Laminate film, manufacturing method of laminate film, optical member and manufacturing method of optical member

Abstract

To provide a laminate film capable of realizing an optical member capable of preventing a defect in a pattern shape while realizing improved productivity.SOLUTION: A laminate film includes: a substrate including a first principal surface and a second principal surface opposite to the first principal surface; and a rugged layer disposed on the first principal surface. The rugged layer includes: protrusions composed of a surface protective film; and recesses composed of a low refractive index part and arranged between protrusions. The low refractive index part has a porous structure. A ratio of a sum total area of the recesses is 50% or less with regard to a total area of the rugged layer viewed in a thickness direction of the laminate film.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a laminated film, a method for manufacturing a laminated film, an optical member, and a method for manufacturing an optical member. [Background technology]

[0002] It is known that disposing a low-refractive index layer having a porous structure on a substrate improves the light reflection efficiency and improves and maintains the intensity of light emitted from optical components such as lighting devices equipped with a light source and a light guide layer. Furthermore, optical components capable of distributing light by partially disposing a low-refractive index layer on a substrate to change the light extraction position have been produced. By using such an optical component, an optical component can be realized that can efficiently distribute light irradiated onto the light guide layer and extract desired light. For example, in order to partially arrange a low refractive index layer, a technique has been proposed in which a material having a porous structure is applied to the entire surface of a substrate, and then an ink (paint) containing a curable resin is selectively applied to form a low refractive index layer having a pattern shape on the substrate (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 182100 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when producing a low refractive index layer having a pattern shape such as that of the above-mentioned optical member, productivity may decrease due to loss of material caused by filling with ink, etc. Furthermore, defects may occur in the pattern shape of the low refractive index layer. An object of the present invention is to provide a laminated film that can suppress defects in the pattern shape of a low refractive index portion and can realize an optical member that allows for improved productivity. [Means for solving the problem]

[0005] [1] A laminated film according to an embodiment of the present invention comprises a substrate having a first main surface and a second main surface opposite the first main surface; and a concave-convex layer disposed on the first main surface. The concave-convex layer has convex portions formed by a surface protection film and concave portions formed by low refractive index portions disposed between the convex portions. The low refractive index portions have a porous structure. The ratio of the total area of ​​the concave portions to the total area of ​​the concave-convex layer as viewed in the thickness direction of the laminated film is 50% or less. [2] In the laminated film according to the above [1], the low refractive index portion may be disposed on a first main surface of the substrate. [3] In the laminated film according to the above [1] or [2], the low refractive index portion may be formed in an island shape in a plan view when viewed from the thickness direction. [4] In the laminated film according to the above item [3], the low refractive index portion may have an equivalent diameter of an equal-circumference ellipse in plan view of 1 μm or more and 500 μm or less. [5] In the laminated film according to any one of [1] to [4] above, the surface protective film may include a film layer and a pressure-sensitive adhesive layer disposed on the substrate side of the film layer, and the thickness of the low refractive index portion may be smaller than the thickness of the film layer. [6] In the laminated film according to the above item [5], the thickness of the low refractive index portion may be smaller than the thickness of the pressure-sensitive adhesive layer. [7] According to another aspect of the present invention, there is provided a method for producing a laminated film according to any one of the above items [1] to [6]. The method for producing the laminated film includes a through-hole forming step of forming a through-hole in the surface protective film, a disposing step of disposing the surface protective film having the through-hole formed therein on the substrate, and a low-refractive-index portion forming step of forming a low-refractive-index portion by applying a low-refractive-index portion forming material to an area of ​​the substrate exposed by the through-hole. [8] In the method for producing a laminated film according to the above item [7], the low refractive index portion forming step may include applying the low refractive index portion forming material by spraying. [9] An optical element according to another aspect of the present invention includes a substrate and a plurality of low refractive index portions disposed on a main surface of the substrate. The low refractive index portions have a porous structure. A ratio of the area of ​​the low refractive index portions to the total area of ​​the main surface of the substrate and the low refractive index portions, as viewed in the thickness direction of the optical element, is 50% or less.

[10] In the optical member according to [9] above, the low refractive index portions may be formed in an island shape in a plan view when viewed in the thickness direction.

[11] In the optical member according to

[10] above, the low refractive index portion may have an equivalent diameter of an equal-circumference ellipse in the plan view of 1 μm or more and 500 μm or less.

[12] According to another aspect of the present invention, there is provided a method for producing an optical member according to any one of [9] to

[11] above. The method for producing an optical member includes: a through-hole forming step of forming a through-hole in a surface protective film that protects the substrate; a disposing step of disposing the surface protective film having the through-hole formed therein on the substrate; a low-refractive-index portion forming step of forming a low-refractive-index portion by applying a low-refractive-index portion forming material to an exposed portion of the substrate due to the through-hole; and a peeling step of peeling off the surface protective film after the low-refractive-index portion forming step.

[13] In the method for producing an optical member according to

[12] above, the low refractive index portion forming step may include applying the low refractive index portion forming material by spraying. [Effects of the Invention]

[0006] According to the embodiments of the present invention, a laminated film capable of realizing an optical member capable of suppressing defects in pattern shape and enabling improvement in productivity, and an optical member in which defects in pattern shape are suppressed, can be obtained. [Brief explanation of the drawings]

[0007] [Figure 1A] 1 is a schematic cross-sectional view of a laminated film according to one embodiment of the present invention. [Figure 1B] FIG. 2 is a schematic plan view of the laminated film according to the embodiment of the present invention, as viewed from the thickness direction. [Figure 2A] 1 is a schematic cross-sectional view of an optical element according to one embodiment of the present invention. [Figure 2B] FIG. 2 is a schematic plan view of the optical member according to the embodiment of the present invention as viewed in the thickness direction. [Figure 3A] FIG. 2 is a schematic partial perspective view showing an example of a part of one step (arrangement step) of the method for producing the laminated film according to the embodiment of the present invention. [Figure 3B] FIG. 2 is a schematic partial cross-sectional view showing an example of a part of one step (arrangement step) in the method for producing the laminated film according to the embodiment of the present invention. [Figure 3C] FIG. 2 is a schematic cross-sectional view showing an example of a part of one step (low refractive index portion forming step) in the method for producing the laminated film according to the embodiment of the present invention. [Figure 4] FIG. 2 is a schematic cross-sectional view showing an example of a part of one step (peeling step) of the method for manufacturing an optical member according to the embodiment of the present invention. [Figure 5] FIG. 2 is a schematic partially enlarged plan view of a laminated film according to an embodiment of the present invention, viewed from the thickness direction, illustrating the concept of dot diameter and pitch in the laminated film. [Figure 6A] FIG. 2 is a diagram showing the surface state in a plan view of the laminated film in Example 1, which was observed with a laser microscope and image-processed. [Figure 6B] FIG. 10 is a diagram showing the surface state in a plan view of the laminated film in Example 2, which was observed with a laser microscope and image-processed. [Figure 6C] FIG. 10 is a diagram showing the surface state in a plan view of the laminated film in Example 3, which was observed with a laser microscope and image-processed. [Figure 6D] FIG. 10 is a diagram showing the surface state in a plan view of the laminated film in Example 4, which was observed with a laser microscope and image-processed. DETAILED DESCRIPTION OF THE INVENTION

[0008] Representative embodiments of the present invention will be described below, but the present invention is not limited to these embodiments. For ease of viewing and understanding, the drawings are drawn schematically or conceptually, and the length, width, shape, size, ratio, direction, number, etc. may differ from the actual ones, and may not correspond to each other between the drawings. In this specification, "A and / or B" means either "A," "B," or "A and B."

[0009] A. Overall configuration First, the overall configuration of the laminated film and the optical member will be described.

[0010] A-1. Overall structure of laminated film 1A is a schematic cross-sectional view of a laminated film according to one embodiment of the present invention. The laminated film 100 shown in the figure includes a substrate 10 having a first main surface 10a and a second main surface 10b opposite the first main surface 10a; and a concave-convex layer 2 disposed on the first main surface 10a. The concave-convex layer 2 has convex portions 2a formed by a surface protection film 30 and concave portions 2b formed by low-refractive-index portions 20 disposed between the convex portions 2a. The low-refractive-index portions 20 have a porous structure. In this embodiment of the present invention, the ratio of the total area of ​​the concave portions 2b to the total area of ​​the concave-convex layer 2 as viewed from the thickness direction of the laminated film 100 (as viewed from above in the illustrated example) is 50% or less.

[0011] Conventionally, when fabricating an optical element having a patterned low-refractive index layer, it is necessary to first form a coating film with a porous structure and then penetrate ink into portions of the porous structure to form the desired pattern. The portions of the porous structure that are not permeated with ink become the low-refractive index layer (portions), while the portions that are permeated with ink are formed as portions that do not function as low-refractive index portions. Therefore, the material in the portions that are permeated with ink (portions that do not function as low-refractive index portions) is essentially wasted as material for forming the low-refractive index portions. Furthermore, attempts to miniaturize the pattern shape of the low-refractive index portion (reducing the area of ​​the low-refractive index portion) increase the amount of ink used for permeation and also reduce the spacing between inks, which can lead to interference between adjacent patterns and result in defective pattern shapes.

[0012] In contrast, the surface protective film in the laminate film according to an embodiment of the present invention has through holes formed therein, which may correspond to recesses in the uneven layer. Furthermore, when the surface protective film is placed on the main surface of the substrate, exposed portions of the substrate are formed at positions corresponding to the through holes on the main surface of the substrate (hereinafter, sometimes referred to as "exposed portions"). During the manufacturing process of the laminate film, low refractive index portions are formed in the through holes (exposed portions). Since the low refractive index portions are typically significantly thinner than the surface protective film, the low refractive index portions constitute the recesses in the uneven layer. Thus, in the laminate film according to an embodiment of the present invention, the surface protective film functions as a mask for selectively forming low refractive index portions. In other words, to form patterned low refractive index portions, it is sufficient to form through holes in the surface protective film in a desired pattern and then coat the through holes with a material for forming the low refractive index portions. As a result, when the laminate film according to an embodiment of the present invention is used to manufacture an optical component, not only is the need for ink to be permeated to selectively form low refractive index portions, as in the prior art, unnecessary, but the amount of material used to form the low refractive index portions can also be reduced. Furthermore, the convex portions can be made not to function as low-refractive-index portions, and there is no need to fill the surface protection film with ink or the like (to prevent them from functioning as low-refractive-index portions). Furthermore, in the laminate film according to the embodiment of the present invention, as described above, patterning of the low-refractive-index portions does not involve ink penetration and is not affected by ink interference, etc., so defects in the pattern shape of the low-refractive-index portions can be suppressed. Therefore, by using the laminate film according to the embodiment of the present invention, defects in the pattern shape of the low-refractive-index portions can be suppressed, and optical components can be realized at low cost and with improved productivity.

[0013] In this specification, the laminate film as viewed in the thickness direction of the laminate film is sometimes simply referred to as a "plan view," and a view of the plan view is sometimes referred to as a "plan view." For example, FIG. 1B is a partial plan view of a laminate film 100 according to one embodiment of the present invention. In FIG. 1B, the area of ​​the concave-convex layer 2 in the plan view is the entire area of ​​the laminate film 100.

[0014] In the illustrated example (e.g., FIG. 1A), the uneven layer 2 is formed on one side (first main surface 10a) of the main surfaces of the substrate 10, but the uneven layer may also be formed on the second main surface 10b side, or the uneven layer may be formed on both the first main surface and the second main surface.

[0015] The ratio of the total area of ​​the recesses 2b to the total area of ​​the uneven layer 2 as viewed in the thickness direction of the laminated film 100 is preferably 40% or less, more preferably 30% or less, and even more preferably 25% or less. The lower limit of the ratio of the total area of ​​the recesses 2b to the total area of ​​the uneven layer 2 is, for example, more than 0%, and is preferably 1% or more, more preferably 3% or more, and even more preferably 5% or more.

[0016] In the illustrated example, the low refractive index portions 20 are arranged between the convex portions 2a of the uneven layer 2, and form the concave portions 2b. The low refractive index portions 20 are preferably arranged on the first main surface 10a of the substrate 10. "Arranged on the first main surface of the substrate" means that the low refractive index portions 20 are arranged in contact with the first main surface of the substrate.

[0017] The low refractive index portions are preferably formed in an island shape in plan view when viewed from the thickness direction of the laminate film. Forming the low refractive index portions in an island shape can contribute to further improving the light extraction efficiency of an optical component that can be fabricated from the laminate film according to an embodiment of the present invention. "Island shape" means that, in plan view, multiple low refractive index portions are not continuous but are arranged spaced apart. In a laminate film according to one embodiment of the present invention, multiple low refractive index portions are formed in an island shape by forming through holes patterned in an island shape in the surface protective film.

[0018] In a laminate film according to one embodiment of the present invention, the equivalent isocircular diameter of the low refractive index portion in plan view is preferably 1 μm or more and 500 μm or less. Having the equivalent isocircular diameter of the low refractive index portion in plan view within the above range has the advantage of providing a laminate film capable of realizing optical components having a finer pattern shape. The "equivalent isocircular diameter of the low refractive index portion in plan view" refers to the diameter of a circle when the shape of the recess constituting the low refractive index portion on the surface (plane) in plan view is assumed to be circular. The equivalent isocircular diameter of the low refractive index portion in plan view is more preferably 2 μm or more, even more preferably 5 μm or more, and particularly preferably 10 μm or more. Meanwhile, the equivalent isocircular diameter of the low refractive index portion in plan view is more preferably 300 μm or less, even more preferably 250 μm or less. When the shape of the recess in plan view is assumed to be elliptical, the equivalent isocircular diameter refers to the major axis of the ellipse. When the shape of the recess in plan view is assumed to be polygonal, the equivalent isocircular diameter refers to the diameter of the inscribed circle.

[0019] A-2. Overall structure of optical components An optical element according to an embodiment of the present invention includes a substrate and a plurality of low refractive index portions disposed on a major surface of the substrate. Optical element 101 shown in Fig. 2A includes a substrate 10 and a plurality of low refractive index portions 20 disposed on a major surface (first major surface 10a in Fig. 2A) of the substrate 10. The low refractive index portions have a porous structure. The ratio of the area of ​​the low refractive index portions to the total area of ​​the major surface of the substrate and the low refractive index portions when viewed in the thickness direction of the optical element is 50% or less.

[0020] Optical elements according to embodiments of the present invention may typically have a light distribution function. The light distribution function refers to, for example, a function in which a laminate film is disposed on a light guide layer, and a portion of the light from the light source is totally reflected by a low refractive index portion, partially blocking the light from exiting from one side of the light guide layer, thereby allowing a portion of the light to exit the light guide layer from a location where the low refractive index portion is not provided, thereby adjusting the light intensity and thereby changing the degree of light extraction depending on the position of the light guide layer from the light source. Achieving light distribution can contribute to uniforming the brightness of the light emitted from the light guide layer. As described above, in optical elements according to embodiments of the present invention, the low refractive index portion of the laminate film can be easily patterned, and finer patterns can be easily achieved. Therefore, according to the optical member of the present invention, defects in the pattern shape can be suppressed. Furthermore, according to the optical member of the present invention, the low refractive index portion can be favorably miniaturized, and therefore, highly efficient light distribution can be realized.

[0021] The optical member according to the embodiment of the present invention has a configuration in which the surface protection film is peeled off from the laminate film. That is, the optical member according to the embodiment of the present invention can be produced by peeling off the surface protection film, which serves as a mask for forming the low refractive index portion, from the laminate film. The substrate and the low refractive index portion in the optical member according to the embodiment of the present invention may correspond to the substrate and the low refractive index portion in the laminate film, respectively. In the optical member according to the embodiment of the present invention, the same configuration as the laminate film will be omitted as appropriate, and the description of the laminate film described below will be used.

[0022] Next, the configuration that the laminate film or optical member according to the embodiment of the present invention may have will be specifically described.

[0023] B. Base material The substrate (and consequently the laminate film and optical laminate) may have any suitable shape. The substrate may be, for example, long or sheet-like. In the illustrated example (e.g., FIG. 3A), the substrate 10 is long and can be wound into a roll. In this specification, "long" means an elongated shape in which the length is sufficiently longer than the width, and includes, for example, an elongated shape in which the length is 10 times or more, preferably 20 times or more, the width.

[0024] The substrate may be, for example, a resin film. Any appropriate resin material may be used as the material constituting the resin film. Specific examples of the resin material constituting the resin film, such as the main component, include transparent resins such as cycloolefin (COP) resins (e.g., polynorbornene), polyester resins (e.g., polyethylene terephthalate (PET)), polycarbonate (PC), (meth)acrylic resins, polyvinyl alcohol resins, polyamides, polyimides, polyethersulfones, polysulfones, polystyrenes, polyolefins, and acetate resins. Other examples include thermosetting resins or ultraviolet-curable resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone resins. The term "(meth)acrylic resin" refers to an acrylic resin and / or a methacrylic resin. Other examples include glassy polymers such as siloxane polymers. The resin film may be, for example, an extrusion molded product of the above-mentioned resin material or resin composition. The resin film materials may be used alone or in combination. The resin material constituting the resin film may further contain additives, such as antioxidants, ultraviolet absorbers, light stabilizers, nucleating agents, fillers, pigments, surfactants, and antistatic agents.

[0025] The substrate may have any appropriate thickness. The thickness of the substrate is, for example, 6 μm or more and 1 mm or less. The thickness of the substrate is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more. The thickness of the substrate may typically be 100 μm or less.

[0026] C. Uneven layer The uneven layer is disposed on the first main surface of the substrate. The uneven layer has convex portions and concave portions between the convex portions. The convex portions are formed by a surface protection film. The concave portions are formed by low refractive index portions disposed between the convex portions. In other words, the thickness of the surface protection film is greater than the thickness of the low refractive index portions.

[0027] The pattern shape of the uneven layer (substantially, the low refractive index portion) can be any appropriate pattern depending on the purpose. The pattern shape of the uneven layer can be controlled, for example, based on the shape, number, and position of the through holes in the surface protection film that serves as a mask. Specific examples of the pattern shape of the uneven layer include circular, elliptical, rectangular, and polygonal shapes as the shape of the recesses (low refractive index portions) in a planar view. Specific examples of the pattern shape of the uneven layer include an arrangement in which the recesses in a planar view are spaced approximately equally apart in the length direction and width direction between adjacent recesses.

[0028] The longitudinal and widthwise distances between adjacent recesses in the plane of the laminate film according to the embodiment of the present invention are preferably each independently 2 μm or more and 5000 μm or less. When the longitudinal distance and widthwise distance are within the above ranges, the pattern shape of the low refractive index portion in the laminate film according to the embodiment of the present invention can be made finer. The longitudinal distance and widthwise distance refer to the distance between the centers (area centers of gravity) of adjacent recesses. In one embodiment of the laminated film 100, the pattern shape of the uneven layer 2 is such that, when viewed in a plane, the shape of the recesses 2b (low refractive index sections 20) is circular, and the recesses 2b (low refractive index sections 20) are arranged such that the intervals between adjacent recesses 2b in the length direction and width direction are equal.

[0029] In a laminated film according to one embodiment, the recesses (specifically, the low refractive index portions constituting the recesses) are more preferably arranged in a lattice pattern with approximately equal intervals in plan view. In other words, the low refractive index portions are arranged at approximately equal intervals in the length direction and width direction on the first main surface of the substrate. In this case, the respective lengthwise intervals and widthwise intervals are approximately equal to each other. "Approximately equal intervals" is not limited to strictly the same intervals, and an interval within a range of ±5 μm is acceptable as approximately equal intervals. The same applies to "approximately equal."

[0030] C-1. Surface protection film The surface protection film in the laminate film according to the embodiment of the present invention is temporarily and removably attached to the substrate. That is, as described above, the surface protection film functions as a mask for selectively forming a low refractive index portion and can protect the surface (main surface) of the substrate until the optical component is put into use. The surface protection film 30 in the illustrated example (e.g., FIG. 1A) includes a film layer 31 and a pressure-sensitive adhesive layer 32. The pressure-sensitive adhesive layer 32 can be disposed on the substrate side of the film layer 31. The surface protection film 30 is temporarily and removably attached to the substrate 10 via the pressure-sensitive adhesive layer 32. In the laminate film according to the embodiment of the present invention, as described above, the surface protection film (substantially the film layer 31 and the pressure-sensitive adhesive layer 32) constitutes the convex portions 2a of the concave-convex layer 2. In the illustrated example, the longitudinal direction of the elongated surface protection film 30 and the longitudinal direction of the substrate 10 are substantially parallel. In one embodiment, the width of the elongated surface protection film 30 can be designed to be substantially the same as or larger than the width of the substrate 10. The surface protective film can be provided on one or both of the main surfaces (first and second main surfaces) of the substrate.

[0031] The film layer of the surface protection film may be made of any suitable resin film. Examples of materials for forming the resin film include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and copolymer resins thereof. Ester resins (particularly polyethylene terephthalate resins) are preferred.

[0032] The thickness of the film layer is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more. The upper limit of the thickness of the film layer can be, for example, 200 μm or less, preferably 150 μm or less, and more preferably 100 μm or less. Such a thickness has the advantage that deformation is unlikely to occur even when tension is applied during transportation and / or lamination.

[0033] As the name suggests, the adhesive layer is composed of an adhesive. Examples of adhesives include adhesive compositions that use an acrylic resin, a styrene resin, a silicone resin, or the like as a base resin, and that are blended with a crosslinking agent selected from an isocyanate compound, an epoxy compound, an aziridine compound, or the like, and a silane coupling agent. Acrylic adhesives are preferably used from the standpoints of chemical resistance, adhesion (for example, to prevent penetration of a solution during immersion, as described below), and flexibility to adherends.

[0034] The thickness of the pressure-sensitive adhesive layer in the laminate film according to one embodiment of the present invention is smaller than the thickness of the film layer. The thickness of the pressure-sensitive adhesive layer is, for example, 1 μm or more and 60 μm or less. The thickness of the pressure-sensitive adhesive layer is preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more. On the other hand, the thickness of the pressure-sensitive adhesive layer is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less. Within the above range, the adhesive strength of the pressure-sensitive adhesive layer can be maintained to an extent that temporary adhesion is possible, and the incorporation of air bubbles between the substrate and the film layer can be suppressed. Furthermore, within the above range, problems such as pressure-sensitive adhesive overflow can be suppressed.

[0035] C-2.Low refractive index section As described above, the low refractive index portion is disposed between the convex portions of the concave-convex layer. In the laminate film and optical member according to the embodiment of the present invention, a plurality of low refractive index portions may be disposed.

[0036] The refractive index of the low refractive index portion is lower than that of the substrate, for example. The refractive index of the low refractive index portion is, for example, 1.30 or less, with the lower limit exceeding 1.00. The refractive index of the low refractive index portion is preferably 1.13 to 1.28, more preferably 1.14 to 1.27, even more preferably 1.15 to 1.26, and particularly preferably 1.16 to 1.25. When the refractive index of the low refractive index portion is within this range, the substrate can have a low refractive index portion having a pattern shape on the first main surface side (more specifically, the exposed portion of the substrate through the through holes), and the light distribution function can be particularly well exhibited. Unless otherwise specified, the refractive index refers to a refractive index measured at a wavelength of 550 nm. The refractive index is a value measured, for example, by the method described in the Examples below.

[0037] The total light transmittance of the low refractive index portion is preferably 85% to 99%, more preferably 87% to 98%, and even more preferably 89% to 97%. By providing such a low refractive index portion on the first main surface side of the substrate (more specifically, on the exposed portion of the substrate through the through holes), it is possible to achieve, for example, excellent transparency for the entire laminate film. As a result, for example, when the laminate film is applied to various products, visibility can be ensured. The total light transmittance can be measured, for example, using a haze meter (for example, "HM-150" manufactured by Murakami Color Research Laboratory Co., Ltd.).

[0038] The haze of the low refractive index portion is preferably less than 5%, more preferably less than 3%. On the other hand, the haze may be, for example, 0.1% or more, or 0.2% or more. By providing such a low refractive index portion on the first main surface side of the substrate (more specifically, the exposed portion of the substrate through the through holes), for example, it is possible to achieve excellent transparency for the entire laminate film. The haze can be calculated, for example, from the value measured with the same haze meter as above using the following formula. Haze (%) = [Diffuse transmittance (%) / Total light transmittance (%)] x 100 (%)

[0039] The thickness of the low refractive index portion is, for example, 0.1 μm or more, preferably 0.3 μm or more, more preferably 1.0 μm or more, even more preferably 1.2 μm or more, particularly preferably 1.5 μm or more, and particularly preferably 1.8 μm or more. The thickness of the low refractive index portion may be, for example, 2.2 μm or more, or, for example, 2.5 μm or more, or, for example, 2.8 μm or more. On the other hand, the thickness of the low refractive index portion may be, for example, 10 μm or less, or, for example, 8 μm or less, or, for example, 6 μm or less, or, for example, 4 μm or less. When the thickness of the low refractive index portion is within this range, the pattern shape of the low refractive index portion can be made more precise. Furthermore, when the thickness of the low refractive index portion is within this range, the productivity of producing an optical element from the laminate film according to this embodiment of the present invention can be further improved. Furthermore, when the thickness of the low refractive index portion is within this range, the optical element according to this embodiment of the present invention can particularly effectively exhibit light distribution and light intensity adjustment functions.

[0040] The thickness of the low refractive index portion of the laminate film according to an embodiment of the present invention is smaller than the thickness of the surface protective film. Furthermore, the thickness of the low refractive index portion is preferably smaller than the thickness of the film layer of the surface protective film. Furthermore, the thickness of the low refractive index portion is preferably smaller than the thickness of the pressure-sensitive adhesive layer of the surface protective film. When the thickness of the low refractive index portion satisfies the above, the pattern shape of the low refractive index portion can be made more precise, which can further improve the productivity when producing an optical element from the laminate film. Furthermore, when the thickness of the low refractive index portion is within this range, the optical element according to an embodiment of the present invention can particularly effectively exhibit the light distribution function and the light intensity adjustment function.

[0041] In the laminate film according to the embodiment of the present invention, the ratio of the thickness of the film layer to the thickness of the low refractive index layer is preferably within the range of 1:1 to 2000:1. Within this range, the laminate film and the optical component can exhibit more pronounced effects even when the thickness of the low refractive index portion in the laminate film and the optical component is made significantly smaller than the thickness of the film layer. The ratio of the thickness of the film layer to the thickness of the low refractive index layer in the laminate film is more preferably within the range of 1:1 to 1000:1, even more preferably 1:1 to 500:1, even more preferably 1:1 to 100:1, and particularly preferably 1:1 to 30:1.

[0042] In the laminate film according to the embodiment of the present invention, the ratio of the thickness of the pressure-sensitive adhesive layer to the thickness of the low refractive index layer is preferably within the range of 0.1:1 to 600:1. Within this ratio range, even when the thickness of the low refractive index portion in the laminate film and optical component is made sufficiently smaller than the thickness of the pressure-sensitive adhesive layer, the effects of the laminate film and optical component can be more significantly exhibited. The ratio of the thickness of the pressure-sensitive adhesive layer to the thickness of the low refractive index layer in the laminate film is more preferably within the range of 0.1:1 to 300:1, even more preferably 0.1:1 to 100:1, even more preferably 0.1:1 to 50:1, and particularly preferably 0.1:1 to 10:1.

[0043] The low refractive index portion has a porous structure. Any appropriate configuration can be adopted for the low refractive index portion as long as it can achieve the desired characteristics. As a material for forming the low refractive index portion (hereinafter, sometimes referred to as a "material for forming the low refractive index portion"), for example, materials described in International Publication No. 2004 / 113966, Japanese Patent Application Laid-Open No. 2013-254183, and Japanese Patent Application Laid-Open No. 2012-189802 can be adopted.

[0044] Representative examples of materials for forming low refractive index portions include silicon compounds. Examples of silicon compounds include silica-based compounds; hydrolyzable silanes and their partial hydrolysates and dehydration condensates; silicon compounds containing silanol groups; and activated silica obtained by contacting silicate with acid or ion exchange resin. Examples of materials for forming low refractive index portions include organic polymers; polymerizable monomers (e.g., (meth)acrylic monomers and styrene-based monomers); and curable resins (e.g., (meth)acrylic resins, fluorine-containing resins, and urethane resins). These materials may be used alone or in combination of two or more.

[0045] In one embodiment, the low refractive index portion may contain spaces such as holes and gaps therein. In this case, the porosity of the low refractive index portion is preferably 20 to 60 volume %, more preferably 25 to 55 volume %, even more preferably 30 to 50 volume %, and particularly preferably 35 to 45 volume %. Such a porosity allows the refractive index of the low refractive index portion to be within an appropriate range and ensures strength. Here, the porosity is a value calculated from the refractive index measured with an ellipsometer using the Lorentz-Lorenz formula.

[0046] The size of the pores that can be contained in the low refractive index portion can be adjusted to a desired size depending on the purpose and application. The size of the pores that can be contained in the low refractive index portion 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 pores that can be contained in the low refractive index portion is, for example, 500 nm or less, preferably 200 nm or less, and more preferably 100 nm or less. Note that the size of the pores refers to the diameter of the major axis of the pores, out of the diameter of the major axis and the diameter of the minor axis.

[0047] The pore size can be quantified by the BET test method. In one embodiment, 0.1 g of a measurement sample (e.g., a fabricated low refractive index portion) is placed in the capillary of a specific surface area measurement device (e.g., Micromeritics' "ASAP2020"), and then the sample is dried under reduced pressure at room temperature for 24 hours to remove gases contained in the measurement sample. Then, nitrogen gas is adsorbed onto the measurement sample, and an adsorption isotherm is drawn to determine the pore distribution. This allows the pore size to be evaluated.

[0048] Examples of the low refractive index portion having an internal space include a porous layer made of a porous body and / or a layer at least partially including an air layer. That is, the low refractive index portion having an internal space includes at least one of the porous layer and the air layer.

[0049] The low refractive index portion typically includes aerogel and / or particles (for example, hollow fine particles and / or porous particles). The low refractive index portion is preferably a nanoporous layer (specifically, 90% or more of the pores have a diameter of 1×10 -1 nm~1×10 3 The porous layer may be in the range of 100 nm.

[0050] Any appropriate particles may be used as the particles. The particles are typically made of a silica-based compound. Examples of particle shapes include spherical, plate-like, needle-like, string-like, and bunch-of-grapes shapes. Examples of string-like particles include particles in which a plurality of spherical, plate-like, or needle-like particles are strung together like beads, short fiber-like particles (e.g., short fiber-like particles described in JP 2001-188104 A), and combinations thereof. The string-like particles may be linear or branched. Examples of bunch-of-grapes-like particles include particles in which a plurality of spherical, plate-like, and needle-like particles are aggregated to form a bunch of grapes. The particle shape can be confirmed, for example, by observation using a transmission electron microscope.

[0051] An example of the low refractive index portion is a structure composed of one or more types of structural units that form a fine void structure, and these structural units are bonded to each other (for example, chemically bonded via catalytic action). Examples of the shape of the structural units include particulate, fibrous, rod-like, and flat plate-like. The structural units may have only one shape, or may have two or more shapes in combination.

[0052] A specific example of the low refractive index portion is a porous layer composed of a porous body in which particles having micropores (hereinafter referred to as micropore particles) are chemically bonded to each other. Such a porous layer can be obtained, for example, by chemically bonding the micropore particles to each other. The shape of the micropore particles is not particularly limited and may be, for example, spherical or other shapes. The micropore particles may also be, for example, sol-gel beaded particles, nanoparticles (e.g., hollow nanosilica nanoballoon particles), nanofibers, etc. Representative micropore particles 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 alone or in combination of two or more. In one embodiment, the micropore particles are, for example, micropore particles of a silicon compound, and the porous body is, for example, a silicone porous body. The micropore particles of a silicon compound include, for example, a pulverized gel silica compound.

[0053] Another example of the low refractive index portion is a layer containing a fibrous material such as nanofibers, in which spaces are formed by the entanglement of the fibrous material. Further examples of the low refractive index portion include a layer formed using hollow nanoparticles or nanoclay, and a layer formed using hollow nanoballoons or magnesium fluoride. The low refractive index portion may be composed of a single constituent material, or may be composed of multiple constituent materials. The low refractive index portion may be composed of a single form of the above examples, or may be composed of multiple forms of the above examples.

[0054] The porous layer may have, for example, an open-cell structure, in which the pores are interconnected. An open-cell structure refers to a porous body (e.g., a porous silicone body) in which the pores are interconnected three-dimensionally, and can also be described as a state in which the pore spaces are interconnected. The open-cell structure of the porous layer can enhance porosity. It is difficult to form an open-cell structure using closed-cell particles with individual pore structures, such as hollow particles (e.g., hollow silica). However, when using silica sol particles (a pulverized product of a gel-like silicon compound that forms a sol), the silica sol particles can have a three-dimensional dendritic structure. The dendritic particles can settle and deposit in a coating film (a coating film of a sol containing a pulverized product of a gel-like silicon compound) to easily form an open-cell structure. The porous layer preferably has a monolithic structure in which the open-cell structure includes a distribution of multiple pores. The monolithic structure refers to, for example, a hierarchical structure including a structure with nano-sized pores and an open-cell structure in which nano-sized pores are aggregated. The monolithic structure, for example, can provide membrane strength through fine pores while providing high porosity through a coarse open-cell structure, thereby achieving both membrane strength and high porosity.

[0055] For example, the monolith structure can be formed by controlling the pore distribution of the resulting void structure in a gel (gel silicon compound) prior to pulverization into silica sol particles. Furthermore, for example, when pulverizing a gel silicon compound, the monolith structure can be formed by controlling the particle size distribution of the pulverized silica sol particles to a predetermined size. The particle size distribution can be measured, for example, using a particle size distribution evaluation device such as a dynamic light scattering method or a laser diffraction method, or an electron microscope such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

[0056] As described above, the porous layer may contain pulverized gel compounds such as gel silicon compounds, and the pulverized particles are chemically bonded to each other. The chemical bonds are not particularly limited, and examples thereof include cross-linking, covalent bonding, and hydrogen bonding. The volume average particle size of the pulverized particles 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. Meanwhile, the volume average particle size of the pulverized particles in the porous layer is, for example, 2.00 μm or less, preferably 1.50 μm or less, and more preferably 1.00 μm or less. The volume average particle size is an index of the particle size variation of the pulverized particles and is determined by particle size distribution measurement.

[0057] The low refractive index portion may contain silicon atoms. For example, the silicon atoms contained in the low refractive index portion are preferably siloxane-bonded. Of all silicon atoms contained in the low refractive index portion, the proportion of unbonded silicon atoms (specifically, residual silanols) is, for example, less than 50%, preferably 30% or less, and more preferably 15% or less.

[0058] In one embodiment, the material for forming the low refractive index portion may be a coating liquid in which the above-mentioned material is dispersed in a dispersion medium. The dispersion medium can adjust the viscosity and other properties of the coating liquid to a suitable range. As a result, the coating properties when forming the low refractive index portion can be improved. The dispersion medium may be a single solvent or a mixed solvent containing multiple solvents.

[0059] Examples of dispersion media include alcohols such as ethanol, isopropyl alcohol, butanol, t-butanol, isobutyl alcohol, and 2-methoxyethanol (methyl cellosolve); esters such as ethyl acetate and butyl acetate; ethers such as diisopropyl ether and propylene glycol monomethyl ether; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and aromatic hydrocarbons such as toluene. These dispersion media can be used alone or in combination. Among these dispersion media, alcohols are more preferred, and isobutyl alcohol is even more preferred. The mass ratio of the dispersion medium to the total amount of the low refractive index portion forming material is, for example, 5 mass% or more, preferably 30 mass% or more, more preferably 40 mass% or more, and is, for example, 100 mass% or less, preferably 95 mass% or less, more preferably 60 mass% or less. If the content ratio of the dispersion medium is within the above range, the viscosity of the low refractive index portion forming material can be stably adjusted to a range suitable for spray coating.

[0060] In one embodiment, the coating film (a coating film of a sol containing a pulverized product of a gel-like silicon compound) can be formed using a coating liquid containing microporous particles, and the microporous particles can be chemically bonded to each other by heating (including drying) this coating liquid. The coating liquid containing microporous particles is, for example, a suspension. For example, a catalyst (crosslinking reaction accelerator) that accelerates crosslinking between the microporous particles (for example, a dehydration condensation reaction of residual silanol groups that may be contained in the microporous particles) and / or a substance (catalyst generator) that generates a catalyst (crosslinking reaction accelerator) may be added to the coating liquid. Examples of catalysts include photoactivated catalysts and thermally activated catalysts. Examples of catalyst-generating substances (catalyst generators) include photocatalyst generators and thermal catalyst generators. Examples of photocatalyst generators include photobase generators (catalysts that generate a basic catalyst upon light irradiation) and photoacid generators (substances that generate an acidic catalyst upon light irradiation). For example, the microporous particles may be a pulverized product of a gel-like compound (preferably a gel-like silicon compound), and the low refractive index portion may have a porous structure composed of a porous body (preferably a silicone porous body) containing the pulverized product of the gel-like compound. Such microporous particles may have a state in which the three-dimensional structure of the gel-like compound before pulverization is dispersed in the three-dimensional basic structure. Using such microporous particles, a structure based on the three-dimensional basic structure may be formed. Specifically, a new structure different from the three-dimensional structure of the gel-like compound may be formed. Thus, the finally obtained low refractive index portion (porous structure) may have a refractive index as low as, for example, an air layer. Furthermore, by chemically bonding the microporous particles to each other, the three-dimensional basic structure may be fixed, and the finally obtained low refractive index portion (porous structure) may have sufficient strength. Details of the specific configuration and formation method of the low refractive index portion (porous structure) are described, for example, in International Publication No. 2019 / 151073. The disclosure of this publication is incorporated herein by reference.

[0061] The coating thickness of the coating liquid can be set according to the thickness desired for the low refractive index portion. The heating temperature of the coating film (coating liquid) is, for example, 20°C or higher, preferably 50°C or higher. On the other hand, the heating temperature of the coating film (coating liquid) is, for example, 200°C or lower, preferably 150°C or lower. The heating time of the coating film (coating liquid) is, for example, 10 seconds or longer. On the other hand, the heating time of the coating film (coating liquid) is, for example, 24 hours or shorter, preferably 1 hour or shorter, more preferably 30 minutes or shorter, and even more preferably 10 minutes or shorter.

[0062] A coating film that forms a void structure, which is a precursor of a porous layer (void layer), is formed on a substrate. The following describes the case where the particles are pulverized gel compounds. However, a coating film can be formed in the same way when the particles are other than pulverized gel compounds. The reason why a void structure suitable for the coating film is formed when the particles are pulverized gel compounds is presumed to be, for example, as follows. However, this presumption does not limit the method for forming the low refractive index portion.

[0063] Since the above-mentioned particles (porous particles) are made by pulverizing gel silicon compound, the three-dimensional structure of the gel silicon compound before pulverization is dispersed in the three-dimensional basic structure.For example, by spraying the crushed material of gel silicon compound onto a substrate, the precursor of the porous structure based on the three-dimensional basic structure is formed.In other words, according to the above-mentioned method, a new porous structure (three-dimensional basic structure) is formed by spraying the crushed material, which is different from the three-dimensional structure of the gel silicon compound.Therefore, in the low refractive index part that is finally obtained, for example, it can realize a low refractive index that functions as the same as an air layer.

[0064] D.Laminated Film Manufacturing Method The laminate film according to the embodiment of the present invention can be produced, for example, by disposing a surface protection film having through holes on a first main surface of a substrate, and applying a low refractive index portion-forming material to the exposed portion of the substrate exposed by the through holes to form a low refractive index portion. More specifically, the laminate film according to the embodiment of the present invention can be produced, for example, as follows.

[0065] First, a surface protection film is prepared. In the laminate film manufacturing method according to an embodiment of the present invention, the surface protection film can be used as a mask for forming a pattern of low refractive index portions. Therefore, the surface protection film preferably has through holes formed in a desired pattern. Low refractive index portions can be formed in the exposed portions of the through holes. In the illustrated example (e.g., FIG. 3B), the positions at which the through holes 33 are provided correspond to the positions at which the low refractive index portions are desired to be formed, and as a result, correspond to the positions of the recesses 2b in the uneven layer 2.

[0066] Next, the surface protection film 30 is disposed on the substrate 10 (for example, the first main surface 10a) (this step may be referred to as a disposing step). The surface protection film 30 is typically releasably attached to the substrate 10 via the pressure-sensitive adhesive layer 32, as described above.

[0067] In one embodiment, as shown in Fig. 3A, a long surface protection film 30 having a plurality of through holes 33 arranged in a predetermined pattern is laminated by roll-to-roll onto a long substrate 10. When the surface protection film having through holes is placed on the substrate, exposed portions 11 are formed as shown in Fig. 3B.

[0068] Next, a low refractive index portion is formed in the through-hole (exposed surface) (sometimes referred to as a low refractive index portion forming step). In the low refractive index portion forming step, for example, a low refractive index portion forming material is applied to the exposed portion (see FIGS. 3B and 3C). Details of the low refractive index portion forming material are as described in Section C-2 above.

[0069] Specifically, the low refractive index portion can be formed, for example, by applying a liquid low refractive index portion-forming material (coating liquid) to the exposed portion of the substrate via a surface protection film having through holes disposed on the main surface of the substrate. More specifically, the low refractive index portion can be formed by heating the formed coating film. In other words, the low refractive index portion can be composed of a dried product, semi-cured product, or cured product of a coating film made from the low refractive index portion-forming material or coating liquid.

[0070] Any appropriate method may be employed for applying the low refractive index portion-forming material. Specific examples of the application method include application methods such as spraying (spray coating), roll coating, and spin coating; and printing methods such as inkjet printing and screen printing. Any appropriate application device may be employed for application. Specific examples of the application device include a spray coater, a roll coater, a spin coater, a dispenser, an inkjet coater, and a screen printer.

[0071] In the low refractive index portion forming step, the low refractive index portion forming material (coating liquid) is preferably applied by spraying (also simply referred to as spraying). The laminate film according to an embodiment of the present invention uses a surface protection film having through holes that function as a mask, so spraying can further reduce the amount of low refractive index portion forming material used. Furthermore, the surface protection film does not need to be filled with paint such as ink. As a result, by using the laminate film according to an embodiment of the present invention, optical components can be produced at low cost and with high productivity.

[0072] A specific description will be given of the case where spraying is performed in the low refractive index portion forming step. The above-mentioned low refractive index portion forming material can be suitably employed for spraying. In spraying, the above-mentioned low refractive index portion forming material is sprayed onto a substrate on which a surface protective film is disposed as a mask, and a coating film is formed on exposed portions of the substrate. The coating film may be formed on exposed portions of the substrate by spraying, for example, while conveying the substrate on which the surface protective film is disposed with a roll.

[0073] In the case of spraying, the low refractive index portion forming material is preferably sprayed onto the substrate so that the rate of change in solid content concentration satisfies the following formula (1). 1.3≦Solid content change rate≦60 (1)

[0074] Preferably, the viscosity [mPa·s] of the coating film 10 seconds after spraying satisfies the following formula (2): 0.0549e 1.2xViscosity of coating film 10 seconds after spraying: ≦0.0549e 3.3x ···(2) (In formula (2), e represents the Napier's number; x represents the solids concentration in the coating film 10 seconds after spraying.)

[0075] The viscosity of the coating film 10 seconds after spraying is specifically 3 mPa·s or more, preferably 5 mPa·s or more, more preferably 8 mPa·s or more, even more preferably 10 mPa·s or more, and particularly preferably 15 mPa·s or more, and for example, 500 mPa·s or less, preferably 300 mPa·s or less, more preferably 200 mPa·s or less, and particularly preferably 100 mPa·s or less. If the viscosity of the coating film is within the above range, the transparency and thickness precision of the low refractive index portion can be further improved.

[0076] The viscosity of the low refractive index portion forming material before spraying is, for example, 0.5 mPa·s or more, preferably 1.0 mPa·s or more, and for example, 300 mPa·s or less, preferably 100 mPa·s or less. These viscosities can be calculated using a rheometer manufactured by Anton-Paar.

[0077] In the spraying, the distance (coating distance) between the spray head that sprays the low refractive index portion forming material and the substrate can be adjusted as appropriate. When the distance between the spray head and the substrate increases, the rate of change in the solid content concentration increases, and when the distance between the spray head and the substrate decreases, the rate of change in the solid content concentration decreases. The distance (coating distance) between the spray head and the substrate is, for example, 30 mm or more, preferably 50 mm or more, and, for example, 300 mm or less, preferably 200 mm or less.

[0078] In one embodiment, the spray head sprays the low refractive index portion forming material while moving in a plane direction including the exposed surface of the substrate. The atomization pressure of the spray is, for example, 100 kPa to 1000 kPa, the application rate of the spray is, for example, 0.1 mL / min to 20 mL / min, and the moving speed of the spray head during spraying is, for example, 10 mm / sec to 1000 mm / sec.

[0079] In this way, a laminated film having a concave-convex layer on a substrate can be produced. The laminated film manufacturing method according to an embodiment of the present invention may include the step of forming the through holes (through hole forming step), the positioning step, and the low refractive index portion forming step. However, the laminated film manufacturing method is not limited to the above-described method and the above-described order.

[0080] In one embodiment, the formation of the low refractive index portion further includes a step of heating and drying the coating film on the substrate. The heating temperature is, for example, 60°C or higher, preferably 70°C or higher, and more preferably 80°C or higher, and for example, 200°C or lower, preferably 120°C or lower, and more preferably 100°C or lower. The heating time is not particularly limited as long as the coating film can be sufficiently dried. In one embodiment, a crosslinking reaction occurs between the particles in the coating film during this process, thereby fixing the three-dimensional basic structure. As a result, the resulting low refractive index portion can maintain sufficient strength and flexibility despite having a void structure.

[0081] E. Optical Members and Methods for Manufacturing Optical Members An optical element according to an embodiment of the present invention includes a substrate and a plurality of low refractive index portions disposed on a main surface of the substrate. An optical element 101 in the illustrated example (e.g., FIG. 2A) includes a substrate 10 and a plurality of low refractive index portions 20 disposed on a first main surface 10a of the substrate 10. The low refractive index portions 20 have a porous structure. Furthermore, the ratio of the total area of ​​the low refractive index portions 20 to the total area of ​​the main surface of the substrate 10 and the low refractive index portions 20 when viewed in the thickness direction of the optical element 101 is 50% or less.

[0082] As described above, the optical member is a member in which the surface protection film is peeled off from the laminate film described above, and therefore may have a patterned low refractive index portion. The substrate and low refractive index portion in the optical member according to the embodiment of the present invention are the same as those described in Sections B and C-2 above.

[0083] The method for producing an optical member includes a step of peeling off the surface protective film (also referred to as a peeling step) after producing a laminate film in the same manner as the method for producing a laminate film described in Section D above (see FIG. 4). That is, a method for producing an optical member according to one embodiment of the present invention may include the through-hole forming step, the arranging step, the low refractive index portion forming step, and the peeling step. The long laminate (ultimately an optical member) obtained by the above production method may be cut to any appropriate size to form sheet-like optical members of appropriate sizes. [Example]

[0084] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0085] (1) Refractive index The low refractive index portion used in the examples and comparative examples was formed on an acrylic film. The resulting laminate of the acrylic film and the low refractive index portion was cut to a size of 25 mm x 50 mm. The cut laminate was attached to the surface of a glass plate (thickness: 3 mm) via an adhesive. The center of the back surface of the glass plate (diameter: approximately 20 mm) was filled in with a black oil-based pen to create a sample that did not reflect light from the back surface of the glass plate. The sample was set in an ellipsometer (JA Woollam Japan: VASE), and the refractive index was measured at a wavelength of 550 nm and an incident angle of 50 to 80 degrees.

[0086] (2) Thickness The thickness was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000").

[0087] (3) Dot diameter, pitch, number of patterns, and area ratio of the low refractive index portion The dot diameter and pitch of the low refractive index portion were confirmed by observing the planar shape of the recesses of the uneven layer in the laminated film using a laser microscope (model number VK-X1000) manufactured by KEYENCE Corporation and processing the image. The dot diameter of the low refractive index portion is the diameter a of a circle (ie, the equivalent diameter of an ellipse with an equal circumference) when the shape of the recess in plan view is a circle, as shown in FIG. The pitch refers to the distance between the centers of adjacent recesses in the length direction (or width direction) in a plan view, as shown in Fig. 5. The distance between the centers of adjacent recesses in the length direction is referred to as the length direction pitch px, and the distance between the centers of adjacent recesses in the width direction is referred to as the width direction pitch py. When the length direction pitch and the width direction pitch are equal, they are simply referred to as pitches. The number of patterns in the low refractive index area is 1cm 2 The number of patterns per dot is calculated based on the dot diameter and pitch. The area ratio of the low refractive index portion is calculated by observing the laminated film with a laser microscope, calculating the total area of ​​the uneven layer and the total area of ​​the recesses in a planar view based on the image processed, and then calculating the ratio of the total area of ​​the recesses to the total area of ​​the uneven layer.

[0088] [Production Example 1] Preparation of low refractive index portion forming material (coating liquid) (1) Gelation of silicon compounds Mixture A was prepared by dissolving 0.95 g of methyltrimethoxysilane (MTMS), a precursor of a silicon compound, in 2.2 g of dimethyl sulfoxide (DMSO). 0.5 g of a 0.01 mol / L aqueous solution of oxalic acid was added to this mixture A, and the mixture was stirred at room temperature for 30 minutes to hydrolyze the MTMS, producing mixture B containing tris(hydroxy)methylsilane. To 5.5 g of DMSO, 0.38 g of 28 wt % aqueous ammonia and 0.2 g of pure water were added, and then the above mixed solution B was further added and stirred at room temperature for 15 minutes to gel the tris(hydroxy)methylsilane, thereby obtaining mixed solution C containing a gel-like silicon compound. (2) Aging treatment The mixed solution C containing the gel-like silicon compound prepared as above was incubated as is at 40° C. for 20 hours for aging treatment. (3) Crushing Next, the gel-like silicon compound aged as described above was crushed into granules of several mm to several cm in size using a spatula. Next, 40 g of isopropyl alcohol (IPA) was added to mixed solution C, and after light stirring, the mixture was left to stand at room temperature for 6 hours, and the solvent and catalyst in the gel were decanted. The same decantation process was repeated three times to replace the solvent, yielding mixed solution D. The gel-like silicon compound in mixed solution D was then crushed (high-pressure media-less crushing). The crushing process (high-pressure media-less crushing) was carried out using a homogenizer (manufactured by SMT Corporation, product name "UH-50"), with 1.85 g of the gel-like compound in mixed solution D and 1.15 g of IPA weighed into a 5 cc screw bottle, and crushed for 2 minutes at 50 W and 20 kHz. This grinding process pulverized the gel-like silicon compound in the mixed solution D, turning the mixed solution D into a pulverized sol solution E. The volume average particle size, which indicates the particle size variation of the pulverized material contained in sol solution E, was measured using a dynamic light scattering Nanotrac particle size analyzer (manufactured by Nikkiso Co., Ltd., UPA-EX150 model) and found to be 0.50 to 0.70 μm. Furthermore, 0.015 g of a 1.5 wt% MEK (methyl ethyl ketone) solution of a photobase generator (Wako Pure Chemical Industries, Ltd., product name: WPBG266) and 0.005 g of a 5 wt% MEK solution of a bis-crosslinking accelerator ((trimethoxysilyl)hexane) were added to 0.75 g of sol solution E to obtain a coating solution 1 for forming a low refractive index portion. The refractive index of the low refractive index portion formed using this coating solution was 1.2.

[0089] [Example 1] Base film 1 was prepared as the substrate, protective film 1 was prepared as the surface protective film, and the coating liquid of Production Example 1 was prepared as the low refractive index portion forming material. Through holes were formed in the surface protection film so as to have a predetermined pattern shape with the dot diameters shown in Table 1 and with equal pitches in the length direction and width direction. Subsequently, the surface protection film with the through holes formed therein was attached to the substrate via the pressure-sensitive adhesive layer of the surface protection film. Next, a coating film of the low refractive index portion forming material was formed by spray coating the coating liquid of the low refractive index portion forming material of Production Example 1 into the through holes of the surface protective film. Specifically, the spray coating was performed as follows. The low refractive index portion forming material and a substrate (hereinafter referred to as a laminate) to which a surface protective film having through holes was attached were set in a spray coater (manufactured by Apeiros, product name API-240 series). The distance (coating distance) between the spray head (nozzle) and the substrate (exposed portion) in the laminate was 125 mm. Next, the low refractive index portion forming material was spray coated onto the exposed portion of the substrate of the laminate under coating conditions of an atomization pressure of 100 kPa and a coating amount of 7 mL / min, to form a coating film on the exposed portion of the substrate. Next, the coating film on the exposed portion of the substrate in the laminate was dried at 90°C for 10 minutes, and then dried at 70°C for 24 hours. This resulted in a laminate film provided on the substrate with a concave-convex layer having a surface protection film constituting the convex portions and low refractive index portions constituting the concave portions. The low refractive index portions had a thickness of 2.0 μm. The obtained laminate film was subjected to the measurements and evaluations (1) to (3) above.

[0090] [Examples 2 to 4] Laminated films were produced in the same manner as in Example 1, except that the dot diameter and pitch of the pattern shape of the through holes in the surface protective film were changed as shown in Table 1. The thickness of the low refractive index portion in each example is as shown in Table 1. The obtained laminated films were subjected to the same evaluations as in Example 1.

[0091] [Comparative Example 1] A base film 1 was prepared as the substrate, and the coating liquid of the above-mentioned Manufacturing Example 1 was prepared as the material for forming the low refractive index portion. The material for forming the low refractive index portion was applied to the entire first main surface of the substrate, thereby producing a coating film (layer) made of the material for forming the low refractive index portion. Next, a paint (curable resin composition: urethane-based photocurable resin (Daicel Allnex Corporation product name KRM8904)) that penetrates into the material for forming the low refractive index portion was injected into the paint inlet of the inkjet device, and the paint was ejected by inkjet method onto the coating film of the material for forming the low refractive index portion on the substrate so that the ejected droplets of paint had the dot diameter and pitch listed in Table 1, thereby forming a coating film of the paint with a predetermined interval (pattern) and producing a laminate. Subsequently, the laminate was heated at 100°C for 5 minutes to carry out heat aging. This allowed the paint to penetrate into the low refractive index layer (porous layer). The paint was filled into a portion of the low refractive index layer (porous layer), yielding a laminate film with a patterned low refractive index portion. Note that no surface protective film was used in Comparative Example 1. The thickness of the low refractive index portion is as shown in Table 1. The obtained laminate film was subjected to the same evaluation as in Example 1.

[0092] The materials shown in Table 1 are as follows: (base material) Base film 1: Glass substrate (acrylic film (manufactured by Corning, product name EAGLE XG. Material: alkali-free glass, thickness: 0.7 mm.) (Surface protection film) Protective film 1: Surface protective film (product name E-MASK, manufactured by Nitto Denko Corporation).

[0093] [Table 1]

[0094] As is clear from Table 1, according to the examples of the present invention, a laminated film can be obtained that can suppress defects in the pattern shape and realize optical members that can improve productivity. [Industrial Applicability]

[0095] The laminated film according to the embodiment of the present invention can be suitably used to produce an optical element, and the optical element according to the embodiment of the present invention can be suitably used as an optical element having a light distribution function. [Explanation of symbols]

[0096] 10 Base material 11 Exposed part 10a First principal surface 10b Second principal surface 2 Uneven layer 2a Convex part 2b Recess 20 Low refractive index section 30 Surface protection film 31 film layers 32 adhesive layer 33 Through hole 100 Laminated Film 101 Optical components

Claims

1. a substrate having a first major surface and a second major surface opposite the first major surface; a relief layer disposed on the first major surface; A laminated film comprising: the concave-convex layer has convex portions formed of a surface protection film and concave portions formed of low refractive index portions disposed between the convex portions, the low refractive index portion has a porous structure, the ratio of the total area of ​​the recesses to the total area of ​​the uneven layer as viewed in the thickness direction of the laminated film is 50% or less; Laminated film.

2. The laminated film according to claim 1 , wherein the low refractive index portion is disposed on a first main surface of the substrate.

3. The laminated film according to claim 2 , wherein the low refractive index portions are formed in an island shape in a plan view when viewed from the thickness direction.

4. The laminated film according to claim 3 , wherein the low refractive index portion has an equivalent diameter of an equal-circumference ellipse in a plan view of 1 μm or more and 500 μm or less.

5. the surface protection film comprises a film layer and a pressure-sensitive adhesive layer disposed on the substrate side of the film layer, The laminated film according to claim 1 , wherein the thickness of the low refractive index portion is smaller than the thickness of the film layer.

6. The laminated film according to claim 5 , wherein the low refractive index portion has a thickness smaller than a thickness of the pressure-sensitive adhesive layer.

7. A method for producing the laminated film according to any one of claims 1 to 6, a through-hole forming step of forming a through-hole in the surface protective film; a disposing step of disposing a surface protection film having the through holes formed therein on the substrate; and a low refractive index portion forming step of forming a low refractive index portion by applying a low refractive index portion forming material to the exposed portion of the base material due to the through hole. A method for manufacturing a laminated film.

8. The low refractive index portion forming step includes applying the low refractive index portion forming material by spraying. The method for producing the laminated film according to claim 7.

9. An optical member comprising a substrate and a plurality of low refractive index portions disposed on a main surface of the substrate, the low refractive index portion has a porous structure, a ratio of an area of ​​the low refractive index portion to a total area of ​​the main surface of the substrate and the low refractive index portion as viewed in the thickness direction of the optical member is 50% or less; Optical components.

10. The optical member according to claim 9 , wherein the low refractive index portions are formed in an island shape in a plan view when viewed in the thickness direction.

11. The optical member according to claim 10 , wherein the low refractive index portion has an equivalent diameter of an equal-circumference ellipsoid in a plan view of 1 μm or more and 500 μm or less.

12. A method for producing an optical member according to any one of claims 9 to 11, comprising: a through-hole forming step of forming a through-hole in a surface protection film that protects the substrate; a disposing step of disposing a surface protection film having the through holes formed therein on the substrate; a low refractive index portion forming step of forming a low refractive index portion by applying a low refractive index portion forming material to the exposed portion of the base material due to the through hole; a peeling step of peeling off the surface protective film after the low refractive index portion forming step, A method for manufacturing an optical member.

13. The low refractive index portion forming step includes applying the low refractive index portion forming material by spraying. The method for producing an optical member according to claim 12 .

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