JPH0957832A - Blow molding method using heat insulating sheet therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blow molding method, which is excellent in surface transferability and with which smooth and high quality blow molded article or laminated blow molded article is obtained. SOLUTION: In this blow molding method, molds 8 and 8 are closed under the condition that a Teflon or polyamide heat insulating sheet S is interposed in advance between the cavity surface of the mold and the surface of a parison and then the air is blown in the parison so as to obtain a blow molded article.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow molding method using a heat insulating sheet, and in particular, it does not require heating of a mold during blow molding and has a high gloss and a high transferability, and has an excellent appearance. The present invention relates to a blow molding method using a heat insulating sheet that can obtain a quality blow molded product or a bonded blow molded product obtained by laminating decorative sheets.

[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. 4 shows a conventional blow molding machine. 4 shows a so-called side-feed type blow molding machine 1 for supplying molten resin from one side of the die head 2, and the resin in a high temperature molten state 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. The methods are roughly classified as follows. Method of heating and cooling the mold In this method, in order to improve the surface property of the blow molded product, the mold cavity surface is heated by a heating means (mold heat by oil, heating by far infrared rays, induction heating). . Method using heat-insulating mold The surface of the mold cavity is coated with a heat-insulating material to improve the surface property by the latent heat of the parison itself. Method of transferring by performing embossing (concavo-convex processing) on the surface of the mold In order to enhance the decorativeness of the surface of the molded product, irregularities of various patterns or patterns are applied and transferred on the mold cavity surface.

[0004]

However, each of the above methods has the following problems. That is, in any of the methods of heating and cooling the mold, there is a problem in that the cost for heating the mold is high and the molding cycle is longer than that in normal molding, so that productivity is reduced. In the method using the heat insulating mold, the cooling property is slightly inferior and the molding cycle becomes long. Further, there is a problem that the durability of the coating material is poor. Furthermore, in the method of transferring by performing embossing (concavo-convex processing) on the mold surface, the mold production cost rises and the cost becomes high, and it is stocked separately from the mold with a normal smooth cavity surface. There are difficulties that must be addressed.

[0005]

[Means for Solving the Problems] By solving the above problems, high-quality blow-molded products and bonded blow-molded products with excellent surface properties that are free of wrinkles and bubbles and have smooth gloss. In order to obtain the present invention, in the first invention, the parison discharged from the annular resin passage between the die head and the core attached to the lower end of the mandrel is sandwiched by a pair of left and right molds to be hollow. A blow-molding method for producing a product in the shape of a ring, in which a Teflon- or polyamide-made heat-insulating sheet is preliminarily interposed between the mold cavity surface and the parison surface to close the mold and blowing is performed. Is to get.
Also, in the second invention, in the first invention, the blow-molded product is formed by sandwiching the decorative sheet having the decorative pattern or the decorative pattern between the heat insulating sheet and the surface of the parison. It is a thing. Further, according to a third invention, in the first invention or the second invention, a metal plate, a metal foil, a glass, between the back surface of the decorative sheet and the front surface of the parison,
Inorganic materials such as ceramics and stones, leather, paper,
It was decided to form by interposing either one of organic materials such as wood or a combination thereof.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the blow molding method according to the present invention, a heat insulating sheet made of Teflon or polyamide is preliminarily interposed between the mold cavity surface and the parison surface to close the mold, and blowing is performed. I went to get a blow molded product. Therefore,
The same effect as the heat insulation mold can be achieved easily and easily, and since the heat insulation sheet can be selected arbitrarily, any decorative pattern or decoration pattern can be applied to the surface of the molded product without replacing the mold. Can be given. Further, in the case of producing a bonded blow-molded product, a decorative sheet for laminating a parison is sandwiched between a heat insulating sheet and a parison, and the mold is clamped and blow-molded. And, as the decorative sheet, it is possible to obtain molded articles having various designs and designs by freely selecting colors or adopting a resin sheet on which decorative patterns and decorative patterns are printed in advance. it can.
Further, between the decorative sheet back surface and the parison surface, either 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 or wood,
Alternatively, a further expanded product group can be obtained by molding with a combination thereof.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 3 relate to an embodiment of the present invention, FIG. 1 is an overall vertical sectional view of a blow molding machine, FIG. 2 is an overall vertical sectional view of a blow molding machine showing another embodiment, and FIG. It is sectional drawing which shows the surface state of a molded product. FIG.
In the blow molding machine 1, a pair of left and right molds 8, 8 are disposed below the die head 2 of the blow molding machine 1 so as to be freely contactable and separable, and above the mold 8 is discharged from the die head 2 and hung down. A pair of upper and lower rolls 20, 20 wound with a heat insulating sheet S such as Teflon or polyamide is disposed at a position hanging downward along the surface of the parison P via a roll base 22 laid on one mold 8. To be done. Rolls 20, 2
0 can be wound up if necessary, or can be fixed to rotate as it is in a substantially stretched state. On the other hand, in the embodiment of FIG. 2, the roll 20 and the like for the heat insulating sheet described above are provided, and further, the roll 20,
A roll 30 in which a decorative sheet (resin sheet) T is wound is provided inside 20 and the like, and a roll base 32 is attached to the lower end of the roll 30. The roll 30 moves back and forth horizontally in the parison direction by operating an air cylinder 34a. A cutter receiving seat 34b is provided in which a cutter 34 whose front end is formed of a sharp blade is provided, and a cutter receiving seat 34b having a groove portion to which the cutting edge of the cutter 34 is fitted is provided in the front of the cutter receiving seat 34b. Can be cut at any time without damaging the parison P surface. In addition, holding the lower end of the decorative sheet T,
A sheet clip 36 for holding the decorative sheet T vertically extended downward during operation is provided at the lower end of the mold 8.

The decorative sheet T may be made of the same resin as the parison P, or may be made of a resin different from the parison P. The decorative sheet T may be a multilayer resin sheet, 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.). Good. However, since the sheet material attached to the burrs may be crushed and reused for the next molding shot, basically the same material as the parison P is desirable. The thickness of the decorative sheet T 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.
A thin film having a thickness of not more than mm is desirable. If the decorative sheet T 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 decorative sheet T may be damaged during molding.

The surface of the decorative sheet T is provided with degassing discharge holes for discharging the air existing between the parison P and the decorative sheet T when pressure-bonding with the parison P. It is also possible to make a plurality of cuts that penetrate up to. The shape of the cut is, for example, one of a broken line, a cross, an X, a *, and a US mark, or
A combination of them is provided, and a plurality of them are arranged in a grid pattern or a zigzag pattern. Its size is 0.1 in length
mm to 1 mm, preferably 0.1 mm or more
0.5mm or less, the array density is at least 1
One or more per 00 cm ² , preferably 100 c
It is desirable that the number is 4 or more and 500 or less per m 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 (100 cm ² (1 or more per 1) is determined from the minimum required gas discharge area, and the upper limit of array density (500 or less per 100 cm ² ) is the same even if a larger number is provided. Comes from.
However, when the elongated ribbon-shaped decorative sheet T is locally attached to the surface of the parison P, the cut may be omitted (the intervening air deviates from the left and right ends of the ribbon-shaped decorative sheet T). So I don't need a notch).
When the decorative sheet T is provided with a notch for deaeration and discharge, of course, a plurality of deaeration through holes are also provided in the heat insulating sheet, and the die 8 is provided with a deaeration through hole for suction. It is necessary to install equipment to do so.

The blowing pressure of the blowing after closing the mold completely eliminates the air between the surface of the parison P and the decorative sheet T attached to the surface of the parison P, leaving air between them to leave the surface of the molded product. In order to prevent defects such as the formation of bubbles,
The pressure is at least 4 kgf / cm ² .

The softening temperature of the resin is equal to the glass transition temperature in the case of the amorphous resin, and 110 ° C. to 1 in the case of the ABS resin.
30 ° C., 120 ° C. to 140 ° C. for modified PPO resin
It is a degree. 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 after the temperature of the molded product falls below this temperature, the mold is opened and the product is taken out.

On the surface of the decorative sheet T on the parison contact side,
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 of FIG. 1 configured as above will be described. First, while holding both molds 8 and 8 in the mold open state, the heat insulating sheet S is wound down from the roll 20 and hung down to gently fix both the upper and lower rolls 20 and 20. next,
After the parison P is discharged from the die 2 and hung down to stand still, the mold is closed and blown into the parison P for blow molding. During this operation, the surface of the parison is pressed strongly against the mold cavity surface by the pressurized air blown into the parison P via the blow pin via the heat insulating sheet S, and the parison P is formed of molten resin at a high temperature. The latent heat of is reduced by the speed at which it is shielded by the heat insulating sheet S and dissipated from the mold cavity surface, that is, the same effect as when the mold 8 is used as a heat insulating mold is exerted, and the parison surface has a mold cavity. A smooth molded article having a good surface property is formed by highly transferring the surface. The blow molding machine 1A of FIG. 2 is for molding a bonded blow molded product, and similarly to the blow molding machine described above, after the heat insulating sheet S is stretched to the front surface of the mold by the rolls 20 and 20, the decorative sheet T is formed. Is wound down from the roll 30 and the lower end is gripped by the sheet clip 36, and then the parison P is discharged and drooped to stand still. Similarly, the parison P is closed and blown into the parison P for blow molding. During this operation, the front surface of the parison and the back surface of the decorative sheet T are pressure-bonded integrally with each other by the pressurized air blown into the parison P via the blow pin, and the heat insulating sheet S is interposed in front of the decorative sheet T. Similarly, the high-temperature latent heat of the parison P is sufficiently transferred to the decorative sheet T, the parison P and the decorative sheet T are fused and integrated with each other to obtain high adhesion, and the surface side of the decorative sheet T is The heat transfer sheet surface is highly transferred regardless of the mold cavity surface. That is, the inside of the heat insulating sheet S (on the parison side) is in a temperature state near the softening point of the decorative sheet T because of latent heat of the parison, and the mold sheet side of the decorative sheet T is also in a molten state. If there is a decorative pattern or decorative pattern on the parison side of the sheet S, it is easily transferred to the decorative sheet. Further, since the notch for deaeration and discharge provided in the decorative sheet T is also in a high-temperature molten state, it is crushed and closed after blow molding, and no trace is left.

The method of forming the cuts on the surface of the decorative sheet T is, for example, provided by cold or hot passing between rolls having a blade upper protrusion protruding and attached to the surface, or A method of press punching with a press having a blade-shaped projection is adopted.

The decorative sheet T used in the laminated blow-molded product of the present invention may be a normal commercial product produced by extrusion molding, but a decorative pattern is provided on one side (the surface side of the blow-molded product). By using, for example, an ABS extruded sheet on which a decorative pattern is printed, it is possible to obtain various panel-shaped molded articles having high gloss and arbitrary colors and patterns. 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, a heat insulating sheet having the same effect as that of the heat insulating die is adopted instead of heating the die at the time of closing the blow molding die. Therefore, the resin sheet T is heated and softened to a semi-molten state. Therefore, the surface of the molded product can form a smooth surface having no step as shown in FIG. 3 without forming the step 50 as in the pasted molded product of the conventional method as shown in FIG. .

[0017]

As described above, in the present invention,
In the blow molding method, a heat insulating sheet made of Teflon or polyamide was previously interposed between the mold cavity surface and the parison surface to close the mold, and blown to obtain a blow molded product. The same effect as a heat-insulating mold, which is expensive to manufacture, can be obtained easily and easily, and a beautiful molded product with high transferability and high surface property can be obtained. Further, since the heat insulating sheet can be easily replaced against deterioration during use, maintainability is improved. Further, by sandwiching the decorative sheet between the heat insulating sheet and the parison and performing blow molding, a bonded molded product having high transferability and a high surface can be obtained. Furthermore, by freely selecting the color of the decorative 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 using a decorative pattern, a decorative sheet with a decorative pattern added and a decorative pattern, a heat insulating sheet with unevenness of the decorative pattern, without using a die that has been subjected to expensive uneven processing, You can enjoy the variety of designs and designs. Furthermore, in the method of the present invention, since the heat insulating sheet is used, the surface of the decorative sheet in contact with the mold cavity surface is softened and remelted, and there is no step at the boundary between the end of the decorative sheet 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 overall vertical sectional view of a blow molding machine according to another 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 an overall vertical sectional view of a conventional blow molding machine.

FIG. 5 is a cross-sectional view showing a surface state of a conventional bonded blow-molded product.

[Explanation of symbols]

 1 Blow Molding Machine 1A 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 20 Roll 22 Roll Stand 30 Roll 32 Roll Stand 34 Cutter 34a Air Cylinder 34b Cutter Seat 36 Sheet Clip 40 Metal Foil 50 Step P Parison S Insulation Sheet T Decorative Sheet

Claims (3)

[Claims] 1. A blow molding method in which a parison discharged from an annular resin passage between a die head and a core attached to a lower end of a mandrel is sandwiched by a pair of left and right molds to form a hollow product. , Teflon or polyamide insulation sheet is inserted between the mold cavity surface and the parison surface in advance to close the mold, and blown to obtain a blow molded product. Blow molding method. 2. A blow molding using the heat insulating sheet according to claim 1, wherein a blow molded article is formed by sandwiching a decorative sheet having a decorative pattern or a decorative pattern between the heat insulating sheet and the surface of the parison. Method. 3. 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 decorative sheet and the front surface of the parison, or A blow molding method using the heat insulating sheet according to claim 1 or 2, wherein the blow molding is performed by interposing a combination thereof.