JP5776541B2 - Protective sheet for solar cell and solar cell module - Google Patents

Description

  The present invention relates to a solar cell protective sheet excellent in durability, adhesion to a sealing material and adhesion durability, and further to a solar cell module using the sheet.

In recent years, solar cells have been attracting attention as a clean energy source free from environmental pollution due to an increase in awareness of environmental problems, and earnestly researched and put into practical use from the viewpoint of using solar energy as a useful energy resource.
There are various types of solar cell elements, and typical examples thereof include a crystalline silicon solar cell element, a polycrystalline silicon solar cell element, an amorphous silicon solar cell element, a copper indium selenide solar cell element, and a compound semiconductor solar. Battery elements and the like are known. Among these, polycrystalline silicon solar cell elements, amorphous silicon solar cell elements, and compound semiconductor solar cell elements are relatively low cost and can be increased in area. It has been broken. Among these solar cell elements, a thin film solar cell element represented by an amorphous silicon solar cell element in which silicon is laminated on a conductive metal substrate and a transparent conductive layer is further formed thereon is lightweight, Moreover, since it is rich in impact resistance and flexibility, it is considered promising as a future form in solar cells.

Of the solar cell modules, a simple one has a configuration in which a sealing material and a glass plate are sequentially laminated on both sides of the solar cell. A glass plate is still generally used as a protective material on the light receiving surface side of the sun because it is excellent in transparency, weather resistance, and scratch resistance. However, on the non-light-receiving surface side that does not require transparency, various protective sheets for solar cells other than the glass plate have been proposed in view of cost, safety, and workability (for example, Patent Document 1). Are being replaced by solar cell protection sheets. Furthermore, in order to further reduce the weight of the solar cell module, a solar cell protective sheet is being used as a light-receiving surface side protective member.
As the sealing material, an ethylene-vinyl acetate copolymer (hereinafter referred to as “EVA”) that is highly transparent and excellent in moisture resistance is usually used.

As a protective sheet for solar cells, (i) a single layer film such as a polyester film, (ii) a polyester film or the like provided with a vapor deposition layer of a metal oxide or a non-metal oxide, (iii) a polyester film, Examples include a multilayer film in which films such as a fluorine-based film, an olefin film, and an aluminum foil are laminated.
Since the protective sheet for solar cells maintains insulation, a thick film is required, and a polyester film is mainly used as a base material due to cost requirements. However, the polyester film is remarkably bad with respect to heat and moisture resistance. (Patent Documents 2-4)

  Then, in order to improve the durability of the polyester film, it is known to use a polyester film that suppresses hydrolysis under high temperature and high humidity by reducing the cyclic trimer content (Patent Document 5- 6). However, this polyester film with high heat and moisture resistance has a drawback that the adhesion to the sealing material and the adhesion durability are extremely poor.

  Among various performances required for a protective sheet for a solar cell, adhesion to a sealing material and adhesion durability are basic and important performance requirements. If the adhesiveness to the sealing material is insufficient, the solar cell protective sheet is peeled off, and the solar cell cannot be protected from moisture or external factors, leading to deterioration of the output of the solar cell.

  As a method of ensuring the adhesiveness with the sealing material, (1) a method of subjecting the surface of the solar cell protective sheet to contact with the sealing material, and (2) a solar cell protective sheet sealing material A method of using a film having high adhesiveness to the sealing material on the surface to be in contact with can be mentioned.

Examples of the method (1) include surface treatment such as corona treatment, and easy adhesion coating treatment in which an easy adhesive is applied.
However, the former surface treatment such as corona treatment ensures initial adhesion, but has a problem of poor adhesion durability.
Patent Documents 1, 7, and 8 disclose easy adhesives used in the latter case of easy adhesive coating.

  Patent Document 7 discloses a crosslinking agent selected from the group consisting of an oxazoline group-containing polymer, a urea resin, a melamine resin, and an epoxy resin, and a crosslinking agent selected from a polyester resin or an acrylic resin having a glass transition point of 20 to 100 ° C. A coating liquid containing a resin component is disclosed (see claims 2 and 3 of the same document). More specifically, an example using a coating liquid containing an epoxy resin and an acrylic resin is described (see Example 5 of the same document). However, the adhesive strength with the EVA sheet in this example is about 10 to 20 N with a width of 20 mm (that is, 7.5 to 15 N with a width of 15 mm) (see Table 2 of the same document). Since the adhesiveness between the sealing material and the protective sheet for solar cells greatly affects the output degradation of the solar cells, higher adhesiveness is required in the market, and reliability of adhesive performance under more severe conditions is required. It has become to. However, an adhesive strength of about 20 N with a width of 20 mm cannot meet such market demands.

  Patent Document 8 discloses an adhesion improvement layer in which at least one resin selected from the group consisting of polyester resins and polyester polyurethane resins is crosslinked with an alkylated melamine or polyisocyanate crosslinking agent on a polyester film. The structure provided in the surface which contact | connects the sealing material of the protection sheet for batteries is disclosed.

As a method of the above (2) (a method of using a film having high adhesiveness to the sealing material on the surface in contact with the sealing material of the solar cell protective sheet), for example, Patent Document 9 discloses polybutylene terephthalate ( A method of using (PBT) is described.
However, since such a film generally has a thickness of several tens of μm, the cost becomes higher than the above easy adhesion treatment.

Patent Document 10 discloses an acrylic polymer obtained by polymerizing a monomer component containing a monomer represented by the following general formula (I) on a surface bonded to a filler (encapsulant) layer constituting a solar cell module. A back sheet for a solar cell module is disclosed, in which an adhesive layer made of an acrylic adhesive containing s is formed.
<Chemical Formula 1> CH ₂ = C (R ¹ ) —CO—OZ Formula (1)
In formula (1), R ¹ represents a hydrogen atom or a methyl group, and Z represents a hydrocarbon group having 4 to 25 carbon atoms.
Patent Document 11 discloses a polymer having a fluorine copolymer, an acrylic copolymer, or a polyurethane copolymer (polymer a) and one or more ethylenically unsaturated groups for photocuring. Solar cell having a primer layer comprising a monomer and / or oligomer (monomer b) and / or a compound (polyisocyanate c) containing one or more ethylenically unsaturated groups and two or more isocyanate groups in the molecule A protective sheet for a solar cell of an element is disclosed.

JP 2009-246360 A Japanese Patent Laid-Open No. 2004-200322 JP 2004-223925 A JP 2001-119051 A JP 2002-134770 A JP 2002-134771 A JP 2006-152013 A JP 2007-136911 A JP 2010-114154 A JP 2010-263193 A JP 2011-18872 A

  An object of the present invention is to provide a solar cell protective sheet excellent in durability, adhesion to a sealing material and adhesion durability, and further a solar cell module using the sheet.

The present invention is a protective sheet for a solar cell comprising an easy-adhesive layer (1 ′) as the outermost surface and a plastic film (2) having one main surface supporting the easy-adhesive layer (1 ′). There,
The easy-adhesive layer (1 ′) has a glass transition temperature of 10 to 100 ° C., a number average molecular weight of 15,000 to 250,000, and a hydroxyl value of 2 to 100 (mgKOH / g). The polyisocyanate compound (B) is contained in the range of 0.1 to 5 isocyanate groups with respect to one hydroxyl group in the copolymer (A) and the (meth) acrylic copolymer (A). , An easy-adhesive layer (1 ′) containing a carbon-carbon double bond derived from a (meth) acryloyl group in an amount defined by an iodine value of 0.01 to 50 (g / 100 g),
The plastic film (2) is a polyester film made of a polyester resin having an intrinsic viscosity of 0.6 (dl / g) or more and a cyclic trimer content of 1% by weight or less. The present invention relates to a solar cell protective sheet (Z ′).

The easy-adhesive layer (1 ′) as the outermost surface,
Contains an acrylic copolymer (A1) having a carbon-carbon double bond derived from a (meth) acryloyl group, or
It is related with the protective sheet (Z ') for solar cells characterized by containing the acrylic copolymer (A2) which does not have a (meth) acryloyl group, and the compound (C) which has a (meth) acryloyl group.

The (meth) acrylic copolymer (A1) is preferably a copolymer selected from the group consisting of the following (meth) acrylic copolymers (A1-1) to (A1-4).
(Meth) acrylic copolymer (A1-1): (meth) acrylic monomer (a1) having a glycidyl group, (meth) acrylic monomer (a2) having a hydroxyl group, glycidyl group, hydroxyl group and carboxyl group The (meth) acrylic monomer (a3) having a carboxyl group is reacted with the glycidyl group in the side chain in the copolymer having the (meth) acrylic monomer (a4) having no structural unit ( (Meth) acrylic copolymers,
(Meth) acrylic copolymer (A1-2): (meth) acrylic monomer (a3) having a carboxyl group, (meth) acrylic monomer (a2) having a hydroxyl group, glycidyl group and hydroxyl group are both carboxyl groups (Meth) acrylic monomer obtained by reacting a (meth) acrylic monomer (a1) having a glycidyl group with a carboxyl group in a copolymer having a (meth) acrylic monomer (a4) having no structural unit. Copolymer,
(Meth) acrylic copolymer (A1-3): Copolymer having a (meth) acrylic monomer (a2) having a hydroxyl group and a (meth) acrylic monomer (a6) having no hydroxyl group as structural units A (meth) acrylic copolymer obtained by reacting an isocyanate group-containing (meth) acrylic monomer (a5) with a part of the hydroxyl groups in the coalescence;
(Meth) acrylic copolymer (A1-4): a copolymer comprising maleic anhydride, an acrylic monomer (a2) having a hydroxyl group, and an acrylic monomer (a6) having no hydroxyl group as constituent units. A (meth) acrylic copolymer obtained by reacting an acid anhydride group therein with an acrylic monomer (a2) having a hydroxyl group.

  It is preferable to contain 0.1-20 weight part of compounds (C) which have a (meth) acryloyl group with respect to 100 weight part of the (meth) acrylic copolymer (A2). Moreover, it is preferable that the compound (C) which has a (meth) acryloyl group has 2 or more (meth) acryloyl groups in a molecule | numerator.

  The polyisocyanate compound (B) is preferably a blocked polyisocyanate (B1).

Furthermore, the present invention provides a solar cell surface protective material (I) positioned on the light receiving surface side of the solar cell, a sealing material (II) positioned on the light receiving surface side of the solar cell, a solar cell (III), and a solar cell. A solar cell module comprising a sealing material (IV) located on the non-light-receiving surface side, and a solar cell back surface protective material (V) located on the non-light-receiving surface side of the solar cell,
At least one of the solar cell surface protective material (I) and the solar cell surface protective material (V) is the solar cell protective sheet (Z ′), and the easy-adhesive layer (1 ′) is the It is arrange | positioned so that the sealing material of the light-receiving surface side or the sealing material of the said non-light-receiving surface side may be arrange | positioned, and it is related with the solar cell module obtained by hardening | curing the said easily adhesive layer for solar cell protective sheets. .

 The sealing material on the light receiving surface side or the sealing material on the non-light receiving surface side preferably contains an organic peroxide. Furthermore, the sealing material on the light receiving surface side or the sealing material on the non-light receiving surface side is preferably an ethylene-vinyl acetate copolymer (EVA).

  By using the solar cell protective sheet of the present invention, a solar cell protective sheet excellent in durability, adhesion to a sealing material and adhesion durability, and a solar cell module using the solar cell protective sheet are provided. It has an excellent effect of being able to. By using the solar cell protective sheet of the present invention, it is possible to provide a solar cell module with a small output drop even when exposed to a high temperature and high humidity environment for a long time.

It is a figure which shows typically the cross section of the module for solar cells of this invention.

Hereinafter, the present invention will be described in detail. Needless to say, other embodiments are also included in the scope of the present invention as long as they meet the spirit of the present invention. In addition, the numerical value range specified by using “to” in this specification includes numerical values described before and after “to” as ranges of the lower limit value and the upper limit value. In this specification, “film” and “sheet” are not distinguished by thickness. In other words, the “sheet” in this specification includes a thin film-like material, and the “film” in this specification includes a thick sheet-like material.
Further, in this specification, “(meth) acrylic copolymer” includes “acrylic copolymer”, “methacrylic copolymer”, and “acrylic-methacrylic copolymer”. Yes, “(meth) acryloyl” means “acryloyl” and “methacryloyl”, and “(meth) acryl” means “acryl” and “methacryl”.

  FIG. 1 is a schematic cross-sectional view of a solar cell module according to the present invention. The solar cell module 100 includes a solar cell surface protective material (I), a light receiving surface side sealing material (II), a solar battery cell (III), a non-light receiving surface side sealing material (IV), and a solar cell back surface protection. It has at least material (V). The light receiving surface side of the solar battery cell (III) is protected by the solar cell surface protecting material (I) through the sealing material (II) on the light receiving surface side. On the other hand, the non-light-receiving surface side of the solar battery cell (III) is protected by the solar battery back surface protective material (V) through the non-light-receiving surface side sealing material (IV).

  In addition, the easy-adhesive layer (D ') formed by the easy-adhesive for solar cell protective sheets of the present invention undergoes a crosslinking reaction using a thermocompression bonding step when forming a solar cell module. In the present invention, the easy-adhesive layer before the thermocompression bonding step is distinguished as the easy-adhesive layer (D ′), and the cross-linked easy-adhesive layer after the thermocompression bonding step is distinguished as the easy-adhesive layer (D). Similarly, the protective sheet for solar cells before the thermocompression bonding process is distinguished as a protective sheet for solar cells (Z ′), and the protective sheet after the thermocompression bonding process is classified as a protective sheet for solar cells (Z).

The easy-adhesive layer (1 ′) as the outermost surface will be described.
The easy-adhesive layer (1 ′) as the outermost surface plays a role of adhering the sealing material (II) on the light receiving surface side or the sealing material (IV) on the non-light receiving surface side and the plastic film (2). Yes.

The easy-adhesive layer (1 ′) has (meth) acrylic copolymer (A) and polyisocyanate compound (B) as essential components,
It is important that the (meth) acrylic copolymer (A) has a glass transition temperature of 10 to 100 ° C., a number average molecular weight of 15,000 to 250,000, and a hydroxyl value of 2 to 100 (mgKOH / g). It is.

When the glass transition temperature of the (meth) acrylic copolymer (A) exceeds 100 ° C., the coating film of the easy-adhesive agent becomes hard and the adhesive force to the sealing material decreases. When the temperature is lower than 10 ° C., tackiness occurs on the surface of the coating film of the easy-adhesive agent. Therefore, when the solar cell protective sheet is formed into a roll after production, blocking is likely to occur. The glass transition temperature of the (meth) acrylic copolymer (A) is preferably 10 to 80 ° C, and more preferably 20 to 70 ° C.
The glass transition temperature here is a glass transition temperature measured by differential scanning calorimetry (DSC) for a resin obtained by drying the (meth) acrylic copolymer (A) to a solid content of 100%. Indicates. For example, for the glass transition temperature, an aluminum pan containing a sample obtained by weighing about 10 mg of a sample and an aluminum pan containing no sample are set in a DSC apparatus, and this is set to −50 using liquid nitrogen in a nitrogen stream. A rapid cooling treatment is performed until the temperature is increased to 200 ° C. at 20 ° C./min, and a DSC curve is plotted. The slope of the DSC curve on the low temperature side (the DSC curve portion in the temperature region where no transition or reaction occurs in the test piece) is extended to the high temperature side, and the slope of the step change portion of the glass transition is maximized. From the intersection with the tangent drawn at such a point, the extrapolated glass transition start temperature (Tig) can be determined, and this can be determined as the glass transition temperature. The glass transition temperature of this invention has described the value measured by said method.

When the number average molecular weight of the (meth) acrylic copolymer (A) exceeds 250,000, the adhesive force to the sealing material is reduced. The wet heat resistance of the film is lowered, and the adhesive force to the sealing material is lowered after the wet heat test.
In addition, said number average molecular weight is the value of polystyrene conversion by the gel permeation chromatography (GPC) of a (meth) acrylic-type copolymer (A). For example, the temperature of the columns (KF-805L, KF-803L, and KF-802 manufactured by Showa Denko KK) is 40 ° C., THF is used as the eluent, the flow rate is 0.2 ml / min, and the detection is RI. The sample concentration was 0.02%, and polystyrene was used as a standard sample. The number average molecular weight of the present invention describes the value measured by the above method.

  It is important that the hydroxyl value of the (meth) acrylic copolymer (A) is 2 to 100 mgKOH / g in terms of solid content, preferably 2 to 50 mgKOH / g, and more preferably 2 to 30 mgKOH / g. It is more preferable. When the hydroxyl value of the (meth) acrylic copolymer (A) exceeds 100 mgKOH / g, the cross-linking of the easy-adhesive coating film becomes dense, and the adhesive force to the plastic film (2) decreases. Even if it is initially bonded, the crosslinking reaction may proceed during the moist heat test, and the adhesive strength may decrease after the moist heat test. On the other hand, in the case of less than 2 mgKOH / g, the cross-linking of the easy-adhesive coating film is sparse, the wet heat resistance of the coating film is lowered, and the adhesive force to the sealing material is lowered after the wet heat test.

The easy-adhesive layer (1 ′) of the present invention contains a carbon-carbon double bond derived from a (meth) acryloyl group in an amount specified in the range of iodine value of 0.01 to 50 (g / 100 g). It is characterized by this, Preferably it is 0.1-30 (g / 100g), More preferably, it is the range of 0.5-20 (g / 100g). When the iodine value is larger than 50 (g / 100 g), the crosslinking reaction of the easy-adhesive agent becomes excessive and the adhesive force is reduced. On the other hand, when the ratio is smaller than 0.01 (g / 100 g), the crosslinking reaction is insufficient and sufficient adhesive strength cannot be obtained.
Here, the iodine value can be determined by the following measuring method.
A sample of 0.3 to 1 g is weighed in an Erlenmeyer flask to the order of 0.1 mg, and left in a constant temperature water bath at 25 ° C. for 30 minutes. Take out the Erlenmeyer flask from the thermostatic water bath, add 25 cm ³ of the Wiis solution using a pipette, cap and shake lightly until uniform, and then leave it in a thermostatic water bath at 25 ° C. for 120 minutes. Remove the Erlenmeyer flask from the thermostatic water bath, add 10 cm ³ of a potassium iodide aqueous solution with a concentration of 100 g / L, cap and shake vigorously. Next, it titrates using 0.1 mol / L sodium thiosulfate aqueous solution. When the upper water tank is a little yellow, add 1 cm ³ starch solution and continue titration until the purple color of the solution disappears.
The iodine value is determined by the following formula. The hydroxyl value is a value converted to the solid content of the easy-adhesive (unit: g / 100 g).
Iodine number (g / 100g)
= [{(V0−V1) × c × 12.69} / m] / (solid content concentration / 100)
Where m is the amount of sample collected (g)
V0: titration of blank test (cm ³ )
V1: Titrate of the material (cm ³ )
c: Concentration of sodium thiosulfate solution (mol / L)
The iodine value of this invention has described the value measured by said method.

The Wiis solution used for the titration of iodine value is prepared according to the following procedure.
4.8-5.2 g of iodine trichloride is weighed to the nearest 0.1 g and placed in a 1 L brown bottle with a stopper coated with polytetrafluoroethylene. In a 1 L Erlenmeyer flask with a stopper, 5.5 g of iodine is weighed to a unit of 0.1 g, and 640 cm ³ of acetic acid is added and dissolved. This solution is added to a brown bottle containing iodine trichloride and mixed to make a Wies solution. In the present invention, after preparation of the solution, it was stored in a cool and dark place and used within 30 days after preparation of the solution.

The sealing material (II) positioned on the light receiving surface side of the solar battery cell (III) and the sealing material (IV) positioned on the non-light receiving surface side are not particularly limited, and known materials can be suitably applied. Suitable materials include EVA (ethylene-vinyl acetate copolymer), polyvinyl butyral, polyurethane, polyolefin and the like. Of these, EVA is mainly used from the viewpoint of cost. As the sealing materials (II) and (IV), a sheet (including a film) is simple, but a paste or the like may be used.
The sealing material (II) located on the light receiving surface side and the sealing material (IV) located on the non-light receiving surface side may contain an organic peroxide. By containing an organic peroxide, when the solar battery cell (III) is sandwiched between the sealing materials (II) and (IV) and heated, the sealing material (II) is crosslinked or sealed by a radical reaction. The material (II) and the sealing material (IV) can be crosslinked, or the sealing material (IV) can be crosslinked with high efficiency.
By including an organic peroxide in the sealing material (II) on the light-receiving surface side or the sealing material (IV) on the non-light-receiving surface side, an easy-adhesive layer (D before curing) is applied during heat sealing. ') The organic peroxide also acts on the carbon-carbon double bond in it, and the sealing material (II) on the light receiving surface side or the sealing material (IV) on the non-light receiving surface side and the easy-adhesive before curing It is considered that the layer (D ′) is crosslinked or the easy-adhesive layer (D ′) before the curing treatment is crosslinked.
Therefore, in the present invention, the carbon-carbon double bond refers to a carbon-carbon double bond site (C = C) that can be polymerized with each other by radical reaction activity, and is a reaction such as a benzene ring or a pyridine ring. This is not the case with inert carbon-carbon double bonds. Among them, a highly reactive carbon-carbon double bond such as a (meth) acryloyl group is important, and a carbon-carbon double bond such as a vinyl group is extremely inferior in reactivity. The “curing treatment” in the present specification refers to a treatment for bonding the encapsulant (II, IV) and the solar cell protective sheet (Z) and then bonding them.

As a method for causing the easy adhesive layer of the present invention to contain a carbon-carbon double bond derived from a (meth) acryloyl group in an amount specified in the range of iodine value of 0.1 to 50 (g / 100 g), Various methods are possible,
(1) Contains an acrylic copolymer (A1) having a carbon-carbon double bond derived from a (meth) acryloyl group,
(2) containing an acrylic copolymer (A2) having no (meth) acryloyl group and a compound (C) having a (meth) acryloyl group,
The method is preferably mentioned.

Examples of the (meth) acrylic copolymer (A1) having a carbon-carbon double bond derived from such a (meth) acryloyl group include the following (meth) acrylic copolymers (A1-1) to ( A1-4).
The (meth) acrylic copolymer (A1-1) includes a (meth) acrylic monomer (a1) having a glycidyl group, a (meth) acrylic monomer (a2) having a hydroxyl group, a glycidyl group, a hydroxyl group, and a carboxyl group. A (meth) acrylic monomer (a3) having a carboxyl group is reacted with a glycidyl group in a side chain in a copolymer having a (meth) acrylic monomer (a4) having no group as a constituent unit. It is a (meth) acrylic copolymer.
That is, a (meth) acrylic monomer (a1) having a glycidyl group, a (meth) acrylic monomer (a2) having a hydroxyl group, and a (meth) acrylic monomer (a4 having no glycidyl group, hydroxyl group or carboxyl group) ) And then the (meth) acrylic monomer (a3) having a carboxyl group is reacted with all or part of the glycidyl groups in the side chain in the copolymer pair. Thus, the side chain of the carbon-carbon double bond can be introduced starting from the glycidyl group.

The (meth) acrylic copolymer (A1-2) is a copolymer obtained by introducing a side chain of a carbon-carbon double bond with a carboxyl group as a base point. That is, the (meth) acrylic copolymer (A2) includes a (meth) acrylic monomer (a3) having a carboxyl group, a (meth) acrylic monomer (a2) having a hydroxyl group, a glycidyl group, a hydroxyl group, and a carboxyl group. A (meth) acrylic monomer (a1) having a glycidyl group is reacted with a carboxyl group in a copolymer having a (meth) acrylic monomer (a4) having no group as a structural unit (meth) Acrylic copolymer.
As in the case of the (meth) acrylic copolymer (A1), when introducing a side chain of a carbon-carbon double bond, a glycidyl group can be reacted with all or part of the carboxyl group.

  The (meth) acrylic copolymer (A1-3) is a copolymer comprising a (meth) acrylic monomer (a2) having a hydroxyl group and a (meth) acrylic monomer (a6) having no hydroxyl group as structural units. This is a (meth) acrylic copolymer obtained by reacting a part of the hydroxyl group in the polymer with a (meth) acrylic monomer (a5) having an isocyanate group.

  The (meth) acrylic copolymer (A1-4) comprises maleic anhydride, a (meth) acrylic monomer (a2) having a hydroxyl group, and a (meth) acrylic monomer (a6) having no hydroxyl group. A (meth) acrylic copolymer obtained by reacting a hydroxyl group-containing (meth) acrylic monomer (a2) with an acid anhydride group in a copolymer as a constituent unit.

  Examples of the (meth) acrylic monomer (a1) having a glycidyl group include glycidyl acrylate, glycidyl methacrylate, and 4-hydroxybutyl acrylate glycidyl ether.

Examples of the (meth) acrylic monomer (a2) having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. The hydroxyl group derived from the (meth) acrylic monomer (a2) having a hydroxyl group reacts with the polyisocyanate compound (B) described later, and is an easy adhesive which is a cured product of the easy adhesive layer (D ′) before the curing treatment. Responsible for forming the layer (D).
Moreover, in this invention, monomers other than the (meth) acrylic-type monomer (a2) which has a hydroxyl group are defined as the (meth) acrylic-type monomer (a6) which does not have a hydroxyl group.

  Examples of the (meth) acrylic monomer (a3) having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, and citraconic acid.

Monomers other than the (meth) acrylic monomer (a1) having the glycidyl group, the (meth) acrylic monomer (a2) having a hydroxyl group, and the (meth) acrylic monomer (a3) having a carboxyl group are also used as glycidyl groups. It is defined as a (meth) acrylic monomer (a4) having neither a hydroxyl group nor a carboxyl group.
As the (meth) acrylic monomer (a4) having no glycidyl group, hydroxyl group or carboxyl group, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate , Tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, and the like.

  Examples of the (meth) acrylic monomer (a5) having an isocyanate group include 2-isocyanatoethyl acrylate and 2-isocyanatoethyl methacrylate. These products include Karenz AOI and Karenz manufactured by Showa Denko K.K. There are MOI.

  In addition to (meth) acrylic monomers (a1) to (a6), vinyl acetate, vinyl ether, vinyl propionate, styrene and the like are also used to form (meth) acrylic copolymers (A1-1) to (A1-4). Can be used as appropriate.

First stage of formation of (meth) acrylic copolymer (A1-1): stage of polymerizing (meth) acrylic monomer (a1) (a2) (a4), (meth) acrylic copolymer (A1) -2) First stage of formation: (meth) acrylic monomer (a3) (a2) (a4) polymerization stage, (meth) acrylic copolymer (A1-3) formation first stage: (Meth) acrylic monomer (a2) (a6) polymerization stage, (meth) acrylic copolymer (A1-4) formation first stage: maleic anhydride and (meth) acrylic monomer (a2) The step of polymerizing (a6) can be performed by a normal radical polymerization reaction. There is no limitation on the reaction method, and it can be carried out by a known polymerization method such as solution polymerization, bulk polymerization, emulsion polymerization, etc., but solution polymerization is preferable because the control of the reaction is easy and the next operation can be directly performed. .
The solvent is not particularly limited as long as the resin of the present invention dissolves, such as methyl ethyl ketone, methyl isobutyl ketone, toluene, cellosolve, ethyl acetate, and butyl acetate, and may be used alone or in combination with a plurality of solvents. Also known as polymerization initiators used in the polymerization reaction are organic peroxides such as benzoyl peroxide, acetyl peroxide, methyl ethyl ketone peroxide, lauroyl peroxide, and azo initiators such as azobisisobutyronitrile. There is no particular limitation. Further, in each case of the (meth) acrylic copolymers (A1-1) to (A1-4), for example, only one type or a plurality of types may be used as the (meth) acrylic monomer (a2). These compounds may be used in combination. The same applies to the (meth) acrylic monomers (a1) and (a3) to (a6).

  As the acrylic copolymer (A2) having no (meth) acryloyl group, the one in the first stage of the formation of the (meth) acrylic copolymer (A1-1) corresponds, and is exemplified above (meta ) It can be obtained by radical polymerization reaction of acrylic monomers (a1) to (a6), vinyl acetate, vinyl ether, vinyl propionate, styrene and the like.

Next, the compound (C) having a (meth) acryloyl group will be described.
The compound (C) having a (meth) acryloyl group used in the present invention may be any compound as long as it has at least one (meth) acryloyl group in the molecule, such as trimethylolpropane. (Meth) acrylates of polyhydric alcohols such as tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, bisphenol A diglycidyl ether di ( Examples thereof include epoxy (meth) acrylates such as (meth) acrylate and di (meth) acrylate of polyethylene glycol diglycidyl ether.
Among these, from the viewpoint of reactivity, the compound (C) having a (meth) acryloyl group preferably has 2 or more (meth) acryloyl groups in the molecule, and more preferably 3 or more in the molecule. Is preferred.
Moreover, as a compound (C) which has a (meth) acryloyl group, it is hydroxyl to such an extent that the bridge | crosslinking of the acrylic copolymer (A-2) which does not have a (meth) acryloyl group, and a polyisocyanate compound (B) is inhibited. Group and other functional groups may be included.

The organic peroxide contained in the sealing material is preferably used in an amount of 0.05 to 3.0 parts by weight with respect to 100 parts by weight of the resin of the sealing material. Specific examples of the organic peroxide include tert-butyl peroxyisopropyl carbonate, tert-butyl peroxy-2-ethylhexyl isopropyl carbonate, tert-butyl peroxyacetate, tert-butylcumyl peroxide, 2,5-dimethyl- 2,5-di (tert-butylperoxy) hexane, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3,2,5-dimethyl- 2,5-di (tert-butylperoxy) hexane, 1,1-di (tert-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di (tert-butylperoxy) cyclohexane, 1,1-di (tert-hexylperoxy) cyclohex 1,1-di (tert-amylperoxy) cyclohexane, 2,2-di (tert-butylperoxy) butane, methyl ethyl ketone peroxide, 2,5-dimethylhexyl-2,5-diperoxybenzoate, tert-butyl hydroperoxide, dibenzoyl peroxide, p-chlorobenzoyl peroxide, tert-butyl peroxyisobutyrate, n-butyl-4,4-di (tert-butylperoxy) valerate, ethyl-3, 3-di (tert-butylperoxy) butyrate, hydroxyheptyl peroxide, dichlorohexanone peroxide, 1,1-di (tert-butylperoxy) 3,3,5-trimethylcyclohexane, n-butyl-4,4 -Di (tert-butyl peroxy) ) Valerate, 2,2-di (tert- butylperoxy) butane, and the like. These organic peroxides can be contained in the encapsulant, for example, by adding a resin of the encapsulant when the sheet is processed and melt kneading.

  The compound (C) having a (meth) acryloyl group is contained at a ratio of 0.1 to 20 parts by weight with respect to 100 parts by weight of the acrylic copolymer (A-2) having no (meth) acryloyl group. It is preferably 0.5 to 15 parts by weight, more preferably 1 to 10 parts by weight. When the proportion is less than 0.1 parts by weight, a sufficient effect of improving the adhesive strength cannot be expected. When the proportion is more than 20 parts by weight, the cross-linking between the compounds (C) having a (meth) acryloyl group becomes dense. Adhesive strength to materials and sealing materials is reduced.

Next, the polyisocyanate compound (B) will be described.
The polyisocyanate compound (B) reacts with a hydroxyl group in the (meth) acrylic copolymer (A) to crosslink the copolymers, thereby imparting moisture and heat resistance to the easy-adhesive layer, and a solar cell. Improving adhesion to a sealing material such as EVA, which is a plastic film (2) constituting the protective sheet for use, a sealing material (II) on the light-receiving surface side, or a sealing material (IV) on the non-light-receiving surface side Can do. Therefore, it is important that the polyisocyanate compound (B) has two or more isocyanate groups in one molecule, and examples thereof include aromatic polyisocyanates, chain aliphatic polyisocyanates, and alicyclic polyisocyanates. It is done. The polyisocyanate compound (B) may be used alone or in combination of two or more compounds.

  Aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-triisocyanate. Range isocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4 ', 4 " -Triphenylmethane triisocyanate etc. can be mentioned.

  Examples of chain aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, and dodeca. Examples include methylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate.

  Examples of alicyclic polyisocyanates include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl- Examples include 2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4′-methylene bis (cyclohexyl isocyanate), 1,4-bis (isocyanate methyl) cyclohexane and the like.

  In addition to the polyisocyanate, an adduct of the polyisocyanate and a polyol compound such as trimethylolpropane, a burette or isocyanurate of the polyisocyanate, and further, the polyisocyanate and a known polyether polyol or polyester polyol, Examples thereof include adducts with acrylic polyol, polybutadiene polyol, polyisoprene polyol and the like.

  Among these polyisocyanate compounds (B), a low-yellowing type aliphatic or alicyclic polyisocyanate is preferable from the viewpoint of design, and an isocyanurate is preferable from the viewpoint of heat-and-moisture resistance. More specifically, an isocyanurate form of hexamethylene diisocyanate (HDI) and an isocyanurate form of 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI) are preferred.

  Furthermore, the blocked polyisocyanate compound (B1) can be obtained by reacting almost all of the isocyanate groups of the polyisocyanate compound (B) with the blocking agent. The easy-adhesive layer (D ′) before the curing treatment obtained by applying the easy-adhesive for solar cell protective sheets in the present invention is bonded to the sealing material (II, IV) to produce a solar cell module. The polyisocyanate compound (B) is preferably a blocked polyisocyanate compound (B1).

  Examples of the blocking agent include phenols such as phenol, thiophenol, methylthiophenol, xylenol, cresol, resorcinol, nitrophenol, chlorophenol, oximes such as acetone oxime, methyl ethyl ketone oxime, cyclohexanone oxime, methanol, ethanol, n- Alcohols such as propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, t-butyl alcohol, t-pentanol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, benzyl alcohol , Pyrazol such as 3,5-dimethylpyrazole, 1,2-pyrazole, etc. , Triazoles such as 1,2,4-triazole, halogen-substituted alcohols such as ethylene chlorohydrin and 1,3-dichloro-2-propanol, ε-caprolactam, δ-valerolactam, γ-butyrolactam, β- Examples include lactams such as propyl lactam, and active methylene compounds such as methyl acetoacetate, ethyl acetoacetate, acetylacetone, methyl malonate, and ethyl malonate. Other examples include amines, imides, mercaptans, imines, ureas, and diaryls. One blocking agent may be used, or two or more blocking agents may be used in combination.

  Among these blocking agents, those having a dissociation temperature of 80 to 150 ° C. are preferable. When the dissociation temperature is less than 80 ° C., when the easy-adhesive is applied and the solvent is volatilized, the curing reaction proceeds and the adhesiveness to the filler may be reduced. When the dissociation temperature exceeds 150 ° C., the curing reaction does not proceed sufficiently in the vacuum thermocompression bonding step when forming the solar cell module, and the adhesion with the filler is lowered.

  Examples of the blocking agent having a dissociation temperature of 80 ° C. to 150 ° C. include methyl ethyl ketone oxime (dissociation temperature: 140 ° C., the same applies hereinafter), 3,5-dimethylpyrazole (120 ° C.), diisopropylamine (120 ° C.), and the like.

  The amount of the polyisocyanate compound (B) in the easy-adhesive agent of the present invention is within a range of 0.1 to 5 isocyanate groups with respect to one hydroxyl group of the (meth) acrylic copolymer (A). It is necessary that the amount is such that it is preferably in the range of 0.5 to 4. If it is less than 0.1, the crosslinking density is too low and the heat and moisture resistance is not sufficient, and if it is more than 5, excess isocyanate reacts with moisture in the air during the moist heat test and the coating becomes hard. Moreover, it becomes a cause of the adhesive force fall with sealing materials with the plastic film (2) which comprises the protection sheet for solar cells, EVA etc. which are sealing materials (IV) by the side of a non-light-receiving surface.

  The easy-adhesive of the present invention can contain 0.01 to 30 parts by weight, more preferably 0.1 to 10 parts by weight, of organic particles or inorganic particles described later with respect to 100 parts by weight of the solid content. Parts can be contained. By containing these particles, tackiness on the surface of the easy-adhesive layer (D ′) before the curing treatment can be reduced. If the content is less than 0.01 parts by weight, the tack on the surface of the easy-adhesive layer (D ′) before the curing treatment cannot be sufficiently reduced. On the other hand, when the amount of the various particles increases, the adhesion between the easy-adhesive layer (D ′) and the sealing material before the curing treatment may be hindered, and the adhesive force may be reduced.

  In particular, organic particles having a melting point or softening point of 150 ° C. or higher can be preferably used. If the melting point or softening point of the organic particles is lower than 150 ° C., the particles may be softened in the vacuum thermocompression bonding process when forming the solar cell module, and the adhesion with the sealing material may be hindered.

  Specific examples of the organic particles include polymethyl methacrylate resin, polystyrene resin, nylon (registered trademark) resin, melamine resin, guanamine resin, phenol resin, urea resin, silicon resin, methacrylate resin, acrylate resin and other polymer particles, Alternatively, cellulose powder, nitrocellulose powder, wood powder, waste paper powder, rice husk powder, starch and the like can be mentioned. One type of organic particles may be used, or two or more types may be used in combination.

  The polymer particles can be obtained by a polymerization method such as an emulsion polymerization method, a suspension polymerization method, a dispersion polymerization method, a soap-free polymerization method, a seed polymerization method, or a microsuspension polymerization method. The organic particles may contain impurities to the extent that the characteristics are not impaired. The shape of the particles may be any shape such as powder, granule, granule, flat plate, and fiber.

  Specific examples of inorganic particles include inorganic oxides containing metal oxides such as magnesium, calcium, barium, zinc, zirconium, molybdenum, silicon, antimony, and titanium, hydroxides, sulfates, carbonates, and silicates. System particles. Further specific examples include silica gel, aluminum oxide, calcium hydroxide, calcium carbonate, magnesium oxide, magnesium hydroxide, magnesium carbonate, zinc oxide, lead oxide, diatomaceous earth, zeolite, aluminosilicate, talc, white carbon, mica Glass fiber, glass powder, glass beads, clay, wollastonite, iron oxide, antimony oxide, titanium oxide, lithopone, pumice powder, aluminum sulfate, zirconium silicate, barium carbonate, dolomite, molybdenum disulfide, iron sand, carbon black, etc. Examples thereof include inorganic particles. One kind of inorganic particles may be used, or two or more kinds may be used in combination.

  Moreover, the said inorganic type particle | grain may contain the impurity to such an extent that the characteristic is not impaired. The shape of the particles may be any shape such as powder, granule, granule, flat plate, and fiber.

  Moreover, you may add a crosslinking accelerator to the easily adhesive in this invention in the range which does not prevent the effect by this invention as needed. The crosslinking accelerator plays a role as a catalyst for accelerating the urethane bond reaction between the hydroxyl group of the (meth) acrylic copolymer (A) and the isocyanate of the polyisocyanate compound (B). Examples of the crosslinking accelerator include tin compounds, metal salts, bases and the like. Specifically, tin octylate, dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, tin chloride, iron octylate, cobalt octylate, and naphthenic acid. Zinc, triethylamine, triethylenediamine and the like can be mentioned. These can be used alone or in combination.

  In addition, the easy-adhesive in the present invention includes, if necessary, a filler, a thixotropy imparting agent, an anti-aging agent, an antioxidant, an antistatic agent, a flame retardant, and a heat conduction, as long as the effects of the present invention are not hindered. Various additives such as property improvers, plasticizers, anti-sagging agents, antifouling agents, antiseptics, bactericides, antifoaming agents, leveling agents, curing agents, thickeners, pigment dispersants, silane coupling agents It may be added.

The easy-adhesive used in the present invention contains a solvent.
As the solvent, alcohols such as methanol, ethanol, propanol, butanol, ethylene glycol methyl ether, diethylene glycol methyl ether,
Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone,
Ethers such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether,
Hydrocarbons such as hexane, heptane, octane,
Aromatics such as benzene, toluene, xylene, cumene,
Among the esters such as ethyl acetate and butyl acetate, those suitable for the composition of the resin composition can be used, but those having a boiling point of 50 ° C. to 200 ° C. can be preferably used. When the boiling point is lower than 50 ° C., the solvent easily evaporates when applying the easy-adhesive agent, and the solid content becomes high, making it difficult to apply with a uniform film thickness. When the boiling point is higher than 200 ° C., it is difficult to dry the solvent. Two or more solvents may be used.

  The easy-adhesive agent of the present invention can be applied to the plastic film (2) to form an easy-adhesive layer (D ′), so that the sun has good adhesion to the sealing materials (II) and (IV). A protective sheet for a battery can be produced.

As a method for applying the easy-adhesive of the present invention to the plastic film (2), a conventionally known method can be used. Specific examples include comma coating, gravure coating, reverse coating, roll coating, lip coating, and spray coating. The easy-adhesive layer (D ′) before the curing treatment can be formed by applying the easy-adhesive by these methods and volatilizing the solvent by heat drying.
The thickness of the easy-adhesive layer (D ′) before the curing treatment is preferably 0.01 to 30 μm, and more preferably 0.1 to 10 μm.

  The plastic film (2) of the present invention will be described.

  The plastic film (2) used for the protective sheet for solar cells of the present invention is made of a polyester resin having an intrinsic viscosity of 0.6 (dl / g) or more and a cyclic trimer content of 1% by weight or less. Polyester film. The intrinsic viscosity is preferably 0.6 to 1.2 (dl / g). Further, the cyclic trimer content is preferably as small as possible, but more preferably 0.5% by weight or less.

Since the protective sheet for solar cells maintains insulation, a thick film is required, and a polyester film is mainly used as a base material due to cost requirements.
A polyester resin having an intrinsic viscosity of 0.6 (dl / g) or more and a cyclic trimer content of 1% by weight or less can be obtained by a solid phase polymerization method. Resin containing a large amount of cyclic trimer is likely to promote hydrolysis under high temperature and high humidity, but by controlling the cyclic trimer content to 1% by weight or less, hydrolysis under high temperature and high humidity can be suppressed. It has excellent moisture and heat resistance. The polyester film generally used has a cyclic trimer content of more than 1% by weight, so that mechanical strength is deteriorated by long-term exposure outdoors and the like, resulting in hydrolysis and cracking.

  It is important that the polyester resin as a raw material for the polyester film used in the present invention has a cyclic trimer content of 1% by weight or less, and the cyclic trimer content is 100 mg of polyester resin in 2 mL of orthochlorophenol. It is calculated | required by the method of melt | dissolving and measuring weight% with a liquid chromatography.

It is important that the polyester resin as a raw material for the polyester film used in the present invention has an intrinsic viscosity of 0.6 (dl / g) or more, and the intrinsic viscosity is obtained by the following formula.
The specific viscosity ηsp = (η / η0) −1 divided by the concentration c, and ηsp / c is extrapolated to the concentration 0.
η0: viscosity of solvent c (g / mL): concentration of resin in solvent η: viscosity of resin solution at c (g / mL) ηsp: ratio of resin solution viscosity to solvent viscosity

  The plastic film (2) may have a single layer or a multilayer structure of two or more layers. Furthermore, the vapor deposition film which vapor-deposited the metal oxide and the nonmetallic inorganic oxide may be laminated | stacked on the plastic film (2).

Examples of the metal oxide or non-metal inorganic oxide to be deposited include oxides such as silicon, aluminum, magnesium, calcium, potassium, tin, sodium, boron, titanium, lead, zirconium, and yttrium. Alkali metal and alkaline earth metal fluorides can also be used, and these can be used alone or in combination.
These metal oxides or non-metal inorganic oxides can be deposited using a conventionally known PVD method such as vacuum deposition, ion plating, sputtering, or the like, or a CVD method such as plasma CVD or microwave CVD.

When the solar cell protective sheet (Z ′) is used on the non-light-receiving surface side, the plastic film (2) constituting the solar cell protective sheet (Z ′) may be colorless, or may be a pigment or dye. A coloring component such as may be contained. When the solar cell protective sheet (Z ′) is used on the light receiving surface side, the plastic film (2) constituting the solar cell protective sheet (Z ′) is preferably colorless.
Examples of the method of containing the coloring component include a method of kneading the coloring component in advance at the time of film formation, a method of printing the coloring component on a colorless transparent film substrate, and the like. Further, a colored film and a colorless transparent film may be bonded together.

  When the solar cell protective sheet (Z ′) is used on the non-light-receiving surface side, the solar cell protective sheet is an easy-adhesive layer (2) of the plastic film (2) constituting the solar cell protective sheet (Z ′). A film layer or a coating layer such as a metal foil or a weather resistant resin layer may be provided on the surface on which D ′) is not formed.

  As the metal foil, aluminum foil, iron foil, zinc plywood and the like can be used, and among these, aluminum foil is preferable from the viewpoint of corrosion resistance. The thickness is preferably 10 μm to 100 μm, more preferably 20 μm to 50 μm. Various conventionally known adhesives can be used for laminating the metal foil.

  The weather-resistant resin layer may be a laminate of polyester resin films such as polyvinylidene fluoride film, polyethylene terephthalate, polybutylene terephthalate, polynaphthalene terephthalate, etc., using various known adhesives, or Lumiflon from Asahi Glass Co., Ltd. A coating layer formed by coating a highly weather-resistant paint such as can be used.

Next, the solar cell module will be described.
The solar cell module is a solar cell surface protection material (I) positioned on the light receiving surface side of the solar cell with respect to the solar cell (III), and is a sealing material before curing treatment positioned on the light receiving surface side of the solar cell. (II) is laminated, and the solar battery back surface protective material (V) is laminated via the sealing material (IV) before the curing treatment located on the non-light-receiving surface side of the solar battery cell, and heated at high temperature under reduced pressure. It can be obtained by pressure bonding.

Examples of the solar cell surface protective material (I) and the solar cell back surface protective material (V) include a glass plate and a plastic plate of polycarbonate or polyacrylate, at least one of which is the protective sheet for solar cell of the present invention. It is preferably formed from (Z ′).
In consideration of practical durability and flammability, the solar cell module of the present invention uses a glass plate for the solar cell surface protective material (I), and the solar cell back surface protective material (V) is the solar cell of the present invention. It is preferably formed from a protective sheet (Z ′).

  Sealing materials such as EVA used as sealing materials (II) and (IV) include UV absorbers for improving weather resistance, light stabilizers, and organic peroxides for crosslinking EVA itself. The additive may be contained.

  The easy-adhesive layer (D ′) of the present invention is formed with the sealing materials (II) and (IV) by crosslinking the carbon-carbon double bond in the high-temperature thermocompression bonding step when forming the solar cell module. There is an effect of improving adhesive strength. When the organic peroxide is contained in the sealing materials (II) and (IV), this crosslinking reaction is promoted, so that the effect of the present invention is maximized. Therefore, it is preferable that the sealing materials (II) and (IV) located on the non-light-receiving surface side contain an organic peroxide.

  As the solar cell (III), an electrode is provided on a photoelectric conversion layer such as crystalline silicon, amorphous silicon, and a compound semiconductor represented by copper indium selenide, and further, these are laminated on a substrate such as glass. Etc. can be illustrated.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by a following example. In the examples, “part” means “part by weight” and “%” means “% by weight”. Tables 1 and 2 show the physical properties of the (meth) acrylic copolymers.

<(Meth) acrylic copolymer A1 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube, 18 parts of methyl methacrylate, 78 parts of n-butyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, 2 parts of glycidyl methacrylate, and 100 parts of toluene The temperature was raised to 100 ° C. while stirring and stirring in a nitrogen atmosphere. Next, 0.15 part of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours, then 0.07 part of azobisisobutyronitrile was added to conduct a polymerization reaction for another 2 hours, and then 0.07 part was further added. A part of azobisisobutyronitrile was added and the polymerization reaction was further carried out for 2 hours.
Thereafter, 0.03 part of hydroquinone, 0.8 part of dimethylbenzylamine and 1 part of acrylic acid (the amount required for modification of glycidyl methacrylate: 2 parts) were added, and the mixture was heated and stirred at 100 ° C. for 15 hours. It was confirmed that the acid value was 2 or less, the number average molecular weight was 39,000, the hydroxyl value was 17.2 (mgKOH / g), Tg was 30 ° C., iodine value was 3.6 (g / 100 g), solid A 50% (meth) acrylic copolymer A1 solution was obtained.

  The number average molecular weight, glass transition temperature, acid value, hydroxyl value, and iodine value were measured as described below.

<Measurement of number average molecular weight (Mn)>
Mn was measured by GPC (gel permeation chromatography) described above.

<Measurement of glass transition temperature (Tg)>
The glass transition temperature was measured by the differential scanning calorimetry (DSC) method described above.
In addition, the sample for Tg measurement used what heated said acrylic resin solution at 150 degreeC for about 15 minutes, and was made to dry.

<Measurement of acid value (AV)>
About 1 g of a sample (resin solution: about 50%) is accurately weighed in a stoppered Erlenmeyer flask, and 100 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixed solution is added and dissolved. To this is added phenolphthalein reagent as an indicator and held for 30 seconds. Thereafter, the solution is titrated with a 0.1N alcoholic potassium hydroxide solution until the solution becomes light red. The acid value was determined by the following formula. The acid value was a numerical value of the dry state of the resin (unit: mgKOH / g).
Acid value (mgKOH / g) = {(5.611 × a × F) / S} / (Nonvolatile content concentration / 100)
Where S: Amount of sample collected (g)
a: Consumption of 0.1N alcoholic potassium hydroxide solution (ml)
F: Potency of 0.1N alcoholic potassium hydroxide solution

<Measurement of hydroxyl value (OHV)>
About 1 g of a sample (resin solution: about 50%) is accurately weighed in a stoppered Erlenmeyer flask, and 100 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixed solution is added and dissolved. Further, exactly 5 ml of an acetylating agent (a solution in which 25 g of acetic anhydride was dissolved in pyridine to make a volume of 100 ml) was added and stirred for about 1 hour. To this, phenolphthalein reagent is added as an indicator and lasts for 30 seconds. Thereafter, the solution is titrated with a 0.1N alcoholic potassium hydroxide solution until the solution becomes light red.
The hydroxyl value was determined by the following formula. The hydroxyl value was a numerical value in the dry state of the resin (unit: mgKOH / g).
Hydroxyl value (mgKOH / g)
= [{(B−a) × F × 28.25} / S] / (Nonvolatile content concentration / 100) + D
Where S: Amount of sample collected (g)
a: Consumption of 0.1N alcoholic potassium hydroxide solution (ml)
b: Consumption of 0.1N alcoholic potassium hydroxide solution in the empty experiment (ml)
F: Potency of 0.1N alcoholic potassium hydroxide solution D: Acid value (mgKOH / g)

<Measurement of iodine value>
The iodine value was determined by the titration method described above.

<(Meth) acrylic copolymer A2 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube, 18 parts of methyl methacrylate, 78 parts of n-butyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, 2 parts of glycidyl methacrylate, and 100 parts of toluene The temperature was raised to 100 ° C. while stirring in a nitrogen atmosphere, and 0.40 part of azobisisobutyronitrile was added to carry out the polymerization reaction for 2 hours. Next, 0.05 part of azobisisobutyronitrile was added. In addition, the polymerization reaction was further performed for 2 hours, and 0.05 part of azobisisobutyronitrile was further added to perform the polymerization reaction for another 2 hours.
Thereafter, 0.03 part of hydroquinone, 0.8 part of dimethylbenzylamine and 1 part of acrylic acid (the amount required for modification of glycidyl methacrylate: 2 parts) were added, and the mixture was heated and stirred at 100 ° C. for 15 hours. It was confirmed that the acid value was 2 or less, the number average molecular weight was 16,000, the hydroxyl value was 16.5 (mgKOH / g), the Tg was 30 ° C., the iodine value was 3.6 (g / 100 g), solid A 50% (meth) acrylic copolymer A2 solution was obtained.

<(Meth) acrylic copolymer A3 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube, 18 parts of methyl methacrylate, 78 parts of n-butyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, 2 parts of glycidyl methacrylate, and 100 parts of toluene The temperature was raised to 80 ° C. while stirring in a nitrogen atmosphere, 0.075 part of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours, and then 0.07 part of azobisisobutyronitrile was added. In addition, the polymerization reaction was further performed for 2 hours, and 0.07 part of azobisisobutyronitrile was further added to perform the polymerization reaction for another 2 hours.
Thereafter, 0.03 part of hydroquinone, 0.8 part of dimethylbenzylamine and 1 part of acrylic acid (the amount required for modification of glycidyl methacrylate: 2 parts) were added, and the mixture was heated and stirred at 100 ° C. for 15 hours. It was confirmed that the acid value was 2 or less, the number average molecular weight was 75,000, the hydroxyl value was 18.0 (mgKOH / g), the Tg was 30 ° C., the iodine value was 3.6 (g / 100 g), solid A 50% (meth) acrylic copolymer A3 solution was obtained.

<(Meth) acrylic copolymer A4 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen inlet tube was charged with 40 parts of methyl methacrylate, 56 parts of n-butyl methacrylate, 4 parts of 2-hydroxylethyl methacrylate, and 100 parts of toluene under a nitrogen atmosphere. The temperature was raised to 100 ° C. with stirring at 0.15 parts, 0.15 parts of azobisisobutyronitrile was added and the polymerization reaction was carried out for 2 hours, and then 0.07 parts of azobisisobutyronitrile was added, and another 2 hours. A polymerization reaction was carried out, 0.07 part of azobisisobutyronitrile was further added, and the polymerization reaction was further carried out for 2 hours.
Thereafter, 0.03 part of hydroquinone and 0.03 part of dibutyltin dilaurate were added, and 2-isocyanatoethyl methacrylate: 1.7 parts (of the above-mentioned 2-hydroxylethyl methacrylate: 4 parts, about 2 parts were modified) What was dissolved in 1.7 parts of methyl ethyl ketone was added dropwise over 2 hours with stirring at 40 ° C. It was confirmed by IR that the isocyanate peak (2260 cm ⁻¹ ) had disappeared, the number average molecular weight was 38,000, the hydroxyl value was 8.6 (mgKOH / g), the Tg was 50 ° C., and the iodine value was 3.9 (g / 100 g), a (meth) acrylic copolymer A4 solution having a solid content of 50% was obtained.

<(Meth) acrylic copolymer A5 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 18 parts of methyl methacrylate, 78 parts of n-butyl methacrylate, 4 parts of 2-hydroxylmethacrylate, and 100 parts of toluene, under a nitrogen atmosphere. The temperature was raised to 100 ° C. with stirring at 0.15 parts, 0.15 parts of azobisisobutyronitrile was added and the polymerization reaction was carried out for 2 hours, and then 0.07 parts of azobisisobutyronitrile was added, and another 2 hours. A polymerization reaction was carried out, 0.07 part of azobisisobutyronitrile was further added, and the polymerization reaction was further carried out for 2 hours.
Thereafter, 0.03 part of hydroquinone and 0.03 part of dibutyltin dilaurate were added, and 2-isocyanatoethyl methacrylate: 2.9 parts (about 3.5 parts of the above-mentioned 2-hydroxylethyl methacrylate: 4 parts The amount required for modification) dissolved in 2.9 parts of methyl ethyl ketone was added dropwise over 2 hours with stirring at 40 ° C. It was confirmed by IR that the isocyanate peak (2260 cm ⁻¹ ) had disappeared, the number average molecular weight was 33,000, the hydroxyl value was 2.1 (mgKOH / g), the Tg was 27 ° C., and the iodine value was 6.9 (g / 100 g), a (meth) acrylic copolymer A5 solution having a solid content of 50% was obtained.

<(Meth) acrylic copolymer A6 solution>
In a four-necked flask equipped with a condenser, a stirrer, a thermometer, and a nitrogen inlet tube, 18 parts of methyl methacrylate, 78 parts of n-butyl methacrylate, 2 parts of 2-hydroxylmethacrylate, 2 parts of phthalic anhydride, 100 parts of toluene The mixture was heated to 100 ° C. with stirring under a nitrogen atmosphere, 0.15 part of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours, and then 0.07 of azobisisobutyronitrile was added. The polymerization reaction was further carried out for 2 hours, and 0.07 part of azobisisobutyronitrile was further added to carry out the polymerization reaction for another 2 hours. Thereafter, 0.85 part of 2-hydroxyethyl methacrylate (the amount required for modification of phthalic anhydride: 2 parts) and 0.5 part of triethylamine were added, and the mixture was heated and stirred at 110 ° C. for 7 hours. (Meth) acrylic copolymer A6 solution having a molecular weight of 36,000, a hydroxyl value of 8.5 (mgKOH / g), a Tg of 30 ° C., an iodine value of 5.1 (g / 100 g), and a solid content of 50% Got.

<(Meth) acrylic copolymer A7 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen inlet tube, 96 parts of n-butyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, 2 parts of glycidyl methacrylate, and 100 parts of toluene were charged, and under a nitrogen atmosphere The temperature was raised to 100 ° C. with stirring at 0.15 parts, 0.15 parts of azobisisobutyronitrile was added and the polymerization reaction was carried out for 2 hours, and then 0.07 parts of azobisisobutyronitrile was added, and another 2 hours. A polymerization reaction was carried out, 0.07 part of azobisisobutyronitrile was further added, and the polymerization reaction was further carried out for 2 hours.
Thereafter, 0.03 part of hydroquinone, 0.8 part of dimethylbenzylamine and 1 part of acrylic acid (the amount required for modification of glycidyl methacrylate: 2 parts) were added, and the mixture was heated and stirred at 100 ° C. for 15 hours. It was confirmed that the acid value was 2 or less, the number average molecular weight was 38,000, the hydroxyl value was 17.0 (mgKOH / g), Tg was 20 ° C., iodine value was 3.5 (g / 100 g), solid A 50% (meth) acrylic copolymer A7 solution was obtained.

<(Meth) acrylic copolymer A8 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube, 90 parts of methyl methacrylate, 6 parts of n-butyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, 2 parts of glycidyl methacrylate, and 100 parts of toluene The temperature was raised to 100 ° C. with stirring in a nitrogen atmosphere, 0.15 part of azobisisobutyronitrile was added and the polymerization reaction was carried out for 2 hours, and then 0.07 part of azobisisobutyronitrile was added. In addition, the polymerization reaction was further performed for 2 hours, and 0.07 part of azobisisobutyronitrile was further added to perform the polymerization reaction for another 2 hours.
Thereafter, 0.03 part of hydroquinone, 0.8 part of dimethylbenzylamine and 1 part of acrylic acid (the amount required for modification of glycidyl methacrylate: 2 parts) were added, and the mixture was heated and stirred at 100 ° C. for 15 hours. It was confirmed that the acid value was 2 or less, the number average molecular weight was 41,000, the hydroxyl value was 17.0 (mgKOH / g), the Tg was 96 ° C., the iodine value was 3.6 (g / 100 g), solid A 50% (meth) acrylic copolymer A8 solution was obtained.

<(Meth) acrylic copolymer A9 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube, 20 parts of methyl methacrylate, 63 parts of n-butyl methacrylate, 15 parts of 2-hydroxyethyl methacrylate, 2 parts of glycidyl methacrylate, and 100 parts of toluene The temperature was raised to 100 ° C. with stirring in a nitrogen atmosphere, 0.15 part of azobisisobutyronitrile was added and the polymerization reaction was carried out for 2 hours, and then 0.07 part of azobisisobutyronitrile was added. In addition, the polymerization reaction was further performed for 2 hours, and 0.07 part of azobisisobutyronitrile was further added to perform the polymerization reaction for another 2 hours.
Thereafter, 0.03 part of hydroquinone, 0.8 part of dimethylbenzylamine and 1 part of acrylic acid (the amount required for modification of glycidyl methacrylate: 2 parts) were added, and the mixture was heated and stirred at 100 ° C. for 15 hours. It was confirmed that the acid value was 2 or less, the number average molecular weight was 45,000, the hydroxyl value was 73.0 (mgKOH / g), Tg was 40 ° C., iodine value was 3.6 (g / 100 g), solid A 50% (meth) acrylic copolymer A9 solution was obtained.

<(Meth) acrylic copolymer A10 solution>
In a four-necked flask equipped with a condenser, a stirrer, a thermometer, and a nitrogen inlet tube, 45 parts of methyl methacrylate, 38 parts of n-butyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, 15 parts of glycidyl methacrylate, and 100 parts of toluene The temperature was raised to 100 ° C. with stirring in a nitrogen atmosphere, 0.15 part of azobisisobutyronitrile was added and the polymerization reaction was carried out for 2 hours, and then 0.07 part of azobisisobutyronitrile was added. In addition, the polymerization reaction was further performed for 2 hours, and 0.07 part of azobisisobutyronitrile was further added to perform the polymerization reaction for another 2 hours.
Thereafter, 0.03 part of hydroquinone, 0.8 part of dimethylbenzylamine and 7.5 parts of acrylic acid (the amount required for modification of glycidyl methacrylate: 15 parts) were added, and the mixture was heated and stirred at 100 ° C. for 15 hours. . It was confirmed that the acid value was 2 or less, the number average molecular weight was 37,000, the hydroxyl value was 8.3 (mgKOH / g), the Tg was 57 ° C., the iodine value was 27.4 (g / 100 g), solid A 52% (meth) acrylic copolymer A10 solution was obtained.

<(Meth) acrylic copolymer A11 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube, 19.5 parts of methyl methacrylate, 78 parts of n-butyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, 0.5 part of glycidyl methacrylate, Charge 100 parts of toluene, raise the temperature to 100 ° C. with stirring in a nitrogen atmosphere, add 0.06 parts of azobisisobutyronitrile, conduct a polymerization reaction for 2 hours, and then add azobisisobutyronitrile. 0.05 part was added and the polymerization reaction was further performed for 2 hours, and 0.05 part of azobisisobutyronitrile was further added and the polymerization reaction was further performed for 2 hours.
Thereafter, 0.03 part of hydroquinone, 0.8 part of dimethylbenzylamine and 0.25 part of acrylic acid (the amount required for the modification of glycidyl methacrylate: 0.5 part) were added and heated at 100 ° C. for 15 hours. Stir. It was confirmed that the acid value was 2 or less, the number average molecular weight was 120,000, the hydroxyl value was 10.8 (mgKOH / g), Tg was 34 ° C., iodine value was 0.8 (g / 100 g), solid A 50% (meth) acrylic copolymer A11 solution was obtained.

<(Meth) acrylic copolymer A12 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 18 parts of methyl methacrylate, 78 parts of n-butyl methacrylate, 4 parts of 2-hydroxylmethacrylate, and 100 parts of ethyl acetate, and a nitrogen atmosphere Under stirring, the temperature was raised to 77 ° C., 0.05 part of azobisisobutyronitrile was added, and a polymerization reaction was carried out for 2 hours. Next, 22 parts of ethyl acetate and 0.05 part of azobisisobutyronitrile were added to conduct a polymerization reaction for 2 hours. Further, 22 parts of ethyl acetate and 0.05 part of azobisisobutyronitrile were added. In addition, a polymerization reaction was carried out for 2 hours. Thereafter, 36 parts of ethyl acetate and 0.05 part of azobisisobutyronitrile were added to conduct a polymerization reaction for 2 hours, and 0.05 part of azobisisobutyronitrile was further added to carry out a polymerization reaction for 2 hours. .
Thereafter, 0.03 part of hydroquinone and 0.03 part of dibutyltin dilaurate were added, and 2-isocyanatoethyl methacrylate: 1.7 parts (of the above-mentioned 2-hydroxylethyl methacrylate: 4 parts, about 2 parts were modified) What was dissolved in 1.7 parts of methyl ethyl ketone was added dropwise over 2 hours with stirring at 40 ° C. It was confirmed by IR that the isocyanate peak (2260 cm ⁻¹ ) had disappeared, the number average molecular weight was 242,000, the hydroxyl value was 8.0 (mgKOH / g), Tg was 30 ° C., and the iodine value was 3.9 (g / 100 g), a (meth) acrylic copolymer A12 solution having a solid content of 35% was obtained.

<Acrylic copolymer A13 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 55 parts of methyl methacrylate, 20 parts of n-butyl methacrylate, 25 parts of 2-hydroxylmethacrylate, and 100 parts of toluene, under a nitrogen atmosphere. The temperature was raised to 100 ° C. with stirring at 0.13 parts, 0.13 parts of azobisisobutyronitrile was added and the polymerization reaction was carried out for 2 hours, and then 0.07 parts of azobisisobutyronitrile was added, and another 2 hours. A polymerization reaction was carried out, 0.07 part of azobisisobutyronitrile was further added, and the polymerization reaction was further carried out for 2 hours.
Thereafter, 0.03 part of hydroquinone and 0.03 part of dibutyltin dilaurate were added, and 2-isocyanatoethyl methacrylate: 2.9 parts (about 2 parts of the 2-hydroxyethyl methacrylate: 25 parts were modified). The amount required) dissolved in 2.9 parts of methyl ethyl ketone was added dropwise over 2 hours while stirring at 40 ° C. It was confirmed by IR that the isocyanate peak (2260 cm ⁻¹ ) had disappeared, the number average molecular weight was 45,000, the hydroxyl value was 96.4 (mgKOH / g), the Tg was 72 ° C., and the iodine value was 4.0 (g / 100 g), a (meth) acrylic copolymer A13 solution having a solid content of 50% was obtained.

<(Meth) acrylic copolymer A14 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 18 parts of methyl methacrylate, 80 parts of n-butyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, and 100 parts of toluene under a nitrogen atmosphere. The temperature was raised to 100 ° C. with stirring at 0.15 parts, 0.15 parts of azobisisobutyronitrile was added and the polymerization reaction was carried out for 2 hours, and then 0.07 parts of azobisisobutyronitrile was added, and another 2 hours. A polymerization reaction is carried out, and 0.07 part of azobisisobutyronitrile is further added to carry out the polymerization reaction for another 2 hours. The number average molecular weight is 38,000, the hydroxyl value is 8.6 (mgKOH / g), and Tg is A (meth) acrylic copolymer A14 solution having a temperature of 33 ° C., an iodine value of 0 (g / 100 g), and a solid content of 50% was obtained.

<(Meth) acrylic copolymer A15 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 18 parts of methyl methacrylate, 78 parts of n-butyl methacrylate, 4 parts of 2-hydroxylmethacrylate, and 100 parts of toluene, under a nitrogen atmosphere. The temperature was raised to 100 ° C. with stirring at 0.15 parts, 0.15 parts of azobisisobutyronitrile was added and the polymerization reaction was carried out for 2 hours, and then 0.07 parts of azobisisobutyronitrile was added, and another 2 hours. A polymerization reaction was carried out, 0.07 part of azobisisobutyronitrile was further added, and the polymerization reaction was further carried out for 2 hours.
Thereafter, 0.03 part of hydroquinone and 0.03 part of dibutyltin dilaurate were added, and 3.3 parts of 2-isocyanatoethyl methacrylate (the amount required for the modification of 2-hydroxylethyl methacrylate: 4 parts) was added to methyl ethyl ketone 3 The solution dissolved in 3 parts was added dropwise over 2 hours while stirring at 40 ° C. It was confirmed by IR that the isocyanate peak (2260 cm ⁻¹ ) had disappeared, the number average molecular weight was 37,000, the hydroxyl value was 0 (mgKOH / g), the Tg was 34 ° C., the iodine value was 0 (g / 100 g), A 50% (meth) acrylic copolymer A15 solution was obtained.

<(Meth) acrylic copolymer A16 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube, 18 parts of methyl methacrylate, 78 parts of n-butyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, 2 parts of glycidyl methacrylate, and 100 parts of toluene The temperature was raised to 100 ° C. while stirring in a nitrogen atmosphere, and 0.6 parts of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours. Next, 0.05 part of azobisisobutyronitrile was added. In addition, the polymerization reaction was further performed for 2 hours, and 0.05 part of azobisisobutyronitrile was further added to perform the polymerization reaction for another 2 hours.
Thereafter, 0.03 part of hydroquinone, 0.8 part of dimethylbenzylamine and 1 part of acrylic acid (the amount required for modification of 2-hydroxyethyl methacrylate: 2 parts) were added, and the mixture was heated and stirred at 100 ° C. for 15 hours. did. It was confirmed that the acid value was 2 or less, the number average molecular weight was 14,000, the hydroxyl value was 17.0 (mgKOH / g), the Tg was 31 ° C., the iodine value was 3.6 (g / 100 g), solid A 50% (meth) acrylic copolymer A16 solution was obtained.

<(Meth) acrylic copolymer A17 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube, n-butyl methacrylate 30 parts, 2-ethylhexyl methacrylate 66 parts, 2-hydroxyethyl methacrylate 2 parts, glycidyl methacrylate 2 parts, toluene 100 The temperature was raised to 100 ° C. with stirring in a nitrogen atmosphere, 0.15 part of azobisisobutyronitrile was added and a polymerization reaction was carried out for 2 hours, and then azobisisobutyronitrile was added in an amount of 0.00. 07 parts were added to conduct a polymerization reaction for another 2 hours, and 0.07 parts of azobisisobutyronitrile were further added to carry out the polymerization reaction for another 2 hours.
Thereafter, 0.03 part of hydroquinone, 0.8 part of dimethylbenzylamine and 1 part of acrylic acid (the amount required for modification of 2-hydroxyethyl methacrylate: 2 parts) were added, and the mixture was heated and stirred at 100 ° C. for 15 hours. did. It was confirmed that the acid value was 2 or less, the number average molecular weight was 35,000, the hydroxyl value was 18.3 (mgKOH / g), the Tg was 0 ° C., the iodine value was 3.6 (g / 100 g), solid A 50% (meth) acrylic copolymer A17 solution was obtained.

<(Meth) acrylic copolymer A18 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 96 parts of methyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, 2 parts of glycidyl methacrylate, and 100 parts of toluene, and stirred under a nitrogen atmosphere. The temperature was raised to 100 ° C., 0.15 part of azobisisobutyronitrile was added and the polymerization reaction was carried out for 2 hours, and then 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was carried out for another 2 hours. Then, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further carried out for 2 hours.
Thereafter, 0.03 part of hydroquinone, 0.8 part of dimethylbenzylamine and 1 part of acrylic acid (the amount required for modification of glycidyl methacrylate: 2 parts) were added, and the mixture was heated and stirred at 100 ° C. for 15 hours. It was confirmed that the acid value was 2 or less, the number average molecular weight was 30,000, the hydroxyl value was 16.7 (mgKOH / g), the Tg was 102 ° C., the iodine value was 3.6 (g / 100 g), solid A 50% (meth) acrylic copolymer A18 solution was obtained.

<(Meth) acrylic copolymer A19 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen inlet tube, 55 parts of methyl methacrylate, 20 parts of n-butyl methacrylate, 15 parts of 2-hydroxyethyl methacrylate, 10 parts of glycidyl methacrylate, and 100 parts of toluene The temperature was raised to 100 ° C. while stirring in a nitrogen atmosphere, 0.12 part of azobisisobutyronitrile was added and the polymerization reaction was carried out for 2 hours, and then 0.07 part of azobisisobutyronitrile was added. In addition, the polymerization reaction was further performed for 2 hours, and 0.07 part of azobisisobutyronitrile was further added to perform the polymerization reaction for another 2 hours.
Thereafter, 0.03 part of hydroquinone, 0.8 part of dimethylbenzylamine, and 5 parts of acrylic acid (the amount required for modification of glycidyl methacrylate: 10 parts) were added, and the mixture was heated and stirred at 100 ° C. for 15 hours. It was confirmed that the acid value was 2 or less, the number average molecular weight was 60,000, the hydroxyl value was 108.5 (mgKOH / g), Tg was 70 ° C., iodine value was 17.3 (g / 100 g), solid A 51% (meth) acrylic copolymer A19 solution was obtained.

<(Meth) acrylic copolymer A20 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen inlet tube was charged with 20 parts of methyl methacrylate, 48 parts of n-butyl methacrylate, 32 parts of 2-hydroxylmethacrylate, and 100 parts of toluene, under a nitrogen atmosphere. The temperature was raised to 100 ° C. with stirring at 0.15 parts, 0.15 parts of azobisisobutyronitrile was added and the polymerization reaction was carried out for 2 hours, and then 0.07 parts of azobisisobutyronitrile was added, and another 2 hours. A polymerization reaction was carried out, 0.07 part of azobisisobutyronitrile was further added, and the polymerization reaction was further carried out for 2 hours.
Thereafter, 0.03 part of hydroquinone and 0.03 part of dibutyltin dilaurate were added, and 25 parts of 2-isocyanatoethyl methacrylate (the amount required for modification of about 30 parts of 2-hydroxyethyl methacrylate: 32 parts) In 25 parts of methyl ethyl ketone was added dropwise over 2 hours with stirring at 40 ° C. It was confirmed by IR that the isocyanate peak (2260 cm ⁻¹ ) had disappeared, the number average molecular weight was 42,000, the hydroxyl value was 9.1 (mgKOH / g), the Tg was 45 ° C., and the iodine value was 57.6 (g / 100 g), a (meth) acrylic copolymer A20 solution having a solid content of 50% was obtained.

<(Meth) acrylic copolymer A21 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 18 parts of methyl methacrylate, 80 parts of n-butyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, and 100 parts of toluene under a nitrogen atmosphere. The temperature was raised to 100 ° C. with stirring. Subsequently, 0.15 part of azobisisobutyronitrile was added and a polymerization reaction was performed for 2 hours. Subsequently, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and further 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours. A (meth) acrylic copolymer A21 solution having an average molecular weight of 36,000, a hydroxyl value of 9.0 (mgKOH / g), a Tg of 31 ° C., an iodine value of 0 (g / 100 g), and a solid content of 50% Obtained.

<(Meth) acrylic copolymer A22 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 18 parts of methyl methacrylate, 80 parts of n-butyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, and 100 parts of toluene under a nitrogen atmosphere. The temperature was raised to 100 ° C. with stirring, and 0.40 part of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours. Subsequently, 0.05 parts of azobisisobutyronitrile was added to conduct a polymerization reaction for another 2 hours, and 0.05 parts of azobisisobutyronitrile was further added to carry out the polymerization reaction for another 2 hours. A (meth) acrylic copolymer A22 solution having an average molecular weight of 16,000, a hydroxyl value of 8.3 (mgKOH / g), a Tg of 33 ° C., an iodine value of 0 (g / 100 g), and a solid content of 50% Obtained.

<(Meth) acrylic copolymer A23 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 18 parts of methyl methacrylate, 80 parts of n-butyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, and 100 parts of toluene under a nitrogen atmosphere. The temperature was raised to 80 ° C. while stirring, and 0.075 part of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours. Subsequently, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and further 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours. A (meth) acrylic copolymer A23 solution having an average molecular weight of 76,000, a hydroxyl value of 8.0 (mgKOH / g), a Tg of 34 ° C., an iodine value of 0 (g / 100 g), and a solid content of 50% is obtained. Obtained.

<(Meth) acrylic copolymer A24 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen inlet tube was charged with 98 parts of n-butyl methacrylate, 2 parts of 2-hydroxylethyl methacrylate, and 100 parts of toluene, and stirred while stirring in a nitrogen atmosphere. The temperature was raised to 0 ° C., 0.15 part of azobisisobutyronitrile was added, and a polymerization reaction was carried out for 2 hours. Subsequently, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and further 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours. A (meth) acrylic copolymer A24 solution having an average molecular weight of 35,000, a hydroxyl value of 8.8 (mgKOH / g), a Tg of 19 ° C., an iodine value of 0 (g / 100 g), and a solid content of 50% Obtained.

<(Meth) acrylic copolymer A25 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 90 parts of methyl methacrylate, 8 parts of n-butyl methacrylate, 2 parts of 2-hydroxylethyl methacrylate, and 100 parts of toluene under a nitrogen atmosphere. The temperature was raised to 100 ° C. while stirring, and 0.15 part of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours. Subsequently, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and further 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours. (Meth) acrylic copolymer A25 solution having an average molecular weight of 40,000, a hydroxyl value of 8.0 (mgKOH / g), a Tg of 95 ° C., an iodine value of 0 (g / 100 g), and a solid content of 50% Obtained.

<(Meth) acrylic copolymer A26 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 35 parts of methyl methacrylate, 50 parts of n-butyl methacrylate, 15 parts of 2-hydroxylethyl methacrylate, and 100 parts of toluene under a nitrogen atmosphere. The temperature was raised to 100 ° C. while stirring, and 0.15 part of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours. Subsequently, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and further 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours. A (meth) acrylic copolymer A26 solution having an average molecular weight of 28,000, a hydroxyl value of 62.6 (mgKOH / g), a Tg of 51 ° C., an iodine value of 0 (g / 100 g), and a solid content of 50% Obtained.

<(Meth) acrylic copolymer A27 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 18 parts of methyl methacrylate, 78 parts of n-butyl methacrylate, 4 parts of 2-hydroxylmethacrylate, and 100 parts of ethyl acetate, and a nitrogen atmosphere Under stirring, the temperature was raised to 77 ° C., 0.05 part of azobisisobutyronitrile was added, and a polymerization reaction was carried out for 2 hours. Next, 22 parts of ethyl acetate and 0.05 part of azobisisobutyronitrile were added to conduct a polymerization reaction for 2 hours. Further, 22 parts of ethyl acetate and 0.05 part of azobisisobutyronitrile were added. In addition, a polymerization reaction was carried out for 2 hours. Thereafter, 36 parts of ethyl acetate and 0.05 parts of azobisisobutyronitrile were added to conduct a polymerization reaction for 2 hours, and 0.05 parts of azobisisobutyronitrile was further added to conduct a polymerization reaction for 2 hours. (Meth) acrylic copolymer solution A27 having a number average molecular weight of 244,000, a hydroxyl value of 16.0 (mgKOH / g), a Tg of 35 ° C., an iodine value of 0 (g / 100 g), and a solid content of 35% Got.

<(Meth) acrylic copolymer A28 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 57 parts of methyl methacrylate, 20 parts of n-butyl methacrylate, 23 parts of 2-hydroxylmethacrylate, and 100 parts of toluene, under a nitrogen atmosphere. The temperature was raised to 100 ° C. with stirring at 0.13 parts, 0.13 parts of azobisisobutyronitrile was added and the polymerization reaction was carried out for 2 hours, and then 0.07 parts of azobisisobutyronitrile was added, and another 2 hours. A polymerization reaction was performed. Further, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further carried out for 2 hours. The number average molecular weight was 42,000, the hydroxyl value was 97.9 (mgKOH / g), Tg was 73 ° C., iodine value. Was 0 (g / 100 g), and an acrylic resin solution A28 having a solid content of 50% was obtained.

<(Meth) acrylic copolymer A29 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen inlet tube was charged with 18 parts of methyl methacrylate, 82 parts of n-butyl methacrylate, and 100 parts of toluene, and the temperature was raised to 100 ° C. while stirring in a nitrogen atmosphere. The mixture was warmed, 0.15 part of azobisisobutyronitrile was added, and the polymerization reaction was carried out for 2 hours. Subsequently, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and further 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours. A (meth) acrylic copolymer A29 solution having an average molecular weight of 42,000, a hydroxyl value of 0 (mgKOH / g), a Tg of 36 ° C., an iodine value of 0 (g / 100 g), and a solid content of 50% was obtained. .

<(Meth) acrylic copolymer A30 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 18 parts of methyl methacrylate, 80 parts of n-butyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, and 100 parts of toluene under a nitrogen atmosphere. The temperature was raised to 100 ° C. with stirring, and 0.6 parts of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours. Subsequently, 0.05 parts of azobisisobutyronitrile was added to conduct a polymerization reaction for another 2 hours, and 0.05 parts of azobisisobutyronitrile was further added to carry out the polymerization reaction for another 2 hours. A (meth) acrylic copolymer A30 solution having an average molecular weight of 12,000, a hydroxyl value of 8.6 (mgKOH / g), a Tg of 33 ° C., an iodine value of 0 (g / 100 g), and a solid content of 50% is obtained. Obtained.

<(Meth) acrylic copolymer A31 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 32 parts of n-butyl methacrylate, 66 parts of 2-ethylhexyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, and 100 parts of toluene, and nitrogen. While stirring in an atmosphere, the temperature was raised to 100 ° C., 0.15 part of azobisisobutyronitrile was added, and a polymerization reaction was performed for 2 hours. Subsequently, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and further 0.307 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours. A (meth) acrylic copolymer A31 solution having an average molecular weight of 36,000, a hydroxyl value of 9.2 (mgKOH / g), a Tg of 2 ° C., an iodine value of 0 (g / 100 g), and a solid content of 50% Obtained.

<(Meth) acrylic copolymer A32 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen inlet tube is charged with 98 parts of methyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, and 100 parts of toluene, and is stirred up to 100 ° C. in a nitrogen atmosphere. The temperature was raised, 0.15 part of azobisisobutyronitrile was added, and a polymerization reaction was carried out for 2 hours. Subsequently, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and further 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours. A (meth) acrylic copolymer A32 solution having an average molecular weight of 38,000, a hydroxyl value of 8.1 (mgKOH / g), a Tg of 104 ° C., an iodine value of 0 (g / 100 g), and a solid content of 50% is obtained. Obtained.

<(Meth) acrylic copolymer A33 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 20 parts of methyl methacrylate, 55 parts of n-butyl methacrylate, 25 parts of 2-hydroxyethyl methacrylate, and 100 parts of toluene, and under a nitrogen atmosphere The temperature was raised to 100 ° C. while stirring, and 0.15 part of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours. Subsequently, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and further 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours. A (meth) acrylic copolymer A33 solution having an average molecular weight of 37,000, a hydroxyl value of 109 (mgKOH / g), a Tg of 44 ° C., an iodine value of 0 (g / 100 g), and a solid content of 50% was obtained. .

<Polyisocyanate compound solution B>
The isocyanurate form of hexamethylene diisocyanate blocked with 3,5-dimethylpyrazole was diluted to 75% with ethyl acetate to obtain a polyisocyanate compound solution (B).

<Compounds C1 to C6 having (meth) acryloyl group>
As the compounds C1 to C6 having a (meth) acryloyl group, the compounds described in Tables 4 and 5 were used as they were.

<Allyl group-containing compounds H1 to H4>
As the allyl group-containing compounds H1 to H4, the compounds described in Tables 4 and 5 were used as they were.

<Adjustment of easy adhesive solutions 1-25>
The (meth) acrylic copolymer (A) solution and the polyisocyanate compound (B) solution were mixed in the composition shown in Table 3, and the solid content of the (meth) acrylic copolymer (A) solution was 100 parts by weight. In contrast, 0.01 parts by weight of dioctyltin laurate was blended as a catalyst to obtain easy-adhesive solutions 1-25.

<Adjustment of easy adhesive solutions 26-56>
The compositions shown in Tables 4 and 5 are (meth) acrylic copolymer (A) solution, polyisocyanate compound (B) solution, compound (C) having (meth) acryloyl group, and allyl group-containing compound (H). In addition, 0.01 parts by weight of dioctyltin laurate as a catalyst is blended with respect to 100 parts by weight of the solid content of the (meth) acrylic copolymer (A) solution. 56 was obtained.

<Measurement of iodine value of easy adhesive solution>
The easy adhesive solutions 1 to 56 were heated at 120 ° C. for 60 minutes to dryness, and the iodine value was measured by the method described above.

<Creation of polyester film 1>
A polyester resin having an intrinsic viscosity of 0.67 (dl / g) and a cyclic trimer content of 0.5% by weight with a T-die extruder at a set temperature of 250 ° C. and having a thickness of 125 μm Film 1 was created.

<Production of protective sheet for solar cell>
One side of the polyester film 1 is corona-treated, the easy-adhesive solution 1 is applied to the treated surface with a gravure coater, the solvent is dried, and an easy-adhesive layer with a coating amount of 1 g / square meter is provided. 1 was produced.

  Similarly to the solar cell protective sheet 1, solar cell protective sheets 2 to 56 were prepared using the easy-adhesive solutions 2 to 56.

  A protective sheet 57 for solar cells was obtained by corona-treating one surface of the polyester film 1.

<Preparation of adhesive strength evaluation sample>
White plate glass, vinyl acetate-ethylene copolymer film (manufactured by Sanvic Co., Ltd., standard cure type, hereinafter referred to as EVA film), solar cell protective sheet 1, solar cell protective sheet 1 easy adhesive layer as EVA film It was piled up in order to touch. Then, this laminate was put into a vacuum laminator, evacuated to about 1 Torr, heated at 150 ° C. for 30 minutes at a press pressure of 0.1 MPa, and further heated at 150 ° C. for 30 minutes to evaluate the adhesive strength of 10 cm × 10 cm square. Sample 1 was prepared.

  In the same manner as in Adhesive Strength Evaluation Sample 1, Adhesive Strength Evaluation Samples 2 through 56 were produced using the solar cell protective sheets 2 through 56.

  The white sheet glass, the EVA film, and the solar cell protective sheet 57 are stacked in order so that the corona-treated surface of the solar cell protective sheet 57 is in contact with the EVA film. 57 was produced.

[Example 1]
Using the adhesive strength evaluation sample 1, the adhesion of the easy-adhesive layer to the EVA film and the wet heat resistance test (1000 hours and 2000 hours) were evaluated by the method described later.

<Adhesion measurement>
Cut one surface of the solar cell protective sheet of the adhesive evaluation sample 1 into a width of 15 mm with a cutter, and measure the adhesive force between the easy-adhesive layer formed on the solar cell protective sheet 1 and the EVA film as a sealing material. did. For the measurement, a tensile tester was used, and a 180 degree peel test was performed at a load speed of 100 mm / min. The obtained measurement values were evaluated as follows.
◎: 50 N / 15 mm or more ○: 30 N / 15 mm or more to less than 50 N / 15 mm Δ: 10 N / 15 mm or more to less than 30 N / 15 mm ×: less than 10 N / 15 mm

<Adhesiveness after wet heat resistance test>
Adhesive strength evaluation sample 1 was allowed to stand for 1000 hours and 2000 hours under the environmental conditions of a temperature of 85 ° C. and a relative humidity of 85% RH, and then the adhesiveness was evaluated after the wet heat resistance test in the same manner as the adhesiveness measurement. It was.

[Examples 2-35], [Comparative Examples 1-21]
In the same manner as in Example 1, adhesiveness evaluation samples 2 to 56 were used to evaluate the adhesion of the easy-adhesive layer to the EVA film and the adhesion after the wet heat resistance test.

[Comparative Example 22]
Using the sample 57 for adhesive strength evaluation produced without using the easy-adhesive solution, the adhesion between the polyester film surface and the EVA film and the adhesion after the wet heat resistance test were evaluated.
The results are shown in Table 5.

  As shown in Tables 3 and 4, in Examples 1 to 16 and 17 to 35, the solar cell protective sheet using the easy-adhesive agent of the present invention has sufficient adhesion and moisture resistance to the EVA film. Adhesive after thermal test.

On the other hand, as shown in Tables 3 and 5, Comparative Example 1 and Comparative Example 15 are inferior in adhesiveness because the iodine value is 0.
In Comparative Example 2 and Comparative Example 10, since the OH value is smaller than 2, the crosslinking is not sufficient and the adhesiveness after the wet heat resistance test is inferior.
In Comparative Example 3 and Comparative Example 11, the number average molecular weight of the acrylic copolymer is too low and the adhesiveness after the wet heat resistance test is poor.
Comparative Example 4 and Comparative Example 12 are inferior in adhesiveness because the Tg of the (meth) acrylic copolymer (A) is too low and the cohesive force is small, and Comparative Examples 5 and 13 are (meth) acrylic. Since the Tg of the copolymer (A) is too high and the easy-adhesive layer (D ′) becomes hard, the adhesiveness is poor.

In Comparative Example 6 and Comparative Example 14, the OH value of the acrylic copolymer is larger than 100, and in Comparative Example 7, since the iodine value is too large, the cross-linking becomes excessive and the adhesiveness is poor.
In Comparative Example 8 and Comparative Example 20, the NCO / OH ratio of the acrylic copolymer and the curing agent is 0, so that the adhesiveness after the wet heat resistance test is inferior. In Comparative Example 9 and Comparative Example 21, the NCO / OH ratio is 10 In this case, the cross-linking becomes excessive and the adhesiveness and the adhesiveness after the wet heat resistance test are poor.

  In Comparative Examples 16 to 19, the allyl group-containing compound (H) is added instead of the compound (B) having a (meth) acryloyl group, but the allyl group is less reactive than the (meth) acryloyl group. Therefore, a sufficient effect of improving the adhesive strength cannot be obtained.

[Example 36]
<Production of solar cell module>
White glass ... Solar cell surface protective material (I)
EVA film: Light-receiving surface side sealing material (II)
Polycrystalline silicon solar cell element ... Solar cell (III)
EVA film: Non-light-receiving surface side sealing material (IV)
As the above (I)-(IV) and the solar cell back surface protective material (V), the solar cell protective sheet 1 is used, and the solar cell protective sheet 1 has a non-light-receiving surface side sealing material (IV). In order to be in contact with each other, placed in a vacuum laminator, evacuated to about 1 Torr, heated at 150 ° C. for 30 minutes under a pressure of atmospheric pressure as a press pressure, and further heated at 150 ° C. for 30 minutes. And the solar cell module 1 for photoelectric conversion efficiency evaluation of 10 cm x 10 cm square was produced.

<Measurement of photoelectric conversion efficiency>
The solar cell output of the obtained solar cell module 1 was measured, and the photoelectric conversion efficiency was measured using a solar simulator (SS-100XIL, manufactured by Eihiro Seiki Co., Ltd.) according to JIS C8912.
Furthermore, the photoelectric conversion efficiency after the heat and humidity resistance test after standing for 500 hours, 1000 hours, 1500 hours, and 2000 hours under environmental conditions of a temperature of 85 ° C. and a relative humidity of 85% RH was measured in the same manner. The ratio of the decrease in photoelectric conversion efficiency after the wet heat resistance test with respect to the initial photoelectric conversion efficiency was calculated and evaluated as follows.
○: Output decrease is less than 10% Δ: Output decrease is from 10% to less than 15% ×: Output decrease is 20% or more

[Examples 37 to 45], [Comparative Examples 23 to 28]
In the same manner as in Example 36, solar cell modules 2-16 were produced using the solar cell protective sheets 2-5, 17-19, 26-30, 45-47, and the photoelectric conversion efficiency (initial, wet heat resistance test) After) was measured.

[Comparative Example 29]
In the same manner as in Example 36, except that the solar cell protective sheet 57 was used instead of the solar cell protective sheet 1 and the corona-treated surface was laminated so as to be in contact with the sealing material (IV) on the non-light-receiving surface side. Photoelectric conversion efficiency (initial, after wet heat resistance test) was measured. The results are shown in Table 6.

  As shown in Table 6, Examples 37 to 46 do not show a decrease in output, but Comparative Examples 23 to 28 have insufficient adhesion between the EVA film and the solar cell protective sheet. The solar cell element is deteriorated, and the photoelectric conversion efficiency is lowered.

[Example 46]
<Production of solar cell module>
EVA film: Light-receiving surface side sealing material (II)
Polycrystalline silicon solar cell element ... Solar cell (III)
EVA film: Non-light-receiving surface side sealing material (IV)
As the above (II)-(IV), the solar cell surface protective member (I), and the solar cell back surface protective material (V), the solar cell protective sheet 1 is received by the solar cell protective sheet 1 and the easy-adhesive layer. After stacking in order so as to contact the sealing material (II) on the surface side and the sealing material (IV) on the non-light-receiving surface side, it is put into a vacuum laminator, evacuated to about 1 Torr, and the pressure of atmospheric pressure as the press pressure After heating at 150 ° C. for 30 minutes, the solar cell module 18 for photoelectric conversion efficiency evaluation of 10 cm × 10 cm square was prepared by heating at 150 ° C. for 30 minutes.

<Measurement of photoelectric conversion efficiency>
The solar cell output of the obtained solar cell module 18 was measured, and the photoelectric conversion efficiency was measured using a solar simulator (SS-100XIL, manufactured by Eihiro Seiki Co., Ltd.) according to JIS C8912.
Furthermore, the photoelectric conversion efficiency after the heat and humidity resistance test after standing for 500 hours, 1000 hours, 1500 hours, and 2000 hours under environmental conditions of a temperature of 85 ° C. and a relative humidity of 85% RH was measured in the same manner. The ratio of the decrease in photoelectric conversion efficiency after the wet heat resistance test with respect to the initial photoelectric conversion efficiency was calculated and evaluated as follows.
○: Output decrease is less than 10% Δ: Output decrease is from 10% to less than 15% ×: Output decrease is 20% or more

[Examples 47 to 55], [Comparative Examples 30 to 35]
In the same manner as in Example 46, solar cell modules 18-33 were produced using solar cell protective sheets 2-5, 17-19, 26-30, 45-47, and photoelectric conversion efficiency (initial, wet heat resistance test). After) was measured.

[Comparative Example 36]
The solar cell protective sheet 57 is used in place of the solar cell protective sheet 1, and the solar cell protective sheet 57 has a corona-treated surface on the light receiving surface side sealing material (II) and a non-light receiving surface side sealing material (IV ) Was measured in the same manner as in Example 46 except that the layers were laminated so as to be in contact with each other). The results are shown in Table 7.

  As shown in Table 7, Examples 47 to 56 do not show a decrease in output, but Comparative Examples 30 to 36 have insufficient adhesion between the EVA film and the solar cell protective sheet. The solar cell element is deteriorated, and the photoelectric conversion efficiency is lowered.

I Solar cell surface protective material positioned on the light receiving surface side of the solar cell II Sealing material positioned on the light receiving surface side of the solar cell III Solar cell IV Sealing material positioned on the non-light receiving surface side of the solar cell V Solar cell back surface protective material located on non-light-receiving surface side of solar cell

Claims (9)

A solar cell protective sheet comprising an easy-adhesive layer (1 ′) as the outermost surface and a plastic film (2) having one main surface supporting the easy-adhesive layer (1 ′),
The easy-adhesive layer (1 ′) has a glass transition temperature of 10 to 100 ° C., a number average molecular weight of 15,000 to 250,000, and a hydroxyl value of 2 to 100 (mgKOH / g). The polyisocyanate compound (B) is contained in the range of 0.1 to 5 isocyanate groups with respect to one hydroxyl group in the copolymer (A) and the (meth) acrylic copolymer (A). , An easy-adhesive layer (1 ′) containing a carbon-carbon double bond derived from a (meth) acryloyl group in an amount defined by an iodine value of 0.01 to 50 (g / 100 g),
The plastic film (2) is a polyester film made of a polyester resin having an intrinsic viscosity of 0.6 (dl / g) or more and a cyclic trimer content of 1% by weight or less. Protective sheet for solar cell (Z ′). The easy-adhesive layer (1 ′) as the outermost surface,
Contains an acrylic copolymer (A1) having a carbon-carbon double bond derived from a (meth) acryloyl group, or
The protective sheet for solar cells according to claim 1, comprising an acrylic copolymer (A2) having no (meth) acryloyl group and a compound (C) having a (meth) acryloyl group. '). The (meth) acrylic copolymer (A1) is a copolymer selected from the group consisting of the following (meth) acrylic copolymers (A1-1) to (A1-4). The solar cell protective sheet (Z ′) according to claim 2.
(Meth) acrylic copolymer (A1-1): (meth) acrylic monomer (a1) having a glycidyl group, (meth) acrylic monomer (a2) having a hydroxyl group, glycidyl group, hydroxyl group and carboxyl group The (meth) acrylic monomer (a3) having a carboxyl group is reacted with the glycidyl group in the side chain in the copolymer having the (meth) acrylic monomer (a4) having no structural unit ( (Meth) acrylic copolymers,
(Meth) acrylic copolymer (A1-2): (meth) acrylic monomer (a3) having a carboxyl group, (meth) acrylic monomer (a2) having a hydroxyl group, glycidyl group and hydroxyl group are both carboxyl groups (Meth) acrylic monomer obtained by reacting a (meth) acrylic monomer (a1) having a glycidyl group with a carboxyl group in a copolymer having a (meth) acrylic monomer (a4) having no structural unit. Copolymer,
(Meth) acrylic copolymer (A1-3): Copolymer having a (meth) acrylic monomer (a2) having a hydroxyl group and a (meth) acrylic monomer (a6) having no hydroxyl group as structural units A (meth) acrylic copolymer obtained by reacting an isocyanate group-containing (meth) acrylic monomer (a5) with a part of the hydroxyl groups in the coalescence;
(Meth) acrylic copolymer (A1-4): a copolymer comprising maleic anhydride, an acrylic monomer (a2) having a hydroxyl group, and an acrylic monomer (a6) having no hydroxyl group as constituent units. A (meth) acrylic copolymer obtained by reacting an acid anhydride group therein with an acrylic monomer (a2) having a hydroxyl group.   The compound (C) having a (meth) acryloyl group is contained in an amount of 0.1 to 20 parts by weight with respect to 100 parts by weight of the (meth) acrylic copolymer (A2). The solar cell protective sheet (Z ′).   The solar cell protective sheet (Z ') according to claim 4, wherein the compound (C) having the (meth) acryloyl group has two or more (meth) acryloyl groups in a molecule.   The solar cell protective sheet (Z ') according to any one of claims 1 to 5, wherein the polyisocyanate compound (B) is a blocked polyisocyanate (B1). Solar cell surface protecting material (I) located on the light receiving surface side of the solar cell, sealing material (II) located on the light receiving surface side of the solar cell, solar cell (III), located on the non-light receiving surface side of the solar cell A solar cell module comprising a sealing material (IV) and a solar cell back surface protective material (V) located on the non-light-receiving surface side of the solar cell,
At least any one of the solar cell surface protective material (I) or the solar cell back surface protective material (V) attaches the solar cell protective sheet (Z ') according to any one of claims 1 to 6 to the easy adhesion. By arranging the agent layer (1 ′) in contact with the sealing material on the light receiving surface side or the sealing material on the non-light receiving surface side, and curing the easy-adhesive layer for the solar cell protective sheet. The obtained solar cell module.   The solar cell module according to claim 7, wherein the sealing material (II) on the light receiving surface side or the sealing material (IV) on the non-light receiving surface side contains an organic peroxide.   The sealing material (II) on the light-receiving surface side or the sealing material (IV) on the non-light-receiving surface side contains ethylene-vinyl acetate copolymer (EVA) as a main component. 9. The solar cell module according to 8.

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