JPS629232B2 - - 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 there has been a need to develop alternative energy sources.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 made of silicon semiconductors have a small electromotive force, and therefore a useful voltage can be obtained by connecting wafers in series or parallel, so the connecting material must not corrode and have a 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.
This had drawbacks such as being expensive, requiring long coating and bonding steps, and being unsuitable for automation. For this reason, sheets of polyvinyl butyral resin, which has a proven track record in 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 increases in this copolymer, transparency and flexibility improve, but sheet formability and
Blocking properties deteriorate, making it difficult to satisfy both properties at the same time.
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.

By the way, in the bonding process for modularization, glass or the like is also used as an external protective material, so sufficient consideration must be given to heating.
That is, rapid temperature changes may damage these materials. For this reason, there is a strong need for a filling adhesive that shortens the bonding time, automates the bonding process, and does not degrade the working environment. It has now been found that sheets formed from coalescing and organic peroxides are well suited for such purposes, and the present invention has now been completed.

Accordingly, the present invention relates to a filled adhesive sheet for solar cells, which is comprised of a mixture of a silane-modified ethylene copolymer 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 a material made of a silane-modified ethylene copolymer and an organic peroxide. Both are sandwiched between two filled adhesive sheets, and an upper transparent protective material and a lower substrate protective material are layered on both sides, or a filled adhesive sheet formed from a silane-modified ethylene copolymer and an organic peroxide. is used as an intermediate layer, and an upper transparent protective material and a lower substrate protective material in which a solar cell element is formed on the inward surface of one of the protective materials are stacked on top and bottom of the intermediate layer filling adhesive sheet. This is carried out by heating the organic peroxide to a temperature higher than its decomposition temperature during the combining process.

The ethylene copolymer used for silane modification has a light transmittance of about 80% or more, preferably about 80% or more.
Suitable copolymers are those having an elastic modulus of 90% or more and an elastic modulus of about 1 to 30 MPa, preferably about 3 to 12 MPa. 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 A terpolymer or a metal salt thereof (ionomer resin) is used.

Among these ethylene-based copolymers, the most preferred 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, increasing the risk of damage to the power generation element due to thermal expansion and contraction. 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.

Silane modification of these ethylene copolymers is
The reaction is carried out by heating with a silane compound, preferably in the presence of a free radical producing compound such as an organic peroxide, generally at a temperature of about 140° C. or higher. The silane compound used as a modifier has the general formula RR′SiY ₂ (where R is a monovalent unsaturated hydrocarbon group or hydrocarbonoxy group, Y is a hydrolyzable organic group, and
R' is the same group as R or Y above), and typical examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, etc. The compounds are also well known to those skilled in the art.

During this reaction, some of the silane modifier may remain unreacted, but this unreacted compound is
When a silane-modified ethylene copolymer is molded into a sheet, it becomes a source of odor, but does not pose any quality problem. If necessary, this unreacted compound can be removed in advance by a well-known technique using a vented extruder or the like. Although the content of silane groups in the modified resin is not particularly limited,
Generally about 0.1 to 10% by weight, preferably about 0.3 to 10% by weight from the viewpoint of crosslinking reactivity, adhesiveness, economic efficiency, etc.
It is in the range of 3% by weight. As described below, when the modified resin is used as a blend of a silane-modified ethylene copolymer and an unmodified ethylene copolymer, this range of silane group content relative to the total weight of both is generally used. It will be done.

Such a silane-modified ethylene copolymer exhibits good adhesiveness when bonded to an external protective material by heating. For example, when adhering to an external protective material such as glass or polyvinyl fluoride, a sheet containing only unmodified ethylene copolymer as a resin component does not provide sufficient adhesion for practical purposes, and a primer is applied to the surface of the external protective material. Although it is essential to apply a silane-modified version of it, good adhesion can be obtained with the external protective material that is not coated with a primer. Furthermore, since primer application is not required, there is no evaporation of organic solvents associated with it, and a good working environment can be maintained during the bonding process. On the other hand, when the ethylene copolymer is simply mixed with a silane compound without silane modification, not only is there almost no effect of promoting crosslinking due to the coexistence of the silane compound (comparison below) (See Examples 3 and 5), migration and evaporation of some of the silane compounds are observed, and as a result, non-uniform concentration of the silane compounds and deterioration of the bonding work environment are unavoidable.

In addition, a part of the silane-modified ethylene copolymer may be added within a range that does not impede the purpose of the present invention.
It can be substituted with an unmodified ethylene copolymer and used as a blend. The unmodified ethylene copolymer used preferably has a chemical structure that is the same as or close to that of the silane-modified ethylene copolymer blended with it before silane modification, and generally has a lower vinyl acetate content. Ethylene-vinyl acetate copolymer having about 20 to 40% by weight is used. Further, it is preferable to use these ethylene copolymers (referring to silane-modified and unmodified ethylene copolymers) having the same melt fluidity. This is because these similarities in chemical structure and melt flowability affect melt-kneading properties during sheet molding, as well as optical properties and adhesive properties after lamination. Generally, the unmodified ethylene copolymer is blended in a proportion of about 500 parts by weight or less per 100 parts by weight of the silane-modified ethylene copolymer.

When these silane-modified ethylene copolymers are heated in the presence of an organic peroxide, their crosslinking time is significantly shortened. This indicates that the time required for the bonding process is shortened, resulting in a cost reduction, which is an important effect. Furthermore, although it is well known that silane-modified ethylene copolymers are generally crosslinked using a silanol condensation catalyst, the crosslinking time can be significantly shortened by using an organic peroxide without using such a condensation catalyst. Also,
Characteristics of the present invention can be seen. Note that a silanol condensation catalyst and an organic peroxide can also be used together, and in this case, water resistance etc. are further improved.

The organic peroxide that crosslinks the silane-modified ethylene copolymer is decomposed by heating to generate radicals, and the organic peroxide that crosslinks the silane-modified ethylene copolymer and the unmodified ethylene copolymer used together as necessary. It has the function of generating radicals in the ethylene-based copolymer and crosslinking it, and it does not substantially decompose at the molding temperature when sheet-forming with an extruder and the time it is maintained at this temperature, and furthermore, it can be made into modules. In the process, a material that decomposes quickly at a temperature below the decomposition temperature of the ethylene copolymer is used. Generally about 90~190℃, preferably about 120~
Decomposition temperature of 160℃ (temperature at which the half-life is 1 hour)
The one with the following is used.

Examples of such organic peroxides include tert-butyl peroxyisopropyl carbonate, tert-butyl peroxy acetate, tert-butyl peroxy benzoate, dicumyl peroxide, 2,
5-dimethyl-2,5-bis(tert-butylperoxy)hexane, di-tert-butyl peroxide,
2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyne-3,1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis( 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, hydroxyhebutyl peroxide, cyclohexanone peroxide, etc. Can be mentioned.

In these organic peroxides, the silane-modified or unmodified ethylene copolymer is crosslinked when heated during the solar cell module bonding process, improving heat resistance and contributing to improved adhesion. It is added only in the required amount. 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 total amount of ethylene copolymer. If the addition ratio is less than this, the transparency and heat resistance of the module and the adhesion between the filling adhesive and the external protective materials will not be sufficient.

If 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, 2-(2'-hydroxy-5-tertiary octylphenyl)benzotriliazole, salicylic acid ester types such as phenyl salicylate and p-octylphenyl salicylate, and nickel complex salts. system,
Hindered amine type stabilizers 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, the organic peroxide, and the light stabilizer added as necessary are dry-blended in advance and fed from the hopper of the extruder, and the mixture is heated at a molding temperature at which the organic peroxide does not substantially decompose. Shaping is carried out by extrusion into a sheet, preferably through an embossed take-up roll. The formation of arbitrary embossed patterns is
It is effective in preventing sheet blocking and degassing during the solar cell modularization process. The thickness of the sheet is not particularly specified, but it is generally approximately 0.1
It is about ~1 mm.

In addition, if the organic peroxide is in the form of a solution or used as a solution, the solvent may be removed in advance to prepare pellets using a well-known extruder with a vent function, and then the above steps may be performed. Alternatively, a method may be adopted in which a T-die is installed directly at the tip of an extruder having a vent function, and the solvent is removed by the vent device to form sheets at once.

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, a surfactant solution or organic This is done by laminating protective materials that have been cleaned with a solvent or surface treated with corona discharge, chemicals, etc., that is, an upper transparent protective material and a lower substrate protective material, and then heat-bonded them under vacuum. . 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 containing an organic peroxide, and then bonded to the upper transparent protective material and the lower substrate protective material. It is desirable that the heating be carried out until the organic peroxide added to the filled adhesive sheet is completely decomposed. Through this heat treatment, the filling adhesive and each external protective material are firmly adhered, and the solar cell element is laminated with the two filling adhesive sheets, which are also attached to the upper transparent protective material and the lower substrate protective material. A solar cell module is formed there, which is firmly bonded to the material.

In addition, solar cell elements are made of glass, plastic,
If the solar cell element is formed on a protective material such as ceramic or stainless steel, a filled adhesive sheet is used as an intermediate layer, and the 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 upper 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% by weight, melt index 15g/10min) 100
2.0 parts of vinyltrimethoxysilane and 0.2 parts of di-tert-butyl peroxide were added to 1.0 parts of vinyltrimethoxysilane and 0.2 parts of di-tert-butyl peroxide, and extruded from a vented extruder at 200°C to obtain a silane-modified ethylene-vinyl acetate copolymer (melt index: 9 g/ 10 minutes at 190°C). When undecomposed di-tert-butyl peroxide in this modified copolymer was extracted with methanol and analyzed by gas chromatography, the content was found to be
It was 0.1% by weight or less. Furthermore, when the silane groups in the resin were measured by ashing analysis, the content was 1.5% by weight.

This silane-modified ethylene-vinyl acetate copolymer
100 parts, 1.5 parts of di-tert-butyl peroxide, 2-
Hydroxy-4-n-octylbenzophenone
0.3 part and tetrakis-[methylene-3-
(3′,5′-di-tert-butyl-4-hydroxyphenyl)propionate] A mixture prepared by dry blending 0.1 part of methane in advance was extruded into a sheet at a resin temperature of 95°C using a T-die extruder. An embossed sheet with a thickness of 0.5 mm was formed by applying an embossed pattern to both sides of the sheet using a take-up roll with an embossed pattern.

The solar cells were modularized as follows.

Clean the surface with a neutral detergent aqueous solution, then rinse it with distilled water, and air dry it.
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, a product of DuPont, USA)
400BS30WH) and melted and bonded them using a vacuum laminator at a heating temperature of 110°C, and further heated at 150°C for 30 minutes to decompose the organic peroxide and form silane-modified ethylene.
A module was created by crosslinking the vinyl acetate copolymer and at the same time firmly adhering it to an 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.

Following these modularization conditions, the embossed sheet was heated in a 150℃ heating furnace for a specified period of time, and the JISC
When the degree of crosslinking was measured using a method compliant with -8005, the following values were obtained.

Table 1 Heating time (minutes) Degree of crosslinking (%) 0 0 1.0 21 2.0 55 3.0 65 4.5 70 A white plate glass-embossed sheet-polyfluorinated vinyl sheet laminate was prepared according to the above-mentioned module lamination method. The peel strength of the material was measured using a tensile tester at a tensile speed of 20 cm/min and a temperature of 23°C.
The embossed sheet was measured by T-peeling under conditions of 60% relative humidity, and the average value of 5 samples was calculated.
cm, and 1.4 for polyvinyl vinyl sheets
It exhibited a good peel strength of Kgf/cm.

Similarly, a white glass-embossed sheet white glass laminate was produced, and for this laminate,
When the light transmittance at a wavelength of 500 mμ was measured using a UV meter, a good value of 87% was obtained. Furthermore, this laminate was continuously irradiated with ultraviolet rays for 100 hours using an ultraviolet irradiator, and its external rays were observed, and it was found to be good.

Additionally, the module was subjected to temperature and humidity cycling tests. In the temperature cycle test, after performing 20 cycles of 4 hours each at high temperature (+90°C) and low temperature (-40°C), the appearance of the module was observed and no abnormality was found. It also has a humidity cycle at a temperature of 40
After 5 cycles of 16 hours and 4 hours each at 90% relative humidity or higher at 23°C and 90% or higher relative humidity at 23°C, the appearance of the module was observed and no abnormalities were found.

The above results indicate that the sheet used in the present invention is extremely useful as a filling adhesive sheet for solar cells.

Example 2 Other ethylene-vinyl acetate copolymer (Mitsui Polychemical product Evaflex #150, vinyl acetate content 33% by weight, melt index 30g/10 minutes)
Using 100 parts, a silane-modified ethylene-vinyl acetate copolymer (melt index: 6 g/10 minutes) was produced in the same manner as in Example 1. The amount of undecomposed di-tert-butyl peroxide in this modified copolymer is 0.1% by weight or less, and the content of silane groups in the resin is
It was 1.5%.

This silane-modified ethylene-vinyl acetate copolymer
100 parts, 2,5-dimethyl-2,5-bis (3rd
butylperoxy)hexane 1.5 parts, 2-hydroxy-4-n-octylbenzophenone 0.3
, bis(2,2,6,6-tetramethyl-4-
An embossed sheet with a thickness of 0.5 mm was molded in the same manner as in Example 1 using a dry-blended mixture of 0.1 part of piperidine) sebacate and 0.2 part of tris(mixed mono-dinonylphenyl) phosphite.

Using this embossed sheet, a module was produced in the same manner as in Example 1, and the degree of crosslinking thereof was measured, and the following values were obtained.

Table 2 Heating time (minutes) Degree of crosslinking (%) 0 0 1.0 20 2.0 56 3.0 67 4.5 72 A white plate glass-embossed sheet-polyfluorinated vinyl sheet laminate was prepared according to the lamination method for modularization, and its peel strength was measured. When measured, the peel strength was 3.7 Kgf/cm against the embossed white glass sheet and 1.5 Kgf/cm against the polyfluorinated vinyl sheet.

Similarly, white plate glass - embossed sheet -
A white glass laminate was prepared and its light transmittance was measured and a good value of 91% was obtained. Further, this laminate was continuously irradiated with ultraviolet rays for 100 hours, and its appearance remained good.

Example 3 In Example 1, 50 parts of 100 parts of the silane-modified ethylene-vinyl acetate copolymer was replaced with the unmodified ethylene-vinyl acetate copolymer, and an embossed sheet with a thickness of 0.5 mm was made from the blend. was molded.

Using this embossed sheet, a module was produced in the same manner as in Example 1, and the degree of crosslinking thereof was measured, and the following values were obtained.

Table 3 Heating time (minutes) Degree of crosslinking (%) 0 0 1.0 10 2.0 30 3.0 42 4.5 54 A white glass-embossed sheet-polyfluorinated vinyl sheet laminate was prepared according to the lamination method for modularization, and its peel strength was measured. When measured, the embossed sheet showed good peel strength of 3.3 kgf/cm against white plate glass and 1.3 kgf/cm against polyfluorinated vinyl sheet.

Similarly, white plate glass - embossed sheet -
A white plate glass laminate was prepared and its light transmittance was measured and a good value of 87% was obtained. Further, this laminate was continuously irradiated with ultraviolet rays for 100 hours, and its appearance remained good.

Comparative Example 1 In Example 1, using another ethylene-vinyl acetate copolymer (Mitsui Polychemical product EVAFLEX #550, vinyl acetate content 14% by weight, melt index 15 g/10 minutes), silane-modified ethylene-vinyl acetic acid copolymer was prepared. A vinyl copolymer was produced and an embossed sheet was formed from it.

Using this embossed sheet, a white plate glass-embossed sheet-white plate glass laminate was produced, and when its light transmittance was measured, a value of only 72% was obtained.

Comparative Example 2 In Example 1, using another ethylene-vinyl acetate copolymer (Mitsui Polychemical product Evaflex #45X, vinyl acetate content 45% by weight, melt index 80 g/10 minutes), silane-modified ethylene-vinyl acetate copolymer was prepared. A vinyl copolymer was produced. Then, sheet molding was carried out in the same manner as in Example 1, but the adhesive to the take-up roll was significant and a satisfactory embossed sheet could not be obtained.

Comparative Example 3 In Example 1, an embossed sheet was molded using an unmodified ethylene-vinyl acetate copolymer instead of the silane modified product, and the degree of crosslinking was measured, and the following values were obtained.

Table 4 Heating time (minutes) Degree of crosslinking (%) 0 0 1.0 0 2.0 6 3.0 8 4.5 26 Also, using this embossed sheet, a white plate glass-embossed sheet-polyfluorinated vinyl sheet laminate was prepared, and this was peeled off. When measuring the strength, the embossed sheet has a strength of 0.1Kgf/cm compared to white glass.
Also, 0.4Kgf/cm for polycarbonate vinyl sheet
It only showed the value of .

Comparative Example 4 In Example 1, an embossed sheet was formed using only the silane-modified ethylene-vinyl acetate copolymer without adding any organic peroxide or light stabilizer, and the degree of crosslinking was measured. Even after 45 minutes, the value was still 0.

Comparative Example 5 In Comparative Example 3, 2.0 parts of vinyltrimethoxysilane was further added to form an embossed sheet, and the degree of crosslinking was measured, and the following values were obtained.

Table 5 Heating time (minutes) Crosslinking degree (%) 0 0 1.0 0 2.0 6 3.0 10 4.5 33 Example 4 The embossed sheet obtained in Example 2 and the solar cell element formed on the white glass substrate were placed on top of the solar cell element formed on the white glass substrate. The polyfluorinated vinyl sheets were layered one after another, and the module was bonded in the same manner as in Example 1.

The obtained solar cell module was subjected to a temperature cycle test and a humidity cycle test in the same manner as in Example 1. 20 in temperature cycle test
When the appearance of the module was observed after 5 cycles and humidity cycles, no abnormality was found in either case.

Claims (1)

[Claims] 1. A filled adhesive sheet for solar cells comprising a mixture of a silane-modified ethylene copolymer and an organic peroxide. 2. The filled adhesive sheet according to claim 1, wherein the silane-modified ethylene copolymer is a silane-modified ethylene-vinyl acetate copolymer having a vinyl acetate content of about 40% by weight or less. 3. The filled adhesive sheet according to claim 1, wherein the silane-modified ethylene copolymer is a silane-modified ethylene-vinyl acetate copolymer having a vinyl acetate content of about 20 to 40% by weight. 4. The filled adhesive sheet according to claim 1, 2 or 3, in which a silane-modified ethylene copolymer containing about 0.1 to 10% by weight of silane groups is used. 5. The filled adhesive sheet according to claim 1, wherein an organic peroxide having a decomposition temperature of about 90 to 190°C is used. 6 A solar cell element is sandwiched between at least two filled adhesive sheets made of a silane-modified ethylene copolymer and an organic peroxide, and an upper transparent protective material and a lower substrate protective material are layered on both sides. 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. 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 vinyl acetate content of the silane-modified ethylene copolymer molded into the filled adhesive sheet is approximately 20 to
7. The bonding method according to claim 6, wherein 40% by weight of a silane-modified ethylene-vinyl acetate copolymer is used. 9. The bonding method according to claim 6 or 8, wherein a silane-modified ethylene copolymer containing about 0.1 to 10% by weight of silane groups is used. 10. 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. 11 Claim 6, in which the silane-modified ethylene copolymer molded into the filled adhesive sheet is blended with an unmodified ethylene copolymer.
Adhesion method described in section. 12. The bonding method according to claim 11, wherein the unmodified ethylene copolymer is an ethylene-vinyl acetate copolymer having a vinyl acetate content of about 20 to 40% by weight. 13. The bonding method according to claim 6, wherein an organic peroxide having a decomposition temperature of about 90 to 190°C is used. 14 Upper transparent protective material and lower substrate protection in which a filled adhesive sheet made of a silane-modified ethylene copolymer and an organic peroxide is used as an intermediate layer, and a solar cell element is formed on the inward surface of one of the protective materials. In the module bonding process in which the materials are stacked on top and bottom of the intermediate layer filling adhesive sheet,
A method for adhering a solar cell protective material and a filler, the method comprising heating to a temperature higher than the decomposition temperature of the organic peroxide. 15 Ethylene-vinyl acetate copolymer with a vinyl acetate content of about 20 to 40% by weight is used as a silane-modified ethylene-based copolymer 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. 15. The bonding method according to claim 14, wherein a silane-modified polymer is used. 16 Ethylene-vinyl acetate copolymer with a vinyl acetate content of about 40% by weight or less as a silane-modified ethylene-based copolymer to be formed into a filling adhesive sheet to be bonded under the solar cell element formed on the lower surface of the upper transparent protective material. 15. The adhesion method according to claim 14, wherein a silane-modified composite is used. 17. The bonding method according to claim 14, 15 or 16, wherein a silane-modified ethylene copolymer containing about 0.1 to 10% by weight of silane groups is used. 18 Claim 1, in which the silane-modified ethylene copolymer to be molded into the filled adhesive sheet is blended with an unmodified ethylene copolymer.
The adhesion method according to item 4, item 15 or item 16. 19. The bonding method according to claim 14, wherein an organic peroxide having a decomposition temperature of about 90-190°C is used.