Optical member, method for producing same, and optical element

Abstract

This optical member has a first layer (10) with a porous structure, the first layer (10) includes a first area (12) with the porous structure and a second area (14) in which the pores of the porous structure are filled with a resin composition, the second area (14) includes a plurality of discretely arranged island-like areas, and when the area ratio of the first layer (10) occupied by the second area (14) is denoted by P% and the haze value of the first layer is denoted by H%, H / P is less than 0.20.

Description

Optical member, manufacturing method thereof, and optical element

[0001] The present invention relates to an optical member, a method for manufacturing the same, and an optical element.

[0002] As a method for extracting light from a light guide layer, a method using a light extraction layer having two regions with different refractive indices is known (for example, Patent Document 1).

[0003] According to Patent Document 1, for example, a pressure-sensitive adhesive layer is formed on a porous layer, and laser light is irradiated onto the pressure-sensitive adhesive layer in a predetermined pattern, and the voids in the porous layer are filled with the molten pressure-sensitive adhesive, thereby forming a light extraction layer in which low refractive index regions with remaining voids and high refractive index regions with the voids filled with the pressure-sensitive adhesive are arranged in a predetermined pattern.

[0004] The entire disclosure of Patent Document 1 is incorporated herein by reference. In this specification, the light extraction layer in Patent Document 1 may be referred to as an "optical coupling layer." Furthermore, "extracting light" in Patent Document 1 may be referred to as "taking out light" or "coupling light."

[0005] Furthermore, Patent Documents 2 and 3 disclose a method of forming a light extraction layer having regions with different refractive indices by applying an additional material by printing onto a nanovoid polymer layer so that the additional material penetrates into the nanovoid polymer layer, thereby forming regions where the additional material has penetrated and regions where it has not.

[0006] International Publication No. 2019 / 182100 U.S. Patent Application Publication No. 2015330597 U.S. Patent Application Publication No. 20170031078

[0007] However, according to the study by the present inventors, it was found that, for example, it was difficult to efficiently form a relatively high-definition pattern with the method using laser light irradiation described in Patent Document 1. Furthermore, even when the methods described in Patent Documents 2 and 3 were used, it was sometimes difficult to accurately form regions having different refractive indices in a pattern as designed.

[0008] Therefore, an object of the present invention is to provide a method that can form areas with different refractive indices in a designed pattern more accurately than conventional methods, and further to provide an optical component having such an optical layer.

[0009] According to an embodiment of the present invention, the following solutions are provided:

[0010] [Item 1] An optical member having a first layer having a porous structure, wherein the first layer includes a first region having the porous structure and a second region in which voids in the porous structure are filled with a resin composition, wherein the second region includes a plurality of discretely arranged island regions, and wherein H / P is less than 0.20, where P% is an area ratio of the second region to the first layer and H% is a haze value of the first layer.

[0011] [Item 2] The optical member according to Item 1, wherein the diameter of each of the plurality of island regions, which is equivalent to an equal circumferential ellipse, is about 1 μm or more and about 500 μm or less.

[0012] [Item 3] The optical member according to item 1 or 2, wherein the resin composition includes a cured curable resin composition.

[0013] [Item 4] The optical member according to Item 3, wherein the resin composition contains a polyfunctional silicon compound.

[0014] [Item 5] The optical member according to Item 3, wherein the resin composition contains an acrylic resin.

[0015] [Item 6] The optical member according to any one of Items 3 to 5, wherein the resin composition further contains a solvent.

[0016] [Item 7] The optical waveguide further includes a second layer in contact with the first main surface of the first layer, and the refractive index of the first region is n １ , the refractive index of the second region is n ２ , the refractive index of the second layer is n ３ When this is the case, n １ <n ２ and n １ <n ３ 7. The optical member according to any one of items 1 to 6,

[0017] [Item 8] n １ is 1.30 or less, and n ２ 8. The optical element according to item 7, wherein the σ is 1.43 or more.

[0018] [Item 9] The optical member according to item 7 or 8, wherein the second layer is an adhesive layer or a substrate layer.

[0019] [Item 10] The optical member according to any one of Items 1 to 9, wherein the first layer contains a porous silica material.

[0020] [Item 11] An optical element comprising: the optical member according to any one of items 1 to 10; and a light guide layer.

[0021] [Item 12] The optical element according to Item 11, further comprising a direction changing layer disposed on the opposite side of the optical member from the light guiding layer.

[0022] [Item 13] A method for manufacturing an optical member, comprising: Step A: preparing a porous layer; Step B: forming a plurality of discrete island regions on the porous layer with a solution Sa containing a curable resin composition, wherein the concentration of the solution Sa is more than 60 mass % and less than 99 mass %; Step C: filling voids in the porous layer with the solution Sa; and Step D: curing the curable resin composition contained in the solution Sa in the voids.

[0023] [Item 14] The method for manufacturing an optical member according to Item 13, wherein the step B includes a step BS1 of forming a plurality of discrete island regions on a film using the solution Sa, and a step BS2 of transferring the solution Sa on the film onto the porous layer.

[0024] [Item 15] The method for producing an optical member according to Item 14, wherein step BS2 is performed at a lamination pressure of 0.3 MPa or less.

[0025] [Item 16] The method for manufacturing an optical member according to Item 13, wherein the step B includes a step BS1 of forming a plurality of discrete island regions on the adhesive layer using the solution Sa, and a step BS2 of transferring the solution Sa on the adhesive layer onto the porous layer.

[0026] [Item 17] The method for manufacturing an optical member according to Item 16, wherein the step BS1 includes a step BS3 of forming a plurality of discrete island regions on a film using the solution Sa, and a step BS4 of transferring the solution Sa on the film onto the adhesive layer.

[0027] [Item 18] The method for manufacturing an optical member according to any one of Items 13 to 17, wherein the step of forming the discrete island regions using the solution Sa includes the steps of forming the discrete island regions using a solution Sb containing the curable resin composition at a concentration of 60 mass% or less, and removing a portion of the solvent contained in the solution Sb.

[0028] According to an embodiment of the present invention, a method for forming a light extraction layer having a relatively fine pattern more efficiently than conventional methods is provided, and further, an optical member having such a light extraction layer, a method for manufacturing the same, and an optical element having such an optical member are provided.

[0029] 1 is a schematic cross-sectional view of an optical element 100 having an optical member according to an embodiment of the present invention. FIG. 2 is a schematic plan view showing an example of the arrangement of first regions 12a and second regions 14a in a first layer 10a of an optical member according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing one step in a manufacturing process of the optical member 100. FIG. 4 is a schematic cross-sectional view showing one step in a manufacturing process of the optical member 100. FIG. 5 is a schematic cross-sectional view showing one step in a manufacturing process of the optical member 100. FIG. 6 is a schematic cross-sectional view showing one step in a manufacturing process of the optical member 100. FIG. 7 is an optical microscope image of Sample No. 7. FIG. 8 is an optical microscope image of Sample No. 9. FIG. 10 is an optical microscope image of Sample No. 11. FIG. 12 is an optical microscope image of Sample No. 12. FIG. 8 is a graph showing the relationship between the concentration of solution Sa and the haze value H / area ratio P. 1 is a schematic cross-sectional view of an optical element 200A according to an embodiment of the present invention; FIG. 2 is a schematic cross-sectional view of an optical element 200B; FIG. 3 is a schematic cross-sectional view of an optical element 200C; FIG. 4 is a schematic cross-sectional view of a shape-transfer film 70; and FIG. 5 is a schematic cross-sectional view showing recesses 74 of the shape-transfer film 70.

[0030] Hereinafter, an optical member, a method for manufacturing an optical member, and an optical element including an optical member according to an embodiment of the present invention will be described with reference to the drawings. The embodiment of the present invention is not limited to the following examples.

[0031] 1 shows a schematic cross-sectional view of an optical element 100 having an optical member according to an embodiment of the present invention. The optical member according to an embodiment of the present invention has a first layer 10 having a porous structure. The optical member may be composed of the first layer 10 and a base layer 30, or may be composed of the first layer 10 and an adhesive layer 20. It is sufficient that the optical member according to an embodiment of the present invention has at least the first layer 10.

[0032] Optical elements according to embodiments of the present invention can, for example, extract light propagating through a light guide layer from the main surface of the light guide layer or guide it to an optical element arranged in contact with the main surface. Guiding light propagating through a light guide layer to an optical element arranged in contact with the main surface of the light guide layer is referred to as optical coupling, and a layer that performs this function is called an optical coupling layer. For example, optical elements according to embodiments of the present invention are suitable for use as the optical coupling layer of a light guide element described in, for example, Japanese Patent Application No. 2020-127530 (filed July 28, 2020) by the present applicant. As described in the above patent application, the optical coupling layer can be provided between the light guide layer and the direction-changing layer. The direction-changing layer has, for example, multiple internal spaces that form an interface that directs light toward the main surface of the direction-changing layer by total internal reflection. A direction-changing layer having such internal spaces may be, for example, the light distribution structure disclosed in International Publication No. 2019 / 087118. The direction-changing layer may also be a known prism sheet. The entire disclosures of Japanese Patent Application No. 2020-127530 and International Publication No. 2019 / 087118 are incorporated herein by reference.

[0033] The optical element 100 includes a first layer 10, a light guide layer 50, an adhesive layer 20 provided between the first layer 10 and the light guide layer 50, and a base layer 30 that supports the first layer 10. As will be described later, the first layer 10 exemplified here is formed on the base layer 30.

[0034] The first layer 10 includes a first region 12 having a porous structure and a second region 14 in which voids in the porous structure are filled with a resin composition. The second region 14 includes a plurality of discretely arranged island regions. As will be described later with reference to examples, the first layer 10 is characterized in that, when the area ratio of the second region 14 to the first layer 10 is P % and the haze value of the first layer is H %, H / P is less than 0.20. The area ratio P can be determined, for example, over a 10 mm x 10 mm region centered on the location where the haze value is measured.

[0035] If the layer in contact with the first main surface of the first layer 10 is the second layer (here, the adhesive layer 20), the refractive index of the first region 12 is n １ , the refractive index of the second region 14 is n ２ , the refractive index of the second layer 20 is n ３ Then, n １ <n ２ and n １ <n ３ In this case, for example, n ２ <n ３ The relationship between n and n is satisfied. １ is, for example, 1.30 or less, and n ２ is, for example, 1.43 or more, and n ３ can be, for example, 1.45 or greater.

[0036] The first layer 10 may be formed, for example, of a porous silica material. The porosity of the porous silica material is greater than 0% and less than 100%. To obtain a low refractive index, the porosity is preferably 40% or more, more preferably 50% or more, and even more preferably 55% or more. There is no particular upper limit to the porosity, but from the viewpoint of strength, it is preferably 95% or less, and more preferably 85% or less.

[0037] The refractive index of silica (the matrix portion of the porous silica body) is preferably, for example, 1.41 or more and 1.43 or less. The resin composition filled into the voids of the first layer 10 is a cured curable resin composition (sometimes referred to as a "cured resin composition"). From the viewpoint of mass production, the curable resin composition is preferably a photocurable resin composition. Photocurable resin compositions are, for example, polyfunctional silicon compounds (e.g., silsesquioxane derivatives: compounds having multiple photocurable functional groups in a silsesquioxane skeleton) or acrylic resins (e.g., urethane acrylate). The refractive index of general resins is generally 1.45 or more and 1.70 or less. The porosity of the porous structure contained in the first layer 10 and the refractive index n of the cured resin composition are ３ By adjusting the refractive index n ２ can be controlled. ２ -n ３ is preferably equal to or less than 0.1, which can suppress total internal reflection at the interface between the second layer 20 and the second region 14 of the first layer 10.

[0038] By arranging the first regions 12 and the second regions 14 in a predetermined pattern, the first layer 10 can function as, for example, an optical coupling layer. The optical coupling layer is disposed between two optical layers, for example, a light guide layer and a light redirecting layer, and guides a portion of the light propagating through the light guide layer to the light redirecting layer. The light redirecting layer has, for example, an interface (or surface) that imparts a layer-normal component to the propagating light. The light redirecting layer can be, for example, a prism sheet.

[0039] Referring again to FIG. 1, the function of the optical element 100 according to the embodiment of the present invention will be described.

[0040] The first layer 10, adhesive layer 20, light guide layer 50, and base layer 30 of the optical element 100 have principal surfaces parallel to the XY plane. Light emitted from the light source LS toward the light-receiving end surface (not shown) of the light guide layer 50 propagates in the Y direction within the light guide layer 50 (guided light L Ｐ A part of the light incident on the light guide layer 50 is optically coupled (extracted) to the base layer 30 by the first layer 10 and the adhesive layer 20 (optical members) and is emitted in the Z direction (emitted light L ＥOf course, the propagation direction of light varies (distribution) from the Y direction, and the emission direction of light also varies (distribution) from the Z direction. The X direction is perpendicular to the Y and Z directions.

[0041] Light L propagating in the light guide layer 50 Ｐ is totally internally reflected at the interface between the second layer 20 and the first region 12 of the first layer 10, and light incident on the interface between the second layer 20 and the second region 14 of the first layer passes through the second region 14 of the first layer 10 and the base layer 30 without being totally internally reflected, and is emitted from the optical element 200B.

[0042] By adjusting the arrangement of the first regions 12 and second regions 14 of the first layer 10 in the layer plane (parallel to the XY plane), it is possible to control the light distribution (emission intensity distribution, emission angle distribution, etc.) of light extracted from the light guide layer 50 by the optical member 100a (optically coupled with the base layer 30). The arrangement of the first regions 12 and second regions 14 in the first layer 10 is appropriately set according to the required light distribution. Therefore, if the second regions 14 cannot be formed in the designed pattern, the desired light distribution cannot be obtained.

[0043] 2 , for example, the first layer 10 has a plurality of circular second regions 14b discretely arranged within the first region 12. The diameter of the second regions 14 is, for example, not less than about 1 μm and not more than about 500 μm. Furthermore, the pitch Px between adjacent second regions 14 in the X direction and the pitch Py between adjacent second regions 14 in the Y direction are independently, for example, not less than about 2 μm and not more than about 5000 μm. The pitches Px and Py are the distances between the centers (area centers of gravity) of adjacent second regions 14 in the X direction and Y direction, respectively.

[0044] The arrangement of the first regions 12 and the second regions 14 in the first layer 10 can be modified in various ways. Furthermore, the shape of each of the second regions 14 is not limited to a circle, and can be various shapes.

[0045] The shape, dimensions, in-plane density of the first layer 10, and occupancy rate of the second region 14 within the first layer 10 can be appropriately changed depending on the purpose and application of the optical member. For example, when good visibility, such as transparency, is required, the major axis of each second region 14 is preferably 100 μm or less, and more preferably 70 μm or less. For example, as shown in FIG. 2, in the case of a circular second region 14, the diameter of the circle is preferably 100 μm or less. In applications where devices equipped with optical members are viewed from a relatively close distance, such as mobile displays and small signage, the visibility of the second region 14 can be reduced. When the second region is not circular, it can be evaluated, for example, by the diameter equivalent to an isocircular ellipse.

[0046] Next, a method for manufacturing an optical element having a first layer 10 according to an embodiment of the present invention will be described. The first layer 10 is characterized in that, when the area ratio of the second region 14 to the first layer 10 is P %, and the haze value of the first layer is H %, H / P is less than 0.20. If the haze value is greater than 0.20%, the desired light distribution characteristics may not be obtained due to the influence of diffused light (light scattered from the area surrounding the second region 14).

[0047] An optical member having the first layer 10 having the above-described characteristics can be manufactured, for example, by the following manufacturing method.

[0048] A method for manufacturing an optical member according to an embodiment of the present invention includes the steps of: Step A: preparing a porous layer; Step B: forming a plurality of discrete island regions on the porous layer using a solution Sa containing a curable resin composition, the solution Sa having a concentration of more than 60 mass %; Step C: filling voids in the porous layer with the solution Sa; and Step D: curing the curable resin composition contained in the solution Sa in the voids. When the curable resin composition is photocurable, it can be cured, for example, by irradiating it with ultraviolet light.

[0049] For example, step B includes step BS1 of forming a plurality of discrete island regions on a film using solution Sa, and step BS2 of transferring the solution Sa on the film onto a porous layer. Step BS2 is preferably performed at a lamination pressure of 0.3 MPa or less. Step B may also include, for example, step BS1 of forming a plurality of discrete island regions on an adhesive layer using solution Sa, and step BS2 of transferring the solution Sa on the adhesive layer onto a porous layer. Furthermore, step BS1 may also include, for example, step BS3 of forming a plurality of discrete island regions on a film using solution Sa, and step BS4 of transferring the solution Sa on the film onto the adhesive layer.

[0050] The step of forming a plurality of discrete island regions using the solution Sa may include a step of forming a plurality of discrete island regions using a solution Sb containing a curable resin composition at a concentration of 60 mass% or less, and a step of removing a portion of the solvent contained in the solution Sb.

[0051] The step of forming a plurality of discrete island regions using a solution Sb containing a curable resin composition at a concentration of 60% by mass or less can be performed using, for example, various printing methods. Gravure printing can handle a solution Sb with a viscosity of 0.1 to 1 Pa·s, making it preferable to inkjet methods, which can only handle solutions Sb with relatively low viscosities. Although the curable resin composition (e.g., a silsesquioxane derivative or an acrylic resin) is liquid, it is preferably diluted with a solvent (e.g., an organic solvent such as alcohol or toluene) and used as a solution from the viewpoints of coatability during gravure printing and filling (permeability, penetration) into porous structures. The step of removing a portion of the solvent contained in the solution Sb is performed, for example, by heating a film (adhesive layer, substrate layer) on which a plurality of discrete island regions have been formed using the solution Sb.

[0052] Next, a specific example of a method for manufacturing an optical member will be described with reference to FIGS. 3A to 3E.

[0053] First, as shown in Fig. 3A, a layer 10P having a porous structure is formed on a substrate layer 30. The porous layer 10P can be formed, for example, by the method exemplified below. The element having the layer 10P that will become the first layer 10 is designated by the reference symbol 10SA. Although the structure changes as the process progresses, the same reference symbol is used.

[0054] Meanwhile, as shown in FIG. 3B , a solution Sb containing a curable resin composition at a concentration of 60% by mass or less is used to form a plurality of discrete island regions on a transfer substrate (e.g., PET) 30T, for example, by gravure printing. For example, the pattern shown in FIG. 2 is formed using a gravure plate (circular cell diameter 50 μm, cell depth 8 μm, cell pitches Px and Py both 200 μm). The diameter of the circular island regions in the pattern formed with solution Sb is approximately 100 μm. The gravure roll is printed on the peripheral surface of a roll with a diameter of 130 mm and a width of 110 mm at a printing speed of 14 m / min and an impression cylinder nip pressure of 0.86 MPa. The element containing the curable resin composition is designated by the reference symbol 10SB. Although the structure changes as the process progresses, it is indicated by the same reference symbol.

[0055] This element 10SB is dried to remove part of the solvent contained in the solution Sb, thereby obtaining a solution Sa. In this way, a plurality of discrete island regions formed of the solution Sa containing the curable resin composition are obtained.

[0056] Next, as shown in FIG. 3C , a plurality of discrete island regions formed with a solution Sa containing a curable resin composition are transferred onto the layer 10P of the element 10SA. The solution Sa fills the voids in the porous structure of the layer 10P of the element 10SA. After this, ultraviolet light is irradiated from the substrate 30 side (for example, Fusion UV with a UVA wavelength of 600 mJ / cm ). ２The curable resin composition is cured by irradiating the solution Sa containing the curable resin composition with light (lamp: V bulb) so that the regions corresponding to the discrete island regions formed with the solution Sa containing the curable resin composition become second regions, and the remaining regions become first regions, thereby obtaining the first layer 10. Note that at this time, depending on the amount of solution Sa used to form each island region, a layer not containing the curable resin may be formed on the substrate 30 side or the opposite side (the first regions may be continuously present). The element containing element 10SA and element 10SB is designated by reference symbol 10SAB.

[0057] Next, as shown in Fig. 3D, the transfer substrate 30T is peeled off, and as shown in Fig. 3E, the adhesive layer 20 formed on the release sheet 40 is attached to the first layer 10. The release sheet 40 of this element 10SAB is peeled off, and the element is attached to another optical element, thereby obtaining an optical element (for example, the optical element 200A shown in Fig. 7).

[0058] Here, a plurality of discrete island regions are formed on the transfer substrate 30T using a solution Sb containing a curable resin composition at a concentration of 60% by mass or less, but they may also be formed on an adhesive layer. Alternatively, a plurality of discrete island regions may be formed on the transfer substrate 30T using a solution Sb containing a curable resin composition at a concentration of 60% by mass or less, and then transferred onto the adhesive layer. The discrete island regions formed using the solution Sa containing the curable resin composition may then be transferred onto the layer 10P of the element 10SA. Alternatively, the solution Sa containing the curable resin composition may be applied directly onto the layer 10P of the element 10SA so as to form a plurality of discrete island regions.

[0059] In the above manufacturing method, in the step of forming a plurality of discrete island regions on the porous layer with a solution Sa containing a curable resin composition, it is important that the concentration of the solution Sa is more than 60 mass %. This will be explained using experimental examples.

[0060] Here, the following two types of solution Sb were prepared.

[0061] First solution A: TX100 (Toagosei / silsesquioxane derivative) 90 parts B: Celloxide (Daicel / alicyclic bifunctional epoxy) 10 parts C: CPI101 (Sanapro / cationic initiator) 5 parts Then, D: isobutyl alcohol was added to dilute and adjust the concentration of (A+B+C) to 70% by mass, and then mixed uniformly with a stirrer.

[0062] Second solution: Mix A and B in the following amounts:

[0063] A: 100 parts of UV-1700TL (Mitsubishi Chemical / polyurethane acrylate + acrylic acid ester + toluene mixture, solid content 80 wt%) B: 3 parts of Omirad 184 (BASF / photopolymerization initiator) Then, C: toluene was added and diluted so that the concentration of (A + B + C) became 60% by mass, and then mixed uniformly with a stirrer.

[0064] Solutions Sa with different concentrations were obtained by changing the drying conditions for solution Sb (none, 2 minutes at 80°C, 5 minutes at 80°C). Using the first and second solutions described above, samples 1 to 6 were prepared with cell pitches Px and Py of 150 μm, according to the method illustrated with reference to FIGS. 3A to 3E. Samples 7 to 12 were also prepared, which were identical to samples 1 to 6 except that the cell pitches Px and Py were changed to 200 μm. Furthermore, sample 13 was prepared, in which the concentration of solution Sa was 99% by mass (see Table 1 below).

[0065] It was found that the morphology of the second region of the first layer 10 formed on the acrylic plate differed depending on the concentration of the solution Sa.

[0066] 4A to 4C show optical microscope images of Samples Nos. 7 to 9 formed using the first solution, and FIGS. 5A to 5C show optical microscope images of Samples Nos. 10 to 12 formed using the second solution.

[0067] 4A to 4C, it can be seen that there is a white area due to light scattering around the second region (dark region) which is nearly circular (diameter approximately 100 μm). If light is scattered, the desired light distribution characteristics may not be obtained, so it is preferable that the area of ​​the white area in the figure is small. It can be seen that the area of ​​the white area becomes smaller as the concentration of solution Sa becomes higher.

[0068] 5A to 5C, it can be seen that the area of ​​the white region is particularly large in Sample No. 11 in FIG. 5B.

[0069] The degree to which this white region adversely affected the optical properties was evaluated using the haze value (a numerical value representing the ratio of diffuse transmittance to total light transmittance expressed as a percentage). The haze value was measured using a haze meter (HM-150N, manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with JIS K 7136. The results are shown in Table 1. The haze value Ha indicates the haze value obtained by measuring the first layer 10 on the acrylic plate, and the haze value H indicates the value (Ha-Hb) obtained by subtracting the haze value Hb (0.4325) of the acrylic plate alone from the haze value Ha. The area ratio P indicates the area ratio (design value) of the second region 14 to the first layer 10, and was 34.91% for Samples Nos. 1 to 6 and 19.63% for Samples Nos. 7 to 13. The haze value H / area ratio P is a parameter that represents the contribution of the second region 14 to an increase in the haze value. A graph showing the relationship between the concentration of the solution Sa and the haze value H / area ratio P is shown in FIG.

[0070]

[0071] As can be seen from the results in Table 1 and Figure 6, the haze value H / area ratio P for Sample No. 5 and Sample No. 11, which had a solution Sa concentration of 60% by mass, were 0.233 and 0.205 (0.21), respectively, which were values ​​greater than 0.20. The magnitude of this haze value H / area ratio P value corresponds to the size of the white area in the optical microscope images shown in Figures 4A to 4C and 5A to 5C. Therefore, in order to suppress scattering from the area surrounding the second region, the haze value H / area ratio P is preferably less than 0.20, more preferably 0.15 or less, and even more preferably 0.10 or less.

[0072] To form such a second region, the concentration of solution Sa is preferably greater than 60% by mass, more preferably 65% ​​by mass or more, even more preferably 70% by mass or more, and even more preferably 96% by mass or more. On the other hand, a solvent-free curable resin composition (liquid) can also be used. However, if the concentration of solution Sa is 99% by mass or more, i.e., if the concentration of solution Sa is too high, light scattering may increase. Therefore, the concentration of solution Sa is preferably less than 99% by mass, more preferably 98% by mass or less. It is believed that the inclusion of even a small amount of solvent improves the affinity (wettability) with the porous structure and improves the penetration and filling ability of the curable resin composition into the voids of the porous structure. After the curable resin composition has penetrated into the voids of the porous structure, the remaining solvent may be removed, for example, by drying. In an optical element in which a second region is formed using a solution containing a curable resin composition and a solvent, the solvent in the second region may not be completely removed even after the optical element is completed or during use, and a small amount may remain. Residual solvent can be detected by micro-mass spectrometry, for example, gas chromatography mass spectrometry.

[0073] Next, examples of components that can be suitably used in the optical element according to the embodiment of the present invention will be described.

[0074] (Light Guide Layer) A wide variety of known light guide layers (light guides) can be used for the light guide layer. The light guide layer can typically be composed of a film or plate of resin (preferably transparent resin). The resin may be a thermoplastic resin or a photocurable resin. Examples of thermoplastic resins include (meth)acrylic resins such as polymethyl methacrylate (PMMA) and polyacrylonitrile, polyester resins such as polycarbonate (PC) resin and PET, cellulose resins such as triacetyl cellulose (TAC), cyclic polyolefin resins, and polystyrene resins. Examples of photocurable resins that can be used include epoxy acrylate resins and urethane acrylate resins. These resins may be used alone or in combination.

[0075] The thickness of the light guide layer may be, for example, 100 μm or more and 100 mm or less, and is preferably 50 mm or less, more preferably 30 mm or less, and even more preferably 10 mm or less.

[0076] Refractive index n of the light guide layer ＧＰ is, for example, the refractive index n of the second layer ３ The lower limit is preferably 1.43 or more, more preferably 1.47 or more. On the other hand, the upper limit of the refractive index of the light guide layer is 1.7.

[0077] Refractive index n of the light guide layer ＧＰ is set so that when the first region of the first layer is disposed in direct contact with the light guide layer, light is totally internally reflected at the interface between the light guide layer and the first region of the first layer. When the first region of the first layer is disposed on the light guide layer via a second layer, the refractive index n of the first region is set so that light is totally internally reflected at the interface between the second layer and the first region. １ and the refractive index of the second layer n ３ is set, and the refractive index n of the light guide layer is set so that total internal reflection is unlikely to occur at the interface between the light guide layer and the second region. ＧＰ and the refractive index of the second region n ２ is set. ＧＰ -n ２ is preferably 0.1 or less.

[0078] Although a conventional light guide layer having an uneven surface can be used as the light guide layer, a light guide layer having a substantially flat surface, such as the light guide layer 50 shown in Figure 1, can be preferably used. The optical element 100 functioning as an optical coupling layer according to the embodiment of the present invention has a substantially flat main surface, and therefore can be easily laminated with the light guide layer 50 having a substantially flat surface, as well as with other optical elements having substantially flat surfaces. A substantially flat surface means that the uneven surface does not refract or diffusely reflect light.

[0079] (Porous Layer, First Region of First Layer) The first layer has a porous structure. The first layer can be formed from a porous layer. Porous layers suitable for use as the first layer include silica particles, silica particles with micropores, approximately spherical particles such as 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 porous layer 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 porous layer may be bonded to each other via a small amount (e.g., less than the mass of the particles) of a single binder component. The porosity and refractive index of the porous layer can be adjusted by the particle size, particle size distribution, etc. of the particles constituting the porous layer.

[0080] Methods for obtaining a porous layer include, for example, the method for forming a low refractive index layer described in WO 2019 / 146628, as well as methods described in JP 2010-189212 A, JP 2008-040171 A, JP 2006-011175 A, WO 2004 / 113966 A, JP 2017-054111 A, JP 2018-123233 A and JP 2018-123299 A and references thereto. All of the disclosures of these publications are incorporated herein by reference.

[0081] A porous silica material can be suitably used as the porous layer. The porous silica material can be produced by, for example, the following methods. Examples include a method of hydrolyzing and polycondensing a silicon compound; hydrolyzable silanes and / or silsesquioxane, and at least one of their partial hydrolyzates and dehydration condensates; a method of using porous particles and / or hollow fine particles; 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. However, the porous layer is not limited to a porous silica material, and the production method is not limited to the exemplified production methods, and any production method may be used. Note that silsesquioxane can be (RSiO１．５ , R is a hydrocarbon group) as a basic structural unit, and ２ Although it is strictly different from silica, which has silsesquioxane as a basic structural unit, it has something in common with silica in that it has a network structure cross-linked by siloxane bonds. Therefore, in this specification, porous materials containing silsesquioxane as a basic structural unit are also referred to as porous silica materials or silica-based porous materials.

[0082] The porous silica material can be composed of microporous particles of a gel-like silicon compound bonded to one another. 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 (e.g., siloxane bonded) by, for example, the action of a catalyst, light irradiation, heating, etc.

[0083] The lower limit of the thickness of the porous layer (first layer) may be, for example, greater than the wavelength of the light used. Specifically, the lower limit is, for example, 0.3 μm or more. There is no particular limitation on the upper limit of the thickness of the first layer, but it is, for example, 5 μm or less, more preferably 3 μm or less. If the thickness of the first layer is within the above range, the surface irregularities will not be large enough to affect lamination, making it easy to form a composite or laminate with other components.

[0084] The refractive index of the porous layer, i.e., the refractive index n of the first region of the first layer １ The refractive index n1 of the first region is preferably 1.30 or less. Total internal reflection is likely to occur at the interface in contact with the first region, that is, the critical angle can be reduced. The refractive index n1 of the first region is more preferably 1.25 or less, further preferably 1.18 or less, and particularly preferably 1.15 or less. １ The lower limit of is not particularly limited, but is preferably 1.05 or more from the viewpoint of mechanical strength.

[0085] The lower limit of the porosity of the porous layer, i.e., the porosity of the first region of the first layer, is, for example, 40% or more, preferably 50% or more, more preferably 55% or more, and even more preferably 70% or more. The upper limit of the porosity of the porous layer is, for example, 90% or less, more preferably 85% or less. By ensuring that the porosity is within the above range, the refractive index of the first region can be set to an appropriate range. The porosity can be calculated, for example, from the refractive index measured with an ellipsometer using the Lorentz-Lorenz formula.

[0086] The film density of the porous layer, i.e., the film density of the first region of the first layer, is, for example, 1 g / cm ３ or more, preferably 10 g / cm ３ More preferably, 15 g / cm ３ On the other hand, the film density is, for example, 50 g / cm ３ and preferably 40 g / cm ３ More preferably, it is 30 g / cm or less. ３ More preferably, it is 2.1 g / cm or less. ３ The film density range is, for example, 5 g / cm ３ More than 50g / cm ３ and preferably 10 g / cm ３ 40g / cm or more ３ More preferably, it is 15 g / cm or less. ３ More than 30g / cm ３ Alternatively, the range may be, for example, 1 g / cm ３ 2.1g / cm or more ３ The film density can be measured by known methods.

[0087] (Second Region of First Layer) The second region of the first layer is formed by filling voids in the porous layer with a cured resin composition. The refractive index n of the second region ２ is the refractive index n of the first region １ and the refractive index of the second layer n ３ and n １ <n ２ and n １ <n３ The relationship of n is satisfied. ２ By satisfying this relationship, scattering of light due to reflection and refraction at the interface between the first region and the second region in the surface direction of the first layer can be suppressed. ２ The lower limit value of is, for example, more than 1.30, preferably 1.35 or more, and more preferably 1.40 or more.

[0088] The first and second regions of the first layer are formed from a common porous layer. That is, the first layer has a continuous porous structure throughout the first and second regions. The refractive index of the material constituting the matrix portion of the porous layer (the portion other than the voids in the porous layer) is defined as n Ｍ Then, the refractive index of the porous layer, i.e., the refractive index of the first region, n １ is n Ｍ and the refractive index of the second region n ２ is n Ｍ and the porosity and the refractive index n of the second layer (resin composition). ３ For example, as described above, when a porous silica material is used as the porous layer, n Ｍ is, for example, 1.41 or more and 1.43 or less, and the refractive index of the resin is n Ｍ If n is greater than 1.45 (for example, 1.45 or greater and 1.70 or less), １ <n ２ <n ３ The following relationship is obtained.

[0089] Preparation example of coating liquid (microporous particle-containing liquid) for forming porous layer (first region of first layer) (1) Gelation of silicon compound 0.95 g of methyltrimethoxysilane (MTMS), a precursor of a gel-like silicon compound, was dissolved in 2.2 g of dimethyl sulfoxide (DMSO) to prepare mixed liquid A. 0.5 g of a 0.01 mol / L aqueous oxalic acid solution was added to this mixed liquid A, and the mixture was stirred at room temperature for 30 minutes to hydrolyze the MTMS, thereby producing mixed liquid B containing tris(hydroxy)methylsilane.

[0090] To 5.5 g of DMSO, 0.38 g of 28% by mass ammonia water 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 (polymethylsilsesquioxane).

[0091] (2) Aging Treatment The mixed solution C containing the gel silicon compound prepared as above was incubated at 40° C. for 20 hours to carry out an aging treatment.

[0092] (3) Pulverization 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 performed three times to replace the solvent, and mixed solution D was obtained. Next, the gel-like silicon compound in mixed solution D was subjected to a pulverization process (high-pressure media-less pulverization). The pulverization process (high-pressure media-less pulverization) was performed using a homogenizer (manufactured by SMT Corporation, product name "UH-50"), and 1.85 g of the gel-like compound and 1.15 g of IPA in mixed solution D were weighed into a 5 cc screw bottle, and then pulverized for 2 minutes under conditions of 50 W and 20 kHz.

[0093] This grinding process pulverized the gel-like silicon compound in Mixed Liquid D, thereby converting Mixed Liquid D' into a sol of the pulverized material. The volume average particle size, which indicates the particle size variation of the pulverized material contained in Mixed Liquid D', was measured using a dynamic light scattering Nanotrac particle size analyzer (manufactured by Nikkiso Co., Ltd., Model UPA-EX150) and found to be 0.50 to 0.70. Furthermore, to 0.75 g of this sol (Mixed Liquid C'), 0.062 g of a 1.5 wt% MEK (methyl ethyl ketone) solution of a photobase generator (product name WPBG266, Wako Pure Chemical Industries, Ltd.) and 0.036 g of a 5% MEK solution of bis(trimethoxysilyl)ethane were added to obtain a coating liquid for forming a porous layer (a liquid containing microporous particles). The coating liquid for forming a porous layer contains a porous silica material having silsesquioxane as its basic structure.

[0094] The coating solution was applied (coated) onto the surface of an acrylic resin film (thickness: 40 μm) prepared according to Production Example 1 of JP 2012-234163 A to form a coating film. The coating film was dried by treating at a temperature of 100°C for 1 minute, and then the dried coating film was irradiated with 300 mJ / cm using light with a wavelength of 360 nm. ２ The acrylic resin film was then irradiated with UV light at a light irradiation dose (energy) of 1.00 to obtain a laminate (acrylic film with a porous silica layer) in which a porous layer (a porous silica body formed by chemical bonding of microporous silica particles) was formed on the acrylic resin film. The refractive index of the porous layer was 1.15.

[0095] For example, the following optical element can be obtained by using the optical member according to the embodiment of the present invention.

[0096] FIG. 7 is a schematic cross-section of an optical element 200A according to an embodiment of the present invention, FIG. 8 is a schematic cross-section of an optical element 200B according to an embodiment of the present invention, and FIG. 9 is a schematic cross-section of an optical element 200C according to an embodiment of the present invention.

[0097] 7, 8, and 9 each include a first layer 10, base material layers 30A and 30B, a shaping film 70, and adhesive layers 92, 94, and 96. The shaping film 70 and the adhesive layer 94 form a direction-changing layer having a plurality of internal spaces 74.

[0098] As the shaping film 70, for example, a concave-convex shaping film shown in FIGS. 10A and 10B can be used.

[0099] FIG. 10A shows a plan view of a portion of the unevenly shaped film 70 as seen from the uneven surface side. FIG. 10B also shows a 10B-10B' cross-sectional view of the unevenly shaped film of FIG. 10A. A plurality of recesses 74 having a triangular cross section with a length L of 80 μm, a width W of 14 μm, and a depth H of 10 μm were arranged at intervals of width E (155 μm) in the X-axis direction. Furthermore, a pattern of such recesses 74 was arranged at intervals of width D (100 μm) in the Y-axis direction. The density of the recesses 74 on the surface of the unevenly shaped film was 3612 / cm ２10B, θa and θb were both 41°, and the area occupied by the recesses 74 when the film was viewed in plan from the uneven surface side was 4.05%.

[0100] Such a textured film can be produced according to the method described in JP-A-2013-524288. Specifically, the surface of a polymethyl methacrylate (PMMA) film is coated with lacquer (Finecure RM-64, manufactured by Sanyo Chemical Industries, Ltd.: an acrylate-based photocurable resin), an optical pattern is embossed on the film surface containing the lacquer, and then the lacquer is cured (for example, ultraviolet irradiation conditions: D bulb, 1000 mJ / cm ２、 320 mW / cm ２ The total thickness of the film having the concave-convex shape was 130 μm, and the haze was 0.8%.

[0101] In this way, by adopting a configuration in which a laminate stacked on multiple base layers is bonded together with an adhesive layer, optical elements can be mass-produced using a roll-to-roll method or a roll-to-sheet method.

[0102] The thickness of the base layer 30A, 30B is preferably 1 μm or more and 1000 μm or less, more preferably 10 μm or more and 100 μm or less, and more preferably 20 μm or more and 80 μm or less. The refractive index of the base layer 30A, 30B is preferably 1.40 or more and 1.70 or less, and more preferably 1.43 or more and 1.65 or less.

[0103] The thicknesses of the adhesive layers 92, 94, and 96 are each independently, for example, from 0.1 μm to 100 μm, preferably from 0.3 μm to 100 μm, and more preferably from 0.5 μm to 50 μm. The refractive indexes of the adhesive layers 92, 94, and 96 are each independently preferably from 1.42 to 1.60, and more preferably from 1.47 to 1.58. The refractive indexes of the adhesive layers 92, 94, and 96 are preferably close to the refractive index of the light-guiding layer 50 or the shaping film 70 to which they are in contact, and the absolute value of the difference in refractive index is preferably 0.2 or less.

[0104] When mass-producing such optical elements using a roll-to-roll or roll-to-sheet method, the transfer process described with reference to FIG. 3C is preferably performed at a lamination pressure of 0.3 MPa or less. That is, if the lamination pressure exceeds 0.3 MPa during the process of transferring the solution Sa from the transfer substrate (film) 30T onto the porous layer 10P, the white area formed around the second region where the voids in the porous structure are filled with the resin composition may increase. If the white area increases (i.e., if the H / P ratio increases), the light distribution of the light emitted from the optical element may deviate from the desired distribution. For example, if the white area increases, the directivity of the light emitted from the optical element decreases, and the half-value angle (full width at half maximum) of the emitted light increases. In the above experimental example, the transfer process was performed using a hand roller (lamination pressure less than 0.1 MPa).

[0105] Sample optical elements having the same structure as the optical element 200A shown in FIG. 7 were fabricated by varying the lamination pressure during the transfer process, and the half-value angle of the emitted light was measured. The shaped film 70 described with reference to FIGS. 10A and 10B was used as the shaped film 70. The first layer 10 was formed under the same conditions as Sample No. 8 (lamination pressure 0.0 MPa) except for the lamination pressure. A roll-type laminator (LPA330 manufactured by Fujipla Co., Ltd.) was used for lamination, and the lamination pressure was measured using a prescale (manufactured by Fujifilm Corporation, for low pressure (4LW) and extremely low pressure (LLLW)). The lamination pressure was 0.3 MPa (Sample No. 8A) and 0.6 MPa (Sample No. 8B).

[0106] An LED light source was placed at the end of the light guide layer 50 of each sample optical element obtained, and the emitted light L Ｅ The light distribution was measured using an imaging colorimeter (Radiant's ProMetric I-Plus). The size of the measurement area was 35 mm square (the same as the size of the detector lens). From the measured light distribution, the emitted light L Ｅ The half-value angle was calculated.

[0107] The half-value angle of the optical element of Sample No. 8 was 27°, the half-value angle of the optical element of Sample No. 8A was 30°, and the half-value angle of the optical element of Sample No. 8B was 32°. As can be seen, the higher the lamination pressure in the transfer process, the larger the half-value angle and the lower the directivity of the emitted light. For example, to obtain a half-value angle of 30° or less, it is preferable to set the lamination pressure to 0.3 MPa or less.

[0108] The optical member of the present invention is formed into an optical element (light distribution element) together with, for example, a light guide layer, and is applicable to public or general lighting such as frontlights, backlights, window / facade lighting, signage, traffic light lighting, window lighting, wall lighting, table lighting, solar applications, decorative illumination, light shields, light masks, and roof lighting. For example, the optical member of the present invention is suitably used as a component of the frontlight of a reflective display, which is an example of signage. Use of the optical member of the present invention makes it possible to view images or graphics on a reflective display without optical defects such as visible blur caused by scattered or diffracted light.

[0109] 10: First layer, 12: First region, 14: Second region, 30: Base layer, 50: Light guide layer, 70: Textured film, 74: Recess, internal space, 200A, 200B, 200C: Optical element

Claims

1. a first layer having a porous structure; the first layer includes a first region having the porous structure and a second region in which voids in the porous structure are filled with a resin composition; the second region includes a plurality of discretely arranged island regions, An optical member, wherein H / P is less than 0.20, where P % is the area ratio of the second region to the first layer, and H % is the haze value of the first layer.

2. 2. The optical member according to claim 1, wherein the diameter of each of the plurality of island regions equivalent to an equal-circumference ellipse is equal to or greater than about 1 μm and equal to or less than about 500 μm.

3. The optical member according to claim 1 , wherein the resin composition comprises a cured curable resin composition.

4. The optical member according to claim 3 , wherein the resin composition contains a polyfunctional silicon compound.

5. The optical member according to claim 3 , wherein the resin composition contains an acrylic resin.

6. The optical member according to claim 3 , wherein the resin composition further contains a solvent.

7. a second layer in contact with the first main surface of the first layer; The refractive index of the first region is n １ , the refractive index of the second region is n ２ , the refractive index of the second layer is n ３ When this is the case, n １ <n ２ and n １ <n ３ The optical member according to claim 1 , wherein

8. n １ is 1.30 or less, and n ２ The optical member according to claim 7 , wherein the σ is 1.43 or more.

9. The optical member according to claim 7 , wherein the second layer is an adhesive layer or a substrate layer.

10. The optical member according to claim 1 , wherein the first layer contains a porous silica material.

11. The optical member according to any one of claims 1 to 6; Light guide layer An optical element having:

12. The optical element further includes a light redirecting layer disposed on the opposite side of the light guiding layer. The optical element according to claim 11.

13. Step A of preparing a porous layer; Step B is a step of forming a plurality of discrete island regions on the porous layer using a solution Sa containing a curable resin composition, wherein the concentration of the solution Sa is more than 60% by mass and less than 99% by mass; a step C of filling the solution Sa into voids in the porous layer; a step D of curing the curable resin composition contained in the solution Sa in the void; A method for producing an optical member, comprising:

14. 14. The method for manufacturing an optical element according to claim 13, wherein the step B includes a step BS1 of forming a plurality of discrete island regions on a film using the solution Sa, and a step BS2 of transferring the solution Sa on the film onto the porous layer.

15. The method for manufacturing an optical member according to claim 14 , wherein the step BS2 is performed at a lamination pressure of 0.3 MPa or less.

16. The method for manufacturing an optical element described in claim 13, wherein the step B includes a step BS1 of forming a plurality of discrete island regions on an adhesive layer using the solution Sa, and a step BS2 of transferring the solution Sa on the adhesive layer onto the porous layer.

17. 17. The method for manufacturing an optical member according to claim 16, wherein the step BS1 includes a step BS3 of forming a plurality of discrete island regions on a film using the solution Sa, and a step BS4 of transferring the solution Sa on the film onto the adhesive layer.

18. 18. The method for manufacturing an optical member according to claim 13, wherein the step of forming the discrete island regions using the solution Sa includes the steps of: forming the discrete island regions using a solution Sb containing the curable resin composition at a concentration of 60 mass% or less; and removing a portion of the solvent contained in the solution Sb.