Mixing tube anti-curing pouring sealant for junction box and preparation method thereof

Abstract

The invention provides a mixing tube anti-curing pouring sealant for a junction box, which comprises a component A and a component B. The component A comprises the following components in parts by mass: 430-600 parts of alpha, omega-hydroxyl-terminated polydimethylsiloxane, 80-120 parts of hydroxyl-terminated phenyl-methyl copolymer, 300-450 parts of filler, 23-30 parts of titanium dioxide, 2-6 parts of deep curing accelerator and 0-10 parts of methyl silicone oil; the component B comprises 30-60 parts of methyl silicone oil, 20-60 parts of a cross-linking agent, 5-20 parts of a coupling agent and 0.3-1 part of an organic tin catalyst. The viscosity of the hydroxyl-terminated phenyl-methyl copolymer ranges from 3000 mpa.s to 10000 mpa.s, and the content of phenyl ranges from 2.0 mol% to 15.0 mol%. The hydroxyl-terminated phenyl-methyl copolymer introduced in the invention can reduce the viscosity of the AB glue after mixing, reduce the residual amount of the mixed glue in a mixing pipe, and prolong the service time of the mixing pipe. Meanwhile, due to the introduction of the hydroxyl-terminated phenyl-methyl copolymer, the high-temperature and high-humidity resistance of the pouring sealant is further improved.

Description

Technical Field

[0001] This application relates to the field of potting compound materials, specifically to a hybrid anti-curing potting compound for junction boxes and its preparation method. Background Technology

[0002] Junction box potting compound is a special adhesive used to seal and protect the electronic components inside junction boxes. It typically consists of component A (containing siloxane groups) and component B (containing crosslinking agents and catalysts), which react chemically after mixing to form a three-dimensional network structure. Module manufacturers use mixing tubes in their potting equipment to mix components A and B. These mixing tubes are designed with spiral structures or static mixers. These structures increase the turbulence, shearing, and diffusion of the adhesive, causing the two components to be repeatedly cut and recombined during flow, ultimately forming a homogeneous mixture. During mixing, components A and B react fully, forming an active adhesive with curing capabilities. This residue can gradually clog the mixing tube, requiring production line shutdowns for replacement and severely impacting module production capacity. Therefore, developing a junction box mixing tube anti-curing potting compound that meets performance requirements, is easy to apply, has excellent weather resistance, and can extend the replacement time of the mixing tube has high economic value and practicality.

[0003] CN119684961A discloses a high-performance photovoltaic junction box potting compound and its preparation method. This invention adds a certain amount of hydroxyl-terminated polybutadiene and a deep curing agent to component A. The prepared potting compound has a short curing time and good weather resistance, adhesion and sealing properties, making it suitable for marine photovoltaic module encapsulation.

[0004] CN114525105A discloses a two-component silicone potting compound for photovoltaic junction boxes and its preparation method. This invention enhances the curing performance of the silicone potting compound by adding silane-modified polyether and using a high- and low-viscosity mixing method of α,ω-terminated hydroxyl polydimethylsiloxane, reduces the curing time, enhances the moisture resistance and high-temperature resistance of the silicone potting compound, and significantly improves the weather resistance of the silicone potting compound.

[0005] However, a comparative analysis of the above patents reveals that none of them address the optimization of the workability time after mixing the A and B components of the potting compound, nor do they consider the impact of the potting compound curing in the mixing tube on its application performance. Summary of the Invention

[0006] To address the above problems, this invention provides a hybrid anti-curing potting compound for junction boxes, comprising component A and component B. By weight, component A comprises: 430-600 parts of α,ω-terminated hydroxyl polydimethylsiloxane, 80-120 parts of hydroxyl-terminated phenyl-methyl copolymer, 300-450 parts of filler, 23-30 parts of titanium dioxide, 2-6 parts of deep curing accelerator, and 0-10 parts of methyl silicone oil. Component B comprises: 30-60 parts methyl silicone oil, 20-60 parts crosslinking agent, 5-20 parts coupling agent, and 0.3-1 parts organotin catalyst.

[0007] Furthermore, the viscosity of the α,ω-terminated hydroxyl polydimethylsiloxane is 1500 mpa.s to 5000 mpa.s.

[0008] Furthermore, the viscosity of the hydroxyl-terminated phenyl-methyl copolymer is 3000 mPa·s to 10000 mPa·s, and the phenyl content is 2.0-15.0 mol%. The specific preparation method is as follows: (1) Mix 60-80 parts of α,ω-terminated hydroxyl polydimethylsiloxane and 5-50 parts of octaphenylcyclotetrasiloxane and heat to 110℃-130℃, then stir under vacuum to remove water; (2) Add alkaline gum as a catalyst and stir the reaction at 140℃-160℃ for 6-10 hours under inert gas protection; (3) Add acid glue dropwise and stir until the system is neutral. Then heat to 160℃-180℃ and stir under vacuum to remove the low-boiling substances. After cooling, hydroxyl-terminated phenyl-methyl copolymer is obtained. The acidic adhesive is phosphoric acid or phosphate silanol.

[0009] Furthermore, the filler is one or more of stearic acid modified aluminum hydroxide, stearic acid modified silica powder, or stearic acid modified nano-calcium carbonate.

[0010] Furthermore, the viscosity of the methyl silicone oil is 5 mpa.s to 350 mpa.s.

[0011] Furthermore, the crosslinking agent is one or more of tetraethyl orthosilicate, methyltriethoxysilane, methyltrimethoxysilane, or vinyltrimethoxysilane.

[0012] Furthermore, the coupling agent is one or both of γ-aminopropyltriethoxysilane or N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0013] Furthermore, the deep curing accelerator is one or more of hydrated alumina, deionized water, or hydrated calcium sulfate.

[0014] Furthermore, the organotin catalyst is dibutyltin dilaurate.

[0015] This invention also provides a method for preparing a curing-resistant potting compound for junction boxes, comprising the following steps: (1) Preparation of A glue: First, mix α,ω-terminated hydroxyl polydimethylsiloxane and hydroxyl-terminated phenyl-methyl copolymer and heat to 105-115℃, stir evenly under vacuum, and cool to obtain base glue; add filler, titanium dioxide and methyl silicone oil to base glue and stir evenly; then continue to add deep curing accelerator and stir evenly; then filter after vacuum degassing to obtain A glue; Preparation of Glue B: Mix the B component materials evenly to obtain Glue B; (2) Mix A and B glue evenly at a mass ratio of (5-7):1 to obtain potting compound.

[0016] The beneficial effects of this invention are as follows: This invention introduces a hydroxyl-terminated phenyl-methyl copolymer into the potting compound formulation. An appropriate amount of phenyl groups in the copolymer creates steric hindrance, slightly reducing the reactivity of the terminal hydroxyl groups, thus slowing down the curing speed, effectively extending the gel time and workability, reducing the viscosity of the AB adhesive mixture, minimizing the amount of residue in the mixing tube, and extending the service life of the mixing tube. Simultaneously, the introduction of the hydroxyl-terminated phenyl-methyl copolymer further improves the potting compound's resistance to high temperatures and humidity. Detailed Implementation

[0017] The embodiments of the present invention will be described in detail below with reference to the examples. The following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

[0018] Example 1 Preparation of hydroxyl-terminated phenyl-methyl copolymers: (1) 70 parts of α,ω-terminated hydroxyl polydimethylsiloxane with 8% hydroxyl mass fraction and 10 parts of octaphenylcyclotetrasiloxane were mixed in a planetary machine and heated to 120°C, vacuum degree -0.095 MPa, and stirring at 150 rpm for 3 hours to remove water. (2) Add 4 parts of potassium hydroxide alkaline gel (potassium hydroxide mass fraction is 2%) as a catalyst, and stir for 8 hours at 150°C and 150 rpm under nitrogen protection; (3) Add phosphoric acid dropwise and stir until the system is neutral. Then heat to 170°C, vacuum degree -0.095 MPa, speed 150 rpm and stir for 2 hours to remove the low boiling substances. After cooling, hydroxyl-terminated phenyl-methyl copolymer with 2% phenyl content is obtained.

[0019] Example 2 Unlike Example 1, in step (1), 20 parts of octaphenylcyclotetrasiloxane were used, and the rest were the same as in Example 1, resulting in a hydroxyl-terminated phenyl-methyl copolymer with a phenyl content of 5%.

[0020] Example 3 Unlike Example 1, in step (1), 50 parts of octaphenylcyclotetrasiloxane and 60 parts of α,ω-terminated hydroxyl polydimethylsiloxane were used, and the rest were the same as in Example 1, to obtain a hydroxyl-terminated phenyl-methyl copolymer with a phenyl content of 15%.

[0021] Example 4 Unlike Example 1, step (3) was omitted to obtain an alkaline hydroxyl-terminated phenyl-methyl copolymer, while the rest was the same as in Example 1.

[0022] Example 5 A hybrid anti-curing potting compound for junction boxes, comprising component A and component B, with the following formulation: Component A 1500 mPa·s α,ω-terminated hydroxyl polydimethylsiloxane: 505 parts; 3000 mPa.s 2.0 mol% hydroxyl-terminated phenyl-methyl copolymer (prepared in Example 1): 100 parts; 5μm stearic acid modified aluminum hydroxide: 360 parts; Titanium dioxide: 29 parts; 10 mPa·s methyl silicone oil: 5 parts; Hydrated alumina (deep curing accelerator): 1 part; Component B 100 mPa·s dimethyl silicone oil: 40 parts; Methyltriethoxysilane (crosslinking agent): 30 parts; Vinyltriethoxysilane (crosslinking agent): 22 parts; γ-aminopropyltriethoxysilane (coupling agent): 4 parts; N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (coupling agent): 4 parts; Dibutyltin dilaurate: 0.4 parts; The preparation method is as follows: Glue A: According to the formulation of component A, α,ω-terminated hydroxyl polydimethylsiloxane and hydroxyl-terminated phenyl-methyl copolymer are first mixed in a planetary mixer and heated to 110°C, with a vacuum of -0.095 MPa and a stirring speed of 150 rpm for 40 min. After cooling, the base glue is obtained. Stearic acid modified aluminum hydroxide, titanium dioxide and methyl silicone oil are added to the base glue and mechanically stirred at 1500 rpm for 45 min. Then, a deep curing accelerator is added to the colloid, and the planetary mixer is stirred at 180 rpm for 30 min without vacuum. The vacuum is then turned on to a vacuum of -0.095 MPa, and after degassing for 5 min, the mixture is filtered to obtain glue A.

[0023] Component B: Under a vacuum of -0.095 MPa, the materials of Component B are mixed in a planetary mixer and stirred at 100 rpm for 30 min to obtain Glue B.

[0024] Mix A and B adhesives at a mass ratio of 6:1 for 2 minutes to obtain a mixed anti-curing potting compound for junction boxes.

[0025] Example 6 Unlike Example 5, the hydroxyl-terminated phenyl-methyl copolymer was prepared in Example 2, and the rest were the same as in Example 5.

[0026] Example 7 Unlike Example 5, the hydroxyl-terminated phenyl-methyl copolymer was prepared in Example 3, while the rest was the same as in Example 5.

[0027] Example 8 Unlike Example 5, the hydroxyl-terminated phenyl-methyl copolymer was prepared in Example 4, and the rest were the same as in Example 5.

[0028] Comparative Example 1 The difference from Example 5 is that 100 parts of hydroxyl-terminated phenyl-methyl copolymer were replaced with 100 parts of 3000 mPa·s α,ω-terminated hydroxyl polydimethylsiloxane, and the rest were the same as in Example 5.

[0029] Viscosity tests were performed on the newly prepared A-type adhesives from Examples 5-8 and Comparative Example 1. The newly prepared A-type adhesives were placed in an environment of (23±2)℃ and (50±5)% humidity for 2 months to observe whether stratification occurred. The newly prepared A-type adhesives were mixed with B-type adhesives, and the surface drying time, workable time, gel time, and mixed viscosity were recorded. The mixed viscosity was the viscosity measured immediately after mixing A-type adhesives and B-type adhesives for 2 minutes. The surface drying time was recorded after mixing A-type adhesives and B-type adhesives that had been placed for 2 months. The measurement results are shown in Table 1.

[0030] Table 1

[0031] After mixing the newly prepared A glue with B glue, the flowability, leveling properties, tensile strength, elongation at break, cohesive failure rate of the junction box, appearance after HAST96, and tensile strength retention rate after HAST96 were measured. The test results are shown in Table 2.

[0032] Table 2

[0033] The following are the test methods for performance parameters involved in this invention: (1) Viscosity: The viscosity of component A before mixing and the viscosity of component AB after mixing are tested according to GB-T 2794-2013.

[0034] (2) Surface drying time: determined according to standard GB / T 7123.2-2023.

[0035] (3) Gel time: Measured according to standard Q / SJTSX003, the container is upright and the colloid is vertical without bulging.

[0036] (4) Working time: Under the condition of qualified viscosity, pour 200 g of well-stirred mixed potting compound into a 250 mL beaker and measure its viscosity according to GB-T 2794-2013 standard. Record the time when the viscosity is greater than 30000 mPa·s as the working time.

[0037] (5) Flow leveling: Prepare a soft nozzle with a length of 105±5 mm and a diameter of 3.0±0.1 mm; a glass plate with a circular scale: diameter 0-100 mm; keep the lower edge of the nozzle 2 cm away from the glass plate.

[0038] Block the flexible nozzle, align the center of the nozzle with the target of the circular graduated glass plate, pour in >10 mL of potting compound that has been manually mixed with components AB for 2 minutes, loosen the nozzle, and record the time it takes for 10 mL of potting compound to flow out as the outflow time, and the time it takes for 10 mL of potting compound to reach a leveling diameter of 75 mm as the leveling time.

[0039] (6) Tensile strength: The tensile strength of the potting compound was tested according to GB / T 528-2009.

[0040] (7) Elongation at break: The elongation at break of the potting compound was tested according to GB / T 528-2009.

[0041] (8) Adhesion performance: After curing for 7 days at (23±2)℃ and (50±5)% humidity, the adhesion performance between the two-component silicone potting compound and the junction box was tested according to GB / T 29595. (9) High temperature and high humidity resistance: At a temperature of 105℃, a humidity of 100%RH, and a pressure of 1.21 kg / cm², the resistance is maintained at a constant temperature and humidity. 2 Under these conditions, the potting junction box is kept for 96 hours, and then observed for any signs of powdering, cracking, or yellowing.

[0042] Results analysis: The test results in Table 1 show that the A-type adhesives in Examples 5 and 6 did not exhibit stratification after standing for two months, and their surface drying time remained essentially unchanged. This indicates that the appropriate introduction of hydroxyl-terminated phenyl-methyl copolymers into the A-type adhesive does not adversely affect its shelf life. After mixing the A and B components, the steric hindrance caused by the appropriately introduced phenyl groups effectively prolongs the gel time and workability of the mixed adhesive, reduces the mixed viscosity, and thus effectively reduces the amount of the mixed adhesive remaining in the mixing tube, extending the service life of the mixing tube. However, as shown in Example 7, the hydroxyl-terminated phenyl-methyl copolymer with high phenyl content has poor compatibility with α,ω-terminated hydroxyl polydimethylsiloxane, and stratification occurs upon standing, severely affecting the product's shelf life.

[0043] The test results in Table 2 show that the introduction of hydroxyl-terminated phenyl-methyl copolymer effectively improved the weather resistance of the cured colloid. The colloid aged with HAST96 still maintained a good sealing effect on the junction box, and the tensile strength retention rate of the colloid was significantly improved. In Examples 5 and 6, the outflow and leveling time was shortened, indicating that the introduction of hydroxyl-terminated phenyl-methyl copolymer helped to slow down the expansion and tackification rate of the mixed colloid, effectively accelerating the outflow rate and enabling rapid leveling. This is corroborated by the relevant test results in Table 1.

[0044] The copolymer used in Example 8 was not neutralized with phosphoric acid. After HAST96, it pulverized and cracked. This was because the residual alkaline substances in the copolymer catalyzed the rearrangement and breakage of silicon-oxygen bonds, resulting in irreversible breakage of the silicone rubber main chain. During the wet heat aging process, it quickly became brittle and powdery, affecting the reliability of the product.

Claims

1. A curing-resistant potting compound for junction boxes, characterized in that, Including component A and component B, component A comprises, by mass parts: 430-600 parts of α,ω-terminated hydroxyl polydimethylsiloxane, 80-120 parts of hydroxyl-terminated phenyl-methyl copolymer, 300-450 parts of filler, 23-30 parts of titanium dioxide, 2-6 parts of deep curing accelerator, and 0-10 parts of methyl silicone oil. Component B comprises: 30-60 parts methyl silicone oil, 20-60 parts crosslinking agent, 5-20 parts coupling agent, and 0.3-1 parts organotin catalyst.

2. The anti-curing potting compound for junction boxes according to claim 1, characterized in that, The viscosity of the α,ω-terminated hydroxyl polydimethylsiloxane is 1500 mpa.s to 5000 mpa.s.

3. The anti-curing potting compound for junction boxes according to claim 1, characterized in that, The hydroxyl-terminated phenyl-methyl copolymer has a viscosity of 3000 mPa·s to 10000 mPa·s and a phenyl content of 2.0-15.0 mol%. The specific preparation method is as follows: (1) Mix 60-80 parts of α,ω-terminated hydroxyl polydimethylsiloxane and 5-50 parts of octaphenylcyclotetrasiloxane and heat to 110℃-130℃, then stir under vacuum to remove water; (2) Add alkaline gum as a catalyst and stir the reaction at 140℃-160℃ for 6-10 hours under inert gas protection; (3) Add acid glue dropwise and stir until the system is neutral. Then heat to 160℃-180℃ and stir under vacuum to remove the low-boiling substances. After cooling, hydroxyl-terminated phenyl-methyl copolymer is obtained. The acidic adhesive is phosphoric acid or phosphate silanol.

4. The anti-curing potting compound for junction boxes according to claim 1, characterized in that, The filler is one or more of stearic acid modified aluminum hydroxide, stearic acid modified silica powder, or stearic acid modified nano calcium carbonate.

5. The anti-curing potting compound for junction boxes according to claim 1, characterized in that, The viscosity of the methyl silicone oil is 5 mpa.s to 350 mpa.s.

6. The anti-curing potting compound for junction boxes according to claim 1, characterized in that, The crosslinking agent is one or more of tetraethyl orthosilicate, methyltriethoxysilane, methyltrimethoxysilane, or vinyltrimethoxysilane.

7. The anti-curing potting compound for junction boxes according to claim 1, characterized in that, The coupling agent is one or both of γ-aminopropyltriethoxysilane or N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

8. The anti-curing potting compound for junction boxes according to claim 1, characterized in that, The deep curing accelerator is one or more of hydrated alumina, deionized water, or hydrated calcium sulfate.

9. The anti-curing potting compound for junction boxes according to claim 1, characterized in that, The organotin catalyst is dibutyltin dilaurate.

10. A method for preparing a hybrid tube anti-curing potting compound for junction boxes according to any one of claims 1-9, characterized in that, Includes the following steps: (1) Preparation of A glue: First, mix α,ω-terminated hydroxyl polydimethylsiloxane and hydroxyl-terminated phenyl-methyl copolymer and heat to 105-115℃, stir evenly under vacuum, and cool to obtain base glue; add filler, titanium dioxide and methyl silicone oil to base glue and stir evenly; then continue to add deep curing accelerator and stir evenly; then filter after vacuum degassing to obtain A glue; Preparation of Glue B: Mix the B component materials evenly to obtain Glue B; (2) Mix A and B glue evenly at a mass ratio of (5-7):1 to obtain potting compound.

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