Polyethylene material as well as preparation method and application thereof

Abstract

The invention provides a polyethylene material preparation method, which comprises: adding a hindered phenol antioxidant to a mixture of an allyl organic compound, an organic peroxide and 3-mercaptopropionate, and mixing to obtain a suspension; uniformly mixing paraffin, stearic acid and high-density polyethylene to obtain polyethylene master batches; under the stirring condition, mixing the turbid liquid, a first organic solvent and the polyethylene master batch for reaction, and extruding to obtain mixed master batch; and uniformly mixing the mixed master batch and rhodamine in a second organic solvent to obtain the polyethylene material. The polyethylene material can still store energy and convert light for a long time in rainy days or in the weather with the humidity larger than or equal to 80%, and then the problem that growth of plants is stagnated due to the fact that the plants cannot be supplemented with light in cloudy and rainy days and at night is solved.

Description

Technical Field

[0001] This invention relates to the field of polyethylene materials, specifically to a polyethylene material, its preparation method, and its applications. Background Technology

[0002] Existing agricultural plastic films are divided into three main categories: the first is ordinary agricultural plastic film; the second is functional agricultural plastic film, including functions such as anti-aging, anti-fogging, heat insulation, and dust prevention; and the third is control-functional agricultural plastic film, including spectral selection, spectral conversion, and functional control. Among these, the novel light-converting film with spectral conversion, based on the principles of photoecology, converts sunlight energy into a portion of the agricultural film to extend the light exposure time for plants. This technology has become an important direction for the functionalization of agricultural films to meet the needs of modern agriculture and artificial greenhouses.

[0003] Novel light-converting films for spectral conversion include the addition of additives, such as rare earth materials or organic fluorescent materials, and the design and production of multilayer composite films, such as PE / EVA / PE or PE / PVC / PE. However, existing high-efficiency plastic agricultural films have some drawbacks, such as the poor photostability of organic fluorescent materials, the high production cost of rare earth organic coordination compounds, and low spectral conversion efficiency.

[0004] To address the aforementioned issues, existing technologies disclose rare-earth silicate-based composite red luminescent films that enhance the intensity of red light by converting ultraviolet and green light into red light. This technology not only reduces energy consumption but also helps increase crop growth efficiency. Chinese patent document CN1072945A discloses an agricultural wavelength conversion material that reduces near-ultraviolet and green light and increases blue and red light in sunlight transmitted through the film. Chinese patent document CN109734940A discloses a method for preparing a rare-earth silicate-based composite red luminescent greenhouse film. The method includes: preparing rare-earth magnesium strontium silicate luminescent material using a high-temperature solid-state method; weighing a light-converting agent and the rare-earth magnesium strontium silicate luminescent material and placing them in an ethanol solution, stirring to dissolve, and heating in a water bath to form a mixed solution of rare-earth magnesium strontium silicate and light-converting agent; adding an aluminate coupling agent to the mixed solution of rare-earth magnesium strontium silicate and light-converting agent, stirring until a suspension is formed, and then adding a silane coupling agent to obtain the silicate-based composite red luminescent material; grinding to obtain silicate-based composite red luminescent powder, and then incorporating it into PVC resin to form a greenhouse film. This light-converting greenhouse film converts ultraviolet and green light into red light, increasing the intensity of red light irradiation, and consumes no energy compared to supplemental lighting from a light source. Chinese patent document CN104479437A discloses a method for preparing a superhydrophobic self-luminescent coating. First, a polymer monomer, crosslinking agent, initiator, nanoparticles, and a long-afterglow luminescent material are uniformly mixed to obtain a mixture. Then, this mixture is uniformly coated onto the surface of a substrate and polymerized to obtain a superhydrophobic self-luminescent coating. This superhydrophobic self-luminescent coating expands the application range of long-afterglow luminescent materials while solving the problems of water decomposition or reduced luminescence intensity. However, for materials with large surface areas, such as greenhouse films, this coating method leads to high consumption and uneven application.

[0005] The Changchun Institute of Physics, Chinese Academy of Sciences, and other institutions have developed a light-energy conversion film that promotes crop photosynthesis by utilizing the "antenna effect" of rare-earth-organic coordination compounds. This film emits strong red light, absorbs 365nm ultraviolet light, and emits 612nm red light. The Department of Chemistry at Shanghai Normal University has created a UTR rare-earth complex agricultural light-converting film by adding a fluorescent rare-earth complex to the production process of ordinary agricultural films. Under irradiation across all wavelengths of ultraviolet-visible-infrared light, the new film exhibits a higher quantum intensity transmittance than ordinary agricultural films, especially in the 230–860nm range, where the overall increase in transmittance is 4%–18%, demonstrating a better ability to utilize the photothermal effect under sunlight.

[0006] In summary, the current development trend of agricultural plastic films is towards greater efficiency and environmental friendliness to meet the needs of modern agriculture. Red and blue light have the greatest impact on plant growth, especially red light, which can significantly accelerate plant growth and development. To improve the quality and yield of crops, modern greenhouse crops use artificial lighting. This method mainly includes increasing light intensity, extending the duration of illumination, and supplementing with different light qualities. Currently, increasing light intensity and duration mainly relies on light sources such as fluorescent lamps, incandescent lamps, and high-pressure mercury lamps, but these suffer from low luminous efficiency and high energy consumption. However, in recent years, new light sources such as LEDs have emerged, which have low energy consumption and high efficiency, but their price is relatively high.

[0007] Therefore, there is an urgent need for a greenhouse film material that can still store and convert light into energy for a long time in rainy weather or when the humidity is greater than 80% to solve the problem of plants not receiving light supplementation during cloudy and rainy days and at night, which leads to stunted growth. Summary of the Invention

[0008] In view of this, the present invention provides a polyethylene material, its preparation method, and its application. This polyethylene material can still effectively store and convert light energy even in rainy weather or when humidity is greater than or equal to 80%, thus solving the problem of plant growth stagnation due to lack of sunlight during cloudy or rainy days and at night.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] A method for preparing a polyethylene material includes the following steps:

[0011] S1: Add hindered phenolic antioxidants to a mixture of allyl organic compounds, organic peroxides and 3-mercaptopropionates to obtain a suspension;

[0012] S2: Mix paraffin wax, stearic acid and high-density polyethylene to obtain polyethylene masterbatch;

[0013] S3: Under stirring conditions, the suspension, the first organic solvent and the polyethylene masterbatch are mixed and reacted, and then extruded to obtain mixed masterbatch;

[0014] S4: Mix the masterbatch with rhodamine in a second organic solvent to obtain the polyethylene material.

[0015] In an optional embodiment, in step S1, the mass ratio of the allyl organic compound, the organic peroxide, the 3-mercaptopropionate, and the hindered phenolic antioxidant is (0.4-0.8):(1.0-1.2):(0.04-0.07):(0.4-0.3).

[0016] In one optional embodiment, in step S2, the mass ratio of the paraffin, the stearic acid and the high-density polyethylene is (2-2.5):(0.8-1.3):(50-65).

[0017] In an optional embodiment, in step S3, the mass-to-volume ratio of the suspension to the first organic solvent is 1 g:(8-17) mL; the mass ratio of the suspension to the polyethylene masterbatch is 1:(230-290).

[0018] In an optional embodiment, in step S4, the mass ratio of the mixed masterbatch to the rhodamine is (80-100):1. The specific amount of the second organic solvent is not limited, as long as it is sufficient to fully disperse and mix the rhodamine and the mixed masterbatch. For example, the mass-to-volume ratio of rhodamine to the second organic solvent is 1g:(6-13)mL.

[0019] In an optional embodiment, in step S1, the allyl organic compound, the organic peroxide, and the 3-mercaptopropionate are stirred and mixed at 30-40°C and 300-500 r / min for 30-50 min to obtain a mixture.

[0020] In an optional embodiment, in step S1, after the mixture is cooled to 20-30°C, the hindered phenolic antioxidant is added, and the mixture is stirred and mixed at 300-500 r / min for 3-4 h to obtain a suspension.

[0021] In an optional embodiment, in step S2, the mixing conditions of paraffin wax, stearic acid, and high-density polyethylene (powder or granules, preferably powder) are not specifically limited, as long as all components are uniformly mixed without any layering or unevenness, and without causing material decomposition or damage. For example, mixing can be achieved by continuous stirring during heating, with the heating temperature gradually increasing. Preferably, the paraffin wax, stearic acid, and high-density polyethylene are stirred at a low speed of 50-200 r / min at 30-35°C for 10-15 min, and then heated to 110-140°C for homogenization.

[0022] In one optional embodiment, in step S3, the mixing reaction is carried out at a temperature of 50-80°C for 5-8 hours.

[0023] In one alternative implementation, in step S3, the stirring rate is 600-800 r / min.

[0024] In one optional implementation, in step S3, the extrusion temperature is 130-150°C.

[0025] In one alternative embodiment, the 3-mercaptopropionate is selected from 2-ethylhexyl 3-mercaptopropionate or isooctyl 3-mercaptopropionate.

[0026] In one optional embodiment, the organic peroxide is selected from at least one of tert-butyl peroxide, benzoyl peroxide, and dicumyl peroxide. The tert-butyl peroxide is selected from α,α-bis(tert-butylperoxy)dicumyl peroxide, di(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, or 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne.

[0027] In one optional embodiment, the allyl organic compound is selected from at least one of triallyl isocyanurate, trimethylolpropane trimethacrylate, and polytriallyl isocyanurate.

[0028] In one alternative embodiment, the hindered phenolic antioxidant is selected from at least one of 2,6-di-tert-butyl-4-methylphenol, bis(3,5-di-tert-butyl-4-hydroxyphenyl) sulfide, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0029] In one alternative embodiment, the first organic solvent is selected from ethanol, methanol, or acetone, etc.

[0030] In one alternative embodiment, the second organic solvent is selected from dichloromethane, acetone, ethyl acetate, or chloroform, etc.

[0031] The preferred rhodamine mentioned above is Rhodamine 6G, also known as Rose Red 6G, Rhodamine 6G, Rhodamine 6G, and Basic Red. It has two polymorphs: a stable red polymorph B and a yellow polymorph A. Its molecular formula is C. 28 H 31 ClN2O3 has a molecular weight of 479.02.

[0032] The present invention also provides a polyethylene material prepared by the above-described polyethylene material preparation method.

[0033] The present invention also provides the application of the polyethylene material prepared by the above-mentioned polyethylene material preparation method in the preparation of greenhouse film, packaging film or coating material.

[0034] This invention also provides an agricultural light-converting greenhouse film, made from polyethylene material prepared by the above-mentioned polyethylene material preparation method. Compared with existing greenhouse films, the agricultural light-converting greenhouse film provided by this invention can still effectively store and convert light energy in rainy weather or in weather with humidity greater than 80%, while also having a better heat storage function and superior film strength and toughness (due to micro-crosslinking).

[0035] The beneficial effects of this invention are as follows:

[0036] Beneficial Effect 1: The polyethylene material preparation method provided by this invention involves the allyl group in allyl organic compounds undergoing a polymerization reaction with polyethylene under the action of free radicals generated from the decomposition of organic peroxides to form covalent bonds. Simultaneously, the thiol group (-SH) in 3-mercaptopropionate can react with free radicals, terminating chain growth or undergoing cross-linking reactions to form a cross-linked network. This introduces functional side chains or cross-linked structures into polyethylene, enhancing the structural stability and durability of the polyethylene material. Furthermore, it allows for control of cross-linking density, adjusting the mechanical and thermal properties of the polyethylene material. Based on this, the phase change material paraffin absorbs solar energy, and stearic acid enhances light absorption. The synergistic effect between paraffin and stearic acid improves the application potential of paraffin in solar thermal conversion and storage systems. When the phase change material paraffin absorbs solar radiation, this energy is stored in the polyethylene material with a regular grid structure. When the temperature decreases, the polyethylene material releases the stored heat. At the same time, Rhodamine, which has a strong fluorescent effect, is used to make polyethylene materials emit light under ultraviolet light or other specific wavelength light sources. Due to the good hydrophilicity of Rhodamine, its luminescence efficiency is basically not affected even after the material is soaked in water on rainy days.

[0037] In summary, the polyethylene material prepared by the method provided by this invention enhances light absorption and luminescence efficiency, thereby extending the luminescence time and enabling automatic supplemental lighting on cloudy or rainy days. Specifically, it absorbs solar heat during the day and then provides supplemental lighting in the form of light on cloudy or rainy days and in the evening, without requiring additional energy consumption, thus extending the luminescence and illumination time and maintaining stable light color. Even in rainy or humid environments, it retains its long-term energy storage and light conversion function. Especially under long-term use, it exhibits better long-term energy storage performance and light conversion efficiency, solving the problem of insufficient light supplementation for plants in greenhouses on cloudy days and at night, and improving plant growth efficiency and yield.

[0038] Beneficial Effect 2: The polyethylene material preparation method provided by this invention can achieve the corresponding effect by adding a small amount of rhodamine. Moreover, the addition of rhodamine will not affect the transparency of the greenhouse film prepared later. Furthermore, it directly utilizes sustainable solar energy, which is energy-saving and environmentally friendly.

[0039] Beneficial Effect 3: The polyethylene material preparation method provided by this invention modifies the polyethylene material by adding allyl organic compounds, organic peroxides, 3-mercaptopropionate and hindered phenolic antioxidants, combined with paraffin, stearic acid and rhodamine, etc., thereby enhancing the mechanical properties, weather resistance and long-term energy storage performance of the polyethylene material itself, and ensuring the actual effect in the greenhouse application process. Detailed Implementation

[0040] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the content of the present invention.

[0041] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0042] The present invention is further illustrated below by way of examples, but it is not intended to be limited thereto.

[0043] Example 1

[0044] (1) Add 50g triallyl isocyanurate, 100g benzoyl peroxide and 5g isooctyl 3-mercaptopropionate to a stirred tank and stir at 35℃ and 300r / min for 40 minutes to obtain a mixture; then cool the mixture to 22℃ and add 20g of hindered phenolic antioxidant 2,6-di-tert-butyl-4-methylphenol and stir at 300r / min for 3 hours to obtain a suspension.

[0045] (2) Add 2kg of paraffin and 1kg of stearic acid to 50kg of high-density polyethylene powder, stir for 12 minutes at 32℃ and 100r / min in a variable temperature high mixer, and gradually heat the mixture to 120℃ using a heater, maintain the temperature and continue stirring to ensure that all components are mixed evenly to obtain polyethylene masterbatch.

[0046] (3) After diluting the above suspension with 2L of ethanol, transfer it to a rotary drum reactor, add 50kg of polyethylene masterbatch obtained in step (2), and rotate and react for 6 hours at a stirring speed of 700r / min at 60℃. Then, extrude the mixture on a single screw extruder at 140℃ to obtain mixed masterbatch.

[0047] (4) Mix 5kg of the above mixed masterbatch with 50g of Rhodamine 6G in 400ml of dichloromethane, then extrude it from the extruder to form a circular tubular film, and expand it into a bubble by blowing air. Finally, cool it and cut it into a flat film, which is the greenhouse film.

[0048] Example 2

[0049] (1) Add 60g of triallyl isocyanurate, 120g of dicumyl peroxide and 6g of 2-ethylhexyl 3-mercaptopropionate to a stirred tank and stir at 38°C and 400r / min for 45 minutes to obtain a mixture; then cool the mixture to 23°C and add 30g of hindered phenolic antioxidant bis(3,5-di-tert-butyl-4-hydroxyphenyl) sulfide and stir at 400r / min for 3.5 hours to obtain a suspension.

[0050] (2) Add 2.5 kg of paraffin and 1.25 kg of stearic acid to 50 kg of high-density polyethylene granules, stir for 15 minutes at 34 °C and 180 r / min in a variable temperature high mixer, and gradually heat the mixture to 125 °C using a heater, maintain the temperature and continue stirring to ensure that all components are mixed evenly to obtain polyethylene masterbatch.

[0051] (3) After diluting the above suspension with 2.5L of methanol, transfer it to a rotary drum reactor, add 50kg of polyethylene masterbatch obtained in step (2), and rotate and react at 70℃ and 750r / min for 7.5 hours. Then, extrude the mixture on a single screw extruder at 145℃ to obtain mixed masterbatch.

[0052] (4) Mix 4.8 kg of the above mixed masterbatch with 60 g of Rhodamine 6G molecules in 400 ml of dichloromethane, and then make greenhouse film according to the same method as in Example 1 (blow molding).

[0053] Example 3

[0054] (1) Add 40g triallyl isocyanurate, 110g α,α-bis(tert-butylperoxy)diisopropylbenzene and 4g isooctyl 3-mercaptopropionate to a stirred tank and stir at 33°C and 350r / min for 35 minutes to obtain a mixture; then cool the mixture to 26°C and add 25g of hindered phenolic antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and stir at 350r / min for 3.5 hours to obtain a suspension.

[0055] (2) Add 2.25 kg of paraffin and 1.1 kg of stearic acid to 50 kg of high-density polyethylene powder, stir for 10 minutes at 31 °C and 50 r / min in a variable temperature high mixer, and gradually heat the mixture to 115 °C using a heater, maintain the temperature and continue stirring to ensure that all components are mixed evenly to obtain polyethylene masterbatch.

[0056] (3) After diluting the above suspension with 3L of acetone, transfer it to a rotary drum reactor, add 50kg of polyethylene masterbatch obtained in step (2), and rotate and react at 55℃ and 780r / min for 5.5 hours. Then, extrude the mixture on a single screw extruder at 135℃ to obtain mixed masterbatch.

[0057] (4) Mix 3.6 kg of the above mixed masterbatch with 40 g of Rhodamine 6G molecules in 500 ml of acetone, and then make greenhouse film according to the same method as in Example 1 (blow molding).

[0058] Example 4

[0059] (1) Add 70g triallyl isocyanurate, 105g di(tert-butylperoxyisopropyl)benzene and 6g isooctyl 3-mercaptopropionate to a stirred tank and stir at 36°C and 450r / min for 45 minutes to obtain a mixture; then cool the mixture to 28°C and add 22g of hindered phenolic antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and stir at 450r / min for 4 hours to obtain a suspension.

[0060] (2) Add 2.4 kg of paraffin and 1.1 kg of stearic acid to 60 kg of high-density polyethylene powder, stir for 12 minutes at 33°C and 200 r / min in a variable temperature high mixer, and gradually heat the mixture to 130°C using a heater, maintain the temperature and continue stirring to ensure that all components are mixed evenly to obtain polyethylene masterbatch.

[0061] (3) After diluting the above suspension with 2.8L of ethanol, transfer it to a rotary drum reactor, add 60kg of polyethylene masterbatch obtained in step (2), and rotate and react for 8 hours at a stirring speed of 720r / min at 75℃. Then, extrude the mixture on a single screw extruder at 145℃ to obtain mixed masterbatch.

[0062] (4) Mix 6.3 kg of the above mixed masterbatch with 65 g of Rhodamine 6G molecules in 550 ml of chloroform, and then make greenhouse film according to the same method as in Example 1 (blow molding).

[0063] Example 5

[0064] (1) Add 65g of trimethylolpropane trimethacrylate, 115g of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane and 6g of isooctyl 3-mercaptopropionate to a stirred tank and stir at 34°C and 350r / min for 50 minutes to obtain a mixture; then cool the mixture to 23°C and add 20g of hindered phenolic antioxidant bis(3,5-di-tert-butyl-4-hydroxyphenyl) sulfide and stir at 350r / min for 3 hours to obtain a suspension.

[0065] (2) Add 2.2 kg of paraffin and 1.0 kg of stearic acid to 55 kg of high-density polyethylene powder, stir for 14 minutes at 32 °C and 90 r / min in a variable temperature high mixer, and gradually heat the mixture to 125 °C using a heater, maintain the temperature and continue stirring to ensure that all components are mixed evenly to obtain polyethylene masterbatch.

[0066] (3) After diluting the above suspension with 2.5L of ethanol, transfer it to a rotary drum reactor, add 55kg of polyethylene masterbatch obtained in step (2), and rotate and react for 6 hours at a stirring speed of 650r / min at 65℃. Then, extrude the mixture on a single screw extruder at 140℃ to obtain mixed masterbatch.

[0067] (4) Mix 5.4 kg of the above mixed masterbatch with 60 g of Rhodamine 6G molecules in 360 ml of ethyl acetate, and then make greenhouse film according to the same method as in Example 1 (blow molding).

[0068] Example 6

[0069] (1) Add 60g of polytriallyl isocyanurate, 110g of benzoyl peroxide and 7g of isooctyl 3-mercaptopropionate to a stirred tank and stir at 37°C and 500r / min for 40 minutes to obtain a mixture; then cool the mixture to 22°C and add 18g of hindered phenolic antioxidant 2,6-di-tert-butyl-4-methylphenol and stir at 500r / min for 4 hours to obtain a suspension.

[0070] (2) Add 2 kg of paraffin and 0.9 kg of stearic acid to 50 kg of high-density polyethylene powder, stir for 12 minutes at 31 °C and 70 r / min in a variable temperature high mixer, and gradually heat the mixture to 120 °C using a heater, maintain the temperature and continue stirring to ensure that all components are mixed evenly to obtain polyethylene masterbatch.

[0071] (3) After diluting the above suspension with 2.2L of ethanol, transfer it to a rotary drum reactor, add 50kg of polyethylene masterbatch obtained in step (2), and rotate and react for 5 hours at a stirring speed of 600r / min at 55℃. Then, extrude the mixture on a single screw extruder at 135℃ to obtain mixed masterbatch.

[0072] (4) Mix 4.6 kg of the above mixed masterbatch with 55 g of Rhodamine 6G molecules in 500 ml of chloroform, and then make greenhouse film according to the same method as in Example 1 (blow molding).

[0073] Example 7

[0074] (1) Add 75g of triallyl isocyanurate, 120g of α,α-bis(tert-butylperoxy)diisopropylbenzene and 7g of isooctyl 3-mercaptopropionate to a stirred tank, and stir at 39°C and 420r / min for 45 minutes to obtain a mixture; then cool the mixture to 23°C and add 25g of hindered phenolic antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and stir at 420r / min for 3 hours to obtain a suspension.

[0075] (2) Add 2.6 kg of paraffin and 1.2 kg of stearic acid to 65 kg of high-density polyethylene powder, stir for 15 minutes at 34 °C and 150 r / min in a variable temperature high mixer, and gradually heat the mixture to 135 °C using a heater, maintain the temperature and continue stirring to ensure that all components are mixed evenly to obtain polyethylene masterbatch.

[0076] (3) After diluting the above suspension with 3L of ethanol, transfer it to a rotary drum reactor, add 65kg of polyethylene masterbatch obtained in step (2), and rotate and react for 7 hours at a stirring speed of 750r / min at 80℃. Then, extrude the mixture on a single screw extruder at 150℃ to obtain mixed masterbatch.

[0077] (4) Mix 6.3 kg of the above mixed masterbatch with 70 g of Rhodamine 6G molecules in 630 mL of dichloromethane, and then make greenhouse film according to the same method as in Example 1 (blow molding).

[0078] Comparative Example 1

[0079] This comparative example is similar to Example 7, except that step (1) in Example 7 is omitted in this comparative example. The specific preparation method of this comparative example includes the following steps:

[0080] (1) Add 2.6 kg of paraffin and 1.2 kg of stearic acid to 65 kg of high-density polyethylene powder, stir for 15 minutes at 34 °C and 150 r / min in a variable temperature high mixer, and gradually heat the mixture to 135 °C using a heater, maintain the temperature and continue stirring to ensure that all components are mixed evenly to obtain polyethylene masterbatch.

[0081] (2) Add 65 kg of polyethylene masterbatch obtained in step (1) and dilute it with 3 L of ethanol. Then transfer it to a rotary drum reactor and rotate it at 80 °C and 750 r / min for 7 hours. Then extrude it on a single screw extruder at 150 °C to obtain mixed masterbatch.

[0082] (3) Mix 6.3 kg of the above mixed masterbatch with 70 g of Rhodamine 6G molecules in 630 mL of dichloromethane, and then make greenhouse film according to the same method as in Example 1 (blow molding).

[0083] Comparative Example 2

[0084] This comparative example is similar to Example 7, except that low-density polyethylene is used instead of high-density polyethylene in this comparative example. The specific preparation method of this comparative example includes the following steps:

[0085] (1) Add 75g of triallyl isocyanurate, 120g of α,α-bis(tert-butylperoxy)diisopropylbenzene and 7g of isooctyl 3-mercaptopropionate to a stirred tank, and stir at 39°C and 420r / min for 45 minutes to obtain a mixture; then cool the mixture to 23°C and add 25g of hindered phenolic antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and stir at 420r / min for 3 hours to obtain a suspension.

[0086] (2) Add 2.6 kg of paraffin and 1.2 kg of stearic acid to 65 kg of low-density polyethylene powder, stir for 15 minutes at 34 °C and 50 r / min in a variable temperature high mixer, and gradually heat the mixture to 135 °C using a heater, maintain the temperature and continue stirring to ensure that all components are mixed evenly to obtain polyethylene masterbatch.

[0087] (3) After diluting the above suspension with 3L of ethanol, transfer it to a rotary drum reactor, add 65kg of polyethylene masterbatch obtained in step (2), and rotate and react for 7 hours at a stirring speed of 750r / min at 80℃. Then, extrude the mixture on a single screw extruder at 150℃ to obtain mixed masterbatch.

[0088] (4) Mix 6.3 kg of the above mixed masterbatch with 70 g of Rhodamine 6G molecules in 630 mL of dichloromethane, and then make greenhouse film according to the same method as in Example 1 (blow molding).

[0089] Comparative Example 3

[0090] This comparative example is similar to Example 7, except that the step of preparing polyethylene masterbatch is omitted in this comparative example. The preparation method of this comparative example includes the following steps:

[0091] (1) Add 75g of triallyl isocyanurate, 120g of α,α-bis(tert-butylperoxy)diisopropylbenzene and 7g of isooctyl 3-mercaptopropionate to a stirred tank, and stir at 39°C and 420r / min for 45 minutes to obtain a mixture; then cool the mixture to 23°C and add 25g of hindered phenolic antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and stir at 420r / min for 3 hours to obtain a suspension.

[0092] (2) Add 2.6 kg of paraffin, 1.2 kg of stearic acid and 65 kg of high-density polyethylene powder directly to the suspension. Stir for 15 minutes at 34°C and 150 r / min in a variable temperature high mixer. Gradually heat the mixture to 135°C using a heater, maintain the temperature and continue stirring to ensure that all components are mixed evenly.

[0093] (3) The mixture obtained in step (2) is transferred to a rotary drum reactor and rotated at 80°C and 750 r / min for 7 hours. Then it is extruded on a single screw extruder at 150°C to obtain mixed masterbatch.

[0094] (4) Mix 6.3 kg of the above mixed masterbatch with 70 g of Rhodamine 6G molecules in 630 mL of dichloromethane, and then make greenhouse film according to the same method as in Example 1 (blow molding).

[0095] Comparative Example 4

[0096] This comparative example is similar to Example 7, except that BASF's plastic additive Tinuvin NOR is used in this comparative example. TM The preparation method of this comparative example, using 371 instead of Rhodamine 6G, includes the following steps:

[0097] (1) Add 75g of triallyl isocyanurate, 120g of α,α-bis(tert-butylperoxy)diisopropylbenzene and 7g of isooctyl 3-mercaptopropionate to a stirred tank, and stir at 39°C and 420r / min for 45 minutes to obtain a mixture; then cool the mixture to 23°C and add 25g of hindered phenolic antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and stir at 420r / min for 3 hours to obtain a suspension.

[0098] (2) Add 2.6 kg of paraffin and 1.2 kg of stearic acid to 65 kg of high-density polyethylene powder, stir for 15 minutes at 34 °C and 50 r / min in a variable temperature high mixer, and gradually heat the mixture to 135 °C using a heater, maintain the temperature and continue stirring to ensure that all components are mixed evenly to obtain polyethylene masterbatch.

[0099] (3) After diluting the above suspension with 3L of ethanol, transfer it to a rotary drum reactor, add 65kg of polyethylene masterbatch obtained in step (2), and rotate and react for 7 hours at a stirring speed of 750r / min at 80℃. Then, extrude the mixture on a single screw extruder at 150℃ to obtain mixed masterbatch.

[0100] (4) Mix 6.3 kg of the above-mentioned masterbatch with 70 g of BASF plastic additive Tinuvin NOR TM 371. The greenhouse film was made using the same method as in Example 1 (blow molding).

[0101] Experimental Example 1

[0102] The greenhouse films prepared in each embodiment and comparative example were subjected to performance tests, and the test results are shown in the table below. Specifically, the light transmittance and haze were tested according to GB / T 4455-2019, the fluorescence quantum yield was tested according to the relative method, and the tensile strength was tested according to GB / T1040.1-2018.

[0103] The relative method involves constructing a standard curve of the concentration versus fluorescence intensity of a reference fluorescent substance (quinine sulfate), and then comparing the fluorescence intensity of the test sample with that of the reference fluorescent substance to calculate the fluorescence quantum yield of the test sample.

[0104] Emission peak: The emission peak of the sample under test obtained by excitation under 425nm laser.

[0105] Table 1

[0106]

[0107] As shown in the table above, compared with the comparative examples, the polyethylene material provided by this invention exhibits excellent fluorescence quantum yield at higher humidity levels (e.g., 80%-90%). Furthermore, in Comparative Example 1, step (1) of Example 7 was omitted, and high-density polyethylene masterbatch was directly reacted with diluted ethanol. Due to the lack of the initial chemical modification process, the physicochemical properties of the material, especially tensile strength, were poor. In Comparative Example 2, low-density polyethylene was used instead of high-density polyethylene, but the mechanical strength of the final greenhouse film deteriorated. In Comparative Example 3, the step of preparing polyethylene masterbatch was omitted, and paraffin, stearic acid, high-density polyethylene powder, and suspension were directly mixed, directly affecting the material's consistency and properties such as haze and tensile strength. In Comparative Example 4, BASF's plastic additive Tinuvin NOR was used instead of Rhodamine 6G, but the fluorescence quantum yield was significantly reduced under different humidity levels.

[0108] Experiment Example 2

[0109] Twenty-two greenhouses of the same specifications were installed using the greenhouse films prepared in the various embodiments and comparative examples. Eleven greenhouses simulated two environments: Group 1: daytime (sunny) and nighttime (dry); Group 2: daytime (cloudy, with 80% humidity) and nighttime (80% humidity). The same number and density of spinach were then planted in each greenhouse at 20-25℃. The growth height and leaf length of the spinach were monitored after 20 days. The specific results are shown in the table below.

[0110] Light intensity:

[0111] Sunny daytime: 500 μmol·m 2 / s;

[0112] Cloudy during the day: 200 μmol·m 2 / s;

[0113] Night: 0 μmol·m 2 / s;

[0114] Photoperiod: 12 hours of light, 12 hours of darkness.

[0115] Table 2

[0116]

[0117]

[0118] Note: Growth height and leaf length refer to the increase in height and leaf length of spinach throughout the entire experiment.

[0119] The data in the table above shows that spinach grown in greenhouses using polyethylene material provided by this invention grows faster, especially under insufficient light conditions, demonstrating that it has a significant promoting effect on spinach growth on cloudy and rainy days and at night.

[0120] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a polyethylene material, characterized in that, Includes the following steps: S1: Add hindered phenolic antioxidants to a mixture of allyl organic compounds, organic peroxides and 3-mercaptopropionates to obtain a suspension; S2: Mix paraffin wax, stearic acid and high-density polyethylene to obtain polyethylene masterbatch; S3: Under stirring conditions, the suspension, the first organic solvent and the polyethylene masterbatch are mixed and reacted, and then extruded to obtain mixed masterbatch; S4: Mix the masterbatch with rhodamine in a second organic solvent to obtain the polyethylene material.

2. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of the allyl organic compound, the organic peroxide, the 3-mercaptopropionate, and the hindered phenolic antioxidant is (0.4-0.8):(1.0-1.2):(0.04-0.07):(0.1-0.3).

3. The preparation method according to claim 1 or 2, characterized in that, In step S2, the mass ratio of the paraffin, the stearic acid and the high-density polyethylene is (2-2.6):(0.8-1.3):(50-65).

4. The preparation method according to claim 1 or 2, characterized in that, In step S3, the mass-to-volume ratio of the suspension to the first organic solvent is 1 g:(8-17) mL; the mass ratio of the suspension to the polyethylene masterbatch is 1:(230-290).

5. The preparation method according to claim 1 or 2, characterized in that, In step S4, the mass ratio of the mixed masterbatch to the rhodamine is (80-100):

1.

6. The preparation method according to claim 1 or 2, characterized in that, In step S1, the allyl organic compound, the organic peroxide, and the 3-mercaptopropionate are stirred and mixed at 30-40°C and 300-500 r / min for 30-50 min to obtain a mixture.

7. The preparation method according to claim 6, characterized in that, In step S1, after the mixture is cooled to 20-30°C, the hindered phenolic antioxidant is added, and the mixture is stirred and mixed at 300-500 r / min for 3-4 h to obtain a suspension.

8. The preparation method according to claim 1, characterized in that, In step S2, the paraffin, stearic acid, and high-density polyethylene are stirred at 30-35°C and 50-200 r / min for 10-15 min, and then heated to mix thoroughly.

9. The preparation method according to claim 1, characterized in that, In step S3, the mixing reaction temperature is 50-80℃ and the time is 5-8h; the stirring rate is 600-800r / min; and the extrusion temperature is 130-150℃.

10. The preparation method according to claim 1, characterized in that, The 3-mercaptopropionate is selected from 2-ethylhexyl 3-mercaptopropionate or isooctyl 3-mercaptopropionate; The organic peroxide is selected from at least one of tert-butyl peroxide, benzoyl peroxide, and dicumyl peroxide; the tert-butyl peroxide is selected from α,α-bis(tert-butylperoxy)dicumyl, di(tert-butylperoxyisopropyl)benzene, or 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane. The allyl organic compound is selected from at least one of triallyl isocyanurate, triallyl isocyanurate, trimethylolpropane trimethacrylate, and polytriallyl isocyanurate; The hindered phenolic antioxidant is selected from at least one of 2,6-di-tert-butyl-4-methylphenol, bis(3,5-di-tert-butyl-4-hydroxyphenyl) sulfide, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. The first organic solvent is selected from ethanol, methanol, or acetone; The second organic solvent is selected from dichloromethane, acetone, ethyl acetate, or chloroform.

11. A polyethylene material prepared by the method of any one of claims 1-10.

12. The use of a polyethylene material prepared by the method of any one of claims 1-10 in the preparation of greenhouse films, packaging films or coating materials.

13. An agricultural greenhouse film for converting light into color, characterized in that, The polyethylene material is prepared by the polyethylene material preparation method according to any one of claims 1-10.

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