A quick-curing anti-aging silicone sealant for photovoltaic modules and a preparation method thereof

Abstract

The application relates to the field of sealant materials, and particularly discloses a fast-curing anti-aging silicone sealant for photovoltaic modules and a preparation method thereof. The fast-curing anti-aging silicone sealant for photovoltaic modules comprises the following raw materials in parts by weight: alpha, omega-dihydroxypolydimethylsiloxane 360-450 parts, nano active calcium carbonate 275-425 parts, modified silicon powder 130-280 parts, hydrophobic fumed silica 510 parts, crosslinking agent 30-40 parts, coupling agent 5-10 parts, and dibutyltin dilaurate 0.1-0.4 part. The fast-curing anti-aging silicone sealant for photovoltaic modules is prepared by compounding 20,000 mpa.s and 500,000 mpa.s alpha, omega-dihydroxypolydimethylsiloxane, introducing hydrophobic fumed silica and modified silicon powder, and adjusting the types, adding sequence and reaction time of the additives, so that the construction performance, curing rate and anti-aging performance of the sealant are improved.

Description

Technical Field

[0001] The present application relates to the field of sealant materials, and in particular to a fast-curing anti-aging silicone sealant for photovoltaic modules. Background Art

[0002] Sealant for photovoltaic modules is a polymer material with high elasticity, high adhesion, and low expansion. It combines with moisture in the air at room temperature to cause crosslinking, vulcanizing into a high-performance elastomer with excellent bonding and sealing properties for both metals and non-metallic materials. It is primarily used for sealing and bonding between solar panels and backsheets, between solar panels and glass, and between frames and solar panels. Currently, the predominant frame adhesive used in the photovoltaic industry is still a single-component deoximized silicone sealant. Its curing is a physical property change that occurs upon contact with moisture. This product cures slowly, significantly reducing assembly efficiency on the production line and making secondary adhesive overflow more likely. During the assembly process, sealants with suitable extrudability offer better application performance. Their excellent anti-aging properties ensure that modules can be used in a variety of harsh environments. Therefore, developing a fast-curing, easy-to-apply, fast-setting, anti-aging silicone sealant for photovoltaic modules is both economically valuable and practical.

[0003] Chinese invention patent application publication CN108048030A discloses a method for preparing a solar photovoltaic module sealant, comprising the following raw materials by weight: 70-80 parts polyorganosiloxane, 20-30 parts filler, 5-15 parts catalyst, 5-15 parts tackifier, 3-9 parts plasticizer, 2-6 parts flame retardant, and 1-6 parts crosslinking agent. The polyorganosiloxane is a hydroxyl-terminated polydimethylsiloxane with a room temperature viscosity of 10,000-100,000 MPa.s. The filler is a mixture of light calcium carbonate, heavy calcium carbonate, nano-calcium carbonate, and fumed silica. The tackifier comprises an isocyanate-modified alkyd resin and castor oil. The flame retardants are aluminum hydroxide and magnesium hydroxide, and the aluminum hydroxide and magnesium hydroxide are modified with fatty acids, silane coupling agents, or resin acids. By adding the tackifier and plasticizer to the base material, the sealant produced has good bonding properties and stability.

[0004] Chinese invention patent application publication CN103232832A discloses a fast-curing sealant for solar photovoltaic modules. Its raw material composition includes 100 parts of α,ω-dihydroxypolydimethylsiloxane, 60-80 parts of nano-activated calcium carbonate, 5-10 parts of fumed silica, 1-5 parts of an anti-yellowing agent, 1-5 parts of a coupling agent, 10-20 parts of a crosslinking agent, 0.1-2 parts of a catalyst A, 0.001-0.1 parts of a catalyst B, and 1-10 parts of a silicone oil plasticizer. The catalyst A is an organotin chelate, and the catalyst B is dioctyltin dilaurate. This sealant cures quickly, resists yellowing, exhibits good aging resistance, and exhibits broad adhesion to substrates.

[0005] A comparative analysis of the above patents shows that none of them optimizes the extrudability, curing depth and aging at the same time. In order to meet the market demand, the inventors have studied an anti-aging photovoltaic adhesive with good construction performance, excellent performance, fast curing speed and simple preparation method, so as to better meet the actual application needs of the solar photovoltaic module industry. Summary of the Invention

[0006] The present invention aims to reduce the primary overflow probability of existing sealants and improve assembly efficiency, thereby ensuring component reliability. By compounding a filler with α,ω-dihydroxypolydimethylsiloxane and adjusting the order of addition and reaction time of the additives, hydrophobic fumed silica is introduced, thereby simultaneously increasing the sealant's curing rate and adjusting its extrudability. Modified silica powder is used to partially replace activated nano-calcium carbonate, and the type, order of addition, and reaction time of the additives are adjusted to improve the sealant's workability, curing rate, and anti-aging properties. To this end, the present invention provides a fast-curing, anti-aging silicone sealant for photovoltaic modules and a preparation method thereof, comprising the following raw materials in parts by weight: 360-450 parts of α,ω-dihydroxypolydimethylsiloxane, 275-425 parts of nano-activated calcium carbonate, 130-280 parts of modified silica powder, 5-10 parts of hydrophobic fumed silica, 30-40 parts of a crosslinking agent, 5-10 parts of a coupling agent, and 0.1-0.4 parts of dibutyltin dilaurate.

[0007] The α,ω-dihydroxy polydimethylsiloxane comprises 330-375 parts of 10,000-20,000 mPa.s α,ω-dihydroxy polydimethylsiloxane and 30-75 parts of 400,000-700,000 mPa.s α,ω-dihydroxy polydimethylsiloxane.

[0008] Preferably, the crosslinking agent is one or a combination of two of methyltributylanoxime silane, vinyltributylanoxime silane, and D-31 methyl mixed ketoxime crosslinking agent.

[0009] The coupling agent is one or a combination of γ-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0010] As a further optimization, the viscosity of the α,ω-dihydroxypolydimethylsiloxane at room temperature is 10,000-20,000 mPa.s and 400,000-700,000 mPa.s.

[0011] In some preferred cases, the viscosity of the α,ω-dihydroxypolydimethylsiloxane at room temperature is 20,000 mPa.s and 500,000 mPa.s.

[0012] α,ω-dihydroxypolydimethylsiloxanes with a molecular weight of 400,000-700,000 mPa.s have longer molecular chains and stronger intermolecular forces, resulting in a higher macroscopic viscosity. This can be used to adjust the sealant's workability. Furthermore, long-chain molecules are more likely to entangle with each other during crosslinking, forming a more complex and stable three-dimensional network structure. Furthermore, the hydroxyl content of α,ω-dihydroxypolydimethylsiloxanes with a molecular weight of 400,000-700,000 mPa.s is lower than that of α,ω-dihydroxypolydimethylsiloxanes with a molecular weight of 10,000-20,000 mPa.s, which can be used to adjust the hydroxyl value and ensure complete crosslinking of all active sites. Using a higher ratio of α,ω-dihydroxypolydimethylsiloxanes with a molecular weight of 10,000-20,000 mPa.s to α,ω-dihydroxypolydimethylsiloxanes with a molecular weight of 400,000-700,000 mPa.s can improve the sealant's mechanical and workability, and exhibit better mechanical property retention after aging.

[0013] Preferably, the filler is a mixture of nano-calcium carbonate, modified silica powder and fumed silica, and the moisture content of the fumed silica is less than 0.6%. Fumed silica has a good filling effect and can effectively improve the initial mechanical properties of the sealant.

[0014] Preferably, the nano-active calcium carbonate is stearic acid-modified nano-calcium carbonate with a D50 of 2 μm.

[0015] Preferably, the modified silicon powder D50=5-10 m, using 30-35wt% H2O2 to activate the silicon powder with hydroxyl groups, using chemical vapor deposition, under anhydrous conditions, siloxane bonds directly react with the -OH groups on the surface of the silicon powder to form strong Si-O-Si covalent bonds, which are grafted onto the surface of the silicon powder and fully hydrophobically modified. Moreover, under anhydrous conditions, no condensation occurs between the molecules of the modifier, making it easier to modify the monolayer compared to the liquid phase method. Silicon powder is superior to calcium carbonate in terms of chemical stability, thermal stability, and strengthening effect. Calcium carbonate has relatively weak weather resistance and is prone to chemical reactions in acidic environments.

[0016] A method for preparing modified silicon powder, specifically comprising the following steps:

[0017] Step 1: 1000-1250 mesh silicon powder is uniformly mixed with 400 mL of 30-35 wt% H2O2, and then stirred and condensed under reflux at a temperature of 105-115°C for 3-5 h to obtain a hydroxyl-activated silicon powder solution;

[0018] Step 2: The powder obtained by filtering the silicon powder solution is dried at 100-120°C for 3-4 h, and then crushed to obtain hydroxyl-activated silicon powder with a D50 of 5-10 μm;

[0019] Step 3: Based on chemical vapor deposition, the hydroxyl-activated silicon powder is placed in a tray and a container containing a modifier in a vacuum oven, the amount of the modifier added is 20% of the mass of the silicon powder, heated to 110-130°C for 0.5-1 h, and the vapor deposition process is carried out, the hydrophobic modification is completed, and then the excess gaseous modifier is removed by vacuum pumping, and the modified silicon powder is obtained after cooling. 50%, heated to 110-130°C for 0.5-1 h, and the vapor deposition process is carried out, the hydrophobic modification is completed, and then the excess gaseous modifier is removed by vacuum pumping, and the modified silicon powder is obtained after cooling.

[0020] The modifier is one or more of dimethyldiethylsilane, vinyltrimethoxysilane (SCA-1603), vinylmethyldimethoxysilane, and aminoethylaminopropylmethyldimethoxysilane.

[0021] The application provides a preparation method of a photovoltaic module fast-curing anti-aging silicone sealant, specifically comprising the following steps:

[0022] Step 1: α, ω-dihydroxypolydimethylsiloxane, nano active calcium carbonate and modified silicon powder are mixed in a planetary machine at a speed of 60-80 rpm, heated to 120-130°C, vacuum degree-0.095 MPa, stirring speed 80-120 rpm, and water removal is carried out for 3-4 h to obtain a base material with a water content of less than 0.01%. 4 h.

[0023] Step 2: Hydrophobic fumed white carbon black is added to the cooled base material at a speed of 60-80 rpm, and then stirred at a speed of 80-120 rpm under a vacuum degree of-0.095 MPa. 120 rpm.

[0024] Step 3: The crosslinking agent is added to the cooled base material and mixed uniformly, and stirred at a speed of 80-120 rpm under a vacuum degree of-0.095 MPa.

[0025] Step 4: The coupling agent and catalyst are added to the base material, and stirred at a speed of 80-120 rpm under a vacuum degree of-0.095 MPa to obtain the photovoltaic module fast-curing anti-aging silicone sealant.

[0026] The advantages of the present application are embodied in:

[0027] (1) 10000 20000 mpa.s and 400000 700000 mpa.s α, ω-dihydroxy polydimethylsiloxane is used in combination, which significantly improves the elasticity and construction performance of the sealant;

[0028] (2) The modified silica powder and hydrophobic fumed silica are introduced to replace part of the nano calcium carbonate as the filler, which can improve the mechanical properties of the sealant and make it have better weather resistance;

[0029] (3) The crosslinking agent compounded by vinyl tributylketoxime silane and D-31 methyl mixed ketoxime crosslinking agent has high activity, which can effectively improve the curing depth of the sealant and shorten the surface drying time to 5 6 min;

[0030] (4) The present application uses low-cost, safe and non-toxic 30 35wt% H2O2 to activate the hydroxyl group of the unmodified silica powder, so as to facilitate the reaction with the modifier and improve the grafting rate. The modification is carried out by chemical vapor deposition method, which can timely remove the residual modifier and the modified product, avoid the formation of multiple layers of physical adsorption of excessive modifier on the surface of the silica powder, affect the modification effect, and at the same time reduce the modification cost. DETAILED DESCRIPTION

[0031] The following is a specific embodiment of the present application, which further describes the technical solutions of the present application to make the understanding of the present application more accurate and comprehensive, but the present application is not limited to these embodiments.

[0032] Example 1 7 provides a preparation method of a photovoltaic module fast curing type anti-aging silicone sealant, which is described below by taking example 1.

[0033] Example 1

[0034] Preparation of vinyl trimethoxysilane modified silica powder:

[0035] Step 1: Take 2 g of 1250 mesh unmodified silica powder and 400 mL of 35wt% H2O2, mix them evenly in a three-necked flask, and then stir and condense under reflux at a temperature of 110℃ for 4 h to obtain a hydroxyl-activated silica powder solution;

[0036] Step 2: After the silica powder solution is filtered, the powder obtained is dried at 120℃ for 3 h, and then crushed to obtain hydroxyl-activated silica powder with D50=10 m.

[0037] Step3 Based on chemical vapor deposition method, the hydroxyl-activated silicon powder is placed in the tray and the beaker containing SCA-1603 modifier is placed in the vacuum oven at the same time. The added amount of modifier is 30% of the mass of silicon powder. Hydrophobic modification is completed by heating to 130℃ for 0.5h. After vacuumizing, the excess gaseous modifier is removed. After cooling, SCA-1603 modified silicon powder is obtained.

[0038] Preparation of fast-curing anti-aging silicone sealant for photovoltaic module

[0039] Step1 350 parts of 20000 mpa.s α,ω-dihydroxypolydimethylsiloxane, 50 parts of 500000 mpa.s α,ω-dihydroxypolydimethylsiloxane, 260 parts of nano active calcium carbonate and 260 parts of SCA-1603 modified silicon powder are mixed in a planetary machine at a speed of 80 rpm for 30 min, then heated to 130℃, vacuum degree-0.095 MPa, stirring speed 120 rpm, water removal for 3h to obtain a base material, the water content is less than 0.01%, which ensures the storage period of the sealant;

[0040] Step2 10 g of hydrophobic fumed white carbon black is added to the cooled base material, mixed at a speed of 80 rpm for 15 min, then stirred at a speed of 120 rpm for 30 min under a vacuum degree of-0.095 MPa;

[0041] Step3 25 parts of vinyl tributyl ketoxime silane and 10 parts of D-31 methyl mixed ketoxime crosslinking agent are added to the cooled base material, and stirred at a speed of 100 rpm for 15 min under vacuum condition;

[0042] Step4 5 parts of γ-aminopropyl triethoxysilane, 3 parts of N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane and 0.3 parts of dibutyl tin dilaurate are added to the base material, and stirred at a speed of 100 rpm for 15 min under vacuum condition to obtain a fast-curing anti-aging silicone sealant for photovoltaic module.

[0043] Example 2

[0044] The difference between Example 2 and Example 1 is that the silicon powder is not activated by H2O2.

[0045] Example 3

[0046] The difference between Example 3 and Example 1 is that the silicon powder used is unmodified silicon powder.

[0047] Example 4

[0048] The difference between Example 4 and Example 1 is that no nano active calcium carbonate is added.

[0049] Example 5

[0050] The difference between Example 5 and Example 1 lies in the modification method of the silicon micropowder after the activation of the hydroxyl groups.

[0051] The specific modification method is as follows: 20 g of hydroxyl-activated silica powder and 1 g of SCA-1603 modifier are added to a mixed solution of 400 g of ethanol and deionized water in a mass ratio of 1:9, placed in a three-necked flask, and refluxed under high-speed stirring at 80 ° C in a water bath for 2 h to complete the modification. The modified silica powder is washed three times with deionized water and ethanol respectively, filtered, placed in a vacuum drying oven, dried at 80 ° C for 4 h, and crushed to obtain D50 = 10 m's SCA-1603 modified silica powder.

[0052] Example 6

[0053] The difference between Example 6 and Example 1 is that 130 parts of SCA-1603 modified silicon powder are added.

[0054] Example 7

[0055] The difference between Example 7 and Example 1 is that 50 parts of 500,000 mpa.s α,ω-dihydroxypolydimethylsiloxane are not added, and the added amount of 20,000 mpa.s α,ω-dihydroxypolydimethylsiloxane is 400 parts.

[0056] Comparative Example 1

[0057] Step 1: Mix 400 parts of 20,000 mpa.s α,ω-dihydroxypolydimethylsiloxane and 520 parts of nano-activated calcium carbonate at 80 rpm for 30 minutes, then heat to 130°C, vacuum -0.095 MPa, and stir at 120 rpm to remove water for 3 hours to prepare the base material with a moisture content of less than 0.01% to ensure the shelf life of the sealant.

[0058] Step 2: Add 17.5 parts of vinyltributylanoxime silane and 17.5 parts of methyltributylanoxime silane to the base material cooled to room temperature, and stir at 100 rpm for 15 minutes under vacuum conditions.

[0059] Step 3: Add 5 parts of γ-aminopropyltriethoxysilane, 3 parts of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and 0.2 parts of dibutyltin dilaurate to the base material. Stir at 100 rpm for 15 minutes under vacuum conditions to obtain a silicone sealant for photovoltaic modules.

[0060] According to Example 1 The photovoltaic module fast-curing anti-aging silicone sealant prepared in Example 7 and Comparative Example 1 was subjected to the following performance tests, and the test results are shown in Table 1.

[0061] Extrusion rate: reflects the construction performance of sealant extrusion, expressed as the time required to extrude 20 g of sealant, with the nozzle extrusion port inner diameter of 3 mm and the pressure of 0.5 MPa;

[0062] Surface drying time: reflects the time it takes for the sealant surface to become non-sticky, in accordance with GB / T 13477.5-2002;

[0063] Tensile strength: in accordance with GB / T 528-2009;

[0064] Elongation at break: in accordance with GB / T 528-2009;

[0065] Shear strength: Anodized aluminum Al-Al, in accordance with GB / T 7124-2008;

[0066] Curing depth (mm): in accordance with GB / T 29595-2013, test conditions 23℃±2℃ / RH (50±5)%;

[0067] Heat and humidity aging test: This is a reliability test conducted under harsh conditions with a temperature of 85°C and a humidity of 85%. It is mainly used to test the heat and humidity resistance and overall reliability of the product in harsh environments with high temperature and high humidity. The aging time is usually 1000 hours (DH1000). Example 1 8 and the sealant of comparative example 1 were prepared into 200 mm 200mm 2 mm silicone sheets were subjected to wet heat aging (DH1000) and then subjected to tensile strength test in accordance with GB / T 528-2009. The retention rates before and after aging were calculated.

[0068] Table 1

[0069]

[0070] From the data in Table 1, it can be seen that the photovoltaic module fast-curing silicone sealant of the present invention (Example 1 7) Compared with the sealant using methyl tributylidene oxime silane (Comparative Example 1), it has a faster curing speed, more suitable extrusion performance and higher mechanical property retention rate, meeting the needs of component factories for improved assembly efficiency and easy construction, reducing the probability of primary and secondary glue overflow, and ensuring the service life and reliability of the components.

[0071] The present invention introduces an appropriate amount of 500,000 mpa.s α,ω-dihydroxypolydimethylsiloxane on the basis of the original formula to improve elasticity and adjust the hydroxyl value. Compared with Example 7, it can be seen that the appropriate amount of 500,000 mpa.s α,ω-dihydroxypolydimethylsiloxane effectively improves the elasticity of the colloid.

[0072] As shown in Table 1 for extrudability and tensile strength, the present invention improves the sealant's extrusion performance by adding an appropriate amount of hydrophobic fumed silica. The combination of the two coupling agents effectively enhances the sealant's adhesion to the substrate, resulting in higher shear strength.

[0073] The difference in mechanical property retention after the heat and humidity aging test fully demonstrates that the introduction of an appropriate amount of modified silica powder can effectively prevent the mechanical property degradation of silica gel after aging, and has little impact on the initial mechanical properties. The hydroxyl-activated silica powder is more fully modified and has a better anti-aging effect. However, excessive use of silica powder can cause the colloid to become brittle and reduce elongation.

[0074] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A fast-curing anti-aging silicone sealant for photovoltaic modules, characterized in that: The invention comprises the following raw materials in parts by weight: 360-450 parts of α,ω-dihydroxy polydimethylsiloxane, 275-425 parts of nano-activated calcium carbonate, 130-280 parts of modified silicon micropowder, 5-10 parts of hydrophobic fumed silica, 30-40 parts of a crosslinking agent, 5-10 parts of a coupling agent, and 0.1-0.4 parts of dibutyltin dilaurate, wherein the α,ω-dihydroxy polydimethylsiloxane comprises 330-375 parts of 10,000-20,000 mPa.s α,ω-dihydroxy polydimethylsiloxane and 30-75 parts of 400,000-700,000 mPa.s α,ω-dihydroxy polydimethylsiloxane. Preparation method of modified silicon micropowder, specifically The following steps are involved: Step 1: Mix the silicon micropowder and 30-35wt% H2O2 evenly, and then stir and reflux at 105℃~115℃ for 3-5 hours to obtain a silicon micropowder solution after hydroxyl activation; Step 2: The powder obtained after filtering the silica powder solution is dried and crushed to obtain hydroxyl-activated silica powder; Step 3: Based on the chemical vapor deposition method, the hydroxyl-activated silica powder and the modifier are placed in a sealed container in separate areas. The amount of the modifier added is 20% to 50% of the mass of the silica powder. The particles are heated to 110 to 130°C for 0.5 to 1 hour to complete the hydrophobic modification. The modified silica powder is obtained after vacuuming and cooling. The modifier is one or more of dimethyldiethylsilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane and aminoethylaminopropylmethyldimethoxysilane.

2. The photovoltaic module fast-curing anti-aging silicone sealant according to claim 1, characterized in that: The nano active calcium carbonate is stearic acid modified nano calcium carbonate.

3. The fast-curing anti-aging silicone sealant for photovoltaic modules according to claim 1, characterized in that: The water content of the hydrophobic fumed silica is less than 0.6%.

4. The photovoltaic module fast-curing anti-aging silicone sealant according to claim 1, characterized in that: The crosslinking agent is one or a combination of two of methyltributylanoxime silane, vinyltributylanoxime silane, and D-31 methyl mixed ketoxime crosslinking agent.

5. The photovoltaic module fast-curing anti-aging silicone sealant according to claim 1, characterized in that: The coupling agent is one or a combination of γ-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

6. A method for preparing the fast-curing anti-aging silicone sealant for photovoltaic modules according to any one of claims 1 to 5, characterized in that: The specific steps include: Step 1: Mix α,ω-dihydroxypolydimethylsiloxane, nano-activated calcium carbonate and modified silicon powder in a planetary mill, heat to 120℃~130℃ under vacuum, and stir to remove water for 3h~4h to obtain a base material with a moisture content of less than 0.01%; Step 2: Add hydrophobic fumed white carbon black to the base material cooled to room temperature, mix well, and stir under vacuum; Step 3: Add the crosslinking agent to the base material cooled to room temperature and mix well, stirring under vacuum; Step 4: Add the coupling agent and catalyst to the base material and stir under vacuum to obtain a fast-curing anti-aging silicone sealant for photovoltaic modules.

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