阅读说明：本技术 一种涂料及其制备方法和应用 (Coating and preparation method and application thereof ) 是由 林建伟 张付特 孙海龙 薛虎 唐邓 李君君 于 2021-08-23 设计创作，主要内容包括：本发明涉及一种涂料及其制备方法和应用,其制备方法为：将铟盐和锡盐在pH为9-10的反应液中静置陈化,得沉淀,烘干研磨,加油酸得氢氧化铟锡的油酸溶液；加油氨和十八烯,除水,在保护气下升温至300-320℃,搅拌下注入氢氧化铟锡的油酸溶液,300-320℃保温反应,降至室温,加沉淀剂制得纳米氧化铟锡；加纳米氧化铟锡、表面活性剂、氟碳树脂和有机溶剂分散得纳米氧化铟锡分散液；将纳米氧化铟锡分散液、氟碳树脂、丙烯酸树脂、聚氨酯树脂、有机溶剂、固化剂和催化剂配制成涂料。该方法工艺简单,能制出大量红外阻隔好的纳米氧化铟锡,因此用该涂料制备的光伏背板具有好的红外阻隔和降温效果、可见光透过率好、耐老化、耐黄变。(The invention relates to a coating and a preparation method and application thereof, wherein the preparation method comprises the following steps: standing and aging indium salt and tin salt in a reaction solution with the pH of 9-10 to obtain a precipitate, drying and grinding the precipitate, and adding oleic acid to obtain an oleic acid solution of indium tin hydroxide; adding ammonia and octadecene, removing water, heating to 320 ℃ under protective gas, stirring, adding an oleic acid solution of indium tin hydroxide, carrying out heat preservation reaction at 320 ℃ under 300 ℃, cooling to room temperature, and adding a precipitator to prepare nano indium tin oxide; adding nano indium tin oxide, a surfactant, fluorocarbon resin and an organic solvent to disperse to obtain nano indium tin oxide dispersion liquid; the coating is prepared from nano indium tin oxide dispersion liquid, fluorocarbon resin, acrylic resin, polyurethane resin, an organic solvent, a curing agent and a catalyst. The method has simple process, and can prepare a large amount of nano indium tin oxide with good infrared barrier, so the photovoltaic back plate prepared by the coating has good infrared barrier and cooling effects, good visible light transmittance, aging resistance and yellowing resistance.)

1. A preparation method of the coating is characterized by comprising the following steps:

step one, indium salt and tin salt are used as precursors, standing and aging are carried out in a reaction solution with the pH value of 9-10 to separate out a precipitate, the precipitate is washed to be neutral, drying and grinding are carried out, and then oleic acid is added to obtain an oleic acid solution of indium tin hydroxide;

step two, adding a proper amount of oil ammonia and octadecene into a reactor, vacuumizing to remove water, heating to 300-;

adding a surfactant, fluorocarbon resin and an organic solvent into the nano indium tin oxide, and uniformly dispersing to obtain nano indium tin oxide dispersion liquid;

and step four, taking a certain amount of the nano indium tin oxide dispersion liquid, adding fluorocarbon resin, acrylic resin, polyurethane resin, an organic solvent, a curing agent and a catalyst, and preparing the coating.

2. The method for preparing the coating according to claim 1, wherein the particle size of the nano indium tin oxide is 40-50 nm.

3. The method of claim 1, wherein In the first step, the ratio of Sn to In the indium salt and tin salt is 5-12%.

4. The method for preparing the coating according to claim 1, wherein in the second step, the shielding gas is a rare gas; the temperature of the incubation reaction was 320 ℃.

5. The preparation method of the coating according to any one of claims 1 to 4, wherein in the fourth step, the mass ratio of the nano indium tin oxide dispersion liquid to the added fluorocarbon resin, acrylic resin, polyurethane resin, organic solvent, curing agent and catalyst is 0.5-5:100:26:17:11:58:37:16:22: 1.

6. The preparation method of the coating according to claim 5, wherein in the fourth step, the mass ratio of the nano indium tin oxide dispersion to the added fluorocarbon resin, acrylic resin, polyurethane resin, organic solvent, curing agent and catalyst is 1:100:26:17:11:58:37:16:22: 1.

7. The method for preparing the coating according to claim 1, wherein in the step one, the specific steps of precipitating out the precipitate are as follows: adding a certain amount of indium salt and tin salt into a hydrochloric acid solution for dissolving to obtain an indium tin precursor, then dropwise adding the indium tin precursor and ammonia water into a container together in a bidirectional dropwise adding mode to obtain a reaction solution with the pH of 9-10, uniformly stirring the reaction solution, standing and aging to separate out a precipitate.

8. The method for preparing a coating according to claim 1, wherein in the second step, the precipitant is a mixture of ethanol and n-heptane;

the method for preparing the nano indium tin oxide by adding the precipitator comprises the following specific steps: and adding a mixed solution of ethanol and n-heptane into the indium tin oxide sol to obtain an indium tin oxide precipitate, and repeatedly cleaning for multiple times to obtain the nano indium tin oxide.

9. The method of claim 1, wherein in steps three and four, the fluorocarbon resin is at least one of polytetrafluoroethylene, polyvinylidene fluoride, and tetrafluoroethylene/hexafluoropropylene copolymer.

10. A coating material, characterized in that it is produced by a method for producing a coating material according to any one of claims 1 to 9.

11. The application of the coating, which is characterized in that the photovoltaic back plate is obtained by applying the coating of claim 10 on the surface of a substrate and heating and curing the coating.

Technical Field

The invention belongs to the technical field of infrared barrier materials, and particularly relates to a coating as well as a preparation method and application thereof.

Background

As traditional fossil energy sources are gradually depleted, solar energy is considered to be one of the most promising clean energy sources to replace traditional fossil energy sources. The solar cell can convert the direct radiation energy of the sun, can utilize the diffusion energy of the sunlight with the same conversion efficiency, can be used in any place with the sunlight, is not limited by regions, and has attracted extensive attention and rapidly developed in the aspects of commercialization and academic research in recent years. The electromagnetic radiation energy of sunlight passes through many intermediate surfaces, either transmitted or reflected at interfaces, before entering the power generation system to become available energy. For a solar cell module, when light enters the solar cell module from air, the first surface is photovoltaic packaging glass, a packaging polymer film or a condensing lens in a condensing solar cell, and the antireflection film prepared on the middle surfaces can effectively reduce interface reflection, so that more light is transmitted into a solar power generation system, and the antireflection film plays an important role in improving the power generation efficiency of the solar power generation system.

Currently, silicon-based solar cells are widely used in the photovoltaic industry, but under the continuous irradiation of sunlight, the surface temperature of the silicon-based solar cells is sharply increased, and the conversion efficiency of the cells is reduced by at least 0.45% when the working temperature is increased by 1 ℃. Therefore, lowering the surface temperature of the solar cell is critical to maintaining high cell conversion efficiency. Most of the existing methods for cooling solar cells are heat dissipation by heat exchange, including heat pipe cooling, active cooling (by spraying water) and liquid immersion cooling, but their cooling effects depend on heat transfer area and wind speed, or water amount and additional power used for pumping water, and the cooling stability is poor, the cooling effect is not good, and a large amount of cooling liquid is needed, and the cooling process is complex. In the existing transparent heat-insulating coating, for example, the application number CN200910051923.9 discloses a transparent heat-insulating ultraviolet-proof coating and a preparation method thereof, the infrared blocking and ultraviolet-proof performance of the coating is improved by adding nano slurry, but the infrared blocking effect of the coating is poor, and the visible light transmittance of the coating is poor, so that the coating is difficult to be applied to a solar power generation system.

Disclosure of Invention

One of the purposes of the invention is to overcome the defects of the prior art and provide a preparation method of a coating, the preparation method has simple process, can prepare a large amount of nano indium tin oxide with an infrared blocking function, the nano indium tin oxide can be dispersed in a transparent coating to realize good infrared blocking through simple modification, and the obtained coating has high visible light transmittance, good aging resistance and yellowing resistance except infrared blocking.

The second purpose of the invention is to overcome the defects of the prior art, provide a coating with high infrared barrier, good visible light transmittance, aging resistance and yellowing resistance, and the coating has good adhesion with the packaging adhesive film EVA and POE, and can be suitable for preparing a photovoltaic back plate.

The invention also aims to overcome the defects of the prior art and provide an application method of the coating to prepare the coating type photovoltaic back plate, so that the photovoltaic back plate has good visible light transmittance and excellent infrared barrier property to improve the heat dissipation and cooling effects of the photovoltaic back plate, is aging-resistant, yellowing-resistant and good in bonding property with an encapsulation adhesive film, and can improve the reliability, stability and power generation capacity of the photovoltaic module in long-term outdoor use.

Based on the above, the invention discloses a preparation method of a coating, which comprises the following steps:

step one, indium salt and tin salt are used as precursors, standing and aging are carried out in a reaction solution with the pH value of 9-10 to separate out a precipitate, the precipitate is washed to be neutral, drying and grinding are carried out, and then oleic acid is added to obtain an oleic acid solution of indium tin hydroxide;

step two, adding a proper amount of oil ammonia and octadecene into a reactor, vacuumizing to remove water, heating to 300-;

adding a surfactant, fluorocarbon resin and an organic solvent into the nano indium tin oxide, and uniformly dispersing to obtain nano indium tin oxide dispersion liquid;

and step four, taking a certain amount of the nano indium tin oxide dispersion liquid, adding fluorocarbon resin, acrylic resin, polyurethane resin, an organic solvent, a curing agent and a catalyst, and preparing the coating.

Preferably, the particle size of the nano indium tin oxide is 30-80nm, preferably 40-50nm, and the particle size of the nano indium tin oxide is adjusted by the ratio of the indium salt to the tin salt, the temperature of the heat preservation reaction and other heat preservation reaction conditions (such as oleic acid solution of indium tin hydroxide injected rapidly under stirring).

Preferably, in the step one, the specific steps of precipitating the precipitate are as follows: adding a certain amount of indium salt and tin salt into a hydrochloric acid solution for dissolving to obtain an indium tin precursor, then dropwise adding the indium tin precursor and ammonia water into a container together in a bidirectional dropwise adding mode to obtain a reaction solution with the pH of 9-10, uniformly stirring the reaction solution, standing and aging to separate out a precipitate.

Preferably, in the first step, the stirring time is 0.5-2h, preferably 1h, and the standing and aging time is 2-4h, preferably 3 h; after said grinding, in (OH) is obtained₃And Sn (OH)₄And (3) adding the mixed solid powder into oleic acid for dissolving to obtain the oleic acid solution of the indium tin hydroxide.

Preferably, in the first step, the indium salt is indium chloride trihydrate, indium sulfate or indium acetate; the tin salt is stannic chloride pentahydrate, stannic sulfate or stannic acetate; the ratio of Sn to In is 5-12 percent; the concentration of the hydrochloric acid solution is 5-15%, preferably 8%.

In the second step, the temperature for vacuumizing and dewatering is 50-70 ℃, preferably 60 ℃, so as to remove the moisture in the ammonia oil and the octadecene, and synthesize the nano indium tin oxide with more uniform particle size; the protective gas is rare gas (such as argon), and the temperature is raised under the protective gas to prevent water vapor from entering the reactor to interfere the reaction, so that the generation of byproducts (such as InOOH) is effectively avoided;

the temperature of the temperature rise is controlled to be 320 ℃ at 300-₃Has the reaction equation of in (OH)₃＝＝InOOH＝＝In₂O₃. If the reaction temperature is maintained below 260 ℃, in (OH)₃Only InOOH can be obtained basically, and then nano indium tin oxide with high crystal lattice is difficult to obtain; if the temperature of the heat preservation reaction is 260 ℃ to 300 ℃, in (OH)₃Obtained are InOOH and In₂O₃The mixture of (a) and (b) further affects the formation of nano indium tin oxide; if the reaction temperature exceeds 320 ℃, the solvent in the reaction system is violently boiled and easy to initiate agglomeration, so that the changed grain diameter of the nano-crystal is not uniform any more, the storage stability of the nano-crystal is reduced, and the normal storage and use of the nano-crystal are influenced. Wherein the optimal temperature of the heat preservation reaction is 320 ℃, the time of the heat preservation reaction is 30-60min, preferably 30min, and the rare gas protection and the solution boiling state are kept in the heat preservation reaction process.

Preferably, in the second step, the precipitant is a mixed solution of ethanol and n-heptane;

the method for preparing the nano indium tin oxide by adding the precipitator comprises the following specific steps: and adding a mixed solution of ethanol and n-heptane into the indium tin oxide sol to obtain an indium tin oxide precipitate, and repeatedly cleaning for multiple times to obtain the nano indium tin oxide.

Preferably, in step three, the surfactant is a siloxane surfactant, such as at least one of KH560, HK570, vinyltriethoxysilane, methyltriethoxysilane and dimethyldiethoxysilane, preferably HK 570;

the fluorocarbon resin is formed by mixing one or more of polychlorotrifluoroethylene, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene/hexafluoropropylene copolymer, ethylene/tetrafluoroethylene copolymer, ethylene/trichlorofluoroethylene copolymer, ethylene/perfluorinated vinyl ether copolymer and ethylene-perfluorinated alkyl vinyl ether copolymer according to any proportion;

the organic solvent is at least one of propylene glycol methyl ether acetate, ethyl acetate and butyl acetate, and propylene glycol methyl ether acetate is preferred.

Preferably, in the third step, the amount of the surfactant is 1-10%, preferably 5%, of the mass of the nano indium tin oxide; the mass ratio of the fluorocarbon resin to the nano indium tin oxide is 1:0.8-1.2, preferably 1:1, and the use amount of the organic solvent is 40-55%, preferably 50% of the mass of the nano indium tin oxide, so as to ensure that the nano indium tin oxide is fully dispersed and improve the compatibility of the nano indium tin oxide dispersion liquid with other components in the coating.

Preferably, in the fourth step, at least one of an inorganic filler, a first aid and a second aid is further added to the nano indium tin oxide dispersion liquid;

further preferably, the first aid is a mixture of an ethylene-acrylic acid copolymer dispersant and an alkyl modified polysiloxane leveling agent, and specifically, the first aid is obtained by mixing the following components in parts by weight: 50-80 parts of ethylene-acrylic acid copolymer dispersant and 20-50 parts of alkyl modified polysiloxane flatting agent, wherein the first auxiliary agent preferably consists of 70 parts of ethylene-acrylic acid copolymer dispersant and 30 parts of alkyl modified polysiloxane flatting agent; the second auxiliary agent is a mixture of a modified acrylic acid leveling agent, a polysiloxane defoaming agent, polyether modified silicone oil, a hindered phenol antioxidant, an ultraviolet absorbent and a light stabilizer, and is specifically obtained by mixing the following components in parts by weight: 60-80 parts of modified acrylic acid leveling agent, 15-25 parts of polysiloxane defoaming agent, 5-15 parts of polyether modified silicone oil, 3-6 parts of hindered phenol antioxidant and 3-6 parts of ultraviolet absorbent, wherein the modified acrylic acid leveling agent preferably comprises 70 parts of modified acrylic acid leveling agent, 20 parts of polysiloxane defoaming agent, 10 parts of polyether modified silicone oil, 5 parts of hindered phenol antioxidant and 5 parts of ultraviolet absorbent;

the hindered phenol antioxidant is at least one of 2, 8-di-tert-butyl-4-methylphenol, tetra [ beta- (3, 5-di-tert-butyl, 4-hydroxyphenyl) propionic acid ] pentaerythritol ester alcohol, beta- (3, 5-di-tert-butyl, 4-hydroxyphenyl) propionic acid octadecyl ester, 1,3, 5-trimethyl-2, 4,6- (3, 5-di-tert-butyl-4-hydroxybenzyl) benzene, beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid isooctyl ester, diethylene glycol bis [ beta- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate ] and triethylene glycol bis [ beta- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate ], preferably isooctyl beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate;

the ultraviolet absorbent is at least one of 2-hydroxy-4-methoxy benzophenone, 2-hydroxy-4-n-octyloxy benzophenone, bis (2,2,6, 6-tetramethylpiperidyl) sebacate, 2- (2-hydroxy-3, 5-ditert-pentylphenyl) benzotriazole, polysuccinic acid (4-hydroxy-2, 2,6, 6-tetramethyl-1-piperidineethanol) ester, 2'- (2' -hydroxy-3 '-tert-butyl-5' -methylphenyl) -5-chlorobenzotriazole and 2, 4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol, preferably 2-hydroxy-4-n-octyloxy benzophenone and bis (2,2,6, 6-tetramethylpiperidinyl) sebacate.

Further preferably, in the fourth step, the mass ratio of the nano indium tin oxide dispersion liquid, the fluorocarbon resin, the acrylic resin, the polyurethane resin, the first aid, the inorganic filler, the organic solvent, the second aid, the curing agent and the catalyst is 0.5-5:100:26:17:11:58:37:16:22:1, and preferably 1:100:26:17:11:58:37:16:22: 1.

Preferably, in the fourth step, the fluorocarbon resin is one or more selected from polychlorotrifluoroethylene, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene/hexafluoropropylene copolymer, ethylene/tetrafluoroethylene copolymer, ethylene/trichlorofluoroethylene copolymer, ethylene/perfluorinated ethylene copolymer, and ethylene-perfluoroalkyl vinyl ether copolymer, which are mixed according to any proportion; the acrylic resin is a copolymer of a network structure formed by crosslinking at least two monomers of methyl acrylate, ethyl acrylate, n-butyl acrylate, methyl methacrylate and n-butyl methacrylate; the polyurethane resin is obtained by reacting liquid isocyanate with liquid polyether or glycol polyester; the curing agent is isocyanate trimer, such as at least one of toluene diisocyanate trimer, hexamethylene diisocyanate trimer, diphenylmethane diisocyanate trimer and isophorone diisocyanate trimer, preferably toluene diisocyanate trimer; the catalyst is an organic tin catalyst, such as at least one of dibutyltin bis (dodecyl sulfur), dibutyltin diacetate and dibutyltin dilaurate, preferably dibutyltin bis (dodecyl sulfur); the inorganic filler is a mixture of nano silicon dioxide and matting powder, and preferably the nano silicon dioxide and the matting powder are mixed according to the mass ratio of 1: 1.

The invention also discloses a coating which is prepared by adopting the preparation method of the coating.

The invention also discloses an application of the coating, wherein the coating is coated on the surface of a substrate and heated and cured to obtain the photovoltaic back plate, and the photovoltaic back plate plays a role in bonding and protecting the photovoltaic module.

Preferably, the coating method is extrusion coating, anilox coating, roller coating, blade coating, spraying or screen printing, and is preferably applied to the front and back of the substrate;

the curing temperature is 80-180 ℃, the curing time is 1-5 min, and preferably the curing time is 5min at 140 ℃; the thickness of the coating after the coating is cured is 5-25 μm.

Preferably, the substrate is selected from a polytrimethylene terephthalate film, a polycarbonate film, a polyethylene naphthalate film, a polybutylene terephthalate film, a polyethylene terephthalate film, or a polymethyl methacrylate film;

preferably, the substrate thickness is 100-.

Compared with the prior art, the invention at least comprises the following beneficial effects:

the preparation process of the coating is simple, a large amount of high-lattice nano indium tin oxide can be obtained by stirring and quickly injecting oleic acid solution of indium tin hydroxide at the temperature of 300-320 ℃, and other byproducts (such as InOOH) are not generated in the nano indium tin oxide basically, so that the nano indium tin oxide can be dispersed in the coating containing fluorocarbon resin, acrylic resin, polyurethane resin, organic solvent, curing agent and catalyst by simple modification of a surfactant, the fluorocarbon resin and an organic solvent to form the transparent coating, the coating not only has high visible light transmittance, but also has good infrared barrier property, after the coating is applied to a photovoltaic backboard, the photovoltaic backboard has high visible light transmittance, and the surface temperature of the photovoltaic backboard and a photovoltaic module can be effectively reduced through the infrared barrier property of the surface of the photovoltaic backboard, the generating capacity of the photovoltaic module can be improved; moreover, the coating is aging-resistant and yellowing-resistant, has good adhesion with an encapsulating adhesive film EVA and POE, is suitable for being coated on the surface of a substrate to prepare a photovoltaic back plate, and the obtained photovoltaic back plate also has good aging-resistant and yellowing-resistant properties, so that the reliability, stability and power generation capacity of the photovoltaic module in long-term outdoor use can be ensured.

In addition, the coating obtained by the invention can realize the rapid production of the photovoltaic back plate only by coating on the surface of the substrate (preferably the front surface and the back surface of the substrate), the process flow is simple, and the preparation cost is low; the obtained photovoltaic back plate has the advantages of visible light transmittance of more than 88%, maximum infrared light barrier of more than 50%, good bonding performance with a packaging adhesive film, aging resistance and yellowing resistance.

Drawings

Fig. 1 is a schematic structural view of a photovoltaic backsheet of the present invention.

Fig. 2 is an SEM image of nano indium tin oxide synthesized in example 1.

Fig. 3 is a graph of light transmittance data for photovoltaic backsheets prepared using the coatings of examples 1-3 and comparative examples 1-2, respectively.

The reference numbers illustrate: coating 1; a substrate 2.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Example 1

The preparation method of the coating of the embodiment includes the following steps:

step one, adding indium acetate and tin acetate (In: Sn ratio is 100:8) into hydrochloric acid solution, dissolving to obtain indium tin precursor, then dropwise adding ammonia water solution and indium tin precursor into a container together In a bidirectional dropwise adding mode to obtain reaction liquid with pH of 9-10, stirring, standing and aging to separate out precipitate, cleaning the precipitate to neutrality, drying at 80 ℃, and grinding to obtain In (OH)₃And Sn (OH)₄And adding the mixed solid powder into oleic acid for ultrasonic dissolution to obtain an oleic acid solution of indium tin hydroxide.

And step two, adding a mixed solvent of oil ammonia and octadecene into the reactor, vacuumizing to remove moisture in the mixed solvent, slowly heating to 320 ℃ under the protection of argon, rapidly injecting an oleic acid solution of indium tin hydroxide under stirring, carrying out heat preservation reaction to obtain blue indium tin oxide sol, and then adding ethanol and n-heptane to obtain the nano indium tin oxide.

Adding the nano indium tin oxide into a siloxane surfactant, fluorocarbon resin and an organic solvent, and uniformly dispersing by using a stirrer to obtain nano indium tin oxide dispersion liquid;

step four, preparing the nano indium tin oxide dispersion liquid, the tetrafluoroethylene/hexafluoropropylene copolymer, the acrylic resin, the polyurethane resin, the first auxiliary agent, the inorganic filler, the organic solvent, the second auxiliary agent, the curing agent and the catalyst according to the mass ratio of 0.5:100:26:17:11:58:37:16:22:1 to obtain the coating of the embodiment.

Wherein, in the third step, the fluorocarbon resin is polytetrafluoroethylene; in the fourth step, the fluorocarbon resin is tetrafluoroethylene/hexafluoropropylene copolymer, the first auxiliary agent is a mixture of an ethylene-acrylic acid copolymer dispersant and an alkyl modified polysiloxane flatting agent, the inorganic filler is a mixture of nano silicon dioxide and matting powder, the second auxiliary agent is a mixture of a modified acrylic acid flatting agent, a polysiloxane antifoaming agent, polyether modified silicone oil, a hindered phenol antioxidant, an ultraviolet absorbent and a light stabilizer, the curing agent is isocyanate trimer, and the catalyst is an organic tin catalyst.

Example 2

The preparation of a coating according to this example is essentially the same as in example 1, with the only difference that:

in the fourth step, the nano indium tin oxide dispersion liquid, fluorocarbon resin, acrylic resin, polyurethane resin, a first aid, an inorganic filler, an organic solvent, a second aid, a curing agent and a catalyst are prepared according to the mass ratio of 1:100:26:17:11:58:37:16:22:1 to obtain the coating of the embodiment.

Example 3

The preparation of a coating according to this example is essentially the same as in example 1, with the only difference that:

in the fourth step, the nano indium tin oxide dispersion liquid, fluorocarbon resin, acrylic resin, polyurethane resin, first aid, inorganic filler, organic solvent, second aid, curing agent and catalyst are prepared according to the mass ratio of 5:100:26:17:11:58:37:16:22:1 to obtain the coating of the embodiment.

Example 4

The preparation of a coating according to this example is essentially the same as in example 1, with the only difference that:

in the first step, indium chloride and tin chloride are used, and the ratio of In to Sn is 100: 12.

Example 5

The preparation of a coating according to this example is essentially the same as in example 1, with the only difference that:

in the first step, indium chloride and tin chloride are used, and the ratio of In to Sn is 100: 5.

Example 6

The preparation of a coating according to this example is essentially the same as in example 1, with the only difference that:

in the second step, the temperature is slowly increased to 310 ℃ under the protection of argon, and then the heat preservation reaction is carried out at 310 ℃.

Example 7

The preparation of a coating according to this example is essentially the same as in example 1, with the only difference that:

in the second step, the temperature is slowly increased to 300 ℃ under the protection of argon, and then the heat preservation reaction is carried out at 300 ℃.

Example 8

The preparation of a coating according to this example is essentially the same as in example 1, with the only difference that:

and all the fluorocarbon resin in the third step and the fourth step is polyvinylidene fluoride.

Comparative example 1

A coating of this comparative example was prepared essentially the same as example 1, except that:

the paint is prepared from indium tin oxide, fluorocarbon resin, acrylic resin, polyurethane resin, a first auxiliary agent, an inorganic filler, an organic solvent, a second auxiliary agent, a curing agent and a catalyst according to a mass ratio of 0:100:26:17:11:58:37:16:22: 1.

Comparative example 2

A coating of this comparative example was prepared essentially the same as example 1, except that:

the paint is prepared from indium tin oxide, fluorocarbon resin, acrylic resin, polyurethane resin, a first auxiliary agent, an inorganic filler, an organic solvent, a second auxiliary agent, a curing agent and a catalyst according to the mass ratio of 10:100:26:17:11:58:37:16:22: 1.

Performance testing

1. SEM test is carried out on the nano indium tin oxide synthesized in example 1, and the test result is shown in figure 2.

As can be seen from FIG. 2, the particle size of the synthesized nano indium tin oxide is in the range of 40-50 nm.

2. The coating materials of examples 1 to 8 and comparative examples 1 to 2 are respectively coated on the front and back surfaces of a substrate (such as PET), and are heated and cured to form corresponding photovoltaic back sheets, wherein the photovoltaic back sheets have a structure shown in fig. 1 and comprise a substrate 2 and a coating layer 1 coated on the front and back surfaces of the substrate 2. The photovoltaic back sheet was tested for light transmittance, and the test results are shown in table 1 and fig. 3.

TABLE 1

As can be seen from the data in table 1 and fig. 3, in comparative example 1, since no infrared blocking agent is added, the infrared transmittance of the photovoltaic back sheet is significantly higher, and thus the infrared blocking performance is poor. In the embodiments 1 to 3, with the increasing of the mass of the nano indium tin oxide dispersion liquid, the infrared blocking performance of the photovoltaic back plate is improved, and the visible light transmittance of the photovoltaic back plate in the embodiments 1 to 3 is more than 88%; however, when the mass of the nano indium tin oxide dispersion liquid is increased to a certain extent, if the mass is increased continuously (see comparative example 2), the visible light transmittance of the photovoltaic back plate is obviously reduced, and the infrared blocking performance of the photovoltaic back plate is not obviously improved, so that the nano indium tin oxide dispersion liquid cannot be added too much.

3. The coatings of examples 1 to 8 and comparative examples 1 to 2 are respectively coated on the front and back of a substrate (such as PET), and are heated and cured to form a photovoltaic back panel, and then the coating 1 cured on the surface of the photovoltaic back panel is attached to a POE encapsulating adhesive film, so that the peel strength of the coating 1 on the surface of the photovoltaic back panel and the POE encapsulating adhesive film and the yellowing performance of the photovoltaic back panel after PCT aging are tested, and the test results are shown in table 2.

TABLE 2

As can be seen from table 2, the initial peel strength of the photovoltaic back sheets and the POE encapsulating adhesive films of examples 1 to 8 and the peel strength after PCT aging are substantially greater than 90N/cm, and it can be seen that the photovoltaic back sheets and the encapsulating adhesive films of examples 1 to 8 have good adhesive properties, and the coatings 1 on the surfaces of the photovoltaic back sheets of examples 1 to 8 have good aging resistance; the photovoltaic back plates of comparative examples 1 and 2 have yellowing difference of more than 2 after PCT60h, and the yellowing significantly affects the visible light transmittance, aging resistance and yellowing resistance of the photovoltaic back plates, and further affects the reliability, stability and power generation capacity of the photovoltaic back plates in long-term outdoor use.

While preferred embodiments of the present invention have been described, additional variations and modifications of these embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the embodiments of the invention.

The technical solutions provided by the present invention are described in detail above, and the principle and the implementation of the present invention are explained in this document by applying specific examples, and the descriptions of the above examples are only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.