Organic silicon thermosetting adhesive for photovoltaic N-type battery 0BB assembly and preparation method of organic silicon thermosetting adhesive

Abstract

The invention relates to the technical field of adhesives for photovoltaic cells, in particular to an organic silicon thermosetting adhesive for a photovoltaic N-type cell 0BB assembly and a preparation method of the organic silicon thermosetting adhesive. The inventor adds the anti-poisoning agent, adjusts the ratio of the inhibitor to the catalyst, and adjusts the properties of the thermosetting adhesive in all orientations by compounding the low-hydrogen-content silicone oil and the high-hydrogen-content silicone oil. Finally, the thermosetting adhesive obtained according to the formula provided by the invention can simultaneously meet the requirements that the adhesive point tension is greater than or equal to 0.3 N, the light transmittance is greater than 90%, the TC90 is less than or equal to 15s, the thixotropy is greater than 5 and the operable time is greater than or equal to 8h, and is far higher than the general standard.

Description

Technical Field

[0001] This invention relates to the field of adhesives for photovoltaic cells, specifically to an organosilicon thermosetting adhesive for photovoltaic N-type cell OBB modules and its preparation method. Background Technology

[0002] N-type OBB modules eliminate the main grid, retaining only the fine grid, resulting in a 30-50% reduction in silver paste usage. This reduction in silver usage lowers the cost of N-type cells, leading to the widespread adoption of N-type OBB technology. However, due to the unique structure of the N-type cells obtained through OBB modules, the fine grid directly carries the functions of current collection and welding. This necessitates high-precision bonding of the solder ribbon to the fine grid, increasing the complexity of the welding process. Thermosetting adhesive becomes a crucial element in securing the solder ribbon.

[0003] The specific processes in the entire OBB module manufacturing process are as follows: 1) Printing thermosetting adhesive onto preheated solar cells for pre-curing; 2) Precisely placing the flux-coated solder ribbon onto the grid; 3) The entire solar cell enters the light box for paste alloying and complete curing of the thermosetting adhesive. During the OBB module manufacturing process, the flux and thermosetting adhesive are in direct contact. However, the flux contains components such as tin rosinate, which contains heavy metals Sn and Pb. When the flux and thermosetting adhesive come into contact, Sn... 2+ / Pb 2+ Occupying platinum empty orbitals to form stable complexes causes partial catalyst failure, resulting in incomplete curing and thus reducing the pull force of the adhesive dots.

[0004] Currently, various strategies have emerged to address platinum catalyst poisoning. For example, CN104403626B discloses a highly poison-resistant single-component potting compound for LED driver power supplies and its preparation method. This method adjusts the ratio of inhibitor to platinum catalyst to obtain a specific potting compound, resulting in an excess of platinum catalyst to address the poisoning problem. However, the reason for catalyst poisoning in LED driver power supplies is that rosin, flux residues, and acrylic insulating tape on the highly integrated circuit board inside the LED driver power supply can deactivate the platinum complex catalyst in the potting compound, leading to slower or even no curing. Firstly, the flux and potting compound do not directly contact each other, and the residual heavy metal content in flux residues is low, while the heavy metal content in OBB modules is high, increasing the difficulty of solving the poisoning problem. Secondly, LED driver power supplies do not have strict requirements for curing time, while photovoltaic cell processes require rapid curing to adapt to production line efficiency.

[0005] Therefore, anti-poisoning strategies for platinum catalysts in different fields need to be adjusted to adapt to different practical needs. In 0BB modules, the difficulty increases significantly because the flux and thermosetting adhesive are in direct contact, and it is still necessary to ensure the excellent curing rate and a certain working time of the thermosetting adhesive. Summary of the Invention

[0006] To address the problem of platinum catalyst poisoning, this invention provides an organosilicon thermosetting adhesive for OBB photovoltaic N-type cells and its preparation method. This organosilicon thermosetting adhesive simultaneously meets the following requirements: adhesive dot tensile strength ≥0.3N, light transmittance >90%, TC90 ≤15s, thixotropy >5, and workability ≥8h, significantly exceeding general standards.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides an organosilicon thermosetting adhesive for photovoltaic N-type cell OBB modules, comprising, by weight: 10-35 parts of vinyl silicone oil 10-20 parts of low-hydrogen silicone oil 5-10 parts of high-hydrogen silicone oil 10-30 parts of vinyl MQ silicone resin Platinum catalyst 0.1-2 parts, Inhibitor 0.1-2 parts, Thixotropic agent 10-30 parts, 1-5 parts of tackifier 5-20 parts diluent 0.1-2 parts of coupling agent, 1-2 parts of anti-poisoning agent.

[0008] The inventors have discovered that in the use of silicone thermosetting adhesives for OBB photovoltaic N-type cells, the platinum catalyst in conventional silicone thermosetting adhesives often reacts with heavy metals in the flux. For example, Sn... 2+ / Pb 2+ Occupying empty platinum orbitals and forming stable complexes causes partial deactivation of the platinum catalyst. This directly affects the dot pull of the silicone thermosetting adhesive, leading to substandard product performance.

[0009] Therefore, the inventors considered adding an anti-poisoning agent to optimize existing silicone thermosetting adhesives. However, simply adding the anti-poisoning agent revealed that while it effectively alleviated the platinum catalyst deactivation problem, it led to a decline in other properties of the thermosetting adhesive. Furthermore, the most critical issues regarding the rapid curing and long workability of silicone thermosetting adhesives used in N-type photovoltaic OBB modules remain unresolved.

[0010] Based on the above, the inventors adjusted the ratio of inhibitor and catalyst, and used a blend of low-hydrogen-content silicone oil and high-hydrogen-content silicone oil to adjust the properties of the thermosetting adhesive in all aspects.

[0011] Ultimately, the thermosetting adhesive obtained according to the formulation provided by this invention can simultaneously meet the following requirements: adhesive dot tensile strength ≥0.3N, light transmittance >90%, TC90 ≤15s, thixotropy >5, and workable time ≥8h, which are far superior to general standards.

[0012] Preferably, the vinyl silicone oil is selected from at least one of end-capped vinyl silicone oil and double-capped vinyl silicone oil; the vinyl content of the vinyl silicone oil is 0.1~0.5wt%.

[0013] Vinyl silicone oils can be composed of vinyl silicone oils with various vinyl contents.

[0014] Preferably, the vinyl content of the vinyl MQ silicone resin is 0.5~1.5wt%.

[0015] Preferably, the mass ratio of the low-hydrogen-content silicone oil to the high-hydrogen-content silicone oil is 3:(1~2).

[0016] Introducing high-hydrogen-content silicone oil, with its high Si-H bond content, can reduce the probability of platinum poisoning and assist anti-poisoning agents in improving the overall anti-poisoning ability of thermosetting adhesives; however, the amount of high-hydrogen-content silicone oil introduced must be moderate.

[0017] Preferably, the hydrogen content of the high-hydrogen silicone oil is 1.5~1.6 wt%; and the hydrogen content of the low-hydrogen silicone oil is 0.2~1.0 wt%.

[0018] High-hydrogen-content silicone oil can be composed of various high-hydrogen-content silicone oils, while low-hydrogen-content silicone oil can be composed of various low-hydrogen-content silicone oils.

[0019] Preferably, the mass ratio of the inhibitor to the platinum catalyst is 1:(3~5).

[0020] Adjusting the ratio between inhibitors and catalysts allows for curing in a short time, resulting in a longer workable period throughout the process. The viscosity of the thermosetting adhesive does not increase rapidly, reducing the operational difficulty of screen printing in the process.

[0021] Preferably, the inhibitor is an alkynyl alcohol inhibitor, and the platinum catalyst is a cassette catalyst.

[0022] Preferably, the anti-poisoning agent is aluminum di-sec-butoxyacetoacetate chelate and / or basic aluminum oxide.

[0023] Preferably, the thixotropic agent is a thermally conductive inorganic filler with a particle size of 30-500 nm, the coupling agent is a silane coupling agent, the diluent is light white oil, and the thickener is allyl glycidyl ether.

[0024] The present invention also provides a method for preparing organosilicon thermosetting adhesive for photovoltaic N-type cell OBB modules, comprising: mixing vinyl silicone oil, vinyl MQ silicone resin and thixotropic agent under heating conditions, cooling and degassing, adding inhibitor, and then adding high-hydrogen silicone oil, low-hydrogen silicone oil, catalyst, tackifier, diluent, coupling agent and anti-poisoning agent in batches, and degassing again to obtain the final product.

[0025] Therefore, the present invention has the following beneficial effects: (1) The present invention adjusts the ratio between the inhibitor and the catalyst to cure in a short time. The working time is relatively long during the entire process. The viscosity of the thermosetting adhesive will not increase in a short time, which can reduce the difficulty of screen printing in the process.

[0026] (2) The present invention introduces an anti-poisoning agent, which will not cause the platinum catalyst to be poisoned due to the presence of heavy metal salts such as tin and lead (not limited to heavy metals in flux) during the entire process, resulting in insufficient curing of thermosetting adhesive and affecting the process; and can also ensure the adhesive dot pull of thermosetting adhesive.

[0027] (3) The present invention utilizes a combination of high-hydrogen-content silicone oil and low-hydrogen-content silicone oil to enhance the overall anti-poisoning ability of thermosetting adhesives, thereby ensuring the excellent performance of thermosetting adhesives in all aspects. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0029] In this section, the raw materials were sourced as follows: fumed silica, 500 nm in particle size, purchased from Shouguang Bangze Chemical Co., Ltd.; light white oil, No. 5 light white oil, purchased from Shandong Qingyuan Petrochemical Co., Ltd.; and cassiterite catalyst, 5000 ppm platinum content, purchased from Heraeus.

[0030]

Example

[0031] Table 1 Raw Material List (parts by weight) Table 2 Raw Material List (parts by weight) Inhibitors catalyst Coupling agent Tackifier thixotropic agents Anti-poisoning agent diluent Example 1 0.1 0.3 0.5 1 20 1 9.1 Example 2 0.1 0.4 0.5 1.5 19 1.2 8.3 Example 3 0.1 0.35 0.75 1.5 18 1.5 7.8 Example 4 0.1 0.4 0.5 1.5 18 1.2 8.3 Comparative Example 1 0.1 0.3 0.5 1 20 1 9.1 Comparative Example 2 0.1 0.3 0.5 1 20 1 9.1 Comparative Example 3 0.1 0.35 0.75 1.5 18 1.5 7.8 Comparative Example 4 0.1 0.35 0.75 1.5 18 1.5 7.8 Comparative Example 5 0.1 0.2 0.5 1 20 1 9.2 Comparative Example 6 0.1 0.6 0.5 1 20 1 8.8 In Table 2, the inhibitor is 1-ethynyl-1-cyclohexanol, the platinum catalyst is a caster catalyst, the coupling agent is 3-(2,3-epoxypropoxy)propyltrimethoxysilane, the thickener is allyl glycidyl ether, the thixotropic agent is fumed silica, the anti-poisoning agent is aluminum di-sec-butoxyacetoacetate chelate, and the diluent is light white oil.

[0032] [Performance Testing] In this section, the data is measured using the following methods: ① Transmittance test method: The transmittance at a specific wavelength (280-700nm) is measured using an ultraviolet spectrophotometer.

[0033] ② Tensile strength / elongation at break test method: Refer to standard GB / T528-2009. Specifically, 1mm cured sheet material is cut into type 2 dumbbell-shaped samples and tested using a universal testing machine with a gauge length of 20mm and a tensile speed of 50mm / min.

[0034] ③ Viscosity (mPa·s) and thixotropic test: Viscometer, viscosity at 25℃ and 30 rpm; thixotropic = 3 rpm / 30 rpm.

[0035] ④ Hardness test (Shore A): Refer to standard GB / T 531.1-2008.

[0036] ⑤ Working time: Stir the thermosetting adhesive back and forth at 25℃, and then test the viscosity change of the adhesive and the time corresponding to the increase in viscosity.

[0037] ⑥ Curing speed test method: The M 3000AU1 rotorless vulcanizer was used to test the vulcanization curve of 3g sample at 140℃@3min, and the data of TC10, TC50 and TC90 were recorded.

[0038] ⑦ Thermosetting adhesive bonding tensile test: using tin-lead solder ribbon with a diameter of 0.26mm, and using water-based flux (the water-based flux with the formula disclosed in Example 1 of CN120347425A) to cure 182TOPCon solar cells under the lamp of a string bonding machine at 150℃ / 20s, the adhesive point tensile strength of the solder ribbon was tested using a tensile tester.

[0039] The thermosetting adhesives prepared in Examples 1-4 and Comparative Examples 1-6 were subjected to the above tests, and the results are shown in Tables 3 and 4.

[0040] Table 3 Test Results of Thermosetting Adhesives Example 1 Example 2 Example 3 Example 4 Viscosity mPas 31589 33019 32670 33129 thixotropic 5.11 5.17 5.23 5.19 transmittance % ＞90 ＞90 ＞90 ＞90 TC90 / s 15 13 14 12 Adhesive dot pull force / N 0.32 0.35 0.37 0.38 Hardness / A 47 51 53 50 Tensile strength / MPa 4.3 4.5 4.1 4.7 Elongation at break / % 245 230 235 230 Thermosetting adhesive work time / h 9 8 9 9 Table 4 Test Results of Thermosetting Adhesives Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Viscosity / m·Pas 32349 32088 31947 33500 31499 34010 thixotropic 5.05 5.01 5.21 5.18 5.11 5.25 transmittance / % ＞90 ＞90 ＞90 ＞90 ＞90 ＞90 TC90 / s 21 23 21 20 24 25 Adhesive dot pull force / N 0.26 0.24 0.30 0.27 0.25 0.25 Hardness / A 50 49 51 52 48 53 Tensile strength / MPa 3.8 4.1 4.5 4.2 3.9 4.0 Elongation at break / % 240 235 242 247 238 231 Thermosetting adhesive work time / h 5 5 7 7 6 8 As shown in Table 1, the addition of the anti-poisoning agent effectively protects the catalyst, allowing the catalyst and inhibitor to achieve a balance between rapid curing and long workability when mixed in a suitable ratio. Furthermore, using both high-hydrogen-content and low-hydrogen-content silicone oils as components simultaneously satisfies the following requirements: dot tensile strength ≥ 0.3N, light transmittance > 90%, TC90 ≤ 15s, thixotropy > 5, and workability ≥ 8h. For the thermosetting adhesive used in OBB modules of N-type photovoltaic cells, the key performance characteristics are dot tensile strength, thixotropy, light transmittance, curing time, and workability. These only require simultaneously satisfying dot tensile strength ≥ 0.3N, light transmittance > 90%, TC90 < 20s, thixotropy > 5, and workability > 5h. Clearly, the thermosetting adhesive formulation provided by this invention offers faster curing speed and longer workability.

[0041] When the catalyst and inhibitor ratio is inappropriate, such as in Comparative Example 6, although the workability of the thermosetting adhesive reaches 8 hours, the curing speed is slow, exceeding 20 seconds, which does not meet the performance requirements for thermosetting adhesives used in photovoltaic N-type cell OBB modules. Furthermore, the use of single high-hydrogen-content silicone oils or single low-hydrogen-content silicone oils significantly reduces the properties of the thermosetting adhesive in all aspects. It is speculated that this may be because an appropriate content of high-hydrogen-content silicone oil, rich in Si-H bonds, allows more Pt to be stabilized, reducing the probability of Pt poisoning and resulting in superior thermosetting adhesive performance. In contrast, most silicone optical adhesives use single low-hydrogen-content silicone oils. For example, the photothermal dual-curing silicone liquid optical adhesive composition provided in CN110564360A contains only hydrogen-containing silicone oil with a hydrogen content of 0.01~0.3%.

Claims

1. A silicone thermosetting adhesive for use in photovoltaic N-type cell OBB modules, characterized in that, By weight, it includes: 10-35 parts of vinyl silicone oil 10-20 parts of low-hydrogen silicone oil 5-10 parts of high-hydrogen silicone oil 10-30 parts of vinyl MQ silicone resin Platinum catalyst 0.1-2 parts, Inhibitor 0.1-2 parts, Thixotropic agent 10-30 parts, 1-5 parts of tackifier 5-20 parts diluent 0.1-2 parts of coupling agent, 1-2 parts of anti-poisoning agent.

2. The organosilicon thermosetting adhesive as described in claim 1, characterized in that, The vinyl silicone oil is selected from at least one of end-capped vinyl silicone oil and double-capped vinyl silicone oil; the vinyl content of the vinyl silicone oil is 0.1~0.5wt%.

3. The organosilicon thermosetting adhesive as described in claim 1, characterized in that, The vinyl content of the vinyl MQ silicone resin is 0.5~1.5wt%.

4. The organosilicon thermosetting adhesive as described in claim 1, characterized in that, The mass ratio of the low-hydrogen-content silicone oil to the high-hydrogen-content silicone oil is 3:(1~2).

5. The organosilicon thermosetting adhesive as described in claim 1 or 4, characterized in that, The high-hydrogen-content silicone oil has a hydrogen content of 1.5~1.6wt%; the low-hydrogen-content silicone oil has a hydrogen content of 0.2~1.0wt%.

6. The organosilicon thermosetting adhesive as described in claim 1, characterized in that, The mass ratio of the inhibitor to the platinum catalyst is 1:(3~5).

7. The organosilicon thermosetting adhesive as described in claim 1 or 6, characterized in that, The inhibitor is an alkynyl alcohol inhibitor, and the platinum catalyst is a cassiterite catalyst.

8. The organosilicon thermosetting adhesive as described in claim 1, characterized in that, The anti-poisoning agent is aluminum di-sec-butoxyacetoacetate chelate and / or basic aluminum oxide.

9. The organosilicon thermosetting adhesive as described in claim 1, characterized in that, The thixotropic agent is a thermally conductive inorganic filler with a particle size of 30~500 nm, the coupling agent is a silane coupling agent, the diluent is light white oil, and the thickener is allyl glycidyl ether.

10. A method for preparing an organosilicon thermosetting adhesive for a photovoltaic N-type cell OBB module according to any one of claims 1 to 9, characterized in that, include: Vinyl silicone oil, vinyl MQ silicone resin, and thixotropic agent are mixed under heating conditions, cooled and degassed, and an inhibitor is added. Then, high-hydrogen silicone oil, low-hydrogen silicone oil, catalyst, tackifier, diluent, coupling agent, and anti-poisoning agent are added in portions, and the mixture is degassed again to obtain the final product.

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