GB2339771A - Closure and container neck combination with deformable screw thread - Google Patents

Description

2339771 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 otherwis e 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 2 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 configured (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 Wbular skirt connectled 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.

3 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 sea] with the open end of the container neck; wherein the screw thread on the cap or the screw thread on the container is flexible and is adapted to deform in the direction of the axis of the container neck when the cap is tightened onto the container to form a seal.

Embodiments of the invention are described below with reference to the accompanying drawings in which:

Figure I is an isometric view of a container with a closure cap fitted; Figure 2 is a partial cross sectional view taken on the line H- H in Figure I 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 cylindrical container I is shown in Figure I having a generally cylindrical closure cap 2. The container and cap are of the type in which the cap is intended to be screwed onto the container to a predetermined rotational orientation to form a seal. 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.

4 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.

As shown in Figure 2, the screw threadIO on the cap is of elongate generally rectangular cross-section having upper and lower surfaces 12 and 13 lying in planes perpendicular to the axis of the neck of the container. By virtue of its shape, the thread is flexible and is adapted to deform downwardly in the direction of the axis of the container neck when the cap is tightened onto the container to form a seal as shown in Figure 3.

Because of the flexibility of the thread 10, the cap can be tightened to a predetermined rotational orientation on the container. The dimensions of the cap and container are set to take account of manufacturing tolerances such that the threads will always be at least slightly deformed when the cap is tightened to the predetermined rotational orientation.

In an alternative embodiment shown in Figure 4, the thread 7 on the container neck is made flexible and deformable.

I i

Claims (5)

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 seat with the open end of the container neck; wherein the screw thread on the cap or the screw thread on the container is flexible and is adapted to deform in the direction of the axis of the container neck when the cap is tightened onto the container to form a seal.

2. A container and closure cap as claimed in Claim 1, wherein the deformiable thread is of elongate rectangular cross-sectional shape and in the undeformed condition is provided with upper and lower surfaces lying in planes perpendicular to the axis of the neck of the container.

3. A container and closure cap as claimed in Claim I or Claim 2, wherein the deformable thread is on the container neck.

4. A container and closure cap as claimed in Claim 2, wherein the deformable thread is on the closure cap.

5. A container and closure cap substantially as described herein with reference to the accompanying drawings.