High-waterproofness photodegradable polyethylene film and preparation method thereof

Abstract

The high-waterproofness photodegradable polyethylene film is prepared from the following components in parts by mass: 70 to 85 parts of polyethylene, 1 to 3 parts of a photosensitizer, 2 to 5 parts of a waterproof reinforcing agent, 3 to 8 parts of a plasticizer, 5 to 10 parts of an auxiliary degradation agent and 0.5 to 1 part of an antioxidant, the preparation method of the high-waterproofness photodegradable polyethylene film comprises the following steps: drying the polyethylene master batch; carrying out dispersion treatment on the photosensitizer; adding the dried polyethylene, the plasticizer and the antioxidant into a high-speed mixer; carrying out melt blending through a twin-screw extruder to obtain premix particles; adding the premix particles, a photosensitizer, a waterproof reinforcing agent and an auxiliary degradation agent into a high-speed mixer; carrying out melt blending through a twin-screw extruder to obtain mixture particles; and then carrying out film blowing forming and surface treatment processes. The water resistance and controllable degradability of the film are remarkably improved, excellent mechanical properties are kept, the preparation process is simple, the cost is low, and the film is suitable for the fields of packaging, agricultural covering films and the like.

Description

Technical Field

[0001] The invention relates to the technical field of film preparation, and in particular to a highly waterproof photodegradable polyethylene film and a preparation method thereof. Background Art

[0002] Polyethylene (PE) is widely used in packaging, agricultural covering film, medical materials and other fields due to its excellent mechanical properties, chemical stability and low cost. However, traditional PE films have the following problems: non-degradability, PE is difficult to degrade in the natural environment, resulting in "white pollution", causing long-term damage to soil, water sources and ecosystems; insufficient waterproofness, ordinary PE films have limited waterproof performance, and are easy to absorb water in a humid environment, affecting their performance; single function, traditional films lack multifunctionality and are difficult to meet the needs of high-end application fields. In order to solve the environmental problems of traditional plastic films, photodegradable films came into being; photodegradable films achieve degradation by adding photosensitizers to polymers and using light to induce polymer chain breakage; however, existing photodegradable films have the following technical bottlenecks: uncontrollable degradation rate, the degradation rate of photodegradable films is affected by factors such as light intensity and ambient temperature, and is difficult to accurately control, which may lead to premature degradation or incomplete degradation; poor waterproofness, after adding photosensitizers, photodegradable films often sacrifice waterproof performance, limiting their application in humid environments; mechanical properties decline, the addition of photosensitizers may cause the mechanical properties of the film to decline, affecting its service life.

[0003] With the enhancement of environmental awareness and the promotion of policies, the market demand for biodegradable materials is growing. At the same time, high-end application fields have put forward higher requirements for the functionality of films.

[0004] Therefore, the present invention provides a highly waterproof photodegradable polyethylene film and a preparation method thereof, and developing a photodegradable film with high waterproofness, controllable degradation and good mechanical properties has important practical significance. Summary of the invention

[0005] The purpose of the present invention is to provide a highly waterproof photodegradable polyethylene film and a preparation method thereof, so as to solve the problems of poor waterproofness and uncontrollable degradation rate of the photodegradable film in the prior art.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A highly waterproof photodegradable polyethylene film comprises, by weight, 70-85 parts of polyethylene (PE), 1-3 parts of photosensitizer, 2-5 parts of waterproof enhancer, 3-8 parts of plasticizer, 5-10 parts of auxiliary degradation agent and 0.5-1 part of antioxidant.

[0008] Preferably, the photosensitizer is selected from one of ferric acetylacetonate, ferrocene, ammonium ferric oxalate, cobalt acetylacetonate, cobalt chloride, cobalt oxalate, manganese acetylacetonate, nickel acetylacetonate, and copper acetylacetonate.

[0009] Preferably, the waterproof enhancer is modified nano-silica, and the modified nano-silica is selected from one or more of aminosilane-modified nano-silica, epoxysilane-modified nano-silica, methacryloxysilane-modified nano-silica, hexadecyltrimethoxysilane-modified nano-silica, perfluorooctyltriethoxysilane-modified nano-silica, polymethyl methacrylate-grafted nano-silica, and polystyrene-grafted nano-silica.

[0010] Preferably, the plasticizer is selected from one of epoxidized soybean oil (ESO), epoxidized linseed oil (ELO), triethyl citrate (TEC), tributyl citrate (TBC), acetyl tributyl citrate (ATBC), acetylated monoglyceride, and epoxy fatty acid methyl ester (EFAME).

[0011] Preferably, the auxiliary degradation agent is selected from one of microcrystalline cellulose (MCC), carboxymethyl cellulose (CMC), starch, polylactic acid (PLA), chitosan, soy protein, zein, polycaprolactone (PCL), polyhydroxyalkanoate (PHA), polybutylene succinate (PBS), ferric acetylacetonate, and cobalt acetylacetonate.

[0012] Preferably, the antioxidant is selected from one of 2,6-di-tert-butyl-p-cresol (BHT), 1010 antioxidant, 1076 antioxidant, triphenyl phosphate (TPP), 168 antioxidant, tris(nonylphenyl) phosphite (TNPP), and vitamin E.

[0013] The present application also claims a method for preparing the above-mentioned highly waterproof photodegradable polyethylene film, comprising the following steps:

[0014] (1) Drying of polyethylene masterbatch: Dry the polyethylene in an oven at 80°C to 100°C for 4 to 6 hours to remove moisture and avoid bubbles during processing. After drying, cool the masterbatch to room temperature for later use;

[0015] (2) Dispersion treatment of photosensitizer: Mix the photosensitizer with ethanol and perform ultrasonic dispersion for 30 to 35 minutes to ensure that the photosensitizer is evenly dispersed; dry the dispersion at 60 to 63° C. to remove the ethanol and obtain a powdered photosensitizer for later use;

[0016] (3) Preparation of premix: adding the dried polyethylene, plasticizer and antioxidant into a high-speed mixer; mixing at 60° C. to 80° C. for 10 to 15 minutes to ensure uniform dispersion of the components; melt blending the premix through a twin-screw extruder at a temperature of 160° C. to 200° C. to obtain premix particles;

[0017] (4) Preparation of a mixture: adding premix particles, photosensitizer, waterproof enhancer, and auxiliary degradation agent to a high-speed mixer; mixing at 80° C. to 100° C. for 15 to 20 minutes to ensure uniform dispersion of the components; melt blending the mixture through a twin-screw extruder at a temperature of 180° C. to 220° C. to obtain mixture particles;

[0018] (5) Film blowing: Add the mixed material particles into the hopper of the film blowing machine, control the film blowing temperature, adjust the stretch ratio and inflation ratio of the film blowing machine, and blow the mixed material into a film through the film blowing machine. The film thickness is controlled at 20 to 50 μm.

[0019] (6) Plasma treatment: The film is passed through a plasma treatment device with a treatment power of 100 to 200 W and a treatment time of 1 to 3 minutes. Plasma treatment can improve the polarity and water resistance of the film surface.

[0020] (7) Fluorination treatment: immerse the film in a fluorination treatment solution for 10 to 15 minutes, take out the film, and dry it at 80 to 85°C for 1 to 2 hours to allow the fluorination agent to firmly adhere to the surface of the film;

[0021] (8) Cooling and winding:

[0022] The treated film is cooled to room temperature by a cooling roller, and the film is rolled up using a winder, and the winding tension is controlled at 5 to 10N to avoid deformation of the film.

[0023] Preferably, in step (5), the barrel temperature for controlling the film blowing temperature is 190°C to 210°C; the die head temperature is 200°C to 220°C, the stretch ratio of the film blowing machine is adjusted to 2 to 4:1, and the inflation ratio is 2 to 3:1.

[0024] Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0025] 1. The highly waterproof photodegradable polyethylene film of the present invention has high waterproofness. By adding modified nano-silicon dioxide and combining surface treatment technology, the waterproof performance of the film is significantly improved; the water contact angle is ≥115°, and the water vapor permeability is ≤5g / m 2 24h, suitable for applications in humid environments;

[0026] 2. The present invention realizes the controllable photodegradation of the film by adding photosensitizer and auxiliary degradation agent. Under natural light, the degradation rate is ≥60% within 90 days, which solves the environmental problem that traditional plastic films are difficult to degrade. It can be degraded in the natural environment, reducing "white pollution". The degradation products are harmless to the environment and meet environmental protection requirements.

[0027] 3. The highly waterproof photodegradable polyethylene film of the present invention has excellent mechanical properties. By optimizing the formula and process, the tensile strength of the film is ≥20MPa and the elongation at break is ≥300%, which meets the needs of various application scenarios;

[0028] 4. The preparation process of the highly waterproof photodegradable polyethylene film of the present invention has low energy consumption and does not produce harmful gases during the degradation process, which helps to reduce carbon emissions;

[0029] 5. The preparation process of the highly waterproof photodegradable polyethylene film of the present invention is simple, easy to industrialize, and has a wide range of applications. It can be used for food packaging, electronic product packaging, etc., provides high waterproofness and environmental protection, is suitable for agricultural covering film, increases crop yields, and reduces farmland plastic pollution. It is suitable for medical packaging materials and has both waterproofness and biocompatibility. DETAILED DESCRIPTION

[0030] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, a specific implementation scheme is now described in detail.

[0031] The present invention is further described below in conjunction with the examples, but the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the different requirements of specific use, and the implementation conditions not indicated are conventional conditions in the industry. The technical features involved in each embodiment of the present invention can be combined with each other as long as they do not conflict with each other.

[0032] Example 1

[0033] This embodiment provides a highly waterproof photodegradable polyethylene film, which includes, by weight, 80 parts of polyethylene (PE), 2 parts of photosensitizer ferric acetylacetonate, 3 parts of waterproof enhancer aminosilane-modified nano-silica, 5 parts of plasticizer epoxy soybean oil, 5 parts of auxiliary degradation agent polycaprolactone, and 0.5 parts of 1010 antioxidant;

[0034] The method for preparing the above-mentioned highly waterproof photodegradable polyethylene film comprises the following steps:

[0035] (1) Drying of polyethylene masterbatch: Dry the polyethylene in an oven at 90°C for 5 hours to remove moisture and avoid bubbles during processing. After drying, cool the masterbatch to room temperature for later use;

[0036] (2) Dispersion treatment of photosensitizer: Mix ferric acetylacetonate and ethanol, and disperse by ultrasonic for 35 minutes to ensure that the photosensitizer is evenly dispersed; dry the dispersion at 60° C. to remove the ethanol, and obtain a powdered photosensitizer for later use;

[0037] (3) Preparation of premix: Add the dried polyethylene, epoxidized soybean oil and 1010 antioxidant into a high-speed mixer; mix at 75° C. for 15 minutes to ensure that the components are evenly dispersed; melt-blend the premix through a twin-screw extruder at a temperature of 180° C. to obtain premix particles;

[0038] (4) Preparation of a mixture: adding the premix particles and the dispersed ferric acetylacetonate, aminosilane-modified nano-silica, and polycaprolactone to a high-speed mixer; mixing at 85° C. for 20 minutes to ensure that the components are evenly dispersed; and melt-blending the mixture through a twin-screw extruder at a temperature of 210° C. to obtain mixture particles;

[0039] (5) Film blowing: Add the mixed material particles into the hopper of the film blowing machine, control the barrel temperature of the film blowing temperature to 200°C; the die temperature is 220°C, adjust the stretch ratio of the film blowing machine to 3:1 and the blowing ratio to 2:1, and blow the mixed material into a film through the film blowing machine, and the film thickness is controlled at 30-40 μm;

[0040] (6) Plasma treatment: The film is passed through a plasma treatment device with a treatment power of 180 W and a treatment time of 2 minutes. Plasma treatment can improve the polarity and water resistance of the film surface;

[0041] (7) Fluorination treatment: The film was immersed in a fluorination treatment solution (ethanol solution of perfluorooctyltriethoxysilane) for 12 minutes, the film was taken out, and dried at 80°C for 1.5 hours to make the fluorination agent firmly adhere to the surface of the film;

[0042] (8) Cooling and winding:

[0043] The treated film was cooled to room temperature by a cooling roller, and the film was wound up using a winder with the winding tension controlled at 8N to avoid deformation of the film.

[0044] Example 2

[0045] This embodiment provides a highly water-resistant photodegradable polyethylene film, which includes, by weight, 80 parts of polyethylene (PE), 2 parts of photosensitizer cobalt acetylacetonate, 3 parts of water-resistant enhancer epoxysilane-modified nano-silica, 5 parts of plasticizer triethyl citrate, 5 parts of auxiliary degradation agent polycaprolactone, and 0.5 parts of 1010 antioxidant;

[0046] The method for preparing the above-mentioned highly waterproof photodegradable polyethylene film comprises the following steps:

[0047] (1) Drying of polyethylene masterbatch: Dry the polyethylene in an oven at 90°C for 5 hours to remove moisture and avoid bubbles during processing. After drying, cool the masterbatch to room temperature for later use;

[0048] (2) Dispersion treatment of photosensitizer: Cobalt acetylacetonate was mixed with ethanol and ultrasonically dispersed for 35 minutes to ensure that the photosensitizer was evenly dispersed; the dispersion was dried at 60° C. to remove the ethanol to obtain a powdered photosensitizer for later use;

[0049] (3) Preparation of premix: Add the dried polyethylene, triethyl citrate and 1010 antioxidant into a high-speed mixer; mix at 75° C. for 15 minutes to ensure that the components are evenly dispersed; melt-blend the premix through a twin-screw extruder at a temperature of 180° C. to obtain premix particles;

[0050] (4) Preparation of a mixture: adding the premix particles and the dispersed cobalt acetylacetonate, epoxysilane-modified nano-silica, and polycaprolactone into a high-speed mixer; mixing at 85° C. for 20 minutes to ensure that the components are evenly dispersed; and melt-blending the mixture through a twin-screw extruder at a temperature of 210° C. to obtain mixture particles;

[0051] (5) Film blowing: Add the mixed material particles into the hopper of the film blowing machine, control the barrel temperature of the film blowing temperature to 200°C; the die temperature is 220°C, adjust the stretch ratio of the film blowing machine to 3:1 and the blowing ratio to 2:1, and blow the mixed material into a film through the film blowing machine, and the film thickness is controlled at 30-40 μm;

[0052] (6) Plasma treatment: The film is passed through a plasma treatment device with a treatment power of 180 W and a treatment time of 2 minutes. Plasma treatment can improve the polarity and water resistance of the film surface;

[0053] (7) Fluorination treatment: The film was immersed in a fluorination treatment solution (ethanol solution of perfluorooctyltriethoxysilane) for 12 minutes, the film was taken out, and dried at 80°C for 1.5 hours to make the fluorination agent firmly adhere to the surface of the film;

[0054] (8) Cooling and winding:

[0055] The treated film was cooled to room temperature by a cooling roller, and the film was wound up using a winder with the winding tension controlled at 8N to avoid deformation of the film.

[0056] Example 3

[0057] This embodiment provides a highly waterproof photodegradable polyethylene film, which includes, by weight, 83 parts of polyethylene (PE), 3 parts of photosensitizer ferric acetylacetonate, 4 parts of waterproof enhancer aminosilane-modified nano-silica, 5 parts of plasticizer epoxy soybean oil, 5 parts of auxiliary degradation agent polycaprolactone, and 0.5 parts of 1010 antioxidant;

[0058] The method for preparing the above-mentioned highly waterproof photodegradable polyethylene film comprises the following steps:

[0059] (1) Drying of polyethylene masterbatch: Dry the polyethylene in an oven at 90°C for 5 hours to remove moisture and avoid bubbles during processing. After drying, cool the masterbatch to room temperature for later use;

[0060] (2) Dispersion treatment of photosensitizer: Mix ferric acetylacetonate and ethanol, and disperse by ultrasonic for 35 minutes to ensure that the photosensitizer is evenly dispersed; dry the dispersion at 60° C. to remove the ethanol, and obtain a powdered photosensitizer for later use;

[0061] (3) Preparation of premix: Add the dried polyethylene, epoxidized soybean oil and 1010 antioxidant into a high-speed mixer; mix at 75° C. for 15 minutes to ensure that the components are evenly dispersed; melt-blend the premix through a twin-screw extruder at a temperature of 180° C. to obtain premix particles;

[0062] (4) Preparation of a mixture: adding the premix particles and the dispersed ferric acetylacetonate, aminosilane-modified nano-silica, and polycaprolactone to a high-speed mixer; mixing at 85° C. for 20 minutes to ensure that the components are evenly dispersed; and melt-blending the mixture through a twin-screw extruder at a temperature of 210° C. to obtain mixture particles;

[0063] (5) Film blowing: Add the mixed material particles into the hopper of the film blowing machine, control the barrel temperature of the film blowing temperature to 200°C; the die temperature is 220°C, adjust the stretch ratio of the film blowing machine to 3:1 and the blowing ratio to 2:1, and blow the mixed material into a film through the film blowing machine, and the film thickness is controlled at 30-40 μm;

[0064] (6) Plasma treatment: The film is passed through a plasma treatment device with a treatment power of 180 W and a treatment time of 2 minutes. Plasma treatment can improve the polarity and water resistance of the film surface;

[0065] (7) Fluorination treatment: The film was immersed in a fluorination treatment solution (ethanol solution of perfluorooctyltriethoxysilane) for 12 minutes, the film was taken out, and dried at 80°C for 1.5 hours to make the fluorination agent firmly adhere to the surface of the film;

[0066] (8) Cooling and winding:

[0067] The treated film was cooled to room temperature by a cooling roller, and the film was wound up using a winder with the winding tension controlled at 8N to avoid deformation of the film.

[0068] Example 4

[0069] This embodiment provides a highly waterproof photodegradable polyethylene film, which includes, by weight, 75 parts of polyethylene (PE), 2 parts of photosensitizer ferric acetylacetonate, 3 parts of waterproof enhancer aminosilane-modified nano-silica, 5 parts of plasticizer epoxy soybean oil, 5 parts of auxiliary degradation agent polycaprolactone, and 0.5 parts of 1010 antioxidant;

[0070] The method for preparing the above-mentioned highly waterproof photodegradable polyethylene film comprises the following steps:

[0071] (1) Drying of polyethylene masterbatch: Dry the polyethylene in an oven at 90°C for 5 hours to remove moisture and avoid bubbles during processing. After drying, cool the masterbatch to room temperature for later use;

[0072] (2) Dispersion treatment of photosensitizer: Mix ferric acetylacetonate and ethanol, and disperse by ultrasonic for 35 minutes to ensure that the photosensitizer is evenly dispersed; dry the dispersion at 60° C. to remove the ethanol, and obtain a powdered photosensitizer for later use;

[0073] (3) Preparation of premix: Add the dried polyethylene, epoxidized soybean oil and 1010 antioxidant into a high-speed mixer; mix at 75° C. for 15 minutes to ensure that the components are evenly dispersed; melt-blend the premix through a twin-screw extruder at a temperature of 180° C. to obtain premix particles;

[0074] (4) Preparation of a mixture: adding the premix particles and the dispersed ferric acetylacetonate, aminosilane-modified nano-silica, and polycaprolactone to a high-speed mixer; mixing at 85° C. for 20 minutes to ensure that the components are evenly dispersed; and melt-blending the mixture through a twin-screw extruder at a temperature of 210° C. to obtain mixture particles;

[0075] (5) Film blowing: Add the mixed material particles into the hopper of the film blowing machine, control the barrel temperature of the film blowing temperature to 200°C; the die temperature is 220°C, adjust the stretch ratio of the film blowing machine to 3:1 and the blowing ratio to 2:1, and blow the mixed material into a film through the film blowing machine, and the film thickness is controlled at 30-40 μm;

[0076] (6) Plasma treatment: The film is passed through a plasma treatment device with a treatment power of 180 W and a treatment time of 2 minutes. Plasma treatment can improve the polarity and water resistance of the film surface;

[0077] (7) Fluorination treatment: The film was immersed in a fluorination treatment solution (ethanol solution of perfluorooctyltriethoxysilane) for 12 minutes, the film was taken out, and dried at 80°C for 1.5 hours to make the fluorination agent firmly adhere to the surface of the film;

[0078] (8) Cooling and winding:

[0079] The treated film was cooled to room temperature by a cooling roller, and the film was wound up using a winder with the winding tension controlled at 8N to avoid deformation of the film.

[0080] Comparative Example 1

[0081] This comparative example provides a highly waterproof photodegradable polyethylene film, which includes, by weight, 65 parts of polyethylene (PE), 2 parts of photosensitizer ferric acetylacetonate, 3 parts of waterproof enhancer aminosilane-modified nano-silica, 5 parts of plasticizer epoxy soybean oil, 3 parts of auxiliary degradation agent polycaprolactone, and 0.5 parts of 1010 antioxidant;

[0082] The method for preparing the above-mentioned highly waterproof photodegradable polyethylene film comprises the following steps:

[0083] (1) Drying of polyethylene masterbatch: Dry the polyethylene in an oven at 90°C for 5 hours to remove moisture and avoid bubbles during processing. After drying, cool the masterbatch to room temperature for later use;

[0084] (2) Dispersion treatment of photosensitizer: Mix ferric acetylacetonate and ethanol, and disperse by ultrasonic for 35 minutes to ensure that the photosensitizer is evenly dispersed; dry the dispersion at 60° C. to remove the ethanol, and obtain a powdered photosensitizer for later use;

[0085] (3) Preparation of premix: Add the dried polyethylene, epoxidized soybean oil and 1010 antioxidant into a high-speed mixer; mix at 75° C. for 15 minutes to ensure that the components are evenly dispersed; melt-blend the premix through a twin-screw extruder at a temperature of 180° C. to obtain premix particles;

[0086] (4) Preparation of a mixture: adding the premix particles and the dispersed ferric acetylacetonate, aminosilane-modified nano-silica, and polycaprolactone to a high-speed mixer; mixing at 85° C. for 20 minutes to ensure that the components are evenly dispersed; and melt-blending the mixture through a twin-screw extruder at a temperature of 210° C. to obtain mixture particles;

[0087] (5) Film blowing: Add the mixed material particles into the hopper of the film blowing machine, control the barrel temperature of the film blowing temperature to 200°C; the die temperature is 220°C, adjust the stretch ratio of the film blowing machine to 3:1 and the blowing ratio to 2:1, and blow the mixed material into a film through the film blowing machine, and the film thickness is controlled at 30-40 μm;

[0088] (6) Plasma treatment: The film is passed through a plasma treatment device with a treatment power of 180 W and a treatment time of 2 minutes. Plasma treatment can improve the polarity and water resistance of the film surface;

[0089] (7) Fluorination treatment: The film was immersed in a fluorination treatment solution (ethanol solution of perfluorooctyltriethoxysilane) for 12 minutes, the film was taken out, and dried at 80°C for 1.5 hours to make the fluorination agent firmly adhere to the surface of the film;

[0090] (8) Cooling and winding:

[0091] The treated film was cooled to room temperature by a cooling roller, and the film was wound up using a winder with the winding tension controlled at 8N to avoid deformation of the film.

[0092] Comparative Example 2

[0093] This comparative example provides a highly waterproof photodegradable polyethylene film, which includes, by weight, 90 parts by weight of polyethylene (PE), 2 parts by weight of photosensitizer ferric acetylacetonate, 3 parts by weight of waterproof enhancer aminosilane-modified nano-silica, 5 parts by weight of plasticizer epoxy soybean oil, 3 parts by weight of auxiliary degradation agent polycaprolactone, and 0.5 parts by weight of 1010 antioxidant;

[0094] The method for preparing the above-mentioned highly waterproof photodegradable polyethylene film comprises the following steps:

[0095] (1) Drying of polyethylene masterbatch: Dry the polyethylene in an oven at 90°C for 5 hours to remove moisture and avoid bubbles during processing. After drying, cool the masterbatch to room temperature for later use;

[0096] (2) Dispersion treatment of photosensitizer: Mix ferric acetylacetonate and ethanol, and disperse by ultrasonic for 35 minutes to ensure that the photosensitizer is evenly dispersed; dry the dispersion at 60° C. to remove the ethanol, and obtain a powdered photosensitizer for later use;

[0097] (3) Preparation of premix: Add the dried polyethylene, epoxidized soybean oil and 1010 antioxidant into a high-speed mixer; mix at 75° C. for 15 minutes to ensure that the components are evenly dispersed; melt-blend the premix through a twin-screw extruder at a temperature of 180° C. to obtain premix particles;

[0098] (4) Preparation of a mixture: adding the premix particles and the dispersed ferric acetylacetonate, aminosilane-modified nano-silica, and polycaprolactone to a high-speed mixer; mixing at 85° C. for 20 minutes to ensure that the components are evenly dispersed; and melt-blending the mixture through a twin-screw extruder at a temperature of 210° C. to obtain mixture particles;

[0099] (5) Film blowing: Add the mixed material particles into the hopper of the film blowing machine, control the barrel temperature of the film blowing temperature to 200°C; the die temperature is 220°C, adjust the stretch ratio of the film blowing machine to 3:1 and the blowing ratio to 2:1, and blow the mixed material into a film through the film blowing machine, and the film thickness is controlled at 30-40 μm;

[0100] (6) Plasma treatment: The film is passed through a plasma treatment device with a treatment power of 180 W and a treatment time of 2 minutes. Plasma treatment can improve the polarity and water resistance of the film surface;

[0101] (7) Fluorination treatment: The film was immersed in a fluorination treatment solution (ethanol solution of perfluorooctyltriethoxysilane) for 12 minutes, the film was taken out, and dried at 80°C for 1.5 hours to make the fluorination agent firmly adhere to the surface of the film;

[0102] (8) Cooling and winding:

[0103] The treated film was cooled to room temperature by a cooling roller, and the film was wound up using a winder with the winding tension controlled at 8N to avoid deformation of the film.

[0104] Comparative Example 3

[0105] This comparative example is carried out on the basis of the above-mentioned embodiment 1, and the similarities with the above-mentioned embodiment are not repeated here.

[0106] In this comparative example, there is no photosensitizer and no waterproof enhancer.

[0107] Comparative Example 4

[0108] This comparative example is carried out on the basis of the above-mentioned embodiment 1, and the similarities with the above-mentioned embodiment are not repeated here.

[0109] In this comparative example, there is no waterproof enhancer.

[0110] Comparative Example 5

[0111] This comparative example is carried out on the basis of the above-mentioned embodiment 1, and the similarities with the above-mentioned embodiment are not repeated here.

[0112] In this comparative example, there is no photosensitizer.

[0113] The polyethylene film products prepared in the above examples and comparative examples were tested, and the test results are shown in Table 1.

[0114] Table 1

[0115]

[0116] It can be seen from Table 1 that the addition amount of each substance will affect the performance of the polyethylene film product. It can be seen from the examples and comparative examples 3 to 5 that not adding a waterproof enhancer and / or a photosensitizer will weaken the performance of the polyethylene film product.

[0117] In summary, the highly waterproof photodegradable polyethylene film of the present invention has high waterproofness. By adding modified nano-silicon dioxide and combining surface treatment technology, the waterproof performance of the film is significantly improved; the water contact angle is ≥115°, and the water vapor permeability is ≤5g / m 2 ·24h, suitable for application in humid environments; the invention realizes controllable photodegradation of the film by adding photosensitizer and auxiliary degradation agent. Under natural light, the degradation rate is ≥60% within 90 days, which solves the environmental problem that traditional plastic films are difficult to degrade and can be degraded in the natural environment, reducing "white pollution". The degradation products are harmless to the environment and meet environmental protection requirements; the high water-repellent photodegradable polyethylene film of the invention has excellent mechanical properties. By optimizing the formula and process, the tensile strength of the film is ≥20MPa and the elongation at break is ≥300%, which meets the needs of various application scenarios; the preparation process of the high water-repellent photodegradable polyethylene film of the invention has low energy consumption, and no harmful gas is generated during the degradation process, which helps to reduce carbon emissions; the preparation process of the high water-repellent photodegradable polyethylene film of the invention is simple, easy to industrialize, and has a wide range of applications. It can be applied to food packaging, electronic product packaging, etc., provides high water-repellency and environmental protection, is suitable for agricultural covering film, increases crop yield, and reduces farmland plastic pollution at the same time, is suitable for medical packaging materials, and has both water-repellency and biocompatibility.

[0118] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A highly waterproof photodegradable polyethylene film, characterized in that: Calculated by weight, it includes 70-85 parts by weight of polyethylene, 1-3 parts by weight of photosensitizer, 2-5 parts by weight of waterproof enhancer, 3-8 parts by weight of plasticizer, 5-10 parts by weight of auxiliary degradation agent, and 0.5-1 part by weight of antioxidant.

2. A highly waterproof photodegradable polyethylene film as claimed in claim 1, characterized in that: The photosensitizer is selected from one of ferric acetylacetonate, ferrocene, ammonium ferric oxalate, cobalt acetylacetonate, cobalt chloride, cobalt oxalate, manganese acetylacetonate, nickel acetylacetonate, and copper acetylacetonate.

3. A highly waterproof photodegradable polyethylene film as claimed in claim 1, characterized in that: The waterproof enhancer is modified nano-silica, and the modified nano-silica is selected from one or more of aminosilane-modified nano-silica, epoxysilane-modified nano-silica, methacryloxysilane-modified nano-silica, hexadecyltrimethoxysilane-modified nano-silica, perfluorooctyltriethoxysilane-modified nano-silica, polymethyl methacrylate-grafted nano-silica, and polystyrene-grafted nano-silica.

4. A highly waterproof photodegradable polyethylene film as claimed in claim 1, characterized in that: The plasticizer is selected from one of epoxy soybean oil, epoxy linseed oil, triethyl citrate, tributyl citrate, acetyl tributyl citrate, acetylated monoglyceride, and epoxy fatty acid methyl ester.

5. The highly waterproof photodegradable polyethylene film according to claim 1, characterized in that: The auxiliary degradation agent is selected from one of microcrystalline cellulose, carboxymethyl cellulose, starch, polylactic acid, chitosan, soybean protein, corn protein, polycaprolactone, polyhydroxyalkanoate, polybutylene succinate, ferric acetylacetonate, and cobalt acetylacetonate.

6. A highly waterproof photodegradable polyethylene film as claimed in claim 1, characterized in that: The antioxidant is selected from one of 2,6-di-tert-butyl-p-cresol, 1010 antioxidant, 1076 antioxidant, triphenyl phosphate, 168 antioxidant, tris(nonylphenyl) phosphite, and vitamin E.

7. A method for preparing a highly water-resistant photodegradable polyethylene film according to any one of claims 1 to 6, characterized in that: The steps include: (1) Drying of polyethylene masterbatch: Dry the polyethylene in an oven at 80°C to 100°C for 4 to 6 hours to remove moisture. After drying, cool the masterbatch to room temperature for standby use; (2) Dispersion treatment of photosensitizer: Mix the photosensitizer with ethanol and perform ultrasonic dispersion for 30 to 35 minutes to ensure that the photosensitizer is evenly dispersed; dry the dispersion at 60 to 63° C. to remove the ethanol and obtain a powdered photosensitizer for later use; (3) Preparation of premix: adding the dried polyethylene, plasticizer and antioxidant into a high-speed mixer; mixing at 60° C. to 80° C. for 10 to 15 minutes to ensure uniform dispersion of the components; melt blending the premix through a twin-screw extruder at a temperature of 160° C. to 200° C. to obtain premix particles; (4) Preparation of a mixture: adding premix particles, photosensitizer, waterproof enhancer, and auxiliary degradation agent to a high-speed mixer; mixing at 80° C. to 100° C. for 15 to 20 minutes to ensure uniform dispersion of the components; melt blending the mixture through a twin-screw extruder at a temperature of 180° C. to 220° C. to obtain mixture particles; (5) Film blowing: Add the mixed material particles into the hopper of the film blowing machine, control the film blowing temperature, adjust the stretch ratio and inflation ratio of the film blowing machine, and blow the mixed material into a film through the film blowing machine. The film thickness is controlled at 20 to 50 μm. (6) Plasma treatment: the film is passed through a plasma treatment device with a treatment power of 100 to 200 W and a treatment time of 1 to 3 minutes; (7) Fluorination treatment: immerse the film in a fluorination treatment solution for 10 to 15 minutes, take out the film, and dry it at 80 to 85°C for 1 to 2 hours to allow the fluorination agent to firmly adhere to the surface of the film; (8) Cooling and winding: The treated film is cooled to room temperature by a cooling roller, and the film is wound up using a winder, and the winding tension is controlled at 5 to 10N to avoid deformation of the film.

8. The method for preparing a highly waterproof photodegradable polyethylene film according to claim 7, characterized in that: In step (5), the barrel temperature for controlling the film blowing temperature is 190°C to 210°C; the die head temperature is 200°C to 220°C, the stretch ratio of the film blowing machine is adjusted to 2 to 4:1, and the inflation ratio is adjusted to 2 to 3:1.

Images