Decorative sheets and decorative molded products

Abstract

The present invention provides a decorative sheet that can clearly display a light pattern when light is shone from the back. [Solution] A decorative sheet that allows a predetermined light pattern to be visible on the front side when light is shone from the back side, wherein a design layer, a core layer, and an opacity layer are laminated in this order from the front side, the design layer has a printed layer that constitutes a pattern, and the core layer has a total light transmittance of 85% or more.

Description

Technical Field

[0001] The present invention relates to a decorative sheet and a decorated molded product.

Background Art

[0002] In order to enhance the design of the interior and exterior of mobility, housings of electronic devices and robots, etc., a decorative sheet having a pattern such as a wood grain pattern is used. As a decorative sheet, there has been proposed one in which a predetermined light pattern can be visually recognized on the front surface side when irradiated with light from the back surface side (Patent Documents 1 to 4).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the case of a conventional decorative sheet, especially when the appearance of the decorative sheet has a bright color tone or a pattern, the outline of the light pattern projected on the surface is likely to be blurred compared to the case of a dark color tone or a plain surface.

[0005] An object of the present invention is to provide a decorative sheet and a decorated molded product that can clearly project a light pattern when irradiated with light from the back surface side.

Means for Solving the Problems

[0006] The present invention has the following aspects. [1] A decorative sheet that allows a predetermined light pattern to be visible on the surface when light is shone from the back, From the surface side, the design layer, core layer, and concealment layer are laminated in this order. The aforementioned design layer has a printed layer that constitutes the pattern, The core layer is characterized by having a total light transmittance of 85% or more, and is a decorative sheet. [2] The decorative sheet according to [1], wherein the design layer has a transparent surface layer on the surface side of the printed layer. [3] The decorative sheet according to [1] or [2], wherein the design layer has a colored layer on the back side of the printed layer. [4] The decorative sheet according to any one of [1] to [3] above, wherein the design layer is laminated in the following order from the surface side: a transparent surface layer, the printing layer, and the coloring layer. [5] The decorative sheet according to [2] or [4], wherein the surface of the transparent surface layer has irregularities formed on it. [6] The core layer is a decorative sheet according to any one of [1] to [5], made of polycarbonate resin. [7] The decorative sheet according to any one of [1] to [6], wherein the concealing layer comprises a light-shielding portion and a light-transmitting portion, and the light-transmitting portion has the same shape as the light pattern. [8] A decorative molded product having been formed from any of the decorative sheets described in [1] to [7] above. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a decorative sheet and a decorative molded product that can clearly display a light pattern when light is irradiated from the back side. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing the layer structure of the decorative sheet according to the embodiment. [Figure 2] This is a cross-sectional view showing the layer structure of the decorative sheet of Comparative Example 2. [Figure 3] This is a photograph of the decorative molded product of Example 1, taken when the light source was illuminated, showing the light pattern display area on the surface. [Figure 4] This is a photograph of the decorative molded product of Comparative Example 1, taken when the light source is lit and showing the light pattern display portion on the surface. [Figure 5] This is a photograph of the decorative molded product of Comparative Example 2, taken when the light source is lit and showing the light pattern display portion on the surface.

Embodiments for Carrying out the Invention

[0009] The following definitions of terms apply throughout this specification and the claims. The "back side" of the decorative sheet is the side on which the light source for projecting the light pattern is arranged. The "front side" of the decorative sheet is the side opposite to the back side and is the side visible to the viewer. The "total light transmittance" is measured in accordance with JIS K7361-1:1997. The "haze" is measured in accordance with JIS K7136:2000. The "~" indicating a numerical range means that the numerical values described before and after it are included as the lower limit value and the upper limit value.

[0010] Hereinafter, a decorative sheet according to an embodiment of the present invention will be described. The following embodiments are specifically described to better understand the gist of the invention, and unless otherwise specified, they do not limit the present invention.

[0011] FIG. 1 is a cross-sectional view showing the layer structure of the decorative sheet 1 of this embodiment. Note that the dimensional ratios in FIG. 1 are different from the actual ones for the convenience of explanation. The decorative sheet 1 is formed by laminating a design layer 2, a core layer 3, and a concealment layer 4 in this order from the front side (the upper side in the figure). The surface of the core layer 3 is in contact with the back of the design layer 2. The surface of the concealment layer 4 is in contact with the back of the core layer 3. When the decorative sheet 1 is irradiated with light from a light source 100 arranged on the back side (the lower side in the figure) of the decorative sheet 1, a predetermined light pattern can be visually recognized on the front side.

[0012] In order to make a predetermined light pattern visible on the surface side, at least a portion of the concealing layer 4, the design layer 2, and the core layer 3 are translucent. In this embodiment, the concealing layer 4, when viewed from above, consists of a light-shielding portion 41 and a light-transmitting portion 42. The light-transmitting portion 42 has the same shape as the light pattern to be projected onto the surface of the decorative sheet 1. When light is shone from the light source 100, the light that passes through the light-transmitting portion 42 of the concealing layer 4 passes through the core layer 3 and the design layer 2, and a light pattern with a shape corresponding to the light-transmitting portion 42 is projected onto the surface of the decorative sheet 1.

[0013] (Design layer) The design layer 2 is constructed by laminating a transparent surface layer 22, a printed layer 21 that constitutes the design, and a colored layer 23 in that order from the surface side. The transparent surface layer 22 is located on the surface of the decorative sheet 1. When light is not shining on the decorative sheet 1 from the back, the pattern of the printed layer 21 is visible from the front.

[0014] The thickness of the design layer 2 is preferably 0.05 to 0.5 mm, and more preferably 0.08 to 0.3 mm. If the thickness of the design layer 2 is below the above upper limit, light from the core layer 3 side will easily pass through, and if it is above the above lower limit, the pattern will be easily visible on the front side when light is not shining from the back side.

[0015] The total light transmittance of the design layer 2 is preferably 20% or less, and more preferably 10% or less. If the total light transmittance of the design layer 2 is below the above upper limit, light from the core layer 3 side will pass through easily, and if it is above the above lower limit, the pattern will be easily visible on the front side when light is not shining from the back side. The brightness of design layer 2 is L * A value of 10 or more is preferable, and 30 or more is more preferable. L * The values ​​are from JIS Z 8781-4:2013 "Colorimetry - Part IV: CIE 1976 L * a * b * This is a correlation quantity of lightness as defined in the color space (corresponding international standard ISO 11664-4:2008).

[0016] "Print layer" The pattern on the printed layer 21 is not particularly limited and may be any pattern used on known decorative sheets. Examples include wood grain patterns, stone patterns, sand patterns, fabric patterns, tile patterns, brick patterns, leather patterns, geometric patterns, metallic patterns, letters, symbols, etc. The ink used to form the printed layer 21 is not particularly limited, and any known ink can be used depending on the printing method. For example, an ink composition containing a binder resin and a pigment can be used. Examples of binder resins include acrylic resins, vinyl chloride-vinyl acetate resins, vinyl acetate resins, urethane resins, polyester resins, and the like. Printing methods include, for example, gravure printing, screen printing, flexographic printing, letterpress printing, and inkjet printing. Gravure printing is preferred because it can reproduce images with high resolution. The printed layer 21 may be formed over the entire surface of the design layer 2 or only partially. The printing layer 21 may be a single layer or multiple layers. The thickness of the printed layer 21 is, for example, 0.1 to 10 μm, or even 1 to 5 μm.

[0017] "Transparent surface layer" The transparent surface layer 22 is located on the surface of the decorative sheet 1. The transparent surface layer 22 is not essential, but having the transparent surface layer 22 protects the printed layer 21 from friction, impact, scratches, etc.

[0018] The total light transmittance of the transparent surface layer 22 is preferably 70% or more, and more preferably 85% or more. The haze of the transparent surface layer 22 is preferably 10% or less, and more preferably 5% or less.

[0019] The transparent surface layer 22 may include, for example, a layer containing a transparent resin. Examples of transparent resins include acrylic resins, vinyl chloride resins, polycarbonate resins, urethane resins, polyester resins, etc. The layer containing the transparent resin may also contain additives to the extent that it does not impair transparency. The layer containing the transparent resin may be a layer of a transparent film containing the transparent resin. Such a film can also be used as a substrate for forming the printed layer 21.

[0020] The surface of the transparent surface layer 22 may be smooth, but it is preferable that it has irregularities. When irregularities are formed on the surface of the transparent surface layer 22, the appearance of the pattern from the surface side and the feel and texture of the surface of the decorative sheet 1 can be adjusted. Examples of uneven shapes include wood grain-like structures, stone-like structures, cloth-like structures, Japanese paper-like structures, suede-like structures, leather-like structures, pear-skin-like structures, sand-like structures, hairline-like structures, grid-like structures, and geometric patterns. The height of the surface irregularities is, for example, 0.01 to 10 μm. The height of the irregularities is measured, for example, by a surface roughness meter.

[0021] The transparent surface layer 22 may be a single layer or a multilayer layer. The thickness of the transparent surface layer 22 is, for example, 10 to 400 μm, or even 30 to 200 μm. If the surface of the transparent surface layer 22 has irregularities, the thickness of the transparent surface layer 22 is the thickness of the convex portion. The same applies to the overall thickness of the design layer 2.

[0022] "Colored layer" The colored layer 23 is located on the back side of the printed layer 21. The colored layer 23 is not essential, but by providing it, the colored layer 23 becomes the background for the design on the printed layer 21, making the design easier to see. Also, if the opacity layer 4 consists of a light-transmitting portion and a light-blocking portion, especially if the light-blocking portion is a dark color such as black, it is possible to suppress the visibility of the pattern of the light-blocking portion from the front side through the design layer 2 when light is not shining from the back side. Examples of the colors of the colored layer 23 include white, ivory, and yellow.

[0023] The colored layer 23 may include, for example, a layer containing a resin and a coloring agent such as a pigment. Examples of resins include vinyl chloride resins, acrylic resins, and polycarbonate resins. As the coloring agent, known coloring agents can be used depending on the color tone of the colored layer 23. It may also contain additives other than coloring agents. The layer containing the resin and colorant may be a layer of a colored film containing the resin and a colorant such as a pigment. Such a film can also be used as a substrate for forming the printed layer 21.

[0024] The colored layer 23 may be a single layer or multiple layers. The thickness of the colored layer 23 is, for example, 10 to 400 μm, or even 30 to 200 μm.

[0025] (Core layer) The presence of a core layer 3 in the decorative sheet 1 gives the decorative sheet 1 mechanical strength and durability. For example, when the decorative sheet 1 is molded into a three-dimensional shape, the decorative sheet 1 can maintain that shape on its own.

[0026] The total light transmittance of the core layer 3 is 85% or higher, preferably 88% or higher, and more preferably 90% or higher. A total light transmittance of 85% or higher in the core layer 3 makes the light pattern projected onto the surface clear. This is because, when light is shone from the back of the decorative sheet 1, the light that passes through the concealing layer 4 travels in a straight line without scattering, reaching the surface while maintaining sufficient light intensity.

[0027] The haze of the core layer 3 is preferably 5% or less, and more preferably 1% or less. When the haze of the core layer 3 is below the above upper limit, the straightness of light transmitted through the core layer 3 is improved, and the light pattern projected on the surface becomes clearer.

[0028] Examples of materials for the core layer 3 include transparent resins such as polycarbonate resin, acrylic resin, vinyl chloride resin, urethane resin, and polyester resin. In addition to the transparent resin, the core layer 3 may also contain additives, as long as the total light transmittance does not fall below the above lower limit.

[0029] The core layer 3 may be a single layer or a multilayer. It is preferable in terms of moldability to make the core layer 3 a multilayer with different materials for each layer. An example of a multilayer core layer 3 is a two-layer structure in which a layer of first polycarbonate resin and a layer of second polycarbonate resin having a different melting point from the first polycarbonate resin are laminated, and the layer with the lower melting point is positioned facing the design layer 2.

[0030] The thickness of the core layer 3 is preferably 0.1 to 5 mm, and more preferably 0.5 to 3 mm. If the thickness of the core layer 3 is above the lower limit, the mechanical strength and durability are better, and if it is below the upper limit, the moldability is better.

[0031] (Concealing layer) The decorative sheet 1 has an opaque layer 4, which prevents the back side (light source 100, etc.) from being visible from the front side of the decorative sheet 1 when light is not irradiated from the back.

[0032] As described above, the concealing layer 4, when viewed from above, consists of a light-shielding portion 41 and a light-transmitting portion 42, and the light-transmitting portion 42 has the same shape as the light pattern that is intended to be projected onto the surface of the decorative sheet 1. The thickness of the concealing layer 4 is, for example, 1 to 1000 μm, or even 3 to 500 μm.

[0033] The material and method of forming the light-shielding portion 41 are not particularly limited, as long as it has light-shielding properties. Examples of the light-shielding portion 41 include a light-shielding ink layer formed from a light-shielding ink such as black ink, and a layer made of a light-shielding sheet processed into a shape corresponding to the light-shielding portion 41. The light-shielding portion 41 may be a single layer or multiple layers. The total light transmittance of the light-shielding portion 41 is preferably 5% or less, and more preferably 3% or less.

[0034] In this embodiment, the back surface of the core layer 3 is partially exposed, and the space enclosed by the back surface of the core layer 3 and the side surface of the light-shielding portion 41 is defined as the light-transmitting portion 42. A light-transmitting layer may be formed on the back of the core layer 3 at a position corresponding to the light-transmitting portion 42, thereby forming the light-transmitting portion 42. Examples of the light-transmitting layer include a light-transmitting ink layer formed from a light-transmitting ink. The light-transmitting layer may be a single layer or a multi-layer layer. The translucent layer may be colored. In this case, the translucent layer can change the color tone of the light from light source 100. If there are multiple translucent layers, the color tones of each translucent layer may be the same or different. The total light transmittance of the light-transmitting portion 42 is preferably 50% or more, and more preferably 70% or more.

[0035] In this embodiment, an example is shown where the concealing layer 4 consists of a light-shielding portion 41 and a light-transmitting portion 42, but the concealing layer 4 is not limited to this. For example, the entire concealing layer 4 may be light-transmitting. When a light source 100 is used that can emit light in a shape corresponding to the desired light pattern, or when multiple light sources are placed on the back side of the decorative sheet 1 and a light pattern is formed by controlling the on / off state of the multiple light sources, the light pattern can be displayed even if the entire concealing layer 4 is light-transmitting.

[0036] (Method of manufacturing decorative sheets) The decorative sheet 1 can be manufactured, for example, as follows: First, the design layer 2 and the core layer 3 are laminated and then hot-pressed to obtain a sheet-like first laminate. The hot-pressing conditions are, for example, 150 to 180°C. The design layer 2 can be manufactured by sequentially laminating a transparent surface layer 22, a printed layer 21, and a colored layer 23. Commercially available products may also be used.

[0037] If necessary, embossing is applied to the transparent surface layer 22 side of the first laminate to form irregularities. Embossing can be carried out by known methods. For example, it can be carried out by placing a press plate having an embossed pattern on the transparent surface layer 22 side of the first laminate and performing a heat press. The heat press conditions are, for example, 150 to 180°C. When embossing is performed by heat press, the heat press used when laminating the design layer 2 and the core layer 3 may also serve as the heat press for embossing.

[0038] Next, a light-shielding portion 41 is formed on the core layer 3 side of the first laminate. Methods for forming the light-shielding portion 41 include, for example, printing on the back surface of the core layer 3 using a light-shielding ink such as black ink, or processing a light-shielding sheet into a shape corresponding to the light-shielding portion 41 and placing it on the back surface of the core layer 3.

[0039] If necessary, a light-transmitting layer may be formed on the core layer 3 side of the first laminate in areas where the light-shielding portion 41 is not formed. The light-transmitting layer can be formed, for example, by printing using a light-transmitting ink.

[0040] (Decorative molded product) The decorative sheet 1 can be molded to produce a decorative molded product. The molding method is not particularly limited and may be any known method for molding sheets. Examples include thermoforming such as vacuum forming and injection molding. The molding temperature for thermoforming is, for example, 200 to 300°C. The applications of the decorative molded product formed from the decorative sheet 1 are not particularly limited. For example, it can be used as an interior or exterior component for mobility devices, or as a housing for electronic devices or robots. [Examples]

[0041] The present invention will be described more specifically below with reference to examples. However, the present invention is not limited to these examples.

[0042] (Example 1) A decorative sheet with the layered structure shown in Figure 1 was manufactured using the following procedure. As the design layer, a laminate was prepared in which a transparent surface layer (acrylic resin film), a printed layer with a wood grain pattern, and a colored layer (polyvinyl chloride resin film) were laminated in this order. The printed layer was formed by printing on the surface of the colored layer using gravure printing. The thickness of the design layer was 0.16 mm, and the total light transmittance was 5.78%. A laminate was prepared, consisting of a polycarbonate layer (hereinafter also referred to as polycarbonate layer A) made of 70 parts by mass of Duravio® D7340IR (polycarbonate resin, manufactured by Mitsubishi Chemical Corporation) and 30 parts by mass of Duravio® D5380R (polycarbonate resin, manufactured by Mitsubishi Chemical Corporation) as the core layer, and a polycarbonate layer (hereinafter also referred to as polycarbonate layer B) made of Caliber (product name) 300-8 (polycarbonate resin, manufactured by Sumika Polycarbonate Co., Ltd.). The thickness of the core layer was 1.5 mm, the total light transmittance was 90.82%, and the haze was 0.91%. The design layer and the core layer were stacked so that the colored layer of the design layer and the polycarbonate layer A of the core layer were adjacent to each other, and then heat-pressed and integrated using a hot press machine under the conditions of press temperature: 170°C and press time: 30 minutes. An embossed press plate was placed on the transparent surface layer side of the obtained sheet, and embossing was performed by heat pressing under the conditions of surface temperature: 170°C. An opaque layer consisting of light-transmitting and light-blocking areas of a predetermined pattern was formed on the core layer side of the embossed sheet to obtain a decorative sheet. Black light-blocking ink was applied to the light-blocking areas by screen printing and dried to form a light-blocking ink layer. Subsequently, a mold was pressed against the resulting decorative sheet, heated at 200-300°C, and vacuum forming was performed to obtain a decorated molded product.

[0043] (Comparative Example 1) A decorative sheet and a decorative molded product were obtained in the same manner as in Example 1, except that the polycarbonate layer B of the core layer was changed to a resin layer consisting of 70 parts by mass of Caliber (trade name) 300-8 (manufactured by Sumika Polycarbonate Co., Ltd.) and 30 parts by mass of ECOZEN (registered trademark) HF502 (polyester resin, manufactured by SK Chemical Co., Ltd.). The thickness of the core layer was 1.5 mm, the total light transmittance was 84.10%, and the haze was 57.72%.

[0044] (Comparative Example 2) A decorative sheet with the layered structure shown in Figure 2 was manufactured using the following procedure. The design layer and core layer were prepared in the same manner as in Example 1. The design layer and the core layer were stacked so that the transparent surface layer of the design layer and the polycarbonate layer A of the core layer were adjacent to each other, and then heat-pressed and integrated using a hot press machine under the conditions of press temperature: 170°C and press time: 30 minutes. An embossed press plate was placed on the core layer side of the obtained sheet, and embossing was performed by hot pressing at a surface temperature of 170°C. After embossing, an opaque layer was formed on the design layer side of the sheet in the same manner as in Example 1 to obtain a decorative sheet. Subsequently, a mold was pressed against the resulting decorative sheet, heated at 200-300°C, and vacuum forming was performed to obtain a decorated molded product.

[0045] (evaluation) In a darkroom, a light source was placed on the back side (opaque layer side) of the decorated molded product. An LED light source was used. The light source was turned on, and the light pattern of the decorated molded product was observed from the front side. Figures 3 to 5 show photographs of the light pattern display area on the surface of each example's decorated molded product when the light source is illuminated (Figure 3: Example 1, Figure 4: Comparative Example 1, Figure 5: Comparative Example 2). As shown in Figures 3-5, the decorated molded product of Example 1 had a clear outline of the light pattern. On the other hand, the decorated molded products of Comparative Examples 1-2 had a blurred outline of the light pattern. [Explanation of Symbols]

[0046] 1. Decorative sheet 2. Design Layer 21 Printing layer 22 Transparent surface layer 23 Colored layer 3 Core Layers 4. Concealment layer 41 Light-shielding part 42 Translucent part 100 light sources

Claims

1. A decorative sheet that allows a predetermined light pattern to be visible on the surface when light is shone from the back, From the surface side, the design layer, core layer, and concealment layer are laminated in this order. The aforementioned design layer has a printed layer that constitutes the pattern, The core layer is characterized by having a total light transmittance of 85% or more, and is a decorative sheet.

2. The decorative sheet according to claim 1, wherein the design layer has a transparent surface layer on the surface side of the printed layer.

3. The decorative sheet according to claim 1, wherein the design layer has a colored layer on the back side of the printed layer.

4. The decorative sheet according to claim 1, wherein the design layer is laminated in the following order from the surface side: a transparent surface layer, the printing layer, and the coloring layer.

5. The decorative sheet according to claim 2 or 4, wherein the surface of the transparent surface layer has irregularities formed on it.

6. The decorative sheet according to any one of claims 1 to 4, wherein the core layer is made of polycarbonate resin.

7. The decorative sheet according to any one of claims 1 to 4, wherein the concealing layer comprises a light-shielding portion and a light-transmitting portion, and the light-transmitting portion has the same shape as the light pattern.

8. A decorative molded article having a decorative sheet according to any one of claims 1 to 4.

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