GB2347926A

GB2347926A - Cap and/or neck with deformable side wall

Info

Publication number: GB2347926A
Application number: GB9906221A
Authority: GB
Inventors: Randall Julian
Original assignee: Rexam Containers Ltd
Current assignee: Nolato Jaycare Ltd
Priority date: 1999-03-19
Filing date: 1999-03-19
Publication date: 2000-09-20
Also published as: GB9906221D0

Abstract

A container neck and cap combination includes a cylindrical side wall 9 on either the neck 4 or cap 2 which has a first screw thread 10 whose surface 14 has an angle of inclination of at least 60 degrees, the first screw thread cooperating with a second screw thread on the other of the neck or cap, the two threads slipping on each other and the side wall being deformable when the cap is rotated past the point when it seals the container neck. The first and second screw threads may have the same angle of inclination which may be 65 degrees. The cap may have a non-circular skirt 12 surrounding its cylindrical side wall 9, the combination ensuring adequate sealing when a non-circular cap is rotated to a predetermined orientation.

Description

CONTAINER AND CLOSURE CAP The invention relates to a container and closure cap therefor and in particular relates to a container and closure cap of the type in which the cap is screwed onto the container to a predetermined rotational orientation relative thereto.

It is frequently desired, typically for aesthetic reasons but also for some child resistant closure latch mechanisms, to design threaded closures and containers with non-round shapes or otherwise irregular protrusions intended to sit in alignment with respect to each other when the package is in the closed and sealed position. One example would be square shaped jars and caps for skin creams or other personal care products. Another includes oval shaped double wall screw caps designed to lock onto oval child resistant containers for medicines and other hazardous consumer products.

Due to minor variations in thread and sealing lip dimensions resulting from mass production tooling and processes, closure orientation may vary by as much as 20 to 100 degrees relative to the container body when screwed on and tightened to a particular sealing force. Conversely, when such closures are screwed on to an orientation stop, the sealing force may vary from zero to an unacceptably high value.

While there are many dimensions that can vary to cause the problem, the net result of any combination of variations may be measured as a variation in the vertical dimension between the inside roof of the closure and the sealing lip on the bottle when the cap is brought to a particular orientation and stopped.

In the past, closures have been designed to overcome this problem by means of a special sealing feature designed to telescope vertically with a cooperating feature on the container neck, such as tight fitting plug sized to seal the bore of the container neck over a range of depths of insertion. However, in many cases this technique will not work for lack of a smooth controlled diameter on the bottle to seal against.

In other instances closures have been designed to use a gasket resilient through an appropriate range of compressibility to take up the variation and provide sealing pressure within a suitable range. However, it is frequently desired to use only a thin film glued or heat sealed across the mouth of the container in place of a resilient gasket so as to provide tamper evidence, improved barrier properties and reduced cost.

The stop to which such closures are tightened to provide alignment with the container may be either or both of two general configurations. In the first instance, a radial stop on the neck of the container is configured to interact with a cooperating stop, either at the thread tail-out or on the skirt of the closure. In other cases, the stop is implemented as the lower extremity of the closure skirt comes into the vertical contact with a specially configure (squared off) shoulder on the container. The latter is frequently used to eliminate any unsightly gap between the skirt of the closure and the shoulder of the container. Again, in both cases, the positioning of the closure against any surface other than the sealing surface creates a variability in the pressure exerted against the sealing surface and results in either over-tightened closures, which are difficult to remove, or loose closures which are not well sealed to the container.

In US 3894647 a container and closure cap are described in which the cap is screwed onto the container to a predetermined rotational orientation defined by a stop. The cap is formed with a tubular skirt connected to a disc-like top through a resilient annular shoulder portion which flexes to compensate for tolerance variations in the threads of the cap and container neck in order to ensure that the cap liner seals the neck of the container. The flexing of the annular shoulder causes an unsightly distortion and may even leave visible stress marks.

The present invention seeks to improve on the prior art and provides a container and closure cap therefor comprising: a container having an open-ended and externally screw threaded cylindrical neck; and a closure cap having a cylindrical side wall with an internal screw thread adapted to cooperate with the thread on the container neck and a planar end wall adapted to form a seal with the open end of the container neck; wherein at least one of the opposing surfaces of the screw threads on the cap and the container neck is inclined to the plane perpendicular to the axis of the neck of the container at an angle of at least 60 and both screw thread surfaces have sufficient lateral extent, that the screw threads can slip laterally on one another to enable the side wall of the cap or the neck of the container to deform when the cap is tightened onto the container to a particular predetermined rotational orientation relative thereto which is rotationally beyond the point at which the end wall of the cap forms a seal with the open end of the neck.

Embodiments of the invention are described below with reference to the accompanying drawings in which: Figure 1 is an isometric view of a container with a closure cap fitted; Figure 2 is a partial cross sectional view taken on the line II-n in Figure 1 with the cap loosely applied to the container; Figure 3 is a view similar to that of Figure 2 but with the cap tightly applied to the container; and Figure 4 is a view corresponding to that of Figure 3 but showing an alternative container and cap.

A generally rectangular container 1 is shown in Figure 1 having a generally rectangular closure cap 2. As seen from Figure 2 the container has a body 3 and a cylindrical neck 4 connected to the body by a shoulder 5. The neck has an open end 6 and is provided with an external screw thread 7.

The cap 2 has a planar end wall 8 and a cylindrical side wall 9 which is provided with an internal screw thread 10. The threads 7 and 10 are adapted to enable the cap to be screwed onto the container so that the end wall 8 can form a seal with the open end 6 of the neck 4. A cap liner 11 is provided to enhance this seal.

The cap is also formed with a skirt 12 which has a rectangular cross section corresponding to that of the container 1 and surrounds the cylindrical side wall.

The opposing surfaces 13 and 14 of the screw threads are both inclined at an angle a to the plane parallel to the axis of the neck 4 of the container. The angle of inclination is preferably at least 60 . More preferably it is about 60 - 75 in the case of a container and cap made of thermoplastic materials, the most preferred angle is 65 . In the case of a container and cap made of metals, the angle of inclination is preferably about 70 -80 .

When the cap is tightened onto the container to a predetermined rotational orientation defined by the aligned position shown in Figure 1, it passes through the loose position shown in Figure 2 to the tight position shown in Figure 3. Here it can be seen that the aligned position has been achieved after an initial seal has been made between the end wall 8 of the cap and the open end 6 of the container and further tightening of the cap to the aligned position has caused the screw threads 7 and 10 to slip laterally on one another causing the cylindrical side wall to deform by bulging outwardly. The degree of slipping and consequent bulging will vary according to manufacturing tolerances. It will be appreciated that the screw thread surfaces must have sufficient lateral extend that they can slip laterally on one another without becoming disengaged and jumping over one another.

In a modified embodiment shown in the tightened condition in Figure 4, only the surface 13 of the screw thread on the container neck is inclined. In this embodiment it is the neck of the container which is adapted to bulge inwardly when the opposing surfaces of the threads 7 and 10 slip laterally on one another.

The outer skirt is omitted in this embodiment since the container is cylindrical rather than generally rectangular.

Claims

CLAIMS 1. A container and closure cap therefor comprising: a container having an open-ended and externally screw threaded cylindrical neck; and a closure cap having a cylindrical side wall with an internal screw thread adapted to cooperate with the thread on the container neck and a planar end wall adapted to form a seal with the open end of the container neck; wherein at least one of the opposing surfaces of the screw threads on the cap and the container neck is inclined to the plane perpendicular to the axis of the neck of the container at an angle of at least 60 and both screw thread surfaces have sufficient lateral extent, that the screw threads can slip laterally on one another to enable the side wall of the cap or the neck of the container to deform when the cap is tightened onto the container to a particular predetermined rotational orientation relative thereto which is rotationally beyond the point at which the end wall of the cap forms a seal with the open end of the neck.
2. A container and closure cap as claimed in Claim 1, wherein at least one of the opposing surfaces of the threads on the cap and the container neck is inclined to the plane perpendicular to the axis of the neck by at least 60 -75 .
3. A container and closure cap as claimed in Claim 1 or Claim 2, wherein the opposing surfaces of the threads on the cap and the container neck are parallel to one another and are inclined to the plane perpendicular to the axis of the neck by about 65 .
4. A container and closure cap as claimed in any preceding claim, wherein a skirt surrounds the cylindrical side wall of the closure cap.
5. A container and closure cap as claimed in any preceding claim, wherein the cylindrical side wall of the closure cap is adapted to bulge outwardly when the opposing surfaces of the threads slip laterally on one another.
6. A container and closure cap as claimed in any one of Claims 1-4, wherein the neck of the container is adapted to bulge inwardly when the opposing surfaces of the threads slip laterally on one another.
7. A container and closure cap substantially as described herein with reference to the accompanying drawings.