High-transparency solar cell backboard base film and backboard film

Abstract

The invention discloses a transparent solar cell back panel base film and a back panel film, the transparent solar cell back panel base film is formed by blending thermoplastic polyester A, thermoplastic polyester B and a functional additive and then evaporating a layer of oxide, the functional additive is a mixture of nano-scale carbon nanotubes and nano-silica, and the functional additive is a mixture of nano-scale carbon nanotubes and nano-silica. Wherein the mass ratio of the carbon nano tube to the nano silicon dioxide is (1-3): (2-4). According to the invention, abundant cell structures are formed in the transparent solar cell backboard base film through a two-way stretching method, the cell structures provide abundant reflecting surfaces and refracting surfaces, the reflectivity of the solar cell backboard film is improved, and the surface temperature is reduced, so that the photoelectric conversion rate of a solar cell can be improved; the obtained solar cell back plate base film is bonded with a protective layer, so that the water resistance, the aging resistance and the weather resistance of the solar cell back plate film are improved, and the service life of the solar cell back plate film is prolonged.

Description

Technical Field

[0001] The present invention relates to a highly transparent base film for a solar cell backsheet and a backsheet film, which are mainly applied to the new energy field. Background Art

[0002] As a device that directly converts solar energy into electrical energy, solar cell modules have attracted much attention in terms of the use efficiency in natural resources and ecological protection, and a variety of solar cell modules have been developed. A solar cell is prepared by laminating tempered glass, silicon wafers, EVA glue, and a solar cell backsheet film. Since the solar cell is directly exposed to the air, it is vulnerable to the erosion of water vapor, acidic gases, high and low temperatures, ultraviolet rays, etc., resulting in the attenuation of the photoelectric conversion performance. The solar cell backsheet film plays a protective role for the EVA glue in the solar glass laminated battery panel, and can prevent water, insulate, resist aging, and support the battery chips.

[0003] However, the weather resistance, water resistance, insulation, and aging resistance of the existing backsheet films still need to be improved. They cannot ensure the reliable, stable, and long-term safe use of the battery, affect the performance and service life, and cannot reach the service life of 25 years, which will increase the maintenance cost in subsequent use. Therefore, there is an urgent need to propose a new solar cell backsheet film technology to solve the above problems. Summary of the Invention

[0004] In order to improve the water resistance, aging resistance, and weather resistance of the solar cell backsheet film, and further improve the conversion efficiency of the solar cell, the first aspect of the present invention provides a transparent base film for a solar cell backsheet. The transparent base film for a solar cell backsheet is obtained by blending a thermoplastic polyester A, a thermoplastic polyester B, and a functional additive, and then evaporating and depositing an oxide layer. The functional additive is a mixture of nanoscale carbon nanotubes and nanosilica, wherein the mass ratio of carbon nanotubes to nanosilica is (1-3):(2-4), and the addition amount of the functional additive is 0.5%-2% of the total mass of the thermoplastic polyester A and the thermoplastic polyester B, and then evaporating and depositing an oxide layer.

[0005] As a preferred embodiment, the intrinsic viscosity of the thermoplastic polyester A at 25°C is 0.5-0.85 dL / g.

[0006] Further preferably, the thermoplastic polyester A is selected from one or a combination of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polyarylate (PAR).

[0007] As a preferred embodiment, the intrinsic viscosity of the thermoplastic polyester B at 25°C is 0.65-0.9 dL / g.

[0008] More preferably, the thermoplastic polyester B is selected from one or more combinations of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polyarylate (PAR).

[0009] As a preferred embodiment, the oxide is selected from one of silicon dioxide, titanium dioxide, aluminum oxide, and zinc oxide.

[0010] More preferably, the average particle size of the oxide is 0.2 - 0.6 microns, and more preferably 0.3 - 0.5 microns.

[0011] More preferably, the shape of the oxide is spherical. Evaporating the oxide onto the surface of the polyester film can increase the reflectivity of the base film of the solar cell backplane, and within the preferred range, the oxide can be evenly evaporated onto the surface of the polyester film without particle aggregation.

[0012] The second aspect of the present invention provides a solar cell backplane film, which sequentially includes a first protective layer, a first adhesive layer, a transparent solar cell backplane base film, a second adhesive layer, and a second protective layer from top to bottom.

[0013] As a preferred embodiment, both the first protective layer and the second protective layer are formed by melt mixing a polymer, inorganic particles, and a UV absorber.

[0014] As a preferred embodiment, the polymer is selected from one of polyvinylidene chloride (PVDC), ethylene / vinyl alcohol copolymer (EVOH), polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, or polycarbonate (PC).

[0015] As a preferred embodiment, the UV absorber is selected from one of 2 - hydroxy - 4 - methoxybenzophenone, 2 - hydroxy - 4 - n - octoxybenzophenone, 2 - (2'-hydroxy - 3',5'-di - tert - phenyl)-5 - chlorobenzotriazole, and resorcinol monobenzoate.

[0016] As a preferred embodiment, the inorganic particles are selected from one or a combination of two of titanium dioxide, barium sulfate, zinc oxide, calcium carbonate, and silicon dioxide.

[0017] As a preferred embodiment, both the first adhesive layer and the second adhesive layer are selected from one of ethylene - vinyl acetate, polyvinyl butyral resin, epoxy resin, or polyurethane resin.

[0018] As a preferred embodiment, the thickness of the transparent solar cell backplane base film is 40 - 360 microns, the thicknesses of the first protective layer and the second protective layer are 20 - 50 microns respectively, and the thicknesses of the first adhesive layer and the second adhesive layer are 0.1 - 15 microns respectively.

[0019] The preparation method of the above-mentioned transparent solar cell backplane base film and backplane film is as follows:

[0020] (1) Thermoplastic polyester A, thermoplastic polyester B, and functional additives are dried at a drying temperature of 140°C to

[0021] 160°C for 2 h to 4 h, then extruded by an extruder at a temperature of 260°C to 290°C, and then made into a cast sheet by a cold drum at 15°C to 30°C. The cast sheet is first longitudinally stretched 2.5 to 3.5 times at 70°C to 80°C, then cooled to a temperature of 15°C to 20°C in 1 s to 3 s, and then transversely stretched

[0022] 2.5 to 3.5 times at 110°C to 130°C. The film after biaxial stretching enters the heat setting area of the electric heating channel. The temperatures of the setting area are as follows: the temperature of the first stage is 200 - 215°C, the temperature of the second stage is 215 - 230°C, and the temperature of the third stage is

[0023] 230 - 245°C. The heat setting time of the film is 100 s to 200 s. The film passing through the heat setting area is then cooled in two stages at 50°C to 65°C for 10 s to 35 s and at room temperature, and thus the polyester film is obtained;

[0024] (2) The polyester film obtained in step (1) is used to evaporate oxides through an optical vacuum coating machine, and the oxides are vapor-deposited on the polyester film to obtain a transparent solar cell backplane base film. The resistance temperature of the vacuum coating machine is 15 - 45°C, and the vacuum degree is 1.5×10 -3 Pa - 4×10 -3 Pa;

[0025] (3) Inorganic particles and UV absorbers are added to the polymer, mixed evenly, and fed into an extruder for melt mixing. The cast sheet is first longitudinally stretched 2.5 to 3.5 times at 70°C to 80°C, then cooled to a temperature of 15°C to 20°C in 1 s to 3 s, and then transversely stretched 2.5 to 3.5 times at 110°C to 130°C to obtain a first protective layer and a second protective layer;

[0026] (4) The upper surface of the transparent solar cell backplane base film obtained in step (2) is coated with a first adhesive layer in an oven, and the other side of the first adhesive layer is compounded with the first protective layer. The lower surface of the transparent solar cell backplane base film is coated with a second adhesive layer, and the other side of the second adhesive layer is compounded with the second protective layer. The oven temperature is 85 - 125°C, and the reaction time is 100 - 250 s.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) Through biaxial stretching, a rich cell structure is formed in the base film of the solar cell backplane. The interfaces of this cell structure can increase the reflection surface and refraction surface, resulting in an increase in the reflectivity of the solar cell backplane film, a reduction in the surface temperature of the solar cell, and thus an improvement in the photoelectric conversion efficiency of the solar cell.

[0029] (2) Bonding the obtained transparent base film of the solar cell backplane with a protective layer can improve the waterproofness, anti-aging property, and weather resistance of the solar cell backplane film, and increase the service life of the solar cell backplane film. Description of the Drawings

[0030] Figure 1 is a highly transparent base film of the solar cell backplane.

[0031] Figure 2 is the solar cell backplane film.

[0032] Reference Numerals: 1. Polyester film; 2. Oxide; 3. First protective layer; 4. First adhesive layer; 5. Second adhesive layer; 6. Second protective layer; Detailed Embodiments

[0033] To solve the above problems, a first aspect of the present invention provides a highly transparent base film of the solar cell backplane. The transparent base film of the solar cell backplane is formed by blending thermoplastic polyester A, thermoplastic polyester B, and a functional additive, and then vapor-depositing an oxide layer.

[0034] As a preferred embodiment, the intrinsic viscosity of thermoplastic polyester A at 25 °C is 0.5 - 0.85 dL / g.

[0035] Further preferably, thermoplastic polyester A is selected from one or a combination of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polyarylate (PAR).

[0036] As a preferred embodiment, the intrinsic viscosity of thermoplastic polyester B at 25 °C is 0.65 - 0.9 dL / g.

[0037] Further preferably, thermoplastic polyester B is selected from one or a combination of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polyarylate (PAR).

[0038] As a preferred embodiment, the oxide is selected from one of silicon dioxide, titanium dioxide, aluminum oxide, and zinc oxide.

[0039] Further preferably, the average particle size of the oxide is 0.2 - 0.6 microns, more preferably 0.3 - 0.5 microns.

[0040] Further preferably, the shape of the oxide is spherical. Evaporating the oxide onto the surface of the polyester film can improve the reflectivity of the base film of the solar cell backplane, and within the preferred range, the oxide can be evenly evaporated onto the surface of the polyester film without particle aggregation.

[0041] As a preferred embodiment, thermoplastic polyester A accounts for 60% - 90% of the transparent solar cell backplane base film; thermoplastic polyester B accounts for 10% - 40% of the transparent solar cell backplane base film; the oxide accounts for 5% - 10% of the transparent solar cell backplane base film;

[0042] The second aspect of the present invention provides a solar cell backplane film, which sequentially includes a first protective layer, a first adhesive layer, a transparent solar cell backplane base film, a second adhesive layer, and a second protective layer from top to bottom.

[0043] As a preferred embodiment, both the first protective layer and the second protective layer are formed by melting and mixing a polymer, inorganic particles, and a UV absorber.

[0044] As a preferred embodiment, the polymer is selected from one of polyvinylidene chloride (PVDC), ethylene / vinyl alcohol copolymer (EVOH), polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, or polycarbonate (PC).

[0045] As a preferred embodiment, the UV absorber is selected from one of 2 - hydroxy - 4 - methoxybenzophenone, 2 - hydroxy - 4 - n - octoxybenzophenone, 2 - (2'-hydroxy - 3',5'-diphenyl)-5 - chlorobenzotriazole, or resorcinol monobenzoate.

[0046] As a preferred embodiment, the inorganic particles are selected from one or a combination of two of titanium dioxide, barium sulfate, zinc oxide, calcium carbonate, and silicon dioxide.

[0047] As a preferred embodiment, both the first adhesive layer and the second adhesive layer are selected from one of ethylene - vinyl acetate, polyvinyl butyral resin, epoxy resin, or polyurethane resin.

[0048] The polymer accounts for 60% - 90% of the protective layer; the inorganic particles account for 10% - 20% of the protective layer; the UV absorber accounts for 1% - 5% of the protective layer;

[0049] As a preferred embodiment, the thickness of the transparent solar cell backplane base film is 40 - 360 microns, the thicknesses of the two protective layers are 20 - 50 microns respectively, and the thicknesses of the two adhesive layers are 0.1 - 15 microns respectively.

[0050] The preparation methods of the above-mentioned transparent solar cell backplane base film and backplane film are as follows:

[0051] (1) Thermoplastic polyester A, thermoplastic polyester B, and functional additives are dried at a drying temperature of 140°C to 160°C for 2 h to 4 h, then extruded by an extruder at a temperature of 260°C to 290°C, and then made into a cast sheet by a cold drum at 15°C to 30°C. The cast sheet is first longitudinally stretched 2.5 to 3.5 times at 70°C to 80°C, then cooled to a temperature of 15°C to 20°C in 1 s to 3 s, and then transversely stretched

[0052] 2.5 to 3.5 times. The film after biaxial stretching enters the heat setting area of the electric heating channel. The temperatures of the setting area are as follows: the temperature of the first stage is 200 - 215°C, the temperature of the second stage is 215 - 230°C, and the temperature of the third stage is

[0053] 230 - 245°C. The heat setting time of the film is 100 s to 200 s. The film passing through the heat setting area is cooled in two stages at 50°C to 65°C for 10 s to 35 s and at room temperature, and then the polyester film is obtained;

[0054] (2) The polyester film obtained in step (1) is evaporated with an oxide by an optical vacuum coating machine, and the oxide is deposited on the polyester film to obtain a transparent solar cell backplane base film. The resistance temperature of the vacuum coating machine is

[0055] 15 - 45°C, and the vacuum degree is 1.5×10 -3 Pa - 4×10 -3 Pa;

[0056] (3) Inorganic particles and a UV absorber are added to a polymer, mixed evenly, and fed into an extruder for melt mixing. The cast sheet is first longitudinally stretched 2.5 to 3.5 times at 70°C to 80°C, then cooled to a temperature of 15°C to 20°C in 1 s to 3 s, and then transversely stretched 2.5 to 3.5 times to obtain a first protective layer and a second protective layer;

[0057] (4) The upper surface of the transparent solar cell backplane base film obtained in step (2) is coated with a first adhesive layer in an oven, the other side of the first adhesive layer is compounded with the first protective layer, the lower surface of the transparent solar cell backplane base film is coated with a second adhesive layer, and the other side of the second adhesive layer is compounded with the second protective layer. The oven temperature is 85 - 125°C, and the reaction time is 100 - 250 s.

[0058] The present invention will be specifically described below through embodiments. It is necessary to point out here that the following embodiments are only used to further illustrate the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention above still fall within the protection scope of the present invention.

[0059] In addition, if there is no other description, the raw materials used are all commercially available.

[0060] Example 1

[0061] A transparent base film for a solar cell backplane, the transparent base film for a solar cell backplane is made of thermoplastic polyester A, thermoplastic polyester B, functional additives, and then an oxide is vapor-deposited.

[0062] A method for preparing a base film for a solar cell backplane, comprising the following steps:

[0063] (1) 85 parts by weight of polyethylene terephthalate (PET) with an intrinsic viscosity of 0.8 dL / g, 10 parts by weight of polyethylene terephthalate (PET) with an intrinsic viscosity of 0.7 dL / g, and functional additives are dried at a drying temperature of 150 °C for 3 h, then extruded through an extruder at a temperature of 280 °C, and then made into a cast sheet through a 20 °C cold drum. The cast sheet is first longitudinally stretched 3 times at 75 °C, then cooled to a temperature of 18 °C in 2 s, and then transversely stretched 3 times at 120 °C. The biaxially stretched film enters the heat setting zone of the electric heating channel. The temperatures of the setting zone are: the temperature of the first stage is 210 °C, the temperature of the second stage is 220 °C, and the temperature of the third stage is 240 °C. The heat setting time of the film is 150 s. The film passing through the heat setting zone is cooled in two stages at 60 °C for 25 s and at room temperature to obtain a polyester film;

[0064] (2) 5 parts by weight of titanium dioxide is evaporated on the polyester film obtained in step (1) through an optical vacuum coating machine, and the titanium dioxide is vapor-deposited on the polyester film to obtain a transparent base film for a solar cell backplane. The temperature of the vacuum coating machine is 35 °C, and the vacuum degree is 3×10 -3 Pa.

[0065] The thickness of the transparent base film for a solar cell backplane is 280 microns.

[0066] A solar cell backplane film, which sequentially includes a first protective layer, a first adhesive layer, a transparent base film for a solar cell backplane, a second adhesive layer, and a second protective layer from top to bottom.

[0067] A method for preparing a solar cell backplane film, comprising the following steps:

[0068] (1) Add 10 parts by weight of zinc oxide and 5 parts by weight of 2-hydroxy-4-methoxybenzophenone to 85 parts by weight of polyvinylidene chloride, mix evenly, and feed the mixture into an extruder for melt mixing. Extrude the mixture through the extruder at a temperature of 280 °C, and then form a cast film using a 20 °C cold drum. First, longitudinally stretch the cast film 3 times at 75 °C, then cool it to 18 °C in 2 s, and then transversely stretch it 3 times at 120 °C to obtain a protective layer;

[0069] (2) Coat the upper surface of the above-mentioned transparent solar cell backplane base film with a first adhesive layer in an oven, and compound the other side of the first adhesive layer with a first protective layer. Coat the lower surface of the transparent solar cell backplane base film with a second adhesive layer, and compound the other side of the second adhesive layer with a second protective layer. Obtain the solar cell backplane film. The oven temperature is 110 °C, and the reaction time is 200 s.

[0070] The thickness of the protective layer is 40 microns; the thickness of the adhesive layer is 10 microns.

[0071] Example 2

[0072] A transparent solar cell backplane base film, which is obtained by blending a thermoplastic polyester A, a thermoplastic polyester B, and a functional additive, and then evaporating a layer of oxide.

[0073] A method for preparing a transparent solar cell backplane base film, comprising the following steps:

[0074] (1) Mix 75 parts by weight of polyethylene terephthalate (PET) with an intrinsic viscosity of 0.76 dL / g, 20 parts by weight of polybutylene terephthalate (PBT) with an intrinsic viscosity of 0.65 dL / g, and a functional additive at a drying temperature of 150 °C for 3 h. Then extrude the mixture through an extruder at a temperature of 280 °C, and then form a cast film using a 20 °C cold drum. First, longitudinally stretch the cast film 3 times at 75 °C, then cool it to 18 °C in 2 s, and then transversely stretch it 3 times at 120 °C. The film after biaxial stretching enters the heat setting zone of an electric heating channel. The temperatures of the setting zone are as follows: the temperature of the first stage is 210 °C, the temperature of the second stage is 220 °C, and the temperature of the third stage is 240 °C. The heat setting time of the film is 150 s. The film passing through the heat setting zone is then cooled in two stages at 60 °C for 25 s and at room temperature to obtain a polyester film; (2) Evaporate 5 parts by weight of silicon dioxide on the polyester film obtained in step 1

[0075] Deposit the silicon dioxide on the polyester film to obtain a transparent solar cell backplane base film. The temperature of the vacuum coating machine is 35 °C, and the vacuum degree is 3×10 -3 Pa.

[0076] The thickness of the transparent solar cell backplane base film is 280 microns.

[0077] A solar cell backplane film, which sequentially includes a first protective layer, a first adhesive layer, a transparent solar cell backplane base film, a second adhesive layer, and a second protective layer from top to bottom.

[0078] A method for preparing a solar cell backplane film includes the following steps:

[0079] (1) Add 15 parts by weight of calcium carbonate and 2.5 parts by weight of 2-hydroxy-4-n-octyloxybenzophenone to 82.5 parts by weight of ethylene / vinyl alcohol copolymer (EVOH), mix evenly and feed into an extruder for melt mixing. Extrude through the extruder at a temperature of 280 °C, and then form a cast sheet through a 20 °C cold drum. The cast sheet is first longitudinally stretched 3 times at 75 °C, then cooled to a temperature of 18 °C in 2 s, and then transversely stretched 3 times at 120 °C to obtain a protective layer after biaxial stretching;

[0080] (2) Coat the upper surface of the above-mentioned transparent solar cell backplane base film with a first adhesive layer in an oven, and compound the other side of the first adhesive layer with the first protective layer. Coat the lower surface of the transparent solar cell backplane base film with a second adhesive layer, and compound the other side of the second adhesive layer with the second protective layer to obtain the solar cell backplane film. The oven temperature is 110 °C and the reaction time is 200 s.

[0081] The thickness of the protective layer is 40 microns; the thickness of the adhesive layer is 10 microns.

[0082] Example 3

[0083] A transparent solar cell backplane base film, which is formed by blending thermoplastic polyester A, thermoplastic polyester B, and a functional additive, and then evaporating a layer of oxide.

[0084] A method for preparing a solar cell backplane base film includes the following steps:

[0085] (1) 65 parts by weight of polyethylene terephthalate (PET) with an intrinsic viscosity of 0.7 dL / g, 25 parts by weight of polyethylene naphthalate (PEN) with an intrinsic viscosity of 0.8 dL / g, and functional additives are dried at 150 °C for 3 h, then extruded by an extruder at 280 °C, and then made into a cast film through a 20 °C cold drum. The cast film is first longitudinally stretched 3 times at 75 °C, then cooled to 18 °C in 2 s, and then transversely stretched 3 times at 120 °C. The biaxially stretched film enters the heat setting zone of the electric heating channel. The temperatures of the setting zone are as follows: the temperature of the first stage is 210 °C, the temperature of the second stage is 220 °C, and the temperature of the third stage is 240 °C. The heat setting time of the film is 150 s. The film passing through the heat setting zone is cooled in two stages at 60 °C for 25 s and at room temperature to obtain a polyester film;

[0086] (2) 10 parts by weight of aluminum oxide is evaporated onto the polyester film obtained in step (1) through an optical vacuum coating machine to obtain a transparent solar cell backplane base film. The temperature of the vacuum coating machine is 35 °C, and the vacuum degree is 3×10-3 Pa.

[0087] The thickness of the transparent solar cell backplane base film is 280 microns.

[0088] A solar cell backplane film includes, from top to bottom, a first protective layer, a first adhesive layer, a transparent solar cell backplane base film, a second adhesive layer, and a second protective layer.

[0089] A preparation method of a solar cell backplane base film includes the following steps:

[0090] (1) 20 parts by weight of barium sulfate and 5 parts by weight of resorcinol monobenzoate are added to 75 parts by weight of polyethylene terephthalate, mixed evenly, and fed into an extruder for melt mixing. Then it is extruded by the extruder at 280 °C, and then made into a cast film through a 20 °C cold drum. The cast film is first longitudinally stretched 3 times at 75 °C, then cooled to 18 °C in 2 s, and then transversely stretched 3 times at 120 °C to obtain a protective layer after biaxial stretching;

[0091] (2) Epoxy resin is coated on the upper and lower surfaces of the above-mentioned transparent solar cell backplane base film in an oven, and the upper and lower surfaces are respectively compounded with the protective layer to obtain the solar cell backplane film. The oven temperature is 110 °C, and the reaction time is 200 s.

[0092] The thickness of the protective layer is 40 microns; the thickness of the adhesive layer is 10 microns.

[0093] Comparative Example 1:

[0094] A transparent solar cell backplane base film, which is formed by blending thermoplastic polyester A and thermoplastic polyester B and then evaporating an oxide layer.

[0095] A method for preparing a solar cell backplane base film includes the following steps:

[0096] (1) 85 parts by weight of polyethylene terephthalate (PET) with an intrinsic viscosity of 0.8 dL / g is dried at a drying temperature of 150 °C for 3 h, then extruded by an extruder at a temperature of 280 °C, and then formed into a cast sheet by a 20 °C cold drum. The cast sheet is first longitudinally stretched 3 times at 75 °C, then cooled to a temperature of 18 °C in 2 s, and then transversely stretched 3 times at 120 °C. The biaxially stretched film enters the heat setting zone of the electric heating channel. The temperatures of the setting zone are as follows: the temperature of the first stage is 210 °C, the temperature of the second stage is 220 °C, and the temperature of the third stage is 240 °C. The heat setting time of the film is 150 s. The film passing through the heat setting zone is cooled in two stages at 60 °C for 25 s and at room temperature to obtain a polyester film;

[0097] (2) 15 parts by weight of titanium dioxide is evaporated onto the polyester film obtained in step (1) by an optical vacuum coating machine to obtain a transparent solar cell backplane base film. The temperature of the vacuum coating machine is 35 °C, and the vacuum degree is 3×10-3 Pa.

[0098] The thickness of the transparent solar cell backplane base film is 280 microns.

[0099] A solar cell backplane film includes, from top to bottom, a first protective layer, a first adhesive layer, a transparent solar cell backplane base film, a second adhesive layer, and a second protective layer.

[0100] A method for preparing a solar cell backplane film includes the following steps:

[0101] (1) 10 parts by weight of zinc oxide and 5 parts by weight of 2-hydroxy-4-methoxybenzophenone are added to 85 parts by weight of polyvinylidene chloride, mixed evenly and fed into an extruder for melt mixing, extruded by the extruder at a temperature of 280 °C, and then formed into a cast sheet by a 20 °C cold drum. The cast sheet is first longitudinally stretched 3 times at 75 °C, then cooled to a temperature of 18 °C in 2 s, and then transversely stretched 3 times at 120 °C to obtain a protective layer after biaxial stretching;

[0102] (2) The upper surface of the above-mentioned transparent solar cell backplane base film is coated with a first adhesive layer in an oven, and the other side of the first adhesive layer is compounded with the first protective layer. The lower surface of the transparent solar cell backplane base film is coated with a second adhesive layer, and the other side of the second adhesive layer is compounded with the second protective layer. The solar cell backplane film is obtained. The oven temperature is 110 °C, and the reaction time is 200 s.

[0103] The thickness of the protective layer is 40 microns; the thickness of the adhesive layer is 10 microns.

[0104] Comparative Example 2:

[0105] A transparent solar cell backplane base film, which is prepared by blending and reacting thermoplastic polyester A and thermoplastic polyester B.

[0106] A method for preparing a solar cell backplane base film, comprising the following steps:

[0107] (1) 85 parts by weight of polyethylene terephthalate (PET) with an intrinsic viscosity of 0.8 dL / g and 15 parts by weight of polyethylene terephthalate (PET) with an intrinsic viscosity of 0.7 dL / g are dried at a drying temperature of 150 °C for 3 h, then extruded by an extruder at a temperature of 280 °C, and then made into a cast film by a 20 °C cold drum. The cast film is first longitudinally stretched 3 times at 75 °C, then cooled to a temperature of 18 °C in 2 s, and then transversely stretched 3 times at 120 °C. The film after biaxial stretching enters the heat setting zone of the electric heating channel. The temperatures of the setting zone are: the temperature of the first stage is 210 °C, the temperature of the second stage is 220 °C, and the temperature of the third stage is 240 °C. The heat setting time of the film is 150 s. The film passing through the heat setting zone is cooled in two stages at 60 °C for 25 s and at room temperature to obtain a transparent solar cell backplane base film.

[0108] The thickness of the transparent solar cell backplane base film is 280 microns.

[0109] A solar cell backplane film, which sequentially includes a first protective layer, a first adhesive layer, a transparent solar cell backplane base film, a second adhesive layer, and a second protective layer from top to bottom.

[0110] A method for preparing a solar cell backplane film, comprising the following steps:

[0111] (1) 10 parts by weight of zinc oxide and 5 parts by weight of 2-hydroxy-4-methoxybenzophenone are added to 85 parts by weight of polyvinylidene chloride, mixed evenly and fed into an extruder for melt mixing, extruded by the extruder at a temperature of 280 °C, and then made into a cast film by a 20 °C cold drum. The cast film is first longitudinally stretched 3 times at 75 °C, then cooled to a temperature of 18 °C in 2 s, and then transversely stretched 3 times at 120 °C to obtain a protective layer after biaxial stretching;

[0112] (2) Coating the upper surface of the above-mentioned transparent solar cell backplane base film with a first adhesive layer in an oven, and compounding the other side of the first adhesive layer with a first protective layer. Coating the lower surface of the transparent solar cell backplane base film with a second adhesive layer, and compounding the other side of the second adhesive layer with a second protective layer. Obtain the solar cell backplane film. The oven temperature is 110 °C, and the reaction time is 200 s.

[0113] The thickness of the protective layer is 40 microns; the thickness of the adhesive layer is 10 microns.

[0114] Performance test:

[0115] 1. Reflectance: According to the provisions of GB / T 3979-2008, under the condition of D55 light source, through the integrating sphere d / 8°

[0116] The reflectance of the solar cell backplane film prepared by the structure test is the weighted average of the reflectances at wavelengths of 380-780 nm every 10 nm, and the weight values correspond to the energy distribution curve of the D55 light source.

[0117] 2. Water vapor transmission rate: According to the provisions of GB / T 1037-1988, in an environment of 30 °C and 95% RH, use a TSY-W2 water vapor transmission rate tester to test the prepared solar cell backplane film.

[0118] 3. Yellowing value: The yellowing value after being irradiated with 280 kwh / m by a UVB-313 ultraviolet lamp 2 energy.

[0119] The performance tests of reflectance, water vapor transmission rate, and yellowing value were carried out on the examples and comparative examples. The results are shown in Table 1.

[0120] Table 1

[0121]

[0122] The above is only the preferred embodiment of the present invention, and it is not a limitation of the invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or equivalent changes to equivalent embodiments, but as long as they do not depart from the technical content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims

1. A highly transparent base film for a solar cell backplane, characterized in that, The described transparent solar cell backplane base film is formed by blending thermoplastic polyester A, thermoplastic polyester B, and a functional additive, and then vapor-depositing an oxide layer. The functional additive is a mixture of nanoscale carbon nanotubes and nano-silica, where the mass ratio of carbon nanotubes to nano-silica is (1 - 3):(2 - 4), and the addition amount of the functional additive is 0.5% - 2% of the total mass of thermoplastic polyester A and thermoplastic polyester B.

2. The highly transparent solar cell backplane base film according to claim 1, wherein Thermoplastic polyester A is selected from one or a combination of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polyarylate. The intrinsic viscosity of thermoplastic polyester A at 25°C is 0.5 - 0.85 dL / g.

3. The highly transparent solar cell backplane base film according to claim 1, wherein Thermoplastic polyester B is selected from one or a combination of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polyarylate. The intrinsic viscosity of thermoplastic polyester B at 25°C is 0.65 - 0.9 dL / g.

4. The highly transparent solar cell backplane base film according to claim 1, characterized in that The oxide is selected from one of silicon dioxide, titanium dioxide, aluminum oxide, and zinc oxide.

5. A backsheet film for a solar cell, characterized in that, It sequentially includes a first protective layer, a first adhesive layer, the highly transparent solar cell backplane base film according to any one of claims 1 - 4, a second adhesive layer, and a second protective layer from top to bottom.

6. The backsheet film for a solar cell according to claim 5, wherein Both the first protective layer and the second protective layer are formed by melt - mixing a polymer, inorganic particles, and a UV absorber.

7. The solar cell backplane film according to claim 5, wherein, The polymer is selected from one of polyvinylidene chloride, ethylene / vinyl alcohol copolymer, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, or polycarbonate.

8. The solar cell backplane film according to claim 5, characterized in that, The UV absorber is selected from one of 2 - hydroxy - 4 - methoxybenzophenone, 2 - hydroxy - 4 - n - octoxybenzophenone, 2-(2'-hydroxy - 3',5'-diphenyl)-5 - chlorobenzotriazole, and resorcinol monobenzoate.

9. The solar cell backplane film according to claim 5, characterized in that, Both the first adhesive layer and the second adhesive layer are selected from one of ethylene - vinyl acetate, polyvinyl butyral resin, epoxy resin, or polyurethane resin.

10. The backsheet film for a solar cell according to claim 5, wherein The thickness of the transparent solar cell backplane base film is 40 - 360 microns, the thicknesses of the first protective layer and the second protective layer are 20 - 50 microns respectively, and the thicknesses of the first adhesive layer and the second adhesive layer are 5 - 15 microns respectively.

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