Multi-layer co-extrusion film for aquaculture winter shed and preparation method of multi-layer co-extrusion film

Abstract

The invention relates to the field of plastic film forming and processing, and discloses a multi-layer co-extrusion film for an aquaculture winter shed and a preparation method of the multi-layer co-extrusion film. The inner layer comprises the following components in percentage by weight: 63 to 71 percent of composite metallocene low-density polyethylene, 10 to 20 percent of low-density polyethylene, 5 to 10 percent of modified toughening master batch, 5 to 8 percent of fog dispersal dripping agent, 0.5 to 1 percent of ultraviolet light stabilizer, 0.5 to 1 percent of ultraviolet light absorber, 0.2 to 0.5 percent of antioxidant and 2.5 to 5 percent of processing aid; the modified toughening master batch contains ethylene propylene diene monomer, and the fog dispersal dripping agent is prepared by melt extrusion and granulation of a styrene-octylene-glycidyl methacrylate copolymer, a vinyl elastomer, acrylic acid modified silicone, long-chain carboxylate polyoxyethylene and pentaerythritol stearate. The composite material has the advantages of good anti-dripping, anti-puncture and tearing strength, good low-temperature toughness and difficulty in cracking or damage.

Description

Technical Field

[0001] This application relates to the field of plastic film molding and processing, and in particular to a multilayer co-extruded film for winter sheds in aquaculture and its preparation method. Background Technology

[0002] Winter greenhouse film for aquaculture is a key material for overwintering temperature-sensitive species such as shrimp. Its core function is to create a controllable greenhouse microclimate, offering the following key advantages: First, excellent heat insulation performance, effectively preventing heat loss from the water inside the greenhouse via far-infrared radiation, significantly reducing heating energy consumption and ensuring the safe overwintering of farmed organisms; second, superior anti-drip and anti-fogging properties, preventing water vapor from condensing on the inner surface and dripping directly, avoiding disturbing the farmed organisms and causing stress, while maintaining stable light transmittance inside the greenhouse; third, high strength and high weather resistance, able to withstand harsh environments such as strong winds, hail, high salt spray, and ultraviolet aging in coastal areas.

[0003] Currently, existing high-performance aquaculture winter greenhouse films are mainly prepared using a three- or five-layer co-extrusion blow molding process. The structure, from the outside in, consists of a weather-resistant layer, an adhesive layer, a heat-insulating core layer, another adhesive layer, and a functional inner layer. The functional inner layer, directly exposed to the high-humidity environment inside the greenhouse, is crucial in determining the film's puncture resistance, tear resistance, and persistent dripping performance. In existing technologies, this inner layer typically uses linear low-density polyethylene or ethylene-vinyl acetate copolymer as the base resin, and drip-reducing agents, such as monoglyceride stearate and Tween, are added through blending. The preparation method involves metering and melt-blending the above raw materials, then introducing them along with the melt of other functional layers into a multi-layer co-extrusion die, followed by blowing, cooling, traction, and winding.

[0004] However, existing aquaculture winter greenhouse films, especially their functional inner layers, still suffer from the following technical defects that urgently need to be addressed: First, mechanical durability and functional longevity are difficult to coordinate. The compatibility between conventional inner layer resins and anti-drip agents is limited. To maintain surface efficacy, the anti-drip agent needs to continuously migrate and precipitate outwards. This process leads to the gradual deterioration of the inner layer resin, causing its anti-drip performance to decrease under the combined effects of gravity-induced wetting from condensate inside the greenhouse and external wind loads over a long period. Furthermore, its puncture and tear resistance decreases too rapidly, making the film prone to accidental damage in the later stages of aquaculture, posing a significant aquaculture risk. Second, low-temperature toughness is insufficient. Existing inner layer formulations show a significant decrease in flexibility under extreme low-temperature conditions in winter, causing the film to harden and become brittle, making it more susceptible to cracking and damage during installation or in windy weather. Summary of the Invention

[0005] To address the problems that existing aquaculture winter greenhouse films suffer from reduced anti-drip performance, rapid decline in puncture and tear resistance, and insufficient low-temperature toughness, leading to cracking and damage under long-term exposure to gravity-driven condensate and external wind loads, this application provides a multilayer co-extruded film for aquaculture winter greenhouses and its preparation method.

[0006] In the first aspect, this application provides a multilayer co-extruded film for winter sheds in aquaculture, employing the following technical solution: A multi-layer co-extruded film for winter sheds in aquaculture is produced by co-extruding and blowing an outer layer, a first adhesive layer, a middle layer, a second adhesive layer, and an inner layer. The inner layer is made from the following raw materials by weight percentage: Composite metallocene low-density polyethylene 63-71% Low-density polyethylene 10-20% Modified toughening masterbatch 5-10% Anti-fogging and anti-dripping agent 5-8% UV stabilizer 0.5-1% UV absorber 0.5-1% Antioxidant 0.2-0.5% Processing aids 2.5-5%; The composite metallocene low-density polyethylene is composed of metallocene low-density polyethylene A, metallocene low-density polyethylene B, and metallocene low-density polyethylene C in a weight ratio of (1.5-2.5):1:(0.2-0.35). The melt index of metallocene low-density polyethylene A is 0.3-0.8 g / 10min, the melt index of metallocene low-density polyethylene B is 1-1.7 g / 10min, and the melt index of metallocene low-density polyethylene C is 3.8-4.5 g / 10min. The modified toughening masterbatch contains ethylene propylene diene monomer (EPDM) rubber. The anti-fogging and anti-dripping agent is obtained by melt extrusion and granulation of styrene-octene-glycidyl methacrylate copolymer, vinyl elastomer, acrylic modified silicone, long-chain carboxylic acid ester polyoxyethylene, and pentaerythritol stearate.

[0007] By adopting the above technical solutions, the composite metallocene low-density polyethylene is composed of metallocene low-density polyethylene A, metallocene low-density polyethylene B, and metallocene low-density polyethylene C in specific proportions and melt indices. This provides the inner layer with good mechanical and processing properties, and the combination of different melt indices ensures suitable flowability and formability of the film during extrusion and blown film production. The synergistic effect of low-density polyethylene and modified toughening masterbatch further improves the flexibility and processing performance of the inner layer. The anti-fogging and anti-dripping agent, styrene-octene-glycidyl methacrylate copolymer, vinyl elastomer, acrylic-modified silicone, long-chain carboxylic acid ester polyoxyethylene, and pentaerythritol stearate, is obtained by melt extrusion and granulation. This effectively prevents water vapor from condensing on the inner surface of the greenhouse, maintaining stable light transmittance. UV stabilizers and UV absorbers absorb and shield ultraviolet rays, reducing the aging effect of UV rays on the film and improving its weather resistance. Antioxidants prevent oxidation of the film during processing and use, extending its service life. Processing aids further enhance the processing stability of the film. The composite metallocene low-density polyethylene (MDPE) and the anti-fogging / drip agent work synergistically. The MDPE provides an excellent carrier for the anti-fogging / drip agent, allowing it to disperse more evenly within the inner layer. Its structure also facilitates the slow and persistent migration of the anti-fogging / drip agent to the film surface, ensuring its continued effectiveness during long-term use. Simultaneously, the anti-fogging / drip agent further enhances the mechanical properties of the MDPE, guaranteeing the film's puncture and tear resistance.

[0008] The film prepared in this application has excellent anti-drip and anti-fogging properties, which can maintain the light transmittance inside the greenhouse for a long time; it has good mechanical durability, and its puncture resistance and tear resistance decay slowly. It is not easily damaged even under the combined action of gravity wetting of condensate inside the greenhouse and external wind load for a long time; it also has good low temperature toughness, and it is not easy to crack or be damaged in extreme low temperature environments in winter, which can effectively ensure the safety and stability of aquaculture.

[0009] Preferably, the anti-fogging and anti-dripping agent is prepared from the following raw materials by weight percentage: 60-70% styrene-octene-glycidyl methacrylate copolymer Vinyl elastomer 22-30% Acrylic modified silicone 2-4% Long-chain carboxylic acid esters, polyoxyethylene, 1.5-2.5% Pentaerythritol stearate 3-4.5%.

[0010] By adopting the above technical solution, the styrene-octene-glycidyl methacrylate copolymer content in the anti-fogging and anti-dripping agent is 60-70%, which provides a good matrix structure, enhances compatibility with other raw materials, and helps other components to be uniformly dispersed in the inner layer; the vinyl elastomer content is 22-30%, which can impart a certain elasticity to the inner layer, improve its tear resistance and flexibility, and reduce the risk of breakage due to external forces during use; the acrylic modified silicone content is 2-4%, which has good leveling and lubrication properties, and can improve the smoothness of the inner layer surface. It facilitates the flow of water droplets on the surface, improving the anti-fogging and anti-dripping effect; the long-chain carboxylic acid ester polyoxyethylene content is 1.5-2.5%, which has good water-oil amphiphilicity. It can be stably dispersed in the inner layer while attracting and dispersing water vapor, preventing water vapor from condensing into large water droplets on the film surface, further enhancing the anti-dripping performance; the pentaerythritol stearate content is 3-4.5%, which can act as a surfactant to reduce surface tension, making water droplets easier to spread and improving the anti-fogging effect. At the same time, its fatty acid ester structure is stably interwoven and dispersed in the inner layer, improving the dispersion uniformity. These substances work synergistically to improve the anti-fogging and anti-dripping performance, tear resistance, and flexibility of the inner layer, solving the problems of reduced anti-dripping performance, rapid decline in puncture and tear resistance, and insufficient low-temperature toughness of existing aquaculture winter greenhouse films.

[0011] Preferably, the anti-fogging and anti-dripping agent is prepared by the following steps: First, styrene-octene-glycidyl methacrylate copolymer and long-chain carboxylic acid ester polyoxyethylene are mixed. Then, vinyl elastomer, acrylic modified silicone and pentaerythritol stearate are added and mixed. The mixture is then melt-extruded and granulated to obtain an anti-fogging and anti-dripping agent.

[0012] By adopting the above technical solution, the styrene-octene-glycidyl methacrylate copolymer and long-chain carboxylic acid ester polyoxyethylene are first mixed to fully integrate the two raw materials and form a stable basic system. Then, vinyl elastomer, acrylic modified silicone and pentaerythritol stearate are added and mixed to ensure that these components are uniformly dispersed in the formed basic system, ensuring that the performance of each component is fully utilized. Finally, melt extrusion and granulation are performed to obtain uniform anti-fogging and anti-dripping agent particles, which can better mix with other raw materials in the inner layer, improve the overall anti-fogging and anti-dripping performance of the inner layer, and enhance the compatibility with the inner layer resin.

[0013] Preferably, the melt extrusion temperature is 160-200℃.

[0014] By adopting the above technical solution, the optimal melting temperature is beneficial to the full melting and dispersion of each component in the anti-fogging and anti-dripping agent.

[0015] Preferably, the low-density polyethylene is composed of C4 linear low-density polyethylene and C6 linear low-density polyethylene in a weight ratio of 1:(2-4).

[0016] By adopting the above technical solution, the two types of linear low-density polyethylene work synergistically to improve the mechanical and processing properties of the inner layer and enhance the puncture and tear resistance of the film.

[0017] Preferably, the ultraviolet light stabilizer is a hindered amine stabilizer, and the ultraviolet light absorber is any one or a combination of benzotriazole absorbers, benzophenone absorbers, and triazine absorbers.

[0018] By adopting the above technical solution and using hindered amine stabilizers as ultraviolet light stabilizers, free radicals generated by photo-oxidation can be effectively captured, photo-oxidation reactions can be inhibited, and the photo-aging resistance of the film can be improved. By selecting any one or a combination of benzotriazole absorbers, benzophenone absorbers, and triazine absorbers as ultraviolet light absorbers, ultraviolet rays can be absorbed and converted into heat energy for release, reducing the damage of ultraviolet rays to the film, further enhancing the film's resistance to ultraviolet rays, and extending the film's service life.

[0019] Preferably, the antioxidant is antioxidant 1010 and / or antioxidant 168.

[0020] By adopting the above technical solution, using antioxidant 1010 and / or antioxidant 168 as antioxidants for the inner layer of multilayer co-extruded film for winter sheds in aquaculture can prevent the inner layer raw materials from deteriorating due to oxidation during processing and use, and avoid the film from experiencing rapid decline in puncture resistance and tear resistance as well as reduced anti-dripping performance due to oxidation during long-term use.

[0021] Preferably, the processing aid includes an opening agent and a lubricant, wherein the opening agent is one of fumed silica or organosilicon microspheres, and the lubricant is any one of polyethylene wax, calcium stearate, zinc stearate, or erucamide.

[0022] By adopting the above technical solutions, the use of an opening agent can prevent the films from sticking together during storage and use, ensuring that the films can be smoothly unfolded and used; the use of a lubricant can reduce the frictional resistance of the raw materials during processing, making the raw materials easier to melt, extrude and flow in the multi-layer co-extrusion blown film machine, improving processing efficiency, and at the same time improving the smoothness and film-forming properties of the film surface.

[0023] Secondly, this application provides a method for preparing a multilayer co-extruded film for winter sheds in aquaculture, using the following technical solution: A method for preparing a multilayer co-extruded film for winter sheds in aquaculture, comprising the following steps; The raw materials for each layer are melted separately, and then extruded, cooled, blown by an air ring, corona-treated, and wound up using a multi-layer co-extrusion blown film machine to produce a multi-layer co-extruded film for aquaculture.

[0024] By employing the above technical solutions, melting each layer of raw material separately allows them to reach a suitable fluid state for processing, facilitating subsequent extrusion molding. Using a multi-layer co-extrusion blown film machine for melt extrusion enables the raw materials to be uniformly bonded together under pressure and temperature, forming a multi-layered film preform. Cooling air ring blowing allows for rapid cooling and shaping of the high-temperature film preform, ensuring the film's dimensional stability and physical properties. Corona treatment improves the film's surface roughness and polarity, enhancing its adhesion to surface coating materials such as printing inks and adhesives.

[0025] Preferably, the melt extrusion temperature is 150-200℃, the blow-up ratio is (2.5-3):1, and the draw ratio is (10-12):1.

[0026] By adopting the above technical solution, the optimal melt extrusion temperature can fully melt each layer of raw material and maintain good fluidity, which is beneficial to subsequent extrusion and molding. The blow-up ratio is controlled at (2.5-3):1 and the draw ratio is controlled at (10-12):1, which can make the film obtain appropriate stretching in both the transverse and longitudinal directions, so that the film has uniform thickness and good mechanical properties, and improves the film's puncture resistance, tear resistance and low temperature toughness.

[0027] In summary, this application includes at least one of the following beneficial technical effects: 1. The multi-layer co-extruded film for aquaculture winter sheds of this application is made by extruding and blowing film together an outer layer, a first adhesive layer, a middle layer, a second adhesive layer and an inner layer. The inner layer is a composite metallocene low-density polyethylene composed of metallocene low-density polyethylene A, metallocene low-density polyethylene B and metallocene low-density polyethylene C, and is combined with low-density polyethylene, modified toughening masterbatch, anti-fogging and anti-dripping agent, ultraviolet light stabilizer, ultraviolet light absorber, antioxidant and processing aid, which solves the problem of difficulty in synergistic mechanical durability and functional durability, avoids the precipitation of anti-dripping agent and plasticizer that makes the winter shed film brittle, and improves anti-dripping performance, puncture resistance and tear resistance.

[0028] 2. The anti-fogging and anti-dripping agent is made by melt extrusion and granulation of styrene-octene-glycidyl methacrylate copolymer, vinyl elastomer, acrylic modified silicone, long-chain carboxylic acid ester polyoxyethylene and pentaerythritol stearate, which ensures the excellent anti-fogging and anti-dripping performance of the film and prevents water vapor inside the shed from condensing on the inner surface and forming water droplets that drip directly down.

[0029] 3. Low-density polyethylene is composed of C4 linear low-density polyethylene and C6 linear low-density polyethylene, which can improve the mechanical properties and processing properties of the inner layer and enhance the puncture resistance and tear resistance of the film.

[0030] 4. The preparation method involves melting each layer of raw materials separately, extruding them using a multi-layer co-extrusion blown film machine, followed by cooling air ring blowing, corona treatment, and winding. This process ensures that the raw materials of each layer are fully integrated and composited, guaranteeing the performance and quality of the film. Detailed Implementation

[0031] The present application will be further described in detail below with reference to the embodiments.

[0032] The following are some of the sources and specifications of the raw materials used in this application. The raw materials used in the preparation examples and embodiments of this application can all be obtained commercially, including but not limited to the following models and manufacturers of raw materials. Raw materials with equivalent performance can also be used: 1. Metallocene low-density polyethylene A: ExxonMobil Exceed™ Tough+ m 0814.RS, melt flow index 0.8 g / 10 min; ExxonMobil Exceed™ Tough+ m 0518.RL, melt flow index 0.5 g / 10 min; ExxonMobil Exceed™ Tough+ m 0211.RA, melt flow index 0.2 g / 10 min; 2. Metallocene low-density polyethylene B: ExxonMobil Exceed™ Flow m 1716.RA, melt flow index 1.7 g / 10 min; ExxonMobil Exceed™ Flow m 1020.RA, melt flow index 1 g / 10 min; 3. Metallocene low-density polyethylene C: ExxonMobil Exceed™ Tough m 4536.PA, melt flow index 4.5 g / 10 min; ExxonMobil Exceed™ Tough m 3812.PA, melt flow index 3.8 g / 10 min; 4. Styrene-octene-glycidyl methacrylate copolymer: Jia Yi Rong brand, SOG-02; 5. Vinyl elastomer: ExxonMobil Exxtra™ Seal POP 2008.RA; 6. Acrylic-modified silicone: Shin-Etsu R170S; 7. Long-chain carboxylic acid ester polyoxyethylene: Xima LMEO-18; 8. C4 linear low-density polyethylene: ExxonMobil™ C4LL 1018.AN Wire & Cable, melt flow index 1.0 g / 10min; 9. C6 linear low-density polyethylene: ExxonMobil™ C6LL 0825.69, melt index 0.8 g / 10 min; 10. Modified toughening masterbatch: Guangdong Dicai New Materials Co., Ltd., model 82270, containing 50wt% EPDM rubber.

[0033] Preparation example of anti-fogging and anti-dripping agent Preparation Example 1 Preparation Example 1 discloses an anti-fogging and anti-dripping agent, which is prepared by the following steps: First, 6 kg of styrene-octene-glycidyl methacrylate copolymer and 0.15 kg of long-chain carboxylic acid ester polyoxyethylene were mixed. Then, 3 kg of vinyl elastomer, 0.4 kg of acrylic acid modified silicone and 0.45 kg of pentaerythritol stearate were added and mixed. The mixture was melt-extruded using a screw extruder, and the extrusion conditions were controlled as follows: Zone 1 extrusion temperature 160℃, Zone 2 extrusion temperature 180℃, Zone 3 extrusion temperature 190℃, Zone 4 extrusion temperature 200℃, Zone 5 extrusion temperature 190℃ and Zone 6 extrusion temperature 180℃. After water cooling and pelletizing, the anti-fogging and anti-dripping agent was obtained.

[0034] Preparation Examples 2-3 The difference between Preparation Example 2-3 and Preparation Example 1 lies in the amount of raw materials used and the preparation conditions, as detailed in Table 1 below.

[0035] Table 1. Parameters for Preparation Examples 1-3

[0036] Preparation of Comparative Example 1 The difference between Comparative Example 1 and Preparation Example 1 is that the styrene-octene-glycidyl methacrylate copolymer was replaced with an equal amount of vinyl elastomer, while the rest was the same as Preparation Example 1.

[0037] Preparation of Comparative Example 2 The difference between Comparative Example 2 and Preparation Example 1 is that the acrylic modified silicone was replaced with an equal amount of polyethylene wax, which was Honeywell A-C629. Otherwise, they were the same as in Preparation Example 1.

[0038] Preparation of Comparative Example 3 The difference between Comparative Example 3 and Preparation Example 1 is that the long-chain carboxylic acid ester polyoxyethylene is replaced with pentaerythritol stearate in equal amounts, while the rest is the same as Preparation Example 1.

[0039] Preparation of Comparative Example 4 The difference between Comparative Example 4 and Preparation Example 1 is that pentaerythritol stearate was replaced with monoglyceride stearate in equal amounts, while the rest was the same as Preparation Example 1.

[0040] Preparation of Comparative Example 5 The difference between Comparative Example 5 and Preparation Example 1 is that the long-chain carboxylic acid ester polyoxyethylene is replaced with an equal amount of Tween 60, otherwise it is the same as Preparation Example 1.

[0041] Example

[0042] Example 1

[0043] Example 1 discloses a method for preparing a multilayer co-extruded film for aquaculture, which is obtained by the following steps; The raw materials in each layer are melted separately at the following temperatures: Zone 1 150℃, Zone 2 165℃, Zone 3 180℃, Zone 4 200℃, Zone 5 190℃, and Zone 6 180℃. Outer layer: 7 kg of metallocene low-density polyethylene A with a melt index of 0.8 g / 10 min, 1.5 kg of C6 linear low-density polyethylene with a melt index of 0.8 g / 10 min, 1 kg of modified toughening masterbatch, 0.2 kg of acrylic modified silicone, 0.1 kg of UV770 as a UV stabilizer, 0.1 kg of 2,2',4,4'-tetrahydroxybenzophenone as a UV absorber, 0.05 kg of antioxidant (antioxidant 1010 and antioxidant 168 = 1:1) and 0.05 kg of erucamide as a lubricant; First adhesive layer and second adhesive layer: 9.7 kg vinyl elastomer, 0.1 kg UV770 as ultraviolet light stabilizer, 0.1 kg 2,2',4,4'-tetrahydroxybenzophenone as ultraviolet light absorber and 0.1 kg erucamide as lubricant; Intermediate layer: 8 kg of C6 linear low-density polyethylene with a melt index of 0.8 g / 10 min, 1.5 kg of ethylene-vinyl acetate copolymer, 0.1 kg of UV770 as a UV stabilizer, 0.1 kg of 2,2',4,4'-tetrahydroxybenzophenone as a UV absorber, and 0.1 kg of erucamide as a lubricant. The ethylene-vinyl acetate copolymer is ExxonMobil™ EVA 03006, with a vinyl acetate content of 6 wt% and a melt index of 0.3 g / 10 min. Inner layer: 6.3 kg composite metallocene low-density polyethylene, 1.5 kg low-density polyethylene, 0.73 kg modified toughening masterbatch, 0.8 kg anti-fogging and anti-dripping agent prepared in Example 1, 0.05 kg ultraviolet light stabilizer, 0.1 kg ultraviolet light absorber, 0.02 kg antioxidant, 0.5 kg processing aid; In the inner layer, the composite metallocene low-density polyethylene is composed of metallocene low-density polyethylene A, metallocene low-density polyethylene B, and metallocene low-density polyethylene C in a weight ratio of 1.5:1:0.2. The melt index of metallocene low-density polyethylene A is 0.2 g / 10 min, the melt index of metallocene low-density polyethylene B is 1.7 g / 10 min, and the melt index of metallocene low-density polyethylene C is 3.8 g / 10 min. The low-density polyethylene is composed of C4 linear low-density polyethylene and C6 linear low-density polyethylene in a weight ratio of 1:4. The ultraviolet light stabilizer is UV770, and the ultraviolet light absorber is 2,2',4,4'-tetrahydroxybenzophenone. The antioxidant is composed of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1. The processing aids include 0.2 kg of opening agent and 0.3 kg of lubricant. The opening agent is fumed silica with a particle size of 30-50 nm, and the lubricant is erucamide. The film was then extruded using a multi-layer co-extrusion blown film machine. During extrusion, the thickness ratio of the outer layer, the first adhesive layer, the middle layer, the second adhesive layer, and the inner layer was 1:0.4:0.8:0.4:1.2. The film was blown by a cooling air ring with a blow-up ratio of 2.5:1 and a stretch ratio of 12:1. After corona treatment and winding, a multi-layer co-extruded film for aquaculture was obtained.

[0044] Example 2-3 The difference between Examples 2-3 and Example 1 is that the raw material composition and dosage of the inner layer are different, and the blown film parameters are different, as detailed in Table 2 below.

[0045] Table 2. Difference Parameters between Examples 1-3

[0046] Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the anti-fogging and anti-dripping agent was derived from the preparation of Comparative Example 1, while the rest is the same as Example 1.

[0047] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the anti-fogging and anti-dripping agent was derived from the preparation of Comparative Example 2, while the rest is the same as Example 1.

[0048] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the anti-fogging and anti-dripping agent was derived from the preparation of Comparative Example 3, while the rest is the same as Example 1.

[0049] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the anti-fogging and anti-dripping agent was derived from the preparation of Comparative Example 4, while the rest is the same as Example 1.

[0050] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that the anti-fogging and anti-dripping agent was derived from the preparation of Comparative Example 5, while the rest is the same as Example 1.

[0051] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that metallocene low-density polyethylene C is replaced with metallocene low-density polyethylene B in equal amounts, while the rest is the same as Example 1.

[0052] Comparative Example 7 The difference between Comparative Example 7 and Example 1 is that the modified toughening masterbatch was replaced with an equal amount of low-density polyethylene, while the rest was the same as Example 1.

[0053] Performance testing The following tests were conducted on the performance of the multilayer co-extruded films for winter aquaculture sheds prepared in Examples 1-3 and Comparative Examples 1-7: Film thickness: 0.072 mm; 1. Right-angle tear strength test Referencing the test methods in Section 7.7 of GB / T4455-2019 and QB / T 1130-1991, the test speed was 200 mm / min, the test environment was 25℃ room temperature +50RH%, the transverse tear strength of the film (unit: kN / m) was tested, and the test results were recorded.

[0054] 2. Puncture strength test Refer to the test method in Section 6.6.16 of GB / T10004-2008, test speed 50 mm / min, test environment 25℃ room temperature +50RH%, test the puncture strength of the film (unit: N), and record the test results.

[0055] 3. Dart impact strength test The test was conducted according to Method A in GB / T 9639.1-2008. Twenty samples were tested at a room temperature of 25℃ + 50% RH. The impact fracture mass (unit: g) of the film was measured and the test results were recorded.

[0056] 4. Low temperature resistance test The film was placed at a temperature of -20℃ for 7 days. Then, according to the test methods in Section 7.7 of GB / T4455-2019 & QB / T 1130-1991, the test speed was 200mm / min, the test environment was 25℃ room temperature +50RH%, and the change rate of transverse tear strength of the film was measured (unit: %). The change rate of transverse tear strength = (before test - after test) / before test * 100%. The test results were recorded.

[0057] 5. Anti-drip performance test The film was placed in a UV340 ultraviolet test chamber at a temperature of 70℃ and a humidity of 80% for 30 days. The water droplet angle of the film (unit: °) was measured and the test results were recorded.

[0058] The following are the performance test data of the multilayer co-extruded films for aquaculture winter sheds prepared in Examples 1-3 and Comparative Examples 1-7. Please refer to Table 3 below for details.

[0059] Table 3 Performance data of multilayer co-extruded films for aquaculture winter sheds prepared in Examples 1-3 and Comparative Examples 1-7

[0060] Based on Examples 1-3 and Comparative Examples 1-5, and in conjunction with Table 3, it can be concluded that the anti-fogging and anti-dripping agent prepared using the specific proportions of this application can significantly improve the anti-dripping properties of the prepared film, while also enhancing the mechanical properties of the film. In Comparative Example 1, replacing an equal amount of styrene-octene-glycidyl methacrylate copolymer with vinyl elastomer significantly reduced the mechanical properties of the prepared film. Furthermore, after low-temperature testing, the tear strength was significantly reduced, and the water droplet angle increased, possibly due to a decrease in the dispersion and bonding performance of the anti-fogging and anti-dripping agent with the system. In Comparative Examples 2-5, changing the types of long-chain carboxylic acid ester polyoxyethylene, acrylic acid-modified silicone, and pentaerythritol stearate in the anti-fogging and anti-dripping agent reduced the mechanical properties of the prepared film. After prolonged exposure to heat and ultraviolet light, the water droplet angle significantly increased, resulting in reduced anti-dripping performance. This demonstrates that the anti-fogging and anti-dripping agent with specific components of this application can significantly improve the anti-dripping properties of the film.

[0061] Based on Example 1 and Comparative Example 6, and in conjunction with Table 3, it can be concluded that, compared to Example 1, Comparative Example 6 altered the formulation of metallocene low-density polyethylene, resulting in a significant reduction in the mechanical properties of the film. Furthermore, after prolonged exposure to heat and ultraviolet radiation, the water droplet angle increased significantly, leading to a decrease in anti-dripping performance.

[0062] Based on Example 1 and Comparative Example 7, and referring to Table 3, it can be concluded that the low-density polyethylene and modified toughening masterbatch of this application have a good synergistic effect, which can improve the mechanical properties of the film and enhance its anti-dripping properties. In Comparative Example 7, without the addition of modified toughening masterbatch, the mechanical properties of the resulting film are significantly reduced, and the water droplet angle also increases after long-term exposure to heat and ultraviolet light, resulting in a decrease in anti-dripping properties.

[0063] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A multi-layer co-extruded film for winter sheds in aquaculture, comprising an outer layer, a first adhesive layer, a middle layer, a second adhesive layer, and an inner layer, co-extruded and blown together, characterized in that, The inner layer is made from the following raw materials by weight percentage: Composite metallocene low-density polyethylene 63-71% Low-density polyethylene 10-20% Modified toughening masterbatch 5-10% Anti-fogging and anti-dripping agent 5-8% UV stabilizer 0.5-1% UV absorber 0.5-1% Antioxidant 0.2-0.5% Processing aids 2.5-5%; The composite metallocene low-density polyethylene is composed of metallocene low-density polyethylene A, metallocene low-density polyethylene B, and metallocene low-density polyethylene C in a weight ratio of (1.5-2.5):1:(0.2-0.35). The melt index of metallocene low-density polyethylene A is 0.2-0.8 g / 10min, the melt index of metallocene low-density polyethylene B is 1-1.7 g / 10min, and the melt index of metallocene low-density polyethylene C is 3.8-4.5 g / 10min. The modified toughening masterbatch contains ethylene propylene diene monomer (EPDM) rubber. The anti-fogging and anti-dripping agent is obtained by melt extrusion and granulation of styrene-octene-glycidyl methacrylate copolymer, vinyl elastomer, acrylic modified silicone, long-chain carboxylic acid ester polyoxyethylene, and pentaerythritol stearate.

2. The multi-layer co-extruded film for winter sheds in aquaculture according to claim 1, characterized in that, The anti-fogging and anti-dripping agent is prepared from the following raw materials by weight percentage: 60-70% styrene-octene-glycidyl methacrylate copolymer Vinyl elastomer 22-30% Acrylic modified silicone 2-4% Long-chain carboxylic acid esters, polyoxyethylene, 1.5-2.5% Pentaerythritol stearate 3-4.5%.

3. The multi-layer co-extruded film for winter sheds in aquaculture according to claim 2, characterized in that, The anti-fogging and anti-dripping agent is prepared by the following steps: First, styrene-octene-glycidyl methacrylate copolymer and long-chain carboxylic acid ester polyoxyethylene are mixed. Then, vinyl elastomer, acrylic modified silicone and pentaerythritol stearate are added and mixed. The mixture is then melt-extruded and granulated to obtain an anti-fogging and anti-dripping agent.

4. The multi-layer co-extruded film for winter sheds in aquaculture according to claim 3, characterized in that, The melt extrusion temperature is 160-200℃.

5. The multi-layer co-extruded film for winter sheds in aquaculture according to claim 1, characterized in that, The low-density polyethylene is composed of C4 linear low-density polyethylene and C6 linear low-density polyethylene in a weight ratio of 1:(2-4).

6. The multi-layer co-extruded film for winter sheds in aquaculture according to claim 1, characterized in that, The ultraviolet light stabilizer is a hindered amine stabilizer, and the ultraviolet light absorber is any one or a combination of benzotriazole absorbers, benzophenone absorbers, and triazine absorbers.

7. The multi-layer co-extruded film for winter sheds in aquaculture according to claim 1, characterized in that, The antioxidant is antioxidant 1010 and / or antioxidant 168.

8. The multilayer co-extruded film for winter sheds in aquaculture according to claim 1, characterized in that, The processing aids include an opening agent and a lubricant. The opening agent is one of fumed silica or organosilicon microspheres, and the lubricant is any one of polyethylene wax, calcium stearate, zinc stearate, or erucamide.

9. A method for preparing a multilayer co-extruded film for winter sheds in aquaculture as described in any one of claims 1-8, characterized in that, It is prepared by the following steps; The raw materials for each layer are melted separately, and then extruded, cooled, blown by an air ring, corona-treated, and wound up using a multi-layer co-extrusion blown film machine to produce a multi-layer co-extruded film for aquaculture.

10. The method for preparing a multilayer co-extruded film for winter sheds in aquaculture according to claim 9, characterized in that, The melt extrusion temperature is 150-200℃, the blow-up ratio is (2.5-3):1, and the draw ratio is (10-12):1.

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