JP2001096572A - Method for production of insert molded article and insert molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly apply a paint to a mold cavity and to reduce production cost. SOLUTION: A soln. of a paint M is poured in the cavity 17 of an opened mold 7 and, after the core 10 of a steering wheel 1 is set in the cavity 17, the mold 7 is closed and a vacuum pump 34 is driven to evacuate the cavity 17. Whereupon, the solvent of the paint M is boiled and the paint M is uniformly applied to the wall surface of the cavity 17 efficiently by the volumetric increase and foam breaking of the paint M at the time of boiling. The surface of the core 10 is washed by the boiling and evaporation of the solvent of the paint M and the urethane paint M functioning as an adhesive is adhered to the surface of the core 10. Therefore, a process for washing the core 10 and a process for coating the core 10 with the adhesive are simplified or omitted to produce the steering wheel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an insert-molded article in which a paint is previously applied to a cavity in a mold (mold coating) in order to simultaneously perform molding and coating of a molded article having an insert member, and insert molding. The present invention relates to a method of manufacturing a steering wheel, and particularly to a steering wheel.

[0002]

2. Description of the Related Art Conventionally, a steering wheel for an automobile has a so-called insert formed by setting a core metal as an insert member in a mold cavity (a cavity for forming a molded product), injecting a resin material, curing the resin material, and molding. It is molded by molding. The urethane resin used as a filling material for the steering wheel has a disadvantage that it is inferior in light resistance and yellows, and therefore it is necessary to form a coating film on the surface of the resin part to have light resistance.

As a method of forming the coating film, a method of applying a coating material in advance to a cavity in a mold and simultaneously forming and coating a product has been applied. Specifically, the mold is opened, and a coating solution is applied to the cavity by a spray gun (mold coating). Then, after setting the core metal of the steering wheel in the cavity, the mold is closed, and a urethane material is mixed and injected into the cavity to be cured. As a result, a light-resistant coating film is formed on the surface of the resin portion of the steering wheel. In addition, a molding method in which a predetermined material is mixed and injected into a mold cavity and cured by reaction is called reaction injection molding (RIM). The paint used here is composed of, for example, methyl ethyl ketone (MEK) and isopropyl alcohol (IPA) as solvents and a urethane resin having excellent light resistance.

[0004]

However, when a coating solution is applied (mold coated) with a spray gun,
There is a possibility that the coating material cannot be applied uniformly and light resistance cannot be sufficiently secured. In particular, in the part of the parting line in the ring portion of the steering wheel, the coating cannot be performed sufficiently, and the thickness of the coating film becomes thin. Therefore, in the part of the parting line, light resistance may be deteriorated due to abrasion of the coating film.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide insert molding capable of uniformly applying a coating material to a mold cavity and reducing manufacturing costs. An object of the present invention is to provide a method for manufacturing a product, a method for manufacturing a steering wheel, an insert molded product, and a steering wheel.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, when a filling material is injected into a mold cavity and cured to mold an insert member, molding and painting are performed. In order to perform simultaneously, in the method of manufacturing an insert molded product in which a coating solution is applied to the surface of the mold cavity in advance, the step of setting the insert member, and coating the mold cavity with the mold closed The gist of the invention is to include a coating layer forming step of forming a layer and a step of filling a filling material into a mold cavity.

According to a second aspect of the present invention, in the first aspect of the present invention, in the coating film layer forming step, the coating solution is boiled, and the coating film is formed on the mold cavity by an increase in volume and boiling during boiling. The gist is to form a layer.

According to a third aspect of the present invention, in the first or second aspect of the invention, the filling material is a urethane material, and after forming a coating film layer in the mold cavity,
The gist is that a urethane material is mixed and injected into a mold cavity, cured by reaction, and the insert member is molded with a resin.

According to the fourth aspect of the invention, the first to third aspects are provided.
In the invention according to any one of the above, the gist is that the inside of the mold cavity is in a reduced pressure state. According to the fifth aspect of the present invention, when the filling material is injected into the mold cavity and cured to mold and mold the core metal of the steering wheel, a coating solution is previously applied to the mold cavity in order to simultaneously perform molding and painting. In the method of manufacturing a steering wheel to be applied, a coating solution is boiled in a mold cavity in which a core metal of the steering wheel is set, and a coating layer is formed in the mold cavity by increasing the volume at the time of boiling and breaking bubbles. The gist is that they did.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, the filling material is a urethane material, and after forming a coating layer in the mold cavity, the urethane material is filled with the mold cavity. Mix and inject and react and cure,
The gist is that the core metal of the steering wheel is formed by molding resin.

According to a seventh aspect of the present invention, in the fifth or sixth aspect, the gist is that the inside of the mold cavity is in a reduced pressure state. Claim 8
According to the invention described in (1), in an insert molded product in which a filler material is injected into a mold cavity in which an insert member is set, and the insert member is molded, a coating material having a substantially uniform thickness is formed on the surface of the filler material. The gist of the invention is to provide a film, and an intermediate layer formed of the same material as the coating film, between the insert member and the filling material.

According to a ninth aspect of the present invention, in the eighth aspect, the filling material is a urethane material which is reactively hardened in a mold cavity.

According to the tenth aspect of the present invention, in a steering wheel in which a filling material is injected into a mold cavity in which a core of a steering wheel is set and the core is molded, the surface of the filling material is substantially uniform. The gist of the present invention is to provide a coating film formed with an appropriate thickness and an intermediate layer formed of the same material as the coating film between the core metal of the steering wheel and the filling material.

According to the eleventh aspect of the present invention, in the tenth aspect,
The gist of the present invention is that the filling material is a urethane material which reacts and hardens in a mold cavity.

(Operation) According to the first aspect of the present invention,
The insert member is set in the mold cavity and clamped. Thereafter, a coating layer is formed in the mold cavity in the mold cavity by a coating layer forming step. When the filling material is injected into the mold cavity in which the coating layer is formed and cured, and the insert member is molded, a coating film is formed on the surface of the molded portion simultaneously with the molding. As described above, since the coating layer is formed in the mold cavity in the closed mold, the coating efficiency of the paint is improved.

According to the second aspect of the present invention, in the coating film layer forming step, the coating solution is boiled in the mold cavity,
The paint is applied to the wall surface of the mold cavity due to the increase in volume at the time of boiling and the breakage of bubbles. As a result, a coating layer is formed in the mold cavity with a uniform thickness. Further, the solvent contained in the coating solution evaporates, and the vaporized solvent cleans the surface of the insert member set in the mold cavity and applies the coating to the surface. Thereby, the adhesiveness between the insert member and the filling material is improved. As a result, the step of applying the adhesive after cleaning the insert member can be simplified or omitted to perform insert molding.

According to the third and sixth aspects of the present invention, the urethane material is mixed and injected into the mold cavity and cured by reaction, whereby molding with a urethane resin is performed. In this case, compared with the injection molding of a general resin, the resin is molded in the cavity under the condition of lower temperature and lower pressure. Therefore, the coating layer formed on the wall surface of the cavity is prevented from being broken by the pressure and temperature during molding.

According to the fourth and seventh aspects of the present invention, the coating solution is boiled in the mold cavity by depressurizing the inside of the mold cavity, and the mold is increased due to an increase in volume at the time of boiling and breakage of bubbles. A coating layer is formed in the cavity.

According to the fifth aspect of the present invention, the coating solution is boiled in the mold cavity in which the core metal of the steering wheel is set, and a coating layer is formed in the mold cavity due to an increase in the volume at the time of boiling and breakage of bubbles. It is formed with a uniform thickness. In particular, in the spray gun, the coating on the parting line in the ring portion having a substantially circular cross section becomes insufficient, but the coating material is also uniformly applied on the parting line. On the other hand, the solvent contained in the coating solution is vaporized, and the vaporized solvent cleans the surface of the core metal set in the mold cavity and applies the coating to the surface. When the filling material is injected into the mold cavity having the coating film layer formed thereon and cured to mold the core metal, a coating film having a substantially uniform thickness is formed on the surface of the molded portion simultaneously with the molding. In addition, the surface of the metal core is cleaned in the cavity to remove impurities on the surface, thereby improving the adhesion between the metal core and the filling material. As a result, it is possible to simplify or omit the step of applying the adhesive after cleaning the cored bar, and perform resin molding of the steering wheel.

According to the eighth aspect of the present invention, since a coating film having a substantially uniform thickness is formed on the surface of the filling material, the light resistance of the surface of the molded product is improved. An intermediate layer of the same material as the coating is formed between the insert member and the filler material. Such an insert molded product can be manufactured by the manufacturing method according to the first aspect. That is, the manufacturing process is simplified or omitted in the steps of cleaning the insert member and applying the adhesive, which is advantageous in cost.

According to the ninth and eleventh aspects of the present invention, a coating film having a substantially uniform thickness is formed on the surface of the urethane resin formed by reaction curing. Accordingly, since a coating film having a substantially uniform thickness is formed on the surface of the urethane resin which is inferior in light resistance and yellowing, the light resistance of the molded product (steering wheel) is improved.

According to the tenth aspect of the present invention, since a coating film having a substantially uniform thickness is formed on the surface of the filling material, the light resistance of the surface of the steering wheel is improved. An intermediate layer of the same material as the coating is formed between the cored bar and the filling material. Such a steering wheel can be manufactured by the manufacturing method according to the fourth aspect. That is, the manufacturing process is simplified or omitted in the steps of cleaning the core metal and applying the adhesive, which is advantageous in terms of cost.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

1 to 3 are partial cross-sectional views of an injection molding machine according to the present embodiment, and FIG. 4 is a perspective view of a vehicle steering wheel 1 formed by the injection molding machine. As shown in FIG. 4, the steering wheel 1 has a ring portion 2, spoke portions 3, 4, 5, and a boss portion 6. The upper mold 9) includes the core 1 of the ring 2 and the spokes 3, 4, and 5.
0 is coated with a urethane resin. In addition,
In the present embodiment, foam molding of urethane resin is performed with the steering wheel 1 shown in FIG. 4 turned upside down.

As shown in FIGS. 1 to 3, the mold 7 is
It is arranged in a box 13 consisting of a lid 1 and a lid 12. Specifically, the lower die 8 of the die 7 is fixed to the frame 11, and the upper die 9 of the die 7 is fixed to the lid 12. In addition, a seal member 14 is provided at a joint of the lid 12 and the frame 11. Then, the frame 11 and the lower mold 8 are moved upward from the state where the mold 7 is opened as shown in FIG. 1, and the mold 7 is moved in a state where the core metal 10 is set as shown in FIG. Closed and clamped. At this time, a box 13 is formed by the frame 11 and the lid 12, and the inside of the box 13 is sealed by the seal member 14. Further, the core 10 of the present embodiment is manufactured by die-casting of aluminum die-cast, magnesium die-cast, or an alloy thereof, and the cross-sectional shape of the ring portion 10a of the core 10 is U-shaped as shown in FIG. It has become.

Concave portions 15 and 16 are formed in the lower die 8 and the upper die 9, and the concave portions 15 and 16 become cavities 17 for forming a molded product shape. In order to fix the metal core 10 of the steering wheel 1 at the time of molding, a fixing member 18 is protruded from the center of the lower die 8 and a fixing member 19 is protruded from the center of the upper die 9. . Furthermore, upper mold 9
The recess 16 has a discharge hole 20 (for example, a sectional area = 4 mm).
² ) is formed, and the cavity 17 is formed by the discharge hole 20.
Is communicated with the hollow portion 21 in the box 13.

One side wall of the frame 11 (the right side wall in the figure)
An injection nozzle 22 is provided on the side, and a urethane material as a filling material mixed by a urethane injection device (not shown) is injected from the injection nozzle 22 into the cavity 17 through the gate 23. This urethane material is liquid and contains a polyol component, an isocyanate component and a foaming component. A discharge pipe 31 is provided on the other side wall (the left side wall in the figure) of the frame 11, and the discharge pipe 31 is connected to a pipe 32.
And a valve 33 connected to a vacuum pump 34. When the vacuum pump 34 is driven, the air in the box 13 is discharged from the discharge pipe 31, and the pressure in the box 13 is reduced.

Next, a method of molding the urethane resin of the steering wheel 1 according to the present embodiment will be described with reference to FIGS. First, as shown in FIG. 1, the mold 7 is opened and the cavity 17 (the concave portion 15 of the lower die 8 and the concave portion 1 of the upper die 9) is opened.
6) Apply a mold release agent to the wall surface. The release agent is made of wax, silicone oil, or the like, and is applied for the purpose of preventing the molded product from sticking to the mold 7 and facilitating removal of the molded product.

Next, while the mold 7 is kept horizontal, the liquid paint M (in this embodiment, 150 g) is poured into the recess 15 of the lower mold 8.
Pour into. The solution of the coating material M in the present embodiment contains methyl ethyl ketone (MEK) and isopropyl alcohol (IPA) as solvents and a urethane resin as a solid content. In addition, when the ratio of each component in the coating material M is represented by% by weight, MEK = about 85%, IPA = about 10%, and urethane resin = 2.5%. Then, as shown in FIG. 2, the core metal 10 is set in the mold 7, and the mold 7 is closed and clamped. At this time, the frame 11 and the lid 12 are joined via the seal member 14, and the inside of the box 13 is closed.

Thereafter, the vacuum pump 34 is driven to drive the discharge pipe 3
The pressure in the box 13 is reduced by discharging the air in the box 13 from 1. At this time, the air in the cavity 17 is sucked into the hollow portion 21 in the box 13 through the discharge hole 20, and the pressure in the cavity 17 is also reduced. When the pressure in the cavity 17 is reduced, the solvent of the paint M (MEK, IP
The boiling point of A) decreases. As a result, the paint M boils and breaks bubbles with an increase in volume. Specifically, the temperature of the mold 7 is maintained at 55 ° C.
When the pressure is reduced below torr, the solvent boils. Due to the increase in volume and the breakage of bubbles at the time of boiling, the paint M
Is uniformly applied to the wall surface.

On the other hand, the surface of the metal core 10 is cleaned by a solvent which is boiled and vaporized by the decompression in the cavity 17, and the paint M which plays the role of an adhesive on the surface of the metal core 10 by breaking bubbles at the time of boiling. Is attached. Note that the vaporized solvent is exhausted from the vacuum pump 34 through the discharge hole 20 via the hollow portion 21 in the box 13 and the discharge pipe 31. The mold 7 is held horizontally while the pressure of the cavity 17 is reduced after the paint M is poured into the cavity 17. The reason for this is to prevent the coating material M from being biased at a predetermined portion in the cavity 17 and to uniformly apply the coating material M to the side wall of the cavity 17.

After the vacuum pump 34 is stopped, the urethane material mixed in the injection device main body (not shown) is injected into the cavity 17 from the injection nozzle 22 through the gate 23, and the same material as shown in FIG. The reaction hardens in the cavity 17. Specifically, the foaming component reacts with the isocyanate component to generate CO2, and the polyol component reacts with the isocyanate component, whereby the urethane resin is foamed and molded.

Thus, the steering wheel 1
The molding and coating of the urethane resin of the ring portion 2 and the spoke portions 3, 4, and 5 are simultaneously performed. That is, a coating film of the light-resistant urethane resin U1 is formed on the surface of the urethane resin U2 with a substantially uniform thickness (for example, 10 μm). In addition, the surface of the core metal 10 is cleaned in the cavity 17 to remove impurities adhering to the surface. Further, a urethane resin-based coating material M having excellent adhesiveness is applied to the cleaned surface. Thereby, the adhesion between the core metal 10 and the urethane resin U2 that has been cured by reaction is improved.
In addition, the urethane resin U1 formed between the core metal 10 and the urethane resin U2 serves as an adhesive layer (intermediate layer). That is,
When the molding method of the present embodiment is adopted, a coating film and an adhesive layer are formed by the urethane resin U1 constituting the coating material M.

In addition, foam molding using a liquid urethane material is more efficient than injection molding of a general thermoplastic resin.
The resin molding is performed under the condition that the temperature inside the cavity 17 is low and the pressure is low. Therefore, the coating layer formed on the wall surface of the cavity 17 is prevented from being broken by the pressure and temperature during molding.

Thereafter, the mold 7 is opened, and as shown in FIG. 4, the steering wheel 1 in which the ring portion 2 and the spoke portions 3, 4, 5 are covered with urethane resin U1, U2 is taken out, and the molding process is performed. finish. In this embodiment, since the resin molding is performed with the steering wheel 1 turned upside down, a thicker urethane resin U1 coating film is formed on the steering wheel 1 where light resistance is required.

Table 1 shows the results obtained by confirming the state of formation of the coating film (urethane resin U1) on the resin surface of the steering wheel 1 using a color difference meter. Table 1 shows the measurement results of a developed product molded by the above method and a conventional product molded by applying (mold coating) the paint M with a spray gun. The actual steering wheel 1
In this example, the same color is used for the urethane resin U1 and the urethane resin U2. However, in order to confirm the formation state of the urethane resin U1 by using a color difference meter, the urethane resin U1 is excluding the coloring component of the foamed urethane resin U2. The steering wheel is molded. Table 1 shows the measurement results of each part in the ring portion of each of the confirmation steering wheels. The color difference ΔE from the other parts is set using the uppermost color where the coating film is formed thick as a reference color. Is shown. In other words, if the color difference ΔE is “0”, it means that the same film thickness as the uppermost portion is formed, and the larger the color difference ΔE, the larger the film thickness difference from the uppermost portion. Further, the measurement sites here include an intermediate position (upper intermediate portion) between the uppermost portion and the parting line portion (PL portion), a PL portion, an intermediate position between the PL portion and the lowermost portion (lower intermediate portion), At the bottom.

As shown in Table 1, in the conventional product, the color difference ΔE is large in each part, especially in the PL part.
The reason for this is that when the coating solution is applied with a spray gun, the thickness of the formed coating film becomes non-uniform at each part, and in particular, the thickness of the PL portion having a surface orthogonal to the parting surface is the highest. This is because it is thinner in comparison. On the other hand, in the developed product, the color difference ΔE is small, and it can be seen that the coating film is formed with a substantially uniform thickness. Also, the color difference Δ
It can be seen that E is small and a coating film having a thickness substantially equal to that of the uppermost portion is formed.

[0038]

[Table 1] Next, the coating film forming method of the present invention, that is, the paint (150
g) is injected into the cavity 17, and the pressure is 300 torr.
(40 kPa) or less when a coating film is formed on the cavity 17 by applying a pressure reduction below 40 kPa.
Table 2 shows the results of measuring the peel strength of the resin portion from the core 10 when a coating film was formed on the core metal 10. Further, Table 2 shows the measurement results of the peel strength when the processing method of the core metal 10 is changed. Specifically, the treatment of the core 10 includes a treatment of cleaning the surface of the core 10 and a treatment of immersing the core 10 in a solution of an adhesive. In the case of (1), the peeling strength is shown when only the cleaning treatment is performed, and when both the cleaning treatment and the adhesive immersion treatment are performed.

As shown in Table 2, the peel strength in the coating film forming method of the present invention is 10.8 N · m when the core metal 10 is not treated, and 12 when the cleaning is performed only. When the cleaning process and the adhesive immersion process were performed, the value was 14.7 N · m.
On the other hand, the peel strength in the method of forming a coating film by spray gun application is 1.8 N · m in the case of no treatment, and 5.6 N · m in the case where only the cleaning treatment is performed. In the case of performing the immersion treatment, 17.2
N · m. That is, in the case of spray gun application, if the surface treatment of the core metal 10 is not performed, the peel strength becomes insufficient, so that the surface treatment of the core metal 10 is required. However, when the coating film forming method of the present invention is employed, even if the surface treatment is not performed, the peel strength is 10 N ·
m or more, and a sufficiently satisfactory adhesive strength can be secured. Therefore, if the forming method of the present embodiment is adopted, it is possible to simplify or omit the cleaning process of the core bar 10 and the immersion process of the adhesive, which are conventionally required.

[0040]

[Table 2] When the paint M was applied by a spray gun as in the prior art, the efficiency of application into the cavity 17 was about 20%. On the other hand, when the paint M is applied in the closed cavity 17 as in the present embodiment, the application efficiency in the cavity 17 can be increased to about 50% to 70%.

As described above, the present embodiment has the following advantages. (1) The solvent in the paint M boils by reducing the pressure in the cavity 17 into which the paint M has been poured, and the paint M is uniformly applied to the side wall of the cavity 17 without unevenness due to an increase in volume at the time of boiling and breakage of bubbles. it can. Specifically, when applied with a spray gun, the coating material M cannot be applied uniformly, and in particular, the application to the part of the parting line in the ring portion 2 having a substantially circular cross section becomes insufficient. I will. If the parting line is repeatedly coated, the occurrence of burrs may be worsened or the concave portion 1
There is a possibility that the coating layer formed on the bottoms of the layers 5 and 16 becomes too thick and the drying property is deteriorated, and that the coating film in that portion is easily peeled off. However, if the molding method of the present embodiment is adopted, the coating material M can be evenly applied to the parting line portion of the ring portion 2.

(2) The core 10 in the cavity 17
Is cleaned and impurities adhering to the surface are removed, so that the adhesion between the core metal 10 and the urethane resin is improved. Further, in the present embodiment, a urethane resin-based coating material M having excellent adhesiveness is applied to the surface of the cleaned cored bar 10. As a result, the core metal 10 and the urethane resin can be firmly fixed. Therefore, the step of cleaning the core metal 10 and the step of applying an adhesive to the core metal 10 which are required in the related art can be omitted, and the manufacturing cost can be reduced.

(3) Since the coating material M is applied in the closed mold 7, the coating efficiency can be increased as compared with the case where the coating material M is applied (mold coated) by a spray gun. Material cost of M can be reduced. Further, the coating material M is not applied to the outside of the cavity 17, so that generation of burrs at the time of molding can be prevented. As a result, manufacturing costs can be kept low. Further, the paint M is prevented from scattering to the outside, the work place can be kept clean, and the deterioration of the surrounding environment can be prevented.

(4) A coating film of the urethane resin U1 having excellent light resistance is formed on the surface of the resin portion of the steering wheel 1 with a substantially uniform thickness. As a result, light resistance can be obtained uniformly at any place, and discoloration of the urethane resin U2 can be prevented.
In addition, there is no unevenness in color on the product surface, and it is possible to prevent poor appearance.

(5) When the solution of the coating material M is poured into the cavity 17, a coating film having a desired thickness can be formed only by adjusting the injection amount of the coating material M. In other words, a coating film having an appropriate thickness can be formed on a part that is easily worn, for example, on a parting line.

(6) In foam molding using a urethane material, compared with injection molding of a thermoplastic resin, cavity 17
Since the resin molding is performed under the conditions of low temperature and low pressure inside, the coating layer applied to the wall surface of the cavity 17 can be prevented from being broken. That is, the product yield can be improved.

(7) Since the pressure in the cavity 17 is reduced while the mold 7 is kept horizontal, the bias of the paint M in the cavity 17 is prevented, and the paint M is uniformly applied to the cavity 17. It becomes possible.

(Second Embodiment) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. This embodiment differs from the first embodiment in that a paint injection device is provided. Since the shape of the cavity 17 and the configuration of the vacuum box 13 and the like are the same as those in the first embodiment, the drawings and detailed description thereof will be omitted.

FIG. 5 is a schematic diagram showing a schematic configuration of the injection molding machine in the present embodiment. In FIG. 5, a cavity 17 and a gate 23 formed in the mold 7 are indicated by dotted lines. As shown in FIG. 5, the coating material M from the coating material injection device 40 is injected into the cavity 17 of the mold 7 through the gate 23. Further, the urethane material mixed by the urethane injection device 41 is supplied to the cavity 17 of the mold 7 through the gate 23.
Is injected into. That is, in the present embodiment, the coating solution and the urethane material are injected into the cavity 17 from the common gate 23. When the injection molding machine is configured as described above, the coating solution can be injected into the cavity 17 with the mold 7 closed.

More specifically, after a mold release agent is applied to the cavity 17 of the mold 7, the core metal 10 is set in the mold 7 and the mold is clamped. Then, the vacuum pump 34 is driven to reduce the pressure in the mold cavity 17. When the pressure in the cavity 17 decreases to a predetermined pressure or less, the paint M is injected into the cavity 17 from the paint injection device 40. At this time, paint M
Of the solvent boiled, and the foamed paint M flows toward the discharge hole 20 in the cavity 17 while breaking the foam. Thereby, the paint M is applied to the wall surface of the cavity 17.
Then, the solvent of the paint M is vaporized, and the urethane resin of the paint M is formed on the wall surface of the cavity 17.

After the coating layer is formed on the wall surface of the cavity 17 as described above, the urethane material mixed by the urethane injection device 41 is injected into the cavity 17 through the gate 23. Then, the same material reacts and hardens in the cavity 17, whereby urethane resin molding of the steering wheel 1 is performed.

As described above, the present embodiment has the following effects in addition to the effects (1) to (7) of the first embodiment. (1) Since the paint M can be injected while reducing the pressure in the cavity 17, resin molding of the steering wheel 1 can be performed in a short time. Further, since the paint M is injected into the cavity 17 in the closed mold 7, it is possible to prevent the solvent of the paint M from leaking out of the injection molding machine, thereby improving the working environment.

(2) By precisely controlling the amount of the paint solution injected by the paint injection device 40, a coating film having a desired thickness can be formed on the surface of the molded article. As a result, it is possible to reduce product variations based on the amount of the paint M to be injected.

The above embodiment may be implemented in the following manner. In the second embodiment, the paint M is injected into the cavity 17 in a reduced pressure state. However, the paint M is injected from the paint injection device 40 into the cavity 17 in a normal pressure state before the pressure is reduced. Is also good.

In the second embodiment, the coating solution is injected from the gate 23 for injecting the urethane material. However, the coating solution may be injected into the cavity 17 from a place other than the gate 23. . Further, a configuration in which the coating solution is injected into the cavity 17 from a plurality of locations may be adopted. Also in this case, the paint M can be efficiently applied to the wall surface of the cavity 17.

In the above-described embodiment, foam molding is performed by CO2 due to the reaction between the isocyanate component and the foaming component. However, foam molding using a foaming agent that is vaporized by the heat of reaction between the polyol component and the isocyanate component may be used. Good. In addition, the present invention is not limited to reaction injection molding such as foam molding using a urethane material, and other resin materials,
Alternatively, it may be injection molded using a rubber material or the like.
In short, what is necessary is just to shape | mold the product which has an insert member by what is called insert molding. However,
As described above, application to reaction injection molding in which a urethane material reacts and cures in the cavity 17 is practically preferable because molding can be performed under low pressure and low temperature conditions. Further, the molded article may be applied to home electric appliances and the like in addition to automobile parts.

The insert member does not need to be made of metal, but may be made of, for example, resin or glass. -The components of the coating material M may be changed as appropriate. Specifically, another thermosetting resin may be used instead of the urethane resin. Further, as a solvent of the coating material M, methyl ethyl ketone (MEK) and isopropyl alcohol (IPA)
Other solvents may be used. Alternatively, toluene or the like may be added to the solvent for MEK or IPA. In practice,
What is necessary is just to use a solvent having a boiling point of about 160 ° C. or less.

In the above embodiment, the inside of the cavity 17 is depressurized to 300 torr or less by driving the vacuum pump 34, but the invention is not limited to this. For example, if the temperature of the mold 7 is normal temperature (about 20 ° C.), the pressure inside the cavity 17 is reduced to about 70 torr. In addition, paint M
Since the boiling point changes when the solvent is changed, the pressure at the time of reducing the pressure in the cavity 17 is also changed in this case. That is, the pressure at the time of decompression in the cavity 17 is appropriately changed according to the temperature of the mold 7 and the type of the solvent used.

In the above embodiment, the step of cleaning the cored bar 10 and the step of applying the adhesive to the cored bar 10 are omitted, but these steps may be performed. In this case, the adhesive strength can be improved. Alternatively, the amount of the adhesive applied to the insert member can be reduced according to the adhesive strength of the coating layer, so that the manufacturing cost can be reduced.

[0060]

As described in detail above, according to the present invention,
The paint can be uniformly applied to the mold cavity, and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a view for explaining a method of forming a steering wheel according to a first embodiment.

FIG. 2 is a view for explaining a method of forming a steering wheel according to the first embodiment.

FIG. 3 is a view for explaining a method of forming the steering wheel according to the first embodiment.

FIG. 4 is a perspective view of the steering wheel of the first embodiment.

FIG. 5 is a schematic diagram illustrating a schematic configuration of an injection molding machine according to a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Steering wheel for vehicles, 7 ... Die, 10 ... Core, 17 ... Cavity, M ... Paint, U1 ... Urethane resin as an intermediate layer and a coating film, U2 ... Urethane resin.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D030 DA35 DA44 DB81 DB82 4F206 AA42L AD18 AD34 AH19 JA01 JB12 JF01 JF05 JF06 JL02 JM02 JN25 JN26 JQ81

Claims (11)

[Claims] 1. An insert in which a coating solution is previously applied to the surface of a mold cavity in order to simultaneously perform molding and painting when a filling material is injected into a mold cavity and cured to mold the insert member. In the method for manufacturing a molded article, a step of setting the insert member, a step of forming a coating layer in a mold cavity with the mold closed, and filling a filling material into the mold cavity. And a process for producing an insert molded product. 2. The method for producing an insert molded product according to claim 1, wherein the coating film layer forming step includes boiling the coating solution, increasing the volume at the time of boiling and breaking the foam to form the coating film layer in the mold cavity. A method for producing an insert molded article, characterized by being formed. 3. The method of manufacturing an insert molded product according to claim 1, wherein the filling material is a urethane material, and after forming a coating layer in the mold cavity, the urethane material is molded into the mold cavity. Characterized by mixing and injecting the mixture into a mixture and reacting and curing the mixture to mold the insert member into a mold resin. 4. The method for manufacturing an insert molded product according to claim 1, wherein the inside of the mold cavity is in a depressurized state. 5. When a filling material is injected into a mold cavity and cured to mold the core of the steering wheel, a coating solution is applied to the mold cavity in advance in order to perform molding and painting simultaneously. In the method for manufacturing a steering wheel, the coating solution is formed in the mold cavity by boiling the paint solution in the mold cavity in which the core metal of the steering wheel is set, and increasing the volume at the time of boiling and breaking bubbles. Manufacturing method of a steering wheel. 6. The method of manufacturing a steering wheel according to claim 5, wherein the filling material is a urethane material, and after forming a coating layer on the mold cavity, the urethane material is mixed and injected into the mold cavity. And subjecting the core of the steering wheel to a molding resin molding by reaction hardening. 7. The method of manufacturing a steering wheel according to claim 5, wherein a pressure inside the mold cavity is reduced. 8. An insert molded product in which a filler material is injected into a mold cavity in which an insert member is set, and the insert member is molded, wherein a coating film formed on the surface of the filler material with a substantially uniform thickness. And an intermediate layer formed of the same material as the coating film between the insert member and the filling material. 9. The insert-molded product according to claim 8, wherein the filling material is a urethane material that reacts and hardens in a mold cavity. 10. A steering wheel in which a filling material is injected into a mold cavity in which a core metal of a steering wheel is set, and the core metal is molded. The steering wheel is formed with a substantially uniform thickness on the surface of the filling material. A steering wheel, comprising: a coating film; and an intermediate layer formed of the same material as the coating film, between a core metal of the steering wheel and the filling material. 11. The steering wheel according to claim 10, wherein the filling material is a urethane material that reacts and hardens in a mold cavity.