Note: Descriptions are shown in the official language in which they were submitted.
CA 02528254 2008-02-07
DESCRIPTION
SYNTHETIC RESIN CAP, CLOSING DEVICE, AND
BEVERAGE-FILLED CONTAINER
TECHNICAL FIELD
This invention relates to a synthetic resin cap that is attached to a
container
opening and seals the container opening, a closing device using the synthetic
resin
cap, and a container-filled beverage.
BACKGROUND ART OF THE INVENTION
A linerless cap, which gives a seal function to a cap body, is one type of a
synthetic resin cap.
A cap including on its top plate an inner seal projection that fits into the
container opening is used as this type of linerless cap.
In conventional synthetic resin caps there is a problem in that, at the time
of
attaching to the container opening, the hermeticity deteriorates when the
winding
tightness is insufficient, and the disconnecting torque becomes too great when
the
winding tightness is excessive.
For this reason, there is a demand for a technique for reliably obtaining the
appropriate hermeticity and disconnecting torque.
DISCLOSURE OF INVENTION
The present invention has been realized in view of the circumstances
described above, and aims to provide a synthetic resin cap that may reliably
obtain the
appropriate hermeticity and disconnecting torque.
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The synthetic resin cap of this invention is characterized in that a circular
opening edge seal projection that contacts an opening edge of a container
opening is
provided on the inner face of a top plate, and, at the time of attaching the
synthetic.
resin cap to the container opening, the opening edge seal projection is made
able to
bend and be deformed in the expanding radial direction until it contacts a cap
body; a
positioning protrusion is provided on the top plate, and contacts the opening
edge
when the opening edge seal projection has bend and deformed until contacting
the cap
body.
The positioning protrusion may preferably be integrated with the inner seal
projection.
The opening seal projection may be constituted from an erect cylindrical
section extending downward from the top plate, and an expanding cylindrical
section
spreads in a skirt-like shape from the erect cylindrical section.
In accordance with an aspect of the present invention, there is provided a
synthetic resin cap comprising: a cap body having a top plate and a
cylindrical section
extending downward from a periphery of the top plate; a circular inner seal
projection
formed on an inner surface of the top plate and fits into a container opening;
and a
circular opening edge seal projection formed on the inner surface of the top
plate and
contacts an opening edge of the container opening, wherein the opening edge
seal
projection bends and deforms in an expanding radial direction until contacting
the cap
body at the time of attaching the synthetic resin cap to the container
opening, wherein a
positioning protrusion is provided on the top plate that contacts the opening
edge when
the opening edge seal projection bend and deformed until contacting the cap
body,
wherein the positioning protrusion is integrated with the inner seal
projection, and
wherein the positioning protrusion is separated from the opening edge seal
projection.
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In accordance with another aspect of the present invention, there is provided
a
closing device comprising a container and a synthetic resin cap that is
attached to an
opening of the container, wherein the synthetic resin cap has a cap body
having a top
plate and a cylindrical section extending downward from the periphery of the
top
plate, a circular inner seal projection formed on an inner surface of the top
plate and
fits into a container opening, and a circular opening edge seal projection
formed on
the inner surface of the top plate and contacts an opening edge of the
container
opening, wherein the opening edge seal projection bends and deforms in an
expanding
radial direction until contacting the cap body at the time of attaching the
synthetic
resin cap to the container opening, wherein a positioning protrusion is
provided on the
top plate and contacts the opening edge when the opening edge seal projection
bend
and deformed until contacting the cap body, wherein the positioning protrusion
is
integrated with the inner seal projection, and wherein the positioning
protrusion is
separated from the opening edge seal projection.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a partial cross-sectional view showing an embodiment of a closing
device according to this invention.
FIG. 2 is an enlarged cross-sectional view showing part of the synthetic resin
cap shown in FIG. 1.
FIG. 3 is a step diagram showing a step of attaching the synthetic resin cap
shown in FIG. 1 to a container opening.
FIG. 4 is a step diagram showing a state in which the synthetic resin cap of
FIG. 1 is attached to the container opening.
BEST MODE FOR CARRYING OUT THE INVENTION
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FIG. I and FIG. 2 show an embodiment of a closing device of this invention,
the closing device shown here including a container 21, and a synthetic resin
cap 1
that is attached to an opening 20 of the container 21.
The container 21 is made of a synthetic resin such as polyethylene
terephthalate (PET), glass, or the like, a threaded section 22 that is formed
around the
outer periphery of the container opening 20, and an expanding step section 23
that is
formed below the threaded section 22. An opening edge 20b of the container
opening 20 is provided flatly so as to run along a substantially horizontal
face.
The synthetic resin cap 1 includes a cap body 4 having the disk-shaped top
plate 2 and a cylindrical section 3 extending downward from the periphery of
the top
plate2, a circular inner seal projection 12 which fits into the container
opening 20
projecting downward provided on an inner surface of the top plate 2, and a
circular
opening edge seal projection 13, which contacts the opening edge 20b
(particularly
outer peripheral section 20c thereof) of the container opening 20 projecting
downward provided on an inner surface of the top plate 2.
The cylindrical section 3 of the cap body 4 is divided by a horizontal score 6
(weakening line) into a main section 8 above the horizontal score 6, and a
tamper
evidence ring section 9 (TE ring section), which is connected to the bottom
edge of
the main section 8 by bridges 7.
A threaded section 10 engaging with the threaded section 22 of the container
opening 20 is formed on the inner face of the main section 8.
Tabs 11 are provided on the inner face of the TE ring section 9. Tabs 11 are a
plurality of thin plate-like clipping means for preventing the movement of the
TE
ring section 9 by clipping with the container 21 when the cap I is
disconnected.
The cap I is made of a synthetic resin material such as high density
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polyethylene or polypropylene.
The inner seal projection 12 contacts an inner peripheral surface 20a of the
container opening 20 when fitted into the container opening 20.
Preferably, the inner seal projection 12 may gradually increase in diameter as
it extends downward, so that the outer diameter of a maximum outer diameter
section
12a is greater than the inner diameter of the container opening 20.
The inner seal projection 12 may preferably be formed so that it may
elastically deformable in the compressing radial direction so as to be fitted
into the
container opening 20.
That is, as shown by the alternate long and short dash line in FIG. 2, the
inner
seal projection 12 may be constituted so that it may elastically bend and
deform in
the compressing radial direction (the direction in which a tip 12c moves
inward) at a
base section 12b.
The protruding length of the inner seal projection 12 is preferably from 1 to
5
mm (more preferably from 2 to 4 mm).
The thickness of the inner seal projection 12 is preferably from 0.5 to 2 mm
(more preferably from 0.5 to 1 mm).
The gradient angle of the outer surface of the inner seal projection 12 with
respect to the vertical direction (the direction perpendicular to the top
plate 2) is
preferably from 5 to 30 (more preferably from 10 to 20 ).
The height position of the maximum outer diameter section 12a is preferably
set so that the distance between the maximum outer diameter section 12a and
the top
plate 2 is 4 mm or less (more preferably 3 mm or less).
The outer diameter of the maximum outer diameter section 12a is preferably
from 21.74 mm to 23.74 mm (more preferably from 21.94 mm to 22.94 mm).
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The difference between the outer diameter of the maximum outer diameter
section 12a and the inner diameter of the container opening 20 is preferably 1
mm or
less (more preferably from 0.1 mm to 0.6 mm).
The opening edge seal projection 13 sealing the opening edge 20b of the
container opening 20 (particularly the outer peripheral section 20c) is formed
on the
outer side of the diameter direction than the inner seal projection 12. The
opening
edge seal projection 13 has an erect cylindrical section 13a extending
substantially
vertically downward from the inner face of the top plate 2, and a skirt-like
expanding
cylindrical section 13b widening in diameter along with extending downward
from
the bottom edge of the erect cylindrical section 13a.
The projection length of the opening edge seal projection 13 is preferably
from 1 mm to 4 mm (more preferably from 1.5 mm to 3 mm).
The length of the erect cylindrical section 13a is preferably from 0.5 mm to 3
mm (more preferably from 1 mm to 2 mm), and thickness thereof is preferably
from
0.1 nun to 1 mm (more preferably from 0.2 mm to 0.5 mm).
The length of the expanding cylindrical section 13b is preferably from 0.5
mm to 3 mm (more preferably from 1 mm to 2 mm), and thickness thereof is
preferably set greater than the thickness of the erect cylindrical section
13a, more
specifically, from 0.2 mm to 1.5 mm (more preferably from 0.4 mm to 1 mm).
The gradient angle of the expanding cylindrical section 13b with respect to
the vertical direction is preferably from 20 to 60 .
The opening edge seal projection 13 is capable of bending and deforming in
the expanding radial direction at a base section 13c of the erect cylindrical
section
13 a.
The inner diameter of the erect cylindrical section 13a is set smaller than
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outer diameter of the container opening 20.
The diameter of a bottom edge 13d of the expanding cylindrical section 13b is
preferably set larger than the outer diameter of the container opening 20.
A thin section 2b is thinner than the outer periphery section 2a, and is
formed
in the central section of the top plate 2. The thin section 2b is provided
inner than the
base section 12b of the inner seal projection 12. The thin section 2b is
preferably
circular in shape.
The thickness of the thin section 2b is preferably from 0.5 mm to 2.0 mm
(more preferably from 1.0 mm to 1.5 mm).
The height of a step 2c between the outer periphery section 2a and the thin
section 2b is preferably from 0.1 mm to 1.0 (more preferably from 0.2 mm to
0.8
mm).
An auxiliary wall section 14 is provided at a corner 15 on the inner surface
of
the connecting section between the top plate 2 and the cylindrical section 3,
and
tapers from top to bottom so as to fill up the corner 15.
Since the auxiliary wall section 14 increases the rigidity of the connecting
section between the top plate 2 and the cylindrical section 3, preventing the
top plate
2 from expanding and deforming when the pressure inside the container 21 is
increased, the height and width of the auxiliary wall section 14 is preferably
between
0.2 mm and 2 mm (more preferably between 0.5 mm and 1.8 mm).
The auxiliary wall section 14 is made of the same material as the cap body 4,
and is preferably integrated with the cap body 4.
In the cap 1 of this embodiment, a positioning protrusion 16 contacting the
opening edge 20b of the container opening 20 is provided on the top plate 2.
The positioning protrusion 16 is substantially rectangular in cross-section
and
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protrudes downward in order to keep the distance between the top plate 2 and
the
opening edge 20b substantially constant and to keep the wind tightening angle
substantially constant when attaching the cap.
The positioning protrusion 16 is integrated with the inner seal projection 12
on the outer surface side of the inner seal projection.
The positioning protrusion 16 is provided at a position so that bottom face
16a thereof contacts the opening edge 20b as attaching the cap 1 to the
container
opening 20.
The positioning protrusion 16 may be formed in a continuous circular shape
in the circumferential direction, or in a non-continuous circular shape
including a
plurality of island-like projections that are arranged in the circumferential
direction.
The height A of the positioning protrusion 16 is preferably from 0.2 nun to
1.5 mm (more preferably from 0.5 mm to 1 mm).
When the height A is shorter than this range, the disconnecting torque is
liable to become excessive; when the height A is higher than this range, the
hermeticity is liable to decrease.
The width B of the positioning protrusion 16 is preferably from 0.5 mm to 1.5
mm (more preferably from 0.7 nun to 1.3 mm).
Subsequently, the operation of the cap I when it is attached to the container
opening 20 will be explained with reference to FIGS. 3 and 4.
When the cap 1 is wound and tightened around the container opening 20, the
inner seal projection 12 fits into the container opening 20 and contacts the
inner
peripheral surface 20a of the container opening 20 with no gap therebetween.
When the inner seal projection 12 fits into the container opening 20, the
inner
seal projection 12 elastically bends and deforms at the base section 12b in
the
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compressing radial direction (the direction in which the tip 12c moves inward)
(see
FIG. 3).
As a consequence, the outer diameter of the inner seal projection 12
decreases,
enabling it to fit into the container opening 20.
After having been fitted into the container opening 20, the inner seal
projection 12 has elastically deformed in the compressing radial direction,
whereby
its elastic restoring force applies a pressing force to the container opening
20 in the
expanding radial direction.
As the cap 1 is rotated, the outer peripheral section 20c of the opening edge
20b of the container opening 20 contacts the inner surface of the expanding
cylindrical section 13b of the opening edge seal projection 13, applying an
upward
force against it (see FIG. 3).
As a result of the application of the upward force of the container opening 20
against the expanding cylindrical section 13b, a force in the expanding radial
direction is applied against the opening edge seal projection 13, whereby the
opening
edge seal projection 13 bends and deforms at the base 13c in the expanding
radial
direction, and its tip side moves outward.
As shown in FIG. 4, when the cap 1 is further rotated, the container opening
20 causes the opening edge seal projection 13 to bend and deform further in
the
expanding radial direction, and a tip 13e contacts the cap body 4 (the
auxiliary wall
section 14 in the example shown in FIG. 4).
In this state, the outer peripheral section 20c of the opening edge 20b
applies
a diagonally upward pressing force against the erect cylindrical section 13a,
and in
addition, the auxiliary wall section 14 applies a diagonally downward
resistant force
against the expanding cylindrical section 13b, whereby the opening edge seal
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projection 13 slightly bends and deforms in the midsection of longitudinal
direction
so as to jut outward.
Consequently, the opening edge seal projection 13 bends and deforms
outwardly at the base section 13c and bends and deforms outwardly also at the
midsection of the longitudinal direction.
Therefore, the elastic restoring force pushes the opening edge seal projection
13 against the opening edge 20b (particularly the outer peripheral section
20c) so that
the opening edge seal projection 13 contacts the opening edge 20b
(particularly the
outer peripheral section 20c) without a gap, thereby sealing the container
opening 20.
At this time, since the opening edge seal projection 13 does not contact the
entire opening edge 20b but only a narrow area including the outer peripheral
section
20c, the force applied against the opening edge 20b by the opening edge seal
projection 13 is concentrated near the outer peripheral section 20c.
In the state shown in FIG. 4, the opening edge 20b of the container opening
20 is contacting the bottom surface 16a of the positioning protrusion 16.
This positions the height of the cap I with respect to the opening edge 20b,
and obtains a predetermined distance between the top plate 2 and the opening
edge
20b.
Consequently, the deformation amount of the opening edge seal projection 13
reaches a predetermined value, and the pressing force of the opening edge seal
projection 13 against the opening edge 20b reaches a predetermined value.
By attaching the cap I to the container opening 20 by the steps described
above, the container 21 is hermetically sealed. When the cap 1, which has been
attached to the container opening 20, is
rotated in the disconnecting direction, the tabs 11 that are provided on the
inner
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surface of the TE ring section 9 clip with the bottom edge of the expanding
step
section 23 of the container opening 20, making the main section 8 of the cap
body 4
rise as the cap 1 is rotated and stopping the TE ring section 9 from moving
upward.
Consequently, an expanding force acts on the plurality of narrow bridges 7
that are
connecting the cap main section 8 to the TE ring section 9, breaking the
bridges 7,
cutting away the TE ring section 9 from the main section 8, and disconnecting
the cap
In the cap 1 of this embodiment, since the positioning protrusion 16 is
provided on the top plate 2 and contacts the opening edge 20b when the opening
edge
seal projection 13 has bent and deformed until contacting the cap body 4, at
the time
of attaching the cap, a predetermined distance between the top plate 2 and the
opening
edge 20b can be ensured, and the pressing force of the opening edge seal
projection
13 against the opening edge 20b can be made sufficient.
Therefore, sufficient sealing capability can be achieved.
Furthermore, since a predetermined distance can be obtained between the top
plate 2 and the opening edge 20b, a predetermined wind tightening angle can be
ensured when attaching the cap.
Therefore, the disconnecting torque can be set to an appropriate value.
Incidentally, the clipping means of the tamper evidence ring section 9 are not
limited to the tabs 11 in the embodiment described above, it being acceptable
to use
tabs including wings and beads, as disclosed in Japanese Patent Application
No. H08-
46445 already applied for by the present applicant, or clipping means that
combine
clipping claws on the container side and clipping protrusions on the tamper
evidence
ring side, as disclosed in Japanese Patent Publication Nos. 08-091401, 08-
113254, 08-
133313, 08-164958, 08-164960, 07-294714, and 07-316471.
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In this invention, the container 21 may be filled with a beverage such as
fruit
juice, tea, coffee, and the like, so that by attaching the cap 1 to the
container opening
20 it is possible to obtain a container-filled beverage.
INDUSTRIAL APPLICABILITY
As described above, the synthetic resin cap of this invention has the
positioning protrusion contacting the opening edge on the top plate, so that
at the
time of attaching the cap, a predetermined distance may be obtained between
the top
plate and the opening edge, and a predetermined pressing force may be applied
against the opening edge by the opening edge seal projection, obtaining
sufficient
sealing capability.
Furthermore, since a predetermined distance can be obtained between the top
plate and the opening edge, the wind tightening angle when attaching the cap
can be
set at a predetermined value, and the disconnecting torque can be set to an
appropriate value.
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