Multilayer sheet and method for manufacturing multilayer sheet

Abstract

Provided is a multilayer sheet which exhibits light diffusivity ultimately, has high visibility in a production process, and is easy to align. A multilayer sheet in which a sheet is releasably laminated on at least one main surface of a curable resin layer, the surface roughness of the sheet in contact with the curable resin layer being greater than the surface roughness of the sheet on the non-contact surface side, and the linear transmittance ratio represented by the following formula being 2 or more. (The linear transmittance at 800 nm of the multilayer sheet before peeling / the linear transmittance at 800 nm of the multilayer sheet obtained by peeling the sheet having a surface having a large surface roughness).

Description

Technical Field

[0001] The present invention relates to a multilayer sheet and a method for manufacturing the multilayer sheet. Background Art

[0002] Conventionally, in order to improve luminous efficiency and / or light reception efficiency, a light diffusion layer is formed in a light-emitting element and / or a light-receiving element included in an optoelectronic component such as an optical distance measurement sensor that optically measures the distance to an object. Summary of the Invention

[0003] Problems to be Solved by the Invention

[0004] In the case of forming a light diffusion layer using a multilayer sheet such as a multilayer resin sheet, a multilayer sheet in which sheets are laminated on both sides of a curable resin layer containing a filler (filler) in a peelable manner has been conventionally used. Specifically, for example, as Figure 1 shown, a multilayer sheet 100 obtained by laminating a flat substrate 15 having a flat surface, a curable resin layer 16 containing a filler, and a release liner 17 in this order is used.

[0005] When the multilayer sheet 100 is attached to the substrate 18, first, the release liner 17 is peeled off, and the curable resin layer 16 exposed on the surface is pressed against the substrate 18, whereby the multilayer sheet 100 is attached to the substrate 18. Next, the flat substrate 15 is peeled off from the curable resin layer 16, whereby the curable resin layer 16 is provided on the substrate 18. Moreover, since the curable resin layer 16 contains a filler, it functions as a light diffusion layer.

[0006] The present inventors conducted in-depth research and found that: in this conventional method, since the curable resin layer 16 contains a filler, the light transmittance is low, and when the multilayer sheet 100 is attached to the substrate 18, the visual recognition is poor, and it is difficult to attach the multilayer sheet 100 (alignment) to an accurate position on the substrate 18.

[0007] Here, in order to enable alignment, the curable resin layer 16 containing a filler was changed to a curable resin layer 26 not containing a filler. In this case, specifically, for example, as Figure 2 shown, a multilayer sheet 200 obtained by laminating a flat substrate 15 having a flat surface, a curable resin layer 26 not containing a filler, and a release liner 17 in this order is used.

[0008] When laminating the multi-layer sheet 200 onto the substrate 18, first, the release liner 17 is peeled off, and the curable resin layer 26 exposed on the surface is pressed against the substrate 18, thereby laminating the multi-layer sheet 200 onto the substrate 18. At this time, since the curable resin layer 26 does not contain a filler, it has high light transmittance, and when laminating the multi-layer sheet 200 onto the substrate 18, the visual recognition is good, and the multi-layer sheet 200 can be laminated at an accurate position on the substrate 18 (alignment). Then, the flat substrate 15 is peeled off from the curable resin layer 26, thereby disposing the curable resin layer 26 on the substrate 18. However, since the curable resin layer 26 does not contain a filler, it cannot function as a light diffusion layer. Figure 3 is a photograph showing an example of the surface of the conventional curable resin layer 26. As Figure 3 shown, the surface of the curable resin layer 26 is flat. Since the curable resin layer 26 does not contain a filler and the surface is flat like this, it cannot function as a light diffusion layer.

[0009] In the method studied by the present inventor, it was clarified that the curable resin layer 26 does not contain a filler, so although alignment can be performed, it does not function as a light diffusion layer.

[0010] As described above, the present inventor conducted in-depth research, and as a result, it was newly clarified that: in the prior art, there is room for improvement in providing a multi-layer sheet that finally exhibits light diffusibility and has high visual recognition and is easy to align in the production process.

[0011] The present invention was completed to solve the new problems found by the present inventor, and its object is to provide a multi-layer sheet that finally exhibits light diffusibility and has high visual recognition and is easy to align in the production process.

[0012] Means for Solving the Problem

[0013] The present invention (1) relates to a multi-layer sheet in which a sheet is laminated on at least one main surface of a curable resin layer in a peelable manner, wherein the surface roughness of the contact surface of the sheet with the curable resin layer is larger than the surface roughness on the non-contact surface side,

[0014] The linear transmittance ratio represented by the following formula is 2 or more,

[0015] (Linear transmittance at 800 nm of the multi-layer sheet before peeling / Linear transmittance at 800 nm of the multi-layer sheet with the sheet having a large surface roughness peeled off).

[0016] The present invention (2) relates to the multi-layer sheet according to the present invention (1), wherein the linear transmittance at 800 nm of the multi-layer sheet before peeling is 60% or more.

[0017] The present invention (3) relates to the multilayer sheet according to the present invention (1) or (2), wherein the linear transmittance at 800 nm of the multilayer sheet from which the sheet having a surface with large surface roughness has been peeled off is 10% or less.

[0018] The present invention (4) relates to the multilayer sheet according to any one of the present inventions (1) to (3), wherein the surface area ratio parameter Sdr of the surface with large surface roughness of the sheet having a surface with large surface roughness is 0.10 or more, and the maximum height parameter Rz of the line roughness of the surface with large surface roughness of the sheet having a surface with large surface roughness is 8.0 μm or more.

[0019] The present invention (5) relates to the multilayer sheet according to any one of the present inventions (1) to (4), wherein the multilayer sheet is for optical use.

[0020] The present invention (6) relates to the multilayer sheet according to any one of the present inventions (1) to (5), wherein the multilayer sheet is used as a light diffusion layer.

[0021] In addition, the present invention (7) relates to an optical material, wherein the optical material is an optical material obtained by curing the multilayer sheet according to any one of the present inventions (1) to (6).

[0022] In addition, the present invention (8) relates to the optical material according to the present invention (7), wherein the optical material is a light diffusion layer.

[0023] In addition, the present invention (9) relates to a method for manufacturing the multilayer sheet according to any one of the present inventions (1) to (6), wherein the manufacturing method includes a step of forming a curable resin layer on the surface with large surface roughness of the sheet A having a surface with large surface roughness.

[0024] In addition, the present invention (10) relates to a method for manufacturing the multilayer sheet according to any one of the present inventions (1) to (6), wherein the manufacturing method includes a step of forming a curable resin layer on the surface with large surface roughness of the sheet A having a surface with large surface roughness; and a step of laminating the sheet B on the surface of the curable resin layer opposite to the sheet A having a surface with large surface roughness.

[0025] Advantages of the Invention

[0026] The multilayer sheet of the present invention is a multilayer sheet in which a sheet is laminated on at least one main surface of a curable resin layer in a peelable manner, the surface roughness of the contact surface of the sheet with the curable resin layer is larger than that of the non-contact surface side, and the linear transmittance ratio represented by the above formula is 2 or more. Therefore, finally, while exhibiting light diffusibility, the visual recognition property is high in the production process and alignment becomes easy. Description of the Drawings

[0027] Figure 1 A figure schematically showing an example of a case where a conventional multi-layer sheet is adhered to a substrate.

[0028] Figure 2 A figure schematically showing an example of a case where a conventional multi-layer sheet is adhered to a substrate.

[0029] Figure 3 A photograph showing an example of the surface of a conventional curable resin layer.

[0030] Figure 4 A figure schematically showing an example of a case where the multi-layer sheet of the present invention is adhered to a substrate.

[0031] Figure 5 A photograph showing an example of the surface of a light extinction-treated substrate.

[0032] Figure 6 A photograph showing an example of the surface of the curable resin layer of the present invention.

[0033] Figure 7 A cross-sectional view schematically showing an example of the multi-layer sheet of the present invention.

[0034] Figure 8 A cross-sectional view schematically showing an example of the multi-layer sheet of the present invention after peeling off the release liner.

[0035] Figure 9 A cross-sectional view schematically showing an example of the multi-layer sheet of the present invention after peeling off the release liner and the light extinction-treated substrate. Detailed Description

[0036] <Multi-layer Sheet>

[0037] The multi-layer sheet of the present invention (preferably a multi-layer resin sheet) is a multi-layer sheet in which a sheet (preferably a resin sheet) is laminated in a peelable manner on at least one main surface of a curable resin layer, and the surface roughness of the contact surface of the sheet with the curable resin layer is larger than the surface roughness on the non-contact surface side, and the linear transmittance ratio represented by the following formula is 2 or more. As a result, finally, while exhibiting light diffusibility, the visual recognition property is high in the production process and alignment becomes easy.

[0038] (Linear transmittance at 800 nm of the multi-layer sheet before peeling / Linear transmittance at 800 nm of the multi-layer sheet after peeling off the sheet having a surface with a large surface roughness)

[0039] The reason for obtaining the above effects by the above multi-layer sheet is presumed as follows.

[0040] The multi-layer sheet of the present invention is a multi-layer sheet in which a sheet is laminated on at least one main surface of a curable resin layer in a peelable manner, and the surface roughness of the contact surface of the peelably laminated sheet with the curable resin layer is greater than that of the non-contact surface side. Therefore, by peeling the sheet having a large surface roughness from the curable resin layer, the surface roughness of the surface of the curable resin layer that is the contact surface with the sheet having a large surface roughness becomes large, and the curable resin layer functions as a light diffusion layer.

[0041] Moreover, the linear transmittance shown in the above formula is 2 or more. Thus, before peeling the sheet, the multi-layer sheet has high light transmittance, and when the multi-layer sheet is adhered to a substrate, the visual recognition is good, and the multi-layer sheet can be adhered to the accurate position of the substrate (alignment). Also, the linear transmittance of the curable resin layer after peeling the sheet is low, and it can function as a light diffusion layer.

[0042] An example of the case of adhering the multi-layer sheet of the present invention to a substrate will be described with reference to the drawings. For example, as Figure 4 shown, a multi-layer sheet 1 obtained by laminating in sequence a matte-treated substrate 25 having a surface with a large surface roughness, a curable resin layer 26 not containing a filler, and a release liner 17 is used. Figure 5 This is a photograph showing an example of the surface of the matte-treated substrate (the surface that becomes the contact surface with the curable resin layer). As Figure 5 shown, the surface of the matte-treated substrate that becomes the contact surface with the curable resin layer has a large surface roughness.

[0043] When adhering the multi-layer sheet 1 to a substrate 18, first, the release liner 17 is peeled off, and the curable resin layer 26 exposed on the surface is pressed against the substrate 18, thereby adhering the multi-layer sheet 1 to the substrate 18. At this time, since the curable resin layer 26 does not contain a filler, the light transmittance is high, and when the multi-layer sheet 1 is adhered to the substrate 18, the visual recognition is good, and the multi-layer sheet 1 can be adhered to the accurate position of the substrate 18 (alignment). Then, the matte-treated substrate 25 is peeled off from the curable resin layer 26, thereby disposing the curable resin layer 26 on the substrate 18. Since the surface roughness of the surface of the curable resin layer 26 that is the contact surface with the matte-treated substrate 25 is large, it can function as a light diffusion layer. Figure 6 This is a photograph showing an example of the surface of the curable resin layer 26 of the present invention (the surface that is the contact surface with the matte-treated substrate). As Figure 6 shown, the surface of the curable resin layer 26 that is the contact surface with the matte-treated substrate has a large surface roughness, so it can function as a light diffusion layer.

[0044] Figure 7 This is a cross-sectional view schematically showing an example of the multi-layer sheet of the present invention.

[0045] The multilayer sheet 1 is obtained by sequentially laminating a matte-treated substrate 25 having a surface with a large surface roughness, a curable resin layer 26, and a release liner 17 on one side in the thickness direction. The matte-treated substrate 25, the curable resin layer 26, and the release liner 17 each have a shape extending in a direction (plane direction) orthogonal to the thickness direction. It can be seen that the multilayer sheet 1 has the matte-treated substrate 25 on one major surface of the curable resin layer 26 and the release liner 17 on the other major surface of the curable resin layer 26.

[0046] Figure 8 Fig. is a cross-sectional view schematically showing an example of the multilayer sheet of the present invention after the release liner is peeled off.

[0047] The multilayer sheet 2 is obtained by sequentially laminating a matte-treated substrate 25 having a surface with a large surface roughness and a curable resin layer 26 on one side in the thickness direction. It can be seen that the multilayer sheet 2 has the matte-treated substrate 25 on one major surface of the curable resin layer 26, and the other major surface of the curable resin layer 26 forms the surface of the multilayer sheet 2.

[0048] Figure 9 Fig. is a cross-sectional view schematically showing an example of the multilayer sheet of the present invention after the release liner and the matte-treated substrate are peeled off.

[0049] The sheet 3 is composed of a single layer of the curable resin layer 26. It can be seen that the multilayer sheet of the present invention after the release liner and the matte-treated substrate are peeled off is a sheet composed of a single layer of the curable resin layer 26. The curable resin layer 26 has two major surfaces, a flat surface 32 and a rough surface 33.

[0050] As Figure 7 , Figure 8 shown, in the multilayer sheet 1 and the multilayer sheet 2, the curable resin layer 26 is in contact with the matte-treated substrate 25 on the surface of the matte-treated substrate 25 having a large surface roughness. As Figure 7 shown, in the multilayer sheet 1, the matte-treated substrate 25 and the release liner 17 are respectively in contact with the curable resin layer 26, and the respective surfaces in contact with the curable resin layer 26 have been subjected to a release treatment so as to be peelable from the curable resin layer 26. As described above, the multilayer sheet 1 has sheets (the matte-treated substrate 25 and the release liner 17) peelably on both sides of the curable resin layer 26.

[0051] There is no particular limitation on the release treatment applied to the surfaces of the matte-treated substrate and the release liner. The release treatment can use, for example: silicone-based release agents, amino-based release agents, alkyd-based release agents, fluorine-containing release agents, long-chain alkyl-based release agents, fatty acid amide-based release agents, etc. These substances can be used alone or in combination of two or more.

[0052] In addition to the release treatment, various surface treatments such as anti-fouling treatment and antistatic treatment can also be performed on the surfaces of the matting-treated substrate and the release liner. Silica powder can be used for the anti-fouling treatment. For the antistatic treatment, coating-type antistatic treatment, kneading-type antistatic treatment, and vapor deposition-type antistatic treatment can be adopted. These treatments can be used alone or in combination of two or more.

[0053] The surface roughness of the contact surface 30 of the matting-treated substrate 25 with the curable resin layer 26 is larger than that of the non-contact surface 31 side. Thus, by peeling the matting-treated substrate 25 from the curable resin layer 26, the surface roughness of the contact surface 30 of the matting-treated substrate 25 is transferred to the surface of the curable resin layer 26, the surface roughness of the surface of the curable resin layer 26 can be increased, and the curable resin layer 26 can function as a light diffusion layer. In addition, in the state before the matting-treated substrate 25 is peeled from the curable resin layer 26, the surface roughness of the non-contact surface 31 of the matting-treated substrate 25 constituting the surface of the multilayer sheet 1 is smaller than that of the contact surface 30, light diffusion can be suppressed, so the light transmittance is high. When the multilayer sheet 1 is adhered to the substrate 18, the visual recognition is good, and the multilayer sheet 1 can be adhered to the accurate position of the substrate 18 (alignment).

[0054] <<Sheet having a surface with large surface roughness (matting-treated substrate)>>

[0055] The surface area ratio parameter Sdr of the surface with large surface roughness of the sheet having a surface with large surface roughness, that is, the matting-treated substrate ( Figure 7 in which is surface 30) is preferably 0.10 or more, more preferably 0.12 or more, further preferably 0.15 or more, particularly preferably 0.18 or more, and most preferably 0.22 or more. The larger Sdr is, the more preferable it is, so there is no particular limitation on the upper limit.

[0056] In this specification, the surface area ratio parameter Sdr is also referred to as the parameter of the developed area ratio of the interface, and is an index indicating how much the developed area (surface area) of the defined area increases relative to the area of the defined area. The smaller the value, the flatter the surface means. In this specification, the surface area ratio parameter Sdr is measured based on the "non-contact (optical probe)" evaluation method of ISO25178.

[0057] The surface area ratio parameter Sdr of the surface with large surface roughness of the sheet having a surface with large surface roughness, that is, the matting-treated substrate ( Figure 7 in which is surface 30) of the maximum height parameter Rz of the line roughness is preferably 8.0 μm or more, more preferably 8.1 μm or more, further preferably 8.5 μm or more, particularly preferably 9.0 μm or more. The larger Rz is, the more preferable it is, so there is no particular limitation on the upper limit, and it is preferably less than 50 μm.

[0058] In this specification, the maximum height parameter Rz of line roughness is a height-direction parameter of the maximum height roughness also known as line roughness. It is a part of the roughness curve measured by a roughness meter selected with a reference length and is calculated as the sum of the highest part (maximum peak height: Rp) and the deepest part (maximum valley depth: Rv). The smaller the value, the flatter the surface. In this specification, the maximum height parameter Rz of line roughness is measured in accordance with JIS B0601-2001.

[0059] The sheet having a surface with large surface roughness, i.e., the matte-treated substrate, is the sheet layer that is finally peeled off. Therefore, as long as the surface area ratio parameter Sdr of the surface with small surface roughness ( Figure 7 in this case, surface 31) is within the range that does not affect the production of the curable resin layer, there is no limitation. From the viewpoint of ensuring better visual recognition in the production process, the smaller the better, preferably less than 0.10, more preferably 0.08 or less, further preferably 0.06 or less, and particularly preferably 0 (flat).

[0060] The sheet having a surface with large surface roughness, i.e., the matte-treated substrate, is the sheet layer that is finally peeled off. Therefore, as long as the maximum height parameter Rz of the line roughness of the surface with small surface roughness ( Figure 7 in this case, surface 31) is within the range that does not affect the production of the curable resin layer, there is no limitation. From the viewpoint of ensuring better visual recognition in the production process, the smaller the better, preferably less than 8.0 μm, more preferably 7.5 μm or less, further preferably 6.0 μm or less, and particularly preferably 0 μm (flat).

[0061] In order to be able to laminate the multi-layer sheet to the accurate position (alignment) of the substrate, the matte-treated substrate preferably has light transmittance. Therefore, as the material of the matte-treated substrate, a transparent resin (resin film) is preferred. For example, it can be mentioned: (meth)acrylic resin, phenoxy resin, epoxy resin, polyester resin, polyolefin resin, polycarbonate resin, polyethersulfone resin, polyarylate resin, melamine resin, polyamide resin, polyimide resin, cellulose resin, polystyrene resin, etc. These substances can be used alone or in combination of two or more. Among them, from the viewpoints of transparency and strength, a polyester resin is preferred, and PET resin (polyethylene terephthalate resin) is more preferred.

[0062] The thickness of the matte-treated substrate is, for example, 1 μm to 100 μm.

[0063] Within the range where necessary visual recognition is ensured, various additives such as fillers (inorganic fillers, organic fillers, etc.), anti-aging agents, antioxidants, ultraviolet absorbers, lubricants, plasticizers, colorants (pigments, dyes, etc.) can be incorporated into the matte-treated substrate as needed. These substances can be used alone or in combination of two or more.

[0064] <<Curable resin layer>>

[0065] On the contact surface of the curable resin layer (curable sheet) with the matte-treated substrate ( Figure 8 , Figure 9 in which is surface 33), the surface roughness of the contact surface of the matte-treated substrate is transferred. Therefore, the surface area ratio parameter Sdr and the maximum height parameter Rz of the line roughness of the contact surface with the matte-treated substrate are the same as those of the surface of the matte-treated substrate with a larger surface roughness.

[0066] On the surface of the curable resin layer, the contact surface with the release liner ( Figure 8 , 9 in which is surface 32) preferably has a smaller surface area ratio parameter Sdr, preferably less than 0.10, more preferably 0.08 or less, further preferably 0.05 or less, and particularly preferably 0 (flat).

[0067] On the surface of the curable resin layer, the contact surface with the release liner ( Figure 8 , 9 in which is surface 32) preferably has a smaller maximum height parameter Rz of the line roughness, preferably less than 8.0 μm, more preferably 7.5 μm or less, and further preferably 6.0 μm or less.

[0068] The curable resin layer is a layer formed from a curable resin composition. In order to accurately position (align) the multi-layer sheet on the substrate, the curable resin layer preferably has light transmissivity. Therefore, the composition of the curable resin composition is not particularly limited as long as it has light transmissivity. The curable resin composition is a composition containing a curable resin. As the curable resin, for example, the transparent resins listed as the materials for the matte-treated substrate can be used. These substances can be used alone or in combination of two or more. Among them, in applications requiring heat resistance, etc., from the viewpoint of high reliability, (meth)acrylic resins, phenoxy resins, epoxy resins, glycidyl acrylate resins, silicone resins, etc. are preferred.

[0069] As the (meth)acrylic resin, for example, polymers obtained by polymerizing monomers such as (meth)acrylic acid alkyl esters, (meth)acrylic acid cycloalkyl esters, (meth)acrylic acid aryl esters, etc. are exemplified. It should be noted that in this specification, "(meth)acrylic acid" means "acrylic acid and / or methacrylic acid".

[0070] As the (meth)acrylic acid alkyl ester, for example, (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid propyl ester, (meth)acrylic acid isopropyl ester, (meth)acrylic acid butyl ester, (meth)acrylic acid isobutyl ester, (meth)acrylic acid sec-butyl ester, (meth)acrylic acid tert-butyl ester, (meth)acrylic acid pentyl ester, (meth)acrylic acid isopentyl ester, (meth)acrylic acid hexyl ester, (meth)acrylic acid heptyl ester, (meth)acrylic acid octyl ester, (meth)acrylic acid 2-ethylhexyl ester, (meth)acrylic acid isooctyl ester, (meth)acrylic acid nonyl ester, (meth)acrylic acid decyl ester, (meth)acrylic acidisodecyl ester, (meth)acrylic acid undecyl ester, (meth)acrylic acid dodecyl ester, (meth)acrylic acid tridecyl ester, (meth)acrylic acid tetradecyl ester, (meth)acrylic acid hexadecyl ester, (meth)acrylic acid octadecyl ester, (meth)acrylic acid eicosyl ester, etc. are exemplified. As the (meth)acrylic acid cycloalkyl ester, for example, (meth)acrylic acid cyclopentyl ester, (meth)acrylic acid cyclohexyl ester, etc. are exemplified. As the (meth)acrylic acid aryl ester, for example, (meth)acrylic acid phenyl ester, (meth)acrylic acid benzyl ester, etc. are exemplified. These (meth)acrylic acid esters can be used alone or in combination of two or more.

[0071] Other monomers copolymerizable with the above-mentioned (meth)acrylate can also be copolymerized in the (meth)acrylic resin. Examples of other monomers include: carboxyl group-containing monomers, acid anhydride monomers, hydroxyl group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, acrylamide, acrylonitrile, etc. Examples of carboxyl group-containing monomers include: (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, etc. Examples of acid anhydride monomers include: maleic anhydride, itaconic anhydride, etc. Examples of hydroxyl group-containing monomers include: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl (meth)acrylate, etc. Examples of sulfonic acid group-containing monomers include: styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, (meth)acryloxynaphthalenesulfonic acid, etc. Examples of phosphoric acid group-containing monomers include: 2-hydroxyethyl acryloyl phosphate, etc. These other monomers can be used alone or in combination of two or more.

[0072] The polymerization method of the (meth)acrylic resin is not particularly limited, and examples thereof include: solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization, etc.

[0073] Examples of the phenoxy resin include polyhydroxy polyethers formed by polymerization of bisphenols and epichlorohydrin. Examples of bisphenols include bisphenol A and bisphenol F, and bisphenol A is preferred from the viewpoints of transparency and heat resistance.

[0074] As the epoxy resin, an epoxy resin with less coloring is preferred, and examples thereof include: bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resins such as isocyanuric acid triglycidyl ester and hydantoin epoxy resin, hydrogenated bisphenol A type epoxy resin, aliphatic epoxy resin, glycidyl ether type epoxy resin, cresol novolac type epoxy resin, etc.

[0075] The content of the curable resin in 100% by mass of the curable resin layer is, for example, 35% by mass to 99.5% by mass.

[0076] The curable resin composition can be a photocurable resin composition or a thermosetting resin composition.

[0077] When the curable resin composition is a photocurable resin composition, it preferably contains a photoinitiator. As the photoinitiator, there is no particular limitation as long as it contains a group having the property of generating an ion pair or a radical by light absorption. For example, a photo cationic polymerization initiator having a photo cationic polymerization initiating group, a photo radical polymerization initiator having a photo radical generating group, etc. can be cited. These substances can be used alone or in combination of two or more.

[0078] The photo cationic polymerization initiator generates a cationic species or a Lewis acid by irradiating active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, thereby initiating a polymerization reaction. As the photo cationic polymerization initiator, a photoacid generator, a photobase generator, etc. are preferred, and a photoacid generator is more preferred.

[0079] The content of the photoinitiator in 100% by mass of the curable resin layer is, for example, 0.5% by mass to 10% by mass.

[0080] When the curable resin composition is a thermosetting resin composition, it preferably contains a curing agent and / or a curing accelerator.

[0081] Examples of the curing agent include acid anhydride curing agents such as chain polycarboxylic anhydrides, aromatic polycarboxylic anhydrides, and alicyclic acid anhydrides; phenolic curing agents; amine curing agents, etc. These substances can be used alone or in combination of two or more. Among them, phenolic curing agents are preferred.

[0082] The content of the curing agent in 100% by mass of the curable resin layer is, for example, 10% by mass to 50% by mass.

[0083] Examples of the curing accelerator include tertiary amines such as triethanolamine; imidazoles such as 2-methylimidazole, 2-ethyl-4-methylimidazole, and 2-methyl-4-methylimidazole; organic phosphorus compounds such as tributyl(methyl)phosphonium dimethyl phosphate, tetraphenylphosphonium·tetraphenylborate, and triphenylphosphine; diazabicycloolefin compounds such as 1,8-diazabicyclo[5.4.0]undec-7-ene and 1,5-diazabicyclo[4.3.0]non-5-ene, etc. These substances can be used alone or in combination of two or more.

[0084] The content of the curing accelerator in 100% by mass of the curable resin layer is, for example, 0.05% by mass to 1% by mass.

[0085] The thickness of the curable resin layer is, for example, 1 μm to 200 μm.

[0086] Within the range with necessary visual recognition, various additives such as fillers (inorganic fillers, organic fillers, etc.), anti-aging agents, antioxidants, ultraviolet absorbers, lubricants, plasticizers, colorants (pigments, dyes, etc.) can be incorporated into the curable resin layer as needed. These substances can be used alone or in combination of two or more.

[0087] The curable resin composition may contain a solvent as needed.

[0088] There is no particular limitation on the solvent. For example, esters such as ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, etc.; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.; polar solvents such as dimethylformamide, dimethyl sulfoxide, etc.; halogenated solvents such as 1,1,1-trichloroethane, chloroform, etc.; ethers such as tetrahydrofuran, dioxane, etc.; aromatic compounds such as benzene, toluene, xylene, etc.; fluorinated inert liquids such as perfluorooctane, perfluorotri-N-butylamine, etc. These substances can be used alone or in combination of two or more. Among them, from the viewpoint of compatibility with the solute, methyl ethyl ketone is preferred.

[0089] The curable resin layer is a layer formed from the curable resin composition. When the curable resin composition contains a solvent, it is formed by drying the solvent as needed. Here, when the curable resin composition contains a solvent, the curable resin layer is usually formed by drying the solvent. Moreover, the solvent is only appropriately used for the purpose of promoting the mixing of the components contained in the composition. Therefore, when the photocurable resin composition contains a solvent, the content of the solvent is not particularly limited.

[0090] <<Release Liner>>

[0091] In the surface of the release liner (sheet), the smaller the surface area ratio parameter Sdr of the contact surface with the curable resin layer ( Figure 7 which is surface 34 herein) is, the better. It is preferably less than 0.10, more preferably 0.08 or less, and further preferably 0 (flat).

[0092] In the surface of the release liner (sheet), the smaller the maximum height parameter Rz of the line roughness of the contact surface with the curable resin layer ( Figure 7 which is surface 34 herein) is, the better. It is preferably less than 8.0 μm, more preferably 7.5 μm or less, further preferably 7.0 μm or less, and particularly preferably 0 μm (flat).

[0093] In the surface of the release liner (sheet), the roughness of the surface on the side opposite to the contact surface with the curable resin layer ( Figure 7 which is surface 35 herein) has no influence when laminating the multi-layer sheet to the substrate, so there is no particular limitation. It is preferably the same as the contact surface with the curable resin layer ( Figure 7It is the same as the middle surface 34).

[0094] As the release liner, as long as it is a release liner applicable to the adhesive sheet, there is usually no particular limitation, and any appropriate release liner can be used. As such a release liner, for example, the following can be cited: a substrate having a release treatment layer, a low tack substrate containing a fluoropolymer, and a low tack substrate containing a non-polar polymer.

[0095] As the substrate having a release treatment layer, for example, a plastic film or paper subjected to a release treatment can be cited.

[0096] The material of the plastic film is not particularly limited. For example, the following can be cited: polyolefin, polyester, polyurethane, polycarbonate, polyether ether ketone, polyimide, polyetherimide, polyamide, wholly aromatic polyamide, polyvinyl chloride, polyvinylidene chloride, polyphenylene sulfide, aromatic polyamide, fluororesin, cellulose resin, silicone resin, etc. As the polyolefin, for example, the following can be cited: low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, ultra low density polyethylene, random copolymerized polypropylene, block copolymerized polypropylene, homopolypropylene, polybutene, polymethylpentene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylate copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, etc. As the polyester, for example, the following can be cited: polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, etc. These materials can be used alone or in combination of two or more. In addition, the substrate can be a single-layer structure or a multi-layer structure. Furthermore, the substrate preferably has light transmittance. Therefore, a transparent resin is preferred.

[0097] As the fluoropolymer, for example, the following can be cited: polytetrafluoroethylene, poly(chlorotrifluoroethylene), poly(vinyl fluoride), poly(vinylidene fluoride), tetrafluoroethylene-hexafluoropropylene copolymer, chlorofluoroethylene-vinylidene fluoride copolymer. These substances can be used alone or in combination of two or more.

[0098] As the non-polar polymer, for example, the following can be cited: olefin resins such as polyethylene and polypropylene. These substances can be used alone or in combination of two or more.

[0099] The thickness of the release liner is, for example, 1 μm to 100 μm.

[0100] Various additives such as fillers (inorganic fillers, organic fillers, etc.), anti-aging agents, antioxidants, ultraviolet absorbers, lubricants, plasticizers, colorants (pigments, dyes, etc.) can be incorporated into the release liner as needed. These substances can be used alone or in combination of two or more.

[0101] <<Properties of the multi-layer sheet>>

[0102] The linear transmittance ratio of the multi-layer sheet of the present invention, represented by the following formula, is 2 or more, preferably 4 or more, more preferably 7 or more, still more preferably 10 or more, and particularly preferably 11 or more. The larger the linear transmittance ratio, the more preferable it is, and thus there is no particular limitation on the upper limit.

[0103] (Linear transmittance at 800 nm of the multi-layer sheet before peeling / Linear transmittance at 800 nm of the multi-layer sheet after peeling off the sheet having a surface with large roughness)

[0104] Here, in the present specification, the multi-layer sheet before peeling in the description of the transmittance of the multi-layer sheet refers to the multi-layer sheet before peeling off the sheet having a surface with large roughness. In the presence of another sheet (peeling liner), the other sheet may or may not be peeled off.

[0105] In addition, in the present specification, the multi-layer sheet after peeling off the sheet having a surface with large roughness in the description of the transmittance of the multi-layer sheet refers to the multi-layer sheet after peeling off the sheet having a surface with large roughness. In the presence of another sheet (peeling liner), the other sheet may or may not be peeled off.

[0106] In the multi-layer sheet of the present invention, the linear transmittance at a wavelength of 800 nm of the multi-layer sheet before peeling is preferably 60% or more, more preferably 62% or more, and still more preferably 65% or more. The larger the linear transmittance, the more preferable it is, and thus there is no particular limitation on the upper limit.

[0107] In the multi-layer sheet of the present invention, the total light transmittance at a wavelength of 800 nm of the multi-layer sheet before peeling is preferably 70% or more, more preferably 72% or more, and still more preferably 75% or more. The larger the total light transmittance, the more preferable it is, and thus there is no particular limitation on the upper limit.

[0108] In the multi-layer sheet of the present invention, the linear transmittance at a wavelength of 800 nm of the multi-layer sheet after peeling off the sheet having a surface with large roughness is preferably 10% or less, more preferably 9% or less, and still more preferably 7% or less. The smaller the linear transmittance, the more preferable it is, and thus there is no particular limitation on the lower limit.

[0109] In the multi-layer sheet of the present invention, the total light transmittance at a wavelength of 800 nm of the multi-layer sheet after peeling off the sheet having a surface with large roughness is preferably 70% or more, more preferably 72% or more, and still more preferably 75% or more. The larger the total light transmittance, the more preferable it is, and thus there is no particular limitation on the upper limit.

[0110] In this specification, the linear transmittance and the total light transmittance are the transmittances at a wavelength of 800 nm at 25°C, and can be measured using a spectrophotometer. In addition, the measurement of the transmission spectrum is performed in the thickness direction of the sheet.

[0111] By suppressing the light absorption in the wavelength region of 800 nm of the raw materials for the light extinction-treated substrate, the curable resin layer, and the release liner, the linear transmittance and the total light transmittance at a wavelength of 800 nm can be adjusted to the above numerical ranges. In addition, by controlling the surface shape (roughness) of the light extinction-treated substrate, the curable resin layer, and the release liner, the linear transmittance at a wavelength of 800 nm can be controlled.

[0112] <<Manufacturing Method of Multilayer Sheet>>

[0113] The multilayer sheet is manufactured as follows, for example.

[0114] (1) Preparation of Light Extinction-Treated Substrate

[0115] Prepare a light extinction-treated substrate in which the surface area ratio parameter Sdr and the maximum height parameter Rz of the line roughness are adjusted to the above preferred numerical ranges. The light extinction-treated substrate can be a commercially available product or can be appropriately manufactured.

[0116] In the case of manufacturing the light extinction-treated substrate, the surface of the transparent resin film can be appropriately subjected to, for example, sandblasting, hairline processing, light extinction processing, embossing processing, regular uneven shape processing, irregular uneven shape processing, etc., so as to be adjusted to the desired surface roughness. In addition, a plurality of fine particles can be randomly (irregularly) dispersed and arranged on the surface of the transparent resin film by a known method, and another substrate can be pressed from above and the fine particles can be recovered to form an uneven surface, so as to be adjusted to the desired surface roughness. These processes can be performed alone or in combination of two or more.

[0117] (2) Formation of Curable Resin Layer

[0118] Next, a step of forming a curable resin layer on the surface of the light extinction-treated substrate (sheet A having a surface with a large surface roughness) having a large surface roughness is performed.

[0119] The curable resin layer can be formed by coating a curable resin composition on the surface of the light extinction-treated substrate having a large surface roughness to form a coating film, and then, when the curable resin composition contains a solvent, drying the solvent as needed. Thus, a multilayer sheet having a curable resin layer on the surface of the light extinction-treated substrate having a large surface roughness is obtained.

[0120] (3) Attachment of Release Liner

[0121] Next, the following steps are carried out: A multilayer sheet having a curable resin layer on the surface with a large surface roughness of the matte-treated substrate is used, and a sheet B (release liner) is adhered to the surface of the curable resin layer on the side opposite to the matte-treated substrate (sheet A having a surface with a large surface roughness).

[0122] By pressing the release liner onto the surface of the curable resin layer of the multilayer sheet having a curable resin layer on the surface with a large surface roughness of the matte-treated substrate, the release liner is adhered to the surface of the curable resin layer on the side opposite to the matte-treated substrate. Thus, a multilayer sheet in which a matte-treated substrate having a surface with a large surface roughness, a curable resin layer, and a release liner are laminated in this order toward one side in the thickness direction is obtained (refer to Figure 7 ).

[0123] Next, the curing of the curable resin composition will be described. When the curable resin composition is a photocurable resin composition, the curable resin layer is cured by light irradiation such as ultraviolet light. On the other hand, when the curable resin composition is a thermosetting resin composition, the curable resin layer is cured by heating.

[0124] In the form of a multilayer sheet in which a matte-treated substrate having a surface with a large surface roughness, a curable resin layer, and a release liner are laminated in this order toward one side in the thickness direction (for example, Figure 7 the multilayer sheet 1 shown), for the reason of being adhered to a substrate or the like in a subsequent process, the curable resin layer is preferably uncured. If the curable resin layer is cured first, it may not be able to adhere sufficiently when pasted onto a substrate or the like.

[0125] When adhering the multilayer sheet to a substrate, as described above, first, the release liner is peeled off, and the exposed curable resin layer on the surface is pressed against the substrate, thereby adhering the multilayer sheet to the substrate. At this time, when the curable resin layer has no adhesiveness, it is difficult to adhere the multilayer sheet to the substrate. At this time, heating or the like can be carried out as needed.

[0126] The adhesiveness of the curable resin composition is significantly reduced after curing, so it is preferably cured after adhering the multilayer sheet to the substrate. Thereby, the multilayer sheet can be adhered to the substrate more appropriately.

[0127] When the curable resin composition is a photocurable resin composition, it can be cured by light irradiation such as ultraviolet light irradiation (for example, near a wavelength of 365 nm). As the light source for light irradiation, LED, low-pressure mercury lamp, high-pressure mercury lamp, ultra-high-pressure mercury lamp, xenon lamp, etc. can be used. The irradiation amount is not particularly limited, and for example, 100 mJ / cm 2 ~10000 mJ / cm 2In addition, particularly in the case of a photo cationic curing system, a heat curing process can be carried out as needed. As the heating conditions, for example, conditions of carrying out for 5 minutes to 60 minutes at 80°C to 150°C can be cited.

[0128] In the case where the curable resin composition is a thermosetting resin composition, it can be cured by a heat curing process. As the heating conditions, for example, conditions of carrying out for 5 minutes to 60 minutes at 120°C to 180°C can be cited. In addition, for the purpose of promoting curing, sometimes additional post-heating is carried out afterwards.

[0129] In the above description, the case where the multilayer sheet of the present invention is obtained by laminating in the thickness direction in sequence an extinction treatment substrate having a surface with large surface roughness, a curable resin layer, and a release liner, and the sheet includes an extinction treatment substrate, a curable resin layer, and a release liner has been described. However, in the present invention, as long as it is a multilayer sheet in which a sheet having a surface with large surface roughness is peelably laminated on at least one main surface of the curable resin layer, the multilayer sheet of the present invention can be a sheet composed of an extinction treatment substrate and a curable resin layer obtained by laminating in the thickness direction in sequence an extinction treatment substrate having a surface with large surface roughness and a curable resin layer.

[0130] In addition, within the range not impairing the effects of the present invention, the multilayer sheet of the present invention may also have other layers other than the above. For example, the multilayer sheet of the present invention can be obtained by laminating in the thickness direction in sequence an extinction treatment substrate having a surface with large surface roughness, a curable resin layer, a release liner, and a protective layer for protecting the release liner.

[0131] The multilayer sheet of the present invention can also be made into a roll shape by winding the multilayer sheet of the present invention around a winding body. In addition, sheets cut into a specified size can be overlapped to make a single sheet.

[0132] The thickness of the multilayer sheet of the present invention is, for example, 80 μm to 350 μm.

[0133] The shape of the multilayer sheet of the present invention is not particularly limited, and for example, it is a polygon including a square and a rectangle, a circle, an ellipse, and a strip. The multilayer sheets in the shape of a polygon, a circle, and an ellipse can be circulated in a single-sheet form, and the multilayer sheets in a strip shape can be circulated in the form of a winding body (roll) wound around a core. The width of the multilayer sheet in a strip shape and the width of the winding body obtained by winding the multilayer sheet in a strip shape can be freely set.

[0134] <<Use of Multilayer Sheet>>

[0135] The multilayer sheet of the present invention (preferably the curable resin layer included in the multilayer sheet of the present invention) is used for optical applications (optoelectronic component applications) such as touch panels, displays, optoelectronics, lenses, optical sensors, and lighting devices. As described above, the multilayer sheet of the present invention (preferably the curable resin layer included in the multilayer sheet of the present invention) can function as a light diffusion layer, and thus is preferably used as a light diffusion layer. More specifically, the multilayer sheet of the present invention (preferably the curable resin layer included in the multilayer sheet of the present invention) is preferably used as a light diffusion layer for a light emitting element and / or a light receiving element included in optoelectronic components such as an optical distance measuring sensor that optically measures the distance to an object, and more preferably used as a light diffusion layer for a light emitting element and / or a light receiving element included in an optical distance measuring sensor.

[0136] In addition, the optical material of the present invention is characterized by being obtained by curing the multilayer sheet of the present invention (preferably the curable resin layer included in the multilayer sheet of the present invention). The optical material is not particularly limited, and examples thereof include optoelectronic components exemplified as optical applications.

[0137] As described above, the multilayer sheet of the present invention (preferably the curable resin layer included in the multilayer sheet of the present invention) can function as a light diffusion layer, and thus the optical material of the present invention is preferably a light diffusion layer. More specifically, the optical material of the present invention is preferably a light diffusion layer for a light emitting element and / or a light receiving element included in optoelectronic components such as an optical distance measuring sensor that optically measures the distance to an object, and more preferably used as a light diffusion layer for a light emitting element and / or a light receiving element included in an optical distance measuring sensor.

[0138] Examples

[0139] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Hereinafter, unless otherwise specified, "parts" or "%" refer to "parts by mass" or "% by mass", respectively.

[0140] The materials used in the examples and comparative examples are shown below.

[0141] (Curable resin composition)

[0142] Acrylic resin 1: glycidyl group-containing (meth)acrylic resin (MEK solution with a molecular weight of about 60,000 and a solid content of 40%)

[0143] Acrylic resin 2: SG-70L (manufactured by Nagase ChemteX Corporation) (MEK / toluene solution with a solid content of about 13%)

[0144] Phenoxy resin: YP70 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.)

[0145] Epoxy resin 1: YL980 (manufactured by Mitsubishi Chemical Corporation)

[0146] Epoxy resin 2: JER1010 (manufactured by Mitsubishi Chemical Corporation)

[0147] Epoxy resin 3: KI-3000 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.)

[0148] Phenolic resin: MEH-7851S (manufactured by Meiwafosis Co., Ltd.)

[0149] Photoacid generator: SP-170 (manufactured by ADEKA Corporation)

[0150] Thermal curing catalyst: TPP-K (manufactured by Kitakyo Chemical Industry Co., Ltd.)

[0151] Silica filler: SO-25R (manufactured by Admatechs Co., Ltd., average particle size 0.5 μm)

[0152] (Matte-treated substrate)

[0153] Matte-treated substrates A to F: Matte-treated substrates (resin sheets, resin: PET, filler content: 0 mass%) having the surface roughness (surface area ratio parameter Sdr of the surface with large surface roughness, maximum height parameter Rz of line roughness) described in Table 2

[0154] The surface area ratio parameter Sdr and the maximum height parameter Rz of line roughness of the surface with large surface roughness of the matte-treated substrate are measured by the following method using a laser microscope (VK-X, a laser microscope manufactured by Keyence Corporation).

[0155] (1) Sdr

[0156] Measurement is carried out according to the "non-contact (optical probe)" evaluation method of ISO25178. Specifically, the surface roughness of the surface with large surface roughness of the matte-treated substrate is calculated as the increase rate (%) of the surface area when the flat surface is set to 100%, and thus Sdr is calculated. The measurement of Sdr is carried out 5 times (i.e., N = 5), and the average value of them is adopted.

[0157] (2) Rz

[0158] For the surface with large surface roughness of the matte-treated substrate, the surface shape is measured at 25 °C and 50% RH according to JISB0601-2001. For the data (roughness curve) obtained by the above measurement, the maximum height (Rz) is obtained as the sum of the height Rp of the highest peak on the upper side from the average line of the roughness curve and the depth Rv of the deepest valley on the lower side from the above average line. The measurement conditions are as follows. The measurement of Rz is carried out 5 times (i.e., N = 5), and the average value of them is adopted.

[0159] (Release Liner)

[0160] Release Liner: A transparent resin sheet (resin: polyethylene terephthalate, filler content: 0 mass%)

[0161] In order to be able to peel from the curable resin layer, release treatment was performed on each surface of the matte-treated substrate and the release liner that came into contact with the curable resin layer, respectively.

[0162] Examples 1 to 6 and Comparative Examples 1 to 4

[0163] According to the formulation (mass ratio) shown in Table 1, methyl ethyl ketone was appropriately blended to facilitate the coating of the sheet, and the mixture was stirred at 2200 rpm for 5 minutes using a disperser and defoamed for 1.5 minutes using a planetary mixer, thereby preparing a curable resin composition.

[0164] The prepared curable resin composition was coated on the matte-treated substrate film (thickness: 50 μm) described in Table 2, and then the solvent was dried under the conditions of 130 °C for 2 minutes to form a curable resin layer, thereby obtaining a sheet with a thickness of 30 μm. In addition, a release liner with a thickness of 50 μm was pasted on the curable resin layer of the obtained sheet, thereby fabricating a three-layer sheet of matte-treated substrate film / curable resin layer / release liner.

[0165] Next, the matte-treated substrate film was peeled from the obtained three-layer sheet, thereby fabricating a two-layer sheet of curable resin layer / release liner.

[0166] The obtained sheets were evaluated by the following method. The evaluation results are shown in Table 2.

[0167] <Light transmittance>

[0168] For the obtained three-layer and two-layer sheets, the linear transmittance and total light transmittance were measured by the following method.

[0169] <<Linear transmittance>>

[0170] First, a quartz cell was filled with liquid paraffin manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., and the baseline was measured using a spectrophotometer V-670 manufactured by JASCO Corporation. Then, each sheet was sandwiched in a film measurement unit, and the light transmittance (linear transmittance) at a wavelength of 800 nm was measured at room temperature (25 °C) using a spectrophotometer (V-670 manufactured by JASCO Corporation). It should be noted that the measurement of the transmission spectrum was performed in the thickness direction of the sheet. In addition, the unit of the measurement results in the table is %.

[0171] <<Total light transmittance>>

[0172] Measurement was carried out using a spectrophotometer V-670 manufactured by JASCO Corporation equipped with accessories for integrating sphere measurement. First, the baseline was measured in the state without a sample. Then, each sheet was set in the sample measurement section, and the total transmittance at a wavelength of 800 nm was measured at room temperature (25 °C) using a spectrophotometer (V-670 manufactured by JASCO Corporation). It should be noted that the measurement of the transmission spectrum was carried out in the thickness direction of the sheet. In addition, the unit of the measurement results in the table is %.

[0173] <Visual recognition property>

[0174] Prepare a sheet of paper with the number 2 written in a circle with a diameter of 5 mm, arrange the obtained three-layer sheet at intervals of 1 cm, and evaluate the case where the number can be recognized from above as 〇 and the case where it cannot be recognized as ×.

[0175] In addition, for the obtained two-layer sheet, in the same way, the case where the number can be recognized was evaluated as 〇, and the case where it cannot be recognized was evaluated as ×.

[0176]

[0177]

[0178] As can be seen from Table 2, the multilayer sheet of the example is a multilayer sheet in which a sheet is laminated on at least one main surface of a curable resin layer in a peelable manner, and the surface roughness of the surface of the sheet in contact with the curable resin layer is larger than that on the non-contact surface side, and the linear transmittance ratio represented by the above formula is 2 or more. The multilayer sheet of this example finally exhibits light diffusibility while having high visual recognition property and being easy to align in the production process.

[0179] Industrial applicability

[0180] The present invention relates to a multilayer sheet which can be used for optical applications.

[0181] Reference numeral description

[0182] 1 Multilayer sheet

[0183] 2 Multilayer sheet after peeling the release liner

[0184] 3 Multilayer sheet after peeling the release liner and the light extinction treatment substrate

[0185] 15 Flat substrate

[0186] 16 Curable resin layer containing a filler

[0187] 17 Release liner

[0188] 18 Substrate

[0189] 25 Light extinction treatment substrate

[0190] 26 Curing resin layer without filler

[0191] 30 Contact surface of the matting-treated substrate with the curing resin layer

[0192] 31 Non-contact surface of the matting-treated substrate with the curing resin layer

[0193] 32 Surface of the curing resin layer

[0194] 33 Rough surface of the curing resin layer

[0195] 34 Contact surface of the release liner with the curing resin layer

[0196] 35 Non-contact surface of the release liner with the curing resin layer

[0197] 100 Conventional multi-layer sheet

[0198] 200 Conventional multi-layer sheet

Claims

1. A multilayer sheet, which is a multilayer sheet having a sheet laminated on at least one main surface of a curable resin layer in a peelable manner, wherein, the surface roughness of the contact surface of the sheet with the curable resin layer is greater than that of the non-contact surface side, the linear transmittance ratio represented by the following formula is 2 or more, (Linear transmittance at 800 nm of the multilayer sheet before peeling / Linear transmittance at 800 nm of the multilayer sheet after peeling off the sheet having the surface with greater roughness).

2. The multilayer sheet according to claim 1, wherein, The linear transmittance at 800 nm of the multilayer sheet before peeling is 60% or more.

3. The multilayer sheet according to claim 1, wherein, The linear transmittance at 800 nm of the multilayer sheet after peeling off the sheet having the surface with greater roughness is 10% or less.

4. The multilayer sheet according to claim 1, wherein, The surface area ratio parameter Sdr of the surface with greater roughness of the sheet having the surface with greater roughness is 0.10 or more, and the maximum height parameter Rz of the line roughness of the surface with greater roughness of the sheet having the surface with greater roughness is 8.0 μm or more.

5. The multilayer sheet according to claim 1, wherein, The multilayer sheet is for optical use.

6. The multi-layer sheet according to claim 1, wherein, The multilayer sheet is used as a light diffusion layer.

7. An optical material, wherein, The optical material is an optical material obtained by curing the multilayer sheet according to any one of claims 1 to 6.

8. The optical material according to claim 7, wherein, The optical material is a light diffusion layer.

9. A method for manufacturing a multilayer sheet according to any one of claims 1 to 6, wherein, The manufacturing method includes: a step of forming a curable resin layer on the surface with greater roughness of sheet A having a surface with greater roughness.

10. A method for manufacturing a multilayer sheet according to any one of claims 1 to 6, wherein, The manufacturing method includes: a step of forming a curable resin layer on the surface with greater roughness of sheet A having a surface with greater roughness; and a step of laminating sheet B on the surface of the curable resin layer opposite to sheet A having a surface with greater roughness.

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