A rare earth doped quantum dot composite light-converting agricultural film and preparation method thereof

Abstract

The present invention relates to the technical field of quantum dot light-converting agricultural film, and in particular to a rare earth-doped quantum dot composite light-converting agricultural film and a preparation method thereof. The light-converting agricultural film comprises a light-converting masterbatch with a mass fraction of 0.2-5% and a polymer matrix with a mass fraction of 95-99.8%; the light-converting masterbatch comprises a red quantum dot light-converting agent with a mass fraction of 10-50%, a green rare earth light-converting agent with a mass fraction of 1-5%, an auxiliary agent with a mass fraction of 1-10%, and a masterbatch matrix, and the red quantum dot light-converting agent is at least one of perovskite quantum dots, II-VI group quantum dots, III-V group quantum dots, IV-VI group quantum dots, carbon quantum dots, and silicon quantum dots; and the green rare earth light-converting agent comprises at least one of Tb, Dy, Ce, Ho, and Pr elements. The advantage is that by adding green rare earth materials, the green rare earth materials absorb energy under the irradiation of sunlight and transfer the energy to the red light quantum dots, thereby enhancing the luminous intensity of the quantum dots.

Description

Technical Field

[0001] The invention relates to the technical field of quantum dot light-converting agricultural films, and in particular to a rare earth-doped quantum dot composite light-converting agricultural film and a preparation method thereof. Background Art

[0002] As a sustainable agricultural production method that continues to grow and develop with the process of agricultural modernization, facility agriculture has become an important symbol of modern agriculture. Agricultural greenhouse films are widely used in vegetable greenhouses, spring arch greenhouses and solar greenhouses in China. As an important measure to promote agricultural production and realize agricultural modernization, it has been recognized and has become an important part of implementing plastic cultivation and other related fields in my country's agricultural production, and has achieved significant economic benefits. As an emerging controlled functional agricultural film, light-converting agricultural film not only has high light transmittance and good temperature regulation effect, but also can efficiently convert ultraviolet rays into blue-violet light or red-orange light that promotes plant growth, improving light energy utilization and plant photosynthesis efficiency. This can significantly increase production, advance harvest time, and improve product quality.

[0003] Based on this, it is extremely important to select suitable light-converting materials to prepare agricultural films. Quantum dots exhibit optical properties of narrow linewidth and high luminescence efficiency, making them ideal single-photon sources. The most obvious advantage of quantum dots is that they have a size effect, that is, by changing the size of quantum dots, a continuously adjustable emission spectrum can be obtained. By selecting specific components and sizes, these particles can emit light in a very wide continuously adjustable spectral range, but the light conversion efficiency of existing quantum dot light-converting agricultural films and the luminescence intensity of quantum dots are relatively low, which limits their application in the agricultural field. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a rare earth doped quantum dot composite light conversion agricultural film and a preparation method thereof. By adding green light rare earth material to the red light quantum dot light conversion agricultural film, the light conversion efficiency of the red light quantum dots in the agricultural film is improved, thereby promoting the photosynthetic growth of crops.

[0005] The first object of the present invention is to provide a rare earth doped quantum dot composite light-converting agricultural film, comprising a light-converting masterbatch and a polymer matrix, wherein the mass fraction of the light-converting masterbatch is 0.2-5%, and the mass fraction of the polymer matrix is ​​95-99.8%;

[0006] The light conversion masterbatch comprises the following components by mass fraction: 10-50% red quantum dot light conversion agent; 1-5% green rare earth light conversion agent; 1-10% auxiliary agent; the remainder is the masterbatch matrix;

[0007] The red quantum dot light conversion agent is at least one of perovskite quantum dots, II-VI group quantum dots, III-V group quantum dots, IV-VI group quantum dots, carbon quantum dots, and silicon quantum dots;

[0008] The green rare earth light conversion agent contains at least one of five rare earth metal elements: Tb, Dy, Ce, Ho, and Pr.

[0009] Preferably, the thickness of the rare earth doped quantum dot composite light-converting agricultural film is 0.5-2 mm.

[0010] Preferably, the masterbatch matrix is ​​at least one of polyvinyl chloride, polyethylene, polypropylene, and ethylene-vinyl acetate copolymer; the auxiliary agent is at least one of polyethylene glycol, polyethylene wax, pentaerythritol stearate, zinc stearate, vinyl bisstearamide, aluminate coupling agent, and titanate coupling agent; the polymer matrix is ​​at least one of polyvinyl chloride, polyethylene, polypropylene, and ethylene-vinyl acetate copolymer.

[0011] Preferably, the mass of the red quantum dot light conversion agent is 0.1-0.5% of the mass of the light conversion agricultural film, and the mass of the green rare earth light conversion agent is 0.01-0.05% of the mass of the light conversion agricultural film.

[0012] The second object of the present invention is to provide a method for preparing a rare earth doped quantum dot composite light conversion agricultural film, comprising the following steps:

[0013] The red quantum dot light conversion agent, the green rare earth light conversion agent, the auxiliary agent and the masterbatch matrix are fed into a twin-screw extruder plasticizing granulator for granulation to obtain a light conversion masterbatch;

[0014] The light-converting masterbatch and the polymer matrix are mixed and put into the barrel of a film blowing machine for blow molding to obtain a rare earth-doped quantum dot composite light-converting agricultural film.

[0015] Preferably, the red quantum dot light conversion agent is prepared by the following method:

[0016] The cadmium source, oleic acid and n-octadecene are mixed to prepare a cadmium-oleic acid solution;

[0017] mixing a zinc source, oleic acid and n-octadecene to prepare a zinc-oleic acid solution;

[0018] dissolving selenium in trioctylphosphine to prepare a trioctylphosphine-selenium solution;

[0019] After degassing n-octadecene and the cadmium-oleic acid solution under vacuum, they are heated to 300-320° C. under nitrogen; then the trioctylphosphine-selenium solution, trioctylphosphine and the zinc-oleic acid solution are added in sequence, and a mixed solution containing the cadmium-oleic acid solution, the trioctylphosphine-selenium solution and n-octadecene is continuously added; after cooling to room temperature, an ethanol solution is added, and a red quantum dot light conversion agent is obtained after centrifugation, drying and grinding.

[0020] Preferably, the cadmium source is cadmium acetate dihydrate; and the zinc source is zinc acetate dihydrate.

[0021] Preferably, the green rare earth light conversion agent is prepared by the following method:

[0022] Weigh lithium nitrate, magnesium nitrate, zirconium nitrate and terbium oxide, dissolve them in deionized water, stir and mix, keep them at 75-85°C for 10-15 hours, and then cool them to room temperature; grind the cooled product into powder to prepare a green rare earth light conversion agent.

[0023] Preferably, the operating temperature of the twin-screw extruder plasticizing granulator is 130-180°C, and the rotation speed is 100-400r / min; the melting temperature of the film blowing machine is 180°C, and the die head temperature is 160°C.

[0024] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0025] The red quantum dot light conversion agent used in the present invention has precise spectrum continuous adjustability. The photoelectric characteristics mainly come from its quantum confinement effect, that is, by controlling the particle size, the absorption and emission wavelengths are adjustable and the fluorescence emission is highly efficient, thereby meeting the wavelength required for plant photosynthesis. Quantum dots have a wide absorption spectrum. The absorption spectrum of organic molecules usually contains one or several absorption bands, while the absorption spectrum cross-section of quantum dots is much larger than that of organic dyes and gradually increases at higher energy, which is conducive to the absorption of ultraviolet rays. Quantum dots are inorganic materials and are not prone to oxidation reactions and water vapor corrosion, so they have ultra-high light and thermal stability.

[0026] The rare earth doped quantum dot composite light conversion agricultural film and the preparation method thereof provided by the present invention add green light rare earth materials to the red light quantum dot light conversion agricultural film, so that the green rare earth material absorbs energy under the irradiation of sunlight and transfers the energy to the red light quantum dots, thereby enhancing the luminescence intensity of the quantum dots. In this process, a high-energy green light may generate two or more red light photons, so the luminescence quantum efficiency is high, which can significantly improve the light conversion efficiency of the red light quantum dots in the agricultural film, promote the photosynthesis of crops and improve their growth and development. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Graphs showing absorption and emission spectra of a red quantum dot light conversion agent provided according to an embodiment of the present invention.

[0028] Figure 2 It is the excitation and emission spectrum diagram of the green rare earth light conversion agent provided according to the embodiment of the present invention.

[0029] Figure 3 It is the emission spectrum diagram of the red quantum dot light conversion agent in Examples 1 to 3 of the present invention.

[0030] Figure 4 It is a solar spectrum provided according to an embodiment of the present invention and a spectrum diagram of the light-transfer agricultural film in Example 2. DETAILED DESCRIPTION

[0031] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are represented by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0033] An embodiment of the present invention provides a rare earth doped quantum dot composite light conversion agricultural film, comprising a light conversion masterbatch and a polymer matrix, wherein the mass fraction of the light conversion masterbatch is 0.2-5%, and the mass fraction of the polymer matrix is ​​95-99.8%.

[0034] The light conversion masterbatch contains the following components by mass fraction:

[0035] Red quantum dot light conversion agent: 10~50%; green rare earth light conversion agent: 1~5%; auxiliary agent: 1~10%; masterbatch matrix: balance.

[0036] The red quantum dot light conversion agent is at least one of perovskite quantum dots, II-VI group quantum dots, III-V group quantum dots, IV-VI group quantum dots, carbon quantum dots, and silicon quantum dots; the green rare earth light conversion agent contains at least one of the five rare earth metal elements Tb, Dy, Ce, Ho, and Pr.

[0037] The masterbatch matrix is ​​at least one of polyvinyl chloride, polyethylene, polypropylene, and ethylene-vinyl acetate copolymer; the auxiliary agent is at least one of polyethylene glycol, polyethylene wax, pentaerythritol stearate, zinc stearate, vinyl bisstearamide, aluminate coupling agent, and titanate coupling agent.

[0038] The polymer matrix is ​​at least one of polyvinyl chloride, polyethylene, polypropylene, and ethylene-vinyl acetate copolymer.

[0039] In a preferred embodiment, the mass of the red quantum dot light conversion agent is 0.1-0.5% of the mass of the light conversion agricultural film, and the mass of the green rare earth light conversion agent is 0.01-0.05% of the mass of the light conversion agricultural film. The structural formula of the red quantum dot light conversion agent is CdSe / Cd x Zn 1−x Se, 0<x≤1; the structural formula of the green rare earth light conversion agent is Li2Mg 1-y ZrO4:yTb 3+ , 0<y≤1.

[0040] The embodiment of the present invention also provides a method for preparing a rare earth doped quantum dot composite light conversion agricultural film, comprising the following steps:

[0041] The red quantum dot light conversion agent, the green rare earth light conversion agent, the auxiliary agent and the masterbatch matrix are fed into a twin-screw extruder plasticizing granulator for granulation to obtain a light conversion masterbatch;

[0042] The light-converting masterbatch and the polymer matrix are mixed and put into the barrel of the film blowing machine for blow molding to obtain the rare earth doped quantum dot composite light-converting agricultural film. The thickness of the rare earth doped quantum dot composite light-converting agricultural film is 0.5-2 mm.

[0043] The above preparation method is described below in conjunction with specific examples.

[0044] Example 1

[0045] Step 1: Preparation of CdSe / Cd x Zn 1−x Se red quantum dot light conversion agent

[0046] (1) Preparation of precursor solution:

[0047] 10 mmol of cadmium acetate dihydrate (Cd(CH3COO)2·2H2O), 10 mL of oleic acid (OA) and 10 mL of n-octadecene (ODE) were uniformly mixed to prepare a 0.5 M Cd-oleic acid solution in a three-necked flask. After degassing at 120°C under vacuum for 1 h, the solution was stored at 100°C under nitrogen.

[0048] 20 mmol of zinc acetate dihydrate (Zn(CH3COO)2·2H2O), 20 mL of OA and 20 mL of ODE were mixed in a three-necked flask to prepare a 0.5 M Zn-oleic acid solution. After degassing under vacuum at 130°C for 1 h, the solution was stored at 120°C under nitrogen.

[0049] 40 mmol of selenium was dissolved in 20 ml of TOP (trioctylphosphine) to prepare a 2 M TOP-Se solution in a glove box.

[0050] Solution A was prepared by mixing 0.5 mL of Cd-oleic acid (0.5 M), 0.125 mL of TOP-Se (2 M), and 0.375 mL of ODE.

[0051] Solution B was prepared by mixing 1.25 mL of Cd-oleic acid (0.5 M), 1.25 mL of TOP-Se (2 M), and 2.5 mL of ODE.

[0052] (2) CdSe / Cd x Zn 1−x Synthesis of Se quantum dots:

[0053] 6mL ODE and 0.2mL Cd-oleic acid (0.5M) were placed in a 100mL three-necked flask and degassed in a vacuum at 120°C for 25min. The reaction flask was then heated to 310°C under nitrogen and 0.1mL TOP-Se (2M) was quickly injected. After 40s of injection of TOP-Se, 1mL TOP was added dropwise for 20s. After 2min, 1mL solution A was continuously added to the reaction flask at a rate of 5mL / h for 12min. 2mL Zn-oleic acid (0.5M) solution at a temperature of 310°C was quickly injected into the reaction flask. Then, solution B was continuously added at a rate of 4 mL / h for 75min. At the same time, Zn-oleic acid (0.5M) solution was injected 3 times at 18.75min, 52.5min and 67.5min, with the volume of each injection being 2mL, 4mL and 2mL respectively. After cooling to room temperature, an equal volume of ethanol solution was added and centrifuged at 7000 r / min for 5 min. CdSe / Cd was obtained after drying and grinding. x Zn 1−x Se red quantum dot light conversion agent.

[0054] Step 2: Preparation of quantum dot composite light-converting agricultural film

[0055] Take 3kg CdSe / Cd x Zn 1−x Se red quantum dot light conversion agent, 0.1kg vinyl bisstearamide and 3kg polyethylene were added to a high-speed mixer in sequence, and the equipment was used to fully stir at high speed. Subsequently, the mixture was extruded through a twin-screw extruder at an operating temperature of 130-180°C and a speed of 100-400r / min. After extrusion, the mixture was granulated by air cooling to finally prepare a light conversion masterbatch.

[0056] Take 1 kg of the light-converting masterbatch prepared above and 99 kg of polyethylene, mix them evenly and blow them into a film using a film blowing machine to obtain the desired light-converting agricultural film, wherein the melting temperature of the film blowing machine is 180° C. and the die head temperature is 160° C.

[0057] Example 2

[0058] Step 1: Preparation of CdSe / Cd x Zn 1−x Se red quantum dot light conversion agent

[0059] (1) Preparation of precursor solution:

[0060] 10 mmol of cadmium acetate dihydrate (Cd(CH3COO)2·2H2O), 10 mL of oleic acid (OA) and 10 mL of n-octadecene (ODE) were uniformly mixed to prepare a 0.5 M Cd-oleic acid solution in a three-necked flask. After degassing at 120°C under vacuum for 1 h, the solution was stored at 100°C under nitrogen.

[0061] 20 mmol of zinc acetate dihydrate (Zn(CH3COO)2·2H2O), 20 mL of OA and 20 mL of ODE were mixed in a three-necked flask to prepare a 0.5 M Zn-oleic acid solution. After degassing under vacuum at 130°C for 1 h, the solution was stored at 120°C under nitrogen.

[0062] 40 mmol of selenium was dissolved in 20 ml of TOP (trioctylphosphine) to prepare a 2 M TOP-Se solution in a glove box.

[0063] Solution A was prepared by mixing 0.5 mL Cd-oleic acid (0.5 M), 0.125 mL TOP-Se (2 M), and 0.375 mL ODE.

[0064] Solution B was prepared by mixing 1.25 mL of Cd-oleic acid (0.5 M), 1.25 mL of TOP-Se (2 M), and 2.5 mL of ODE.

[0065] (2) CdSe / Cd x Zn 1−x Synthesis of Se quantum dots:

[0066] 6mL ODE and 0.2mL Cd-oleic acid (0.5M) were placed in a 100mL three-necked flask and degassed in a vacuum at 120℃ for 25min. The reaction flask was then heated to 310℃ under nitrogen and 0.1mL TOP-Se (2M) was quickly injected. After 40s of injection of TOP-Se, 1mL TOP was added dropwise for 20s. After 2min, 1mL solution A was continuously added to the reaction flask at a rate of 5mL / h for 12min. 2mL Zn-oleic acid (0.5M) solution at a temperature of 310℃ was quickly injected into the reaction flask. Then, solution B was continuously added at a rate of 4mL / h for 75min. At the same time, Zn-oleic acid (0.5M) solution was injected 3 times at 18.75min, 52.5min and 67.5min, with the volume of each injection being 2mL, 4mL and 2mL respectively. After cooling to room temperature, an equal volume of ethanol solution was added and centrifuged at 7000 r / min for 5 min. CdSe / Cd was obtained after drying and grinding. x Zn 1−x Se red quantum dot light conversion agent.

[0067] Step 2: Preparation of Li2Mg 0.92 ZrO4:0.08Tb 3+ Green rare earth light conversion agent

[0068] According to the preferred ratio, 2 mol of lithium nitrate (LiNO3), 0.92 mol of magnesium nitrate (Mg(NO3)2), 1 mol of zirconium nitrate (Zr(NO3)4) and 0.08 mol of terbium (III) oxide (Tb4O7) were weighed and dissolved in double distilled deionized water, and uniform mixing was achieved with the help of a magnetic stirrer. After the dissolution was completed, the solutions were combined in a beaker to ensure that the concentration of each solution was consistent, and the magnetic stirrer was used to mix them again. Then, the mixed solution was placed in an oven at 80°C for 12 hours. After the insulation was completed, the oven was turned off and the product was allowed to cool naturally to room temperature. Finally, the cooled product was ground into powder to obtain the desired green rare earth light conversion agent.

[0069] Step 3: Preparation of rare earth doped quantum dot composite light-converting agricultural film with high light-converting efficiency

[0070] Take 3kg CdSe / Cd x Zn 1−x Se red quantum dot light conversion agent, 0.3kg Li2Mg 0.92 ZrO4:0.08Tb 3+Green rare earth light conversion agent, 0.1kg vinyl bis stearamide and 3kg polyethylene were added to a high-speed mixer in sequence, and the mixture was fully stirred at high speed using the device. Subsequently, the mixture was extruded through a twin-screw extruder at an operating temperature of 130-180°C and a speed of 100-400r / min. After extrusion, the mixture was granulated by air cooling to finally prepare light conversion masterbatch.

[0071] Take 1 kg of the light-converting masterbatch prepared above and 99 kg of polyethylene, mix them evenly and blow them into a film using a film blowing machine to obtain the desired light-converting agricultural film, wherein the melting temperature of the film blowing machine is 180° C. and the die head temperature is 160° C.

[0072] Example 3

[0073] Step 1: Preparation of CdSe / Cd x Zn 1−x Se red quantum dot light conversion agent

[0074] (1) Preparation of precursor solution:

[0075] 10 mmol of cadmium acetate dihydrate (Cd(CH3COO)2·2H2O), 10 mL of oleic acid (OA) and 10 mL of n-octadecene (ODE) were uniformly mixed to prepare a 0.5 M Cd-oleic acid solution in a three-necked flask. After degassing at 120°C under vacuum for 1 h, the solution was stored at 100°C under nitrogen.

[0076] 20 mmol of zinc acetate dihydrate (Zn(CH3COO)2·2H2O), 20 mL of OA and 20 mL of ODE were mixed in a three-necked flask to prepare a 0.5 M Zn-oleic acid solution. After degassing under vacuum at 130°C for 1 h, the solution was stored at 120°C under nitrogen.

[0077] 40 mmol of selenium was dissolved in 20 ml of TOP (trioctylphosphine) to prepare a 2 M TOP-Se solution in a glove box.

[0078] Solution A was prepared by mixing 0.5 mL of Cd-oleic acid (0.5 M), 0.125 mL of TOP-Se (2 M), and 0.375 mL of ODE.

[0079] Solution B was prepared by mixing 1.25 mL of Cd-oleic acid (0.5 M), 1.25 mL of TOP-Se (2 M), and 2.5 mL of ODE.

[0080] (2) CdSe / Cd x Zn 1−x Synthesis of Se quantum dots:

[0081] 6mL ODE and 0.2mL Cd-oleic acid (0.5M) were placed in a 100mL three-necked flask and degassed in a vacuum at 120℃ for 25min. The reaction flask was then heated to 310℃ under nitrogen and 0.1mL TOP-Se (2M) was quickly injected. After 40s of injection of TOP-Se, 1mL TOP was added dropwise for 20s. After 2min, 1mL solution A was continuously added to the reaction flask at a rate of 5mL / h for 12min. 2mL Zn-oleic acid (0.5M) solution at a temperature of 310℃ was quickly injected into the reaction flask. Then, solution B was continuously added at a rate of 4mL / h for 75min. At the same time, Zn-oleic acid (0.5M) solution was injected 3 times at 18.75min, 52.5min and 67.5min, with the volume of each injection being 2mL, 4mL and 2mL respectively. After cooling to room temperature, an equal volume of ethanol solution was added and centrifuged at 7000 r / min for 5 min. CdSe / Cd was obtained after drying and grinding. x Zn 1−x Se red quantum dot light conversion agent.

[0082] Step 2: Preparation of Li2Mg 0.92 ZrO4:0.08Tb 3+ Green rare earth light conversion agent

[0083] According to the preferred ratio, 2 mol of lithium nitrate (LiNO3), 0.92 mol of magnesium nitrate (Mg(NO3)2), 1 mol of zirconium nitrate (Zr(NO3)4) and 0.08 mol of terbium (III) oxide (Tb4O7) were weighed and dissolved in double distilled deionized water, and uniform mixing was achieved with the help of a magnetic stirrer. After the dissolution was completed, the solutions were combined in a beaker to ensure that the concentration of each solution was consistent, and the magnetic stirrer was used to mix them again. Then, the mixed solution was placed in an oven at 80°C for 12 hours. After the insulation was completed, the oven was turned off and the product was allowed to cool naturally to room temperature. Finally, the cooled product was ground into powder to obtain the desired green rare earth light conversion agent.

[0084] Step 3: Preparation of rare earth doped quantum dot composite light-converting agricultural film with high light-converting efficiency

[0085] Take 3kg CdSe / Cd x Zn 1−x Se red quantum dot light conversion agent, 0.6kg Li2Mg 0.92 ZrO4:0.08Tb 3+Green rare earth light conversion agent, 0.1kg vinyl bis stearamide and 3kg polyethylene were added to a high-speed mixer in sequence, and the mixture was fully stirred at high speed using the device. Subsequently, the mixture was extruded through a twin-screw extruder at an operating temperature of 130-180°C and a speed of 100-400r / min. After extrusion, the mixture was granulated by air cooling to finally prepare light conversion masterbatch.

[0086] Take 1 kg of the light-converting masterbatch prepared above and 99 kg of polyethylene, mix them evenly and blow them into a film using a film blowing machine to obtain the desired light-converting agricultural film, wherein the melting temperature of the film blowing machine is 180° C. and the die head temperature is 160° C.

[0087] Figure 1 The absorption and emission spectra of the red quantum dot light conversion agent are shown in Figure 1, and the emission peak is located at 635nm; Figure 2 This is the excitation and emission spectra of the green rare earth light conversion agent. Its main excitation peaks are located at 284nm, 354nm, 371nm and 380nm, and the emission peaks are located at 543nm and 552nm.

[0088] Figure 3 The emission spectra of the red quantum dot light conversion agents in Examples 1 to 3 are shown. Figure 3 As shown, after the green rare earth light conversion agent is added in Example 2, the green light energy is converted into red light energy due to the energy down-conversion process, thereby enhancing the luminescence intensity of the red light quantum dots; while after an excess of green rare earth light conversion agent is added in Example 3, the luminescence intensity of the red quantum dots is reduced, which is attributed to the possible fluorescence quenching effect between the excess rare earth material and the quantum dots, resulting in a decrease in the luminescence efficiency of the red quantum dots.

[0089] Figure 4 The solar spectrum and the spectrum of the light-transfer agricultural film in Example 2 are as follows: Figure 4 As shown in the figure, after sunlight passes through the light-converting agricultural film, the intensity of the ultraviolet wavelength is significantly reduced, while the intensity of the corresponding red light band is significantly enhanced. This phenomenon is attributed to the role of the light-converting agent, which absorbs the energy of ultraviolet light and converts it into red light, thereby promoting plant photosynthesis.

[0090] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0091] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A rare earth doped quantum dot composite light conversion agricultural film, characterized in that: It comprises a light conversion masterbatch and a polymer matrix, wherein the mass fraction of the light conversion masterbatch is 0.2-5%, and the mass fraction of the polymer matrix is ​​95-99.8%; The light conversion masterbatch comprises the following components by mass fraction: 10-50% red quantum dot light conversion agent; 1-5% green rare earth light conversion agent; 1-10% auxiliary agent; the remainder is the masterbatch matrix; The red quantum dot light conversion agent is prepared by the following method: The cadmium source, oleic acid and n-octadecene are mixed to prepare a cadmium-oleic acid solution; Mixing a zinc source, oleic acid and n-octadecene to prepare a zinc-oleic acid solution; dissolving selenium in trioctylphosphine to prepare a trioctylphosphine-selenium solution; After degassing n-octadecene and the cadmium-oleic acid solution under vacuum, heat to 300-320° C. under nitrogen; then add the trioctylphosphine-selenium solution, trioctylphosphine and the zinc-oleic acid solution in sequence, and continue to add a mixed solution containing the cadmium-oleic acid solution, the trioctylphosphine-selenium solution and n-octadecene; after cooling to room temperature, add an ethanol solution, centrifuge, dry and grind to obtain a red quantum dot light conversion agent; The green rare earth light conversion agent is prepared by the following method: Weigh lithium nitrate, magnesium nitrate, zirconium nitrate and terbium oxide, dissolve them in deionized water, stir and mix, keep them at 75-85°C for 10-15 hours, and then cool them to room temperature; grind the cooled product into powder to prepare a green rare earth light conversion agent.

2. The rare earth doped quantum dot composite light conversion agricultural film according to claim 1, characterized in that: The thickness of the rare earth doped quantum dot composite light-converting agricultural film is 0.5-2 mm.

3. The rare earth doped quantum dot composite light conversion agricultural film according to claim 2, characterized in that: The masterbatch matrix is ​​at least one of polyvinyl chloride, polyethylene, polypropylene, and ethylene-vinyl acetate copolymer; the auxiliary agent is at least one of polyethylene glycol, polyethylene wax, pentaerythritol stearate, zinc stearate, vinyl bisstearamide, aluminate coupling agent, and titanate coupling agent; the polymer matrix is ​​at least one of polyvinyl chloride, polyethylene, polypropylene, and ethylene-vinyl acetate copolymer.

4. The rare earth doped quantum dot composite light conversion agricultural film according to claim 3, characterized in that: The mass of the red quantum dot light conversion agent is 0.1-0.5% of the mass of the light conversion agricultural film, and the mass of the green rare earth light conversion agent is 0.01-0.05% of the mass of the light conversion agricultural film.

5. The method for preparing the rare earth doped quantum dot composite light conversion agricultural film according to any one of claims 1 to 4, characterized in that: The steps include: The red quantum dot light conversion agent, the green rare earth light conversion agent, the auxiliary agent and the masterbatch matrix are fed into a twin-screw extruder plasticizing granulator for granulation to obtain a light conversion masterbatch; The light-converting masterbatch and the polymer matrix are mixed and put into the barrel of a film blowing machine for blow molding to obtain a rare earth-doped quantum dot composite light-converting agricultural film.

6. The method for preparing the rare earth doped quantum dot composite light conversion agricultural film according to claim 5, characterized in that: The cadmium source is cadmium acetate dihydrate; the zinc source is zinc acetate dihydrate.

7. The method for preparing the rare earth doped quantum dot composite light conversion agricultural film according to claim 6, characterized in that: The operating temperature of the twin-screw extruder plasticizing granulator is 130-180°C, and the rotation speed is 100-400r / min; the melting temperature of the film blowing machine is 180°C, and the die head temperature is 160°C.

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