JPH0558892B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for molding a biaxial stretch blow-molded bottle made of synthetic resin and a mold apparatus for carrying out this method. The object of this invention is to stretch-form the mouth tube part by the same biaxial stretching process as the body part and the bottom part.

Biaxial stretch blow-molded bottles made of polyethylene terephthalate resin have come to be used in large quantities in a wide range of fields because they exhibit a variety of excellent physical properties and durability extremely effectively through biaxial stretch molding. There is.

As described above, bottles made by biaxial stretch blow molding have many excellent advantages, but the conventional biaxial stretch blow molding method does not apply stretching to the mouth of the molded bottle. Because I can't give,
There was a serious drawback in that the effect of biaxial stretching could not be achieved only in the mouth barrel of the bottle.

In other words, the mouth part of the conventional biaxial stretch blow molded bottle is molded without undergoing biaxial stretching, so it is inferior in heat resistance, hardness, and transparency compared to the body and bottom of the bottle. However, it has disadvantages such as the formation of many thin crazes due to the penetration of alcohol, which tends to cause whitening.

This defect in the neck part of the biaxially stretched blow-molded bottle is extremely serious, and the field of application of the biaxially stretched blow-molded bottle is greatly restricted due to this defect of the neck part. I was getting used to it.

The present invention was devised to solve the above-mentioned drawbacks of the conventional example, and the present invention will be explained below with reference to the drawings.

The present invention is similar to the conventional biaxial stretch blow molding method, in which the molding material is pre-injection molded into a cylindrical shape with a bottom.
The next molded product S1 is uniformly heated to a temperature that produces a stretching effect and then biaxially stretched blow molded into a bottle S3. It has a bottomed cylindrical shape with a diameter sufficiently smaller than the diameter of the mouth barrel portion S3' of the body S3, and has a structure in which a flange S1' is provided around the outer periphery of the open end.

The primary molded product S1 having such a structure is uniformly heated to a temperature that produces a stretching effect, and is assembled at the open end into a stretching jig 8 having a stretching pin 9, as shown in FIG. It is moved in the direction of the arrow shown in and assembled into the blow mold 1 together with the stretching jig 8.

By assembling the stretching jig 8 to the blow mold 1, the flange S1' of the primary molded product S1 is immovably held between the blow mold 1 and the stretching jig 8.

When the assembly of the stretching jig 8 to the blow mold 1 is completed, and when the mold clamping of the blow mold 1 is completed and the state shown in FIG. 2 is reached, the stretching pin 9 is advanced. Then, as shown in FIG. 3, the primary molded product S1 is stretched in the axial direction to a height greater than the bottle S3 to be molded.

At the same time as or around the end of the stretching of the primary molded product S1 in the axial direction, the stretching pin 9
Pressurized fluid is injected into the primary molded product S1 through the air passage formed inside, and the primary molded product S1 is radially blow-molded (see Figure 4) to form a biaxial stretch blow-molded product S2. .

During the blow molding operation of this primary molded product S1, at least the 1
The S1 part of the next molded product is caused by the pressure from the pressure fluid.
In order to make deformation molding easier and more accurate, the viscosity of the material does not increase due to heating.

As shown in FIG. 4, the heating of the portion formed in the mouth barrel S3' of the bottle S3 is stopped when the biaxial stretch blow molding operation of the primary molded product S1 into the product S2 is completed. Thereafter, the cooling is switched to complete the biaxial stretch blow molding in the same manner as the other parts of the product S2.

When the biaxial stretch blow molding of the primary molded product S1 into the product S2 is completed, the product S is removed from the blow mold 1.
Release 2 from the mold.

Product S2 molded from this primary molded product S1
Since the primary molded product S1 is stretched to a greater height than the target molded product S3, a shape is added to the primary molded product S1 at the upper end of the mouth tube S3' of the target molded product S3. It has a structure in which a cylindrical piece S2' having a rounded flange S1' is attached.

Therefore, from the released product S2, the cylindrical piece S
The molding of the molded product S3 is completed by cutting out the portion 2'.

The method for molding the molded product S3, which is a bottle body according to the present invention, consists of the above-mentioned molding steps.
It is preferable to start heating the portion of the next molded product S1 from the time when the first molded product S1 is assembled into the blow mold 1 together with the stretching jig 8.

This is the primary molded product S to be molded into the mouth barrel S3'.
Part 1 cools down slower than other parts,
For this reason, when it is stretched in the axial direction, it is more susceptible to stretching than other parts, and the part of the primary molded product S1 that is formed into this mouth tube part S3' is This is also because it is located close to the opening of the primary molded product S1 to be assembled into the jig 8, and is therefore a part that is easily cooled by heat conduction.

In addition, the heating applied during the stretch blow molding operation is not necessarily limited to the portion of the primary molded product S1 that is molded into the mouth tube portion S3'. For example, when increasing the heat resistance of the molded product S3, , heat setting may be performed by heating the entire primary molded product S1.

As described above, the method of the present invention can biaxially stretch mold the mouth tube portion S3' of the molded product S3, which is a bottle, and a mold that is advantageous for carrying out the molding method of the present invention. An example of the device will be described below.

In the illustrated embodiment, the blow mold 1 includes a bottom mold 6 that provides a bottom mold surface, and at least two split molds 2 that provide mold surfaces from the body to the neck.
It is composed of a mouthpiece mold 3 that provides a mouthpiece mold surface.

The mouthpiece mold 3 also serves as a part for assembling the stretching jig 8 to the blow mold 1, and the mold surface 3' of the mouthpiece mold 3 and the stretching jig 8 are It is separated by a relatively large distance from the assembly surface 3'' to be assembled, and a stretching jig 8 assembled to the blow mold 1 is attached to the inner peripheral end of this assembly surface 3''.
A presser bulge 15 is bulged inwardly between the stretching jig 8 and the flange S1' of the primary molded product S1 assembled to the stretching jig 8.

This presser bulge 5 clamps the vicinity of the peripheral end of the flange S1' with the stretching jig 8, and therefore the inner diameter of the bulge 5 itself is the outer diameter of the cylindrical portion of the primary molded product S1. The value is larger than the diameter.

Moreover, the temperature of this mouthpiece mold 3 is controlled completely separately from the bottom mold 6 and the split mold 2, and therefore there is a gap between the split mold 2 and the mouthpiece mold 3. A heat insulating material 7 is arranged to minimize mutual influence as much as possible.

Further, a through hole 4 is formed in the mouthpiece mold 3 so that the temperature of the mouthpiece mold 3 is independently controlled, and a heating fluid and a cooling fluid are selectively supplied into the through hole 4. It is becoming more and more common.

The mold apparatus having the above structure is operated in the following order.

First, prior to the stretch-molding operation, heating fluid is supplied to the through hole 4 to heat the mouthpiece mold 3 to a desired temperature.

From this state, as shown in FIG. 1, the stretching jig 8 with the primary molded product S1 heated to a temperature at which the stretching effect is produced is assembled into the blow mold 1 to achieve mold clamping.

By the way, when assembling the stretching jig 8 with the primary molded product S1 assembled into the blow mold 1, conventionally the blow mold had to be in an open state, but in the case of the present invention, 1 Since the diameter of the cylindrical wall portion of the next molded product S1 is sufficiently smaller than the diameter of the mouth barrel portion S3' of the bottle body S3, the first molded product The stretching jig 8 to which S11 has been assembled may be assembled to the blow mold 1.

After the mold device has clamped, the primary molded product S is produced using the same procedure as the conventional biaxial stretch blow molding operation.
1 is molded into a product S2, but during this biaxial stretch blow molding, the mouth tube part S3' of the molded product S3
The part of the primary molded product S1 to be molded, that is, the part facing the mold surface 3' of the mouthpiece mold 3, maintains its soft state due to the heat of the mouthpiece mold 3 and maintains its final shape. It is molded into the mouth barrel portion S3'.

In this way, once the blow molding operation has been completed and the product 2 has been molded, the supply of heating fluid to the through holes 4 is stopped and instead cooling fluid is supplied to the through holes 4 to form the mouthpiece. Cool the mold 3.

At the time when this mouthpiece mold 3 is cooled, that is, when the mouthpiece part S3' is cooled by this mouthpiece mold 3, the other product S2 part has already been cooled by the split mold 2 and the bottom mold 6. or has been switched from a heating state to a cooling state,
After this cooling process is completed, the mold device is opened to release the product S2, and then, as described above, the cylindrical piece S2' is cut out from the product S2 to complete the molding of the molded product S3.

In this way, in the present invention, all parts forming the molded product S3 are sufficiently stretched in the axial direction, and similarly, the diameter of the cylindrical wall portion of the primary molded product S1 is
Since the diameter of the mouth barrel part S3' of the molded product S3 to be molded is sufficiently smaller, the mouth barrel part S3' is also sufficiently stretched in the radial direction, so that the molded product S3 is All parts will be fully biaxially stretched.

In addition, during the blow molding operation, since the portion of the primary molded product S1 that is molded into the mouth barrel portion S3' of the molded product S3 is heated, that is, the mouth barrel mold 3 is heated, so that the primary molded product S1 is heated. The part of the molded product S1 is kept in a sufficiently soft state, so that even the mouth part S3', which has a complicated shape with threads, neck rings, etc., can be molded accurately and reliably. .

As is clear from the above description, in the present invention, the entire bottle, which is a molded product, can be formed by applying biaxial stretching, so that the excellent effects of biaxial stretching can be applied almost uniformly to the entire bottle. As a result, the field of use of this type of bottle can be greatly expanded, and the molding operation itself is almost the same as the conventional one, just adding the cutting of the cylindrical piece S2', so the work is easy. It is easy to do,
Furthermore, it has many excellent functions and effects, such as being able to accurately and reliably mold even a mouth barrel portion S3' having a complicated shape.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing the process of assembling the primary molded product into the blow mold, Fig. 2 is a longitudinal sectional view showing the mold clamping state, and Fig. 3 is a longitudinal sectional view showing the process of stretching in the axial direction. , Fig. 4 is a vertical cross-sectional view showing the blow molding process, Fig. 5 is a front view of the main part showing the state in which the cylindrical piece has been removed and the molded product has been formed, and Fig. 6 is the mouth tube in Fig. 2. FIG. 7 is an enlarged sectional view of the vicinity of the mouth mold part of FIG. 4. Explanation of symbols, 1...Blow mold, 2...Split mold, 3...Bout mold, 3'...Mold surface, 3''...Assembling surface, 4...Through hole, 5... Presser foot bulge, 6... Bottom mold, 7... Insulating material, 8... Stretching jig, 9...
Stretch pin, S1...primary molded product, S1'...flange, S2...product, S2'...cylindrical piece, S3...
... Molded product, S3'... Mouth barrel part.

Claims (1)

[Claims] 1. A primary molded product made of synthetic resin in the shape of a bottomed cylinder, which has a flange around the outer periphery of the opening end and has a diameter sufficiently smaller than the mouth of the bottle to be molded, is stretched. After heating it to a temperature where it becomes effective, it is fixed with the flange and stretched in the axial direction to a height greater than the bottle body, and blow molding is performed with at least the part to be formed into the mouth barrel part of the bottle body being heated. A method for forming a biaxial stretch blow-molded bottle made of synthetic resin, in which, after the biaxial stretch blow molding operation is completed, a cylindrical piece shaped at the upper end of the mouth barrel part of the released product is cut out and molded into a bottle body. . 2 Consisting of a bottom mold, at least two split molds, and a mouthpiece mold, the mouthpiece mold is provided with a through hole through which a heating fluid and a cooling fluid pass, and a mouthpiece mold. A presser bulge that clamps a flange provided around the outer periphery of the opening end of the primary molded product assembled to the stretching jig, at a position sufficiently away from the plane, between the stretching jig and the stretching jig to be assembled. A mold device for molding a synthetic resin biaxially stretched blow-molded bottle, comprising: