JP7254693B2 - laminate - Google Patents

Description

The present invention relates to laminates.

In order to realize driving support technology for a vehicle, it is necessary to mount a sensor on the vehicle body for detecting information on the outside of the vehicle. Such sensors include LiDAR (Light Detection and Ranging) systems, as described in US Pat.

JP 2010-185769 A

In the LiDAR system as described above, usually, infrared light with a wavelength of 905 nm is emitted, and the distance is calculated from the time it takes for the infrared light reflected by the traveling vehicle, which is the object, to return. ing. Therefore, when the reflection characteristics of the infrared light on the target object are poor, the above calculation becomes difficult. A possible solution to the above problem is to attach a member having excellent retroreflectivity to infrared light to the vehicle.
However, when the member is attached to the vehicle, it is necessary from the viewpoint of design that the color of the vehicle itself is not spoiled. Moreover, when the member is attached to the window of the vehicle, it must be transparent.
Moreover, when it is applied to a vehicle, it is also required to have excellent scratch resistance.
In other words, if a member having excellent scratch resistance, excellent retroreflection of infrared light, and low haze can be developed, the above problems can be solved.

SUMMARY OF THE INVENTION An object of the present invention is to provide a laminate having excellent scratch resistance, excellent retroreflectivity of infrared light, and low haze in view of the above circumstances.

The inventors have found that the above problems can be solved by the following configuration.

(1) a protective layer;
a substrate having an uneven structure on the surface opposite to the protective layer;
a reflective layer disposed on a surface having an uneven structure of a substrate and having a surface shape with an uneven structure that follows the uneven structure;
a refractive index adjusting layer disposed on the reflective layer and filling the concave-convex structure of the reflective layer;
and an adhesive layer in this order,
a difference in refractive index at a wavelength of 550 nm between the substrate and the refractive index adjusting layer is 0.20 or less;
When measuring the ratio of reflectance to transmittance at each wavelength in the wavelength range of 500 to 600 nm, the maximum ratio is 0.20 or less,
A laminate having a maximum value of 0.40 or more when measuring the ratio of reflectance to transmittance at each wavelength in a wavelength range of 850 to 950 nm.
(2) When the elastic modulus of the protective layer is E1, the elastic modulus of the substrate is E2, the elastic modulus of the refractive index adjusting layer is E3, and the elastic modulus of the adhesive layer is E4, the following formula (1) and formula The laminate according to (1), which satisfies the relationship (2).
Formula (1) E1>E2>E4
Formula (2) E1>E3>E4
(3) The laminate according to (1) or (2), wherein the reflective layer is a layer selected from the group consisting of a cholesteric liquid crystal layer and a layer containing tabular silver particles.
(4) The laminate according to any one of (1) to (3), wherein the concavo-convex structure has a corner cube shape, a pyramid shape, or a hemispherical shape.
(5) The laminate according to any one of (1) to (4), wherein the uneven structure has a depth of 1 μm or more.
(6) The maximum value of the retroreflectance at each wavelength when light with a wavelength of 850 to 950 nm is incident from a direction inclined 45° from the normal direction of the laminate is 10% or more. The laminate according to any one of (5).

According to the present invention, it is possible to provide a laminate having excellent scratch resistance, excellent retroreflectivity of infrared light, and low haze.

1 is a cross-sectional view of one embodiment of a laminate of the present invention; FIG. FIG. 2 is a top view of a substrate having a hemispherical uneven structure on one surface; FIG. 3 is a cross-sectional view taken along line AA in FIG. 2; FIG. 2 is a top view of a substrate having a prism-shaped uneven structure on one surface; FIG. 5 is a cross-sectional view taken along line BB in FIG. 4; FIG. 2 is a top view of a substrate having a corner cube-shaped uneven structure on one surface. FIG. 7 is a cross-sectional view taken along line CC in FIG. 6; FIG. 4 is a top view of a substrate having a pyramid-shaped uneven structure on one surface; FIG. 9 is a cross-sectional view taken along line DD in FIG. 8; FIG. 3 is a diagram for explaining an angle (θ) formed between the main plane of the flat metal particle and the surface of the uneven structure.

The content of the present disclosure will be described in detail below. The description of the constituent elements described below may be made based on representative embodiments of the present disclosure, but the present disclosure is not limited to such embodiments.
In this specification, the term "to" indicating a numerical range is used to include the numerical values before and after it as lower and upper limits.
In the numerical ranges described stepwise in this specification, the upper limit or lower limit described in one numerical range may be replaced with the upper limit or lower limit of the numerical range described in other steps. good. Moreover, in the numerical ranges described in this specification, the upper and lower limits of the numerical ranges may be replaced with the values shown in the examples.
Furthermore, the amount of each component in the composition herein refers to the sum of the corresponding substances present in the composition when there are multiple substances corresponding to each component in the composition, unless otherwise specified. means quantity.
As used herein, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.
As used herein, "total solid content" refers to the total mass of components excluding the solvent from the total composition of the composition. Moreover, as described above, the “solid content” is the component excluding the solvent, and may be solid or liquid at 25° C., for example.
In the description of a group (atomic group) in the present specification, a description that does not describe substitution or unsubstituted includes not only those having no substituents but also those having substituents. For example, the term “alkyl group” includes not only alkyl groups having no substituents (unsubstituted alkyl groups) but also alkyl groups having substituents (substituted alkyl groups).
In this specification, (meth)acryl is a generic term including acryl and methacryl, and (meth)acryloxy is a generic term including acryloxy and methacryloxy.
Furthermore, in the present disclosure, a combination of two or more preferred aspects is a more preferred aspect.
In addition, unless otherwise specified, the weight average molecular weight (Mw) and number average molecular weight (Mn) in the present disclosure use columns of TSKgel GMHxL, TSKgel G4000HxL, and TSKgel G2000HxL (all trade names manufactured by Tosoh Corporation). It is a molecular weight converted using polystyrene as a standard substance, detected with a solvent THF (tetrahydrofuran) and a differential refractometer using a gel permeation chromatography (GPC) analyzer.
The present disclosure will now be described in detail.

FIG. 1 shows a cross-sectional view of an embodiment of the laminate of the present invention (hereinafter also simply referred to as "laminate").
The laminate 10 has a protective layer 12, a base material 14, a reflective layer 16, a refractive index adjusting layer 18, and an adhesive layer 20 in this order.
The substrate 14 has an uneven structure on the surface 14a opposite to the protective layer 12 side. The uneven structure shown in FIG. 1 corresponds to a pyramid shape. As will be described later, the concave-convex structure may have a shape other than a pyramid shape.
The reflective layer 16 is disposed on the surface 14a of the substrate 14 having the uneven structure, and has a surface shape of the uneven structure following the uneven structure. That is, the reflective layer 16 is a layer having a predetermined thickness formed along the uneven structure of the base material 14 . An uneven structure similar to the uneven structure formed on the surface of the substrate 14 is formed on one surface of the reflective layer 16 .
The refractive index adjustment layer 18 is a layer arranged on the reflective layer 16 so as to fill the uneven structure of the reflective layer 16 . In other words, it is preferable that the surface of the refractive index adjustment layer 18 opposite to the reflective layer 16 is a flat surface.

In the laminate of the present invention, the difference in refractive index at a wavelength of 550 nm between the substrate and the refractive index adjusting layer is 0.20 or less. Above all, the difference in refractive index is preferably 0.10 or less, and more preferably 0.01 or less, because the haze of the laminate is lower. Although the lower limit is not particularly limited, 0 can be mentioned.
The method for measuring the refractive index is as follows.
As a method for measuring the refractive index of the refractive index adjustment layer, a refractive index adjustment layer having a thickness in the range of 200 to 800 nm is formed on a Si substrate, and an ellipsometer (manufactured by JASCO Corporation, M150) is used to measure the refractive index adjustment layer at a wavelength of 550 nm. and a method of measuring the refractive index of
As a method for measuring the refractive index of a base material, a solution obtained by dissolving the base material in a solvent is spin-coated on a Si substrate to form a refractive index measurement film having a thickness in the range of 200 to 800 nm, A method of measuring the refractive index at a wavelength of 550 nm of the refractive index measurement film (substrate) with an ellipsometer (manufactured by JASCO Corporation, M150) can be mentioned.

In the laminate of the present invention, the ratio of the reflectance to the transmittance at each wavelength in the wavelength range of 500 to 600 nm (reflectance/transmittance) (hereinafter also simply referred to as "first ratio") is measured. is 0.20 or less. Above all, the first ratio is preferably 0.15 or less, and more preferably 0.12 or less, from the viewpoint that the visible light transmittance of the laminate is more excellent. Although the lower limit of the first ratio is not particularly limited, 0 is an example.
In the laminate of the present invention, when measuring the ratio of reflectance to transmittance at each wavelength (reflectance/transmittance) (hereinafter simply referred to as "second ratio") in the wavelength range of 850 to 950 nm is 0.40 or more. Above all, the second ratio is preferably 0.60 or more, and more preferably 0.80 or more, from the viewpoint that the infrared light reflectivity of the laminate is more excellent. Although the upper limit of the second ratio is not particularly limited, 100 can be mentioned.
The method for measuring the first ratio and the second ratio is to calculate the transmittance and reflectance in a predetermined wavelength range using an ultraviolet visible near infrared spectrophotometer (manufactured by Shimadzu Corporation, UV-3100PC), A method of calculating the above ratio may be mentioned.

When E1 is the elastic modulus of the protective layer, E2 is the elastic modulus of the substrate, E3 is the elastic modulus of the refractive index adjusting layer, and E4 is the elastic modulus of the adhesive layer, the formula (1 ) and formula (2).
Formula (1) E1>E2>E4
Formula (2) E1>E3>E4

The elastic modulus E1 of the protective layer is preferably from 1 to 25 GPa, more preferably from 3 to 15 GPa, from the standpoint of better scratch resistance of the laminate.
The elastic modulus E2 of the base material is preferably 0.1 to 10 GPa, more preferably 0.3 to 5 GPa, and even more preferably 0.5 to 3 GPa, from the standpoint of better scratch resistance of the laminate.
The elastic modulus E3 of the refractive index adjusting layer is preferably from 0.1 to 5 GPa, more preferably from 0.3 to 1 GPa, from the standpoint of better scratch resistance of the laminate.
The elastic modulus E4 of the adhesive layer is preferably from 0.0001 GPa to 0.1 GPa, more preferably from 0.0002 GPa to 0.01 GPa, from the standpoint of better scratch resistance of the laminate.

The modulus of elasticity of each layer is measured using a dynamic ultra-micro hardness tester (DUH-201S, manufactured by Shimadzu Corporation).
The measurement conditions are as follows.
・Type of indenter: Vickers
・Test mode: load-unload test ・Test force: 40 mN
・Load speed: 1.3239mN/sec
・Holding time: 5 sec
Each layer may be measured in a cut cross section of the laminate, or may be measured by exposing the layer to be measured by cutting or the like. may be measured at

In addition, the maximum value of the retroreflectance at each wavelength when light with a wavelength of 850 to 950 nm is incident from a direction inclined 45° from the normal direction of the laminate is not particularly limited, but is 10% or more. is preferred. Although the upper limit is not particularly limited, it is often 50% or less.
The method for measuring the retroreflectance is as follows.
When light with a wavelength of 850 to 950 nm is incident from a direction inclined by 45° from the normal direction of the surface of the laminate, the intensity (Is) of light reflected in the incident direction of the light is measured.
A white diffuser plate made of barium sulfate is used instead of the laminate, and the same measurement as described above is performed to measure the strength (Ii).
The retroreflectance (%) at each wavelength is defined as Is/Ii×100 and calculated. Select the maximum value of retroreflectance at each wavelength.
In the above measurement, the laminate was irradiated with light from a light source (HL-2000-HP-FHSA, manufactured by Ocean Optics) through an optical fiber (VIS/NIR 200 μm Q/BIF, manufactured by Ocean Optics) and reflected at the same angle. The light is guided again through the optical fiber to a detector (Photonic Multi-Channel Analyzer C7473-36, manufactured by Hamamatsu Photonics Co., Ltd.), and the amount of light is measured.

Each member constituting the laminate will be described in detail below.

<Protective layer>
The laminate has a protective layer.
The protective layer may be a layer having sufficient strength to protect the reflective layer and the like, but is preferably a layer containing a resin having excellent durability against light, heat, humidity, and the like.
The protective layer is preferably a layer obtained by curing a layer containing the material described below, and more preferably a layer obtained by curing the layer containing the material described below after molding.

From the viewpoint of durability, the protective layer preferably contains a resin.
The resin is preferably at least one selected from the group consisting of siloxane resins, fluororesins, urethane resins, (meth)acrylic resins, polyester resins, melamine resins, and olefin resins. At least one selected from the group consisting of urethane resins is more preferred.
The fluororesin is not particularly limited, but includes those described in paragraphs 0076 to 0106 of JP-A-2009-217258 and paragraphs 0083-0127 of JP-A-2007-229999.
Examples of fluororesins include fluoroalkyl resins obtained by substituting fluorine for hydrogen in olefins, such as polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, perfluoroalkoxyalkane, and perfluoroethylene propene. , and ethylene tetrafluoroethylene. In addition to the above, examples of the fluororesin include a water-dispersible fluororesin copolymerized with an emulsifier or a component that enhances affinity with water. Specific examples of the fluororesin include Lumiflon and Obbligato manufactured by Asahi Glass Co., Ltd., Zeffle and Neoflon manufactured by Daikin Industries, Ltd., Teflon (registered trademark) manufactured by DuPont, and Kynar manufactured by Arkema.

The protective layer preferably contains a siloxane compound or a hydrolytic condensate thereof.
In particular, as the siloxane compound, at least one compound selected from the group consisting of a siloxane compound represented by the following formula 1 and a hydrolytic condensate of the siloxane compound represented by the following formula 1 (hereinafter referred to as a specific siloxane Also referred to as a compound.) is preferred.

In Formula 1, R ¹ , R ² and R ³ each independently represent an alkyl group having 1 to 6 carbon atoms or an alkenyl group, and R ⁴ each independently represent an alkyl group, vinyl group, epoxy group, vinyl selected from the group consisting of phenyl group, (meth)acryloxy group, (meth)acrylamide group, amino group, isocyanurate group, ureido group, mercapto group, sulfide group, polyoxyalkyl group, carboxy group and quaternary ammonium group; represents an alkyl group having a group, m represents an integer of 0 to 2, and n represents an integer of 1 to 20.

The hydrolytic condensate of the siloxane compound represented by Formula 1 is obtained by hydrolyzing at least a part of the siloxane compound represented by Formula 1 and the substituents on the silicon atoms in the siloxane compound represented by Formula 1. , and a compound having a silanol group are condensed.

The alkyl group or alkenyl group having 1 to 6 carbon atoms in R ¹ , R ² and R ³ in Formula 1 may be linear, branched, or have a ring structure. good too. R ¹ , R ² and R ³ are preferably alkyl groups having 1 to 6 carbon atoms from the viewpoint of the strength, light transmittance and haze of the protective layer.
Examples of alkyl groups having 1 to 6 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, tert-butyl group, n-pentyl group, n-hexyl group and cyclohexyl group. , a methyl group or an ethyl group is preferred, and a methyl group is more preferred.
R ⁴ in Formula 1 is preferably an alkyl group, more preferably an alkyl group having 1 to 8 carbon atoms, from the viewpoints of strength, light transmittance and haze of the protective layer.
The number of carbon atoms in R ⁴ in Formula 1 is preferably 1-40, more preferably 1-20, and even more preferably 1-8.
m in Formula 1 is preferably 1 or 2, more preferably 2, from the viewpoint of the strength, light transmittance and haze of the protective layer.
n in Formula 1 is preferably an integer of 2 to 20 from the viewpoint of the strength, light transmittance and haze of the protective layer.

Specific siloxane compounds include Shin-Etsu Chemical Co., Ltd. KBE-04, KBE-13, KBE-22, KBE-1003, KBM-303, KBE-403, KBM-1403, KBE-503, KBM-5103, KBE-903, KBE-9103P, KBE-585, KBE-803, KBE-846, KR-500, KR-515, KR-516, KR-517, KR-518, X-12-1135, X-12- Dynasylan 4150 manufactured by Evonik Japan Co., Ltd.; MKC silicates MS51, MS56, MS57, MS56S manufactured by Mitsubishi Chemical Corporation; Ethyl silicate 28, N-propyl silicate, N manufactured by Colcoat Co., Ltd. -butyl silicate, SS-101;

A urethane resin can be obtained by a reaction of a diisocyanate compound and a polyol, or a polymerization reaction of a urethane acrylate compound.

Polyols used in the synthesis of the urethane resin include polyester polyols, polyether polyols, polycarbonate polyols, and polyacrylic polyols. Among them, polyester polyol or polyacrylic polyol is preferable from the viewpoint of impact resistance.

A polyester polyol can be obtained by a known method using an esterification reaction using a polybasic acid and a polyhydric alcohol.

A polycarboxylic acid is used as the polybasic acid component of the polyester polyol, and if necessary, a monobasic fatty acid or the like may also be used together. Polycarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, tetrahydroisophthalic acid, hexahydrophthalic acid, hexahydroterephthalic acid, trimellitic acid, pyromellitic acid, and other such aromatic Polycarboxylic acids, adipic acid, sebacic acid, succinic acid, azelaic acid, fumaric acid, maleic acid, itaconic acid, and other such aliphatic polycarboxylic acids and their anhydrides.
These polybasic acids may be used alone, or it is possible to use a combination of two or more thereof.

The polyhydric alcohol component of the polyester polyol and similarly the polyhydric alcohol used in the synthesis of the urethane resin include glycols and trihydric or higher polyhydric alcohols.
Glycols include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, neopentyl glycol, hexylene glycol, 1,3-butanediol and 1,4-butane. diols, 1,5-pentanediol, 1,6-hexanediol, 2-butyl-2-ethyl-1,3-propanediol, methylpropanediol, cyclohexanedimethanol, and 3,3-diethyl-1,5 - Pentanediol.
Trihydric or higher polyhydric alcohols include glycerol, trimethylolethane, trimethylolpropane, pentaerythritol, and dipentaerythritol.
These polyhydric alcohols can be used alone, or two or more of them can be used in combination.

Dimethylol alkanoates include dimethylol propionate, dimethylol butanoate, dimethylol pentanoate, dimethylol heptanoate, dimethylol octanoate, and dimethylol nonanoate.
These dimethylol alkanoates can be used alone, or two or more of them can be used in combination.

Polyacrylic polyols include various known polyacrylic polyols having hydroxyl groups capable of reacting with isocyanate groups.

Polyisocyanate compounds include 4,4′-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 1,5-naphthalene diisocyanate, p- or m-phenylene diisocyanate, xylylene diisocyanate, and m- Aromatic diisocyanates such as tetramethylxylylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, 1,4-cyclohexylmethane diisocyanate, and alicyclic diisocyanates such as hydrogenated tolylene diisocyanate, and hexa Aliphatic diisocyanates such as methylene diisocyanate are included.
These diisocyanate compounds may be used alone, or it is possible to use combinations of two or more thereof.

The urethane (meth)acrylate will be described. Examples of the method for producing the urethane (meth)acrylate include a method of subjecting a compound having a hydroxy group and a (meth)acryloyl group to a polyisocyanate compound for a urethanization reaction.

Examples of compounds having a hydroxy group and a (meth)acryloyl group include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxy-n-butyl (meth)acrylate, 2-hydroxypropyl ( meth) acrylate, 2-hydroxy-n-butyl (meth) acrylate, 3-hydroxy-n-butyl (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, N-(2-hydroxyethyl) ( meth)acrylamide, glycerin mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, 2-hydroxy-3-phenoxypropyl(meth)acrylate, 2-(meth)acryloyloxyethyl-2 -Hydroxyethyl phthalate, and monofunctional (meth)acrylates having a hydroxy group such as lactone-modified (meth)acrylates having a hydroxy group at the end; trimethylolpropane di(meth)acrylate, isocyanurate ethylene oxide (EO)-modified di Polyfunctional (meth)acrylates having a hydroxy group such as acrylates, pentaerythritol tri(meth)acrylates, and dipentaerythritol penta(meth)acrylates can be mentioned. Among them, pentaerythritol triacrylate or dipentaerythritol pentaacrylate is preferable from the viewpoint of improving the scratch resistance of the protective layer.
These hydroxy group- and (meth)acryloyl group-containing compounds may be used alone, or two or more of them may be used in combination.

Examples of the polyisocyanate compounds include aromatic diisocyanate compounds such as tolylene diisocyanate, diphenylmethane diisocyanate, m-xylylene diisocyanate, and m-phenylenebis(dimethylmethylene) diisocyanate; hexamethylene diisocyanate, lysine diisocyanate, 1,3-bis Aliphatic compounds such as (isocyanatomethyl)cyclohexane, 2-methyl-1,3-diisocyanatocyclohexane, 2-methyl-1,5-diisocyanatocyclohexane, 4,4′-dicyclohexylmethane diisocyanate, and isophorone diisocyanate Or an alicyclic diisocyanate compound is mentioned.

The urethane (meth)acrylate can be cured by irradiation with actinic rays. The actinic rays refer to ionizing radiation such as ultraviolet rays, electron beams, α rays, β rays, and γ rays. When the protective layer is cured by irradiating ultraviolet rays as actinic rays after molding, it is preferable to add a photopolymerization initiator to the protective layer to improve curability. Moreover, if necessary, a photosensitizer can be further added to improve curability.

The protective layer may contain an ultraviolet absorber.
A UV absorber is a compound having a molecular weight of less than 5,000 that has UV absorption capability. The above molecular weight refers to the weight-average molecular weight measured by the method described above when the ultraviolet absorber has a molecular weight distribution. In the absence of a molecular weight distribution, molecular weights are determined using, for example, electrospray ionization mass spectroscopy (ESI-MS).
As the ultraviolet absorber, a compound having a maximum absorption wavelength of 380 nm or less is preferable, and a compound having a maximum absorption wavelength of 250 to 380 nm (preferably 270 to 380 nm) is more preferable.
Ultraviolet absorbers include triazine compounds, benzotriazole compounds, benzophenone compounds, salicylic acid compounds, and metal oxide particles.
From the viewpoint of ultraviolet absorption performance, the ultraviolet absorber preferably contains a triazine compound or a benzotriazole compound, and more preferably contains a triazine compound.
The total content of the triazine compound and benzotriazole compound in the ultraviolet absorber is preferably 80% by mass or more with respect to the total amount of the ultraviolet absorber.

The protective layer may contain a surfactant.
Surfactants include nonionic surfactants, anionic surfactants that are ionic surfactants, cationic surfactants, and amphoteric surfactants.
Among them, at least one surfactant selected from the group consisting of nonionic surfactants and cationic surfactants is preferred, and cationic surfactants are more preferred.

The protective layer may contain other components in addition to the components described above, depending on the purpose.
Known additives can be used as other components, and examples thereof include antistatic agents, condensation catalysts for siloxane compounds, and preservatives.

The protective layer may contain an antistatic agent.
The antistatic agent is used for the purpose of imparting antistatic properties to the protective layer and suppressing adhesion of contaminants.
The antistatic agent for imparting antistatic properties is not particularly limited.
The antistatic agent is preferably at least one selected from the group consisting of metal oxide particles, metal nanoparticles, conductive polymers, and ionic liquids.
Antistatic agents may be used in combination of two or more.

Metal oxide particles are not particularly limited, but include tin oxide particles, antimony-doped tin oxide particles, tin-doped indium oxide particles, zinc oxide particles, and silica particles.
The average primary particle size of the metal oxide particles is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less. Moreover, as a lower limit, 2 nm or more is preferable.
The shape of the particles is not particularly limited, and may be spherical, plate-like, or needle-like.
The average primary particle size of the metal oxide particles can be determined from the photograph obtained by observing the dispersed particles with a transmission electron microscope. From the photographic image, the projected area of the particles is obtained, and the equivalent circle diameter is obtained therefrom and taken as the average particle diameter (average primary particle diameter). The average primary particle size in this specification is a value calculated by measuring the projected area of 300 or more particles and determining the equivalent circle diameter.
When the shape of the metal oxide particles is not spherical, other methods such as dynamic light scattering may be used.

The antistatic agents may be used alone or it is possible to use a combination of two or more thereof.
The content of the antistatic agent in the protective layer is not particularly limited, but is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, relative to the total mass of the protective layer.
The content of the antistatic agent when metal oxide particles are used as the antistatic agent is preferably 30% by mass or less, more preferably 20% by mass or less, and 10% by mass or less, relative to the total mass of the protective layer. More preferred.

The protective layer may contain a condensation catalyst that promotes condensation of the siloxane compound.
By containing a condensation catalyst in the protective layer, it is possible to form a protective layer with more excellent durability.

(Method for forming protective layer)
The method of forming the protective layer is not particularly limited, but a method of applying a protective layer-forming coating liquid containing predetermined components and drying to form the protective layer is preferred.

The coating liquid for forming a protective layer may contain the above-described various components (eg, siloxane compound, surfactant).
Moreover, the protective layer-forming coating liquid may contain a solvent (eg, water and an organic solvent).
A method for preparing the protective layer-forming coating liquid is not particularly limited, and a known method can be used. For example, there is a method of mixing the above-described various components (eg, siloxane compound, surfactant, and solvent) and the like.

The method of applying the protective layer-forming coating liquid is not particularly limited, and includes spray coating, brush coating, roller coating, bar coating, and dip coating.
In addition, before applying the coating liquid for forming a protective layer, the object to be coated with the coating liquid for forming a protective layer is subjected to corona discharge treatment, glow treatment, atmospheric pressure plasma treatment, flame treatment, and ultraviolet irradiation treatment. You may give surface treatments, such as.

Drying of the protective layer-forming coating solution may be performed at room temperature (25° C.) or by heating. The heating temperature is preferably 40 to 200°C, more preferably 40 to 120°C.
Moreover, the heating time is preferably 1 to 30 minutes.

When the protective layer-forming coating liquid contains a curable component, a coating film formed from the protective layer-forming coating liquid may be subjected to curing treatment (for example, light irradiation treatment and heat treatment).
As a light source for the light irradiation treatment, any light source capable of irradiating light in a wavelength range (for example, 365 nm and 405 nm) capable of curing the protective layer can be appropriately selected and used.
Specifically, ultrahigh-pressure mercury lamps, high-pressure mercury lamps, metal halide lamps, and the like are included.
The exposure amount is not particularly limited, and is preferably 5 to 2,000 mJ/cm ² , more preferably 10 to 1,000 mJ/cm ² .

As the protective layer-forming coating liquid, a protective layer-forming coating liquid containing hollow particles is preferably used.
Here, as the hollow particles, hollow silica particles containing silica as a main component are preferable from the viewpoint of affinity with the siloxane resin forming the matrix.
Examples of hollow silica particles include hollow particles described in JP-A-2013-237593 and WO 2007/060884.
The hollow silica particles may be surface-unmodified hollow silica particles or surface-modified hollow silica particles.
In addition, the hollow particles are subjected to physical surface treatment such as plasma discharge treatment and corona discharge treatment in order to stabilize the dispersion in the coating solution for forming the protective layer, or to increase the affinity and bonding with the siloxane resin. Treatment and chemical surface treatment with a surfactant, a coupling agent, or the like may be performed.

The porosity of the protective layer is preferably 10 to 80%, more preferably 15 to 75%, even more preferably 20 to 55%, from the viewpoint of light transmission and scratch resistance.
The diameter of the voids in the protective layer (hereinafter also referred to as "void diameter") is preferably 25 nm or more, more preferably 30 nm or more, from the viewpoints of strength, light transmittance, and haze. The upper limit of the void diameter is preferably 80 nm or less, more preferably 70 nm or less, from the viewpoint of scratch resistance.

The method for measuring the pore diameter, the porosity, and the variation coefficient of the pore diameter of the protective layer is as follows.
The laminate including the protective layer is cut in a direction orthogonal to the surface, and the cut surface is observed with a scanning electron microscope (SEM) to measure the void diameter and void ratio.
Equivalent circle diameters are calculated for each of 200 arbitrarily selected voids in the SEM image of the cut surface (magnification: 50,000), and the average value is defined as the void diameter.
In addition, the porosity was obtained by image processing the void portion and the matrix portion (i.e., the portion other than the void containing the resin) on the SEM image (magnification of 50,000) of the cut surface using image processing software (ImageJ). (binarization) and separation, and the ratio of the void portion is calculated as the porosity.
When the diameter of the voids is not anisotropic, the void ratio is obtained as the volume fraction of the voids in the resin.

The refractive index of the protective layer is preferably 1.05 to 1.6, more preferably 1.2 to 1.5, even more preferably 1.2 to 1.4, from the viewpoint of visibility and antireflection properties. .
The refractive index is the refractive index for light with a wavelength of 550 nm at 25°C.
In addition, when used for the exterior of automobiles, etc., the refractive index should be set in a range close to those refractive indices, that is, in the range of 1.4 to 1.5, in order to make contamination such as wax and gasoline inconspicuous. , dirt becomes less conspicuous, which is preferable.
In addition, the refractive index of the protective layer is obtained by measuring the transmission spectrum with a spectrophotometer for a single film of the protective layer formed on the non-alkali glass OA-10G. The thickness and refractive index of each layer are obtained by performing fitting analysis using the transmittance calculated by the method. It can also be measured using a Carnew precision refractometer (KPR-3000, manufactured by Shimadzu Corporation).

Although the thickness of the protective layer is not particularly limited, it is preferably 1 to 25 μm, more preferably 2 to 20 μm, even more preferably 3 to 15 μm. When the thickness of the protective layer is 1 μm or more, sufficient hardness can be obtained, and the effect of dispersing the impact in the in-plane direction can be obtained. It can be used and has excellent scratch resistance.

<Base material>
A laminate has a substrate.
The substrate is not particularly limited, and known substrates can be used. As the base material, a resin base material is preferable.
When the substrate is a resin substrate, the resin contained in the substrate includes polyethylene terephthalate (PET) resin, polyethylene naphthalate (PEN) resin, (meth)acrylic resin, urethane resin, urethane-(meth)acrylic resin, Polycarbonate (PC) resins, acrylic-polycarbonate resins, triacetylcellulose (TAC), cycloolefin polymers (COP), and acrylonitrile/butadiene/styrene copolymer resins (ABS resins).
Among them, the base material is preferably a (meth)acrylic resin base material, a polycarbonate base material, or a polypropylene base material from the viewpoint of moldability and strength, and a (meth)acrylic resin base material or a polycarbonate base material. wood is more preferred.

The base material may contain additives, if necessary.
Additives include mineral oil, hydrocarbons, fatty acids, alcohols, fatty acid esters, fatty acid amides, metallic soaps, natural waxes, lubricants such as silicone, inorganic flame retardants such as magnesium hydroxide and aluminum hydroxide, halogen-based And organic flame retardants such as phosphorus, metal powder, talc, calcium carbonate, potassium titanate, glass fiber, carbon fiber, and organic or inorganic fillers such as wood flour, antioxidants, UV inhibitors, lubricants , dispersants, coupling agents, blowing agents, and additives such as coloring agents, and polyolefin resins, polyester resins, polyacetal resins, polyamide resins, and polyphenylene ether resins, etc., engineering other than the above resins plastics.

A commercially available product may be used as the base material.
Commercially available products include the Technoloy (registered trademark) series (acrylic resin film or acrylic resin/polycarbonate resin laminated film, manufactured by Sumitomo Chemical Co., Ltd.), ABS film (manufactured by Okamoto Co., Ltd.), ABS sheet (manufactured by Sekisui Seisei Co., Ltd.) ), Teflex (registered trademark) series (PET film, manufactured by Teijin Film Solution Co., Ltd.), Lumirror (registered trademark) easy-molding type (PET film, manufactured by Toray Industries, Inc.), and Pure Thermo (polypropylene film, manufactured by Idemitsu Unitech Co., Ltd.).

The substrate has an uneven structure on the surface opposite to the protective layer side.
The uneven structure may include only a plurality of protrusions, may include only a plurality of recesses, or may include a plurality of protrusions and recesses. A structure in which hemispherical protrusions are formed is an example of the uneven structure including only a plurality of protrusions. A prism shape, a pyramid shape, and a corner cube shape can be given as examples of the concave-convex structure including a plurality of convex portions and concave portions.
As the uneven structure, a prism shape, a pyramid shape, a hemispherical shape, or a corner cube shape is preferable.
The uneven structure preferably includes a plurality of protrusions and recesses, more preferably a prism shape, a pyramid shape, or a corner cube shape, and even more preferably a corner cube shape.
In this specification, the corner cube shape refers to a shape obtained by combining three planes perpendicular to each other. Deformed shapes are also included.

It is preferable that at least one of the convex portions and the concave portions has a periodic pitch as the concave-convex structure.
The width of a convex or concave portion refers to the distance between the lowest points when cut by a plane that is perpendicular to the surface direction and passes through the highest and lowest points of the convex portion in the case of a concave portion. The distance between the highest points when cut by a plane that is perpendicular to and passes through the highest and lowest points of the recess, and if the sizes of individual pitches are different, the average of the distances between the lowest points or the highest points value. The pitch refers to the distance between the highest points in the case of convex portions, and the distance between the lowest points in the case of concave portions.

2 and 3 are schematic diagrams of an aspect in which the uneven structure on the surface of the substrate has hemispherical protrusions, FIG. 2 is a top view, and FIG. 3 is a line AA in FIG. It is a sectional view.
When the uneven structure is the hemispherical shape shown in FIGS. 2 and 3, the pitch is the distance P between the vertices of the two nearest hemispherical protrusions, and the width of the hemispherical protrusion is the hemispherical portion. Corresponds to the diameter R. Further, when the concave-convex structure has a hemispherical shape, the pitch may not match the width of the convex portion.

4 and 5 are schematic diagrams of an embodiment in which the concave-convex structure on the surface of the substrate has a prism shape, FIG. 4 is a top view, and FIG. 5 is a cross-sectional view taken along line BB in FIG. be.
When the uneven structure is the prism shape shown in FIGS. 4 and 5, the pitch corresponds to P in FIG. 5 and the width of the convex portion corresponds to R in FIG. When the uneven structure is prism-shaped, it is preferable that the pitch and the width of the protrusions match.

6 and 7 are schematic diagrams of an aspect in which the concave-convex structure on the surface of the substrate is in the shape of a corner cube, FIG. 6 being a top view, and FIG. 7 being a cross-sectional view taken along line CC in FIG. is.
When the uneven structure is the corner cube shape shown in FIGS. 6 and 7, the pitch corresponds to P in FIG. It corresponds to R in FIG.

8 and 9 are schematic diagrams of an aspect in which the concave-convex structure on the surface of the substrate has a pyramid shape, FIG. 8 is a top view, and FIG. 9 is a cross-sectional view taken along line DD in FIG. be.
When the uneven structure is the pyramid shape shown in FIGS. 8 and 9, the pitch corresponds to P in FIG. corresponds to the R of

The depth (or height) of the uneven structure is preferably 1 μm or more, more preferably 1 to 200 μm, even more preferably 1 to 100 μm, and particularly preferably 3 to 80 μm, from the viewpoint of reflectivity and retroreflectivity.
The width of the concave-convex structure is preferably 1 to 100 μm, more preferably 3 to 80 μm, from the viewpoint of reflectivity and retroreflectivity.
Further, the ratio of depth to width in the concave-convex structure is preferably width/depth=100/1 to 1/2, more preferably 50/1 to 1/1.

The method of forming the uneven structure is not particularly limited, but examples include a method of preparing a mold in which a shape corresponding to the uneven structure is formed in advance, and transferring the uneven structure to a base material having no uneven structure.
In order to make the reflective layer, which will be described later, follow the uneven structure on the surface of the substrate, a laminate having a substrate and a reflective layer disposed on the substrate is prepared, and the uneven structure is provided on the reflective layer side of the laminate. may be transcribed.
Examples of the transfer method include a method in which the mold is directly pressed against the substrate, a method in which pressure is applied using a vacuum laminator, and the like.

The thickness of the substrate is not particularly limited, but is preferably 1 µm or more, more preferably 10 µm or more, still more preferably 20 µm or more, and particularly preferably 50 µm or more. The upper limit is preferably 500 µm or less, more preferably 450 µm or less, and particularly preferably 200 µm or less.

<Reflective layer>
The laminate has a reflective layer. The reflective layer is disposed on the surface of the substrate having the uneven structure, and has a surface shape of the uneven structure that follows the uneven structure.

Examples of the reflective layer include a cholesteric liquid crystal layer, a layer containing flat metal particles, an optical multilayer film (dielectric multilayer film), and a layer containing a chromic material.
Among them, a cholesteric liquid crystal layer or a layer containing flat metal particles is preferable, and a cholesteric liquid crystal layer is more preferable.

(cholesteric liquid crystal layer)
The reflective layer is preferably a cholesteric liquid crystal layer in terms of retroreflectivity and designability.

In the cholesteric liquid crystal layer, by changing at least one selected from the group consisting of the pitch of the helical structure, the refractive index, and the thickness, it is possible to adjust the color change depending on the viewing angle and the viewing color itself. The pitch of the helical structure can be easily adjusted by changing the amount of chiral agent added. Adjustment of the pitch of the helical structure is described in Fuji Film Research Report No. 50 (2005) p. 60-63, which description is incorporated herein. The pitch of the helical structure can also be adjusted by changing conditions such as temperature, illuminance and irradiation time when fixing the cholesteric alignment state.

The cholesteric liquid crystal layer is preferably composed of a liquid crystal compound fixed in a cholesteric alignment state. That is, the cholesteric liquid crystal layer is preferably a layer that fixes the cholesteric liquid crystal phase. The cholesteric alignment state of the liquid crystal compound may be an alignment state that reflects right-handed circularly polarized light or an alignment state that reflects left-handed circularly polarized light. Liquid crystal compounds are not particularly limited, and various known compounds can be used.

The cholesteric liquid crystal layer is preferably a layer obtained by curing a liquid crystal composition.
The liquid crystal composition for forming the cholesteric liquid crystal layer may contain, for example, a liquid crystal compound, a chiral agent, an alignment control agent, a polymerization initiator and an alignment aid.
Components that may be contained in the liquid crystal composition are described in detail below.

-Liquid Crystal Compound-
The liquid crystal compound includes a rod-like type and a disk-like type depending on its shape. Furthermore, low-molecular-weight and high-molecular-weight types are mentioned, respectively. In the present disclosure, the term "polymer" in liquid crystal compounds refers to those having a degree of polymerization of 100 or more (Polymer Physics: Phase Transition Dynamics, Masao Doi, p.2, Iwanami Shoten, 1992).
As the liquid crystal compound, a rod-like liquid crystal compound is preferable.
As the liquid crystal compound, two or more rod-like liquid crystal compounds, two or more discotic liquid crystal compounds, or a mixture of a rod-like liquid crystal compound and a discotic liquid crystal compound may be used. It is more preferable to use a rod-like liquid crystal compound or a disk-like liquid crystal compound having a reactive group because it can reduce temperature change and humidity change, and at least one liquid crystal molecule has two or more reactive groups. is more preferred. In the case of a mixture of two or more liquid crystal compounds, at least one preferably has two or more reactive groups.
In this specification, when a layer formed from a composition containing a liquid crystal compound is described, the formed layer may not contain a compound having liquid crystallinity. For example, a layer in which the above low-molecular-weight liquid crystal compound has a group that reacts with heat, light, etc., and as a result, polymerizes or crosslinks due to reaction with heat, light, etc., becomes high molecular weight, and loses liquid crystallinity. may be

Moreover, it is preferable to use a liquid crystal compound having two or more reactive groups with different crosslinking mechanisms. When using the above compound, it is preferable to produce a reflective layer containing a polymer having unreacted reactive groups by selecting conditions and polymerizing only a part of two or more reactive groups.
Cross-linking mechanisms are not particularly limited, but include condensation reactions, hydrogen bonding, and polymerization.
As the crosslinking mechanism, two mechanisms may be used. In this case, at least one of the two or more is preferably polymerization, and it is more preferable to use two or more different polymerizations.
Groups used in the cross-linking reaction include vinyl groups, (meth)acryl groups, epoxy groups, oxetanyl groups, vinyl ether groups, hydroxy groups, carboxy groups, and amino groups.

A compound having two or more reactive groups with different cross-linking mechanisms is a compound that can be cross-linked using stepwise different cross-linking reaction steps. functional groups react as functional groups. Further, for example, in the case of a polymer such as polyvinyl alcohol having a hydroxy group in a side chain, after performing a polymerization reaction to polymerize the polymer, when the hydroxy group in the side chain is crosslinked with an aldehyde or the like, two or more types of Although different crosslinking mechanisms are used, when referring to a compound having two or more different reactive groups in the present disclosure, it means a compound having two or more different reactive groups in the layer at the time the reflective layer is formed. is preferably a compound whose reactive groups can then be crosslinked stepwise.
Further, the reactive group is preferably a polymerizable group. Polymerizable groups include radically polymerizable groups and cationically polymerizable groups.
Among them, liquid crystal compounds having two or more polymerizable groups are preferred.
As reaction conditions for stepwise cross-linking, any of a difference in temperature, a difference in wavelength of light (irradiation), and a difference in polymerization mechanism may be used, but it is preferable to use a difference in polymerization mechanism because the reactions are easily separated. Preferably, it is more preferably controlled by the type of polymerization initiator used.
As a combination of polymerizable groups, a combination of a radically polymerizable group and a cationic polymerizable group is preferred. Among them, a combination in which the radically polymerizable group is a vinyl group or a (meth)acrylic group and the cationic polymerizable group is an epoxy group, an oxetanyl group, or a vinyl ether group is particularly preferable because reactivity can be easily controlled.
Among them, the liquid crystal compound preferably has a radically polymerizable group from the viewpoint of reactivity and ease of fixation of the pitch of the helical structure.
Examples of reactive groups are shown below. Et represents an ethyl group, and n-Pr represents an n-propyl group.

Rod-shaped liquid crystal compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, Phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitriles.
The polymer liquid crystal compound is a polymer compound obtained by polymerizing a rod-like liquid crystal compound having a low-molecular-weight reactive group. Examples of rod-like liquid crystal compounds include those described in JP-A-2008-281989, JP-A-11-513019 (International Publication No. 97/00600), and JP-A-2006-526165.

Specific examples of the rod-like liquid crystal compound are shown below, but are not limited thereto. The compounds shown below can be synthesized by the method described in Japanese Patent Publication No. 11-513019 (International Publication No. 97/00600).

Examples of the discotic liquid crystal compound include low-molecular-weight discotic liquid crystal compounds such as monomers, and polymerizable discotic liquid crystal compounds.
As the discotic liquid crystal compound, C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives, C.I. Destrade et al., Mol. Cryst. 122, 141 (1985); Physicslett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, 70 (1984) and the cyclohexane derivative described in J. Am. M. In the report of Lehn et al., J. Am. Chem. Commun. , 1794 (1985); In the report of Zhang et al., J. Am. Am. Chem. Soc. 116, 2655 (1994), azacrown-based or phenylacetylene-based macrocycles.
The above discotic liquid crystal compound has a structure in which the various structures described above are used as a discotic core at the center of the molecule, and groups (L) such as straight-chain alkyl groups, alkoxy groups, and substituted benzoyloxy groups are radially substituted. , exhibits liquid crystallinity, and includes what is generally called discotic liquid crystal.
However, when such a molecular assembly is uniformly oriented, it exhibits negative uniaxiality, but is not limited to this description. Discotic liquid crystal compounds include those described in paragraphs 0061 to 0075 of JP-A-2008-281989.

Liquid crystal compounds may be used alone, or it is possible to use a combination of two or more thereof.
The content of the liquid crystal compound in the liquid crystal composition is preferably 30 to 99% by mass, more preferably 40 to 99% by mass, more preferably 60 to 99% by mass, based on the total solid content of the liquid crystal composition, from the viewpoint of designability. % is more preferred, and 70 to 98% by mass is particularly preferred.

- Chiral agent (optically active compound) -
The liquid crystal composition preferably contains a chiral agent (optically active compound) from the viewpoints of facilitating formation of a cholesteric liquid crystal layer and facilitating adjustment of the pitch of the helical structure.
A chiral agent has a function of inducing a helical structure in a cholesteric liquid crystal layer.
The chiral agent may be selected depending on the purpose, since the direction of helical twist or helical pitch induced by the liquid crystal compound differs.
The chiral agent is not particularly limited, and known compounds (eg, liquid crystal device handbook, Chapter 3, Section 4-3, chiral agent for TN (twisted nematic), STN (super-twisted nematic), page 199, Nihon Gakkai 142nd Committee of the Promotion Society, 1989), isosorbide, and isomannide derivatives.
A chiral agent generally contains an asymmetric carbon atom, but an axially chiral compound or planar chiral compound that does not contain an asymmetric carbon atom can also be used as the chiral agent.
Examples of axially asymmetric compounds or planar asymmetric compounds preferably include binaphthyl compounds, helicene compounds, or paracyclophane compounds.

The liquid crystal composition preferably contains a chiral agent having a polymerizable group as a chiral agent from the viewpoint of suppressing change in reflectance after molding. More preferably, it contains a chiral agent.
The polymerizable group is not particularly limited as long as it is a polymerizable group, but from the viewpoint of reactivity, an ethylenically unsaturated group or a cyclic ether group is preferred, and an ethylenically unsaturated group is more preferred.
Preferred embodiments of ethylenically unsaturated groups and cyclic ether groups in the chiral agent include vinyl groups, (meth)acryl groups, epoxy groups, oxetanyl groups, and vinyl ether groups.
Furthermore, the chiral agent having a polymerizable group is preferably a chiral agent having two or more polymerizable groups from the viewpoint of reactivity, a chiral agent having two or more ethylenically unsaturated groups, or Chiral agents having two or more cyclic ether groups are more preferred, and chiral agents having two or more ethylenically unsaturated groups are even more preferred.
Also, the chiral agent may be a liquid crystal compound.

As will be described later, when controlling the size of the helical pitch of the cholesteric liquid crystal layer by light irradiation when manufacturing the cholesteric liquid crystal layer, a chiral agent (a chiral agent capable of changing the helical pitch of the cholesteric liquid crystal layer in response to light) Hereinafter, it is also referred to as a “photosensitive chiral agent”.).
A photosensitive chiral agent is a compound that changes its structure by absorbing light and can change the helical pitch of the cholesteric liquid crystal layer. As such a compound, a compound that causes at least one of a photoisomerization reaction, a photodimerization reaction, and a photodecomposition reaction is preferable.
A compound that undergoes a photoisomerization reaction refers to a compound that undergoes stereoisomerization or structural isomerization under the action of light. Photoisomerizable compounds include, for example, azobenzene compounds and spiropyran compounds.
A compound that causes a photodimerization reaction refers to a compound that undergoes an addition reaction between two groups and cyclizes upon irradiation with light. Photodimerization compounds include cinnamic acid derivatives, coumarin derivatives, chalcone derivatives, and benzophenone derivatives.
Moreover, the light is not particularly limited, and includes ultraviolet light, visible light, and infrared light.

As the photosensitive chiral agent, a chiral agent represented by the following formula (CH1) is preferable. The chiral agent represented by the following formula (CH1) can change the orientation structure such as the helical pitch (helical period, twist period) of the cholesteric liquid crystal phase depending on the light intensity at the time of light irradiation.

In formula (CH1), Ar ^CH1 and Ar ^CH2 each independently represent an aryl group or a heteroaromatic ring group, and R ^CH1 and R ^CH2 each independently represent a hydrogen atom or a cyano group.

Ar ^CH1 and Ar ^CH2 in formula (CH1) are each independently preferably an aryl group.
The aryl groups in Ar ^{2 CH1} and Ar ^{2 CH2} of formula (CH1) may have a substituent, and preferably have 6 to 40 total carbon atoms, more preferably 6 to 30 total carbon atoms. Substituents include halogen atoms, alkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, hydroxy groups, acyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, acyloxy groups, carboxy groups, cyano groups, or heterocyclic groups. Halogen atoms, alkyl groups, alkenyl groups, alkoxy groups, hydroxy groups, acyloxy groups, alkoxycarbonyl groups, or aryloxycarbonyl groups are more preferred.
R ^CH1 and R ^CH2 in formula (CH1) are preferably each independently a hydrogen atom.

Among them, Ar ^CH1 and Ar ^CH2 are preferably aryl groups represented by the following formula (CH2) or formula (CH3).

In formula (CH2) and formula (CH3), R ^CH3 and R ^CH4 are each independently a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, an alkoxy group, a hydroxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, a carboxy group, or a cyano group, L ^CH1 and L ^CH2 each independently represent a halogen atom, an alkyl group, an alkoxy group, or a hydroxy group, nCH1 represents an integer of 0 to 4, nCH2 represents an integer of 0 to 6, and * represents a bonding position with an ethylenically unsaturated bond in formula (CH1).

R ^CH3 and R ^CH4 in formula (CH2) and formula (CH3) are each independently a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an aryl group, an alkoxy group, a hydroxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, Alternatively, an acyloxy group is preferred, an alkoxy group, a hydroxy group, or an acyloxy group is more preferred, and an alkoxy group is even more preferred.
L ^CH1 and L ^CH2 in the formulas (CH2) and (CH3) are each independently preferably an alkoxy group having 1 to 10 carbon atoms or a hydroxy group.
nCH1 in the formula (CH2) is preferably 0 or 1.
nCH2 in formula (CH3) is preferably 0 or 1.

The heteroaromatic ring groups in Ar ^{2 CH1} and Ar ^{2 CH2} of formula (CH1) may have a substituent and preferably have 4 to 40 total carbon atoms, more preferably 4 to 30 total carbon atoms. The substituent is preferably a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, a hydroxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, or a cyano group, and a halogen atom. , an alkyl group, an alkenyl group, an aryl group, an alkoxy group, or an acyloxy group are more preferable.
The heteroaromatic ring group is preferably a pyridyl group, a pyrimidinyl group, a furyl group or a benzofuranyl group, more preferably a pyridyl group or a pyrimidinyl group.

Chiral agents may be used alone, or combinations of two or more thereof may be used.
The content of the chiral agent can be appropriately selected according to the structure of the liquid crystal compound to be used and the desired pitch of the helical structure. Therefore, it is preferably 1 to 20% by mass, more preferably 2 to 15% by mass, and still more preferably 3 to 10% by mass, based on the total solid content of the liquid crystal composition.
Further, when a chiral agent having a polymerizable group is used as the chiral agent, the content of the chiral agent having a polymerizable group is preferably 0.2 to 15% by mass based on the total solid content of the liquid crystal composition. 0.5 to 10% by mass is more preferable, 1 to 8% by mass is even more preferable, and 1.5 to 5% by mass is particularly preferable.
Furthermore, when a chiral agent that does not have a polymerizable group is used as the chiral agent, the content of the chiral agent that does not have a polymerizable group is 0.2 to 20% by mass with respect to the total solid content of the liquid crystal composition. It is preferably 0.5 to 15% by mass, and even more preferably 1.5 to 10% by mass.
In addition, the pitch of the helical structure of the cholesteric liquid crystal in the cholesteric liquid crystal layer, and the selective reflection wavelength and its range described later can be easily adjusted not only by the type of liquid crystal compound used but also by adjusting the content of the chiral agent. can be changed. Although it cannot be generalized, if the content of the chiral agent in the liquid crystal composition is doubled, the pitch may be halved and the central value of the selective reflection wavelength may also be halved.

-Polymerization initiator-
The liquid crystal composition preferably contains a polymerization initiator, more preferably a photopolymerization initiator.
Moreover, a radical polymerization initiator and a cationic polymerization initiator are mentioned as a polymerization initiator.

A known polymerization initiator can be used as the polymerization initiator.
Moreover, the polymerization initiator is preferably a photopolymerization initiator capable of initiating a polymerization reaction by irradiation with ultraviolet rays.
Examples of photopolymerization initiators include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether compounds (described in US Pat. No. 2,448,828), α-hydrocarbon-substituted aromatic Acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenylketones (US 3549367), an acridine compound and a phenazine compound (described in JP-A-60-105667, US Pat. No. 4,239,850), and an oxadiazole compound (described in US Pat. No. 4,212,970). mentioned.

Moreover, a well-known thing can be used as a photoradical polymerization initiator.
Photoradical polymerization initiators include α-hydroxyalkylphenone compounds, α-aminoalkylphenone compounds, and acylphosphine oxide compounds.
Further, as the photocationic polymerization initiator, a known one can be used.
Photocationic polymerization initiators include iodonium salt compounds and sulfonium salt compounds.

A polymerization initiator may be used alone, or it is possible to use a combination of two or more thereof.
The content of the polymerization initiator can be appropriately selected according to the structure of the liquid crystal compound to be used and the desired pitch of the helical structure. , and, from the viewpoint of the strength of the cholesteric liquid crystal layer, it is preferably 0.05 to 10% by mass, more preferably 0.05 to 5% by mass, and 0.1 to 2% by mass, based on the total solid content of the liquid crystal composition. % is more preferred, and 0.2 to 1% by mass is particularly preferred.

-Crosslinking agent-
The liquid crystal compound may contain a cross-linking agent in order to improve the strength and durability of the cured cholesteric liquid crystal layer. As the cross-linking agent, one that is cured by ultraviolet rays, heat, humidity, etc. can be preferably used.
The cross-linking agent is not particularly limited and can be appropriately selected depending on the purpose. Examples of cross-linking agents include polyfunctional acrylate compounds such as trimethylolpropane tri(meth)acrylate and pentaerythritol tri(meth)acrylate; epoxy compounds such as glycidyl (meth)acrylate and ethylene glycol diglycidyl ether; aziridine compounds such as 2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate] and 4,4-bis(ethyleneiminocarbonylamino)diphenylmethane; isocyanates such as hexamethylene diisocyanate and biuret type isocyanate compounds; polyoxazoline compounds having oxazoline groups in side chains; and alkoxysilane compounds such as vinyltrimethoxysilane and N-(2-aminoethyl)3-aminopropyltrimethoxysilane.
Also, a known catalyst can be used depending on the reactivity of the cross-linking agent, and productivity can be improved in addition to improving the strength and durability of the cholesteric liquid crystal layer.

A single cross-linking agent may be used, or a combination of two or more thereof may be used.
The content of the cross-linking agent is preferably 1 to 20% by mass, more preferably 3 to 15% by mass, based on the total solid content of the liquid crystal composition, from the viewpoint of the strength and durability of the cholesteric liquid crystal layer.

- Polyfunctional polymerizable compound -
The liquid crystal composition preferably contains a functional polymerizable compound, and more preferably contains a polyfunctional polymerizable compound having the same kind of polymerizable groups.
As the polyfunctional polymerizable compound, a liquid crystal compound having two or more ethylenically unsaturated groups and no cyclic ether group, a liquid crystal compound having two or more cyclic ether groups and having an ethylenically unsaturated group and liquid crystal compounds having two or more ethylenically unsaturated groups and two or more cyclic ether groups, chiral agents having two or more polymerizable groups, and the above crosslinking agents.
Among them, the polyfunctional polymerizable compound includes a liquid crystal compound having two or more ethylenically unsaturated groups and no cyclic ether group, and a liquid crystal compound having two or more cyclic ether groups and an ethylenically unsaturated group. and a chiral agent having two or more polymerizable groups, preferably containing at least one compound selected from the group consisting of a chiral agent having two or more polymerizable groups. is more preferable.

A single polyfunctional polymerizable compound may be used, or a combination of two or more thereof may be used.
The content of the polyfunctional polymerizable compound is preferably 0.5 to 70% by mass, more preferably 1 to 50% by mass, based on the total solid content of the liquid crystal composition, from the viewpoint of suppressing change in reflectance after molding. , more preferably 1.5 to 20% by mass, particularly preferably 2 to 10% by mass.

-Other additives-
The liquid crystal composition may contain additives other than those mentioned above, if necessary.
As other additives, known additives can be used, including surfactants, polymerization inhibitors, antioxidants, horizontal alignment agents, ultraviolet absorbers, light stabilizers, colorants, and metal oxides. particles.

Moreover, the liquid crystal composition may contain a solvent. The solvent is not particularly limited and can be appropriately selected depending on the purpose, but organic solvents are preferred.
The organic solvent is not particularly limited and can be appropriately selected depending on the intended purpose. Hydrogens, esters, and ethers can be mentioned. These may be used alone or it is possible to use a combination of two or more thereof.
Among these, ketones are preferred in consideration of the load on the environment. Moreover, the above-mentioned component may function as a solvent.

The content of the solvent in the liquid crystal composition is not particularly limited, and may be adjusted so that the desired coating properties can be obtained.
The content of solids relative to the total mass of the liquid crystal composition is not particularly limited, but is preferably 1 to 90% by mass, more preferably 5 to 80% by mass, and even more preferably 10 to 80% by mass.

- Application and curing of liquid crystal composition -
The method of applying the liquid crystal composition is not particularly limited, and a roll coating method, a gravure printing method, a spin coating method, a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method. mentioned. A coating film can also be formed by discharging the liquid crystal composition from a nozzle using an inkjet device.

After that, the cholesteric liquid crystal layer is formed by curing the liquid crystal composition. By the curing, the orientation state of the molecules of the liquid crystal compound including the liquid crystal compound is maintained and fixed. Curing is preferably carried out by a polymerization reaction of a polymerizable group such as an ethylenically unsaturated group or a cyclic ether group possessed by a liquid crystal compound, a polymerizable compound, or the like.
When the solvent is used, the coating film is preferably dried by a known method after coating the liquid crystal composition and before the polymerization reaction for curing. For example, it may be dried by standing or may be dried by heating.
In addition, you may heat the obtained coating film as needed, and may orientate a liquid crystal compound.

A cholesteric liquid crystal layer is formed by curing the coating film of the liquid crystal composition formed by the above method. By curing, the orientation state of the molecules of the liquid crystal compound is maintained and fixed.

The curing treatment includes light irradiation treatment and heat treatment.
The light source for exposure can be appropriately selected according to the type of photopolymerization initiator, and is preferably a light source capable of irradiating light in the visible wavelength range (eg, 365 nm and 405 nm). Such light sources include, for example, ultra-high pressure mercury lamps, high pressure mercury lamps and metal halide lamps.
Although the exposure amount is not particularly limited, it is preferably 5 to 2,000 mJ/cm ² , more preferably 10 to 1,000 mJ/cm ² .
Moreover, it is preferable to heat in order to facilitate alignment of the liquid crystal compound during curing by exposure. The heating temperature may be selected depending on the composition of the liquid crystal compound and the liquid crystal composition used, and is, for example, 60 to 120.degree.

The cholesteric liquid crystal layer preferably has selective reflectivity in a specific wavelength range.
As used herein, the selective reflection wavelength is defined as the half-value transmittance expressed by the following formula, where Tmin (%) is the minimum value of the transmittance of the target object (member): T1/2 (%) and having selective reflectivity means having a specific wavelength range that satisfies the selective reflection wavelength.
Formula for calculating half-value transmittance: T1/2 = 100-(100-Tmin)/2
The selective reflection wavelength in the cholesteric liquid crystal layer is not particularly limited, and can be set, for example, in any range of visible light (380 to 780 nm) and near-infrared light (more than 780 nm and 2,000 nm or less). be.
In particular, the cholesteric liquid crystal layer preferably has selective reflectivity in at least a partial wavelength range of near-infrared light.

The thickness of the cholesteric liquid crystal layer is preferably from 0.05 to 20 μm, more preferably from 0.3 to 15 μm, still more preferably from 0.5 to 9 μm, from the viewpoint of scratch resistance, reflectivity and retroreflectivity. 6 to 3 μm or less is particularly preferred.
When two or more layers of the cholesteric liquid crystal layer are provided, it is preferable that each reflective layer independently has the thickness within the above range.

(Layer containing flat metal particles)
From the viewpoint of reflectivity and retroreflectivity, the reflective layer is preferably a layer containing tabular metal particles.

The flat metal particles are not particularly limited as long as they have two main surfaces, and can be appropriately selected depending on the intended purpose. Examples thereof include polygonal shapes such as triangular and hexagonal shapes, and circular shapes. Among them, a polygonal shape having a hexagonal shape or more or a circular shape is preferable, and a hexagonal shape or a circular shape is more preferable.
In this specification, the circular shape means a length of 50% or more of the average equivalent circle diameter on the main surface when ignoring unevenness of 10% or less of the average equivalent circle diameter of the flat metal particles described later. It means a shape in which one flat metal particle has 0 sides. As the circular flat metal particles, when the flat metal particles are observed from the normal direction of the main surface using a transmission electron microscope (TEM), if the outer periphery has no corners and has a round shape. It is not particularly limited and can be appropriately selected depending on the purpose.

In the present specification, the hexagonal shape means a length of 20% or more of the average equivalent circle diameter on the main surface when ignoring unevenness of 10% or less of the average equivalent circle diameter of the flat metal particles described later. It means a shape in which one flat metal particle has 6 sides. The hexagonal tabular metal particles are not particularly limited as long as they have a hexagonal shape when the tabular metal particles are observed with a TEM from the normal direction of the main surface, and can be appropriately selected depending on the purpose. . The hexagonal tabular metal particles may have hexagonal corners with acute angles or obtuse angles, but the hexagonal corners are all obtuse in that they can reduce absorption in the visible light range. is preferred. The degree of the obtuse angle is not particularly limited and can be appropriately selected according to the purpose.

The material of the tabular metal particles is not particularly limited, and preferably contains at least silver, gold, aluminum, copper, rhodium, nickel, or platinum, and more preferably contains at least silver.

The layer containing flat metal particles may contain metal particles other than flat metal particles. Other metal particle shapes include granular, cubic, hexahedral, octahedral, and rod-like. The material of the other metal particles is not particularly limited and can be appropriately selected according to the purpose, but silver, gold, aluminum, copper, rhodium, nickel, or platinum is preferable, and silver is more preferable.
In the layer containing flat metal particles, the number of flat metal particles is preferably 60 number % or more, more preferably 65 number % or more, and still more preferably 70 number % or more, based on the total number of metal particles. Although the upper limit is not particularly limited, it is preferably 100% by number or less.
The ratio of the number of flat metal particles is determined by observing at least 200 metal particles in the layer containing flat metal particles using an electron microscope (e.g., TEM and SEM), and determining the number of flat metal particles. It is obtained by measuring and calculating the ratio to the total number of metal particles.

The average particle diameter (average equivalent circle diameter) of the tabular metal particles is not particularly limited, but is preferably 10 to 500 nm, more preferably 20 to 300 nm, even more preferably 50 to 200 nm.
The average particle diameter (average equivalent circle diameter) can be obtained by a known method of measuring the projected area of particles on an electron micrograph and correcting the photographing magnification. The equivalent circle diameter is represented by the diameter of a circle having an area equal to the projected area of each grain obtained by this method. The average particle diameter (average equivalent circle diameter) can be determined by arithmetically averaging the equivalent circle diameters D of 500 arbitrarily selected tabular metal particles.

The thickness of the tabular metal particles is not particularly limited, but is preferably 14 nm or less, more preferably 5 to 14 nm, even more preferably 5 to 12 nm, and particularly preferably 5 to 10 nm.
The aspect ratio of the tabular metal particles is not particularly limited, but is preferably 6-40, more preferably 10-35.
The aspect ratio means a value obtained by dividing the average particle diameter (average equivalent circle diameter) of the flat metal particles by the average particle thickness of the flat metal particles. The grain thickness corresponds to the distance between main planes of tabular metal grains, and can be measured by an atomic force microscope (AFM) or TEM.

The method for synthesizing the flat metal particles is not particularly limited, and examples thereof include liquid phase methods such as chemical reduction, photochemical reduction, and electrochemical reduction. Among these, the chemical reduction method and the photochemical reduction method are preferable in terms of shape and size controllability.
After synthesizing hexagonal to triangular tabular metal particles, for example, by performing etching treatment with dissolving species such as nitric acid and sodium sulfite that dissolve silver, aging treatment by heating, etc., hexagonal to triangular tabular particles are obtained. Hexagonal to circular plate-like metal particles may be obtained by blunt the corners of the metal particles.

The layer containing tabular metal particles preferably contains a polymer, and more preferably contains a transparent polymer.
Polymers include polyvinyl acetal resin, polyvinyl alcohol resin, polyvinyl butyral resin, polyacrylate resin, polymethyl methacrylate resin, polycarbonate resin, polyvinyl chloride resin, (saturated) polyester resin, polyurethane resin, and natural polymers such as gelatin and cellulose. are mentioned.
The content of the polymer relative to the metal particles contained in the layer containing flat metal particles is preferably 1 to 10000% by mass, more preferably 10 to 1000% by mass, and even more preferably 20 to 500% by mass.

Plane-oriented flat metal particles in which the angle formed by the main plane of the flat metal particles and the surface of the uneven structure closest to the flat metal particles is in the range of 0° to ±30° is the total flat metal particles. is preferably 50% by number or more. Among them, it is preferable that the flat metal particles that are plane-oriented in the range of 0 to ±20° form an angle of 0 to ±20° and account for 50% by number or more of all the flat metal particles. It is particularly preferable that the tabular metal particles having plane orientation in the range of ±10° account for 50% by number or more of all the tabular metal particles.
FIG. 10 is a diagram for explaining the angle (±θ) formed between the main plane of the flat metal particle (the plane that determines the equivalent circle diameter D) and the surface of the uneven structure that is closest to the flat metal particle. FIG. 10 is a partially enlarged view of the substrate 14 and the reflective layer 16A, which is a layer containing flat metal particles. The angle between the main plane of the particle 22 and the surface of the uneven structure of the reflective layer 16A is indicated by θ.
The surface of the uneven structure closest to the flat metal particle from the main plane of the flat metal particle refers to the surface of the uneven structure closest to the flat metal particle from the main plane of the flat metal particle. It refers to a plane that is perpendicular to the perpendicular line. When the surface of the uneven structure is flat like the prism shape, the angle between the main plane of the flat metal particle and the surface of the uneven structure closest to the flat metal particle is It becomes the surface of the uneven structure including the foot of the perpendicular drawn from the main plane of the flat metal particle toward the surface of the uneven structure closest to the flat metal particle. When the surface of the uneven structure is curved like the hemispherical shape described above, the angle between the main plane of the flat metal particle and the surface of the uneven structure closest to the flat metal particle is A perpendicular drawn from the main plane of the flat metal particle to the surface of the uneven structure closest to the flat metal particle is a tangential plane of the surface of the uneven structure.
As a method for measuring the above-mentioned angle, a cross-sectional sample or a cross-sectional section sample of the laminate is prepared using a microtome or a focused ion beam (FIB), and this is subjected to various microscopes (for example, a field emission scanning electron microscope (FE- SEM), TEM, etc.), and a method of evaluating from an image obtained by observation is exemplified.

Although the thickness of the layer containing tabular metal particles is not particularly limited, it is preferably 5 to 120 nm, more preferably 7 to 80 nm.

(Optical multilayer film)
The reflective layer may be an optical multilayer film (dielectric multilayer film).
The optical multilayer film is a wavelength selective reflection layer including an optical multilayer film that reflects light in a specific wavelength band (first wavelength band) and transmits light in a wavelength band other than the specific wavelength band (second wavelength band). For example, a first refractive index layer (low refractive index layer) and a second refractive index layer (high refractive index layer) having a higher refractive index than the first refractive index layer are alternately laminated. It is formed from a laminated film. Alternatively, when the optical multilayer film selectively reflects infrared light, a metal layer having a high reflectance in the infrared light region and an optically transparent layer having a high refractive index in the visible light region and functioning as an antireflection layer It is formed of a laminated film in which layers or transparent conductive layers are alternately laminated.
Materials for the metal layer with high reflectance in the infrared light region include simple substances such as Au, Ag, Cu, Al, Ni, Cr, Ti, Pd, Co, Si, Ta, W, Mo, and Ge, and and alloys containing two or more of these simple substances.
When an alloy is used as the material for the metal layer, examples of the material for the metal layer include AlCu, AlTi, AlCr, AlCo, AlNdCu, AlMgCu, AgBi, AgPdCu, AgPdTi, AgCuTi, AgPdCa, AgPdMg, and AgPdFe. be done.
Preferably, the optically transparent layer is mainly composed of a high dielectric material such as niobium oxide, tantalum oxide, and titanium oxide.
Materials for the transparent conductive layer include tin oxide, zinc oxide, indium-doped tin oxide (ITO), carbon nanotube-containing materials, indium-doped zinc oxide, and antimony-doped tin oxide. In addition to the above, examples of the transparent conductive layer include a layer in which nanoparticles of the above materials, or nanoparticles, nanorods, or nanowires of a conductive material such as metal are dispersed in a resin at a high concentration. be done.
These optically transparent layers or transparent conductive layers may contain dopants such as Al and Ga. For example, in the case of a ZnO-based oxide, at least one selected from the group consisting of Ga- and Al-doped zinc oxide (GAZO), Al-doped zinc oxide (AZO), and Ga-doped zinc oxide (GZO) Seeds can be used.

Further, the refractive index of the high refractive index layer included in the laminated film is preferably 1.7 to 2.6, more preferably 1.8 to 2.6, even more preferably 1.9 to 2.6. As a result, antireflection in the visible light region can be realized with a thin film that does not cause cracks. Here, the refractive index is at 25° C. and a wavelength of 550 nm.
Examples of the high refractive index layer include a layer containing metal oxide as a main component.
As the metal oxide, metal oxides other than zinc oxide are preferable from the viewpoint of relaxing the stress of the layer and suppressing the generation of cracks. It is preferable to use at least one selected from the group consisting of tantalum) and titanium oxide.
The thickness of the high refractive index layer is preferably 10 to 120 nm, more preferably 10 to 100 nm, even more preferably 10 to 80 nm. Within the above range, the reflection of visible light can be suppressed, the transmittance is excellent, and the occurrence of cracks tends to be suppressed.

The optical multilayer film is not limited to a multilayer film of thin films made of an inorganic material, and may be a film in which a thin film made of a polymer material or a layer in which particles or the like are dispersed in a polymer is laminated.
Methods for forming the optical multilayer film include dry processes such as sputtering and vacuum deposition, and wet processes such as dip coating and die coating.

(layer containing chromic material)
The reflective layer may be a layer containing a chromic material.
The chromic material is a functional layer that reversibly changes reflection performance and the like by an external stimulus, and the layer containing the chromic material may be used as a single layer or multiple layers. They may be used in combination.
Chromic materials are materials that reversibly change their structure due to external stimuli such as heat, light, and invading molecules.
Chromic materials include photochromic materials, thermochromic materials, gaschromic materials, and electrochromic materials.

The laminate may have two or more reflective layers.
Each of the two or more reflective layers may have the same composition or different compositions.

<Refractive index adjustment layer>
The laminate has a refractive index adjusting layer on the reflective layer. The refractive index adjusting layer is arranged on the reflective layer so as to fill the uneven structure of the surface shape of the reflective layer.
As described above, the refractive index adjusting layer is a layer having a refractive index difference of 0.20 or less with respect to the substrate at a wavelength of 550 nm.
As the material constituting the refractive index adjustment layer, a material that satisfies the difference in refractive index from the substrate is appropriately selected. Examples of materials contained in the refractive index adjusting layer include resins. Resins include (meth)acrylic resins, olefin resins, urethane resins, alkyd resins, silicone resins, and melamine resins.

The refractive index adjustment layer may contain other materials besides the resins described above. Other materials include metal oxide particles, since the refractive index of the refractive index adjustment layer can be easily adjusted. Materials constituting the metal oxide fine particles include titanium oxide, zirconium oxide, aluminum oxide, indium oxide, tin-doped indium oxide, zinc oxide, tin oxide, and antimony oxide.

A method for forming the refractive index adjusting layer is not particularly limited, and known methods can be used.
For example, a method of applying a coating liquid for forming a refractive index adjustment layer containing a monomer, and subjecting the coating film to curing treatment (for example, light irradiation treatment and heat treatment) to form a refractive index adjustment layer; A method of forming a refractive index adjusting layer by applying a resin-containing coating liquid for forming a refractive index adjusting layer and drying the coating film may be used.

The thickness of the refractive index adjusting layer is appropriately selected so as to fill the uneven structure of the surface shape of the reflective layer, as described above. Among them, the thickness of the refractive index adjusting layer is preferably 0.1 to 1000 μm, more preferably 0.5 to 700 μm, even more preferably 1 to 500 μm.

<Adhesive layer>
The laminate has an adhesive layer on the refractive index adjusting layer.
Materials contained in the adhesive layer are not particularly limited, and include pressure-sensitive adhesives and adhesives.

Examples of adhesives include acrylic adhesives, rubber adhesives, and silicone adhesives. In addition, as the adhesive, acrylic adhesives and ultraviolet (UV) curable adhesives described in Chapter 2, "Release Paper/Release Film and Adhesive Tape Characteristic Evaluation and Control Technology", Information Organization, 2004 , and silicone adhesives. The acrylic pressure-sensitive adhesive refers to a pressure-sensitive adhesive containing a polymer of (meth)acrylic monomers ((meth)acrylic polymer).
When using an adhesive, a tackifier may be used in combination.

Examples of adhesives include urethane resin adhesives, polyester adhesives, (meth)acrylic resin adhesives, ethylene vinyl acetate resin adhesives, polyvinyl alcohol adhesives, polyamide adhesives, and silicone adhesives. A urethane resin adhesive or a silicone adhesive is preferred because of its higher adhesive strength.

The method of forming the adhesive layer is not particularly limited. Using a transfer film in which an adhesive layer is formed on a temporary support, the adhesive layer and the refractive index adjusting layer are attached so that they are in contact with each other, and the temporary support is formed. Examples include a peeling method, a method of laminating an adhesive layer on the refractive index adjusting layer, and a method of coating an adhesive layer forming coating liquid on the refractive index adjusting layer to form an adhesive layer.

The thickness of the adhesive layer is not particularly limited, and is preferably 15-150 μm, more preferably 20-120 μm, even more preferably 24-80 μm.

<Other layers>
The laminate may include layers other than the above-described layers (protective layer, substrate, reflective layer, refractive index adjusting layer, and adhesive layer).

(Ultraviolet absorption layer)
The laminate may have an ultraviolet absorption layer containing an ultraviolet absorber.
The type of ultraviolet absorber is not particularly limited, and includes the ultraviolet absorbers exemplified for the protective layer described above.
The ultraviolet absorbing layer may contain a binder. The binder is preferably at least one selected from the group consisting of (meth)acrylic resins, polyester resins, urethane resins, olefin resins, siloxane resins, and fluororesins, and (meth)acrylic resins, polyester resins, and urethane resins. and at least one selected from the group consisting of olefin resins, more preferably (meth)acrylic resins.

(Orientation layer)
If the stack has a cholesteric liquid crystal layer as a reflective layer, the stack may have an alignment layer arranged adjacent to the cholesteric liquid crystal layer.
The alignment layer is used to align the molecules of the liquid crystal compound in the liquid crystal composition when forming the layer containing the liquid crystal compound.

The alignment layer can be provided by means such as rubbing treatment of an organic compound (preferably polymer), oblique vapor deposition of an inorganic compound such as SiO, and formation of a layer having microgrooves. Furthermore, examples of the alignment layer include an alignment layer in which an alignment function is produced by application of an electric field, application of a magnetic field, and light irradiation.

In addition, in the laminate, the substrate can be directly subjected to an orientation treatment (for example, rubbing treatment) to function as an orientation layer. One example of such a substrate is polyethylene terephthalate (PET).
In addition, when a cholesteric liquid crystal layer is laminated directly on a cholesteric liquid crystal layer, the lower cholesteric liquid crystal layer may act as an alignment layer to orient the liquid crystal compound for the production of the upper layer. In such a case, the liquid crystal compound in the upper layer can be aligned without providing an alignment layer or performing a special alignment treatment (for example, rubbing treatment).

The thickness of the orientation layer is not particularly limited, and is preferably 0.01 to 10 μm.

Hereinafter, a rubbing-treated alignment layer and a photo-alignment layer, which are used by rubbing the surface, will be described as preferred examples.

Polymers that can be used for the rubbing treatment alignment layer include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohols and modified polyvinyl alcohols, poly(N -methylolacrylamide), polyesters, polyimides, vinyl acetate copolymers, carboxymethylcellulose, and polycarbonates. Also, a silane coupling agent can be used as the polymer.
The polymer is preferably a water-soluble polymer (e.g., poly(N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, or modified polyvinyl alcohol), more preferably gelatin, polyvinyl alcohol, or modified polyvinyl alcohol. Polyvinyl alcohol or modified polyvinyl alcohol is more preferred.

The rubbing treatment can generally be carried out by rubbing the surface of the film containing a polymer as a main component with paper or cloth in one direction. A general rubbing method is described, for example, in "Liquid Crystal Handbook" (published by Maruzen Co., Ltd., Oct. 30, 2000).
As a method for changing the rubbing density, a method described in "Liquid Crystal Handbook" (published by Maruzen Co., Ltd.) can be used. The rubbing density (L) is quantified by the following formula (A).
Formula (A) L=Nl(1+2πrn/60v)
In formula (A), N is the number of rubbing times, l is the contact length of the rubbing roller, r is the radius of the roller, n is the rotation speed (rpm, revolutions per minute) of the roller, and v is the stage moving speed (per second).

In order to increase the rubbing density, it is necessary to increase the number of times of rubbing, lengthen the contact length of the rubbing roller, increase the radius of the roller, increase the rotation speed of the roller, and slow down the stage movement speed. To do this, do the opposite. In addition, the description in Japanese Patent No. 4052558 can be referred to as conditions for the rubbing treatment.

A large number of documents and the like describe photo-alignment materials used in photo-alignment layers formed by light irradiation. For example, JP-A-2006-285197, JP-A-2007-76839, JP-A-2007-138138, JP-A-2007-094071, JP-A-2007-121721, JP-A-2007-140465, JP 2007-156439, JP 2007-133184, JP 2009-109831, JP 3883848, and the azo compounds described in JP 4151746, JP 2002-229039 Aromatic ester compounds described in, JP-A-2002-265541, and maleimide and / or alkenyl-substituted nadimide compounds having photo-orientation units described in JP-A-2002-317013, Patent No. 4205195, and Photocrosslinkable silane derivatives described in Japanese Patent No. 4205198, Japanese Patent Publication No. 2003-520878, Japanese Patent Publication No. 2004-529220, and Japanese Patent No. 4162850, photocrosslinkable polyimides and photocrosslinkable polyamides, Alternatively, a photocrosslinkable polyester may be mentioned.
Among them, an azo compound, a photocrosslinkable polyimide, a photocrosslinkable polyamide, or a photocrosslinkable polyester is preferable.

A photo-alignment layer formed from the above materials is subjected to linearly polarized or non-polarized irradiation to produce a photo-alignment layer.
As used herein, "linearly polarized light irradiation" is an operation for causing a photoreaction in the photoalignment material. The wavelength of the light used for the linearly polarized light irradiation varies depending on the photo-alignment material used, and is not particularly limited as long as the wavelength is required for the photoreaction. Among them, the peak wavelength of light used for light irradiation is preferably 200 to 700 nm, and more preferably ultraviolet light with a peak wavelength of 400 nm or less.

A known light source can be used as a light source for light irradiation. For example, lamps such as tungsten lamps, halogen lamps, xenon lamps, xenon flash lamps, mercury lamps, mercury xenon lamps, and carbon arc lamps, various lasers (e.g., semiconductor lasers, helium neon lasers, argon ion lasers, helium cadmium lasers, YAG lasers), light emitting diodes, and cathode ray tubes.

As means for obtaining linearly polarized light, a method using a polarizing plate (e.g., iodine polarizing plate, dichroic dye polarizing plate, and wire grid polarizing plate), a prism-based element (e.g., Glan-Thompson prism), and Brewster's angle are used. A method using a reflective polarizer or a method using light emitted from a laser light source having polarized light can be used. Alternatively, only light of a required wavelength may be selectively irradiated using a filter, a wavelength conversion element, or the like.

When the light to be irradiated is linearly polarized light, a method of irradiating light perpendicularly or obliquely to the surface of the photo-alignment layer from the upper surface or the back surface of the photo-alignment layer is exemplified. The incident angle of light varies depending on the photo-alignment material, but is preferably 0 to 90° (perpendicular), more preferably 40 to 90°, with respect to the photo-alignment layer.
When using non-polarized light, the non-polarized light is obliquely irradiated. The incident angle is preferably 10 to 80°, more preferably 20 to 60°, even more preferably 30 to 50°.
The irradiation time is preferably 1 to 60 minutes, more preferably 1 to 10 minutes.

The laminate according to the present disclosure may have layers other than those described above.
Other layers include, for example, a self-healing layer, an antistatic layer, an antifouling layer, an anti-electromagnetic layer, and a conductive layer, which are known layers in laminates such as decorative films.

<Method for manufacturing laminate>
The method for producing the laminate is not particularly limited, and a known method can be used, and the laminate can be suitably produced by the method for forming each layer described above.
For example, there is a method of forming a protective layer on a substrate, and then sequentially forming a reflective layer, a refractive index adjusting layer, and an adhesive layer on the surface opposite to the protective layer.
In addition, as described above, in order to form a predetermined concave-convex structure on one surface of the substrate, there is a method of transferring a mold using a mold in which a shape corresponding to the concave-convex structure is formed in advance. More specifically, after forming a coating film of the coating solution for forming a protective layer on the substrate, a reflective layer is formed on the surface opposite to the side on which the coating film is formed to form the reflective layer. Using a mold in which a shape corresponding to the concave-convex structure is previously formed on the other surface, the concave-convex structure is transferred to one surface of the substrate and the reflective layer. After that, a refractive index adjusting layer and an adhesive layer are formed on the reflective layer, and the coating layer on the substrate is cured to form a protective layer to form a laminate. be done.

Further, when the coating solution for forming a protective layer contains a curable component, after coating the coating solution for forming a protective layer on a substrate, the coating film may be subjected to a curing treatment, or various layers may be formed, Finally, the coating film of the coating liquid for forming the protective layer may be subjected to a curing treatment.

The laminate may be molded into a predetermined shape by a known method, if necessary. As the molding, at least one molding selected from the group consisting of three-dimensional molding and insert molding is suitable.

The use of the laminate obtained as described above is not particularly limited, and it can be used for various articles, but it is particularly suitable for the interior and exterior of automobiles, the interior and exterior of electrical appliances, packaging containers, and the like. mentioned. Among them, automobile interior and exterior members are preferred, and automobile exterior members are more preferred.

EXAMPLES The present disclosure will be described in detail below with reference to Examples, but the present disclosure is not limited to these. In the present examples, "%" and "parts" mean "% by mass" and "parts by mass", respectively, unless otherwise specified.

<Production Example 1: Preparation of coating liquid for metal particle-containing layer>
(Preparation of silver tabular particle dispersion liquid A)
13 L of ion-exchanged water was weighed into a reaction vessel made of high Cr--Ni--Mo stainless steel (NTKR-4, manufactured by Nippon Metal Industry Co., Ltd.). 10 g/L of trisodium citrate (anhydrous Item) 1.0 L of the aqueous solution was added and the liquid temperature was maintained at 35°C. 0.68 L of 8.0 g/L polystyrene sulfonic acid aqueous solution was added to the above solution, and 0.68 L of sodium borohydride aqueous solution adjusted to a concentration of 23 g/L using 0.04 mol/L sodium hydroxide aqueous solution. 041 L was added to the above solution. 13 L of 0.10 g/L silver nitrate aqueous solution was added to the above solution in the reaction vessel at 5.0 L/min to prepare a seed solution.
1.0 L of 10 g/L trisodium citrate (anhydrous) aqueous solution and 11 L of deionized water were added to the above seed solution, and 0.68 L of 80 g/L potassium hydroquinonesulfonate aqueous solution was further added. After increasing the stirring speed to 800 rpm (rounds per minute) and adding 8.1 L of 0.10 g/L silver nitrate aqueous solution to the reaction vessel at 0.95 L/min, the temperature was lowered to 30°C.
8.0 L of 44 g/L methylhydroquinone aqueous solution was added to the reaction vessel, and then the whole amount of 40° C. gelatin aqueous solution described later was added to the reaction vessel. The stirring speed was increased to 1,200 rpm, and the entire amount of the silver sulfite white precipitate mixture described later was added to the reaction vessel.
When the pH change of the preparation liquid stopped, 5.0 L of 1 mol/L sodium hydroxide (NaOH) aqueous solution was added to the preparation liquid at 0.33 L/min. Then, 2.0 g / L of 1-(m-sulfophenyl)-5-mercaptotetrazole sodium aqueous solution (NaOH and citric acid (anhydride) are used to adjust the pH to 7.0 ± 1.0 and dissolve ) 0.18 L was added, and 70 g/L of 1,2-benzisothiazolin-3-one (dissolved by adjusting the aqueous solution to alkalinity with NaOH.) 0.078 L was added to the preparation solution, A silver tabular grain dispersion liquid A was prepared.

(Preparation of aqueous gelatin solution)
16.7 L of ion-exchanged water was weighed into a dissolution tank made of SUS316L (austenitic stainless steel). 1.4 kg of deionized alkali-treated bovine bone gelatin (weight average molecular weight by GPC: 200,000) was added to the dissolution tank while stirring at a low speed with a SUS316L stirrer. Further, 0.91 kg of alkali-treated bovine bone gelatin (weight-average molecular weight by GPC: 21,000), which had been deionized, protease-treated and oxidized with hydrogen peroxide, was added to the dissolution tank. Thereafter, the temperature was raised to 40° C., and gelatin was swollen and dissolved at the same time to dissolve completely, thereby preparing an aqueous gelatin solution.

(Preparation of silver sulfite white precipitate mixture)
8.2 L of ion-exchanged water was weighed into a SUS316L dissolution tank, and 8.2 L of a 100 g/L silver nitrate aqueous solution was added to the dissolution tank. 2.7 L of a 140 g/L sodium sulfite aqueous solution was added to the above solution in a short time while stirring at high speed with a SUS316L stirrer to prepare a mixed solution containing a white precipitate of silver sulfite. This mixture was prepared immediately before use.

When the silver tabular particle dispersion liquid A was diluted with ion-exchanged water and the spectral absorption was measured using a spectrophotometer (U-3500 manufactured by Hitachi, Ltd.), the absorption peak wavelength was 900 nm and the full width at half maximum was 270 nm. Met.
The physical properties of the silver tabular particle dispersion liquid A are pH = 9.4 at 25°C (measured with KR5E manufactured by AS ONE Corporation), electrical conductivity of 8.1 mS/cm (measured with CM-25R manufactured by Toa DKK Corporation). ) and a viscosity of 2.1 mPa·s (measured with SV-10 manufactured by A&D Co., Ltd.). The obtained silver tabular particle dispersion liquid A was placed in a 20 L container of Union Container Type II (made of low-density polyethylene, sold by AS ONE Corporation) and stored at 30°C.

(Preparation of silver tabular particle dispersion liquid B)
800 g of the silver tabular particle dispersion A was collected in a centrifugal tube (container for centrifuge), and 1N (mol/L) NaOH and/or 1N (mol/L) sulfuric acid was added to the dispersion A. was adjusted to have a pH of 9.2±0.2 at 25°C. Using a centrifuge (himac CR22GIII, angle rotor R9A, manufactured by Hitachi Koki Co., Ltd.), the temperature was set to 35 ° C., 9,000 rpm, and after performing centrifugation for 60 minutes, 784 g of the supernatant was discarded. . A 0.2 mmol/L NaOH aqueous solution was added to the precipitated tabular grains to make a total of 400 g, and stirred with a stirring rod to prepare a coarse dispersion. A coarse dispersion for 24 centrifuge tubes was prepared by the same operation, and a total of 9,600 g of the coarse dispersion was added to a tank made of SUS316L and mixed. Further, 10 ml of a 10 g/L solution (diluted with a mixed solution of methanol:ion-exchanged water=1:1 (volume ratio)) of a nonionic surfactant (“Pluronic 31R1” manufactured by BASF) was added to the tank. The crude dispersion mixture in the tank was subjected to batch-type dispersion treatment at 9,000 rpm for 120 minutes using an Automixer Model 20 (manufactured by Primix Co., Ltd., stirring unit: Homomixer MARK II). The temperature of the crude dispersion mixture was kept at 50°C during dispersion. Next, the resulting dispersion was cooled to 25° C. and subjected to single-pass filtration using a Profile II filter (manufactured by Nippon Pall Co., Ltd., product model MCY1001Y030H13).

In this manner, the silver tabular particle dispersion A was subjected to desalting treatment and redispersion treatment to prepare a silver tabular particle dispersion B.
When the spectral transmittance of the silver tabular particle dispersion liquid B was measured in the same manner as for the silver tabular particle dispersion liquid A, the results of absorption peak wavelength and half width were almost the same as those of the silver tabular particle dispersion liquid A.
The physical properties of the silver tabular particle dispersion liquid B were pH=7.6 at 25° C., electrical conductivity of 0.37 mS/cm, and viscosity of 1.1 mPa·s. The resulting silver tabular particle dispersion B was placed in a Union Container II type 20 L container and stored at 30°C.

(Evaluation of tabular metal particles)
It was confirmed using an image obtained by TEM observation of the silver tabular particle dispersion A that hexagonal to circular and triangular tabular metal particles were formed in the silver tabular particle dispersion A. . In addition, the number of hexagonal to circular flat metal particles was determined based on the shapes of 200 flat metal particles arbitrarily extracted from the SEM image of observing the silver flat particle dispersion liquid A. Image analysis was performed with the shape of the flat plate-like metal particles as A and the triangular plate-like metal particles as B, and the ratio (% by number) of the number of hexagonal or circular plate-like metal particles corresponding to A was determined. As a result, it was found to be 80% by number or more of all flat metal particles (hexagonal or circular flat metal particles and triangular flat metal particles).
An image obtained by TEM observation of the silver tabular particle dispersion liquid A was taken into image processing software ImageJ and subjected to image processing. Image analysis was performed on 500 particles arbitrarily extracted from TEM images of several fields of view, and the equivalent circle diameter of the same area was calculated. Statistical processing based on these populations resulted in an average diameter of 120 nm.
The silver tabular particle dispersion liquid A was measured using a laser diffraction/scattering particle size/particle size distribution measuring device Microtrac MT3300II (manufactured by Nikkiso Co., Ltd., particle permeability set to reflection), and the average particle size (volume weighted) gave a result of 51 nm.
When the silver tabular particle dispersion liquid B was measured in the same manner, the ratio of the tabular metal particles to the total metal particles, the particle size distribution and shape of the tabular metal particles were compared with the total metal particles of the tabular metal particles in the silver tabular particle dispersion liquid A. Almost the same results as those of the ratio of the tabular metal particles and the particle size distribution and shape of the tabular metal particles were obtained.
The silver tabular grain dispersion liquid B was dropped onto a silicon substrate and dried, and the thickness of each silver tabular grain was measured by the FIB-TEM method. Ten silver tabular grains in the silver tabular grain dispersion liquid B were measured and the average thickness was 8 nm.

(Preparation of coating solution for forming metal particle-containing layer)
A coating liquid for forming a metal particle-containing layer having the composition shown below was prepared.
Water-based urethane resin: Hydran HW350 (manufactured by DIC Corporation, solid content 30% by mass): 0.27 parts by mass Silver tabular particle dispersion liquid B: 17.85 parts by mass 1-(methylureidophenyl)-5- Mercaptotetrazole (manufactured by Wako Pure Chemical Industries, Ltd., preparing an alkaline aqueous solution with a solid content of 2% by mass): 0.61 parts by mass Surfactant A (Ripal 870P (manufactured by Lion Corporation, solid content of 1% by mass ion Exchanged water dilution)): 0.96 parts by mass Surfactant B (Naroacty CL-95 (manufactured by Sanyo Chemical Industries, Ltd., solid content 1% by mass, diluted with ion-exchanged water)): 1.19 parts by mass Methanol : 30.00 parts by mass Distilled water: 49.12 parts by mass

<Production Example 2: Preparation of coating solution for forming alignment layer>
A coating solution for forming an alignment layer having the composition shown below was prepared.
・Modified polyvinyl alcohol represented by the following formula (the number at the bottom right of each structural unit in the following formula represents the molar ratio.): 28 parts by mass ・Citrate ester (AS3, manufactured by Sankyo Chemical Co., Ltd.): 1.2 parts by mass Photopolymerization initiator (IRGACURE 2959, manufactured by BASF): 0.84 parts by mass Glutaraldehyde: 2.8 parts by mass Water: 699 parts by mass Methanol: 226 parts by mass

<Production Example 3: Preparation of Coating Liquid for Forming Cholesteric Liquid Crystal Layer>
A coating liquid for forming a cholesteric liquid crystal layer having the composition shown below was prepared.
· Methyl ethyl ketone: 150.6 parts by mass · Liquid crystal compound 1 (rod-shaped liquid crystal compound): 100.0 parts by mass · Photopolymerization initiator A (IRGACURE 907, manufactured by BASF): 0.50 parts by mass · Chiral agent A: 4. 00 parts by mass and the following surfactant F1: 0.027 parts by mass

Liquid crystal compound 1 (monofunctional): The following rod-like liquid crystal compound. In the case of a radical polymerization system, even if it has an oxetanyl group (cationically polymerizable functional group), it has only one acryloxy group (radical polymerizable group), so it is defined as monofunctional. The same applies to cationic polymerization systems.

Chiral agent A (bifunctional): the following compound

Surfactant F1: the following compound

<Production Example 4: Preparation of coating solution for forming protective layer>
75 parts by mass of methyl methacrylate and 88 parts by mass of glycidyl methacrylate were covalently used with a radical polymerization initiator V-601 (dimethyl 2,2'-azobis(isobutyrate), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). polymerized. Acrylate-modified acrylic resin A was obtained by reacting 50 parts by mass of the obtained polymer with 19.2 parts by mass of acrylic acid in the presence of tetraethylammonium chloride. The weight average molecular weight was 20,000. The acrylate functional amount (the amount of structural units having acryloxy groups obtained by reacting acrylic acid with structural units derived from glycidyl methacrylate relative to the total resin) was 30% by mass.

By stirring and mixing the following materials at 25° C. for 24 hours, a hydrolyzate 1 of an acrylate-modified siloxane oligomer was obtained.
-composition-
・Acryloyloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.): 15.0 parts by mass ・Methyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.): 6.0 parts by mass ・Ethanol (FUJIFILM Wako Pure Chemical Industries, Ltd.) Co., Ltd.): 17.5 parts by mass Acetic acid (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.): 3.6 parts by mass Water: 11.7 parts by mass

Further, the following was stirred and mixed at 25° C. for 24 hours to obtain a coating liquid for forming a protective layer.
・Hydrolyzate 1: 8.0 parts by mass ・Ethanol: 8.0 parts by mass ・Acrylate-modified acrylic resin A (weight average molecular weight = 20,000): 11 parts by mass ・Ultraviolet (UV) absorber (Tinuvin479-DW, BASF Corporation, solid content 40% by mass): 1 part by mass Acrylic resin (methyl methacrylate (MMA) / methacrylic acid (MAA) = 60/40 (mass ratio), Aldrich Co., Mn = 32,000): 6 parts by mass IRGACURE 127 (radical photopolymerization initiator, manufactured by BASF): 0.1 parts by mass F-553 (fluorosurfactant manufactured by DIC Corporation): 0.02 parts by mass

<Production Example 4: Preparation of coating liquid 1 for forming refractive index adjustment layer>
A coating liquid 1 for forming a refractive index adjustment layer having the composition shown below was prepared.
・Acrylic polymer aqueous dispersion (AS-563A (manufactured by Daicel Finechem Co., Ltd., solid content 27.5% by mass)): 20 parts by mass ・Crosslinking agent (Carbodilite V-02-L2 (manufactured by Nisshinbo Chemical Co., Ltd., solid concentration 20% by mass diluted with distilled water)): 0.46 parts by mass Surfactant A (Ripal 870P (manufactured by Lion Corporation, 1% by mass solid content diluted with distilled water)): 0.63 parts by mass Surfactant Agent B (Naroacty CL-95 (manufactured by Sanyo Chemical Industries, Ltd., solid content 1% by mass, diluted with distilled water)): 0.87 parts by mass Urethane polymer aqueous solution (Orester UD350 (manufactured by Mitsui Chemicals, Inc., solid 38% by mass)): 0.13 parts by mass Distilled water: 77.91 parts by mass

<Production Example 5: Preparation of coating liquid 2 for forming refractive index adjustment layer>
0.17 parts by mass of a titanium oxide dispersion (Snowtex ST-50-T, manufactured by Nissan Chemical Industries, Ltd.) was added to the coating liquid 1 for forming a refractive index adjustment layer to prepare a coating liquid 2 for forming a refractive index adjustment layer. bottom.

<Production Example 6: Preparation of Coating Liquid 3 for Forming Refractive Index Layer>
3.07 parts by mass of a titanium oxide dispersion (Snowtex ST-50-T, manufactured by Nissan Chemical Industries, Ltd.) was added to the refractive index adjusting layer forming coating solution 1 to prepare a refractive index adjusting layer forming coating solution 3. bottom.

<Production Example 7: Preparation of coating liquid 4 for forming refractive index adjustment layer>
7.24 parts by mass of a titanium oxide dispersion (Snowtex ST-50-T, manufactured by Nissan Chemical Industries, Ltd.) was added to the refractive index adjusting layer forming coating solution 1 to prepare a refractive index adjusting layer forming coating solution 4. bottom.

<Example 1>
On one side of an acrylic resin substrate (Sumitomo Chemical Co., Ltd., Technolloy S001G), a coating solution for forming a protective layer was applied using a wire bar coater, and the coating film was dried at 120 ° C. for 2 minutes to obtain a thickness of 15 μm. A coating film was formed. Next, a UV exposure apparatus (GS Yuasa, nitrogen purge UV irradiation machine, metal halide lamp, output 120 W/cm ² ) is used to apply an integrated exposure amount of 1,000 mJ/cm ² to the obtained coating film. This provided a protective layer.
On the surface of the acrylic resin substrate opposite to the protective layer side, using a wire bar, the coating liquid for forming a metal particle-containing layer was applied so as to be 10.6 ml / m ² , and the coating film Then, a layer containing flat metal particles (hereinafter also simply referred to as "metal particle-containing layer") was provided. The film thickness of the metal particle-containing layer after coating and drying was 20 nm.
A mold having a hemispherical convex portion with a depth of 25 μm as shown in FIGS. (manufactured by Toyo Seiki Co., Ltd.), by hot pressing at 140 ° C. and 10 MPa, an acrylic resin base material having a concave-convex structure on one surface side of the acrylic resin base material and the concave-convex structure are arranged to follow. A laminated body having a metal particle-containing layer that was coated with the metal particles was obtained.
All the flat metal particles of the flat metal particles are planarly oriented at an angle of 0° to ±30° between the principal plane of the flat metal particles and the surface of the uneven structure closest to the flat metal particles. The proportion to the particles was 95 number %.

Next, the coating liquid 1 for forming a refractive index adjusting layer is applied to the metal particle-containing layer side of the obtained laminate using a wire bar so that the uneven structure is buried, and the coating film is dried at 80°C. was applied to provide a refractive index adjusting layer 1. The refractive index difference between the refractive index adjustment layer 1 and the acrylic resin base material was 0.01.

Next, on the refractive index adjustment layer 1, a comma coater is used to apply an acrylic pressure-sensitive adhesive liquid (Sokken Chemical Co., Ltd., SK Dyne SG-50Y), and the coating film is dried at 120 ° C. for 2 minutes. An adhesive layer having a thickness of 25 μm was formed.

<Example 2>
Instead of using a metal particle-containing layer, a cholesteric liquid crystal layer formed by carrying out the method for forming a cholesteric liquid crystal layer described later is used, and the depth of the hemispherical protrusions as shown in FIGS. is 25 μm, a corner cube mold (depth: 100 μm) as shown in FIG. 6 and FIG. A laminate 2 was obtained in the same manner as in Example 1, except that the layer-forming coating liquid 3 was used.

(Method for Forming Cholesteric Liquid Crystal Layer)
On the surface of the acrylic resin substrate opposite to the protective layer side obtained by the procedure of Example 1, a coating solution for forming an alignment layer is applied using a wire bar, and the coating is dried at 100° C. for 120 seconds. Thus, an alignment layer having a layer thickness of 1.5 μm was formed.
Next, rubbing treatment (rayon cloth, pressure: 0.1 kgf (0.98 N), number of revolutions: 1,000 rpm) is performed on the alignment film in a direction rotated counterclockwise by 31.5° with respect to the short side direction. , conveying speed: 10 m/min, number of reciprocations: 1).
A coating solution for forming a cholesteric liquid crystal layer prepared using a wire bar coater was applied to the surface of the alignment layer that had undergone rubbing treatment, and the coating film was dried at 85° C. for 120 seconds. Furthermore, using a UV exposure apparatus (GS Yuasa, nitrogen purge UV irradiation machine, metal halide lamp, output 120 W/cm ² ), the temperature of the coating film was kept at 80° C., and 500 mJ/cm ² was applied to the coating film. By giving an integrated exposure amount of , the film was cured to obtain a cholesteric liquid crystal layer.

<Example 3>
Instead of the corner cube mold, a mold having a hemispherical convex portion with a depth of 25 μm as shown in FIGS. A laminate 2 was obtained in the same manner as in Example 2, except that the layer-forming coating liquid 2 was used.

<Example 4>
A laminate 4 was obtained in the same manner as in Example 1, except that the coating liquid for forming a protective layer was used instead of the coating liquid 1 for forming a refractive index adjustment layer.

<Example 5>
Instead of using a cholesteric liquid crystal layer, a dielectric multilayer film formed by carrying out a method for forming a dielectric multilayer film described later is used , and the depth of the hemispherical protrusions as shown in FIGS. Laminate 5 was produced according to the same procedure as in Example 1 , except that a corner cube mold (depth: 100 μm) as shown in FIGS. 6 and 7 was used instead of the mold with a thickness of 25 μm. Obtained.

(Method for forming dielectric multilayer film)
Nb ₂ O ₅ (115 nm), SiO ₂ (175 nm), Nb 2 O 5 (115 nm), Nb ₂ O ₅ (115 nm), and A dielectric multilayer film was formed by depositing SiO ₂ (175 nm) and Nb ₂ O ₅ (115 nm) sequentially.

<Example 6>
A laminate was prepared according to the same procedure as in Example 1, except that a pyramid-shaped prism-shaped mold as shown in FIGS. got 6.

<Comparative Example 1>
A laminate C1 was obtained in the same manner as in Example 1, except that the coating liquid 4 for forming a refractive index adjustment layer was used instead of the coating liquid 1 for forming a refractive index adjustment layer.

<Comparative Example 2>
A laminate C2 was obtained according to the same procedure as in Example 1, except that the metal particle-containing layer was not provided.

<Comparative Example 3>
A laminate C3 was obtained in the same manner as in Example 1, except that the protective layer was not provided.

<Evaluation>
(retroreflectance)
When light with a wavelength of 850 to 950 nm was incident from a direction inclined by 45° from the normal direction of the surface of the laminate obtained, the intensity (Is) of light reflected in the incident direction of the light was measured.
A white diffuser plate made of barium sulfate was used instead of the laminate, and the same measurement as above was performed to measure the strength (Ii).
The retroreflectance (%) at each wavelength is defined as Is/Ii×100 and calculated. The maximum value of retroreflectance at each wavelength was selected.
In the above measurement, more specifically, the laminate was irradiated with light from a light source (HL-2000-HP-FHSA, manufactured by Ocean Optics) through an optical fiber (VIS/NIR 200 μm Q/BIF, manufactured by Ocean Optics). , the light reflected at the same angle was led again to the detector (Photonic Multi-Channel Analyzer C7473-36, manufactured by Hamamatsu Photonics Co., Ltd.) through an optical fiber, and the amount of light was measured.

(LiDAR detection)
First, as a LiDAR sensor, a LiDAR kit 905 nm type manufactured by triMATIZ was prepared.
Next, a measurement sample 1 of 1.4 cm square and a measurement sample 2 of 1.4 cm long and 2.0 cm wide were cut out from the obtained laminate.
The LiDAR sensor and the measurement sample 1 were placed 5 m apart. At that time, the LiDAR sensor was arranged so that the light emitted from the LiDAR was incident on the measurement sample 1 from the normal direction of the surface of the measurement sample 1 . Scanning was performed in this state to determine whether or not the measurement sample 1 could be detected by the LiDAR sensor 10 times, and evaluation was made according to the following criteria.
Also, the LiDAR sensor and the measurement sample 2 were placed 5 m apart. At that time, the LiDAR sensor was arranged so that the light emitted from the LiDAR was incident on the measurement sample 2 from a direction inclined by 45° from the normal direction of the surface of the measurement sample 2 . Scanning was performed in this state, and measurement was performed 10 times to determine whether or not the measurement sample 2 could be detected by the LiDAR sensor, and evaluation was made according to the following criteria.
A: 10 measurements can be made and detected 10 times.
B: It can be detected 1 to 9 times or more in 10 measurements.
C: Not detectable after 10 measurements.

(elastic modulus)
The modulus of elasticity of each layer was measured using a dynamic ultra-micro hardness tester (DUH-201S, manufactured by Shimadzu Corporation). For the measurement of each layer, the surface of each layer was subjected to the above measurements for the protective layer and the adhesive layer. For the other layers, the cross section of the laminate was cut, or the layer to be measured was exposed by cutting or the like.
The measurement conditions are as follows.
・Type of indenter: Vickers
・Test mode: load-unload test ・Test force: 40mN
・Load speed: 1.3239mN/sec
・Holding time: 5 sec

(optical properties)
The reflectance and transmittance of the obtained laminate in each wavelength range were measured with an ultraviolet-visible-near-infrared spectrophotometer (manufactured by Shimadzu Corporation, UV-3100PC).

(Haze)
The haze of the obtained laminate was measured with NDH5000 manufactured by Nippon Denshoku Industries Co., Ltd.

(Scratch resistance)
A test piece with a thickness of 7 cm and a width of 5 cm was cut out from the obtained laminate, and the reflectance of the surface of the test piece (hereinafter also simply referred to as "reflectance before test") was measured by the same method as the above reflection characteristic evaluation. Measured by
Next, a gravelometer (manufactured by Suga Test Instruments Co., Ltd., JA-400S type) was used on the surface of the protective layer side of the obtained test piece under a test temperature of 0 ° C. and a pressure of 0.3 MPa. 100 g of No. 7 crushed stone was collided with. After that, the reflectance of the surface of the test piece (hereinafter also simply referred to as “post-test reflectance”) was measured by the same method as the reflection characteristic evaluation described above.
Next, the ratio (%) of the absolute value of the difference between the reflectance before the test and the reflectance after the test to the reflectance before the test [{(reflectance before test - reflectance after test) / (reflectance after test Reflectance before)}×100] was obtained, and the scratch resistance of the laminate was evaluated based on the following criteria.
A: Decrease in reflectance is less than 30% before test B: Decrease in reflectance is 30% or more and less than 50% before test C: Decrease in reflectance is 50% or more before test

The refractive index of the refractive index adjusting layer is determined by forming a refractive index adjusting layer with a thickness in the range of 200 to 800 nm on a Si substrate, and measuring the refractive index of the refractive index adjusting layer at a wavelength of 550 nm with an ellipsometer (manufactured by JASCO Corporation, M150). It was measured.
The refractive index of the base material (acrylic resin base material) is obtained by dissolving the base material in a solvent and spin-coating it onto the Si substrate to form a film for refractive index measurement with a thickness in the range of 200 to 800 nm. Then, the refractive index of the refractive index measurement film (substrate) at a wavelength of 550 nm was measured with an ellipsometer (manufactured by JASCO Corporation, M150).

In Table 1, the "500 to 600 nm" column in the "R/T" column represents the maximum value of the ratio of the reflectance to the transmittance at each wavelength in the wavelength range of 500 to 600 nm.
In Table 1, the "850 to 950 nm" column represents the maximum value of the ratio of reflectance to transmittance at each wavelength in the wavelength range of 850 to 950 nm.
In Table 1, "refractive index difference" represents the difference in refractive index at a wavelength of 550 nm between the substrate and the refractive index adjusting layer.
In Table 1, in the "reflective layer" column, "particle layer" represents a layer containing flat metal particles, and "CL layer" represents a cholesteric liquid crystal layer.
In Table 1, the "transmittance @ 550 nm" column represents the transmittance of the laminate at a wavelength of 550 nm.
In Table 1, the "reflectance @ 905 nm" column represents the reflectance of the laminate at a wavelength of 905 nm.

As shown in Table 1, the desired effect was obtained with the laminate of the present invention.

REFERENCE SIGNS LIST 10 laminate 12 protective layer 14 substrate 16, 16A reflective layer 18 refractive index adjusting layer 20 adhesive layer 22 flat metal particles

Claims (5)

a protective layer;
a substrate having an uneven structure on the surface opposite to the protective layer;
a reflective layer disposed on the surface having the uneven structure of the base material and having a surface shape of the uneven structure that follows the uneven structure;
a refractive index adjusting layer disposed on the reflective layer and filling the uneven structure of the reflective layer;
and an adhesive layer in this order,
a difference in refractive index at a wavelength of 550 nm between the substrate and the refractive index adjusting layer is 0.20 or less;
When measuring the ratio of reflectance to transmittance at each wavelength in the wavelength range of 500 to 600 nm, the maximum value of the ratio is 0.20 or less,
A laminate having a maximum value of 0.40 or more when measuring the ratio of reflectance to transmittance at each wavelength in the wavelength range of 850 to 950 nm ,
When E1 is the elastic modulus of the protective layer, E2 is the elastic modulus of the substrate, E3 is the elastic modulus of the refractive index adjusting layer, and E4 is the elastic modulus of the adhesive layer, the following formula (1) and satisfies the relationship of formula (2),
The elastic modulus E1 of the protective layer is 3 to 15 GPa,
The elastic modulus E2 of the base material is 0.3 to 5 GPa,
The elastic modulus E3 of the refractive index adjusting layer is 0.3 to 1 GPa,
The elastic modulus E4 of the adhesive layer is 0.0002 GPa to 0.01 GPa,
The laminate, wherein the protective layer has a thickness of 1 to 25 μm.
Formula (1) E1>E2>E4
Formula (2) E1>E3>E4 2. The laminate according to claim 1 , wherein the reflective layer is a layer selected from the group consisting of a cholesteric liquid crystal layer and a layer containing tabular silver particles. The laminate according to claim 1 or 2 , wherein the uneven structure has a corner cube shape, a pyramid shape, or a hemispherical shape. The laminate according to any one of claims 1 to 3 , wherein the uneven structure has a depth of 1 µm or more. Claims 1 to 4 , wherein the maximum value of retroreflectance at each wavelength is 10% or more when light with a wavelength of 850 to 950 nm is incident from a direction inclined 45° from the normal direction of the laminate. The laminate according to any one of the above.

Images