Heat-conducting water-blocking sealant, preparation method thereof and photovoltaic module

Abstract

The invention provides a heat-conducting water-blocking sealant, a preparation method thereof and a photovoltaic module. The heat-conducting and water-blocking sealant is prepared from the following raw materials in parts by mass: 50 to 100 parts of methyl vinyl siloxane, 50 to 100 parts of lignin, 10 to 50 parts of diamond particles and / or diamond alloy particles, 0.5 to 10 parts of a first cross-linking agent, 0.5 to 10 parts of a second cross-linking agent, 0.5 to 5 parts of a coupling agent and 0.05 to 1 part of a catalyst, wherein the first cross-linking agent is prepared from one or more of dicumyl peroxide, benzoyl peroxide, toluene diisocynate and hexamethylene diisocyanate; the second cross-linking agent comprises polymethylhydrosiloxane. The heat-conducting and water-blocking sealant disclosed by the invention has relatively good heat-conducting property, water-blocking property and electrical insulation property.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic technology, in particular to a heat-conducting and water-resistant sealant, a preparation method thereof and a photovoltaic module. BACKGROUND

[0002] A junction box is usually arranged on a photovoltaic module to centrally connect the battery units and transmit the current generated by the module to external equipment. When the photovoltaic module is operated outdoors, the junction box is the main heat source of the photovoltaic module and is often the dry way of the current. The junction box often reaches a temperature of 80-90℃. The junction box is easily damaged when operated at high temperatures for a long time. In addition, the junction box is equivalent to the connection site of the battery unit and the external equipment. When the photovoltaic module is used outdoors, water vapor easily penetrates into the junction box, causing the components to be damp or short-circuited, affecting the stability and reliability of the module.

[0003] Therefore, a protective sealant needs to be used to seal and protect the junction box to play the roles of sealing, waterproofing and fixing. However, the heat-conducting performance or water resistance of the conventional protective sealant is not good, and it cannot well conduct the heat at the junction box to dissipate heat in time while playing a good waterproofing role.

[0004] Therefore, the conventional sealant for the junction box still needs to be further improved. SUMMARY

[0005] Therefore, the present application provides a heat-conducting and water-resistant sealant, a preparation method thereof and an application. The heat-conducting and water-resistant sealant has good heat-conducting performance, water resistance and electrical insulation performance.

[0006] The technical solutions provided by the present application are as follows:

[0007] According to a first aspect of the present application, a heat-conducting and water-resistant sealant is provided, which comprises the following component raw materials in parts by mass:

[0008] Methylvinylsiloxane 50-100 parts;

[0009] Lignin 50-100 parts;

[0010] Diamond particles and / or diamond alloy particles 10-50 parts;

[0011] First crosslinking agent 0.5-10 parts;

[0012] Second crosslinking agent 0.5-10 parts;

[0013] Coupling agent 0.5-5 parts;

[0014] Catalyst 0.05-1 parts;

[0015] The first cross-linking agent comprises one or more of dicumyl peroxide, benzoyl peroxide, toluene diisocyanate, and hexamethylene diisocyanate; and the second cross-linking agent comprises polymethylhydrogenosiloxane.

[0016] The heat-conducting and water-resisting sealant described above takes methyl vinyl siloxane as a main base material, and the methyl vinyl siloxane rubber formed after cross-linking has good water-resisting performance and is not easy to foam and has good high-temperature compression deformation resistance; both lignin and methyl vinyl siloxane are polar molecules, the hydroxyl groups in lignin can be bonded with the siloxane bonds in methyl vinyl siloxane, so that the two can be well combined; at the same time, lignin itself has a three-dimensional network structure, which can form a kind of steric hindrance around the diamond and / or diamond alloy particles, preventing the agglomeration between the diamond and / or diamond alloy particles, so that the diamond and / or diamond alloy can be uniformly dispersed in the system. In addition, lignin can also be used as a reinforcing filler, which can not only enhance the mechanical properties of the sealant and reduce the cost, but also endow the sealant with excellent water-resisting performance, flame-retardant performance, ultraviolet resistance and anti-aging performance. Diamond and / or diamond alloy as a high-thermal-conductivity filler has high thermal conductivity and good chemical stability, and can maintain excellent thermal conductivity in a high-temperature environment, which can improve the thermal conductivity of the sealant and has high electrical insulation performance. The first cross-linking agent can promote the formation of a cross-linked network of lignin and methyl vinyl siloxane, and improve the bonding strength and stability of the sealant. The second cross-linking agent can form a cross-linked network with methyl vinyl siloxane, and promote the formation of a stable structure of diamond and / or diamond alloy and methyl vinyl siloxane.

[0017] By using methyl vinyl siloxane, lignin, diamond and / or diamond alloy, first cross-linking agent, second cross-linking agent, coupling agent and catalyst in specific mass fractions for compounding, the heat-conducting and water-resisting sealant obtained can have excellent thermal conductivity and water-resisting performance, and has good electrical insulation performance; when used as a sealant for a junction box of a photovoltaic module, it can effectively improve the stability and reliability of the module.

[0018] In any embodiment, the mole fraction of vinyl siloxane in the methyl vinyl siloxane is 0.001% to 0.004%. Further optionally, it is 0.003%.

[0019] In any embodiment, the first cross-linking agent comprises dicumyl peroxide and toluene diisocyanate, and the mass ratio of the dicumyl peroxide to the toluene diisocyanate is 1:1 to 3.

[0020] In any embodiment, the diamond alloy particles comprise one or more of copper diamond alloy particles and aluminum diamond alloy particles.

[0021] In any of the embodiments, the particle size of the diamond particles and / or the diamond alloy particles is 5-300 μm. Further optionally, the particle size is 40-60 μm.

[0022] In any of the embodiments, the lignin comprises one or more of alkali lignin, lignin sulfonate, organic solvent lignin, and ionic liquid lignin. Further optionally, the lignin is alkali lignin.

[0023] In any of the embodiments, the thermally-conductive and water-resistant sealant further comprises 0.5-10 parts by mass of a diamond surface modifier, the diamond surface modifier comprising one or more of 3-mercaptopropyltrimethoxysilane and γ-aminopropyltriethoxysilane. Further optionally, the diamond surface modifier is 3-mercaptopropyltrimethoxysilane.

[0024] In any of the embodiments, the coupling agent comprises one or more of a silane coupling agent, a titanate coupling agent, a phosphate coupling agent, and a borate coupling agent.

[0025] In any of the embodiments, the coupling agent comprises silane coupling agent KH550 and silane coupling agent KH560, and the mass ratio of the silane coupling agent KH550 to the silane coupling agent KH560 is 1-4:1.

[0026] In any of the embodiments, the catalyst comprises one or more of triethylamine, N,N-dimethylethanolamine, N,N-dimethylbenzylamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N',N''-pentamethyldiethylenetriamine, bis-(2-dimethylaminoethyl) ether, 1,4-diazabicyclo[2.2.2]octane, and tetramethylammonium hydroxide.

[0027] In any of the embodiments, the catalyst comprises triethylamine and N,N-dimethylethanolamine, and the mass ratio of the triethylamine to the N,N-dimethylethanolamine is 1:1-2.

[0028] According to a second aspect of the present application, there is provided a method for preparing the thermally-conductive and water-resistant sealant of the first aspect of the present application, comprising the following steps:

[0029] The methylvinylsiloxane, the lignin, the first cross-linking agent, and the catalyst are stirred and reacted at 120-140 °C for 2.5-4 h to obtain a base material;

[0030] The diamond particles and / or the diamond alloy particles, the second cross-linking agent, the coupling agent, and the base material are mixed and reacted to obtain the thermally-conductive and water-resistant sealant.

[0031] According to a third aspect of the present application, a photovoltaic module is provided, comprising the heat-conducting and water-resistant sealant of the first aspect of the present application as a sealant for a junction box in the photovoltaic module. DETAILED DESCRIPTION

[0032] In order to make the above objectives, features and advantages of the present application more clear and easy to understand, the specific embodiments of the present application are described in detail. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be implemented in many different ways other than those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, and therefore the present application is not limited to the specific embodiments disclosed below.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Unless otherwise specifically defined, various materials, reagents, instruments and equipment used in the present application are commercially available or can be prepared according to the prior art.

[0034] The conventional sealant for the junction box of the photovoltaic module is mostly silicone sealant, which has good temperature resistance and weather resistance. However, the silicone sealant is composed of linear polysiloxane, in which the Si-O-Si bond is long and the bond angle is large, and the cohesive energy after cross-linking is not high, resulting in weak water vapor barrier ability of the sealant. The penetration of water vapor into the inside of the junction box can easily cause the components to be damp or short-circuited, affecting the stability and reliability of the module. In addition, the junction box is the main heat source on the photovoltaic module, and the junction box is easily damaged when operating at high temperature for a long time, and therefore the sealant is required to have good heat conduction performance to improve the heat dissipation performance at the junction box.

[0035] Based on this, some embodiments of the present application provide a heat-conducting and water-resistant sealant, which comprises the following raw materials in parts by mass: methylvinylsiloxane 50-100 parts, lignin 50-100 parts, diamond particles and / or diamond alloy particles 50-150 parts, first cross-linking agent 0.5-10 parts, second cross-linking agent 0.5-10 parts, coupling agent 0.5-5 parts, and catalyst 0.05-1 part. The first cross-linking agent includes one or more of dicumyl peroxide (DCP), benzoyl peroxide (BPO), toluene diisocyanate (TDI), and hexamethylene diisocyanate (HDI); and the second cross-linking agent includes polymethylhydrogenosiloxane.

[0036] The heat-conducting and water-resisting sealant described above in the present application is compounded by using methyl vinyl siloxane, lignin, diamond particles and / or diamond alloy particles, a first cross-linking agent, a second cross-linking agent, a coupling agent and a catalyst in specific mass fractions, and has excellent heat-conducting and water-resisting properties and good electrical insulation property. When used as a sealant for a junction box of a photovoltaic module, it can effectively improve the stability and reliability of the module.

[0037] Specifically, methyl vinyl siloxane is used as a base material, and the methyl vinyl siloxane rubber formed after cross-linking has good water-resisting property and is not prone to foaming and has good high-temperature compression resistance.

[0038] Lignin and methyl vinyl siloxane are both polar molecules, and the hydroxyl groups in lignin can be bonded to the siloxane bonds in methyl vinyl siloxane, so that the two can be well combined. At the same time, lignin itself has a three-dimensional network structure, which can form a steric hindrance around the diamond particles and / or diamond alloy particles, preventing the agglomeration of the diamond particles and / or diamond alloy particles, so that the diamond particles and / or diamond alloy particles are uniformly dispersed in the system.

[0039] By adding lignin as a reinforcing filler, the mechanical properties of the sealant can be enhanced, the cost can be reduced, and the sealant can be endowed with excellent water-resisting property, flame-retardant property, ultraviolet resistance and anti-aging property. Diamond particles and / or diamond alloy particles as high-thermal-conductivity fillers have high thermal conductivity and good chemical stability, and can maintain excellent heat-conducting property in high-temperature environment, which can improve the heat-conducting property of the sealant and has high electrical insulation property.

[0040] The first cross-linking agent can promote the formation of a cross-linked network of lignin and methyl vinyl siloxane, and improve the adhesion strength and stability of the sealant. The second cross-linking agent can form a cross-linked network with methyl vinyl siloxane, and promote the formation of a stable structure of diamond particles and / or diamond alloy particles and methyl vinyl siloxane.

[0041] It should be noted that the heat-conducting and water-resisting sealant includes diamond particles and / or diamond alloy particles, which means that the heat-conducting and water-resisting sealant can include only diamond particles, or only diamond alloy particles, or both diamond particles and diamond alloy particles.

[0042] In any embodiment, the mole fraction of the vinyl siloxane in the methyl vinyl siloxane is 0.001% to 0.004%. Further optionally, 0.003%. The methyl vinyl siloxane is copolymerized from dimethyl siloxane monomers and a small amount of vinyl siloxane monomers. By introducing the above amount of vinyl siloxane, the methyl vinyl siloxane can be endowed with better vulcanization performance, heat aging resistance and high temperature compression deformation resistance. When the mole fraction of the vinyl siloxane in the methyl vinyl siloxane is too large, the heat aging resistance of the methyl vinyl siloxane will decrease.

[0043] The mole fraction of a structural unit or a monomer unit in the copolymer refers to the proportion of the amount of substance of the structural unit or the monomer unit to the total amount of substance of all structural units in the copolymer. For example, for a binary copolymer composed of monomer A and monomer B, the mole fraction of monomer A is n A / (n A +n B ) x 100%; wherein n A and n B represent the amount of substance of monomer A and monomer B, respectively.

[0044] It can be understood that the mole fraction of the vinyl siloxane in the methyl vinyl siloxane can be 0.001%, 0.0012%, 0.0015%, 0.0018%, 0.002%, 0.0022%, 0.0025%, 0.0028%, 0.003%, 0.0035%, 0.0038%, 0.004%, and any value within the range formed by any two of the above values.

[0045] In any embodiment, the first cross-linking agent includes dicumyl peroxide and toluene diisocyanate; wherein the mass ratio of dicumyl peroxide and toluene diisocyanate is 1:1 to 3. Using the above ratio of dicumyl peroxide and toluene diisocyanate as the first cross-linking agent is more conducive to promoting the formation of a cross-linked network of lignin and methyl vinyl siloxane, and is conducive to improving the bonding strength and stability of the sealant.

[0046] The mass ratio of dicumyl peroxide and toluene diisocyanate can be 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 1:2.2, 1:2.5, 1:2.8, 1:3, and any value within the range formed by any two of the above values.

[0047] In any embodiment, the diamond alloy particles include one or more of copper diamond alloy particles and aluminum diamond alloy particles. Preferably, diamond particles are used as the heat conductive filler. Diamond particles and diamond alloy particles have a thermal conductivity of up to 1000 W / m.k ~ 2300 W / m.k, which is an excellent heat conductive material, and have high electrical insulation, which is beneficial to improve the heat conductive performance and electrical insulation performance of the sealant when added to the sealant as a heat conductive filler.

[0048] Further, the particle size of the diamond particles and / or the diamond alloy particles is 5 μm ~ 300 μm. Further optionally, the particle size is 40 μm ~ 60 μm. Understandably, the particle size of the diamond particles and / or the diamond alloy particles can be 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, 220 μm, 240 μm, 260 μm, 280 μm, 300 μm, and any value within the range formed by any two of the above values.

[0049] In any embodiment, the lignin includes one or more of alkali lignin, lignin sulfonate, organic solvent lignin, and ionic liquid lignin. Further optionally, the lignin is alkali lignin. The alkali lignin is obtained by dissolving lignin from plant fiber raw materials through alkali cooking, and then separating and purifying the lignin. The lignin sulfonate is obtained by concentrating, separating, and drying lignin sulfonate solution produced in the sulfite pulping process. The organic solvent lignin is obtained by extracting plant fiber raw materials with an organic solvent (such as ethanol, acetone, etc.) under certain conditions, dissolving the lignin in the organic solvent, and then removing the solvent by distillation. The ionic liquid lignin is obtained by treating plant fiber raw materials with ionic liquid as a solvent, dissolving the lignin in the ionic liquid, and then separating the lignin by adding a precipitant or using extraction.

[0050] Further, the lignin is alkali lignin. The alkali lignin has properties close to natural lignin, and has a large number of active groups such as hydroxyl groups on the surface, which has good reactivity and is beneficial to better combine with the methyl vinyl siloxane and improve the performance of the sealant.

[0051] In any embodiment, the heat-conducting and water-resisting sealant further comprises 0.5-10 parts by mass of a diamond surface modifier, the diamond surface modifier comprising one or more of 3-mercaptopropyltrimethoxysilane and γ-aminopropyltriethoxysilane. The surface modification of the diamond particles and diamond alloy particles by the diamond surface modifier described above is conducive to improving the compatibility between the diamond particles and diamond alloy particles and the rubber matrix, improving the interfacial bonding force, and further improving the heat-conducting performance of the sealant. In some specific examples, the diamond surface modifier is 3-mercaptopropyltrimethoxysilane.

[0052] It can be understood that the mass fraction of the diamond surface modifier in the heat-conducting and water-resisting sealant can be 0.5 parts, 0.8 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, and any value within the range formed by any two of the above values.

[0053] In any embodiment, the coupling agent comprises one or more of a silane coupling agent, a titanate coupling agent, a phosphate coupling agent, and a borate coupling agent.

[0054] In some specific examples, the coupling agent is silane coupling agent KH550 and silane coupling agent KH560; and the mass ratio of the silane coupling agent KH550 and the silane coupling agent KH560 is 1-4:1. It can be understood that the mass ratio of the silane coupling agent KH550 and the silane coupling agent KH560 can be 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, 2.8:1, 3:1, 3.2:1, 3.5:1, 3.8:1, 4:1, and any ratio within the range formed by any two of the above ratios.

[0055] In any embodiment, the catalyst comprises one or more of triethylamine, N,N-dimethylethanolamine, N,N-dimethylbenzylamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N',N''-pentamethyldiethylenetriamine, bis-(2-dimethylaminoethyl) ether, 1,4-diazabicyclo[2.2.2]octane, and tetramethylammonium hydroxide.

[0056] In some specific examples, the catalyst is triethylamine and N,N-dimethylethanolamine; and the mass ratio of the triethylamine and the N,N-dimethylethanolamine is 1:1-2. It can be understood that the mass ratio of the triethylamine and the N,N-dimethylethanolamine can be 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, and any ratio within the range formed by any two of the above ratios.

[0057] According to a second aspect of the present application, a preparation method of the heat-conducting and water-resistant sealant of the first aspect of the present application is provided, and the preparation method comprises the following steps: mixing methyl vinyl siloxane, lignin, a first cross-linking agent and a catalyst according to mass fractions, stirring and reacting at 120-140 DEG C for 2.5-4 hours to obtain a base material; mixing and reacting diamond particles and / or diamond alloy particles, a second cross-linking agent and a coupling agent with the base material to obtain the heat-conducting and water-resistant sealant.

[0058] In this way, the methyl vinyl siloxane is first reacted with the lignin in the presence of the first cross-linking agent and the catalyst to enable the methyl vinyl siloxane to perform cross-linking reaction and enable the hydroxyl groups in the lignin to bond with the siloxane bonds in the methyl vinyl siloxane to form the base material; then the diamond particles and / or diamond alloy particles are reacted with the base material in the presence of the second cross-linking agent and the coupling agent to obtain the heat-conducting and water-resistant sealant with good heat-conducting performance, water resistance and electrical insulation performance.

[0059] In some specific examples, the heat-conducting and water-resistant sealant is prepared by the following method: mixing methyl vinyl siloxane, lignin, a first cross-linking agent and a catalyst according to mass fractions, vacuumizing to -0.10-0.07 MPa, stirring and mixing for 30-60 minutes, then stirring and reacting at 120-140 DEG C for 2.5-4 hours to obtain a first base material; putting diamond particles and / or diamond alloy particles and a diamond surface modifier into a vacuum kneader, stirring and reacting at -0.10-0.07 MPa and 120-140 DEG C for 2.5-4 hours to obtain a second base material; transferring the first base material and the second base material prepared above into a planetary dynamic mixer, adding a second cross-linking agent, vacuumizing to -0.10-0.07 MPa, stirring and mixing for 30-60 minutes, filling nitrogen to release the vacuum, then adding a coupling agent, vacuumizing to -0.10-0.07 MPa, stirring again for 30-60 minutes, filling nitrogen to release the vacuum, discharging the material after uniform mixing to obtain the heat-conducting and water-resistant sealant.

[0060] According to a third aspect of the present application, a photovoltaic module is provided, and the photovoltaic module comprises the heat-conducting and water-resistant sealant of the first aspect of the present application as a sealant for a junction box of the photovoltaic module. By using the heat-conducting and water-resistant sealant of the present application as the sealant for the junction box of the photovoltaic module, the sealant has good heat-conducting performance, water resistance and electrical insulation performance, and can enable the photovoltaic module to have good stability and reliability.

[0061] The present application will be further described below in combination with specific examples and comparative examples, but should not be understood as limiting the scope of protection of the present application.

[0062] Example 1:

[0063] (1) Preparation of the first base material

[0064] Methyl vinyl siloxane 100 parts (vinyl siloxane mole fraction 0.003%), alkali lignin 50 parts, first crosslinking agent 1.0 part (DCP:TDI=1:1), catalyst 0.1 part (triethylamine:N,N-dimethyl ethanolamine=1:1) were mixed by mass parts under the condition of -0.10 MPa and 130°C for 3.5 hours, and the first base material was obtained after cooling.

[0065] (2) Preparation of the second base material

[0066] Diamond particles 10 parts (average particle size 50 μm) and diamond surface modifier 3-mercaptopropyl trimethoxysilane 2.0 parts were put into a vacuum kneader, and the second base material was obtained after mixing under the condition of -0.10 MPa and 130°C for 3.5 hours and cooling.

[0067] (3) Preparation of the heat-conducting and water-resistant sealant

[0068] The first base material and the second base material were transferred into a planetary dynamic mixer, and second crosslinking agent polymethyl hydrogen siloxane 1.0 part was added. Vacuum was extracted to -0.10 MPa, and the mixture was stirred for 45 minutes. Nitrogen was filled to release the vacuum. Coupling agent (KH550:KH560=1:1) 2.0 parts was added, vacuum was extracted to -0.10 MPa, and the mixture was stirred for 45 minutes again. Nitrogen was filled to release the vacuum. After the material was uniformly mixed, the heat-conducting and water-resistant sealant was obtained.

[0069] Example 2:

[0070] This example is basically the same as Example 1, except that the amount of diamond particles in step (2) is 20 parts, and the amount of polymethyl hydrogen siloxane in step (3) is 2.0 parts.

[0071] Example 3:

[0072] This example is basically the same as Example 1, except that the amount of diamond particles in step (2) is 30 parts, the amount of 3-mercaptopropyl trimethoxysilane is 3.0 parts, and the amount of polymethyl hydrogen siloxane in step (3) is 3.0 parts.

[0073] Example 4:

[0074] This example is basically the same as Example 1, except that the amount of diamond particles in step (2) is 40 parts, the amount of 3-mercaptopropyl trimethoxysilane is 4.0 parts, and the amount of polymethyl hydrogen siloxane in step (3) is 4.0 parts.

[0075] Example 5:

[0076] This example is basically the same as example 1, the difference is that: in step (1), the amount of alkali lignin is 70 parts, the amount of the first crosslinking agent is 1.5 parts (DCP:TDI=1:2), the amount of the catalyst is 0.2 parts; in step (2), the amount of diamond particles is 30 parts, the amount of 3-mercaptopropyl trimethoxysilane is 3.0 parts; in step (3), the amount of polymethyl hydrogen siloxane is 3.0 parts.

[0077] Example 6:

[0078] This example is basically the same as example 1, the difference is that: in step (1), the amount of alkali lignin is 100 parts, the amount of the first crosslinking agent is 2 parts (DCP:TDI=1:2), the amount of the catalyst is 0.3 parts (triethylamine:N,N-dimethylethanolamine=1:2); in step (2), the amount of diamond particles is 30 parts, the amount of 3-mercaptopropyl trimethoxysilane is 3.0 parts; in step (3), the amount of polymethyl hydrogen siloxane is 3.0 parts.

[0079] Comparative Example 1:

[0080] This comparative example is basically the same as example 1, the difference is that: silicon nitride particles are used instead of diamond particles in step (2) as the heat-conducting filler.

[0081] Comparative Example 2:

[0082] This comparative example is basically the same as example 1, the difference is that: aluminum oxide particles are used instead of diamond particles in step (2) as the heat-conducting filler.

[0083] Comparative Example 3:

[0084] This comparative example is basically the same as example 1, the difference is that: no alkali lignin is added in step (1).

[0085] Test method:

[0086] (1) Volume resistivity test

[0087] The volume resistivity of the sealant is tested according to the standard GB / T 1410-2006.

[0088] (2) Thermal conductivity test

[0089] The sealant is made into a block or sheet sample of a certain size, and the length and width of the sample are required to be much larger than the diameter of the hot-wire probe, and the thickness is between 10mm and 50mm. The hot-wire probe is uniformly buried in the sample, ensuring that the hot-wire is at the center position of the sample and parallel to the upper and lower surfaces of the sample.

[0090] After connecting the heating power supply, temperature measurement system and data acquisition and processing system, turn on the heating power supply to apply a constant heating power to the hot wire. At the same time, the temperature change around the hot wire is monitored in real time through the temperature measurement system, and the temperature data at different times is collected. According to the collected temperature-time data, the temperature-time curve is fitted by using the special software of the hot wire method or the related calculation formula, and then the thermal conductivity of the sealant is calculated.

[0091] (3) Water permeability test

[0092] The water permeability of the sealant is tested according to the standard GB / T 26253-2010.

[0093] The performance of the sealant of each of the above examples and comparative examples is tested, and the performance test results are shown in Table 1.

[0094] Table 1

[0095]

[0096] As shown in Table 1, the thermal conductive and water-resistant sealant of each of the examples has a high volume resistivity, a high thermal conductivity and a small water permeability, indicating that the sealant has good electrical insulation performance, thermal conductivity and water resistance.

[0097] In Examples 1-4, as the content of diamond particles increases, the thermal conductive network formed by diamond particles and methylvinylsiloxane increases, and the thermal conductivity of the thermal conductive and water-resistant sealant gradually increases. Since the volume resistivity of diamond particles can reach 10 15 Ω / cm~10 17 Ω / cm, as the content of diamond particles increases, the volume resistivity of the thermal conductive and water-resistant sealant also increases to a certain extent. In Examples 5-6, as the content of lignin increases, the water permeability of the thermal conductive and water-resistant sealant decreases significantly, and the thermal conductivity and volume resistivity are also high.

[0098] In Comparative Examples 1 and 2, silicon nitride particles and aluminum oxide particles are respectively used instead of diamond particles as the thermal conductive filler, and the thermal conductivity of the sealant decreases significantly, and the volume resistivity also decreases, indicating that the thermal conductivity and electrical insulation performance of the sealant decrease. In Comparative Example 3, no lignin is added, the water permeability of the sealant increases greatly, and the thermal conductivity and volume resistivity also decrease significantly.

[0099] In addition, the extrusion, surface drying time and curing depth of the sealant of each of the examples have no great difference compared with Comparative Examples 1-2; it is indicated that the addition of diamond and lignin almost does not affect the extrusion, surface drying time and curing depth of the thermal conductive and water-resistant sealant.

[0100] Any combination of the technical features in the above-described embodiments can be made, and for the sake of brevity, not all possible combinations are described, however, it is to be understood that the application encompasses all such possible combinations.

[0101] The above-described embodiments only express several implementation manners of the application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the application. It should be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the application, and these all belong to the protection scope of the application. Therefore, the protection scope of the application should be subject to the appended claims, and the description can be used to explain the content of the claims.

Claims

1. A heat-conducting, water-resistant sealant, characterized by, The raw materials include the following by mass fraction: Methyl vinyl siloxane 50-100 parts; Lignin 50-100 parts; Diamond particles and / or diamond alloy particles 10-50 parts; First crosslinking agent 0.5-10 parts; Second crosslinking agent 0.5-10 parts; Coupling agent 0.5-5 parts; Catalyst 0.05-1 part; The first crosslinking agent includes one or more of dicumyl peroxide, benzoyl peroxide, toluene diisocyanate, and hexamethylene diisocyanate; and the second crosslinking agent includes polymethylhydrogen siloxane.

2. The thermally-conductive, water-blocking sealant of claim 1, wherein, The methyl vinyl siloxane has a mole fraction of vinyl siloxane of 0.001%-0.004%.

3. The thermally conductive, water-blocking sealant of claim 1 or 2, wherein, The first crosslinking agent includes dicumyl peroxide and toluene diisocyanate, and the mass ratio of the dicumyl peroxide to the toluene diisocyanate is 1:1-3.

4. The thermally-conductive, water-blocking sealant of claim 1 or 2, wherein, The diamond alloy particles include one or more of copper diamond alloy particles and aluminum diamond alloy particles. The lignin includes one or more of alkali lignin, lignin sulfonate, organic solvent lignin, and ionic liquid lignin.

5. The thermally-conductive, water-blocking sealant of claim 1 or 2, wherein, The thermal-conducting water-resistant sealant further includes a diamond surface modifier in a mass fraction of 0.5-10 parts, and the diamond surface modifier includes one or more of 3-mercaptopropyltrimethoxysilane and γ-aminopropyltriethoxysilane.

6. The thermally-conductive, water-blocking sealant of claim 1 or 2, wherein, The coupling agent includes one or more of silane coupling agent, titanate coupling agent, phosphate coupling agent, and borate coupling agent.

7. The thermally-conductive, water-blocking sealant of claim 6, wherein, The coupling agent includes silane coupling agent KH550 and silane coupling agent KH560, and the mass ratio of the silane coupling agent KH550 to the silane coupling agent KH560 is 1-4:

1.

8. The thermally-conductive, water-blocking sealant of any one of claims 1-2, 7, wherein, The catalyst includes one or more of triethylamine, N,N-dimethylethanolamine, N,N-dimethylbenzylamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N',N''-pentamethyldiethylenetriamine, bis-(2-dimethylaminoethyl) ether, 1,4-diazabicyclo[2.2.2]octane, and tetramethylammonium hydroxide.

9. A method of preparing the heat-conducting water-blocking sealant according to any one of claims 1 to 8, characterized by, The method includes the following steps: The methyl vinyl siloxane, the lignin, the first crosslinking agent, and the catalyst are stirred and reacted at 120-140°C for 2.5-4 hours to obtain a base material by mass fraction; The diamond particles and / or the diamond alloy particles, the second crosslinking agent, the coupling agent, and the base material are mixed and reacted to obtain the thermal-conducting water-resistant sealant.

10. A photovoltaic module, characterized by, The thermal-conducting water-resistant sealant of any one of claims 1-8 is used as a sealant for a junction box in the photovoltaic module.

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