Infrared screening agent of tin oxide system and agricultural cooling film prepared by using infrared screening agent

Abstract

The invention belongs to the technical field of agricultural films, and discloses an infrared screening agent of a tin oxide system and an agricultural cooling film prepared from the infrared screening agent. The general chemical formula of the infrared screening agent of the tin oxide system is (Sn1-xMx) O2: F, wherein 0 lt; x is less than or equal to 0.9, 0lt; f / O < = 0.3; m comprises one or a combination of any more of Ga, In, Sb, Bi, Mo, W, La and Yb. The infrared screening agent can effectively absorb infrared rays and has high selective permeability to visible light. The agricultural cooling film prepared from the composite material is low in cost, can effectively absorb near infrared rays in sunlight to achieve an obvious cooling effect, is high in visible light transmittance, and does not affect normal photosynthesis of plants.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural films, and in particular relates to a tin oxide system infrared shielding agent and an agricultural cooling film prepared by using the same. Background Art

[0002] Heat damage refers to an agricultural meteorological disaster in which high temperatures cause damage to plant growth, development and yield. It is generally caused by high temperatures exceeding the upper limit of plant growth and development.

[0003] The impact of heat damage on crops mainly includes two aspects, one is the physiological mechanism, and the other is the appearance and growth and development. In terms of physiological mechanism, high temperature will destroy the photosynthesis of crops. For example, when the temperature is too high, the chloroplast structure in the leaves of crops may be destroyed. Chloroplasts are the place where crops carry out photosynthesis, and the structures such as thylakoid membranes are sensitive to temperature. Under high temperature, the lipid composition of the thylakoid membrane may undergo phase change, resulting in changes in the fluidity of the membrane, affecting the absorption, transmission and conversion of light energy in photosynthesis. In addition, high temperature will increase and unbalance respiration. Under normal circumstances, the respiration of crops provides energy for life activities, but under high temperature, respiration will be excessively enhanced. This will consume too much photosynthetic products and reduce the accumulation of dry matter in plants. For example, when some cool-loving crops encounter high temperature weather, the respiration rate may increase several times compared to normal temperature, causing a large amount of organic matter originally used for growth and storage to be consumed. In terms of appearance and growth and development, high temperature will cause crop leaves to burn. For example, in summer when the temperature is high and the light is strong, the edges or entire leaves of many crops will be scorched. This is because high temperatures cause excessive evaporation of water in leaf cells, and some physiological processes in the cells become disordered, leading to cell death. High temperatures can affect the flowering and fruiting of crops. For some fruit trees, such as apples, high temperatures during flowering can affect pollen vitality and stigma receptivity, leading to poor pollination and, in turn, affecting fruit yield and quality.

[0004] Agricultural cooling film is a film that can cool crops. Usually, infrared shielding agents are added to the film to play a cooling role. Infrared shielding agents mainly include nano metals (such as commonly used nano silver), metal oxides (such as tin oxide system, silicon oxide, aluminum oxide, titanium oxide, etc.), nitrides (such as titanium nitride), and metal compounds (such as silicate system, tungstate system). Among them, silicon oxide, aluminum oxide, titanium oxide, and silicate have low transmittance in the visible light region and poor compatibility with resins, and are not suitable for films; while nano metals, nitrides, and tungstates are expensive, which will greatly increase the production cost of agricultural cooling film. In addition, the cooling effect of commonly used agricultural films is poor. When the ambient temperature exceeds 35°C, it cannot achieve a good cooling effect, and there is a problem of affecting the normal photosynthesis of crops.

[0005] Therefore, there is an urgent need to provide a low-cost agricultural cooling film that can achieve a good cooling effect in high temperature weather without affecting the normal photosynthesis of crops. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a tin oxide-based infrared shielding agent and an agricultural cooling film prepared using the same. The agricultural cooling film prepared using the tin oxide-based infrared shielding agent provided by the present invention can achieve a good cooling effect in high temperature weather without affecting the normal photosynthesis of crops.

[0007] The invention provides a tin oxide system infrared shielding agent.

[0008] Specifically, a tin oxide system infrared shielding agent, the general chemical formula of which is: (Sn 1-x M x ) 2 :F;

[0009] Among them, 0 <x≤0.9;

[0010] M includes one or any combination of Ga, In, Sb, Bi, Mo, W, La, and Yb;

[0011] O 2 :F is the doping of fluorine ions to replace part of the oxygen ions, and the doping amount of fluorine ions F / O satisfies 0 <F / O≤0.3。

[0012] Preferably, M includes one or any combination of Ga, Sb, and Mo; further preferably, M includes Sb and / or Mo.

[0013] Preferably, the particle size of the infrared shielding agent is 30-150nm. Within this particle size range, the infrared shielding agent has excellent infrared shielding performance and extremely high visible light transmittance. The agricultural cooling film made from it as a raw material has excellent cooling performance and high light transmittance, and has a good promoting effect on plant growth in hot weather.

[0014] The invention also provides a modified infrared shielding agent.

[0015] Specifically, a modified infrared shielding agent is obtained by modifying the above infrared shielding agent with a modifier, wherein the modifier is selected from one or more of phenolic resin, amino resin, alkyd resin, epoxy resin, acrylic resin, silane coupling agent, and titanate coupling agent. The modifier is used to modify the surface of the infrared shielding agent to achieve ultrafine crushing of the infrared shielding agent. The use of the modifier effectively improves the dispersibility of the crushed infrared shielding agent, so that the infrared shielding agent can be evenly dispersed in the film material, so that the film material has good uniformity and workability.

[0016] Preferably, the mass ratio of the infrared shielding agent to the modifier is (10-100):1; further preferably, the mass ratio of the infrared shielding agent to the modifier is (20-50):1.

[0017] The invention also provides a method for preparing the modified infrared shielding agent.

[0018] Specifically, the preparation method of the modified infrared shielding agent comprises the following steps:

[0019] The infrared shielding agent is mixed with a modifier and water, and ground to obtain a modified infrared shielding agent.

[0020] The invention also provides an agricultural cooling film.

[0021] Specifically, an agricultural cooling film comprises the following raw material components by weight:

[0022] 0.5-10 parts of the above modified infrared shielding agent and 80-99 parts of the polymer matrix.

[0023] Preferably, the polymer matrix is ​​selected from one or a combination of more than one of polyethylene, polyvinyl chloride, polypropylene, polyamide, polystyrene, polyvinylidene chloride, polyvinylidene fluoride, polycarbonate and polyurethane.

[0024] Preferably, the modified infrared shielding agent accounts for 1.0%-8.0% of the mass of the polymer matrix; further preferably, the modified infrared shielding agent accounts for 2.0%-8.0% of the mass of the polymer matrix; more preferably, the modified infrared shielding agent accounts for 3.0%-6.0% of the mass of the polymer matrix.

[0025] Preferably, the raw material components of the agricultural cooling film further include 0.05-4.5 parts of lubricant by weight.

[0026] Preferably, the lubricant is selected from one or more of stearic acid, calcium stearate, zinc stearate, glyceryl stearate, pentaerythritol stearate, polyethylene wax, oxidized polyethylene wax, and vinyl bisstearamide. The use of the lubricant can effectively improve the compatibility of the polymer matrix with other film materials, optimize the efficiency of film material mixing and the mechanical properties of the agricultural cooling film.

[0027] Preferably, the raw material components of the agricultural cooling film further include 0.02-2 parts of light stabilizer and 0.02-2 parts of antioxidant by weight. The introduction of the light stabilizer and the antioxidant can improve the weather resistance of the film material and extend the service life of the agricultural cooling film.

[0028] Preferably, the light stabilizer is selected from one or more of 2-(2-hydroxy-5-methylphenyl)benzotriazole, (2,2,6,6-tetramethyl-4-piperidinyl)imine, sebacate bis-2,2,6,6-tetramethylpiperidinol ester, 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol, and benzophenone.

[0029] Preferably, the antioxidant is selected from 2,4,6-tri-tert-butylphenol, antioxidant 1076, antioxidant CA, antioxidant 1010, antioxidant 168, and dilauryl thiodipropionate, or a combination of more than one of them.

[0030] The invention also provides a method for preparing the agricultural cooling film.

[0031] Specifically, a method for preparing an agricultural cooling film comprises the following steps:

[0032] The modified infrared shielding agent is mixed evenly with the polymer matrix and the remaining raw material components, and then granulated and blow-molded to obtain an agricultural cooling film.

[0033] More specifically, a method for preparing an agricultural cooling film comprises the following steps:

[0034] The modified infrared shielding agent, polymer matrix, lubricant, light stabilizer and antioxidant are uniformly mixed, granulated and blow-molded to obtain an agricultural cooling film.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The tin oxide-based infrared shielding agent provided by the present invention can effectively absorb infrared rays and has a high selective permeability to visible light. The agricultural cooling film prepared by using the tin oxide-based infrared shielding agent can effectively absorb the near-infrared part of sunlight to achieve a significant cooling effect, and has a high visible light transmittance and does not affect the normal photosynthesis of plants.

[0037] (2) The agricultural cooling film provided by the present invention has low cost, simple manufacturing process, no need for complicated procedures or difficult-to-operate equipment, and has good prospects for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a scanning electron microscope image of the infrared shielding agent of the tin oxide system prepared in Example 1;

[0039] Figure 2 This is the UV-visible-near infrared spectrum of the agricultural cooling film prepared in Example 6;

[0040] Figure 3 The curves of surface temperature variation with time for each group are shown in Figure 2. DETAILED DESCRIPTION

[0041] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0042] Unless otherwise specified, the raw materials, reagents or devices used in the following examples and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0043] Example 1

[0044] A tin oxide system infrared shielding agent, the general chemical formula of which is: (Sn 0.9 Sb 0.1 ) 2 :F, F / O=0.12.

[0045] The preparation method of the above-mentioned tin oxide system infrared shielding agent comprises the following steps:

[0046] Weigh 455.77g SnCl 4 ·5H 2 O, 438 g NaHCO 3 、29.65g SbCl 3 In a ball mill, add 13.00 g NH 4 F. Weigh 3700g of zirconia balls with a diameter of 5mm and add them to a ball mill. Mill at a speed of 300rpm for 1h. After the ball milling is completed, dry it and pass it through an 80-mesh sieve to obtain a precursor. The precursor is calcined at 550℃ in a muffle furnace for 2h. After completion, wash it with water 3 times, wash it with anhydrous ethanol once and dry it to obtain an infrared shielding agent (Sn0.9Sb0.1)O2:F of the tin oxide system. Its scanning electron microscope image is as follows Figure 1 As shown by Figure 1It can be seen that the infrared shielding agent of the tin oxide system prepared in this example is spherical particles with a central particle diameter of about 100 nm, good particle morphology and good dispersibility, and is very suitable for application in agricultural films.

[0047] A method for preparing a modified infrared shielding agent comprises the following steps:

[0048] Weigh 170 g of the above-mentioned tin oxide system infrared shielding agent, mix the infrared shielding agent with water in a weight ratio of 1:1 to form a slurry, add 0.8-1 mm zirconium oxide beads, sand grind in a sand mill, set the speed to 200 rpm, add 8 g of titanate coupling agent during the sand grinding process, and sand grind for 30 minutes. The sand-milled slurry is filter-filtered and dried to obtain a modified infrared shielding agent.

[0049] Example 2

[0050] A tin oxide system infrared shielding agent, the general chemical formula of which is: (Sn 0.7 Ga 0.3 ) 2 :F, F / O=0.20.

[0051] The preparation method of the above-mentioned tin oxide system infrared shielding agent comprises the following steps:

[0052] Weigh 81.80g SnCl 4 ·5H 2 O, 118 g NaHCO 3 、17.61g GaCl 3 In a ball mill, add 5.00 g NH 4 F. Weigh 1000g of zirconia balls with a diameter of 5mm and add them to a ball mill. Mill at a speed of 300rpm for 1h. After the ball milling is completed, dry it and pass it through an 80-mesh sieve to obtain a precursor. Calcine the precursor at 600℃ in a muffle furnace for 1h. After completion, wash it with water 3 times, wash it with anhydrous ethanol once and dry it to obtain an infrared shielding agent (Sn 0.7 Ga 0.3 ) 2 :F.

[0053] A method for preparing a modified infrared shielding agent comprises the following steps:

[0054] Weigh 56 g of the above-mentioned infrared shielding agent, mix the infrared shielding agent with water in a weight ratio of 1:1 to form a slurry, add 0.8-1 mm zirconium oxide beads, sand grind in a sand mill, set the speed to 200 rpm, add 5 g of silane coupling agent during the sand grinding process, and sand grind for 30 minutes. The sand-milled slurry is filter-filtered and dried to obtain a modified infrared shielding agent.

[0055] Example 3

[0056] A tin oxide system infrared shielding agent, the general chemical formula of which is: (Sn 0.97 La 0.03 ) 2 :F, F / O=0.14.

[0057] The preparation method of the above-mentioned tin oxide system infrared shielding agent comprises the following steps:

[0058] Weigh 680.14g SnCl 4 ·5H 2 O, 686 g NaHCO 3 , 22.28 g LaCl 3 7H 2 O in a ball mill, to which 20.00 g NH 4 F. Weigh 3000g of zirconia balls with a diameter of 5mm and add them to a ball mill. Mill at a speed of 450rpm for 2.5h. After the ball milling is completed, dry it and pass it through an 80-mesh sieve to obtain a precursor. Calcine the precursor at 750℃ in a muffle furnace for 1h. After completion, wash it with water 3 times, wash it with anhydrous ethanol once and dry it to obtain an infrared shielding agent (Sn 0.97 La 0.03 ) 2 :F.

[0059] A method for preparing a modified infrared shielding agent comprises the following steps:

[0060] Weigh 300 g of the above-mentioned tin oxide system infrared shielding agent, mix the infrared shielding agent with water in a weight ratio of 1:1 to form a slurry, add 0.8-1 mm zirconium oxide beads, sand grind in a sand mill, set the speed to 200 rpm, add 7 g of acrylic resin during the sand grinding process, and sand grind for 40 minutes. The sand-milled slurry is filter-filtered and dried to obtain a modified infrared shielding agent.

[0061] Example 4

[0062] A tin oxide system infrared shielding agent, the general chemical formula of which is: (Sn 0.99 Mo 0.01 ) 2 :F, F / O=0.14.

[0063] The preparation method of the above-mentioned tin oxide system infrared shielding agent comprises the following steps:

[0064] Weigh 694.16g SnCl 4 ·5H 2 O, 674 g NaHCO 3 、3.92g(NH 4 )2 MoO 4 In a ball mill, add 20.00 g NH 4 F. Weigh 3000g of zirconia balls with a diameter of 5mm and add them to a ball mill. Mill the balls at 450rpm for 2.5h. After the ball milling is completed, dry the balls and pass through an 80-mesh sieve to obtain a precursor. The precursor is calcined in a muffle furnace at 800℃ for 2h. After completion, wash the precursor with water three times, wash it with anhydrous ethanol once and dry it to obtain an infrared shielding agent (Sn 0.99 Mo 0.01 ) 2 :F.

[0065] A method for preparing a modified infrared shielding agent comprises the following steps:

[0066] Weigh 300 g of the above-mentioned infrared shielding agent, mix the infrared shielding agent with water in a weight ratio of 1:1 to form a slurry, add 0.8-1 mm zirconium oxide beads, sand grind in a sand mill, set the speed to 200 rpm, add 7 g of acrylic resin during the sand grinding process, and sand grind for 40 minutes. The sand-milled slurry is filtered and dried to obtain a modified infrared shielding agent.

[0067] Example 5

[0068] A tin oxide system infrared shielding agent, the general chemical formula of which is: (Sn 0.89 Sb 0.1 Mo 0.01 ) 2 :F, F / O=0.12.

[0069] The preparation method of the above-mentioned tin oxide system infrared shielding agent comprises the following steps:

[0070] The preparation method of the infrared shielding agent has the following steps:

[0071] Weigh 450.70g SnCl 4 ·5H 2 O, 438 g NaHCO 3 、29.65g SbCl 3 、2.82g(NH 4 ) 2 MoO 4 In a ball mill, add 13.00 g NH 4 F. Weigh 3700g of zirconia balls with a diameter of 5mm and add them to a ball mill. Mill at a speed of 300rpm for 1h. After the ball milling is completed, dry it and pass it through an 80-mesh sieve to obtain a precursor. Calcine the precursor at 550℃ in a muffle furnace for 2h. After completion, wash it with water 3 times, wash it with anhydrous ethanol once and dry it to obtain an infrared shielding agent (Sn 0.89 Sb0.1 Mo 0.01 ) 2 :F.

[0072] A method for preparing a modified infrared shielding agent comprises the following steps:

[0073] Weigh 200 g of the above-mentioned tin oxide system infrared shielding agent, mix the infrared shielding agent with water in a weight ratio of 1:1 to form a slurry, add 0.8-1 mm zirconium oxide beads, sand grind in a sand mill, set the speed to 200 rpm, add 4 g of titanate coupling agent and 4 g of acrylic resin during the sand grinding process, sand grind for 30 min, filter press the sand milled slurry, and dry it to obtain a modified infrared shielding agent.

[0074] Comparative Example 1

[0075] A SnO 2 The preparation method is as follows:

[0076] Weigh 506.41g SnCl 4 ·5H 2 O, 438 g NaHCO 3 In a ball mill, weigh 3700g of zirconia balls with a diameter of 5mm and add them to the ball mill. Mill at a speed of 300rpm for 1h. After the ball milling is completed, dry it and pass it through an 80-mesh sieve to obtain a precursor. The precursor is calcined in a muffle furnace at 550℃ for 2h. After completion, wash it with water 3 times, wash it with anhydrous ethanol once and dry it to obtain SnO 2 .

[0077] A modified SnO 2 The preparation method is as follows:

[0078] Weigh the above SnO 2 170g of SnO was mixed with water in a weight ratio of 1:1 to form a slurry, 0.8-1mm zirconium oxide beads were added, and the mixture was sand-milled in a sand mill with a speed of 200rpm. During the sand-milling process, 8g of titanate coupling agent was added, and the sand-milling time was 30min. The sand-milled slurry was filtered and dried to obtain modified SnO 2 .

[0079] Example 6

[0080] A method for preparing an agricultural cooling film is as follows:

[0081] The modified infrared shielding agent prepared in Example 1 was mixed with 20 g (2,2,6,6-tetramethyl-4-piperidinyl) imine, 30 g antioxidant 168, 50 g polyethylene wax and 600 g polyethylene using a high-speed mixer for 5 min. The mixed material was extruded and granulated by an extruder at a temperature of 140 ° C and a screw speed of 200 r / min to obtain a masterbatch. The masterbatch was then evenly mixed with 5200 g polyethylene and blown by a blow molding machine to obtain an agricultural cooling film, and the film thickness was controlled to be 8 filaments.

[0082] Figure 2 This is the UV-visible-near infrared spectrum of the agricultural cooling film prepared in Example 6. The agricultural cooling film has a lower transmittance in the ultraviolet region (300-400nm) and the near infrared region (780-2500nm), and a higher transmittance in the visible light region (400-780nm). This shows that the agricultural cooling film has a selective transmittance to natural light, and can effectively absorb infrared rays that cause the ground temperature to rise, without affecting the transmittance of visible light required for plant growth.

[0083] Example 7

[0084] A method for preparing an agricultural cooling film is as follows:

[0085] Using a high-speed mixer, the modified infrared shielding agent prepared in Example 2 was mixed with 60 g of bis-2,2,6,6-tetramethylpiperidinol sebacate, 50 g of antioxidant 1076, 120 g of glyceryl stearate, and 2600 g of polypropylene. The mixing time was 5 min, and the mixed material was extruded and granulated by an extruder at a temperature of 140 ° C and a screw speed of 300 r / min to obtain a masterbatch; then the masterbatch was evenly mixed with 3000 g of polypropylene, and a warming film was obtained by blow molding with a blow molding machine, and the film thickness was controlled to be 12 filaments.

[0086] Example 8

[0087] A method for preparing an agricultural cooling film is as follows:

[0088] Using a high-speed mixer, the modified infrared shielding agent prepared in Example 3 was mixed with 80 g of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol, 15 g of antioxidant CA, 20 g of oxidized polyethylene wax, and 1500 g of polyethylene. The mixing time was 5 min, and the mixed material was extruded and granulated by an extruder at an extrusion temperature of 160 ° C and a screw speed of 300 r / min to obtain a masterbatch; then the masterbatch was evenly mixed with 4500 g of polyethylene, and a warming film was obtained by blow molding with a blow molding machine, and the film thickness was controlled to be 10 filaments.

[0089] Example 9

[0090] A method for preparing an agricultural cooling film is as follows:

[0091] The modified infrared shielding agent obtained in Example 4 was mixed with 80 g of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol, 15 g of antioxidant CA, 20 g of oxidized polyethylene wax, and 1500 g of polyethylene using a high-speed mixer. The mixing time was 5 min, and the mixed material was extruded and granulated by an extruder at an extrusion temperature of 160 ° C and a screw speed of 300 r / min to obtain a masterbatch; the masterbatch was then evenly mixed with 4500 g of polyethylene, and a warming film was obtained by blow molding with a blow molding machine, and the film thickness was controlled to be 10 filaments.

[0092] Example 10

[0093] A method for preparing an agricultural cooling film is as follows:

[0094] Using a high-speed mixer, the modified infrared shielding agent prepared in Example 5 was mixed with 53 g of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol, 10 g of antioxidant CA, 13 g of oxidized polyethylene wax, and 2000 g of polyethylene. The mixing time was 5 min, and the mixed material was extruded and granulated by an extruder at an extrusion temperature of 160 ° C and a screw speed of 300 r / min to obtain a masterbatch; then the masterbatch was evenly mixed with 2960 g of polyethylene, and a warming film was obtained by blow molding with a blow molding machine, and the film thickness was controlled to be 10 filaments.

[0095] Comparative Example 2

[0096] A method for preparing an agricultural cooling film is as follows:

[0097] The modified SnO prepared in Comparative Example 1 was mixed with a high-speed mixer. 2 It was mixed with 20g (2,2,6,6-tetramethyl-4-piperidinyl)imine, 30g antioxidant 168, 50g polyethylene wax and 600g polyethylene for 5min. The mixed material was extruded and granulated by an extruder at a temperature of 140°C and a screw speed of 200r / min to obtain a masterbatch. The masterbatch was then evenly mixed with 5200g polyethylene and a film was obtained by blow molding with a blow molding machine. The film thickness was controlled to be 8 filaments.

[0098] Comparative Example 3

[0099] A method for preparing an agricultural cooling film is as follows:

[0100] Using a high-speed mixer, the infrared shielding agent of the tin oxide system prepared in Example 1 was mixed with 20g (2,2,6,6-tetramethyl-4-piperidinyl) imine, 30g antioxidant 168, 50g polyethylene wax, and 600g polyethylene. The mixing time was 5min. The mixed material was extruded and granulated by an extruder at a temperature of 140°C and a screw speed of 200r / min to obtain a masterbatch. The masterbatch was then evenly mixed with 5200g polyethylene and blown by a blow molding machine to obtain an agricultural cooling film, and the film thickness was controlled to be 8 filaments.

[0101] Effect test

[0102] (1) The agricultural cooling film prepared by Examples 6-10 and Comparative Examples 1-3 was used for the experiment. The specific operation is as follows: select adjacent greenhouse farmland in an east-west direction, each farmland is 4.5 meters wide, 15 meters long, and the height of the greenhouse is 3.5 meters. Comparative tests were conducted on the agricultural cooling films prepared by Covering Examples 6-10 and Comparative Examples 1-3, and a temperature probe was placed in the middle of each farmland. A clear day was selected to test the surface temperature in the greenhouse at 1 pm (the temperature of three different places in the greenhouse was tested and the average value was calculated). In order to ensure the accuracy of the experimental data, the experimental group (each embodiment and comparative example) and the control group (not covered with film) both selected two adjacent farmlands that were not affected by other greenhouses for the experiment. The experiment can be carried out in batches. The test results are shown in Table 1.

[0103] Table 1

[0104] Group Surface temperature in the shed Adjacent surface temperature without film covering Example 6 42.1℃ 47.9℃ Example 7 43.3℃ 48.0℃ Example 8 43.9℃ 49.2℃ Example 9 44.2℃ 50.4℃ Example 10 43.1℃ 49.7℃ Comparative Example 2 46.0℃ 48.9℃ Comparative Example 3 45.5℃ 49.0℃

[0105] It can be seen from Table 1 that the agricultural cooling film provided by the embodiment of the present invention can significantly reduce the surface temperature in the greenhouse, and its effect is significantly better than that of the agricultural film not covered and the agricultural film provided by Comparative Examples 2 and 3.

[0106] (2) Test the surface temperature of farmland covered with ordinary PE agricultural film, covered with Example 6, and not covered with agricultural film at different time points in one day, and draw a curve of surface temperature change over time. The specific operation is as follows: select three adjacent greenhouse farmlands in an east-west direction, each of which is 4.5 meters wide, 15 meters long, and 3.5 meters high. Cover the greenhouse with no film, ordinary PE agricultural film, and agricultural cooling film provided in Example 6, respectively, and place a temperature probe in the middle of each farmland. Select a sunny day and record the surface temperature of the three farmlands at different time points in one day. Figure 3 The graphs of the surface temperature of each group changing with time show that, compared with the surface without agricultural film and the surface covered with ordinary PE agricultural film, the agricultural cooling film provided in Example 6 of the present invention is applied to greenhouse farmland, which can achieve a significant cooling effect, especially during the high temperature period during the day.

[0107] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A tin oxide-based infrared shielding agent, characterized in that: Its chemical formula is: (Sn 1-x M x )O2:F; Among them, 0 <x≤0.9; M includes one or any combination of Ga, In, Sb, Bi, Mo, W, La, and Yb; O2:F is doped with fluorine ions to replace some oxygen ions, and the doping amount of fluorine ions F / O satisfies 0 <F / O≤0.3。 2. The infrared shielding agent according to claim 1, characterized in that The particle size of the infrared shielding agent is 30-150 nm.

3. A modified infrared shielding agent, characterized in that: The infrared shielding agent according to claim 1 or 2 is modified by a modifier, wherein the modifier is selected from one or more of phenolic resin, amino resin, alkyd resin, epoxy resin, acrylic resin, silane coupling agent and titanate coupling agent.

4. The modified infrared shielding agent according to claim 3, characterized in that The mass ratio of the infrared shielding agent to the modifier is (10-100):

1.

5. The method for preparing the modified infrared shielding agent according to claim 3 or 4, characterized in that: The following steps are involved: The infrared shielding agent is mixed with a modifier and water, and ground to obtain a modified infrared shielding agent.

6. An agricultural cooling film, characterized in that: By weight, it includes the following raw material components: 0.5-10 parts of the modified infrared shielding agent according to claim 3 or 4 and 80-99 parts of a polymer matrix.

7. The agricultural cooling film according to claim 6, characterized in that: The polymer matrix is ​​selected from one or a combination of polyethylene, polyvinyl chloride, polypropylene, polyamide, polystyrene, polyvinylidene chloride, polyvinylidene fluoride, polycarbonate, and polyurethane.

8. The agricultural cooling film according to claim 6 or 7, characterized in that: In parts by weight, the raw material components of the agricultural cooling film also include 0.05-4.5 parts of lubricant; the lubricant is selected from one or a combination of stearic acid, calcium stearate, zinc stearate, glyceryl stearate, pentaerythritol stearate, polyethylene wax, oxidized polyethylene wax, and vinyl bisstearamide.

9. The agricultural cooling film according to claim 6 or 7, characterized in that: In parts by weight, the raw material components of the agricultural cooling film also include 0.02-2 parts of light stabilizer and 0.02-2 parts of antioxidant; the light stabilizer is selected from one or more combinations of 2-(2-hydroxy-5-methylphenyl)benzotriazole, (2,2,6,6-tetramethyl-4-piperidinyl)imine, sebacate bis-2,2,6,6-tetramethylpiperidinol ester, 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol, and benzophenone; the antioxidant is selected from one or more combinations of 2,4,6-tri-tert-butylphenol, antioxidant 1076, antioxidant CA, antioxidant 1010, antioxidant 168, and dilauryl thiodipropionate.

10. The method for preparing the agricultural cooling film according to any one of claims 6 to 9, characterized in that: The following steps are involved: The modified infrared shielding agent according to claim 3 or 4 is mixed evenly with a polymer matrix and remaining raw material components, and then granulated and blow-molded to obtain an agricultural cooling film.

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