JP2514376B2 - Sealing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for sealing a container, and more specifically, a container lid made of a metal sheet shell and a synthetic resin liner material is attached to the mouth and neck of a synthetic resin container. The present invention relates to a sealing method for sealing a container.

<Prior art and its problems> Recently, as containers for beverages and the like, containers made of synthetic resin such as polyethylene terephthalate (PET) have been widely put into practical use instead of glass containers. It's coming. The sealing of the mouth and neck of such a synthetic resin container is generally performed by a container lid composed of a metal sheet shell and a synthetic resin liner material, as in the case of a glass container.

However, the synthetic resin container generally has lower rigidity and heat resistance than the glass container. Therefore, conventionally, the sealing of the synthetic resin container had the following problems to be solved.
That is, in the case of a synthetic resin container, when the container is exposed to a relatively large temperature change due to heat filling of the contents or heat sterilization treatment after filling the contents, excessive shrinkage is generated in the mouth and neck, Due to this, the sealing of the mouth and neck by the container lid is impaired, or the so-called necessary opening torque that needs to be applied to the container lid at the time of opening is excessively reduced (in this case, the consumer needs to open the container until opening). I had a doubt about the seal).

Therefore, in order to form a support that resists radial deformation of the mouth and neck of the container, the central portion of the top wall of the shell of the container lid is axially pressed into the mouth and neck of the container lid to hang it in a cylindrical shape. A method has been proposed in which the outer peripheral surface of the hanging cylindrical portion is made to coincide with the cylindrical inner peripheral surface of the mouth / neck portion (JP-A-60-1938).
(See Japanese Patent No. 50).

This method has been proposed to solve the above problems, but in addition to this, the following other problems newly occur.

(1) The opening (opening) torque increases.

The outer peripheral surface (liner) of the indicator cylindrical portion that hangs down into the mouth and neck of the container is in contact with the cylindrical inner peripheral surface of the mouth and neck. Therefore, when the container lid is rotated when the container is opened, these contact surfaces move in the axial direction while rotating relatively, so that the frictional force increases (the container lid has friction in the rotation direction and the axial direction (withdrawal direction). Occurs). These frictions continue until the container lid moves in the axial direction and the outer peripheral surface of the supporting cylindrical portion separates from the inner peripheral surface of the mouth / neck portion, and the frictional force is not abruptly reduced as the container lid is rotated. Absent. Especially, processing error,
When the pressure on the contact surface is increased due to contraction of the mouth and neck, the frictional force is further increased and the opening torque of the container lid is excessively increased, which makes opening difficult.

(2) A high processing system is required.

In order to prevent the neck and neck of the container from contracting, particularly high processing accuracy (dimensional accuracy) is required when molding the outer peripheral surface of the support cylindrical portion and the cylindrical inner peripheral surface of the container neck and neck, and molding is extremely difficult. is there.

(3) Since the center portion of the top wall of the shell of the container lid is axially pressed into the mouth and neck of the container to form the supporting cylindrical portion that hangs down into the mouth and neck, the deformation of the top wall of the shell is large, Therefore, a large load is required for the deformation, which makes molding difficult. In particular, the mouth-neck portion of the container lid that functions as a lower mold during molding is made of synthetic resin, and if a large load is applied during processing, it may be deformed or damaged, and its reliability is not sufficiently ensured.

As is clear from the above description, according to the conventional method, although the contraction of the mouth-neck portion of the container can be dealt with, the above-mentioned problem newly occurs and further improvement is required.

<Problems of the invention> The present invention has been made in view of the above facts, and its main technical problem is to improve the sealing method of sealing the container by mounting the container lid on the mouth and neck of the container, The object is to prevent excessive contraction from being generated in the mouth and neck of the container even when exposed to various temperature changes, and to eliminate all the above-mentioned problems that have newly occurred.

<Solution to the Invention> According to the present invention, an inclined inner portion that is inclined upward in the radial direction is formed on the annular top surface of the substantially cylindrical mouth / neck portion, and below the inclined inner portion. A synthetic resin container on which a cylindrical inner peripheral surface following it is formed, a metal thin plate shell having a circular ceiling wall and a cylindrical skirt wall hanging down from the peripheral edge of the ceiling wall, and the ceiling wall of the shell. In a method of mounting and sealing a container lid made of a synthetic resin liner material for sealing disposed on an inner surface; corresponding to the inclined inner side portion of the annular top surface of the mouth / neck portion of the ceiling wall of the shell Applying a pressing force to the annular region to incline the annular region downward inward in the radial direction, and press the liner material on the inclined inner portion without pressing on the cylindrical inner peripheral surface. A sealing method is provided.

<Operation of the Invention> According to the sealing method of the present invention, the slanted inner portion, which is slanted upward toward the radial outer side of the annular top surface of the mouth-neck portion of the container, has a direction in which it resists contraction of the mouth-neck portion. A pressing force having a component is applied from the container lid, and the pressing force maintained by the relatively large rigidity of the container lid effectively prevents contraction of the mouth and neck, thus creating excessive contraction in the mouth and neck. Is avoided.

According to the sealing method of the present invention, all the other problems described above are solved. That is, in the present invention, in the ceiling wall of the shell, by applying a pressing force to the annular region corresponding to the inclined inner portion of the annular top surface of the mouth and neck, the annular region is inclined downward inward in the radial direction, Liner material
The liner material is contacted (pressed) only on the annular top surface including the inclined inner side portion of the mouth and neck of the container, because the liner material is contacted (pressed) without pressing on the inner cylindrical surface. (There is no contact of the outer peripheral surface of the liner of the supporting cylindrical portion with the inner cylindrical surface of the neck portion of the container as in the conventional method). Therefore, the contact area between the liner material and the container is small, and as the container lid is rotated, the liner material is separated from the annular top surface, whereby the frictional force is rapidly reduced, so that the container lid can be easily opened. The opening torque does not increase significantly.

Further, according to the sealing method of the present invention, when sealing a container in which the container lid is attached to the mouth and neck of the container, a pressing force is applied to a predetermined annular region on the ceiling wall of the shell of the container lid, and the annular region is radiused. Inclining downward inward in the direction, thus without pressing the liner material against the cylindrical inner peripheral surface,
It is pressed against the inner slope of the annular top surface of the mouth and neck. Since a high sealing effect can be easily obtained by pressing the liner material to the inclined inner side portion, particularly high processing accuracy is not required.

Furthermore, according to the sealing method of the present invention, the amount of deformation of the top surface wall of the shell of the container lid is small, so that the load for deformation is small. Therefore, molding is easy. In particular, since the mouth and neck of the container that functions as the lower mold at the time of molding is made of synthetic resin, the load acting during processing is small, so there is almost no possibility of deformation or damage, and its reliability is sufficiently secured. To be done.

Preferred embodiments of the present invention Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 illustrates a mouth / neck portion of a container to which the sealing method of the present invention is applied. Polyethylene terephthalate (PE
Can be formed from a suitable synthetic resin such as T),
The container, which may be of a form known per se, comprises a mouth-neck 2 of substantially cylindrical shape. On the outer peripheral surface of the mouth / neck portion 2, a male screw thread 6 and an annular locking jaw portion 8 located below the male screw thread 6 are formed. As clearly shown in FIG. 2, the annular top surface 10 of the mouth / neck portion 2 has a slanted inner portion 12, a horizontal middle portion 14, and an arcuate outer portion which are slanted downward in a radial outward direction.
Have 16. Below the inclined inner portion 12, a cylindrical inner peripheral surface is formed continuously therefrom.

FIG. 3 illustrates a container lid 18 used to seal the mouth-neck 2 of a container, which may be of a form known per se. The container lid 18 is composed of a metal sheet shell 20 and a synthetic resin liner material 22. The shell 20, which can be formed from a suitable metal sheet such as an aluminum-based alloy sheet, a tin sheet or a chromic acid treated steel sheet, is a substantially flat circular top wall 24 and a cylindrical skirt that hangs from the periphery of the top wall 24. With wall 26. A weakening line 28 extending in the circumferential direction is formed on the skirt wall 26, and the skirt wall 26 has a main portion 30 above the weakening line 28 and a weakening line 28.
It is partitioned into a pilfer proof skirt 32 below. The weakening line 28 includes a plurality of circumferentially spaced slits (cutting grooves) 34 and the slits 34.
It is defined by the bridge portion 36 existing between them. The main portion 30 of the skirt wall 26 is formed with knurls or uneven shapes 38 and 40 at its upper end portion and lower end portion so as to prevent the sliding of a finger applied thereto. Further, the main portion 30 has an annular recess functioning as a guide means for the screw forming roller when forming a female thread on the main portion 30 as described later.
42 are also formed.

The liner material 22 disposed on the top wall 24 of the shell 20 can be formed of a suitable synthetic resin material such as polyethylene, polypropylene or polyvinyl chloride. The liner material 22 can be formed directly on the inner surface of the ceiling wall 24 of the shell 20 by a well-known embossing method. Alternatively, a liner material separately formed in the required shape can be inserted into the shell 20 and positioned at the required position. Liner material shown
22 is a disc shape as a whole, and has a concentric shape on the periphery.
Strip ridges, namely outer ring ridge 44 and inner ring ridge 46
Have.

When the container lid 18 shown in FIG. 3 is attached to the mouth / neck portion 2 of the container shown in FIG. 1 to seal the mouth / neck portion 2, first, the container lid 18 is fitted onto the mouth / neck portion 2. Next, as shown in FIG. 4, a required pressing force is applied to the container lid 18 by the pressing tool 48 that is brought into contact with the top wall 24 of the shell 20, and the liner material 22 is pressed against the annular top surface 10 of the mouth / neck portion 2. wear. Then, while such a state is maintained, a female thread is formed on the main portion 30 of the skirt wall 26 of the shell 20 along the male thread 6 of the mouth / neck portion 2 by an appropriate thread forming roller (not shown). Article 50
To form. Also, the lower end of the pilfer proof hem 32 in the skirt wall 26 of the shell 20 is deformed radially inward by an appropriate bending roller (not shown), and the locking jaw 8 of the mouth / neck 2 is deformed. Lock it on the bottom.

Thus, in the present invention, when the container lid 18 is mounted on the mouth / neck portion 2 of the container as described above, the required annular region 52 on the top wall 24 of the shell 20 of the container lid 18, that is, the mouth / neck portion 2
It is important to apply a pressing force to the annular region 52 located corresponding to the inclined inner portion 12 of the annular surface 10 so that the annular region 52 is inclined downward inward in the radial direction.
In the illustrated specific example, in order to satisfy such requirements, a pressing tool 48 in which an annular protrusion 54 is formed in a portion of the ceiling wall 24 of the shell 20 that contacts the annular region 52 is used. . When the pressing tool 48 is applied to the ceiling wall 24 of the shell 20 and a required pressing force is applied, the annular projection 54 of the pressing tool 48 is applied.
By this, the annular region 52 of the top wall 24 of the shell 20 is inclined downward inward in the radial direction, and thus the top wall 24 is deformed from the substantially flat state shown by the two-dot chain line to the form shown by the solid line. Be punished. The ceiling wall 24 of shell 20 is readily understood by reference to FIG.
Inclining the annular region 52 inwardly downward in the radial direction increases the pressing force of the liner material 22 against the inclined inner side portion 12 of the annular top surface of the mouth / neck portion 2 and increases the liner material.
22 is pressed firmly against the inclined inner side portion 12 of the annular top surface 10. Inclined inner part 12 on the annular top surface 10 of the mouth / neck part 2
Is inclined radially outwardly, so that the pressing force applied from the liner material 22 to the inclined inner portion 12 is a component directed radially outward, that is, a component which resists contraction of the mouth / neck 2. Have. The pressing force continues to be maintained by the metal shell 20 having a relatively large rigidity. Therefore, according to the sealing method of the present invention, as will be clearly understood from Examples and Comparative Examples described later, even when the container is exposed to a relatively large temperature change, the mouth and neck 2 is excessively contracted. Is reliably avoided.

In the embodiment described above, the ceiling wall 24 of the shell 20 is substantially flat until the annular region 52 is deformed by the annular protrusion 54 during mounting, but before mounting, as shown in FIG. Already an annular region on the ceiling wall 24 of Ciel 20
Using the container lid 18 in which 52 is pre-tilted slightly radially inwardly, an annular ridge 54 of the pressing device 48 exerts a pressing force on the annular region 52 during mounting. Can be further deformed and tilted downward inward in the radial direction.

Also, if desired, the annular region 52 of the top wall 24 during mounting may be
As shown in Fig. 6, the top wall is deformed.
The outermost peripheral region of 24 or the boundary region between the top wall 24 and the skirt wall 26 can be deformed downward.

When opening the mouth / neck portion 2 of the container sealed by the container lid 18 mounted as described above, the container lid 18 is rotated counterclockwise when viewed from above in FIG.
Thus, the female thread 50 formed on the main portion 30 of the skirt wall 26 moves along the male thread 6 of the mouth / neck portion 2,
The container lid 18 does not move upward with rotation. However, the lower end of the pilfer proof hem 32 has the mouth / neck 2 locking jaw 8 locked to the lower surface, and is prevented from moving upward. Thus, considerable stress is created in the weakening line 28 in the skirt wall 26, and more particularly in its bridging portion 36, causing the weakening line 28 to break and separating the pilfer proof skirt 32 from the main portion 30. Thereafter, except for the Pilfer proof hem 32, the container lid 18 can freely rise with rotation and is removed from the mouth neck 2.

<Examples and Comparative Examples> Example 1 As a container, "General heat resistance 1.5" was obtained from Toyo Seikan Co., Ltd.
(PET bottle having a nominal diameter of 38 mm), which is sold as a PET bottle, and a container made of polyethylene terephthalate having a configuration as illustrated in FIGS. 1 and 2 was used.

As a container lid, (a) print and vinyl-based protective lacquer on one side of a 0.25 mm thick aluminum-based alloy sheet, and coat polyethylene oxide containing epoxy paint on the other side, and (b) coat polyethylene oxide containing epoxy paint. Pressing is performed so that the coated surface is on the inside, and the third
High-pressure polyethylene (density = 0.92, melt index = 4.0) melted at 220 ° C in the shell that was previously heated to 180 ° C after forming the shell as shown in the figure (c).
Was used, and the container lid was used, which was embossed and molded into a liner material having the same shape as shown in FIG.

Then, (i) 87 ° C. hot water filling test, (ii) 93 ° C. hot water filling test, (iii) empty sealed 85 ° C. test, and (iv) empty sealed 93
A ° C test was performed.

(I) In the 87 ° C warm water filling test, use 87 ° C warm water in the container.
1.5 Fill, then attach the container lid to seal the mouth and neck, then lay the container on its side for 30 seconds, and then tap water for about 10 minutes.
Cooled for a minute.

The (ii) 93 ° C. hot water filling test was the same as the (i) 87 ° C. hot water filling test, except that the 93 ° C. hot water was filled instead of the 87 ° C. hot water.

(Iii) In the air-sealed 85 ° C test, attach the container lid to the mouth and neck when the container is empty, and then cut the shoulder of the container to separate the mouth and neck from the trunk, and then remove the mouth and neck from 85 ° C. It was immersed in warm water at ℃ for 3 minutes, and further cooled with tap water for 3 minutes.

(Iv) The air-sealed 93 ° C test was the same as (iii) the air-sealed 85 ° C test, except that it was immersed in 93 ° C warm water instead of 85 ° C warm water.

In any test, when attaching the container lid to the mouth and neck of the container, a pressing tool having a configuration as shown in FIG. 4 was used to apply a pressing force of 180 kg to the ceiling wall of the shell of the container lid. In addition, the predetermined annular region of the top wall is inclined downward inward in the radial direction by the annular projection of the pressing tool. The downward protrusion amount t of the annular protrusion was 1.75 mm, and the diameter d of the lowermost end of the annular protrusion was 27.4 mm (Fig. 4).

For each of the above tests, the average value of the upper inner diameters of the mouth and neck of 30 containers before the test was performed (29.545mm) was compared with the average value of the upper inner diameters of the mouth and neck of 30 containers after the test was performed. It was measured how it changed. The results are shown in Table 1 below.

Example 2 The same test and measurement as in Example 1 were carried out except that the protrusion amount t of the annular protrusion of the pressing tool used when attaching the container lid to the mouth and neck of the container was 2.25 mm. Carried out
The results are shown in Table 1 below.

Comparative Example For comparison, when attaching the container lid to the mouth and neck of the container, a pressing tool having no flat annular projection and a flat lower surface was used (so that the top wall of the shell is not deformed). The same tests and measurements as in Example 1 were carried out except that they were kept flat). The results are shown in Table 1 below.

Considering the measurement results shown in Table 1, when the container lid is attached to the mouth and neck of the container, according to the present invention, the predetermined annular region on the top wall of the shell is pressed to move radially downward inward. It is clearly understood that the inclination of the tongue significantly reduces the contraction of the mouth and neck caused by the temperature change.

<Effects of the Invention> According to the sealing method of the present invention, excessive shrinkage is not generated in the mouth and neck of the container even when exposed to a large temperature change. In addition, all the problems that have newly occurred can be solved. That is, since the frictional force for opening the container is not particularly large while the sealing effect is maintained, the container lid can be easily opened, and the opening torque does not increase significantly. Further, there is no need for specially high processing accuracy. Furthermore, the amount of deformation of the shell top wall is small, and the load for deformation is also small, so molding is easy and the mouth and neck of the container is deformed.
There is almost no possibility of breakage, and its reliability is sufficiently secured.

[Brief description of drawings]

FIG. 1 is a side view showing an example of a mouth / neck portion of a container to which the sealing method of the present invention is applied, in a partial cross section. FIG. 2 is a partial sectional view showing a part of the mouth / neck portion of the container of FIG. FIG. 3 is a side view showing an example of a container lid attached to the mouth and neck of the container shown in FIG. 1 in a partial cross section. 4 is a partial cross-sectional view showing one manner of mounting the container lid of FIG. 3 on the mouth and neck of the container of FIG. FIG. 5 is a side view, partly in section, of a modified example of the container lid mounted on the mouth and neck of the container shown in FIG. 1. FIG. 6 is a partial cross-sectional view showing a modified manner in which the container lid of FIG. 3 is attached to the mouth and neck of the container of FIG. 2 …… Container neck 10 …… Annular top of mouth neck 12 …… Inclined inner part 18 …… Container lid 20 …… Ciel 22 …… Liner material 24 …… Ciel top wall 26 …… Ciel skirt wall 48 …… Pressing tool 52 …… Annular area of top wall 54 …… Annular ridge of pressing tool

 ─────────────────────────────────────────────────── --Continued from the front page (56) References JP 58-193266 (JP, A) JP 60-193850 (JP, A) JP 57-68353 (JP, A) Actual 62- 174056 (JP, U) Actual public Sho 50-36029 (JP, Y1)

Claims (2)

(57) [Claims] 1. An annular inner surface of a substantially cylindrical mouth-neck portion is formed with a slanted inner portion that is slanted upward in the radial direction, and below the slanted inner portion, a slanted inner portion is formed. A synthetic resin container having a peripheral surface is formed by sealing a thin metal sheet shell having a circular ceiling wall and a cylindrical skirt wall hanging down from the peripheral edge of the ceiling wall and an inner surface of the ceiling wall of the shell. In a method of mounting and sealing a container lid made of a synthetic resin liner material for use in the sealing; a pressing force is applied to an annular region of the ceiling wall of the shell corresponding to the inclined inner portion of the annular top surface of the mouth and neck. A sealing method in which the annular region is inclined downward inward in the radial direction, and the liner material is pressed against the inclined inner portion without being pressed against the cylindrical inner peripheral surface. 2. Even before applying a pressing force to the annular region, the annular region is preliminarily inclined downward inward in the radial direction, and by applying the pressing force, the annular region is further directed in the radial direction. The sealing method according to claim 1, wherein the sealing method is inclined downward.