JP2001162656A - Injection molding tool and method for manufacturing patterned molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heat only a necessary part of a film after start of mold locking. SOLUTION: In an injection molding tool comprising a mold A having a cavity-forming depressed part to which the film sticks close, and a cavity- forming projected part which comes into the cavity-forming depressed part when the mold is locked, a film heating part is constituted so as to be formed in the cavity-forming projected part of the mold B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to automobile interiors such as console panels, armrests, coin trays, door trims, center pillars, wheel caps, meter panels, dashboards, switch bases, operation buttons, instrument panels, various bezels, and the like. Exterior parts,
The present invention relates to a method of manufacturing a molded product with a picture, such as a front panel and operation buttons of AV equipment, or a panel and operation buttons of home electric appliances such as a washing machine, a rice cooker, and a water purifier, and an injection mold applicable to the manufacturing method. .

[0002]

2. Description of the Related Art In a method of manufacturing a molded article with a picture, a film is introduced into a mold for injection molding, and after heating the film, the film is vacuum-sucked and brought into close contact with a cavity forming surface of the mold, and the mold is closed. In some cases, a molten resin is injected into a cavity of a post-injection mold to integrate a film and a molded product. The reason for heating the film is to soften the film so that the film can be stretched so that the film uniformly adheres to the entire surface of the cavity forming recess of the mold. However, the degree of softening of the film must be increased in a portion of the cavity forming concave portion having a large bending angle as compared with other flat portions (hereinafter, referred to as a flat portion).
The portion of the film that must be brought into close contact with a portion having a large bending angle in such a cavity forming concave portion is referred to as a “required portion”. ). Otherwise, tearing of the film, discoloration of the white color, cracking of the ink layer formed on the film, and the like may occur only in the necessary portions (see FIG. 10). Means for heating only a necessary portion of the film include (1) means for increasing the temperature of the injection mold itself only in a portion having a large bending angle in the cavity forming recess. (2) There is a means for blowing hot air from a heating plate inserted between molds only to necessary portions of the film.

[0003]

However, since the means (1) raises the temperature of the injection mold itself, the heat conduction of the metal results in a temperature rise in a wide range of the mold. This means that a wide area other than the necessary part of the film is heated. (2)
According to the above method, the timing of heating the film is limited before the closing of the injection mold is started, so it is difficult to maintain the degree of softening of a necessary portion of the film after the heating plate is withdrawn. Was. In any of the above cases, only the necessary portion of the film cannot be heated after the mold closing is started. As a result, in the portion having a large bending angle in the cavity forming concave portion, the film is torn, discolored, or formed on the film. However, the problem of the occurrence of cracks or the like in the ink layer could not be solved (see FIG. 10).

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an injection mold according to the present invention comprises a mold A having a cavity forming recess to which a film adheres, and a cavity forming recess when the mold is closed. And a mold B having a cavity forming convex portion to be inserted.
A film heating section is formed on the cavity forming projection.

[0005] In the invention of the injection mold, a vacuum suction hole may be formed in the parting surface of the mold A or the cavity forming recess.

The method of manufacturing a molded article with a pattern according to the present invention is a method of manufacturing a molded article with a pattern using any one of the above-mentioned injection molds. After the film is introduced, between the start of closing the mold A and the mold B and the injection of the molten resin, the film is heated by the hot air or the heat ray from the film heating section formed on the cavity forming projection of the mold B. After heating and closing the mold, a molten resin is injected into the cavity to integrate the film and the molded product.

In the manufacturing method described above, the film may be heated, the film is pressed against the parting surface by the clamp plate, and the film is brought into close contact with the cavity forming recess by vacuum suction.

In the invention of the above manufacturing method, the heating method using hot air may be a hot air blowing method.

In the invention of the above manufacturing method, the heating method using a heat ray may be a heat ray irradiation method using a halogen lamp.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a mold for injection molding and a molded product with a picture according to the present invention will be described with reference to the drawings.

First, an injection molding die of the present invention and a film applicable to the present invention will be described. The injection mold basically includes a mold A having a cavity forming recess 2 to which the film 1 is in close contact, and a mold B having a cavity forming protrusion 3 which enters the cavity forming recess 2 when the mold is closed. (See FIGS. 1 to 6). In the injection mold, after introducing the film 1 between the mold A and the mold B, the film 1 is heated, and after the mold closing is completed, the molten resin 7 is injected into the cavity 6, and the heat of the molten resin 7 is reduced. The film 1 and the molded product 8 are integrated with each other by pressure and cooling after injection. When the injection mold is composed of a fixed mold and a movable mold, the mold A may be a fixed mold and the mold B may be a movable mold. Alternatively, the mold B may be a fixed mold. The combination in which the mold A is a movable mold may be used. In addition, the molds for injection molding include the mold A and the mold B in addition to the mold A and the mold B.
May be used to form a part of the surface forming the inner surface of the cavity by being sandwiched between the mold and the intermediate mold.
The mold A may have a clamp plate 10 for pressing the film 1 against the parting surface 9. Examples of the clamp plate 10 include a frame-shaped clamp plate, a planar “one” type clamp plate, and a planar substantially “U” type clamp plate. The mold A may have the vacuum suction holes 11. Some of the vacuum suction holes 11 are formed in the cavity forming concave portion 2 and the parting surface 9. This is because the film 1 pressed against the parting surface 9 of the mold A is attracted to the surface of the cavity forming recess 2 of the mold A. The injection gate 12 for the molten resin 7 may be formed in the mold A or may be formed in the mold B. 1 to 6, the molten resin injection gate 10 is formed on the mold B. In this case, the molten resin flows from the passage 13 inside the mold A to the hook-like passage 13 inside the mold B.
And then filled between the film 1 and the mold B. The mold B may be provided with an ejector pin 14 for removing the molded product with a picture by protruding (see FIG. 6).

A film heating section 15 is formed on the cavity forming projection 3 of the mold B. The formation position of the film heating portion 15 is determined by the portion 1 of the cavity forming convex portion 3 of the mold B where the bending angle of the cavity forming concave portion 2 of the mold A is large.
The part approaching 6 is particularly preferred. Even when the closing of the mold A and the mold B is close to completion or after the completion, the film 1
This is because only the necessary parts can be heated without waste and the degree of softening of the film 1 can be increased. The specific formation position of the film heating unit 15 is the mold B
Of the cavity forming projections 3, there is a portion close to the tip of the tip surface or side surface, a corner portion, or the like. Further, the film heating unit 15 may be embedded under the surface of the cavity forming protrusion 3 of the mold B, that is, in the lower surface layer within a range where the hot air or the heat ray reaches the film 1 (see FIG. 11).

As the film heating unit 15, there are a hot air blowing means, a heat ray irradiation means, and the like. The hot air blowing means sends out heat generated from a heat radiation source by wind. As the heat radiation source, there are a cast heater, a far infrared heater, a heating wire heater and the like. In order to prevent the molten resin 7 from entering the hot air passage 22 for blowing out the hot air, the pin 18 is sandwiched in the hot air passage 22 (see FIG. 8), and a plurality of split molds 19 are combined. (See FIG. 9). Further, a sintered metal having fine holes may be used (see FIG. 7). Pin 18 above
, The gap between the split molds, or the gap between the holes of the sintered metal is preferably set to be 0.03 mm to 0.2 mm. In addition, the sintered metal has a large porosity, has a pressure resistance against the injection pressure of the molten resin, and has an excellent ventilation effect because of the air permeability, and does not penetrate the molten resin 7 and fits in the mold. Because it is only, the structure is simple.
As a heat ray source used as the heat ray irradiation means, there is a halogen lamp or the like. Halogen lamps are effective because the speed of raising the temperature of the film is high, and only a predetermined portion of the film can be heated.

The film 1 is obtained by sequentially laminating a pattern layer, an adhesive layer and the like on a base sheet, and there is a so-called insert film which does not peel off the base sheet after the molten resin 7 is adhered to the film 1. . The film 1 is formed by sequentially laminating a release layer, a picture layer, an adhesive layer, and the like on a base sheet, and there is also a so-called transfer film that peels the base sheet after the molten resin 7 adheres to the film 1. . Examples of the material of the base sheet include polyethylene terephthalate, polypropylene, and acrylic. The picture layer is a layer that imparts decorativeness and functionality to the surface of the molded article. The picture layer includes a normal printed pattern and a conductive pattern formed of a conductive material. The picture layer can be formed with a resin binder and a pigment or a dye. The picture layer may use a resin binder and a metal pigment or an inorganic pigment having a masking property. The picture layer may be composed of a metal vapor-deposited layer to give a metallic luster. The adhesive layer is a layer for bonding the film and the molded product. For the adhesive layer, a heat-sensitive or pressure-sensitive resin suitable for the material of the molding resin is appropriately used. For example, when the molten resin is an acrylic resin or a urethane resin, a vinyl chloride-vinyl acetate copolymer resin or an acrylic resin may be used as the adhesive layer. The picture layer and the adhesive layer are formed by various printing methods. The adhesive layer may use a resin film.

A method for manufacturing a molded article with a pattern of the present invention using the above-described injection mold will be described with reference to the drawings.

First, a film 1 is introduced between a mold A and a mold B of an injection mold (see FIG. 1). As a specific example, first, a film 1 unwound from a film roll of an unwinding roll means above an injection molding die.
Is gripped by the film gripping means. The leading end of the leading end of the film 1 in the introduction direction is in a state of protruding from the film holding means. The film gripping means is fixed to the tip of a band, a wire, a ball screw or the like. Next, a belt-shaped body, a wire, a ball screw, or the like is driven in the longitudinal direction, and the film 1 is moved.
Is moved downward, and the film 1 is introduced between the mold A and the mold B. The film holding means holding the film 1 is passed over the cavity forming recess, and the leading end of the film 1 protruding from the film holding means is transferred to a temporary fixing plate located further downstream of the cavity forming recess. Next, the film gripping means once releases the film 1, and only the film gripping means retreats above the cavity forming recess 2 while leaving the film. The retracted film gripping means grasps the leading end of the next film 1 in the introduction direction while the injection molding is being performed.
Prepare for the next introduction operation.

Next, the film 1 is pressed against the parting surface 9 by the clamp plate 10 (see FIG. 1). This step may be performed as needed. For example, first, the film roll of the unwinding roll means is reversely rotated to generate tension on the film 1 between the film 1 and the temporary fixing plate, and then the film 1 is clamped on the parting surface 7 of the mold by the clamp plate 10. Hold down. The mold for pressing the film 1 may be the mold A or the mold B having the injection gate 12. At the time of pressing, that is, simultaneously with or after pressing, the pressed film 1 is cut from the film roll with a heat cutter, and the clamp plate 1 is pressed.
The single film 1 may be pressed between 0 and the parting surface 9.

Next, if necessary, the film 1 pressed against the parting surface 9 by the clamp plate 10 is heated (see FIGS. 1 to 4). That is, during the period from the start of closing the mold A and the mold B to the injection of the molten resin 7, the film 1 is heated by the hot air or the heat ray from the film heating unit 15 formed on the cavity forming protrusion 3 of the mold B. Heat. Mold B
Film heating section 1 formed on cavity forming projection 3
Examples of the heating start time, heating end time, and temperature setting of No. 5 include the following specific examples (see FIGS. 1 to 4).

A film 1 made of an acrylic resin and having a thickness of 125 μm is used.
The case where the approach distance to the mold 5 is 2 mm when the mold closing is completed will be described. First, after the film 1 is pressed against the parting surface 9 by the clamp plate 10, the film 1 is heated by the heating plate 21 having a heater temperature of 300 ° C. so that the surface temperature of the film 1 becomes 110 ° C. (see FIG. 1), and vacuum suction is performed. As a result, a part of the film 1 is brought into close contact with a part of the cavity forming recess 2 of the mold A (in FIG. 2, a part of the film is brought into close contact with a part of the bottom surface of the cavity forming recess 2). Such a phenomenon occurs because the softening of the film 1 is insufficient.
This is because it cannot follow the corner of the cavity forming concave portion 2. Next, the mold closing is completed while the vacuum suction is maintained (see FIGS. 3 and 4). After the mold closing is completed, hot air 2 of 150 ° C.
Blow out three. As a result, the film 1 floating on the portion 16 having a large bending angle of the cavity-forming concave portion 2 of the mold A is sufficiently softened, so that the film 1 comes into close contact with the entire surface of the cavity-forming concave portion 2 by vacuum suction. Film heating unit 1
When the hot air from 5 is strong, vacuum suction may not be required in some cases. Note that hot air may be continuously blown from the film heating unit 15 of the mold B during the period from when the mold is closed to when the mold is completely closed. In this case, the heating efficiency of the film is improved because the hot air hits the film 1 even at the stage before the mold closing and before the mold closing is completed.

Next, after the mold is closed, the molten resin 7 is injected into the cavity 6, and the film 1 and the molded product 8 are integrated (see FIG. 5). As a specific example, the mold A and the mold B are closed, the film 1 is sandwiched, the molten resin 7 is injected from the injection gate 12, and the adhesive layer of the film 1 and the molten resin
The melted resin 7 is cooled and solidified while the film 1 is in contact, and the film 1 adheres to the molded product 8 (see FIG. 5). When a so-called transfer film is used as the film 1, the base sheet is peeled off after the film 1 and the molded product 8 are integrated. As the material of the molten resin 7, polystyrene resin,
An ABS resin, a polycarbonate resin, a polypropylene resin, a polyethylene resin, or the like can be used. Finally, the mold A and the mold B are opened, the clamp plate 10 is separated from the mold, and the film 1 is adhered to the molded product 8 by the protrusion by the ejector pin 14 provided on the mold B. The product is taken out (see FIG. 6). In FIGS. 1 to 6, the molten resin 7 passes through the hook-shaped passage 13 inside the mold B from the straight passage 13 inside the mold A, and then the molten resin 7 moves between the film 1 and the mold B. It has a mold structure filled between them. For this reason, when the molded product 8 cooled and solidified is ejected by the ejector pin 14, the hook-shaped portion of the hook-shaped gate portion molded product 24 fixed to the molded product 8 is caught by the mold, and the impact causes the molded product 8 and the film. 11 may be peeled off. To prevent such inconvenience, the inclined core 25 (see FIG. 6), which is a portion that is hooked on the hook-shaped portion of the hook-shaped gate molded product 24 at the time of opening the mold, and the inclined core 25 and the falling pin are used. The pin can be configured to retreat from the hook-shaped portion of the hook-shaped gate portion molded product 24. When the cooled and solidified product 8 is ejected by the ejector pin 14, the hook-shaped gate portion molded product 24 This is effective because it is possible to prevent the hook-shaped portion from being caught on the mold.

[0021]

According to the present invention, in short, only the necessary portion of the film can be heated between the start of closing the injection mold and the injection of the molten resin. Therefore, according to the present invention, since the film can be heated even after the closing of the injection mold is started, it is possible to maintain the degree of softening of a necessary portion of the film even after the heating plate is withdrawn. Becomes Even if the degree of softening by the heating plate disappears, the film can be heated again after the mold closing is completed, so that it is easy to reproduce the softening of the film. Further, since the heating can be performed in the vicinity of the necessary portion of the film, the film is not heated over a wide area beyond the necessary portion of the film, and only the necessary portion can be reliably and efficiently softened. As a result, it is possible to solve the problem of tearing of the film, discoloration of the white color, cracking of the ink layer formed on the film, and the like in the portion having a large bending angle in the cavity forming concave portion.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of an injection mold according to the present invention and one step of a method of manufacturing a molded article with a picture.

FIG. 2 is a cross-sectional view showing one embodiment of an injection mold according to the present invention and one step of a method of manufacturing a molded article with a picture.

FIG. 3 is a cross-sectional view showing one embodiment of an injection mold according to the present invention and one step of a method of manufacturing a molded article with a picture.

FIG. 4 is a cross-sectional view showing one embodiment of an injection mold according to the present invention and one step of a method of manufacturing a molded article with a picture.

FIG. 5 is a cross-sectional view showing one embodiment of an injection mold according to the present invention and one step of a method of manufacturing a molded article with a picture.

FIG. 6 is a sectional view showing one embodiment of an injection mold according to the present invention and one step of a method for producing a molded article with a picture.

FIG. 7 is a sectional view showing one embodiment of the injection mold according to the present invention.

FIG. 8 is a sectional view showing one embodiment of the injection mold of the present invention.

FIG. 9 is a sectional view showing one embodiment of the injection mold according to the present invention.

FIG. 10 is a perspective view for explaining a conventional technique and its problems.

FIG. 11 is a sectional view showing one embodiment of the injection mold according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Film 2 Cavity forming concave part 3 Cavity forming convex part 6 Cavity 7 Molten resin 8 Molded product 9 Parting surface 10 Clamp plate 11 Vacuum suction hole 12 Injection gate 13 Passage 14 Ejector pin 15 Film heating part 16 Large bending angle part 18 Pin 19 Split mold 20 Sintered metal 21 Heating plate 22 Hot air path 23 Hot air 24 Hook-shaped gate part molded product 25 Inclined core

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshikazu Kobe 3, Mibuhanai-cho, Nakagyo-ku, Kyoto-shi, Kyoto Inside Nihon Photo Printing Co., Ltd. Address Nihon Photo Printing Co., Ltd. F-term (reference) 4F202 AA11 AA13 AA28 AD09 AD10 AH17 AH42 CA11 CB01 CB19 CK41 CN25 CQ01 CQ06 4F206 AA11 AA13 AA28 AD09 AD10 AH17 AH42 JA07 JB19 JN25 JN43 JQ81

Claims (6)

[Claims] 1. An injection molding die comprising: a mold A having a cavity forming concave portion to which a film is in close contact; and a mold B having a cavity forming convex portion which enters the cavity forming concave portion when the mold is closed. Wherein a film heating section is formed on the cavity forming projection. 2. The injection mold according to claim 1, wherein a vacuum suction hole is formed in a parting surface or a cavity forming recess of the mold A. 3. A method of manufacturing a molded article with a picture using the mold for injection molding according to claim 1, wherein a film is first placed between the mold A and the mold B. After the mold is introduced, the film is heated by hot air or heat rays from the film heating section formed in the cavity forming protrusion of the mold B during the period from the start of closing the mold A and the mold B to the injection of the molten resin. And a method of injecting a molten resin into the cavity after completion of the mold closing to integrate the film and the molded product, thereby producing a molded product with a picture. 4. The method according to claim 3, wherein the film is heated, the film is pressed against the parting surface by a clamp plate, and the film is brought into close contact with the cavity forming recess by vacuum suction. 5. The method for manufacturing a molded article with a picture according to claim 3, wherein the heating method using hot air is a hot air blowing method. 6. The method of manufacturing a molded article with a picture according to claim 3, wherein the heating method using a heat ray is a heat ray irradiation method using a halogen lamp.