JP4309175B2 - Plastic cap - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plastic cap, and more particularly to a plastic cap that is applied to a container that contains a content liquid having a high internal pressure, such as a carbonated beverage.
[0002]
[Prior art]
A so-called linerless type cap is known as a plastic cap, and such a linerless type cap has an inner ring and an outer ring formed on the inner surface of the top plate portion. That is, with the cap closed, the upper end portion of the container mouth wall enters between the inner ring and the outer ring, and the seal is formed by holding the upper end portion of the container mouth wall between the two. It has a structure.
[0003]
By the way, the linerless type plastic cap as described above has a problem that when it is applied to a container containing a liquid content such as a carbonated beverage, the seal is liable to break. That is, in a container containing such content liquid, since the pressure in the container is high, the cap swells into a dome shape due to the internal pressure (dome deformation), and at the same time, deformation of the inner ring and the outer ring occurs. Further, there is a problem in that the adhesion between the outer ring and the upper end portion of the container mouth portion inserted between the outer ring and the outer ring is impaired, and as a result, the seal is broken.
[0004]
In order to solve such a problem, the present applicant firstly made a plastic cap in which an outer ring is inclined radially inward and a thin wall portion having an appropriate width is formed at the base portion of the inner ring of the top plate portion ( A synthetic resin container lid) was proposed (see Patent Document 1).
[0005]
[Patent Document 1]
JP 2000-109105 A (FIGS. 2 to 6)
[0006]
That is, the cap of the above-mentioned prior art is formed by the close contact between the outer ring and the container mouth wall, and the dome deformation of the cap due to the internal pressure of the container is positively generated from the base of the inner ring. This is intended to prevent seal breakage by alleviating the stress concentration on the close contact portion between the outer ring forming the container and the container mouth wall.
[0007]
[Problems to be solved by the invention]
However, the caps of the prior art as described above are excellent in internal pressure resistance and have the advantage that seal breakage due to the internal pressure of the container is effectively suppressed, but have the disadvantage of poor label stickability. That is, a label such as a prize display is often affixed to the outer surface of the top plate portion of the cap that is attached to a container containing contents such as carbonated beverages. Inconvenience, or the attached label tends to peel off. In particular, when the container internal temperature is 40 ° C. or higher, the container internal pressure is significantly increased, and the dome deformation becomes large, so that the label sticking property is significantly deteriorated.
[0008]
Accordingly, an object of the present invention is to effectively destroy a seal due to the internal pressure of a container in a plastic cap in which a container mouth wall is held between an inner ring and an outer ring formed on the inner surface of the top plate portion to form a seal structure. An object of the present invention is to provide a plastic cap that is suppressed and has an improved label sticking property on the outer surface of the top plate portion of the cap.
[0009]
[Means for Solving the Problems]
According to the present invention, the inner wall is provided with a top plate portion and a skirt-like side wall lowered from the periphery of the top plate portion. The inner surface of the top plate portion extends downward in a substantially vertical direction and is inserted inside the container mouth wall. In the plastic cap in which the ring and the outer ring that is in close contact with the outer surface of the container mouth wall are formed, the inner ring inner portion of the top plate portion is a thin wall formed from the root portion of the inner ring to the radially inner side. An annular region and a thick circular region formed inside the thin annular region, wherein the thin annular region is formed to be the thinnest in the entire region of the top plate portion, and the thin annular region and the thick circular region A plastic cap is provided in which a ring-shaped convex portion is formed at a boundary with the region.
[0010]
In the present invention,
1. The ring-shaped convex portion has a height of 3.0 to 4.0 mm and a width of 1.0 to 2.0 mm;
2. The thin annular region has a thickness of 0.5 to 1.1 mm and a width of 0.5 to 5.0 mm, and the thick circular region has a thickness of 1.0 to 1.8 mm. to have it,
Is preferred.
[0011]
In the present invention, since the thin annular region formed at the base portion of the inner ring of the top plate portion becomes the starting point of dome deformation, and the dome deformation is generated from this portion, even when the container internal pressure rises, The adhesion between the outer ring and the upper end of the container mouth is not impaired, and at the same time, a ring-shaped convex portion is formed at the boundary between the thin annular region and the thick circular region (that is, inside the thin annular region). Therefore, the dome deformation is moderately suppressed by the ring-shaped convex portion. Therefore, it is possible to effectively avoid deterioration of label sticking due to the cap's top plate swelling more than necessary, to reliably carry out label sticking, and to avoid the disadvantage that the attached label is easily peeled off. it can.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a half sectional side view showing an example of the plastic cap of the present invention,
FIG. 2 is a bottom view of the cap of FIG.
FIG. 3 is an enlarged sectional view showing the main part of the cap of FIG. 1 together with the container mouth part,
FIG. 4 is a half cross-sectional side view showing another example of the plastic cap of the present invention,
FIG. 5 is a bottom view of the cap of FIG.
[0013]
Referring to FIGS. 1 to 3, the cap includes a top plate portion 1 and a skirt-like side wall 2 depending from the peripheral edge of the top plate portion 1. An opening history explicit band (TE band) 4 is provided via a possible bridge (for example perforation) 3.
[0014]
An inner ring 5 is formed on the inner surface of the top plate portion 1 so as to extend downward with a gap from the skirt-shaped side wall 2. An outer ring having a lower height than the inner ring is provided outside the inner ring 5. 7 is provided. A small circumferential protrusion 9 is formed between the inner ring 5 and the outer ring 7.
[0015]
A thread 10 is formed on the inner surface of the skirt-shaped side wall 2, and this thread 10 engages with a thread 51 formed on the outer surface of the container mouth wall 50. That is, by rotating the skirt-like side wall 2 in the closing direction (that is, tightening) and screwing the screw 10 with the screw 51 on the outer surface of the container mouth wall 50, this cap 50. The screw 10 has a notch formed at a position aligned in the axial direction so that the gas in the container can be quickly discharged to the outside when the cap is opened. Moreover, you may provide the axial groove | channel 10a in this notch part. With this axial groove 10a, the gas can be further quickly discharged.
[0016]
An anti-slip knurl 12 is formed on the outer surface of the skirt-like side wall 2 so that the cap can be smoothly turned in the closing direction and the opening direction.
[0017]
A known flap piece 14 is provided on the inner surface of the TE band 4 so that it can be engaged with the jaw 52 of the container mouth wall 50. That is, when the cap wound around the container mouth wall 50 is opened, the flap piece 14 comes into contact with the jaw 52 and the rise of the TE band 2 is restricted. On the other hand, the skirt-like side wall 2 is rotated and lifted in the opening direction. Accordingly, the bridge 3 connecting the lower end of the skirt-like side wall 2 and the TE band 4 is broken, and the TE band 4 is detached from the cap. Thus, the fact that the TE band 4 has been detached from the cap makes it possible to recognize the fact that the cap has been once opened or the seal has been broken.
[0018]
In particular, as clearly shown in FIG. 3, in the state where the cap is attached to the container mouth wall 50, the upper end portion of the container mouth wall 50 enters between the inner ring 5 and the outer ring 7, An annular small protrusion 9 abuts on a corner portion between the upper end surface 50a and the outer surface 50b. That is, a seal inside the container is formed by the outer ring 7 and the small annular protrusion 9 or by holding the inner ring 5, the outer ring 7 and the small annular protrusion 9 at three points.
[0019]
In the present invention, the inner ring 5 is substantially vertically lowered from the inner surface of the top plate portion 1 or has a convex portion formed on the outer peripheral surface thereof, and is in close contact with the inner surface of the container. The outer ring 7 is inclined inward toward the lower end thereof, and is formed so as to bite into the outer surface of the container mouth wall 50. Further, the annular small protrusion 9 is formed at the base portion of the outer ring 7 and is in close contact with the corner portion between the upper end surface 50 a and the outer surface 50 b of the container mouth wall 50. In this way, the outer seal 7 and the annular small protrusion 9 form a main seal. For this reason, the outstanding pressure | voltage resistance is ensured also with respect to the container whose internal pressure is high by filling with carbonated drinks. That is, when a main seal is formed by the close contact between the inner ring 5 and the container mouth wall 50, the seal is easily broken by deformation of the inner ring 5 due to deformation of the dome (bulging of the top plate 1) due to the internal pressure of the container. However, when the main seal is formed by the outer ring 7 as described above, the seal is not broken as long as the outer ring 7 is slightly deformed.
[0020]
In the present invention, the inner portion of the top plate portion 1 than the inner ring 5 is formed inside the thin annular region 30 and the thin annular region 30 formed from the base portion of the inner ring 5 to the inside in the radial direction. It has become a thick circular area 32 which are, in the boundary portion between the thin annular region 30 and the thick circular area 32, it is important that the ring convex portion 34 is formed.
[0021]
That is, the pressure resistance of the cap is further improved by the thin annular region 30 formed at the base portion of the inner ring 5. For example, when only the main seal is formed by the outer ring 7, when the temperature of the container filled with the carbonated beverage reaches a high temperature of 40 ° C. or higher, the internal pressure of the container increases significantly, and the degree of dome deformation increases. A large stress is generated in the outer ring 7 that is in close contact with the container mouth wall 50, and the deformation thereof is significant, resulting in a seal failure. However, by forming the thin annular region 30 as described above, the top plate portion 1 is dome-deformed (swells outward) starting from the base portion of the inner ring 5, so that the increase in the internal pressure of the container is caused by this dome deformation. In particular, stress concentration on the outer ring 7 is suppressed, and even in such a case, the seal breakage can be effectively prevented, and extremely excellent internal pressure resistance can be ensured.
[0022]
Further, the thick circular region 32 and the ring-shaped convex portion 34 formed on the inner side of the thin annular region 30 can be adjusted to an appropriate degree of dome deformation of the top plate portion 1, and thereby the above-described excellent The label sticking property can be improved without impairing the internal pressure resistance. That is, due to the cooperative action of the thick circular region 32 and the ring-shaped convex portion 34, even when the internal pressure of the container is remarkably increased, extreme dome deformation of the top plate portion 1 is suppressed. For example, the central portion thereof is relatively flat. It is held in a state close to. As a result, the label can be easily and reliably attached to the outer surface of the top plate portion 1 and the attached label is not peeled off. For example, when the thick circular region 32 and the ring-shaped convex portion 34 are not formed, the degree of dome deformation of the top plate portion 1 is large (the top plate portion 1 swells greatly outward), so that the peripheral portion of the label is the outer surface of the top plate portion 1. Even if pasting is difficult, or even if pasting is possible, the peripheral edge is floating, so that it is easily peeled off.
[0023]
In the present invention, it is important to adjust the degree of dome deformation by the thick circular region 32 and the ring-shaped convex portion 34. For example, the ring-shaped convex portion 34 is not formed, and the thickness of the thin annular region 30 is adjusted. Even if only the adjustment can improve the label sticking property, the deformation of the dome starting from the thin annular region 30 (that is, the base portion of the inner ring 5) is suppressed, so the stress concentration on the outer ring 7 is alleviated. This is because the internal pressure resistance is lowered and it is difficult to prevent the seal from being broken due to the internal pressure of the container.
[0024]
Therefore, in the present invention, the size of the ring-shaped convex portion 34, the width and thickness of the thin annular portion 30, the thickness of the thick circular region 32, and the like can ensure label sticking properties, but impair internal pressure resistance. It should be set so that there is no degree of dome deformation. For example, although depending on the size and material of the cap, the height H of the ring-shaped convex portion 34 (the length from the outer surface to the tip of the top plate portion 1) is usually in the range of 3.0 to 4.0 mm. And the width is preferably in the range of 1.0 to 2.0 mm, and the thin annular region 30 has a thickness of 0.5 to 1.0 mm and a thickness of 0.5 to 5.0 mm. The thick circular region 32 has a width of 1.5 to 3.0 mm, and preferably has a thickness of 1.0 to 3.0 mm.
[0025]
In the present invention, the degree of dome deformation can be adjusted by forming an appropriate rib in the thick circular region 32 in addition to the ring-shaped convex portion 34. 4 and 5 show a half-sectional side view and a bottom view of a cap formed with such a rib (denoted by 40).
[0026]
That is, in the cap of FIGS. 4 and 5, a plurality of ribs 40 (eight in the example shown in the figure) are formed from the ring-shaped convex portion 34 toward the center O of the top plate portion 1 at regular intervals. The ring-shaped convex part 34 side is high and the center O side of the top plate part 1 is low. By forming such ribs 40, the degree of dome deformation can be further finely adjusted, and the label sticking property can be effectively improved without impairing the internal pressure resistance.
[0027]
The cap of the present invention described above is injected using various plastics such as low-, medium- or high-density polyethylene, linear low-density polyethylene, polypropylene, thermoplastic polyester, polyamide, styrenic resin, and S resin. It can be manufactured by integral molding such as molding and compression molding.
[0028]
【The invention's effect】
When the plastic cap of the present invention is filled with a beverage such as a carbonated beverage and is applied to a container having a high internal pressure, it can prevent a seal breakage due to a further increase in the internal pressure due to a temperature rise, and at the same time affix the label on the outer surface of the top plate portion. It can be performed effectively and reliably.
[Brief description of the drawings]
FIG. 1 is a half sectional side view showing an example of a plastic cap of the present invention.
2 is a bottom view of the cap of FIG. 1. FIG.
3 is an enlarged cross-sectional view showing a main part of the cap of FIG. 1 together with a container mouth part.
FIG. 4 is a half sectional side view showing another example of the plastic cap of the present invention.
5 is a partial cross-sectional side view of a screw cap to which the present invention is applied. FIG.
[Explanation of symbols]
1: Top plate part 2: Skirt-shaped side wall 5: Inner ring 7: Outer ring 9: Small annular protrusion 30: Thin annular area 32: Thick circular area 34: Ring-shaped convex part 40: Rib 50: Container mouth wall

Claims (3)

A top plate portion, and a skirt-like side wall that descends from the periphery of the top plate portion, and an inner ring that extends downward in a substantially vertical direction and is inserted inside the container mouth wall, and a container mouth portion. In the plastic cap formed with the outer ring that adheres to the outer surface of the wall,
The inner ring inner portion of the top plate portion is composed of a thin annular region formed radially inward from a base portion of the inner ring, and a thick circular region formed inside the thin annular region, The thin-walled annular region is formed to be the thinnest in the entire region of the top plate portion, and a ring-shaped convex portion is formed at the boundary between the thin-walled annular region and the thick-walled circular region. . The plastic cap according to claim 1, wherein the ring-shaped convex portion has a height of 3.0 to 4.0 mm and a width of 1.0 to 2.0 mm. The thin annular region has a thickness of 0.5 to 1.1 mm and a width of 0.5 to 5.0 mm, and the thick circular region has a thickness of 1.0 to 1.8 mm. The plastic cap according to claim 1 or 2.

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