JP2014074149A - Easily adhesive sheet, protective sheet for solar cell, insulation sheet, back sheet member for sola cell, back sheet for solar cell and solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easily adhesive sheet having good adhesion force to a seal material even after being left under a moist and hot environment.SOLUTION: An easily adhesive sheet contains an olefin-acryl composite polymer layer containing a substrate film, an olefin resin arranged on at least a single side of the substrate film and having an elasticity modulus of 320 MPa or less, an acrylic resin, a coloring pigment and a crosslinking agent and has a ratio of the acrylic resin to the sum of the acrylic resin and the olefin resin in a range of 25 to 55 mass%.

Description

  The present invention relates to an easily adhesive sheet, a solar cell protective sheet, an insulating sheet, a solar cell backsheet member, a solar cell backsheet, and a solar cell module.

  A solar cell module using crystalline silicon, amorphous silicon, or the like as a solar cell element is generally a transparent front substrate on which sunlight is incident, and a solar cell element as a photovoltaic element is sealed with a sealing material. The battery side substrate and the back surface protection sheet layer (solar cell backsheet) are laminated in this order, and are manufactured using a lamination method or the like in which vacuum suction is applied to perform thermocompression bonding. Since solar cells are placed in an environment where sunlight shines on the roof, etc., and is exposed to rain, the layers that make up the solar cell module have various functionalities that are representative of durability under humid heat environments. Is required.

Conventionally, glass has often been used as a transparent front substrate or solar cell backsheet, but various functionalities can be added by laminating functional layers, reducing the weight of the solar cell module and reducing the cost. From the viewpoint of reduction, etc., it has recently been required to use a solar cell protective sheet using a base material mainly composed of a resin film as a front substrate or a solar cell backsheet.
Such a protective sheet for a solar cell is often a laminate of various functional layers as described above. Typical functional layers include an adhesive layer for adhering to the sealing material and a function of reflecting sunlight transmitted through the transparent front substrate and the battery-side substrate to increase the expression efficiency of the solar cell element. The white layer for raising, the weatherproof layer etc. which are preferably installed in the outermost layer of the protection sheet for solar cells can be mentioned.

  The functionality required for the solar cell protective sheet is various as described above, and among them, durability under a wet heat environment that is directly related to the life of the solar cell module is particularly required. From the viewpoint of durability of the solar cell module in a moist heat environment, it is most important that the sealing material and the solar cell protective sheet are peeled off and moisture does not enter the battery side substrate. That is, there is a demand for a solar cell protective sheet that has good adhesion to a sealing material used in a solar cell module in a wet heat environment.

  However, the outermost layer of the solar cell backsheet that is in contact with the encapsulant used in the solar cell module is often not considered even in a normal environment, as well as in a wet heat environment. It was. For example, Patent Document 1 describes that a solar cell back sheet is simply laminated on a filler (encapsulant) made of an ethylene-vinyl acetate copolymer (hereinafter also referred to as EVA). It is not described whether it was adhered to. Moreover, various aspects of the outermost layer of the solar cell backsheet on the encapsulant side are described, and none of the adhesion to the encapsulant is mentioned. Moreover, in patent document 2, although the sealing material used for a solar cell backsheet and a solar cell module is laminated | stacked through the extrusion resin layer by a resin composition, it is thermocompression-bonded. There is no description about composition and physical properties.

  On the other hand, the example which provides an adhesive bond layer between the sealing material used for a solar cell module and the outermost layer of the solar cell backsheet by the side of a sealing material is described. For example, Patent Document 3 discloses a heat-resistant material including an inorganic oxide vapor-deposited film on one side of a base film and a whitening agent and an ultraviolet absorber on both sides of the base film provided with the inorganic oxide vapor-deposited film. A solar cell backsheet laminated with a conductive polypropylene resin film is described, and in the examples of the same document, the outermost layer of the solar cell backsheet is laminated with a sealing material made of EVA by an acrylic adhesive layer. Embodiments have been disclosed.

On the other hand, in recent years, the material of the outermost layer of the solar cell backsheet on the sealing material side has been studied, and the outermost layer of the solar cell backsheet on the sealing material side and the sealing material used in the solar cell module are examined. There are also a few known examples of direct bonding (see Patent Document 4). In patent document 4, in the solar cell backsheet composed of at least two layers including a weather-resistant substrate film, titanium oxide is applied to the innermost surface to be bonded to the filler constituting the solar cell module of the solar cell backsheet. An embodiment having an adhesive coating layer colored with a white pigment as a main component is described. In Patent Document 4, acrylic, epoxy, phenolic, polyester, urethane, styrene resin, silicon resin, or a modified product thereof is preferable as the resin for the adhesive coating layer having adhesion to EVA. It is described that it is preferable to include a polyacrylic acid resin. Moreover, in the Example of the same literature, only the aspect using the adhesive application layer containing the acrylic resin and acrylic acid resin which introduce | transduced the polyester frame | skeleton is disclosed. Furthermore, in Patent Document 4, as a white pigment, 0.1 to 30% by mass of rutile titanium dioxide having an average particle diameter of 0.1 to 0.5 μm is added to the total mass of the adhesive coating layer. Is described.
Patent Document 5 discloses a sheet in which a coating liquid containing silicon, tin, zirconium, and aluminum as fine particles is coated on a PET film with an olefin resin, an oxazoline compound, and fine particles.
Patent Document 6 discloses a sheet in which a coating liquid containing an acid-modified polyolefin resin and an oxazoline crosslinking agent is coated on a PET film. Further, Patent Document 6 does not describe an aspect in which titanium oxide particles are added to the coating solution.

Japanese Patent No. 2006-073793 JP 2006-210557 A JP 2007-306006 A JP 2010-109240 A JP 2011-29397 A JP 2010-251679 A

However, when the present inventors manufactured a solar cell module by the method described in Patent Documents 3 and 4 and aged in a humid heat environment, the solar cell module sealing material and the solar cell protective sheet still remained. There was a level of dissatisfaction with the adhesion in the wet heat environment.
Further, it is described that the sheet described in Patent Document 6 is excellent in strength retention in a high-temperature and high-humidity environment. However, since it has become possible to improve production efficiency in recent years, it has not reached the required level of adhesion when using high-speed crosslinked EVA, which is increasing in use. It was found that there was dissatisfaction with the adhesion after the treatment.
As described above, the problem to be solved by the present invention is to provide a solar cell protective sheet having a good adhesion with a sealing material even when aged in a humid heat environment.

As a result of intensive studies aimed at solving the above-mentioned problems, the present inventors have used a composite binder having a specific elastic modulus range and containing a polyolefin resin having a specific skeleton and an acrylic resin, and a coloring pigment. And a layer added with a cross-linking agent was found to improve the EVA adhesion when held for 48 hours (wet heat aging) at 105 ° C. and 100% relative humidity.
In particular, a composite binder containing a specific polyolefin resin and an acrylic resin and a color pigment are added to the layer without adding a cross-linking agent, or a composite binder containing a specific polyolefin resin and an acrylic resin and a cross-linking agent are added. The layer added with a specific binder resin, a composite binder containing an acrylic resin, a color pigment, and a cross-linking agent is 30 ° C. and 100% relative humidity than the layer not added with the color pigment. It has been found that EVA adhesion can be improved when held for a period of time (wet heat aging). Furthermore, a specific polyolefin resin is used rather than a layer (a mode not including an acrylic resin) using a binder having a specific elastic modulus and containing only a polyolefin resin having a specific skeleton and having a color pigment and a crosslinking agent added thereto. And a layer to which a colored pigment and a crosslinking agent are added using a composite binder containing an acrylic resin, and when the layer is held for 30 hours (wet heat aging) at 120 ° C. and 100% relative humidity. It was found that internal fracture of the material film can be suppressed, and as a result, the EVA adhesion can be greatly improved.
That is, the configuration of the present invention, which is a specific means for solving the above problems, is as follows.

[1] Olefin-acrylic containing a base film, an olefin resin that is disposed on at least one side of the base film, and has an elastic modulus of 320 MPa or less, an acrylic resin, a color pigment, and a crosslinking agent It has a composite polymer layer, The ratio of the said acrylic resin with respect to the sum total of the said acrylic resin and the said olefin resin is the range of 25-55 mass%, The easily adhesive sheet characterized by the above-mentioned.
[2] In the easy-adhesion sheet according to [1], it is preferable that the main chain of the olefin resin is ethylene and includes a (meth) acrylic acid ester unit.
[3] In the easy-adhesion sheet according to [1] or [2], it is preferable that the acrylic resin includes an alkyl (meth) acrylate unit.
[4] In the easy-adhesion sheet according to [1] or [2], it is preferable that the acrylic resin includes a 2-ethylhexyl (meth) acrylate unit.
[5] In the easy-adhesion sheet according to any one of [1] to [4], the base film is preferably a polyester film.
[6] The easy-adhesion sheet according to any one of [1] to [5] includes an olefin resin having an elastic modulus of 320 MPa or less between the base film and the olefin-acrylic composite polymer layer. It is preferable to have a layer.
[7] In the easy-adhesion sheet according to [6], the thickness of the undercoat layer is preferably 2 μm or less.
[8] In the easy-adhesion sheet according to any one of [1] to [7], the crosslinking agent is preferably a compound having an oxazoline group.
[9] In the easy-adhesion sheet according to [8], the compound having an oxazoline group is preferably water-soluble.
[10] In the easy-adhesive sheet according to any one of [1] to [9], in the olefin-acrylic composite polymer layer, a ratio of the crosslinking agent to a total of the olefin resin and the acrylic resin is 10 to 10. It is preferable that it is 75 mass%.
[11] The easy-adhesion sheet according to any one of [1] to [10] preferably further contains a catalyst for the crosslinking agent.
[12] In the easy-adhesion sheet according to [11], the catalyst for the crosslinking agent is preferably an onium compound.
[13] In the easily adhesive sheet according to [12], the onium compound is preferably at least one selected from the group consisting of an ammonium salt, a sulfonium salt, an iodonium salt, and a phosphonium salt.
[14] In the easy-adhesion sheet according to [12], the onium compound is preferably dibasic ammonium phosphate.
[15] In the easy-adhesion sheet according to any one of [11] to [14], the ratio of the catalyst of the crosslinking agent to the crosslinking agent is preferably 0.1% by mass or more and 15% by mass or less. .
[16] [1] easy adhesive sheet according to any one of to [15], wherein the olefin - the content of the coloring pigment to acrylic composite polymer layer is 2g / m ² ~20g / m ² Is preferred.
[17] In the easy-adhesion sheet according to any one of [1] to [16], the volume fraction of the color pigment with respect to the olefin-acrylic composite polymer layer is preferably 15 to 40%.
[18] In the easy-adhesion sheet according to any one of [1] to [17], the color pigment is preferably titanium oxide or carbon black.
[19] In the easy-adhesion sheet according to any one of [1] to [18], the color pigment is preferably titanium oxide.
[20] In the easy-adhesion sheet according to any one of [1] to [19], the thickness of the olefin-acrylic composite polymer layer is preferably 30 μm or less.
[21] The easy-adhesion sheet according to any one of [1] to [20] is preferably formed by coating the olefin-acrylic composite polymer layer.
[22] The easy-adhesion sheet according to any one of [1] to [21] is provided on a surface of the base film opposite to a surface on which the olefin-acrylic composite polymer layer is disposed. It is preferable to have a weather-resistant layer containing at least one of fluorine-based resin and silicone-acrylic composite resin.
[23] The surface on the side opposite to the surface on which the olefin-acrylic composite polymer layer of the base film is disposed, including the easy-adhesive sheet according to any one of [1] to [22]. The olefin-acrylic composite polymer layer is also disposed on the insulating sheet.
[24] The easily adhesive sheet according to any one of [1] to [22] or the insulating sheet according to [23], wherein the olefin-acrylic composite polymer layer of the base film is disposed. The solar cell protective sheet, wherein the side surface has a light reflectance at a wavelength of 550 nm of 70% or more.
[25] The sun comprising the easy-adhesive sheet according to any one of [1] to [22], the insulating sheet according to [23], or the solar cell protective sheet according to [24]. A battery backsheet member or a solar battery backsheet.
[26] The back sheet member for solar cells or the back sheet for solar cells according to [25], and at least the olefin-acrylic composite polymer layer side surface of the back sheet member for solar cells or the back sheet for solar cells. And a polymer layer comprising an ethylene-vinyl acetate copolymer which is adhered to the laminate for a solar cell.
[27] A transparent front substrate on the side on which sunlight is incident, a solar cell element, a sealing material that seals the solar cell element, and a side of the sealing material that is opposite to the front substrate. The solar cell backsheet that adheres to the sealing material, and the solar cell backsheet includes the solar cell backsheet member or solar cell backsheet described in [25]. A solar cell module.
[28] A transparent front substrate on the side on which sunlight is incident, a solar cell element, a sealing material that seals the solar cell element, and a side of the sealing material that is opposite to the front substrate. A solar cell backsheet that adheres to the sealing material, and includes the solar cell laminate according to [26] as the solar cell backsheet and the sealing material. module.

  ADVANTAGE OF THE INVENTION According to this invention, the protective sheet for solar cells with a favorable adhesive force with a sealing material is provided even if it carries out time-lapse | temporality in a humid heat environment.

It is sectional drawing which shows roughly an example of a structure of the solar cell module of this invention.

Hereinafter, the easy-adhesion sheet of the present invention and materials used therefor will be described in detail.
The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Easily adhesive sheet]
Easy-adhesive sheet of the present invention (Since the protective sheet for a solar cell of the present invention described later includes the easy-adhesive sheet of the present invention, hereinafter, when the easy-adhesive sheet of the present invention is used for solar cells in the present specification, A protective sheet for a solar cell) is disposed on at least one side of the base film, the base film, an olefin resin having an elastic modulus of 320 MPa or less, an acrylic resin, a color pigment, It has an olefin-acrylic composite polymer layer containing a crosslinking agent, and the ratio of the acrylic resin to the total of the acrylic resin and the olefin resin is in the range of 25 to 55 mass%.
With such a configuration, the solar cell protective sheet of the present invention has good adhesion to the sealing material after wet heat aging. Further, due to the above characteristics of the protective sheet for solar cells of the present invention, the solar cell module using the protective sheet for solar cells of the present invention has an adhesive force with the good sealing material of the protective sheet for solar cells of the present invention. In addition, it is possible to stably maintain the power generation performance for a long period of time without causing peeling or the like over time in a humid heat environment.
Hereinafter, the protective sheet for solar cells of the present invention will be described.

<Configuration of easy-adhesion sheet>
FIG. 1 shows an easy-adhesive sheet of the present invention, a back sheet member for solar cells using the easy-adhesive sheet of the present invention as a protective sheet for solar cells, a back sheet for solar cells, a laminate for solar cells, and a book An example of the structure of the solar cell module using the protection sheet for solar cells of invention is shown. In the solar cell protective sheet 31, the olefin-acrylic composite polymer layer 18 is provided on one surface of the base film 16. When the solar cell protective sheet of the present invention is used as an embodiment without such a weather-resistant layer, it is also referred to as a solar cell backsheet member of the present invention. Furthermore, another layer 17 may be provided between the base film 16 and the olefin-acrylic composite polymer layer 18. An overcoat layer (not shown) may be further provided on the olefin-acrylic composite polymer layer 18.
It is preferable that a weather resistant layer is provided on the other surface of the base film 16. The base film 16 is preferably provided with two weathering layers, a weathering layer first layer 14 and a weathering layer second layer 12. Thus, if it has the weather resistance layer 16, the protective sheet for solar cells of this invention can be used as the solar cell backsheet 32 as it is.
In the solar cell module 10 of the present invention, it is preferable that a transparent front substrate 24 is disposed on the side of the sealing material 22 opposite to the solar cell protective sheet of the present invention.

<Each component of easy adhesive sheet>
Hereinafter, a preferable aspect is demonstrated about each structural member which comprises the easily bonding sheet | seat of this invention.

(Base film)
-Raw resin-
Polyester, polystyrene, polystyrene, polyphenylene ether, polyphenylene sulfide, etc. can be used as the raw material resin constituting the base film of the easy-adhesive sheet of the present invention, but polyester is preferred from the viewpoints of cost, mechanical stability and durability.
Examples of the polyester that can be preferably used for the base film include a linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Specific examples of such polyester include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), polyethylene-2,6-naphthalate and the like. Of these, polyethylene terephthalate, polyethylene-2,6-naphthalate, and poly (1,4-cyclohexylenedimethylene terephthalate) are particularly preferable from the viewpoint of balance between mechanical properties and cost.

  The polyester may be a homopolymer or a copolymer. Further, the polyester may be blended with a small amount of another type of resin such as polyimide.

The kind in particular of polyester is not restrict | limited, A well-known thing can be used as polyester.
As polyester used as raw material resin, you may synthesize | combine using a dicarboxylic acid component and a diol component, and may use commercially available polyester.

  When the polyester is synthesized, for example, it can be obtained by subjecting (A) a dicarboxylic acid component and (B) a diol component to an esterification reaction and / or a transesterification reaction by a well-known method.

  (A) Examples of the dicarboxylic acid component include malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, dimer acid, eicosandioic acid, pimelic acid, azelaic acid, methylmalonic acid Aliphatic dicarboxylic acids such as ethylmalonic acid; Alicyclic dicarboxylic acids such as adamantane dicarboxylic acid, norbornene dicarboxylic acid, isosorbide, cyclohexanedicarboxylic acid, decalin dicarboxylic acid; terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalene Dicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, 5-sodiumsulfoisophthalate Acid, phenyl ether Boy carboxylic acid, anthracene dicarboxylic acid, phenanthrene carboxylic, 9,9'-bis (4-carboxyphenyl) aromatic dicarboxylic acids such as fluorene acid; dicarboxylic acids or their ester derivatives, and the like.

  (B) Examples of the dialcohol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 1,3-butanediol, and the like. Aliphatic diols; cycloaliphatic diols such as cyclohexanedimethanol, spiroglycol and isosorbide; bisphenol A, 1,3-benzenedimethanol, 1,4-benzenedimethanol, 9,9′-bis (4-hydroxy Diol compounds such as aromatic diols such as phenyl) fluorene;

(A) As a dicarboxylic acid component, the case where at least 1 sort of aromatic dicarboxylic acid is used is preferable. More preferably, the dicarboxylic acid component contains an aromatic dicarboxylic acid as a main component. The “main component” means that the proportion of aromatic dicarboxylic acid in the dicarboxylic acid component is 80% by mass or more. A dicarboxylic acid component other than the aromatic dicarboxylic acid may be included. Examples of such a dicarboxylic acid component include ester derivatives such as aromatic dicarboxylic acids.
Moreover, it is preferable to use at least one aliphatic diol as the (B) diol component. The aliphatic diol can contain ethylene glycol, and preferably contains ethylene glycol as a main component. The main component means that the proportion of ethylene glycol in the diol component is 80% by mass or more.

  The amount of the aliphatic diol (for example, ethylene glycol) used is in the range of 1.015 to 1.50 mol with respect to 1 mol of the aromatic dicarboxylic acid (for example, terephthalic acid) and, if necessary, its ester derivative. Is preferred. The amount used is more preferably in the range of 1.02 to 1.30 mol, and still more preferably in the range of 1.025 to 1.10 mol. If the amount used is in the range of 1.015 or more, the esterification reaction proceeds favorably, and if it is in the range of 1.50 mol or less, for example, by-production of diethylene glycol due to dimerization of ethylene glycol is suppressed, and the melting point In addition, many properties such as glass transition temperature, crystallinity, heat resistance, hydrolysis resistance, and weather resistance can be kept good.

  Conventionally known reaction catalysts can be used for the esterification reaction and / or the transesterification reaction. Examples of the reaction catalyst include alkali metal compounds, alkaline earth metal compounds, zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium compounds, and phosphorus compounds. Usually, it is preferable to add an antimony compound, a germanium compound, or a titanium compound as a polymerization catalyst at an arbitrary stage before the polyester production method is completed. As such a method, for example, when a germanium compound is taken as an example, it is preferable to add the germanium compound powder as it is.

  For example, in the esterification reaction step, an aromatic dicarboxylic acid and an aliphatic diol are polymerized in the presence of a catalyst containing a titanium compound. In this esterification reaction step, an organic chelate titanium complex having an organic acid as a ligand is used as a catalyst titanium compound, and at least an organic chelate titanium complex, a magnesium compound, and an aromatic ring as a substituent in the step. And a process of adding a pentavalent phosphate ester having no sulfite in this order.

  First, an aromatic dicarboxylic acid and an aliphatic diol are mixed with a catalyst containing an organic chelate titanium complex, which is a titanium compound, prior to the addition of the magnesium compound and the phosphorus compound. Titanium compounds such as organic chelate titanium complexes have high catalytic activity for esterification reactions, so that esterification reactions can be performed satisfactorily. At this time, the titanium compound may be added to the mixture of the dicarboxylic acid component and the diol component, or after mixing the dicarboxylic acid component (or diol component) and the titanium compound, the diol component (or dicarboxylic acid component) is mixed. May be. Further, the dicarboxylic acid component, the diol component, and the titanium compound may be mixed at the same time. The mixing is not particularly limited, and can be performed by a conventionally known method.

  In the polymerization of the polyester, it is also preferable to add the following compound.

As the pentavalent phosphorus compound, at least one pentavalent phosphate having no aromatic ring as a substituent is used. For example, phosphoric acid ester [(OR) ₃ —P═O; R = alkyl group having 1 or 2 carbon atoms] having a lower alkyl group having 2 or less carbon atoms as a substituent can be mentioned. Trimethyl and triethyl phosphate are particularly preferable.

  As an addition amount of a phosphorus compound, the quantity from which P element conversion value becomes the range of 50-90 ppm is preferable. The amount of the phosphorus compound is more preferably 60 to 80 ppm, and even more preferably 60 to 75 ppm.

By including a magnesium compound in the polyester, the electrostatic applicability of the polyester is improved. In this case, coloring may occur, but by adopting the configuration of the present invention, coloring is suppressed, and excellent color tone and heat resistance are obtained.
Examples of the magnesium compound include magnesium salts such as magnesium oxide, magnesium hydroxide, magnesium alkoxide, magnesium acetate, and magnesium carbonate. Among these, magnesium acetate is most preferable from the viewpoint of solubility in ethylene glycol.

  The amount of the magnesium compound added is preferably such that the Mg element conversion value is 50 ppm or more, and more preferably in the range of 50 to 100 ppm, in order to impart high electrostatic applicability. The addition amount of the magnesium compound is preferably an amount in the range of 60 to 90 ppm, more preferably in the range of 70 to 80 ppm in terms of imparting electrostatic applicability.

In the esterification reaction step, the titanium compound as the catalyst component and the magnesium compound and phosphorus compound as the additive are so calculated that the value Z calculated from the following formula (i) satisfies the following relational expression (ii). Particularly preferred is the case of adding and melt polymerizing. Here, the P content is the amount of phosphorus derived from the entire phosphorus compound including the pentavalent phosphate ester having no aromatic ring, and the Ti content is the amount of titanium derived from the entire Ti compound including the organic chelate titanium complex. It is. As described above, by selecting the combined use of the magnesium compound and the phosphorus compound in the catalyst system containing the titanium compound and controlling the addition timing and the addition ratio, while maintaining the catalyst activity of the titanium compound moderately high, yellow A color tone with less taste can be obtained, and heat resistance that hardly causes yellowing can be imparted even when exposed to high temperatures during polymerization reaction or subsequent film formation (during melting).
(I) Z = 5 × (P content [ppm] / P atomic weight) −2 × (Mg content [ppm] / Mg atomic weight) −4 × (Ti content [ppm] / Ti atomic weight)
(Ii) 0 ≦ Z ≦ 5.0
This is an index for quantitatively expressing the balance between the three because the phosphorus compound interacts not only with titanium but also with the magnesium compound.
Formula (i) expresses the amount of phosphorus that can act on titanium by excluding the phosphorus content that acts on magnesium from the total amount of phosphorus that can be reacted. When the value Z is positive, it can be said that there is an excess of phosphorus that inhibits titanium, and conversely, when it is negative, there is a shortage of phosphorus necessary to inhibit titanium. In the reaction, since each atom of Ti, Mg, and P is not equivalent, each mole number in the formula is weighted by multiplying by a valence.

  In the present invention, there is no need for special synthesis or the like, and it is inexpensive and easily obtainable using such a titanium compound, such a phosphorus compound, and a magnesium compound, while having the reaction activity required for the reaction, the color tone. In addition, a polyester excellent in coloring resistance to heat can be obtained.

  In the formula (ii), it is preferable that 1.0 ≦ Z ≦ 4.0 is satisfied from the viewpoint of further enhancing the color tone and heat resistance with heat while maintaining the polymerization reactivity, and 1.5 ≦ Z ≦ 3. The case where 0 is satisfied is more preferable.

  As a preferred embodiment of the present invention, a chelated titanium complex having 1 to 30 ppm of citric acid or citrate as a ligand is added to the aromatic dicarboxylic acid and the aliphatic diol before the esterification reaction is completed. Thereafter, in the presence of the chelated titanium complex, 60 to 90 ppm (more preferably 70 to 80 ppm) of a weak acid magnesium salt is added, and after the addition, 60 to 80 ppm (more preferably 65 to 75 ppm) of It is preferable to add a pentavalent phosphate having no aromatic ring as a substituent.

  The esterification reaction may be carried out using a multistage apparatus in which at least two reactors are connected in series under conditions where ethylene glycol is refluxed while removing water or alcohol produced by the reaction from the system. it can.

The esterification reaction described above may be performed in one stage or may be performed in multiple stages.
When the esterification reaction is performed in one step, the esterification reaction temperature is preferably 230 to 260 ° C, more preferably 240 to 250 ° C.
When the esterification reaction is performed in multiple stages, the temperature of the esterification reaction in the first reaction tank is preferably 230 to 260 ° C, more preferably 240 to 250 ° C, and the pressure is 1.0 to 5.0 kg / cm ² is preferable, and 2.0 to 3.0 kg / cm ² is more preferable. The temperature of the esterification reaction in the second reaction tank is preferably 230 to 260 ° C, more preferably 245 to 255 ° C, and the pressure is 0.5 to 5.0 kg / cm ² , more preferably 1.0 to 3. 0 kg / cm ² . Furthermore, when carrying out by dividing into three or more stages, it is preferable to set the conditions for the esterification reaction in the intermediate stage to the conditions between the first reaction tank and the final reaction tank.

  In polycondensation, a polycondensation product is produced by subjecting an esterification reaction product produced by the esterification reaction to a polycondensation reaction. The polycondensation reaction may be performed in one stage or may be performed in multiple stages.

  The esterification reaction product such as an oligomer generated by the esterification reaction is subsequently subjected to a polycondensation reaction. This polycondensation reaction can be suitably performed by supplying it to a multistage polycondensation reaction tank.

For example, as for the polycondensation reaction conditions in the case of carrying out in a three-stage reaction vessel, the reaction temperature of the first reaction vessel is 255 to 280 ° C., more preferably 265 to 275 ° C., and the pressure is 100 to 10 torr (13.3). × 10 ^{−3 to} 1.3 × 10 ⁻³ MPa), more preferably 50 to 20 torr (6.67 × 10 ^{−3 to} 2.67 × 10 ⁻³ MPa), and the second reaction tank is a reaction The temperature is 265 to 285 ° C., more preferably 270 to 280 ° C., and the pressure is 20 to 1 torr (2.67 × 10 ^{−3 to} 1.33 × 10 ⁻⁴ MPa), more preferably 10 to ³ torr (1. 33 × 10 ^{−3 to} 4.0 × 10 ⁻⁴ MPa), and the third reaction vessel in the final reaction vessel has a reaction temperature of 270 to 290 ° C., more preferably 275 to 285 ° C., and a pressure of 10~0.1torr (1.33 × 10 ^-3 ~ .33 × 10 ^-5 MPa), embodiments are preferred and more preferably ^{5~0.5torr (6.67 × 10 -4 ~6.67 ×} 10 -5 MPa).

  Additives such as light stabilizers, antioxidants, UV absorbers, flame retardants, lubricants (fine particles), nucleating agents (crystallization agents), crystallization inhibitors, etc. to the polyester synthesized as described above May further be included.

The polyester resin used as the raw material resin for the film substrate is preferably subjected to solid phase polymerization after polymerization by an esterification reaction. By solid-phase polymerization, it is possible to control the moisture content of the polyester, the crystallinity, the acid value of the polyester, that is, the concentration of the terminal carboxyl group of the polyester, and the intrinsic viscosity.
In particular, the ethylene glycol (EG) gas concentration at the start of solid phase polymerization is preferably higher in the range of 200 to 1000 ppm than the EG gas concentration at the end of solid phase polymerization, more preferably 250 to 800 ppm, and even more preferably 300. It is preferable to carry out solid phase polymerization by increasing the concentration in the range of ˜700 ppm. At this time, AV can be controlled by adding an average EG gas concentration (average gas concentration at the start and end of solid-phase polymerization). That is, AV can be reduced by reaction with terminal COOH by adding EG. The EG is preferably 100 to 500 ppm, more preferably 150 to 450 ppm, and still more preferably 200 to 400 ppm.

Moreover, the temperature of solid state polymerization is preferably 180 to 230 ° C, more preferably 190 to 215 ° C, and further preferably 195 to 209 ° C.
The solid phase polymerization time is preferably 10 to 40 hours, more preferably 14 to 35 hours, and further preferably 18 to 30 hours.

-Keteneimine, carbodiimide-
In the present invention, when the raw material resin for the film substrate is polyester, a carbodiimide compound or a ketene imine compound may be included. A carbodiimide compound or a ketene imine compound may be used alone or in combination. This is effective for suppressing deterioration of the polyester after thermostat and maintaining high insulation after thermostat.

The ketene imine and carbodiimide are preferably contained in an amount of 0.1 to 10% by mass, more preferably 0.1 to 4% by mass, and 0.1 to 2% by mass with respect to the polyester. More preferably. By making the content rate of a cyclic carbodiimide compound into the said range, the adhesiveness of the interlayer of a base film and the adhesiveness of a base film and an easily bonding layer can be improved. Moreover, the heat resistance of a base film can be improved.
In addition, when a carbodiimide compound and a ketene imine compound are used together, it is preferable that the sum total of the content rate of two types of compounds exists in the said range.

  Examples of the carbodiimide compound include compounds having one or more carbodiimide groups in the molecule (including polycarbodiimide compounds). Specifically, as the monocarbodiimide compound, dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, Examples include dioctylcarbodiimide, t-butylisopropylcarbodiimide, diphenylcarbodiimide, di-t-butylcarbodiimide, di-β-naphthylcarbodiimide, N, N′-di-2,6-diisopropylphenylcarbodiimide and the like. As the polycarbodiimide compound, those having a degree of polymerization of usually 2 or more, preferably 4 or more and an upper limit of usually 40 or less, preferably 30 or less, are used, U.S. Pat. No. 2,941,956, Japanese Patent Publication No. 47-33279, J. Pat. Org. Chem. 28, p2069-2075 (1963), and Chemical Review 1981, 81, No. 4, p. And those produced by the method described in 619-621 and the like.

  Examples of the organic diisocyanate that is a raw material for producing the polycarbodiimide compound include aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and mixtures thereof. Specifically, 1,5-naphthalene diisocyanate, 4 , 4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,4 A mixture of tolylene diisocyanate and 2,6-tolylene diisocyanate, hexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate And 4,4'-dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, tetramethylxylylene diisocyanate, 2,6-diisopropylphenyl isocyanate, 1,3,5-triisopropylbenzene-2,4-diisocyanate, etc. .

  Specific examples of industrially available polycarbodiimides include carbodilite HMV-8CA (manufactured by Nisshinbo), carbodilite LA-1 (manufactured by Nisshinbo), starbazole P (manufactured by Rhein Chemie), starbactol P100 (manufactured by Rhein Chemie), and stavaxol P400. (Product made by Rhein Chemie), Stabilizer 9000 (made by Rashihi Chemi), etc. are illustrated. The carbodiimide compound can be used alone, but a plurality of compounds can also be mixed and used.

A cyclic carbodiimide compound containing one carbodiimide group in the ring skeleton and having in the molecule at least one cyclic structure in which the first nitrogen and the second nitrogen are bonded by a bonding group functions as a cyclic sealant.
A cyclic carbodiimide compound can be prepared by the method described in International Publication 2011/093478 pamphlet.

  The cyclic carbodiimide compound has a cyclic structure. The cyclic carbodiimide compound may have a plurality of cyclic structures. The cyclic structure has one carbodiimide group (—N═C═N—), and the first nitrogen and the second nitrogen are bonded by a bonding group. One cyclic structure has only one carbodiimide group. For example, when there are a plurality of cyclic structures in the molecule, such as a spiro ring, one cyclic structure bonded to a spiro atom is included in each cyclic structure. As long as it has a carbodiimide group, the compound may have a plurality of carbodiimide groups. The number of atoms in the cyclic structure is preferably 8 to 50, more preferably 10 to 30, further preferably 10 to 20, and particularly preferably 10 to 15.

  Here, the number of atoms in the ring structure means the number of atoms that directly constitute the ring structure, and is, for example, 8 for an 8-membered ring and 50 for a 50-membered ring. This is because if the number of atoms in the cyclic structure is smaller than 8, the stability of the cyclic carbodiimide compound is lowered, and it may be difficult to store and use. From the viewpoint of reactivity, there is no particular restriction on the upper limit of the number of ring members, but cyclic carbodiimide compounds having more than 50 atoms are difficult to synthesize, and the cost may increase significantly. From this viewpoint, the number of atoms in the cyclic structure is preferably 10-30, more preferably 10-20, and particularly preferably 10-15.

As the cyclic carbodiimide compound, it is preferable to use a cyclic carbodiimide compound represented by the following general formula (O-1) or general formula (O-2).
Hereinafter, the preferable structure of the cyclic carbodiimide compound of this invention is demonstrated in order of the following general formula (O-1) and general formula (O-2).

First, the cyclic carbodiimide compound represented by the general formula (O-1) will be described.

In general formula (O-1), R ¹ and R ⁵ each independently represents an alkyl group, an aryl group, or an alkoxy group. R ^{2 to} R ⁴ and R ^{6 to} R ⁸ each independently represent a hydrogen atom, an alkyl group, an aryl group, or an alkoxy group. R ^{1 to} R ⁸ may be bonded to each other to form a ring. X ¹ and X ² each independently represents a single bond, —O—, —CO—, —S—, —SO ₂ —, —NH— or —CH ₂ —. L ¹ represents a divalent linking group.

In the general formula (O-1), R ¹ and R ⁵ each independently represents an alkyl group, an aryl group or an alkoxy group, preferably an alkyl group or an aryl group, or a secondary or tertiary alkyl group or Representing an aryl group is more preferred from the viewpoint of suppressing the reaction between the isocyanate end linked to the terminal of the polyester and the hydroxyl terminal of the polyester and suppressing the thickening, and particularly preferably a secondary alkyl group.

The alkyl group represented by R ¹ and R ⁵ is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms, and an alkyl group having 2 to 6 carbon atoms. It is particularly preferred. The alkyl group represented by R ¹ and R ⁵ may be linear, branched or cyclic, but is branched or cyclic, and isocyanate and polyester linked to the end of the polyester. It is preferable from the viewpoint of suppressing the reaction at the hydroxyl terminal and suppressing thickening. The alkyl group represented by R ¹ and R ⁵ is preferably a secondary or tertiary alkyl group, and more preferably a secondary alkyl group. The alkyl groups represented by R ¹ and R ⁵ are methyl, ethyl, n-propyl, sec-propyl, iso-propyl, n-butyl, tert-butyl, sec-butyl, iso-butyl. Group, n-pentyl group, sec-pentyl group, iso-pentyl group, n-hexyl group, sec-hexyl group, iso-hexyl group, cyclohexyl group, etc., among them, iso-propyl group, tert group -Butyl group, iso-butyl group, iso-pentyl group, iso-hexyl group and cyclohexyl group are preferable, iso-propyl group, cyclohexyl group and tert-butyl group are more preferable, and iso-propyl group and cyclohexyl group are particularly preferable. .
The alkyl group represented by R ¹ and R ⁵ may further have a substituent, and the substituent is not particularly limited. However, the alkyl group represented by R ¹ and R ⁵ preferably has no further substituent from the viewpoint of reactivity with carboxylic acid.

The aryl group represented by R ¹ and R ⁵ is preferably an aryl group having 6 to 20 carbon atoms, more preferably an aryl group having 6 to 12 carbon atoms, and an aryl group having 6 carbon atoms. Particularly preferred. The aryl group represented by R ¹ and R ⁵ may be an aryl group formed by condensing R ¹ and R ² or condensing R ⁵ and R ^6, but R ¹ and R ⁵ are each represented by R ² It is preferable that the ring is not condensed with R ⁶ . Examples of the aryl group represented by R ¹ and R ⁵ include a phenyl group and a naphthyl group, and among them, a phenyl group is more preferable.
The aryl group represented by R ¹ and R ⁵ may further have a substituent, and the substituent is not particularly limited. However, the aryl group represented by R ¹ and R ⁵ preferably has no further substituent from the viewpoint of reactivity with carboxylic acid.

The alkoxy group represented by R ¹ and R ⁵ is preferably an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxy group having 1 to 12 carbon atoms, and an alkoxy group having 2 to 6 carbon atoms. It is particularly preferred. The alkoxy group represented by R ¹ and R ⁵ may be linear, branched or cyclic, but is branched or cyclic, and isocyanate and polyester linked to the end of the polyester. It is preferable from the viewpoint of suppressing the reaction at the hydroxyl terminal and suppressing thickening. Preferred examples of alkoxy groups R ¹ and R ⁵ represent, the may include groups terminated -O- is linked alkyl group represented by R ¹ and R ^5, the same preferable ranges R ¹ and R ⁵ It is a group in which —O— is linked to the terminal of a preferred alkyl group.
The alkoxy group represented by R ¹ and R ⁵ may further have a substituent, and the substituent is not particularly limited. However, the alkoxy group represented by R ¹ and R ⁵ preferably has no further substituent from the viewpoint of reactivity with carboxylic acid.

R ¹ and R ⁵ may be the same or different, but are preferably the same from the viewpoint of cost.

In the general formula (O-1), R ^{2 to} R ⁴ and R ^{6 to} R ⁸ each independently represent a hydrogen atom, an alkyl group, an aryl group or an alkoxy group, and a hydrogen atom, an alkyl having 1 to 20 carbon atoms. Group, preferably an alkoxy group having 1 to 20 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and particularly preferably a hydrogen atom.
The alkyl group, aryl group or alkoxy group represented by R ^{2 to} R ⁴ and R ^{6 to} R ⁸ may further have a substituent, and the substituent is not particularly limited.
In the cyclic carbodiimide compound of the present invention, it is preferable that R ² and R ⁶ are both hydrogen atoms in the general formula (O-1) from the viewpoint of easily introducing bulky substituents into R ¹ and R ⁵ . Here, WO2010 / 072111 exemplifies a compound in which an alkyl group or an aryl group is substituted at a site corresponding to R ² and R ⁶ in the general formula (O-1) (meta position with respect to the carbodiimide group). However, these compounds cannot suppress the reaction between the isocyanate linked to the terminal of the polyester and the hydroxyl terminal of the polyester, and in the general formula (O-1), the sites corresponding to R ² and R ⁶ It is difficult to introduce a substituent at (ortho position with respect to the carbodiimide group).

In the general formula (O-1), R ^{1 to} R ⁸ may be bonded to each other to form a ring. The ring formed at this time is not particularly limited, but is preferably an aromatic ring. For example, two or more of R ^{1 to} R ⁴ may be bonded to each other to form a condensed ring, and an arylene group or heteroarylene group having 10 or more carbon atoms is formed together with the benzene ring substituted by R ^{1 to} R ^4. May be. Examples of the arylene group having 10 or more carbon atoms formed at this time include aromatic groups having 10 to 15 carbon atoms such as naphthalenediyl group.
Similarly, for example, two or more of R ^{5 to} R ⁸ may be bonded to each other to form a condensed ring, and an arylene group or heteroarylene having 10 or more carbon atoms together with a benzene ring substituted by R ^{5 to} R ^8. A preferred range at that time is the same as the preferred range when an arylene group or heteroarylene group having 10 or more carbon atoms is formed together with the benzene ring substituted by R ^{1 to} R ⁴ .
However, in the cyclic carbodiimide compound of the present invention, in the general formula (O-1), R ^{1 to} R ⁸ are preferably not bonded to each other to form a ring.

In the general formula (O-1), X ¹ and X ² are each independently selected from a single bond, —O—, —CO—, —S—, —SO ₂ —, —NH—, and —CH ₂ —. At least one selected from the group consisting of —O—, —CO—, —S—, —SO ₂ — and —NH—, among which —O— and —S— are easy to synthesize. From the viewpoint of

In the general formula (O-1), L ¹ represents a divalent linking group, which may contain a heteroatom and a substituent, respectively, a divalent aliphatic group having 1 to 20 carbon atoms, a divalent It is preferably an alicyclic group having 3 to 20 carbon atoms, a divalent aromatic group having 5 to 15 carbon atoms, or a combination thereof, and preferably a divalent aliphatic group having 1 to 20 carbon atoms. More preferred.

Examples of the divalent aliphatic group represented by L ¹ include an alkylene group having 1 to 20 carbon atoms. Examples of the alkylene group having 1 to 20 carbon atoms include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, a dodecylene group, and a hexadecylene group. More preferred are a methylene group, an ethylene group and a propylene group, and an ethylene group is particularly preferred. These aliphatic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

Examples of the divalent alicyclic group represented by L ¹ include a cycloalkylene group having 3 to 20 carbon atoms. Examples of the cycloalkylene group having 3 to 20 carbon atoms include cyclopropylene group, cyclobutylene group, cyclopentylene group, cyclohexylene group, cycloheptylene group, cyclooctylene group, cyclononylene group, cyclodecylene group, cyclododecylene group, and cyclohexadecylene. Group and the like. These alicyclic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

Examples of the divalent aromatic group represented by L ¹ include an arylene group having 5 to 15 carbon atoms, which includes a hetero atom and may have a heterocyclic structure. Examples of the arylene group having 5 to 15 carbon atoms include a phenylene group and a naphthalenediyl group. These aromatic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

In the general formula (O-1), the number of atoms in the cyclic structure containing a carbodiimide group is preferably 8 to 50, more preferably 10 to 30, further preferably 10 to 20, and particularly preferably 10 to 15. .
Here, the number of atoms in the cyclic structure containing a carbodiimide group means the number of atoms that directly constitute the cyclic structure containing a carbodiimide group. It is. This is because if the number of atoms in the cyclic structure is smaller than 8, the stability of the cyclic carbodiimide compound is lowered, and it may be difficult to store and use. From the viewpoint of reactivity, there is no particular restriction on the upper limit of the number of ring members, but cyclic carbodiimide compounds having more than 50 atoms are difficult to synthesize, and the cost may increase significantly. From this viewpoint, in the general formula (O-1), the number of atoms in the cyclic structure is preferably 10 to 30, more preferably 10 to 20, and particularly preferably 10 to 15.

Next, the cyclic carbodiimide compound represented by the general formula (O-2) will be described.

In general formula (O-2), R ¹¹ , R ¹⁵ , R ²¹ and R ²⁵ each independently represents an alkyl group, an aryl group or an alkoxy group. R ^{12 to} R ¹⁴ , R ^{16 to} R ¹⁸ , R ^{22 to} R ²⁴ and R ^{26 to} R ²⁸ each independently represent a hydrogen atom, an alkyl group, an aryl group or an alkoxy group. R ^{11 to} R ²⁸ may combine with each other to form a ring. X ¹¹ , X ¹² , X ²¹ and X ²² each independently represent a single bond, —O—, —CO—, —S—, —SO ₂ —, —NH— or —CH ₂ —. L ² represents a tetravalent linking group.

In the general formula (O-2), the preferred ranges of R ¹¹ , R ¹⁵ , R ²¹ and R ²⁵ are the same as the preferred ranges of R ¹ and R ^{5 in} the general formula (O-1).
In the aryl group represented by R ¹¹ , R ¹⁵ , R ²¹ and R ²⁵ , R ¹¹ and R ¹² are condensed, R ¹⁵ and R ¹⁶ are condensed, R ²¹ and R ²² are condensed, or R ²⁵ and R ²⁶ are condensed. Although it may be an aryl group formed, it is preferable that R ¹¹ , R ¹⁵ , R ²¹ and R ²⁵ do not form a ring by condensing with R ¹² , R ¹⁶ , R ²² and R ²⁶ , respectively.
R ¹¹ , R ¹⁵ , R ²¹ and R ²⁵ may be the same or different, but are preferably the same from the viewpoint of cost.

In the general formula (O-2), a preferable range of R ^{12 to} R ¹⁴ , R ^{16 to} R ¹⁸ , R ^{22 to} R ²⁴ and R ^{26 to} R ²⁸ is R ² in the general formula (O-1). to R are the same as the preferred ranges of ⁴ and R ⁶ to R ^8.
Among ^{R 12 ~R 14, R 16 ~R} 18, R 22 ~R 24 and R ²⁶ to R ^28, can R ^12, R ^16, R ²² and R ²⁶ are both hydrogen atoms, R ^11, R ¹⁵ , R ²¹ and R ²⁵ are preferable from the viewpoint of easy introduction of bulky substituents.

  Thus, by introducing a bulky group such as an alkyl group, an aryl group or an alkoxy group in the vicinity of the carbodiimide group, an isocyanate group and a terminal hydroxyl group of the polyester produced after the reaction of the carbodiimide group and the terminal carboxylic acid of the polyester. Can be suppressed. As a result, high molecular weight of the polyester can be suppressed, and generation of chips due to the increase in the viscosity of the polyester as described above can be suppressed.

In the general formula (O-2), R ^{11 to} R ²⁸ may be bonded to each other to form a ring, and a preferable ring range is the above general formula (O-1), in which R ^{1 to} R ⁸ are each other. This is the same as the range of the ring formed by bonding.

In the general formula (O-2), preferred ranges of X ¹¹ , X ¹² , X ²¹ and X ²² are the same as the preferred ranges of X ¹ and X ^{2 in} the general formula (O-1).

In the general formula (O-2), L ² represents a tetravalent linking group, each of which may contain a heteroatom and a substituent, a tetravalent C 1-20 aliphatic group, a tetravalent A alicyclic group having 3 to 20 carbon atoms, a tetravalent aromatic group having 5 to 15 carbon atoms, or a combination thereof is preferable, and a tetravalent aliphatic group having 1 to 20 carbon atoms is preferable. More preferred.

Examples of the tetravalent aliphatic group represented by L ² include an alkanetetrayl group having 1 to 20 carbon atoms. As an alkanetetrayl group having 1 to 20 carbon atoms, methanetetrayl group, ethanetetrayl group, propanetetrayl group, butanetetrayl group, pentanetetrayl group, hexanetetrayl group, heptanetetrayl group, octanetetrayl Group, nonanetetrayl group, decanetetrayl group, dodecanetetrayl group, hexadecanetetrayl group and the like, methanetetrayl group, ethanetetrayl group, propanetetrayl group are more preferable, and ethanetetrayl group is particularly preferable preferable. These aliphatic groups may contain a substituent. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

Examples of the tetravalent alicyclic group represented by L ² include a cycloalkanetetrayl group having 3 to 20 carbon atoms as the alicyclic group. As a cycloalkanetetrayl group having 3 to 20 carbon atoms, a cyclopropanetetrayl group, a cyclobutanetetrayl group, a cyclopentanetetrayl group, a cyclohexanetetrayl group, a cycloheptanetetrayl group, a cyclooctanetetrayl group, a cyclononanetetrayl group Yl group, cyclodecanetetrayl group, cyclododecanetetrayl group, cyclohexadecanetetrayl group and the like. These alicyclic groups may contain a substituent. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an arylene group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

Examples of the tetravalent aromatic group represented by L ² include an arenetetrayl group having 5 to 15 carbon atoms which may include a hetero atom and have a heterocyclic structure. Examples of the C5-C15 arenetetrayl group (tetravalent) include a benzenetetrayl group and a naphthalenetetrayl group. These aromatic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

In the general formula (O-2), two cyclic structures containing a carbodiimide group are included through L ² which is a tetravalent linking group.
The preferred range of the number of atoms in the cyclic structure containing each carbodiimide group in the general formula (O-2) is the preferred range of the number of atoms in the cyclic structure containing the carbodiimide group in the general formula (O-1). It is the same.

The cyclic carbodiimide compound used in the present invention is an aromatic carbodiimide having no ring structure in which the first nitrogen and the second nitrogen of two or more carbodiimide groups are bonded by a linking group in the molecule. The cyclic carbodiimide compound is monocyclic and is preferably represented by the general formula (O-1) from the viewpoint of being hard to thicken.
However, from the viewpoint of suppressing volatilization and suppressing generation of isocyanate gas during production, the cyclic carbodiimide compound of the present invention preferably has a plurality of cyclic structures and is represented by the general formula (O-2). .

It is preferable for the cyclic carbodiimide compound used in the present invention to have a molecular weight of 400 or more because volatility is small and generation of isocyanate gas during production can be suppressed. Further, the upper limit of the molecular weight of the cyclic carbodiimide compound is not particularly limited as long as the effects of the present invention are not impaired, but 1500 or less is preferable from the viewpoint of reactivity with carboxylic acid.
As for the molecular weight of the cyclic carbodiimide compound used for this invention, it is more preferable that it is 500-1200.

Specific examples of the cyclic carbodiimide compound represented by the general formula (O-1) or the general formula (O-2), that is, specific examples of the cyclic carbodiimide compound of the present invention include the following compounds. It is done. However, the present invention is not limited to the following specific examples.

The cyclic carbodiimide compound is preferably a compound having at least one structure (carbodiimide group) represented by —N═C═N— adjacent to the aromatic ring. For example, in the presence of a suitable catalyst. Further, the organic isocyanate can be heated and produced by a decarboxylation reaction. The cyclic carbodiimide compound of the present invention can be synthesized with reference to the method described in JP2011-256337A.
In synthesizing the cyclic carbodiimide compound, a method for introducing a specific bulky substituent at the ortho position of the arylene group adjacent to the first nitrogen and the second nitrogen of the carbodiimide group is not particularly limited. By nitrating alkylbenzene with nitrobenzene having an alkyl group substituted, it is possible to synthesize a cyclic carbodiimide by the method described in WO2011 / 158958.

The base film preferably contains a ketene imine compound. The ketene imine compound may be used alone or in combination with the cyclic carbodiimide compound.
As the ketene imine compound, a ketene imine compound represented by the following general formula (1) is preferably used. Hereinafter, the ketene imine compound represented by the following general formula (1) will be described.

Here, in general formula (1), R ₁ and R ₂ each independently represents an alkyl group, aryl group, alkoxy group, alkoxycarbonyl group, aminocarbonyl group, aryloxy group, acyl group or aryloxycarbonyl group. , R ₃ represents an alkyl group or an aryl group.

The molecular weight of the portion excluding the nitrogen atom of the ketene imine compound and the substituent bonded to the nitrogen atom is preferably 320 or more. That is, in the general formula (1), the molecular weight of the R ₁ —C (═C) —R ₂ group is preferably 320 or more. The molecular weight of the portion excluding the nitrogen atom of the ketene imine compound and the substituent bonded to the nitrogen atom is preferably 320 or more, more preferably 500 to 1500, and even more preferably 600 to 1000. . Thus, the adhesiveness of a polyester film and an easily bonding layer can be improved by making the molecular weight of the part except a nitrogen atom and the substituent couple | bonded with this nitrogen atom into the said range. This is because the portion excluding the nitrogen atom and the substituent bonded to the nitrogen atom has a molecular weight within a certain range, so that the polyester terminal having a certain bulkiness diffuses into the easy-adhesion layer and exhibits the anchoring effect. Because.

The alkyl group represented by R ₁ and R ₂ is preferably an alkyl group having 1 to 20 carbon atoms, and more preferably an alkyl group having 1 to 12 carbon atoms. The alkyl group represented by R ₁ and R ₂ may be linear, branched or cyclic. Examples of the alkyl group represented by R ₁ and R ₂ include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, tert-butyl group, sec-butyl group, iso-butyl group, n- A pentyl group, a sec-pentyl group, an iso-pentyl group, an n-hexyl group, a sec-hexyl group, an iso-hexyl group, a cyclohexyl group, and the like can be given. Of these, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an iso-butyl group, and a cyclohexyl group are more preferable.
The alkyl group represented by R ₁ and R ₂ may further have a substituent. Unless the reactivity of a ketene imine group and a carboxyl group is lowered, the substituent is not particularly limited, and the above substituents can be exemplified similarly. In addition, carbon number of the alkyl group which R < ₁ > and R < ₂ > represent shows carbon number which does not contain a substituent.

The aryl group represented by R ₁ and R ₂ is preferably an aryl group having 6 to 20 carbon atoms, and more preferably an aryl group having 6 to 12 carbon atoms. Examples of the aryl group represented by R ₁ and R ₂ include a phenyl group and a naphthyl group, and among them, a phenyl group is particularly preferable.
The aryl group includes a heteroaryl group. The heteroaryl group refers to a group in which at least one of the ring-constituting atoms of a 5-membered, 6-membered or 7-membered ring exhibiting aromaticity or a condensed ring thereof is substituted with a heteroatom. Examples of the heteroaryl group include imidazolyl group, pyridyl group, quinolyl group, furyl group, thienyl group, benzoxazolyl group, indolyl group, benzimidazolyl group, benzthiazolyl group, carbazolyl group, and azepinyl group. . The hetero atom contained in the heteroaryl group is preferably an oxygen atom, a sulfur atom, or a nitrogen atom, and particularly preferably an oxygen atom or a nitrogen atom.
The aryl group or heteroaryl group represented by R ₁ and R ₂ may further have a substituent, and the substituent is not particularly limited as long as the reactivity between the ketene imine group and the carboxyl group is not lowered. The carbon number of the aryl group or heteroaryl group represented by R ₁ and R ₂ is the number of carbons not including a substituent.

The alkoxy group represented by R ₁ and R ₂ is preferably an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxy group having 1 to 12 carbon atoms, and an alkoxy group having 2 to 6 carbon atoms. It is particularly preferred that The alkoxy group represented by R ₁ and R ₂ may be linear, branched or cyclic. Preferable examples of the alkoxy group represented by R ₁ and R ₂ include a group in which —O— is linked to the terminal of the alkyl group represented by R ₁ and R ₂ . The alkoxy group represented by R ₁ and R ₂ may further have a substituent, and the substituent is not particularly limited as long as the reactivity between the ketene imine group and the carboxyl group is not lowered. In addition, carbon number of the alkoxy group which R < ₁ > and R < ₂ > represent shows carbon number which does not contain a substituent.

The alkoxycarbonyl group represented by R ₁ and R ₂ is preferably an alkoxycarbonyl group having 2 to 20 carbon atoms, more preferably an alkoxycarbonyl group having 2 to 12 carbon atoms, and 2 to 6 carbon atoms. Particularly preferred is an alkoxycarbonyl group. Examples of the alkoxy moiety of the alkoxycarbonyl group represented by R ₁ and R ₂ include the examples of the alkoxy group described above.

The aminocarbonyl group represented by R ₁ and R ₂ is preferably an alkylaminocarbonyl group having 1 to 20 carbon atoms and an arylaminocarbonyl group having 6 to 20 carbon atoms. Preferable examples of the alkylamino part of the alkylaminocarbonyl group include a group in which —NH— is linked to the terminal of the alkyl group represented by R ₁ and R ₂ . The alkylaminocarbonyl group represented by R ₁ and R ₂ may further have a substituent, and the substituent is not particularly limited as long as the reactivity between the ketene imine group and the carboxyl group is not lowered.
Preferable examples of the arylamino moiety of the arylaminocarbonyl group having 6 to 20 carbon atoms include a group in which —NH— is linked to the terminal of the aryl group represented by R ₁ and R ₂ . The arylaminocarbonyl group represented by R ₁ and R ₂ may further have a substituent, and the substituent is not particularly limited as long as the reactivity between the ketene imine group and the carboxyl group is not lowered. In addition, carbon number of the alkylaminocarbonyl group which R < ₁ > and R < ₂ > represent shows carbon number which does not contain a substituent.

The aryloxy group represented by R ₁ and R ₂ is preferably an aryloxy group having 6 to 20 carbon atoms, and more preferably an aryloxy group having 6 to 12 carbon atoms. Examples of the aryl moiety of the aryloxy group represented by R ₁ and R ₂ include the examples of the aryl group described above.

The acyl group represented by R ₁ and R ₂ is preferably an acyl group having 2 to 20 carbon atoms, more preferably an acyl group having 2 to 12 carbon atoms, and an acyl group having 2 to 6 carbon atoms. It is particularly preferred that The acyl group represented by R ₁ and R ₂ may further have a substituent, and the substituent is not particularly limited as long as the reactivity between the ketene imine group and the carboxyl group is not lowered. In addition, carbon number of the acyl group which R < ₁ > and R < ₂ > represent shows carbon number which does not contain a substituent.

Aryloxycarbonyl group represented by R ₁ and R ₂ is preferably an aryloxycarbonyl group having 7 to 20 carbon atoms, more preferably R ₁ and be an aryloxycarbonyl group having 7 to 12 carbon atoms Examples of the aryl moiety of the aryloxycarbonyl group represented by R ₂ include the examples of the aryl group described above.

R ₃ represents an alkyl group or an aryl group. The alkyl group is preferably an alkyl group having 1 to 20 carbon atoms, and more preferably an alkyl group having 1 to 12 carbon atoms. The alkyl group represented by R ₃ may be linear, branched or cyclic. Examples of the alkyl group represented by R ₃ include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a tert-butyl group, a sec-butyl group, an iso-butyl group, an n-pentyl group, A sec-pentyl group, an iso-pentyl group, an n-hexyl group, a sec-hexyl group, an iso-hexyl group, a cyclohexyl group, and the like can be given. Of these, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, and a cyclohexyl group are more preferable.
The alkyl group represented by R ₃ may further have a substituent. Unless the reactivity of a ketene imine group and a carboxyl group is lowered, the substituent is not particularly limited, and the above substituents can be exemplified similarly.
The aryl group is preferably an aryl group having 6 to 20 carbon atoms, and more preferably an aryl group having 6 to 12 carbon atoms. Examples of the aryl group represented by R ₃ include a phenyl group and a naphthyl group, and among them, a phenyl group is particularly preferable.

The aryl group includes a heteroaryl group. The heteroaryl group refers to a group in which at least one of the ring-constituting atoms of a 5-membered, 6-membered or 7-membered ring exhibiting aromaticity or a condensed ring thereof is substituted with a heteroatom. Examples of the heteroaryl group include imidazolyl group, pyridyl group, quinolyl group, furyl group, thienyl group, benzoxazolyl group, indolyl group, benzimidazolyl group, benzthiazolyl group, carbazolyl group, and azepinyl group. . The hetero atom contained in the heteroaryl group is preferably an oxygen atom, a sulfur atom, or a nitrogen atom, and particularly preferably an oxygen atom or a nitrogen atom.
The aryl group or heteroaryl group represented by R ₃ may further have a substituent, and the substituent is not particularly limited as long as the reactivity between the ketene imine group and the carboxyl group is not lowered.

In addition, General formula (1) may contain the repeating unit. In this case, at least one of R _{1 and} R ₃ is a repeating unit, and this repeating unit preferably contains a ketene imine moiety.

  Moreover, as a ketene imine compound, it is preferable to use the ketene imine compound represented by following General formula (2). Hereinafter, the ketene imine compound represented by the following general formula (2) will be described.

Here, in the general formula (2), R ₁ represents an alkyl group, an aryl group, an alkoxy group, an alkoxycarbonyl group, an aminocarbonyl group, an aryloxy group, an acyl group, or an aryloxycarbonyl group. R ₂ represents an alkyl group having L ₁ as a substituent, an aryl group, an alkoxy group, an alkoxycarbonyl group, an aminocarbonyl group, an aryloxy group, an acyl group, or an aryloxycarbonyl group. R ₃ represents an alkyl group or an aryl group. n represents an integer of 1 to 4, and L ₁ represents an n-valent linking group. The molecular weight of the (R ₁ —C (═C) —R ₂ —) nL ₁ group is preferably 320 or more.

In general formula (2), R ₁ is the same as that in general formula (1), and the preferred range is also the same.

In general formula (2), R ₂ is an alkyl group, aryl group, alkoxy group, alkoxycarbonyl group, aminocarbonyl group, aryloxy group, acyl group or aryloxycarbonyl group having L ₁ which is an n-valent linking group. Represents. The alkyl group, aryl group, alkoxy group, alkoxycarbonyl group, aminocarbonyl group, aryloxy group, acyl group or aryloxycarbonyl group has the same meaning as that in formula (1), and the preferred range is also the same.

In general formula (2), R ₃ is the same as that in general formula (1), and the preferred range is also the same.

L ₁ represents an n-valent linking group, where n represents an integer of 1 to 4. Especially, it is preferable that n is 2-4.
Specific examples of the divalent linking group include, for example, —NR ₈ — (R ₈ represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent, A hydrogen atom is preferred), —SO ₂ —, —CO—, a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkenylene group, an alkynylene group, a substituted or unsubstituted phenylene group, substituted or unsubstituted Examples thereof include a substituted biphenylene group, a substituted or unsubstituted naphthylene group, -O-, -S- and -SO-, and a group obtained by combining two or more thereof.
Specific examples of the trivalent linking group include a group obtained by removing one hydrogen atom from those having a substituent among the linking groups mentioned as examples of the divalent linking group.
Specific examples of the tetravalent linking group include, for example, a group obtained by removing two hydrogen atoms from those having a substituent among the linking groups mentioned as examples of the divalent linking group.

  By setting n to 2 to 4, a compound having two or more ketene imine moieties in one molecule can be obtained, and a more excellent end capping effect can be exhibited. Further, by using a compound having two or more ketene imine moieties in one molecule, the molecular weight per ketene imine group can be lowered, and the ketene imine compound and the terminal carboxyl group of the polyester can be reacted efficiently. Furthermore, it can suppress that a ketene imine compound and a ketene compound volatilize by having two or more ketene imine parts in 1 molecule.

In general formula (2), n is more preferably 3 or 4. By setting n to 3 or 4, a compound having 3 or 4 ketene imine moieties in one molecule can be obtained, and a more excellent end-capping effect can be exhibited. Also, by placing the n 3 or 4, even when the molar molecular weight of the substituents R ₁ or R ₂ in the general formula (2) in the small, it is possible to suppress the volatilization of keteneimines compound.

  As the ketene imine compound, a ketene imine compound represented by the following general formula (3) is preferably used. Hereinafter, the ketene imine compound represented by the following general formula (3) will be described.

In the general formula (3), R ₁ and R ₅ represent an alkyl group, an aryl group, an alkoxy group, an alkoxycarbonyl group, an aminocarbonyl group, an aryloxy group, an acyl group, or an aryloxycarbonyl group. R ₂ and R _{4 each} represents an alkyl group, aryl group, alkoxy group, alkoxycarbonyl group, aminocarbonyl group, aryloxy group, acyl group or aryloxycarbonyl group having L ₂ as a substituent. R ₃ and R ₆ represent an alkyl group or an aryl group. L ₂ represents a single bond or a divalent linking group. _{R 1 -C (= C) -R} 2 -L 2 -R 4 -C (= C) molecular weight of -R ₅ groups is preferably 320 or more.

In general formula (3), R ₁ is the same as that in general formula (1), and the preferred range is also the same. R ₅ is the same as R ₁ in the general formula (1), and the preferred range is also the same.

In general formula (3), R ₂ is the same as that in general formula (2), and the preferred range is also the same. R ₄ is the same as R ₂ in the general formula (2), and the preferred range is also the same.

In general formula (3), R ₃ is the same as that in general formula (1), and the preferred range is also the same. R ₆ is the same as R ₃ in the general formula (1), and the preferred range is also the same.

In General Formula (3), L ₂ represents a single bond or a divalent linking group. Specific examples of the divalent linking group include the linking groups exemplified for L ₁ in formula (2).

  The molecular weight of the portion excluding the nitrogen atom of the ketene imine compound and the substituent bonded to the nitrogen atom is preferably 320 or more. The molecular weight of the portion excluding the nitrogen atom of the ketene imine compound and the substituent bonded to the nitrogen atom may be 320 or more, preferably 400 or more, and more preferably 500 or more. The molar molecular weight of the ketene imine compound relative to the number of ketene imine moieties in one molecule (mole molecular weight / number of ketene imine moieties) is preferably 1000 or less, more preferably 500 or less, and preferably 400 or less. Further preferred. In the present invention, by controlling the molecular weight of the substituent on the ketene imine part carbon of the ketene imine compound and the molar molecular weight of the ketene imine compound relative to the number of ketene imine parts within the above range, the volatilization of the ketene imine compound itself is suppressed, and the terminal carboxyl group of the polyester Volatilization of the ketene compound that occurs when sealing is suppressed, and the terminal carboxyl group of the polyester can be sealed with a low addition amount of ketene imine compound.

  Examples of ketene imine compounds having at least one ketene imine group include those described in J. Org. Am. Chem. Soc. , 1953, 75 (3), pp 657-660, and the like.

  Although the preferable specific example of a ketene imine compound represented by General formula (1) below is shown, this invention is not limited to this.

As shown in the exemplary compound, the ketene imine compound is more preferably trifunctional or tetrafunctional. Thereby, the terminal sealing effect can be improved more and volatilization of a ketene imine compound and a ketene compound can be suppressed effectively.
Also, if having a cyclic structure keteneimines portion as a ring skeleton as exemplified compound (6), R ₁ and R ₃ form a cyclic structure linked, R ₃ is alkylene or arylene group ring skeleton Become. In this case, R ₁ has a linking group containing a ketene imine moiety.
Illustrative compound (10) represents a repeating unit having a repeating number n, and n represents an integer of 3 or more. The left end shown in exemplary compound (10) is a hydrogen atom, and the right end is a phenyl group.

The polyester support used as the substrate film preferably has high hydrolysis resistance. Therefore, the carboxyl group content in the polyester is preferably 50 equivalent / t or less, more preferably 35 equivalent / t or less, and still more preferably 20 equivalent / t or less. When the carboxyl group content is 50 equivalents / t or less, hydrolysis resistance can be maintained, and a decrease in strength when subjected to wet heat aging can be suppressed to be small. The lower limit of the carboxyl group content is 2 equivalents / t, more preferably 3 equivalents / t, and even more preferably 3 equivalents / t in that the adhesion between the layer formed on the polyester (for example, a colored layer) is maintained. Is desirable.
The carboxyl group content in the polyester can be adjusted by polymerization catalyst species, film forming conditions (film forming temperature and time), solid phase polymerization, and additives (end-capping agent, etc.).

-Manufacturing method of substrate film-
Hereinafter, the preferable aspect of the manufacturing method of a base film is demonstrated taking the case where a base film is polyester as an example.
The base film is obtained by, for example, melt-extruding the above polyester into a film shape and then cooling and solidifying it with a casting drum to form an unstretched film. This unstretched film is 1 in the longitudinal direction at Tg to (Tg + 60) ° C. It is a biaxially stretched film that has been stretched so that the total magnification becomes 3 to 6 times twice or more, and then stretched so that the magnification is 3 to 5 times in the width direction at Tg to (Tg + 60) ° C. Is preferred.
Furthermore, what was heat-processed for 1 to 60 second at 180-230 degreeC as needed may be used.
Hereinafter, the preferable aspect of the manufacturing method of a base film is demonstrated.

  In the polyester film forming step, that is, the step of forming the polyester film, the melted material in which the polyester and ketene imine compound, carbodiimide compound, etc. contained in the resin composition are melted is passed through a gear pump or a filter, and then cooled through a die. A film (unstretched) can be formed by extruding into a roll and cooling and solidifying it. Melting is performed using an extruder, but a single screw extruder or a twin screw extruder may be used.

  The carbodiimide or ketene imine compound may be added directly to these extruders, but it is preferable from the viewpoint of extrusion stability to form a polyester and a master batch in advance and put them into the extruder. When forming a masterbatch, it is preferable to give the said fluctuation | variation to the supply amount of the masterbatch containing a ketene imine compound. In addition, it is preferable to use what concentrated the density | concentration of masterbatch ketene imine, and it is preferable from a viewpoint of cost to make 2-100 times the density | concentration in the film after film forming, More preferably, it is 5-50 times.

Extrusion is preferably performed in an evacuated or inert gas atmosphere. Thereby, decomposition | disassembly of a ketene imine, a carbodiimide compound, etc. can be suppressed. The temperature of the extruder is preferably from the melting point of the polyester used to a melting point of + 80 ° C. or less, more preferably a melting point of + 10 ° C. or more, a melting point of + 70 ° C. or less, and even more preferably a melting point of + 20 ° C. or more. If it is less than this range, the resin does not melt sufficiently. On the other hand, if it exceeds this range, polyester, ketene imine compound, carbodiimide compound and the like are decomposed, which is not preferable. In addition, it is preferable to dry master batches, such as polyester, a ketene imine compound, a carbodiimide compound, before this extrusion, and a preferable moisture content is 10-300 ppm, More preferably, it is 20-150 ppm.
The extruded melt is poured on a cast drum through a gear pump, a filter, and a multilayer die. As the multilayer die system, both a multi-manifold die and a feed block die can be preferably used. The shape of the die may be a T-die, a hanger coat die, or a fish tail. It is preferable to give such a temperature fluctuation to the tip (die lip) of such a die.
On the cast drum, the molten resin (melt) can be brought into close contact with the cooling roll using an electrostatic application method. At this time, it is preferable to give the above fluctuation to the driving speed of the cast drum. The surface temperature of the cast drum can be approximately 10 ° C to 40 ° C. The diameter of the cast drum is preferably 0.5 m or more and 5 m or less, more preferably 1 m or more and 4 m or less. The driving speed of the cast drum (the linear speed in the outermost week) is preferably 1 m / min to 50 m / min, more preferably 3 m / min to 30 m / min.

<Extension process>
The (unstretched) film formed by the film forming step can be subjected to a stretching treatment in the stretching step. Stretching is preferably performed in at least one of the machine direction (MD) and the transverse direction (TD), and more preferably, both MD and TD are stretched to balance the physical properties of the film. Such bi-directional stretching may be performed sequentially in the vertical and horizontal directions, or may be performed simultaneously. In the stretching step, the film that has been cooled and solidified with a cooling roll (unstretched) is preferably stretched in one or two directions, and more preferably stretched in two directions. Stretching in two directions (biaxial stretching) includes stretching in the longitudinal direction (MD: Machine Direction) (hereinafter also referred to as “longitudinal stretching”) and stretching in the width direction (TD: Transverse Direction) (hereinafter referred to as “lateral stretching”). It is also preferred that The longitudinal stretching and lateral stretching may each be performed once, or may be performed a plurality of times, and may be simultaneously performed longitudinally and laterally.
The stretching treatment is preferably performed at a glass temperature (Tg) ° C. to (Tg + 60) ° C. of the film, more preferably Tg + 3 ° C. to Tg + 40 ° C., and further preferably Tg + 5 ° C. to Tg + 30 ° C. At this time, it is preferable to provide a temperature distribution as described above.

A preferable draw ratio is 280% to 500%, more preferably 300% to 480%, and further preferably 320% to 460% on at least one side. In the case of biaxial stretching, the film may be stretched uniformly in the vertical and horizontal directions, but it is more preferable to stretch one of the stretch ratios more than the other and unevenly stretch. Either vertical (MD) or horizontal (TD) may be increased. The draw ratio here is determined using the following equation.
Stretch ratio (%) = 100 × {(Length after stretching) / (Length before stretching)

The biaxial stretching treatment is performed, for example, at (Tg ₁ ) ° C. to (Tg ₁ +60) ° C., which is the glass transition temperature of the film, once or twice in the longitudinal direction, so that the total magnification becomes 3 to 6 times. stretched, can then be applied _{(Tg 1) ℃ ~ (Tg} + 60) to the magnification in the width direction at ° C. is three to five times.

In the longitudinal biaxial stretching process, two or more pairs of nip rolls with increased peripheral speed on the outlet side can be used to stretch in the longitudinal direction (longitudinal stretching). You may extend | stretch by widening the space | interval of a longitudinal direction.
Lateral stretching can be performed by holding both ends of the film with a chuck and spreading the film in the orthogonal direction (perpendicular to the longitudinal direction) (lateral stretching).
Simultaneous stretching can be carried out by combining an operation of expanding the chuck interval in the longitudinal direction and an operation of increasing the chuck interval in the width direction after gripping with the chuck.

These stretching steps are preferably combined with an undercoat layer coating step described later. The undercoat layer is preferably formed on the surface of the polyester film by coating before the stretching step or during the stretching step. That is, in the present invention, it is preferable to stretch the polyester film substrate at least once.
For example, the stretching process and the coating process can be performed in the following combinations.
(A) Longitudinal stretching → Coating → Horizontal stretching (b) Coating → Vertical stretching → Horizontal stretching (c) Coating → Vertical and transverse simultaneous stretching (d) Longitudinal stretching → Horizontal stretching → Coating → Vertical stretching (e) Longitudinal stretching → Horizontal Stretching → Coating → Transverse stretching Of these, (a), (b) and (c) are preferred, and (a) is more preferred. This method has the highest adhesion and is preferable because the equipment is compact.

  In the stretching step, the film can be heat-treated before or after the stretching treatment, preferably after the stretching treatment. By performing heat treatment, microcrystals can be generated, and mechanical properties and durability can be improved. The film may be subjected to heat treatment at about 180 to 225 ° C. (more preferably, 185 to 210 ° C.) for 1 to 60 seconds (more preferably 2 to 30 seconds).

In the stretching step, a thermal relaxation treatment can be performed after the heat treatment. The thermal relaxation treatment is a treatment for shrinking the film by applying heat to the film for stress relaxation. The thermal relaxation treatment is preferably performed in both the MD and TD directions of the film. The various conditions in the thermal relaxation treatment are preferably a treatment at a temperature lower than the heat treatment temperature, and preferably 130 to 220 ° C. In the thermal relaxation treatment, the thermal shrinkage rate (150 ° C.) of the film is preferably 1 to 12% for both MD and TD, and more preferably 1 to 10%. For heat shrinkage (150 ° C), a sample with a measurement direction of 350 mm and a width of 50 mm was cut out, marked at 300 mm intervals near both ends in the longitudinal direction of the sample, and fixed at one end to an oven adjusted to a temperature of 150 ° C. The other end is left free for 30 minutes, and then the distance between the gauge points is measured at room temperature. This length is defined as L (mm), and the heat shrinkage rate is obtained by the following formula using the measured value. Can do.
150 ° C. heat shrinkage (%) = 100 × (300−L) / 300
Further, when the thermal contraction rate is positive, it indicates shrinkage, and negative indicates elongation.

  The thickness of the base film is preferably 30 μm or more and 350 μm, more preferably 160 μm or more and 300 μm or less, and still more preferably 180 μm or more and 280 μm or less from the viewpoint of withstand voltage.

  The substrate film preferably has an elongation at break after storage for 50 hours at 120 ° C. and a relative humidity of 100% of 50% or more with respect to the elongation at break before storage (hereinafter referred to as wet under the conditions). The retention of elongation at break before and after the treatment of the heat-treated substrate film is also simply referred to as “break elongation retention”. When the elongation at break is 50% or more, the change accompanying hydrolysis is suppressed, and the adhesive state at the adhesive interface with the coating layer is stably maintained during long-term use. Separation is prevented. Thereby, even when the back sheet is placed over a long period of time under high temperature, high humidity environment or exposure, for example, outdoors, high durability performance is exhibited. More preferably, the time to reach 50% is preferably 75 hours or more and 200 hours or less, more preferably 100 hours or more and 180 hours or less.

  The base film preferably has a breaking strength after heat treatment at 180 ° C. for 50 hours of 50% or more of the breaking strength before heat treatment. More preferably, the breaking strength after heat treatment at 180 ° C. for 80 hours is 50% or more of the breaking strength before heat treatment, and more preferably, the breaking strength after heat treatment at 180 ° C. for 100 hours is 50% of the breaking strength before heat treatment. That's it. Thereby, the heat resistance when exposed to high temperatures can be improved.

  The base film is preferably 1% or less, more preferably 0.5% or less in thermal shrinkage when MD and TD are heat-treated at 150 ° C. for 30 minutes. By maintaining the heat shrinkage at 1% or less, it is possible to prevent warping when the solar cell module is formed.

The base film may be subjected to surface treatment such as corona treatment, flame treatment, and glow discharge treatment as necessary. Of these, corona treatment is a preferred surface treatment method that can be performed at low cost.
Corona discharge treatment is usually performed by applying high frequency and high voltage between a metal roll (dielectric roll) coated with a derivative and an insulated electrode to cause dielectric breakdown of the air between the electrodes. Is ionized to generate a corona discharge between the electrodes. And it performs by passing a base film between this corona discharge.
The preferable processing conditions used in the present invention are preferably a gap clearance of 1 to 3 mm between the electrode and the dielectric roll, a frequency of 1 to 100 kHz, and an applied energy of about 0.2 to 5 kV · A · min / m ² .

The glow discharge treatment is a method called vacuum plasma treatment or glow discharge treatment, in which plasma is generated by discharge in a gas (plasma gas) in a low-pressure atmosphere to treat the substrate surface. The low-pressure plasma used in the process of the present invention is a non-equilibrium plasma generated under conditions where the plasma gas pressure is low. The treatment of the present invention is performed by placing a film to be treated in this low-pressure plasma atmosphere.
In the glow discharge treatment, methods such as direct current glow discharge, high frequency discharge, and microwave discharge can be used as a method for generating plasma. The power source used for discharging may be direct current or alternating current. When alternating current is used, a range of about 30 Hz to 20 MHz is preferable.
When alternating current is used, a commercial frequency of 50 or 60 Hz may be used, or a high frequency of about 10 to 50 kHz may be used. A method using a high frequency of 13.56 MHz is also preferable.

  As the plasma gas used in the glow discharge treatment, an inorganic gas such as oxygen gas, nitrogen gas, water vapor gas, argon gas, and helium gas can be used. In particular, oxygen gas or a mixture of oxygen gas and argon gas can be used. Gas is preferred. Specifically, it is desirable to use a mixed gas of oxygen gas and argon gas. When oxygen gas and argon gas are used, the ratio between the two is preferably about oxygen gas: argon gas = 100: 0 to 30:70, more preferably 90:10 to 70:30, as a partial pressure ratio. In addition, a method is also preferable in which a gas such as the atmosphere entering the processing container due to leakage or water vapor coming out of the object to be processed is used as the plasma gas without introducing the gas into the processing container.

As the pressure of the plasma gas, a low pressure at which non-equilibrium plasma conditions are achieved is necessary. The specific plasma gas pressure is preferably in the range of about 0.005 to 10 Torr, more preferably about 0.008 to 3 Torr. When the pressure of the plasma gas is less than 0.005 Torr, the effect of improving adhesiveness may be insufficient. Conversely, when the pressure exceeds 10 Torr, the current may increase and the discharge may become unstable.
The plasma output cannot be generally specified depending on the shape and size of the processing vessel, the shape of the electrode, and the like, but is preferably about 100 to 2500 W, more preferably about 500 to 1500 W.
The glow discharge treatment time is preferably 0.05 to 100 seconds, more preferably about 0.5 to 30 seconds. If the treatment time is less than 0.05, the adhesion improving effect may be insufficient. Conversely, if the treatment time exceeds 100 seconds, problems such as deformation and coloring of the film to be treated may occur.
Discharge treatment intensity of the glow discharge treatment depends on the plasma power and treatment time, preferably in the range of 0.01~10kV · A · min / m ^2, more preferably 0.1~7kV · A · min / m ^2. Discharge treatment intensity that is sufficient adhesion improving effect of the 0.01 kV · A · min / m ² or more is obtained, and such deformation and coloration of the processed film by a 10 kV · A · min / m ² or less You can avoid problems.
In the glow discharge treatment, it is also preferable to heat the film to be treated in advance. By this method, better adhesiveness can be obtained in a shorter time than when heating is not performed. The heating temperature is preferably in the range of 40 ° C. to the softening temperature of the film to be processed + 20 ° C., more preferably in the range of 70 ° C. to the softening temperature of the film to be processed. By setting the heating temperature to 40 ° C. or higher, a sufficient adhesive improvement effect can be obtained. Moreover, the handleability of a favorable film can be ensured during a process by making heating temperature below into the softening temperature of a to-be-processed film.
Specific methods for raising the temperature of the film to be treated in vacuum include heating with an infrared heater, heating by contacting with a hot roll, and the like.

(Olefin-acrylic composite polymer layer)
The easy-adhesion sheet of the present invention has an olefin-acrylic composite polymer layer that is disposed on at least one side of the base film and includes an olefin resin having an elastic modulus of 320 MPa or less and an acrylic resin.

  The film thickness of the olefin-acrylic composite polymer layer is preferably 30 μm or less, more preferably 1 μm to 20 μm, particularly preferably 1.5 μm to 15 μm, and more preferably 2 to 10 μm. Particularly preferred. By setting the film thickness to 1 μm or more, it is possible to sufficiently exhibit decorativeness and reflectivity, and by setting the film thickness to 30 μm or less, the deterioration of the surface condition is suppressed and the adhesion with the sealing material after aging with wet heat is improved. can do.

-Binder-
In the present invention, as the binder of the olefin-acrylic composite polymer layer, an olefin resin having an elastic modulus of 320 MPa or less (in the present specification, synonymous with olefin resin binder and polyolefin resin) and an acrylic resin binder are used. The ratio of the acrylic resin to the total of the acrylic resin and the olefin resin is in the range of 25 to 55% by mass.

  The ratio of the acrylic resin to the total of the acrylic resin and the olefin resin is preferably in the range of 30 to 55% by mass, and more preferably in the range of 35 to 50% by mass.

(1) Olefin resin Examples of the olefin used in the polyolefin resin include those obtained by polymerizing ethylene, propylene, isobutylene, and the like. Among them, ethylene is preferable. That is, in the easy-adhesion sheet of the present invention, it is preferable that the main chain of the olefin resin binder used for the olefin-acrylic composite polymer layer includes an ethylene unit.
In the easily adhesive sheet of the present invention, the olefin resin binder used in the olefin-acrylic composite polymer layer is preferably a modified olefin resin binder, and more preferably an acid-modified olefin resin binder. The easy-adhesive sheet of the present invention preferably includes a (meth) acrylic acid unit, and particularly preferably includes an acrylic acid unit, as the acidic unit used in the polyolefin resin used in the olefin-acrylic composite polymer layer. Further, in this specification, the acrylic resin includes an acrylate skeleton resin and a methacrylate skeleton resin. Moreover, (meth) acryl means a generic name of acrylic and methacryl, and (meth) acrylate means a generic name of acrylate and methacrylate.
It is preferable that some or all of the acidic units of the polyolefin resin are neutralized with cations. The cation is preferably a metal such as sodium ion, zinc ion, magnesium ion, copper ion, lithium ion or potassium ion, an amine, or ammonia. As the metal ion, sodium ion, zinc ion and the like are preferable. As the amines or ammonia, triethylamine, N, N′-dimethylethanolamine, ammonia and the like are preferable.
Examples of the main chain skeleton of the olefin resin binder include ethylene-acrylic acid ester-maleic anhydride (and / or acrylic acid) copolymer, ethylene-propylene-maleic anhydride (and / or acrylic acid) copolymer Polymer, ethylene-butene-maleic anhydride (and / or acrylic acid) copolymer, propylene-butene-maleic anhydride (and / or acrylic acid) copolymer, ethylene-propylene-butene-maleic anhydride copolymer , Ethylene-propylene-acrylic acid ester-maleic anhydride (and / or acrylic acid) copolymer, ethylene-butene-acrylic acid ester-maleic anhydride (and / or acrylic acid) copolymer, propylene-butene-acrylic Acid ester-maleic anhydride (and / or Acrylic acid) copolymer, ethylene - propylene - butene - acrylic ester - maleic anhydride (and / or acrylic acid) copolymers.
As said polyolefin resin, the polymer which consists of ethylene and acrylic acid or ethylene and methacrylic acid is preferable, for example.
The copolymerization ratio (molar ratio) of the olefin unit and the acid unit in the polyolefin resin is preferably 99.7: 0.3 to 90:10, and preferably 99.5: 0.5 to 97: 3. More preferred.

  In the easy-adhesion sheet of the present invention, the melting point of the olefin resin binder used in the olefin-acrylic composite polymer layer is preferably 75 ° C or higher, more preferably 85 to 105 ° C, and 90 to 95 ° C. It is particularly preferred.

  The elastic modulus of the olefin resin binder used in the present invention is 320 MPa, the elastic modulus of the olefin resin binder is preferably 10 to 250 MPa, more preferably 20 to 150 MPa, and more preferably 30 to 100 MPa. Is particularly preferable, and 30 to 70 MPa is most preferable.

The shape and usage of the olefin resin binder are not particularly limited as long as a polymer layer can be formed. For example, a water-dispersible olefin resin or a meltable olefin resin may be used. Further, it may be a crystalline olefin resin or a non-crystalline olefin resin.
Among them, in the present invention, it is preferable to use an olefin resin binder dispersible in a solvent from the viewpoint of being able to form the olefin-acrylic composite polymer layer by coating, and more improving the adhesion after aging with wet heat. . More preferably, the olefin resin binder is dispersible in water.

  There is no restriction | limiting in particular also about the acquisition method of the said olefin resin binder, You may obtain commercially and may synthesize | combine. Moreover, you may control to the range of the elasticity modulus of the said olefin resin binder calculated | required by this invention by adding an additive.

Examples of commercially available olefin resin binders used in the present invention include Arrow Base SE-1010, SE-1013N, and SD-1010, which are water dispersions obtained by amine-neutralizing ethylene-acrylic acid copolymer. (Both manufactured by Unitika Co., Ltd.), TC-4010 and TD-4010, which are water dispersions obtained by amine neutralization of propylene-acrylic acid copolymer, and ammonia-neutralized ethylene- (meth) acrylic acid copolymer. Hitech S3148, S3121, S8512 (all manufactured by Toho Chemical Co., Ltd.), which is an aqueous dispersion, and Chemipearl S-120, S-75N, V100, EV210H (which is an aqueous dispersion of an ionomer of an ethylene-acrylic acid copolymer) Both of them are manufactured by Mitsui Chemicals, Inc.). Among them, in the present invention, it is preferable to use Arrow Base SE-1013N manufactured by Unitika Ltd. The melting point of Arrow Base SE-1013N is about 91 ° C., and the copolymerization ratio (molar ratio) of the olefin unit and the acid unit is 99: 1.
Moreover, the copolymerization ratio (molar ratio) of the olefin unit and the acidic unit of Hitech S3121 is 95: 5.

  The olefin resin binder used as a binder for the olefin-acrylic composite polymer layer may be used alone, or a plurality of the olefin resin binders may be mixed and used.

(2) Acrylic resin In the easy-adhesion sheet of the present invention, the olefin-acrylic composite polymer layer contains an acrylic resin as a binder.
Examples of the acrylic resin include polymers obtained by copolymerizing monomers having acrylic acid, methacrylic acid and derivatives thereof as components.

  Examples of the (meth) acrylic acid derivative include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth). Acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, t-octyl (meth) acrylate, dodecyl (Meth) acrylate, octadecyl (meth) acrylate, acetoxyethyl (meth) acrylate, phenyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate 2-ethoxyethyl (meth) acrylate, 2- (2-methoxyethoxy) ethyl (meth) acrylate, 3-phenoxy-2-hydroxypropyl (meth) acrylate, benzyl (meth) acrylate, diethylene glycol monomethyl ether (meth) acrylate , Diethylene glycol monoethyl ether (meth) acrylate, diethylene glycol monophenyl ether (meth) acrylate, triethylene glycol monomethyl ether (meth) acrylate, triethylene glycol monoethyl ether (meth) acrylate, polyethylene glycol monomethyl ether (meth) acrylate, polyethylene Glycol monoethyl ether (meth) acrylate, β-phenoxyethoxyethyl acrylate, nonyl Phenoxypolyethylene glycol (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, trifluoroethyl (meth) acrylate, octafluoropentyl (meth) acrylate Perfluorooctylethyl (meth) acrylate, tribromophenyl (meth) acrylate, tribromophenyloxyethyl (meth) acrylate, and the like.

Examples of the copolymerizable monomer include crotonic acid esters, vinyl esters, maleic acid diesters, fumaric acid diesters, itaconic acid diesters, (meth) acrylamides, styrenes, and vinyl ethers.
Examples of the crotonic acid esters include butyl crotonate and hexyl crotonate.
Examples of the vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl methoxyacetate, vinyl benzoate, and the like.
Examples of the maleic acid diesters include dimethyl maleate, diethyl maleate, and dibutyl maleate.
Examples of the fumaric acid diesters include dimethyl fumarate, diethyl fumarate, dibutyl fumarate and the like.
Examples of the itaconic acid diesters include dimethyl itaconate, diethyl itaconate, and dibutyl itaconate.
Examples of the (meth) acrylamides include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N- n-butylacryl (meth) amide, Nt-butyl (meth) acrylamide, N-cyclohexyl (meth) acrylamide, N- (2-methoxyethyl) (meth) acrylamide, N, N-dimethyl (meth) acrylamide, Examples thereof include N, N-diethyl (meth) acrylamide, N-phenyl (meth) acrylamide, N-benzyl (meth) acrylamide, (meth) acryloylmorpholine, diacetone acrylamide and the like.
Examples of the styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, butyl styrene, hydroxy styrene, methoxy styrene, butoxy styrene, acetoxy styrene, chlorostyrene, dichlorostyrene, bromostyrene, chloro Examples include methylstyrene, hydroxystyrene protected with a group that can be deprotected by an acidic substance (for example, t-Boc and the like), methyl vinylbenzoate, α-methylstyrene, and the like.
Examples of the vinyl ethers include methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, and methoxyethyl vinyl ether.

Among these, as the (meth) acrylic monomer, 2-ethylhexyl (meth) acrylate, hydroxyl acrylate, and (meth) acrylic acid are preferable.
Styrene is preferred as the copolymerizable monomer.
The acrylic resin preferably includes at least an alkyl (meth) acrylate unit, and more preferably includes at least a 2-ethylhexyl (meth) acrylate unit.

The ratio of 2-ethylhexyl (meth) acrylate units in the acrylic resin is preferably 10 to 40%, more preferably 15 to 30% in terms of molar ratio.
The ratio of hydroxyl acrylate units in the acrylic resin is preferably 1 to 10%, more preferably 3 to 8% in terms of molar ratio.
The molar ratio of the (meth) acrylic acid unit in the acrylic resin is preferably 40 to 80%, and more preferably 50 to 70%.
The molar ratio of the styrene unit in the acrylic resin is preferably 1 to 15%, and more preferably 5 to 12%.

(3) Other binder The binder of the said olefin-acrylic composite polymer layer may contain other binders other than the said olefin resin and the said acrylic resin, unless contrary to the meaning of this invention.
Examples of the other binder include a polyurethane-based binder. Examples of the polyurethane binder include Superflex 110 and 460, both of which are manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
The ratio (mass ratio) of the olefin resin binder and the acrylic resin binder to the other binder is preferably 50:50 to 100: 0, and more preferably 80:20 to 100: 0.

-Color pigment-
In the easy-adhesion sheet of the present invention, the olefin-acrylic composite polymer layer is a colored layer containing a color pigment.
The first function of the colored layer is to increase the power generation efficiency of the solar cell module by reflecting the light that reaches the back sheet without being used for power generation by the solar cell in the incident light and returning it to the solar cell. is there. The second function is to improve the decorativeness of the appearance when the solar cell module is viewed from the surface side. In general, when a solar cell module is viewed from the surface side, a back sheet can be seen around the solar cell, and by providing a colored layer on the back sheet, the decorativeness can be improved and the appearance can be improved.

The color pigment used in the olefin-acrylic composite polymer layer is not particularly limited, and may be selected according to required reflectivity, design properties, and the like. For example, titanium oxide which is a white pigment can be preferably used.
Among the colored pigments, at least one selected from titanium oxide, carbon black, titanium black, black composite metal oxide, perylene color pigment, cyanine color pigment and quinacrine color pigment is preferable, and titanium oxide or carbon Black is more preferable, and titanium oxide is preferable from the viewpoint of reflectivity and cost.
Here, the black composite metal oxide is preferably a composite metal oxide containing at least one of iron, manganese, cobalt, chromium, copper, and nickel, and includes cobalt, chromium, iron, manganese, copper, and nickel. Among them, it is more preferable to include two or more, and at least one pigment selected from PBk26, PBk27, PBk28, and PBr34 is more particularly preferable.
The pigment of PBk26 is a complex oxide of iron, manganese and copper, the pigment of PBk-27 is a complex oxide of iron, cobalt and chromium, and PBk-28 is a complex oxide of copper, chromium and manganese. PBr34 is a composite oxide of nickel and iron.
Examples of the cyanine color and quinacdrine color include cyanine green, cyanine blue, quinacrine red, phthalocyanine blue, and phthalocyanine green.
Examples of the perylene color pigment include perylene green and perylene black.

If the colored layer uses, for example, a white pigment as the colored pigment, the function of increasing the power generation efficiency by irregularly reflecting the light passing through the cell out of the sunlight incident from the front surface of the solar cell module and returning it to the cell Have
The light reflectance at a wavelength of 550 nm of the surface (outermost surface) on which the colored layer is disposed of the base film is to control the content and thickness of the colored pigment in the colored layer within the numerical range described above or below. Thus, the reflectance can be adjusted in the direction of increasing.

The volume average particle size of the color pigment is preferably 0.03 μm to 0.9 μm, more preferably 0.2 μm to 0.7 μm. By setting the volume average particle diameter of the color pigment within this range, it is possible to suppress a decrease in light reflection efficiency.
The volume average particle diameter of the color pigment is a value (solvent: water, particle shape: non-spherical, particle refractive index: 2.7, ultrasonic treatment: none) measured by Nikkiso Co., Ltd., Microtrac MT3300EX2.

The preferred content of the colored pigment in the olefin-acrylic composite polymer layer (colored layer) varies depending on the type and average particle size of the color pigment to be used. If the content of the colored pigment in the colored layer is not too small, If it is not too much, it is preferable from the viewpoint of adhesiveness with the sealing material. From the viewpoint of sufficiently exerting these functions, in the solar cell protective sheet of the present invention, the content of the color pigment in the colored layer is preferably 2 g / m ^{2 to} 20 g / m ² , more preferably 2 g / m ^2. to 15 g / m ^2, particularly preferably from ^{2g / m 2 ~10g / m 2} .
In the solar cell protective sheet of the present invention, from the same viewpoint, the volume fraction of the colored pigment with respect to all the binders and crosslinking agents contained in the colored layer is preferably 15 to 40%, more preferably 15%. It is -34%, Most preferably, it is 17-25%.

-Crosslinking agent-
The olefin-acrylic composite polymer layer contains a crosslinking agent. Details of the crosslinking agent will be described in the description of the composition for forming an olefin-acrylic composite polymer layer described later.

-Other additives-
The olefin-acrylic composite polymer layer can further contain various additives such as a surfactant, fine particles other than the colored pigment, an ultraviolet absorber, an antioxidant, and the like, particularly for forming a colored layer. The colored layer forming composition is preferably prepared using a surfactant for the dispersion stability of the colored pigment.

  As the surfactant, for example, known surfactants such as anionic, cationic, and nonionic surfactants can be used. Specifically, Demole EP (manufactured by Kao Corporation), NAROACTY CL95 [ Sanyo Chemical Industries, Ltd.]. The surfactant may be a single species or a plurality of species.

Examples of the fine particles other than the color pigment include inorganic oxide fillers such as silica, magnesium oxide, and tin oxide. Among these, tin oxide or silica is preferable because the decrease in adhesiveness when exposed to a humid heat atmosphere is small.
The volume average particle size of the inorganic oxide filler is preferably 10 nm to 700 nm, and more preferably 20 nm to 300 nm. By using an inorganic oxide filler having an average particle size within this range, good adhesion between the colored layer and the adjacent layer is obtained, and particularly in a humid heat environment (for example, 85 ° C., relative humidity 85%). Adhesiveness with an adjacent layer (more preferably, a sealing material of a solar cell module, for example, a sealing material layer containing EVA) can be expressed. The volume average particle diameter of the inorganic oxide filler is a value measured by Nikkiso Microtrac FRA.
The shape of the fine particles other than the color pigment is not particularly limited, and a spherical shape, an indefinite shape, a needle shape, or the like can be used.

The content of the fine particles other than the color pigment in the olefin-acrylic composite polymer layer is preferably 5% by mass to 400% by mass with respect to the total mass of the binder resin of the olefin-acrylic composite polymer layer, and 50% by mass. It is more preferable that it is% -300 mass%. When the content of the fine particles is 5% by mass or more, the adhesiveness when exposed to a humid heat atmosphere and the adhesion with the solar cell module sealing material when aged in a humid heat environment are good, When the amount is 400% by mass or less, deterioration of the planar state of the colored layer can be prevented.
In addition, as fine particles other than the inorganic oxide filler, for example, calcium carbonate, magnesium carbonate, or the like may be included.

-Formation of olefin-acrylic composite polymer layer-
The olefin-acrylic composite polymer layer can be formed by a known method and is not particularly limited. For example, the base film may be used as a support to form a solution film or a melt film, and the olefin-acrylic composite polymer layer may be previously formed on another support by a solution film or a melt film. The placed material and the base film may be laminated via an adhesive or the like. Among these, it is preferable that the protective sheet for solar cells of the present invention is formed into a solution by using the base film as a support. The solution casting method is not particularly limited and may be cast casting or coating, but in the easy-adhesion sheet of the present invention, the olefin-acrylic composite polymer layer is formed by coating. It is preferable to be made.
The olefin-acrylic composite polymer layer may be provided not only on one side of the base film but also on both sides. In this case, it is preferable to apply the both sides of the base film.
Moreover, when the said olefin-acrylic composite polymer layer has the other layer mentioned later between the said base film, the said olefin-acrylic composite polymer layer is directly on a base film or on the said other layer. And can be formed by coating.
The composition for forming an olefin-acrylic composite polymer layer for forming the olefin-acrylic composite polymer layer includes an olefin-based binder having at least an elastic modulus of 320 MPa or less, and if necessary, a coloring pigment, other It can be prepared by mixing a binder resin, an inorganic oxide filler, a crosslinking agent, an additive and the like with a coating solvent.

〔solvent〕
The coating solvent is not particularly limited as long as each component constituting the olefin-acrylic composite polymer layer is dispersed or dissolved and can be removed after coating, but water is preferably used, and the olefin-acrylic composite polymer is used. It is preferable that 60 mass% or more in the solvent contained in the composition for layer formation is water. Such an aqueous composition is preferable in that it is difficult to place a load on the environment, and the ratio of water is 60% by mass or more, which is advantageous in terms of explosion-proof property and safety. The proportion of water in the composition for forming an olefin-acrylic composite polymer layer is preferably larger from the viewpoint of environmental burden, and more preferably 70% by mass or more of water in the total solvent. In the easy-adhesion sheet of the present invention, the solvent residual ratio in the olefin-acrylic composite polymer layer is preferably 0.05% by mass or less based on the mass of the olefin-acrylic composite polymer layer (mass of the coating film). 0.025% by mass or less is more preferable, and 0.01% by mass or less is particularly preferable.

[Crosslinking agent]
The olefin-acrylic composite polymer layer forming composition contains a crosslinking agent.
When the composition for forming an olefin-acrylic composite polymer layer contains a crosslinking agent, the binder resin contained in the composition for forming an olefin-acrylic composite polymer layer is crosslinked to form a colored layer having adhesiveness and strength. Can be preferred.
Examples of the crosslinking agent include epoxy-based, isocyanate-based, melamine-based, carbodiimide-based, and oxazoline-based crosslinking agents. Among these, an oxazoline-based cross-linking agent (compound having an oxazoline group) is particularly preferable from the viewpoint of ensuring adhesion after aging with wet heat with the sealing material of the solar cell module.

  The oxazoline-based crosslinking agent has two or more oxazoline groups in the molecule and may be a low molecular compound or a polymer, but the polymer has better adhesion. preferable.

Specific examples of the oxazoline-based crosslinking agent include low-molecular-weight oxazoline-based crosslinking agents such as 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, and 2-vinyl-5- Methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, 2,2′-bis- (2 -Oxazoline), 2,2'-methylene-bis- (2-oxazoline), 2,2'-ethylene-bis- (2-oxazoline), 2,2'-trimethylene-bis- (2-oxazoline), 2 , 2′-tetramethylene-bis- (2-oxazoline), 2,2′-hexamethylene-bis- (2-oxazoline), 2,2′-octamethylene-bis- (2 -Oxazoline), 2,2'-ethylene-bis- (4,4'-dimethyl-2-oxazoline), 2,2'-p-phenylene-bis- (2-oxazoline), 2,2'-m- Phenylene-bis- (2-oxazoline), 2,2′-m-phenylene-bis- (4,4′-dimethyl-2-oxazoline), 2,2 ′-(1,3-phenylene) -bis- ( 2-oxazoline), bis- (2-oxazolinylcyclohexane) sulfide, bis- (2-oxazolinyl norbornane) sulfide, and the like. Furthermore, (co) polymers of these compounds can also be preferably used.
These may be used alone or in combination of two or more.

The polymer oxazoline-based crosslinking agent can be obtained by polymerizing a monomer component containing an addition-polymerizable oxazoline as a constituent component and a monomer copolymerizable with the addition-polymerizable oxazoline.
Examples of the addition polymerizable oxazoline include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2- Preferred examples include isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline. You may use together. Among these, 2-isopropenyl-2-oxazoline is preferable for easy availability and good adhesion. The amount of these addition polymerizable oxazolines used is not particularly limited, but is preferably 5% by mass or more in the monomer component, more preferably 5 to 90% by mass, further preferably 10 to 60% by mass, and 30 to 60% by mass. % Is particularly preferred.
The monomer copolymerizable with the addition-polymerizable oxazoline is preferably selected from those that do not react with the oxazoline group. For example, methyl (meth) acrylate, ethyl (meth) acrylate, n- (meth) acrylate Butyl, isobutyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, lauryl (meth) acrylate , Stearyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, monoesterified product of (meth) acrylic acid and polyethylene glycol, (meth) acrylic acid- 2-Aminoethyl and its salts, caprola of (meth) acrylic acid (Meth) acrylic acid esters such as (meth) acrylic acid-2,2,6,6-tetramethylpiperidine and (meth) acrylic acid-1,2,2,6,6-pentamethylpiperidine; (Meth) acrylates such as sodium (meth) acrylate, potassium (meth) acrylate and ammonium (meth) acrylate; unsaturated nitriles such as acrylonitrile and methacrylonitrile; (meth) acrylamide, N-methylol (meta ) Unsaturated amides such as acrylamide and N- (2-hydroxyethyl) (meth) acrylamide; Vinyl esters such as vinyl acetate and vinyl propionate; Vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; Vinyl chloride, vinyl chloride Halogen-containing α, β-unsaturated aliphatic hydrocarbons such as redene and vinyl fluoride; α, β-unsaturated aromatic hydrocarbons such as styrene, α-methylstyrene and sodium styrenesulfonate, and the like May be used alone or in combination of two or more.
The easy-adhesion sheet of the present invention is preferably a copolymer in which the oxazoline-based crosslinking agent, that is, the compound having the oxazoline group includes a (meth) acrylic acid ester unit.

  The oxazoline-based crosslinking agent is preferably aqueous such as water-soluble and / or water-dispersible from the viewpoint of excellent mixing stability with the aqueous dispersion of the acid-modified polyolefin resin, and more preferably water-soluble. . The polymerization method of the polymer oxazoline-based crosslinking agent is not particularly limited, and a known method can be employed. For example, a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, or the like in an aqueous medium can be used. By these methods, an aqueous solution or an aqueous dispersion can be obtained. It is preferable that the oxazoline-based cross-linking agent of these polymers does not substantially contain a non-volatile aqueous additive to improve adhesion and weather resistance.

  The molecular weight of the polymer oxazoline-based crosslinking agent is preferably 1000 to 80000 in terms of number average molecular weight, more preferably 3000 to 60000, still more preferably 5000 to 40000, particularly preferably 8000 to 30000, most preferably 10,000 to 20000. preferable. When the number average molecular weight is less than 1000, the adhesiveness and weather resistance tend to decrease. When the number average molecular weight exceeds 80000, it is difficult to produce a polymer.

  As the oxazoline-based crosslinking agent, commercially available products may be used. For example, aqueous dispersion type Epocross “K-1010E”, “K-1020E”, “K-1030E”, K2010E, K2020E, K2030E, aqueous solution type WS500, WS700 [Epocross Series manufactured by Nippon Shokubai Co., Ltd.] and the like can be used.

  It is preferable that content of the crosslinking agent with respect to the total of the solid content mass of the olefin resin and the acrylic resin of the olefin-acrylic composite polymer layer forming composition is 10% by mass to 75% by mass, and 15% by mass to 60% by mass. % Is more preferable, and the range of 20% by mass to 50% by mass is particularly preferable. When the content of the cross-linking agent is 5% by mass or more, a sufficient cross-linking effect can be obtained, and a decrease in strength and poor adhesion of the olefin-acrylic composite polymer layer can be suppressed. On the other hand, the pot life fall of the said composition for olefin-acrylic composite polymer layer formation can be prevented because it is 50 mass% or less.

-Catalyst for crosslinking agent-
The olefin-acrylic composite polymer layer preferably contains at least one of the crosslinking agent catalyst. By containing the crosslinking agent catalyst, the crosslinking reaction between the polymer of the olefin-acrylic composite polymer layer and the crosslinking agent is promoted, and the solvent resistance is improved. Moreover, the adhesiveness between an olefin-acrylic composite polymer layer and a base film can also be improved because crosslinking proceeds well.
In particular, when the olefin-acrylic composite polymer layer contains a crosslinking agent having an oxazoline group (also referred to as an oxazoline-based crosslinking agent) as the crosslinking agent, it is preferable to further contain a catalyst for the crosslinking agent.
Examples of the catalyst for the crosslinking agent include onium compounds.

  Preferred examples of the onium compound include ammonium salts, sulfonium salts, oxonium salts, iodonium salts, phosphonium salts, nitronium salts, nitrosonium salts, diazonium salts and the like.

Specific examples of onium compounds include monoammonium phosphate, diammonium phosphate, ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium p-toluenesulfonate, ammonium sulfamate, ammonium imidodisulfonate, tetrabutylammonium chloride, benzyltrimethylammonium chloride. Ammonium salts such as triethylbenzylammonium chloride, tetrabutylammonium tetrafluoride, tetrabutylammonium hexafluoride, tetrabutylammonium perchlorate, tetrabutylammonium sulfate;
Trimethylsulfonium iodide, boron trifluoride trimethylsulfonium, boron tetrafluoride diphenylmethylsulfonium, boron tetrafluoride benzyltetramethylenesulfonium, antimony hexafluoride 2-butenyltetramethylene sulfonium, antimony hexafluoride 3-methyl-2 -Sulfonium salts such as butenyltetramethylenesulfonium;
Oxonium salts such as boron tetrafluoride trimethyloxonium;
Iodonium salts such as diphenyliodonium chloride and boron tetrafluoride diphenyliodonium;
Phosphonium salts such as antimony hexacyanocyanomethyltributylphosphonium, boron tetrafluoride ethoxycarbonylmethyltributylphosphonium;
Nitronium salts such as boron tetrafluoride nitronium; Nitrosonium salts such as boron tetrafluoride nitrosonium;
Diazonium salts such as 4-methoxybenzenediazonium chloride,
Etc.

  Among these, an onium compound is more preferably an ammonium salt, a sulfonium salt, an iodonium salt, or a phosphonium salt from the viewpoint of shortening the curing time, and among these, an ammonium salt is more preferable, and from the viewpoints of safety, pH, and cost. Are preferably phosphoric acid type and benzyl chloride type. More preferably, the onium compound is dibasic ammonium phosphate.

The catalyst for the cross-linking agent in the olefin-acrylic composite polymer layer may be only one type, or two or more types may be used in combination.
The content of the catalyst of the crosslinking agent in the olefin-acrylic composite polymer layer is preferably in the range of 0.1% by mass to 15% by mass with respect to the crosslinking agent in the olefin-acrylic composite polymer layer. The range of 5% by mass to 12% by mass is more preferable, the range of 1% by mass to 10% by mass is particularly preferable, and the range of 2% by mass to 7% by mass is more preferable. The content of the crosslinking agent catalyst with respect to the crosslinking agent being 0.1% by mass or more means that the crosslinking agent catalyst is positively contained, and the crosslinking agent catalyst content. As a result, the cross-linking reaction between the polymer and the cross-linking agent proceeds better and better solvent resistance is obtained. Moreover, it is advantageous at the point of solubility, filterability, and contact | adherence because content of the catalyst of the said crosslinking agent is 15 mass% or less.

(Application method)
The olefin-acrylic composite polymer layer forming composition can be applied to a base film using a known method such as a gravure coater or a bar coater.
When the composition for forming an olefin-acrylic composite polymer layer contains a color pigment, the volume fraction of the color pigment with respect to the total of the binder resin and the crosslinking agent is 15% to 40% from the viewpoint of reflection performance and film strength. The olefin-acrylic composite polymer layer forming composition is preferably applied on the base film so that the coating thickness is 30 μm or less. Further, it is preferable that the coating amount of the coloring pigment is coated to a ^{2g / m 2 ~20g / m 2} .

(Other layers)
-Undercoat layer-
In the solar cell backsheet of the present invention, an undercoat layer may be provided between the base film (support) and a colored layer described later. The thickness of the undercoat layer is preferably in the range of 2 μm or less, more preferably 0.005 μm to 2 μm, and still more preferably 0.01 μm to 1.5 μm. If the thickness is less than 0.005 μm, uneven coating tends to occur, and if it exceeds 2 μm, the film may be inferior in stickiness and workability.

The undercoat layer preferably contains one or more polymers selected from polyolefin resins, acrylic resins, polyester resins, and polyurethane resins.
As the polyolefin resin, for example, a modified polyolefin copolymer is preferable. Commercially available products may be used as the polyolefin resin. For example, Arrow Base SE-1013N, SD-1010, TC-4010, TD-4010 (both manufactured by Unitika Ltd.), Hitech S3148, S3121, S8512 (both manufactured by Toho Chemical Co., Ltd.), Chemipearl S-120, S-75N, V100, EV210H (both manufactured by Mitsui Chemicals, Inc.) and the like. Among them, in the present invention, it is preferable to use Arrow Base SE-1013N, manufactured by Unitika Ltd., which is a terpolymer of low density polyethylene, acrylic acid ester, and maleic anhydride.
As the acrylic resin, for example, a polymer containing polymethyl methacrylate, polyethyl acrylate, or the like is preferable. As the acrylic resin, a commercially available product may be used. For example, AS-563A (manufactured by Daicel Einchem Co., Ltd.) can be preferably used.
As the polyester resin, for example, polyethylene terephthalate (PET), polyethylene-2,6-naphthalate (PEN) and the like are preferable. As the polyester resin, a commercially available product may be used. For example, Vylonal MD-1245 (manufactured by Toyobo Co., Ltd.) can be preferably used.
As said polyurethane resin, carbonate type urethane resin is preferable, for example, For example, Superflex 460 (made by Daiichi Kogyo Seiyaku Co., Ltd.) can be used preferably.
Among these, it is preferable to use polyolefin resin from a viewpoint of ensuring adhesiveness with a base film and the said olefin-acrylic composite polymer layer. These polymers may be used alone or in combination of two or more. When two or more of these polymers are used in combination, a combination of an acrylic resin and a polyolefin resin is preferable.

It is more preferable that the undercoat layer contains a crosslinking agent because the durability of the undercoat layer can be improved. Examples of the crosslinking agent include epoxy-based, isocyanate-based, melamine-based, carbodiimide-based, and oxazoline-based crosslinking agents. Among them, in the polymer sheet of the present invention, the crosslinking agent in the undercoat layer is preferably an oxazoline-based crosslinking agent. As a cross-linking agent having an oxazoline group, Epocros K2010E, K2020E, K2030E, WS-500, WS-700 (all manufactured by Nippon Shokubai Co., Ltd.) and the like can be used.
The addition amount of the crosslinking agent is preferably 0.5 to 30% by mass, more preferably 5 to 20% by mass, and particularly preferably 3% by mass or more and less than 15% by mass with respect to the binder constituting the undercoat layer. . In particular, when the addition amount of the crosslinking agent is 0.5% by mass or more, a sufficient crosslinking effect is obtained while maintaining the strength and adhesiveness of the undercoat layer, and when it is 30% by mass or less, the pot life of the coating liquid Can be kept long, and the coating surface shape can be improved if it is less than 15% by mass.

The undercoat layer preferably contains an anionic or nonionic surfactant. The range of the surfactant that can be used for the undercoat layer is the same as the range of the surfactant that can be used for the white layer. Of these, anionic surfactants are preferred.
When adding a surfactant, the addition amount is preferably 0.1 to 10 mg / m ² , more preferably 0.5 to 3 mg / m ² . When the addition amount of the surfactant is 0.1 mg / m ² or more, the formation of a good layer is suppressed while suppressing the occurrence of repelling, and when it is 10 mg / m ² or less, the base film and the olefin- Adhesion with the acrylic composite polymer layer can be performed satisfactorily.

As a method for coating the undercoat layer, a known coating method is appropriately adopted. For example, any method such as a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, a coating method using a spray or a brush can be used. Moreover, you may immerse a base film in the aqueous liquid of this invention. From the viewpoint of cost, the aqueous liquid of the present invention is preferably applied by a so-called in-line coating method in which a film is coated in the film production process. Specifically, for example, in the production of the coating film, the base film resin is extruded, for example, while being used in combination with an electrostatic adhesion method or the like, cast on a cooling drum to obtain a sheet, and then stretched in the longitudinal direction. Next, after applying the aqueous liquid to one side of the film after the longitudinal stretching, a method such as stretching in the transverse direction can be used. The conditions for drying and heat treatment during coating depend on the thickness of the coat and the conditions of the apparatus, but it is preferable that the coating is sent to the stretching step in the perpendicular direction immediately after coating and dried in the preheating zone or stretching zone of the stretching step. In such a case, it is normally performed at about 50 to 250 ° C.
The base film may be subjected to corona discharge treatment or other surface activation treatment.

  The solid content concentration in the aqueous coating solution is preferably 30% by mass or less, and particularly preferably 10% by mass or less. The lower limit of the solid content concentration is preferably 1% by mass, more preferably 3% by mass, and particularly preferably 5% by mass. An undercoat layer having a good surface shape can be formed within the above range.

-Overcoat layer-
The overcoat layer is provided on the surface of the olefin-acrylic composite polymer layer in order to easily adhere the sealing agent (preferably EVA film) for sealing the easily adhesive sheet of the present invention and the solar cell element. It is preferable.
The overcoat layer preferably contains one or more kinds of polymers selected from polyolefin resins, acrylic resins, polyester resins, and polyurethane resins. These resins are preferably used because they easily obtain adhesion.
More specifically, for example, the following resins may be mentioned.

As the acrylic resin, for example, a polymer containing polymethyl methacrylate, polyethyl acrylate, or the like is preferable. As the acrylic resin, a commercially available product may be used. For example, AS-563A (manufactured by Daicel Einchem Co., Ltd.) can be preferably used.
As the polyester resin, for example, polyethylene terephthalate (PET), polyethylene-2,6-naphthalate (PEN) and the like are preferable. As the polyester resin, a commercially available product may be used. For example, Vylonal MD-1245 (manufactured by Toyobo Co., Ltd.) can be preferably used.
As said polyurethane resin, carbonate type urethane resin is preferable, for example, For example, Superflex 460 (made by Daiichi Kogyo Seiyaku Co., Ltd.) can be used preferably.

  As the polyolefin resin, for example, a modified polyolefin copolymer is preferable. This is because when an easy-adhesive sheet produced according to the present invention is used as a solar battery backsheet, if an overcoat layer containing a modified polyolefin resin is provided, the olefin resin adjacent to the overcoat layer has high affinity. Because. Commercially available products may be used as the polyolefin resin. For example, Arrow Base SE-1013N, SD-1010, TC-4010, TD-4010 (both manufactured by Unitika Ltd.), Hitech S3148, S3121, S8512 (both manufactured by Toho Chemical Co., Ltd.), Chemipearl S-120, S-75N, V100, EV210H (both manufactured by Mitsui Chemicals, Inc.) and the like. Among them, in the present invention, it is preferable to use Arrow Base SE-1013N, manufactured by Unitika Co., Ltd., which is a terpolymer of low density polyethylene, acrylic acid ester, and maleic anhydride. .

These polyolefin resins may be used alone or in combination of two or more. When two or more are used in combination, a combination of acrylic resin and polyolefin resin, a combination of polyester resin and polyolefin resin, a urethane resin and polyolefin resin. A combination of acrylic resin and polyolefin resin is more preferable.
When used in combination of an acrylic resin and a polyolefin resin, the content of the acrylic resin relative to the total of the polyolefin resin and the acrylic resin in the overcoat layer is preferably 3 to 50% by mass, and 5 to 40% by mass. Is more preferable, and it is especially preferable that it is 7-25 mass%.
A polyester resin (for example, Vylonal MD-1245 (manufactured by Toyobo Co., Ltd.)) can be preferably used in combination with these polyolefin resins, and it is also preferable to add a polyurethane resin to the polyolefin resin. Preferably, for example, Superflex 460 (Daiichi Kogyo Seiyaku Co., Ltd.) can be preferably used.

When the overcoat layer contains a cross-linking agent, the adhesion can be improved, which is more preferable. Examples of the crosslinking agent include epoxy-based, isocyanate-based, melamine-based, carbodiimide-based, and oxazoline-based crosslinking agents. Among them, in the present invention, the crosslinking agent is preferably an oxazoline-based crosslinking agent. As a cross-linking agent having an oxazoline group, Epocros K2010E, K2020E, K2030E, WS-500, WS-700 (all manufactured by Nippon Shokubai Chemical Co., Ltd.) and the like can be used.
The addition amount of the crosslinking agent is preferably 0.5 to 50% by mass, more preferably 3 to 40% by mass, and particularly preferably 5% by mass or more and less than 30% by mass with respect to the binder constituting the overcoat layer. is there. In particular, when the addition amount of the crosslinking agent is 0.5% by mass or more, a sufficient crosslinking effect can be obtained while maintaining the strength and adhesiveness of the overcoat layer. When the life is kept long and the amount is less than 40% by mass, the coated surface can be improved.

  A catalyst for a crosslinking agent can be further added to the overcoat layer. The preferred range of the crosslinker catalyst that can be used in the overcoat layer is the same as the preferred range of the crosslinker catalyst that can be used in the olefin-acrylic composite polymer layer. The oxazoline crosslinker and the onium A combination of compounds is preferred.

The overcoat layer preferably contains an anionic or nonionic surfactant. Of these, anionic surfactants are preferred.
When adding a surfactant, the addition amount is preferably 0.1 to 10 mg / m ² , more preferably 0.5 to 4 mg / m ² . When the surfactant is added in an amount of 0.1 mg / m ² or more, the formation of repellency is suppressed and good layer formation is obtained, and when it is 10 mg / m ² or less, the overcoat layer and the olefin- Adhesion with the acrylic composite polymer layer can be performed satisfactorily.

  The coating solution for forming the overcoat layer may further contain an antistatic agent, a colorant, an ultraviolet absorber and the like.

  The thickness of the overcoat layer may be 0.1 to 5 μm, preferably 0.2 to 3 μm, and more preferably 0.2 to 1.5 μm. In addition, the thickness of an overcoat layer means the average film thickness of an overcoat layer. By making the thickness of the overcoat layer within the above range, the above effect can be easily obtained.

As a method for forming the overcoat layer in the present invention, there is a method by coating. The method by coating is preferable in that it can be formed with a simple and highly uniform thin film. As a coating method, for example, a known method such as a gravure coater or a bar coater can be used. The solvent of the coating solution used for coating may be water or an organic solvent such as toluene or methyl ethyl ketone. A solvent may be used individually by 1 type and may be used in mixture of 2 or more types.
The coating amount of the overcoat layer is preferably 0.1-5 g / m ^2, and more preferably 0.2 to 3 g / m ^2.
Moreover, when forming an overcoat layer by application | coating, it is preferable to serve as both drying and heat processing of an overcoat layer in the drying zone after heat processing. The same applies to the case where a colored layer and other functional layers described later are formed by coating.
It is also preferable to perform surface treatment such as corona treatment, glow treatment, atmospheric pressure plasma treatment, flame treatment, UV treatment, etc. before applying the overcoat layer.

  It is preferable to provide a step of drying the overcoat layer after the coating liquid for forming the overcoat layer is applied. The drying step is a step of supplying drying air to the overcoat layer. The average wind speed of the dry air is preferably 5 to 30 m / sec, more preferably 7 to 25 m / sec, and further preferably 9 to 20 m / sec.

-Weatherproof layer-
The easy-adhesive sheet of the present invention further comprises at least one of a fluororesin and a silicone-acrylic composite resin on the surface of the base film opposite to the surface on which the olefin-acrylic composite polymer layer is disposed. It is preferable to have a weathering layer to contain.
The silicone-based composite polymer of the present invention (hereinafter sometimes referred to as “composite polymer”) has a polymer structure that is copolymerized with a — (Si (R ¹ ) (R ² ) —O) _n — moiety in the molecule. A polymer containing a moiety.

In the portion of “— (Si (R ¹ ) (R ² ) —O) _n —” which is a polysiloxane segment in the composite polymer, R ¹ and R ² may be the same or different and can be covalently bonded to the Si atom. Represents a monovalent organic group.
Examples of the “monovalent organic group that can be covalently bonded to the Si atom” represented by R ¹ and R ² include a substituted or unsubstituted alkyl group (eg, methyl group, ethyl group, etc.), substituted or unsubstituted Aryl groups (eg, phenyl group, etc.), substituted or unsubstituted aralkyl groups (eg, benzyl group, phenylethyl etc.), substituted or unsubstituted alkoxy groups (eg: methoxy group, ethoxy group, propoxy group, etc.), A substituted or unsubstituted aryloxy group (eg, phenoxy group), substituted or unsubstituted amino group (eg, amino group, diethylamino group, etc.), mercapto group, amide group, hydrogen atom, halogen atom (eg, chlorine atom) Etc.).
Among them, R ¹ and R ² are each independently an unsubstituted or substituted alkyl group having 1 to 4 carbon atoms (particularly a methyl group or an ethyl group), an unsubstituted or substituted phenyl group, a mercapto group, An unsubstituted amino group and an amide group are preferable.

Specific examples of the — (Si (R ¹ ) (R ² ) —O) _n — moiety (polysiloxane moiety) of the composite polymer include a hydrolysis condensate of dimethyldimethoxysilane, dimethyldimethoxysilane / γ-methacryloxytrimethoxysilane. Hydrolysis condensate, hydrolysis condensate of dimethyldimethoxysilane / vinyltrimethoxysilane, hydrolysis condensate of dimethyldimethoxysilane / 2-hydroxyethyltrimethoxysilane, dimethyldimethoxysilane / 3-glycidoxypropyltriethoxysilane Hydrolysis condensate of dimethyldimethoxysilane / diphenyl / dimethoxysilane / γ-methacryloxytrimethoxysilane.

The — (Si (R ¹ ) (R ² ) —O) _n — moiety (polysiloxane moiety) of the composite polymer may have a linear structure or a branched structure. Furthermore, a part of the molecular chain may form a ring.
The ratio of the — (Si (R ¹ ) (R ² ) —O) _n — moiety (polysiloxane moiety) of the composite polymer is preferably 15 to 85% by mass with respect to the total mass of the composite polymer. A mass% range is particularly preferred.
If the ratio of the polysiloxane moiety is less than 15% by mass, the adhesiveness may be poor when exposed to a moist heat environment, and if it exceeds 85% by mass, the liquid may become unstable.
The molecular weight of the — (Si (R ¹ ) (R ² ) —O) _n — moiety (polysiloxane moiety) of the composite polymer is about 30,000 to 1,000,000 in terms of polystyrene-converted weight average molecular weight, but more preferably about 50,000 to 300,000.

The composite polymer ^{- (Si (R 1) (} R 2) -O) n - moiety may be a known synthetic method is not particularly limited to the method of creating (polysiloxane moiety). Specifically, there is a method of adding an acid to an aqueous solution of an alkoxysilane compound such as dimethylmethoxysilane or dimethylethoxysilane, followed by hydrolysis and condensation.
The polymer structure portion copolymerized with the polysiloxane portion is not particularly limited, and an acrylic polymer, a polyurethane polymer, a polyester polymer, a rubber polymer, or the like can be used. Among these, acrylic polymers are particularly preferable from the viewpoint of durability.

Esters of acrylic acid (eg, ethyl acrylate, butyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, etc.) or methacrylic acid esters (eg: methyl methacrylate, butyl methacrylate, hydroxyethyl acrylate, glycidyl) as monomers constituting the acrylic polymer And polymers composed of methacrylate, dimethylaminoethyl methacrylate and the like. Furthermore, examples of the monomer include carboxylic acids such as acrylic acid, methacrylic acid, and itaconic acid, styrene, acrylonitrile, vinyl acetate, acrylamide, and divinylbenzene.
The acrylic polymer is a polymer obtained by polymerizing one or more of these monomers, and may be a homopolymer or a copolymer.
Specific examples of the acrylic polymer include methyl methacrylate / ethyl acrylate / acrylic acid copolymer, methyl methacrylate / ethyl acrylate / 2-bidroxyethyl methacrylate / methacrylic acid copolymer, methyl methacrylate / butyl acrylate / 2-bidoxy Examples include ethyl methacrylate / methacrylic acid / γ-methacryloxytrimethoxysilane copolymer, methyl methacrylate / ethyl acrylate / glycidyl methacrylate / acrylic acid copolymer, and the like.

As the polyurethane polymer, a polyurethane polymer comprising a polyisocyanate such as toluene diisocyanate, hexamethylene diisocyanate or isophorone diisocyanate and a polyol such as diethylene glycol, triethylene glycol or neopentyl glycol can be preferably used. There is no restriction | limiting in particular in the preparation method of a polyurethane-type polymer, A well-known synthesis method can be used.
Specific examples of the polyurethane polymer include urethane obtained from toluene diisocyanate and diethylene glycol, urethane obtained from toluene diisocyanate and diethylene glycol / neopentyl glycol, and urethane obtained from hexamethylene diisocyanate and diethylene glycol.

As the polyester polymer, a polyester polymer comprising a polycarboxylic acid such as terephthalic acid, isophthalic acid, adipic acid or sulfoisophthalic acid and the polyol described in the polyurethane can be preferably used. There is no restriction | limiting in particular in the production method of a polyester-type polymer, A well-known synthesis method can be used.
Specific examples of polyester polymers include polyesters obtained from terephthalic acid / isophthalic acid and diethylene glycol, polyesters obtained from terephthalic acid / isophthalic acid / sulfoisophthalic acid and diethylene glycol, and adipic acid / isophthalic acid / sulfoisophthalic acid and diethylene glycol. There are polyester etc.

As the rubber polymer, a copolymer of a diene monomer such as butadiene, isoprene or chloroprene and a copolymer of these diene monomer and a monomer such as styrene copolymerizable therewith can be preferably used. There is no restriction | limiting in particular also in the preparation method of a rubber-type polymer, A well-known synthesis method can be used.
Specific examples of the rubber-based polymer include a rubber-based polymer composed of butadiene / styrene / methacrylic acid, a rubber-based polymer composed of butadiene / methyl methacrylate / methacrylic acid, a rubber-based polymer composed of isoprene / methyl methacrylate / methacrylic acid, and chloroprene / acrylonitrile. / There are rubber polymers made of methacrylic acid.

  The polymer constituting the polymer structure portion copolymerized with the polysiloxane portion may be used alone or in combination of two or more. Furthermore, the individual polymers may be homopolymers or copolymers.

  The molecular weight of the polymer structure portion copolymerized with the polysiloxane portion is about 3000 to 1000000 in terms of polystyrene-equivalent weight average molecular weight, and more preferably about 5000 to 300000.

There is no particular limitation on the method for chemically bonding the-(Si (R ¹ ) (R ² ) -O) _n -moiety (polysiloxane moiety) and the polymer structure portion copolymerized with this moiety. A method of polymerizing a part and a polymer structure part copolymerized with this part separately, chemically bonding each polymer, a method of polymerizing a polysiloxane part in advance and graft polymerizing it, a polymerizing a copolymer polymer part in advance There is a method of graft polymerization of a polysiloxane portion. The latter two methods are preferable because they are easy to create. For example, as a method for copolymerizing an acrylic polymer with a polysiloxane portion, there is a method in which a polysiloxane portion obtained by copolymerization of γ-methacryloxytrimethylsilane or the like is prepared, and this and an acrylic monomer are radically polymerized. Further, as a method of copolymerizing polysiloxane with an acrylic polymer portion, there is a method of causing hydrolysis and polycondensation by adding an alkoxysilane compound to an aqueous dispersion of an acrylic polymer containing γ-methacryloxytrimethylsilane.

When the polymer structure portion copolymerized with the polysiloxane portion is an acrylic polymer, a known polymerization method such as emulsion polymerization or bulk polymerization can be used, but ease of synthesis and aqueous polymer dispersion can be obtained. From the viewpoint, emulsion polymerization is particularly preferable.
Moreover, there is no restriction | limiting in particular in the polymerization initiator used for graft polymerization, Well-known polymerization initiators, such as potassium persulfate, ammonium persulfate, and azobisisobutyronitrile, can be used.

  By using the silicone-based composite polymer described above as the binder for the back surface layer, it becomes possible to improve the adhesiveness between the back surface layer and the base film, and the adhesiveness is lowered even after a long period of time. Can be kept small.

  The silicone composite polymer is preferably in the form of an aqueous polymer dispersion (so-called latex). The preferable particle size of the latex of the silicone composite polymer is about 50 to 500 nm, and the preferable concentration is about 15 to 50% by mass.

The silicone composite polymer preferably has a water-affinity functional group such as a carboxyl group, a sulfonic acid group, a hydroxyl group or an amide group when the aqueous polymer is in the form of latex. When the silicone-based composite polymer of the present invention has a carboxyl group, the carboxyl group may be neutralized with sodium, ammonium, amine or the like.
In addition, when used in the form of a latex, an emulsion stabilizer such as a surfactant (eg, anionic or nonionic surfactant) or a polymer (eg, polyvinyl alcohol) may be added to improve the stability. Good. Further, if necessary, a pH adjuster (eg, ammonia, triethylamine, sodium hydrogen carbonate, etc.), preservative (eg: 1,3,5-hexahydro- (2-hydroxyethyl) -s-triazine, 2- (4 -Thiazolyl) benzimidazole, etc.), thickeners (eg: sodium polyacrylate, methylcellulose, etc.), film-forming aids (eg: butyl carbitol acetate, etc.), etc. Also good.

  Some silicone-based composite polymers that can be used in the present invention are commercially available. Specific examples of commercially available products include Ceranate WSA 1060, 1070 (manufactured by DIC Corporation), Polydurex H7620, H7630, H7650 (manufactured by Asahi Kasei Chemicals Corporation) and the like.

  Examples of the fluorine resin contained in the composition for forming a weather resistant layer for forming the weather resistant layer include chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, trifluoroethylene, chloroethylene, and the like. Examples thereof include a trifluoroethylene / ethylene copolymer and a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer. Among these, from the viewpoints of solubility and weather resistance, a chlorotrifluoroethylene / vinyl ether copolymer copolymerized with a vinyl compound is preferable.

Examples of the fluorine-based resin contained in the composition for forming a weather-resistant layer include Obligato SW0011F (manufactured by AGC Co-Tech), Lumiflon LF200 (manufactured by Asahi Glass Co., Ltd.), Zeffle GK570 (manufactured by Daikin Industries, Ltd.), and the like. Can be mentioned.
From the viewpoint of weather resistance and film strength, the content of the fluororesin with respect to the total solid mass of the weather resistant layer forming composition is preferably 40% by mass to 90% by mass, and 50% by mass to 80% by mass. % Is more preferable.

Examples of the silicone-acrylic composite resin contained in the weather resistant layer forming composition include Ceranate WSA1060, WSA1070 (both manufactured by DIC Corporation) and H7620, H7630, H7650 (both manufactured by Asahi Kasei Chemicals Corporation).
The content of the silicone-acrylic composite resin with respect to the total solid content mass of the weather resistant layer forming composition is preferably 40% by mass to 90% by mass, and 50% by mass to 80% by mass from the viewpoint of weather resistance and film strength. More preferably, it is mass%.

The coating amount of the weather-resistant layer forming composition from adhesion standpoint of weatherability and the base film, it is preferable that the ^{0.5g / m 2 ~20g / m 2} , 3g / m 2 ~15g / M ² is more preferable.

Although there is no restriction | limiting in particular in the method for forming the said composition for weather-resistant layer formation, It is preferable to form by application | coating.
As a coating method, for example, a gravure coater or a bar coater can be used.
Water is preferably used as a coating solvent for the weatherable layer forming composition, and 60% by mass or more of the solvent contained in the weatherable layer forming composition is preferably water. The aqueous composition is preferable in that it is difficult to load the environment, and the ratio of water is 60% by mass or more, which is advantageous in terms of explosion-proof property and safety.
The proportion of water in the composition for forming a weather-resistant layer is preferably larger from the viewpoint of environmental burden, and more preferably 70% by mass or more of water in the total solvent.

  The weather-resistant layer may contain various additives such as the inorganic oxide filler and fine particles other than the inorganic oxide filler, an ultraviolet absorber, an antioxidant, and a surfactant.

The layer thickness of the weather resistant layer is preferably 0.5 μm to 15 μm, and more preferably 3 μm to 10 μm. By setting the film thickness to 0.5 μm or more, weather resistance can be sufficiently exhibited, and by setting the film thickness to 15 μm or less, it is possible to suppress deterioration of the surface condition.
The weather-resistant layer may be a single layer or a structure in which two or more layers are laminated. The protective sheet for a solar cell of the present invention preferably has a configuration in which two layers of the weather resistant layer are laminated.

<Characteristics of easy adhesive sheet>
(Light reflectance)
The surface (outermost surface) on which the olefin-acrylic composite polymer layer of the easy-adhesive sheet and solar cell protective sheet of the present invention is disposed preferably has a light reflectance of 65% or more at a wavelength of 550 nm. When the light reflectance is 65% or more, the light that has passed through the cells of the solar battery can be sufficiently returned to the cells, which is preferable in increasing the power generation efficiency. The light reflectance is more preferably 70% or more, particularly preferably 75% or more, and particularly preferably 80% or more.

[Insulating sheet]
The insulating sheet of the present invention includes the easy-adhesive sheet of the present invention, and the olefin-acrylic composite polymer is also provided on the surface of the base film opposite to the surface on which the olefin-acrylic composite polymer layer is disposed. It is characterized in that the layers are arranged. That is, it is also preferable from the viewpoint of improving the insulating property that the olefin-acrylic composite polymer layer (colored layer) is formed on both surfaces of the base film.

[Protective sheet for solar cell]
The solar cell protective sheet of the present invention includes the easy-adhesive sheet of the present invention, and the surface of the base film on which the olefin-acrylic composite polymer layer is disposed has a light reflectance of 70% at a wavelength of 550 nm. It is the above.
In the protective sheet for a solar cell of the present invention, the surface of the base film on which the olefin-acrylic composite polymer layer is disposed preferably has a light reflectance at a wavelength of 550 nm of 75% or more, 80 % Or more is more preferable.

[Backsheet member for solar cell or backsheet for solar cell]
The solar cell backsheet member or solar cell backsheet of the present invention includes the easy-adhesion sheet of the present invention, the insulating sheet of the present invention, or the protective sheet for solar cells of the present invention. Moreover, you may use the protective sheet for solar cells of this invention as it is as a solar cell backsheet member or solar cell backsheet of this invention.

[Laminated body for solar cell]
The laminate for a solar cell of the present invention is directly adhered to a protective sheet for a solar cell and at least the surface of the protective sheet for a solar cell on the olefin-acrylic composite polymer layer side, and has an ethylene-vinyl acetate copolymer weight. And a polymer layer containing polyvinyl butyral.
The protective sheet for solar cell of the present invention has a good adhesion with the sealing material (for example, EVA, PVB, especially EVA) used for the solar cell module on the surface on the olefin-acrylic composite polymer layer side. They can be bonded together without using an agent layer. Further, the solar cell laminate in which a sealing material such as ethylene-vinyl acetate copolymer is directly bonded to at least the surface of the protective sheet for solar cell on the olefin-acrylic composite polymer layer side is a wet heat environment. Even under the lapse of time, the adhesion between the two is good over a long period of time.
Such a solar cell laminate may be used as it is as a sealing material itself for sealing a solar cell element, or may be used as a part of a sealing material for a solar cell module.

[Solar cell module]
The solar cell protective sheet of the present invention is suitable for the production of a solar cell module.
In the solar cell module, for example, a solar cell element that converts sunlight light energy into electric energy is disposed between the transparent substrate on which sunlight is incident and the solar cell backsheet of the present invention described above. The substrate and the backsheet are sealed with a sealing material such as an ethylene-vinyl acetate copolymer.

The members other than the solar cell module, the solar cell, and the back sheet are described in detail in, for example, “Photovoltaic power generation system constituent material” (supervised by Eiichi Sugimoto, Kogyo Kenkyukai, published in 2008).
A first aspect of the solar cell module of the present invention is a transparent front substrate on the side on which sunlight enters, a solar cell element, a sealing material for sealing the solar cell element, and the sealing material. A solar cell backsheet that is disposed on the side opposite to the front substrate and adheres to the sealing material, and the solar cell backsheet is a solar cell backsheet member or a solar cell backsheet of the present invention. And the olefin-acrylic composite polymer layer of the solar cell backsheet member or the solar cell backsheet is directly bonded to the sealing material.
According to a second aspect of the solar cell module of the present invention, a transparent front substrate on which sunlight is incident, a solar cell element, a sealing material for sealing the solar cell element, and the sealing material A solar cell backsheet that is disposed on the opposite side of the front substrate and adheres to the sealing material, and includes the solar cell laminate of the present invention as the solar cell backsheet and the sealing material. It is characterized by that.
Preferably, the solar cell element, the sealing material that seals the solar cell element, the surface protective member that adheres to the sealing material and protects the light-receiving surface side, and the sealing material that adheres to the light-receiving surface are opposite to each other A back surface protection member that protects the side, the sealing material includes an ethylene-vinyl acetate copolymer (EVA), and the back surface protection member is the back sheet for a solar cell of the present invention, the back surface for the solar cell It can be set as the structure which the coloring layer of the sheet | seat adhered directly with the sealing material. If it is such a solar cell module, even if the solar cell backsheet is in a wet heat environment with EVA, it can be in close contact over a long period of time, and a long-life solar cell module can be obtained.

  The transparent front substrate may be appropriately selected from base materials that transmit light as long as the transparent front substrate has light transmittance through which sunlight can pass. From the viewpoint of power generation efficiency, the higher the light transmittance, the better. For such a substrate, for example, a glass substrate, a transparent resin such as an acrylic resin, or the like can be suitably used.

  Examples of the solar cell element include silicon-based materials such as single crystal silicon, polycrystalline silicon, and amorphous silicon, and group III-V such as copper-indium-gallium-selenium, copper-indium-selenium, cadmium-tellurium, and gallium-arsenic. Various known solar cell elements such as II-VI group compound semiconductor systems can be applied.

The features of the present invention will be described more specifically with reference to the following examples.
The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below. Unless otherwise specified, “part” is based on mass.
In addition, the volume average particle diameter was measured using the Nikkiso Co., Ltd. make and Microtrac MT3300EX2.

[Example 1]
<Preparation of base film>
-Synthesis of polyester-
A slurry of 100 kg of high-purity terephthalic acid (manufactured by Mitsui Chemicals Co., Ltd.) and 45 kg of ethylene glycol (manufactured by Nippon Shokubai Co., Ltd.) was previously charged with about 123 kg of bis (hydroxyethyl) terephthalate, temperature 250 ° C., pressure 1.2 The esterification reaction tank maintained at × 10 ⁵ Pa was sequentially supplied over 4 hours, and the esterification reaction was further performed over 1 hour after the completion of the supply. Thereafter, 123 kg of the obtained esterification reaction product was transferred to a polycondensation reaction tank.

  Subsequently, 0.3% by mass of ethylene glycol was added to the polycondensation reaction tank to which the esterification reaction product had been transferred, based on the resulting polymer. After stirring for 5 minutes, an ethylene glycol solution of cobalt acetate and manganese acetate was added to 30 ppm and 15 ppm, respectively, with respect to the resulting polymer. After further stirring for 5 minutes, a 2% by mass ethylene glycol solution of a titanium alkoxide compound was added to 5 ppm with respect to the resulting polymer. Five minutes later, a 10% by mass ethylene glycol solution of ethyl diethylphosphonoacetate was added so as to be 5 ppm with respect to the resulting polymer. Thereafter, while stirring the low polymer at 30 rpm, the reaction system was gradually heated from 250 ° C. to 285 ° C. and the pressure was reduced to 40 Pa. The time to reach the final temperature and final pressure was both 60 minutes. When the predetermined stirring torque was reached, the reaction system was purged with nitrogen, returned to normal pressure, and the polycondensation reaction was stopped. And it discharged to cold water in the shape of a strand, and it cut immediately and produced the polymer pellet (about 3 mm in diameter, about 7 mm in length). The time from the start of decompression to the arrival of the predetermined stirring torque was 3 hours.

  However, the titanium alkoxide compound used was the titanium alkoxide compound (Ti content = 4.44% by mass) synthesized in Example 1 of paragraph No. [0083] of JP-A-2005-340616.

-Solid state polymerization-
The pellets obtained above were held in a vacuum vessel maintained at 40 Pa at a temperature of 220 ° C. for 30 hours for solid phase polymerization.

-Base formation-
The pellets after undergoing solid phase polymerization as described above were melted at 280 ° C. and cast onto a metal drum to prepare an unstretched base having a thickness of about 3 mm. Thereafter, the film was stretched 3.4 times in the longitudinal direction at 90 ° C., and then the coating solution for forming the undercoat layer was applied to the corona-treated surface of the polyethylene terephthalate support so that the coating amount was 5.1 ml / m ^2. After stretching, coating was performed by an in-line coating method before TD stretching to form an undercoat layer having a thickness of 0.1 μm. The TD stretching temperature is 105 ° C., stretched 4.5 times in the TD direction, and heat treatment is performed for 15 seconds at a film surface of 200 ° C. The MD relaxation rate is 5% at 190 ° C., and the TD relaxation rate is 11%. Thermal relaxation was performed in the MD and TD directions to obtain a biaxially stretched polyethylene terephthalate support (hereinafter referred to as “PET base film”) having a thickness of 250 μm.

-Preparation of coating solution 1 for undercoat layer-
Components in the following composition were mixed to prepare an undercoat layer coating solution 1.

(1) Preparation of undercoat layer forming coating solution 1 Each component in the following composition was mixed to prepare an undercoat layer forming coating solution.
<Composition of coating solution>
・ Polyolefin binder: 24.12 parts by mass
(Arrow Base SE-1013N, manufactured by Unitika Ltd., concentration 20% by mass)
・ Oxazoline-based crosslinking agent: 3.90 parts by mass
(Epocross WS-700, manufactured by Nippon Shokubai Co., Ltd., concentration 25% by mass)
・ Fluorine surfactant: 0.19 parts by mass
(Sodium = bis (3, 3, 4, 4, 5, 5, 6, 6-nonafluoro) = 2-sulfonite oxysuccinate, manufactured by Sankyo Chemical Co., Ltd., concentration 1% by mass)
・ Distilled water: 71.80 parts by mass

(2) Formation of undercoat layer Before forming the undercoat layer, one side of the PET base film was subjected to corona treatment under the following conditions.
・ Electrode and dielectric roll gap clearance: 1.6mm
・ Processing frequency: 9.6 kHz
Processing speed: 20 m / min Processing strength: 0.375 kV / A / min / m ²

-Preparation of white inorganic fine particle dispersion 1-
Components in the following composition were mixed, and the mixture was subjected to dispersion treatment with a dynomill type disperser to obtain a white inorganic fine particle dispersion 1 having a volume average particle size of 0.55 μm.
(Composition of white inorganic fine particle dispersion 1)
・ 1000 parts by weight of titanium dioxide [Taipeku CR-95, manufactured by Ishihara Sangyo Co., Ltd., solid content: 100% by mass; white pigment]
-500% by weight of 10% aqueous solution of polyvinyl alcohol (PVA-105) [PVA-105, manufactured by Kuraray Co., Ltd., solid content: 100% by mass]
-Surfactant 12 parts by mass [Demol EP, manufactured by Kao Corporation, solid content: 25% by mass]
-631 parts by weight of distilled water-6.5 parts by weight of preservative [AF337, manufactured by Daito Chemical Co., Ltd., solid content: 3.5%]

-Preparation of coating solution 1 for colored layer-
Components in the following composition were mixed to prepare a colored layer coating solution 1 and an overcoat coating solution 2.
(Composition of coating solution 1 for colored layer)
-White inorganic fine particle dispersion 1 obtained above 305 parts by mass-Polyolefin resin aqueous dispersion <Colored layer binder resin A> 268 parts by mass [Arrow Base SE-1013N, manufactured by Unitika Ltd.,
Solid content: 20.2% by mass]
-Acrylic resin aqueous dispersion << colored layer binder resin B >> 140 parts by mass [AS-563A, manufactured by Daicel Finechem Co., Ltd.,
Solid content: 28% by weight latex]
-Water-soluble oxazoline compound 168 parts by mass [Epocross WS-700, manufactured by Nippon Shokubai Co., Ltd., solid content: 25% by mass]
・ Distilled water 111 parts by mass ・ Fluorosurfactant 8.5 parts by mass
(Sodium = bis (3, 3, 4, 4, 5, 5, 6, 6-nonafluoro) = 2-sulfonite oxysuccinate, manufactured by Fuji Film Fine Chemical Co., Ltd., concentration 1% by mass)

(Composition of coating liquid 2 for overcoat)
Polyolefin resin aqueous dispersion << colored layer binder resin A >> 169 parts by mass [Arrow Base SE-1013N, manufactured by Unitika Ltd.,
Solid content: 20.2% by mass]
-Acrylic resin aqueous dispersion << colored layer binder resin B >> 30 parts by mass [AS-563A, manufactured by Daicel Finechem Co., Ltd.,
Solid content: 28% by weight latex]
Water-soluble oxazoline compound 43 parts by mass [Epocross WS-700, manufactured by Nippon Shokubai Co., Ltd., solid content: 25% by mass]
-743 parts by weight of distilled water-4.8 parts by weight of a fluorosurfactant
(Sodium = bis (3, 3, 4, 4, 5, 5, 6, 6-nonafluoro) = 2-sulfonite oxysuccinate, manufactured by Fuji Film Fine Chemical Co., Ltd., concentration 1% by mass)

-Formation of undercoat layer, colored layer, and overcoat layer-
One side of the PET substrate film on which the undercoat layer is formed is conveyed at a conveyance speed of 80 m / min and subjected to corona discharge treatment under the condition of 730 J / m ² , and then the color pigment (titanium oxide) is 5.5 g / m ^2. The coating solution 1 for the colored layer was applied by a bar coating method so as to be dried at 170 ° C. for 2 minutes. Thereafter, the overcoat coating solution 2 is applied to a coating weight of 0.5 g / m ² and dried at 170 ° C. for 2 minutes, whereby a white color with a dry thickness of 6 μm is formed on one side of the PET base film. A white PET film was obtained in which a layer (olefin-acrylic composite polymer layer) and an overcoat layer having a dry thickness of 0.5 μm were laminated in this order.

-Measurement of elastic modulus of olefin resin binder of colored layer (olefin-acrylic composite polymer layer)-
The elastic modulus of the olefin resin binder used for the colored layer of the white substrate PET film was measured by the following method.
An olefin resin binder single film (film thickness: about 100 microns) was formed on the therapy HP2 (manufactured by Toray Film Processing Co., Ltd.), and gently peeled so as not to stretch only the olefin resin binder single film. The obtained olefin resin binder single film was cut into 5 mm x 50 mm, and a tensile test was performed at a temperature of 25 ° C and 50% in a Tensilon [Orientec RTM-50] with a chuck distance of 20 mm and a crosshead speed of 50 mm / min. Carried out. The obtained data was analyzed with general-purpose test data processing software, and the elastic modulus was calculated from the stress-strain curve.
The obtained results are shown in Table 1 below.

<Formation of weather-resistant layer>
The following weather-resistant layer first layer and the following weather-resistant layer second layer were formed in this order on the surface opposite to the surface on which the white colored layer of the white base PET film was applied.

-Preparation of coating solution for forming weather resistant layer first layer-
Each component shown in the composition of the following weathering layer first layer forming coating solution was mixed to prepare a weathering layer first layer forming coating solution.

(Composition of the coating solution for forming the weather resistant layer first layer)
Acrylic / silicone binder (silicone resin) 188 parts by mass [Ceranate WSA-1070, manufactured by DIC, solid content: 40%]
-Water-soluble oxazoline compound 58 parts by mass [Epocross WS-700, manufactured by Nippon Shokubai Co., Ltd., solid content: 25% by mass]
-9.4 parts by mass of fluorosurfactant
(Sodium = bis (3, 3, 4, 4, 5, 5, 6, 6-nonafluoro) = 2-sulfonite oxysuccinate, manufactured by Fuji Film Fine Chemical Co., Ltd., concentration 1% by mass)
-254 parts by weight of the above-mentioned white inorganic fine particle dispersion-6.2 parts by weight of dibasic ammonium phosphate [secondary ammonium phosphate for food addition, manufactured by Nippon Chemical Industry Co., Ltd., 35% aqueous solution]

-Formation of weather resistant layer first layer-
The surface of the white PET film opposite to the surface coated with the white colored layer was transported at a transport speed of 80 m / min, and a corona discharge treatment was performed under the condition of 730 J / m ² . Then, on the surface on the side subjected to the corona discharge treatment, the above-mentioned coating solution for forming the weather resistant layer first layer is applied so that the amount of titanium oxide is 10.5 g / m ² in the coating amount, It was made to dry at 170 degreeC for 2 minute (s), and the weather resistant layer 1st layer was formed.

-Preparation of coating solution for forming second layer of weather resistant layer-
Each component shown in the composition of the following coating solution for forming a weather resistant layer second layer was mixed to prepare a coating solution for forming a weather resistant layer second layer.

(Composition of coating solution for forming weather resistant layer second layer)
・ 43 parts by mass of fluorine-based binder [Obligato SW0011F, manufactured by AGC Co-Tech, solid content: 36% diluted with water]
Water-soluble oxazoline compound 12 parts by mass [Epocross WS-700, manufactured by Nippon Shokubai Co., Ltd., solid content: 25% by mass]
-Nonionic surfactant 1.5 parts by mass [Naroacty CL95, Sanyo Chemical Industries, Ltd., solid content: 1% aqueous solution]
-1.3 parts by weight of dimmonium phosphate (dimmonium phosphate for food use, manufactured by Nippon Chemical Industry Co., Ltd., 35% aqueous solution)
-Lubricant 25.7 parts by mass [Chemical Pearl W950, manufactured by Mitsui Chemicals, solid content: 5% water dilution]
-Matting agent 5 parts by weight [Snowtex UP, Nissan Chemical Co., Ltd., diluted with 2% solids in water]
・ Silane coupling agent 5 parts by mass [TSL8340, Momentive Performance Japan, 2% solids hydrolyzate]
・ 114 parts by weight of distilled water

-Formation of second layer of weather resistant layer-
The obtained coating solution for forming the weathering layer second layer was applied on the first layer of the weathering layer so that the amount of the fluororesin was 1.5 g / m ² in terms of coating amount, and at 170 ° C. It was dried for 2 minutes to form a weather resistant layer second layer having a dry thickness of 1.5 μm.

  Thus, an undercoat layer, a white colored layer first layer (olefin-acrylic composite polymer), an overcoat layer are provided on one side of the PET base film, and a weather resistant layer first layer is provided on the opposite side of the PET base film. A solar cell protective sheet provided with a second weathering layer was prepared. This solar cell protective sheet was used as the solar cell protective sheet of Example 1.

<Evaluation of solar cell protective sheet>
The sealing agent adhesion of the solar cell protective sheet of Example 1, the sealing agent adhesion after wet heat aging, the reflectance, and the weather resistance were evaluated by the following methods. The obtained results are shown in Table 1 below.

-1. Sealant adhesion before wet heat aging-
The protective sheet for solar cell produced as described above was cut into a width of 10 mm × 300 mm to prepare a sample piece. This sample piece is in the order of glass (Nippon Sheet Glass Co., Ltd. 150 mm × 150 mm), EVA (Hangzhou EVA sheet: F806, cut size: 100 mm × 150 mm), solar cell protective sheet (overcoat layer side facing). It laminated | stacked and it was made to adhere | attach with EVA by pressing using a vacuum laminator (Nisshinbo Co., Ltd. product). The bonding conditions at this time were as follows.
Vacuuming: 4 minutes at 145 ° C. Pressurization: 10 minutes In this way, the specimen for 200 mm from the end of the sample piece is not bonded to EVA, and the sample for adhesion evaluation in which the EVA sheet is bonded to the remaining 100 mm part Obtained.

The EVA non-adhered part (part of 200 mm from one end of the sample piece) and the glass plate of the obtained adhesion evaluation sample are sandwiched between upper and lower clips of Tensilon (RTC-1210A manufactured by ORIENTEC), the peeling angle is 180 °, and the pulling speed is 100 mm / A tensile test was performed in minutes, and the adhesive strength was measured.
Based on the measured adhesive strength, ranking was performed according to the following evaluation criteria. Among these, ranks 4 and 5 are practically acceptable ranges.
(Evaluation criteria)
5: Adhesion was particularly excellent (60 N / 10 mm or more)
4: Adhesion was very good (30 N / 10 mm or more and less than 60 N / 10 mm)
3: Adhesion was good (20 N / 10 mm or more and less than 30 N / 10 mm)
2: Adhesion failure occurred (10N / 10mm or more and less than 20N / 10mm)
1: Adhesion failure was remarkable (less than 10N / 10mm)

-2. Sealant adhesion after wet heat aging-
The solar cell protective sheet prepared as described above is held for 30 hours (wet heat aging) under environmental conditions of 120 ° C. and 100% relative humidity, and then the same method as the sealant adhesion before the aging of wet heat Sample pieces were prepared and the adhesive strength with the EVA sheet was measured and ranked according to the same evaluation criteria. In addition, about the sealing agent adhesiveness after wet heat aging, rank 3 or more is a practically acceptable range, and rank 4 or more is a practically preferable range.
(Evaluation criteria)
7: Adhesion evaluation 5 before wet heat aging, and adhesion retention rate after wet heat aging is 85% or more 6: Adhesion evaluation 5 before wet heat aging, and adhesion retention rate after wet heat aging 80% or more 5: Adhesion Especially excellent (60N / 10mm or more)
4: Adhesion was very good (30 N / 10 mm or more and less than 60 N / 10 mm)
3: Adhesion was good (20 N / 10 mm or more and less than 30 N / 10 mm)
2: Adhesion failure occurred (10N / 10mm or more and less than 20N / 10mm)
1: Adhesion failure was remarkable (less than 10N / 10mm)

-3. Reflectance-
About the protective sheet for solar cells produced as mentioned above, the reflectance with respect to light of 550 nm was measured with the spectrophotometer UV-3100 (made by Shimadzu Corporation). The reflectance of the barium sulfate standard plate was measured as a reference, and the reflectance of the solar cell protective sheet was calculated using this as 100%.

-4. Weather resistance
The YI value (YI-1) of the sample was measured using a spectroscopic color difference meter “Spectro Color Meter SE2000” manufactured by Nippon Denshoku Industries Co., Ltd.
Thereafter, ultraviolet light was irradiated for 48 hours at an illuminance of 900 W / m ² using the light resistance tester “Isuper UV Tester W-151” manufactured by Iwasaki Electric Co., Ltd. . The environmental conditions at the time of ultraviolet light irradiation were 63 ° C. and relative humidity 50%.
Thereafter, the YI value (YI-2) of the sample is measured again using a spectroscopic color difference meter “Spectro Color Meter SE2000” manufactured by Nippon Denshoku Industries Co., Ltd.
Let YI = (YI−2) − (YI−1) be the degree of coloring of the sample.
The obtained values were ranked according to the following evaluation criteria. Among these, ranks 3 to 5 are practically acceptable ranges.
<Evaluation criteria>
5: YI value is less than 3 4: YI value is 3 or more and less than 5 3: YI value is 5 or more and less than 10 2: YI value is 10 or more and less than 20 1: YI value is 20 or more

-5. Overall evaluation
The protective sheets for solar cells produced as described above were comprehensively evaluated according to the following evaluation criteria. Among these, rank 3 or higher is a practically acceptable range, and rank 4 or higher is a more preferable range for practical use.
(Evaluation criteria)
8: Reflectance 75% or more EVA adhesion evaluation 7
7: Reflectance 75% or more EVA adhesion evaluation 6
6: Reflectance 75% or more EVA adhesion evaluation 5
5: Reflectance less than 75% EVA adhesion evaluation 5
4: EVA adhesion evaluation 4
3: EVA adhesion evaluation 3
2: EVA adhesion evaluation 2
1: EVA adhesion evaluation 1

[Examples 2 to 24, Comparative Examples 1 to 12]
The combination of the olefin resin and the acrylic resin binder in the colored layer coating solution 1 is changed to the binder shown below so that the solid content is the same, and further the presence or absence of the undercoat liquid, the presence or absence of the anti-glare layer, the pigment type, the pigment coating amount, Except having changed the pigment ratio and the crosslinking agent type as shown in Table 1 below, the protective sheets for solar cells of Examples 2 to 24 and Comparative Examples 1 to 12 were prepared and evaluated in the same manner as Example 1. Went.
In Table 1 below, “1” described in the column of the weather resistant layer represents the first weather resistant layer, and “2” represents the second weather resistant layer.

(Binder type and main chain structure used in each example and comparative example)
The following olefin resin (resin A) and other resin (resin B) were used as binders for the colored layer in Example 1, and the content ratio (mass%) of resin B to the total of resin A and resin B in Table 1 below. ).
B1: Olefin resin (Arrow Base SE-1013N, manufactured by Unitika Ltd., solid content: 20.2% by mass) and acrylic resin (AS-563A, manufactured by Daicel Finechem Co., Ltd., solid content: 28% by mass latex) Methacrylic acid unit 59%, styrene unit 9%, 2-ethylhexyl acrylate 26%, 2-hydroxyethyl methacrylate 5% (molar ratio));
B3: Olefin resin (Hitech S3148, manufactured by Toho Chemical Co., Ltd., solid content 25%) and acrylic resin (AS-563A, manufactured by Daicel Finechem Co., Ltd., solid content: 28% by mass latex, methacrylic acid unit 59% Styrene unit 9%, 2-ethylhexyl acrylate 26%, 2-hydroxyethyl methacrylate 5% (molar ratio));

B4: Olefin resin (Hitech S3121, manufactured by Toho Chemical Co., Ltd., solid content 25%) and acrylic resin (AS-563A, manufactured by Daicel Finechem Co., Ltd., solid content: 28% by weight latex, methacrylic acid unit 59% Styrene unit 9%, 2-ethylhexyl acrylate 26%, 2-hydroxyethyl methacrylate 5% (molar ratio));
B5: Olefin resin (Chemical S120, Mitsui Chemicals, Inc., solid content 27%) alone; B6: Acrylic resin (John Kuryl PDX7341, manufactured by BASF Corp., solid content 49%) alone;

B7: Olefin resin (Arrow Base SE-1013N, manufactured by Unitika Ltd., solid content: 20.2% by mass) and urethane type (Superflex 460, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., solid content 38.1%) );
B8: Olefin resin (Arrowbase SE-1013N, manufactured by Unitika Co., Ltd., solid content: 20.2% by mass) and vinyl chloride (Vinibrand GV681, Nissin Chemical Co., Ltd., solid content 50%);
B9: Olefin resin (Arrow Base SE-1013N, manufactured by Unitika Ltd., solid content: 20.2% by mass) and polyester (Vironal MD-1200, manufactured by Toyobo Co., Ltd., solid content 34%);

B13 :: Olefin resin (trade name Arrow Base TD-4010, manufactured by Unitika Ltd., solid content 25%, main chain is polypropylene) and acrylic resin (AS-563A, manufactured by Daicel Finechem Corp., solid content: 28) % By weight latex, methacrylic acid unit 59%, styrene unit 9%, 2-ethylhexyl acrylate 26%, 2-hydroxyethyl methacrylate 5% (molar ratio));
B14: Olefin resin (Chemical S120, manufactured by Mitsui Chemicals, solid content 27%) and acrylic resin (AS-563A, manufactured by Daicel FineChem, Inc., solid content: 28% by weight latex, methacrylic acid unit 59% Styrene unit 9%, 2-ethylhexyl acrylate 26%, 2-hydroxyethyl methacrylate 5% (molar ratio));
B15: Acrylic resin (AS-563A, manufactured by Daicel Finechem Co., Ltd., solid content: 28% by weight latex, methacrylic acid unit 59%, styrene unit 9%, 2-ethylhexyl acrylate 26%, 2-hydroxyethyl methacrylate 5% (Molar ratio)) alone;

B16: Olefin resin (Arrowbase SE-1013N, manufactured by Unitika Ltd., solid content: 20.2 mass%) alone B17: the same kind as B1, with the acrylic resin content ratio being 60 mass%;
B18: The same type as B1, with the acrylic resin content ratio being 20% by mass.

B19: Olefin resin (Arrowbase SE-1013N, manufactured by Unitika Ltd., solid content: 20.2 mass%) and acrylic resin (Nipol LX811h, manufactured by Nippon Zeon Co., Ltd., solid content: latex of 50 mass%), 2-ethylhexyl acrylate not contained)

(Types and addition ratios of pigments used in Examples and Comparative Examples)
In Example 5, carbon black (MF5630, manufactured by Dainichi Seika Co., Ltd., solid content: 32% by mass) was used as a color pigment in place of the above titanium oxide.

(Type of crosslinking agent used in each example and comparative example)
The water-soluble carbodiimide compound described in Example 12 in Table 1 below is trade name Carbodilite V-02-L2, manufactured by Nisshinbo Co., Ltd., having a solid content of 40%, and the water dispersion described in Example 13 in Table 1 below. The water-insoluble oxazoline (latex-type oxazoline) compound has a trade name of Epocross K-2030E, manufactured by Nippon Shokubai Co., Ltd., and a solid content of 40%. The coating amount was added so that the number of reaction site equivalents was the same as WS700 used in Example 1.

[Examples 51 to 54]
The coating solution for the overcoat layer was added to the coating solution for the colored layer in the amount shown in Table 2 as the reaction catalyst for the crosslinking agent, dibasic ammonium phosphate (dimmed ammonium phosphate for food addition, manufactured by Nippon Chemical Industry Co., Ltd.). Except having changed 2 to the coating liquid 3 for overcoats, it carried out similarly to Example 1, produced the protective sheet for solar cells of Examples 51-54, and evaluated.

(Composition of overcoat coating solution 3)
・ Polyolefin resin aqueous dispersion << colored layer binder resin A >> 185 parts by mass [Arrow Base SE-1013N, manufactured by Unitika Ltd.,
Solid content: 20.2% by mass]
Acrylic resin aqueous dispersion << colored layer binder resin B >> 19 parts by mass [AS-563A, manufactured by Daicel Finechem Co., Ltd.,
Solid content: 28% by weight latex]
Water-soluble oxazoline compound 43 parts by mass [Epocross WS-700, manufactured by Nippon Shokubai Co., Ltd., solid content: 25% by mass]
・ Distilled water 739 parts by mass. Fluorosurfactant 4.8 parts by mass.
(Sodium = bis (3, 3, 4, 4, 5, 5, 6, 6-nonafluoro) = 2-sulfonite oxysuccinate, manufactured by Fuji Film Fine Chemical Co., Ltd., concentration 1% by mass)

  The evaluation results obtained in each Example and Comparative Example are shown in Table 1 and Table 2 below.

From the said Table 1 and Table 2, it turned out that the protective sheet for solar cells of this invention is excellent in the sealing material adhesiveness especially after wet heat aging compared with the protective sheet for solar cells of a comparative example. Furthermore, it was also found that the solar cell protective sheet of the present invention was good in sealing material adhesion, reflectance and weather resistance before wet heat aging. That is, it was found that the solar cell protective sheet of the present invention was excellent in performance as both a solar cell backsheet member and a solar cell backsheet when comprehensively evaluated.
On the other hand, the solar cell protective sheet of Comparative Example 1 is an embodiment in which an olefin resin binder having an elastic modulus exceeding the range specified in the present invention is used as a binder of the colored layer, and an acrylic resin is not used. It was inferior in sealing material adhesiveness, and when it evaluated comprehensively, it was inferior in performance as a solar cell backsheet.
The solar cell protective sheet of Comparative Example 2 is an embodiment in which an olefin resin binder was not used as the binder of the colored layer, and was particularly poor in sealing material adhesion before and after wet heat aging. Was inferior.
The protective sheets for solar cells of Comparative Examples 3 to 5 are embodiments in which other resins are used in place of acrylic resins as binders for the colored layers, respectively, and all are particularly inferior in sealing material adhesion after wet heat aging. When evaluated, the performance as a solar cell backsheet was inferior.
On the other hand, the protective sheet for solar cell of Comparative Example 6 is an embodiment in which an olefin resin binder having an elastic modulus exceeding the range specified in the present invention is used as the binder of the colored layer, and particularly in the sealing material adhesion after wet heat aging. When it was inferior and comprehensively evaluated, it was inferior in performance as a solar cell backsheet.
The protective sheet for solar cell of Comparative Example 7 is an embodiment in which a colored layer is formed without adding a coloring pigment, and is particularly inferior in sealing material adhesion after wet heat aging. Was inferior. In addition, the reason why the sealing material adhesion after the wet heat aging of the solar cell protective sheet of Comparative Example 7 was bad was that internal destruction of the base material PET had occurred.
The solar cell protective sheet of Comparative Example 8 is an embodiment in which a colored layer is formed without adding a cross-linking agent, and is particularly inferior in sealing material adhesion after wet heat aging. Was inferior.
The solar cell protective sheet of Comparative Example 9 is an embodiment in which an olefin resin binder was not used as the binder of the colored layer, and was particularly poor in sealing material adhesion before and after wet heat aging. Was inferior.
The protective sheet for solar cell of Comparative Example 10 is an embodiment in which an acrylic resin was not used as the binder of the colored layer, and particularly poor in sealing material adhesion after wet heat aging. It was inferior. In addition, the reason why the sealing material adhesion after the wet heat aging of the solar cell protective sheet of Comparative Example 10 was poor was that internal destruction of the base material PET had occurred.
The protective sheet for solar cell of Comparative Example 11 is an aspect in which the content of the acrylic resin with respect to the total binder of the colored layer exceeds the upper limit of the present invention, and is particularly poor in sealing material adhesion after wet heat aging, and comprehensive evaluation Then, performance was inferior as a solar cell backsheet.
The protective sheet for solar cell of Comparative Example 12 is an embodiment in which the content of the acrylic resin relative to the total binder in the colored layer is below the lower limit of the present invention, particularly poor in sealing material adhesion after wet heat aging, and comprehensive evaluation Then, performance was inferior as a solar cell backsheet.

[Examples 25 and 26]
<Manufacture of insulation sheets>
A PET substrate having a thickness of 150 μm was prepared in the same manner except that the thickness of the substrate PET used in Example 1 was 150 μm.
A PET layer with a thickness of 150 μm was used as the base material, and a colored layer (olefin-acrylic composite polymer layer) was applied to both sides of the PET base material instead of providing the first weathering layer and the second weathering layer. Produced the insulating sheet of Example 25 in the same manner as Example 1.
Moreover, in Example 25, except that the amount of the color pigment added to the colored layer (olefin-acrylic composite polymer layer) was changed as shown in Table 3 below, the same procedure as in Example 25 was repeated. An insulating sheet was produced.

[Examples 27 to 30]
The coating solution for the overcoat layer was added to the coating solution for the coloring layer in the amount shown in Table 3 as a reaction catalyst for the crosslinking agent, dibasic ammonium phosphate (dimmonium phosphate for food addition, manufactured by Nippon Chemical Industry Co., Ltd.). Insulating sheets of Examples 51 to 54 were manufactured in the same manner as Example 25 except that 2 was changed to overcoat coating solution 3.

<Evaluation>
The obtained insulating sheets of Examples 25 to 30 were evaluated in the same manner as in Example 1. The results are shown in Table 3 below.

  From the said Table 3, it turned out that the protective sheet for solar cells of this invention is excellent in the sealing material adhesiveness after wet heat aging. Furthermore, it was also found that the solar cell protective sheet of the present invention was good in sealing material adhesion, reflectance and weather resistance before wet heat aging. That is, when the solar cell protective sheet of the present invention was comprehensively evaluated, it was found that the solar cell protective sheet had excellent performance as both a solar cell backsheet member and a solar cell backsheet.

  In addition, as for the protection sheet for solar cells of each Example which is an easily bonding sheet | seat of this invention, the solvent residual rate in the said colored layer (olefin-acrylic composite polymer layer) is the mass (coating film) of the said olefin-acrylic composite polymer layer. It was confirmed that the content was 0.01% by mass or less based on the mass).

[Example 101]
<Production and evaluation of solar cell module>
3 mm thick tempered glass, EVA sheet (RC02B manufactured by Mitsui Chemicals Fabro Co., Ltd.), crystalline solar cell, EVA sheet (RC02B manufactured by Mitsui Chemicals Fabro Co., Ltd.), and each example The thus-prepared solar cell protective sheets were superposed in this order and hot-pressed using a vacuum laminator (Nisshinbo Co., Ltd., vacuum laminating machine) to bond the EVA and each member. At this time, the protective sheet for solar cell of each Example was arrange | positioned so that the white colored layer might contact with an EVA sheet | seat. Moreover, the adhesion method is as follows.
Using a vacuum laminator, vacuum was applied at 150 ° C. for 3 minutes, and then pressure was applied for 10 minutes for adhesion.

  In this way, a crystalline solar cell module was produced. When the power generation operation was performed using the obtained solar cell module, all showed good power generation performance as a solar cell, and stable operation was performed over a long period.

DESCRIPTION OF SYMBOLS 10 Solar cell module 12 Weather resistant layer 2nd layer 14 Weather resistant layer 1st layer 16 Base film 17 Other layers (undercoat layer)
18 Olefin-acrylic composite polymer layer 20 Solar cell element 22 Sealing material 24 Transparent front substrate 31 Back sheet member for solar cell (one aspect of easy-adhesive sheet)
32 Back sheet for solar cell (another aspect of an easily adhesive sheet)

Claims (28)

A base film;
An olefin-acrylic composite polymer layer that is disposed on at least one side of the base film and contains an olefin resin having an elastic modulus of 320 MPa or less, an acrylic resin, a color pigment, and a crosslinking agent;
A ratio of the acrylic resin to the total of the acrylic resin and the olefin resin is in the range of 25 to 55% by mass.   The easy-adhesive sheet according to claim 1, wherein the main chain of the olefin resin is ethylene and includes a (meth) acrylic acid ester unit.   The easily adhesive sheet according to claim 1 or 2, wherein the acrylic resin contains an alkyl (meth) acrylate unit.   The easily adhesive sheet according to claim 1 or 2, wherein the acrylic resin contains a 2-ethylhexyl (meth) acrylate unit.   The easily adhesive sheet according to claim 1, wherein the base film is a polyester film.   It has an undercoat layer containing an olefin resin having an elastic modulus of 320 MPa or less between the base film and the olefin-acrylic composite polymer layer, and easy adhesion according to any one of claims 1 to 5, Sheet.   The easily adhesive sheet according to claim 6, wherein the undercoat layer has a thickness of 2 μm or less.   The easily bonding sheet according to claim 1, wherein the crosslinking agent is a compound having an oxazoline group.   The easily adhesive sheet according to claim 8, wherein the compound having an oxazoline group is water-soluble.   The said olefin-acrylic composite polymer layer WHEREIN: The ratio of the said crosslinking agent with respect to the sum total of the said olefin resin and the said acrylic resin is 10-75 mass%, It is characterized by the above-mentioned. Easy adhesive sheet.   The easy-adhesive sheet according to claim 1, further comprising a catalyst for the crosslinking agent.   The easily adhesive sheet according to claim 11, wherein the catalyst of the crosslinking agent is an onium compound.   The easily adhesive sheet according to claim 12, wherein the onium compound is at least one selected from the group consisting of an ammonium salt, a sulfonium salt, an iodonium salt, and a phosphonium salt.   The easily adhesive sheet according to claim 12, wherein the onium compound is dibasic ammonium phosphate.   The ratio of the catalyst of the said crosslinking agent with respect to the said crosslinking agent is 0.1 to 15 mass%, The easily adhesive sheet as described in any one of Claims 11-14 characterized by the above-mentioned. Wherein the olefin - easy adhesive sheet according to any one of claims 1 to 15 the content of the coloring pigment to acrylic composite polymer layer is characterized by a ^{2g / m 2 ~20g / m 2} .   The easily adhesive sheet according to any one of claims 1 to 16, wherein a volume fraction of the colored pigment with respect to the olefin-acrylic composite polymer layer is 15 to 40%.   The easy-adhesive sheet according to any one of claims 1 to 17, wherein the color pigment is titanium oxide or carbon black.   The easy-adhesive sheet according to any one of claims 1 to 18, wherein the color pigment is titanium oxide.   The easily adhesive sheet according to any one of claims 1 to 19, wherein the olefin-acrylic composite polymer layer has a thickness of 30 µm or less.   The easy adhesion sheet according to any one of claims 1 to 20, wherein the olefin-acrylic composite polymer layer is formed by coating.   The substrate film has a weather resistant layer containing at least one of a fluorine-based resin and a silicone-acrylic composite resin on a surface opposite to the surface on which the olefin-acrylic composite polymer layer is disposed. The easily adhesive sheet according to any one of claims 1 to 21. The easy-adhesive sheet according to any one of claims 1 to 22,
The insulating sheet, wherein the olefin-acrylic composite polymer layer is also disposed on a surface of the base film opposite to the surface on which the olefin-acrylic composite polymer layer is disposed. The easy-adhesive sheet according to any one of claims 1 to 22 or the insulating sheet according to claim 23,
The surface of the base film on the side where the olefin-acrylic composite polymer layer is disposed has a light reflectance at a wavelength of 550 nm of 70% or more, and the solar cell protective sheet.   A back sheet member for a solar cell, comprising the easy-adhesive sheet according to any one of claims 1 to 22, the insulating sheet according to claim 23, or the solar cell protective sheet according to claim 24. Or a solar cell backsheet. The solar cell backsheet member or solar cell backsheet according to claim 20,
A polymer layer that is directly bonded to at least the olefin-acrylic composite polymer layer side surface of the solar cell backsheet member or solar cell backsheet, and that includes an ethylene-vinyl acetate copolymer. A laminate for a solar cell characterized by the above. A transparent front substrate on the side where sunlight enters,
A solar cell element;
A sealing material for sealing the solar cell element;
A solar cell backsheet that is disposed on the side opposite to the front substrate of the sealing material and adheres to the sealing material;
The solar cell backsheet includes the solar cell backsheet member according to claim 25 or the solar cell backsheet. A transparent front substrate on the side where sunlight enters,
A solar cell element;
A sealing material for sealing the solar cell element;
A solar cell backsheet that is disposed on the side opposite to the front substrate of the sealing material and adheres to the sealing material;
A solar cell module comprising the solar cell laminate according to claim 26 as the solar cell backsheet and the sealing material.

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