Light-transmitting sheet and light display member

Abstract

A light-transmitting sheet according to the present invention comprises: a light-transmitting flexible layer (10); and a light-blocking wall (20) that is inside the flexible layer (10), the light-blocking wall (20) extending in the thickness direction of the flexible layer (10) and blocking light transmitted through the flexible layer (10). A light display member according to the present invention comprises a light-transmitting sheet according to the present invention and a light source. The present invention makes it possible to provide a light-transmitting sheet with which it is possible to prevent a hidden display region from performing display due to leakage of light from a light source, and a light display member comprising the aforementioned light-transmitting sheet.

Description

Light-transmitting sheet and optical display member

[0001] The present invention relates to a light-transmitting sheet having a flexible layer and an optical display member having the light-transmitting sheet.

[0002] In recent years, development of optical display members that use light to display information such as temperature, time, and vehicle speed inside vehicles such as automobiles has been actively promoted from the viewpoint of improving their performance. Optical display members must have excellent light transmittance in order to properly display information, and because they constitute part of the interior of the vehicle, they are required to have a luxurious feel, such as maintaining a soft feel and having excellent design.

[0003] As a laminate sheet used as a display member, for example, the laminate sheet described in Patent Document 1 is known as a prior art. The laminate sheet described in Patent Document 1 includes a base layer and a light-shielding layer, and thereby has a transmissive region that transmits visible light and a light-shielding region that blocks visible light in the thickness direction. As a result, by transmitting light from a light source through the laminate sheet, it is possible to display information such as temperature, time, vehicle speed, and images of various adjustment and setting buttons on the laminate sheet.

[0004] Japanese Patent Application Laid-Open No. 2023-3868

[0005] However, in the laminated sheet described in Patent Document 1, when multiple display areas are arranged side by side, when attempting to display only one display area, there are cases where light leakage from the light source causes display areas adjacent to that display area to also be displayed. Therefore, an object of the present invention is to provide a light-transmitting sheet that can prevent display areas that are not to be displayed from being displayed due to light leakage from the light source, and an optical display member including the light-transmitting sheet.

[0006] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by providing a light-shielding wall in a light-transmitting sheet, and have thus completed the present invention. The present invention is summarized as follows: [1] A light-transmitting sheet comprising: a flexible layer having light transparency; and a light-shielding wall disposed within the flexible layer, extending in the thickness direction of the flexible layer, and blocking light transmitted through the flexible layer. [2] The light-transmitting sheet according to [1] above, further comprising a light-shielding layer that blocks light transmitted through the flexible layer. [3] The light-transmitting sheet according to [1] or [2] above, wherein the material constituting the light-shielding wall has an Asker C hardness of 70 or less, a JIS-A hardness of 45 or less, or a penetration of 10 or more. [4] The light-transmitting sheet according to any one of [1] to [3] above, wherein the flexible layer is a foam layer having an Asker C hardness of 70 or less. [5] The light-transmitting sheet according to any one of [1] to [3] above, wherein the flexible layer is a rubber layer having a JIS-A hardness of 45 or less. [6] The light-transmitting sheet according to any one of [1] to [3] above, wherein the flexible layer is a gel layer having a penetration of 10 or more and 150 or less. [7] The light-transmitting sheet according to any one of [1] to [6] above, wherein the length of the light-shielding wall in the thickness direction of the flexible layer is 50% or more of the thickness of the flexible layer. [8] The light-transmitting sheet according to any one of [1] to [7] above, further comprising a light-transmitting surface layer. [9] An optical display member comprising the light-transmitting sheet according to any one of [1] to [8] above and a light source.

[0007] According to the present invention, it is possible to provide a light-transmitting sheet that can prevent an undisplayed display area from being displayed due to light leakage from a light source, and an optical display component equipped with the light-transmitting sheet.

[0008] FIG. 1 is a cross-sectional view of a light-transmitting sheet according to one embodiment of the present invention. FIG. 2 is a diagram illustrating a method for forming a light-shielding wall in a light-transmitting sheet according to one embodiment of the present invention. FIG. 3 is a cross-sectional view of a light-transmitting sheet according to another embodiment of the present invention. FIG. 4 is a cross-sectional view of a light-transmitting sheet according to another embodiment of the present invention. FIG. 5 is a cross-sectional view of a light-transmitting sheet according to another embodiment of the present invention. FIG. 6 is a cross-sectional view of a modified light-transmitting sheet according to one embodiment of the present invention. FIG. 7 is a diagram illustrating a method for forming a light-shielding wall in a modified light-transmitting sheet according to one embodiment of the present invention. FIG. 8 is a cross-sectional view of a light display member according to one embodiment of the present invention. FIG. 9 is a cross-sectional view of a light display member according to another embodiment of the present invention. FIG. 10 is a diagram illustrating a method for evaluating light leakage from a light-shielding wall.

[0009] [Light-Transmitting Sheet] A light-transmitting sheet according to one embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a light-transmitting sheet 1 according to one embodiment of the present invention comprises a light-transmitting flexible layer 10 and a light-shielding wall 20 located inside the flexible layer 10, extending in the thickness direction of the flexible layer 10, and blocking light passing through the flexible layer. This prevents a display area that is not to be displayed from being displayed due to light leakage from the light source. Note that "located inside the flexible layer 10" here includes not only a case where the entire light-shielding wall is located inside the flexible layer and not present on the surface of the flexible layer, but also a case where the light-shielding wall is located inside the flexible layer and a portion of the light-shielding wall is present on the surface of the flexible layer, as shown in FIG. 1.

[0010] (Flexible Layer) The flexible layer 10 is not particularly limited as long as it is a light-transmitting and flexible layer.

[0011] <Total Light Transmittance> The total light transmittance of the flexible layer 10 is preferably 20% or more. When the total light transmittance of the flexible layer 10 is 20% or more, light can be sufficiently transmitted through the light-transmitting sheet 1, and information can be displayed more clearly on the light-transmitting sheet 1. From this perspective, the total light transmittance of the flexible layer 10 is more preferably 25% or more, and even more preferably 30% or more. The upper limit of the range of the total light transmittance of the flexible layer 10 is not particularly limited, but the total light transmittance of the flexible layer 10 is usually 80% or less, preferably 70% or less. The total light transmittance of the flexible layer and the total light transmittance of the region of the flexible layer 10 where the light-shielding wall 20 described below is provided can be measured, for example, using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH8000") in accordance with ASTM D1003.

[0012] <Thickness> The thickness of the flexible layer 10 is preferably 0.5 mm or more. By making the thickness of the flexible layer 10 0.5 mm or more, the light-transmitting sheet tends to have a soft feel. From this perspective, the thickness of the flexible layer 10 is more preferably 0.7 mm or more, and even more preferably 1.0 mm or more. Furthermore, the thickness of the flexible layer 10 is preferably 5 mm or less. By making the thickness of the flexible layer 10 5 mm or less, the total light transmittance of the light-transmitting sheet tends to be increased. From this perspective, the thickness of the flexible layer 10 is preferably 4 mm or less, and more preferably 3 mm or less.

[0013] The flexible layer 10 is, for example, any one of a foam layer, a rubber layer, or a gel layer. The flexible layer 10 is preferably a foam layer having an Asker C hardness of 70 or less, a rubber layer having a JIS-A hardness of 45 or less, or a gel layer having a penetration of 10 or more and 150 or less. This gives the light-transmitting sheet 1 a soft feel.

[0014] (Foam Layer) When the flexible layer 10 is a foam layer, the Asker C hardness of the foam layer is preferably 70 or less. An Asker C hardness of 70 or less of the foam layer can impart a sufficiently soft feel to the light-transmitting sheet. From this perspective, the Asker C hardness of the foam layer is more preferably 65 or less, even more preferably 60 or less, and even more preferably 55 or less. While the lower limit of the Asker C hardness range is not particularly limited, from the viewpoint of maintaining a certain level of mechanical strength, the Asker C hardness of the foam layer is preferably 5 or more, more preferably 10 or more. The Asker C hardness of the foam layer can be adjusted by the thickness of the foam layer, the expansion ratio, etc. The Asker C hardness of the foam layer can be measured, for example, using an Asker Rubber Hardness Tester Type C (manufactured by Kobunshi Keiki Co., Ltd.) by contacting the indenter of the hardness tester with the foam layer at room temperature (23°C).

[0015] <Expansion Ratio> The expansion ratio of the foam layer is not particularly limited, but is preferably 5 times or more. When the expansion ratio is 5 times or more, the light-transmitting sheet tends to have a soft feel, and the total light transmittance of the foam layer can be easily adjusted to the above range. From this perspective, the expansion ratio of the foam layer is more preferably 7 times or more, and even more preferably 10 times or more. Furthermore, the expansion ratio of the foam layer is preferably 40 times or less. By setting the expansion ratio of the foam layer to 40 times or less, the mechanical strength of the foam layer can be maintained at a certain level or higher. From this perspective, the expansion ratio of the foam layer is more preferably 35 times or less, and even more preferably 30 times or less. The expansion ratio can be calculated by dividing the density of the foam precursor before foaming by the density (apparent density) of the foam after foaming. The apparent density can be measured in accordance with JIS K7222:2005.

[0016] <Closed Cell Ratio> The foam constituting the foam layer may be either an open-cell foam or a closed-cell foam. However, from the viewpoints of mechanical strength, watertightness, etc., the foam constituting the foam layer is preferably a closed-cell foam. A closed-cell foam means that the ratio of closed cells to the total cells of the foam (referred to as the closed cell ratio) is 65% or more, and an open-cell foam means that the closed cell ratio is less than 65%. The closed cell ratio was measured as follows. A test piece having a flat square shape with a side length of 5 cm and a constant thickness was cut out from a crosslinked polyolefin resin foam sheet. The thickness of the test piece was measured, and the apparent volume V1 of the test piece was calculated, and the weight W1 of the test piece was also measured. Next, the apparent volume V2 occupied by the cells was calculated according to the following formula. The density of the resin constituting the test piece was 1 g / cm. ３ The apparent volume occupied by the bubbles is V2 = V1 - W1. Next, the test piece is submerged in distilled water at 23°C to a depth of 100 mm from the water surface, and a pressure of 15 kPa is applied to the test piece for 3 minutes. After this, the test piece is removed from the water, the water adhering to the surface of the test piece is removed, the weight W2 of the test piece is measured, and the open cell fraction F1 and closed cell fraction F2 are calculated based on the following formulas: Open cell fraction F1 (%) = 100 × (W2 - W1) / V2 Closed cell fraction F2 (%) = 100 - F1 The closed cell fraction of the foam layer is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. The upper limit of the range of the closed cell fraction of the foam layer is 100%.

[0017] <Materials> The foam layer is preferably formed from a resin. Specific examples include a polyolefin foam layer, a urethane foam layer, and an acrylic foam layer. Of these, a polyolefin foam layer is preferred. The polyolefin foam layer is formed by foaming a foamable resin composition containing a polyolefin resin. Examples of polyolefin resins include polypropylene resin, polyethylene resin, and ethylene-vinyl acetate copolymer. These may be used alone or in a mixture of two or more. Of these, a polypropylene resin is preferred. The foam layer is preferably formed from only one type of resin. Using only one type of resin reduces the occurrence of fogging due to blending and increases the light transmittance of the foam layer. The foam layer may be a single-layer foam layer or a multi-layer foam layer formed by laminating two or more foams. The individual foams constituting the multi-layer foam layer may have different physical properties such as composition, thickness, total light transmittance, expansion ratio, and degree of crosslinking. It is preferred that the multi-layer foam layer as a whole satisfy the above physical properties.

[0018] When the foam layer is a polyolefin-based foam layer, the foam layer is preferably a crosslinked polyolefin-based foam layer (crosslinked polyolefin-based foam layer). A method for crosslinking the foam layer includes, for example, irradiating the foamable sheet with ionizing radiation such as electron beams, α-rays, β-rays, and γ-rays. Among these ionizing radiations, it is more preferable that the foam layer be crosslinked by electron beams. Details of crosslinking by electron beams will be described later in the description of the method for producing the foam layer.

[0019] <Polyethylene resin> As the polyethylene resin, low-density polyethylene resin (0.93 g / cm ３ hereinafter referred to as LDPE), medium density polyethylene resin (0.930 g / cm ３ Greater than 0.942 g / cm ３ less than MDPE), high density polyethylene resin (0.942 g / cm ３ A specific example of a suitable low-density polyethylene resin is linear low-density polyethylene (LLDPE).

[0020] The polyethylene resin may be an ethylene homopolymer, or may be a copolymer of ethylene and a small amount of an α-olefin, with ethylene as the main component (preferably 75% by mass or more, more preferably 90% by mass or more of all monomers). The α-olefin preferably has 3 to 12 carbon atoms, more preferably 4 to 10 carbon atoms, and specific examples include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, and 1-octene. In the copolymer, these α-olefins can be used alone or in combination of two or more. The polyethylene resin may be used alone or in combination of two or more types.

[0021] <Polypropylene Resin> Examples of polypropylene resins include homopolypropylene, which is a homopolymer of propylene, and copolymers of propylene with small amounts of ethylene and α-olefins other than propylene, with propylene as the main component (preferably 75% by mass or more, more preferably 90% by mass or more of all monomers). Examples of copolymers of propylene with α-olefins other than ethylene and propylene include block copolymers (block polypropylene), random copolymers (random polypropylene), and random block copolymers. Examples of α-olefins other than propylene include α-olefins having approximately 4 to 10 carbon atoms, such as 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, and 1-octene. Among these, ethylene is preferred from the viewpoints of moldability and heat resistance. In the copolymers, these α-olefins can be used alone or in combination of two or more. Furthermore, polypropylene resins can be used alone or in combination of two or more.

[0022] In the present invention, any of polyethylene resins, polypropylene resins polymerized with a polymerization catalyst such as a Ziegler-Natta compound, a metallocene compound, or a chromium oxide compound, or a mixture thereof may be used.

[0023] <Ethylene-vinyl acetate copolymer> Examples of the ethylene-vinyl acetate copolymer used as the polyolefin resin include an ethylene-vinyl acetate copolymer containing 50% by mass or more of structural units derived from ethylene. Since the ethylene-vinyl acetate copolymer has high compatibility with polyethylene resins and polypropylene resins, the ethylene-vinyl acetate copolymer can also be used in combination with one or more resins selected from polyethylene resins and polypropylene resins. The density of the ethylene-vinyl acetate copolymer is preferably 0.92 g / cm ３ More preferably, 0.93 g / cm ３ More preferably, 0.94 g / cm ３ and preferably 0.97 g / cm ３ or less, more preferably 0.96 g / cm ３ The following is the result.

[0024] The polyolefin foam layer may be composed solely of the above-mentioned polyolefin resin, or may be a mixture of a polyolefin resin and an elastomer. Examples of the elastomer include ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber (EPM), and styrene rubber. Examples of the elastomer also include thermoplastic elastomers. Examples of the thermoplastic elastomer include olefin-based thermoplastic elastomers and styrene-based thermoplastic elastomers. The content of the polyolefin resin in the polyolefin foam layer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, based on the total mass of the foam layer.

[0025] <Crosslinking degree (gel fraction)> The crosslinking degree (gel fraction) of the polyolefin foam layer is preferably 5 to 60% by mass. When the gel fraction is equal to or greater than the lower limit, sufficient crosslinking is formed in the foam layer, which tends to increase the mechanical strength. When the crosslinking degree is equal to or less than the upper limit, a soft feel is easily ensured. From this perspective, the crosslinking degree is more preferably 10 to 50% by mass, and even more preferably 10 to 40% by mass. The crosslinking degree can be measured by the measurement method described below.

[0026] (Production of Foam Layer) The foam layer is formed by foaming the foamable resin composition. Examples of foaming methods include a method using a foaming agent such as a thermal decomposition type foaming agent or water, as described below, and a method using an inert gas such as carbon dioxide or butane gas.

[0027] (Production of Polyolefin-Based Foam Layer) The polyolefin-based foam layer is produced, for example, by foaming a foamable resin composition containing the above-mentioned polyolefin resin and a foaming agent, etc. Examples of the foaming agent include chemical foaming agents and physical foaming agents.

[0028] <Blowing Agent> As the chemical blowing agent, a thermally decomposable blowing agent is preferred. As the thermally decomposable blowing agent, organic blowing agents and inorganic blowing agents can be used. Examples of organic blowing agents include azo compounds such as azodicarbonamide, azodicarboxylic acid metal salts (e.g., barium azodicarboxylate), and azobisisobutyronitrile; nitroso compounds such as N,N'-dinitrosopentamethylenetetramine; hydrazine derivatives such as hydrazodicarbonamide, 4,4'-oxybis(benzenesulfonylhydrazide), and toluenesulfonylhydrazide; and semicarbazide compounds such as toluenesulfonylsemicarbazide. Examples of inorganic blowing agents include ammonium carbonate, sodium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonium nitrite, sodium borohydride, and anhydrous monosodium citrate. Among these, azo compounds are preferred, and azodicarbonamide is more preferred, from the viewpoints of obtaining fine bubbles, economy, and safety. The thermal decomposition type foaming agent may be used alone or in combination of two or more. Examples of the physical foaming agent include an inert gas, which will be described later.

[0029] The content of the foaming agent in the foamable resin composition is preferably 1 to 30 parts by mass, more preferably 2 to 25 parts by mass, and even more preferably 2 to 20 parts by mass, per 100 parts by mass of the polyolefin resin. By incorporating the foaming agent in an amount of 1 part by mass or more, the foam layer can be appropriately foamed and can be imparted with a certain degree of flexibility. Furthermore, by incorporating the foaming agent in an amount of 30 parts by mass or less, the foam layer can be prevented from foaming more than necessary, and the mechanical strength of the foam layer can be improved.

[0030] <Nucleating Agent> The foamable resin composition may contain a nucleating agent. The nucleating agent is not particularly limited as long as it has the effect of increasing the rate of progress of the crystal nucleation process. Adding a nucleating agent to a polyolefin resin such as a polyethylene resin or a polypropylene resin can reduce the size of the resulting crystals, thereby improving the transparency of the foam layer. Examples of nucleating agents that have the effect of increasing the rate of progress of the crystal nucleation process include substances that promote molecular chain orientation through the adsorption process of polymer molecular chains. More specific examples include high-melting point polymers, organic carboxylic acids or metal salts thereof, aliphatic alcohols, dibenzylidene sorbitol or derivatives thereof, partial metal salts of rosin acid, amide compounds, inorganic fine particles, organic phosphoric acid compounds or metal salts thereof, imides, quinacridones, quinones, aromatic sulfonates or metal salts thereof, sugars, and mixtures thereof. These may be used alone or in combination of two or more.

[0031] <Additives> The foamable resin composition may contain components such as a crosslinking aid, a decomposition temperature regulator, and an antioxidant. A polyfunctional monomer can be used as the crosslinking aid. By adding the crosslinking aid to the polyolefin resin, the amount of electron beam irradiated in the step (2) described below can be reduced, thereby preventing scission and deterioration of resin molecules due to electron beam irradiation. Specific examples of the crosslinking aid include compounds having three functional groups in one molecule, such as trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, trimellitic acid triallyl ester, 1,2,4-benzenetricarboxylic acid triallyl ester, and triallyl isocyanurate, compounds having two functional groups in one molecule, such as 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, and divinylbenzene, diallyl phthalate, diallyl terephthalate, diallyl isophthalate, ethylvinylbenzene, neopentyl glycol dimethacrylate, lauryl methacrylate, and stearyl methacrylate. These crosslinking aids may be used alone or in combination of two or more.

[0032] The amount of the cross-linking aid added is preferably 0.5 to 10 parts by mass, more preferably 1.0 to 8 parts by mass, and even more preferably 1.5 to 5 parts by mass, per 100 parts by mass of the polyolefin resin. By adding an amount of 0.5 part by mass or more, it becomes possible to stably obtain a desired degree of cross-linking in the foam layer, and by adding an amount of 10 parts by mass or less, it becomes easy to control the degree of cross-linking in the foam layer.

[0033] The foamable resin composition may contain a decomposition temperature regulator. The decomposition temperature regulator is added to lower the decomposition temperature of the thermally decomposable foaming agent or to accelerate or adjust the decomposition rate, and specific examples of such compounds include zinc oxide, zinc stearate, and urea. The decomposition temperature regulator is added in an amount of, for example, 0.01 to 5 parts by mass per 100 parts by mass of the polyolefin resin in order to adjust the surface condition of the foam layer, etc.

[0034] The foamable resin composition may contain an antioxidant. Examples of antioxidants include phenol-based antioxidants such as 2,6-di-t-butyl-p-cresol and pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], sulfur-based antioxidants such as dilauryl thiodipropionate, phosphorus-based antioxidants, and amine-based antioxidants. The antioxidant is blended in an amount of, for example, 0.01 to 5 parts by mass per 100 parts by mass of the polyolefin resin. In addition to these, the foamable resin composition may also contain additives commonly used in foams, such as heat stabilizers, colorants, flame retardants, antistatic agents, and fillers.

[0035] (Rubber Layer) When the flexible layer 10 is a rubber layer, the JIS-A hardness of the rubber layer is preferably 45 or less. When the JIS-A hardness of the rubber layer is 45 or less, a sufficiently soft feel can be imparted to the light-transmitting sheet. From this perspective, the JIS-A hardness of the rubber layer is more preferably 40 or less, even more preferably 35 or less, and even more preferably 30 or less. Furthermore, although there is no particular restriction on the lower limit of the range of the JIS-A hardness of the rubber layer, from the viewpoint of maintaining a certain level of mechanical strength, the JIS-A hardness of the rubber layer is preferably 5 or more, more preferably 7 or more. The JIS-A hardness of the rubber layer is most preferably 9 or more and 11 or less. The JIS-A hardness of the rubber layer can be measured using a Type A durometer in accordance with JIS K 6253:2023.

[0036] Examples of rubber constituting the rubber layer include silicone rubber, urethane rubber, nitrile rubber, acrylic rubber, fluororubber, chloroprene rubber, ethylene propylene rubber, styrene rubber, polybutadiene rubber, butyl rubber, polyisobutylene, styrene-based thermoplastic elastomer, olefin-based thermoplastic elastomer, urethane-based thermoplastic elastomer, etc. The rubber to be used may be a rubber-like elastic material crosslinked with a crosslinking agent, or may be uncrosslinked raw rubber.

[0037] (Gel Layer) When the flexible layer 10 is a gel layer, the penetration depth of the gel layer is preferably 10 or more and 150 or less. A penetration depth of the gel layer of 10 or more can impart a sufficiently soft feel to the light-transmitting sheet. From this perspective, the penetration depth of the gel layer is more preferably 30 or more, even more preferably 50 or more, and even more preferably 60 or more. Furthermore, a penetration depth of the gel layer of 150 or less can further increase the mechanical strength of the light-transmitting sheet. From this perspective, the penetration depth of the gel layer is more preferably 140 or less, even more preferably 130 or less, and even more preferably 120 or less. The penetration depth of the gel layer can be measured in accordance with JIS K 2207:2006. The penetration depth is measured using a needle having a shape specified in the standard, with a total weight of the needle and needle fixture of 50 g and a weight of 50 g (i.e., a weight of 100 g on the sample), and is measured at 25°C when the needle is inserted vertically into the sample for 5 seconds. The needle penetration length of 0.1 mm is represented as 1.

[0038] Examples of gels that make up the gel layer include silicone gel, urethane gel, acrylic gel, styrene rubber, polyolefin gel, and hydrogel. Of these, silicone gel is preferred. The silicone gel that makes up the gel layer is not particularly limited, but is preferably a gel-like material obtained by controlling the crosslink density of addition-type liquid silicone rubber to 1 / 5 to 1 / 10 of normal levels and hardening it. An example of a suitable silicone gel is "Pantel GEL" manufactured by Sekisui Polymatech Co., Ltd.

[0039] The addition-type liquid silicone rubber used to prepare the silicone gel contains a vinyl group-containing organopolysiloxane as the base agent, a hydrogen organopolysiloxane as the crosslinking agent, and a platinum compound as the catalyst.

[0040] There are no particular restrictions on the viscosity of the vinyl group-containing organopolysiloxane, but in order to improve the handling of the silicone rubber composition obtained by mixing the silicone gel raw materials and the strength and fluidity of the resulting silicone gel, the viscosity at 23°C is preferably 50 to 100,000 mPa·s, and more preferably 100 to 10,000 mPa·s. The viscosity can be measured using a rotational viscometer.

[0041] To increase strength, the addition-type liquid silicone rubber may further contain a reinforcing material such as reinforcing silica, quartz powder, iron oxide, alumina, or vinyl group-containing silicone resin.

[0042] The addition-type liquid silicone rubber may further contain additives such as colorants such as pigments and dyes, release agents, heat resistance agents, flame retardants, flow control agents, anti-settling agents, and adhesion improvers.

[0043] (Light-shielding wall) The light-shielding wall 20 extends in the thickness direction of the flexible layer 10 and blocks light passing through the flexible layer 10. This makes it possible to prevent a display area that is not to be displayed from being displayed due to light leakage from the light source.

[0044] The hardness of the material constituting the light-shielding wall 20 is preferably equal to or smaller than the hardness of the material constituting the flexible layer 10. The Asker C hardness of the material constituting the light-shielding wall 20 is preferably 70 or less. If the Asker C hardness of the material constituting the light-shielding wall 20 is 70 or less, the soft feel of the light-transmitting sheet 1 can be prevented from being impaired by the light-shielding wall 20. From this perspective, the Asker C hardness of the light-shielding wall 20 is more preferably 65 or less, even more preferably 60 or less, and even more preferably 55 or less. Furthermore, although there is no particular restriction on the lower limit of the range of the Asker C hardness of the material constituting the light-shielding wall 20, the Asker C hardness of the material constituting the light-shielding wall 20 is preferably 5 or more, and more preferably 10 or more.

[0045] The JIS-A hardness of the material constituting the light-shielding wall 20 is preferably 45 or less. If the JIS-A hardness of the material constituting the light-shielding wall 20 is 45 or less, it is possible to prevent the soft feel of the light-transmitting sheet 1 from being impaired by the light-shielding wall 20. From this perspective, the JIS-A hardness of the material constituting the light-shielding wall 20 is more preferably 40 or less, even more preferably 35 or less, and even more preferably 30 or less. Furthermore, although there is no particular restriction on the lower limit of the range of the JIS-A hardness of the material constituting the light-shielding wall 20, the JIS-A hardness of the material constituting the light-shielding wall 20 is preferably 5 or more, and more preferably 7 or more.

[0046] The penetration of the material constituting the light-shielding wall 20 is preferably 10 or more. When the penetration of the material constituting the light-shielding wall 20 is 10 or more, the soft feel of the light-transmitting sheet 1 can be prevented from being impaired by the light-shielding wall 20. From this perspective, the penetration of the material constituting the light-shielding wall 20 is more preferably 30 or more, even more preferably 50 or more, and even more preferably 60 or more. Furthermore, the upper limit of the range of the penetration of the material constituting the light-shielding wall 20 is not particularly limited, but the penetration of the material constituting the light-shielding wall 20 is preferably 150 or less, more preferably 140 or less, even more preferably 130 or less, and even more preferably 120 or less.

[0047] The Asker C hardness of the material constituting the light-shielding wall 20 can be measured, for example, by using an Asker Rubber Hardness Tester Type C (manufactured by Kobunshi Keiki Co., Ltd.) to contact the indenter of the hardness tester at room temperature (23°C). The JIS-A hardness of the material constituting the light-shielding wall 20 can be measured using a Type A durometer in accordance with JIS K 6253:2023. The penetration depth of the material constituting the light-shielding wall 20 can be measured in accordance with JIS K 2207:2006. The penetration depth is the depth of penetration of a needle having a shape specified in the above standard, with the total weight of the needle and needle fixture being 50 g, and the weight of the weight being 50 g (i.e., the weight applied to the sample being 100 g), when the needle is inserted vertically into the sample for 5 seconds at 25°C. 0.1 mm of the needle penetration length is represented as 1.

[0048] The material constituting the light-shielding wall 20 may be any light-shielding material, such as a light-shielding ink containing a colorant. However, preferred examples include materials that can be used for the flexible layer 10 but are colored with a colorant. The material constituting the light-shielding wall 20 is preferably rubber or gel, more preferably gel, and even more preferably silicone gel. Using rubber or gel as the material constituting the light-shielding wall 20 can further prevent the flexible layer from losing its flexibility due to the provision of the light-shielding wall 20. Furthermore, the gel can be easily filled into the grooves formed for providing the light-shielding wall 20. Furthermore, the material constituting the light-shielding wall 20 may be a light-shielding adhesive. Using a light-shielding adhesive as the material constituting the light-shielding wall 20 allows the light-shielding wall 20 to connect and fix the flexible layer 10. Examples of colorants for coloring the material constituting the light-shielding wall 20 include white colorants such as titanium oxide, black colorants such as carbon black, and colored colorants other than white or black, such as quinacridone red pigments and phthalocyanine blue. The content of the colorant in the material constituting the light-shielding wall 20 is preferably 1 to 35 mass %, more preferably 5 to 30 mass %, based on the total mass of the light-shielding wall. Furthermore, the colorant is preferably a black colorant such as carbon black.

[0049] The total light transmittance in the region of the flexible layer 10 where the light-shielding wall 20 is provided is preferably 5% or less. If the total light transmittance in the region of the flexible layer 10 where the light-shielding wall 20 is provided is 5% or less, light leakage from the light source can be further suppressed. From this perspective, the total light transmittance in the region of the flexible layer 10 where the light-shielding wall 20 is provided is more preferably 4% or less, and even more preferably 3% or less. The lower the total light transmittance in the region of the flexible layer 10 where the light-shielding wall 20 is provided, the better, and it is sufficient if it is 0% or more.

[0050] The length h of the light-shielding wall 20 in the thickness direction of the flexible layer 10 is preferably 50% or more of the thickness of the flexible layer 10. When the length h of the light-shielding wall 20 in the thickness direction is 50% or more of the thickness of the flexible layer 10, light leakage from the light source can be further suppressed. From this perspective, the length h of the light-shielding wall 20 in the thickness direction is more preferably 55% or more of the thickness of the flexible layer 10, and even more preferably 60% or more of the thickness of the flexible layer 10. The upper limit of the range of the length h of the light-shielding wall 20 in the thickness direction is not particularly limited, but may be, for example, 100% of the thickness of the flexible layer 10. Note that when the length h of the light-shielding wall 20 in the thickness direction is 100% of the thickness of the flexible layer 10, the light-shielding wall 20 will penetrate the flexible layer 10. Furthermore, from the viewpoint of the soft feel of the light-transmitting sheet 1, the length h is preferably 90% or less of the thickness of the flexible layer 10, more preferably 80% or less of the thickness of the flexible layer 10, and even more preferably 75% or less of the thickness of the flexible layer 10. If the light-shielding wall 20 is 100% of the thickness of the flexible layer 10, it will penetrate the flexible layer 10, but by leaving some areas that are partially connected in the thickness or width direction, the flexible layers 10 will not come detached from each other and the spacing between the light-shielding walls 20 can be maintained.

[0051] The thickness t of the light-shielding wall 20 is not particularly limited as long as it is thinner than the distance between adjacent display regions (i.e., transmissive regions, which will be described later). The thickness of the light-shielding wall 20 is preferably 0.2 to 2.0 mm. When the thickness t of the light-shielding wall 20 is 0.2 mm or more, the light-shielding wall has better light-shielding properties. When the thickness t of the light-shielding wall 20 is 2.0 mm or less, the flexibility of the flexible layer 10 can be further prevented from being hindered by the light-shielding wall 20. From this perspective, the thickness t of the light-shielding wall 20 is more preferably 0.3 to 1.8 mm, and even more preferably 0.5 to 1.5 mm.

[0052] An example of a method for forming the light-shielding wall 20 will be described with reference to Figure 2(a). As shown in Figure 2(a), laser light is irradiated onto the flexible layer 10 from a processing nozzle 30 of a laser processing machine, and grooves 11 are formed in the flexible layer 10 as shown in Figure 2(b). However, the formation of the grooves 11 is not limited to laser irradiation and may be performed by other known means, for example, the grooves 11 may be formed using a blade. Then, as shown in Figure 2(c), the light-shielding wall can be formed by filling the grooves in the flexible layer 10 with a material 21 that constitutes the light-shielding wall.

[0053] (Light-Shielding Layer) As shown in FIG. 3 , the light-transmitting sheet 1A of one embodiment of the present invention may further include a light-shielding layer 40 that blocks light transmitted through the flexible layer 10. This allows the light-transmitting sheet 1A of one embodiment of the present invention to have a transmissive region L that transmits light in the thickness direction and a light-shielding region D that blocks light. The light-transmitting sheet 1A of one embodiment of the present invention can display information according to a pattern formed by the transmissive region L and the light-shielding region D by transmitting light from a light source. It is preferable that the light-shielding region D is a region where the light-shielding layer 40 is provided, and the transmissive region L is a region where the light-shielding layer 40 is not provided. However, it is preferable that the transmissive region L is formed by an opening 41 formed in the light-shielding layer 40. Furthermore, it is preferable that the light-shielding layer 40 is positioned so as to overlap the light-shielding wall 20 when viewed in the thickness direction, and that the light-shielding wall 20 is hidden by the light-shielding layer 40 when viewed from the light-shielding layer 40 side.

[0054] The distance w between adjacent transmission regions between which the light-shielding wall 20 is disposed is not particularly limited, but is, for example, about 0.5 to 30 mm, preferably 1 to 15 mm, and more preferably 2 to 10 mm.

[0055] The light-shielding layer is preferably a printed layer or a printed film layer. The printed layer can be formed, for example, by printing on the surface of at least one of the flexible layer and the skin layer described below. The printed film layer is formed by forming a printed layer on a base film such as a polyolefin film or a polyester film such as a PET film. As a method for forming the printed layer, known methods such as an inkjet method or screen printing can be appropriately used. The thickness of the printed layer is preferably 1 to 25 μm, more preferably 2 to 10 μm. The thickness of the printed film layer is preferably 50 to 125 μm, more preferably 50 to 100 μm.

[0056] The flexible layer 10 and the light-shielding layer 40 may be laminated by a thermal lamination method, or the layers may be bonded together using a bonding material or adhesive.

[0057] (Surface Layer) As shown in FIG. 4 , the light-transmitting sheet 1B of one embodiment of the present invention may further include a light-transmitting surface layer 50. This can further improve the design of the light-transmitting sheet 1B. The material constituting the surface layer 50 is not particularly limited, but examples include resin sheets such as polypropylene sheets, polyethylene sheets, olefin-based thermoplastic elastomer (TPO) sheets, polyvinyl chloride sheets, and mixed resin sheets of polyvinyl chloride and ABS resin; cloths such as woven fabrics, knitted fabrics, and nonwoven fabrics made from natural or artificial fibers; and synthetic surface layers such as artificial leather and synthetic leather. Among these materials, cloth and synthetic surface layers are preferred for the surface layer 50 from the viewpoint of achieving high design quality.

[0058] The thickness of the skin layer 50 is preferably 0.1 to 2.0 mm. If the thickness of the skin layer 50 is 0.1 mm or more, the skin layer 50 can achieve even higher designability. If the thickness of the skin layer 50 is 2.0 mm or less, the flexibility of the light-transmitting sheet 1B caused by the flexible layer 10 can be prevented from being hindered by the skin layer 50. From this perspective, the thickness of the skin layer 50 is more preferably 0.2 to 1.5 mm, and even more preferably 0.3 to 1.0 mm.

[0059] The surface layer 50 may contain a pigment such as carbon black, titanium dioxide, pearl particles, or metal powder such as aluminum powder, from the viewpoint of adjusting the color of the surface layer 50. The content of the pigment in the surface layer 50 is preferably 0.01 to 3 mass %, and more preferably 0.02 to 1 mass %, based on the total mass of the surface layer.

[0060] The total light transmittance of the surface layer 50 is preferably 0.02% or more. When the total light transmittance of the surface layer 50 is 0.02% or more, light can be sufficiently transmitted through the light-transmitting sheet 1, and information can be displayed more clearly on the light-transmitting sheet 1. From this perspective, the total light transmittance of the surface layer 50 is more preferably 1% or more. The upper limit of the range of the total light transmittance of the surface layer 50 is not particularly limited, but the total light transmittance of the surface layer 50 is usually 30% or less, preferably 25% or less. The total light transmittance of the surface layer 50 can be measured, for example, using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH8000") in accordance with ASTM D1003.

[0061] The flexible layer 10 and the skin layer 50 may be laminated by a thermal lamination method, or the layers may be bonded together using a bonding material or adhesive.

[0062] As shown in FIG. 5 , a light-transmitting sheet 1C according to one embodiment of the present invention may further include a surface layer 50 and a light-shielding layer 40 disposed between the flexible layer 10 and the surface layer 50 .

[0063] The flexible layer 10, the light-shielding layer 40, and the surface layer 50 may be laminated by a thermal lamination method, or the layers may be bonded together using a bonding material or adhesive.

[0064] (Other Layers) The light-transmitting sheet of the present invention may further include layers other than the above-described layers, provided that the effects of the present invention are not impaired.

[0065] [Modification of Light-Transmitting Sheet] The light-shielding walls 20 of the light-transmitting sheet 1 according to one embodiment of the present invention have a structure in which the interior is filled with the material that constitutes the light-shielding walls 20. However, the light-shielding walls may have a hollow structure. This further prevents the light-shielding walls from impairing the soft feel of the flexible layer. For example, as in the light-transmitting sheet 1D shown in FIG. 6, the light-shielding walls 20D may be formed by a coating film 22 formed on the surface of recesses 12 formed on the surface of the flexible layer 10. In this case, the provision of the light-shielding walls 20D further reduces the likelihood of impairing the flexibility of the light-transmitting sheet 1D.

[0066] The coating film 22 preferably contains a binder component and a colorant. Examples of binder components include polyurethane resins, vinyl chloride resins such as vinyl chloride-vinyl acetate copolymers and vinyl chloride-vinyl acetate-acrylic copolymers, polyolefin resins such as chlorinated polypropylene resins, acrylic resins, polyester resins, polyamide resins, styrene resins such as butyral resins and ABS resins, and cellulose resins such as nitrocellulose resins and cellulose acetate resins. These resins can be used alone or in combination of two or more. From the viewpoint of the feel of the light-transmitting sheet, polyurethane resins or polyester resins are preferred.

[0067] The content of the binder component in the coating film 22 is not particularly limited, but is preferably 60 to 99% by mass, more preferably 65 to 97% by mass, and even more preferably 70 to 95% by mass, relative to 100% by mass of the total amount of the coating film 22. When the content of the binder component is 60% by mass or more, the adhesion of the coating film 22 to the flexible layer 10 is further improved. When the content of the binder component is 99% by mass or less, the colorant can be sufficiently blended into the coating film 22.

[0068] The same coloring agents as those used to color the material that constitutes the light-shielding wall 20 as described above can be used as the coloring agent contained in the coating film 22 .

[0069] The content of the colorant in the coating film 22 is preferably 1 to 40% by mass, more preferably 3 to 35% by mass, and even more preferably 5 to 30% by mass, relative to 100% by mass of the total amount of the coating film 22. When the content of the colorant is 1% by mass or more, the light-blocking properties of the coating film 22 are further improved. When the content of the colorant is 40% by mass or less, the adhesion of the coating film 22 to the flexible layer 10 is further improved.

[0070] The coating film 22 may contain other components in addition to the binder component and the colorant. Examples of other components include processing aids, reinforcing agents, flame retardants, antifoaming agents, leveling agents, crosslinking agents, silane coupling agents, thixotropic agents, tackifiers, waxes, stabilizers such as heat stabilizers, light resistance improvers, UV absorbers, weather resistance improvers, fluorescent brighteners, conductivity improvers, antistatic agents, moisture permeability improvers, water repellents, oil repellents, foaming agents, crystal water-containing compounds, water absorbers, moisture absorbers, deodorizers, foam stabilizers, antifogging agents, antifungal agents, preservatives, anti-algae agents, pigment dispersants, inert gases, slip agents, lubricants, antiblocking agents, hydrolysis inhibitors, neutralizers, natural oils, synthetic oils, and thickeners. These other components may be used alone or in combination of two or more.

[0071] The thickness of the coating film 22 is preferably 0.001 to 0.01 mm, more preferably 0.003 to 0.01 mm, and even more preferably 0.005 to 0.02 mm. When the thickness of the coating film 22 is 0.001 mm or more, the light-blocking properties of the coating film 22 are further improved. Furthermore, even when the thickness of the coating film 22 is 0.01 mm or less, the light-blocking properties of the coating film 22 are excellent.

[0072] An example of a method for forming the light-shielding wall 20D will be described with reference to FIG. 7( a). As shown in FIG. 7( a), laser light is irradiated onto the flexible layer 10 from the processing nozzle 30 of a laser processing machine. Then, as shown in FIG. 7( b), grooves 12 are formed in the flexible layer 10. However, the formation of the grooves 12 is not limited to laser irradiation and may be performed by other known means, for example, the grooves 12 may be formed using a blade. Then, as shown in FIG. 7( c), the light-shielding wall can be formed by applying paint 23 made of a material that constitutes the light-shielding wall to the surface of the grooves 12 in the flexible layer 10. The paint 23 can be applied, for example, by an inkjet method or by printing, such as dispense coating, brush coating, or spatula coating.

[0073] Another example of a method for forming a light-shielding wall 20D will be described with reference to Fig. 8(a). As shown in Fig. 8(a), a coating material 24 is applied to the surface of the flexible layer 10. The coating material 24 can be applied by printing, such as an inkjet method or a screen printing method. Then, the surface of the flexible layer 10 is pressed with a jig such as a heated mold, and as shown in Fig. 8(b), recesses 13 are formed in the areas where the coating material 24 is applied, thereby forming the light-shielding wall.

[0074] The light-transmitting sheet according to one embodiment of the present invention and its modified examples are examples of the light-transmitting sheet of the present invention, and do not limit the light-transmitting sheet of the present invention.

[0075] [Optical Display Member] The light-transmitting sheet of the present invention can be suitably used as an optical display member. The optical display member of the present invention includes the light-transmitting sheet of the present invention and a light source. The configuration of the optical display member is not particularly limited, but for example, as shown in FIG. 9, an optical display member 100 can be formed by attaching a light source 2 to a light-transmitting sheet 1C. Here, the light source 2 may be attached directly to the light-transmitting sheet 1C, or the light source 2 may be attached to a resin substrate 60 to which the light-transmitting sheet 1C is attached. The resin constituting the resin substrate 60 is not particularly limited as long as it is a resin with optical transparency. Examples of resins constituting the resin substrate 60 include polymethyl methacrylate, polycarbonate, cycloolefin polymer, perfluororesin, transparent polyimide, epoxy resin, polyethylene terephthalate, and polyethylene. Examples of the light source 2 include a liquid crystal display (LCD), a light-emitting diode (LED), an organic EL element, and an inorganic EL element.

[0076] When the light-shielding wall 20 does not penetrate the flexible layer 10, as in the optical display device 100 shown in FIG. 9, the light source 2 may be arranged on the light-shielding wall side of the flexible layer 10, or, as in the optical display device 100A shown in FIG. 10, the light source 2 may be arranged on the opposite side of the flexible layer 10 from the light-shielding wall side, but it is preferable to arrange the light source 2 on the light-shielding wall side as shown in FIG. 9. This allows the light-shielding wall 20 to more appropriately block light from the light source 2. As a result, information corresponding to the pattern formed by the transmissive area and the light-shielding area can be displayed more clearly. Note that when the light-shielding wall penetrates the flexible layer, either surface side of the flexible layer will be referred to as the "light-shielding wall side."

[0077] 9, the light source 2 may be disposed on the opposite side of the flexible layer 10 from the light-shielding layer side, or on the light-shielding layer side of the flexible layer. However, it is preferable that the light source be disposed on the opposite side of the flexible layer from the light-shielding layer side. This allows information corresponding to the pattern formed by the transmissive and light-shielding regions to be displayed more clearly.

[0078] The light display element may include a sensor. Examples of sensors include electrostatic sensors, pressure-sensitive sensors, hover sensors, heat sensors, and vibration sensors. For example, by providing an electrostatic sensor and a pressure-sensitive sensor in the light display element, touch input to the light display element is possible. As a result, for example, a light effect can be initiated by touching the light display element. Furthermore, by providing an electrostatic sensor in the light display element, it is possible to detect the approach of a person to the light display element. As a result, for example, a light effect can be initiated when a person approaches the light display element. By providing a hover sensor in the light display element, it is possible to input to the light display element without contact. As a result, for example, a light effect can be initiated by bringing a hand close to the light display element. By providing a heat sensor in the light display element, it is possible to generate a light effect according to the indoor temperature, for example, a light effect according to the season. Furthermore, it is possible to generate a light effect to alert the user when the indoor temperature is too high or too low. By providing a vibration sensor in the light display element, it is possible to prevent theft of mobility. For example, when a vibration sensor detects vibration while the mobility is parked, a light can be emitted to alert those in the vicinity to theft. The light display member may also include a switch. Examples of switches include a mechanical switch and a membrane switch. By providing such a switch in the light display device, the light display can be started and stopped by the switch. The light display member may also include both a sensor and a switch. Electronic components other than sensors and switches may also be appropriately disposed in the light display member, for example, a heater may be disposed in the light display member. Examples of heaters include a seat heater in which a thermocouple or a metal layer is provided on a seat.

[0079] In the optical display member, the sensor may be disposed on the side opposite the light source side of the light-transmitting sheet, between the light-transmitting sheet and the light source, or between the skin layer and the light-shielding layer. The sensor is preferably a sheet-like member (sensor sheet) to facilitate placement on the light-transmitting sheet. The switch may also be disposed on the side opposite the light source side of the light-transmitting sheet, between the light-transmitting sheet and the light source, or between the skin layer and the light-shielding layer. However, by providing a light source on the back side of the switch, light from the light source can be transmitted to display switch information such as switch position information and switch operation information (up / down switch display, selection switch display, keyboard-like switch display, etc.). In other words, by locating the switch in a position illuminated by light from the light source, the switch position can be accurately indicated to the operator. Furthermore, the above-mentioned printed layer or printed film layer can be used to display switch information on the surface of the optical display member. Furthermore, electronic components other than sensors and switches may be located anywhere on the optical display member or the light-transmitting sheet.

[0080] The light display member is suitably used as an interior member for mobility such as automobiles, flying cars, airplanes, ships, etc. The interior member for mobility exhibits excellent design by the light leaking through the light-transmitting sheet of the present invention.

[0081] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0082] The evaluation method was as follows. <Evaluation of Light Leakage> As shown in Fig. 11 , on the surface of the light-transmitting sheet 1 on which the light-shielding wall 20 was formed, scales 25 were formed parallel to the light-shielding wall 20 at 1 mm intervals, with five scales on each side of the light-shielding wall 20. Then, at a position 5 mm away from the light-shielding wall 20, a top-emitting LED light source 200 (manufactured by ams-OSRAM, OSIRE (registered trademark) E3323 "KRTBDWLM31.32", emitting light with a brightness (luminous flux) of 5 lumens) mounted on a substrate was placed so that its irradiation port was in contact with the light-transmitting sheet 1. Then, in a darkroom, the LED light source 200 was turned on, and the extent of the spread of light leaking from the light-shielding wall 20 was visually measured based on the scales 25 and evaluated as follows: A: No light leakage from the light-shielding wall. B: The range of light leaking from the light-shielding wall is more than 0 mm and less than 1 mm. C: The range of light leaking from the light-shielding wall is 1 mm or more and less than 2 mm. D: The range of light leaking from the light-shielding wall is 2 mm or more and less than 3 mm. E: The range of light leaking from the light-shielding wall is 3 mm or more and less than 4 mm. F: The range of light leaking from the light-shielding wall is 4 mm or more and less than 5 mm. G: The range of light leaking from the light-shielding wall is 5 mm or more.

[0083] <Method of producing light-transmitting sheet> A light-transmitting foam (manufactured by Sekisui Chemical Co., Ltd., product name "VSW2002", cross-linked polyolefin closed-cell foam, thickness 2 mm, expansion ratio 20 times, Asker C hardness 50, closed-cell ratio 99%) was prepared. 100 parts by mass of silicone gel (manufactured by Sekisui Polymatech Co., Ltd., "Pantel GEL") and 1.0 part by mass of pigment masterbatch (manufactured by Momentive, "ME50-B") were kneaded to produce a black silicone gel (penetration 60). Using a laser processing machine (manufactured by Universal Laser Systems, model number "VLS4.60"), grooves having lengths in the thickness direction of the foam shown in Table 2 were formed on the surface of the foam. The grooves formed on the surface of the foam were filled with black silicone gel to form light-shielding walls (thickness 1.0 mm) in the foam, thereby producing a light-transmitting sheet.

[0084] The evaluation results are shown in Table 1.

[0085] By comparing Examples 1 to 7 with Comparative Example 1, it was found that the provision of a light-shielding wall can suppress light leakage from the light source.

[0086] REFERENCE SIGNS LIST 1, 1A to 1E Light-transmitting sheet 2 Light source 10 Flexible layer 11, 12 Groove 13 Recess 20, 20D Light-shielding wall 21 Material constituting the light-shielding wall 22 Coating film 23, 24 Paint 25 Scale 30 Processing nozzle 40 Light-shielding layer 50 Skin layer 60 Resin substrate 100 Optical display member 200 LED light source

Claims

1. A light-transmitting sheet comprising: a flexible layer having optical transparency; and a light-shielding wall located inside the flexible layer, extending in the thickness direction of the flexible layer, and blocking light passing through the flexible layer.

2. The light-transmitting sheet according to claim 1, further comprising a light-shielding layer that blocks light transmitted through the flexible layer.

3. The light-transmitting sheet according to claim 1, wherein the material constituting the light-shielding wall has an Asker C hardness of 70 or less, a JIS-A hardness of 45 or less, or a penetration of 10 or more.

4. The light-transmitting sheet according to claim 1, wherein the flexible layer is a foam layer having an Asker C hardness of 70 or less.

5. The light-transmitting sheet according to claim 1, wherein the flexible layer is a rubber layer having a JIS-A hardness of 45 or less.

6. The light-transmitting sheet according to claim 1, wherein the flexible layer is a gel layer having a penetration of 10 or more and 150 or less.

7. The light-transmitting sheet according to claim 1, wherein the length of said light-shielding wall in the thickness direction of said flexible layer is 50% or more of the thickness of said flexible layer.

8. The light-transmitting sheet according to claim 1, further comprising a surface layer having light-transmitting properties.

9. An optical display member comprising the light-transmitting sheet according to any one of claims 1 to 8 and a light source.

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