In-mold coating injection device and in-mold coating injection method using same

Abstract

[Problem] To provide an in-mold coating injection device that reduces the heat received from a mold by a thermosetting liquid coating agent before injection into the mold from an injector, suppresses a hardening reaction to prevent the occurrence of contamination, and achieves a stable injection state. [Solution] An in-mold coating injection device 1 that injects a thermosetting liquid coating agent 4 into a coating gap 13 that is between an outer surface of a molding material 3 that is held inside heated upper and lower molds 2a, 2b and an inner surface of the upper mold 2b comprises: an injector 8 that is for spraying the thermosetting liquid coating agent 4 into the coating gap 13 from an injection port 6 and includes, at a tip end part 8a, the injection port 6 and a tip end valve part 7d of an opening / closing valve 7 that opens / closes the injection port 6; and a heat insulation layer 9 that is provided between the tip end part 8a of the injector 8 and the upper mold 2b and comprises a material that has a lower thermal conductivity than the material of the tip end part 8a.

Description

In-mold coating injection device and in-mold coating injection method using the same

[0001] The present invention relates to an in-mold coating injection device that injects a thermosetting liquid coating agent between a substrate held inside a heated mold and the inner surface of the mold, and an in-mold coating injection method using the same.

[0002] With growing interest in environmental issues in recent years, in-mold coating (IMC) has attracted attention as an alternative to painting that does not use organic solvents and is highly effective in reducing CO2 emissions. IMC is a technique in which one mold holds a molded substrate and another mold is pressed against it so as to cover the molded substrate, a liquid coating agent is injected into the coating gap between the inner surface of the other mold and the outer surface of the molded substrate, and the liquid coating agent is solidified by heating to form a coating on the outer surface of the molded substrate.

[0003] The features of IMC include: (1) it is gentle on the environment and humans because it does not use the organic solvents used in general spray painting, (2) it does not require equipment for the painting process (spraying, oven heat treatment), and (3) because the paint is not diluted with organic solvents, the rate at which the material (paint) before application is formed as a coating on the outer surface of the molded substrate (coating efficiency) is very high, resulting in very little waste. IMC is used to improve the quality of molded product surfaces and simplify the painting process, and is widely used for exterior parts, especially in the automotive industry, which has high demands for appearance and quality.

[0004] In order to impart functional properties lacking in the material (e.g., thermoplastic resin) of the substrate to be coated, the liquid coating agent often uses a thermosetting resin containing a variety of non-resinous substances (e.g., finely divided metals or inorganic substances) with various functional properties. In such a thermosetting liquid coating agent, the thermosetting resin as the main component hardens through a chemical reaction caused by the heat of the mold, and the coating is applied to the outer surface of the substrate. Known in-mold coating injection devices for injecting such a thermosetting liquid coating agent into a mold containing the substrate to be coated are shown in Figures 1(a), 1(b), 1(c), and 1(d) (see Patent Document 1).

[0005] As shown in FIG. 1( a), this in-mold coating injection device a butts one mold b against the other mold c to form a molding space f between a cavity d and a core e, and as shown in FIG. 1( b), injects a molding material h (e.g., a thermoplastic resin) from a sprue g into the molding space f to form a molding substrate i. Immediately thereafter, as shown in FIG. 1( c), injects a thermosetting liquid coating agent j as a coating agent into the inner surface of the cavity d at a predetermined pressure, and as shown in FIG. 1( d), the injected thermosetting liquid coating agent j penetrates between the inner surface of the cavity d and the outer surface of the molding substrate i and hardens, forming a coating on the outer surface of the molding substrate i.

[0006] 1A, this in-mold coating injection device a has a cylinder k provided in one mold b so as to be connected to the inner surface of a cavity d, a rod-shaped piston l that freely rises and falls inside the cylinder k, and a hydraulic actuator m that raises and lowers the rod-shaped piston l. The in-mold coating injection device a also has a reservoir n partitioned so as to be connected to the top of the cylinder k, an inlet path o that introduces a thermosetting liquid coating agent j as a coating material into the reservoir n, a discharge path p that discharges the thermosetting liquid coating agent j from the reservoir n, and an external circulation line (not shown) that connects the discharge path o and the inlet path p. The thermosetting liquid coating agent j in the discharge path p is returned to the inlet path o via the circulation line to circulate the thermosetting liquid coating agent j in the reservoir n, thereby preventing the thermosetting liquid coating agent j in the reservoir n from hardening due to heat from the mold b.

[0007] The molding process and coating process for the substrate i using this in-mold coating injection device a will now be described. First, as shown in Figure 1(a), the rod-shaped piston l is lowered to a position where its lower end surface is flush with the cavity d, and a portion of the molding space f is defined by the lower end surface of the rod-shaped piston l. In this state, as shown in Figure 1(b), a molding material h (e.g., a thermoplastic resin) is injected into the molding space f from the sprue g to form the substrate i. The substrate i receives heat from the mold b, which is heated to a high temperature, and maintains its plasticity (soft state) for a certain period of time.

[0008] Immediately after molding the substrate i, as shown in Figure 1(c), the rod-shaped piston l is raised to above the reservoir n, and the thermosetting liquid coating agent j introduced into the reservoir n from the introduction path o is introduced into the cylinder k. As shown in Figure 1(d), the rod-shaped piston l is lowered, and the thermosetting liquid coating agent j in the cylinder k is injected at a predetermined pressure between the inner surface of the cavity d and the outer surface of the substrate i. The injected thermosetting liquid coating agent j penetrates between the inner surface of the cavity d and the outer surface of the substrate i and hardens through a chemical reaction caused by the heat of the mold b, forming a coating on the outer surface of the substrate i.

[0009] Patent No. 3422843

[0010] In the above-mentioned conventional in-mold coating injection device a, as shown in Figures 1(a) to 1(d), a rod-shaped piston l moves up and down inside a cylinder k to inject a thermosetting liquid coating agent j into a cavity d of a mold b, so an extremely narrow clearance (gap) is required between the cylinder k and the rod-shaped piston l to allow sliding between them.

[0011] 1(a) and 1(b), when the rod-shaped piston l is lowered and inserted into the cylinder k, a very small amount of the thermosetting liquid coating agent j in the reservoir n penetrates into the clearance between the cylinder k and the rod-shaped piston l and hardens due to the heat of the mold b, which has been heated to a high temperature. As a result, a hardened layer of the hardened thermosetting liquid coating agent j is formed in the clearance between the cylinder k and the rod-shaped piston l. This hardened layer adheres to the inner surface of the cylinder k or the outer surface of the rod-shaped piston l.

[0012] If a cured layer of the thermosetting liquid coating agent j formed in the clearance between the cylinder k and the rod-shaped piston l adheres to the inner surface of the cylinder k, the rod-shaped piston l is raised as shown in Figure 1(c) and then lowered as shown in Figure 1(d), whereupon the edge of the lower end surface of the rod-shaped piston l scrapes off the cured layer, and pieces of the scraped-off cured layer get between the cavity d and the molding substrate i and become contaminants (impurities, foreign matter). If pieces of the cured layer appear on the surface of the product, the appearance will be poor, and if pieces of the cured layer are present at the interface between the molding substrate and the coating, they will act as starting points for interfacial peeling, inhibiting adhesion and resulting in a defective product.

[0013] If a hardened layer of the thermosetting liquid coating agent j formed in the clearance between the cylinder k and the rod-shaped piston l adheres to the outer surface of the rod-shaped piston l, this hardened layer is scraped off by the edge of the guide hole q formed in the ceiling surface of the reservoir chamber n to guide the rod-shaped piston l when the rod-shaped piston l, which is in a lowered state as shown in Figure 1(b), is raised as shown in Figure 1(c), and pieces of the scraped-off hardened layer are mixed into the thermosetting liquid coating agent j in the reservoir chamber n. These scraped-off pieces of the hardened layer are discharged from the reservoir chamber n via the discharge path p together with the thermosetting liquid coating agent j, mix into an external circulation line (not shown), and return to the reservoir chamber n through the introduction path o, so that the thermosetting liquid coating agent j mixed with the scraped-off pieces of the hardened layer will circulate thereafter. As shown in Figure 1(d), the scraped-off pieces of the hardened layer in the reservoir chamber n are injected into the space between the cavity d and the molding substrate i together with the thermosetting liquid coating agent j as the rod-shaped piston l descends, causing the problem described in the previous paragraph.

[0014] The object of the present invention, which was devised in consideration of the above circumstances, is to provide an in-mold coating injection device and an in-mold coating injection method using the same that injects a thermosetting liquid coating agent between the outer surface of a molding substrate held inside a heated mold and the inner surface of the mold, which reduces the heat that the thermosetting liquid coating agent receives from the mold before being injected from the injection device into the mold, suppresses the curing reaction, thereby preventing the occurrence of contamination and achieving a stable injection state.

[0015] According to the present invention, which has been devised to achieve the above-mentioned object, there is provided an in-mold coating injection device that injects a thermosetting liquid coating agent between the outer surface of a substrate to be molded held inside a heated mold and the inner surface of the mold, the in-mold coating injection device comprising: an injection machine having an injection port at its tip and an on-off valve for opening and closing the injection port, and for injecting the thermosetting liquid coating agent sprayed from the injection port between the outer surface of the substrate to be molded and the inner surface of the mold; and a heat insulating layer that is provided between the tip of the injection machine and the mold and is made of a material with a thermal conductivity lower than that of the material of the tip.

[0016] In the in-mold coating injection device according to the present invention, the injection machine may be provided with a cooling mechanism to prevent the thermosetting liquid coating agent inside the injection machine from hardening.

[0017] In the in-mold coating injection device according to the present invention, the tip of the injection machine has an outer peripheral surface that is inserted into a mounting hole formed in the mold and a tip surface on which an injection port is provided, and an insulating layer may be provided on the outer peripheral surface of the tip so as to be in contact with the inner peripheral surface of the mounting hole.

[0018] In the in-mold coating injection device according to the present invention, the thermal conductivity of the heat insulating layer may be lower than the thermal conductivity of the mold.

[0019] In the in-mold coating injection device according to the present invention, the heat insulating layer may be a thermal sprayed layer.

[0020] In the in-mold coating injection device according to the present invention, the thermal sprayed layer may be a ceramic thermal sprayed layer formed by thermally spraying ceramic.

[0021] In the in-mold coating injection device of the present invention, a flange portion is provided on the outer peripheral surface of the tip of the injection machine, positioned closer to the tip surface than the insulating layer provided on the outer peripheral surface, and the outer diameter of the edge of the flange portion is smaller than the outer diameter of the surface of the insulating layer, and a gap may be formed between the edge of the flange portion and the mounting hole of the mold.

[0022] In the in-mold coating injection device according to the present invention, the heat insulating layer may be porous.

[0023] Furthermore, according to the present invention, there is provided an in-mold coating injection method for injecting a thermosetting liquid coating agent between the outer surface of a molding substrate and the inner surface of a mold using the above-mentioned in-mold coating injection device, characterized in that heat from the mold is transmitted to the tip of the injection machine through the heat insulating layer, thereby suppressing heat transfer from the mold to the tip of the injection machine and suppressing the curing reaction of the thermosetting liquid coating agent near the injection port arranged at the tip of the injection machine and the on-off valve that opens and closes the injection port.

[0024] Furthermore, according to the present invention, there is provided an in-mold coating injection method for injecting a thermosetting liquid coating agent between the outer surface of a molding substrate and the inner surface of a mold using the above-mentioned in-mold coating injection device, characterized in that a portion of the thermosetting liquid coating agent sprayed from the injection port of the injection machine enters the gap between the mounting hole of the mold and the edge of the flange portion of the injection machine, and the thermosetting liquid coating agent that has entered the gap is cured by the heat from the mold, thereby preventing the thermosetting liquid coating agent sprayed from the injection port from penetrating through the gap into the heat insulating layer.

[0025] The in-mold coating injection device and in-mold coating injection method using the same according to the present invention can achieve the following effects: (1) In an in-mold coating injection device that injects a thermosetting liquid coating agent between the outer surface of a substrate held inside a heated mold and the inner surface of the mold, the device includes an injection machine having an injection port at its tip and an on-off valve that opens and closes the injection port, for injecting the thermosetting liquid coating agent sprayed from the injection port between the outer surface of the substrate and the inner surface of the mold, and an insulating layer that is disposed between the tip of the injection machine and the mold and is made of a material with a lower thermal conductivity than the material of the tip. This allows heat from the mold to be transferred to the tip of the injection machine through the insulating layer, thereby suppressing heat transfer from the mold to the tip of the injection machine, thereby reducing the heat that the thermosetting liquid coating agent receives from the mold in the vicinity of the injection port disposed at the tip and the on-off valve that opens and closes the injection port. (2) As a result, the curing reaction of the thermosetting liquid coating agent near the injection port of the injection machine and the valve that opens and closes the injection port, i.e., the curing reaction of the thermosetting liquid coating agent before injection, is suppressed, preventing the occurrence of contamination and achieving a stable injection state.

[0026] 1 is an explanatory diagram of a conventional in-mold coating injection device and an in-mold coating injection method using the same, where (a) shows a process before molding a molding substrate, (b) shows the molding process of a molding substrate, (c) shows a process before injecting a coating agent, and (d) shows the coating agent injection process.

[0023] FIG. 1 is a cross-sectional view showing the entire system of an in-mold coating injection device according to one embodiment of the present invention.

[0024] FIG. 2 is a cross-sectional view showing an injection port, an on-off valve, and a heat insulating layer at the tip of the injection machine of the in-mold coating injection device of FIG. 2.

[0025] FIG. 1 is an explanatory view showing a cooling mechanism provided in the injection machine of the in-mold coating injection device of FIG. 2, where (a) is a perspective view and (b) is a cross-sectional view.

[0026] FIG. 2 is a cross-sectional view showing the injection machine of the in-mold coating injection device of FIG. 2 when the thermosetting liquid coating agent begins to be filled into the injection machine.

[0027] FIG. 1 is a cross-sectional view following FIG. 5 when the injection of the thermosetting liquid coating agent into the injection machine is completed.

[0028] FIG. 1 is a cross-sectional view following FIG. 6 when the thermosetting liquid coating agent filled in the injection machine begins to be injected from the injection port between the outer surface of the molding substrate and the inner surface of the mold. 9(a) is a cross-sectional view showing the end of the in-mold coating injection device according to the modified example, (b) is a cross-sectional view showing the curable liquid coating agent that has entered the gap between the edge of the flange portion provided at the end and the mounting hole of the mold and has been cured by heat from the mold, and (c) is a partially enlarged view of (b). 9(a) is a cross-sectional view showing the manufacturing process of the flange portion and the heat insulating layer at the end of the injection device according to the modified example shown in FIG. 9(a), (b) is a cross-sectional view showing the first step, (c) is a cross-sectional view showing the second step, and (c) is a cross-sectional view showing the third step.

[0027] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Dimensions, materials, and other specific values ​​shown in the embodiments are merely examples for facilitating understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0028] 2, an in-mold coating injection device 1 according to one embodiment of the present invention injects a thermosetting liquid coating agent 4 between the outer surface of a molding substrate 3 held inside a heated mold 2 and the inner surface of the mold 2. This in-mold coating injection device 1 is equipped with an injector 8 having an injection port 6 at its tip 8a and an on-off valve 7 (tip valve portion 7d) for opening and closing the injection port 6, and for injecting the thermosetting liquid coating agent 4 sprayed from the injection port 6 between the outer surface of the molding substrate 3 and the inner surface of the mold 2, and an insulating layer 9 provided between the tip 8a of the injector 8 and the mold 2, the insulating layer 9 being made of a material with a thermal conductivity lower than that of the material of the tip 8a.

[0029] As shown in Figures 3 and 4, the injector 8 is provided with a cooling mechanism 10 to prevent the thermosetting liquid coating agent 4 inside the injector 8 from hardening. The tip 8a of the injector 8 has an outer peripheral surface 8x that is inserted into the tip hole portion 11a of the mounting hole 11 formed in the mold 2, and a tip surface 8y where the injection port 6 is provided. A heat insulating layer 9 is provided on the outer peripheral surface 8x of the tip 8a so as to contact the inner peripheral surface of the mounting hole 11. The thermal conductivity of the heat insulating layer 9 is lower than that of the material of the mold 2, and the heat insulating layer 9 is made of a sprayed layer. A ceramic sprayed layer formed by spraying ceramic is used as the heat insulating layer 9. Each component will be described below.

[0030] 2, the mold 2 is composed of one mold 2a (hereinafter also referred to as the lower mold 2a) provided with a convex core 12 on which a separately molded molding substrate 3 is attached, and the other mold 2b (hereinafter also referred to as the upper mold 2b) disposed opposite the first mold 2a and having a recessed cavity 14 so as to form a predetermined coating gap 13 (e.g., 50 μm to 100 μm) between the outer surface of the molding substrate 3 attached to the core 12 of the lower mold 2a. The upper mold 2b is attached to the lower surface of an upper platen 15 via a heat insulating plate 16 with bolts (not shown), and the lower mold 2a is attached to the upper surface of a lower platen 17 with bolts (not shown). As the lower platen 17 moves vertically relative to the upper platen 15, the lower mold 2a moves closer to and away from the upper mold 2b, thereby clamping and opening the molds.

[0031] As shown in Figures 2 and 5, a runner groove 18 is formed on the mating surface (parting surface) of the upper mold 2b with the lower mold 2a to supply a thermosetting liquid coating agent 4 (e.g., a one-component curing thermosetting paint, hereinafter simply referred to as paint) to a coating gap 13 between the outer surface of the molding substrate 3 and the inner surface of the cavity 14 of the upper mold 2b when the molds are clamped. The runner groove 18 contains a runner 3a generated when the molding substrate 3 is molded using a separate molding die (not shown) instead of the upper mold 2b. As shown in Figures 7 and 8, the paint 4 is sprayed from the injection port 6 of the injection machine 8, passes through the runner groove 18, and is injected into the coating gap 13 along the runner 3a.

[0032] As shown in FIGS. 2 and 5 , the upper mold 2b is provided with a heating mechanism 19 for heating and curing the coating material 4 injected into the coating gap 13 through the runner groove 18. The heating mechanism 19 uses, for example, an electric heating wire (electric resistance wire) that generates heat when electricity is applied. The heating mechanism 19 (electric heating wire) is disposed near the ceiling surface of the cavity 14 that defines the coating gap 13. A heating mechanism 19 is also provided for the lower mold 2a. The heating mechanism 19 for the lower mold 2a prevents the upper mold 2b from being cooled by the lower mold 2a when the lower mold 2a is clamped against the upper mold 2b, thereby suppressing a drop in temperature in the coating gap 13. In addition, an insulating plate 16 interposed between the upper mold 2b and the upper platen 15 functions to prevent heat from the upper mold 2b from being transferred to the upper platen 15. This reduces the heat input from the upper platen 15 to the injection machine 8, thereby suppressing the progress of the curing reaction of the coating material 4 introduced into the injection machine 8.

[0033] (Injection Machine 8) As shown in Figures 2 and 5, when the lower mold 2a, with the molding substrate 3 held by the core 12, is pressed against the upper mold 2b, a predetermined coating gap 13 (e.g., 50 μm to 100 μm) is formed between the inner surface of the cavity 14 of the upper mold 2b and the outer surface of the molding substrate 3. An injection machine 8 is attached to the upper mold 2b to inject a predetermined amount of paint 4 into the coating gap 13 that corresponds to the volume of that space. A tip 8a of the injection machine 8 is provided with an injection port 6 for injecting the paint 4 into the coating gap 13 and an on-off valve 7 (tip valve portion 7d) for opening and closing the injection port 6. The tip 8a of the injection machine 8 has an outer peripheral surface 8x that is inserted into a tip hole portion 11a of a mounting hole 11 formed in the upper mold 2b, and a tip surface 8y on which the injection port 6 is provided. A heat insulating layer 9 is provided on the outer peripheral surface 8x of the tip portion 8a so as to be in contact with the inner peripheral surface of the tip hole portion 11a of the mounting hole 11.

[0034] As shown in FIG. 2 , the injection mold 8 has a three-stage cylindrical body, with a small-diameter tip portion 8a, a larger-diameter medium-diameter portion 8b, and an even larger-diameter portion 8c connected from bottom to top. A mounting flange 20 is provided on the outer periphery of the large-diameter portion 8c. The mounting flange 20 is attached to the upper platen 15 with bolts 21. As shown in FIG. 5 , the upper mold 2b has a mounting hole 11 formed therethrough, penetrating the top and bottom surfaces, for accommodating the injection mold 8. The mounting hole 11 includes a tip portion 11a having a diameter corresponding to the tip portion 8a of the injection mold 8 and a medium-diameter portion 11b having a diameter larger than that of the medium-diameter portion 8b of the injection mold 8. The tip portion 11a is connected to the runner groove 18 via a coating agent reservoir 26. A predetermined gap 22 is formed between the medium-diameter portion 11b and the medium-diameter portion 8b. The gap 22 functions as an insulating air barrier to prevent heat from the upper mold 2b from being transferred to the injection mold 8.

[0035] 5, a through-hole 23 having a diameter larger than that of the large-diameter portion 8c of the casting machine 8 is formed in the upper platen 15 to accommodate the large-diameter portion 8c of the casting machine 8. A gap 24 is formed between the through-hole 23 and the large-diameter portion 8c of the casting machine 8, and the gap 24 functions as an air insulating layer that prevents the heat, even if small, that is transferred from the upper mold 2b to the upper platen 15 via the insulating plate 16 from being transferred to the casting machine 8.

[0036] 5, an insulating ring 25 that prevents heat from the upper mold 2b from being transmitted to the injection machine 8 is interposed between the step from the large diameter portion 8c to the medium diameter portion 8b of the injection machine 8 and the upper surface of the upper mold 2b. The insulating ring 25 prevents heat from being transmitted from the upper mold 2b to the injection machine 8, thereby preventing the paint 4 introduced into the injection machine 8 from being exposed to heat from the upper mold 2b and progressing in a curing reaction. When the bolt 21 is screwed in, the insulating ring 25 is sandwiched between the lower surface of the large diameter portion 8c and the upper surface of the upper mold 2b and is slightly crushed. The force of this restoration presses the male thread portion of the bolt 21 and the female thread portion of the screw hole for the bolt 21 formed in the upper platen 15 against each other in the axial direction, so that the insulating ring 25 also functions as a locking material for the bolt 21.

[0037] 3 and 5, the tip 8a of the injection machine 8 is provided with the injection port 6 for injecting the paint 4 and the tip valve portion 7d of the on-off valve 7 for opening and closing the injection port 6. The tip 8a of the injection machine 8 has an outer peripheral surface 8x that is inserted into the tip hole portion 11a of the mounting hole 11 formed in the upper mold 2b, and a tip surface 8y provided with the injection port 6. A stepped surface 8z with a slightly smaller diameter is formed on the outer peripheral surface 8x, and the insulating layer 9 is provided on the stepped surface 8z so as to come into contact with the tip hole portion 11a of the mounting hole 11. The insulating layer 9 is made of a material with a lower thermal conductivity than the material of the tip 8a of the injector 8, and prevents heat from the upper mold 2b from being transferred to the tip 8a of the injector 8, reducing the heat received from the upper mold 2b by the paint 4 (thermosetting liquid coating agent) near the injection port 6 and the tip valve portion 7d of the on-off valve 7 of the injector 8, both of which are provided at the tip 8a of the injector 8. This suppresses the curing reaction of the paint 4 near the injection port 6 of the injector 8 and the tip valve portion 7d of the on-off valve 7, i.e., the curing reaction of the paint 4 before (immediately before) injection, preventing the hardened paint 4 from becoming contaminants (impurities, foreign matter) and being injected into the coating gap 13, and achieving a stable injection state.

[0038] (Ceramic as Material for Heat Insulating Layer 9) The thermal conductivity of the heat insulating layer 9 shown in Figures 3 and 5 is lower than that of the material of the tip 8a of the injection mold 8 and is lower than that of the material of the mold 2 (upper mold 2b, lower mold 2a). For example, if the material of the injection mold 8 including the tip 8a, and the materials of the upper mold 2b and lower mold 2a are iron-based metals (steel, cast iron, etc.), the material of the heat insulating layer 9 is ceramic, which has a lower thermal conductivity than iron-based metals. Examples of ceramics include zirconia, steatite, cordierite, forsterite, yttria, cermet, silicon nitride, and alumina. For example, the thermal conductivity of zirconia alone is 3 W / m·K, which is approximately 1 / 10 of the thermal conductivity (25 to 30 W / m·K) of iron-based metals (steel, cast iron, etc.). Therefore, when zirconia is used as the material for the insulating layer 9, the heat input from the upper mold 2b to the tip 8a of the injection machine 8 can be reduced to approximately 1 / 10 compared to when the insulating layer 9 does not exist (when the tip hole 11a of the mounting hole 11 formed in the upper mold 2b and the tip 8a of the injection machine 8 are in direct contact).

[0039] Instead of ceramic, the thermal insulation layer 9 shown in Figures 3 and 5 could be made of GFRP, a material made of glass fiber with added epoxy resin or phenolic resin. GFRP has a thermal conductivity of 0.5 to 1.0 W / m·K, which is significantly lower than the thermal conductivity of iron-based metals (25 to 30 W / m·K), making it more advantageous than ceramic in terms of thermal insulation. However, if GFRP is used for the thermal insulation layer 9, the adhesion of the paint 4 sprayed from the injection port 6 into the coating agent reservoir 26 below is considered. The glass fibers on the GFRP create minute irregularities on the surface, creating a large contact area with the paint, creating a wedge effect. This makes it easier for the paint 4 sprayed from the injection port 6 into the coating agent reservoir 26 to adhere to the end surface of the GFRP thermal insulation layer 9. 8, after the injection of the coating material 4 into the coating gap 13 is completed, when the lower mold 2a is separated from the upper mold 2b to remove the molding substrate 3 (product) coated with the coating material 4, the coating material 4 in the coating agent reservoir 26 may adhere to the end face of the heat insulating layer 9 made of GFRP, making it difficult to remove the product from the mold. Therefore, it cannot be said that using GFRP as the material for the heat insulating layer 9 is appropriate.

[0040] It is also conceivable to use an olefin-based resin such as polypropylene / polyethylene or a fluorine-based resin (such as Teflon®) as the material for the insulating layer 9 shown in Figure 8, which has poor chemical adhesion to the paint 4 sprayed from the injection port 6 into the coating agent reservoir 26 below. However, olefin-based resins have low heat resistance and cannot be used for the insulating layer 9. That is, the paint 4 (thermosetting liquid coating agent) sprayed from the injection port 6 into the coating agent reservoir 26 reaches a temperature (e.g., approximately 100°C) that properly cures the thermosetting coating agent. Considering this temperature, it is not advisable to use an olefin-based resin with low heat resistance for the insulating layer 9. Furthermore, Teflon® lacks rigidity, making it difficult to achieve processing precision of several microns, and therefore, if used for the insulating layer 9, paint leakage cannot be prevented. That is, the heat insulating layer 9 also functions as a packing that prevents the paint 4 sprayed from the injection port 6 of the tip 8a of the injector 8 into the coating agent reservoir 26 from leaking upward from between the tip 8a and the tip hole 11a, but Teflon (registered trademark) is difficult to process with the required precision due to its lack of rigidity, and there is a possibility that it may not function properly as a packing, so it is not advisable to use it for the heat insulating layer 9. Based on the above considerations, in this embodiment, ceramic is used as the material for the heat insulating layer 9.

[0041] (Ceramic spray layer as thermal insulation material 9) The thermal insulation layer 9 shown in Figures 3 and 5 is a ceramic spray layer formed by thermally spraying a ceramic such as zirconia, as described above. The ceramic spray layer 9 is formed by spraying a ceramic such as zirconia onto the stepped surface 8z of the outer peripheral surface 8x of the tip portion 8a of the injector 8 to a thickness slightly thicker than the specified dimension (the diameter of the tip hole portion 11a of the mounting hole 11), and then polishing (cutting) it to the specified dimension. This allows the thickness of the thermal insulation layer 9 (ceramic spray layer) to be made as thin as possible. In this embodiment, the thickness of the ceramic spray layer 9 is approximately 0.3 mm.

[0042] On the other hand, it is also possible to form a ceramic sleeve and attach it to the tip 8a of the injector 8 to form the insulating layer 9, but because strength and rigidity issues require that the ceramic sleeve be made thick to a certain extent, the thickness of the ceramic sleeve serving as the insulating layer 9 would be much thicker than a ceramic sprayed layer. As a result, when the tip 8a of the injector 8 with the ceramic sleeve attached is inserted into the tip hole 11a of the mounting hole 11 formed in the upper mold 2b, the diameter of the tip hole 11a becomes larger, increasing the volume of the coating agent reservoir 26. As a result, the paint 4 that has hardened in the coating agent reservoir 26 will form clumps and be discarded, reducing the material yield.

[0043] In this embodiment, by using a ceramic sprayed layer as the insulating layer 9, the inner diameter of the tip hole 11a of the mounting hole 11 formed for inserting the tip 8a of the injection mold 8 into the upper mold 2b can be made as small as possible compared to when a ceramic sleeve is used. Therefore, the volume of the coating agent reservoir 26 defined by the tip surface 8y (lower surface) of the tip 8a of the injection mold 8, the inner circumferential surface of the tip hole 11a of the mounting hole 11, and the lower mold 2a can be made small. The coating agent reservoir 26 is connected to the runner groove 18, and the paint 4 hardened in the coating agent reservoir 26 is removed (cut off) from the molding substrate 3 (product) coated with the paint 4 together with the runner hardened in the runner groove 18 in a subsequent process. Therefore, by reducing the volume of the coating agent reservoir 26, the amount of paint 4 discarded according to the volume of the coating agent reservoir 26 is reduced, improving the material yield of the paint 4.

[0044] 3 and 5, in this embodiment, the thermal insulating layer 9 (ceramic sprayed layer) is formed on a stepped surface 8z that is slightly smaller than the outer peripheral surface 8x of the tip end 8a of the injector 8. Therefore, compared to when the ceramic sprayed layer 9 is formed directly on the outer peripheral surface 8x of the tip end 8a of the injector 8 (when the stepped surface 8z does not exist), the inner diameter of the tip end hole 11a of the mounting hole 11 can be reduced by the dimension of the step between the stepped surface 8z and the outer peripheral surface 8x. This reduces the volume of the coating agent reservoir 26, reduces the amount of paint 4 discarded in accordance with the volume of the coating agent reservoir 26, and improves the material yield of the paint 4.

[0045] (Measuring Cylinder 27, Piston 28) As shown in FIG. 5 , a measuring cylinder 27 for containing a predetermined amount of paint 4 is formed inside the injector 8. The measuring cylinder 27 is formed inside the large-diameter portion 8c of the injector 8, and is positioned inside the injector 8 at a position least affected by the heat of the upper mold 2b due to the above-mentioned insulating layer 9, insulating ring 25, gap 22 (air insulating layer), and gap 24 (air insulating layer). In this embodiment, the metering cylinder 27 is positioned above the upper surface of the upper mold 2b and above the insulating ring 25. A piston 28 is provided inside the metering cylinder 27 so as to be movable axially (up and down). The piston 28 includes a piston main body 28a having a diameter that slides along the metering cylinder 27, and a piston protrusion 28b provided on the portion of the piston main body 28a that protrudes from the metering cylinder 27 above the piston main body 28a.

[0046] (Inlet 6) As shown in Figures 5 and 9, a passage hole 29 with a smaller diameter than the metering cylinder 27 is formed inside the medium-diameter section 8b and tip section 8a of the injector 8 shown in Figure 2, connected to the metering cylinder 27 and facing downward. A conical valve seat 30 is formed at the lower end of the passage hole 29, and the inlet 6 is formed at the lower end of the valve seat 30 so as to communicate with the coating agent reservoir 26. The inlet 6 is closed when the tip valve portion 7d at the lower end of the on-off valve 7 is seated on the valve seat 30, and is opened when the tip valve portion 7d at the lower end of the on-off valve 7 is separated from the valve seat 30. When the valve is opened, the coating material 4 in the metering cylinder 27 is injected from the inlet 6 through the passage hole 29 into the coating agent reservoir 26, and from the coating agent reservoir 26 through the runner groove 18 into the coating gap 13.

[0047] (Supply Passage 32) As shown in Figure 5, a supply port 31 for supplying paint 4 to the metering cylinder 27 is provided on the side of the large-diameter portion 8c of the injector 8 and is connected to the metering cylinder 27. A supply passage 32 for supplying paint 4 to the metering cylinder 27 is connected to the supply port 31. The supply passage 32 is inserted into a hole formed in the upper platen 15 with a diameter larger than the outer diameter of the supply passage 32. A gap 33 is formed between the hole and the supply passage 32. The gap 33 serves as an air insulating layer to prevent heat from the upper platen 15 from being transferred to the paint 4 flowing through the supply passage 32.

[0048] (Supply Valve 34) The supply passage 32 shown in FIG. 2 is provided with a supply valve 34. The supply valve 34 opens the supply passage 32 when the piston 28 moves in the suction direction (upward) to expand the volume of the metering cylinder 27, as shown in FIGS. 5 and 6 (note that FIG. 6 shows the metering cylinder 27 fully filled with paint 4, with the supply valve 34 closed), and closes the supply passage 32 when the piston 28 moves in the discharge direction (downward) to reduce the volume of the metering cylinder 27, as shown in FIGS. 7 and 8. In this embodiment, the supply valve 34 is a check valve that allows paint 4 to flow from the supply passage 32 to the metering cylinder 27 and prevents paint 4 from flowing from the metering cylinder 27 to the supply passage 32. However, the supply valve 34 may also be a control valve that opens and closes the supply passage 32 as described above. As shown in FIG. 2, a paint tank 35 containing paint 4 is connected upstream of the supply valve 34 via piping 36.

[0049] (On-off valve 7) As shown in Figure 5, a hole 37 is formed through the piston 28 in the axial direction (vertical direction), and an on-off valve 7 that is elongated in the vertical direction is attached to the hole 37 so as to be slidable in the axial direction. The on-off valve 7 has a medium-diameter portion 7a that slides in the hole 37, a tip portion 7b that is integrally formed at the bottom of the medium-diameter portion 7a, and a large-diameter portion 7c that is integrally formed at the top of the medium-diameter portion 7a. The tip portion 7b is received in the passage hole 29 with a predetermined gap in the diametric direction, and has a tip valve portion 7d at its lower end that is formed in a conical shape so as to seat on the valve seat 30. The large-diameter portion 7c has a diameter that slides in a hole 38 formed in the axial direction inside the piston protruding portion 28b, and its upper portion protrudes upward from the piston protruding portion 28b. When the on-off valve 7 rises, the tip valve portion 7d moves away from the valve seat 30 to an open position where the injection port 6 is opened, and when the on-off valve 7 falls, the tip valve portion 7d sits on the valve seat 30 to a closed position where the injection port 6 is closed.

[0050] (Actuator 39) The piston 28 and on-off valve 7 shown in Fig. 5 are each raised and lowered as appropriate by an actuator 39. As shown in Figs. 5 and 6, the actuator 39 lowers the on-off valve 7 to a closed position and moves the piston 28 in the suction direction to raise it, thereby introducing the paint 4 in the paint tank 35 shown in Fig. 2 through the supply port 31 into the metering cylinder 27 and filling the metering cylinder 27 with a predetermined amount of paint 4, and then, as shown in Figs. 7 and 8, raises the on-off valve 7 to an open position and moves the piston 28 in the discharge direction to lower it, thereby injecting the predetermined amount of paint 4 in the metering cylinder 27 through the injection port 6 into the coating agent reservoir 26.

[0051] As shown in FIG. 5 , the actuator 39 includes: a piston actuating flange 40 formed on a portion of the piston 28 protruding from the metering cylinder 27 (piston protruding portion 28 b) in order to move the piston 28 in the axial direction of the metering cylinder 27; a piston actuating cylinder 41 formed to house the piston actuating flange 40 movably along the axial direction of the metering cylinder 27; an on-off valve actuating flange 42 formed on a portion of the large diameter portion 7 c of the on-off valve 7 protruding from the piston 28 (on-off valve protruding portion 7 e) in order to move the on-off valve 7 in the axial direction of the piston 28; and an on-off valve actuating cylinder 43 formed and connected to the piston actuating cylinder 41 in order to house the on-off valve actuating flange 42 movably along the axial direction of the piston 28.

[0052] As shown in FIG. 5 , the piston actuating cylinder 41 and the on-off valve actuating cylinder 43 are each formed inside a cylinder block 45 attached to the upper platen 15 via a support 44. The cylinder block 45 is formed with a first passage 46 for applying fluid pressure to the upper surface of the on-off valve actuating flange 42 and the lower surface of the piston actuating flange 40, and a second passage 47 for applying fluid pressure to the lower surface of the on-off valve actuating flange 42 and the upper surface of the piston actuating flange 40. The first passage 46 includes a passage 46a connecting a hole formed in one side of the cylinder block 45 to a portion of the on-off valve actuating cylinder 43 above the on-off valve actuating flange 42, and a passage 46b connecting the middle of the passage 46a to a portion of the piston actuating cylinder 41 below the piston actuating flange 40. The second passage 47 connects a hole formed in the other side of the cylinder block 45 to a portion of the piston actuating cylinder 41 above the piston actuating flange 40.

[0053] The actuator 39 also has a fluid pressure switching means 48 (see FIG. 2) for switching between a metering mode, in which fluid (air, water, oil, etc.) is supplied to the first passage 46 to apply fluid pressure to the upper surface of the on-off valve operating flange 42 and the lower surface of the piston operating flange 40, causing the on-off valve 7 to close the injection port 6 and the piston 28 to move in the suction direction, as shown in FIGS. 5 and 6, and an injection mode, in which fluid is supplied to the second passage 47 to apply fluid pressure to the lower surface of the on-off valve operating flange 42 and the upper surface of the piston operating flange 40, causing the on-off valve 7 to open the injection port 6 and the piston 28 to move in the discharge direction, as shown in FIGS. 7 and 8.

[0054] 2, the fluid pressure switching means 48 includes a switching valve 49 connected to the first passage 46 and the second passage 47, a tank T (air tank, water tank, oil tank, etc.) that contains a fluid (air, water, oil, etc.) at a predetermined pressure to supply fluid pressure (air pressure, water pressure, oil pressure, etc.), a pump P that pressurizes and supplies the fluid to the tank T, and a control unit C that appropriately switches the switching valve 49. In this embodiment, an example is shown in which air is used as the fluid and an electromagnetic solenoid valve is used as the switching valve 49.

[0055] In the electromagnetic solenoid valve (switching valve 49) shown in Figure 2, when electricity is not supplied from the control unit C to the solenoid 49a of the switching valve 49, the box is pushed to the right by the spring 49b, and the parallel circuit is put into operation. As a result, air in the tank T is supplied to the first passage 46, and air in the second passage 47 is exhausted from the exhaust silencer 50. As a result, as shown in Figures 5 and 6, the on-off valve 7 descends to the closed position, and the piston 28 moves upward (in the suction direction), entering the metering mode.

[0056] On the other hand, when electricity is supplied to the solenoid 49a from the control unit C shown in Figure 2, the solenoid 49a is energized, the box is moved to the left, and the cross circuit is activated. As a result, air in the tank T is supplied to the second passage 47, and air in the first passage 46 is exhausted from the exhaust silencer 50. As a result, as shown in Figures 7 and 8, the on-off valve 7 rises to the open position, and the piston 28 moves downward (in the discharge direction), entering the injection mode.

[0057] (Cooling Mechanism 10) As shown in FIGS. 4( a) and 4(b), a cooling mechanism 10 is provided inside the injector 8 to prevent the paint 4 (thermosetting liquid coating agent) inside the injector 8 from hardening. As shown in FIGS. 4(b) and 5, the cooling mechanism 10 comprises a cooling water passage 10a formed to surround the metering cylinder 27 and the passage hole 29. The cooling water passage 10a is formed in a double spiral shape to surround the metering cylinder 27 and the passage hole 29. The cooling water passage 10a is configured so that cooling water introduced from an inlet 10b formed on the upper left of the injector 8 descends counterclockwise as viewed from above, turns around at the bottom of the injector 8, ascends clockwise, and is discharged from an outlet 10c formed on the upper right of the injector 8. The injector 8 having such a complexly shaped cooling water passage 10a formed therein is manufactured using a metal 3D printer, lost-wax casting, or the like. The cooling water flowing through the cooling water passage 10a prevents the coating material 4 contained in the measuring cylinder 27 and the passage hole 29 from being excessively heated by the heat from the upper mold 2b, which would otherwise cause the curing reaction to proceed.

[0058] (Start of Metering) When a predetermined amount of paint 4 is introduced into the injector 8 of the in-mold coating injection device 1 shown in FIG. 2, first, fluid (air) from the tank (air tank) T is supplied to the first passage 46 as shown in FIG. 5. This causes the on-off valve 7 to descend to its closed position, and the piston 28 to ascend. This creates a negative pressure inside the metering cylinder 27, and the paint 4 from the paint tank 35 shown in FIG. 2 is introduced into the metering cylinder 27 via the supply valve 34 (check valve). If the tip valve portion 7d of the on-off valve 7 were to separate from the valve seat 30, the paint 4 would leak from the injection port 6. To prevent this, a leak prevention spring 48a is provided on the ceiling surface of the cylinder block 45 above the on-off valve actuation flange 42 to urge the on-off valve 7 downward, thereby pressing the tip valve portion 7d against the valve seat 30. Therefore, even if the actuator 39 becomes uncontrollable due to a malfunction or emergency stop, the paint 4 from the injector 8 will not leak into the mold 2. In addition, fluid (air) above the piston actuation flange 40 in the piston actuation cylinder 41 is discharged from the second passage 47 as the piston actuation flange 40 rises, and is exhausted from the exhaust silencer 50.

[0059] (Metering completed) As shown in Figure 6, the piston 28 reaches the top dead center when the piston operating flange 40 of the piston 28 abuts against the ceiling surface of the piston operating cylinder 41, and a predetermined amount of paint 4 is stored in the metering cylinder 27, completing the metering.

[0060] (Injection Start) Next, to inject a predetermined amount of paint 4 into the coating agent reservoir 26 through the injection port 6, fluid (air) from the air tank T shown in FIG. 2 is supplied to the second passage 47 as shown in FIG. 7. This causes the on-off valve 7 to rise, opening the injection port 6, and the piston 28 to descend, reducing the volume of the metering cylinder 27. As a result, the paint 4 in the metering cylinder 27 is injected into the coating agent reservoir 26 through the injection port 6. At this time, the supply valve 34 (check valve) prevents the paint 4 in the metering cylinder 27 from flowing back toward the paint tank 35 shown in FIG. 2. Note that fluid below the piston actuating flange 40 in the piston actuating cylinder 41 is discharged from the first passage 46 as the piston actuating flange 40 descends, and fluid above the on-off valve actuating flange 42 in the on-off valve actuating cylinder 43 is discharged from the first passage 46 as the on-off valve actuating flange 42 ascends.

[0061] (Injection completed) As shown in Figure 8, the underside of the stroke adjustment ring 51 attached to the piston 28 abuts against the top surface of the injection machine 8, causing the piston 28 to reach bottom dead center and completing the injection of the specified amount of paint 4. By appropriately changing the thickness t of the stroke adjustment ring 51, the stroke S (see Figure 6) from top dead center to bottom dead center can be adjusted, and the amount of paint 4 injected can be regulated. Furthermore, by pressing the tip valve portion 7d of the on-off valve 7 against the valve seat 30 with the leak prevention spring 48a, the paint 4 in the injection machine 8 can be prevented from leaking into the coating agent reservoir 26 in the mold 2.

[0062] (Operations and Effects) According to the in-mold coating injection device 1 according to this embodiment and the in-mold coating injection method using the same, the following effects can be achieved.

[0063] As shown in FIG. 2, the in-mold coating injection device 1 according to this embodiment injects a paint 4 (thermosetting liquid coating agent) as a coating agent into a coating gap 13 between the outer surface of a substrate 3 held inside a mold 2 (upper mold 2 b, lower mold 2 a) heated by a heating mechanism 19 and the inner surface of a cavity 14 of the upper mold 2 b, in a predetermined amount corresponding to the volume of the space defined by the coating gap 13.

[0064] As shown in FIG. 5, this in-mold coating injection device 1 is equipped with an injector 8 having an injection port 6 at its tip 8a and a tip valve portion 7d of an on-off valve 7 that opens and closes the injection port 6, and which injects the paint 4 sprayed from the injection port 6 into a coating gap 13 between the outer surface of the molding substrate 3 and the inner surface of the cavity 14 of the upper mold 2b, and an insulating layer 9 that is provided between the tip 8a of the injector 8 and the tip hole portion 11a of the mounting hole 11 of the upper mold 2b and is made of a material (ceramic) with a thermal conductivity lower than that of the material of the tip 8a (steel, cast iron, etc.).

[0065] Therefore, as shown in Figure 2, heat from a heating mechanism 19 provided in the upper mold 2b for hardening the paint 4 (thermosetting liquid coating agent) injected into the coating gap 13 is transmitted to the tip 8a of the injector 8 through the insulating layer 9, suppressing heat transmission from the upper mold 2b to the tip 8a of the injector 8. As a result, as shown in Figures 7 and 8, the heat received by the paint 4 (thermosetting liquid coating agent) from the upper mold 2b in the vicinity of the injection port 6 arranged in the tip 8a and the tip valve portion 7d of the opening / closing valve 7 that opens and closes the injection port 6 can be reduced.

[0066] As a result, in Figures 7 and 8, the hardening reaction of the paint 4 near the injection port 6 of the injection machine 8 and the tip valve portion 7d of the on-off valve 7 that opens and closes the injection port 6, i.e., the hardening reaction of the paint 4 immediately before it is injected into the coating gap 13, is suppressed, and problems caused by the hardening of the paint 4, such as the generation of contamination (impurities, foreign matter), blockage of the injection port 6, sticking between the tip valve portion 7d of the on-off valve 7 and the valve seat 30, and sticking between the tip portion 7b of the on-off valve 7 and the passage hole 29, can be prevented, and a stable injection state can be achieved.

[0067] 3 and 4, the in-mold coating injection device 1 is provided with a cooling mechanism 10 for cooling the paint 4 inside the injector 8 to prevent the paint 4 (thermosetting liquid coating agent) inside the injector 8 from hardening. Therefore, even if part of the heat of the upper mold 2b heated by a heating mechanism 19 provided to harden the paint 4 injected into the coating gap 13 of the upper mold 2b passes through the insulating layer 9 and is transferred to the tip 8a of the injector 8, the paint 4 (thermosetting liquid coating agent) near the inlet 6 of the tip 8a of the injector 8 and the tip valve portion 7d of the on-off valve 7 that opens and closes the inlet 6 can be maintained at a temperature at which an appropriate hardening reaction can be exhibited.

[0068] (Modification) To improve the thermal insulation of the thermal insulating layer 9 (ceramic sprayed layer) provided on the stepped surface 8z of the outer peripheral surface 8x of the tip 8a of the injector 8 shown in FIG. 8 , it is possible to spray ceramic onto the stepped surface 8z of the outer peripheral surface 8x of the tip 8a so that the ceramic sprayed layer 9 is porous. This can reduce the thermal conductivity of the thermal insulating layer 9 (ceramic sprayed layer) to 1 W / m·K or less, significantly reducing the heat input from the upper mold 2b to the tip 8a of the injector 8. However, if the thermal insulating layer 9 (ceramic sprayed layer) is porous, some of the paint 4 (thermosetting liquid coating agent) sprayed from the inlet 6 of the injector 8 into the coating agent reservoir 26 may come into contact with and stick to the end surface of the thermal insulating layer 9 (ceramic sprayed layer), making it difficult to release from the mold. A modification that solves this problem will be described using FIGS. 9 and 10 .

[0069] 9(a) shows a cross-sectional view of the tip 8a of the injector 8 of the in-mold coating injection device 1 according to a modified example of the present invention. The in-mold coating injection device 1 according to the modified example has a basic configuration similar to that of the in-mold coating injection device 1 according to the embodiment described above with reference to FIGS. 2 to 8. Therefore, the same components are denoted by the same reference numerals and their descriptions are omitted, and only differences will be described.

[0070] 9(a), a flange portion 8w is provided on a stepped surface 8z on the outer peripheral surface 8x of the tip portion 8a of the in-mold coating injection device 1 according to the modified example, positioned closer to the tip surface 8y than the thermal insulating layer 9 (ceramic sprayed layer) provided on the stepped surface 8z. The outer diameter A of the edge of the flange portion 8w is smaller than the outer diameter B of the surface of the thermal insulating layer 9. The outer diameter B of the surface of the thermal insulating layer 9 is equal to the hole diameter C of the tip hole portion 11a of the mounting hole 11. Therefore, a gap G is formed between the edge of the flange portion 8w and the tip hole portion 11a of the mounting hole 11 in the upper mold 2b.

[0071] Figures 10(a), 10(b), and 10(c) show the manufacturing process for the flange portion 8w of the tip portion 8a and the thermal insulating layer 9. First, as shown in Figure 10(a), a step surface 8z having a smaller diameter than the outer peripheral surface 8x and a flange portion 8w having a larger diameter than the step surface 8z but smaller than the outer peripheral surface 8x are machined using a lathe or the like on the outer peripheral surface 8x of the tip portion 8a of the injector 8. Next, as shown in Figure 10(b), ceramic (e.g., zirconia) is sprayed onto the step surface 8z so that it has a larger diameter than the outer peripheral surface 8x. Thereafter, as shown in Figure 10(c), the sprayed ceramic is polished (cut) to be flush with the outer peripheral surface 8x, completing the ceramic sprayed layer 9 as a thermal insulating layer.

[0072] As shown in Figure 9(a), the outer diameter B of the ceramic sprayed layer 9 is the same as the diameter C of the tip hole 11a of the mounting hole 11, and the outer diameter A of the edge of the flange portion 8w is slightly smaller than the diameter C of the tip hole 11a of the mounting hole 11. In this embodiment, the outer diameter B of the ceramic sprayed layer 9 is 10.000 mm, the diameter C of the tip hole 11a of the mounting hole 11 is 10.000 mm, and the outer diameter A of the edge of the flange portion 8w is 9.994 mm, leaving a small gap G of 0.006 mm (6 µm) between the edge of the flange portion 8w and the inner surface of the tip hole 11a of the mounting hole 11. Note that the gap G is not limited to 6 µm and may be in the range of 1 to 9 µm.

[0073] (Actions and Effects of Modified Example) When the injection machine 8 according to the modified example shown in Figure 9(a) is used to inject the paint 4 (thermosetting liquid coating agent) into the coating gap 13 between the outer surface of the molding substrate 3 shown in Figure 2 and the inner surface of the cavity 14 of the upper mold 2b, the paint 4 (thermosetting liquid coating agent) is sprayed from the injection port 6 of the tip 8a of the injection machine 8 shown in Figure 9(a) into the coating agent reservoir 26, and part of the sprayed paint 4 (thermosetting liquid coating agent) enters the gap G between the tip hole 11a of the mounting hole 11 of the upper mold 2b and the edge of the flange portion 8w of the injection machine 8, and as shown in Figure 9(b) and its enlarged partial view, Figure 9(c), the paint 4 (thermosetting liquid coating agent) that has entered the gap G is hardened by the heat from the upper mold 2b. The hardened paint 4 (thermosetting liquid coating agent) functions as a plug Z that closes the gap G, thereby preventing the paint 4 (thermosetting liquid coating agent) sprayed from the injection port 6 from penetrating through the gap G into the heat insulating layer 9 (ceramic sprayed layer).

[0074] Therefore, even if ceramic is sprayed onto the stepped surface 8z of the tip 8a of the injector 8 so as to make the ceramic sprayed layer 9 porous in order to improve the thermal insulation of the thermal insulation layer 9 (ceramic sprayed layer), the paint 4 (thermosetting liquid coating agent) sprayed from the inlet 6 of the injector 8 into the coating agent reservoir 26 can be prevented from coming into contact with and biting into the end face of the thermal insulation layer 9 (ceramic sprayed layer) through the gap G shown in Figure 9(a), making demolding easier. Also, deterioration of the ceramic sprayed layer 9 due to the paint 4 penetrating into the interior of the thermal insulation layer 9 (ceramic sprayed layer) can be prevented. In addition, when the tip 8a of the injection machine 8 is inserted into the tip hole portion 11a of the mounting hole 11 provided in the upper mold 2b, the flange portion 8w functions as a cover (protective member) that protects the corners of the lower end of the insulating layer 9 (ceramic sprayed layer), preventing the corners of the lower end of the insulating layer 9 (ceramic sprayed layer) from hitting the edge of the tip hole portion 11a and being damaged.

[0075] The above describes a preferred embodiment of the present invention with reference to the accompanying drawings. However, it goes without saying that the present invention is not limited to the above-described embodiment, and various modified or altered examples within the scope of the claims also fall within the technical scope of the present invention.

[0076] The present invention can be used in an in-mold coating injection device that injects a thermosetting liquid coating agent into a coating gap between a substrate held inside a heated mold and the inner surface of the mold, and an in-mold coating injection method using the same.

[0077] 1 In-mold coating injection device 2 Mold 2a Lower mold 2b Upper mold 3 Molding substrate 4 Thermosetting liquid coating agent (paint) 6 Inlet 7 On-off valve 7d Tip valve portion 8 Injector 8a Tip portion 8b Medium diameter portion 8c Large diameter portion 8x Outer circumferential surface 8y Tip surface 8z Step surface 8w Flange portion 9 Heat insulating layer (ceramic sprayed layer) 10 Cooling mechanism 10a Cooling water passage 11 Mounting hole 11a Tip hole portion 12 Core 13 Coating gap 14 Cavity 26 Coating agent reservoir G Gap A Outer diameter of edge portion of flange portion 8w B Outer diameter of surface of heat insulating layer 9 Z Plug where paint 4 that has penetrated into gap G has hardened

Claims

1. An in-mold coating injection device that injects a thermosetting liquid coating agent between the outer surface of a substrate held inside a heated mold and the inner surface of the mold, comprising: an injector having an injection port at its tip and an on-off valve for opening and closing the injection port, and for injecting the thermosetting liquid coating agent sprayed from the injection port between the outer surface of the substrate and the inner surface of the mold; and an insulating layer disposed between the tip of the injector and the mold, the insulating layer being made of a material with a thermal conductivity lower than that of the material of the tip.

2. The in-mold coating injection device according to claim 1, characterized in that the injection machine is provided with a cooling mechanism to prevent the thermosetting liquid coating agent inside the injection machine from hardening.

3. An in-mold coating injection device as described in claim 2, characterized in that the tip of the injection machine has an outer peripheral surface that is inserted into a mounting hole formed in the mold and a tip surface on which the injection port is provided, and the insulating layer is provided on the outer peripheral surface of the tip so as to contact the inner peripheral surface of the mounting hole.

4. An in-mold coating injection device according to any one of claims 1 to 3, characterized in that the thermal conductivity of the heat insulating layer is lower than the thermal conductivity of the mold.

5. An in-mold coating injection device according to any one of claims 1 to 3, characterized in that the heat insulating layer is a thermal sprayed layer.

6. The in-mold coating injection device according to claim 5, wherein the thermal sprayed layer is a ceramic thermal sprayed layer formed by thermal spraying a ceramic.

7. An in-mold coating injection device as described in claim 3, characterized in that a flange portion is provided on the outer peripheral surface of the tip of the injection machine, positioned closer to the tip surface than the insulating layer provided on the outer peripheral surface, the outer diameter of the edge of the flange portion is smaller than the outer diameter of the surface of the insulating layer, and a gap is formed between the edge of the flange portion and the mounting hole of the mold.

8. The in-mold coating injection device according to claim 7, wherein the heat insulating layer is porous.

9. An in-mold coating injection method for injecting the thermosetting liquid coating agent between the outer surface of the molding substrate and the inner surface of the mold using an in-mold coating injection device as defined in any one of claims 1 to 3, characterized in that heat from the mold is transmitted to the tip of the injection machine through the heat insulating layer, thereby suppressing heat transmission from the mold to the tip of the injection machine, and suppressing the curing reaction of the thermosetting liquid coating agent near the injection port arranged at the tip of the injection machine and the on-off valve that opens and closes the injection port.

10. An in-mold coating injection method for injecting the thermosetting liquid coating agent between the outer surface of the molding substrate and the inner surface of the mold using the in-mold coating injection device described in claim 7 or 8, characterized in that a portion of the thermosetting liquid coating agent sprayed from the injection port of the injection machine enters the gap between the mounting hole of the mold and the edge of the flange portion of the injection machine, and the thermosetting liquid coating agent that has entered the gap hardens due to the heat from the mold, thereby preventing the thermosetting liquid coating agent sprayed from the injection port from penetrating through the gap into the heat insulating layer.

Images