Lightweight flexible photovoltaic module fire retardant coating and method of making same

Abstract

The present application relates to a kind of lightweight flexible photovoltaic module fire-retardant coating and its preparation method, including the following components: polyurethane modified acrylate, adhesion promoter, acid source monomer, carbon forming agent, gas source monomer, carbon source monomer, Organic filler, Inorganic filler, Initiator, Curing agent, Antioxidant, UV absorber, Light stabilizer.The present application is by adjusting the acid source, carbon source, gas source of fire-retardant coating, acid source and gas source are added on polymer main chain, try to reduce the influence on material physical property.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic modules, and in particular relates to a lightweight flexible photovoltaic module flame retardant coating and a preparation method thereof. Background Art

[0002] Lightweight, flexible photovoltaic modules are widely used on building roofs due to their light weight and bendability. However, for public buildings, higher flame retardancy is required. Module encapsulation materials are primarily polyolefins or polyesters, and therefore generally have an oxygen index below 23%, making them flammable. Furthermore, lightweight, flexible photovoltaic modules are prone to forming hot spots in the shadows of buildings, which can cause the polymer to reach flammable conditions, necessitating improvements in the material's flame retardancy.

[0003] Common methods include adding flame retardants to polymers or spraying flame retardant coatings on the surface. Since flame retardants are mainly acids and inorganic compounds, adding them directly to the polymer will significantly reduce the cohesive energy of the material, thereby reducing the reliability of the component material.

[0004] CN114409897A describes a fire-retardant coating made by doping phytic acid with a carbon nitride-polyaniline nanocomposite. Phytic acid is a bio-based material that is both flame-retardant and environmentally friendly. However, the epoxy resin matrix has limited long-term reliability, making it difficult to apply to composite materials.

[0005] CN111574874A uses double-bond modified acrylate to react and synthesize composite cellulose expandable graphite, which can effectively block flames and improve the flame retardancy of the product. However, its production process is complicated and it contains conductive graphite, making it unsuitable for outdoor electrical appliances.

[0006] In CN117986987B, phosphorus is doped into bio-based porous carbon molecules to improve the flame retardancy of the carbonized structure. Magnesium, a flame-retardant element, is also doped into the ZIF-8 structure. Both have porous structures, allowing for tighter bonding with the composite resin. This method primarily synthesizes inorganic doping components to improve the temperature resistance of the flame-retardant layer, but its high cost makes it unsuitable for flame-retardant coatings on photovoltaic materials. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a lightweight flexible flame-retardant coating for photovoltaic modules and a preparation method thereof. By formulating the acid source, carbon source and gas source of the flame-retardant coating, the acid source and gas source are added to the polymer main chain to minimize the impact on the physical properties of the material.

[0008] The present invention provides a lightweight flexible photovoltaic module flame retardant coating, which comprises the following components in parts by weight:

[0009] 15-40 parts of polyurethane modified acrylate;

[0010] 5-10 parts of adhesion promoter;

[0011] 10-15 parts of acid source monomer;

[0012] 10-15 parts of carbon forming agent;

[0013] 3~5 parts of gas source monomer;

[0014] 20-25 parts of carbon source monomer;

[0015] 1~3 parts of organic filler;

[0016] 1-15 parts of inorganic filler;

[0017] 0.5~1 part of initiator;

[0018] 2~4 parts of curing agent;

[0019] 0.3-0.8 parts of antioxidant;

[0020] UV absorber 0.5-1 part;

[0021] Light stabilizer 0.2-0.5 parts;

[0022] The acid source monomer is obtained by reacting acrylic acid phosphate containing a double bond with melamine;

[0023] The carbon-forming agent is obtained by reacting a reaction monomer with polyethylene glycol.

[0024] Preferably, the double-bond-containing acrylic acid phosphate includes one or more of 2-hydroxyethyl methacrylate phosphate, di[2-(methacryloyloxy)ethyl]phosphate, and 2-methyl-2-acrylate-2-hydroxyethyl phosphate.

[0025] Preferably, the reactive monomers include one or more of 4-glycidyl styrene oxide, diglycidyl acrylate, and glycidyl methacrylate.

[0026] Preferably, the polyethylene glycol includes one or more of PEG200, PEG300, and PEG400.

[0027] Preferably, the adhesion promoter includes one or more of 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate.

[0028] Preferably, the gas source monomer includes one or more of 1,3,5-tris(2-hydroxyethyl)isocyanurate and tris(2-acryloyloxyethyl)isocyanurate; and the carbon source monomer includes one or more of pentaerythritol, dipentaerythritol and hexahydroxy alcohol.

[0029] Preferably, the organic filler comprises one or more of dibutyl vinyl borate, methyl imino diethyl vinyl borate.

[0030] Preferably, the inorganic filler comprises one or more of titanium dioxide, aluminum hydroxide.

[0031] Preferably, the initiator comprises one or more of benzoyl peroxide, t-butyl peroctoate, t-butyl peroxy diethylacetate.

[0032] Preferably, the curing agent comprises one or more of dicyandiamide, isoforone diamine, diaminodiphenyl sulfone. In particular, dicyandiamide not only can cure the epoxy group, but also itself can be a gas source, making the flame-retardant coating foam faster.

[0033] Preferably, the antioxidant comprises one or more of hindered phenolic antioxidant 1076, 1098, 1010.

[0034] Preferably, the UV absorber comprises one or more of hindered phenolic or triazine UV absorber UV1164, UV1577, UV400.

[0035] Preferably, the light stabilizer comprises one or more of benzotriazole light stabilizer UV1130, UV928, UV123.

[0036] The present application also provides a preparation method of a lightweight flexible photovoltaic module flame-retardant coating, comprising the following steps:

[0037] (1) adding phosphoric acid acrylate containing double bonds and melamine in a molar ratio of 2-4:1 to an organic solvent, reacting at 50-80°C for 5-10h under a nitrogen atmosphere, evaporating to remove the organic solvent, and obtaining an acid source monomer;

[0038] (2) mixing the reaction monomer with polyethylene glycol in a molar ratio of 1-1.5:1, reacting at 50-80°C for 1-2h under a nitrogen atmosphere, and obtaining a carbon-forming agent;

[0039] (3) mixing the acid source monomer, the carbon-forming agent, and other components in a proportion at room temperature, then vacuumizing to remove oxygen, and obtaining a lightweight flexible photovoltaic module flame-retardant coating.

[0040] Preferably, the organic solvent in step (1) is N,N-dimethylformamide and acetic acid in a volume ratio of 1:1.

[0041] Preferably, a polymerization inhibitor is also added in the reaction in step (1), and the amount of the polymerization inhibitor added is 0.1%-0.5% of the total mass of the reaction system.

[0042] Preferably, a polymerization inhibitor and a catalyst are further added during the reaction in step (2), wherein the amount of the polymerization inhibitor added is 0.1%-0.5% of the total mass of the reaction system, and the amount of the catalyst added is 1%-2% of the total mass of the reaction system.

[0043] Preferably, the polymerization inhibitor is hydroquinone; and the catalyst is triethylamine.

[0044] The present invention also provides a method for using a lightweight flexible photovoltaic module flame retardant coating, comprising the following steps:

[0045] The flame-retardant coating of the lightweight flexible photovoltaic module is applied to the composite material, covered with a PET film and flattened, followed by a two-stage thermal curing process, i.e. the temperature is first raised to 50-55°C and maintained for 10-20 minutes, then raised to 65-70°C and maintained for 10-20 minutes; finally, in a laminator, the temperature is raised to 130-150°C and maintained for 10-20 minutes to completely cure the coating.

[0046] Beneficial effects

[0047] (1) In the present invention, in the presence of a polymerization inhibitor, melamine and acrylic acid phosphate containing double bonds undergo an esterification reaction to generate melamine phosphonate, thereby obtaining a high molecular weight acid source monomer; the high molecular weight acid source monomer itself has a high molecular weight, low mobility, low acidity at room temperature, and stable properties. When added to a polymer system, the physical properties and flame retardant properties are slightly reduced, thereby increasing the stability of the phosphorus-containing polymer.

[0048] (2) In the present invention, in the presence of an inhibitor, the reaction monomer reacts with polyethylene glycol to generate a carbon-forming agent. The carbon-forming agent has low mobility and can maintain performance stability for a long time, and is suitable for use at a maximum operating temperature of 70°C for photovoltaic modules.

[0049] (3) The gas source monomer of the present invention is on the main chain of the polymer molecular chain, and the flame retardant coating has a long service life.

[0050] (4) The present invention adopts a two-stage thermal curing process during use to increase the uniformity of the carbon forming agent and the acid source monomer, and gradually increase the molecular weight of the flame retardant coating. The final curing is to increase the physical strength of the coating, so that the coating has strength, weather resistance and flame retardancy at the same time. DETAILED DESCRIPTION

[0051] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0052] The reagents, methods and apparatus employed in the present application are conventional in the art unless otherwise specified.

[0053] Table 1 Acid source monomer formula

[0054]

[0055] The preparation method of the acid source monomer comprises:

[0056] The acrylic acid phosphate containing double bonds and melamine are added into a mixed solvent of N,N-dimethylformamide and acetic acid in a volume ratio of 1:1 (the weight fraction of the reaction raw material is the same as the mass fraction of the solvent) in a molar ratio of 3:1, 0.2wt% of hydroquinone based on the total mass of the reaction system is added, and the mixture is reacted at 65°C for 6h under a nitrogen atmosphere. The solvent is evaporated to obtain the acid source monomer.

[0057] Table 2 Carbon forming agent formula

[0058]

[0059] The preparation method of the carbon forming agent comprises:

[0060] The reaction monomer and polyethylene glycol are mixed in a molar ratio of 1.05:1, 0.2wt% of hydroquinone based on the total mass of the reaction system and 1wt% of triethylamine are added, and the mixture is reacted at 75°C for 1h under a nitrogen atmosphere to obtain the carbon forming agent.

[0061] Table 3 Lightweight flexible photovoltaic module flame retardant coating formula (example)

[0062]

[0063] Table 4 Lightweight flexible photovoltaic module flame retardant coating formula (comparative example)

[0064]

[0065] The preparation method of the lightweight flexible photovoltaic module flame retardant coating comprises:

[0066] The acid source monomer, carbon forming agent and other components are mixed at room temperature according to the proportion, and then vacuumized to remove oxygen to obtain the lightweight flexible photovoltaic module flame retardant coating.

[0067] The use method of the lightweight flexible photovoltaic module flame retardant coating comprises:

[0068] Using a screw or silk screen, the flame-retardant coating of lightweight flexible photovoltaic modules is applied to the PP composite material after corona treatment (coating thickness > 100μm), covered with a PET film and flattened, followed by a two-stage thermal curing, that is, the temperature is first raised to 50℃, maintained for 10 minutes, then raised to 65℃, maintained for 10 minutes; finally, in a laminator, the temperature is raised to 140℃ and maintained for 10 minutes to completely cure the coating.

[0069] Table 5 Test results of flame retardant coatings for lightweight flexible photovoltaic modules (Examples 1-5)

[0070]

[0071] Table 6 Test results of flame retardant coatings for lightweight flexible photovoltaic modules (Examples 6-9)

[0072]

[0073] Table 7 Test results of flame retardant coatings for lightweight flexible photovoltaic modules (Comparative Examples 1-5)

[0074]

[0075] Table 8 Test results of flame retardant coatings for lightweight flexible photovoltaic modules (Comparative Examples 6-9)

[0076]

[0077] From the above test results, we can see that:

[0078] 1. As can be seen from Examples 1 and 2, A2 has a low phosphorus content, and therefore its oxygen index is relatively low. Since phosphorus-containing acrylic acid is also an adhesion promoter, its adhesion decreases as its phosphorus content decreases.

[0079] 2. It can be seen from Example 1 and Comparative Example 1 that an acid source is essential. Without an acid source, the oxygen index is greatly reduced, the combustion flame spreads easily, the oxygen index is high, and the combustion level is low.

[0080] 3. As can be seen from Example 1 and Comparative Examples 2 and 3, the reduction of carbon forming agent and gas source monomer improves the wear resistance of the coating, but its combustion flame spreads easily and the heat insulation capacity decreases. Therefore, the combustion flame spreads easily, resulting in a lower combustion grade.

[0081] 4. Comparative Examples 4 and 8 show that reducing the reactive monomer or curing agent content leads to reduced coating adhesion and a tendency for the polymer to decompose more easily, resulting in poorer flame retardancy. Comparative Example 8 demonstrates that dicyandiamide acts not only as a curing agent but also as a gas source, making flame spread more easily and resulting in a lower flame retardancy rating.

[0082] 5. As can be seen from Comparative Examples 5 and 6, as the amount of inorganic filler decreases, its carbon-forming ability decreases, and thus the flame retardancy deteriorates. Titanium dioxide can act as a Lewis acid source at high temperatures to synergistically form carbon.

[0083] 6. If organic boron is not added in Comparative Example 7, its combustion level will be reduced. At high temperatures, the boron element can form boric acid, which serves as the core of the gas phase flame retardant, so its oxygen index is greatly reduced.

[0084] 7. In Comparative Example 9, there is no problem with flame retardancy, but the large addition of inorganic aluminum hydroxide causes the product's resin adhesion to deteriorate.

[0085] 8. It can be seen from Examples 3 and 4 that the increase in phosphorus content increases the oxygen index of the material, but the coating adhesion decreases accordingly.

[0086] 9. It can be seen from Examples 4 and 5 that the increase of carbon forming agent will make the thermal insulation number of the material lower, and therefore the flame spread index i is lower.

[0087] 10. It can be seen from Examples 5 and 6 that the gas source monomer contains polar groups, and as the content of polar groups increases, the adhesion of the material will become better.

[0088] 11. As can be seen from Examples 6 and 7, tris(2-acryloyloxyethyl)isocyanurate has a lower adhesion than 1,3,5-tris(2-hydroxyethyl)isocyanurate due to its reduced hydroxyl content.

[0089] 12. It can be seen from Examples 7 and 8 that the addition of reactive monomers can increase the molecular weight of the material, making the oxygen index of the flame retardant coating higher, and improving both adhesion and wear resistance.

[0090] 13. It can be seen from Examples 8 and 9 that although increasing the content of aluminum hydroxide improves the carbonization of the material and reduces the flame spread index, its coating adhesion is also reduced.

Claims

1. A lightweight, flexible flame-retardant coating for photovoltaic modules, characterized by: By weight, it is composed of the following components: 15-40 parts of polyurethane modified acrylate; 5-10 parts of adhesion promoter; 10-15 parts of acid source monomer; 10-15 parts of carbon forming agent; 3~5 parts of gas source monomer; 20-25 parts of carbon source monomer; 1~3 parts of organic filler; 1-15 parts of inorganic filler; 0.5~1 part of initiator; 2~4 parts of curing agent; 0.3-0.8 parts of antioxidant; UV absorber 0.5-1 part; Light stabilizer 0.2-0.5 parts; The acid source monomer is obtained by reacting acrylic acid phosphate containing a double bond with melamine; The carbon-forming agent is obtained by reacting a reaction monomer with polyethylene glycol; The double-bond acrylic acid phosphate includes one or more of 2-hydroxyethyl methacrylate phosphate, di[2-(methacryloyloxy)ethyl]phosphate, and 2-methyl-2-acrylate-2-hydroxyethyl phosphate; The reactive monomers include one or more of 4-glycidyl styrene oxide, diglycidyl acrylate, and glycidyl methacrylate; The gas source monomer includes one or more of 1,3,5-tris(2-hydroxyethyl)isocyanurate and tris(2-acryloyloxyethyl)isocyanurate.

2. The flame-retardant coating for lightweight flexible photovoltaic modules according to claim 1, characterized in that: The adhesion promoter includes one or more of 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate.

3. The flame-retardant coating for lightweight flexible photovoltaic modules according to claim 1, characterized in that: The carbon source monomer includes one or more of pentaerythritol, dipentaerythritol, and hexahydroxy alcohol.

4. The flame-retardant coating for lightweight flexible photovoltaic modules according to claim 1, characterized in that: The organic filler includes one or more of vinyl borate dibutyl ester and vinyl borate methyliminodiacetate; the inorganic filler includes one or more of titanium dioxide and aluminum hydroxide.

5. The flame-retardant coating for lightweight flexible photovoltaic modules according to claim 1, characterized in that: The initiator includes one or more of benzoyl peroxide, tert-butyl peroxyoctanoate, and tert-butyl peroxydiethylacetate.

6. The flame-retardant coating for lightweight flexible photovoltaic modules according to claim 1, characterized in that: The curing agent includes one or more of dicyandiamide, isophorone diamine, and diaminodiphenyl sulfone.

7. The flame-retardant coating for lightweight flexible photovoltaic modules according to claim 1, characterized in that: The antioxidant includes one or more of the hindered phenol antioxidants 1076, 1098, and 1010; the UV absorber includes one or more of the hindered phenol or triazine UV absorbers UV1164, UV1577, and UV400; and the light stabilizer includes one or more of the benzotriazole light stabilizers UV1130, UV928, and UV123.

8. A method for preparing the flame-retardant coating for a lightweight flexible photovoltaic module according to claim 1, comprising the following steps: (1) adding a double-bond acrylic acid phosphate and melamine in a molar ratio of 2-4:1 to an organic solvent, reacting at 50-80°C for 5-10 hours under a nitrogen atmosphere, and evaporating the organic solvent to obtain an acid source monomer; (2) mixing the reaction monomer and polyethylene glycol in a molar ratio of 1-1.5:1, reacting at 50-80°C for 1-2 hours under a nitrogen atmosphere to obtain a carbon-forming agent; (3) The acid source monomer, carbon forming agent and other components are mixed at room temperature according to a proportion, and then vacuumed to remove oxygen to obtain a lightweight flexible photovoltaic module flame retardant coating.

Images