Laminated film and method for manufacturing the same

Abstract

To provide a laminated film that offers control over the structural coloration and reflectance of a curable resin layer and a method for producing the same.SOLUTION: A laminated film includes a curable resin layer on at least one side of a substrate film. The curable resin layer is a cured layer of a curable resin composition containing fine particles (A) and fine particles (B), satisfying the following (1)-(2): (1) the fine particles (A) are polymeric fine particles composed of polystyrenes or poly(meth)acrylates; and (2) the fine particles (B) are conductive fine particles.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a laminated film and a method for producing the same. [Background technology]

[0002] Laminated films, in which a functional layer is provided on at least one side of a base film, are used in a variety of fields, including industrial materials, optical materials, electronic component materials, and battery packaging materials. As the base film for laminated films, polyethylene terephthalate (PET) film, particularly biaxially oriented PET film, is widely used because of its excellent transparency, mechanical strength, heat resistance, and flexibility.

[0003] When light is incident on a colloidal crystal in which monodisperse nanoparticles are arranged three-dimensionally, diffraction interference causes light of a specific wavelength to be reflected (Bragg reflection), depending on the periodic structure of the crystal. When this reflected wavelength falls in the visible light region, it can be seen as structural coloration, or structural color. In recent years, research on such colloidal crystals has been actively conducted (Patent Documents 1-3), and applications in various fields, such as optical elements and optically functional materials, are expected. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 5003268 [Patent Document 2] International Publication No. 2008 / 120529 [Patent Document 3] Japanese Patent Publication No. 2014-189719 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, conventional technologies only focus on the expression of structural color, and there is no description or suggestion regarding the addition of other functions.

[0006] Therefore, the present invention aims to address the above-mentioned problems by providing a laminated film with adjustable reflectivity as a structural coloration property and other functional properties, as well as a method for manufacturing the same. [Means for solving the problem]

[0007] As a result of diligent research, the inventors of the present invention have found that the above problems can be solved by using a laminated film equipped with a cured resin layer of a specific configuration, and have completed the present invention described below. In other words, the present invention provides the following [1] to

[14] .

[0008] [1] A laminated film comprising a cured resin layer on at least one side of a base film, The cured resin layer is a cured product layer of a cured resin composition containing fine particles (A) and fine particles (B). A laminated film that satisfies the following conditions (1) and (2). (1) The fine particles (A) are polymer fine particles consisting of either polystyrenes or poly(meth)acrylic acid esters. (2) The fine particles (B) are conductive fine particles. [2] The laminated film according to [1] above, wherein the conductive fine particles are (b1) a polymer obtained by doping a compound consisting of thiophene or a thiophene derivative with another anionic compound, or (b2) a polymer having an anionic group in a compound consisting of thiophene or a thiophene derivative and being self-doped. [3] The laminated film according to either [1] or [2] above, wherein the cured resin layer further comprises (C) a water-soluble resin. [4] A laminated film according to any one of [1] to [3] above, wherein the content of fine particles (B) is 0.1 to 10 parts by mass per 100 parts by mass of fine particles (A). [5] The laminated film according to any one of [1] to [4] above, wherein the base film is a polyester film. [6] The laminated film according to [5] above, wherein the polyester film is a colorless transparent polyester film. [7] The laminated film according to [5] above, wherein the polyester film is a black polyester film. [8] The laminated film according to any one of [1] to [7] above, wherein the thickness of the cured resin layer is 1 μm to 10 μm. [9] The laminated film according to any one of [1] to [8] above, wherein the reflectance of light with a wavelength of 550 nm on the surface of the cured resin layer is 14% or less.

[10] A method for producing the laminated film according to any one of [1] to [9] above, comprising a heat treatment step of heating the cured resin composition applied on the base film at 25°C to 120°C for 10 seconds to 30 minutes to form the cured resin layer. [[ID=十四]]

[11] The laminated film according to any one of [1] to [9] above, which is for decoration. [[ID=十五]]

[12] The laminated film according to any one of [1] to [9] above, which is for optics. [[ID=十六]]

[13] The laminated film according to any one of [1] to [9] above, which is for a display. [[ID=十七]]

[14] The laminated film according to any one of [1] to [9] above, which is for a color filter. [[ID=十八]] [[ID=十九]]

Effect of the Invention

[0009] [[ID=二十三]] [[ID=二十四]]According to the present invention, it is possible to provide a laminated film capable of adjusting the structural colorability and reflectance of a cured resin layer having a specific structure, and a method for producing the same. [[ID=二十五]] [[ID=二十六]]

Brief Description of the Drawings

[0010] [[ID=三十]] [[ID=三十一]] [Figure 1] [[ID=三十二]]It is a schematic diagram showing a state in which the fine particles (A) are regularly arranged in the cured resin layer to exhibit structural colorability. [[ID=三十三]] [[ID=三十四]] [[ID=三十五]]

Embodiment for Carrying Out the Invention

[0011] Hereinafter, an example of an embodiment of the present invention will be described. However, the present invention is not limited to the embodiments described below.

[0012] The laminated film of the present invention is a laminated film provided with a cured resin layer on at least one side of a base film, wherein the cured resin layer is a cured product layer of a cured resin composition containing fine particles (A) and fine particles (B), and is a laminated film satisfying the following (1) to (2). (1) The fine particles (A) are polymer fine particles composed of either polystyrenes or poly(meth)acrylate esters. (2) The fine particles (B) are conductive fine particles. Hereinafter, the present invention will be described while referring to an embodiment of a laminated film in which a cured resin layer formed by curing a cured resin composition is provided on a base film.

[0013] <Laminated Film> The laminated film of the present invention (hereinafter, may be referred to as "the present laminated film") includes a base film and a cured resin layer formed on at least one surface of the base film. Hereinafter, each member will be described in more detail. First, each member constituting the laminated film will be described.

[0014] <Base Film> The base film constituting the present laminated film (hereinafter, may be referred to as "the present base film") is not particularly limited in its material as long as it is in the form of a film. For example, it may be made of paper, resin, metal, or the like. Among these, from the viewpoints of mechanical strength and flexibility, it is preferably made of resin.

[0015] Examples of resin-based base films include resin films formed by creating a film of polymers such as polyethylene, polypropylene, cycloolefin polymer (COP), polyester, polystyrene, acrylic resin, polycarbonate, polyurethane, triacetylcellulose (TAC), polyvinyl chloride, polyethersulfone, polyamide, polyimide, and polyamideimide. Furthermore, if it is possible to form a film, these materials may be mixed together (polymer blends) or compounded (polymers) of their constituent units.

[0016] Among the films exemplified above, polyester film is particularly preferred because it has excellent physical properties such as heat resistance, flatness, optical properties, and strength. The polyester film may be a single layer or a multilayer film (i.e., a laminated film) having two or more layers with different properties. Polyester film is a film whose main component resin is polyester. Furthermore, the polyester film may be an unoriented film (sheet) or an oriented film. In particular, an oriented film stretched in either a uniaxial or biaxial direction is preferred. Among these, a biaxially oriented film is more preferred from the viewpoint of balance of mechanical properties and flatness. Therefore, a biaxially oriented polyester film is even more preferred.

[0017] The polyester, which is the main component resin of the above-mentioned polyester film, may be either homopolyester or copolymerized polyester. The main component resin refers to the resin with the largest mass percentage among the resins that make up the polyester film, and it is sufficient if it accounts for 50% or more by mass, or 75% or more by mass, or 90% or more by mass, or 100% by mass of the resins that make up the polyester film.

[0018] The homopolyester described above is preferably one obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol. Examples of aromatic dicarboxylic acids include terephthalic acid and 2,6-naphthalenedicarboxylic acid, with terephthalic acid being preferred. Examples of aliphatic glycols include ethylene glycol, diethylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol, with ethylene glycol being preferred. Typical examples of homopolyesters include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT).

[0019] On the other hand, if the polyester is a copolymerized polyester, it is preferable that it is a copolymer containing 30 mol% or less of a third component. Examples of dicarboxylic acid components in copolymerized polyesters include one or more types of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, etc., and examples of glycol components include one or more types of ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, etc. Preferably, the copolymerized polyester contains terephthalic acid as the dicarboxylic acid, ethylene glycol as the glycol component, and a third component other than these. In particular, the base film is preferably made of polyethylene terephthalate, in which 60 mol% or more, preferably 80 mol% or more, are ethylene terephthalate units.

[0020] In this laminated film, particles can be incorporated into the base film primarily for the purpose of providing slipperiness and preventing scratches during each process. When incorporating particles, the type of particles to be incorporated is not particularly limited as long as they can provide slipperiness. Specific examples include inorganic particles such as silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, and titanium oxide, and organic particles such as acrylic resin, styrene resin, urea resin, phenolic resin, epoxy resin, and benzoguanamine resin. Furthermore, in the case of polyester films, precipitated particles obtained by precipitating and finely dispersing a portion of metal compounds such as catalysts during the polyester manufacturing process can also be used.

[0021] On the other hand, there are no particular restrictions on the shape of the particles used; spherical, lumpy, rod-shaped, flattened, etc., may be used. Furthermore, there are no particular restrictions on their hardness, specific gravity, color, etc. Two or more types of these particles may be used in combination as needed. Furthermore, the average particle size of the particles used is preferably 5 μm or less, and more preferably in the range of 0.1 μm to 3 μm. By using an average particle size within the above range, the film can be given an appropriate surface roughness, ensuring good slipperiness and smoothness.

[0022] The average particle size is determined by measuring the diameters of 10 or more particles using a scanning electron microscope (SEM) and taking the average value. In the case of non-spherical particles, the average of the longest and shortest diameters is used as the diameter of each particle. The same applies to the average particle size of fine particles (B) and particles in the slippery layer, as described later.

[0023] When incorporating particles, it is preferable to provide a surface layer and an intermediate layer, with the particles contained in the surface layer. In this case, it is preferable to have a multilayer structure having a particle-containing surface layer, an intermediate layer, and a particle-containing surface layer in that order.

[0024] Furthermore, the particle content in the base film is preferably 5% by mass or less, more preferably in the range of 0.0003% by mass to 3% by mass. By keeping the particle content within the above range, it is easier to impart slipperiness to the base film while ensuring its transparency. However, the base film does not need to contain substantially any particles. In this specification, "substantially particle-free" means intentionally free of particles, and specifically refers to a particle content (particle mass concentration) of 200 ppm or less, more preferably 150 ppm or less, relative to the component or layer (in this case, the base film). Similar terms shown below have the same meaning. If the base film contains virtually no particles, or only a small amount, the transparency of the base film increases, resulting in a film with a good appearance, and the surface of the cured resin layer tends to become smoother. On the other hand, the slipperiness of the laminated film may be insufficient. In such cases, the slipperiness may be improved by incorporating particles into the cured resin layer, or by providing an easy-slip layer containing particles, as described later.

[0025] There are no particular restrictions on the color of the polyester film that constitutes this base film, but for optical applications where transparency is particularly required, a colorless and transparent polyester film is preferable. For decorative applications where appearance is important, a black polyester film is preferable.

[0026] The thickness of the base film is preferably 9 μm to 350 μm, more preferably 12 μm to 250 μm, and particularly 25 μm to 125 μm. When the base film is within the above range, it can be suitably used in various fields such as industrial materials, optical components, cosmetics, packaging materials, automotive interiors, and decorative applications.

[0027] When the base film has a laminated structure having two or more layers, a three-layer structure consisting of a base layer A, a surface layer B, and a surface layer C (B / A / C) or a three-layer structure consisting of a base layer A and a surface layer B (B / A / B) is preferred. When the base film has a laminated structure having two or more layers, the main component resin constituting each layer is preferably polyester, as described above.

[0028] <Cured resin layer> The cured resin layer of this laminated film (hereinafter sometimes referred to as "this cured resin layer") is formed by curing a cured resin composition and is provided on a base film. The cured resin layer may be provided on only one side of the base film, or on both sides. This cured resin layer has the characteristic of having structural coloration properties and the ability to adjust reflectivity. The curing resin composition contains components that become polymers upon polymerization, and specifically, it may contain either photopolymerizable compounds or thermopolymerizable compounds.

[0029] The curing resin composition must contain fine particles (A) having structural coloration properties and fine particles (B) having conductivity. In this invention, it is presumed that the expression of structural color is made possible by the formation of a structure in which fine particles (A) are arranged with a certain degree of regularity. The fine particles (B) are characterized by their ability to act as a so-called "structural scattering agent," disrupting the aforementioned arranged structure.

[0030] <Fine particles (A)> Fine particles (A) represent fine particles made of a general polymer. Common polymers include, for example, polyamides, polyimides, low-density polyethylene, high-density polyethylene, poly(meth)acrylic acid esters, polystyrenes such as polystyrene and its derivatives, polyvinyl chloride, phenolic resins, and polycarbonates.

[0031] Among these, poly(meth)acrylic acid esters and polystyrenes are necessary because the raw materials are readily available and it is easy to produce fine particles with uniform particle size. Of these, polystyrenes are preferred because they yield polymers with a high refractive index. Polymers with a high refractive index are preferred because they increase the refractive index difference between the inside and outside of the particles, improving structural coloration. The fine particles (A) may be non-crosslinked polymers or crosslinked polymers.

[0032] Regarding the method for producing fine particles (A), for example, one method involves obtaining a polymer of an appropriate size by bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization, etc., pulverizing it to obtain a fine powder, and then standardizing the particle size by operations such as sieving. Another method involves directly obtaining fine particles (A) with a uniform particle size by soap-free emulsion polymerization. Among these methods, the soap-free emulsion polymerization method is preferred due to its superior productivity.

[0033] In the present invention, the fine particles (A) may be of one type only, or two or more types may be mixed and used.

[0034] [Poly(meth)acrylic acid esters] In this invention, poly(meth)acrylic acid esters refer to polymers mainly composed of (meth)acrylic acid ester units. Here, "main component" means that the content of (meth)acrylic acid ester units relative to the entire polymer is 50% by mass or more, and more specifically, 60% by mass or more. "(meth)acrylic acid" refers to either or both of "acrylic acid" and "methacrylic acid".

[0035] Examples of (meth)acrylic acid esters that serve as raw materials for (meth)acrylic acid ester units include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate.

[0036] Poly(meth)acrylic acid esters may be either random copolymers or block copolymers, but are generally random copolymers. Poly(meth)acrylic acid esters may be copolymerized with any monomer in addition to the (meth)acrylic acid esters described above.

[0037] Examples of arbitrary monomers include styrenes such as styrene and methylstyrene; metal salts such as sodium salt of styrene sulfonic acid; acidic monomers such as acrylic acid and methacrylic acid; and acrylamides such as acrylamide and N-propylacrylamide. Among these, metal salts such as sodium salts of styrene sulfonic acid are preferred because they allow for good control of particle size. Furthermore, when introducing a crosslinked structure to poly(meth)acrylic acid esters, known polyfunctional monomers can be copolymerized.

[0038] [Polystyrenes] In this invention, polystyrenes refer to polymers whose main component is styrene units. Here, "main component" means that the content of styrene units relative to the entire polymer is 50% by mass or more, and more specifically, 60% by mass or more. Polystyrenes can be either random copolymers or block copolymers, but they are generally random copolymers. Polystyrenes may be copolymerized with any monomer other than styrene.

[0039] Examples of arbitrary monomers include styrenes other than styrene, such as methylstyrene and chlorostyrene; metal salts such as sodium salt of styrene sulfonic 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 and N-propylacrylamide. Among these, metal salts such as sodium salts of styrene sulfonic acid are preferred because they allow for good control of particle size. Furthermore, when introducing a crosslinked structure to polystyrenes, known polyfunctional monomers can be copolymerized.

[0040] Polystyrenes preferably contain 80.0% to 99.75% by mass of styrene units. A styrene unit content within this range is preferable because it increases the refractive index of the particles and improves structural color development. A styrene unit content of 90.0% by mass or more is more preferable, and 99.4% by mass or less is even more preferable.

[0041] The number-average particle size of the fine particles (A) is preferably 50 nm to 450 nm, particularly 100 nm to 400 nm, and especially 150 nm to 300 nm, from the viewpoint of improving structural color development. The number-average particle size of the fine particles (A) is the value measured by the method described in the Examples section below.

[0042] <Fine particles (B)> The fine particles (B) must be conductive. The fine particles (B) are preferably (b1) polymers doped with other anionic compounds in a compound consisting of thiophene or a thiophene derivative, or (b2) polymers that have anionic groups in a compound consisting of thiophene or a thiophene derivative and are self-doped. These materials exhibit excellent conductivity and are therefore preferred. In the present invention, the fine particles (B) may be of one type only, or two or more types may be used in combination. For example, polymer (b1) and polymer (b2) may be used in combination.

[0043] Examples of fine particles (B) include those obtained by polymerizing a compound represented by formula (1) or formula (2) in the presence of a polyanion.

[0044] [ka]

[0045] In the above equation (1), R 1 and R 2 Each of these independently represents a hydrogen atom, or an aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic hydrocarbon group, etc., with 1 to 20 carbon atoms.

[0046] [ka]

[0047] In equation (2) above, n represents an integer from 1 to 4.

[0048] Examples of polyanions used during polymerization include poly(meth)acrylic acid, polymaleic acid, polystyrene sulfonic acid, and polyvinyl sulfonic acid. A method for producing such polymers can be employed, for example, the method described in Japanese Patent Publication No. 7-90060.

[0049] In the present invention, a compound represented by formula (2) above in which n is 2 and polystyrene sulfonic acid is used as the polyanion is preferably used.

[0050] Furthermore, if these polyanions are acidic, some or all of them may be neutralized. Ammonia, organic amines, and alkali metal hydroxides are preferred bases for neutralization.

[0051] The average particle size of the fine particles (B) is preferably 10 nm to 150 nm, particularly 20 nm to 150 nm, and especially 40 nm to 100 nm, from the viewpoint of not disrupting the arrangement of the fine particles (A).

[0052] <(C) Water-soluble resin> The cured resin layer preferably contains (C) a water-soluble resin. A water-soluble resin is a polymer compound that dissolves in water or at least disperses in water. (C) As for water-soluble resins, those that have ionic groups such as sulfonyl groups and carboxyl groups, or water-soluble substituents such as hydroxyl groups in the molecule, and that dissolve in water are preferred. (C) The water-soluble resin enables the formation of a uniform coating film as the main cured resin layer.

[0053] Water-soluble resins include nonionic water-soluble resins and ionic water-soluble resins. Examples of nonionic water-soluble resins include water-soluble polyacrylamide, water-soluble acrylic resins, nonionic polyvinyl alcohol-based resins, polyvinylpyrrolidone, polyethylene oxide, polyvinyl acetate; and natural polymer compounds such as starch, gelatin, and casein. Examples of ionic water-soluble resins include water-soluble polyester resins, polyacrylic acid, ionic polyvinyl alcohol-based resins, and carboxymethylcellulose.

[0054] Among these, it is preferable to use nonionic polyvinyl alcohol-based resins and / or ionic polyvinyl alcohol-based resins due to the high hydrolysis resistance of the polymer main chain. Furthermore, among water-soluble resins, ionic water-soluble resins are preferred because they improve ionic strength. In the present invention, (C) water-soluble resin may be used alone or as a mixture of two or more types.

[0055] [Ionic water-soluble resin] Ionic water-soluble resins are water-soluble resins that have anionic or cationic parts, and are specifically as described above. Among ionic water-soluble resins, ionic polyvinyl alcohol-based resins are preferred because they have excellent solvent resistance.

[0056] [Ionic polyvinyl alcohol-based resin] Ionic polyvinyl alcohol resins are polyvinyl alcohol resins that contain ionic groups such as sulfonyl groups or their salts, carboxyl groups or their salts, or quaternary ammonium salts in their molecular chains.

[0057] Examples of ionic polyvinyl alcohol-based resins include polyvinyl alcohol-based resins containing a sodium salt of a sulfonyl group in the molecular chain, and polyvinyl alcohol-based resins containing a sodium salt of a carboxyl group in the molecular chain. Among these, polyvinyl alcohol-based resins containing a sodium salt of a sulfonyl group are preferred because the salt dissociates easily.

[0058] Examples of commercially available ionic polyvinyl alcohol-based resins include Gosenex (manufactured by Mitsubishi Chemical Corporation, a specially modified polyvinyl alcohol-based resin).

[0059] <(D) Water solvent> The curing resin composition used to form this curing resin layer (hereinafter sometimes referred to as "this curing resin composition") may be diluted with (D) an aqueous solvent to form a coating solution. This curing resin composition is preferably applied to the substrate film as a liquid coating solution, dried, and cured to form the curing resin layer. Each component constituting this cured resin composition can be dissolved or dispersed in (D) aqueous solvent. In the present invention, it is preferable that the cured resin composition is substantially free of organic solvents. "Substantially free of organic solvents" means that, in addition to water, small amounts of organic solvents that could not be completely removed during the manufacturing process of the fine particles (A) may be mixed in, as long as it does not impair the spirit of the present invention. Specifically, the amount should be 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less, relative to the total mass of water. Specific examples of organic solvents include, for example, alcohol-based solvents such as methanol, ethanol, propanol, isopropanol, and butanol.

[0060] (D) There are no particular restrictions on the amount of aqueous solvent used, and it is determined as appropriate considering the coatability of the prepared cured resin composition, the viscosity and surface tension of the liquid, the compatibility of the solids, etc. The cured resin composition is preferably prepared using (D) aqueous solvent as a coating solution with a solids concentration of 5% to 80% by mass, more preferably 10% to 70% by mass, and particularly preferably 15% to 60% by mass. Furthermore, in a cured resin composition, "solid content" refers to the components excluding the volatile solvent, and includes not only solid components but also semi-solid and viscous liquid substances.

[0061] <(E) Other ingredients> This curing resin composition may contain various additives as needed, within the limits that do not impair the spirit of the present invention. Examples of additives include antioxidants, antistatic agents, leveling agents, dispersants, thixotropic agents (thickeners), and defoaming agents. Only one of these may be included, or two or more may be included.

[0062] <Content of each ingredient> From the viewpoint of obtaining good structural coloration, the content of fine particles (B) in the cured resin layer and the cured resin composition is preferably in the range of 0.1 to 10 parts by mass, more preferably in the range of 0.1 to 5 parts by mass, and even more preferably in the range of 0.1 to 3 parts by mass, per 100 parts by mass of fine particles (A).

[0063] If the cured resin layer and the cured resin composition contain (C) a water-soluble resin, the content of (C) the water-soluble resin is preferably in the range of 0.001 parts by mass to 0.4 parts by mass, more preferably in the range of 0.005 parts by mass to 0.4 parts by mass, and even more preferably in the range of 0.05 parts by mass to 0.4 parts by mass, per 100 parts by mass of fine particles (A) in the cured resin layer and the cured resin composition, from the viewpoint of structural color development. Furthermore, the content of fine particles (A) in the solid content of the cured resin layer and the cured resin composition is preferably in the range of 5% to 60% by mass, particularly 10% to 40% by mass, and especially 20% to 40% by mass, from the viewpoint of structural color development.

[0064] <Thickness of the hardened resin layer> The thickness of the cured resin layer is typically in the range of 1 μm to 10 μm, preferably 2 μm to 9 μm, and more preferably 3 μm to 8 μm. By setting the thickness of the cured resin layer within the above range, the desired structural color is more easily achieved. Here, the thickness of the cured resin layer is the thickness after applying and heating / drying the cured resin composition in the laminated film manufacturing method described later.

[0065] <Method for forming a hardened resin layer> As described above, this cured resin layer can be obtained by applying this cured resin composition to the surface of a base film, drying it to form a coating layer, and then curing the coating layer. Conventional coating methods such as air doctor coating, blade coating, rod coating, bar coating, knife coating, squeeze coating, impregnation coating, reverse roll coating, transfer roll coating, gravure coating, kiss roll coating, cast coating, spray coating, curtain coating, calender coating, and extrusion coating can be used to apply this cured resin composition. The drying conditions are not particularly limited and may be carried out at or near room temperature, or by heating. Considering the heat resistance of the fine particles (A), melting of the fine particles (A) tends to begin above 120°C. Therefore, a range of 25°C to 120°C is preferable, more preferably 25°C to 110°C, and within that range, 30°C to 100°C is particularly good. Furthermore, the drying time is not particularly limited as long as the (D) aqueous solvent can evaporate sufficiently, and is, for example, 10 seconds to 30 minutes, preferably 15 seconds to 10 minutes. In other words, the laminated film is preferably manufactured according to a method for manufacturing a laminated film of the present invention, which includes a heat treatment step of heating the cured resin composition applied to the base film at 25°C to 120°C for 10 seconds to 30 minutes to form the cured resin layer.

[0066] The curing method for this curable resin composition can be appropriately selected according to the curing mechanism of the curable resin composition. If the curable resin composition is a thermosetting resin composition, it can be cured by heating. If it is a photocurable resin composition, it can be cured by irradiation with active energy rays.

[0067] Active energy rays that can be used to cure curable resin compositions include ultraviolet rays, electron beams, X-rays, infrared rays, and visible light. Of these active energy rays, ultraviolet rays and electron beams are preferred from the viewpoint of curability and prevention of resin degradation. From the viewpoints of molding time and productivity, and preventing thermal shrinkage and thermal degradation of each member due to heating, among these, curing by energy ray irradiation is preferable. The energy ray irradiation may be performed from any surface side, from the substrate film side, or from the opposite side of the substrate film. When manufacturing a laminated film, when curing a curable resin composition by ultraviolet irradiation, various ultraviolet irradiation devices can be used, and as the light source, a xenon lamp, a high-pressure mercury lamp, a metal halide lamp, an LED-UV lamp, etc. can be used. The irradiation amount of ultraviolet rays (unit: mJ / cm 2 ) is usually 50 mJ / cm 2 ~3,000 mJ / cm 2 , and from the viewpoints of the curability of the curable resin composition, the flexibility of the cured product (cured film), etc., it is preferably 100 mJ / cm 2 ~1,000 mJ / cm 2 , and from the viewpoint of the flatness of the laminated film, it is more preferably 100 mJ / cm 2 ~500 mJ / cm 2 and is appropriately determined within this range.

[0068] Also, when manufacturing a laminated film, when curing a curable resin composition by electron beam irradiation, various electron beam irradiation devices can be used. The irradiation amount of electron beams (Mrad) is usually 0.5 Mrad~20 Mrad, and from the viewpoints of the curability of the curable resin composition, the flexibility of the cured product, preventing damage to the substrate, etc., it is preferably appropriately determined within the range of 1 Mrad~15 Mrad.

[0069] <Easy adhesion layer> This laminated film may have an easy adhesion layer on the surface of the substrate film. The easy adhesion layer is preferably provided on one surface of the substrate film on which the present curable resin layer is provided, and the above-described curable resin layer is preferably formed on the surface of the easy adhesion layer. By providing an easy adhesion layer, it may become easier to adhere the curable resin layer to the substrate film. The easy adhesion layer is formed from an easy adhesion layer composition containing a binder resin and a crosslinking agent.

[0070] Examples of binder resins include polyester resins, acrylic resins, urethane resins, polyvinyl resins such as polyvinyl alcohol, polyalkylene glycols, polyalkyleneimines, methylcellulose, hydroxycellulose, and starches. Among these, polyester resins, acrylic resins, and urethane resins are preferred, and polyester resins and acrylic resins are more preferred, from the viewpoint of improving adhesion with the cured resin layer. These binder resins may be used individually or in combination of two or more. In the easy-adhesion layer composition, the binder resin content is, for example, 20% to 90% by mass, preferably 30% to 80% by mass, based on solid content.

[0071] Various known crosslinking agents can be used, such as oxazoline compounds, melamine compounds, epoxy compounds, isocyanate compounds, carbodiimide compounds, and silane coupling compounds. The oxazoline compound may be an acrylic polymer having an oxazoline group, for example. Among these, melamine compounds, oxazoline compounds, and epoxy compounds are preferred. These crosslinking agents may be used individually or in combination of two or more. The crosslinking agent content in the easy-adhesion layer composition is, for example, 5% to 50% by mass, preferably 10% to 40% by mass, based on solid content.

[0072] The easy-adhesion layer composition may contain particles to improve blocking resistance and slipperiness. The particles described later in the section on the easy-slip layer can be used as appropriate. However, it is preferable that the easy-adhesion layer composition (i.e., the easy-adhesion layer) is substantially free of particles. By substantially omitting particles, the smoothness of the cured resin layer surface can be improved. Furthermore, the easy-adhesion layer composition may contain components to promote crosslinking, such as crosslinking catalysts. In addition, it is possible to use defoaming agents, coating properties improvers, thickeners, organic lubricants, antistatic agents, UV absorbers, antioxidants, foaming agents, dyes, pigments, etc. in combination.

[0073] The easy-adhesion layer composition is generally preferably diluted with water, an organic solvent, or a mixture thereof. The easy-adhesion layer is formed by coating the surface of a substrate film with the diluted easy-adhesion layer composition as a coating solution and then drying it. The coating can be carried out by conventionally known methods.

[0074] The thickness of the easy-adhesion layer is typically in the range of 0.003 μm to 1 μm, preferably 0.005 μm to 0.6 μm, and more preferably 0.01 μm to 0.4 μm. A thickness of 0.003 μm or more ensures sufficient adhesion. Conversely, a thickness of 1 μm or less reduces the likelihood of deterioration of appearance or blocking.

[0075] <Easy layer> The laminated film may have a slip-free layer. The slip-free layer is preferably provided on the side of the base film opposite to the side on which the cured resin layer is provided. The slip-free layer is preferably provided on the surface of the base film. The presence of the slip-free layer improves the slipperiness of the laminated film. Therefore, as described above, even if the smoothness of the side of the laminated film on which the cured resin layer is provided is improved, the roll winding and handling properties of the laminated film remain good.

[0076] The smooth layer is formed from a smooth layer composition, for example, a binder resin, a crosslinking agent, and particles. The compounds that can be used as binder resins and crosslinking agents are as described in the section on binder resins and crosslinking agents used in the above-mentioned easy-to-adhere layer. Furthermore, the binder resin content in the smooth-slip layer composition is, for example, 20% to 90% by mass, preferably 30% to 80% by mass, based on solid content. The crosslinking agent content in the smooth-slip layer composition is, for example, 5% to 50% by mass, preferably 10% to 40% by mass, based on solid content.

[0077] Specific examples of particles used in the slippery layer include silica, alumina, kaolin, calcium carbonate, and organic polymer particles. Among these, silica is preferred from the viewpoint of transparency. The average particle size is preferably in the range of 0.005 μm to 1.0 μm, more preferably 0.01 μm to 0.8 μm, and even more preferably 0.01 μm to 0.6 μm, from the viewpoint of improving slipperiness without impairing the surface smoothness of the polyester film. The particle content in the slippery layer composition is, for example, 1% to 20% by mass, preferably 3% to 15% by mass, based on solid content. The particles used in the slippery layer may be used alone or in combination of two or more types.

[0078] The slippery layer composition is generally preferably diluted with water, an organic solvent, or a mixture thereof. The slippery layer is formed by coating the surface of a substrate film with the diluted slippery layer composition as a coating solution and then drying it. The coating can be carried out by conventionally known methods.

[0079] The thickness of the slippery layer is typically in the range of 0.003 μm to 1 μm, preferably 0.005 μm to 0.6 μm, and more preferably 0.01 μm to 0.4 μm. A thickness of 0.003 μm or more allows for sufficient retention of particles contained in the slippery layer, thereby providing slipperiness. A thickness of 1 μm or less reduces the likelihood of deterioration of appearance and blocking.

[0080] <Coating> The surface of this base film can be coated as needed, and the coating may form the easy-adhesion layer and the easy-slip layer described above. The coating can be performed in-line, off-line, or a combination of both, but it is preferable to perform it in-line. When performing the coating in-line, it is preferable to apply the coating to the base film in the base film manufacturing line. For example, if the base film is a biaxially oriented film, for example, after the longitudinal stretching is completed, a coating solution for forming at least one of the easy-adhesion layer and the easy-slip layer may be applied, and then the coating solution may be dried and cured in the subsequent manufacturing process of the base film.

[0081] <Physical properties of laminated films> (Structural color development) The fine particles (A) used in this invention have structural coloration properties. Structural coloration means that, as shown in Figure 1, structural color is exhibited when fine particles of uniform size are arranged in a regular manner. Structural coloration refers to an angle-dependent coloration phenomenon where the color appears to change depending on the viewing angle, due to optical and physical phenomena such as interference and scattering occurring depending on the wavelength of light, because the particles have a crystalline structure in which they are arranged in a regular manner.

[0082] Since structural coloration is due to the properties of light, it occurs not only in the visible light region but also in the ultraviolet and infrared regions. To produce structural color in the ultraviolet region, it is sufficient to use nanoparticles with a small number-average particle size, for example, 50 nm to 100 nm. To produce structural color in the infrared region, it is sufficient to use nanoparticles with a large number-average particle size, for example, 100 nm to 450 nm. In this invention, from the viewpoint of utilizing structural coloration to improve the decorative properties of the film, it is preferable to exhibit structural color in the visible light region.

[0083] Here, the visible light region refers to wavelengths from 360nm to 830nm, the ultraviolet region refers to wavelengths from 200nm to 359nm, and the infrared region refers to wavelengths from 831nm to 2500nm. In this invention, for structural color development evaluation, the color tone was evaluated visually by sensory evaluation when the surface of the cured resin layer was viewed from the front and at a 45-degree angle.

[0084] (Glossiness) Visual sensory evaluation reveals that, as shown in Examples 1-3 below, the addition of fine particles (B) in this laminated film allows for adjustment of not only structural coloration but also reflectivity. On the other hand, in Comparative Example 1, shown below, since no fine particles (B) were added, the reflectance was high. Although the details of this mechanism are unknown, it is presumed that structural color is made possible by the formation of a structure in which fine particles (A) are arranged with a certain degree of regularity within the cured resin layer. It is presumed that by further adding fine particles (B), the arrangement of fine particles (A) is partially disrupted, and as a result, the reflectivity changes depending on the degree of disruption. In this invention, fine particles (B) are characterized by acting as a so-called "structural scattering agent" that disrupts the aforementioned arranged structure.

[0085] (Reflectance (550nm)) The cured resin layer preferably has a reflectance of 550nm light at its surface (hereinafter referred to as "reflectance (550nm)") of 14% or less, more preferably 10% or less, and particularly preferably 8% or less. As shown in Examples 1 to 3 below, in this laminated film, the reflectance (550 nm) tends to decrease as the amount of conductive fine particles (A) increases. This laminated film has the characteristic of providing not only structural color development but also a low gloss by keeping the reflectivity low.

[0086] (Surface resistivity) The surface resistivity of this cured resin layer is not particularly limited, but for example, 1 × 10⁻⁶ 12 Ω / □ or less, preferably 1 × 10 8 It is less than or equal to Ω / □. There is no specific lower limit for surface resistivity, but considering the cost of antistatic agents, it is 1 × 10⁻⁶ 4 It is preferable to have a ratio of Ω / □ or greater. The lower the surface resistivity of the cured resin layer, the better the antistatic properties. For example, after applying a functional layer such as an adhesive layer on the cured resin layer, peeling can suppress peeling charge and prevent the adhesion of foreign matter. The surface resistivity of the cured resin layer is measured by the method described in the Examples section below.

[0087] <Application> The laminated film of the present invention can be used in a variety of applications, including industrial materials, optical applications, and packaging materials, but it is preferably used for optical applications such as various displays, optical filters, lenses, mirrors, and window glass. Furthermore, laminated films may be used for decorative purposes such as decorative sheets. In this invention, the surface reflectivity of the cured resin layer can be adjusted, making it possible to achieve, for example, a matte finish. Therefore, in addition to the structural coloration of the laminated film, the reflectivity can be adjusted, allowing for visual adjustment of glossiness, resulting in a more advanced decorative capability and increasing the freedom of film design.

[0088] <Explanation of terms, etc.> In this invention, the term "film" includes "sheets," and the term "sheet" includes "film." In this invention, when "X~Y" (where X and Y are any numbers) is written, unless otherwise specified, it includes the meaning of "X or greater and Y or less," as well as "preferably greater than X" or "preferably less than Y." Furthermore, when "X or greater" (where X is any number) is written, unless otherwise specified, it includes the meaning of "preferably greater than X," and when "Y or less" (where Y is any number) is written, unless otherwise specified, it also includes the meaning of "preferably less than Y." [Examples]

[0089] Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples described below.

[0090] <Evaluation Method> The methods for measuring and evaluating various physical properties and characteristics are as follows:

[0091] (1) Intrinsic viscosity (IV) 1 g of polyester was accurately weighed, dissolved in 100 ml of a phenol / tetrachloroethane mixed solvent (50 / 50 by mass ratio), and measured at 30°C.

[0092] (2) Average particle size of particles in the base film The powder was observed using a scanning electron microscope (HITACHI, "S3400N"). The size of a single particle was measured from the obtained image data, and the average value of 10 points was used as the average particle size.

[0093] (3) Number average particle size of fine particles (A) An emulsion of fine particles (A) was applied to a substrate and dried. After drying, images of the fine particles were observed using an electron microscope at a magnification of 20,000x or higher. The diameters of at least 400 fine particles in the images were measured, and the number-average particle diameter was obtained by taking the arithmetic mean of these measurements.

[0094] (4) Thickness of the cured resin layer (after curing) The thickness of the cured resin layer was measured by cross-sectional observation using a scanning electron microscope (SEM).

[0095] (5) Structural color development The color tone of the cured resin layer surface was visually evaluated by sensory perception when viewed from the front and at a 45-degree angle.

[0096] (6) Glossiness (sensory evaluation) The degree of reflectivity when viewing the surface of the cured resin layer was evaluated visually through sensory evaluation.

[0097] (7)Reflectance (550nm) The reflectance (550 nm) of the surface of the cured resin layer was measured using a spectrophotometer (Hitachi High-Tech Corporation, U-3900H).

[0098] (8)Surface resistivity A high-resistivity resistivity meter (HIRESTA UX MCP-HT800) and measuring electrode (UR-100) manufactured by Mitsubishi Chemical Analytec Corporation were used. After conditioned the sample in a measurement atmosphere of 23°C and 50% RH for 30 minutes, measurements were taken at an applied voltage of 500V, and the value after 1 minute was defined as the surface resistivity. The upper limit of the measurable range of resistance values ​​(1 × 10⁻⁶) was used. 12 Measurement was deemed impossible if the value exceeded Ω / □.

[0099] The raw materials for the laminated films in each example and comparative example are as follows.

[0100] [Base film] <Polyester (A)> 100 parts by mass of dimethyl terephthalate, 65 parts by mass of ethylene glycol, and 0.09 parts by mass of calcium acetate monohydrate relative to the total amount of dimethyl terephthalate and ethylene glycol (165 parts by mass) were placed in a reactor. The mixture was heated and the temperature was increased while methanol was distilled off to carry out the transesterification reaction. After about 4.5 hours from the start of the reaction, the temperature was raised to 230°C, and the transesterification reaction was substantially completed. Next, 0.04 parts by mass of phosphoric acid and 0.035 parts by mass of antimony trioxide were added, and polymerization was carried out according to a conventional method. That is, the reaction temperature was gradually increased until it reached 280°C, while the pressure was gradually decreased until it reached 0.05 mmHg. After 4 hours, the reaction was completed, and the mixture was chipped according to a conventional method to obtain polyester (A). The intrinsic viscosity of polyester (A) was 0.63.

[0101] <Polyester (B)> Silica particles with an average particle size of 2 μm were added to the above polyester (A) to obtain polyester (B) containing 0.2% by mass of silica particles. The intrinsic viscosity of polyester (B) was 0.65.

[0102] [Cured resin composition] <Fine particles (A)> A monomer mixture was prepared by mixing 98.4 parts by mass of styrene and 1.5 parts by mass of acrylic acid. On the other hand, an auxiliary solution was prepared by dissolving 0.1 parts by mass of sodium styrenesulfonate and 0.15 parts by mass of sodium bicarbonate in 16.4 parts by mass of deionized water. In a reaction vessel equipped with a stirring device, a heating and cooling device, a nitrogen introduction device, and a raw material / auxiliary agent charging device, 177.5 parts by mass of deionized water were charged, and then the auxiliary agent solution was charged while rotating at 150 rpm, and the internal temperature was raised to 80°C. Next, an initiator solution prepared by dissolving 0.42 parts by mass of ammonium persulfate in 33.7 parts by mass of deionized water was added to the reaction vessel, and after 5 minutes, the monomer mixture was added dropwise over 3 hours. After the monomer mixture was added dropwise, polymerization was carried out over 5 hours. During the polymerization reaction after the addition of the monomer mixture, deionized water was added as needed to maintain the liquid level. Subsequently, the polymerization reaction product was filtered through nonwoven gauze (Treat) to obtain an emulsion of fine particles (A). The number-average particle size of the obtained fine particles (A) was 246 nm. Next, to this emulsion, (C) ionic PVA (anionic polyvinyl alcohol-based resin (Mitsubishi Chemical Corporation, Gosenex CKS50)) was added in an amount of 0.01 parts by mass per 100 parts by mass of fine particles (A). After neutralization with ammonia water, the mixture was diluted with (D) ion-exchanged water to a solid content concentration of 28% by mass to prepare an aqueous dispersion.

[0103] <Fine particles (B)> A conductive agent consisting of polyethylenedioxythiophene and polystyrene sulfonic acid (Orgacon ICP1010, manufactured by Agfa-Gevaert) (average particle size = 42 nm) was neutralized with concentrated ammonia water to a pH of 9. This fine particle (B)-containing solution contains 1.2% by mass of non-volatile components and water as the solvent.

[0104] [Easy adhesive layer composition] An easy-to-adhere layer composition was prepared by mixing the following compounds in a ratio of X1:X2:Y1:Y2:Y3 = 60:10:10:10:10 (mass %) of solids. <Binder resin> (X1): Aqueous dispersion of a polyester resin having a condensed polycyclic structure, copolymerized with the following composition. Monomer composition: (Acid component) 2,6-Naphthalenedicarboxylic acid / 5-Sodium sulfisophthalic acid / / (Diol component) Ethylene glycol / Diethylene glycol = 92 / 8 / / 80 / 20 (mol%) (X2): Aqueous dispersion of acrylic resin polymerized with the following composition. Ethyl acrylate / n-butyl acrylate / methyl methacrylate / N-methylolacrylamide / acrylic acid = 65 / 21 / 10 / 2 / 2 (mass%) emulsified polymer (emulsifier: anionic surfactant) <Crosslinking agent> (Y1): Hexamethoxymethylolated melamine (Y2): Water-soluble polyglycerol polyglycidyl ether (Y3): Oxazoline group-containing acrylic polymer (Epocross®, oxazoline group content 4.5 mmol / g, manufactured by Nippon Shokubai Co., Ltd.)

[0105] [Example 1] A mixed raw material prepared by combining polyester (A) and (B) in proportions of 90% by mass and 10% by mass, respectively, was used as the raw material for the outermost layer (surface layer), and polyester (A) alone was used as the raw material for the intermediate layer. These materials were supplied to two extruders, each melted at 285°C, and then co-extruded onto a cooling roll set at 40°C in a layer configuration of two types and three layers (surface layer / intermediate layer / surface layer = 1 / 8 / 1 discharge volume (mass ratio)), and cooled and solidified to obtain an unstretched sheet. Next, using the difference in roll peripheral speed, the film was stretched 3.4 times in the longitudinal direction at a film temperature of 85°C. Then, the coating solution of the easy-adhesion layer composition was applied to one side of this longitudinally stretched film, guided into a tenter, stretched 4.3 times in the transverse direction at 110°C, heat-treated at 235°C, and then relaxed by 2% in the transverse direction to obtain a colorless transparent polyester film (base film) with an easy-adhesion layer and a thickness of 50 μm.

[0106] On the easily adhering layer of the polyester film described above, a cured resin composition prepared by mixing an aqueous dispersion of fine particles (A) with a liquid containing fine particles (B) in an amount of 0.1 parts by mass per 100 parts by mass of fine particles (A) was applied using a bar coat (#10) to a thickness (after drying) of 5.1 μm, and dried at 100°C for 60 seconds to form a cured resin layer. The obtained laminated film sample was evaluated as described above. The evaluation results are shown in Table 1.

[0107] [Examples 2-3, Comparative Example 1] A laminated film was obtained in the same manner as in Example 1, except that the composition of the cured resin composition and the coating thickness were changed as shown in Table 1, and the evaluation was performed in the same manner. The evaluation results are shown in Table 1.

[0108] [Table 1]

[0109] <Consideration> Examples 1-3 showed that the addition of fine particles (B) not only improved structural coloration but also allowed for adjustment of the reflectivity of the cured resin layer surface. On the other hand, in Comparative Example 1, since no fine particles (B) were added, the reflectance was high. Although the details of this mechanism are unknown, it is presumed that structural color can be produced by the formation of a structure in which fine particles (A) are arranged in a regular manner within the cured resin layer. It is presumed that the addition of fine particles (B) further disrupts the arrangement of fine particles (A), and as a result, the reflectivity changes depending on the degree of disruption. In this invention, fine particles (B) are characterized by acting as a so-called "structural scattering agent" that disrupts the aforementioned arranged structure.

Claims

1. A laminated film comprising a cured resin layer on at least one side of a base film, The cured resin layer comprises fine particles (A), fine particles (B), and (C) a water-soluble resin. The content of fine particles (B) is 0.1 to 10 parts by mass per 100 parts by mass of fine particles (A). (C) A cured layer of a cured resin composition in which the water-soluble resin content is 0.001 parts by mass to 0.4 parts by mass per 100 parts by mass of fine particles (A), A laminated film that satisfies the following conditions (1) to (2). (1) The fine particles (A) are polymer fine particles made of either polystyrene or poly(meth)acrylic acid esters. (2) The fine particles (B) are conductive fine particles, and the conductive fine particles are (b1) a polymer obtained by doping a compound consisting of thiophene or a thiophene derivative with another anionic compound, or (b2) a polymer that has an anionic group in a compound consisting of thiophene or a thiophene derivative and is self-doped.

2. The laminated film according to claim 1, wherein the base film is a polyester film.

3. The laminated film according to claim 2, wherein the polyester film is a colorless, transparent polyester film.

4. The laminated film according to claim 2, wherein the polyester film is a black polyester film.

5. The laminated film according to any one of claims 1 to 4, wherein the thickness of the cured resin layer is 1 μm to 10 μm.

6. The laminated film according to any one of claims 1 to 5, wherein the reflectance of light with a wavelength of 550 nm on the surface of the cured resin layer is 14% or less.

7. A method for manufacturing a laminated film according to any one of claims 1 to 6, A method for manufacturing a laminated film, comprising a heat treatment step of heating the cured resin composition applied on the base film at 25°C to 120°C for 10 seconds to 30 minutes to form the cured resin layer.

8. A laminated film according to any one of claims 1 to 6, for decorative purposes.

9. A laminated film according to any one of claims 1 to 6, for optical purposes.

10. A laminated film according to any one of claims 1 to 6, for use in displays.

11. A laminated film according to any one of claims 1 to 6, for use as a color filter.

Images