Butyl hot melt adhesive for heat-conducting and water-blocking photovoltaic module and preparation method of butyl hot melt adhesive

Abstract

The invention discloses a butyl hot melt adhesive for a heat-conducting waterproof photovoltaic module and a preparation method. The butyl hot melt adhesive is prepared from the following raw materials in parts by weight: 5-15 parts of EVA resin, 20-30 parts of butyl rubber, 40-60 parts of acrylic resin, 80-90 parts of heat-conducting filler, 0.3-0.5 part of a silane coupling agent, 3-6 parts of a semi-reinforcing agent, 4-8 parts of paraffin, 3-5 parts of white oil and 2-6 parts of coumarone resin. Under the influence of external factors such as outdoor long-time sunlight irradiation and acid rain corrosion, material aging and module failure caused by heat accumulation of the photovoltaic module can be effectively prevented, and meanwhile external water vapor is prevented from entering the battery piece and the junction box; and the problems of electric leakage damage and the like caused by erosion damage due to severe environment and long-time sunlight irradiation are effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of heat-conducting and waterproof materials, and in particular to a butyl hot-melt adhesive for a heat-conducting and water-blocking photovoltaic module and a preparation method thereof. Background Art

[0002] In recent years, with the growing demand for clean energy and renewable resources, my country's photovoltaic cell industry has developed rapidly and gradually moved towards industrialization. Technological progress has become an important factor in reducing the cost of solar photovoltaic power generation and promoting the development of the crystalline silicon solar cell industry and market.

[0003] Solar cell modules are the core part of solar power systems. They are mainly composed of solar cells, sealants, glass, back panels, junction boxes, etc., and have the function of converting solar energy into direct current. However, the use environment of solar cell modules is often outdoor, and is accompanied by relatively harsh application scenarios such as heat accumulation caused by high ambient temperature, water vapor convection, humidity, dust and sand, and light exposure time, which will soon cause the sealant to age and lose its function. With the increasing number of hot and humid weather, sufficient light and water erosion, the cost caused by environmental damage is increasing rapidly year by year. In order to effectively solve this problem, higher requirements need to be placed on the packaging technology of the battery pack in terms of heat dissipation, and the thermal conductivity and water vapor barrier properties of the solar cell module sealant must be strengthened.

[0004] The assembly line is also called the packaging line. Packaging is a key step in the production of solar cells. Without a good packaging process, no matter how good the battery is, it is impossible to produce a good assembly board. The subpackaging of the battery can not only ensure the life of the battery, but also increase the battery's impact strength. The high quality and long life of the product are the key to winning customer satisfaction, so the packaging quality of the assembly board is very important. At present, the assembly packaging technology on the market mainly adopts two packaging processes. The first internal structure uses EVA or PVB hot melt adhesive to ensure the vacuum and airtightness of the battery cell. The second is to use silicone sealant to bond the external aluminum frame to achieve a certain use strength to ensure the sealing of the component. However, in a high temperature environment, when the heat accumulates to a certain extent, it will cause the material to age and lose the sealing effect.

[0005] Currently, butyl rubber and silicone rubber are widely used due to their long-lasting sealing, good chemical stability, and good glass-metal bonding properties. However, this technical solution cannot solve the problem of heat accumulation caused by long-term exposure to sunlight, which is difficult to dissipate. It will cause thermal stress concentration in the junction box and the frame aluminum plate, accelerate material aging and cause bonding failure. At the same time, the water vapor transmission rate surges at high temperatures, corroding the internal structure of the battery pack and seriously affecting the working stability of the photovoltaic module.

[0006] In order to ensure that the adhesive material can be used in high temperature and high humidity water vapor environment, butyl polymers with low water vapor permeability are usually used. This technical solution usually only solves good water barrier properties in low temperature environments. In high temperature environments such as desert environments where direct sunlight can reach 70-80 degrees Celsius, the accumulation of heat will accelerate the aging of the material, making it difficult to take into account all application scenarios. In addition, when the high temperature and high humidity environment causes the unreactive small molecules in the adhesive material to hydrolyze with water in the air, it is difficult to ensure the excellent water barrier properties of the sealing material.

[0007] The thermally conductive butyl hot melt adhesive not only has a bonding effect, but also can prevent water vapor from invading the interior of the component in high and low temperature environments, allowing it to operate stably. Summary of the invention

[0008] The purpose of the present invention is to provide a butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules and a preparation method thereof in view of the problems existing in the prior art. The preparation raw materials include the following components, by weight: 5-15 parts of EVA resin, 20-30 parts of butyl rubber, 40-60 parts of acrylic resin, 80-90 parts of thermal conductive filler, 0.3-0.5 parts of silane coupling agent, 3-6 parts of semi-reinforcing agent, 4-8 parts of paraffin, 3-5 parts of white oil and 2-6 parts of coumarone resin.

[0009] Preferably, the EVA resin has a VA content of 18-33 and a melt index of 6-800.

[0010] Preferably, the butyl rubber is one or more combinations of common butyl rubber, chlorinated butyl rubber and brominated butyl rubber, and its viscosity average molecular weight is (35-45)*104.

[0011] Preferably, the acrylic resin is a thermoplastic acrylic resin having a number average molecular weight of 75,000 to 150,000.

[0012] Preferably, the thermally conductive filler is selected from one or more of spherical alumina, needle-shaped zinc oxide, flake boron nitride, light calcium carbonate, spherical silica, aluminum nitride, and talc.

[0013] Preferably, the silane coupling agent is one or more of trivinylsilane, vinyltri(dimethylsiloxy)silane, vinyltri(2-methoxyethoxy)silane, and vinylsilane.

[0014] Further preferably, the silane coupling agent is a product obtained by grafting trivinylsilane, vinyl tri(dimethylsiloxy)silane, vinyl tri(2-methoxyethoxy)silane or vinyl silane with one or more of isoprene, butadiene, styrene or maleic anhydride through free radical polymerization with one or more initiators being azobisisobutyronitrile, dibenzoyl peroxide, tert-butyl peroxypentylate or potassium persulfate; or one or more lipophilic modified products obtained by free radical polymerization with one or more initiators being azobisisobutyronitrile, dibenzoyl peroxide, tert-butyl peroxypentylate or potassium persulfate.

[0015] Preferably, the semi-reinforcing agent comprises carbon black and fumed silica.

[0016] Preferably, the paraffin wax is one or more of fully refined paraffin wax, semi-refined paraffin wax and crude paraffin wax.

[0017] Preferably, the relative density of the coumarone resin is 1.05 to 1.15 g / cm3.

[0018] According to another aspect of the present invention, a method for preparing a butyl hot melt adhesive for a thermally conductive and water-resistant photovoltaic module is provided, comprising the following steps: (1) Preheat the kneader to 70-90°C and use scissors to cut the butyl rubber into small pieces.

[0019] (2) Add EVA resin and thermoplastic acrylic resin into a kneader and plasticize for 20-45 minutes; (3) Raise the kneading machine temperature to 80-90°C, add thermal conductive filler, silane coupling agent, semi-reinforcing agent, paraffin, white oil, and coumarone resin, and continue kneading for 30-50 minutes; (4) The temperature of the kneading machine is raised to 130-150°C, and the internal pressure is evacuated to 0.08-0.1 MPa. The kneading is performed at a temperature of 140-180°C for 40-60 minutes to obtain a uniform adhesive material. The material is discharged to obtain a butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules. The beneficial effects of the present invention are as follows: The main principle of the present invention is that after the thermal conductive filler is modified by a silane coupling agent, a chemical bond can be formed between the filler and the matrix resin, thereby enhancing the interaction between the filler and the matrix resin, thereby reducing phonon scattering at the interface and improving the thermal conductivity of the hot melt adhesive. The surface energy of the modified thermal conductive filler is reduced and it is not easy to agglomerate. After the filler is compounded and used, more and more effective heat conduction paths can be formed in the hot melt adhesive system. At the same time, the molecular chain entanglement of butyl rubber can block the penetration of water vapor, so that the photovoltaic module hot melt adhesive has good thermal conductivity, low water vapor permeability, and heat and UV aging resistance during use, which increases the service life of the photovoltaic module. In addition, after compounding the thermal conductive filler, the problem of nanofiller agglomeration in the matrix can be greatly improved, more effective thermal conductive networks can be established, and the interface area can be improved, the phonon scattering at the interface can be reduced, and the thermal conductivity of the thermal conductive composite material can be improved. At the same time, the arrangement of the isoprene and isobutylene side methyl groups in butyl rubber can achieve the effect of blocking water vapor penetration, effectively preventing the active groups from being oxidized, thereby accelerating material aging. The thermal conductive network dissipates heat, thereby improving the lap strength, wet heat aging lap strength, barrier efficiency and insulation of butyl hot melt adhesive for solar photovoltaic modules. DETAILED DESCRIPTION

[0020] In order to make the objectives, technical solutions and advantages of the present invention more clear, the method of the present invention is described below through specific implementation examples. This description is only used to explain the present invention and is not intended to limit the present invention.

[0021] The term "preferred" in the present invention refers to embodiments of the present invention that can provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.

[0022] The present invention provides a butyl hot melt adhesive for a thermally conductive and water-resistant photovoltaic module. The raw materials for preparation include the following components, measured by weight: 5-15 parts of EVA resin, 20-30 parts of butyl rubber, 40-60 parts of acrylic resin, 80-90 parts of thermally conductive filler, 0.3-0.5 parts of silane coupling agent, 3-6 parts of semi-reinforcing agent, 4-8 parts of paraffin, 3-5 parts of white oil, and 2-6 parts of coumarone resin.

[0023] In one embodiment, the EVA resin has a VA content of 18-33 and a melt index of 6-800.

[0024] In one embodiment, the butyl rubber is one or more combinations of common butyl rubber, chlorinated butyl rubber and brominated butyl rubber, and the viscosity average molecular weight thereof is (35-45)*104.

[0025] In one embodiment, the acrylic resin is a thermoplastic acrylic resin having a number average molecular weight of 75,000 to 150,000.

[0026] In a preferred embodiment, the thermally conductive filler is selected from one or more of spherical aluminum oxide, needle-shaped zinc oxide, flake boron nitride, light calcium carbonate, spherical silicon dioxide, aluminum nitride, and talc.

[0027] In a preferred embodiment, the silane coupling agent is one or more of trivinylsilane, vinyltri(dimethylsiloxy)silane, vinyltri(2-methoxyethoxy)silane, and vinylsilane.

[0028] In one embodiment, the semi-reinforcing agent comprises carbon black and fumed silica.

[0029] In one embodiment, the paraffin wax is one or more of fully refined paraffin wax, semi-refined paraffin wax and crude paraffin wax.

[0030] In one embodiment, the relative density of the coumarone resin is 1.05 to 1.15 g / cm 3 .

[0031] In one embodiment, the weight ratio of the spherical aluminum oxide, aluminum nitride and needle-shaped zinc oxide is 0.6:1:2.

[0032] In one embodiment, the weight ratio of the flaky boron nitride to light calcium carbonate is 0.8:1.

[0033] In one embodiment, the weight ratio of the light calcium carbonate, talc and spherical silicon dioxide is 2:1:2.

[0034] In one embodiment, the semi-reinforcing agent comprises carbon black and fumed silica.

[0035] In one embodiment, the weight ratio of the carbon black to the fumed silica is 2:1.

[0036] In one embodiment, the weight ratio of the carbon black to the fumed silica is 6:0.6.

[0037] In one embodiment, the weight ratio of the carbon black to the fumed silica is 4:0.8. In one embodiment, the other additives include coumarone resin and white oil.

[0038] In one embodiment, the weight ratio of the coumarone resin to the white oil is 1.2:1.8.

[0039] In a preferred embodiment, the weight ratio of the coumarone resin to the white oil is 0.8:2.6.

[0040] In one embodiment, the weight ratio of the coumarone resin to the white oil is 1:2.8.

[0041] The butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules comprises the following components in parts by weight: 5-15 parts by weight of EVA resin, 25-29 parts by weight of butyl rubber, 40-50 parts by weight of acrylic resin, 0.3-0.5 parts by weight of silane coupling agent, 30-50 parts by weight of boron nitride, 10-20 parts by weight of light calcium carbonate, 0.2-1.0 parts by weight of white carbon black, 3-6 parts by weight of carbon black, 4-8 parts by weight of paraffin wax, 3-5 parts by weight of white oil and 2-6 parts of coumarone resin.

[0042] In one embodiment, a butyl hot melt adhesive for a thermally conductive and water-resistant photovoltaic module comprises the following components in parts: 10 parts of EVA resin, 25 parts of butyl rubber, 40 parts of acrylic resin, 0.4 parts of silane coupling agent, 30 parts of boron nitride, 10 parts of light calcium carbonate, 0.8 parts of white carbon black, 6.0 parts of carbon black, 4.6 parts of paraffin, 3.6 parts of white oil and 3.0 parts of coumarone resin.

[0043] The second aspect of the present invention provides a method for preparing a butyl hot melt adhesive for a thermally conductive and water-resistant photovoltaic module, comprising the following steps: (1) Preheat the kneader to 70-90°C and use scissors to cut the butyl rubber into small pieces.

[0044] (2) Add EVA resin and thermoplastic acrylic resin into a kneader and plasticize for 20-45 minutes; (3) Raise the kneading machine temperature to 80-90°C, add thermal conductive filler, silane coupling agent, semi-reinforcing agent, paraffin, white oil, and coumarone resin, and continue kneading for 30-50 minutes; (4) The temperature of the kneading machine is raised to 130-150°C, and the internal pressure is evacuated to 0.08-0.1 MPa. The kneading is performed at a temperature of 140-180°C for 40-60 minutes to obtain a uniform adhesive material. The material is discharged to obtain a butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules.

[0045] The silane coupling agent in Examples 1-3 and Comparative Example is trivinylsilane.

[0046] Example 1 A butyl hot melt adhesive for a thermally conductive and water-resistant photovoltaic module. The raw materials for preparation include the following components, measured in parts: 11 parts of EVA resin, 30 parts of butyl rubber, 50 parts of acrylic resin, 25 parts of light calcium carbonate, 40 parts of boron nitride, 15 parts of silicon dioxide, 0.5 parts of silane coupling agent, 1 part of white carbon black, 3 parts of carbon black, 4 parts of paraffin, 3 parts of white oil and 2 parts of coumarone resin.

[0047] The preparation method of butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules comprises the following steps: (1) Preheat the kneader to 80°C and use scissors to cut the butyl rubber into small pieces.

[0048] (2) Add EVA resin and thermoplastic acrylic resin into a kneader and plasticize for 35 minutes; (3) Raise the kneading machine temperature to 85°C, add thermal conductive filler, silane coupling agent, semi-reinforcing agent, paraffin, white oil, and coumarone resin, and continue kneading for 40 minutes; (4) The temperature of the kneading machine is raised to 140°C, and the internal pressure is evacuated to 0.09 MPa. The kneading is performed at 170°C for 55 minutes to obtain a uniform adhesive material. The material is discharged to obtain a butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules.

[0049] Example 2 A butyl hot melt adhesive for a thermally conductive and water-resistant photovoltaic module. The preparation raw materials comprise the following components, measured in parts: 15 parts of EVA resin, 29 parts of butyl rubber, 50 parts of acrylic resin, 35 parts of spherical alumina, 35 parts of silicon dioxide, 30 parts of needle-shaped zinc oxide, 0.4 parts of silane coupling agent, 2 parts of white carbon black, 0.5 parts of carbon black, 5 parts of paraffin, 4 parts of white oil and 5 parts of coumarone resin.

[0050] The preparation method is the same as Example 1.

[0051] Example 3 A butyl hot melt adhesive for a thermally conductive and water-resistant photovoltaic module. The raw materials for preparation include the following components, measured in parts: 15 parts of EVA resin, 25 parts of butyl rubber, 40 parts of acrylic resin, 30 parts of zinc oxide, 30 parts of spherical alumina, 25 parts of aluminum nitride, 0.3 parts of silane coupling agent, 2 parts of white carbon black, 2 parts of carbon black, 4 parts of paraffin, 5 parts of white oil and 6 parts of coumarone resin.

[0052] The preparation method is the same as Example 1.

[0053] Comparative Example 1 Based on Example 1, no silane coupling agent was included in the composition.

[0054] Comparative Example 2 Based on Example 1, no butyl rubber was included in the composition.

[0055] Comparative Example 3 Based on Example 1, no white oil was included in the composition.

[0056] Example 4 Based on Example 1, the silane coupling agent is isoprene grafted with trivinylsilane by free radical polymerization, the initiator is azobisisobutyronitrile, the feed mass ratio of isoprene to trivinylsilane is 1:1, azobisisobutyronitrile accounts for 0.7% of the total mass, and the reaction is carried out at 80° C. for 3 hours. Table 1 shows the performance test of the butyl hot melt adhesive used in the thermally conductive and water-resistant photovoltaic module of the present invention.

[0057] Table 1 Comparison of relevant properties of the material examples of the present invention

[0058] It can be seen from Example 1 and Comparative Examples 1-3 that in the absence of a silane coupling agent, the thermal conductivity of the material decreases. This may be because the nanoparticles aggregate due to their own high surface energy during the filling process, and the heat conduction paths formed inside the material are less, resulting in a decrease in heat conduction efficiency. Secondly, the phonon scattering at the interface between the filler and the matrix resin is more serious, which affects heat conduction. In the absence of butyl rubber, the barrier effect of water vapor molecules decreases due to the lack of a tightly arranged methyl structure like butyl rubber. White oil increases the compatibility of the filler and the matrix in the material, but the effect is not very obvious.

[0059] It can be seen from Examples 1 and 4 that after the silane coupling agent is modified, the thermal conductivity and shear strength of the material are improved to a certain extent. This may be because after the small molecules are grafted, the compatibility between the silicon series molecules and the carbon-based molecules becomes better, and secondly, a chemical connection is formed between the filler and the matrix, and there is a strong interaction. At the same time, due to the presence of the silane coupling agent, the interaction between the matrix and the filler is strengthened, which not only reduces the phonon scattering at the interface between the filler and the matrix, but also reduces the agglomeration of nanoparticles, increases more heat conduction paths, and increases the thermal conductivity while improving the strength of the material.

[0060] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules, characterized in that: The raw materials include the following components by weight: 5-15 parts of EVA resin, 20-30 parts of butyl rubber, 40-60 parts of acrylic resin, 80-90 parts of thermal conductive filler, 0.3-0.5 parts of silane coupling agent, 3-6 parts of semi-reinforcing agent, 4-8 parts of paraffin, 3-5 parts of white oil and 2-6 parts of coumarone resin.

2. The butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules according to claim 1, characterized in that: The EVA resin has a VA content of 18-33 and a melt index of 6-800; The butyl rubber is one or more combinations of common butyl rubber, chlorinated butyl rubber and brominated butyl rubber, and its viscosity average molecular weight is (35-45)*104.

3. The butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules according to claim 1, characterized in that: The acrylic resin is a thermoplastic acrylic resin, and its number average molecular weight is 75000-150000.

4. The butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules according to claim 1, characterized in that: The thermal conductive filler is selected from one or more of spherical aluminum oxide, needle-shaped zinc oxide, flake boron nitride, light calcium carbonate, spherical silicon dioxide, aluminum nitride, and talc.

5. The butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules according to claim 1, characterized in that: The silane coupling agent is one or more of trivinylsilane, vinyltri(dimethylsiloxy)silane, vinyltri(2-methoxyethoxy)silane, and vinylsilane.

6. The butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules according to claim 5, characterized in that: The silane coupling agent is a product obtained by grafting trivinylsilane, vinyl tri(dimethylsiloxy)silane, vinyl tri(2-methoxyethoxy)silane or vinyl silane with one or more of isoprene, butadiene, styrene or maleic anhydride through free radical polymerization with one or more initiators being azobisisobutyronitrile, dibenzoyl peroxide, tert-butyl peroxypentylate or potassium persulfate; or one or more lipophilic modified products obtained by free radical polymerization with one or more initiators being azobisisobutyronitrile, dibenzoyl peroxide, tert-butyl peroxypentylate or potassium persulfate.

7. The butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules according to claim 1, characterized in that: The semi-reinforcing agent comprises carbon black and fumed silica.

8. The butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules according to claim 1, characterized in that: The paraffin wax is one or more of fully refined paraffin wax, semi-refined paraffin wax and crude paraffin wax.

9. The butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules according to claim 1, characterized in that: The relative density of the coumarone resin is 1.05-1.15 g / cm 3 .

10. The method for preparing a butyl hot melt adhesive for a thermally conductive and water-resistant photovoltaic module according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Preheat the kneader to 70-90°C and use scissors to cut the butyl rubber into small pieces. (2) Add EVA resin and thermoplastic acrylic resin into a kneader and plasticize for 20-45 minutes; (3) Raise the kneading machine temperature to 80-90°C, add thermal conductive filler, silane coupling agent, semi-reinforcing agent, paraffin, white oil, and coumarone resin, and continue kneading for 30-50 minutes; (4) The temperature of the kneading machine is raised to 130-150°C, and the internal pressure is evacuated to 0.08-0.1 MPa. The kneading is performed at a temperature of 140-180°C for 40-60 minutes to obtain a uniform adhesive material. The material is discharged to obtain a butyl hot melt adhesive for thermally conductive and water-resistant photovoltaic modules.

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