WO2017077810A1

WO2017077810A1 - Light reflecting film

Info

Publication number: WO2017077810A1
Application number: PCT/JP2016/079743
Authority: WO
Inventors: 安藤　達哉
Original assignee: コニカミノルタ株式会社
Priority date: 2015-11-04
Filing date: 2016-10-06
Publication date: 2017-05-11

Abstract

A light reflecting film which comprises: a dielectric multilayer film wherein high-refractive-index layers containing a water-soluble polymer and low-refractive-index layers containing a water-soluble polymer are alternately laminated; and a light stabilizer-containing layer which contains a hindered amine light stabilizer and is arranged adjacent to the dielectric multilayer film.

Description

Light reflection film

The present invention relates to a light reflecting film.

In recent years, there has been an increasing demand for energy-saving measures, and from the viewpoint of reducing the load on cooling equipment, there has been a demand for infrared heat-shielding films that can be attached to window glass of buildings and vehicles to block the transmission of solar heat rays. It is increasing. As one configuration for shielding infrared rays, a dielectric multilayer film in which high refractive index layers and low refractive index layers are alternately laminated is known.

In order to form such a dielectric multilayer film, it is possible to form a layer with a low environmental load while being inexpensive, and therefore a water-based coating liquid containing a water-soluble polymer and inorganic oxide particles is used. The wet coating method was employed (see Patent Document 1 below).

JP2015-125168A

However, the dielectric multilayer film formed using a water-soluble polymer has a problem that, when subjected to a heat resistance test as an acceleration test due to the influence of residual moisture, the haze value increases and transparency is impaired. .

Therefore, an object of the present invention is to provide a light reflecting film having excellent heat resistance even in a configuration having a dielectric multilayer film using a water-soluble polymer.

In order to achieve such an object, the present invention provides a dielectric multilayer film in which a high refractive index layer containing a water-soluble polymer and a low refractive index layer containing a water-soluble polymer are alternately laminated, and a hindered amine-based film. A light reflecting film comprising a light stabilizer and a light stabilizer-containing layer provided adjacent to the dielectric multilayer film.

According to the present invention, it is possible to provide a light reflecting film excellent in heat resistance while having a configuration including a dielectric multilayer film using a water-soluble polymer.

It is a cross-sectional schematic diagram which shows the structure of the light reflection film of 1st Embodiment. It is a cross-sectional schematic diagram which shows the structure of the light reflection film of 2nd Embodiment. It is a cross-sectional schematic diagram which shows the structure of the light reflection film of 3rd Embodiment.

Hereinafter, first to third embodiments relating to a light reflecting film to which the present technology is applied will be described. In addition, in each embodiment, the same code | symbol is attached | subjected to the same component and the overlapping description is abbreviate | omitted.

<< First Embodiment >>
FIG. 1 is a schematic cross-sectional view for explaining the configuration of the light reflecting film of the first embodiment. The light reflecting film 1 of the first embodiment shown in this figure is used by being attached to equipment 100 that is exposed to sunlight for a long period of time, such as an outdoor window of a building or an automobile window. Such a light reflecting film 1 includes a dielectric multilayer film 13 in which low-refractive index layers 13L and high-refractive index layers 13H are alternately stacked on one main surface of a resin base material 11, and the dielectric multilayer film. 13 and a light stabilizer-containing layer 15 provided adjacent to 13. Further, the light reflecting film 1 may include an adhesive layer 17 on the light stabilizer-containing layer 15, and is used by being attached to the equipment 100 through the adhesive layer 17.

The optical characteristics of such a light reflecting film 1 are such that the transmittance in the visible light region shown in JIS R3106-1998 is 50% or more, preferably 75% or more, more preferably 85% or more. Further, if the light reflecting film 1 is, for example, a near-infrared shielding film, it is preferable that the light reflecting film 1 has a region where the reflectance exceeds 50% in a wavelength region of 900 nm to 1400 nm. In addition, below, embodiment is described as this light reflection film 1 being a heat ray reflective film which reflects near infrared rays. However, the light reflecting film 1 is not limited to being a near-infrared shielding film, and may be a film that reflects and shields infrared rays and ultraviolet rays, and has a reflectance in each wavelength region of 50. It is assumed that the film thickness and the constituent material of each layer are set so as to exceed%.

Hereinafter, the detailed configuration of the light reflecting film 1 will be described in the order of the dielectric multilayer film 13, the light stabilizer-containing layer 15, the adhesive layer 17, and the resin base material 11, and finally the method for manufacturing the light reflecting film 1 will be described. To do.

<Dielectric multilayer film 13>
The dielectric multilayer film 13 has a configuration in which a high refractive index layer 13H containing a water-soluble polymer and a low refractive index layer 13L containing a water-soluble polymer are alternately laminated, and the high refractive index layer 13H and the low refractive index layer 13L. It has at least one laminated body with the rate layer 13L. Note that the “high refractive index layer” and the “low refractive index layer” are layers having a refractive index difference between them, and when comparing the refractive index difference between two adjacent layers, the layer having the higher refractive index is selected. The high refractive index layer 13H is used, and the lower layer is the low refractive index layer 13L.

The dielectric multilayer film 13 may be a laminated body in which the high refractive index layers 13H and the low refractive index layers 13L are alternately laminated, and the number of these laminated layers is not limited. The number of layers of the high refractive index layer 13H and the low refractive index layer 13L is, for example, in the range of 10 to 50 layers, preferably 13 to 39 layers. If the number of laminated layers is 10 or more, a desired infrared reflectance is obtained, and if it is 13 or more, a higher infrared reflectance is obtained and the heat shielding effect is improved. Further, if the number of laminated layers is 50 or less, the dielectric multilayer film 13 is excellent in that sufficient weather resistance can be obtained such that the dielectric multilayer film 13 is difficult to break and the edge peeling can be suppressed. Furthermore, if the number of laminated layers is 39 or less, high weather resistance can be obtained, for example, cracking of the dielectric multilayer film 13 and prevention of peeling off of the end portion can be prevented.

Further, in the dielectric multilayer film 13, the lowermost layer on the resin substrate 11 side and the outermost layer on the light stabilizer-containing layer 15 side may be either the high refractive index layer 13H or the low refractive index layer 13L. However, when the lowermost layer and the outermost layer are the low refractive index layer 13L, the adhesion to the adjacent layer (for example, the resin base material 11) in the lowermost layer is improved, and the dielectric multilayer film 13 is formed by coating. It is easy to improve the blowing resistance of the outermost layer.

The dielectric multilayer film 13 can increase the infrared reflectance with a smaller number of layers as the difference in refractive index between the adjacent high refractive index layer 13H and low refractive index layer 13L increases. Accordingly, the high refractive index layer 13H preferably has a higher refractive index. The refractive index of the high refractive index layer 13H is preferably 1.70 to 2.50, more preferably 1.80 to 2.20, and still more preferably 1.90 to 2.20. The low refractive index layer 13L preferably has a lower refractive index. The refractive index of the low refractive index layer 13L is preferably 1.10 to 1.60, more preferably 1.30 to 1.55, and still more preferably 1.30 to 1.50.

In the laminate composed of the high refractive index layer 13H and the low refractive index layer 13L, the refractive index difference is preferably 0.1 or more in at least one pair of the adjacent high refractive index layer 13H and low refractive index layer 13L. 0.2 or more, more preferably 0.25 or more. In the case where the dielectric multilayer film 13 includes a plurality of high refractive index layers 13H and low refractive index layers 13L, it is preferable that the refractive index difference is within the above-described preferable range in all layers. However, the outermost layer and the lowermost layer of the dielectric multilayer film 13 may have a configuration outside the above preferred range. The refractive index difference and the necessary number of layers as described above can be calculated using commercially available optical design software.

The dielectric multilayer film 13 as described above contains metal oxide particles in addition to the water-soluble polymer if the high refractive index layer 13H. In addition, the low refractive index layer 13L contains inorganic fine particles as required in addition to the water-soluble polymer. Since the high refractive index layer 13H and the low refractive index layer 13L contain these particles, the refractive index can be easily adjusted. Therefore, the difference in refractive index between the high refractive index layer 13H and the low refractive index layer 13L can be increased, and the number of stacked layers can be reduced to make the dielectric multilayer film 13 thinner. Further, by reducing the number of layers, productivity can be improved and a decrease in transparency due to scattering at the stack interface can be suppressed.

In such a dielectric multilayer film 13, a mixed layer in which components constituting each layer are mixed may be formed at the interface between the high refractive index layer 13H and the low refractive index layer 13L. When such a mixed layer exists, the high refractive index layer 13H includes a set of portions in which the components constituting the high refractive index layer 13H are 50% by mass or more in the mixed layer, and the low refractive index layer A set of portions where the component constituting 13L exceeds 50 mass% is included in the low refractive index layer 13L.

In addition, the dielectric multilayer film 13 as described above is formed by controlling the refractive index and the film thickness of each of the high refractive index layer 13H and the low refractive index layer 13L constituting the dielectric multilayer film 13, thereby enabling visible light and near red light. It is assumed that the reflectance and transmittance of a specific wavelength such as external light are adjusted.

Hereinafter, the detailed configuration of the dielectric multilayer film 13 includes the water-soluble polymer contained in the dielectric multilayer film 13, other materials, metal oxide particles contained in the high refractive index layer 13H, and the low refractive index layer 13L. The inorganic fine particles contained in will be described in the order.

[Water-soluble polymer (dielectric multilayer film 13)]
The water-soluble polymer contained in the dielectric multilayer film 13 functions as a binder for the high refractive index layer 13H and the low refractive index layer 13L. The water-soluble polymer contained in the high refractive index layer 13H and the water-soluble polymer contained in the low refractive index layer 13L may be the same component or different components but different components. Are preferred.

Examples of the water-soluble polymer contained in the dielectric multilayer film 13 include polyvinyl alcohol and its derivatives (polyvinyl alcohol resin), gelatin, thickening polysaccharides, and the like. From the viewpoints of coating unevenness and film thickness uniformity (haze), a polyvinyl alcohol resin is preferable. Examples of the polyvinyl alcohol resin include various modified polyvinyl alcohols in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate. These water-soluble polymers may be used alone or in combination of two or more.

Polyvinyl alcohol obtained by hydrolyzing vinyl acetate preferably has an average degree of polymerization of 1000 or more, and particularly preferably has an average degree of polymerization of 1500 to 5000. The degree of saponification is preferably 70 to 100 mol%, particularly preferably 80 to 99.9 mol%. As such polyvinyl alcohol, for example, JP-45 (degree of polymerization 4500, degree of saponification 88 mol%) manufactured by Nippon Vinegar Poval can be used.

Examples of the modified polyvinyl alcohol include (a) anion-modified polyvinyl alcohol, (b) nonion-modified polyvinyl alcohol, (c) cation-modified polyvinyl alcohol, (d) ethylene-modified polyvinyl alcohol, and (e) a vinyl alcohol-based polymer. In addition, vinyl acetate resin (for example, “Exeval” manufactured by Kuraray Co., Ltd.), polyvinyl acetal resin obtained by reacting polyvinyl alcohol with aldehyde (for example, “S Lecque” manufactured by Sekisui Chemical Co., Ltd.), silanol-modified polyvinyl having silanol group Alcohol (for example, “R-1130” manufactured by Kuraray Co., Ltd.), modified polyvinyl alcohol resin having an acetoacetyl group in the molecule (for example, “Gosefimer (registered trademark) Z / WR series” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) Etc. are also included in the modified polyvinyl alcohol. Among these, the above (a) to (e) will be described.

Examples of (a) anion-modified polyvinyl alcohol include polyvinyl alcohol having an anionic group described in JP-A-1-206088, JP-A-61-237681 and JP-A-63-30779. Examples thereof include a copolymer of vinyl alcohol and a vinyl compound having a water-soluble group, and a modified polyvinyl alcohol having a water-soluble group described in JP-A-7-285265.

(B) Nonionic modified polyvinyl alcohol includes, for example, a polyvinyl alcohol derivative obtained by adding a polyalkylene oxide group described in JP-A-7-9758 to a part of vinyl alcohol, and a hydrophobic compound described in JP-A-8-25795. A block copolymer of a vinyl compound having a reactive group and vinyl alcohol, a silanol-modified polyvinyl alcohol having a silanol group, and a reactive group-modified polyvinyl alcohol having a reactive group such as an acetoacetyl group, a carbonyl group, or a carboxyl group. .

(C) As the cation-modified polyvinyl alcohol, for example, a primary to tertiary amino group or a quaternary ammonium group described in JP-A-61-10483 is contained in the main chain or side chain of the polyvinyl alcohol. It can be obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate.

Examples of the ethylenically unsaturated monomer having a cationic group include trimethyl- (2-acrylamido-2,2-dimethylethyl) ammonium chloride and trimethyl- (3-acrylamido-3,3-dimethylpropyl) ammonium chloride. N-vinylimidazole, N-vinyl-2-methylimidazole, N- (3-dimethylaminopropyl) methacrylamide, hydroxylethyltrimethylammonium chloride, trimethyl- (2-methacrylamidopropyl) ammonium chloride, N- (1, And 1-dimethyl-3-dimethylaminopropyl) acrylamide. The ratio of the cation-modified group-containing monomer of the cation-modified polyvinyl alcohol is preferably 0.1 to 10 mol%, more preferably 0.2 to 5 mol%, relative to vinyl acetate.

(D) As the ethylene-modified polyvinyl alcohol, for example, those described in JP2009-107324A, JP2003-248123A, JP2003-342322A, and the like can be used. Alternatively, commercially available products such as EXEVAL (trade name: manufactured by Kuraray Co., Ltd.) may be used.

(E) Examples of the vinyl alcohol polymer include EXEVAL (trade name: manufactured by Kuraray Co., Ltd.) and Nichigo G polymer (trade name: manufactured by Nippon Synthetic Chemical Industry Co., Ltd.).

The weight average molecular weight of the above-mentioned polyvinyl alcohol resin is preferably 1,000 to 200,000, more preferably 3000 to 60,000. In addition, the value measured by the static light scattering method, the gel permeation chromatograph method (GPC), TOFMASS, etc. can be employ | adopted for the value of a "weight average molecular weight". When the weight average molecular weight of the water-soluble polymer is within the above range, the application method can be applied and the productivity can be improved.

The content of the water-soluble polymer in the dielectric multilayer film 13 is 5 to 75% by mass with respect to the total solid content of the high refractive index layer 13H and the low refractive index layer 13L constituting the dielectric multilayer film 13. It is preferably 10 to 70% by mass. When the content of the water-soluble polymer is 5% by mass or more, when a high refractive index layer is formed by a wet film forming method, the transparency of the film surface is disturbed when the coating film obtained by coating is dried. Can be prevented. On the other hand, when the content of the water-soluble polymer is 75% by mass or less, it is preferable when the metal oxide particles are contained in the high refractive index layer 13H and when the inorganic fine particles are contained in the low refractive index layer 13L. Content.

In addition, content of water-soluble polymer is calculated | required from the residual solid content of the evaporation-drying method. Specifically, the heat ray shielding film is immersed in hot water at 95 ° C. for 2 hours, and the remaining film is removed, and then the hot water is evaporated, and the amount of the obtained solid matter is made the water-soluble high molecular weight. At this time, when one peak is observed in each of the regions of 1700 to 1800 cm ⁻¹ , 900 to 1000 cm ⁻¹ , and 800 to 900 cm ^{−1 in} the IR (infrared spectroscopy) spectrum, the water-soluble polymer is polyvinyl alcohol. It can be determined that

[Other materials (dielectric multilayer film 13)]
In each layer constituting the dielectric multilayer film 13, a curing agent can be used in order to cure the water-soluble polymer. Curing agents include boric acid and its salts, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidylcyclohexane, N, N-diglycidyl-4-glycidyloxyaniline, sorbitol polyglycidyl Ether, glycerol polyglycidyl ether, etc., aldehyde curing agents (formaldehyde, glyoxal, etc.), active halogen curing agents (2,4-dichloro-4-hydroxy-1,3,5, -s-triazine, etc.), active vinyl Examples of such compounds include 1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, aluminum alum and borax. The content of the curing agent in the refractive index layer is preferably 1 to 10% by mass with respect to the solid content of the refractive index layer.

Further, each layer constituting the dielectric multilayer film 13 may contain a surfactant for adjusting the surface tension during coating film formation. Here, an anionic surfactant, a nonionic surfactant, an amphoteric surfactant, or the like can be used as the surfactant. As the surfactant, an anionic surfactant is preferably used, and one containing a hydrophobic group having 8 to 30 carbon atoms and a sulfonic acid group or a salt thereof in one molecule is preferable. The content of the surfactant in the high refractive index layer is preferably 0.01 to 5% by mass with respect to the solid content of the high refractive index layer. As the surfactant, for example, Newcol series (manufactured by Nippon Emulsifier Co., Ltd.) can be used.

[Metal Oxide Particles Contained in High Refractive Index Layer 13H (Dielectric Multilayer Film 13)]
The high refractive index layer 13H preferably includes titanium oxide particles as metal oxide particles, but may be other metal oxide particles. The metal oxide particles contained in the high refractive index layer 13H are, for example, Ti, Li, Na, Mg, Al, Si, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn Rb, Sr, Y, Nb, Zr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, La, Ta, Hf, W, Ir, Tl, Pb, Bi and a rare earth metal One or two or more kinds of metal oxide particles can be used. In the high refractive index layer 13H, one kind of metal oxide particles may be contained, or two or more kinds may be contained.

Specific examples of these metal oxide particles include zirconium oxide, zinc oxide, alumina, colloidal alumina, lead titanate, red lead, yellow lead, zinc yellow, chromium oxide, ferric oxide, iron black, copper oxide, Magnesium oxide, magnesium hydroxide, titanium oxide, strontium titanate, yttrium oxide, hafnium oxide, niobium oxide, tantalum oxide, barium oxide, indium oxide, europium oxide, lanthanum oxide, zircon, tin oxide, and lead oxide, and These double oxides include lithium niobate, potassium niobate, lithium tantalate, and aluminum / magnesium oxide.

Examples of rare earth metal oxides include scandium oxide, yttrium oxide, lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, and erbium oxide. , Thulium oxide, ytterbium oxide, lutetium oxide, and the like can be used.

Among these materials, TiO ₂ , ZnO, and ZrO ₂ are preferable as the metal oxide particles contained in the high refractive index layer 13H. From the viewpoint of stability in the high refractive index layer 13H, TiO ₂ (titanium dioxide sol ) Is more preferable. Of TiO ₂ , rutile type (tetragonal type) is particularly preferable to anatase type because it has low catalytic activity, and thus the weather resistance of 13H and adjacent layers is high and the refractive index is high.

The high refractive index layer 13H preferably has the largest proportion of titanium oxide as metal oxide particles. Preferably, in all the particles, it is preferable to contain 50% by mass or more of titanium oxide, more preferably 70% by mass or more of titanium oxide, and more preferably 80% by mass or more of titanium oxide.

The content of the metal oxide particles in the high refractive index layer 13H is preferably 20 to 80% by mass in the solid content of the high refractive index layer 13H from the viewpoint of heat ray shielding and color unevenness reduction, preferably 30 to It is more preferably 75% by mass, and further preferably 40 to 70% by mass.

Further, the metal oxide particles used for the high refractive index layer 13H may have a structure in which aluminum, silicon, zirconium, or the like is supported on the surface in an island shape having a three-dimensional barrier. For example, the titanium oxide fine particles may be core-shell particles coated with a silicon-containing hydrated oxide. The core-shell particle has a structure in which the surface of metal oxide particles (for example, titanium oxide particles) serving as a core is covered with a shell layer of silicon-containing hydrated oxide. By using such core-shell particles for the high refractive index layer 13H, mixing at the interface between adjacent layers is suppressed by the interaction between the silicon-containing hydrated oxide of the shell layer and the water-soluble resin. Here, the “coating” indicates a state in which the silicon-containing hydrated oxide is attached to at least a part of the surface of the titanium oxide particles. That is, the metal oxide particles (for example, titanium oxide particles) used for the high refractive index layer 13H may be in a state where the surface is completely covered with silicon-containing hydrated oxide, and a part of the surface of the titanium oxide particles. The silicon-containing hydrated oxide may be attached to the substrate.

Since the refractive index of the core-shell particles is affected by the coating amount of the silicon-containing hydrated oxide, it is preferable that a part of the surface of the titanium oxide particles is coated with the silicon-containing hydrated oxide. In the following, such coated titanium oxide core-shell particles are also referred to as “silica-attached titanium dioxide sol”. As a method of coating the titanium oxide particles with the silicon-containing hydrated oxide, a conventionally known method can be used. For example, JP-A-10-158015, JP-A-2000-204301, JP-A-2007-246351. It is possible to apply the method described in the gazette.

The volume average particle diameter of the metal oxide particles used for the high refractive index layer 13H is preferably 100 nm or less, and more preferably 50 nm or less. In particular, since the haze value is low and the visible light transmittance is excellent, the volume average particle diameter is preferably 1 to 30 nm, more preferably 1 to 20 nm.

Here, the volume average particle diameter is an average value obtained by measuring the particle diameters of 1000 arbitrary particles by a method of observing the particles themselves. For the measurement of the particle size, for example, a laser diffraction scattering method, a dynamic light scattering method, or a method of observing a particle image appearing on a cross section or surface of a layer containing particles with an electron microscope is used. And about 1000 arbitrary particles measured by these methods, there are n1, n2,..., Ni, nk particles having particle diameters of d1, d2,. In the existing population, when the volume per particle is vi, the average particle size mv = the value represented by {Σ (vi · di)} / {Σ (vi)} The diameter.

[Inorganic fine particles contained in the low refractive index layer 13L (dielectric multilayer film 13)]
As the inorganic fine particles contained in the low refractive index layer 13L, any of inorganic oxide particles, metal compound particles, and metal oxide particles can be used. Examples of the inorganic oxide particles include silicon dioxide (SiO ₂ ). An example of the metal compound particles is magnesium fluoride (MgF ₂ ). As the metal oxide particles, among the metal oxide particles exemplified as being contained in the high refractive index layer 13H, those having a refractive index lower than that contained in the high refractive index layer 13H are used. Among these, as the inorganic fine particles contained in the low refractive index layer 13L, it is preferable to use silicon dioxide, and it is particularly preferable to use colloidal silica.

The inorganic fine particles contained in the low refractive index layer 13L preferably have an average particle size of 3 to 100 nm. The average particle size (particle size in the dispersion state before coating) of the inorganic fine particles dispersed in the primary particle state is more preferably 3 to 50 nm, and further preferably 3 to 40 nm. It is particularly preferably 3 to 20 nm, and most preferably 4 to 10 nm. Moreover, as an average particle diameter of secondary particle | grains, it is preferable from a viewpoint with few hazes and excellent visible light transmittance | permeability that it is 30 nm or less. The average particle diameter of the inorganic fine particles in the low-refractive index layer 13L is determined by observing the particles themselves or the particles appearing on the cross section or surface of the low-refractive index layer 13L with an electron microscope. The particle size is measured and determined as a simple average value (number average). Here, the particle size of each particle is a circle diameter (area circle equivalent diameter) when a circle having an area equal to the projected area of the particle is assumed.

The content of the inorganic fine particles in the low refractive index layer 13L is preferably 5 to 70% by mass with respect to the solid content of the low refractive index layer 13L from the viewpoint of refractive index, and is 10 to 50% by mass. More preferably.

<Light stabilizer containing layer 15>
The light stabilizer-containing layer 15 is a layer containing a hindered amine light stabilizer and is provided adjacent to the dielectric multilayer film 13. The light stabilizer-containing layer 15 preferably contains an ultraviolet absorber, and includes a light stabilizer, an ultraviolet absorber, a binder, and other materials as necessary. Hereinafter, these details will be described in order.

[Hindered amine light stabilizer (light stabilizer containing layer 15)]
As the hindered amine light stabilizer contained in the light stabilizer-containing layer 15, for example, an [NR] type in which an organic group (R) is directly bonded to a nitrogen atom (N) of a piperidine ring is used. Further, a [NOR] type in which an organic group (R) is bonded to a nitrogen atom (N) of a piperidine ring via an oxygen atom (O) is used. Further, an [NH] type in which a hydrogen atom (H) is bonded to a nitrogen atom (N) of the piperidine ring is used.

Among these, the [NR] type or [NOR] type hindered amine light stabilizer is a slow-acting, low-deactivation type, and from the viewpoint of long-term durability, [NR] type or [NOR] type It is preferable to use a hindered amine light stabilizer.

The light stabilizer-containing layer 15 may contain a [NH] type hindered amine stabilizer together with at least one of [NR] type and [NOR] type hindered amine stabilizers. Thus, the [NH] type hindered amine stabilizer provides an initial ultraviolet deterioration suppressing effect, and at least one of the [NR] type and [NOR] type hindered amine stabilizers provides a long-term persistence of the ultraviolet deterioration suppressing effect. The light stabilizer-containing layer 15 can be constructed.

Hereinafter, each type of hindered amine light stabilizer will be described.

-[NR] type hindered amine light stabilizer-
As the [NR] type hindered amine light stabilizer, a conventionally known one can be used. For example, it has at least one piperidine ring structure represented by the following formula (1) in the molecule.

Here, in formula (1), R ¹ is an organic group in which a carbon atom is directly bonded to the nitrogen atom [N] of the piperidine ring, and as an example, methylene having 1 or more carbon atoms and at least one or more methylene atoms It is a functional group containing a group or a compound group having this functional group. Examples of such a compound group include an alkyl group, and also include oligomers and polymers.

As a commercial product of such an [NR] type hindered amine light stabilizer, “Tinuvin 144” (trade name) manufactured by BASF is exemplified.

-[NOR] type hindered amine light stabilizer-
As the [NOR] type hindered amine light stabilizer, a conventionally known one can be used. For example, it has at least one piperidine ring structure represented by the following formula (2) in the molecule.

In Formula (2), R ¹ is an organic group bonded to the nitrogen atom [N] of the piperidine ring via an oxygen atom [O]. As an example, R ¹ has 1 or more carbon atoms and at least 1 or more carbon atoms. It is a functional group containing a methylene group or a compound group having this functional group. Such compound groups include oligomers and polymers, and specifically include alkyl groups such as propyl groups.

As a commercially available product of such a [NOR] type hindered amine light stabilizer, “Tinuvin 123” (trade name) manufactured by BASF is exemplified.

-[NH] type hindered amine light stabilizer-
As the [NH] type hindered amine light stabilizer, a conventionally known one can be used. For example, it has at least one piperidine ring structure represented by the following formula (3) in the molecule.

As a commercially available product of such an [NH] type hindered amine light stabilizer, “CHIMASSORB 944” (trade name) manufactured by BASF is exemplified.

-Content of hindered amine light stabilizer-
The light stabilizer-containing layer 15 preferably contains 0.05 to 10% by mass of the above-mentioned hindered amine light stabilizer as a total content.

[Ultraviolet absorber (light stabilizer containing layer 15)]
The ultraviolet absorber contained in the light stabilizer-containing layer 15 is not particularly limited, but preferably contains an ultraviolet absorber A having an absorption region at a wavelength of 380 to 400 nm. Moreover, you may contain the several ultraviolet absorber which has an absorption area | region in a different wavelength range for the purpose of absorbing the ultraviolet of a wider wavelength range. For this reason, an ultraviolet absorber B having an absorption region on the shorter wavelength side than the wavelength of 380 to 400 nm may be further included. Thus, by including the ultraviolet absorber in the light stabilizer-containing layer 15, not only the heat resistance of the light stabilizer-containing layer 15 but also the light resistance can be ensured.

-UV absorber A-
Examples of the ultraviolet absorber A having an absorption region at a wavelength of 380 to 400 nm include indole compounds, azomethine compounds, coumarin compounds, and merocyanine compounds. The light stabilizer-containing layer 15 preferably contains one or more of these ultraviolet absorbers A.

Hereinafter, preferred forms of the indole compound, the azomethine compound, the coumarin compound, and the merocyanine compound of the ultraviolet absorber A will be described.

(Indole compound)
The indole compound is a compound having an indole skeleton represented by the following formula (4).

The indole compound contained in the light stabilizer-containing layer 15 is preferably a compound represented by the following formula (5).

In Formula (5), R ¹ is an alkyl group having 1 to 10 carbon atoms or an aralkyl group having 7 to 10 carbon atoms. R ² is an alkyl group having 1 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, or an ester group. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a butyl group, and a 2-ethylhexyl group. An example of the aralkyl group having 7 to 10 carbon atoms is a phenylmethyl group.

(Azomethine compound)
As the azomethine compound contained in the light stabilizer-containing layer 15, a compound having an azomethine skeleton represented by the following formula (6) is preferable.

In the formula (6), R ¹ and R ² are a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkoxy group, a hydroxyl group, an amino group, a carboxyl group, and a heterocyclic compound, respectively, and R ′ is a halogen compound Atoms, alkyl groups, aryl groups, alkoxy groups, hydroxyl groups, amino groups, carboxyl groups, and heterocyclic compounds.

The azomethine compound contained in the light stabilizer-containing layer 15 is preferably a compound having a structure represented by the following formula (7).

(Coumarin compound)
The coumarin compound contained in the light stabilizer-containing layer 15 is a compound having a coumarin skeleton represented by the following formula (8).

Preferred examples of the coumarin compound contained in the light stabilizer-containing layer 15 include 7-diethylamino-4-methyl-chromen-2-one, 7-diethylamino-4a, 8a-dihydro-chromen-2-one, 7- Diethylamino-3-thiophen-2-yl-chromen-2-one, 7-dimethylamino-2-oxo-2H-chloromen-3-carbonitrile, 3- (1H-benzimidazol-2-yl) -7-diethylamino -Chromen-2-one, 1,1,6,6,8-pentamethyl-2,3,5,6-tetrahydro-1H, 4H-11-oxa-3a-aza-benzo [de] anthraphen-10- ON etc. are mentioned.

(Merocyanine compound)
A preferred example of the merocyanine compound contained in the light stabilizer-containing layer 15 is 1,3-dimethyl-5- [2- (3-methyl-oxadolidin) -ethylidene] -pyrimidine-2,4,6- Trione, 1,3-dimethyl-5- [2- (1-methyl-pyrrolidin-2-ylidene) -ethylidene] -pyrimidine-2,4,6-trione, 1,3-dimethyl-5- [2- ( 3-methyl-thiazolidin-2-ylidene) -ethylidene] -pyrimidine-2,4,6-trione, 3-ethyl-5- [2- (1-methyl-pyrrolidin-2-ylidene) -ethylidene] -2- Thioxo-oxazolidin-4-one, 3-ethyl-5- [2- (3-methyl-thiazolidin-2-ylidene) -ethylidene] -2-thioxo-oxazolidin-4-one, 1 3-dimethyl-5- [2- (1-methyl-pyrrolidin-2-ylidene) -ethylidene] -2-thioxo-imidazolin-4-one, [5- [2- (3-methyl-thiazolidin-2-ylidene] ) -Ethylidene] -4-oxo-2-thioxo-thiazolidin-3-yl] -acetyl acid, 3-ethyl-5- [2- (3-methyl-thiazolidin-2-ylidin) -ethylidene] -2-thioxo -Thiazolidin-4-one, [5- [1-methyl-2- (3-methyl-thiazolidin-2-ylidene) -ethylidene)]-4-oxo-2-thioxo-thiazolidin-3-yl] -acetyl acid Etc.

Of the compounds described above, the indole compounds used in the examples described below are particularly preferably used as the ultraviolet absorber A from the viewpoint of further preventing deterioration of the resin because they can absorb long wavelengths in the ultraviolet region.

-UV absorber B-
As the ultraviolet absorber B having an absorption region on the shorter wavelength side than the wavelength of 380 to 400 nm, a known material generally used as an ultraviolet absorber can be used. Examples of such ultraviolet absorber B include benzotriazole compounds, triazine compounds, and benzophenone compounds. The light stabilizer-containing layer 15 preferably contains one or more of these ultraviolet absorbers B.

-Content of UV absorber-
The light stabilizer-containing layer 15 preferably contains 0.05 to 15% by mass of the ultraviolet absorber as the total content of the above-described ultraviolet absorbers, and preferably 1 to 10% by mass of the ultraviolet absorber. More preferably it is included.

[Binder (light stabilizer containing layer 15)]
The binder constituting the light stabilizer-containing layer 15 is not particularly limited, but urethane-based, silicone-based, acrylic-based, melamine-based, epoxy-based, acrylate-based, polyfunctional (meth) acrylic resins, The water-soluble polymer exemplified for the dielectric multilayer film 13 is used. Among them, an acrylic resin excellent in transparency and durability is preferably used, and thereby the deterioration of the light stabilizer-containing layer 15 can be prevented, so that an increase in haze of the light reflecting film 1 can be suppressed over a long period of time. In addition, the light resistance is improved

[Other materials (light stabilizer containing layer 15)]
Other materials can be added to the light stabilizer-containing layer 15 as necessary, as long as the effects of the light stabilizer-containing layer 15 are not impaired. Other materials include, for example, dispersants, plasticizers, UV stabilizers, surfactants, antioxidants, flame retardants, preservatives, antioxidants, thermal stabilizers, lubricants, fillers, photoinitiators, light Add sensitizers, thermal polymerization initiators, thickeners, coupling agents, antistatic agents, leveling agents, adhesion modifiers, modifiers, or additives such as dyes and pigments to give any color tone May be. These may be used alone or in combination of two or more.

<Adhesion layer 17>
The adhesive layer 17 should just be comprised with the material which has transparent adhesiveness. Examples of the transparent adhesive material include a dry laminating agent, a wet laminating agent, an adhesive, a heat seal agent, and a hot melt agent. Especially, it is preferable that the adhesion layer 17 contains an adhesive as an adhesive material. Examples of the adhesive include acrylic adhesive, silicone adhesive, urethane adhesive, polyvinyl butyral adhesive, polyester resin, polyvinyl acetate resin, nitrile rubber, ethylene-vinyl acetate adhesive, and the like. Can do.

In particular, in applications where the light reflecting film 1 is used by being bonded to a window glass, a method of spraying water on the window and bonding the adhesive layer 17 side of the light reflecting film 1 to a wet glass surface, a so-called water bonding method is used. Preferably used. For this reason, it is preferable to use an acrylic pressure-sensitive adhesive having a low adhesive strength in the presence of water.

The film thickness of the adhesive layer 17 is preferably 10 μm or more and 30 μm or less. By setting the thickness of the adhesive layer 17 to 10 μm or more, it is possible to obtain a necessary adhesive force for the equipment 100 such as glass. Further, by setting the thickness of the adhesive layer 17 to 30 μm or less, when the light reflecting film 1 is peeled off from the equipment 100, it is prevented that cohesive failure occurs in the adhesive layer 17 and the adhesive layer 17 remains on the equipment 100 side. The

In addition, it is preferable that this adhesion layer 17 contains a ultraviolet absorber, and the same thing as the light stabilizer containing layer 15 is used as a contained ultraviolet absorber.

<Resin substrate 11>
The resin substrate 11 is not particularly limited as long as it is a substrate formed of a transparent organic material. Examples of such resin substrate 11 include polyolefin films (polyethylene, polypropylene, etc.), polyester films (polyethylene terephthalate, polyethylene naphthalate, etc.), polyvinyl chloride films, cellulose acetate films, polyimide films, polybutyral films, Examples of the resin base material include a cycloolefin polymer film and a transparent cellulose nanofiber film. Furthermore, two or more layers of these resin base materials can be laminated and used.

As the resin base material 11, it is preferable to use a polyester film. In particular, from the viewpoint of transparency, mechanical strength, dimensional stability among polyester films, dicarboxylic acid components such as terephthalic acid and 2,6-naphthalenedicarboxylic acid, and ethylene glycol and 1,4-cyclohexanedimethanol A film containing a diol component as a main constituent is preferred. Specifically, a polyester mainly composed of polyethylene terephthalate or polyethylene naphthalate, a copolymer polyester composed of terephthalic acid, 2,6-naphthalenedicarboxylic acid and ethylene glycol, and two or more kinds of these polyesters It is preferable that the mixture is a major constituent.

The resin substrate 11 may be an unstretched film or a stretched film. A stretched film is preferable from the viewpoint of strength improvement and thermal expansion suppression.

The thickness of the resin substrate 11 is preferably in the range of 5 μm to 200 μm, more preferably 15 μm to 150 μm.

The resin base material 11 preferably has a visible light region transmittance of 85% or more shown in JIS R3106-1998, and particularly preferably 90% or more. By increasing the transmittance of the resin base material 11, the minimum transmittance of the light reflecting film 1 with a wavelength of 420 nm to 780 nm can be increased.

The resin base material 11 can be manufactured by a conventionally known general method. For example, it can be produced by a known method such as extrusion molding, calendar molding, injection molding, hollow molding, compression molding and the like. In addition, a stretched film may be prepared from an unstretched resin base material using a known method such as uniaxial stretching, tenter-type sequential biaxial stretching, tenter-type simultaneous biaxial stretching, tubular simultaneous biaxial stretching, or the like. it can. The draw ratio in this case can be appropriately selected according to the resin as a raw material, but is preferably 2 to 10 times in the vertical axis direction and the horizontal axis direction.

Further, the resin base material 11 may be subjected to a relaxation treatment or an offline heat treatment in terms of dimensional stability. The relaxation treatment is preferably carried out in any step from the heat setting in the stretching process of the polyester film to the winding in the transversely stretched tenter or after exiting the tenter. The relaxation treatment is preferably performed at a treatment temperature of 80 ° C. to 200 ° C., more preferably a treatment temperature of 100 ° C. to 180 ° C. Further, it is preferable to carry out the treatment at a relaxation rate of 0.1% to 10% in both the longitudinal direction and the width direction, and more preferably, the treatment is performed at a relaxation rate of 2% to 6%. The resin base material 11 subjected to the relaxation treatment is improved in heat resistance by being subjected to off-line heat treatment, and is further improved in dimensional stability.

<The manufacturing method of the light reflection film 1>
Next, the manufacturing method of the light reflection film 1 is demonstrated. The production of the light reflecting film 1 includes the step of forming the dielectric multilayer film 13 on the resin base material 11, the step of forming the light stabilizer-containing layer 15 on the dielectric multilayer film 13, and the step of containing the light stabilizer. Forming an adhesive layer 17 on the layer 15. Hereinafter, these steps will be described in order.

[Process for forming dielectric multilayer 13]
The method for forming the dielectric multilayer film 13 on the resin substrate 11 is not particularly limited, but, for example, a high refractive index layer coating solution and a low refractive index layer coating solution are alternately applied and dried. The method of forming by is mentioned.

The method for preparing the coating solution for the high refractive index layer is not particularly limited, and examples thereof include a method of stirring and mixing a water-soluble polymer, metal oxide particles, a solvent, and other additives added as necessary. It is done. The method for preparing the coating solution for the low refractive index layer is not particularly limited, and examples thereof include a method of stirring and mixing a water-soluble polymer, a solvent, and if necessary, inorganic fine particles and other additives. During the stirring and mixing, the mixing order of the components is not particularly limited, and the components may be sequentially mixed while stirring, or may be mixed and stirred at one time. Each of these coating liquids is adjusted to an appropriate viscosity by adjusting the amount of the solvent.

Here, the solvent for preparing each coating solution is not particularly limited, but it is preferable to use water or a mixed solvent of water and an organic solvent. Further, water is preferable in consideration of environmental aspects due to scattering of the organic solvent.

Examples of the organic solvent used in each coating solution include alcohols such as methanol, ethanol, 2-propanol, and 1-butanol, and esters such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate. And ethers such as diethyl ether, propylene glycol monomethyl ether and ethylene glycol monoethyl ether, amides such as dimethylformamide and N-methylpyrrolidone, and ketones such as acetone, methyl ethyl ketone, acetylacetone and cyclohexanone. These organic solvents may be used alone or in combination of two or more. From the standpoint of environment and ease of operation, the solvent for the coating solution is preferably a mixed solvent of water, methanol, ethanol, and ethyl acetate.

When using a mixed solvent of water and a small amount of an organic solvent, the content of water in the mixed solvent is preferably 80 to 99.9% by mass in the entire mixed solvent, and 90 to 99.5% by mass. More preferably. Here, by setting it as 80 mass% or more, the volume fluctuation | variation by volatilization of a solvent can be reduced, and the operativity of coating-film formation improves. Moreover, by setting it as 99.9 mass% or less, the homogeneity of a coating liquid increases and the physical property of a coating liquid is stabilized.

Next, each prepared coating solution is applied onto the resin substrate 11 and dried. By performing the coating process and the drying process, the dielectric multilayer film 13 can be formed from the coating film.

The coating method is not particularly limited, and any of simultaneous multilayer coating and sequential coating may be used, but simultaneous multilayer coating is preferable from the viewpoint of productivity and the like. As the coating method, for example, a curtain coating method, a slide bead coating method using a hopper described in US Pat. No. 2,761,419, and US Pat. No. 2,761791, an extrusion coating method, and the like are preferably used.

When using the slide bead coating method, the temperature of each coating solution at the time of simultaneous multilayer coating is preferably 25 to 60 ° C., more preferably 30 to 45 ° C. When the curtain coating method is used, a temperature range of 25 to 60 ° C. is preferable, and a temperature range of 30 to 45 ° C. is more preferable.

The viscosity of each coating solution when performing simultaneous multilayer coating is not particularly limited. For example, when the slide bead coating method is used, it is preferably in the range of 5 to 100 mPa · s, more preferably in the range of 10 to 50 mPa · s, in the preferable temperature range of each of the above coating solutions. . When the curtain coating method is used, it is preferably in the range of 5 to 1200 mPa · s, more preferably in the range of 25 to 500 mPa · s, in the preferable temperature range of the coating solution. If it is the range of such a viscosity, simultaneous multilayer coating can be performed efficiently.

Further, when forming the dielectric multilayer film 13 by simultaneous multilayer coating, each coating solution is heated to 30 to 60 ° C., and after the simultaneous multilayer coating of each coating solution is performed on the substrate 11, the formation is performed. The temperature of the coated film is preferably cooled (set) to 1 to 15 ° C. and then dried at 10 ° C. or higher. More preferable drying conditions are a wet bulb temperature of 5 to 50 ° C. and a film surface temperature of 10 to 50 ° C. For example, it is dried by blowing warm air at 80 ° C. for 1 to 5 seconds. Moreover, as a cooling method immediately after application | coating, it is preferable to carry out by a horizontal set system from a viewpoint of the uniformity improvement of the formed coating film.

Here, the above set means that the viscosity of the coating composition is increased by reducing the temperature by applying cold air or the like to the surface of the coating film, and the fluidity of the substances in each layer is reduced or gelled. Means a process. When the finger is pressed against the surface of the coating film, the state in which the finger is no longer attached is defined as the state of completion of setting.

The temperature of the cold air used in the setting process is preferably 0 to 25 ° C, more preferably 5 to 10 ° C. The time for which the coating film is exposed to cold air is preferably 10 to 360 seconds, more preferably 10 to 300 seconds, and further preferably 10 to 120 seconds, although it depends on the transport speed of the coating film.

The time (setting time) from the formation of the coating film to the completion of the setting by applying cold air is preferably within 5 minutes, and more preferably within 2 minutes. The lower limit time is not particularly limited, but is preferably 45 seconds or more. By providing a set time or longer, the components in the layer are sufficiently mixed. On the other hand, by setting the set time short, the interlayer diffusion of the metal oxide particles can be prevented, and a desired refractive index difference can be provided between the high refractive index layer and the low refractive index layer. In the case where high elasticity occurs quickly at the interface between the high refractive index layer and the low refractive index layer, a suitable interface can be formed without providing a setting step.

The set time includes various concentrations such as gelatin, pectin, agar, carrageenan, gellan gum, as well as changing the concentration of water-soluble polymer contained in each coating solution and the concentration of metal oxide particles or inorganic fine particles. It can adjust by adding other components, such as a well-known gelatinizer.

In the case of forming the dielectric multilayer film 13 by the sequential coating method, either the low refractive index layer coating liquid or the high refractive index layer coating liquid heated to 30 to 60 ° C. is used as the base material. After coating on 11 and drying to form a layer, the other coating solution is coated on this layer and dried to form a layer. The dielectric multilayer film 13 is formed by sequentially repeating this process so that the number of layers necessary for expressing desired reflection performance is obtained.

When drying, it is preferable to dry the formed coating film at 30 ° C. or higher. For example, it is preferable to dry in the range of a wet bulb temperature of 5 to 50 ° C. and a film surface temperature of 5 to 100 ° C. (preferably 10 to 50 ° C.). For example, hot air of 40 to 85 ° C. is blown for 1 to 5 seconds. dry. As a drying method, warm air drying, infrared drying, and microwave drying are used. In addition, it is preferable to perform a multi-stage process rather than a single process, and it is more preferable that the temperature of the constant rate drying unit is less than the temperature of the rate-decreasing drying unit. In this case, the temperature range of the constant rate drying section is preferably 30 to 60 ° C., and the temperature range of the decreasing rate drying section is preferably 50 to 100 ° C.

[Step of forming light stabilizer-containing layer 15]
The method for forming the light stabilizer-containing layer 15 on the dielectric multilayer film 13 is not particularly limited. For example, the light stabilizer-containing layer 15 is formed by preparing a coating solution for the light stabilizer-containing layer and then applying and drying the coating solution. The method of doing is mentioned.

The method for preparing the coating solution for the light stabilizer-containing layer is not particularly limited, and the above-described light stabilizer, ultraviolet absorber, binder resin, solvent, and additives added as necessary are stirred. The method of mixing is mentioned. During mixing, the mixing order of each component is not particularly limited, and each component may be sequentially mixed while stirring, or may be mixed and stirred at one time, and the coating may be performed by adjusting the amount of the solvent. The viscosity of the liquid is adjusted appropriately.

The solvent for preparing the coating solution is not particularly limited, and a solvent similar to the solvent used for forming the dielectric multilayer film 13 can be used. It is preferable to use water, an organic solvent, or a mixed solvent thereof. In consideration of environmental aspects due to scattering of the organic solvent, water or a mixed solvent of water and a small amount of an organic solvent is more preferable, and water is particularly preferable.

As the coating method of the coating solution for the light stabilizer-containing layer, a known method can be used. Examples thereof include a die coater method, a gravure roll coater method, a blade coater method, a spray coater method, an air knife coating method, and a dip coating method.

The drying temperature and time of the coating film are not specified, but it is preferable that the amount of the solvent remaining in the light stabilizer-containing layer 15 after drying is small. For this reason, it is preferable to perform drying at a temperature of 50 to 150 ° C. for 10 seconds to 5 minutes. Moreover, when an adhesive is contained in the light stabilizer-containing layer coating solution, since the adhesive has fluidity, curing is necessary to obtain a stable adhesive force. In general, when heated at room temperature for about one week or longer, for example, it is preferably about 50 days at 3 days or longer. In the case of heating, if the temperature is raised too much, the flatness of the substrate 11 may be deteriorated.

[Formation process of adhesive layer 17]
Although the method of forming the adhesion layer 17 on the light stabilizer containing layer 15 is not specifically limited, For example, after adjusting the coating liquid for adhesion layers, the method of forming by apply | coating and drying a coating liquid is mentioned. Alternatively, the pressure-sensitive adhesive layer 17 may be transferred onto the light stabilizer-containing layer 15 after the coating liquid is applied on the release paper and dried. In this case, the release paper may be left as it is on the pressure-sensitive adhesive layer 17 to form the light reflecting film 1 with the release paper.

The method for preparing the coating solution for the pressure-sensitive adhesive layer is not particularly limited, and a material and a solvent necessary for forming the pressure-sensitive adhesive layer 17 may be mixed with stirring, and is the same as the method for preparing the coating solution for the light stabilizer-containing layer described above. Can be done. The coating film can also be dried in the same manner as the formation of the light stabilizer-containing layer 15.

<Effects of First Embodiment>
The light reflecting film 1 according to the first embodiment described above is provided with the light stabilizer layer 15 for improving the light resistance. In particular, the light reflecting film 1 is formed on the dielectric multilayer film 13 containing a water-soluble polymer. A light stabilizer containing layer 15 containing a hindered amine light stabilizer is provided adjacent to the light stabilizer. The light reflecting film 1 having such a configuration was subjected to a heat resistance test as an acceleration test, although it was configured to have a dielectric multilayer film 13 using a water-soluble polymer, as shown in the following examples. Even in this case, it was confirmed that the haze increase was suppressed, transparency could be maintained, and heat resistance was excellent.

Such a mechanism for improving heat resistance is presumed as follows. That is, the dielectric multilayer film 13 containing a water-soluble polymer retains residual moisture therein. For this reason, in the heating environment, the residual moisture moves to the interface of the dielectric multilayer film 13 due to heat and affects adjacent layers. However, the light reflecting film 1 according to the first embodiment remains due to the action of the hindered amine-based light stabilizer in the light stabilizer-containing layer 15 provided adjacent to the dielectric multilayer film 13. It is presumed that the specific resin deterioration near the interface due to the influence of moisture is prevented, thereby suppressing an increase in haze value in a heating environment.

In the first embodiment described above, the configuration in which the light stabilizer-containing layer 15 is provided only on one side of the dielectric multilayer film 13 has been described. However, as a modification of the first embodiment, the dielectric multilayer film 13 A configuration in which the light stabilizer-containing layer 15 is provided on both sides can be presented. In this case, another light stabilizer-containing layer may be provided between the resin substrate 11 and the dielectric multilayer film 13 shown in FIG. According to such a configuration, an effect of further suppressing an increase in haze value can be expected.

<< Second Embodiment >>
FIG. 2 is a schematic cross-sectional view for explaining the configuration of the light reflecting film of the second embodiment. The light reflecting film 2 of the second embodiment shown in this figure is used by being mounted on equipment 100 that is exposed to sunlight for a long period of time, such as an outdoor window of a building or an automobile window. Such a light reflecting film 2 includes a dielectric multilayer film 13 in which low refractive index layers 13L and high refractive index layers 13H are alternately stacked on one main surface of a resin base material 11, and the dielectric multilayer film. 13 is provided with a light stabilizer-containing hard coat layer 21 provided adjacent to 13, and further includes an adhesive layer 17 on the other main surface of the resin substrate 11, and is attached to the equipment 100 via the adhesive layer 17. Used together.

Among these, since the resin base material 11, the dielectric multilayer film 13, and the adhesive layer 17 are the same as those described in the first embodiment, the description thereof is omitted here. Below, the structure of the light stabilizer containing hard-coat layer 21 is demonstrated, and the manufacturing method of the light reflection film 2 is demonstrated.

<Light stabilizer-containing hard coat layer 21>
The light stabilizer-containing hard coat layer 21 is a layer containing a hindered amine light stabilizer as a light stabilizer in the hard coat layer for imparting scratch resistance to the exposed surface of the light reflecting film 2. Therefore, it is provided adjacent to the dielectric multilayer film 13. The light stabilizer-containing hard coat layer 21 may contain an ultraviolet absorber.

Such a light stabilizer-containing hard coat layer 21 is configured to include a hindered amine light stabilizer, and an ultraviolet absorber and other materials as necessary, in the hard coat layer described below. Among these, the same hindered amine light stabilizer and ultraviolet absorber as those described in the first embodiment are used.

The hard coat layer is a layer having a pencil hardness of H to 8H. Particularly preferably, it is in the range of 2H to 6H. The pencil hardness is the pencil hardness specified in JIS K 5400 using the test pencil specified in JIS S 6006 after conditioning the prepared hard coat layer for 2 hours at a temperature of 25 ° C. and a relative humidity of 60%. Measure according to the evaluation method.

The hard coat layer should be formed using an organic hard coat material such as silicone, melamine, epoxy, acrylate, or polyfunctional (meth) acrylic compound, or an inorganic hard coat material such as silicon dioxide. Can do. In particular, since the adhesive strength is high and the productivity is excellent, it is preferable to use a hard coat material of a (meth) acrylate-based or polyfunctional (meth) acrylic-based compound. Here, (meth) acryl refers to acrylic and methacrylic.

Further, in order to obtain high scratch resistance in the hard coat layer, it is preferable that a resin that cures through a crosslinking reaction is a main component. In particular, it is preferable that the hard coat layer is mainly composed of an actinic radiation curable resin. As the actinic radiation curable resin, an ultraviolet curable resin is preferably used, and a commercially available product may be used. Further, when an actinic radiation curable resin is used for the hard coat layer, it is preferable to use a sensitizer having an absorption maximum in the wavelength region of the actinic radiation used when curing the actinic radiation curable resin as an additive. .

The dry film thickness of the hard coat layer is preferably within the range of an average film thickness of 0.1 to 30 μm. Further, it is preferably in the range of 1 to 20 μm, particularly preferably in the range of 3 to 15 μm. When it is 3 μm or more, sufficient durability and impact resistance can be obtained. Moreover, from a viewpoint of flexibility or economical efficiency, 15 micrometers or less are preferable.

In addition, inorganic or organic fine particles may be added to the hard coat layer coating liquid in order to give the hard coat layer an antiglare property and to prevent adhesion with other substances and improve scratch resistance and the like. it can. Moreover, in order to improve the heat resistance of a hard-coat layer, antioxidant with little suppression of photocuring reaction can be used in the coating liquid for hard-coat layers.

<The manufacturing method of the light reflection film 2>
Next, the manufacturing method of the light reflection film 2 is demonstrated. The production of the light reflecting film 2 includes a step of forming a dielectric multilayer film 13 on one main surface of the resin base material 11, a step of forming a light stabilizer-containing hard coat layer 21 on the dielectric multilayer film 13, and And a step of forming an adhesive layer 17 on the other main surface of the resin base material 11. Hereinafter, these steps will be described in order.

[Process for forming dielectric multilayer 13]
A method similar to the method described in the first embodiment is applied to the method for forming the dielectric multilayer film 13 on one main surface of the resin base material 11.

[Step of forming light stabilizer-containing hard coat layer 21]
The method for forming the light stabilizer-containing hard coat layer 21 on the dielectric multilayer film 13 is not particularly limited. For example, after preparing a coating liquid for a hard coat layer, the coating liquid is applied and dried, The method of irradiating actinic rays after drying is mentioned.

The method for preparing the coating solution for the hard coat layer is not particularly limited, and the above-described actinic radiation curable resin, light stabilizer, ultraviolet absorber added as necessary, and further, a solvent and other additives are stirred. The method of mixing is mentioned. During mixing, the mixing order of each component is not particularly limited, and each component may be sequentially mixed while stirring, or may be mixed and stirred at one time, and the coating may be performed by adjusting the amount of the solvent. The viscosity of the liquid is adjusted appropriately.

Solvents for preparing the hard coat layer coating solution include, for example, hydrocarbons (toluene, xylene), alcohols (methanol, ethanol, isopropanol, butanol, cyclohexanol), ketones (acetone, methyl ethyl ketone, methyl isobutyl). Ketones), esters (methyl acetate, ethyl acetate, methyl lactate), glycol ethers, and other organic solvents, or a mixture thereof can be used. The coating liquid for hard coat layer contains 5% by mass of propylene glycol monoalkyl ether (1 to 4 carbon atoms of alkyl group) or propylene glycol monoalkyl ether acetate ester (1 to 4 carbon atoms of alkyl group). As described above, it is preferable to use an organic solvent contained in the range of 5 to 80% by mass.

A known method can be used as a coating method of the coating liquid for the hard coat layer. Examples thereof include a die coater method, a gravure roll coater method, a blade coater method, a spray coater method, an air knife coating method, and a dip coating method. Using these coating methods, it is preferable to form a coating film within a range of a coating film thickness of 0.1 to 100 μm.

The drying temperature and time of the coating film are not specified, but it is preferable that the amount of the solvent remaining in the light stabilizer-containing hard coat layer 21 after drying is small.

The light source for curing the actinic radiation curable resin during or after drying is not particularly limited as long as it is a light source that generates ultraviolet rays. Irradiation conditions vary depending on the light source to be used. For example, the irradiation light quantity can be about 20 to 1200 mJ / cm ² , preferably about 50 to 1000 mJ / cm ² .

[Formation process of adhesive layer 17]
The method for forming the adhesive layer 17 on the other main surface of the resin base material 11 is not particularly limited, and is carried out in the same manner as the adhesive layer 17 forming step described in the first embodiment, and is a light reflecting film with release paper. It may be 2.

<Effects of Second Embodiment>
The light reflecting film 2 of the second embodiment described above is provided with a light stabilizer-containing hard coat layer 21 containing a hindered amine light stabilizer adjacent to the dielectric multilayer film 13 containing a water-soluble polymer. It is a configuration. Even in the light reflecting film 2 having such a configuration, as shown in the following examples, the light reflecting film 2 has a structure having the dielectric multilayer film 13 using a water-soluble polymer. Since it is possible to suppress an increase in haze under the environment, it is possible to maintain transparency.

As a modification of the second embodiment described above, a configuration in which light stabilizer-containing layers are provided on both sides of the dielectric multilayer film 13 can be presented. In this case, the light stabilizer-containing layer 15 (see FIG. 1) having the structure described in the first embodiment is provided between the resin base material 11 and the dielectric multilayer film 13 shown in FIG. be able to. According to such a configuration, an effect of further suppressing an increase in haze value can be expected.

«Third embodiment»
FIG. 3 is a schematic cross-sectional view for explaining the configuration of the light reflecting film of the third embodiment. The light reflecting film 3 of the third embodiment shown in this figure is different from the light reflecting film 1 of the first embodiment described with reference to FIG. 1 in that the light stabilizer containing layer 15 and the adhesive in the light reflecting film 1 are the same. Instead of the layer 17, the light stabilizer-containing adhesive layer 31 is provided. Since the other structure is the same as that of 1st Embodiment, the structure of the light stabilizer containing adhesion layer 31 is demonstrated here.

<Light Stabilizer-Containing Adhesive Layer 31>
The light stabilizer-containing adhesive layer 31 includes a transparent adhesive material, a hindered amine light stabilizer, an ultraviolet absorber, and other materials as necessary.

Among these, as the material having transparent adhesiveness, the same material as the adhesive layer 17 (see FIG. 1) described in the first embodiment can be used, but acrylic adhesive having particularly excellent transparency and durability. It is preferable to use an agent as a binder, whereby it is possible to suppress an increase in haze of the light reflecting film 1 due to further improvement in heat resistance, and it is also possible to improve light resistance.

Further, the same hindered amine light stabilizer and ultraviolet absorber as those described in the first embodiment are used.

<The manufacturing method of the light reflection film 3>
The manufacturing method of the light reflecting film 3 as described above includes the step of forming the dielectric multilayer film 13 on one main surface of the resin base material 11, and the light stabilizer-containing adhesive layer 31 on the dielectric multilayer film 13. Forming. These steps are performed in the same manner as the formation step of the dielectric multilayer film 13 and the formation step of the adhesive layer 17 described in the first embodiment (see FIG. 1). However, in the formation process of the light stabilizer containing adhesion layer 31, the light stabilizer containing adhesion layer coating liquid which further mixed the light stabilizer with the coating liquid for adhesion layers demonstrated in 1st Embodiment. Adjust.

<Effect of the third embodiment>
The light reflecting film 3 of the third embodiment described above is provided with a light stabilizer-containing adhesive layer 31 containing a hindered amine light stabilizer adjacent to the dielectric multilayer film 13 containing a water-soluble polymer. It is a configuration. Even in the light reflection film 3 having such a configuration, as shown in the following examples, the haze increases over a long period of time even though the dielectric multilayer film 13 using the water-soluble polymer is used. Therefore, transparency can be maintained.

In particular, in the light stabilizer-containing adhesive layer 31 provided adjacent to the dielectric multilayer film 13, the glass transition point of the resin is as low as about −80 ° C. to −10 ° C. By containing the light stabilizer in the highly adhesive material, the molecular mobility of the light stabilizer is increased. For this reason, the light stabilizer can act more effectively at the interface between the dielectric multilayer film 13 and the light stabilizer-containing adhesive layer 31. As a result, compared with the configuration of the first embodiment and the second embodiment, it is possible to obtain a high effect of preventing deterioration of the resin due to the influence of residual moisture and suppressing an increase in haze, and thus further improvement of heat resistance Can be achieved.

Also for the third embodiment described above, as a modification thereof, a configuration in which light stabilizer-containing layers are provided on both sides of the dielectric multilayer film 13 can be presented. In this case, the light stabilizer-containing layer 15 (see FIG. 1) having the structure described in the first embodiment is provided between the resin substrate 11 and the dielectric multilayer film 13 shown in FIG. be able to. According to such a configuration, an effect of further suppressing an increase in haze value can be expected.

Next, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented. In the following, first, as a step common to each example and comparative example, a step of forming a dielectric multilayer film on a resin base material will be described, and then a step subsequently performed in each example and comparative example will be described. Individually explained. In addition, in the following Table 1, the structure of the layer containing a light stabilizer in each Example and a comparative example is shown.

<Formation of dielectric multilayer film>
[1. Preparation of coating solution for low refractive index layer]
380 parts by mass of colloidal silica (10% by mass, Snowtex OXS, average particle size of primary particles = 4 to 6 nm, manufactured by Nissan Chemical Industries, Ltd.), 50 parts by mass of boric acid aqueous solution (3% by mass), 300 parts by mass Polyvinyl alcohol (4% by mass, JP-45, polymerization degree: 4500, saponification degree: 88 mol%, manufactured by Nihon Vitamin Pover Co., Ltd.), 3 parts by mass of surfactant (5% by mass, SOFTAZOLINE LSB-R) , Manufactured by Kawaken Fine Chemical Co., Ltd.) in this order at 45 ° C. and mixed. And it finished to 100 mass parts with pure water, and prepared the application for low refractive index layers.

[2. Preparation of coating solution for high refractive index layer]
(2-1. Preparation of silica-attached titanium dioxide sol)
A silica-attached titanium dioxide sol used for the coating solution for the high refractive index layer was prepared as follows. First, 2 parts by mass of pure water was added to 0.5 parts by mass of 15.0% by mass titanium oxide sol (SRD-W, volume average particle diameter: 5 nm, rutile titanium dioxide particles, manufactured by Sakai Chemical Co., Ltd.), and then 90 ° C. Heated to. Next, with respect to the heated solution, 0.5 part by mass of a silicic acid aqueous solution (sodium silicate 4 manufactured by Nippon Kagaku Co., Ltd. diluted with pure water so that the SiO ₂ concentration becomes 0.5 mass%) Were gradually added and mixed, followed by further heat treatment at 175 ° C. for 18 hours in an autoclave. Then, after cooling, by concentration using an ultrafiltration membrane, sol dioxide solid concentration was deposited SiO ₂ of 6 wt% on the surface (hereinafter silica deposition dioxide sol, the volume average particle diameter: 9 nm) to give the It was.

(2-2. Preparation of coating solution for high refractive index layer)
To 113 parts by mass of the silica-attached titanium dioxide sol (20% by mass), 48 parts by mass of an aqueous citric acid solution (1.92% by mass) was added, and ethylene modified polyvinyl alcohol (Kuraray Co., Ltd., EXVAL RS-2117, Ken Degree: 97.5 to 99 mol%, ethylene modification degree: 3.0 mol%, polymerization degree: 1700, viscosity (4%, 20 ° C.): 23.0 to 30.0 [mPa · s], 8 mass%) Was added and stirred, and finally 0.4 parts by weight of a 5% by weight aqueous surfactant solution (Softazoline LSB-R, manufactured by Kawaken Fine Chemical Co., Ltd.) was added to prepare a coating solution for a high refractive index layer. .

[3. Formation of dielectric multilayer film (see FIGS. 1 to 3)]
A 50 μm thick polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., Cosmo Shine A4300) was prepared as the resin substrate 11.

Using a slide hopper coating apparatus, the low refractive index layer coating solution and the high refractive index layer coating solution obtained by the above method are kept at 45 ° C. while being heated to 45 ° C. 11 layers were simultaneously applied (total thickness of dielectric multilayer film: 1.5 μm). At this time, the lowermost layer and the outermost layer were the low refractive index layers 13L, and the other layers were formed such that the low refractive index layers 13L and the high refractive index layers 13H were alternately laminated. The coating amount was adjusted so that the low refractive index layer 13L was 150 nm in each layer and the high refractive index layer 13H was 120 nm in the film thickness after drying. The film thickness was confirmed by cutting the produced laminate (resin substrate 11 and dielectric multilayer film 13) and observing the cut surface with an electron microscope. At this time, when the interface between the two layers could not be clearly observed, the interface was determined by the XPS profile in the thickness direction of TiO ₂ contained in the layer obtained by the XPS surface analyzer.

Immediately after application, it was set by blowing cold air of 5 ° C. At this time, even if the surface was touched with a finger, the time until the finger was lost (set time) was 5 minutes. After completion of the setting, warm air of 80 ° C. was blown and dried to form a dielectric multilayer film 13 consisting of 11 layers on the resin base material 11.

<Example 1 (configuration of FIG. 1)>
On the dielectric multilayer film 13 formed on the resin substrate 11 as described above, the light stabilizer-containing layer 15 and the adhesive layer 17 are further formed as follows to produce the light reflecting film 1. did.

[1. Preparation of coating solution A1 for light stabilizer-containing layer]
To 100 parts by mass of a urethane resin solution (DM-677: manufactured by DIC), 50 parts by mass of toluene and 1 part by mass of [NH] type hindered amine light stabilizer (CHIMASSORB 944, manufactured by BASF) are added and stirred. A coating solution A1 for a light stabilizer-containing layer was prepared.

[2. Formation of light stabilizer-containing layer 15]
A light stabilizer-containing layer 15 having a dry film thickness of 10 μm was formed on the dielectric multilayer film 13 by applying the light stabilizer-containing layer coating solution A1 using a gravure coater and performing a drying treatment. .

[3. Adjustment of adhesive layer coating liquid B]
100 parts by weight of an adhesive (N-2147, manufactured by Nihon Gosei Co., Ltd.), 100 parts by weight of a solvent (ethyl acetate), 1.0 part by weight of an isocyanate curing agent (Coronate HL, manufactured by Tosoh Corporation) are mixed and applied for an adhesive layer. Liquid B was prepared.

[4. Formation of adhesive layer 17]
The adhesive layer coating solution B is applied to the silicone release surface of the release paper (Nakamoto Pax separator NS23MA) with a comma coater so that the dry film thickness is 10 μm, and dried at 90 ° C. for 1 minute. Thus, an adhesive layer 17 was formed. Next, the pressure-sensitive adhesive layer 17 on the release paper was bonded to the light stabilizer-containing layer 15 on the resin base material 11 to produce the light reflecting film 1 of Example 1 with release paper.

<Example 2 to Example 4 (Configuration of FIG. 1)>
In the preparation of the coating solution A1 for the light stabilizer-containing layer described in Example 1, the following example was used except that the following hindered amine light stabilizer was used instead of the [NH] type hindered amine light stabilizer. In the same manner as in Example 1, the light reflecting films 1 of Examples 2 to 4 with release paper were produced.
Example 2 ... [NOR] type: Tinuvin 123 (manufactured by BASF)
Example 3 [NR] type: Tinuvin 144 (manufactured by BASF)
Example 4 ... [NR] type: Tinuvin 292 (BASF)

<Example 5 (configuration of FIG. 1)>
The same as in Example 1 except that the light stabilizer-containing layer coating solution A1 described in Example 1 was changed to a light stabilizer-containing layer coating solution A2 that was prepared as follows using an acrylic resin. Thus, the light reflecting film 1 of Example 5 with release paper was produced.

[Preparation of coating solution A2 for light stabilizer-containing layer]
100 parts by mass of an acrylic resin solution (Acridic A-165: manufactured by DIC), 50 parts by mass of toluene, 50 parts by mass of n-butanol, 1 part by mass of [NR] type hindered amine light stabilizer (Tinuvin 144, manufactured by BASF) The mixture was stirred and mixed to prepare a coating solution A2 for a light stabilizer-containing layer.

<Example 6 (configuration of FIG. 2)>
On the dielectric multilayer film 13 formed on one main surface of the resin base 11 as described above, the light stabilizer-containing hard coat layer 21 is formed as follows. An adhesive layer 17 was formed on the main surface to produce a light reflecting film 2.

[1. Preparation of coating solution C for hard coat layer containing light stabilizer]
UV curable resin (Aronix M-305: manufactured by Toagosei Co., Ltd.), 100 parts by mass of solvent (methyl ethyl ketone), [NR] type hindered amine light stabilizer (Tinuvin 144: manufactured by BASF), 1 part by mass, polymerization initiator (Irgacure 819: manufactured by BASF Japan Ltd.) 5 parts by mass, fluorine-based surfactant (Furgent 650A: manufactured by Neos Co., Ltd.) 0.1 part by mass was added and mixed by stirring to apply a light stabilizer-containing hard coat layer. Liquid C was prepared.

[2. Formation of light stabilizer-containing hard coat layer 21]
On the dielectric multilayer film 13, the light stabilizer-containing coating liquid C for hard coat layer was applied using a gravure coater, and dried at 90 ° C. for 1 minute. Next, using an ultraviolet lamp, ultraviolet rays were applied from the side where the light stabilizer-containing hard coat layer coating liquid C was applied under the conditions of an illuminance of 100 mW / cm ² , an irradiation amount of 0.2 J / cm ² , and an oxygen concentration of 200 ppm. By irradiating, the coating film was cured and the light stabilizer-containing hard coat layer 21 was formed.

[3. Formation of adhesive layer 17]
The adhesive layer coating solution B prepared as described in Example 1 was applied to the silicone release surface of the release paper (Nakamoto Packs separator NS23MA) with a comma coater so that the dry film thickness was 10 μm. The adhesive layer 17 was formed by drying at 90 ° C. for 1 minute. Next, the pressure-sensitive adhesive layer 17 on the release paper was bonded to the other main surface side of the resin base material 11 to prepare the light reflecting film 2 of Example 6 with release paper.

<Example 7 (configuration of FIG. 3)>
On the dielectric multilayer film 13 formed on one main surface of the resin substrate 11 as described above, the light stabilizer-containing adhesive layer 31 was formed as follows to produce the light reflecting film 3.

[1. Adjustment of coating solution D for light stabilizer-containing adhesive layer]
100 parts by weight of an adhesive (N-2147, manufactured by Nihon Gosei Co., Ltd.), 100 parts by weight of a solvent (ethyl acetate), 1 part by weight of [NR] type hindered amine light stabilizer (Tinuvin 144, manufactured by BASF), an isocyanate curing agent 1.0 part by mass (Coronate HL, manufactured by Tosoh Corporation) was stirred and mixed to prepare a coating solution D for the light stabilizer-containing adhesive layer.

[2. Formation of light stabilizer-containing adhesive layer 31]
The light stabilizer-containing adhesive layer coating solution D was applied to the silicone release surface of release paper (Nakamoto Packs separator NS23MA) with a comma coater so that the dry film thickness was 10 μm. The light stabilizer-containing adhesive layer 31 was formed by drying at 1 ° C. for 1 minute. Next, the light stabilizer-containing adhesive layer 31 on the release paper was bonded to the dielectric multilayer film 13 on the resin base material 11, and the light reflecting film 3 of Example 7 with release paper was produced.

<Example 8 (configuration of FIG. 3)>
In the preparation of the light stabilizer-containing adhesive layer coating solution D described in Example 7, a triazine compound (Tinuvin 477, manufactured by BASF) that further serves as an ultraviolet absorber having an absorption region shorter than a wavelength of 380 to 400 nm. Except having added 5 weight part, it carried out similarly to Example 7, and produced the light reflection film 3 of Example 8 with a release paper.

<Example 9 (configuration of FIG. 3)>
In the preparation of the light stabilizer-containing adhesive layer coating solution D described in Example 7, a triazine compound (Tinuvin 477, manufactured by BASF) that further serves as an ultraviolet absorber having an absorption region shorter than a wavelength of 380 to 400 nm. Release paper in the same manner as in Example 7 except that 5 parts by weight and 3 parts by mass of an indole compound (BONASORB 3912, manufactured by Orient Chemical Industries) serving as an ultraviolet absorber having an absorption region at a wavelength of 380 to 400 nm were added. The light reflection film 3 of Example 9 with a mark was produced.

<Comparative Example 1 (see FIG. 3)>
A light-reflective film with release paper was produced in the same manner as in Example 7 except that an adhesive layer containing no light stabilizer was formed instead of the light stabilizer-containing adhesive layer 31 formed in Example 7. did. For the formation of the adhesive layer, the adhesive layer coating solution B described in Example 1 was used, and the adhesive layer was formed in the same manner as the formation of the light stabilizer-containing adhesive layer 31 described in Example 7.

<Comparative Example 2 (see FIG. 3)>
In the formation of the adhesive layer of Comparative Example 1, the triazine compound (Tinuvin 477, manufactured by BASF) 5 serving as an ultraviolet absorber having an absorption region shorter than the wavelength 380 to 400 nm with respect to the adhesive layer coating solution B 5 With release paper as in Comparative Example 1, except that 3 parts by weight of an indole compound (BONASORB 3912, manufactured by Orient Chemical Industries) serving as an ultraviolet absorber having an absorption region at a wavelength of 380 to 400 nm was added. A light reflecting film was prepared.

<Evaluation-1>
About the light reflection film of an Example and a comparative example, the following heat resistance test was done and the haze value before and behind a test was measured as follows. The results are shown in Table 1 below.

[Heat resistance test]
The light reflecting film with the release paper attached thereto was kept in a constant temperature bath at 85 ° C. and 85% RH for 500 hours.

[Measurement of haze value]
The haze was measured using a haze meter (NDH2000 type manufactured by Nippon Denshoku Industries Co., Ltd.), and the average value of 10 optical reflective film samples was calculated. Moreover, the difference ((DELTA) H) of the haze value before and behind a heat resistance test was computed. In addition, as an initial haze value before the heat resistance test of an optical reflection film, it is preferable in it being 1.5% or less. The haze value after the heat resistance test is preferably 3.0% or less.

<Evaluation-2>
About the light reflection film of an Example and a comparative example, the following light resistance test was done, the transmitted light before and behind a test was measured as follows, and the color difference ((DELTA) E) was calculated from the difference. The results are shown in Table 1 below.

[Light resistance test]
The release paper was peeled off from each of the produced light reflecting films and attached to blue glass having a thickness of 3 mm. 100 W / m with respect to each light reflecting film through blue glass using a xenon weather meter (manufactured by Suga Test Instruments Co., Ltd .; emits light very close to sunlight) under the conditions of 30 ° C. and 60% RH. Xenon light having an intensity of ² was irradiated for 1,000 hours.

[Measurement of transmitted light]
Using a spectrophotometer U-4000 type (using an integrating sphere, manufactured by Hitachi, Ltd.), the transmittance of region light having a wavelength of 200 to 2000 nm was measured by a method according to JIS R3106-1998. The smaller the value of the color difference (ΔE) calculated from the difference in transmitted light before and after the light resistance test, the smaller the degree of coloring due to exposure to xenon light.

<Evaluation results>
As shown in Table 1, the haze difference (ΔH) of the light reflecting films of Examples 1 to 9 in which each layer containing a hindered amine light stabilizer is provided as a layer adjacent to the dielectric multilayer film 13 is It can be seen that the haze difference (ΔH) of Comparative Example 1 and Comparative Example 2 which are not configured as described above is suppressed to be lower. This makes it possible to maintain transparency in long-term use by providing a layer containing a hindered amine light stabilizer adjacent to the dielectric multilayer film 13 using a water-soluble polymer. confirmed.

Further, comparing the configurations of Examples 1 to 4 with only the kind of the hindered amine light stabilizer being changed, a slow-acting and low-activation type [NR] type or [NOR] type hindered amine type light is used. The haze difference (ΔH) of Examples 2 to 4 using the stabilizer is suppressed to be lower than the haze difference (ΔH) of Example 1 using the [NH] type hindered amine light stabilizer. I understand that. Thereby, the layer adjacent to the dielectric multilayer film 13 contains a [NR] type or [NOR] type hindered amine light stabilizer as the light stabilizer, thereby further improving the weather resistance. It was confirmed that

Moreover, when the structure which only the binder of the light stabilizer content layer 15 of Example 3 and Example 5 was changed is compared, the light resistance (color change ΔE) of Example 5 using an acrylic resin as a binder is as a binder. It turns out that it is restrained lower than the light resistance (discoloration (DELTA) E) of Example 3 using a urethane-type resin. Thereby, it was confirmed that the layer containing the light stabilizer provided adjacent to the dielectric multilayer film 13 is improved in light resistance by using an acrylic resin as a binder. Moreover, since the initial haze value of Example 5 was restrained lower than the initial haze value of Example 3, it was confirmed that transparency was improved by using an acrylic resin.

In addition, as a layer adjacent to the dielectric multilayer film 13 of Example 6, the evaluation result of the configuration in which the light stabilizer-containing hard coat layer 21 containing a hindered amine-based light stabilizer is provided is as in Example 5. It turns out that it is comparable with the evaluation result of a structure. Thereby, it is not necessary to provide a special layer as a layer containing a hindered amine light stabilizer, and a hindered amine light stabilizer is contained in an existing layer adjacent to the dielectric multilayer film 13. Thus, it was confirmed that the effects of the present invention can be obtained.

Moreover, the evaluation result of the structure which provided the light stabilizer containing adhesion layer 31 containing a hindered amine type light stabilizer as a layer adjacent to the dielectric multilayer film 13 of Example 7 is the structure of Example 5. It can be seen that both the haze difference (ΔH) and the light resistance (discoloration ΔE) are suppressed to be lower than those of the evaluation results. Thereby, the effect which makes the layer containing a hindered amine light stabilizer the adhesive layer which used the adhesive as a binder was confirmed.

Further, comparing the configurations of Example 7 to Example 9 in which only the ultraviolet absorber contained in the light stabilizer-containing adhesive layer 31 was changed, the light resistance of Examples 8 and 9 containing the ultraviolet absorber was compared. It can be seen that (color change ΔE) is suppressed to be lower than the light resistance (color change ΔE) of Example 7 in which no ultraviolet absorber was contained. In addition, it can be seen that the light resistance (discoloration ΔE) of Example 9 containing triazine and indole having different wavelength absorption regions as the UV absorber is particularly low. Thereby, the effect of containing an ultraviolet absorber in the layer adjacent to the dielectric multilayer film 13 and the effect of containing an indole compound as the ultraviolet absorber were confirmed.

DESCRIPTION OF SYMBOLS 1, 2, 3 ... Light reflection film 13 ... Dielectric multilayer film 13H ... High refractive index layer 13L ... Low refractive index layer 15 ... Light stabilizer containing layer 21 ... Light stabilizer containing hard-coat layer 31 ... Light stabilization Agent-containing adhesive layer

Claims

A dielectric multilayer film in which a high refractive index layer containing a water-soluble polymer and a low refractive index layer containing a water-soluble polymer are alternately laminated;
A light reflecting film comprising a hindered amine-based light stabilizer and a light stabilizer-containing layer provided adjacent to the dielectric multilayer film.
The light reflecting film according to claim 1, wherein the high refractive index layer contains rutile type titanium oxide.
The light reflecting film according to claim 1, wherein the hindered amine light stabilizer is a compound in which an organic group is bonded to a nitrogen atom of a piperidine ring directly or via an oxygen atom.
The light reflecting film according to any one of claims 1 to 3, wherein the light stabilizer-containing layer contains an acrylic resin as a binder.
The light reflecting film according to any one of claims 1 to 4, wherein the light stabilizer-containing layer is a light stabilizer-containing adhesive layer using an adhesive as a binder.
The light reflecting film according to any one of claims 1 to 5, wherein the light stabilizer-containing layer contains an ultraviolet absorber.
The light reflecting film according to any one of claims 1 to 6, wherein the light stabilizer-containing layer contains an indole compound as an ultraviolet absorber.