Multilayer film and roll

Abstract

Provided is a multilayer film which has high designability, and a roll. This multilayer film has: a light guide member which guides light incident thereon from a light source; and a low refractive index layer which is disposed on one side of the light guide member and has a refractive index of 1.30 or less. The light guide member comprises a light extraction unit that can extract the light guided by the light guide member. The thickness of the light guide member is 1,000 μm or less. The overall thickness from a first surface, which is the surface of the light guide member on the reverse side from the side on which the low refractive index layer is disposed, to a second surface, which is the surface of the low refractive index layer on the reverse side from the light guide member, is 1,500 μm or less.

Description

Laminated films and rolls

[0001] The present invention relates to a laminated film and a roll.

[0002] A method has been proposed for realizing lighting and displays with high design value or entertainment value by arranging laminated films on glass, windows, walls, floors, ceilings, etc.

[0003] For example, Patent Document 1 discloses a configuration having a light guide plate and a first protective plate that is fully adhered to one surface of the light guide plate using a low refractive index resin that has a lower refractive index than the light guide plate.

[0004] Japanese Patent Application Laid-Open No. 2008-299117

[0005] However, in the configuration of Patent Document 1, the thickness of the configuration consisting of the light guide plate and the first protective plate may reduce the design quality of the laminated film.

[0006] An object of the present invention is to provide a laminated film and roll with high designability.

[0007] The laminated film according to one aspect of the present invention comprises a light-guiding member that guides light incident from a light source, and a low-refractive index layer that is arranged on one side of the light-guiding member and has a refractive index of 1.30 or less, wherein the light-guiding member includes a light extraction portion that can extract light guided by the light-guiding member, the light-guiding member has a thickness of 1000 μm or less, and the total thickness from a first surface, which is the surface of the light-guiding member on the side opposite to the side on which the low-refractive index layer is arranged, to a second surface, which is the surface of the low-refractive index layer on the side opposite to the light-guiding member, is 1500 μm or less.

[0008] According to the present invention, it is possible to provide a laminated film and roll with high designability.

[0009] 1 is a schematic cross-sectional view of a laminated film according to an embodiment; FIG. 2 is a schematic plan view of a light extraction layer according to an embodiment; FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2; FIG. 4 is a schematic cross-sectional view of a light extraction unit according to an embodiment; FIG. 5 is a schematic cross-sectional view of a light extraction unit according to Example 1; and FIG. 6 is a schematic plan view of a light extraction unit according to Example 1.

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same components are given the same reference numerals, and duplicated descriptions will be omitted as appropriate.

[0011] The following embodiments are intended to exemplify laminated films embodying the technical concepts of the present invention, and are not intended to limit the present invention to the following embodiments. The dimensions, materials, shapes, relative positions, etc. of the components described below are intended for illustrative purposes only, unless otherwise specified, and are not intended to limit the scope of the present invention. Furthermore, the sizes and positional relationships of components shown in the drawings may be exaggerated for clarity.

[0012] In the drawings shown below, directions are expressed using a Cartesian coordinate system having an X-axis, a Y-axis, and a Z-axis. The X-axis, the Y-axis, and the Z-axis are approximately perpendicular to one another. The direction in which the X-axis arrow points is referred to as the +X direction or +X side, and the direction opposite to the +X direction is referred to as the -X direction or -X side. The direction in which the Y-axis arrow points is referred to as the +Y direction or +Y side, and the direction opposite to the +Y direction is referred to as the -Y direction or -Y side. The direction in which the Z-axis arrow points is referred to as the +Z direction or +Z side, and the direction opposite to the +Z direction is referred to as the -Z direction or -Z side.

[0013] The Z direction along the Z axis indicates the stacking direction of each layer constituting the laminate film according to the embodiment. In this specification, plan view refers to viewing an object from the Z direction. The +Z direction is referred to as "up." The adherend on which the laminate film according to the embodiment is placed is located in the -Z direction as viewed from the laminate film. However, these directional expressions do not limit the directions of the embodiment. In this specification, "thickness" refers to the length of the object in the Z direction, i.e., the stacking direction of each layer. The cross-sectional view shows a cross section parallel to the YZ plane of the laminate film according to the embodiment.

[0014] [Embodiments] <Overall Configuration Example of Laminate Film 10 According to the First Embodiment> FIG. 1 is a cross-sectional view schematically illustrating an example of a laminate film 10 according to a first embodiment. In the example illustrated in FIG. 1, the laminate film 10 includes a light-guiding member 1 that guides light L incident from a light source 50 and a low-refractive index layer 2 that is disposed on one side of the light-guiding member 1 and has a refractive index of 1.30 or less. The low-refractive index layer 2 may be disposed on one side of the light-guiding member 1 via a third adhesive layer 9. The light-guiding member 1 includes a light extraction portion 31 that can extract light L guided by the light-guiding member 1. The thickness t1 of the light-guiding member 1 is 1000 μm or less. The thickness t1 of the light-guiding member 1 is preferably 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, 400 μm or less, or 300 μm or less. The lower limit is not particularly limited, but is preferably 100 μm or more or 200 μm or more. The total thickness t2 from the first surface 11, which is the surface of the light guide member 1 opposite the side where the low refractive index layer 2 is disposed, to the second surface 12, which is the surface of the low refractive index layer 2 opposite the light guide member 1, is 1500 μm or less. The total thickness t2 is preferably 1000 μm or less, 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, 400 μm or less, or 300 μm or less. The lower limit is not particularly limited, but is preferably 100 μm or more or 200 μm or more.

[0015] The laminate film 10 can guide light L incident from the light source 50 using the light guide member 1, and can also extract the light L from the inside of the light guide member 1 to the outside using the light extraction portion 31. The laminate film 10 can illuminate a space in which the laminate film 10 is placed using the light L extracted from the light guide member 1. The light source 50 is, for example, an LED (Light Emitting Diode) light source.

[0016] By setting the thickness t1 of the light guide member 1 to 1000 μm or less and the overall thickness t2 to 1500 μm or less, the presence of the laminate film 10 can be reduced and the laminate film 10 can be made inconspicuous. In this embodiment, by reducing the presence of the laminate film 10, a laminate film 10 with high designability can be provided. Furthermore, the laminate film 10 can enhance the designability of the adherend 20 on which the laminate film 10 is disposed.

[0017] Furthermore, by setting the overall thickness t2 of the laminate film 10 to 1500 μm or less, the laminate film 10 can be made flexible. By making the laminate film 10 flexible, it is possible to reduce placement defects such as the generation of wrinkles or the intrusion of air between the laminate film 10 and the adherend 20 when the laminate film 10 is placed on the adherend 20. Unlike conventional light guide plates that are plate-shaped members, the laminate film 10 can be handled as a roll with the light guide member integrated. In other words, in this embodiment, a roll of laminate film 10 with a high designability can be provided.

[0018] Furthermore, when light L guided through the laminate film 10 reaches the adherend 20 on which the laminate film 10 is disposed, the reaching light L may be scattered by the adherend 20, thereby attenuating the brightness of the illumination light, or the reaching light may be absorbed by the adherend 20, thereby changing the hue of the illumination light. For example, if the adherend 20 is float glass, the float glass absorbs light with a wavelength corresponding to red among the light L that reaches the float glass, causing the illumination light to appear blue. By including the low refractive index layer 2, the laminate film 10 can totally reflect the light L guided by the light-guiding member 1 at the low refractive index layer 2, thereby reducing the light L from reaching the adherend 20. This reduces the brightness attenuation, hue change, etc. of the illumination light caused by the laminate film 10.

[0019] The laminate film 10 can be disposed on an adherend 20. Examples of the adherend 20 include glass, windows, walls, floors, and ceilings. For example, the laminate film 10 is disposed by being attached to the surface of the adherend 20.

[0020] The laminate film 10 can be made of a resin. The laminate film 10 is made of a resin, which increases its flexibility and allows it to be handled in various forms. For example, the laminate film 10 before being placed on the adherend 20 has a release liner on the first adhesive layer 7, allowing it to be handled in the form of a long roll, making it easy to handle. However, the laminate film 10 does not necessarily have to be made of a resin, and at least a portion of it may be made of glass or the like.

[0021] The laminate film 10 can have a first adhesive layer 7 arranged on the low refractive index layer 2 on the side opposite to the light guide member 1. By having the first adhesive layer 7, the laminate film 10 can fix the light guide member 1, the third adhesive layer 9, and the low refractive index layer 2 onto the adherend 20.

[0022] The light-guiding member 1 may have a light extraction layer 3 including a light extraction portion 31 and a transmissive layer 4 that transmits light L incident from a light source 50. By having the light extraction layer 3 and the transmissive layer 4, the light-guiding member 1 can guide the light L incident from the light source 50 and extract the light L from the inside of the light-guiding member 1 to the outside.

[0023] In the laminate film 10, the thickness t3 of the transmissive layer 4 can be set to 30 μm or more. By setting the thickness t3 of the transmissive layer 4 to 30 μm or more, the incidence efficiency of the light L from the light source 50 entering the laminate film 10 can be increased.

[0024] The light extraction portions 31 may be a plurality of internal spaces provided in the light extraction layer 3. When the light extraction portions 31 are a plurality of internal spaces provided in the light extraction layer 3, the laminate film 10 can extract highly directional light L from the inside of the light-guiding member 1 to the outside.

[0025] The laminate film 10 may have a second adhesive layer 8 disposed between the transmissive layer 4 and the light extraction layer 3. The ratio of the thickness of the second adhesive layer 8 to the thickness of the light guide member 1 may be 10% or more, preferably 15% or more and 20%, and the upper limit is not particularly limited, but may be, for example, 50% or less, 40% or less. By disposing such a second adhesive layer 8 between the transmissive layer 4 and the light extraction layer 3, the laminate film 10 can have suitable flexibility.

[0026] In a planar view, the end 3a of the light extraction layer 3 may be located inside the end 4a of the transmissive layer 4. For example, the distance between the end 3a of the light extraction layer 3 and the end 4a of the transmissive layer 4 is 1 mm or more and 100 mm or less. The inside in a planar view refers to the side closer to the center of the laminate film 10 when the laminate film 10 is viewed in a planar view. By having the end 3a of the light extraction layer 3 located inside the end 4a of the transmissive layer 4 in a planar view, a member for allowing light L from the light source 50 to enter the laminate film 10 can be placed in a region 4b of the transmissive layer 4 where the light extraction layer 3 and the transmissive layer 4 do not overlap, thereby increasing the efficiency of incidence of light L from the light source 50 into the laminate film 10. The region 4b is defined by the end 3a of the light extraction layer 3 and the end 4a of the transmissive layer 4.

[0027] The laminate film 10 can have a light incident member 40 that is disposed in a region 4b of the transmissive layer 4 where the light extraction layer 3 and the transmissive layer 4 do not overlap in a planar view, and that allows light L from the light source 50 to be incident on the laminate film 10. With this configuration, the light L from the light source 50 can be more easily incident on the laminate film 10.

[0028] The light extraction layer 3 can include a light extraction portion-forming layer 30 in which the light extraction portions 31 are formed, a substrate 5, and a fourth adhesive layer 6 that is disposed between the light extraction portion-forming layer 30 and the substrate 5 and adhesively bonds the light extraction portion-forming layer 30 to the substrate 5. The laminate film 10 can include a third adhesive layer 9 that is disposed between the transmissive layer 4 and the low refractive index layer 2 and adhesively bonds the transmissive layer 4 to the low refractive index layer 2.

[0029] <Configuration Example of Low Refractive Index Layer 2> The refractive index of the low refractive index layer 2 is preferably 1.25 or less, more preferably 1.20 or less, and even more preferably 1.15 or less. The low refractive index layer 2 is preferably solid, and the refractive index is preferably 1.05 or more. The difference between the refractive index of the transparent layer 4 and the refractive index of the low refractive index layer 2 is preferably 0.20 or more, more preferably 0.23 or more, and even more preferably 0.25 or more. The low refractive index layer 2 having a refractive index of 1.25 or less can be formed, for example, using a porous material. The thickness of the low refractive index layer 2 is, for example, 0.3 μm or more and 5.0 μm or less. The low refractive index layer 2 is used by being coated on a substrate film (not shown), such as an acrylic film. The low refractive index layer 2 and the substrate film (not shown) are arranged in the following order: first adhesive layer 7, low refractive index layer 2, substrate film (not shown), and third adhesive layer 9. The thickness of the substrate film (not shown) is, for example, 5 μm or more and 100 μm or less, preferably 50 μm or less.

[0030] When the low refractive index layer 2 is a porous material having voids therein, its porosity is preferably 35 vol% or more, more preferably 38 vol% or more, and particularly preferably 40 vol% or more. Within this range, a low refractive index layer with a particularly low refractive index can be formed. The upper limit of the porosity of the low refractive index layer is, for example, 90 vol% or less, preferably 75 vol% or less. Within this range, a low refractive index layer with excellent strength can be formed. The porosity here is a value calculated from the refractive index measured with an ellipsometer using the Lorentz-Lorenz formula.

[0031] The low refractive index layer 2 may be, for example, a low refractive index layer having voids as disclosed in International Publication No. 2019 / 146628. The entire disclosure of International Publication No. 2019 / 146628 is incorporated herein by reference. Specifically, the low refractive index layer having voids includes substantially spherical particles such as silica particles, silica particles having micropores, hollow silica nanoparticles, fibrous particles such as cellulose nanofibers, alumina nanofibers, and silica nanofibers, and flat particles such as nanoclay composed of bentonite. In one embodiment, the low refractive index layer having voids is a porous body formed by direct chemical bonding of particles (e.g., microporous particles). Furthermore, at least a portion of the particles constituting the low refractive index layer having voids may be bonded to each other via a small amount (e.g., equal to or less than the mass of the particles) of a binder component. The porosity and refractive index of the low refractive index layer can be adjusted by the particle size, particle size distribution, etc. of the particles constituting the low refractive index layer.

[0032] Methods for obtaining a low refractive index layer having voids include, for example, methods described in JP 2010-189212 A, JP 2008-040171 A, JP 2006-011175 A, WO 2004 / 113966 A, and references thereto. The disclosures of JP 2010-189212 A, JP 2008-040171 A, JP 2006-011175 A, and WO 2004 / 113966 A are incorporated herein by reference in their entirety.

[0033] A porous silica material can be suitably used as the low refractive index layer having voids. Porous silica materials can be produced by, for example, the following methods: A method of hydrolyzing and polycondensing silicon compounds: at least one of hydrolyzable silanes and silsesquioxanes, and at least one of their partial hydrolyzates and dehydration condensates; a method of using at least one of porous particles and hollow microparticles; a method of producing an aerogel layer by utilizing the springback phenomenon; a method of using a pulverized gel obtained by pulverizing a gel-like silicon compound obtained by a sol-gel method and chemically bonding the resulting pulverized microporous particles together with a catalyst or the like; and the like.

[0034] The low refractive index layer 2 is not limited to a porous silica material. The method for producing the low refractive index layer 2 is not limited to the exemplified production methods either, and any production method may be used. Furthermore, the porous layer is not limited to a porous silica material, and the production method is not limited to the exemplified production methods either, and any production method may be used.

[0035] Silsesquioxane is (RSiO １．５ , R is a hydrocarbon group) as a basic structural unit, and ２ However, since it shares with silica the fact that it has a network structure crosslinked by siloxane bonds, porous materials containing silsesquioxane as a basic structural unit are also referred to as porous silica materials or silica-based porous materials in this specification.

[0036] The porous silica material can be composed of microporous particles of a gel-like silicon compound bonded together. Examples of the microporous particles of the gel-like silicon compound include pulverized gel-like silicon compounds. The porous silica material can be formed, for example, by applying a coating liquid containing pulverized gel-like silicon compounds to a substrate. The pulverized gel-like silicon compounds can be chemically bonded (for example, by siloxane bonding) by, for example, the action of a catalyst, light irradiation, heating, etc.

[0037] <Configuration Example of Light Extraction Layer 3> An example of the configuration of the light extraction layer 3 will be described with reference to Figures 2 to 4 in addition to Figure 1. Figure 2 is a plan view schematically showing the light extraction layer 3. Figure 3 is a cross-sectional view schematically showing the light extraction layer 3. Figure 4 is a cross-sectional view schematically showing the light extraction portion 31.

[0038] The light extraction portions 31 included in the light extraction layer 3 may be multiple internal spaces provided in the light extraction layer 3. Each of the multiple internal spaces forms an interface that directs light toward the +Z side by total internal reflection. The internal spaces are sometimes referred to as cavities. The internal spaces have a triangular cross-sectional shape (perpendicular to the X direction and parallel to the YZ plane) with an apex angle on the +Z side, and direct light L propagating in the light-guiding member 1 toward the +Y side toward the +Z side. The light L directed toward the +Z side by the internal spaces is emitted from the laminate film 10. The cross-sectional shape of the internal spaces is not limited to this, and may be trapezoidal or the like as long as it has an interface that directs light L propagating in the +Y direction toward the +Z side. The light emission direction can be changed by changing the cross-sectional shape of the internal spaces (e.g., the direction of the apex angle of the triangle).

[0039] The laminate film 10 extracts the light L guided by the light-guiding member 1 using the light extraction portion 31 and can control the light distribution of the extracted light L, so that the visible light transmittance can be 60% or more and the haze value can be less than 10%. Furthermore, by adjusting the shape and arrangement of the multiple internal spaces in the light extraction portion 31, the light distribution, emission efficiency, and luminance distribution of the light L emitted from the laminate film 10 can be controlled. The light extraction portion 31 is typically a void portion (air cavity) filled with air. However, the air cavity may be filled with a material having a refractive index lower than that of the light extraction portion-forming layer 30 instead of air.

[0040] The light-guiding member 1 has a plurality of internal spaces, which are light extraction portions 31, arranged regularly or randomly along the main surface, i.e., a plane substantially parallel to the XY plane. The size of each internal space can be selected as appropriate as long as it can be installed inside the light extraction portion-forming layer 30. For the light extraction portion-forming layer 30 containing the light extraction portions 31 therein, it is possible to use the light-guiding layers disclosed in, for example, WO 2019 / 182091, WO 2011 / 124765, WO 2019 / 087118, and WO 2011 / 127187. The entire disclosures of these publications are incorporated herein by reference.

[0041] The light extraction layer 3 is produced, for example, by laminating a first film having no pattern and a second film having a desired fine pattern formed thereon by a lamination method or by bonding them with an adhesive (including a pressure-sensitive adhesive).

[0042] The micropatterns in the second film can be formed using laser patterning, direct laser imaging, laser drilling, masked or maskless laser or electron beam irradiation, etc. Individual properties can also be imparted by printing, inkjet printing, screen printing, etc., to change the material or refractive index value. Micro- or nano-dispensing, dosing, direct "writing", discrete laser sintering, micro-EDM (Electrical Discharge Machining), or micromachining, micro-molding, imprinting, embossing, and the like can also be used.

[0043] From the viewpoint of obtaining a good visible light transmittance and haze value, the ratio (occupancy rate) of the area of ​​the multiple internal spaces that are the light extraction portion 31 to the area of ​​the light extraction portion-forming layer 30 in a plan view is preferably 30% or less. The occupation rate of the internal spaces may be uniform, or may increase as the distance from the light source 50 increases so that brightness does not decrease even with increasing distance. The occupation rate of the internal spaces is preferably uniform. From the viewpoint of obtaining good brightness, the occupation rate of the internal spaces is preferably 1% or more. The occupation rate of the internal spaces is preferably 1% or more and 30% or less, with the upper limit being more preferably 25% or less. To obtain a high visible light transmittance, the occupation rate is preferably 10% or less, and more preferably 5% or less.

[0044] The above-described features of the light extraction portion 31 are not limited to the multiple internal spaces formed in the light extraction portion forming layer 30 exemplified here, but are common to various light distribution control structures. As a light distribution control structure formed by multiple internal spaces, for example, the light distribution structure described in International Publication No. 2019 / 087118 can be used.

[0045] The light extraction portion 31 is not limited to a plurality of internal spaces, and may be a plurality of prisms arranged in the light extraction portion forming layer 30. The light extraction portion forming layer 30 may be a prism sheet containing a plurality of prisms therein. A plurality of convex portions (prism portions) may be formed directly on the surface of the light extraction portion forming layer 30. The refractive index of the light extraction portion forming layer 30 is preferably approximately equal to the refractive index of the base material 5 and the fourth adhesive layer 6, and the difference (absolute value) between the refractive indices is preferably 0.15 or less, and more preferably 0.1 or less.

[0046] A light distribution control structure in which the light extraction section 31 is composed of multiple internal spaces has a higher light utilization efficiency than a light distribution control structure such as a prism sheet. Furthermore, the light distribution can be controlled by adjusting the cross-sectional shape (e.g., the angles θa and θb of the inclined surfaces in FIG. 4 ), size, arrangement density, distribution, etc. of the internal spaces. Meanwhile, the visible light transmittance and haze value of the laminate film 10 can be controlled by adjusting the cross-sectional shape, size, arrangement density, and distribution of the multiple internal spaces of the light extraction section 31. The visible light transmittance of the laminate film 10 is 60% or more, preferably 65% ​​or more, 70% or more, 75% or more, or 80% or more. The haze value of the laminate film 10 is less than 10%, and preferably less than 9%, less than 8%, less than 7%, less than 6%, less than 5%, less than 4%, or less than 3%. The haze value can be measured using a haze meter.

[0047] The size and density of the internal spaces affect the haze value. The size of the internal spaces (length M, width W: see Figures 2 to 4) is, for example, preferably 10 μm or more and 500 μm or less, and preferably 1 μm or more and 100 μm or less. From the viewpoint of the light extraction efficiency of the light extraction layer 3, the height H is preferably 1 μm or more and 100 μm or less. The multiple internal spaces are preferably distributed discretely and uniformly, and are preferably arranged periodically, for example, as shown in Figure 2. The pitch Px is preferably, for example, 10 μm or more and 500 μm or less, and the pitch Py is preferably, for example, 10 μm or more and 500 μm or less. The spacing E in Figure 2 is the spacing between multiple internal spaces in the X direction. The spacing D in Figure 2 is the spacing between multiple internal spaces in the Y direction.

[0048] 1 , the transmissive layer 4 can be formed from a film having flat surfaces. The material used for the transmissive layer 4 preferably has a low light absorption coefficient. For example, the transmissive layer 4 can be made of an acrylic film such as PMMA (Poly Methyl Methylate), a cycloolefin film such as COP (Cyclo Olefin Polymer), a polyethylene film such as PET (Polyethylene Terephthalate), or a polycarbonate film.

[0049] From the viewpoint of the incidence efficiency of light from the light source 50 entering the laminate film 10, the thickness t3 of the transmissive layer 4 is preferably 30 μm or more, more preferably 40 μm or more, and even more preferably 60 μm or more or 100 μm or more. On the other hand, from the viewpoint of providing flexibility, the thickness t3 of the transmissive layer 4 is preferably 800 μm or less, more preferably 600 μm or less, even more preferably 500 μm or less or less than 500 μm, and particularly preferably 400 μm or less. The refractive index of the transmissive layer 4 is preferably, for example, 1.45 or more and 1.60 or less. It is preferable that the substrate film on which the low refractive index layer 2 is coated, the light extraction layer 3, and the substrate film to be bonded to the light extraction layer 3 are also similar to the transmissive layer 4.

[0050] <Configuration Example of First to Fourth Adhesive Layers> At least one of an acrylic, polyester, or other pressure-sensitive adhesive and adhesive can be appropriately selected for each of the first adhesive layer 7, the second adhesive layer 8, the third adhesive layer 9, and the fourth adhesive layer 6. The refractive index of each of the first adhesive layer 7, the second adhesive layer 8, the third adhesive layer 9, and the fourth adhesive layer 6 is preferably similar to that of the transparent layer 4, and is preferably, for example, 1.45 or more and 1.60 or less.

[0051] <Configuration Example of Light Incident Member 40> The light incident member 40 has a bottom surface 41 for laminating on a surface such as the top surface of the transmissive layer 4, a light incident surface 42 that receives light L from the light source 50, and an inclined surface 43 that reflects the light L incident on the light incident member 40 from the light source 50 and directs it toward the transmissive layer 4. The inclined surface 43 can control the direction of light incident on the inclined surface 43 at an angle less than the critical angle. The inclined surface 43 may be a flat surface or a curved surface. The curved surface of the inclined surface 43 may be a part of a spherical surface or a part of an aspherical surface. Examples of aspherical surfaces include a parabolic surface. In the example shown in FIG. 1 , the light incident member 40 has a tapered shape that becomes thinner as it moves away from the light source 50.

[0052] When multiple light sources 50 are arranged in a row, the laminated film 10 may have multiple light entrance members 40, or may have a single light entrance member 40 that has a length that allows light from each of the multiple light sources 50 to enter in the direction in which the multiple light sources 50 are arranged.

[0053] The "optical incoupling element" disclosed in International Publication No. 2022 / 030544 can be used for the light incident member 40. The entire disclosure of International Publication No. 2022 / 030544 is incorporated herein by reference.

[0054] The light incident member 40 may be any member that controls the reflection direction of light L incident at an angle less than the critical angle, and may be, for example, a diffraction grating or a directional layer including an optical cavity. The directional layer can be formed, for example, by laminating another film to a film on which an air cavity pattern is formed. The directional layer can be, for example, the "optical incoupling tape" disclosed in WO 2022 / 030543. The entire disclosure of WO 2022 / 030543 is incorporated herein by reference.

[0055] Examples and Comparative Examples Examples and comparative examples will be described below, but the present invention is not limited to these examples.

[0056] <Evaluation Method> (Evaluation of Refractive Index) After forming a low refractive index layer on an acrylic film, it was cut into a size of 50 mm x 50 mm and attached to the surface of a glass plate (thickness: 3 mm) with an adhesive layer. The center of the back surface of the glass plate (diameter: approximately 20 mm) was filled in with black magic marker to prepare a sample in which light was not reflected on the back surface of the glass plate. The prepared sample was placed in an ellipsometer (manufactured by J.A. Woollam Japan: VASE), and the refractive index was measured at a wavelength of 550 nm and an incident angle of 50 degrees to 80 degrees, and the average value was taken as the refractive index.

[0057] (Evaluation of the degree of luminescence) Light from the light source 50 was incident into the laminated films according to the examples and comparative examples, and the light was extracted from the light extraction layer side. The extracted light was evaluated visually for luminous brightness. The evaluation indices "A" to "C" for the degree of luminescence are defined below. A: Good (small attenuation of brightness). B: Fairly good (lower brightness than A, but small attenuation of brightness). C: Poor (larger attenuation of brightness than A and B, and becomes darker as the light is guided in the direction opposite to the side where the light source 50 is located).

[0058] (Evaluation of Emitted Color) Light from the light source 50 was incident into the laminated films according to the examples and comparative examples, and the light was extracted from the light extraction layer side. The emitted color of the extracted light was evaluated visually. The following defines the evaluation indices for emitted color, "o" and "x", as follows: o: White; x: Brightness attenuated, and the light became darker toward the side opposite the light source 50 in the guided direction (this applies to Comparative Examples 1, 2, and 4, where the adherend was high-transmittance glass); or the illumination light became bluish and no longer white (this applies to Comparative Example 3, where the adherend was float glass). High-transmittance glass is glass that absorbs and scatters incident light less. Float glass is glass that absorbs and scatters incident light less than high-transmittance glass.

[0059] (Evaluation of Presence) The presence of the laminate film arranged on the adherend 20 according to the examples and comparative examples was evaluated visually from the side from which light was extracted from the laminate film. The definitions of "good" and "bad" as the evaluation indexes for presence are shown below. Good: No presence of the laminate film is felt. Bad: The presence of the laminate film is felt.

[0060] (Evaluation of Flexibility) The flexibility of the laminated films according to the Examples and Comparative Examples was evaluated sensorily. The definitions of "good" and "bad" as the flexibility evaluation indexes are as follows: Good: Soft enough to be wound into a roll when long. Bad: Hard enough to not be wound into a roll when long.

[0061] <Production Method> (Production Example 1: Preparation of Low Refractive Index Layer with Substrate Film) 8 parts of methyltrimethoxysilane were dissolved in 18 parts of dimethyl sulfoxide (DMSO). 4 parts of a 0.01 mol / L aqueous oxalic acid solution were added to this mixture, and the mixture was stirred at room temperature for 30 minutes to hydrolyze the methyltrimethoxysilane. 65 parts of dimethyl sulfoxide, 3 parts of 28% aqueous ammonia, and 2 parts of pure water were then added, followed by stirring at room temperature for 15 minutes and heat aging at 40°C for 20 hours to obtain a gel-like compound.

[0062] The gel-like compound obtained by the heat aging was crushed into granules of several mm to several cm in size, and isopropyl alcohol (IPA) was added in an amount four times the amount of the gel. After lightly stirring, the mixture was left to stand at room temperature for six hours, and the solvent and catalyst in the gel were decanted. The same decantation process was repeated three times to complete the solvent substitution.

[0063] The gel-like compound obtained by solvent substitution was subjected to high-pressure, media-less pulverization (homogenizer (trade name UH-50, manufactured by SMT Corporation)) to produce a sol. The volume-average particle size, which indicates the particle size variation of the sol, was confirmed using a dynamic light scattering Nanotrac particle size analyzer (manufactured by Nikkiso Co., Ltd., trade name UPA-EX150), and was found to be 0.50 μm or more and 0.70 μm or less. Furthermore, a 1.5 wt% isopropyl alcohol solution of a photobase generating catalyst (Wako Pure Chemical Industries, Ltd.: trade name WPBG266) was prepared, and 0.031 parts of the catalyst were added to 0.75 parts of the sol particle liquid, and 0.018 parts of 5% bis(trimethoxysilyl)ethane were added to prepare a coating liquid.

[0064] Next, the low refractive index layer-forming coating liquid was applied to a substrate film (PMMA: Poly Methyl Methylacrylate, thickness 30 μm) so that the thickness after curing would be 1 μm, and the coating was heated and dried to cure, thereby obtaining a low refractive index layer (thickness 31 μm) with the substrate film. The refractive index of the obtained low refractive index layer was 1.16.

[0065] (Production Example 2: Preparation of low refractive index layer with substrate film) 13 parts of water were added to 20 parts of alumina sol liquid (4.9% concentration: manufactured by Kawaken Fine Chemicals), and the mixture was heated at 80°C, followed by the addition of 3 parts of NH3. A gel-like compound was obtained by further heating at 80°C for 10 hours. The same procedure as in Production Example 1 was carried out, except that this gel-like compound was used instead of the gel-like compound of Production Example 1, to obtain a low refractive index layer with a substrate film. The refractive index of the obtained low refractive index layer was 1.24.

[0066] (Production Example 3: Preparation of low refractive index layer with substrate film) A low refractive index layer with a substrate film was obtained by the same operation as in Production Example 1, except that a thermosetting silicone material (OF-127 manufactured by Shin-Etsu Chemical Co., Ltd.) having a refractive index of 1.41 described in JP 2008-299117 A was used. The refractive index of the obtained low refractive index layer was 1.41.

[0067] (Production Example 4: Preparation of Light Extraction Section-Forming Layer) A light extraction section-forming layer having a recess on one main surface was prepared according to the method described in JP-A 2013-524288. Specifically, the process is as follows. The surface of a PMMA film (thickness 128 μm) was coated with lacquer (Finecure RM-64 manufactured by Sanyo Chemical Industries, Ltd.), a predetermined optical pattern was embossed on the film surface containing the lacquer, and the lacquer was then cured. This produced a light extraction section-forming layer having a cross-sectional shape as shown in FIG. 5 and including a recess having a planar view shape as shown in FIG. 6. Here, FIG. 5 is a cross-sectional view schematically showing an example of a light extraction section in the example. FIG. 6 is a plan view schematically showing an example of a light extraction section in the example.

[0068] The height (depth) H of the recesses as the fabricated light extraction portions was 10 μm, the width W was 10.5 μm, the inclination angle θc of the first inclined surface ISa was 49°, and the inclination angle θd of the second inclined surface ISb was 80°. Furthermore, the pitch Py of the recesses in the direction in which the light is guided (e.g., the Y direction) was 300 μm, and the pitch Px in the direction perpendicular to the direction in which the light is guided (e.g., the X direction) was 300 μm.

[0069] Example 1 A fourth adhesive layer 6 (made of polyester resin, thickness 7 μm) was placed on the main surface of the light extraction layer 3 produced in Production Example 4 on which the recesses were formed, and a substrate 5 (made of PMMA, thickness 30 μm) was laminated via the fourth adhesive layer 6 to obtain a light extraction layer 3 (thickness 165 μm). Further, a transmission layer 4 (made of PMMA, thickness 130 μm) was laminated via a second adhesive layer 8 (manufactured by Nitto Denko Corporation, CS9864, thickness 100 μm) on the opposite side of the fourth adhesive layer 6 of the substrate 5, to obtain a light guide member 1 (thickness 395 μm). Further, the substrate film side of the low refractive index layer 2 with the substrate film produced in Production Example 1 was laminated via a third adhesive layer 9 (made of acrylic resin, thickness 10 μm) on the opposite side of the second adhesive layer 8 of the transmission layer 4 to obtain a laminate film 10 (thickness 456 μm). Furthermore, a first adhesive layer 7 (made of an acrylic resin, having a thickness of 10 μm) was placed on the opposite side of the low refractive index layer 2 with the substrate film (30 μm) attached thereto, and the laminated film 10 was placed on a highly transmittant glass (manufactured by Nippon Sheet Glass Co., Ltd., having a thickness of 5 mm) as an adherend 20 via the first adhesive layer 7.

[0070] In this manner, a laminated film 10 was produced, which had a light extraction layer 3, a fourth adhesive layer 6, a substrate 5, a second adhesive layer 8, a transparent layer 4, a third adhesive layer 9, a low refractive index layer 2 with a substrate film, and a first adhesive layer 7.

[0071] In this example, as shown in FIG. 1 , the laminate film 10 was formed so that the end 3 a of the light extraction layer 3 was located more inward than the end 4 a of the transmissive layer 4. A light incident member 40 was disposed in a region 4 b of the transmissive layer 4 where the light extraction layer 3 and the transmissive layer 4 do not overlap in a planar view. The light incident member 40 allowed light from the light source 50 to enter the laminate film 10. The length of the region 4 b in the Y direction was 50 mm. For example, the light incident member 40 was disposed on the transmissive layer 4 by adhesively adhering it to the transmissive layer 4 via an adhesive layer. The light source 50 was also disposed so that light could enter the laminate film 10 through the light incident member 40. The laminate film 10 disposed on the adherend 20 was subjected to the above-described evaluation.

[0072] Example 2 The same procedure as in Example 1 was carried out except that the low refractive index layer with the base film prepared in Production Example 2 was used instead of Production Example 1.

[0073] Example 3 The example was the same as Example 1, except that a light source 50 was disposed at the end 4 a of the transmissive layer 4 instead of the light incident member 40 .

[0074] (Example 4) The procedure was the same as Example 1, except that the second adhesive layer 8 was replaced with another second adhesive layer (CS9862 manufactured by Nitto Denko Corporation, thickness 50 μm), and the light extraction portion forming layer 30 was replaced with a thinner light extraction portion forming layer (thickness 60 μm).

[0075] Example 5 The same procedure as in Example 1 was carried out except that the transparent layer 4 was replaced with a thinner transparent layer (thickness: 30 μm).

[0076] (Example 6) The same as Example 1 was performed except that the transmissive layer 4 was replaced with a thinner transmissive layer (thickness 40 μm), and the light incident member 40 was replaced with a light source 50 disposed at the end of a transmissive layer thinner than the transmissive layer 4.

[0077] Comparative Example 1 The procedure was the same as in Example 1, except that the low refractive index layer with the base film prepared in Production Example 3 was used instead of Production Example 1.

[0078] Comparative Example 2 The procedure was the same as in Example 1, except that the low refractive index layer 2 with the base film and the first adhesive layer 7 were not provided.

[0079] (Comparative Example 3) The same procedure as in Example 1 was repeated, except that float glass (manufactured by Nippon Sheet Glass Co., Ltd., thickness 5 mm) was used instead of the high-transmittance glass, and the low-refractive index layer 2 with the substrate film and the first adhesive layer 7 were not provided.

[0080] (Comparative Example 4) The comparative example was the same as Example 1, except that a thicker transmissive layer (thickness 2000 μm) was used instead of the transmissive layer 4, and a light source 50 was placed at the end of a transmissive layer thicker than the transmissive layer 4 instead of the light incident member 40.

[0081] Table 1 shows a list of the conditions and evaluation results for each of Examples 1 to 6 and Comparative Examples 1 to 3. In the "Flexibility / Presence" section in Table 1, if both flexibility and presence were "○", the rating was "○", and if at least one of flexibility and presence was "×", the rating was "×".

[0082]

[0083] As shown in Table 1, in Examples 1 to 4, the "degree of luminescence" was "A," the "luminous color" was "Good," and the "flexibility / presence" was "Good." In Examples 5 and 6, the "degree of luminescence" was "B," the "luminous color" was "Good," and the "flexibility / presence" was "Good."

[0084] On the other hand, in Comparative Examples 1 and 2, the "degree of luminescence" was "C," the "luminous color" was "×," and the "flexibility / presence" was "◯." In Comparative Example 3, the "degree of luminescence" was "A," the "luminous color" was "×," and the "flexibility / presence" was "◯." In Comparative Example 4, the "degree of luminescence" was "A," the "luminous color" was "○," and the "flexibility / presence" was "×."

[0085] As described above, it was found that in Examples 1 to 6, laminated films having good "luminous intensity," "luminous color," and "flexibility / presence" were obtained.

[0086] [Various Modifications] The laminate film 10 may also have an adherend 20 arranged on the side of the low refractive index layer 2 opposite to the light guide member 1. By having the laminate film 10 have the adherend 20, it is possible to provide a laminate film 10 with an adherend 20 that has excellent design properties.

[0087] The adherend 20 is not limited to glass, but may also be an electronic substrate such as a liquid crystal cell, or a non-light-transmitting member such as a ceiling, wall, or floor. The light extraction layer 3 is not limited to extracting light L to the side opposite to the side on which the adherend 20 is located, but may also extract light L to the side on which the adherend 20 is located. In this case, if the adherend 20 has high light transmittance, the extracted light L may pass through the adherend 20, or if the adherend 20 has low light transmittance, the adherend 20 may reflect the light. The light extraction layer 3 may be disposed between the transmissive layer 4 and the low refractive index layer 2.

[0088] A pattern layer for improving brightness uniformity may be provided between the transmissive layer 4 and the light extraction layer 3. The optical coupling layer disclosed in International Publication No. WO 2022 / 025067 can be used for such a pattern layer. The entire disclosure of International Publication No. WO 2022 / 025067 is incorporated herein by reference. The pattern layer is formed of a first portion having a lower refractive index than the transmissive layer 4 and a second portion having a higher refractive index than the first portion. The first portion may be a low refractive index layer such as the low refractive index layer 2, or may be an air cavity. The second portion may be formed by an adhesive layer, or may be formed by filling voids in the low refractive index layer with a material such as an adhesive. From the perspective of reducing the presence of the laminate film 10, even when the pattern layer is present, the thickness of the light guide member 1 is preferably 1000 μm or less, and more preferably 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, 400 μm or less, or 300 μm or less.

[0089] A substrate film may be further disposed on the side of the light extraction layer 3 opposite to the side on which the transmission layer 4 is located. This substrate film may be a hard coat layer or an anti-reflection layer. Furthermore, a low refractive index layer may be present between the light extraction layer 3 and the substrate film. From the viewpoint of reducing the presence of the laminate film 10, even when these components are present, the thickness of the light guide member 1 is preferably 1000 μm or less, and more preferably 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, 400 μm or less, or 300 μm or less.

[0090] The transmissive layer 4 and the light extraction layer 3 are not limited to being separate films, but may be integrated with the light extraction layer 3. For example, a transmissive layer 4 having patterned recesses formed therein can function as both the transmissive layer 4 and the light extraction layer 3.

[0091] The light extraction layer 3 does not necessarily have to include the substrate 5. The light guide member 1 does not necessarily have to include the second adhesive layer 8.

[0092] In the above description, the low refractive index layer 2 is coated on a substrate film (not shown), and the first adhesive layer 7, the low refractive index layer 2, the substrate film (not shown), and the third adhesive layer 9 are arranged in this order. However, the order of the low refractive index layer 2 and the substrate film (not shown) may be reversed, or the substrate film (not shown) may be omitted. Alternatively, the low refractive index layer 2 may be coated directly on the light guide member 1, i.e., the transmissive layer 4, and the third adhesive layer 9 and the substrate film (not shown) may be omitted.

[0093] When handled as a roll, the laminate film may be a laminate film of the light guide member and the low refractive index layer, or may be a laminate film of the light guide member, the low refractive index layer, and the first pressure-sensitive adhesive layer. When handled as a roll, a surface protection film having a substrate and a pressure-sensitive adhesive may be attached to the surface of the light guide member or the low refractive index layer as appropriate. Also, a release liner may be attached to the surface of the first pressure-sensitive adhesive layer.

[0094] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

[0095] The ordinal numbers, quantities, and other figures used in the description of the embodiments are all provided as examples to specifically explain the technology of the present invention, and the present invention is not limited to the illustrated figures. Furthermore, the connection relationships between the components are provided as examples to specifically explain the technology of the present invention, and do not limit the connection relationships that realize the functions of the present invention.

[0096] The laminate film according to the embodiment has high designability, and can be used in applications such as illuminating the interior or exterior space of a building by combining it with a light source and placing it on architectural components such as glass, windows, walls, floors, and ceilings, while enhancing the design of the architectural components. Furthermore, by placing it on a partition, it can be used as an interior partition or to conceal a desired space, while enhancing the design of the partition. Furthermore, by placing it on the glass substrate of a display device such as a liquid crystal panel or an organic EL (Electro Luminescence) display panel, it can be used for backlighting in the display device, while enhancing the design of the display device. Furthermore, the laminate film according to the embodiment can provide new uses in addition to those described above.

[0097] A surface lighting device can also be configured using the laminate film of this embodiment and a light source arranged near an end of the laminate film. Light from the light source may enter the interior of the laminate film from an end face of the laminate film along the lamination direction, or from a surface (main surface of the laminate film) intersecting the end face. Light from the light source may enter the interior of the laminate film directly without passing through a light incident member, or may enter the interior of the laminate film via a light incident member.

[0098] This application claims priority based on Japanese Patent Application No. 2023-092333, filed with the Japan Patent Office on June 5, 2023, and includes the entire contents of this Japanese patent application.

[0099] The present invention includes, for example, the following aspects. <1> A laminate film including a light-guiding member that guides light incident from a light source and a low-refractive index layer that is disposed on one side of the light-guiding member and has a refractive index of 1.30 or less, wherein the light-guiding member includes a light extraction portion that can extract the light guided by the light-guiding member, the light-guiding member having a thickness of 1000 μm or less, and an overall thickness from a first surface that is the surface of the light-guiding member opposite the side on which the low-refractive index layer is disposed to a second surface that is the surface of the low-refractive index layer opposite the light-guiding member, of 1500 μm or less. <2> The laminate film according to <1>, further including a first adhesive layer that is disposed on the low-refractive index layer opposite the light-guiding member. <3> The laminate film according to any one of <1> to <3>, wherein the light-guiding member includes a light extraction layer that includes the light extraction portion and a transmission layer that transmits light incident from the light source. <4> The laminate film according to <3>, wherein the thickness of the transmissive layer is 30 μm or more. <5> The laminate film according to <3> or <4>, wherein the light extraction portions are a plurality of internal spaces provided in the light extraction layer. <6> The laminate film according to any one of <3> to <5>, wherein a second adhesive layer is disposed between the transmissive layer and the light extraction layer, and wherein the ratio of the thickness of the second adhesive layer to the thickness of the light-guiding member is 10% or more. <7> The laminate film according to any one of <3> to <6>, wherein, in a planar view, an end of the light extraction layer is located inside an end of the transmissive layer. <8> The laminate film according to <7>, wherein a light incident member is disposed in a region of the transmissive layer where the light extraction layer and the transmissive layer do not overlap in a planar view, and which allows light from the light source to enter. <9> The laminate film according to any one of <1> to <8>, wherein an adherend is disposed on the side of the low refractive index layer opposite the light-guiding member. <10> A roll in which the laminated film according to any one of <1> to <9> is wound.

[0100] LIST OF SYMBOLS 1 Light guide member 11 First surface 12 Second surface 2 Low refractive index layer 3 Light extraction layer 30 Light extraction portion forming layer 31 Light extraction portion 3a End 4 Transmitting layer 4a End 4b Region 5 Substrate 6 Fourth adhesive layer 7 First adhesive layer 8 Second adhesive layer 9 Third adhesive layer 10 Laminated film 20 Adherend 40 Light incident member 41 Bottom surface 42 Light incident surface 43 Inclined surface 50 Light source L Light t1 Thickness of light guide member t2 Total thickness of laminated film t3 Thickness of transmissive layer D Spacing between multiple internal spaces in the Y direction E Spacing between multiple internal spaces in the X direction ISa First inclined surface ISb Second inclined surface M Length Px Pitch between multiple internal spaces in the X direction Py Pitch between multiple internal spaces in the Y direction H Height W Width θa, θb angle θc, θd tilt angle

Claims

1. A laminated film comprising: a light-guiding member that guides light incident from a light source; and a low refractive index layer that is arranged on one side of the light-guiding member and has a refractive index of 1.30 or less; the light-guiding member includes a light extraction portion that is capable of extracting light guided by the light-guiding member; the light-guiding member has a thickness of 1000 μm or less; and the total thickness from a first surface, which is the surface of the light-guiding member on the side opposite to the side on which the low refractive index layer is arranged, to a second surface, which is the surface of the low refractive index layer on the side opposite to the light-guiding member, is 1500 μm or less.

2. The laminated film according to claim 1, further comprising a first adhesive layer disposed on the low refractive index layer opposite to the light guide member.

3. The laminated film according to claim 1 or 2, wherein the light guide member has a light extraction layer including the light extraction portion, and a transmission layer that transmits the light incident from the light source.

4. The laminated film according to claim 3, wherein the thickness of the transparent layer is 30 μm or more.

5. The laminated film according to claim 3, wherein the light extraction portion is a plurality of internal spaces provided in the light extraction layer.

6. The laminated film according to claim 3, further comprising a second adhesive layer disposed between the transparent layer and the light extraction layer, the ratio of the thickness of the second adhesive layer to the thickness of the light guide member being 10% or more.

7. The laminate film according to claim 3, wherein, in a plan view, an end of the light extraction layer is located inside an end of the transmission layer.

8. The laminate film according to claim 7, further comprising a light entrance member arranged in a region of the transmissive layer where the light extraction layer and the transmissive layer do not overlap in a plan view, for allowing light from the light source to enter.

9. The laminate film according to claim 1 or 2, further comprising an adherend arranged on the side of the low refractive index layer opposite the light guide member.

10. A roll of the laminated film according to claim 1 or 2.

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