A method for manufacturing white solar backsheet base film using a direct melting process

Abstract

This invention discloses a method for manufacturing a white solar backsheet base film using a direct melting method, relating to the field of solar energy technology. The base film includes steps such as: preparing a slurry, preparing a catalyst solution, preparing an esterified compound, preparing an additive melt, pre-polymerization, final polymerization, and molding. The white solar backsheet base film prepared in this application exhibits excellent resistance to light aging, hydrolysis, and water vapor barrier properties. Applying this white solar backsheet base film to a solar backsheet eliminates the need for a fluorine film coating or fluorine-containing resin coating, while still meeting the lifespan requirements of the solar backsheet. This helps reduce the cost of manufacturing solar backsheets and mitigates potential fluorine pollution after the solar backsheets are scrapped.

Description

Technical Field

[0001] This invention relates to the field of solar energy technology, and in particular to a method for manufacturing a white solar backsheet base film using a direct melting method. Background Technology

[0002] Solar panel backsheet base film is a polymer base film that is adhered to the backsheet of a solar panel to improve the stability of the solar panel's performance and extend its lifespan. During use, the solar panel backsheet base film is simply pressed onto the solar panel, and the film adheres firmly to the panel through van der Waltz forces.

[0003] In related technologies, there are two main types of solar backsheet base films: one is a coated backsheet base film, which involves coating a fluoropolymer resin onto the surface of a PET polyester film substrate; the other is an adhesive-coated composite backsheet base film, which involves laminating a fluoropolymer film onto the surface of a PET polyester film substrate. The function of the fluoropolymer resin layer or the fluoropolymer film is to form a protective film on the surface of the solar backsheet, making it more durable, light-resistant, heat-resistant, and corrosion-resistant, thus extending its service life.

[0004] However, since both types of solar backsheet base films contain fluorine, and fluorine pollution caused by fluorine compounds is an environmental problem that the whole society is facing, it is necessary to develop a fluorine-free solar backsheet base film to reduce fluorine pollution. Summary of the Invention

[0005] To reduce fluorine pollution caused by manufacturing solar backsheet base films, this application provides a method for manufacturing white solar backsheet base films using a direct melting method.

[0006] In a first aspect, this application provides a method for manufacturing a white solar backsheet base film using a direct melting method, employing the following technical solution:

[0007] A method for manufacturing a white solar backsheet base film using a direct melting process includes the following steps:

[0008] Slurry preparation: A slurry is obtained by mixing one of a dicarboxylic acid or a dimethyl ester of a dicarboxylic acid with a diol;

[0009] Preparation of catalyst solution: Dissolve the catalyst in diol to obtain catalyst solution;

[0010] Preparation of esterified products: Mix the slurry and catalyst solution, heat to 160-265℃ and react for 4-5 hours to obtain esterified products;

[0011] Preparation of additive melt: Inorganic particulate additives are melt-blended with polyester chips at 260-280℃ to obtain additive melt;

[0012] Prepolymerization: The esterified product and additive melt are mixed and subjected to prepolymerization reaction in a vacuum environment at 200-280℃. Then the excess diol is discharged to obtain the prepolymerization product.

[0013] Final polycondensation: The pre-polycondensation product is subjected to a polycondensation reaction in a vacuum environment at 280-285℃ to obtain the final polycondensation product;

[0014] Molding: The final polycondensation product is pumped into the die head, and after casting, cooling and molding, longitudinal stretching, transverse stretching, heat setting and corona treatment, a white solar backsheet base film is obtained.

[0015] By adopting the above technical solution, this application obtains a diol-based slurry through a slurry preparation step and a diol-based catalyst solution through a catalyst solution preparation step. This helps improve the compatibility of the slurry and catalyst solution in the esterification step, facilitating the catalytic reaction. Furthermore, before the pre-polymerization and final polymerization steps, inorganic particulate additives are prepared into an additive melt with polyester chips. By pre-preparing the additive melt, the inorganic particulate additives are not only fully dispersed before being added to the reactor, but also the large amount of ethylene glycol solution consumed in preparing inorganic particulate additives using solvent methods, as well as the temperature fluctuations and energy losses caused by adding a large amount of ethylene glycol to the reactor, are avoided. This results in a final polymerization product with uniformly dispersed inorganic particulate additives inside. This final polycondensation product can be used to prepare a white solar backsheet base film. This white solar backsheet base film has excellent resistance to light aging, hydrolysis and water vapor barrier properties. Applying this white solar backsheet base film to solar backsheets can also meet the requirements of the service life of solar backsheets, help reduce the cost of manufacturing solar backsheets, and reduce the fluorine pollution that may be caused after the solar backsheets are scrapped.

[0016] In one specific implementation, in the slurry preparation step, when a dicarboxylic acid and a diol are mixed, the molar ratio of the dicarboxylic acid to the diol is 1:1.15-1:1.7; when a dimethyl dicarboxylic acid ester and a diol are mixed, the molar ratio of the dimethyl dicarboxylic acid ester to the diol is 1:1.8-1:2.4; the dicarboxylic acid ester includes at least one of terephthalic acid and isophthalic acid; the dimethyl dicarboxylic acid ester includes at least one of ethylene terephthalate, ethylene isophthalate, and ethylene naphthalate; and the diol includes at least one of ethylene glycol, neopentyl glycol, propylene glycol, butanediol, and 1,4-cyclohexanediethanol.

[0017] By adopting the above technical solution, there are differences in the reaction between dicarboxylic acids and dimethyl dicarboxylic acids during their reaction with diols. Therefore, it is necessary to control the amount of dicarboxylic acids and dimethyl dicarboxylic acids used. This application has found through experiments that when selecting the specific components mentioned above, controlling the molar ratio of dicarboxylic acids to diols or the molar ratio of dimethyl dicarboxylic acids to diols within the aforementioned range allows the prepared slurry to undergo a good esterification reaction with the catalyst solution. The resulting white solar backsheet base film exhibits higher tensile strength and elongation at break, and lower thermal shrinkage. This indicates that within the aforementioned molar ratio range, the durability and heat resistance of the base film can be improved, helping to extend its service life.

[0018] In one specific implementation, in the catalyst liquid preparation step, the diol is ethylene glycol, and the diol and catalyst are mixed at a weight ratio of 100:(1-3) and dissolved at 175-188°C to obtain the catalyst liquid; when a dicarboxylic acid is used to mix with the diol, the catalyst is antimony trioxide; when a dimethyl dicarboxylic acid is used to mix with the diol, the catalyst is one or more of calcium acetate, cadmium acetate, zinc acetate, magnesium acetate, and cobalt acetate.

[0019] By adopting the above technical solution, when the above components are used to prepare the catalyst liquid, ethylene glycol and antimony trioxide can react to generate antimony glycolate at the above temperature. Using the above weight ratio, a catalyst liquid with a catalyst mass concentration of 1-5% can be prepared. This application has experimentally found that this catalyst liquid reacts well with the above slurry. The resulting base membrane, compared to base membranes coated with fluorinated resin or laminated with fluorine film, exhibits significantly reduced water vapor permeability, and the total irradiation in the 72-hour high-pressure cooking test and UV test reaches 180 kWh / m². 2 Even after that, it still has a high elongation at break, which indicates that using the above specific component ratio helps to improve the high temperature and high pressure resistance and light aging resistance of the base film.

[0020] In one specific implementation, in the esterification step, the slurry and catalyst liquid are mixed at a weight ratio of (87.5-98):(2-12.5).

[0021] Esterified compounds with an antimony content of 400-500 ppm in ethylene glycol can be prepared. Through experiments, this application found that maintaining the content within the above range helps to improve the tensile properties and elongation at break of the base film and reduce the thermal shrinkage rate.

[0022] In one specific implementation, in the additive melt preparation step, the inorganic particulate additive has a particle size of 0.1-0.7 μm, the weight ratio of the inorganic particulate additive to polyester chips is (4-50):100, and the inorganic particulate additive includes at least one of mica, barium sulfate, kaolin, titanium dioxide, calcium carbonate, silicon dioxide, talc and montmorillonite.

[0023] By adopting the above technical solution, when the particle size of the inorganic particulate additive is too small, its dispersibility in the melt is poor; when the particle size is too large, it affects the light transmittance and surface smoothness of the base film. Using inorganic particulate additives with the above-mentioned particle size and specific composition, and employing the above-mentioned weight ratio, can improve the dispersibility of the inorganic particulate additive in the melt. Simultaneously, it can control the light transmittance of the base film within the required range, thereby improving the light scattering properties and photoaging resistance of the base film, as well as enhancing its tensile strength and heat resistance.

[0024] In one specific implementation, in the pre-condensation step, the esterified compound and the additive melt are mixed to obtain a mixture, wherein the mass fraction of the additive melt in the mixture is 10%-30%, and the pre-condensation reaction is carried out at a vacuum degree of 1-10 kPa and a temperature of 270-280°C for 2-3 hours. Then, the excess diol is removed to obtain the pre-condensation product.

[0025] By adopting the above technical solution, the mass fraction of the additive melt is controlled within the above range, and the reaction conditions are controlled within the above range, which helps to improve the yield of the prepolymer. Moreover, the degree of polymerization of the prepolymer can be controlled within a more suitable range, thereby improving the fluidity of the prepolymer and facilitating its transport.

[0026] In one specific implementation, in the final polycondensation step, the pre-polycondensation product is subjected to a polycondensation reaction at a vacuum of 100-200 Pa and a temperature of 280-285 °C for 2-3 hours to obtain the final polycondensation product.

[0027] By adopting the above technical solution, when the prepolymer is prepared using the above process conditions, and then controlling the process conditions of the final polycondensation step within the above range, a final polycondensation product can be obtained. This final polycondensation product not only has excellent flowability and is easy to transport, but also has high tensile strength and elongation at break, low thermal shrinkage, low light transmittance and water vapor transmittance, good light scattering, and excellent high temperature and high pressure resistance and photoaging resistance of the base film.

[0028] In one specific implementation, the final polycondensation step further includes the following steps: mixing the final polycondensation product with an online thickener until homogeneous to obtain a final polycondensation melt, the quality indicators of which are as follows: intrinsic viscosity 0.80 dl / g-0.90 dl / g, terminal carboxyl group ≤20 mmol / t, melting point 250℃-272℃, ash content ≤0.06%; in the molding step, the final polycondensation melt is pumped into the die head.

[0029] By employing the above-mentioned technical solution, the addition of a large amount of inorganic particulate additives results in a high dynamic viscosity of the melt. This leads to a significant pressure drop during melt transport, making it difficult to convey. Therefore, it is not advisable to add thickeners during the pre-polymerization and final polymerization reactions. This application employs an online thickening process. After obtaining the final polymerization product, it is mixed with an online thickener, resulting in a rapid increase in melt viscosity. This ultimately yields a final polymerization melt that meets the high viscosity requirements of the backsheet base film. Therefore, this process not only facilitates material transport but also allows for the adjustment of the final polymerization melt to the desired viscosity, facilitating the production of the desired base film.

[0030] In one specific implementation, the mass fraction of the online thickener in the final polycondensation melt is 0.2%-3.0%, and the online thickener includes any one of oxazoline, isocyanate, pyromellitic anhydride, trimellitic anhydride, and glycidyl ether epoxy compounds.

[0031] By adopting the above technical solution, this application found through experiments that when the above-mentioned specific compounds are used as online tackifiers and the mass fraction of the online tackifier is controlled within the above range, the tensile strength of the final prepared base film is further increased, the thermal shrinkage rate and water vapor permeability are further reduced, and the high temperature and high pressure resistance is better.

[0032] Secondly, this application provides a white solar backsheet base film, which adopts the following technical solution:

[0033] A white solar backsheet base film, characterized in that it is prepared by the above-mentioned direct melting method for manufacturing white solar backsheet base film.

[0034] In summary, this application includes at least one of the following beneficial technical effects:

[0035] 1. The method of this application can prepare a fluorine-free white solar backsheet base film, and the white solar backsheet base film has excellent resistance to light aging, hydrolysis and water vapor blocking properties, which helps to reduce the cost of manufacturing solar backsheets and the fluorine pollution that may be caused after the solar backsheets are scrapped.

[0036] 2. The method of this application can further improve the performance of the base film in terms of light aging resistance, hydrolysis resistance and water vapor barrier by optimizing process conditions and raw material ratio;

[0037] 3. The method of this application can reduce the brittleness or warping of the base film and reduce the occurrence of stretching spots in the base film during the stretching process. Detailed Implementation

[0038] Unless otherwise specified, all raw materials used in the embodiments and comparative examples of this application were commercially available.

[0039] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0040] Example

[0041] Example 1

[0042] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method, comprising the following steps:

[0043] The slurry is prepared as follows: terephthalic acid and ethylene glycol are added to a pulping vessel at a weight ratio of 1:1.42, and the mixture is stirred and pulped until homogeneous to obtain the slurry.

[0044] The catalyst solution was prepared as follows: ethylene glycol and antimony trioxide were added to a preparation vessel at a weight ratio of 50:1 and stirred until homogeneous. The temperature inside the preparation vessel was then heated to 182°C to allow the reaction to proceed and obtain the catalyst solution.

[0045] The preparation of esterified products is carried out as follows: slurry and catalyst solution are added to esterification reactor at a weight ratio of 92.3:7.2, stirred until uniform, and the temperature inside the esterification reactor is heated to 205℃ and reacted at a constant temperature for 4.5h. Heating is then stopped to obtain esterified products.

[0046] The additive melt is prepared as follows: mica particles with a particle size of 0.1-0.7μm and PET chips are added to a screw extruder at a weight ratio of 27:100, and melted and blended at a temperature range of 260-280℃ to obtain the additive melt.

[0047] The prepolymerization reaction is carried out as follows: the esterified product and additive melt are introduced into the prepolymerization reactor at a mass ratio of 4:1 and mixed until homogeneous to obtain a mixture. The mass fraction of additive melt in the mixture is 20%. Then, the prepolymerization reactor is evacuated and heated. The reaction environment inside the prepolymerization reactor is maintained within a vacuum of 6±1 kPa and a temperature of 240±1 °C for 2.5 h. After the reaction is stopped, the excess diol in the prepolymerization reactor is discharged to obtain the prepolymerization product.

[0048] The final polycondensation reaction is carried out as follows: the pre-polycondensation product is introduced into the final polycondensation reactor, the reactor is evacuated and heated, and the reaction environment inside the reactor is maintained at a vacuum of 150±1 Pa and a temperature of 283±1℃ for 2.5 h. The reaction is then stopped to obtain the final polycondensation product.

[0049] The molding process is as follows: The final polycondensation product is pumped into the die head, and then the final polycondensation product is cast through the die head onto a cooling roller at 22.5℃ to obtain a cast sheet. At the same time, a back-wind device is used to blow air onto the side of the cast sheet away from the cooling roller. The air temperature is 17.5℃ and the wind speed is 12.5m / s. After cooling and molding, the cast sheet is sent to a longitudinal stretching machine. The cast sheet is first preheated at 80℃, and then heated to 100℃ by infrared heating. Then, it is stretched 3.3 times longitudinally. After longitudinal stretching, it is cooled and shaped at 23℃ to obtain a longitudinally stretched sheet. Then, the longitudinally stretched sheet is placed in an oven and preheated at 100℃. Then, the longitudinally stretched sheet is placed in a transverse stretching machine and stretched 3.4 times transversely at 115℃. After transverse stretching, a transverse sheet is obtained. The transverse sheet is high-temperature shaped at 215℃, then cooled and trimmed at 105℃. Finally, it is corona treated and wound up to obtain a white solar backsheet base film.

[0050] Example 2

[0051] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that an equal amount of isophthalic acid is used instead of terephthalic acid.

[0052] Example 3

[0053] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that an equal amount of neopentyl glycol is used instead of ethylene glycol.

[0054] Example 4

[0055] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that terephthalic acid and ethylene glycol are added to a pulping vessel at a weight ratio of 1:1.15, and the mixture is stirred and pulped until homogeneous to obtain a slurry.

[0056] Example 5

[0057] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that terephthalic acid and ethylene glycol are added to a pulping vessel at a weight ratio of 1:1.7, and the mixture is stirred and pulped until homogeneous to obtain a slurry.

[0058] Example 6

[0059] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that a slurry is prepared first. The operation is as follows: ethylene terephthalate and ethylene glycol are added to a pulping vessel at a weight ratio of 1:2.1, and the mixture is stirred and pulped until homogeneous to obtain the slurry.

[0060] Example 7

[0061] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 6 is that ethylene terephthalate and ethylene glycol are added to a pulping vessel at a weight ratio of 1:1.8, and the mixture is stirred and pulped until homogeneous to obtain a slurry.

[0062] Example 8

[0063] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 6 is that ethylene terephthalate and ethylene glycol are added to a pulping vessel at a weight ratio of 1:2.4, and the mixture is stirred and pulped until homogeneous to obtain a slurry.

[0064] Example 9

[0065] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 6 is that an equal amount of polyethylene isophthalate is used instead of polyethylene terephthalate.

[0066] Example 10

[0067] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that ethylene glycol and antimony trioxide are added to a preparation vessel at a weight ratio of 100:1, stirred until uniform, and the temperature inside the preparation vessel is heated to 188°C to react and obtain a catalyst solution.

[0068] Example 11

[0069] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that ethylene glycol and antimony trioxide are added to a preparation vessel at a weight ratio of 100:3, stirred until uniform, and the temperature inside the preparation vessel is heated to 175°C to react and obtain a catalyst solution.

[0070] Example 12

[0071] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that ethylene glycol and antimony trioxide are added to a preparation vessel at a weight ratio of 110:1, stirred until homogeneous, and the temperature inside the preparation vessel is heated to 190°C to react and obtain a catalyst solution.

[0072] Example 13

[0073] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that ethylene glycol and antimony trioxide are added to a preparation vessel at a weight ratio of 100:4, stirred until uniform, and the temperature inside the preparation vessel is heated to 173°C to react and obtain a catalyst solution.

[0074] Example 14

[0075] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that the slurry and catalyst liquid are added to the esterification reactor at a weight ratio of 87.5:12.5, stirred until uniform, and the temperature inside the esterification reactor is heated to 205°C and kept at a constant temperature for 4.5 hours. Heating is then stopped to obtain the esterified product.

[0076] Example 15

[0077] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that the slurry and catalyst liquid are added to the esterification vessel at a weight ratio of 98:2, stirred until uniform, and the temperature inside the esterification vessel is heated to 205°C and kept at a constant temperature for 4.5 hours. Heating is then stopped to obtain the esterified product.

[0078] Example 16

[0079] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that the slurry and catalyst liquid are added to the esterification vessel at a weight ratio of 92.3:7.2, stirred until uniform, and the temperature inside the esterification vessel is heated to 160°C and kept at a constant temperature for 5 hours. Heating is then stopped to obtain the esterified product.

[0080] Example 17

[0081] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that the slurry and catalyst liquid are added to the esterification vessel at a weight ratio of 92.3:7.2, stirred until uniform, and the temperature inside the esterification vessel is heated to 265°C and kept at a constant temperature for 4 hours. Heating is then stopped to obtain the esterified product.

[0082] Example 18

[0083] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that mica particles with a particle size of 0.1-0.7μm and PET chips are added to a screw extruder at a weight ratio of 1:25, and then melted and blended at a temperature range of 260-280℃ to obtain an additive melt.

[0084] Example 19

[0085] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that mica particles with a particle size of 0.1-0.7μm and PET chips are added to a screw extruder at a weight ratio of 1:2, and then melted and blended at a temperature range of 260-280℃ to obtain an additive melt.

[0086] Example 20

[0087] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that mica particles with a particle size of 0.05-0.1μm and PET chips are added to a screw extruder at a weight ratio of 1:23, and then melted and blended at a temperature range of 260-280℃ to obtain an additive melt.

[0088] Example 21

[0089] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that mica particles with a particle size of 0.7-1μm and PET chips are added to a screw extruder at a weight ratio of 1:1.8, and then melted and blended at a temperature range of 260-280℃ to obtain an additive melt.

[0090] Example 22

[0091] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that an equal amount of barium sulfate particles are used to replace mica particles.

[0092] Example 23

[0093] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that the esterified compound and additive melt are introduced into a prepolymerization reactor at a mass ratio of 9:1 and mixed until homogeneous to obtain a mixture. The mass fraction of the additive melt in the mixture is 10%. Then, the prepolymerization reactor is evacuated and heated. The reaction environment inside the prepolymerization reactor is maintained within a vacuum of 1±1 kPa and a temperature of 200±1 °C for 3 hours. After the reaction is stopped, the excess diol in the prepolymerization reactor is discharged to obtain the prepolymerization product.

[0094] Example 24

[0095] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that the esterified compound and additive melt are introduced into a prepolymerization reactor at a mass ratio of 7:3 and mixed until homogeneous to obtain a mixture. The mass fraction of the additive melt in the mixture is 30%. Then, the prepolymerization reactor is evacuated and heated. The reaction environment inside the prepolymerization reactor is maintained within a vacuum of 10±1 kPa and a temperature of 280±1 °C for 2 hours. After the prepolymerization reaction is stopped, the excess diol in the prepolymerization reactor is discharged to obtain the prepolymerization product.

[0096] Example 25

[0097] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that the esterified compound and additive melt are introduced into a prepolymerization reactor at a mass ratio of 6:4 and mixed until homogeneous to obtain a mixture. The mass fraction of the additive melt in the mixture is 40%. Then, the prepolymerization reactor is evacuated and heated. The reaction environment inside the prepolymerization reactor is maintained within a vacuum of 12±1 kPa and a temperature of 290±1 °C for 1.5 h. After the prepolymerization reaction is stopped, the excess diol in the prepolymerization reactor is discharged to obtain the prepolymerization product.

[0098] Example 26

[0099] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that the esterified compound and additive melt are introduced into a prepolymerization reactor at a mass ratio of 9.5:0.5 and mixed until homogeneous to obtain a mixture. The mass fraction of the additive melt in the mixture is 5%. Then, the prepolymerization reactor is evacuated and heated. The reaction environment inside the prepolymerization reactor is maintained within a vacuum of 0.5±1 kPa and a temperature of 190±1 °C for 3.5 hours. After the reaction is stopped, the excess diol in the prepolymerization reactor is discharged to obtain the prepolymerization product.

[0100] Example 27

[0101] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that the pre-condensation product is introduced into the final condensation reactor, the final condensation reactor is evacuated, and the final condensation reactor is heated. The reaction environment inside the final condensation reactor is maintained within the range of vacuum degree of 100±1Pa and temperature of 280±1℃ for 3 hours. After the reaction is stopped, the final condensation product is obtained.

[0102] Example 28

[0103] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that the pre-condensation product is introduced into the final condensation reactor, the final condensation reactor is evacuated, and the final condensation reactor is heated. The reaction environment inside the final condensation reactor is maintained within the range of vacuum degree of 200±1Pa and temperature of 285±1℃ for 2 hours. After the reaction is stopped, the final condensation product is obtained.

[0104] Example 29

[0105] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that the pre-condensation product is introduced into the final condensation reactor, the final condensation reactor is evacuated, and the final condensation reactor is heated. The reaction environment inside the final condensation reactor is maintained within the range of vacuum degree of 90±1Pa and temperature of 278±1℃ for 3.3 hours. After the reaction is stopped, the final condensation product is obtained.

[0106] Example 30

[0107] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that the pre-condensation product is introduced into the final condensation reactor, the final condensation reactor is evacuated, and the final condensation reactor is heated. The reaction environment inside the final condensation reactor is maintained within the range of vacuum degree of 210±1 Pa and temperature of 287±1℃ for 1.8 h for condensation reaction, and then the reaction is stopped to obtain the final condensation product.

[0108] Example 31

[0109] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that the pre-condensation product is introduced into the final condensation reactor, the final condensation reactor is evacuated, and the reactor is heated. The reaction environment inside the final condensation reactor is maintained within a vacuum of 150±1 Pa and a temperature of 283±1 °C for 2.5 h. After the reaction is stopped, the final condensation product is obtained. The final condensation product is then exported from the final condensation reactor. During the transportation of the final condensation product, oxazoline is added to the final condensation product. The weight ratio of oxazoline to the final condensation product is 1.5:98.5. After mixing evenly, the final condensation melt is obtained.

[0110] Example 32

[0111] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 31 is that, during the process of conveying the final polycondensation product, oxazoline is added to the final polycondensation product. The weight ratio of oxazoline to the final polycondensation product is 0.2:99.8. After mixing evenly, the final polycondensation melt is obtained.

[0112] Example 33

[0113] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 31 is that, during the process of conveying the final polycondensation product, oxazoline is added to the final polycondensation product. The weight ratio of oxazoline to the final polycondensation product is 3:97. After mixing evenly, the final polycondensation melt is obtained.

[0114] Example 34

[0115] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 31 is that an equal amount of isocyanate is used instead of oxazoline.

[0116] Example 35

[0117] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The only difference from Embodiment 1 is that the final polycondensation product is pumped into a die head, and then the final polycondensation product is cast through the die head onto a cooling roller at 15°C to obtain a cast sheet. At the same time, a back-wind device is used to blow air onto the side of the cast sheet away from the cooling roller. The air temperature is 5°C and the wind speed is 5 m / s. After cooling and forming, the cast sheet is sent to a longitudinal stretching machine. The cast sheet is first preheated at 70°C, and then heated to 90°C by infrared heating. Then, it is stretched 2.6 times longitudinally. After longitudinal stretching, it is cooled and shaped at 15°C to obtain a longitudinally stretched sheet. Then, the longitudinally stretched sheet is placed in an oven and preheated at 80°C. Then, the longitudinally stretched sheet is placed in a transverse stretching machine and stretched 2.8 times transversely at 90°C. After transverse stretching, a transverse sheet is obtained. The transverse sheet is subjected to high-temperature shaping treatment at 180°C, then cooled and trimmed at 30°C. Finally, it is wound up after corona treatment to obtain a white solar backsheet base film.

[0118] Example 36

[0119] This embodiment provides a method for manufacturing a white solar backsheet base film using a direct melting method. The difference from Embodiment 1 lies only in that the final polycondensation product is pumped into a die, and then the final polycondensation product is cast through the die onto a 30°C cooling roller to obtain a cast sheet. Simultaneously, a back-wind device is used to blow air onto the side of the cast sheet facing away from the cooling roller at a temperature of 30°C and a wind speed of 20 m / s. After cooling and shaping, the cast sheet is sent to a longitudinal stretching machine, where it is first preheated at 90°C, and then heated by infrared heating. The temperature is heated to 110℃, and then stretched 4.0 times longitudinally. After longitudinal stretching, it is cooled and shaped at 30℃ to obtain a longitudinally stretched sheet. The longitudinally stretched sheet is then placed in an oven and preheated at 120℃. The longitudinally stretched sheet is then placed in a transverse stretching machine and stretched 4.0 times transversely at 140℃. After transverse stretching, a transverse sheet is obtained. The transverse sheet is then subjected to high-temperature sizing treatment at 250℃, then cooled and trimmed at 180℃. Finally, it is corona treated and rolled up to obtain a white solar backsheet base film.

[0120] Comparative Example

[0121] Comparative Example 1

[0122] This comparative example provides a method for manufacturing a solar backsheet base film, comprising the following steps:

[0123] The preparation of the esterified product is carried out as follows: terephthalic acid, ethylene glycol and antimony trioxide are added to the esterification vessel in a weight ratio of 38.14:62.22:0.14, stirred until homogeneous, and the temperature inside the esterification vessel is heated to 205℃ and reacted at a constant temperature for 4.5 hours. Heating is then stopped to obtain the esterified product.

[0124] The additive melt is prepared as follows: mica particles with a particle size of 0.1-0.7μm and PET chips are added to a screw extruder at a weight ratio of 27:100, and melted and blended at a temperature range of 260-280℃ to obtain the additive melt.

[0125] The prepolymerization reaction is carried out as follows: the esterified product and additive melt are introduced into the prepolymerization reactor at a mass ratio of 4:1 and mixed until homogeneous to obtain a mixture. The mass fraction of additive melt in the mixture is 20%. Then, the prepolymerization reactor is evacuated and heated. The reaction environment inside the prepolymerization reactor is maintained within a vacuum of 6±1 kPa and a temperature of 240±1 °C for 2.5 h. After the reaction is stopped, the excess diol in the prepolymerization reactor is discharged to obtain the prepolymerization product.

[0126] The final polycondensation reaction is carried out as follows: the pre-polycondensation product is introduced into the final polycondensation reactor, the reactor is evacuated and heated, and the reaction environment inside the reactor is maintained at a vacuum of 150±1 Pa and a temperature of 283±1℃ for 2.5 h. The reaction is then stopped to obtain the final polycondensation product.

[0127] The molding process is as follows: The final polycondensation product is pumped into the die head, and then the final polycondensation product is cast through the die head onto a cooling roller at 13°C to obtain a cast sheet. At the same time, a back-wind device is used to blow air onto the side of the cast sheet away from the cooling roller. The air temperature is 4°C and the wind speed is 4m / s. After cooling and molding, the cast sheet is sent to a longitudinal stretching machine. The cast sheet is first preheated at 65°C, and then heated to 80°C by infrared heating. Then, it is stretched 3.3 times longitudinally. After longitudinal stretching, it is cooled and shaped at 13°C to obtain a longitudinally stretched sheet. Then, the longitudinally stretched sheet is placed in an oven and preheated at 70°C. Then, the longitudinally stretched sheet is placed in a transverse stretching machine and stretched 3.4 times transversely at 25°C. After transverse stretching, a transverse sheet is obtained. The transverse sheet is subjected to high-temperature shaping treatment at 175°C, and then cooled and trimmed at 25°C. Finally, it is corona treated and wound up to obtain a white solar backsheet base film.

[0128] Comparative Example 2

[0129] This comparative example provides a method for creating a solar backsheet base film, which includes the following steps:

[0130] The slurry is prepared as follows: terephthalic acid and ethylene glycol are added to a pulping vessel at a weight ratio of 1:1.42, and the mixture is stirred and pulped until homogeneous to obtain the slurry.

[0131] The catalyst solution was prepared as follows: ethylene glycol and antimony trioxide were added to a preparation vessel at a weight ratio of 50:1 and stirred until homogeneous. The temperature inside the preparation vessel was then heated to 182°C to allow the reaction to proceed and obtain the catalyst solution.

[0132] The preparation of esterified products is carried out as follows: slurry and catalyst solution are added to esterification reactor at a weight ratio of 92.3:7.2, stirred until uniform, and the temperature inside the esterification reactor is heated to 260℃ and reacted at a constant temperature for 4.5h. Heating is then stopped to obtain esterified products.

[0133] The prepolymerization reaction was carried out as follows: Esterified material, mica particles with a particle size of 0.1-0.7 μm, and PET chips were introduced into a prepolymerization reactor at a mass ratio of 4:0.21:0.79 and mixed until homogeneous to obtain a mixture. The mass fraction of the additive melt in the mixture was 20%. Then, the prepolymerization reactor was evacuated and heated. The reaction environment inside the prepolymerization reactor was maintained at a vacuum degree of 6±1 kPa and a temperature of 240±1 °C for 2.5 h. After that, the reaction was stopped, and the excess diol in the prepolymerization reactor was discharged to obtain the prepolymerization product.

[0134] The final polycondensation reaction is carried out as follows: the pre-polycondensation product is introduced into the final polycondensation reactor, the reactor is evacuated and heated, and the reaction environment inside the reactor is maintained at a vacuum of 150±1 Pa and a temperature of 283±1℃ for 2.5 h. The reaction is then stopped to obtain the final polycondensation product.

[0135] The molding process is as follows: The final polycondensation product is pumped into the die head, and then the final polycondensation product is cast through the die head onto a 35°C cooling roller to obtain a cast sheet. At the same time, a back-wind device is used to blow air onto the side of the cast sheet away from the cooling roller. The air temperature is 35°C and the wind speed is 22m / s. After cooling and molding, the cast sheet is sent to a longitudinal stretching machine. The cast sheet is first preheated at 95°C, and then heated to 120°C by infrared heating. Then, it is stretched 3.3 times longitudinally. After longitudinal stretching, it is cooled and shaped at 35°C to obtain a longitudinally stretched sheet. Then, the longitudinally stretched sheet is placed in an oven and preheated at 125°C. Then, the longitudinally stretched sheet is placed in a transverse stretching machine and stretched 3.4 times transversely at 145°C. After transverse stretching, a transverse sheet is obtained. The transverse sheet is high-temperature shaped at 255°C, then cooled and trimmed at 185°C. Finally, it is corona-treated and wound to obtain a white solar backsheet base film.

[0136] Comparative Example 3

[0137] This comparative example provides a method for providing a solar panel backsheet base film, which includes the following steps:

[0138] PET chips are added to a screw extruder and melted at a temperature range of 260-280℃. Then, they are extruded to obtain a PET polyester film. A 50μm thick organic fluorine epoxy resin layer is then coated on the surface of the PET polyester film. After curing, a white solar backsheet base film is obtained.

[0139] Performance testing

[0140] The following performance tests were performed on the base film samples prepared in Examples 1-36 and Comparative Examples 1-3:

[0141] Quality indicators of the final polycondensation product or the final polycondensation melt: The final polycondensation products of Examples 1-30, Examples 35-36 and Comparative Examples 1-3, and the final polycondensation melt of Examples 31-34 were tested. It was found that the quality indicators of the final polycondensation products of Examples 1-30, Examples 35-36 and Comparative Examples 1-3, and the final polycondensation melt of Examples 31-34 were all within the following ranges: intrinsic viscosity 0.80 dl / g-0.90 dl / g, terminal carboxyl group ≤20 mmol / kg, melting point 250℃-272℃, and ash content 1.0%-5.0%.

[0142] Morphology: The thickness of the base film samples was measured to be 275 μm using a digital micrometer. The test environment was 25℃ and 60% humidity. Then, the appearance of the base film samples was observed.

[0143] Tensile strength: The tensile strength of the base film sample shall be tested in accordance with the provisions of Chapter 11 of GB / T13542.2-2009, wherein the width of the strip is 15mm, the tensile speed is 100mm / min, and the spacing between the marks is 100mm. When there is no dispute, the clamping distance can also be 100mm.

[0144] Elongation at break: The elongation at break of the base film sample was tested according to Chapter 23 of GB / T13542.2-2009. The resolution of the measuring instrument was not less than 0.1 mm. The test conditions were: heating temperature of 150±2℃ and heating time of 30 min.

[0145] Heat shrinkage rate: The measuring instrument resolution shall not be less than 0.1 mm, as specified in Chapter 23 of GB / T13542.2-2009. Test conditions: heating temperature is 150 ± 2℃, heating time is 30 min.

[0146] Transmittance: The transmittance of the base film sample was measured using a transmittance meter at a wavelength of 400-1100 nm.

[0147] Water vapor transmission rate: The water vapor transmission rate of the base film sample was tested in a test environment with a temperature of (38±2)℃ and a relative humidity of (90±2)%.

[0148] High temperature and high pressure test: Test conditions: 121℃, 100% humidity, 0.2Mpa, aging for 48h and 72h.

[0149] UV aging test: Under ultraviolet light irradiation in the range of 280nm to 385nm, the total irradiation amount reached 180kwh / m 2 Then, its mechanical properties and yellowing were tested.

[0150] The test results are shown in Tables 1 and 2.

[0151] Table 1

[0152]

[0153]

[0154]

[0155]

[0156] Table 2

[0157]

[0158]

[0159] Combining Example 1 and Comparative Examples 1-3 with Table 1-2, it can be seen that compared to Example 1, Comparative Examples 1-2 all exhibit warped appearances, Comparative Examples 1-3 have lower tensile strength and elongation at break, higher thermal shrinkage rates, and excessively high light transmittance in Comparative Example 3. Furthermore, Comparative Examples 1-3 all showed brittle fracture after 72 hours of high-temperature and high-pressure aging, lower elongation at break after photoaging tests, and greater yellowing. This indicates that the preparation method and process conditions of Example 1 in this application help to simultaneously improve the mechanical properties, high-temperature and high-pressure resistance, and photoaging resistance of the base film, while reducing thermal shrinkage and water vapor transmittance. Moreover, compared to the fluorinated base film of Comparative Example 3, the base film of Example 1 in this application is fluorine-free, yet its performance remains superior.

[0160] As can be seen from Examples 1-9 and Tables 1-2, the various indicators of the base films in Examples 1-9 are relatively similar. This indicates that the base films in Examples 1-9 have good mechanical properties, high temperature and high pressure resistance, and light aging resistance. Within the process conditions of Examples 1-9, high-performance fluorine-free base films can be prepared.

[0161] Based on Examples 1 and 10-13 and Tables 1-2, it can be seen that compared with Example 1, the various indicators of the base film in Examples 10-11 did not change much, while the thermal shrinkage rate of the base film in Examples 12-13 increased significantly. Moreover, after high temperature and high pressure resistance tests and light aging resistance tests, the elongation at break of the base film in Examples 12-13 decreased significantly, while yellowing increased. This indicates that the performance of the base film can be further improved within the process conditions of Examples 1 and 10-11.

[0162] Based on Examples 1 and 14-17 and Tables 1-2, it can be seen that, compared with Example 1, the various indicators of the base membrane in Examples 14-17 are not significantly different. This indicates that using the above-mentioned weight ratio of slurry and catalyst liquid and esterification temperature both contribute to the preparation of high-performance fluorine-free base membranes.

[0163] Based on Examples 1 and 18-22 and Tables 1-2, it can be seen that compared with Example 1, the various indicators of Examples 18-19 and 22 are not significantly different. The base films of Examples 20-21 show worse mechanical properties and yellowing after high temperature and high pressure resistance tests and light aging resistance tests. This indicates that using the raw material ratios and types of raw materials of Examples 1, 18-19 and 22 can help to further improve the high temperature and high pressure resistance and light aging resistance of the base film.

[0164] Based on Examples 1 and 23-36, and in conjunction with Tables 1-2, it can be seen that, compared to Example 1, Examples 23-24, 27-28, and 31-36 exhibit higher tensile strength and elongation at break, lower thermal shrinkage, and better mechanical properties and yellowing resistance after high-temperature and high-pressure tests and light aging tests. In contrast, the base films of Examples 25-26 and 29-30 show poorer mechanical properties and yellowing resistance after these tests. This indicates that controlling the process conditions within the ranges of Examples 1, 23-24, 27-28, and 31-36 helps improve the high-temperature and high-pressure resistance and light aging resistance of the base film.

[0165] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for manufacturing a white solar backsheet base film using a direct melting method, characterized in that, Includes the following steps: Slurry preparation: A slurry is obtained by mixing one of a dicarboxylic acid or a dimethyl ester of a dicarboxylic acid with a diol; Preparation of catalyst solution: Dissolve the catalyst in diol to obtain catalyst solution; Preparation of esterified products: Mix the slurry and catalyst solution, heat to 160-265℃ and react for 4-5 hours to obtain esterified products; Preparation of additive melt: Inorganic particulate additives are melt-blended with polyester chips at 260-280℃ to obtain additive melt; the particle size of the inorganic particulate additives is 0.1-0.7μm, the weight ratio of inorganic particulate additives to polyester chips is (4-50):100, and the inorganic particulate additives include at least one of mica, barium sulfate, kaolin, titanium dioxide, calcium carbonate, silicon dioxide, talc and montmorillonite; Prepolymerization: The esterified product and the additive melt are mixed to obtain a mixture in which the mass fraction of the additive melt is 10%-30%. The prepolymerization reaction is carried out at a vacuum of 1-10 kPa and a temperature of 270-280℃ for 2-3 hours. Then the excess diol is removed to obtain the prepolymerization product. Final polycondensation: The pre-polycondensation product is subjected to a polycondensation reaction in a vacuum environment at 280-285℃ to obtain the final polycondensation product; Molding: The final polycondensation product is pumped into the die head, and after casting, cooling and molding, longitudinal stretching, transverse stretching, heat setting and corona treatment, a white solar backsheet base film is obtained.

2. The method for manufacturing a white solar backsheet substrate film using a direct melting method according to claim 1, characterized in that, In the pulping step, when a dicarboxylic acid and a diol are mixed, the molar ratio of the dicarboxylic acid to the diol is 1:1.15-1:1.7; when a dimethyl dicarboxylic acid ester and a diol are mixed, the molar ratio of the dimethyl dicarboxylic acid ester to the diol is 1:1.8-1:2.

4. The dicarboxylic acid includes at least one of terephthalic acid and isophthalic acid; the dimethyl dicarboxylic acid ester includes at least one of ethylene terephthalate, ethylene isophthalate, and ethylene naphthalate; and the diol includes at least one of ethylene glycol, neopentyl glycol, propylene glycol, butanediol, and 1,4-cyclohexanediethanol.

3. The method for manufacturing a white solar backsheet substrate film using a direct melting method according to claim 2, characterized in that, In the catalyst liquid preparation step, the diol is ethylene glycol. The diol and the catalyst are mixed at a weight ratio of 100:(1-3) and dissolved at 175-188°C to obtain the catalyst liquid. When a dicarboxylic acid is used to mix with a diol, the catalyst is antimony trioxide. When a dimethyl dicarboxylic acid is used to mix with a diol, the catalyst is one or more of calcium acetate, cadmium acetate, zinc acetate, magnesium acetate, and cobalt acetate.

4. The method for manufacturing a white solar backsheet base film using a direct melting method according to claim 3, characterized in that, In the esterification step, the slurry and catalyst liquid are mixed at a weight ratio of (87.5-98):(2-12.5).

5. The method for manufacturing a white solar backsheet substrate film using a direct melting method according to claim 1, characterized in that, In the final polycondensation step, the pre-polycondensation product is subjected to a polycondensation reaction at a vacuum of 100-200 Pa and a temperature of 280-285 °C for 2-3 hours to obtain the final polycondensation product.

6. The method for manufacturing a white solar backsheet substrate film using a direct melting method according to claim 5, characterized in that, The final polycondensation step further includes the following steps: mixing the final polycondensation product with an online thickener until homogeneous to obtain a final polycondensation melt. The quality indicators of the final polycondensation melt are as follows: intrinsic viscosity 0.80 dl / g-0.90 dl / g, terminal carboxyl group ≤20 mmol / t, melting point 250℃-272℃, ash content ≤0.06%; in the molding step, the final polycondensation melt is pumped into the die head.

7. The method for manufacturing a white solar backsheet base film using a direct melting method according to claim 6, characterized in that, The mass fraction of the online thickener in the final polycondensation melt is 0.2%-3.0%, and the online thickener includes any one of oxazoline, isocyanate, pyromellitic anhydride, trimellitic anhydride, and glycidyl ether epoxy compounds.

8. A white solar backsheet base film, characterized in that, The white solar backsheet base film is prepared by the direct melting method according to any one of claims 1-7.

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