Optical member production method

Abstract

This optical member production method comprises: a step A for preparing a porous layer supported on a base material; a step B for removing a region of a part of the porous layer by irradiating the porous layer with laser light, said region of the part that is removed including a discrete plurality of island-like regions; and a step C for disposing a first adhesive layer on the porous layer after step B.

Description

Optical member manufacturing method

[0001] The present invention relates to a method for manufacturing an optical member.

[0002] A known method for extracting light from a light guide layer is to use a light extraction layer having two regions with different refractive indices, as disclosed in, for example, Patent Document 1.

[0003] Patent Literature 1 discloses a method using an inkjet method as an example of a method for forming a light extraction layer. In this method, ink (e.g., an ink-formed pressure-sensitive adhesive) is filled into the voids of a porous layer in a predetermined pattern by the inkjet method, thereby forming a light extraction layer including a low refractive index region in which voids remain and a high refractive index region in which the voids are filled with ink, 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] International Publication No. 2019 / 182100

[0006] However, according to the inventors' investigations, it has been found that in the light extraction layer formed by the inkjet method as disclosed in Patent Document 1, the influence of scattered light (diffused light) from the surrounding area of ​​the high refractive index area is large, and there is a risk that the desired light distribution characteristics may not be obtained. Specifically, it has been found that there are cases where it is not possible to extract light with sufficiently high directionality.

[0007] An object of an embodiment of the present invention is to provide a method for manufacturing an optical element having a light extraction layer that can extract light with sufficiently high directionality.

[0008] According to an embodiment of the present invention, the following solutions are provided:

[0009] [Item 1] A method for manufacturing an optical member, comprising: Step A: preparing a porous layer supported on a substrate; Step B: removing a partial region of the porous layer by irradiating the porous layer with laser light, the removed partial region including a plurality of discrete island regions; and Step C: after Step B, disposing a first adhesive layer on the porous layer.

[0010] [Item 2] The method for producing an optical member according to Item 1, further including: after step C, step D of peeling the substrate from the porous layer; and after step D, step E of arranging a second adhesive layer on the porous layer on the side opposite to the first adhesive layer.

[0011] [Item 3] The absorption coefficient of the substrate for the laser light is 500 cm －１ 3. The method for producing an optical member according to item 1 or 2.

[0012] [Item 4] The method for manufacturing an optical member according to any one of Items 1 to 3, wherein the light intensity distribution of the laser light is a top hat type.

[0013] [Item 5] The method for manufacturing an optical member according to any one of Items 1 to 4, wherein the laser light is an ultraviolet laser light.

[0014] [Item 6] The absorption coefficient of the substrate for the ultraviolet laser light is 1000 cm －１ Item 6. The method for producing an optical member according to Item 5.

[0015] [Item 7] The method for producing an optical member according to any one of Items 1 to 6, wherein in the step A, the porous layer is formed on a release layer provided on the substrate.

[0016] [Item 8] The method for producing an optical member according to Item 7, wherein the release layer is mainly composed of a polymer that does not contain a polar group.

[0017] [Item 9] The method for producing an optical member according to Item 7 or 8, wherein the release layer is formed from a cycloolefin polymer.

[0018] [Item 10] The method for producing an optical member according to Item 9, wherein the release layer has a thickness of 500 nm or less.

[0019] According to an embodiment of the present invention, a method is provided for manufacturing an optical element having a light extraction layer capable of extracting light with sufficiently high directionality.

[0020] 5B is a cross-sectional view schematically showing an optical element 100 having an optical member 1 obtained by a manufacturing method according to an embodiment of the present invention. FIG. 5C is a plan view showing an example of the arrangement of first regions 12 and second regions 14 in a first layer 10 of an optical member 1 (optical element 100). FIG. 5D is a cross-sectional view schematically showing another optical element 200 having an optical member obtained by a manufacturing method according to an embodiment of the present invention. FIG. 5E is a cross-sectional view schematically showing one step of a manufacturing method according to an embodiment of the present invention. FIG. 5F is a cross-sectional view schematically showing one step of a manufacturing method according to an embodiment of the present invention. FIG. 5G is a cross-sectional view schematically showing one step of a manufacturing method according to an embodiment of the present invention. FIG. 5G is a cross-sectional view schematically showing one step of a manufacturing method according to an embodiment of the present invention. FIG. 5H is a cross-sectional view schematically showing a shaped film 72. FIG. 5H is a cross-sectional view schematically showing a cross section along line 5B-5B' in FIG. 5A. FIG. 5I is a cross-sectional view schematically showing an optical member 801 of a reference example. 1 is a diagram for explaining a method for manufacturing an optical member 801; a cross-sectional view schematically showing an optical element 800 having an optical member 801; a cross-sectional view schematically showing an optical member 901 of a comparative example; a diagram for explaining a method for manufacturing an optical member 901; a diagram for explaining a method for manufacturing an optical member 901; a cross-sectional view schematically showing an optical element 900 having an optical member 901; an optical microscope image of an optical member 901 of a comparative example; an optical microscope image of an optical member of Example 1; an optical microscope image of an optical member in which cracks have occurred in a porous layer 10P; an optical microscope image of an optical member in which cracks have not occurred in a porous layer 10P; a diagram showing how a part of a porous layer 10P is peeled off together with a release layer 2 by irradiation with laser light LB, showing a case where the release layer 2 is relatively thick; a diagram showing how a part of a porous layer 10P is peeled off together with a release layer 2 by irradiation with laser light LB, showing a case where the release layer 2 is relatively thin.

[0021] Hereinafter, a method for manufacturing an optical member according to an embodiment of the present invention will be described with reference to the drawings. However, the embodiment of the present invention is not limited to the examples given in the following description.

[0022] [Configuration of Optical Element] Prior to describing the manufacturing method according to an embodiment of the present invention, the configuration of an optical element manufactured using the manufacturing method according to an embodiment of the present invention will be described. The optical element described below 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 of the light guide layer. Guiding light propagating through the 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 acts in this manner is referred to as an optical coupling layer. The optical element described below is suitably used, for example, as the optical coupling layer of the light guide element described in WO 2022 / 025067. As described in WO 2022 / 025067, the optical coupling layer can be provided between the light guide layer and the direction conversion layer. The direction conversion layer has, for example, a plurality of internal spaces that form an interface that directs light toward the main surface of the direction conversion layer by total internal reflection. The light-directing layer having such an internal space may be, for example, the light-distributing structure disclosed in International Publication No. 2019 / 087118. The light-directing layer may also be a known prism sheet. The entire disclosures of International Publication Nos. 2022 / 025067 and 2019 / 087118 are incorporated herein by reference.

[0023] 1 is a cross-sectional view schematically showing an optical element 100 having an optical member 1. As shown in FIG.

[0024] The optical element 1 has a first layer 10, a second layer 20 and a third layer 30 that face each other via the first layer 10, and a substrate layer 40 that supports the first layer 10, the second layer 20, and the third layer 30.

[0025] The second layer 20 and the third layer 30 are each adjacent to the first layer 10 in the layer normal direction, and the third layer 30 is located on the opposite side of the first layer 10 from the second layer 20. Each of the second layer 20 and the third layer 30 is an adhesive layer having adhesive properties. Hereinafter, the second layer 20 may be referred to as the "first adhesive layer," and the third layer 30 may be referred to as the "second adhesive layer." In the illustrated example, the first adhesive layer 20 is provided between the first layer 10 and the light guide layer 50, and the second adhesive layer 30 is provided between the first layer 10 and the substrate layer 40.

[0026] The first layer 10 includes a first region 12 having a porous structure and a second region 14 not having a porous structure. The second region 14 is filled with an adhesive. More specifically, the second region 14 includes the same material as the first adhesive layer 20 and / or the same material as the second adhesive layer 30. The second region 14 also includes a plurality of discretely arranged island-like regions.

[0027] 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 (first adhesive layer) 20 is n ３ When this is the case, n １ <n ２ And, n １ <n ３ The refractive index n of the first region 12 is １ The refractive index n of the second region 14 is, for example, 1.30 or less. ２ and the refractive index n of the first adhesive layer 20 ３ are, for example, 1.43 or more. The refractive index of the third layer (second adhesive layer) 30 is n ４ When this is the case, n １ <n ４ The refractive index n of the second region 14 is ２ , the refractive index n of the first adhesive layer 20 ３ and the refractive index n of the second adhesive layer 30 ４ may be substantially the same.

[0028] The first region 12 having a porous structure 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%. In order to obtain a low refractive index, the porosity of the porous silica material 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. The refractive index of silica (the matrix portion of the porous silica material) is, for example, 1.41 or more and 1.43 or less.

[0029] In this specification, the term "adhesive" is used to include pressure-sensitive adhesives (also called pressure-sensitive adhesives). Specific examples of adhesives for forming the second region 14, the first adhesive layer 20, and the second adhesive layer 30 include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, epoxy-based adhesives, cellulose-based adhesives, and polyester-based adhesives. These adhesives may be used alone or in combination of two or more.

[0030] The first layer 10 functions as a light coupling layer (light extraction layer) by arranging the first regions 12 and the second regions 14 in a predetermined pattern. The light 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.

[0031] The optical element 100 having the above-described configuration functions as follows.

[0032] 1 shows the X direction, Y direction, and Z direction, which are orthogonal to one another. Here, each layer of the optical element 100 has a main surface 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 40 by the first layer 10, the second layer 20, and the third layer 30, and is output in the Z direction (output light L ＥOf course, the propagation direction of light has variations (distribution) from the Y direction, and the emission direction of light also has variations (distribution) from the Z direction.

[0033] Light L propagating in the light guide layer 50 Ｐ Of these, light incident on the interface between the second layer 20 and the first region 12 of the first layer 10 is totally internally reflected. In contrast, light incident on the interface between the second layer 20 and the second region 14 of the first layer 10 passes through the second region 14 of the first layer 10, the third layer 30, and the base layer 40 without being totally internally reflected, and is emitted from the optical element 100.

[0034] The light distribution (e.g., output intensity distribution, output angle distribution) of light extracted from the light guide layer 50 (coupled with the base layer 40) by the optical element 1 can be controlled by adjusting the arrangement of the first region 12 and the second region 14 of the first layer 10 within the layer surface (a plane parallel to the XY plane). The arrangement of the first region 12 and the second region 14 in the first layer 10 is set appropriately according to the required light distribution.

[0035] 2 is a diagram showing an example of the arrangement of the first regions 12 and the second regions 14 in the first layer 10. In the example shown in FIG. 2, a plurality of circular second regions 14 are discretely arranged in the first layer 10. The diameter of the second regions 14 is, for example, not less than about 1 μm and not more than about 1000 μm. Furthermore, the pitch Px of the second regions 14 adjacent in the X direction and the pitch Py of the second regions 14 adjacent in the Y direction are each 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 the second regions 14 adjacent in the X direction and the Y direction, respectively.

[0036] The arrangement of the first regions 12 and the second regions 14 in the first layer 10 can be modified in various ways. In addition, the shape of the second regions 14 is not limited to the circular shape shown as an example, and can be various shapes.

[0037] 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 1 (optical element 100). 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, when the second region 14 is circular as shown in FIG. 2, the diameter of the circle is preferably 100 μm or less. By having the major axis of the second region 14 be 100 μm or less, it is possible to prevent the second region 14 from being visible in applications where devices including the optical member 1 are viewed from a relatively close distance, such as mobile displays and small signage. When the second region 14 is not circular, the dimensions of the second region 14 can be evaluated, for example, by the diameter of an isocircular ellipse.

[0038] The optical member (and optical element having the same) manufactured by the manufacturing method according to the embodiment of the present invention may include at least the first layer 10 described above, and various modifications are possible.

[0039] Fig. 3 shows another optical element 200 having an optical member manufactured by a manufacturing method according to an embodiment of the present invention. The optical element 200 shown in Fig. 3 differs from the optical element 100 shown in Fig. 1 in that the optical element 200 further has a light distribution control structure having a plurality of internal spaces IS.

[0040] In the illustrated example, the light distribution control structure having a plurality of internal spaces IS is formed in a direction changing layer 70 provided on a base layer 40. The direction changing layer 70 is composed of a shaped film 72 having a main surface with a plurality of recesses 74, and an adhesive layer 76 disposed between the shaped film 72 and the base layer 40. The plurality of internal spaces IS of the light distribution control structure are defined by the plurality of recesses 74 of the shaped film 72 and the adhesive layer 76, and form an interface that directs a portion of the light propagating within the base layer 40 toward the light output surface by total internal reflection (TIR).

[0041] [Method for Manufacturing Optical Member] A method for manufacturing the optical member 1 according to an embodiment of the present invention will be described.

[0042] A manufacturing method according to an embodiment of the present invention includes step A of preparing a porous layer supported on a substrate, step B of removing a partial region of the porous layer by irradiating the porous layer with laser light, the removed partial region including a plurality of discrete island regions, and step C of disposing a first adhesive layer on the porous layer after step B. According to the manufacturing method according to an embodiment of the present invention, an optical element having an optical coupling layer (light extraction layer) capable of extracting light with sufficiently high directionality can be manufactured, as will be described later.

[0043] The manufacturing method according to an embodiment of the present invention may further include, after step C, step D of peeling the substrate from the porous layer, and, after step D, step E of placing a second adhesive layer on the porous layer on the opposite side from the first adhesive layer.

[0044] 4A-4F, an example of a manufacturing method according to an embodiment of the present invention will be described.

[0045] First, as shown in FIG. 4A , a layer (porous layer) 10P having a porous structure is prepared and supported on a substrate 40T. For example, the porous layer 10P is formed on the substrate 40T. The substrate 40T may be a film formed from a resin. For example, a polyimide (PI) film or a black polyethylene terephthalate (PET) film may be used as the substrate 40T. The porous layer 10P may be formed, for example, by a method exemplified below.

[0046] In the illustrated example, a release layer 2 is provided on the substrate 40T, and the porous layer 10P is formed on the release layer 2. The release layer 2 is formed from a material (e.g., cycloolefin polymer) that has high releasability for the porous layer 10P. The release layer 2 may be provided with laser light absorbency. The release layer 2 may also be omitted. The presence of the release layer 2 makes it easier to transfer the porous layer 10P (the step shown in FIG. 4E), which will be described later, (i.e., improves the releasability of the porous layer 10P).

[0047] The thickness of the release layer 2 is, for example, 1000 nm or less. However, if the release layer 2 is relatively thick, cracks may occur in the porous layer 10P in the subsequent step of irradiating the porous layer 10P with laser light. From the viewpoint of suppressing cracks in the porous layer 10P, the thickness of the release layer 2 is preferably 500 nm or less, more preferably 250 nm or less, and even more preferably 200 nm or less. Note that if a material that easily peels off the porous layer 10P (e.g., polyimide) is used as the material of the substrate 40T, the release layer 2 may be omitted.

[0048] The release layer 2 preferably comprises, as its main component, a polymer that does not contain polar groups (hereinafter also referred to as a "non-polar polymer"). "Does not contain polar groups" means that the polymer does not contain polar groups in its main chain skeleton or side chain skeleton, excluding the main chain terminals. The main chain terminals of the polymer may contain polar groups derived from an initiator or quencher. Furthermore, "composed primarily of a polymer that does not contain polar groups" means that the release layer 2 contains 50% or more of the non-polar polymer. The release layer 2 preferably contains 80% or more of the non-polar polymer. Examples of non-polar polymers include polyolefin-based polymers, cycloolefin-based polymers such as polynorbornene-based polymers, and polystyrene-based polymers. Among these, cycloolefin-based polymers and polyolefin-based polymers are preferred, with cycloolefin-based polymers being particularly preferred.

[0049] 4B , laser light LB is applied to the porous layer 10P to remove (peel off) a portion of the porous layer 10P. That is, in this step, the porous layer 10P is partially removed by the laser lift-off method. At this time, the removed portion includes a plurality of discrete island regions 10a.

[0050] An ultraviolet laser beam can be suitably used as the laser beam LB. Laser beams other than ultraviolet laser beams (e.g., infrared laser beams) can also be used, but the use of ultraviolet laser beams allows for the removal of the porous layer 10P even in fine patterns. The wavelength range of the ultraviolet laser beam is preferably 150 nm or more and 380 nm or less, and more preferably 190 nm or more and 360 nm or less. For example, laser beams with wavelengths of 193 nm, 248 nm, 308 nm, and 351 nm can be obtained from an ArF excimer laser light source, a KrF excimer laser light source, a XeCL excimer laser light source, and a XeF excimer laser light source, respectively.

[0051] The amount of light irradiation required to remove the porous layer 10P can be appropriately set by adjusting the intensity of the irradiated light, the irradiation time, etc. In addition, the removal of the porous layer 10P can be suitably performed by appropriately setting the absorption coefficient of the substrate 40T according to the wavelength range of the laser light LB used. Specifically, when the absorption coefficient of the substrate 40T for the laser light LB used is 500 cm －１ For example, when ultraviolet laser light having a wavelength of 355 nm is used as the laser light LB, the absorption coefficient of the substrate 40T for light having a wavelength of 355 nm is 500 cm －１ It is preferable that the thickness of the substrate 40T is L, and the light intensity obtained by subtracting the intensity of the reflected light from the intensity of the incident light is I. ０ , the intensity of light after passing through the substrate 40T is I, the absorption coefficient α is −αL = log １０ (I / I ０ ) relationship (derived from the Beer-Lambert equation).

[0052] When using ultraviolet laser light, from the viewpoint of improving processing efficiency and productivity, it is necessary to set the absorption coefficient of the substrate 40T for the ultraviolet laser light to 1000 cm －１ As the material of the substrate 40T, for example, polyethylene naphthalate (PEN) and polyimide can be suitably used, and from the viewpoint of cost, polyethylene naphthalate can be particularly suitably used.

[0053] The light intensity distribution of the laser light (beam) LB is, for example, a Gaussian type or a top hat type. When the light intensity distribution of the laser light LB is a top hat type, it is easy to make the energy provided by irradiation of the laser light LB uniform within the irradiation region.

[0054] The beam shape may be circular or rectangular. The beam may be focused using a focusing optical system such as an objective lens. When the beam shape is circular, the focal diameter (spot diameter) is preferably in the range of 1 μm to 200 μm, more preferably 20 μm to 120 μm.

[0055] From the viewpoint of forming a pattern in a short time, it is preferable to use a pulsed laser, and it is preferable to use a laser having a pulse width on the order of nanoseconds to microseconds. The repetition frequency of the pulsed laser light is not particularly limited, but from the viewpoint of productivity, the higher the repetition frequency, the better, and it can be appropriately adjusted within the range of 10 kHz to 5000 kHz.

[0056] The types of laser oscillators that satisfy the above requirements include excimer lasers, YAG lasers, YLF lasers, and YVO ４ Examples of such lasers include lasers, fiber lasers, and semiconductor lasers.

[0057] The irradiation conditions of the laser beam LB can be set to any appropriate conditions, but the energy density is, for example, 0.1 J / cm ２ 5J / cm or more ２ It is preferable that:

[0058] From the viewpoint of performing the desired pattern processing at high speed, it is preferable to use a scanner unit that uses a galvanometer scanner, a polygon scanner, or a combination of these. By using such a scanner unit, it is possible to form a pattern at a scan speed in the scanning direction of the laser light in the range of 0.01 m / s to 170 m / s. The pattern pitch can be set arbitrarily by adjusting the repetition frequency of the laser pulse in accordance with the scan speed, and can be set, for example, in the range of 10 μm to 500 μm.

[0059] The pattern pitch in the direction perpendicular to the scanning direction can be appropriately adjusted by controlling the relative positional relationship between the scanner unit and the object to be irradiated. Such control can be performed using a precision stage with a drive shaft, for example, by adsorbing and fixing a sheet of the object to be irradiated to the stage surface and irradiating it with laser light while feeding it at regular intervals in the direction perpendicular to the scanning direction, thereby forming a pattern at a desired pitch. Alternatively, a pattern can be formed using a scanner unit on a wound, long raw web that is being transported intermittently or continuously by a roll-to-roll transport method.

[0060] 4C, the first adhesive layer 20 is disposed on the porous layer 10P. Specifically, the first adhesive layer 20 formed on the release sheet 61 is attached onto the porous layer 10P.

[0061] 4D, the substrate 40T is peeled off from the porous layer 10P. In the example shown in the figure, the release layer 2 is formed on the substrate 40T, and therefore the substrate 40T is peeled off together with the release layer 2 from the porous layer 10P.

[0062] Next, as shown in FIG. 4E , a second adhesive layer 30 is placed on the side of the porous layer 10P opposite the first adhesive layer 20. Specifically, the second adhesive layer 30 formed on a release sheet 62 is attached to the first layer 10. At this time, the regions where the porous layer 10P remains become the first regions 12. Furthermore, the adhesive from the first adhesive layer 20 penetrates into the multiple island regions 10a from which the porous layer 10P has been removed in the step shown in FIG. 4C and / or the adhesive from the second adhesive layer 30 penetrates into the multiple island regions 10a in the step shown in FIG. 4E , thereby forming the second regions 14. In this manner, the first layer 10 including the first regions 12 and the second regions 14 is obtained. A barrier layer may be provided between the porous layer 10P and the first adhesive layer 20 and / or between the porous layer 10P and the second adhesive layer 30 to prevent the adhesive component from penetrating into the porous layer 10P.

[0063] 4F , the release sheet 62 is then peeled off, and the base layer 40 is attached to the second adhesive layer 30, thereby obtaining the optical member 1. After that, the release sheet 61 is peeled off, and the light guide layer 50 is attached to the first adhesive layer 20, thereby obtaining the optical element 100.

[0064] Here, we have described an example in which the substrate 40T is peeled from the porous layer 10P (in other words, the porous layer 10P is transferred from the substrate 40T to a laminate of the release sheet 61 and the first adhesive layer 20). However, the substrate 40T may function as part of the optical member (optical element) without being peeled from the porous layer 10P (i.e., without functioning as a transfer substrate). In this case, in the step shown in FIG. 4C , the plurality of island regions 10a may be completely filled with adhesive from the first adhesive layer 20. Furthermore, if the substrate 40T is not peeled from the porous layer 10P, a second adhesive layer 30 may be laminated on the side of the substrate 40T opposite the porous layer 10P. When the manufacturing method according to an embodiment of the present invention includes step D of peeling the substrate 40T from the porous layer 10P, the thickness of the optical member (optical element) can be reduced by the amount of the substrate 40T remaining, compared to when the substrate 40T is not peeled from the porous layer 10P.

[0065] According to the above-described manufacturing method (including at least steps A, B, and C), an optical element having a light coupling layer (light extraction layer) capable of extracting light with sufficiently high directivity can be manufactured. The results of verifying this are explained below with reference to Examples 1 to 6, a Reference Example, and a Comparative Example.

[0066] Example 1 (1) Preparation of Substrate and Formation of Release Layer A 50 μm thick black PET film (Lumirror X30 manufactured by Toray Industries, Inc.) was prepared as the substrate 40T, and a release layer 2 was formed thereon as follows.

[0067] The coating liquid for forming the release layer 2 (release layer-forming coating liquid) was prepared by adding cycloolefin polymer (COP) (ZEONEX F52R manufactured by Zeon Corporation) to ethylcyclohexane so that the concentration was 8 mass %, and stirring and mixing was performed at room temperature with a stirrer until the COP was dissolved visually. In addition, one side of the black PET film was subjected to corona treatment (discharge intensity 0.22 W / cm) in order to prevent the release layer-forming coating liquid from being repelled. ２ The release layer-forming coating liquid was applied to the corona-treated surface of the black PET film, and then dried at 120°C for 3 minutes to form a release layer 2 having a thickness of 230 nm. The thickness of the release layer 2 was measured using a microspectrophotometer (the same was true for the other examples).

[0068] (2) Formation of Porous Layer A coating liquid for forming the porous layer 10P (first region 12 of the first layer 10) was prepared as follows.

[0069] (2-1) Gelation of Silicon Compounds 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 a mixed solution A. 0.5 g of a 0.01 mol / L aqueous solution of oxalic acid was added to this mixed solution A, and the mixture was stirred at room temperature for 30 minutes to hydrolyze the MTMS, producing a mixed solution B containing tris(hydroxy)methylsilane.

[0070] 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).

[0071] (2-2) 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.

[0072] (2-3) 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 Co., Ltd.: trade name UH-50). 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 at 50 W and 20 kHz.

[0073] This grinding process pulverized the gel-like silicon compound in Mixture D, resulting in Mixture D' becoming a sol of the pulverized material. The volume average particle size, which indicates the particle size variation of the pulverized material contained in Mixture D', was measured using a dynamic light scattering Nanotrac particle size analyzer (UPA-EX150, manufactured by Nikkiso Co., Ltd.) and found to be 0.50 to 0.70. Furthermore, to 0.75 g of this sol (Mixture 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 solution for forming a porous layer. The coating solution for forming a porous layer contains a porous silica material having silsesquioxane as its basic structure.

[0074] The porous layer-forming coating liquid was applied onto the release layer 2 so that the thickness of the coating film after drying would be 700 nm, forming a coating film. The coating film was left to stand for 1 minute and then dried at 100°C for 2 minutes. The dried coating film was irradiated with light of 360 nm at 300 mJ / cm. ２ The black PET film was then exposed to UV light at a light exposure (energy) of 1.00 to obtain a laminate in which a release layer 2 and a porous layer 10P (a porous silica material formed by chemical bonding between microporous silica particles) were formed on the black PET film. The refractive index of the porous layer 10P was 1.15.

[0075] (3) Partial Removal of Porous Layer by Laser Lift-Off Method The obtained laminate was irradiated with ultraviolet laser light under the following conditions to remove some regions (multiple island regions) of the porous layer 10P. Laser oscillator: Talon 355-20 manufactured by Spectra-Physics Wavelength: 355 nm Scanner: IntelliScan 14 (galvanometer scanner) manufactured by ScanLab Beam intensity distribution: Gaussian Focused spot size: φ80 μm Repetition frequency: 12.5 kHz Pattern pitch: 200 μm Pattern processing area: □100 mm Scan speed: 2.5 m / s Power: 0.913 W Pulse energy: 73 μJ

[0076] (4) Fabrication of Optical Element An optical element having a configuration similar to that of the optical element 200 shown in FIG. 3 was fabricated using a laminate in which the porous layer 10P had been partially removed as described above. The second layer (first adhesive layer) 20 and the third layer (second adhesive layer) 30 were formed to a thickness of 10 μm using an acrylic adhesive. A film made of an acrylic resin was used as the base layer 40, and the adhesive layer 76 (adhesive layer bonding the base layer 40 and the shaped film 72) constituting the direction conversion layer 70 was formed using a polyester adhesive.

[0077] The second regions 14 of the first layer 10 were substantially circular (diameter: approximately 93 μm). The area ratio (design value) of the second regions 14 to the first layer 10 was 17.0%.

[0078] As the shaped film 72, a concave-convex shaped film was produced according to the method described in JP-A-2013-524288. Specifically, the surface of a polymethyl methacrylate (PMMA) film was coated with lacquer (Finecure RM-64 manufactured by Sanyo Chemical Industries, Ltd.), an optical pattern was embossed on the film surface containing the lacquer, and then the lacquer was cured to produce a concave-convex shaped film. The total thickness of the concave-convex shaped film was 130 μm, and the haze value was 0.8%.

[0079] 5A and 5B show a portion of the produced unevenly shaped film 72. FIG. 5A is a plan view of the unevenly shaped film 72 as seen from the main surface (uneven surface) having a plurality of recesses 74, and FIG. 5B is a cross-sectional view taken along line 5B-5B' in FIG. 5A. The arrangement interval E of the plurality of recesses 74 in the X direction was 155 μm, and the arrangement interval D in the Y direction was 100 μm. The cross section of each recess 74 was triangular, and the length L of each recess 74 was 80 μm, the width W was 14 μm, and the depth H was 10 μm. The density of the recesses 74 on the surface of the unevenly shaped film 72 was 3612 / cm ２ The angles θa and θb in FIG. 5B were both 41°, and the occupied area ratio of the recesses 74 when the unevenness-forming film 72 was viewed in plan from the uneven surface side was 4.05%.

[0080] [Example 2] A 50 μm thick PI film (Kapton H200 manufactured by DuPont-Toray Co., Ltd.) was prepared as the substrate 40T, and a porous layer 10P was formed thereon in the same manner as in Example 1 without forming a release layer 2. The obtained laminate was irradiated with ultraviolet laser light under the following conditions to remove some regions (multiple island regions) of the porous layer 10P. Laser oscillator: Talon 355-20 manufactured by Spectra-Physics Wavelength: 355 nm Scanner: IntelliScan 14 (galvanometer scanner) manufactured by ScanLab Beam intensity distribution: Gaussian Focused spot size: φ80 μm Repetition frequency: 12.5 kHz Pattern pitch: 200 μm Pattern processing area: □100 mm Scan speed: 2.5 m / s Power: 0.375 W Pulse energy: 30 μJ

[0081] Using the laminate from which the porous layer 10P had been partially removed as described above, an optical element was fabricated in the same manner as in Example 1. The second region 14 of the first layer 10 was substantially circular (diameter: approximately 82 μm). The area ratio (design value) of the second region 14 to the first layer 10 was 13.2%.

[0082] [Example 3] A laminate having a release layer 2 and a porous layer 10P formed on a substrate 40T was obtained in the same manner as in Example 1. The obtained laminate was irradiated with ultraviolet laser light under the following conditions to remove some regions (multiple island regions) of the porous layer 10P. Laser oscillator: Talon 355-20 manufactured by Spectra-Physics Wavelength: 355 nm Scanner: LSE 310 (polygon scanner) manufactured by Next Scan Technology Beam intensity distribution: Gaussian Focused spot size: φ80 μm Repetition frequency: 200 kHz Pattern pitch: 200 μm Pattern processing area: □100 mm Scan speed: 40 m / s Power: 14.6 W Pulse energy: 73 μJ

[0083] Using the laminate from which the porous layer 10P had been partially removed as described above, an optical element was fabricated in the same manner as in Example 1. The second region 14 of the first layer 10 was substantially circular (diameter: approximately 90 μm). The area ratio (design value) occupied by the second region 14 in the first layer 10 was 15.9%.

[0084] [Example 4] A laminate having a release layer 2 and a porous layer 10P formed on a substrate 40T was obtained in the same manner as in Example 1. The obtained laminate was irradiated with infrared laser light under the following conditions to remove some regions (multiple island regions) of the porous layer 10P. Laser oscillator: SPI redENERGY G4 Wavelength: 1060 nm Scanner: Next Scan Technology LSE310 (polygon scanner) Beam intensity distribution: Gaussian Focused spot size: φ80 μm Repetition frequency: 500 kHz Pattern pitch: 200 μm Pattern processing area: □100 mm Scan speed: 100 m / s Power: 55 W Pulse energy: 110 μJ

[0085] Using the laminate from which the porous layer 10P had been partially removed as described above, an optical element was fabricated in the same manner as in Example 1. The second region 14 of the first layer 10 was substantially circular (diameter: approximately 102 μm). The area ratio (design value) of the second region 14 to the first layer 10 was 20.4%.

[0086] [Example 5] A laminate in which a release layer 2 and a porous layer 10P were formed on a substrate 40T was obtained in the same manner as in Example 1. The obtained laminate was irradiated with ultraviolet laser light under the same conditions as in Example 1 to remove some regions (multiple island regions) of the porous layer 10P.

[0087] An optical element was fabricated in substantially the same manner as in Example 1 using a laminate in which the porous layer 10P had been partially removed as described above. However, the thicknesses of the second layer (first adhesive layer) 20 and the third layer (second adhesive layer) 30 were each 17 μm. The second region 14 of the first layer 10 was substantially circular (diameter: approximately 95 μm). The area ratio (design value) occupied by the second region 14 in the first layer 10 was 17.7%.

[0088] [Example 6] A 30 μm thick acrylic resin film was prepared as the substrate 40T, and a porous layer 10P was formed thereon in the same manner as in Example 2. The resulting laminate was irradiated with ultraviolet laser light under the following conditions to remove some regions (multiple island regions) of the porous layer 10P. Laser oscillator: Mlase excimer laser Wavelength: 193 nm Scanner: Laser fixed and XY stage controlled Beam intensity distribution: Top hat Focused spot size: φ100 μm Repetition frequency: 0.1 kHz Pattern pitch: 150 μm Pattern processing area: □100 mm Scan speed: 0.015 m / s Power: 0.001 W Pulse energy: 12 μJ

[0089] An optical element was fabricated in a manner substantially similar to Example 1 using a laminate from which the porous layer 10P had been partially removed as described above. However, the substrate 40T was not peeled off from the porous layer 10P, and the substrate 40T served as the substrate layer 40. The third layer (second adhesive layer) 30 was omitted. The second region 14 of the first layer 10 was substantially circular (diameter approximately 100 μm). The area ratio (design value) occupied by the second region 14 in the first layer 10 was 19.6%.

[0090] [Reference Example] The optical member disclosed in International Publication No. 2022 / 071165 by the present applicant was produced as follows.

[0091] (1) Configuration of Optical Element FIG. 6 shows the configuration of an optical element 801 of a reference example. The optical element 801 shown in FIG. 6 includes a first layer 810 having a porous structure and a second layer 820 adjacent to the first layer 810 in the layer normal direction. The second layer 820 contains a resin composition and has a transmittance of 5% to 85% for light (near-infrared) in a wavelength range of more than 800 nm and less than 2000 nm. The first layer 810 includes a first region 812 having a porous structure and a second region 814 in which voids in the porous structure are filled with a resin composition. The second layer 820 has adhesive properties. The optical element 801 further includes a substrate layer 840 supporting the first layer 810 and a release sheet 861 disposed on the second layer 820 opposite the first layer 810.

[0092] When manufacturing the optical member 801, first, as shown in the upper part of FIG. 7 , a laminate is prepared in which a porous layer 810P having a porous structure that will become the first layer 810, an infrared-absorbing resin composition layer 820P that will become the second layer 820, and a release sheet 861 are laminated on a base layer 840. This laminate can be obtained, for example, by superimposing a first laminate in which the porous layer 810P is formed on the base layer 840 and a second laminate in which the infrared-absorbing resin composition layer 820P is formed on the release sheet 861. Next, as shown in the lower part of FIG. 7 , near-infrared rays IL are selectively irradiated to a portion of the infrared-absorbing resin composition layer 820P. Because the infrared-absorbing resin composition layer 820P absorbs near-infrared rays IL, the resin composition in the region irradiated with the near-infrared rays IL is melted, and the resin composition is selectively filled into the voids in the porous structure of the porous layer 810P. As a result, the first region 812, which is not filled with the resin composition, has a smaller refractive index than the second region 814, in which the voids in the porous structure are filled with the resin composition.

[0093] (2) Preparation of First Laminate A coating liquid for forming a porous layer (first region 812 of first layer 810) was prepared in the same manner as in Example 1. The obtained coating liquid was applied to 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 at 100°C for 1 minute, and the dried coating film was irradiated with 300 mJ / cm using light with a wavelength of 360 nm. ２ The resultant acrylic resin film (substrate layer 840) was then subjected to UV irradiation at a light irradiation dose (energy) of 1.15 to obtain a first laminate (acrylic film with a porous silica layer) in which a porous layer (a porous silica body formed by chemical bonding between microporous silica particles) 810P was formed on the acrylic resin film (substrate layer 840). The refractive index of the porous layer 10P was 1.15.

[0094] (3) Preparation of Second Laminate The infrared absorbing resin composition layer 820P used was a laminate structure of an adhesive layer (resin composition layer) containing no dye and a dye layer formed on the adhesive layer. ２ 0, mass ratio 1:9:1), 0.2 parts by mass of a dye-based colorant CIR-RL (phenylenediamine-based diimonium compound) manufactured by Nippon Carlit Co., Ltd. was added to prepare a colorant solution.

[0095] One separator of double-sided PSA A (PET separator / acrylic PSA A / PET separator, thickness 38 μm / 10 μm / 38 μm) produced by the method disclosed in paragraphs

[0139] to

[0141] of WO 2022 / 071165 was peeled off, and the above dye solution was applied to the exposed surface of the acrylic PSA, forming a film with a wet thickness of 33 μm. The film was then placed in a heating oven set at 100 ° C. for 2 minutes to dry, obtaining a dye layer. The transmittance of the laminate of the optical adhesive layer and the dye layer to laser light with a wavelength of 1064 nm was 49%.

[0096] (4) Preparation of Optical Members and Optical Elements The second laminate was attached to the main surface of the porous layer 810P of the first laminate, and the laminate was cut to a size of 100 mm to obtain a test piece for preparing an optical member.

[0097] The obtained test piece was fixed to a vacuum suction stage and irradiated with near-infrared laser light under the following conditions to produce an optical member 801. Laser oscillator: JenLas fiber ns20 manufactured by Jenoptik, Wavelength: 1064 nm, Objective lens: fθ lens (f82 mm), Scanner: IntelliScan 14 (galvanometer scanner) manufactured by ScanLab, Beam intensity distribution: Gaussian, Spot size: φ60 μm, Repetition frequency: 12.5 kHz, Scan speed: 2.5 m / s, Pattern pitch: 200 μm, Pattern processing area: □100 mm, Power: 5.6 W, Pulse energy: 448 μJ

[0098] The optical element 800 shown in FIG. 8 was fabricated using the resulting optical member 801. The optical element 800 was fabricated by peeling off the release sheet 861 from the optical member 801, attaching the light-guiding layer 850 to the second layer 820, and disposing a direction-changing layer 870 including multiple internal spaces IS on the opposite side of the base layer 840 from the first layer 810 (specifically, attaching a shaped film 872 to the base layer 840 via an adhesive layer 876). The adhesive layer 876 was formed using a polyester adhesive. The shaped film 872 having multiple recesses 874 was manufactured in the same manner as the shaped film 72 used in Example 1. The second region 814 of the first layer 810 was approximately circular (diameter approximately 50 μm). The area ratio (design value) occupied by the second region 814 in the first layer 810 was 4.9%.

[0099] Comparative Example An optical member 901 shown in FIG. 9 was produced using the inkjet method as disclosed in Patent Document 1.

[0100] (1) Structure of the Optical Element The optical element 901 shown in FIG. 9 includes a first layer 910 having a porous structure, a second layer 920 adjacent to the first layer 910 in the layer normal direction, and a base layer 940 supporting the first layer 910.

[0101] The first layer 910 includes a first region 912 having a porous structure and a second region 914 in which voids in the porous structure are filled with a resin composition. The second layer 920 is a layer containing a resin composition, and more specifically, is a pressure-sensitive adhesive layer.

[0102] 10A, a first laminate is prepared in which a porous layer 910P having a porous structure that will become a first layer 910 is formed on a base layer 940. Also, as shown in FIG. 10B, a second laminate is prepared in which a resin pattern layer 902 including a plurality of discrete island regions 902a is formed on a second layer (pressure-sensitive adhesive layer) 920 by an inkjet method using a photocurable resin composition.

[0103] 10C , the first laminate and the second laminate are superimposed so that the resin pattern layer 902 is adjacent to the porous layer 910P, and then, as shown in the lower part of Fig. 10C , the photocurable resin composition of the resin pattern layer 902 is infiltrated into the voids of the porous layer 910P and photocured, thereby obtaining an optical element 901 including a first layer 910 in which first regions 912 not filled with the resin composition and second regions 914 in which the voids of the porous structure are filled with the resin composition are arranged in a predetermined pattern.

[0104] (2) Preparation of First Laminate In the same manner as in the reference example, a first laminate (acrylic film with a silica porous layer) was obtained in which a porous layer 910P was formed on an acrylic resin film as a base layer 940.

[0105] (3) Preparation of Second Laminate A pressure-sensitive adhesive layer 920 was formed on a release-treated PET film using an acrylic pressure-sensitive adhesive. The pressure-sensitive adhesive layer 920 had a thickness of 10 μm and a refractive index of 1.47. A resin pattern layer 902 was formed on the pressure-sensitive adhesive layer 920 by dropping an epoxy monomer mixture adjusted to a concentration of 25% as ink using an inkjet device (product name PIJIL-HV) manufactured by Cluster Technology Co., Ltd., at the same pattern pitch as in Examples 1 to 5.

[0106] (4) Fabrication of Optical Members and Optical Elements The first laminate and the second laminate were superimposed so that the resin pattern layer 902 was adjacent to the porous layer 910P, and the photocurable resin composition of the resin pattern layer 902 was allowed to penetrate into the voids of the porous layer 10P. Next, ultraviolet light was irradiated from the first laminate side at an irradiation dose of 600 mJ, and then the laminate was stored in a dryer at 60°C for 20 hours.

[0107] The optical element 900 shown in FIG. 11 was produced using the obtained optical member 901. The optical element 900 was produced by peeling off the PET film from the optical member 901, attaching a light-guiding layer 950 to the second layer 920, and arranging a direction-changing layer 970 including multiple internal spaces IS on the opposite side of the base layer 940 from the first layer 910 (specifically, attaching a shaped film 972 to the base layer 940 via an adhesive layer 976). The adhesive layer 976 was formed using a polyester adhesive. The shaped film 972 having multiple recesses 974 was produced in the same manner as the shaped film 72 used in Example 1. The second region 914 of the first layer 910 was approximately circular (diameter approximately 66 μm). The area ratio (design value) occupied by the second region 914 in the first layer 910 was 8.6%.

[0108] [Evaluation of Light Distribution Characteristics] The light distribution characteristics were evaluated for Examples 1 to 6, Reference Example, and Comparative Example. An LED light source was installed at the end of the light guide layer, and light was incident from the end of the light guide layer into the optical element, and the light was extracted from the shaped film side. The luminance distribution (relationship between light output angle and luminance) was measured from the extracted light using an imaging colorimeter (ProMetric I-Plus manufactured by RADIANT). The size of the measurement area was 35 mm square (the same as the size of the detector lens). The peak angle and half-value angle were calculated from the measured luminance distribution. The peak angle is the angle at which luminance is maximized and can be considered an indicator of whether light is extracted in the front direction. The half-value angle (full width at half maximum) is the angular range from maximum luminance to half of that, and can be considered an indicator of how widely the extracted light is spread.

[0109] The evaluation results are shown in Table 1. In the "Light distribution characteristic evaluation" column in Table 1, cases where the peak angle was within ±15° and the half-value angle was 35° or less were rated "OK", and other cases were rated "NG".

[0110]

[0111] As can be seen from Table 1, it was confirmed that the peak angle was within ±15° and the half-value angle was 35° or less in all of Examples 1 to 6, and that light with high directivity was extracted in the front direction. In contrast, in the Reference Example and Comparative Example, the peak angle was not within ±15° and the half-value angle was more than 35°.

[0112] As described above, it has been confirmed that the manufacturing method according to the embodiment of the present invention can provide an optical element having a light coupling layer (light extraction layer) capable of extracting light with sufficiently high directivity. The reason why the embodiment of the present invention can improve the directivity of the extracted light is presumed as follows.

[0113] In the optical member 801 of the reference example, the second region 814 of the first layer 810 contains a mixture of a porous structure and a resin composition. Similarly, in the optical member 901 of the comparative example, the second region 914 of the first layer 910 contains a mixture of a porous structure and a resin composition. In contrast, in the optical member 1 obtained by the manufacturing method according to an embodiment of the present invention, the second region 14 of the first layer 10 does not have a porous structure, and substantially only adhesive is present in the second region 14. This is thought to suppress scattering (diffusion) around the second region 14, contributing to improved directionality.

[0114] Fig. 12 shows an optical microscope image of the optical element of the comparative example, and Fig. 13 shows an optical microscope image of the optical element of Example 1. As shown in Figs. 12 and 13, there is a white area due to light scattering around the nearly circular second region. If light is scattered, the desired light distribution characteristics may not be obtained, so it is preferable that the area of ​​the white area described above is small. Comparing Figs. 12 and 13 shows that the area of ​​the white area is smaller in Example 1 than in the comparative example, and scattering around the second region is suppressed.

[0115] As already mentioned, cracks may occur in the porous layer 10 P during the process of irradiating the porous layer 10 P with laser light. These phenomena will now be described in more detail.

[0116] As a result of examining the various conditions of the manufacturing method according to an embodiment of the present invention, the inventors of the present invention found that when the porous layer 10P is partially removed by the laser lift-off method, cracks may occur in the remaining porous layer 10P.

[0117] Fig. 14 shows an optical microscope image of an optical element having cracks in the porous layer 10P, and Fig. 15 shows an optical microscope image of an optical element having no cracks in the porous layer 10P. In the example shown in Fig. 14, radial cracks have occurred around the periphery of the nearly circular second region 14. In contrast, in the example shown in Fig. 15, no such cracks have occurred around the periphery of the second region 14. Cracks in the porous layer 10P can cause a deterioration in appearance and light directionality.

[0118] As a result of further detailed investigations, the inventors of the present application found that the likelihood of cracking in porous layer 10P is correlated with the thickness of release layer 2. Specifically, it was found that the thicker the release layer 2, the more likely the porous layer 10P is to crack (conversely, the thinner the release layer 2, the less likely the porous layer 10P is to crack).

[0119] The principle behind the occurrence of cracks in the porous layer 10P is presumed to be as follows. Figures 16 and 17 are diagrams for explaining the principle behind the occurrence of cracks in the porous layer 10P, and show how a part of the porous layer 10P is peeled off together with the release layer 2 by irradiation with laser light LB. Figure 16 shows the case where the release layer 2 is relatively thick, and Figure 17 shows the case where the release layer 2 is relatively thin.

[0120] When the porous layer 10P is partially removed by the laser lift-off method, the substrate 40T reacts with the laser light LB and explodes near the interface with the release layer 2, and the force of the explosion physically removes the release layer 2 and the porous layer 10P.

[0121] 16, if the release layer 2 is relatively thick, the force of the explosion of the substrate 40T may not be sufficient to peel off the release layer 2, and as a result, a region CR where the release layer 2 and the porous layer 10P are beginning to peel off (floating up from the substrate 40T) may be formed around the region (island region 10a) where the porous layer 10P has been removed. In such a region CR, cracks occur in the porous layer 10P.

[0122] 17, when the release layer 2 is relatively thin, the force of the explosion of the substrate 40T is often sufficient to peel off the release layer 2, and therefore, a region CR where the release layer 2 and the porous layer 10P are about to peel off (floating up from the substrate 40T) is unlikely to form around the region (island region 10a) where the porous layer 10P has been removed. Therefore, cracks in the porous layer 10P are unlikely to occur.

[0123] In this way, cracking of the porous layer 10P can be suppressed by setting the thickness of the release layer 2 to a relatively small value. As already described, the thickness of the release layer 2 is preferably 500 nm or less, more preferably 250 nm or less, and even more preferably 200 nm or less.

[0124] Here, the results of examining the susceptibility of the porous layer 10P to cracking will be explained using Examples 7 to 9 in addition to Examples 1, 2 and 4 already described.

[0125] Example 7: A 50 μm thick PEN film (Q51 manufactured by Toyobo Co., Ltd.) was prepared as the substrate 40T. A 144 nm thick release layer 2 was formed on the substrate 40T in the same manner as in Example 1, except that ZEONEX T62R manufactured by Zeon Corporation was used as the COP. A porous layer 10P was formed on the release layer 2 in the same manner as in Example 1, and the resulting laminate was irradiated with ultraviolet laser light under the following conditions to remove partial regions (multiple island-shaped regions) of the porous layer 10P. An optical element was fabricated in the same manner as in Example 1 using the laminate from which the porous layer 10P had been partially removed. The second region 14 of the first layer 10 was approximately circular (diameter approximately 93 μm). The area ratio (design value) occupied by the second region 14 in the first layer 10 was 17.0%. Laser oscillator: Talon 355-20 manufactured by Spectra-Physics Wavelength: 355 nm Scanner: IntelliScan 14 (galvanometer scanner) manufactured by ScanLab Beam intensity distribution: Gaussian Focused spot size: φ80 μm Repetition frequency: 50 kHz Pattern pitch: 200 μm Power: 2.0 W Pulse energy: 40 μJ

[0126] Example 8 An optical element was fabricated in the same manner as in Example 7, except that the thickness of the release layer 2 was 414 nm. The second region 14 of the first layer 10 was substantially circular (diameter: approximately 91 μm). The area ratio (design value) of the second region 14 to the first layer 10 was 16.3%.

[0127] Example 9 An optical element was fabricated in the same manner as in Example 7, except that the thickness of the release layer 2 was 583 nm. The second region 14 of the first layer 10 was substantially circular (diameter: approximately 97 μm). The area ratio (design value) of the second region 14 to the first layer 10 was 18.5%.

[0128] [Evaluation of cracks in porous layer 10P] Evaluation of cracks in the porous layer 10P was carried out for Examples 1, 2, 4, and 7 to 9. The evaluation of cracks was carried out by measuring the width of the region where cracks occurred in the porous layer 10P in an optical microscope image (the region outlined by a dotted line in FIG. 14). Cases where the width of the region where cracks occurred was less than 30 μm, 30 μm or more but less than 50 μm, 50 μm or more but less than 100 μm, and 100 μm or more were evaluated as "A," "B," "C," and "D," respectively.

[0129] The evaluation results of cracks in the porous layer 10P are shown in Table 2. Table 2 also shows the absorption coefficient of the substrate 40T and the thickness of the release layer 2 in each example.

[0130]

[0131] As can be seen from Table 2, with regard to cracking of the porous layer 10P, the ratings of Examples 1, 2, 4, and 8 ("B") were higher than the rating of Example 9 ("C"), and the rating of Example 7 ("A") was even higher. Thus, it was confirmed that the smaller the thickness of the release layer 2, the more cracking of the porous layer 10P was suppressed. Furthermore, in Example 1, an energy of 73 μJ was input to perform pattern processing of approximately 93 μm in diameter, whereas in Examples 7, 8, and 9, an energy of 40 μJ was input to perform pattern processing of approximately 90 μm in diameter. Thus, when the absorption coefficient of the substrate 40T for ultraviolet laser light is 1000 cm －１ From the above, it was confirmed that the processing efficiency was improved.

[0132] Next, examples of components that can be suitably used in the optical element according to the embodiment of the present invention will be described.

[0133] [Light Guide Layer] A wide variety of known light guide layers (light guides) can be used for the light guide layer 50. The light guide layer 50 is typically 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 are suitable for use include epoxy acrylate resins and urethane acrylate resins. These resins may be used alone or in combination.

[0134] The thickness of the light guide layer 50 can be, for example, 100 μm or more and 100 mm or less. The thickness of the light guide layer 50 is preferably 50 mm or less, more preferably 30 mm or less, and even more preferably 10 mm or less.

[0135] The refractive index n of the light guide layer 50 ＧＰ is, for example, the refractive index n ３ The lower limit is preferably 1.43 or more, and more preferably 1.47 or more. On the other hand, the upper limit of the refractive index of the light guide layer 50 is 1.7.

[0136] Although a conventional light guide layer having an uneven surface can be used as the light guide layer 50, 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 1 functioning as an optical coupling layer can have 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.

[0137] [Porous Layer, First Region of First Layer] The first region 12 of the first layer 10 has a porous structure. The first layer 10 can be formed from a porous layer 10P. Suitable porous layers 10P include substantially spherical particles such as silica particles, silica particles with micropores, hollow silica nanoparticles, fibrous particles such as cellulose nanofibers, alumina nanofibers, and silica nanofibers, and flat particles such as nanoclay composed of bentonite. In one embodiment, the porous layer 10P 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 10P 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 10P can be adjusted by the particle size and particle size distribution of the particles constituting the porous layer 10P.

[0138] Methods for obtaining the porous layer 10P 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.

[0139] A porous silica material can be suitably used as the porous layer 10P. The porous silica material can be produced by, for example, the following methods. Examples include a method of hydrolyzing and polycondensing silicon compounds; hydrolyzable silanes and / or silsesquioxanes, 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; and a method of using a pulverized gel in which a gel-like silicon compound obtained by a sol-gel method is pulverized and the resulting pulverized microporous particles are chemically bonded together using a catalyst or the like. However, the porous layer 10P 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 (RSiO １．５ , 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.

[0140] 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.

[0141] The lower limit of the thickness of the porous layer 10P (first layer 10) 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 10, but it is, for example, 5 μm or less, and more preferably 3 μm or less. If the thickness of the first layer 10 is within the above range, the surface irregularities will not be large enough to affect lamination, making it easy to combine or laminate with other materials.

[0142] The refractive index of the porous layer 10P, i.e., the refractive index n １ is preferably 1.30 or less. Total internal reflection is likely to occur at the interface in contact with the first region 12, that is, the critical angle can be made small. The refractive index n １ The refractive index n of the first region 12 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.

[0143] The lower limit of the porosity of the porous layer 10P, i.e., the porosity of the first region 12 of the first layer 10, 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 10P 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 12 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.

[0144] The film density of the porous layer 10P, i.e., the film density of the first region 12 of the first layer 10, 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 / cm３ 2.1g / cm or more ３ The film density can be measured by known methods.

[0145] The refractive index of the material constituting the matrix portion of the porous layer 10P (the portion other than the voids of the porous layer 10P) is n Ｍ Then, the refractive index of the porous layer 10P, i.e., the refractive index of the first region 12, n １ is n Ｍ For example, as described above, when a porous silica material is used as the porous layer 10P, n Ｍ is, for example, 1.41 or more and 1.43 or less.

[0146] [Second Region of First Layer] The second region 14 of the first layer 10 is formed by filling an adhesive in the region where the porous layer 10P has been removed. The refractive index n ２ is the refractive index n of the first region 12 １ and the refractive index n of the second layer 20 ３ and n １ <n ２ And n １ <n ３ The refractive index n of the second region 14 satisfies the relationship: ２ By satisfying this relationship, scattering of light due to reflection and refraction at the interface between the first region 12 and the second region 14 in the surface direction of the first layer 10 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.

[0147] When the adhesive from both the second layer 20 and the third layer 30 is filled into the region 10a from which the porous layer 10P has been removed, the second region 14 has a structure in which a region made of the adhesive from the second layer 20 and a region made of the adhesive from the third layer 30 are stacked along the thickness direction. From the viewpoint of suppressing reflection, refraction, etc. at the interface between the former region and the latter region, the refractive index n of the second layer 20 is ３ and the refractive index n of the third layer 30 ４ Specifically, the difference between the refractive index n３ and the refractive index n of the third layer 30 ４ The difference between is preferably 0.05 or less, more preferably 0.03 or less, and even more preferably 0.02 or less.

[0148] [Substrate Layer] The thickness of the substrate layer 40 is, for example, 1 μm to 1000 μm, preferably 10 μm to 100 μm, and more preferably 20 μm to 80 μm. The refractive index of the substrate layer 40 is preferably 1.40 to 1.70, and more preferably 1.43 to 1.65.

[0149] [Adhesive Layer] The thicknesses of the first adhesive layer 20, the second adhesive layer 30, and the adhesive layer 76 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 first adhesive layer 20, the second adhesive layer 30, and the adhesive layer 76 are each independently preferably from 1.42 to 1.60, more preferably from 1.47 to 1.58. The refractive indexes of the first adhesive layer 20, the second adhesive layer 30, and the adhesive layer 76 are preferably close to the refractive index of the light-guiding layer 50, the base layer 40, or the shaped film 72 to which they are in contact, and the absolute value of the difference in refractive index is preferably 0.2 or less.

[0150] The optical member obtained by the manufacturing method according to the embodiment 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. Furthermore, the optical member obtained by the manufacturing method according to the embodiment of the present invention is suitable for use as a component of the frontlight of a reflective display, which is an example of signage. Using the optical member obtained by the manufacturing method according to the embodiment 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.

[0151] REFERENCE SIGNS LIST 1 Optical member 10 First layer 12 First region 14 Second region 20 Second layer (first adhesive layer) 30 Third layer (second adhesive layer) 40 Base layer 50 Light guide layer 70 Direction conversion layer 72 Shape-imparting film 74 Recess 76 Adhesive layer 100 Optical element IS Internal space

Claims

1. Step A of providing a porous layer supported on a substrate; a step B of removing a partial region of the porous layer by irradiating the porous layer with laser light, the partial region to be removed including a plurality of discrete island regions; After the step B, a step C of disposing a first adhesive layer on the porous layer; A method for producing an optical member, comprising the steps of:

2. After the step C, a step D of peeling the substrate from the porous layer; After the step D, a step E of disposing a second adhesive layer on the porous layer opposite to the first adhesive layer; The method for producing an optical member according to claim 1 , further comprising:

3. The absorption coefficient of the substrate for the laser light is 500 cm －１ The method for producing an optical member according to claim 1 or 2, wherein the method is as described above.

4. The method for manufacturing an optical member according to claim 1 , wherein the light intensity distribution of the laser light is a top hat type.

5. The method for manufacturing an optical member according to claim 1 , wherein the laser light is an ultraviolet laser light.

6. The absorption coefficient of the substrate for the ultraviolet laser light is 1000 cm －１ The method for producing an optical member according to claim 5 .

7. 3. The method for producing an optical member according to claim 1, wherein in step A, the porous layer is formed on a release layer provided on the substrate.

8. The method for producing an optical member according to claim 7 , wherein the release layer is mainly composed of a polymer that does not contain a polar group.

9. The method for producing an optical member according to claim 7 , wherein the release layer is formed from a cycloolefin polymer.

10. The method for producing an optical member according to claim 9 , wherein the release layer has a thickness of 500 nm or less.