U.S. patent application number 11/991732 was filed with the patent office on 2009-05-14 for tamper-evident screw closure for containers and bottles, especially for plastic bottles.
Invention is credited to Oliver Hoch, Thomas Karl Zauser.
Application Number | 20090120936 11/991732 |
Document ID | / |
Family ID | 35457504 |
Filed Date | 2009-05-14 |
United States Patent
Application |
20090120936 |
Kind Code |
A1 |
Zauser; Thomas Karl ; et
al. |
May 14, 2009 |
Tamper-Evident Screw Closure for Containers and Bottles, Especially
for Plastic Bottles
Abstract
A plastic tamper-evident screw closure is disclosed for
containers and bottles. An exemplary tamper-evident screw closure
includes a screw cap, which has a cylindrical jacket with an
internal thread, and an annular tamper-evident strip which is
connected to a free edge of the jacket by breaking webs or the like
and is equipped with locking elements. The tamper-evident strip can
have a smaller outside diameter than the jacket of the screw cap.
The locking elements can be configured as undercut regions in the
tamper-evident strip which in each case run between two adjacent
breaking webs as a ring segment, and extend from a cylindrical
inner wall to an outer wall of the tamper-evident strip.
Inventors: |
Zauser; Thomas Karl;
(Bregenz, AT) ; Hoch; Oliver; (Altach,
AT) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Family ID: |
35457504 |
Appl. No.: |
11/991732 |
Filed: |
August 12, 2006 |
PCT Filed: |
August 12, 2006 |
PCT NO: |
PCT/EP2006/008008 |
371 Date: |
March 10, 2008 |
Current U.S.
Class: |
220/257.1 ;
215/217 |
Current CPC
Class: |
B65D 41/3447
20130101 |
Class at
Publication: |
220/257.1 ;
215/217 |
International
Class: |
B65D 55/06 20060101
B65D055/06; B65D 51/20 20060101 B65D051/20 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 15, 2005 |
CH |
1500/05 |
Claims
1. Tamper-evident screw closure of plastic comprising: a screw cap
which has a cylindrical jacket with an internal thread; a
ring-shaped tamper-evident strip which is connected via breakaway
webs or the like to a free edge of the jacket; and locking elements
configured for positive engagement with an abutment of a container
or bottle, wherein the tamper-evident strip has an outside diameter
which is smaller than that of the jacket of the screw cap and
wherein the locking elements are formed by bevelled undercut
regions of the tamper-evident strip which each run as a ring
segment between two adjacent breakaway webs and which extend from
an axially longer cylindrical inside wall to an axially shorter
outside wall of the tamper-evident strip.
2. Tamper-evident screw closure as claimed in claim 1, wherein the
tamper-evident strip has a wall thickness which is 40% to 80% of
the wall thickness of the cylindrical jacket of the screw cap in a
thread-free region.
3. Tamper-evident screw closure as claimed in claim 1, wherein each
beveled undercut region of the tamper-evident strip has an axial
length which is 1/3 to 2/3 of an axial length of the breakaway
webs.
4. Tamper-evident screw closure as claimed in claim 1, wherein each
undercut region with the inside wall of the tamper-evident strip
forms a largely sharp-edged transition.
5. Tamper-evident screw closure as claimed in claim 1, wherein the
breakaway webs have an axial length which is 50% to 100% of an
axial length of the outside wall of the tamper-evident strip
adjoining the undercut regions.
6. Tamper-evident screw closure as claimed in claim 1, wherein an
axial length of the breakaway webs is such that an annular gap
between the screw cap and the tamper-evident strip has a width from
roughly 0.5 mm to roughly 5 mm.
7. Tamper-evident screw closure as claimed in claim 1, wherein an
inside diameter of the tamper-evident strip measured over the
undercut regions is larger than an inside diameter of the screw cap
measured over on the internal thread sections.
8. Tamper-evident screw closure as claimed in claim 1, wherein the
undercut regions which each run as a ring segment between the
breakaway webs have a peripheral extension which corresponds to 60%
to 100% of a distance measured in a peripheral direction between
two adjacent lengthwise edges of two adjacent breakaway webs.
9. Container in combination with a tamper-evident screw closure as
claimed in claim 1.
10. Container as claimed in claim 9, comprising: a region of a neck
of the container in which the tamper-evident strip is located when
the tamper-evident screw closure has been screwed on the container,
wherein the region has a longer axial extension than that of the
tamper-evident strip.
11. Tamper-evident screw closure as claimed in claim 2, wherein
each beveled undercut region of the tamper-evident strip has an
axial length which is 1/3 to 2/3 of an axial length of the
breakaway webs.
12. Tamper-evident screw closure as claimed in claim 11, wherein
each undercut region with the inside wall of the tamper-evident
strip forms a largely sharp-edged transition.
13. Tamper-evident screw closure as claimed in claim 12, wherein
the breakaway webs have an axial length which is 50% to 100% of an
axial length of the outside wall of the tamper-evident strip
adjoining the undercut regions.
14. Tamper-evident screw closure as claims in claim 13, wherein the
axial length of the breakaway webs is such that an annular gap
between the screw cap and the tamper-evident strip has a width from
roughly 0.5 mm to roughly 5 mm.
15. Tamper-evident screw closure as claimed in claim 14, wherein an
inside diameter of the tamper-evident strip measured over the
undercut regions is larger than an inside diameter of the screw cap
measured over on the internal thread sections.
16. Tamper-evident screw closure as claimed in claim 15, wherein
the undercut regions which each run as a ring segment between the
breakaway webs have a peripheral extension which corresponds to 60%
to 100% of a distance measured in a peripheral direction between
two adjacent lengthwise edges of two adjacent breakaway webs.
17. Container in combination with a tamper-evident screw closure as
claimed in claim 16.
18. Container as claimed in claim 17, wherein the container is a
plastic bottle.
Description
[0001] The invention relates to a tamper-evident screw closure for
containers and bottles, especially for plastic bottles, as claimed
in the preamble of claim 1.
[0002] The metal caps which were used in the past for closing of
containers and bottles, so-called crown corks, for removal of which
a separate tool was necessary, are being increasingly replaced by
plastic screw closures. These plastic closures are generally
produced in an injection molding process or in a diecasting
process. Generally the plastic closures are made as so-called
tamper-evident screw closures. For this purpose the actual screw
cap of the closure is connected to a ring-shaped, tamper-evident
strip which is connected to the free edge of the jacket of the
screw cap by breakaway webs. Intactness of the connection of the
tamper-evident strip to the screw cap is designed to indicate that
the closure has not been opened since the container or bottle was
filled and sealed.
[0003] In the known version of tamper-evident screw closures,
projections protrude from the inside wall of the ring-shaped
tamper-evident strip and by a blocking interaction with the
corresponding profiling on the wall of the neck of the bottle they
provide for the tamper-evident strip not being able to follow the
rotary motion of the closure cap when the tamper-evident screw
closure is being unscrewed, but the breakaway sites are sheared
off. Generally, on the neck of the bottle there is additionally a
peripheral flange which prevents the tamper-evident strip which has
been separated from the screw cap from falling off the neck of the
bottle. When the tamper-evident screw closure is unscrewed, the
peripheral flange generally to a certain extent also provides for
the tamper-evident strip not being able to follow the axial motion
of the screw cap and the breakaway sites being additionally broken
open by the tensile loading between the screw cap and the
tamper-evident strip.
[0004] In known tamper-evident screw closures, the projections
protruding from the inside wall of the tamper-evident strip are
generally made wedge-shaped in the closing direction of rotation.
This is designed to facilitate the tamper-evident screw closure
being screwed on. For reasons of production engineering, the
protrusion of the projections over the inside wall of the
tamper-evident strip is however only relatively small. On the other
hand, the tamper-evident strip must be made relatively narrow so
that the projections protruding to the inside engage the
corresponding projections on the wall of the neck of the bottle.
For reasons of construction, this results in a relatively great
screw-on force which must be applied so that when the
tamper-evident screw closure is screwed for the first time onto a
container or bottle the tamper-evident strip can be pressed with
the protruding projections over the peripheral flange. So that the
breakaway webs do not break when the tamper-evident screw closure
is screwed on for the first time, they must be made relatively
stable. This results in turn in a comparatively large unscrewing
force which must be applied so that when the tamper-evident screw
closure is unscrewed, the tamper-evident strip is separated from
the screw cap.
[0005] It can happen that when the tamper-evident screw closure is
unscrewed the breakaway webs are only partially broken or not at
all. When the breakaway webs are only partially broken off it is
necessary to pull repeatedly at the screw cap until the
tamper-evident strip completely detaches. Then the tamper-evident
strip often runs in part above the flange which runs peripherally
on the neck of the bottle; this is an obstacle when the screw cap
is being screwed on again to close the container or bottle. If the
tamper-evident strip does not detach completely from the screw cap,
for larger dimensional tolerances of the neck it can happen that
the entire tamper-evident screw closure is unscrewed intact. In
this case the tamper-evident screw closure fails completely with
respect to its function of indicating intactness, and the
impression can be engendered in the consumer that the contents of
the container or bottle could have been tampered with. In many
known tamper-evident screw closures, after unscrewing the screw cap
and screwing it back onto the container or bottle again it is not
directly apparent that the container or bottle has already been
opened once and the tamper-evident strip has already been
separated. For the consumer this can lead to confusion which should
be avoided.
[0006] EP-A-0 916 587 discloses a tamper-evident screw closure with
a tamper-evident strip which has an internal edge bead and tabs
which project radially to the inside. The tabs are coupled to the
internal edge bead via an articulated bending region with a thinner
cross section. U.S. Pat. No. 4,748,735 discloses a similar
tamper-evident screw closure with a tamper-evident strip which has
tabs bent to the inside in the manner of fish hooks. Published U.S.
patent application No. 2001/0015341 discloses a tamper-evident
screw closure with a tamper-evident strip which is connected to the
jacket edge of the closure via webs which are provided with
scoring. Between the webs there are window-like openings in which
there are wings which are bent to the inside in the manner of a
pivot-hung window. The wings are coupled on the lower edge of the
tamper-evident strip. The tamper-evident screw closure described in
GB-A-2 269 372 has a tamper-evident strip which is connected to the
jacket of the screw closure via ribs provided with scoring. Between
the relatively stable ribs there are blocking bodies which are made
wedge-shaped projecting radially to the inside from the lower edge
of the tamper-evident ring. Material tapering which runs in the
peripheral direction forms bending joints in the manner of film
hinges for the wedge-shaped blocking bodies so that they can slide
over an annular bead which runs peripherally on the bottle when the
tamper-evident screw closure is pressed on. The closure for milk
bottles which is described in WO 97/35773 is not an actual screw
closure. Rather it is a snap closure which can be unscrewed by
turning. The snap closure has two locking systems which are matched
to a specially made bottle neck. There is also a tamper-evident
ring which is connected to the closure cap via thin joining webs
which can be broken off. From the tamper-evident ring locking clips
project radially to the inside and engage special recesses on the
periphery of the neck of the bottle when the snap closure is put
into place. Window-like recesses on the tamper-evident ring are
intended to ensure the elasticity of the locking clips.
[0007] U.S. Pat. No. 6,325,227 B1 which forms the most similar
prior art discloses a tamper-evident screw closure for bottles with
a flange which runs peripherally in a ring shape on the neck of the
bottle which has a screw cap and a tamper-evident strip which is
molded on in one piece. The screw cap has a cylindrical jacket. The
ring-shaped tamper-evident strip is provided with window-like
recesses which extend between relative solid webs. In the contact
region between the webs and the free lower edge of the jacket of
the screw cap there are breakaway webs. In the region of the
window-like recesses locking cams which are made wedge shaped
extend radially to the inside. The window-like recesses are formed
in the production of the screw closure from laterally and radially
movable slides which are delivered to the injection mold to form
the wedge-shaped locking cams.
[0008] The structure and the production of the tamper-evident screw
closures known from the prior art are relatively complex and
expensive and dictate special injection tools with laterally and
radially movable slides and the like. The more complex structure of
the molding tool results in elevated tool costs. Due to the
required mechanical movements of the additional tool parts the
cycle speeds for producing the tamper-evident rotary closures are
relatively low. Due to the larger number of moving parts the
injection tools do not have the desired long service lives either
and are more susceptible to being repaired.
[0009] The object of this invention is therefore to remedy these
disadvantages of the tamper-evident screw closures of the prior
art. A plastic tamper-evident screw closure for containers and
bottles, especially for plastic bottles, will be devised with a
tamper-evident strip which can be reliable separated from the screw
cap during unscrewing without unduly great expenditure of force.
Dimensional fluctuations of the neck of the container or bottle and
lack of roundness of the neck are to be equalized. Mounting of the
tamper-evident screw closure will be easily possible without
increased pressing or untwisting forces. The tamper-evident screw
closure is designed to enable the consumer to more easily and
reliably visually recognize intactness. It is intended to be able
to be produced in a tool which is as simple and cost-favorable as
possible in an injection molding process or in a diecasting
process. The service lives of the tools are to be higher than in
machines for producing the known tamper-evident screw closures. In
the production of the tamper-evident screw closure it is to be
possible to save material without in this way adversely affecting
functionality and reliability.
[0010] These objects are achieved in a plastic tamper-evident screw
closure for containers and bottles, especially for plastic bottles,
which has the features listed in the characterizing section of
claim 1. Developments and/or advantageous versions of the invention
are the subject matter of the dependent claims.
[0011] The invention devises a plastic tamper-evident screw closure
for containers and bottles, especially plastic bottles, consisting
of a screw cap which has a cylindrical jacket with an internal
thread, and a ring-shaped tamper-evident strip which is connected
via breakaway webs or the like to the free edge of the jacket and
is equipped with locking elements which are made for positive
engagement with an abutment which is made on the neck of the
container or bottle. The tamper-evident strip has an outside
diameter which is smaller than that of the jacket of the screw cap.
The locking elements are formed by bevelled undercut regions of the
tamper-evident strip which each run in the manner of a ring segment
between two adjacent breakaway webs and which extend from the
axially longer cylindrical inside wall to the axially shorter
outside wall of the tamper-evident strip.
[0012] The locking elements are made for positive interaction with
a peripherally running snap flange provided on the neck of the
container or bottle and extend in the axial direction perpendicular
to the unscrewing direction of the tamper-evident screw closure. To
distinguish them from blocking elements made in the manner of a
wing or tab, they extend in the peripheral direction between two
adjacent breakaway webs. When the tamper-evident screw closure is
being unscrewed, the inside wall of an undercut region which has
been beveled at an acute angle nearer the wall of the neck runs
first against the bottom of the flange. As turning continues in the
direction of opening, the pressure on the inside wall of the
undercut region increases and positive locking is increased. The
execution of the locking elements as claimed in the invention can
equalize larger fluctuations of dimensions of the neck of the
container or bottle and lack of roundness. As unscrewing continues,
the forces on the breakaway webs increase and they always break off
completely in the same quality. The forces acting on the breakaway
webs are first of all tensile forces which are superimposed to a
certain extent by shearing forces. Since there is no positive
connection of the tamper-evident strip toward the wall of the neck
and the tamper-evident strip when the tamper-evident screw closure
is unscrewed does not experience friction on the neck, the
unscrewing forces are relatively small. The screw-on forces or
press-on forces are comparatively small, since only towards the end
of the mounting process do the ring segment-like undercut regions
of the tamper-evident strip come into contact with the peripherally
running snap flange on the neck of the container or bottle. Then
the tamper-evident ring is stretched slightly in the radial
direction beyond the undercut regions and finally will slide behind
the snap flange. Due to the relatively small screw-on or press-on
forces the breakaway webs need not be especially strong. This is
expressed in turn in reduced unscrewing forces. The strength of the
breakaway webs must be so great that they are not damaged upon
removal from the mold and when the closure is applied or pressed
onto the bottle neck. By the tamper-evident strip having a smaller
outside diameter than the screw cap, in the mounted state of the
tamper-evident screw closure its undercut regions are located as
near as possible to the periphery of the neck without in doing so
rubbing against it in the unscrewing motion. Due to the lower
material use on the tamper-evident strip on the one hand there is
sufficient elasticity in mold removal and when the bottle is
closed, on the other hand, the functionality of the tamper-evident
screw closure is ensured. Moreover material can be saved by this
measure.
[0013] Due to its only relatively small undercuts, due to the
relatively elastic execution of its tamper-evident ring and due to
the execution of its locking element, the tamper-evident screw
closure made as claimed in the invention can be produced with
relatively simple tools for example in an injection molding process
or in a diecasting process. Movable slides or similar movable mold
parts can be omitted in the molding tool. In this way the tool is
mechanically less strongly loaded and it has a longer service life.
Due to the lack of additional movable mold parts, faster production
cycles can be achieved. The simpler execution of the tool directly
benefits the tool costs.
[0014] The tamper-evident strip must have a certain strength and
must still be elastic enough to be able to be radially widened when
installed on the neck of the container or bottle until the undercut
regions slide over the snap flange. For this purpose it is
advantageous for the tamper-evident strip that the wall thickness
be roughly 40 to roughly 80% of the wall thickness of the
cylindrical jacket of the screw cap in a thread-free region.
[0015] To equalize dimensional tolerances and lack of roundness of
the neck of a container or a flange, it is advantageous if the
beveled undercut region of the wall of the tamper-evident strip has
an axial length which is 1/3 to 2/3 of the axial length of the
breakaway webs.
[0016] For reasons of production engineering and in order to ensure
a buildup of pressure on the tamper-evident ring as rapidly and
greatly as possible when the tamper-evident screw closure is being
unscrewed, it is advantageous if the undercut region with the
inside wall of the tamper-evident strip forms a largely sharp-edged
transition.
[0017] The snap flange which runs peripherally on the neck of the
container or bottle is visible to the consumer when the
tamper-evident screw closure has been mounted. So that still better
visibility is ensured and in order to make it recognizable when the
screw cap has been screwed back on after opening for the first time
that the tamper-evident screw closure has already been opened once,
the breakaway webs have an axial length which is 50% to 100% of the
axial length of the outside wall of the tamper-evident strip
adjoining the undercut region. The length of the breakaway webs is
such that the annular gap interrupted by the breakaway webs between
the screw cap and the tamper-evident strip has a width from roughly
0.5 mm to roughly 5 mm. For still better detection of interrupted
connections between the tamper-evident strip and the screw cap it
has proven feasible for the separated tamper-evident strip on the
neck of the container or bottle to be able to drop a few
millimeters.
[0018] The inside diameter measured on the undercut regions of the
tamper-evident strip is feasibly larger than the inside diameter of
the screw cap on the internal thread sections. This ensures that
the tamper-evident strip can slide without obstruction over the
outside thread on the neck of the bottle when the tamper-evident
screw closure is mounted and tilting of the tamper-evident screw
closure is prevented.
[0019] In order to be able to preclude manipulation of the
tamper-evident screw closure with high reliability, the locking
elements must have a certain stiffness. This is ensured especially
also by their ring segment-shaped extension in the peripheral
direction. In this connection it is advantageous if the undercut
regions which run in the manner of a ring segment between the
breakaway webs have a peripheral extension which corresponds to 60%
to 100% of the distance measured in the peripheral direction
between two adjacent lengthwise edges of two adjacent breakaway
webs.
[0020] Containers or plastic bottles which are equipped with a
tamper-evident screw closure made as claimed in the invention are
characterized in handling of the closure by the advantages
described using the various versions of the tamper-evident screw
closure. One especially advantageous version calls for the region
of the neck of the container or bottle in which the tamper-evident
strip is located when the tamper-evident screw closure has been
screwed on to have a longer axial extension than that of the
tamper-evident strip. In this way the tamper-evident strip which
has been separated the first time the tamper-evident screw closure
is unscrewed can slide down somewhat on the neck. With the screw
cap screwed on again, it is thus immediately apparent to the
consumer that the tamper-evident screw closure has already been
opened once.
[0021] Other advantages and features will become apparent from the
following description of embodiments of the invention with
reference to the schematic drawings. The figures are not to
scale.
[0022] FIGS. 1 and 2 show a side view and a top view of a
tamper-evident screw closure of the prior art;
[0023] FIG. 3 shows a section of the tamper-evident screw closure
which has been screwed onto the neck of a container or bottle
according to cutting line D-D in FIG. 2;
[0024] FIG. 4 shows a detail of the section from FIG. 3;
[0025] FIG. 5 shows a side view of a tamper-evident screw closure
as claimed in the invention;
[0026] FIG. 6 shows a section of the tamper-evident screw closure
as shown in FIG. 5;
[0027] FIG. 7 shows a section of the tamper-evident screw closure
as shown in FIG. 5 in the screw-on position;
[0028] FIG. 8 shows a detail of the section from FIG. 7;
[0029] FIG. 9 shows a section of the tamper-evident screw closure
as shown in FIG. 5 in the screwed-on state;
[0030] FIG. 10 shows a detail of the section from FIG. 9;
[0031] FIG. 11 shows a section of the tamper-evident screw closure
as shown in FIG. 5 in the state briefly before the breakaway webs
break off; and
[0032] FIG. 12 shows a detail of the section on FIG. 11.
[0033] The tamper-evident screw closure of the prior art which is
shown in FIGS. 1-4 in different views and sections is labelled with
reference number 101 overall. The figures show the tamper-evident
screw closure 101 in the state screwed onto the neck of a container
or bottle, the container being labelled 120. The tamper-evident
screw closure 101 consists of a screw cap 102 with a jacket 103 and
a tamper-evident strip 104 which is connected via the breakaway
webs 105 to the screw cap 102. In the illustrated tamper-evident
screw closure 101 of the prior art, the tamper-evident strip 103
has the same outside diameter as the jacket 103 of the screw cap
102. Tamper-evident closures are also known in which the
tamper-evident strip has a greater outside diameter than the screw
cap. The screw cap 102 and the tamper-evident strip 104 are
produced in one piece in a plastic injection molding process or in
a plastic diecasting process. The jacket 103 of the screw cap 102
is provided on its outside with fluting or with axially running
grooves 106 or the like which facilitate gripping and holding of
the tamper-evident strip 101.
[0034] In the axially cut FIG. 3, again 101 labels the
tamper-evident screw closure with the screw cap 102 and the
tamper-evident strip 104. The jacket of the screw cap 102 is
labelled with reference number 103. On the edge of the jacket 103
which runs annularly the breakaway web is labelled with reference
number 105. The container or the bottle 120 has a neck which is
provided with reference number 121. External thread sections 122 on
the neck 121 of the container or bottle engage the internal thread
sections 107 of the jacket 103 of the screw cap 102. The neck 121
of the container or bottle is provided with projections 123 which
interact with the corresponding profiling 108 which is made on the
inside wall 109 of the tamper-evident strip 104 (FIG. 4).
[0035] FIG. 4 shows the section surrounded by the broken line in
FIG. 3 on a larger scale. It shows that the profiling 108 of the
inside wall 109 of the jacket 103 is made for example as lengthwise
grooves or axial strips which are engaged by the projections 123
which are located in a ring shape on the neck 121 of the container
or bottle. The projections 123 and profiling 108 form a rotary lock
which becomes active when the tamper-evident screw closure 101 is
unscrewed from the neck 121 of the container or bottle. The lock
prevents the tamper-evident strip 104 from turning concomitantly
with the screw cap 102 and the breakaway webs 105 are finally
sheared off upon further unscrewing. On the inside wall 109 of the
tamper-evident strip 104 there is a peripheral annular bead 110
which prevents the separated tamper-evident strip 104 from dropping
off the neck 121 of the container and bottle. The annular bead 110
extends behind the projections 123 on the neck 121 of the container
or bottle 121 and when the tamper-evident screw closure 101 is
unscrewed supports the breaking of the breakaway webs 105 by its
preventing the tamper-evident strip 104 from following the axial
lifting motion of the screw cap 102.
[0036] The tamper-evident screw closure as claimed in the invention
which is shown in FIGS. 5 and 6 is labelled overall with reference
number 1. It comprises a screw cap 2 with a cylindrical jacket 3
and a tamper-evident strip 4 which is connected via breakaway webs
2 to the free edge of the jacket 3 of the screw cap 2. The outside
surface of the jacket 3 is provided with fluting or with lengthwise
ribs 6 or the like in order to facilitate gripping and holding of
the tamper-evident screw closure when screwing onto or off of the
neck of a container or bottle. The tamper-evident strip 4 has an
outside diameter which is smaller than the outside diameter of the
jacket 3 of the screw cap 2. As is apparent from FIGS. 5 and 6, on
the tamper-evident strip 4 locking elements are formed which have
the shape of bevelled undercut regions 8. The undercut regions 8
have an axial length t which is roughly 1/3 to 2/3 of the axial
length s of the breakaway webs 5. They each extend between two
adjacent breakaway webs 5. The length of the breakaway webs 5 is
especially such that an annular gap 9 between the screw cap 2 and
the tamper-evident strip 4 which is interrupted in the peripheral
direction by the breakaway webs 5 has a width which is roughly 0.5
to roughly 5 nm. The width of the ring segment-like undercut
regions 8 measured in the peripheral direction is roughly 60% to
roughly 100% of the distance measured in the peripheral direction
between two adjacent lengthwise edges of two adjacent breakaway
webs.
[0037] FIGS. 7 and 8 and FIGS. 9 and 10 and FIGS. 11 and 12 show
the tamper-evident screw closure in three different stages of
screwing on and off with the pertinent detail of the area
surrounded by the broken line. The container or bottle is indicated
by reference number 20. The neck of the bottle or container is
labelled with reference number 21.
[0038] FIGS. 7 and 8 show the tamper-evident screw closure 1 which
is mounted for the first time on the neck 21 of the bottle. In
particular the state is shown in which the tamper-evident strip 4
which has a smaller outside diameter than the jacket 3 of the screw
cap 2 is pressed over a snap flange 23 which is used as the
abutment for the ring segment-like undercut regions 8. Here the
tamper-evident strip 4 is elastically widened. Elasticity is
ensured by the material, the smaller outside diameter of the
tamper-evident strip 4, and by the wall thickness of the
tamper-evident strip 4 which is less compared to the relatively
rigid screw cap 2. In this connection the tamper-evident strip 4
has a wall thickness b which is roughly 40% to 80% of the wall
thickness a of the screw cap 2 in the region of its jacket (FIG.
10). When mounted for the first time, the tamper-evident screw
closure 1 is pressed on or screwed on. The neck 21 of the container
or bottle is provided with sections 22 of the external thread which
engage the sections 7 of the internal thread on the screw cap
2.
[0039] In FIGS. 9 and 10 the tamper-evident screw closure 1 is
mounted entirely on the neck 21 of the container or bottle. The
tamper-evident strip 4 and the breakaway webs 5 are intact and run
in the immediate vicinity to the neck 21 of the container or
bottle. FIG. 9 clearly shows that the tamper-evident strip 4 has a
smaller outside diameter than the jacket 3 of the screw cover 2.
The ring segment-like undercut regions 8 of the tamper-evident
strip 4 extend behind the snap bead 23 which runs peripherally on
the neck 21 of the container or bottle. The detailed representation
in FIG. 9 shows that the ring segment-like undercut regions 8
extend from an axially longer inside wall 42 to an axially shorter
outside wall 41 of the tamper-evident strip 4. The breakaway webs 5
have an axial length which is 50% to 100% of the axial length of
the outside wall 41 of the tamper-evident strip 4 which adjoins the
undercut region 8. It is likewise apparent that the region of the
neck 21 of the container or bottle in the immediate vicinity of the
tamper-evident strip 4 has a greater axial extension than the
tamper-evident strip. In this way the tamper-evident strip 4 which
has been separated from the screw cap 2 when unscrewed can slide
down a few millimeters on the neck 21 of the container or
bottle.
[0040] FIG. 11 and the detail in FIG. 12 finally show the
tamper-evident screw closure 1 when unscrewed from the neck 21 of
the container or bottle. The undercut regions 8 which form a
largely sharp-edged transition with the inside wall 42 of the
tamper-evident strip 4 positively adjoin the bottom of the snap
bead 23. The tamper-evident strip 4 is slightly widened by the
tensile forces and by the bevel of the undercut regions 8 and is
tilted to the outside. As the tamper-evident screw closure 1
continues to be unscrewed, the tensile forces acting on the
tamper-evident strip 4 and the breakaway webs 5 increase. This is
indicated in FIG. 12 by the necking of the illustrated breakaway
web 5. The tamper-evident strip 4 is tilted still further to the
outside and the positive locking of the undercut regions 8 with the
snap bead 23 is increased. A further increase of the tensile forces
finally leads to breaking of the connection of the breakaway webs 5
to the jacket 3 of the screw cap 2. In this way the tamper-evident
strip 4 is separated from the screw cap 2 and it can slide down on
the neck 21 of the container or bottle. The snap bead 23 prevents
the tamper-evident strip 4 from being lost. If the screw cap 2 is
again screwed onto the neck 21 of the container or bottle, it is
immediately apparent that the tamper-evident screw closure 1 has
already been opened.
[0041] The tamper-evident screw closure as claimed in the invention
consists of plastic and can be produced for example in an injection
molding process or in a diecasting process. Due to the simplicity
of its construction it can be produced with relatively simple tools
which have a smaller number of movable components. This results in
longer service lives and faster cycle times. The construction of
the tamper-evident screw closure allows the consumer to ascertain
directly and unmistakably whether the tamper-evident screw closure
has already been opened once. The tamper-evident screw closure has
been explained on the example of a screw cap and a tamper-evident
strip with a circular cross section. It goes without saying that
the cross section of the screw cap can also be made polygonal or
elliptical or egg-shaped or the like. The applies analogously to
the outside contour of the tamper-evident strip as well. The screw
cap can also have a double jacket. In this connection the execution
as claimed in the invention is referenced to the inside jacket.
* * * * *