[0001] This invention relates to a closure cap for closing a container under vacuum,comprising
a circular closing disc having a flanged edge, a sealing compound provided therein,
and a sealing ring of synthetic plastics material of L-shaped cross-section, and including
an edge directed radially inwardly and forming an abutment for the circular closing
disc and a substantially cylindrical skirt enclosing the flanged edge of the circular
closing disc, said skirt having on its inside radially inwardly directed projections
adapted to engage underneath the thickened edge of a container to be sealed, and the
sealing ring being further provided with a guaranty construction.
[0002] A cap of this type, which is sometimes referred to as a vacuum snap cap, is disclosed
in Dutch patent application 7407362. In this prior cap, the guaranty construction
is formed by a tear-off guaranty ring provided at the bottom of the skirt, which ring
is fitted with a pull tab projecting radially outwardly of the cap, and with which
the cap can be opened without any tool being required. The tear-off guaranty ring
forms an undesirable extension of the skirt of the sealing ring, and the radially
projecting pull tab impedes the automatic supply of sealing rings via a sealing-ring
hopper, since sealing rings thus designed continually become jammed in the hopper.
It is true that after the sealing ring has been torn off, the cap can be reused for
closing containers provided with only one thickened edge, but they are not suitable
for re-closing jars, i.e. containers provided with a double thickened edge, as are
usually employed for the vacuum preservation of foodstuffs. The lower edge of the
skirt in such containers or jars should be in sealing contact with the second thickened
edge of the container, which is not the case with the prior cap.
[0003] It is an object of the invention to provide a cap of the above described type that
can be used for re-closing containers having a double thickened edge, with avoidance
of the drawbacks going with the above described guaranty construction.
[0004] To this effect the invention provides a cap in which the guaranty construction comprises
a tiltable tear-off disposed within the standard height of the skirt of the sealing
ring, which tear-off tab is connected to the skirt by means of two tear lines extending
in axial direction of the skirt.
[0005] In order that,when a container is re-closed, the closure may be insect infection-proof,
the sealing ring adjacent the tear-off tab is made double-walled, with an outer wall
being formed by the tear-off tab itself and an inner wall constituting a continuous
extension of the lower edge of the skirt.
[0006] For the purpose of rendering it difficult for the cap to be opened otherwise than
via the tear-off tab, the lower edge of the skirt is preferably bevelled inwardly.
In this manner there is no proper grip on the cap except at the tear-off tab. In order
that there may be a proper grip on the cap at the tear-off tab, the tear-off tab extends
radially slightly beyond the peripheral edge of the skirt and the tear-off tab is
provided at the bottom with a nail edge. In order to facilitate the tilting of the
tear-off tab, the wall thickness of the skirt at said tab
"i.s thinner than the rest of the skirt.
[0007] For reducing the chance of vacuum leaks in the vacuum-sealed containers,the radially
inwardly directed edge of the sealing ring is preferably stepped, with the inner-most
edge portion being off-set in axial direction towards the centre plane through the
skirt and parallel to the plane through the upper edge of the skirt. In this manner
there is formed a mechanical buffer for absorbing shocks that might result in vacuum
leaks.
[0008] One embodiment of the snap cap according to the invention will now be described,
by way of example, with reference to the accompanying drawing, wherein:
Fig. 1 is a top view of the sealing ring;
Fig. 2 is a front elevational view of the sealing ring;
Fig. 3 is a cross-sectional view taken on the line III-III of Fig. 1;
Fig. 4 is a bottom view of the sealing ring;
Fig. 5 shows a detail of the sealing ring on an enlarged scale;
Fig. 6 illustrates a portion of a jar rim with a part of a snap cap according to the
invention thereon at the position of the tear-off tab;
Fig. 7 a cross-sectional view similar to Fig. 6 at a position beyond the tear-off
tab.
[0009] The sealing ring 1 (see Figures 1-5) has an L-shaped cross-section, the one leg of
which is formed by the skirt 4, substantially of cylindrical shape and the other leg
by the radially inwardly extending edge 3, forming an abutment for a closing disc
18 usually made of metal (see Figs. 6-7). Provided in the wall of the skirt 4 is a
tear-off tab 2 which is connected through tear lines to the wall of the skirt 4. The
tear lines 6 extend only along a part of the height h of the sealing ring. Above the
tear-off tab 2 the wall thickness 7 of the skirt 4 is thinner, so that the tear-off
tab 2 is adapted for tilting movement,as will be explained in the following. The lower
edge 5 of the skirt 4 is bevelled inwardly in order to thus reduce the grip on the
cap beside the tear-off tab 2.
[0010] Provided on the inside of the skirt wall are projections 8, directed radially inwardly
and uniformly distributed over the skirt's circumstance.These projections 8 have a
triangular cross-section and are adapted to engage underneath an outwardly thickened
edge of a container to be sealed.
[0011] Fig. 5 shows the construction of the sealing ring 1 at the position of the tear-off
tab 2 on an enlarged scale. The top face 23 of the sealing ring 1 is stepped to cause
the thrust face 24 of the edge 3 to be off-set towards the centre plane through the
skirt 4. There is thus formed a chamber 9 which serves as a mechanical buffer for
absorbing shocks on the edge, so that the risk of vacuum leaks is substantially reduced.
At the position of the tear-off tab 2 wall 7 is thinner than the normal wall thickness
of the skirt, the difference in thickness being indicated by reference numeral 10.
The top side of the tear-off tab 2 has a bevelled face 14, so that when a force F
is exerted on the tear-off tab 2, said tab will tilt about the tilting line 11, until
the bevelled face 14 comes to abut against the thinned wall portion 7. During the
tilting of the tear-off tab 2, the tear lines 6 through which the .tear-off tab 2
is connected to the skirt 4 are broken. Accordingly it can be verified whether a container
closed by means of a snap cap according to the invention has actually remained closed.
At the bottom of the tear-off tab 2 there is provided a recess 13 designed as a nail
edge in order to provide a better grip on the tear-off tab 2. Adjacent the tear-off
tab 2 the skirt 4 is double-walled. The inner wall 12 is,in axial direction, a continuous
extension of the thinned wall 7 and in circumferential direction a continuous extension
of the wall of the skirt 4. During the tilting of the tear-off tab 2 about the tilting
line 11 no force whatever is exerted on the inner wall 12, so that this retains its
original shape.
[0012] Figures 6-7 show the snap cap according to the invention disposed on a jar-type container
to be sealed. The jar has a glass wall 15 with two thickened rims respectively designated
by numerals 16 and 17. The snap cap comprises a disc 18 usually of metal, and profiled
for strengthening. The closing disc 18 is provided with a flange 19, and a sealing
compound 20 is provided at the inner side of the closing disc 18, to provide a vacuum-tight
seal on the upper rim 16 of the glass wall 15. The closing disc 18 is pressed on the
jar's wall 15 by means of the sealing ring 1, whereby the radially inwardly directed
edge 3 comes to lie in contact with the' closing disc 18, while the inwardly directed
projections 8 engage underneath the upper thickened rim 16 of the glass wall 15. The
upper edge of the sealing ring 1 is stepped to form a buffer space 9.
[0013] In order to render the interspace 22 between the two thickened rims 16 and 17 insect
infection-proof, the bevelled lower edge 5 should, at 25,be in sealing contact with
the outer wall of the thickened rim 17.
[0014] Even after the guaranty structure has been ruptured, i.e. after the tilting of the
tear-off tab 2, the space 22 must remain sealed and this can be achieved by means
of the double-walled form of the skirt 4 of the sealing ring, as shown in Fig. 7.The
inner wall 12 is in surface-to-surface contact with the outer wall of the thickened
rim 17, so that even after the tilting of the tear-off tab 2 a sealing of the space
22 is achieved at the edge 21.
1. A closure cap for closing a container under vacuum, comprising a circular closing
disc having a flanged edge, a sealing compound provided therein, and a sealing ring
of synthetic plastics material having an L-shaped cross-section, and including an
edge directed radially inwardly and forming an abutment for the circular closing disc
and a substantially cylindrical skirt enclosing the flanged edge of the circular closing
disc, said skirt having on its inside radially inwardly directed projections adapted
to engage underneath the thickened edge of a container to be sealed, and the sealing
ring being further provided with a guaranty construction, characterized in that the
guaranty construction comprises .a tiltable tear-off tab (2)disposed within the standard
height (h) of the skirt (4) of the sealing ring (1), which tear-off tab (2) is connected
to the skirt (4) by means of two tear lines (6) extending in axial direction of the
skirt (4).
2. A closure cap according to claim 1, characterized in that adjacent the tear-off
tab (2) the sealing ring (1) is double-walled, with an outer wall being formed by
the tear-off tab (2) and an inner wall (12) forming a contiuous extension of the lower
edge (5) of the skirt (4).
3. A closure cap according to claims 1-2, characterized in that the lower edge (5)
of the skirt (4) outside the tear-off tab is bevelled inwardly.
4. A closure cap according to claims 1-3, characterized in that the tear-off tab (2)
extends radially slightly beyond the peripheral wall of the skirt (4) and is provided
at the bottom with a nail edge (13).
5. A closure cap according to claims 1-4, characterized in that the wall (7) of the
skirt (4) is thinner adjacent the tear-off tab (2).
6. A closure cap according to any one of claims 1-5, characterized in that the radially
inwardly directed edge (3) of the sealing ring (1) has a stepped design, with the
innermost edge portion (3) being off-set in axial direction towards the centre plane
through the skirt (4) and parallel to the plane (23) through the upper edge of the
skirt.