U.S. patent application number 12/093835 was filed with the patent office on 2009-09-10 for jaw seals for container closure assemblies.
This patent application is currently assigned to BEESON AND SONS LIMITED. Invention is credited to Roger Milner King.
Application Number | 20090223922 12/093835 |
Document ID | / |
Family ID | 39591869 |
Filed Date | 2009-09-10 |
United States Patent
Application |
20090223922 |
Kind Code |
A1 |
King; Roger Milner |
September 10, 2009 |
JAW SEALS FOR CONTAINER CLOSURE ASSEMBLIES
Abstract
A container closure assembly comprising a threaded closure with
a sealing plug (24) and a sealing skirt (20) pinching a container
lip (5). The skirt and the plug comprise sealing ribs (21, 22, 26,
27) that engage the lip of the container The ribs are located at
substantially equal longitudinal distances from the base (3) of the
closure.
Inventors: |
King; Roger Milner;
(Buckinghamshire, GB) |
Correspondence
Address: |
Stephen B. Salai, Esq.;Harter Secrest & Emery LLP
1600 Bausch & Lomb Place
Rochester
NY
14604-2711
US
|
Assignee: |
BEESON AND SONS LIMITED
Stoke Poges
GB
|
Family ID: |
39591869 |
Appl. No.: |
12/093835 |
Filed: |
November 21, 2006 |
PCT Filed: |
November 21, 2006 |
PCT NO: |
PCT/GB06/04345 |
371 Date: |
October 2, 2008 |
Current U.S.
Class: |
215/330 ;
215/329; 215/344; 215/346 |
Current CPC
Class: |
B65D 41/0471 20130101;
B65D 41/0421 20130101; B65D 41/325 20130101 |
Class at
Publication: |
215/330 ;
215/344; 215/329; 215/346 |
International
Class: |
B65D 41/04 20060101
B65D041/04; B65D 53/00 20060101 B65D053/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 21, 2005 |
US |
11283983 |
Mar 14, 2006 |
GB |
0605122.1 |
Claims
1. A container closure assembly comprising: a container neck having
side walls defining an opening at one end thereof and a lip
extending around the opening; a closure for said neck, the closure
having a base portion and a threaded skirt portion; a first screw
thread on the neck; a second screw thread on an inner surface of
the threaded skirt of the closure; said first and second screw
threads being configured to enable a user to secure, remove and
resecure the closure into a sealing position on the neck by
rotation of the cap on the neck; a sealing plug extending from said
base portion of the closure inside and substantially concentric
with said threaded skirt portion of the closure, wherein the
sealing plug comprises two or more longitudinally spaced
circumferential sealing ribs on an outer surface of said sealing
plug for engagement with an inner surface of the container neck
proximate to said lip when the closure is secured on the container
neck; and a sealing skirt extending from said base portion of the
closure intermediate said sealing plug and said threaded skirt
portion of the closure and substantially concentric with said
sealing plug and said threaded skirt portion of the closure,
wherein the sealing skirt comprises two or more longitudinally
spaced circumferential sealing ribs on an inner surface of said
sealing skirt for engagement with an outer surface of the container
neck proximate to said lip when the closure is secured on the
container neck; wherein in use two of said sealing ribs on the
sealing plug are located at substantially the same longitudinal
distances from the base portion of the closure as two of the
circumferential sealing ribs on the sealing skirt, whereby the lip
of the container neck is pinched between the sealing ribs on the
closure plug and the sealing skirt at two or more longitudinally
spaced locations when the closure is in the secured position on the
container neck.
2. A container closure assembly according to claim 1, wherein at
least one of the sealing ribs has a substantially triangular
cross-section.
3. A container closure assembly according to claim 1, wherein at
least one of the sealing ribs has a height in the range of 10 to
250 micrometers.
4. A container closure assembly according to claim 1, wherein the
container lip is rounded in longitudinal cross-section.
5. A container closure assembly according to claim 4, wherein at
least one of the circumferential sealing ribs on the sealing plug
and the sealing skirt forms a pinch across the said rounded
container lip.
6. A container closure assembly according to claim 1, wherein the
sealing plug and the sealing skirt extend substantially equal
heights above the base of the closure.
7. A container closure assembly according to claim 6, wherein the
sealing plug and the sealing skirt are profiled so as to define a
symmetrical jaw for gripping the container neck.
8. A container closure assembly according to claim 1, wherein
respective lower ends of the sealing skirt and the sealing plug
distal from the base of the closure are profiled to provide further
circumferential sealing ribs on each of the sealing skirt and the
sealing plug for gripping the neck of the closure.
9. A container closure assembly according to claim 1, wherein the
closure can be secured and resecured on the container neck by a
single smooth rotation through 360.degree. or less, preferably
through 180.degree. or less, and more preferably through about
90.degree..
10. A container closure assembly according to claim 1, wherein the
first and second threads are multiple start threads.
11. A container closure assembly according to claim 1, wherein the
first and second threads are substantially continuous helical
threads.
12. A container closure assembly according to claim 1, wherein the
container and closure further comprise complementary locking
elements on the container neck and the closure that block or resist
unscrewing of the closure from the fully secured position on the
container neck until a predetermined minimum opening torque is
applied.
13. A container closure assembly according to claim 12, wherein
said complementary locking elements comprise first and second
locking projections on the container neck and the threaded closure
skirt, and either said first locking projection is located
longitudinally overlapping with and radially spaced from an upper
end of a first thread segment, or said second locking projection is
located longitudinally overlapping with and radially spaced from a
lower end of a second thread segment, whereby the said first or
second locking projection defines an extension of the thread path
defined by the thread segments on the neck or the closure.
14. A container closure assembly according to claim 1, further
comprising a projecting stop surface on one of the container neck
and the closure skirt for abutment against a second stop or a
thread on the other of the container neck or the closure to block
over-tightening of the closure beyond a predetermined angular
sealing position of the closure on the container neck.
15. A container closure assembly according to claim 1, wherein the
torque required to secure the closure in a sealing position on the
container neck is from about 0.7 Nm to about 0.9 Nm.
16. A container closure assembly according to claim 1, wherein the
assembly achieves a sealing pressure around at least one
circumferential surface between the container neck and the closure
at the fully closed position of at least about 7 MPa (1000
psi).
17. A beverage container comprising a container closure assembly
according to claim 1.
18. A beverage container according to claim 17 which is a
carbonated beverage container.
Description
[0001] The present invention relates to improved seals for
container closure assemblies. The invention is especially
applicable to the sealing of containers in substantially gas-tight
and liquid-tight fashion, such as the sealing of carbonated and
non-carbonated beverage containers.
[0002] It is well known to provide beverage containers of glass,
paper, card, metal or plastic having a screw top that can be
resecured on the bottle neck. It is desirable to provide such
containers with a screw top closure assembly that provides an
airtight and liquid-tight seal to retain the a quality of the
beverage both during initial transport and storage, and after
partial consumption of the contents when the closure has been
resecured onto the container neck.
[0003] Certain existing container and closure assemblies make use
of an elastomeric liner in the base of the closure cap. This liner
is pressed against the lip of the bottle neck when the cap is
screwed firmly onto the bottle neck, and the compression between
the soft, deformable liner and the lip of the container provides a
tight seal. Unfortunately, the manufacture and insertion of the
liner into the closure cap are relatively costly additional process
steps. Furthermore, care must be taken not to over-tighten such
closures onto the container neck, since the liner can become
brittle or damaged if excessive, pressure is applied thereto.
[0004] It is also known to provide a cylindrical plug seal
projecting downwardly from the base of the closure cap, such that
the plug forms an interference fit with an inner surface of the
bottle neck close to the lip of the bottle. Effective sealing by
such plug seals requires the cap to be screwed down very tightly on
the container neck in order to deform the base of the cap and
thereby force the plug radially outwardly into a tight sealing
engagement with the container neck. It is very often the case that
such caps are under-tightened, especially by children and elderly
users. Furthermore, a sufficient sealing force can only be achieved
by the use of threads on the cap and the neck having a low pitch,
such that the closure torque applied to the cap is leveraged into a
very strong downward sealing force between the lip of the container
and the closure base.
[0005] WO02/42171 describes a container closure assembly
comprising: a container neck having side walls defining an opening
at one end thereof and a lip extending around the opening, wherein
an inner surface of the side walls proximate to the lip is inwardly
tapered; a closure for the neck, the closure having a base portion
and a skirt portion; a first screw thread on the neck; a second
screw thread on an inner surface of the skirt of the closure; the
first and second screw threads being configured to enable a user to
secure, remove and resecure the closure into a sealing-position on
the neck by rotation of the cap on the neck; a sealing plug
extending from the base portion of the closure inside and
substantially concentric with the skirt portion of the closure,
wherein the sealing plug comprises a plurality of circumferential
sealing ribs on an outer surface of the sealing plug for engagement
with the inner surface of the container neck when the closure is
secured on the container neck; at least one flexible sealing fin
between the sealing plug and the closure skirt for engagement with
the lip of the container when the closure is secured on the
container neck; and at least one circumferential sealing rib on an
inner surface of the closure skirt for engagement with an outer
surface of the container neck proximate to the lip when the closure
is secured on the container neck.
[0006] FR-A-2327930 describes container closure assemblies
comprising: a container neck; a closure for the neck; mutually
engageable screw threads on the closure and the neck; and a sealing
plug extending from the base of the closure for insertion into the
container neck. The sealing plug is provided with two
circumferential sealing ribs on an outer surface thereof for
engagement with the inner-surface of the container neck when the
closure is secured on the container neck. The assembly further
includes a flexible sealing fin projecting from the base of the
closure between the sealing plug and the closure skirt for
engagement with the lip of the container when the closure is
secured on the container neck.
[0007] Further container and closure assemblies incorporating a
ribbed sealing plug on the closure cap are described in
DE-A-4207997, WO99/44896, U.S. Pat. No. 3,944,104, FR-A-2340865,
WO2005/058720 and GB-A-2022063.
[0008] A need remains for a screw-top container and closure
arrangement that can provide an effective seal without the need
four a liner, and also without the need for a strong axial sealing
force between the container neck and the closure.
[0009] The present invention provides a container closure assembly
comprising: a container neck having side walls defining an opening
at one end thereof and a lip extending around the opening; a
closure for the neck, the closure having a base portion and a
threaded skirt portion; a first screw thread on the neck; a Second
screw thread on an inner surface of the threaded skirt of the
closure; the first and second screw threads being configured to
enable a user to secure, remove and resecure the closure into a
sealing position on the neck by rotation of the cap on the neck; a
sealing plug extending from the base portion of the closure inside
and substantially concentric with the threaded skirt portion of the
closure, wherein the sealing plug comprises two or more
longitudinally spaced circumferential sealing ribs on an outer
surface of the sealing plug for engagement with an inner surface of
the container neck proximate to the lip when the closure is
secured, on the container neck. The closure further comprises a
sealing skirt extending from the base portion of the closure
intermediate the sealing plug and the threaded skirt portion of the
closure and substantially concentric with the sealing plug and the
threaded skirt portion of the closure, wherein the sealing skirt
comprises two or more longitudinally spaced circumferential sealing
ribs on an inner surface of the sealing skirt for engagement with
an outer surface of the container neck proximate to the lip when
the closure is secured on the container neck; wherein in use two of
the sealing ribs on the sealing plug are located at substantially
the same longitudinal distances from the base portion of the
closure as two of the circumferential sealing ribs on the sealing
skirt, whereby the lip of the container neck is pinched between the
sealing ribs on the closure plug and the sealing skirt at two or
more longitudinally spaced locations when the closure is in the
secured position on the container neck.
[0010] The inventive arrangement of sealing plug, sealing skirt and
sealing ribs is new, and provides surprisingly improved sealing at
low sealing forces.
[0011] Suitably, the closure assembly according to the present
invention is applied to a carbonated beverage container, such as a
molded plastic or glass carbonated beverage bottle.
[0012] Suitably, the container lip is rounded to provide for easy
and comfortable drinking directly from the container neck, and more
suitably it is fully radiused (i.e. semi-circular) in
cross-section. It is a further advantage of the present invention
that the sealing arrangement is so effective that it can provide a
pressure-tight seal on a fully radiused container lip. Suitably, at
least one of the circumferential sealing pinches provided by the
circumferential sealing ribs is applied across the rounded portion
of the container lip. That is to say, respective sealing ribs on
the sealing plug and the sealing skirt engage the rounded surface
of the lip near the top of the neck.
[0013] It is an advantage of the present invention that it can
provide an effective pressure-tight seal on a conventional
container neck having internal walls substantially parallel to the
longitudinal axis of the neck. However, in some embodiments the
inner sealing surface of the container neck optionally be inwardly
tapered. That is to say, the internal diameter of the neck may
decrease with increasing distance from the lip. Suitably, in these
embodiments the interior of the neck presents a substantially
inverted, truncated conical surface. Suitably, the taper of the
inner sealing surface of the container neck is from about 1.degree.
to about 10.degree. from the longitudinal axis of the neck, more
suitably from about 2.degree. to about 6.degree.. The taper can
assist effective sealing of the plug against the inner wall of the
neck.
[0014] The sealing plug is suitably in the form of a tube,
preferably a cylinder, typically projecting perpendicularly
downwardly from the base of the closure and preferably
substantially concentric with the threaded skirt and coaxial with
the longitudinal axis of the closure. The height of the sealing
plug is suitably from about 1 mm to about 5 mm, for example about
1.5 mm to about 2.5 mm. The sealing plug is normally molded
integrally with the base of the closure cap. The mean thickness of
the tubular wall of the sealing plug is suitably from about 0.5 mm
to about 2 mm, for example about 0.7 mm to about 1.2 mm. This gives
the sealing plug the right degree of resilience and strength for
the desired sealing function.
[0015] Suitably, the outer surface of the sealing plug may be
tapered inwardly from the base of the closure, for example it may
taper in a manner substantially complementary to the optional
inward taper of the interior of the container neck. The mean angle
of taper is suitably from 1.degree. to 10.degree. from the
longitudinal axis of the neck, more suitably from 2.degree. to
6.degree..
[0016] The container closure in the assembly according to the
present invention further comprises a circumferential sealing
skirt. The sealing skirt is separate and radially spaced from the
threaded closure skirt that engages the thread on the outside of
the container neck. Suitably, the sealing skirt is substantially
tubular, preferably cylindrical, and projects downwardly from the
base of the closure intermediate the closure skirt and the sealing
plug. The sealing skirt is preferably substantially concentric with
the threaded skirt and the sealing plug, and coaxial with the
longitudinal axis of the closure. The height of the sealing plug is
suitably from about 1 mm to about 5 mm, for example about 1.5 mm to
about 2.5 mm. The height of the sealing plug in certain embodiments
is substantially equal to the height of the sealing plug. The
sealing skirt is normally molded integrally with the base of, the
closure cap. The mean thickness of the tubular wall of the sealing
skirt is suitably from about 0.5 mm to about 2 mm, for example
about 0.7 mm to about 1.2 mm. This gives the sealing skirt the
right degree of resilience and strength for the desired sealing
function.
[0017] The assembly according to the present invention further
comprises two or more circumferential sealing ribs on an outer
surface of the closure plug for engagement with an inner surface of
the container neck, and two or more circumferential sealing ribs on
an inner surface of the closure skirt for engagement with an outer
surface of the container neck. Two or more of the further
circumferential sealing ribs on the sealing skirt are located at
substantially the same heights above the base of the closure,
respectively, as two or more of the circumferential sealing ribs on
the sealing plug, whereby they cooperate to apply a symmetrical
sealing pinch at two or more vertically spaced locations on the
container neck when the closure is in the sealing position on the
neck. That is to say, the ribs apply a symmetrical sealing pinch at
two or more vertical heights below the top of the container
lip.
[0018] Suitably, there are two of the sealing ribs on the sealing
plug and/or on the sealing skirt, but in some embodiments there are
suitably from 3 to 10 of the ribs, and for example 4 to 6 ribs.
[0019] Suitably, at least one of the sealing ribs has a
substantially triangular cross-section when the closure cap is
viewed in longitudinal cross-section, for example substantially
equilateral triangular. This enables the sealing force to be
concentrated in the tip of the sealing rib to maximise sealing
effectiveness. Suitably, at least one of the sealing ribs has a
height in the range of 10 to 500 micrometers, more suitably 50 to
250 micrometers. The height is defined as the maximum distance that
the sealing rib projects above the adjacent surface of the sealing
plug or sealing skirt, when the cap is viewed in longitudinal
cross-section. Such micro sealing ribs are especially effective to
concentrate the sealing force and achieve an effective seal with a
substantially smooth sealing surface on the container neck.
Furthermore, such micro ribs are especially easy to mold in
high-speed cap molding equipment, and to bump off the mold mandrel
of the equipment after molding.
[0020] A further advantage of using multiple sealing ribs on the
sealing plug and the sealing skirt is that the plurality of sealing
ribs may have more than one dimension in order to optimise sealing.
For example, the size of the sealing rib closest to the base of the
closure may be greater than the size of the sealing rib remote from
the base of the closure. This allows the sealing rib closest to the
base of the closure (i.e. closest to the lip of the container) to
deform more that the sealing rib furthest from the base of the
closure.
[0021] Suitably, the sealing plug and the sealing skirt are
profiled so as to define a symmetrical jaw for gripping the
container neck. The circumferential sealing ribs appear as "teeth"
of the jaw in longitudinal cross-section. Suitably, respective
lower ends of the sealing skirt and the sealing plug distal from
the base of the closure are profiled to provide further
circumferential sealing ribs on each of the sealing skirt and the
sealing plug for gripping the neck of the closure.
[0022] The use of multiple symmetrically disposed circumferential
sealing ribs on a sealing plug and a sealing skirt, each of which
has a degree of radial flexibility, allows a pressure-tight seal to
be formed between the container neck and the closure without
application of excessive force to the closure, and without any need
for a sealing liner in the base of the closure.
[0023] The container closure assembly according to the present
invention is especially suitable for use in conjunction with thread
arrangements that are quick and easy to secure and resecure,
wherein the closure can be secured and resecured on the container
neck by a single, smooth rotation through 360.degree. or less, more
suitably 180.degree. or less, and most suitably about
90.degree..
[0024] Suitably, the first and second threads are multiple start
threads such as two-start threads or three-start threads, and more
suitably they are four-start threads. This further assists securing
of the closure on the neck, since the user needs to rotate the cap
less in order to find a thread start. Suitably, the threads are
substantially free-running or parallel threads. That is to say, the
threads on the closure and cap slide past each other freely without
forming an interference fit between the thread segments on the
closure and cap.
[0025] Suitably, the first and second threads are continuous
helical threads. That is to say, they are not bayonet-type threads
that require a stepped motion of the closure to secure the closure
on the neck, but rather they define a substantially continuous
helical thread path having a thread gradient less than 90 degrees
substantially throughout. Suitably the threads have a mean thread
pitch of from 5.degree. to 25.degree., more suitably from
10.degree. to 20.degree.. Typically, the minimum vertical
displacement of the cap between the fully secured position on the
container neck and a fully disengaged position of the cap on the
neck of from about 2 mm to about 10 mm, for example from about 4 mm
to about 8 mm.
[0026] Steeply pitched threads provide advantages in terms of ease
of use and more reliable separation of tamper-evident rings from
the closure skirt. However, it will be appreciated that such
steeply pitched threads result in a relatively small leverage of
rotational force applied to the closure into downward force on the
closure, and it is a feature of the sealing arrangement according
to the invention that it can provide a reliable pressure-tight seal
without strong downward force being applied to the closure as in
previous sealing arrangements.
[0027] It is an advantage of the assemblies according to the
present invention that they can provide a pressure tight seal
without the need for additional circumferential flexible sealing
fins between the sealing plug and the sealing skirt of the kind
described in WO02/42171. Nevertheless, in certain embodiments, the
closure in the assemblies according to the present invention may
further comprise one or more circumferential flexible sealing fins
between the sealing plug and the sealing skirt for engagement with
the lip of the container when the closure is secured on the
container neck. The sealing fins may have their base in the base of
the closure between the sealing skirt and the sealing plug, or they
may extend inwardly or outwardly and downwardly from the base of
the sealing skirt or the sealing plug.
[0028] Suitably, the closure comprises two sealing fins extending
around the closure in concentric fashion. Suitably, two sealing
fins are disposed substantially symmetrically on either side of the
container lip to provide a balanced sealing pinch on the lip. In
these embodiments, the container closure assembly comprises a
second sealing fin extending downwardly and inwardly from the base
of the closure between the sealing plug and the sealing skirt. The
first and second sealing fins then seal against opposite sides of
the container lip, suitably in substantially symmetrical and
balanced fashion. The first and second sealing fins flex in
opposite directions as the closure is secured onto the container
neck. This dual action ensures that at least one, and usually both,
of the sealing fins makes a pressure-tight seal against the
lip.
[0029] Suitably, the height of the sealing fins is greater than
their width at their base. Suitably, the cross-section of the
sealing fins is substantially in the shape of an isosceles
triangle. Suitably, at least one sealing fin has a height of from 1
to 4 mm.
[0030] Suitably, at least one sealing fin abuts against a stop
surface when the closure is secured on the container neck.
Suitably, two flexible fins are provided for sealing on either side
of the container lip, as described above, and the two stop surfaces
are provided by the bases of the sealing plug and the sealing skirt
for abutment against each of the sealing fins at the fully secured
and pressure-tight position.
[0031] Suitably, the container and closure further comprise
complementary locking elements on the container neck and the
closure that block or resist unscrewing of the closure from the
fully secured position on the container neck until a predetermined
minimum opening torque is applied. For example, the locking
elements may comprise a longitudinal locking rib on one of the
container neck or the skirt portion of the closure, and a
complementary locking ramp on the other of the container neck and
the skirt portion of the closure, the locking rib abutting against
the retaining edge of the locking ramp when the closure is fully
secured on the container neck.
[0032] In certain embodiments, the first and second locking
projections (side catches) longitudinally overlap the first and/or
the second thread segments when the closure is in said fully
engaged position on the container neck. In other words, the first
and second locking projections are not located entirely above or
below the threads (the terms above and below refer to relative
positions along the longitudinal axis of the assembly), but are
located, at least in part, radially in-between the threads. The
side catches are preferably located adjacent to an end of the
threads. This enables the entire thread assembly to be made more
compact in the longitudinal (vertical) direction, thereby reducing
the total amount of moulding material needed to make the assembly,
and the space taken up by the assembly. In certain embodiments, it
also enables the neck thread to be made more suitable for
consumption directly from the neck.
[0033] Typically, the first and second locking elements are
situated near the lower end of the threads when the closure is
fully secured on the container. Preferably, the first and/or second
locking projections do not extend below the lower edge of the first
or second thread segments when the closure is in said fully engaged
position on the container neck. The term "lower" refers to the part
of the neck thread furthest from the opening of the container neck.
In such assemblies, the locking projections are preferably located
substantially completely radially between the threads and not above
or below the threads. Preferably, the locking projections on the
neck are not joined at the lower edge to a circumferential flange
or shoulder (e.g. the shoulder used to retain a tamper-evident
band), thereby enhancing the flexibility of the locking projections
and enhancing the "click-to-close" noise.
[0034] Further to the aforesaid, at least one, and preferably both
of the complementary locking projections on the neck and/or the
closure is substantially separate from the thread segments and can
flex substantially independently of the thread segments in order to
provide the snap-fitting and clearly audible click as the fully
secured position of the closure on the neck is reached. In general,
a radially innermost vertex of the second locking element on the
closure skirt rides over a radially outermost vertex of the first
locking element on the container neck as the fully secured position
is approached. The second locking element then rides back over the
outermost vertex of the first locking element when the closure is
removed from the secured position, for example when opening the
assembly.
[0035] At least one, and preferably both of the complementary
locking projections on the neck and/or the closure has a length in
the longitudinal direction (i.e. along the rotational axis of the
closure assembly) of from about 1 mm to about 6 mm, for example
from about 2 mm to about 4 mm. At least one, and preferably both of
the complementary locking projections on the neck and/or the
closure has a height of from about 0.25 mm to about 2 mm, for
example from about 0.5 mm to about 1.5 mm. In any case the height
of the locking projections is normally less than the average height
of the respective thread segments. At least one, and preferably
both of the complementary locking projections on the neck and/or
the closure has a maximum width (i.e. around the circumference of
the neck or closure skirt) of from about 0.5 mm to about 3 mm, for
example from about 1 mm to about 2 mm. At least one, and preferably
both of the complementary locking projections on the neck and/or
the closure has a ratio of the maximum height to the maximum width
of at least about 0.5, more preferably at least 1, for example from
about 1 to about 5.
[0036] In suitable embodiments, the first locking projection is
located longitudinally overlapping with and radially spaced from an
upper end of a first thread segment. In other embodiments, the
second locking projection is located longitudinally overlapping
with and radially spaced from a lower end of a second thread
segment. These latter embodiments are preferred, since the first
locking projections are then located further from the opening of
the container neck. The circumferential spacing between the
projections and the respective thread segments in these embodiments
is typically from about 1 mm to about 10 mm, for example from about
1 mm to about 4 mm. In these embodiments, the radially spaced
locking projections may abut against the thread segments of the
other assembly component as the assembly is screwed together. That
is to say, the radially spaced projections may define a part of the
thread path on the enclosure or neck. For example, in the case
where there are relatively long thread segments on the closure
skirt defining a thread path for relatively short thread segments
on the container neck, the locking projections on the closure skirt
may be radially spaced from the lower end of the relatively long
thread segments on the closure skirt and may thereby define an
extension at the start of the thread path followed by the thread
segments on the neck when the closure is applied to the neck. This
method of using the locking projections to form an extension of the
thread path on one of the neck or the closure solves the problem of
providing larger locking projections that overlap with the threads,
but do not interfere with the running of the threads. The locking
projections are generally in the line of and, as it were, are
extensions of the thread path on one of the neck or the
closure.
[0037] The assemblies according to the present invention may
comprise more than one pair of complementary locking projections on
the container neck and the closure. Preferably there are at least
two such complementary pairs radially spaced around the neck and
closure skirt. There will normally be at least one pair for each
thread start, for example there may be four pairs radially spaced
around the neck and closure skirt.
[0038] Preferably, the locking projections on the neck and the
closure, skirt are radially positioned such that they are in
abutment when the closure is at the fully closed and sealing
position on the container neck. That is to say, the projection on
the closure has ridden over one side of, and is resting in abutment
with the opposite side of, the corresponding projection on the
container neck at said fully closed and sealing position. This
ensures that there is no play in the cap at said closed and sealing
position that could allow leakage from the seal. Preferably, when
the projections are in abutment at the closed and sealing position,
the closure skirt and/or the projections are still slightly
distorted such that a resilient force is exerted between the
projections in abutment. This resilient force is leveraged by the
abutment into a closing torque between the closure and the neck
that urges the closure into the fully closed and sealing position.
This can ensure that the respective sealing surfaces of the
container neck and the closure are automatically seated against
each other, even though the closure may not be screwed down
especially tightly. Furthermore, the locking projections allow for
considerably lower manufacturing tolerances in the moulding of the
assembly, since effective sealing is achieved over a broader range
of radial sealing positions due to the interaction between the
locking projections and the radial deformation of the closure
skirt.
[0039] The advantages of locking projections that urge the closure
into the sealing position are discussed in detail in WO93/01098,
the entire content of which is incorporated herein by
reference.
[0040] The complementary locking elements according to the present
invention provide a number of other important advantages, besides
urging the closure into the fully secured and sealing position as
described above. Firstly, they prevent accidental backing off of
the closure from the fully engaged and sealing position on the
container neck due to pressure from inside the container. These
elements enable more steeply pitched threads and free running
(parallel) threads to be used without risk of the closure
unscrewing spontaneously. The use of more steeply pitched threads
in turn makes it easier to remove and resecure the closure.
[0041] In some embodiments, the locking elements according to the
present invention may also provide a positive "click" when the
fully engaged and sealing position of the closure on the container
neck is reached, thereby giving the user a positive indication that
the closure is in the closed (sealed) position. This system also
ensures that exactly the right degree of compression is applied
between the container and closure to achieve an effective airtight
seal.
[0042] Suitably, the container closure assembly according to the
present invention further comprises a projecting stop surface on
one of the container neck and the closure skirt for abutment
against a second stop or a thread on the other of the container
neck or the closure to block over-tightening of the closure beyond
a predetermined angular sealing position of the closure on the
container neck. The stop elements act in conjunction with the
locking arrangement to ensure that exactly the right degree of
screwing of the closure is achieved in order to provide a
pressure-tight seal with the sealing arrangement of the present
invention.
[0043] Suitable locking and stop arrangements are described in
detail in WO 91/18799, WO 95/05322 and WO2005/058720, the entire
contents of which are expressly incorporated herein by
reference.
[0044] The container closure assembly also suitably comprises a
tamper-evident safety feature. The safety feature preferably
includes a tamper-evident ring that is initially formed integrally
with the skirt of the container closure and joined to the lower
edge thereof by one or more frangible bridges. The tamper-evident
ring is retained on the container neck when the closure is removed
from the neck for the first time, suitably by abutment with the
underside of a circumferential retaining lip provided on the
container neck below the threads.
[0045] In certain embodiments, the tamper-evident ring comprises a
plurality of integrally formed, flexible, radially inwardly
pointing retaining tabs to retain the ring under the retaining lip.
In these embodiments, ratchet projections may also be provided on
the container neck below the circumferential retaining lip and
radially spaced around the container neck to block rotation of the
tamper-evident ring on the container neck in an unscrewing
direction and thereby assist separation of the tamper-evident ring
from the neck. The structure and operation of the tamper-evident
ring feature according to these embodiments may be as described and
claimed in our International Patent Publication WO94/11267, the
entire contents of which are expressly incorporated herein by
reference.
[0046] Suitably, the torque required to secure the closure in a
sealing position on the container neck is less than 1.2 Nm, more
suitably less than 1 Nm and most suitably from about 0.7 to about
0.9 Nm. This is the torque required to engage the complementary
locking arrangement (where present) at the sealing position, and/or
otherwise the force required to substantially eliminate gas leakage
at normal carbonated beverage pressure differentials.
[0047] Suitably, the assembly achieves a sealing pressure around at
least one circumferential surface between the container neck and
the closure at the fully closed position of at least about 7 MPa
(1000 psi), suitably at least about 10.5 Mpa (1500 psi), suitably
over a temperature range of from about 0.degree. C. to about
40.degree. C., and suitably over an pressure range within the
container of from about zero to about 1.2 MPa gauge (175 psig),
i.e. covering the maximum ranges of temperature and pressure
required for carbonated beverages. Suitably, the assembly provides
at least two such circumferential seals, suitably over the whole of
the above temperature and pressure ranges.
[0048] Embodiments of the present invention will now be described
further by way of example with reference to the accompanying
drawings, in which:--
[0049] FIG. 1 shows a comparative view of a container neck (in
elevation) and a closure (in cross section) secured to the neck in
a sealing position, wherein the left side of the closure is shown
with a prior art sealing liner and the right side of the closure is
shown with a sealing arrangement in accordance with the present
invention;
[0050] FIG. 2 shows a detailed longitudinal view partially in
cross-section of the operative region of a container closure
assembly according to the present invention from FIG. 1, with the
closure unscrewed from the container neck;
[0051] FIG. 3 shows a detailed longitudinal view partially in cross
section of the operative region of a container closure assembly
according to the present invention from FIG. 1, with the closure
shown in the closed and sealing position the container neck;
[0052] FIG. 4 shows an enlarged partial longitudinal sectional view
through the sealing region of the container closure according to
the embodiment of FIGS. 2 and 3;
[0053] FIG. 5 shows a partial longitudinal sectional view similar
to that of FIG. 4 through the sealing region of a closure according
to a further embodiment of the invention;
[0054] FIG. 6 shows a partial longitudinal sectional view similar
to that of FIG. 4 through the sealing region of a closure according
to a further embodiment of the invention;
[0055] FIG. 7 shows a partial longitudinal sectional view through
the sealing region of the closure according to a further embodiment
with the closure disengaged from the container neck;
[0056] FIG. 8 shows a partial longitudinal sectional view through
the embodiment of FIG. 7 with the closure fully secured on a
container neck (shown in phantom); and
[0057] FIG. 9 shows a view of a further assembly according to the
present invention with a container neck (in elevation and partially
in cross-section) and a closure (in cross section) secured to the
neck in a sealing position.
[0058] Referring to FIG. 1, the assembly comprises a container neck
1 and a closure 2. The closure 2 comprises a base 3 and an outer,
threaded skirt 4. The container neck 1 terminates in a rounded,
smooth-surfaced lip 5. In prior art closure assemblies, this lip
forms a pressure-tight seal with an elastomeric liner 6 shown
hatched in the "prior art" portion of FIG. 1.
[0059] The container neck 1 is formed from polyethylene
terephthalate (PET) by injection molding. The closure 2 is likewise
molded in one piece by injection molding from polyethylene. The
neck 1 and closure 2 are provided with integrally molded,
fast-turn, steeply-pitched threads incorporating a pressure safety
feature, as described in detail in our International patent
application EP-A-1446332, the entire content of which is expressly
incorporated herein by reference.
[0060] Briefly, on the inside of the skirt portion 16 there is
provided a four-start first screw thread made up of four first
thread segments each made up of two portions 10,11, as shown in
phantom on FIG. 1. The thread segments extend a total of about 170
degrees around the skirt, whereby adjacent thread segments overlap
around the circumference of the skirt. A substantially continuous,
approximately helical thread gap is defined between overlapping
regions of the first thread segments on the skirt 4.
[0061] The container neck 10 is provided with a second screw thread
formed from four short second thread segments 8, each of which is a
substantially continuous helical thread extending about 20 degrees
around the container neck.
[0062] An important feature of this assembly is the profiling of
the upper surface of the thread segments on the closure skirt,
which is described in more detail in EP-A-1446332.
[0063] The thread segments on the closure skirt also include a
pressure safety feature similar to that described and claimed in
our International Patent Publication WO95/05322. Briefly, a step 9
is provided in the upper surface of the thread portion 11 to abut
against an end of the neck thread segments 8 and block unscrewing
of the closure 2 from the neck 1 when the neck thread segments 8
are in abutment with the upper surface of the skirt threads, i.e.
when there is a net force on the closure in an axial direction out
of the container neck. This abutment acts to block further
unscrewing of the closure until venting of gas pressure from inside
the container is substantially complete, so that the closure can
drop down to bring the thread 8 out of abutment with the step 9. A
region of the upper surface of the skirt thread segments 11
situated adjacent to the step 9 has a low pitch of about 6 degrees
to reduce the risk of the pressure safety feature being over-ridden
by high pressure inside the container.
[0064] The container and closure assembly is also provided with
complementary locking elements on the container neck and the
closure to block unscrewing of the closure from the fully engaged
position on the container neck unless a minimum unscrewing torque
is applied. These locking elements comprise four equally radially
spaced locking ribs 13 on the inside of the closure skirt 16, and
four equally radially spaced retaining ramps on the container neck.
The ramps have a radially sloped outer face 12 and a radially
projecting retaining edge 14 against which the rib 13 on the
closure abuts when the closure is fully engaged on the container
neck. The complementary locking elements may be as described in our
International Patent Publication WO91/18799, the entire content of
which is hereby expressly incorporated by reference. The
complementary locking elements signal to the user by means of an
audible "click" when the sealing position has been reached. The
complementary locking elements resist "backing-off" of the closure,
which is especially advantageous for the steeply pitched threads
when the contents of the container are pressurized.
[0065] The skirt thread portions 10 are provided at one end with an
upwardly projecting a stop shoulder 18 forming a first stop against
which an end of the neck thread segments 8 may abut, thereby to
block over-tightening of the closure on the neck.
[0066] The container closure assembly also comprises a
tamper-evident safety feature. The safety feature includes a
tamper-evident ring 15 that is initially formed integrally with the
skirt 4 of the container closure 2 and joined thereto by frangible
bridges. The tamper-evident ring 15 comprises a plurality of
integrally formed, flexible, radially inwardly pointing retaining
tabs 16. A circumferential retaining lip 17 is provided on the
container neck 1.
[0067] Referring to FIGS. 2 and 3, the closure comprises a
cylindrical sealing plug 24. The closure further comprises a
cylindrical sealing skirt 20 that is substantially concentric with
and equal in height (measured from the base of closure) to the
sealing plug. The sealing plug 24 and the sealing skirt 20 are
concentric with the threaded skirt 4 and located inside the
threaded skirt 4 for sealing abutment against opposite sides 25,29
of the container neck proximate to the container lip 5.
[0068] The sealing skirt 20 has two small circumferential sealing
ribs 21,22 of substantially triangular cross-section on a radially
inner side thereof. The cylindrical sealing plug has two
circumferential sealing ribs 26,27 provided on a radially outer
surface of the sealing plug 24, the dimensions of the
circumferential sealing ribs 26,27 being the same or similar to
those of sealing ribs 21,22 on the sealing skirt. The
circumferential sealing ribs 26,27 are located at substantially the
same heights respectively above the base of the closure 2 as the
respective circumferential sealing ribs 21,22 on the sealing skirt
20.
[0069] The circumferential sealing ribs on the sealing plug and the
sealing skirt have a substantially equilateral triangular
cross-section, and are approximately 150 micrometers high, in the
unstressed state. However, they deform when pressed against the
harder material (glass or PET) of the container neck to form the
pressure-tight seal. The small dimensions of the sealing ribs
enable a pressure tight seal to be achieved without substantial
force having to be applied to the sealing plug to form the
seal.
[0070] In use, the closure is secured on the container neck as
shown in FIG. 3, Both the sealing skirt 20 and the sealing plug 24
are radially slightly flexible to engage the sealing lip. The
circumferential sealing ribs on the sealing skirt and the plug
engage opposite sides 25,29 of the sealing lip 5, and pinch the lip
between them at two vertically spaced locations to form a highly
effective seal by concentrating pressure at the sealing ribs. The
upper sealing ribs 22,27 provide a pinch across the rounded lip 5
of the container neck, thereby substituting for the flexible
sealing fins that are described in WO02/42171.
[0071] Referring to FIG. 4, the sealing region of the closure is
shown in more detail. It can be seen that the sealing skirt 20 is
provided with two circumferential sealing ribs 21,22 on a radially
inner surface thereof that are substantially triangular in
cross-section. In addition, the bottom 30 of the sealing skirt 20
is profiled to form a further circumferential sealing rib 31 for
applying concentrated force to a the outside surface 25 of the
container neck proximate to the lip 5 to effect a seal. The bottom
of the sealing plug 24 is provided with an exactly corresponding
further circumferential sealing rib 32 spaced at the same
longitudinal distance above the base of the closure as the
corresponding feature on the sealing skirt, for applying a further
pinch across the container neck. The overall effect is to provide a
substantially symmetrical sealing jaw for gripping the top of the
container neck.
[0072] Referring to the embodiment of FIG. 5, the sealing skirt and
the sealing plug are profiled in similar fashion to the embodiment
of FIG. 4 to form a jaw for sealing against the upper part of the
container neck proximate to the container lip. However, the jaw
profile is slightly different, such that the angle of the further
circumferential sealing ribs 37,39, at the bottom of the sealing
skirt and the sealing rib respectively, is more obtuse. This
profile of the further circumferential sealing ribs 37,38 may be
preferable for certain container neck profiles, and may also offer
certain advantages for ease of molding of the closure.
[0073] Referring to FIG. 6, the sealing skirt and the sealing plug
are profiled in similar fashion to the embodiment of FIG. 4 to form
a jaw for sealing against side walls of the container neck
proximate to the container lip. However, the jaw profile is
slightly different, such that the angle of the further
circumferential sealing ribs 42,44, at the bottom of the sealing
skirt and the sealing rib respectively, is more acute. This profile
of the further circumferential sealing ribs 42,44 may be useful to
apply a high, localised sealing pressure at the points where the
further sealing ribs contact opposite sides of the container
neck.
[0074] Referring to FIG. 7, the principal features of the container
neck and closure are as described above in relation to the
embodiment of FIGS. 2 and 3. In particular, the closure 50 has an
outer, threaded closure skirt 51 for engagement with complementary
threads on the container neck 60. The closure of FIG. 7 further
comprises a cylindrical sealing skirt 52 concentric with the
threaded skirt 51 and located slightly inside the threaded skirt 51
for sealing abutment against outer surface of the container neck
proximate to the container lip. The sealing skirt 52 has two small
circumferential sealing ribs 54,55 of substantially triangular
cross-section and height approximately 100 micrometers on a
radially inner side thereof.
[0075] The container closure 50 in the embodiment of FIG. 7 further
comprises a cylindrical sealing plug 53 that is substantially
concentric with and equal in height (measured from the base of
closure) to the sealing skirt 52. Two circumferential sealing ribs
56,57 are provided on a radially outer surface of the sealing plug,
the dimensions of the circumferential sealing ribs 56,57 being the
same or, similar to those of sealing ribs on the sealing skirt. The
circumferential sealing ribs on the sealing skirt and the sealing
plug are located at substantially the same heights above the base
of the closure, respectively.
[0076] In addition, the closure in the assembly of FIGS. 7 and 8
comprises two sealing fins 58,59 in the form of relatively
thin-walled cylindrical projections extending from the base of the
closure 50 concentric and intermediate the sealing skirt 52 and the
sealing plug 53. The height of the sealing fins 58,59 above the
base of the closure is approximately half the height of the sealing
skirt and the sealing plug.
[0077] In use, the closure is secured on the container neck as
shown in FIG. 8. Both the sealing skirt 52 and the sealing plug 53
are radially slightly flexible to engage the lip of the container
neck 60. The circumferential sealing ribs on the sealing skirt and
the plug engage opposite sides of the neck proximate to the lip of
the neck, and pinch the lip between them at two vertically spaced
positions to form a highly effective seal by concentrating pressure
at the sealing ribs. In addition, the sealing fins 58,59 abut
against the container lip intermediate the sealing skirt and the
sealing plug to form a further seal.
[0078] Referring to FIG. 9, the principal features of the container
neck and closure are as described above in relation to the
embodiment of FIGS. 2 and 3, and will not be described again. The
assembly of FIG. 9 differs principally in the construction of the
locking elements to resist unscrewing (backing off) of the closure
when it is in the closed and sealing position.
[0079] Briefly, the locking elements comprise four equally radially
spaced first locking projections 62 on the container neck 63, and
four equally radially spaced second locking projections 64 on the
inside of the closure skirt 65. The projections 62 on the container
neck are located below the short neck thread segments 66, where
they are least noticeable to a person drinking directly from the
container neck. The locking projections 64 on the closure skirt 65
are located level with, and radially spaced by about 2 mm from, the
bottom of the threads 68 on the skirt. The locking projections 64
on the closure skirt form a continuation of the helical thread path
defined by closure threads 68, whereby the short thread segments 66
on the neck can pass smoothly past the locking projections 64 on
the closure as the cap is secured on the neck.
[0080] Each of the locking projections 62,64 is substantially in
the form of a triangular prism having its long axis aligned with
the axis of the closure assembly. The height of each locking
projection is about 1.5 mm, and the base width is about 1.5 mm.
This ensures that the projections have sufficient strength to snap
over each other without permanent deformation.
[0081] Each of the thread segments 68 on the closure skirt includes
a longitudinally upwardly projecting portion 70 that defines a
longitudinal stop surface against which a second end of one of the
short thread segments 66 on the neck may abut when the closure is
fully secured on the neck to block over-tightening of the closure
on the neck.
[0082] The sealing arrangement in the assemblies according to the
present invention enables the closure to be secured and resecured
on the container neck without the need for high torque or low
pitched threads to force a seal. It can be seen that the assembly
according to the invention provides at least two circumferential
seals having a high sealing pressure over the whole range of
temperature and pressure normally encountered in carbonated
beverage containers. It can further be seen that the closure is
suitable for application to container necks having rounded top
lips, such as glass container necks and plastic container necks
having a rounded lip to assist drinking directly from the neck. The
drawbacks associated with the use of soft sealing liners in the
closure cap are eliminated, in particular the closures according to
the present invention can be resecured on the container
neck-repeatedly, without damage or loss of effectiveness.
[0083] The above embodiments have been described by way of example
only. Many other embodiments falling within the scope of the
accompanying claims will be apparent to the skilled reader.
* * * * *