Laminated film

Abstract

To provide a laminate film including an optical functional layer having a light direction conversion function and an adhesive layer protecting the optical functional layer, the laminate film suppressing a functional deterioration of the optical functional layer by the adhesive layer.SOLUTION: A laminate film includes: an optical functional layer having a first principal surface and a second principal surface, with the first principal surface having an irregular structure, in which an irregularity height is 10 nm to 100 μm; a porous layer disposed on the first principal surface of the optical functional layer; and an adhesive layer disposed on a side opposite to the optical functional layer of the porous layer. The optical functional layer is a reflection type hologram film, a microlens array film or a prism film. The porous layer has a refraction index of 1.15 to 1.30.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a laminated film. [Background technology]

[0002] Decorative films are used as a means to improve the design of various products. Depending on the application, decorative films may have an optical functional layer that has a light direction conversion function (e.g., hologram, microlens array film, prism film) (e.g., Patent Documents 1 and 2). Optical functional layers that have a light direction conversion function typically have an uneven surface structure. If such an optical functional layer is placed on the outermost surface, the surface (essentially the uneven structure) may be scratched, and the function of the optical functional layer may be reduced or lost. On the other hand, even if the surface (essentially the uneven structure) of the optical functional layer is protected by, for example, an adhesive, the function of the optical functional layer may be reduced or lost due to the protective structure. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-028981 [Patent Document 2] Japanese Patent Publication No. 2020-104467 [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention was made to solve the above-mentioned conventional problems, and its main objective is to provide a laminated film having an optical functional layer having a light direction conversion function and an adhesive layer protecting the optical functional layer, wherein the deterioration of the optical functional layer's function due to the adhesive layer is suppressed. [Means for solving the problem]

[0005] A laminated film according to an embodiment of the present invention has an optical functional layer having a first main surface and a second main surface, wherein the first main surface has a concavo-convex structure, and the height of the concavities and convexities is 10 nm to 100 µm; a porous layer provided on the first main surface of the optical functional layer; and an adhesive layer provided on the opposite side of the porous layer from the optical functional layer, wherein the optical functional layer is a reflective hologram film, a microlens array film or a prism film, and the refractive index of the porous layer is 1.15 to 1.30. In one embodiment, the porous layer contains a silicon compound. In one embodiment, the porosity of the porous layer is 20% by volume to 60% by volume. In one embodiment, the thickness of the porous layer is 30 nm to 5 µm. In one embodiment, the porous layer is composed of one or more types of constitutional units that form a fine void structure, and the constitutional units are chemically bonded to each other via catalysis. In one embodiment, the constitutional units of the porous layer are constitutional units having at least one shape selected from the group consisting of particulate, fibrous, rod-like, and tabular shapes. In one embodiment, the bonding between the constitutional units of the porous layer includes hydrogen bonding or covalent bonding. In one embodiment, the porous layer is directly formed on the first main surface of the optical functional layer. Effects of the Invention

[0006] According to an embodiment of the present invention, it is possible to implement a laminated film that includes an optical functional layer having a light redirecting function and an adhesive layer for protecting the optical functional layer, and in which the reduction in function of the optical functional layer caused by the adhesive layer is suppressed. Brief Description of the Drawings

[0007] [Figure 1] Fig. 1 is a schematic cross-sectional view of a laminated film according to one embodiment of the present invention. [Figure 2] Fig. 2 is a schematic cross-sectional view of a laminated film according to another embodiment of the present invention. [Figure 3] It is a schematic cross-sectional view of a laminated film according to still another embodiment of the present invention. [Figure 4] It is a schematic cross-sectional view of a laminated film according to still another embodiment of the present invention. [Figure 5] It is a schematic cross-sectional view of a laminated film according to still another embodiment of the present invention. MODE FOR CARRYING OUT THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0009] A. Overall configuration of laminated film Figure 1 is a schematic cross-sectional view of a laminated film according to one embodiment of the present invention. The illustrated laminated film 100 includes an optical functional layer 10, a porous layer 20, and an adhesive layer 30. The optical functional layer 10 has a first main surface 10a and a second main surface 10b, and the first main surface 10a has an uneven structure. The porous layer 20 is provided on the first main surface 10a of the optical functional layer 10. The adhesive layer 30 is provided on the opposite side of the porous layer 20 from the optical functional layer 10. If necessary, another adhesive layer 40 may be provided as the outermost layer on the second main surface 10b side of the optical functional layer 10. For convenience, the adhesive layer 30 may be referred to as a first adhesive layer, and the another adhesive layer 40 may be referred to as a second adhesive layer. Practically, it is preferable that release liners (not shown) are temporarily attached to the surfaces of the first adhesive layer and the second adhesive layer respectively until the laminated film is put into use. By temporarily attaching the release liners, the first adhesive layer and the second adhesive layer are protected, and roll formation of the laminated film is enabled.

[0010] In embodiments of the present invention, the optical functional layer 10 typically has a light direction conversion function. A laminated film including such an optical functional layer can achieve the following effects depending on the type of optical functional layer: (1) it can surface-decorate various products and improve their design or aesthetic appeal; (2) it can change the color of the displayed image depending on the viewing angle; and (3) it can display different images depending on the viewing angle. Therefore, a laminated film according to embodiments of the present invention may also be called a decorative film, an optical laminate, etc. Typical examples of optical functional layers include reflective hologram film, microlens array film, and prism film. Figures 1 and 2 are schematic cross-sectional views of a laminated film having a reflective hologram film as an optical functional layer, respectively; Figure 3 is a schematic cross-sectional view of a laminated film having another reflective hologram film as an optical functional layer; Figure 4 is a schematic cross-sectional view of a laminated film having a microlens array film as an optical functional layer; and Figure 5 is a schematic cross-sectional view of a laminated film having a prism film as an optical functional layer. According to embodiments of the present invention, even when the first adhesive layer is placed on the first main surface (uneven surface) side of the optical functional layer to protect it, the degradation of the optical functional layer's function due to the first adhesive layer can be suppressed. Furthermore, when the optical functional layer is a hologram film (typically a reflective hologram film), the optical functional layer's function can be effectively expressed without providing a metal layer or metal oxide layer on the first main surface (uneven surface). As a result, the effect of the optical functional layer can be obtained while ensuring transparency, thus significantly expanding the range of application of the laminated film even when a hologram film is used as the optical functional layer. The configurations of the reflective hologram film, microlens array film, and prism film will be described later in sections B-1 to B-3, respectively.

[0011] The height and shape of the unevenness of the first main surface 10a of the optical functional layer 10 can be appropriately set according to the purpose (and therefore the type of optical functional layer). In embodiments of the present invention, the height of the unevenness of the first main surface is 200 nm to 100 μm. When the optical functional layer is a reflective hologram film, the height of the unevenness can typically be less than a few μm or on the order of nanometers. When the optical functional layer is a microlens array film or a prism film, the height of the unevenness can typically be on the order of micrometers (a few μm to about 100 μm). In this specification, "height of unevenness" means the distance from the peak (or top) to the valley (or flat end) of one uneven portion, and if the unevenness has an irregular structure, it means the average distance from the peak (or top) to the valley (or flat end) of each uneven portion. Furthermore, "pitch of irregularities" refers to the distance from one adjacent peak (or peak) to the next, and if the irregularities have an irregular structure, it refers to the average distance from each adjacent peak (or peak) to the next. Details of the height and shape of the irregularities on the first main surface will be described later in sections B-1 to B-3, along with the configuration of the reflective hologram film, microlens array film, and prism film.

[0012] The porous layer 20 preferably has a very low refractive index and very high transparency, as will be described later in section C. By using such a porous layer, appropriate reflection can be achieved at the interface with the optical functional layer, and the transparency of the entire laminated film can be ensured. As a result, the light direction conversion function of the optical functional layer can be fully exercised, and the visibility of the product structure, images, etc. on the side opposite to the viewing side of the optical functional layer can be ensured. The porous layer 20 may be formed on the first main surface 10a of the optical functional layer 10 via an adhesive layer, or it may be formed directly on the first main surface. Preferably, the porous layer is formed directly on the first main surface. With such a configuration, adverse effects caused by the refractive index of the adhesive layer can be avoided. Such direct formation can be achieved, for example, by coating or printing a porous layer forming liquid, as will be described later. The porous layer 20 may have an uneven surface on the side facing the first adhesive layer 30, as shown in Figure 1 (it may follow the unevenness of the first main surface 10a of the optical functional layer 10), or it may have a flat surface on the side facing the first adhesive layer 30, as shown in Figure 2. A configuration in which the surface on the first adhesive layer side is flat, as shown in Figure 2, can be achieved, for example, by increasing the thickness of the porous layer to fill in the recesses.

[0013] The transmittance difference ΔY of the laminated film is preferably -5 to +2, more preferably -5 to +1, and even more preferably -5 to 0. According to the embodiments of the present invention, excellent transparency can be achieved for the laminated film as a whole. As a result, when the laminated film is applied to various products, the visibility of the product structure, images, etc., on the side opposite to the visible side of the optical functional layer can be ensured. The transmittance difference ΔY can be calculated as follows: The transmittance of the laminated film is measured, and the Y value in the XYZ color system is calculated from the transmission spectrum and taken as the Ya value. On the other hand, the Y value of a film with the same configuration except that it does not contain a porous layer is calculated in the same way and taken as the Yb value. The transmittance difference ΔY is calculated as ΔY = Yb - Ya. The transmittance difference ΔY can serve as an indicator of the transparency of the laminated film.

[0014] The haze difference ΔH of the laminated film is preferably 0.1% to 1.0%, more preferably 0.1% to 0.8%, and even more preferably 0.1% to 0.5%. According to embodiments of the present invention, the haze of the laminated film as a whole can be reduced. As a result, when the laminated film is applied to various products, the visibility of the product structure, images, etc., on the side opposite to the visible side of the optical functional layer can be ensured. The haze difference ΔH can be calculated as follows: Measure the haze of the laminated film and define this as the Ha value. On the other hand, measure the haze of a film with the same configuration except that it does not contain a porous layer in the same manner and define this as the Hb value. The haze difference ΔH is calculated as ΔH = Ha - Hb. The transmittance difference ΔY can serve as an indicator of the transparency of the laminated film.

[0015] The above embodiments may be combined as appropriate. For example, the porous layer may be formed to conform to the irregularities of the first main surface of the optical functional layer shown in Figures 3 to 5.

[0016] The components of the laminated film will be explained in detail below.

[0017] B. Optical functional layer In embodiments of the present invention, the optical functional layer 10 may be a reflective hologram film, a microlens array film, or a prism film, as described above. Since these can each be manufactured using materials and methods well known in the industry, descriptions of the constituent materials and manufacturing methods are omitted.

[0018] B-1. Reflective Hologram Film In embodiments of the present invention, by forming a porous layer on the first main surface (uneven surface) of the reflective hologram film, holographic functionality can be achieved without forming a metallic reflective layer on the reflective hologram film. Any suitable configuration can be used for the reflective hologram film. Any suitable fine uneven shape can be used for the uneven shape of the reflective hologram film, which can exhibit functions such as light diffusion, light scattering, light reflection, and light diffraction. Typical examples include Fourier transform structures, lenticular lenses, light diffraction patterns, and moth-eye structures. In addition, uneven shapes such as hairline patterns, matte patterns, serif patterns, and interference patterns may be used, although they do not have a light diffraction function, as they can exhibit unique brilliance. In one embodiment, the reflective hologram film can convert reflected light into diffracted light.

[0019] In one embodiment, as shown in Figure 1, the reflective hologram film may have a corrugated cross-sectional shape with undulations extending in one direction. The direction in which the undulations extend can be appropriately set depending on the purpose. In this case, the pitch of the undulations is preferably 100 nm to 900 nm, more preferably 200 nm to 800 nm, even more preferably 300 nm to 700 nm, and particularly preferably 400 nm to 600 nm. The height of the undulations is, for example, 10 nm to 100 μm, preferably 50 nm to 100 μm, more preferably 100 nm to 2000 nm, even more preferably 200 nm to 700 nm, particularly preferably 220 nm to 600 nm, especially preferably 240 nm to 500 nm, and most preferably 260 nm to 350 nm. In another embodiment, as shown in Figure 3, the reflective hologram film may have a ridged shape with a rectangular cross-section and protrusions extending in one direction at regular intervals (striped in plan view, so-called line and space). The direction in which the ridges extend can be appropriately set depending on the purpose. The width of the protrusions may be, for example, 50 nm to 350 nm, or 100 nm to 300 nm, or 150 nm to 250 nm. In this case, the pitch of the ridges may be, for example, 50 nm to 350 nm, or 100 nm to 300 nm, or 150 nm to 250 nm; the height of the ridges may be the same as when the ridged shape has a corrugated cross-section and extends in one direction, but may be, for example, 50 nm to 350 nm, or 100 nm to 300 nm, or 150 nm to 250 nm. When the reflective hologram film has the configuration shown in Figure 3, the width of the protrusions may be, for example, 500 nm to 1500 nm (1.5 μm), or for example, 700 nm to 1300 nm (1.3 μm), or for example, 900 nm to 1100 nm (1.1 μm).In this case, the pitch of the irregularities may be, for example, 500 nm to 1500 nm (1.5 μm), or for example, 700 nm to 1300 nm (1.3 μm), or for example, 900 nm to 1100 nm (1.1 μm); the height of the irregularities may be the same as when the irregularities have a unidirectional corrugated cross-section, but may also be, for example, 500 nm to 4000 nm (4.0 μm), or for example, 1000 nm (1.0 μm) to 3000 nm (3.0 μm), or for example, 1500 nm (1.5 μm) to 2500 nm (2.5 μm). Regardless of which of the above configurations the reflective hologram film has, as long as the height and pitch of the irregularities are within the above ranges, the light direction conversion function can be maintained well.

[0020] B-2. Microlens array film As shown in Figure 4, the microlens array film has a flat base portion and a lens portion provided on one surface of the base portion. The lens portion is composed of multiple lenses. The lenses constituting the lens portion are typically convex lenses and may have a dome shape, for example, as shown in Figure 4. The lenses may be arranged in a matrix, a predetermined pattern (for example, a stripe pattern), or randomly, as shown in Figure 4. In the embodiment of Figure 4, the pitch of the reliefs (lenses) is preferably 50 μm to 500 μm, more preferably 70 μm to 400 μm, even more preferably 100 μm to 300 μm, and particularly preferably 150 μm to 250 μm. The height of the reliefs (lenses) is preferably 2 μm to 25 μm, more preferably 4 μm to 20 μm, even more preferably 6 μm to 15 μm, and particularly preferably 8 μm to 12 μm. In this case, the diameter of the lens (the diameter of the lens bottom, which is the connection surface with the base) is preferably 20 μm to 200 μm, more preferably 40 μm to 180 μm, even more preferably 60 μm to 150 μm, and particularly preferably 80 μm to 120 μm. When the optical functional layer is a microlens array film, if the pitch, height, and diameter of the lens are within this range, the light direction conversion function can be well maintained.

[0021] B-3. ​​Prism Film As shown in Figure 5, the prism film has a flat base portion and a prism portion. The prism portion is typically composed of multiple unit prisms arranged in a triangular cross-section that is convex on the opposite side from the base portion and extends in one direction. The direction in which the unit prisms extend (the direction of the ridges of the unit prisms) can be appropriately set according to the purpose. In the embodiment of Figure 5, the pitch of the irregularities (unit prisms) is preferably 5 μm to 25 μm, more preferably 8 μm to 20 μm, even more preferably 10 μm to 18 μm, and particularly preferably 12 μm to 16 μm. The height of the irregularities (unit prisms) is preferably 2 μm to 25 μm, more preferably 4 μm to 20 μm, even more preferably 6 μm to 15 μm, and particularly preferably 8 μm to 12 μm. The base length of the unit prism is preferably 5 μm to 25 μm, more preferably 8 μm to 20 μm, even more preferably 10 μm to 18 μm, and particularly preferably 12 μm to 16 μm. When the optical functional layer is a prism film, the pitch, height, and base length of the unit prism can be within these ranges to maintain good light direction conversion functionality.

[0022] C. Porous layer A porous layer typically has voids inside. The porosity of the porous layer is preferably 20% to 60% by volume, more preferably 25% to 55% by volume, even more preferably 30% to 50% by volume, and particularly preferably 35% to 45% by volume. If the porosity is within this range, the refractive index of the porous layer can be set to an appropriate range, and the required mechanical strength can be ensured. The porosity is a value calculated from the refractive index measured with an ellipsometer using the Lorentz-Lorenz formula.

[0023] The refractive index of the porous layer is preferably 1.15 to 1.30, more preferably 1.17 to 1.28, even more preferably 1.18 to 1.26, and particularly preferably 1.19 to 1.24. By providing a porous layer having such a refractive index on the first main surface (uneven surface) of the optical functional layer, appropriate reflection can be achieved at the interface with the optical functional layer. As a result, the light direction conversion function of the optical functional layer can be fully exhibited. Unless otherwise specified, the refractive index refers to the refractive index measured at a wavelength of 550 nm. The refractive index is the value measured by the method described in "(1) Refractive Index of Porous Layer" in the Examples described below.

[0024] The total light transmittance of the porous layer is preferably 85% to 99%, more preferably 87% to 98%, and even more preferably 89% to 97%. By providing a porous layer having such total light transmittance on the first main surface (uneven surface) of the optical functional layer, excellent transparency can be achieved for the entire laminated film. As a result, when the laminated film is applied to various products, the visibility of the product structure, images, etc., on the side opposite to the viewing side of the optical functional layer can be ensured.

[0025] The haze of the porous layer is, for example, less than 5%, preferably less than 3%. On the other hand, the haze is, for example, 0.1% or more, preferably 0.2% or more. By providing a porous layer having such haze on the first main surface (uneven surface) of the optical functional layer, excellent transparency can be achieved for the entire laminated film. As a result, when the laminated film is applied to various products, the visibility of the product structure, images, etc., on the side opposite to the viewing side of the optical functional layer can be ensured. The haze can be measured, for example, by the following method. The void layer (porous layer) is cut to a size of 50 mm x 50 mm and set in a haze meter (Murakami Color Technology Research Institute: HM-150) to measure the haze. The haze value is calculated using the following formula. Haze (%) = [Diffuse transmittance (%) / Total light transmittance (%)] × 100 (%)

[0026] The thickness of the porous layer is preferably 30 nm to 5 μm, more preferably 200 nm to 4 μm, even more preferably 400 nm to 2 μm, and particularly preferably 600 nm to 1 μm. If the thickness of the porous layer is within this range, the light direction conversion function can be well maintained. Note that when the porous layer has a flat surface on the side facing the first adhesive layer 30, as shown in Figures 2 to 5, the thickness of the porous layer refers to the maximum thickness.

[0027] Any suitable configuration can be adopted for the porous layer, as long as it has the desired properties described above. The porous layer can preferably be formed by coating or printing. As materials constituting the porous layer, for example, materials described in International Publication No. 2004 / 113966, Japanese Patent Publication No. 2013-254183, and Japanese Patent Publication No. 2012-189802 can be used. A typical example is a silicon compound. As for silicon compounds, Examples include silica compounds; hydrolyzable silanes, and their partial hydrolysates and dehydration condensates; silicon compounds containing silanol groups; and activated silica obtained by contacting silicates with acids or ion exchange resins. Other examples include organic polymers; polymerizable monomers (e.g., (meth)acrylic monomers and styrene monomers); and curable resins (e.g., (meth)acrylic resins, fluorine-containing resins, and urethane resins). These materials may be used individually or in combination. Porous layers can be formed by coating or printing solutions or dispersions of such materials.

[0028] In a porous layer, the size of the voids (pores) refers to the diameter of the major axis of the void (pore) compared to the diameter of the major axis. The size of the voids (pores) is, for example, 2 nm to 500 nm. The size of the voids (pores) is, for example, 2 nm or more, preferably 5 nm or more, more preferably 10 nm or more, and even more preferably 20 nm or more. On the other hand, the size of the voids (pores) is, for example, 500 nm or less, preferably 200 nm or less, and even more preferably 100 nm or less. The range of the void (pore) size is, for example, 2 nm to 500 nm, preferably 5 nm to 500 nm, more preferably 10 nm to 200 nm, and even more preferably 20 nm to 100 nm. The size of the voids (pores) can be adjusted to a desired size depending on the purpose and application. The size of the voids (pores) can be quantified by the BET test method.

[0029] The size of the voids (pores) can be quantified using the BET test method. Specifically, 0.1 g of the sample (formed void layer) is placed in the capillary of a specific surface area measuring device (Micromeritic: ASAP2020), and then dried under reduced pressure at room temperature for 24 hours to remove gas from within the void structure. Then, nitrogen gas is adsorbed onto the sample to create an adsorption isotherm, and the pore distribution is determined. This allows for the evaluation of the void size.

[0030] Examples of porous layers having voids inside include porous layers and / or porous layers having at least a portion of an air layer. The porous layer typically includes aerogel and / or particles (e.g., hollow fine particles and / or porous particles). The porous layer is preferably a nanoporous layer (specifically, with a diameter of 10 or more fine pores of 90% or more). -1 nm~10 3 It may be a porous layer within the range of nm.

[0031] Any suitable particles can be used as the above-mentioned particles. Typically, the particles consist of silica-based compounds. Examples of particle shapes include spherical, plate-shaped, needle-shaped, string-shaped, and grape cluster-shaped. Examples of string-shaped particles include particles in which multiple spherical, plate-shaped, or needle-shaped particles are linked together in a chain-like manner, short fibrous particles (for example, short fibrous particles described in Japanese Patent Publication No. 2001-188104), and combinations thereof. String-shaped particles may be linear or branched. Examples of grape cluster-shaped particles include those formed by the aggregation of multiple spherical, plate-shaped, and needle-shaped particles to form a grape cluster. The shape of the particles can be confirmed, for example, by observation with a transmission electron microscope.

[0032] The following describes an example of the specific structure of a porous layer. The porous layer in this embodiment consists of one or more types of constituent units that form a fine void structure, and these constituent units are chemically bonded to each other via catalytic action. Examples of the shapes of the constituent units include particulate, fibrous, rod-shaped, and plate-shaped. The constituent units may have only one shape, or they may have a combination of two or more shapes. In the following, we will mainly describe the case in which the porous layer is a void layer of a porous material in which the fine pore particles are chemically bonded to each other.

[0033] Such void layers can be formed in the void layer formation process, for example, by chemically bonding microporous particles together. In embodiments of the present invention, the shape of the "particles" (e.g., the above-mentioned microporous particles) is not particularly limited and may be spherical or of other shapes. In embodiments of the present invention, the above-mentioned microporous particles may be, for example, sol-gel bead-like particles, nanoparticles (hollow nanosilica / nanoballoon particles), nanofibers, etc. Microporous particles typically include inorganic substances. Specific examples of inorganic substances include silicon (Si), magnesium (Mg), aluminum (Al), titanium (Ti), zinc (Zn), and zirconium (Zr). These may be used individually or in combination of two or more. In one embodiment, the above-mentioned microporous particles are, for example, microporous particles of a silicon compound, and the above-mentioned porous body is, for example, a silicone porous body. The above-mentioned microporous particles of a silicon compound include, for example, a pulverized gel-like silica compound. Furthermore, another form of a porous layer having at least a porous layer and / or an air layer is a void layer made of fibrous material such as nanofibers, in which the fibrous material is intertwined to form voids and create a layer. The method for manufacturing such a void layer is not particularly limited and is similar to that of a void layer of a porous material in which the fine porous particles are chemically bonded together. Further other forms include void layers using hollow nanoparticles or nanoclay, and void layers formed using hollow nanoballoons or magnesium fluoride. The void layer may be made of a single constituent material or of multiple constituent materials. The void layer may consist of a single of the above forms or may include multiple of the above forms.

[0034] In this embodiment, the porous structure of the porous body may be, for example, a continuous cell structure in which the pore structure is continuous. A continuous cell structure means, for example, in the above-mentioned porous silicone body, that the pore structure is connected in three dimensions, and can also be described as a state in which the internal voids of the pore structure are continuous. By having a continuous cell structure in the porous body, it is possible to increase the porosity. However, when using closed-cell particles (particles that each have a pore structure) such as hollow silica, a continuous cell structure cannot be formed. On the other hand, when using silica sol particles (pulverized gel-like silicon compounds that form a sol), for example, because the particles have a three-dimensional dendritic structure, it is possible to easily form a continuous cell structure by the sedimentation and accumulation of the dendritic particles in the coating film (a coating film of a sol containing the pulverized gel-like silicon compounds). The porous layer more preferably has a monolithic structure in which the continuous cell structure includes a plurality of pore distributions. A monolithic structure means, for example, a hierarchical structure that includes a structure in which nano-sized fine voids exist and a continuous cell structure in which these nano-voids are aggregated. When forming a monolithic structure, for example, it is possible to achieve both film strength and high porosity by providing fine voids while simultaneously providing high porosity with coarse, interconnected voids. Such a monolithic structure can preferably be formed by controlling the pore distribution of the resulting void structure in the gel (gel-like silicon compound) prior to grinding it into silica sol particles. Alternatively, for example, when grinding a gel-like silicon compound, a monolithic structure can be formed by controlling the particle size distribution of the resulting silica sol particles to a desired size.

[0035] The porous layer contains, for example, pulverized gel-like compounds as described above, and these pulverized particles are chemically bonded to each other. The form of chemical bonding between the pulverized particles in the porous layer is not particularly limited and includes, for example, cross-linking, covalent bonding, and hydrogen bonding.

[0036] The volume-average particle diameter of the pulverized material in the porous layer is, for example, 0.10 μm or more, preferably 0.20 μm or more, and more preferably 0.40 μm or more. On the other hand, the volume-average particle diameter is, for example, 2.00 μm or less, preferably 1.50 μm or less, and more preferably 1.00 μm or less. The range of the volume-average particle diameter is, for example, 0.10 μm to 2.00 μm, preferably 0.20 μm to 1.50 μm, and more preferably 0.40 μm to 1.00 μm. The particle size distribution can be measured, for example, by particle size distribution evaluation devices such as dynamic light scattering and laser diffraction, and by electron microscopes such as scanning electron microscopes (SEM) and transmission electron microscopes (TEM). Note that the volume-average particle diameter is an indicator of the variation in particle size of the pulverized material.

[0037] The type of gel-like compound is not particularly limited. Examples of gel-like compounds include gel-like silicon compounds.

[0038] Furthermore, in the porous layer (void layer), it is preferable that the silicon atoms contained are bonded together by siloxane bonds. Specifically, the proportion of unbonded silicon atoms (i.e., residual silanols) among the total silicon atoms contained in the void layer is, for example, less than 50%, preferably 30% or less, and more preferably 15% or less.

[0039] The following describes an example of a method for forming such a porous layer.

[0040] The method typically includes a precursor formation step of forming a void structure, which is a precursor of a porous layer (void layer), on a resin film, and a crosslinking reaction step of causing a crosslinking reaction within the precursor after the precursor formation step. The method further includes a containing liquid preparation step of preparing a containing liquid containing microporous particles (hereinafter sometimes referred to as "microporous particle containing liquid" or simply "containing liquid"), and a drying step of drying the containing liquid, wherein the precursor formation step chemically bonds the microporous particles in the dried body to form the precursor. The containing liquid is not particularly limited and is, for example, a suspension containing microporous particles. In the following, the case in which the microporous particles are pulverized gel-like compounds and the void layer is a porous body (preferably a silicone porous body) containing pulverized gel-like compounds will be mainly described. However, the porous layer can be formed similarly even when the microporous particles are not pulverized gel-like compounds.

[0041] According to the method described above, for example, a porous layer (void layer) with a very low refractive index is formed. The reason for this is presumed to be as follows. However, this presumption does not limit the method of forming the porous layer.

[0042] Since the above-mentioned pulverized material is obtained by pulverizing a gel-like silicon compound, the three-dimensional structure of the gel-like silicon compound before pulverization is dispersed within the three-dimensional basic structure. Furthermore, in the above method, by coating the crushed gel-like silicon compound onto a resin film, a precursor of a porous structure based on the three-dimensional basic structure is formed. In other words, according to the above method, a new porous structure (three-dimensional basic structure) is formed by coating with the pulverized material, which is different from the three-dimensional structure of the gel-like silicon compound. Therefore, in the void layer obtained in the end, a low refractive index that functions to the same extent as, for example, an air layer can be achieved. Moreover, in the above method, the three-dimensional basic structure is fixed because the pulverized materials are chemically bonded together. Therefore, the void layer obtained in the end can maintain sufficient strength and flexibility despite having a void structure.

[0043] Details of the specific configuration and formation method of the porous layer are described in, for example, International Publication No. WO 2019 / 151073. The description of said publication is incorporated herein by reference.

[0044] D. First pressure-sensitive adhesive layer The first pressure-sensitive adhesive layer has such a hardness that the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer does not permeate into the voids of the porous layer under normal conditions. Typically, the storage elastic modulus of the first pressure-sensitive adhesive layer at 23° C. is 1.0×10 5 (Pa) to 1.0×10 7 (Pa). For example, 1.1×10 5 (Pa) or more, 1.2×10 5 (Pa) or more, 1.3×10 5 (Pa) or more, 1.4×10 5 (Pa) or more, 1.5×10 5 (Pa) or more, 1.6×10 5 (Pa) or more, 1.7×10 5 (Pa) or more, 1.8×10 5 (Pa) or more, 1.9×10 5 (Pa) or more, or 2.0×10 5 (Pa) or more, and 1.0×10 7 (Pa) or less, 5.0×10 6 (Pa) or less, 1.0×10 6 (Pa) or less, or 5.0×10 5 (Pa) or less. It is preferably 1.3×10 5 (Pa) to 1.0×10 6 (Pa), more preferably 1.5×10 5 (Pa) to 5.0×10 5 (Pa). The storage elastic modulus is obtained by reading the value at 23° C. when measured in accordance with the method described in JIS K 7244-1 "Plastics - Test Methods for Dynamic Mechanical Properties" under the condition of a frequency of 1 Hz, in a range of -50° C. to 150° C. at a temperature increase rate of 5° C. / min.

[0045] Any suitable adhesive can be used as the adhesive constituting the first adhesive layer, as long as it has the characteristics described above. Typical adhesives include acrylic adhesives (acrylic adhesive compositions). Typical acrylic adhesive compositions contain (meth)acrylic polymers as the main component (base polymer). (Meth)acrylic polymers may be contained in the adhesive composition in a proportion of, for example, 50% or more by weight, preferably 70% or more by weight, and more preferably 90% or more by weight, of the solid content of the adhesive composition. (Meth)acrylic polymers contain alkyl (meth)acrylate as the main component as monomer units. (Meth)acrylate refers to acrylate and / or methacrylate. Examples of alkyl groups in alkyl (meth)acrylate include linear or branched alkyl groups having 1 to 18 carbon atoms. The average number of carbon atoms in the alkyl group is preferably 3 to 9. Examples of monomers constituting (meth)acrylic polymers include alkyl (meth)acrylates, as well as comonomers such as carboxyl group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, aromatic ring-containing (meth)acrylates, and heterocyclic (meth)acrylates. The comonomers are preferably hydroxyl group-containing monomers and / or heterocyclic (meth)acrylates, and more preferably N-acryloylmorpholine. The acrylic adhesive composition may preferably contain a silane coupling agent and / or a crosslinking agent. Examples of silane coupling agents include epoxy group-containing silane coupling agents. Examples of crosslinking agents include isocyanate-based crosslinking agents and peroxide-based crosslinking agents. Details of such adhesive layers or acrylic adhesive compositions are described, for example, in Japanese Patent No. 4140736, and the contents of said patent publication are incorporated herein by reference.

[0046] The thickness of the first adhesive layer is preferably 3 μm to 30 μm, and more preferably 5 μm to 10 μm. Having the thickness of the first adhesive layer within this range has the advantage of providing sufficient adhesion while minimizing its impact on the optical functional layer.

[0047] E. Second adhesive layer The second adhesive layer is composed of any suitable adhesive. In one embodiment, the second adhesive layer is composed of an adhesive that is soft enough to absorb vibration transmission and suppress damage to the porous layer. The storage modulus of the second adhesive layer at 23°C is, for example, 1.0 × 10⁻⁶. 5 (Pa) or less, for example, 1.0 × 10 5 (Pa) or less, 9.5×10 4 (Pa) or less, 9.0×10 4 (Pa) or less, 8.5×10 4 (Pa) or less, 8.0×10 4 (Pa) or less, 7.5×10 4 (Pa) or less, or 7.0 × 10 4 (Pa) or less, and 1.0 × 10 3 (Pa) or more, 5.0×10 3 (Pa) or more, 1.0×10 4 (Pa) or higher, or 5.0 × 10 4 (Pa) or higher. Preferably 5.0 × 10 3 (Pa) ~9.0 × 10 4 (Pa) or less, more preferably 1.0 × 10 4 (Pa) ~ 8.5 × 10 4 (Pa)

[0048] Any suitable adhesive can be used as the adhesive constituting the second adhesive layer, as long as it has the characteristics described above. Typical examples of adhesives include acrylic adhesives (acrylic adhesive compositions). The acrylic adhesive compositions are as described in Section D above. However, the adhesive constituting the second adhesive layer preferably does not contain heterocyclic (meth)acrylate as a comonomer. Furthermore, the weight-average molecular weight Mw of the base polymer in the adhesive composition is preferably 2,000,000 or less, and more preferably 5,000 to 1,600,000. Details of the second adhesive layer or the acrylic adhesive composition constituting the second adhesive layer are described, for example, in Japanese Patent Application Publication No. 2016-190996, and the description in said publication is incorporated herein by reference.

[0049] The thickness of the second adhesive layer is preferably 5 μm to 300 μm, and more preferably 10 μm to 200 μm. When the thickness of the second adhesive layer is within this range, it is possible to mitigate impacts, especially during lateral vibrations, and reduce damage to the porous layer.

[0050] F. Usage of laminated film As described above, laminated films can typically be used as decorative films or signage. For example, a laminated film can be laminated onto an image display device (typically a smartphone or tablet) and used as signage. Alternatively, a laminated film can be laminated onto the back of a smartphone and used as a decorative film. [Examples]

[0051] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement methods for each characteristic are as follows. Unless otherwise specified, "%" and "parts" in the examples are based on weight.

[0052] (1) Refractive index of porous layer A porous layer was formed on an acrylic film, and then it was cut to a size of 25mm x 50mm and bonded to the surface of a glass plate (thickness: 3mm) using adhesive. The center of the back surface of the glass plate (approximately 20mm in diameter) was colored black with a marker to create a sample that did not reflect light from the back surface of the glass plate. The sample was set in an ellipsometer (JAWoollam Japan: VASE) and the refractive index was measured under conditions of a wavelength of 550nm and an incident angle of 50-80 degrees.

[0053] (2) Peel test The laminated films obtained in the examples and comparative examples were cut into 25 mm x 50 mm sections to serve as test samples. A 180° peel test was performed on these test samples using a tensile testing machine (product name: TCM-1kNB, manufactured by Minebea Co., Ltd.) to separate the porous layer from the optical functional layer. The interlayer adhesion strength (180° peel adhesion strength) (N / 25 mm) between the optical functional layer and the porous layer was measured and evaluated according to the following criteria. The measurements were performed under conditions of 23°C, 50% RH atmosphere, peel angle of 180°, and tensile speed of 300 mm / min. ○ (Good): Adhesion strength of 0.5 (N / 25mm) or higher × (Defective): Adhesion strength is less than 0.5 (N / 25mm)

[0054] (3) Fixedness Measurements were taken in accordance with JIS K 5600. Specifically, a transparent resin film was placed on the outermost layer of the first main surface (uneven surface) of the optical functional layer of the laminated films obtained in the examples and comparative examples. The movement of the resin film was checked using steel wool #0000, a load of 250g, and a stroke of 25mm, and evaluated according to the following criteria. For Comparative Example 5, the obtained laminated film was used as is for the test. ○ (Good): The film moved. × (Defective): The film did not move.

[0055] (4) Changes in visibility depending on the angle A transparent resin film was placed on the outermost layer of the optical functional layer on the first main surface (uneven surface) side of the laminated film obtained in the examples and comparative examples to serve as the test sample. In Comparative Example 5, the obtained laminated film was used as the test sample as is. A light source was placed in the direction normal to the transparent resin film side of the test sample, and a dot image with a diameter of 5 mm and a pitch of 15 mm was placed on the side opposite the transparent resin film of the test sample. The image was observed through the test sample from the normal direction and from the polar angle of 45° to the normal direction, and evaluated according to the following criteria. ○ (Good): The image (dot size, shape, color) changed overall between the normal direction and the 45° direction. △ (Intermediate): The image (dot size, shape, color) changed in some areas in the normal direction and the 45° direction. × (Defective): There was no change in the image (dot size, shape, color) between the normal direction and the 45° direction.

[0056] (5) Transmittance difference ΔY The transmittance of the laminated films obtained in the examples and comparative examples was measured using a spectrophotometer (Hitachi, "U-4100"), and the Y value in the XYZ color system was calculated from the transmission spectrum and defined as the Ya value. On the other hand, the Y value of a film with the same configuration except that it did not contain a porous layer was calculated in the same way and defined as the Yb value. The transmittance difference ΔY was calculated as ΔY = Yb - Ya and evaluated according to the following criteria. Note that the transmittance difference ΔY is an indicator of transparency. ○ (Good): ΔY is less than 2.0 × (Defective): ΔY is 2.0 or higher

[0057] [Manufacturing Example 1] Preparation of coating liquid for forming a porous layer (1) Gelation of silicon compounds Mixture A was prepared by dissolving 0.95 g of methyltrimethoxysilane (MTMS), a precursor of silicon compounds, in 2.2 g of dimethyl sulfoxide (DMSO). To this mixture A, 0.5 g of 0.01 mol / L aqueous oxalic acid solution was added, and the mixture was stirred at room temperature for 30 minutes to hydrolyze the MTMS and produce mixture B containing tris(hydroxy)methylsilane. To 5.5 g of DMSO, 0.38 g of 28% by weight aqueous ammonia and 0.2 g of pure water were added. Then, the above mixture B was added, and the mixture was stirred at room temperature for 15 minutes to gel tris(hydroxy)methylsilane, obtaining mixture C containing a gel-like silicon compound. (2) Aging process The mixed solution C containing the gel-like silicon compound prepared as described above was incubated at 40°C for 20 hours to perform the maturation process. (3) Grinding Next, the gel-like silicon compound, which had been aged as described above, was crushed into granules of several mm to several cm in size using a spatula. Then, 40 g of isopropyl alcohol (IPA) was added to mixture C, and after light stirring, it was left to stand at room temperature for 6 hours to decantate the solvent and catalyst in the gel. By performing the same decantation treatment three times, the solvent was replaced to obtain mixture D. Next, the gel-like silicon compound in mixture D was subjected to pulverization (high-pressure medialess pulverization). For the pulverization (high-pressure medialess pulverization), a homogenizer (manufactured by SMT Co., Ltd., product name "UH-50") was used, and 1.85 g of the gel-like compound and 1.15 g of IPA from mixture D were weighed into a 5 cc screw bottle, and pulverization was performed at 50 W, 20 kHz for 2 minutes. This grinding process pulverized the gel-like silicon compound in the above-mentioned mixture D, resulting in the mixture D becoming a sol E of the pulverized material. The volume-average particle size, which indicates the particle size variation of the pulverized material contained in sol E, was confirmed using a dynamic light scattering nanotrack particle size analyzer (Nikkiso Co., Ltd., UPA-EX150 model) and was found to be between 0.50 and 0.70. Furthermore, to 0.75 g of sol E, 0.062 g of a 1.5 wt% MEK (methyl ethyl ketone) solution of a photobase generator (Wako Pure Chemical Industries, Ltd.: product name WPBG266) and 0.036 g of a 5% MEK solution of bis(trimethoxysilyl)ethane were added in a ratio to obtain a coating liquid for forming a porous layer.

[0058] [Manufacturing Example 2] Preparation of the adhesive constituting the first adhesive layer In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser, 90.7 parts butyl acrylate, 6 parts N-acryloylmorpholine, 3 parts acrylic acid, 0.3 parts 2-hydroxybutyl acrylate, and 0.1 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator were charged together with 100 g of ethyl acetate. After introducing nitrogen gas and purging the mixture with nitrogen while gently stirring, the polymerization reaction was carried out for 8 hours while maintaining the liquid temperature in the flask at around 55°C to prepare an acrylic polymer solution. An acrylic adhesive solution was prepared by adding 0.2 parts isocyanate crosslinking agent (Coronate L, manufactured by Nippon Polyurethane Industries, Ltd., an adduct of trimethylolpropane tolylene diisocyanate), 0.3 parts benzoyl peroxide (Nippon Oil & Fats Co., Ltd., Niper BMT), and 0.2 parts γ-glycidoxypropyl methoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.: KBM-403) to 100 parts of the solids of the obtained acrylic polymer solution. Next, the above acrylic adhesive solution was applied to one side of a silicone-treated polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Polyester Films Co., Ltd., thickness: 38 μm) so that the thickness of the adhesive layer after drying would be 20 μm. The film was then dried at 150°C for 3 minutes to form the adhesive layer. The storage modulus of the obtained adhesive was 1.3 × 10⁻⁶. 5 It was (Pa).

[0059] [Manufacturing Example 3] Preparation of the adhesive constituting the second adhesive layer In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser, 99 parts butyl acrylate, 1 part 4-hydroxybutyl acrylate, and 0.1 parts 2,2'-azobisisobutyronitrile as a polymerization initiator were charged together with 100 parts ethyl acetate. After introducing nitrogen gas and purging the mixture with nitrogen while gently stirring, the polymerization reaction was carried out for 8 hours while maintaining the liquid temperature in the flask at around 55°C to prepare an acrylic polymer solution. To 100 parts of the solid content of the obtained acrylic polymer solution, 0.1 parts isocyanate crosslinking agent (Takenate D110N, trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Takeda Chemical Co., Ltd.), 0.1 parts benzoyl peroxide (Nippon Oil & Fats Co., Ltd., Niper BMT), and 0.2 parts γ-glycidoxypropyl methoxysilane (Shin-Etsu Chemical Co., Ltd.: KBM-403) were added to prepare an acrylic adhesive composition solution. Next, a solution of the above acrylic adhesive composition was applied to one side of a polyethylene terephthalate film (separator film: manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) treated with a silicone release agent, and dried at 150°C for 3 minutes to form an adhesive layer with a thickness of 20 μm on the surface of the separator film. The storage modulus of the obtained adhesive was 8.2 × 10⁻⁶. 4 It was (Pa).

[0060] [Example 1] A transparent reflective hologram film ("SP-3T" manufactured by HOLOGRAM SUPPLY Co., Ltd.) with a corrugated cross-sectional surface was used as the optical functional layer. The surface height of "SP-3T" was 350 nm. The porous layer forming coating liquid prepared in Manufacturing Example 1 was applied to the uneven surface of this hologram film. The coating film was dried by treating it at a temperature of 100°C for 1 minute to form a porous layer (thickness 30 nm) on the hologram film (optical functional layer). The resulting porous layer had a porosity of 60% and a refractive index of 1.15. Next, a first adhesive layer (thickness 10 μm) composed of the adhesive prepared in Manufacturing Example 2 was formed on the surface of the porous layer, and then a second adhesive layer (thickness 28 μm) composed of the adhesive prepared in Manufacturing Example 3 was formed on the substrate surface. In this way, a laminated film having the configuration of a first adhesive layer / porous layer / optical functional layer / second adhesive layer was fabricated. The obtained laminated film was subjected to the evaluations described in (2) to (5) above. The results are shown in Table 1.

[0061] [Example 2] A laminated film was prepared in the same manner as in Example 1, except that the thickness of the porous layer was set to 800 nm. The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0062] [Example 3] A laminated film was prepared in the same manner as in Example 1, except that the thickness of the porous layer was set to 800 nm and the refractive index of the porous layer was set to 1.20. The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1. The refractive index of the porous layer was adjusted by adjusting the amounts of bis(trimethoxysilyl)ethane and photobase generator in the porous layer forming coating solution of Production Example 1.

[0063] [Example 4] A laminated film was prepared in the same manner as in Example 1, except that the thickness of the porous layer was set to 5 μm (5000 nm) and the refractive index of the porous layer was set to 1.20. The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1. The refractive index of the porous layer was adjusted by adjusting the amounts of bis(trimethoxysilyl)ethane and photobase generator in the porous layer forming coating solution of Production Example 1.

[0064] [Example 5] A laminated film was prepared in the same manner as in Example 1, except that the thickness of the porous layer was set to 800 nm and the refractive index of the porous layer was set to 1.30. The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1. The refractive index of the porous layer was adjusted by adjusting the amounts of bis(trimethoxysilyl)ethane and photobase generator in the porous layer forming coating solution of Production Example 1.

[0065] [Example 6] A laminated film was fabricated in the same manner as in Example 3, except that a transparent reflective hologram film (Scivax, "FCLS / 200-4×4") with a striped (line and space) uneven surface in plan view was used instead of "SP-3T" as the optical functional layer. The unevenness height of "FCLS" was 200 nm. The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0066] [Example 7] A laminated film was prepared in the same manner as in Example 3, except that a transparent reflective hologram film (Scivax, "FTLS / 1000 / 2000 / 2000-100×100") with a stripe-like (line & space) uneven surface in plan view was used instead of "SP-3T" as the optical functional layer. The unevenness height of "FTLS" was 2 μm (2000 nm). The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0067] [Example 8] A laminated film was fabricated in the same manner as in Example 3, except that a microlens array film ("HALS," manufactured by Grapac Japan) was used instead of "SP-3T" as the optical functional layer. The surface height of the microlens array film was 10 μm (10,000 nm). The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0068] [Example 9] A laminated film was prepared in the same manner as in Example 3, except that a prism film was used instead of "SP-3T" as the optical functional layer. The unevenness height of the prism film was 10 μm (10,000 nm). The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0069] [Comparative Example 1] A laminated film having the configuration of a first adhesive layer (ends only) / optical functional layer / second adhesive layer was prepared in the same manner as in Example 1, except that the first adhesive layer was directly formed on both ends of the uneven surface of the optical functional layer. In the obtained laminated film, an air layer (void) was formed above the uneven surface of the optical functional layer. The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0070] [Comparative Example 2] A laminated film was prepared in the same manner as in Example 1, except that the thickness of the porous layer was set to 700 nm and the refractive index of the porous layer was set to 1.10. The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1. The refractive index of the porous layer was adjusted by adjusting the amounts of bis(trimethoxysilyl)ethane and photobase generator in the porous layer forming coating solution of Production Example 1.

[0071] [Comparative Example 3] A laminated film was prepared in the same manner as in Example 1, except that a ZrO2 layer (refractive index 2.05, thickness 50 nm) was formed by sputtering instead of a porous layer. The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0072] [Comparative Example 4] A laminated film was prepared in the same manner as in Example 1, except that an SiO2 layer (refractive index 1.47, thickness 50 nm) was formed by sputtering instead of a porous layer. The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0073] [Comparative Example 5] A laminated film having the configuration of transparent resin film / water / optical functional layer / second adhesive layer was prepared in the same manner as in Example 1, except that the uneven surface of the optical functional layer was wet with water and a transparent resin film was laminated onto the surface. The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0074] [Comparative Example 6] A laminated film having a first adhesive layer / optical functional layer / second adhesive layer configuration was prepared in the same manner as in Example 1, except that the first adhesive layer was directly formed on the uneven surface of the optical functional layer. The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0075] [Table 1]

[0076] As is clear from Table 1, according to the embodiments of the present invention, the light direction conversion function of the optical functional layer can be fully exhibited, and the transparency of the laminated film as a whole can be ensured. In particular, even if the optical functional layer is a holographic film, the function can be expressed well without providing a metal layer (reflective layer). Furthermore, according to the embodiments of the present invention, the adhesion between the optical functional layer and the porous layer is strong, so the integrity of the laminated film is also good. [Industrial applicability]

[0077] The laminated film according to the embodiment of the present invention can be suitably used as a decorative film. [Explanation of Symbols]

[0078] 10 Optical functional layer 10a First main surface 10b Second main surface 20 Porous layer 30 First adhesive layer 40 Second adhesive layer 100-layer film

Claims

1. An optical functional layer having a first main surface and a second main surface, wherein the first main surface has an uneven structure with a height of 10 nm to 100 μm; A porous layer provided on the first main surface of the optical functional layer; The porous layer and the adhesive layer provided on the side opposite to the optical functional layer; It has, The optical functional layer is a reflective hologram film, a microlens array film, or a prism film. The refractive index of the porous layer is 1.15 to 1.

30. The storage modulus of the adhesive layer is 1.0 × 10 ５ (Pa) ~1.0×10 ７ (Pa) It is a decorative film or signage. Laminated film.

2. The laminated film according to claim 1, wherein the porous layer contains a silicon compound.

3. The laminated film according to claim 1 or 2, wherein the porosity of the porous layer is 20% by volume to 60% by volume.

4. The laminated film according to any one of claims 1 to 3, wherein the thickness of the porous layer is 30 nm to 5 μm.

5. The laminated film according to any one of claims 1 to 4, wherein the porous layer consists of one or more types of constituent units that form a fine void structure, and these constituent units are bonded to each other by crosslinking, covalent bonding, or hydrogen bonding.

6. The laminated film according to claim 5, wherein the constituent units of the porous layer are constituent units of at least one shape selected from the group consisting of particulate, fibrous, rod-shaped, and plate-shaped.

7. The laminated film according to any one of claims 1 to 6, wherein the porous layer is directly formed on the first main surface of the optical functional layer.

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