A PVB film, its preparation method and application

Abstract

The present invention discloses a PVB film and its preparation method and application. A PVB film comprises the following raw materials in parts by mass for preparation: 100 parts of PVB resin, 30 - 40 parts of plasticizer, 0.4 - 1.2 parts of ultraviolet absorber, 0.2 - 2 parts of light stabilizer, 0.2 - 2 parts of antioxidant, and 0.0005 - 0.005 parts of coupling agent; the plasticizer comprises triethylene glycol diisooctylate and trioctyl phosphate, and the mass ratio of triethylene glycol diisooctylate to trioctyl phosphate is (2 - 4):1. The PVB film of the present invention has a relatively high volume resistivity and good weather resistance. Its insulation performance does not significantly decline under long-term outdoor low-temperature and high-humidity environments, and it has excellent anti-aging performance and good encapsulation effect. It can be used for the encapsulation of photovoltaic modules and can ensure the long-term high-efficiency operation of photovoltaic modules.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic module encapsulation materials, and particularly relates to a PVB film and its preparation method and application. Background Art

[0002] In the context of the increasing global energy costs, the photovoltaic industry is gradually emerging. The glue commonly used for encapsulating ordinary photovoltaic modules is generally EVA. However, it also has undeniable disadvantages: poor anti-aging performance, easy yellowing of the glue film, difficult to meet the 25-year service life, unable to have the same service life as the module, and the yellowing of EVA will affect the aesthetics of the module and the power generation of the system. The PVB film has characteristics such as transparency, heat resistance, cold resistance, moisture resistance, and high mechanical strength, and has been maturely applied to the encapsulation of solar photovoltaic modules. The domestic glass curtain wall specification also clearly puts forward the regulation of "applying PVB". The BIPV photovoltaic module using PVB instead of EVA can achieve a longer service life.

[0003] PVB has excellent properties on laminated safety glass. For example, optical transparency, adjustable glass adhesion, resistance to strong impact, resistance to ultraviolet rays, and temperature stability. For safety reasons, more and more countries are beginning to use only double-glass photovoltaic modules with PVB film as the encapsulation material. As a solar cell encapsulation material, in addition to having good mechanical properties, it must also have good anti-aging performance and good insulation performance. Therefore, excellent anti-aging performance and thermal insulation are the keys to ensuring the encapsulation quality and long-term use performance of solar cells. However, due to the affinity of PVB for water, under long-term high-temperature and high-humidity conditions, the absorbed water will cause its insulation to drop sharply, resulting in unqualified electrical performance tests of photovoltaic modules, such as excessive wet leakage current and excessive power attenuation.

[0004] Therefore, in order to meet the application of PVB film in photovoltaic module encapsulation, it is necessary to further improve the volume resistivity and weather resistance. Summary of the Invention

[0005] In order to overcome the problem that the existing PVB film cannot meet the application in photovoltaic module encapsulation, one of the purposes of the present invention is to provide a PVB film; the second purpose of the present invention is to provide a preparation method of this PVB film; the third purpose of the present invention is to provide an application of this PVB film.

[0006] In order to achieve the above purposes, the technical solutions adopted by the present invention are:

[0007] The first aspect of the present invention provides a PVB film, which comprises the following raw materials for preparation in parts by mass: 100 parts of PVB resin, 30 - 40 parts of plasticizer, 0.4 - 1.2 parts of ultraviolet absorber, 0.2 - 2 parts of light stabilizer, 0.2 - 2 parts of antioxidant, and 0.0005 - 0.005 parts of coupling agent;

[0008] The plasticizer comprises triethylene glycol diisooctoate and triphenyl phosphate, and the mass ratio of triethylene glycol diisooctoate to triphenyl phosphate is (2 - 4):1.

[0009] The inventors have found through research that by adding a plasticizer with a relatively strong polarity and more intramolecular branches, it can be used as a plasticizer for the PVB film encapsulating photovoltaic modules. Compared with using only triethylene glycol diisooctoate as a plasticizer, the volume resistivity of the PVB film can be significantly increased.

[0010] Although triphenyl phosphate has good low-temperature flexibility and good electrical insulation performance, its migration is large and its plasticizing performance is poor. Therefore, its application is limited and the addition amount should not be too large. It is only used as an auxiliary plasticizer in combination with the main plasticizer.

[0011] Preferably, in this PVB film, the plasticizer may further comprise at least one of DEHP (di(2-ethylhexyl) phthalate), DOP (dioctyl phthalate), DOTP (dioctyl terephthalate), and DBP (dibutyl phthalate).

[0012] Preferably, in this PVB film, the content of PVB resin in the PVB film is 70 - 75 wt%.

[0013] Preferably, in this PVB film, the hydroxyl content of the PVB resin is 16 - 22 wt%; more preferably, the hydroxyl content of the PVB resin is 18 - 20 wt%.

[0014] Preferably, in this PVB film, the ultraviolet absorber comprises at least one of benzophenone-based, benzotriazole-based, and triazine-based ultraviolet absorbers; more preferably, the ultraviolet absorber is a benzotriazole-based ultraviolet absorber; still more preferably, the ultraviolet absorber comprises at least one of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (UV-P), (2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole (UV-326), 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole (UV-327), and 2-(2'-hydroxy-3',5'-dipentylphenyl)benzotriazole (UV-328); even more preferably, the ultraviolet absorber is UV-326.

[0015] Preferably, in this PVB film, the light stabilizer is a hindered amine light stabilizer; the light stabilizer includes at least one of 4-benzoyloxy-2,2,6,6-tetramethylpiperidine (light stabilizer 744), bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (Tinuvin 770), light stabilizer LA-68, light stabilizer LA-62, and Chimassorb 944; more preferably, the light stabilizer is light stabilizer 744.

[0016] Preferably, in this PVB film, the antioxidant is a mixture of a hindered phenol antioxidant and a phosphite antioxidant; the hindered phenol antioxidant includes at least one of 2,6-di-tert-butyl-p-cresol (BHT), n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (antioxidant 1076), pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (antioxidant 1010), N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamide) (antioxidant 1098), and triethylene glycol bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate] (antioxidant 245); the phosphite antioxidant includes at least one of diphenyl isooctyl phosphite (ODPP), tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168), bisphenol A phosphite, and triphenyl phosphite (TPP); more preferably, the mass ratio of the hindered phenol antioxidant to the phosphite antioxidant is 1:(0.5 - 2); even more preferably, the mass ratio of the hindered phenol antioxidant to the phosphite antioxidant is 1:(0.8 - 1.2).

[0017] More preferably, the antioxidant is a composition of antioxidant 1010 and antioxidant 168.

[0018] Preferably, in this PVB film, the coupling agent is a silane coupling agent; the silane coupling agent includes at least one of γ-glycidoxypropyltriethoxysilane (A-187), β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (A-186), γ-(methacryloyloxy)propyltrimethoxysilane (KH-570), and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane (A-1120).

[0019] The PVB film of the present invention may also contain additives such as flame retardants, antistatic agents, pigments, dyes, surfactants, and fluorescent whitening agents as needed. These additives can be used alone or in combination of two or more.

[0020] The second aspect of the present invention provides a method for preparing the above PVB film, including the following steps:

[0021] 1) Mix the plasticizer components to obtain a plasticizer mixture;

[0022] 2) Mix the ultraviolet absorber, light stabilizer, antioxidant, coupling agent with the plasticizer mixture, then add PVB resin, and perform plasticizing extrusion through an extruder to obtain the PVB film.

[0023] Preferably, in the preparation method of the PVB film, in step 2), the temperature of the plasticizing extrusion is 150 - 170 °C; more preferably, the temperature of the plasticizing extrusion is 155 - 165 °C.

[0024] The third aspect of the present invention provides the application of the above-mentioned PVB film in the preparation of photovoltaic module encapsulation materials.

[0025] The beneficial effects of the present invention are:

[0026] The PVB film of the present invention has a high volume resistivity and good weather resistance. Its insulation performance does not significantly decrease under long-term outdoor low-temperature and high-humidity environments, and it has excellent aging resistance and good encapsulation effect. It can be used as a photovoltaic module encapsulation material, which can ensure the long-term high-efficiency operation of photovoltaic modules.

[0027] For the PVB film of the present invention, triethylene glycol diisooctoate (3GO) plasticizer is used as the main plasticizer, and trioctyl phosphate (TOP) with a strong polarity and multi-molecular branches is used as the auxiliary plasticizer. While significantly improving the volume resistivity of the PVB film, the light transmittance and bonding strength are not affected, and the electrical properties of the encapsulation film are significantly improved. At the same time, a hindered amine light stabilizer is added and used in combination with a phenolic antioxidant and a phosphite auxiliary antioxidant. The synergistic effect significantly improves the weather resistance of the PVB film, which can ensure the long-term operation of photovoltaic modules in harsh outdoor environments. Specific Embodiments

[0028] The following further details the content of the present invention through specific examples. The raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial channels or can be obtained by existing technical methods without special instructions. Unless otherwise specified, the test or measurement methods are conventional methods in the art.

[0029] In the following examples and comparative examples, "parts" all refer to "parts by mass".

[0030] Example 1

[0031] The specific implementation steps of the preparation method of the PVB film in this example are as follows:

[0032] 1) Mix the plasticizers: Mix 75 parts of triethylene glycol diisooctoate plasticizer with 25 parts of trioctyl phosphate plasticizer evenly.

[0033] 2) Dissolve the following raw materials in parts by weight in a mixed plasticizer of triethylene glycol diisooctate and trioctyl phosphate: 0.8 part of ultraviolet absorber UV-326, 0.8 part of light stabilizer 744, 0.5 part of antioxidant 1010, 0.5 part of antioxidant 168, and 0.003 part of silane coupling agent A-187.

[0034] 3) Plasticize and extrude 38 parts of the composition obtained in step 2) above and 100 parts of PVB resin powder through a twin-screw extruder at 160 °C to obtain the PVB film for photovoltaic module encapsulation.

[0035] Example 2

[0036] The specific implementation steps of the preparation method of the PVB film in this example are as follows:

[0037] 1) Mix the plasticizers: Mix 80 parts of triethylene glycol diisooctate plasticizer and 20 parts of trioctyl phosphate plasticizer evenly.

[0038] 2) Dissolve the following raw materials in parts by weight in a mixed plasticizer of triethylene glycol diisooctate and trioctyl phosphate: 0.8 part of ultraviolet absorber UV-326, 0.8 part of light stabilizer 744, 0.5 part of antioxidant 1010, 0.5 part of antioxidant 168, and 0.003 part of silane coupling agent A-187.

[0039] 3) Plasticize and extrude 38 parts of the composition obtained in step 2) above and 100 parts of PVB resin powder through a twin-screw extruder at 160 °C to obtain the PVB film for photovoltaic module encapsulation.

[0040] Example 3

[0041] The specific implementation steps of the preparation method of the PVB film in this example are as follows:

[0042] 1) Mix the plasticizers: Mix 67 parts of triethylene glycol diisooctate plasticizer and 33 parts of trioctyl phosphate plasticizer evenly.

[0043] 2) Dissolve the following raw materials in parts by weight in a mixed plasticizer of triethylene glycol diisooctate and trioctyl phosphate: 0.8 part of ultraviolet absorber UV-326, 0.8 part of light stabilizer 744, 0.5 part of antioxidant 1010, 0.5 part of antioxidant 168, and 0.003 part of silane coupling agent A-187.

[0044] 3) Plasticize and extrude 38 parts of the composition obtained in step 2) above and 100 parts of PVB resin powder through a twin-screw extruder at 160 °C to obtain the PVB film for photovoltaic module encapsulation.

[0045] Comparative Example 1

[0046] The specific implementation steps of the preparation method of the PVB film in this comparative example are as follows:

[0047] 1) Mix plasticizers: Mix 67 parts of triethylene glycol diisooctylate plasticizer with 33 parts of trioctyl phosphate plasticizer evenly.

[0048] 2) Dissolve the following raw materials in parts by weight in the mixed plasticizer of triethylene glycol diisooctylate and trioctyl phosphate: 0.5 part of antioxidant 1010, 0.5 part of antioxidant 168, and 0.003 part of silane coupling agent A-187.

[0049] 3) Plasticize and extrude 38 parts of the composition obtained in step 2) above and 100 parts of PVB resin powder through a twin-screw extruder at 160 °C to obtain the PVB film for photovoltaic module encapsulation.

[0050] Comparative Example 2

[0051] The specific implementation steps of the preparation method of the PVB film in this comparative example are as follows:

[0052] 1) Mix plasticizers: Mix 67 parts of triethylene glycol diisooctylate plasticizer with 33 parts of trioctyl phosphate plasticizer evenly.

[0053] 2) Dissolve the following raw materials in parts by weight in the mixed plasticizer of triethylene glycol diisooctylate and trioctyl phosphate: 0.8 part of ultraviolet absorber UV-326, 0.8 part of light stabilizer 744, and 0.003 part of silane coupling agent A-187.

[0054] 3) Plasticize and extrude 38 parts of the above-mentioned mixed plasticizer composition of triethylene glycol diisooctylate and trioctyl phosphate and 100 parts of PVB resin powder through a twin-screw extruder at 160 °C to obtain the PVB film for photovoltaic module encapsulation.

[0055] Comparative Example 3

[0056] The specific implementation steps of the preparation method of the PVB film in this comparative example are as follows:

[0057] 1) Dissolve the following raw materials in parts by weight in 100 parts of triethylene glycol diisooctylate plasticizer: 0.8 part of ultraviolet absorber UV-326, 0.8 part of light stabilizer 744, 0.5 part of antioxidant 1010, 0.5 part of antioxidant 168, and 0.003 part of silane coupling agent A-187.

[0058] 2) Plasticize and extrude 38 parts of the above-mentioned triethylene glycol diisooctylate plasticizer composition and 100 parts of PVB resin powder through a twin-screw extruder at 160 °C to obtain the PVB film for photovoltaic module encapsulation.

[0059] Comparative Example 4

[0060] The specific implementation steps of the preparation method of the PVB film in this comparative example are as follows:

[0061] 1) Mix plasticizers: Mix 57 parts of triethylene glycol diisooctylate plasticizer and 43 parts of tributyl phosphate plasticizer evenly.

[0062] 2) Dissolve the following raw materials in the mixed plasticizer of triethylene glycol diisooctylate and tributyl phosphate: 0.8 part of ultraviolet absorber UV-326, 0.5 part of antioxidant 1010, 0.5 part of antioxidant 168, 0.8 part of light stabilizer 744, and 0.003 part of silane coupling agent A-187.

[0063] 3) Plasticize and extrude 38 parts of the composition obtained in step 2) above and 100 parts of PVB resin powder through a twin-screw extruder at 160 °C to obtain the PVB film for photovoltaic module encapsulation.

[0064] Performance testing

[0065] (1) Volume resistivity test

[0066] Determine the volume resistivity of the PVB film according to GB / T 1410-2006. During the test, charge for 15 s and read the data after 60 s.

[0067] (2) Aging resistance test

[0068] Evaluate whether there are changes in the appearance quality and mechanical properties of the obtained PVB film synthetic safety glass after being irradiated by ultraviolet rays for a certain period of time.

[0069] Equipment: Irradiation resistance test machine, electronic universal testing machine

[0070] Irradiation light source: Ozone-free quartz tube mercury vapor arc lamp. The axis of the lamp shell should be vertical. The nominal size of the lamp is 360 mm in length, 9.5 mm in diameter, the arc length is 300 mm ± 14 mm, and the working power is 750 w ± 50 w.

[0071] Place three 76×300 mm test pieces on the device 230 mm away from the lamp axis, and make its length direction parallel to the lamp axis. Rotate around the irradiation source set at the axis at a speed of 1-5 r / min to ensure uniform irradiation. Keep the temperature of the specimen at 45 ± 5 °C throughout the test. The irradiation time is 10 days. After irradiation, place the specimen on a white background and observe whether there are changes in the appearance of the specimen. Use an electronic universal testing machine to detect the tensile strength and elongation at break of the specimen after aging resistance.

[0072] (3) Plasticizer precipitation

[0073] Place the PVB film samples of the experimental examples in a dryer containing sulfuric acid in turn. After placing for 5 days, take them out and weigh their masses m in turn1 。Then, the dried (after weighing) samples are successively placed in a desiccator filled with water for 7 days. The water on the surface of the samples is blotted dry with filter paper, and then dried in a sulfuric acid desiccator for 5 days. After that, the samples are taken out and weighed successively as m 2 。The performance test results are shown in Table 1 below.

[0074] Plasticizer exudation amount = (m 1 - m 2 ) / m 1 × 100%. The average value of the plasticizer exudation amounts of four samples is taken as the test result.

[0075] Table 1

[0076]

[0077] In the present invention, due to the addition of trioctyl phosphate plasticizer, the volume resistivity of the PVB film for photovoltaic module encapsulation is effectively improved; a hindered amine light stabilizer is also added to the film system. This light stabilizer can scavenge free radicals and cut off the autoxidation chain reaction, and has a synergistic effect when used in combination with an ultraviolet absorber and an antioxidant, significantly improving the weather resistance of the PVB film. It can be seen from Comparative Example 4 that trioctyl phosphate plasticizer can increase the volume resistivity, but it cannot be added too much. When added too much, the compatibility between the plasticizer and the resin powder becomes poor and exudation occurs.

[0078] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A PVB film, characterized in that, it comprises the following raw materials for preparation in parts by mass: 100 parts of PVB resin, 30 - 40 parts of plasticizer, 0.4 - 1.2 parts of ultraviolet absorber, 0.2 - 2 parts of light stabilizer, 0.2 - 2 parts of antioxidant, 0.0005 - 0.005 parts of coupling agent; the plasticizer is a mixture of triethylene glycol diisooctoate and trioctyl phosphate with a mass ratio of (2 - 4):

1.

2. The PVB film according to claim 1, characterized in that, the content of PVB resin in the PVB film is 70 - 75 wt%.

3. The PVB film according to claim 1 or 2, characterized in that, the hydroxyl content of the PVB resin is 16 - 22 wt%.

4. The PVB film according to claim 1, characterized in that, the ultraviolet absorber includes at least one of benzophenone - type, benzotriazole - type, and triazine - type ultraviolet absorbers.

5. The PVB film according to claim 1, characterized in that, the light stabilizer is a hindered amine light stabilizer; the light stabilizer includes at least one of 4 - benzoyloxy - 2,2,6,6 - tetramethylpiperidine, bis(2,2,6,6 - tetramethyl - 4 - piperidyl) sebacate, light stabilizer LA - 68, light stabilizer LA - 62, and Chimassorb 944.

6. The PVB film according to claim 1, characterized in that, the antioxidant is a mixture of a hindered phenol antioxidant and a phosphite antioxidant.

7. The PVB film according to claim 1, characterized in that, the coupling agent is a silane coupling agent; the silane coupling agent includes at least one of γ - glycidoxypropyltriethoxysilane, β - (3,4 - epoxycyclohexyl) - ethyltrimethoxysilane, γ - (methacryloyloxy)propyltrimethoxysilane, and N - β - (aminoethyl) - γ - aminopropyltrimethoxysilane.

8. The preparation method of the PVB film according to any one of claims 1 to 7, characterized in that, it comprises the following steps: 1) Mix the plasticizer components to obtain a plasticizer mixture; 2) Mix the ultraviolet absorber, light stabilizer, antioxidant, coupling agent with the plasticizer mixture, then add the PVB resin, and perform plasticizing extrusion through an extruder to obtain the PVB film.

9. The preparation method of the PVB film according to claim 8, characterized in that, in step 2), the temperature of the plasticizing extrusion is 150 - 170 °C.

10. The application of the PVB film according to any one of claims 1 to 7 in the preparation of photovoltaic module encapsulation materials.

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