A coated light-converting, high-insulation pinhole mulch film for use in greenhouses and its preparation method

Abstract

This invention belongs to the field of agricultural film technology, specifically relating to a coated high-insulation, light-converting, and light-converting pinhole mulch film for use in greenhouses and its preparation method. The coated high-insulation, light-converting, and light-converting pinhole mulch film for use in greenhouses according to this invention comprises, from the outside to the inside, a coating layer, an outer layer, a second outer layer, a middle layer, a second inner layer, and an inner layer. The outer and inner layers include: low-density metallocene polyethylene, high-density metallocene polyethylene, and a long-life masterbatch. The second outer and second inner layers include: a heat-insulating masterbatch with linear low-density powder as a carrier, a long-life masterbatch, low-density metallocene polyethylene, and linear low-density polyethylene. The middle layer includes: a heat-insulating masterbatch with ethylene-vinyl acetate copolymer as a carrier, a light-converting masterbatch, a long-life masterbatch, and ethylene-vinyl acetate copolymer. The coated high-insulation, light-converting, and light-converting pinhole mulch film for use in greenhouses provided by this invention has a drip-proof and anti-fogging effect that is synchronized with its service life, providing good heat insulation and good air permeability. This invention also provides its preparation method, which is reasonable, simple, and feasible.

Description

Technical Field

[0001] This invention belongs to the field of agricultural film technology, specifically relating to a coated light-converting high-insulation pinhole mulch film for use in greenhouses and its preparation method. Background Technology

[0002] Mulching technology is one of the core methods for increasing crop yields in modern agriculture. Traditional white plastic film, with its high light transmittance, effectively promotes the penetration of solar radiation through the film layer during the day, accumulating heat in the soil. Simultaneously, it reduces soil moisture evaporation through physical barriers (high moisture retention efficiency), playing a role in protecting roots and promoting growth during the seedling stage. However, it has the following key drawbacks:

[0003] (1) Poor heat retention at night: Due to the lack of effective blocking of far-infrared radiation in the 8-14μm band, more than 60% of the heat accumulated during the day is lost in the form of thermal radiation at night, resulting in a temperature fluctuation of more than 10℃ between day and night, which seriously inhibits the growth of seedlings.

[0004] (2) Lack of dripping function: When the temperature difference between the inside and outside of the membrane is ≥5℃, the density of water droplets condensed on the inner surface of the membrane can reach 200-500 drops / cm². These water droplets cause scattering loss of incident light due to the difference in refractive index, which reduces the actual light flux reaching the ground and significantly weakens the heat storage effect.

[0005] (3) Obstructed soil gas exchange: The closed environment leads to high CO2 concentration and low O2 concentration in the soil, which directly inhibits the aerobic respiration of the roots and causes the crop to lose nutrient absorption efficiency in the later stage.

[0006] To improve thermal insulation performance, functional mulch films with added hydrotalcite-based insulating agents have been introduced to the market. However, they face serious challenges: high cost, requiring a high amount of hydrotalcite to achieve effective infrared blocking; processing defects, as high addition levels can easily lead to particle agglomeration and the formation of large-diameter crystal points, affecting the film's light transmittance; and performance degradation, as the layered structure of hydrotalcite is easily peeled and decomposed under processing shear forces, resulting in a typically short thermal insulation lifespan.

[0007] CN112210144A discloses a special light-transmitting mulch film with anti-condensation properties, comprising Lanzhou Chemical 7042, high-pressure coating, EVA, and functional masterbatches (UV absorber, light-converting agent, heat-insulating agent, anti-drip agent, anti-fogging agent, ultramarine, paraffin wax, and zinc stearate). By incorporating UV absorbers, light-converting agents, and ultramarine, the mulch film avoids insufficient light transmittance during use. However, it is costly, has unstable light-converting performance, and cannot achieve both performance and other properties simultaneously. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a coated light-converting high heat-insulating pinhole mulch film for use in greenhouses. The anti-drip and anti-fogging effect has a duration that is synchronized with the service life. It has a high far-infrared blocking rate, excellent heat-insulating performance, and good air permeability. The present invention also provides its preparation method, which is reasonable, simple and feasible.

[0009] The coated light-converting high-insulation pinhole mulch film used in greenhouses according to the present invention consists of, from the outside to the inside, a coating layer, an outer layer, a second outer layer, a middle layer, a second inner layer, and an inner layer;

[0010] Both the outer and inner layers are made from the following raw material components in the following percentages by mass: 70-80% low-density metallocene polyethylene, 10-20% high-density metallocene polyethylene, and 5-10% long-life masterbatch; the low-density metallocene polyethylene used in the outer and inner layers is preferably 2010RA produced by Mobil Exxon.

[0011] Both the outer and inner layers are made from the following raw material components in the following mass percentages: 20-30% linear low-density powder as a carrier for thermal insulation masterbatch, 5-10% long-life masterbatch, 20-30% low-density metallocene polyethylene, and 30-40% linear low-density polyethylene; the low-density metallocene polyethylene used in the outer and inner layers is preferably 1018RA produced by Mobil Exxon.

[0012] The middle layer is made of the following raw material components in the following mass percentages: 30-40% thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier, 5-10% light conversion masterbatch, 5-10% long life masterbatch, and 40-50% ethylene-vinyl acetate copolymer.

[0013] The mass percentages of the outer layer, sub-outer layer, middle layer, sub-inner layer, and inner layer are as follows: outer layer 15%, sub-outer layer 20%, middle layer 30%, sub-inner layer 20%, and inner layer 15%. The coating amount is 0.15 g / m². 2 ~0.2g / m 2 .

[0014] The longevity masterbatch is made from the following raw material components by weight percentage: 5-8% light stabilizer, 1-2% composite antioxidant, and 90-94% linear low-density polyethylene.

[0015] The thermal insulation masterbatch with linear low-density powder as carrier is made of the following raw material components by mass percentage: 1-2% composite antioxidant, 10-20% kaolin, 10-20% polysiloxane, and 60-70% linear low-density polyethylene.

[0016] The thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier is made of the following raw material components by mass percentage: 1-2% composite antioxidant, 10-20% kaolin, 10-20% polysiloxane, and 60-70% ethylene-vinyl acetate copolymer.

[0017] The aforementioned light-converting masterbatch, by mass percentage, is made from the following raw material components: 1-2% composite antioxidant, 10-12% light-converting agent, and 86-89% ethylene-vinyl acetate copolymer.

[0018] The ethylene-vinyl acetate copolymer has a melt index of 0.65 g / 10 min and a density of 0.942 g / cm³ at 190°C and 2.16 kg. 3 The vinyl acetate (VA) content is 19%; preferably FL00119 produced by Mobil Exxon.

[0019] The low-density metallocene polyethylene has a melt index of 1 g / 10 min and a density of 0.918-0.920 g / cm³ at 190°C and 2.16 kg. 3 ;

[0020] The high-density metallocene polyethylene has a melt index of 0.2-1 g / 10 min and a density of 0.940-0.96 g / cm³ at 190℃ and 2.16 kg. 3 The preferred formulation is 4002MC manufactured by Mobil Exxon.

[0021] The linear low-density polyethylene described above has a melt index of 1.8-2 g / 10 min and a density of 0.918-0.923 g / cm³ at 190°C and 2.16 kg. 3 The preferred material is 35BN from Luqing Petrochemical Co., Ltd.

[0022] The kaolin has a mesh size of 10,000-15,000; the polysiloxane particle size is controlled at 1-3 μm; preferably 5HB produced by BASF and HL100 produced by Yongqi Materials Technology (Shanghai) Co., Ltd.

[0023] The composite antioxidant is obtained by compounding hindered phenolic antioxidants and phosphite antioxidants in a mass ratio of 1:1, preferably B225 produced by Tianjin Lianlong New Material Co., Ltd.

[0024] The light stabilizer is a hindered amine light stabilizer, preferably Tiangang®HS-944 produced by Beijing Tiangang Co., Ltd.

[0025] The light-converting agent is a rare earth ionic compound, preferably VTFR produced by Changsha Xiweier Co., Ltd. The light-converting agent used converts ultraviolet light around 350nm into near-infrared light of 690-800nm, thereby achieving a warming effect.

[0026] The aforementioned coated high-insulation heat-converting pinhole mulch film has a pinhole spacing of 3cm longitudinally and 2cm transversely; the pinhole diameter is approximately 0.5mm; the pin roller sleeve diameter is 205mm; the pin thickness is 2mm; and the pin height is 7.5mm.

[0027] The coating layer is obtained by applying a coating solution stock solution, which, by weight, comprises the following components: 20-30 parts aluminum sol, 15-20 parts silica sol, 10-15 parts surfactant, 5-10 parts organic acrylic resin, 3-5 parts defoamer, and 20-30 parts purified water. The coating layer is obtained by uniformly mixing the coating solution stock solution and purified water at a ratio of 1:10, subjecting it to corona treatment, slurry application, and drying. The coating solution stock solution is AG-189 manufactured by Takemoto Oils & Fats Co., Ltd. of Japan.

[0028] The preparation method of the coated light-converting high-insulation pinhole mulch film used in the greenhouse includes the following steps:

[0029] (1) Preparation of long-life masterbatch: using a mixer, linear low-density polyethylene, light stabilizer and composite antioxidant are added in sequence, and the mixture is stirred and sheared at high speed for 10-15 minutes. Forced feeding is used to feed the plasticized masterbatch into the screw of the extruder, and it is cooled and granulated to obtain long-life masterbatch.

[0030] (2) Preparation of thermal insulation masterbatch with linear low-density powder as carrier: The masterbatch is processed by internal mixer. Linear low-density polyethylene, kaolin, polysiloxane and composite antioxidant are added in sequence. The mixture is stirred and sheared at high speed for 10-15 minutes. The plasticized masterbatch is fed into the screw of the extruder, cooled and granulated to obtain thermal insulation masterbatch with linear low-density powder as carrier.

[0031] (3) Preparation of thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier: The masterbatch is processed by internal mixer. Ethylene-vinyl acetate copolymer, kaolin, polysiloxane and composite antioxidant are added in sequence. The mixture is stirred and sheared at high speed for 5-10 minutes. Forced feeding is used to feed the plasticized masterbatch into the screw of the extruder. The mixture is cooled and granulated to obtain thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier.

[0032] (4) Preparation of brightening masterbatch: using a mixer, ethylene-vinyl acetate copolymer, brightening agent and composite antioxidant are added in sequence, and the mixture is stirred and sheared at high speed for 5-10 minutes. Forced feeding is used to feed the plasticized masterbatch into the screw of the extruder, and it is cooled and granulated to obtain brightening masterbatch.

[0033] (5) Preparation of coated light-converting high heat-insulating pinhole mulch for use in greenhouses: The raw material components of the outer layer, the second outer layer, the middle layer, the second inner layer and the inner layer are mixed evenly, and the coated multifunctional high heat-insulating pinhole mulch for use in greenhouses is obtained by blowing, cooling, corona treatment, slurry coating, impregnation, drying, punching and film stacking.

[0034] The processing temperature for preparing longevity masterbatch is 140-160℃.

[0035] The processing temperature for preparing thermal insulation masterbatch with linear low-density powder as carrier, thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier, and light conversion masterbatch is 130-150℃.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] (1) The present invention uses a coating process, and the anti-fogging and anti-dripping effect can be synchronized with the lifespan, and can reach an anti-fogging and anti-dripping effect of at least 6 months.

[0038] (2) The present invention uses a five-layer co-extrusion equipment, and the formula design is more reasonable and flexible. The outer and inner layers use high-density metallocene polyethylene, which improves the overall puncture resistance of the film, makes the pinholes more uniform, reduces the deformation during punching, and ensures the mechanical properties of the entire mulch film after punching. The middle layer uses ethylene-vinyl acetate copolymer compounded with a new type of thermal insulation masterbatch with ethylene-vinyl acetate as the carrier, which greatly improves the overall thermal insulation performance of the mulch film. The second outer and second inner layers use high-strength metallocene compounded with a new type of thermal insulation masterbatch with linear low density as the carrier, which can ensure the overall physical properties of the film and improve the overall thermal insulation performance of the mulch film. The use of five-layer equipment realizes the diversification of the functions of the mulch film.

[0039] (3) The present invention uses kaolin and polysiloxane as a heat preservation agent. Compared with traditional hydrotalcite, it has low haze, which gives the mulch film a high far-infrared blocking rate, thereby achieving excellent heat preservation performance and reducing costs.

[0040] (4) The present invention uses VTFR produced by Changsha Xiweier Co., Ltd. as a light conversion agent. Compared with traditional light conversion agents, it can convert ultraviolet light into near-infrared light with higher energy than visible light, thereby achieving the effect of increasing ground temperature.

[0041] (5) The pinholes made in this invention not only satisfy the functions of air permeability and water permeability, but also have little impact on the mechanical properties of the film, and can meet the requirements for long-term use in the greenhouse. Detailed Implementation

[0042] The present invention will be further described below with reference to specific embodiments.

[0043] The raw materials used in the following examples and comparative examples are:

[0044] The outermost and innermost layers use low-density metallocene polyethylene: 1018RA manufactured by Mobil Exxon, which has a melt index of 1 g / 10 min and a density of 0.918 g / cm³ at 190°C and 2.16 kg. 3 .

[0045] The outer and inner layers use low-density metallocene polyethylene: 2010RA manufactured by Mobil Exxon, which has a melt index of 1 g / 10 min and a density of 0.920 g / cm³ at 190°C and 2.16 kg. 3 .

[0046] The linear low-density polyethylene used in the outer and inner layers is 35B from Luqing Petrochemical Co., Ltd., with a melt index of 2 g / 10 min and a density of 0.92 g / cm³ under conditions of 190℃ and 2.16 kg. 3 ;

[0047] The linear low-density polyethylene used in the thermal insulation masterbatch, which is based on long-life masterbatch and linear low-density powder as a carrier, is DGM-1820 from Zhongyuan Petrochemical Company in Puyang, Henan Province. It has a melt flow index of 2 g / 10 min and a density of 0.923 g / cm³ under conditions of 190℃ and 2.16 kg. 3

[0048] In this embodiment, the high-density metallocene polyethylene used in the outer and inner layers is Mobil Exxon's 4002MC, which has a melt index of 0.25 g / 10 min and a density of 0.940 g / cm³ at 190°C and 2.16 kg. 3 .

[0049] The high-density linear polyethylene used in the comparative example was 7000F from Mehr Petrochemical Company of Iran, with a melt index of 0.03-0.04 g / 10 min and a density of 0.950-0.954 g / cm³ under 2.16 kg conditions. 3 .

[0050] In the embodiments, the kaolin used as the raw material for the thermal insulation masterbatch with linear low-density powder as the carrier and the kaolin used as the carrier with ethylene-vinyl acetate copolymer are both kaolin produced by BASF, with the model number 5HB; the polysiloxane used as the raw material is produced by Yongqi Materials Technology (Shanghai) Co., Ltd., with the model number HL100.

[0051] The heat-insulating agent used in the comparative example was HT-V manufactured by Sakai Chemical Industry Co., Ltd. of Japan.

[0052] Composite antioxidant: B225 produced by Tianjin Lianlong New Material Co., Ltd. (This raw material is used in long-life masterbatch, thermal insulation masterbatch with linear low-density powder as carrier, thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier, and light conversion masterbatch).

[0053] In the examples, the light conversion agent used in the light conversion masterbatch was VTFR produced by Changsha Xiweier Co., Ltd.

[0054] The ethylene-vinyl acetate copolymer used in the examples and comparative examples was FL00119 manufactured by Mobil Exxon, with a melt index of 0.65 g / 10 min and a density of 0.942 g / cm³ at 2.16 kg. 3 The vinyl acetate (VA) content is 19%. (This raw material is used in the light conversion masterbatch, the thermal insulation masterbatch with ethylene-vinyl acetate copolymer as the carrier, and the middle layer.)

[0055] The light stabilizers used are all produced by Beijing Tiangang Co., Ltd., namely Tiangang®HS-944.

[0056] The coating solution stock solution is AG-189 produced by Takemoto Oil Co., Ltd. of Japan. The coating solution stock solution is mixed with purified water at a ratio of 1:10 and then coated. The coating is measured in parts by weight.

[0057] Example 1

[0058] The preparation method of the coated light-converting high-insulation pinhole mulch film used in the greenhouse includes the following steps:

[0059] (1) Preparation of masterbatch for each layer:

[0060] The longevity masterbatch is made from the following raw material components by weight percentage: 5% light stabilizer, 1% composite antioxidant, and 94% linear low-density polyethylene.

[0061] The thermal insulation masterbatch with linear low-density powder as carrier is made of the following raw material components by mass percentage: 1% composite antioxidant, 20% kaolin, 10% polysiloxane, and 69% linear low-density polyethylene.

[0062] The thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier is made of the following raw material components by mass percentage: 1% composite antioxidant, 20% kaolin, 10% polysiloxane, and 69% ethylene-vinyl acetate copolymer.

[0063] The aforementioned light-converting masterbatch, by mass percentage, is made from the following raw material components: 1% composite antioxidant, 10% light-converting agent, and 89% ethylene-vinyl acetate copolymer;

[0064] (2) Preparation of various masterbatches:

[0065] Preparation of long-life masterbatch: The masterbatch is processed in an internal mixer at 150°C. Linear low-density polyethylene, light stabilizer, and composite antioxidant are added in sequence. The mixture is stirred and sheared at high speed for 10 minutes. Forced feeding is used to feed the plasticized masterbatch into the screw of the extruder. The masterbatch is cooled and granulated to obtain the long-life masterbatch.

[0066] Preparation of thermal insulation masterbatch with linear low-density powder as carrier: The masterbatch is processed in an internal mixer at 150°C. Linear low-density polyethylene, kaolin, polysiloxane and composite antioxidant are added in sequence. The mixture is stirred and sheared at high speed for 10 minutes. Forced feeding is used to feed the plasticized masterbatch into the screw of an extruder. The mixture is cooled and granulated to obtain thermal insulation masterbatch with linear low-density powder as carrier.

[0067] Preparation of thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier: Processed in a 130°C internal mixer, ethylene-vinyl acetate copolymer, kaolin, polysiloxane, and composite antioxidant are added in sequence, and the mixture is stirred and sheared at high speed for 10 minutes. Forced feeding is used to feed the plasticized masterbatch into the screw of an extruder, where it is cooled and granulated to obtain thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier.

[0068] Preparation of brightening masterbatch: Processed in an internal mixer at 130℃, ethylene-vinyl acetate copolymer, brightening agent, and composite antioxidant were added in sequence, and the mixture was stirred and sheared at high speed for 10 minutes. Forced feeding was used to feed the plasticized masterbatch into the screw of an extruder, and it was cooled and granulated to obtain brightening masterbatch.

[0069] (3) Prepare the raw materials for each layer:

[0070] Both the outer and inner layers are made from the following raw material components, in percentage by mass: 70% low-density metallocene polyethylene, 20% high-density metallocene polyethylene, and 10% long-life masterbatch.

[0071] Both the outer and inner layers are made from the following raw material components in the following mass percentages: 30% linear low-density powder as a carrier for thermal insulation masterbatch, 10% long-life masterbatch, 30% low-density metallocene polyethylene, and 30% linear low-density polyethylene.

[0072] The middle layer is made of the following raw material components in the following mass percentages: 40% thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier, 10% brightening masterbatch, 10% long life masterbatch, and 40% ethylene-vinyl acetate copolymer.

[0073] (4) Preparation of coated light-converting high-insulation pinhole mulch film for use in greenhouses:

[0074] The raw material components of the outer layer, second outer layer, middle layer, second inner layer, and inner layer are uniformly mixed separately. The thickness percentages of each layer are as follows: outer layer 15%, second outer layer 20%, middle layer 30%, second inner layer 20%, and inner layer 15%. Each layer is plasticized and sheared using an extruder, with a film thickness of 0.015 mm, resulting in a five-layer co-extruded composite mulch film. After corona treatment, an online coating solution is applied at a coating amount of 0.18 g / m². 2 After drying and shaping, a coated multifunctional high-insulation pinhole mulch film for use in greenhouses is obtained.

[0075] Example 2

[0076] The preparation method of the coated light-converting high-insulation pinhole mulch film used in the greenhouse includes the following steps:

[0077] (1) Preparation of masterbatch for each layer:

[0078] The longevity masterbatch is made from the following raw material components by weight percentage: 5% light stabilizer, 1% composite antioxidant, and 94% linear low-density polyethylene.

[0079] The thermal insulation masterbatch with linear low-density powder as carrier is made of the following raw material components by mass percentage: 1% composite antioxidant, 15% kaolin, 15% polysiloxane, and 69% linear low-density polyethylene.

[0080] The thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier is made of the following raw material components by mass percentage: 1% composite antioxidant, 15% kaolin, 15% polysiloxane, and 69% ethylene-vinyl acetate copolymer.

[0081] The aforementioned light-converting masterbatch, by mass percentage, is made from the following raw material components: 1% composite antioxidant, 11% light-converting agent, and 88% ethylene-vinyl acetate copolymer;

[0082] (2) Preparation of various masterbatches:

[0083] Preparation of long-life masterbatch: The masterbatch is processed in an internal mixer at 140°C. Linear low-density polyethylene, light stabilizer and composite antioxidant are added in sequence. The mixture is stirred and sheared at high speed for 15 minutes. Forced feeding is used to feed the plasticized masterbatch into the screw of the extruder. The masterbatch is cooled and granulated to obtain long-life masterbatch.

[0084] Preparation of thermal insulation masterbatch with linear low-density powder as carrier: The masterbatch is processed in an internal mixer at 130°C. Linear low-density polyethylene, kaolin, polysiloxane and composite antioxidant are added in sequence. The mixture is stirred and sheared at high speed for 15 minutes. Forced feeding is used to feed the plasticized masterbatch into the screw of an extruder. The mixture is cooled and granulated to obtain thermal insulation masterbatch with linear low-density powder as carrier.

[0085] Preparation of thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier: Processed in a 130°C internal mixer, ethylene-vinyl acetate copolymer, kaolin, polysiloxane, and composite antioxidant are added in sequence, and the mixture is stirred and sheared at high speed for 10 minutes. Forced feeding is used to feed the plasticized masterbatch into the screw of an extruder, where it is cooled and granulated to obtain thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier.

[0086] Preparation of brightening masterbatch: Processed in an internal mixer at 130℃, ethylene-vinyl acetate copolymer, brightening agent, and composite antioxidant were added in sequence, and the mixture was stirred and sheared at high speed for 10 minutes. Forced feeding was used to feed the plasticized masterbatch into the screw of an extruder, and it was cooled and granulated to obtain brightening masterbatch.

[0087] (3) Prepare the raw materials for each layer:

[0088] Both the outer and inner layers are made from the following raw material components, in percentage by mass: 70% low-density metallocene polyethylene, 20% high-density metallocene polyethylene, and 10% long-life masterbatch.

[0089] Both the outer and inner layers are made from the following raw material components in the following mass percentages: 30% linear low-density powder as a carrier for thermal insulation masterbatch, 10% long-life masterbatch, 30% low-density metallocene polyethylene, and 30% linear low-density polyethylene.

[0090] The middle layer is made of the following raw material components in the following mass percentages: 40% thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier, 10% brightening masterbatch, 10% long life masterbatch, and 40% ethylene-vinyl acetate copolymer.

[0091] (4) Preparation of coated light-converting high-insulation pinhole mulch film for use in greenhouses:

[0092] The raw material components of the outer layer, second outer layer, middle layer, second inner layer, and inner layer are uniformly mixed separately. The thickness percentages of each layer are as follows: outer layer 15%, second outer layer 20%, middle layer 30%, second inner layer 20%, and inner layer 15%. Each layer is plasticized and sheared using an extruder, with a film thickness of 0.015 mm, resulting in a five-layer co-extruded composite mulch film. After corona treatment, an online coating solution is applied at a coating amount of 0.18 g / m². 2 After drying and shaping, a coated multifunctional high-insulation pinhole mulch film for use in greenhouses is obtained.

[0093] Example 3

[0094] The preparation method of the coated light-converting high-insulation pinhole mulch film used in the greenhouse includes the following steps:

[0095] (1) Preparation of masterbatch for each layer:

[0096] The longevity masterbatch is made from the following raw material components by weight percentage: 5% light stabilizer, 1% composite antioxidant, and 94% linear low-density polyethylene.

[0097] The thermal insulation masterbatch with linear low-density powder as carrier is made of the following raw material components by mass percentage: 2% composite antioxidant, 10% kaolin, 20% polysiloxane, and 68% linear low-density polyethylene.

[0098] The thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier is made of the following raw material components by mass percentage: 2% composite antioxidant, 10% kaolin, 20% polysiloxane, and 68% ethylene-vinyl acetate copolymer.

[0099] The aforementioned light-converting masterbatch, by mass percentage, is made from the following raw material components: 2% composite antioxidant, 12% light-converting agent, and 86% ethylene-vinyl acetate copolymer;

[0100] (2) Preparation of various masterbatches:

[0101] Preparation of long-life masterbatch: The masterbatch is processed in an internal mixer at 160°C. Linear low-density polyethylene, light stabilizer and composite antioxidant are added in sequence. The mixture is stirred and sheared at high speed for 10 minutes. Forced feeding is used to feed the plasticized masterbatch into the screw of the extruder. The mixture is cooled and granulated to obtain long-life masterbatch.

[0102] Preparation of thermal insulation masterbatch with linear low-density powder as carrier: The masterbatch is processed in an internal mixer at 150°C. Linear low-density polyethylene, kaolin, polysiloxane and composite antioxidant are added in sequence. The mixture is stirred and sheared at high speed for 10 minutes. Forced feeding is used to feed the plasticized masterbatch into the screw of an extruder. The mixture is cooled and granulated to obtain thermal insulation masterbatch with linear low-density powder as carrier.

[0103] Preparation of thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier: Processed in an internal mixer at 150℃, ethylene-vinyl acetate copolymer, kaolin, polysiloxane, and composite antioxidant are added in sequence, and the mixture is stirred and sheared at high speed for 5-10 minutes. Forced feeding is used to feed the plasticized masterbatch into the screw of an extruder, where it is cooled and granulated to obtain thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier.

[0104] Preparation of brightening masterbatch: Processed in an internal mixer at 150°C, ethylene-vinyl acetate copolymer, brightening agent, and composite antioxidant were added in sequence, and the mixture was stirred and sheared at high speed for 5 minutes. Forced feeding was used to feed the plasticized masterbatch into the screw of an extruder, and it was cooled and granulated to obtain brightening masterbatch.

[0105] (3) Prepare the raw materials for each layer:

[0106] Both the outer and inner layers are made from the following raw material components, in percentage by mass: 70% low-density metallocene polyethylene, 20% high-density metallocene polyethylene, and 10% long-life masterbatch.

[0107] Both the outer and inner layers are made from the following raw material components in the following mass percentages: 30% linear low-density powder as a carrier for thermal insulation masterbatch, 10% long-life masterbatch, 30% low-density metallocene polyethylene, and 30% linear low-density polyethylene.

[0108] The middle layer is made of the following raw material components in the following mass percentages: 40% thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier, 10% brightening masterbatch, 10% long life masterbatch, and 40% ethylene-vinyl acetate copolymer.

[0109] (4) Preparation of coated light-converting high-insulation pinhole mulch film for use in greenhouses:

[0110] The raw material components of the outer layer, second outer layer, middle layer, second inner layer, and inner layer are uniformly mixed separately. The thickness percentages of each layer are as follows: outer layer 15%, second outer layer 20%, middle layer 30%, second inner layer 20%, and inner layer 15%. Each layer is plasticized and sheared using an extruder, with a film thickness of 0.015 mm, resulting in a five-layer co-extruded composite mulch film. After corona treatment, an online coating solution is applied at a coating amount of 0.18 g / m². 2 After drying and shaping, a coated multifunctional high-insulation pinhole mulch film for use in greenhouses is obtained.

[0111] Comparative Example 1

[0112] The only difference between this comparative example and Example 1 is that the sum of kaolin and polysiloxane in the insulation masterbatch of the middle layer, the innermost layer and the outermost layer is replaced with pure water talc insulation agent.

[0113] Comparative Example 2

[0114] The only difference between this comparative example and Example 1 is that the kaolin in the insulation masterbatch of the middle layer, the innermost layer and the outermost layer is removed and replaced with polysiloxane in equal amounts.

[0115] Comparative Example 3

[0116] The only difference between this comparative example and Example 1 is that the polysiloxane in the insulation masterbatch of the middle layer, the innermost layer and the outermost layer is removed and replaced with an equal amount of kaolin.

[0117] Comparative Example 4

[0118] The only difference between this comparative example and Example 1 is that the middle layer of thermal insulation masterbatch is removed and replaced with an equal amount of ethylene-vinyl acetate copolymer.

[0119] Comparative Example 5

[0120] The only difference between this comparative example and Example 1 is that the high-density metallocene polyethylene in the inner and outer layers is replaced with high-density linear polyethylene.

[0121] Comparative Example 6

[0122] The only difference between this comparative example and Example 1 is that the high-density metallocene polyethylene in both the inner and outer layers is replaced with low-density metallocene polyethylene.

[0123] Comparative Example 7

[0124] The only difference between this comparative example and Example 1 is that the intermediate light-converting masterbatch is removed and replaced with an equal amount of ethylene-vinyl acetate copolymer.

[0125] The performance of the mulch films prepared in each embodiment and comparative example was compared through performance testing. The total thickness of the mulch films was uniformly 0.015 mm, and the thickness percentage of each layer was as follows: outer layer 15%, second outer layer 20%, middle layer 30%, second inner layer 20%, and inner layer 15%. The testing methods are as follows:

[0126] (1) Thermal insulation: The thermal insulation performance was determined by testing the transmittance of the mulch film in the wavelength range of 7-13μm using an infrared spectrometer. The higher the transmittance, the worse the thermal insulation effect. The test results are shown in Table 1.

[0127] (2) Mechanical properties: Tensile strength and elongation at break were tested in accordance with the national standard GB13735-2017 for agricultural films. The test results are shown in Table 1.

[0128] (3) Optical performance: The transmittance and haze value were tested in accordance with GB / T 2410-2008 standard, and the test results are shown in Table 1;

[0129] (4) Drilling efficiency: The number of holes drilled per square meter is divided by the total number of holes to calculate the result. The higher the result value, the higher the drilling efficiency. The test results are shown in Table 1.

[0130] (5) Ground temperature test of the area covered by mulch film: The blown samples of the above three examples and seven comparative examples were laid on the open ground. The ground temperature covered by each sample was tested before 7 am every day in winter (before sunrise). The test was conducted for 3 consecutive days. Five groups were tested each time and the average value was taken. The test results are shown in Table 2.

[0131] (6) Test of drip retention period: The test was conducted in accordance with the standard QB / T4475-2013. The water bath temperature was (60±1)℃ and the water bath was continuously used for 30 days. The white dew drop area ratio was not greater than 30% or the transparent drop area was not greater than 50%. The results after 30 days of testing are shown in Table 3.

[0132] Table 1 Test Results

[0133]

[0134] Table 2. Ground temperature test results in areas covered with mulch film.

[0135]

[0136] Table 3 Results of the test on the duration of dripping effect

[0137]

[0138] As shown in Table 1, the thermal insulation performance of Examples 1, 2, and 3 improved with increasing polysiloxane content in the thermal insulation masterbatch. Furthermore, according to the test results in Table 2, the ground temperature also increased with increasing polysiloxane content. However, when all the thermal insulation agents in the masterbatch were replaced with polysiloxane (i.e., Comparative Example 2), although the thermal insulation performance reached its optimal level, the ground temperature, as shown in Table 2, was even lower than in Example 1. The reason for this is that excessive addition of polysiloxane significantly increases haze, which greatly reduces sunlight intensity during the day, resulting in slower ground temperature accumulation and consequently lower ground temperature.

[0139] As can be seen from Table 1, when the thermal insulation agent was completely replaced with hydrotalcite, that is, Comparative Example 1, the thermal insulation performance was significantly reduced compared with Examples 1, 2, 3 and Comparative Examples 2, 3. This indicates that the thermal insulation performance of hydrotalcite is worse than that of kaolin and polysiloxane. The temperature test results in Table 2 also show that the ground temperature covered by Comparative Example 1 was the lowest compared with Examples 1, 2, 3 and Comparative Examples 2, 3.

[0140] As can be seen from Table 1, in Comparative Example 5, after replacing the high-density metallocene polyethylene in the outer and inner layers with high-density linear polyethylene, although the perforation rate of the film was not affected, the longitudinal and transverse tear strength of the film was reduced, and it failed the test according to the national standard GB13735-2017 for agricultural films.

[0141] As can be seen from Table 1, in Comparative Example 6, after replacing the high-density polyethylene of the outer and inner layers with low-density metallocene polyethylene, although the mechanical properties of the film were significantly improved, the perforation rate per unit square meter was low due to the excessively high strength of the film, which could not meet the actual use effect.

[0142] As can be seen from Tables 1 and 2, after removing the light-converting masterbatch, the far-infrared transmittance test results increased slightly, indicating that the heat insulation performance decreased slightly, but the impact was not significant. However, when the actual ground temperature was measured, there was a certain difference in temperature compared with other examples and comparative examples, indicating that although the light-converting agent did not have a significant impact on the heat insulation effect of the film, it had a significant impact on the ground temperature increase effect and played a very crucial role.

[0143] As can be seen from Table 3, no white dewdrops appeared in any of the embodiments and comparative examples during the test, and the area ratio of non-flowing transparent droplets did not exceed 40%. The coating effect met the test standard for coating film with a one-year service life, proving that the dripping effect of the present invention is at least 6 months.

[0144] Through a series of comparative tests and data analysis, this invention achieves a balance of heat preservation performance, mechanical properties, anti-fogging and anti-dripping properties, and perforation performance through the technical advantages of its formula. The overall performance is excellent, which plays a good auxiliary role in winter greenhouse planting and improves the ability of crop roots to resist the risk of low temperature.

Claims

1. A coated light-converting, high-insulation pinhole mulch film for use in greenhouses, characterized in that: From the outside to the inside, the layers are: coating layer, outer layer, sub-outer layer, middle layer, sub-inner layer, and inner layer. Both the outer and inner layers are made from the following raw material components, in percentage by mass: 70-80% low-density metallocene polyethylene, 10-20% high-density metallocene polyethylene, and 5-10% long-life masterbatch. Both the outer and inner layers are made from the following raw material components in the following mass percentages: 20-30% linear low-density powder as a carrier for thermal insulation masterbatch, 5-10% long-life masterbatch, 20-30% low-density metallocene polyethylene, and 30-40% linear low-density polyethylene. The middle layer is made of the following raw material components in the following mass percentages: 30-40% thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier, 5-10% light conversion masterbatch, 5-10% long-life masterbatch, and 40-50% ethylene-vinyl acetate copolymer; the long-life masterbatch is made of the following raw material components in the following mass percentages: 5-8% light stabilizer, 1-2% composite antioxidant, and 90-94% linear low-density polyethylene; The coating layer is obtained by coating with the original coating liquid, which includes the following components by weight: 20-30 parts aluminum sol, 15-20 parts silica sol, 10-15 parts surfactant, 5-10 parts organic acrylic resin, 3-5 parts defoamer, and 20-30 parts purified water. The thermal insulation masterbatch with linear low-density powder as carrier is made of the following raw material components by mass percentage: 1-2% composite antioxidant, 10-20% kaolin, 10-20% polysiloxane, and 60-70% linear low-density polyethylene. The thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier is made of the following raw material components by mass percentage: 1-2% composite antioxidant, 10-20% kaolin, 10-20% polysiloxane, and 60-70% ethylene-vinyl acetate copolymer. The aforementioned light-converting masterbatch, by mass percentage, is made from the following raw material components: 1-2% composite antioxidant, 10-12% light-converting agent, and 86-89% ethylene-vinyl acetate copolymer; The light-converting agent is VTFR.

2. The coated light-converting, high-insulation pinhole mulch film used in greenhouses according to claim 1, characterized in that: The mass percentages of the outer layer, sub-outer layer, middle layer, sub-inner layer, and inner layer are as follows: outer layer 15%, sub-outer layer 20%, middle layer 30%, sub-inner layer 20%, and inner layer 15%; the coating amount is 0.15 g / m³. 2 ~0.2g / m 2 .

3. The coated light-converting, high-insulation pinhole mulch film used in greenhouses according to claim 1, characterized in that: The ethylene-vinyl acetate copolymer has a melt index of 0.65 g / 10 min and a density of 0.942 g / cm³ at 190°C and 2.16 kg. 3 Vinyl acetate content 17-19 wt.%; The low-density metallocene polyethylene has a melt index of 1 g / 10 min and a density of 0.918-0.920 g / cm³ at 190°C and 2.16 kg. 3 ; The high-density metallocene polyethylene has a melt index of 0.2-1 g / 10 min and a density of 0.940-0.96 g / cm³ at 190℃ and 2.16 kg. 3 ; The linear low-density polyethylene described above has a melt index of 1.8-2 g / 10 min and a density of 0.918-0.923 g / cm³ at 190°C and 2.16 kg. 3 .

4. The coated light-converting, high-insulation pinhole mulch film used in greenhouses according to claim 1, characterized in that: The kaolin has a mesh size of 10,000-15,000; the polysiloxane particle size is controlled at 1-3 μm.

5. The coated light-converting, high-insulation pinhole mulch film for use in greenhouses according to claim 1, characterized in that: The composite antioxidant is obtained by compounding hindered phenolic antioxidants and phosphite antioxidants in a mass ratio of 1:1; the light stabilizer is a hindered amine light stabilizer.

6. The coated light-converting, high-insulation pinhole mulch film used in greenhouses according to claim 1, characterized in that: The aforementioned coated high-insulation heat-converting pinhole mulch film has a pinhole spacing of 3cm longitudinally and 2cm transversely; a pinhole diameter of 0.5mm; a pin roller sleeve diameter of 205mm; a pin diameter of 2mm; and a pin height of 7.5mm.

7. A method for preparing a coated light-converting, high-insulation pinhole mulch film for use in greenhouses as described in any one of claims 1-6, characterized in that: Includes the following steps: (1) Preparation of long-life masterbatch: using a mixer, linear low-density polyethylene, light stabilizer and composite antioxidant are added in sequence, and the mixture is stirred and sheared at high speed for 10-15 minutes. Forced feeding is used to feed the plasticized masterbatch into the screw of the extruder, and it is cooled and granulated to obtain long-life masterbatch. (2) Preparation of thermal insulation masterbatch with linear low-density powder as carrier: The masterbatch is processed by internal mixer. Linear low-density polyethylene, kaolin, polysiloxane and composite antioxidant are added in sequence. The mixture is stirred and sheared at high speed for 10-15 minutes. The plasticized masterbatch is fed into the screw of the extruder, cooled and granulated to obtain thermal insulation masterbatch with linear low-density powder as carrier. (3) Preparation of thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier: The masterbatch is processed by internal mixer. Ethylene-vinyl acetate copolymer, kaolin, polysiloxane and composite antioxidant are added in sequence. The mixture is stirred and sheared at high speed for 5-10 minutes. Forced feeding is used to feed the plasticized masterbatch into the screw of the extruder. The mixture is cooled and granulated to obtain thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier. (4) Preparation of brightening masterbatch: using a mixer, ethylene-vinyl acetate copolymer, brightening agent and composite antioxidant are added in sequence, and the mixture is stirred and sheared at high speed for 5-10 minutes. Forced feeding is used to feed the plasticized masterbatch into the screw of the extruder, and it is cooled and granulated to obtain brightening masterbatch. (5) Preparation of coated light-converting high heat-insulating pinhole mulch for use in greenhouses: The raw material components of the outer layer, the second outer layer, the middle layer, the second inner layer and the inner layer are mixed evenly, and the coated multifunctional high heat-insulating pinhole mulch for use in greenhouses is obtained by blow molding, cooling, corona treatment, slurry coating, impregnation, drying, punching and film stacking.

8. The method for preparing the coated light-converting high-insulation pinhole mulch film for use in greenhouses according to claim 7, characterized in that: The processing temperature for preparing longevity masterbatch is 140-160℃.

9. The method for preparing the coated light-converting high-insulation pinhole mulch film for use in greenhouses according to claim 7, characterized in that: The processing temperature for preparing thermal insulation masterbatch with linear low-density powder as carrier, thermal insulation masterbatch with ethylene-vinyl acetate copolymer as carrier, and light conversion masterbatch is 130-150℃.

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