Method and apparatus for manufacturing molded products with in-mold coating.

Abstract

When coating the outer surface of a molded substrate with a liquid coating agent, even if the protrusions formed on the outer surface of the molded substrate have fine and complex shapes, they will be appropriately displayed in the appearance of the product. [Solution] A molding substrate 2, which has protrusions 5 formed on its outer surface in advance according to a desired pattern, is mounted in a first mold 1. The molding substrate 2 is then covered with a second mold 3 to form coating gaps C1 and C2 between the outer surface of the molding substrate 2 other than the protrusions 5 and the inner surface of the second mold 3, and a coating agent flow gap X1 is formed between the top surface of the protrusions 5 and the inner surface of the second mold 3. Liquid coating agent 4 is injected into the coating gaps C1 and C2, passed through the coating agent flow gap X1, and flows from one side of the protrusions 5 to the other. The second mold 3 and the first mold 1 are brought closer together to reduce the coating agent flow gap X1, and at least a portion of the liquid coating agent 4 present in the coating agent flow gap X1 is removed from the coating agent flow gap X1.

Description

Technical Field

[0002]

[0001] The present invention relates to a method and an apparatus for manufacturing an in-mold coated molded product, which forms a coating gap between the outer surface of a molded base material accommodated inside a mold and the inner surface of the mold, injects a liquid coating agent into the coating gap, and forms a coating layer on the outer surface of the molded base material. In particular, the present invention relates to a method and an apparatus for manufacturing an in-mold coated molded product, in which convex portions corresponding to a desired pattern are formed in advance on the outer surface of the molded base material, and a coating layer can be formed on the outer surface of the molded base material excluding the convex portions.

Background Art

[0004] As such two-color molding, the convex portions formed on the outer surface of the molded substrate are formed in an enclosed shape where the inner side is surrounded with respect to the flow of the resin flowing through the gap, and two cutouts communicating the inside and outside are formed in the convex portions of the enclosed shape. A method is known in which the resin supplied to the gap outside the convex portions of the enclosed shape is made to flow into the inside of the convex portions of the enclosed shape from one cutout and flow out from the other cutout (see Patent Document 1). According to this method, due to the two cutouts formed in the convex portions of the enclosed shape, the resin outside the convex portions is guided to the inside, so that a resin layer is also formed inside the convex portions of the enclosed shape. As a result, a resin layer is formed on the outer surface of the molded substrate excluding the top surface of the convex portion, and a design corresponding to the shape of the convex portion is displayed on the appearance of the molded product.

[0005] Another method of two-color molding is known in which a tunnel is formed inside a mold into which a molded substrate having the aforementioned enclosed-shaped protrusions on its outer surface is mounted, so as to connect the outer and inner sides of the enclosed-shaped protrusions, and the resin supplied to the outer side of the enclosed-shaped protrusions is guided to the inner side of the enclosed-shaped protrusions through the tunnel (see Patent Document 2). In this method as well, the resin on the outer side of the enclosed-shaped protrusions is guided inward by the tunnel formed in the mold, so a resin layer is also formed on the inner side of the enclosed-shaped protrusions. As a result, a resin layer is formed on the outer surface of the molded substrate except for the top surface of the protrusions, and a design corresponding to the shape of the protrusions is displayed on the appearance of the molded product.

[0006] However, in two-color molding, since the second molding substrate is often a thermoplastic resin, forming thin films, commonly referred to as coatings, is difficult due to their high viscosity. Specifically, when heated and melted resin (thermoplastic resin) is filled into the mold, a skin layer is formed on the surface due to cooling, making it difficult to form thin films of 0.5 mm (= 500 μm) or less. On the other hand, the in-mold coating method (IMC) is characterized by the use of low-viscosity thermosetting resins that can form thin films of 500 μm or less, which is a major difference from general two-color molding. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] EP-A1-001987939 [Patent Document 2] Japanese Patent Application Publication No. 6-226780 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, according to the former method (Patent Document 1), the resin on the outside of the convex part is guided inward by two notches formed in the convex part of the enclosed shape. As a result, the shape of the convex part is deviated from its original shape (desired pattern) by the two notches, reducing its value as a design. For example, if the convex part is O-shaped, it is necessary to form notches in two places on the circumferential direction of the O, which inevitably imposes design constraints.

[0009] Furthermore, according to the latter method (Patent Document 2), the resin on the outside of the enclosed protrusion is guided inward by a tunnel formed in the mold. Therefore, it is practically impossible when the molded substrate has multiple enclosed protrusions. For example, when the molded substrate is a computer key and multiple alphabet designs such as "Backspace" are formed as protrusions on its top surface, or when a complex Chinese character design is formed as a protrusion on the top surface of the molded substrate, multiple tunnels would have to be formed in the mold to connect the inside and outside of all the enclosed shapes constituting the protrusions, which is structurally impossible to achieve with a mold. For this reason, it is limited to simple characters.

[0010] The object of the present invention, conceived in consideration of the above circumstances, is to provide a method and apparatus for manufacturing molded products with in-mold coating that allows the protrusions to be displayed on the product's appearance without impairing their original design, since there is no need to form notches in the protrusions, and that allows the protrusions to be displayed appropriately on the product's appearance even if they have fine and complex shapes, since there is no need to form tunnels in the mold. [Means for solving the problem]

[0011] According to the first invention devised to achieve the above objective, a method for manufacturing a molded product with in-mold coating is provided, comprising: mounting a molding substrate in a first mold; covering the molding substrate with a second mold to form a coating gap between the inner surface of the second mold and the outer surface of the molding substrate; and injecting a liquid coating agent into the coating gap to adhere to the outer surface of the molding substrate. The method is characterized by: first forming protrusions on the outer surface of the molding substrate according to a desired pattern; mounting the molding substrate with the protrusions in the first mold; covering the molding substrate mounted in the first mold with a second mold to form a coating gap between the outer surface of the molding substrate other than the protrusions and the inner surface of the second mold; and forming a coating agent flow gap between the top surface of the protrusions and the inner surface of the second mold; in this state, injecting a liquid coating agent into the coating gap, allowing the liquid coating agent flowing through the coating gap to pass through the coating agent flow gap and flow from one side of the protrusions to the other; and then bringing the second mold and the first mold closer together to reduce the coating agent flow gap, thereby removing at least a portion of the liquid coating agent present in the coating agent flow gap from the coating agent flow gap.

[0012] Furthermore, according to a second invention devised to achieve the above objective, a method for manufacturing an in-mold coated molded product is provided, comprising: mounting a molding substrate in a first mold; covering the molding substrate with a second mold to form a coating gap between the inner surface of the second mold and the outer surface of the molding substrate; and injecting a liquid coating agent into the coating gap to adhere to the outer surface of the molding substrate. The method is characterized by: forming protrusions on the inner surface of the second mold in advance according to a desired pattern; mounting the molding substrate in the first mold; covering the molding substrate mounted in the first mold with the second mold to form a coating gap between the inner surface of the second mold other than the protrusions and the outer surface of the molding substrate; and forming a coating agent flow gap between the top surface of the protrusions and the outer surface of the molding substrate; in this state, injecting a liquid coating agent into the coating gap, allowing the liquid coating agent flowing through the coating gap to pass through the coating agent flow gap and flow from one side of the protrusions to the other; and then bringing the second mold and the first mold closer together to reduce the coating agent flow gap, thereby removing at least a portion of the liquid coating agent present in the coating agent flow gap from the coating agent flow gap.

[0013] In the method for manufacturing molded products with in-mold coating according to the first and second inventions described above (hereinafter also referred to as the present invention), a flange portion may be formed in advance on the molded substrate, and when the molded substrate with the flange portion is mounted on the first mold and a coating agent flow gap is formed, the second mold may be pressed against the flange to prevent the liquid coating agent flowing in the coating gap from leaking out from between the second mold and the molded substrate, and the coating agent flow gap may be made the first flow gap.

[0014] In the method for manufacturing a molded product with in-mold coating according to the present invention, when bringing the second mold and the first mold closer together to reduce the coating agent flow gap and removing at least a portion of the liquid coating agent present in the coating agent flow gap from the coating agent flow gap, the flange portion may be pressed and compressed by the second mold by bringing the second mold and the first mold together, so that the coating agent flow gap becomes a second flow gap that is narrower than the first flow gap or zero.

[0015] In the method for manufacturing a molded product with in-mold coating according to the present invention, when the second mold and the first mold are brought closer together to reduce the coating agent flow gap and at least a portion of the liquid coating agent present in the coating agent flow gap is removed from the coating agent flow gap, a portion of the liquid coating agent flowing in the coating gap may be discharged through an overflow passage formed in the second mold.

[0016] In the method for manufacturing a molded product with in-mold coating according to the present invention, the convex portion may have an enclosed shape in which the inside is surrounded with respect to the flow of the liquid coating agent.

[0017] In the method for manufacturing molded articles with in-mold coating according to the present invention, the liquid coating agent may be a thermosetting resin.

[0018] In the method for manufacturing a molded product with in-mold coating according to the present invention, the viscosity of the thermosetting resin may be 1 mPa·s or more and 50 Pa·s or less before it is injected into the coating gap.

[0019] Furthermore, the present invention provides a manufacturing apparatus for a mold-coated molded product used in any of the above-described methods for manufacturing a mold-coated molded product, characterized in that an actuator for clamping and opening a mold by bringing a first mold and a second mold closer together and further apart is equipped with a control unit for adjusting the clamping stroke.

[0020] Furthermore, according to the present invention, a manufacturing apparatus for a mold-coated molded product used in any of the above-described methods for manufacturing a mold-coated molded product is provided, characterized in that the actuator that moves a first mold and a second mold closer together and further apart to clamp and open the mold is equipped with a control unit for adjusting the clamping force. [Effects of the Invention]

[0021] According to the present invention, the following effects can be achieved.

[0022] (1) According to the first invention, a molded substrate having protrusions formed on its outer surface according to a desired pattern is mounted in a first mold, and the molded substrate is covered with a second mold. At this time, a coating gap is formed between the outer surface of the molded substrate other than the protrusions and the inner surface of the second mold, and a coating agent flow gap is formed between the top surface of the protrusions and the inner surface of the second mold. In this state, a liquid coating agent is injected into the coating gap, and the liquid coating agent flowing through the coating gap is passed through the coating agent flow gap and flows from one side of the protrusions to the other side. As a result, unlike in Patent Document 1, there is no need to form notches in the protrusions to allow the liquid coating agent to flow from one side of the protrusion to the other, and the protrusions corresponding to the desired pattern can be displayed on the product's appearance without impairing its original design. Furthermore, unlike in Patent Document 2, there is no need to form a tunnel in the mold connecting one side of the protrusion to the other in order to allow the liquid coating agent to flow from one side of the protrusion to the other, and the protrusions can be appropriately displayed on the product's appearance even if they have fine and complex shapes according to the desired pattern.

[0023] (2) Also, the mold closing of the first mold and the second mold is divided into two steps: a primary mold clamping step of forming a coating gap between the outer surface of the molding substrate other than the convex portion and the inner surface of the second mold and forming a coating agent flow gap between the top surface of the convex portion and the inner surface of the second mold, and a secondary mold clamping step of further approaching the first mold and the second mold from there to reduce the coating agent flow gap. In the primary mold clamping step, a liquid coating agent is injected into the coating gap, and then, in the secondary mold clamping, the first mold and the second mold are further approached to reduce the coating agent flow gap, and at least a part of the liquid coating agent present in the coating agent flow gap is excluded from the coating agent flow gap. Thereby, while ensuring fluidity by making the coating agent flow gap when flowing the liquid coating agent from one side to the other side of the convex portion a relatively large gap, the thickness of the coating film finally formed on the top surface of the convex portion by the liquid coating agent can be made a desired thickness including zero. Further, even if the height of the convex portion of the molding substrate varies to some extent due to the machining accuracy of the molding die for injection molding the molding substrate, the stability of the molding conditions, etc., by setting the coating agent flow gap at the time of primary mold clamping to be large in consideration of the variation in the height of the convex portion, the liquid coating agent can be appropriately flowed from one side to the opposite side of the convex portion, and the yield is improved.

[0024] (3) As described above, according to the present invention, since there is no need to form a notch in the convex portion, the convex portion can be displayed on the appearance of the product without impairing the original design of the convex portion. Since there is no need to form a tunnel in the mold, even if the convex portion has a fine and complex shape, it can be appropriately displayed on the appearance of the product. Since the mold closing of the first mold and the second mold is divided into two steps, while ensuring fluidity when flowing the liquid coating agent from one side to the other side of the convex portion, the thickness of the coating film finally formed on the top surface of the convex portion by the liquid coating agent can be made a desired thickness including zero. Further, even if there is some variation in the height of the convex portion of the molding substrate, the liquid coating agent can be appropriately flowed from one side to the opposite side of the convex portion, and the yield is improved.

[0025] (4) The effects (1) to (3) of the first invention described above can also be achieved in the second invention, in which the convex portion is provided on the inner surface of the second mold instead of the molding base material, and a coating agent flow gap is formed between the top surface of the convex portion and the outer surface of the molding base material. Technically, it can be regarded as equivalent to the first invention, and thus the same effects can be exhibited.

Brief Description of the Drawings

[0026] [Figure 1] It is an explanatory drawing of a method and an apparatus for manufacturing an in-mold coating molded product according to an embodiment of the present invention (the first invention). FIG. 1(a) is a side sectional view of the first mold, the second mold, and the molding base material, and FIG. 1(b) is a perspective view of the molding base material. [Figure 2] An explanatory drawing of the mold unit in the primary mold clamping process in which the molding base material shown in FIG. 1(b) is sandwiched between the first mold and the second mold shown in FIG. 1(a), coating gaps C1 and C2 are formed between the outer surface of the molding base material and the inner surface of the second mold, and a coating agent flow gap X1 is formed between the top surface of the convex portion provided in advance on the molding base material and the inner surface of the second mold. FIG. 2(a) is a plan view of the mold unit, FIG. 2(b) is a sectional view taken along line b-b of FIG. 2(a) (at the time of primary mold clamping), and FIG. 2(c) is a sectional view taken along line c-c of FIG. 2(a) (at the time of primary mold clamping). [Figure 3] An explanatory drawing of the injection process showing a state in which a liquid coating agent is injected into the coating gaps C1 and C2 in FIGS. 2(b) and 2(c), and the liquid coating agent flows from one side to the other side of the convex portion through the coating agent flow gap X1. FIG. 3(b1) is a sectional view of the injection process following FIG. 2(b), and FIG. 3(c1) is a sectional view of the injection process following FIG. 2(c). [Figure 4] An explanatory drawing in the secondary mold clamping process in which the first mold and the second mold are further approximated from the states in FIGS. 3(b1) and 3(c1) to reduce the coating agent flow gap X1 (to zero in this embodiment), and at least a part (all in this embodiment) of the liquid coating agent present in the coating agent flow gap X1 is excluded. FIG. 4(b2) is a sectional view at the time of secondary mold clamping following FIG. 3(b1), and FIG. 4(c2) is a sectional view at the time of secondary mold clamping following FIG. 3(c1). [Figure 5] Figures 1 to 5 illustrate the manufacturing method and apparatus for in-mold coated molded products according to this embodiment, with Figure 5(a) being a perspective view of the in-mold coated molded product and Figure 5(b) being a cross-sectional view taken along line bb in Figure 5(a). [Figure 6] Figure 6(a) is an explanatory diagram showing the main parts of a manufacturing method and manufacturing apparatus for a mold-coated molded product according to a modified embodiment (second invention) in which the protrusion is pre-provided on the inner surface of the second mold instead of the molding substrate. Figure 6(b) is a cross-sectional view of the main parts of the first mold, molding substrate, and second mold in the primary mold clamping step and subsequent injection step in which a coating agent flow gap is formed between the top surface of the protrusion on the inner surface of the second mold and the outer surface of the molding substrate. Figure 6(b) is a cross-sectional view of the main parts in the secondary mold clamping step in which the first mold and the second mold are brought even closer together to remove the liquid coating agent from the coating agent flow gap. [Modes for carrying out the invention]

[0027] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific numerical values ​​shown in these embodiments are merely illustrative to facilitate understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to the present invention are omitted from the illustrations.

[0028] (Overview of manufacturing method and manufacturing equipment for molded products with in-mold coating) A method for manufacturing a molded product with in-mold coating according to one embodiment of the present invention (first invention) is based on the following steps: as shown in Figures 1(a) and 1(b), a molded substrate 2 is mounted in a first mold 1; as shown in Figures 2(a), 2(b), and 2(c), the molded substrate 2 is covered with a second mold 3 to form coating gaps C1 and C2 between the inner surface of the second mold 3 and the outer surface of the molded substrate 2; and as shown in Figures 3(b1) and 3(c1), a liquid coating agent 4 is injected into the coating gaps C1 and C2 to adhere to the outer surface of the molded substrate 2.

[0029] Based on the above method, in this embodiment, first, as shown in Figure 1(b), protrusions 5 corresponding to a desired pattern are formed on the outer surface of the molded substrate 2, and the molded substrate 2 with the protrusions 5 formed is mounted on the first mold 1 as shown in Figures 1(a) and 2(b) (mounting step).

[0030] Next, as shown in Figures 2(b) and 2(c), the molded substrate 2 mounted in the first mold 1 is covered with the second mold 3, forming coating gaps C1 and C2 between the outer surface of the molded substrate 2 (excluding the protrusion 5) and the inner surface of the second mold 3, and forming a coating agent flow gap X1 between the top surface of the protrusion 5 and the inner surface of the second mold 3 (first mold clamping step).

[0031] In that state, as shown in Figures 3(b1) and 3(c1), liquid coating agent 4 is injected into coating gaps C1 and C2, and the liquid coating agent 4 flowing through coating gaps C1 and C2 is passed through the coating agent flow gap X1 and flows from one side of the protrusion 5 to the other side (injection step).

[0032] Subsequently, as shown in Figures 4(b2) and 4(c2), the second mold 3 and the first mold 1 are brought closer together to reduce the coating agent flow gap X1 (to zero in this embodiment), and at least a portion (all in this embodiment) of the liquid coating agent 4 present in the coating agent flow gap X1 is removed from the coating agent flow gap X1 (secondary mold clamping step).

[0033] The following describes each component.

[0034] (Molding base material 2) As shown in Figures 1(a) and 1(b), in this embodiment, the molded base material 2 has a rectangular upper plate portion 2a, a protrusion 5 formed on the upper plate portion 2a, side plate portions 2b extending downward from each of the four sides of the upper plate portion 2a, and a flange portion 6 formed along the circumferential direction at the lower end of the side plate portion 2b, and is in the shape of a hollow rectangular parallelepiped with an open bottom. The shape of the molded base material 2 is not limited to a hollow rectangular parallelepiped with an open bottom, but can be any shape that can be mounted on the core 1a of the first mold 1, such as a hollow triangular prism shape, a hollow hemisphere shape, or a hollow star shape with an open bottom.

[0035] The molded substrate 2 shown in Figures 1(a) and 1(b) is injection molded by placing a molding cavity, which is recessed in a separate molding die (not shown) from the second mold 3 used for coating, over the core 1a of the first mold 1, and injecting a molding resin (thermoplastic resin or thermosetting resin) into the molding gap formed between the molding cavity and the core 1a. After that, the molding die (not shown) is detached from the first mold 1, and the molded substrate 2 is mounted over the core 1a of the first mold 1 (see Figures 2(b) and 2(c)).

[0036] (Convex part 5) As shown in Figures 1(a) and 1(b), a protrusion 5 corresponding to a desired pattern (design) is integrally molded on the outer surface of the upper plate portion 2a of the molded substrate 2 during injection molding of the molded substrate 2 as described above. In this embodiment, the protrusion 5 is a double square ring consisting of an outer square ring and an inner square ring, but it may also be a single square ring, a round ring, a triangular ring, etc. Furthermore, the protrusion 5 is not limited to a ring shape (enclosed shape), but may also be an open shape such as a "く" shape, multiple letters such as "Back space", or any character, figure, or pattern including kanji.

[0037] As shown in Figures 2(b) and 2(c), if H is the height of the protrusion 5 formed on the upper plate portion 2a of the molded substrate 2 (the distance from the outer surface of the upper plate portion 2a to the top surface of the protrusion 5), and X1 is the coating agent flow gap between the top surface of the protrusion 5 and the inner surface of the cavity 3a of the second mold 3, then in the primary mold clamping process, the coating gap C2 between the outer surface of the upper plate portion 2a of the molded substrate 2 and the inner surface of the cavity 3a of the second mold 3 is the height H of the protrusion 5 plus the coating agent flow gap X1 (C2 = H + X1). This relationship (C2 = H + X1) is maintained in the injection process shown in Figures 3(b1) and 3(c1). In this embodiment, the height H of the protrusion 5 is set to 5 to 80 μm, and the coating agent flow gap X1 is set to 5 to 50 μm, so the coating gap C2 in the primary mold clamping process is H + X1 = 10 to 130 μm. However, the numerical ranges mentioned above are examples only and are not the only applicable ranges.

[0038] In the secondary clamping process shown in Figures 4(b2) and 4(c2), the first mold 1 and the second mold 3 are brought closer together, reducing the coating agent flow gap X1 between the top surface of the protrusion 5 and the inner surface of the cavity 3a in the injection process shown in Figures 3(b1) and 3(c1) (to zero in this embodiment). As a result, at least a portion (all in this embodiment) of the liquid coating agent 4 present in the coating agent flow gap X1 in Figures 3(b1) and 3(c1) is removed from the coating agent flow gap X1. In this embodiment, since the coating agent flow gap X1 is zero, in the secondary clamping process, the coating gap C2 between the outer surface of the upper plate portion 2a of the molded substrate 2 and the inner surface of the cavity 3a of the second mold 3 becomes equal to the height H of the protrusion 5.

[0039] Here, if the height H of the protrusion 5 shown in Figures 4(b2) and 4(c2) is set to be the same dimension as the coating gap C1 between the outer surface of the side plate portion 2b of the molded substrate 2 and the inner surface of the cavity 3a of the second mold 3 (H=C1), then the coating gap C2 between the outer surface of the upper plate portion 2a of the molded substrate 2 and the inner surface of the cavity 3a of the second mold 3 becomes C2=H=C1. In other words, in the secondary mold clamping process, the coating gap C2 between the outer surface of the upper plate portion 2a of the molded substrate 2 and the inner surface of the cavity 3a of the second mold 3 becomes equal to the coating gap C1 between the outer surface of the side plate portion 2b of the molded substrate 2 and the inner surface of the cavity 3a of the second mold 3. As a result, the thickness of the coating film formed by the liquid coating agent 4 in each coating gap C1 and C2 becomes equal, and as shown in Figures 5(a) and 5(b), the thickness of the coating film 8a on the upper plate portion 2a and the thickness of the coating film 8b on the side plate portion 2b of the product manufactured by this embodiment (in-mold coated product 7) become equal.

[0040] However, by making the coating gap C1 between the outer surface of the side plate portion 2b of the molded substrate 2 and the inner surface of the cavity 3a of the second mold 3 different from the coating gap C2=H between the outer surface of the upper plate portion 2a of the molded substrate 2 and the inner surface of the cavity 3a of the second mold 3 in the second mold clamping process shown in Figures 4(b2) and 4(c2), the thickness of the coating film 8a on the upper plate portion 2a and the thickness of the coating film 8b on the side plate portion 2b of the product (in-mold coated molded product 7) shown in Figure 5 can be made to be actively different. In other words, the coating film 8a on the upper plate portion 2a and the coating film 8b on the side plate portion 2b of the product (in-mold coated molded product 7) can each be any thickness.

[0041] (First mold 1) As shown in Figure 1(a), the first mold 1 (lower mold) has a base plate 1b with abutment surface 1c (PL surface) formed on its upper surface, and a core 1a protruding from the upper surface of the base plate 1b. The core 1a is formed to match the inner surface of the molded substrate 2. The molded substrate 2 is placed over the core 1a through its lower opening 2c. As shown in Figures 2(b) and 2(c), the molded substrate 2 mounted on the core 1a has its flange portion 6 seated on the abutment surface 1c. As described above, the first mold 1 is a mold used when injection molding the molded substrate 2, and is also used when forming coating films 8a and 8b on the outer surface of the molded substrate 2 with a liquid coating agent 4, as shown in Figures 2 and later.

[0042] (Second mold 3) As shown in Figure 1(a), the second mold 3 (upper mold) has a base block 3b with abutment surface 3c (PL surface) formed on its lower surface, and a cavity 3a recessed in the lower surface of the base block 3b. As shown in Figures 2(b) and 2(c), the cavity 3a is formed to be larger than the outer surface of the molded substrate 2 by the amount of the coating gap C1 in the width direction and by the amount of the coating gap C2 in the depth direction. The molded substrate 2 is inserted into the cavity 3a while mounted on the core 1a of the first mold 1.

[0043] As shown in Figures 3(b1) and 3(c1), injection passages 9 are formed on the side of the base block 3b for injecting liquid coating agent 4 into coating gaps C1 and C2. A heater (not shown) made of an electrical resistance wire such as a nichrome wire is embedded near the cavity 3a inside the base block 3b to heat-cur the liquid coating agent 4 (thermosetting resin) injected into the coating gaps C1 and C2 from the injection passages 9.

[0044] As shown in Figure 1(a), a flange receiving recess 10 is formed on the lower surface of the base block 3b along the edge of the cavity 3a. The flange portion 6 of the molded substrate 2 is accommodated in the flange receiving recess 10 during the primary mold clamping process shown in Figures 2(b) and 2(c).

[0045] (Flange section 6) As shown in Figure 1(b), the flange portion 6 of the molded substrate 2 is housed in the flange housing recess 10 of the second mold 3 during the primary mold clamping process, and pressed against the upper surface of the flange housing recess 10, as shown in Figures 2(b) and 2(c). That is, during the primary mold clamping process, the first mold 1 with the molded substrate 2 mounted is brought close to the second mold 3, and a predetermined coating agent flow gap X1 is formed between the top surface of the convex portion 5 of the molded substrate 2 and the inner surface of the cavity 3a of the second mold 3. At this time, the flange portion 6 of the molded substrate 2 is pressed against the flange housing recess 10 (edge ​​of the cavity 3a) of the second mold 3.

[0046] As a result, the flange portion 6 functions as a sealing material, preventing the liquid coating agent 4 flowing through the coating gaps C1 and C2 from leaking out between the flange portion 6 of the molded substrate 2 and the flange housing recess 10 of the second mold 3 during the injection process shown in Figures 3(b1) and 3(c1). At the same time, the flange portion 6 functions as a stopper that restricts the downward movement of the second mold 3, and the coating agent flow gap X1 between the top surface of the convex portion 5 of the molded substrate 2 and the inner surface of the cavity 3a of the second mold 3 is set to a predetermined gap (first flow gap X1).

[0047] In the primary clamping process shown in Figures 2(b) and 2(c), the clamping force used to bring the first mold 1 closer to the second mold 3 should be such that the flange portion 6 of the molded substrate 2, pressed against the flange receiving recess 10 of the second mold 3, functions as a sealing material. In most cases, leakage will not occur if the deflection amount X3 of the flange portion 6 is between zero and 10 μm. Therefore, it is desirable to set the clamping force in the primary clamping process to a force such that the deflection amount X3 of the flange portion 6 is between zero and 10 μm. However, if the injection pressure of the liquid coating agent 4 injected from the injection passage 9 into the coating gaps C1 and C2 shown in Figure 3(b1) is above a certain level, the clamping force in the primary clamping process may be increased so that the deflection amount X3 of the flange portion 6 during the primary clamping process is 20 μm or more, in order to reliably avoid leakage.

[0048] (Gap between abutment surfaces 1c and 3c) As shown in Figures 2(b), 2(c), 3(b1), and 3(c1), the depth of the flange housing recess 10 (the distance between the upper surface of the flange housing recess 10 and the abutment surface 3c of the second mold 3) is slightly smaller (for example, 5 to 50 μm) than the thickness of the flange portion 6 of the molded substrate 2. Therefore, when the flange portion 6 is pressed against the flange housing recess 10 during the primary mold clamping process shown in Figures 2(b) and 2(c), and during the injection process shown in Figures 3(b1) and 3(c1), a predetermined abutment gap X2 is formed between the abutment surface 1c of the first mold 1 and the abutment surface 3c of the second mold 3. This abutment gap X2 ensures a mold clamping stroke S1 that brings the first mold 1 and the second mold 3 closer together during the secondary mold clamping process shown in Figures 4(b2) and 4(c2), thereby reducing the coating agent flow gap X1 (first flow gap X1) between the top surface of the convex portion 5 and the inner surface of the cavity 3a.

[0049] In this embodiment, in the primary mold clamping process shown in Figures 3(b1) and 3(c1), the abutment gap X2 between the abutment surface 1c of the first mold 1 and the abutment surface 3c of the second mold 3 is set to be equal to the coating agent flow gap X1 (first flow gap X1) between the top surface of the protrusion 5 and the inner surface of the cavity 3a. As a result, in the secondary mold clamping process shown in Figures 4(b2) and 4(c2), when the abutment surface 1c of the first mold 1 is brought into contact with the abutment surface 3c of the second mold 3 to make the abutment gap X2 zero, the top surface of the protrusion 5 abuts against the inner surface of the cavity 3a, making the coating agent flow gap X1 zero, and the liquid coating agent 4 present in the coating agent flow gap X1 is completely removed.

[0050] In addition, in the injection process shown in Figures 3(b1) and 3(c1), the abutment gap X2 between the abutment surface 1c of the first mold 1 and the abutment surface 3c of the second mold 3 may be set smaller than the coating agent flow gap X1 between the top surface of the protrusion 5 and the inner surface of the cavity 3a. In this case, in the secondary mold clamping process shown in Figures 4(b2) and 4(c2), when the abutment surface 1c of the first mold 1 is brought into contact with the abutment surface 3c of the second mold 3 to set the abutment gap X2 to zero, a gap (second flow gap) is formed between the top surface of the protrusion 5 and the inner surface of the cavity 3a. Therefore, the liquid coating agent 4 present in the coating agent flow gap X1 is not completely removed, and a portion remains, forming a coating film with a thickness corresponding to the second flow gap on the top surface of the protrusion 5. The thickness of the coating on the top surface of the thus formed protrusion 5 is thinner by the height H of the protrusion 5 than the thickness of the coatings 8a and 8b (see Figures 5(a) and 5(b)) formed on the outer surface of the molded substrate 2 other than the protrusion 5 by the liquid coating agent 4. Therefore, the protrusion 5 can be distinguished from the other parts from the appearance of the finished product (in-mold coated molded product 7).

[0051] Furthermore, from the injection process in Figures 3(b1) and 3(c1) to the second mold clamping process in Figures 4(b2) and 4(c2), the mold clamping execution stroke S1 that brings the first mold 1 closer to the second mold 3 may be set to a stroke smaller than the coating agent flow gap X1 between the top surface of the protrusion 5 and the inner surface of the cavity 3a, using a position-controllable actuator which will be explained later. In this case as well, although the coating agent flow gap X1 between the top surface of the protrusion 5 and the inner surface of the cavity 3a shrinks by the amount of the mold clamping execution stroke S1, it does not become zero, so the liquid coating agent 4 present there is not completely removed, and some remains, forming a coating film on the top surface of the protrusion 5. The thickness of the coating on the top surface of the thus formed protrusion 5 is thinner by the height H of the protrusion 5 than the thickness of the coatings 8a and 8b (see Figures 5(a) and 5(b)) formed on the outer surface of the molded substrate 2 other than the protrusion 5 by the liquid coating agent 4. Therefore, the protrusion 5 can be distinguished from the other parts from the appearance of the finished product (in-mold coated molded product 7).

[0052] (Overflow path) By the way, when the injection process shown in Figures 3(b1) and 3(c1) is moved further closer to the first mold 1 and the second mold 3, and the process moves to the secondary mold clamping process shown in Figures 4(b2) and 4(c2), the volume of the coating gap C2 decreases according to the mold clamping stroke S1 (S1=X2 in this embodiment), so the internal pressure of the liquid coating agent 4 in the coating gaps C1 and C2 increases. As a result, the liquid coating agent 4 spreads properly to every corner of the coating gaps C1 and C2, preventing so-called short shots (poor filling). At this time, as shown in Figures 4(b2) and 4(c2), in accordance with the clamping stroke S1 between the first mold 1 and the second mold 3, the flange portion 6 of the molded substrate 2 is pressed against the flange receiving recess 10 of the second mold 3, the upper surface of the flange portion 6 is compressed and the corners of the flange receiving recess 10 bite into it, and the amount of deflection X3 of the flange portion 6 increases by the amount of the abutment gap X2 compared to Figures 3(b1) and 3(c1). Therefore, the sealing performance is improved and it is possible to prevent the liquid coating agent 4, whose internal pressure has increased in the coating gaps C1 and C2, from leaking from between the flange portion 6 of the molded substrate 2 and the flange receiving recess 10 of the second mold 3.

[0053] Furthermore, if the abutment gap X2 shown in Figures 3(b1) and 3(c1) is set relatively wide, and the mold clamping stroke S1 during secondary mold clamping is set relatively large, as shown in Figures 4(b2) and 4(c2), then during the secondary mold clamping process, the internal pressure of the liquid coating agent 4 in the coating gaps C1 and C2 may exceed the pressure required to properly distribute the liquid coating agent 4 to every corner of the coating gaps C1 and C2, potentially leading to leakage from between the flange portion 6 of the molded substrate 2 and the flange housing portion 10 of the second mold 3, or backflow from the injection passage 9. In this case, as shown in Figures 2(a) and 2(b), an overflow passage 11 can be formed in the second mold 3 on the opposite side of the injection passage 9, and during the secondary mold clamping process, the excess liquid coating agent 4 in the coating gaps C1 and C2 can be discharged through the overflow passage 11, thereby preventing the aforementioned leakage and backflow.

[0054] (Actuators for clamping and opening molds) In this embodiment, the actuator (not shown) that moves the first mold 1 and the second mold 3, shown in Figures 1 to 4, closer together and further apart to clamp and open the molds, is equipped with a control unit (not shown) for adjusting the clamping force. In such force control, a hydraulic cylinder is used for the actuator, and the control unit has the function of switching the clamping force from the hydraulic cylinder between a low-pressure clamping force and a high-pressure clamping force. The low-pressure clamping force is set such that, during the primary clamping process shown in Figures 2(b) and 2(c), and during the injection process shown in Figures 3(b1) and 3(c1), the flange portion 6 of the molded substrate 2 is pressed with an appropriate force against the flange housing recess 10 of the second mold 3, providing an appropriate sealing effect so that the liquid coating agent 4 in the coating gaps C1 and C2 does not leak from between the flange portion 6 of the molded substrate 2 and the flange housing recess 10 of the second mold 3, and an appropriate coating agent flow gap X1 is formed between the top surface of the convex portion 5 of the molded substrate 2 and the inner surface of the cavity 3a of the second mold. In this embodiment, the amount of deflection X3 of the flange portion 6 is 0 to 10 μm. The high-pressure clamping force is set to a force that further deflects the flange portion 6 during the secondary clamping process shown in Figures 4(b2) and 4(c2), causing the abutment surface 1c of the first mold 1 to abut against the abutment surface 3c of the second mold 3, and the abutment gap X2 to become zero. At this time, the amount of deflection X3 of the flange portion 6 is calculated by adding the deflection amount during the previous injection process (0 to 10 μm) to the dimension of the abutment gap X2 (X2 = X1 = 5 to 50 μm), resulting in a value of 5 to 60 μm.

[0055] Furthermore, the actuator that clamps and opens the first mold 1 and the second mold 3 may be equipped with a control unit for adjusting the clamping stroke. In such stroke control, a servo motor is used for the actuator, and the control unit has the function of switching the position of the servo motor between the first stroke and the second stroke. The first stroke is set to a stroke such that, during the primary clamping process shown in Figures 2(b) and 2(c), and during the injection process shown in Figures 3(b1) and 3(c1), the flange portion 6 of the molded substrate 2 appropriately contacts and presses against the flange housing recess 10 of the second mold 3, providing appropriate sealing performance so that the liquid coating agent 4 in the coating gaps C1 and C2 does not leak from between the flange portion 6 of the molded substrate 2 and the flange housing recess 10 of the second mold 3, and an appropriate coating agent flow gap X1 is formed between the top surface of the convex portion 5 of the molded substrate 2 and the inner surface of the cavity 3a of the second mold. At this time, the amount of deflection X3 of the flange portion 6 is 0 to 10 μm in this embodiment. The second stroke is set to be the stroke during the secondary mold clamping process shown in Figures 4(b2) and 4(c2) in which the flange portion 6 is further deflected so that the abutment surface 1c of the first mold 1 abuts against the abutment surface 3c of the second mold 3, and the abutment gap X2 becomes zero. At this time, the amount of deflection X3 of the flange portion 6 is the amount of deflection during the previous injection process (0 to 10 μm) plus the dimension of the abutment gap X2 (X2 = X1 = 5 to 50 μm), resulting in 5 to 60 μm. In practice, the position when the abutment surface 1c of the first mold 1 abuts against the abutment surface 3c of the second mold 3 is taken as the origin, and the stroke at a position separated from the origin by the coating agent flow gap X1 is defined as the first stroke during the primary mold clamping process, while the second stroke during the secondary mold clamping process is the stroke at which the abutment surface 1c of the first mold 1 abuts against the abutment surface 3c of the second mold 3, and the abutment gap X2 becomes zero.

[0056] (Material of molded base material 2) The molded substrate 2 shown in Figure 1(b) is formed by injection molding as described above. Either thermoplastic resin or thermosetting resin can be used as the material (molding resin) for the molded substrate 2.

[0057] For example, thermoplastic resins include polyolefin resins such as polyethylene, polypropylene, and ethylene-vinyl acetate polymer; crystalline general-purpose resins such as polyvinyl alcohol; crystalline engineering plastics such as polyamide, polyethylene terephthalate, and polyacetal; amorphous general-purpose resins such as polyvinyl chloride, polyvinylidene chloride, ABS resin, AES resin, ASA resin, and PMMA resin; amorphous engineering plastics such as polycarbonate, modified PPO, polyimide, polyarylate, and polyetherimide; and others such as polystyrene resin and thermoplastic elastomer. These can also be used in mixtures. Furthermore, it is possible to use materials that mix the above-mentioned thermoplastic resins with other components, such as thermosetting resins such as polyurethane resin, phenolic resin, melamine resin, and epoxy resin, while maintaining thermoplasticity. In addition, it is possible to use composite materials by adding various fibers such as carbon fibers and glass fibers to these various materials.

[0058] Examples of thermosetting resins include molding compounds called bulk molding compounds (BMC) and tough molding compounds (TMC), which use unsaturated polyester resins, phenolic resins, etc., as matrices.

[0059] (Material of liquid coating agent 4) As shown in Figure 3(b1), a thermosetting resin (e.g., thermosetting paint) is used as the liquid coating agent 4 injected from the injection passage 9 of the second mold 3 into the coating gaps C1 and C2. The thermosetting paint, as the liquid coating agent 4, is injected from the injection passage 9 of the second mold 3 into the coating gaps C1 and C2 between the inner surface of the cavity 3a and the outer surface of the molded substrate 2. It then receives heat from the second mold 3, which is heated by a heater (not shown), and hardens, adhering to the outer surface of the molded substrate 2 to form a coating film. As a heater, for example, an electrical resistance wire such as a nichrome wire can be placed near the cavity 3a of the second mold 3. Furthermore, temperature control is required for the heating method, and water temperature control is used when the set temperature is 120°C or less, and oil temperature control is used when it exceeds 120°C.

[0060] As for the material of the thermosetting resin (thermosetting paint) used in the liquid coating agent 4, in addition to thermosetting paints such as alkyd resin-based, epoxy resin-based, polyurethane-based, and vinyl resin-based paints, the following can be used: epoxy acrylate oligomers, urethane acrylate oligomers, polyester acrylate oligomers, radical polymerization type paints consisting of these various oligomers and ethylenically unsaturated monomers, oxidative polymerization type paints such as alkyd resin-based, epoxy resin ester-based, and fatty acid modified urethane resin-based paints, multi-component reactive type paints such as epoxy resin-based, polyurethane-based, and unsaturated polyester-based paints, or functional paints to which metal powders, pigments, ultraviolet absorbers, etc. have been added, fluororesin-based lacquers, silicone resin-based lacquers, silane-based hard coat agents, etc.

[0061] (Viscosity of liquid coating agent 4) One important condition for the liquid coating agent 4 used in this embodiment is viscosity. In this embodiment, the viscosity of the liquid coating agent 4 is 1 mPa·s to 50 Pa·s (preferably 2 Pa·s to 4 Pa·s) at room temperature (normal temperature) before it is injected into the coating gaps C1 and C2. If the viscosity of the liquid coating agent 4 exceeds 50 Pa·s, when the protrusions 5 on the top surface of the molded substrate 2 are made into a finely shaped design, for example, when the molded substrate 2 is a computer key and multiple alphabets such as "Backspace" are formed as protrusions 5 on its top surface, or when a complex Chinese character is formed as a protrusion 5 on the top surface of the molded substrate 2, it becomes difficult to fill the fine details of the protrusions 5 with the liquid coating agent 4, and in addition, it becomes difficult to remove excess liquid coating agent 4 from the fine details of the protrusions 5 during the secondary mold clamping process. Furthermore, a viscosity of 1 mPa·s is equivalent to that of water, and if the viscosity of the liquid coating agent 4 is less than 1 mPa·s, the fluidity will be too high, making it prone to leaking from between the flange portion 6 of the molded substrate 2 and the flange housing recess 10 of the second mold 3.

[0062] As shown in Figures 3(b1) and 3(c1), during the injection process, the liquid coating agent 4 (thermosetting paint) injected from the injection passage 9 into the coating gaps C1 and C2 has a relatively low viscosity of 1 mPa·s to 50 Pa·s (preferably 2 Pa·s to 4 Pa·s) at room temperature (room temperature), as described above. However, it receives heat from the second mold 3, which is heated by a heater (not shown), and the curing reaction begins, eventually hardening into a solid (coating film). Therefore, the mold closing operation in the next step, the secondary mold closing process, is preferably performed before the gel time (time when the curing reaction begins) of the liquid coating agent 4 (thermosetting paint), and must be performed at the latest by the cure time (time when curing is complete).

[0063] (Manufacturing process for molded product 7 with in-mold coating) Next, the manufacturing process of the molded product 7 with in-mold coating according to this embodiment will be described.

[0064] (Installation process) As shown in Figures 1(a) and 1(b), a molded base material 2 having a protrusion 5 at the top and a flange portion 6 at the bottom is mounted on the core 1a of the first mold 1. This molded base material 2 is injection molded by placing a molding cavity, which is recessed in a molding die (not shown) separate from the second mold 3 used for coating, over the core 1a of the first mold 1, and injecting a molding resin (the material of the molded base material 2 as described above: thermoplastic resin or thermosetting resin) into the molding gap formed between the molding cavity of the molding die and the core 1a of the first mold 1. After that, the molding die (not shown) is detached from the first mold 1, and the molded base material 2 is mounted over the core 1a of the first mold 1.

[0065] (Primary mold tightening process) Subsequently, as shown in Figure 1(a), a second mold 3 for coating is placed above the first mold 1, and the first mold 1 is raised and closed with a predetermined clamping force or predetermined clamping stroke. As a result, as shown in Figures 2(a), 2(b), and 2(c), the molded substrate 2 mounted on the core 1a of the first mold 1 is covered by the cavity 3a of the second mold 3, and coating gaps C1 and C2 are formed between the outer surface of the molded substrate 2 other than the protrusion 5 and the inner surface of the cavity 3a of the second mold 3, and a coating agent flow gap X1 is formed between the top surface of the protrusion 5 and the inner surface of the cavity 3a of the second mold 3. At this time, the flange portion 6 of the molded substrate 2 comes into contact with the flange housing recess 10 of the second mold 3 and flexes slightly (flexure amount X3 is zero to 10 μm), exhibiting the sealing function and stopper function described above.

[0066] A hydraulic cylinder or a servo motor is used as the actuator (not shown) for clamping and opening the first mold 1 and the second mold 3. When a hydraulic cylinder is used as the actuator, a control unit is provided to adjust the clamping force, and when a servo motor is used as the actuator, a control unit is provided to adjust the clamping stroke. During the primary clamping process, the clamping force or clamping stroke is appropriately adjusted by the control unit so that the flange portion 6 of the molded substrate 2 makes proper contact with the flange receiving recess 10 of the second mold 3, thereby achieving the sealing and stopping functions described above.

[0067] (Injection process) While maintaining the positional relationship between the first mold 1 and the second mold 3 in the primary mold clamping process, as shown in Figures 3(b1) and 3(c1), the liquid coating agent 4 (the thermosetting paint described above) is injected from the injection passage 9 of the second mold 3 into the coating gaps C1 and C2. The liquid coating agent 4 (thermosetting paint) flowing through the coating gaps C1 and C2 passes through the coating agent flow gap X1 and flows from one side of the protrusion 5 to the other. Therefore, as shown in Figure 1(b), even if the protrusion 5 is formed in an enclosed shape (square ring shape), the liquid coating agent 4 (thermosetting paint) can be guided into its interior.

[0068] The viscosity of the liquid coating agent 4 (thermosetting paint) is 1 mPa·s to 50 Pa·s (preferably 2 Pa·s to 4 Pa·s, 3 Pa·s in this embodiment) at room temperature before being injected into the coating gaps C1 and C2. By setting the viscosity of the liquid coating agent 4 (thermosetting paint) within this range, even if the protrusions 5 formed on the top surface of the molded substrate 2 have complex patterns (for example, designs such as multiple alphabets or Chinese characters), the liquid coating agent 4 (thermosetting paint) can be appropriately filled into the finely shaped parts of the protrusions 5, and excess liquid coating agent 4 (thermosetting paint) can be appropriately removed from the finely shaped parts of the protrusions 5 in the subsequent secondary mold clamping step.

[0069] (Secondary mold clamping process) The liquid coating agent 4 (thermosetting paint) introduced between the inner surface of cavity 3a and the outer surface of the molded substrate 2 receives heat from the second mold 3, which is heated by a built-in heater (not shown), and the curing reaction begins. Therefore, the secondary mold clamping process is preferably performed before the gel time when the curing reaction of the liquid coating agent 4 (thermosetting paint) begins, and must be performed at the latest by the cure time (curing completion time). In the secondary mold clamping process, as shown in Figures 4(b2) and 4(c2), the first mold 1 is brought closer to the second mold 3 to make the abutment gap X2 between the abutment surface 1c of the first mold 1 and the abutment surface 3c of the second mold 3 zero, and the coating agent flow gap X1 between the top surface of the convex portion 5 of the molded substrate 2 and the inner surface of cavity 3a of the second mold 3 zero. As a result, the top surface of the convex portion 5 comes into contact with the inner surface of cavity 3a, and all of the liquid coating agent 4 (thermosetting paint) present in the coating agent flow gap X1 is removed.

[0070] At this time, the volume of the coating gap C2 between the inner surface of the cavity 3a and the outer surface of the molded substrate 2 decreases, causing the internal pressure of the liquid coating agent 4 (thermosetting paint) in the coating gaps C1 and C2 to increase, allowing the liquid coating agent 4 (thermosetting paint) to reach every corner of the coating gaps C1 and C2, thus preventing so-called short shots. Also, as shown in Figures 4(b2) and 4(c2), during the secondary mold clamping process, the upper surface of the flange portion 6 of the molded substrate 2 is pressed against the flange housing recess 10 of the second mold 3 by the amount of the abutment gap X2 (X2=X1=5~50μm) shown in Figures 3(b1) and 3(c1). Therefore, the amount of deflection X3 of the flange portion 6 increases by the amount of the abutment gap X2 (5~50μm) compared to the amount of deflection during the primary mold clamping (0~10μm), becoming 5~60μm. As a result, the flange portion 6 of the molded substrate 2 is pressed so as to bite into the flange storage recess 10 of the second mold 3, preventing the liquid coating agent 4 (thermosetting paint), whose internal pressure has increased within the coating gaps C1 and C2, from leaking out from between the flange portion 6 of the molded substrate 2 and the flange storage recess 10 of the second mold 3.

[0071] If the clamping stroke S1 during the secondary clamping process is set to be larger than a certain extent, the internal pressure of the liquid coating agent (thermosetting paint) in the coating gaps C1 and C2 may become excessively high during the secondary clamping process, potentially causing the liquid coating agent 4 (thermosetting paint) to leak out from between the flange portion 6 of the molded substrate 2 and the flange housing recess 10 of the second mold 3, or to flow back into the injection passage 9. In this case, as shown in Figure 4(b2), a portion of the liquid coating agent 4 (thermosetting paint) with excessively high internal pressure in the coating gaps C1 and C2 is discharged from the overflow passage 11 formed in the second mold 3 on the opposite side of the injection passage 9. This prevents the aforementioned leakage and backflow.

[0072] (Ejection process) After the secondary mold clamping process shown in Figures 4(b2) and 4(c2), once the curing time for the liquid coating agent 4 (thermosetting paint) in the coating gaps C1 and C2 has elapsed, the first mold 1 is lowered, the mold is opened and released from the second mold 3, and the ejector pin (not shown) provided inside the core 1a is pushed out and abuts against the lower surface of the upper plate portion 2a of the molded substrate 2. As a result, the mold-coated molded product 7 (product) with coating films 8a and 8b formed on the molded substrate 2 by the liquid coating agent 4 (thermosetting paint) is ejected from the core 1a (see Figures 5(a) and 5(b)).

[0073] (In-mold coated molded product 7) Figures 5(a) and 5(b) show the molded product 7 with in-mold coating manufactured through the processes described above. On the outer surface of the molded substrate 2, coating films 8a and 8b of the liquid coating agent 4 (thermosetting paint) are formed, except for the top surface of the protrusions 5. In addition, an overflow portion 12 is formed at the joint between the side surface and the flange portion 6 of the molded product 7, where the liquid coating agent 4 (thermosetting paint) discharged from the overflow passage 11 shown in Figures 4(b2) and 2(a) has hardened. Since this overflow portion 12 rests on the upper surface of the flange portion 6, the problem of the liquid coating agent 4 (thermosetting paint) discharged from the overflow passage 11 shown in Figure 4(b2) dripping onto the abutment surface 1c of the first mold 1 (lower mold) can be avoided.

[0074] Furthermore, for example, if the molded substrate 2 shown in Figure 1(b) is molded with a colorless or colored transparent resin that is light-transmitting, and the liquid coating agent 4 injected into the coating gaps C1 and C2 from the injection passage 9 shown in Figure 3(b1) is a thermosetting paint that blocks light, then the upper surface of the in-mold coated molded product 7 shown in Figures 5(a) and 5(b) will have light transmission only at the protrusions 5, while the parts other than the protrusions 5 will be light-blocking. Here, the flange portion 6 is hidden by the other parts when the product (in-mold coated molded product 7) is assembled to other parts. Therefore, if lighting is placed on the back (inside) of the product (in-mold coated molded product 7) assembled to other parts, only the protrusions 5 will transmit light, and the design corresponding to the shape of the protrusions 5 will be visible from the outside.

[0075] (Effects / Actions) The manufacturing method and manufacturing apparatus for the mold-coated molded product 7 according to this embodiment can provide the following effects.

[0076] As shown in Figure 1(b), a molded substrate 2 with protrusions 5 formed on its outer surface according to a desired pattern is mounted on the core 1a of the first mold 1. As shown in Figures 2(b) and 2(c), the molded substrate 2 is covered with the cavity 3a of the second mold 3, thereby forming coating gaps C1 and C2 between the outer surface of the molded substrate 2 other than the protrusions 5 and the inner surface of the cavity 3a of the second mold 3, and forming a coating agent flow gap X1 between the top surface of the protrusions 5 and the inner surface of the cavity 3a of the second mold 3. In this state, as shown in Figures 3(b1) and 3(c1), liquid coating agent 4 (thermosetting paint) is injected into the coating gaps C1 and C2, and the liquid coating agent 4 flowing through the coating gaps C1 and C2 is passed through the coating agent flow gap X1 and flows from one side to the other of the protrusions 5.

[0077] As a result, according to the manufacturing method and apparatus for the in-mold coated molded product 7 of this embodiment, it is not necessary to form a notch in the protrusion 5 for flowing the liquid coating agent 4 from one side of the protrusion 5 to the other, as disclosed in Patent Document 1, and the protrusion 5 corresponding to the desired pattern can be displayed on the appearance of the product (in-mold coated molded product 7) without impairing its original design. Furthermore, as disclosed in Patent Document 2, it is not necessary to form a tunnel in the first mold 1 and the molding substrate 2 that connects one side of the protrusion 5 to the other in order to flow the liquid coating agent 4 from one side of the protrusion 5 to the other, and the protrusion 5 can be appropriately displayed on the appearance of the product even if it has a fine and complex shape according to the desired pattern.

[0078] Furthermore, according to the manufacturing method and apparatus for the mold-coated molded product 7 of this embodiment, the closing of the first mold 1 and the second mold 3 is divided into two stages: primary mold closing, which forms coating gaps C1 and C2 between the outer surface of the molded substrate 2 other than the protrusion 5 and the inner surface of the cavity 3a of the second mold 3, and forms a coating agent flow gap X1 between the top surface of the protrusion 5 and the inner surface of the cavity 3a of the second mold 3; and secondary mold closing, which further brings the first mold 1 and the second mold 3 closer together to reduce the coating agent flow gap X1. Liquid coating agent is injected into the coating gap during the primary mold closing stage, and then, during the second mold closing, the first mold 1 and the second mold 3 are brought further closer together to reduce the coating agent flow gap X1 (to zero in this embodiment), thereby removing at least a portion (all in this embodiment) of the liquid coating agent 4 present in the coating agent flow gap X1 from the coating agent flow gap X1.

[0079] In this way, the mold closing of the first mold 1 and the second mold 3 is divided into two stages, and in the first stage of mold closing, the liquid coating agent 4 is injected into the coating gaps C1 and C2, and the coating agent flow gap X1 is reduced by the second stage of mold closing (to zero in this embodiment), thereby removing at least a portion (all in this embodiment) of the liquid coating agent 4 from the coating agent flow gap X1. In the injection process shown in Figures 3(b1) and 3(c1), the coating agent flow gap X1 when the liquid coating agent 4 flows from one side of the protrusion 5 to the other side is made relatively large to ensure fluidity, and in the second stage of mold closing shown in Figures 4(b2) and 4(c2), the thickness of the coating film finally formed on the top surface of the protrusion 5 by the liquid coating agent 4 can be set to a desired thickness, including zero. The coating film formed on the top surface of the protrusion 5 by the liquid coating agent 4 is thinner than the coating film formed on the outer surface of the molded substrate 2 other than the protrusion 5 by the liquid coating agent 4. Therefore, even if the thickness is not zero, the design of the protrusion 5 according to the desired pattern can be visually distinguished from the parts other than the protrusion 5 from the appearance of the product (in-mold coated molded product 7).

[0080] Furthermore, the mold closing of the first mold 1 and the second mold 3 is divided into two stages. In the primary mold closing stage, liquid coating agent 4 is injected into the coating gaps C1 and C2. In the secondary mold closing stage, the coating agent flow gap X1 is reduced (to zero in this embodiment), and at least a portion (all in this embodiment) of the liquid coating agent 4 is removed from the coating agent flow gap X1. Therefore, even if the height H of the protrusions 5 of the molded substrate 2 varies to some extent due to the processing accuracy of the molding die (not shown) used to injection mold the molded substrate 2, the stability of the molding conditions, etc., by setting the coating agent flow gap X1 during primary mold closing, as shown in Figures 2(b) and 2(c), to be larger to account for the variation in the height H of the protrusions 5, the liquid coating agent 4 can be appropriately flowed from one side of the protrusions 5 to the other, thereby improving the yield.

[0081] As described above, according to the manufacturing method and apparatus for the mold-coated molded product 7 of this embodiment, there is no need to form a notch in the protrusion 5, so the protrusion 5 can be displayed on the appearance of the product (molded-coated molded product 7) without impairing the original design of the protrusion 5. Since there is no need to form a tunnel in the first mold 1 and the molding substrate 2, even if the protrusion 5 has a fine and complex shape, it can be appropriately displayed on the appearance of the product (molded-coated molded product 7). The fluidity of the liquid coating agent 4 when flowing the liquid coating agent 4 from one side of the protrusion 5 to the other side can be ensured, and the thickness of the coating film finally formed on the top surface of the protrusion 5 by the liquid coating agent 4 can be set to a desired thickness, including zero. Even if there is variation in the height H of the protrusion 5 of the molding substrate 2, the liquid coating agent 4 can be appropriately flowed from one side of the protrusion 5 to the opposite side, improving the yield.

[0082] (Modified embodiment: Second invention) In the above-described embodiment, as shown in Figure 1(b), a protrusion 5 corresponding to a desired pattern is provided in advance on the upper plate portion 2a of the molded substrate 2, and as shown in Figures 2(b) and 2(c), when the molded substrate 2 is covered with the cavity 3a of the second mold 3, a coating agent flow gap X1 is formed between the top surface of the protrusion 5 and the inner surface of the cavity 3a of the second mold 3. However, the upper plate portion 2a of the molded substrate 2 may be made flat without providing the protrusion 5, and instead, a protrusion 5 corresponding to a desired pattern is provided in advance on the inner surface of the cavity 3a of the second mold 3, and when the molded substrate 2 is covered with the cavity 3a, a coating agent flow gap X1 is formed between the top surface of the protrusion 5 and the outer surface of the upper plate portion 2a of the molded substrate 2. A brief explanation follows below.

[0083] In the modified embodiment, as in the previous embodiment, the premise is a method for manufacturing an in-mold coated molded product in which, as shown in Figure 1(a), a molded substrate 2 is mounted in the first mold 1, and as shown in Figures 2(b) and 2(c), the molded substrate 2 is covered with the second mold 3 to form coating gaps C1 and C2 between the inner surface of the second mold 3 and the outer surface of the molded substrate 2, and as shown in Figures 3(b1) and 3(c1), a liquid coating agent 4 is injected into the coating gaps C1 and C2 and adhered to the outer surface of the molded substrate 2.

[0084] The main parts of a modified embodiment based on this method are shown in Figures 6(a) and 6(b). In the modified embodiment, first, as shown in Figure 6(a), a protrusion 5x corresponding to the desired pattern is formed in advance on the inner surface of the cavity 3a of the second mold 3, and the molded base material 2 is mounted on the core 1a of the first mold 1. The upper surface of the upper plate portion 2a of the molded base material 2 is a flat surface (mounting process).

[0085] Next, as shown in Figure 6(a), the molded substrate 2 mounted in the first mold 1 is covered by the cavity 3a of the second mold 3, forming a coating gap C2 between the inner surface of the cavity 3a of the second mold 3 (excluding the protrusion 5x) and the outer surface of the molded substrate 2, and forming a coating agent flow gap X1 between the top surface of the protrusion 5x and the outer surface of the upper plate portion 2a of the molded substrate 2 (temporary mold clamping step).

[0086] In that state, as shown in Figure 6(a), liquid coating agent 4 is injected into the coating gap X1, and the liquid coating agent 4 flowing through the coating gap C2 is passed through the coating agent flow gap X1 and flows from one side of the protrusion 5x to the other side (injection step).

[0087] Subsequently, as shown in Figure 6(b), the first mold 1 is brought closer to the second mold 3 to reduce the coating agent flow gap X1 (to zero in this modified embodiment), and at least a portion (all in this modified embodiment) of the liquid coating agent 4 present in the coating agent flow gap X1 is removed from the coating agent flow gap X1 (secondary mold clamping step). In this modified embodiment, since the coating agent flow gap X1 is zero, the coating gap C2 between the outer surface of the upper plate portion 2a of the molded substrate 2 and the inner surface of the cavity 3a of the second mold 3 becomes equal to the height H of the protrusion 5x.

[0088] This modified embodiment has the same components (flange portion, overflow passage, viscosity of liquid coating agent, etc.) as the first embodiment described above, except that a protrusion 5 is pre-formed on the inner surface of the cavity 3a of the second mold 3, and the upper surface of the upper plate portion 2a of the molded substrate 2 is a flat surface. Therefore, it can be considered technically equivalent to the first embodiment. Thus, the modified embodiment also produces the same functions and effects as the embodiment described above.

[0089] Although preferred embodiments of the present invention have been described above with reference to the attached drawings, it goes without saying that the present invention is not limited to the embodiments described above, and that various modifications or alterations within the scope of the claims also fall within the technical scope of the present invention. [Industrial applicability]

[0090] The present invention relates to a method and apparatus for manufacturing molded products with in-mold coating, in which a coating gap is formed between the outer surface of a molded substrate housed inside a mold and the inner surface of the mold, and a liquid coating agent is injected into the coating gap to form a coating film on the outer surface of the molded substrate. The present invention can be used in a method and apparatus for manufacturing molded products with in-mold coating that allows for the formation of protrusions according to a desired pattern on the outer surface of the molded substrate in advance, and for the coating film to be appropriately formed on the outer surface of the molded substrate excluding the protrusions.

[0091] 1. First mold 1a core 1c Buttock surface 2 Molding base material 3. Second mold 3a Cavity 3c Buttock surface 4. Liquid coating agent 5. Convex part 6. Flange section 9 Injection passage 10 Flange housing recess 11 Overflow path C1 Coating gap (the space between the side surface of the molded substrate and the side surface of the cavity) C2 Coating gap (the space between the top surface of the molded substrate and the top surface of the cavity) X1 Coating agent flow gap (first flow gap) X2 Nose gap X3 Amount of deflection in the flange section S1 Clamping execution stroke

Claims

1. A method for manufacturing an in-mold coated molded product, comprising: mounting a molded substrate in a first mold; covering the molded substrate with a second mold to form a coating gap between the inner surface of the second mold and the outer surface of the molded substrate; and injecting a liquid coating agent into the coating gap to adhere to the outer surface of the molded substrate, The molded substrate is pre-formed with protrusions corresponding to a desired pattern on its outer surface, and the molded substrate with the protrusions formed thereon is mounted into the first mold. The molded substrate mounted in the first mold is covered with the second mold, forming the coating gap between the outer surface of the molded substrate other than the protrusion and the inner surface of the second mold, and forming a coating agent flow gap between the top surface of the protrusion and the inner surface of the second mold. In that state, the liquid coating agent is injected into the coating gap, and the liquid coating agent flowing through the coating gap is passed through the coating agent flow gap and flows from one side of the protrusion to the other side. A method for manufacturing a molded product with in-mold coating, characterized by subsequently bringing the second mold and the first mold closer together to reduce the coating agent flow gap, and removing at least a portion of the liquid coating agent present in the coating agent flow gap from the coating agent flow gap.

2. A method for manufacturing an in-mold coated molded product, comprising: mounting a molded substrate in a first mold; covering the molded substrate with a second mold to form a coating gap between the inner surface of the second mold and the outer surface of the molded substrate; and injecting a liquid coating agent into the coating gap to adhere to the outer surface of the molded substrate, The inner surface of the second mold is pre-formed with protrusions corresponding to a desired pattern, and the molded substrate is mounted in the first mold. The molded substrate mounted in the first mold is covered with the second mold, forming the coating gap between the inner surface of the second mold other than the protrusion and the outer surface of the molded substrate, and forming a coating agent flow gap between the top surface of the protrusion and the outer surface of the molded substrate. In that state, the liquid coating agent is injected into the coating gap, and the liquid coating agent flowing through the coating gap is passed through the coating agent flow gap and flows from one side of the protrusion to the other side. A method for manufacturing a molded product with in-mold coating, characterized by subsequently bringing the second mold and the first mold closer together to reduce the coating agent flow gap, and removing at least a portion of the liquid coating agent present in the coating agent flow gap from the coating agent flow gap.

3. A flange portion is formed in advance on the molded substrate, and the molded substrate with the flange portion formed thereon is mounted on the first mold. When forming the coating agent flow gap, The method for manufacturing a molded product with in-mold coating according to claim 1 or 2, characterized in that the liquid coating agent flowing in the coating gap is prevented from leaking out from between the second mold and the molded substrate by pressing the second mold against the flange, and the coating agent flow gap is made the first flow gap.

4. When the second mold and the first mold are brought closer together to reduce the coating agent flow gap, and at least a portion of the liquid coating agent present in the coating agent flow gap is removed from the coating agent flow gap, The method for manufacturing a molded product with in-mold coating according to claim 3, characterized in that by bringing the second mold and the first mold together, the flange portion is pressed and compressed by the second mold, and the coating agent flow gap is set to a second flow gap that is narrower than the first flow gap, or to zero.

5. When the second mold and the first mold are brought closer together to reduce the coating agent flow gap, and at least a portion of the liquid coating agent present in the coating agent flow gap is removed from the coating agent flow gap, A method for manufacturing a molded product with in-mold coating according to claim 1 or 2, characterized in that a portion of the liquid coating agent flowing within the coating gap is discharged from an overflow passage formed in the second mold.

6. The method for manufacturing a molded product with in-mold coating according to claim 1 or 2, characterized in that the convex portion has an enclosed shape in which the inside is surrounded with respect to the flow of the liquid coating agent.

7. The method for manufacturing a molded product with in-mold coating according to claim 1 or 2, characterized in that the liquid coating agent is a thermosetting resin.

8. The method for manufacturing a molded product with in-mold coating according to claim 7, characterized in that the viscosity of the thermosetting resin is 1 mPa·s or more and 50 Pa·s or less before it is injected into the coating gap.

9. A manufacturing apparatus used in the method for manufacturing a molded product with in-mold coating as described in claim 4, A manufacturing apparatus for molded products with in-mold coating, characterized in that an actuator for clamping and opening the mold by moving the first mold and the second mold closer together and further apart is equipped with a control unit for adjusting the clamping stroke.

10. A manufacturing apparatus used in the method for manufacturing a molded product with in-mold coating as described in claim 4, A manufacturing apparatus for molded products with in-mold coating, characterized in that an actuator for clamping and opening the mold by moving the first mold and the second mold closer together and further apart is equipped with a control unit for adjusting the clamping force.

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