A photovoltaic encapsulant material and method of making the same

Abstract

The application discloses a kind of photovoltaic packaging materials and preparation method thereof, the photovoltaic packaging material, by weight parts, its raw material includes: oligomer dihydric alcohol 20-50 parts, curing agent 1-5 parts, chain extender 0-2 parts, catalyst 0-2 parts, organic solvent 10-40 parts, leveling agent 0.05-1 part, defoaming agent 0.1-1 part, the TPU film prepared in the application compared with traditional EVA film, with good light transmission, high transparency, weather resistance, no yellowing advantage, in addition, it also has certain hydrolysis resistance, impact resistance and tensile strength, the film is mainly used for the packaging material of solar cell, enhances the life of solar cell, improves the light energy utilization efficiency and power generation efficiency of solar photovoltaic cell.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, classified under H01L31 / 048, and specifically to a photovoltaic encapsulation material and its preparation method. Background Technology

[0002] With the gradual development of photovoltaic technology, the performance requirements for photovoltaic module encapsulation materials are becoming increasingly stringent. Currently, there are many types of commonly used solar photovoltaic module encapsulation materials, including polydimethylsiloxane (PDMS), thermoplastic polyolefin (TPO), fluorinated resins, polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer (EVA), and thermoplastic polyurethane (TPU). Among them, TPU is known for its excellent mechanical properties and abrasion resistance, as well as good toughness, oil resistance, and corrosion resistance, and its applications are becoming increasingly widespread. However, TPU has poor weather resistance; its mechanical and optical properties will be severely degraded after long-term operation at high temperatures or in harsh environments, which limits its use.

[0003] Patent CN104231204B discloses a thermoplastic polyurethane elastomer for solar cells and its preparation method. The TPU film prepared by it has high transparency, good light transmittance, resistance to yellowing, high melting point and good adhesion strength, but the weather resistance, heat resistance and mechanical properties of its TPU film need to be improved. Summary of the Invention

[0004] To address the aforementioned problems, the first aspect of this invention provides a photovoltaic encapsulation material, comprising, by weight, the following raw materials: 20-50 parts of oligomeric diol, 1-5 parts of curing agent, 0-2 parts of chain extender, 0-2 parts of catalyst, 10-40 parts of organic solvent, 0.05-1 part of leveling agent, and 0.1-1 part of defoamer.

[0005] More preferably, the photovoltaic encapsulation material, by weight, comprises the following raw materials: 30-50 parts of oligomeric diol, 2-4 parts of curing agent, 1-2 parts of chain extender, 1-2 parts of catalyst, 20-40 parts of organic solvent, 0.05-1 part of leveling agent, and 0.1-1 part of defoamer.

[0006] More preferably, the photovoltaic encapsulation material, by weight, comprises the following raw materials: 40 parts of oligomeric diol, 3.5 parts of curing agent, 1.2 parts of chain extender, 1.5 parts of catalyst, 30 parts of organic solvent, 0.08 parts of leveling agent, and 0.8 parts of defoamer.

[0007] More preferably, the catalyst is at least one of dibutyltin thiolate, dimethyltin dilaurate, dibutyltin dilaurate, stannous octoate, or dibutyltin diacetate, and zinc naphthenate; the organic solvent is at least one of N,N-dimethylformamide, butyl acetate, xylene, cyclohexanone, acetone, butanone, N-methylpyrrolidone, dioxane, pyridine or methyl isobutyl ketone, toluene, xylene, and chlorobenzene; the leveling agent includes at least one of polyacrylic acid, cellulose acetate butyrate, organically modified siloxane, fluorinated olefin, acrylic acid, cellulose acetate butyrate, and polyether-modified organosilicon; and the defoamer includes at least one of polyether, higher alcohol, polysiloxane, and polyether-modified organosilicon.

[0008] More preferably, the catalyst is zinc naphthenate, the organic solvent is xylene, cyclohexanone and butyl acetate in a mass ratio of 1:1:1, the leveling agent is polyether-modified silicone, and the defoamer is a polysiloxane.

[0009] Preferably, the oligomeric diol is a polyester diol and / or a polyether diol.

[0010] More preferably, the polyester diol includes at least one of polyhexanediol adipate, polybutylene adipate, and polypropylene adipate, and the polyether diol includes at least one of polyethylene glycol, polypropylene glycol, and polytetrahydrofuran ether diol.

[0011] More preferably, the oligomeric diol is a polyester diol and a polyether diol, wherein the polyester diol is polyhexamethylene adipate and the polyether diol is polytetrahydrofuran ether diol.

[0012] Preferably, the oligomeric diol is a polyester diol and a polyether diol, with a weight ratio of 1:(2-5).

[0013] More preferably, the oligomeric diol is a polyester diol and a polyether diol, with a weight ratio of 1:(2-3).

[0014] More preferably, the oligomeric diol is a polyester diol and a polyether diol, with a weight ratio of 1:3.

[0015] Preferably, the molecular weight of the polyester diol is 2000-4000 g / mol, and the molecular weight of the polyether diol is 1000-3000 g / mol.

[0016] More preferably, the molecular weight of the polyester diol is 3000 g / mol, and the molecular weight of the polyether diol is 2000 g / mol.

[0017] Preferably, the curing agent includes at least one of hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane-4,4'-diisocyanate, toluene diisocyanate, phenyldimethylmethylene diisocyanate, tetramethylphenyldimethylmethylene diisocyanate, naphthalene-1,5-diisocyanate, IPDI trimer, and HDI trimer.

[0018] Preferably, the curing agent is a mixture of IPDI trimer and HDI trimer, with a mass ratio of (2-5):1.

[0019] More preferably, the curing agent is a mixture of IPDI trimer and HDI trimer, with a mass ratio of (2-3):1.

[0020] More preferably, the curing agent is a mixture of IPDI trimer and HDI trimer in a mass ratio of 3:1.

[0021] Preferably, the chain extender is a fluorinated chain extender and a small molecule diol.

[0022] More preferably, the fluorinated chain extender includes at least one of trifluoroethyl acrylate, hexafluorobutyl acrylate, trifluoroethyl methacrylate, ethyl 2-(2,4-difluorophenyl)-2-hydroxyethyliminocyanide, and 4,4'-(hexafluoroisopropylidene)diphenol, and the small molecule diol includes at least one of 1,4-butanediol, ethylene glycol, propylene glycol, diethylene glycol, and neopentyl glycol.

[0023] More preferably, the fluorinated chain extender is 4,4'-(hexafluoroisopropylidene)diphenol, and the small molecule diol is 1,4-butanediol.

[0024] Preferably, the mass ratio between the fluorinated chain extender and the small molecule diol is (1-3):(3-6).

[0025] More preferably, the mass ratio between the fluorinated chain extender and the small molecule diol is (1-2):(3-5).

[0026] More preferably, the mass ratio between the fluorinated chain extender and the small molecule diol is 2:4.

[0027] A second aspect of this invention provides a method for preparing a photovoltaic encapsulation material, comprising the following steps:

[0028] S1: Preparation of TPU film;

[0029] Add the curing agent, oligomeric diol, and catalyst to the reaction apparatus according to the weight parts, and react at 60-70℃ for 1-3 hours. Then add the solvent, raise the temperature to 80-100℃, stabilize the molar ratio of NCO / OH in the system, add the chain extender, react for 2-2.5 hours, add the defoamer and leveling agent, load into the mold, roll press, and dry to form a TPU film.

[0030] Preferably, the molar ratio of NCO / OH in step S1 is (1.4-1.8):1.

[0031] More preferably, the molar ratio of NCO / OH is (1.5-1.7):1.

[0032] More preferably, the molar ratio of NCO / OH is 1.6:1.

[0033] The applicant discovered that while adding polyhexyl adipate alone improves the UV resistance of TPU films, it reduces their light transmittance. This is presumably because polyhexyl adipate contains a large number of ester groups, which easily crystallize, resulting in low light transmittance. Based on this, the applicant added polytetrahydrofuran ether glycol, making the weight ratio of polyhexyl adipate to polytetrahydrofuran ether glycol 1:(2-3), which improved the light transmittance of the TPU film. This is presumably because the intermolecular forces of polytetrahydrofuran ether glycol are relatively weak, making it easy to produce random arrangement and less prone to crystallization, thus improving light transmittance. However, the weather resistance still needs to be improved.

[0034] To address the weather resistance issue, the applicant added 4,4'-(hexafluoroisopropylidene)diphenol and 1,4-butanediol, limiting their mass ratio to (1-2):(3-5). This not only resulted in the TPU film having a yellowing index below 2 after 200 hours of UV irradiation, but also, under conditions of 105℃±5℃ and relative humidity below 50%, a yellowing index decrease of only 2 after 500 hours of testing. The applicant hypothesizes that as the fluorine content increases, the microphase separation in the system becomes more pronounced, indicating that the introduction of fluorine is detrimental to the material's transparency. Therefore, increasing the fluorine content increases incompatibility and decreases light transmittance. However, increasing the fluorine content enhances UV resistance, heat resistance, and yellowing resistance. Therefore, while ensuring certain weather resistance, heat resistance, and yellowing resistance, adding IPDI and HDI trimers at a mass ratio of (2-3):1 allows the two curing agents to work synergistically, resulting in a disordered system structure, reduced crystallinity, increased transparency, and moderate crosslinking, significantly improving impact resistance and tensile strength.

[0035] In addition, the applicant unexpectedly discovered that as the molar ratio of NCO / OH in the system gradually increases, the tensile strength of the film gradually increases. However, if the molar ratio is too high, the excess -NCO will produce crosslinking or branching, which weakens the tensile strength. When the molar ratio of NCO / OH in the system is (1.5-1.7):1, the degree of crosslinking of the system is moderate, which enhances the tensile strength of the film and also improves the hydrolysis resistance to a certain extent.

[0036] Beneficial effects: Compared with traditional EVA films, the TPU film prepared by this invention has the advantages of good light transmittance, high transparency, good weather resistance, and non-yellowing. In addition, it also has certain resistance to hydrolysis, impact resistance, and tensile strength. This film is mainly used as an encapsulation material for solar cells, which enhances the lifespan of solar cells and improves the light energy utilization efficiency and power generation efficiency of solar photovoltaic cells.

[0037] The following detailed description, in conjunction with embodiments, illustrates the TPU film, its preparation method, and its application in photovoltaic modules provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0038] Example

[0039] Example 1

[0040] A photovoltaic encapsulation material, by weight, comprises the following raw materials: 40 parts of oligomeric diol, 3.5 parts of curing agent, 1.2 parts of chain extender, 1.5 parts of catalyst, 30 parts of organic solvent, 0.08 parts of leveling agent, and 0.8 parts of defoamer.

[0041] The oligomeric diol is polyhexanediol adipate and polytetrahydrofuran ether diol in a weight ratio of 1:3. The molecular weight of the polyhexanediol adipate is 3000 g / mol, and the molecular weight of the polytetrahydrofuran ether diol is 2000 g / mol. The polyhexanediol adipate was purchased from Jinjinle Chemical Co., Ltd., and the polytetrahydrofuran ether diol was purchased from Jinan Guangyu Chemical Co., Ltd.

[0042] The curing agent is a mixture of IPDI trimer and HDI trimer in a mass ratio of 3:1. The IPDI trimer is purchased from Evonik Germany, model VESTANAT T1890, and the HDI trimer is purchased from Covestro, product number N3390 BA / SN.

[0043] The chain extender is a fluorinated chain extender and a small molecule diol, and the mass ratio of the fluorinated chain extender to the small molecule diol is 2:4.

[0044] The fluorinated chain extender is 4,4'-(hexafluoroisopropylidene)diphenol, and the small molecule diol is 1,4-butanediol. The 4,4'-(hexafluoroisopropylidene)diphenol was purchased from Wuhan Kanos Technology Co., Ltd., with product number 8598479.

[0045] The organic solvent is xylene, cyclohexanone, and butyl acetate, with a mass ratio of 1:1:1.

[0046] The catalyst is zinc naphthenate.

[0047] The leveling agent is a polyether-modified silicone, purchased from BYK Chemicals, model BYK-333.

[0048] The defoamer is a polysiloxane, purchased from BYK Chemicals, model number BYK-025.

[0049] This embodiment also provides a method for preparing a photovoltaic encapsulation material, including the following steps:

[0050] S1: Preparation of TPU film;

[0051] The curing agent, oligomeric diol, and catalyst are added to the reaction apparatus according to the weight parts and reacted at 65°C for 2 hours. Then, the solvent is added and the temperature is raised to 90°C. At this time, the molar ratio of NCO / OH is 1.6:1. After adding the chain extender and reacting for 2 hours, the defoamer and leveling agent are added, and the mixture is loaded into a mold, rolled, and dried to form a TPU film.

[0052] Example 2

[0053] A photovoltaic encapsulation material, by weight, comprises the following raw materials: 40 parts of oligomeric diol, 3.5 parts of curing agent, 1.2 parts of chain extender, 1.5 parts of catalyst, 30 parts of organic solvent, 0.08 parts of leveling agent, and 0.8 parts of defoamer.

[0054] The oligomeric diol is polyhexanediol adipate and polytetrahydrofuran ether diol in a weight ratio of 1:2. The molecular weight of the polyhexanediol adipate is 3000 g / mol, and the molecular weight of the polytetrahydrofuran ether diol is 2000 g / mol. The polyhexanediol adipate was purchased from Jinjinle Chemical Co., Ltd., and the polytetrahydrofuran ether diol was purchased from Jinan Guangyu Chemical Co., Ltd.

[0055] The curing agent is a mixture of IPDI trimer and HDI trimer in a mass ratio of 2:1. The IPDI trimer was purchased from Evonik Germany, model VESTANAT T1890, and the HDI trimer was purchased from Covestro, product number N3390 BA / SN.

[0056] The chain extender is a fluorinated chain extender and a small molecule diol, and the mass ratio of the fluorinated chain extender to the small molecule diol is 2:4.

[0057] The fluorinated chain extender is 4,4'-(hexafluoroisopropylidene)diphenol, and the small molecule diol is 1,4-butanediol. The 4,4'-(hexafluoroisopropylidene)diphenol was purchased from Wuhan Kanos Technology Co., Ltd., product number 8598479.

[0058] The organic solvent is xylene, cyclohexanone, and butyl acetate, with a mass ratio of 1:1:1.

[0059] The catalyst is zinc naphthenate.

[0060] The leveling agent is a polyether-modified silicone, purchased from BYK Chemicals, model BYK-333.

[0061] The defoamer is a polysiloxane, purchased from BYK Chemicals, model number BYK-025.

[0062] This embodiment also provides a method for preparing a photovoltaic encapsulation material, including the following steps:

[0063] S1: Preparation of TPU film;

[0064] The curing agent, oligomeric diol, and catalyst are added to the reaction apparatus according to the weight parts and reacted at 65°C for 2 hours. Then, the solvent is added and the temperature is raised to 90°C. At this time, the molar ratio of NCO / OH is 1.6:1. After adding the chain extender and reacting for 2 hours, the defoamer and leveling agent are added, and the mixture is loaded into a mold, rolled, and dried to form a TPU film.

[0065] Example 3

[0066] A photovoltaic encapsulation material, by weight, comprises the following raw materials: 40 parts of oligomeric diol, 3.5 parts of curing agent, 1 part of chain extender, 1.5 parts of catalyst, 30 parts of organic solvent, 0.08 parts of leveling agent, and 0.8 parts of defoamer.

[0067] The oligomeric diol is composed of polyhexanediol adipate and polytetrahydrofuran ether diol in a weight ratio of 1:3. The molecular weight of the polyhexanediol adipate is 3000 g / mol, and the molecular weight of the polytetrahydrofuran ether diol is 2000 g / mol. The polyhexanediol adipate was purchased from Jinjinle Chemical Co., Ltd., and the polytetrahydrofuran ether diol was purchased from Jinan Guangyu Chemical Co., Ltd.

[0068] The curing agent is a mixture of IPDI trimer and HDI trimer in a mass ratio of 3:1. The IPDI trimer was purchased from Evonik Germany, model VESTANAT T1890, and the HDI trimer was purchased from Covestro, product number N3390 BA / SN.

[0069] The chain extender is a fluorinated chain extender and a small molecule diol, and the mass ratio between the fluorinated chain extender and the small molecule diol is 1:5.

[0070] The fluorinated chain extender is 4,4'-(hexafluoroisopropylidene)diphenol, and the small molecule diol is 1,4-butanediol. The 4,4'-(hexafluoroisopropylidene)diphenol was purchased from Wuhan Kanos Technology Co., Ltd., product number 8598479.

[0071] The organic solvent is xylene, cyclohexanone, and butyl acetate, with a mass ratio of 1:1:1.

[0072] The catalyst is zinc naphthenate.

[0073] The leveling agent is a polyether-modified silicone, purchased from BYK Chemicals, model BYK-333.

[0074] The defoamer is a polysiloxane, purchased from BYK Chemicals, model number BYK-025.

[0075] This embodiment also provides a method for preparing a photovoltaic encapsulation material, including the following steps:

[0076] S1: Preparation of TPU film;

[0077] The curing agent, oligomeric diol, and catalyst are added to the reaction apparatus according to the weight parts and reacted at 65°C for 2 hours. Then, the solvent is added and the temperature is raised to 90°C. At this time, the molar ratio of NCO / OH is 1.6:1. After adding the chain extender and reacting for 2 hours, the defoamer and leveling agent are added, and the mixture is loaded into a mold, rolled, and dried to form a TPU film.

[0078] Example 4

[0079] A photovoltaic encapsulation material, by weight, comprises the following raw materials: 40 parts of oligomeric diol, 3.5 parts of curing agent, 1.2 parts of chain extender, 1.5 parts of catalyst, 30 parts of organic solvent, 0.08 parts of leveling agent, and 0.8 parts of defoamer.

[0080] The oligomeric diol is composed of polyhexanediol adipate and polytetrahydrofuran ether diol in a weight ratio of 1:3. The molecular weight of the polyhexanediol adipate is 3000 g / mol, and the molecular weight of the polytetrahydrofuran ether diol is 2000 g / mol. The polyhexanediol adipate was purchased from Jinjinle Chemical Co., Ltd., and the polytetrahydrofuran ether diol was purchased from Jinan Guangyu Chemical Co., Ltd.

[0081] The curing agent is a mixture of IPDI trimer and HDI trimer in a mass ratio of 2:1. The IPDI trimer was purchased from Evonik Germany, model VESTANAT T1890, and the HDI trimer was purchased from Covestro, product number N3390 BA / SN.

[0082] The chain extender is a fluorinated chain extender and a small molecule diol, and the mass ratio of the fluorinated chain extender to the small molecule diol is 1:3.

[0083] The fluorinated chain extender is 4,4'-(hexafluoroisopropylidene)diphenol, and the small molecule diol is 1,4-butanediol. The 4,4'-(hexafluoroisopropylidene)diphenol was purchased from Wuhan Kanos Technology Co., Ltd., product number 8598479.

[0084] The organic solvent is xylene, cyclohexanone, and butyl acetate, with a mass ratio of 1:1:1.

[0085] The catalyst is zinc naphthenate.

[0086] The leveling agent is a polyether-modified silicone, purchased from BYK Chemicals, model BYK-333.

[0087] The defoamer is a polysiloxane, purchased from BYK Chemicals, model number BYK-025.

[0088] This embodiment also provides a method for preparing a photovoltaic encapsulation material, including the following steps:

[0089] S1: Preparation of TPU film;

[0090] The curing agent, oligomeric diol, and catalyst are added to the reaction apparatus according to the weight parts and reacted at 65°C for 2 hours. Then, the solvent is added and the temperature is raised to 90°C. At this time, the molar ratio of NCO / OH is 1.6:1. After adding the chain extender and reacting for 2 hours, the defoamer and leveling agent are added, and the mixture is loaded into a mold, rolled, and dried to form a TPU film.

[0091] Comparative Example 1

[0092] Only polytetrahydrofuran ether diol was added, and the mass ratio of 4,4'-(hexafluoroisopropylidene)diphenol to 1,4-butanediol was changed to 4:3, with the rest being the same as in Example 1.

[0093] Comparative Example 2

[0094] Only 4,4'-(hexafluoroisopropylidene)diphenol was added, and the mass ratio of polyhexamethylene adipate to polytetrahydrofuran ether diol was changed to 1:5, with the rest being the same as in Example 1.

[0095] Comparative Example 3

[0096] The mass ratio of IPDI and HDI trimers was changed to 5:1, and the catalyst zinc naphthenate was replaced with dimethyltin dilaurate. The rest was the same as in Example 1.

[0097] Comparative Example 4

[0098] The mass ratio of polyhexamethylene adipate and polytetrahydrofuran ether diol was changed to 2:5, and the mass ratio of 4,4'-(hexafluoroisopropylidene)diphenol and 1,4-butanediol was changed to 4:1. The rest was the same as in Example 1.

[0099] Comparative Example 5

[0100] The NCO / OH molar ratio was changed to 2:1, and the mass ratio of IPDI and HDI trimers was changed to 5:1. The rest was the same as in Example 1.

[0101] Performance Evaluation

[0102] (1) Transmittance test: The transmittance was tested using a HACH UV-9930 UV-Vis spectrophotometer according to the national standard GB / T 2410-2008, with one glass slide as a reference. The thickness of the TPU film samples was 1±0.05 mm. The scanning speed was 600 nm / min, and the scanning range was 200-1000 nm.

[0103] (2) Yellowing index (UV200h): Tested according to the test standard ASTM E313-05.

[0104] (3) Dry heat aging test: Tested according to the test standard GB / T 29848-2018.

[0105] (4) Tensile strength test: Tested according to the test standard ASTM D-882.

[0106] Table 1

[0107]

Claims

1. A photovoltaic encapsulation material, characterized in that, By weight, its raw materials include: 20-50 parts of oligomeric diol, 1-5 parts of curing agent, 0-2 parts of chain extender, 0-2 parts of catalyst, 10-40 parts of organic solvent, 0.05-1 part of leveling agent, and 0.1-1 part of defoamer; The oligomeric diol is a polyester diol and / or a polyether diol; The oligomeric diol is a polyester diol and a polyether diol, with a weight ratio of 1:(2-5). The molecular weight of the polyester diol is 2000-4000 g / mol, and the molecular weight of the polyether diol is 1000-3000 g / mol. The curing agent is a mixture of IPDI trimer and HDI trimer, with a mass ratio of (2-5):1; The chain extender is a fluorinated chain extender and a small molecule diol; The mass ratio between the fluorinated chain extender and the small molecule diol is (1-3):(3-6); The fluorinated chain extender is 4,4'-(hexafluoroisopropylidene)diphenol, and the small molecule diol is 1,4-butanediol; The method for preparing the photovoltaic encapsulation material includes the following steps: S1: Preparation of TPU film; The curing agent, oligomeric diol, and catalyst are added to the reaction apparatus and stirred. Then, the solvent is added to stabilize the molar ratio of NCO / OH in the system. After that, the chain extender, defoamer, and leveling agent are added, stirred, and then dried to form a TPU film. In step S1, the molar ratio of NCO / OH is (1.4-1.8):

1.

2. A method for preparing a photovoltaic encapsulation material according to claim 1, characterized in that, The steps include the following: S1: Preparation of TPU film; The curing agent, oligomeric diol, and catalyst are added to the reaction apparatus and stirred. Then, the solvent is added to stabilize the molar ratio of NCO / OH in the system. After that, the chain extender, defoamer, and leveling agent are added and stirred, and then dried to form a TPU film.

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