Co-extruded photovoltaic adhesive film composition, co-extruded adhesive film and preparation method and application thereof

Abstract

The invention relates to a co-extrusion photovoltaic adhesive film composition, a co-extrusion adhesive film and a preparation method and application thereof in the field of solar cell module packaging. The co-extrusion photovoltaic adhesive film composition comprises a first adhesive film layer component and a second adhesive film layer component, the first adhesive film layer comprises the following components: polyvinyl butyral and copolymer microspheres; the second adhesive film layer comprises a polyolefin polymer, a cross-linking agent and an assistant cross-linking agent; according to the co-extrusion adhesive film disclosed by the invention, through multi-layer combination of PVB and POE, the defect of high yellow index of POE is made up, the defect of PVB adhesive film in water vapor transmittance is avoided, and the mechanical properties such as peel strength of the adhesive film are also greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of solar cell assembly packaging, and more particularly to a co-extruded photovoltaic adhesive film composition, a co-extruded adhesive film, and a preparation method and application thereof. Background Art

[0002] At present, thermoplastic polyolefin elastomer film (POE film) is gradually replacing ethylene-vinyl acetate copolymer film (EVA film) as the main photovoltaic encapsulation film due to its excellent water barrier and better anti-PID performance. However, the existing POE film requires a higher lamination temperature and a longer lamination time, and its light transmittance is lower than that of EVA film. The cost of POE particles is higher than that of EVA particles, which increases the energy consumption and cost of photovoltaic module production and reduces production efficiency and photovoltaic power generation efficiency. Due to the saturated structure of the POE molecular chain, it is a non-polar molecule, and to a certain extent, the peel strength and adhesion to polar glass and polar backplane are not high, which affects the stability of the module.

[0003] On the other hand, building-integrated photovoltaics (BIPV) is a new concept of solar power generation. Photovoltaic products are integrated into buildings. They are not only power generation devices but also part of the building's external structure. This can effectively reduce costs while also taking into account aesthetics. The BIPV market is in its infancy. my country's annual new and renovated building area can reach 4 billion square meters, and the market potential is huge. In BIPV projects, since photovoltaic modules are directly integrated into the building itself and become part of the building, higher requirements are placed on the modules' rain and lightning protection performance, and more stringent requirements are placed on photovoltaic films, such as low water vapor permeability and low water absorption, which can better ensure the stable power output of photovoltaic modules. BIPV photovoltaic films also have higher requirements for yellowing resistance, high light transmittance, low haze, high mechanical strength and weather resistance. In this regard, both PVB and POE films can meet the needs.

[0004] Combining the characteristics of the two films, the preparation of co-extruded films can give full play to the advantages of the two films and try to avoid or reduce the impact of the disadvantages of the two films. In the preparation process of co-extruded films, due to the different molecular structures of PVB and POE, the polar and non-polar molecules are not compatible, and the co-extruded films are prone to stratification, which affects the mechanical properties. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention proposes a co-extruded photovoltaic adhesive film composition, and specifically relates to a co-extruded photovoltaic adhesive film composition, a co-extruded adhesive film, and a preparation method and application thereof.

[0006] The present invention mainly uses thermoplastic polyolefin elastomer and polyvinyl butyral thermoplastic elastomer as the matrix, and uses a mixing device such as a stirrer to complete the blending of the polymer and the additives as a pretreatment, and mixes with other functional additives to improve the performance, especially to improve the fluidity of PVB particles, reduce the water vapor transmission rate of the adhesive film, and at the same time can also meet good peel strength.

[0007] The present invention provides a multi-layer co-extruded adhesive film composition, comprising components such as thermoplastic polyolefin elastomer (POE), polyvinyl butyral (PVB), copolymer microspheres, etc., and can be made into a multi-layer co-extruded adhesive film. The present invention innovatively introduces copolymer microspheres with strong adsorption force, improves the fluidity of polyvinyl butyral powder, and solves the phenomenon of bridging of polyvinyl butyral at the feed inlet. Using polyvinyl butyral as the surface layer, it has higher adhesive film / glass and adhesive film / backplane peel strength, reduces the usage amount of thermoplastic polyolefin elastomer raw materials and crosslinking additives, and reduces the precipitation of additives. The present invention can be applied to double-glass modules or building-integrated photovoltaic cell modules, etc.

[0008] One of the purposes of the present invention is to provide a co-extruded photovoltaic adhesive film composition, comprising a first adhesive film layer component and a second adhesive film layer component;

[0009] The first adhesive film layer component comprises polyvinyl butyral and copolymer microspheres;

[0010] The second adhesive film layer component comprises polyolefin polymer, crosslinking agent, and co-crosslinking agent;

[0011] Preferably, in the first adhesive film layer component, based on 100 parts by weight of the amount of polyvinyl butyral, the amount of copolymer microspheres can be 0.1 to 20 parts by weight, preferably 0.1 to 15 parts by weight; specifically, it can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or any value between the above values or the numerical range between any two of the above values, for example, it can be 0.1 to 10 parts by weight.

[0012] Preferably, in the second adhesive film layer component, based on 100 parts by weight of the amount of polyolefin polymer, the amount of crosslinking agent can be 0.1 to 3 parts by weight, specifically, it can be in the range of 0.1 to 1.5 or 0.1 to 1.0 or 0.1 to 0.6, etc.; the amount of co-crosslinking agent can be 0.1 to 3 parts by weight, specifically, it can be in the range of 0.1 to 1.5 or 0.1 to 1.0 or 0.1 to 0.8, etc.

[0013] Among them,

[0014] The polyvinyl butyral has a melt flow index of 0.1 to 50 g / 10 min (190 °C, 5 kg), specifically, it can be 0.1 g / 10 min, 0.2 g / 10 min, 0.3 g / 10 min, 0.4 g / 10 min, 0.5 g / 10 min, 0.6 g / 10 min, 0.7 g / 10 min, 0.8 g / 10 min, 0.9 g / 10 min, 1.0 g / 10 min, 2 g / 10 min, 3 g / 10 min, 4 g / 10 min, 5 g / 10 min, 7 g / 10 min, 8 g / 10 min, 9 g / 10 min, 10 g / 10 min, 11 g / 10 min, 12 g / 10 min, 16 g / 10 min, 18 g / 10 min, 20 g / 10 min, 22 g / 10 min, 24 g / 10 min, 26 g / 10 min, 28 g / 10 min, 30 g / 10 min, 32 g / 10 min, 34 g / 10 min, 35 g / 10 min, 36 g / 10 min, 38 g / 10 min, 40 g / 10 min, 42 g / 10 min, 45 g / 10 min, 48 g / 10 min, 50 g / 10 min, or any value between the above values or the numerical range between any two of the above values.

[0015] The polyvinyl butyral has a hydroxyl group content of 10 to 40 wt% and an aldehyde group content between 50 and 90 wt%.

[0016] The polyvinyl butyral may specifically contain the following units: 9 to 40 wt%, preferably 12 to 30 wt% of polyvinyl alcohol structural units; 50 to 90 wt%, preferably 64 to 85 wt% of polyvinyl alcohol butyral structural units; 0.5 to 10%, preferably 0.5 to 6 wt% of polyvinyl alcohol vinyl acetate structural units.

[0017] The number average molecular weight of the polyvinyl butyral is preferably 3000 to 150000, and the molecular weight distribution width is preferably 2 to 4. Specifically, its number average molecular weight can be 3000, 3500, 5000, 6000, 7000, 7500, 8000, 8500, 9000, 10000, 20000, 30000, 40000, 50000, 60000, 70000, 75000, 80000, 85000, 90000, 100000, 110000, 120000, 130000, 140000, 150000, or any value between the above values or the numerical range between any two of the above values.

[0018] The first adhesive film layer component may further contain a plasticizer;

[0019] The plasticizer may be selected from at least one of small molecule esters, sulfonamides, diols / polyethers, and polybutenes; the plasticizer is preferably selected from at least one of dicarboxylic acids or tricarboxylic acids, adipic acid esters, maleic acid esters, benzoic acid esters, epoxy vegetable oils or sulfonamides, phosphate esters, polyol esters, polyethers, polybutenes, acetylated monoglyceride ethyl citrate, or diisononyl cyclohexane-1,2-dicarboxylate;

[0020] Among them, the dicarboxylic acid or tricarboxylic acid is preferably trimellitate, more preferably at least one of trimethyl trimellitate, tris(2-ethylhexyl) trimellitate, decyl octyl trimellitate, nonyl hexyl trimellitate, and trioctyl trimellitate; and / or,

[0021] The adipic acid esters are preferably at least one of bis(2-ethylhexyl) adipate, dimethyl adipate, monomethyl adipate, dibutoxyethyl adipate, dioctyl adipate, and sebacate esters; and / or,

[0022] The maleic acid esters are preferably at least one of dibutyl maleate and diisobutyl maleate;

[0023] The epoxy vegetable oil or sulfonamide is preferably at least one of N-ethyl-p-toluenesulfonamide, N-(2-hydroxypropyl) benzenesulfonamide, and N-butyl benzenesulfonamide;

[0024] The phosphate esters are preferably at least one of tricresyl phosphate (TCP) and tributyl phosphate (TBP);

[0025] The polyol esters are selected from at least one of bis(2-ethylbutyric acid) triethylene glycol ester (3GH), 3G0 (triethylene glycol diisooctylate), triethylene glycol diisooctylate, and 4G7 (tetraethylene glycol triheptanoate);

[0026] Based on 100 parts by weight of the polyvinyl butyral, the amount of the plasticizer may be 10 to 40 parts by weight, preferably 20 to 40 parts by weight. For example, it may be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, 32, 24, 36, 38, 40 or any value between the above values or the numerical range between any two of the above values, for example, it may be 20 to 30 parts by weight.

[0027] The copolymer microspheres may be self-stabilized monodisperse copolymer microspheres having reactive groups, and the particle size is preferably 321-1251 nm; preferably, they are prepared by the preparation method of Chinese Patent CN101781387A (application number 201010130571.9, subject name: A method for copolymerization of maleic anhydride / conjugated diene). The entire content of Chinese Patent CN101781387A (application number 201010130571.9, subject name: A method for copolymerization of maleic anhydride / conjugated diene) is incorporated herein by reference.

[0028] The particle size of the copolymer microspheres may specifically be 320 nm, 350 nm, 450 nm, 550 nm, 650 nm, 750 nm, 850 nm, 950 nm, 1050 nm, 1150 nm, 1250 nm or any value between the above values or a numerical range between any two of the above values.

[0029] Specifically, the copolymer microspheres can be prepared by a method including the following steps: Under the protection of nitrogen, monomer maleic anhydride and an initiator are added to a medium and fully dissolved, then monomer conjugated diene is added and dissolved in the system, and the reaction is carried out at 50-90 °C to obtain a dispersion system of maleic anhydride and conjugated diene copolymer microspheres, and then through centrifugal separation and vacuum drying, a white solid of maleic anhydride and conjugated diene copolymer is obtained; the molar ratio of the maleic anhydride MAn to the conjugated diene is preferably 5:1-1:5.

[0030] The crosslinking agent may be at least one of organic peroxides, polyisocyanates, polyols, glycidyl ethers, acrylates, organometallic compounds, multifunctional polycarbodiimides, etc.; preferably organic peroxides. The crosslinking agent may be selected from but not limited to at least one of dicumyl peroxide, benzoyl peroxide, di-tert-butyl peroxide, cumene hydroperoxide, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, etc.

[0031] The co-crosslinking agent (also called accelerator) can be a polar multi-functional low molecular weight compound, and these monomers can be homopolymerized or grafted onto the polymer chain. Specifically, it can be selected from at least one of trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTAMA), ethylene glycol diacrylate (EGDA), ethylene glycol dimethacrylate (EGDMA), N,N'-p-phenyl bismaleimide (PDM or HVA-2), zinc diacrylate (ZDA), zinc dimethacrylate (ZDMA), etc. It can also be a compound that forms free radicals by hydrogen abstraction, such as specifically selected from at least one of triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), 1,2-polybutadiene (1,2-PBR), sulfur, etc. Preferably, it is at least one of trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTAMA), triallyl cyanurate (TAC) or triallyl isocyanurate (TAIC), etc.

[0032] The second adhesive film layer component may further contain a coupling agent;

[0033] Preferably, based on 100 parts by weight of the polyolefin polymer, the amount of the coupling agent can be 0.1 to 3 parts by weight, specifically in ranges such as 0.1 to 1.5 parts by weight or 0.1 to 1.0 parts by weight or 0.1 to 0.6 parts by weight, etc.

[0034] The coupling agent can be selected from at least one of silane coupling agents, titanate coupling agents, zirconate coupling agents, aluminate coupling agents, bimetallic coupling agents, rare earth coupling agents, phosphorus-containing coupling agents, boron-containing coupling agents; among them, the bimetallic coupling agent can be selected from at least one of aluminum-zirconate and aluminum-titanium composite coupling agents;

[0035] The silane coupling agent can be selected from at least one of polymeric silane coupling agents, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(β-methoxyethoxy)silane). The polymeric silane coupling agent can specifically be an epoxy-modified polyalkoxysiloxane silane coupling agent.

[0036] The polyolefin polymer can be an ethylene / α-olefin copolymer or a propylene / α-olefin copolymer, and its density can be 0.850 g / cm 3 ~0.920 g / cm 3 and can preferably be 0.850 g / cm 3 ~0.890 g / cm 3(The test method can refer to ASTM D792); its melt index can be 0.1 g / 10 min to 50.0 g / 10 min (ASTM D1238, under the conditions of 190 °C / 2.16 kg); the α-olefin copolymer can include but is not limited to at least one of 1-butene, 1-octene, 1-hexene, etc.).

[0037] For the polyolefin polymer, the melt flow index can specifically be 0.1 g / 10 min, 0.2 g / 10 min, 0.3 g / 10 min, 0.4 g / 10 min, 0.5 g / 10 min, 0.7 g / 10 min, 0.8 g / 10 min, 0.9 g / 10 min, 1.0 g / 10 min, 2 g / 10 min, 3 g / 10 min, 4 g / 10 min, 5 g / 10 min, 7 g / 10 min, 8 g / 10 min, 9 g / 10 min, 10 g / 10 min, 11 g / 10 min, 12 g / 10 min, 16 g / 10 min, 18 g / 10 min, 20 g / 10 min, 22 g / 10 min, 24 g / 10 min, 26 g / 10 min, 28 g / 10 min, 30 g / 10 min, 32 g / 10 min, 34 g / 10 min, 35 g / 10 min, 36 g / 10 min, 38 g / 10 min, 40 g / 10 min, 42 g / 10 min, 45 g / 10 min, 48 g / 10 min, 50 g / 10 min or any value between the above values or the numerical range between any two of the above values.

[0038] The number-average molecular weight of the polyolefin polymer can be 10,000 to 100,000, and the molecular weight distribution breadth can be 1 to 4.

[0039] The number-average molecular weight of the polyolefin polymer can specifically be 10,000, 20,000, 30,000, 40,000, 50,000, 60,000, 70,000, 75,000, 80,000, 85,000, 90,000, 100,000 or any value between the above values or the numerical range between any two of the above values.

[0040] Other additives can also be added to the co-extruded photovoltaic film composition as needed. For example, in the technical solution of this application, the addition of peroxide cross-linking agents and co-cross-linking agents is beneficial to further improve the cross-linking performance of the co-extruded film. The light stabilizer can include at least one of ultraviolet absorbers and hindered amine stabilizers. The former absorbs ultraviolet light in the spectrum, and the latter captures free radicals before the degradation reaction to avoid degradation. Adding a light stabilizer can improve the anti-aging performance of the film and maintain good mechanical properties.

[0041] Various additives can be selected and added according to actual needs, and the specific dosage is the conventional dosage, which can be adjusted according to the actual situation.

[0042] Specifically,

[0043] The first film layer component and / or the second film layer component may further contain an ultraviolet absorber; the ultraviolet absorber can be selected from the commonly used types in the art, for example, it can be selected from at least one of o-hydroxybenzophenones, benzotriazoles, salicylate esters, triazines, substituted acrylonitriles, triazine-piperidine condensates, etc. Specifically, the ultraviolet absorber can be selected from general commercially available products in the art such as ultraviolet absorber LA-31RG. Preferably, based on 100 parts by weight of polyvinyl butyral, the dosage of the ultraviolet absorber can be 0.1 to 3 parts by weight.

[0044] The first film layer component and / or the second film layer component may further contain a hindered amine stabilizer;

[0045] The hindered amine stabilizer can be a conventional type such as a derivative of 2,2,6,6-tetramethylpiperidine. Specifically, the hindered amine stabilizer products commonly used in the art can be used, such as the general product hindered amine stabilizer LA-63P in the art. Preferably, based on 100 parts by weight of polyvinyl butyral, the dosage of the hindered amine stabilizer can be 0.1 to 3 parts by weight;

[0046] The first film layer component and / or the second film layer component may further contain an antioxidant;

[0047] Preferably, based on 100 parts by weight of polyvinyl butyral, the dosage of the antioxidant can be 0.1 to 3 parts by weight;

[0048] The antioxidant can be one of 3,9-bis[1,1-dimethyl-2-[(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, methylene bis-benzotriazolyl tetramethylbutylphenol, 1,2,3,4-butanetetracarboxylic acid polymer with 2,2-bis(hydroxymethyl)-1,3-propanediol and 3-hydroxy-2,2-dimethylpropanal 1,2,2,6,6-pentamethyl-4-piperidyl ester, or a combination of two or more of them.

[0049] The preparation method of the first film layer component may include the following steps:

[0050] It is obtained by blending components including polyvinyl butyral, copolymer microspheres, optional plasticizer, optional antioxidant, and optional light stabilizer, and can be slowly stirred at a speed of 15 to 200 revolutions per minute. The ambient temperature is maintained below 20 to 40 °C. Based on 100 parts by weight of the polyvinyl butyral, the total amount of the antioxidant (if any) and the light stabilizer component (if any) can be 0.1 to 5 parts by weight.

[0051] The preparation method of the second adhesive film layer component may include the following steps:

[0052] Blend components including polyolefin polymer, crosslinking agent, co-crosslinking agent, optional coupling agent, optional antioxidant, and optional light stabilizer, and specifically blend and stir at 40 to 50 °C for 6 to 8 hours. Based on 100 parts by weight of the polyolefin polymer, the amount of the coupling agent can be 0.1 to 3 parts by weight; the total amount of the antioxidant (if any) and the light stabilizer component (if any) can be 0.1 to 5 parts by weight.

[0053] The present invention can use hindered phenol antioxidants and phosphite antioxidants as composite antioxidants, and the weight ratio of the hindered phenol antioxidant to the phosphite antioxidant can be 1:1 to 2:1, which can improve the effect of preventing thermal decomposition. By using nanoparticle microspheres, the heat and humidity resistance can be improved, the thermal shrinkage rate can be reduced, and the light transmittance is not reduced. By using light stabilizers, the light resistance of the adhesive film material can be improved and the service life can be extended. Using polymeric silane coupling agents can improve the adhesion. When selecting polymeric silane coupling agents, since no thermal cross-linking reaction occurs during the lamination of the thermoplastic polyolefin elastomer adhesive film, small molecule silane coupling agents cannot connect with the polyolefin elastomer molecules and cannot play the role of improving adhesion, and bubbles are generated. Therefore, ordinary small molecule silanes should be avoided for polymeric silane coupling agents. Polymeric silane coupling agents are those with reactive groups for inorganic substances on the side chains of polymethylsiloxane and groups that can improve the compatibility with organic substances. The polymeric siloxane main chain that can be selected is a siloxane structure, and the main chain Si atoms can be connected with alkoxy groups that react with inorganic substances, epoxy groups, hydroxyl groups, unsaturated vinyl groups that react with organic substances, and can also be connected with hydroxyl groups and polyether groups that have good compatibility with organic substances. Such as epoxy-modified polyalkoxy polysiloxane silane coupling agents. Hindered amine stabilizers and ultraviolet absorbers can also be used, and the weight ratio between the two can be between 3:1 and 1:3, which can not only improve the ultraviolet resistance but also provide protection for the photovoltaic backplane.

[0054] The second object of the present invention is to provide a co-extruded adhesive film of the co-extruded photovoltaic adhesive film composition. Preferably, the co-extruded adhesive film includes layer A and layer B, and layer A and layer B are superimposed on each other; specifically, it is an A / B / A structure or an A / B structure, etc.; layer A is a PVB adhesive film, and layer B is a POE adhesive film;

[0055] Among them, the A layer comes from the first film layer component; the B layer comes from the second film layer component.

[0056] The above-mentioned A / B / A or A / B multi-layer co-extruded film is suitable for sealing various electronic device components, especially for sealing double-glass solar cell components. In addition, it is also suitable for bonding laminated glass in the construction and automotive industries.

[0057] Preferably, the thickness of the A layer can be 80-500 microns, preferably 150-350 microns. For example, it can be 80, 85, 90, 100, 120, 150, 200, 250, 300, 350, 400, 450, 500 microns or any value between the above values or the numerical range between any two of the above values. For example, it can be 100-300 microns; the thickness of the B layer can be 50-500 microns, preferably 80-300 microns. For example, it can be 80, 85, 90, 100, 120, 150, 200, 250, 300, 350, 400, 450, 500 microns or any value between the above values or the numerical range between any two of the above values. For example, it can be 100-300 microns;

[0058] The ratio of the thickness of the A layer to the thickness of the B layer can be between 1:1 and 4:1; for example, it can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1 or any value between the above values or the numerical range between any two of the above values. For example, it can be between 2:1 and 3.5:1.

[0059] The third object of the present invention is to provide a method for preparing the co-extruded film described in the second object of the present invention, which can adopt a multi-layer co-extrusion casting or co-extrusion calendaring process.

[0060] Specifically, the method for preparing the co-extruded film may include the following steps:

[0061] One-step method, which may include the following steps: adding the first film layer component and the second film layer component into different barrels, and extruding through a layered die; the extruded materials of the first film layer component and the second film layer component are respectively melted and plasticized and then injected into the same die head, and merged into a melt flow in the T-die head, and a multi-layer composite photovoltaic co-extruded film is prepared through processes such as melt extrusion, casting film formation, cooling, slitting and winding. The temperature of the screw interval section of the first film layer is 50, 70, 100 °C respectively, and the temperature of the screw interval section of the second film layer is 70, 80, 100 °C respectively. The die head temperature can be 95-120 °C.

[0062] In specific practice, the method may include the following steps:

[0063] The components of the first adhesive film layer and the second adhesive film layer are added to different barrels. The first layer is polyvinyl butyral powder, and the second layer is a pre-crosslinked thermoplastic polyolefin elastomer, which are extruded through a stratified die.

[0064] The extruded materials of the first adhesive film layer and the second adhesive film layer are respectively melted and plasticized and then injected into the same die head, where they are combined in the T-die head to form a melt flow, and a double-layer composite photovoltaic co-extruded adhesive film is prepared through processes such as melt extrusion, casting film formation, cooling, slitting, and winding.

[0065] Among them, the temperatures of the screw interval sections of the first adhesive film layer can be 50, 70, and 100 °C respectively, and the temperatures of the screw interval sections of the second adhesive film layer can be 70, 80, and 100 °C respectively. The die head temperature is 95 - 120 °C.

[0066] The two-step method may include the following steps: (The A layer and the B layer are each formed into a film by a casting or calendering process) That is, the components of the first adhesive film layer and the second adhesive film layer are each formed into a film by a casting or calendering process, and the A layer (the first adhesive film layer, PVB adhesive film) and the B layer (the second adhesive film layer, POE adhesive film) are respectively obtained. The temperatures of the screw interval sections of the A layer can be 50, 70, and 100 °C respectively, and the temperatures of the screw interval sections of the B layer can be 70, 80, and 100 °C respectively. The die head temperature can be 100 °C. The PVB adhesive film and the POE adhesive film are respectively obtained. The two adhesive films are co-calendered in the A / B or A / B / A lamination method, the temperature of the calender roll is set to 50 - 100 °C, the A layer and the B layer pass through the calender roll simultaneously, and are drawn into a roll.

[0067] The preparation process of the multi-layer adhesive film provided by the present invention can be completed in the same die head, or after the A layer or the B layer adhesive film is respectively prepared by a casting (or calendering) method, it is calendered again through a hot calender roll to form a multi-layer adhesive film. The technical solution of the present invention can easily adjust the lamination method and thickness distribution.

[0068] The fourth object of the present invention is to provide the application of the co-extruded photovoltaic adhesive film composition or the co-extruded adhesive film of the co-extruded photovoltaic adhesive film composition or the preparation method, preferably in the applications of solar cell encapsulation, glass curtain wall, and building photovoltaic integration.

[0069] The beneficial effects of the present invention are mainly reflected in:

[0070] (1) The present invention innovatively introduces self-stabilized monodisperse copolymer microspheres with reactive groups, which have a strong binding force with polyvinyl butyral powder during the plasticization process of polyvinyl alcohol butyral, reduce the bridging phenomenon during its feeding process, and improve the processing stability.

[0071] (2) The polar bonds in polyvinyl butyral are bonded to the main chain in the form of C-C bonds, which can avoid the problem of the overflow of coupling agents after aging.

[0072] (3)Regarding the problem that the thermoplastic elastomer has weak polarity and insufficient adhesion ability with glass and the backplane, the addition of polyvinyl butyral as the skin layer increases the peel strength between the adhesive film and the glass or the backplane. That is, under the condition of achieving the same peel strength, the dosage of additives such as crosslinking agents and coupling agents in the thermoplastic elastomer can be appropriately reduced. Detailed implementation manners

[0073] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only used for further illustration of the present invention and cannot be understood as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art to the present invention based on the content of the present invention still fall within the protection scope of the present invention.

[0074] The endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0075] Source of raw materials

[0076] Polyolefin polymer, Engage 8669, Dow Chemical Company, USA; density 0.87 g / cm 3 , melt index is 14 g / min (under the condition of 190 °C / 2.16 kg), ethylene-octene copolymer, number average molecular weight is 60,000, and molecular weight distribution width is 2.16;

[0077] Peroxide, bis(tert-butylperoxyisopropyl)benzene, Akzo Nobel;

[0078] Co-crosslinking agent, trimethylolpropane trimethacrylate, Evonik;

[0079] Vinyl polysiloxane, J&Y 3654, Kaishida Company;

[0080] Polyvinyl butyral, B75H, Kuraray Co., Ltd., Japan. Melt index is 0.25 g / 10 min (190 °C, 5 kg), hydroxyl content is 19 wt%, aldehyde content is 78 wt%, number average molecular weight is 55,000, and molecular weight distribution width is 2.6;

[0081] Triethylene glycol diisooctate, PROVIPLAST 1783, Zhejiang Puweilun Chemical Co., Ltd.;

[0082] Dibutoxyethyl adipate, PROVIPLAST 0142, Zhejiang Puweilun Chemical Co., Ltd.; The mass ratio of 1783 to 0142 is 3:1, denoted as additive package A;

[0083] Hindered phenol antioxidant AO-80, ADEKA Corporation (Japan);

[0084] Phosphite antioxidant PEP-36, ADEKA Corporation (Japan);

[0085] Ultraviolet absorber LA-31RG, ADEKA Corporation (Japan);

[0086] Hindered amine stabilizer LA-63P, ADEKA Corporation (Japan);

[0087] The mass ratio of the above four additives, namely antioxidant AO-80, antioxidant PEP-36, ultraviolet absorber LA-31RG, and hindered amine stabilizer LA-63P, is 0.3:0.2:0.3:0.4 in sequence. These four additives are combined together according to this mass ratio to form additive package B.

[0088] The copolymer microspheres are prepared by the following method:

[0089] In this example, the copolymer microspheres C1 and C2 are prepared by the polymerization methods of Example 1 and Example 9 in Chinese Patent CN101781387A (application number CN201010130571.9).

[0090] The particle size of copolymer C1 is 517 nm, and the polymer particle dispersion coefficient is 1.003;

[0091] The particle size of copolymer C2 is 954 nm, and the polymer particle dispersion coefficient is 1.002.

[0092] For the raw materials used in the examples and comparative examples, if there is no special limitation, they are all disclosed in the prior art. For example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0093] Examples 1 to 6 and Comparative Examples 1 to 2

[0094] Preparation of the components of the first adhesive film (layer A):

[0095] The copolymer microspheres are blended with polyvinyl butyral powder, ester plasticizers, antioxidants, light stabilizers, etc., and slowly stirred at a speed of 20 revolutions per minute. The ambient temperature is maintained below 20°C. This raw material is the first component of the adhesive film. The polyvinyl butyral is 100 parts by mass, the plasticizer (additive package A) is 10 - 40 parts by mass, the sum of the amounts of the antioxidant and light stabilizer components (additive package B) is 0.3 - 5 parts by mass, and the copolymer microspheres are 0.1 - 20 parts by mass, preferably 0.1 - 10 parts by mass.

[0096] Preparation of the second adhesive film (layer B) component:

[0097] The thermoplastic elastomer (polyolefin polymer) is blended with peroxide crosslinking agents (di-tert-butyl peroxyisopropylbenzene), co-crosslinking agents, coupling agents, antioxidants, light stabilizers and other additives, and blended and stirred at 40 - 50°C for 6 - 8 hours. This material is the second component of the adhesive film. The thermoplastic elastomer (polyolefin polymer) is 100 parts by mass, the crosslinking agent is 0.1 - 3 parts by mass, the silane coupling agent (vinyl polysiloxane) is 0.1 - 3 parts by mass, and the co-crosslinking agent is 0.1 - 3 parts by mass. The sum of the weights of the antioxidant and light stabilizer components is 0.3 - 5 parts by mass.

[0098] The premixed polyvinyl butyral and the pre-crosslinked thermoplastic polyolefin elastomer are added to different barrels. The first layer is polyvinyl butyral powder, and the second layer is the pre-crosslinked thermoplastic polyolefin elastomer, and they are extruded through a layered die.

[0099] The extruded materials of the first adhesive film layer and the second adhesive film layer are respectively melt-plasticized and then injected into the same die head, merged into a melt flow in the T-die head, and a double-layer composite photovoltaic co-extruded adhesive film is prepared through processes such as melt extrusion, casting into a film, cooling, slitting and winding. It can be calculated by the dispenser that the thickness of the first adhesive film layer is 0.3 mm and the thickness of the second adhesive film layer is 0.1 mm. The temperatures of the screw interval sections of the first adhesive film layer are 50, 70, and 100°C respectively, and the temperatures of the screw interval sections of the second adhesive film layer are 70, 80, and 100°C respectively. The die head temperature can be 100°C.

[0100] Performance testing of the examples

[0101] The adhesive films prepared in Examples 1 - 6 and Comparative Examples 1 - 2 are used to prepare samples according to the industry standards of "JC / T 449-2014 Polyvinyl Butyral PVB Adhesive Film for Building Photovoltaic Modules Standard" and "T / CPIA 0006-2017 Copolymerized Olefin Adhesive Film for Photovoltaic Module Encapsulation", and their performances are tested.

[0102] To characterize the flow performance of the PVB powder, a special conical funnel is used to measure the time for 100 ml of the powder to freely flow and fall.

[0103] Table 1 is the cost table of the mass components of each component. Table 2 shows that after adding copolymer microspheres, the fluidity of polyvinyl butyral powder is greatly improved, changing from the original extremely easy bridging state to a powder with better fluidity.

[0104] Table 1. Composition of the mass dosage of each component (unit: parts by mass)

[0105]

[0106] Table 2. Flow properties of polyvinyl butyral powder after adding copolymer microspheres

[0107]

[0108]

[0109] Table 3 shows various relevant properties of the co-extruded film. For the co-extruded film of the present invention, through the multi-layer combination of PVB and POE, the disadvantage of high yellow index of POE itself is compensated, the defect of PVB film is avoided in terms of water vapor transmission rate, and the mechanical properties of the film such as peel strength are also greatly improved. The volume resistivity of PVB itself is relatively low, and through combination with POE, the volume resistivity of the multi-layer film can be comparable to that of POE.

[0110] Table 3. Film properties

[0111]

[0112] The above is only the preferred implementation mode of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the technical principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A co-extruded photovoltaic encapsulant composition, comprising a first encapsulant layer component and a second encapsulant layer component; The first encapsulant layer component comprises polyvinyl butyral and copolymer microspheres; The second encapsulant layer component comprises a polyolefin polymer, a crosslinking agent, and a co-crosslinking agent; Preferably, in the first encapsulant layer component, based on 100 parts by weight of the polyvinyl butyral, the amount of the copolymer microspheres is 0.1 part to 20 parts by weight, preferably 0.1 to 15 parts by weight; Preferably, in the second encapsulant layer component, based on 100 parts by weight of the polyolefin polymer, the amount of the crosslinking agent is 0.1 to 3 parts by weight; the amount of the co-crosslinking agent is 0.1 to 3 parts by weight.

2. The co-extruded photovoltaic encapsulant composition according to claim 1, characterized in that: The polyvinyl butyral has a melt flow index of 0.1 to 50 g / 10 min (190 °C, 5 kg); The number average molecular weight of the polyvinyl butyral is preferably 3000 to 150000, and the molecular weight distribution width is preferably 2 to 4.

3. The co-extruded photovoltaic encapsulant composition according to claim 1, characterized in that: The copolymer microspheres are self-stabilized monodisperse copolymer microspheres having reactive groups, and the particle size is preferably 321 to 1251 nm; preferably prepared by the following method: under the protection of nitrogen, the monomer maleic anhydride and an initiator are added to a medium and fully dissolved, then the monomer conjugated diene is added to the system and dissolved, and the reaction is carried out at 50 to 90 °C to obtain a dispersion system of maleic anhydride and conjugated diene copolymer microspheres, and then centrifuged and dried in vacuo to obtain a white solid of maleic anhydride and conjugated diene copolymer; the molar ratio of the maleic anhydride to the conjugated diene is preferably 5:1 to 1:

5.

4. The co-extruded photovoltaic encapsulant composition according to claim 1, characterized in that: The first encapsulant layer component further comprises a plasticizer; The plasticizer is selected from at least one of small molecule esters, sulfonamides, diols / polyethers, and polybutenes; the plasticizer is preferably selected from at least one of dicarboxylic acids or tricarboxylic acids, adipic acid esters, maleic acid esters, benzoic acid esters, epoxy vegetable oils or sulfonamides, phosphate esters, polyol esters, polyethers, polybutenes, acetylated monoglyceride, citrate, or diisononyl cyclohexane-1,2-dicarboxylate; Among them, the dicarboxylic acid or tricarboxylic acid is preferably a trimellitate, more preferably at least one of trimethyl trimellitate, tris(2-ethylhexyl) trimellitate, decyl octyl trimellitate, nonyl hexyl trimellitate, and trioctyl trimellitate; and / or, The adipic acid esters are preferably at least one of bis(2-ethylhexyl) adipate, dimethyl adipate, monomethyl adipate, dibutoxyethyl adipate, dioctyl adipate, and sebacate esters; and / or, The maleic acid esters are preferably at least one of dibutyl maleate and diisobutyl maleate; The epoxy vegetable oil or sulfonamide is preferably at least one of N-ethyl-p-toluenesulfonamide, N-(2-hydroxypropyl)benzenesulfonamide, and N-butylbenzenesulfonamide; The phosphate esters are preferably selected from at least one of tricresyl phosphate (TCP) and tributyl phosphate (TBP); The polyol esters are preferably selected from at least one of bis(2-ethylbutyric acid) triethylene glycol ester (3GH), 3G0 (triethylene glycol diisooctanoate), triethylene glycol diisooctanoate, and tetraethylene glycol triethyleneglycol heptanoate (4G7); Preferably, based on 100 parts by weight of the polyvinyl butyral, the amount of the plasticizer is 10 to 40 parts by weight, preferably 20 to 40 parts by weight.

5. The coextruded photovoltaic film composition according to claim 1, characterized in that: The second film layer component further comprises a coupling agent; Preferably, based on 100 parts by weight of the polyolefin polymer, the amount of the coupling agent is 0.1 to 3 parts by weight; Preferably, the coupling agent is selected from at least one of silane coupling agents, titanate coupling agents, zirconate coupling agents, aluminate coupling agents, bimetallic coupling agents, rare earth coupling agents, phosphorus-containing coupling agents, and boron-containing coupling agents; wherein the bimetallic coupling agent is preferably selected from at least one of aluminum-zirconate and aluminum-titanium composite coupling agents; The silane coupling agent is preferably selected from at least one of polymeric silane coupling agents, vinyltriethoxysilane, vinyltrimethoxysilane, and vinyltris(β-methoxyethoxy)silane); the polymeric silane coupling agent is preferably an epoxy-modified polyalkoxysiloxane silane coupling agent.

6. The coextruded photovoltaic film composition according to claim 1, characterized in that: The polyolefin polymer is an ethylene / α-olefin copolymer or a propylene / α-olefin copolymer, and its density is preferably 0.850 g / cm 3 to 0.920 g / cm 3 , preferably 0.850 g / cm 3 to 0.890 g / cm 3 ; its melt index is preferably 0.1 g / 10 min to 50.0 g / 10 min (under the conditions of 190 °C / 2.16 kg); the α-olefin copolymer is preferably selected from at least one of 1-butene, 1-octene, and 1-hexene; The number average molecular weight of the polyolefin polymer is preferably 10,000 to 100,000, and the molecular weight distribution width is preferably 1 to 4.

7. The coextruded photovoltaic film composition according to claim 1, characterized in that: The crosslinking agent is at least one of organic peroxides, polyisocyanates, polyols, glycidyl ethers, acrylates, metal organic compounds, and multifunctional polycarbodiimides; preferably an organic peroxide; preferably, the crosslinking agent is selected from at least one of dicumyl peroxide, benzoyl peroxide, di-tert-butyl peroxide, cumene hydroperoxide, and 2,5-dimethyl-2,5-di-tert-butylperoxyhexane; and / or, The co-crosslinking agent is selected from at least one of trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTAMA), trimethylolpropane trimethacrylate (TMPTMA), ethylene glycol diacrylate (EGDA), ethylene glycol dimethacrylate (EGDMA), N,N'-p-phenyl bismaleimide (PDM or HVA-2), zinc diacrylate (ZDA), zinc dimethacrylate (ZDMA), triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), 1,2-polybutadiene (1,2-PBR), and sulfur; preferably at least one of trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTAMA), trimethylolpropane trimethacrylate (TMPTMA), triallyl cyanurate (TAC), or triallyl isocyanurate (TAIC).

8. The method for preparing the co-extruded photovoltaic film composition according to any one of claims 1 to 7, characterized in that it comprises the following steps: The method for preparing the first film layer component comprises the following steps: Mixing components including polyvinyl butyral, copolymer microspheres, optional plasticizer, optional antioxidant, and optional light stabilizer to obtain; the mixing speed is preferably 15 to 200 revolutions per minute, and the mixing temperature is preferably 20 to 40 °C; and / or, The method for preparing the second film layer component comprises the following steps: Mixing components including polyolefin polymer, crosslinking agent, co-crosslinking agent, optional coupling agent, optional antioxidant, and optional light stabilizer, and the mixing temperature is preferably 40 to 50 °C; preferably, based on 100 parts by weight of the polyolefin polymer, the total amount of the antioxidant and light stabilizer components is 0.1 to 5 parts by weight.

9. The co-extruded film of the co-extruded photovoltaic film composition according to any one of claims 1 to 7, preferably, the co-extruded film comprises layer A and layer B, and layer A and layer B are superposed on each other; preferably, it is of A / B / A structure or A / B structure; wherein, Layer A is from the first film layer component; layer B is from the second film layer component; Preferably, the thickness of layer A is 80 to 500 microns, preferably 150 to 350 microns; the thickness of layer B is 50 to 500 microns, preferably 80 to 300 microns; The ratio of the thickness of layer A to the thickness of layer B is preferably 1:1 to 4:1; more preferably 2:1 to 3.5:

1.

10. The method for preparing the co-extruded film according to claim 9, characterized in that it is prepared by a multi-layer co-extrusion casting or co-extrusion calendering process.

11. The method for preparing the co-extruded film according to claim 10, characterized in that it is selected from one of the following methods: Method 1, comprising the following steps: adding the first film layer component and the second film layer component into different barrels, and extruding through a stratified die; The extruded materials of the first film layer component and the extruded materials of the second film layer component are respectively melt-plasticized and then injected into the same die head, and after melt-extrusion, casting into a film, and cooling, a multi-layer composite photovoltaic co-extruded film is prepared; Or, Method 2 includes the following steps: The first adhesive film layer component and the second adhesive film layer component are each formed into a film by a casting or calendering process to obtain layer A and layer B respectively. The temperature of the calender roll is set at 50-100 °C. Layer A and layer B pass through the calender roll simultaneously and are drawn into a roll.

12. Use of the coextruded photovoltaic adhesive film composition according to any one of claims 1 to 7, or the coextruded adhesive film of the coextruded photovoltaic adhesive film composition according to claim 9, or the preparation method according to claim 10 or 11, preferably for use in solar cell encapsulation, glass curtain walls, and building-integrated photovoltaics.

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