JPH0957831A - Lamination blow molding method - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To provide a bonded blow molding method capable of obtaining a smooth and high quality bonded blow molded product having no steps and having excellent surface transferability without defects such as wrinkles and bubbles. To do. In a bonding blow molding method, a mold cavity surface is heated in advance to a softening point temperature of the resin sheet or the parison, whichever is higher, and then the mold is clamped and blown to obtain a molded product. A method for laminating blow molding in which a molded article is taken out by cooling to a temperature sufficient to remove the degassing discharge hole, which comprises a plurality of fine cuts penetrating from the front surface to the back surface. It has been drilled.

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 product in which a resin sheet is bonded to the surface of a parison, and in particular, the adhesion between the resin sheet and the main resin is good, and wrinkles and The present invention relates to a bonding blow molding method capable of obtaining a high-quality resin sheet bonded molded product having an excellent appearance without defects such as bubbles.

[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 bonded to the surface. The production of blow-molded articles has traditionally been practiced.

[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. In addition, by simply sandwiching the flat resin sheet between the mold and the parison and performing blow molding, wrinkles are formed on the surface of the molded product, bubbles remain, and the molded product has a poor gloss and poor appearance. Can be done. Therefore, a plurality of fine through holes are previously formed 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. It is also possible to discharge air that is present between the two to make them adhere to each other, but in this case, the fine through holes in the resin sheet are complicated and costly, and at the same time, the fine through holes penetrate the surface of the molded product after molding. The problem that the traces of the holes, which are traces of the holes, remain and impair the external appearance has occurred again. 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]

[Means for Solving the Problems] In order to solve the above problems, a high-quality bonded blow-molded product having a smooth gloss and a smooth surface without wrinkles or bubbles remaining In the present invention, in the first 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 a pair of left and right molds are used. In a bonding blow molding method of sandwiching and forming a hollow product, after heating the mold cavity surface above the softening point temperature of the resin sheet or the parison, whichever is higher, the mold is clamped and blown. A method of laminating blow molding in which a molded article is taken out by cooling to a temperature sufficient to remove the molded article after the molding, The deaerating discharge holes consisting of fine Do notch was formed by a plurality bored configuration. Further, in the second invention, the fine cut shape formed in the resin sheet is any one of a broken line, a cross character, an X character, an * mark, a US mark, or a combination thereof, and the size of the cut shape is 0.1
The range was ˜1 mm. Further, according to a third aspect of the present invention, in the first or second aspect of the present invention, before the resin sheet is sandwiched between the die cavity surface and the parison surface to close the die, the resin sheet is previously attached to the resin sheet. It was preheated to a temperature lower than the softening point temperature of. And 4th invention WHEREIN: In the 1st invention-3rd invention, the inorganic material, 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 According to the present invention, in the bonding blow molding method, the mold cavity surface is heated in advance to the softening point temperature of the resin sheet or the parison, whichever is higher, and then the mold is closed. A method for laminating blow molding in which a molded product is cooled and cooled to a temperature sufficient to allow the molded product to be taken out, and the resin sheet comprises a plurality of fine cuts penetrating from the front surface to the back surface. Since a plurality of degassing discharge holes are provided, degassing during blow molding is sufficiently performed, and moreover,
Since the mold is heated to a temperature higher than the softening point temperature of either the resin sheet or the parison resin, the parison and the resin sheet are fused and integrated, and the surface of the resin sheet is also highly transferred to the mold cavity surface. From the above, an excellent molded product having a beautiful smooth surface with an appearance without surface defects can be obtained.
In the second invention, the degassing discharge hole provided in the resin sheet is
Since the cut is made of a broken line, a cross, an X, a *, a US mark, or a combination thereof, the cut portion is easily heated and closed after deaeration during blow molding is completed. No trace of holes remains. 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 of the resin sheet and the front of the parison, a metal plate,
By forming with inorganic material such as metal foil, glass, ceramic material, stone material, or organic material such as leather, paper, wood, etc., or a combination thereof, a wider product group can be obtained. be able to.

[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 a perspective view of a blow molding machine, and FIG. 3 is a cross-sectional view showing a surface state of a bonded blow-molded product. FIG. 4, 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 FIGS. 1 and 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 die head 2 is provided above the mold 8.
The roll 20 wound with the resin sheet S formed by a flat plate and having a plurality of cuts h perforated on the surface thereof at a position where the parison P discharged from the parison P hangs down the roll base 22. Is provided through. A roll base 22 is attached to the lower end of the roll 20, and the air cylinder 30
A cutter receiving seat 30b is provided which is provided with a cutter 30 whose tip is formed by a sharp edged tool that moves horizontally in the direction of the parison horizontally by the operation of a, and which has a groove portion in front of which a blade tip of the cutter 30 is fitted. Is provided, and the suspended resin sheet S can be cut at any time without damaging the surface of the parison P. In addition, a sheet clip 24 for gripping the lower end of the resin sheet S and holding the resin sheet S vertically downward during operation is provided with the mold 8.
Is provided at the lower end of the.

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.
A medium passage 8a for heating or cooling the cavity surfaces of the molds 8, 8 is provided, and is connected to a medium (heat medium or refrigerant) switching supply device (not shown). 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, the mold 8 is provided with a collecting duct 10 so as to cover the outside of the mold 8 in order to positively suck the air discharged from the vent holes 8b, and the electromagnetic valve 12 and the suction fan. Exhaust pipe 1 with 14
1 is 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 resin sheet S may be made of the same kind of resin as the parison P, or may be made of a different kind from the parison P. 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, preferably 0.5.
A thin film having a thickness of not more than mm is desirable. 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, a notch h penetrating to the back surface of the resin sheet as a degassing discharge hole for discharging the air present between the parison P and the resin sheet S when pressure-bonding with the parison P. A plurality of holes are drilled. The shape of the notch h is, as illustrated in FIG. 2, a broken line, a cross, an X, and *.
Marks or rice marks, or a combination of them, provided in a grid or in a zigzag arrangement. Its size is 0.1 mm to 1 mm in length
Range, preferably 0.1 mm or more and 0.5 mm or less, and the array density is at least 1 per 100 cm ^2, but preferably 4 to 500 per 100 cm ^2. . The reason is that if the length of the cut h is 0.1 mm or less, it is too small to discharge gas, and if it is 0.3 mm or more, traces of holes are likely to remain after molding, and the lower limit of the array density (10
1 or more per 0 cm ² ) is determined from the minimum required gas discharge area, and the upper limit of the array density (100 cm)
⁽ 500 or less per ² ) comes from the fact that the effect of gas discharge is the same even if more than this is provided. However, when the elongated ribbon-shaped resin sheet S is locally attached to the surface of the parison P, the notch h may be omitted (since the intervening air deviates from the left and right ends of the ribbon-shaped resin sheet S. , Do not need the cut h).

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 wound down from the roll 20 and hung down, and the lower end is pinched by the sheet clip 24, and held in the vertically stretched state. Then, the parison P is discharged from the lower end of the die head 2 by 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, the upper end of the resin sheet S is horizontally cut by the cutter 30, and the parison P is molded while the resin sheet S is attached to the surface of the parison P. On the cavity surfaces of the molds 8 and 8, the temperature is in the vicinity of the softening point of the resin sheet S, the surface of the resin sheet S is softened and melted, and the mold cavity surface is pressed and the mold cavity surface is transferred. The surface of the parison and the surface of the resin are pressure-bonded together and bonded by the pressurized air blown into the parison P via the blow pin. Further, the notch h provided in the resin sheet S is also crushed and closed after the blow molding, leaving no trace.

The discharge hole for degassing provided in the resin sheet S is
As shown in FIG. 6, in the case of not the cut h but the fine through hole H and there is no "return" at the time of drilling, the surface of the molded product is not removed even after the bonding molding. There is a fear that the holes will remain and spoil the beauty. Therefore, in order to improve this problem, in the present invention, the resin sheet S is
For example, the cut h is formed in the resin sheet S as described above without using the fine through holes. As a result, as shown in FIG. 5, a convex protrusion 60 is formed on one of the cuts h. When the surface on which the convex projection 60 is formed faces the mold surface and is then clamped by being interposed between the mold surface and the parison surface, the convex projection 60 of the cut h is pressed and pushed. As a result of being crushed, the notch h is closed and the hole mark disappears. The method of forming the notch h on the surface of the resin sheet S is, for example, provided by passing cold or hot between rolls having a blade upper protrusion protruding and attached to the surface, or a blade-like protrusion. A method of press punching with a certain press machine is adopted.

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 plates, 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.

[0017]

As described above, in the present invention,
In the laminating blow molding method, after heating the mold cavity surface in advance to the softening point temperature of the resin sheet or the parison, whichever is higher, the mold cavity is clamped and blown sufficiently to take out the molded product. A method for laminating blow molding in which a molded product is taken out by cooling to a proper temperature, wherein a plurality of degassing discharge holes consisting of a plurality of fine cuts penetrating the front surface to the back surface are formed in the resin sheet. , The degassing ability is improved, and wrinkles and air bubbles (air accumulation) do not remain on the molded product. In addition, the cuts are such that, when the resin sheet is heated during blow molding, the surfaces are melted and fused to each other to be closed, so that the appearance can be kept beautiful. Therefore, it is possible to obtain a high-quality molded product having a beautiful appearance and a smooth transfer property, which is free from defects such as wrinkles and bubbles on the surface of the molded product. Further, by freely selecting the color of the resin sheet, it is possible to easily, easily and inexpensively produce a multi-color, 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. Furthermore, 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 a perspective view of a blow molding machine according to an 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 Die Head (Die) 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 base 24 Sheet clip 30 Cutter 30a Air cylinder 30b Cutter seat 40 Metal foil 50 Step 60 Protruding protrusion P Parison S Resin sheet H Fine through hole h Notch (deaeration discharge hole)

Claims (4)

[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. In the continuous bonding blow molding method, the mold cavity surface is heated in advance to the softening point temperature of the resin sheet or the parison, whichever is higher, and then the mold is clamped to blow the molded product so that the molded product can be taken out. The method is a bonding blow molding method in which a molded product is taken out after cooling to a sufficient temperature, wherein a plurality of degassing discharge holes each having a plurality of fine cuts penetrating the front surface to the back surface are formed in the resin sheet. Blow-molding method that consists of: 2. The fine cut shape formed in the resin sheet is any one of a broken line, a cross, an X-shape, a * mark, a US mark, or a combination thereof, and the size of the cut shape is 0.1. The method of laminating blow molding according to claim 1, wherein the range is ˜1 mm. 3. The resin sheet is preheated to a temperature lower than the softening point of the resin sheet before the resin sheet is sandwiched between the die cavity surface and the parison surface to close the die. A method for laminating blow molding according to claim 2 or claim 3. 4. 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 claim 1, wherein the molding is carried out by interposing the combination.