JP4533597B2 - Plastic cap with excellent internal pressure resistance and label stickability - 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 remarkably increased, and the dome deformation is increased.
[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, a top plate portion and a skirt-like side wall descending from the periphery of the top plate portion are provided, and on the inner surface of the top plate portion, an inner ring inserted inside the container mouth wall, and an outer surface of the container mouth wall In a plastic cap formed with an outer ring that adheres closely to
An inner ring inner portion of the top plate portion includes a thin annular region formed radially inward from a base portion of the inner ring, a thick circular region located inside the thin annular region, and the thin annular region together consist the formed medium thickness annular region between the thick circular area,
The outer surface of the top plate portion is formed flush with each other,
The portions corresponding to the thin annular region, the middle annular region and the thick circular region each include a portion having a flat inner surface,
A plastic cap is provided in which the thin annular region is thinner than the inner annular region, and the inner annular region is thinner than the thick circular 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 intermediate annular region has a thickness of 1.0 to 1.8 mm and 0 A thick circular region having a thickness of 1.6 to 3.0 mm,
2. The outer ring has an inner peripheral surface that is inclined and extended toward the inner surface side from the base portion toward the tip, and the inner surface of the top plate portion is at a position between the inner ring and the outer ring, A ring-shaped small protrusion is formed that can come into contact with the corner between the upper end of the container mouth and the outer surface;
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, between the thin annular region and the thick circular region (that is, inside the thin annular region), there is an intermediate thickness between both regions. Since the meat annular region is formed, the dome deformation is moderately suppressed by the middle annular region and the thick circular region. 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 cross-sectional view showing the main part of the cap of FIG. 1 together with the container mouth part.
[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 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 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, a thin annular region 30 is formed on the inner side of the inner ring 5 of the top plate portion 1 from the base portion of the inner ring 5 to the inner side in the radial direction, and a thick circular shape is formed in the central portion of the top plate portion 1. It is important that a region 32 is formed, and that a middle annular region 34 having a thickness intermediate between these regions 30 and 32 is formed between the thin annular region 30 and the thick circular region 32. .
[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]
In addition, the thick circular region 32 and the middle annular region 34 formed inside the thin annular region 30 can be adjusted to an appropriate degree of dome deformation of the top plate portion 1, thereby achieving the above-described excellent performance. Thus, 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 middle annular region 34, even when the internal pressure of the container is significantly increased, extreme dome deformation of the top plate portion 1 is suppressed. It is held close to flat. 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 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 greatly outward), so that the peripheral portion of the label is the top plate portion 1. Even if it can be stuck, it will be easily peeled off because the periphery is floating.
[0023]
In the present invention, it is important to adjust the degree of dome deformation by the thick circular region 32 and the inner annular region 34. For example, the inner annular region 34 is not formed, and the thickness of the thin annular region 30 is increased. 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. Further, only by adjusting the thickness of the thick circular region 32, an appropriate dome deformation cannot be generated, and either the internal pressure resistance or the label sticking property becomes unsatisfactory.
Therefore, in the present invention, the width and thickness of the inner annular region 34 and the thin annular region 30, the thickness of the thick circular region 32, and the like described above can ensure label sticking properties, but do not impair internal pressure resistance. The dome deformation is set to occur . For example, although the specific numerical value varies depending on the size of the cap , the thin annular region 30 has a thickness of 0.5 to 1.1 mm and a width of 0.5 to 5.0 mm. The thick annular region 34 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. Have Of course, the thickness of each region satisfies the relationship of the thin annular region 30 <the intermediate annular region 34 <the thick circular region 32.
[0025]
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.
[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 portion of the cap are as follows.
Top plate outer diameter: 30mm
Thin annular region;
Width: 1.6mm
Thickness: 0.8mm
Fillet annular area;
Width: 1.8mm
Thickness: 1.4mm
Thick circular area;
Diameter: 13mm
Thickness: 2.2mm
[0027]
The cap was attached to a 500 ml PET bottle filled with a carbonated beverage, and the doming amount measured at a temperature of 40 ° C. was 1.60 mm. (The doming amount is a difference in height from the state where there is no dome deformation at the center of the cap top plate.)
[0028]
When a 17.7 mm diameter circular label coated with an adhesive was affixed to the outer surface of the top plate portion of the cap, the entire label was closely adhered to the cap top plate portion and was stably adhered.
[0029]
Comparative Example 1
The cap is made exactly the same as in Example 1 except that the inner annular region is not formed at all and the thick circular region extends to the inner annular region, and the doming amount is set in the same manner as in Example 1. As a result of measurement, it was 2.00 mm, and an extremely large dome deformation was generated as compared with Example 1.
[0030]
Furthermore, when the circular label was affixed to the outer surface of the top plate part of the cap as in Example 1, the peripheral edge of the label floated, and the affixed label was immediately peeled off.
[0031]
【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.
[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: Medium annular area 50: Container mouth wall

Claims (3)

A top plate part, and a skirt-like side wall that descends from the periphery of the top plate part, and an inner ring that is inserted inside the container mouth wall on the inner surface of the top plate part, and an outer ring that is in close contact with the outer surface of the container mouth wall In the plastic cap in which is formed,
An inner ring inner portion of the top plate portion includes a thin annular region formed radially inward from a base portion of the inner ring, a thick circular region located inside the thin annular region, and the thin annular region together consist the formed medium thickness annular region between the thick circular area,
The outer surface of the top plate portion is formed flush with each other,
The portions corresponding to the thin annular region, the middle annular region and the thick circular region each include a portion having a flat inner surface,
The plastic cap , wherein the thin annular region is thinner than the inner annular region, and the inner annular region is thinner than the thick circular 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 intermediate annular region has a thickness of 1.0 to 1.8 mm and 0 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 is inclined and extended toward the inner surface side from the base portion toward the tip, and the inner surface of the top plate portion is at a position between the inner ring and the outer ring, The plastic cap according to claim 1 or 2, wherein a ring-shaped small protrusion capable of coming into contact with a corner portion between an upper end and an outer surface of the container mouth portion is formed.

Images