Coating composition, uv light converting coating and method for its preparation, photovoltaic cell and photovoltaic module

Abstract

The present invention relates to a coating composition for forming a UV light conversion coating for a photovoltaic cell, a UV light conversion coating prepared therefrom, a method for preparing the UV light conversion coating, and a photovoltaic cell and a photovoltaic module including the coating. The composition includes, by mass: (A) 100 parts of a polyurea precursor resin which is a mixture of a specific aspartate compound and a blocked isocyanate curing agent; (B) 0.5 to 5 parts of a UV light conversion agent; (C) 1 to 5 parts of an adhesion promoter; (D) 10 to 100 parts of an inert diluent. The light conversion coating prepared from the coating composition, when used in a photovoltaic cell or a photovoltaic module, can reduce UV band light transmittance and increase visible light wavelength transmittance, improve light conversion efficiency, and have excellent adhesion and aging resistance.

Description

Technical Field

[0001] This invention relates generally to the field of photovoltaic cells, and more specifically to coating compositions for forming UV light conversion coatings for photovoltaic cells, UV light conversion coatings prepared using the same, methods for preparing the UV light conversion coating, and photovoltaic cells and photovoltaic modules including the coating. Background Technology

[0002] With the depletion of traditional fossil fuels and the deterioration of the human living environment, clean and renewable energy sources such as solar, wind, and hydropower have long been highly valued worldwide. Among them, solar energy, with its inexhaustible and inexhaustible characteristics and advantages, can be said to have become the best choice for solving the energy shortage problem in the 21st century. The core components of photovoltaic power generation are photovoltaic cells and modules, with the goal of continuously improving the power conversion efficiency of cell modules and reducing power generation costs, thereby ultimately achieving "grid parity".

[0003] The solar spectrum ranges from 300nm to 2400nm and can generally be divided into ultraviolet (UV), visible, and infrared light. UV radiation, specifically, refers to the electromagnetic spectrum with frequencies from 750THZ to 30PHz, corresponding to wavelengths from 380nm to 10nm in a vacuum. When sunlight strikes a photovoltaic (PV) module, due to the limitations of the PV material's response to light wavelengths, it can only absorb a portion of specific wavelengths. Shorter UV wavelengths typically cannot be absorbed and converted into electricity, preventing the PV cell from effectively utilizing the entire spectrum. Based on the structural characteristics of existing cells, such as HJT, TOPCon, and BC cells, short-wavelength UV light can damage the passivation layer, thus reducing the cell's efficiency and lifespan.

[0004] Recently, a technology developed to improve the efficiency of photovoltaic devices utilizes wavelength-downshifting films, also known as wavelength conversion films, light conversion films, or light-transfer films. Wavelength-downshifting films absorb shorter wavelength photons and re-emit them at a more favorable longer wavelength. These photons can then be absorbed by the photoconductive layer within the device and converted into electricity. Because wavelength-downshifting films can convert wavelengths in incident light that have poor response (low quantum efficiency) to wavelengths with better response (high quantum efficiency), primarily changing ultraviolet light in sunlight into usable red and blue light, they can maximize the utilization of sunlight without altering the photovoltaic cell's structure, thereby increasing the power generation per unit area.

[0005] Light conversion films are typically prepared by mixing a polymer matrix, a light conversion agent, and various other additives. The light conversion efficiency and other properties of the film are improved mainly by modifying the light conversion agent (see, for example, CN103415589A, CN117431022A) or by designing a formulation that changes the combination of the polymer matrix, the light conversion agent, and various other components (see, for example, CN114716948A, CN114836136A, CN118165664A).

[0006] Since the performance of the light conversion layer significantly affects the performance of photovoltaic cells and photovoltaic modules in which it is applied, there is still a desire in the art to provide a light conversion layer with excellent performance, including light conversion efficiency. Summary of the Invention

[0007] This invention was made in view of the above-mentioned problems existing in the prior art.

[0008] In a first aspect, the present invention provides a coating composition for forming a UV light conversion coating for photovoltaic cells, comprising, by weight:

[0009] (A) 100 parts of polyurea precursor resin, which is a mixture of components AI and A-II:

[0010] AI: Aspartic acid ester compounds or mixtures thereof represented by Formula I that are liquid at room temperature:

[0011]

[0012] Wherein, X is an aliphatic (chain aliphatic and / or alicyclic) group, such as an aliphatic (chain aliphatic and / or alicyclic) C2-C30 alkylene group; R1 and R2 may be the same as or different from each other and are each independently selected from C1-C4 alkyl groups; m is an integer of at least 2, for example 2-4, for example 2-3, preferably 2; and

[0013] A-II: A liquid blocked isocyanate curing agent at room temperature, which is obtained by reacting an aliphatic (chain aliphatic and / or alicyclic) polyol with an aliphatic (chain aliphatic and / or alicyclic) polyisocyanate at a molar ratio r in which the isocyanate group of the polyisocyanate is in excess relative to the hydroxyl group of the polyol, to obtain a reaction product with terminal isocyanate groups, and then blocking the terminal isocyanate groups of the reaction product with a blocking agent;

[0014] The molar ratio of the terminal isocyanate group blocked by the blocking agent in component A-II to the imino-NH- group in component AI is 1.20:1 to 1:1.20.

[0015] (B) 0.5 to 5 parts of UV light conversion agent;

[0016] (C) 1 to 5 parts of adhesion promoter;

[0017] (D) 10 to 100 parts of inert diluent.

[0018] In a second aspect, the present invention provides a UV light conversion coating prepared from a coating composition according to the first aspect of the present invention.

[0019] In a third aspect, the present invention provides a method for preparing a UV light conversion coating according to a second aspect of the present invention, comprising: providing a coating composition according to a first aspect of the present invention; and applying the coating composition onto a substrate surface and curing it by heating to above the unsealing temperature of component A-II.

[0020] In a fourth aspect, the present invention provides a photovoltaic cell comprising a UV light conversion coating formed on the surface of the photovoltaic cell according to a second aspect of the present invention.

[0021] In a fifth aspect, the present invention provides a photovoltaic cell module comprising a UV light conversion coating according to a second aspect of the present invention formed on the inner and / or outer surfaces of the front and / or back glass of the photovoltaic cell module.

[0022] The applicant has discovered that when a UV light conversion coating is prepared using a coating composition comprising the defined polyurea precursor resin (a mixture of aspartic acid ester compound and a blocked isocyanate curing agent), compared to a coating composition comprising other polyurea precursor resins (e.g., wherein other polyamine compounds are used instead of aspartic acid ester compounds) to prepare a UV light conversion coating, the resulting light conversion coating enables photovoltaic cells or photovoltaic modules to more effectively convert UV light into visible light (i.e., reduce the transmittance of UV light and increase the transmittance of visible light wavelengths), thereby improving light conversion efficiency; and simultaneously achieving improved anti-aging properties. Furthermore, in terms of reducing UV light transmittance, increasing visible light transmittance, and improving light conversion efficiency, the UV light conversion coating of the present invention achieves better results than conventional light conversion coatings or films. Detailed Implementation

[0023] To make the inventive objectives, technical solutions, and beneficial technical effects of this application clearer, this application will be described in detail below. It should be noted that the various aspects, features, embodiments, and advantages described in this application can be compatible and / or combined together.

[0024] Unless otherwise specified, the technical terms used in this specification have the same meaning as commonly understood by those skilled in the art.

[0025] Those skilled in the art will understand that, unless otherwise specified, in this application, a number containing n significant digits after the decimal point actually also includes the result of rounding a number containing more significant digits after the decimal point to n significant digits. For example, 0.16 actually covers all numbers in the range from greater than or equal to 0.155 to less than 0.165; 0.166 actually covers all numbers in the range from greater than or equal to 0.1655 to less than 0.1665, and so on.

[0026] In this application, unless otherwise specified, even if the term "about" is not used to modify numerical values, the value should be understood as being modified by "about" to account for measurement errors; the term "about" includes a deviation of ±5% of the stated numerical value, that is, for the numerical value 'a', whether or not it is modified by "about", it should be understood to represent a range of a ± 5%a, i.e., 0.95a to 1.05a. For example, the number "1" should be understood to specifically disclose the numerical value 1, and also disclose a range of 0.95-1.05.

[0027] In this application, unless otherwise specified, the temperature, pressure and atmosphere are referred to as room temperature (also known as ambient temperature, i.e., about 25°C), the pressure as atmospheric pressure, and the atmosphere as atmospheric (air) atmosphere.

[0028] In this application, the term "aliphatic" (also known as "aliphatic") includes chain aliphatic compounds and alicyclic compounds (also known as cyclic aliphatic compounds). Therefore, in this application, when referring to "aliphatic" compounds, it includes chain aliphatic compounds (i.e., chain-like aliphatic compounds), alicyclic compounds (i.e., aliphatic compounds containing aliphatic rings, also known as cyclic aliphatic compounds), or mixtures thereof.

[0029] In this application, the term "blocked isocyanate" refers to an isocyanate compound in which the terminal isocyanate groups are blocked by a blocking agent (capable of reacting with isocyanate groups); the term "blocked isocyanate curing agent" means that it contains at least two terminal isocyanate groups and these terminal isocyanate groups have been blocked by a blocking agent, and that it is capable of deblocking (e.g., by heating) to release the terminal isocyanate groups to react with a compound containing active hydrogen (e.g., hydroxyl, amino).

[0030] In this application, the terms "UV light conversion coating", "light conversion coating", and "light conversion coating" have the same meaning and are used interchangeably.

[0031] In this application, the terms "UV light conversion agent", "light conversion agent" and "light transfer agent" have the same meaning and are used interchangeably.

[0032] In this application, the term "alkylene" refers to a group formed by removing two or more hydrogen atoms from an alkyl group, i.e., a divalent or higher alkylene group.

[0033] In this application, the term "adhesion promoter" refers to a chemical substance that can improve the adhesion between materials and promote the bonding process through physical adsorption or chemical bonding.

[0034] In this application, the term "inert" means that it does not react with other components in the composition during preparation and does not participate in polymerization during curing. Therefore, in this application, the term "inert diluent" means a liquid substance at room temperature used to dilute the composition, thereby reducing its viscosity, that does not react with other components in the coating composition during preparation and does not participate in polymerization during the curing process of the coating composition. Similarly, the term "inert polymer (matrix)" refers to a polymer that is added to the coating composition and does not react with other components in the coating composition during preparation and does not participate in polymerization during the curing process of the coating composition.

[0035] In this application, the term "viscosity" refers to dynamic viscosity, measured in cP (centipoise). The viscosity was measured using a Brookfield viscometer (e.g., using a CP40 rotor) at 5 rpm.

[0036] In this application, when describing the amount or parts of a substance, unless otherwise stated, it refers to mass or parts by mass.

[0037] This invention relates to coating compositions for forming UV light conversion coatings for photovoltaic cells, UV light conversion coatings prepared therefrom, methods for preparing UV light conversion coatings, and photovoltaic cells and photovoltaic modules including said UV light conversion coatings.

[0038] The present invention will be described in detail below.

[0039] Coating composition

[0040] In a first aspect, the present invention relates to a coating composition for forming a UV light conversion coating for photovoltaic cells, comprising, by weight:

[0041] (A) 100 parts of polyurea precursor resin, which is a mixture of components AI and A-II:

[0042] AI: Aspartic acid ester compounds or mixtures thereof represented by Formula I that are liquid at room temperature:

[0043]

[0044] Wherein, X is an aliphatic (chain aliphatic and / or alicyclic) group, such as an aliphatic (chain aliphatic and / or alicyclic) C2-C30 alkylene group; R1 and R2 may be the same as or different from each other and are each independently selected from C1-C4 alkyl groups; m is an integer of at least 2, for example 2-4, for example 2-3, preferably 2; and

[0045] A-II: A liquid blocked isocyanate curing agent at room temperature, which is obtained by reacting an aliphatic (chain aliphatic and / or alicyclic) polyol with an aliphatic (chain aliphatic and / or alicyclic) polyisocyanate at a molar ratio r in which the isocyanate group of the polyisocyanate is in excess relative to the hydroxyl group of the polyol, to obtain a reaction product with terminal isocyanate groups, and then blocking the terminal isocyanate groups of the reaction product with a blocking agent;

[0046] The molar ratio of the terminal isocyanate group blocked by the blocking agent in component A-II to the imino-NH- group in component AI is 1.20:1 to 1:1.20.

[0047] (B) 0.5 to 5 parts of UV light conversion agent;

[0048] (C) 1 to 5 parts of adhesion promoter;

[0049] (D) 10 to 100 parts of inert diluent.

[0050] The applicant has discovered that the coating compositions of the present invention, using the defined polyurea precursor resin (a mixture of aspartic acid ester compound and blocked isocyanate curing agent), are suitable for coating (e.g., spraying) applications, and the prepared UV light conversion coating simultaneously exhibits excellent light conversion performance (including low UV wavelength transmittance and high visible light wavelength transmittance, high light conversion efficiency), excellent anti-aging properties, and excellent adhesion to the substrate. Compared to coating compositions using other polyurea precursor resins (e.g., where other polyamine compounds are used instead of aspartic acid ester compounds) to prepare UV light conversion coatings, the prepared light conversion coating enables photovoltaic cells or photovoltaic modules to more effectively convert UV light into visible light (i.e., reduce UV wavelength transmittance and increase visible light wavelength transmittance), improving light conversion efficiency; and simultaneously achieving improved anti-aging properties. Furthermore, in terms of reducing UV wavelength transmittance, increasing visible light wavelength transmittance, and improving light conversion efficiency, the UV light conversion coating of the present invention achieves better results than conventional light conversion coatings or films.

[0051] In embodiments, component AI is an aspartic acid ester compound or mixture thereof represented by formula I that is liquid at room temperature, wherein in formula I, X is an aliphatic (chain aliphatic and / or alicyclic) group, such as an aliphatic (chain aliphatic and / or alicyclic) C2-C30 (e.g., C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, C21, C22, C23, C24, C25, C26, C27, C28, C29, C30, or a mixture of any two or more thereof, or a range defined by any two thereof) alkylene group, preferably, X is selected from one of the following: alkylene Methyl dicyclohexyl, such as 4,4'-methylene-dicyclohexyl; methylene-di(methylcyclohexyl), such as 4,4'-methylene-di(2-methylcyclohexyl), 4,4'-methylene-di(3-methylcyclohexyl); 1,6-hexadiyl; 2-methyl-1,5-pentadiyl; 3-methyl-1,5-pentadiyl; cyclohexylene, such as 1,2-cyclohexyl, 1,3-cyclohexyl, 1,4-cyclohexyl; 1-methyl-2,4-cyclohexyl; 1,3-cyclopentyl.

[0052] In the embodiments, in Formula I, R1 and R2 are the same or different from each other and are each independently selected from C1-C4 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, and tert-butyl.

[0053] In the implementation, in Formula I, m is an integer of at least 2, for example 2-4 (e.g., 2, 3 or 4), for example 2-3, preferably 2.

[0054] In some embodiments, X is methylene dicyclohexyl, such as 4,4'-methylene-dicyclohexyl, R1 and R2 are n-butyl, and m=2.

[0055] In some embodiments, X is methylene-di(methylcyclohexyl) such as 4,4'-methylene-di(2-methylcyclohexyl) or 4,4'-methylene-di(3-methylcyclohexyl), R1 and R2 are ethyl, and m=2.

[0056] For example, component AI may include, but is not limited to, one or more of N,N'-(methylenedi-4,1-cyclohexanediyl)diaspartic acid tetraethyl ester, N,N'-(methylenedi-4,1-cyclohexanediyl)diaspartic acid tetrabutyl ester, and N,N'-(methylenedi-(2-methyl-4,1-cyclohexanediyl))diaspartic acid tetraethyl ester. Component AI may be a commercially available product, such as F420, F524, F520, F2850, etc.

[0057] Preferably, the viscosity of component AI, measured at 25°C using a Brookfield viscometer (e.g., using a CP40 rotor) at 0.5 rpm, is in the range of 500 ~ 5000 cp, preferably 1000 ~ 1500 cp. cp, such as 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300, 3400, 3500, 3600, 3700, 3800, 3900, 4000, 4100, 4200, 4300, 4400, 4500, 4600, 4700, 4800, 4900, 5000cp, or a range defined by any two of them.

[0058] In this embodiment, component A-II is a blocked isocyanate curing agent that is liquid at room temperature, obtained by reacting an aliphatic (chain aliphatic and / or alicyclic) polyol with an aliphatic (chain aliphatic and / or alicyclic) polyisocyanate at a molar ratio r in which the isocyanate group of the polyisocyanate is in excess relative to the hydroxyl group of the polyol, to obtain a reaction product with terminal isocyanate groups, and then blocking the terminal isocyanate groups of the reaction product with a blocking agent.

[0059] The aliphatic (chain aliphatic and / or alicyclic) polyol is not particularly limited, and may be, for example, a diol, or a mixture of a diol and a small amount of a polyol containing three or more hydroxyl groups. The diol is not particularly limited and may be, for example, selected from one or more of the following:

[0060] (1) Alkylene glycols; which are not particularly limited and may include, for example, one or more selected from C2-C20 (e.g., C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, or the range defined by any two thereof), such as C2-C10 glycols, for example, one or more selected from: ethylene glycol, propylene glycol (e.g., 1,2-propanediol, 1,3-propanediol, or combinations thereof), butanediol (e.g., 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, other chain isomer glycols or combinations thereof), pentanediol (e.g., 1,2-pentanediol, 1,3- Pentylene glycol, 1,4-pentanediol, 1,5-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 2-methyl-1,4-butanediol, other chain isomer diols or combinations thereof, hexanediol (e.g., 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,3-hexanediol, 2,4-hexanediol, 2,5-hexanediol, 3,4-hexanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, other chain isomer diols or combinations thereof), heptanediol (e.g., 1,2-heptanediol, 1,3-heptanediol, 1,4-heptanediol, 1,5-heptanediol, 1,6-heptanediol, 1,7-heptanediol, 2,3- Heptanediol, 2,4-heptanediol, 2,5-heptanediol, 2,6-heptanediol, 3,4-heptanediol, 3,5-heptanediol, 2-methyl-1,6-hexanediol, 3-methyl-1,6-hexanediol, other chain isomer diols or combinations thereof, octanediol (e.g., 1,2-octanediol, 1,3-octanediol, 1,4-octanediol, 1,5-octanediol, 1,6-octanediol, 1,7-octanediol, 1,8-octanediol, 2-methyl-1,7-heptanediol, 3-methyl-1,7-heptanediol, 4-methyl-1,7-heptanediol, other chain isomer diols or combinations thereof), nonanediol (e.g., 1,2-nonanediol, 1,3-nonanediol, 1,4-nonanediol, 1,5-nonanediol, 1... 6-Nonanediol, 1,7-Nonanediol, 1,8-Nonanediol, 1,9-Nonanediol, 2-methyl-1,8-octanediol, 3-methyl-1,8-octanediol, 4-methyl-1,8-octanediol, other chain isomer diols or combinations thereof, decanediol (e.g., 1,2-decanediol, 1,3-decanediol, 1,4-decanediol, 1,5-decanediol, 1,6-decanediol, 1,7-decanediol, 1,8-decanediol, 1,9-decanediol, 1,10-decanediol, 2-methyl-1,9-nonanediol, 3-methyl-1,9-nonanediol, 4-methyl-1,9-nonanediol, 5-methyl-1,9-nonanediol, other chain isomer diols or combinations thereof), cyclohexanediol (e.g., 1,2-Cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, or combinations thereof; cyclohexanediethanol (e.g., 1,2-cyclohexanediethanol, 1,3-cyclohexanediethanol, 1,4-cyclohexanediethanol).

[0061] (2) An adduct of an alkylene glycol with an alkylene alkane having a different number of carbons than the alkylene glycol; there are no particular limitations on this, and it may include or be an adduct of a C2-C20 alkylene glycol (e.g., as described above for alkylene glycol (1)) with an alkylene alkane (e.g., ethylene oxide, propylene oxide, butane oxide, etc. or combinations thereof). There are no particular limitations on the number of alkylene alkane adducts per molecule of alkylene glycol and it may be, for example, 2-40 (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, or a range defined by any two thereof). There is no particular limitation on the number of alkylene glycols with hydroxyl groups and they can be, for example, 1-20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or a range defined by any two thereof).

[0062] (3) Polyalkylene oxide diols (also known as polyether diols) (e.g., diols obtained by ring-opening polymerization of alkylene oxides (e.g., ethylene oxide, propylene oxide, butane oxide, etc. or combinations thereof); there are no particular limitations and they may be, for example, ring-opening polymerization products of ethylene oxide, propylene oxide, butane oxide, etc. or combinations thereof, such as polyethylene glycol (polyethylene oxide), polypropylene glycol (polypropylene oxide), polybutane glycol (polybutane oxide), polyethylene glycol- Propylene glycol (polyethylene oxide-propylene oxide or ethylene oxide-propylene oxide copolymer), polyethylene glycol-butanediol (polyethylene oxide-butane or ethylene oxide-butane copolymer), polypropylene glycol-butanediol (polypropylene oxide-butane or propylene oxide-butane copolymer), and polyethylene glycol-propylene glycol-butanediol (polyethylene oxide-propylene oxide-butane or ethylene oxide-propylene oxide-butane copolymer).

[0063] (4) Polyester diol; which is a condensation (polymerization) product of an aliphatic (chain aliphatic and / or alicyclic) dicarboxylic acid and an aliphatic (chain aliphatic and / or alicyclic) diol. The dicarboxylic acid is not particularly limited and may include, for example, one or more selected from C2-C20 (e.g., C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, or the range defined by any two thereof), such as C4-C10 aliphatic dicarboxylic acids, for example, one or more selected from: oxalic acid, malonic acid (1,3-malonic acid), succinic acid (e.g., 1,4-Butanoic acid, 2-methyl-1,3-malonic acid or mixtures thereof), glutaric acid (e.g., 1,5-glutaric acid, 2-methyl-1,4-butanoic acid, other chain isomer diacids or mixtures thereof), adipic acid (e.g., 1,6-adipic acid, 2-methyl-1,5-glutaric acid, 3-methyl-1,5-glutaric acid, other chain isomer diacids or mixtures thereof), pimelic acid (e.g., 1,7-pimelic acid, 2-methyl-1,6-hexanediol) Acids, 3-methyl-1,6-adipic acid, other chain isomers of diacids or mixtures thereof, octanoic acid (e.g., 1,8-octanoic acid, 2-methyl-1,7-pimelic acid, 3-methyl-1,7-pimelic acid, 4-methyl-1,7-pimelic acid, other chain isomers of diacids or mixtures thereof), azelaic acid (e.g., 1,9-azelaic acid, 2-methyl-1,8-octanoic acid, 3-methyl-1,8-octanoic acid, 4-methyl-1,8-octanoic acid, etc.), The diol may include, for example, one or more of the following: alkylene glycols, other chain-isomer diacids or mixtures thereof; sebacic acid (e.g., 1,10-sebacic acid, 2-methyl-1,9-azelaic acid, 3-methyl-1,9-azelaic acid, 4-methyl-1,9-azelaic acid, 5-methyl-1,9-azelaic acid, other chain-isomer diacids or mixtures thereof); hexahydrophthalic acid (i.e., 1,2-cyclohexanedicarboxylic acid); or hexahydroterephthalic acid (i.e., 1,4-cyclohexanedicarboxylic acid). The diol may include, for example, one or more of the following: (1) alkylene glycols, (2) adducts of alkylene glycols with alkylene alkane having a different carbon number than the alkylene glycol, and (3) polyalkylene oxide glycols, particularly (1) alkylene glycols, such as C2-C20, such as C2-C10 alkylene glycols.

[0064] (5) Polycarbonate diol; which is a product of the reaction of a diol with a carbonate or phosgene or carbon dioxide. The diol is not particularly limited and may include, for example, one or more of the following: (1) alkylene diols, (2) adducts of alkylene diols with alkylene alkane having a different number of carbon atoms than the alkylene diols, (3) polyalkylene oxide diols, particularly (1) alkylene diols, such as C2-C20, such as C2-C10 alkylene diols.

[0065] (6) Polylactone diol; which is a reaction product obtained by ring-opening polymerization of a lactone using a diol (e.g., selected from (1) alkylene glycols, (2) adducts of alkylene glycols and alkylene oxides with different carbon numbers than the alkylene glycols, (3) polyalkylene oxide diols, especially (1) alkylene glycols, such as C2-C20, such as C2-C10 alkylene glycols) as an initiator. The lactone is not particularly limited and may be, for example, one or more of butyrolactone, valproic acid lactone, caprolactone, and decylactone. The polylactone diol may be, for example, polybutyrolactone diol, polyvalproic acid diol, polycaprolactone diol, and polydecylactone diol.

[0066] or

[0067] (7) Any combination thereof.

[0068] The polyol containing three or more hydroxyl groups is not particularly limited and may be, for example, one or more of glycerol, trimethylolpropane (1,1,1-tris(hydroxymethyl)propane), di(trimethylolpropane), pentaerythritol, and dipentaerythritol. When the aliphatic (chain aliphatic and / or alicyclic) polyol is a mixture of a diol and a small amount of a polyol containing three or more hydroxyl groups, the molar ratio of the polyol containing three or more hydroxyl groups in the aliphatic (chain aliphatic and / or alicyclic) polyol (or the molar ratio of the hydroxyl groups of the polyol containing three or more hydroxyl groups to the total hydroxyl groups in the aliphatic (chain aliphatic and / or alicyclic) polyol) may be, for example, 0.1, 0.2, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0%, or a range defined by any two thereof.

[0069] Preferably, the aliphatic (chain aliphatic and / or alicyclic) polyol (e.g., polyether glycol, polyester glycol, polycarbonate glycol, polylactone glycol) has a hydroxyl value of 28 to 112 mg KOH / g, preferably 56 to 112 mg KOH / g, for example, the following hydroxyl values: 28, 32, 56, 70, 112 mg KOH / g, or a range defined by any two thereof.

[0070] The aliphatic (chain aliphatic and / or alicyclic) polyisocyanates are not particularly limited and may include, for example, one or more of the following: alicyclic polyisocyanates such as diisocyanates, such as 4,4'-dicyclohexylmethane diisocyanate (HMDI), 1,4-cyclohexane diisocyanate, cyclohexane dimethylene diisocyanate, trimethyl-1,6-hexamethylene diisocyanate (e.g., 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 2,4,4-trimethyl-1,6-hexamethylene diisocyanate and mixtures thereof), norbornane diisocyanate (e.g., 2,5-di(isocyanate methyl)bicyclo[2.2.1]heptane, 2,6-di(isocyanate methyl)bicyclo[2.2.1]heptane, or mixtures thereof), methylcyclohexyl diisocyanate and isophorone diisocyanate (IPDI); chain aliphatic polyisocyanates such as diisocyanates, such as HDI One or more of (1,6-hexamethylene diisocyanate). When the aliphatic (chain aliphatic and / or alicyclic) polyisocyanate is a mixture of diisocyanate and a small amount of polyisocyanate containing three or more isocyanate groups, the molar ratio of the polyisocyanate containing three or more isocyanate groups in the aliphatic (chain aliphatic and / or alicyclic) polyisocyanate (or the molar ratio of isocyanate groups in the polyisocyanate containing three or more isocyanate groups to all isocyanate groups in the aliphatic (chain aliphatic and / or alicyclic) polyisocyanate) may, for example, be 0.1, 0.2, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0%, or a range defined by any two thereof.

[0071] In this embodiment, an aliphatic (chain aliphatic and / or alicyclic) polyol reacts with an aliphatic (chain aliphatic and / or alicyclic) polyisocyanate at a molar ratio r in which the isocyanate group of the polyisocyanate is in excess relative to the hydroxyl group of the polyol, i.e., r is greater than 1.0, preferably r is 2.0-5.0, more preferably 2.5-3.5, for example 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, or a range defined by any two of them.

[0072] The sealant is not particularly limited and can be appropriately selected according to the intended use of the coating composition. For example, the sealant may include or be any one or more of butanone oxime, phenol, caprolactam, N-methylaniline, acetylacetone, sodium bisulfite, or ethyl mercaptan.

[0073] In some embodiments, the viscosity of component A-II, measured at 25°C using a Brookfield viscometer (e.g., using a CP40 rotor) at 5 rpm, ranges from 500 to 5000 cp, preferably 3000 to 4500 cp. cp, such as 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300, 3400, 3500, 3600, 3700, 3800, 3900, 4000, 4100, 4200, 4300, 4400, 4500, 4600, 4700, 4800, 4900, 5000 cp, or a range defined by any two of them.

[0074] From the viewpoint of improving the storage stability of the coating composition and facilitating the polymerization of components AI and A-II to form a polyurea by unblocking component A-II, component A-II preferably has an unblocking temperature of 70-170°C, more preferably 90-140°C, and more preferably 100-130°C. For example, the unblocking temperature may be 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170°C, or a range defined by any two thereof.

[0075] There are no particular restrictions on the source of components A-II, and they can be, for example, commercially available products such as YL-GB9300 from Guangdong Yele New Material Manufacturing Co., Ltd., and DXB-3375D from Shaoguan Dongsen Synthetic Materials Co., Ltd.

[0076] In embodiments, the molar ratio of the terminal isocyanate groups blocked by the blocking agent in component A-II to the imino-NH- groups in component AI is 1.20:1 to 1:1.20, preferably 1.10:1 to 1.02:1, more preferably 1.06:1 to 1.04:1, for example 1.20:1, 1.19:1, 1.18:1, 1.17:1, 1.16:1, 1.15:1, 1.14:1, 1.13:1, 1.12:1, 1.10:1, 1.09:1, 1.08:1, 1.07:1, 1. 06:1, 1.05:1, 1.04:1, 1.03:1, 1.02:1, 1.00:1, 1:1.01, 1:1.02, 1:1.03, 1:1.04, 1:1.05, 1:1.06, 1:1.07, 1:1.08, 1:1.09, 1:1.10, 1:1.11, 1:1.12, 1:1.13, 1:1.14, 1:1.15, 1:1.16, 1:1.17, 1:1.18, 1:1.19, 1:1.20, or a range defined by any two of them.

[0077] The viscosity of component A varies depending on the ratio of components AI and A-II and their respective viscosities, and its viscosity, when measured at 25°C using a Brookfield viscometer (e.g., using a CP40 rotor) at 5 rpm, can range from, for example, 500~ 5000cp, for example 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300, 3400, 3500, 3600, 3700, 3800, 3900, 4000, 4100, 4200, 4300, 4400, 4500, 4600, 4700, 4800, 4900, 5000 cp, or the range defined by either or both.

[0078] The coating composition of the present invention contains a mixture of the defined aspartic acid ester compound (AI) and a blocked isocyanate curing agent (A-II). When the coating composition is subsequently applied (coated) to a substrate surface and heated above the deblocking temperature of component A-II, component A-II releases terminal isocyanate groups and reacts with the imino group of the aspartic acid ester compound to form a polyurea structure. The resulting light conversion coating, compared to light conversion coatings prepared using coating compositions containing other polyurea precursor resins (e.g., where other polyamine compounds are used instead of the aspartic acid ester compound), enables photovoltaic cells or photovoltaic modules to more effectively convert UV light into visible light (i.e., reduce UV light transmittance and increase visible light transmittance), thus improving light conversion efficiency; additionally, it also simultaneously achieves improved anti-aging properties.

[0079] Those skilled in the art will understand that although component A in this invention is a mixture of component AI and component A-II, it is also within the scope of this invention to replace part or all of the mixture with the condensation product and / or polycondensation product of component AI and unsealed component A-II, although it is not particularly preferred considering that the viscosity of the coating composition is higher in this case, making it difficult to apply, or requiring a higher amount of diluent for dilution before application.

[0080] In an embodiment, the composition includes 0.5-5 parts by mass of a UV light converter relative to 100 parts by mass of component A. In this application, the UV light converter is also referred to as a light converter or light transfer agent. The UV light converter is not particularly limited and can be any UV light converter commonly used in the art. Preferably, the UV light converter is one that does not adversely affect polymerization during the polymerization process of the composition. The UV light converter may, for example, include one or more selected from organic fluorescent materials, rare-earth luminescent materials, and quantum dot luminescent materials. The organic fluorescent material may include at least one of the following: benzotriazole fluorescent materials (e.g., light converter B1 shown below), rhodamine fluorescent materials (e.g., rhodamine B with the structure shown below, or light converter B2 shown below), carbocyclic materials (e.g., fluorescent whitening agents ER, CBS-X, etc.), triazine-aminostilbene materials (e.g., fluorescent whitening agent DMS), organic triazoles, stilbene-triazole materials (e.g., TinopalPBS, Blankophor BHC, etc.), benzoxazole materials (e.g., fluorescent whitening agent OB-1, fluorescent whitening agent 393, etc.), furans, benzofurans, benzimidazoles, benzotriazoles, and benzothiadiazole skeletons.

[0081]

[0082] The applicant has discovered that, in the coating composition of the present invention, when benzotriazole fluorescent materials are used, the prepared light conversion coating achieves slightly better light conversion efficiency compared to the use of other light conversion agents such as rhodamine fluorescent materials.

[0083] In an embodiment, the coating composition includes 0.5-5 parts by weight of component A relative to 100 parts by weight, for example, light conversion agent in the following amounts: 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 parts by weight, or a range defined by any two thereof.

[0084] In an embodiment, the composition includes an adhesion promoter in the form of 1 to 5 parts per 100 parts by weight of component A. The adhesion promoter is not particularly limited and may be any commonly used in the art. For example, the adhesion promoter may be a silane coupling agent, such as a compound or mixture thereof represented by YL-Si(OR)3, wherein Y is a group selected from vinyl, epoxy, amino, mercapto, and methacryloyloxy groups, L is a single bond or a C1-C10, for example, C1-C5 alkylene group, and R is (e.g., C1-C20) alkyl or aryl; examples of silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-glycidyl etheroxypropyltrimethoxysilane. 3-Glycidyl etheroxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane. These silane coupling agents can be used alone or in combination with each other.

[0085] In an embodiment, the composition includes an adhesion promoter in an amount of 1 to 5 parts per 100 parts by weight of component A, for example, in amounts of 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 parts by weight, or any range defined therein. When the coating composition includes an adhesion promoter in the defined range, the adhesion of the prepared light conversion coating to the substrate can be significantly improved compared to the use of an amount of adhesion promoter below the defined range.

[0086] In an embodiment, the coating composition further includes 10 to 100 parts by weight of an inert diluent relative to 100 parts by weight of component A. The diluent is not particularly limited and may include, for example, one or more of the following: ethyl acetate, butyl acetate, dimethyl carbonate, acetone, butanone, cyclohexanone, propylene carbonate, toluene, xylene, etc. When the coating composition includes at least 10 parts by weight of diluent, the solubility of the light conversion agent in the coating composition is improved compared to using a smaller amount of diluent, resulting in the elimination of insoluble UV light conversion agent particles. This leads to a more uniform distribution of the light conversion agent in the prepared light conversion coating, which is beneficial for obtaining better light conversion performance. There is no particular upper limit to the amount of the diluent used. However, considering that increasing the amount of diluent will lead to increased production costs, increased environmental impact, reduced viscosity of the coating composition which may make it unsuitable for coating, and increased treatment (e.g., heat treatment) time required to remove the diluent, it is preferable that the amount of inert diluent is at most 100 parts by weight, more preferably at most 30 parts by weight, relative to 100 parts by weight of component A, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 parts by weight, or a range defined by any two of these.

[0087] The coating composition may be free of inert (i.e., non-reactive, e.g., non-polymeric) polymer matrices commonly used in the art. However, the coating composition may also contain inert polymer matrices commonly used in the art without departing from the spirit and scope of the invention. For example, the coating composition may contain one or more inert polymer matrices selected from: polyethylene terephthalate, polymethyl methacrylate, polyvinyl butyral, ethylene vinyl acetate copolymer, ethylene tetrafluoroethylene copolymer, polyimide, amorphous polycarbonate, polystyrene, polyurethane, polyacrylate, and combinations thereof. The amount of the polymer matrix is ​​not particularly limited and can be a suitable amount that can dissolve in the coating composition of the present invention, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 parts by weight, or a range defined by any two thereof.

[0088] The coating composition may optionally include one or more other additives (or auxiliaries) commonly used in light conversion layers in the art. The additives may include one or more of, for example, light stabilizers, antioxidants, etc. The light stabilizer is any one or a mixture of at least two of light stabilizers such as light-shielding agents, light stabilizers such as quenchers, light stabilizers such as free radical scavengers, and light stabilizers such as hydroperoxide decomposers; the antioxidant is any one or a mixture of at least two of antioxidants such as hindered phenolic antioxidants, aromatic amine antioxidants, phosphite antioxidants, thioether antioxidants, and metal passivating antioxidants.

[0089] The amount of the additive used can be the commonly used addition amount in the art. For example, in the coating composition, the amount of each additive can be 0.1-5 parts by weight.

[0090] UV light conversion coating

[0091] In a second aspect, the present invention relates to a UV light conversion coating prepared from a coating composition according to the first aspect of the present invention.

[0092] The preparation can be carried out by applying the coating composition to the surface of a substrate and curing it by heating it to above the unsealing temperature of component A-II.

[0093] The thickness of the light conversion coating is not particularly limited, and can be any thickness commonly used in the art for light conversion coatings considering factors such as light conversion efficiency and durability. For example, the thickness of the light conversion coating can be 0.5 μm-1 mm, such as 0.5, 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, 1000 μm, or a range defined by any two of these.

[0094] Using the coating composition according to the first aspect of the invention, the required thickness, shape, and size of the UV light conversion coating can be flexibly controlled as needed; and in terms of converting UV light to visible light (i.e., reducing the transmittance of UV light and increasing the transmittance of visible light wavelength) and conversion efficiency, the UV light conversion coating of the present invention can still have comparable or even better performance than commercially available thicker (e.g., 100 μm) light conversion films even at very thin thicknesses, such as less than 100 μm, for example less than 80 μm, or even less than 50 μm.

[0095] Preparation method of UV light conversion coating

[0096] In a third aspect, the present invention relates to a method for preparing a UV light conversion coating according to a second aspect of the present invention, comprising: providing a coating composition according to a first aspect of the present invention; and applying the coating composition onto a substrate surface and curing it by heating to above the unsealing temperature of component A-II.

[0097] The substrate may be, for example, a photovoltaic cell or a photovoltaic module.

[0098] The coating can be performed by any suitable means known in the art. For example, the coating can be performed by spraying, brushing, scraping, casting, roller coating, etc.

[0099] In one embodiment, the heating causes component A-II to deseal and release isocyanate groups that react with the secondary amino groups of component AI, thereby forming a polyurea structure.

[0100] In this embodiment, the heating is performed at a temperature above the desealing temperature of components A-II. The heating temperature may be 0-60°C higher than the desealing temperature, for example, 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60°C, or a range defined by any two of these.

[0101] In an embodiment, the heating may be carried out for a time sufficient to cause the desealing of components A-II, such as complete desealing, and optionally also to effectively remove the diluent, for example, 0.1-2 hours, such as 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.5, 2.0 h, or a range defined by any two thereof.

[0102] Photovoltaic cells

[0103] In a fourth aspect, the present invention relates to a photovoltaic cell comprising a UV light conversion coating formed on the surface of the photovoltaic cell according to a second aspect of the invention.

[0104] The structure of photovoltaic cells is well known in the field and will not be described in detail here.

[0105] A UV light conversion coating can be formed on a photovoltaic cell by directly applying a coating composition according to the first aspect of the invention onto the surface of the photovoltaic cell, followed by curing by heating to above the desealing temperature of component A-II.

[0106] Alternatively, a UV light conversion coating can be formed on a photovoltaic cell by directly applying a coating composition according to the first aspect of the invention onto the surface of another substrate, followed by curing by heating to above the desealing temperature of components A-II; then peeling the resulting film off the carrier and then setting it on the surface of the photovoltaic cell.

[0107] The setup can be achieved by directly laminating the film onto the surface of the photovoltaic cell. Alternatively, the setup can be achieved by treating the surface of the photovoltaic cell (e.g., applying corona treatment, applying an adhesive, etc.) and then laminating the film onto the treated photovoltaic cell surface.

[0108] After being applied to the surface of the photovoltaic cell, no further functional layers may be applied to the exposed surface of the light conversion coating. Alternatively, a protective layer, for example, to further inhibit oxygen and moisture penetration into the light conversion coating, may be applied to the exposed surface of the light conversion coating. The protective layer may comprise a polymer matrix. In some embodiments, the polymer matrix of the protective layer may comprise a material selected from: polyethylene terephthalate, polymethyl methacrylate, polyvinyl butyral, ethylene vinyl acetate copolymer, ethylene tetrafluoroethylene copolymer, polyimide, amorphous polycarbonate, polystyrene, siloxane sol-gel, polyurethane, polyacrylate, and combinations thereof. The thickness of the protective layer is not particularly limited and may range, for example, from about 10 μm to about 2 mm, or, for example, from about 20 μm to about 1 mm.

[0109] By using the UV light conversion coating of the second aspect of the present invention, the resulting photovoltaic cell can more effectively convert UV light into visible light (i.e., reduce the transmittance of UV light and increase the transmittance of visible light wavelengths) compared to using conventional light conversion films or other light conversion films based on polyurea polymer matrices, thereby improving the light conversion efficiency.

[0110] Photovoltaic cell modules

[0111] In a fifth aspect, the present invention relates to a photovoltaic cell module comprising a UV light conversion coating according to a second aspect of the invention formed on the inner and / or outer surfaces of the front and / or back glass of the photovoltaic cell module.

[0112] A photovoltaic (PV) module, also known as a solar panel, is a power generation device composed of multiple solar cells connected in series or parallel and encapsulated. It typically includes components such as cell cells, encapsulation materials, a backsheet, connectors, and cables. The structure and composition of PV modules are well-known in the art and will not be elaborated upon here.

[0113] The above description of the photovoltaic cell in the fourth aspect of the present invention also applies to the photovoltaic cell module.

[0114] Example

[0115] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0116] The raw material information used in the examples is as follows.

[0117] A1: Polyurea precursor resin FDA-70D from Shenzhen Borui, which is a mixture of the following:

[0118] AI: An aspartic acid ester compound represented by formula I, where X = 4,4'-methylene-dicyclohexyl, R1 and R2 are both n-butyl, and m = 2, with a viscosity of 1100 cp measured at 0.5 rpm using a Brookfield viscometer CP40 rotor at 25 °C; and

[0119] A-II: Blocked isocyanate curing agent, which is formed by blocking the terminal isocyanate groups of the reaction product formed by the reaction of isophorone diisocyanate (IPDI) and poly(hexamethylene carbonate) glycol with a hydroxyl value of 56 mg KOH / g in a molar ratio of 3.0:1 with ethyl mercaptan as a blocking agent. Its unblocking temperature is 110℃, and its viscosity measured at 25℃ using a Brookfield CP40 viscometer rotor at 5 rpm is 3500 cp.

[0120] The molar ratio of the isocyanate groups of component A-II (which are blocked by the blocking agent, i.e., theoretically participate in the subsequent reaction) to the imino group of component AI is 1.05:1.

[0121] The viscosity of the mixture was 2500 cp at 25°C using a Brookfield CP40 viscometer rotor at 5 rpm.

[0122] A2: Polyurea precursor resin 5508 from Covestro, which is a mixture of the following:

[0123] AI: An aspartic acid ester compound represented by formula I, where X = 4,4'-methylene-di(2-methylcyclohexyl), R1 and R2 are ethyl groups, and m = 2, with a viscosity of 1200 cp measured at 0.5 rpm using a Brookfield viscometer CP40 rotor at 25 °C; and

[0124] A-II: Blocked isocyanate curing agent, which is formed by blocking the terminal isocyanate groups of the reaction product formed by reacting 4,4'-dicyclohexylmethane diisocyanate (HMDI) and polypropylene glycol with a hydroxyl value of 56 mg KOH / g in a molar ratio of 3.0:1 with phenol as a blocking agent. Its unblocking temperature is 115℃, and its viscosity measured at 25℃ using a Brookfield CP40 viscometer rotor at 5 rpm is 4200 cp.

[0125] The molar ratio of the isocyanate groups of component A-II (which are blocked by the blocking agent, i.e., theoretically participate in the subsequent reaction) to the imino group of component AI is 1.05:1.

[0126] The viscosity of the mixture was 3200 cp at 25°C using a Brookfield CP40 viscometer rotor at 5 rpm.

[0127] A3: GD-1520, an aliphatic polyurea precursor resin from Shenzhen Gaodun, is a mixture as follows:

[0128] AI: 3-Aminomethyl-3,5,5-trimethylcyclohexylamine, with a viscosity of 125 cp measured at 0.5 rpm using a Brookfield viscometer CP40 rotor at 25°C; and

[0129] A-II: Blocked isocyanate curing agent, which is formed by blocking the terminal isocyanate groups of the reaction product formed by reacting 4,4'-dicyclohexylmethane diisocyanate (HMDI) and polypropylene glycol with a hydroxyl value of 56 mg KOH / g in a molar ratio of 3.0:1 with phenol as a blocking agent. Its unblocking temperature is 115℃, and its viscosity measured at 25℃ using a Brookfield CP40 viscometer rotor at 5 rpm is 4200 cp.

[0130] The molar ratio of the isocyanate groups of component A-II (which are blocked by the blocking agent, i.e., theoretically participate in the subsequent reaction) to the imino group of component AI is 1.05:1.

[0131] The viscosity of the mixture was 1800 cp at 25°C using a Brookfield CP40 viscometer rotor at 5 rpm.

[0132] A4: Aromatic polyurea precursor resin C84725 from Zhongshan Chengzhi, which is a mixture as follows:

[0133] AI: 4,6-Diethyl-2-methyl-1,3-phenylethylamine (also known as 2,6-diamino-3,5-diethyltoluene), whose viscosity at 25°C was 120 cp when measured at 0.5 rpm using a Brookfield viscometer CP40 rotor.

[0134] A-II: Blocked isocyanate curing agent, which is formed by blocking the terminal isocyanate groups of the reaction product formed by reacting 4,4'-diphenylmethane diisocyanate (MDI) with polypropylene glycol with a hydroxyl value of 56 mg KOH / g in a molar ratio of 3.0:1 with phenol as a blocking agent. Its unblocking temperature is 125℃, and the viscosity measured at 25℃ using a Brookfield CP40 viscometer rotor at 5 rpm is 4000 cp.

[0135] The molar ratio of the isocyanate groups of component A-II (which are blocked by the blocking agent, i.e., theoretically participate in the subsequent reaction) to the imino group of component AI is 1.05:1.

[0136] The viscosity of the mixture was 1600 cp at 25°C using a Brookfield CP40 viscometer rotor at 5 rpm.

[0137] B1: Light conversion agent, which comes from Ruiers Technology Co., Ltd., is an anti-aging modified benzotriazole fluorescent material with the structure shown above.

[0138] B2: Light conversion agent, purchased from Maclean's Reagents, is a rhodamine B-type fluorescent agent with the structure shown above.

[0139] C: Adhesion promoter, which is A-I87 (3-glycidyl etheroxypropyltrimethoxysilane) purchased from Momentive.

[0140] D: Diluent, ethyl acetate from Maclean's Reagents.

[0141] Test methods

[0142] 1. Light transmittance: Tested according to standard GB / T 29848-2018 using a UV-Vis spectrophotometer (PerkinElmer LAMBDA 950).

[0143] 2. Light conversion efficiency: Absolute quantum efficiency was measured using a Horiba FL-3 spectrometer at room temperature using an integrating sphere. Light conversion efficiency = number of emitted blue light photons / number of absorbed ultraviolet light photons (excitation at 350nm wavelength).

[0144] 3. Solubility of light conversion agent: Using the light conversion agent as the solute and the mixed liquid of the above components A, C, and D mixed in proportion as the solvent, observe the solubility of 5g of light conversion agent B1 or B2 in 100g of the above mixed liquid.

[0145] 4. Adhesion: Adhesion testing shall be conducted according to the methods and conditions specified in ISO 2409; a 100μm thick coating shall be applied to a 5cm*10cm white glass surface, and then 10*10 square grids (each grid side length 1mm) shall be drawn on the coating using a standard-specified tool. If no coating peels off in any of the 100 grids after testing, the result is 5B; if the coating peels off no more than 5% of the 100 grids, the result is 4B; if the coating peels off more than 5% but not more than 15% of the 100 grids, the result is 3B.

[0146] 5. Aging and yellowing test: The UV-cured light conversion coating film with a thickness of about 100μm was placed in a 200℃ oven. After 3 hours, the film was removed and the b* value after aging was measured using a spectrophotometer manufactured by Hangzhou Caipu Technology Co., Ltd., model CS-821N. This value reflects the aging and yellowing resistance of the light conversion coating.

[0147] All the above tests were conducted at 25℃ and 50%RH.

[0148] Examples 1-8 and Comparative Examples 1-7

[0149] According to the composition shown in Table 1, the light conversion agent (B1-B2) and diluent (D) were placed in a stirred tank and stirred until completely dissolved; polyurea precursor resin (A1-A4) and adhesion promoter (C) were added and stirred until homogeneous, thereby preparing the coating compositions of Examples 1-8 and Comparative Examples 1-7 respectively.

[0150] The coating compositions of Examples 1-8 and Comparative Examples 1-7 were respectively applied to clear glass using a doctor blade and then cured by heat treatment at 130°C for 10 minutes, thereby preparing UV light conversion coatings. Unless otherwise stated, the thickness of the UV light conversion coatings prepared in each example and comparative example is approximately 100 μm.

[0151] The methods described in the Test Methods section were used to test each embodiment and comparative example, and the test results are shown in Tables 2 and 3. The comparative film shown in Table 2 is a commercially available light conversion film (brand: Saiwu, model: WT11).

[0152] As can be seen from Tables 2-3, compared with commercially available light conversion films, the UV light conversion coatings of the same thickness prepared in Examples 1-8 of this invention significantly reduced the transmittance in the UV band (280-380nm) and increased the transmittance in the visible light band (380-1100nm), thereby improving the light conversion efficiency. Furthermore, Table 2 also shows that even with a lower thickness, the UV light conversion coating of this invention can achieve lower transmittance in the UV band (280-380nm), higher transmittance in the visible light band (380-1100nm), and higher light conversion efficiency.

[0153] Table 3 also shows that, compared with the coating compositions of Comparative Examples 1-4 which use polyurea precursor resins A3 or A4 that do not contain aspartic acid ester compounds of Formula I, the UV light conversion coatings prepared by the coating compositions of Examples 1-3 which use polyurea precursor resins A1 or A2 containing aspartic acid ester compounds of Formula I have significantly reduced UV transmittance (280-380nm) and significantly reduced visible light transmittance (380-1100nm), significantly improved UV light conversion efficiency, and significantly reduced yellowing. This indicates that using aspartic acid ester compounds of Formula I to prepare polyurea improves the light conversion performance and anti-aging properties of the resulting UV light conversion coating compared with using other amine compounds to prepare polyurea.

[0154] In addition, as can be seen from Table 3,

[0155] Compared to the light conversion coatings of Comparative Examples 5-6 which used a lower amount of component D, the light conversion agent in the light conversion coatings of Examples 1-2 and 6-8 of the present invention, which used a higher amount of component D and were otherwise identical, had better solubility, resulting in UV light conversion coatings with better light conversion performance; and when the amount of component D (diluent) was 10 parts by mass or more, the UV light conversion coatings obtained in Examples 1-2 and 6-8 had essentially the same performance.

[0156] Compared to the light conversion coating of Comparative Example 7 which did not use component C, the light conversion coatings of Examples 1-2 and 4-5, which used 1-5 parts of component C and were otherwise identical, achieved significantly better adhesion.

[0157] - In addition, Example 1, which uses light conversion agent B1, achieved a higher light conversion efficiency than Example 2, which differed only in that it used light conversion agent B2; indicating that in the system of the present invention, benzotriazole fluorescent materials can result in slightly better light conversion efficiency of the prepared light conversion coating compared to rhodamine fluorescent materials.

[0158] The above description is merely an exemplary embodiment of the present invention. It should be noted that those skilled in the art can make improvements to the present invention without departing from the inventive concept, and all such improvements fall within the scope of protection of the present invention.

[0159] Table 1. Formulation composition of light conversion coatings in each embodiment and comparative example.

[0160]

[0161] Table 2 Comparison of light conversion performance between light conversion coatings and light conversion films

[0162]

[0163] Table 3 Performance of Light Conversion Coating

[0164]

Claims

1. A coating composition for forming a UV light conversion coating for photovoltaic cells, comprising, by weight: (A) 100 parts of polyurea precursor resin, which is a mixture of components AI and A-II: AI: Aspartic acid ester compounds or mixtures thereof represented by Formula I that are liquid at room temperature: in, X is an aliphatic group, such as an aliphatic chain aliphatic or alicyclic C2-C30 alkylene group; R1 and R2 may be the same as or different from each other and are each independently selected from C1-C4 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl; m is at least 2, for example 2-4, for example 2-3, preferably an integer of 2; and A-II: A liquid blocked isocyanate curing agent at room temperature, which is obtained by reacting an aliphatic polyol with an aliphatic polyisocyanate at a molar ratio r in which the isocyanate group of the polyisocyanate is in excess relative to the hydroxyl group of the polyol, to obtain a reaction product with terminal isocyanate groups, and then blocking the terminal isocyanate groups of the reaction product with a blocking agent. The molar ratio of the terminal isocyanate group blocked by the blocking agent in component A-II to the imino-NH- group in component AI is 1.20:1 to 1:1.

20. (B) 0.5 to 5 parts of UV light conversion agent; (C) 1 to 5 parts of adhesion promoter; (D) 10 to 100 parts of inert diluent.

2. The coating composition for forming a UV light conversion coating for photovoltaic cells as described in claim 1, wherein, In Formula I, X is selected from one of the following: methylene dicyclohexyl, such as 4,4'-methylene-dicyclohexyl; methylene-di(methylcyclohexyl), such as 4,4'-methylene-di(2-methylcyclohexyl), 4,4'-methylene-di(3-methylcyclohexyl); 1,6-hexadiyl; 2-methyl-1,5-pentadiyl; 3-methyl-1,5-pentadiyl; cyclohexyl, such as 1,2-cyclohexyl, 1,3-cyclohexyl, 1,4-cyclohexyl; 1-methyl-2,4-cyclohexyl; 1,3-cyclopentyl.

3. The coating composition for forming a UV light conversion coating for photovoltaic cells as described in claim 1, wherein, Component AI is selected from one or more of the following: N,N'-(methylenedi-4,1-cyclohexanediyl)diaspartic acid tetraethyl ester, N,N'-(methylenedi-4,1-cyclohexanediyl)diaspartic acid tetrabutyl ester, and N,N'-(methylenedi-(2-methyl-4,1-cyclohexanediyl))diaspartic acid tetraethyl ester.

4. The coating composition for forming a UV light conversion coating for photovoltaic cells as described in claim 1, wherein, The viscosity of component AI, measured at 25°C using a Brookfield viscometer at 0.5 rpm, ranges from 500 to 5000 cp, preferably 1000 to 1500 cp.

5. The coating composition for forming a UV light conversion coating for photovoltaic cells as described in claim 1, wherein, The aliphatic polyol is a chain aliphatic and / or alicyclic diol; Preferably, the diol is selected from one or more of the following: (1) Alkyl glycols, preferably selected from one or more of the following: C2-C20 glycols, such as C2-C10 glycols such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, cyclohexanediol, and cyclohexanediol; (2) An adduct of an alkylene glycol and an alkylene glycol with a different number of carbon atoms, wherein the alkylene oxide is preferably selected from one or more of ethylene oxide, propylene oxide, and butane oxide; (3) Polyepoxyalkane diol, preferably selected from one or more of polyethylene glycol, polypropylene glycol, polybutane glycol, polyethylene glycol-propylene glycol, polyethylene glycol-butane glycol, polypropylene glycol-butane glycol, and polyethylene glycol-propylene glycol-butane glycol; (4) Polyester diol, preferably a polycondensation product of C2-C20, such as C4-C10 aliphatic dicarboxylic acids and one or more diols selected from the alkylene diol, the adduct and the polyepoxyalkane diol; (5) Polycarbonate diol, preferably it is a reaction product of one or more diols selected from the alkylene diol, the epoxy alkane and the polyepoxy alkane diol with carbonate or phosgene or carbon dioxide; (6) Polylactone diol, preferably a reaction product obtained by ring-opening polymerization of one or more lactones selected from butyrolactone, valproic acid lactone, caprolactone, and decyl lactone using one or more diols selected from the alkylene glycol, the adduct and the polyepoxyalkane diol as an initiator. or (7) Any combination thereof; Preferably, the aliphatic polyol (e.g., polyether glycol, polyester glycol, polycarbonate glycol, polylactone glycol) has a hydroxyl value of 28 to 112 mg KOH / g, preferably 56 to 112 mg KOH / g.

6. The coating composition for forming a UV light conversion coating for photovoltaic cells as described in claim 1, wherein, The aliphatic polyisocyanate is an alicyclic polyisocyanate and / or a chain aliphatic polyisocyanate, preferably selected from one or more of the following: 4,4'-dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, cyclohexane dimethylene diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, norbornene diisocyanate, methylcyclohexyl diisocyanate, isophorone diisocyanate, and 1,6-hexamethylene diisocyanate.

7. The coating composition for forming a UV light conversion coating for photovoltaic cells as described in claim 1, wherein, The molar ratio r is 2.0-5.0, preferably 2.5-3.

5.

8. The coating composition for forming a UV light conversion coating for photovoltaic cells as described in claim 1, wherein, The blocking agent is selected from one or more of the following: methyl ethyl oxime, phenol, caprolactam, N-methylaniline, acetylacetone, sodium bisulfite, or ethyl mercaptan.

9. The coating composition for forming a UV light conversion coating for photovoltaic cells as claimed in claim 1, wherein the viscosity of component A-II, measured at 25°C using a Brookfield viscometer at 5 rpm, is in the range of 500-5000 cp, preferably 3000-4500 cp.

10. The coating composition for forming a UV light conversion coating for photovoltaic cells as claimed in claim 1, wherein the unsealing temperature of component A-II is 70-170°C, preferably 90-140°C, and more preferably 100-130°C.

11. The coating composition for forming a UV light conversion coating for photovoltaic cells as described in claim 1, wherein, The molar ratio of the terminal isocyanate group blocked by the blocking agent in component A-II to the imino-NH- group in component AI is 1.10:1 to 1.02:1, preferably 1.06:1 to 1.04:

1.

12. The coating composition for forming a UV light conversion coating for photovoltaic cells as claimed in claim 1, wherein the UV light conversion agent comprises one or more selected from: organic fluorescent materials, rare earth luminescent materials, and quantum dot luminescent materials; preferably benzotriazole fluorescent materials and rhodamine fluorescent materials, more preferably benzotriazole fluorescent materials.

13. The coating composition for forming a UV light conversion coating for photovoltaic cells as described in claim 1, wherein the adhesion promoter is a silane coupling agent, such as a compound or mixture thereof represented by YL-Si(OR)3, wherein Y is a group selected from vinyl, epoxy, amino, mercapto, and methacryloyloxy groups, L is a single bond or a C1-C10, for example, C1-C5 alkylene group, and R is a C1-C20 alkyl or aryl group, for example, the adhesion promoter is selected from one or more of the following: vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, 3-Glycidyl etheroxypropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane.

14. The coating composition for forming a UV light conversion coating for photovoltaic cells as described in claim 1, wherein, The amount of inert diluent is 10 to 30 parts by weight relative to 100 parts by weight of component A.

15. The coating composition for forming a UV light conversion coating for photovoltaic cells as described in claim 1, wherein, The diluent is selected from one or more of the following: ethyl acetate, butyl acetate, dimethyl carbonate, acetone, butanone, cyclohexanone, propylene carbonate, toluene, and xylene.

16. A UV light conversion coating, which is prepared from a coating composition for forming a UV light conversion coating for a photovoltaic cell as described in any one of claims 1-15.

17. A method for preparing a UV light conversion coating, comprising applying a coating composition for forming a UV light conversion coating for a photovoltaic cell as described in any one of claims 1-15 onto a substrate surface, and applying the coating composition onto the substrate surface and curing it by heating it to above the desealing temperature of components A-II.

18. A photovoltaic cell, comprising a UV light conversion coating as described in claim 17 formed on its surface.

19. A photovoltaic cell module, comprising a UV light conversion coating of claim 18 formed on the inner and / or outer surfaces of the front and / or back glass of the photovoltaic cell module.

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