JP2016200781A - Light reflecting film, and light reflecting body and sunlight reflecting device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light reflecting film which has good initial light condensing efficiency, and has improved reduction in light condensing efficiency in outdoor environment with a lapse of time, occurrence of cracks and reduction in adhesiveness.SOLUTION: A light reflecting film has at least one resin base material, a hard coat layer, an ultraviolet absorbing layer and a light reflecting layer, has the hard coat layer, the ultraviolet absorbing layer and the light reflecting layer arranged in this order, and has an image clarity (DOI) value measured from the side opposite to the ultraviolet absorbing layer of the hard coat layer according to ASTM D5767-95(2012) of 97.0-100.0.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light reflecting film, a light reflector having the light reflecting film, and a sunlight reflecting device. More specifically, the present invention relates to a technique for improving the initial light collection efficiency of a light reflecting film and improving the deterioration of light collection efficiency, cracking, and adhesion due to aging in an outdoor environment. .

  In recent years, power generation technologies using natural energy such as sunlight, wind power, and geothermal heat have been developed as alternative energy for fossil fuels. Among these, sunlight is particularly attracting attention because of its stability and abundant energy.

  On the other hand, sunlight has a property that energy density is low and it is difficult to store and transfer energy. Therefore, research and development of technologies for converting sunlight into electric energy (solar thermal power generation, solar cells) are being actively conducted.

  Solar thermal power generation is a power generation method that collects sunlight and uses it as a heat source. Compared with solar cells, solar thermal power generation has the advantages of being able to generate electricity day and night by storing heat and the cost of manufacturing and maintenance being low. From a long-term perspective, solar power generation is more powerful than solar cells. It is considered highly efficient. Therefore, plans are underway to build solar power generation facilities in desert areas with good sunshine conditions throughout the year.

  In solar thermal power generation, a condensing device (sunlight reflecting device) that reflects sunlight by a light reflector (mirror) and condenses it in one place is used. Since the said light reflector is exposed to the ultraviolet-ray by sunlight, a heat | fever, a wind and rain, a sandstorm, etc., conventionally the glass-made light reflector has been used from a durable viewpoint. However, the glass light reflector has problems such as being heavy, large in volume, expensive in transportation, difficult to install, and easy to break.

  In order to solve the above problem, a light reflector in which a resin light reflection film including a metal reflection layer of silver or the like as a light reflection layer is attached to a support substrate has been proposed. For example, Patent Document 1 discloses a film having a metal reflective layer and an ultraviolet absorbing layer containing a triazine compound having a specific structure in this order on a resin support, and further having a hard coat layer on the outermost surface. A mirror is disclosed. And according to such a film mirror, it is supposed that the adhesiveness of a support body and a metal reflective layer and a weather resistance can be improved.

JP 2014-199330 A

  However, the film mirror described in Patent Document 1 has a low ultraviolet-ray absorption layer and has a high ultraviolet absorption effect. The problem is that peeling of the constituent layers occurs.

  Therefore, the present invention has an object to provide a light reflecting film that has good initial light collection efficiency and improved reduction in light collection efficiency, cracking, and adhesion due to aging in an outdoor environment. And

  The problems of the present invention are solved by the following configurations.

  It has at least one resin base material, a hard coat layer, an ultraviolet absorption layer, and a light reflection layer, and the hard coat layer, the ultraviolet absorption layer, and the light reflection layer are arranged in this order, In addition, in a method according to ASTM D5767-95 (2012), the image clarity (DOI) value measured from the side opposite to the ultraviolet absorbing layer of the hard coat layer is 97.0 to 100.0. Reflective film.

  ADVANTAGE OF THE INVENTION According to this invention, the initial condensing efficiency is favorable and the light reflection film with which the fall of the condensing efficiency by the passage of time in outdoor environment, the generation | occurrence | production of a crack, and the adhesive fall was improved is provided.

It is a schematic sectional drawing which shows an example of preferable embodiment of a structure of the light reflection film of this invention. It is a schematic sectional drawing which shows an example of other preferable embodiment of the structure of the light reflection film of this invention.

  Embodiments of the present invention will be described below. In addition, this invention is not limited only to the following embodiment. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

  In this specification, “X to Y” indicating a range means “X or more and Y or less”. Unless otherwise specified, measurement of operation and physical properties is performed under conditions of room temperature (20 to 25 ° C.) / Relative humidity 40 to 50%.

  Furthermore, in the present specification, the notation “(meth) acryl” in the specific names of the compounds represents “acryl” and “methacryl”, and “(meth) acrylate” represents “acrylate” and “methacrylate”. The term “acrylic resin” means a (co) polymer of acrylic acid ester and / or methacrylic acid ester.

<Light reflection film>
One embodiment of the present invention includes at least one resin base material, a hard coat layer, an ultraviolet absorption layer, and a light reflection layer, and the hard coat layer, the ultraviolet absorption layer, and the light reflection layer Are arranged in this order, and the image clarity (DOI) value measured from the side opposite to the ultraviolet absorbing layer of the hard coat layer is 97.0 in a method according to ASTM D5767-95 (2012). It is related with the light reflection film which is 100.0. According to the light reflecting film according to one embodiment of the present invention having such a configuration, the initial light collection efficiency is good. In addition, it is possible to suppress a decrease in light collection efficiency, generation of cracks, and a decrease in adhesiveness over time in an outdoor environment exposed to ultraviolet rays, heat, wind and rain, and sandstorms caused by sunlight.

  Here, the light reflecting film according to an aspect of the present invention is such that another constituent member is disposed on each constituent member (layer and resin base material) and at an arbitrary position between them. Alternatively, the constituent members may be adjacent to each other.

  As a result of intensive studies, the inventors of the present invention have measured the light reflecting film having the above configuration from the side opposite to the ultraviolet absorbing layer of the hard coat layer by a method based on ASTM D5767-95 (2012). By setting the image clarity (DOI) value to 97.0 to 100.0, the initial light collection efficiency is improved, reducing the light collection efficiency over time in the outdoor environment, generating cracks, and reducing the adhesion. It was found that it can be suppressed.

  The present inventors presume the mechanism by which the above-described problems can be solved by adopting the configuration of the present invention as follows.

  Also in the conventional light reflecting film, the fine surface roughness of each constituent layer such as the light reflecting layer and the substrate, which is measured using an atomic force microscope (AFM), has been mainly discussed. Such surface roughness is on the order of several nanometers to several tens of nanometers. However, such surface roughness has been confirmed to have a clear correlation with the weather resistance of the light-reflecting film, particularly with the degree of light collection efficiency, cracking, and adhesiveness deterioration over time in the outdoor environment. There wasn't.

  However, the film surface includes irregularities on the film surface of a larger order that cannot be expressed as fine surface roughness, such as waviness of the film thickness. Since the unevenness of the film surface is caused by unintended deformation of the film, the frequency and degree thereof and the magnitude of the residual stress in the film are related. When the light reflecting film is aged in a high temperature and / or high humidity environment such as an outdoor environment, the deformation of the light reflecting film proceeds due to such residual stress. And, due to such deformation, the light collection efficiency over time in the outdoor environment decreases. Such deformation also causes cracking and peeling of the constituent layers within the film.

  Further, since the image clarity represents the sharpness of the object image, the image clarity is related to the surface shape of the film. The surface roughness on the order of several nanometers to several tens of nanometers has little influence on the image clarity, but the unevenness of the film surface having a larger order has a great influence on the image clarity. Here, the closer the image clarity (DOI) value is to 100.0, the lower the frequency of irregularities on the film surface and the smaller the irregularities on the film surface. Accordingly, as the value of the image clarity (DOI) value is closer to 100.0, the light reflecting film, in particular, the light reflecting layer has a uniform surface shape, so that the initial light collection efficiency is increased. In addition, the closer the image clarity (DOI) value is to 100.0, the smaller the residual stress in the film. Therefore, the deformation of the light reflecting film caused by the residual stress over time in the outdoor environment is also reduced, and the light is condensed. Efficiency is reduced, cracks are generated, and adhesion is suppressed.

  Note that the above mechanism is based on speculation, and its correctness does not affect the technical scope of the present invention.

  Hereinafter, the structure of the whole light reflection film of this form is demonstrated, referring 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 schematic cross-sectional view showing a light reflecting film according to a preferred embodiment of the present invention. 1 includes a hard coat layer 11, an ultraviolet absorbing layer 12, a resin base material 14, an anchor layer 16, a light reflection layer 13, a corrosion prevention layer 17, an adhesive layer 15, and a resin base material 18 in this order. Is laminated.

  FIG. 2 is a schematic cross-sectional view showing an example of another preferred embodiment of the configuration of the light reflecting film of the present invention. The light reflecting film 10 is formed by laminating a hard coat layer 11, an ultraviolet absorbing layer 12, a corrosion preventing layer 17, a light reflecting layer 13, an anchor layer 16 and a resin base material 14 in this order.

  1 and 2, any one of the hard coat layer 11, the ultraviolet absorbing layer 12, the light reflecting layer 13, and the resin base material 14 or 18 is an essential constituent member in the present invention. Further, the other layers are constituent members that can optionally be included.

  Here, the light reflecting film according to an embodiment of the present invention is such that other constituent members are arranged on each constituent member (layer and resin base material) and at any position between them. Alternatively, the constituent members may be adjacent to each other.

  About these each structural member, detailed description is mentioned later for every structural member.

  The image clarity (DOI) value of the light reflecting film is 97.0 to 100.0. When the image clarity (DOI) value is less than 97.0, the initial light collection efficiency of the light reflecting film is lowered, and the reduction of the light collection efficiency with the passage of time in the outdoor environment is increased. Furthermore, in the light reflecting film, the occurrence frequency of cracks with the passage of time in the outdoor environment is high, and the occurrence frequency of peeling of the constituent layers in the film is increased. From the same viewpoint, the image reflectivity (DOI) value of the light reflecting film is preferably 97.2 to 100.0, more preferably 97.4 to 100.0, and 97.5 to 100. More preferably, it is 0.

  The image clarity (DOI) value of the light reflecting film can be measured by a method based on ASTM D5767-95 (2012). As the image clarity (DOI) value of the light reflecting film, a value measured from the side opposite to the ultraviolet absorbing layer of the hard coat layer of the light reflecting film is used. Here, the side of the hard coat layer opposite to the ultraviolet absorbing layer is the side where the ultraviolet absorbing layer of the hard coat layer exists when the hard coat layer, the ultraviolet absorbing layer, and the light reflecting layer are arranged in this order. Represents the opposite side. As the image clarity (DOI) value of the light reflection film, a value measured using RHOPOINT IQ manufactured by RHOPOINT is adopted.

  The image clarity (DOI) value is the thickness of the base material, the thickness of each layer, the type and ratio of materials for forming each layer, the configuration of the light reflecting film, the coating conditions for forming each constituent layer, and the drying conditions. It can be controlled by the winding tension at the time of winding the light reflecting film. Here, with regard to the configuration of the film, for example, the image clarity (DOI) value can be reduced by reducing the thickness of the ultraviolet absorbing layer or reducing the thickness of the adhesive layer. Regarding film production conditions, the image clarity (DOI) value can be reduced, for example, by reducing the winding tension during winding of the light reflecting film. In addition, when a layer directly formed on the surface of the light reflecting layer is produced using a method by coating, for example, by increasing the drying temperature after coating, the image clarity (DOI) value can be decreased. it can.

  The total thickness of the light reflecting film of the present invention is not particularly limited, but is preferably 20 to 300 μm, more preferably 30 to 200 μm, and still more preferably 50 to 170 μm from the viewpoints of prevention of bending, regular reflectance, handling properties, and the like. is there.

  Hereinafter, each component of the light reflecting film will be described in detail.

[Hard coat layer]
The light reflecting film of this embodiment essentially includes a hard coat layer. The hard coat layer is preferably disposed as the outermost layer on the light incident side.

  In the present specification, the “hard coat layer” means a layer having a pencil hardness of H or more according to JIS K 5600-5-4: 1999 (ISO / DIS 15184: 1996). The hard coat layer functions as a surface protective layer for enhancing the scratch resistance of the light reflecting film.

  As a hard coat material constituting the hard coat layer according to the present invention, an inorganic material typified by polysiloxane, an ultraviolet curable resin, or the like can be used.

Polysiloxane Hard Coat Material The polysiloxane hard coat material applicable to the formation of the hard coat layer according to the present embodiment can use, for example, a compound represented by the following general formula (1) as a starting material.

General formula (1)
(R) _m Si (OR ₁ ) _n
In the general formula (1), R and R ₁ each represent an alkyl group having 1 to 10 carbon atoms, and m and n are integers satisfying a relationship of m + n = 4.

  Specific compounds include tetramethoxysilane, tetraethoxysilane, tetra-iso-propoxysilane, tetra-n-popropoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane, tera Pentaethoxysilane, tetrapenta-iso-propoxysilane, tetrapenta-n-propoxysilane, tetrapenta-n-butoxysilane, tetrapenta-sec-butoxysilane, tetrapenta-tert-butoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyl Tributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethylethoxysilane, dimethylmethoxysilane, dimethylpropoxysilane, dimethylbutoxy Emissions, dimethyldimethoxysilane, dimethyldiethoxysilane, hexyl trimethoxysilane. In addition, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-β- ( N-aminobenzylaminoethyl) -γ-aminopropylmethoxysilane / hydrochloride, γ-glycidoxypropyltrimethoxysilane, aminosilane, methylmethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloro Mention may be made of propyltrilimethoxysilane, hexamethyldisilazane, vinyltris (β-methoxyethoxy) silane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride. Those having a hydrolyzable group such as methoxy group or ethoxy group substituted with a hydroxy group are generally referred to as polyorganosiloxane hard coat materials.

  Specific examples of the polyorganosiloxane-based hard coat material include Sarkote (trademark) B16N and other Sarkote series (manufactured by Doken Co., Ltd.), SR2441 (manufactured by Dow Corning Toray), Perma-New 6000 (California Hardcoating). Company) can be used.

  In addition, examples of the curable resin used in the hard coat layer according to this embodiment include a thermosetting resin and an ultraviolet curable resin, but an ultraviolet curable resin is preferable because of easy molding, and among them, a pencil More preferred is a hardness of at least 2H. Such curable resins can be used singly or in combination of two or more.

Active energy ray curable resin hard coat material It is also preferable to use an active energy ray curable resin as the hard coat material. The active energy ray resin refers to a resin that is cured through a crosslinking reaction or the like by irradiation with active rays such as ultraviolet rays or electron beams. As the active energy ray curable resin, a component containing a monomer having an ethylenically unsaturated double bond is preferably used, and the active energy ray curable resin layer is cured by irradiation with an active ray such as an ultraviolet ray or an electron beam. It is formed. Typical examples of the active energy ray curable resin include an ultraviolet curable resin and an electron beam curable resin, and a resin curable by ultraviolet irradiation is preferable.

  As the ultraviolet curable resin, for example, an ultraviolet curable urethane acrylate resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, or an ultraviolet curable epoxy resin is preferable. Used. The UV curable acrylic urethane resin generally includes 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate (hereinafter referred to as acrylate) in addition to a product obtained by reacting a polyester polyol with an isocyanate monomer or a prepolymer. It can be easily obtained by reacting an acrylate monomer having a hydroxyl group such as 2-hydroxypropyl acrylate. For example, as described in JP-A-59-151110, 100 parts of Unidic (registered trademark) 17-806 (manufactured by DIC Corporation) and 1 part of Coronate (registered trademark) L (manufactured by Nippon Polyurethane Industry Co., Ltd.) A mixture or the like is preferably used. The UV curable polyester acrylate resin can be easily obtained by reacting a monomer such as 2-hydroxyethyl acrylate, glycidyl acrylate or acrylic acid with a hydroxyl group or carboxyl group at the end of the polyester (see, for example, JP-A No. 59-151112). The ultraviolet curable epoxy acrylate resin is obtained by reacting a terminal hydroxyl group of an epoxy resin with a monomer such as acrylic acid, acrylic acid chloride, or glycidyl acrylate. Examples of ultraviolet curable polyol acrylate resins include ethylene glycol (meth) acrylate, polyethylene glycol di (meth) acrylate, glycerin tri (meth) acrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, and dipenta. Examples include erythritol pentaacrylate, dipentaerythritol hexaacrylate, and alkyl-modified dipentaerythritol pentaacrylate.

  In this embodiment, it is preferable that the shrinkage stress of the hard coat layer is small. The shrinkage stress of the hard coat varies depending on the structure of the monomer, and particularly depends on the number of functional groups to be crosslinked, the number of functional groups not to be crosslinked, and the molecular weight.

  Moreover, it is preferable not to promote shrinkage even under sunlight exposure conditions. Therefore, it is preferable to contain a UV absorber or an antioxidant in the hard coat. As the ultraviolet absorber and the antioxidant, an ultraviolet absorber and an antioxidant used in an ultraviolet absorbing layer described later can be used. An antioxidant and a light stabilizer may be used in combination. Here, when the antioxidant and the light stabilizer are used in combination, the light stabilizer is not particularly limited. However, since the same light stabilizer as described in the section of the ultraviolet absorbing layer described later can be used, description thereof is omitted here. However, from the viewpoint of hard coat properties, it is preferable that the addition amount of the ultraviolet absorber is small. As a result, even if the hard coat layer contains an ultraviolet absorber, the ultraviolet absorbing layer is required separately.

  The hard coat layer is preferably a thin film in order to impart flexibility and flatness. Specifically, the thickness of the hard coat layer is preferably in the range of 0.1 to 50 μm, and more preferably in the range of 1 to 20 μm. If it is 0.1 μm or more, the hard coat property tends to be improved, and conversely, if it is 50 μm or less, the transparency of the light reflecting film tends to be improved.

  The hard coat layer preferably contains inorganic fine particles. Preferred inorganic fine particles include fine particles of an inorganic compound containing a metal such as titanium, silica, zirconium, aluminum, magnesium, antimony, zinc or tin. The average particle size of the inorganic fine particles is preferably 1000 nm or less, and more preferably in the range of 10 to 500 nm, in order to ensure visible light transmittance. In addition, the inorganic fine particles have higher photopolymerization reactivity such as monofunctional or polyfunctional acrylates because the higher the bond strength with the cured resin that forms the hard coat layer, the more the falling off from the hard coat layer can be suppressed. Those having a group introduced on the surface are preferred.

  Further, the hue can be adjusted by adding a dye or a pigment to the hard coat.

  When the hard coat layer is provided as the outermost layer of the light reflecting film, the center line average roughness (Ra) of the hard coat layer is 3 nm or more and 20 nm or less, so that scattering of reflected light can be prevented and light collection efficiency is improved. It is preferable from the viewpoint.

  A method for forming the hard coat is not particularly limited, but the hard coat can be formed by applying a hard coat layer coating solution containing a material constituting the hard coat layer. Moreover, as a formation method of a hard coat, it can also form by dry film forming methods, such as vapor deposition. As an example of the method by coating, a material constituting the hard coat layer is dissolved or suspended in an appropriate solvent to prepare a coating solution. Next, the coating solution is applied by a predetermined coating method to form a coating film. When coating a coating film, various conventionally used coating methods such as spray coating method, spin coating method, bar coating method, gravure coating method, reverse coating method, die coating method and the like are conventionally known coating methods. Can be used.

  As the solvent, water or a conventionally known organic solvent can be used, and is not particularly limited. For example, alcohol such as methanol, ethanol, 1-propanol and isopropyl alcohol; aroma such as benzene, toluene, xylene, cyclohexane and n-hexane Aliphatic or aliphatic hydrocarbons; ester compounds such as methyl acetate, ethyl acetate, methyl acetoacetate and ethyl acetoacetate; ketone compounds such as acetone, methyl ethyl ketone (MEK) and methyl isobutyl ketone; cyclic ether compounds such as tetrahydrofuran and dioxane, etc. It can be used as appropriate. In addition, the said solvent may be used individually by 1 type, and may be used together 2 or more types.

  The solid content concentration of the material constituting the hard coat layer is preferably 10 to 50% by mass, more preferably 15 to 45% by mass, and further preferably 20 to 40% by mass with respect to the total mass of the hard coat layer solution. is there.

  Although it does not restrict | limit especially as a drying temperature after application | coating, Preferably it is 70-140 degreeC, More preferably, it is 70-110 degreeC, More preferably, it is 80-100 degreeC. The drying time is preferably 0.5 to 3 minutes, more preferably 0.5 to 2.5 minutes, and further preferably 0.5 to 2.0 minutes.

  In the case of a polysiloxane hard coat material, after application, after drying the solvent, in order to promote curing and crosslinking of the hard coat, heat curing is carried out within a temperature range of 50 to 150 ° C. for 30 minutes to several days. It is preferable to do. The temperature for heat curing is preferably 70 to 140 ° C, more preferably 70 to 110 ° C, and further preferably 80 to 100 ° C. Moreover, the time of heat curing becomes like this. Preferably it is 90 to 180 minutes, More preferably, it is 100 to 150 minutes, More preferably, it is 100 to 140 minutes. However, in this case, the setting of the drying temperature and the curing temperature below the heat deformation temperature of the resin base material and other layers forming the light reflecting film is a prerequisite.

[UV absorbing layer]
The light reflecting film of this embodiment essentially includes an ultraviolet absorbing layer. The ultraviolet absorbing layer is preferably a layer containing a light-transmissive resin material and an ultraviolet absorber. The reason why a resin material having light transmittance is preferably used is that the reflection of sunlight is performed by the light reflection layer, and therefore the ultraviolet absorption layer positioned on the light reflection layer needs to be a component that transmits sunlight. It is.

  The content of the light-transmitting resin material in the ultraviolet absorbing layer is preferably more than 50 mass% and 99.9 mass% or less, and 80 mass% or more and 99.9 mass% or less with respect to the total mass of the layer. It is more preferable that it is 85 mass% or more and 99 mass% or less, and it is especially preferable that it is 90 mass% or more and 97 mass% or less. In addition, since other layers such as a hard coat layer may be provided on the ultraviolet absorbing layer, it is preferable that the resin material having optical transparency also has a role of improving adhesion at that time. .

  Although there is no restriction | limiting in particular in the resin material used for an ultraviolet absorption layer, Various conventionally well-known synthetic resins 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 Cycloolefin such as resin, nylon, acrylic resin such as polymethyl methacrylate (PMMA), polyarylate, Arton (registered trademark) (trade name, manufactured by JSR Corporation) or Apel (registered trademark) (trade name, manufactured by Mitsui Chemicals, Inc.) Based resins and the like.

  Among the resin materials exemplified above, an acrylic resin can be suitably used as the translucent resin. The acrylic resin preferably contains 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, for example, an alkyl ester of methacrylic acid can be used. A particularly preferred methacrylic resin is polymethyl methacrylate (PMMA).

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

  Examples of the alkyl methacrylate include methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate and the like, and the carbon number of the alkyl group is preferably 1-8, more preferably 1-4. Of these, methyl methacrylate is preferably used. EMB series such as EMB457 (Mitsubishi Rayon Co., Ltd. acrylic resin), SRB215 (Asahi Kasei Chemicals Co., Ltd. acrylic rubber), Delpet (registered trademark) (Asahi Kasei Chemicals Co., Ltd. acrylic resin) etc. are used as commercial products. Also good.

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

  Moreover, you may have monomers other than alkyl methacrylate and alkyl acrylate. 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, that is, an intramolecular molecule. A compound having at least two polymerizable functional groups may be used. 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. Among the above, diisocyanates are preferable, and 1,6-hexamethylene diisocyanate is more preferable.

  The methacrylic resin preferably has a glass transition temperature of 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 can be used for an ultraviolet absorption layer, For example, organic, such as a thiazolidone type, a benzotriazole type, an acrylonitrile type, a benzophenone type, an aminobutadiene type, a triazine type, a phenyl salicylate, a benzoate type And ultraviolet powders such as cerium oxide and magnesium oxide, titanium oxide, zinc oxide, iron oxide and the like.

  Among these, an organic ultraviolet absorber is particularly preferable from the viewpoint of the initial reflectivity and suppression of a decrease in reflectivity over time. It is assumed that a higher initial reflectance can be obtained because of the good transmittance of light other than ultraviolet rays. Further, it is presumed that a higher effect of suppressing the decrease in reflectance over time can be obtained because the ultraviolet absorption effect is higher and coloring due to deterioration of the ultraviolet absorption layer itself hardly occurs.

  As organic ultraviolet absorbers, for example, JP-A-46-3335, JP-A-55-152776, JP-A-5-197004, JP-A-5-232630, JP-A-5-307232, JP-A-6-218131, and JP-A-8- No. 53427, No. 8-234364, No. 8-239368, No. 9-31067, No. 10-115898, No. 10-147777, No. 10-182621, German Patent No. 19739797A, European Patent No. 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, the molecular weight is low from the viewpoint of being able to effectively improve the weather resistance with a relatively small amount of addition because it is difficult to volatilize at a high boiling point and hardly scatters during high temperature molding. More than 400 UV absorbers are preferred. In addition, an ultraviolet absorber having a molecular weight of 400 or more has a low transferability from a thin translucent resin layer to other constituent layers and is difficult to precipitate on the surface of the laminate, so that the amount of contained ultraviolet absorber is long. It is preferable from the standpoints that the time is maintained and the durability of the weather resistance improving effect is excellent.

  Examples of the ultraviolet absorber having a molecular weight of 400 or more include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2,2-methylenebis [4- ( 1,1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) ) -4- (1,1,3,3-tetramethylbutyl) phenol and other benzotriazoles, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2) , 6,6-pentamethyl-4-piperidyl) sebacate and the like, and further 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonic acid (1,2,2,6,6-pentamethyl-4-piperidyl), 1- [2- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4 -[3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine and the like have both hindered phenol and hindered amine structures in the molecule A hybrid type is mentioned.

  Among organic ultraviolet absorbers, benzotriazole-based and triazine-based ultraviolet absorbers are preferable.

  The benzotriazole-based ultraviolet absorber is not particularly limited, and examples thereof include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2,2-methylenebis. [4- (1,1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (2H-benzotriazol-2-yl) -6- (1-methyl- 1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol, 2- (2-hydroxy-5-tert-butylphenyl) -2H-benzotriazole, 2- (5-chloro- 2-benzotriazolyl) -6-tert-butyl-p-cresol 2- (2-hydroxy-5-tert-octylphenyl) benzotriazole, 2- (2H-ben Zotriazol-2-yl) -6-dodecyl-4-methylphenol and the like.

  Among these, from the viewpoints of the molecular weight and light resistance described above, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2,2-methylenebis [4- (1,1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (2H-benzotriazol-2-yl) -6- (1-methyl- 1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol is more preferred, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H -Benzotriazole is more preferable, and 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole is particularly preferable.

  As the benzotriazole-based UV absorber, Tinuvin (registered trademark) P, P FL, 234, 326, 326 FL, 329, 329FL, 213, 571, PS, 99-2, 384-2, manufactured by BASF Japan Ltd., Commercial products such as 900, 928, and 1130 can also be used as appropriate.

  Although it does not restrict | limit especially as a triazine type ultraviolet absorber, A hydroxyphenyl triazine (HPT) type ultraviolet absorber etc. can be used preferably. Moreover, as a triazine type ultraviolet absorber, commercially available products such as Tinuvin (registered trademark) 1577 ED, 400, 405, 460, 477, 479 manufactured by BASF Japan Ltd. may be used as appropriate.

  These ultraviolet absorbers can be used alone or in combination of two or more.

The content of the ultraviolet absorber in the ultraviolet absorbing layer is preferably 0.1 to 20% by mass, more preferably 1 to 15% by mass, with respect to the total mass of the ultraviolet absorbing layer. More preferably, it is mass%. Moreover, it is preferable that content per film unit area is 0.1-3.0 g / m < ² >, and, as for content to the ultraviolet absorption layer of a ultraviolet absorber, it is 0.4-2.5 g / m < ² >. More preferably. By setting the content to the above range, it is possible to further prevent the roll and the film from being soiled due to the bleeding out of the ultraviolet absorber while exhibiting more weather resistance.

(Antioxidant)
In order to prevent deterioration of the ultraviolet absorber layer, the ultraviolet absorber 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 embodiment, the above-described antioxidant and a known light stabilizer can be used in combination. Examples of the light stabilizer include hindered amine light stabilizers.

  The ultraviolet light absorbing layer preferably has a light transmittance at 380 nm of 0 to 10%, more preferably 0 to 5%, and still more preferably 0 to 1%. The transmittance at 380 nm can be determined using, for example, a spectrophotometer U-4100 manufactured by Hitachi High-Tech Science under the conditions of a measurement wavelength of 380 to 780 nm, a scan speed of 600 nm / min, a sampling interval of 1 nm, and a slit of 5 nm.

  The thickness of the ultraviolet absorbing layer is preferably 1 to 150 μm. A film thickness of 1 μm or more is preferable because a material to be added when providing functionality such as protection of the light reflection layer and UV protection can be sufficiently added. The thickness of 150 μm or less is preferable from the viewpoint of maintaining an appropriate thickness of the entire light reflecting film. More preferably, it is 1-100 micrometers, More preferably, it is 3-80 micrometers.

  Furthermore, the thickness of the ultraviolet absorbing layer is preferably 5 to 30 μm from the viewpoint of achieving both the performance of the ultraviolet absorbing layer and the performance and weather resistance of the light reflecting film. By setting the film thickness to 5 μm or more, an even higher ultraviolet absorption effect can be obtained. By setting the film thickness to 30 μm or less, a higher image clarity (DOI) value can be obtained. In addition, the initial light collection efficiency, as well as a decrease in light collection efficiency over time in the outdoor environment, the occurrence of cracks, and adhesion It is possible to further enhance the effect of improving the decrease in sex. The reason why such an effect can be obtained is to reduce the influence of the pressure on the film surface due to the tension applied to the film in the manufacturing process including the winding process by reducing the film thickness. I guess this is because I can do it. That is, it is presumed that the film thickness can be obtained by reducing the deformation of the layer due to the pressure on the film surface and reducing the unevenness of the film surface and the unevenness of the residual stress. From the same viewpoint, the thickness of the ultraviolet absorbing layer is more preferably 10 to 25 μm, further preferably 15 to 25 μm, and particularly preferably 15 to 20 μm.

  From the above, a preferred embodiment of the present invention includes a light reflecting film in which the thickness of the ultraviolet absorbing layer is 10 to 25 μm.

  The method for forming the ultraviolet absorbing layer is not particularly limited, and examples thereof include a coating method. As an example of the method by coating, the material constituting the ultraviolet absorbing 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 coating a coating film, various conventionally used coating methods such as spray coating method, spin coating method, bar coating method, gravure coating method, reverse coating method, die coating method and the like are conventionally known coating methods. Can be used.

  As the organic solvent, conventionally known organic solvents can be used, and are not particularly limited. For example, alcohols such as methanol, ethanol, 1-propanol and isopropyl alcohol; aromatics such as benzene, toluene, xylene, cyclohexane and n-hexane; Aliphatic hydrocarbons; ester compounds such as methyl acetate, ethyl acetate, methyl acetoacetate, and ethyl acetoacetate; ketone compounds such as acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone; cyclic ether compounds such as tetrahydrofuran and dioxane are used as appropriate. be able to. In addition, the said solvent may be used individually by 1 type, and may be used together 2 or more types.

  The solid content concentration of the material constituting the ultraviolet absorbing layer is preferably 10 to 40% by mass, more preferably 15 to 35% by mass, and further preferably 20 to 30% by mass with respect to the total mass of the solution for the ultraviolet absorbing layer. It is.

  Although it does not restrict | limit especially as drying temperature after application | coating, Preferably it is 65-100 degreeC, More preferably, it is 70-90 degreeC, More preferably, it is 75-85 degreeC, As drying time, Preferably it is 0.5-5 Minutes, more preferably 1 to 3 minutes, still more preferably 1.5 to 2.5 minutes.

[Resin substrate]
The light reflecting film of this embodiment essentially has at least one resin substrate. The resin substrate has a role of supporting the light reflecting layer and maintaining the mechanical strength of the entire light reflecting film. Moreover, when manufacturing a light reflection film, a resin base material is good also as a board | substrate for forming another layer.

  In addition, the light reflection film may have a plurality of resin base materials, and in this case, the plurality of resin base materials may be the same or different.

  Examples of the resin constituting the resin substrate include polycarbonate, polyarylate, polysulfone, polyethersulfone, polyethylene terephthalate, polyethylene naphthalate, modified polyester, and the like, polyethylene, polypropylene, cellulose, diacetylcellulose, triacetylcellulose, and cellulose. Cellulose esters such as acetate propionate and cellulose acetate butyrate, polyvinyl chloride (soft polyvinyl chloride, hard polyvinyl chloride), polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polystyrene, syndiotactic polystyrene , Styrene / acrylonitrile copolymer, polyacetal, epoxy resin, phenol resin, cycloolefin polymer And acrylic resins such as mer, polynorbornene, polymethylpentene, polyetherketone, polyetheretherketone, polyetherketoneimide, polyamide, polyimide, polysulfone, polyethersulfone, fluororesin, polymethyl (meth) acrylate, etc. it can. Among these, from the viewpoint of heat resistance and dimensional stability, polycarbonate, polyester, polynorbornene, cellulose ester, and acrylic resin are preferable, polyester and acrylic resin are more preferable, polyester is more preferable, and polyethylene terephthalate is particularly preferable. These resins may be used alone or in combination of two or more.

  Further, the resin base material may contain an ultraviolet absorber or an antioxidant. As the ultraviolet absorber or antioxidant, the ultraviolet absorber or antioxidant used in the aforementioned ultraviolet absorbing layer can be used. An antioxidant and a light stabilizer may be used in combination. Here, when the antioxidant and the light stabilizer are used in combination, the light stabilizer is not particularly limited, but the same light stabilizer as that described in the item of the ultraviolet absorbing layer described above can be used, and thus the description thereof is omitted here. However, from the viewpoint of reducing the possibility of occurrence of bleeding out, it is preferable that the addition amount of the ultraviolet absorber is small. Thus, even when the resin base material containing the ultraviolet absorber is present between the hard coat layer and the ultraviolet absorbing layer, the ultraviolet absorbing layer is separately required.

  The thickness of the resin substrate is not particularly limited and can be appropriately set according to the type and purpose of the resin, but is preferably 10 to 250 μm from the viewpoint of achieving both the mechanical strength and flexibility of the light reflecting film. More preferably, it is 20-200 micrometers.

  The manufacturing method of the resin base material of this embodiment is not particularly limited, and for example, a film manufactured by a method such as a melt casting film forming method or a solution casting film forming method can be appropriately used. The resin substrate may be an unstretched film or a stretched film (for example, a uniaxially stretched film, a biaxially stretched film, etc.).

  Commercially available products such as Tetoron (registered trademark) film HB manufactured by Teijin DuPont Films Ltd., A4300 manufactured by Toyobo Co., Ltd. may be used as the resin base material.

[Light reflection layer]
The light reflecting film of this embodiment essentially includes a light reflecting layer.

  A light reflection layer is comprised from the metal etc. which have the function to reflect sunlight. The surface reflectance of the light reflection layer is preferably 90% or more, more preferably 93% or more.

  As a material constituting the light reflection layer, aluminum (Al), silver (Ag), chromium (Cr), copper (Cu), nickel (Ni), titanium (Ti), magnesium (Mg), rhodium (Rh), Examples thereof include metals containing at least one element selected from the group consisting of platinum (Pt) and gold (Au). Especially, it is preferable that aluminum (Al) or silver (Ag) is the main component from viewpoints of a reflectance, corrosion resistance, etc., it is more preferable that silver (Ag) is the main component, and it consists of silver (Ag). Is more preferable. The “main component” means that the component of the light reflecting layer is more than 50% by mass, preferably 80% by mass or more, more preferably 90% or more, and further preferably 95% or more. Especially preferably, it is 98 mass% or more, Most preferably, it is 100 mass%.

The light reflection layer may have a configuration in which one or more layers made of the above metals (metal reflection layer) are laminated. Moreover, a layer made of a metal oxide such as SiO ₂ or TiO ₂ may be provided on the metal reflective layer to further improve the reflectance.

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

  The method for forming the light reflecting layer is not particularly limited, and 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. Specifically, a vacuum such as a resistance heating vacuum deposition method, an electron beam heating vacuum deposition method, an ion plating method, or an ion beam assisted vacuum deposition method is used. There are vapor deposition and sputtering. Especially, it is preferable to use the dry method (especially vacuum evaporation method) in which the film formation by a roll-to-roll system is possible.

[Adhesive layer]
The light reflecting film of this embodiment may have an adhesive layer. An adhesive layer is a layer provided in order to adhere | attach an interlayer and between a layer and a base material. Therefore, it is preferable that the adhesive layer has adhesiveness for adhering various layers, heat resistance that can withstand heat when other layers are formed, and smoothness for drawing out high reflection performance of the light reflecting film.

  One preferable form of the light reflecting film of this embodiment is a light reflecting film further having an adhesive layer on the side opposite to the ultraviolet absorbing layer side of the light reflecting layer.

  The adhesive layer is not particularly limited as long as it has a function of improving the adhesion between the layers and between the layer and the substrate, but is preferably made of a resin. The resin used as the binder for the adhesive layer is not particularly limited as long as it satisfies the conditions of adhesion, heat resistance, and smoothness, such as polyester resin, acrylic resin, melamine resin, epoxy resin, Polyamide resins, vinyl chloride resins, vinyl chloride vinyl acetate copolymer resins, etc. can be used alone or mixed resins thereof. From the viewpoint of weather resistance, mixed resins of polyester resins and melamine resins are preferred, and isocyanates etc. It is more preferable to use a thermosetting resin mixed with a curing agent.

  As the resin used for the adhesive layer, Polyester (registered trademark) SP181 manufactured by Nippon Synthetic Chemical Industry Co., Ltd., which is a polyester resin, and Superbecamine (registered trademark) J-820 manufactured by DIC, which is a melamine resin, are commercially available You may use goods.

  The curing agent such as isocyanate used for the adhesive layer is not particularly limited, but for example, 2,4-tolylene diisocyanate which is TDI (toluene diisocyanate) isocyanate, 1,6-hexamethylene diisocyanate which is HMDI isocyanate, and the like. Can be mentioned.

  The thickness of the adhesive layer is preferably 0.01 to 150 μm. A film thickness of 0.01 μm or more is preferable from the viewpoint of sufficiently providing adhesion between the layers and between the layer and the substrate. Moreover, it is preferable to set it as 150 micrometers or less from a viewpoint which can maintain the thickness of the whole light reflection film moderately. More preferably, it is 0.1-100 micrometers, More preferably, it is 1-80 micrometers.

  Furthermore, from the viewpoint of compatibility between the performance of the adhesive layer and the performance and weather resistance of the light reflecting film, in a preferred embodiment of the present invention, the thickness of the adhesive layer is preferably 3 to 30 μm. By setting the film thickness to 3 μm or more, higher adhesion can be obtained. By setting the film thickness to 30 μm or less, a higher image clarity (DOI) value can be obtained. In addition, the initial light collection efficiency, as well as a decrease in light collection efficiency over time in the outdoor environment, the occurrence of cracks, and adhesion It is possible to further enhance the effect of improving the decrease in sex. The reason why such an effect can be obtained is to reduce the influence of the pressure on the film surface due to the tension applied to the film in the manufacturing process including the winding process by reducing the film thickness. I guess it is because you can. That is, it is presumed that the film thickness can be obtained by reducing the deformation of the layer due to the pressure on the film surface and reducing the unevenness of the film surface and the unevenness of the residual stress. From the same viewpoint, the thickness of the adhesive layer is more preferably 5 to 25 μm, further preferably 10 to 25 μm, and particularly preferably 15 to 20 μm.

  From the above, as a preferred embodiment of the present invention, there is a light reflecting film in which the thickness of the adhesive layer is 5 to 25 μm.

  The method for forming the adhesive layer is not particularly limited, and examples thereof include a coating method. As an example of the method by coating, a material constituting the adhesive 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 coating a coating film, various conventionally used coating methods such as spray coating method, spin coating method, bar coating method, gravure coating method, reverse coating method, die coating method and the like are conventionally known coating methods. Can be used.

  As the organic solvent, conventionally known organic solvents can be used, and are not particularly limited. For example, alcohols such as methanol, ethanol, 1-propanol and isopropyl alcohol; aromatics such as benzene, toluene, xylene, cyclohexane and n-hexane; Aliphatic hydrocarbons; ester compounds such as methyl acetate, ethyl acetate, methyl acetoacetate, and ethyl acetoacetate; ketone compounds such as acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone; cyclic ether compounds such as tetrahydrofuran and dioxane are used as appropriate. be able to. In addition, the said solvent may be used individually by 1 type, and may be used together 2 or more types.

  The solid content concentration of the material constituting the adhesive layer is preferably 1 to 40% by mass, more preferably 3 to 30% by mass, and further preferably 5 to 20% by mass with respect to the total mass of the solution for the ultraviolet absorbing layer. is there.

  Although it does not restrict | limit especially as drying temperature after application | coating, Preferably it is 65-100 degreeC, More preferably, it is 70-90 degreeC, More preferably, it is 75-85 degreeC, As drying time, Preferably it is 0.5-5 Minutes, more preferably 1 to 3 minutes, still more preferably 1.5 to 2.5 minutes.

[Corrosion prevention layer]
The light reflecting film of this embodiment preferably has a corrosion prevention layer. A corrosion prevention layer is a layer provided in order to prevent corrosion of a light reflection layer. Moreover, it is preferable to arrange | position a corrosion prevention layer so that it may adjoin directly to a light reflection layer.

  The corrosion prevention layer may contain a corrosion inhibitor and a binder.

  Examples of the binder for the corrosion prevention layer include cellulose ester, polycarbonate, polyarylate, polysulfone (including polyethersulfone), polyethylene terephthalate, polyethylene naphthalate and other polyesters, polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, Cellulose acetate propionate, cellulose acetate butyrate, polyvinylidene chloride, polyvinyl alcohol, ethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, polynorbornene, polymethylpentene, polyether ketone, polyether ketone imide, polyamide, fluororesin, Nylon, melamine resin or acrylic resin (polymethyl methacrylate Etc.), and the like. Of these, melamine resin and acrylic resin are preferable. Further, the corrosion prevention layer may include a curing agent such as 2.4-tolylene diisocyanate.

  As the binder, a commercial product such as Super Becamine (registered trademark) J-820 manufactured by DIC Corporation, which is a melamine resin, may be used.

  As a corrosion inhibitor, it is preferable to have an adsorptive group with respect to the metal which comprises a light reflection layer. Here, “corrosion” refers to a phenomenon in which a metal is chemically or electrochemically eroded or deteriorated in material by an environmental substance surrounding it (see JIS Z0103: 2004).

  Examples of the corrosion inhibitor having an adsorptive group for metals 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 imidazole rings. It is preferable to be selected from at least one of a compound having an indazole ring, a compound having an indazole ring, a copper chelate compound, a thiourea, a compound having a mercapto group, a naphthalene compound, or a mixture of two or more 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. More specifically, corrosion inhibitors described in paragraphs “0063” to “0072” of JP2012-232538A can be used.

  The corrosion inhibitor is not particularly limited, and examples thereof include glycol dimercaptoacetate.

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

  The corrosion prevention layer may consist of only one layer or may consist of a plurality of layers. The thickness of the corrosion prevention layer is preferably 30 to 200 nm, more preferably 20 to 100 nm.

  The method for forming the corrosion prevention layer is not particularly limited, and examples thereof include a coating method. As an example of the method by coating, the material constituting the corrosion prevention 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 coating a coating film, various conventionally used coating methods such as spray coating method, spin coating method, bar coating method, gravure coating method, reverse coating method, die coating method and the like are conventionally known coating methods. Can be used.

  As the organic solvent, conventionally known organic solvents can be used, and are not particularly limited. For example, alcohols such as methanol, ethanol, 1-propanol and isopropyl alcohol; aromatics such as benzene, toluene, xylene, cyclohexane and n-hexane; Aliphatic hydrocarbons; ester compounds such as methyl acetate, ethyl acetate, methyl acetoacetate, and ethyl acetoacetate; ketone compounds such as acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone; cyclic ether compounds such as tetrahydrofuran and dioxane are used as appropriate. be able to. In addition, the said solvent may be used individually by 1 type, and may be used together 2 or more types.

  The solid content concentration of the material constituting the corrosion prevention layer is preferably 1 to 40% by mass, more preferably 1 to 30% by mass, and further preferably 1 to 20% by mass with respect to the total mass of the solution for the corrosion prevention layer. It is.

  Although it does not restrict | limit especially as drying temperature after application | coating, Preferably it is 65-150 degreeC, More preferably, it is 80-140 degreeC, More preferably, it is 90-120 degreeC, As drying time, Preferably it is 0.5-5 Minutes, more preferably 1 to 3 minutes, still more preferably 1.5 to 2.5 minutes.

[Anchor layer]
The light reflecting film of this embodiment preferably has an anchor layer. The anchor layer is made of a resin, and is a layer provided to bring a resin-containing layer or a resin base material and the light reflection layer into close contact (for example, between the resin base material and the light reflection 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. It is preferable to have smoothness for drawing out the performance.

  The resin used for the anchor layer is not particularly limited as long as it satisfies the above conditions of adhesion, heat resistance, and smoothness. For example, polyester resin, polyurethane resin, acrylic resin, melamine resin, epoxy resin, Polyamide resin, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer resin or the like alone or a mixed resin thereof can be used. From the viewpoint of weather resistance, a mixed resin of a polyester resin and a melamine resin or a mixed resin of a polyester resin and a urethane resin is preferable, and a thermosetting resin in which a curing agent such as isocyanate or epoxy is further mixed is more preferable.

  As the resin used for the anchor layer, a commercially available product such as Super Becamine (registered trademark) J-820 manufactured by DIC Corporation, which is a melamine resin, may be used.

  Further, the anchor layer can be made to contain the corrosion inhibitor described in the above-mentioned section “Corrosion prevention layer” and also have a function as a corrosion prevention layer.

  The thickness of the anchor layer is preferably 0.01 to 3 μm, more preferably 0.05 to 2 μm. By satisfying this range, the unevenness on the surface of the resin substrate can be covered while maintaining the adhesion, the smoothness can be improved, and the anchor layer can be sufficiently cured, resulting in the reflection of the light reflecting film. The rate can be increased.

  The method for forming the anchor layer is not particularly limited, and examples thereof include a coating method. As an example of the method by coating, the material constituting the anchor 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 coating a coating film, various conventionally used coating methods such as spray coating method, spin coating method, bar coating method, gravure coating method, reverse coating method, die coating method and the like are conventionally known coating methods. Can be used.

  As the organic solvent, conventionally known organic solvents can be used, and are not particularly limited. For example, alcohols such as methanol, ethanol, 1-propanol and isopropyl alcohol; aromatics such as benzene, toluene, xylene, cyclohexane and n-hexane; Aliphatic hydrocarbons; ester compounds such as methyl acetate, ethyl acetate, methyl acetoacetate, and ethyl acetoacetate; ketone compounds such as acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone; cyclic ether compounds such as tetrahydrofuran and dioxane are used as appropriate. be able to. In addition, the said solvent may be used individually by 1 type, and may be used together 2 or more types.

  The solid content concentration of the material constituting the anchor layer is preferably 1 to 40% by mass, more preferably 1 to 30% by mass, and further preferably 1 to 20% by mass with respect to the total mass of the anchor layer solution. .

  Although it does not restrict | limit especially as drying temperature after application | coating, Preferably it is 65-150 degreeC, More preferably, it is 80-140 degreeC, More preferably, it is 90-120 degreeC, As drying time, Preferably it is 0.5-5 Minutes, more preferably 1 to 3 minutes, still more preferably 1.5 to 2.5 minutes.

[Gas barrier layer]
The light reflecting film of this embodiment may have a gas barrier layer on the hard coat layer side with respect to the light reflecting layer. The gas barrier layer is intended to prevent deterioration of the humidity, especially 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 uses. As long as it has the function of preventing deterioration, a gas barrier layer of various modes can be provided. In one preferred embodiment, the hard coat layer described above may function as a gas barrier layer.

The moisture-proof barrier layer, 40 ° C., the water vapor permeability at 90% RH, is preferably not more than 1g ^/ m 2 · day, more preferably at most 0.5g ^/ m 2 · day, 0 More preferably, it is 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 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. A precursor of an inorganic oxide 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.

  The inorganic oxide is formed by local heating from a sol using an organometallic compound as a raw material. For example, silicon (Si), aluminum (Al), zirconium (Zr), titanium (Ti), tantalum (Ta), zinc (Zn), barium (Ba), indium (In) contained in the organometallic compound, An oxide of an element such as tin (Sn) or niobium (Nb), such as silicon oxide, aluminum oxide, or zirconium oxide. Of these, silicon oxide is preferred.

  As a method for forming the inorganic oxide, it is preferable to use a so-called sol-gel method or a polysilazane method. The sol-gel method is a method of forming an inorganic oxide from an organometallic compound that is a precursor of an inorganic oxide, and the polysilazane method is a method of forming an inorganic oxide from a polysilazane that is a precursor of an inorganic oxide. For the compounds and details used in the sol-gel method, the compounds and methods described in paragraphs “0174” to “0191” of JP2012-232538A can be appropriately employed.

[Adhesive layer]
The light reflecting film of this embodiment may have an adhesive layer for bonding to a support substrate described later. The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited, and examples thereof include acrylic pressure-sensitive adhesives, silicone pressure-sensitive adhesives, urethane pressure-sensitive adhesives, polyvinyl butyral pressure-sensitive adhesives, and ethylene-vinyl acetate pressure-sensitive adhesives. Can do.

  The acrylic pressure-sensitive adhesive may be either solvent-based or emulsion-based, but is preferably a solvent-based pressure-sensitive adhesive because it is easy to increase the adhesive strength and the like, and among them, those obtained by solution polymerization are preferable. As a raw material in the case of producing such a solvent-based acrylic pressure-sensitive adhesive by solution polymerization, for example, an acrylic ester such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, acryl acrylate, As a comonomer for improving the cohesive force, vinyl acetate, acrylonitrile, styrene, methyl methacrylate, etc., to further promote crosslinking, to give a stable adhesive force, and to maintain a certain adhesive force even in the presence of water Examples of the functional group-containing monomer include methacrylic acid, acrylic acid, itaconic acid, hydroxyethyl methacrylate, and glycidyl methacrylate. Since the adhesive layer of the laminated film requires a particularly high tack as the main polymer, those having a low glass transition temperature (Tg) such as butyl acrylate are particularly useful.

  This adhesive layer contains additives such as stabilizers, surfactants, UV absorbers, flame retardants, antistatic agents, antioxidants, thermal stabilizers, lubricants, fillers, coloring, adhesion modifiers, etc. It can also be made.

  The thickness of the adhesive layer is preferably 1 μm to 100 μm, more preferably 3 to 50 μm. If it is 1 micrometer or more, there exists a tendency for adhesiveness to improve and sufficient adhesive force is acquired. Conversely, if it is 100 μm or less, the transparency of the optical film can be improved.

[Peeling layer]
The light reflecting film of this embodiment may have a release layer on the outermost layer on the ultraviolet absorbing layer side with respect to the hard coat layer. For example, when a light reflecting film is shipped, it is shipped with the release layer attached to the adhesive layer, the light reflecting film having the adhesive layer is peeled off from the release layer, and the light reflecting film is attached to a support substrate and light from a solar reflective device or the like. Used as a reflector.

  The release layer is not particularly limited as long as it can provide protection of the light reflecting 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 sheet , Plastic film or sheet such as fluororesin film, resin film or sheet kneaded with titanium oxide, silica, aluminum powder, copper powder, etc., coating the resin kneaded with these, or metal deposition such as aluminum by metal vapor deposition, etc. It is possible to use a resin film or sheet that has been surface-treated.

  Although there is no restriction | limiting in particular in the thickness of a peeling layer, Usually, it is preferable that it is the range of 12-250 micrometers.

  Furthermore, the light reflecting film of the present embodiment has a conductive layer, an antistatic layer, an easy adhesion layer, an antifouling layer, a deodorizing layer, a droplet layer, an easy slip layer, and an abrasion resistance depending on the environment and application used. Layer, antireflection layer, electromagnetic wave shielding layer, infrared absorption layer, printing layer, fluorescent light emitting layer, hologram layer, specific wavelength light cut layer (metal layer, liquid crystal layer, etc.), colored layer (visible light absorption layer), laminated glass It may have one or more functional layers such as an intermediate film layer used in the above.

<Method for producing light reflecting film>
A light reflecting film can be produced by appropriately laminating the above-described constituent layers. Hereinafter, although the embodiment of a manufacturing method is described about the light reflection film which is a desirable form of the present invention as an example, the present invention is not limited to the following form.

  Here, the manufacturing method of the light reflection film shown in FIG. 1, which is a preferable embodiment of the present invention, will be described as an example.

First, a resin base material 14 is prepared;
Next, an anchor layer forming step of forming the anchor layer 16 on one surface of the resin base material 14 is performed;
Next, a light reflection layer forming step of forming the light reflection layer 13 on the formed anchor layer 16 is performed;
Next, a corrosion prevention layer forming step of forming the corrosion prevention layer 17 on the formed light reflection layer 13 is performed;
Next, an ultraviolet absorption layer forming step for forming the ultraviolet absorption layer 12 is performed on the surface opposite to the surface on which the anchor layer 16 of the resin base material 14 is formed;
Next, a hard coat layer forming step for forming the hard coat layer 11 is performed on the formed ultraviolet absorbing layer 12;
Next, an adhesive layer forming step for forming the adhesive layer 15 on the corrosion prevention layer 17 is performed;
And the resin base material 18 is arrange | positioned on the formed contact bonding layer 15, and the resin base material bonding process of bonding is implemented and the light reflection film 10 is formed by forming a laminated body;
And the light reflection film 10 can be manufactured by implementing the winding-up process which winds up the laminated body formed through said each process in roll shape as needed.

  Moreover, the manufacturing method of the light reflection film of FIG. 2 which is another preferable form of this invention is demonstrated to an example.

First, a resin base material 14 is prepared;
Next, an anchor layer forming step of forming the anchor layer 16 on one surface of the resin base material 14 is performed;
Next, a light reflection layer forming step of forming the light reflection layer 13 on the formed anchor layer 16 is performed;
Next, a corrosion prevention layer forming step of forming the corrosion prevention layer 17 on the formed light reflection layer 13 is performed;
Next, an ultraviolet absorption layer forming step of forming the ultraviolet absorption layer 12 on the formed corrosion prevention layer 17 is performed;
Next, the light reflecting film 10 is formed by performing a hard coat layer forming step of forming the hard coat layer 11 on the formed ultraviolet absorbing layer 12 to form a laminate.
And the light reflection film 10 can be manufactured by implementing the winding-up process which winds up the laminated body formed through said each process in roll shape as needed.

  In addition, since any one of the hard-coat layer 11, the ultraviolet absorption layer 12, the light reflection layer 13, and the resin base material 14 or 18 in FIG. 1 and FIG. 2 is an essential structural member in this invention, manufacture of an optical reflection film In the method, the preparation of the resin substrate, the light reflecting layer forming step, the ultraviolet absorbing layer forming step, and the hard coat layer forming step are essential. And other processes, such as the formation process of another structural member, the bonding process of the further resin base material, can be provided as needed.

  Here, when the layer directly formed on the surface of the light reflection layer is produced by a method by coating, the drying temperature after coating is preferably 65 to 150 ° C. By setting the drying temperature to 65 ° C. or higher, a higher image clarity (DOI) value can be obtained, and the initial light collection efficiency, as well as the deterioration of light collection efficiency over time in the outdoor environment, the occurrence of cracks, and The effect of improving the decrease in adhesion can be further enhanced. The reason why such an effect can be obtained is presumed to be that it is possible to further suppress non-uniform structures such as sea-island structures in the coating layer, which are formed when drying is slow, by speeding up drying. Yes. Moreover, a deformation | transformation of a resin base material can be reduced more by making drying temperature into 150 degrees C or less. From the same viewpoint, the drying temperature is preferably 80 to 140 ° C, more preferably 90 to 120 ° C. The drying time is preferably 0.5 to 5 minutes, more preferably 1 to 3 minutes, and further preferably 1.5 to 2.5 minutes.

  The layer directly formed on the surface of the light reflecting layer is not particularly limited, but is preferably a corrosion prevention layer and an anchor layer, and more preferably a corrosion prevention layer.

[Winding process]
Although the winding process is not particularly limited, for example, the film is wound around the winding roll while keeping the shortest distance between the outer peripheral surface of the cylindrical winding film and the outer peripheral surface of the mobile transport roll immediately before this constant. Methods and the like. Means such as a static elimination blower for removing or reducing the surface potential of the film may be provided in front of the take-up roll.

  The winding machine can be a commonly used one, and is not particularly limited. For example, a winding method such as a constant tension method, a constant torque method, a taper tension method, a program tension control method with a constant internal stress, etc. Can be rolled up.

  In addition, it is preferable that the winding tension | tensile_strength at the time of winding of a light reflection film is 50-230 N / m. When the winding tension is 50 N / m or more, the winding property becomes better. By setting the take-up tension to 230 N / m or less, a higher image clarity (DOI) value can be obtained. In addition, the initial light collection efficiency, as well as the degradation of light collection efficiency over time in the outdoor environment, the occurrence of cracks And the improvement effect of the adhesive fall can be further enhanced. The reason why such an effect can be obtained is to reduce the influence of the pressure on the film surface due to the tension applied to the film in the manufacturing process including the winding process by reducing the winding tension. I guess it can be because. That is, it is presumed that this is because the deformation of the layer due to the pressure on the film surface is reduced and the unevenness of the film surface and the unevenness of the residual stress are reduced. From the same viewpoint, the winding tension is more preferably 100 to 200 N / m, and further preferably 130 to 170 N / m.

  The temperature and humidity conditions in the winding process are not particularly limited, but the film is preferably wound under environmental conditions of a temperature of 20 to 30 ° C. and a humidity of 20 to 60% RH.

  The winding core for winding the film into a roll may be any material as long as it is a cylindrical core, but is preferably a hollow plastic core, and the plastic material is a heat treatment temperature. As long as it is a heat resistant plastic that can withstand the above, any resin such as phenol resin, xylene resin, melamine resin, polyester resin, and epoxy resin can be used. A thermosetting resin reinforced with a filler such as glass fiber is preferred.

  The diameter of the wound core is not particularly limited, and for example, a wound core having a diameter of 6 inches (1 inch = 2.54 cm) can be used. Specifically, for example, a hollow plastic core: a wound core made of FRP having an outer diameter of 6 inches and an inner diameter of 5 inches can be used.

  The number of windings to the winding core, the winding thickness, and the width of the light reflecting film are not particularly limited, but the number of windings to the winding core is preferably 100 windings or more, more preferably 500 windings or more, The winding thickness is preferably 5 cm or more, and the width of the light reflecting film is preferably 80 cm or more, and particularly preferably 1 m or more.

  In addition, in the manufacturing method of a light reflection film, as a combination of each process and its order, it is not limited above, The optimal method can be suitably used according to the structure to employ | adopt. Moreover, it can use suitably also about processes other than having described above.

<Light reflector>
Another preferable embodiment of the present invention is a light reflector in which a light reflecting film is bonded to a support substrate.

  The light reflector has a structure in which a light reflecting film is bonded to a self-supporting base material (support base material) via an adhesive layer. Here, the term “self-supporting” in the case of “self-supporting base material” means that, when cut to a size used as a base material for a light reflector, the opposite edge portions are supported. This means that the substrate has rigidity enough to carry the substrate. When the base material of the light reflector has self-supporting properties, it can be easily handled when installed in the solar light reflection device described later, and the holding member for holding the light reflector can have a simple configuration. Therefore, it is possible to reduce the weight of the solar reflective device. For example, when the solar reflective device is used as a solar reflective device for solar thermal power generation, power consumption during solar tracking can be suppressed.

  The support substrate may be a single layer or a shape in which a plurality of layers are laminated. Moreover, a single structure may be sufficient and it may be divided | segmented into plurality. The shape of the substrate is preferably a concave shape or can be a concave shape. Therefore, a base material that is variable from a flat shape to a concave shape may be used, or a base material that is fixed to a concave shape may be used. A base material that can be changed into a concave shape can be adjusted arbitrarily by adjusting the curvature of the base material. It is preferable because reflectance can be obtained. The base material having the concave shape fixed is preferable from the viewpoint of adjustment cost because it is not necessary to adjust the curvature.

  Materials for the supporting substrate include steel plates, copper plates, aluminum plates, aluminum-plated steel plates, aluminum-based alloy-plated steel plates, copper-plated steel plates, tin-plated steel plates, chrome-plated steel plates, stainless steel plates, and veneer plates (preferably waterproofed) Wood board, fiber reinforced plastic (FRP) board, resin board (resin film) and the like. Moreover, it is also possible to use the steel plate which combined resin and a metal plate.

  As a material of the resin film as the surface layer, various conventionally known resin films can be used. For example, a polycarbonate film, a polyester film such as polyethylene terephthalate, a norbornene resin film, a cellulose ester film, and an acrylic film are preferable, and a polyester film such as polyethylene terephthalate or an acrylic film is particularly preferable. The thickness of the resin film is preferably an appropriate thickness depending on the type and purpose of the resin. For example, generally, it is 10-250 micrometers, Preferably it is 20-200 micrometers.

<Sunlight reflector>
Another preferable embodiment of the present invention is a sunlight reflecting device having a light reflector.

  The solar light reflection device of this embodiment is suitably used for condensing sunlight in solar thermal power generation. The solar light reflection device of this embodiment includes a light reflector and a holding member that holds the light reflector.

  As a preferable form, when the solar light reflection device is used for solar power generation, a cylindrical member having a fluid inside is provided as a heat collecting part in the vicinity of the light reflecting film, and the solar light is reflected on the cylindrical member so as to reflect the sunlight. A form generally called a trough type is mentioned in which the fluid is heated and the heat energy is converted to generate electricity. Moreover, the form called a tower type | mold is also mentioned as another form. The tower-type configuration has at least one heat collecting part and at least one solar power solar reflection device for reflecting sunlight and irradiating the heat collecting part, and is collected in the heat collecting part. There is one that uses liquid heat to heat a liquid and turn a turbine to generate electricity. In addition, it is preferable that a plurality of solar power generation solar reflective devices are arranged around the heat collection unit. Moreover, it is preferable that a plurality of solar reflective devices for solar thermal power generation are arranged concentrically or in a concentric fan shape. In addition, sunlight is reflected to the collector mirror by the sunlight reflecting mirrors installed around the support tower, and then reflected further by the collector mirror and sent to the heat collector and sent to the heat exchange facility. It is done. The solar light reflection device of this embodiment can be used for both trough type and tower type. Of course, it can be used for various other types of solar thermal power generation.

  The sunlight reflecting device has a holding member that holds the light reflector. The holding member is preferably held in a state in which the light reflector can track the sun. Although there is no restriction | limiting in particular as a form of a holding member, For example, the form which hold | maintains several places with a rod-shaped holding member is preferable so that a light reflector can hold | maintain a desired shape. The holding member preferably has a configuration for holding the light reflector in a state where the sun can be tracked. However, when the sun is tracked, it 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.

  The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples. In addition, in the following Examples, unless otherwise specified, measurements of operation and physical properties were performed under conditions of room temperature (20 to 25 ° C.) / Relative humidity 40 to 50%. Further, unless otherwise specified, “%” and “part” mean “% by mass” and “part by mass”, respectively.

<Production of light reflecting film>
Example 1
(Resin substrate 1)
A biaxially stretched polyester film (manufactured by Toyobo Co., Ltd., polyethylene terephthalate A4300 with an easy-adhesion layer, thickness 50 μm) was prepared as a resin substrate.

(Resin substrate 2)
A polyester film (manufactured by Teijin DuPont Films, Tetron (registered trademark) film HB, thickness 25 μm) was prepared as a resin substrate.

(Preparation of anchor layer solution)
Super Becamine (registered trademark) J-820 (melamine resin, manufactured by DIC Corporation) was mixed in methyl ethyl ketone (MEK) so that the solid content concentration was 5% by mass to prepare an anchor layer solution.

(Preparation of UV absorbing layer solution)
Polymethyl methacrylate (PMMA) resin (Mitsubishi Rayon Co., Ltd., EMB457), acrylic rubber (Asahi Kasei Chemicals Co., Ltd., SRB215), zinc oxide UV absorber (Sumitomo Osaka Cement Co., Ltd., ZnO-350) Was mixed in methyl ethyl ketone (MEK) so that the solid concentration was 25: 3% by mass at 17: 3: 1.5 (solid content mass ratio) to prepare an ultraviolet absorbing layer solution.

(Preparation of hard coat layer solution)
A solution for a hard coat layer was prepared by diluting a silicone hard coat agent (Surcoat (trademark) B16N, manufactured by Doken Co., Ltd., solid content concentration: 45% by mass) with 1-propanol to a solid content concentration of 30% by mass.

(Preparation of solution for corrosion prevention layer)
To the anchor layer solution, glycol dimercaptoacetate was further added as a corrosion inhibitor in an amount of 0.3 g / m ² at a thickness of 50 nm after coating to prepare a solution for corrosion prevention layer.

(Preparation of adhesive layer solution)
Polyester (registered trademark) SP181 (polyester resin, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Super Becamine (registered trademark) J-820 (melamine resin, manufactured by DIC Corporation), and TDI (toluene diisocyanate) based isocyanate. 2,4-tolylene diisocyanate, 1,6-hexamethylene diisocyanate, which is an HMDI-based isocyanate, so that the mixing ratio is 20: 1: 1: 2 (solid content mass ratio) and the solid content concentration is 10% by mass. The solution for adhesive layer was prepared by mixing in toluene.

(Production of light reflecting film)
An anchor layer having a thickness (dry film thickness) of 0.05 μm (50 nm) is formed by applying the anchor layer solution on one surface of the resin base material 2 with a bar coater and drying at 100 ° C. for 2 minutes. did. Further, a silver reflective layer having a thickness of 0.1 μm (100 nm) was formed as a light reflective layer on the anchor layer by a vacuum deposition method. After that, the solution for corrosion prevention layer is coated on the silver reflective layer with a bar coater and dried at 100 ° C. for 2 minutes to prevent corrosion with a thickness (dry film thickness) of 0.05 μm (50 nm). A layer was formed. Next, the ultraviolet ray absorbing layer solution is applied to the surface of the resin base material 2 opposite to the surface on which the anchor layer is formed with a bar coater and dried at 80 ° C. for 2 minutes to obtain a thickness (dry). A film thickness of 30 μm ultraviolet absorbing layer was formed. Thereafter, the hard coat layer solution was coated on the ultraviolet absorbing layer with a bar coater and dried at 100 ° C. for 2 minutes to form a hard coat layer having a thickness of 3 μm. Thereafter, the adhesive layer solution is applied onto the corrosion prevention layer with a bar coater, dried at 80 ° C. for 2 minutes to form an adhesive layer, and then the adhesive layer and the resin substrate 1 are bonded together. did. At this time, the thickness (dry film thickness) of the adhesive layer was adjusted to 30 μm by adjusting the coating flow rate. And the winding tension | tensile_strength was set to 150 N and it wound up on a 6-inch diameter core, and the light reflection film of Example 1 was completed.

(Example 2)
A light reflecting film of Example 2 was produced in the same manner except that the thickness of the ultraviolet absorbing layer of Example 1 was changed to 5 μm.

Example 3
A light reflecting film of Example 3 was produced in the same manner except that the thickness of the ultraviolet absorbing layer of Example 1 was 10 μm.

Example 4
A light reflecting film of Example 4 was produced in the same manner except that the thickness of the ultraviolet absorbing layer of Example 1 was 20 μm.

(Example 5)
A light reflecting film of Example 5 was produced in the same manner except that the thickness of the adhesive layer of Example 4 was 3 μm.

(Example 6)
A light reflecting film of Example 6 was produced in the same manner except that the thickness of the adhesive layer of Example 4 was 10 μm.

(Example 7)
A light reflecting film of Example 7 was produced in the same manner except that the thickness of the adhesive layer of Example 4 was 20 μm.

(Comparative Example 1)
A light reflecting film of Comparative Example 1 was produced in the same manner except that the ultraviolet absorbing layer of Example 1 was not formed and the winding tension was changed to 250N.

(Comparative Example 2)
A light reflecting film of Comparative Example 2 was produced in the same manner except that the drying after applying the solution for the corrosion preventing layer of Example 1 with a bar coater was changed to 50 ° C. for 3 minutes.

(Comparative Example 3)
A light reflecting film of Comparative Example 3 was produced in the same manner except that the winding tension of Example 1 was changed to 250N.

(Example 8)
As the resin substrate 2, the anchor layer solution, the ultraviolet absorbing layer solution, the hard coat layer solution, and the corrosion prevention layer solution, the same ones as in Example 1 were used.

(Production of light reflecting film)
An anchor layer having a thickness (dry film thickness) of 0.05 μm (50 nm) is formed by applying the anchor layer solution on one surface of the resin base material 2 with a bar coater and drying at 100 ° C. for 2 minutes. did. Furthermore, a silver reflective layer having a thickness of 100 nm was formed as a light reflective layer on the anchor layer by a vacuum deposition method. After that, the solution for corrosion prevention layer is coated on the silver reflective layer with a bar coater and dried at 100 ° C. for 2 minutes to prevent corrosion with a thickness (dry film thickness) of 0.05 μm (50 nm). A layer was formed. Next, the ultraviolet absorbing layer solution was applied on the corrosion prevention layer with a bar coater and dried at 80 ° C. for 2 minutes to form an ultraviolet absorbing layer having a thickness (dry film thickness) of 20 μm. Thereafter, the hard coat layer solution was coated on the ultraviolet absorbing layer with a bar coater and dried at 100 ° C. for 2 minutes to form a hard coat layer having a thickness of 3 μm. And the winding tension | tensile_strength was set to 150 N and it wound up on a 6-inch diameter core, and the light reflection film of Example 8 was completed.

(Comparative Example 4)
A light reflecting film of Comparative Example 4 was produced in the same manner except that the ultraviolet absorbing layer of Example 8 was not formed and the winding tension was changed to 250N.

  The characteristics of the produced light reflecting film are shown in Table 1 below.

<Evaluation of light reflecting film>
[Image clarity]
Each of the produced light reflecting films was measured from the opposite side of the hard coat layer to the ultraviolet absorbing layer by a method according to ASTM D5767-95 (2012) using RHOPOINT IQ manufactured by RHOPOINT.

[Weather resistance test]
Each of the produced light reflecting films was subjected to ASTM G90-10 Standard Practicing and Performing Outer Natural Heating of Natural Measured at an outdoor exposure test site in Arizona, USA at 33.5 ° N. 112 ° N. Altitude, 610m above sea level. Exposure to sunlight for 6 months.

[Evaluation of adhesion (cross-cut test)]
After the weather resistance test, a cross-cut test based on JIS K 5600-5-6: 1999 was performed. Specifically, 11 cuts were made vertically and horizontally at intervals of 1 mm on the surface side on which the hard coat layer was formed, and 100 1 mm square grids were produced. A cellophane tape was affixed on this, peeled off quickly at an angle of 90 degrees, the number of grids remaining without peeling was measured, and the evaluation of adhesion between the resin substrate and the ultraviolet shielding layer was evaluated according to the following criteria. . In addition, the evaluation judged that 4 or more were practical characteristics.

5: No separation is observed 4: The number of peeled grids is 1 or more and 5 or less 3: The number of peeled grids is 6 or more and 10 or less 2: Stripped grids The number is 11 or more and 20 or less. 1: The number of peeled grids is 21 or more.

[Crack observation]
After the weather resistance test, the number of cracks within 10 cm × 10 cm was confirmed under a fluorescent lamp. In addition, the evaluation judged that 4 or more were practical characteristics.

5: Scratches are not recognized at all 4: 1 cm or more scratches are 1 or more and 5 or less 3: 1 cm or more scratches are 6 or more and 10 or less 2: 1 cm or more The number of scratches is 11 or more and 20 or less. The number of scratches of 1: 1 cm or more is 21 or more.

[Condensation efficiency to the heat collection tube]
After the weather resistance test, a 10 cm × 10 cm light reflecting film was bonded to a 0.8 mm aluminum plate via an adhesive layer, and bent into a concave shape with an opening of 7 cm to prepare a light reflector. Laser light having a wavelength of 532 nm was reflected on the surface of the light reflection film, and the reflected light was detected with a power meter. The light collection efficiency is based on the power meter detection amount of the reflected light of the light reflection film 1 before the weather test, with the power meter detection amount of the reflected light of the light reflection film of Example 1 before the weather resistance test as 100. The amount of reflected light detected by a power meter before and after the weather resistance test of each film was expressed.

  The above evaluation results are shown in Table 1.

  From the results shown in Table 1, the light reflecting films of Examples 1 to 7 of the present invention have an initial light collection efficiency compared to the light reflecting films of Comparative Examples 1 to 3 that do not have the configuration of the present invention. It was confirmed that reduction in light collection efficiency, generation of cracks, and deterioration in adhesion due to aging in an outdoor environment were suppressed.

  Moreover, also in the comparison of the light reflection film of a structure different from Example 1, the light reflection film of Example 8 of this invention is compared with the light reflection film of the comparative example 4 which does not have the structure of this invention. It was confirmed that it has excellent characteristics.

DESCRIPTION OF SYMBOLS 10 Light reflection film 11 Hard coat layer 12 Ultraviolet absorption layer 13 Light reflection layers 14 and 18 Resin base material 15 Adhesive layer 16 Anchor layer 17 Corrosion prevention layer

Claims (6)

  It has at least one resin base material, a hard coat layer, an ultraviolet absorption layer, and a light reflection layer, and the hard coat layer, the ultraviolet absorption layer, and the light reflection layer are arranged in this order, In addition, in a method according to ASTM D5767-95 (2012), the image clarity (DOI) value measured from the side opposite to the ultraviolet absorbing layer of the hard coat layer is 97.0 to 100.0. Reflective film.   The light reflecting film according to claim 1, further comprising an adhesive layer on a side of the light reflecting layer opposite to the ultraviolet absorbing layer.   The light reflecting film according to claim 1 or 2, wherein the adhesive layer has a thickness of 5 to 25 µm.   The light reflecting film according to claim 1, wherein the ultraviolet absorbing layer has a thickness of 10 to 25 μm.   The light reflection body by which the light reflection film of any one of Claims 1-4 is joined to a support base material.   A solar light reflection device comprising the light reflector according to claim 5.