JP2004352261A - Plastic cap having superior inner pressure resistance and label stickability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic cap, which forms a sealing structure by holding the wall of a container mouth between an inner ring and an outer ring both formed on the inner surface of a top board, and effectively suppresses the breakage of sealing due to the inner pressure of the container and improves label stickability on the outer surface of the top board of the cap. <P>SOLUTION: The cap has the top board and a skirtlike side wall extending downward from the circumferential edge of the top board. The inner ring, which is inserted inside the container mouth wall, and the outer ring, which is firmly stuck on the outer surface of the container mouth wall, are formed on the inner surface of the top board. The inside part of the inner ring of the top board comprises a thin-walled annular area 30 extending radially inward from the base of the inner ring, a thick-walled circular area 32 formed inside the thin-walled annular area 30 in the radial direction, and a medium-walled annular area 34 formed at the boundary between the small wall thickness annular area 30 and the thick-walled circular area 32. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a plastic cap, and more particularly, to a plastic cap applied to a container for containing a high internal pressure liquid such as carbonated beverage.
[0002]
[Prior art]
A so-called linerless plastic cap is known, and such a linerless cap has an inner ring and an outer ring formed on the inner surface of a top plate portion. That is, with the cap closed, the upper end of the container mouth wall enters between the inner ring and the outer ring, and the seal is formed by holding the upper end of the container mouth wall therebetween. Structure.
[0003]
By the way, the above-mentioned linerless plastic cap has a problem that when applied to a container containing a content liquid such as carbonated beverage, the seal is easily broken. That is, in a container containing such a content liquid, since the pressure in the container is high, the cap swells in a dome shape (dome deformation) due to the internal pressure, and at the same time, the inner ring and the outer ring are deformed, and the inner ring is deformed. Also, there is a problem that the adhesion between the outer ring and the upper end portion of the container opening inserted therebetween is impaired, and as a result, the seal is broken.
[0004]
In order to solve such a problem, the present applicant has previously made a plastic cap (hereinafter, referred to as a plastic cap) in which the outer ring is inclined inward in the radial direction and a thin portion having an appropriate width is formed at the base of the inner ring of the top plate. A synthetic resin container lid) has been proposed (see Patent Document 1).
[0005]
[Patent Document 1]
JP-A-2000-109105 (FIGS. 2 to 6)
[0006]
That is, the above-mentioned prior art cap forms a seal particularly by the close contact between the outer ring and the container mouth wall, and actively causes the dome deformation of the cap due to the internal pressure of the container from the base of the inner ring, thereby providing a seal. This is intended to prevent the seal from being broken by alleviating the stress concentration on the close contact portion between the outer ring and the container opening wall forming the above.
[0007]
[Problems to be solved by the invention]
However, the above-mentioned prior art caps are excellent in internal pressure resistance and have the advantage of effectively suppressing seal breakage due to the container internal pressure, but have the disadvantage of poor label sticking properties. That is, a label such as a prize display is often attached to the outer surface of the top plate portion of the cap attached to the container containing the contents such as carbonated beverages, but the label is attached due to the dome deformation of the cap top plate portion. Or the inconvenience that the attached label comes off easily. In particular, when the temperature inside the container is 40 ° C. or higher, the pressure inside the container rises remarkably, and the deformation of the dome increases.
[0008]
Accordingly, an object of the present invention is to provide 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 a top plate to form a seal structure, in which seal breakage due to container internal pressure is effectively prevented. An object of the present invention is to provide a plastic cap that is suppressed and has improved label sticking properties on the outer surface of the top plate portion of the cap.
[0009]
[Means for Solving the Problems]
According to the present invention, a top plate portion, a skirt-like side wall descended from the periphery of the top plate portion, an inner ring inserted inside the container mouth wall, and an outer surface of the container mouth wall are provided on the inner surface of the top plate portion. In the plastic cap on which the outer ring and the
The inner ring inner portion of the top plate portion has a thin annular region formed radially inward from a base portion of the inner ring, a circular thick region located inside the thin annular region, and the thin annular region. A plastic cap is provided, which comprises a middle annular region formed between the circular thick region and the circular thick region.
[0010]
In the present invention,
1. 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 medium annular region has a thickness of 1.0 to 1.8 mm, 0.8 to 2.5 mm, wherein the thick circular region has a thickness of 1.6 to 3.0 mm;
2. The outer ring has an inner peripheral surface extending inclining toward the inner surface side from the base portion toward the tip, and the inner surface of the top plate portion has a position between the inner ring and the outer ring, A ring-shaped small projection that can be in contact with a corner between the upper end of the container mouth and the outer surface is formed,
Is preferred.
[0011]
In the present invention, the thin annular region formed at the base portion of the inner ring of the top plate portion is the starting point of dome deformation, and dome deformation is generated from this portion. At the same time, the adhesion between the outer ring and the upper end portion of the container opening is not impaired, and at the same time, between the thin annular region and the thick circular region (that is, inside the thin annular region), there is a middle thickness between the two regions. Since the thick annular region is formed, the dome deformation is appropriately suppressed by the middle annular region and the thick circular region. Therefore, it is possible to effectively avoid the deterioration of the label sticking property due to the top plate portion of the cap bulging more than necessary, to reliably perform the label sticking, and also to effectively avoid the disadvantage that the attached label is easily peeled off. it can.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described 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 a main part of the cap of FIG. 1 together with a container mouth.
[0013]
Referring to FIGS. 1 to 3, this cap comprises a top plate 1 and a skirt-like side wall 2 hanging from a peripheral edge of the top plate 1. An opening history indicating 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 and extends downward at a distance from the skirt-shaped side wall 2. An outer ring having a shorter height than the inner ring is formed outside the inner ring 5. 7 are provided. A small peripheral projection 9 is formed in a portion between the inner ring 5 and the outer ring 7.
[0015]
A screw 10 is formed on the inner surface of the skirt-shaped side wall 2, and the screw 10 engages with a screw 51 formed on the outer surface of the container mouth wall 50. That is, the cap is rotated by turning the skirt-shaped 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 opening wall 50, thereby forming the container opening. 50 is attached. A cutout is formed in the screw 10 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. Further, an axial groove 10a may be provided at the notch. Gas can be discharged more quickly by the axial groove 10a.
[0016]
A knurl 12 for preventing slippage 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 flap piece 14 known per se 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 elevation of the TE band 2 is restricted. On the other hand, the skirt-shaped side wall 2 rotates in the opening direction and rises. Accordingly, the bridge 3 connecting the lower end of the skirt-shaped side wall 2 and the TE band is broken, and the TE band 5 is detached from the cap. Thus, the fact that the TE band 5 is detached from the cap makes it possible to recognize the fact that the cap was once opened or the seal was broken.
[0018]
In particular, as clearly shown in FIG. 3, when 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, The small annular projection 9 contacts the corner between the upper end surface 50a and the outer surface 50b. That is, the seal inside the container is formed by the outer ring 7 and the small annular projection 9 or by the three-point holding of the inner ring 5, the outer ring 7 and the small annular projection 9.
[0019]
In the present invention, the inner ring 5 descends substantially in the vertical direction from the inner surface of the top plate portion 1 or has a convex portion formed on the outer peripheral surface, and is in close contact with the inner surface of the container. The outer ring 7 is inclined inward toward its lower end, and is formed so as to bite into the outer surface of the container mouth wall 50. Further, the small annular projection 9 is formed at the base of the outer ring 7 and is in close contact with the corner between the upper end surface 50a and the outer surface 50b of the container mouth wall 50. Thus, the outer ring 7 and the small annular projection 9 form a main seal. For this reason, excellent pressure resistance is ensured even for containers whose internal pressure is increased by filling with carbonated beverages and the like. That is, when the 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 the deformation of the inner ring 5 due to the dome deformation (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 if the outer ring 7 is slightly deformed.
[0020]
In the present invention, a thin annular region 30 is formed radially inward from the base portion of the inner ring 5 on the inner side of the inner ring 5 of the top plate portion 1, and a thick circular portion is formed on the center portion of the top plate portion 1. It is important that a region 32 is formed, and that between the thin circular region 30 and the thick circular region 32, a medium circular region 34 having an intermediate thickness between these regions 30 and 32 is formed. .
[0021]
That is, the pressure resistance of the cap is further improved by the thin annular region 30 formed at the base of the inner ring 5. For example, when the main seal is formed only by the outer ring 7, when the inside of the container filled with the carbonated beverage is heated to a high temperature of 40 ° C. or more, the internal pressure of the container is significantly increased. However, a large stress is generated in the outer ring 7 which is in close contact with the container mouth wall 50, the deformation is remarkable, and the seal is broken. However, by forming the thin annular region 30 as described above, the top plate 1 is dome-deformed (expanded outward) from the base of the inner ring 5 as a starting point. In this case, the stress concentration on the outer ring 7 is particularly suppressed, and even in such a case, it is possible to effectively prevent the breakage of the seal, and it is possible to secure extremely excellent internal pressure resistance.
[0022]
Further, the thick circular region 32 and the medium annular region 34 formed inside the thin annular region 30 allow the dome deformation of the top plate portion 1 to be adjusted to an appropriate level, thereby achieving the above-described superior characteristics. Thus, the label sticking property can be improved without impairing the internal pressure resistance. In other words, the cooperative action of the thick circular region 32 and the middle annular region 34 suppresses the extreme dome deformation of the top plate 1 even when the container internal pressure is significantly increased. It is kept close to flat. As a result, the label can be easily and reliably attached to the outer surface of the top plate 1, and the attached label does not peel off. For example, when the thick circular region 32 and the middle annular region 34 are not formed, the degree of dome deformation of the top plate portion 1 is large (the top plate portion 1 swells outward greatly). It is in a state of being floated from the outer surface, making it difficult to attach, or even if it can be attached, it is easily peeled off because the peripheral portion is floating.
[0023]
In the present invention, it is important to adjust the degree of dome deformation by the circular region 32 and the middle annular region 34. For example, only the thickness adjustment of the thin annular region 30 is performed without forming the middle annular region 34. In this case, even if the label sticking property can be improved, the dome deformation starting from the thin annular region 30 (that is, the base portion of the inner ring 5) is suppressed, so that the stress concentration on the outer ring 7 cannot be reduced. This is because the internal pressure resistance is reduced, and it is difficult to prevent the seal from being broken by the internal pressure of the container. Further, only by adjusting the thickness of the thick annular region 32, an appropriate dome deformation cannot be generated, and either the internal pressure resistance or the label sticking property becomes unsatisfactory.
[0024]
Therefore, in the present invention, the width and thickness of the above-described medium-walled annular region 34 and thin-walled annular portion 30 and the thickness and the like of the thick-walled circular portion 32 can ensure label sticking properties, but are not so large as to impair internal pressure resistance. Dome deformation should be set. For example, although it depends on the size of the cap, usually, the thin annular region 30 has a thickness of 0.5 to 1.0 mm and a width of 0.5 to 5.0 mm. 34 preferably has a thickness of 1.0 to 1.8 mm and a width of 0.8 to 2.5 mm, and the thick circular region 32 has a thickness of 1.6 to 3.0 mm. It is preferable to have Of course, the thickness of each region satisfies the relationship of the thin annular region 30 <the middle annular region 34 <the thick circular region 32.
[0025]
The above-described cap of the present invention is manufactured by injection using various plastics, for example, low-, medium- or high-density polyethylene, linear low-density polyethylene, polypropylene, thermoplastic polyester, polyamide, styrene resin, and ΔS resin. It can be manufactured by integral molding such as molding and compression molding.
[0026]
【Example】
Example 1
A cap having the shape shown in FIG. 1 was prepared by compression molding using high-density polyethylene. The width and thickness of each region of the top plate of the cap are as follows.
Top plate outer diameter: 30mm
Thin annular region;
Width: 1.6mm
Thickness: 0.8mm
Medium annular region;
Width: 1.8mm
Thickness: 1.4mm
Thick circular area;
Diameter: 13mm
Thickness: 2.2mm
[0027]
The above cap was attached to a 500 ml PET bottle filled with carbonated beverage, and the amount of doming measured at a temperature of 40 ° C. was 1.60 mm. (Note that the doming amount is the height difference from the state where there is no dome deformation at the center of the cap top plate.)
[0028]
When a circular label having a diameter of 17.7 mm coated with an adhesive was attached to the outer surface of the top plate portion of the cap, the entire label was stuck to the cap top plate portion in close contact.
[0029]
Comparative Example 1
Except that no medium annular region was formed and the thick circular region extended to the portion of the medium annular region, the same cap as in Example 1 was created, and the amount of doming was reduced in the same manner as in Example 1. The measured value was 2.00 mm, and extremely large dome deformation occurred as compared with Example 1.
[0030]
Furthermore, when a circular label was attached to the outer surface of the top plate portion of the cap as in Example 1, the peripheral portion of the label floated, and the attached label was immediately peeled off.
[0031]
【The invention's effect】
The plastic cap of the present invention is filled with beverages such as carbonated beverages, and even when applied to a container having a high internal pressure, it is possible to prevent a seal from being broken by a further increase in internal pressure due to a rise in temperature, and at the same time, to apply a label to 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.
FIG. 2 is a bottom view of the cap of FIG. 1;
FIG. 3 is an enlarged sectional view showing a main part of the cap of FIG. 1 together with a container mouth.
[Explanation of symbols]
1: Top plate part 2: Skirt side wall 5: Inner ring 7: Outer ring 9: Small annular projection 30: Thin annular area 32: Thick circular area 34: Medium annular area 50: Container mouth wall

Claims (3)

A top plate portion, a skirt-shaped side wall descended from the periphery of the top plate portion, an inner ring inserted into the inside of the container mouth wall, and an outer ring closely attached to the outer surface of the container mouth wall on the inner surface of the top plate portion. In the plastic cap where is formed,
An inner ring inner portion of the top plate portion is a thin annular region formed radially inward from a base portion of the inner ring, a circular thick region located inside the thin annular region, and the thin annular region. A plastic cap comprising: a middle annular region formed between the circular thick region; 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 medium annular region has a thickness of 1.0 to 1.8 mm, The plastic cap according to claim 1, having a width of 0.8 to 2.5 mm, and wherein the thick circular region has a thickness of 1.6 to 3.0 mm. The outer ring has an inner peripheral surface that extends inclining toward the inner surface side from the base portion toward the tip, and the inner surface of the top plate portion has a position between the inner ring and the outer ring, The plastic cap according to claim 1 or 2, wherein a small ring-shaped projection is formed which can abut on a corner between the upper end of the container mouth and the outer surface.

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