Blended eva-eaa-pvb encapsulating adhesive film, preparation method and application thereof

Abstract

The present application relates to the technical field of photovoltaic adhesive film, especially to a blended EVA-EAA-PVB encapsulation adhesive film, a preparation method and application thereof. The blended EVA-EAA-PVB encapsulation adhesive film is mainly prepared from EVA resin 40-70 parts by weight, EAA resin 5-40 parts by weight, modified PVB resin 30-90 parts by weight, peroxide crosslinking agent 0.4-1 part by weight, auxiliary crosslinking agent 0.2-0.8 part by weight, light stabilizer 0-0.3 part by weight and antioxidant 0-0.3 part by weight; the modified PVB resin is mainly prepared from PVB resin 20-50 parts by weight, plasticizer 10-40 parts by weight and silane coupling agent 0.1-2 parts by weight; and the content of acrylic acid in the EAA resin is greater than or equal to 6 wt%. The encapsulation adhesive film has high mechanical properties, optical properties, moisture and heat aging resistance and PID resistance, and the preparation method of the encapsulation adhesive film has low processing temperature, low energy consumption and simple process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic adhesive film, in particular to a blended EVA-EAA-PVB encapsulation adhesive film and a preparation method and application thereof. BACKGROUND

[0002] The BIPV component is packaged by upper and lower two layers of tempered glass to encapsulate the crystalline silicon solar cell, and the glass and the crystalline silicon cell are bonded together through the internal thermoplastic adhesive film. At present, the encapsulation of domestic BIPV components mainly uses two kinds of encapsulation materials of EVA and PVB. The EVA adhesive film has the characteristics of strong adhesion, excellent optical performance and simple laminating process, and is very suitable for the encapsulation of battery pieces. However, the anti-ultraviolet ability is weak, and it is easy to turn yellow and black after long-term sun exposure, and the mechanical properties such as tensile strength are poor, so it is mainly used for indoor partition in building curtain wall application. PVB has good mechanical properties, sound insulation, transparency and anti-ultraviolet ability; the content of hydroxyl in the structure is high, so it has good adhesion, but it also leads to poor water resistance of PVB. And the processing conditions are relatively strict, and the piece combination needs high temperature and high pressure, and most of them are produced by autoclave. At the same time, PVB film has high hardness, and when used as an encapsulation adhesive film in photovoltaic components, it often leads to the breakage and damage of the battery pieces.

[0003] The existing PVB and EVA are usually used in a layer-by-layer stacking manner, but the EVA layer still needs a large amount of additives to achieve cross-linking effect, and the strict processing conditions of PVB cannot be avoided. Moreover, EVA is a random copolymer composed of non-polar, crystalline ethylene monomer and strong polar, non-crystalline vinyl acetate monomer, and PVB is a polar crystalline polymer, the differences between the two in morphology, structure and solubility parameter are large, resulting in weak interfacial force, and when subjected to external force, defects in the system are easy to develop into cracks at the interface and cause material damage, so the EVA and PVB system is a very incompatible blending system.

[0004] Therefore, the present application is proposed. SUMMARY

[0005] One object of the present application is to provide a blended EVA-EAA-PVB encapsulation adhesive film to solve the technical problems of strict processing conditions and poor performance of existing EVA and PVB adhesive films in the prior art.

[0006] Another object of the present application is to provide a preparation method of the blended EVA-EAA-PVB encapsulation adhesive film.

[0007] Still another object of the present application is to provide the application of the blended EVA-EAA-PVB encapsulation adhesive film in the preparation of photovoltaic components.

[0008] In order to achieve the above objects of the present application, the following technical solutions are adopted:

[0009] The EVA-EAA-PVB encapsulating adhesive film is prepared from the following components by weight:

[0010] EVA resin 40-70 parts, EAA resin 5-40 parts, modified PVB resin 30-90 parts, peroxide crosslinking agent 0.4-1 part, auxiliary crosslinking agent 0.2-0.8 part, light stabilizer 0-0.3 part, and antioxidant 0-0.3 part;

[0011] The modified PVB resin is prepared from PVB resin 20-50 parts, plasticizer 10-40 parts, and silane coupling agent 0.1-2 parts by weight.

[0012] The EAA resin has an acrylic acid content of ≥6wt%.

[0013] In the specific embodiment of the present application, the EAA resin has an acrylic acid content of 15wt%-20wt%. Further, the EAA resin has a melt index of 10-300 g / 10 min, preferably 10-40 g / 10 min.

[0014] In the specific embodiment of the present application, the EVA resin has a VA content of ≥25wt%. Further, the EVA resin has a VA content of 26wt%-30wt%.

[0015] In the specific embodiment of the present application, the PVB resin has a hydroxyl content of ≥18wt% and an acetyl content of ≥1wt%. Further, the PVB resin has a hydroxyl content of 18wt%-21wt% and an acetyl content of 1wt%-4wt%.

[0016] In the specific embodiment of the present application, the PVB resin has a molecular weight of 60000-100000.

[0017] In the specific embodiment of the present application, the preparation of the modified PVB resin comprises weighing PVB resin, plasticizer, and silane coupling agent in proportion, and melt extrusion granulation.

[0018] In the specific embodiment of the present application, the peroxide crosslinking agent comprises any one or more of dicumyl peroxide, di(tert-butylperoxy isopropyl)benzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, and 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane.

[0019] In the specific embodiment of the present application, the auxiliary crosslinking agent comprises any one or more of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethylene glycol diacrylate, triallyl cyanurate, and triallyl isocyanurate.

[0020] In the detailed description of the application, the light stabilizer includes any one or more of phenyl salicylate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2-(2-hydroxy-5-methylphenyl)benzotriazole and m-phenylenediamine monobenzoate.

[0021] In the detailed description of the application, the antioxidant includes any one or more of tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid octadecyl ester, tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite and 2,6-di-tert-butyl-4-methylphenol.

[0022] In the detailed description of the application, the plasticizer includes at least one of aliphatic diesters of triethylene glycol and aliphatic diesters of tetraethylene glycol. Further, the plasticizer includes any one or more of triethylene glycol diisooctanoate, ethylene glycol di-n-heptanoate, tetraethylene glycol di-n-heptanoate, dibutyl sebacate and di-n-hexyl adipate.

[0023] In the detailed description of the application, the silane coupling agent includes any one or more of 3-glycidyloxypropylmethyldiethoxysilane, 3-glycidyloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-ureidopropyltrialkoxysilane and 3-mercaptopropyltrimethoxysilane.

[0024] The application also provides a preparation method of the blended EVA-EAA-PVB encapsulation adhesive film, which comprises the following steps:

[0025] (a) extruding and granulating the EVA resin and the EAA resin to obtain EVA-EAA;

[0026] (b) extrusion casting the EVA-EAA, the modified PVB resin, the peroxide crosslinking agent, the auxiliary crosslinking agent, the light stabilizer and the antioxidant.

[0027] The application also provides application of the blended EVA-EAA-PVB encapsulation adhesive film in preparation of a photovoltaic module.

[0028] In the detailed description of the application, the laminating method of the photovoltaic module comprises laminating at 150±5℃ for 10-15 min.

[0029] Compared with the prior art, the application has the following beneficial effects:

[0030] (1) The present application introduces EAA into the system, utilizes the structural similarity of EAA and EVA, and the strong interaction between the alcohol hydroxyl in the PVB molecular chain and the acrylic group in the EAA, increases the mutual entanglement between the molecular chains, improves the compatibility, mechanical and optical properties of EVA and PVB, and avoids the problems of poor light transmission and low tensile strength caused by poor compatibility;

[0031] (2) The present application introduces a crosslinking agent into the system, so that part of the EVA, EAA and PVB react in situ, reduces the generation of C=C conjugated double bond system during EVA crosslinking, thereby reducing the absorption of ultraviolet light and reducing the risk of yellowing of the film; at the same time, the dense crosslinked structure formed reduces the possibility of water vapor entering and reduces the PID decay rate;

[0032] (3) The encapsulation film of the present application has high mechanical properties, optical properties, moisture and heat aging resistance and PID resistance, and the preparation method of the encapsulation film has low processing temperature, reduces energy consumption, and the process is simple. DETAILED DESCRIPTION

[0033] The technical solutions of the present application will be described below in conjunction with specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. If the specific conditions are not specified in the examples, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0034] The blended EVA-EAA-PVB encapsulation film is mainly prepared from the following components by weight fraction:

[0035] EVA resin 40-70 parts, EAA resin 5-40 parts, modified PVB resin 30-90 parts, peroxide crosslinking agent 0.4-1 part, crosslinking aid 0.2-0.8 parts, light stabilizer 0-0.3 parts and antioxidant 0-0.3 parts;

[0036] The modified PVB resin is mainly prepared from PVB resin 20-50 parts, plasticizer 10-40 parts and silane coupling agent 0.1-2 parts by weight fraction;

[0037] The EAA resin has an acrylic acid content of 6wt% or more.

[0038] The amount of each component used to prepare the blended EVA-EAA-PVB encapsulating adhesive film can be exemplarily as follows in different embodiments, in parts by weight:

[0039] The amount of EVA resin can be 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, etc.

[0040] The amount of EAA resin can be 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, etc.

[0041] The amount of modified PVB resin can be 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, etc.

[0042] The amount of peroxide crosslinking agent can be 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, etc.

[0043] The amount of crosslinking aid can be 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, etc.

[0044] The amount of light stabilizer can be 0 parts, 0.1 parts, 0.2 parts, 0.3 parts, etc.

[0045] The amount of antioxidant can be 0 parts, 0.1 parts, 0.2 parts, 0.3 parts, etc.

[0046] In the modified PVB resin, the amount of PVB resin can exemplarily be 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, etc., the amount of plasticizer can exemplarily be 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, etc., and the amount of silane coupling agent can exemplarily be 0.1 parts, 0.2 parts, 0.5 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, etc., in different embodiments.

[0047] In the EAA resin, the content of acrylic acid (AA) can be ≥6 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, etc., in different embodiments.

[0048] The present application introduces ethylene-acrylic acid copolymer EAA into the encapsulating adhesive film system. Since EAA has a similar structure to EVA, and the acrylic acid groups in EAA can have a strong interaction with the alcohol hydroxyl groups in the PVB molecular chain, the intermolecular entanglement is increased, the compatibility and mechanical and optical properties are improved, and the problems of poor light transmission and low tensile strength caused by poor compatibility are avoided.

[0049] In addition, due to the introduction of EAA, EVA and PVB are closely combined, so that the blended packaging adhesive film is more compact, and a higher crosslinking degree can be achieved with less amount of additives. At the same time, due to the lower processing temperature and pressure of EAA and EVA, the processing temperature of PVB is moved to a lower temperature and lower pressure during the introduction process, so that the laminating process does not need to use the harsh autoclave process of PVB, and a good crosslinking effect can be achieved at a lower temperature for a shorter time, thereby simplifying the process and reducing energy consumption.

[0050] In the packaging adhesive film system of the present application, a crosslinking agent is added, and part of EVA, EAA and PVB are in-situ reacted, so that the generation of C=C conjugated double bond system during the crosslinking of EVA is reduced, thereby reducing the absorption of ultraviolet light and reducing the risk of yellowing of the adhesive film. At the same time, the compact crosslinking structure reduces the possibility of water vapor entering and reduces the PID decay rate.

[0051] The tensile strength of the blended EVA-EAA-PVB packaging adhesive film of the present application is >25MPa, the elongation at break is >500%, and the tear strength is >40N, which fully meets the requirements of the tensile strength being greater than 23MPa, the elongation at break being greater than 230%, and the tear strength being greater than 30N in JG / T 449-2014 line standard "Polyvinyl Butyral (PVB) Adhesive Film for Building Photovoltaic Modules". And the 192h anti-PID decay rate can be less than 2%.

[0052] In the specific embodiment of the present application, the silane coupling agent contains at least one of epoxy group, amino group, urea group and mercapto group.

[0053] Since the carbon-oxygen double bond and carbon-oxygen single bond in vinyl acetate are polar bonds, they have good hydrophilicity, so the water resistance of EVA adhesive film in the module is poor, and the water vapor transmission rate is high; and PVB contains a large number of hydroxyl groups, which are very easy to be hydrophilic with water molecules; therefore, the introduction of EAA solves the blending compatibility and improves the mechanical properties, but the improvement of water vapor barrier property still cannot guarantee that the blended packaging adhesive film has good effect in the weathering and humid aging test. Therefore, the PVB resin is pre-grafted with silane in the present application, and the epoxy group, amino group, urea group or mercapto group in the silane coupling agent reacts with the broken hydroxyl group on the PVB at high temperature, the grafted PVB-SiOR can react with another hydroxyl group on the PVB, thereby forming a crosslinking structure, reducing the hydroxyl group exposed on the outside of the structure, and improving the weather resistance of PVB. At the same time, the silane coupling agent can be between inorganic glass and organic polymer, and a combined layer of polymer-silane coupling agent-glass can be formed, so it will not affect the peeling strength with glass after film formation.

[0054] And, in order to further ensure the compatibility between EVA, EAA and PVB, a plasticizer is added in PVB, which is inserted into the middle of PVB resin molecular chain, increases the distance between molecules, weakens the intermolecular force, reduces the melt viscosity, increases the flexibility of molecular chain, and makes the PVB molecules more easily combined with EVA resin and EAA resin after the opening of molecular chain.

[0055] In the specific embodiment of the present application, the blended EVA-EAA-PVB encapsulating adhesive film is prepared from the following components by weight:

[0056] EVA resin 40-65 parts, EAA resin 5-20 parts, modified PVB resin 50-65 parts, peroxide crosslinking agent 0.4-0.6 parts, auxiliary crosslinking agent 0.3-0.5 parts, light stabilizer 0.05-0.2 parts and antioxidant 0.05-0.2 parts.

[0057] In the specific embodiment of the present application, the modified PVB resin is prepared from PVB resin 30-40 parts, plasticizer 15-25 parts and silane coupling agent 0.1-0.5 parts by weight.

[0058] In the specific embodiment of the present application, the EAA resin has an acrylic acid content of 15wt%-20wt%. Further, the EAA resin has a melt index (190℃, 2.16kg) of 10-300g / 10min, preferably 10-40g / 10min.

[0059] As in different embodiments, the EAA resin can have an acrylic acid content of 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt% and the like; and the EAA resin can have a melt index of 10g / 10min, 20g / 10min, 30g / 10min, 40g / 10min, 50g / 10min, 100g / 10min, 150g / 10min, 200g / 10min, 250g / 10min, 300g / 10min and the like.

[0060] In the specific embodiment of the present application, the EVA resin has a VA content of ≥25wt%. Further, the EVA resin has a VA content of 26wt%-30wt%.

[0061] As in different embodiments, the EVA resin can have a VA content of 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt% and the like.

[0062] In the specific embodiments of the present application, the hydroxyl content in the PVB resin is ≥18wt%, and the acetyl content is ≥1wt%. Further, the hydroxyl content in the PVB resin is 18wt% to 21wt%, and the acetyl content is 1wt% to 4wt%.

[0063] As in different embodiments, the hydroxyl content in the PVB resin can be exemplarily 18wt%, 18.5wt%, 19wt%, 19.5wt%, 20wt%, 20.5wt%, 21wt%, etc.; and the acetyl content can be exemplarily 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%.

[0064] In the specific embodiments of the present application, the number average molecular weight of the PVB resin is 60000 to 100000.

[0065] As in different embodiments, the number average molecular weight of the PVB resin can be exemplarily 60000, 70000, 80000, 90000, 100000, etc.

[0066] By using the EVA resin, the EAA resin and the PVB resin meeting the above conditions, the high modulus of the adhesive film and the matching of the casting process are further considered.

[0067] In the specific embodiments of the present application, the amount of the EAA resin accounts for 5% to 10% of the total mass of the EVA resin, the EAA resin and the PVB resin.

[0068] As in different embodiments, the amount of the EAA resin can account for 5%, 6%, 7%, 8%, 9%, 10% of the total mass of the EVA resin, the EAA resin and the PVB resin.

[0069] In the specific embodiments of the present application, the preparation of the modified PVB resin comprises: weighing the PVB resin, the plasticizer and the silane coupling agent in proportion, and performing extrusion granulation.

[0070] In the specific embodiments of the present application, in the preparation of the modified PVB resin, the extrusion granulation can be performed by using a double-screw extruder. Further, the temperature of the extrusion granulation is 130 to 170℃.

[0071] In the specific embodiments of the present application, the peroxide crosslinking agent comprises any one or more of dicumyl peroxide, di(tert-butylperoxy isopropyl)benzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane and 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane.

[0072] In the detailed description of the application, the co-crosslinking agent includes any one or more of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethylene glycol diacrylate, triallyl cyanurate and triallyl isocyanurate.

[0073] In the detailed description of the application, the light stabilizer includes any one or more of phenyl salicylate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2-(2-hydroxy-5-methylphenyl)benzotriazole and m-phenylenediamine monobenzoate.

[0074] In the detailed description of the application, the antioxidant includes any one or more of pentaerythrityl tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythrityl diphosphite and 2,6-di-tert-butyl-4-methylphenol.

[0075] In the detailed description of the application, the plasticizer includes at least one of aliphatic diesters of triethylene glycol and aliphatic diesters of tetraethylene glycol. Further, the plasticizer includes at least one of aliphatic diesters of triethylene glycol and aliphatic diesters of tetraethylene glycol. Further, the plasticizer includes any one or more of triethylene glycol diisooctanoate, ethylene glycol di-n-heptanoate, tetraethylene glycol di-n-heptanoate, dibutyl sebacate and di-n-hexyl adipate.

[0076] In the detailed description of the application, the silane coupling agent includes any one or more of 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-ureidopropyltrialkoxysilane and 3-mercaptopropyltrimethoxysilane.

[0077] The application also provides a preparation method of the blended EVA-EAA-PVB packaging adhesive film, including the following steps:

[0078] (a) EVA resin and EAA resin are extruded and granulated to obtain EVA-EAA;

[0079] (b) EVA-EAA, modified PVB resin, peroxide crosslinking agent, co-crosslinking agent, light stabilizer and antioxidant are extruded and cast.

[0080] In order to prevent the strong interaction between the acrylic groups in the EAA and the alcohol hydroxyl groups in the PVB molecular chain from preferentially combining to form a PVB-g-EAA graft material with medium-high polarity, resulting in the low-polarity EVA still being unable to be compatible with the medium-high-polarity PVB-g-EAA, the present application first grafts the EAA and the EVA with similar structures in a molten state to form an EVA-g-EAA material with medium-high polarity, and then blends the EVA-g-EAA material with the high-polarity PVB resin, so as to form a uniform, transparent and three-component resin with certain tensile strength.

[0081] In the specific embodiment of the present application, in step (a), the extrusion granulation can be performed by using a double-screw extruder. Further, in step (a), the temperature of the extrusion granulation is 100-150°C.

[0082] In the specific embodiment of the present application, in step (b), the extrusion granulation can be performed by using a double-screw extrusion casting machine. Further, in step (b), the temperature of the extrusion casting is 130-160°C.

[0083] In actual operation, after the extrusion casting, the conventional operations such as rolling, edge cutting, winding and packaging can be further included.

[0084] The present application also provides the use of any one of the above-mentioned blended EVA-EAA-PVB encapsulating adhesive films in the preparation of photovoltaic modules.

[0085] In the specific embodiment of the present application, the lamination method of the photovoltaic module comprises: lamination treatment at 150±5°C for 10-15 min.

[0086] The encapsulating adhesive film system of the present application does not need to use the strict autoclave process of PVB, and can achieve a good crosslinking effect in a relatively low temperature for a relatively short time, thereby simplifying the process and reducing the energy consumption.

[0087] A photovoltaic module comprises any one of the above-mentioned blended EVA-EAA-PVB encapsulating adhesive films.

[0088] Examples 1-6

[0089] Examples 1-6 provide blended EVA-EAA-PVB encapsulating adhesive films and the preparation methods thereof, wherein the raw material compositions of the blended EVA-EAA-PVB encapsulating adhesive films are shown in Table 1, and the preparation method comprises the following steps:

[0090] (1) EVA resin and EAA resin are weighed according to the proportion, extruded and granulated on a double-screw extruder at 140°C, and after drying the moisture, EVA / EAA is obtained;

[0091] (2) PVB resin, plasticizer and silane coupling agent were weighed proportionally, and then extruded and granulated at 150°C in a double screw extruder. After drying the moisture, the modified PVB resin was obtained and ready for use;

[0092] (3) Crosslinking agent, co-crosslinking agent, light stabilizer and antioxidant were added proportionally in EVA / EAA and modified PVB resin obtained in steps (1) and (2), and then dried in a 55°C air-drying oven in a sealed state. The film with a thickness of 450-500 g / m2was obtained by casting on an extruder at 100°C. 2

[0093] Table 1 Raw material composition information of packaging adhesive film of different examples (weight parts)

[0094] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 EVA resin 65 60 50 55 50 40 EAA resin 5 10 20 5 10 20 PVB resin 30 30 30 40 40 40 Plasticizer 20 20 20 20 20 20 Silane coupling agent 0.2 0.2 0.2 0.2 0.2 0.2 Crosslinking agent 0.5 0.5 0.5 0.5 0.5 0.5 Co-crosslinking agent 0.4 0.4 0.4 0.4 0.4 0.4 Light stabilizer 0.1 0.1 0.1 0.1 0.1 0.1 Antioxidant 0.1 0.1 0.1 0.1 0.1 0.1

[0095] The VA content in the EVA resin is 28wt%, and the melt index is 25 g / 10 min;

[0096] The hydroxyl content in the PVB resin is 18wt%-21wt%, the acetyl content is 1wt%-4wt%, and the number average molecular weight is 60000-100000;

[0097] The AA content in the EAA resin is 15wt%, and the melt index is 30 g / 10 min;

[0098] The plasticizer is triethylene glycol diisooctylate;

[0099] The silane coupling agent is N-2-(aminoethyl)-3-aminopropyl methyl dimethoxy silane;

[0100] The crosslinking agent is 2,5-dimethyl-2,5-bis(tert-butyl peroxy) hexane;

[0101] The co-crosslinking agent is trimethylolpropane triacrylate;

[0102] The light stabilizer is 2-(2-hydroxy-5-methylphenyl) benzotriazole;

[0103] The antioxidant is tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester alcohol.

[0104] Comparative Example 1

[0105] Comparative Example 1 provides an EVA pure film packaging adhesive film and a preparation method thereof, including the following steps:

[0106] ​EVA resin 100 parts, crosslinking agent 1 part, co-crosslinking agent 0.8 part, silane coupling agent 0.5 part, light stabilizer 0.1 part and antioxidant 0.1 part by weight were weighed and dried in a 55°C air drying oven, and a 450-500 g / m 2 film was cast on an extruder at 100°C.

[0107] The resins and crosslinking agent, co-crosslinking agent, silane coupling agent, light stabilizer and antioxidant involved in the raw materials are the same as those used in Example 1.

[0108] Comparative Example 2

[0109] Comparative Example 2 refers to the EVA pure film packaging adhesive film in Comparative Example 1, except that the amount of additives is different. The preparation method of Comparative Example 2 comprises:

[0110] EVA resin 100 parts, crosslinking agent 0.5 part, co-crosslinking agent 0.4 part, silane coupling agent 0.2 part, light stabilizer 0.1 part and antioxidant 0.1 part by weight were weighed and dried in a 55°C air drying oven, and a 450-500 g / m 2 film was cast on an extruder at 100°C.

[0111] Comparative Example 3

[0112] Comparative Example 3 provides a blended EVA-PVB packaging adhesive film and a preparation method thereof, comprising the following steps:

[0113] (1) EVA resin 70 parts and PVB resin 30 parts by weight were weighed and extruded on a twin-screw extruder at 140°C, and after drying, they were ready for use;

[0114] (2) To the particles obtained in step (1), 20 parts of plasticizer, 0.5 parts of crosslinking agent, 0.4 parts of co-crosslinking agent, 0.2 parts of silane coupling agent, 0.1 parts of light stabilizer and 0.1 parts of antioxidant were added, and dried in a 55°C air drying oven, and a 450-500 g / m 2 film was cast on an extruder at 100°C.

[0115] The resins and plasticizer, crosslinking agent, co-crosslinking agent, silane coupling agent, light stabilizer and antioxidant involved in the raw materials are the same as those used in Example 1.

[0116] Comparative Example 4

[0117] Comparative Example 4 provides a blended EVA-EAA-PVB packaging adhesive film and a preparation method thereof, comprising the following steps:

[0118] (1) EVA resin 60 parts, EAA resin 10 parts, PVB resin 30 parts were weighed by weight fraction respectively, and extruded and granulated at 140°C on a twin-screw extruder, and dried after drying the moisture, and then used;

[0119] (2) To the particles obtained in step (1), 20 parts of plasticizer, 0.5 parts of crosslinking agent, 0.4 parts of co-crosslinking agent, 0.2 parts of silane coupling agent, 0.1 parts of light stabilizer and 0.1 parts of antioxidant were added, and dried in a 55°C air drying oven, and then cast into a 450-500 g / m 2 film on an extruder at 100°C.

[0120] Among them, the resins and plasticizers, crosslinking agents, co-crosslinking agents, silane coupling agents, light stabilizers and antioxidants involved in the raw materials are all the same as those used in Example 1.

[0121] Comparative Example 5

[0122] Comparative Example 5 refers to the blended EVA-EAA-PVB packaging adhesive film of Example 2, with the difference being the preparation method. The preparation method of Comparative Example 3 includes:

[0123] (1) EVA resin 60 parts, EAA resin 10 parts were weighed by weight fraction respectively, and extruded and granulated at 140°C on a twin-screw extruder, and dried after drying the moisture, and then used;

[0124] (2) PVB resin 100 parts, plasticizer 20 parts were weighed by weight fraction respectively, and extruded and granulated at 140°C on a twin-screw extruder, and dried after drying the moisture, and then used;

[0125] (3) After drying the particles of step (1) and step (2), the particles were weighed so that the EVA, EAA, PVB particles in the mixed particles were 60 parts, 10 parts, and 30 parts respectively. 0.5 parts of crosslinking agent, 0.4 parts of co-crosslinking agent, 0.2 parts of silane coupling agent, 0.1 parts of light stabilizer and 0.1 parts of antioxidant were added in the mixed particles, and dried in a 55°C air drying oven, and then cast into a 450-500 g / m 2 film on an extruder at 100°C.

[0126] Experimental Example 1

[0127] In order to compare and illustrate the differences between the packaging adhesive films prepared by different examples and comparative examples, the packaging adhesive films prepared by different examples and comparative examples were tested as follows, and the test results are shown in Table 2.

[0128] 1. Crosslinking degree test: take 100mm*100mm sample into laminator 150℃, 10min later take out, after cooling, cut into 3mm*3mm small pieces, take 0.2000g±0.0050g (record W2); put small pieces into 120 mesh stainless steel bag with known weight (record W1), put sample into boiling xylene solution, keep boiling for 5h, extract. After extraction, put into 140℃ vacuum drying oven for 3h, cool and take out, weigh (record W3).

[0129] Crosslinking degree calculation formula: (W3-W1) / (W2-W1)*100%

[0130] 2. Light transmittance test: take 100mm*100mm sample into laminator 150℃, 10min later take out, after cooling, cut into 30mm*50mm small pieces, put into UV-visible spectrophotometer to test light transmittance in 380-1100nm range.

[0131] 3. Tensile strength and elongation at break test: laminate at 150℃, 10min, cool to room temperature, sample shape and size are cut from large sample according to the provisions of type 5 test in GB / T 1040.3-2006, 5 samples are prepared for each group. Record sample thickness d with micrometer, perform tensile test on tensile testing machine at 100±10mm / min, record tensile strength and elongation at break value.

[0132] 4. Tear strength: laminate at 150℃, 10min, cool to room temperature, sample shape and size are cut from large sample according to the provisions of right angle type sample in GB / T 529-2008, 5 samples are prepared for each group, perform tear strength test on tensile testing machine at 100±10mm / min, record maximum value F. Tear strength T S = F / d.

[0133] 5. DH-peeling strength test: take adhesive film with size of 200mm*100mm, prepare sample according to the order of glass-adhesive film-back plate, laminate at 150℃, 10min, after cooling, observe sample appearance without defects, crosslinking degree is consistent, put into high temperature and humidity aging oven with temperature of 85±5℃ and humidity of 85±5% for 1000h, take out and test peeling strength.

[0134] 6. DH-△Y test: Take the size of 70 mm*70 mm adhesive film, prepare the sample in the order of glass-adhesive film-back plate, laminate at 150℃ for 10 min, observe the appearance of the prepared sample after cooling, no defects, uniform crosslinking degree, test the yellowness index, record Y1. Put into the temperature 85±5℃, humidity 85±5% high temperature and high humidity aging oven for 1000h, take out and test the yellowness index, record Y2. DH-△Y=Y2-Y1.

[0135] 7. Power attenuation test: 166mm PERC cell is connected in series according to 2*10 half pieces, and is laminated into a photovoltaic module with no defects in appearance according to the order of glass-adhesive film-cell-adhesive film-glass at 150℃ for 10 min. According to the enterprise standard module, the sample power is tested (recorded as P1). Put into the temperature 85±5℃, humidity 85±5% high temperature and high humidity aging oven, connect the PID power supply-1500V, make the module power on, test the sample power after 192h (recorded as P2). Power attenuation rate=(P1-P2) / P1*100%.

[0136] Table 2 Performance test results of encapsulation adhesive film of different embodiments

[0137]

[0138]

[0139] Note: Wherein "--" means not tested

[0140] From the above test results, it can be seen that the pure film of Comparative Example 1 and the pure film of Comparative Example 2 are compared, the amount of additives in the formula is reduced by half, but the crosslinking degree is greatly reduced, and the tensile strength is not high, which cannot meet the requirement of PVB building photovoltaic module tensile strength greater than 23MPa.

[0141] The tensile strength of the encapsulation adhesive film of Comparative Example 3 is only 5.77MPa, and stress whitening phenomenon occurs in the tensile experiment, which is due to the incompatibility of EVA and PVB, the formation of cavities between polymer molecules, and the generation of a large number of crazes under stress. The refractive index of the craze area is reduced, the haze is increased, and the light transmittance is decreased.

[0142] The encapsulation adhesive film of Comparative Example 4 simply blends each component, EAA will preferentially combine with PVB with higher polarity, resulting in a large difference in polarity between EVA and PVB-EAA, and the problem of poor compatibility is not solved.

[0143] The difference between Comparative Example 5 and Example 2 is whether the PVB is modified in advance with silane coupling agent. Comparative Example 5 is not modified in advance. The difference in tensile strength, elongation at break and tear strength is not large. The main difference is in the peel strength and power attenuation rate after aging test. The peel strength after DH-1000h is only 89.60 N / cm. The main reason is that the PVB contains a large amount of hydroxyl groups, which has good hydrophilicity, so the weather resistance is poor, and the PID power attenuation resistance is poor.

[0144] The encapsulant films of Examples 1-6 have the same amount of additives as Comparative Examples 3 and 2. When the amount of EAA is 5% of the total mass of EVA, EAA and PVB, the tensile strength is greatly improved to 25.99 MPa, and the tear strength is 45.97 MPa, which fully meets the requirements of the building photovoltaic module standard for pure PVB film. When the amount of EAA is 10% of the total mass of EVA, EAA and PVB, the tensile strength and tear strength are slightly lower than when the amount of EAA is 5%, but they still meet the standards of tensile strength > 23 MPa and tear strength > 36 N. The addition of EAA does not reduce the light transmittance of the film. This further shows that the EAA introduced in the application is compatible with EVA and has good reactivity with PVB, increasing the mutual entanglement between molecular chains, improving compatibility and mechanical and optical properties, and avoiding problems such as poor light transmittance and low tensile strength caused by poor compatibility. However, when the amount of EAA continues to increase, the performance will be greatly reduced, especially in terms of tensile strength. This is because EAA itself has low strength and modulus, so increasing the content of EAA will increase the rigidity of the film and greatly reduce the tensile strength.

[0145] At the same time, Examples 1-6 were tested for peel strength, yellowing and power attenuation at 85℃±5℃ and 85%±5% relative humidity for 1000h. Examples 3 and 6 delaminated from the glass after 1000h due to the excessive amount of EAA, which caused the mechanical properties of the film to deteriorate. Examples 1, 2, 4 and 5 still had a peel strength greater than 100 N / cm, a yellowing less than 2% and a power attenuation less than 2% after 1000h. The reason may be that the grafting of silane coupling agent with PVB reduces the exposure of hydroxyl groups in the PVB molecule, reduces hydrophilicity and improves weather resistance. In addition, the introduction of EAA increases the interaction force between the polar segments of EAA, EVA and PVB, increases the entanglement between molecular chains, makes the encapsulant film more dense, reduces the entry of water vapor and reduces the PID attenuation rate.

[0146] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. Blended EVA-EAA-PVB encapsulation adhesive film, characterized in that, The following components are prepared according to weight parts: The EVA resin 40~70 parts, the EAA resin 5~40 parts, the modified PVB resin 30~90 parts, the peroxide crosslinking agent 0.4~1 part, the auxiliary crosslinking agent 0.2~0.8 part, the light stabilizer 0~0.3 part and the antioxidant 0~0.3 part; The modified PVB resin is prepared according to weight parts of PVB resin 20~50 parts, plasticizer 10~40 parts and silane coupling agent 0.1~2 parts; The preparation of the modified PVB resin comprises: weighing PVB resin, plasticizer and silane coupling agent in proportion, and extruding and granulating; The EAA resin has an acrylic acid content ≥6wt%; The EAA resin accounts for 5%~10% of the total mass of the EVA resin, the EAA resin and the PVB resin; The preparation method of the blended EVA-EAA-PVB packaging adhesive film comprises the following steps: (a) extruding and granulating the EVA resin and the EAA resin to obtain EVA-EAA; (b) extruding and casting the EVA-EAA, the modified PVB resin, the peroxide crosslinking agent, the auxiliary crosslinking agent, the light stabilizer and the antioxidant.

2. The blended EVA-EAA-PVB encapsulating adhesive film according to claim 1, wherein, The EAA resin has an acrylic acid content of 15wt%~20wt%; The EAA resin has a melt index of 10~300g / 10min.

3. The blended EVA-EAA-PVB encapsulating adhesive film according to claim 1, wherein, The EVA resin has a VA content ≥25wt%; And / or, the PVB resin has a hydroxyl content ≥18wt% and an acetyl content ≥1wt%.

4. The blended EVA-EAA-PVB encapsulating adhesive film according to claim 3, wherein, The EVA resin has a VA content of 26wt%~30wt%; And / or, the PVB resin has a hydroxyl content of 18wt%~21wt% and an acetyl content of 1wt%~4wt%; The PVB resin has a molecular weight of 60000~100000.

5. The blended EVA-EAA-PVB encapsulating adhesive film according to claim 1, wherein, The temperature of the extruding and granulating is 130~170℃.

6. The blended EVA-EAA-PVB encapsulating adhesive film according to claim 1, wherein, The silane coupling agent contains at least one of epoxy group, amino group, urea group and mercapto group.

7. The method for preparing the blended EVA-EAA-PVB encapsulating film according to any one of claims 1 to 6, characterized in that, The preparation method comprises the following steps: (a) extruding and granulating the EVA resin and the EAA resin to obtain EVA-EAA; (b) extruding and casting the EVA-EAA, the modified PVB resin, the peroxide crosslinking agent, the auxiliary crosslinking agent, the light stabilizer and the antioxidant.

8. The preparation method according to claim 7, characterized in that, In step (a), the temperature of the extruding and granulating is 100~150℃; In step (b), the temperature of the extruding and casting is 130~160℃.

9. The use of the blended EVA-EAA-PVB packaging adhesive film according to any one of claims 1~6 in the preparation of photovoltaic modules.

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