Preservative packaging film for inhibiting browning and method for preparing the same

Abstract

The application belongs to the technical field of agricultural product preservation, and particularly relates to a browning-inhibiting fresh-keeping packaging film and a preparation method thereof. The first layer to the fifth layer of the fresh-keeping packaging film from outside to inside comprises a first PE layer, a second PE layer, a third PA layer, a fourth PA layer and a fifth PE-EVA-POE layer in sequence; the first PE layer comprises the following raw materials in parts by weight: 25-40 parts of low-density polyethylene, 15-30 parts of linear low-density polyethylene, 30-60 parts of high-density polyethylene and 2-5 parts of modified nanomaterial; the modified nanomaterial is prepared by mixing nanometer titanium dioxide, nanometer silicon dioxide and nanometer zinc oxide, and then sequentially reacting with silane coupling agent KH570 and hyperbranched polymer. The fresh-keeping packaging film prepared by the application has excellent fruit browning prevention effect, strong puncture resistance and good low-temperature resistance.

Description

Technical Field

[0001] This invention belongs to the field of agricultural product preservation technology, specifically relating to a preservation packaging film that inhibits browning and its preparation method. Background Technology

[0002] Agricultural product preservation packaging film is a commonly used packaging material, typically used to extend the shelf life of fruits or other products. It protects the contents by blocking oxygen, moisture, light, and odors, and also has a heat-sealing function.

[0003] The purpose of using preservation packaging films for agricultural products is to effectively protect the integrity of agricultural products, extend their shelf life, and maintain their quality and appearance. However, the following problems still need to be addressed in the current technology: 1. Agricultural products (especially fruits and vegetables) are easily subjected to external pressure or collisions during transportation, storage, and sales, leading to packaging damage. If the packaging film does not have good puncture resistance, the agricultural products may be exposed to the external environment, accelerating spoilage. 2. Consumers usually have high requirements for the appearance of agricultural products; browning significantly reduces the product's appeal and affects sales. Reducing browning can slow down the aging process of fruits, keeping them fresh for a longer period. 3. Agricultural products contain a large amount of water. If the water vapor permeability of the packaging film is too high, it will lead to moisture loss, causing the product to wilt and dry out. Excessive water vapor permeability may also result in poor humidity inside the packaging, potentially promoting microbial growth and accelerating spoilage.

[0004] Chinese patent CN202411118536.3 discloses a low-temperature resistant, puncture-resistant antibacterial composite film and its application in food packaging. It employs a 7-layer co-extrusion blown film process, with materials including nylon, PE, and EVOH. PA is located on the outermost layer of the composite film; while puncture-resistant, PA is hygroscopic and its toughness deteriorates at low temperatures. The EVOH layer acts as a water vapor barrier, but EVOH is not resistant to low temperatures, becoming more brittle and less impact-resistant at low temperatures. The composite film prepared by this method has a relatively thin PA layer in the inner layer. Under low-temperature conditions, the thorns of vacuum-packed special fruits (such as lychees) can puncture the inner PA layer and the moisture-barrier EVOH layer, significantly reducing the barrier effect of the composite film. Furthermore, EVOH molecules contain hydroxyl groups, giving them strong hydrophilicity and hygroscopic properties. After EVOH absorbs moisture, its barrier properties decrease.

[0005] Therefore, there is an urgent need for a preservation packaging film that inhibits browning and its preparation method. Summary of the Invention

[0006] The purpose of this invention is to provide a preservation packaging film that inhibits browning and a method for preparing the same.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A preservation packaging film that inhibits browning, wherein the first to fifth layers of the preservation packaging film from the outside to the inside include: a first PE layer, a second PE layer, a third PA layer, a fourth PA layer and a fifth PE-EVA-POE layer;

[0009] The first PE layer comprises the following raw materials in parts by weight: 25-40 parts low-density polyethylene, 15-30 parts linear low-density polyethylene, 30-60 parts high-density polyethylene and 2-5 parts modified nanomaterials; the modified nanomaterials are prepared by mixing nano-titanium dioxide, nano-silica and nano-zinc oxide in a weight ratio of 1:(1.3-1.4):(0.5-0.7) and then reacting them sequentially with silane coupling agent KH570 and hyperbranched polymer.

[0010] Further, the preparation method of the hyperbranched polymer includes the following steps: mixing hydrolyzed polymaleic anhydride, diisopropanolamine, 3,5-diaminobenzoic acid, triethanolamine, and n-propyl titanate, and N,N-dimethylformamide, heating to 127-130℃, and reacting for 22-25 h to obtain the hyperbranched polymer; wherein the weight ratio of hydrolyzed polymaleic anhydride, 3,5-diaminobenzoic acid, diisopropanolamine, triethanolamine, n-propyl titanate, and N,N-dimethylformamide is 1:

[0011] (3-5): (1-2): (2-3): (0.2-0.3): (6-8).

[0012] This invention improves the puncture resistance of food preservation packaging films by adding modified nanomaterials to the first PE layer. A specific ratio of nano-titanium dioxide, nano-silica, and nano-zinc oxide, after modification, can achieve better compatibility with the components in the first PE layer, thereby improving puncture resistance.

[0013] Furthermore, the second PE layer comprises the following parts by weight of raw materials: 30-50 parts of low-density polyethylene, 20-40 parts of linear low-density polyethylene, and 10-50 parts of high-density polyethylene.

[0014] Furthermore, the raw materials used for the third PA layer and the fourth PA layer are both polyamide 6.

[0015] Furthermore, the fifth PE-EVA-POE layer comprises the following raw materials in parts by weight: 30-55 parts low-density polyethylene, 15-30 parts linear low-density polyethylene, 15-30 parts polyethylene-vinyl acetate, 10-15 parts polyolefin elastomer, and 4-7 parts anti-browning material.

[0016] Furthermore, the preparation method of the anti-browning material includes the following steps:

[0017] (1) Mix montmorillonite and diatomaceous earth in a weight ratio of 1:(1.2-1.5), stir evenly, place in deionized water, heat at 90-95℃ for 10-15 minutes, filter, and retain the filter residue; dry the filter residue until the water content is less than 8%, and then grind it to less than 800 mesh to obtain the adsorbent material.

[0018] (2) Prepare a tea polyphenol aqueous solution with a concentration of 5-8 g / L. Mix the adsorbent material with the tea polyphenol aqueous solution at a weight ratio of 1:(18-20), stir at a speed of 40-50 r / min for 4-5 h, centrifuge, and dry the precipitate obtained by centrifugation to obtain the anti-browning material.

[0019] This invention improves the anti-browning effect of food preservation packaging films by adding an anti-browning material to the fifth PE-EVA-POE layer. Furthermore, this invention utilizes montmorillonite and diatomaceous earth to load more tea polyphenols. Taking advantage of the antioxidant and enzyme-inhibiting properties of tea polyphenols, they are slowly released from the adsorbent material into the food environment. Montmorillonite and diatomaceous earth protect the tea polyphenols from external conditions, extending their active lifespan and improving the anti-browning effect. The simultaneous addition of modified nanomaterials and anti-browning materials in this invention reduces water vapor permeability.

[0020] Furthermore, the raw materials for the fifth PE-EVA-POE layer also include: 4-5 parts of slip agent and 6-8 parts of heat sealant.

[0021] Furthermore, the melt extrusion temperatures of the first to fifth layers are 195-210℃; 195-210℃; 230-240℃; 230-240℃; and 185-200℃, respectively.

[0022] Furthermore, the thicknesses of the first to fifth layers are 20-35μm, 20-30μm, 15-30μm, 15-30μm, and 30-40μm, respectively.

[0023] The present invention also provides a method for preparing the browning-inhibiting preservation packaging film, comprising the following steps: placing each layer of raw material into different extruders for melting and plasticizing, then co-extruding them at the die head, and blown into shape to obtain the packaging film.

[0024] The present invention also provides a preservation packaging film bag prepared from the aforementioned browning-inhibiting preservation packaging film.

[0025] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0026] 1. This invention breaks through the traditional formula in a 5-layer co-extrusion process. Instead of using only one PA layer in the middle or as the surface layer, existing technologies use PA in the third and fourth layers, increasing the flexibility and puncture resistance of the co-extruded film. The fifth layer uses three main raw materials, resulting in better tearability and low-temperature heat-sealing performance. The PA layer is designed inside to prevent moisture absorption, significantly improving overall freshness preservation performance. Tearability is also improved. Due to the double-layer PA design, the moisture barrier effect is significant, meaning water vapor permeability is significantly reduced.

[0027] 2. In this invention, fresh citrus or lychees are detwigged after harvest, individually vacuum-packed in bags, and stored in liquid nitrogen at -80°C for 30 days. After thawing in 0°C ice water for 30 minutes, the fruit maintains good freshness, and the puncture resistance of the packaging film is not significantly reduced. However, when using commercially available PE packaging bags as defined in this invention, after being placed under the same low-temperature conditions, the fruit shows obvious browning, the puncture resistance of the packaging film is significantly reduced, and the packaging film is not resistant to low temperatures.

[0028] When used at room temperature, this packaging film inhibits browning of the fruit peel compared to commercially available packaging. Through anti-browning effect testing, the total color difference (ΔE value) compared to fresh fruit peel does not exceed 10.

[0029] 3. By adding modified nanomaterials to the first PE layer, the present invention can improve the puncture resistance of the food preservation packaging film.

[0030] 4. By adding an anti-browning material to the fifth PE-EVA-POE layer, the present invention can improve the anti-browning effect of the food preservation packaging film.

[0031] 5. The present invention simultaneously adds modified nanomaterials and anti-browning materials, which can reduce water vapor transmission rate. Attached Figure Description

[0032] Figure 1 Images showing changes in fruit peel during an experiment to inhibit browning. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] All raw materials used in the following embodiments of the present invention are commercially available products:

[0035] Low-density polyethylene: CNOOC Shell Petrochemicals Co., Ltd., 2420T

[0036] Linear low-density polyethylene: ExxonMobil Chemical Company, LL1002BU

[0037] High-density polyethylene: ExxonMobil Chemical Company, H1003

[0038] Polyamide 6: CNOOC Shell Petrochemicals Co., Ltd. N6-011

[0039] Polyethylene-vinyl acetate: CNOOC Shell Petrochemicals Co., Ltd. 2409X

[0040] Polyolefin elastomer: Dow Chemical Company (China), POE5401

[0041] Nano titanium dioxide: particle size 10-20nm, specific surface area 30-100m2 / g; Beijing Deco Island Gold Technology Co., Ltd.

[0042] Nano-silica: average particle size 10nm, average specific surface area 380m² 2 / g, purchased from Jinlei Technology, model JL-S iO2-N10.

[0043] Nano zinc oxide: Particle size 30-50nm, specific surface area 15-30m² 2 / g; Zhejiang Zhitai Nano-Micro New Materials Co., Ltd.

[0044] Montmorillonite: Xianfeng Nano, model PGW.

[0045] Diatomite: Jilin Yuantong Mining Co., Ltd., model TL-301.

[0046] Hydrolyzed polymaleic anhydride: Shandong Haizhou Bioengineering Co., Ltd., molecular weight 400.

[0047] Example 1

[0048] A preservation packaging film that inhibits browning, wherein the first to fifth layers of the preservation packaging film from the outside to the inside include: a first PE layer, a second PE layer, a third PA layer, a fourth PA layer and a fifth PE-EVA-POE layer;

[0049] The first PE layer comprises the following parts by weight of raw materials: 30 parts low-density polyethylene, 20 parts linear low-density polyethylene, 40 parts high-density polyethylene and 3 parts modified nanomaterials.

[0050] The preparation method of the modified nanomaterial includes the following steps:

[0051] (1) Nano-titanium dioxide, nano-silica and nano-zinc oxide are mixed to obtain nanomaterials; wherein the weight ratio of nano-titanium dioxide, nano-silica and nano-zinc oxide is 1:1.3:0.6.

[0052] (2) The nanomaterial, silane coupling agent KH570 and 45% ethanol aqueous solution were mixed, the pH was adjusted to 4.5 with acetic acid, and the mixture was stirred at 47°C for 7 h. After filtration and drying, the pre-modified nanomaterial was obtained. The weight ratio of nanomaterial, silane coupling agent KH570 and 45% ethanol aqueous solution was 1:0.1:7.

[0053] (3) Hydrolyzed polymaleic anhydride, diisopropanolamine, 3,5-diaminobenzoic acid, triethanolamine, and n-propyl titanate, N,N-dimethylformamide were mixed and heated to 128°C and reacted for 23 h to obtain a hyperbranched polymer; the weight ratio of hydrolyzed polymaleic anhydride, 3,5-diaminobenzoic acid, diisopropanolamine, triethanolamine, n-propyl titanate, and N,N-dimethylformamide was 1:4:1.4:2.5:0.25:7;

[0054] (4) Under a nitrogen atmosphere, N,N-dimethylformamide, pre-modified nanomaterials, hyperbranched polymers and azobisisobutyronitrile were mixed and stirred for 25 min. The mixture was then reacted at 65 °C for 16 h. The weight ratio of N,N-dimethylformamide, pre-modified nanomaterials, hyperbranched polymers and azobisisobutyronitrile was 6:2.5:1:0.02. The mixture was filtered and dried to obtain modified nanomaterials.

[0055] The second PE layer comprises the following parts by weight of raw materials: 40 parts low-density polyethylene, 30 parts linear low-density polyethylene, and 25 parts high-density polyethylene.

[0056] The raw materials used for the third PA layer and the fourth PA layer are both polyamide 6.

[0057] The fifth PE-EVA-POE layer comprises the following raw materials in parts by weight: 42 parts low-density polyethylene, 23 parts linear low-density polyethylene, 27 parts polyethylene-vinyl acetate, 12 parts polyolefin elastomer, and 6 parts anti-browning material.

[0058] The preparation method of the anti-browning material includes the following steps:

[0059] (1) Mix montmorillonite and diatomaceous earth in a weight ratio of 1:1.4, stir evenly, place in deionized water, heat at 92°C for 12 minutes, filter, and retain the filter residue; dry the filter residue until the water content is less than 8%, and then grind it to less than 800 mesh to obtain the adsorbent material.

[0060] (2) Prepare a 6 g / L tea polyphenol aqueous solution, mix the adsorbent material with the tea polyphenol aqueous solution at a weight ratio of 1:19, stir at 45 r / min for 5 h, centrifuge, and dry the precipitate obtained by centrifugation to obtain the anti-browning material.

[0061] The method for preparing the browning-inhibiting preservation packaging film includes the following steps: Each layer of raw material is placed in a different extruder for melt plasticization, with the melt extrusion temperatures for the first to fifth layers being 200℃, 198℃, 233℃, 235℃, and 190℃ respectively; and then co-extruded at the die head, with the thicknesses of the first to fifth layers being 30μm, 25μm, 20μm, 18μm, and 34μm respectively. The film is then blown into shape with a blow-up ratio of 2.2:1 and a cooling water temperature of 25℃ to obtain the packaging film.

[0062] Example 2

[0063] A preservation packaging film that inhibits browning, wherein the first to fifth layers of the preservation packaging film from the outside to the inside include: a first PE layer, a second PE layer, a third PA layer, a fourth PA layer and a fifth PE-EVA-POE layer;

[0064] The first PE layer comprises the following parts by weight of raw materials: 28 parts of low-density polyethylene, 20 parts of linear low-density polyethylene, 35 parts of high-density polyethylene and 5 parts of modified nanomaterials.

[0065] The preparation method of the modified nanomaterial includes the following steps:

[0066] (1) Nano-titanium dioxide, nano-silica and nano-zinc oxide are mixed to obtain nanomaterials; wherein the weight ratio of nano-titanium dioxide, nano-silica and nano-zinc oxide is 1:1.3:0.7.

[0067] (2) The nanomaterial, silane coupling agent KH570 and 50% ethanol aqueous solution were mixed, the pH was adjusted to 4 with acetic acid, and the mixture was stirred at 50°C for 6 hours. After filtration and drying, the pre-modified nanomaterial was obtained. The weight ratio of nanomaterial, silane coupling agent KH570 and 50% ethanol aqueous solution was 1:0.1:7.

[0068] (3) Hydrolyzed polymaleic anhydride, diisopropanolamine, 3,5-diaminobenzoic acid, triethanolamine, and n-propyl titanate, N,N-dimethylformamide were mixed and heated to 127°C and reacted for 25 h to obtain a hyperbranched polymer; the weight ratio of hydrolyzed polymaleic anhydride, 3,5-diaminobenzoic acid, diisopropanolamine, triethanolamine, n-propyl titanate, and N,N-dimethylformamide was 1:3:1:2:0.3:8;

[0069] (4) Under a nitrogen atmosphere, N,N-dimethylformamide, pre-modified nanomaterials, hyperbranched polymers and azobisisobutyronitrile were mixed and stirred for 30 min. The mixture was then reacted at 70 °C for 15 h. The weight ratio of N,N-dimethylformamide, pre-modified nanomaterials, hyperbranched polymers and azobisisobutyronitrile was 5:2:1:0.03. The mixture was filtered and dried to obtain modified nanomaterials.

[0070] The second PE layer comprises the following parts by weight of raw materials: 42 parts low-density polyethylene, 36 parts linear low-density polyethylene, and 38 parts high-density polyethylene.

[0071] The raw materials used for the third PA layer and the fourth PA layer are both polyamide 6.

[0072] The fifth PE-EVA-POE layer comprises the following raw materials in parts by weight: 44 parts low-density polyethylene, 22 parts linear low-density polyethylene, 19 parts polyethylene-vinyl acetate, 15 parts polyolefin elastomer, and 7 parts anti-browning material.

[0073] The preparation method of the anti-browning material includes the following steps:

[0074] (1) Mix montmorillonite and diatomaceous earth in a weight ratio of 1:1.2, stir evenly, place in deionized water, heat at 95°C for 10 minutes, filter, and retain the filter residue; dry the filter residue until the water content is less than 8%, and then grind it to less than 800 mesh to obtain the adsorbent material.

[0075] (2) Prepare a tea polyphenol aqueous solution with a concentration of 5-8 g / L. Mix the adsorbent material with the tea polyphenol aqueous solution at a weight ratio of 1:20, stir at 50 r / min for 5 h, centrifuge, and dry the precipitate obtained by centrifugation to obtain the anti-browning material.

[0076] The method for preparing the browning-inhibiting preservation packaging film includes the following steps: Each layer of raw material is placed in a different extruder for melt plasticization, with the melt extrusion temperatures for the first to fifth layers being 200℃, 198℃, 233℃, 235℃, and 190℃ respectively; and then co-extruded at the die head, with the thicknesses of the first to fifth layers being 30μm, 25μm, 20μm, 18μm, and 34μm respectively. The film is then blown into shape with a blow-up ratio of 2.2:1 and a cooling water temperature of 25℃ to obtain the packaging film.

[0077] Comparative Example 1

[0078] The difference between this comparative example and Example 1 is that no modified nanomaterials are added to the first PE layer.

[0079] Comparative Example 2

[0080] The difference between this comparative example and Example 1 is that the weight ratio of nano-titanium dioxide, nano-silica, and nano-zinc oxide is 1:1:1.

[0081] Comparative Example 3

[0082] The difference between this comparative example and Example 1 is that the preparation method of the modified nanomaterial is different.

[0083] (1) Nano-titanium dioxide, nano-silica and nano-zinc oxide are mixed to obtain nanomaterials; wherein the weight ratio of nano-titanium dioxide, nano-silica and nano-zinc oxide is 1:1.3:0.6.

[0084] (2) The nanomaterial, silane coupling agent KH570 and 45% ethanol aqueous solution were mixed, the pH was adjusted to 4.5 with acetic acid, and the mixture was stirred at 47°C for 7 h. After filtration and drying, the modified nanomaterial was obtained. The weight ratio of nanomaterial, silane coupling agent KH570 and 45% ethanol aqueous solution was 1:0.1:7.

[0085] Comparative Example 4

[0086] The difference between this comparative example and Example 1 is that no anti-browning material is added to the fifth PE-EVA-POE layer.

[0087] Comparative Example 5

[0088] The difference between this comparative example and Example 1 is that it uses a commercially available product. Brand: Guangdong Huicheng Packaging Co., Ltd., five-layer co-extruded LDPE film, model PE-X, thickness 110μm * width 730mm.

[0089] Performance testing

[0090] 1. The heat-sealing strength of the packaging films of Example 1 and Comparative Example 5 was compared. The test conditions were 0.2 MPa and 1 s. The results are shown in Table 1.

[0091] Table 1. Heat seal strength test results (unit: N)

[0092] 115℃ 120℃ 125℃ 130℃ 135℃ 140℃ Example 1 0 4.5 20.6 23.2 24.5 26.5 Comparative Example 5 0 0 2.0 19.9 21.0 21.1

[0093] 2. The performance parameters of the packaging films of Examples 1-2 and Comparative Examples 1-5 were measured, and the results are shown in the figure.

[0094] Table 2.

[0095]

[0096]

[0097] As shown in Table 1, the food preservation packaging films of Examples 1-2 exhibit excellent overall performance. They possess good low-temperature heat-sealing properties, with a heat-sealing temperature of 120℃ that is 4.5N higher than commercially available products. Example 1 demonstrates a puncture resistance of 4.7N and an impact strength of 159kJ / m². 2 The nominal strain after stretching exceeds 460%.

[0098] In Comparative Example 1, without the addition of modified nanomaterials to the first PE layer, it can be seen that the puncture resistance, tensile strength, and impact strength of the food preservation packaging film are reduced.

[0099] In Comparative Example 2, the weight ratio of nano-titanium dioxide, nano-silica, and nano-zinc oxide was changed. The results show that the puncture resistance of the food preservation packaging film decreased and the water vapor permeability increased.

[0100] The preparation methods of the modified nanomaterials in Comparative Example 3 were different, and the results showed that the puncture resistance of the food preservation packaging film decreased.

[0101] In Comparative Example 4, the fifth PE-EVA-POE layer, without the addition of anti-browning materials, has a higher water vapor permeability.

[0102] Figure 1 These are images showing changes in the fruit peel during an experiment to inhibit browning. (Through...) Figure 1 It can be seen that the packaging film of Embodiment 1 of the present invention has a better anti-browning effect.

[0103] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A preservation packaging film that inhibits browning, characterized in that, The preservation packaging film, from the outside to the inside, comprises the following layers in sequence: a first PE layer, a second PE layer, a third PA layer, a fourth PA layer, and a fifth PE-EVA-POE layer; The first PE layer comprises the following raw materials in parts by weight: 25-40 parts low-density polyethylene, 15-30 parts linear low-density polyethylene, 30-60 parts high-density polyethylene and 2-5 parts modified nanomaterials; the modified nanomaterials are prepared by mixing nano-titanium dioxide, nano-silica and nano-zinc oxide, and then reacting them sequentially with silane coupling agent KH570 and hyperbranched polymer. The preparation method of hyperbranched polymer includes the following steps: hydrolyzed polymaleic anhydride, diisopropanolamine, 3,5-diaminobenzoic acid, triethanolamine, n-propyl titanate and N,N-dimethylformamide are mixed in a weight ratio of 1:(3-5):(1-2):(2-3):(0.2-0.3):(6-8), heated to 127-130℃, and reacted for 22-25 h to obtain hyperbranched polymer; The fifth PE-EVA-POE layer comprises the following raw materials in parts by weight: 30-55 parts low-density polyethylene, 15-30 parts linear low-density polyethylene, 15-30 parts polyethylene-vinyl acetate, 10-15 parts polyolefin elastomer, and 4-7 parts anti-browning material. The preparation method of anti-browning materials includes the following steps: (1) Mix montmorillonite and diatomaceous earth, stir evenly, place in deionized water, heat at 90-95℃ for 10-15 minutes, filter, and retain the filter residue; dry the filter residue, and then grind it to obtain the adsorbent material; (2) Prepare a tea polyphenol aqueous solution with a concentration of 5-8 g / L. Mix the adsorbent material with the tea polyphenol aqueous solution at a weight ratio of 1: (18-20), stir at a speed of 40-50 r / min for 4-5 h, centrifuge, and dry the precipitate obtained by centrifugation to obtain the anti-browning material.

2. The preservation packaging film for inhibiting browning according to claim 1, characterized in that, The second PE layer comprises the following parts by weight of raw materials: 30-50 parts low-density polyethylene, 20-40 parts linear low-density polyethylene, and 10-50 parts high-density polyethylene.

3. The preservation packaging film for inhibiting browning according to claim 1, characterized in that, The raw materials used for the third PA layer and the fourth PA layer are both polyamide 6.

4. The preservation packaging film for inhibiting browning according to claim 3, characterized in that, The raw materials for the fifth PE-EVA-POE layer also include: 4-5 parts of slip agent and 6-8 parts of heat sealant.

5. The preservation packaging film for inhibiting browning according to claim 1, characterized in that, The melt extrusion temperatures for the first to fifth layers are 195-210℃; 195-210℃; 230-240℃; 230-240℃; and 185-200℃, respectively.

6. A method for preparing a browning-inhibiting preservative packaging film according to any one of claims 1-5, characterized in that, The process includes the following steps: placing each layer of raw material into different extruders for melting and plasticizing, then co-extruding them at the die head, and blown into shape to obtain a packaging film.

7. A preservation packaging film bag prepared from the preservation packaging film for inhibiting browning as described in any one of claims 1-5.

Images