Substrate and preparation method thereof, and BIPV photovoltaic module

Abstract

The application discloses a kind of substrate and preparation method thereof, and BIPV photovoltaic module, belong to BIPV field, a kind of substrate, including substrate layer, primer layer and heat-conducting coating, at least one side of substrate layer has primer layer, at least one primer layer has heat-conducting coating away from the side of substrate layer.The raw material of substrate layer includes the following components by mass fraction: cement 20-40 parts, siliceous material 35-60 parts, industrial calcium hydroxide 4-10 parts, reinforcing fiber 7-12 parts, multi-walled carbon nanotube dispersion 0.1-1 parts, silicon carbide powder 3-10 parts, alumina powder 3-8 parts, additives 0.4-2 parts.The substrate and preparation method thereof of the application, and BIPV photovoltaic module, by the component allocation ratio limitation of raw material of substrate layer, especially by adding multi-walled carbon nanotube dispersion, silicon carbide powder and alumina powder, so that substrate layer has the characteristics of high strength, low water absorption, high thermal conductivity, combined with the setting of primer layer and heat-conducting coating has higher high thermal conductivity and lower low water absorption.

Description

Technical Field

[0001] This invention belongs to the field of BIPV, and particularly relates to a substrate and its preparation method, as well as BIPV photovoltaic modules. Background Technology

[0002] BIPV is an abbreviation for "Building-Inverted Photovoltaics." It is a new type of building material and technology that integrates photovoltaic panels onto the exterior walls, roofs, and other surfaces of buildings, combining photovoltaic power generation with architectural decoration. BIPV originated in Europe and, with the continuous development and application of solar photovoltaic power generation technology, has now become an emerging field worldwide.

[0003] The existing BIPV photovoltaic module substrates do not have sufficient impact resistance and fire resistance (fire rating A), and cannot better adapt to the various installation environment requirements in buildings. In order to solve the problem of insufficient impact resistance and fire resistance (fire rating A) of the substrates, fiber cement boards, which are commonly used in building exterior wall decoration, can be used as substrates. However, conventional asbestos-free fiber cement flat panels or asbestos-free fiber reinforced calcium silicate boards used for exterior wall decoration, due to energy-saving requirements, aim to minimize thermal conductivity while ensuring physical properties. For example, JG / T 412.1-2018 "Fiber Cement Flat Panels Part 1: Asbestos-Free Fiber Cement Flat Panels" requires asbestos-free fiber cement boards to have a thermal conductivity ≤0.45; JG / T 564.1-2018 "Fiber Reinforced Calcium Silicate Boards Part 1: Asbestos-Free Fiber Reinforced Calcium Silicate Boards" requires asbestos-free fiber reinforced calcium silicate boards to have a thermal conductivity ≤0.35. However, inorganic boards used as photovoltaic module substrates need to have a high thermal conductivity. This serves two purposes: 1) During hot pressing of the modules, it allows for faster heat conduction, shortening the hot pressing time and improving module production efficiency; 2) During actual use, photovoltaic modules experience temperature increases due to sunlight and heat generation, which affects the module's power generation efficiency and lifespan. Therefore, increasing the thermal conductivity of the inorganic substrate is necessary to improve the overall heat dissipation performance of the module. When using inorganic substrates from exterior wall decorations as substrates for BIPV photovoltaic modules, a low water absorption rate is required to ensure the quality of the module's hot-pressing process and its durability. Therefore, there is an urgent need for a substrate with high thermal conductivity and low water absorption, its preparation method, and BIPV photovoltaic modules. Summary of the Invention

[0004] The purpose of this invention is to provide a substrate and its preparation method, as well as a BIPV photovoltaic module, to overcome at least one of the above-mentioned defects in the prior art.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] The present invention provides a substrate comprising a substrate layer. The raw materials of the substrate layer, by mass parts, include the following components: 20-40 parts of cement, preferably 25-30 parts; 35-60 parts of siliceous material, preferably 45-50 parts; 4-10 parts of industrial calcium hydroxide, preferably 5-7 parts; 7-12 parts of reinforcing fiber, preferably 8 parts; 0.1-1 part of multi-walled carbon nanotube dispersion, preferably 0.4-0.5 parts; 3-10 parts of silicon carbide powder, preferably 7 parts; 3-8 parts of alumina powder, preferably 5 parts; and 0.4-2 parts of additives, preferably 0.5 parts.

[0007] Preferably, it further includes a primer layer, and at least one side of the substrate layer has the primer layer.

[0008] Preferably, it further includes a thermally conductive coating, wherein at least one primer layer has a thermally conductive coating on one side away from the substrate layer.

[0009] Preferably, the multi-walled carbon nanotube dispersion is a dispersion of carboxylated modified multi-walled carbon nanotubes in water, with a concentration of 2-12 wt%, preferably 10 wt%. The carboxylated modified multi-walled carbon nanotubes have an outer diameter of 5-100 nm, preferably 30-80 nm, a length of 5-30 μm, preferably 10 μm, and a specific surface area of ​​60-500 m². 2 / g, preferably 60-100m 2 / g, with a carboxyl content of 0.2-4wt%, preferably 0.5-0.7wt%.

[0010] Preferably, the silicon carbide powder is α-crystalline silicon carbide powder with an average particle size of 5-50 μm, more preferably 5-10 μm, and a silicon carbide content of 75-99 wt%, more preferably >98%. The alumina powder is spherical alumina powder with an average particle size of 10-120 μm, more preferably 15-20 μm.

[0011] Preferably, the siliceous material is quartz sand with a silicon content of ≥90%, preferably ≥95%, and a particle size of 35-80μm, preferably 45-55μm. The industrial calcium hydroxide has an effective calcium content of ≥80%, preferably ≥95%, and a particle size of 20-45μm, preferably 40-45μm. The reinforcing fiber is plant fiber, which is one or more of softwood pulp, wood fiber extracted from waste paper, and cotton pulp, preferably bleached sulfate softwood pulp, with a length of 2-3mm. The additives include, by weight, 0.2-1 parts of polycarboxylate water-reducing agent, preferably 0.3-0.4 parts, and 0.2-1 parts of polyether-modified mineral oil defoamer, preferably 0.2-0.3 parts.

[0012] Preferably, the primer layer is a penetrating sealing primer layer, specifically one of water-based polyurethane penetrating primer, water-based epoxy penetrating primer, and UV penetrating primer, and the thermally conductive coating is one of water-based polyurethane thermally conductive paint, water-based epoxy thermally conductive paint, and silicone thermally conductive paint.

[0013] The present invention also provides a substrate preparation method for preparing the above-mentioned substrate, comprising the following steps: S1: preparing a substrate layer; S2: selecting a primer, and then applying the primer to at least one side of the substrate layer, and drying the primer after application to form a primer layer; S3: selecting a thermally conductive paint, and then applying the thermally conductive paint to at least one side of the primer layer away from the substrate layer, and drying the thermally conductive paint after application to form a thermally conductive coating, thereby completing the preparation of the substrate.

[0014] Preferably, in step S1, the substrate layer is sanded to 200-280 grit, and in step S2, the amount of primer applied is 45-55 g / m². 2 The coating method is roller coating or spray coating. Drying conditions: drying at 23-27℃ for more than 24 hours, or drying at 70-80℃ for more than 6 hours. In step S3, the coating amount of thermally conductive paint is 75-85 g / m². 2 The coating method is roller coating or spray coating. Drying conditions: dry at 23-27℃ for more than 12 hours, or dry at 70-80℃ for more than 4 hours.

[0015] Preferably, in step S1, the method for preparing the substrate layer includes the following steps: S11: Slurry preparation: S111: Pre-treat the reinforcing fibers to obtain wood pulp (200 kg), with the wood pulp mass concentration controlled at 4%; S112: Add 0.4-2 parts of additives to water, disperse evenly at high speed, then add 0.1-1 parts of multi-walled carbon nanotube dispersion, disperse evenly, to obtain a liquid mixture (200-325 kg); S113: Mix 20-40 parts of cement, 35-60 parts of siliceous material, 4-10 parts of industrial calcium hydroxide, 3-10 parts of silicon carbide powder, and 3-8 parts of alumina powder evenly to obtain a solid mixture (92 kg); S114: First, mix the wood pulp obtained in step S111 with the... After the liquid mixture obtained in step S112 is mixed evenly, the solid mixture obtained in step S113 is slowly added and pulped. The pulp concentration is controlled at 16%-20% to obtain slurry. S12: Wet blank forming. The slurry prepared in step S114 is directly flowed onto the running felt to form a thin layer. After vacuum dehydration, it is dehydrated under pressure and wound into a blank. When the blank reaches the specified thickness, it is cut to obtain a wet blank. S13: Wet blank pressurization. The wet blanks formed in step S12 are stacked and pressurized. They need to be pressurized for 30 minutes by a hydraulic press of more than 8,000 tons to pressurize the wet blanks under a high pressure of more than 25 MPa to improve the strength and density of the board. S14: Pre-curing of wet blanks: The wet blanks after the pressure treatment in step S13 are pre-cured to obtain a blank body. S15: Steam curing: The blank body obtained by pre-curing in step S14 is steam-cured to obtain a slab. S16: Drying and sanding: The slab cured in step S15 is dried to reduce its moisture content to less than 10 wt%, preferably 5-8 wt%, and then sanded to obtain a substrate layer.

[0016] Preferably, in step S14, the wet billet is pre-cured in a pre-curing kiln at a temperature of 30-50°C for 4-6 hours. In step S15, the billet is steam-cured in an autoclave for 16-24 hours at a temperature of 185-195°C and a steam pressure of 1.1-1.3 MPa.

[0017] Preferably, in step S2, the selected primers are components A and B, with a mass ratio of component A to component B of 1:(1-2), and a molar ratio of active hydrogen to epoxy groups of 1.05-1.1. Component A comprises the following raw materials by mass: 60-90 parts of epoxy resin, preferably 80-90 parts, and 10-40 parts of epoxy reactive diluent, preferably 10-20 parts. Component B comprises the following raw materials by mass: 65-95 parts of waterborne epoxy curing agent, preferably 85-90 parts, 5-35 parts of water, preferably 10-15 parts, 0.1-0.5 parts of wetting agent, preferably 0.2-0.3 parts, and 0.1-0.5 parts of defoamer, preferably 0.1-0.2 parts.

[0018] Preferably, the epoxy resin is E-44 epoxy resin, E-51 epoxy resin, or E-55 epoxy resin. The epoxy value of E-44 epoxy resin is 0.41-0.47 mol / 100g, the epoxy value of E-51 epoxy resin is 0.48-0.54 mol / 100g, and the epoxy value of E-55 epoxy resin is 0.55-0.56 mol / 100g. The epoxy reactive diluent is phenyl glycidyl ether (PGE) or dodecyl to tetradecyl glycidyl ether. The epoxy curing agent is a self-emulsifying nonionic waterborne epoxy curing agent with a solid content of 48-52 wt%, a viscosity of 300-1300 cps at a temperature of 23-27℃, an active hydrogen equivalent of 200-300 g / mol, a wetting agent of nonionic acetylenol modified surfactant, and a star-shaped polymer composite mineral oil defoamer.

[0019] Preferably, in step S3, the selected thermally conductive paint consists of components A and B, with a mass ratio of component A to component B of 10:(0.8-1.2), and a molar ratio of active hydrogen to epoxy groups of 0.8-0.9. Component A comprises the following raw materials by mass: 2.3-6.7 parts of additives, 15-25 parts of water, preferably 19-20 parts, 35-55 parts of aqueous epoxy emulsion, preferably 45 parts, 0.5-2.5 parts of dispersion of multi-walled carbon nanotubes, preferably 1.2-1.5 parts, 2-6 parts of flake graphite powder, preferably 2.5 parts, and 25-35 parts of alumina powder, preferably 28 parts. Component B comprises the following raw materials by mass: 65-95 parts of aqueous epoxy curing agent, preferably 85 parts, 1-5 parts of water, preferably 5 parts, and 6-12 parts of co-solvent, preferably 10 parts.

[0020] Preferably, the additives include the following raw materials in parts by weight: 0.1-0.5 parts of wetting agent, preferably 0.2 parts; 0.5-1.2 parts of polymeric dispersant, preferably 1 part; 0.3-1 part of ammonium salt dispersant, preferably 0.6 parts; 0.1-0.6 parts of defoamer, preferably 0.5 parts; 0.8-2 parts of film-forming aid, preferably 1.5 parts; and 0.6-2 parts of thickener, preferably 1.5 parts.

[0021] Preferably, the wetting agent is a high HLB value nonionic isomeric alcohol polyoxyethylene ether wetting agent with an HLB value of 17-18; the polymeric dispersant is a high molecular weight block copolymer solution containing pigment affinity groups; the ammonium salt dispersant is a hydrophobically modified ammonium acrylate copolymer dispersant; the defoamer is an organosilicon defoamer; the film-forming aid is dipropylene glycol butyl ether; the thickener is a medium-high shear polyurethane thickener; and the aqueous epoxy emulsion is an aqueous dispersion modified with nonionic bisphenol A solid epoxy resin, with a solid content of 48-52 wt%, an epoxy equivalent of 1000-1100 g / eq, a viscosity of 50-1000 cps, and a density of 1.05-1.12 g / cm³ at a temperature of 23-27°C. 3 The waterborne epoxy curing agent is a self-emulsifying nonionic waterborne epoxy curing agent with a solid content of 51-53 wt%. Under the condition of 23-27℃, the viscosity is 2000-5000 cps, the active hydrogen equivalent is 210-250 g / mol, and the co-solvent is one or more of propylene glycol methyl ether, dipropylene glycol methyl ether, and ethylene glycol monobutyl ether.

[0022] Preferably, the multi-walled carbon nanotube dispersion is a dispersion of carboxylated modified multi-walled carbon nanotubes in water, with a concentration of 2-12 wt%. The carboxylated modified multi-walled carbon nanotubes have an outer diameter of 30-80 nm, a length of 15-30 μm, and a specific surface area of ​​60-100 m². 2 / g, with a carboxyl content of 0.5-0.7wt%, the alumina powder is spherical alumina powder with an average particle size ≤20μm, and the flake graphite powder has an average particle size of 5-5.5μm.

[0023] Preferably, the room temperature thermal conductivity of the carboxylated modified multi-walled carbon nanotubes is 2800-3200 W / (M·K), the room temperature thermal conductivity of the flake graphite powder is 150-300 W / (M·K), and the room temperature thermal conductivity of the spherical alumina powder is 20-40 W / (M·K). The mass ratio of the carboxylated modified multi-walled carbon nanotubes to the flake graphite powder is 1:(15-20).

[0024] The present invention also provides a BIPV photovoltaic module, including the above-mentioned substrate, wherein a second encapsulating film layer, a photovoltaic cell module, a first encapsulating film layer, and a light-transmitting layer are sequentially disposed on the substrate.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. By limiting the proportion of raw materials in the substrate layer, especially by adding multi-walled carbon nanotube dispersion, silicon carbide powder, and alumina powder, the substrate layer has the characteristics of high strength, low water absorption, and high thermal conductivity, making it suitable for use in BIPV photovoltaic modules.

[0027] 2. By applying a primer layer, not only is adhesion enhanced and the bonding strength between the substrate layer and the thermally conductive coating improved, but it also seals the pores, preventing the substrate layer from absorbing moisture, generating air bubbles during the pressing process, and causing the substrate layer to deform. This reduces the overall water absorption rate of the substrate, ensuring that the entire system has better resistance to damp heat, weathering, and freezing, and a longer service life.

[0028] 3. The thermally conductive coating is used to improve the overall thermal conductivity of the system. On the one hand, it improves the thermal conductivity of the substrate during the hot pressing of the BIPV photovoltaic module, thereby increasing production efficiency; on the other hand, it improves the heat dissipation performance of the overall BIPV photovoltaic module during power generation, thereby increasing power generation efficiency and extending the life of the BIPV photovoltaic module.

[0029] 4. By controlling the mass ratio of carboxyl-modified multi-walled carbon nanotubes to flake graphite powder to be 1:(15-20), the multi-walled carbon nanotubes act as separators and bridges for the flake graphite powder, improving its dispersibility. Simultaneously, they form a better three-dimensional network of thermally conductive pathways, thereby enhancing the thermal conductivity of the thermally conductive paint. However, due to the poor dispersibility and large specific surface area of ​​both multi-walled carbon nanotubes and flake graphite, the amount added cannot be too large, otherwise it will affect the physical properties of the entire coating. Therefore, spherical alumina powder is added to further improve the thermal conductivity of the entire thermally conductive paint without affecting its physical properties. At the same time, the filler gradation structure of the entire thermally conductive paint is optimized. The spherical alumina powder can further fill the gaps between the flake graphite, forming a bridging network. There are also point-to-point contact connections between the alumina powder particles. Through this synergistic effect, more heat flow paths are formed, further improving the thermal conductivity of the thermally conductive paint.

[0030] 5. The physical properties of the prepared substrate fully meet the requirements for exterior wall panels. Furthermore, as a substrate for BIPV photovoltaic modules, to ensure the quality of the hot-pressing process and the durability of the modules, the substrate is coated with a waterproof sealant, reducing the water absorption rate to approximately 5%. To improve thermal conductivity during hot pressing and heat dissipation during module power generation, the thermal conductivity of the entire substrate is increased to over 1, better meeting the requirements for module production and use. Attached Figure Description

[0031] Figure 1 This is a three-dimensional structural schematic diagram of Embodiment 1 of the present invention.

[0032] Figure 2 This is a cross-sectional structural diagram of Embodiment 2 of the present invention.

[0033] Figure 3 yes Figure 2 A magnified structural diagram of A in the diagram.

[0034] The labels in the attached diagram are: 1-substrate layer, 2-primer layer, 3-thermal conductive coating, 4-second encapsulating film layer, 5-photovoltaic cell module, 6-first encapsulating film layer, 7-light-transmitting layer. Detailed Implementation

[0035] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0036] Contents not described in detail in this specification are prior art known to those skilled in the art. In the description of this invention, it should be understood that terms such as "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, terms such as "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] Example 1:

[0038] like Figure 1 As shown, the substrate provided in this embodiment includes a substrate layer 1, a primer layer 2, and a thermally conductive coating layer 3.

[0039] In this embodiment, the substrate layer 1 has a primer layer 2 on both the front and back sides, as well as on all four sides (top, bottom, left, and right). Of course, in other embodiments, the primer layer 2 may only be applied to the front and back sides of the substrate layer 1, or only to the front side (front face) of the substrate layer 1. The primer layer 2 is a water-based epoxy penetrating primer. The primer layer 2 not only enhances adhesion and improves the bonding strength between the substrate layer 1 and the thermally conductive coating 3, but also seals the pores, preventing the substrate layer 1 from absorbing moisture, generating air bubbles during the pressing process, and deforming. It also reduces the overall water absorption rate of the substrate, ensuring better resistance to damp heat, weathering, and freezing, and a longer service life for the entire system.

[0040] The primer layer 2 on both the front and rear sides has a thermally conductive coating 3 on the side furthest from the substrate layer 1. Of course, in other embodiments, only the primer layer on the front or rear side may have a thermally conductive coating. In this embodiment, the thermally conductive coating 3 is a water-based epoxy thermally conductive paint. The thermally conductive coating 3 is used to improve the overall thermal conductivity of the system. On the one hand, it improves the thermal conductivity efficiency of the substrate during the hot pressing of the BIPV photovoltaic module, thereby increasing production efficiency; on the other hand, it improves the heat dissipation performance of the overall BIPV photovoltaic module during power generation, thereby increasing power generation efficiency and extending the lifespan of the BIPV photovoltaic module.

[0041] The raw materials of substrate layer 1 in this embodiment include the following components by mass parts:

[0042] 26 parts of cement, which is 42.5R silicate cement.

[0043] 47 parts of siliceous material were collected. The siliceous material was quartz sand with a silicon content of 96% and a particle size of 50 μm.

[0044] Six parts of industrial calcium hydroxide (hydrated lime or quicklime) with an effective calcium content of 97% and a particle size of 42 μm.

[0045] Eight parts of reinforcing fiber were added. The reinforcing fiber was bleached sulfate softwood pulp with a length controlled at 2.5 mm.

[0046] 0.45 parts of a multi-walled carbon nanotube dispersion, which is a dispersion of carboxylated modified multi-walled carbon nanotubes in water, with a concentration of 10 wt%. The carboxylated modified multi-walled carbon nanotubes have an outer diameter of 50 nm, a length of 10 μm, and a specific surface area of ​​80 m². 2 / g, with a carboxyl content of 0.6wt%.

[0047] Carbon nanotubes are broadly classified into two categories: single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). Despite sharing some commonalities, their physical properties differ significantly due to structural differences. The most important distinguishing feature of SWCNTs is that they consist of only one layer of wall. In other words, SWCNTs can be described as seamless hollow cylinders formed by rolling up a single layer of graphene sheets. This is why they are often referred to as single-layer graphene nanotubes. Unlike SWCNTs, MWCNTs can be viewed as concentric arrangements of SWCNTs, i.e., formed by seamlessly rolling up multiple layers of graphene sheets into a tubular shape. These differences between SWCNTs and MWCNTs result in significantly different material properties when added to materials, thus having a corresponding impact on the overall material composition.

[0048] Carbon nanotubes (CNTs) are the ideal functional fillers for thermally conductive materials. Compared with other particulate heat-dissipating fillers, nanofiber-like CNTs are more likely to form thermally conductive networks, significantly enhancing the thermal conductivity of the system.

[0049] Theoretical calculations show that the room temperature thermal conductivity of single-walled carbon nanotubes is as high as 6600 W / M·K, while that of multi-walled carbon nanotubes reaches 3000 W / M·K. The thermal conductivity of commonly used fillers is shown in Table 1.

[0050] Packing name Thermal conductivity K (W / M·K) Beryllium oxide (toxic) 270 Aluminum nitride 80-320 Boron nitride 125 silicon carbide 83.6 magnesium oxide 36 Alumina 30 Zinc oxide 26 Silica (crystalline type) 10

[0051] Table 1

[0052] Seven parts of silicon carbide powder, which is α-silicon carbide (α-SiC) with an average particle size of 5 μm and a silicon carbide content of 99 wt%.

[0053] Five parts of alumina powder, which is spherical alumina powder with an average particle size of 18 μm.

[0054] Alumina powder can improve the thermal conductivity of substrate layer 1, reduce the coefficient of expansion, and appropriately increase the strength of substrate layer 1.

[0055] 1. Due to its high thermal conductivity, low price, and excellent flame retardant properties, alumina is the most widely used thermally conductive filler, and spherical alumina helps to give full play to the thermal conduction function of thermally conductive fillers.

[0056] 2. The calcium crystals (calcium hydroxide) generated during the hydration process of substrate layer 1 can form calcium aluminate hydrate with the surface of alumina, which increases the density of the hardened paste, thereby improving the strength and toughness of substrate layer 1.

[0057] By adding multi-walled carbon nanotube dispersion, silicon carbide powder, and alumina powder, substrate layer 1 has the characteristics of high strength, low water absorption, and high thermal conductivity, making it suitable for BIPV photovoltaic modules.

[0058] The additive is 0.5 parts, which includes 0.3 parts of polycarboxylate superplasticizer and 0.2 parts of polyether modified mineral oil defoamer by weight.

[0059] Example 2:

[0060] like Figures 2 to 3 As shown, this embodiment also provides a BIPV photovoltaic module, including the substrate of Embodiment 1. The substrate is provided with a second encapsulating film layer 4, a photovoltaic cell module 5, a first encapsulating film layer 6, and a light-transmitting layer 7 from bottom to top.

[0061] Example 3:

[0062] This embodiment also provides a substrate preparation method for preparing the substrate of Embodiment 1, including the following steps:

[0063] S1: Fabrication of substrate layer 1 includes the following steps:

[0064] S11: Slurry preparation:

[0065] S111: Pretreatment of reinforcing fibers:

[0066] Eight portions of bleached sulfate softwood pulp, each 2.5 mm in length, were passed through a pulper and a refiner for pulping and refining pretreatment to obtain 200 kg of wood pulp. The wood pulp concentration was controlled at 4%.

[0067] S112: Add 0.3 parts of polycarboxylate superplasticizer and 0.2 parts of polyether modified mineral oil defoamer to water in sequence, disperse evenly at high speed, and then add 0.45 parts of multi-walled carbon nanotube dispersion, disperse evenly to obtain a liquid mixture (200 kg).

[0068] S113: Mix 26 parts of 42.5R silicate cement, 47 parts of quartz sand, 6 parts of industrial calcium hydroxide, 7 parts of silicon carbide powder, and 5 parts of alumina powder in a mixer until homogeneous to obtain a solid mixture (92 kg). Before use, bake the silicon carbide powder in an oven at approximately 60°C for at least 8 hours to optimize its various properties.

[0069] S114: First, mix the wood pulp obtained in step S111 and the liquid mixture obtained in step S112 evenly, then slowly put the solid mixture obtained in step S113 into the mixture and perform pulping treatment. The pulping mass concentration is controlled at 20% to obtain pulp.

[0070] S12: Wet blank forming. The slurry prepared in step S114 is directly flowed into the running felt through the headbox to form a thin material layer. After vacuum dewatering, it is further dewatered under pressure in the forming cylinder and wound into a blank. When the blank reaches the specified thickness, the blank is cut to obtain a wet blank.

[0071] S13: Pressurize the wet blanks. Stack the wet blanks formed in step S12 and pressurize them.

[0072] S14: Pre-curing of wet billets. The wet billets after the pressure treatment in step S13 are pre-cured in a pre-curing kiln at a temperature of 40℃ for 5 hours to obtain the billet body. This allows the slab to acquire a certain early strength.

[0073] S15: Autoclaving. The billet obtained from the pre-curing in step S14 is placed in an autoclave for autoclaving for 20 hours at a curing temperature of 190℃ and a steam pressure of 1.2MPa to obtain a slab.

[0074] S16: Drying and sanding. The slab cured in step S15 is dried to a moisture content of 5 wt%. Then, the substrate layer 1 is sanded to 200-280 mesh to obtain substrate layer 1.

[0075] S2: Select a primer, then apply the primer to the front and back sides, and the top, bottom, left, and right sides of substrate layer 1. After applying the primer, allow it to dry to form primer layer 2. The primer application amount is 50g / m². 2 The coating method is roller coating or spray coating. Drying conditions: dry at 25℃ for more than 24 hours, or dry at 75℃ for more than 6 hours.

[0076] Specifically, the selected primers are components A and B, with a mass ratio of 1:1.5 between components A and B, and a molar ratio of 1.05 between active hydrogen and epoxy groups.

[0077] Component A comprises the following raw materials by mass parts:

[0078] 85 parts of epoxy resin, the epoxy resin is E-51 epoxy resin, and the epoxy value is 0.50 mol / 100g.

[0079] 15 parts of epoxy reactive diluent, the epoxy reactive diluent being butyl glycidyl ether.

[0080] Component B comprises the following raw materials by mass parts:

[0081] 86 parts of waterborne epoxy curing agent. The waterborne epoxy curing agent is a self-emulsifying nonionic waterborne epoxy curing agent with a solid content of 50wt%. At a temperature of 25℃, the viscosity is 1000cps and the active hydrogen equivalent is 250g / mol.

[0082] 13 parts water.

[0083] 0.25 parts of wetting agent, which is a nonionic acetylenic diol modified surfactant.

[0084] 0.15 parts of defoamer, which is a star-shaped polymer composite mineral oil defoamer.

[0085] S3: Select a thermally conductive paint, and then apply the thermally conductive paint to the side of both primer layers 2 away from the substrate layer 1. After applying the thermally conductive paint, dry it to form a thermally conductive coating layer 3, thus completing the substrate preparation. The coating amount of the thermally conductive paint is 80 g / m². 2 The coating method is roller coating or spray coating. Drying conditions: dry at 25℃ for more than 12 hours, or dry at 70-80℃ for more than 4 hours.

[0086] In step S3 of this embodiment, the thermally conductive paint selected consists of components A and B, with a mass ratio of component A to component B of 10:1 and a molar ratio of active hydrogen to epoxy groups of 0.85.

[0087] Component A comprises the following raw materials by mass parts:

[0088] 5.3 parts of additives. Specifically, the additives include the following raw materials by mass parts:

[0089] 0.2 parts of wetting agent, which is a high HLB value nonionic isomeric alcohol polyoxyethylene ether wetting agent with an HLB value of 17.

[0090] One part of a polymeric dispersant, which is a high molecular weight block copolymer solution containing pigment affinity groups.

[0091] 0.6 parts of ammonium salt dispersant, which is a hydrophobically modified ammonium acrylate copolymer dispersant.

[0092] 0.5 parts of defoamer, which is an organosilicon defoamer.

[0093] 1.5 parts of film-forming aid, which is dipropylene glycol butyl ether.

[0094] Thickener 1.5 parts, the thickener is a medium-high shear polyurethane thickener.

[0095] 19 portions of water.

[0096] 45 parts of an aqueous epoxy emulsion, which is an aqueous dispersion modified with nonionic bisphenol A solid epoxy resin, has a solid content of 50 wt%, an epoxy equivalent of 1000 g / eq, a viscosity of 800 cps and a density of 1.10 g / cm³ at 25°C. 3 ,

[0097] 1.3 parts of a dispersion of multi-walled carbon nanotubes (MWCNTs) were used. The MCCNT dispersion was a carboxylated MWCNT dispersion in water with a concentration of 10 wt%. The carboxylated MWCNTs had an outer diameter of 50 nm, a length of 20 μm, and a specific surface area of ​​80 m². 2 / g, with a carboxyl content of 0.7wt%.

[0098] 2.5 parts of flake graphite powder, which is high-purity thermally conductive graphite powder, specifically selected from natural flake graphite powder, with a carbon content greater than 95% and an average particle size of 5μm.

[0099] 28 parts of alumina powder, which is spherical alumina powder with an average particle size of 20μm.

[0100] Component B comprises the following raw materials by mass parts:

[0101] 85 parts of waterborne epoxy curing agent. The waterborne epoxy curing agent is a self-emulsifying nonionic waterborne epoxy curing agent with a solid content of 52wt%. At a temperature of 25℃, the viscosity is 3000cps and the active hydrogen equivalent is 230g / mol.

[0102] 5 parts water.

[0103] 10 parts of cosolvent, the cosolvent being propylene glycol methyl ether.

[0104] The method utilizes carboxylated modified multi-walled carbon nanotubes with a room temperature thermal conductivity of 3000 W / (M·K), flake graphite powder with a room temperature thermal conductivity of 200 W / (M·K), and spherical alumina powder with a room temperature thermal conductivity of 30 W / (M·K).

[0105] When the mass ratio of carboxylated modified multi-walled carbon nanotubes to flake graphite powder is 1:(15-20), on the one hand, the multi-walled carbon nanotubes play a role in separating and bridging the flake graphite powder, improving the dispersibility of the graphite powder, and on the other hand, they can form a better three-dimensional network thermal conductive pathway, thereby improving the thermal conductivity of the thermally conductive paint.

[0106] However, due to the poor dispersibility and large specific surface area of ​​multi-walled carbon nanotubes and flake graphite, the amount added cannot be too large, otherwise it will affect the physical properties of the entire coating. Therefore, spherical alumina powder is added to further improve the thermal conductivity of the entire thermally conductive paint without affecting its physical properties. At the same time, the filler gradation structure of the entire thermally conductive paint is optimized. Spherical alumina powder can further fill the gaps between flake graphite to form a bridging network. There are also point-to-point contact connections between the alumina powder particles. Through this synergistic effect, more heat flow paths are formed, further improving the thermal conductivity of the thermally conductive paint.

[0107] Table 2 shows a comparison between the performance indicators of substrate layer 1 obtained by the above method and the R3 grade of Class A exterior wall panels in the industry standard technical requirements:

[0108]

[0109] Table 2

[0110] The substrate prepared by the above method was tested according to the relevant items in JG / T 396-2012 "Non-load-bearing fiber-reinforced cement board for exterior walls"; the test results are shown in Table 3.

[0111]

[0112]

[0113] Table 3

[0114] The measured data show that the physical properties of the substrate prepared in this embodiment fully meet the requirements for exterior wall panels. Furthermore, as a substrate for BIPV photovoltaic modules, to ensure the quality of the hot-pressing process and the durability of the modules, the substrate is coated with a waterproof sealant, reducing the water absorption rate to approximately 5%. To improve thermal conductivity during hot pressing and heat dissipation during module power generation, the thermal conductivity of the entire substrate is increased to over 1, better meeting the requirements for module production and use.

[0115] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A substrate, characterized in that: comprising a substrate layer, a primer layer and a thermal conductive coating layer; the raw materials of the substrate layer comprise the following components in mass fraction: cement 20-40 parts; siliceous material 35-60 parts; industrial calcium hydroxide 4-10 parts; reinforcing fiber 7-12 parts; multi-walled carbon nanotube dispersion liquid 0.1-1 parts, the multi-walled carbon nanotube dispersion liquid in the substrate layer is a dispersion liquid of carboxylated modified multi-walled carbon nanotube dispersed in water; silicon carbide powder 3-10 parts; alumina powder 3-8 parts, the alumina powder is spherical alumina powder; additive 0.4-2 parts; at least one side of the substrate layer has the primer layer; at least one primer layer has a thermal conductive coating layer away from the side of the substrate layer; the thermal conductive coating layer comprises the following raw materials in mass fraction: multi-walled carbon nanotube dispersion liquid 0.5-2.5 parts; flake graphite powder 2-6 parts; alumina powder 25-35 parts; the multi-walled carbon nanotube dispersion liquid in the thermal conductive coating layer is a dispersion liquid of carboxylated modified multi-walled carbon nanotube dispersed in water, and the concentration is 2-12 wt%; the alumina powder in the thermal conductive coating layer is spherical alumina powder, and the average particle size is ≤20 μm; the average particle size of the flake graphite powder is 5-5.5 μm; the mass ratio of the carboxylated modified multi-walled carbon nanotube to the flake graphite powder in the thermal conductive coating layer is 1: (15-20). 2.The substrate according to claim 1, characterized in that: the concentration of the multi-walled carbon nanotube dispersion liquid in the substrate layer is 2-12 wt%; the silicon carbide powder is α crystal type silicon carbide powder, the average particle size is 5-50 μm, and the silicon carbide content is 75-99 wt%; the average particle size of the alumina powder in the substrate layer is 10-120 μm; the siliceous material is quartz sand, the silicon content is ≥90%, and the particle size is 35-80 μm; the effective calcium content of the industrial calcium hydroxide is ≥80%, and the particle size is 20-45 μm; the reinforcing fiber is plant fiber, which is one or more of conifer pulp, wood fiber extracted from waste paper, and cotton pulp; the additive comprises 0.2-1 parts of polycarboxylate superplasticizer and 0.2-1 parts of polyether modified mineral oil defoaming agent in mass fraction; the primer layer is one of water-based polyurethane penetrating primer, water-based epoxy penetrating primer and UV penetrating primer; and the thermal conductive coating layer is one of water-based polyurethane thermal conductive paint, water-based epoxy thermal conductive paint and silicone thermal conductive paint. A method for preparing the substrate according to any one of claims 1-2, comprising the following steps: S1: preparing a substrate layer; S2: selecting a primer, then coating the primer on at least one side of the substrate layer, and drying the primer after coating to form a primer layer; S3: selecting a thermal conductive paint, then coating the thermal conductive paint on at least one side of the primer layer away from the substrate layer, and drying the thermal conductive paint after coating to form a thermal conductive coating layer, thereby completing the preparation of the substrate. 4.The method according to claim 3, characterized in that: in step S1, the substrate layer is polished to 200-280 mesh. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The carboxyl-modified multi-walled carbon nanotubes in the heat-conducting coating have an outer diameter of 30-80 nm, a length of 15-30 μm, a specific surface area of 60-100 m 2 / g, and a carboxyl content of 0.5-0.7 wt%. ​ ​ ​ ​ ​ The carboxylated modified multi-walled carbon nanotubes in the substrate layer have an outer diameter of 5-100 nm, a length of 5-30 μm, a specific surface area of 60-500 m 2 / g, and a carboxyl content of 0.2-4 wt%. ​ ​ ​ ​ ​ ​ ​ ​ 3. A method of preparing a substrate, characterized by, ​ ​ ​ ​ ​ ​ The coating amount of the primer in step S2 is 45-55 g / m 2 The coating method is roller coating or spraying, and the drying conditions are 23-27 °C for 24 h or more, or 70-80 °C for 6 h or more. In step S3, the heat-conducting paint is applied in an amount of 75-85 g / m 2 by roller coating or spraying, and dried at 23-27°C for 12 hours or more, or at 70-80°C for 4 hours or more.

5. The substrate preparation method of claim 3, wherein In step S1, the preparation method of the substrate layer comprises the following steps: S11: slurry preparation: S111: pretreating the reinforcing fibers to obtain wood pulp; S112: adding 0.4-2 parts of an additive to water, uniformly dispersing at high speed, then adding 0.1-1 parts of a multi-walled carbon nanotube dispersion liquid, uniformly dispersing to obtain a liquid mixture; S113: uniformly mixing 20-40 parts of cement, 35-60 parts of siliceous material, 4-10 parts of industrial calcium hydroxide, 3-10 parts of silicon carbide powder, and 3-8 parts of aluminum oxide powder to obtain a solid mixture; S114: uniformly mixing the wood pulp obtained in step S111 and the liquid mixture obtained in step S112, then slowly putting the solid mixture obtained in step S113 into the mixture and performing a beating treatment to obtain a slurry; S12: wet blank forming, directly flowing the slurry prepared in step S114 to a running wool cloth to form a thin material layer, after vacuum dewatering, pressure dewatering and winding into a blank, when the blank reaches a specified thickness, cutting the blank to obtain a wet blank; S13: wet blank pressing, stacking the wet blank formed in step S12 and performing a pressing treatment; S14: wet blank pre-curing, pre-curing the wet blank after the pressing treatment in step S13, the pre-curing temperature is 30-50℃, the pre-curing time is 4-6h, and a blank body is obtained; S15: autoclave curing, autoclave curing the blank body obtained in step S14, the curing time is 16-24h, the curing temperature is 185-195℃, the steam pressure is 1.1-1.3MPa, and a plate blank is obtained; S16: drying and sanding, drying the plate blank obtained in step S15 to make the water content less than 10wt%, then performing a polishing treatment to obtain a substrate layer.

6. The substrate preparation method according to claim 3, wherein: In step S2, the selected primer is A and B components, the mass ratio of A component to B component is 1:(1-2), and the molar ratio of active hydrogen to epoxy group is 1.05-1.1; The A component comprises the following raw materials by mass fraction: epoxy resin 60-90 parts; epoxy active diluent 10-40 parts; The B component comprises the following raw materials by mass fraction: water-based epoxy curing agent 65-95 parts; water 5-35 parts; wetting agent 0.1-0.5 parts; defoaming agent 0.1-0.5 parts; the epoxy resin is E-44 epoxy resin, E-51 epoxy resin or E-55 epoxy resin; the epoxy value of the E-44 epoxy resin is 0.41-0.47mol / 100g; the epoxy value of the E-51 epoxy resin is 0.48-0.54mol / 100g; the epoxy value of the E-55 epoxy resin is 0.55-0.56mol / 100g; the epoxy active diluent is phenyl glycidyl ether, dodecyl to tetradecyl glycidyl ether, butyl glycidyl ether or polyethylene glycol diglycidyl ether; The water-based epoxy curing agent is a self-emulsifying nonionic water-based epoxy curing agent, with a solid content of 48-52wt%, a viscosity of 300-1300cps at a temperature of 23-27℃, and an active hydrogen equivalent of 200-300g / mol; The wetting agent is a nonionic alkyne diol modified surfactant; The defoaming agent is a star polymer composite mineral oil defoaming agent.

7. The substrate preparation method of claim 3, wherein: In step S3, the selected heat-conducting paint is a mixture of components A and B, and the mass ratio of component A to component B is 10:(0.8-1.2), and the molar ratio of active hydrogen to epoxy group is 0.8-0.9; Component A includes the following raw materials by mass fraction: Auxiliary agent 2.3-6.7 parts; Water 15-25 parts; Water-based epoxy emulsion 35-55 parts; Multi-walled carbon nanotube dispersion 0.5-2.5 parts; Flaky graphite powder 2-6 parts; Alumina powder 25-35 parts; Component B includes the following raw materials by mass fraction: Water-based epoxy curing agent 65-95 parts; Water 1-5 parts; Co-solvent 6-12 parts; The auxiliary agent includes the following raw materials by mass fraction: Wetting agent 0.1-0.5 parts; High molecular dispersant 0.5-1.2 parts; Ammonium salt dispersant 0.3-1 part; Defoaming agent 0.1-0.6 parts; Film-forming aid 0.8-2 parts; Thickening agent 0.6-2 parts; The wetting agent is a high HLB value nonionic isomeric alcohol polyoxyethylene ether wetting agent, with an HLB value of 17-18; The high molecular dispersant is a high molecular weight block copolymer solution containing pigment affinity groups; The ammonium salt dispersant is a hydrophobically modified ammonium salt acrylate copolymer dispersant; The defoaming agent is a silicone defoaming agent; The film-forming aid is dipropylene glycol butyl ether; The thickening agent is a medium-high shear polyurethane thickening agent; The aqueous epoxy emulsion is a non-ionic bisphenol A solid epoxy resin modified aqueous dispersion having a solid content of 48-52 wt%, an epoxy equivalent weight of 1000-1100 g / eq, a viscosity of 50-1000 cps at a temperature of 23-27 °C, and a density of 1.05-1.12 g / cm 3 ; The water-based epoxy curing agent is a self-emulsifying nonionic water-based epoxy curing agent, with a solid content of 51-53wt%, a viscosity of 2000-5000cps at a temperature of 23-27℃, and an active hydrogen equivalent of 210-250g / mol; The co-solvent is one or more of propylene glycol methyl ether, dipropylene glycol methyl ether, and ethylene glycol monobutyl ether; The room temperature thermal conductivity coefficient of the carboxyl-modified multi-walled carbon nanotube reaches 2800-3200W / (M•K); The room temperature thermal conductivity coefficient of the flaky graphite powder reaches 150-300W / (M•K); The room temperature thermal conductivity coefficient of the spherical alumina powder reaches 20-40W / (M•K).

8. A BIPV photovoltaic module, comprising the substrate of any one of claims 1-2, wherein the substrate is sequentially provided with a second encapsulating adhesive film layer, a photovoltaic cell module, a first encapsulating adhesive film layer, and a light-transmitting layer. ​ ​

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