JPH11309750A - Method for injection molding in-mold decorating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid spoiling of the appearance of a product even when vent of gas is insufficient. SOLUTION: In a method for injection molding in-mold decorating wherein after an in-mold decorating sheet S is fed between a pair of molds A and B under mold opening condition, the molds are closed and a resin P is injected in the cavity 1 to perform the in-mold decorating on the surface of a molded article, a gas vent part 2 is provided at a separated position in such a way that the final filling position of the resin when the resin poured from a gate G is filled in the cavity 1 to become a molded article is at a position separated from the in-mold decorating sheet. Even if storage 3 of gas is generated, as it is separated from the in-mold decorating sheet, inferiority of in-mold decorating can be prevented from occurring. Preliminary molding of the in-mold decorating sheet by vacuum molding using a mold for injection molding can be performed before mold clamping.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simultaneous painting method for injection molding. In particular, the present invention relates to a method that does not cause poor painting and does not impair the appearance of the product even if the gas in the cavity during the injection is not sufficiently released.

[0002]

2. Description of the Related Art Conventionally, there are various injection molding simultaneous painting methods in which a pattern or the like is formed on the outer surface of a molded article simultaneously with the molding of the molded article. For example, in Japanese Patent Publication No. 50-19132, after a picture-formed sheet made of a thermoplastic resin is vacuum-formed by using a female mold having a vent hole for vacuum molding, both the male and female molds are clamped to melt the molten resin. There is disclosed a method of injecting into a cavity formed by both molds and integrating a painting sheet with an outer surface of a molded article 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 molded product for painting, and in the latter, only the base sheet of the painted sheet is peeled off to form the transfer layer. Transfer to the product and paint.

Here, an example of the simultaneous injection molding painting method is as follows.
This will be described with reference to conceptual diagrams illustrating the procedures in FIGS. In these drawings, air vent,
The illustrations of the runners and gates provided on the male mold and the air holes for vacuum forming provided on the female mold are omitted.

First, FIG. 4 shows a state before a painting sheet is supplied between dies. Type A is male and type B is female. The tip of the continuous band-shaped picture sheet S unwound from the roll R is
This is a state where the sheet is gripped from both sides by the transport chuck 21. From this state, the painted sheet is supplied between the mold A and the mold B,
The state after the supply of the painting sheet in FIG. 5 is set. That is, the transport chuck 21 grips the painted sheet S and moves downward, and the receiving chuck 22 located below the outside of the mold grips the front end of the painted sheet. Then, the transport chuck 21 releases the grip of the painting sheet, returns to the original position above the outside of the mold,
As a preparation for the next shot, the painting sheet is gripped on the upstream side of the mold B. Next, the frame-shaped clamp 23 always located between the molds moves forward to the mold B side (to the left in the drawing), and presses and fixes the painted sheet to the parting surface of the mold B around the four sides.

[0005] Next, a hot platen 2 for heating and softening the painted sheet.
4 enters between the molds in the mold open state from the retracted position outside the mold,
It moves to the position facing the painting sheet (see FIG. 5).
Then, as shown in FIG. 6, the hot platen 24 moves forward to a position where it comes into contact with the clamp 23 (to the left in the drawing) to heat and soften the painted sheet. Here, non-contact radiation heating is used.
At the same time as the hot platen moves to the heating position,
Cutter 25 made of nichrome wire or the like stretched over the hot platen
Comes into contact with the painting sheet, and cuts the painting sheet into one shot. Next, air is sucked in from a ventilation hole (not shown) provided in the mold B, and the painted sheet is vacuum-formed to preform the painted sheet along the cavity surface 27 of the mold B (see FIG. 6). . FIG. 7 shows a state after the hot platen 24 has been retracted to the retracted position outside the mold and both molds A and B have been clamped.

Then, a resin in a flowing state is injected and filled into cavities formed by both molds. Then, after the resin is solidified, the mold is opened, and the molded product is removed from the mold, whereby a painted molded product whose surface is painted with a painted sheet is obtained at the same time as molding. In the case of transfer, a substrate sheet made releasable,
If only the base sheet of the painted sheet including the transfer layer is peeled off from the molded product, the final painted molded product can be obtained.

[0007]

By the way, in the ordinary injection molding, the gas in the cavity escapes from the clearance around the ejector pin provided on the back side of the painted product, or the insert block is located at a position where the gas is likely to remain. The location of the air vent is devised so as to escape from the surrounding gap. However, in the case of the simultaneous injection molding painting method, as described above, in the simultaneous injection molding painting method of injection molding in a state where the painting sheet is supplied between the female mold and the male mold in advance, the painting sheet is one of the two. Injection molding is performed along the cavity surface of the mold (usually a female mold). For this reason, it is not possible to provide an air vent for allowing the gas to escape on the cavity surface along which the painted sheet extends. Therefore, the air vent can only use the other type (usually a male type) or parting surface which does not follow the painted sheet. Also, on the parting surface, the painted sheet is usually fixed on the parting surface, so it is easy to escape gas from the parting line by contacting the painted sheet (which is more flexible than the mold) with the parting surface. is not. Therefore, if the mold clamping force is lowered to make the gas easier to escape, resin burr is easily formed by molding, and the sink is increased. On the other hand, if the filling speed of the resin is reduced in order to secure a sufficient time for the gas to escape, the molding conditions are narrowed, and depending on the shape of the molded product, a short circuit in which the resin is not partially filled is likely to occur.

As described above, in the simultaneous injection molding and painting method, it is necessary to take care that the gas escape does not become incomplete as compared with the ordinary injection molding method. If the gas escape is incomplete, the resin will not be completely filled and a gas pool (accumulation) will occur. In the gas pool portion, poor adhesion between the painted sheet and the molding resin will occur in the case of a laminated type painted sheet, and the transfer type In the case of a painted sheet, poor adhesion of the transfer layer occurs. Further, the heat-softened painting sheet may swell toward the cavity, or may be displaced and wrinkled by the flow of the resin, resulting in poor molding.

[0009]

Therefore, in order to solve the above-mentioned problems, a simultaneous painting method for injection molding according to the present invention provides a painting sheet between a pair of molds which are in an open state, and then paints both molds. In the injection molding simultaneous painting method in which the mold is clamped, the resin in a flowing state is injected into the cavity formed by both molds, and the surface of the molded product is painted with the painted sheet at the same time as the molding, the inside of the cavity that becomes one molded product is gated. Injecting molding by providing a gas escape part at the distant position in the cavity so that the final filling position of the resin when filling the resin injected from the cavity becomes a position distant from the painting sheet. did. As a result, even if a gas pool occurs at the final filling position, since that portion is a portion away from the painted sheet, the painted sheet does not adhere to the molding resin due to the gas pool, for example, at the outer peripheral portion of the molded product. In addition, there is no product defect due to poor painting, such as poor adhesion of a painted sheet (in the case of a laminate sheet), poor adhesion of a transfer layer (in the case of a transfer sheet), etc. Further, even when the gas cannot be completely escaped, it does not affect the painted surface, so that a wide range of injection molding conditions can be taken. In the above method, after the painted sheet is supplied between the molds, the painted sheet is preformed by vacuum forming along the cavity surface of the mold, and then the mold is clamped. The above effects can be obtained even with a larger molded product.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram conceptually explaining the present invention in one form. FIG. 2 is a conceptual view showing a state in which a "gas pool (pool)" is generated in the vicinity of a painting sheet in a conventional simultaneous injection molding painting method which does not use a gas escape portion as in the present invention. FIG. 3 is a cross-sectional view for explaining a defective portion of the injection resin derived from a gas pool in the resulting painted product.

First, as illustrated in FIG. 1E, in the simultaneous painting method for injection molding of the present invention, a mold A (in this case, a male mold) is used.
The final filling position, which is the position at which the resin P injected into the cavity formed by the mold B (in this case, the female mold) is filled with the resin P, is located at a position away from the painting sheet S. And injection molding. FIG. 1 (A)
FIG. 3 is a plan view showing a relationship between the outer shape of a certain painted molded article M and a gate G. 1 (B) to FIG. 1 (E)
FIG. 2 is a cross-sectional view taken along a line YY including a portion to be a final filling position of a resin with respect to the decorative molded product M of FIG. FIG. 1B shows a state in which the resin P in a flowing state starts to be injected into the cavity 1 from the gate G of the mold A after the pre-forming and the mold clamping of the painting sheet S. Shows how it enters the cavity. The injection mold is composed of a pair of molds A and B. When the pre-molding of the painted sheet is also used as the injection mold, the mold B is also used as a vacuum mold for pre-forming the painted sheet. Becomes The painted sheet S is already preformed and is in a state along the cavity surface of the mold B. In the case illustrated in FIG. 1, in the cavity 1 formed by the molds A and B, a position in the cavity away from the painting sheet S so as to invade toward a part on the mold A side that becomes a core mold. In addition, a final filling position of the resin to be the gas release section 2 is provided.

Then, the resin P gradually progresses from the gate G toward the periphery thereof, and from the state of FIG.
FIG. 1 shows a state in which the filling of the resin is completed through the state of FIG.
This is the state of (D). FIG. 1E is an enlarged cross-sectional view of a main part around the gas release portion 2 at the final filling position in FIG. As can be seen from FIG. 1 (E), in the present invention, the gas occupying the cavity as the resin is filled finally accumulates in the gas escape portion 2 and the resin P is not filled. A partial gas pool 3 is formed. As described above, in the present invention, the gas reservoir 3 is a part remote from the painted sheet (in FIG. 1 (E), the side opposite to the painted sheet of the molded product), and therefore, the part is a painting surface of the painted sheet. However, no product defect due to poor painting occurs. In addition, an air vent communicating with the outside of the mold is provided in the gas escape part 2 (not shown). If the gas can be completely and completely escaped from the air vent to the outside of the mold at all times, the gas trap 3 is formed in the gas escape part 2. Does not occur. In the present invention,
A gas escape portion may be provided to prevent gas accumulation, but this requires measures such as slowing down the injection speed of the resin, and the injection conditions are narrowed. Therefore, by providing a gas escape portion as described above, even if a gas pool occurs,
It is good to avoid product defects.

On the other hand, if simultaneous injection molding and painting are performed without providing a gas escape portion as in the present invention, the result is as shown in FIG. 2 and FIG. As shown in FIG. 2, the gas reservoir 3 is a sheet S with a picture.
It occurs at the position in contact with. As a result, as shown in FIG. 3, in the obtained painted molded article M, a defective portion 4 is generated in a part of the injected and solidified resin P at a position in contact with the painted sheet. For this reason, in the case of the laminated sheet in which the painted sheet is laminated on the molded product and integrated with the molded product, the painted sheet S is not in close contact with the molded resin P, resulting in poor adhesion. In addition, when the painting sheet is a transfer sheet, the transfer layer that transfers to the molded product is not in close contact with the resin P at the defective portion 4, resulting in poor adhesion. As a result, poor painting results.

The size (volume) of the gas release section 2
The size (volume) of the gas reservoir may be such that even if a gas reservoir is generated, the portion does not come into contact with the painting sheet. In FIG. 1 which is a conceptual diagram, the gas escape part 2 is exaggerated relative to the shape of the painted product and is drawn relatively large for easy understanding. However, as long as the gas escape portion does not interfere with the shape of the molded product, the size of the gas escape portion as shown in FIG. 1 may be used. In addition, although the gas escape portion becomes a convex portion in the obtained painted product, after the molding, a part or all of the convex portion may be trimmed (cut off).

[0015] Usually, the gas release portion is located at the final filling position when the gas release portion is not provided.
Usually, it may be provided on an extension in the direction in which the resin is filled. Normally, as shown in FIG. 1, the gas release portion is provided on the male side near the parting line where both the male and female types are in contact, where gas easily accumulates. Therefore, when the gate G is located at the center of the elliptical painted product M shown in FIG. 1 (A), the gas escape portion is in the long axis direction of the ellipse.
Since the outer peripheral portion that intersects with the Y line is the final filling position, it is sufficient to provide it at that portion. In other words, it is only necessary to provide a gas relief portion in a part of the entire outer periphery.However, from the point of design, function, strength, etc. of the shape of the molded product, a convex portion having the same cross-sectional shape as the gas release portion is required. It may be provided on the entire outer periphery. That is,
In this case, the sectional view of FIG. 1B to FIG. 1D or FIG. 1E is also a sectional view of the decorating molded product M shown in FIG. Conversely, even if the cross-sectional shape is as shown in FIG. 1 (B), if the convex portion of the cavity serving as the gas release portion 2 is not located at the final filling position of the resin, the convex portion may have the convex shape. The part does not have any effect as a gas release part intended in the present invention.

In the case of the shape of the painted molded article illustrated in FIG. 1, the gas escape portion is the outer peripheral portion of the molded product, but of course, depending on the shape of the molded product, the gas escape portion is the outer peripheral portion. Not necessarily. In the embodiment illustrated in FIG.
The gas escape part was provided so that the cavity was extended to the mold A side, which is the core mold. However, the gas escape part was marked with the final filling position of the resin with respect to the cavity obtained by clamping the male and female molds. It is sufficient to provide the portion in contact with the sheet, and the position where the gas escape portion is provided is not limited to the mold on the core side. In addition, a mold divided into a plurality of parts may be used for the female mold, the male mold, and the like. Further, as can be understood from the above description, the gas escape portion is for allowing gas to escape and accumulate in that portion, not for allowing gas to always escape outside the mold. However, of course, the gas may escape from the gas escape portion to the outside of the mold.

The form for simultaneous injection molding and painting used in the present invention is not particularly limited in the form of gate (for example, pin gate, film gate, side gate, submarine gate (tunnel gate), etc.), position and number. It may be appropriately selected according to the shape of the molded product, the shape of the painted surface, the injection conditions, and the like, and is arbitrary. In short, the final filling position of the resin is
The relationship between the shape of the cavity and the gate may be such that the gas escapes away from the picture sheet. Also, the material of the mold is not particularly limited, and for example, S50C, S55C, S55C
As a mold material such as CM3 and SCM4, besides various conventionally known steel materials, other metals and metal alloys such as copper, and nonmetal materials such as ceramics and the like may be used.

The simultaneous injection molding simultaneous painting method of the present invention is characterized in that injection molding is performed using the above-described gas release portion, and the other portions are applied with various techniques in the conventionally known simultaneous injection molding simultaneous painting method. You can do it. Therefore, as one mode of the simultaneous injection molding painting method of the present invention,
An example of continuous production using a continuous strip on a painted sheet,
A description will be given of the order of supply of the painted sheet, heat softening, preliminary molding, and injection molding, with reference to the conceptual diagrams of FIGS. Although FIGS. 4 to 7 have been referred to in the description of the prior art, in the present invention, the same drawings are referred to because the gas release unit 2 is the same as in the prior art. It is needless to say that the painted sheet used in the present invention may be either a single sheet or a continuous strip. As described above, the illustration of the gate of the mold A, the air vent, the ventilation hole of the mold B, the vacuum source, and the like are omitted. In these figures, hatched hatching indicates a virtual cut surface.

First, FIG. 4 shows a state before the supply of the painting sheet. The type A is a male type and is a fixed type to be attached to a fixed side die plate. The mold B is a female type and is a movable type to be attached to the movable side die plate. A gate is provided on the cavity surface of the mold A. Of course, when a large number of molded articles are taken by one mold, a gate is provided in a cavity for each molded article. On the other hand, on the cavity surface of the mold B, there are provided ventilation holes formed of holes and grooves for preforming the painting sheet.
The vacuum hole is connected to an external vacuum source, and an evacuation is appropriately performed by an on-off valve. FIG. 4 shows a state where the leading end of the continuous belt-shaped sheet S unwound from the roll R is gripped by the transport chuck 21 from the front and back.

Next, from the state shown in FIG. 4, the painted sheet S is transported between the pair of dies A and B in the opened state.
The state after the supply of the painting sheet in FIG. 5 is supplied. That is, the transport chuck 21 that reciprocates up and down by an AC servomotor or the like moves downward while holding the pictorial sheet S, and moves to a position where the receiving chuck 22 located below the outside of the mold B can grip the leading end of the pictorial sheet. , To convey the picture sheet. Receiving chuck 2 driven by a fluid pressure cylinder or the like
2 completes the gripping of the tip of the painting sheet, the transport chuck 21 releases the gripping of the painting sheet, moves upward outside the mold and returns to the original position, and moves the painting sheet upstream of the mold B in preparation for the next shot. Grip on the side. Next, the clamp 23 always located between the molds moves forward to the mold B side (to the left in the drawing), and presses and fixes the painting sheet against the parting surface of the mold B. As a result, the supply of the painting sheet between the molds is completed. The clamp 23 is a frame having a substantially rectangular shape as viewed from the parting surface, and presses and fixes the painting sheet S against the parting surface of the mold B so as to surround four sides of the cavity of the mold B. The clamp 23 has sliding rods (not shown) connected to its four corners slidably fitted into the mold B, and the sliding rod is moved forward and backward with respect to the parting surface of the mold B by a fluid pressure cylinder or the like. This releases / fixes the painted sheet.

When performing vacuum forming (preliminary molding) of the painted sheet using an injection mold, first, a heating plate 24 for heating and softening the painted sheet is moved from a retracted position (not shown in FIG. 4) outside the mold. It moves between the molds and moves to a position facing the painted sheet to be heated. This state is shown in FIG. In addition,
The pre-molding of the painted sheet may be performed using an external mold different from the injection mold, and then the molded painted sheet may be supplied between the molds. In this case, the hot plate can be omitted. Further, the heated painted sheet may be supplied between the molds after the painted sheet is heated with a hot plate outside the mold.

Next, as shown in FIG. 6, first, heating and softening of the painted sheet S is performed. The hot platen 24 moves forward (to the left in the drawing) and moves to a position where it contacts the clamp 23. The heating surface of the hot platen is radiantly heated in a non-contact manner with a predetermined distance from the heating surface of the hot platen. In addition, at the same time when the hot platen moves to the heating position, in the same figure, a heating line such as a nichrome wire or a cutter 25 made of a cutting tool or the like which extends over the hot platen comes into contact with the painted sheet, and cuts the painted sheet. Then, the sheet portion to be used in the current shot is separated from the upstream side to be used in the next and subsequent shots. In the case of a heating filament, the cutting is performed by heating and melting. A receiving groove 26 is formed on the parting surface of the mold B so as not to disturb the cutter.
5 is provided on a surface portion facing the same. For the purpose of heating and softening the painted sheet, as shown in FIG. 6, in addition to a non-contact type hot plate which heats the painted sheet by radiant heat without contact with the painted sheet, a contact which heats the painted sheet by conductive heat. Sometimes a hot plate is used.

After the heating and softening of the painted sheet is completed or after a certain period of time after the start of the heating and softening, air is sucked in from a ventilation hole (not shown) provided in the mold B, and the painted sheet is vacuum-formed to form the mold B. The prepainted sheet is formed along the cavity surface 27 (see FIG. 6). The term “vacuum forming” as used in the present invention includes vacuum / pressure forming in addition to vacuum forming.

If a hot plate for heating and softening the painted sheet is inserted between the molds after the preforming, the hot plate 24 is moved and retracted from between the two molds to a retracted position outside the mold. Then, both molds A and B are clamped. FIG. 7 shows a state of the prepainted sheet after pre-forming and mold clamping. In addition, as shown in FIG.
In the parting surface of the mold A, a receiving groove 2 serving as a concave portion capable of housing the clamp so that the clamp 23 does not disturb the mold clamping.
8 is provided on a surface portion facing the clamp. Usually, a runner and a gate (not shown) communicating with the injection nozzle are provided on the side of the mold A, through which the resin in a flowing state is injected into a cavity formed by both the molds and injected. Then, the resin that is in a fluidized state is injected and filled into the cavity formed by both molds by heating and melting, etc., and after the resin is solidified by cooling etc., the mold is opened. Is obtained. In the case of a transfer sheet, only the base sheet is peeled off from the molded product. In the case of a laminated sheet, an excess of the painted sheet that protrudes to the outside of the painted molded article is trimmed (cut).

[Painting sheet] The painting sheet which can be used in the simultaneous injection molding simultaneous painting method of the present invention using the injection molding simultaneous painting mold as described above may be a conventionally known painting sheet as a transfer type or a laminate type. And is not particularly limited. The 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 transfer type,
The adhesive layer may be omitted in both the laminate type.

(Base Sheet) As the base sheet, a resin sheet having moldability is typically used. Examples of the resin sheet include olefin resins such as polyethylene, polypropylene and olefin thermoplastic elastomers, polyester resins such as polybutylene terephthalate, ethylene terephthalate isophthalate copolymer, vinyl chloride resin, acrylic resin, ABS (acrylonitrile- A single layer of a sheet of a thermoplastic resin such as a butadiene-styrene copolymer) resin, a polyamide resin, or another thermoplastic elastomer such as a urethane-based resin, 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 process for making the base sheet colored transparent or colored opaque, or colorless opaque 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.

(Decoration layer) The decoration layer is formed by a conventionally known method such as gravure printing, silk screen printing, offset printing, a pattern layer on which a pattern or the like is printed with a material, a metal such as aluminum or chromium by a known vapor deposition method or the like. It is a metal thin film layer formed on a part or the whole surface. 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. Chlorinated polyethylene, chlorinated polyolefins such as chlorinated polypropylene,
Polyester resin, urethane resin, acrylic resin, vinyl acetate resin, vinyl chloride-vinyl acetate copolymer, thermoplastic resin such as cellulose resin, urethane resin, thermosetting resin such as epoxy resin, etc. Used as a mixture. 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

(Adhesive layer) On the back side of the painted sheet, an adhesive layer such as a corona discharge treatment, a known various primer coating or the like, or a heat-sensitive adhesive layer is applied in order to improve the adhesiveness with the molding resin. Sometimes. Known resins such as a thermoplastic resin and a thermosetting resin are used for the adhesive layer. Specific examples of the resin include, for example, a styrene resin such as polystyrene and poly α-methylstyrene or a styrene copolymer, poly (meth)
Acrylic resins such as methyl acrylate, poly (meth) acrylate, and poly (butyl methacrylate); vinyl polymers such as polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, and polyvinyl butyral; Rubber resins such as isoprene rubber, polyisobutyl rubber, styrene butadiene rubber, butadiene acrylonitrile rubber, coumarone resin, vinyl toluene resin, polyamide resin, polychlorinated olefins, etc., natural or synthetic resins,
One or a mixture of two or more of various ionomers is used. In addition, in the painted sheet on which the adhesive layer is formed,
When the adhesive layer comes into contact with the molding resin at the time of injection, a gas due to volatilization of the residual solvent in the adhesive layer is more likely to be generated. However, in the present invention, even in such a case, the gas escape portion is effective because product defects such as poor adhesion of the painted sheet and poor transfer of the transfer layer can be prevented.

[Molding resin] The molding resin to be injection-molded is not particularly limited as long as it is a known resin in a conventionally known injection molding simultaneous painting method. For example,
If it is a thermoplastic resin, a polyolefin resin such as polyethylene or polypropylene, a vinyl chloride resin, an acrylic resin, an ABS (acrylonitrile-butadiene-styrene copolymer) resin, a styrene resin, an AS (acrylonitrile-styrene copolymer) resin, polycarbonate There are resins and the like, and as the curable resin, there are an unsaturated polyester resin, a curable acrylic resin, a two-part curable urethane resin, an epoxy resin and the like. The thermoplastic resin is injected in a fluidized state by heating and melting, and the thermosetting resin is injected in a fluidized state by appropriately heating the uncured material. Above all, in the present invention, it is possible to prevent the occurrence of product defects due to poor painting due to poor adhesion of the painted sheet or poor transfer of the transfer layer due to gas pools, so that the flow of the injection resin is quick and gas easily accumulates. It is particularly effective in the case of a resin, for example, 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 include an ink layer formed by printing or the like, a metal thin film formed by vacuum evaporation or the like, and examples of invisible patterns include colorless and transparent to visible light. For example, a pattern printed with a fluorescent ink that emits fluorescence by ultraviolet irradiation is used. Further, in the present invention, regarding the heating softening and preforming of the painted sheet, if the sheet is sufficiently formed to follow the shape of the mold without performing these steps (generally, when the drawing is shallow),
These can be omitted.

[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 product was a substantially rectangular panel having a width of 40 mm and a length of 400 mm as a panel for vehicle interior, and the cross section of the front side serving as the painted surface was substantially trapezoidal. A) was prepared, and a mold capable of taking two of them was prepared. The gate was provided at one point in each cavity of each molded product, and at the center of the molded product. As shown in FIG. 1E, one of the two cavities on the mold is formed as a gas escape portion only at the four corners of the rectangle of the outer periphery of the molded product as shown in FIG. The back side of the product was shaped to be a protrusion protruding 5 mm away from the painted sheet. The other one had a shape in which the outer periphery of the molded product was in contact with the painted sheet without providing a gas escape portion as shown in FIG. 2 as a comparative example.

On the other hand, as for the sheet with a picture, the surface of the acrylic resin film having a thickness of 125 μm, which is on the back side (molding resin side), is mainly composed of a binder based on a mixture of acrylic resin and vinyl chloride-vinyl acetate copolymer. A sheet was prepared by printing a wood pattern with an ink to which a pigment was added and applying a 2 μm-thick adhesive layer made of a chlorinated polypropylene resin. Polypropylene resin was used as the molding resin.

Then, injection molding was performed according to the procedure as illustrated in FIGS. First, the sheet S with a picture was conveyed on the parting surface of the female die B by the conveying chuck 21 and the receiving chuck 22, and then fixed to the parting surface by the clamp 23 (FIG. 5). Next, the hot platen 24 is inserted between the two molds from the retracted position, heating of the painted sheet is started by radiant heat in a non-contact manner, and thereafter, the softened painted sheet is evacuated from the female mold, and the softened painted sheet is placed on the cavity surface of the female mold. According to No. 27, the prepainted sheet was formed by vacuum forming. Thereafter, the hot platen 24 was retracted to a retracted position outside the mold, and then both molds were clamped (FIG. 7). Then, the heated and melted polypropylene resin is injected into the cavity formed by both molds, and after the resin cools and solidifies, the mold is opened, the molded product is released, and the excess painted sheet that protrudes to the periphery of the molded product is trimmed. Thus, a painted molded product in which the painted sheets were laminated was obtained.

In the embodiment in which the gas escape portion was provided, the obtained molded product did not generate gas pools at the four corners of the outer peripheral portion in contact with the painted sheet. The molded article adhered to the molding resin to the end of the part, and the painted sheet was not lifted up at the end, and a molded article with good painting was obtained. However, in the comparative example in which the gas escape portion was not provided, gas pockets were generated in contact with the painted sheet at the four corners of the outer peripheral portion, so that a defective portion was formed in the molding resin, and the painted sheet was formed at that portion. It came up without adhering to the resin.

[0036]

According to the present invention, even if a gas pool is generated at the final filling position, that portion is away from the painted sheet. The sheet does not adhere to the molding resin, and as a result, poor painting such as poor adhesion of the painted sheet (in the case of a laminated sheet), poor adhesion of the transfer layer (in the case of a transfer sheet), etc. No product defects occur. In addition, since the portion where gas accumulation occurs is a portion that does not affect the painted surface, the injection molding conditions can be widened.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram conceptually illustrating a simultaneous injection molding painting method of the present invention.

FIG. 2 is a cross-sectional view conceptually illustrating a gas pool generated in the case of the conventional simultaneous injection molding painting method.

FIG. 3 is a cross-sectional view conceptually illustrating a defect in the painted molded product obtained in FIG. 2;

FIG. 4 is a conceptual explanatory view of a procedure according to an example of a simultaneous painting method for injection molding (part 1: before supplying a painting sheet).

FIG. 5 is a conceptual explanatory view of a procedure (part 2: after supplying a sheet with a picture).

FIG. 6 is a conceptual explanatory view of the procedure (part 3: painting sheet heating and softening).

FIG. 7 is a conceptual explanatory view of the procedure (part 4: vacuum forming of a sheet with a picture, after clamping).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cavity 2 Gas escape part (final filling position) 3 Gas reservoir 4 Defect part 21 Conveying chuck 22 Receiving chuck 23 Clamp (frame) 24 Heating plate 25 Cutter 26 Receiving groove 27 Cavity surface 28 Receiving groove A type (fixed type, male) Type) B type (movable type, female type) G Gate P Resin R Roll S Painting sheet

Claims (2)

[Claims] 1. After supplying a painted sheet between a pair of molds in a mold open state, the molds are clamped, and a resin in a flowing state is injected into a cavity formed by the molds, and simultaneously with molding. In the simultaneous injection molding painting method in which the surface of a molded article is painted with a painted sheet, the final filling position of the resin when the resin injected from the gate is filled into the cavity to be one molded article is determined from the painted sheet. Injection molding simultaneous painting method, wherein a gas escape portion is provided at the distant position in the cavity so as to be located at a distant position. 2. The simultaneous painting method for injection molding according to claim 1, wherein after the painting sheet is supplied between the molds, the painting sheet is preformed by vacuum forming along the cavity surface of the mold and then clamped. .