A kind of shiitake mushroom EVA film packaging material and its production process

Abstract

The present invention relates to the technical field of EVA film packaging materials, and specifically discloses a shiitake mushroom EVA film packaging material and a production process thereof. The production process of the shiitake mushroom EVA film packaging material includes: dissolving tea polyphenols in an acetone solution, adding epichlorohydrin, stirring, adjusting the system pH value to 7-7.5, adding EVA, stirring in a constant temperature water bath, air drying, and obtaining modified EVA; adding a silane coupling agent to anhydrous ethanol, stirring, adding bamboo fiber, ultrasound, adjusting the system pH value to 7-7.5, stirring in a constant temperature water bath, filtering, air drying at room temperature, and obtaining activated bamboo fiber; adding modified EVA and activated bamboo fiber to a stirrer and stirring, hot pressing by a hot press, cooling, and obtaining shiitake mushroom EVA film packaging material. The shiitake mushroom EVA film packaging material of the present invention has high mechanical strength, good air permeability and antibacterial properties, and a simple preparation method, and is suitable for large-scale promotion and use.

Description

Technical Field

[0001] The invention relates to the technical field of EVA film packaging materials, in particular to a mushroom EVA film packaging material and a production process thereof. Background Art

[0002] As a new type of packaging material, EVA (ethylene-vinyl acetate copolymer) film occupies an important position in the field of food packaging due to its excellent transparency and good chemical stability. Especially in the preservation of agricultural products, EVA film is widely used in the packaging of fruits and vegetables, meat and aquatic products due to its excellent moisture-proof performance. Although EVA film has many advantages, in actual use, it still has certain limitations in terms of air permeability, antibacterial and mechanical strength as a packaging material for shiitake mushrooms.

[0003] First of all, shiitake mushrooms are a kind of edible fungus that is easy to decay and deteriorate, so an important factor affecting the preservation effect of shiitake mushrooms is the air permeability of the packaging material. However, the air permeability of traditional EVA films is relatively poor, which will cause excessive humidity on the surface of shiitake mushrooms, thereby causing the growth of bacteria and mold, and shortening the shelf life of shiitake mushrooms.

[0004] Secondly, the traditional EVA film itself does not have antibacterial properties, which makes shiitake mushrooms susceptible to microbial contamination during logistics and storage, thus affecting their food safety and quality.

[0005] Finally, in terms of mechanical strength, although the traditional EVA film itself has a certain toughness, its mechanical strength and impact resistance are relatively limited, which may also cause damage to the packaging material in a high-demand usage environment.

[0006] In the current prior art, patent CN106397961A proposes an antibacterial ultra-transparent EVA film and a preparation method thereof, which improves the antibacterial property of the EVA film by adding nano-silicon dioxide and silver-based inorganic antibacterial agents to the EVA film. The preparation method of this material is simple, does not require the addition of plasticizers, and has environmental protection characteristics. However, nanomaterials generally have poor dispersibility and are prone to "agglomeration", which not only affects the transparency of the film material, but also significantly reduces the mechanical strength of the film material and affects its toughness. Patent CN111718620B proposes a wear-resistant food-grade super-hydrophobic nano coating that does not stick to yogurt. This coating can be roller-coated on the EVA film and has good strength, wear resistance and heat sealing properties. However, although this coating can significantly enhance the mechanical strength of the EVA film, it does not have the characteristics of improving its air permeability and antibacterial properties. In actual use, poor air permeability will cause the internal humidity of the package to be too high, affecting the freshness of the food, and insufficient antibacterial properties will increase the risk of food deterioration.

[0007] In summary, although the existing technology has made certain progress in solving certain specific shortcomings of EVA film packaging materials, it is still impossible to simultaneously improve the antibacterial, breathable and mechanical strength properties of EVA films, which will seriously affect the application of EVA films in the packaging field and limit its market potential. Summary of the invention

[0008] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a method for preparing a high-toughness plastic film.

[0009] A production process of shiitake mushroom EVA film packaging material, comprising the following steps: S1. Weigh the raw materials by weight: 6-8 parts of EVA, 1.5-2.5 parts of tea polyphenols, 12-15 parts of acetone, 2-3 parts of epichlorohydrin, 15-20 parts of anhydrous ethanol, 1.5-2 parts of silane coupling agent, and 3-4 parts of bamboo fiber; S2, dissolving tea polyphenols in acetone solution, adding epichlorohydrin, stirring, adjusting the pH value of the system to 7-7.5, adding EVA, stirring in a constant temperature water bath, air drying, and obtaining modified EVA; S3, adding silane coupling agent to anhydrous ethanol, stirring, adding bamboo fiber, ultrasonic, adjusting the pH value of the system to 7-7.5, stirring in a constant temperature water bath, filtering, and air-drying to obtain activated bamboo fiber; S4, adding modified EVA and activated bamboo fiber into a blender and stirring, hot pressing through a hot press, cooling, and obtaining shiitake mushroom EVA film packaging material.

[0010] Preferably, the weight ratio of ethylene to vinyl acetate in EVA is 3:1.

[0011] Preferably, in step S2, epichlorohydrin is added at a rate of 2-3% per minute based on the total weight of the epichlorohydrin monomer.

[0012] Preferably, in step S2, epichlorohydrin is added, the stirring time is 1-2 hours, and the stirring speed is 300-500 r / min.

[0013] Preferably, in step S2, stirring is performed in a constant temperature water bath at 70-80° C. for 2-3 hours at a stirring speed of 200-300 r / min.

[0014] Preferably, in step S2, a sodium hydroxide solution with a concentration of 0.1-0.5 mol / L is used to adjust the pH value of the system to 7-7.5.

[0015] Preferably, in step S3, a silane coupling agent is added at a rate of 3-4% per minute based on the total weight of the silane coupling agent.

[0016] Preferably, in step S3, a silane coupling agent is added and stirred for 0.5-1 h at a stirring speed of 200-300 r / min.

[0017] Preferably, in step S3, the silane coupling agent is γ-aminopropyltriethoxysilane.

[0018] Preferably, in step S3, a sodium hydroxide solution with a concentration of 0.1-0.5 mol / L is used to adjust the pH value of the system to 7-7.5.

[0019] Preferably, in step S3, stirring is performed in a constant temperature water bath at 70-80° C. for 2-3 h at a stirring speed of 300-500 r / min.

[0020] Preferably, in the step S3, during the ultrasonic process, the ultrasonic treatment time is 0.5-1 h, and the ultrasonic frequency is 40-60 kHz.

[0021] Preferably, in step S4, during the stirring process of adding the mixture into the stirrer, the stirring time is 0.4-0.8h and the stirring speed is 400-500r / min.

[0022] Preferably, in step S4, hot pressing is performed by a hot press, the hot pressing time is 10-15 min, the hot pressing temperature is 140-150° C., and the hot pressing pressure is 0.4-0.5 MPa.

[0023] A shiitake mushroom EVA film packaging material, characterized in that it is made by adopting the production process of the shiitake mushroom EVA film packaging material according to any one of claims 1 to 9.

[0024] Beneficial effects: In the present invention, epichlorohydrin is added to graft epoxy groups onto tea polyphenol molecules, and the epoxy groups can not only react with the ester groups in EVA, but also integrate tea polyphenols into EVA, thereby giving EVA excellent antibacterial properties. At the same time, this process also generates active hydroxyl groups, which effectively improves the air permeability of the material, and multiple hydroxyl groups can interact with each other through hydrogen bonds to form a stable intermolecular network structure, thereby improving the mechanical strength of the material, and the generated ether bonds increase the attraction between molecules through dipole-dipole interactions and van der Waals forces, thereby further improving the mechanical strength of the material.

[0025] In the present invention, the alkoxy group at one end of the molecular structure of the silane coupling agent undergoes a hydrolysis condensation reaction with the hydroxyl group on the surface of the bamboo fiber to form a siloxane coating on the surface of the bamboo fiber. This process not only protects the bamboo fiber, but also introduces the amino functional group at the other end of the silane coupling agent to the surface of the bamboo fiber. Through hot pressing molding, while ensuring the air permeability and antibacterial properties of the bamboo fiber itself, the stability is extremely high, and the amino group bound to the surface of the bamboo fiber can form stable hydrogen bonds with the hydroxyl group and the remaining ester group in the modified EVA. These hydrogen bonds not only improve the bonding effect between the bamboo fiber and the modified EVA, but also enhance the cohesion of the material, so that the mechanical strength of the EVA film is further improved.

[0026] In the process of making EVA film packaging materials, the mechanical strength of the film can reflect the degree of bonding between EVA and other materials in the film. The higher the mechanical strength, the higher the degree of bonding, and the performance is improved accordingly. In the present invention, the air permeability and antibacterial properties of the EVA film packaging material are jointly improved through the mutual synergy of tea polyphenols and bamboo fiber and the close combination with the EVA film, while also strengthening the overall structure of the material, ensuring the freshness of the mushrooms and the durability of the packaging material to the greatest extent, and the preparation method is simple, low-cost, and suitable for large-scale promotion and production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a comparison chart of the air permeability coefficient tests of the shiitake mushroom EVA film packaging materials obtained in Example 5 and Comparative Examples 1-3.

[0028] Figure 2 This is a comparison chart of the antibacterial rate test of the shiitake mushroom EVA film packaging materials obtained in Example 5 and Comparative Examples 1-3.

[0029] Figure 3 This is a comparison chart of the elongation at break test of the shiitake mushroom EVA film packaging materials obtained in Example 5 and Comparative Examples 1-3.

[0030] Figure 4 This is a comparison chart of the tensile strength test of the shiitake mushroom EVA film packaging materials obtained in Example 5 and Comparative Examples 1-3. DETAILED DESCRIPTION

[0031] The present invention will be further explained below in conjunction with specific embodiments.

[0032] All the following EVAs were purchased from Taiwan Polymer Chemicals Co., Ltd., model UE653-04, with a VA content of 28% and a melt index of 400 MI, g / 10min.

[0033] Example 1 A production process of shiitake mushroom EVA film packaging material, comprising the following steps: S1. Weigh the raw materials: 60g EVA, 15g tea polyphenols, 120g acetone, 20g epichlorohydrin, 150g anhydrous ethanol, 15g γ-aminopropyltriethoxysilane, and 30g bamboo fiber; S2, dissolving tea polyphenols in acetone, adding epichlorohydrin, based on the total weight of epichlorohydrin monomer, the epichlorohydrin monomer addition rate is 2% per minute, stirring for 1 hour, the stirring speed is 300r / min, using a sodium hydroxide solution with a concentration of 0.1mol / L to adjust the system pH value to 7, adding EVA, stirring in a constant temperature water bath at 70°C for 2 hours, the stirring speed is 200r / min, and air-drying to obtain modified EVA; S3, add γ-aminopropyl triethoxysilane to anhydrous ethanol, based on the total weight of γ-aminopropyl triethoxysilane, add γ-aminopropyl triethoxysilane at a rate of 3% per minute, stir for 0.5h, the stirring speed is 200r / min, add bamboo fiber, ultrasonic treatment for 0.5h, the ultrasonic frequency is 40kHz, use a sodium hydroxide solution with a concentration of 0.1mol / L to adjust the system pH value to 7, stir in a constant temperature water bath at 70°C for 2h, the stirring speed is 300r / min, filter, air-dry, and obtain activated bamboo fiber; S4. Add modified EVA and activated bamboo fiber into a stirrer and stir for 0.4 h at a stirring speed of 400 r / min. Hot press for 10 min at a hot press temperature of 140° C. and a hot press pressure of 0.4 MPa. Cool and obtain shiitake mushroom EVA film packaging material.

[0034] Example 2 A production process of shiitake mushroom EVA film packaging material, comprising the following steps: S1. Weigh the raw materials: EVA 80g, tea polyphenols 25g, acetone 150g, epichlorohydrin 30g, anhydrous ethanol 200g, γ-aminopropyltriethoxysilane 20g, bamboo fiber 40g; S2, dissolving tea polyphenols in acetone, adding epichlorohydrin, based on the total weight of epichlorohydrin monomer, the epichlorohydrin monomer addition rate is 3% per minute, stirring for 2 hours, the stirring speed is 500r / min, using a sodium hydroxide solution with a concentration of 0.5mol / L to adjust the system pH value to 7.5, adding EVA, stirring in a constant temperature water bath at 80°C for 3 hours, the stirring speed is 300r / min, and air-drying to obtain modified EVA; S3, add γ-aminopropyltriethoxysilane to anhydrous ethanol, based on the total weight of γ-aminopropyltriethoxysilane, add γ-aminopropyltriethoxysilane at a rate of 4% per minute, stir for 1 hour, the stirring speed is 300r / min, add bamboo fiber, ultrasonic treatment for 1 hour, the ultrasonic frequency is 60kHz, use a sodium hydroxide solution with a concentration of 0.5mol / L to adjust the system pH value to 7.5, stir in a constant temperature water bath at 80°C for 3 hours, the stirring speed is 500r / min, filter, air-dry, and obtain activated bamboo fiber; S4. Add modified EVA and activated bamboo fiber into a stirrer and stir for 0.8 h at a stirring speed of 500 r / min. Use a hot press to hot press for 15 min at a temperature of 150° C. and a pressure of 0.5 MPa. Cool and obtain a shiitake mushroom EVA film packaging material.

[0035] Example 3 A production process of shiitake mushroom EVA film packaging material, comprising the following steps: S1. Weigh the raw materials: EVA 65g, tea polyphenols 17g, acetone 130g, epichlorohydrin 22g, anhydrous ethanol 160g, γ-aminopropyltriethoxysilane 16g, bamboo fiber 32g; S2, dissolving tea polyphenols in acetone, adding epichlorohydrin, based on the total weight of epichlorohydrin monomer, the epichlorohydrin monomer addition rate is 2.2% per minute, stirring for 1.2 hours, stirring speed is 350r / min, using 0.2mol / L sodium hydroxide solution to adjust the system pH value to 7.1, adding EVA, stirring in a constant temperature water bath at 72°C for 2.2 hours, stirring speed is 220r / min, air drying, and obtaining modified EVA; S3, add γ-aminopropyl triethoxysilane to anhydrous ethanol, based on the total weight of γ-aminopropyl triethoxysilane, the addition rate of γ-aminopropyl triethoxysilane is 3.2% per minute, stir for 0.6h, the stirring speed is 220r / min, add bamboo fiber, ultrasonic treatment for 0.6h, the ultrasonic frequency is 45kHz, the pH value of the system is adjusted to 7.1 with a sodium hydroxide solution with a concentration of 0.2mol / L, stir in a constant temperature water bath at 72°C for 2.2h, the stirring speed is 350r / min, filter, air-dry, and obtain activated bamboo fiber; S4. Add modified EVA and activated bamboo fiber into a stirrer and stir for 0.5 h at a stirring speed of 420 r / min. Use a hot press to hot press for 11 min at a hot pressing temperature of 142° C. and a hot pressing pressure of 0.42 MPa. Cool and obtain shiitake mushroom EVA film packaging material.

[0036] Example 4 A production process of shiitake mushroom EVA film packaging material, comprising the following steps: S1. Weigh the raw materials: EVA 75g, tea polyphenols 23g, acetone 140g, epichlorohydrin 28g, anhydrous ethanol 190g, γ-aminopropyl triethoxysilane 19g, bamboo fiber 38g; S2, dissolving tea polyphenols in acetone, adding epichlorohydrin, based on the total weight of epichlorohydrin monomer, the epichlorohydrin monomer addition rate is 2.8% per minute, stirring for 1.8 hours, stirring speed is 450r / min, using 0.4mol / L sodium hydroxide solution to adjust the system pH value to 7.4, adding EVA, stirring in a constant temperature water bath at 78°C for 2.8 hours, stirring speed is 280r / min, air drying, and obtaining modified EVA; S3, add γ-aminopropyl triethoxysilane to anhydrous ethanol, based on the total weight of γ-aminopropyl triethoxysilane, add γ-aminopropyl triethoxysilane at a rate of 3.8% per minute, stir for 0.9h, stir at a rate of 280r / min, add bamboo fiber, ultrasonically treat for 0.9h, the ultrasonic frequency is 55kHz, use a sodium hydroxide solution with a concentration of 0.4mol / L to adjust the system pH value to 7.4, stir in a constant temperature water bath at 78°C for 2.8h, stir at a rate of 450r / min, filter, and air-dry to obtain activated bamboo fiber; S4. Add modified EVA and activated bamboo fiber into a stirrer and stir for 0.7h at a stirring speed of 480r / min. Hot press for 14min at a hot press temperature of 148°C and a hot press pressure of 0.48MPa. Cool and obtain shiitake mushroom EVA film packaging material.

[0037] Example 5 A production process of shiitake mushroom EVA film packaging material, comprising the following steps: S1. Weigh the raw materials: EVA 70g, tea polyphenols 20g, acetone 135g, epichlorohydrin 25g, anhydrous ethanol 170g, γ-aminopropyltriethoxysilane 17g, bamboo fiber 35g; S2, dissolving tea polyphenols in acetone, adding epichlorohydrin, based on the total weight of epichlorohydrin monomer, the epichlorohydrin monomer addition rate is 2.5% per minute, stirring for 1.5 hours, the stirring speed is 400r / min, using a sodium hydroxide solution with a concentration of 0.3mol / L to adjust the system pH value to 7.2, adding EVA, stirring in a constant temperature water bath at 75°C for 2.5 hours, the stirring speed is 250r / min, and air-drying to obtain modified EVA; S3, add γ-aminopropyl triethoxysilane to anhydrous ethanol, based on the total weight of γ-aminopropyl triethoxysilane, add γ-aminopropyl triethoxysilane at a rate of 3.5% per minute, stir for 0.7h, stir at a rate of 250r / min, add bamboo fiber, ultrasonically treat for 0.7h, the ultrasonic frequency is 50kHz, use a sodium hydroxide solution with a concentration of 0.3mol / L to adjust the system pH value to 7.2, stir in a constant temperature water bath at 75°C for 2.5h, stir at a rate of 400r / min, filter, and air-dry to obtain activated bamboo fiber; S4. Add modified EVA and activated bamboo fiber into a stirrer and stir for 0.6 h at a stirring speed of 450 r / min. Hot press for 12 min at a hot press temperature of 145° C. and a hot press pressure of 0.45 MPa. Cool and obtain shiitake mushroom EVA film packaging material.

[0038] Comparative Example 1 A production process of shiitake mushroom EVA film packaging material, comprising the following steps: S1. Weigh the raw materials: EVA 70g, tea polyphenols 20g, bamboo fiber 35g; S2. Add EVA, tea polyphenols and bamboo fiber into a stirrer and stir for 0.6 h at a stirring speed of 450 r / min. Use a hot press to hot press for 12 min at a hot pressing temperature of 145° C. and a hot pressing pressure of 0.45 MPa. Cool and obtain shiitake mushroom EVA film packaging material.

[0039] Comparative Example 2 A production process of shiitake mushroom EVA film packaging material, comprising the following steps: S1. Weigh the raw materials: EVA 70g, tea polyphenols 20g, anhydrous ethanol 170g, γ-aminopropyl triethoxysilane 17g, bamboo fiber 35g; S2, add γ-aminopropyl triethoxysilane to anhydrous ethanol, based on the total weight of γ-aminopropyl triethoxysilane, the addition rate of γ-aminopropyl triethoxysilane is 3.5% per minute, stir for 0.7h, the stirring speed is 250r / min, add bamboo fiber, ultrasonic treatment for 0.7h, the ultrasonic frequency is 50kHz, the pH value of the system is adjusted to 7.2 with a sodium hydroxide solution having a concentration of 0.3mol / L, stir in a constant temperature water bath at 75°C for 2.5h, the stirring speed is 400r / min, filter, air-dry, and obtain activated bamboo fiber; S3. Add EVA, tea polyphenols and activated bamboo fiber into a stirrer and stir for 0.6 h at a stirring speed of 450 r / min. Use a hot press to hot press for 12 min at a temperature of 145° C. and a pressure of 0.45 MPa. Cool and obtain shiitake mushroom EVA film packaging material.

[0040] Comparative Example 3 A production process of shiitake mushroom EVA film packaging material, comprising the following steps: S1. Weigh the raw materials: EVA 70g, tea polyphenols 20g, acetone 135g, epichlorohydrin 25g, bamboo fiber 35g; S2, dissolving tea polyphenols in acetone, adding epichlorohydrin, based on the total weight of epichlorohydrin monomer, the epichlorohydrin monomer addition rate is 2.5% per minute, stirring for 1.5 hours, the stirring speed is 400r / min, using a sodium hydroxide solution with a concentration of 0.3mol / L to adjust the system pH value to 7.2, adding EVA, stirring in a constant temperature water bath at 75°C for 2.5 hours, the stirring speed is 250r / min, and air-drying to obtain modified EVA; S3. Add modified EVA and bamboo fiber into a stirrer and stir for 0.6 h at a stirring speed of 450 r / min. Use a hot press to hot press for 12 min at a hot pressing temperature of 145° C. and a hot pressing pressure of 0.45 MPa. Cool and obtain a shiitake mushroom EVA film packaging material.

[0041] Test Example 1 The air permeability coefficient of the mushroom EVA film packaging material obtained in Example 5 and Comparative Examples 1-3 was tested as follows: According to GB / T 1038 standard; three groups of circular specimens with a diameter of 50 mm were cut from the mushroom EVA film packaging materials of Example 5 and Comparative Examples 1-3, respectively, and recorded as Group 1, Group 2, and Group 3; the edges of the specimens were ensured to be neat without obvious defects and creases; the specimens were placed in the test cavity of a composite membrane differential pressure gas permeameter (produced by Jinan Saicheng Electronic Technology Co., Ltd., model SH103730), and a good seal was ensured between the specimen and the test cavity to avoid gas leakage; the test gas type was set to air, the test pressure difference was 100 Pa, the test temperature was 25°C, the test was started and reached a stable state, and the data was recorded.

[0042] The air permeability coefficient is calculated using the following formula , Where Q is the volume of gas that permeates the sample (cm³ / m²·s); A is the penetration area of ​​the sample (cm 2 ); ΔP is the pressure difference on both sides of the sample (Pa).

[0043] Depend on Figure 1It can be seen that the air permeability coefficients of the shiitake mushroom EVA film packaging materials prepared in Example 5 and Comparative Examples 1-3 are ranked as Example 5>Comparative Example 3>Comparative Example 2>Comparative Example 1, which shows that the shiitake mushroom EVA film packaging material prepared in Example 5 has the best air permeability. This is because the tea polyphenol molecules are grafted with epoxy groups by adding epichlorohydrin, and the epoxy groups can react with the ester groups of the vinyl acetate part in EVA, effectively improving the air permeability of the material, and the bamboo fiber itself has excellent air permeability. Although Comparative Example 3 also has hydroxyl groups and bamboo fibers, the mutual bonding degree between the materials is not as high as that in Example 5, so the air permeability is slightly reduced.

[0044] Test Example 2 The antibacterial rate of the shiitake mushroom EVA film packaging materials obtained in Example 5 and Comparative Examples 1-3 was tested as follows: Three groups of samples of the same size were cut from the shiitake mushroom EVA film packaging materials of Example 5 and Comparative Examples 1-3, respectively, and recorded as Group 1, Group 2, and Group 3; the samples were sterilized (by ultraviolet irradiation or ethylene oxide sterilization); under aseptic operation conditions, the Escherichia coli suspension was evenly coated on the surface of the sterilized culture medium plate, and then the samples were placed to ensure that the samples were in full contact with the culture medium, and blank control groups (i.e., culture medium plates inoculated with bacterial liquid without placing samples) were set up respectively; the plates were cultured at 37° C. for 24 hours, the colonies were counted, and the data were recorded.

[0045] Use the following formula to calculate: Antibacterial rate 100%, Among them, A is the number of colonies in the experimental group (the plate with the sample placed on it), and B is the number of colonies in the blank control group.

[0046] Both tea polyphenols and bamboo fiber have natural antibacterial properties, and the good combination between the materials can maximize this property in the EVA film packaging material for shiitake mushrooms. Figure 2It can be seen that the antibacterial rates of the shiitake mushroom EVA film packaging materials prepared in Example 5 and Comparative Examples 1-3 are ranked as Example 5>Comparative Example 3>Comparative Example 2>Comparative Example 1, indicating that the shiitake mushroom EVA film packaging material prepared in Example 5 has the best antibacterial performance. This is because the tea polyphenol molecules grafted with epoxy groups react with the ester groups of the vinyl acetate part in EVA to generate hydroxyl groups and ether bonds, which both have the function of improving the bonding degree between materials, so that the antibacterial performance of tea polyphenols can be well exerted; and the bamboo fiber is activated to form a siloxane coating on the surface of the bamboo fiber, and the amino functional groups on the surface of the activated bamboo fiber can form stable hydrogen bonds with the hydroxyl groups and ester groups in the modified EVA. These hydrogen bonds improve the bonding effect between the bamboo fiber and the modified EVA, and the antibacterial performance of the EVA film packaging material integrating tea polyphenols and bamboo fiber is well exerted, so the antibacterial effect of Example 5 is the best. In comparative example 3, no amino functional group was introduced on the surface of the bamboo fiber, and the remaining reactions were the same as those in example 5. Therefore, the antibacterial performance of comparative example 3 was inferior to that of example 5.

[0047] Test Example 3 The elongation at break and tensile strength of the shiitake mushroom EVA film packaging materials obtained in Example 5 and Comparative Examples 1-2 were tested as follows: According to GB / T 1040.1-2018 standard; 3 groups of samples of the same size were cut from the mushroom EVA film packaging materials of Example 5 and Comparative Examples 1-2, respectively, and recorded as Group 1, Group 2, and Group 3; ensure that the edges of the samples are flat and free of notches or cracks; use an electronic universal testing machine to clamp both ends of the sample in the upper and lower clamps of the testing machine to ensure that the sample is clamped and vertically, and will not cause the sample to break at the clamp, set the tensile speed of the testing machine to 50 mm / min, start the test, and the testing machine evenly stretches the sample until the sample breaks, and record the data.

[0048] Use the following formula to calculate: Elongation at break ) , Among them, L 断裂 is the length of the specimen when it breaks (mm), L 原始 is the original gauge length of the specimen (mm).

[0049] Use the following formula to calculate: Tensile strength Among them, F max is the maximum force when the specimen breaks (N), A 原始 is the original cross-sectional area of ​​the specimen (mm²).

[0050] Depend on Figure 3 , Figure 4It can be seen that the mechanical strength ranking of the shiitake mushroom EVA film packaging materials prepared in Example 5 and Comparative Examples 1-3 is Example 5> Comparative Example 3> Comparative Example 2> Comparative Example 1. This is because the tea polyphenol molecules grafted with epoxy groups react with the ester groups of the vinyl acetate part in EVA to generate hydroxyl groups and ether bonds, which both have the function of improving the bonding degree between materials. The bamboo fiber is activated to form a siloxane coating on the surface of the bamboo fiber, and the amino functional groups on the surface of the activated bamboo fiber form stable hydrogen bonds with the hydroxyl groups and ester groups in the modified EVA, which improves the bonding effect between the bamboo fiber and EVA and further enhances the cohesion of the material. Therefore, the mechanical strength of Example 5 is the best. In Comparative Example 3, no amino functional groups are introduced on the surface of the bamboo fiber, and the remaining reactions are the same as those in Example 5, so the mechanical strength of Comparative Example 3 is worse than that of Example 5.

[0051] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A production process for shiitake mushroom EVA film packaging material, characterized in that: The steps include: S1. Weigh the raw materials by weight: 6-8 parts of EVA, 1.5-2.5 parts of tea polyphenols, 12-15 parts of acetone, 2-3 parts of epichlorohydrin, 15-20 parts of anhydrous ethanol, 1.5-2 parts of silane coupling agent, and 3-4 parts of bamboo fiber; S2, dissolving tea polyphenols in acetone solution, adding epichlorohydrin, stirring, adjusting the pH value of the system to 7-7.5, adding EVA, stirring in a constant temperature water bath, air drying, and obtaining a modified EVA solution; S3, adding silane coupling agent to anhydrous ethanol, stirring, adding bamboo fiber, ultrasonic, adjusting the pH value of the system to 7-7.5, stirring in a constant temperature water bath, filtering, and air-drying to obtain activated bamboo fiber; S4, adding the modified EVA solution and the activated bamboo fiber into a stirrer, stirring, hot pressing by a hot press, cooling, and obtaining the mushroom EVA film packaging material.

2. The production process of the mushroom EVA film packaging material according to claim 1, characterized in that: In the step S2, epichlorohydrin is added, and the rate of adding the epichlorohydrin monomer is 2-3% per minute based on the total weight of the epichlorohydrin monomer.

3. The production process of the mushroom EVA film packaging material according to claim 1, characterized in that: In step S2, a sodium hydroxide solution with a concentration of 0.1-0.5 mol / L is used to adjust the pH value of the system to 7-7.

5.

4. The production process of the mushroom EVA film packaging material according to claim 1, characterized in that: In the step S3, a silane coupling agent is added, and the speed of adding the silane coupling agent is 3-4% per minute based on the total weight of the silane coupling agent.

5. The production process of the mushroom EVA film packaging material according to claim 1, characterized in that: In the step S3, during the ultrasonic process, the ultrasonic treatment time is 0.5-1h, and the ultrasonic frequency is 40-60kHz.

6. The production process of the mushroom EVA film packaging material according to claim 1, characterized in that: In the step S3, the silane coupling agent is γ-aminopropyltriethoxysilane.

7. The production process of the mushroom EVA film packaging material according to claim 1, characterized in that: In step S3, a sodium hydroxide solution with a concentration of 0.1-0.5 mol / L is used to adjust the pH value of the system to 7-7.

5.

8. The production process of the mushroom EVA film packaging material according to claim 1, characterized in that: In the step S4, during the stirring process of adding the mixture into the stirrer, the stirring time is 0.4-0.8h and the stirring speed is 400-500r / min.

9. The production process of the mushroom EVA film packaging material according to claim 1, characterized in that: In the step S4, hot pressing is performed by a hot press, the hot pressing time is 10-15 minutes, the hot pressing temperature is 140-150° C., and the hot pressing pressure is 0.4-0.5 MPa.

10. A mushroom EVA film packaging material, characterized in that: The packaging material is made by adopting the production process of the shiitake mushroom EVA film packaging material according to any one of claims 1 to 9.

Images