Forward scattering light heat insulation film based on multi-frequency resonance effect and preparation method and application thereof

Abstract

The invention relates to a forward scattering light heat insulation film based on a multi-frequency resonance effect and a preparation method and application thereof, and belongs to the technical field of heat insulation films. In order to solve the problems that an existing agricultural film cannot provide scattered light for plants and the like, the invention provides a forward scattering light heat insulation film containing light regulation particles, a base material and other auxiliaries. Functional light regulation and control particles with non-uniform particle sizes are introduced into the agricultural film, and the sunlight propagation path is changed by the film according to the multi-frequency resonance effect of the non-uniform particles and different forward scattering capacities on different wavebands of sunlight, so that scattered light in a greenhouse is effectively increased, plants are illuminated more uniformly, and the yield of the plants is improved. And the photosynthetic area of plants is effectively increased. Meanwhile, the functional light control particles can effectively reduce the temperature in the greenhouse by absorbing the near-infrared wavelength of sunlight. The single-layer film structure of the forward scattering light heat insulation film has the advantages of low cost, simple process and easiness in large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal insulation films, and in particular relates to a forward scattered light thermal insulation film based on a multi-frequency resonance effect, and a preparation method and application thereof. Background Art

[0002] Greenhouses play a vital role in agricultural production. They can protect crops from extreme weather conditions such as strong winds, low temperatures, heavy rains and insect pests, thereby providing a stable and suitable growth environment for crops to improve crop production efficiency and quality. Greenhouse film is an important component of the greenhouse. It has high light transmittance and can transmit sunlight, which is essential for plant photosynthesis. At the same time, greenhouse film provides an ideal growth environment for crops in the greenhouse through its various functions and characteristics, thereby improving crop yield and quality.

[0003] But the traditional greenhouse film is a smooth transmissive film, similar to glass, which can only provide direct light for photosynthetic plants. In sunny areas or countries, the presence of the sun's nearly parallel light and the sun's high angle will cause the plant to receive only light from the upper part of the upper leaves of the sun's rays. As a result, the plant casts a large shadow, which may cause most of its leaves to receive minimal or no light. As a result, the plant cannot fully utilize the sunlight for photosynthesis. Scattered light is more evenly distributed in the greenhouse than direct light, and can evenly distribute light into the plant canopy, reaching more parts of the plant, effectively increasing the photosynthetic area of ​​the plant, and improving photosynthetic efficiency, thereby promoting plant growth. In addition, the temperature in the greenhouse in summer is usually much higher than the normal temperature for plant growth. The high temperature heat stress brought by the greenhouse will enhance the transpiration of the plant, making it impossible for the plant to grow normally. Therefore, it is urgent to develop a new agricultural film material that can change the original direct light of the sunlight into scattered light and can also play a heat-insulating role to reduce the high temperature heat stress of the greenhouse. Summary of the invention

[0004] In order to solve the problem that existing agricultural films cannot provide scattered light for plants, resulting in the inability of plants to fully utilize sunlight and causing high temperature heat stress in summer or high temperature areas, the present invention provides a forward scattered light thermal insulation film based on multi-frequency resonance effect and a preparation method and application thereof.

[0005] The technical solution of the present invention:

[0006] A forward scattered light heat-insulating film based on a multi-frequency resonance effect contains the following components in parts by mass: 0.1 to 3 parts of light-regulating particles, 50 to 75 parts of a base material, 20 to 40 parts of a solvent, 0.1 to 1 part of a leveling agent, 0.1 to 1 part of a dispersant, 0.1 to 1 part of a defoaming agent, 0.1 to 1 part of a wetting agent, 1 to 5 parts of a film-forming aid, 0.1 to 1 part of an anti-sagging aid and 0.1 to 1 part of a thickener; the light-regulating particles are non-uniform particles with a particle size distribution range of 10 to 100 nm.

[0007] Furthermore, the light-regulating particles include one or a combination of ATO particles, GTO particles, ITO particles or AZO particles.

[0008] Furthermore, the light-regulating particles are a combination of ATO particles and GTO particles, or a combination of ITO particles and GTO particles, or a combination of ATO particles and AZO particles, or a combination of ITO particles and AZO particles.

[0009] Furthermore, the base material is acrylic resin; the solvent is deionized water; the leveling agent is one or a combination of carboxymethyl cellulose or silicone leveling agents; the dispersant is one or a combination of sodium tripolyphosphate, sodium hexametaphosphate, sodium silicate or modified polyether dispersants; the defoamer is one or a combination of silicone defoamers; the wetting agent is one or a combination of butyl naphthalene sulfonate sodium salt, sodium dodecyl sulfate, a condensate of fatty alcohol and ethylene oxide or an alcohol ether wetting agent; the film-forming aid is one or a combination of alcohol esters, alcohols, alcohol ether esters or alcohol ether film-forming aids; the anti-sagging aid is BYK420 anti-sagging aid; the thickener is one or a combination of cellulose ether, polyurethane thickener or polyacrylate.

[0010] Furthermore, the surface of the forward scattered light heat-insulating film is also coated with a hydrophobic layer, so that the film has a self-cleaning effect, thereby avoiding the reduction of light conversion effect due to dust accumulation.

[0011] Furthermore, the hydrophobic layer on the surface of the forward scattered light heat insulation film is a hydrophobic material polytetrafluoroethylene coated on the surface of the forward scattered light heat insulation film by spraying, scraping, flow coating or brushing.

[0012] A method for preparing a forward scattered light heat-insulating film based on a multi-frequency resonance effect comprises the following steps:

[0013] Step 1: sequentially mixing and stirring the solvent, the leveling agent, the dispersant, the defoaming agent, the wetting agent and the light-regulating particles to obtain a mixed system I;

[0014] Step 2: adding a base material and a film-forming aid to the obtained mixed system I, mixing and stirring to obtain a mixed system II;

[0015] Step 3, adding an anti-sagging agent and a thickener to the obtained mixed system II, mixing and stirring to obtain a mixed system III;

[0016] Step 4: Filter the obtained mixed system III and spray it on a transparent film, and then dry it at room temperature to obtain a forward scattered light heat insulation film based on the multi-frequency resonance effect.

[0017] Furthermore, the mixing and stirring speed in step 1 is 400-600 rpm / min; the mixing and stirring speeds in step 2 and step 3 are both 600-1000 rpm / min.

[0018] Furthermore, the mixed system III in step 4 is filtered using a 100-mesh double-layer filter, and the spraying thickness is 150 to 300 μm.

[0019] The invention discloses an application of a forward scattered light heat insulation film based on a multi-frequency resonance effect in the field of agricultural films.

[0020] Beneficial effects of the present invention:

[0021] The present invention introduces functional light-regulating particles of non-uniform particle size into agricultural film based on the multi-frequency resonance effect of non-uniform particles, and utilizes the phenomenon that a portion of light deviates from the original propagation direction when light passes through non-uniform media, and the different forward scattering capabilities of particles of different particle sizes for different wavelengths of sunlight to achieve the change of the propagation path of sunlight by the film, thereby effectively increasing the scattered light in the greenhouse, making the plants more evenly illuminated, and effectively increasing the photosynthetic area of ​​the plants. At the same time, the absorption of near-infrared wavelengths of sunlight by functional light-regulating particles can effectively reduce the temperature in the greenhouse.

[0022] The forward scattered light heat insulation film based on the multi-frequency resonance effect provided by the present invention has a visible light transmittance of more than 80%, and can effectively absorb ultraviolet light in the 280-380nm band that is harmful to plant growth and infrared light in the 800-2500nm band that is useless to plant growth but can cause greenhouse heat stress. The forward scattered light heat insulation film of the present invention reduces the transmission of heat by regulating sunlight, thereby playing a role in heat insulation, can effectively reduce the energy consumption of greenhouse temperature control facilities, and is a high-performance material with heat insulation function.

[0023] The present invention coats the surface of the forward scattered light heat insulation film with a hydrophobic material to make the surface of the film hydrophobic. The fluid forms a large contact angle on the surface of the forward scattered light heat insulation film and slides down in the shape of water droplets. While sliding down, the dust accumulated on the surface of the film is cleared, so that the film has a self-cleaning effect, avoiding the reduction of the light conversion effect of the film due to dust accumulation.

[0024] The single-layer film structure of the forward scattered light heat-insulating film based on the multi-frequency resonance effect of the present invention has the advantages of low cost, simple process, and easy large-scale production. The raw materials required by the present invention can be purchased through commercial channels. After the original industrial transparent coating manufacturing equipment is modified, the film forming equipment can be added to prepare it. The construction efficiency is fast and the film flatness is good. It can be conveniently and quickly constructed and modified for existing greenhouses, greenhouses, plant factories, etc., and has great social and economic benefits, and the market prospects are very broad. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a real photo of the forward scattered light heat insulation film based on the multi-frequency resonance effect prepared in Example 1;

[0026] Figure 2 A comparison diagram of the film space energy distribution of a conventional agricultural film and the forward scattered light heat-insulating film of the present invention obtained based on a film optical model designed by finite element analysis;

[0027] Figure 3 This is a graph showing the variation of the scattering phase function of a particle system with a particle size distribution peak of 50 nm at a red wavelength of 650 nm as a function of the scattering angle, calculated using the multi-sphere T matrix method;

[0028] Figure 4 This is a spectrum characteristic diagram of the forward scattered light heat insulation film based on the multi-frequency resonance effect prepared in Example 1;

[0029] Figure 5 This is a comparison chart of the full-angle solar radiation illuminance test of the forward scattered light heat insulation film based on the multi-frequency resonance effect prepared in Example 2 and the traditional agricultural film;

[0030] Figure 6 This is a photo of the contact angle between the forward scattered light heat-insulating film with surface hydrophobicity based on the multi-frequency resonance effect prepared in Example 2 and a water droplet;

[0031] Figure 7 This is a comparison chart of plant growth tests of the forward scattered light heat insulation film based on the multi-frequency resonance effect prepared in Example 1. The plants in the upper row are the forward scattered light heat insulation film group, and the plants in the lower row are the traditional agricultural film group;

[0032] Figure 8 This is a comparison chart of fresh weight of plant growth tests of the forward scattered light thermal insulation film based on the multi-frequency resonance effect prepared in Example 1 and the traditional agricultural film. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below in conjunction with the embodiments, but it is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be included in the protection scope of the present invention. The process equipment or devices not specifically noted in the following embodiments are all conventional equipment or devices in the art. If not specifically specified, the raw materials used in the embodiments of the present invention can be obtained commercially; if not specifically specified, the technical means used in the embodiments of the present invention are all conventional means well known to those skilled in the art.

[0034] Example 1

[0035] The present embodiment provides a forward scattering light insulation film based on the multi-frequency resonance effect; it contains the following components in parts by weight: 2 parts of light regulating particles, 70 parts of acrylic resin with a solid content of 50%, 22 parts of deionized water, 0.3 parts of BYK333 leveling agent, 0.3 parts of BYK192N dispersant, 0.3 parts of Digo 901W silicone defoaming agent, 0.3 parts of Digo 8100 wetting agent, 3 parts of DPNB film-forming aid, 0.2 parts of BYK420 anti-sagging aid and 0.5 parts of RM8W thickener.

[0036] In this embodiment, the light-regulating particles are non-uniform particles with a particle size distribution range of 10 to 100 nm, specifically a combination of ATO particles and GTO particles in an equal mass ratio.

[0037] The method for preparing the forward scattered light heat insulation film based on the multi-frequency resonance effect in this embodiment includes the following steps:

[0038] Step 1: Deionized water, leveling agent, dispersant, defoamer, wetting agent and a combination of light-regulating particles ATO particles and GTO particles are placed in a dispersion tank in sequence, and stirred at a speed of 500 rpm / min for 5 minutes to obtain a mixed system I;

[0039] Step 2: Add acrylic resin and film-forming aid to the obtained mixed system I, and stir at a speed of 800 rpm / min for 10 min to obtain a mixed system II;

[0040] Step 3: adding an anti-sagging agent and a thickener to the obtained mixed system II, and stirring at a speed of 800 rpm / min for 10 min to obtain a mixed system III;

[0041] Step 4: Filter the obtained mixed system III through a 100-mesh double-layer filter and then spray it on a transparent film with a coating thickness of 200 μm. After drying at room temperature at 20° C., a forward scattered light heat-insulating film based on a multi-frequency resonance effect is obtained.

[0042] Example 2

[0043] This embodiment provides a forward-scattering light heat-insulating film based on the multi-frequency resonance effect with a hydrophobic layer coated on the surface. The only difference between this embodiment and embodiment 1 is that the preparation method of this embodiment also includes step five, spraying a layer of transparent polytetrafluoroethylene with a thickness of 20 μm of hydrophobic material on the surface of the forward-scattering light heat-insulating film based on the multi-frequency resonance effect obtained in step four, to obtain a forward-scattering light heat-insulating film based on the multi-frequency resonance effect with a self-cleaning function.

[0044] Example 3

[0045] The present embodiment provides a forward scattering light insulation film based on the multi-frequency resonance effect; it contains the following components in parts by weight: 1 part of light regulating particles, 65 parts of acrylic resin with a solid content of 50%, 27 parts of deionized water, 0.3 parts of BYK333 leveling agent, 0.3 parts of BYK192N dispersant, 0.3 parts of Digo 901W silicone defoaming agent, 0.3 parts of Digo 8100 wetting agent, 3 parts of DPNB film-forming aid, 0.2 parts of BYK420 anti-sagging aid and 0.5 parts of RM8W thickener.

[0046] In this embodiment, the light-regulating particles are non-uniform particles with a particle size distribution range of 10 to 100 nm, specifically a combination of ITO particles and GTO particles in an equal mass ratio.

[0047] The method for preparing the forward scattered light heat insulation film based on the multi-frequency resonance effect in this embodiment includes the following steps:

[0048] Step 1: sequentially place deionized water, leveling agent, dispersant, defoamer, wetting agent and a combination of light-regulating particles ITO particles and GTO particles in a dispersion tank, and stir at a speed of 500 rpm / min for 5 minutes to obtain a mixed system I;

[0049] Step 2: Add acrylic resin and film-forming aid to the obtained mixed system I, and stir at a speed of 800 rpm / min for 10 min to obtain a mixed system II;

[0050] Step 3: adding an anti-sagging agent and a thickener to the obtained mixed system II, and stirring at a speed of 800 rpm / min for 10 min to obtain a mixed system III;

[0051] Step 4: Filter the obtained mixed system III through a 100-mesh double-layer filter and then spray it on a transparent film with a coating thickness of 200 μm. After drying at room temperature at 20° C., a forward scattered light heat-insulating film based on a multi-frequency resonance effect is obtained.

[0052] Example 4

[0053] The present embodiment provides a forward scattering light insulation film based on the multi-frequency resonance effect; it contains the following components in parts by weight: 3 parts of light regulating particles, 60 parts of acrylic resin with a solid content of 50%, 32 parts of deionized water, 0.3 parts of BYK333 leveling agent, 0.3 parts of BYK192N dispersant, 0.3 parts of Digo 901W silicone defoaming agent, 0.3 parts of Digo 8100 wetting agent, 3 parts of DPNB film-forming aid, 0.2 parts of BYK420 anti-sagging aid and 0.5 parts of RM8W thickener.

[0054] In this embodiment, the light-regulating particles are non-uniform particles with a particle size distribution range of 10 to 100 nm, specifically a combination of ATO particles and AZO particles in an equal mass ratio.

[0055] The method for preparing the forward scattered light heat insulation film based on the multi-frequency resonance effect in this embodiment includes the following steps:

[0056] Step 1: Deionized water, leveling agent, dispersant, defoamer, wetting agent and a combination of light-regulating particles ATO particles and AZO particles are placed in a dispersion tank in sequence, and stirred at a speed of 500 rpm / min for 5 minutes to obtain a mixed system I;

[0057] Step 2: Add acrylic resin and film-forming aid to the obtained mixed system I, and stir at a speed of 800 rpm / min for 10 min to obtain a mixed system II;

[0058] Step 3: adding an anti-sagging agent and a thickener to the obtained mixed system II, and stirring at a speed of 800 rpm / min for 10 min to obtain a mixed system III;

[0059] Step 4: Filter the obtained mixed system III through a 100-mesh double-layer filter and then spray it on a transparent film with a coating thickness of 200 μm. After drying at room temperature at 20° C., a forward scattered light heat-insulating film based on a multi-frequency resonance effect is obtained.

[0060] Example 5

[0061] The present embodiment provides a forward scattering light insulation film based on the multi-frequency resonance effect; it contains the following components in parts by weight: 1.5 parts of light regulating particles, 70 parts of acrylic resin with a solid content of 50%, 22 parts of deionized water, 0.3 parts of BYK333 leveling agent, 0.3 parts of BYK192N dispersant, 0.3 parts of Digo 901W silicone defoaming agent, 0.3 parts of Digo 8100 wetting agent, 3 parts of DPNB film-forming aid, 0.2 parts of BYK420 anti-sagging aid and 0.5 parts of RM8W thickener.

[0062] In this embodiment, the light-regulating particles are non-uniform particles with a particle size distribution range of 10 to 100 nm, specifically a combination of ITO particles and AZO particles in an equal mass ratio.

[0063] The method for preparing the forward scattered light heat insulation film based on the multi-frequency resonance effect in this embodiment includes the following steps:

[0064] Step 1: Deionized water, leveling agent, dispersant, defoamer, wetting agent and a combination of light-regulating particles ITO particles and AZO particles are placed in a dispersion tank in sequence, and stirred at a speed of 500 rpm / min for 5 minutes to obtain a mixed system I;

[0065] Step 2: Add acrylic resin and film-forming aid to the obtained mixed system I, and stir at a speed of 800 rpm / min for 10 min to obtain a mixed system II;

[0066] Step 3: adding an anti-sagging agent and a thickener to the obtained mixed system II, and stirring at a speed of 800 rpm / min for 10 min to obtain a mixed system III;

[0067] Step 4: Filter the obtained mixed system III through a 100-mesh double-layer filter and then spray it on a transparent film with a coating thickness of 200 μm. After drying at room temperature at 20° C., a forward scattered light heat-insulating film based on a multi-frequency resonance effect is obtained.

[0068] Effect verification test:

[0069] 1. Light scattering simulation test

[0070] Figure 2 This is a comparison of the spatial energy distribution of the conventional agricultural film and the forward scattered light heat insulation film of the present invention obtained based on the film optical model designed by finite element analysis; through the comparison, it can be seen that the introduction of light-regulating particles disrupts the direct light transmittance of the conventional film, thereby effectively increasing the spatial energy scattering. This shows that the film has a good light scattering effect, can effectively increase the scattered light in the greenhouse, and make the plants receive light more evenly.

[0071] Due to the multi-frequency resonance effect of particles, particles of different sizes have different wavelength-dependent responses to light of different wavelengths. In order to obtain better forward scattering performance of the film, the multi-sphere T matrix method was used to calculate the scattering characteristics of particles with a peak size distribution of 50nm at a red wavelength of 650nm. Figure 3 As shown, it can be seen that the particle system has a good forward scattering effect at the photosynthetic active wavelength.

[0072] 2. Thin film spectral characteristics test

[0073] Figure 4The spectral characteristics of the forward-scattering light insulation film prepared in Example 1 are shown. It can be seen from the figure that the forward-scattering light insulation film has a high visible light transmittance, and the average transmittance in the 380-780nm band is as high as 85.9%, which is higher than the average visible light transmittance of about 80% of traditional agricultural films. In addition, the film effectively shields long-wave near-infrared that may cause greenhouse heat stress or increase energy consumption of greenhouse refrigeration facilities. It can be seen that this phenomenon is mainly caused by the absorption of the film.

[0074] 3. Film forward light scattering performance test

[0075] Figure 5 The relative irradiance when the front surface of the leaf is at different angles (0-360°) to the light source is shown, where the irradiance of the leaf facing the light source is set to 100%. The results show that compared with traditional films, the forward scattered light heat insulation film provided by the present invention effectively enhances the relative irradiance in the ranges of 0-90° and 270-360° (maximum enhancement of 36%). This shows that the film can effectively transmit nearly parallel sunlight to photosynthetic organisms from all directions, allowing diffuse radiation to enter the plant canopy. This improves the light distribution, effectively reduces or eliminates the phenomenon of uneven light and large shadows of photosynthetic organisms, thereby increasing the photosynthetic area of ​​the plant and effectively promoting plant growth.

[0076] 4. Hydrophobic effect test

[0077] The water contact angle of the forward scattered light heat insulation film based on the multi-frequency resonance effect prepared in Example 2 was measured. The results are as follows: Figure 6 As shown. The average contact angle of the scattered light heat-insulating film prepared in Example 2 is 143.5°, which is in the hydrophobic range. This contact angle will cause the liquid on the surface of the film to be unable to completely adhere, but to form small water droplets on the surface. Under the action of wind or gravity, the small water droplets aggregate and become larger, and further flow or slide away to take away the dust on the surface of the film, thereby achieving a self-cleaning effect and avoiding the problem of reduced light conversion ability of the film caused by dust accumulation.

[0078] 5. Test on promoting plant growth effect

[0079] The present invention conducted a plant cultivation experiment in an outdoor scaled greenhouse model to quantify the effect of the forward scattered light heat insulation film based on the multi-frequency resonance effect on plant growth. The forward scattered light heat insulation film prepared in Example 1 and the traditional agricultural film were used for comparative experiments. The test results are as follows: Figure 7 , Figure 8 shown. Figure 7It can be seen that the leaves of the plants under the diffuse light insulation film gradually spread out to a greater extent, while the leaves of the control group crops gathered in the middle. This difference can be attributed to the fact that the traditional film only provides direct light, which leads to uneven lighting of the crops, with the upper part of the crops receiving more light than the lower part. The diffuse light insulation film can distribute a larger amount of diffuse light to the crops, thereby achieving more uniform lighting. This causes the leaves of the experimental group crops to gradually stretch outward, which effectively increases the photosynthesis area of ​​the crops. Figure 8 The results show that the weight gain of crops under the diffuse light insulation film is 1.63 times higher than that under the conventional film environment. Compared with the conventional film, the growth of crops under the diffuse light insulation film is significantly enhanced.

Claims

1. A forward scattered light heat insulation film based on multi-frequency resonance effect, characterized in that: The invention contains the following components in parts by weight: 0.1 to 3 parts of light-regulating particles, 50 to 75 parts of a base material, 20 to 40 parts of a solvent, 0.1 to 1 part of a leveling agent, 0.1 to 1 part of a dispersant, 0.1 to 1 part of a defoaming agent, 0.1 to 1 part of a wetting agent, 1 to 5 parts of a film-forming aid, 0.1 to 1 part of an anti-sagging agent and 0.1 to 1 part of a thickener; the light-regulating particles are non-uniform particles with a particle size distribution range of 10 to 100 nm.

2. According to claim 1, a forward scattered light heat insulation film based on multi-frequency resonance effect is characterized in that: The light-regulating particles include one or a combination of ATO particles, GTO particles, ITO particles or AZO particles.

3. The forward scattered light heat insulation film based on multi-frequency resonance effect according to claim 1 or 2, characterized in that: The light-regulating particles are a combination of ATO particles and GTO particles, or a combination of ITO particles and GTO particles, or a combination of ATO particles and AZO particles, or a combination of ITO particles and AZO particles.

4. The forward scattered light heat insulation film based on multi-frequency resonance effect according to claim 3, characterized in that: The base material is acrylic resin; the solvent is deionized water; the leveling agent is one or a combination of carboxymethyl cellulose or silicone leveling agents; the dispersant is one or a combination of sodium tripolyphosphate, sodium hexametaphosphate, sodium silicate or modified polyether dispersants; the defoamer is one or a combination of silicone defoamers; the wetting agent is one or a combination of butyl naphthalene sulfonate sodium salt, sodium dodecyl sulfate, a condensate of fatty alcohol and ethylene oxide or an alcohol ether wetting agent; the film-forming aid is one or a combination of alcohol esters, alcohols, alcohol ether esters or alcohol ether film-forming aids; the anti-sagging aid is BYK420 anti-sagging aid; the thickener is one or a combination of cellulose ether, polyurethane thickener or polyacrylate.

5. The forward scattered light heat insulation film based on multi-frequency resonance effect according to claim 4, characterized in that: The surface of the forward scattered light heat-insulating film is also coated with a hydrophobic layer.

6. The forward scattered light heat insulation film based on multi-frequency resonance effect according to claim 5, characterized in that: The hydrophobic layer on the surface of the forward scattered light heat insulation film is a hydrophobic material polytetrafluoroethylene which is coated on the surface of the forward scattered light heat insulation film by spraying, scraping, flow coating or brushing.

7. A method for preparing a forward scattered light heat-insulating film based on a multi-frequency resonance effect as claimed in any one of claims 1 to 4, characterized in that: The steps include: Step 1: sequentially mixing and stirring the solvent, the leveling agent, the dispersant, the defoaming agent, the wetting agent and the light-regulating particles to obtain a mixed system I; Step 2: adding a base material and a film-forming aid to the obtained mixed system I, mixing and stirring to obtain a mixed system II; Step 3, adding an anti-sagging agent and a thickener to the obtained mixed system II, mixing and stirring to obtain a mixed system III; Step 4: Filter the obtained mixed system III and spray it on a transparent film, and then dry it at room temperature to obtain a forward scattered light heat insulation film based on the multi-frequency resonance effect.

8. The method for preparing a forward scattered light heat-insulating film based on a multi-frequency resonance effect according to claim 7, characterized in that: The mixing and stirring speed in step 1 is 400-600 rpm / min; the mixing and stirring speeds in steps 2 and 3 are both 600-1000 rpm / min.

9. The method for preparing a forward scattered light heat-insulating film based on multi-frequency resonance effect according to claim 7 or 8, characterized in that: In step 4, the mixed system III is filtered using a 100-mesh double-layer filter, and the spraying thickness is 150 to 300 μm.

10. Application of the forward scattered light heat-insulating film based on multi-frequency resonance effect as claimed in claims 1 to 6 in the field of agricultural films.

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