A quick deep curing weather-resistant silicone sealant and a preparation method thereof

Abstract

The present application relates to the technical field of silicone sealant, in particular to a kind of quick deep curing weather-resistant silicone sealant and preparation method thereof, according to weight parts, its preparation raw material at least includes: alkoxysilicone oil 85-120 parts, alkyl silicone oil 3-8 parts, modified polyether 8-15 parts, reinforcing filler 40-70 parts, porous filler 5-20 parts, extender 4-10 parts, antioxidant 0.01-0.05 parts, stabilizer 0.1-0.5 parts, crosslinking agent 1-5 parts, tackifier 0.1-1.0 parts, catalyst 0.1-1.0 parts, by optimizing sealant formula, on the basis of guaranteeing the basic mechanical properties and bonding properties of sealant, realize deep curing while improving the moisture resistance of product after complete curing, effectively improve production efficiency and the service life of photovoltaic module.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicone sealant, in particular to a rapid deep-curing weather-resistant silicone sealant and a preparation method thereof. BACKGROUND

[0002] Silicone adhesives are widely used in the bonding, sealing and protection of new energy industry related products due to their good adhesion, excellent weather resistance, high and low temperature resistance, UV resistance, low VOC and good compatibility with panel substrates. Currently, single-component deoxime type silicone sealant is mainly used for frame sealing in the photovoltaic industry. However, the deep curing of this product is slow, which affects the production efficiency during assembly. In addition, the product releases butanone oxime during curing. With the development of science and technology, the design and materials of new energy industry related products are changing rapidly, and the requirements for sealant have also changed. Therefore, it is imperative to develop new silicone adhesive technology to meet the application requirements of environmental protection, performance and construction process.

[0003] Currently, deep curing and adhesion performance are mainly achieved by modifying the crosslinking agent or adding curing / adhesion promoters. For example, Chinese Patent Application (Publication No. CN111704864B) discloses a silane modified polyether sealant and its preparation method and application. The low polymer formed by the hydrolysis crosslinking of a coupling agent is used as an adhesion promoter in combination with a specific catalyst to achieve deep curing. Chinese Patent Application (Publication No. CN115975591A) discloses a rapid deep-curing weather-resistant silicone sealant and its preparation method and application. The hydrolysis product of a phenyl-containing alkoxysilane crosslinking agent and a coupling agent is used as a crosslinking agent. The structure contains a large number of amine groups, acyloxy groups or epoxy hydrophilic groups, which are beneficial to the penetration of moisture from the surface to the interior, achieving rapid curing and deep curing. However, this may result in a decrease in the mechanical properties of the sealant and its resistance to humid heat environments. SUMMARY

[0004] To solve the above problems, the present application provides a sealant that does not release suspected carcinogen butanone oxime during curing. By optimizing the sealant formula, the product's moisture resistance after complete curing is improved while achieving deep curing, effectively improving production efficiency and the service life of photovoltaic modules, while ensuring the basic mechanical properties and adhesion performance of the sealant.

[0005] In one aspect, the present application provides a deep-curing weather-resistant silicone sealant. The preparation raw materials include, by weight: 85-120 parts of alkoxysilicone oil, 3-8 parts of alkyl silicone oil, 8-15 parts of modified polyether, 40-70 parts of reinforcing filler, 5-20 parts of porous filler, 4-10 parts of extender filler, 0.01-0.05 parts of antioxidant, 0.1-0.5 parts of stabilizer, 1-5 parts of crosslinking agent, 0.1-1.0 parts of tackifier, and 0.1-1.0 parts of catalyst.

[0006] As a preferred technical solution, the alkyl silicone oil is at least one of dimethyl silicone oil, methyl phenyl silicone oil, diethyl silicone oil, long-chain alkyl silicone oil with viscosity (25°C) of 50-5000 mPa.s. Preferably, the viscosity (25°C) of the alkyl silicone oil is 400 mPa.s-600 mPa.s. Preferably, the alkyl silicone oil is long-chain alkyl silicone oil with viscosity (25°C) of 500 mPa.s.

[0007] As a preferred technical solution, the alkyl silicone oil is at least one of dimethyl silicone oil, methyl phenyl silicone oil, diethyl silicone oil, long-chain alkyl silicone oil with viscosity (25°C) of 50-5000 mPa.s. Preferably, the viscosity (25°C) of the alkyl silicone oil is 400 mPa.s-600 mPa.s. Preferably, the alkyl silicone oil is long-chain alkyl silicone oil with viscosity (25°C) of 500 mPa.s.

[0008] As a preferred technical solution, the modified polyether is at least one of dimethoxysilane modified polyether, trimethoxysilane modified polyether, diethoxysilane modified polyether, triethoxysilane modified polyether with viscosity (25°C) of 50-1000 mPa.s. Preferably, the viscosity (25°C) of the modified polyether is 800-1000 mPa.s. Preferably, the modified polyether is dimethoxysilane modified polyether with viscosity (25°C) of 1000 mPa.s.

[0009] As a preferred technical solution, the reinforcing filler is one or more of lipophilic nano calcium carbonate, fumed white carbon black, precipitated white carbon black, nano aluminum hydroxide, nano titanium dioxide. Preferably, the reinforcing filler is a combination of nano calcium carbonate and fumed white carbon black, and the mass ratio of the nano calcium carbonate and fumed white carbon black is (10-15):1, preferably 12:1.

[0010] Preferably, the pore filler is one or more of modified diatomite, porous silica, and molecular sieve. Preferably, the pore filler is molecular sieve, which has a particle size of 2.0-4.0 um, a bulk density of 0.45-0.5, a pH value of 7-9, and a static water absorption rate of 22-28%. Preferably, the molecular sieve is 3A molecular sieve activated powder (2.0-4.0 um, bulk density 0.48, pH value: 7-9, static water absorption rate 26%) from Jiangxi Xitaokeli Technology Co., Ltd. Preferably, the porous silica has a particle size of 1.8-4.5 um, preferably Estone / SS002D (particle size 1.8-3 um) from Estone.

[0011] Preferably, the pore filler is added in an amount of 10-15% by weight based on the amount of alkoxyl silicone oil.

[0012] The present application aims to develop a sealant product that meets the requirements of environmental protection, performance, and construction process application. Specifically, alkoxyl-terminated polydimethylsiloxane is used as the base polymer, and vinyltrimethoxysilane oligomer and phenyltrimethoxysilane crosslinking agent are used to ensure the basic performance of the sealant product (meeting the requirements of GBT 29595-2013-Frame Sealant Table 1), while ensuring that the low-molecular released during the curing process of the one-component room temperature vulcanized silicone rubber is environmentally friendly, and does not release suspected carcinogen butanone oxime, improving the operating environment and reducing the impact of harmful substances on producers. The process is simple and can fully replace one-component deoxime type silicone adhesive in the frame sealing field of the photovoltaic industry.

[0013] Further, in view of the problem of slow deep curing of the frame sealing product in the photovoltaic industry, which seriously affects the production efficiency in the assembly process, the inventor finds that by introducing porous fillers such as modified diatomite, porous silica and molecular sieve into the one-component room temperature vulcanized silicone rubber system, and further controlling the addition amount of the porous fillers to be 10-15% of the weight of the alkylalkoxy silicone oil, the early curing speed of the glue layer is effectively improved, and the curing depth is greater than 1mm after 3h of curing, which can meet the rapid assembly demand in the frame sealing production process in the photovoltaic industry. The inventor analyzes the possible reason: under the addition amount, the neutral modified diatomite, molecular sieve or porous silica is dispersed in the one-component room temperature vulcanized silicone rubber system, and in the curing process, water molecules quickly reach the inside of the glue through the porous fillers, and at the same time, the low molecules in the curing process can quickly leave the glue, effectively accelerating the curing speed of the glue layer, and further improving the production efficiency. However, too much addition amount of the porous fillers will lead to the decline of the moisture resistance of the sealing glue, and affect the storage stability.

[0014] As a preferred technical solution, the extending filler is one or more of silicon powder, heavy calcium, calcium oxide, calcium silicate and mica powder. Preferably, the extending filler is mica powder, specifically flaky mica powder, and the particle size of the flaky mica powder is 5±2μm, preferably HY-TM6 of Shenzhen Haiyang Powder Technology Co., Ltd.

[0015] As a preferred technical solution, the addition amount of the long-chain alkyl silicone oil and the mica powder is 4-7% of the weight of the alkylalkoxy silicone oil, preferably 5%.

[0016] Based on the system of the present application, although the curing speed of the product is improved by introducing a certain amount of porous fillers to meet the packaging requirements, the moisture resistance of the product after complete curing is affected to a certain extent. The inventor finds that by simultaneously introducing long-chain alkyl silicone oil and flaky mica powder into the system, and further controlling the addition amount of the long-chain alkyl silicone oil and the mica powder to be 5% of the weight of the alkylalkoxy silicone oil, the problem of decline of the moisture resistance caused by the porous fillers is effectively solved without affecting the curing speed, and the resistance of the product to the humid heat environment is effectively improved to ensure the long-term effective airtight performance of the photovoltaic module, so that the photovoltaic module can run efficiently, safely and stably in harsh environments such as high temperature and high humidity, and the service life of the photovoltaic module is improved. The inventor analyzes the possible reason: after the product is completely cured, the long-chain alkyl silicone oil is introduced into the main chain of the silicone matrix, and the flaky mica powder is introduced, which realizes the blocking of moisture through different mechanisms. Since the one-component room temperature vulcanized silicone rubber provided by the present application needs to contact the water vapor in the air to crosslink, too high addition amount of the long-chain alkyl silicone oil and the flaky mica powder will block the contact between the silicone rubber and the water vapor to a certain extent, and affect the rapid and deep curing ability of the sealing glue.

[0017] As a preferred technical solution, the antioxidant is at least one of BASF antioxidant 1010, BASF antioxidant 1076, BASF antioxidant 225, BASF antioxidant 168, and BASF antioxidant 1790. Preferably, the antioxidant is a combination of BASF antioxidant 1010 and antioxidant 1790, and the mass ratio of the BASF antioxidant 1010 and the antioxidant 1790 is (1-2):1, preferably 2:1.

[0018] Based on the system of the present application, by using the BASF antioxidant 1010 and the antioxidant 1790 in a mass ratio of (1-2):1, the sealant provided is not prone to aging and yellowing in a high-temperature and high-humidity environment, further ensuring the service life of the product.

[0019] As a preferred technical solution, the stabilizer is at least one of trimethylmethoxysilane and (2-trimethylsilyl) ethyl acetate.

[0020] As a preferred technical solution, the cross-linking agent is one or more of methyltrimethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methylmethoxydipropionoxime silane, tetraethoxysilane, butyltrimethoxysilane, dodecyltrimethoxysilane, hexadecyltrimethoxysilane, and alkyltrimethoxysilane oligomer. Preferably, the cross-linking agent is a combination of vinyltrimethoxysilane oligomer and phenyltrimethoxysilane, and the mass ratio of the vinyltrimethoxysilane oligomer and the phenyltrimethoxysilane is 1:(3-5), preferably 1:4.

[0021] As a preferred technical solution, the tackifier is at least one of Wacker 1146, Jianghan JH-1231, and self-made tackifier A. Preferably, the tackifier is self-made tackifier A, and the preparation method of the self-made tackifier A is as follows: 10-60 parts by weight of an amino silane coupling agent and 20-30 parts by weight of an epoxy silane coupling agent are weighed into a three-necked flask, dry nitrogen is introduced, and stirring is started for 5-15 min, then boric acid is added, refluxing is carried out at 60-65°C for 0.5-1.5 h, then heating is stopped, butanediol and long-chain alkyl silane are added, and stirring is continued until it becomes transparent.

[0022] Preferably, the amino silane coupling agent is at least one of KH550, A1110, A1120, A1130, and KBM-602, and is preferably KH550.

[0023] ​​​Preferably, the epoxy silane coupling agent is at least one selected from the group consisting of γ-(2,3-epoxypropoxy)propyl trimethoxysilane, 3-(2,3-epoxypropoxypropyl)methyl diethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, preferably 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane.

[0024] Preferably, the long carbon chain alkyl silane has 10-20 carbon atoms in the long carbon chain alkyl group. Preferably, the long carbon chain alkyl silane is octadecyl trimethoxysilane.

[0025] Preferably, the preparation method of the self-made adhesion promoter A is as follows: 12.32 parts by weight of aminopropyl triethoxysilane (KH550) and 24.64 parts by weight of 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane are weighed into a 100 mL three-necked flask, dry nitrogen is introduced and stirring is started for 10 min, then 0.1 parts by weight of boric acid is added, heating is stopped after refluxing at 60-65°C for 1 hour, and 0.1 parts by weight of butanediol and 1 part by weight of octadecyl trimethoxysilane are added, and stirring is continued until the mixture becomes transparent.

[0026] The sealant provided by the application is actually applied to the frame sealing of a photovoltaic module. The photovoltaic module includes, from top to bottom, tempered glass, EVA, a cell sheet, EVA, a back plate, a sealant, an aluminum alloy frame, and a junction box. The bonding performance of the sealant also determines the service life of the photovoltaic module. Based on the large amount of reinforcing fillers, porous fillers, and extending fillers introduced in the system of the application, modified polyether and self-made adhesion promoter A are further introduced to improve the bonding performance of the sealant and the ability to resist high temperature and high humidity environments, so as to meet the actual application requirements of the frame sealing of the photovoltaic module. The inventor analyzes the reason as follows: the introduction of modified polyether and self-made adhesion promoter A improves the bonding force between the resin with amino reactivity and the inorganic metal surface and the plastic surface. At the same time, the long-chain fatty chain with excellent moisture barrier ability is introduced into the structure of the cured product, further improving the ability of the product to resist high temperature and high humidity environments and the service life of the photovoltaic module.

[0027] As a preferred technical solution, the catalyst is at least one selected from the group consisting of organic tin, organic zinc bismuth, titanate complex, and chelated tin; preferably, the catalyst is a combination of titanate complex and chelated tin, and the mass ratio of the titanate complex to the chelated tin is 1:3-5, preferably 1:4.

[0028] As a preferred technical solution, the addition amount of the modified polyether is 10%, the addition amount of the porous filler is 15%, the addition amount of the crosslinking agent is 2.5%, and the addition amount of the adhesion promoter is 1%, based on the weight parts of the alkyl silicone oil.

[0029] Based on the system of the application, titanium acid ester complex and chelated tin are used as catalysts to promote the hydrolysis cross-linking curing of the sealant system containing the above-mentioned amount of specific modified polyether, porous filler, cross-linking agent and tackifier, the penetration of water vapor into the deep layer of the glue is promoted through different mechanisms, the rapid deep curing of the sealant is realized, the uniformly dispersed single-component room temperature vulcanized silicone rubber is obtained, and the sealant product has excellent bonding performance on plastic and metal, which meets the actual application requirements of the frame sealing field in the photovoltaic industry, otherwise the bonding performance and curing efficiency of the sealant product cannot be ensured at the same time.

[0030] Another aspect of the application provides a preparation method of a deep-cured weather-resistant silicone sealant, at least comprising the following steps:

[0031] (1) According to the weight parts, alkoxysilicone oil, alkyl silicone oil, modified polyether, porous filler, reinforcing filler, extending filler, antioxidant are added into the reaction kettle, and high-speed vacuum stirring is carried out under heating.

[0032] (2) After cooling to 30-40℃, the cross-linking agent is added and vacuum stirred, and then the tackifier, catalyst and stabilizer are added after drying and unloading pressure with nitrogen, and vacuum stirring is carried out, and the material temperature is controlled at 45-50℃.

[0033] As a preferred technical solution, the high-speed vacuum stirring under heating is specifically at a temperature of 110-130℃ and a stirring time of 2-4h.

[0034] As a preferred technical solution, the vacuum stirring time in step (2) is 20-40min.

[0035] Beneficial effects

[0036] 1. The application provides a rapid deep-cured weather-resistant silicone sealant and a preparation method thereof, which realizes deep curing while improving the moisture resistance of the product after complete curing by optimizing the sealant formula on the basis of ensuring the basic mechanical properties and bonding performance of the sealant, and effectively improves the production efficiency and service life of photovoltaic modules.

[0037] 2. The application introduces porous fillers such as modified diatomite, porous silica and molecular sieve into the single-component room temperature vulcanized silicone rubber system, and further controls the addition amount of the porous filler to be 10-15% of the weight of the alkoxysilicone oil, which effectively improves the early curing speed of the glue layer, and the curing depth is >1mm after 3h of curing, which can meet the rapid assembly requirements in the production process of the frame sealing of the photovoltaic industry.

[0038] 3. Based on the system of the present application, by simultaneously introducing long-chain alkyl silicone oil and flaky mica powder in the system, the addition amount of long-chain alkyl silicone oil and mica powder is controlled to be 5% of the weight of the alkoxysilicone oil, which does not affect the curing speed, effectively solves the problem of moisture resistance performance decline caused by porous filler, effectively improves the resistance of the product to the humid heat environment, ensures the long-term effective airtight performance of the photovoltaic module, and enables the photovoltaic module to operate efficiently, safely and stably in harsh environments such as high temperature and high humidity, and prolongs the service life of the photovoltaic module.

[0039] 4. Based on the system of the present application, by introducing modified polyether and self-made tackifier A, the adhesion performance and the ability to resist high temperature and high humidity environment of the sealant are improved, and the practical application requirements of the frame sealing in the photovoltaic module are met.

[0040] 5. The sealant provided by the present application is based on the system of the present application, and titanium ester complex and chelated tin are used as catalysts to promote the hydrolysis cross-linking curing of the sealant system containing the above-mentioned amount of specific modified polyether, porous filler, cross-linking agent and tackifier. Different mechanisms promote the penetration of water vapor into the deep layer of the glue, realize the rapid deep curing of the sealant, and obtain a dispersed and uniform single-component room temperature vulcanized silicone rubber. At the same time, the sealant product has excellent adhesion performance to plastics and metals, and meets the practical application requirements of the frame sealing field in the photovoltaic industry. DETAILED DESCRIPTION

[0041] Embodiments 1-6 of the present application provide a kind of quick deep curing weather-resistant silicone sealant, and its preparation raw material is referred to table 1 by weight parts.

[0042] Table 1,

[0043]

[0044]

[0045] Note: the blank in the table is 0.

[0046] The preparation method of the self-made tackifier A is as follows: 12.32 parts by weight of aminopropyl triethoxysilane (KH550) and 24.64 parts by weight of 2-(3,4-epoxy cyclohexyl) ethyl trimethoxysilane are weighed into a 100 mL three-necked flask, dry nitrogen is introduced and stirring is started for 10 min, then 0.1 parts by weight of boric acid is added, the refluxing is stopped at 65 DEG C for 1 hour, then 0.1 parts by weight of butanediol and 1 parts by weight of octadecyl trimethoxysilane are added, and the stirring is continued until the mixture becomes transparent.

[0047] Embodiments 1-6 of the present application further provide a preparation method of the quick deep curing weather-resistant silicone sealant, which comprises the following steps:

[0048] (1) According to parts by weight, alkoxysilicone oil, alkyl silicone oil, modified polyether, porous filler, reinforcing filler, extending filler, antioxidant are added into a reaction kettle, temperature is raised, and high-speed vacuum stirring is carried out;

[0049] (2) After temperature is reduced to 40 DEG C, crosslinking agent is added, vacuum stirring is carried out, after drying nitrogen is unloaded, tackifier, catalyst and stabilizer are added, vacuum stirring is carried out, and material temperature is controlled at 50 DEG C.

[0050] The temperature of the high-speed vacuum stirring is 120 DEG C, and the stirring time is 3h.

[0051] The vacuum stirring time in the step (2) is 30 min.

[0052] Performance test method

[0053] According to national standards GB T528-2009, GBT 7124-2008 and GBT 29595-2013, the following performances of the sealant provided by the examples and the comparative examples of the application are tested, and the test results are shown in Tables 2 and 3.

[0054] Table 2,

[0055]

[0056]

[0057] Table 3,

[0058]

Claims

1. A fast-curing, deep-curing, weather-resistant silicone sealant, characterized in that, The raw materials for its preparation, by weight, include at least: 85-120 parts alkoxy silicone oil, 3-8 parts alkyl silicone oil, 8-15 parts modified polyether, 40-70 parts reinforcing filler, 5-20 parts porous filler, 4-10 parts expander filler, 0.01-0.05 parts antioxidant, 0.1-0.5 parts stabilizer, 1-5 parts crosslinking agent, 0.1-1.0 parts tackifier, and 0.1-1.0 parts or 2.5 parts catalyst; wherein the alkyl silicone oil has a viscosity of 400-600 mPa•s at 25°C. The product is a long-chain alkyl silicone oil; the modified polyether is at least one of dimethoxysilane-modified polyether, trimethoxysilane-modified polyether, diethoxysilane-modified polyether, and triethoxysilane-modified polyether, with a viscosity of 800-1000 mPa•s at 25°C; the porous filler is one or more of modified diatomaceous earth, porous silica, and molecular sieve, wherein the molecular sieve has a particle size of 2.0-4.0 μm, a bulk density of 0.45-0.5, a pH value of 7-9, and a static water absorption rate of 22-28%. The porous silica has a particle size of 1.8-4.5 μm; the modified diatomaceous earth is coated with silane with a fineness of 2-5 μm and a pH of 7-9; the thickener is a self-made thickener A, which is prepared by weighing 10-60 parts by weight of amino-based silane coupling agent and 20-30 parts by weight of epoxy-based silane coupling agent into a three-necked flask, introducing dry nitrogen gas and stirring for 5-15 minutes, then adding boric acid, and refluxing at 60℃-65℃ for 0.5-1.5 hours. Stop heating and add butanediol and long-chain alkylsilane, stirring until transparent; the incremental filler is flake mica powder with a particle size of 5±2μm; the crosslinking agent is a combination of vinyltrimethoxysilane oligomer and phenyltrimethoxysilane, with a mass ratio of vinyltrimethoxysilane oligomer to phenyltrimethoxysilane of 1:(3-5); the catalyst is a combination of titanate complex and chelated tin, with a mass ratio of titanate complex to chelated tin of 1:(3-5).

2. The rapid-curing, deep-curing, weather-resistant silicone sealant according to claim 1, characterized in that, The alkoxy silicone oil is at least one of trimethoxy-terminated 107 silicone oil, dimethoxy-terminated 107 silicone oil, and diethoxy-terminated 107 silicone oil with a viscosity of 500 mPa•s-80000 mPa•s.

3. The rapid-curing, deep-curing, weather-resistant silicone sealant according to claim 1, characterized in that, The reinforcing filler is one or more of the following: oleophilic nano-calcium carbonate, fumed silica, precipitated silica, nano-aluminum hydroxide, and nano-titanium dioxide.

4. A method for preparing a rapid-curing, deep-curing, weather-resistant silicone sealant according to any one of claims 1-3, characterized in that, At least the following steps are included: (1) Add alkoxy silicone oil, alkyl silicone oil, modified polyether, reinforcing filler, porous filler, additive filler and antioxidant to the reactor according to the weight parts, and heat and stir at high speed under vacuum. (2) After cooling to 30-40℃, add crosslinking agent and stir under vacuum. After drying and depressurizing nitrogen, add thickener, catalyst and stabilizer and stir under vacuum. Control the material temperature at 45-50℃.

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