JP5176187B2 - Synthetic resin preform and biaxial stretch blow molded housing - Google Patents

Description

  The present invention relates to a synthetic resin preform for biaxial stretch blow molding and a biaxial stretch blow molded casing.

A biaxially stretched blow-molded casing made of polyethylene terephthalate (PET) resin is molded into a preform, and the preform is biaxially stretched and blown. The shape is a test tube comprising a mouth tube portion and a bottomed cylindrical portion formed on the shoulder portion, body portion, and bottom portion of the casing.
The diameter and wall thickness of this bottomed cylindrical part are the thickness of each part excluding the mouth tube part of the casing that is the final molded product, and the draw ratio related to the strength, heat resistance, and transparency of the molded product. Determine in consideration of the above.
For example, Patent Document 1 describes a preform in which the diameter of the bottomed cylindrical portion is reduced downward.

On the other hand, in Patent Document 2, an inner container, which is a thin container that can be crushed and deformed, is stored and held in an outer container that is not deformed, and a pump is attached to the combination of the inner container and the outer container. An invention relating to a double container with a pump that is configured to be detachably attached to an outer container and to allow outside air to be freely introduced between the inner container and the outer container is described. Biaxially stretched and blow-molded bodies have been used for thin inner containers.
JP 2000-211017 A Japanese Patent Laid-Open No. 2004-3007048

However, in the case of a case made by biaxial stretch blow molding, there are limits to reducing the thickness of the shoulder, body, and bottom due to various restrictions, and it is not always necessary to form a thin case as intended. May not be possible.
Here, when the shape of the casing such as the diameter of the trunk portion is determined, main means for reducing the thickness of the peripheral wall of the casing are the following A and B.
-Means A: Reduce the thickness of the peripheral wall of the bottomed cylindrical portion of the preform.
-Means B: The diameter of the bottomed cylindrical portion is reduced to increase the draw ratio.
Such thinning means A and B have the following restrictions.

-Means A The injection molding of the preform is generally performed by injection-molding molten resin into the mold cavity from the bottom through a pin gate, and finally filling the portion corresponding to the mouth tube, but with a bottomed cylindrical shape If the wall thickness is too thin, smooth flow of the molten resin is hindered, and flow turbulence occurs. Problems such as incompleteness occur.
In actual molding, the thickness reduction is about 1 to 1.5 mm.

For the means B, the diameter of the mouth tube part is determined by the use of the housing so that the diameter is determined from the necessity of inserting a pump in the case of the inner container of the double container with a pump described above, for example. In particular, the diameter of the bottomed cylindrical portion suspended from the mouth tube portion, particularly the upper end portion (corresponding to the region formed from the shoulder portion of the housing to the upper end portion of the trunk portion by biaxial stretching), is this. Since it is determined by the diameter of the mouth tube portion, there is a limit to achieve thinning by increasing the draw ratio of the portion.

That is, when the diameter of the mouth tube portion of the housing is relatively large and the diameter of the body portion is relatively small, it is difficult to achieve thinning by increasing the draw ratio.
Further, if the casing has a relatively large diameter and a relatively small body diameter, the draw ratio cannot be increased. There is also a problem that rigidity, strength, heat resistance, and transparency in a region extending to the upper end are insufficient.

Accordingly, the present invention provides a biaxial stretch blow-molded housing, particularly a stretch ratio in a region from the shoulder portion to the upper end portion of the body portion in a housing having a relatively large diameter of the mouth tube portion and a relatively small diameter of the body portion. It is a technical problem to create a preform configuration for increasing the thickness of the region to achieve thinning of the region.

Of the means for solving the above problems, the main configuration according to the preform of the present invention is as follows.
In a test tubular preform for axial stretch blow molding,
A bottomed cylindrical portion having an outer diameter smaller than the inner diameter of the mouth tube portion extends from the lower end of the mouth tube portion via a tapered short tube portion that decreases in diameter downward, and a tapered short tube It is said that a short cylindrical outer cylinder part is hung so as to cover the upper part of the cylindrical part and the cylindrical part, and a neck ring is provided around the lower end of the outer cylinder part in the form of an outer collar.

The basic technical idea of the above configuration is:
By adopting a double wall structure in the height range of the neck ring from the lower end of the mouth tube part, the diameter of the cylindrical part formed on the shoulder part and the body part of the housing is reduced by the diameter of the mouth tube part. It is to relax the constraints.
That is, according to the above-described configuration, a portion from the lower end of the mouth tube portion to the neck ring in the conventional preform is covered with the outer tube portion from the tapered short tube portion to the upper end portion of the cylinder portion. By making it a heavy wall,
The diameter of the portion from the mouth tube portion through the short cylindrical outer tube portion to the neck ring is determined according to the application, and separately from this, it is suspended from the lower end of the mouth tube portion through the tapered short tube portion, The diameter of the upper end portion of the cylindrical portion formed on the shoulder portion or the trunk portion of the body can be determined.

  Further, by making the diameter of the upper end portion of the cylindrical portion smaller than the diameter of the mouth tube portion, even in a case where the diameter of the mouth tube portion is relatively large and the diameter of the body portion is relatively small, The stretch ratio in the region from the shoulder portion of the body to the upper end portion of the trunk portion can be increased to achieve a reduction in the thickness of the portion.

Next, the main configuration relating to the synthetic resin casing of the present invention is as follows.
In the case of biaxial stretch blow molding,
From the lower end of the neck portion, a short cylindrical neck portion having an outer diameter smaller than the inner diameter of the mouth tube portion is suspended via a tapered short tube portion that decreases in diameter downward from the lower end of the mouth tube portion. A shoulder part and a cylindrical body part extending in the downward direction, which is a biaxially stretched molded part, are suspended and extended,
Furthermore, a short cylindrical outer cylinder part is suspended from the lower end of the mouth cylindrical part so as to cover the tapered short cylindrical part and the neck part, and a neck ring is provided around the lower end of the outer cylindrical part in an outer collar shape. It is said.

  The synthetic resin casing having the above-described configuration is a biaxial stretch blow by heating the bottomed cylindrical portion excluding the portion covered with the outer cylindrical portion at an appropriate temperature for the preform having the main configuration of the present invention described above. It can be molded by molding.

As described for the preform having the main configuration of the present invention, even if the diameter of the mouth tube portion is relatively large and the diameter of the trunk portion of the casing is relatively small, It is possible to provide a casing that achieves unprecedented thinning of the portion by increasing the stretch ratio of the portion toward the upper end.
Further, high heat resistance, mechanical strength, and good transparency can be imparted to the portion by stretch molding at a high magnification.

  According to another configuration of the synthetic resin casing of the present invention, in addition to the main configuration described above, a part of the outer surface of the shoulder is melt-bonded circumferentially to the lower surface of the neck ring. .

  The casing having the above-described structure can be formed by the so-called hot parison method in which the preform having the main structure of the present invention described above is injection-molded and then biaxially stretched and blow-molded at a high temperature without being cooled once. Simultaneously with blow molding, a part of the outer surface of the shoulder can be melt-bonded circumferentially to the lower surface of the neck ring.

In the case having the above structure, a portion of the outer surface of the shoulder portion is melt-bonded to the lower surface of the neck ring, and the portion from the neck portion to the shoulder portion is highly rigid by the tubular rib formed over the entire circumference. It can be.
As a result, even if the housing is thinned from the shoulder portion to the upper end portion of the trunk portion, the instability of the posture of the neck portion caused by the thinning of the portion can be supplemented. It can be used in a stable posture as an inner container of a heavy container.

  In addition to the main configuration described above, the other configuration related to the synthetic resin casing of the present invention is that the barrel portion is cylindrical, and the ratio of the outer diameter D1 of the mouth tube portion to the outer diameter D2 of the barrel portion is D2 / D1. The value of is in the range of 2 or less.

The effect by the main structure concerning the synthetic resin casing of this invention is notably exhibited by the casing whose D2 / D1 value is 2 or less.
That is, in the conventional case, when the value of D2 / D1 is 2 or less, it is difficult to achieve the intended thinning by increasing the stretch ratio of the portion from the shoulder portion to the upper end portion of the trunk portion. .

Since the present invention has the above-described configuration, the following effects can be obtained.
That is, in the preform having the main configuration of the present invention,
In the height range from the lower end of the mouth tube part to the neck ring in the conventional preform, by covering the part from the tapered short cylinder part to the upper end part of the cylindrical part with the outer cylinder part to make a double wall, The diameter of the portion from the mouth tube portion through the short cylindrical outer tube portion to the neck ring is determined according to the application, and separately from this, it is suspended from the lower end of the mouth tube portion through the tapered short tube portion, The diameter of the upper end portion of the cylindrical portion formed on the shoulder portion or the trunk portion of the body can be determined, and by making the diameter of the upper end portion of the cylindrical portion smaller than the diameter of the mouth tube portion, Even in a case with a relatively large diameter and a relatively small body diameter, especially by increasing the stretch ratio in the region from the shoulder of the body to the upper end of the body, it is possible to sufficiently thin the part. Can be achieved.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described along examples with reference to the drawings.
FIG. 1 is a half longitudinal front view showing an embodiment of a synthetic resin preform according to the present invention. This preform 1 is made of PET resin, and has a mouth tube portion 2 having a locking periphery provided at the upper end portion. A bottomed cylindrical portion 4 having an outer diameter smaller than the inner diameter of the mouth tube portion 2 is suspended from a lower end of the mouth tube portion 2 through a tapered short tube portion 3 whose diameter is reduced downward. Has been established. The cylindrical portion 4 is gradually reduced in diameter toward the lower side.

Further, from the lower end of the mouth tube portion 2, the cylindrical portion 4 is suspended and the short cylindrical outer tube portion 5 is suspended so as to cover the tapered short tube portion 3 and the upper end portion of the cylindrical portion 4. And has a double wall shape in the height range from the lower end of the mouth tube portion 2 to the lower end of the outer tube portion 5.
A neck ring 6 is provided around the lower end portion of the outer cylinder portion 5.
Here, in this embodiment, the inner diameter of the mouth tube portion 2 is 19 mm, the outer diameter of the upper end portion of the cylindrical portion 4 is 15.5 mm, and the minimum thickness of the upper end portion of the cylindrical portion 4 is 1.2 mm.

Next, FIG. 2 shows the preform 1 of the preform 1 shown in FIG. 1, except that the cylindrical portion 4 excluding the height range from the upper end to the lower end of the neck ring 6 is heated to an appropriate temperature and molded by a normal biaxial stretch blow molding method. 1, the shape of the preform 1 in FIG. 1 is maintained as it is in the height range from the upper end to the lower end of the neck ring 16, and the casing 11 is contracted downward from the lower end of the mouth tube portion 12. A short cylindrical neck portion 14, which is a portion corresponding to the upper end portion of the cylindrical portion 4 of the preform 1, is suspended through a tapered short cylindrical portion 13 that is diameter-shaped.
Further, a short cylindrical outer cylinder portion 15 is provided so as to cover the tapered short cylinder portion 13 and the neck portion 14, and a neck ring 16 is provided around the lower end of the outer cylinder portion 15 in the shape of an outer casing. A double wall is formed in a height range from the lower end of the mouth tube portion 12 to the lower end of the outer tube portion 15.

And below the lower end of the neck part 14, the shoulder part 17, the trunk | drum 18, and the bottom part 19 which biaxially-stretched the cylindrical part 4 of the preform 1 are droopingly extended.
Here, the average thickness at the height position indicated by A in the figure near the lower end of the shoulder portion 17 of the trunk portion 18 is 0.3 mm. The value of D2 / D1, which is the ratio of the outer diameter D1 of the mouth tube portion 12 and the outer diameter D2 of the body portion, is 1.7.

Here, the above-mentioned D2 / D1 is 2 or less, and to what extent a small casing can be supported by the preform having the configuration of the present invention, the use of the casing and the core mold used for the injection molding of the preform It is determined by the limits related to injection molding, such as how much can be made thinner.
For example, when the casing 11 of FIG. 2 is used as an inner container of a double container with a pump, it is necessary to insert a pump body portion into the neck portion 14, which corresponds to the neck portion 14. The diameter of the upper end portion of the cylindrical portion 4 of the inner preform 1 is naturally limited depending on the application.

Next, FIG. 4 shows a conventional PET resin preform. This preform 1 is provided with a cylindrical body 4 having a bottomed bottom portion and a diameter-reduced portion downward from the bottom end of the mouth tube portion 2. A neck ring 6 is provided around the lower end of the mouth tube portion 2.
Here, the inner diameter of the mouth tube portion 2 of the preform 1 of this conventional example is 19 mm, and the minimum thickness of the upper end portion of the cylindrical portion 4 is 1.2 mm.

  FIG. 5 is a case of a conventional case in which the preform 1 of FIG. 4 is biaxially stretch blow molded, and the shape of the case 11 from the mouth tube portion 12 to the neck ring 16 is the mouth of the preform 1 of FIG. The shape is the same as the portion from the tube portion 2 to the neck ring 6.

Below the neck ring 16, a shoulder portion 17, a trunk portion 18, and a bottom portion 19 that are biaxially stretched from the cylindrical portion 4 of the preform 1 are provided so as to hang down through a short cylindrical neck portion 14 a.
The average thickness at the height position indicated by C in the figure near the lower end of the shoulder portion 17 of the trunk portion 18 is 0.6 mm. The value of D2 / D1, which is the ratio of the outer diameter D1 of the mouth tube portion 12 and the outer diameter D2 of the body portion, is 1.7.

Here, in the case of the embodiment of FIG. 2 and the case of the conventional example of FIG. 5, the thicknesses at the height positions indicated by A and C in the drawing near the lower end of the shoulder 17 are 0.3 mm and 0. In the case of 6 mm, which is 6 mm, it is characteristic that the thickness of the case of the conventional example is ½.
That is, in the case 11 of the embodiment of FIG. 2, by using a preform in which the diameter of the upper end portion of the cylindrical portion 4 is reduced as shown in FIG.
A casing having a relatively large diameter of the mouth tube portion and a relatively small diameter of the body portion (a value of D2 / D1 which is a ratio of the outer diameter D1 of the mouth tube portion 12 and the outer diameter D2 of the body portion is 2 or less (this In the examples, it was confirmed that sufficient thinning was achieved even in the case of 1.7)).

  Then, the entire casing excluding the mouth tube section 12 is formed by making the wall thickness about 0.3 mm including the shoulder portion 17 and the upper end portion of the trunk portion 18 as in the casing 11 of FIG. Can be sufficiently achieved, and sufficient performance can be exhibited as an inner container of a double container with a pump.

Next, FIG. 3 shows a second embodiment of the housing of the present invention. This housing 11 is biaxially stretched at a high temperature without being cooled once after the preform 1 of FIG. 1 is injection molded. Blow molding is performed by a so-called hot parison method.
The feature of the housing 11 of the second embodiment is that a part of the outer surface of the shoulder 17 is melted and bonded to the lower surface of the neck ring 16 at the same time as blow molding. The tube-shaped rib formed over the circumference can make the portion from the neck portion 14 to the shoulder portion 17 highly rigid,
Thereby, even in the case of a frame thinned to about 0.3 mm from the shoulder portion 17 to the upper end portion of the trunk portion 18, the instability of the posture of the neck portion 14 due to the thinning of the portion in particular is compensated. Can do.

The preform for biaxial stretch blow molding of the present invention is stretched in a region from the shoulder portion to the upper end portion of the trunk portion in a casing having a relatively large diameter of the mouth tube portion and a relatively small diameter of the trunk portion. The magnification can be increased to sufficiently achieve the thinning of the region, and a wide range of usage expansion to the inner container of the double container with a pump is expected.

It is a vertical front view which shows one Example of the preform of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of a first embodiment of a synthetic resin casing of the present invention partially cut longitudinally. It is a front view which shows a 2nd example of a synthetic resin casing of the present invention partially longitudinally. It is a vertical front view which shows the prior art example of a preform. It is a front view which shows the conventional example of a synthetic resin casing partially longitudinally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Preform 2; Mouth part 3; Tapered short cylinder part 4; Cylindrical part 5: Outer cylinder part 6; Neck ring 11; Housing 12; Mouth part 13; Tapered short cylinder part 14; ; Neck part 15: outer cylinder part 16; neck ring 17; shoulder part 18; trunk part 19;

Claims (4)

This is a test tubular preform for biaxial stretch blow molding, and the mouth tube part (2) via a tapered short tube part (3) whose diameter decreases downward from the lower end of the mouth tube part (2). A bottomed cylindrical portion (4) having an outer diameter smaller than the inner diameter of the short cylindrical portion (4) is suspended and extended so that the upper ends of the tapered short cylindrical portion (3) and the cylindrical portion (4) are externally mounted. A synthetic resin preform characterized in that an outer cylinder part (5) is suspended and a neck ring (6) is provided around the lower end of the outer cylinder part (5) in the shape of an outer casing. It is a casing made by biaxial stretch blow molding, and is smaller than the inner diameter of the mouth tube portion (12) through a tapered short tube portion (13) whose diameter is reduced downward from the lower end of the mouth tube portion (12). A short cylindrical neck portion (14) having an outer diameter is suspended from the lower end of the neck portion (14), and a shoulder portion (17) and a cylindrical shape that expands downward from a biaxially stretched molded portion. A barrel portion (18) extends downward, and further, a short cylindrical outer cylinder portion (12) is provided so as to cover the tapered short cylinder portion (13) and the neck portion (14) from the lower end of the mouth tube portion (12). A synthetic resin casing characterized in that 15) is suspended and a neck ring (16) is provided around the lower end of the outer cylinder (15) in the form of an outer casing. The synthetic resin casing according to claim 2, wherein a part of the outer surface of the shoulder (17) is melt-bonded circumferentially to the lower surface of the neck ring (16). The body part (18) is cylindrical, and the value of D2 / D1, which is the ratio of the outer diameter D1 of the mouth tube part (12) and the outer diameter D2 of the body part, is set to 2 or less. Synthetic resin housing.

Images