JPH0957829A - Lamination blow molding method - Google Patents

Abstract

(57) [Abstract] [Problem] Laminated blow molding capable of obtaining a smooth and high quality laminated blow molded product having no step between the resin sheet and the parison and having excellent surface transferability and no gas intervening. It provides a method. SOLUTION: This is a bonding blow molding method in which resin sheets S are bonded together, and the resin sheet S is curved so as to be convex toward the parison P in plan view, and the parison P and the mold cavity surface are formed. Between the mold cavity surface and the parison surface, the mold closing operation of both molds 8 is started, and the back surface of the resin sheet and the parison surface are started. The mold closing operation is temporarily stopped at a position where most of the contacting parts are in contact with each other, and a certain time until the resin sheet S and the parison P are completely fused is held, and then the mold closing operation is restarted to complete the mold closing, After blowing, it is cooled and the molded product is taken out.

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 in particular, it has an excellent appearance without gas inclusions between the resin sheet and the main resin. The present invention also relates to a bonding blow molding method capable of obtaining a high quality resin sheet bonded molded product.

[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. The thing shown in FIG. 7 shows the conventional blow molding machine. 7 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 resin sheet is interposed between the parison discharged from the blow molding machine 1 and the mold cavity, the mold is clamped, and the resin sheet is pasted on the surface. It has been practiced in the past to produce blow molded articles.

[0004]

However, in such a conventional bonded blow-molded product, the resin sheet is broken during the blow molding, or wrinkles are generated on the surface of the molded product, so that a smooth flat surface is not formed. There is a disadvantage that air is present between the resin sheet and the parison surface, and air remains on the surface of the molded article as air bubbles, and the resin sheet and the parison surface do not adhere to each other over the entire surface. Therefore,
A plurality of fine through holes are previously punched in the resin sheet to be bonded to the parison, and air is positively sucked from the inner surface of the mold after the mold is clamped. A method of exhausting intervening air to achieve close contact between the two is also conceivable, but in this case, the perforation of the fine through holes of the resin sheet is complicated and costly, and the fine through holes are formed on the surface of the molded product after molding. There was a new problem that the traces of pores remained and impaired the appearance. In addition, the surface properties of the resin sheet of the conventional laminated blow-molded product are poor, and there is a drawback that the product value is low due to lack of gloss. Further, when the resin sheet has a seam, there is a problem that a step is likely to be formed at the seam and a continuous flat surface cannot be obtained.

[0005]

In order to solve the above problems and obtain a high-quality bonded blow-molded article having a smooth gloss and excellent surface properties, the first aspect of the present invention is used.
In the invention, a hollow product is obtained by pasting a resin sheet on the outer surface of the parison discharged from the annular resin passage between the die head and the core attached to the lower end of the mandrel, and sandwiching it with a pair of left and right molds. A method for laminating and bonding blow molding, wherein a resin sheet is curved so as to be convex toward the parison in a plan view, and the resin sheet is hung between the parison and the cavity surface of the mold to stand still, The resin sheet is sandwiched between the cavity surface and the parison surface to start the mold closing operation of both molds, and the mold closing operation is temporarily stopped at the position where the back surface of the resin sheet and most of the parison surface are in contact with each other. After a certain period of time until the resin sheet and the parison are completely fused together, the mold closing operation is restarted to complete the mold closing, and after blowing, the molded product is taken out by cooling. It was. Further, in the second invention, a resin sheet is attached to the outer surface of the parison discharged from the annular resin passage between the die head and the core attached to the lower end of the mandrel, and the parison is sandwiched between a pair of left and right molds to form a hollow shape. This is a method of laminating blow molding to produce a product, in which the resin sheet is held by a suction plate that protrudes in the parison direction from the outer periphery of the mold and that has a buffer mechanism that is contractible with respect to the pressing force in the middle. Then, the resin is curved so as to be convex toward the parison in a plan view and hung down between the parison and the mold cavity surface to stand still, and then the resin is interposed between the mold cavity surface and the parison surface. The two molds were closed at a constant mold closing speed with the sheet sandwiched, the mold closing was completed, and after blowing, the molded product was taken out by cooling. According to a third aspect of the present invention, in the first or second aspect of the present invention, the mold surface before or after mold closing is higher than or equal to the higher softening point of the softening point temperatures of either the resin sheet or the parison. It was decided to take out the molded product after heating to, and cooling the mold to a temperature at which the molded product can be taken out during or after blowing. Further, in a fourth invention, in the first to third inventions, before the resin sheet is sandwiched between the mold cavity surface and the parison surface to close the mold, the resin sheet is previously attached to the resin sheet. It was preheated to a temperature lower than the softening point temperature of. And 5th invention WHEREIN: In the 1st invention-4th invention, the inorganic materials, such as a metal plate, a metal foil, glass, a ceramic material, and a stone material, respectively between the resin sheet back surface and a parison surface, or It was decided to mold with any of organic materials such as leather, paper, and wood, or a combination thereof.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a resin sheet is hung between a discharged parison surface and a mold cavity surface in a state of being bent so as to be convex toward the parison in a plan view. Then, the mold is closed and then blown to press the resin sheet and parison against the mold cavity surface, and the surface of the resin sheet is transferred to the mold cavity surface. A good laminated blow molded product can be obtained. Also,
By heating the mold cavity surface above the softening point temperature of either the resin sheet or parison resin and clamping the mold, a molded product with better 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. Further, molded products having various designs and designs can be obtained by freely selecting the color of the resin sheet or adopting a resin sheet on which a decorative pattern or a decorative pattern is printed in advance. In addition, between the back surface of the resin sheet and the front surface of the parison, an inorganic material such as a metal plate, a metal foil, glass, a ceramic material, or a stone material, or
By molding with any of organic materials such as leather, paper and wood, or a combination thereof, it is possible to obtain a further expanded product group.

[0007]

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 an enlarged plan view of an essential part of the blow molding machine, and FIG. 3 is a surface state of a bonded blow molding product. FIG. 4 is a graph for explaining the mold temperature change, and FIG. 5 is an enlarged cross-sectional view of the resin sheet before and after bonding. In FIG. 1 and FIG. 2, a pair of left and right molds 8, 8 is disposed below the die head 2 of the blow molding machine 1 so as to be freely contactable and separable, and the outer periphery of the mold 8 has a rectangular flat plate shape. A plurality of suction plates 32 for suction-holding the outer peripheral edge of the resin sheet S are provided in a projecting manner in the direction of the parison P via the cushioning mechanism 30, and the opposing directions of the suction plates 32 are as shown in FIG. Is bent in a curved shape so as to be convex toward the parison P. The suction plate 32 is made of a stretchable resin and has a dish shape. Air in the internal space is sucked by a suction pump through a conduit to suck an object that comes into contact with the suction plate in a vacuum state.

On the other hand, in the portion of the mold 8 facing the cavity surface, a heat medium or a coolant 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.

The rectangular flat resin sheet S is a parison P.
In addition to the same type of resin as described above, a different type of resin from the parison P can be used. The resin sheet S may be a multilayer resin sheet, a metal foil, paper, glass fiber or the like may be laminated between the sheets in a sandwich shape, or the sheet may be filled with an inorganic substance (glass fiber, inorganic mineral, etc.). . However, since the sheet material attached to the burr portion may be crushed and reused for the next molding shot, basically the same material as the parison P is desirable. The thickness of the resin sheet S is not preferably too thick because it is necessary to manufacture a bonded blow-molded product, and is usually 1 mm or less, but preferably 0.2 mm to 0.4 mm and thin. If the resin sheet S is too thick, it is difficult to obtain a molded product that matches 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 resin sheet S may be damaged during molding. On the surface of the resin sheet S, fine through holes h for discharging the air present between the parison P and the resin sheet S during pressure-bonding with the parison P are formed in a lattice pattern or a staggered pattern at appropriate intervals. Arrange a plurality of them.
The diameter of the fine through holes h is 0.1 mm to 1 mm, preferably about 0.1 mm or more to 0.3 mm or less, and the array density is at least one per 100 cm ² ,
It is preferable that the number is 4 or more and 500 or less per 100 cm ² . The reason is that if the diameter of the fine through holes h is 0.1 mm or less, it is difficult to discharge gas, and
This is because, if it is m or more, hole marks are likely to remain after molding, and
The lower limit of the array density (1 or more per 100 cm ² ) is determined from the minimum required gas discharge area, and the upper limit of the array density (500 or less per 100 cm ² ) is the gas discharge amount even if it is provided more than this. The effect comes from being the same. However, when the elongated ribbon-shaped resin sheet S is locally attached to the surface of the parison P, the fine through holes h may be omitted (the intervening air deviates from the left and right ends of the ribbon-shaped resin sheet S). Therefore, the fine through hole h is not required intentionally).

The blowing pressure of the blowing after closing the mold completely eliminates the air between the surface of the parison P and the resin sheet S attached to the parison P, and the air remains between the two to leave the surface of the molded product. To prevent defects such as bubble formation,
The pressure is at least 4 kgf / cm ² .

The heating temperature and the cooling temperature of the mold 8 are properly selected according to the kind of resin on the surface of the resin sheet S which is in contact with the mold. That is, the resin sheet S is usually manufactured by extrusion molding and has a poor surface property. In order to improve the surface property of the bonded blow-molded product in the present invention, in other words, the surface transferability of the molded product is improved. Therefore, the resin is heated to a temperature at which the resin softens or higher, and after the surface transfer is sufficiently performed, the resin is quickly cooled. 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 110 ° C in the case of the ABS resin.
~ 130 ° C, 120 ° C ~ 14 for modified PPO resin
It is about 0 ° C. On the other hand, in the case of a crystalline resin, the temperature between the crystallization temperature and the melting point is suitable,
In the case of, it is 130 ℃ -160 ℃, and in the case of PE, it is 100 ℃.
℃ -130 ℃, nylon 6 is 180 ℃ -230 ℃. 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 changed to a temperature curve A and a temperature curve B as shown in FIG.
There are various methods, and either method may be used. The 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 kinds of oil, water, and pressurized water (steam) are used as the heat medium and the coolant, and it is desirable to use the same substance having 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.

On the surface of the resin sheet S on which the parison comes into contact,
Allow the adhesive to be applied beforehand, or spray-apply an adhesive solution in the form of a spray, or
It is desirable to consider brushing so as to facilitate the bonding with the surface of the parison P 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 holding both molds 8 and 8 in the mold open state, the resin sheet S is vertically hung down and held in an extended state by suction of a plurality of suction plates 32 that are in contact with the outer periphery. 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 to room temperature or a temperature near the softening point temperature of the resin sheet S according to one of the temperature curves A and B shown in FIG. The gist of the present invention is that after the back surface of the resin sheet S and the front surface of the parison P are completely fused by the latent heat of the parison P,
It is intended to clamp the two that are integrated with each other with the molds 8 and blow, and press the mold cavity surface to transfer the mold cavity surface. Therefore, in the first invention, after the mold closing operation of the mold 8 is started, the convexly curved resin sheet S first comes into contact with the parison P from the central portion, and the mold is further moved. The contact area between the resin sheet S and the parison P expands as the mold closing operation of (1) proceeds, and when the majority of the resin sheet S and the parison P are united and fused, the mold closing operation is temporarily stopped. After the fusion of the two is almost completely completed, the interrupted mold closing operation is restarted and the molds 8 are completely clamped. After the mold is clamped and blown, the mold is opened after a certain cooling time, and the molded product is taken out to obtain a product. On the other hand, in the second aspect of the invention, instead of inserting an interruption stop time in the middle of the mold closing operation, the mold closing operation is made continuous and the mold is closed at a constant mold closing speed. Initially, the resin sheet S and the parison P come into contact with each other, and the latent heat of the parison P melts the back surface of the resin sheet S to fuse and integrate the two. ) 30 is pressed and contracted, so that time for fusion and integration is secured. Therefore, in the first invention, the buffer mechanism 30 is unnecessary,
It may be omitted. In the above-mentioned first invention and second invention,
In either case, the resin sheet S abuts in a state of being convex toward the parison P side in a plan view, and as the mold closing operation proceeds thereafter, the contact area between the two expands from the central part of the parison P to the peripheral parts on both sides. The air existing between the two parts is also expelled from the central part to the peripheral parts on both sides, and the parison surface and the resin surface are pressure-bonded integrally and bonded, so that no air remains between them. Therefore, the finished state of the molded product after laminating is smooth, and a high quality resin sheet laminated molded product having an excellent appearance without gas interposition can be achieved.

In the resin sheet S, when the fine through holes h have no "return" at the time of punching, as shown in FIG. 6, holes are formed on the surface of the molded product even after the bonding molding is performed. Traces remain, and there is a fear that it may damage the aesthetics. In order to improve this problem, in the present invention, the resin sheet S has, for example, fine through holes h punched by a punching method such as a pressing method. As a result, as shown in FIG. 5, a convex protrusion 60 is formed on one of the minute through holes h. When the surface on which the convex protrusions 60 are formed faces the mold surface and is then clamped by being interposed between the mold surface and the parison surface as described above, the convex shape of the fine through-hole h is formed. As a result of the projection 60 being pressed and crushed, the fine through holes are closed and the traces of the holes disappear.

The resin sheet S used in the laminated blow-molded product of the present invention may be a normal commercial product produced by extrusion molding, but one side (blow-molded product surface side) may have a decorative pattern or a decorative pattern. If, for example, an ABS extruded sheet on which a decorative pattern is printed is used, various panel-shaped molded products having high gloss and arbitrary colors and patterns can be obtained. Its applications include daily necessities (chairs, TV stands, bookshelves, cabinets, system kitchens, blackboards, sheds, desk tops, piling tops, furniture doors, side panels, bathtubs, mirror stands, etc.) Home appliances (refrigerator doors, dishwashers) Doors, washing machine doors, washing machine side panels, TVs, speaker boxes, computer housings, etc. Automotive products (spoilers, glove box doors, instrument panels, rear partial shelves, door trims, side garnishes, console boxes, road floors, bumpers, fenders) There are building materials (doors, wall materials, partition boards, partitions, etc.) and sundries, etc., such as trunk lids, motorcycle fenders, and outer panels.

Further, as shown in FIG. 3, by embedding a metal foil 40 or the like on the inner surface of the resin sheet S on the parison side,
By connecting electric wires to the floor panel that can be heated or the metal foil 40, the applications of automobile-related parts such as a spoiler with a built-in antenna, a glove box door, and interior parts will be expanded. Further, by combining known techniques such as insert and foam molding, the usage can be further expanded. According to the method of the present invention, since the mold is heated when the mold for blow molding is closed, the resin sheet S is heated and softened to a semi-molten state, and the surface of the molded product is as shown in FIG. As shown in FIG. 3, a smooth surface having no step can be formed without forming the step 50 unlike the pasted molded article of the conventional method.
In addition, a plurality of fine through holes h provided in the resin sheet S
Is a small diameter of 0.3 mm or less, it is automatically crushed from the surroundings and closed after air is exhausted by melting the sheet surface due to heating of the mold, so many pores are Although there is no problem of remaining on the surface and degrading the quality, as described above, it is desirable that the fine through-holes h be punched holes having the convex projections 60 so that the traces of holes disappear after bonding.

[0017]

As described above, in the present invention,
The resin sheet is curved so as to be convex toward the parison in a plan view, and is hung down between the parison and the mold cavity surface to stand still, and then between the mold cavity surface and the parison surface. The mold closing operation of both molds is started by sandwiching the resin sheet, and the mold closing operation is temporarily stopped at a position where the back surface of the resin sheet and most of the front surface of the parison are in contact with each other to completely complete the resin sheet and the parison. After holding a fixed time until fusion, the mold closing operation was restarted to complete the mold closing, and after blowing, the molded product was taken out by cooling. Even if it is not provided, the resin sheet and the parison are fused and integrated while being degassed, and the die is clamped after the fusion, so that even if the die shape is complicated, the fusion failure does not occur. Moreover, since the mold is clamped after the resin sheet and the parison have been fused and integrated, there is no wrinkle or flaw remaining in the molded product even if the blow pin is inserted through both. Furthermore, by freely selecting the color of the resin sheet, it is possible to easily, easily, and inexpensively produce a multicolor, multi-layer molded product without changing the color with a single-layer blow molding machine. Further, by adopting a resin sheet to which a decorative pattern and a decorative pattern are added, a variety of designs and designs can be enjoyed. In the method of the present invention, since the mold is heated and cooled during molding, the surface of the resin sheet in contact with the mold cavity surface is softened and remelted, and there is no step at the boundary between the resin sheet end and the parison surface. A bonded blow-molded product is obtained.

[Brief description of drawings]

FIG. 1 is an overall vertical sectional view of a blow molding machine according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view of an essential part of the blow molding machine according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a surface state of a bonded blow-molded product according to an example of the present invention.

FIG. 4 is a graph illustrating a mold temperature change in the blow molding method according to the embodiment of the present invention.

FIG. 5 is an enlarged cross-sectional view of a resin sheet before and after bonding in a blow molding method according to an example of the present invention.

FIG. 6 is an enlarged cross-sectional view of a resin sheet before and after bonding showing another embodiment of the blow molding method according to the embodiment of the present invention.

FIG. 7 is an overall vertical sectional view of a conventional blow molding machine.

FIG. 8 is a cross-sectional view showing a surface state of a conventional bonded blow-molded product.

[Explanation of symbols]

 1 Blow Molding Machine 2 Dice 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 30 Buffer mechanism (damper) 30a Compression coil spring 32 Adsorption board 40 Metal foil 50 Step 60 Protruding protrusion P Parison S Resin sheet h Micro through hole

Claims (5)

[Claims] 1. A hollow product is obtained by attaching a resin sheet to the outer surface of a parison discharged from an annular resin passage between a die head and a core attached to the lower end of a mandrel, and sandwiching the resin sheet with a pair of left and right dies. A method for laminating and bonding blow molding, wherein a resin sheet is curved so as to be convex toward the parison in a plan view, and the resin sheet is hung between the parison and the cavity surface of the mold to stand still, The resin sheet is sandwiched between the cavity surface and the parison surface to start the mold closing operation of both molds, and the mold closing operation is temporarily stopped at the position where the back surface of the resin sheet and most of the parison surface are in contact with each other. Holding a certain time until the resin sheet and the parison are completely fused, the mold closing operation is restarted to complete the mold closing, and after blowing, the molded product is taken out by cooling. And a method of laminating blow molding. 2. A hollow product is obtained by attaching a resin sheet to the outer surface of a parison discharged from an annular resin passage between a die head and a core attached to the lower end of a mandrel, and sandwiching the resin sheet with a pair of left and right dies. It is a laminated bonding blow molding method, in which the resin sheet is projected in the parison direction from the outer periphery of the mold,
Further, a suction mechanism having a cushioning mechanism that is contractible with respect to a pressing force is held in the middle, and the suction mechanism is curved so as to be convex toward the parison in a plan view so that it is between the parison and the mold cavity surface. After hanging down and standing still, the resin sheet was sandwiched between the mold cavity surface and the parison surface, both molds were closed at a constant mold closing speed, the mold closing was completed, and blowing was performed. A laminated blow molding method, characterized in that the molded article is taken out after cooling. 3. A temperature at which the surface of the mold before or after the mold is closed is heated to a higher softening point of the softening points of either the resin sheet or the parison, whichever is higher, and the molded product can be taken out during or after the blowing. The molded product is taken out after the mold is cooled down to claim 1 or claim 2.
The laminated blow molding method described. 4. The resin sheet is preheated to a temperature lower than the softening point temperature of the resin sheet before the resin sheet is sandwiched between the die cavity surface and the parison surface to close the die. The laminated blow molding method according to any one of claims 1 to 3. 5. An inorganic material such as a metal plate, a metal foil, glass, a ceramic material, a stone material, or an organic material such as leather, paper, wood, or the like between the back surface of the resin sheet and the front surface of the parison. The bonding blow molding method according to any one of claims 1 to 4, wherein the molding is carried out by interposing the combination.