JPH0957833A - Laminated blow molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a laminated molded article having a metallic gloss by a method wherein molds are closed under the condition that a transparent resin sheet, onto the rear surface of which a metal foil is pasted and, at the same time, on the front surface of which a large number of fine through holes are bored, is pinched between the cavity surface of the mold and the surface of a parison and finally the air is blown in the parison. SOLUTION: A roll 20, to which a transparent resin sheet S having a metal foil pasted onto its rear surface is wound up, is arranged through a roll stand 22 at the position hanging downwards along the surface of a parison P hangingly discharged from a die head 2 above molds 8. The molds 8 are closed under the condition that the transparent resin sheet S, on the front surface of which a plurality of fine through holes are arranged and the front surface of which is opposite to the cavity surface of the mold, is pinched between the cavity surface of the mold and the surface of the parison P and finally the air is blown into the parison and, at the same time, the mold 8 is heated up to a temperature which exceed the softening temperature of the surface of the resin sheet S. After that, the temperature of a molded article is lowered to a temperature enough to unload the molded article.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding blow molding method for molding a molded article in which a resin sheet is bonded to the surface of a parison, and particularly to a high surface area using a transparent resin sheet having a metal foil lined on the back surface. The present invention relates to a laminating blow molding method capable of obtaining a resin sheet laminating molded product having the properties and metallic luster.

[0002]

2. Description of the Related Art In blow molding for producing a hollow resin product from a parison injected or extruded into a cylindrical shape from a die head, a parison is injected or extruded from a die head, and a pre-blow is applied to a parison formed into a bag by a parison pinch. Line, inflate it slightly, put it in an open mold, close the mold, evacuate the gas in the cavity formed by the mold and the parison, and then vacuum pump the device through a small air vent hole to the mold surface Then, high-pressure air is blown into the parison to form the parison into a predetermined shape based on the cavity, and the parison is cooled with a mold to complete the molding. In this way, the molded resin product is opened and taken out. FIG. 6 shows a conventional blow molding machine. 6 shows a so-called side-feed type blow molding machine 1 in which molten resin is supplied from one side of the die head 2, and the high-temperature molten resin pressed by the injection device 4 is the resin supply port 2a. And passes through an annular passage provided between the die head 2 and the mandrel 3 and is discharged from the annular space passage 7 at the lowermost end to form a parison P. A passage 2b and a valve 5 (or plug) provided outside the passage 2b are disposed at a position 180 ° away from the resin supply port 2a of the die head 2. The core 3a is connected to the paricon rod 6a penetrating the mandrel 3 and is slightly moved up and down in the vertical direction by the operation of the paricon cylinder 6 to control the wall thickness of the parison P (gap). ) Can be adjusted.

On the other hand, a transparent resin sheet S is interposed between the parison P discharged from the blow molding machine 1 and the mold cavity, and the mold is clamped, as shown in FIG. It has been conventionally practiced to produce a blow-molded product in which the transparent resin sheet S is attached to the surface.

[0004]

However, such a conventional laminated blow-molded product has insufficient surface properties and gloss even if the sheet S is made of a transparent resin. Even if an attempt is made to obtain a molded article having a metallic luster using a sheet S having the metal foil attached / detached on the back surface, there is a problem that the predetermined purpose cannot be obtained because the gloss of the bonded molded article is insufficient. .

The present invention has been made in view of the above problems, and an object of the present invention relates to a bonding blow molding method for easily obtaining a bonded molded product having a metallic luster.

[0006]

In order to achieve the above object, in the first aspect of the present invention, a resin sheet is attached to the outer surface of a parison ejected from a die and sandwiched by a pair of left and right molds. A bonding blow molding method for producing a hollow molded product, wherein a transparent resin is used for the resin sheet, a metal foil is adhered to the back surface of the resin sheet, and a large number of fine particles formed by punching are formed on the surface. After forming the through-hole, face the mold cavity surface and sandwich it between the mold cavity surface and the parison surface to close the mold and blow the mold at the same time as the surface of the resin sheet. Is heated until it exceeds the softening temperature, and then the molded product is taken out after being cooled to a temperature sufficient for taking out the molded product. In the second invention, a resin sheet in which a metal foil is sandwiched between transparent resin sheets is used, the resin sheet is made to face one mold cavity surface, and is sandwiched between the mold cavity surface and the parison surface. The mold is closed with, and at the same time as blowing is performed, the mold is heated until it exceeds the temperature at which the surface of the resin sheet softens, and then the molded product is taken out after cooling to a temperature sufficient to take out the molded product. I chose

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a transparent resin having a fine through hole formed by punching the metal foil on the back surface between the discharged parison surface and the metal cavity surface. While the sheet is positioned in the stretched state, the drooping parison and the transparent resin sheet are closed at the same time between the molds, and the resin sheet is blown onto the mold cavity surface heated near the softening temperature of the resin through the parison. When pressed, the surface of the resin sheet is softened and melted, and a bonded blow-molded product having a metallic luster and good surface transferability can be obtained. Then, when the resin sheet is preliminarily heated to a temperature close to the softening temperature and then bonded and clamped, the adhesion between the parison and the resin sheet is further improved.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 5 relate to an embodiment of the present invention, FIG. 1 is an overall vertical cross-sectional view of a blow molding machine, FIG. 2 is a perspective view of the blow molding machine, and FIG. 3 is a metal foil attached to the back surface of a transparent resin sheet. FIG. 4 is a partial cross-sectional view of a blow-molded product when a resin sheet in which a metal foil is sandwiched between transparent resin sheets is used.
FIG. 5 is a graph for explaining the mold temperature change.

In FIGS. 1 and 2, a pair of left and right molds 8, 8 are disposed below the die head 2 of the blow molding machine 1 so that they can come in contact with and separate from each other. The roll 20 having the transparent resin sheet S having the metal foil 40 adhered on the back surface thereof is wound at a position where the parison P discharged from the head 2 and hung downward is suspended from the roll base 2
It is arranged via 2. A roll base 22 is attached to the lower end of the roll 20, and a cutter 30 whose tip is formed by a sharp blade that horizontally moves back and forth in the parison direction by the operation of an air cylinder 30a is arranged in front of the cutter 30. Cutter seat 3 having a groove into which the cutting edge of the cutter 30 is fitted
0b is provided, and the suspended transparent resin sheet S can be cut at any time without damaging the surface of the parison P. Further, a sheet clip 24 for holding the lower end of the transparent resin sheet S and holding the transparent resin sheet S in a vertically extended state during operation is provided at the lower end of the mold 8.

On the other hand, in the portion of the mold 8 facing the cavity surface, a heating medium or a cooling medium is switched and flowed if necessary,
Medium passage 8 for heating or cooling the cavity surface of the mold 8.
a (not shown) in which a is disposed (heat medium or refrigerant body)
It is connected to the switching supply device. Further, a plurality of vent holes 8b which penetrate the mold 8 from the cavity surface of the mold 8 at right angles to the cavity surface and discharge air are provided at appropriate intervals. Further, in order to positively suck the air discharged from these vent holes 8b, a collecting duct 10 is provided so as to cover the outside of the mold 8, and an exhaust pipe provided with a solenoid valve 12 and a suction fan 14 is provided. 11 are provided. Alternatively, the mold 8 may be made of a metal provided with countless fine air holes, that is, a porous metal, instead of the vent hole 8b.

A transparent resin sheet S wound around a roll 20
Can be made of the same resin as the parison P, or can be made of a resin different from the parison P. The metal foil 40 was attached to the back surface (the side of the parison P) of the transparent resin sheet S (FIG. 3).
Alternatively, the metal foil 40 may be sandwiched between the sheets S (FIG. 4).

The thickness of the transparent resin sheet S is not preferably too thick because it is necessary to manufacture a laminated blow-molded product, and is usually 1 mm or less, preferably 0.5 mm.
The following thin ones are desirable. If the transparent resin sheet S is too thick, it is difficult to obtain a molded product that conforms to the cavity shape in the deep shape in which wrinkles easily occur. In addition, the cooling time after molding becomes long and the productivity is lowered. Further, if it is too thin, the transparent resin sheet S may be damaged during molding. As shown in FIG. 2, on the surface of the transparent resin sheet S, fine through holes h for discharging the air present between the parison P and the resin sheet S at the time of press-molding with the parison P are provided, as shown in FIG.
A plurality of them are arranged in a lattice or zigzag pattern.

The diameter of the fine through hole h is 0.1 mm to 1 mm.
It is preferable that the arrangement density is 0.1 mm or more and 0.3 mm or less, and the arrangement density is at least 1 per 100 cm ^2, but preferably 4 or more per 100 cm ^2.
It is desirable that the number is 00 or less.

Blow pressure of blowing after closing the mold
Is the surface of the parison P and the transparent resin surface to be attached to it.
Completely eliminates the air between the S
To prevent defects such as the formation of bubbles on the surface of the molded product.
For at least 4 kgf / cm ²Pressure.

The heating temperature and the cooling temperature of the mold 8 are appropriately selected according to the kind of resin on the surface of the transparent resin sheet S which is in contact with the mold. That is, the transparent resin sheet S is usually produced by extrusion molding and has a poor surface property. In order to improve the surface property of the bonded blow-molded product of the present invention, in other words, the surface transferability of the molded product is improved. In order to achieve this, the resin is heated to a temperature at which it softens or higher, and after surface transfer is sufficiently performed, it is cooled immediately. In addition, in order for the parison resin to appear on the surface of the molded product, it is necessary to heat the parison resin to a temperature at which the parison resin softens. The softening temperature of the resin is equal to the glass transition temperature in the case of the amorphous resin, and is 110 ° C to 130 ° C in the case of the ABS resin.

On the other hand, in the case of a crystalline resin, the temperature between the crystallization temperature and the melting point is suitable, 130 ° C. to 160 ° C. for PP and 100 ° C. to 1 ° C. for PE.
The temperature is 30 ° C and 180 ° C to 230 ° C for nylon 6. On the other hand, the cooling temperature is set to about 80 ° C. to 100 ° C., and the temperature change of the mold temperature during one step is, for example, as shown in FIG. 4, two methods of changing the temperature curve A and the temperature curve B. , And either may be used. Temperature curve A
Is called the "cool start" method in which the mold temperature is low when the parison P is injected and the mold is closed, and the temperature curve B is called the "hot start" method in which the mold temperature is high when the mold is closed. Various types of oil, water, and pressurized water (steam) can be used as the heat carrier and refrigerant.
Is preferably used, and it is desirable to use the same substance at different temperatures. In addition to the case of heating and cooling the die 8 as described above, a method of directly heating the surface of the parison P from the outside with a light source or a heat source can also be adopted.

An adhesive may be applied in advance to the surface of the transparent resin sheet S on the side contacting the parison, or
Alternatively, it is desirable to spray the adhesive solution in the form of spray or apply it with a brush so as to facilitate the bonding with the surface of the parison P at the time of molding.

As the material of the transparent resin sheet S,
EVA, PS, ABS resin, methacrylic resin, polyvinyl chloride, polycarbonate, PET, PBT, vinylidene chloride, ionomer, polyvinyl alcohol, PE,
PP, ethylene-based copolymer, etc. are used.

Further, as the metal foil 40 attached to the back surface of the transparent resin sheet S, aluminum, copper, brass, zinc, etc. are considered, but other than these metal foils 40 may be used.

These metal foils 40 are attached to the transparent resin sheet S by, for example, vapor deposition, adhesion, spraying or the like. In this case, if the metal foil 40 has a large film thickness, wrinkles are likely to occur during molding.

The operation of the blow molding method of the present invention in the blow molding machine 1 configured as described above will be described.

First, while the molds 8 and 8 are held in the mold open state, the transparent resin sheet S having the metal foil 40 adhered on the back surface is wound down from the roll 20 and hung down, and the lower end is pinched by the sheet clip 24. , Keep it stretched up and down. And
The parison P is discharged from the lower end of the die head 2 with an injection device or the like. During this time, the molds 8 and 8 are started to be heated according to one of the temperature curves A and B shown in FIG.

Next, the mold is closed and the upper end of the resin sheet S is cut by the cutter 3.
Cut horizontally at 0, and put the transparent resin sheet S on the parison P surface.
It is molded in the state of being stuck together. On the cavity surfaces of the molds 8 and 8, the temperature is in the vicinity of the softening point of the transparent resin sheet S, the surface of the transparent resin sheet S is softened and melted, and the mold cavity surface is pressed and transferred to the mold cavity surface. At the same time, the surface of the parison and the surface of the resin are pressed and integrated by the pressurized air blown into the parison P via the blow pins, and are joined together.

Since the molded product obtained by the lamination blow molding of this embodiment has particularly excellent gloss, the metallic gloss can be further emphasized by the metal foil 40 sandwiched between the back surface of the transparent resin sheet S or the sandwich. Of.

As applications of such molded articles, for example, automobile bumpers, wheel covers, side moldings, grills, room mirrors, door mirrors, motorcycle exteriors, mud splashes, mirror stands, blackboards including magnet type, etc. can be considered. It may be applied to other molded articles other than these.

In addition to the above-mentioned molded products, for example,
By connecting an electric wire to the floor panel that can be heated or the metal foil 40, it can be expanded to the use of automobile-related parts such as a spoiler with a built-in antenna, a glove box door, and interior parts.

According to the method of the present invention, since the mold is heated at the time of closing the mold for blow molding, the transparent resin sheet S is heated and softened to a semi-molten state, and the surface of the molded product having a high gloss is obtained. Can be obtained.

If the plurality of fine through holes h provided in the resin sheet S have a small diameter of 0.3 mm or less, after the air is exhausted by melting the sheet surface by heating the mold. Since it is automatically crushed by the surroundings and closed, there is no problem that many pores remain on the surface of the product and deteriorate the quality.

[0029]

As is apparent from the above description, the present invention uses a transparent resin sheet having a metal foil adhered or sandwiched between the back surface of the transparent resin sheet or between the sheets and the surface of the resin sheet. Is heated until it exceeds the softening temperature, the surface of the resin sheet is softened and the parison is closely adhered, so the resin sheet is not damaged.
Further, without leaving holes on the surface, it fits to the curved state of the inner surface of the mold cavity, and an excellent bonded blow-molded product with high gloss surface transferability and metallic luster can be obtained.

[Brief description of drawings]

FIG. 1 is an overall vertical sectional view of a blow molding machine.

FIG. 2 is a perspective view of a blow molding machine.

FIG. 3 is a partial cross-sectional view of a blow-molded product when a resin sheet in which a metal foil is attached to the back surface of a transparent resin sheet is used.

FIG. 4 is a partial cross-sectional view of a blow molded product using a resin sheet in which a metal foil is sandwiched between transparent resin sheets.

FIG. 5 is a graph illustrating changes in mold temperature.

FIG. 6 is an overall vertical sectional view of a conventional blow molding machine.

FIG. 7 is a partial cross-sectional view of a conventional bonded blow-molded product.

[Explanation of symbols]

 1 Blow Molding Machine 2 Die Head 2a Resin Supply Port 3 Mandrel 3a Core 4 Injection Device 5 Valve 6 Paricon Cylinder 6a Paricon Rod 7 Annular Space Passage 8 Mold 8a Medium Passage 8b Vent Hole 10 Collecting Duct 11 Exhaust Pipe 12 Solenoid Valve 14 Suction fan 20 Roll 22 Roll stand 24 Sheet clip 30 Cutter 30a Air cylinder 30b Cutter seat 40 Metal foil P Parison S Transparent resin sheet h Fine through hole

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Claims (2)

[Claims] 1. A bonding blow molding method in which a resin sheet is bonded to the outer surface of a parison ejected from a die and is sandwiched by a pair of left and right molds to form a hollow molded product, wherein the resin sheet is transparent. A resin is used and a metal foil is attached to the back surface of the resin sheet, and a large number of fine through-holes formed by punching are punched on the surface, and then faced to the mold cavity surface and then the mold cavity surface. And the parison surface, close the mold, and at the same time perform blowing, heat the mold until it exceeds the temperature at which the surface of the resin sheet softens, and then to a temperature sufficient to remove the molded product. A laminated blow molding method, wherein a molded product is taken out after cooling. 2. A resin sheet in which a metal foil is sandwiched between the transparent resin sheets according to claim 1, the resin sheet is opposed to one mold cavity surface, and the mold cavity surface and a parison are used. The mold is closed by sandwiching it between the surface and the surface, and at the same time when the mold is blown, the mold is heated until it exceeds the temperature at which the surface of the resin sheet softens, and then cooled to a temperature sufficient to take out the molded product. A bonded blow molding method, wherein a molded product is taken out later.