WO2023084705A1 - Resin molded article - Google Patents

Abstract

If a coating film on the surface of an embossed base material is chipped off or the background of the base material is exposed, the figure of the entire surface gives a product a well-worn appearance as if the product has been used for a long time.　A resin molded article according to the present invention is obtained by molding a base material that is formed of a resin; and the base material has an embossed relief surface that is covered with a coating material. The thickness of the coating film of the coating material in a recessed part of the relief surface is larger than the thickness of the coating film of the coating material in a projected part of the relief surface.

Description

Resin molded product

The present invention relates to resin molded products.

Texturing is a type of surface treatment method for base materials such as resins and metals that are used to mold industrial products. Graining is used to create a sense of luxury and beauty in the appearance of industrial products. It is desirable that texture-finished industrial products do not appear to have a feeling of use even if the industrial products are used continuously, and that the appearance of the texture finish is maintained indefinitely to maintain the same state as a new product. Therefore, when the textured surface of the base material is coated with paint, the thickness of the coating film is set thin so as not to impair the textured appearance. In industrial products that are required to be maintained in a state similar to new, the shape of the uneven surface and the thickness of the coating film are set on the premise that the coating film will not peel off.

So far, there have been proposals related to texture processing and coating films (see Patent Documents 1 to 3, for example).

Japanese Patent Publication No. 6-55294 Patent No. 6456335 Patent No. 6431351

In the present invention, when part of the coating film of the paint covering the textured uneven surface of the base material for molding the product is peeled off, the morphology (color, pattern, etc.) of the entire uneven surface is changed so that the product can be used continuously. To provide a resin-molded article that appears in the appearance of the product as a production of feeling of use.

The resin molded product according to the present invention is a resin molded product obtained by molding a base material made of resin, the base material having an uneven surface subjected to texturing, the uneven surface being coated with a paint, and the uneven surface The thickness of the coating film of the coating material on the recesses is larger than the thickness of the coating film of the coating material on the projections of the uneven surface.

In the present invention, when a part of the coating film of the paint covering the textured uneven surface of the base material for molding the product is peeled off, the shape of the entire uneven surface changes to produce a feeling of use due to continued use of the product. Appears in the appearance of the product as

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows embodiment of the resin molding which concerns on this invention. It is a schematic sectional view of the said base material which shows the shape of the surface of the base material which shape|molds the said resin molded product. It is a reference drawing which shows the name of each part of the said surface. Fig. 3 is a schematic cross-sectional view of the base material showing a coating film of a paint coating the surface. It is a reference drawing which shows the depth of the uneven|corrugated|grooved part of the said surface. It is a reference drawing which shows the thickness of the said coating film in the convex part of the said surface. It is a reference drawing which shows the thickness of the said coating film in the recessed part of the said surface. FIG. 4 is a schematic cross-sectional view of the substrate showing a state in which the coating film has been peeled off from the protrusions on the surface. FIG. 4 is a schematic cross-sectional view of the substrate showing a state in which the coating film on the projections on the surface is peeled off and the surface of the substrate is exposed. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows relationship (1) between (a) surface morphology of the resin molding which concerns on this invention, and (b) the wear condition of the uneven surface of a base material. FIG. 2 is a schematic diagram showing the relationship (2) between (a) the shape of the surface of the resin molded article according to the present invention and (b) the state of wear of the uneven surface of the substrate. FIG. 3 is a schematic diagram showing the relationship (3) between (a) the surface morphology and (b) the wear state of the uneven surface of the base material of the resin molded product according to the present invention. It is a schematic diagram which shows the relationship (1) between (a) surface morphology of the conventional resin molding, and (b) the wear condition of the uneven surface of a base material. It is a schematic diagram which shows the relationship (2) of the conventional resin molding product (a) surface form, and (b) the wear condition of the uneven surface of a base material. It is a schematic diagram which shows the relationship (3) of the conventional resin molding product (a) surface form, and (b) the wear condition of the uneven surface of a base material. It is a graph which shows the measurement result of the roughness measurement of the surface of the resin molding which concerns on this invention. It is an electron microscope photograph which image|photographed the said surface when implementing the abrasion test (1) of the surface of the resin molding which concerns on this invention. FIG. 11 is another electron micrograph of the surface of the resin molded article according to the present invention when the wear test (part 2) of the surface was carried out. FIG.

●Resin molded products●
An embodiment of a resin molded product according to the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of a resin molded product (hereinafter referred to as "this product") according to the present invention.
In this embodiment, the product is the housing of the smartphone 1 . This product is, for example, the part of the exterior of a smartphone other than the touch panel display, which is held by the user's hand.

It should be noted that this product is not limited to smartphone housings, and may be smartphone cases or other industrial products.

FIG. 2 is a schematic cross-sectional view of the substrate 2 showing the shape of the surface of the substrate 2 on which the product is molded.
The base material 2 is made of resin, for example. The type of resin is, for example, polycarbonate. The figure shows that the substrate 2 has an uneven surface 2S. The uneven surface 2</b>S is formed by texturing the surface of the base material 2 . The texturing is performed, for example, by using a mold for manufacturing a housing in which an uneven pattern is formed by etching using the action of a chemical agent. A base material (resin or the like) to be processed by this mold has an uneven surface transferred from the mold. As a result, the base material on which the product is molded has a textured surface.

FIG. 3 is a reference diagram showing the name of each part of the uneven surface 2S.
The concave-convex surface 2S is configured by alternately arranging concave portions C and convex portions V. As shown in FIG. The highest point of each convex portion V (upper end of the convex portion V on the paper surface of the figure) is the vertex VT of each convex portion V. FIG. The lowest point of each recess C (lower end of the recess C on the paper surface of the drawing) is the bottom point CB of each recess C. As shown in FIG.

FIG. 4 is a schematic cross-sectional view of the substrate 2 showing the paint film 3 covering the uneven surface 2S.
The figure shows that the concave portion C and the convex portion V of the concave-convex surface 2S are coated with paint. The paint is a known paint, for example a matte color paint.

The figure shows that, in the entire uneven surface 2S, the height of the coating film 3 of the paint covering the uneven surface 2S (the position in the vertical direction of the paper surface of the figure) is the highest at the vertex VT of each convex portion V. show. In the figure, the height of the vertex VT of each convex portion V (the position in the vertical direction of the paper surface of the same figure) is greater than the height of the surface 3S of the coating film 3 in each concave portion C (the position in the vertical direction of the paper surface of the same figure). is also high, indicating that

FIG. 5 is a reference diagram showing the depths of adjacent concave and convex portions (concave portion C and convex portion V (see FIG. 3)).
As shown in the figure, the depth of the adjacent irregularities (the length in the up-down direction of the paper surface of the figure) is represented by D1.

FIG. 6 is a reference diagram showing the thickness of the coating film 3 at the vertex VT (see FIG. 3) of the convex portion V. As shown in FIG.
As shown in the figure, the thickness of the coating film 3 at the vertex VT of the convex portion V (the length in the vertical direction of the paper surface of the figure) is represented by D2.

FIG. 7 is a reference diagram showing the thickness of the coating film 3 at the bottom point CB of the recess C (see FIG. 3).
As shown in the figure, the thickness of the coating film 3 at the bottom point CB of the concave portion C (the length in the vertical direction of the paper surface of the figure) is represented by D3.

Here, the depth D1 of the adjacent uneven portion and the thickness D3 of the coating film 3 at the bottom point CB of the concave portion C are determined when the convex portion V is worn and the surface of the substrate 2 is exposed. The size is set so that the coating film of the paint 3 in the concave portion C adjacent to the convex portion V does not peel off.

Also, the thickness D3 of the paint film 3 at the bottom point CB of the concave portion C is set larger than the thickness D2 of the paint film 3 at the top portion VT of the convex portion V.

Furthermore, there is no regularity in the period of the distance between adjacent concave portions C and convex portions V on the uneven surface 2S. There is also no regularity in the period of the depth between adjacent concave portions C and convex portions V on the uneven surface 2S.

Therefore, as will be described later, when the base material 2 is exposed at a plurality of positions on the uneven surface 2S, there is no positional regularity between the plurality of exposed positions.

The thickness D2 of the coating film 3 at the vertex VT of the convex portion V is the thickness of the vertex VT when the product is used for a predetermined period (when the number of times of friction received by the product reaches a predetermined number). It is set so that the surrounding coating film is peeled off.

In this way, the uneven shape of the uneven surface 2S is set so that the inclination angle of the slope from the apex VT of the convex portion V to the bottom point CB of the concave portion C is steep in the adjacent uneven portions. As a result, the paint applied to the uneven surface 2S forms a thin coating 3 around the vertices VT of the projections V. As shown in FIG. On the other hand, the paint applied around the vertex VT of the convex portion V flows toward the CB of the concave portion C and accumulates in the concave portion C to form a coating film 3 . However, the thickness of the coating film 3 in the concave portion C is set to such a thickness that the coating film in the concave portion C does not peel off even if the periphery of the vertex VT of the convex portion V wears.

The average value of the depths D1 of adjacent irregularities in the entire irregular surface 2S is, for example, 80 microns.
The average value of the thickness D2 of the coating film 3 at each vertex VT of the convex portion V on the entire uneven surface 2S is, for example, 6 microns.
The average value of the thickness D3 of the coating film 3 at each of the bottom points CB of the recesses C over the entire uneven surface 2S is 30 microns.

FIG. 8 is a schematic cross-sectional view of the base material 2 showing a state in which the coating film 3 has been peeled off from the protrusions V. As shown in FIG.
The figure shows a state in which the coating film 3 is peeled off at the location indicated by symbol P1, and the convex portion V is not coated with the coating. The cause of peeling of the coating film 3 is, for example, friction between the hand of the user using the smartphone 1 and the product, or friction between the product and the fabric when the product is put in the pocket of the pants. Due to friction, friction between this product and the desk, etc. when placed on the desk, etc.

As described above, the height of the paint film 3 covering the uneven surface 2S (position on the upper side of the paper surface of FIG. 4) is the highest at the vertex VT of the convex portion V of the uneven surface 2S. Therefore, on the uneven surface 2S, the places where the coating film 3 is most likely to peel off due to friction between the product and the user's hand, etc., are around the vertexes VT of the convex portions V of the uneven surface 2S.

FIG. 9 is a schematic cross-sectional view of the base material 2 showing a state in which the coating film 3 has peeled off from the protrusions V and the surface of the base material 2 is exposed.
The figure shows a state in which the coating film 3 at the location indicated by symbol P2 has been peeled off, and the periphery of the apex VT of the convex portion V of the uneven surface 2S has been worn due to friction with the location. The surface 2T of the substrate 2 is exposed due to wear around the vertex VT.

As described above, the height of the vertex VT of the convex portion V of the uneven surface 2S is higher than the height of the surface 3S of the coating film 3 in the concave portion C. Even if the periphery of the vertex VT of the projection V of the uneven surface 2S is worn, the coating film 3 in the recess C of the uneven surface 2S is not worn.

Here, the color of the background of the base material 2 is selected, for example, so that the glossiness of the color of the worn background is higher than the glossiness of the color of the paint. That is, the color of the paint and the color of the background are the area where the coating film 3 is not peeled off, the area where the coating film 3 is peeled off, and the area where the background of the substrate 2 is exposed on the uneven surface 2S. The color is toned so that a gradation of color density occurs between

●Relationship between the surface morphology of this product and the state of wear of the uneven surface of the base material●
10 to 12 are schematic diagrams showing the relationship between the surface morphology of the product and the wear state of the uneven surface of the substrate.

FIG. 10 is a schematic diagram of (a) the shape of the surface of the product, and (b) a cross-sectional view taken along the line AA of (a).
As shown in (b) of the same figure, the same figure shows a state in which the coating film of the coating material covering the uneven surface of the base material is not peeled off. As described above, on the entire uneven surface of the base material of the present product, the inclination angle of the slope connecting the protrusions and recesses of the adjacent protrusions and recesses is set steeply. Therefore, the thickness of the coating film on the convex portions is thinner than the thickness of the coating film on the concave portions. Also, the periodicity of the distances between adjacent recesses and protrusions is not regular. Furthermore, the period of the height of each convex portion does not have regularity. As a result, as shown in (a) of the figure, the surface of the uneven surface has an irregular area L1 where the color of the paint appears and an area L2 where the color of the base material appears through the coating film. Arranged by position and size.

FIG. 11 is a schematic diagram of (a) showing the shape of the surface of the product, and (b) showing a cross-sectional view taken along the line AA of (a).
As shown in (b) of the figure, the figure shows a state in which the coating film of the paint on the convex portions of the uneven surface of the base material is peeled off, exposing the background of the base material. That is, the uneven surface includes a region L1 around the concave portion where the coating film is thick, a region L2 around the convex portion where the coating film is thin, a region L3 around the convex portion where the paint is worn, and the surface of the base material is exposed. and a region L4 of the convex portion. Here, the color of the paint and the color of the background of the base material are toned so that a gradation of color density occurs between the regions L1, L2, L3, and L4 (for example, in descending order of color glossiness). The colors are toned to be L1, L2, L3, and L4. As a result, as shown in FIG. 4A, an area L3 where the color of the worn and polished paint appears is arranged around the area L4 where the color of the base material appears. A region L2 in which the color of the base material appears through the coating film is arranged around the region L3. In other regions of the uneven surface, L1 is arranged in which the color of the paint appears.

FIG. 12 is a schematic diagram of (a) showing the shape of the surface of the product, and (b) showing a cross-sectional view taken along the line AA of (a).
As shown in (b) of the same figure, in FIG. 12, peeling of the coating film of the paint on the convex portions and exposure of the background of the base material progressed compared to the state of the uneven surface shown in FIG. Indicates status. In (a) of FIG. 11, the size of a region L4 where the color of the base material appears and the size of a region L3 where the color of the worn and polished paint appears are larger than in the state shown in FIG. indicate that

In this way, with this product, when the coating film on the uneven surface peels off, different colors appear in areas of irregular positions and sizes on the entire uneven surface. appear in the appearance of this product.

●Relationship between the surface morphology of conventional resin molded products and the state of wear of the uneven surface of the base material●
13 to 15 are schematic diagrams showing the relationship between the surface morphology of a conventional resin molded product (hereinafter referred to as "conventional product") and the state of wear of the uneven surface of the substrate.

FIG. 13 is a schematic diagram of (a) showing the shape of the surface of a conventional product, and (b) showing a cross-sectional view taken along the line AA of (a).
As shown in (b) of the same figure, the same figure shows a state in which the coating film of the coating material covering the uneven surface of the base material is not peeled off. (b) of the figure shows that the distances between the adjacent recesses and protrusions are equal and the heights of the protrusions are substantially the same on the uneven surface of the conventional product. (b) of the figure shows that the surface of the conventional product is coated with a coating film of uniform thickness over the entire surface. As a result, as shown in (a) of the figure, almost the entire surface of the uneven surface is a region M1 where the color of the paint appears, and a region M2 where the color of the base material appears through the coating film is the uneven surface. It is part.

FIG. 14 is a schematic diagram of (a) showing the shape of the surface of a conventional product, and (b) showing a cross-sectional view taken along the line AA of (a).
As shown in (b) of the figure, the figure shows a state in which the coating film covering the uneven surface of the base material is almost evenly peeled off over the entire uneven surface. That is, the height position of the uneven surface (the length in the up-down direction of the drawing) is substantially the same over the entire uneven surface. As a result, as shown in (a) of the same figure, almost the entire surface of the uneven surface is a region M3 where the background color of the base material appears through the thin coating film, and the base material is transparent through the coating film. A region M2 in which the color of appears is part of the uneven surface.

FIG. 15 is a schematic diagram of (a) showing the shape of the surface of a conventional product, and (b) showing a cross-sectional view taken along the line AA of (a).
As shown in (b) of the figure, in FIG. 15, the peeling of the coating film of the paint progresses more than the state of the uneven surface shown in FIG. indicates that the As a result, as shown in (a) of the same figure, almost the entire surface of the uneven surface is a region M5 where the color of the background of the substrate appears, and the color of the background of the substrate appears through the thin coating film. The region M4 with the ridge is a part of the uneven surface.

In this way, compared to the uneven surface of the conventional product, the slope angle between the adjacent concave and convex portions is not steep, and the entire surface of the uneven surface is coated with a uniform thickness. covered with a membrane. Therefore, when the uneven surface of the conventional product is rubbed, the coating film peels off uniformly over the entire surface of the uneven surface, and the same color appears over the entire surface. As a result, when the coating film on the uneven surface peels off, the conventional product does not produce gradation of color density in irregular positions and sizes like this product, and the surface where the coating film has peeled off uniformly does not occur. Some of them look like damaged areas.

●Example●
The following is an example using a smart phone housing (polycarbonate resin coated with UV curable paint) manufactured by the applicant of the present application.

●Measurement of Surface Roughness The following are the results of measuring the surface roughness of the housing of the smartphone manufactured by the applicant of the present application before painting.

Evaluation conditions and the like are as follows.
Evaluation device: SURFTEST SJ-310 (Mitutoyo Corporation)
Standard: JIS1982
Curve: P
Filter: NONE
Arbitrary length: 12.50mm
Input: NONE
Forward run/backward run: OFF
Waveform deletion: OFF
Pass/fail judgment: Average value

FIG. 16 is a graph showing measurement results of the surface of the housing before painting.
The horizontal axis in the figure indicates the surface direction of the uneven surface of the housing (corresponding to the horizontal direction on the paper surface of FIG. 2). The vertical axis in the figure indicates the uneven direction of the uneven surface of the housing (corresponding to the vertical direction on the page of FIG. 2). In the figure, the horizontal axis is magnified 10 times and the vertical axis is magnified 200 times.
The figure shows the distance between adjacent recesses and protrusions, the height position of the bottom point of each recess (the position in the vertical direction of the paper surface of FIG. 16), and the height of the apex of each protrusion on the entire uneven surface. The position (the position in the vertical direction of the paper surface of FIG. 16) and are irregular. That is, in the same figure, there is no regularity in the period of the distance between the adjacent concave portions C and the convex portions V on the uneven surface 2S, and the period of the depth between the adjacent concave portions C and the convex portions V shows that there is no regularity in

Abrasion Test The following are the results of an abrasion test using an RCA abrasion tester on the surface of the housing of the smartphone manufactured by the applicant of the present application.

The test conditions are as follows.
・Abrasion times: 200 times ・Pressure: about 1.7N
・Rotation speed: 150rpm

FIG. 17 is an electron micrograph of the surface after abrasion testing (10 RCAs) on the surface of the housing.
The whitish spots in the area surrounded by the dashed lines in the figure are the spots where the paint film has peeled off. The figure shows that the peeled portions of the coating film are not uniformly present over the entire surface, but are irregularly present over the entire surface.

FIG. 18 is an electron micrograph of the surface after the abrasion test (20 times RCA) on the surface of the housing.
A whitish portion within the region surrounded by the dashed line in the figure is a portion where the coating film of the paint has peeled off and the surface of the substrate is exposed. The figure shows that the exposed portions of the base material are not uniformly distributed over the entire surface, but are irregularly distributed over the entire surface. That is, this figure shows that when the base material is exposed at a plurality of positions on the uneven surface, there is no positional regularity between the plurality of exposed positions.

●Summary●
According to the embodiment described above, in this product, the thickness of the coating film 3 of the paint on the concave portions C of the uneven surface 2S is greater than the thickness of the coating film of paint on the convex portions V of the uneven surface 2S. Therefore, when part of the coating film 3 covering the textured uneven surface 2S of the base material 2 is peeled off, or when the background of the base material 2 is exposed, irregular positions and sizes of the entire uneven surface 2S may occur. A gradation of shades of color appears in the area of lowness. In other words, the shape of the uneven surface 2S as a whole, in which irregular positions and sizes appear, appears in the appearance of the product as a presentation of the usability of the product as a result of continued use of the product.

1 resin molded article 2 base material 2S surface of base material (uneven surface)
2T Substrate texture C Concave recesses on substrate uneven surface CB Bottom point of recesses on substrate uneven surface V Protrusions on substrate uneven surface VT Vertex of protrusions on substrate uneven surface 3 Coating film 3S Coating film D1 Depth of the adjacent uneven surface D2 Thickness of the coating film at the peak of the convex D3 Thickness of the coating film at the bottom of the concave

Claims (7)

A resin molded product obtained by molding a base material made of resin,
The base material has an uneven surface with texturing,
The uneven surface is coated with paint,
The thickness of the coating of the paint in the recesses of the uneven surface is greater than the thickness of the coating of the paint in the protrusions of the uneven surface,
A resin molded product characterized by: The depth of the uneven surface is set to such a depth that the coating film of the paint in the recesses adjacent to the protrusions does not peel off when the protrusions are worn to expose the surface of the base material. ,
The resin molded article according to claim 1. There is no regularity in the period of the distance between the recesses and the protrusions on the uneven surface,
There is no regularity in the depth cycle between the adjacent recesses and protrusions on the uneven surface,
The resin molded article according to claim 2. When the surface of the base material is exposed at a plurality of positions on the uneven surface, there is no regularity between each of the exposed positions.
The resin molded article according to claim 3 When the exposed skin is worn,
The glossiness of the color of the paint is lower than the glossiness of the color of the worn background,
The resin molded article according to claim 4. The color of the paint and the color of the background are the areas on the uneven surface where the coating film of the paint is not peeled off, the area where the coating film of the paint is peeled off, and the background of the base material are exposed. is toned so that a gradation of color intensity occurs between the area where the
The resin molded article according to claim 5. The average depth of the uneven surface is 80 microns,
The average value of the thickness of the coating film in each of the plurality of concave portions of the uneven surface is 30 microns,
The average value of the thickness of the coating film on each of the plurality of convex portions of the uneven surface is 6 microns.
The resin molded article according to claim 1.

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