A BOPET film for photovoltaic backsheet and preparation method thereof

Abstract

The present invention provides a BOPET film for photovoltaic backboard and a preparation method thereof, and relates to the technical field of plastic film production and processing. The film comprises a polyester core layer and a polyester surface layer; the polyester surface layer comprises the following components by weight: 10-15 parts of an opening masterbatch; 65-80 parts of a polyester slice; 10-20 parts of an anti-ultraviolet functional masterbatch; the polyester core layer comprises the following components: 5-10 parts of an anti-ultraviolet functional masterbatch; 90-95 parts of a polyester slice; the anti-ultraviolet functional masterbatch comprises the following components: 1020 parts of terephthalic acid; 560 parts of ethylene glycol; 1.0 parts of antimony trioxide; 0.8 parts of trimethyl phosphate; 20 parts of an anti-ultraviolet protective agent; and 140-180 parts of an anti-ultraviolet agent. The BOPET film for photovoltaic backboard provided by the present invention selects a specific anti-ultraviolet functional masterbatch in the polyester surface layer and the polyester core layer, and solves the problem that the anti-ultraviolet performance of the BOPET polyester film is weak and the weather resistance performance is poor.

Description

Technical Field

[0001] The invention relates to the technical field of plastic film production and processing, and in particular to a BOPET film for a photovoltaic backboard and a preparation method thereof. Background Art

[0002] Photovoltaic backsheet is also called solar cell backsheet. As the photovoltaic encapsulation material on the back of solar cell modules, it can effectively protect solar cell modules from the erosion of EVA film, solar cells and other materials by environmental factors such as light, moisture and heat in outdoor environments, and play the role of insulation and weather protection. Since the photovoltaic backsheet is located at the outermost layer on the back of the photovoltaic module, it is in direct contact with the external environment over a large area, and it needs to have good water vapor barrier, electrical insulation, mechanical strength, high and low temperature resistance, ultraviolet radiation resistance, environmental aging resistance and other properties to meet the long-term use requirements of photovoltaic solar modules.

[0003] BOPET film is a biaxially oriented polyester film with excellent comprehensive properties and can be used as the base film of photovoltaic backsheets. However, since photovoltaic backsheets are used outdoors for a long time, the existing BOPET film has weak resistance to ultraviolet radiation, which makes photovoltaic backsheets prone to failure during use. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in order to solve the problem in the prior art that BOPET film is easy to cause failure of photovoltaic backboard when used for photovoltaic backboard, the present invention provides a BOPET film for photovoltaic backboard, and the BOPET film simultaneously introduces an anti-ultraviolet functional masterbatch to improve the anti-ultraviolet performance of the BOPET film and improve its weather resistance, so that after being used for the photovoltaic backboard, the photovoltaic backboard is prevented from failing during use, the long-term use reliability of the photovoltaic backboard is improved, and the problem in the prior art that BOPET film is easy to cause failure of photovoltaic backboard when used for the photovoltaic backboard is solved.

[0005] The technical solution adopted by the present invention to solve the technical problem is:

[0006] A BOPET film for a photovoltaic back sheet, comprising a polyester core layer, and polyester surface layers co-extruded on the upper and lower surfaces of the polyester core layer;

[0007] The polyester surface layer comprises the following components in parts by weight:

[0008] 10-15 parts of open masterbatch;

[0009] 65-80 pieces of polyester chips;

[0010] 10-20 parts of anti-ultraviolet functional masterbatch;

[0011] The polyester core layer comprises the following components in parts by weight:

[0012] 5-10 parts of anti-ultraviolet functional masterbatch;

[0013] Polyester chips 90-95 parts;

[0014] The anti-ultraviolet functional masterbatch comprises the following components in parts by weight:

[0015]

[0016] Optionally, the anti-ultraviolet protective agent is selected from at least one of pyromellitic anhydride and diisocyanate.

[0017] Optionally, the anti-ultraviolet functional masterbatch is prepared according to the following method:

[0018] S01: according to the formula, the terephthalic acid, ethylene glycol, antimony trioxide, trimethyl phosphate, anti-ultraviolet protective agent and anti-ultraviolet agent are added into the reaction kettle, and the temperature is raised to 180-220° C. and the pressure reaches 0.4-0.5 MPa under an inert gas atmosphere, and the temperature is kept for 60-120 minutes;

[0019] S02: Raise the temperature in the reactor to 240-250°C and keep it warm for 100-200 minutes;

[0020] S03: reduce the pressure in the reactor to 200-250Pa, then increase the temperature in the reactor to 260-280°C, and keep it warm for 200-300min;

[0021] S04: removing small molecular impurities in the reaction system by distillation, and finally obtaining an anti-ultraviolet functional masterbatch with a viscosity of 0.700-0.750 dL / g, a melting point of 250-270° C., and an average molecular weight of 35000-40000 by melt extrusion granulation.

[0022] Optionally, the anti-UV functional masterbatch includes anti-UV functional masterbatch A and anti-UV functional masterbatch B; the mass ratio of the anti-UV functional masterbatch A to the anti-UV functional masterbatch B is 1:1; the anti-UV agent in the anti-UV functional masterbatch A is the anti-UV agent A for blocking UV-b band ultraviolet rays; the anti-UV agent in the anti-UV functional masterbatch B is the anti-UV agent B for blocking UV-a band ultraviolet rays.

[0023] Optionally, the anti-ultraviolet agent A is prepared according to the following method:

[0024] S101: Under an inert gas atmosphere, a magnesium stick and iodine are mixed, and then anhydrous tetrahydrofuran is added, the temperature is raised to no more than 60° C., a mixed solution of bromobenzene and anhydrous tetrahydrofuran is added dropwise, and heating is stopped; after the addition is completed, the mixture is heated under reflux to obtain reagent α;

[0025] S102: The reagent α is cooled to room temperature, and is added dropwise to a solution of cyanuric chloride in anhydrous tetrahydrofuran. After reacting at 0 to 20° C., toluene and an aqueous solution of hydrochloric acid are added in sequence, stirred, and quenched. The organic phase is separated and washed with pure water, concentrated, and the crude product is recrystallized with sec-butyl alcohol, filtered, washed with water, and dried to obtain a white solid intermediate α.

[0026] S103: The intermediate α and aluminum chloride are dissolved in chlorobenzene, added into a three-necked flask, maintained at 75-85° C. for 40-60 min, and then m-diphenol is added, and the mixture is reacted at 65-75° C. for 4-8 h; after the reaction is completed, the mixture is cooled to room temperature, poured into a hydrochloric acid aqueous solution, filtered, washed with water until neutral, and vacuum dried at 65-75° C. to obtain a light yellow solid intermediate β;

[0027] S104: The intermediate β, anhydrous potassium carbonate and DMF solvent are mixed, stirred and dissolved, and the temperature is raised to 70-90° C. At this temperature, n-octane chloride is added dropwise, and the mixture is reacted at a constant temperature, cooled, precipitated, and filtered to obtain the anti-ultraviolet agent A.

[0028] Optionally, the mass ratio of the magnesium bar, the iodine and the cyanuric chloride is (2.5-3.0): (0.03-0.07): (5.0-7.0).

[0029] Optionally, the mass ratio of the intermediate α to the aluminum chloride is 1:1; the mass ratio of the intermediate β to the anhydrous potassium carbonate is (3.0-4.0):(1.0-2.0).

[0030] Optionally, the anti-ultraviolet agent B is prepared according to the following method:

[0031] S201: Add concentrated hydrochloric acid to a four-necked flask filled with deionized water, add 2-nitroaniline, cool to 0-3°C with stirring, then dropwise add an aqueous solution of sodium nitrite to the four-necked flask, continue to react at 0-3°C for 1-2h after the dropwise addition is complete, add aminosulfonic acid, and filter to obtain reagent β;

[0032] S202: Add p-methylphenol, sodium hydroxide, anhydrous sodium carbonate and deionized water into a four-necked flask, stir at 0-3°C after fully dissolved, then dropwise add the reagent β, continue to react for 2-4h after the dropwise addition is complete, filter, wash with alcohol, and dry to obtain a red solid intermediate γ;

[0033] S203: The toluene solution of the intermediate γ is pumped into a tubular reactor containing an aluminum oxide catalyst through a horizontal flow pump under a hydrogen pressure of 2.0-2.5 MPa to obtain the anti-ultraviolet agent B.

[0034] Optionally, the mass ratio of the 2-nitroaniline, the sodium nitrite, the p-methylphenol, the sodium hydroxide and the anhydrous sodium carbonate is (25-30): (15-25): (20-25): (5-10): (60-65).

[0035] Another object of the present invention is to provide a method for preparing the BOPET film for photovoltaic backsheet as described above, comprising the following steps:

[0036] S1: According to the formula, the polyester surface layer material is transported to the extruder A for melt extrusion; the polyester core layer material is transported to the extruder B for melt extrusion;

[0037] S2: melt-extrude the molten polyester surface layer material and the polyester core layer material through a three-layer co-extrusion die head, and form an ABA three-layer co-extrusion structure thick sheet by a rotating cooling roller;

[0038] S3: biaxially stretching the thick sheet after preheating, longitudinally stretching it by 2.5-3.5 times and transversely stretching it by 2.5-3.5 times;

[0039] S4: The biaxially stretched thick sheet is heat-set at 230-250° C., cooled, rolled up and slit to obtain a BOPET film for a photovoltaic back sheet.

[0040] The beneficial effects of the present invention are:

[0041] The BOPET film for the photovoltaic backboard provided by the present invention is formed by ABA three-layer co-extrusion compounding, and a specific anti-ultraviolet functional masterbatch is selected for the polyester surface layer and the polyester core layer, which well solves the problems of weak anti-ultraviolet performance and poor weather resistance of the BOPET polyester film, thereby improving the long-term use reliability of the photovoltaic backboard, increasing the service life of solar cells, and further reducing the long-term use cost of photovoltaic power generation. DETAILED DESCRIPTION

[0042] The present invention is now further described in detail. The embodiments described below are exemplary and intended to be used to explain the present invention, but cannot be understood as limiting the present invention. All other embodiments obtained by ordinary technicians in this field without creative work based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0043] In order to solve the problem that the BOPET film in the prior art is easy to cause failure of the photovoltaic backsheet when used for the photovoltaic backsheet, the present invention provides a BOPET film for the photovoltaic backsheet, the film comprising a polyester core layer, and a polyester surface layer co-extruded on the upper and lower surfaces of the polyester core layer;

[0044] The polyester surface layer comprises the following components in parts by weight:

[0045] 10-15 parts of open masterbatch;

[0046] 65-80 pieces of polyester chips;

[0047] 10-20 parts of anti-ultraviolet functional masterbatch;

[0048] The polyester core layer comprises the following components in parts by weight:

[0049] 5-10 parts of anti-ultraviolet functional masterbatch;

[0050] Polyester chips 90-95 parts;

[0051] The present invention introduces anti-ultraviolet functional masterbatch into the polyester core layer and the polyester surface layer to improve the anti-ultraviolet performance of the film, thereby improving the weather resistance of the film, so that when the film is used for a photovoltaic backboard, the long-term use reliability of the photovoltaic backboard is improved and the service life of the photovoltaic backboard is extended.

[0052] Specifically, the anti-ultraviolet functional masterbatch includes the following components in parts by weight:

[0053]

[0054] The anti-ultraviolet functional masterbatch improves the anti-ultraviolet performance of the BOPET film by introducing an anti-ultraviolet agent. At the same time, an anti-ultraviolet protective agent is introduced. The anti-ultraviolet protective agent is combined with the matrix to make the anti-ultraviolet agent component less susceptible to external interference and exist in the BOPET film for a long time, thereby extending the retention time of the anti-ultraviolet agent, thereby helping to improve the durability and stability of the anti-ultraviolet performance of the BOPET film during use, and further improve the long-term weather resistance of the photovoltaic backplane.

[0055] The BOPET film for the photovoltaic backboard provided by the present invention is formed by ABA three-layer co-extrusion compounding, and a specific anti-ultraviolet functional masterbatch is selected for the polyester surface layer and the polyester core layer, which well solves the problems of weak anti-ultraviolet performance and poor weather resistance of the BOPET polyester film, thereby improving the long-term use reliability of the photovoltaic backboard, increasing the service life of solar cells, and further reducing the long-term use cost of photovoltaic power generation.

[0056] Specifically, the present invention preferably selects at least one of the anti-ultraviolet protective agent selected from pyromellitic anhydride and diisocyanate; by introducing the anti-ultraviolet protective agent to cooperate with the matrix, the damage of the PET matrix in the film due to long-term external environment is alleviated, thereby reducing the loss rate of the anti-ultraviolet components in the BOPET film and improving the durability of the anti-ultraviolet performance of the BOPET film.

[0057] Specifically, the open masterbatch in the present invention is Yihua masterbatch FG610; the polyester chips are Yizheng chips FG720A.

[0058] The preferred anti-ultraviolet functional masterbatch of the present invention is prepared according to the following method:

[0059] S01: According to the formula, add terephthalic acid, ethylene glycol, antimony trioxide, trimethyl phosphate, anti-ultraviolet protective agent and anti-ultraviolet agent into the reaction kettle, raise the temperature to 180-220℃ under inert gas atmosphere, and at the same time, the pressure reaches 0.4-0.5MPa, and keep warm for 60-120min;

[0060] S02: Raise the temperature in the reactor to 240-250°C and keep it warm for 100-200 minutes;

[0061] S03: reduce the pressure in the reactor to 200-250Pa, then increase the temperature in the reactor to 260-280°C, and keep it warm for 200-300min;

[0062] S04: removing small molecular impurities in the reaction system by distillation, and finally obtaining an anti-ultraviolet functional masterbatch with a viscosity of 0.700-0.750 dL / g, a melting point of 250-270°C, and an average molecular weight of 35000-40000 by melt extrusion granulation; the mass percentage of the anti-ultraviolet functional component in the anti-ultraviolet functional masterbatch is 8%-10%.

[0063] In the present invention, the inert gas in step S01 is preferably nitrogen.

[0064] The anti-ultraviolet agent in the present invention has a special molecular structure, in which there are intramolecular hydrogen bonds. Under normal conditions, the hydrogen bonds are closed. When irradiated with ultraviolet light of a specific wavelength, it absorbs ultraviolet light energy and reaches an excited state. The intramolecular proton transfer opens the intramolecular hydrogen bonds, and the molecule becomes an unstable keto structure and returns to the ground state. At the same time, the light energy is converted into heat energy and released, which is equivalent to the energy of absorbing ultraviolet light by itself, avoiding the interference of the macromolecular system by the ultraviolet light energy, thereby preventing the polymer material from being photo-oxidized or photo-degraded, and playing an anti-ultraviolet role.

[0065] To ensure anti-ultraviolet performance, the present invention preferably includes an anti-ultraviolet functional masterbatch A and an anti-ultraviolet functional masterbatch B; and further preferably, the mass ratio of the anti-ultraviolet functional masterbatch A to the anti-ultraviolet functional masterbatch B is 1:1; wherein the anti-ultraviolet agent in the anti-ultraviolet functional masterbatch A is an anti-ultraviolet agent A for blocking UV-b band ultraviolet rays; the anti-ultraviolet agent in the anti-ultraviolet functional masterbatch B is an anti-ultraviolet agent B for blocking UV-a band ultraviolet rays, and the other components in the two are the same.

[0066] The anti-ultraviolet agent A and the anti-ultraviolet agent B can be purchased directly; in order to ensure the anti-ultraviolet performance, the present invention preferably prepares the anti-ultraviolet agent A according to the following method:

[0067] S101: Under an inert gas atmosphere, a magnesium bar and iodine are mixed, and then anhydrous tetrahydrofuran is added, and the temperature is raised to no more than 60° C., preferably after reacting for 20-40 seconds, a mixed solution of bromobenzene and anhydrous tetrahydrofuran is added dropwise, and the heating device is removed to stop heating; after the addition is completed, the mixture is heated to reflux, preferably heated to reflux for 2 hours until the reaction is completed, to obtain reagent α;

[0068] S102: Cool the reagent α to room temperature, and add it dropwise to a solution of cyanuric chloride in anhydrous tetrahydrofuran, preferably, the mass volume ratio of cyanuric chloride to anhydrous tetrahydrofuran in the solution of cyanuric chloride is (5.0-7.0) g: (35-45) ml; react at 0-20° C., and after the addition is completed, continue to stir the reaction at room temperature until the reaction is complete, wait for 2-4 hours, add toluene and aqueous hydrochloric acid solution in sequence, preferably, the mass concentration of the aqueous hydrochloric acid solution is 12%, stir, quench, separate the organic phase, wash with pure water, concentrate, recrystallize the crude product with sec-butyl alcohol, filter, wash with water, and dry to obtain a white solid intermediate α;

[0069] S103: Dissolve the intermediate α and aluminum chloride in chlorobenzene, add to a three-necked flask, maintain at 75-85° C. for 40-60 min, then add m-diphenol, and react at 65-75° C. for 4-8 h; after the reaction is completed, cool to room temperature, pour the mixture into a hydrochloric acid aqueous solution, preferably with a mass concentration of 12%, filter, wash with water until neutral, and vacuum dry at 65-75° C. to obtain a light yellow solid intermediate β;

[0070] S104: Mix the intermediate β, anhydrous potassium carbonate and DMF solvent, stir to dissolve, and heat to 70-90°C. At this temperature, slowly drop octane chloride, and react at a constant temperature for 2-3 hours to the reaction end point. Cool, precipitate, and filter to obtain an anti-ultraviolet agent A, the main component of which is 2-(2'-hydroxy-4'octyloxyphenyl)-4,6-di(4"-methylphenyl)-1,3,5-triazine.

[0071] In the preferred embodiment of the present invention, the inert gas in step S101 is nitrogen, the magnesium strip is a polished magnesium strip, and the mass ratio of the magnesium strip, iodine and cyanuric chloride is preferably (2.5-3.0): (0.03-0.07): (5.0-7.0), and the mass volume ratio of the magnesium strip to anhydrous tetrahydrofuran in step S101 is preferably (2.5-3.0) g: (10-30) ml; the mass volume ratio of the magnesium strip in step S101 to the toluene and hydrochloric acid aqueous solution in step S102 is preferably (2. 5-3.0)g:(50-70)ml; the mass ratio of intermediate α to aluminum chloride is 1:1; preferably, in step S103, the mass volume ratio of intermediate α to aqueous hydrochloric acid solution is (2.0-3.0)g:(100-150)ml; the mass ratio of intermediate β to anhydrous potassium carbonate is (3.0-4.0)g:(1.0-2.0); in step S104, the mass volume ratio of intermediate β to DMF solvent is (3.0-4.0)g:(30-50)ml.

[0072] The anti-ultraviolet agent A can specifically absorb UV-b band ultraviolet light in the range of 280-320nm, so that the BOPET film can block UV-b band ultraviolet light. The ultraviolet absorption process is as follows:

[0073]

[0074] The anti-ultraviolet agent B in the present invention is prepared according to the following method:

[0075] S201: Add concentrated hydrochloric acid to a four-necked flask filled with deionized water, add 2-nitroaniline, cool to 0-3°C with stirring, then dropwise add an aqueous solution of sodium nitrite to the four-necked flask, preferably slowly dropwise add the aqueous solution of sodium nitrite to the four-necked flask within 0.5h, continue to react at 0-3°C for 1-2h after the dropwise addition is completed, add aminosulfonic acid, preferably add excess aminosulfonic acid, filter to obtain reagent β, and store the reagent β in a refrigerator for standby use;

[0076] S202: Add p-methylphenol, sodium hydroxide, anhydrous sodium carbonate and deionized water to a four-necked flask, stir at 0-3°C for 0.5h after fully dissolved, then dropwise add reagent β, preferably slowly add the reagent β within 1h using a constant pressure dropping funnel, continue to react for 2-4h after the dropwise addition is completed until the reaction is complete, filter, wash with alcohol, and dry to obtain a red solid intermediate γ;

[0077] S203: The toluene solution of the intermediate γ is pumped into a 100-150°C tubular reactor containing an aluminum oxide catalyst through a horizontal flow pump under a hydrogen pressure of 2.0-2.5MPa, and the flow rate of the horizontal flow pump is preferably 0.10-0.15ml / min to obtain an anti-ultraviolet agent B; in this step, the mass concentration of the intermediate γ toluene solution is preferably 5%, and a uniform intermediate γ toluene solution is preferably prepared by ultrasound; the main component of the anti-ultraviolet agent B is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole.

[0078] The preferred mass ratio of 2-nitroaniline, sodium nitrite, p-methylphenol, sodium hydroxide and anhydrous sodium carbonate in the present invention is (25-30): (15-25): (20-25): (5-10): (60-65); the preferred mass volume ratio of 2-nitroaniline to concentrated hydrochloric acid and deionized water in step S201 is (25-30) g: (70-90) ml: 100 ml; the preferred mass volume ratio of p-methylphenol to deionized water in step S202 is (25-30) g: 600 ml.

[0079] The anti-ultraviolet agent B can specifically absorb UV-a band ultraviolet light in the range of 320-400nm, so that the BOPET film can block UV-a band ultraviolet light. The ultraviolet absorption process is as follows:

[0080]

[0081] The present invention uses the anti-ultraviolet agent A and the anti-ultraviolet agent B in combination, so that the BOPET film can block ultraviolet rays of the entire wavelength range, thereby making the BOPET film have excellent anti-ultraviolet performance.

[0082] The BOPET film provided by the present invention is a weather-resistant transparent BOPET film. The anti-ultraviolet agent used, by selecting specific raw materials and a specific preparation process, has a higher ultraviolet cutoff rate and a lower yellowing index after UV aging compared with other anti-ultraviolet agents. It has stronger anti-ultraviolet ability, can effectively improve the weather resistance of photovoltaic products, and can better meet terminal needs.

[0083] Another object of the present invention is to provide a method for preparing the BOPET film for photovoltaic backsheet as described above, the method comprising the following steps:

[0084] S1: According to the formula, the polyester surface layer material is transported to the extruder A for melt extrusion; the polyester core layer material is transported to the extruder B for melt extrusion;

[0085] S2: melt-extrude the molten polyester surface layer material and the polyester core layer material through a three-layer co-extrusion die head, and form an ABA three-layer co-extrusion structure thick sheet by a rotating cooling roller;

[0086] S3: After preheating, the thick sheet is biaxially stretched to 2.5-3.5 times in the longitudinal direction and 2.5-3.5 times in the transverse direction;

[0087] S4: The biaxially stretched thick sheet is heat-set at 230-250° C., cooled, rolled up and slit to obtain a BOPET film for a photovoltaic back sheet.

[0088] The preparation method of the BOPET film for the photovoltaic backboard provided by the present invention has the advantages of simple preparation process, low operation difficulty, excellent processing performance and wider application range; the prepared BOPET film for the photovoltaic backboard is formed by ABA three-layer co-extrusion compounding, and a specific anti-ultraviolet functional masterbatch is selected for the polyester surface layer and the polyester core layer, which well solves the problems of weak anti-ultraviolet performance and poor weather resistance of the BOPET polyester film, thereby improving the long-term use reliability of the photovoltaic backboard, increasing the service life of solar cells, and further reducing the long-term use cost of photovoltaic power generation.

[0089] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below.

[0090] Unless otherwise specified, the anti-ultraviolet functional masterbatch in each embodiment of the present invention and the comparative example is prepared according to the following method:

[0091] S01: According to the formula, add terephthalic acid, ethylene glycol, antimony trioxide, trimethyl phosphate, anti-ultraviolet protective agent and anti-ultraviolet agent into the reactor, and raise the temperature of the reactor to 200°C under the protection of nitrogen atmosphere, and the pressure reaches 0.4MPa, and keep warm for 120min;

[0092] S02: Raise the temperature in the reactor to 240°C and keep it warm for 200 minutes;

[0093] S03: reduce the pressure in the reactor to 220 Pa, then raise the temperature in the reactor to 265°C and keep it warm for 280 minutes;

[0094] S04: removing small molecular impurities in the reaction system by distillation, and finally obtaining an anti-ultraviolet functional masterbatch with a viscosity of 0.730 dL / g, a melting point of 270°C, and an average molecular weight of 38,000 by melt extrusion granulation; the mass percentage of the anti-ultraviolet functional component in the anti-ultraviolet functional masterbatch is 10%.

[0095] When the anti-ultraviolet agent in step S01 is anti-ultraviolet agent A, the anti-ultraviolet functional masterbatch obtained in step S04 is anti-ultraviolet functional masterbatch A; when the anti-ultraviolet agent in step S01 is anti-ultraviolet agent B, the anti-ultraviolet functional masterbatch obtained in step S04 is anti-ultraviolet functional masterbatch B.

[0096] Wherein the anti-ultraviolet agent A is prepared according to the following method:

[0097] S101: Under nitrogen atmosphere, add 2.7 g of polished magnesium bar and 0.05 g of iodine into a four-necked flask, then add 20 ml of anhydrous tetrahydrofuran (anhydrous THF), slowly raise the temperature not exceeding 60°C, take 10% of a mixed solution of 10 ml of bromobenzene and 20 ml of anhydrous THF, add the mixed solution dropwise into the four-necked flask after 30 seconds, and remove the heating device. After the addition is complete, continue heating and reflux for 2 hours until the reaction is complete to obtain reagent α;

[0098] S102: Reagent α is cooled to room temperature, and is added dropwise to 6.2 g of cyanuric chloride in 40 ml of anhydrous THF through a constant pressure dropping funnel, and reacted at 0-20° C. After the addition is completed, the reaction is continued to be stirred at room temperature until the reaction is complete; after waiting for 3 hours, 60 ml of toluene is added to the flask, and then 60 ml of a 12% mass concentration of hydrochloric acid aqueous solution is added, stirred, quenched, the organic phase is separated and washed with pure water, concentrated, and the crude product is recrystallized with sec-butyl alcohol, filtered, washed with water, and dried to obtain a white solid intermediate α;

[0099] S103: 2.4 g of the above solid intermediate α and 2.8 g of aluminum chloride are dissolved in 40 ml of chlorobenzene, added to a three-necked flask, maintained at 80° C. for 45 min, and then 2.2 g of m-diphenol is added, and the reaction is carried out at 70° C. for 6 h. After the reaction is completed, the mixture is cooled to room temperature, and the mixture is poured into 120 ml of a 12% hydrochloric acid aqueous solution, filtered, washed with water until neutral, and vacuum dried at 70° C. to obtain a light yellow solid intermediate β;

[0100] S104: Add 3.7g of the above-mentioned solid intermediate β, 1.5g of anhydrous potassium carbonate and 40ml of DMF solvent into a three-necked flask, stir to dissolve, and heat to 80°C. At this temperature, slowly drop 1.8ml of n-octane chloride, and react at a constant temperature for 3h to the end of the reaction. Cool, precipitate, and filter to obtain the target product, anti-ultraviolet agent A, whose main component is 2-(2'-hydroxy-4'-octyloxyphenyl)-4,6-di(4'-methylphenyl)-1,3,5-triazine.

[0101] Anti-ultraviolet agent B was prepared as follows:

[0102] S201: Slowly add 75 ml of concentrated hydrochloric acid into a four-necked flask containing 100 ml of deionized water, add 27.6 g of 2-nitroaniline, and cool to 0-3°C under stirring. Then slowly dropwise add 40 ml of an aqueous solution of 20.7 g of sodium nitrite into the four-necked flask over 0.5 h. After the dropwise addition is completed, continue to react at 0-3°C for 1 h. After the reaction is completed, add excess aminosulfonic acid, filter to obtain reagent β, and store in a refrigerator for later use;

[0103] S202: Add 21.6 g of p-methylphenol, 8 g of sodium hydroxide, 63.6 g of anhydrous sodium carbonate and 600 ml of deionized water into a four-necked flask, stir for 0.5 h at 0-3 °C after fully dissolved, then slowly add the above reagent β using a constant pressure dropping funnel within 1 h, continue to react for 3 h after the addition is complete until the reaction is complete, filter, wash with alcohol, and dry to obtain a red solid intermediate γ;

[0104] S203: 5.0 g of the above-mentioned solid intermediate γ is prepared into a toluene solution reaction liquid with a mass concentration of 5% and ultrasonically homogenized. Under a hydrogen pressure of 2.5 MPa, the reaction liquid is pumped at a flow rate of 0.15 ml / min through a horizontal flow pump into a 120°C tubular reactor equipped with an aluminum oxide catalyst to obtain the target product, an anti-ultraviolet agent B, whose main component is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole.

[0105] The films in the embodiments and comparative examples of the present invention were prepared according to the following method:

[0106] S1: According to the formula, the polyester surface layer material is transported to the extruder A for melt extrusion; the polyester core layer material is transported to the extruder B for melt extrusion;

[0107] S2: melt-extrude the molten polyester surface layer material and the polyester core layer material through a three-layer co-extrusion die head, and form an ABA three-layer co-extrusion structure thick sheet by a rotating cooling roller;

[0108] S3: After preheating, the thick sheet is biaxially stretched to 2.5 times in the longitudinal direction and 2.5 times in the transverse direction;

[0109] S4: The biaxially stretched thick sheet is heat-set at 240° C., cooled, drawn, rolled and slit to obtain a BOPET film.

[0110] The thickness of the weather-resistant transparent BOPET film for photovoltaic backboard is 0.250 mm, wherein the thickness of the polyester surface layer is 0.025 mm, and the thickness of the polyester core layer is 0.225 mm.

[0111] Example 1

[0112] This embodiment provides a BOPET film for a photovoltaic backsheet, the film comprising a polyester core layer, and a polyester surface layer co-extruded on the upper and lower surfaces of the polyester core layer;

[0113] The polyester surface layer comprises the following components in parts by weight:

[0114]

[0115] The polyester core layer comprises the following components in parts by weight:

[0116] 5 parts of anti-ultraviolet functional masterbatch A;

[0117] 5 parts of anti-ultraviolet functional masterbatch B;

[0118] Polyester chips 90 pieces;

[0119] According to weight fraction, the anti-ultraviolet functional masterbatch A includes the following components:

[0120]

[0121]

[0122] According to weight fraction, the anti-ultraviolet functional masterbatch B includes the following components:

[0123]

[0124] Example 2

[0125] This embodiment provides a BOPET film for a photovoltaic backsheet, the film comprising a polyester core layer, and a polyester surface layer co-extruded on the upper and lower surfaces of the polyester core layer;

[0126] The polyester surface layer comprises the following components in parts by weight:

[0127]

[0128] The polyester core layer comprises the following components in parts by weight:

[0129] 2.5 parts of anti-ultraviolet functional masterbatch A;

[0130] 2.5 parts of anti-ultraviolet functional masterbatch B;

[0131] Polyester chips 95 parts;

[0132] According to weight fraction, the anti-ultraviolet functional masterbatch A includes the following components:

[0133]

[0134]

[0135] According to weight fraction, the anti-ultraviolet functional masterbatch B includes the following components:

[0136]

[0137] Example 3

[0138] This embodiment provides a BOPET film for a photovoltaic backsheet, the film comprising a polyester core layer, and a polyester surface layer co-extruded on the upper and lower surfaces of the polyester core layer;

[0139] The polyester surface layer comprises the following components in parts by weight:

[0140]

[0141] The polyester core layer comprises the following components in parts by weight:

[0142] 3.5 parts of anti-ultraviolet functional masterbatch A;

[0143] 3.5 parts of anti-ultraviolet functional masterbatch B;

[0144] Polyester chips 93 pieces;

[0145] According to weight fraction, the anti-ultraviolet functional masterbatch A includes the following components:

[0146]

[0147] According to weight fraction, the anti-ultraviolet functional masterbatch B includes the following components:

[0148]

[0149] Example 4

[0150] This embodiment provides a BOPET film for a photovoltaic backsheet, the film comprising a polyester core layer, and a polyester surface layer co-extruded on the upper and lower surfaces of the polyester core layer;

[0151] The polyester surface layer comprises the following components in parts by weight:

[0152]

[0153] The polyester core layer comprises the following components in parts by weight:

[0154] 5 parts of anti-ultraviolet functional masterbatch A;

[0155] 5 parts of anti-ultraviolet functional masterbatch B;

[0156] Polyester chips 90 pieces;

[0157] According to weight fraction, the anti-ultraviolet functional masterbatch A includes the following components:

[0158]

[0159] According to weight fraction, the anti-ultraviolet functional masterbatch B includes the following components:

[0160]

[0161] Example 5

[0162] This embodiment provides a BOPET film for a photovoltaic backsheet, the film comprising a polyester core layer, and a polyester surface layer co-extruded on the upper and lower surfaces of the polyester core layer;

[0163] The polyester surface layer comprises the following components in parts by weight:

[0164]

[0165]

[0166] The polyester core layer comprises the following components in parts by weight:

[0167] 5 parts of anti-ultraviolet functional masterbatch A;

[0168] 5 parts of anti-ultraviolet functional masterbatch B;

[0169] Polyester chips 90 pieces;

[0170] According to weight fraction, the anti-ultraviolet functional masterbatch A includes the following components:

[0171]

[0172] According to weight fraction, the anti-ultraviolet functional masterbatch B includes the following components:

[0173]

[0174] Example 6

[0175] This embodiment provides a BOPET film for a photovoltaic backsheet, the film comprising a polyester core layer, and a polyester surface layer co-extruded on the upper and lower surfaces of the polyester core layer;

[0176] The polyester surface layer comprises the following components in parts by weight:

[0177]

[0178] The polyester core layer comprises the following components in parts by weight:

[0179] 5 parts of anti-ultraviolet functional masterbatch A;

[0180] 5 parts of anti-ultraviolet functional masterbatch B;

[0181] Polyester chips 90 pieces;

[0182] According to weight fraction, the anti-ultraviolet functional masterbatch A includes the following components:

[0183]

[0184] According to weight fraction, the anti-ultraviolet functional masterbatch B includes the following components:

[0185]

[0186]

[0187] Comparative Example 1

[0188] The difference between this comparative example and Example 1 is that pyromellitic anhydride is not added to the anti-ultraviolet functional masterbatch A and the anti-ultraviolet functional masterbatch B.

[0189] Comparative Example 2

[0190] This comparative example provides a BOPET film, which includes a polyester core layer, and a polyester surface layer co-extruded on the upper and lower surfaces of the polyester core layer;

[0191] The polyester surface layer comprises the following components in parts by weight:

[0192] 15 parts of open masterbatch;

[0193] Polyester chips 65 pieces;

[0194] 20 parts of anti-ultraviolet functional masterbatch A;

[0195] The polyester core layer comprises the following components in parts by weight:

[0196] Anti-ultraviolet functional masterbatch A 10 parts;

[0197] Polyester chips 90 pieces;

[0198] According to weight fraction, the anti-ultraviolet functional masterbatch A includes the following components:

[0199]

[0200] Comparative Example 3

[0201] This comparative example provides a BOPET film, which includes a polyester core layer, and a polyester surface layer co-extruded on the upper and lower surfaces of the polyester core layer;

[0202] The polyester surface layer comprises the following components in parts by weight:

[0203] 15 parts of open masterbatch;

[0204] Polyester chips 65 pieces;

[0205] 20 parts of anti-ultraviolet functional masterbatch B;

[0206] The polyester core layer comprises the following components in parts by weight:

[0207] Anti-ultraviolet functional masterbatch B 10 parts;

[0208] Polyester chips 90 pieces;

[0209] According to weight fraction, the anti-ultraviolet functional masterbatch B includes the following components:

[0210]

[0211] Comparative Example 4

[0212] This comparative example provides a BOPET film, which includes a polyester core layer, and a polyester surface layer co-extruded on the upper and lower surfaces of the polyester core layer;

[0213] The polyester surface layer comprises the following components in parts by weight:

[0214]

[0215] The polyester core layer comprises the following components in parts by weight:

[0216] 5 parts of anti-ultraviolet functional masterbatch A;

[0217] 5 parts of anti-ultraviolet functional masterbatch B;

[0218] Polyester chips 90 pieces;

[0219] According to weight fraction, the anti-ultraviolet functional masterbatch A includes the following components:

[0220]

[0221] According to weight fraction, the anti-ultraviolet functional masterbatch B includes the following components:

[0222]

[0223] The commercially available anti-ultraviolet agent A in this embodiment is Taiwan Qiti HP-1064; the commercially available anti-ultraviolet agent B is Taiwan Qiti 9735A.

[0224] Comparative Example 5

[0225] This comparative example provides a BOPET film, which includes a polyester core layer, and a polyester surface layer co-extruded on the upper and lower surfaces of the polyester core layer;

[0226] The polyester surface layer comprises the following components in parts by weight:

[0227]

[0228] The polyester core layer comprises the following components in parts by weight:

[0229] 5 parts of anti-ultraviolet functional masterbatch A;

[0230] 5 parts of anti-ultraviolet functional masterbatch B;

[0231] Polyester chips 90 pieces;

[0232] According to weight fraction, the anti-ultraviolet functional masterbatch A includes the following components:

[0233] According to weight fraction, the anti-ultraviolet functional masterbatch B includes the following components:

[0234] Comparative Example 6

[0235] This comparative example provides a BOPET film, which includes a polyester core layer, and a polyester surface layer co-extruded on the upper and lower surfaces of the polyester core layer;

[0236] The polyester surface layer comprises the following components in parts by weight:

[0237]

[0238] The polyester core layer comprises the following components in parts by weight:

[0239] 5 parts of anti-ultraviolet functional masterbatch A;

[0240] 5 parts of anti-ultraviolet functional masterbatch B;

[0241] Polyester chips 90 pieces;

[0242] According to weight fraction, the anti-ultraviolet functional masterbatch A includes the following components:

[0243]

[0244] According to weight fraction, the anti-ultraviolet functional masterbatch B includes the following components:

[0245]

[0246]

[0247] The performance of the films prepared in each embodiment and comparative example was tested, and the testing method was as follows:

[0248] Weathering performance evaluation includes two parts: UV cutoff rate and yellowing index after UV aging. The UV cutoff rate test is conducted using a UV spectrophotometer with a test range of 280-400nm. The yellowing index test after UV aging is measured using the IEC 61215 measurement method and the test conditions are 60kwh / m 2、120kwh / m 2 、300kwh / m 2 , which can simulate the situations under shorter environment time, medium environment time and longer environment time respectively.

[0249] The test results are shown in Table 1.

[0250] Table 1

[0251]

[0252] It can be seen from the above data that the BOPET films prepared in various embodiments of the present invention have good weather resistance and good durability of weather resistance.

[0253] The difference between Comparative Example 1 and Example 1 is that no anti-ultraviolet protective agent is added to the anti-ultraviolet functional masterbatch, and the yellowing index of the prepared film after UV aging is relatively high, especially after 120kwh / m 2 Under the above test conditions, the yellowing index increases significantly, which means that the film's weather resistance is poor.

[0254] The difference between Comparative Example 2 and Example 1 is that only anti-ultraviolet functional masterbatch A is added to both the polyester surface layer and the polyester core layer, and the prepared film only protects against UV-b band ultraviolet light, and the weather resistance of the film is poor under the full-band ultraviolet light test;

[0255] The difference between Comparative Example 3 and Example 1 is that only the anti-ultraviolet functional masterbatch B is added to the polyester surface layer and the polyester core layer, and the prepared film only protects against UV-a band ultraviolet light, and the weather resistance of the film is poor under the full-band ultraviolet light test;

[0256] The difference between Comparative Example 4 and Example 1 is that the commercially available anti-ultraviolet agent is used instead of the self-made anti-ultraviolet agent of the present invention, and the UV cutoff rate and yellowing index of the prepared film are poor, which proves that the self-made anti-ultraviolet agent has a better effect;

[0257] The difference between Comparative Example 5 and Example 1 is that the amount of anti-ultraviolet protective agent added is reduced, and the yellowing index of the prepared film increases significantly after UV aging, that is, the durability of the film's weather resistance is poor, proving that the addition of an anti-ultraviolet protective agent can effectively improve the durability of the film's weather resistance;

[0258] The difference between Comparative Example 6 and Example 1 is that the amount of anti-ultraviolet protective agent added is increased, and the film cannot be formed normally, and the preparation process is abnormal, which indicates that adding too much anti-ultraviolet protective agent has a greater impact on the process.

[0259] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A BOPET film for photovoltaic backsheet, characterized in that: It comprises a polyester core layer, and polyester surface layers co-extruded on the upper and lower surfaces of the polyester core layer; The polyester surface layer comprises the following components in parts by weight: 10-15 parts of open masterbatch; 65-80 pieces of polyester chips; 10-20 parts of anti-ultraviolet functional masterbatch; The polyester core layer comprises the following components in parts by weight: 5-10 parts of anti-ultraviolet functional masterbatch; Polyester chips 90-95 parts; The anti-ultraviolet functional masterbatch comprises the following components in parts by weight: 1020 parts of terephthalic acid; 560 parts of ethylene glycol; 1.0 part of antimony trioxide; Trimethyl phosphate 0.8 part; 20 parts of anti-ultraviolet protective agent; 140-180 parts of anti-ultraviolet agent; The anti-ultraviolet protective agent is selected from at least one of pyromellitic anhydride and diisocyanate; The anti-ultraviolet functional masterbatch is prepared according to the following method: S01: according to the formula, the terephthalic acid, ethylene glycol, antimony trioxide, trimethyl phosphate, anti-ultraviolet protective agent and anti-ultraviolet agent are added into the reaction kettle, and the temperature is raised to 180-220° C. and the pressure reaches 0.4-0.5 MPa under an inert gas atmosphere, and the temperature is kept for 60-120 minutes; S02: Raise the temperature in the reactor to 240-250°C and keep it warm for 100-200 minutes; S03: reduce the pressure in the reactor to 200-250Pa, then increase the temperature in the reactor to 260-280°C, and keep it warm for 200-300min; S04: removing small molecular impurities in the reaction system by distillation, and finally obtaining an anti-ultraviolet functional masterbatch with a viscosity of 0.700-0.750 dL / g, a melting point of 250-270° C., and an average molecular weight of 35000-40000 by melt extrusion granulation; The anti-ultraviolet functional masterbatch includes an anti-ultraviolet functional masterbatch A and an anti-ultraviolet functional masterbatch B; the mass ratio of the anti-ultraviolet functional masterbatch A to the anti-ultraviolet functional masterbatch B is 1:1; the anti-ultraviolet agent in the anti-ultraviolet functional masterbatch A is an anti-ultraviolet agent A for blocking UV-b band ultraviolet rays; the anti-ultraviolet agent in the anti-ultraviolet functional masterbatch B is an anti-ultraviolet agent B for blocking UV-a band ultraviolet rays; The anti-ultraviolet agent A is prepared as follows: S101: Under an inert gas atmosphere, a magnesium stick and iodine are mixed, and then anhydrous tetrahydrofuran is added, the temperature is raised to no more than 60° C., a mixed solution of bromobenzene and anhydrous tetrahydrofuran is added dropwise, and heating is stopped; after the addition is completed, the mixture is heated under reflux to obtain reagent α; S102: The reagent α is cooled to room temperature, and is added dropwise to a solution of cyanuric chloride in anhydrous tetrahydrofuran. After reacting at 0-20° C., toluene and aqueous hydrochloric acid are added in sequence, stirred, and quenched. The organic phase is separated and washed with pure water, and then concentrated and the crude product is recrystallized with sec-butyl alcohol, filtered, washed with water, and dried to obtain a white solid intermediate α. S103: The intermediate α and aluminum chloride are dissolved in chlorobenzene, added into a three-necked flask, maintained at 75-85° C. for 40-60 min, and then m-diphenol is added, and the mixture is reacted at 65-75° C. for 4-8 h; after the reaction is completed, the mixture is cooled to room temperature, poured into a hydrochloric acid aqueous solution, filtered, washed with water until neutral, and vacuum dried at 65-75° C. to obtain a light yellow solid intermediate β; S104: mixing the intermediate β, anhydrous potassium carbonate and DMF solvent, stirring and dissolving, and heating to 70-90° C., adding n-octane chloride dropwise at this temperature, reacting at a constant temperature, cooling, precipitating, and filtering to obtain the anti-ultraviolet agent A; The anti-ultraviolet agent B is prepared as follows: S201: Add concentrated hydrochloric acid to a four-necked flask filled with deionized water, add 2-nitroaniline, cool to 0-3°C with stirring, then dropwise add an aqueous solution of sodium nitrite into the four-necked flask, continue to react at 0-3°C for 1-2h after the dropwise addition is complete, add aminosulfonic acid, and filter to obtain reagent β; S202: Add p-methylphenol, sodium hydroxide, anhydrous sodium carbonate and deionized water into a four-necked flask, stir at 0-3°C after fully dissolved, then dropwise add the reagent β, continue to react for 2-4h after the dropwise addition is complete, filter, wash with alcohol, and dry to obtain a red solid intermediate γ; S203: The toluene solution of the intermediate γ is pumped into a tubular reactor containing an aluminum oxide catalyst through a horizontal flow pump under a hydrogen pressure of 2.0-2.5 MPa to obtain the anti-ultraviolet agent B.

2. The BOPET film for photovoltaic backsheet according to claim 1, characterized in that: The mass ratio of the magnesium bar, the iodine and the cyanuric chloride is (2.5-3.0): (0.03-0.07): (5.0-7.0).

3. The BOPET film for photovoltaic backsheet according to claim 1, characterized in that: The mass ratio of the intermediate α to the aluminum chloride is 1:1; the mass ratio of the intermediate β to the anhydrous potassium carbonate is (3.0-4.0): (1.0-2.0).

4. The BOPET film for photovoltaic backsheet according to claim 1, characterized in that: The mass ratio of the 2-nitroaniline, the sodium nitrite, the p-methylphenol, the sodium hydroxide and the anhydrous sodium carbonate is (25-30): (15-25): (20-25): (5-10): (60-65).

5. A method for preparing a BOPET film for a photovoltaic back sheet according to any one of claims 1 to 4, characterized in that: The steps include: S1: According to the formula, the polyester surface layer material is transported to the extruder A for melt extrusion; the polyester core layer material is transported to the extruder B for melt extrusion; S2: melt-extrude the molten polyester surface layer material and the polyester core layer material through a three-layer co-extrusion die head, and form an ABA three-layer co-extrusion structure thick sheet by a rotating cooling roller; S3: biaxially stretching the thick sheet after preheating, longitudinally stretching it by 2.5-3.5 times and transversely stretching it by 2.5-3.5 times; S4: The biaxially stretched thick sheet is heat-set at 230-250° C., cooled, rolled up and slit to obtain a BOPET film for a photovoltaic back sheet.

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