RESIN MOLDING AND MANUFACTURING METHOD THEREFOR

Abstract

Regarding a resin molding including embossment 4 provided for an interface between a base 2 and a translucent surface layer 3, if a value Y-highlight designates a value Y of light which is incident at 45 degrees and detected at an acceptance angle of +30 degrees, and a value Y-shade designates a value Y of light which is incident at 45 degrees and detected at an acceptance angle of 30 degrees, the value Y-highlight and the value Y-shade being calibrated with a value Y of a white reflectance standard of an XYZ colorimetric system regarded as 100%, a difference between the value Y-highlight and the value Y-shade of a flat portion of a surface of the base material 2 is 5 or more, and the surface layer 3 has a total light transmittance of 2.5% or more and 60% or less.

Claims

1. A resin molding comprising: a base material; and a translucent surface layer which covers a surface of the base material, wherein embossment is provided for an interface between the base material and the surface layer, if a value Y-highlight designates a value Y of light which is incident at 45 degrees and detected at an acceptance angle of +30 degrees, and a value Y-shade designates a value Y of light which is incident at 45 degrees and detected at an acceptance angle of 30 degrees, the value Y-highlight and the value Y-shade being calibrated with a value Y of a white reflectance standard of an XYZ colorimetric system regarded as 100%, a difference between the value Y-highlight and the value Y-shade of a flat portion of the surface of the base material is 5 or more, and the surface layer has a total light transmittance of 2.5% or more and 60% or less.

2. The resin molding of claim 1, wherein the embossment has an emboss height of 5 m or more and 700 m or less.

3. The resin molding of claim 1, wherein the surface layer has a thickness of 0.8 mm or more and 8 mm or less.

4. The resin molding of claim 1, wherein the surface layer contains a coloring agent.

5. The resin molding of claim 1, wherein the difference between the value Y-highlight and the value Y-shade is 10 or more.

6. The resin molding of claim 1, wherein the surface layer has a total light transmittance of 5% or more and 50% or less.

7. A method for manufacturing the resin molding of claim 1, the method comprising: injecting a first resin material in a first molding cavity having a grained molding surface for forming the embossment, thereby forming one of the base material having the embossment corresponding to the grained surface or the surface layer having the embossment corresponding to the grained surface; forming a second molding cavity on a surface of the base material provided with the embossment or a surface of the surface layer provided with the embossment; and injecting a second resin material in the second molding cavity to form the other one of the base material or the surface layer.

8. The method of claim 7, wherein the first resin material contains a brightening material and/or an inorganic pigment, and is injected in the first molding cavity to form the base material having on its surface the embossment corresponding to the grained surface, and the second resin material is injected in the second molding cavity to form the surface layer.

9. The method of claim 8, wherein the surface layer molded from the second resin material has a thickness of 0.8 mm or more and 8 mm or less or less.

10. The method of claim 8, wherein the embossment provided for the surface of the base material has an emboss height of 700 m or less.

11. The resin molding of claim 1, wherein the difference between the value Y-highlight and the value Y-shade is 15 or more and 400 or less.

12. The resin molding of claim 1, wherein the surface layer has a total light transmittance of 8% or more and 40% or less.

13. The resin molding of claim 8, wherein the embossment provided for the surface of the base material has an emboss height of 5 m or more and 700 m or less.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 is a perspective view illustrating a resin molding, partially in cross section.

[0027] FIG. 2 is a cross-sectional view schematically illustrating an example of an injection molding machine used for manufacturing the resin molding.

[0028] FIG. 3 illustrates how a value Y is measured.

[0029] FIG. 4 is a graph illustrating the value Y of a black base material with respect to an acceptance angle.

[0030] FIG. 5 is a graph illustrating the value Y of a white base material with respect to an acceptance angle.

[0031] FIG. 6 is a graph illustrating the value Y of a silver base material with respect to an acceptance angle.

[0032] FIG. 7 is a graph illustrating the value Y of a gunmetal base material with respect to an acceptance angle.

[0033] FIG. 8 is an image (photograph) of embossment seen through a surface layer of Sample 1 (base material: black, a difference between a value Y-highlight and a value Y-shade: 3.7).

[0034] FIG. 9 is an image (photograph) of embossment seen through a surface layer of Sample 2 (base material: white, a difference between the values Y-highlight and Y-shade: 3.7).

[0035] FIG. 10 is an image (photograph) of embossment seen through a surface layer of Sample 3 (base material: silver, a difference between the values Y-highlight and Y-shade: 175).

[0036] FIG. 11 is a graph illustrating spectral reflectance of Sample 1 (with a surface layer).

[0037] FIG. 12 is a graph illustrating spectral reflectance of Sample 2 (with a surface layer).

[0038] FIG. 13 is a graph illustrating spectral reflectance of Sample 3 (with a surface layer).

[0039] FIG. 14 is a graph illustrating a relationship between a value Y and an acceptance angle of Samples 1-3.

[0040] FIG. 15 is a graph comparing a value Y of a flat surface of a black base material, and a value Y of a woodgrain embossed surface of a black base material.

[0041] FIG. 16 is a graph comparing a value Y of a flat surface of a black base material and a value Y of a mesh embossed surface of a black base material.

[0042] FIG. 17 is a graph comparing a value Y of a flat surface of a white base material and a value Y of a woodgrain embossed surface of a white base material.

[0043] FIG. 18 is a graph comparing a value Y of a flat surface of a white base material and a value Y of a mesh embossed surface of a white base material.

[0044] FIG. 19 is a graph comparing a value Y of a flat surface of a silver base material and a value Y of a woodgrain embossed surface of a silver base material.

[0045] FIG. 20 is a graph comparing a value Y of a flat surface of a silver base material and a value Y of a mesh embossed surface of a silver base material.

DESCRIPTION OF EMBODIMENTS

[0046] Embodiments of the present invention will now be described with reference to the drawings. The following description of preferred embodiments is only an example in nature, and is not intended to limit the scope, applications or use of the present invention.

[0047] A resin molding 1 shown in FIG. 1 has a base material 2, and a surface layer 3 covering a surface of the base material 2. Embossment 4 is provided for an interface between the base material 2 and the surface layer 3. The surface layer 3 is made of a translucent resin material, and thus, allows the embossment 4 at the interface to be seen through the surface layer 3. The base material 2 is made of a resin material containing a brightening material and/or an inorganic pigment. The surface layer 3 is made of a resin material containing a coloring agent or a resin material containing no coloring agent.

[0048] FIG. 2 schematically illustrates an example of an injection molding machine 5 used for manufacturing the resin molding 1. The injection molding machine 5 produces the resin molding 1 by co-injection molding.

[0049] The injection molding machine 5 includes a primary cavity mold 6 for molding the base material 2, a secondary cavity mold 7 for molding the surface layer 3, and a pair of core molds 8 used in common for the cavity molds 6 and 7. The cavity molds 6 and 7 are placed on a base 9 to face each other with the core molds 8 interposed therebetween, and are movable in a direction away from each other (mold opening direction). The paired core molds 8 are supported on a rotary 11 which rotates about a vertical axis, and are positioned at 180 degrees with respect to each other.

[0050] A first injection unit 13 for injecting a first resin material 12 for molding the base material is disposed behind the primary cavity mold 6. A second injection unit 15 for injecting a second resin material 14 for molding the surface layer is disposed behind the secondary cavity mold 7. The injection units 13 and 15 are movable back and forth with respect to the cavity molds 6 and 7.

[0051] The primary cavity mold 6 and one of the core molds 8 form a first molding cavity 16 for molding the base material 2. When the first injection unit 13 moves forward to inject the first resin material 12 in a molten state in the first molding cavity 16, the base material 2 is formed. After the mold is opened, the rotary 11 rotates the pair of core molds 8 180 degrees together with the base material 2, and the mold is closed. Then, a second molding cavity 17 for molding the surface layer 3 is formed between a surface of the base material 2 and the secondary cavity mold 7. When the second injection unit 15 moves forward to inject the second resin material 14 in a molten state in the second molding cavity 17, the surface layer 3 covering the surface of the base material 2 is formed. In a preferred embodiment, a temperature for melting the second resin material is lower than a temperature for melting the first resin material.

[0052] If PC is used as a matrix resin of each of the base material 2 and the surface layer 3, for example, a mold temperature may be set to be about 80 C., and a cylinder temperature of the injection units 13 and 15 may be set to be about 250 C., for example, for injection molding the base material 2 and the surface layer 3.

[0053] A cavity surface 6a of the primary cavity mold 6, on which the surface of the base material is molded, is grained. The grained cavity surface 6a provides the surface of the base material 2 with the embossment 4. When the surface layer 3 covers the surface of the base material 2 having the embossment 4, the resin molding 1 in which the embossment is provided for an interface between the base material 2 and the surface layer 3 is obtained.

<Value Y of Base Material>

[0054] In this embodiment, on a flat portion of the surface of the base material 2 with no embossment 4, a difference between a value Y-highlight and a value Y-shade is 5 or more. The value Y is a value calibrated with a value Y of a white reflectance standard of the XYZ colorimetric system regarded as 100%, and is measured as shown in FIG. 3. Light from a light source 21 is incident on the base material 2 at 45 degrees. An acceptance angle of a sensor 22 is measured with respect to a vertical direction (this direction will be hereinafter referred to as face) regarded as 0 degree. The value Y-highlight is a value Y of reflected light measured at an acceptance angle of +30 degrees, and the value Y-shade is a value Y of reflected light measured at an acceptance angle of 30 degrees.

[0055] Test pieces of various base materials (black, white, silver, and gunmetal) containing different coloring agents (a pigment or an inorganic pigment) were prepared, and their values Y were measured. For the measurement, a gonio-spectrophotometric color measurement system GCMS-4 manufactured by Murakami Color Research Laboratory Co., Ltd. was used. FIGS. 4-7 are graphs illustrating the measurement results (values Y that vary depending on the acceptance angle).

[0056] The black base material shown in FIG. 4 contained carbon (concentration: 3 parts) as the coloring agent. The white base material shown in FIG. 5 contained a white pigment (concentration: 3 parts) as the coloring agent. The silver base material shown in FIG. 6 contained aluminum flakes (concentration: 3 parts) as the coloring agent. The gunmetal base material shown in FIG. 7 contained aluminum flakes (concentration: 1 part) and a gunmetal pigment (concentration: 0.5 part) as the coloring agents. PC was used as a matrix resin of each base material. The concentration of each coloring agent is represented in mass ratio relative to 100 parts of the matrix resin.

[0057] Table 1 shows a value Y-face (a value Y of light reflected from the flat portion and measured at an acceptance angle of 0 degree), and a difference between the value Y-highlight and the value Y-shade of each of the four base materials.

TABLE-US-00001 TABLE 1 Base material Black White Silver Gunmetal Difference between value 3.7 3.7 175 21.8 Y-highlight and value Y-shade Value Y-face 0.16 81 20 2.43

<Evaluation of Resin Molding>

[0058] Samples 1-8 of the resin molding shown in Table 2 were prepared. Each of Samples 1-8 adopted one of the black, white, silver, or gunmetal base material shown in Table 1, and a red surface layer having a total light transmittance according to JIS K 7361 of 10% or 15%, or a colorless (containing no coloring agent) surface layer having a total light transmittance of 88%. PC was used as a matrix resin of each of the surface layers. The total light transmittance of the surface layer was measured using Haze Meter NDH2000 manufactured by NIPPON DENSHOKU.

[0059] In each sample, the embossment at the interface was woodgrain with an emboss height of 55 m, and the surface layer had a thickness of 15 mm. Each resin molding was visually evaluated on four scales (A: great, B: less great, C: poor, and D: almost zero) in terms of a color depth, shading, and a spatial depth (three-dimensional look). Table 2 shows the results.

TABLE-US-00002 TABLE 2 Resin molding Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Sample 7 Sample 8 Hue of surface layer Red Red Red Red Red Colorless Colorless Colorless Total light transmittance of surface layer 15% 15% 15% 15% 10% 88% 88% 88% Hue of base material Black White Silver Gunmetal Silver Black White Silver Difference between value Y-highlight and 3.7 3.7 175 21.8 175 3.7 3.7 175 value Y-shade of base material Value Y-face of base material 0.16 81 20 2.43 20 0.16 81 20 Color depth D C B A A D D D Shading D D A B A D D D Spatial depth D C A B A D C B A: great, B: less great, C: poor, D: almost zero

[0060] FIG. 8 is an image of the embossment seen through the surface layer of Sample 1 (base material: black, a difference between the values Y of the base material (value Y-highlightvalue Y-shade): 3.7). The color depth, the shading, and the spatial depth (three-dimensional look) were hardly observed. FIG. 9 is an image of the embossment seen through the surface layer of Sample 2 (base material: white. the difference between the values Y of the base material: 3.7). The color depth and the spatial depth (three-dimensional look) were poor, and the shading was hardly observed. FIG. 10 is an image of the embossment seen through the surface layer of Sample 3 (base material: silver, the difference between the values Y of the base material: 175). The image shows that the color depth, the shading, and the spatial depth (three-dimensional look) were great.

[0061] FIGS. 11-13 illustrate spectral reflectance of each of Samples 1-3 (with a surface layer). Regarding Sample 1, reflectances in a highlight direction (incident angle: 45 degrees, acceptance angle: +30 degrees), a shade direction (incident angle: 45 degrees, acceptance angle: 30 degrees), and a face direction (incident angle: 45 degrees, acceptance angle: 0 degree) were almost zero over the entire visible light range (390 to 730 nm). Sample 2 showed the reflectances in the highlight, shade, and face directions risen in a range from around 580 nm to red wavelengths, but they were low.

[0062] In contrast, Sample 3 showed the reflectances in the shade and face directions risen in a range from around 580 nm to the red wavelengths, but the rise was low. On the other hand, the reflectance in the highlight direction showed a great rise in the red wavelengths, indicating that the color depth and the shading were great. The difference between the reflectance in the highlight direction and the reflectance in the face direction, and the difference between the reflectance in the highlight direction and the reflectance in the shade direction at a wavelength of 690 nm were within a range from 30% or more to 60% or less.

[0063] The reflectances in the highlight, shade, and face directions were calibrated with a reflectance of a white reflectance standard regarded as 100%, and measured using gonio-spectrophotometric color measurement system GCMS-4 manufactured by Murakami Color Research Laboratory Co., Ltd.

[0064] FIG. 14 illustrates a relationship between the acceptance angle and a value Y (not of the flat portion of the surface of the base material, but of the resin molding) of each of Samples 1-3. Regarding Samples 1 and 2, the values Y-highlight, Y-shade, and Y-face were almost equal. In Sample 3, the value Y increased in the order of the values Y-shade, Y-face, and Y-highlight, i.e., the value Y measured closer to the regular reflection direction was greater. Regarding Sample 3, the difference between the value Y-highlight and the value Y-face was in a range from 6 or more to 10 or less. The difference between the value Y-face and the value Y-shade was in a range from 0.5 or more to 1.5 or less. The values Y were measured using a gonio-spectrophotometric color measurement system GCMS-4 manufactured by Murakami Color Research Laboratory Co., Ltd.

[0065] FIGS. 15-20 are graphs each showing the results of comparison between the value Y of a base material with a flat surface and the value Y of a base material with an embossed surface. The comparison is carried out to examine the influence of the difference in hue (black, white, and silver) and the difference in embossment (woodgrain (emboss height: 55 m) and mesh (emboss height: 118 m) on the value Y of the base material. The values Y were measured using a 2D luminance colorimeter UA-200 of Topcon Technohouse Corporation. A unit of the horizontal axis of each of the graphs of FIGS. 15-20 is a pixel.

[0066] As shown in FIGS. 15 and 16, when the hue was black, the difference in value Y between the flat base material and the embossed base material was small, irrespective of whether the embossment was woodgrain or mesh. This indicates that, in this case, the embossment was not greatly emphasized when observed through the surface layer.

[0067] As shown in FIGS. 17 and 18, when the hue was white, the difference in value Y between the flat base material and the embossed base material became greater, but the amplitude of the value Y caused by the embossment did not greatly increase, as compared with the case where the hue was black. This indicates that the embossment was not greatly emphasized when observed through the surface layer.

[0068] In contrast, as shown in FIGS. 19 and 20, when the hue was silver, the difference in value Y between the flat base material and the embossed base material increased (difference between mean values of the values Y was 50 or more), and the amplitude of the value Y caused by the embossment also increased. This indicates that the embossment was emphasized when observed through the surface layer.

DESCRIPTION OF REFERENCE CHARACTERS

[0069] 1 Resin Molding [0070] 2 Base Material [0071] 3 Surface layer [0072] 4 Embossment [0073] 5 Injection Molding Machine [0074] 6 Primary Cavity Mold [0075] 7 Secondary Cavity Mold [0076] 8 Core Mold [0077] 12 First Resin Material [0078] 14 Second Resin Material [0079] 16 First Molding Cavity [0080] 17 Second Molding Cavity