WO2015064312A1

WO2015064312A1 - Film mirror and light reflection device for solar heat reflection using same

Info

Publication number: WO2015064312A1
Application number: PCT/JP2014/076720
Authority: WO
Inventors: 光範後藤
Original assignee: コニカミノルタ株式会社
Priority date: 2013-10-29
Filing date: 2014-10-06
Publication date: 2015-05-07
Also published as: JP2016224076A

Abstract

[Problem] To provide: a film mirror which is capable of preventing a reduction in reflectance when used affixed to a support substrate; and a light reflection device using the mirror. [Solution] Provided is a film mirror comprising, in order from the light incident side: a translucent resin layer; a resin substrate; a light reflection layer; a protective layer which contains particles and is 20-75 µm thick; and an adhesive layer which is in contact with the protective layer.

Description

Film mirror and light reflecting device for solar heat reflection using the same

The present invention relates to a film mirror and a light reflecting device for solar heat reflection using the film mirror. More specifically, the present invention relates to a film mirror capable of realizing a more uniform reflectance of a light reflecting surface and a solar heat reflecting light reflecting device using the film mirror.

In recent years, global warming has become more serious, and the main cause is said to be carbon dioxide, a fossil fuel.

Power generation technology that uses natural energy such as sunlight, wind power, and geothermal heat is being developed as an alternative energy to fossil fuels. However, power generation using sunlight is particularly focused because of its abundance of stability and energy. Has been.

In solar thermal power generation, a condensing device that reflects sunlight by a reflector (mirror) and condenses it in one place is used. Since the reflector is exposed to ultraviolet rays, heat, wind and rain, and sandstorms caused by sunlight, a glass light reflector has been conventionally used from the viewpoint of durability. However, the light reflector made of glass has a problem that it is damaged during transportation, and because it is heavy, a high-strength gantry is required to install it, which increases the construction cost of the plant.

In order to deal with the above problem, an attempt has been made to replace a glass mirror with a resin reflecting mirror as described in, for example, US Pat. No. 4,307,150. The resin reflection mirror described in Patent Document 1 has a pressure-sensitive adhesive layer on the first surface of the polyester film, a mirror surface made of an aluminum vapor deposition film on the second surface, and is weather resistant. In order to improve the property, a coating made of three kinds of specific monomers is provided on the aluminum layer. Patent Document 1 describes that a resin reflection mirror having such a configuration can be attached to a substrate and used in a reflection device.

When the film mirror according to the above prior art is actually used in a light reflecting device, for example, pasted on a curved surface having a large curvature, the reflectance may be lower than the initial state. The light reflecting device is provided with a large number of reflecting mirrors so as to have a large area as a whole, thereby condensing sunlight into a certain region to generate electric power. The film mirror once applied is continuously used for light collection and power generation for a long period of 10 years or more. For this reason, there is a fear that the reflectivity may be lowered by changing the surface state of the reflecting surface. Therefore, there is still room for improvement in the prior art in terms of preventing the reflectance from decreasing and maintaining the initial reflectance. Therefore, an object of the present invention is to provide a film mirror that solves the problem of a decrease in reflectance when a film mirror is used, and that can maintain a high reflectance, and a light reflecting device using the film mirror.

As a result of intensive studies in view of the above problems, the present inventor has found that the above object of the present invention is achieved by the following configuration. That is, according to the present invention,
From the light incident side
A translucent resin layer;
A resin substrate;
A light reflecting layer;
A protective layer containing particles and having a thickness of 20 to 75 μm;
An adhesive layer in contact with the protective layer;
Are provided in order.

It is a schematic sectional drawing which shows the structure of the film mirror which concerns on one Embodiment of this invention. It is a schematic sectional drawing which shows the structure of the film mirror which concerns on another embodiment of this invention. It is a figure for demonstrating the measuring method of the particle size of particle | grains.

Hereinafter, the form for implementing the film mirror of this invention and the light reflection apparatus using the same is demonstrated in detail.

[Film mirror]
The overall configuration of the film mirror of the present invention will be described with reference to the drawings. In addition, the dimension ratio of drawing is exaggerated on account of description, and may differ from an actual ratio.

FIG. 1 is a diagram schematically showing a cross section of a film mirror according to an embodiment of the present invention. In FIG. 1, the film mirror 10 is laminated | stacked in order of the translucent resin layer 11, the resin base material 12, the light reflection layer 13, the corrosion prevention layer 14, the protective layer 15, and the adhesion layer 16 from the light-incidence side. In the protective layer 15, particles 17 are mixed in the resin matrix, and the surface in contact with the adhesive layer is uneven. The present invention is characterized in that a protective layer having a thickness of 20 to 75 μm including the particles 17 is provided between the adhesive layer and the light reflecting layer.

In the present invention, by providing a protective layer having a specific thickness between the adhesive layer and the light reflecting layer, it is possible to prevent distortion of the light reflecting layer when the film mirror is installed on the base material, and to prevent a decrease in reflectance. can do. Moreover, the adhesiveness of an adhesion layer and a protective layer can be improved by mixing particle | grains in a protective layer and making a surface rough. Thereby, peeling between the adhesion layer and the protective layer can be suppressed even after long-term use. It is possible to prevent the surface state of the light reflecting surface from being roughened due to peeling between the protective layer and the adhesive layer, and as a result, the reflectance is not lowered.

FIG. 2 is a diagram schematically showing a cross section of a film mirror according to a more preferred embodiment of the present invention. In FIG. 2, the film mirror 20 has particles in the hard coat layer 28, the translucent resin layer 21, the resin base material 22, the anchor layer 30, the light reflection layer 23, the corrosion prevention layer 24, and the resin matrix from the light incident side. 27, a protective layer 25 having a thickness of 20 to 75 μm and an adhesive layer 26 are laminated in this order. The hard coat layer 28 is less susceptible to external damage and air, and these contribute to the durability of the film mirror. The anchor layer contributes to the adhesion between the resin base material 22 and the light reflecting layer 23.

The total thickness of the film mirror according to the present invention is preferably 80 to 300 μm, more preferably 80 to 200 μm, and still more preferably 80 to 170 μm from the viewpoints of prevention of bending, regular reflectance, handling properties, and the like. In addition, it is preferable that the center line average roughness (Ra) of the outermost surface layer on the light incident side of the film mirror is 3 nm or more and 20 nm or less from the viewpoint of preventing scattering of reflected light and increasing the light collection efficiency.

Hereinafter, the film mirror of the present invention will be described in detail by dividing into its constituent elements.

[Translucent resin layer]
The translucent resin layer is a layer made of a resin material having optical transparency. This is because sunlight is reflected by the silver reflection layer, and the translucent resin layer positioned thereon needs to be a component through which sunlight passes. Furthermore, since a hard coat layer may be provided on the translucent resin layer, it also has a role of improving adhesion. Moreover, in order to prevent deterioration of the resin base material used as a foundation | substrate, it is preferable that the translucent resin layer contains the ultraviolet absorber.

Although there is no restriction | limiting in particular in the resin material used for a translucent resin layer, The conventionally well-known various synthetic resin which can maintain transparency when forming a thin film can be used. For example, polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, and cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate (CAP), cellulose Cellulose esters such as acetate phthalate and cellulose nitrate or their derivatives, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide, polyether sulfone (PES), polysulfones, polyether ketone imide, polyamide, fluorine Fat, nylon, polymethyl methacrylate, acrylic or polyarylates, and cycloolefin resins such as ARTON (trade name JSR Corp.) or APEL (trade name Mitsui Chemicals, Inc.).

The thickness of the translucent resin layer is preferably 10 to 150 μm. More preferably, it is 15 to 100 μm, and still more preferably 20 to 80 μm. When the film thickness is 10 μm or more, it is possible to sufficiently add materials to be added when providing functions such as protection of the reflection layer, prevention of corrosion, and UV protection, and sufficient adhesion with the adjacent layer is provided. From the viewpoint of bringing about. Setting the thickness to 150 μm or less is preferable from the viewpoint of maintaining the thickness of the entire film mirror moderately and reducing troubles during the winding of manufacturing.

Among the resin materials exemplified above, an acrylic resin can be suitably used as a material for forming the translucent resin layer. Moreover, it is preferable that the translucent resin layer made from an acrylic resin has a methacrylic resin as a main component. The methacrylic resin is a polymer mainly composed of a methacrylic acid ester, and may be a homopolymer of a methacrylic acid ester. The methacrylic acid ester is 50% by mass or more and the other monomer is 50% by mass or less. A copolymer may also be used. Here, as the methacrylic acid ester, an alkyl ester of methacrylic acid is usually used. A particularly preferred methacrylic resin is polymethyl methacrylate resin (PMMA).

The preferred monomer composition of the methacrylic resin is 50 to 100% by weight of methacrylic acid ester, 0 to 50% by weight of acrylic acid ester, and 0 to 49% by weight of other monomers based on the total monomers. More preferably, methacrylic acid ester is 50 to 99.9% by mass, acrylic acid ester is 0 to 50% by mass, and other monomers are 0 to 49% by mass. A particularly preferred combination for the present invention is 75 to 98% by weight of methacrylic acid ester, 0 to 10% by weight of acrylic acid ester, and 1 to 20% by weight of other monomers.

Examples of the alkyl methacrylate include methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and the like. The alkyl group usually has 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms. Of these, methyl methacrylate is preferably used. As commercially available products, acrylic rubber (SRB215, manufactured by Asahi Kasei Chemicals), Delpet (registered trademark) (acrylic resin manufactured by Asahi Kasei Chemicals) and the like may be used.

Examples of alkyl acrylates include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and the like. The alkyl group usually has 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms. is there.

The monomer other than alkyl methacrylate and alkyl acrylate may be a monofunctional monomer, that is, a compound having one polymerizable functional group in the molecule, or a polyfunctional monomer, It may be a compound having at least two polymerizable functional groups in the molecule. Examples of the monofunctional monomer include aromatic alkenyl compounds such as styrene, α-methylstyrene and vinyl toluene, and alkenyl cyan compounds such as acrylonitrile and methacrylonitrile. Examples of polyfunctional monomers include polyunsaturated carboxylic acid esters of polyhydric alcohols such as ethylene glycol dimethacrylate, butanediol dimethacrylate, trimethylolpropane triacrylate, allyl acrylate, allyl methacrylate, and cinnamon. Alkenyl esters of unsaturated carboxylic acids such as allyl acid, polyalkenyl esters of polybasic acids such as diallyl phthalate, diallyl maleate and triallyl cyanurate, diisocyanates such as 1,6-hexamethylene diisocyanate, and divinylbenzene Examples include aromatic polyalkenyl compounds. As for said alkyl methacrylate, alkyl acrylate, and monomers other than these, respectively, you may use those 2 or more types as needed. Of the above, preferred are diisocyanates, and more preferred is 1,6-hexamethylene diisocyanate.

The glass transition temperature of the methacrylic resin is preferably 40 ° C. or higher, more preferably 60 ° C. or higher, from the viewpoint of heat resistance of the film. This glass transition temperature can be appropriately set by adjusting the type of monomer and the ratio thereof.

The methacrylic resin can be prepared by polymerizing the monomer component by a method such as suspension polymerization, emulsion polymerization or bulk polymerization. At that time, in order to obtain a suitable glass transition temperature or to obtain a viscosity showing a formability to a suitable film, it is preferable to use a chain transfer agent during the polymerization. The amount of the chain transfer agent may be appropriately determined according to the type of monomer and the ratio thereof.

(UV absorber)
Although there is no restriction | limiting in particular in the ultraviolet absorber which may be contained in a translucent resin layer, For example, a thiazolidone type, a benzotriazole type, an acrylonitrile type, a benzophenone type, an aminobutadiene type, a triazine type, a phenyl salicylate, a benzoate type etc. Organic ultraviolet absorbers, fine powder type ultraviolet blocking agents such as cerium oxide and magnesium oxide, titanium oxide, zinc oxide, iron oxide and the like, and organic ultraviolet absorbers are particularly preferable.

Examples of organic ultraviolet absorbers include JP-A-46-3335, JP-A-55-15276, JP-A-5-197004, JP-A-5-232630, JP-A-5-307232, JP-A-6-218131, and 8- No. 53427, No. 8-234364, No. 8-239368, No. 9-310667, No. 10-115898, No. 10-147777, No. 10-182621, German Patent No. 19739797A, European Patent Nos. 711804A and JP-A-8-501291, U.S. Pat. Nos. 1,023,859, 2,685,512, 2,739,888, 2,784,087. No. 2,748,021, No. 3,004,896, No. 3,052,636, No. 3,215,530, No. 3,253,9 No. 1, No. 3,533,794, No. 3,692,525, No. 3,705,805, No. 3,707,375, No. 3,738,837, No. The compounds described in 3,754,919, British Patent 1,321,355 and the like can be used.

Among these UV absorbers, UV absorbers having a molecular weight of 400 or more are less likely to volatilize at a high boiling point and are difficult to disperse even during high temperature molding, so that the weather resistance can be effectively improved with a relatively small amount of addition. it can.

In addition, since the ultraviolet absorber having a molecular weight of 400 or more has little transferability from the thin translucent resin layer 6 to other constituent layers and hardly deposits on the surface of the laminate, the amount of contained ultraviolet absorber is small. It is preferable from the viewpoints of being maintained for a long time and being excellent in the durability of the weather resistance improving effect.

Examples of the ultraviolet absorber having a molecular weight of 400 or more include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole, 2,2-methylenebis [4- (1, 1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol], bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis ( Hindered amines such as 1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2-n-butylmalonic acid Bis (1,2,2,6,6-pentamethyl-4-piperidyl), 1- [2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] Such as til] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine A hybrid system having both structures can be mentioned, and these can be used alone or in combination of two or more. Among these, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole and 2,2-methylenebis [4- (1,1,3,3- Tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol] is particularly preferred.

The content of the ultraviolet absorber in the translucent resin layer is preferably 0.1 to 20% by mass, more preferably 1 to 15% by mass, and further preferably 3 to 10% by mass. Further, the content of the ultraviolet absorber in the translucent resin layer 6 is 0.17 to 2.28 g / m ² per unit area of the film, more preferably, the content per unit area is 0.1. 4 to 2.28 g / m ² or more. By setting the content within the above range, it is possible to prevent the roll and the film from being soiled by bleeding out of the ultraviolet absorber while sufficiently exhibiting the weather resistance.

(Antioxidant)
In order to prevent deterioration of the translucent resin layer containing the ultraviolet absorber, the translucent resin layer may contain an antioxidant. As the antioxidant, it is preferable to use a phenol-based antioxidant, a thiol-based antioxidant, or a phosphite-based antioxidant.

In the present invention, the above-mentioned antioxidant and a known light stabilizer can be used in combination. Examples of the light stabilizer include hindered amine light stabilizers.

Examples of a method for forming the light-transmitting resin layer include a method by coating. A resin constituting the translucent resin layer is dissolved or suspended in a suitable organic solvent to prepare a coating solution. Next, the coating solution is applied by a predetermined coating method to form a coating film. When a coating film is applied, various conventionally used coating methods such as spray coating, spin coating, and bar coating can be used.

By these methods, a material that becomes a light-transmitting resin layer is directly applied on the resin base material or on the surface of a layer (for example, a gas barrier layer) provided on the light incident side of the resin base material. Thus, a translucent resin layer can be formed. Then, a coating film is dried and a translucent resin layer is completed.

By forming the translucent resin layer by a coating method, the smoothness of the translucent resin layer can be improved. Specifically, the center line average roughness (Ra) of the translucent resin layer formed by the coating method is preferably 3 nm or more and 20 nm or less. In other words, if the center line average roughness satisfies this value, the translucent resin film produced by melt film formation is not a translucent resin layer provided by bonding with an adhesive layer, but the translucent resin film. It can be considered that the conductive resin layer is provided by coating. The center line average roughness (Ra), which is an index of smoothness of the translucent resin layer, can be determined by a measuring method based on JIS B0601-1982.

[Resin substrate]
The resin base material supports the light reflecting layer that performs the essential function of the film mirror, and has a role of maintaining the mechanical strength of the entire film mirror. Moreover, when manufacturing a film mirror, it is a layer used as the board | substrate for forming another layer. The thickness of the resin base material can be set to an appropriate thickness according to the type and purpose of the resin. For example, it is generally in the range of 10 to 250 μm. The thickness is preferably 15 to 150 μm.

As the resin base material, various conventionally known resin films can be used. For example, cellulose ester film, polyester film, polycarbonate film, polyarylate film, polysulfone (including polyethersulfone) film, polyethylene terephthalate, polyethylene naphthalate polyester film, polyethylene film, polypropylene film, cellophane, Cellulose diacetate film, cellulose triacetate film, cellulose acetate propionate film, cellulose acetate butyrate film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic polystyrene film, polycarbonate film, norbornene resin film , Polymethylpentenef Can Lum, polyether ketone film, polyether ketone imide film, a polyamide film, a fluororesin film, a nylon film, polymethyl methacrylate film, and acrylic films. Among these, polycarbonate films, polyester films such as polyethylene terephthalate, norbornene resin films, cellulose ester films, and acrylic films are preferable. In particular, it is preferable to use a polyester film such as polyethylene terephthalate or an acrylic film, and it may be a film manufactured by melt casting film formation or a film manufactured by solution casting film formation.

[Light reflection layer]
The light reflecting layer is a layer made of metal or the like having a function of reflecting sunlight. The surface reflectance of the light reflection layer is preferably 80% or more, more preferably 90% or more. The light reflecting layer is preferably formed of a material containing any element selected from the element group consisting of Al, Ag, Cr, Cu, Ni, Ti, Mg, Rh, Pt, and Au. Among these, it is preferable that Al or Ag is a main component from the viewpoint of reflectance and corrosion resistance, and two or more such metal thin films may be formed. More preferably, in the present invention, a light reflecting layer mainly containing silver is used. Further, the reflectance may be further improved by providing a layer made of a metal oxide such as SiO ₂ or TiO ₂ in the light reflecting layer.

The thickness of the light reflecting layer is preferably 10 to 200 nm, more preferably 30 to 150 nm, from the viewpoint of reflectivity and the like.

As a method for forming this light reflecting layer, either a wet method or a dry method can be used. The wet method is a general term for a plating method, and is a method of forming a film by depositing a metal from a solution. Specific examples include silver mirror reaction. On the other hand, the dry method is a general term for a vacuum film-forming method. Specific examples include a resistance heating vacuum deposition method, an electron beam heating vacuum deposition method, an ion plating method, and an ion beam assisted vacuum deposition method. And sputtering method. In particular, a vapor deposition method capable of a roll-to-roll method for continuously forming a film is preferably used in the present invention. For example, in the method for manufacturing a film mirror for solar power generation, it is preferable that the light reflecting layer is formed by silver deposition.

When forming the light reflection layer mainly composed of silver, the light reflection layer may be formed by heating and baking a coating film containing a silver complex compound from which a ligand can be vaporized and desorbed. As the formation method by this wet method, for example, those described in paragraphs 0035 to 0056 of WO2013 / 103139 can be used.

[Corrosion prevention layer]
The corrosion prevention layer is a resin layer containing a corrosion inhibitor. In particular, the corrosion prevention layer is preferably adjacent to the light reflection layer from the viewpoint of preventing corrosion of the light reflection layer preferably made of silver, and is provided between the light reflection layer and the protective layer. Is more preferable. That is, from the light incident side, a translucent resin layer, a resin base material, a light reflecting layer, a corrosion prevention layer, a protective layer, and an adhesive layer are more preferably arranged in this order. The corrosion prevention layer may consist of only one layer or may consist of a plurality of layers. In addition, when the corrosion prevention layer is provided on the light incident side of the light reflection layer, the light-transmitting resin layer, the resin base material, the corrosion prevention layer, the light reflection layer, the protective layer, and the adhesive layer are arranged in this order. Arrangement. However, these arrangements are not limited, and the above light-transmitting resin layer may contain a corrosion inhibitor, and the light-transmitting resin layer may also serve as the corrosion preventing layer. The total thickness of the corrosion prevention layer is preferably 1 to 10 μm, more preferably 2 to 8 μm.

Examples of the resin used for forming the corrosion prevention layer include cellulose ester, polyester, polycarbonate, polyarylate, polysulfone (including polyethersulfone), polyester such as polyethylene terephthalate and polyethylene naphthalate, polyethylene, polypropylene, cellophane, and cellulose. Diacetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, polyvinylidene chloride, polyvinyl alcohol, ethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene, polymethylpentene, polyetherketone, polyetherketone Imide, polyamide, fluororesin, nylon, polymethyl methacrylate, acrylic tree And the like can be given. Among these, an acrylic resin is preferable.

The resin material (binder) and the following corrosion inhibitors can be dissolved or dispersed in an organic solvent to prepare a coating solution, and the coating solution can be applied onto the light reflection layer to form a corrosion prevention layer. it can.

(Corrosion inhibitor)
The corrosion inhibitor preferably has an adsorptive group for silver. Here, “corrosion” refers to a phenomenon in which metal (silver) is chemically or electrochemically eroded or deteriorated by the environmental material surrounding it (see JIS Z0103-2004).

The optimum content of the corrosion inhibitor varies depending on the compound to be used, but is generally preferably in the range of 0.1 to 1.0 g / m ² .

Corrosion inhibitors having an adsorptive group for silver include amines and derivatives thereof, compounds having a pyrrole ring, compounds having a triazole ring such as benzotriazole, compounds having a pyrazole ring, compounds having a thiazole ring, and having an imidazole ring It is desirable to be selected from a compound, a compound having an indazole ring, a copper chelate compound, a thiourea, a compound having a mercapto group, a naphthalene-based compound, or a mixture thereof. In compounds such as benzotriazole, the ultraviolet absorber may also serve as a corrosion inhibitor. It is also possible to use a silicone-modified resin. It does not specifically limit as a silicone modified resin. As the corrosion inhibitor, for example, compounds described in paragraphs 0057 to 0062 of WO2013 / 103139 can be used.

[Protective layer]
The present invention is characterized in that a protective layer containing particles and having a thickness of 20 to 75 μm is provided between the light reflecting layer and the adhesive layer. Conventionally, a resin-made film mirror has a problem that the reflectance decreases when it is used by being attached to a light reflecting device. As a result of various studies, the present inventor has found that when the light reflecting layer and the adhesive layer are arranged at a close distance, the adhesive layer has a small elasticity, and therefore the adhesive layer is deformed when attaching a film mirror or due to deterioration over time. As a result, it was found that the light reflecting layer is distorted. It has been found that the reflectance decreases due to the distortion of the light reflecting layer, and furthermore, in the light reflecting device for solar thermal power generation, the light cannot be condensed at a target position, thereby causing a decrease in power generation efficiency. In the present invention, by providing the protective layer having the specific thickness, the distance between the light reflecting layer and the adhesive layer can be increased, the distortion of the light reflecting layer due to the influence of the deformation of the adhesive layer is reduced, and the reflectance Can remain high and constant.

When the thickness of the protective layer is less than 20 μm, the adhesive layer and the light reflecting layer are close to each other, and the adhesive is affected by deformation. Therefore, the effect of preventing distortion of the light reflecting layer and preventing peeling of the layer is not sufficient. On the other hand, if it exceeds 75 μm, the particles added to the protective layer are difficult to come out on the surface, so the adhesion between the adhesive layer and the light reflecting layer is inferior. Further, the protective layer and the layer on the back surface side (for example, a translucent resin layer) with respect to the protective layer of the film mirror are blocked during the manufacturing process, and the outermost layer on the back surface side (for example, the translucent resin layer). ) May be damaged by cutting, which may lead to a decrease in the initial reflectivity. Furthermore, the peeling action between the protective layer and the outermost surface layer due to blocking affects the adhesion between each layer of the film mirror, and by promoting the peeling and deformation of the film mirror, the stability of reflectance over time tends to be lowered. There is a case. The thickness of the translucent protective layer is more preferably 20 to 50 μm, and further preferably 25 to 35 μm. The thickness of the formed protective layer can be known by observing the cross section of the film mirror with an optical microscope of 500 to 1000 times.

Also, by incorporating particles in the protective layer, the surface of the protective layer on the side opposite to the light reflecting layer can be made uneven. By this unevenness, the adhesive layer and the protective layer, which will be described later, mesh with each other, and the adhesion between the adhesive layer and the protective layer can be improved. Therefore, when the film mirror of the present invention is used in a light reflecting device, peeling between the adhesive layer and the protective layer can be prevented even when exposed to the atmosphere for a long time. This is because the surface state of the light reflecting surface is roughened due to peeling between the protective layer and the adhesive layer, and distortion may occur, resulting in a decrease in reflectance. In this way, a decrease in reflectance can be prevented, and the reflectance can be maintained high. It can be known that the surface of the protective layer has irregularities by observing the cross section of the film mirror with an optical microscope of 500 to 1000 times.

(Protective layer forming resin)
Although there is no restriction | limiting in particular in the resin material as a matrix used for a protective layer, The conventionally well-known various synthetic resin which can form a thin film easily with the adhesion layer mentioned later can be used. Use of the same material as the resin for forming the translucent resin layer is advantageous in terms of simplicity of the manufacturing process and cost.

Specific examples of the resin material include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, and cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, and cellulose. Cellulose esters such as acetate propionate (CAP), cellulose acetate phthalate, cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, Polyether ketone, polyimide, polyether sulfone (PES), polysulfones, polyether ketone Bromide, polyamide, fluorine resin, nylon, polymethyl methacrylate, acrylic or polyarylates, and cycloolefin resins such as ARTON (trade name JSR Corp.) or APEL (trade name Mitsui Chemicals, Inc.).

As the material for forming the protective layer, in particular, an acrylic resin can be suitably used. The protective layer made of acrylic resin is preferably mainly composed of methacrylic resin. The methacrylic resin may be a homopolymer of methacrylic acid ester or a copolymer of 50% by mass or more of methacrylic acid ester and 50% by mass or less of other monomers. As the methacrylic acid ester, an alkyl ester of methacrylic acid is usually used. A particularly preferred methacrylic resin is polymethyl methacrylate resin (PMMA). The polymethyl methacrylate resin suitable for the protective layer of the present invention has a weight average molecular weight of 100,000 to 1,000,000, more preferably 200,000 to 400,000.

The weight average molecular weight can be measured by a known method, for example, static light scattering, gel permeation chromatography (GPC), time-of-flight mass spectrometry (TOF-MASS), or the like. In this invention, the value measured by the gel permeation chromatography method which is a general well-known method was employ | adopted.

(particle)
The protective layer of the present invention contains particles in order to make the surface uneven. For the initial effect of preventing delamination between the adhesive layer and the protective layer, the particle size is preferably 5 to 30 μm, more preferably 10 to 20 μm, and the particles have a particle size of 0. The content is preferably 1 to 5.0% by mass, more preferably 0.5 to 2.0% by mass. That is, in one embodiment of the present invention, the film mirror has a particle size of 5 to 30 μm, and the particle is contained in the protective layer in an amount of 0.1 to 5.0% by mass.

If the particle diameter of the particles is 30 μm or less, the adhesiveness and the smoothness of the light reflecting layer are improved, and thus a decrease in reflectance can be prevented. On the other hand, by setting it as 5 micrometers or more, the fall of the adhesiveness by the increase in the distortion of an interlayer can be prevented, and the fall of a reflectance can be prevented. Moreover, if the addition amount of the particle | grains in a protective layer is 0.1 mass% or more, the adhesive improvement effect will be enough and the improvement effect of a distortion will be acquired reliably. On the other hand, if it is 5 mass% or less, it can prevent that the smoothness of a light reflection layer falls. Depending on the matrix of the protective layer and the material of the particles, the size of the irregularities on the surface of the protective layer can be controlled to some extent by changing the particle size and content of the particles.

In the present invention, the particle size of 5 to 30 μm means that 80% by mass or more of the particles contained in the protective layer have a particle size of 5 to 30 μm. The particle diameter is the maximum distance of the particle figure sandwiched between two parallel lines as shown by d in FIG. The particles do not have to be spherical as long as irregularities can be formed on the surface of the protective layer.

In the present invention, as shown in 25 and 27 in FIG. 2, the protective layer has a shape in which particles are added, and the surface has irregularities. The thickness is measured using a Nikon Digimicro MF-501 + counter MFC-101, with both concave and convex portions included, and measured at five points using a 5mmΦ measuring terminal. The value was defined as thickness.

The material of the particle is not particularly limited as long as it can maintain the shape in the protective layer and can provide unevenness on the surface. Particles made of a material that easily disperses in the resin constituting the protective layer and is easily compatible with the material of the adhesive layer can be appropriately selected. Specifically, for example, metal particles such as aluminum and nickel, inorganic oxide particles such as silica, alumina, titania and zirconia, resins such as acrylic resins, polyester resins, urethane resins, polyvinyl acetate resins and nitrile rubbers Particles, diatomaceous earth, talc, zeolite, etc. can be used. These may be used alone or in combination of two or more. Inorganic oxide particles and resin particles are preferable, and acrylic resin particles and silica particles are particularly preferable because of excellent adhesion to the adhesive layer, cost, and weather resistance. That is, one embodiment of the present invention is the film mirror described above, wherein the particles are particles containing acrylic resin or silica. As the acrylic resin particles, polymethyl methacrylate resin particles are particularly preferable. The polymethyl methacrylate resin suitable for the particles in the protective layer of the present invention preferably has a weight average molecular weight of 1000 to 10,000.

In order to form the protective layer, the resin constituting the protective layer is dissolved or suspended in an organic solvent, and the particles are dispersed in this solution to form a coating solution. Next, the coating solution is applied by a predetermined coating method to form a coating film. When a coating film is applied, various conventionally used coating methods such as spray coating, spin coating, and bar coating can be used. Thereafter, the protective layer can be completed by drying.

[Adhesive layer]
The adhesive layer has adhesiveness that enables the film mirror to be attached to the support substrate, and the adhesive layer is used to join the film mirror to the support substrate to form a solar power generation reflection device. It is a constituent layer.

The adhesive layer is not particularly limited, and for example, any of a dry laminating agent, a wet laminating agent, an adhesive, a heat seal agent, a hot melt agent and the like can be used. As the adhesive, for example, a polyester resin, a urethane resin, a polyvinyl acetate resin, an acrylic resin, a nitrile rubber, or the like is used. Among these, acrylic resin is more preferable because it is easily available, is cost effective, and is excellent in weather resistance when a film mirror is used in a light reflecting device. That is, one Embodiment of this invention is said film mirror in which the adhesion layer contains an acrylic resin. The thickness of the pressure-sensitive adhesive layer is usually preferably in the range of about 1 to 100 μm from the viewpoints of the pressure-sensitive adhesive effect, the drying speed, and the like. The laminating method is not particularly limited, and for example, it is preferable to carry out the roll method continuously from the viewpoint of economy and productivity.

Further, the film mirror may include a release sheet that covers the surface of the adhesive layer on the side opposite to the protective layer. When a film mirror has a peeling sheet, after peeling a peeling sheet from an adhesion layer, a film mirror can be affixed on a support base material through an adhesion layer.

(Peeling sheet)
A peeling sheet is a member which covers the surface on the opposite side to the light-incidence side of the adhesion layer in a film mirror. For example, when the film mirror is shipped, the release sheet is attached to the adhesive layer, and then the release sheet is released from the adhesive layer of the film mirror, and the film mirror is attached to the support substrate to reflect the solar power generation reflection device. Can be formed.

The release sheet may be any sheet that can protect the adhesiveness of the adhesive layer. For example, an acrylic film or sheet, a polycarbonate film or sheet, a polyarylate film or sheet, a polyethylene naphthalate film or sheet, a polyethylene terephthalate film Or a plastic film or sheet such as a sheet, a fluorine film, a resin film or sheet kneaded with titanium oxide, silica, aluminum powder, copper powder, etc., or a metal such as aluminum is applied to the resin kneaded with these. A resin film or sheet subjected to surface processing such as vapor deposition is used.

The thickness of the release sheet is not particularly limited but is preferably in the range of 12 to 250 μm.

[Hard coat layer]
The film mirror of the present invention may be provided with a hard coat layer for the purpose of preventing damage to the surface of the film mirror and adhesion of dirt. The transparent hard coat layer is preferably the outermost layer on the light incident side, or the second or third layer from the light incident side. Another thin layer (preferably 1 μm or less) may be provided on the hard coat layer.

Examples of methods for producing the hard coat layer include conventionally known coating methods such as a gravure coating method, a reverse coating method, and a die coating method. In addition to applying and coating a predetermined material, various surface treatments and the like may be combined.

The thickness of the hard coat layer is preferably 0.05 μm or more and 10 μm or less from the viewpoint of preventing the film mirror from warping while obtaining sufficient scratch resistance. More preferably, they are 1 micrometer or more and 10 micrometers or less.

The material for forming the hard coat layer is not particularly limited as long as transparency, weather resistance, hardness, mechanical strength, and the like can be obtained. The hard coat layer can be composed of acrylic resin, urethane resin, melamine resin, epoxy resin, organic silicate compound, silicone resin, and the like. In particular, silicone resins and acrylic resins are preferable in terms of hardness and durability. Furthermore, what consists of an active energy ray hardening-type acrylic resin or a thermosetting type acrylic resin is preferable at the point of sclerosis | hardenability, flexibility, and productivity.

The active energy ray-curable acrylic resin or thermosetting acrylic resin is a composition containing a polyfunctional acrylate, an acrylic oligomer, or a reactive diluent as a polymerization curing component. In addition, you may use what contains a photoinitiator, a photosensitizer, a thermal-polymerization initiator, a modifier, etc. as needed.

Acrylic oligomers include polyester acrylates, urethane acrylates, epoxy acrylates, polyether acrylates, etc., including those in which a reactive acrylic group is bonded to an acrylic resin skeleton, and rigid materials such as melamine and isocyanuric acid. Those having an acrylic group bonded to the skeleton may also be used.

In addition, the reactive diluent has a function of a solvent in the coating process as a medium of the coating agent, and has a group that itself reacts with a monofunctional or polyfunctional acrylic oligomer. It becomes a copolymerization component.

Commercially available polyfunctional acrylic cured paints include Mitsubishi Rayon Co., Ltd. (trade name “Diabeam (registered trademark)” series, etc.), Nagase Sangyo Co., Ltd. (trade name “Denacol (registered trademark)” series, etc. ), Shin-Nakamura Co., Ltd .; (trade name “NK Ester” series, etc.), Dainippon Ink and Chemicals Co., Ltd .; (trade name “UNIDIC (registered trademark)” series, etc.), Toagosei Chemical Industry Co., Ltd .; "Aronix (registered trademark)" series, etc.), Nippon Oil and Fats Corporation; (trade name "Blemmer (registered trademark)" series, etc.), Nippon Kayaku Co., Ltd. (trade name "KAYARAD (registered trademark)" series, etc.), Kyoeisha Chemical Co., Ltd .; (Product name “Light Ester” series, “Light acrylate” series, etc.) Kill.

More specifically, for example, a resin curable by electron beam or ultraviolet irradiation, a thermosetting resin, or the like can be used. In particular, a thermosetting silicone hard coat composed of a partially hydrolyzed oligomer of an alkoxysilane compound, a heat A hard coat made of a curable polysiloxane resin, an ultraviolet curable acrylic hard coat made of an acrylic compound having an unsaturated group, and a thermosetting inorganic material are preferable. As materials that can be used for the hard coat layer, an aqueous colloidal silica-containing acrylic resin (Japanese Patent Laid-Open No. 2005-66824), a polyurethane-based resin composition (Japanese Patent Laid-Open No. 2005-110918), and an aqueous silicone compound as a binder. Resin film used (Japanese Patent Laid-Open No. 2004-142161), photocatalytic oxide-containing silica film such as titanium oxide or alumina, photocatalytic film such as titanium oxide or niobium oxide having a high aspect ratio (Japanese Patent Laid-Open No. 2009-62216), photocatalyst Examples thereof include a fluorine-containing resin coating (Pierex Technologies), an organic / inorganic polysilazane film, and a film using a hydrophilization accelerator (AZ Electronics) in organic / inorganic polysilazane.

For the thermosetting silicone hard coat layer, a partially hydrolyzed oligomer of an alkoxysilane compound synthesized by a known method can be used. An example of the synthesis method is as follows. First, tetramethoxysilane or tetraethoxysilane is used as an alkoxysilane compound, and a predetermined amount of water is added to the alkoxysilane compound in the presence of an acid catalyst such as hydrochloric acid or nitric acid to remove by-produced alcohol from room temperature to 80 ° C. React with. By this reaction, the alkoxysilane is hydrolyzed, and further, a partially hydrolyzed oligomer of the alkoxysilane compound having an average polymerization degree of 4 to 8 having two or more silanol groups or alkoxy groups in one molecule is obtained by the condensation reaction. Next, a curing catalyst such as acetic acid or maleic acid is added to this and dissolved in an alcohol or glycol ether organic solvent to obtain a thermosetting silicone hard coat liquid. And this is apply | coated to the outer surface of a film mirror etc. by the coating method in a normal coating material, and a transparent hard-coat layer is formed by heat-hardening at the temperature of 80-140 degreeC. However, in this case, the setting of the curing temperature below the thermal deformation temperature of the film mirror is a prerequisite. In addition, by using di (alkyl or aryl) dialkoxysilane and / or mono (alkyl or aryl) trialkoxysilane instead of tetraalkoxysilane, a polysiloxane-based transparent hard coat layer is similarly produced. Is possible.

(Additive)
The hard coat layer may contain an ultraviolet absorber or an antioxidant. As an ultraviolet absorber and antioxidant, the ultraviolet absorber and antioxidant used with the above-mentioned translucent resin layer can be used.

In particular, a preferred UV absorber in a hard coat layer containing a polyfunctional acrylic monomer and a silicone resin is a benzotriazole UV absorber. By including a benzotriazole-based ultraviolet absorber in the hard coat layer, it is possible to obtain an excellent effect that not only the weather resistance is further improved, but also the falling angle can be further reduced. In particular, when the compound represented by the following general formula (9) is contained in the hard coat layer, the effect of reducing the falling angle is remarkable. The falling angle refers to a value obtained by dropping a water drop on a horizontal mirror and then gradually increasing the tilt angle of the mirror, and measuring the minimum angle at which the water drop of a predetermined mass that has been stationary falls. Say. It can be said that the smaller the tumbling angle, the easier the water droplets to roll off the surface, and the surface to which the water droplets hardly adhere.

The amount of the UV absorber used in the hard coat layer is preferably 0.1 to 20% by mass in order to improve the weather resistance while maintaining good adhesion. More preferably, it is 0.25 to 15% by mass, and more preferably 0.5 to 10% by mass.

As the antioxidant used in the hard coat layer, it is preferable to use an organic antioxidant such as a phenol-based antioxidant, a thiol-based antioxidant, and a phosphite-based antioxidant. The falling angle can also be reduced by including an organic antioxidant in the hard coat layer. An antioxidant and a light stabilizer may be used in combination. As the light stabilizer, the same light stabilizer as that used in the above-described translucent resin layer can be used.

In the hard coat layer, various additives can be further blended as necessary. For example, a surfactant, a leveling agent and an antistatic agent can be used. The leveling agent is effective in reducing surface irregularities. As the leveling agent, for example, a dimethylpolysiloxane-polyoxyalkylene copolymer (for example, SH190 manufactured by Toray Dow Corning Co., Ltd.) is suitable as the silicone leveling agent.

[Gas barrier layer]
The gas barrier layer is preferably provided on the light incident side of the light reflecting layer, and is effective for preventing corrosion of the light reflecting layer. The gas barrier layer is intended to prevent the deterioration of the humidity, particularly the deterioration of the resin base material and each component layer supported by the resin base material due to high humidity, but it has special functions and applications. As long as it has a deterioration preventing function, various types of gas barrier layers can be provided.

As the moisture resistance of the gas barrier layer, the water vapor permeability at 40 ° C. and 90% RH is preferably 1 g / m ² · day or less, more preferably 0.5 g / m ² · day or less, and still more preferably 0. .2 g / m ² · day or less. In addition, the oxygen permeability of the gas barrier layer is preferably 0.6 ml / m ² / day / atm or less under the conditions of a measurement temperature of 23 ° C. and a humidity of 90% RH.

Examples of the method for forming the gas barrier layer include a method of forming an inorganic oxide by a method such as vacuum vapor deposition, sputtering, ion beam assist, chemical vapor deposition, and the like. An inorganic oxide precursor by a sol-gel method is used. A method of forming an inorganic oxide film by applying heat treatment and / or ultraviolet irradiation treatment to the coating film after coating is also preferably used.

[Anchor layer]
The film mirror of this invention may provide an anchor layer between the resin base material and the light reflection layer. The anchor layer is made of resin, and has an effect of closely adhering the resin base material and the light reflecting layer. Therefore, the anchor layer has an adhesion property that allows the resin base material and the light reflection layer to adhere to each other, heat resistance that can withstand heat when the light reflection layer is formed by a vacuum deposition method, and the high reflection that the light reflection layer originally has. Smoothness is required to bring out performance.

The resin material used for the anchor layer is not particularly limited as long as it satisfies the above conditions of adhesiveness, heat resistance, and smoothness. Polyester resin, acrylic resin, melamine resin, epoxy resin, polyamide Resin, vinyl chloride resin, vinyl chloride vinyl acetate copolymer resin or the like, or a mixed resin thereof can be used. From the viewpoint of weather resistance, a polyester resin and a melamine resin mixed resin are preferable. It is more preferable to use a thermosetting resin mixed with a curing agent.

As a method for forming the anchor layer, conventionally known coating methods such as a gravure coating method in which a predetermined resin material is applied and applied, a reverse coating method, a die coating method and the like can be used.

The thickness of the anchor layer is preferably 0.01 to 3 μm, more preferably 0.1 to 1 μm. If thickness is 0.01 micrometer or more, the effect of an adhesive improvement will be acquired reliably, and since the unevenness | corrugation on the surface of a resin base material can also be covered, smoothness will also be improved. As a result, the reflectance of the light reflecting layer is preferably increased. Moreover, if thickness is 3 micrometers or less, it is enough for the improvement of adhesiveness, it can avoid that smoothness worsens by generation | occurrence | production of a coating nonuniformity, and also hardening of an anchor layer becomes sufficient.

[Light Reflector]
The film mirror of the present invention is suitable for use in a light reflecting device by sticking to a support substrate. Therefore, this invention also provides the light reflection apparatus for solar power generation which affixed said film mirror on the support base material. One embodiment of the present invention is a light reflecting device for solar power generation in which the film mirror is attached to a support base material. The solar power generation reflecting device is a reflecting mirror that includes a film mirror and a self-supporting support base material, and the film mirror is bonded to the support base material via an adhesive layer.

In addition, the "self-supporting property" as used herein means that the supporting substrate supports the edge portion of the film mirror in a state where the supporting substrate is cut to a size used as a supporting substrate of the solar power generation reflecting device. This means that the film mirror has rigidity enough to support the film mirror. The support base material of the solar power generation reflecting device has self-supporting properties, so that it is easy to handle when installing the solar power generation reflecting device, and the holding member for holding the solar power generation reflecting device has a simple configuration. Therefore, it is possible to reduce the weight of the reflection device itself, and it is possible to suppress power consumption during solar tracking.

(Supporting substrate)
As a self-supporting support base material, there are one having a pair of metal flat plates and an intermediate layer interposed between the metal flat plates (type A), or one made of a resin material having a hollow structure (type B). It is preferable.

(Support base type A)
The support base material has a pair of metal flat plates and an intermediate layer interposed between the metal flat plates, and the intermediate layer is made of a material having a hollow structure or a resin material, whereby the support base material As well as having a high flatness due to the metal flat plate, it is possible to significantly reduce the weight of the support base material itself as compared to the case where the support base material is constituted only by the metal flat plate. In addition, since the rigidity can be increased by the metal flat plate while using a relatively lightweight intermediate layer, it is possible to function as a support substrate that is lightweight and has a self-supporting property.

Furthermore, even when the intermediate layer is made of a resin material, further weight reduction can be achieved by using a resin material layer having a hollow structure.

Further, when the intermediate layer has a hollow structure, the intermediate layer functions as a heat insulating material, so that the temperature change of the metal flat plate on the side opposite to the adhesive layer 8 is suppressed from being transmitted to the film mirror, and dew condensation occurs. It is possible to prevent or suppress deterioration due to heat.

As the metal flat plate that becomes the surface layer on both sides of the support substrate, the thermal conductivity such as steel plate, copper plate, aluminum plate, aluminum plated steel plate, aluminum alloy plated steel plate, copper plated steel plate, tin plated steel plate, chrome plated steel plate, stainless steel plate, etc. A high metal material can be preferably used. In the present invention, it is particularly preferable to use a plated steel plate, a stainless steel plate, an aluminum plate or the like having good corrosion resistance.

As the intermediate layer of the supporting substrate, materials such as metals, inorganic materials (glass, etc.), resin materials, etc. can be used.

When this intermediate layer has a hollow structure, a cellular structure made of foamed resin, a three-dimensional structure having a wall surface made of metal, an inorganic material or a resin material (honeycomb structure, etc.), a resin material to which hollow fine particles are added, etc. are applied. be able to.

The cellular structure of the foamed resin refers to a foamed or porous shape formed by finely dispersing gas in the resin material. A known foamed resin material can be used as the material, but polyolefin resin, polyurethane, polyethylene, polystyrene and the like are preferably used.

The honeycomb structure represents a general three-dimensional structure composed of a plurality of small spaces surrounded by side walls.

When the intermediate layer has a three-dimensional structure having a wall surface made of a resin material, the resin material constituting the wall surface is a homopolymer or copolymer of olefins such as ethylene, propylene, butene, isoprene pentene, and methylpentene. Polyolefin (eg, polypropylene, high density polyethylene), polyamide, polystyrene, polyvinyl chloride, polyacrylonitrile, acrylic derivatives such as ethylene-ethyl acrylate copolymer, polycarbonate, vinyl acetate such as ethylene-vinyl acetate copolymer Copolymers, ionomers, terpolymers such as ethylene-propylene-dienes, and thermoplastic resins such as ABS resin, polyolefin oxide, and polyacetal are preferably used. In addition, these may be used individually by 1 type, or may mix and use 2 or more types. In particular, among thermoplastic resins, olefin-based resins or resins mainly composed of olefin-based resins, polypropylene-based resins or resins based mainly on polypropylene-based resins are preferable because of excellent balance between mechanical strength and moldability. . The resin material may contain an additive. Examples of the additive include silica, mica, talc, calcium carbonate, glass fiber, carbon fiber, and other inorganic fillers, plasticizers, stabilizers, colorants, charging agents. An inhibitor, a flame retardant, a foaming agent, etc. are mentioned.

Further, the intermediate layer can be a layer made of a resin plate. In this case, as the resin material constituting the intermediate layer, the same material as that constituting the resin substrate of the film mirror described above is preferably used. be able to.

The intermediate layer need not be provided in all regions of the support base material, and provided in a part of the region as long as the flatness of the metal flat plate and the self-supporting property as the support base material can be ensured. May be. When the intermediate layer has the above-described three-dimensional structure, it is preferable to provide the three-dimensional structure in a region of about 90 to 95% with respect to the area of the metal flat plate. It is preferable to provide it.

(Supporting substrate type B)
It is also possible for the support substrate to be a layer made of a resin material having a hollow structure. When the support base material is made of a resin material only, the thickness required to obtain a rigidity sufficient to provide self-supporting properties increases, resulting in an increase in the weight of the support base material. By providing a hollow structure, the supporting substrate can be reduced in weight while providing self-supporting properties.

When the support substrate is made of a resin material having a hollow structure, it is possible to use a resin material having a hollow structure as an intermediate layer, and to provide a resin sheet having smooth surfaces as the surface layers on both sides thereof. It is preferable from the viewpoint of increasing the rate. As the material of the resin sheet, the same material as that constituting the resin substrate of the film mirror described above can be preferably used. As the resin material having a hollow structure, the above-described foamed material and the resin material having a three-dimensional structure (honeycomb structure) can be preferably used.

(Holding member)
The solar power generation reflection device has a holding member that holds the reflection device itself. The holding member preferably holds the reflecting surface (film mirror) of the solar power generation reflecting device in a state where the sun can be tracked. The form of the holding member is not particularly limited, but for example, a plurality of places on the support base on the back side of the solar power generation reflecting device are formed in a bar shape so that the solar power generating reflection device can hold a desired shape and posture. The form held by a columnar member or a beam-like member is preferable.

The holding member has a configuration for holding the solar power generation reflecting device in a state in which the sun can be tracked. However, in the case of solar tracking, the holding member may be driven manually, or a separate driving device may be provided to automatically track the sun. It is good also as composition to do.

Hereinafter, the present invention will be described through examples and comparative examples. However, the present invention is not limited to the following examples.

<Example 1>
A resin film which is a biaxially stretched polyester film (polyethylene terephthalate film thickness 25 μm) was used as the resin substrate. On one surface of the polyethylene terephthalate film, polymethylmethacrylic (PMMA) resin (EMB457 manufactured by Mitsubishi Rayon), acrylic rubber (SRB215 Asahi Kasei Chemicals), HDMI isocyanate (1,6-hexamethylene diisocyanate) in a resin solid content ratio, The mixture was mixed into methyl ethyl ketone at 17: 3: 2 so that the solid content concentration was 22%. This solution was coated by an applicator bar coater method to form a translucent resin layer having a thickness of 25 μm.

Next, a light reflecting layer made of silver having a thickness of 100 nm was formed on the opposite surface of the supporting substrate by vacuum deposition.

Next, a silver corrosion inhibitor is applied to a resin in which a polyester resin and a TDI (2.4-tolylene diisocyanate) isocyanate are mixed at a resin solid content ratio of 10: 2 on the silver light reflection layer. As described above, 2-mercaptobenzothiazole was added so as to be 10% by mass with respect to the resin, and a coating solution was prepared so as to be 5% in methyl ethyl ketone. This coating solution was coated on the light reflection layer by a gravure coating method to form a corrosion prevention layer having a thickness of 3 μm.

Next, on the corrosion prevention layer, PMMA resin (EMB457, manufactured by Mitsubishi Rayon), acrylic rubber (SRB215, Asahi Kasei Chemicals), HDMI-based isocyanate (1,6-hexamethylene diisocyanate), PMMA filler (manufactured by Soken Chemical Co., Ltd., MX1500, particle size 15 μm) ) At a resin solid content ratio of 17: 3: 2: 0.11 and mixed in methyl ethyl ketone so as to have a solid content concentration of 22% to prepare a coating solution. This coating solution was coated by an applicator bar coater method to form a protective layer having a thickness of 20 μm.

Next, acrylic pressure-sensitive adhesive (Nissetsu KP-2254, manufactured by Nippon Carbide Industries) and HDMI-based isocyanate (1,6-hexamethylene diisocyanate) are in a resin solid content ratio of 27: 1 so that the solid content concentration is 15%. The mixture was mixed with ethyl acetate to prepare a coating solution. This coating solution was coated on the protective layer by an applicator bar coater method to form an adhesive layer having a thickness of 25 μm.

The film mirror of Example 1 was obtained as described above. The obtained film mirror evaluated the following light reflection layer distortion | strain, the interlayer adhesiveness of a protective layer and an adhesion layer, and blocking with a translucent resin and a protective layer. The evaluation results are shown in Tables 1-1 and 1-2 below.

<Interlayer adhesion>
The film mirror sample was cut to a width of 10 mm, the adhesive layer was attached to a glass plate, and the adhesive strength was measured after irradiation with a metal hold lamp 500 hr. The adhesive strength before and after the metal halide lamp irradiation (based on JIS Z0237 (2009)) was compared. The evaluation criteria were as follows.
5: No peeling was observed at the interface between the protective layer and the adhesive layer, and the adhesive strength was 120% or more of the initial value.
4: There is almost no sign of peeling at the interface between the protective layer and the adhesive layer, and the adhesive strength is 100% to less than 120% of the initial value.
3: Although slight signs of peeling are observed between the protective layer and the adhesive layer, the adhesive strength is less than 80 to 100% of the initial value.
2: Slight peeling was observed between the protective layer and the adhesive layer, and the adhesive strength was less than 50 to 80% of the initial value.
1: Clear peeling is observed at the interface between the protective layer and the adhesive layer, and the adhesive strength is less than 50% of the initial value.

<Blocking>
In the manufacturing process, it may be wound in a state where the translucent resin layer and the protective layer are in contact with each other, and if both layers are adhered at that time, there is a concern that the surfaces of both layers become rough and cause a decrease in reflectance. is there. Therefore, it is preferable that blocking does not occur. For the evaluation of blocking, a film mirror sample was cut out to 10 cm × 10 cm, the translucent resin layer and the protective layer were overlapped, and a load of 7 g / cm ² was applied at 23 ° C. for 72 hours. Then, the blocking state at the time of peeling off a protective layer was confirmed. The evaluation criteria were as follows.
5: No peeling at all and no peeling of the layer.
4: Although it feels wet as a surface, there is no sound and the peeling layer does not peel off.
3: There is a feeling that the surface is wet, but there is no peeling part.
2: It has adhered partially and a translucent resin layer peels off.
1: It has adhered to the whole surface and a translucent resin layer peels off.

<Measurement of regular reflectance>
A spectrophotometer “UH4150” manufactured by Hitachi High-Tech was used to adjust the incident angle of incident light to 5 ° with respect to the normal of the reflecting surface, and the regular reflectance at a reflection angle of 5 ° was measured. Evaluation was carried out as an average reflectance of 250 nm to 2500 nm.

<Reflectance after weather resistance test of regular reflectance>
The regular reflectance after standing for 30 days under the conditions of a temperature of 85 ° C. and a humidity of 85% RH was measured by the same method as the regular reflectance measurement.

<Examples 2 to 9>
A film mirror was produced in the same manner as in Example 1 except that the thickness of the protective layer to be formed and the kind of particles were changed as shown in Table 1-1 below. The obtained film mirror was evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 1-1 and 1-3 below.

<Comparative Examples 1 to 4>
A film mirror was produced in the same manner as in Example 1, except that the thickness of the protective layer to be formed and the kind of particles were changed as shown in Table 1-2 below. The obtained film mirror was evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 1-2 and 1-3 below.

From the results shown in Table 1, it was found that the film mirror of the present invention was provided with a protective layer, whereby the distortion of the light reflection layer was reduced and the reflectance after the weather resistance test was maintained high. Furthermore, the mirror of the present invention also showed good results in interlayer adhesion and blocking properties between the protective layer and the adhesive layer due to the presence of particles in the protective layer. These results are apparent when compared with Comparative Example 3 having no protective layer. Further, when Example 1 is compared with Comparative Example 1 having a thin protective layer, Example 1 shows a more excellent result in the reflectance after the initial and weather resistance tests, and in the interlayer adhesion between the protective layer and the adhesive layer. showed that. Further, when Example 1 was compared with Comparative Example 2 having a thick protective layer, Comparative Example 2 resulted in a decrease in reflectance after the weather resistance test and inferior blocking properties.

Note that this application is based on Japanese Patent Application No. 2013-224556 filed on October 29, 2013, the disclosure of which is incorporated by reference in its entirety.

10, 20 Film mirror,
11, 21 Translucent resin layer,
12, 22 resin base material,
13, 23 Light reflection layer,
14, 24 Anticorrosion layer,
15, 25 protective layer,
16, 26 Adhesive layer,
17, 27 particles,
28 Hard coat layer,
30 Anchor layer.

Claims

From the light incident side
A translucent resin layer;
A resin substrate;
A light reflecting layer;
A protective layer containing particles and having a thickness of 20 to 75 μm;
An adhesive layer in contact with the protective layer;
A film mirror equipped with in order.
2. The film mirror according to claim 1, wherein the particle diameter is 5 to 30 μm, and the particle is contained in the protective layer in an amount of 0.1 to 5.0 mass%.
The film mirror according to claim 1 or 2, wherein the particles are particles containing acrylic resin or silica.
The film mirror according to any one of claims 1 to 3, wherein the adhesive layer contains an acrylic resin.
A light reflecting device for solar power generation, wherein the film mirror according to any one of claims 1 to 4 is attached to a supporting substrate.