JPS6214111B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a filled adhesive sheet for solar cells and an adhesion method using the same. For more details,
The present invention relates to a filled adhesive sheet for solar cells exhibiting improved adhesion and an adhesion method using the same. In recent years, it has been pointed out that existing energy sources, mainly oil, have been depleted, and the development of alternative energy sources has become necessary.In this context, solar power generation has been recognized as a clean energy source and as a source of inexhaustible solar radiation energy. There is a desire for its immediate practical application and widespread use. Photovoltaic power generation uses solar cells to directly convert the sun's radiant energy into electrical energy, and this function is obtained by utilizing the quantum effect of semiconductors, generally silicon semiconductors, selenium semiconductors, etc. By the way, the functionality of silicon semiconductors deteriorates when directly exposed to the outside air, so for the purpose of protection from the outside air, we use transparent upper protective materials made of glass, acrylic resin, carbonate resin, etc., and glass, stainless steel, and aluminum. , and is protected by a lower substrate protection material made of plastic or the like. At this time, the high-performance silicon semiconductors used for solar power generation are usually wafers (small thin film pieces), so these wafers are arranged in series or parallel using interconnectors, electrically connected and fixed. Because of this need, filler adhesives are commonly used. The physical properties required of this filling adhesive include the following. (1) In order to prevent wafers such as silicon semiconductors from being destroyed by internal strain caused by thermal expansion and contraction, they must have elastomeric properties. (2) Power generation is possible only after sunlight passes through the external protective material, filling adhesive, and silicon semiconductor in order, so the filling adhesive used during this time must have high sunlight transmittance. Must be. (3) Must have good adhesion to external protective materials. (4) Wafers such as silicon semiconductors have a small starting force, so a useful voltage can be obtained by connecting wafers in series or in parallel, so the connecting material must not corrode and have high dielectric strength. (5) There is no change in each of the above properties after being left outdoors for a long period of time. Conventionally, heat-crosslinking liquid silicone resins have been used as having these properties, but
This had drawbacks such as being expensive, requiring long coating and bonding steps, and being unsuitable for automation. For this reason, sheets of polyvinyl petral resin, which has a proven track record for laminated glass, have recently begun to be used, but this is not necessarily satisfactory as a filler adhesive for solar cells. That is, a polyvinyl butyral sheet has starch or sodium bicarbonate attached to its surface to prevent blocking, and must be washed with water, dried, and conditioned before use. In addition, it is necessary to use an autoclave for bonding due to the poor fluidity of the resin, which requires a long process time.
Not suitable for automation. Furthermore, in terms of quality, due to its high water absorption rate, it has poor humidity characteristics, and if left in high humidity for a long time, it will cause devitrification, which not only reduces light transmittance but also significantly reduces adhesive strength. death,
A peeling phenomenon occurs at the interface between the upper transparent protective material, the lower substrate protective material, and the solar cell element. Furthermore, low-temperature properties (flexibility) are not necessarily good. In place of polyvinyl butyral sheets, which have these problems, ethylene-vinyl acetate copolymer sheets have recently begun to be considered from the perspective of reducing the cost of solar cell modules. However, the commonly used ethylene-vinyl acetate copolymer cannot satisfy the characteristics required as a filler adhesive for solar cells. That is, as the vinyl acetate content in this copolymer increases, transparency and flexibility improve, but sheet formability and
Blocking properties deteriorate, making it difficult to satisfy both properties at the same time, and heat resistance,
Light resistance is also insufficient. Furthermore, the durable adhesiveness with the upper transparent protective material and the lower substrate protective material, which determines the reliability of the solar cell module, is also insufficient. The present inventors used an ethylene-based copolymer resin such as ethylene-vinyl acetate copolymer to achieve various properties required for a filling adhesive for solar cells, especially excellent initial adhesion and durable adhesion with protective materials. As a result of various studies in search of a filled adhesive sheet suitable for automating and shortening the bonding process and a bonding method using the same, a sheet molded from an ethylene copolymer resin containing a coupling agent and an organic peroxide was developed. The present invention has been completed based on the discovery that a sheet is fully suitable for such purposes. Accordingly, the present invention relates to a filled adhesive sheet for solar cells, which is made of an ethylene copolymer resin containing a coupling agent and an organic peroxide. The present invention also relates to a method for adhering a protective material for a solar cell and a filler, and the adhesion between the protective material and the filler is performed by adhering the solar cell element to an ethylene copolymer resin containing a coupling agent and an organic peroxide. sandwiched between at least two filled adhesive sheets consisting of at least two filled adhesive sheets, with an upper transparent protective material and a lower substrate protective material layered on both sides, or an ethylene copolymer resin containing a coupling agent and an organic peroxide. An upper transparent protective material and a lower substrate protective material each having a solar cell element formed on the inward surface of one of the protective materials were stacked above and below the intermediate layer filled adhesive sheet. In the module bonding process in this state, heating is performed to a temperature higher than the decomposition temperature of the organic peroxide. The ethylene copolymer resin has a light transmittance of about 80% or more, preferably about 90% or more, and an elastic modulus of about 1 to 30 MPa, preferably about 3 to 12 MPa.
are used as suitable copolymer resins.
Specifically, for example, copolymers of ethylene and vinyl esters such as vinyl acetate and vinyl propionate, copolymers of ethylene and unsaturated fatty acid esters such as ethyl acrylate, butyl acrylate, and methyl methacrylate, and ethylene. and copolymers with α-olefins such as propylene, butene-1, and 4-methylpentene-1, as well as ethylene-vinyl ester-unsaturated fatty acid ternary copolymers, ethylene-unsaturated fatty acid ester-unsaturated fatty acid Tertiary copolymers or their metal salts (ionomer resins)
etc. are used. Among these ethylene-based copolymer resins, the most preferred one from an economic point of view is an ethylene-vinyl acetate copolymer, in which case the vinyl acetate content in the copolymer is about 20 to 40% by weight, preferably is about 25
~40% by weight is suitable. If the vinyl acetate content is less than this, the light transmittance will be low and the power generation efficiency of the module will be low, and the elastic modulus will be high and the power generation element will undergo thermal expansion and contraction.
The risk of damage increases. However, in the case where a filling adhesive sheet is pasted under the solar cell element formed on the lower surface of the upper transparent protective material, the light transmittance of that part is irrelevant, so the vinyl acetate content is approximately 20% by weight. The following ethylene-vinyl acetate copolymers can also be used. On the other hand, if the vinyl acetate content increases beyond this range, the extrusion moldability of the sheet will deteriorate, and the resulting sheet will become more sticky and prone to blocking. These ethylene copolymer resins contain a coupling agent and an organic peroxide. As the coupling agent, one is used that has a good adhesion function when the ethylene copolymer resin containing the organic peroxide is heat bonded to each external protective material in the coexistence of the organic peroxide. Such a coupling agent may have the general formula RSiX ₃ (where R is a reactive organic group such as a vinyl group, an aminoalkyl group, a methacryloxyalkyl group, an acryloxyalkyl group, a mercaptoalkyl group, or an epoxy group, and X is a halogen group). an organosilane compound with the general formula R′ _4-o Si(OOR″) _o (where R′ is a vinyl group or an alkyl group). can be,
R″ is a hydrocarbon group, n is an integer from 1 to 4) or an organosilane peroxide represented by the general formula ROTi(OYRZ) ₃ (where R is an alkyl group and Y is a carboxyl group) , a phosphate group, a pyrophosphate group, a phosphite group, or a sulfonyl group, and Z is a hydrogen atom, an amino group, a hydroxyl group, a mercapto group, an acrylic group, or a methacrylic group). In addition to the above-mentioned adhesion function, these coupling agents are characterized by their kneadability and compatibility with the ethylene copolymer resin, odor, light resistance, non-corrosion against interconnectors, cost, etc. From this point of view, preferred coupling agents include vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, and γ
-methacryloxypropyltrimethoxysilane,
Organic compounds with unsaturated groups or epoxy groups such as vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. It is a silane compound. When an organosilane peroxide is used as a coupling agent, its decomposition temperature (temperature at which the half-life is 1 hour) is approximately 90 to 190°C, preferably approximately 120 to 190°C.
A temperature of 160℃ is suitable. Such organosilane peroxides include CH ₃ Si(OO-t-Bu) ₃ ,
Examples include CH ₂ --CHSi(OOR'') (where R'' is a tertiary butyl group, a cumyl group, or a p-menthyl group). These coupling agents are generally used in an amount of about 0.1 to 10 parts by weight, preferably about 0.5 parts by weight, based on 100 parts by weight of the ethylene copolymer resin.
It is used in a proportion of ~5 parts by weight. The combination of this and the organic peroxide provides stronger adhesion between the ethylene copolymer resin and each external protective material, which is useful in practice. That is, compared to using only a coupling agent or an organic peroxide,
Adhesion is clearly improved when these are used in combination. The cause of this is not fully understood, but for example, when a silane coupling agent with an unsaturated group is used, the organic peroxide decomposes during heating and bonding, generating radicals in the ethylene copolymer resin. The majority of these polymer radicals appear to be involved in the crosslinking reaction of the ethylene copolymer resin, but the remaining part reacts with the unsaturated groups of the silane coupling agent, meaning that the coupling agent is grafted onto the ethylene copolymer resin. It is also believed that this grafted coupling agent exists between the ethylene copolymer resin and each external protective material and is involved in the formation of stronger adhesion. Organosilane peroxides used as coupling agents are also thought to have the function of crosslinking ethylene copolymer resins, similar to the organic peroxides used in combination, but their crosslinking efficiency is lower than that of organic peroxides. is also inferior and disadvantageous in terms of cost,
It is not preferable to use organic silane peroxide as a substitute for organic peroxide, and it is preferable to use both in combination. Organic peroxides used in combination with coupling agents (thus, organic silane peroxides are naturally excluded) must be A material that does not decompose but quickly decomposes at a temperature below the decomposition temperature of the ethylene copolymer resin during the modularization process is used. Generally, about 90~
Those having a decomposition temperature (temperature at which the half-life is 1 hour) of 190°C, preferably about 120-160°C are used. Examples of such organic peroxides include tert-butyl peroxyisopropyl carbonate, tert-butyl peroxy acetate, tert-butyl peroxybenzoate, dicumyl peroxide, 2,
5-dimethyl-2,5-bis(tert-butylperoxy)hexane, di-tert-butyl peroxide,
2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyl-3,1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert-butylperoxy)cyclohexane, methyl ethyl ketone peroxide, 2,5-dimethylhexyl-2,5-
Bisperoxybenzoate, tert-butyl hydroperoxide, p-menthane hydroperoxide, benzoyl peroxide, p-chlorobenzoyl peroxide, tert-butyl peroxyisobutyrate, hydroxyheptyl peroxide, cyclohexanone peroxide - Examples include oxide. These organic peroxides crosslink the ethylene copolymer resin during heating during the bonding process of solar cell modules, improve heat resistance, and cause interaction between the coupling agent and the filling adhesive. It is added in an amount necessary to contribute to improved adhesion. Generally, about 0.1 to 5 parts by weight, preferably about 0.5 to 3 parts by weight, of organic peroxide is added to 100 parts by weight of the ethylene copolymer resin. If the addition ratio is less than this, transparency, heat resistance, and adhesion between the filling adhesive and each external protective material will not be sufficient. When stricter light resistance is required for the filled adhesive, it is preferable to add a light resistance stabilizer, such as 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy- 4-
Methoxybenzophenone, 2-hydroxy-4-
Methoxy-2'-carboxybenzophenone, 2-
Benzophenones such as hydroxy-4-n-octoxybenzophenone, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-5-methylphenyl) Benzotriazole types such as benzotriazole and 2-(2'-hydroxy-5-tertiary octylphenyl)benzotriazole, salicylic acid ester types such as phenyl salicylate and p-octylphenyl salicylate, and nickel complex salt types. , hindered amine type, etc. are used as light stabilizers. When these light stabilizers are used in combination with antioxidants such as hindered phenols and phosphites, a synergistic effect may be expected. The forming of the sheet used as a filling adhesive is
This can be carried out by a known method using a T-die extruder or the like. That is, the ethylene copolymer resin, coupling agent, organic peroxide, and optionally added light stabilizer are dry blended in advance and supplied from the hopper of the extruder, so that the organic peroxide does not substantially decompose. Molding is carried out by extrusion into a sheet at a molding temperature, preferably through an embossed take-off roll. Formation of an arbitrary embossed pattern is effective for preventing blocking of the sheet and for degassing during the modularization process of solar cells. Although the thickness of the sheet is not particularly limited, it is generally about 0.1 to 1 mm. In addition, if the coupling agent, organic peroxide, etc. are in the form of a solution or are used as a solution, an extruder with a well-known vent function is used.
Either prepare pellets from which the solvent has been removed in advance, and then go through the above steps, or install a T-die directly at the tip of an extruder with a vent function, and form the pellets into sheets at once while removing the solvent using the vent device. You can also take the following method. Modularization of solar cells can be carried out as follows. When solar cell elements are made of silicon semiconductor or selenium semiconductor wafers, these solar cell elements are sandwiched between at least two filled adhesive sheets, and if necessary, surface active material is applied to both sides of the sheets. A protective material that has been cleaned with a chemical solution or an organic solvent, or surface treated with corona discharge or chemicals, that is, an upper transparent protective material and a lower substrate protective material are layered and degassed by applying a vacuum. Afterwards or at the same time, it is heated and then pressurized to adhere and bond. At this time, it is industrially preferable to bond the module by sequentially overlapping or arranging the lower substrate protective material, the filling adhesive sheet, the solar cell element, the filling adhesive sheet, and the upper transparent protective material. The battery element may be laminated in advance with at least two filled adhesive sheets made of an ethylene copolymer resin containing a coupling agent and an organic peroxide, and bonded to the upper transparent protective material and the lower substrate protective material. Heating is preferably carried out until the organic peroxide added to the filled adhesive sheet is almost completely decomposed. Through this heat treatment, the filling adhesive is cross-linked, the filling adhesive and each external protective material are firmly adhered, and the solar cell element is laminated with two filling adhesive sheets, and the upper transparent A solar cell module is formed therein, which is firmly bonded to the protective material and the lower substrate protective material. The heat treatment performed here is preferably performed in two stages. In other words, under conditions where the organic peroxide does not completely decompose and the module adheres gently, for example, when the organic peroxide has a decomposition temperature of 140°C, the decomposition temperature is about 0.1 in a vacuum laminator at 140°C.
Industrially, it is possible to carry out the temporary bonding process for ~5 minutes and the heating process under conditions such that the peroxide is almost completely decomposed, such as heating at 140°C for about 60 to 200 minutes at room temperature, in separate processes. It's advantageous. The reason is as follows. (1) Temporary bonding requires an expensive vacuum laminator, so in order to increase the production capacity of the temporary bonding process that uses this laminator, it is possible to replace the temporary bonding process with the temporary bonding process without using this laminator. It is advantageous to carry out the process in two stages: heating under normal pressure. (2) When heating and pressurizing are continued in a vacuum laminator, the filling adhesive sheet melts and flows, and some of it flows out from the edge of the panel, resulting in short circuits and filling of the solar cell elements due to misalignment. As the thickness of the adhesive sheet layer becomes thinner, the insulation (withstanding) voltage between the solar cell element or interconnector and the lower substrate protection material decreases, but this can be avoided by heating in two stages. be able to prevent undesirable phenomena such as Incidentally, the temporarily bonded laminate can be once cooled and then subjected to the next heating step, but as long as work permits, it is preferable not to cool it because the amount of heat required is smaller. In addition, solar cell elements are made of glass, plastic,
When formed on a protective material such as ceramic or stainless steel, a filled adhesive sheet is used as an intermediate layer, and a solar cell element is formed on the inward facing surface (contact surface of the filled adhesive sheet) of one of the protective materials. With the upper transparent protective material and the lower substrate protective material layered on top and bottom of the intermediate layer filling adhesive sheet, specifically, the filling adhesive sheet is placed on top of the solar cell element formed on the upper surface of the lower substrate protective material. Then, with the filling adhesive sheet and the lower substrate protective material sequentially stacked under the lower transparent protective material or the solar cell element formed on the lower surface of the upper transparent protective material, this is placed under vacuum in the same manner as in the above case. When heat bonding is performed, a solar cell module is formed in which one protective material on which a solar cell element is formed, a filling adhesive sheet, and the other protective material are firmly bonded together. In this way, the solar cell formed by bonding by the method using the filling adhesive sheet according to the present invention has a high peel strength between the protective material and the filling adhesive, and has good peeling resistance under humid conditions. It fully satisfies all the properties required for solar cell modules, such as excellent initial adhesion and durable adhesion, little change in response to UV irradiation, and good light transmittance. It also has the effect of enabling automated and shortened bonding. Next, the present invention will be explained with reference to examples. Example 1 Ethylene-vinyl acetate copolymer (Mitsui Polychemical product Evaflex 250, vinyl acetate content 28
Weight%, melt index 15) 100 parts (weight,
(same below), tertiary butyl peroxybenzoate
1.5 parts, 1 part of γ-methacryloxypropyltrimethoxysilane, 0.3 parts of 2-hydroxy-4-n-octylbenzophenone, and tetrakis-[methylene-3-(3',5'-di-tert-butyl-4') -Hydroxyphenyl)propionate] A mixture prepared by dry blending 0.1 part of methane was extruded into a sheet at a resin temperature of 95°C using a T-die extrusion molding machine, and the sheet was taken off with an embossed pattern take-up roll. , thickness with embossed patterns on both sides of the sheet
A 0.5 mm embossed sheet was molded. Modularization of solar cells using this embossed sheet was carried out as follows. After washing the surface with a neutral detergent aqueous solution, washing with distilled water and air drying the white plate glass (thickness: 3 mm,
The embossed sheet is placed on the embossed sheet (light transmittance of 91% at 450 mμ), and a plurality of silicon semiconductor wafers for solar cells (element light-receiving area 18 cm ² / piece) are arranged in series on it using an interconnector,
In addition, the embossed sheet and polyvinyl vinyl sheet (Tedlar 400BS, manufactured by DuPont, USA)
30WH) were stacked one on top of the other and melted and bonded using a vacuum laminator at a heating temperature of 110°C (temporary bonding). This temporary adhesive laminate is further placed under normal pressure.
By heating on a hot plate at 150°C for 30 minutes, the organic peroxide was decomposed, the ethylene-vinyl acetate copolymer was crosslinked, and a module was produced that was firmly adhered to each external protective material. When measuring the power generation performance of this solar cell module, the short ^- circuit current was
A value of 370 mA/18 cm ² and a voltage of 6 V/18 cm ² were obtained. Example 2 The white glass-embossed sheet-polyfluorinated vinyl sheet laminates used in Example 1 were prepared in the same manner as in Example 1, and the peel strength of the laminates was measured using a tensile tester at a tensile speed of 20 cm. /
The measurement was performed by T-peeling under the conditions of 23° C., 60% relative humidity, and the average value of 5 samples was calculated. As shown in the results in the table below, good peel strength was observed between the embossed sheet and the white glass or polyfluorinated vinyl sheet. Example 3 The white glass-embossed sheet-white glass laminate used in Example 1 was prepared in Example 1.
The laminate was prepared using a UV meter to measure the light transmittance at a wavelength of 500 mμ, and an ultraviolet irradiator was used to continuously irradiate it with ultraviolet light for 100 hours and observe its appearance. As shown in the results in the table below, the light transmittance was good and the appearance when irradiated with ultraviolet rays was also good. Example 4 The module produced in Example 1 was subjected to a temperature cycle test and a humidity cycle test. In the temperature cycle test, high temperature (+90
When the appearance of the module was observed after 20 cycles of 4 hours each at low temperature (-40°C) and low temperature (-40°C), no abnormality was observed. Humidity cycle test: 90% phase humidity, 16 hours under 40℃ atmosphere, 90℃ relative humidity,
When the appearance of the module was observed after 20 cycles of 6 hours per cycle in an atmosphere at 23°C, no abnormality was found. From the results of Examples 1 to 4 above, the sheet containing the ethylene copolymer resin, coupling agent, and organic peroxide used in the present invention is extremely useful as a filling adhesive sheet for solar cells. I understand. Example 5 Ethylene-vinyl acetate copolymer (Mitsui Polychemical product Evaflex 150, vinyl acetate content 33
Weight%, melt index 30) 100 parts, 2,5
-Dimethyl-2,5-bis(tert-butylperoxy)hexane 1.5 parts, γ-methacryloxypropyltrimethoxysilane 1 part, 2-hydroxy-4
-0.3 part of n-octylbenzophenone, 0.1 part of bis(2,2,6,6-tetramethyl-4-piperidine) sebacate and tris (mixed mono-
An embossed sheet was formed in the same manner as in Example 1 using a mixture obtained by doratoblending 0.2 parts of dinonyl phenyl) phosphite, and a solar cell module was produced using this embossed sheet. Example 6 The white glass-embossed sheet-polyfluorinated vinyl sheet laminates used in Example 5 were prepared in the same manner as in Example 1, and the peel strength of the laminates was measured in the same manner as in Example 2. As shown in the results in the table below, good peel strength was observed between the embossed sheet and the white glass or polyfluorinated vinyl sheet. Example 7 The white glass-embossed sheet-white glass laminates used in Example 5 were produced in the same manner as in Example 1, and the laminates were measured for light transmittance and irradiated with ultraviolet rays in the same manner as in Example 3. I conducted a test. As shown in the results in the table below, the light transmittance was good and the appearance when irradiated with ultraviolet rays was also good. Example 8 In Example 1, the same amount of γ-glycidoxypropyltrimethoxysilane was used instead of γ-methacryloxypropyltrimethoxysilane, and an embossed sheet was formed and a solar cell module was produced using this embossed sheet. I did this. Example 9 The white glass-embossed sheet-polyfluorinated vinyl sheet laminates used in Example 8 were produced in the same manner as in Example 1, and the peel strength of this laminate was measured in the same manner as in Example 2. The results are shown in the table below. Example 10 In Example 1, the same amount of γ-mercaptopropyltrimethoxysilane was used instead of γ-methacryloxypropyltrimethoxysilane, and an embossed sheet was formed and a solar cell module was produced using this embossed sheet. Summer. Example 11 The white glass-embossed sheet-polyfluorinated vinyl sheet laminate used in Example 10 was produced in the same manner as in Example 1, and the peel strength of this laminate was measured in the same manner as in Example 2. The results are shown in the table below. Example 12 In Example 1, CH ₂ -CH- was substituted for 1 part of γ-methacryloxypropyltrimethoxysilane.
Using 3 parts of a 30% by weight toluene solution of Si-(OO-t-Bu) ₃ (Shin-Etsu Silicon Products X-12-530), this silane compound solution and ethylene-vinyl acetate copolymer were blended and vent extruded. A pellet was prepared by extruding the resin at a resin temperature of 90° C. using a machine to remove toluene, and other ingredients were added to the pellet to form an embossed sheet. A solar cell module was also produced using this embossed sheet. Example 13 The white glass-embossed sheet-polyfluorinated vinyl sheet laminates used in Example 12 were produced in the same manner as in Example 1, and the peel strength of this laminate was measured in the same manner as in Example 2. The results are shown in the table below. Example 14 In Example 1, the same amount of vinyltriethoxysilane was used in place of γ-methacryloxypropyltrimethoxysilane, and an embossed sheet was formed and a solar cell module was produced using this embossed sheet. Example 15 The white glass-embossed sheet-polyfluorinated vinyl sheet laminates used in Example 14 were produced in the same manner as in Example 1, and the peel strength of this laminate was measured in the same manner as in Example 2. The results are shown in the table below. Comparative Example 1 In Example 1, an embossed sheet was molded without using γ-methacryloxypropyltrimethoxysilane. Using this embossed sheet, a white plate glass-embossed sheet-polyfluorinated vinyl sheet laminate was prepared in the same manner as in Example 2, and the peel strength of this laminate was measured in the same manner as in Example 2. As shown in the results in the table below, practically sufficient adhesive strength could not be obtained between the embossed sheet and the white glass or polyfluorinated vinyl sheet. Comparative Example 2 In Example 5, 2,5-dimethyl-2,5
- An embossed sheet was molded without using bis(tert-butylperoxy)hexane. Using this embossed sheet, white plate glass was prepared in the same manner as in Example 2.
An embossed sheet-polyfluorinated vinyl sheet laminate was prepared, and the peel strength of this laminate was measured in the same manner as in Example 2. As shown in the results in the table below, practically sufficient adhesive strength could not be obtained between the embossed sheet and the white glass or polyfluorinated vinyl sheet. From the comparison of Examples 2, 6, 9, and 11 and Comparative Examples 1 and 2 above, it can be seen that in these laminates, the reaction between the coupling agent and the organic peroxide greatly contributes to the adhesion between each layer. It can be seen that Comparative Example 3 In Example 1, an ethylene-vinyl acetate copolymer with a vinyl acetate content of 45% by weight (Evaflex, a Mitsui Polychemical product) was used instead of the vinyl acetate copolymer with a vinyl acetate content of 28% by weight.
45X, melt index 80) was used to form an embossed sheet, but the adhesion to the take-up roll was significant and it was not possible to obtain a satisfactory embossed sheet. Comparative Example 4 In Example 1, the vinyl acetate content was 28% by weight.
14% by weight ethylene-vinyl acetate copolymer (Mitsui Polychemical product Evaflex) instead of
550, melt index 15) to form an embossed sheet (however, the resin temperature is 110
C), using this embossed sheet, a white plate glass-embossed sheet-white plate glass laminate was produced in the same manner as in Example 3, and the light transmittance of this laminate was measured, and the results are shown in the table below. From the comparison of Examples 1, 3, 5, and 7 and Comparative Examples 3 and 4 above, it is clear that it is preferable to use an ethylene-vinyl acetate copolymer having a vinyl acetate content of about 20 to 40% by weight. Comparative Example 5 In Example 1, an embossed sheet was formed using only the ethylene-vinyl acetate copolymer, and this embossed sheet was used to laminate white glass, embossed sheet, and polyvinyl fluoride sheet in the same manner as in Example 2. A product was prepared, and the peel strength of this laminate was measured in the same manner as in Example 2. As shown in the results in the table below, practically insufficient adhesive strength was obtained between the embossed sheet and the white glass or polyfluorinated vinyl sheet. Comparative Example 6 Starch adhering to the surface of a butyral resin sheet (DuPont product Butasite) was washed with water to remove it, dried, and the humidity conditioned, then used as the intermediate layer and heated at 160°C under pressure using an autoclave.
A laminate was prepared by melt-bonding the white glass and the polyvinyl fluoride sheet for 30 minutes, and the peel strength of this laminate was measured in the same manner as in Example 2. The results are shown in the table below. Indicated.

【table】

[Table] Example 16 The embossed sheet and polyfluorinated vinyl sheet obtained in Example 1 were sequentially stacked on top of the solar cell element formed on the white glass substrate, and the module was laminated in the same manner as in Example 1. I did this. The obtained solar cell module was subjected to a temperature cycle test and a humidity cycle test in the same manner as in Example 4. 20 in temperature cycle test
When the appearance of the module was observed after 20 cycles and humidity cycle tests, no abnormalities were found in any of them.

Claims (1)

[Scope of Claims] 1. A filled adhesive sheet for solar cells comprising an ethylene copolymer resin containing a coupling agent and an organic peroxide. 2. The filled adhesive sheet according to claim 1, wherein an organic silane compound, an organic silane peroxide, or an organic titanate compound is used as a coupling agent. 3. The filled adhesive sheet according to claim 1, wherein an organic peroxide having a decomposition temperature of about 90 to 190°C is used. 4. The filled adhesive sheet according to claim 1, wherein an ethylene-vinyl acetate copolymer having a vinyl acetate content of about 40% by weight or less is used as the ethylene-based copolymer resin. 5. The filled adhesive sheet according to claim 1, wherein an ethylene-vinyl acetate copolymer having a vinyl acetate content of about 20 to 40% by weight is used as the ethylene-based copolymer resin. 6. A solar cell element is sandwiched between at least two filled adhesive sheets made of an ethylene copolymer resin containing a coupling agent and an organic peroxide, and an upper transparent protective material and a lower substrate protective material are layered on both sides. 1. A method for adhering a solar cell protective material and a filler, the method comprising heating the organic peroxide to a temperature higher than the decomposition temperature of the organic peroxide in the module bonding process in a state in which the organic peroxide is decomposed. 7. The bonding method according to claim 6, wherein the lower substrate protective material, the filling adhesive sheet, the solar cell element, the filling adhesive sheet, and the upper transparent protective material are sequentially stacked or arranged to bond the module. 8. The bonding method according to claim 6, wherein an organic silane compound, an organic silane peroxide, or an organic titanate compound is used as the coupling agent. 9. The bonding method according to claim 6, wherein an organic peroxide having a decomposition temperature of about 90 to 190°C is used. 10. The bonding method according to claim 6, wherein an ethylene-vinyl acetate copolymer having a vinyl acetate content of about 20 to 40% by weight is used as the ethylene copolymer resin molded into the filled adhesive sheet. 11. The bonding method according to claim 6, wherein the solar cell element is laminated in advance with at least two filled adhesive sheets and bonded to the upper transparent protective material and the lower substrate protective material. 12 An upper transparent protective material with a filled adhesive sheet made of an ethylene copolymer resin containing a coupling agent and an organic peroxide as an intermediate layer, and a solar cell element formed on the inner surface of one of the protective materials; A solar cell protective material and filling, characterized in that the lower substrate protective material is heated above the decomposition temperature of the organic peroxide in a module bonding process in which the lower substrate protective material is stacked on top and bottom of the intermediate layer filling adhesive sheet. How to bond with materials. 13 Organosilane compound as a coupling agent,
13. The bonding method according to claim 12, wherein an organic silane peroxide or an organic titanate compound is used. 14. The bonding method according to claim 12, wherein an organic peroxide having a decomposition temperature of about 90 to 190°C is used. 15 Ethylene-vinyl acetate copolymer resin with a vinyl acetate content of about 20 to 40% by weight is used as an ethylene-based copolymer resin to be formed into a filling adhesive sheet to be bonded onto the solar cell element formed on the upper surface of the lower substrate protection material. 13. The bonding method according to claim 12, wherein coalescence is used. 16 Ethylene-vinyl acetate copolymer with a vinyl acetate content of about 40% by weight or less as an ethylene-based copolymer resin molded into a filling adhesive sheet to be bonded under the solar cell element formed on the lower surface of the upper transparent protective material. 13. The bonding method according to claim 12, wherein: