Infrared screening agent and agricultural cooling film prepared from same

Abstract

The invention belongs to the technical field of agricultural films, and discloses an infrared screening agent and an agricultural cooling film prepared from the infrared screening agent. The general chemical formula of the infrared screening agent is Ax (W1-y, By) O3, wherein 0 lt; x is less than or equal to 0.33, 0lt; y < = 0.1; a comprises one or a combination of any more of Na, K and Rb; and B comprises one or a combination of Cr and Mo. The infrared screening agent provided by the invention can effectively absorb infrared rays and has relatively high selective permeability to visible light. The agricultural cooling film prepared from the composite material can effectively absorb near infrared rays in sunlight to achieve an obvious cooling effect, has high visible light transmittance, and does not influence normal photosynthesis of plants. The agricultural cooling film provided by the invention is simple and convenient in manufacturing process, does not need complex procedures or equipment which is difficult to operate, and has good popularization and application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural films, and in particular relates to an infrared shielding agent and an agricultural cooling film prepared by using the infrared shielding agent. 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 and harm of high temperature on crops is generally most obvious in rice. The sensitive period of damage is the flowering-milky period of rice. The damage to rice is manifested by the premature aging and yellowing of the last three functional leaves, shortened filling period, decreased dry grain weight, and increased rate of barren grains. The filling period of early rice, early-mid rice, and hybrid rice in the south of the Yangtze River is in midsummer, and they are often harmed by it. High temperature can also cause flowers to fall from vegetables, reduce the fruit setting rate, and have an adverse effect on the growth and development of cucumbers, eggplants, beans, etc. Potatoes degenerate after being damaged, and the tubers become smaller. Fruit trees and forests can also cause burns. In view of the high temperature in summer, especially in tropical areas, it is a particularly important task to cool down fruit trees in farmland.

[0004] Agricultural cooling film is a film that can cool crops, but the cooling effect of the 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 an 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 an infrared shielding agent and an agricultural cooling film prepared using the same. The agricultural cooling film prepared using the 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 an infrared shielding agent.

[0008] Specifically, an infrared shielding agent, the general chemical formula of which is: x (W 1-y ,B y )O3;

[0009] Among them, 0 <x≤0.33,0<y≤0.1;

[0010] A includes one or any combination of Na, K, and Rb;

[0011] B includes Cr and Mo or a combination thereof.

[0012] Preferably, the particle size of the infrared shielding agent is 10-100 nm. 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 the infrared shielding agent as a raw material has excellent cooling performance and high light transmittance, and has a good promoting effect on plant growth in hot weather.

[0013] The invention also provides an agricultural cooling film.

[0014] Specifically, an agricultural cooling film comprises the following raw material components by weight:

[0015] 0.1-10 parts of infrared shielding agent, 0.001-0.5 parts of modifier and 80-99 parts of polymer matrix.

[0016] Preferably, 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.

[0017] 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.

[0018] Preferably, the raw material components of the agricultural cooling film further include 0.05-4.5 parts of lubricant by weight.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] The invention also provides a method for preparing the agricultural cooling film.

[0024] Specifically, a method for preparing an agricultural cooling film comprises the following steps:

[0025] The infrared shielding agent and the modifier are mixed and ground to obtain the modified infrared shielding agent; then the polymer matrix and the remaining raw material components are added, mixed evenly, granulated and blown to obtain the agricultural cooling film.

[0026] More specifically, a method for preparing an agricultural cooling film comprises the following steps:

[0027] The infrared shielding agent, the modifier and water are mixed, ground and dried to obtain the modified infrared shielding agent; then a polymer matrix, a lubricant, a light stabilizer and an antioxidant are added, mixed evenly, granulated and blown to obtain an agricultural cooling film.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The 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 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.

[0030] (2) The agricultural cooling film provided by the present invention has a simple manufacturing process, does not require complicated procedures or difficult-to-operate equipment, and has good prospects for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a scanning electron microscope image of the infrared shielding agent prepared in Example 1;

[0032] Figure 2 This is the UV-visible-near infrared spectrum of the agricultural cooling film prepared in Example 5;

[0033] Figure 3 The curves of surface temperature variation with time for each group are shown in Figure 2. DETAILED DESCRIPTION

[0034] 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 noted that the following embodiments do not limit the protection scope of the present invention.

[0035] 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.

[0036] Example 1

[0037] An infrared shielding agent, whose chemical formula is Rb 0.33 (W 0.99 Cr 0.01 )O3.

[0038] The preparation method of the infrared shielding agent comprises the following steps:

[0039] 62.40g H2C2O4·2H2O and 326.55g Na2WO4·2H2O were weighed and placed in a ball mill containing 900g zirconium oxide beads with a diameter of 3-5mm. Subsequently, they were transferred to a ball mill and ball milled at a speed of 400rpm for 3h to obtain a yellow product. The yellow product was washed with water 3 times, washed with anhydrous ethanol once and dried to obtain a precursor. Then, the precursor and 38.10g Rb2CO3 and 3.26g Cr2CO3 were reduced with 5% H2 / N2 at 650℃ for 5h to obtain an infrared shielding agent Rb 0.33 (W 0.99 Cr 0.01 )O3. Its scanning electron microscope image is as follows Figure 1 As shown by Figure 1 It can be seen that the infrared shielding agent Rb provided in this embodiment 0.33 (W 0.99 Cr 0.01 )The single particle size of O3 is about 50nm, with little agglomeration and good dispersion, making it suitable for agricultural film.

[0040] Example 2

[0041] An infrared shielding agent, whose chemical formula is Rb 0.33 (W 0.97 Mo 0.03 )O3.

[0042] The preparation method of the infrared shielding agent comprises the following steps:

[0043] 123.55g H2C2O4·2H2O and 633.64g Na2WO4·2H2O were weighed and placed in a ball mill containing 1000g zirconium oxide beads with a diameter of 3-5mm. Subsequently, they were transferred to a ball mill and ball milled at a speed of 450rpm for 3h to obtain a yellow product. These products were washed with water 3 times, washed with anhydrous ethanol once and dried to obtain a precursor. Then, the precursor was uniformly mixed with 75.46g Rb2CO3 and 11.65g (NH4)2MoO4, and reduced with 5% H2 / N2 at 700℃ for 5h to obtain an infrared shielding agent Rb 0.33 (W 0.97 Mo 0.03 )O3.

[0044] Example 3

[0045] An infrared shielding agent, the chemical formula of which is K 0.30 (W 0.99 Cr 0.01 )O3.

[0046] The preparation method of the infrared shielding agent comprises the following steps:

[0047] 81.12g H2C2O4·2H2O and 424.52g Na2WO4·2H2O were weighed and placed in a ball mill containing 1000g zirconium oxide beads with a diameter of 3-5mm. Subsequently, they were transferred to a ball mill and ball milled at a speed of 300rpm for 4h to obtain a yellow product. The yellow product was washed with water 3 times, washed with anhydrous ethanol once and dried to obtain a precursor. Then, the precursor was uniformly mixed with 26.95g K2CO3 and 4.24g Cr2CO3, and reduced with 5% H2 / N2 at 800℃ for 1h to obtain an infrared shielding agent K 0.30 (W 0.99 Cr 0.01 )O3.

[0048] Example 4

[0049] An infrared shielding agent, the chemical formula of which is (Na 0.10 R 0.23 )(W 0.99 Cr 0.01 )O3.

[0050] The preparation method of the infrared shielding agent comprises the following steps:

[0051] 124.80g H2C2O4·2H2O and 653.10g Na2WO4·2H2O were weighed and placed in a ball mill containing 1000g zirconium oxide beads with a diameter of 3-5mm. Subsequently, they were transferred to a ball mill and ball milled at a speed of 500rpm for 3h to obtain a yellow product. These products were washed with water 3 times, washed with anhydrous ethanol once and dried to obtain a precursor. Then, the precursor was uniformly mixed with 53.12g Rb2CO3, 10.60g Na2CO3, and 6.52g Cr2CO3, and reduced with 5% H2 / N2 at 700℃ for 1h to obtain an infrared shielding agent (Na 0.10 R 0.23 )(W 0.99 Cr 0.01 )O3.

[0052] Comparative Example 1

[0053] An infrared shielding agent, whose chemical formula is Rb 0.33 WO3.

[0054] The preparation method of the infrared shielding agent comprises the following steps:

[0055] 62.40 g H2C2O4·2H2O and 329.85 g Na2WO4·2H2O were weighed and placed in a ball mill containing 900 g zirconia beads with a diameter of 3-5 mm. Subsequently, they were transferred to a ball mill and ball milled at 400 rpm for 3 h to obtain a yellow product. The yellow product was washed with water 3 times, washed with anhydrous ethanol once and dried to obtain a precursor. Then, the precursor and 38.10 g Rb2CO3 were reduced with 5% H2 / N2 at 650 ° C for 5 h to obtain Rb 0.33 WO3.

[0056] Example 5

[0057] A method for preparing an agricultural cooling film, the steps are as follows:

[0058] (1) Weighing 180 g of the infrared shielding agent prepared in Example 1, mixing the infrared shielding agent with water in a weight ratio of 1:1 to form a slurry, adding 0.8-1 mm zirconium oxide beads, sand grinding in a sand mill, setting the speed to 200 rpm, adding 9 g of titanate coupling agent during the sand grinding process, sand grinding time 15 min, and the sand milled slurry was filtered and dried to obtain a modified infrared shielding agent;

[0059] (2) Using a high-speed mixer, the modified infrared shielding agent was mixed with 30 g of 2-(2-hydroxy-5-methylphenyl)benzotriazole, 30 g of antioxidant 1076, 60 g of polyethylene wax, and 700 g of polyethylene. The mixing time was 5 min. The mixed material was extruded and granulated by an extruder at an extrusion temperature of 140° C. and a screw speed of 200 r / min to obtain a masterbatch. The masterbatch was then uniformly mixed with 5000 g of polyethylene and blow-molded by a blow molding machine to obtain an agricultural cooling film, and the film thickness was controlled to be 8 filaments.

[0060] Figure 2 This is the UV-visible-near infrared spectrum of the agricultural cooling film prepared in Example 5. The 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 provided by the present invention 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.

[0061] Example 6

[0062] A method for preparing an agricultural cooling film, the steps are as follows:

[0063] (1) Weigh 300 g of the infrared shielding agent prepared in Example 2, 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 grinder, set the speed to 200 rpm, add 6 g of epoxy resin during the sand grinding process, sand grind for 40 min, filter press the sand grinded slurry, and dry it to obtain a modified infrared shielding agent;

[0064] (2) Using a high-speed mixer, the modified infrared shielding agent was mixed with 60 g of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol, 10 g of antioxidant 1010, 10 g of oxidized polyethylene wax, and 1300 g of polyethylene. The mixing time was 5 min. 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 uniformly mixed with 4300 g of polyethylene, and an agricultural cooling film was obtained by blow molding with a blow molding machine, and the film thickness was controlled to be 8 filaments.

[0065] Example 7

[0066] A method for preparing an agricultural cooling film, the steps are as follows:

[0067] (1) Weighing 360 g of the infrared shielding agent prepared in Example 3, mixing the infrared shielding agent with water in a weight ratio of 1:1 to form a slurry, adding 0.8-1 mm zirconium oxide beads, sand grinding in a sand mill, setting the speed to 200 rpm, adding 5 g of silane coupling agent during the sand grinding process, sand grinding time 30 min, and the sand milled slurry was filter pressed and dried to obtain a modified infrared shielding agent;

[0068] (2) Using a high-speed mixer, the modified infrared shielding agent was mixed with 60 g (2,2,6,6-tetramethyl-4-piperidinyl) imine, 60 g antioxidant 168, 120 g stearyl ester, and 3600 g polypropylene. The mixing time was 5 min. The mixed material was extruded and granulated by an extruder at an extrusion temperature of 140°C and a screw speed of 300 r / min to obtain a masterbatch. The masterbatch was then uniformly mixed with 2000 g polypropylene and blow-molded by a blow molding machine to obtain an agricultural cooling film. The film thickness was controlled to be 10 filaments.

[0069] Comparative Example 2

[0070] A method for preparing an agricultural cooling film, the steps are as follows:

[0071] (1) Weigh 180 g of Rb prepared in Comparative Example 1 0.33 WO3 was mixed with water in a weight ratio of 1:1 to form a slurry, and 0.8-1 mm zirconium oxide beads were added. The slurry was sanded in a sand mill with a speed of 200 rpm. During the sand milling process, 9 g of titanate coupling agent was added. The sand milling time was 15 min. The sand milled slurry was filtered and dried to obtain modified Rb 0.33 WO3;

[0072] (2) Using a high-speed mixer, the modified Rb 0.33 WO3 was mixed with 30g 2-(2-hydroxy-5-methylphenyl)benzotriazole, 30g antioxidant 1076, 60g polyethylene wax and 700g 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 uniformly mixed with 5000g polyethylene and a film was obtained by blow molding with a blow molding machine. The film thickness was controlled to be 8 filaments.

[0073] Comparative Example 3

[0074] A method for preparing an agricultural cooling film, the steps are as follows:

[0075] (1) Weigh 180 g of the infrared shielding agent prepared in Example 1, and use a high-speed mixer to mix the infrared shielding agent with 30 g of 2-(2-hydroxy-5-methylphenyl)benzotriazole, 30 g of antioxidant 1076, 60 g of polyethylene wax, and 700 g of polyethylene. The mixing time is 5 min. The mixed material is extruded and granulated by an extruder at an extrusion temperature of 140° C. and a screw speed of 200 r / min to obtain a masterbatch. Then, the masterbatch is uniformly mixed with 5000 g of polyethylene, and an agricultural cooling film is obtained by blow molding by a blow molding machine, and the film thickness is controlled to be 8 filaments.

[0076] Effect test

[0077] (1) The agricultural cooling film prepared by Examples 5, 6, 7 and Comparative Examples 2 and 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. Compare the surface temperatures of the agricultural cooling films prepared by Examples 5, 6, 7 and Comparative Examples 2 and 3 and those not covered by the film, respectively, and place a temperature probe in the middle of the test farmland. Select a sunny day and test the surface temperature in the greenhouse at 1 pm (test the temperature in three different places in the greenhouse and calculate the average value). 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 select two adjacent farmlands that are not affected by other greenhouses for the experiment, and the experiment can be carried out in batches. The test results are shown in Table 1.

[0078] Table 1

[0079] Group Surface temperature in the shed Adjacent surface temperature without film covering Example 5 42.5℃ 48.7℃ Example 6 40.3℃ 48.0℃ Example 7 42.7℃ 48.6℃ Comparative Example 2 46.5℃ 50.7℃ Comparative Example 3 44.5℃ 49.0℃

[0080] 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.

[0081] (2) Test the surface temperature of farmland covered with ordinary PE agricultural film, covered with the agricultural cooling film provided in Example 5, and not covered with agricultural film at different time points in one day, and draw a curve of the change of surface temperature 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 5, 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 group not covered with agricultural film and the group covered with ordinary PE agricultural film, the agricultural cooling film provided in Example 5 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.

[0082] 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. An infrared shielding agent, characterized in that The general chemical formula of the infrared shielding agent is: A x (W 1-y ,B y )O3; where 0 <x≤0.33,0<y≤0.1; A includes one or any combination of Na, K, and Rb; B includes Cr and Mo or a combination thereof.

2. The infrared shielding agent according to claim 1, characterized in that The particle size of the infrared shielding agent is 10-100 nm.

3. An agricultural cooling film, characterized in that: By weight, it includes the following raw material components: 0.1-10 parts of the infrared shielding agent according to claim 1 or 2, 0.001-0.5 parts of a modifier and 80-99 parts of a polymer matrix.

4. The agricultural cooling film according to claim 3, characterized in that: The modifier is selected from one or a combination of phenolic resin, amino resin, alkyd resin, epoxy resin, acrylic resin, silane coupling agent or titanate coupling agent.

5. The agricultural cooling film according to claim 3, 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.

6. The agricultural cooling film according to any one of claims 3 to 5, characterized in that: The raw material components of the agricultural cooling film also include 0.05-4.5 parts of lubricant by weight.

7. The agricultural cooling film according to claim 6, characterized in that: 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.

8. The agricultural cooling film according to any one of claims 3 to 5, characterized in that: The raw material components of the agricultural cooling film further include 0.02-2 parts of light stabilizer and / or 0.02-2 parts of antioxidant by weight.

9. The agricultural cooling film according to claim 8, characterized in that: The light stabilizer is selected from one or more of 2-(2-hydroxy-5-methylphenyl)benzotriazole, (2,2,6,6-tetramethyl-4-piperidinyl)imine, bis-2,2,6,6-tetramethylpiperidinol sebacate, 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol, and benzophenone; the antioxidant is selected from one or more 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 3 to 9, characterized in that: The following steps are involved: The infrared shielding agent and the modifier are mixed and ground to obtain the modified infrared shielding agent; then the polymer matrix and the remaining raw material components are added, mixed evenly, granulated and blown to obtain the agricultural cooling film.

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