A lightweight front panel film for photovoltaic applications and its preparation method

Abstract

The present invention relates to the technical field of protective films for photovoltaic materials, in particular to a lightweight front photovoltaic panel film and a preparation method thereof. The film is successively composed of a strengthening layer, an anti-aging layer A, and an anti-aging layer B, and the thickness ratio of the strengthening layer, the anti-aging layer A, and the anti-aging layer B is 1-2:1-3:1-4. The refined fibers used in the present invention have high single-ity and good dispersibility, and are easily cross-matched with the refined fibers of abaca, so that the formed film network structure has good ion filling, improving the film denseness; by modifying lanthanum chloride cellulose and subsequently adding phosphoric acid to precipitate the remaining lanthanum ions, the fibers and lanthanum ions are evenly distributed in the film body, filling the voids in the film body and improving the film strength and water vapor shielding effect.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic material protective films, in particular to a lightweight front panel film for photovoltaic and its preparation method. Background Art

[0002] In the past decade, the photovoltaic industry in China has developed rapidly. With the rapid expansion of the production capacity of photovoltaic cells, it has greatly promoted the development and upgrading of supporting materials in the industrial chain. As the main supporting material for the front panel of solar cells, polyester film has become a new growth point in the application field of polyester film.

[0003] At present, most solar module products use glass as the front panel material (typical thickness is 3.2 mm), and the weight of the glass accounts for more than 60% of the weight of the entire module, resulting in the weight of the entire module product being greater than 10 Kg / m 2 . In some occasions with low load-bearing capacity, such as the roofs of old and industrial factories, the tops of buses, etc., it is necessary to reinforce before installing solar module products. On the one hand, reinforcing the solar module products will increase additional costs and extend the recycling period of solar products; on the other hand, it is difficult to reinforce in some occasions, which requires the photovoltaic front panel material to have a certain flexibility to adapt to the combined use of both. The development of transparent polyester materials with lightweight, excellent bendability, UV resistance, and high impact resistance can greatly expand the application field of solar photovoltaic front panel materials. Therefore, it has become a trend in BIPV to use polymer materials to replace glass materials.

[0004] In the prior art, there are many similar studies. For example, a light conversion adhesive film containing a composite light conversion agent, its preparation method and a photovoltaic module with the application number CN202310693180.5, including a film main body and a composite light conversion agent dispersed in the film main body; in the light conversion adhesive film, the mass fraction of the composite light conversion agent is 0.05% - 0.5%; the composite light conversion agent is mainly prepared from the following raw materials by weight: 100 parts of benzotriazole-based light conversion powder, 1 - 10 parts of benzotriazole-based ultraviolet absorber, 0.1 - 5 parts of alkoxysilane, 0.1 - 5 parts of silicate ester, 0.1 - 1 part of hydrolysis solution, and 5 - 20 parts of solvent. Another example is a flexible photovoltaic module with adjustable color, its preparation method, a solar cell and its application with the application number CN202310693168.4, including a battery cell, a light-receiving surface transparent adhesive film layer and a front plate sequentially arranged on one side of the light-receiving surface of the battery cell, a back surface transparent adhesive film layer and a back plate sequentially arranged on the back surface of the battery cell, further including a first transparent thin film layer and a second transparent thin film layer. The first transparent thin film layer is arranged on the light-receiving surface of the battery cell and is located between the light-receiving surface of the battery cell and the light-receiving surface transparent adhesive film layer. The density of one end of the first transparent thin film layer close to the light-receiving surface of the battery cell is less than that of the other end of the first transparent thin film layer, and the density difference between the two ends is 0.2 - 1.8 g / cm<supgt;3< / supgt;, and the average refractive index of the first transparent thin film layer is 1.8 - 2.2. It can be seen that in the research in this field, the design of the film structure is mainly aimed at the density and consistency of the film, lacking the idea of strengthening the film structure with the interlacing support of fibers, resulting in the inability to further expand the overall adaptability of the film. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a lightweight photovoltaic front plate film and its preparation method. By specifically selecting refined fibers, the purpose of constructing a crisscross fiber structure in the film is achieved, so that the overall strength and practicality of the film are improved. The specific technical solutions are as follows:

[0006] A lightweight photovoltaic front plate film, which is sequentially composed of a reinforcement layer, an anti-aging layer A, and an anti-aging layer B, and the thickness ratio of the reinforcement layer, the anti-aging layer A, and the anti-aging layer B is 1 - 2:1 - 3:1 - 4.

[0007] A preparation method of a lightweight photovoltaic front plate film, including:

[0008] Ⅰ Preparation of the reinforcement layer:

[0009] (1) Preparation of refined cellulose

[0010] Mix the cyan flax and abaca, crush them into slurry, grind for 20 - 30 min at 40 - 43 °C, add 50 - 60 °C clear water 5 - 8 times the mass of the slurry, soak for 20 - 30 min, raise the temperature to the boiling point, boil for 10 - 15 min, wait for the temperature to drop to 70 - 75 °C, keep warm for 2 - 3 h, filter to obtain the filter residue for standby;

[0011] Mix the above filter residue and ethanol according to a mass ratio of 1:10 - 13, heat to 44 - 47 °C, add propanol to the mixed system and stir for 20 - 30 min; lower the temperature to 25 - 28 °C, add chloroform, seal and shake for 40 - 50 min, filter, and keep the filter residue for standby;

[0012] Mix the above filter residue and lye according to a mass ratio of 1:15 - 18 of lye, heat to boiling with microwave, keep warm for 50 - 80 min, lower the temperature to room temperature, put it into the freezer and freeze for 20 - 30 h; take it out, heat to 80 - 85 °C with microwave and keep warm for 70 - 88 min, filter, and wash the filter residue with clear water 3 - 5 times and dry for standby;

[0013] Mix the above filter residue and hydrochloric acid according to a mass ratio of 1:12 - 14, stir for 20 - 30 min, add phosphoric acid and stir for 2 - 3 h, dilute the solution 3 - 5 times, continue to stir for 3 - 5 h, and then wash with distilled water 2 - 3 times and concentrate and dry under reduced pressure;

[0014] The concentration of the hydrochloric acid is 1.5 - 1.9 mol / L; the concentration of the phosphoric acid is 1 - 1.2 mol / L; the dosage of the phosphoric acid is 8 - 10% of the hydrochloric acid;

[0015] (2) Cellulose modification

[0016] Mix the refined cellulose in the previous step and water according to a mass ratio of 1:6 - 8, introduce ozone, let it stand for 30 - 40 min, raise the temperature to 43 - 45 °C, and add potassium sulfate to obtain solution A;

[0017] Mix acrylamide and ethanol according to a mass ratio of 1:15 - 20 to obtain solution B;

[0018] Mix N,N'-methylenebisacrylamide and water according to a mass ratio of 1:25 - 30 to obtain solution C;

[0019] Add 1 - 2 parts of solution C to 10 parts of solution A, mix evenly, under ultrasonic oscillation, drop 15 - 20 parts of solution B into the aforementioned solution, and the obtained reactant is rinsed with ethanol and dried, and soaked in the calcium and magnesium solution mixture for 20 - 30 min, and then filtered and superfine pulverized to obtain calcium and magnesium hybrid cellulose;

[0020] (3) Preparation of the membrane body

[0021] Mix 50 - 60 parts of ethylene - octene copolymer resin, 60 - 70 parts of polyethylene resin, 1 - 4 parts of vinyltrimethoxysilane, 1 - 2 parts of ditert - butyl peroxide diisopropylbenzene, and 5 - 8 parts of the calcium - magnesium hybrid cellulose obtained in the previous step, melt them uniformly, and cast a film by casting.

[0022] Ⅱ Preparation of anti - aging layer A

[0023] Prepare refined cellulose according to the steps of the strengthening layer (1). Mix 10 - 13 parts of refined cellulose and 120 - 150 parts of deionized water, heat to 50 - 60 °C, add 1 - 2 parts of 1 - aminooctadecane, mix evenly, soak for 20 - 30 min, stir for 30 - 50 min, raise the temperature to 63 - 65 °C, soak for 3 - 5 h, and filter.

[0024] Mix the filter residue with the citric acid solution in a mass ratio of 1:15, stir at 58 - 66 °C for 50 - 70 min, add the lanthanum chloride solution, stir for 2 - 3 h, drop the phosphoric acid solution into the solution, and let it stand for 50 - 60 min; filter; wash the filter residue with distilled water 3 - 5 times, dry it, and ultrafinely crush the dried modified cellulose to obtain rare - earth hybrid cellulose.

[0025] Mix 55 - 65 parts of ethylene - octene copolymer resin, 68 - 72 parts of polyethylene resin, 1 - 4 parts of vinyltrimethoxysilane, 1 - 2 parts of ditert - butyl peroxide diisopropylbenzene, and 6 - 9 parts of rare - earth hybrid cellulose, melt them uniformly, and cast a film by casting to obtain anti - aging layer A.

[0026] The mass concentration of the citric acid solution is 0.8 - 1.3 g / L; the mass concentration of the lanthanum chloride solution is 0.1 - 0.3%; the dosage of the lanthanum chloride solution is 2 - 3 times the mass of the filter residue; the concentration of the phosphoric acid solution is 0.1 - 0.3%, and the dosage is 1 - 1.3 times the mass of the cellulose.

[0027] Ⅲ Preparation of anti - aging layer B

[0028] Mix the aforementioned calcium - magnesium hybrid cellulose and rare - earth hybrid cellulose in a mass ratio of 6:1 - 1.4, add it to the film body in an amount of 3 - 6%, and perform subsequent operations according to the film preparation steps of the strengthening layer; press, cool, and wind up each layer to form a lightweight photovoltaic front - panel film.

[0029] Further, the mass ratio of flax to abaca is 1 - 2:2 - 4.

[0030] Further, the dosage of propanol is 1 / 5 - 1 / 4 of that of ethanol.

[0031] Further, the dosage of chloroform is 1 / 4 - 1 / 3 of that of ethanol.

[0032] Further, the lye is a sodium hydroxide solution with a mass fraction of 5.6 - 7.9%.

[0033] Further, the microwave power is 800 - 900 W.

[0034] Further, the temperature of the freezer is -20 - 30 °C.

[0035] Further, the concentration of ozone in the solution is 1.8 - 2.3 mg / L.

[0036] Further, the dosage of potassium sulfate is 6 - 8% of the mass of the refined cellulose; the calcium - magnesium solution is composed of calcium chloride, magnesium chloride, and water mixed in a mass ratio of 10:1 - 2:200 - 300.

[0037] Compared with the prior art, the technical effects of the present invention are as follows:

[0038] Through targeted fiber selection, using the characteristics of flax bundle fibers, the extracted refined fibers have high single - ness and good dispersibility, and are easy to form cross - matching with the refined fibers of abaca. During alkalization treatment, freezing causes the molecules to break under the action of ice crystals, reducing the agglomeration probability during fiber use. Then, after the fibers are modified, the molecular structure is extended to strengthen the spatial combination structure of the fibers; through the adsorption of calcium and magnesium ions in the calcium - magnesium solution, the formed membrane network structure has good ion filling, improving the membrane denseness; by modifying lanthanum chloride cellulose, the subsequent addition of phosphoric acid precipitates the remaining lanthanum ions, making the fibers and lanthanum ions evenly distributed in the membrane body, filling the voids in the membrane body, and improving the membrane strength and water vapor shielding effect. Specific Embodiments

[0039] The following combines specific embodiments to further limit the technical solutions of the present invention, but the scope of protection required is not limited to the description made.

[0040] Example 1

[0041] A lightweight front panel film for photovoltaic applications, which is successively composed of a strengthening layer, an anti - aging layer A, and an anti - aging layer B, and the thickness ratio of the strengthening layer, anti - aging layer A, and anti - aging layer B is 1:1:1;

[0042] The preparation method of the lightweight front panel film for photovoltaic applications in this example is as follows:

[0043] Ⅰ Preparation of the strengthening layer

[0044] (1) Preparation of refined cellulose

[0045] Mix the green flax and abaca, crush them into a slurry, grind for 20 min at 40 °C, add 5 times the mass of the slurry of clear water, soak at 50 °C for 20 min, raise the temperature to the boiling point, boil for 10 min, wait for the temperature to drop to 70 °C, keep warm for 2 h, filter to obtain the filter residue for standby;

[0046] Mix the above-mentioned filter residue and ethanol in a mass ratio of 1:10, heat to 44 °C, add propanol to the mixing system and stir for 20 min; lower the temperature to 25 °C, add chloroform, seal and shake for 40 min, filter, and reserve the filter residue;

[0047] The mass ratio of the flax to the abaca is 1:2; the dosage of the propanol is 1 / 5 of that of the ethanol; the dosage of the chloroform is 1 / 4 of that of the ethanol;

[0048] Mix the above-mentioned filter residue and lye in a mass ratio of 1:15, heat to boiling with microwave, keep warm for 50 min, lower the temperature to room temperature, put it into a freezer and freeze for 20 h; take it out, heat to 80 °C with microwave and keep warm for 70 min, filter, and wash the filter residue 3 times with clear water and dry for standby;

[0049] The lye is a sodium hydroxide solution with a mass fraction of 5.6%; the microwave power is 800 W; the temperature of the freezer is -20 °C;

[0050] Mix the above-mentioned filter residue and hydrochloric acid in a mass ratio of 1:12, stir for 20 min, add phosphoric acid and stir for 2 h, dilute the solution by 3 times, continue to stir for 3 h, and then wash 2 times with distilled water and concentrate under reduced pressure and dry;

[0051] The concentration of the hydrochloric acid is 1.5 mol / L; the concentration of the phosphoric acid is 1 mol / L; the dosage of the phosphoric acid is 8% of that of the hydrochloric acid;

[0052] (2) Cellulose modification

[0053] Mix the refined cellulose in the previous step and water in a mass ratio of 1:6, introduce ozone, let it stand for 30 min, raise the temperature to 43 °C, and add potassium sulfate to obtain solution A;

[0054] Mix acrylamide and ethanol in a mass ratio of 1:15 to obtain solution B;

[0055] Mix N,N'-methylenebisacrylamide and water in a mass ratio of 1:25 to obtain solution C;

[0056] Add 1 part of solution C to 10 parts of solution A, mix evenly, under ultrasonic oscillation, drop 15 parts of solution B into the aforementioned solution, wash and dry the obtained reactant with ethanol, soak in a calcium and magnesium solution for 20 min, filter and ultrafinely pulverize to obtain calcium and magnesium hybrid cellulose;

[0057] The concentration of ozone in the solution is 1.8 mg / L; the dosage of potassium sulfate is 6% of the mass of the refined cellulose; the calcium-magnesium solution is prepared by mixing calcium chloride, magnesium chloride and water in a mass ratio of 10:1:200;

[0058] (3) Preparation of the film body

[0059] Mix 50 parts of ethylene-octene copolymer resin, 60 parts of polyethylene resin, 1 part of vinyltrimethoxysilane, 1 part of ditert-butylperoxide diisopropylbenzene, and 5 parts of the calcium-magnesium hybrid cellulose prepared in the previous step and melt them, then cast and form a film;

[0060] II Preparation of the anti-aging layer A

[0061] Prepare refined cellulose according to the steps of the strengthening layer (1). Mix 10 parts of refined cellulose and 120 parts of deionized water, heat to 50 °C, add 1 part of 1-aminooctadecane, mix evenly, soak for 20 min, stir for 30 min, raise the temperature to 63 °C, soak for 3 h, and filter;

[0062] Mix the filter residue with the citric acid solution in a mass ratio of 1:15, stir at 58 °C for 50 min, add the lanthanum chloride solution, stir for 2 h, drop the phosphoric acid solution into the solution and let it stand for 50 min; filter; wash the filter residue with distilled water 3 times, dry it, and ultrafinely crush the dried modified cellulose to obtain rare-earth hybrid cellulose;

[0063] Mix 55 parts of ethylene-octene copolymer resin, 68 parts of polyethylene resin, 1 part of vinyltrimethoxysilane, 1 part of ditert-butylperoxide diisopropylbenzene, and 6 parts of rare-earth hybrid cellulose and melt them, then cast and form a film to obtain the anti-aging layer A;

[0064] The mass concentration of the citric acid solution is 0.8 g / L; the mass concentration of the lanthanum chloride solution is 0.1%; the dosage of the lanthanum chloride solution is 2 times the mass of the filter residue; the concentration of the phosphoric acid solution is 0.1%, and the dosage is 1 time the mass of the cellulose;

[0065] III Preparation of the anti-aging layer B

[0066] Mix the aforementioned calcium-magnesium hybrid cellulose and rare-earth hybrid cellulose in a mass ratio of 6:1, add it to the film body in a dosage of 3%, and perform subsequent operations according to the film body preparation steps of the strengthening layer; press, cool, and wind up each layer to form a lightweight photovoltaic front panel film.

[0067] Example 2

[0068] A lightweight photovoltaic front panel film, which is successively composed of a strengthening layer, an anti-aging layer A, and an anti-aging layer B. The thickness ratio of the strengthening layer, the anti-aging layer A, and the anti-aging layer B is 2:3:4;

[0069] The preparation method of the lightweight photovoltaic front panel film in this embodiment is as follows:

[0070] Ⅰ. Prepare the strengthening layer

[0071] (1) Prepare refined cellulose

[0072] Mix the green flax and abaca, crush them into slurry, grind for 30 min at 43 °C, add 8 times the mass of the slurry of clear water, soak at 60 °C for 30 min, raise the temperature to the boiling point, boil for 15 min, wait for the temperature to drop to 75 °C, keep warm for 3 h, filter to obtain the filter residue for standby;

[0073] Mix the above filter residue with ethanol according to a mass ratio of 1:13, heat to 47 °C, add propanol to the mixed system and stir for 30 min; lower the temperature to 28 °C, add chloroform, seal and shake for 50 min, filter, and keep the filter residue for standby;

[0074] The mass ratio of the flax to the abaca is 1:4; the dosage of the propanol is 1 / 4 of that of the ethanol; the dosage of the chloroform is 1 / 3 of that of the ethanol;

[0075] Mix the above filter residue with the lye according to a mass ratio of 1:18 of the lye, heat to boiling with microwave, keep warm for 80 min, lower the temperature to room temperature, put it into a freezer and freeze for 30 h; take it out, heat to 85 °C with microwave and keep warm for 88 min, filter, and wash the filter residue 5 times with clear water and dry for standby;

[0076] The lye is a sodium hydroxide solution with a mass fraction of 5.6 - 7.9%; the microwave power is 800 - 900 W; the temperature of the freezer is -20 - 30 °C;

[0077] Mix the above filter residue with hydrochloric acid according to a mass ratio of 1:14, stir for 30 min, add phosphoric acid and stir for 3 h, dilute the solution 5 times, continue to stir for 5 h, and then wash 3 times with distilled water and concentrate under reduced pressure and dry;

[0078] The concentration of the hydrochloric acid is 1.9 mol / L; the concentration of the phosphoric acid is 1.2 mol / L; the dosage of the phosphoric acid is 10% of that of the hydrochloric acid;

[0079] (2) Modify cellulose

[0080] Mix the refined cellulose in the previous step with water according to a mass ratio of 1:8, introduce ozone, let it stand for 40 min, raise the temperature to 45 °C, and add potassium sulfate to obtain solution A;

[0081] Mix acrylamide with ethanol according to a mass ratio of 1:20 to obtain solution B;

[0082] Mix N,N'-methylenebisacrylamide with water according to a mass ratio of 1:30 to obtain solution C;

[0083] Add 2 parts of solution C to 10 parts of solution A, mix evenly, and while under ultrasonic oscillation, drip 20 parts of solution B into the aforementioned solution. The resulting reactant is rinsed with ethanol and dried, soaked in a calcium and magnesium solution mixture for 30 min, and then filtered and superfine pulverized to obtain calcium and magnesium hybrid cellulose;

[0084] The concentration of ozone in the solution is 2.3 mg / L; the dosage of potassium sulfate is 8% of the mass of the refined cellulose; the calcium and magnesium solution is prepared by mixing calcium chloride, magnesium chloride, and water in a mass ratio of 10:2:299;

[0085] (3) Prepare the film body

[0086] Mix 60 parts of ethylene-octene copolymer resin, 70 parts of polyethylene resin, 4 parts of vinyltrimethoxysilane, 2 parts of diisopropylbenzene peroxide, and 8 parts of the calcium and magnesium hybrid cellulose prepared in the previous step, melt and mix them evenly, and then cast and form a film;

[0087] Ⅱ Prepare the anti-aging layer A

[0088] Prepare refined cellulose according to the steps of the strengthening layer (1). Mix 13 parts of refined cellulose and 150 parts of deionized water, heat to 60 °C, add 2 parts of 1-aminooctadecane, mix evenly, soak for 30 min, stir for 50 min, raise the temperature to 65 °C, soak for 5 h, and then filter;

[0089] Mix the filter residue with a citric acid solution in a mass ratio of 1:15, stir at 66 °C for 70 min, add a lanthanum chloride solution, stir for 3 h, drip a phosphoric acid solution into the solution, and let it stand for 60 min; filter; wash the filter residue with distilled water 5 times, dry it, and superfine pulverize the dried modified cellulose to obtain rare earth hybrid cellulose;

[0090] Mix 65 parts of ethylene-octene copolymer resin, 72 parts of polyethylene resin, 4 parts of vinyltrimethoxysilane, 2 parts of diisopropylbenzene peroxide, and 9 parts of rare earth hybrid cellulose, melt and mix them evenly, and then cast and form a film to obtain the anti-aging layer A;

[0091] The mass concentration of the citric acid solution is 1.3 g / L; the mass concentration of the lanthanum chloride solution is 0.3%; the dosage of the lanthanum chloride solution is 3 times the mass of the filter residue; the concentration of the phosphoric acid solution is 0.3%, and the dosage is 1.3 times the mass of the cellulose;

[0092] Ⅲ Prepare the anti-aging layer B

[0093] Mix the aforementioned calcium and magnesium hybrid cellulose and rare earth hybrid cellulose in a mass ratio of 6:1.4, add them to the film body in an amount of 6%, and perform subsequent operations according to the film body preparation steps of the strengthening layer; press, cool, and wind up each layer to form a lightweight photovoltaic front panel film.

[0094] Example 3

[0095] A lightweight front panel film for photovoltaic applications, which is successively composed of a strengthening layer, an anti-aging layer A, and an anti-aging layer B. The thickness ratio of the strengthening layer, anti-aging layer A, and anti-aging layer B is 2:1:4.

[0096] The preparation method of the lightweight front panel film for photovoltaic applications in this example is as follows:

[0097] Ⅰ. Preparation of the strengthening layer

[0098] (1) Preparation of refined cellulose

[0099] Mix and crush the green flax and abaca into a slurry, grind it at 42°C for 20 - 30 min, add 6 times the mass of the slurry of clear water and soak it at 57°C for 23 min. Raise the temperature to the boiling point, boil for 15 min, wait for the temperature to drop to 70°C, keep warm for 3 h, and filter to obtain the filter residue for standby.

[0100] Mix the above filter residue with ethanol at a mass ratio of 1:13, heat to 44°C, add propanol to the mixed system and stir for 30 min; lower the temperature to 25°C, add chloroform, seal and shake for 50 min, and filter. Keep the filter residue for standby;

[0101] The mass ratio of the flax and abaca is 2:1; the dosage of the propanol is 1 / 4 of the ethanol; the dosage of the chloroform is 1 / 3 of the ethanol;

[0102] Mix the above filter residue with an alkali solution at a mass ratio of 1:18, heat it to boiling with microwave, keep warm for 50 min, lower the temperature to room temperature, put it in a freezer at -30°C for 30 h; take it out, heat it to 80°C with microwave and keep warm for 70 min, filter, and wash the filter residue with clear water 3 times and dry it for standby;

[0103] The alkali solution is a sodium hydroxide solution with a mass fraction of 7.9%; the microwave power is 800 W; the temperature of the freezer is -30°C;

[0104] Mix the above filter residue with hydrochloric acid at a mass ratio of 1:14, stir for 20 min, add phosphoric acid and stir for 3 h, dilute the solution 3 times, continue to stir for 5 h, and then wash it 3 times with distilled water and concentrate it under reduced pressure and dry it;

[0105] The concentration of the hydrochloric acid is 1.5 mol / L; the concentration of the phosphoric acid is 1.2 mol / L; the dosage of the phosphoric acid is 8% of the hydrochloric acid;

[0106] (2) Modification of cellulose

[0107] Mix the refined cellulose in the previous step with water at a mass ratio of 1:8, introduce ozone, let it stand for 30 min, raise the temperature to 45°C, and add potassium sulfate to obtain solution A;

[0108] Mix acrylamide and ethanol in a mass ratio of 1:20 to obtain solution B;

[0109] Mix N,N'-methylenebisacrylamide and water in a mass ratio of 1:25 to obtain solution C;

[0110] Add 2 parts of solution C to 10 parts of solution A, mix evenly, and under ultrasonic oscillation, drop 15 parts of solution B into the aforementioned solution. The obtained reactant is rinsed with ethanol and dried, soaked in a calcium and magnesium solution for 30 min, and then filtered and ultra-finely pulverized to obtain calcium and magnesium hybrid cellulose;

[0111] The concentration of ozone in the solution is 2.3 mg / L; the dosage of potassium sulfate is 6% of the mass of the refined cellulose; the calcium and magnesium solution is composed of calcium chloride, magnesium chloride, and water mixed in a mass ratio of 10:2:211;

[0112] (3) Preparation of the film body

[0113] Mix 60 parts of ethylene-octene copolymer resin, 60 parts of polyethylene resin, 4 parts of vinyltrimethoxysilane, 1 part of ditert-butylperoxide diisopropylbenzene, and 8 parts of the calcium and magnesium hybrid cellulose prepared in the previous step, melt and mix them evenly, and cast a film;

[0114] Ⅱ Preparation of anti-aging layer A

[0115] Prepare refined cellulose according to the steps of the strengthening layer (1). Mix 13 parts of refined cellulose and 120 parts of deionized water, heat to 60 °C, add 1 part of 1-aminooctadecane, mix evenly, soak for 30 min, stir for 30 min, raise the temperature to 65 °C, soak for 5 h, and filter;

[0116] Mix the filter residue and the citric acid solution in a mass ratio of 1:15, stir at 58 °C for 70 min, add the lanthanum chloride solution, stir for 2 h, drop the phosphoric acid solution into the solution, and let it stand for 60 min; filter; wash the filter residue with distilled water 3 times, dry it, and ultra-finely pulverize the dried modified cellulose to obtain rare earth hybrid cellulose;

[0117] Mix 59 parts of ethylene-octene copolymer resin, 72 parts of polyethylene resin, 1 part of vinyltrimethoxysilane, 2 parts of ditert-butylperoxide diisopropylbenzene, and 9 parts of rare earth hybrid cellulose, melt and mix them evenly, and cast a film to obtain anti-aging layer A;

[0118] The mass concentration of the citric acid solution is 1.3 g / L; the mass concentration of the lanthanum chloride solution is 0.1%; the dosage of the lanthanum chloride solution is 3 times the mass of the filter residue; the concentration of the phosphoric acid solution is 0.1%, and the dosage is 1.3 times the mass of the cellulose;

[0119] Ⅲ Preparation of anti-aging layer B

[0120] Mix the aforementioned calcium-magnesium hybrid cellulose and rare-earth hybrid cellulose at a mass ratio of 6:1.4, add it to the film body at a dosage of 3%, and then perform subsequent operations according to the film preparation steps of the strengthening layer; press, cool, and wind each layer into shape to obtain a lightweight front panel film for photovoltaic applications.

[0121] Setting of comparative examples:

[0122]

[0123]

[0124] Test examples

[0125] Prepare film materials according to Examples 1-3 and Comparative Examples 1-8, test the tensile strength according to GB / T 1040-2006, and test the water vapor transmission rate according to GB / T 26253-2010. The specific results are shown in the following table:

[0126] Tensile strength / MPa <![CDATA[Water vapor transmission rate (g·cm -2 ·d -1 )]]> Example 1 199.45 1.01 Example 2 185.97 1.06 Example 3 185.02 1.02 Comparative Example 1 141.15 1.53 Comparative Example 2 153.40 1.43 Comparative Example 3 159.23 1.35 Comparative Example 4 162.29 1.49

[0127] It can be seen from the table that using the solution of the present invention effectively improves the tensile strength of the film, reduces the water vapor transmission rate, and enables the film to have good shielding and protective properties. After the film is assembled onto the component and actually used for 7 months, re-testing shows that the tensile strength of the films in Examples 1-3 exceeds 175.33 MPa, and the water vapor transmission rate is lower than 1.13 g·cm -2 ·d -1 ; the tensile strength of the films in Comparative Examples 1-4 is lower than 133.97 MPa, and the water vapor transmission rate is higher than 1.63 g·cm -2 ·d -1 ; it can be seen that the film of the present invention has better environmental tolerance.

Claims

1. A preparation method of a lightweight front panel film for photovoltaic applications, characterized in that, Including: Ⅰ Preparation of the strengthening layer: (1) Preparation of refined cellulose Mix and crush the green flax and abaca into slurry, grind it at 40 - 43 °C for 20 - 30 min, add 50 - 60 °C clear water 5 - 8 times the mass of the slurry and soak for 20 - 30 min, raise the temperature to the boiling point, boil for 10 - 15 min, wait for the temperature to drop to 70 - 75 °C, keep warm for 2 - 3 h, and filter to obtain the filter residue for standby; Mix the above filter residue with ethanol according to a mass ratio of 1:10 - 13, heat to 44 - 47 °C, add propanol to the mixing system and stir for 20 - 30 min; lower the temperature to 25 - 28 °C, add chloroform, seal and shake for 40 - 50 min, filter, and keep the filter residue for standby; Mix the above filter residue with lye according to a mass ratio of 1:15 - 18, heat to boiling with microwave, keep warm for 50 - 80 min, lower the temperature to room temperature, put it into the freezer and freeze for 20 - 30 h; take it out and heat to 80 - 85 °C with microwave and keep warm for 70 - 88 min, filter, and wash the filter residue with clear water 3 - 5 times and dry for standby; Mix the above filter residue with hydrochloric acid according to a mass ratio of 1:12 - 14, stir for 20 - 30 min, add phosphoric acid and stir for 2 - 3 h, dilute the solution 3 - 5 times, continue to stir for 3 - 5 h, and then wash with distilled water 2 - 3 times and concentrate under reduced pressure and dry; [[ID=Z]]The concentration of the hydrochloric acid is 1.5 - 1.9 mol / L; the concentration of the phosphoric acid is 1 - 1.2 mol / L; the dosage of the phosphoric acid is 8 - 10% of the hydrochloric acid; (2) Cellulose modification Mix the refined cellulose in the previous step with water according to a mass ratio of 1:6 - 8, introduce ozone, let it stand for 30 - 40 min, raise the temperature to 43 - 45 °C, and add potassium sulfate to obtain solution A; Mix acrylamide with ethanol according to a mass ratio of 1:15 - 20 to obtain solution B; Mix N,N'-methylenebisacrylamide with water according to a mass ratio of 1:25 - 30 to obtain solution C; Add 1 - 2 parts of solution C to 10 parts of solution A, mix evenly, and under ultrasonic vibration, drop 15 - 20 parts of solution B into the aforementioned solution. The obtained reactant is washed and dried with ethanol, soaked in a calcium and magnesium solution mixture for 20 - 30 min, and filtered and superfine pulverized to obtain calcium and magnesium hybrid cellulose; (3) Preparation of the film body Mix 50 - 60 parts of ethylene - octene copolymer resin, 60 - 70 parts of polyethylene resin, 1 - 4 parts of vinyltrimethoxysilane, 1 - 2 parts of di - tert - butyl peroxide diisopropylbenzene, and 5 - 8 parts of the calcium and magnesium hybrid cellulose prepared in the previous step, melt and mix them evenly, and cast a film; Ⅱ Preparation of the anti - aging layer A Prepare refined cellulose according to the steps of the strengthening layer (1). Mix 10 - 13 parts of refined cellulose and 120 - 150 parts of deionized water, heat to 50 - 60 °C, add 1 - 2 parts of 1 - aminooctadecane, mix evenly, soak for 20 - 30 min, stir for 30 - 50 min, raise the temperature to 63 - 65 °C, soak for 3 - 5 h, and filter; Mix the filter residue and citric acid solution at a mass ratio of 1:15, stir at 58 - 66 °C for 50 - 70 min, add lanthanum chloride solution, stir for 2 - 3 h, drop phosphoric acid solution into the solution and let it stand for 50 - 60 min; filter; wash the filter residue with distilled water 3 - 5 times, dry it, and ultrafinely pulverize the dried modified cellulose to obtain rare earth hybrid cellulose; Mix 55 - 65 parts of ethylene - octene copolymer resin, 68 - 72 parts of polyethylene resin, 1 - 4 parts of vinyltrimethoxysilane, 1 - 2 parts of ditert - butylperoxide diisopropylbenzene, and 6 - 9 parts of rare earth hybrid cellulose evenly and melt them, and cast a film to obtain the anti - aging layer A; The mass concentration of the citric acid solution is 0.8 - 1.3 g / L; the mass concentration of the lanthanum chloride solution is 0.1 - 0.3%; the dosage of the lanthanum chloride solution is 2 - 3 times the mass of the filter residue; the concentration of the phosphoric acid solution is 0.1 - 0.3%, and the dosage is 1 - 1.3 times the mass of the cellulose; Ⅲ Prepare the anti - aging layer B Mix the aforementioned calcium - magnesium hybrid cellulose and rare earth hybrid cellulose at a mass ratio of 6:1 - 1.4, add it to the film body at a dosage of 3 - 6%, and perform subsequent operations according to the film preparation steps of the reinforcement layer; press, cool, and wind each layer into a roll to obtain the lightweight photovoltaic front panel film; The thickness ratio of the reinforcement layer, anti - aging layer A, and anti - aging layer B is 1 - 2:1 - 3:1 - 4.

2. The preparation method of the lightweight front panel film for photovoltaic according to claim 1, wherein The mass ratio of the flax and abaca is 1 - 2:2 - 4.

3. The preparation method of the lightweight front panel film for photovoltaic according to claim 1, wherein The dosage of the propanol is 1 / 5 - 1 / 4 of that of the ethanol.

4. The preparation method of the lightweight photovoltaic front panel film according to claim 1, wherein, The dosage of the chloroform is 1 / 4 - 1 / 3 of that of the ethanol.

5. The preparation method of the lightweight photovoltaic front panel film according to claim 1, characterized in that, The alkali solution is a sodium hydroxide solution with a mass fraction of 5.6 - 7.9%.

6. The preparation method of the lightweight photovoltaic front panel film according to claim 1, wherein, The microwave power is 800 - 900 W.

7. The preparation method of the lightweight photovoltaic front panel film according to claim 1, characterized in that, The temperature of the freezer is - 20 - 30 °C.

8. The preparation method of the lightweight photovoltaic front panel film according to claim 1, wherein, The concentration of ozone in the solution is 1.8 - 2.3 mg / L.

9. The preparation method of the lightweight photovoltaic front panel film according to claim 1, characterized in that, The dosage of potassium sulfate is 6 - 8% of the mass of the refined cellulose; the calcium - magnesium solution is composed of calcium chloride, magnesium chloride, and water mixed at a mass ratio of 10:1 - 2:200 - 300.

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