Laminate including colloidal crystal layer

Abstract

To provide means for achieving further structural color development.SOLUTION: A laminate having a substrate, a colloidal crystal layer, and a protective layer, wherein the laminate has adjacent first and second regions, the first region has a first reflectance peak wavelength for incident light, the second region has a second reflectance peak wavelength for the incident light, the first reflectance peak wavelength and the second reflectance peak wavelength are different wavelengths, the first region has a first colloidal crystal layer containing first fine particles, the second region has a second colloidal crystal layer containing second fine particles, and shapes of the first fine particles and the second fine particles are different.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminate that exhibits structural coloring. [Background technology]

[0002] Structural coloring refers to the coloring phenomenon caused by microscopic structures at or below the wavelength of light. Familiar examples of structural color include compact discs, soap bubbles, morpho butterflies, and jewel beetles. These objects themselves are not colored, but appear colored because light is reflected and interfered by their microscopic structures. In recent years, development has been progressing to artificially create regular structures that exhibit structural color.

[0003] For example, Non-Patent Document 1 proposes a nano-laminated film with a metallic luster, in which polymers of different components are laminated in more than 1,000 layers within the thickness of the film. It also mentions that the transmission and reflection of light from visible light to near-infrared can be freely controlled for each wavelength. Patent Document 1 also proposes a method for producing a cholesteric liquid crystalline film by forming a film made of a liquid crystalline polymer on a substrate. It mentions that when the reflected light wavelength is in the visible range, the reflected light or transmitted light exhibits a vivid color, and therefore the film can be used as a decorative material. In addition, various methods have been proposed for producing laminates in which the particles are regularly arranged in the planar direction on a substrate, for example, by using a dispersion in which monodisperse particles are dispersed in a medium, pouring the dispersion, and then arranging, aligning, drying, and fixing the particles by spraying, coating, flow, etc. Colloidal crystals are known as such regularly arranged particles, and it is known that such colloidal crystals exhibit Bragg reflection and exhibit structural colors. Research and development has been conducted to apply this to colorants and decorative films. As a method for forming colloidal crystals to exhibit structural colors, Patent Document 2 proposes a method for inexpensively forming colloidal crystals using only coating, using core-shell particles consisting of a core and a shell, and utilizing the fluidity of the shell, which fuses together when heated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-186534 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-249527 [Non-patent literature]

[0005] [Non-Patent Document 1] Toray Industries, Inc. (2016). JETI, Vol. 64, No. 8, 71-73 Summary of the Invention [Problem to be solved by the invention]

[0006] However, although the method proposed in Non-Patent Document 1 is groundbreaking in that it allows for the production of 1,000 or more layers in a single thin film within the film manufacturing process without the need for subsequent lamination, there has been a demand for a simpler method for obtaining a laminate that exhibits structural coloring. Furthermore, there is no sufficient description of the effects on coloring of stretching and compression, which are necessary for applying the laminate as a decorative film. Furthermore, although the method proposed in Patent Document 1 allows a laminate that exhibits structural coloring to be easily obtained by coating and drying, it does not provide sufficient information on the effects of stretching and compression on coloring, which are necessary for applying the layered product as a decorative film. Furthermore, the method proposed in Patent Document 2 does not provide sufficient description regarding the influence of stretching and compression on color development, which is necessary for applying the laminate as a decorative film. The present inventors aim to find further means for manifesting structural coloration. [Means for solving the problem]

[0007] As a result of extensive research into solving the above problems, the present inventors have found that the above problems can be solved by carrying out processing means such as stretching or compression, and have arrived at the present invention.

[0008] That is, the present invention has the following features. [1] A laminate having a substrate, a colloidal crystal layer, and a protective layer, the laminate having adjacent first and second regions, the first region having a first reflectance peak wavelength for incident light, the second region having a second reflectance peak wavelength for the incident light, the first reflectance peak wavelength and the second reflectance peak wavelength being different wavelengths, the first region having a first colloidal crystal layer containing first microparticles, the second region having a second colloidal crystal layer containing second microparticles, and the first microparticles and the second microparticles having different shapes. [2] The laminate according to [1], wherein the first fine particles have the same composition as the second fine particles. [3] The laminate according to [1], wherein the first fine particles contain a polymer containing a structural unit derived from styrene and a structural unit derived from acrylic acid. [4] The laminate according to [1], wherein the first colloidal crystal layer and the second colloidal crystal layer are continuously formed layers. [5] A method for manufacturing a laminate, comprising the steps of forming a laminate including a colloidal crystal layer and a protective layer on a substrate, and processing the laminate to form a first region and a second region, wherein the first region has a first reflectance peak wavelength for incident light and the second region has a second reflectance peak wavelength for the incident light, the first reflectance peak wavelength and the second reflectance peak wavelength are different wavelengths, the first region has a first colloidal crystal layer including first microparticles, and the second region has a second colloidal crystal layer including second microparticles, and the first microparticles and the second microparticles have different shapes. [6] The method for producing a laminate according to [5], wherein the processing treatment is a process for stretching a part of the laminate. [7] The method for producing a laminate according to [5], wherein the processing treatment is a process of compressing a portion of the laminate. [Effects of the Invention]

[0009] By employing processing means such as stretching or compression, the laminate of the present invention can exhibit a structural color different from the structural color before the processing means, resulting in a laminate with excellent design. Specifically, by using a laminate having adjacent first and second regions, each having its own colloidal crystal layer, and each region having a different reflectance peak wavelength for incident light, different structural colors are generated in the first and second regions, resulting in an excellent design. [Brief explanation of the drawings]

[0010] [Figure 1] (a) and (b) are schematic diagrams of the laminate according to the present invention before and after stretching. [Figure 2] (a)(b) Schematic diagrams of the laminate according to the present invention before and after compression [Figure 3] TEM tomographic image of the first region (stretched portion) of the laminate in Example 1 [Figure 4] TEM tomographic image of the second region (non-stretched portion) of the laminate in Example 1 [Figure 5] TEM tomographic image of the first region (compressed portion) of the laminate in Example 3 [Figure 6] TEM tomographic image of the second region (uncompressed portion) of the laminate in Example 3 [Figure 7] TEM image of the first region (stretched portion) of the laminate in Comparative Example 1 [Figure 8] Cross-sectional TEM photograph of the second region (non-stretched portion) of the laminate in Comparative Example 1 DETAILED DESCRIPTION OF THE INVENTION

[0011] The following describes in detail the embodiments of the present invention. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to the following content as long as it does not exceed the gist of the present invention. Furthermore, when the expression "to" is used in this specification, it is intended to include the numerical values ​​or physical values ​​written before and after it. Furthermore, numerical values ​​or physical values ​​written as upper and lower limits are intended to include those values.

[0012] This invention relates to a laminate having a substrate, a colloidal crystal layer, and a protective layer, and more specifically, to a laminate comprising a substrate, a colloidal crystal layer that develops color due to the interference of light, and a protective layer for immobilizing the colloidal crystal layer, arranged in that order. The laminate has adjacent first and second regions, the first region having a first reflectance peak and the second region having a second reflectance peak, the first reflectance peak and the second reflectance peak being different, and the particles constituting the first and second regions have different shapes. The adjacent first and second regions can be formed by stretching or compressing a portion of the laminate. The particles are deformed by stretching or compressing, resulting in different shapes for the particles constituting the first and second regions.

[0013] <Base material> The substrate is a material that serves as the base of the laminate, and is not particularly limited, and general materials such as metal, resin, wood, and paper can be used. For example, thermoplastic resin substrates such as polyvinyl chloride sheets, polyester films such as polyethylene terephthalate (PET), polypropylene films, polyethylene films, nylon films, polystyrene films, and polyvinyl alcohol films, metal substrates such as aluminum foil, glass substrates, and coated paper substrates can also be used.

[0014] The substrate may have a smooth or uneven surface, and may be transparent, translucent, or opaque. It is also possible to use a substrate that has been pre-colored, such as black. Two or more of the above substrates may be laminated together. The substrate may be subjected to a corona treatment or plasma treatment in advance to improve the coatability of the dispersion of the present invention. A primer layer may be provided on the substrate. When the deformation of the fine particles is performed by stretching, the storage modulus of the substrate at 120°C, which is near the molding temperature, is 1.0 × 10 8 Pa, and preferably less than 1.0 × 10 7 It is more preferable that the viscosity is less than 1.0×10 Pa. 8 By making the compressive strength less than Pa, a laminate with excellent moldability can be obtained.

[0015] [Protective layer] The protective layer is a layer for immobilizing and protecting the colloidal crystal layer of the laminate, and is made of a material that forms a film on the surface of the colloidal crystal layer. In addition to covering the surface of the fine particles, the protective layer is preferably filled between the fine particles that form the colloidal crystal layer. There are no particular restrictions on the material of the protective layer, as long as it can deform the fine particles into a non-spherical shape by stretching or compressing. Examples of resins constituting the protective layer include acrylic resins, acrylic urethane resins, silicone resins, and epoxy resins. From the viewpoint of facilitating deformation of the microparticles into a non-spherical shape by stretching or compressing, the storage modulus of the protective layer at 120°C, which is near the molding temperature, is set to 1.0 × 10 8 Pa, and preferably less than 1.0 × 10 7 It is more preferable that the pressure is less than 100 Pa. The resin constituting the protective layer is generally in the form of a resin precursor that can be cured by heat or light, a resin solution diluted with an arbitrary solvent, or an emulsion dispersed in water.

[0016] The thickness of the protective layer is not particularly limited, provided that it is equal to or greater than the thickness that covers the fine particles of the layer made of colloidal crystals. The protective layer can be formed on the surface of the colloidal crystal layer by applying a thin film of a resin precursor, resin solution, or emulsion that can be cured by heat or light onto the colloidal crystal layer, and then subjecting it to light irradiation, heat treatment, or the like as necessary.

[0017] <Fine particles> The colloidal crystals are obtained by crystallizing fine particles in a colloidal state. The fine particles used in the present invention preferably have a volume average particle size of 180 to 800 nm and a CV value of particle size based on number of 15% or less.

[0018] [Volume average particle size] The volume-based average particle diameter (volume average particle diameter) of the fine particles is preferably 180 nm or more, preferably 190 nm or more, more preferably 200 nm or more, and even more preferably 210 nm or more. It is also preferably 800 nm or less, preferably 780 nm or less, more preferably 750 nm or less, and even more preferably 700 nm or less. A volume average particle diameter within the above range is preferable because it improves the structural color development of the resulting laminate and improves the design properties. Furthermore, a volume average particle diameter within the above range can be said to be a colloid. The method for measuring the volume average particle diameter in the present invention is as described in the Examples, and the volume median diameter was used as the volume average particle diameter.

[0019] [CV value of particle size based on number] The CV value of the particle size based on the number of particles of the present invention is preferably 15% or less, preferably 10% or less, and more preferably 5% or less. There is no particular restriction on the lower limit of the CV value of the particle size based on the number, but it is usually 1% or more. If the CV value of the particle size based on the number is within the above range, it is preferable because the design properties are good. The CV value is also called the "coefficient of variation" or "relative standard deviation," and in the present invention means the relationship between the standard deviation in the particle size distribution based on the number and the number average particle size, (standard deviation / number average particle size) x 100 It is calculated as follows. The microparticles have the CV value of the particle diameter based on the number as described above, and therefore, when a colloidal crystal layer is formed using the raw material microparticles by the method described below, the colloidal crystals are arranged in a regular pattern, which can produce structural coloring and contribute to improved design.

[0020] [Type and structure of particles] The fine particles have a volume average particle size and a CV value of particle size based on number within the above ranges. There are no particular limitations on the fine particles, so long as they are solid organic fine particles.

[0021] [Fine particle materials] Examples of materials constituting the organic fine particles include polymeric organic materials, such as polyolefins, polystyrenes, poly(meth)acrylics, styrene-(meth)acrylic copolymers, polyamides, polyimides, polyvinyl chloride, phenolic resins, and polycarbonates. Among these polymer materials, polymers with a high refractive index are preferred because they increase the difference in refractive index between the particles and the protective layer described below, thereby improving structural coloring. Furthermore, these polymer materials may be non-crosslinked or crosslinked polymers.

[0022] (Polyolefins) Examples of the polyolefins include polyethylenes such as low-density polyethylene and high-density polyethylene, polypropylene, and ethylene-propylene copolymers.

[0023] (Polystyrenes) The polystyrenes are polymers whose main component is a styrene unit, where the main component means that the content of the styrene unit relative to the entire polymer is 50% by mass or more, and further 60% by mass or more. The polystyrenes may be either random copolymers or block copolymers, but are generally random copolymers. The polystyrenes may be copolymerized with any monomer in addition to styrene.

[0024] Examples of the optional monomer include styrenes other than styrene, such as methylstyrene and chlorostyrene; metal salts such as sodium salt of styrenesulfonic acid; acidic monomers such as acrylic acid and methacrylic acid; (meth)acrylic acid esters such as methyl (meth)acrylate and ethyl (meth)acrylate; and acrylamides such as acrylamide, N-propylacrylamide, and diacetone acrylamide. Among these, metal salts such as sodium styrenesulfonate are preferred because they allow for good control of particle size, and diacetone acrylamide is preferred because it can increase the strength of the colloidal crystal layer by reacting it with, for example, adipic acid dihydrazide between particles. When a crosslinked structure is to be introduced into polystyrenes, a known polyfunctional monomer may be copolymerized.

[0025] The polystyrene preferably contains 80.0 to 99.75% by mass of styrene units. If the content of styrene units is within the above range, the refractive index of the particles is increased, and structural coloring is improved, which is preferable. The content of styrene units is more preferably 90.0% by mass or more, and more preferably 99.4% by mass or less.

[0026] The polystyrene preferably contains 0.25 to 20.0 mass % of acidic monomer units such as acrylic acid units, methacrylic acid units, etc. If the content of the acidic monomer units is within the above range, cullets during polymerization are reduced, which is preferable. The content of the acidic monomer unit is more preferably 0.6% by mass or more, and more preferably 10.0% by mass or less.

[0027] When the polystyrenes contain any monomer unit other than the acidic monomer unit and / or polyfunctional monomer unit, the content thereof is preferably 3% by mass or less, more preferably 2% by mass or less. If the content is 3% by mass or less, the particle size can be well controlled.

[0028] (Poly(meth)acrylics) Poly(meth)acrylics are polymers whose main components are (meth)acrylic acid ester units or (meth)acrylic acid units. Here, the term "main component" means that the content of (meth)acrylic acid ester units in the entire polymer is 50% by mass or more, and more preferably 60% by mass or more.

[0029] Examples of the (meth)acrylic acid ester that serves as a raw material for the (meth)acrylic acid ester unit include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate. Furthermore, examples of the raw material for the (meth)acrylic acid unit include (meth)acrylic acid.

[0030] The poly(meth)acrylics may be either random copolymers or block copolymers, but are generally random copolymers. The poly(meth)acrylics may be copolymerized with any monomer in addition to the above-mentioned (meth)acrylic acid esters and (meth)acrylic acid. Examples of this optional monomer include styrenes such as styrene and methylstyrene; metal salts such as sodium salt of styrenesulfonic acid; acrylamides such as acrylamide, N-propylacrylamide, and diacetoneacrylamide; and styrene-(meth)acrylic copolymers described below.

[0031] (Styrene-(meth)acrylic copolymers) Styrene-(meth)acrylic copolymers are polymers whose main component is a copolymer of styrene units with (meth)acrylic acid ester units or (meth)acrylic acid units. Here, the term "main component" means that the content of the copolymer relative to the entire polymer is 50% by mass or more, and more preferably 60% by mass or more. The monomer constituting the styrene unit, the monomer constituting the (meth)acrylic acid ester unit, and the monomer constituting the (meth)acrylic acid unit can be the monomer constituting the styrene unit, the (meth)acrylic acid ester unit, and the (meth)acrylic acid unit described above.

[0032] The content of styrene units constituting the styrene-(meth)acrylic copolymers in the styrene-(meth)acrylic copolymers is preferably 50% by mass or more, and more preferably 60% by mass or more. Also, it is preferably 99% by mass or less, and more preferably 98% by mass or less. By keeping it within this range, the refractive index of the particles can be increased, and the characteristic of more vivid structural coloring can be exhibited.

[0033] Among these, metal salts such as sodium styrenesulfonate are preferred because they allow for good control of particle size, and diacetone acrylamide is preferred because it can increase the strength of the colloidal crystal layer by reacting it with, for example, adipic acid dihydrazide between particles. When a crosslinked structure is to be introduced into the poly(meth)acrylic acid ester, a known polyfunctional monomer may be copolymerized.

[0034] (Preferred particulate material) Among the above-mentioned materials, poly(meth)acrylic acid esters and polystyrenes are preferred because raw materials are easily available and it is easy to produce fine particles with a uniform particle size, and polystyrenes are more preferred because they can produce polymers with a high refractive index.

[0035] [Production of fine particles] The colloidal crystal layer of the present invention exhibits structural color when regularly arranged, and therefore it is important that the colloidal crystals forming the colloidal crystal layer are fine particles that satisfy the volume average particle size and the CV value of the particle size based on the number as described above and have a uniform particle size.

[0036] To obtain organic fine particles having a volume average particle size and a CV value of the particle size based on the number, for example, a method of obtaining a polymer of an appropriate size by bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization, etc., pulverizing the polymer into a fine powder, and then sieving the powder to obtain a uniform particle size can be used. Another method is to directly obtain organic fine particles having a uniform particle size by soap-free emulsion polymerization. Among these, the method using soap-free emulsion polymerization is preferred because of its excellent productivity. This soap-free emulsion polymerization is a known polymerization method, for example, as follows. Deionized water is charged into a reaction vessel, and while heating and stirring as necessary, a polymerization aid is added to thoroughly disperse the polymerization aid in the deionized water. Next, a polymerization initiator is added while continuing to stir. Then, while continuing to stir, the monomers are gradually added dropwise to initiate the polymerization reaction. As the polymerization proceeds, particles are formed.

[0037] The solid concentration during polymerization, that is, the concentration of fine particles relative to the entire system during polymerization, is preferably 20 to 40% by mass. If the solid content concentration during polymerization is equal to or higher than the lower limit, productivity of organic fine particles is improved, and if it is equal to or lower than the upper limit, no cullet is generated during polymerization and no deposits are formed on the inner walls of the polymerization apparatus. When a polymerization initiator is used, the polymerization temperature is generally set to 60 to 90° C. After the reaction is completed, organic fine particles are taken out as an emulsion.

[0038] The pH of the emulsion is preferably 3.0 to 11.0 If the pH of the emulsion is outside the above range, productivity will be poor from the viewpoint of metal corrosion. Therefore, if the pH of the emulsion is outside the above-mentioned preferred range, it is preferable to adjust the pH by adding an alkali or acid as appropriate. Since the pH of the emulsion obtained by the production of the organic fine particles is usually about 2.0 to 7.0, the pH is generally adjusted by adding an alkali. The alkali used for pH adjustment is preferably ammonia water, as it can be easily removed from the colloidal crystal layer by heating or the like.

[0039] Examples of polymerization initiators used in soap-free emulsion polymerization include water-soluble polymerization initiators such as sodium persulfate, potassium persulfate, and ammonium persulfate; oil-soluble polymerization initiators such as benzoyl peroxide and lauryl peroxide; and redox-based polymerization initiators formed by combining an oxidizing agent and a reducing agent. These may be used alone or in combination of two or more. Among these, water-soluble polymerization initiators are preferred because they are easy to handle.

[0040] <Dispersion> In the present invention, a microparticle dispersion (hereinafter simply referred to as "dispersion") is obtained by incorporating the microparticles and a dispersion medium. Here, the dispersion means a dispersion liquid in which microparticles are dispersed in a dispersion medium.

[0041] Any medium can be used as the dispersion medium, including, for example, water, aqueous media such as media mainly composed of water, and organic solvents. A medium mainly composed of water means that the water ratio is 50% by mass or more, and even 60% by mass or more. As a component other than water, any organic solvent soluble in water can be selected.

[0042] Examples of organic solvents include alcohols such as methanol, ethanol, isopropyl alcohol, and 1-methoxy-2-propanol alcohol, ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, aromatic solvents such as toluene and xylene, ester-based solvents such as ethyl acetate and butyl acetate, alkanes such as hexane, cyclohexane, heptane, decane, and hexadecane, halogen-based solvents such as methyl chloride, methylene chloride, chloroform, and carbon tetrachloride, and ether-based solvents such as tetrahydroxyfuran, dioxane, ethylene glycol diethyl ether, and ethylene glycol monobutyl ether. These may be used alone or in combination of two or more. Among the above, aqueous media such as water and media mainly containing water are preferred as the dispersion medium, as they are likely to give a colloidal crystal layer with high structural color development.

[0043] The content of the fine particles in the dispersion of the present invention is 1% by mass to 70% by mass based on the total mass of the dispersion. % is preferred. The content of the fine particles is preferably 10% by mass or more, more preferably 15% by mass or more, and particularly preferably 20% by mass or more, based on the total mass of the dispersion, and more preferably 45% by mass or less, more preferably 40% by mass or less, and particularly preferably 35% by mass or less. If the content of the fine particles is within the above range, the structural color development of the resulting colloidal crystal layer will be good. A dispersant such as sodium dodecyl sulfate or sodium dodecylbenzenesulfonate may be added to the dispersion. When adding this dispersant, it is sufficient if the content is about 0.001% by mass to 5% by mass of the mass of the fine particles contained in the dispersion. If the content is less than this, the effect of improving the dispersibility of the dispersion, which is sought by adding the dispersant, may not be sufficient. On the other hand, although a larger content may be used, the effect relative to the amount used will not be sufficient, and a content of 5% by mass is sufficient.

[0044] [Dispersion concentration] The solid content of the dispersion of the present invention is preferably 10% by mass or more. The solid content of the dispersion is preferably 20% by mass or more, more preferably 25% by mass or more, and the upper limit of the solid content of the dispersion is preferably 60% by mass or less, more preferably 50% by mass or less. When the solid content concentration of the dispersion is within the above range, film-forming properties are good, and the structural color development of the resulting colloidal crystal film is good. Here, the solid content of the dispersion refers to the components other than the dispersion medium in the dispersion, and is usually the total of the fine particles and other components that may be contained as needed. The solids concentration of the dispersion can be measured in the same manner as the solids concentration of the emulsion described in the Examples section below, but it can also be calculated from the solids concentration and component amounts of each component used in producing the dispersion.

[0045] [Viscosity of dispersion] The viscosity of the dispersion of the present invention is 11.0 cP or less, which results in good structural color development of the resulting colloidal crystal layer. The viscosity of the dispersion of the present invention is preferably 10 cP or less, more preferably 8.0 cP or less, and even more preferably 5.0 cP or less, while the viscosity of the dispersion of the present invention is preferably 1.0 cP or more, more preferably 1.5 cP or more, and even more preferably 2.0 cP or more. Here, the viscosity of the dispersion is the viscosity at 25° C. The viscosity of the dispersion can be measured using, for example, a Brookfield viscometer.

[0046] [Other ingredients] The dispersion of the present invention may contain, in addition to the fine particles and dispersion medium, other components such as a water-soluble resin, a crosslinking agent, a plasticizer, a film-forming aid, and a pH adjuster, as necessary, as long as the object of the present invention is not impaired. By including the water-soluble resin, the affinity between the dispersion and the substrate can be improved, which results in the dispersion having excellent film-forming properties. The water-soluble resin is a polymer compound that dissolves in water or at least disperses in water.

[0047] Examples of the water-soluble resin include resins that have an ionic group such as a sulfonyl group or a carboxyl group, or a water-soluble substituent such as a hydroxyl group in the molecule, and that dissolve in water. The water-soluble resins include non-ionic water-soluble resins and ionic water-soluble resins. Examples of the nonionic water-soluble resin include water-soluble polyacrylamide, water-soluble acrylic resin, nonionic polyvinyl alcohol resin, polyvinylpyrrolidone, polyethylene oxide, polyvinyl acetate; and natural polymer compounds such as starch, gelatin, and casein.

[0048] Examples of the ionic water-soluble resin include water-soluble polyester resin, polyacrylic acid, ionic polyvinyl alcohol resin, and carboxymethyl cellulose. Among these, it is preferable to use a nonionic polyvinyl alcohol resin and / or an ionic polyvinyl alcohol resin because the polymer main chain has high resistance to hydrolysis.

[0049] (ionic water-soluble resin) Next, the ionic water-soluble resin will be described in detail. The ionic water-soluble resin is a water-soluble resin having an anionic or cationic moiety, and specific examples thereof include the above-mentioned resins. Among the ionic water-soluble resins, ionic polyvinyl alcohol resins are preferred because they have improved ionic strength and excellent solvent resistance.

[0050] (ionic polyvinyl alcohol resin) The ionic polyvinyl alcohol resin is a polyvinyl alcohol resin containing an ionic group such as a sulfonyl group or a salt thereof, a carboxyl group or a salt thereof, or a quaternary ammonium salt in the molecular chain.

[0051] Specific examples of ionic polyvinyl alcohol resins include polyvinyl alcohol resins containing sodium salts of sulfonyl groups in the molecular chain, and polyvinyl alcohol resins containing sodium salts of carboxyl groups in the molecular chain. Among these, polyvinyl alcohol resins containing sodium salts of sulfonyl groups are preferred because the salts are easily dissociated. An example of a commercially available ionic polyvinyl alcohol resin is Gohsenex (specially modified polyvinyl alcohol resin, manufactured by Mitsubishi Chemical Corporation).

[0052] The inclusion of the crosslinking agent allows the reactive functional groups of the microparticles to react with the crosslinking agent to form crosslinks, thereby chemically bonding the microparticles together. This improves the heat resistance and physical durability of the resulting colloidal crystal layer. Any compound that is reactive with the reactive functional groups introduced into the microparticles can be used as the crosslinking agent. For example, if diacetone acrylamide is used as a monomer during microparticle synthesis and a keto group is introduced into the microparticles as a reactive group, a multifunctional hydrazide compound such as adipic acid dihydrazide is preferred as the crosslinking agent.

[0053] [Method for preparing dispersion] The dispersion of the present invention can be prepared by mixing the fine particles, the dispersion medium, and other components such as a water-soluble resin and a crosslinking agent, which are used as needed. For example, it can be prepared by mixing the emulsion containing fine particles produced by the above-mentioned method, a dispersion medium, and other components such as a water-soluble resin and a crosslinking agent, which are used as needed.

[0054] <Manufacturing of laminated bodies and colloidal crystal layers> Examples of the method for producing the laminate of the present invention and the method for forming the colloidal crystals include the following methods. The dispersion containing the fine particles is applied onto the substrate, and then dried at an appropriate temperature, thereby aligning the fine particles.

[0055] The method for applying the dispersion to the substrate can be any of printing methods that do not use a plate, such as inkjet, spray, dipping, or spin coating, and printing methods that use a plate, such as an offset gravure coater, gravure coater, doctor coater, bar coater, blade coater, flexo coater, or roll coater.

[0056] The coating thickness of the dispersion of the present invention varies depending on the solids concentration of the dispersion, but is preferably 1 to 100 μm, more preferably 5 to 50 μm, and even more preferably 10 to 30 μm. When the coating thickness is 1 μm or more, the structural coloring properties of the resulting laminate are improved. When the coating thickness is 100 μm or less, the ordered arrangement of the colloidal crystal layers of the resulting laminate is improved, and the structural coloring properties are improved.

[0057] There are no particular limitations on the drying method used after coating the dispersion of the present invention on a substrate, and any conventionally known method can be used, such as heat drying, hot air drying, infrared drying, microwave drying, drum drying, etc. The above drying methods may be used alone or in combination. If the drying temperature is too high, the dispersion medium will volatilize rapidly, disrupting the alignment of the microparticles and adversely affecting color development. On the other hand, if the drying temperature is too low, uneven drying may occur, making it impossible to obtain a uniform colloidal crystal film. From the viewpoint of the alignment of the microparticles, the drying temperature is preferably in the range of 10 to 120°C, particularly 90 to 110°C. The drying time varies depending on the drying temperature, but from the viewpoint of the alignment of the fine particles, it is preferably 0.5 to 30 minutes, more preferably 1 to 10 minutes. The laminate according to the present invention can be obtained by the above method, and the aligned fine particles can be dried by the above method to form a colloidal crystal layer.

[0058] A protective layer is formed to cover the resulting colloidal crystal layer. For example, the protective layer can be formed by applying a precursor of the material constituting the protective layer, a heated fluid, a resin solution diluted with a solvent, or an emulsion of a resin dispersed in water to the surface of the colloidal crystal layer, followed by curing, cooling, drying, etc.

[0059] The wavelength of the maximum reflectance in the reflection spectrum for incident light (hereinafter referred to as the "peak reflectance wavelength") of the obtained laminate is within the visible light range, and therefore, as described below, the structural color is exhibited. Note that the maximum reflectance in the reflection spectrum for incident light is the reflectance derived from Bragg reflection. Next, a portion of the resulting laminate is subjected to processing such as stretching or compression. This processing changes the shape of the fine particles that make up the colloidal crystals in the processed portion, changing the peak wavelength of reflectance for incident light. This allows the laminate to exhibit a structural color different from that before processing, resulting in a product with excellent design properties.

[0060] The stretching treatment is carried out by pinching both ends of the portion of the laminate to be stretched and stretching it. That is, as shown in Figure 1(a), the obtained laminate 11 is composed of a substrate 12, a colloidal crystal layer made of fine particles 13, and a protective layer 14, and both ends of the portion of the laminate to be stretched are pinched and stretched. This stretching treatment results in a stretched portion of the laminate (first region A) and an unstretched region (second region B), as shown in Figure 1(b). By this stretching treatment, as shown in FIG. 1(b), the fine particles in the stretched portion are deformed and become fine particles 13a elongated in the stretching direction, and a partially stretched laminate 11a is obtained.

[0061] This stretching treatment is preferably performed to stretch the laminate to at least 1.1 times the length of the portion of the laminate to be stretched. It is preferably stretched 1.5 times or more, and more preferably 5.0 times or less, and even more preferably 3.0 times or less. By setting the stretching ratio within this range, a structural color different from that before deformation is developed, and an excellent design can be achieved.

[0062] The compression process is performed by compressing the portion of the laminate to be compressed. That is, as shown in Fig. 2(a), the portion of the laminate to be compressed is compressed. This compression process results in a compressed portion of the laminate (first region A') and an uncompressed region (second region B), as shown in Fig. 2(b). By this compression treatment, as shown in FIG. 2(b), the particles in the compressed portion are deformed to become particles 13b compressed in the compression direction, and a partially compressed laminate 11b is obtained.

[0063] This compression treatment is preferably performed to a thickness of 0.99 times or less, preferably 0.98 times or less, based on the thickness of the protective layer in the laminate to be compressed. Also, compression is preferably performed to a thickness of 0.5 times or more, preferably 0.55 times or more. By keeping the compression ratio within this range, a different structural color is developed compared to before deformation, resulting in an excellent design.

[0064] Through the above-described processing, the laminate has adjacent first and second regions. The first region forms a first colloidal crystal layer containing first particles, and the second region forms a second colloidal crystal layer containing second particles, with the first and second colloidal crystal layers being continuously formed layers. Furthermore, the shapes of the first and second particles differ. Therefore, the first reflectance peak wavelength generated in the first region for incident light and the second reflectance peak wavelength generated in the second region for incident light are different wavelengths, and therefore different structural colors can be exhibited in the first region and the second region. The color of this structural color can be adjusted by changing the processing conditions. It should be noted that the first region and the second region are formed by processing the single laminate, and therefore the first fine particles and the second fine particles have the same composition.

[0065] <Structural coloring> The fine particles of the present invention have structural coloring properties when formed into a colloidal crystal layer. Structural coloring means that structural color is exhibited when fine particles of uniform particle diameter are regularly arranged. Structural coloring is a phenomenon in which a material has a crystalline structure in which fine particles are regularly arranged, and optical physical phenomena such as interference and scattering occur depending on the wavelength of light, causing the material to appear colored.

[0066] Since structural coloring is due to the properties of light, it appears not only in the visible light region but also in the ultraviolet and infrared regions. To produce structural colors in the ultraviolet region, fine particles with a small volume average particle diameter should be used, and to produce structural colors in the infrared region, fine particles with a large volume average particle diameter should be used. In the present invention, structural coloring is utilized to improve the design of the article, and therefore it is preferable that the structural color be expressed in the visible light region. Here, the visible light region refers to wavelengths of 360 to 830 nm, the ultraviolet region refers to wavelengths of 200 to 359 nm, and the infrared region refers to wavelengths of 831 to 2500 nm.

[0067] [Colloidal crystal layer] The colloidal crystal layer of the present invention refers to a substance that exhibits structural color, in which the fine particles contained in the dispersion are regularly arranged, specifically a substance containing colloidal aggregates that exhibit structural color. Here, the colloidal aggregate refers to a colloidal crystal or colloidal amorphous aggregate, and at least a portion of the colloidal crystal is contained. By arranging the fine particles, the fine particles form a colloidal crystal or colloidal amorphous aggregate, i.e., a colloidal aggregate. Furthermore, a material that exhibits structural color is one in which fine particles of uniform diameter are regularly arranged, causing diffraction and interference of light, resulting in an angle-dependent color that appears to change depending on the viewing angle.

[0068] Examples of the colloidal crystal layer include a substrate on which fine particles are arranged, and a substrate on which fine particles are arranged, from which colloidal crystals have been peeled off without damaging the regular arrangement of the fine particles.

[0069] In one embodiment, the colloidal crystal layer of the present invention is characterized by containing fine particles having a volume-average particle size of 180 to 800 nm and a CV value of particle size on a number basis of 15% or less. In this case, the fine particles contained in the colloidal crystal layer preferably have the same properties as the fine particles in the dispersion of the present invention described above, and more preferable ranges can also be considered similar.

[0070] [Reflectance of colloidal crystal layer] The colloidal crystal layer of the present invention preferably has a reflectance derived from structural coloring of 5% or more in the wavelength range of 200 to 2500 nm. The reflectance of the colloidal crystal layer can be increased to 5% or more by using, for example, the dispersion of the present invention. The reflectance is more preferably 10% or more, and even more preferably 20% or more. If the reflectance is 5% or more, it is preferable because the structural coloring property is excellent. There is no particular upper limit to the reflectance resulting from the structural coloring of the colloidal crystal layer of the present invention, but it is usually 90% or less. The reflectance due to structural coloring can be measured by the method described in the Examples below.

[0071] [Application] The laminate of the present invention has good structural color development properties because the colloid layers are regularly arranged. Due to these characteristics, the film is suitable for use in decorative films such as color sheets and decorative films; and optical materials such as reflective displays, discoloration sensors, anti-counterfeiting agents, electrodeposited color plates, color filters, and polarizing films. The laminate of the present invention can also be suitably used, either alone or as a secondary processed material, for decorative films such as color sheets and decorative films; and optical materials such as reflective displays, discoloration sensors, anti-counterfeiting agents, electrodeposited color plates, color filters, and polarizing films. [Example]

[0072] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist of the invention is not exceeded. In the following description, "parts" and "%" indicate "parts by mass" and "% by mass", respectively.

[0073] [Evaluation method] In the following examples and comparative examples, various physical properties were measured by the following methods. (1) Volume average particle size of fine particles In the present invention, the volume median diameter is used as the volume average particle diameter. Measurements were performed using NanotracWave II manufactured by Microtrac Bell Co., Ltd. and the company's analysis software, Microtrac Date Management System. Specifically, 0.2 g of the particle dispersion was mixed with 20 mL of diluted sodium dodecylbenzenesulfonate (concentration: 0.02%) and 30 mL of the diluted solution to prepare a sample dispersion. The dispersion was placed in a sample cell and measured under the following conditions: solvent refractive index: 1.333, measurement time: 180 seconds, number of measurements: 1. Other conditions were: particle refractive index: 1.59, transparency: transparent, shape: spherical, density: 1.00.

[0074] (2) CV value of particle size based on the number of fine particles After applying the microparticle dispersion to a substrate and drying, the microparticles were imaged using an electron microscope with a magnification of 20,000 or more. The diameters of at least 400 microparticles in the image were measured, and the arithmetic average was calculated to determine the number-average particle diameter. Then, the CV value of the particle diameter based on the number was calculated by multiplying the standard deviation by the number-average particle diameter by 100.

[0075] (3) Solids concentration of dispersion The solid content concentration of the dispersion was determined by heating 3 g of the dispersion at 190° C. for 60 minutes to evaporate the water using a heat-drying moisture meter MX-50 manufactured by A&D Corporation.

[0076] (4) Stretching the laminate The prepared laminate was stretched using a tension and compression universal testing machine (Shimadzu Corporation, Autograph AGX-5KNNVD (load cell 5KN)) connected to a tension and compression universal testing machine thermostatic chamber unit (Shimadzu Corporation, TCR-2W-P). Specifically, the prepared laminate was cut into a size of 100 mm x 40 mm and fixed with a gripper (Shimadzu Corporation, manual screw-type flat gripper) installed so that the chuck distance was 45 mm. After the temperature in the thermostatic chamber unit of the tension / compression universal testing machine reached the set value of 150°C, the laminate was stretched one minute until the chuck distance reached 67.5 mm. The tension speed at this time was 200 mm / min. After stretching, the stretched laminate was cooled to room temperature to obtain a sample.

[0077] (5) Compression of the laminate The laminate was sandwiched between an aluminum plate, a silicone sheet, a laminate, a silicone sheet, and an aluminum plate, and then heat-pressed using a small heat press machine manufactured by Taiyo Co., Ltd. (upper and lower iron plate temperatures: 110°C, press pressure: 0.1 MPa, press time: 1 minute). The aluminum plate and silicone sheet used were as follows. Aluminum plate: "Aluminum plate H305" manufactured by Kyūho Metal Works Silicone sheet: "Silicone rubber sheet" manufactured by Wake Sangyo Co., Ltd.

[0078] (6) Reflectance peak wavelength The reflection spectrum of the prepared laminate was measured in the wavelength range of 330 to 800 nm using an ultraviolet-visible-near-infrared spectrophotometer (JASCO Corporation: V-770) and an absolute reflectance measurement unit (JASCO Corporation: ARSN-917). The mirror in the absolute reflectance measurement unit (JASCO Corporation: ARSN-917) was used as a reference in the measurements. The maximum value of reflectance in the obtained reflection spectrum is the reflectance derived from Bragg reflection, and the wavelength at this point is the reflectance peak wavelength. Note that the perpendicular direction to the laminate was set as the reference (0°), and both the incident angle and reflection angle were set to 10°.

[0079] (7) Observation of the cross section of the colloidal crystal layer To enable cross-sectional observation, small pieces were cut from the sample and embedded in epoxy resin to create specimen blocks. After trimming the specimen blocks, ultrathin sections were prepared under liquid nitrogen using an ultramicrotome (UC6+FC6) and a diamond knife, and then collected on copper grids. The copper grids were stained with ruthenium tetroxide and then observed using a transmission electron microscope (TEM) as described below. The TEM images were taken at low magnification (1000x on the instrument) to check the state of the sections and to check for overlapping of the sections. A smooth area with no cracks was selected and photographed. ○Equipment used Transmission electron microscope (TEM): JEOL JEM-1400Plus Ultramicrotome: LEICA EM UC6 Ultramicrotome cryochamber: LEICA EM FC6 Diamond knife: Simtec SYM2045T Ultra

[0080] [Raw materials, etc.] The raw materials used in the following examples and comparative examples are as follows. Sodium p-styrenesulfonate (Fujifilm Wako Pure Chemical Industries, Ltd.) Sodium bicarbonate (Fujifilm Wako Pure Chemical Industries, Ltd.) Styrene (Fujifilm Wako Pure Chemical Industries, Ltd.) Acrylic acid (Fujifilm Wako Pure Chemical Industries, Ltd.) Diacetone acrylamide (Fujifilm Wako Pure Chemical Industries, Ltd.) Adipic acid dihydrazide (Tokyo Chemical Industry Co., Ltd.) Ammonium persulfate (Fujifilm Wako Pure Chemical Industries, Ltd.) Ionic polyvinyl alcohol (Mitsubishi Chemical: Gohsenex CKS50) Silicone elastomer 1 (Dow Chemical Company: SYLGARD 184, base and curing agent) Mix the agent at a ratio of 10:1 (by mass) Silicone elastomer 2 (main agent) (Dow Chemical Company: DOWSIL2014Adhes ive) and curing agent (Dow Chemical Company: SRX212 Catalyst) mixed at a mass ratio of 100:0.65 Silica particle water dispersion (Fuji Chemical Co., Ltd.: Houtform Silbol-EX250, silica particles: solid particles)

[0081] [Preparation of Microparticle Dispersion 1] An auxiliary solution was prepared by dissolving 0.98 parts of sodium p-styrenesulfonate and 1.5 parts of sodium hydrogencarbonate in 2095 parts of ion-exchanged water. Also, 881 parts of styrene and 13.2 parts of acrylic acid were mixed to obtain a monomer mixture. The auxiliary agent solution was charged into a reaction vessel equipped with a stirrer, a heating / cooling device, a nitrogen introducing device, and a raw material / auxiliary agent charging device, and the internal temperature was raised to 77°C. Next, a polymerization initiator solution prepared by dissolving 3.8 parts of ammonium persulfate in 7 parts of ion-exchanged water was added to the reaction vessel, and 5 minutes later, the monomer mixture was successively added dropwise over 180 minutes. Thereafter, stirring was continued at 77° C. for 30 minutes, and then the internal temperature was raised to 90° C. Thereafter, stirring at 90° C. was maintained for 3 hours. After cooling the internal temperature to 20°C, the polymerization reaction product was filtered through nonwoven gauze (product name "Cross Gauze No. 2", manufactured by Osaki Medical Co., Ltd.) to obtain a dispersion of microparticles. The pH of the dispersion was adjusted to 7.0 by adding 10 wt% ammonia water. Furthermore, ion-exchanged water was appropriately added to adjust the solid concentration to 29.0%, thereby obtaining Microparticle Dispersion 1. The obtained microparticles had a volume average particle diameter of 268 nm and a CV value of 5%.

[0082] [Preparation of Microparticle Dispersion 2] An auxiliary solution was prepared by dissolving 0.98 parts of sodium p-styrenesulfonate and 1.5 parts of sodium hydrogencarbonate in 2060 parts of ion-exchanged water. Also, 630 parts of styrene and 9 parts of acrylic acid were mixed to obtain a monomer mixture liquid 1. Further, 101 parts of styrene, 2 parts of acrylic acid, and 43 parts of diacetone acrylamide were mixed to obtain a monomer mixture liquid 2. The auxiliary agent solution was charged into a reaction vessel equipped with a stirrer, a heating / cooling device, a nitrogen introducing device, and a raw material / auxiliary agent charging device, and the internal temperature was raised to 77°C. Next, a polymerization initiator solution prepared by dissolving 4.3 parts of ammonium persulfate in 10 parts of ion-exchanged water was added to the reaction vessel, and 5 minutes later, the monomer mixture 1 was successively added dropwise over 150 minutes. After the dropwise addition of the monomer mixture 1 was completed, the monomer mixture 2 was successively added dropwise over 30 minutes. After the dropwise addition of the monomer mixed solution 2 was completed, stirring was continued at 77° C. for 90 minutes, and then the internal temperature was raised to 90° C. Thereafter, stirring at 90° C. was maintained for 3 hours. After cooling the internal temperature to 20°C, the polymerization reaction product was filtered through nonwoven gauze (product name "Cross Gauze No. 2", manufactured by Osaki Medical Co., Ltd.) to obtain a dispersion of microparticles. The pH of the dispersion was adjusted to 7.0 by adding 10 wt% ammonia water. Furthermore, ion-exchanged water was appropriately added to adjust the solid concentration to 29.0%, thereby obtaining microparticle dispersion 2. The resulting microparticles had a volume average particle size of 252 nm.

[0083] Example 1 A dispersion with a solids concentration of 27% was prepared by mixing 18.6 parts of Microparticle Dispersion 1, 0.067 parts of an aqueous solution containing 4% by weight of ionic PVA as a water-soluble resin, and 1.32 parts of ion-exchanged water. The dispersion was applied to a plasma-treated acrylic film (Mitsubishi Chemical Corporation, ACRYPLEN SBL902 (black), 75 μm thick) using a wire bar (OSG Corporation, OSP-25) at 15 mm / s and dried at 25 °C for 10 minutes to obtain a laminate. Next, to fix the microparticle layer on the resulting laminate, Silicone Elastomer 1 was applied at 5 mm / s using a film applicator with a film thickness adjustment function (Allgood Corporation) set to a wet film thickness of 100 μm. The curing reaction was carried out by heating at 85 °C for 30 minutes to obtain a laminate. The resulting laminate was then stretched using a universal testing machine (Shimadzu Corporation: Autograph AGX-5KNNVD). This created adjacent first and second regions (stretched and unstretched regions). A green color was observed in the first region, with a reflectance peak wavelength of 520 nm. A red color was observed in the second region, with a reflectance peak wavelength of 626 nm. The cross-sectional observation results of the first region are shown in Figure 3, and the cross-sectional observation results of the second region are shown in Figure 4. It was confirmed that the shapes of the microparticles that make up the colloidal crystal layer differed between the first and second regions. The cross-sectional photographs of Figures 3 and 4 were taken using the TEM at a magnification of 10,000. The photographs of Figures 5, 6, 7, and 8 described below were also taken in the same manner.

[0084] Example 2 A 27% solids dispersion was prepared by mixing 18.0 parts of microparticle dispersion 2, 1.37 parts of an aqueous solution containing 10% by weight of adipic acid dihydrazide, 0.066 parts of an aqueous solution containing 4% by weight of ionic PVA as a water-soluble resin, and 0.53 parts of ion-exchanged water. The dispersion was applied to a plasma-treated black polyester film (Mitsubishi Chemical Corporation, Diafoil B100 type, thickness: 50 μm, transmittance density: 3.2) using a wire bar (OSG, OSP-25) at a speed of 15 mm / sec and dried at 25 °C for 10 minutes to obtain a laminate. Next, to fix the microparticle layer on the resulting laminate, silicone elastomer 2 was applied to the laminate using a wire bar (OSG, OSP-6) at a speed of 15 mm / sec and cured by heating at 130 °C for 2 minutes to obtain a laminate. Next, a portion of the obtained laminate was subjected to a heat press process using a "small heat press" manufactured by Taiyo Co., Ltd. This created adjacent first regions (compressed areas) and second regions (uncompressed areas). A green color was observed in the first region, with a reflectance peak wavelength of 558 nm. An orange color was observed in the second region, with a reflectance peak wavelength of 584 nm.

[0085] Example 3 A dispersion with a solids concentration of 27% was prepared by mixing 18.0 parts of microparticle dispersion 2, 1.37 parts of an aqueous solution containing 10% by weight of adipic acid dihydrazide, 0.066 parts of an aqueous solution containing 4% by weight of ionic PVA as a water-soluble resin, and 0.53 parts of ion-exchanged water. The dispersion was applied to a plasma-treated polyester film (Toray Industries, Inc., Lumirror (black), 100 μm thick) using a wire bar (OSG, OSP-25) at 15 mm / s and dried at 25 °C for 10 minutes to obtain a laminate. Next, to fix the microparticle layer on the resulting laminate, silicone elastomer 1 was applied at 5 mm / s using a film applicator with a film thickness adjustment function (Allgood Co., Ltd.) set to a wet film thickness of 100 μm. The curing reaction was carried out by heating at 85 °C for 30 minutes to obtain a laminate. Next, a portion of the obtained laminate was clamped in a vice and heated at 200°C for 30 minutes to perform a compression treatment. This created adjacent first regions (compressed areas) and second regions (uncompressed areas). A green color was observed in the first region, with a reflectance peak wavelength of 520 nm. An orange color was observed in the second region, with a reflectance peak wavelength of 594 nm. The cross-sectional observation results of the first region are shown in Figure 5, and the cross-sectional observation results of the second region are shown in Figure 6. It was confirmed that the shapes of the microparticles constituting the colloidal crystal layer were different in the first and second regions. The cross-sectional observation was performed in the same manner as in Example 1.

[0086] (Comparative Example 1) The silica particle aqueous dispersion was applied to a plasma-treated acrylic film at a rate of 15 mm / sec using a wire bar and dried at 25°C for 10 minutes to obtain a laminate containing a colloidal crystal layer made of silica particles. Next, to fix the fine particle layer on the obtained laminate, silicone elastomer 1 was applied to a film thickness adjustment function film with a wet film thickness of 100 μm. The coating was applied at 5 mm / sec using a film applicator, and the coating was heated at 85°C for 30 minutes to cause a curing reaction, yielding a laminate. The resulting laminate was then stretched using a universal testing machine. This created adjacent first and second regions (stretched and non-stretched regions). No coloring was observed in the first region. Orange coloring was observed in the second region, with a reflectance peak wavelength of 576 nm. The cross-sectional observation results for the first region are shown in Figure 7, and those for the second region are shown in Figure 8. It was confirmed that the shapes of the microparticles constituting the colloidal crystal layer were identical in the first and second regions. Furthermore, the regular arrangement of the microparticles was impaired in the first region. The cross-sectional observation was performed in the same manner as in Example 1.

[0087] (result) The laminates of Examples 1, 2, and 3 were formed by stretching or compression to form adjacent first and second regions, with the first region having a first reflectance peak wavelength and the second region having a second reflectance peak wavelength, which were different from each other. As a result, the laminates exhibited excellent design properties. Cross-sectional observations of Examples 1 (FIGS. 3 and 4) and Example 3 (FIGS. 5 and 6) revealed that the particle shapes of the adjacent first and second regions were different. The laminate of Comparative Example 1, whose colloidal crystal layer was made of inorganic silica particles, lost its color upon stretching. Cross-sectional observations of Figures 7 and 8 revealed that the regular arrangement of the particles was not maintained during stretching. [Explanation of symbols]

[0088] 11 Laminate 11a Partially stretched laminate 11b Partially compressed laminate 12 Base material 13a Elongated particles 13b Compressed particles 14 Protective layer A,A' First region B. Second Area

Claims

1. A laminate having a substrate, a colloidal crystal layer, and a protective layer, the laminate has a first region and a second region adjacent to each other, the first region having a first reflectance peak wavelength for incident light, and the second region having a second reflectance peak wavelength for the incident light; the first reflectance peak wavelength and the second reflectance peak wavelength are different wavelengths, the first region has a first colloidal crystal layer containing first fine particles, and the second region has a second colloidal crystal layer containing second fine particles; The laminate, wherein the first fine particles and the second fine particles have different shapes.

2. The laminate of claim 1 , wherein the first particulates have the same composition as the second particulates.

3. The laminate according to claim 1 , wherein the first fine particles comprise a polymer containing structural units derived from styrene and structural units derived from acrylic acid.

4. 2. The laminate according to claim 1, wherein the first colloidal crystal layer and the second colloidal crystal layer are successively formed layers.

5. The method includes the steps of forming a laminate including a colloidal crystal layer and a protective layer on a substrate, and processing the laminate to form a first region and a second region, the first region has a first reflectance peak wavelength for incident light; the second region has a second reflectance peak wavelength for the incident light; the first reflectance peak wavelength and the second reflectance peak wavelength are different wavelengths, the first region has a first colloidal crystal layer containing first microparticles; the second region has a second colloidal crystal layer containing second microparticles; The method for manufacturing a laminate, wherein the first fine particles and the second fine particles have different shapes.

6. The method for producing a laminate according to claim 5 , wherein the processing treatment is a process of stretching a part of the laminate.

7. The method for producing a laminate according to claim 5 , wherein the processing treatment is a process of compressing a part of the laminate.

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