JP2008085015A - Method for manufacturing adhesive sheet for solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an adhesive sheet for a solar cell. <P>SOLUTION: The method for manufacturing the adhesive sheet for the solar cell of this invention comprises the steps of supplying a first resin composition including the organic peroxide and mainly composed of an ethylene series copolymer to an extruder and melting/kneading to extrude it, and meanwhile supplying a resin composition including the organic peroxide and an antiscorching agent and mainly composed of the ethylene series copolymer with its cross-linking property lower than that of the first resin composition, or a resin composition including no organic peroxide and mainly composed of the ethylene copolymer without having the cross-linking property to an extruder different from the above extruder and melting/kneading to extrude it. The first resin composition and the second resin composition are flowed together, and the adhesive sheet for the solar cell comprising an intermediate sheet layer composed of the first resin composition and an outside sheet layer for covering the intermediate sheet layer and composed of the second resin composition is extruded together. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a solar cell adhesive sheet that is preferably used to join a solar cell element and a protective material when a solar cell module is produced.

  A solar cell module consisting of a silicon or selenium semiconductor wafer is under reduced pressure on a laminate obtained by overlaying an upper transparent protective material on the upper surface of a solar cell element with adhesive sheets laminated on both sides and a lower substrate protective material on the lower surface. It is manufactured by heating while deaeration and laminating and integrating a protective material on the upper and lower surfaces of the solar cell element via an adhesive sheet.

  As an adhesive sheet for solar cells used in such a solar cell module, for example, Patent Document 1 discloses a main body layer (A) mainly composed of an ethylene-vinyl acetate copolymer and a (meth) acrylic ester content. Proposed is a cross-linkable laminated sheet having a thickness of 0.2 to 1.2 mm, comprising a sealing layer (B) mainly composed of 15 to 35% by weight of an ethylene- (meth) acrylate copolymer. Patent Document 2 discloses that a main body layer (A) mainly composed of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 21 to 40% by weight and a vinyl acetate content of 10% by weight or more and less than 21% by weight. A crosslinkable laminated sheet having a thickness of 0.2 to 1.2 mm composed of a sealing layer (B) mainly composed of an ethylene-vinyl acetate copolymer has been proposed.

  And as a film forming method of the crosslinkable laminated sheet described in Patent Documents 1 and 2, an ethylene-vinyl acetate copolymer or an ethylene- (meth) acrylate copolymer is a main component in two extruders. A resin composition comprising a resin, a crosslinking agent such as an organic peroxide, and additives such as a crosslinking aid and a silane coupling agent added as necessary, and melt-kneaded at 120 ° C. Thereafter, a method of extruding a two-layer crosslinkable laminated sheet from a multilayer T die is disclosed.

  However, when the crosslinkable laminated sheet is formed as described above, the temperature of the inner surface of the T die is high, so that the resin composition developed in a sheet shape in the T die is heated to the inner surface of the T die. The crosslinking agent is decomposed, and the crosslinking of the resin proceeds. Therefore, the melt viscosity of the resin composition is increased, and the resin composition stays in the T die, resulting in a problem that a sheet having a uniform thickness cannot be obtained. In addition, if the resin composition stays in the T die, the contact time between the resin composition developed in the form of a sheet and the inner surface of the T die becomes longer, and the crosslinking of the resin further proceeds. There was also a situation in which the sheet could not be extruded due to solidification.

JP 2005-129925 A JP 2005-129926 A

  In view of the above-mentioned problems, the present invention provides a method for producing an adhesive sheet for a solar cell, in which an ethylene copolymer can be stably formed into a uniform thickness without staying or solidifying in a T-die. To do.

  The method for producing an adhesive sheet for solar cells of the present invention is to supply a first resin composition containing an organic peroxide and having an ethylene copolymer as a main component to an extruder, melt knead and extrude, A resin composition containing an organic peroxide and a scorch inhibitor and having an ethylene copolymer as a main component and having a crosslinkability lower than that of the first resin composition, in an extruder different from the extruder, or A resin composition not containing an organic peroxide and having an ethylene copolymer as a main component and having no crosslinkability is supplied as a second resin composition, melted and kneaded, and extruded. The resin composition is merged, and the sheet-shaped second resin composition is laminated and integrated on the front and back surfaces of the sheet-shaped first resin composition, and opposite ends in the width direction of the second resin composition. After joining the parts together to make a laminated sheet, Supply to a T-die to which an extruder is connected, expand the laminated sheet in the width direction in the T-die, cover the intermediate sheet layer made of the first resin composition, and the intermediate sheet layer; A solar cell adhesive sheet comprising an outer sheet layer made of the second resin composition is coextruded.

  The ethylene-based copolymer that is the main component of the first and second resin compositions is a copolymer of ethylene and a copolymerizable monomer that can be copolymerized with ethylene, and as such a copolymerizable monomer, Is not particularly limited, and examples thereof include vinyl acetate, acrylic acid, acrylic ester, methacrylic acid, methacrylic ester, maleic acid, maleic anhydride, maleic ester and the like, and vinyl acetate is preferable. In addition, the said copolymerizable monomer may be copolymerized with ethylene independently, or 2 or more types may be copolymerized with ethylene.

  On the other hand, if the amount of the copolymerizable monomer contained in the ethylene-based copolymer is small, the resulting solar cell adhesive sheet may have insufficient transparency, and the power generation efficiency of the solar cell element may be reduced. If the amount is too large, the film-forming stability and mechanical strength of the adhesive sheet for solar cells may be insufficient, so 5 to 50% by weight is preferable.

  When the melt flow rate of the ethylene copolymer is small, the film-forming stability of the solar cell adhesive sheet may be reduced, whereas when the melt flow rate is large, the mechanical strength of the solar cell adhesive sheet is insufficient. 1 to 100 g / 10 min is preferable. The melt flow rate of the ethylene copolymer in the present invention refers to a value measured under conditions of a temperature of 190 ° C. and a load of 2.16 kgf (21.18 N) according to JIS K7210.

  While the 1st resin composition has crosslinkability by containing an organic peroxide, the 2nd resin composition contains or does not contain an organic peroxide, and is more than the 1st resin composition. It has low crosslinkability or no crosslinkability. In addition, when not giving crosslinkability to the 2nd resin composition, what is necessary is just not to contain the organic peroxide mentioned later. Next, the case where both the first and second resin compositions have crosslinkability will be described.

  Both the first and second resin compositions contain an organic peroxide. Examples of such organic peroxides include dicumyl peroxide (136 ° C.), t-butyl peroxy-2-ethylhexyl monocarbonate (119 ° C.), t-butyl peroxybenzoate (125 ° C.), 1, 1-bis (t-butylperoxy) -2-methylcyclohexane (102 ° C.), 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane (106 ° C.), 1,1- Bis (t-hexylperoxy) cyclohexane (107 ° C.), 1,1-bis (t-butylperoxy) cyclohexane (111 ° C.), 2,2-bis (4,4-bis (t-butylperoxy) Cyclohexyl) propane (114 ° C.), t-hexylperoxyisopropyl monocarbonate (115 ° C.), t-butylperoxyisopropyl Pyrmonocarbonate (118 ° C.), t-butyl peroxylaurate (118 ° C.), 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane (119 ° C.), t-hexyl peroxybenzoate (119 ° C), t-butylperoxymaleic acid (119 ° C), t-butylperoxy-3,5,5-trimethylhexanoate (119 ° C), t-butylperoxyacetate (121 ° C), 2,2 -Bis (t-butylperoxy) butane (122 ° C), n-butyl-4,4-bis (t-butylperoxy) valerate (127 ° C), di-t-hexyl peroxide (136 ° C), t -Butylcumyl peroxide (137 ° C), bis (2-t-butylperoxyisopropyl) benzene (138 ° C), 2,5-dimethyl-2 5-bis (t-butylperoxy) hexane (138 ° C.), di-t-butyl peroxide (144 ° C.), 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3 ( 150 ° C.), p-menthane hydroperoxide (151 ° C.) and the like, and may be used alone or in combination of two or more. The temperature in the parenthesis represents a 1 hour half-life temperature.

  In addition, if the content of the organic peroxide contained in the first resin composition is small, the crosslinking of the ethylene copolymer becomes insufficient during the production of the solar cell module, and the gel fraction is reduced. In some cases, the durability of the resulting solar cell module may be reduced due to insufficient heat resistance of the solar cell adhesive sheet. Along with the decomposition of the oxide, a large amount of low molecular weight compounds such as acetone and carbon dioxide are generated, causing bubble expansion between the facing surfaces of the solar cell element and the protective material, and the adhesion between the solar cell element and the protective material. Decreases, the protective function of the solar cell element decreases, or the solar cell adhesive sheet may be discolored and the power generation efficiency of the solar cell element may decrease, so that the ethylene copolymer 100 parts by weight 0.1 to 3 layers Parts and more preferably 0.3 to 1.5 parts by weight.

  And when there is little content of the organic peroxide contained in a 2nd resin composition, at the time of manufacture of a solar cell module, bridge | crosslinking of an ethylene-type copolymer becomes inadequate, and it adheres for solar cells. While the heat resistance of the sheet is insufficient and the durability of the resulting solar cell module may be reduced, in many cases, when the adhesive sheet for solar cells is formed, the ethylene-based copolymer is cross-linked and the inside of the T-die It becomes impossible to obtain a solar cell adhesive sheet having a uniform thickness, or the ethylene copolymer is solidified in the T-die and the solar cell adhesive sheet cannot be extruded. Therefore, 0.01 to 0.6 parts by weight is preferable with respect to 100 parts by weight of the ethylene copolymer.

  While the first resin composition has crosslinkability, the second resin composition has lower crosslinkability than the first resin composition or does not have crosslinkability. Thus, in order to make the crosslinkability of the first resin composition higher than that of the second resin composition, only the second resin composition contains a scorch inhibitor, or in the first and second resin compositions. When the scorch inhibitor is contained in the second resin composition, the second resin composition contains a greater amount of scorch inhibitor than the content of the scorch inhibitor in the first resin composition.

  The scorch inhibitor is not particularly limited and is 2,4-diphenyl-4-methyl-1-pentene, 2,6-di-t-butyl-p-cresol, hydroquinone, 2-mercaptobenzothiazole, octyl methacrylate. N-nitrosodiphenylamine and the like may be used alone or in combination of two or more.

  If the amount of the scorch inhibitor contained in the second resin composition is small, the ethylene copolymer is crosslinked and stays in the T-die when the adhesive sheet for solar cells is formed. On the other hand, it may be impossible to obtain a solar cell adhesive sheet with a small thickness, or the ethylene-based copolymer may solidify in a T-die and the solar cell adhesive sheet cannot be extruded. When the solar cell module is manufactured, the ethylene copolymer is not sufficiently cross-linked, the heat resistance of the solar cell adhesive sheet is insufficient, and the durability of the resulting solar cell module may be reduced. Therefore, 0.01-2 weight part is preferable with respect to 100 weight part of ethylene-type copolymers.

  Moreover, the scorch inhibitor may be added to the first resin composition as long as it does not inhibit the crosslinking of the ethylene copolymer, but it is preferable that the scorch inhibitor is not contained.

  Furthermore, the solar cell adhesive sheet of the present invention preferably has a gel fraction of the entire adhesive sheet of 70% by weight or more after the solar cell module is manufactured.

  In addition, if it is in the range which does not impair the physical property of the adhesive sheet A for solar cells in a 1st, 2nd resin composition, a crosslinking adjuvant, a coupling agent, and 2, 6-di-t as needed. Additives such as antioxidants such as -butyl-4-methylphenol and ultraviolet absorbers such as 2-hydroxy-4-methoxybenzophenone may be added.

  Examples of the crosslinking aid include polyfunctional monomers having two or more allyl groups, vinyl groups, acryloyl groups, or methacryloyl groups, which stabilize polymer radicals to increase crosslinking efficiency and concentrate crosslinking points. To promote gel formation. Examples of the polyfunctional monomer include diallyl phthalate, diallyl itaconate, diallyl maleate, triallyl isocyanurate, triallyl cyanurate, triallyl phosphate, divinylbenzene; 1,6-hexanediol di (meth) acrylate (Meth) such as ethylene oxide modified bisphenol A di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ε-caprolactone modified dipentaerythritol Examples include acrylates and alkyl-modified dipentaerythritol (meth) acrylates, which may be used alone or in combination of two or more. In addition, (meth) acrylate means a methacrylate or an acrylate.

  The coupling agent is added for the purpose of improving the adhesion of the solar cell adhesive sheet, and the coupling agent is one or more selected from the group consisting of an amino group, a glycidyl group, a methacryloxy group, and a mercapto group. A silane coupling agent having a functional group of, for example, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxy Silane etc. are mentioned, and it may be used independently or 2 or more types may be used together.

  Next, the first resin composition configured as described above is supplied to an extruder and melt-kneaded at a temperature at which the organic peroxide is not substantially decomposed, while the second resin composition is mixed with the extruder. Is supplied to another extruder and melt-kneaded at a temperature at which the organic peroxide is not substantially decomposed.

  As will be described later, since the second resin composition is laminated and integrated as a sheet on the front and back surfaces of the first resin composition formed into a sheet, two extruders for supplying the second resin composition are prepared. The second resin composition may be supplied to these extruders, or the second resin composition may be supplied to one extruder and extruded from the extruder and then branched into two. Also good.

  Moreover, when the intermediate sheet layer of the solar cell adhesive sheet to be manufactured is composed of a plurality of layers, a plurality of extruders for supplying the first resin composition are prepared, and the first resin composition is provided in each extruder. Can be supplied.

  And when the temperature at the time of melt-kneading the 1st and 2nd resin composition in an extruder is high, the organic peroxide in a resin composition will decompose | disassemble and the bridge | crosslinking of an ethylene-type copolymer will advance. Therefore, the temperature is preferably 10 ° C. or more lower than the one-hour half-life temperature of the organic peroxide used. In the case of using two or more organic peroxides, the organic peroxide used is Of these, the temperature is preferably 10 ° C. or lower than the one-hour half-life temperature of the lowest organic peroxide.

  Next, all the extruders supplied with the first and second resin compositions are connected to one multilayer T-die, and the first and second resin compositions melt-kneaded by the extruder are used as the extruder. And then branched into a plurality of parts as necessary, and then supplied to a multilayer T die through an adapter.

  Specifically, after the first and second resin compositions are extruded from the extruder, they are merged in the multi-layer T-die and formed into a sheet-like second surface on the front and back surfaces of the first resin composition. The resin composition is laminated and integrated, and the sheet-like second resin composition is protruded from both ends in the width direction of the sheet-like first resin composition, and the end of the first resin composition Both end portions of the second resin composition that face each other and protrude from each other are merged and integrated to form a laminated sheet. The laminated sheet is in a state in which the first resin composition is entirely covered with the second resin composition over the entire circumference in a cross section in a direction perpendicular to the extrusion direction. The end surfaces in the width direction of the first resin composition as well as the front and back surfaces of the one resin composition are completely covered with the second resin composition. When the first resin composition is extruded from a plurality of extruders, the sheet-like first resin composition is formed in a plurality of layers.

  The laminated sheet formed as described above is continuously supplied into the T-die and expanded in the width direction, and then extruded from the T-die. The molten sheet is cooled with a cooling roll, solidified, and wound up. Thereby, the adhesive sheet A for solar cells can be obtained.

  The obtained solar cell adhesive sheet A has an intermediate sheet layer B made of the first resin composition as shown in FIG. 1 and the intermediate sheet layer B in the circumferential direction (direction orthogonal to the extrusion direction). It consists of an outer sheet layer C that covers the entire surface and is made of the second resin composition. When the sheet-like first resin composition is formed in a plurality of layers, as shown in FIG. 2, the intermediate sheet layer B is formed from a plurality of sheet layers B1, B2,. ing.

  Here, the solar cell adhesive sheet is used by interposing between the upper transparent protective material and the lower substrate protective material and the solar cell element during the production of the solar cell module, and the solar cell is subjected to thermocompression bonding under reduced pressure. The element and the upper / lower protective material are bonded. The ethylene-based copolymer is excellent in transparency and adhesiveness among transparency, adhesiveness and heat resistance particularly required for an adhesive sheet for solar cells, but has low heat resistance, and is a solar cell module. As described above, an organic peroxide is added to the first resin composition and an organic is added to the second resin composition as necessary. A peroxide is contained, and the ethylene copolymer is crosslinked by heat applied during the production of the solar cell module, thereby improving the heat resistance of the adhesive sheet for solar cells.

  However, in the manufacturing process of the solar cell adhesive sheet as described above, if the ethylene copolymer is cross-linked, the ethylene copolymer stays in the T-die and has a uniform thickness. Cannot be obtained, or the ethylene copolymer is solidified in the T-die and a solar cell adhesive sheet cannot be produced.

  Then, in the manufacturing method of the adhesive sheet for solar cells of this invention, the outer peripheral surface of a lamination sheet which is easy to bridge | crosslink in direct contact with the T-die inner surface which is high temperature, crosslinkability of the whole adhesive sheet for solar cells obtained Is formed from the second resin composition having low crosslinkability or no crosslinkability within the range that does not impair the property, and prevents or suppresses the crosslinking of the ethylene-based copolymer during the production of the solar cell adhesive sheet. The production stability of the adhesive sheet for use is not impaired.

  Then, in the obtained solar cell adhesive sheet A, the intermediate sheet layer B and the outer sheet layer C are laminated and integrated in the thickness direction of the solar cell adhesive sheet A, in the thickness direction of the solar cell adhesive sheet. When the total thickness of the outer sheet layer C is too large, crosslinking of the ethylene copolymer is insufficient during the production of the solar cell module, and the heat resistance of the adhesive sheet for solar cells is insufficient. Since the durability of the module is reduced, it is preferably 30% or less of the total thickness of the solar cell adhesive sheet A. However, if the thickness is too thin, the solar cell adhesive sheet is formed in the intermediate sheet layer B at the time of film formation. The ethylene copolymer crosslinks and stays in the T die, and a uniform thickness solar cell adhesive sheet cannot be obtained, or the ethylene copolymer does not remain in the T die. And the solar cell adhesive sheet may not be extruded, so the lower limit of the sum of the thicknesses of the outermost sheet layers C of the solar cell adhesive sheet A is the thickness of the entire solar cell adhesive sheet A. It is preferably 5%.

  Further, the solar cell adhesive sheet A is preferably embossed on the surface in order to improve the deaeration in the thermocompression bonding step when the solar cell module is manufactured. In addition, as a method of embossing the surface of the adhesive sheet A for solar cells, a known method is used. For example, the adhesive sheet A for solar cells in a molten state immediately after being extruded from a T die is embossed on the surface. The embossing roll on which the pattern is applied and the rubber roll arranged opposite to the embossing roll are supplied, and the embossing roll is pressed against the molten sheet to emboss the surface of the adhesive sheet A for solar cells. The method of giving is mentioned. The once produced solar cell adhesive sheet A may be heated again to a molten state and embossed as described above.

  And as a method of manufacturing a solar cell module using the adhesive sheet A for solar cells of this invention, first, the outer sheet | seat layer formed in the both ends of the width direction in the adhesive sheet A for solar cells first as needed. As shown in FIG. 3, the C portion is cut out so that both end portions in the width direction of the intermediate sheet layer B are exposed.

  Thus, the solar cell element is bonded to the upper transparent protective material and the lower substrate protective material by cutting off the outer sheet layer C portions formed at both ends in the width direction of the solar cell adhesive sheet A. The portion of the solar cell adhesive sheet A having a low or non-crosslinked portion is prevented from being located on the outer peripheral edge of the portion, and the solar cell element, the upper transparent protective material, and the lower substrate protective material are bonded to each other. Separation from the outer peripheral edge of the portion can be prevented, and the durability of the solar cell module can be improved by reliably bonding and integrating the two.

  Then, the upper transparent protective material is laminated on the upper surface of the solar cell element via the solar cell adhesive sheet A, and the lower substrate protective material is laminated on the lower surface of the solar cell element via the solar cell adhesive sheet A. The solar cell module in which the protective material is laminated and integrated on the upper and lower surfaces of the solar cell element via the solar cell adhesive sheet A can be obtained by producing the body and thermocompression bonding the laminated body under reduced pressure. .

  Since the manufacturing method of the adhesive sheet for solar cells of the present invention has the above-described configuration, the ethylene copolymer crosslinks and stays in the T-die when manufacturing the adhesive sheet for solar cells. Thus, the solar cell adhesive sheet having a uniform thickness can be stably produced. By using this solar cell adhesive sheet, the solar cell element and the protective material are entirely assembled. Therefore, it is possible to securely press and integrate.

  Moreover, the manufacturing method of the adhesive sheet for solar cells of this invention WHEREIN: The outer periphery of the intermediate | middle sheet layer which consists of 1st resin compositions is lower than the said 1st resin composition, or the 1st which does not have crosslinking | crosslinked property. By covering the entire surface with the outer sheet layer made of two resin compositions, the inner surface of the T-die and the intermediate sheet layer that are at a high temperature are not in direct contact with each other, and thus an adhesive sheet for a solar cell is manufactured. Since the decomposition of the organic peroxide in the intermediate sheet layer at the time is suppressed, not only a high decomposition temperature but also a low decomposition temperature are used as the organic peroxide contained in the first resin composition be able to.

  And since sufficient crosslinking | crosslinking property is provided to the intermediate sheet layer of the obtained adhesive sheet for solar cells, the heat | fever added at the time of manufacture of a solar cell module has sufficient crosslinked structure in the adhesive sheet for solar cells. It is given and heat resistance is improved. Therefore, the adhesive sheet for solar cells of the present invention reliably maintains excellent adhesion over a long period of time even when used outdoors where the temperature is high, and the resulting solar cell module has excellent durability.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Example 1)
Prepare three extruders, connect all these extruders to the three-layer feedblock T-die via adapters, and two of the three extruders to the outer sheet layer extruder, One machine was an intermediate sheet layer extruder.

  Next, an ethylene-vinyl acetate copolymer (vinyl acetate content: 27% by weight, melt flow rate: 13 g / 10 min), 100 parts by weight, t-butylperoxy-2-ethylhexyl, was added to an intermediate sheet layer extruder. 1.2 parts by weight of monocarbonate (1 hour half-life temperature: 119 ° C.), 0.02 part by weight of 2,4-diphenyl-4-methyl-1-pentene, 2,6-di-t-butyl-4-methyl A first resin composition consisting of 0.1 parts by weight of phenol and 0.3 parts by weight of 2-hydroxy-4-methoxybenzophenone is supplied and melt kneaded at 105 ° C. and extruded. For each, 100 parts by weight of ethylene-vinyl acetate copolymer (vinyl acetate content: 27% by weight, melt flow rate: 13 g / 10 min), t-butylperoxy-2-ethylhexyl 0.6 parts by weight of nocarbonate (1 hour half-life temperature: 119 ° C.), 0.08 parts by weight of 2,4-diphenyl-4-methyl-1-pentene, 2,6-di-t-butyl-4-methyl A second resin composition comprising 0.1 part by weight of phenol, 0.3 part by weight of 2-hydroxy-4-methoxybenzophenone and 0.3 part by weight of 3-glycidoxypropyltrimethoxysilane was supplied at 105 ° C. It was melt-kneaded and extruded.

  The first and second resin compositions extruded from the outer sheet layer extruder and the intermediate sheet layer extruder are both supplied to the three-layer feed block and merged, and formed into a sheet shape. The sheet-like second resin composition is laminated and integrated on the front and back surfaces of one resin composition, and both end portions in the width direction of the sheet-like second resin composition are bonded to the sheet-like first resin composition. It protruded from the both ends of the width direction, and the protrusion edge parts which oppose in this sheet-like 2nd resin composition were united and integrated, and it was set as the laminated sheet. This laminated sheet was in a state where the first resin composition was entirely covered with the second resin composition over the entire circumference in a cross section in a direction perpendicular to the extrusion direction.

  The laminated sheet is continuously supplied to a T-die maintained at 105 ° C., expanded in the width direction, extruded from the T-die, and the molten sheet is cooled with a cooling roll, solidified and wound up. Thereby, the adhesive sheet A for solar cells was obtained.

  The obtained adhesive sheet for a solar cell has an intermediate sheet layer B made of the first resin composition as shown in FIG. 1 and the intermediate sheet layer B entirely in the circumferential direction (direction perpendicular to the extrusion direction). And an outer sheet layer C made of the second resin composition.

  As shown in FIG. 3, both end portions in the width direction of the adhesive sheet for solar cells are cut by slit processing so that both end surfaces in the width direction of the intermediate sheet layer B are exposed, and the overall thickness is 900 μm and the outer side. The adhesive sheet A for solar cells whose thickness of each sheet layer C is 90 micrometers was obtained. The total thickness of the outer sheet layer C in the thickness direction of the solar cell adhesive sheet A was 20% of the total thickness of the solar cell adhesive sheet A.

  Further, in order to measure the gel fraction of the first resin composition and the second resin composition, the resulting resin composition was kneaded at 100 ° C. for 3 minutes using a lab plast mill. The gel fractions of the first and second resin compositions measured after crosslinking by heating for 20 minutes were 88% by weight and 73% by weight, respectively.

(Example 2)
In the first resin composition, instead of 1.2 parts by weight of t-butylperoxy-2-ethylhexyl monocarbonate, n-butyl-4,4-bis (t-butylperoxy) valerate (1 hour half-life temperature) 127 ° C.) 0.8 part by weight, and does not contain 2,4-diphenyl-4-methyl-1-pentene. In the second resin composition, t-butylperoxy-2-ethylhexyl monocarbonate 0 In place of 6 parts by weight, 0.6 parts by weight of n-butyl-4,4-bis (t-butylperoxy) valerate (1 hour half-life temperature: 127 ° C.) is used, and 2,4-diphenyl-4- The total thickness is 900 μm in the same manner as in Example 1 except that methyl-1-pentene is changed to 0.04 parts by weight instead of 0.08 parts by weight and the temperature of the T die is maintained at 110 ° C. Each thickness of the side sheet layer C to obtain an adhesive sheet A for solar cells is 100 [mu] m. The total thickness of the outer sheet layer C in the thickness direction of the solar cell adhesive sheet A was 22% of the total thickness of the solar cell adhesive sheet A. Moreover, the gel fraction of the single body of the 1st resin composition calculated | required similarly to Example 1 and the 2nd resin composition was 85 weight% and 72 weight%, respectively.

(Example 3)
In the first resin composition, t-butylperoxy-2-ethylhexyl monocarbonate is replaced by 1.2 parts by weight to 0.8 parts by weight, and 2,4-diphenyl-4-methyl-1-pentene In the second resin composition, except that t-butylperoxy-2-ethylhexyl monocarbonate and 2,4-diphenyl-4-methyl-1-pentene were not contained, Example 1 and In the same manner, a solar cell adhesive sheet A having an overall thickness of 800 μm and an outer sheet layer C thickness of 40 μm was obtained. The total thickness of the outer sheet layer C in the thickness direction of the solar cell adhesive sheet A was 10% of the total thickness of the solar cell adhesive sheet A. Further, the gel fractions of the first resin composition and the second resin composition obtained in the same manner as in Example 1 were 87% by weight and 0% by weight, respectively.

(Comparative Example 1)
A film-forming apparatus in which one extruder is connected to a single-layer die via an adapter is prepared, and an ethylene-vinyl acetate copolymer (vinyl acetate content: 27% by weight, Melt flow rate: 13 g / 10 min) 100 parts by weight, 1,1-bis (t-butylperoxy) cyclohexane (1 hour half-life temperature: 111 ° C.) 0.5 parts by weight, 2,6-di-t- A first resin composition comprising 0.1 part by weight of butyl-4-methylphenol and 0.3 part by weight of 2-hydroxy-4-methoxybenzophenone was supplied and melt-kneaded at 105 ° C. (1) An attempt was made to produce an adhesive sheet for a solar cell by continuously supplying a resin composition to a T-die maintained at 105 ° C. and expanding it in the width direction and then extruding it from the T-die. Immediately after starting Clogging resin composition solidifies at both end portions in the width direction of the die, it was not possible to produce an adhesive sheet for a solar cell. Moreover, the gel fraction of the single body of the 1st resin composition calculated | required similarly to Example 1 was 88 weight%.
(Comparative Example 2)
In the first resin composition, t-butylperoxy-2-ethylhexyl monocarbonate is replaced with 1.2 parts by weight to make 0.6 parts by weight, and 2,4-diphenyl-4-methyl-1-pentene In the second resin composition, t-butylperoxy-2-ethylhexyl monocarbonate is replaced by 0.4 parts by weight instead of 0.6 parts by weight, and 2,4-diphenyl-4-methyl-1 -The pentene is not contained, the temperature of the T die is maintained at 110 ° C, and the second resin composition is removed from both ends in the width direction of the first resin composition at the junction of the first and second resin compositions. The overall thickness is 650 μm and the outer sheet layer C is formed in the same manner as in Example 1 except that the first resin composition is joined with the same width dimension without projecting, and only the front and back surfaces of the first resin composition are covered. Each thickness is 75μ The adhesive sheet A for solar cells which is m was obtained. The total thickness of the outer sheet layer C in the thickness direction of the solar cell adhesive sheet A was 23% of the total thickness of the solar cell adhesive sheet A. However, the resin composition gelled at both ends in the width direction of the T-die, causing some clogging. Further, the gel fractions of the first resin composition and the second resin composition obtained in the same manner as in Example 1 were 82% by weight and 75% by weight, respectively.

(Comparative Example 3)
In the first resin composition, t-butylperoxy-2-ethylhexyl monocarbonate is replaced with 1.2 parts by weight to make 0.6 parts by weight, and 2,4-diphenyl-4-methyl-1-pentene Instead of 0.02 parts by weight, and 0.08 parts by weight. In the second resin composition, 0.04 parts by weight of 2,4-diphenyl-4-methyl-1-pentene was changed to 0.02 parts by weight. The adhesive sheet A for solar cells in which the total thickness is 800 μm and the thickness of each outer sheet layer C is 75 μm in the same manner as in Example 1 except that the weight is set to be part and the temperature of the T die is maintained at 110 ° C. Got. The total thickness of the outer sheet layer C in the thickness direction of the solar cell adhesive sheet A was 19% of the total thickness of the solar cell adhesive sheet A. However, the resin composition gelled at both ends in the width direction of the T-die, causing some clogging. Moreover, the gel fraction of the 1st resin composition and the 2nd resin composition which were calculated | required similarly to Example 1 was 73 weight% and 79 weight%, respectively.

  Table 1 shows the resin composition of these examples and comparative examples, the method and temperature of the T-die, the gel fraction of each layer alone, and the layer configuration of the sheet layer. The gel fraction, extrusion film-forming property, and appearance of the adhesive sheet for solar cells are shown in Table 1. The presence or absence of abnormalities was evaluated in the following manner, and the results are shown in Table 2.

(Gel fraction)
A solar cell adhesive sheet obtained 1 hour after the start of production of the solar cell adhesive sheet and a solar cell adhesive sheet obtained 1 hour after the production of the solar cell adhesive sheet were obtained at 150 ° C. A solar cell adhesive sheet that was crosslinked by heating for a minute was prepared. And the part (it described as "sheet edge part" in Table 2) 5 cm apart from the edge of the width direction in these adhesive sheets for solar cells to the center side along the width direction, and the center part ( In Table 2, about 0.2 g of each test piece was cut out from the “sheet center”). The exact balance value of this test piece was S (g).

Next, the test piece was immersed in 50 ml of xylene at 110 ° C. for 12 hours, the insoluble matter was filtered through a 200 mesh wire mesh, and the residue on the wire mesh was dried under reduced pressure at 80 ° C. for 4 hours to obtain a dry residue. The weight W (g) was weighed, and the gel fraction was calculated using the following formula (1). However, in Comparative Example 1, since the adhesive sheet for solar cells could not be obtained, the gel fraction could not be measured.
Gel fraction (% by weight) = 100 × W / S (1)

(Extrusion film forming property)
One hour after the start of manufacturing the solar cell adhesive sheet, the solar cell adhesive sheet extruded from the T-die was visually observed, and the extrusion film forming property was evaluated according to the following criteria.
○: A sheet having a uniform thickness was obtained.
(Triangle | delta): The sheet | seat with nonuniform thickness was extruded.
X: The resin composition was clogged in the extrusion port of T-die, and the adhesive sheet for solar cells was not able to be manufactured.

(Appearance of adhesive sheet for solar cells)
The solar cell adhesive sheet obtained 1 hour after the start of production of the solar cell adhesive sheet was visually observed for the presence or absence of abnormalities in the appearance. When x occurred, it was evaluated as x.

It is sectional drawing which showed typically the lamination | stacking state of the adhesive sheet for solar cells manufactured with the manufacturing method of the adhesive sheet for solar cells of this invention. It is sectional drawing which showed the other example which showed typically the lamination | stacking state of the adhesive sheet for solar cells manufactured with the manufacturing method of the adhesive sheet for solar cells of this invention. It is sectional drawing which shows the state which cut off the both ends of the width direction in the adhesive sheet for solar cells manufactured with the manufacturing method of the adhesive sheet for solar cells of this invention.

Explanation of symbols

A Adhesive sheet for solar cell B Intermediate sheet layer C Outer sheet layer

Claims (3)

A first resin composition containing an organic peroxide and containing an ethylene copolymer as a main component is supplied to an extruder and melt-kneaded and extruded. On the other hand, A resin composition containing an oxide and a scorch inhibitor and having an ethylene copolymer as a main component and having a crosslinking property lower than that of the first resin composition, or containing no organic peroxide and an ethylene copolymer. A resin composition having a polymer as a main component and having no crosslinkability is supplied as a second resin composition, melt-kneaded and extruded, and the first and second resin compositions are merged to form a sheet. On the front and back surfaces of 1 resin composition, the second resin composition in the form of a sheet is laminated and integrated, and both opposite ends in the width direction of the second resin composition are merged to form a laminated sheet. This laminated sheet is supplied to the T die connected to the extruder, The laminated sheet is developed in the width direction in the T die, and the solar sheet is formed of an intermediate sheet layer made of the first resin composition and an outer sheet layer covering the intermediate sheet layer and made of the second resin composition. The manufacturing method of the adhesive sheet for solar cells characterized by coextruding the adhesive sheet for batteries. The method for producing an adhesive sheet for a solar cell according to claim 1, wherein the intermediate sheet layer is entirely covered with an outer sheet layer in the circumferential direction. In the portion where the intermediate sheet layer and the outer sheet layer are laminated and integrated in the thickness direction of the solar cell adhesive sheet, the total thickness of the outer sheet layer in the thickness direction of the solar cell adhesive sheet is the entire solar cell adhesive sheet. It adjusts so that it may become 30% or less of thickness, The manufacturing method of the adhesive sheet for solar cells of Claim 1 or Claim 2 characterized by the above-mentioned.

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