the adsorption capacity for small molecules and synergistically improve the moisture-proof property. The siloxy groups in vinyltrimethoxysilane can hydrolyze to form silanol groups, and then polycondense to form a silicone network, enhancing the heat resistance and tensile strength of the material. The double bonds of the silane also participate in the grafting reaction to further optimize the molecular structure, and the presence of the silicone network hinders the propagation of light, which can improve the light-shielding performance.

[0027] 3. SBS has good flexibility and high elasticity. As a sulfonating agent, chlorosulfonic acid reacts with the SBS molecular chain, introducing sulfonic acid groups into the molecular structure, making SBS hydrophilic and ionic, improving the compatibility of SBS with other polar materials, promoting the interaction between various components within the material, enhancing the overall stability, and also improving the moisture-proof performance to a certain extent because it can form hydrogen bonds with water molecules; the addition of hydrogenated rosin glyceride plays a dual role of plasticization and strengthening. Its long-chain structure inserts between the SBS molecular chains, improving the flexibility of the material, making the flexible intermediate bulk container easier to bend and less likely to break during use, and further enhancing the tensile strength; at the same time, the conjugated double bond structure in hydrogenated rosin glyceride can absorb light of specific wavelengths, collaborating with other components with light-shielding properties to enhance the light-shielding effect of the flexible intermediate bulk container. Detailed implementation mode

[0028] The embodiments of the present application disclose a light-shielding and moisture-proof flexible intermediate bulk container material and its preparation method. Except as otherwise specified, the raw materials used in the present application can be obtained through commercially available raw materials. The following further elaborates on the present application in combination with examples: Raw material description: Polyethylene (CAS No.: 9002-88-4), with a molecular weight of 200,000, 2-Hydroxyethyl acrylate (CAS No.: 818-61-1), Vinyltrimethoxysilane (CAS No.: 2768-02-7), Benzoyl peroxide (CAS No.: 94-36-0), Nanometer boehmite (CAS No.: 1318-23-6), with a particle size of 75 nm, the silane coupling agent model is KH550 (CAS No.: 919-30-2), Graphene oxide (CAS No.: 7782-42-5), purchased from Shanghai Kemi Chemical Technology Co., Ltd., SBS (CAS No.: 873-55-2), with a molecular weight of 100,000, Chlorosulfonic acid (CAS No.: 7790-94-5), Hydrogenated rosin glyceride (CAS No.: 65997-13-9), Ethylene-vinyl alcohol copolymer (CAS: 25067-34-9), with a molecular weight of 50,000, Citric acid (CAS No.: 77-92-9), the model of the hot-melt adhesive is Konor King 1108FDA-HA, the light-shielding protective layer material is aluminized polyester film, the moisture-proof functional layer material is polyvinylidene chloride-coated polyester film, and the inner contact layer is polypropylene.

[0029] Example 1 Preparation of graft-modified polyethylene Heat 37.04 g of polyethylene to 160 °C and stir at a speed of 400 rpm. After the polyethylene is completely melted, add 3.7 g of 2-Hydroxyethyl acrylate, 9.26 g of Vinyltrimethoxysilane, and 0.1 g of Benzoyl peroxide, and continue to stir and react at 160 °C at a speed of 400 rpm for 2 h. After the reaction is completed, cool to below 30 °C, granulate and discharge to obtain graft-modified polyethylene.

[0030] Preparation of compatibilized nano - boehmite Add 19.8 g of nano - boehmite and 0.6 g of silane coupling agent KH550 into 150 mL of absolute ethanol, ultrasonically disperse for 30 min, stir and react at 60 °C for 3 h. After the reaction, centrifuge, wash with deionized water, and dry at 60 °C to obtain surface - modified boehmite; Add 0.2 g of graphene oxide and the above - prepared surface - modified boehmite into a ball mill, and ball - mill at a speed of 300 rpm for 5 hours to obtain compatibilized nano - boehmite.

[0031] Preparation of sulfonated modified SBS Heat 6.58 g of SBS to 150 °C, stir at a speed of 200 rpm, dropwise add 0.79 g of chlorosulfonic acid, and finish dropping within 1 h. Stir and react at 150 °C and 200 rpm for 2 h, add 2.63 g of hydrogenated rosin glyceride, raise the temperature to 150 °C, stir and react at a speed of 300 rpm for 3 h. After the reaction, pour the product into sodium hydroxide solution for neutralization. After cooling to below 30 °C, filter, wash with deionized water, and dry at 60 °C to obtain sulfonated modified SBS.

[0032] Preparation of light - shielding and moisture - proof flexible intermediate bulk container material Mix 30 g of ethylene - vinyl alcohol copolymer, 20 g of graft - modified polyethylene, 10 g of compatibilized nano - boehmite and 3 g of sulfonated modified SBS, stir - mix at a speed of 1000 rpm for 15 min to obtain a mixed material; Add the mixed material into a twin - screw extruder, set the temperature of zone 1 to 150 °C, zone 2 to 170 °C, and zone 3 to 190 °C for heating and melting. When the screw speed is 200 rpm, start to add 0.5 g of citric acid in 3 times at intervals of 5 minutes in zone 2, stir and react for 20 min, then extrude through a die head and air - cool to 40 °C to obtain a barrier - strengthened layer with a thickness of 0.1 mm.

[0033] Heat the hot - melt adhesive to 180 °C to make it molten through a heating roller, and evenly coat the molten hot - melt adhesive on the surfaces to be adhered of the two materials to be laminated. Control the coating amount to 20 g / m 2 , after lamination, keep the pressure at 0.3 MPa for 10 s, and successively complete the lamination of the light - shielding protective layer, moisture - proof functional layer, barrier - strengthened layer and inner - layer contact layer to obtain the light - shielding and moisture - proof flexible intermediate bulk container material.

[0034] Example 2 Preparation of graft - modified polyethylene Heat 34.48 g of polyethylene to 160 °C and stir at a speed of 400 rpm. After the polyethylene is completely melted, add 3.45 g of hydroxyethyl acrylate, 12.07 g of vinyltrimethoxysilane and 0.1 g of benzoyl peroxide. Continue to stir and react at 160 °C and 400 rpm for 2 h. After the reaction is completed, cool to below 30 °C, granulate and discharge to obtain graft-modified polyethylene.

[0035] Prepare compatibilized nano-boehmite Add 19.8 g of nano-boehmite and 0.6 g of silane coupling agent KH550 to 150 mL of absolute ethanol, ultrasonically disperse for 30 min, stir and react at 60 °C for 3 h. After the reaction is completed, centrifuge, wash with deionized water, and dry at 60 °C to obtain surface-modified boehmite; Add 0.2 g of graphene oxide and the surface-modified boehmite prepared above to a ball mill and ball mill at a speed of 300 rpm for 5 hours to obtain compatibilized nano-boehmite.

[0036] Prepare sulfonated modified SBS Heat 6.17 g of SBS to 150 °C and stir at a speed of 200 rpm. Dropwise add 0.74 g of chlorosulfonic acid and finish dropping within 1 h. Stir and react at 150 °C and 200 rpm for 2 h. Add 3.09 g of hydrogenated rosin glyceride, raise the temperature to 150 °C, and stir and react at a speed of 300 rpm for 3 h. After the reaction is completed, pour the product into a sodium hydroxide solution for neutralization. After cooling to below 30 °C, filter, wash with deionized water, and dry at 60 °C to obtain sulfonated modified SBS.

[0037] Prepare light-shielding and moisture-proof flexible intermediate bulk container material Mix 40 g of ethylene-vinyl alcohol copolymer, 30 g of graft-modified polyethylene, 15 g of compatibilized nano-boehmite and 8 g of sulfonated modified SBS, and stir and mix at a speed of 1000 rpm for 15 min to obtain a mixed material; Add the mixed material to a twin-screw extruder, set the temperature of zone 1 to 150 °C, zone 2 to 170 °C, and zone 3 to 190 °C for heating and melting. When the screw speed is 200 rpm, start adding 1.5 g of citric acid in 3 portions at intervals of 5 minutes in zone 2. After stirring and reacting for 20 min, extrude through a die head and air-cool to 40 °C to obtain a barrier reinforcement layer with a thickness of 0.1 mm.

[0038] Heat the hot-melt adhesive to 180 °C through a heating roller to make it melt, and evenly coat the molten hot-melt adhesive on the bonding surfaces of the two materials to be bonded. Control the coating amount to 20 g / m 2 , and keep the pressure at 0.3 MPa for 10 s after lamination. Successively complete the lamination of the light-shielding protective layer, moisture-proof functional layer, barrier reinforcement layer and inner contact layer to obtain the light-shielding and moisture-proof flexible intermediate bulk container material.

[0039] Example 3 Preparation of graft-modified polyethylene Heat 35.71 g of polyethylene to 160 °C and stir at a speed of 400 rpm. After the polyethylene is completely melted, add 3.57 g of 2-hydroxyethyl acrylate, 10.72 g of vinyltrimethoxysilane and 0.1 g of benzoyl peroxide, and continue to stir and react at 160 °C at a speed of 400 rpm for 2 h. After the reaction is completed, cool to below 30 °C, granulate and discharge to obtain graft-modified polyethylene.

[0040] Preparation of compatibilized nano-boehmite Add 19.8 g of nano-boehmite and 0.6 g of silane coupling agent KH550 to 150 mL of absolute ethanol, ultrasonically disperse for 30 min, stir and react at 60 °C for 3 h. After the reaction is completed, centrifuge, wash with deionized water, and dry at 60 °C to obtain surface-modified boehmite; add 0.2 g of graphene oxide and the above-prepared surface-modified boehmite to a ball mill, and ball mill at a speed of 300 rpm for 5 hours to obtain compatibilized nano-boehmite.

[0041] Preparation of sulfonated modified SBS Heat 6.37 g of SBS to 150 °C and stir at a speed of 200 rpm. Dropwise add 0.76 g of chlorosulfonic acid and finish dropping within 1 h. Stir and react at 150 °C and 200 rpm for 2 h. Add 2.87 g of hydrogenated rosin glyceride, raise the temperature to 150 °C, and stir and react at a speed of 300 rpm for 3 h. After the reaction is completed, pour the product into a sodium hydroxide solution for neutralization. After cooling to below 30 °C, filter, wash with deionized water, and dry at 60 °C to obtain sulfonated modified SBS.

[0042] Preparation of light-shielding and moisture-proof bulk bag material Mix 35 g of ethylene-vinyl alcohol copolymer, 25 g of graft-modified polyethylene, 12.5 g of compatibilized nano-boehmite and 5.5 g of sulfonated modified SBS, and stir and mix at a speed of 1000 rpm for 15 min to obtain a mixed material; add the mixed material to a twin-screw extruder, set the temperature of the first zone to 150 °C, the second zone to 170 °C, and the third zone to 190 °C for heating and melting. When the screw speed is 200 rpm, start adding 1 g of citric acid in 3 times at intervals of 5 minutes in the second zone, stir and react for 20 min, then extrude through a die head and air-cool to 40 °C to obtain a barrier strengthening layer with a thickness of 0.1 mm.

[0043] Heat the hot-melt adhesive to 180 °C by a heating roller to make it melt, and evenly coat the molten hot-melt adhesive on the surfaces to be bonded of the two layers of materials to be laminated. The coating amount is controlled to be 20 g / m 2, after laminating, keep the pressure at 0.3 MPa for 10 s, and successively complete the lamination of the light-shielding protective layer, moisture-proof functional layer, barrier reinforcement layer and inner contact layer to obtain the light-shielding and moisture-proof flexible intermediate bulk container material.

[0044] Example 4 Example 4 is based on Example 3. The difference between Example 4 and Example 3 is only that the dosage of polyethylene in Example 4 is 40 g, the dosage of hydroxyethyl acrylate is 4 g, and the dosage of vinyltrimethoxysilane is 6 g.

[0045] Example 5 Example 5 is based on Example 3. The difference between Example 5 and Example 3 is only that the dosage of polyethylene in Example 5 is 32.26 g, the dosage of hydroxyethyl acrylate is 3.23 g, and the dosage of vinyltrimethoxysilane is 14.51 g.

[0046] Example 6 Example 6 is based on Example 3. The difference between Example 6 and Example 3 is only that hydroxyethyl acrylate is not added when preparing the graft-modified polyethylene in Example 6.

[0047] Example 7 Example 7 is based on Example 3. The difference between Example 7 and Example 3 is only that graphene oxide is not added when preparing the compatibilized nano-boehmite in Example 7.

[0048] Example 8 Example 8 is based on Example 3. The difference between Example 8 and Example 3 is only that the dosage of SBS in Example 8 is 7.04 g, the dosage of chlorosulfonic acid is 0.85 g, and the dosage of hydrogenated rosin glyceride is 2.11 g.

[0049] Example 9 Example 9 is based on Example 3. The difference between Example 9 and Example 3 is only that the dosage of SBS in Example 9 is 5.81 g, the dosage of chlorosulfonic acid is 0.7 g, and the dosage of hydrogenated rosin glyceride is 3.49 g.

[0050] Example 10 Example 10 is based on Example 3. The difference between Example 10 and Example 3 is only that chlorosulfonic acid is not added when preparing the sulfonated modified SBS in Example 10.

[0051] Comparative Example 1 Comparative Example 1 is based on Example 3. The difference between Comparative Example 1 and Example 3 is only that the graft-modified polyethylene is replaced with polyethylene in Comparative Example 1.

[0052] Comparative Example 2 Comparative Example 2 is based on Example 3. The only difference between Comparative Example 2 and Example 3 is that Comparative Example 2 replaces the compatibilized nano-boehmite with nano-boehmite.

[0053] Comparative Example 3 Comparative Example 3 is based on Example 3. The only difference between Comparative Example 3 and Example 3 is that Comparative Example 3 replaces the sulfonated modified SBS with SBS.

[0054] Performance detection test (1) Select "GB / T 10454-2000 Flexible Intermediate Bulk Containers" as the standard to test the tensile strength of the specimens. Prepare three samples for each specimen, and take the average value after measurement. The results are recorded in Table 1.

[0055] (2) Light-shielding property detection: Cut the specimen into samples of appropriate size, put them into the sample cell, use air as the reference, test and calculate the visible light transmittance. Each specimen is tested three times, and the average value is taken after measurement. The results are recorded in Table 1.

[0056] (3) Select "GB / T 1037-1988 Test Method for Water Vapor Transmission of Plastic Films and Sheets - Cup Method" as the standard. Seal the specimen on the moisture permeation cup, fill the cup with water, with the side of the specimen not in contact with food facing the water. Place the moisture permeation cup in an environment of 38 °C and 90% humidity for 24 h, weigh the weight change of the moisture permeation cup, calculate the water vapor transmission rate. Prepare three samples for each specimen, take the average value after measurement, and record the results in Table 1.

[0057] (4) Select "GB 31604.8-2021 National Food Safety Standard - Determination of Total Migration Amount of Food Contact Materials and Articles" as the standard. Cut the specimen into samples of 100 cm 2 . Select 10% ethanol as the food simulant, seal and soak for 10 d. After the soaking is completed, take out the specimen, rotary evaporate the soaking solution, transfer it to a glass petri dish and dry it to a constant weight, weigh the total mass of the petri dish and the residual substances after drying, and calculate the migration amount per unit area of the specimen. Prepare three samples for each specimen, take the average value after measurement, and record the results in Table 1.

[0058] Table 1 Detection results of tensile properties, light-shielding properties, moisture-proof properties and migration rate of flexible intermediate bulk container materials As can be seen from Table 1, the tensile strength of Examples 1-3 is greater than 38.72 MPa, the light transmittance is less than 0.6%, the water vapor transmission rate is less than 1.3 g / (m 2 ·d), and the migration amount is less than 0.95 mg / dm 2 . Thus, it can be seen that the flexible intermediate bulk container materials prepared in this application have good tensile strength, light-shielding properties, moisture-proof properties and low migration rate.

[0059] As can be seen from Table 1, the differences between Examples 4, 5, 6 and Example 3 are only as follows: in Example 4, the mass ratio of polyethylene, 2-hydroxyethyl acrylate and vinyltrimethoxysilane is 1:0.1:0.15; in Example 5, the mass ratio of polyethylene, 2-hydroxyethyl acrylate and vinyltrimethoxysilane is 1:0.1:0.45; in Example 6, 2-hydroxyethyl acrylate is not added when preparing the graft-modified polyethylene. Compared with Example 3, the performance of Examples 4, 5, and 6 has decreased; this is because after destroying the optimal component ratio, the synergistic effect between the components is affected; the lack of 2-hydroxyethyl acrylate further affects the synergistic effect between the components, the microstructure inside the material is affected, and the overall stability decreases.

[0060] As can be seen from Table 1, the difference between Example 7 and Example 3 is only that: graphene oxide is not added when preparing the compatibilized nano-boehmite in Example 7. Compared with Example 3, the performance of Example 7 has decreased. This is because the addition of graphene oxide is lacking, the synergistic effect between nano-boehmite and graphene oxide is missing, the strengthening effect is weakened, the dispersibility and compatibility of nano-boehmite decrease, and thus the performance of the flexible intermediate bulk container material is affected.

[0061] As can be seen from Table 1, the differences between Examples 8, 9, 10 and Example 3 are only as follows: in Example 8, the mass ratio of SBS, chlorosulfonic acid and hydrogenated rosin glyceride is 1:0.12:0.3; in Example 9, the mass ratio of SBS, chlorosulfonic acid and hydrogenated rosin glyceride is 1:0.12:0.6; in Example 10, chlorosulfonic acid is not added when preparing the sulfonated modified SBS. Compared with Example 3, the performance of Examples 8, 9, and 10 has decreased; this is because after destroying the optimal ratio, the synergistic effect between the components in the sulfonated modified SBS is affected; without adding chlorosulfonic acid, the compatibility between the components will decrease, moisture is more likely to penetrate, and the performance decreases.

[0062] As can be seen from Table 1, the difference between Comparative Example 1 and Example 3 is only that: in Comparative Example 1, the graft-modified polyethylene is replaced by polyethylene. Compared with Example 3, the performance of Comparative Example 1 has decreased significantly; this is because polyethylene lacks modification treatment, the compatibility between the components decreases, and interface defects are easily caused, resulting in significant decreases in tensile performance, moisture-proof performance and light-shielding performance.

[0063] As can be seen from Table 1, the difference between Comparative Example 2 and Example 3 is only that: in Comparative Example 2, the compatibilized nano-boehmite is replaced by nano-boehmite. Compared with Example 3, the performance of Comparative Example 2 has decreased significantly; this is because nano-boehmite lacks modification treatment, the dispersibility and compatibility decrease, and agglomeration is likely to occur, thus affecting the performance of the flexible intermediate bulk container material.

[0064] As can be seen from Table 1, the difference between Comparative Example 3 and Example 3 lies only in that: in Comparative Example 3, sulfonated modified SBS was replaced with SBS. Compared with Example 3, the performance of Comparative Example 3 decreased significantly; this is because SBS was not modified, the compatibility between components decreased, thus affecting the stability of the material, and the performance of the flexible intermediate bulk container material decreased significantly.

[0065] This specific embodiment is only an interpretation of the present application and does not limit the present application. Through the above description, relevant staff can make various changes and modifications completely within the scope without departing from the technical idea of this application. The technical scope of this application is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A light-shielding and moisture-proof flexible intermediate bulk container material, characterized in that: It includes a light-shielding protective layer, a moisture-proof functional layer, a barrier reinforcement layer, and an inner contact layer. The material of the inner contact layer is polypropylene. The preparation raw materials of the barrier reinforcement layer include the following components in parts by mass: 30 - 40 parts of ethylene-vinyl alcohol copolymer 20 - 30 parts of graft-modified polyethylene 10 - 15 parts of compatibilized nano-boehmite 3 - 8 parts of sulfonated modified SBS 0.5 - 1.5 parts of citric acid.

2. The light-shielding and moisture-proof flexible intermediate bulk container material according to claim 1, wherein: The preparation raw materials of the graft-modified polyethylene include polyethylene, 2-hydroxyethyl acrylate, and vinyltrimethoxysilane.

3. The light-shielding and moisture-proof flexible intermediate bulk container material according to claim 2, wherein: The mass ratio of the polyethylene, 2-hydroxyethyl acrylate, and vinyltrimethoxysilane is 1:0.1:(0.25 - 0.35).

4. The light-shielding and moisture-proof flexible intermediate bulk container material according to claim 1, wherein: The preparation raw materials of the compatibilized nano-boehmite include nano-boehmite, silane coupling agent, and graphene oxide.

5. The light-shielding and moisture-proof flexible intermediate bulk container material according to claim 4, wherein: The compatibilized nano-boehmite is prepared by the following steps: Disperse nano-boehmite and silane coupling agent into a solvent, heat and stir for reaction. After the reaction, centrifuge, wash, and dry to obtain surface-modified boehmite; mix graphene oxide and the above-prepared surface-modified boehmite and ball-mill to obtain compatibilized nano-boehmite.

6. The light-shielding and moisture-proof flexible intermediate bulk container material according to claim 1, wherein: The preparation raw materials of the sulfonated modified SBS include SBS matrix, chlorosulfonic acid, and hydrogenated rosin glyceride.

7. The light-shielding and moisture-proof flexible intermediate bulk container material according to claim 6, characterized in that: The mass ratio of the SBS matrix, chlorosulfonic acid, and hydrogenated rosin glyceride is 1:0.12:(0.4 - 0.5).

8. The light-shielding and moisture-proof flexible intermediate bulk container material according to claim 1, wherein: The light-shielding protective layer includes aluminized polyester film.

9. The light-shielding and moisture-proof flexible intermediate bulk container material according to claim 1, wherein: The moisture-proof functional layer includes polyvinylidene chloride-coated polyester film.

10. A preparation method for a light-shielding and moisture-proof flexible intermediate bulk container material as described in any one of claims 1-9, characterized in that: It includes the following steps: Stir and mix ethylene-vinyl alcohol copolymer, graft-modified polyethylene, compatibilized nano-boehmite, and sulfonated modified SBS to obtain a mixture; heat and melt the mixture, add citric acid in portions, stir and react, then extrude and air-cool to obtain the barrier reinforcement layer; Heat the hot-melt adhesive to melting, evenly coat the melted hot-melt adhesive on the surfaces to be bonded of the two materials to be laminated, apply pressure after lamination, and successively complete the lamination of the light-shielding protective layer, moisture-proof functional layer, barrier reinforcement layer, and inner contact layer to obtain the light-shielding and moisture-proof container bag material.

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