JPWO2016009755A1 - Reflector for solar power generation - Google Patents

Abstract

An embodiment of the present invention is provided with a composite film having a water vapor transmission rate of 20 g / m 2 · day or less, a silver layer disposed on one surface of the composite film, and the silver layer on which sunlight enters. A solar power generation reflector having a glass substrate and a first adhesive layer disposed between the silver layer and the glass substrate is provided.

Description

  The present disclosure relates to a reflector for solar thermal power generation.

  In recent years, research on alternative energy alternatives to fossil fuels typified by oil, coal, natural gas, etc. has been conducted extensively. In particular, natural energy such as solar light, wind power, and geothermal heat has attracted attention as clean energy without concern about resource depletion and global warming. Among these, solar thermal power generation using solar energy is expected because stable power supply is possible.

On the other hand, solar energy has a problem of low energy density. In order to solve this problem, in recent years, attempts have been made to collect solar energy using a reflector for solar power generation.
Since solar power generation facilities are advantageous to be installed in places with a large amount of solar radiation, they are installed in areas with little rainfall, such as desert areas. Therefore, the reflector for solar power generation is used in harsh environments exposed to not only ultraviolet rays and heat caused by sunlight but also wind and rain, dust, etc., so it can withstand use in harsh environments. A reflector for solar power generation that is excellent in performance is required.
Furthermore, the surface of the solar power generation reflecting plate on which the sunlight is incident (hereinafter also simply referred to as “the surface of the solar power generation reflecting plate”) is contaminated and reflects sunlight (hereinafter referred to as “reflection performance”). May also be reduced. If the surface of the reflecting plate for solar power generation whose reflecting performance is deteriorated is washed with water or the like, it is possible to restore the reflecting ability inherent to the reflecting plate for solar power generation. The cleaning is often performed by an automatic cleaning device or the like. The surface on the solar light incident side of the solar power generation reflecting plate is required to have excellent scratch resistance, such that scratches and the like are hardly generated even by cleaning with an automatic cleaning device.

Japanese Patent Application Laid-Open No. 2013-231744 describes a film mirror for solar power generation having a silver reflective layer on a glass film having a thickness in the range of 1.0 μm to 200 μm.
In JP2012-251695A, a polymer layer containing a polymer film layer, a metal reflective layer such as a silver layer, and a corrosion inhibitor that prevents corrosion of the metal reflective layer in order from the side on which sunlight is incident. A film mirror is described. The film mirror described in JP2012-251695A is used by being attached to a substrate for maintaining its shape via an adhesive layer.

In the sunlight reflecting mirror described in JP2013-231744A, a resin material layer having a hollow structure is used as a self-supporting base material. Therefore, the solar reflective mirror described in JP2013-231744A is not sufficiently resistant to the weather resistance required for the solar power generation reflector, particularly the deterioration from the back surface of the solar power generation reflector.
Since the film mirror described in JP2012-251695A has a polymer film layer on the sunlight incident side, the weather resistance that can withstand use in harsh environments, and the maintenance that can withstand cleaning, etc. Insufficient sex.

  The embodiment of the present invention has been made in view of the above circumstances, and the problem of the embodiment of the present invention is to provide a reflector for solar power generation that is excellent in weather resistance and scratch resistance that can withstand washing and the like. is there.

Specific means for achieving the above object includes the following embodiments.
<1> A composite film having a water vapor transmission rate of 20 g / m ² · day or less, a silver layer disposed on one surface of the composite film, a glass base material provided on the silver layer and receiving sunlight, A solar power generation reflector having a first adhesive layer disposed between a silver layer and a glass substrate.

<2> The reflector for solar power generation according to <1>, wherein the composite film has, in order from the side close to the silver layer, a resin base material and at least one weathering layer formed on the resin base material.
<3> The composite film has a polyester film, a first weather resistant layer containing a silicone-acrylic composite resin, and a second weather resistant layer containing a fluororesin in order from the side closer to the silver layer <1> or The reflector for solar power generation as described in <2>.
<4> The solar power generation reflector according to <1>, wherein the composite film has a polyester film, a second adhesive layer, and an aluminum layer in order from the side closer to the silver layer.

<5> The solar power reflector according to <3> or <4>, wherein the polyester film is a biaxially stretched polyester film having a thickness of 150 μm or more and 500 μm or less.
<6> The composite film has a first adjacent layer containing a corrosion inhibitor that prevents silver corrosion as the outermost layer on the side having the silver layer, and the silver layer is disposed on the surface of the first adjacent layer. <1>-<5> The solar power generation reflecting plate as described in any one of.
<7> The method according to any one of <1> to <6>, further including a second adjacent layer containing a corrosion inhibitor that prevents silver corrosion between the silver layer and the first adhesive layer. Reflector for solar power generation.
The reflector for solar power generation as described in any one of <1>-<7> which has a surface coating layer further on the surface on the opposite side to the 1st adhesive bond layer side of <8> glass base material.

<9> The silver layer is a layer formed by applying a solution containing at least a silver compound represented by the following general formula A, an amine compound represented by the following general formula B, and water <1 The reflector for solar thermal power generation as described in any one of>-<8>.
Ag _n X: General formula A
R ¹¹ —CHR ¹² —CH ₂ —NH ₂ ... General Formula B
In general formula A, X is oxygen, sulfur, halogen, cyano, cyanate, carbonate, nitrate, nitrate, sulfate, phosphate, thiocyanate, chlorate, perchlorate, tetrafluoroborate, acetate, acetylacetonate, carboxylate, and these Represents a substituent selected from the derivatives of n represents an integer of 1 to 4.
In General Formula B, R ¹¹ and R ¹² each independently represent a hydrocarbon group having 1 to 12 carbon atoms.
<10> The solar power reflector according to <9>, wherein the silver compound is at least one selected from silver oxide, silver carbonate, silver nitrate, and silver acetate.
<11> The solar power generation reflector according to <9> or <10>, wherein the solution further contains a polar solvent other than water.
<12> The solar power generation reflector according to <11>, wherein the polar solvent other than water is an alcohol solvent or an amine solvent.
<13> The solution is a silver complex compound formed by the reaction of the amount of the silver compound represented by Formula A and the silver compound represented by Formula A and the amine compound represented by Formula B. The amount of the amine compound represented by the general formula B and the silver complex compound were converted to the amine compound represented by the general formula B with respect to 1 mol in total with the amount converted to the silver compound represented by the general formula A. The solar heat according to <11> or <12>, comprising a total amount of 2 mol to 30 mol, 3 mol to 100 mol of water, and 3 mol to 100 mol of a polar solvent other than water. Reflector for power generation.
The <14> solution is a reflector for solar power generation as described in any one of <9>-<13> which contains a reducing agent further.
The reflector for solar power generation as described in <14> whose <15> reducing agent is a compound represented by the following general formula C.
R-COOH: general formula C
In general formula C, R represents a hydrogen atom or a monovalent functional group having one or more aldehyde groups.

  According to the embodiment of the present invention, a reflector for solar power generation is provided that is excellent in weather resistance and scratch resistance that can withstand washing and the like.

It is sectional drawing of the reflector for solar power generation which concerns on 1st Embodiment of this invention. It is sectional drawing of the reflector for solar power generation which concerns on 2nd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail.
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.

(Reflector for solar thermal power generation)
A reflector for solar power generation according to one embodiment of the present invention is provided on a composite film having a water vapor transmission rate of 20 g / m ² · day or less, a silver layer disposed on one surface of the composite film, and the silver layer A glass substrate on which sunlight is incident, and a first adhesive layer disposed between the silver layer and the glass substrate.
In the reflector for solar power generation according to one embodiment of the present invention, the surface of the silver layer on the sunlight incident side is covered with a glass substrate, and the surface of the silver layer opposite to the sunlight incident side is water vapor. It is covered with a composite film having a transmittance of 20 g / m ² · day or less. Thereby, the reflector for solar power generation according to one embodiment of the present invention has scratch resistance that suppresses the generation of scratches associated with cleaning by an automatic cleaning machine or the like even in a harsh environment where the solar power generation apparatus is installed. In addition, the weather resistance is excellent.
In the sunlight reflecting mirror described in JP2013-231744A, a resin material layer having a hollow structure is used as a specific self-supporting base material, which is lightweight and flexible sunlight. It is described that a reflection mirror is obtained. However, a solar reflective mirror using a self-supporting base material including a resin material layer having a hollow structure is reflected by sunlight due to light irradiation, water intrusion, sand, etc. from the self-supporting base material side. The original reflection performance of the mirror is deteriorated.
In contrast, in the solar power generation reflector according to one embodiment of the present invention, the surface of the silver layer opposite to the sunlight incident side has a water vapor transmission rate of 20 g / m ² · day or less. Since it is covered with the composite film, it has excellent durability against the influence of water intrusion from the back surface of the solar power generation reflector. As a result, a reflector for solar power generation having excellent weather resistance can be obtained.
Furthermore, unlike the film mirror described in Japanese Patent Application Laid-Open No. 2012-251695, the reflector for solar power generation according to one embodiment of the present invention is provided with a glass substrate on the light incident side. Even if cleaning is performed with a machine or the like, the surface is less likely to be scratched and has excellent scratch resistance.

<Composite film>
The composite film according to one embodiment of the present invention has a water vapor transmission rate of 20 g / m ² · day or less. By providing the composite film, the effects of light irradiation, sand, and the like can be suppressed. Furthermore, since the water vapor transmission rate of the composite film is 20 g / m ² · day or less, the influence of water intrusion from the back surface of the solar power generation reflector is reduced, and the solar power generation reflector excellent in weather resistance is obtained. can get.
The water vapor transmission rate of the composite film is preferably 18 g / m ² · day or less, because a solar power generation reflector having further excellent durability is obtained, and more preferably 15 g / m ² · day or less. preferable. Specific examples of the water vapor transmission rate include values of 4 g / m ² · day, 2 g / m ² · day, and 0.5 g / m ² · day.
The water vapor transmission rate is a value measured by a method according to JIS K7129 (2008) “Plastics-films and sheets—How to obtain water vapor transmission rate (instrument measurement method)”.

A composite film having a water vapor transmission rate of 20 g / m ² · day or less according to an embodiment of the present invention includes a resin base material and a weather resistant layer functioning as at least one water vapor barrier layer formed on the resin base material. It is preferable to have.
In one embodiment of the invention, particularly preferred composite films include
(1) A composite film A having a polyester film, a first weathering layer containing a silicone-acrylic composite resin, and a second weathering layer containing a fluororesin, and (2) a polyester film and a second adhesive A composite film B having a layer and an aluminum layer;
Is included.
In the composite film A, the first weathering layer containing the silicone-acrylic composite resin functions as a water vapor barrier layer, and hydrolysis resistance and weather resistance are imparted by the second weathering layer containing the fluororesin. Yes.
In the composite film B, the aluminum layer functions as a water vapor barrier layer, and also has a function of imparting hydrolysis resistance and weather resistance.

  Hereinafter, the reflector for solar power generation provided with the composite film A or B will be described in detail with reference to the drawings as appropriate, but the present invention is not limited to the following embodiments at all. Within the range of the objective, it can implement by changing suitably. In the figure, members having the same or corresponding functions are denoted by the same reference numerals, and description thereof is omitted as appropriate. The size and shape of each part are appropriately exaggerated for easy understanding.

-Composite film A-
FIG. 1 is a cross-sectional view of a solar power generation reflector according to a first embodiment of the present invention using the composite film A as the composite film 20.
In FIG. 1, the solar power generation reflector includes a composite film 20, a silver layer 14 disposed on the surface of the composite film 20, an adhesive layer 32, and a glass substrate 12.
The composite film 20 is a composite film A having a polyester film 22, a first weathering layer 24 containing a silicone-acrylic composite resin, and a second weathering layer 26 containing a fluororesin.

<Polyester film>
The polyester film 22 is preferably a biaxially stretched polyester film, and more preferably a hydrolysis-resistant biaxially stretched polyester film.
Examples of the hydrolysis-resistant biaxially stretched polyester film include those described in JP2011-208125A.

  The thickness of the polyester film 22 included in the composite film 20 is preferably in the range of 150 μm or more and 500 μm or less because a reflector for solar power generation having excellent bending resistance can be obtained. A more preferable thickness is 150 μm or more and 350 μm or less, and a more preferable range is 200 μm or more and 300 μm or less.

The surface of the polyester film 22 may further have an easy adhesion layer. The easy-adhesion layer may be formed by, for example, applying and drying a composition containing a water-dispersed latex as a binder component. And it is preferable that the silver layer 14 is provided in the surface of the easily bonding layer of the polyester film 22. FIG. Since the silver layer is in contact with the surface of the easy adhesion layer, the adhesion of the silver layer can be further improved.
The thickness of the easy adhesion layer is preferably 0.05 μm to 10 μm in terms of adhesion.

  Polyester films having an easy-adhesion layer are commercially available, for example, Cosmo Shine (registered trademark) A-4100 (polyethylene terephthalate film), Cosmo Shine (registered trademark) A-4300 (polyethylene terephthalate film) manufactured by Toyobo Co., Ltd. Can be mentioned.

<First weathering layer>
The first weather resistant layer 24 includes a silicone-acrylic composite resin.
[Silicone-acrylic composite resin]
The silicone-acrylic composite resin has a repeating unit (hereinafter also referred to as “polysiloxane structure”) composed of a siloxane bond in a polymer chain and a repeating unit obtained by polymerizing an acrylic monomer (hereinafter referred to as “acrylic polymer”). And also a “structure”). Here, the “acrylic monomer” includes a methacrylic monomer.
The siloxane bond is preferably represented by the following general formula 1.
—Si (R ¹ ) (R ² ) —O— General Formula 1
In General Formula 1, R ¹ and R ² independently represent a monovalent organic group that can be covalently bonded to a Si atom.

Examples of the “monovalent organic group that can be covalently bonded to the Si atom” represented by R ¹ and R ² include, for example, 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.), 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.).
R ¹ and R ² are 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, or an unsubstituted group. Of these, an amino group and an amide group are preferable.

  Specific examples of polysiloxane structures include: dimethyldimethoxysilane; a mixture of dimethyldimethoxysilane and γ-methacryloyloxytrimethoxysilane; a mixture of dimethyldimethoxysilane and vinyltrimethoxysilane; dimethyldimethoxysilane and 2-hydroxyethyltrimethoxysilane. Mixture; Mixture of dimethyldimethoxysilane and 3-glycidoxypropyltriethoxysilane; Structure obtained by hydrolysis and condensation of a mixture of dimethyldimethoxysilane, diphenyldimethoxysilane and γ-methacryloyloxytrimethoxysilane .

The polysiloxane structure in the silicone-acrylic composite resin may be a linear structure or a branched structure. Furthermore, a part of the polysiloxane structure may form a ring.
The content ratio of the siloxane structure in the silicone-acrylic composite resin is preferably in the range of 15% by mass to 85% by mass with respect to the total mass of the silicone-acrylic composite resin, and more preferably in the range of 20% by mass to 80% by mass. A range is particularly preferred.
When the content ratio of the polysiloxane structure is 15% by mass or more, a reflector for solar power generation with excellent weather resistance, in particular, a decrease in adhesive strength with the polyester film 22 is obtained. On the other hand, when the content ratio of the polysiloxane structure is 85% by mass or less, the production of the reflector for solar power generation becomes easy.
The molecular weight of the polysiloxane structure in the silicone-acrylic composite resin is about 30,000 to 1,000,000 in terms of polystyrene-converted weight average molecular weight, and more preferably about 50,000 to 300,000.

The silicone-acrylic composite resin includes a polysiloxane structure and an acrylic polymer structure that is a repeating unit obtained by polymerizing an acrylic monomer.
As acrylic monomers, esters of acrylic acid (eg, ethyl acrylate, butyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, etc.), esters of methacrylic acid (eg: methyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, glycidyl methacrylate, dimethyl) Aminoethyl methacrylate, etc.), unsaturated carboxylic acids such as acrylic acid, methacrylic acid and itaconic acid, and acrylamide.
The acrylic polymer structure is preferably obtained by polymerizing at least one of the acrylic monomers.
Specific examples of the combination of monomers when polymerizing two or more kinds of acrylic monomers include a combination of methyl methacrylate, ethyl acrylate and acrylic acid; a combination of methyl methacrylate, ethyl acrylate, 2-bidoxyethyl methacrylate and methacrylic acid; Examples include combinations of methyl methacrylate, butyl acrylate, 2-bidoxyethyl methacrylate, methacrylic acid and γ-methacryloyloxytrimethoxysilane; combinations of methyl methacrylate, ethyl acrylate, glycidyl methacrylate and acrylic acid.

  The molecular weight of the acrylic polymer structure in the silicone-acrylic composite resin is preferably in the range of 3,000 to 1,000,000, more preferably in the range of 5,000 to 300,000, in terms of polystyrene-converted weight average molecular weight.

The silicone-acrylic composite resin can be synthesized using a known synthesis method.
For example, the following synthesis methods 1-3 are mentioned.
Synthesis method 1: A synthesis method in which a polymer constituting a polysiloxane structure and a polymer constituting an acrylic polymer structure are separately synthesized in advance, and both polymers are chemically bonded.
Synthesis method 2: A synthesis method in which a polymer constituting a polysiloxane structure is synthesized in advance, and a repeating unit constituting an acrylic polymer structure is graft-polymerized on the synthesized polymer constituting the polysiloxane structure.
Synthesis method 3: A synthesis method in which a polymer constituting an acrylic polymer structure is polymerized in advance, and a polymer constituting a polysiloxane structure is graft-polymerized on the synthesized polymer constituting the acrylic polymer structure.
The synthesis methods 2 and 3 are preferable because they are easy synthesis methods.

As a specific example of the synthesis method 2, for example, γ-methacryloyloxytrimethylsilane or the like is hydrolyzed and condensed to synthesize a polymer having a polysiloxane structure. Examples include a method of synthesizing a silicone-acrylic composite resin by radical polymerization of a methacryloyl group of a polymer having a synthesized polysiloxane structure and an acrylic monomer constituting an acrylic polymer structure.
In addition, as another synthesis method for copolymerizing polysiloxane with an acrylic polymer constituting an acrylic polymer structure, hydrolysis and polycondensation are performed by adding an alkoxysilane compound to an aqueous dispersion of the above acrylic polymer containing γ-methacryloyloxytrimethylsilane. And a method of synthesizing a silicone-acrylic composite resin.

For the acrylic polymer structure copolymerized with the polysiloxane moiety, known polymerization methods such as emulsion polymerization and bulk polymerization can be used, but emulsion polymerization is particularly preferred from the viewpoint of ease of synthesis and obtaining an aqueous polymer dispersion. .
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.

  The silicone-acrylic composite resin is preferably used in the form of an aqueous polymer dispersion (so-called latex). The preferable average particle diameter (diameter) of the latex of the silicone-acrylic composite resin is 50 nm to 500 nm, and the preferable concentration with respect to the total mass of the latex is 15 mass% to 50 mass%. The average particle size of the latex is determined by a commercially available particle size measuring device.

The silicone-acrylic composite resin 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-acrylic composite resin 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-acrylic composite resins are commercially available. Specific examples of commercially available products include, for example, Ceranate (registered trademark) WSA1060, 1070 (manufactured by DIC Corporation), Polydurex (registered trademark) H7620, H7630, H7650 (manufactured by Asahi Kasei Chemicals Corporation), and the like. .

It is preferable to crosslink the silicone-acrylic composite resin contained in the first weathering layer 24 with a crosslinking agent, since a reflector for solar power generation having excellent weather resistance can be obtained.
[Crosslinking agent]
Examples of the crosslinking agent include epoxy-based, isocyanate-based, melamine-based, carbodiimide-based, and oxazoline-based crosslinking agents. From the viewpoint of ensuring adhesion with the polyester film 22 after wet heat, a crosslinking agent selected from a carbodiimide crosslinking agent, an oxazoline crosslinking agent, an isocyanate crosslinking agent, and an epoxy crosslinking agent is preferable, and in particular, an oxazoline crosslinking agent. (Compound having an oxazoline group) is preferred.

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′-tetra Methylene-bis (2-oxazoline), 2,2′-hexamethylene-bis (2-oxazoline), 2,2′-octamethylene-bis (2-oxazoline), 2,2′-ethylenebis (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-oxazoline) Nylcyclohexane) sulfide, bis (2-oxazolinylnorbornane) 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 includes a repeating unit formed by addition polymerization of an addition-polymerizable oxazoline. The polymer oxazoline-based crosslinking agent also includes a copolymer obtained by polymerizing an addition polymerizable oxazoline and a monomer copolymerizable with the addition polymerizable oxazoline.
Examples of addition polymerizable oxazolines include 2-vinyl-2-oxazoline, 2-vinyl-4methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-iso Propenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, and the like are preferred, and these may be used alone or in combination of two or more. May be used. Among these, 2-isopropenyl-2-oxazoline is preferable for easy availability and good adhesion. The use amount of these addition polymerizable oxazolines is not particularly limited, but is preferably 5% by mass or more in the monomer component, more preferably 5% by mass to 90% by mass, and further preferably 10% by mass to 60% by mass, 30 mass%-60 mass% is especially preferable.
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, Caprolac 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, vinylidene chloride and fluoride Α, β-unsaturated aliphatic hydrocarbons containing halogen such as vinyl; α, β-unsaturated aromatic hydrocarbons such as styrene, α-methylstyrene and sodium styrenesulfonate, etc. Two or more types may be used in combination.
The oxazoline-based crosslinking agent, that is, a copolymer containing a repeating unit formed by polymerizing a (meth) acrylic acid ester is preferable.

The oxazoline-based crosslinking agent is preferably water-soluble 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. Here, “water-soluble” means that it can be dissolved in water at a certain concentration or more (specifically, at least 50% by mass).
The polymerization method for preparing 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. In order to improve the adhesion and weather resistance, the polymer oxazoline-based cross-linking agent is, for example, an emulsifier, a compound having a protective colloid action, a modified wax, and a high acid value acid-modified compound. It is preferable that the agent is not substantially contained.

  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.

  The oxazoline-based crosslinking agent may be a commercially available product. For example, an aqueous dispersion type Epocross (registered trademark) “K-1010E”, “K-1020E”, “K-1030E”, K2010E, K2020E, K2030E, an aqueous solution type WS500, WS700 [Epocross (registered trademark) series made by Nippon Shokubai Co., Ltd.], etc. can be used.

  The content of the crosslinking agent with respect to the total mass of the composition for forming the first weathering layer 24 is preferably 10% by mass to 75% by mass, and more preferably 15% by mass to 60% by mass. A range of 20% by mass to 50% by mass is particularly preferable. When the content of the cross-linking agent is 10% by mass or more, a sufficient cross-linking effect is obtained, and a decrease in strength of the polymer layer and poor adhesion can be suppressed. On the other hand, the pot life fall of said composition can be prevented because it is 75 mass% or less.

[Catalyst for cross-linking agent]
In order to promote the cross-linking reaction by the cross-linking agent, it is preferable to contain at least one cross-linking agent catalyst together with the cross-linking agent. By using the catalyst for the crosslinking agent in combination, the crosslinking reaction with the silicone-acrylic composite resin is promoted, the weather resistance is improved, and the adhesion with the polyester film 22 is also improved.
In particular, when an oxazoline-based crosslinking agent is included as a crosslinking agent, it is preferable to further include a crosslinking agent catalyst.

Examples of the crosslinking agent catalyst 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 ammonium salts include monoammonium phosphate, diammonium phosphate, ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium p-toluenesulfonate, ammonium sulfamate, ammonium imidodisulfonate, tetrabutylammonium chloride, benzyltrimethylammonium chloride. Triethylbenzylammonium chloride, tetrabutylammonium tetrafluoride, tetrabutylammonium hexafluoride, tetrabutylammonium perchlorate, tetrabutylammonium sulfate, and the like.
Specific examples of the sulfonium salt include trimethylsulfonium iodide, boron trifluoride trimethylsulfonium, boron tetrafluoride diphenylmethylsulfonium, boron tetrafluoride benzyltetramethylenesulfonium, antimony hexafluoride 2-butenyltetramethylenesulfonium, six And antimony fluoride 3-methyl-2-butenyltetramethylenesulfonium.
Specific examples of the oxonium salt include oxonium salts such as boron trifluoride trimethyloxonium.
Specific examples of the iodonium salt include diphenyliodonium chloride and boron tetrafluoride diphenyliodonium.
Specific examples of the phosphonium salt include antimony antimony cyanomethyl tributyl phosphonium, boron tetrafluoride ethoxycarbonylmethyl tributyl phosphonium, and the like.
Specific examples of the nitronium salt include nitronium boron tetrafluoride and the like.
Specific examples of the nitrosonium salt include boron tetrafluoride nitrosonium and the like.
Specific examples of the diazonium salt include 4-methoxybenzenediazonium chloride.

  Among the above onium compounds, ammonium salts, sulfonium salts, iodonium salts, and phosphonium salts are more preferable in terms of shortening the curing time, and among these, ammonium salts are more preferable, from the viewpoints of safety, pH, and cost. Is preferably phosphoric acid or benzyl chloride. More preferably, the onium compound is dibasic ammonium phosphate.

The catalyst for the crosslinking agent may be only one type, or two or more types may be used in combination.
The content of the catalyst of the crosslinking agent is preferably in the range of 0.1% by mass or more and 15% by mass or less, more preferably in the range of 0.5% by mass or more and 12% by mass or less, based on the mass of the crosslinking agent. % To 10% by mass is particularly preferable, and 2% to 7% by mass is more preferable. That the content of the crosslinking agent catalyst with respect to the crosslinking agent is 0.1% by mass or more means that the crosslinking agent catalyst is actively contained, and the polymer is crosslinked by the inclusion of the crosslinking agent catalyst. The cross-linking reaction between the agents 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 a crosslinking agent is 15 mass% or less.

  The thickness of the first weathering layer 24 is preferably 0.5 μm or more and 15 μm or less, and more preferably 3 μm to 10 μm. By setting the thickness to 0.5 μm or more, a reflector for solar power generation having excellent weather resistance and bending resistance can be obtained.

<Second weathering layer>
The second weather resistant layer 26 includes a fluororesin.
[Fluororesin]
As the fluororesin contained in the second weather resistant layer 26, a polymer having a repeating unit represented by the following general formula 2 is preferable.
^{- (CFX 1 -CX 2 X 3} ) - ··· general formula 2
In General Formula 2, X ¹ , X ² , and X ³ each independently represent a hydrogen atom, a fluorine atom, a chlorine atom, or a perfluoroalkyl group having 1 to 3 carbon atoms.
Specific examples of the fluororesin include polytetrafluoroethylene (hereinafter sometimes referred to as PTFE), polyvinyl fluoride (hereinafter sometimes referred to as PVF), and polyvinylidene fluoride (hereinafter sometimes referred to as PVDF). And polychlorinated ethylene trifluoride (hereinafter sometimes referred to as PCTFE), polytetrafluoropropylene (hereinafter sometimes referred to as HFP), and the like.

The fluororesin may be a homopolymer obtained by polymerizing a single monomer or a copolymer obtained by copolymerizing two or more kinds. Specific examples of the copolymer include a copolymer obtained by copolymerizing tetrafluoroethylene and tetrafluoropropylene (abbreviated as P (TFE / HFP)), and a copolymer obtained by copolymerizing tetrafluoroethylene and vinylidene fluoride (abbreviated as P (TFE / VDF)). And the like.
Further, the fluororesin may be a polymer containing a fluorine-based structural unit composed of the repeating unit represented by the general formula 2 and a structural unit composed of other repeating units. Specifically, a copolymer of tetrafluoroethylene and ethylene (hereinafter abbreviated as P (TFE / E)), a copolymer of tetrafluoroethylene and propylene (abbreviated as P (TFE / P)), tetrafluoroethylene. Copolymer of vinyl ether (abbreviated as P (TFE / VE)), copolymer of tetrafluoroethylene and perfluorovinyl ether (abbreviated as P (TFE / FVE)), copolymer of chlorotrifluoroethylene and vinyl ether ( P (CTFE / VE)), a copolymer of chlorotrifluoroethylene and perfluorovinyl ether (abbreviated as P (CTFE / FVE)), and the like.
Among them, the fluororesin contained in the second weather resistant layer 26 is particularly preferably a fluororesin containing a repeating unit formed by polymerizing chlorotrifluoroethylene from the viewpoint of ease of production and excellent weather resistance. .

The fluororesin contained in the second weather resistant layer 26 may be used by being dissolved in an organic solvent, or may be used as an aqueous dispersion dispersed in water in the form of fine particles. The latter is preferred because of its low environmental impact. The aqueous dispersion of fluororesin is described in, for example, Japanese Patent Application Laid-Open Nos. 2003-231722, 2002-20409, and 9-194538.
A commercial item can also be used as a fluororesin. For example, Obligato (registered trademark) SW0011F (manufactured by AGC Co-Tech), Lumiflon (registered trademark) LF200 (manufactured by Asahi Glass Co., Ltd.), Zeffle (registered trademark) GK570 (manufactured by Daikin Industries, Ltd., SIFCLEAR F101, F102 ( JSR Co., Ltd.)) and the like.

The second weather resistant layer 26 includes the aforementioned fluororesin. The second weather resistant layer 26 may contain one type of fluororesin alone or in combination of two or more types. The second weathering layer 26 may contain a resin other than the fluororesin such as an acrylic resin, a polyester resin, a polyurethane resin, a polyolefin resin, and a silicone resin within a range not exceeding 50 mass% with respect to the mass of the fluororesin. Good.
In the second weathering layer 26, it is preferable to crosslink the fluororesin with a cross-linking agent because a solar power generation reflector having excellent weather resistance can be obtained. In the case of crosslinking with a crosslinking agent, it is preferable to use a catalyst for the crosslinking agent in combination. The crosslinking agent used for the second weathering layer 26 and the catalyst for the crosslinking agent can be the crosslinking agent used for the first weathering layer and the catalyst for the crosslinking agent. Further, the amount of the crosslinking agent used in the second weathering layer 26 and the catalyst of the crosslinking agent are the same as in the case of the first weathering layer.

The second weathering layer 26 preferably contains a lubricant.
[Lubricant]
The second weather-resistant layer 26 preferably contains a lubricant in order to suppress a decrease in slipperiness (that is, an increase in the dynamic friction coefficient) that is likely to occur because it contains a fluororesin.
As a preferable lubricant, an olefin-based lubricant (high softening point olefin-based lubricant) having a ring and ball softening point of 120 ° C. or higher and 200 ° C. or lower is preferable. Here, the ring-and-ball softening point is a value measured by the ring-and-ball method in accordance with JIS K2207. Specifically, the ring-and-ball softening point is a value measured by a ring and ball automatic softening point tester ASP-MG2 manufactured by Meitec. is there.

  When the second weather-resistant layer 26 is the outermost layer, the susceptibility to scratches caused by external forces such as scratches, scratches, and collisions with pebbles is dramatically reduced. Moreover, it is possible to prevent the occurrence of pinhole-like defects in the coating layer that is likely to occur when a fluororesin is used, and it is possible to form the second weather resistant layer 26 having a good surface shape.

  The high softening point olefin-based lubricant preferably contains at least one of an ethylene unit and a propylene unit. Examples thereof include polyolefin waxes such as polyethylene wax and polypropylene wax having a ring and ball softening point of 120 ° C. or higher and 200 ° C. or lower.

  The high softening point olefin-based lubricant preferably contains an acid-modified olefin resin as the olefin resin. Examples of the high softening point olefin-based lubricant containing an acid-modified olefin resin include Chemipearl (registered trademark) series (for example, Chemipearl (registered trademark) W300, W700, W900, WP100, etc.) manufactured by Mitsui Chemicals, Ltd., high wax ( (Registered trademark) series (for example, high wax (registered trademark) NP50605A, NP0555A) and the like.

  The size of the high softening point olefin-based lubricant is preferably 2 μm or less, more preferably 1 μm or less, from the viewpoint of scratch resistance. The median diameter of the high softening point olefin-based lubricant is a value measured by a laser analysis / scattering particle size distribution measuring device MT3300EX2 [manufactured by Nikkiso Co., Ltd.].

  The ring and ball softening point of the high softening point olefin-based lubricant contained in the second weathering layer 26 is preferably 130 ° C. or higher from the viewpoint of preventing melting in the drying step.

  From the viewpoint of scratch resistance, the number average molecular weight (Mn) of the olefin resin contained in the high softening point olefin-based lubricant is preferably 3000 or more and 10,000 or less, and more preferably 3000 or more and 8000 or less. The number average molecular weight (Mn) of the olefin resin contained in the high softening point olefin-based lubricant is the number average molecular weight in terms of polystyrene measured by gel permeation chromatography and is measured by a molecular weight distribution measurement system manufactured by Shimadzu Corporation. Value.

  A commercially available high softening point olefin-based lubricant may be used. Chemipearl (registered trademark) series (for example, Chemipearl (registered trademark) W300, W700, W900, WP100, etc.) manufactured by Mitsui Chemicals, Inc., high wax (registered trademark) series (for example, high wax (registered trademark) NP50605A, NP0555A) And Polylon P-502, Hydrin L-536 (all trade names) manufactured by Chukyo Yushi Co., Ltd., and the like.

  The content of the high softening point olefin-based lubricant in the second weather resistant layer 26 is preferably 4 to 30 parts by mass of the high softening point olefin-based lubricant with respect to 100 parts by mass of the fluororesin. More preferably, the content is 15 parts by mass or more. If 4 parts by mass or more of the high softening point olefin-based lubricant is included with respect to 100 parts by mass of the fluororesin, the effect of reducing the dynamic friction coefficient by containing the lubricant is surely obtained. In this case, it is less likely that coating unevenness or aggregates are generated, or that no pinhole-like polymer layer is formed.

  From the viewpoint of weather resistance and film strength, the content of the fluororesin relative to the total mass of the components contained in the second weathering layer 26 is preferably 40% by mass or more and 90% by mass or less, and 50% by mass or more and 80% by mass. % Or less is more preferable.

  The thickness of the second weather resistant layer 26 is preferably in the range of 0.1 μm to 5 μm from the viewpoint of weather resistance and film strength, more preferably 0.5 μm to 3 μm, and more preferably 0.8 μm to 3 μm. More preferably, it is as follows.

[Inorganic particles]
At least one of the first weather resistant layer 24 and the second weather resistant layer 26 may contain inorganic particles. An embodiment in which the first weathering layer 24 contains inorganic particles is more preferable.
Inorganic particles include light reflecting titanium oxide, barium sulfate, silicon oxide, aluminum oxide, magnesium oxide, calcium carbonate, kaolin, talc, colloidal silica, etc., carbon black, titanium black, and black composites A metal oxide etc. are mentioned.
Here, as the black composite metal oxide, a composite metal oxide containing at least one of iron, manganese, cobalt, chromium, copper, and nickel is preferable, and among cobalt, chromium, iron, manganese, copper, and nickel It is more preferable to include at least two types, and at least one pigment selected from PBk26, PBk27, PBk28, and PBr34 is more particularly preferable.
The PBk26 pigment is a complex oxide of iron, manganese and copper, the PBk-27 pigment is a complex oxide of iron, cobalt and chromium, and the PBk-28 is a complex oxide of copper, chromium and manganese. PBr34 is a composite oxide of nickel and iron.

The volume average particle size of the inorganic particles 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 inorganic particles in the above range, it is possible to suppress a decrease in light reflection efficiency.
The volume average particle diameter of the inorganic particles is a value (solvent: water, particle shape: non-spherical, particle refractive index: 2.7, ultrasonic treatment: none) measured by Nikkiso Co., Ltd., Microtrac MT3300EX2. .

  A reflector for solar power generation that contains inorganic particles having light reflectivity excellent in performance of reflecting sunlight in the first weather-resistant layer 24 is preferable because it can efficiently use solar energy. In a solar power generation facility, a large number of solar power generation reflectors are arranged side by side on the ground. When attention is paid to the two solar power generation reflectors installed before and after the sun, the sunlight reflected by the solar power generation reflector installed later with respect to the sun is reflected in the solar heat installed in front. It is reflected again by the first weathering layer 24 of the power generation reflector. The sunlight reflected again by the first weathering layer 24 is reflected again by the mirror surface of the solar power generation reflector installed behind and collected in the heat collecting device, so that the utilization efficiency of solar energy is improved. Because.

Specific examples of the inorganic particles having light reflectivity are as described above. Of these, titanium oxide is preferable.
The crystal system of titanium oxide includes a rutile type, anatase type, and brookite type, and a rutile type is preferred. Titanium oxide may be surface-treated with aluminum oxide (Al ₂ O ₃ ), silicon dioxide (SiO ₂ ), alkanolamine compound, silicon compound or the like as necessary.
In particular, by using titanium oxide having a bulk specific gravity of 0.50 g / cm ³ or more and 0.85 g / cm ³ or less, titanium oxide is densely packed, and the first weathering layer 24 becomes tough. On the other hand, when a titanium oxide having a bulk specific gravity exceeding 0.85 g / cm ³ is used, the dispersibility of the titanium oxide is deteriorated and the surface state of the coating layer is deteriorated. By making the bulk specific gravity 0.50 g / cm ³ or more and 0.85 g / cm ³ or less, the titanium oxide is densely packed and the coating film becomes tough, so that even if the mass ratio of the titanium oxide is set high, the adhesion Sex can be maintained high. The bulk specific gravity of titanium oxide used for the first weathering layer 24 is particularly preferably 0.60 g / cm ³ or more and 0.80 g / cm ³ or less.

The bulk specific gravity in this specification is a value measured by the following method.
(1) The pigment is passed through a sieve having an aperture of 1.0 mm.
(2) About the above-mentioned pigment, about 100 g of pigment is weighed (m) and gently put into a 250 mL graduated cylinder. If necessary, the top surface of the pigment layer is carefully leveled without compaction and the volume (V) is measured.
(3) The bulk specific gravity is obtained according to the following formula.
Bulk specific gravity = m / V (unit: g / cm ³ )

The solar power generation reflector including the light-reflective inorganic particles in the first weather-resistant layer 24 has the image clarity measured by being incident on the silver layer 14 from the side of the composite film 20, and the following conditions 1 and 2 are satisfied. Satisfaction is preferable because it is excellent in utilization efficiency of solar energy.
Condition 1: The image clarity when the incident angle is 45 degrees and the optical comb width is 2 mm is 15% or more.
Condition 2: The image clarity is 20% or more when the incident angle is 60 degrees and the optical comb width is 2 mm.
Here, “image clarity” is the sum of both when the maximum light amount in light passing through an optical comb having the same width (comb width) of the light transmitting portion and the light non-transmitting portion is M and the minimum light amount is m. It is the value which expressed the ratio of both difference (M-m) with respect to (M + m) in percentage.

  As the other components, the first weathering layer 24 and the second weathering layer 26 include surfactants, matting agents such as colloidal silica, silane coupling agents that improve adhesion, ultraviolet absorbers, and antioxidants. An agent or the like may be included.

-Composite film B-
FIG. 2 is a cross-sectional view of a solar power generation reflector according to the second embodiment of the present invention using the above-described composite film B as the composite film 20.
In FIG. 2, the composite film 20 has the same configuration as that of the reflector for solar power generation according to the first embodiment of the present invention, except that the composite film B is included. That is, in FIG. 2, the composite film 20 is a composite film B having a polyester film 22, a second adhesive layer 34, and an aluminum layer 28.

  As the polyester film 22 in the composite film B, the same polyester film as the composite film A described above can be used, a biaxially stretched polyester film is preferable, and a hydrolysis-resistant biaxially stretched polyester film is more preferable.

The second adhesive layer 34 in the composite film B has a function of joining the polyester film 22 and the aluminum layer 28 and is preferably a composition containing a crosslinking agent and a binder resin.
Examples of the crosslinking agent include divinylbenzene.
As the binder resin, polyolefin resin, polyester resin, acrylic resin, and polyurethane resin are preferable from the viewpoint of adhesiveness.

  Polyolefin resins include polyethylene resins, polypropylene resins, ethylene-propylene copolymer resins, resins obtained by polymerizing at least one diene monomer such as butadiene, isoprene, and chloroprene, and copolymers of the above diene monomers with styrene. Examples of the resin include a polyene structure such as a resin obtained by copolymerizing a possible comonomer.

<Aluminum layer>
The aluminum layer 28 in the composite film B includes an aluminum thin film formed by vacuum deposition of aluminum by vapor deposition or sputtering, and an aluminum foil.
The thickness of the aluminum thin film obtained by vacuum forming aluminum is preferably 10 nm or more and 300 nm or less because a composite film having a low water vapor transmission rate can be obtained.
The thickness of the aluminum foil is preferably 1 μm or more and 30 μm or less because a composite film having a low water vapor transmission rate can be obtained.

  In addition, the composite film 20 is formed by attaching a weather resistant layer having a thickness of, for example, 50 μm to a polyester film having a thickness of 100 μm or more and 500 μm or less via an adhesive layer. It may be combined.

Hereinafter, the preferable aspect of the reflector for solar power generation shown in FIG.1 and FIG.2 is demonstrated.
-First adjacent layer-
The composite film 20 may have a first adjacent layer (not shown) formed by coating on the side having the silver layer 14 as the outermost layer. By providing a 1st adjacent layer, the adhesiveness between a base material and a specific silver layer improves more.
Furthermore, it is preferable to contain a corrosion inhibitor for preventing silver corrosion in the first adjacent layer because a reflector for solar power generation having superior weather resistance can be obtained.

(Corrosion inhibitor to prevent silver corrosion)
Corrosion inhibitors that prevent silver corrosion have the function of preventing discoloration of the silver layer, such as thioether compounds, thiol compounds, Ni organic compounds, benzotriazole compounds, imidazole compounds, oxazole compounds, tetrazaindene compounds, pyrimidine compounds And thiadiazole compounds.
The content of the above-mentioned corrosion inhibitor in the first adjacent layer is in the range of 0.001% by mass to 20% by mass with respect to the total mass of the first adjacent layer to prevent corrosion of the silver layer. This is preferable because of its excellent effect.

  When the composite film is composed of the composite film A or the composite film B described above, the first adjacent layer may be provided as an undercoat layer of the polyester film 22, for example. The first adjacent layer may have a single layer configuration or a plurality of layers of two or more layers. When the first adjacent layer is a plurality of layers of two or more layers, the corrosion inhibitor for preventing silver corrosion is preferably contained in the outermost layer close to the silver layer 14.

  The first adjacent layer may be formed using a compound having a polymerizable double bond (for example, an acrylate compound or a methacrylate compound) in order to promote cross-linking in the layer. In particular, it is preferable to use a polyfunctional compound. Examples of the compound having a polymerizable double bond also include a thermosetting resin or a thermoplastic resin, and specific examples include an epoxy resin, a phenol resin, a polyimide resin, a polyolefin resin, a fluorine resin, A resin obtained by partially methacrylic acid using methacrylic acid or acrylic acid may be used.

  If necessary, the first adjacent layer may contain one or more various additives such as an adhesion promoter, a silane coupling agent, an antioxidant, a surfactant, and an ultraviolet absorber. .

  In general, the thickness of the first adjacent layer is preferably in the range of 0.05 μm to 10 μm, and more preferably in the range of 0.1 μm to 5 μm in terms of adhesion.

<Silver layer>
The silver layer 14 is disposed on the surface of the composite film 20.
The silver layer 14 has a function of reflecting sunlight, and is preferably a silver layer made of silver or an alloy containing silver.
As the silver alloy, silver and one or more metals selected from the group consisting of gold, palladium, tin, gallium, indium, copper, titanium, and bismuth are used in that the durability of the silver layer is improved. An alloy is preferred. As the silver alloy, an alloy of silver and gold is particularly preferable from the viewpoints of heat and humidity resistance, reflectance, and the like.

  The silver content in the silver layer 14 is preferably 90 atomic% to 99.8 atomic% in the metal (100 atomic%) contained in the silver layer 14. Moreover, it is preferable that content of another metal is 0.2 atomic%-10 atomic% from a durable point. The silver content is determined by a silver meter.

The thickness of the silver layer 14 is preferably in the range of 0.5 g / m ² or more and 2.0 g / m ² or less, particularly 0.7 g / m ² or more from the viewpoint that high reflectance is obtained and durability is excellent. A range of 1.2 g / m ² or less is more preferable.

  The surface roughness (Ra) on the sunlight incidence side of the silver layer is preferably 20 nm or less, more preferably 10 nm or less, and still more preferably 5 nm or less. When the surface roughness (Ra) of the silver layer is within the above range, the reflectance as a solar power generation reflector is improved, so that sunlight can be efficiently collected. Here, the surface roughness (Ra) is an arithmetic average roughness obtained in accordance with JIS B0601 (1994).

[Method of forming silver layer]
The silver layer 14 can be formed by either a wet method or a dry method. Examples of the wet method include an electroplating method, an electroless plating method, a silver complex coating firing method, and the like. Examples of the dry method include a vacuum deposition method, a sputtering method, and an ion plating method.

The silver layer 14 is also referred to as a solution containing a silver compound represented by the following general formula A, an amine compound represented by the following general formula B, and water (hereinafter also referred to as “specific silver layer forming coating solution”). ) Is preferably a silver layer (hereinafter, also referred to as “specific silver layer”), because the production burden is small and the reflection performance as a reflector for solar thermal power generation is excellent.
Ag _n X: General formula A
In general formula A, X is oxygen, sulfur, halogen, cyano, cyanate, carbonate, nitrate, nitrate, sulfate, phosphate, thiocyanate, chlorate, perchlorate, tetrafluoroborate, acetate, acetylacetonate, carboxylate, and these Represents a substituent selected from the derivatives of
n represents an integer of 1 to 4.
R ¹¹ —CHR ¹² —CH ₂ —NH ₂ ... General Formula B
In General Formula B, R ¹¹ and R ¹² each independently represent a hydrocarbon group having 1 to 12 carbon atoms.
The specific silver layer is formed by applying a solution containing a specific silver layer-forming coating solution, dried and heated, and functions as a sunlight reflecting layer having excellent light reflectance. This will be described in detail below.

  The coating liquid for forming the specific silver layer includes a silver compound represented by the above general formula A (hereinafter also referred to as “silver compound”) and an amine compound represented by the above general formula B (hereinafter referred to as “specific amine compound”). It is also prepared by mixing water and, if necessary, a silver reducing agent and various additives. The specific silver layer forming coating solution contains a silver complex compound formed by reacting at least a part of the silver compound and at least a part of the specific amine compound.

(Silver compound)
The coating solution for forming a specific silver layer contains at least one silver compound represented by the following general formula A. As described above, the silver compound may be included as a silver complex compound.
Ag _n X: General formula A
In general formula A, X is oxygen, sulfur, halogen, cyano, cyanate, carbonate, nitrate, nitrate, sulfate, phosphate, thiocyanate, chlorate, perchlorate, tetrafluoroborate, acetate, acetylacetonate, carboxylate, and these Represents a substituent selected from the derivatives of n represents an integer of 1 to 4.

Specific examples of the silver compound represented by the general formula A include silver oxide, silver thiocyanate, silver sulfide, silver chloride, silver cyanide, silver cyanate, silver carbonate, silver nitrate, silver nitrite, silver sulfate, silver phosphate, Examples thereof include silver perchlorate, silver tetrafluoroborate, silver acetylacetonate, silver acetate, silver lactate, silver oxalate and derivatives thereof. However, it is not limited to these.
Among these, silver oxide, silver carbonate, silver nitrate, and silver acetate are preferable, and silver carbonate and silver oxide are more preferable in that the reflectance is more excellent.

  As a density | concentration of the silver compound conversion amount represented with General formula A in the coating liquid for specific silver layer formation, 3 mass%-50 mass% are preferable with respect to the total mass of a solution, and 5 mass%-30 mass%. Is more preferable. Here, the content of the silver compound equivalent amount means the content of the silver compound itself represented by the general formula A contained in the coating solution for forming a specific silver layer, the silver compound represented by the general formula A, It means the sum of the content of the silver complex compound formed by the reaction of the silver compound and the specific amine compound with the amount converted to the silver compound. The specific silver layer which has the outstanding light reflectance as the silver compound conversion amount represented with General formula A is 3 mass% or more is obtained. Moreover, since the specific silver layer with few cracks is obtained as content of the silver compound conversion amount represented with General formula A is 50 mass% or less, it is advantageous.

(Specific amine compounds)
The coating solution for forming the specific silver layer contains at least one amine compound (specific amine compound) represented by the following general formula B. The specific amine compound is a primary amine compound having a branched β-position. As described above, the specific amine compound may be contained as a silver complex compound formed by reacting with the silver compound.
R ¹¹ —CHR ¹² —CH ₂ —NH ₂ ... General Formula B
In General Formula B, R ¹¹ and R ¹² each independently represent a hydrocarbon group having 1 to 12 carbon atoms.

The hydrocarbon group having 1 to 12 carbon atoms represented by R ¹¹ and R ¹² may be either an unsubstituted alkyl group or a substituted alkyl group.
As an unsubstituted alkyl group, a C1-C8 alkyl group is preferable, for example, a methyl group, an ethyl group, a propyl group, a butyl group etc. are mentioned.
As the substituent of the substituted alkyl group, an aryl group (eg, phenyl group, naphthyl group), an alkoxy group (methoxy group, ethoxy group, etc., preferably 1 to 4 carbon atoms), a halogen atom (eg, chlorine atom, bromine atom) Etc.), cyano group, amino group, heterocyclic group (eg, cyclic groups such as nitrogen-containing heterocyclic groups such as pyrrolidine ring, pyrrole ring and imidazole ring, and oxygen-containing heterocyclic groups such as furan ring and tetrahydrofuran ring) Is mentioned.
Examples of the substituted alkyl group include an arylalkyl group (C1-C4 of the alkyl moiety), a cyanoalkyl group (C1-C4 of the alkyl moiety), and a halogenated alkyl group (C1-C4 of the alkyl moiety). And cycloolefin-bonded alkyl is preferred.
Of the above, at least one of R ¹ and R ² is preferably an ethyl group. Although the reason for this point is not necessarily clear and speculated, the two carbon atoms of the ethyl group and the nitrogen atom and the hydrogen atom of the amino group form a 6-membered ring, so that HOMO (highest occupied orbit, Highest It is considered that complex formation is stabilized because Occupied Molecular Orbital) spreads from a nitrogen atom to an ethyl group.
Furthermore, it is more preferable that R ¹¹ is a butyl group and R ¹² is an ethyl group.

The following compounds are mentioned as an example of a specific amine compound.
Of these, isobutylamine, 2-ethylbutylamine, and 2-ethylhexylamine are preferable, and 2-ethylbutylamine and 2-ethylhexylamine are more preferable.

  The molecular weight of the specific amine compound is preferably in the range of 70 to 400, more preferably in the range of 80 to 300, and particularly preferably in the range of 90 to 200. A molecular weight of 70 or more is advantageous in terms of wettability during coating, and a molecular weight of 400 or less is advantageous in terms of solubility in polar solvents.

  As a density | concentration of the amine compound conversion amount represented by General formula B in the coating liquid for specific silver layer formation, it is 2 mol -30 with respect to 1 mol of silver compound conversion amounts contained in the coating liquid for specific silver layer formation. Mol is preferable, 3 mol to 25 mol is more preferable, and 3 mol to 20 mol is still more preferable. Here, the amine compound equivalent amount is the content of the amine compound itself represented by the general formula B contained in the coating solution for forming the specific silver layer, the amine compound represented by the general formula B, and the silver compound. Means the sum of the content of the silver complex compound formed by the reaction with the amount converted to the specific amine compound. When the amine compound equivalent amount represented by the general formula B is 2 mol or more with respect to 1 mol of the silver compound equivalent amount, the dissolution of the silver compound becomes better. Moreover, the specific silver layer which has the outstanding light reflectance as the conversion amount of the amine compound represented by General formula B is 30 mol or less with respect to 1 mol of silver compound conversion amounts is obtained.

(water)
The specific silver layer forming coating solution contains water. Since it contains water, the solution is used as an aqueous coating solution.
As content of the water in the coating liquid for specific silver layer formation, 3 mol-100 mol are preferable with respect to 1 mol of silver compound conversion amounts in the coating liquid for specific silver layer formation, and 5 mol-50 mol are more. Preferably 5 mol-30 mol are more preferable. When the water content is 3 mol or more, dissolution of the silver compound becomes better. Moreover, the specific silver layer which has the outstanding light reflectance as content of water is 100 mol or less is obtained.

(Solvents other than water)
The coating solution for forming the specific silver layer preferably contains a polar solvent in addition to water.
As the polar solvent other than water, for example, the polar solvent described in paragraph No. [0040] of JP2012-181301A can be used as long as the effects of the present invention are not impaired. The polar solvent can be appropriately selected according to the silver compound and the like.

Examples of polar solvents other than water include alcohol solvents such as methanol, ethanol, propanol, ethylene glycol, glycerin and propylene glycol monomethyl ether, for example acids such as formic acid and acetic acid, and ketones such as acetone, methyl ethyl ketone and cyclohexanone. Solvents such as amide solvents such as formamide, dimethylacetamide and N-methylpyrrolidone, nitrile solvents such as acetonitrile and propionitrile, ester solvents such as methyl acetate and ethyl acetate, such as dimethyl carbonate and diethyl Carbonate-based solvents such as carbonate, ammonia, such as plutamine, isopropylamine, butylamine, monoethanolamine, 2-methylaminoethanol, diethanol Min, butoxypropyl amine, diethyl methyl amine, 2-dimethylaminoethanol, amine solvents such as methyl diethanolamine, thiols solvents, sulfoxide solvents, a halogen-based solvent.
Among these, alcohol solvents, amide solvents, ketone solvents, nitrile solvents, sulfoxide solvents, and amine solvents are preferable, and alcohol solvents and amine solvents are more preferable.
Specifically, methanol, ethanol, propanol, isopropanol, 1-methoxy-2-propanol, acetone, dimethylacetamide, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetonitrile, propionitrile, N-methylpyrrolidone, dimethyl sulfoxide, ammonia, Propylamine, isopropylamine, butylamine, monoethanolamine, 2-methylaminoethanol, diethanolamine, butoxypropylamine, diethylmethylamine, 2-dimethylaminoethanol, and methyldiethanolamine are more preferable. Further, methanol, ethanol, isopropanol, 1-methoxy-2-propanol, acetone, dimethylacetamide, methyl ethyl ketone, methyl isobutyl ketone, acetonitrile, N-methylpyrrolidone, dimethyl sulfoxide, ammonia, isopropylamine, butylamine, and monoethanolamine are preferable. , Methanol, ethanol, isopropanol, 1-methoxy-2-propanol, acetone, methyl ethyl ketone, and isopropylamine are more preferable.

When silver carbonate, silver nitrate, or silver acetate is used as the silver compound, examples of polar solvents other than water include alcohol solvents (preferably methanol, ethanol, isopropanol, 1-methoxy-2-propanol), acids (preferably formic acid, acetic acid). Or a mixed solvent thereof.
When silver oxide is used as the silver compound, an amine solvent (preferably isopropylamine, butylamine, monoethanolamine) is preferable as the polar solvent other than water.

  As content of polar solvents other than water in the coating liquid for specific silver layer formation, 3 mol-100 mol are preferable with respect to 1 mol of silver compound conversion amounts in a solution, and 5 mol-60 mol are more preferable. 10 mol-40 mol is still more preferable. When the content of the polar solvent other than water is 3 mol or more (especially 10 mol or more), the dissolution rate of the silver compound dissolved in the coating solution for forming the specific silver layer is improved, and the light reflectance is excellent. A specific silver layer is obtained. When the content of the polar solvent other than water is 100 mol or less, it is advantageous in terms of liquid stability.

(Reducing agent)
The coating solution for forming a specific silver layer preferably contains a reducing agent for reducing the silver compound and the silver complex compound to metallic silver. By containing the reducing agent, the above reduction reaction is promoted, and the formation of the specific silver layer having a high light reflectance becomes easier.
Examples of reducing agents include hydrazine, acetate hydrazide, trisodium citrate, methyldiethanolamine, dimethylamineborane and other amine compounds, formaldehyde, acetaldehyde and other aldehyde compounds, glucose, ascorbic acid, salicylic acid, tannic acid, pyrogallol, hydroquinone and the like. Inorganic compounds such as organic compounds, metal salts such as sodium, potassium borohydride, ferrous chloride, and iron sulfate, hydrogen iodide, and carbon monoxide.

As the reducing agent, a compound represented by the following general formula C is preferable.
The silver compound and silver complex compound contained in the coating solution for forming the specific silver layer may exist without being reduced at the interface between the specific silver layer and the adjacent layer.
However, the compound represented by the general formula C is formic acid or has both a carboxyl group and an aldehyde group in the molecule, so that the silver compound and silver present at the interface of the specific silver layer It is possible to effectively suppress an adverse effect (for example, a decrease in light reflectance of the specific silver layer) due to the complex compound.
R-COOH: general formula C

  In general formula C, R represents a hydrogen atom or a monovalent functional group having one or more aldehyde groups. Examples of the “monovalent functional group having one or more aldehyde groups” represented by R include an aldehyde group, an alkyl group having 1 to 20 carbon atoms having one or more aldehyde groups, and one or more aldehydes. Examples thereof include an aryl group having 5 to 20 carbon atoms having a group, an amino group having one or more aldehyde groups, and a heterocyclic group having 5 to 20 carbon atoms having one or more aldehyde groups. Preferred are an aldehyde group, a methyl group having one or more aldehyde groups, an ethyl group having one or more aldehyde groups, a benzene ring having one or more aldehyde groups, and the like.

Examples of the compound represented by the general formula C include formic acid, 2-methyl-3-oxopropanoic acid, 3-oxopropanoic acid, phthalaldehyde acid, isophthalaldehyde acid, terephthalaldehyde acid and the like. Among these, formic acid is preferable in that the light reflectance is more excellent.
In addition, the compound represented by the general formula C may be used alone or in combination of two or more.

The content of the compound represented by the general formula C in the coating solution for forming the specific silver layer is preferably in the following range.
When the coating liquid for specific silver layer formation contains the compound represented by general formula C, as content of the compound represented by general formula C in a solution, with respect to the total mass of the coating liquid for specific silver layer formation 0.01% by mass to 20% by mass is preferable, and 0.1% by mass to 10% by mass is more preferable. When the content of the compound represented by the general formula C is 0.01% by mass or more, reducibility is exhibited and the effect of improving the light reflectance is high. When the content of the compound represented by the general formula C is 20% by mass or less, it is advantageous in terms of liquid stability during storage of the coating solution for forming the specific silver layer.

The coating solution for forming a specific silver layer contains additives such as a stabilizer, a leveling agent, a thin film auxiliary agent, and a thermal decomposition reaction accelerator, as necessary, in addition to the above-described silver compound, specific amine compound, and water. But you can.
For details of the above-mentioned additives, reference can be made to the description of paragraph numbers [0037] to [0040] of JP2012-181301A.

  The silver layer 14 is disposed on the surface of the polyester film 22, and the surface of the polyester film 22 includes an undercoat layer that improves the adhesion between the silver layer 14 and the polyester film 22, and the first adjacent layer described above. It is preferable to form at least one layer.

The surface of the polyester film 22 may be subjected to a surface treatment in advance in order to easily form an undercoat layer or a first adjacent layer.
Surface treatment includes UV irradiation, ozone treatment, plasma treatment, corona treatment, flame treatment, and other surface activation treatments, hydrazine, N-methylpyrrolidone, sodium hydroxide solution, alkaline solution such as potassium hydroxide solution And treatment with an acidic solution such as sulfuric acid, hydrochloric acid and nitric acid. Examples of the treatment for removing and cleaning the surface of the polyester film 22 include treatment with an organic solvent such as methanol, ethanol, toluene, ethyl acetate, and acetone, and washing with water to remove attached dust. These surface treatments may be performed in combination of a plurality of types.

-Undercoat layer-
From the viewpoint of adhesion to the adjacent polyester film 22, the undercoat layer preferably contains the same resin as that constituting the polyester film 22 or a resin having an affinity for the resin constituting the polyester film 22.
Examples of the resin contained in the undercoat layer include a thermosetting resin and a thermoplastic resin, and the thermosetting resin and the thermoplastic resin may be used alone or in combination.
Examples of the thermosetting resin include epoxy resins, phenol resins, polyimide resins, polyester resins, polyurethane resins, bismaleimide resins, melamine resins, and isocyanate resins. Examples of the thermoplastic resin include polyolefin resin, phenoxy resin, polyether sulfone, polysulfone, polyphenylene sulfone, polyphenylene sulfide, polyphenyl ether, polyether imide, and the like.
When having at least one of the undercoat layer and the first adjacent layer described above, the compound represented by the general formula C described above is included in the undercoat layer or the first adjacent layer. Since the light reflectance of a silver layer can be improved more, it is preferable.

<Method for forming specific silver layer>
The method of forming the specific silver layer on the surface of the composite film is a coating step of applying the coating liquid for forming the specific silver layer described above to the surface of the composite film, a drying step of drying the solution applied to the surface of the composite film, And a heating step of heating.
Details of the specific silver layer forming coating solution used in the coating step are as described above.
The coating amount for coating the specific silver layer forming coating solution on the surface of the composite film is determined according to the thickness of the specific silver layer.

  The coating can be performed by a coating method using a conventionally known coating apparatus such as a gravure coater, a reverse coater, a die coater, a blade coater, a roll coater, an air knife coater, a screen coater, a bar coater, or a curtain coater.

In one embodiment of the method for forming the specific silver layer, the coating step, the drying step, and the heating step are performed continuously.
The drying step and the heating step can be performed as one step (hereinafter also referred to as “dry heating step”). Through both the drying step and the heating step, or the heating and drying step, the reduction reaction of the silver compound proceeds to form a silver layer.
The heating method may be any method as long as it can be heated, for example, a method in which warm air or hot air is blown to the film to heat, a method in which radiant heat is applied to the film to increase the film temperature, and a base material A method of heating the film to heat the film, a method combining the above methods, or the like can be selected as appropriate.

Moreover, the specific silver layer formed by application | coating of the solution containing a silver complex compound and drying may be heat-processed after the below-mentioned 2nd adjacent layer formation process is complete | finished.
The drying conditions are not particularly limited, and any conditions may be used as long as the solvent is dried.
The conditions for the heat treatment are 15 minutes to 2 hours in the temperature range of 80 ° C to 120 ° C, or 5 minutes to 1 hour in the temperature range of 121 ° C to 150 ° C, or 1 in the temperature range of 151 ° C to 200 ° C. The time is preferably from 30 minutes to 30 minutes, and more preferably from 1 minute 30 seconds to 15 minutes in the temperature range of 165 ° C to 200 ° C.

<Second adjacent layer>
In the reflector for solar power generation according to the embodiment included in the present invention, a second adjacent layer containing a corrosion inhibitor for preventing silver corrosion is provided between the silver layer and the first adhesive layer described later. It may be.
It is preferable that a 2nd adjacent layer contains the corrosion inhibitor and binder resin which prevent silver corrosion.
Examples of the binder resin include a thermosetting resin and a thermoplastic resin, and the thermosetting resin and the thermoplastic resin may be used alone or in combination.
Examples of the thermosetting resin include epoxy resins, phenol resins, polyimide resins, polyester resins, polyurethane resins, bismaleimide resins, melamine resins, and isocyanate resins. Examples of the thermoplastic resin include polyolefin resin, phenoxy resin, polyether sulfone, polysulfone, polyphenylene sulfone, polyphenylene sulfide, polyphenyl ether, polyether imide, and the like.

(Corrosion inhibitor to prevent silver corrosion)
Corrosion inhibitors that prevent silver corrosion have the function of preventing discoloration of the silver layer, such as thioether compounds, thiol compounds, Ni organic compounds, benzotriazole compounds, imidazole compounds, oxazole compounds, tetrazaindene compounds, pyrimidine compounds And thiadiazole compounds. The content of the corrosion inhibitor for preventing silver corrosion contained in the second adjacent layer is preferably 0.001% by mass to 20% by mass with respect to the total mass of the second adjacent layer.

  As shown in FIG. 1 and FIG. 2, the reflector for solar power generation according to the embodiment included in the present invention comprises a silver layer 14 formed on a composite film and a glass substrate 12 as a first adhesive layer 32. It has the structure laminated | stacked through.

<Glass base material>
The glass substrate 12 preferably has a thickness in the range of 0.9 mm or more and 5.0 mm or less from the viewpoint of maintaining durability under weather conditions in a place where solar power generation facilities are installed. A commercially available glass plate may be used as the glass substrate 12. What is marketed especially for solar glass is preferable. For example, “Optiwhite” (registered trademark) and “Microwhite” (registered trademark) sold by Pilkington Group Limited are preferable. The thickness of the glass substrate 12 is more preferably in the range of 0.9 mm to 4.5 mm, and particularly preferably in the range of 0.9 mm to 4.0 mm, in terms of excellent bending resistance.

<First adhesive layer>
The first adhesive layer 32 may be formed using a known adhesive composition. For example, an adhesive containing a resin selected from an acrylic resin, a urethane resin, a polyester resin, a polyvinyl acetate resin, a nitrile rubber, and the like. A composition. From the viewpoint of weather resistance and adhesiveness, an adhesive composition containing an acrylic resin or a urethane resin is particularly preferable.
The adhesive composition containing an acrylic resin is particularly excellent in weather resistance. Moreover, the adhesive composition containing a urethane resin divides polyisocyanate and polyol into two liquids, and a two-liquid mixed adhesive composition that mixes these two liquids at the time of use provides a strong adhesive strength. This is preferable.
When manufacturing the solar power generation reflector of the embodiment of the present invention, the first adhesive layer 32 may be provided on the surface of the glass substrate 12 or the silver layer 14 disposed on the surface of the composite film 20. It may be provided on the surface opposite to the side having the composite film 20 or both of them.

  The film thickness of the adhesive layer 32 is preferably in the range of 1 μm to 20 μm, more preferably in the range of 3 μm to 18 μm, particularly in the range of 5 μm to 15 μm, from the viewpoints of adhesion, ease of formation, and the like. Even more preferably.

<Other layers formed as desired>
In the solar power generation reflector of the embodiment of the present invention, a surface coating layer (not shown) may be formed on the surface of the glass substrate 12 opposite to the side on which the silver layer 14 is provided.
Further, an adhesive layer (not shown) may be provided between the polyester film 22 and the first weathering layer 24 in the composite film 20.
Examples of the surface coating layer include a water repellent layer containing a water repellent resin such as a fluororesin and a siloxane polymer, and a superhydrophilic layer containing titanium oxide having photocatalytic activity that generates radicals upon light irradiation.

(Holding member)
The reflector for solar power generation according to the embodiment of the present invention is also used for the solar power generator reflector of any of the tower type solar power generation equipment, parabolic trough solar power generation equipment, linear Fresnel type solar power generation equipment, and dish type solar power generation equipment. Can be used. In particular, it is useful as a reflector for solar power generation used in a tower type solar power generation facility that requires a high reflectance. Moreover, it is useful as a reflector for solar power generation that is used for a linear Fresnel solar power generation facility that uses a thin solar power reflector for bending.
The solar power generation reflector is held by a holding member capable of tracking the sun so that sunlight is reflected by the heat collecting member. There is no restriction | limiting in particular as a holding member, The form which supports several places of the reflector plate for solar thermal power generation with a rod-shaped holding member is preferable so that the reflector plate for solar thermal power generation can be hold | maintained while maintaining a desired shape.
The reflector for solar power generation according to the embodiment of the present invention is excellent in weather resistance and flex resistance. Therefore, a holding member that changes the degree of bending of the silver layer, which is a reflection surface of sunlight, according to the position of the sun, for example, a holding member as described in International Patent Publication No. 2011/088685, It is also possible to hold the solar power generation reflector of the embodiment.

  Hereinafter, the embodiments of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof.

[Example 1]
<Preparation of composite film>
<Preparation of composite film substrate>
-Synthesis of polyester-
About 123 kg of bis (hydroxyethyl) terephthalate was previously charged in a slurry of 100 kg of high-purity terephthalic acid (manufactured by Mitsui Chemicals) and 45 kg of ethylene glycol (manufactured by Nippon Shokubai Co., Ltd.), at a temperature of 250 ° C. and a pressure of 1. The esterification reaction tank maintained at 2 × 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.
As the titanium alkoxide compound, the titanium alkoxide compound (Ti content = 4.44 mass%) synthesized in Example 1 of paragraph 0083 of JP-A-2005-340616 was used.

-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 on a metal drum to produce an unstretched base having a thickness of 3 mm. Thereafter, the film was stretched 3.4 times in the longitudinal direction (hereinafter also referred to as “MD”) at 90 ° C., and then the coating solution for forming the undercoat layer described below was applied to one surface of the polyethylene terephthalate support. Is applied by an in-line coating method and stretched in the direction perpendicular to MD (hereinafter also referred to as “TD”) after MD stretching so that the thickness becomes 5.1 ml / m ² . An undercoat layer was formed. The TD stretching temperature is 105 ° C., stretched 4.5 times in the TD direction, heat-treated for 15 seconds at a film surface of 200 ° C., MD relaxation rate of 5% and TD relaxation rate of 11% at 190 ° C. MD and TD were subjected to thermal relaxation to obtain a biaxially stretched polyethylene terephthalate film (hereinafter referred to as “PET base film 1”) having a thickness of 250 μm.

-Preparation of coating solution for undercoat layer formation-
The following components were mixed to prepare a coating solution for forming an undercoat layer.
<Composition of coating solution for undercoat layer formation>
-Polyolefin resin aqueous dispersion (Arrowbase (registered trademark) SE-1013N, manufactured by Unitika Ltd., solid content concentration: 20% by mass) ... 120 parts by mass-Oxazoline-based crosslinking agent (Epocross (registered trademark) WS-700 , Manufactured by Nippon Shokubai Co., Ltd., solid content concentration: 25% by mass) ... 39 parts by mass Acrylic resin aqueous dispersion (AS-563A, manufactured by Daicel Finechem Co., Ltd., latex having a solid content concentration of 28% by mass)・ 87 parts by mass ・ Fluorosurfactant (sodium-bis (3, 3, 4, 4, 5, 5, 6, 6-nonafluoro) -2-sulfonite oxysuccinate, manufactured by Sankyo Chemical Co., Ltd. , Concentration 1 mass%) ... 0.9 parts by mass Distilled water ... 753 parts by mass

-Preparation of white inorganic fine particle dispersion-
Components in the following composition were mixed, and the mixture was dispersed by a dynomill type disperser to obtain a white inorganic fine particle dispersion having a volume average particle size of 0.55 μm.
<Composition of white inorganic fine particle dispersion>
・ Titanium oxide (Taipeke (registered trademark) CR-95, manufactured by Ishihara Sangyo Co., Ltd., solid content concentration: 100% by mass; white pigment): 1000 parts by mass ・ Polyvinyl alcohol (PVA-105, manufactured by Kuraray Co., Ltd.) 10% by weight aqueous solution with a solid content concentration of 100% by mass: 500 parts by mass Surfactant (Demol (registered trademark) EP, manufactured by Kao Corporation, solid content concentration: 25% by mass): 12 parts by mass Distilled water ... 631 parts by mass Preservative (AF337, manufactured by Daito Chemical Co., Ltd., solid content concentration: 3.5% by mass) ... 6.5 parts by mass

<Formation of weather-resistant layer>
-Preparation of coating solution for forming the first weathering layer-
Each component shown in the composition of the following coating solution for forming a first weathering layer was mixed to prepare a coating solution for forming a first weathering layer.
<Composition of coating solution for forming first weather resistant layer>
-Silicone-acrylic composite resin (Ceranate (registered trademark) WSA-1070, manufactured by DIC Corporation, solid content concentration: 40% by mass) ... 188 parts by mass-Oxazoline-based crosslinking agent (Epocross (registered trademark) WS-700 , Manufactured by Nippon Shokubai Co., Ltd., solid content concentration: 25% by mass) ... 58 parts by mass Fluorosurfactant (sodium-bis (3, 3, 4, 4, 5, 5, 6, 6-nonafluoro) -2-sulfonite oxysuccinate (manufactured by Sankyo Chemical Co., Ltd., concentration 1% by mass)) 9.4 parts by mass, the above white inorganic fine particle dispersion ... 254 parts by mass, dibasic ammonium phosphate (Secondary ammonium phosphate for food addition, manufactured by Nippon Chemical Industry Co., Ltd., 35% by weight aqueous solution) ... 6.2 parts by mass -formation of first weathering layer-
While the PET base film 1 having the undercoat layer was conveyed at a conveyance speed of 80 m / min, a surface opposite to the surface on which the undercoat layer was formed was subjected to corona discharge treatment under the condition of 730 J / m ² . Subsequently, the coating solution for forming the first weathering layer is applied to the surface subjected to the corona discharge treatment so that the amount of titanium oxide is 10.5 g / m ² in terms of the applied mass, and then at 170 ° C. for 2 minutes. Drying was performed to form a first weather-resistant layer having a dry thickness of 8 μm.

-Preparation of coating solution for forming second weather resistant layer-
Each component shown in the composition of the following coating solution for forming a weather resistant layer was mixed to prepare a coating solution for forming a second weather resistant layer.
<Composition of coating solution for forming second weather resistant layer>
・ Fluororesin (Obrigato (registered trademark) SW0011F, manufactured by AGC Co-Tech, diluted with water so that the solid content concentration is 36% by mass) 43 parts by mass ・ Oxazoline-based crosslinking agent (Epocross (registered trademark)) WS-700, manufactured by Nippon Shokubai Co., Ltd., solid concentration 25% by mass) ... 12 parts by mass Nonionic surfactant (Naroacty (registered trademark) CL95, Sanyo Chemical Industries, Ltd., solid concentration 1) 1.5% by mass / dibasic ammonium phosphate (diluted ammonium phosphate for food use, manufactured by Nippon Chemical Industry Co., Ltd., 35% by mass aqueous solution) ... 1.3 parts by mass / Lubricant (Chemipearl (registered trademark) W950, manufactured by Mitsui Chemicals, solution diluted with water so that the solid content concentration becomes 5% by mass) 25.7 parts by mass Matting agent (Snowtex (registered trademark)) UP, Nissan Chemical Co., Ltd., a solution diluted with water so that the solid content concentration is 2% by mass) 5 parts by weight [Snowtex (registered trademark) UP, Nissan Chemical Co., Ltd., solid content 2% Water dilution)
-Silane coupling agent (TSL8340, Momentive Performance Japan, hydrolyzate with a solid content concentration of 2% by mass) ... 5 parts by mass-Distilled water ... 114 parts by mass-Formation of second weathering layer-
The obtained coating solution for forming the second weathering layer was applied on the first weathering layer so that the coating weight of the fluororesin was 1.5 g / m ² and dried at 170 ° C. for 2 minutes. Then, a second weathering layer having a dry thickness of 1.5 μm was formed.
By the above, the composite film 1 which provided the 1st weathering layer and the 2nd weathering layer on the surface opposite to the surface which has an undercoat of PET base film 1 which has an undercoat on one surface (this invention) Composite film according to an embodiment of the present invention.

The water vapor transmission rate of the composite film 1 produced as described above was measured by the following measuring method, and the results are shown in Table 1 described later.
<Method of measuring water vapor transmission rate>
According to JIS K7129 (2008), the water vapor permeability of the composite film 1 was measured with a water vapor permeability tester PERMATRAN W3 / 33 manufactured by MOCON in an environment of a temperature of 40 ° C. and a relative humidity of 90%.

-Formation of silver layer-
A coating solution for forming a silver layer prepared by the following method is applied to the surface of the undercoat layer of the composite film 1 by a bar coating method and dried at 165 ° C. for 2 minutes to form a silver layer having a thickness of 0.1 μm. Formed.
<Preparation of silver layer forming coating solution>
As a silver complexing agent, 12.9 parts by mass of 2-ethylhexylamine (2EHA), 2.7 parts by mass of silver carbonate, and 1.8 parts by mass of water were mixed, and further 9.6 parts by mass of methanol was added and stirred. By doing this, the coating liquid for silver layer formation was prepared.
Thus, a film mirror 1 having a silver layer on the surface of the composite film 1 was produced.

  -Bonding with glass substrate using adhesive transfer tape-

Using a highly transparent adhesive transfer tape (Sumitomo 3M Co., Ltd., model number: 1466-1), one side of a sufficiently cleaned glass substrate (pickington's microhite, thickness 1 mm) and the silver layer of the film mirror 1 are used. By pasting together, a reflector for solar power generation (rectangular shape having a length of 100 cm and a width of 50 cm) was obtained.
−End face sealing−
The end faces of the four circumferences of the prepared solar power generation reflecting plate were sealed as follows, and the solar power generation reflecting plate 1 according to Example 1 was obtained.
The end face sealing at the four corners was performed using an aluminum tape.

[Example 2]
A PET base film 2 having a thickness of 188 μm, in the same manner as the PET base film 1 in Example 1, except that an unstretched base having a thickness of 0.75 mm was prepared instead of the non-stretched base having a thickness of 3 mm. Was made. Using this PET substrate film 2, a solar power generation reflector 2 according to Example 2 was obtained in the same manner as in Example 1 except that the composite film 2 was produced in the same procedure as in Example 1. .
In addition, the water-vapor-permeation rate of the composite film 2 in the reflector 2 for solar thermal power generation was measured by the above-mentioned method, and the result was described in Table 1 mentioned later.

[Comparative Example 1]
A PET base film C1 having a thickness of 125 μm was obtained in the same manner as the PET base film 1 in Example 1, except that an unstretched base having a thickness of 0.6 mm was produced instead of the non-stretched base having a thickness of 3 mm. Was made. A solar power generation reflector C1 according to Comparative Example 1 was obtained in the same manner as in Example 1 except that the composite film C1 was produced in the same procedure as in Example 1 using the PET base film C1.
In addition, the water vapor transmission rate of the composite film C1 in the reflector 2 for solar thermal power generation was measured by the above-mentioned method, and the result was described in Table 1 mentioned later.

[Example 3]
A solar power generation reflector 3 according to Example 3 was produced in the same manner as Example 1 except that the first weathering layer and the second weathering layer were not formed. In addition, the water vapor transmission rate of the composite film used for the solar power generation reflector 3 without the first weathering layer and the second weathering layer was measured by the method described above, and the results are shown in Table 1 described later. .

[Comparative Example 2]
Instead of the glass substrate, a KB film G01 (made by Kimoto Co., Ltd., thickness 188 μm, pencil hardness 2 to 3 H on the hard coat layer surface), which is a polyethylene terephthalate film having a hard coat layer, has a hard coat layer. A solar power generation reflector C2 according to Comparative Example 2 was produced in the same manner as in Example 1, except that the surface opposite to the side and the surface of the undercoat layer of the composite film were in contact with each other.

[Comparative Example 3]
In place of the glass substrate, a polyethylene terephthalate film (Toyobo Co., Ltd. Cosmo Shine (registered trademark) A4100, thickness 188 μm) was used. An undercoat layer was provided in the same manner as in Example 1. Thereafter, the solar heat according to Comparative Example 3 was made in the same manner as in Example 1 except that the surface of the undercoat layer of the polyethylene terephthalate film was bonded to the silver layer of the film mirror 1 produced in Example 1. A power generation reflector C3 was produced.

[Example 4]
A highly transparent adhesive transfer tape (manufactured by Sumitomo 3M Limited, model number: 8146-1) is used on the surface opposite to the side having the undercoat layer of the PET base film 1 produced in the same manner as in Example 1. Thus, an aluminum foil having a thickness of 100 μm was attached to obtain a composite film 4. The water vapor permeability of the obtained composite film 4 was measured by the measurement method described above, and the results are shown in Table 1 described later.
A solar power generation reflector 4 according to Example 4 was produced in the same manner as in Example 1 except that the composite film 4 produced as described above was used instead of the composite film 1.

[Example 5]
In place of the undercoat layer, the following coating solution for forming the first adjacent layer was applied and dried to form the first adjacent layer having a thickness of 10 μm. In the same manner as in the production, a PET base film 5 was produced.
-Preparation of coating solution for forming first adjacent layer-
The following components were mixed to prepare a coating solution for forming a first adjacent layer.
<Composition of coating solution for forming first adjacent layer>
Defenser FH-700 (manufactured by DIC Corporation) ... 45.00 parts by mass Isopropyl alcohol (IPA) -dispersed silica IPA-ST, manufactured by Nissan Chemical Co., Ltd .... 16.67 parts by mass Isopropyl alcohol ... 38.33 parts by mass benzimidazole ... 1.23 parts by mass

  A solar power generation reflector 5 according to Example 5 was produced in the same manner as in Example 1 except that the produced PET base film 3 was used in place of the PET base film 1.

[Example 6]
A PET base film 6 was prepared in the same manner as in the preparation of the PET base film 1 in Example 1, except that no undercoat layer was formed.
A silver layer was formed in the same manner as in Example 1 on the surface of the PET base film 6 opposite to the side on which the first weathering layer was formed.
The following coating solution for forming a second adjacent layer was applied to the surface of the silver layer and dried to form a second adjacent layer having a thickness of 10 μm. -Preparation of a coating solution for forming a second adjacent layer-
The following components were mixed to prepare a coating solution for forming a second adjacent layer.
<Composition of coating solution for forming second adjacent layer>

Defender FH-700 (manufactured by DIC Corporation) 45.00 parts by mass Isopropyl alcohol (IPA) dispersed silica IPA-ST, manufactured by Nissan Chemical Co., Ltd.)
... 16.67 parts by mass Isopropyl alcohol ... 38.33 parts by mass Benzimidazole ... 1.23 parts by mass

The surface of the second adjacent layer and the glass substrate were bonded together using a highly transparent adhesive transfer tape (manufactured by Sumitomo 3M Limited, model number: 8146-1) in the same manner as in Example 1. A reflector 6 for solar power generation according to Example 6 was obtained.

[Example 7]
Reflector for solar power generation according to Example 7 in the same manner as in Example 1 except that a surface coating layer was formed as follows on the surface of the glass substrate opposite to the film mirror 1 side. 7 was obtained.
<Formation of surface coating layer>
-Preparation of silicate oligomer liquid A1-
Silicate MS-51 (Mitsubishi Chemical Corporation) 1.54 parts by mass, ethanol 40.74 parts by mass, pure water 51.94 parts by mass, and polyoxyethylene lauryl ether which is a nonionic surfactant: EMALEX (Registered trademark) 715 (manufactured by Nippon Emulsion Co., Ltd., diluted with 0.5% pure water) 5.78 parts by mass were mixed and stirred at room temperature (25 ° C.) for 24 hours to prepare silicate oligomer liquid A1. .
Silicate MS-51 is a siloxane oligomer represented by the following structural formula, wherein R ^{1 to} R ⁴ are all methyl groups, and the average of n is 5.

-Preparation of aqueous coating agent B1-
41.28 parts by mass of the obtained silicate oligomer liquid A1, 29.31 parts by mass of pure water, 17.11 parts by mass of ethanol, Emalex (registered trademark) 715 (manufactured by Nippon Emulsion Co., Ltd., diluted with 0.5% pure water) 2 .16 parts by mass, small particle size silica: Snowtex (registered trademark) O-33 (trade name: manufactured by Nissan Chemical Industries, average primary particle size: 10-20 nm) 1.53 parts by mass, hollow silica particles: through rear ( Aqueous coating agent B1 was produced by mixing 3.01 parts by mass of registered trademark 1110 (trade name, JGC Catalysts & Chemicals, average primary particle size 50 nm).
The obtained aqueous coating agent B1 was applied to the surface of the glass substrate with a coating amount of a dry film thickness of 150 nm to form a coating film. The coating film was dried at room temperature (25 ° C.) for 30 minutes to form a surface coating layer on the glass substrate.

[Example 8]
A solar power generation reflector 8 according to Example 8 was obtained in the same manner as in Example 1 except that the silver layer forming coating solution prepared as described below was used.
<Preparation of silver layer forming coating solution>
2-ethylhexylammonium 2-ethylcarbamate 32.5 parts by mass, isopropanol 48.5 parts by mass, isopropylamine 5.0 parts by mass, dimethylaminoethanol 2.0 parts by mass, and silver oxide 11.0 parts by mass were mixed. Then, a coating solution for forming a silver layer was prepared by stirring at room temperature for 1 hour.

The following evaluation was performed about each reflector for solar power generation produced as mentioned above.
Evaluation of the weather resistance of the reflector for solar power generation was performed based on the evaluation by the following heat resistance test and the evaluation by the light resistance test.
The results are shown in Table 1 below.

<Measurement of sunlight reflectance>
A spectrophotometer (model UV-3100) manufactured by Shimadzu Corporation is modified with an integrating sphere reflection accessory so that the incident angle of incident light is 5 ° with respect to the normal of the reflecting surface. After adjustment, the regular reflectance at a reflection angle of 5 ° was measured. The total energy for each wavelength, which is obtained by multiplying the measured regular reflectance for each wavelength by the irradiation energy of sunlight on the ground surface described in ASTM G173-03 for each 1 nm from 280 nm to 2500 nm, is irradiated with all sunlight. The value divided by energy was taken as the solar reflectance.

<Moisture and heat resistance test>
Each reflector for solar thermal power generation was subjected to forced deterioration for 1000 hours under conditions of a temperature of 85 ° C. and a relative humidity of 85%, and the solar reflectance was measured by the same method as described above. From the percentage of solar reflectance of the solar power generation reflector after forced degradation to the solar reflectance of the solar power generation reflector before forced degradation, calculate the solar reflectance reduction rate, Furthermore, the visual change was evaluated. The evaluation criteria for evaluation based on the rate of decrease in solar reflectance in the wet heat resistance test are described below. In Table 1 to be described later, the evaluation based on the rate of decrease in the solar reflectance in the moisture and heat resistance test is described in the “Reflectance” column of the “Moisture and Heat Resistance Test”, and the visual change is evaluated in the “Visual” column. Described. “-” In the visual column means that there was no visual abnormality.
5: Decrease rate of sunlight reflectance is less than 5%.
4: Decrease rate of sunlight reflectance is 5% or more and less than 10%.
3: Decrease rate of sunlight reflectance is 10% or more and less than 15%.
2: Decrease rate of sunlight reflectance is 15% or more and less than 20%.
1: Decrease rate of sunlight reflectance is 20% or more.

<Light resistance test of solar reflectance>
Each solar power generation reflector was irradiated with ultraviolet rays for 100 hours under an environment of 90 mW / cm ² illuminance, temperature 60 ° C., and relative humidity 50% using an I-super UV tester manufactured by Iwasaki Electric Co., Ltd. After that, the solar reflectance was measured by the above method, the decrease rate of the solar reflectance before and after the ultraviolet irradiation was calculated in the same manner, and the visual change was evaluated. The evaluation criteria for evaluation based on the rate of decrease in sunlight reflectance in the light resistance test are described below. In Table 1 to be described later, the evaluation based on the decrease rate of the solar reflectance in the light resistance test is described in the “Reflectance” column of the “Light Resistance Test”, and the visual change is evaluated in the “Visual” column. Described. “-” In the visual column means that there was no visual abnormality.
5: Decrease rate of sunlight reflectance is less than 5%.
4: Decrease rate of sunlight reflectance is 5% or more and less than 10%.
3: Decrease rate of sunlight reflectance is 10% or more and less than 15%.
2: Decrease rate of sunlight reflectance is 15% or more and less than 20%.
1: Decrease rate of sunlight reflectance is 20% or more.

<Detergency test>
Applying a load of 10 g / cm ² to the light incident side surface of each solar thermal power reflector on a light incident side surface with 5% by weight of water suspended in Fremantle Sand (manufactured by Mitsubishi Corporation Building Materials Co., Ltd.) Rubbed for a minute. Then, the visual evaluation and the decrease rate of the solar reflectance before and after the cleaning were calculated and evaluated according to the following evaluation criteria. The evaluation results are shown in the column of “Detergency” in Table 1.
5: There is no visual damage and the decrease rate of sunlight reflectance is less than 1%.
4: There are few scratches visually, and the rate of decrease in solar reflectance is 1% or more and less than 5%.
3: There is a crack visually and the fall rate of sunlight reflectance is 5% or more and less than 10%.
2: There is a crack visually and the fall rate of sunlight reflectance is 10% or more and less than 15%.
1: There is a damage | wound visually and the fall rate of sunlight reflectance is 15% or more.

  From the results shown in Table 1, it can be seen that the reflector for solar power generation according to the embodiment of the present invention is excellent in weather resistance and cleanability.

The disclosure of Japanese Patent Application No. 2014-144303 filed on July 14, 2014 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.

Claims (15)

A composite film having a water vapor transmission rate of 20 g / m ² · day or less;
A silver layer disposed on one surface of the composite film;
A glass substrate provided on the silver layer, on which sunlight is incident;
A solar power generation reflector having a first adhesive layer disposed between the silver layer and the glass substrate.   The solar power generation reflector according to claim 1, wherein the composite film has a resin base material and at least one weathering layer formed on the resin base material in order from the side close to the silver layer.   The said composite film has a polyester film, the 1st weather resistance layer containing a silicone-acryl composite resin, and the 2nd weather resistance layer containing a fluororesin in order from the side close | similar to the said silver layer. Item 3. A solar power generation reflector according to Item 2.   The solar power generation reflector according to claim 1, wherein the composite film includes a polyester film, a second adhesive layer, and an aluminum layer in order from the side closer to the silver layer.   The reflector for solar power generation according to claim 3 or 4, wherein the polyester film is a biaxially stretched polyester film having a thickness of 150 µm or more and 500 µm or less.   The composite film has a first adjacent layer containing a corrosion inhibitor for preventing silver corrosion as an outermost layer on the side having the silver layer, and the silver layer is disposed on the surface of the first adjacent layer. The reflector for solar thermal power generation according to any one of claims 1 to 5.   The solar heat according to any one of claims 1 to 6, further comprising a second adjacent layer containing a corrosion inhibitor for preventing silver corrosion between the silver layer and the first adhesive layer. Reflector for power generation.   The reflector for solar power generation according to any one of claims 1 to 7, further comprising a surface coating layer on a surface of the glass substrate opposite to the first adhesive layer side. The silver layer is a layer formed by coating a solution containing at least a silver compound represented by the following general formula A, an amine compound represented by the following general formula B, and water. The reflector for solar power generation of any one of Claim 8.
Ag _n X: General formula A
R ¹¹ —CHR ¹² —CH ₂ —NH ₂ ... General Formula B
In the above general formula A, X is oxygen, sulfur, halogen, cyano, cyanate, carbonate, nitrate, nitrite, sulfate, phosphate, thiocyanate, chlorate, perchlorate, tetrafluoroborate, acetate, acetylacetonate, carboxylate, and The substituent selected from these derivatives is represented, and n represents the integer of 1-4.
In the general formula B, R ¹¹ and R ¹² each independently represent a hydrocarbon group having 1 to 12 carbon atoms.   The reflector for solar power generation according to claim 9, wherein the silver compound is at least one selected from silver oxide, silver carbonate, silver nitrate, and silver acetate.   The solar power generation reflector according to claim 9, wherein the solution further contains a polar solvent other than water.   The solar power generation reflector according to claim 11, wherein the polar solvent other than water is an alcohol solvent or an amine solvent.   The solution is a silver complex compound formed by reacting the amount of the silver compound represented by the general formula A and the silver compound represented by the general formula A and the amine compound represented by the general formula B. The amount of the amine compound represented by the general formula B and the silver complex compound represented by the general formula B with respect to 1 mol in total with the amount converted to the silver compound represented by the general formula A The total amount of 2 mol to 30 mol with respect to the amount converted to the compound, 3 mol to 100 mol of water, and 3 mol to 100 mol of polar solvent other than the water. 12. A reflector for solar power generation according to 12.   The solar power generation reflector according to any one of claims 9 to 13, wherein the solution further contains a reducing agent. The reflector for solar power generation according to claim 14, wherein the reducing agent is a compound represented by the following general formula C.
R-COOH: general formula C
In the general formula C, R represents a hydrogen atom or a monovalent functional group having one or more aldehyde groups.