Thermosetting epoxy adhesive for photovoltaic 0BB technology and application of thermosetting epoxy adhesive

Abstract

The invention discloses a thermosetting epoxy adhesive for a photovoltaic 0BB technology. The thermosetting epoxy adhesive comprises the following components in parts by mass: 10-20 parts of castor oil structure oxetane, 30-70 parts of alicyclic epoxy, 1-10 parts of polyester polyol, 1-5 parts of hydrogenated rosin resin, 0.6-3 parts of a thermal initiator, 0.5-1.5 parts of a coupling agent, 0.2-1.0 part of an anti-aging agent and 1-7 parts of a thixotropic agent. The thermosetting epoxy glue for the photovoltaic 0BB technology has the advantages of good yellowing resistance, low volatile matter at high temperature and good high and low temperature impact performance.

Description

Technical Field

[0001] The invention relates to the field of solar photovoltaic technology, and is applicable to packaging glue for photovoltaic 0BB technology and a preparation method thereof. Background Art

[0002] Traditional PERC, new TOPcon cells and HJT (heterojunction) cells, especially HJT cells, require a high amount of silver paste. Under the premise of energy conservation and cost reduction for photovoltaic companies, reducing the use of silver paste has become one of the important ways to reduce costs.

[0003] Busbar-free modules, also known as 0BB technology, are an innovative photovoltaic cell module technology that eliminates the busbar of traditional cells and uses welding strips to derive current in the module link. Specifically, busbar-free cells use welding strips to collect fine grid current and interconnect cells. The width of the welding strip is smaller than the width of the traditional busbar. In addition, busbar-free cells usually use copper welding strips, and the original silver electrode busbar is completely replaced, realizing the function of base metal replacing the traditional silver busbar. The benefits of 0BB are: 1) reduce silver consumption; 2) enhance conductivity; 3) low-temperature packaging process can carry thinner silicon wafers.

[0004] At present, the main bonding materials for 0BB solder strips include UV glue, heat-curing epoxy glue, heat-curing organic silicone glue, and light-curing materials. They have been widely studied and rapidly promoted in various industries due to their many outstanding advantages such as fast curing speed, environmental friendliness, low energy consumption, and no solvent volatilization. However, UV light-curing glue also has its own limitations. Conventional UV light-curing glue has obvious limitations in the application scenarios of yellowing resistance and small molecule migration, and UV curing has certain damage to the battery cell; the bonding strength of organic silicone to the solder strip is low; epoxy glue has high adhesion to the welding wire, but epoxy glue has great brittleness and yellowing. In 0BB packaging applications, the glue needs to have excellent high-temperature yellowing resistance and low small molecule volatiles. The thermosetting packaging glue of the present invention can solve the problems of conventional technologies. Summary of the invention

[0005] In order to solve the problem of the brittleness and yellowing of heat-cured epoxy adhesive in the prior art, the present invention provides a packaging adhesive for photovoltaic 0BB technology and a preparation method thereof, which can meet the requirements of high-reliability photovoltaic applications. The technical solution of the present invention to solve the above technical problems is as follows: A thermosetting epoxy adhesive for bonding welding wires of a main grid-free component comprises the following components by mass fraction: 10-20 parts of castor oil structured oxabutane, 30-70 parts of alicyclic epoxy, 1-10 parts of polyester polyol, 1-5 parts of hydrogenated rosin resin, 0.6-3 parts of thermal initiator, 0.5-1.5 parts of coupling agent, 0.2-1.0 parts of anti-aging agent and 1-7 parts of thixotropic agent.

[0006] The castor oil structured oxacyclobutane is prepared by a substitution reaction between castor oil and 3-ethyl-3-bromomethyloxacyclobutane under the catalysis of potassium hydroxide to synthesize a trifunctional derivative, which is added as a diluent into a cationic epoxy polymerization system to improve the hydrophobicity of the material, reduce the brittleness of the epoxy, and maintain its heat resistance.

[0007] The method for synthesizing castor oil structured oxabutane is as follows: first, 0.1 mol of castor oil is placed in a three-necked flask equipped with a reflux condenser and a thermometer, then 0.3 mol of 3-bromomethyl-3-ethyl-oxacyclobutane, 30 ml of toluene and 0.2 mol of potassium hydroxide are added, the temperature is raised to 100°C, the speed is set to 500 r / min, the reaction is carried out for 10 hours, and the reaction is terminated. The reaction solution is washed with distilled water for 3 times, and the solvent is removed by vacuum distillation to obtain the product, and the chemical reaction formula is as follows: .

[0008] The alicyclic epoxy resin is one of 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexyl methyl ester, bis((3,4-epoxycyclohexyl)methyl)adipate, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexylcarboxylate and a polymerization product of caprolactone (1:1) or a mixture of two or more thereof.

[0009] The polyester polyols are mainly polycaprolactone polyols, polycarbonate polyols, caprolactone-modified (meth)acrylates and other ester polyols, especially ternary polycaprolactone polyols, which have better effects. The structure is as follows: .

[0010] The hydrogenated rosin resin is required to have a melting point of 85-130 degrees Celsius, such as one of Arakawa KE-604, KE-100, and KE-311.

[0011] The thixotropic agent can be hydrophobic silica powder or hydrophilic silica. In this experiment, hydrophilic silica is selected, such as one of Wacker's T40, Evonik A300, A380, etc.

[0012] The thermal initiator is an amine-blocked hexafluoroantimonate with a fast curing speed.

[0013] The coupling agent is selected from 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane or 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane.

[0014] The anti-aging agent should be resistant to both heat aging and light aging. The heat antioxidants include 1076, 1035, 1010, BHT, etc., and the light antioxidants include UV326, UV328, UV123, etc. The present invention selects a compound antioxidant, i.e., a compound of a heat antioxidant and a light antioxidant, with a compounding ratio of 4-8:1-4.

[0015] The invention discloses a thermosetting epoxy adhesive for bonding welding wires of a main grid-free assembly, comprising: weighing 10-20 parts of castor oil structured oxabutane, 30-70 parts of alicyclic epoxy, 1-10 parts of polyester polyol, 1-5 parts of hydrogenated rosin resin, 0.6-3 parts of thermal initiator, 0.5-1.5 parts of coupling agent, 0.2-1.0 parts of anti-aging agent, and 1-7 parts of thixotropic agent, adding the mixture into a blender in sequence, stirring for 30 minutes, and then evacuating the mixture to a vacuum degree of -0.08 to -0.05 MPa, stirring at 1000 to 1500 rpm for 0.5 to 2 hours, stirring evenly, letting the mixture stand naturally to room temperature, and sealing and packaging.

[0016] The beneficial effects of the present invention are as follows: the thermosetting epoxy adhesive for welding wire bonding of main grid-free components described in the present invention adopts castor oil structural unit design to synthesize a new castor oil oxybutane, whose structural characteristics determine that it has good water resistance and flexibility, can effectively solve the brittle shortcomings of epoxy resin, and ensure the strength of epoxy; alicyclic epoxy resin can ensure rapid curing and heat resistance, as well as strength; the addition of polyester polyol and hydrogenated rosin can effectively bond the resin to the welding strip; the addition of thixotropic agent must ensure that there is a certain glue height after printing to achieve the effect of coating the welding wire, especially to ensure its light transmittance and printing process characteristics. This experimental design does not have the addition of small molecules to ensure that there is no migration of small molecules, and the welding wire adhesive is exposed to light and heat conditions, so the introduction of a composite anti-aging agent can effectively ensure that the photovoltaic adhesive will not yellow after aging for 1500 hours. DETAILED DESCRIPTION

[0017] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0018] Example 1 Weigh 15 parts of castor oil structure oxabutane, 65 parts of 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexyl methyl ester, 5 parts of ternary polycaprolactone polyol with a molecular weight of 2000, 5 parts of Arakawa KE604 hydrogenated rosin resin, 0.8 parts of thermal initiator amine blocked hexafluoroantimonate, 1 part of coupling agent A1861, 0.5 parts of aging agent 1076: UV326 = 2:1, and 6 parts of thixotropic agent T40; add them into a blender in sequence, stir for 30 minutes, then evacuate to a vacuum degree of -0.08 to -0.05 MPa, stir at 1000 to 1500 rpm for 0.5 to 2 hours, stir evenly, let it dry naturally to room temperature, and seal and package.

[0019] Example 2 Weigh 10 parts of castor oil structure oxabutane, 70 parts of bis((3,4-epoxycyclohexyl)methyl) adipate, 10 parts of ternary polycaprolactone polyol with a molecular weight of 2000, 5 parts of Arakawa KE100 hydrogenated rosin resin, 0.8 parts of thermal initiator, 1 part of coupling agent, 0.5 parts of anti-aging agent 1076: UV326 = 2:1, and 6 parts of thixotropic agent T40; add them into a blender in sequence, stir for 30 minutes, then evacuate to a vacuum degree of -0.08 to -0.05 MPa, stir at 1000 to 1500 rpm for 0.5 to 2 hours, stir evenly, let it dry naturally to room temperature, and seal it for packaging.

[0020] Example 3 Weigh 10 parts of castor oil structure oxabutane, 70 parts of 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexyl methyl ester, 10 parts of ternary polycaprolactone polyol with a molecular weight of 500, 5 parts of Arakawa 604 hydrogenated rosin resin, 0.8 parts of thermal initiator, 1 part of coupling agent, 0.5 parts of anti-aging agent 1076: UV326 = 2:1, and 6 parts of thixotropic agent A300; add them into a blender in sequence, stir for 30 minutes, then evacuate to a vacuum degree of -0.08 to -0.05 MPa, stir at 1000 to 1500 rpm for 0.5 to 2 hours, stir evenly, let it dry naturally to room temperature, and seal it for packaging.

[0021] Comparative Example 1 Weigh 15 parts of hydroxymethyl butane, 65 parts of 3,4-epoxycyclohexyl carboxylic acid-3',4'-epoxycyclohexyl methyl ester, 5 parts of ternary polycaprolactone polyol with a molecular weight of 2000, 5 parts of Arakawa 604 hydrogenated rosin resin, 0.8 parts of thermal initiator amine blocked hexafluoroantimonate, 1 part of coupling agent A1861, 0.5 parts of anti-aging agent 1076: UV326 = 2:1, and 6 parts of thixotropic agent 300; add them into a blender in sequence, stir for 30 minutes, then evacuate to a vacuum degree of -0.08 to -0.05 MPa, stir at 1000 to 1500 rpm for 0.5 to 2 hours, stir evenly, let it dry naturally to room temperature, and seal and package.

[0022] Comparative Example 2 Weigh 10 parts of castor oil structure oxabutane, 70 parts of bis((3,4-epoxycyclohexyl)methyl) adipate, 10 parts of dibasic polycaprolactone polyol with a molecular weight of 2000, 5 parts of hydrogenated rosin resin, 0.8 parts of thermal initiator, 1 part of coupling agent, 0.5 parts of anti-aging agent 1076: UV326 = 2:1, and 6 parts of thixotropic agent T40; add them into a blender in sequence, stir for 30 minutes, then evacuate to a vacuum degree of -0.08 to -0.05 MPa, stir at 1000 to 1500 rpm for 0.5 to 2 hours, stir evenly, let it dry naturally to room temperature, and seal it for packaging.

[0023] Comparative Example 3 Weigh 10 parts of castor oil structure oxabutane, 70 parts of 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexyl methyl ester, 10 parts of ternary polycaprolactone polyol with a molecular weight of 500, 5 parts of Arakawa 604 hydrogenated rosin resin, 0.8 parts of thermal initiator, 1 part of coupling agent, 0.5 parts of anti-aging agent 1076: UV326 = 2:1, and 6 parts of Evonik thixotropic agent R974; add them into a blender in sequence, stir for 30 minutes, then evacuate to a vacuum degree of -0.08 to -0.05 MPa, stir at 1000 to 1500 rpm for 0.5 to 2 hours, stir evenly, let it dry naturally to room temperature, and seal it for packaging.

[0024] Comparative Example 4

[0025] Weigh 15 parts of castor oil structure oxabutane, 65 parts of 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexyl methyl ester, 5 parts of ternary polycaprolactone polyol with a molecular weight of 2000, 5 parts of Arakawa KE604 hydrogenated rosin resin, 0.8 parts of thermal initiator amine blocked hexafluoroantimonate, 1 part of coupling agent A1861, and 6 parts of thixotropic agent T40; add them into a blender in sequence, stir for 30 minutes, then evacuate to a vacuum degree of -0.08 to -0.05 MPa, stir at 1000 to 1500 rpm for 0.5 to 2 hours, stir evenly, let it stand naturally to room temperature, and seal and package.

[0026] The performance of the encapsulation adhesive for photovoltaic 0BB technology of the present invention was tested by the following experiment.

[0027] Table 1 Comparative test results of curing adhesives in the examples and comparative examples Table 1 Performance index table

[0028] It can be seen from the above results that the welding wire adhesive for photovoltaic 0BB components of the present invention has the characteristics of good adhesion to welding tape, small molecule volatility, low water absorption, no yellowing at high temperature, good printability, etc., which meets the welding tape bonding performance requirements of photovoltaic component 0BB technology.

[0029] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A thermosetting epoxy adhesive for photovoltaic 0BB technology, comprising the following mass fractions: 10-20 parts of castor oil structure oxabutane, 30-70 parts of alicyclic epoxy, 1-10 parts of polyester polyol, 1-5 parts of hydrogenated rosin resin, 0.6-3 parts of thermal initiator, 0.5-1.5 parts of coupling agent, 0.2-1.0 parts of anti-aging agent, and 1-7 parts of thixotropic agent.

2. The thermosetting epoxy adhesive for photovoltaic OBB technology according to claim 1, characterized in that: The castor oil structured oxacyclobutane is a trifunctional derivative synthesized by a substitution reaction between castor oil and 3-ethyl-3-bromomethyloxacyclobutane under the catalysis of potassium hydroxide; its chemical reaction formula is as follows: 。 3. A thermosetting epoxy adhesive for photovoltaic OBB technology according to claim 1, characterized in that: The alicyclic epoxy resin is one or more of 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexyl methyl ester, bis((3,4-epoxycyclohexyl)methyl)adipate, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexylcarboxylate and caprolactone in a 1:1 ratio.

4. A thermosetting epoxy adhesive for photovoltaic OBB technology according to claim 1, characterized in that: The polyester polyol is a ternary polycaprolactone polyol.

5. A thermosetting epoxy adhesive for photovoltaic OBB technology according to claim 1, characterized in that: The hydrogenated rosin resin is one of Arakawa KE-604, KE-100 and KE-311.

6. A thermosetting epoxy adhesive for photovoltaic OBB technology according to claim 1, characterized in that: The thixotropic agent is one of Wacker's T40, Evonik's A300 and A380; the thermal initiator is amine-blocked hexafluoroantimonate.

7. A thermosetting epoxy adhesive for photovoltaic OBB technology according to claim 1, characterized in that: The coupling agent is one of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane.

8. A thermosetting epoxy adhesive for photovoltaic OBB technology according to claim 1, characterized in that: The anti-aging agent is a heat antioxidant and a light antioxidant in a compounding ratio of 4-8:1-4.

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