Decorative member

A decorative member (1A) includes: a resin layer (2) having a front surface (2b) and a back surface (2a); and a reflective layer (3) formed on the back surface (2a) of the resin layer (2). The back surface (2a) of the resin layer (2) includes a receding surface (21) formed therein. The receding surface recedes gradually toward the front surface (2b) to change a thickness of the resin layer (2). A pigmented layer (4) configured so that lightness/depth of color thereof changes in accordance with the change in the thickness of the resin layer (2) is provided between the back surface (2a) of the resin layer (2) and the reflective layer (3).

TECHNICAL FIELD

The technique disclosed herein relates to a decorative member that exhibits a pattern having a raised three-dimensional appearance.

BACKGROUND ART

Conventionally, as a decorative member for realizing a design with a three-dimensional visual effect, Patent Literature 1 has disclosed a decorative member100as shown inFIG. 8. In the decorative member100, a transparent or translucent resin plate200has a back surface serrated with steep slopes210with a large inclination angle and gentle slopes220with a small inclination angle repeated alternately, and the back surface is covered with a colored layer300.

The colored layer300has light reflecting capability. At portions of the colored layer300facing the gentle slopes220, light that has entered the resin plate200through its front surface is reflected by the colored layer300so as to return to a front side. However, at portions of the colored layer300facing the steep slopes210, the light is reflected by the colored layer300so as to veer in a lateral direction. This allows the colored layer300to look dark at portions corresponding to the steep slopes210, forming a three-dimensional stripe pattern appearance.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In Patent Literature 1, as is apparent from the fact that the term “colored layer” is used therein, the colored layer300represents the color of the pattern of the decorative member100. However, in such a case where the colored layer300represents the color of the pattern of the decorative member100, the ridges formed by providing the colored layer300along the two slopes210,220do not look raised well, and the three-dimensional visual effect is not so high.

In view of the foregoing, the technique disclosed herein is intended to provide a decorative member with a high three-dimensional visual effect.

Solution to Problem

The above-mentioned problems is solved by a decorative member including: a colored light-transmissive resin layer having a front surface and a back surface, the back surface including a receding surface formed therein, the receding surface receding gradually toward the front surface to change a thickness that is a distance between the front surface and the back surface; a reflective layer formed on the back surface of the resin layer so as to cover the receding surface; and a pigmented layer interposed between the back surface of the resin layer and the reflective layer, the pigmented layer being configured so that lightness/depth of color thereof changes in accordance with the change in the thickness of the resin layer.

Advantageous Effects of Invention

In the above-mentioned decorative member, by changing, with the receding surface, the thickness of the colored resin layer, it is possible to form, on a convex portion formed by providing the reflective layer along the receding surface, a gradation of color that is pale at a thin portion of the resin layer and deep at a thick portion of the resin layer. Moreover, because of the transmission loss of light in the resin layer and the reflection of light by the reflective layer, the convex portion of the reflective layer along the receding surface looks bright at the thin portion of the resin layer and dark at the thick portion of the resin layer. With such a gradation having not only the lightness/depth of color but also the contrast of light utilizing the reflection of light, the convex portion of the reflective layer has a distinctly raised appearance. Thereby, a high three-dimensional visual effect can be obtained.

Furthermore, in the above-mentioned decorative member, the pigmented layer interposed between the resin layer and the reflective layer makes it possible to reduce the thickness of the resin layer while maintaining the high three-dimensional visual effect.

DESCRIPTION OF EMBODIMENTS

FIGS. 1 to 3show a decorative member1A according to Embodiment 1 of the present invention. The decorative member1A has an approximately rectangular plate-like shape extending in a specified direction. The decorative member1A has a resin layer2on a front side (on a bottom side inFIGS. 1 to 3), and a reflective layer3on a back side (on a top side inFIGS. 1 to 3).

The resin layer2is colored and light-transmissive. More specifically, the resin layer2allows light in a specified wavelength range of a visible light range to transmit therethrough, and absorbs or reflects light other than this. The color of the resin layer2is not particularly limited. Preferably, a relatively deep color (for example: black, red, and blue; or ACRYLITE produced by Mitsubishi Rayon Co., Ltd., color tone No. 530 (blue smoke), No. 540 (green smoke), No. 550 (brown smoke), and No. 83 (gray smoke)) is used. As the material composing the resin layer2, various polymers, such as an acrylic resin, polycarbonate, ABS (acrylonitrile butadiene styrene), polyamide, and nylon, can be used independently or in combination as a polymer alloy.

The resin layer2has a front surface2bthat is one surface in a thickness direction thereof, and a back surface2athat is the other surface in the thickness direction. The front surface2bis a flat surface perpendicular to the thickness direction of the resin layer2. In the back surface2a, a receding surface21is formed. The receding surface21recedes gradually toward the front surface2bto change a thickness that is a distance between the front surface2band the back surface2a. In the present embodiment, the back surface2aincludes, outside the receding surface21, a reference surface22that is parallel to the front surface2b(in other words, the reference surface22is a flat surface perpendicular to the thickness direction of the resin layer2.)

The receding surface21is curved continuously along at least one direction perpendicular to the thickness direction of the resin layer2so as to be convex toward the front surface2b. As stated herein, the phrase “to be curved continuously” means that the gradient of a tangent of a cross-sectional shape of the receding surface21in a direction in which the receding surface21is curved varies in one-way direction from one end to the other end of the cross-sectional shape substantially continuously. It should be noted that the receding surface21may be formed in a linear curving manner with a constant curvature, or in a non-linear curving manner with a variable curvature. The term “substantially” indicates a concept including a case where: concave and convex portions such as those remaining on the surface during processing are ignored; and the gradient of a tangent of a cross-sectional shape of the receding surface21varies in one-way direction from one end to the other end of the cross-sectional shape continuously in a shape recognizable by human vision.

In the present embodiment, the receding surface21is a concave surface forming a depression that opens while broadening. In other words, the cross-sectional shape of the receding surface21in the direction in which the receding surface21is curved extends from one end to the other end so as to come closer to the front surface2band then go away therefrom. Furthermore, the concave surface of the present embodiment has a dome shape curved continuously along a longer direction and a shorter direction of the decorative member1A (two directions perpendicular to each other and to the thickness direction of the resin layer2.) The reference surface22surrounds the receding surface21.

The shape of the receding surface21in a plan view is not particularly limited. Preferably, the receding surface21extends in the longer direction of the decorative member1A. For example, the shape of the receding surface21may be an elliptical shape or a strip-like shape with both ends being roundish, when viewed from the thickness direction of the resin layer2.

A peripheral portion of the receding surface21may be joined directly to the reference surface22angularly so as to form a ridgeline with the reference surface22. Alternatively, there may be provided a joint, having a cross-sectional shape that is convex in the direction opposite to that of the receding surface21, annularly between the peripheral portion of the receding surface21and the reference surface22, and the peripheral portion of the receding surface21may be joined smoothly to the reference surface22via the joint.

The resin layer2as mentioned above can be molded by a molding method such as injection molding, heating compression molding, and a combination of extrusion molding and heating compression molding. In molding the resin layer2, it is preferable to use a mirror-finished metal mold in order to prevent the irregular reflection of light by the front surface2band to enhance the texture.

The reflective layer3is formed on the back surface2aof the resin layer2so as to cover the receding surface21and the reference surface22. The reflective layer3serves to reflect the light that has transmitted through the resin layer2. Preferably, the reflective layer3essentially blocks light in the visible light range (approximately 400 to 750 nm) from transmitting therethrough, and has high reflectance to light essentially throughout the visible light range. From the viewpoint of regularly reflecting the light that has transmitted through the resin layer2, a front surface of the reflective layer3contacting the receding surface21and the reference surface22of the resin layer2preferably is a lustrous smooth surface. For example, the transmittance of the reflective layer3to visible light preferably is 5% or less, more preferably 1% or less, and particularly preferably 0.1% or less. The reflectance and the smooth surface are expressed in terms of a gloss (luster) value of the front surface of the reflective layer3. When the gloss value in the case where the brightness difference between incident light and receiving light is 10%, with the incident angle being 60 degree and the receiving angle being −60 degree on a glass surface (with a refractive index of 1.567), is taken as 100, the gloss value of the front surface of the reflective layer3preferably is 200 or more, more preferably 700 or more, and particularly preferably about 800.

Furthermore, the reflective layer3preferably has a metallic color. The reflective layer3can be composed of, for example: a coating film formed by coating a coating material containing a metallic pigment or a metallic colorant, or by printing a metallic ink; a metal film formed by vapor-depositing metal such as aluminum; or a metallic-colored sheet bonded to the back surface2aof the resin layer2.

In the present embodiment, a pigmented layer4further is provided between the back surface2aof the resin layer2and the reflective layer3. The pigmented layer is configured so that lightness/depth of color thereof changes in accordance with the change in the thickness of the resin layer. The pigmented layer4as a whole allows light in a visible light range to transmit therethrough. In the pigmented layer4, the amount of light in a visible light that transmits a deep-colored portion is smaller than that transmitting a pale-colored portion.

Specifically, on the receding surface21, the pigmented layer4is composed of dots whose density increases as the thickness of the resin layer2increases. Such dots can be formed by a printing technique using an ink. As the printing technique, gravure printing or screen printing is used suitably. On the reference surface22, the pigmented layer4may be composed of dots with a density comparable to that of the dots on the peripheral portion of the receding surface21, or may be composed of a coating film formed by printing the ink on the entire reference surface22.

In the decorative member1A of the present embodiment described above, by changing, with the receding surface21, the thickness of the colored resin layer2, it is possible to form, on the convex portion formed by providing the reflective layer3along the receding surface21, a gradation of color that is pale at the thin portion of the resin layer2and deep at the thick portion of the resin layer2as shown inFIG. 4. Moreover, because of the transmission loss of light in the resin layer2and the reflection of light by the reflective layer3, the convex portion of the reflective layer3along the receding surface21looks bright at the thin portion of the resin layer2and dark at the thick portion of the resin layer2. With such a gradation having not only the lightness/depth of color but also the contrast of light utilizing the reflection of light, the convex portion of the reflective layer3has a distinctly raised appearance. Thereby, a high three-dimensional visual effect can be obtained.

Furthermore, in the decorative member1A of the present embodiment, the pigmented layer4interposed between the resin layer2and the reflective layer3makes it possible to reduce the thickness of the resin layer2while maintaining the high three-dimensional visual effect. In the case where the pigmented layer4is not provided, the thickness of the resin layer2is the only factor for defining the lightness/depth of color in the gradation. Therefore, in order to obtain a high three-dimensional visual effect, it is necessary to increase the thickness of the resin layer2to some extent and increase the level difference between the top and the bottom of the receding surface21(the distance over which the receding surface21recedes in the thickness direction of the resin layer2). However, in the case where the level difference in the receding surface21is increased in this way, warpage and weld occur when the resin layer2is molded by, for example, injection molding, which decreases the yield. In contrast, in the case where the pigmented layer4is provided between the resin layer2and the reflective layer3as in the present embodiment, the lightness/depth of color in the gradation can be defined also by the lightness/depth of color of the pigmented layer4. This makes it possible to obtain a comparable three-dimensional visual effect even when the level difference in the receding surface21is reduced and the thickness of the resin layer2is reduced. As a result, it is possible to suppress a decrease in the yield at the time of molding the resin layer2and to reduce the manufacturing cost.

In addition, in the decorative member1A of the present embodiment, since the receding surface21is curved continuously, it is possible to change gradually and minutely the lightness/depth of color and the contrast of light in the gradation from the thin portion of the resin layer to the thick portion of the resin layer. Moreover, the degree of the gradation formed on the convex portion of the reflective layer3varies in accordance with the angle at which the decorative member1A is viewed. Thereby, the three-dimensional visual effect can be accentuated further.

Furthermore, in the decorative member1A of the present embodiment, the reference surface22is provided outside the receding surface21. The normal direction of the front surface of the reflective layer3becomes lateral gradually from the bottom of the receding surface21toward the peripheral portion, and accordingly the colored resin layer2looks darker gradually. At a portion right above the peripheral portion of the receding surface21, the darkness reaches its peak and the resin layer2looks blackish. In contrast, at the thickest portion at which the thickness of the resin layer2defined by the reference surface22is largest, the reflective layer3is parallel to the front surface2b. For this reason, at the thickest portion, the colored resin layer2looks deeper in color than at the thinnest portion at which the thickness of the resin layer2defined by the bottom of the receding surface21is smallest, and paler than at the portion right above the peripheral portion of the receding surface21. Thereby, the darkness at the peripheral portion of the receding surface21is accentuated in comparison with the reference surface22, and a higher three-dimensional visual effect can be obtained.

Next,FIGS. 5A and 5Bshow a decorative member1B according to Embodiment 2 of the present invention. In the present embodiment, the same components as those in Embodiment 1 are indicated with the same reference numerals, and the descriptions thereof are omitted.

In the decorative member1B of the present embodiment, a concave surface forming a groove-like depression extending in a longer direction of the decorative member1B is formed, as the receding surface21, in the back surface2aof the resin layer2. That is, the concave surface has a cylindrical shape curved continuously along only a shorter direction (one direction perpendicular to the thickness direction of the resin layer2) of the decorative member1B. Thereby, a gradational pattern, as shown inFIG. 5A, having a three-dimensional visual effect is expressed in the decorative member1B.

Also in the gradation shown inFIG. 5A, the lightness/depth of color and the contrast of light in the gradation change gradually and minutely from the thin portion of the resin layer to the thick portion of the resin layer, as in Embodiment 1. Furthermore, outside the receding surface21, the colored resin layer2looks to have an intermediate color and brightness of the gradation. Therefore, the same effects also can be obtained in Embodiment 2 as in Embodiment 1.

Modification

Although the front surface2bof the resin layer2is a flat surface in Embodiments 1 and 2, the front surface2bof the resin layer2may be bowed or may be formed with an undulation, for example. Moreover, the reference surface22of the back surface2aof the resin layer2does not necessarily have to be a flat surface perpendicular to the thickness direction of the resin layer2. For example, in the case where the front surface2bis bowed, the reference surface22may be a bowed surface parallel to the front surface2b.

Alternatively, like a modified decorative member1C shown inFIGS. 6A and 6B, the receding surface21may be formed over the entire back surface2aof the resin layer2. However, with the reference surface22being provided outside the receding surface21as in Embodiments 1 and 2, the darkness at an edge of the receding surface21is accentuated in comparison with the reference surface22and a higher three-dimensional visual effect can be obtained.

Furthermore, the receding surface21does not necessarily have to be a concave surface forming a depression that opens while broadening. As shown inFIG. 6B, the receding surface21may have a cross-sectional shape that extends from one end to the other end so as to only come closer to the front surface2b, in the direction in which the receding surface21is curved.

Moreover, the receding surface21does not necessarily have to be curved along at least one direction perpendicular to the thickness direction of the resin layer2so as to be convex toward the front surface2b. For example, like a modified decorative member1D shown inFIG. 7, the receding surface21may be inclined linearly toward the front surface2b. However, with the cross-sectional shape of the receding surface21being a curved line as in Embodiments 1 and 2, the degree of the gradation formed on the convex portion of the reflective layer3varies in accordance with the angle at which the decorative member1A is viewed, and thereby the three-dimensional visual effect can be accentuated further.

The decorative member according to the present invention does not necessarily have to have a shape extending in a specified direction. For example, it may have a regular polygonal shape in a plan view, or a rectangular frame shape that opens in the thickness direction of the resin layer2.

EXAMPLES

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not restricted to these Examples.

Example

A resin layer with shaped as shown inFIGS. 5A and 5Bwas molded by injection molding using an acrylic resin (ACRYLITE produced by Mitsubishi Rayon Co., Ltd., color tone No. 530 blue smoke). From the viewpoint of mechanical strength and moldability, the thickness of the thinnest portion defined by the bottom of the receding surface21was set to 1.0 mm, and the thickness of the thickest portion defined by the reference surface22was set to 2.0 mm. In the back surface of this resin layer, dots with a diameter of 10 μm were formed on the receding surface by gravure printing using a black ink so that the density of the dots changes gradually from 0 dots/mm2to 19000 dots/mm2from the bottom of the receding surface to the peripheral portion of the receding surface, and the ink was printed on the entire reference surface. Thus, a pigmented layer was formed. Thereafter, a coating material containing a metallic pigment (SUPER BRIGHT SILVER 2000, produced by Dai Nippon Toryo Co., Ltd.) was applied on the pigmented layer to form a coating film serving as the reflective layer. Thereby, a decorative member was obtained.

Comparative Example 1

A decorative member was obtained in the same manner as in Example, except that the thickness of the thickest portion of the resin layer was set to 3.0 mm and no pigmented layer was formed.

Comparative Example 2

A decorative member was obtained in the same manner as in the Example, except that no pigmented layer was formed.

The decorative members of Example and Comparative Examples were measured for bright/dark ratio. The measurement of the bright/dark ratio was made by measuring the reflectances of the thinnest portion and the thickest portion in increments of 10 nm in the wavelength range of 400 nm to 740 nm with a spectrophotometer (CM-3600d, manufactured by Konica Minolta Holdings, Inc.), and calculating the ratio between the averages thereof. Table 1 shows the results.

In Comparative Example 1, the level difference in the receding surface formed in the back surface of the resin layer is large and a high three-dimensional visual effect can be obtained. However, the large level difference in the receding surface causes warpage and weld to occur, decreasing the yield at the time of molding the resin layer. In Comparative Example 2, the yield at the time of molding the resin layer is less decreased because the level difference in the receding surface is small, but the bright/dark ratio is lowered significantly in comparison with Comparative Example 1, deteriorating the three-dimensional visual effect significantly.

In contrast, in Example, even with the small level difference in the receding surface, it is possible to keep the bright/dark ratio comparable to that of Comparative Example 1 and to obtain a high three-dimensional visual effect.

INDUSTRIAL APPLICABILITY

The present invention is useful for decorative members to be used for providing high quality decoration to casings of electrical devices, etc.