JP2019006068A - Molding die - Google Patents

Abstract

To provide a molding die having excellent rust resistance, which can improve designability of a molding.SOLUTION: A molding die 20 has a mold base material 21, a ground layer 45 which is a plating layer formed so as to coat a molding surface of the mold base material 21, and a fine uneven layer 30 which is put on the ground layer 45 and is a plating layer formed so as to have fine uneven patterns 31 with an average projection diameter of 0.1 μm-2.0 μm.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a mold.

  Conventionally, a molding die as in Patent Document 1 below is known. The molding die described in Patent Document 1 is described as having a molding surface on which fine crystal irregularities are formed by coarsening of plating crystal nuclei generated by plating treatment. In addition, it is described that the texture (matte feeling) of a resin molded product can be improved by molding the resin molded product using this mold.

JP-A-8-72065

  However, in the configuration disclosed in Patent Document 1, the degree of fineness of the fine unevenness is neither disclosed nor suggested, and it is unclear what kind of unevenness can improve the design of the molded product. is there.

  As a result of intensive studies, the inventors of the present application have newly found the properties of fine irregularities that can enhance the design of the molded product. On the other hand, the inventors of the present application have confirmed that such a mold has another problem that rust is likely to occur in the mold base material due to the fine irregularities.

  This invention is completed based on the above situations, Comprising: It aims at providing the shaping | molding die excellent in the rust prevention property which can improve the designability of a molded article.

  In order to solve the above problems, a molding die of the present invention includes a mold base material, a base layer that is a plating layer formed so as to cover a molding surface of the mold base material, and the base layer. And a fine concavo-convex layer which is a plating layer formed so as to have fine concavo-convex having an average protrusion diameter of 0.1 μm to 2.0 μm.

  According to the present invention, since the mold includes the fine concavo-convex layer, the design of the design surface of the molded product can be improved as compared with a molded product formed using a mold that does not include the fine concavo-convex layer. Furthermore, according to the present invention, since the molding surface of the mold base material is covered with the underlayer, even if a hole such as a pit or a pinhole is formed in the fine uneven layer, the molding surface The mold base material is not exposed, and it is possible to suppress the occurrence of a situation in which the mold base material is rusted in such a place.

  The said structure WHEREIN: The said base layer may consist of the same metal plating as the said fine uneven | corrugated layer. According to such a configuration, the step of forming the base layer and the step of forming the fine uneven layer can be performed using the same apparatus, which is preferable.

  The said structure WHEREIN: The said foundation | substrate layer may consist of plating selected from chromium plating, nickel plating, nickel-phosphorus plating, and nickel-tungsten plating. According to such a configuration, a highly corrosion-resistant film can be formed on the molding surface of the mold base material, which is preferable.

  In the above configuration, a plating layer formed so as to cover the surface having the fine unevenness, and a coating layer having a layer thickness smaller than the layer thickness of the fine unevenness layer and harder than the fine unevenness layer, You may have. According to such a configuration, the surface having the fine irregularities is covered with the coating layer having a layer thickness smaller than the layer thickness of the fine irregularities layer, and thus the surface having the fine irregularities following the fine irregularities of the fine irregularities layer. It can be. For this reason, compared with the molded product shape | molded with the shaping | molding die which does not have such fine uneven | corrugated shape, the design property of the design surface of a molded product can be improved. Furthermore, since the coating layer is harder than the fine concavo-convex layer, occurrence of a situation where the fine concavo-convex shape of the molding surface is damaged can be suppressed.

  In the above configuration, the mold base material has unevenness for forming a texture on the surface of the molded product, and the fine unevenness layer has the fine unevenness finer than the unevenness of the mold base material. May be. According to such a structure, the design surface of a molded product can be made into a complicated shape by the unevenness | corrugation of a wrinkle and fine unevenness | corrugation, and the brightness and glossiness value of a molded product can be made still more suitable.

  ADVANTAGE OF THE INVENTION According to this invention, the shaping | molding die excellent in the rust prevention property which can improve the designability of a molded article can be provided.

Sectional drawing which shows the shaping | molding apparatus which concerns on Embodiment 1 of this invention. Flow chart showing the manufacturing process of the mold Sectional view of the mold base material showing the irregularities formed in the wrinkle pattern forming process Cross-sectional view of a mold showing an underlayer and a fine relief layer FIG. 4 is an enlarged cross-sectional view of a mold showing the underlayer and the fine uneven layer of FIG. Sectional drawing which expands and shows the design surface of the interior material for vehicles Explanatory drawing showing the 2nd plating process A photograph showing the surface of a test piece that was tested in Condition 1 A photograph showing the surface of a test piece that was tested under Condition 2 A photograph showing the surface of the test piece of Example 1 The flowchart which shows the manufacturing process of the shaping | molding die concerning Embodiment 2 of this invention. Enlarged sectional view of the mold showing the underlayer, fine relief layer and coating layer

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS. In this embodiment, the shaping | molding apparatus 10 (refer FIG. 1) for manufacturing the vehicle interior material 50 (molded article) is illustrated. The vehicle interior material 50 is made of, for example, a synthetic resin (for example, a thermoplastic resin such as polypropylene) and exhibits a black color. As the vehicle interior material 50, for example, a trim board (such as an upper trim or a lower trim) constituting a vehicle door trim can be cited.

  As shown in FIG. 1, the molding apparatus 10 includes a pair of molding dies 11 and 20 provided so as to be openable and closable, and an injection apparatus 15. The molding die 11 has a molding surface 11A for molding the back surface of the vehicle interior material 50, and the molding die 20 is a molding surface for molding the design surface 51 (front surface) of the vehicle interior material 50. 20A. In a state in which the pair of molding dies 11 and 20 are closed, a molding space S1 that follows the shape of the vehicle interior material 50 is formed between the molding surface 20A and the molding surface 11A arranged to face the molding surface 20A. In addition, a runner 12 is provided inside the mold 11, and the molten resin injected from the injection device 15 is supplied to the molding space S <b> 1 via the runner 12.

  As shown in FIG. 4, the mold 20 includes a mold base material 21, a base layer 45 laminated on the mold base material 21, and a fine uneven layer 30 laminated on the base layer 45. . For example, the mold base material 21 has a shape in which the molding surface 21A follows the outer shape of the vehicle interior material 50 by cutting a steel material containing iron as a main component and containing carbon, silicon, manganese, phosphorus, sulfur, and the like. ing. The underlayer 45 and the fine uneven layer 30 are two plating layers laminated on the molding surface 21 </ b> A of the mold base material 21.

  As shown in FIG. 3, the mold base material 21 has irregularities 23 for forming a texture on the design surface 51 of the vehicle interior material 50. Specifically, as shown in FIG. 2, three types of irregularities 23, 24, and 25 having different formation methods are formed on the molding surface 21 </ b> A of the mold base material 21. The unevenness 23 is formed by chemical etching, for example (see FIG. 3). The unevenness 24 is, for example, finer than the unevenness 23 and is formed by sandblasting (see FIGS. 3 and 4). The unevenness 25 is, for example, finer than the unevenness 24 and is formed by electrolytic etching (see FIG. 4). As the irregularities 25, the diameter D1 of the concave portions can be set to 10 μm or more, for example. In addition, the fineness of the unevenness | corrugation 23,24,25 mentioned above is an example, and is not limited to this.

  The underlayer 45 is made of a plating selected from any one of chromium plating, nickel plating, nickel-phosphorus plating, and nickel-tungsten plating. In the present embodiment, the base layer 45 is made of chrome plating and exemplified by a first plating step described later. The underlayer 45 is made of the same metal plating as the fine uneven layer 30.

  As shown in FIG. 5, the base layer 45 is a plating layer formed so as to cover the molding surface 21 </ b> A of the mold base material 21. The underlayer 45 is a so-called gloss plating, which is a plating layer having a substantially constant layer thickness and excellent smoothness, and is laminated so as to follow the irregularities 23, 24, 25 of the mold base material 21.

  As shown in FIG. 5, the underlayer 45 has a layer thickness T1 of 5 μm or more and 20 μm or less. As a result of diligent research, the inventors of the present application have found that the surface of the mold base material 21 is not exposed from the underlayer 45, and the smoothness of the surface of the underlayer 45 can be secured according to such a layer thickness. I found out. Further, the layer thickness of the base layer 45 is preferably 8 μm or more in that the molding surface 21A of the mold base material 21 is not exposed, and 15 μm or less from the viewpoint of making the surface follow the unevenness 23 of the mold base material 21. In particular, about 12 μm is preferable.

  The fine concavo-convex layer 30 is made of chrome plating and is formed by a second plating step to be described later. In FIG. 4, the fine unevenness 31 is schematically drawn, but the fine unevenness 31 has a complicated uneven shape as seen in the surface photograph of FIG. 10.

  The fine uneven layer 30 is a plating layer formed so as to have fine uneven portions 31 having an average protrusion diameter of 0.1 μm to 2.0 μm. The “average protrusion diameter” is obtained by observing the surface of the plating layer with a laser microscope at 9000 times and calculating an average value of the diameters of about 100 protrusions. In FIG. 5, the diameter D2 of one protrusion of the fine unevenness 31 is schematically shown. As a result of intensive studies, the inventors of the present application have a correlation between the average protrusion diameter of the fine unevenness 31 and the design of the vehicle interior material 50, and a mold having the fine unevenness layer 30 having such fine unevenness 31 20, the knowledge that the effect of improving the design of the vehicle interior material 50 is obtained. The fine irregularities 31 are finer than the irregularities 23 for forming the texture of the mold base material 21. In the present embodiment, the fine irregularities 31 are further finer than the irregularities 24 and 25 of the mold base material 21.

  The fine concavo-convex layer 30 is formed so that the arithmetic mean roughness Ra of the surface having the fine concavo-convex 31 is in the range of 0.2 μm or more and 1.0 μm or less. In addition, in order to avoid the influence of the unevenness 23, 24, 25, the measurement of “arithmetic average roughness Ra of the surface having the fine unevenness 31” is based on JIS B 0601-1994 using a test piece as described later. And do it. An arithmetic average roughness Ra of 0.2 μm or more is preferable because, for example, the surface can be rougher than the underlayer 45 (so-called gloss plating). Further, if the arithmetic average roughness Ra is 1.0 μm or less, for example, it can have unevenness 23 that can be formed by chemical etching and unevenness that is finer than the unevenness 24 that can be formed by a sandblasting process, which is preferable. .

  As shown in FIG. 5, the fine uneven layer 30 has a layer thickness T2 of 5 μm or more and 20 μm or less. As a result of intensive studies, the inventors of the present application have found that according to such a layer thickness, the fine irregularities 31 can be suitably formed on the plating layer. Furthermore, the layer thickness of the fine concavo-convex layer 30 is preferably 10 μm or more and 20 μm or less, particularly preferably about 15 μm, in forming the fine concavo-convex 31.

  As shown in FIG. 6, the design surface 51 of the vehicle interior material 50 has an uneven shape to which the uneven shape of the molding surface 20 </ b> A is transferred. 6 is obtained by transferring the fine unevenness 31 on the surface of the fine unevenness layer 30, and the unevenness 53 rougher than the unevenness 52 is obtained by transferring the shape of the unevenness 25 of the molding surface 20A. . And these unevenness | corrugations 52 and 53 are formed in the convex part surface and concave part inner surface of the embossing to which the unevenness | corrugation 23 of the molding surface 20A of the design surface 51 was transferred.

  Next, a method for manufacturing the mold 20 will be described. As shown in FIG. 2, the manufacturing method of the mold 20 includes forming a texture pattern for forming the unevenness 23, a sand blasting process for forming the unevenness 24, an etching process for forming the unevenness 25, and the base layer 45. A first plating step and a second plating step for forming the fine uneven layer 30.

(Wrinkle pattern forming process)
In the embossed pattern forming step, the unevenness 23 is formed by an etching process. The etching process is performed using an acidic solution (for example, nitric acid or the like) that corrodes the metal constituting the mold base material 21 and an acid-resistant ink that blocks the solution. First, after the mold base material 21 is cleaned, the surface other than the molding surface is masked with a tape or the like. Subsequently, the embossed pattern is transferred to the molding surface 21 </ b> A of the mold base material 21 with acid-resistant ink. Thereafter, the molding surface 21A is corroded using an acidic solution. Then, the portion covered with the acid-resistant ink remains without being corroded, and the portion not covered is corroded to form a recess. As a result, irregularities 23 are formed on the molding surface 21A of the mold base material 21 (see FIG. 3).

(Sandblasting process)
In the sand blasting process performed after the texture pattern forming process, the unevenness 24 is formed by performing sand blasting on the molding surface 21A of the mold base material 21. Specifically, the abrasive is sprayed from the nozzle onto the molding surface 21A using compressed air generated by a compressor or the like. Accordingly, the unevenness 24 (see FIG. 3) is formed by cutting the molding surface 21A with the abrasive. Here, for example, an abrasive having a particle size of 80 to 150 is used. In this way, since the particle size of the abrasive is larger than when using a larger abrasive (for example, 150 to 250), the impact force on the molding surface 21A is increased, resulting in unevenness. 24 is easier to form.

(Etching process)
In the etching process performed after the sandblasting process, the mold base material 21 is immersed in a plating bath similar to the second plating process described later and connected to a power source. Then, the mold base material 21 is used as an anode, and the electrode disposed in the plating bath is used as a negative electrode, whereby the mold base material 21 is subjected to electrolytic etching. Thereby, the iron component contained in the shaping | molding die 20 fuse | melts, and the unevenness | corrugation 25 is formed in the molding surface of the metal mold | die base material 21 (refer FIG. 4). The electrolytic etching is preferably performed at a current density of 15 to 20 A / dm ² and a processing time of 1 to 20 minutes. Under such conditions, a concave portion having a certain size (for example, a hole diameter of 10 μm or more, D1 in FIG. 4) can be reliably formed.

(First plating process)
In the first plating step performed after the electrolytic etching step, electroplating is performed using the same apparatus as in the second plating step described later. In the first plating step, for example, the treatment is performed at a lower current density and a higher bath temperature than in the second plating step. As a result, chromium ions in the plating bath 61 are reduced and deposited on the molding surface of the mold base material 21 as a plating layer having different properties from the plating layer constituting the fine uneven layer 30. In addition, although a 1st plating process is not limited to this, performing the manufacturing method of the shaping | molding die 20 using the same apparatus as a 2nd plating process is preferable.

(Second plating process)
In the second plating step performed after the electrolytic etching step, as shown in FIG. 7, the mold base material 21 is immersed in a plating bath (chromium plating bath, sergeant bath) containing chromic acid and sulfuric acid as main components, and the power source 63 Connect to. Then, the mold base material 21 is electroplated by using the mold base material 21 as a negative electrode and the electrode 62 as a positive electrode. Thereby, the chromium ions in the plating bath 61 are reduced and deposited as a plating layer on the molding surface of the mold base material 21. Here, the plating process is performed under the condition that the fine unevenness 31 is formed and the thickness of the plating layer is the thickness of the fine unevenness layer 30 described above.

  Next, a method for manufacturing the vehicle interior material 50 using the molding apparatus 10 will be described. First, as shown in FIG. 1, the pair of molds 11 and 20 are closed. As a result, a molding space S1 that follows the shape of the vehicle interior material 50 is formed between the molding surface 20A and the molding surface 11A. Next, through the runner 12, black molten resin is injected from the injection device 15 into the molding space S1. Then, the vehicle interior material 50 is shape | molded by cooling the molten resin with which shaping | molding space S1 was filled (molding process). Thereafter, the pair of molds 11 and 20 are opened, and the vehicle interior material 50 is removed. Thereby, manufacture of the interior material 50 for vehicles is completed.

  Then, the effect of this embodiment is demonstrated. According to the present embodiment, since the mold 20 includes the fine uneven layer 30, the design surface 51 of the vehicle interior material 50 has a better design than a molded product formed using a mold that does not include the fine uneven layer. Can be increased. Specifically, the design surface 51 of the vehicle interior material 50 molded with the molding die 20 of the present embodiment scatters light compared to a molded product molded with a molding die that does not include the fine uneven layer 30. Easy surface. Thereby, the light reflectance of the design surface 51 of the vehicle interior material 50 is lowered, and the brightness and gloss value of the design surface 51 can be lowered. Therefore, it is possible to provide the vehicle interior material 50 having a stronger blackness (low gloss and jet black).

  Furthermore, according to the present embodiment, since the molding surface 21A of the mold base material 21 is covered with the base layer 45, a hole such as a pit or a pinhole is temporarily formed in the fine uneven layer 30. In addition, the mold base material 21 is not exposed on the molding surface 20A of the mold 20, and the occurrence of rusting on the mold base material 21 at such a location can be suppressed. In addition, the antirust effect of the foundation layer 45 will be considered in a demonstration experiment to be described later. If rust is generated in the mold, it is necessary to peel the plating layer from the mold and perform the plating process again, which causes a problem in the production of the interior material for the vehicle. Furthermore, as a rust preventive measure for the mold, it may be possible to apply a rust preventive agent to the molding surface of the mold, but such a measure removes the rust preventive agent before the start of production of vehicle interior materials. Or it is necessary to perform about 10 shots after the start of production, which causes an increase in tact time and waste of materials. On the other hand, in the present embodiment, it is possible to take a rust prevention measure for the mold 20 without increasing the tact time and wasting materials.

  That is, according to this embodiment, in the technique of providing fine irregularities on the mold and improving the design properties of the molded product, the problem of anticorrosive measures for the mold 20 that has occurred accompanying the two types of properties is solved. By providing different plating layers, it is possible to solve both of them simultaneously.

  Furthermore, in this embodiment, since the shaping | molding die 20 is provided with the foundation | substrate layer 45 and the fine uneven | corrugated layer 30, it can suppress that defects, such as white haze, arise in the vehicle interior material 50. FIG. The white haze is generated by resin shrinkage in the process of solidifying the molten resin in the injection mold. In the present embodiment, the unevenness 23 for forming the texture is formed by an etching process, and a portion having an under shape or a nearly vertical shape may occur in the details of the unevenness 23 during the corrosion process. When resin contraction occurs at such a site, a Kasil phenomenon occurs and the surface of the resin product may be damaged. Such a flaw can be visually recognized as white haze in the molded product. On the other hand, in this embodiment, it is possible to smooth an under shape or a nearly vertical shape in the details of the unevenness 23 with two plating layers, and without causing damage to the design surface 51 during resin shrinkage. The vehicle interior material 50 can be molded (in a sliding state).

  Furthermore, according to this embodiment, since the molding surface 21A of the mold base material 21 is covered with the base layer 45, the uniformity of the convex portions and concave portions constituting the fine irregularities 31 can be improved. The molding surface 21A of the mold base material 21 may have unevenness in the ease of plating due to the material of the steel material, cutting and surface processing (processing for forming the irregularities 23, 24, and 25). On the other hand, the foundation layer 45 is a plating layer having smoothness, and the plating is easier to apply than the molding surface 21A of the mold base material 21. For this reason, by forming the fine uneven layer 30 on the surface of the base layer 45, the fine unevenness 31 is configured as compared with the case where the fine uneven layer 30 is directly formed on the molding surface 21A of the mold base material 21. A convex part and a recessed part become uniform.

  In the present embodiment, the foundation layer 45 is made of the same metal plating as the fine uneven layer 30. For this reason, the process of forming the base layer 45 and the process of forming the fine uneven layer 30 can be performed using the same apparatus, which is preferable.

  In the present embodiment, the underlayer 45 is made of plating selected from any one of chromium plating, nickel plating, nickel-phosphorus plating, and nickel-tungsten plating. For this reason, a highly corrosion-resistant film can be formed on the molding surface 21A of the mold base material 21, which is preferable.

  Further, in the present embodiment, the mold base material 21 has the unevenness 23 for forming a texture on the surface of the vehicle interior material 50, and the fine unevenness layer 30 has the fine unevenness 31 of the mold base material 21. It is finer than the unevenness 23. For this reason, the design surface 51 of the vehicular interior material 50 can be made into a complicated shape by the embossed irregularities 23 and the fine irregularities 31, and the brightness and gloss value of the vehicular interior material 50 can be further reduced. be able to.

  In the present embodiment, the foundation layer 45 and the fine uneven layer 30 are made of chromium. Since chromium has a higher thermal conductivity than iron, it is possible to suppress a situation in which the molding surface 20A is locally cooled, and to reduce molding defects (such as weld or gloss unevenness) of the vehicle interior material 50. it can. Chromium is suitable as a plating layer to be formed on the molding surface 20A because it has higher hardness and excellent wear resistance than iron, which is the main component of the molding die 20.

<Example>
EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not restrict | limited to a following example, unless the summary is exceeded.

First, the test piece of Example 1 was prepared as follows. In the test piece of Example 1, a plating layer corresponding to the foundation layer 45 is formed on one surface of a flat plate having the same material as the mold base material 21 by the first plating process, and fine irregularities are formed by the second plating process. A plating layer corresponding to the layer 30 is formed. The flat plate used for the test piece was a flat one. The first plating step was performed under the conditions of a current density of 20 A / dm ² and a bath temperature of 50 ° C. The second plating step was performed under the conditions of a current density of 30 A / dm ² and a bath temperature of 30 ° C. In addition, the average protrusion diameter of the fine unevenness | corrugation of the plating layer corresponding to the fine uneven | corrugated layer 30 shown in Example 1 was 0.6 micrometer.

  In Comparative Example 1, a test piece was prepared in the same manner as in Example 1 except that the first plating step was not performed.

Next, for the test pieces of Example 1 and Comparative Example 1, a demonstration experiment regarding rust prevention was performed. The demonstration experiment was performed under the following conditions 1 and 2. The photograph of the test piece experimented on condition 1 is shown in FIG. 8, and the photograph of the test piece experimented on condition 2 is shown in FIG. 8A and 9B, (A) is a photograph of Example 1, and (B) is a photograph of Comparative Example 1. FIG.
Condition 1: A saline solution having a salt concentration (3.5%) similar to that of seawater was sprayed on the surface of the test piece. Immediately after spraying, it was dried with a dryer and cured for 5 days in a factory using a mold. The environment during curing was a maximum temperature of 33 ° C. and a maximum humidity of 93%.
Condition 2: Water used for cooling the mold (groundwater with pH 6.0) was sprayed on the surface of the test piece. Immediately after spraying, it was dried with a dryer and cured for 5 days in a factory using a mold. The environment during curing was a maximum temperature of 33 ° C. and a maximum humidity of 93%.

  As a result of the demonstration experiment, in Condition 1, in Comparative Example 1, as shown in FIG. 8B, large rust was generated so as to spread around the periphery, and many spot-like small rusts were generated. On the other hand, in Example 1, generation | occurrence | production of rust was not confirmed as FIG. 8 (A) shows. Even if the mold is used in a coastal factory, the mold remains only in contact with air containing salt, and it is difficult to assume a situation where the mold directly contacts seawater. That is, it can be said that Condition 1 is a severer condition than the actual use environment. Even under such conditions, it was confirmed that Example 1 did not cause rust.

  Moreover, in Condition 2, in Comparative Example 1, as shown in FIG. 9B, a lot of spot-like small rusts were generated. On the other hand, in Example 1, generation | occurrence | production of rust was not confirmed as FIG. 9 (A) shows. Condition 2 assumes that the water used for cooling the mold hangs down on the mold when the mold cooling pipe is attached and detached.

  Consider the results of the above demonstration experiment. Here, the photograph which image | photographed 9000 times using the laser microscope the surface of the test piece of Example 1 is shown in FIG. As shown in this photograph, it can be seen that the plating layer corresponding to the fine concavo-convex layer 30 has a large number of holes such as pits and pinholes, which are shown as dark portions in FIG. It is inferred that such holes communicate with the plating layer corresponding to the base layer 45 in Example 1 and the flat plate corresponding to the mold base material in Comparative Example 1.

  It is known that an oxide film layer having high corrosion resistance is formed on the surface of the chromium plating such as the underlayer 45. For this reason, in Example 1, it is considered that the occurrence of rust is suppressed by covering the surface of the flat plate corresponding to the mold base material 21 with the base layer 45 in both conditions 1 and 2. On the other hand, such an oxide film is not formed on a metal such as iron contained in the mold base material 21. For this reason, in Comparative Example 1, it is considered that the flat plate corresponding to the mold base material 21 was dissolved by the corrosive liquid entering from the holes of the fine uneven layer 30 and rust was generated. Further, in Comparative Example 1, the presence of iron or the like, which is a spotless base potential, in the chromium oxide film, which is a noble potential even when viewed electrochemically, makes the part a local battery and the test piece. It is thought that corrosion was promoted.

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described with reference to FIGS. 11 and 12. In the present embodiment, a mold 120 that is different from the first embodiment in that the coating layer 40 is provided is illustrated. In addition, the description which overlaps about the structure, an effect | action, and effect similar to above-described embodiment is abbreviate | omitted.

  As shown in FIG. 12, the mold 120 includes a mold base material 21, a base layer 45 laminated on the mold base material 21, a fine uneven layer 30 laminated on the base layer 45, and a fine uneven layer 30. And a coating layer 40 laminated to each other. The underlayer 45, the fine uneven layer 30, and the coating layer 40 are composed of three plating layers stacked on the molding surface 21 </ b> A of the mold base material 21.

  The covering layer 40 is made of chrome plating, and is formed by a third plating step described later. In addition, although the coating layer 40 is not limited to what consists of chromium plating, it is preferable when manufacturing the shaping | molding die 120 that it is set as the same metal plating as the fine uneven | corrugated layer 30. FIG.

  As shown in FIG. 12, the coating layer 40 is a plating layer formed so as to cover the surface having the fine irregularities 31 of the fine irregularities layer 30. The coating layer 40 is a plating layer having a substantially constant layer thickness and excellent smoothness, which is called so-called bright plating.

  As shown in FIG. 12, the covering layer 40 has a layer thickness smaller than the layer thickness of the fine uneven layer 30. Specifically, the coating layer 40 has a layer thickness of 0.1 μm or more and 10 μm or less. As a result of intensive studies by the inventors of the present application, according to such a layer thickness, an uneven shape that closely follows the fine unevenness 31 is suitably formed on the surface of the coating layer 40 (the surface opposite to the fine uneven layer 30). Found to get. Further, the layer thickness of the coating layer 40 is preferably 0.6 μm or more from the viewpoint of scratch resistance of the mold 120, and is preferably 5 μm or less from the viewpoint of making the surface follow the fine irregularities 31, particularly about 5 μm. preferable.

  The coating layer 40 is harder than the fine uneven layer 30. Specifically, the coating layer 40 has a Vickers hardness (Hv) greater than 300. In the present embodiment, the mold base material 21 has a hardness of Hv170, the fine uneven layer 30 has a hardness of Hv300, and the coating layer 40 has a hardness of Hv800. The hardness was measured in accordance with JIS Z 2244-2009. Moreover, in order to calculate the hardness of each layer of the fine uneven | corrugated layer 30 and the coating layer 40, the hardness of the plating layer corresponded to each layer formed in another test piece was measured, respectively.

  Next, a method for manufacturing the mold 120 will be described. As shown in FIG. 11, the manufacturing method of the forming mold 120 forms a texture pattern forming step for forming the unevenness 23, a sand blasting process for forming the unevenness 24, an etching step for forming the unevenness 25, and the base layer 45. A first plating step, a second plating step for forming the fine uneven layer 30, and a third plating step for forming the coating layer 40. Note that the texture pattern forming step, the sandblasting step, the etching step, the first plating step, and the second plating step are the same as those in the first embodiment, and the description thereof is omitted.

(Third plating process)
In the third plating step performed after the second plating step, electroplating is performed using the same apparatus as in the second plating step. In the third plating step, for example, the treatment is performed in a shorter time than the first plating step at the same current density and bath temperature as in the first plating step. As a result, chromium ions in the plating bath 61 are reduced, and deposited on the surface of the fine uneven layer 30 having the fine unevenness 31 as a plating layer having the same properties as the underlayer 45 and having a smaller layer thickness. To do. In addition, although a 3rd plating process is not limited to this, it is preferable when performing the manufacturing method of the shaping | molding die 120 efficiently using the same apparatus as a 2nd plating process.

  In the present embodiment, the surface having the fine irregularities 31 is covered with the coating layer 40 having a layer thickness smaller than the thickness of the fine irregularities layer 30, so that the molding surface 20 </ b> A of the mold 120 becomes the fine irregularities 31 of the fine irregularities layer 30. It can be set as the surface which has the fine uneven | corrugated shape to follow. For this reason, compared with the vehicle interior material shape | molded with the shaping | molding die which does not have such a fine uneven | corrugated shape, the design of the design surface 51 of the vehicle interior material 50 can be improved. Furthermore, since the coating layer 40 is harder than the fine uneven layer 30, it is possible to suppress the occurrence of a situation in which the fine uneven shape of the molding surface 20A of the mold 120 is damaged.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) In the above embodiment, the injection mold is exemplified as the mold, but the present invention is not limited to this. The molding die only needs to be used in a molding method in which the shape of the molding surface is transferred to the surface of the molded product, and examples thereof include a press molding die used for press molding and a vacuum molding die used for vacuum molding.
(2) In the above embodiment, the plating layer is chrome, but the present invention is not limited to this. For example, the plating layer may be made of a metal other than chromium (such as nickel or copper).
(3) In the said embodiment, although the vehicle interior material was illustrated as a molded article, a molded article is not restricted to this. Moreover, although the upper trim and the lower trim were illustrated as vehicle interior materials, it is not limited to this. The vehicle interior material only needs to be a member that is provided on the vehicle and has a design surface. Examples thereof include a skin material made of synthetic resin (for example, olefin-based thermoplastic elastomer), an instrument panel, an assist grip, and the like. be able to. Moreover, the vehicle interior material may be composed of a plurality of layers.
(4) In the said embodiment, although what exhibited black as a vehicle interior material was illustrated, the color of a vehicle interior material is not limited to black. Even when it is applied to a vehicle interior material that exhibits a color other than black, the brightness and glossiness thereof can be lowered.
(5) In the said embodiment, although the structure in which the unevenness | corrugation 23,24,25 was formed in 20A of shaping | molding surfaces was illustrated, it is not limited to this. For example, of the three types of unevenness 23, 24, 25, only the unevenness 23 may be formed, or the unevenness 23 and other unevenness may be formed. Moreover, the formation method of the unevenness | corrugation 23 can also be changed suitably.
(6) The configuration of the plating bath is not limited to that described above. For example, as a plating bath, a silicic acid bath mainly containing chromic acid, sulfuric acid, and silicic acid may be used.
(7) In the said embodiment, although the vehicle interior material was illustrated, it is not limited to vehicles. The present invention can be applied to interior materials mounted on vehicles other than vehicles.

  (8) In the etching process of the above-described embodiment, chemical etching may be performed instead of electrolytic etching. For example, in chemical etching, the iron component contained in the mold can be melted by using, for example, an alkaline solution (such as sodium hydroxide or sodium carbonate) as an etchant. Moreover, it is preferable to set the etching time at this time, for example in the range of 0.5 to 24 hours. Further, the etching solution is not limited to an alkaline solution, and an acidic solution (such as nitric acid) may be used.

  DESCRIPTION OF SYMBOLS 20,120 ... Mold, 21 ... Mold base material, 21A ... Molding surface (molding surface of mold base material), 23 ... Concavity and convexity, 30 ... Fine concavo-convex layer, 31 ... Fine concavo-convex layer, 40 ... Cover layer, 45 ... Underlayer, 50 ... Interior material for vehicle (molded product), 51 ... Design surface (surface of molded product)

Claims (5)

Mold base material,
An underlayer that is a plating layer formed so as to cover the molding surface of the mold base material;
A mold having a fine concavo-convex layer which is a plating layer which is laminated on the underlayer and has a fine concavo-convex shape having an average protrusion diameter of 0.1 μm to 2.0 μm.   The mold according to claim 1, wherein the base layer is made of the same metal plating as the fine uneven layer.   3. The mold according to claim 1, wherein the underlayer is made of a plating selected from any one of chromium plating, nickel plating, nickel-phosphorus plating, and nickel-tungsten plating.   The plating layer formed so as to cover the surface having the fine unevenness, further comprising a coating layer having a layer thickness smaller than the layer thickness of the fine unevenness layer and harder than the fine unevenness layer. The mold according to any one of claims 3 to 4. The mold base material has irregularities for forming a texture on the surface of the molded product,
The mold according to any one of claims 1 to 4, wherein the fine uneven layer has the fine unevenness finer than the unevenness of the mold base material.

Images