A packaging adhesive for photovoltaic 0BB technology and a preparation method thereof

Abstract

The application discloses a photovoltaic 0BB technology encapsulating glue prepared from the following raw materials in percentage by weight: bio-based polyurethane modified acrylate resin 30-70 parts, modified flexible acrylate monomer 10-30 parts, yellowing-resistant acrylate monomer 10-30 parts, photoinitiator 1-7 parts and acrylate modified antioxidant 0.5-4 parts. The photovoltaic 0BB technology encapsulating glue prepared by the application is a bio-based UV curing glue, has better yellowing resistance, low curing energy, low high-temperature volatile matter and good high-low temperature impact performance.

Description

Technical Field

[0001] This invention belongs to the field of photocurable materials and relates to an encapsulating adhesive for photovoltaic OBB technology and its preparation method, which is applicable to the photovoltaic encapsulation field. Background Technology

[0002] Currently, under the overarching goal of energy conservation and cost reduction, photovoltaic (PV) companies are facing competition from traditional TOPCon and HJT (heterojunction) cell technologies. While the mass production cost of traditional HJT cells is high compared to TOPCon, their industrialization must be accelerated. Therefore, developing OBB (Optical Bypass) technology and solving its technical challenges has become a key area of ​​competition for PV companies. The advantages of OBB include: 1) reduced silver loss; 2) enhanced conductivity; and 3) lower-temperature encapsulation processes that allow for thinner silicon wafers. OBB technology can save 2 cents / W for TOPCon and 4 cents / W for HJT, with TOPCon being more sensitive to the maturity of the OBB process.

[0003] UV-curable materials have been widely studied and rapidly adopted across various industries due to their numerous advantages, including fast curing speed, environmental friendliness, low energy consumption, and solvent-free evaporation. However, UV-curable adhesives also have their limitations. Conventional UV-curable adhesives have significant limitations in applications requiring resistance to yellowing and small molecule migration. In OBB encapsulation applications, the adhesive needs to have excellent high-temperature yellowing resistance and low small molecule volatile content. The UV-curable encapsulating adhesive of this invention can solve the problems of conventional technologies.

[0004] Furthermore, against the backdrop of the national goals of carbon peaking and carbon neutrality, controlling carbon emissions has become imperative. Consequently, various green and low-carbon materials have frequently appeared in the public eye in recent years, especially for the manufacturing industry, where new materials and green energy are essential for sustainable development. In this process, biodegradable materials, represented by bio-based materials, have attracted widespread attention from numerous companies due to their excellent environmental characteristics and application capabilities. The UV-curable encapsulating adhesive of this invention is designed and synthesized based on bio-based raw materials, possessing a high bio-based content and meeting the demands of green and low-carbon development. Summary of the Invention

[0005] To address the shortcomings of existing UV adhesives in terms of high-temperature yellowing and small molecule migration, this invention provides an encapsulating adhesive for photovoltaic OBB technology and its preparation method, which can meet the requirements of high-reliability photovoltaic applications.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0007] An encapsulating adhesive for photovoltaic OBB technology is composed of the following raw materials by weight percentage: 30-70 parts of bio-based polyurethane modified acrylate resin, 10-30 parts of modified flexible acrylate monomer, 10-30 parts of yellowing resistant acrylate monomer, 1-7 parts of photoinitiator, and 0.5-4 parts of acrylate modified antioxidant.

[0008] Based on the above technical solution, the present invention can be further improved as follows.

[0009] Furthermore, the aforementioned bio-based polyurethane acrylate resin refers to a bio-based polyurethane acrylate resin synthesized using bio-based propylene glycol, 1,5-pentanediisocyanate, and lactic acid hydroxy acrylate. The bio-based propylene glycol refers to a bio-based polyol produced from plant-derived propylene glycol. The 1,5-pentanediisocyanate (PDI) is a novel aliphatic diisocyanate, typically synthesized from bio-based 1,5-pentanediamine (PDA) via phosgenation. The lactic acid hydroxy acrylate is a novel bio-based specialty acrylate, using corn or non-grain renewable resources as raw materials, and possesses low-carbon and environmentally friendly characteristics.

[0010] The synthesis method of bio-based polyurethane acrylate resin is as follows: First, add 1 mole of bio-based propylene glycol, 2 moles of 1,5-pentanediisocyanate, and 20 ppm of dibutyltin dilaurate catalyst to a three-necked flask equipped with a thermometer. Control the temperature at 70-75 degrees Celsius and react for 2 hours. Then, add 2 moles of lactic acid hydroxy acrylate end-capping agent and 500 ppm of p-hydroxyanisole polymerization inhibitor. React at 70-75 degrees Celsius for 2-3 hours. Analyze the content of NCO groups using an infrared spectrometer. Stop the heating reaction when the NCO peak completely disappears to obtain bio-based polyurethane acrylate resin.

[0011] Reaction equation:

[0012]

[0013] Furthermore, the modified flexible acrylate monomer refers to the product of the reaction of acrylic acid and an epoxy silane coupling agent, and the epoxy silane coupling agent refers to [8-(epoxypropyloxy)-n-octyl]trimethoxysilane (CAS: 1239602-38-0).

[0014] The method for synthesizing the modified flexible acrylate monomer is to first add 1 mole of acrylic acid, 1 mole of [8-(epoxypropyloxy)-n-octyl]trimethoxysilane, triphenylphosphine catalyst (50 ppm), and p-hydroxyanisole (500 ppm) into a three-necked flask equipped with a thermometer, control the temperature at 100-120 degrees Celsius, and react for 4 hours. After the reaction is completed, stop heating to obtain the modified flexible acrylate monomer.

[0015] The reaction equation is as follows:

[0016]

[0017] Furthermore, the yellowing-resistant acrylate monomer refers to one or a mixture of any of the following: 4-tert-butylcyclohexyl acrylate, tetrahydrofuran acrylate (THFA), lauryl acrylate (LA), hydroxyethyl acrylate (HEA), isobornyl acrylate (IBOA), 1,6-hexanediol diacrylate (HDDA), and pentaerythritol triacrylate (PETA).

[0018] Furthermore, the photoinitiator is one or a mixture of several of the following: 1173 (2-hydroxy-2-methyl-1-phenylpropanone), 184 (1-hydroxycyclohexylbenzophenone), 819 (bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide), and TPO (2,4,6-trimethylbenzoyl diphenylphosphine oxide).

[0019] Furthermore, the acrylate-modified antioxidant refers to the product of the reaction between ethyl isocyanate and antioxidant 565 (CAS: 991-84-4).

[0020] The method for synthesizing acrylate-modified antioxidants is to first add 1 mole of ethyl isocyanate and 1 mole of antioxidant 565 to a three-necked flask equipped with a thermometer, control the temperature at 30-50 degrees Celsius, and react for 2 hours. After the reaction is complete, the acrylate-modified antioxidant can be obtained.

[0021] The reaction equation is as follows:

[0022]

[0023] The preparation method of the encapsulating adhesive for photovoltaic OBB technology according to the present invention includes: weighing 30-70 parts of bio-based polyurethane modified acrylate resin, 10-30 parts of modified flexible acrylate monomer, 10-30 parts of yellowing resistant acrylate monomer, 1-7 parts of photoinitiator, and 0.5-4 parts of acrylate modified antioxidant, and adding them sequentially into a mixer, evacuating to a vacuum degree of -0.08 to -0.05 MPa, stirring at 500-1000 rpm for 0.5-2 hours, stirring until uniform, allowing to air dry to room temperature, and then sealing and packaging.

[0024] The beneficial effects of this invention are as follows: The photovoltaic OBB encapsulant prepared by this invention uses bio-based raw materials to design and synthesize a novel polymer resin structure. Bio-based sources are simple and readily available, meeting the requirements of green and low-carbon development. This resin structure also exhibits better heat resistance to yellowing, resistance to high and low temperature impacts, and higher elongation. A special epoxide-modified acrylate monomer was also synthesized. The carbon-carbon double bonds in the epoxide acrylate structure have higher reactivity, resulting in an encapsulant with lower UV curing energy. Furthermore, the silane coupling agent in the molecular structure enables the encapsulant to maintain excellent adhesion even under harsh high-temperature and high-humidity environments. In addition, an antioxidant with acrylate functional groups was synthesized. This type of antioxidant can participate in the UV curing reaction, giving the formulation excellent heat resistance to yellowing, low small molecule migration, and excellent performance even under rigorous reliability testing. Detailed Implementation

[0025] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0026] Synthesis Example 1

[0027] The synthesis method of bio-based polyurethane acrylate resin is as follows: First, add 1 mole of bio-based propylene glycol, 2 moles of 1,5-pentanediisocyanate, and the catalyst dibutyltin dilaurate (20 ppm) to a three-necked flask equipped with a thermometer. Control the temperature at 75 degrees Celsius and react for 2 hours. Then, add 2 moles of lactic acid hydroxy ester as a capping agent and p-hydroxyanisole (500 ppm) as a polymerization inhibitor. React at 75 degrees Celsius for 3 hours. Analyze the content of NCO groups using an infrared spectrometer. Stop the heating reaction when the NCO peak completely disappears to obtain the bio-based polyurethane acrylate resin.

[0028] Synthesis Example 2

[0029] The method for synthesizing the modified flexible acrylate monomer is to first add 1 mole of acrylic acid, 1 mole of [8-(epoxypropyloxy)-n-octyl]trimethoxysilane, triphenylphosphine catalyst (50 ppm), and p-hydroxyanisole (500 ppm) into a three-necked flask equipped with a thermometer, control the temperature at 110 degrees Celsius, and react for 4 hours. After the reaction is completed, stop heating to obtain the modified flexible acrylate monomer.

[0030] Synthesis Example 3

[0031] The method for synthesizing acrylate-modified antioxidants is to first add 1 mole of ethyl isocyanate and 1 mole of antioxidant 565 to a three-necked flask equipped with a thermometer, control the temperature at 40 degrees Celsius, and react for 2 hours. After the reaction is complete, acrylate-modified antioxidants can be obtained.

[0032] Example 1

[0033] Accurately weigh the following raw materials: 50g of bio-based polyurethane acrylate resin; 15g of modified flexible acrylate monomer; 15g of IBOA; 3g of photoinitiator 184; 1g of photoinitiator TPO; and 2g of acrylate-modified antioxidant. Add the above components sequentially to a dual planetary mixer, evacuate to a vacuum degree of -0.08MPa, and stir at 500 rpm for 2 hours until homogeneous. Allow to air dry to room temperature to obtain the encapsulating adhesive for photovoltaic OBB technology, and then seal and package it.

[0034] Example 2

[0035] Accurately weigh the following raw materials: 40g of bio-based polyurethane acrylate resin; 30g of modified flexible acrylate monomer; 18g of THFA; 1g of photoinitiator 184; 1g of photoinitiator 1173; and 1g of acrylate-modified antioxidant. Add the above components sequentially to a dual planetary mixer, evacuate to a vacuum degree of -0.05MPa, and stir at 750 rpm for 1 hour until homogeneous. Allow to air dry to room temperature to obtain the encapsulating adhesive for photovoltaic OBB technology, and then seal and package it.

[0036] Example 3

[0037] Accurately weigh the following raw materials: bio-based polyurethane acrylate resin, 69g; modified flexible acrylate monomer, 11g; HEA, 10g; photoinitiator 1173: 3g; photoinitiator 819: 2g; acrylate-modified antioxidant, 0.5g. Add the above components sequentially to a dual planetary mixer, evacuate to a vacuum degree of -0.06MPa, stir at 700 rpm for 1.5 hours until homogeneous, and allow to air dry to room temperature to obtain the encapsulating adhesive for photovoltaic OBB technology. Seal and package.

[0038] Example 4

[0039] Accurately weigh the following raw materials: bio-based polyurethane acrylate resin, 32g; modified flexible acrylate monomer, 30g; I BOA, 25g; LA, 5g; photoinitiator 184, 3g; photoinitiator TPO, 1g; acrylate-modified antioxidant, 4g. Add the above components sequentially to a dual planetary mixer, evacuate to a vacuum degree of -0.07MPa, stir at 800 rpm for 1 hour until homogeneous, and allow to air dry to room temperature to obtain the encapsulating adhesive for photovoltaic OBB technology. Seal and package.

[0040] Example 5

[0041] Accurately weigh the following raw materials: bio-based polyurethane acrylate resin, 49g; modified flexible acrylate monomer, 25g; IBOA, 6g; HEA, 5g; photoinitiator 1173, 3g; photoinitiator TPO, 4g; acrylate-modified antioxidant, 3g. Add the above components sequentially to a dual planetary mixer, evacuate to a vacuum degree of -0.08MPa, stir at 1000 rpm for 0.5 hours until homogeneous, and allow to air dry to room temperature to obtain the encapsulating adhesive for photovoltaic OBB technology. Seal and package.

[0042] Comparative Example 1

[0043] Accurately weigh the following raw materials: PTMG type polyurethane modified acrylate resin (Changxing Chemical U282), 30g; IBOA, 60g; HEA, 10g; photoinitiator 184, 3g; photoinitiator TPO, 1g; add the above components sequentially into a double planetary mixer, evacuate to a vacuum degree of -0.08MPa, stir at 500 rpm for 2 hours until uniform, allow to air dry to room temperature to obtain UV-curable adhesive, and seal and package.

[0044] Comparative Example 2

[0045] Accurately weigh the following raw materials: polyester-type polyurethane modified acrylate resin (Changxing Chemical U384), 35g; THFA, 41g; I BOA, 15g; photoinitiator 1173, 3g; photoinitiator TPO, 1g; add the above components sequentially into a dual planetary mixer, evacuate to a vacuum degree of -0.05MPa, stir at 750 rpm for 1 hour until uniform, allow to air dry to room temperature to obtain UV-curable adhesive, and seal and package.

[0046] The performance of a photovoltaic OBB technology encapsulant of the present invention was tested through the following experiments.

[0047] Table 1. Comparison of test results between samples prepared in Examples 1-5 and ordinary UV-curable adhesives.

[0048]

[0049]

[0050] As can be seen from the above results, the photovoltaic OBB encapsulating adhesive of the present invention has better resistance to yellowing, lower curing energy, and lower volatilization at high temperatures compared with existing ordinary UV curing adhesives.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An encapsulating adhesive for photovoltaic OBB technology, comprising the following raw materials by weight percentage: 30-70 parts of bio-based polyurethane modified acrylate resin, 10-30 parts of modified flexible acrylate monomer, 10-30 parts of yellowing resistant acrylate monomer, 1-7 parts of photoinitiator, and 0.5-4 parts of acrylate modified antioxidant. The method for synthesizing the bio-based polyurethane acrylate resin is as follows: First, add 1 mole of bio-based propylene glycol, 2 moles of 1,5-pentanediisocyanate, and 20 ppm of dibutyltin dilaurate to a three-necked flask equipped with a thermometer, control the temperature at 70-75 degrees Celsius, and react for 2 hours. Then, add 2 moles of lactic acid hydroxy acrylate as a capping agent and 500 ppm of p-hydroxyanisole as a polymerization inhibitor, and react at 70-75 degrees Celsius for 2-3 hours. Analyze the content of NCO groups using an infrared spectrometer. When the NCO peak completely disappears, stop the heating reaction to obtain the bio-based polyurethane acrylate resin. Reaction equation: ； The modified flexible acrylate monomer is a product of the reaction between acrylic acid and an epoxy silane coupling agent, wherein the epoxy silane coupling agent is [8-(epoxypropyloxy)-n-octyl]trimethoxysilane (CAS: 1239602-38-0).

2. The encapsulating adhesive for photovoltaic OBB technology according to claim 1, characterized in that, The method for synthesizing the modified flexible acrylate monomer is as follows: 1 mole of acrylic acid, 1 mole of [8-(epoxypropyloxy)-n-octyl]trimethoxysilane, 50 ppm of triphenylphosphine, and 500 ppm of p-hydroxyanisole are added to a three-necked flask equipped with a thermometer. The temperature is controlled at 100-120 degrees Celsius and the reaction is carried out for 4 hours. After the reaction is completed, the heating reaction is stopped to obtain the modified flexible acrylate monomer. The reaction equation is as follows: 。 3. The encapsulating adhesive for photovoltaic OBB technology according to claim 1, characterized in that, The yellowing-resistant acrylate monomer is one or a mixture of several of the following: 4-tert-butylcyclohexyl acrylate, tetrahydrofuran acrylate, lauryl acrylate, hydroxyethyl acrylate, isobornyl acrylate, 1,6-hexanediol diacrylate, and pentaerythritol triacrylate; the photoinitiator is one or a mixture of several of the following: 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexylbenzophenone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2,4,6-trimethylbenzoyl diphenylphosphine oxide.

4. The encapsulating adhesive for photovoltaic OBB technology according to claim 1, characterized in that, The acrylate-modified antioxidant refers to the product of the reaction between ethyl isocyanate and antioxidant 565 (CAS: 991-84-4). The synthesis method of the acrylate-modified antioxidant is to first add 1 mole of ethyl isocyanate and 1 mole of antioxidant 565 to a three-necked flask equipped with a thermometer, control the temperature at 30-50 degrees, and react for 2 hours. After the reaction is completed, the acrylate-modified antioxidant can be obtained. The reaction equation is as follows: 。 5. A method for preparing an encapsulating adhesive for photovoltaic OBB technology according to claim 1, comprising: Weigh out 30-70 parts of bio-based polyurethane modified acrylate resin, 10-30 parts of modified flexible acrylate monomer, 10-30 parts of yellowing-resistant acrylate monomer, 1-7 parts of photoinitiator, and 0.5-4 parts of acrylate modified antioxidant. Add these to a mixer in sequence, evacuate to a vacuum degree of -0.08 to -0.05 MPa, and stir at 500-1000 rpm for 0.5-2 hours until homogeneous. Allow to air dry to room temperature, then seal and package.

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