JP2000117782A - Mold for foil decorating simultaneously with injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily escape a gas by forming the entirety or a part of the cavity face of the side opposite to the side with which a decorated sheet comes into contact, of a porous material, on the cavity face. SOLUTION: The half, corresponding to the first surface, of a mold is a female half Mb with a recessed part, and a decorated sheet S is a mold on the side where a decorated sheet S comes into contact with a cavity face 1. On the other hand, another half on the opposite side, of the mold is a male half Ma with a projecting part, and a part of the cavity face 1 is formed of a porous material 2. This part is a part including a final resin filling position and the porous material 2 is embedded in the male half Ma in such a manner that a part of the material 2 forms the cavity face 1. In addition, when the resin is injected through a gate G, a gas inside the cavity is allowed to escape to the outside through the porous material 2. The area and depth of the cavity face 1 formed with the porous material 2 are properly decided. Thus it is possible to allow an easy escape of the gas from the cavity during injecting the resin and prevent the imperfect gas escape from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a mold for simultaneous painting with injection molding. In particular, the present invention relates to a mold in which gas in a cavity is easily released at the time of injection.

[0002]

2. Description of the Related Art Conventionally, in accordance with an injection molding simultaneous painting method, a painting sheet having a decoration or the like applied to the surface of a resin molded product is integrally formed at the same time as molding to form a painting molded product in various forms. Have been done. For example, Japanese Patent Publication No. 50-1913
In Japanese Patent Application Publication No. 2 (1993) -1995, a painted sheet made of a thermoplastic resin is vacuum-formed using a female mold provided with air holes for vacuum molding, and then the male and female molds are clamped to form a molten resin in both molds. There is disclosed a method of injecting into a cavity and integrating a painting sheet with the outer surface of a resin molded product simultaneously with injection molding. The simultaneous injection molding painting method of this aspect is a method in which vacuum molding and injection molding are combined, and a complicated curved surface can be patterned. Note that there are two types of painted sheets: a laminate type and a transfer type.In the former, the painted sheet itself is laminated on a resin molded product and painted, and in the latter, only the base sheet of the painted sheet is peeled off and the transfer layer is formed. It is transferred to a resin molding and painted.

[0003] In a normal injection molding die that does not use a painting sheet, gas in the cavity escapes from a gap around an ejector pin provided on the cavity surface corresponding to the back side surface of the painting product, and gas remains. The position of the air vent is devised so that the insert block is provided at an easy position and escapes from the surrounding gap.
However, in the case of the injection molding simultaneous painting mold, in the form of the normal injection molding simultaneous painting method, the painting sheet supplied between the female mold and the male mold uses the injection molding simultaneous painting mold as the vacuum molding mold. And then injection-molded along the cavity surface of one mold (usually a female mold). For this reason, it is not possible to provide an air vent for allowing gas to escape on the cavity surface on the side along which the painted sheet is brought into contact. Therefore, in the case of the mold for simultaneous painting with injection molding, the other mold (usually a male mold) having a cavity surface which does not allow the painting sheet to come into contact, and the use of a parting surface as an air vent have been devised. In some cases, the mold temperature is set higher in the male mold than in the female mold to control the flow of the resin so as to allow time for the gas to escape from the parting surface.

FIG. 2 is a cross-sectional view conceptually showing a gas reservoir 3 which is likely to be generated when the air vent is incomplete in a conventional injection molding and simultaneous painting mold. FIG. 3 is an enlarged sectional view of a main part of the gas reservoir 3. FIG. 3 shows a case where the gas reservoir 3 is generated at a position in contact with the painting sheet S. In such a case, as shown in the cross-sectional view of FIG. 4, in the unpainted resin P caused by the gas pool, in the obtained painted molded product P, a defective portion is formed in a part of the injected and solidified resin molded product 5. 4 results. For this reason, in the case of the laminated sheet in which the painted sheet is laminated and integrated with the resin molded product 5 in the defective portion 4, the painted sheet S does not adhere to the resin molded product 5, and poor adhesion occurs. Further, when the painting sheet is a transfer sheet, the transfer layer that transfers to the resin molded product is not in close contact with the resin molded product at the defective portion 4, so that a transfer failure due to poor adhesion occurs. In the poor adhesion portion, the heat-softened painting sheet may swell toward the cavity (deficient portion 4), or may be displaced and wrinkled by the flow of the resin. As a result, poor painting results.

[0005]

As described above, in the case of the mold for simultaneous painting with injection molding, it is necessary to devise an air vent in comparison with a normal injection molding die. And even if the parting surface is used for air venting, the painted sheet is usually fixed to the parting surface.
It was not easy to release gas from the parting surface as compared with a normal injection mold. Therefore, it is possible to lower the mold clamping force to slightly reduce the contact, or to cut the parting surface near the final filling position by about 10 to 50 μm compared to other parts to make it easier for gas to escape. Has a problem that resin burrs are easily generated. On the other hand, it is very difficult to stably control the resin flow by controlling the flow of the resin based on the temperature difference between the male and female molds.

Accordingly, an object of the present invention is to provide a mold for simultaneous injection molding and painting, in which gas is less likely to escape than a normal injection molding die, in which gas is easily escaped.

[0007]

Therefore, in order to solve the above problems, in the injection molding simultaneous painting mold of the present invention, after inserting a painting sheet between a pair of molds, both molds are clamped, and both molds are clamped. Inject the resin in the fluid state into the cavity formed by the mold, and integrate the painted sheet and the resin molding at the same time as molding,
In the mold used for the simultaneous injection molding and painting method for obtaining a painted molded product, the cavity surface of the mold opposite to the mold on which the painting sheet is in contact with the cavity surface is entirely or partially formed of a porous material. Type of configuration. As a result, the gas in the cavity at the time of resin injection is easily released by the porous material, so that a defective gas escape can be prevented. Therefore, gas accumulation does not occur, generation of a defective portion of the resin molded product,
Painting, such as poor adhesion of the painted sheet (in the case of a laminate sheet) or poor adhesion (transfer) of the transfer layer (in the case of a transfer sheet), which occurs because the painted sheet does not adhere to the resin molded product in the gas reservoir part. Prevents product defects due to poor painting that is not achieved in the department.

The position where the porous material is formed in the cavity surface may be one or both of the final filling position of the resin and the position where the weld line is generated. This allows the gas in the cavity to escape efficiently. This is because these portions correspond to the downstream side of the flow of the resin in the cavity.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

[Injection Mold Simultaneous Painting Mold] First, in general, the injection molding simultaneous painting mold is a mold used in the normal injection molding simultaneous painting method. The painted side of the product is the front side, and the mold corresponding to the front side has a recessed female mold (cavity mold)
The female mold is a mold on the side where the painted sheet is in contact with the cavity surface, and the mold on the opposite side is a male mold (core mold) having a convex portion.
Becomes Then, the resin is usually injected from the male mold side. However, conversely, there may be a case where the side corresponding to the front side of the painted molded product is a male type having a protrusion. Therefore, the mold on the side where the painted sheet contacts the cavity surface is not necessarily a female mold. However, in the following description, it is assumed for convenience that the type is a female type.

First, FIG. 1A shows a certain painted molded product P.
FIG. 4 is a plan view showing the relationship between the external shape of the device and the gate G. FIG. 1B shows a case where the X-X line including the position where the cavity surface is formed by the porous material is taken as a cutting line with respect to the decorative molded product P of FIG. 1A. It is sectional drawing after completion of resin filling. In the case of FIG. 1B, a part of the cavity surface 1 of the mold Ma (corresponding to a male mold) is formed of the porous material 2. The portion of the cavity surface formed of the porous material 2 is a portion including the final filling position of the resin. The porous material 2 is embedded in a mold Ma so that a part thereof forms a cavity surface. On the other hand, the mold Mb (corresponding to a female mold) is a mold on the side where the painted sheet S contacts along the cavity surface. In this way, if the cavity surface 1 of the mold on the side where the painting sheet S does not contact the cavity surface is formed by the porous material 2,
When the resin is injected from the gate G, the gas in the cavity can escape to the outside through the porous material 2 (see the arrow in the porous material 2 in the drawing).

The width of the cavity surface formed by the porous material and the depth of the porous material from the cavity surface may be appropriately determined. FIG. 1 is a conceptual diagram, and the size (width, depth) is conceptually drawn to the last. Further, as shown in FIG. 1B, the surface formed by the porous material may be extended from the cavity surface to the parting surface. In this case, it is not necessary to precisely align the position formed of the porous material with the final filling position of the resin, and the design of the mold is facilitated.

Usually, it is preferable to provide the portion of the cavity surface formed of the porous material in a portion including the final filling position of the resin. Therefore, the position of the porous material is shown in FIG.
In the case where there is one gate G at the center of the substantially elliptical shaped molded product M shown in (A), in the outer peripheral portion of the molded product, there is an X-X line that is in the major axis direction of the ellipse. Since the intersecting portion is the final filling position, it may be provided at a position including at least that portion. The position of the cavity surface formed of the porous material is usually determined by the mold Ma and the mold Mb in which gas easily accumulates in the mold Mb on the male mold side as shown in FIG.
It is provided near the parting line where both types contact. It is also preferable that the position of the porous material is a position where a weld line is generated. Since the weld line is the junction of the resin flowing through the cavity, the gas that has been pushed away by the resin comes together.If it is possible to completely fill the resin while allowing it to escape smoothly, the final filling This is because it is possible to eliminate gas that can accumulate at the position. Of course, if some gas remains at the end, it is preferable to form the cavity surface with a porous material at the final filling position together with the weld run. Of course, the entire cavity surface of the male mold may be formed of a porous material. However, it is sufficient if the desired air vent performance is satisfied by providing a part of the cavity surface.

The gas that has entered the inside of the porous material from the surface forming the cavity surface of the porous material may escape from the side or bottom surface of the porous material to the outside of the mold. For this purpose, the side and bottom of the porous material may be extended to the side and bottom of the mold and exposed, but in terms of the mechanical strength of the mold, etc., the porous material is used only for the necessary parts. It is better to do. For this purpose, a passage leading to the outside of the mold may be connected to the side or bottom surface of the embedded porous material as an air vent (not shown). However, since the air vent does not come into contact with the injection resin, the gap may be wide. Alternatively, a vacuum pump may be further connected to the air vent to forcibly exhaust the gas.

As the porous material, air permeability, mechanical strength,
There is no particular limitation as long as the material has heat resistance and the like. In addition, the surface forming the cavity surface may be any surface as long as a vent hole large enough to prevent the injected resin from entering the interior and solidifying is opened. In some cases, a mark of the porous material is formed as a rough surface on the resin molded product in contact with the porous material, but the portion is usually invisible or has no problem in design even if touched. This is almost no problem, so there is no problem.
Such a porous material is made of, for example, iron, nickel, or the like.
The porous material may be a material obtained by making the metal porous by a known method such as a porous electroforming method or a powder sintering method. Alternatively, porous ceramics or the like may be used.

For example, a porous electroforming method is disclosed in
This is a method of obtaining a plating film as a porous layer as disclosed in Japanese Patent No. 52692. Incidentally, JP-A-60-15
No. 2692 discloses a method disclosed in Japanese Patent Application Laid-Open No. HEI 6-92, for the purpose of preventing the occurrence of pinholes in a plating film by a normal electroforming method.
A method of adding a surfactant such as sodium lauryl sulfate to the plating solution, while positively generating pinholes by plating without adding a surfactant to make the plating film porous. It is.

The porous ceramic preferably has a pore size of 5 as disclosed in JP-B-7-102588.
It is distributed in the range of 0 to 150 μm and has an air permeability of ³ to 25 m ^3.
/ Cm ² · s is good. As such a porous ceramic, for example, a metal powder and a fiber with respect to a ceramic powder, or a material obtained by mixing and sintering one of them can be used. Specifically, a product name “Porcelax” sold by Shinto Kogyo Co., Ltd. can be used. The higher the air permeability, the better the gas flow, but the lower the mechanical strength. The lower the air permeability, the better the mechanical strength, but the worse the gas flow. The pore size depends on the quality of the surface required of the molded product (usually the surface that forms the back surface of the molded product). The street gets worse.

The material of the part other than the porous material of the mold for simultaneous painting with injection molding may be a conventionally known material. For example, a metal or metal alloy such as iron or iron alloy, or a non-metallic material such as ceramics may be used.

The mold for simultaneous painting with injection molding of the present invention has a structure in which at least a part of the cavity surface is formed of a porous material as an air vent, but has a structure in which other conventionally known air vent means are provided. May be. Further, similarly to the conventionally known molds, a mold divided into a plurality of parts may be used for each of the female mold and the male mold. In the case of the shape and the gate position of the painted product illustrated in FIG. 1, the final filling position of the resin selected as the position of the porous material was the outer peripheral portion of the painted product. However, needless to say, even when the position of the porous material is selected as the final filling position, the final filling position is not necessarily the outer peripheral portion of the molded product depending on the shape of the molded product.

[Injection Simultaneous Painting Method] A simultaneous injection molding simultaneous painting method in which the injection molding simultaneous painting mold of the present invention can be used will be described here. Injection molding simultaneous painting method is described in JP-B-50-19132, JP-B-43-27.
No. 488, JP-A-6-315950, JP-B-2-42080, etc., after inserting a sheet with a picture between a pair of molds in a mold open state, the molds are clamped. In this method, a resin in a flowing state is injected into a cavity formed by both molds, and simultaneously with molding, the painted sheet and the resin molded product are integrated to produce a painted molded product.

There are various types of simultaneous injection molding painting methods.
For these various forms, the injection molding simultaneous painting mold of the present invention can be used. As various forms of the simultaneous injection molding painting method, for example, either a form in which pre-forming of a painted sheet is not performed or a form in which pre-forming is not performed may be used. Also, the prepainted sheet may or may not be preheated. Note that the prepainted sheet is usually preheated during preforming. of course,
When the drawing sheet has a large drawing, it is preferable to perform preforming. On the other hand, when the drawing sheet has a small aperture, the drawing sheet can be formed by the resin pressure of the resin in the flowing state to be injected. At this time, if the drawing is small, the painted sheet may be formed only by the resin pressure of the resin in the flowing state filled into the mold at the same time as the resin injection without the preliminary molding. Further, even when the painted sheet is formed by the resin pressure, the painted sheet may utilize the heat of the injection resin without preheating. In addition, the preforming of the painted sheet is usually performed by simultaneously using the injection molding simultaneous painting mold and the vacuum forming mold, but before supplying the painted sheet between the molds,
Preforming such as vacuum forming the picture sheet with another vacuum forming die outside the die may be used. In addition, the vacuum forming includes vacuum pressure forming.

Referring to the conceptual diagram of FIG. 5, the simultaneous injection molding painting method will be described in one form. In addition, the form described here is a form in which the painted sheet is heated and softened between the molds, pre-molded by vacuum molding with a simultaneous injection molding painting mold before clamping, and then the resin is injected by clamping. It is.

First, as shown in FIG. 5 (A), as a mold for simultaneous painting with injection molding, a mold Ma having a runner and a gate communicating with an injection nozzle, and a preforming mold for a sheet having a suction hole 41 on a cavity surface. Are used as a pair of molds of the mold Mb. These molds are made of metal such as iron or ceramics. Of course, in order to avoid complication of the drawing, for the sake of convenience, it is not shown in FIG. 5, but in the injection molding simultaneous painting mold of the present invention, a porous material is used at important points on the cavity surface. . Then, in the mold open state, both molds Ma,
The injection-molded simultaneous painting sheet S is supplied between Mb, and the painting sheet S is fixed to the mold Mb by pressing with a frame-shaped sheet clamp 42 or the like. At this time, it goes without saying that the adhesive surface side of the painted sheet is on the injection resin side on the right side of the drawing.
Next, the painted sheet is appropriately heated and softened by a heater (not shown) inserted between both molds. The heating is, for example, non-contact radiation heating, but may be contact heating. Then, the sheet is sucked from the suction hole and vacuum formed, and the prepainted sheet is preformed along the cavity surface of the mold Mb. In addition, vacuum forming may be vacuum press forming using both pressure and air, and this is also included. Next, the heater is retracted from between the two dies, the two dies are clamped as shown in FIG. 5B, and a cavity formed by the two dies is filled with a resin in a flowing state such as a heated and molten state. After the resin is solidified by cooling, the mold is opened and the molded product is taken out. In the case where the simultaneously painted sheet with the injection molding is a laminate sheet, if there is an unnecessary portion of the painted sheet, the painted sheet is laminated on the resin molded product and a painted molded article is obtained. When the painted sheet is a transfer sheet, the molded article is taken out with the base sheet left on the mold Mb side, or the molded article is taken out with the whole painted sheet laminated, and then the base sheet is taken out. Is removed to obtain a painted molded article in which only the transfer layer is laminated and painted.

[Painting sheet] The painting sheet that can be used for simultaneous painting by injection molding using the above-described mold for simultaneous painting by injection molding can be a conventionally known painting sheet as a transfer type or a laminate type. It is not particularly limited. Therefore, the painting sheet will be briefly described.

Transfer type painting sheet (transfer sheet)
Has a configuration in which a releasable sheet is used as a base sheet and a transfer layer is laminated on the base sheet. The transfer layer includes, for example, a decorative layer, an adhesive layer, and the like. In addition, there is a configuration in which a release layer is appropriately provided as a component of the transfer layer on the base sheet side of the transfer layer. The laminate type painting sheet (laminated sheet) has a configuration in which, for example, a decorative layer and an adhesive layer are sequentially laminated on a base material sheet. The adhesive layer may be omitted in both the transfer type and the laminate type.

As the base sheet, a resin sheet having moldability is typically used. As the resin sheet,
For example, olefin resins such as polyethylene, polypropylene and olefin thermoplastic elastomer, polyester resins such as polybutylene terephthalate and ethylene terephthalate isophthalate copolymer, vinyl chloride resin, acrylic resin, ABS (acrylonitrile-butadiene-styrene copolymer) A single layer of a sheet of a thermoplastic resin such as a resin, a polyamide resin, another thermoplastic elastomer such as a urethane-based elastomer, or a laminate of two or more layers of different materials is used. If the formability is satisfied, a sheet in which a resin such as a nonwoven fabric or a woven fabric is impregnated with a resin, a laminate in which the resin sheet is laminated, or the like is used. In the transfer type, a base sheet having a release layer is provided on the transfer layer side of the base sheet, if necessary, in order to improve the releasability from the transfer layer. The release layer is separated from the transfer layer together with the base sheet when the base sheet is peeled, and is removed. For the release layer, for example, a single substance or a mixture of two or more of silicone resin, melamine resin, polyamide resin, urethane resin, polyolefin resin, wax and the like are used. Further, in the case of a laminate type, a coloring agent such as a pigment is kneaded into a base sheet resin to perform a decoration treatment for making the base sheet colored transparent or colored opaque. In this case, the base sheet itself may form a decorative layer, and may be a picture sheet having a configuration of only the base sheet.

The decorative layer is formed on a part or the whole surface by a conventionally known method such as gravure printing, silk screen printing or offset printing, a pattern layer on which a pattern is printed with a material, or a metal such as aluminum or chrome by a known vapor deposition method. It is a formed metal thin film layer or the like. The pattern is arbitrary, such as a grain pattern such as a plate grain or a straight grain, a grain pattern such as marble or granite, a tile pattern, a brick pattern, a cloth pattern, a character, a geometric pattern, and a solid surface. The picture layer ink comprises a vehicle such as a binder, a coloring agent such as a pigment or a dye, and various additives appropriately added thereto. Binders include chlorinated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, polyester resins, urethane resins, acrylic resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, thermoplastic resins such as cellulose resins, and urethane resins. Or a thermosetting resin such as an epoxy resin is used alone or as a mixture of these resins. As a coloring agent such as a pigment or a dye, metal pigments such as titanium white, carbon black, red iron oxide, cobalt blue, graphite, phthalocyanine blue, isoindolinone, quinacridone, and aluminum powder, and pearlescent (pearl) pigments are used. Can be

In order to improve the adhesiveness to the injection resin, an easy-adhesion treatment such as corona discharge treatment and various known primer coatings, or a heat-sensitive adhesive layer may be applied to the back surface of the painted sheet. Known resins such as a thermoplastic resin and a thermosetting resin are used for the adhesive layer. For example, in thermoplastic resin,
Styrene resins or styrene copolymers such as polystyrene and poly-α-methylstyrene, acrylic resins such as poly (methyl) acrylate, ethyl poly (meth) acrylate and butyl poly (meth) acrylate, chlorinated polypropylene and the like Vinyl polymers such as chlorinated polyolefin resin, vinyl chloride resin, vinyl acetate resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, and rubber resins such as polyisoprene rubber, polyisobutyl rubber, styrene butadiene rubber, butadiene acrylonitrile rubber And one or a mixture of two or more thermoplastic resins such as polyamide resins. As the thermosetting resin, a urethane resin, an epoxy resin, or the like is used. In addition, in the painted sheet on which the adhesive layer is formed, the adhesive layer comes into contact with the injection resin at the time of injection, and a gas is more easily generated due to the volatilization of the residual solvent in the adhesive layer. However, the mold for simultaneous painting with injection molding of the present invention has good air vent performance, so that product defects such as poor adhesion of the painting sheet and poor transfer of the transfer layer hardly occur.

[Injection Resin] The resin to be injection-molded at the time of simultaneous injection-molding and painting using the injection-molding and simultaneous painting mold of the present invention may be any of those conventionally known in the simultaneous injection-molding and painting method. It can be used without any particular restrictions. Injection resin is
It is selected according to the required physical properties and cost of the product. For example, in the case of a thermoplastic resin, an ABS (acrylonitrile-butadiene-styrene copolymer) resin, an AS (acrylonitrile-styrene copolymer) resin, a styrene resin,
Polyvinyl chloride resin, acrylic resin, polycarbonate resin, or polyolefin resin such as polyethylene, polypropylene, polybutene, polymethylpentene, ethylene-propylene copolymer, ethylene-propylene-butene copolymer, olefin-based thermoplastic elastomer, etc. . In the case of a curable resin, a two-component curable resin, for example, a urethane resin, an unsaturated polyester resin,
An uncured resin liquid such as an epoxy resin. The thermoplastic resin is melted by heating and injected in a fluid state, and the curable resin is injected at room temperature or appropriately heated and flowed. Above all, in the present invention, due to gas accumulation, it is possible to prevent the occurrence of product defects such as poor painting due to poor adhesion of the painted sheet or poor transfer of the transfer layer, etc. For example, it is particularly effective in the case of a polyolefin resin such as polypropylene.

[Others] In the present invention, "painting"
The expression includes not only providing a visible pattern such as a pattern, a character, or a figure to a molded product, but also providing a pattern that is not visible or a functional layer such as a hard coating film or conductivity.
Known patterns such as a pattern layer formed by printing or the like and a metal thin film layer formed by vacuum evaporation or the like are examples of the pattern that can be visually observed. A pattern printed with fluorescent ink that emits fluorescence is used. The simplest painted sheet is an uncolored (transparent or opaque) mere resin sheet without any printing. In addition, the resin sheet is used for imparting surface physical properties such as improvement of surface strength and imparting a feeling of painting.

[0031]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.

[Examples and Comparative Examples] The painted molded article to be tested has a shape as shown in FIG. 1A, a width of 40 mm and a length of 40 mm.
As shown in FIG. 1 (B), the panel for vehicle interiors has a substantially trapezoidal cross section which has a substantially elliptical shape of 0 mm and which is convex on the surface side serving as a painting surface.

On the other hand, a sheet with a picture is made of methyl methacrylate-butyl methacrylate copolymer.
Back side of 5 μm thick acrylic resin film (injection resin side)
On the surface to become, the resin of the binder is a 1: 1 weight ratio mixture of acrylic resin and vinyl chloride-vinyl acetate copolymer,
The grain pattern is formed by multicolor printing of gravure printing using an ink composed of titanium white, phthalocyanine blue, polyazo red, and polyazo yellow. The sheet formed by the second printing was prepared.

As shown in FIG. 1 (B), the mold used as the mold for simultaneous painting with injection molding has a porous material 2 that includes a part of the outer periphery of the molded product at the final filling position of the resin. The block-shaped porous material 2 was nested at two locations on the male mold cavity surface.
The position of the gate G was set at one position substantially at the center of the back surface (male side) of the molded product. As the porous material, a porous metal ("Piporus", manufactured by Kobe Steel Ltd.) was used. The molds other than the porous material were both formed of carbon steel.

Then, simultaneous painting by injection molding is performed using the above-mentioned painting sheet and the above-mentioned mold for simultaneous painting by injection molding as described with reference to the conceptual diagram of FIG.
The painted molded article was manufactured. The painted sheet is first supplied between the male and female molds in the mold open state, then a hot plate of infrared radiation heating method is further inserted between the molds, the painted sheet is heated in a non-contact manner, and the female mold is vacuum formed. The painting sheet was preformed by vacuum molding as a mold, and the softened painting sheet was molded into a shape along the cavity surface of the female mold. Thereafter, the hot plate was retracted to a retracted position outside the mold, and both molds were clamped.
Next, a polypropylene-based resin was used at a resin temperature of 220 ° C.
The mold was injected into the cavity formed by both molds under the conditions of a mold temperature of 50 ° C. (both the female mold and the male mold) and an injection time of 2 seconds. After the resin was cooled and solidified, the mold was opened to obtain a painted molded product.

[0036] As a result, in the embodiment using the mold for simultaneous painting with injection molding using a porous material, the air vent was good, and no gas accumulation occurred, and a good product was obtained. The painted sheet was in close contact with the resin molded product up to the edge of the outer peripheral portion of the molded article, and the painted sheet was good without being lifted at the end.

However, as a comparative example, as shown in the cross-sectional view of FIG. 6, a conventional injection molding simultaneous painting mold in which a solid material (without air holes) 6 made of carbon steel is embedded instead of a porous material (air vent) Is temporarily provided on the parting surface), the gas escape was insufficient, and gas accumulation occurred at the end of the molded product. For this reason, in the gas accumulation portion, the resin was insufficiently filled, and the painted sheet floated up without adhering to the resin molded product 5.

[0038]

According to the present invention, by forming a part of the cavity surface with a porous material, the gas in the cavity at the time of resin injection can be easily escaped, so that a gas escape defect can be prevented. Therefore, gas accumulation is unlikely to occur, and the defective portion of the painted sheet (in the case of a laminated sheet), which occurs due to the occurrence of a defective portion of the resin molded product or the fact that the painted sheet does not adhere to the resin molded product at the gas accumulation portion, or the transfer layer This prevents product defects due to poor painting, such as poor adhesion (in the case of a transfer sheet), which is not partially achieved. Further, if the position where the porous material is provided is one or both of the final filling position of the resin and the position where the weld line is generated, the gas in the cavity can be efficiently released.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view conceptually illustrating a mold for simultaneous painting with injection molding of the present invention.

FIG. 2 is a cross-sectional view conceptually illustrating a gas reservoir that can occur due to an insufficient air vent in the case of a conventional injection molding simultaneous painting mold.

FIG. 3 is an enlarged cross-sectional view of a main part of a gas reservoir part of FIG. 2;

FIG. 4 is a cross-sectional view corresponding to FIG. 3 for explaining a defect in a painted molded product.

FIG. 5 is a conceptual diagram illustrating an example of a simultaneous injection molding painting method.

FIG. 6 is a sectional view conceptually illustrating the structure of a mold for simultaneous painting with injection molding used in a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cavity surface 2 Porous material 3 Gas reservoir 4 Defective part 5 Resin molding 6 Solid material 41 Suction hole 42 Sheet clamp Ma Injection molding simultaneous painting mold (male mold) Mb Injection molding simultaneous painting mold (female mold) G Gate P Painted product S Painted sheet

Claims (2)

[Claims] 1. After inserting a painted sheet between a pair of molds, both molds are clamped, and a resin in a flowing state is injected into a cavity formed by both molds. And a mold used in the simultaneous painting method for injection molding to obtain a painted molded product, wherein the cavity surface of the mold on the side opposite to the side where the painted sheet is in contact with the cavity surface is the whole or part thereof Is a mold for simultaneous painting with injection molding, which is formed of a porous material. 2. The mold for simultaneous injection molding and painting according to claim 1, wherein the position formed by the porous material is one or both of a final filling position of the resin and a position where a weld line is generated.