JP2004026168A - Synthetic resin container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve molding sealability and prevent a molding flaws. <P>SOLUTION: A synthetic resin container has a locking protrusion 15 of an outer tube 14 of an inner plug 8 locked with an engaging recess 12 of a mouth 11 by capping and an inner tube 16 of the inner plug in pressure contact with the inner peripheral surface of the mouth. In the container, the internal diameter Ro on the side of the tip 11a of the mouth is formed to be larger than the internal diameter R1 on the side of the back 12a of the engaging recess, and the tip 16a of the inner tube is in pressure contact with the inner peripheral surface of the back face of the engaging recess. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a synthetic resin container such as a plastic bottle, for example, a PET bottle.
[0002]
[Prior art]
A conventional PET bottle is formed through the following steps.
(1) Preform molding step: By injection molding, polyethylene terephthalate (PET) in a molten state is pressure-fed from an injection device through a gate of a preform mold into the mold to form a preform.
(2) Blow molding step: After the preform is extracted from the preform mold, the preform is sandwiched between the product molds, and air is blown into the preform to inflate the preform so that the preform is in close contact with the mold.
(3) Cooling step: The expanded preform is cooled in the mold to make a finished product (pet bottle), and then the mold is opened and the PET bottle is taken out.
[0003]
[Problems to be solved by the invention]
The conventional example has the following problem.
(1) Normally, when filling a PET bottle with contents, the contents are filled at a high temperature for sterilization. After that, a cap having an inner plug is attached to the mouth of the PET bottle by using a stopper device. In order to prevent leakage of the contents, an inner cylinder (inner ring) of the inner stopper is attached to the mouth. It is strongly pressed against the inner peripheral surface of. For this reason, the mouth that is easily deformed by the heat of the high-temperature contents is pushed outward by the inner cylinder and deformed, and a gap is generated between the mouth and the inner cylinder, which may cause a seal leak. is there.
[0004]
(2) In molding the PET bottle, the resin melted by heating is injected from the gate at the bottom of the preform mold and reaches the mouth mold. Therefore, the mouth is filled with the resin at last. Will be. However, before the resin reaches the mouth, the outer portion in contact with the mold gradually hardens, and the preform molding space becomes narrow. For this reason, the mouth cannot be completely filled, which may cause molding defects such as sink marks.
[0005]
The present invention has been made in view of the above circumstances, and has as its object to improve sealability. Another object is to prevent occurrence of molding defects.
[0006]
The present invention is a synthetic resin container provided with an engagement concave portion on an outer peripheral surface of the mouth portion for engaging the engagement convex portion of the inner plug; It is characterized in that it is formed to be larger than the inner diameter on the back side of the joint recess.
[0007]
The present invention relates to a synthetic resin in which an engaging concave portion of an outer cylinder of an inner plug is engaged with an engaging concave portion of a mouth portion by tapping, and the inner cylinder of the inner stopper is pressed against an inner peripheral surface of the mouth portion. The inner diameter of the front end of the mouth is formed larger than the inner diameter of the back of the engagement recess, and the front end of the inner cylinder is formed on the inner peripheral surface of the back of the engagement recess. It is characterized by being pressed.
[0008]
The present invention is characterized in that the inner peripheral surface on the tip end side of the mouth and the inner peripheral surface on the back side of the engagement recess are continuous via an arc-shaped step. According to the present invention, the inner diameter of the distal end portion of the mouth portion is formed to have a reference size.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
The present inventor has found that the distal end side of the mouth of the container is easily deformed by the influence of heat or the like, but the engaging concave portion of the mouth comes into contact with the locking convex portion of the inner plug, and the deformation is regulated. I noticed. Therefore, the inner diameter of the back side of the engagement concave portion is formed smaller than the inner diameter of the distal end portion so as to be thick, and the distal end portion of the inner cylinder is strongly pressed against the inner peripheral surface.
[0010]
In order to prevent the occurrence of molding defects, when forming a preform, the injection pressure may be increased, or the temperature of the resin may be increased to increase the fluidity of the resin, thereby completely filling the mouth. Conceivable. However, this causes other defects such as burrs and the like, and the molding cycle becomes longer, thereby lowering productivity.
In view of the above, the inner diameter of the mouth portion is configured as described above to increase the thickness of the engagement recess side, thereby solving the above problem.
[0011]
【Example】
An embodiment of the present invention will be described with reference to FIGS.
The preform mold 1 includes a main body mold 1a, a mouth mold 1b, and a center mold 1c. The inner diameter R0 of the forming portion for the tip portion of the mouth mold 1a is formed to a size as specified, for example, RO = φ27.6 mm, and the inner diameter R1 of the engaging concave portion forming portion is formed smaller than the inner diameter R0. For example, R1 = φ27.2 mm, and the inner diameter R2 of the lower portion of the engagement recess forming portion is smaller than the inner diameter R1, for example, R2 = φ26.8 mm.
[0012]
The inner peripheral surface of the inner diameter RO and the inner peripheral surface of the inner diameter R1 are continuous via an arc-shaped step portion 13, and the inner peripheral surface of the inner diameter R1 and the inner peripheral surface of the inner diameter R2 are also interposed via the arc-shaped step portion 13. It is continuous. Therefore, two smooth steps are formed on the inner peripheral surface of the mouth.
[0013]
A mold 1 is provided with a preform molding space 2 through which a molten resin (molten resin) passes. The preform molding space 2 is connected to a hot runner 4 via a gate 3 at the bottom of the mold 1. Have been. This hot runner 4 communicates with the injection device 5.
[0014]
When the molten resin, for example, PET in a molten state is pressure-fed to the hot runner 4 by the injection device 5, the molten resin enters the main body molding die 1a from the gate 3 and rises in the preform molding space 2. At this time, before the molten resin reaches the mouth forming die 1b, the molten resin already supplied into the preform molding space starts to solidify from the outer peripheral side in direct contact with the die.
[0015]
However, since the inner diameter R1 of the engagement concave portion is formed to be smaller than the inner diameter RO of the distal end portion of the mouth and is thick, even if the molten resin starts to solidify and the molten resin flow path becomes narrow as described above, the required size is maintained. A molten resin flow path can be secured.
Therefore, the molten resin can reliably reach the upper end of the mouth, and a preform as designed can be obtained.
[0016]
Next, the mold 1 is disassembled, the preform 6 is taken out, inserted into a product mold (not shown), and sandwiched. Thereafter, air is blown into the preform 6 to inflate it, and the preform 6 is brought into close contact with the mold, and then cooled in the mold. The mold is opened, and the cooled PET bottle (product container) 10 is taken out.
[0017]
As shown in FIG. 2, the plastic bottle 10 is provided with an engagement concave portion 12 on the outer periphery of the mouth portion 11, and the inner diameter RO of the tip portion 11a has a size as specified, for example, RO = φ27.6 mm, the inner diameter R1 on the back side of the engagement recess 12 is R1 = φ27.2 mm, and the inner diameter R2 on the lower portion 12b side of the engagement recess 12 is R2 = φ26.8 mm. .
Therefore, since the inner diameters R0, R1, and R2 of the mouth are different, the inner peripheral surface of the mouth 11 is stepped, but the step is an arc-shaped step 13, so that the inner periphery The surface is smoothly continuous.
[0018]
The PET bottle 10 is filled with a high-temperature liquid content. A cap having an inner plug 8 is plugged and attached to the mouth 11 of the bottle 10 using a plugging device (not shown).
[0019]
Then, the locking projection 15 of the outer cylinder 14 of the inner plug 8 is locked to the engagement concave portion 12, and the inner cylinder 16 is pressed against the inner peripheral surface of the mouth 11.
[0020]
In addition, a pouring cylinder 18 is provided above the inner plug 8, and the pouring cylinder 18 is closed by a blocking wall 17. Further, a screw portion 19 that is screwed with a lid (not shown) is provided outside the pouring cylinder 18.
[0021]
The mouth portion 10 is sandwiched between the outer tube 14 and the inner tube 16, but deforms in a high-temperature atmosphere, and its distal end portion 11a expands outward.
Then, a gap is generated between the inner peripheral surface of the distal end portion 11a and the outer peripheral surface of the proximal end portion of the inner cylinder 16. However, at this time, the engaging concave portion 12 is pushed inward by the locking convex portion 15, and the distal end portion 16 a of the inner cylinder 16 is in pressure contact with the back surface 12 a of the engaging concave portion 12. There is no leakage of the seal.
[0022]
Since the rear surface 12a protrudes inward from the inner peripheral surface of the front end portion 11a and is thick, the contact pressure with the front end portion 16a is strong. Therefore, since a high sealing force can be maintained, there is no sealing leakage.
[0023]
The embodiment of the present invention is not limited to the above. For example, the present invention is applicable not only to plastic bottles such as plastic bottles formed by preforms but also to synthetic resin containers formed by ordinary molds. Can also be used.
[0024]
【The invention's effect】
The present invention has the following effects.
(1) Since the inner diameter of the front end side of the mouth is formed larger than the inner diameter of the back side of the engaging recess, the resin in the molten state smoothly flows in the preform molding space during preform molding or the like. Therefore, the resin can be sufficiently filled up to the mouth. Therefore, unlike the conventional example, molding defects such as sink marks do not occur.
[0025]
(2) The inner diameter of the distal end side of the mouth is formed to be larger than the inner diameter of the rear side of the engaging concave portion, and the distal end portion of the inner cylinder is pressed against the inner peripheral surface of the rear side of the engaging concave portion. Therefore, even if the distal end of the mouth portion is deformed due to high heat, the engaging concave portion is pressed against the locking convex portion to restrict the displacement, and the rear surface of the engaging concave portion is the inner peripheral surface of the distal end portion. Since it protrudes more inward and is formed thick, a strong sealing force can be maintained. Therefore, the sealed state can be reliably maintained.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, showing a preform.
FIG. 2 is an enlarged vertical sectional view showing a part of a mouth portion of the plastic bottle.
FIG. 3 is an enlarged longitudinal sectional view of a main part of the plastic bottle with a cap attached.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Preform mold 8 Inner stopper 10 PET bottle 11 Mouth 12 Engagement concave part 14 Outer cylinder 15 Engagement convex part 16 Inner cylinder

Claims (4)

A synthetic resin container provided with an engagement concave portion on the outer peripheral surface of the mouth for engaging the engagement convex portion of the inner plug;
A synthetic resin container, wherein the inner diameter of the mouth on the tip end side is formed larger than the inner diameter on the back side of the engagement recess. In the synthetic resin container, the stopper is engaged with the engaging projection of the outer cylinder of the inner plug in the engaging recess of the mouth, and the inner cylinder of the inner plug is pressed against the inner peripheral surface of the mouth. ;
The inner diameter of the mouth on the tip end side is formed to be larger than the inner diameter of the engagement recess on the back side,
A container made of a synthetic resin, wherein a distal end portion of the inner cylinder is in pressure contact with an inner peripheral surface on a back side of the engagement concave portion. The inner peripheral surface on the tip end side of the mouth portion and the inner peripheral surface on the back side of the engagement concave portion are continuous through an arc-shaped stepped portion. Container made of synthetic resin. The synthetic resin container according to claim 1, wherein an inner diameter of the mouth at a tip end side is formed to a standard size.

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