JP2012004487A - Solar cell back sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell back sheet whose reflection property is hardly deteriorated even under severe conditions.SOLUTION: The solar cell back sheet has a cured film, used as a reflection film, of a photosensitive resin composition comprising: an active energy ray curable resin (A) which has at least two ethylene unsaturated bonds in one molecule; a photopolymerization initiator (B); a diluent (C); titanium oxide (D); and an epoxy thermosetting compound (E). The photosensitive resin composition contains a bifunctional epoxy acrylate (A1) and/or a compound (C1) represented by the general formula (i).

Description

  The present invention relates to a solar battery back sheet having a cured film of a photosensitive resin composition.

Carbon dioxide increases and global warming due to the generated during fossil energy sources combustion, NO _X, measures for environmental destruction such as air pollution due to the release of SO _X has become an urgent task. Therefore, in recent years, solar cells that can directly obtain electricity from sunlight have attracted attention as a new energy source having no environmental load. A solar cell is a combination of a plurality of photovoltaic elements, and has a structure in which several to several tens of photovoltaic elements are wired in series and in parallel. Moreover, since a solar cell is installed in a natural environment for a long period of time, it is used as a solar cell module packaged with a cover material in order to protect the photovoltaic element.

  Specifically, the solar cell module is composed of an upper transparent material made of glass, transparent plastic, and the like, and a sealing layer made of a thermoplastic resin such as an ethylene vinyl acetate copolymer, in order from the side on which the sunlight hits. A plurality of photovoltaic cells in which photovoltaic elements are wired in series and in parallel, a sealing layer (a layer similar to the sealing layer), and a solar battery back sheet (reflection sheet) are laminated.

  The back sheet of the solar cell is installed as a protective member on the back surface side, and generally, a material excellent in impact resistance is used. In addition, the back sheet is required to have a white color tone having high reflectivity in order to effectively use the incident light to the solar cell module and increase the power conversion efficiency.

  On the other hand, since the solar cell module is installed outdoors for a long time, the solar cell backsheet is required to have good adhesion to the sealing layer and excellent properties such as weather resistance and moisture resistance. ing. Therefore, a solar battery backsheet provided with an adhesive coating layer made of a polyacrylic acid resin colored with a white pigment mainly composed of titanium oxide on the innermost surface bonded to the sealing layer constituting the solar battery module. Providing is proposed (Patent Document 1).

  Moreover, it is obtained from (A) alicyclic skeleton epoxy resin as a photosensitive resin composition for suppressing discoloration due to ultraviolet rays or heat and a decrease in reflectance, and has at least two ethylenically unsaturated bonds in one molecule. Photosensitivity containing active energy ray-curable resin, (B) thiol compound, (C) photopolymerization initiator, (D) diluent, (E) rutile titanium oxide, and (F) epoxy thermosetting compound Resin compositions are known (Patent Document 2).

JP 2010-109240 A JP 2008-211036 A

  As mentioned above, solar cells are installed outdoors and may be exposed to harsh conditions such as high temperature and humidity. Therefore, the solar cell back sheet has a reflective property (reflectance) even under harsh conditions. Is required to remain unchanged.

  Further, as in Patent Document 2, when a photosensitive resin composition is used as a white paint for a solar battery backsheet, even if the base film has good impact resistance, it depends on the photosensitive resin composition. If cracks are likely to occur in the cured film, the reflection characteristics of the solar cell backsheet may change.

  Thus, the problem to be solved by the present invention is a photosensitive resin that can form a cured film having excellent impact resistance without changing reflection characteristics (reflectance) even under severe conditions. It is an object of the present invention to provide a solar battery back sheet having a cured film of the composition.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive research. As a result, a photosensitive resin composition containing a bifunctional epoxy acrylate as an active energy ray-curable resin, or at least two ethylenic groups in one molecule. By using a photosensitive resin composition containing an active energy ray-curable resin having a saturated bond and a compound (diluent) having a specific structure, it is caused by changes in reflection characteristics even under high temperature and high humidity conditions, and generation of cracks due to impact. It was possible to form a cured film that hardly caused changes in reflection characteristics, and the cured product of these photosensitive resin compositions was found to be suitable as a reflective film for a solar battery back sheet, and the present invention was completed. . That is, the present invention relates to the following (1) to (9).

（式中、Ｒ^１〜Ｒ^３は、それぞれ独立してメチル基又は水素原子を表し、Ｒ^４〜Ｒ^６は、それぞれ独立して、炭素数２〜５のアルキレン基を表し、ｌ、ｍ及びｎは、ｌ＋ｍ＋ｎ≦１５を満たす自然数である。）で表される化合物を含有する感光性樹脂組成物の硬化膜を反射皮膜として有する、太陽電池バックシート。
（３）１分子中に少なくとも２個のエチレン性不飽和結合を有する活性エネルギー線硬化性樹脂（Ａ）と、光重合開始剤（Ｂ）と、希釈剤（Ｃ）と、酸化チタン（Ｄ）と、エポキシ系熱硬化性化合物（Ｅ）とを含有する感光性樹脂組成物であって、（Ａ）成分として、二官能のエポキシ（メタ）アクリレートを含有し、（Ｃ）成分として、下記一般式（ｉ）

（式中、Ｒ^１〜Ｒ^３は、それぞれ独立してメチル基又は水素原子を表し、Ｒ^４〜Ｒ^６は、それぞれ独立して、炭素数２〜５のアルキレン基を表し、ｌ、ｍ及びｎは、ｌ＋ｍ＋ｎ≦１５を満たす自然数である。）で表される化合物を含有する感光性樹脂組成物の硬化膜を反射皮膜として有する、太陽電池バックシート。
（４）前記感光性樹脂組成物が、前記エポキシ（メタ）アクリレート（Ａ１）を、（Ａ）成分全量に対して４〜３５質量％含有することを特徴とする、（１）又は（３）に記載の太陽電池バックシート。
（５）前記感光性樹脂組成物が、前記一般式（ｉ）で表される化合物を、（Ａ）成分１００質量部に対して、２〜１００質量部含有することを特徴とする、（２）又は（３）に記載の太陽電池バックシート。
（６）前記感光性樹脂組成物が、（Ａ）成分として、アクリル酸及び／又はメタクリル酸と、アクリル酸エステル及び／又はメタクリル酸エステルとの共重合樹脂のカルボキシル基に対して、エチレン性不飽和結合を有する脂環式エポキシを反応させて得られる活性エネルギー線硬化性樹脂（Ａ２）を含有することを特徴とする、（１）〜（５）何れかに記載の太陽電池バックシート。
（７）前記感光性樹脂組成物が、（Ａ）成分として、分子中にエポキシ基を２個以上有する脂環式エポキシのエポキシ基の全部又は一部に、ラジカル重合性不飽和モノカルボン酸を反応させて分子中に二個以上のエチレン性不飽和結合を導入し、さらに生成した水酸基に多塩基酸無水物を反応させることにより得られる活性エネルギー線硬化性樹脂（Ａ３）を含有することを特徴とする、（１）〜（６）何れかに記載の太陽電池バックシート。
（８）前記２官能のエポキシ（メタ）アクリレートが、ビスフェノール型エポキシ（メタ）アクリレート又は変性ビスフェノール型エポキシ（メタ）アクリレートである、（１）、（３）又は（４）に記載の太陽電池バックシート。
（９）（１）〜（８）いずれかに記載の太陽電池バックシートを備えた太陽電池モジュール。 (1) Active energy ray-curable resin (A) having at least two ethylenically unsaturated bonds in one molecule, photopolymerization initiator (B), diluent (C), and titanium oxide (D) And an epoxy-based thermosetting compound (E), wherein the photosensitive resin composition contains a bifunctional epoxy (meth) acrylate (A1) as a component (A). A solar battery back sheet having a cured film as a reflective film.
(2) Active energy ray-curable resin (A) having at least two ethylenically unsaturated bonds in one molecule, photopolymerization initiator (B), diluent (C), and titanium oxide (D) And an epoxy-based thermosetting compound (E), the component (C) having the following general formula (i)

(In the formula, R ^{1 to} R ³ each independently represent a methyl group or a hydrogen atom, R ^{4 to} R ⁶ each independently represents an alkylene group having 2 to 5 carbon atoms, l, m and n is a natural number satisfying l + m + n ≦ 15.) A solar battery backsheet having a cured film of a photosensitive resin composition containing a compound represented by:
(3) Active energy ray-curable resin (A) having at least two ethylenically unsaturated bonds in one molecule, photopolymerization initiator (B), diluent (C), and titanium oxide (D) And an epoxy-based thermosetting compound (E), which contains a bifunctional epoxy (meth) acrylate as the component (A) and the following general components as the component (C): Formula (i)

(In the formula, R ^{1 to} R ³ each independently represent a methyl group or a hydrogen atom, R ^{4 to} R ⁶ each independently represents an alkylene group having 2 to 5 carbon atoms, l, m and n is a natural number satisfying l + m + n ≦ 15.) A solar battery backsheet having a cured film of a photosensitive resin composition containing a compound represented by:
(4) The photosensitive resin composition contains 4 to 35% by mass of the epoxy (meth) acrylate (A1) with respect to the total amount of the component (A), (1) or (3) The solar cell back sheet as described in 2.
(5) The photosensitive resin composition contains 2 to 100 parts by mass of the compound represented by the general formula (i) with respect to 100 parts by mass of the component (A). ) Or the solar cell backsheet according to (3).
(6) The photosensitive resin composition has, as component (A), an ethylenic non-reactive compound with respect to the carboxyl group of a copolymer resin of acrylic acid and / or methacrylic acid and acrylic acid ester and / or methacrylic acid ester. The solar cell backsheet according to any one of (1) to (5), comprising an active energy ray-curable resin (A2) obtained by reacting an alicyclic epoxy having a saturated bond.
(7) The photosensitive resin composition has a radically polymerizable unsaturated monocarboxylic acid as a component (A) on all or part of the epoxy group of the alicyclic epoxy having two or more epoxy groups in the molecule. Containing an active energy ray-curable resin (A3) obtained by reacting, introducing two or more ethylenically unsaturated bonds into the molecule, and reacting a polybasic acid anhydride with the generated hydroxyl group; The solar cell backsheet according to any one of (1) to (6).
(8) The solar battery back according to (1), (3) or (4), wherein the bifunctional epoxy (meth) acrylate is bisphenol-type epoxy (meth) acrylate or modified bisphenol-type epoxy (meth) acrylate Sheet.
(9) A solar cell module comprising the solar cell back sheet according to any one of (1) to (8).

  According to the photosensitive resin composition according to the present invention, it is possible to form a reflective film of a solar battery back sheet capable of maintaining good reflectance characteristics even under severe conditions.

（式中、Ｒ^１〜Ｒ^３は、それぞれ独立してメチル基又は水素原子を表し、Ｒ^４〜Ｒ^６は、それぞれ独立して、炭素数２〜５のアルキレン基を表し、ｌ、ｍ及びｎは、ｌ＋ｍ＋ｎ≦１５を満たす自然数である。）で表される化合物（Ｃ１）を含有することを特徴とする。以下、これら成分毎に詳細に説明する。 Hereinafter, the present invention will be described in detail according to embodiments.
[Photosensitive resin composition for solar cell backsheet]
The photosensitive resin composition for solar cell backsheets according to the present invention comprises an active energy ray-curable resin (A) having at least two ethylenically unsaturated bonds in one molecule, a photopolymerization initiator (B), , A photosensitive resin composition containing a diluent (C), titanium oxide (D), and an epoxy thermosetting compound (E), wherein the bifunctional epoxy (meth) acrylate (A1) and / or Or the following general formula (i)

(In the formula, R ^{1 to} R ³ each independently represent a methyl group or a hydrogen atom, R ^{4 to} R ⁶ each independently represents an alkylene group having 2 to 5 carbon atoms, l, m and n is a natural number satisfying l + m + n ≦ 15)), and is characterized by containing the compound (C1). Hereinafter, each of these components will be described in detail.

(A) component
(A1)
A bifunctional epoxy (meth) acrylate is obtained by introducing two or more (meth) acryloyloxy groups into a compound having two or more epoxy groups in the molecule by utilizing a ring-opening reaction of the epoxy group. If it is a compound, there will be no restriction | limiting in particular, You may modify | denature with polyester, polyether, or amine. Examples of such compounds include bisphenol type epoxy (meth) acrylate (for example, bisphenol A type epoxy (meth) acrylate, bisphenol F type epoxy (meth) acrylate), amine-modified bisphenol type epoxy (meth) acrylate, and the like. It is done. By using a bifunctional epoxy (meth) acrylate, it becomes possible to prevent the occurrence of cracks during the production of the substrate.

  Among these bifunctional epoxy (meth) acrylates, as bisphenol A type epoxy acrylate, lipoxy SP-2600 (manufactured by Showa Polymer), NK oligo EA-1020, NK oligo EA-6340 (manufactured by Shin-Nakamura Chemical), Karayad R-280, Karayad R-190 (manufactured by Nippon Kayaku), Ebecryl 600, Ebecryl 3700 (Daicel Cytec), etc. are on the market. As for the modified bisphenol A type epoxy acrylate, KRM7856, Ebecryl 3604, Ebecryl 3702, Ebecryl 3703, Ebecryl 3708 (Daicel Cytec), LR9019 (BASF) and the like are marketed. These bifunctional epoxy (meth) acrylates may be used alone or in combination of two or more.

  The blending amount of the bifunctional epoxy (meth) acrylate is not particularly limited. However, in order to sufficiently exhibit the effect of preventing the occurrence of cracks, it is used in an amount of 4 to 35% by mass with respect to the entire component (A). Is preferred. Furthermore, in order to ensure favorable heat resistance, the range of 15-25 mass% is preferable.

(A2)
(A2) reacts an alicyclic epoxy having an ethylenically unsaturated bond with a carboxyl group of a copolymer resin of acrylic acid and / or methacrylic acid and acrylic acid ester and / or methacrylic acid ester. The resulting active energy ray-curable resin. Here, the alicyclic epoxy refers to a compound in which the carbon constituting the epoxy group simultaneously constitutes the alicyclic skeleton. Although there is no restriction | limiting in particular of an epoxy equivalent, Usually 1000 or less, Preferably the thing of 100-500 is used.

  Specific examples of (A2) include, for example, an alicyclic ring having an ethylenically unsaturated bond with respect to a carboxyl group of a copolymer resin of acrylic acid and / or methacrylic acid and acrylic ester and / or methacrylic ester. Examples of the formula epoxy include energy ray-curable resins obtained by reacting (3,4-epoxycyclohexyl) methyl acrylate and / or (3,4-epoxycyclohexenyl) methyl acrylate. These resins are commercially available from Daicel Chemical Industries, Ltd. as Cyclomer P series (such as Cyclomer P (ACA) Z-251, Cyclomer P (ACA) Z-250, Cyclomer P (ACA) Z300)). What has been used can be preferably used.

(A3)
(A3) is a reaction of a radically polymerizable unsaturated monocarboxylic acid with two or more of the epoxy groups of an alicyclic epoxy having two or more epoxy groups in the molecule, and a polybasic acid or its It is an active energy ray-curable resin obtained by reacting an anhydride. Examples of the alicyclic epoxy include 1,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, vinylcyclohexenediexoxide, 1,2-bis (hydroxymethyl) -1-butanol. Examples include 2-epoxy-4- (2-oxiranyl) cyclohexane adduct. Of these, 1,2-epoxy-4- (2-oxiranyl) cyclohexane adduct of 2,2-bis (hydroxymethyl) -1-butanol should be obtained as “EHPE-3150” manufactured by Daicel Chemical Industries. I can do it.

  The radically polymerizable unsaturated monocarboxylic acid to be used is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, crotonic acid, cinnamic acid and the like. At least one of acrylic acid and methacrylic acid is preferable, and acrylic acid is particularly preferable. Is preferred. There is no restriction | limiting in particular in the reaction method of an alicyclic epoxy resin and radically polymerizable unsaturated monocarboxylic acid, For example, it can react by heating an epoxy resin and acrylic acid in a suitable diluent.

  The polybasic acid or polybasic acid anhydride reacts with a hydroxyl group produced by the reaction between the alicyclic epoxy and the radically polymerizable unsaturated monocarboxylic acid to give a free carboxyl group. The polybasic acid to be used or its anhydride is not particularly limited, and either saturated or unsaturated can be used. Polybasic acids include, for example, succinic acid, maleic acid, adipic acid, citric acid, phthalic acid, tetrahydrophthalic acid, 3-methyltetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, 3-ethyltetrahydrophthalic acid, 4- Ethyltetrahydrophthalic acid, hexahydrophthalic acid, 3-methylhexahydrophthalic acid, 4-methylhexahydrophthalic acid, 3-ethylhexahydrophthalic acid, 4-ethylhexahydrophthalic acid, methyltetrahydrophthalic acid, methylhexahydro Examples include phthalic acid, endomethylenetetrahydrophthalic acid, methylendomethylenetetrahydrophthalic acid, trimellitic acid, pyromellitic acid, and diglycolic acid. Examples of polybasic acid anhydrides include these anhydrides. These compounds may be used alone or in combination of two or more.

(A4)
(A4) is an active energy ray obtained by reacting two or more epoxy groups of a bisphenol type epoxy resin with a radical polymerizable unsaturated monocarboxylic acid, and further reacting a polybasic acid anhydride with the generated hydroxyl group. It is a curable resin. Examples of the bisphenol type epoxy resin include bisphenol A type epoxy resin, bisphenol A novolak type epoxy resin, and bisphenol F type epoxy resin. As the radically polymerizable unsaturated monocarboxylic acid, polybasic acid and polybasic acid anhydride, the same ones as described in (A3) can be used.

The (B) component photopolymerization initiator is not particularly limited as long as it is generally used. For example, oxime initiators, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n- Butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2- Propyl) ketone Benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ethyl ester, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide And phosphine oxide initiators such as bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide. These can be used alone or in combination. When the amount of the photopolymerization initiator used is small, it requires an exposure time during the operation, and when it is large, the amount of volatile components during heat curing increases, which may contaminate the drying furnace. ) 5 to 20 parts by mass, more preferably 8 to 15 parts by mass with respect to 100 parts by mass of the component.

で表される化合物である。ここで、式（ｉ）において、Ｒ^１〜Ｒ^３は、それぞれ独立してメチル基又は水素原子を表し、Ｒ^４〜Ｒ^６は、それぞれ独立して、炭素数２〜５のアルキレン基を表し、ｌ、ｍ及びｎは、ｌ＋ｍ＋ｎ≦１５を満たす自然数である。炭素数２〜５のアルキレン基としては、エチレン基、プロピレン基が好ましい。なお、炭素数２〜５のアルキレン基は、分岐状又は直鎖状のいずれでも良い。 (C) component
(C1)
(C1) is represented by the following general formula (i)

It is a compound represented by these. Here, in formula (i), R ^{1 to} R ³ each independently represent a methyl group or a hydrogen atom, and R ^{4 to} R ⁶ each independently represents an alkylene group having 2 to 5 carbon atoms. , L, m, and n are natural numbers that satisfy l + m + n ≦ 15. The alkylene group having 2 to 5 carbon atoms is preferably an ethylene group or a propylene group. Note that the alkylene group having 2 to 5 carbon atoms may be branched or linear.

  Specifically, as (C1), ethoxylated (3) trimethylolpropane triacrylate such as SR454 manufactured by Sartomer, ethoxylated (6) trimethylolpropane triacrylate such as SR499 manufactured by the same company, CD501 manufactured by the same company, etc. Propoxylated (6) trimethylol propane triacrylate and ethoxylated (15) trimethylol propane triacrylate such as SR9035 manufactured by the same company (the numbers in parentheses are 1 in the above general formula (i), meaning the total number of m and n).

  As a blending amount of (C1), in order to obtain a sufficient crack prevention effect, a range of 2 to 100 parts by mass, and further 20 to 40 parts by mass with respect to 100 parts by mass of component (A) is preferable.

  As the component (C) other than the above (C1), generally known diluents can be used. A typical diluent is a photopolymerizable monomer. The photopolymerizable monomer is also referred to as a reactive diluent, which further enhances the photocuring of the photosensitive resin as the component (A) to obtain a coating film having acid resistance, heat resistance, alkali resistance, and the like. It is intended for use. As the reactive diluent, a compound having at least two double bonds in one molecule is preferably used.

  Typical examples of the photopolymerizable monomer (reactive diluent) include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and neopentyl glycol di (meth). ) Acrylate, polyethylene glycol di (meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone-modified dicyclopentenyl di ( (Meth) acrylate, ethylene oxide modified phosphoric acid di (meth) acrylate, allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipenta Lithritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, alkylene oxide modified trimethylolpropane tri (meth) acrylate, bisphenol A type ethylene oxide modified di (meth) Acrylate, bisphenol A type propylene oxide modified di (meth) acrylate caprolactone modified dipentaerythritol hexaacrylate, ethylene oxide modified dipentaerythritol hexaacrylate, tris (acryloxyethyl) isocyanurate, propionic acid modified dipentaerythritol penta (meth) acrylate , Dipentaerythritol hexa (meth) acrylate, caprolactone modified dipentaery Ritoruhekisa (meth) reactive diluents such as acrylate. Examples of the oxyalkylene group in the alkylene oxide-modified trimethylolpropane tri (meth) acrylate include oxyalkylene groups having 2 to 10 carbon atoms (preferably 2 to 4 carbon atoms). Examples of such include ethylene oxide-modified trimethylol prepane tri (meth) acrylate and propylene oxide-modified trimethylolpropane tri (meth) acrylate.

  Moreover, it is also possible to use the compound represented by the following general formula (ii) as a reactive diluent.

In the formula (ii), R ⁷ and R ⁸ each independently represent a hydrogen atom or a methyl group, and p and q represent natural numbers of p + q ≦ 10 or less.

  The content of the component (C) other than the above (C1) is not particularly limited. However, when the amount is small, the effect of shortening the photocuring time cannot be achieved. Since there exists a possibility that crack prevention property may not be obtained, 2-200 mass parts with respect to 100 mass parts of (A) component, Furthermore, 10-50 mass parts is preferable.

(D) As a component titanium oxide, the titanium oxide which has a rutile crystal structure can be used conveniently. A coating film can be whitened by mix | blending a titanium oxide. The average particle diameter of titanium oxide is not particularly limited, but is preferably in the range of 0.01 to 1 μm. Titanium oxide may be either untreated or surface-treated. As a compounding quantity of a titanium oxide, the range of 10-100 mass parts with respect to 100 mass parts of (A) component, Furthermore, the range of 50-100 mass parts is preferable. When the blending amount of titanium oxide is less than 10 parts by mass, the whiteness is not sufficient, and when it exceeds 100 parts by mass, the strength may be adversely affected.

(E) Component epoxy-based thermal effect compound is a sufficiently tough coating film (coating hardness, heat resistance, durability, chemical resistance, post-cure after exposing the coating film of the photosensitive resin composition, Environment resistance, etc.).

  As a typical epoxy thermosetting compound, an epoxy resin (including an epoxy oligomer) having at least one epoxy group, preferably two or more epoxy groups in one molecule is preferable, but not limited thereto. Absent. For example, a bisphenol A type epoxy resin obtained by reacting bisphenol A and epichlorohydrin in the presence of an alkali, an epoxidized product of a resin obtained by condensation reaction of bisphenol A and formalin, Instead, those using brominated bisphenol A, novolak type epoxy resins obtained by reacting novolak resin with epichlorohydrin to glycidyl ether (phenol novolak type epoxy resin, o-cresol novolak type epoxy resin, p-tert-butylphenol novolak type, etc. ), Bisphenol F-type and bisphenol S-type epoxy resins obtained by reacting bisphenol F and bisphenol S with epichlorohydrin, cyclohexene oxide groups, tricyclode Such as cycloaliphatic epoxy resins having thiol oxide groups, cyclopentene oxide groups, diglycidyl phthalate, diglycidyl tetrahydrophthalate, diglycidyl hexahydrophthalate, diglycidyl-p-hydroxybenzoic acid, glycidyl dimer, etc. Glycidyl ester resins, tetraglycidyl diaminodiphenylmethane, glycidylamine resins such as triglycidyl-p-aminophenol, (propylene, polypropylene) glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane poly Glycidyl ether, resorcin diglycidyl ether, 1,6 hexanediol diglycidyl ether, , Propylene) glycol diglycidyl ether, sorbitol polyglycidyl ether, sorbitan polyglycidyl ether, glycidyl ether resins such as pentaerythritol polyglycidyl ether, tris (2,3-epoxypropyl) isocyanurate, triglycidyl tris (2-hydroxyethyl) ) Triglycidyl isocyanurate having a triazine ring such as isocyanurate, dicyclopentadiene type epoxy resin and the like. These epoxy thermosetting resin compounds may be used alone or in combination. As a compounding quantity of these epoxy-type thermosetting resin compounds, it is 2-20 mass parts with respect to 100 mass parts of (A) component from a viewpoint of obtaining sufficient coating film hardness after hardening, Furthermore, 5-15 mass parts The range of is preferable.

  In addition to the above components, the photosensitive resin composition according to the exemplary embodiment of the present invention contains various additive components, for example, an antifoaming agent, various additives, extender pigments, a solvent, and the like as necessary. be able to.

  A well-known thing can be used for an antifoamer, for example, a silicone type, a hydrocarbon type, an acrylic type etc. can be mentioned.

  Examples of additives include dispersants such as coupling agents such as silane, titanate, and alumina, boron trifluoride-amine complex, dicyandiamide (DICY) and its derivatives, organic acid hydrazide, and diaminomaleonitrile (DAMN). And its derivatives, melamine and its derivatives, guanamine and its derivatives, amine imide (AI) and latent curing agents such as polyamine, metal salts of acetylacetone such as acetylacetonate Zn and acetylacetonate Cr, enamine, tin octylate, Examples include quaternary sulfonium salts, triphenylphosphine, imidazole, imidazolium salts, and thermosetting accelerators such as triethanolamine borate.

  The extender is for increasing the physical strength of the coated film, and examples thereof include silica, barium sulfate, alumina, aluminum hydroxide, talc, and mica.

  As the solvent, an organic solvent is suitable, for example, ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, alcohols such as methanol, isopropanol and cyclohexanol, cyclohexane, methylcyclohexane and the like. Aliphatic hydrocarbons, petroleum solvents such as petroleum ether and petroleum naphtha, cellosolves such as cellosolve and butylcellosolve, carbitols such as carbitol and butylcarbitol, ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate And acetate esters such as carbitol acetate and butyl carbitol acetate. When using an organic solvent, the amount of use is preferably 10 to 500 parts by mass, more preferably 10 to 40 parts by mass with respect to 100 parts by mass of (A) the photosensitive resin.

The method for producing the photosensitive resin composition according to the above-described embodiment of the present invention is not limited to a specific method. For example, after blending each of the above components at a predetermined ratio, the mixture is dispersed by a three roll at room temperature. Can be manufactured.
The cured product of the photosensitive resin composition of the present invention produced in this way has good reflectance and impact resistance (crack resistance). The reflectance is 85% or more, preferably 90% or more, at the stage immediately after the formation of the coating film, and is maintained under this high reflectance when exposed to high temperature and high humidity.

In the photosensitive resin composition according to the present invention, as described above, in order to improve the reflectance under high temperature and high humidity and the impact resistance of the cured coating film, the above (A1) and / or (C1) It is characterized by using. In the present invention, particularly preferred photosensitive resin compositions are as follows.
-By using together (A1) and (A2) and / or (A3) the photosensitive resin composition which (A) component consists of (A1) and (A2) and / or (A3): In addition to good reflectivity and cracking prevention effect, sufficient coating film hardness can be obtained. At this time, from the viewpoint of the effect of preventing cracking, discoloration resistance and reflectance, the component (A1) is 4 to 35% by mass with respect to the total component (A), and the balance is (A2) and / or (A3) is preferable.
Photosensitive resin composition comprising (A) component (A2) and (C) component (C1): good coating film hardness, balanced discoloration resistance, reflectance and crack resistance Good and excellent. In this case, (C1) is preferably blended in an amount of 20 to 40 parts by mass with respect to 100 parts by mass of (A1).
A photosensitive resin composition comprising (A) component (A1) and (A2) and / or (A3), and (C) component (C1): coating film hardness, discoloration resistance, reflection The ratio and heat resistance are excellent in balance, and the crack resistance is most excellent. Under the present circumstances, from a viewpoint of the crack generation prevention effect, discoloration resistance, and the balance of a reflectance, (A1) component shall be 4-35 mass% with respect to the whole (A) component, and (C1) is (A1) 100 mass parts. It is preferable to mix | blend 20-40 mass parts with respect to.

[Solar cell back sheet]
Next, an example of a method for producing the solar battery back sheet of the present invention by coating the above-described photosensitive resin composition on the surface of the sheet-like base film will be described. After the surface of the sheet-like base film is treated with, for example, an acid and washed, the photosensitive resin composition obtained as described above is applied to the washed surface with a predetermined thickness (for example, 5 to 100 μm). , Preferably 10 to 30 μm), for example, using a screen printing method. After coating, preliminary drying is performed by heating at a temperature of about 60 to 80 ° C. for about 15 to 60 minutes. Thereafter, the applied composition is irradiated with ultraviolet rays. The ultraviolet irradiation conditions, for example, the ultraviolet rays having a wavelength of ^{300~450nm, 200mJ / cm 2 ~600mJ /} cm 2, preferably at 300~500mJ / cm ^2, it is preferable to irradiate 30-50 seconds.
In the case of forming a pattern on the base film, for example, by attaching a negative film of the pattern and irradiating it with ultraviolet rays, the non-exposed area corresponding to this soldering land is removed with a dilute alkaline aqueous solution. A patterned coating film can be obtained. This removal may be any of dissolution, swelling, peeling, etc. of the unexposed part. The dilute alkaline aqueous solution used at this time is generally 0.5 to 5% sodium carbonate aqueous solution, but other alkalis can also be used.
Subsequently, the post-cure (post-heat treatment in a hot air drying furnace) is performed at a temperature of 130 to 170 ° C., preferably 140 to 160 ° C. for 10 to 80 minutes, and for 50 to 70 minutes. A white solar battery back sheet can be produced by forming a white cured coating film. The cured coating film formed in this manner usually has a thickness of 5 to 100 μm, preferably 10 to 50 μm.

  The material of the sheet-like base film is not particularly limited. For example, polyimide, polyethylene terephthalate (PET), polyvinyl fluoride (PVF), fluorinated ethylene / propylene copolymer (FEP), and polytetrafluoroethylene (PTFE). , Aramid, polyamide-imide, epoxy, polyetherimide, polysulfone, polyethylene naphthalate (PEN), liquid crystal polymer (LCP), and the like.

[Solar cell module]
The solar battery backsheet of this invention comprises a solar cell module combining with a photovoltaic cell. Usually, a surface sheet, a sealing layer in which solar cells are sealed with resin, and a back sheet are sequentially laminated to form a solar cell module. Furthermore, an adhesive layer may be provided when the adhesion is insufficient in the lamination.
As the top sheet, a glass substrate is usually used, but a flexible material such as a resin sheet may be used for the top sheet. The back sheet of the present invention can be suitably used for flexible solar cells because it has a thin film thickness and can be reduced in weight.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not restrict | limited by these Examples. In the following examples and comparative examples, the composition is expressed by weight ratio.
(1) Evaluation sample preparation method Each photosensitive compound was mixed and dispersed in the atmosphere and at room temperature using three rolls (manufactured by Inoue Seisakusho, S16) at the composition ratio shown in Table 1. A sex composition was prepared. Subsequently, the evaluation board | substrate test piece was produced on condition of the following using each photosensitive composition.

<Test substrate test piece preparation method>
The surface of a 40 μm thick polyethylene terephthalate film (“Lumirror” manufactured by Toray) was treated with 3% sulfuric acid and washed. Next, the photosensitive resin composition prepared as described above was applied to the film surface by a screen printing method so that the DRY film thickness was 20 to 23 μm. Then, the coating film was dried at 70 ° C. for 20 minutes (inside the furnace: 25 minutes) using a hot air circulating drying furnace (manufactured by Tabai Espec, (model number) PHH201) to form a dried coating film having a film thickness of 20 to 23 μm. . Next, using an ultraviolet exposure device (Oak Seisakusho, model HMW-680GW, using a metal halide lamp 7 kW), ultraviolet rays (300 to 450 nm) were irradiated onto the coating film at 400 mJ / cm ² (about 40 seconds), Thereafter, heat curing was performed at 150 ° C. for 60 minutes (inside the furnace: 70 minutes) using a hot-air circulating drying furnace to prepare a test substrate. As for the reflectivity after heating and humidification, a cured coating film is applied to a glass plate (1.2 mm thick) by the same method in order to eliminate the influence of deterioration of polyethylene terephthalate itself due to the environmental standing as an accelerated test. Formed and evaluated.

(2) Evaluation method (2-1) Discoloration evaluation (discoloration resistance)
After each test substrate was heated at 260 ° C. for 5 minutes, the discoloration was visually observed and evaluated according to the following criteria.
○: No discoloration, △: Some discoloration is observed, ×: Yellow discoloration

(2-2) Reflectance Measurement (2-2-1) Initial Using a spectrophotometer U3410 (manufactured by Hitachi, Ltd., φ60 mm integrating sphere), the reflectance at 450 nm of the cured coating film immediately after each test piece was prepared. Measured.

(2-2-1) After UV irradiation With respect to the cured coating film of each test piece, UV irradiation (300 to 450 nm) was applied to 50 J / cm ² (about approx. 2 minutes), and the reflectance at 450 nm after irradiation was measured in the same manner as in (2-3-1).

(2-2-2) After heating Each test piece was heated at 170 ° C. for 100 hours, and then the reflectance at 450 nm of the cured coating film was measured in the same manner as in (2-3-1).

(2-2-3) After heating and humidification, each test piece was allowed to stand at 85 ° C. and 85% RH for 1000 hours, and then with a spectrophotometer U-3410 (manufactured by Hitachi, Ltd .: φ60 mm integrating sphere) The reflectance of the cured coating film at 500 nm was measured.

(2-3) Cupping resistance The surface of a bonded steel plate (10 × 10 cm, thickness 0.8 mm) was washed with xylene to completely remove the oil, and a coating film was formed in the test piece preparation step. A film formed in the same manner as in the method was used as an evaluation substrate, and a cupping test was performed in accordance with JIS K-5600-5-2. That is, when a steel ball was extruded from the back surface of each test piece to deform the test piece, the extrusion distance (mm) until the coating film was cracked and peeled was measured.

(2-4) Coating film hardness A pencil of B to 9H, which has been sharpened so that the tip of the core becomes flat, is pressed against the cured coating film of each test piece at an angle of about 45 °, and the coating film peels off. The pencil hardness that did not occur was recorded.

(3) Evaluation results The evaluation results are shown in Table 1 below.
Table 1 shows that the cured coating film by the photosensitive resin composition of this invention has a favorable reflectance (90% or more) even after heating humidification (acceleration conditions). Further, the cupping resistance is a good value of 1.5 mm or more.

(Remarks)
Component (A) A1-1: Amine-modified bisphenol A type epoxy acrylate (Daicel Chemical Industries, EBECRYL3703)
A1-2: Modified epoxy acrylate (Daicel Chemical Industries, EBECRYL3708)
A2: Cyclomer P series (Cyclomer P (ACA) Z-251)
A3: 110 parts by mass of acrylic acid (unsaturated group-containing monocarboxylic acid) was added to 80 parts by dissolving 270 parts by mass of epoxy resin (manufactured by Daicel Chemical Industries, Ltd., EHPE-3150) in 400 parts by mass of cellosolve acetate. The reaction product was reacted under heating under reflux conditions for 8 hours, and 160 parts by mass of tetrahydrophthalic anhydride (polybasic acid anhydride) was reacted with this reaction product at 70 ° C. for 4 hours. At least two ethylenes in one molecule were obtained. Active energy ray-curable resin having a polymerizable unsaturated bond.
A4: As an epoxy resin, bisphenol A novolak type epoxy resin (Japan Epoxy Resin Co., Ltd. JER157S70) 220 parts by mass was dissolved in 120 parts by mass of diethylene glycol monoethyl ether acetate. An active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule obtained by reacting for 8 hours and then reacting 83 parts by mass of tetrahydrophthalic anhydride at 70 ° C. for 4 hours.

Component (B) B1: Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, manufactured by Ciba Specialty Chemicals, Irgacure 819
B2: 2.4.6-trimethylbenzoyldiphenylphosphine oxide, manufactured by Ciba Specialty Chemicals, DAROCURE TPO

・希釈剤２：下記式（ｉｖ）で表される反応性希釈剤（日本化薬社製、ＫＡＹＡＲＡＤ ＨＸ−６２０、ｐ＋ｑ＝６）

・希釈剤３（Ｃ１）：エトキシ化（３）トリメチロールプロパントリアクリレート、サートマー社製、ＳＲ４５４
・希釈剤４（Ｃ１）：エトキシ化（６）トリメチロールプロパントリアクリレート、サートマー社製、ＳＲ４９９
・希釈剤５（Ｃ１）：プロポキシ化（６）トリメチロールプロパントリアクリレート、サートマー社製、ＣＤ５０１
・希釈剤６（Ｃ１）：エトキシ化（１５）トリメチロールプロパントリアクリレート、サートマー社製、ＳＲ９０３５ (C) Component / Diluent 1: Caprolactone-modified dipentaerythritol hexaacrylate represented by the following formula (iii) (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPCA-60)

Diluent 2: Reactive diluent represented by the following formula (iv) (manufactured by Nippon Kayaku Co., Ltd., KAYARAD HX-620, p + q = 6)

Diluent 3 (C1): ethoxylated (3) trimethylolpropane triacrylate, manufactured by Sartomer, SR454
Diluent 4 (C1): ethoxylated (6) trimethylolpropane triacrylate, manufactured by Sartomer, SR499
Diluent 5 (C1): propoxylation (6) trimethylolpropane triacrylate, manufactured by Sartomer, CD501
Diluent 6 (C1): ethoxylated (15) trimethylolpropane triacrylate, manufactured by Sartomer, SR9035

(D) component: Titanium oxide, Ishihara Sangyo Co., Ltd., R-680
(E) component: Bisphenol A type epoxy resin, manufactured by Dainippon Ink and Chemicals, EPICLON860
Antifoaming agent: KS-66, manufactured by Shin-Etsu Chemical Co., Ltd.
Talc: Fuji Talc Industrial Co., Ltd., LMS
Additive 1: Silica, manufactured by Nippon Aerosil Co., Ltd., R-974
Additive 2: Dicyandiamide, manufactured by Japan Epoxy Resin, DICY-7
Additive 3: Pentaerythrityl-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenol) propionate), Ciba Specialty Chemicals, Irganox 1010
Additive 4: Melamine Solvent: Diethylene glycol monoethyl ether acetate, Sanyo Chemical Industries, EDGAC

Claims (9)

Active energy ray-curable resin (A) having at least two ethylenically unsaturated bonds in one molecule, photopolymerization initiator (B), diluent (C), titanium oxide (D), and epoxy A photosensitive resin composition containing a thermosetting compound (E),
(A) The solar cell backsheet which has a cured film of the photosensitive resin composition containing bifunctional epoxy (meth) acrylate (A1) as a component as a reflecting film. Active energy ray-curable resin (A) having at least two ethylenically unsaturated bonds in one molecule, photopolymerization initiator (B), diluent (C), titanium oxide (D), and epoxy A photosensitive resin composition containing a thermosetting compound (E),
As component (C), the following general formula (i)

(In the formula, R ^{1 to} R ³ each independently represent a methyl group or a hydrogen atom, R ^{4 to} R ⁶ each independently represents an alkylene group having 2 to 5 carbon atoms, l, m and n is a natural number satisfying l + m + n ≦ 15.) A solar battery backsheet having a cured film of a photosensitive resin composition containing a compound represented by: Active energy ray-curable resin (A) having at least two ethylenically unsaturated bonds in one molecule, photopolymerization initiator (B), diluent (C), titanium oxide (D), and epoxy A photosensitive resin composition containing a thermosetting compound (E),
As a component (A), a bifunctional epoxy (meth) acrylate is contained,
As component (C), the following general formula (i)

(In the formula, R ^{1 to} R ³ each independently represent a methyl group or a hydrogen atom, R ^{4 to} R ⁶ each independently represents an alkylene group having 2 to 5 carbon atoms, l, m and n is a natural number satisfying l + m + n ≦ 15.) A solar battery backsheet having a cured film of a photosensitive resin composition containing a compound represented by:   The said photosensitive resin composition contains 4-35 mass% of said epoxy (meth) acrylate (A1) with respect to (A) component whole quantity, The Claim 1 or Claim 3 characterized by the above-mentioned. Solar cell backsheet.   The photosensitive resin composition contains 2 to 100 parts by mass of the compound represented by the general formula (i) with respect to 100 parts by mass of the component (A). Item 4. The solar cell backsheet according to Item 3.   The photosensitive resin composition has an ethylenically unsaturated bond as a component (A) with respect to the carboxyl group of a copolymer resin of acrylic acid and / or methacrylic acid and acrylic acid ester and / or methacrylic acid ester. The solar cell backsheet according to any one of claims 1 to 5, further comprising an active energy ray-curable resin (A2) obtained by reacting an alicyclic epoxy resin.   The photosensitive resin composition reacts with all or part of the epoxy groups of the alicyclic epoxy having two or more epoxy groups in the molecule as the component (A), and a radical polymerizable unsaturated monocarboxylic acid. It contains an active energy ray-curable resin (A3) obtained by introducing two or more ethylenically unsaturated bonds into a molecule and reacting a polybasic acid anhydride with the generated hydroxyl group. The solar cell backsheet according to any one of claims 1 to 6.   The solar cell backsheet according to claim 1, 3 or 4, wherein the bifunctional epoxy (meth) acrylate is bisphenol-type epoxy (meth) acrylate or modified bisphenol-type epoxy (meth) acrylate.   The solar cell module provided with the solar cell backsheet in any one of Claims 1-8.