Decorative sheet, decorative member, and display system

Abstract

To improve the image quality of an image displayed in a display system.SOLUTION: A decorative sheet 20 comprises: a decorative layer 30 that comprises a substrate layer 31 and a design layer 32; and a bonding layer 40 laminated on the decorative layer 30 in a first direction D1. The design layer 32 is located between the substrate layer 31 and the bonding layer 40. The total light transmittance of the decorative sheet 20 is from 5.0% to 70% inclusive. The initial yellowness value of the bonding layer 40 is 2.00 or less, and the degree of yellowing of the bonding layer 40 is 3.50 or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a decorative sheet, a decorative member, and a display system. [Background technology]

[0002] A display system including a decorative sheet is known, as disclosed in Patent Document 1, for example. The display system includes a decorative sheet and a display device overlaid on the decorative sheet. The display system displays an image using light emitted from the display device and transmitted through the decorative sheet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-295365 Summary of the Invention [Problem to be solved by the invention]

[0004] The decorative sheet is attached to a display device via a bonding layer. It has been found that a problem may occur in a display system in which the quality of a displayed image is degraded due to light transmitted through the bonding layer. The present disclosure aims to provide a decorative sheet that can improve the quality of an image displayed in the display system. [Means for solving the problem]

[0005] A first decorative sheet according to an embodiment of the present disclosure includes: a decorative layer including a base layer and a design layer; A decorative sheet comprising: a bonding layer overlapping the decorative layer in a first direction; The design layer is located between the base layer and the bonding layer, The total light transmittance is 5.0% or more and 70% or less, The initial value of yellowness index of the bonding layer is 2.00 or less, and the yellowness index of the bonding layer is 3.50 or less.

[0006] The second decorative sheet according to an embodiment of the present disclosure includes: a decorative layer including a base layer and a design layer; A decorative sheet comprising: a bonding layer overlapping the decorative layer in a first direction; The design layer is located between the base layer and the bonding layer, The total light transmittance is 5.0% or more and 70% or less, The initial yellowness index is 10.0 or less, and the yellowing index is 3.50 or less.

[0007] A third decorative sheet according to an embodiment of the present disclosure includes: a decorative layer including a base layer and a design layer; A decorative sheet comprising: a bonding layer overlapping the decorative layer in a first direction; The design layer is located between the base layer and the bonding layer, The decorative layer has an uneven surface, the bonding layer is bonded to the uneven surface, The total light transmittance is 5.0% or more and 70% or less, The maximum length of the bonding layer in the first direction is 2.0 times or more the height difference of the uneven surface in the first direction. [Effects of the Invention]

[0008] According to the present disclosure, the quality of images displayed in a display system can be improved. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an exploded perspective view of a display system according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the display system of FIG. [Figure 3] FIG. 3 is a plan view of the display system of FIG. 1 including the display device in a non-display state. [Figure 4] FIG. 4 is a plan view of the display system of FIG. 1 including the display device in a display state. [Figure 5]FIG. 5 is an enlarged plan view of the decorative sheet included in the display system of FIG. [Figure 6] FIG. 6 is a cross-sectional view of the decorative sheet of FIG. [Figure 7] FIG. 7 is a diagram for explaining a method for manufacturing the decorative sheet shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view of a modified example of the decorative sheet. [Figure 9] FIG. 9 is a cross-sectional view of a modified example of the display system. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present disclosure relates to the following [1] to

[18] .

[0011] [1] A decorative layer including a base layer and a design layer; A decorative sheet comprising: a bonding layer overlapping the decorative layer in a first direction; The design layer is located between the base layer and the bonding layer, The total light transmittance is 5.0% or more and 70% or less, The decorative sheet, wherein the initial value of yellowness index of the bonding layer is 2.00 or less, and the yellowing index of the bonding layer is 3.50 or less.

[0012] [2] A decorative layer including a base layer and a design layer; A decorative sheet comprising: a bonding layer overlapping the decorative layer in a first direction; The design layer is located between the base layer and the bonding layer, The total light transmittance is 5.0% or more and 70% or less, A decorative sheet having an initial yellowness index of 10.0 or less and a yellowing index of 3.50 or less.

[0013] [3] The decorative layer has an uneven surface, the bonding layer is bonded to the uneven surface, The decorative sheet according to [1] or [2], wherein the maximum thickness of the bonding layer is 2.0 times or more the height difference of the uneven surface in the first direction.

[0014] [4] A decorative layer including a base layer and a design layer; A decorative sheet comprising: a bonding layer overlapping the decorative layer in a first direction; The design layer is located between the base layer and the bonding layer, The decorative layer has an uneven surface, the bonding layer is bonded to the uneven surface, The total light transmittance is 5.0% or more and 70% or less, The decorative sheet, wherein the maximum thickness of the bonding layer is 2.0 times or more the height difference of the uneven surface in the first direction.

[0015] [5] The decorative sheet according to [3] or [4], wherein the decorative layer includes a plurality of printed layers that form the uneven surface.

[0016] [6] The uneven surface includes a plurality of recesses that open toward the bonding layer, The decorative sheet according to any one of [3] to [5], wherein each of the plurality of recesses has a shape tapered toward the bottom of the recess.

[0017] [7] The decorative sheet according to any one of [1] to [6], wherein the storage modulus of the bonding layer at 25° C. is 1.0 MPa or less.

[0018] [8] The decorative sheet according to any one of [1] to [7], wherein the storage modulus of the bonding layer at 80° C. is 1.0 MPa or less.

[0019] [9] The decorative sheet according to any one of [1] to [8], wherein the total light transmittance of the bonding layer is 80% or more.

[0020]

[10] The decorative sheet according to any one of [1] to [9], wherein the transmission haze of the bonding layer is 2.0% or less.

[0021]

[11] The decorative sheet according to any one of [1] to

[10] , wherein the maximum thickness of the bonding layer is greater than the maximum thickness of the base layer.

[0022]

[12] The decorative layer includes a light-shielding layer having a light-shielding property, The decorative sheet according to any one of [1] to

[11] , wherein the light-shielding layer is located between the base layer and the bonding layer.

[0023]

[13] The decorative sheet according to any one of [1] to

[12] , wherein the maximum thickness of the bonding layer is 25.0 μm or more and 100 μm or less.

[0024]

[14] The decorative sheet according to any one of [1] to

[13] , wherein the bonding layer contains a cured resin.

[0025]

[15] The decorative sheet according to any one of [1] to

[14] , wherein the peel strength on the surface formed by the bonding layer is 10.0 N / 25 mm or more and 40.0 N / 25 mm or less.

[0026]

[16] a support member; A decorative member comprising a decorative sheet according to any one of [1] to

[15] superimposed on the support member.

[0027]

[17] A decorative sheet according to any one of [1] to

[15] . a display device overlaid on the decorative sheet, the decorative sheet has a first surface and a second surface opposite to the first surface, the first surface is formed by the bonding layer, the second surface is formed by the decorative layer, The decorative sheet is placed on the display device from the first surface side.

[0028]

[18] A decorative sheet according to any one of [1] to

[15] . a display device superimposed on the decorative sheet; a joint portion located between the decorative sheet and the display device, The bonding portion is bonded to the decorative sheet and the bonding portion, A display system wherein the initial yellowness index of the joint is 2.00 or less, and the yellowness index of the joint is 3.50 or less.

[0029] An embodiment will be described below with reference to the drawings. In the drawings, the scale and dimensional ratios are appropriately exaggerated from those of the actual objects in order to facilitate illustration and understanding. Note that configurations shown in some drawings may be omitted in other drawings.

[0030] Terms such as "sheet," "film," and "plate" are not distinguished from one another solely by the difference in their names. For example, a "decorative sheet" may be called a decorative film or a decorative plate.

[0031] Terms such as "orthogonal" and "identical" that specify shapes, geometric conditions, and their degrees are not limited to their strict meanings, and should be interpreted to include a range of degrees within which similar functions can be expected.

[0032] Directions common to the drawings are indicated by arrows with the same symbol in each drawing. In each direction, the tip of the arrow is the first side. In each direction, the side opposite the first side, i.e., the base of the arrow, is the second side. An arrow pointing from the front to the back of the paper in a direction perpendicular to the paper surface is indicated by a symbol with an X in a circle, as shown in Figure 2, for example. An arrow pointing from the back to the front of the paper in a direction perpendicular to the paper surface is indicated by a symbol with a dot in a circle, as shown in Figure 3, for example.

[0033] When multiple upper limit candidates and multiple lower limit candidates are listed for a certain parameter, the numerical range of the parameter may be constructed by combining any one upper limit candidate with any one lower limit candidate. For example, it may be written as follows: "Parameter B may be A1 or more, A2 or more, or A3 or more. Parameter B may be A4 or less, A5 or less, or A6 or less." In this example, the numerical range of parameter B may be A1 or more and A4 or less, A1 or more and A5 or less, A1 or more and A6 or less, A2 or more and A4 or less, A2 or more and A5 or less, A2 or more and A6 or less, A3 or more and A4 or less, A3 or more and A5 or less, or A3 or more and A6 or less.

[0034] 1 to 6 are diagrams illustrating an embodiment. FIG. 1 is an exploded perspective view of a display system 1. The display system 1 includes a display device 10 and a decorative sheet 20 superimposed on the display device 10 in a first direction D1. In the example shown in FIG. 2, the decorative sheet 20 is joined to the display device 10. The illustrated first direction D1 is the stacking direction of the display device 10 and the decorative sheet 20. The illustrated display system 1 is observed from a first side in the first direction D1. In the illustrated display system 1, the display device 10 is observed through the decorative sheet 20.

[0035] In the present disclosure, "bonding" includes "adhesion", "bonding" includes "adhesion", and "bonded" includes "adhered".

[0036] The display system 1 can be applied to various applications. The display system 1 can be applied to electrical appliances such as smartphones and tablets. The display system 1 can be applied to furniture such as refrigerators and washing machines. The display system 1 can be applied to a mobile object. The mobile object is a device that can move. The mobile object can be one or more of an automobile, a ship, an airplane, and a drone. The display system 1 can be applied to the interior material of the mobile object, or the exterior material of the mobile object.

[0037] 1 and 2, the display device 10 includes a display surface 11 facing a first side in a first direction D1. The display surface 11 faces a viewer of the display system 1. In the illustrated display device 10, the display surface 11 has a length direction in a second direction D2 that is perpendicular to the first direction D1. The display surface 11 has a width direction in a third direction D3 that is perpendicular to both the first direction D1 and the second direction D2.

[0038] As shown in FIG. 4, the display device 10 emits image light in the display state. The image light is emitted from a display surface 11. The display device 10 may display a still image in the display state. In the example shown in FIG. 4, the character string "ABC" is displayed by the image light emitted from the display device 10. Unlike the example shown, the display device 10 may display a moving image in the display state. As shown in FIG. 3, the display device 10 stops emitting image light in the non-display state. In the display device 10 in the non-display state, the display surface 11 may be black. The display device 10 may be one or more of a liquid crystal display, a plasma display, and an organic electroluminescence (EL) display.

[0039] 1, 2, and 5, the decorative sheet 20 includes a first surface 20a and a second surface 20b opposite the first surface 20a. The first surface 20a and the second surface 20b face each other in a first direction D1. In the example shown in FIG. 2, the decorative sheet 20 is bonded to an adherend AB from the first surface 20a. In the display system 1 shown in FIG. 1, the display device 10 is the adherend AB of the decorative sheet 20. The first surface 20a may be referred to as a bonding surface 20s of the decorative sheet 20.

[0040] 2, in the decorative sheet 20 joined to the display device 10 from the first surface 20a, the second surface 20b is farther from the display device 10 in the first direction D1 than the first surface 20a. The second surface 20b is located on the viewer side of the display system 1.

[0041] 2 and 5, the decorative sheet 20 includes a decorative layer 30 and a bonding layer 40 superposed on the decorative layer 30 in the first direction D1. The decorative sheet 20 includes the bonding layer 40 and the decorative layer 30, in this order, from the first surface 20a to the second surface 20b. The bonding layer 40 forms the first surface 20a (bonding surface 20s) of the decorative sheet 20.

[0042] 2 and 5 has a first surface 30a and a second surface 30b opposite the first surface 30a. The first surface 30a of the decorative layer 30 faces the bonding layer 40. The second surface 30b of the decorative layer 30 constitutes the second surface 20b of the decorative sheet 20.

[0043] A sheet-like separator 23 is overlaid on the decorative sheet 20 shown in Fig. 5. The separator 23 is overlaid on the first surface 20a of the decorative sheet 20. The separator 23 prevents the decorative sheet 20 from being unintentionally bonded to another member. Fig. 5 shows a decorative sheet combination 24 formed by the decorative sheet 20 and the separator 23. The separator 23 is peeled off from the decorative sheet combination 24 when the decorative sheet 20 is bonded to the adherend AB.

[0044] The separator 23 may include a substrate and a release layer overlaid on the substrate. The separator 23 may contact the bonding layer 40 of the decorative sheet 20 through the release layer. The substrate of the separator 23 may include a resin such as polyethylene terephthalate (PET). The release layer may include a silicone resin.

[0045] From the viewpoint of stably holding the decorative sheet 20 on the adherend AB, a lower limit may be set for the peel strength of the decorative sheet 20 on the first surface 20a. The peel strength of the decorative sheet 20 on the first surface 20a may be 10.0 N / 25 mm or more, 15.0 N / 25 mm or more, 17.0 N / 25 mm or more, or 20.0 N / 25 mm or more.

[0046] To allow the decorative sheet 20 to be easily reattached to the adherend AB, the peel strength of the decorative sheet 20 on the first surface 20a may be 40.0 N / 25 mm or less, 35.0 N / 25 mm or less, or 30.0 N / 25 mm or less.

[0047] The peel strength of the decorative sheet 20 on the first surface 20a is measured as follows. First, a decorative sheet sample measuring 200 mm in the machine direction (MD) and 25 mm in the transverse direction (TD) is prepared. If a separator is placed on the sample, the separator is removed. The sample is attached to a 2 mm-thick, 150 mm-wide soda-lime glass plate (silicon dioxide: 70-74%, alumina: 0-2%, calcium oxide: 6-12%, magnesium oxide: 0-4%, sodium oxide: 12-16%) from the first surface. The soda-lime glass was washed with acetone, dried in an 80°C oven (the same oven used for the durability test) for 30 minutes, and then slowly cooled. The sample was pressed by rolling a 2 kg rubber roller back and forth once. The sample was attached with approximately 20 mm of the sample protruding from the glass plate to be clamped by the chuck described below. The portion of the sample attached to the glass plate had a length of about 130 mm in the longitudinal direction. The portion of the sample attached to the glass plate included one end of the sample in the longitudinal direction. The glass plate also included a portion to which the sample was not attached.

[0048] Next, a 180-degree peel strength test is performed using a tensile tester in an environment of 23±1°C and 45-55% RH as follows. The tensile tester includes two chucks spaced apart from each other. The portion of the glass plate to which the decorative sheet is not attached is clamped by one chuck. The portion of the sample not attached to the glass plate is folded back 180 degrees from the portion of the sample attached to the glass plate. A 24 mm wide cellophane tape (CT405AP-24, manufactured by Nichiban Co., Ltd.) is attached to the folded portion of the sample, and this cellophane tape is clamped by the other chuck. The sample in this state is pulled at a pulling rate of 300 mm / min, and the stress is measured. The stress value measurement begins after the sample has been peeled 25 mm from the glass plate. The stress value is measured from the start of the measurement until the sample has been peeled 50 mm from the glass plate. The average of the measured stress values ​​is calculated as a single measurement value. The 180-degree peel strength test is performed on five different samples to obtain five measured values.

[0049] The peel strength of the decorative sheet 20 on the first surface 20a is determined as the average of three of the five measured values, excluding the largest and smallest measured values. The peel strength of the decorative sheet 20 on the first surface 20a is measured in accordance with JIS Z 0237:2009 under conditions other than those mentioned above.

[0050] 1 and 2, the decorative sheet 20 is planar. The planar decorative sheet 20 has a longitudinal direction in the second direction D2. The decorative sheet 20 has a width direction in the third direction D3. Unlike the illustrated example, the decorative sheet 20 may be curved. The curved decorative sheet 20 may be curved around an axis that is not parallel to the first direction D1.

[0051] The decorative sheet 20 displays a design. The design displayed by the decorative sheet 20 may impart a design to the display system 1. The design displayed by the decorative sheet 20 may conceal the display device 10 in a non-display state, as shown in FIG. 3. From the viewpoint of appropriately displaying the design and effectively concealing the display device 10 in a non-display state, an upper limit may be set for the total light transmittance of the decorative sheet 20. The total light transmittance of the decorative sheet 20 may be 70% or less, 50% or less, or 30% or less. From the same viewpoint, a lower limit may be set for the thickness of the decorative sheet 20. The thickness of the decorative sheet 20, i.e., the length in the first direction D1, may be 50 μm or more, or 75 μm or more.

[0052] The total light transmittance of the decorative sheet 20 and certain components of the decorative sheet 20 is measured using a haze meter (HM-150) manufactured by Murakami Color Research Laboratory Co., Ltd., in accordance with the measurement method specified in JIS K 7375:2008.

[0053] The decorative sheet 20 can transmit light emitted from the display device 10 in a display state. The light emitted from the display device 10 passes through the decorative sheet 20 to display an image, as shown in FIG. 4. To enable a clear image to be observed, a lower limit may be set for the total light transmittance of the decorative sheet 20. The total light transmittance of the decorative sheet 20 may be 5.0% or more, or 10% or more. From the same perspective, an upper limit may be set for the thickness of the decorative sheet 20. The thickness of the decorative sheet 20, i.e., the length in the first direction D1, may be 2.0 mm or less, or 1.0 mm or less.

[0054] 2 and 5, the initial value of the yellowness index (YI value) of the decorative sheet 20 is 10.0 or less. The initial value of the yellowness index of the decorative sheet 20 may be 6.00 or less, or 5.40 or less. In the illustrated example, the yellowness index (delta YI) of the decorative sheet 20 is 3.50 or less. The yellowness index of the decorative sheet 20 may be 2.50 or less, 2.20 or less, 2.00 or less, or 1.70 or less. By setting an upper limit for the initial value of the yellowness index and the yellowness index of the decorative sheet 20, the image quality of the image displayed on the display system 1 can be improved, as will be described later.

[0055] The "initial yellowness value" of the decorative sheet 20 and the "initial yellowness value" of the bonding layer 40 each refer to the yellowness measured before the heat resistance test. The heat resistance test is performed by placing the object to be measured for yellowness in a constant temperature dryer DRN420DE (manufactured by Advantec Toyo Co., Ltd.) set at 110°C for 1,000 hours. The "yellowing degree" of the decorative sheet 20 and the "yellowing degree" of the bonding layer 40 refer to the difference between the yellowness measured after the above-mentioned heat resistance test and the initial yellowness value.

[0056] While typical heat resistance tests are conducted at temperatures of around 80°C, the heat resistance test described above is conducted at a temperature of 110°C. Typically, the transmittance of a decorative sheet that displays a design is lower than that of a highly transparent optical film. The amount of heat generated by a decorative sheet when used in combination with a display is greater than that of an optical film when used in combination with a display, because the decorative sheet absorbs light from the display. In particular, in decorative sheets used in combination with a display, the bonding layer that comes into contact with the display requires higher heat resistance than the bonding layer of a typical optical film. For these reasons, the heat resistance test for measuring "yellowing index" is conducted at a higher temperature (110°C) than that of a typical heat resistance test.

[0057] As will be described below, the yellowness of the decorative sheet 20 is determined from the tristimulus values ​​X, Y, and Z in the XYZ color system of the decorative sheet transmitted light that has passed through the decorative sheet 20. The yellowness of the bonding layer 40 is determined from the tristimulus values ​​X, Y, and Z in the XYZ color system of the bonding layer transmitted light that has passed through the bonding layer 40.

[0058] The tristimulus values ​​X, Y, Z in the XYZ color system of light transmitted through the decorative sheet are determined from the spectrum of the light transmitted through the decorative sheet, the spectrum of the light source, and color matching functions. The tristimulus values ​​X, Y, Z in the XYZ color system of light transmitted through the bonding layer are determined from the spectrum of the light transmitted through the bonding layer, the spectrum of the light source, and color matching functions. A D65 light source is used as the light source. The method for determining the tristimulus values ​​X, Y, Z from the spectrum of the light transmitted through the decorative sheet or the bonding layer, the spectrum of the light source, and color matching functions is based on the provisions of JIS Z 8781-3:2016.

[0059] A spectrophotometer (JASCO Corporation's "V-670," compliant with JIS K 0115:2020) is used to measure the spectrum of light transmitted through the decorative sheet and the bonding layer. The spectrum of light transmitted through the decorative sheet and the bonding layer is measured at a wavelength of 300 nm to 800 nm, a bandwidth of 5.0 nm, a scanning speed of 1000 nm / min, a data acquisition interval of 1.0 nm, and a field of view of 2°. The tristimulus values ​​X, Y, and Z calculated from the spectrum of light transmitted through the decorative sheet or the bonding layer, the spectrum of the light source, and the color matching function are measured at a data interval of 5.0 nm.

[0060] The yellowness is determined according to the following formula using the tristimulus values ​​X, Y, and Z determined by the above-mentioned method, based on the provisions of JIS K 7373:2006. YI=100(1.2985X-1.1335Z) / Y The geometrical optical condition for measuring the yellowness index is the geometrical optical condition e of JIS Z 8722:2009. Before measuring the yellowness index, the D65 light source is turned on for 15 minutes or more to stabilize the output. The incident surface for measuring the yellowness index of the decorative sheet 20 is the first surface 20a. The test environment for measuring the yellowness index is a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5%. The sample is placed in the test environment for 16 hours before starting the test.

[0061] The yellowness index is the arithmetic mean of five measurements. The five measurements are taken at five different measurement positions on the object to be measured. The five measurement positions are located at least 5 mm apart from each other. Other measurement conditions for measuring yellowness index are in accordance with JIS K 7373:2006.

[0062] The initial value of the yellowness of the decorative sheet 20 may be −5.0 or more, or −2.0 or more. By setting a lower limit for the initial value of the yellowness of the decorative sheet 20, it is possible to prevent the image light transmitted through the decorative sheet 20 from appearing bluish.

[0063] There is no particular lower limit set for the yellowing degree of the decorative sheet 20. The yellowing degree of the decorative sheet 20 may be −2.0 or more, or −1.0 or more.

[0064] 2 and 5, the decorative layer 30 includes a base material layer 31 and a design layer 32. The design layer 32 is located between the base material layer 31 and the bonding layer 40 in the first direction D1. Note that the base material layer 31 of the decorative layer 30 is omitted in FIG. 6.

[0065] The base material layer 31 supports the layers of the decorative layer 30 other than the design layer 32. The base material layer 31 may support the bonding layer 40 bonded to the decorative layer 30. The base material layer 31 may be a film. The base material layer 31 may be transparent. The base material layer 31 may be colored. The base material layer 31 may contain a resin as a material. The resin contained in the base material layer 31 may be one or more of polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, triacetyl cellulose, polystyrene, cyclic polyolefin, and ABS (acrylonitrile butadiene styrene copolymer).

[0066] "Transparent" means that the total light transmittance is 50% or more. When a certain component of the decorative sheet 20 is transparent, the total light transmittance of that component may be 80% or more, or even 90% or more. The total light transmittance is measured by the method described above.

[0067] The design layer 32 imparts design to the decorative layer 30 and the decorative sheet 20. The design layer 32 may express a design that displays a background. The design layer 32 may display a picture or a geometric pattern. The picture may be a wood grain or marble pattern. The design layer 32 may display one or more of the following designs as a design: a figure, a pattern, a design, a color, a picture, a photograph, a character, a mark, a pictogram, letters, numbers, etc.

[0068] The design layer 32 may include a binder resin portion and a color material held by the binder resin portion. The binder resin portion may include a thermoplastic resin. The color material may be a dye, a pigment, or a combination of a dye and a pigment.

[0069] The decorative layer 30 may include other layers in addition to the base layer 31 and the design layer 32. The illustrated decorative layer 30 includes a light-blocking layer 33 having light-blocking properties. The light-blocking layer 33 is superimposed on the design layer 32 from the second side in the first direction D1. The design layer 32 is located between the base layer 31 and the light-blocking layer 33 in the first direction D1. The light-blocking layer 33 is located between the design layer 32 and the bonding layer 40 in the first direction D1.

[0070] The light-shielding layer 33 having "light-shielding properties" means that the light-shielding layer 33 has a total light transmittance of 1% or less. A light-shielding layer 33 having light-shielding properties may have a total light transmittance of 0.2% or less. The total light transmittance of the light-shielding layer 33 is measured by the method described above.

[0071] The light-shielding layer 33 absorbs light emitted from the display device 10 in a displaying state. By absorbing light from the display device 10, the design formed by the design layer 32 can be clearly displayed. The light-shielding layer 33 may include a binder resin portion and light-absorbing particles held by the binder resin portion. The light-absorbing particles may include a black pigment such as carbon black or titanium black.

[0072] The decorative layer 30 having the above configuration has an uneven surface 35 on the first surface 30a. The uneven surface 35 includes a portion facing the first direction D1. The uneven surface 35 includes a plurality of recesses 36 that open toward the bonding layer 40. The uneven surface 35 includes a plurality of protrusions 37 that protrude toward the bonding layer 40.

[0073] 2 and 5, the uneven surface 35 includes recesses 36 and protrusions 37 arranged alternately in the second direction D2. In the illustrated example, the protrusions 37 are formed by the design layer 32 and the light-blocking layer 33. The decorative layer 30 does not include the design layer 32 or the light-blocking layer 33 at the recesses 36. The decorative layer 30 may transmit light emitted from the display device 10 at the recesses 36. The recesses 36 may be referred to as transmissive portions.

[0074] The height difference t1 of the uneven surface 35 in the first direction D1 may be 1.0 μm or more, 3.0 μm or more, or 5.0 μm or more. The height difference t1 of the uneven surface 35 in the first direction D1 may be 30 μm or less, or 20 μm or less.

[0075] The height difference t1 of the uneven surface 35 in the first direction D1 is determined as follows: The uneven surface 35, which includes at least one recess 36 and a protrusion 37 adjacent to the recess 36, is observed from a direction perpendicular to the first direction D1. In the observation field, a first location of the first surface 30a that is the deepest recess, and the recess 36 that constitutes the first location, are identified. In the protrusion 37 adjacent to the identified recess 36, a second location that is the farthest from the first location in the first direction D1 is identified. The distance between the first location and the second location in the first direction D1 is measured as the height difference of the uneven surface 35 in one field. The height difference t1 of the uneven surface 35 in the first direction D1 is determined as the average of the above-mentioned measured values ​​measured in five different fields. An optical microscope (Keyence Corporation Digital Microscope VHX-6000) is used to observe the uneven surface 35.

[0076] 5, the recess 36 includes a bottom 361, an opening 362 facing the first direction D1, and a side 363 connecting the bottom 361 and the opening 362. The bottom 361 is formed by the base material layer 31. The side 363 is formed by the design layer 32 and the light-shielding layer 33.

[0077] 6, the recesses 36 may be two-dimensionally arranged in a direction non-parallel to the first direction D1. In the illustrated example, the recesses 36 are regularly spaced apart in the second direction D2 and the third direction D3. In particular, the recesses 36 are arranged in a lattice pattern. That is, the recesses 36 are arranged at a constant pitch in the second direction D2 and at a constant pitch in the third direction D3.

[0078] 6, the recesses 36 have a circular shape in plan view. However, the recesses 36 are not limited to the illustrated example, and may have various shapes such as a square shape or a pentagon shape in plan view.

[0079] 6, the recesses 36 may extend linearly on the uneven surface 35. The protrusions 37 may also extend linearly. On the uneven surface 35, the linearly extending recesses 36 and the linearly extending protrusions 37 may be arranged alternately. On the uneven surface 35, a plurality of linearly extending recesses 36 may intersect with each other.

[0080] The recess 36 may have a shape tapered toward the bottom 361, as shown in FIG. 5 . The recess 36 may have a shape tapered toward the first side in the first direction D1, i.e., toward the second surface 20b. In the tapered recess 36, the cross-sectional area of ​​the recess 36 taken along a plane perpendicular to the first direction D1 is smaller at the bottom 361 than at the opening 362, as shown in FIG. 6 . In the illustrated example, the cross-sectional area of ​​the recess 36 taken along a plane perpendicular to the first direction D1 gradually decreases from the opening 362 toward the bottom 361. In the tapered recess 36, the side portion 363 may extend in a direction inclined with respect to the first direction D1, as shown in FIG. 5 .

[0081] In the examples shown in Figures 2 and 5, the bonding layer 40 is superimposed on the decorative layer 30 in the first direction D1. The bonding layer 40 superimposed on the decorative layer 30 has a certain thickness. In other words, the bonding layer 40 superimposed on the decorative layer 30 has a certain length in the first direction D1, which is the stacking direction. The bonding layer 40 is bonded to the decorative layer 30. The bonding layer 40 forms the first surface 20a of the decorative sheet 20. The bonding layer 40 does not form the surface of the decorative sheet 20 that faces the viewer. In Figure 2, the decorative sheet 20 is bonded to the display device 10 via the bonding layer 40.

[0082] The bonding layer 40 suppresses relative movement of adjacent members in the first direction D1 via the bonding layer 40. In the example shown in Fig. 2, the bonding layer 40 is located between the decorative layer 30 and the display device 10. The decorative sheet 20 is bonded to the display device 10 via the bonding layer 40, thereby suppressing relative movement of the decorative layer 30 and the display device 10.

[0083] 2 and 5, the bonding layer 40 is bonded to the first surface 30a of the decorative layer 30. The bonding layer 40 is bonded to the uneven surface 35 of the decorative layer 30. The bonding layer 40 is overlaid on the decorative layer 30 so as to fill the multiple recesses 36.

[0084] The bonding layer 40 may contain a thermoplastic resin. The thermoplastic resin contained in the bonding layer 40 may include one or more of acrylic, PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PEI (polyetherimide), PVAL (polyvinyl alcohol), PVCD (polyvinylidene chloride), nylon 6, nylon 66, silicone, polyurethane, styrene rubber, and butadiene rubber. In particular, the thermoplastic resin contained in the bonding layer 40 is preferably acrylic or silicone from the viewpoint of ensuring relatively high heat resistance.

[0085] The bonding layer 40 may include a cured resin. The cured resin may include a cured ionizing radiation curable compound and a photopolymerization initiator. The ionizing radiation curable compound may include one or more of an ultraviolet curable compound and an electron beam curable compound. The ultraviolet curable compound is a resin that is cured by irradiation with ultraviolet rays. The electron beam curable compound is a resin that is cured by irradiation with electron beams. In the bonding layer 40, one type of ionizing radiation curable compound may be used alone, or two or more types of ionizing radiation curable compounds may be used in combination.

[0086] The ionizing radiation-curable compound contains an ionizing radiation-curable functional group. The ionizing radiation-curable functional group is a group that cures upon irradiation with ionizing radiation. Examples of the ionizing radiation-curable functional group include functional groups having an ethylenic double bond, such as a (meth)acryloyl group, a vinyl group, and an allyl group. Examples of the ionizing radiation-curable functional group include an epoxy group and an oxetanyl group. The ionizing radiation-curable compound may contain two or more ionizing radiation-curable functional groups. The ionizing radiation-curable compound may be a compound having an ethylenically unsaturated bond group. The ionizing radiation-curable compound may be a (meth)acrylate compound having a (meth)acryloyl group. The ionizing radiation-curable compound may be a siloxane compound containing a siloxane bond.

[0087] The term "ionizing radiation" refers to electromagnetic waves or charged particle beams that have an energy quantum capable of polymerizing or crosslinking molecules. Ionizing radiation may be ultraviolet (UV) rays or electron beams (EB). Ionizing radiation may be electromagnetic waves such as X-rays and gamma rays, or charged particle beams such as alpha rays and ion beams.

[0088] The photopolymerization initiator initiates curing of the ultraviolet-curable compound and may be one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzil dimethyl ketal, benzoyl benzoate, α-acyloxime ester, thioxanthones, etc.

[0089] The cured resin may contain a cured thermosetting compound. A thermosetting compound is a resin that hardens when heated. Examples of the thermosetting compound include phenolic resins, urea resins, diallyl phthalate resins, melamine resins, guanamine resins, unsaturated polyester resins, polyurethane resins, epoxy resins, aminoalkyd resins, melamine-urea co-condensation resins, and silicone resins. The curable resin composition may contain one or more of these thermosetting compounds.

[0090] The above description regarding the cured resin also applies to the case where the resin contained in the bonding portion 15 includes a cured resin, as will be described later with reference to FIG.

[0091] The bonding layer 40 is formed from an adhesive. The adhesive may be in a sheet form at room temperature. An adhesive in a sheet form at room temperature may be called an adhesive sheet. Separators may be laminated on both sides of the adhesive sheet.

[0092] The adhesive may include a thermoplastic resin. The adhesive may include an acrylic or a silicone as the thermoplastic resin. The adhesive may include an ionizing radiation curable compound. The adhesive may include a thermosetting compound.

[0093] 2 and 5 is formed from an adhesive in contact with the decorative layer 30. When the bonding layer 40 is formed, the adhesive may contact the textured surface 35 of the decorative layer 30. The adhesive may bond to the textured surface 35 of the decorative layer 30.

[0094] When forming the bonding layer 40, the adhesive sheet may be pressure-bonded to the uneven surface 35 of the decorative layer 30. In other words, the bonding layer 40 may be formed by applying pressure to an adhesive in contact with the uneven surface 35 of the decorative layer 30. When the bonding layer 40 is formed from an adhesive sheet pressure-bonded to the uneven surface 35 of the decorative layer 30, the bonding layer 40 may be peelable from the uneven surface 35 of the decorative layer 30. The bonding layer 40 may be formed by curing the adhesive in contact with the uneven surface 35 of the decorative layer 30. The bonding layer 40 may be formed by drying the adhesive in contact with the uneven surface 35 of the decorative layer 30. The bonding layer 40 may be formed by cooling the adhesive in contact with the uneven surface 35 of the decorative layer 30.

[0095] 2 and 5 can transmit light emitted from the display device 10. The bonding layer 40 may be transparent in order to display a clear image using light from the display device 10. The total light transmittance of the bonding layer 40 may be 80% or more, 90% or more, 95% or more, or 99% or more.

[0096] From the viewpoint of displaying a clear image using light from the display device 10, an upper limit may be set for the transmission haze of the bonding layer 40. The transmission haze of the bonding layer 40 may be 2.0% or less, 1.0% or less, 0.70% or less, 0.50% or less, or 0.30% or less.

[0097] The transmission haze of the bonding layer 40 is measured using a haze meter (HM-150) manufactured by Murakami Color Research Laboratory Co., Ltd. To stabilize the output of the light source of the haze meter, the light source is turned on for 15 minutes or more prior to measuring the transmission haze. When measuring the transmission haze, the angle of incidence of the light source light on the measurement target is set to 0°. The test environment for measuring the transmission haze is a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5%. Other measurement conditions for measuring the transmission haze are in accordance with JIS K7136:2000.

[0098] The transmission haze value of the bonding layer 40 may be set from a viewpoint different from that described above. In order to provide the bonding layer 40 with light diffusibility, the transmission haze of the bonding layer 40 may be a value greater than the above-described numerical range. The transmission haze of the bonding layer 40 may be 30% or more and 90% or less. When the bonding layer 40 has light diffusibility, moire patterns that occur due to interference between the pixel pitch of the display device 10 and the pitch of the openings (recesses 36) in the decorative layer 30 of the decorative sheet 20 can be reduced.

[0099] To impart light diffusing properties to the bonding layer 40, a light diffusing material may be blended into the bonding layer 40. Examples of the light diffusing material 62 include inorganic particles such as barium sulfate particles, glass particles, aluminum hydroxide particles, calcium carbonate particles, silica (silicon dioxide) particles, and titanium oxide particles, and organic particles such as melamine beads, acrylic beads, acrylic-styrene beads, polycarbonate beads, polyethylene beads, polystyrene beads, PVC beads, and silicone beads. The particle size of the light diffusing material may be 2.0 μm or more and 20 μm or less.

[0100] From the viewpoint of stably bonding the decorative sheet 20 to the adherend AB, a lower limit may be set for the storage modulus G' of the bonding layer 40 at room temperature. The storage modulus G' of the bonding layer 40 at 25°C may be 20 kPa or more, or 50 kPa or more.

[0101] From the viewpoint of stably bonding the bonding layer 40 to the uneven surface 35, an upper limit may be set for the storage modulus G' of the bonding layer 40 at room temperature. The storage modulus G' of the bonding layer 40 at 25°C may be 1.0 MPa or less, or 0.50 MPa or less. By setting an upper limit for the storage modulus G' of the bonding layer 40 at room temperature, the bonding layer 40 can easily follow the shape of the uneven surface 35. This increases the area of ​​contact between the uneven surface 35 and the bonding layer 40, allowing the bonding layer 40 to be stably bonded to the uneven surface 35.

[0102] Furthermore, an upper limit may be set for the storage modulus G' of the bonding layer 40 at 80°C. The storage modulus G' of the bonding layer 40 at 80°C may be 1.0 MPa or less, or 0.50 MPa or less. By setting an upper limit for the storage modulus G' of the bonding layer 40 at 80°C, the bonding layer 40 can easily conform to the shape of the uneven surface 35 when heated. This increases the area of ​​contact between the uneven surface 35 and the bonding layer 40 when the bonding layer 40 is heated, allowing the bonding layer 40 to be stably bonded to the uneven surface 35. Furthermore, by cooling in a state where the area of ​​contact between the uneven surface 35 and the bonding layer 40 has increased, the elastic modulus at room temperature can be improved, and the bonded state can be maintained more stably.

[0103] The storage modulus G' is determined as follows by the torsion pendulum method specified in JIS K 7244-2:1999. First, a test piece having a length of 70 mm and a width of 10 mm is prepared as a sample to be measured. Next, the test piece is attached to the testing equipment so that the distance between the clamps is 50 mm. In this state, the test piece is twisted from one end in the longitudinal direction at a frequency of 1 Hz under temperature conditions of -20°C to 90°C at a temperature rise rate of 5°C / min, and the vibration waveform is measured. The storage modulus G' is calculated from the frequency and damping amplitude of the measured vibration waveform. The storage modulus G' is measured in accordance with JIS K 7244-2:1999 under conditions other than those mentioned above.

[0104] In the examples shown in FIGS. 2 and 5 , the initial yellowness value of the bonding layer 40 is 2.00 or less. The initial yellowness value of the bonding layer 40 may be 1.50 or less. In the illustrated examples, the yellowness index of the bonding layer 40 is 3.50 or less. The yellowness index of the bonding layer 40 may be 2.00 or less, 1.00 or less, 0.50 or less, 0.15 or less, or 0.10 or less. By setting an upper limit for the initial yellowness value and the yellowness index of the bonding layer 40, the quality of the image displayed in the display system 1 can be improved, as described below. The initial yellowness value and the yellowness index of the bonding layer 40 are determined by the method described above.

[0105] From the viewpoint of stably bonding the decorative sheet 20 to the adherend AB, the maximum thickness t2 of the bonding layer 40, i.e., the maximum length t2 of the bonding layer 40 in the first direction D1, may be 25.0 μm or more, 30.0 μm or more, or 50.0 μm or more. From the same viewpoint, the maximum thickness t2 of the bonding layer 40 may be greater than the maximum thickness t3 of the base layer 31, i.e., the maximum length t3 of the base layer 31 in the first direction D1, as shown in FIG. 5. The maximum thickness t2 of the bonding layer 40 may be 100 μm or less, or 80.0 μm or less.

[0106] The maximum thickness t2 of the bonding layer 40 is measured using a digital micrometer "MFC-101" and a digital microstand "MS-11C" when the bonding layer 40 can be peeled off from the decorative sheet 20. Both the digital micrometer and the digital microstand are manufactured by Nikon Corporation. When measuring the maximum thickness t2 of the bonding layer 40, the digital micrometer is attached to the digital microstand. When measuring the thickness, the bonding layer 40 is sandwiched between the stage of the digital microstand and the shaft of the digital micrometer. In this state, the digital micrometer's reading is read to obtain the measurement value. The maximum thickness t2 of the bonding layer 40 is determined as the maximum of the measurements taken at five different locations.

[0107] The maximum thickness t3 of the base layer 31 is determined as follows. Furthermore, when the bonding layer 40 cannot be peeled off from the decorative sheet 20, the maximum thickness t2 of the bonding layer 40 is also determined as follows. A cross section of the decorative sheet 20 including the component to be measured is observed from a direction perpendicular to the first direction D1. In the observation field, the point where the thickness of the measurement object is greatest is identified, and the thickness of the measurement object at that point is measured. The "maximum thickness" of the component of the decorative sheet 20 is determined as the maximum of five measured values ​​for the thickness of the component measured in five different fields of view. An optical microscope (Keyence Corporation Digital Microscope VHX-6000) is used to observe the cross section of the decorative sheet 20.

[0108] 2 and 5, the maximum thickness t2 of the bonding layer 40 is greater than the height difference t1 of the uneven surface 35. The maximum thickness t2 of the bonding layer 40 is 2.0 times or more the height difference t1 of the uneven surface 35. The maximum thickness t2 of the bonding layer 40 may be 3.0 times or more, or may be 5.0 times or more the height difference t1 of the uneven surface 35. By setting a lower limit value for the ratio of the maximum thickness t2 of the bonding layer 40 to the height difference t1 of the uneven surface 35, the quality of the image displayed in the display system 1 can be improved, as will be described later.

[0109] From the viewpoint of reducing the thickness of the bonding layer 40, an upper limit may be set for the ratio of the maximum thickness t2 of the bonding layer 40 to the height difference t1 of the uneven surface 35. The maximum thickness t2 of the bonding layer 40 may be 200 times or less, 100 times or less, or 50 times or less the height difference t1 of the uneven surface 35. By reducing the thickness of the bonding layer 40, the manufacturing cost of the decorative sheet 20 can be reduced, and since the bonding layer may yellow at high temperatures, making the bonding layer thinner can reduce the effect of yellowing.

[0110] Next, an example of a method for manufacturing the illustrated decorative sheet 20 will be described mainly with reference to FIG.

[0111] The decorative layer 30 is prepared. A base film 31A that will form the base layer 31 is prepared. The base film 31A may be a film material containing the resin described above as the material for the base layer 31. As shown in FIG. 7, a design film 32A that will form the design layer 32 is applied to the base film 31A. The design film 32A may be printed on the base film 31A. The design film 32A may be printed on the base film 31A by various methods such as gravure printing.

[0112] As shown in FIG. 7, a light-shielding film 33A that forms the light-shielding layer 33 may be formed on a design film 32A. The light-shielding film 33A may contain a resin composition. This resin composition may contain the binder resin and light-absorbing particles described above as materials contained in the light-shielding layer 33. By forming the light-shielding film 33A on the design film 32A, a laminate 60 is obtained that contains, in this order, the base film 31A, the design film 32A, and the light-shielding film 33A. The laminate 60 contains, in this order from the first surface 60a to the second surface 60b, the light-shielding film 33A, the design film 32A, and the base film 31A. The laminate 60 does not necessarily have to contain the light-shielding film 33A.

[0113] Next, a portion of the laminate 60 is removed to create a decorative layer 30 having an uneven surface 35 on the first surface 30a. In the example shown in FIG. 7, a portion of the laminate 60 is removed by laser etching from the second surface 60b side. A portion of the light-shielding film 33A and a portion of the decorative film 32A are removed by laser light L incident on the laminate 60 from the second surface 60b side. By removing a portion of the light-shielding film 33A and a portion of the decorative film 32A, an opening is formed on the first surface 60a of the laminate 60. This opening forms a recess 36.

[0114] The laser light used for laser etching is not particularly limited. Laser light emitted from various types of laser light sources can be used. The wavelength of the laser light used for laser etching is also not particularly limited. The laser light may have a wavelength in the visible light range or in the infrared range. Laser light that has a high absorption rate in the light-shielding film 33A may be used.

[0115] In this manner, a decorative layer 30 including a plurality of recesses 36, i.e., a decorative layer 30 having an uneven surface 35, is obtained. The method of forming the plurality of recesses 36 is not limited to the laser etching described above. The openings may be formed on the first surface 60a of the laminate 60 by scribing the first surface 60a. The openings may be formed on the first surface 60a of the laminate 60 by blasting the first surface 60a. Alternatively, the openings may be formed using photolithography.

[0116] Next, the bonding layer 40 is formed on the decorative layer 30. When forming the bonding layer 40, an adhesive is brought into contact with the uneven surface 35 of the decorative layer 30. As an example, when forming the bonding layer 40, the above-mentioned adhesive sheet is brought into contact with the uneven surface 35 of the decorative layer 30. In this example, the bonding layer 40 may be formed by pressing the adhesive sheet and the decorative layer 30 together. In other words, the bonding layer 40 may be formed by applying pressure to the adhesive sheet in contact with the uneven surface 35 of the decorative layer 30. Pressure may be applied to the adhesive sheet by a rubber roller. A separator may be placed between the rubber roller and the adhesive sheet.

[0117] The method for forming the bonding layer 40 on the decorative layer 30 is not limited to the above-mentioned method. For example, when the adhesive contains a thermoplastic resin, the bonding layer 40 may be formed by cooling the adhesive in contact with the decorative layer 30. For example, when the adhesive contains an ionizing radiation curable compound or a thermosetting compound, the bonding layer 40 may be formed by curing the adhesive in contact with the decorative layer 30.

[0118] In this manner, a decorative sheet 20 is obtained, which includes the decorative layer 30 and the bonding layer 40 superimposed on the decorative layer 30. In the obtained decorative sheet 20, the first surface 20a is formed by the bonding layer 40. The second surface 20b is formed by the decorative layer 30 (base layer 31).

[0119] The resulting decorative sheet 20 is attached to an adherend AB from the first surface 20a formed by the bonding layer 40. When the adherend AB is a display device 10, the display system 1 shown in Fig. 2 is produced by attaching the decorative sheet 20 to the display surface 11 of the display device 10 from the first surface 20a. A separator 23 may be superimposed on the first surface 20a of the decorative sheet 20 after the decorative sheet 20 is produced and before it is attached to the adherend AB.

[0120] The operation of the illustrated display system 1 will now be described.

[0121] When the display device 10 is in a non-display state, emission of image light from the display surface 11 is stopped. In this state, as shown in FIG. 3, the decorative sheet 20 superimposed on the display surface 11 of the display device 10 is observed. A viewer of the display system 1 observes the design of the decorative sheet 20 formed by the design layer 32. In other words, when the display device 10 is in a non-display state, the display device 10 and the display surface 11 of the display device 10 are concealed by the decorative sheet 20. In the display system 1, the display surface 11, which is observed as black in the non-display state, can be concealed by the decorative sheet 20. This allows the display device 10 to be installed while ensuring harmony and uniformity with the surrounding environment.

[0122] When the display device 10 is in a display state, image light is emitted from the display surface 11 toward the decorative sheet 20. The image light enters the decorative sheet 20 from the first surface 20a. The light that enters the decorative sheet 20 passes through the bonding layer 40 and travels toward the decorative layer 30. The light that travels toward the decorative layer 30 reaches one of the base layer 31, the design layer 32, and the light-shielding layer 33. The light that reaches the light-shielding layer 33 is absorbed by light-absorbing particles contained in the light-shielding layer 33. The light that reaches the design layer 32 passes through the design layer 32 and travels toward the base layer 31. The light that reaches the base layer 31 passes through the base layer 31 and is emitted from the second surface 20b of the decorative sheet 20. The display system 1 displays an image using the light emitted from the second surface 20b, as shown in FIG. 4. In the illustrated example, the character string "ABC" is displayed as an image.

[0123] In a conventional display system including a display device that emits image light from its display surface and a decorative sheet bonded to the display surface of the display device, the display device generates heat due to the emission of light. In particular, the display device generates heat at its display surface. The heated display device heats the decorative sheet bonded to the display surface. When the decorative sheet is heated over a long period of time, components of the decorative sheet may turn yellow. This yellowing of the components of the decorative sheet may cause a problem in that the image light emitted from the display surface and transmitted through the decorative sheet turns yellow over time.

[0124] In response to this, the present inventors have found that upper limits can be set for the initial value of yellowness and the yellowing index of the decorative sheet 20. The initial value of yellowness of the decorative sheet 20 is 10.0 or less. The yellowing index of the decorative sheet 20 is 3.50 or less. According to this specific example, as will be shown in the examples described later, it is possible to prevent an image formed by light transmitted through the decorative sheet 20 from turning yellow over time. This improves the image quality of the image displayed in the display system 1.

[0125] The yellowing degree of the decorative sheet is most susceptible to the influence of the bonding layer that comes into contact with the display surface of the heated display device. From this point of view, the present inventors have found that the initial value of yellowing degree of the bonding layer and the upper limit of yellowing degree should be set. The initial value of yellowing degree of the bonding layer 40 is 2.00 or less. The yellowing degree of the bonding layer 40 is 3.50 or less. This specific example also suppresses discoloration of light transmitted through the decorative sheet 20.

[0126] Furthermore, in a conventional display system, dot-like shadows were observed in an image displayed by the display device through a decorative sheet. This display system included a display device and a decorative sheet attached to the display device. The decorative sheet included a decorative layer having an uneven surface and a bonding layer bonded to the uneven surface. The decorative sheet was attached to the display device via the bonding layer. The inventors of the present invention confirmed that the dot-like shadows were caused by image light passing through air bubbles contained in the display system. The air bubbles were located between the display device and the decorative sheet. Air bubbles were also observed within the decorative sheet. The air bubbles within the decorative sheet were located between the decorative layer and the bonding layer.

[0127] It is assumed that the bubbles are formed by the following mechanism, however, the present disclosure is not bound by the following assumption.

[0128] By bonding the bonding layer to the uneven surface of the decorative layer, the shape of the bonding layer follows the shape of the uneven surface. The bonding layer also has an uneven shape on the surface opposite the uneven surface. The decorative sheet has an uneven shape on the surface formed by the bonding layer. When this decorative sheet is attached to the display device via the bonding layer, air tends to remain in the recesses between adjacent protrusions of the uneven shape. It is estimated that the air remaining in the recesses forms air bubbles between the decorative sheet and the display device.

[0129] In response to this, the present inventors discovered that the incorporation of air bubbles can be suppressed by making the thickness of the bonding layer sufficiently large relative to the height difference of the uneven surface. Specifically, a lower limit was set for the ratio of the height difference of the uneven surface to the thickness of the bonding layer. In the decorative sheet 20 shown in FIGS. 1 to 6, the maximum length of the bonding layer 40 in the first direction D1 is 2.0 times or more the height difference of the uneven surface 35 in the first direction D1. By ensuring that the bonding layer 40 is sufficiently thick relative to the height difference of the uneven surface 35, the first surface 20a, i.e., the surface of the bonding layer 40 opposite to the surface bonded to the uneven surface 35, can be flattened. This suppresses the formation of air bubbles between the display device 10 and the decorative sheet 20.

[0130] In one specific example of the decorative sheet 20 shown in FIG. 5 , the uneven surface 35 includes a plurality of recesses 36 that open toward the bonding layer 40. Each of the plurality of recesses 36 has a shape that tapers toward the bottom 361 of the recess 36. According to this specific example, the cross-sectional area of ​​the recess 36 in a plane perpendicular to the first direction D1 is larger at the opening 362 than at the bottom 361. This makes it possible to prevent the openings of the recesses 36 from being blocked by the composition that forms the bonding layer 40 during production of the decorative sheet 20. Therefore, according to this specific example, it is possible to prevent the formation of air bubbles between the decorative layer 30 and the bonding layer 40 that is overlaid on the uneven surface 35.

[0131] In one specific example of the decorative sheet 20 shown in FIG. 5, the bonding layer 40 contains a cured resin. According to this specific example, when forming the bonding layer 40, a composition containing an uncured resin is applied to the decorative layer 30. In general, the storage modulus G' of a composition containing an uncured resin is significantly lower than the storage modulus G' of a compound containing a cured resin. The composition containing the uncured resin can easily conform to the shape of the uneven surface 35 of the decorative layer 30. This can prevent air bubbles from forming between the decorative layer 30 and the bonding layer 40.

[0132] 5, the first surface 20a formed by the bonding layer 40 is flat. According to this specific example, when the decorative sheet 20 is attached to the adherend AB from the first surface 20a onwards, it is possible to particularly effectively prevent air from remaining between the decorative sheet 20 and the adherend AB. In the illustrated display system 1, by attaching the decorative sheet 20 to the display device 10 from the flat first surface 20a onwards, it is possible to effectively prevent air bubbles from being mixed in between the display device 10 and the decorative sheet 20. Therefore, it is possible to effectively improve the quality of images displayed in the display system 1.

[0133] In the embodiment described above, the decorative sheet 20 includes a decorative layer 30 including a base layer 31 and a design layer 32, and a bonding layer 40 superimposed on the decorative layer 30 in the first direction D1. The design layer 32 is located between the base layer 31 and the bonding layer 40. The total light transmittance of the decorative sheet 20 is 5.0% or more and 70% or less. The initial yellowness index of the bonding layer 40 is 2.00 or less, and the yellowing index of the bonding layer 40 is 3.50 or less.

[0134] In the embodiment described above, the decorative sheet 20 includes a decorative layer 30 including a base layer 31 and a design layer 32, and a bonding layer 40 superimposed on the decorative layer 30 in the first direction D1. The design layer 32 is located between the base layer 31 and the bonding layer 40. The total light transmittance of the decorative sheet 20 is 5.0% or more and 70% or less. The initial yellowness index of the decorative sheet 20 is 10.0 or less, and the yellowing index of the decorative sheet 20 is 3.50 or less.

[0135] The decorative sheet 20 according to these embodiments is prevented from increasing in yellowness even when heated while being placed on the display device 10. In the display system 1 including the decorative sheet 20, the yellowing of light transmitted through the decorative sheet 20 can be prevented even over time. This allows the display system 1 including these decorative sheets 20 to improve the quality of the displayed image.

[0136] Furthermore, in the embodiment described above, the decorative sheet 20 includes a decorative layer 30 including a base layer 31 and a design layer 32, and a bonding layer 40 superimposed on the decorative layer 30 in the first direction D1. The design layer 32 is located between the base layer 31 and the bonding layer 40. The decorative layer 30 has an uneven surface 35. The bonding layer 40 is bonded to the uneven surface 35. The total light transmittance of the decorative sheet 20 is 5.0% or more and 70% or less. The maximum thickness t2 of the bonding layer 40 is 2.0 times or more the height difference of the uneven surface 35 in the first direction D1. According to this embodiment, when the decorative sheet 20 is attached to the adherend AB via the bonding layer 40, it is possible to prevent air bubbles from being generated between the decorative sheet 20 and the adherend AB. When the decorative sheet 20 is attached to the display device 10, i.e., when the adherend AB is the display device 10, it is possible to prevent air bubbles from being generated between the decorative sheet 20 and the display device 10. The display system 1 including such a decorative sheet 20 can improve the quality of the displayed image.

[0137] Although one embodiment has been described with reference to specific examples, the above-described specific examples do not limit the present invention. The above-described embodiment can be implemented with various other specific examples, and various omissions, substitutions, changes, additions, etc. can be made without departing from the spirit of the present invention.

[0138] In the above-described specific example of the decorative sheet 20, the decorative layer 30 includes the light-shielding light-blocking layer 33. However, the decorative layer 30 is not limited to this, and may not include the light-blocking layer 33, as shown in the decorative sheet 20 of FIG.

[0139] In one specific example of the decorative sheet 20 described above, the decorative layer 30 includes an uneven surface 35 on the first surface 30a. The uneven surface 35 includes a plurality of recesses 36. The recesses 36 penetrate the design layer 32. However, this is not limiting, and the recesses 36 do not have to penetrate the design layer 32, as shown in FIG. 8 .

[0140] As shown in Fig. 8, the decorative layer 30 may include multiple printed layers 34. In the illustrated example, the printed layer 34 includes a first printed layer 341 and a second printed layer 342 superimposed on the first printed layer 341. The second printed layer 342 is located between the first printed layer 341 and the bonding layer 40 in the first direction D1. The design layer 32 may be formed by the multiple printed layers 34. As shown in Fig. 8, the decorative layer 30 may include a portion where the second printed layer 342 is not printed.

[0141] 8, a recess 36 may be formed by multiple printed layers 34. In the illustrated example, the recess 36 is formed in a portion where the second printed layer 342 is not printed. A bottom 361 of the recess 36 is formed by the first printed layer 341. A side 363 of the recess 36 is formed by the second printed layer 342.

[0142] In the specific example of the decorative sheet 20 described above, the maximum thickness t2 of the bonding layer 40 is larger than the maximum thickness t3 of the base material layer 31. However, this is not limiting, and as shown in FIG. 8, the maximum thickness t2 of the bonding layer 40 may be smaller than the maximum thickness t3 of the base material layer 31. According to this specific example, the base material layer 31 can support the bonding layer 40 more stably. Furthermore, by reducing the thickness of the bonding layer 40, the manufacturing cost of the decorative sheet 20 can be reduced.

[0143] In one specific example of the display system 1 described above, the decorative sheet 20 is attached to the display device 10. The adherend AB of the decorative sheet 20 is the display device 10. However, the present invention is not limited to this, and the decorative sheet 20 may be attached to a support member 21 as shown in FIG. 9. That is, the adherend AB may be the support member 21. The support member 21 supports the decorative sheet 20. The support member 21 and the decorative sheet 20 attached to the support member 21 may form a decorative member 25. The display system 1 may include a display device 10 and a decorative member 25 attached to the display device 10 as shown in FIG. 9.

[0144] 9, the support member 21 is a plate-shaped member having a first surface 21a and a second surface 21b opposite to the first surface 21a. In the illustrated example, the first surface 20a of the decorative sheet 20 is attached to the first surface 21a of the support member 21. The support member 21 may be transparent. The support member 21 may include glass.

[0145] As shown in Fig. 9, the decorative member 25 may include a surface layer 26. The surface layer 26 forms the surface of the decorative member 25 that faces the viewer. The surface layer 26 is overlaid on the second surface 21b of the support member 21. The surface layer 26 may perform various functions. The surface layer 26 may be an antiglare layer having an antiglare function. The surface layer 26 may be an antireflection layer having an antireflection function.

[0146] In the specific example of the display system 1 described above, the decorative sheet 20 is overlaid on the display device 10 from the first surface 20a formed by the bonding layer 40. However, the present invention is not limited to this, and as shown in Fig. 9, the decorative sheet 20 may be overlaid on the display device 10 from the second surface 20b formed by the decorative layer 30. The decorative sheet 20 may be overlaid on the display device 10 from a surface formed by a layer other than the bonding layer 40.

[0147] 9, the decorative layer 30 includes, in the first direction D1 from the first surface 30a to the second surface 30b, a design layer 32, a light-shielding layer 33, and a base layer 31, in this order. The design layer 32 is located closer to the viewer than the light-shielding layer 33. The light-shielding layer 33 is located between the base layer 31 and the design layer 32 in the first direction D1.

[0148] As shown in FIG. 9, the display system 1 may include a joint 15 located between the display device 10 and the decorative sheet 20. The decorative sheet 20 may be overlaid on the display device 10 via the joint 15. The illustrated joint 15 is located between the display device 10 and the decorative sheet 20 in the first direction D1. The joint 15 is joined to the display device 10 and the decorative sheet 20. The joint 15 is capable of transmitting image light emitted from the display device 10 in a display state. The joint 15 may be transparent.

[0149] The bonding portion 15 may contain a thermoplastic resin. The thermoplastic resin contained in the bonding portion 15 may contain one or more of the materials described above as the thermoplastic resin contained in the bonding layer 40. The bonding portion 15 may also contain the cured resin described above.

[0150] To ensure sufficient bonding strength, a lower limit may be set for the thickness of the bonding portion 15, i.e., its length in the first direction D1. The thickness of the bonding layer may be 10 μm or more, or 25 μm or more. Furthermore, to display an image clearly, an upper limit may be set for the thickness of the bonding portion 15. The thickness of the bonding portion 15 may be 100 μm or less, or 75 μm or less.

[0151] The initial value of the yellowness index of the joint 15 may be 2.0 or less, or may be 1.0 or less. The yellowness index of the joint 15 may be 3.5 or less, or may be 2.0 or less. The yellowness index and yellowness index of the joint 15 are measured by the method described above. By setting upper limits for the yellowness index and yellowness index of the joint 15, it is possible to prevent the image formed by light transmitted through the joint 15 and the decorative member 25 from turning yellow over time. Therefore, in such a display system 1, the image quality of the image light can be improved.

[0152] The initial value of the yellowness of the bonding portion 15 may be -5.0 or more, or may be -2.0 or more. By setting a lower limit for the initial value of the yellowness of the bonding portion 15, it is possible to prevent the image light transmitted through the bonding portion 15 from appearing bluish. No particular lower limit is set for the yellowness of the bonding portion 15. The yellowness of the bonding portion 15 may be -2.0 or more. The yellowness of the bonding portion 15 may be -1.0 or more. The material of the bonding portion 15 may be the same as that of the bonding layer 40 of the decorative sheet 20. The bonding portion 15 may be formed from the above-mentioned adhesive sheet. [Example]

[0153] An embodiment of the present disclosure will be described in more detail using examples, but the present disclosure is not limited to these examples.

[0154] Decorative sheets according to Examples 1 to 4 and decorative sheets according to Comparative Examples 1 and 2 were produced. Each decorative sheet included a decorative layer including a base layer and a design layer, and a bonding layer superimposed on the decorative layer in a first direction. The design layer was located between the base layer and the bonding layer. Each decorative sheet also included a light-shielding layer. The light-shielding layer was located between the design layer and the bonding layer.

[0155] Example 1 The decorative sheet according to Example 1 was produced by the following method. First, a decorative layer was produced. A transparent acrylic film with a thickness of 75 μm was used as the base film. A decorative film was printed on one side of the base film by gravure printing. A black ink containing carbon black was applied to the decorative film by gravure coating to form a light-shielding film. In this way, a laminate was produced that included a light-shielding film, a decorative film, and a base film in this order.

[0156] Next, a portion of the decorative film and a portion of the light-shielding film were removed by laser etching. An infrared laser processing device was used for the laser etching. Laser light was irradiated onto the laminate in the order of the light-shielding film and the decorative film. The portions of the decorative film and the light-shielding film that were irradiated with the laser light were removed. In this way, a decorative layer was produced. The produced decorative layer included a base layer, a design layer, and a light-shielding layer, in that order. The total thickness of the design layer and the light-shielding layer was 10 μm.

[0157] The produced decorative layer included a textured surface. The textured surface included multiple recesses and multiple protrusions. The portions removed by laser etching formed the recesses. The light-shielding film and the design film formed the protrusions. Multiple recesses were arranged two-dimensionally on the textured surface. The decorative layer did not include either a design layer or a light-shielding layer in the recesses. The recesses had a circular shape when observed from the direction where the base layer, design layer, and light-shielding layer overlap. The openings of the recesses were formed by the design layer. The openings had a diameter of 70 μm. The distance between adjacent recesses was 90 μm.

[0158] Next, a bonding layer was formed on the decorative layer. An adhesive sheet made of acrylic material A and having a thickness of 50 μm was brought into contact with the uneven surface of the laminate and pressed against the decorative layer with a force of 2 kg using a rubber roller. In this state, the rubber roller was moved back and forth once. The adhesive sheet contained acrylic. In this way, the decorative sheet of Example 1 was produced.

[0159] <Example 2> In the decorative sheet of Example 2, unlike Example 1, an adhesive sheet made of acrylic material B was used to form the bonding layer. The adhesive sheet contained acrylic. The adhesive sheet had a thickness of 50 μm. The decorative sheet of Example 2 was produced by the same method as the decorative sheet of Example 1, except for the adhesive sheet.

[0160] Example 3 The decorative sheet according to Example 3 was produced by the same method as the decorative sheet according to Example 2, except for the thickness of the adhesive sheet. In producing the decorative sheet according to Example 3, the adhesive sheet had a thickness of 25 μm.

[0161] Example 4 The decorative sheet according to Example 4 had the same configuration as the decorative sheet according to Example 2, except for the thickness of the adhesive sheet. When producing the decorative sheet according to Example 4, the adhesive sheet had a thickness of 100 μm.

[0162] <Comparative Example 1> The decorative sheet according to Comparative Example 1 differs from Example 1 in that an adhesive sheet made of a styrene rubber-based material was used to form the bonding layer. The adhesive sheet had a thickness of 50 μm. The decorative sheet according to Comparative Example 1 was produced by the same method as the decorative sheet according to Example 1, except for the adhesive sheet.

[0163] <Comparative Example 2> Except for the thickness of the adhesive sheet, the adhesive sheet according to Comparative Example 2 was produced by the same method as the decorative sheet according to Comparative Example 1. In producing the decorative sheet according to Comparative Example 2, the adhesive sheet had a thickness of 100 μm.

[0164] <Comparative Example 3> An attempt was made to produce a decorative sheet according to Comparative Example 3. The same method as for the decorative sheet according to Example 2 was used to produce the decorative sheet according to Comparative Example 3, except for the thickness of the adhesive sheet. The adhesive sheet had a thickness of 12 μm. However, when producing the decorative sheet according to Comparative Example 3, even when a rubber roller was used, the bonding layer did not sufficiently conform to the recesses of the decorative layer, and the adhesive sheet and decorative layer could not be stably pressure-bonded. Air remained in the openings of the decorative sheet, and when pressure treatment was performed to remove the air, deformation occurred in the substrate. As a result, the decorative sheet according to Comparative Example 3 could not be produced. The entry "N / A" in "Comparative Example 3" in Table 1 below indicates that the decorative sheet could not be produced, and therefore the physical property values ​​described below were not measured or evaluated.

[0165] <Initial value of yellowness of decorative sheet> The initial yellowness values ​​of the decorative sheets according to Examples 1 and 2 and Comparative Examples 1 and 2 were measured by the above-mentioned method. The measurement results are shown in the "Decorative Sheet" column of "Initial Yellowness Value [-]" in Table 1 below. Note that the initial yellowness values ​​of the decorative sheets according to Examples 3 and 4 and Comparative Example 2, which are marked with "-" in the column, were not measured.

[0166] <Yellowing of decorative sheet> The yellowing degree was measured by the above-mentioned method for the decorative sheets according to Examples 1 and 2 and Comparative Examples 1 and 2. The measurement results are shown in the "Decorative Sheet" column of "Yellowing Degree [-]" in Table 1 below. Note that the yellowing degree was not measured for the decorative sheets according to Examples 3 and 4 and Comparative Example 2, which are marked with "-" in the column.

[0167] <Peeling force> The peel strength was measured by the above-mentioned method for the decorative sheets according to Examples 1 to 4 and the decorative sheets according to Comparative Examples 1 and 2. The measurement results are shown in the "Peel strength [N / 25 mm]" column in Table 1 below.

[0168] <Total light transmittance of bonding layer> The bonding layer was peeled off from the decorative sheets according to Examples 1 to 4 and Comparative Examples 1 and 2. For each decorative sheet, the bonding layer was peeled off from a different sample than the samples used in Evaluations 1 and 2 described below. The total luminous transmittance of the peeled bonding layer was measured. The total luminous transmittance was measured using a haze meter (HM-150) manufactured by Murakami Color Research Laboratory Co., Ltd., in accordance with the measurement method specified in JIS K 7375:2008. The measurement environment was a temperature of 23±2°C and a relative humidity of 50%±5%. The measurement results are shown in the "Bonding Layer" column under "Total Luminous Transmittance [%]" in Table 1 below. The peeled bonding layer was used to measure the initial yellowness of the bonding layer, the yellowing of the bonding layer, the storage modulus, the maximum thickness of the bonding layer, and the transmission haze. A different bonding layer was used for each measurement.

[0169] <Initial value of yellowness of bonding layer> For the decorative sheets according to Examples 1 to 4 and the decorative sheets according to Comparative Examples 1 and 2, the initial yellowness of the bonding layer was measured by the method described above. The bonding layer used for measuring the total light transmittance was used to measure the initial yellowness. The measurement results are shown in the "bonding layer" column of "initial yellowness" in Table 1 below. Note that for the decorative sheets according to Examples 3 and 4, for which "-" is written in the column, the initial yellowness of the bonding layer was not measured.

[0170] <Yellowing of bonding layer> The yellowing degree was measured by the above-mentioned method for the decorative sheets according to Examples 1 to 4 and the decorative sheets according to Comparative Examples 1 and 2. The measurement results are shown in the "bonding layer" column of "yellowing degree" in Table 1 below. Note that for the decorative sheets according to Examples 3 and 4, for which "-" is written in the column, the yellowing degree of the bonding layer was not measured.

[0171] <Height difference of uneven surface and maximum thickness of bonding layer> The height difference of the uneven surface and the maximum thickness of the bonding layer were measured using the above-mentioned methods for the decorative sheets according to Examples 1 to 4 and Comparative Examples 1 and 2. For each decorative sheet, the height difference of the uneven surface was measured by observing the cross section of the decorative sheet using an optical microscope, as described above. For each decorative sheet, the maximum thickness of the bonding layer was measured using a digital micro stand and a digital micrometer, as described above. The measurement results for the height difference of the uneven surface are shown in the "Height difference of uneven surface [μm]" column in Table 1. The measurement results for the maximum thickness of the bonding layer are shown in the "Maximum thickness of bonding layer [μm]" column in Table 1 below.

[0172] The numerical value in the column "Height difference of uneven surface [μm]" in "Comparative Example 3" of Table 1 is the measurement result of the uneven surface of the decorative layer used in producing the decorative sheet according to Comparative Example 3. The numerical value in the column "Maximum thickness of bonding layer [μm]" in "Comparative Example 3" of Table 1 is the measurement result of the adhesive sheet used in producing the decorative sheet according to Comparative Example 3. The maximum thickness of the adhesive sheet was measured using the above-mentioned digimicro stand and digital micrometer.

[0173] <Magnification> The magnification of the maximum thickness of the bonding layer relative to the height difference of the uneven surface was calculated for the decorative sheets according to Examples 1 to 4 and the decorative sheets according to Comparative Examples 1 and 2. The calculation results are shown in the "Magnification [-]" column in Table 1 below.

[0174] <Transmittance haze> The transmission haze of the bonding layer was measured using the above-mentioned haze meter for the decorative sheets according to Examples 1 to 4 and the decorative sheets according to Comparative Examples 1 and 2. The measurement results are shown in the column "Transmission haze of bonding layer [%]" in the following Table 1. Note that for the decorative sheet according to Example 4, for which "-" is entered in the column, the transmission haze of the bonding layer was not measured.

[0175] <Rating 1> The decorative sheets according to Examples 1 to 4 and Comparative Examples 1 and 2 were attached to the display surface of a commercially available liquid crystal display device from the bonding layer side. White light was projected onto the entire display surface of the liquid crystal display device, and the presence or absence of shadows in the image observed through the decorative sheet was observed. The observation results are shown in the "Evaluation 1" column in Table 1 below. "A": No point-like shadows were observed in the image. "B": One point-like shadow less than 2 mm in diameter was observed in the image.

[0176] <Rating 2> The decorative sheets according to Examples 1 to 4 and Comparative Examples 1 and 2 were placed in a constant temperature dryer DRN420DE (manufactured by Advantec Toyo Kaisha Ltd.) set at 110° C. for 1000 hours. A commercially available liquid crystal display device was prepared. White light was displayed across the entire display surface of the liquid crystal display device. This state was observed by 10 observers. The decorative sheets according to Examples 1 to 4 and Comparative Examples 1 and 2, which had been removed from the constant temperature dryer, were placed on the display surface of the liquid crystal display device. Each decorative sheet was placed on the display device from the bonding layer. White light was displayed across the entire display surface of the liquid crystal display device, and the color of the image observed through the decorative sheet was observed. The observation results are shown in the "Evaluation 2" column in Table 1 below. "A": No difference in the color of the image due to the attachment of the decorative sheet was observed by any of the observers. "B": The difference in color of the image due to the attachment of the decorative sheet was observed by 1 to 5 observers. "C": A difference in the color of the image due to the attachment of the decorative sheet was observed by six or more observers.

[0177] [Table 1] [Explanation of symbols]

[0178] 1: display system, 10: display device, 11: display surface, 20: decorative sheet, 25: decorative member, 30: decorative layer, 31: base layer, 32: design layer, 33: light-shielding layer, 34: printed layer, 35: textured surface, 40: bonding layer

Claims

1. a decorative layer including a base layer and a design layer; A decorative sheet comprising: a bonding layer overlapping the decorative layer in a first direction; The design layer is located between the base layer and the bonding layer, The total light transmittance is 5.0% or more and 70% or less, The decorative sheet, wherein the initial value of yellowness index of the bonding layer is 2.00 or less, and the yellowing index of the bonding layer is 3.50 or less.

2. a decorative layer including a base layer and a design layer; A decorative sheet comprising: a bonding layer overlapping the decorative layer in a first direction; The design layer is located between the base layer and the bonding layer, The total light transmittance is 5.0% or more and 70% or less, A decorative sheet having an initial yellowness value of 10.0 or less and a yellowing index of 3.50 or less.

3. The decorative layer has an uneven surface, the bonding layer is bonded to the uneven surface, The decorative sheet according to claim 1 , wherein the maximum thickness of the bonding layer is 2.0 times or more the height difference of the concave-convex surface in the first direction.

4. The decorative sheet according to claim 3 , wherein the decorative layer includes a plurality of printed layers that form the uneven surface.

5. the uneven surface includes a plurality of recesses that open toward the bonding layer, The decorative sheet according to claim 3 , wherein each of the plurality of recesses has a shape tapered toward a bottom of the recess.

6. a decorative layer including a base layer and a design layer; A decorative sheet comprising: a bonding layer overlapping the decorative layer in a first direction; The design layer is located between the base layer and the bonding layer, The decorative layer has an uneven surface, the bonding layer is bonded to the uneven surface, The total light transmittance is 5.0% or more and 70% or less, A decorative sheet, wherein the maximum thickness of the bonding layer is 2.0 times or more the height difference of the uneven surface in the first direction.

7. The decorative sheet according to claim 6 , wherein the decorative layer includes a plurality of printed layers that form the uneven surface.

8. the uneven surface includes a plurality of recesses that open toward the bonding layer, The decorative sheet according to claim 6 , wherein each of the plurality of recesses has a shape tapered toward a bottom of the recess.

9. The decorative sheet according to claim 1 , wherein the bonding layer has a storage modulus of 1.0 MPa or less at 25° C.

10. The decorative sheet according to claim 1 , wherein the bonding layer has a storage modulus of 1.0 MPa or less at 80° C.

11. The decorative sheet according to claim 1 , wherein the bonding layer has a total light transmittance of 80% or more.

12. The decorative sheet according to claim 1 , wherein the bonding layer has a transmission haze of 2.0% or less.

13. The decorative sheet according to claim 1 , wherein the maximum thickness of the bonding layer is greater than the maximum thickness of the base layer.

14. the decorative layer includes a light-shielding layer having a light-shielding property, The decorative sheet according to claim 1 , wherein the light-shielding layer is located between the base layer and the bonding layer.

15. The decorative sheet according to claim 1 , wherein the maximum thickness of the bonding layer is 25.0 μm or more and 100 μm or less.

16. The decorative sheet according to claim 1 , wherein the bonding layer includes a cured resin.

17. The decorative sheet according to claim 1 , wherein a peel strength at the surface formed by the bonding layer is 10.0 N / 25 mm or more and 40.0 N / 25 mm or less.

18. A support member; A decorative member comprising: the decorative sheet according to claim 1 superimposed on the support member.

19. The decorative sheet according to any one of claims 1 to 6, and a display device overlaid on the decorative sheet, The decorative sheet has a first surface and a second surface opposite to the first surface, the first surface is formed by the bonding layer, the second surface is formed by the decorative layer, The decorative sheet is placed on the display device from the first surface side.

20. The decorative sheet according to any one of claims 1 to 6, and a display device superimposed on the decorative sheet; a joint portion located between the decorative sheet and the display device, The bonding portion is bonded to the decorative sheet and the bonding portion, The display system wherein the initial yellowness index of the joint is 2.00 or less, and the yellowness index of the joint is 3.50 or less.

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