EVA (Ethylene Vinyl Acetate) photovoltaic adhesive film anti-aging additive as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of photovoltaic adhesive film anti-aging, and provides an EVA photovoltaic adhesive film anti-aging auxiliary agent and a preparation method and application thereof.The EVA photovoltaic adhesive film anti-aging auxiliary agent is prepared through the steps that after a certain amount of peroxide initiator, a reaction type hindered amine light stabilizer containing carbon-carbon double bonds and EVA resin are evenly mixed, the mixture is extruded, and the EVA photovoltaic adhesive film anti-aging auxiliary agent is obtained; and reacting and extruding in a double-screw extruder to obtain the product. The preparation method of the anti-aging auxiliary agent for the EVA photovoltaic adhesive film provided by the invention is simple, mass production can be realized, and the anti-aging performance of the EVA photovoltaic adhesive film prepared by adopting the anti-aging auxiliary agent for the EVA photovoltaic adhesive film is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of anti-aging of photovoltaic films, and particularly relates to an anti-aging additive for EVA photovoltaic films, a preparation method thereof, and an application thereof. Background Art

[0002] The anti-aging ability is one of the important properties of polymer materials. Especially in the photovoltaic field, it is one of the key factors for the long-term stable use of photovoltaic films in photovoltaic modules. During the use of photovoltaic modules, they are directly exposed to sunlight for a long time, and the photovoltaic films are prone to aging problems such as thermal-oxidative aging, discoloration, and delamination. After the photovoltaic film fails, the following main problems exist: The ketene structure formed by Norrish type II degradation causes the film to turn yellow and brown; after the film discolors, the light transmittance decreases, resulting in optical decoupling and attenuation of the photovoltaic conversion power, and even delamination due to the decrease in the adhesion strength; especially EVA (ethylene-vinyl acetate copolymer) with vinyl acetate groups will produce acetic acid under the action of light and heat, and the acetic acid further autocatalyzes to accelerate the aging of the EVA film, while corroding other metal components in the photovoltaic module, leading to the failure of the photovoltaic module.

[0003] In order to improve the aging resistance of photovoltaic films, anti-aging additives must be added to the photovoltaic film formulation. However, some existing anti-aging additives still have insufficient anti-aging effects during the long-term light exposure of photovoltaic films. Therefore, it is necessary to develop an anti-aging additive for EVA photovoltaic films with more excellent anti-aging effects. Summary of the Invention

[0004] In view of this, the present invention provides an anti-aging additive for EVA photovoltaic films, a preparation method thereof, and an application thereof to improve the anti-aging performance of EVA photovoltaic films.

[0005] To achieve the above object, the technical solution of the present invention is as follows: A preparation method of an anti-aging additive for EVA photovoltaic films includes the following steps: Mix a peroxide initiator, a reactive hindered amine light stabilizer, and an EVA resin evenly by mechanical mixing; then place them in a twin-screw extruder for reaction, and extrude to obtain the anti-aging additive for EVA photovoltaic films; wherein, the reactive hindered amine light stabilizer is a reactive hindered amine light stabilizer containing a carbon-carbon double bond.

[0006] The present invention is further provided that the peroxide initiator is selected from at least one of tert-butyl peroxy-2-ethylhexyl carbonate, tert-amyl peroxy(2-ethylhexyl) carbonate, dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, or 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane.

[0007] The present invention is further configured such that the reactive hindered amine light stabilizer is selected from 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate and / or 2,2,6,6-tetramethyl-4-piperidyl methacrylate.

[0008] The present invention is further configured such that the addition amount of the peroxide initiator is 0.1% - 3.0% of the mass of the EVA resin.

[0009] The present invention is further configured such that the addition amount of the peroxide initiator is 0.5% - 3.0% of the mass of the EVA resin, such as 0.5%, 1.0%, 1.5%, 2.0%, 2.5% or 3.0%.

[0010] Preferably, the addition amount of the peroxide initiator is 1.0% - 3.0% of the mass of the EVA resin.

[0011] The present invention is further configured such that the addition amount of the reactive hindered amine light stabilizer is 1.0% - 10% of the mass of the EVA resin. For example, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0% or 10%.

[0012] The present invention is further configured such that the temperature condition of the twin-screw extruder is 80 - 220 °C.

[0013] The present invention is further configured such that the temperature condition of the twin-screw extruder is as follows: the temperature of the first temperature zone is 80 - 100 °C, the temperature of the second temperature zone is 110 - 130 °C, the temperature of the third to seventh temperature zones is 140 - 220 °C, the temperature of the eighth temperature zone is 100 - 120 °C, and the head temperature is 100 - 120 °C.

[0014] The present invention is further configured such that the main screw rotation speed of the twin-screw extruder is 50 - 500 revolutions per minute, preferably 100 - 400 revolutions per minute.

[0015] The present invention provides an anti-aging aid for EVA photovoltaic encapsulant films prepared by the above preparation method.

[0016] The present invention also provides an EVA photovoltaic encapsulant film, comprising an EVA resin and the anti-aging aid for EVA photovoltaic encapsulant films prepared above, and the addition amount of the anti-aging aid for EVA photovoltaic encapsulant films is 1% - 25% of the mass of the EVA resin.

[0017] The present invention is further configured such that the EVA photovoltaic adhesive film comprises EVA resin, an anti-aging aid for EVA photovoltaic adhesive film, a crosslinking agent, a co-crosslinking agent, and a silane coupling agent; wherein, the addition amount of the anti-aging aid for EVA photovoltaic adhesive film is 1.0% to 20% of the mass of the EVA resin, the addition amount of the crosslinking agent is 1.0% to 3.0% of the total mass of the EVA resin and the anti-aging aid for EVA photovoltaic adhesive film, the addition amount of the co-crosslinking agent is 0.5% to 2.0% of the total mass of the EVA resin and the anti-aging aid for EVA photovoltaic adhesive film, and the addition amount of the silane coupling agent is 0.05% to 1.0% of the total mass of the EVA resin and the anti-aging aid for EVA photovoltaic adhesive film.

[0018] The present invention is further configured such that the crosslinking agent is selected from at least one of tert-butyl peroxy-2-ethylhexyl carbonate, tert-amyl peroxy(2-ethylhexyl) carbonate, dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, or 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane;

[0019] The co-crosslinking agent is selected from at least one of triallyl isocyanurate, trimethylolpropane trimethacrylate, hexanediol dimethacrylate, butanediol dimethacrylate, or ethylene glycol dimethacrylate;

[0020] The silane coupling agent is selected from at least one of γ-(methacryloyloxy)propyltrimethoxysilane, 3-(trimethoxysilyl)propyl methacrylate, vinyltrimethoxysilane, vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, or γ-glycidoxypropyltrimethoxysilane.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts a reactive extrusion method to graft a hindered amine light stabilizer onto the EVA main chain, obtaining a novel anti-aging aid for EVA photovoltaic adhesive film. Due to its special graft structure, it can significantly improve the anti-aging performance of the EVA photovoltaic adhesive film; The preparation method of the anti-aging aid for EVA photovoltaic adhesive film proposed by the present invention is simple, the raw materials are easily available, and it can be mass-produced and applied to improve the anti-aging performance of the EVA photovoltaic adhesive film. Detailed Embodiments

[0022] The following uses specific embodiments to describe the present invention in detail and completely. It should be understood that the described embodiments are only partial embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of the present invention.

[0023] The raw materials used in the following examples were all purchased directly. Among them, the EVA resin was the V2825 product of Jiangsu Sierbang Petrochemical Co., Ltd. The twin-screw extruder used was the Process-11 of ThermoFisher Scientific, and the single-screw extruder was the SY-6219 of Dongguan Shiyan Precision Instruments Co., Ltd.

[0024] Example 1

[0025] (1) Preparation of anti-aging additive for EVA photovoltaic film

[0026] Weigh 100 g of EVA resin, 3 g of 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, and 1 g of 2-ethylhexyl tert-butyl peroxycarbonate. After mechanical mixing for 10 min, they were fed into a twin-screw extruder for reaction, and then extruded and pelletized in a pelletizer to obtain the anti-aging additive for EVA photovoltaic film. In this example, the extrusion and pelletizing conditions of the twin-screw extruder were as follows: the temperatures of the 1st to 8th sections were 90 °C, 120 °C, 160 °C, 160 °C, 170 °C, 160 °C, 140 °C, and 110 °C respectively; the head temperature was 110 °C; the main screw rotation speed was 200 rpm.

[0027] (2) Preparation of EVA photovoltaic film

[0028] Weigh 950 g of EVA resin, 50 g of the anti-aging additive for EVA photovoltaic film prepared in (1) above, 15 g of 2-ethylhexyl tert-butyl peroxycarbonate, 10 g of triallyl isocyanurate, and 1 g of 3-(trimethoxysilyl)propyl methacrylate (silane coupling agent). After mechanical mixing for 20 min, it was cast into a film through a single-screw extruder, and the temperatures of each section of the extruder were set at 60 - 100 °C, thus obtaining an EVA photovoltaic film modified with the anti-aging additive for EVA photovoltaic film.

[0029] Example 2

[0030] Compared with Example 1, the difference is that in the stage of preparing the anti-aging additive for EVA photovoltaic film, the mass of 2-ethylhexyl tert-butyl peroxycarbonate added is 0.5 g.

[0031] Example 3

[0032] Compared with Example 1, the difference is that in the stage of preparing the anti-aging additive for EVA photovoltaic film, the mass of 2-ethylhexyl tert-butyl peroxycarbonate added is 0.1 g.

[0033] Example 4

[0034] Compared with Example 1, the difference lies in that during the preparation of the anti-aging additive for the EVA photovoltaic film, the mass of tert-butyl peroxy-2-ethylhexyl carbonate added is 0.01 g.

[0035] Example 5

[0036] Compared with Example 1, the difference lies in that during the preparation of the anti-aging additive for the EVA photovoltaic film, the mass of tert-butyl peroxy-2-ethylhexyl carbonate added is 3 g.

[0037] Example 6

[0038] Compared with Example 1, the difference lies in that during the preparation of the anti-aging additive for the EVA photovoltaic film, the mass of 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate added is 1 g.

[0039] Example 7

[0040] Compared with Example 1, the difference lies in that during the preparation of the anti-aging additive for the EVA photovoltaic film, the mass of 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate added is 5 g.

[0041] Example 8

[0042] Compared with Example 1, the difference lies in that during the preparation of the anti-aging additive for the EVA photovoltaic film, the mass of 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate added is 10 g.

[0043] Example 9

[0044] Compared with Example 1, the difference lies in that during the preparation of the anti-aging additive for the EVA photovoltaic film, the main screw speed of the twin-screw extruder is 50 revolutions per minute.

[0045] Example 10

[0046] Compared with Example 1, the difference lies in that during the preparation of the anti-aging additive for the EVA photovoltaic film, the main screw speed of the twin-screw extruder is 100 revolutions per minute.

[0047] Example 11

[0048] Compared with Example 1, the difference lies in that during the preparation of the anti-aging additive for the EVA photovoltaic film, the main screw speed of the twin-screw extruder is 400 revolutions per minute.

[0049] Example 12

[0050] Compared with Example 1, the difference lies in that during the preparation of the anti-aging agent for EVA photovoltaic film, the temperatures of the 1st to 8th sections of the twin-screw extruder are respectively: 90 °C, 120 °C, 120 °C, 120 °C, 130 °C, 120 °C, 100 °C, 110 °C; the head temperature is 110 °C.

[0051] Example 13

[0052] Compared with Example 1, the difference lies in that during the preparation of the anti-aging agent for EVA photovoltaic film, the temperatures of the 1st to 8th sections of the twin-screw extruder are respectively: 90 °C, 120 °C, 200 °C, 200 °C, 210 °C, 200 °C, 180 °C, 110 °C; the head temperature is 110 °C.

[0053] Example 14

[0054] Compared with Example 1, the difference lies in that during the preparation of the anti-aging agent for EVA photovoltaic film, the reactive hindered amine light stabilizer is 2,2,6,6-tetramethyl-4-piperidyl methacrylate.

[0055] Example 15

[0056] Compared with Example 1, the anti-aging agent for the prepared EVA photovoltaic film is the same. The difference lies in that during the preparation of the EVA photovoltaic film, the amount of EVA resin used is 990 g, and the amount of the anti-aging agent for the EVA photovoltaic film prepared in step (1) added is 10 g.

[0057] Example 16

[0058] Compared with Example 1, the anti-aging agent for the prepared EVA photovoltaic film is the same. The difference lies in that during the preparation of the EVA photovoltaic film, the amount of EVA resin used is 900 g, and the amount of the anti-aging agent for the EVA photovoltaic film prepared in step (1) added is 100 g.

[0059] Example 17

[0060] Compared with Example 1, the anti-aging agent for the prepared EVA photovoltaic film is the same. The difference lies in that during the preparation of the EVA photovoltaic film, the amount of EVA resin used is 800 g, and the amount of the anti-aging agent for the EVA photovoltaic film prepared in step (1) added is 200 g.

[0061] Example 18

[0062] Compared with Example 1, the difference lies in that during the preparation of the anti-aging agent for EVA photovoltaic film, the peroxide initiator selected is dicumyl peroxide.

[0063] Example 19

[0064] Compared with Example 1, the difference lies in that in the stage of preparing the anti-aging aid for the EVA photovoltaic film, the peroxide initiator selected is 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0065] Example 20

[0066] Compared with Example 1, the difference lies in that in the stage of preparing the anti-aging aid for the EVA photovoltaic film, the peroxide initiator selected is 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane.

[0067] Comparative Example 1

[0068] Compared with Example 1, the difference lies in that instead of using the method described in the present invention to prepare the anti-aging aid for the EVA photovoltaic film, a hindered amine light stabilizer is directly added during the preparation of the EVA photovoltaic film. The preparation process of the EVA photovoltaic film in this comparative example is as follows:

[0069] Weigh 1 kg of EVA, 1.5 g of 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, 15 g of tert-butyl peroxycarbonate-2-ethylhexyl, 10 g of triallyl isocyanurate, and 1 g of 3-(trimethoxysilyl)propyl methacrylate. After mechanical mixing for 20 minutes, it is cast into a film through a single-screw extruder. The temperature settings of each section of the extruder are the same as in Example 1, which is 60-100 °C, and the EVA photovoltaic film containing a hindered amine is obtained.

[0070] Comparative Example 2

[0071] Compared with Comparative Example 1, the difference lies in that 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate is replaced with 2,2,6,6-tetramethyl-4-piperidyl methacrylate.

[0072] Comparative Example 3

[0073] Compared with Example 1, the difference lies in that in the stage of preparing the anti-aging aid for the EVA photovoltaic film, the mass of tert-butyl peroxycarbonate-2-ethylhexyl added is 5 g.

[0074] Comparative Example 4

[0075] Compared with Example 1, the difference lies in that in the stage of preparing the anti-aging aid for the EVA photovoltaic film, the mass of 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate added is 0.5 g.

[0076] Comparative Example 5

[0077] Compared with Comparative Example 1, the difference lies in that 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate is replaced with bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, a commonly used hindered amine light stabilizer in the art. However, since this hindered amine light stabilizer does not have a reactive group, it cannot be applied to the technical solution of the present invention.

[0078] Performance Evaluation

[0079] (1) Peel Strength Test

[0080] Take two pieces of EVA photovoltaic films prepared in each of the above-mentioned examples and comparative examples, one piece of ultra-white embossed tempered glass with a thickness of 3.2 mm, and one piece of flexible backsheet. Stack them in the order of glass / EVA film (two pieces) / flexible backsheet, put them into a vacuum laminator, and cure at 140 °C for 15 min. There should be no bubbles in the EVA film in the laminated cured sample, and prepare 3 laminated sample specimens. Cut the flexible backsheet / EVA film layer into specimens with a width of 10 mm ± 0.5 mm every 5 mm in the width direction for the peel force test between EVA and glass. According to the test method of GB / T2790—1995, measure the peel force F between the glass and the film after the aging test on a tensile testing machine at a tensile speed of 100 mm / min ± 10 mm / min, and divide F by the specimen width to obtain the peel strength. The test results of each example and comparative example are shown in Table 1.

[0081] (2) Photoaging Performance Test

[0082] Take two pieces of EVA photovoltaic films prepared in each of the above-mentioned examples and comparative examples, one piece of ultra-white embossed tempered glass with a thickness of 3.2 mm, and one piece of flexible backsheet. Stack them in the order of glass / EVA film (two pieces) / flexible backsheet, put them into a vacuum laminator, and cure at 140 °C for 15 min. There should be no bubbles in the EVA film in the laminated cured sample to obtain a laminated part. Then, place the laminated part with the glass side facing the light source in a xenon lamp aging chamber for a photoaging experiment. The experimental conditions are: 0.6 W / m 2 / nm@340 nm, and the aging duration is 800 h. Then, measure the yellowness index YI of the aged laminated part according to ASTM E313-2010. Measure at least 3 points for each specimen, and take the average value of the measured points as the yellowness index YI of the specimen. Record the difference between the yellowness index YI after aging and the yellowness index YI before aging, that is, the yellowing index ΔYI. The test results of each example and comparative example are shown in Table 1.

[0083] Table 1 Test Results of Peel Strength and Photoaging

[0084]

[0085]

[0086] As can be seen from the results in Table 1, the EVA photovoltaic film modified with the anti-aging agent of the EVA photovoltaic film prepared by the present invention has a comparable peel strength with glass before the aging test compared with the EVA photovoltaic film directly added with the hindered amine light stabilizer. However, after aging, the EVA photovoltaic film prepared by the present invention has a higher peel strength and a lower yellowing index, which indicates that the anti-aging agent of the EVA photovoltaic film provided by the present invention has a better anti-aging effect than directly adding the anti-aging agent.

[0087] In summary, the present invention prepares a novel anti-aging agent for EVA photovoltaic film by grafting a hindered amine light stabilizer onto the EVA main chain through a reactive extrusion process; this process is convenient to operate and can be continuously produced; and applying this anti-aging agent for EVA photovoltaic film to the preparation of EVA photovoltaic film can significantly improve the anti-aging performance of the EVA photovoltaic film.

[0088] The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those familiar with this technology to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing an EVA photovoltaic film anti-aging additive, characterized in that: The method comprises the following steps: uniformly mixing a peroxide initiator, a reactive hindered amine light stabilizer and an EVA resin by mechanical mixing; then placing the mixture in a twin-screw extruder for reaction, and obtaining the EVA photovoltaic adhesive film anti-aging additive by extrusion; wherein the reactive hindered amine light stabilizer is a reactive hindered amine light stabilizer containing a carbon-carbon double bond.

2. The preparation method according to claim 1, characterized in that: The peroxide initiator is selected from at least one of tert-butyl peroxycarbonate-2-ethylhexyl ester, tert-amyl peroxy (2-ethylhexyl) carbonate, diisopropylbenzene peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane or 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane.

3. The preparation method according to claim 1, characterized in that: The reactive hindered amine light stabilizer is selected from 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate and / or 2,2,6,6-tetramethyl-4-piperidinyl methacrylate.

4. The preparation method according to claim 1, characterized in that: The added amount of the peroxide initiator is 0.1% to 3.0% of the mass of the EVA resin, preferably 0.5% to 3.0%.

5. The preparation method according to claim 1, characterized in that: The added amount of the reactive hindered amine light stabilizer is 1.0% to 10% of the mass of the EVA resin.

6. The preparation method according to claim 1, characterized in that: The temperature of the twin-screw extruder is 80-220° C., and the main screw speed is 50-500 rpm.

7. An anti-aging additive for EVA photovoltaic adhesive film prepared according to the preparation method according to any one of claims 1 to 6.

8. An EVA photovoltaic film, characterized in that: The invention comprises EVA resin and EVA photovoltaic film anti-aging aid, wherein the EVA photovoltaic film anti-aging aid is the EVA photovoltaic film anti-aging aid as claimed in claim 7, and the addition amount of the EVA photovoltaic film anti-aging aid is 1% to 25% of the mass of the EVA resin.

9. The EVA photovoltaic adhesive film according to claim 8, characterized in that: It includes EVA resin, EVA photovoltaic adhesive film anti-aging aid, cross-linking agent, auxiliary cross-linking agent and silane coupling agent; wherein, the added amount of the EVA photovoltaic adhesive film anti-aging aid is 1.0% to 20% of the mass of the EVA resin, the added amount of the cross-linking agent is 1.0% to 3.0% of the total mass of the EVA resin and the EVA photovoltaic adhesive film anti-aging aid, the added amount of the auxiliary cross-linking agent is 0.5% to 2.0% of the total mass of the EVA resin and the EVA photovoltaic adhesive film anti-aging aid, and the added amount of the silane coupling agent is 0.05 to 1.0% of the total mass of the EVA resin and the EVA photovoltaic adhesive film anti-aging aid.

10. The EVA photovoltaic adhesive film according to claim 9, characterized in that: The crosslinking agent is selected from at least one of tert-butyl peroxycarbonate-2-ethylhexyl ester, tert-amyl peroxy (2-ethylhexyl) carbonate, dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane or 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane; The auxiliary cross-linking agent is selected from at least one of triallyl isocyanurate, trimethylolpropane trimethacrylate, hexanediol dimethacrylate, butanediol dimethacrylate or ethylene glycol dimethacrylate; The silane coupling agent is selected from at least one of γ-(methacryloyloxy)propyltrimethoxysilane, 3-(trimethoxysilyl)propyl methacrylate, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyltriethoxysilane or γ-glycidyloxypropyltrimethoxysilane.

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