JP4438586B2 - In-mold painting method - Google Patents

Description

  The present invention relates to an in-mold coating molding method in which a coating film containing a glitter is formed on the surface of a substrate in a mold.

  In general, a resin molded product such as a wheel cap of a vehicle is manufactured by forming a base material and then forming a coating film on the surface of the base material. The coating film of such a resin molded product contains a fine flake-like glitter to give the appearance a metallic tone. However, if the orientation of the luminous body is disturbed when the coating film is formed, there is a problem that darkening due to irregular reflection of light occurs in the portion where the orientation is disturbed.

For this reason, a method of forming a coating film containing the luminous body on the surface of the base material while adjusting the orientation of the luminous body has been conventionally proposed. For example, in Patent Document 1, the luminous body is formed of a magnetic body, The paint is applied to the base material with a spray gun while adjusting the orientation of the luminous body by forming a magnetic field when forming the coating film outside the mold. Further, in Patent Document 2, the surface of the base material is applied while adjusting the orientation of the luminous body by adjusting the orientation of the luminous body by creating a steady flow of paint at the bent portion, which is a portion where the orientation of the luminous body is easily disturbed in the in-mold coating molding method. A film is formed.
JP-A-5-285448 Japanese Patent Laid-Open No. 2002-240091

  By the way, in Patent Document 1, since the paint dissolved in the solvent is applied to the base material taken out of the mold by the spray gun, it has to be repeatedly applied many times, and it takes time and has sufficient glitter. Could not be obtained. Furthermore, if there is a sink on the surface of the substrate, the paint is applied along the sink, so that the sink on the surface of the substrate will appear in the appearance of the product as it is, and this is a factor that deteriorates the design. It was. Further, in Patent Document 2, although the in-mold coating molding method is used, the mold for molding the base and the mold for forming the coating film are the same, and the mold is opened by a predetermined amount after the molding of the base. In order to inject the paint afterwards, a coating film cannot be formed on the surface of the base material parallel to the mold opening direction of the mold, resulting in a decrease in the degree of freedom in product design. was there.

  The present invention has been made paying attention to such problems existing in the prior art. Its purpose is in-mold coating molding that can improve the design of the product by adjusting the orientation of the glitter when forming the coating film, without reducing the degree of freedom in product design. It is to provide a method.

  In order to achieve the above object, the invention described in claim 1 is an in-mold coating molding method for forming a coating film on a surface of a substrate in a mold, and includes a first step of molding the substrate. And a second step of forming a coating film on the surface of the base material, wherein the first step is to fill the base material molding cavity formed by the fixed mold and the first moving mold with a synthetic resin. Forming the base material having the stepped portion, and the second step includes clamping the surface of the fixed mold and the second moving mold to form the surface of the base material and the second moving mold. Forming a coating film by forming a coating film by forming a coating film forming cavity between them, and filling the coating film forming cavity with a paint containing a luminous body, wherein the fixed mold and the second moving mold are At least one of the paint inlet for injecting the paint into the coating film forming cavity and the paint inlet A surplus paint container for accommodating the surplus paint that flows out of the coating film forming cavity when the paint is excessively injected, and the second moving mold includes the paint An insertion portion is disposed between the injection port and the surplus paint container, and is inserted into the step portion of the base material. In the second step, an excessive amount of the coating film forming cavity is provided. By injecting the paint, a steady flow of the paint toward the surplus paint containing portion through the insertion portion is formed, and the surplus paint is accommodated in the surplus paint containing portion. Then, the gist is to cure the paint.

  Therefore, since the mold for forming the base material is different from the mold for forming the coating film, even if the base material has a surface parallel to the mold opening direction, a coating film is formed on this surface. This reduces the degree of freedom in product design.

  In addition, the luminous body present in the coating film is regularly oriented along the flow of the coating material when the coating material is injected into the coating film forming cavity. At the time of forming the coating film, the flow of the paint divided into two by the insertion portion merges in the region closer to the surplus coating material housing than the insertion portion, and thus the orientation of the luminous body is particularly disturbed in the region. Although it is easy, even in this region, the luminous body is regularly oriented along the flow of the paint. For this reason, the reflected light of the light irradiated to the design surface of the product is regularly reflected by the luminous body regularly oriented along the surface of the coating film and proceeds in a certain direction, and the scattering is effectively suppressed. Is done. Accordingly, the design of the product exhibits the brightness almost uniformly over the entire surface, so that the design is enhanced. In particular, darkening (so-called meta unevenness) due to scattering of reflected light in the region is eliminated, and good glitter is ensured.

According to a second aspect of the present invention, in the in-mold coating molding method according to the first aspect, the surplus paint container is formed in a state where the fixed mold and the second movable mold are clamped. The gist is that the same number of insertion portions as the number of the insertion portions are arranged at positions facing the paint injection port with the insertion portion interposed therebetween .

In this way, when the coating film is formed, the flow of the paint divided into two by the insertion portion is merged in the region closer to the surplus paint containing portion than the insertion portion. Although the orientation of the luminous body tends to be disturbed, the luminous body can be regularly oriented along the flow of the paint, particularly in all of these regions.

  According to the present invention, an in-mold coating molding method capable of improving the design of a product by adjusting the orientation of a luminous body during the formation of a coating film without causing a decrease in the degree of freedom in product design. Can be provided.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is embodied in an in-mold coating method for a wheel cap of an automobile will be described with reference to FIGS.

  As shown in FIG. 1, a wheel cap 20 as an in-mold coated molded product (product) of this embodiment is attached so as to cover a wheel (not shown) of a tire 11 in an automobile 10.

  As shown in FIG. 2A, the wheel cap 20 has a disk shape. The wheel cap 20 has four opening portions 21 (through holes) as stepped portions, which are formed at equal angular intervals with respect to the center of the wheel cap 20. As shown in FIG. 2B, the wheel cap 20 includes a base material 22 made of a thermoplastic resin and a coating film 23 formed in a thin layer on the surface of the base material 22. Thus, the design surface of the wheel cap 20 is formed. In order to make the design surface of the wheel cap 20 metallic, the coating film 23 contains a large number of luminescent bodies 23a having a fine flake shape. Are regularly oriented.

Next, a method for manufacturing the wheel cap 20 will be described with reference to FIGS.
The wheel cap 20 is manufactured using the first mold 30 and the second mold 31.
As shown in FIG. 3, the 1st metal mold | die 30 is comprised from the fixed metal mold | die 32 and the 1st movement metal mold | die 33, and it clamps between both metal mold | die 32,33 by clamping up and down. A base material forming cavity 34 is formed. The first moving mold 33 is provided with a synthetic resin injection port 35 for injecting a thermoplastic resin as a material of the base material 22 into the central portion of the base material forming cavity 34. A convex portion 36 for forming the opening 21 in the base material 22 is formed on the cavity surface of the first moving mold 33.

  As shown in FIG. 5, the second mold 31 is configured by replacing the first moving mold 33 with a second moving mold 37, that is, the fixed mold 32 and the second moving mold 37. ing. The second mold 31 is a coating film forming cavity between the surface of the substrate 22 and the second movable mold 37 by clamping the fixed mold 32 and the second movable mold 37 in the vertical direction. 38 is formed. The second moving mold 37 is provided with a paint injection port 39 for injecting paint into the central part of the coating film forming cavity 38. On the cavity surface of the second moving mold 37, a convex portion 40 for forming the opening 21 in the coating film 23 is formed as an insertion portion.

  The fixed mold 32 has an excess paint container 41 for containing the excess paint that flows out from the coating film forming cavity 38 when the paint is excessively injected from the paint injection port 39. Is provided. The surplus paint container 41 is located outside the coating film forming cavity 38, and the surplus paint container 41 and the coating film forming cavity 38 communicate with each other. The surplus paint container 41 and the paint injection port 39 are disposed at positions facing each other with the convex part 40 in between with the second mold 31 being clamped. The same number (four) of the surplus paint accommodating portions 41 is provided corresponding to the number of the convex portions 40 (four in this embodiment). The four surplus paint containers 41 are arranged at equiangular intervals with respect to the paint inlet 39.

The process for manufacturing the wheel cap 20 includes a first process for forming the base material 22 using the first mold 30 and a second process for forming the coating film 23 on the surface of the base material 22. ing.
In the first step, as shown in FIG. 3, the base molding cavity 34 is formed by clamping the fixed mold 32 and the first movable mold 33. As shown in FIG. 4, the base material molding cavity 34 is filled with a molten thermoplastic resin injected from a synthetic resin injection port 35, cooled, and solidified by cooling to form a base material 22 having an opening 21. Is molded. At this time, the inner peripheral wall 21 a of the opening 21 of the base material 22 and the peripheral wall 22 a of the base material 22 are parallel to the mold opening direction of the first mold 30. Subsequently, the first moving mold 33 is moved upward to open the first mold 30, the first moving mold 33 is replaced with the second moving mold 37, and then the second step is performed.

  In the second step, as shown in FIG. 5, the fixed mold 32 and the second moving mold 37 are formed with the base material 22 molded in the first step placed on the fixed mold 32. Then, the coating film forming cavity 38 is formed between the surface of the substrate 22 and the second moving mold 37. At this time, the convex part 40 of the 2nd movement metal mold | die 37 is inserted in the opening part 21 formed in the base material 22 in the said 1st process. Subsequently, an excessive amount of thermosetting paint is injected into the central portion of the coating film forming cavity 38 from the coating material inlet 39 with respect to the volume of the coating film forming cavity 38. This paint contains a large number of the luminous bodies 23a in the form of fine flakes made of aluminum or the like.

  Then, as shown by arrows in FIG. 6, the coating material flows radially from the central portion of the coating film forming cavity 38 toward the outer edge portion and spreads over the entire coating film forming cavity 38. At this time, the luminous body 23a existing in the paint is regularly oriented along the flow of the paint. At this time, in the region closer to the surplus paint container 41 than the convex part 40, the flow of the paint divided into two by the convex part 40 merges, and the surplus paint is contained in the surplus paint container It flows into 41 and is accommodated. For this reason, a steady flow of the paint is formed in the coating film forming cavity 38 and passes around the convex portion 40 toward the surplus paint containing portion 41. Therefore, in the region on the surplus paint container 41 side of the convex part 40, the flow of the paint divided into two by the convex part 40 is merged, so that the orientation of the luminous body 23a is likely to be disturbed, Also in the region, the luminous body 23a is regularly oriented along the flow of the paint.

  Then, as shown in FIG. 7, after the coating film forming cavity 38 is filled with the coating material, the coating material 23 is formed on the surface of the substrate 22 by heating and curing the coating material. Thus, the wheel cap 20 is formed by performing the second step after performing the first step. After the wheel cap 20 is formed, the wheel cap 20 is removed from the second mold 31 by opening the second moving mold 37 upward.

According to the first embodiment described in detail above, the following effects are exhibited.
(1) Since the wheel cap 20 is different from the first mold 30 for forming the base material 22 and the second mold 31 for forming the coating film 23, the inside of the opening 21 (stepped portion) of the base material 22 is different. Even if the peripheral wall 21 a and the peripheral wall 22 a of the base material 22 are parallel to the mold opening direction of the first mold 30, the coating film 23 can be formed on these wall surfaces. For this reason, the fall of the freedom degree in designing the wheel cap 20 can be eliminated. In addition, since the first mold 30 for forming the base material 22 and the second mold 31 for forming the coating film 23 are different, the coating film can be uniformly formed on the surface of the base material 22.
(2) Since the first mold 30 for forming the base material 22 with a thermoplastic synthetic resin and the second mold 31 for forming the coating film 23 with a thermosetting paint are different, both the molds 30, 31 temperature management becomes easy.
(3) By forming the coating film 23 on the surface of the base material 22 in the mold, the surface of the coating film 23 is used as a design surface, so that the paint dissolved in the solvent is removed from the mold by a spray gun as in the past. Unlike the method of applying to the base material, even if there is a sink on the surface of the base 22, the sink can be hidden by the coating film 23, and high glitter can be obtained.
(4) When the coating material is poured into the coating film forming cavity 38, the flow of the coating material divided into two by the convex portion 40 is merged in the region of the surplus coating material accommodating portion 41 side with respect to the convex portion 40. Therefore, the orientation of the luminous body 23a is particularly disturbed in the region. However, even in the region, the presence of the surplus paint container 41 can form a steady flow of the paint, so that the luminous body 23a can be regularly oriented. For this reason, the reflected light of the light irradiated on the design surface of the wheel cap 20 is regularly reflected by the luminous body 23a regularly oriented along the surface of the coating film 23 and travels in a certain direction, and the scattered light is scattered. It can be effectively suppressed. Therefore, the design surface of the wheel cap 20 can exhibit glossiness almost uniformly over the entire surface, so that the design property can be enhanced. In particular, darkening (so-called meta unevenness) due to scattering of reflected light due to disorder of the alignment of the luminous body in the region can be eliminated, and good glitter can be ensured.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with a focus on differences from the first embodiment.

  As shown in FIG. 8, in the second embodiment, the fixed mold 32 is not provided with the surplus paint container 41. An electromagnet 50 extending along the parting line surface PL of the second mold 31 is embedded in the second moving mold 37. The electromagnet 50 is configured by winding the outer peripheral surface of a rod-shaped iron core 51 in a coil shape with a conductive wire 52 with insulation coating. The end of the conducting wire 52 is connected to a power source (not shown). When the conducting wire 52 is energized, magnetic lines 53 are generated in a direction along the parting line surface PL of the second mold 31, and a magnetic field is formed in the coating film forming cavity 38. In the second embodiment, the coating material for forming the coating film 23 contains a luminous body 23a made of a magnetic material such as iron, cobalt, or nickel.

  Now, when manufacturing the wheel cap 20, the base material 22 is first shape | molded by the method similar to the said 1st Embodiment. Next, as shown in FIG. 8, the second mold 31 is clamped to form the coating film forming cavity 38. Then, the conducting wire 52 is energized to generate a magnetic force line 53 in a direction along the parting line surface PL of the second mold 31 so that a magnetic field is formed in the coating film forming cavity 38. In this state, the paint is injected from the paint injection port 39.

  Then, the coating material flows radially from the central portion of the coating film forming cavity 38 toward the outer edge portion and spreads over the entire coating film forming cavity 38. At this time, the luminous body 23 a existing in the paint is regularly oriented along the magnetic force lines 53. Further, at this time, in the region on the outer edge side of the coating film forming cavity 38 with respect to the convex portion 40 (on the downstream side of the paint with respect to the convex portion 40), the paint divided into two by the convex portion 40 is provided. Since the flow merges, the orientation of the luminous body 23 a is particularly disturbed, but the luminous body 23 a is also regularly oriented along the lines of magnetic force 53 in the region. Then, as shown in FIG. 9, after the coating film forming cavity 38 is filled with the coating material, the coating material 23 is formed on the surface of the substrate 22 by heating and curing the coating material.

According to the second embodiment described in detail above, the following effects are exhibited in addition to (1) to (3) of the first embodiment.
(5) Since the luminous body 23a contained in the coating material has magnetism, the luminous body 23a is generated in the coating film forming cavity 38 when the coating material is injected into the coating film forming cavity 38. It can be oriented regularly along the magnetic field lines 53. In this case, in the region on the outer edge side of the coating film forming cavity 38 with respect to the convex portion 40 (on the downstream side of the paint with respect to the convex portion 40), the flow of the paint divided into two by the convex portion 40 is. Because of the merge, the orientation of the luminous body 23a is particularly disturbed in the region. However, even in the region, the luminous body 23a can be regularly oriented along the magnetic force lines 53 generated in the coating film forming cavity 38.

(Example of change)
In addition, the said embodiment can also be changed and actualized as follows.
-In 1st Embodiment, you may provide the surplus coating material accommodating part 41 over the perimeter of the outer side of the cavity 38 for coating-film formation.

In the second embodiment, the electromagnet 50 may be provided outside the second mold 31.
-In 2nd Embodiment, you may provide the surplus coating material accommodating part 41 in the fixed metal mold | die 32 similarly to 1st Embodiment.

-In 1st and 2nd embodiment, the level | step-difference part (opening part 21) is not restricted to four.
-In 1st and 2nd embodiment, a level | step difference part (opening part 21) may be a recessed part and a convex part instead of a through-hole.

  In the first and second embodiments, the inner peripheral wall 21a of the opening 21 (stepped portion) of the base material 22 and the peripheral wall 22a of the base material 22 are not necessarily parallel to the mold opening direction of the first mold 30. Good.

In the first and second embodiments, the coating mold 39 may be provided in the fixed mold 32.
In the first and second embodiments, the surplus paint container 41 may be provided in the second moving mold 37.

Further, the technical idea that can be grasped from each of the embodiments will be described below.
(1) The coating material injection port is disposed at the center of the coating film forming cavity, and the surplus coating material container is disposed outside the coating film forming cavity. The in-mold coating molding method according to 1.

In this way, regardless of the position of the insertion portion, it is possible to form a steady flow of the paint from the paint inlet to the surplus paint storage portion through the insertion portion.
(2) The in-mold coating molding method according to claim 1, wherein a plurality of the surplus paint containing portions are arranged at equiangular intervals around the paint injection port.

If it does in this way, the steady flow of the paint which goes to the surplus paint storage part through the circumference of the insertion part from the paint injection hole can be formed with good balance.
(3) The in-mold coating molding method according to claim 1, wherein the same number of surplus paint containing portions as the insertion portions are provided.

  In this way, when the coating film is formed, the flow of the paint divided into two by the insertion portion is merged in the region closer to the surplus paint containing portion than the insertion portion. Although the orientation of the luminous body tends to be disturbed, the luminous body can be regularly oriented along the flow of the paint, particularly in all of these regions.

The perspective view which shows the motor vehicle with which the wheel cap of 1st Embodiment was attached. (A) is a perspective view of the wheel cap of 1st Embodiment, (b) is the 2b-2b sectional view taken on the line of (a). Sectional drawing which shows the clamping state of the 1st metal mold | die in the 1st process of 1st Embodiment. Sectional drawing which shows the shaping | molding state of the base material in the 1st process of 1st Embodiment. Sectional drawing which shows the clamping state of the 2nd metal mold | die in the 2nd process of 1st Embodiment. The top view which shows the flow of the coating material in the 2nd process of 1st Embodiment. Sectional drawing which shows the formation state of the coating film in the 2nd process of 1st Embodiment. Sectional drawing which shows the clamping state of the 2nd metal mold | die in the 2nd process of 2nd Embodiment. Sectional drawing which shows the formation state of the coating film in the 2nd process of 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 20 ... Wheel cap as in-mold coating molded product (product), 21 ... Opening part as level | step-difference part, 22 ... Base material, 23 ... Coating film, 23a ... Bright object, 32 ... Fixed mold, 33 ... 1st movement Metal mold 34 .. Base material forming cavity 37. Second moving mold 38. Coating film forming cavity 39. Paint inlet 40. Convex part as insertion part 41. Excess paint container 53 ... lines of magnetic force, PL ... parting line surface of the second mold.

Claims (2)

An in-mold coating method for forming a coating film on the surface of a substrate in a mold,
A first step of forming the base material, and a second step of forming a coating film on the surface of the base material,
The first step is a step of forming a base material having a stepped portion by filling a synthetic resin into a base material forming cavity formed by a fixed mold and a first moving mold,
The second step forms a coating film forming cavity between the surface of the substrate and the second moving mold by clamping the fixed mold and the second moving mold, It is a step of filling a coating film forming cavity with a paint containing a luminous body to form a coating film,
In at least one of the fixed mold and the second movable mold, a paint injection port for injecting the paint into the coating film forming cavity, and when the paint is excessively injected from the paint injection port A surplus paint container for accommodating the surplus paint that flows out from the coating film forming cavity is disposed, and the second moving mold includes a paint inlet and the surplus paint container. An insertion part is provided that is positioned between the stepped part of the base material,
In the second step, by injecting an excessive amount of the paint into the coating film forming cavity, a steady flow of the paint passing through the insertion portion toward the surplus paint containing portion is formed. An in-mold coating molding method comprising: curing the paint after the surplus paint is contained in the surplus paint container. The surplus paint container is the same as the number of the insertion parts at a position facing the paint injection port and the insertion part in a state where the fixed mold and the second moving mold are clamped. The in-mold coating molding method according to claim 1, wherein only the inner coating is formed.

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