Coating film-equipped resin molded article, mold for resin molded article, and mold for coating film

Abstract

Provided is a coating film-equipped resin molded body in which peeling of the coating film is suppressed. This coating film-equipped resin molded article comprises a resin molded article and a coating film which is formed on a surface of the resin molded article, wherein: the resin molded article has a plurality of embossed portions on a surface thereof; said surface has a first average length RSm according to JIS B0601(ISO4287) of not more than 300 μm; and the coating film has a film thickness of 0.01-1 mm.

Description

Resin molded products with paint film, molds for resin molded products, and molds for paint film

[0001] The present disclosure relates to a resin molded product with a paint film, a mold for a resin molded product, and a mold for a paint film, and in particular to the production of a resin molded product with a paint film (in-mold painted molded product) using a mold set for in-mold painting.

[0002] Conventionally, when forming a paint film on a resin molded product, the resin molded product is formed by injection molding in a mold, and the resin molded product is then removed from the mold, and a paint is applied and dried. In contrast to this, an in-mold painting technique is known in which, after forming a resin molded product by injection molding in a mold, the cavity mold is changed and a paint film is formed in the mold (see, for example, Patent Document 1).

[0003] In-mold coating requires a solvent-free coating because the coating film is formed in the enclosed space inside the mold, making it difficult to ensure stable adhesion to the molded resin product. Also, due to the high transferability of the coating material, the coating may stick to the mold cavity during demolding, causing the coating film to peel off from the surface of the molded resin product.

[0004] Japanese Patent Application Laid-Open No. 2002-225075

[0005] In contrast to this, in the above-mentioned Patent Document 1, ozone gas is injected into the painted surface of the primary resin molded product after the primary resin molding to corrode the surface of the primary resin molded product, and then a coating material is injected, thereby improving the adhesion of the coating material.

[0006] However, in the above case, the injection of ozone gas requires equipment such as an ozone generator and a recovery mechanism, which increases the manufacturing cost and also increases the number of steps, resulting in problems such as a longer takt time.

[0007] Therefore, an object of the present disclosure is to provide a resin molded article with a coating film that suppresses peeling of the coating film.

[0008] The resin molded article with a paint film according to the present disclosure is a resin molded article with a paint film, comprising a resin molded article and a paint film formed on the surface of the resin molded article, wherein the resin molded article has a plurality of grains on the surface, the surface has an average length RSm of 300 μm or less in accordance with JIS B0601 (ISO4287), and the paint film has a film thickness of 0.01 mm or more and 1 mm or less.

[0009] The mold for a resin molded product according to the present disclosure is a mold for a resin molded product including a core mold for injection molding the resin molded product and a cavity mold for the resin molded product, wherein the cavity mold for the resin molded product has a plurality of transfer embossments on its surface to be transferred to the surface of the resin molded product, and the first average length RSm of the surface in accordance with JIS B0601 (ISO4287) is 300 μm or less.

[0010] The mold for a paint film according to the present disclosure is a mold for a paint film including a core mold for forming a paint film on the surface of a resin molded product and a cavity mold for a paint film, wherein the cavity mold for a paint film has a plurality of second transfer embossments on its surface for transferring to the surface of the paint film, and the second average length RSm of the surface conforming to JIS B0601 (ISO4287) is 300 μm or less.

[0011] According to the resin molded product with a paint film of the present disclosure, the surface of the resin molded product has multiple grains, and the average length RSm of the surface of the resin molded product is within a predetermined range, thereby providing an anchor effect and suppressing peeling of the paint film.

[0012] 1 is a schematic cross-sectional view showing the cross-sectional structure of a resin molded product with a paint film according to embodiment 1. FIG. 2 is a schematic cross-sectional view showing the cross-sectional structure inside a mold for a resin molded product when forming the resin molded product according to embodiment 1. FIG. 3 is an enlarged cross-sectional view of the surfaces of the resin molded product and the cavity mold for the resin molded product of FIG. 2A. FIG. 4 is a schematic cross-sectional view showing the cross-sectional structures of the cavity mold for a paint film, the resin molded product, and the core mold when forming a paint film on the surface of the resin molded product according to embodiment 1. FIG. 5 is an enlarged cross-sectional view showing the gap between the surface of the resin molded product of FIG. 3A and the surface of the cavity mold for a paint film. FIG. 6 is an enlarged cross-sectional view showing the gap between the surface of the resin molded product of FIG. 3A and the surface of the cavity mold for a paint film in an in-mold coating mold set according to embodiment 2. FIG. 7 is a schematic cross-sectional view showing a state in which paint is injected into the gap between the cavity mold for a paint film and the core mold that constitute the mold for a paint film when forming a paint film on the surface of the resin molded product according to embodiment 1. FIG. 8 is a schematic cross-sectional view showing the cross-sectional structures of the cavity mold for a paint film, the paint film, the resin molded product, and the core mold when forming a paint film on the surface of the resin molded product according to embodiment 1. 5B is an enlarged cross-sectional view showing the cross-sectional structure of the cavity mold for a paint film, the paint film, and the resin molded product of FIG. 5A. FIG. 5C is an enlarged cross-sectional view showing the cross-sectional structure of the cavity mold for a paint film, the paint film, and the resin molded product of FIG. 5A in an in-mold coating mold set according to embodiment 2. FIG. 5D is a schematic cross-sectional view showing the cross-sectional structure of a resin molding mold consisting of a cavity mold for a resin molded product and a core mold when forming an out-mold type resin molded product. FIG. 5E is a schematic cross-sectional view showing the cross-sectional structure of a resin molding mold consisting of a cavity mold for a resin molded product and a core mold when forming a die-slide type resin molded product. FIG. 5F is a schematic cross-sectional view showing the cross-sectional structure of a paint film mold consisting of a cavity mold for a paint film and a core mold when forming a die-slide type resin molded product. FIG. 5G is a partially enlarged cross-sectional view showing the cross-sectional structure of the surface of a resin molded product with a paint film.

[0013] The resin molded article with a coating film according to the first aspect is a resin molded article with a coating film, which comprises a resin molded article and a coating film formed on the surface of the resin molded article, wherein the resin molded article has a plurality of grains on the surface, the surface has a first average length RSm in accordance with JIS B0601 (ISO4287) of 300 μm or less, and the coating film has a film thickness of 0.01 mm or more and 1 mm or less.

[0014] The coated resin molded article according to the second aspect may be the resin molded article according to the first aspect, wherein the surface of the resin molded article has a first ten-point average roughness Rzjis in accordance with JIS B0601 (ISO4287) of 0.5 μm or more and 50 μm or less.

[0015] The resin molded article with a coating film according to a third aspect is the resin molded article according to the first or second aspect, wherein the coating film has a plurality of grains on the surface, and the surface may have a second average length RSm in accordance with JIS B0601 (ISO4287) of 300 μm or less.

[0016] The resin molded article with a coating film according to a fourth aspect may be the third aspect, wherein the surface of the coating film has a second ten-point average roughness Rzjis in accordance with JIS B0601 (ISO4287) of 0.5 μm or more and 50 μm or less.

[0017] The resin molded product with a paint film according to the fifth aspect may be the third or fourth aspect, wherein the plurality of embossments on the surface of the paint film correspond to the surfaces of the resin molded product on which the plurality of embossments are provided.

[0018] A mold for a resin molded product according to a sixth aspect is a mold for a resin molded product including a core mold for injection molding the resin molded product and a cavity mold for the resin molded product, wherein the cavity mold for the resin molded product has a plurality of grains on its surface to be transferred to the surface of the resin molded product, and the first average length RSm of the surface in accordance with JIS B0601 (ISO4287) is 300 μm or less.

[0019] The seventh aspect of the mold for a paint film is a mold for a paint film including a core mold for forming a paint film on the surface of a resin molded product and a cavity mold for a paint film, wherein the cavity mold for a paint film has a plurality of textures on its surface for transferring to the surface of the paint film, and the second average length RSm of the surface conforming to JIS B0601 (ISO4287) is 300 μm or less.

[0020] The mold set for in-mold coating according to the eighth aspect comprises the mold for a resin molded product according to the sixth aspect and the mold for a paint film according to the seventh aspect.

[0021] The in-mold coating mold set according to the ninth aspect may be the same core mold as the core mold for the mold for the resin molded product and the core mold for the mold for the paint film in the eighth aspect.

[0022] The mold set for in-mold coating according to the tenth aspect may be such that, in the eighth or ninth aspect described above, the multiple embossments on the surface of the cavity mold for the paint film of the mold for the paint film may be provided to correspond to the multiple embossments on the surface of the cavity mold for the resin molded product of the mold for the resin molded product.

[0023] The mold set for in-mold coating according to the eleventh aspect may be any of the eighth to tenth aspects above, wherein the cavity mold for a resin molded product of the mold for a resin molded product and the cavity mold for a paint film of the mold for a paint film are arranged so that their positions facing the core mold are interchangeable with each other.

[0024] Hereinafter, a resin molded product with a paint film, a mold for a resin molded product, a mold for a paint film, and a mold set for in-mold coating according to embodiments will be described with reference to the accompanying drawings. Note that substantially identical components in the drawings are given the same reference numerals.

[0025] (Embodiment 1) <Coated Resin Molded Product (In-Mold Coated Molded Product)> FIG. 1 is a schematic cross-sectional view showing the cross-sectional structure of a coated resin molded product (in-mold coated molded product) 20 according to embodiment 1. FIG. 2A is a schematic cross-sectional view showing the cross-sectional structure inside a mold 26 for a resin molded product when forming the resin molded product 10 according to embodiment 1. FIG. 2B is an enlarged cross-sectional view of a circled portion A on the surface of the resin molded product 10 and the cavity mold 22 for the resin molded product in FIG. 2A. As shown in FIG. 1, the coated resin molded product (in-mold coated molded product) 20 according to embodiment 1 includes the resin molded product 10 and a coating film 14 formed on the surface of the resin molded product 10. As shown in FIG. 2B, the resin molded product 10 has a plurality of grains 12 on its surface. The surface of the resin molded product 10 has an average length RSm of 300 μm or less according to JIS B0601 (ISO 4287). The coating film 14 has a film thickness of 0.01 mm or more and 1 mm or less. This resin molded product 20 with a paint film has multiple grains 12 on the surface of the resin molded product 10, and since the average length RSm of the surface is within the above range, an anchor effect is obtained for the paint film 14, making it difficult for the paint film 14 to detach from the surface.

[0026] The painted resin molded product 20 will be described in detail below.

[0027] While any resin suitable for injection molding can be used as the resin constituting the resin molded product 10, thermoplastic resins are particularly preferred. This is because thermosetting resins have a cross-linked structure, which stabilizes the molecular structure of the molded product surface and makes it difficult for in-mold paint to adhere. While any conventional paint used in in-mold painting can be used as the paint film 14, a thermosetting resin with a cross-linked structure is preferred. For example, two-component thermosetting urethane paint, one-component thermosetting acrylic paint, or ultraviolet-curable paint may be used. The paint may contain additives such as colorants, curing accelerators, and mold release agents. The surface of the resin molded product 10 has multiple grains 12. The grains may be, for example, multiple convex portions, multiple concave portions, linear portions, linear grooves, or any of these patterns. They may also be uneven patterns. The convex portions or concave portions may be, for example, cones, pyramids, cylinders, or truncated cones. The linear portions may be linear or curved. The surface of the resin molded article 10 may have a first ten-point mean roughness Rzjis of 0.5 μm or more and 50 μm or less, as measured in accordance with JIS B0601 (ISO 4287). The first ten-point mean roughness Rzjis may be 1 μm or more and 30 μm or less. Furthermore, the first ten-point mean roughness Rzjis may be 5 μm or more and 20 μm or less. The first ten-point mean roughness Rzjis is not limited to the above range, as long as it provides the effect of improving adhesion between the paint film and the resin molded article. The RSm and Rzjis can be measured, for example, by a measurement method in accordance with JIS B0633 (ISO 4288). The ranges of the RSm and Rzjis values ​​of the resin molded article 10 differ from those of a natural surface. Here, a natural surface is defined as, for example, a surface with small irregularities and a large pitch. Furthermore, the natural surface has an average length RSm of more than 300 μm according to JIS B0601 (ISO 4287). Therefore, the natural surface can be distinguished from the natural surface by the average length RSm. The thickness of the coating film 14 may be, for example, 0.05 mm or more and 0.5 mm or less. Furthermore, it may be 0.1 mm or more and 0.2 mm or less.

[0028] In this resin molded article 20 with a coating film, the thickness of the resin molded article 10 may, for example, have a lower limit of 1 mm or more, or 2 mm or more. The upper limit may be 5 mm or less, or even 4 mm or less. The lower limit of the thickness of the coating film 14 may, for example, be 0.01 mm or more, 0.05 mm or more, or 0.1 mm or more. The upper limit may be 1 mm or less, 0.5 mm or less, or 0.2 mm or less. Neither the thickness of the resin molded article 10 nor the thickness of the coating film 14 may be uniform. The thickness may, for example, be an average. There may be portions where the thickness exceeds the above range.

[0029] If the paint film is transparent, the grain of the resin molded product will be visible through the surface of the paint film, resulting in an appearance problem. To make the grain of the resin molded product less noticeable, it is necessary to control the reflective component at the interface between the paint film and the resin molded product. The resin molded product material is preferably a transparent resin with a transmittance of 80% or more per mm of thickness, or a resin containing at least one colorant composed of a pigment or dye. In particular, since the specular reflectance at the interface between the resin molded product and the paint film is high, it is preferable that the resin molded product does not contain metallic fillers with a size of 1 μm or more and a reflectance of 80% or more. The shape of the filler includes, for example, spherical, fibrous, and plate-like shapes. Furthermore, the paint film may contain at least one colorant containing a pigment or dye or the above-mentioned metallic filler. To achieve these effects, the refractive index difference between the resin molded product and the paint film may be 0.2 or less, preferably 0.05 or less.

[0030] <In-mold coating mold set> Fig. 6A is a schematic cross-sectional view showing the cross-sectional structure of a resin molding mold 26 consisting of a resin molded product cavity mold 22 and a core mold 24 when forming an out-mold type resin molded product. Fig. 6B is a schematic cross-sectional view showing the cross-sectional structure of a paint film mold 30 consisting of a paint film cavity mold 28 and an out-mold core mold 36 when forming an out-mold type paint film. Fig. 7A is a schematic cross-sectional view showing the cross-sectional structure of a resin molding mold 26a consisting of a resin molded product cavity mold 22 and a core mold 24 when forming a die-slide type resin molded product. Fig. 7B is a schematic cross-sectional view showing the cross-sectional structure of a paint film mold 30a consisting of a paint film cavity mold 28 and a core mold 24 when forming a die-slide type paint film. The in-mold coating mold set 40 according to embodiment 1 includes a resin molded product mold 26 and a paint film mold 30. As shown in FIGS. 6A and 6B , the in-mold coating mold set 40 may be a combination of an out-mold type resin molded product mold 26 and a paint film mold 30. The out-mold type refers to a mold in which the resin molded product mold 26 and the paint film mold 30 are provided separately. In this case, for example, after the resin molded product cavity mold 22 and the core mold 24 are opened, a separately provided paint film cavity mold 28 and an out-mold core mold 36 are combined to form the paint film mold 30. Alternatively, as shown in FIGS. 7A and 7B , the in-mold coating mold set 40a may be a die-slide type in-mold coating mold set in which the resin molded product cavity mold 22 and the paint film cavity mold 28 are slidably arranged relative to the core mold 24. In this case, after the resin molded product cavity mold 22 and the core mold 24 are opened, the paint film cavity mold 28 can be slid and clamped to the core mold 24 to form the paint film mold 30a. In the die-slide type in-mold coating mold set 40 a, the resin molding mold 26 and the coating film mold 30 can use a common core mold 24 .

[0031] <Mold for Resin Molded Product> As shown in FIG. 2A , the mold for resin molded product 26 according to the first embodiment includes a cavity mold for resin molded product 22 and a core mold 24. The surface of the cavity mold for resin molded product 22 is provided with a transfer texture 23 for transferring a texture 12 to the surface of the resin molded body 10. The cavity mold for resin molded product 22 and the core mold 24 are arranged to be movable relative to each other by a drive unit and an opening / closing unit (not shown). When the cavity mold for resin molded product 22 and the core mold 24 are clamped together, a cavity for resin molded product is defined therebetween. A resin molded product is formed by filling the cavity for resin molded product with resin. At this time, as shown in FIG. 2B , the resin molded product 10 is formed with texture 12 corresponding to the transfer texture 23 provided on the surface of the cavity mold for resin molded product 22. The transfer texture 23 may be, for example, a plurality of convex portions, a plurality of concave portions, linear portions, linear grooves, or any of these patterns. It may also be a concave-convex pattern. The convex or concave portions may be, for example, cones, pyramids, cylinders, or truncated cones. The linear portions may be linear or curved irregularities. Furthermore, the surface of the cavity mold 22 for a resin molded product has an average length RSm of 300 μm or less and a ten-point mean roughness Rzjis of 0.5 μm or more and 50 μm or less, as measured in accordance with JIS B0601 (ISO 4287). Furthermore, the ten-point mean roughness Rzjis may be, for example, 1 μm or more and 30 μm or less, as measured in accordance with JIS B0601 (ISO 4287). Furthermore, the ten-point mean roughness Rzjis may be 5 μm or more and 20 μm or less. The RSm and Rzjis can be measured, for example, by a measurement method as measured in accordance with JIS B0633 (ISO 4288).

[0032] The ranges of the surface roughness values ​​RSm and Rzjis of the cavity mold 22 for resin molded products are different from those of a natural surface. Here, a natural surface is defined as, for example, a surface with small irregularities and a large pitch. Furthermore, a natural surface has an average length RSm of more than 300 μm according to JIS B0601 (ISO 4287). Therefore, it can be distinguished from a natural surface by the size of the average length RSm.

[0033] <Mold for Coating Film> Fig. 3A is a schematic cross-sectional view showing the cross-sectional structures of a cavity mold for a coating film 28, a resin molded article 10, and a core mold 24 when a coating film is formed on the surface of the resin molded article 10 according to embodiment 1. Fig. 3B is an enlarged cross-sectional view showing the gap between the surface of the resin molded article 10 in Fig. 3A and the surface of the cavity mold for a coating film 28. Fig. 3C is an enlarged cross-sectional view showing the gap between the surface of the resin molded article 10 in Fig. 3A and the surface of a cavity mold for a coating film 28a according to Modification 1. As shown in Fig. 3A, the mold for a coating film 30 according to embodiment 1 includes a cavity mold for a coating film 28 and a core mold 24. The cavity mold for a coating film 28 and the core mold 24 are arranged so as to be movable relative to each other by a drive unit and an opening / closing unit (not shown). 3B, when the resin molded product 10 is placed on the core mold 24 and the paint film cavity mold 28 and the core mold 24 are clamped together, a paint film cavity, which is a gap, is defined between the paint film cavity mold 28 and the resin molded product 10. Paint is filled into this paint film cavity to form the paint film 14. This results in a resin molded product with a paint film (an in-mold coated molded product).

[0034] <Method for manufacturing a resin molded article with a coating film (in-mold coated molded article)> The resin molded article with a coating film according to embodiment 1 includes a resin molded article formation process (FIGS. 2A and 2B), a coating film mold clamping process (FIGS. 3A and 3B), a paint injection process (FIG. 4), a curing process (FIGS. 5A and 5B), and a coating film-coated resin molded article demolding process (not shown).

[0035] <Process for Forming Resin Molded Product> The resin molded product is formed using the resin molded product mold 26 of the in-mold coating mold set 40. Specifically, as shown in FIGS. 2A and 2B , the core mold 24 of the resin molded product mold 26 and the resin molded product cavity mold 22 are clamped together to define a resin molded product cavity corresponding to the resin molded product 10. Next, resin is introduced into the resin molded product cavity through the resin injection port 21. This forms the resin molded product 10. At this time, as shown in FIG. 2B , the resin molded product 10 is formed with a grain 12 corresponding to the transfer grain 23 provided on the surface of the resin molded product cavity mold 22. After the resin hardens, the core mold 24 and the resin molded product cavity mold 22 are opened to obtain the resin molded product 10.

[0036] <Mold clamping process of paint film mold> As shown in Figures 3A and 3B, when forming a paint film, a resin molded article 10 is placed on the core mold 24. An injector head 32 having a paint inlet 33 is attached to the paint film cavity mold 28, and the paint inlet 33 is positioned so as to be close to the paint gate portion 11. As shown in Figure 3B, when the core mold 24 and the paint film cavity mold 28 are clamped together, a paint film cavity 31 is defined between the resin molded article 10 and the paint film cavity mold 28.

[0037] <Paint Injection Process> Figure 4 is a schematic cross-sectional view showing how paint is injected into the gap between the paint film cavity mold 28 and the core mold 24 that constitute the paint film mold 30 when forming a paint film on the surface of the resin molded product 10 according to embodiment 1. As shown in Figure 4, paint 13 is introduced from an injector head 32 through a paint injection port 33 into the paint film cavity 31. The paint 13 fills the paint film cavity 31 to form a paint film.

[0038] <Curing Process> FIG. 5A is a schematic cross-sectional view showing the cross-sectional structures of the coating film cavity mold 28, the coating film 14, the resin molded product 10, and the core mold 24 when a coating film is formed on the surface of the resin molded product according to the first embodiment. FIG. 5B is an enlarged cross-sectional view showing the cross-sectional structures of the circled portion C of the coating film cavity mold 28, the coating film 14, and the resin molded product 10 in FIG. 5A . As shown in FIG. 5B , the coating material filled into the coating film cavity 31 is then cured. The curing method is not limited to the above-described method of curing by the passage of time; curing may also be performed by heating. Alternatively, curing may be performed by irradiating ultraviolet light or the like onto a portion of the mold made of a transparent material. The temperature of the molds 28 and 24 is preferably within a range that promotes curing of the coating material and increases the amount of shrinkage of the coating film 14, preventing visible irregularities on the surface of the coating film 14. For example, the temperature may be 60°C or higher and 130°C or lower. Alternatively, the temperature may be 80°C or higher and 110°C or lower.

[0039] <Mold release process for coated resin molded article> The coated cavity mold 28 and the core mold 24 are opened to remove the coated resin molded article 20. An ejector pin (not shown) may be provided inside the core mold 24 to push out the coated resin molded article 20 and release it from the core mold 24. Through the above steps, a coated resin molded article (in-mold coated molded article) 20 is obtained.

[0040] When releasing the resin molded article 20 with the coating film from the molds 24, 28, unless there is a certain or greater draft angle with respect to the vertical wall (vertical surface) of the resin molded article 10, the mold release resistance acts in the shear direction, and the effect of improving adhesion due to the grain cannot be expected. Therefore, as shown in Figure 5A, the draft angle θ of the surface of the coating film 14 with respect to the vertical wall (vertical surface) of the mold 28 is １ may be 1.5° or more, preferably 3° or more.

[0041] <Example> Flat plates with textures of different depths were prepared as resin molded articles 10, and in-mold coating was performed with a coating film 14 of 0.2 mm thickness. The surface area of ​​the resin molded articles 10 and the adhesion at the interface between the coating film 14 and the resin molded articles 10 were evaluated. As shown in Table 1 below, the flat resin molded articles 10 were textured to a depth of 1 μm to 20 μm. The surface area is shown as a value normalized with the case without texture being 1. The adhesion strength is also shown as a value normalized with the case without texture being 1.

[0042]

[0043] As shown in Table 1, it was confirmed that at a paint film thickness of 0.2 mm (200 μm), the deeper the grain, the better the adhesion. Both adhesion strength and surface area have a positive correlation with grain depth, but it was confirmed that adhesion strength increases more than the increase in surface area, especially when the depth exceeds 5 μm. This is thought to be due to the effect of simply increasing the adhesion area, as well as the effect of friction in the shear direction between the paint film and the resin molded product and the coating film shrinkage causing it to bite into the grain, further improving adhesion strength.

[0044] FIG. 8 is a partially enlarged cross-sectional view showing the cross-sectional structure of the surface of a resin molded product 20 with a paint film. Increasing the depth of the grain 12 of the resin molded product 10 increases adhesion strength, but the tradeoff is that deeper grain 12 reduces the surface flatness of the paint film 14, resulting in poor appearance. Table 2 below shows the results of examining the effect of grain 12 depth on appearance for paint film 14 thicknesses of 0.1 mm (100 μm) and 0.2 mm (200 μm). Evaluation was conducted on a five-point scale. This is thought to be due to the fact that, as shown in FIG. 8, if the grain 12 is too deep, the film thickness within the paint film 14 becomes non-uniform, resulting in significant differences in shrinkage of the paint film 14 within the surface, making the unevenness of the surface of the paint film 14 visible.

[0045]

[0046] (Embodiment 2) Figure 3C is an enlarged cross-sectional view showing the gap between the surface of the resin molded product 10 in Figure 3A and the surface of the cavity mold 28a for a paint film in an in-mold coating mold set according to embodiment 2. Figure 5C is an enlarged cross-sectional view showing the cross-sectional structures of the cavity mold 28a for a paint film, the paint film 14, and the resin molded product 10 in Figure 5A in an in-mold coating mold set according to embodiment 2. The resin molded product with a paint film according to embodiment 2 differs from the resin molded product with a paint film according to embodiment 1 in that, as shown in Figure 5C, multiple second embossments 16 are also provided on the surface of the paint film 14. The second embossments 16 may be, for example, multiple protrusions, multiple recesses, linear portions or linear grooves, or any of these patterns. They may also be an uneven pattern. The protrusions or recesses may be, for example, cones, pyramids, cylinders, or truncated cones. The linear portions may be linear or curved unevenness.

[0047] The surface of the coating film 14 has an average length RSm of 300 μm or less and a ten-point mean roughness Rzjis of 0.5 μm or more and 50 μm or less, as measured in accordance with JIS B0601 (ISO 4287). Furthermore, for example, the ten-point mean roughness Rzjis may be 1 μm or more and 30 μm or less, as measured in accordance with JIS B0601 (ISO 4287). Furthermore, the ten-point mean roughness Rzjis may be 5 μm or more and 20 μm or less. The RSm and Rzjis can be measured, for example, by a measurement method as measured in accordance with JIS B0633 (ISO 4288). The coating film has a thickness of 0.01 mm or more and 1 mm or less. By providing the second grain 16 on the surface of the coating film 14 and having the average length RSm and ten-point mean roughness Rzjis within the above ranges, the coating film becomes difficult to release from the coating film cavity mold and is prone to peeling. However, by providing the resin molded product with grain, the adhesion between the coating film and the resin molded product improves, and the coating film becomes easier to release from the coating film cavity mold when the coating film is formed.

[0048] The ranges of the surface roughness RSm and Rzjis of the coating film 14 are different from those of a natural surface. Here, a natural surface is defined as a surface with small irregularities and a large pitch. Furthermore, a natural surface has an average length RSm of more than 300 μm according to JIS B0601 (ISO 4287). Therefore, a coating film 14 can be distinguished from a natural surface by the magnitude of the average roughness RSm.

[0049] The in-mold coating mold set according to the second embodiment differs from the in-mold coating mold set according to the first embodiment in that a second transfer embossment 29 for transfer to the surface of the coating film is provided on the surface of the cavity mold 28a for the coating film. The second transfer embossment 29 may be, for example, a plurality of convex portions, a plurality of concave portions, a linear portion, a linear groove, or a pattern thereof. It may also be a concave-convex pattern. The convex portions or concave portions may be, for example, a cone, a pyramid, a cylinder, or a truncated cone. The linear portion may be a linear or curved concave-convex. The surface of the cavity mold 28a for the coating film has an average length RSm of 300 μm or less and a ten-point average roughness Rzjis of 0.5 μm or more and 50 μm or less, as measured in accordance with JIS B0601 (ISO 4287). Furthermore, for example, the ten-point average roughness Rzjis in accordance with JIS B0601 (ISO4287) may be 1 μm or more and 30 μm or less. Furthermore, the ten-point average roughness Rzjis may be 5 μm or more and 20 μm or less. The RSm and Rzjis can be measured, for example, by a measurement method in accordance with JIS B0633 (ISO4288).

[0050] The ranges of the surface roughness values ​​RSm and Rzjis of the cavity mold 28a for coating film differ from those of a natural surface. Here, a natural surface is defined as, for example, a surface with small irregularities and a large pitch. Furthermore, a natural surface has an average length RSm of more than 300 μm according to JIS B0601 (ISO 4287). Therefore, it can be distinguished from a natural surface by the average length RSm.

[0051] According to the resin molded article with a paint film according to the present disclosure, the resin molded article has a plurality of grains on the surface thereof, and the average surface length RSm of the grains is within the above range, thereby providing an anchoring effect for the paint film, making it difficult for the paint film to detach from the surface. Thus, the resin molded article is useful as an in-mold painted molded article.

[0052] REFERENCE SIGNS LIST 10 Resin molded product 11 Paint gate portion 12 Texture 13 Paint 14 Paint film 16 Second texture 20 Resin molded product with paint film (in-mold coated molded product) 21 Resin injection port 22 Cavity mold for resin molded product 23 Transfer texture 24 Core mold 26, 26a Mold for resin molded product 28, 28a Cavity mold for paint film 29 Second transfer texture 30, 30a Mold for paint film 31 Cavity for paint film 32 Injector head 33 Paint injection port 34 Mold base 36 Core mold for out-mold 40, 40a Mold set for in-mold coating

Claims

1. A resin molded product with a coating film, comprising a resin molded product and a coating film formed on the surface of the resin molded product, wherein the resin molded product has a plurality of grains on the surface, the surface has a first average length RSm of 300 μm or less in accordance with JIS B0601 (ISO4287), and the coating film has a thickness of 0.01 mm or more and 1 mm or less.

2. A resin molded product with a coating film according to claim 1, wherein the surface of the resin molded product has a first ten-point average roughness Rzjis in accordance with JIS B0601 (ISO4287) of 0.5 μm or more and 50 μm or less.

3. A resin molded product with a coating film according to claim 1, wherein the coating film has a plurality of grains on the surface, and the second average length RSm of the surface in accordance with JIS B0601 (ISO4287) is 300 μm or less.

4. A resin molded product with a coating film according to claim 3, wherein the surface of the coating film has a second ten-point average roughness Rzjis in accordance with JIS B0601 (ISO4287) of 0.5 μm or more and 50 μm or less.

5. A resin molded product with a paint film as described in claim 3, wherein the plurality of embossments on the surface of the paint film are provided in correspondence with the surfaces of the resin molded product on which the plurality of embossments are provided.

6. A mold for a resin molded product comprising a core mold for injection molding a resin molded product and a cavity mold for the resin molded product, wherein the cavity mold for the resin molded product has a plurality of transfer embossments on its surface to be transferred to the surface of the resin molded product, and the first average length RSm of the surface in accordance with JIS B0601 (ISO4287) is 300 μm or less.

7. A mold for forming a coating film, comprising a core mold for forming a coating film on the surface of a resin molded product and a cavity mold for forming a coating film, wherein the cavity mold for forming a coating film has a plurality of textures on its surface for transferring to the surface of the coating film, and the second average length RSm of the surface conforming to JIS B0601 (ISO4287) is 300 μm or less.

8. A mold set for in-mold coating, comprising: the mold for a resin molded product according to claim 6; and the mold for a coating film according to claim 7.

9. The mold set for in-mold coating according to claim 8, wherein the core mold for the mold for the resin molded product and the core mold for the mold for the coating film are a common core mold.

10. A mold set for in-mold coating as described in claim 8, wherein the multiple embossments on the surface of the cavity mold for the paint film of the mold for the paint film correspond to the multiple embossments on the surface of the cavity mold for the resin molded product of the mold for the resin molded product.

11. A mold set for in-mold coating as described in claim 8, wherein the cavity mold for the resin molded product of the mold for the resin molded product and the cavity mold for the paint film of the mold for the paint film are arranged so that their positions facing the core mold can be interchanged with each other.

Images