CLOSURES FOR CONTAINERS SUCH AS BOTTLES AND JARS FIELD OF THE INVENTION THIS INVENTION relates to closures for containers such as bottles and jars. BACKGROUND TO THE INVENTION

Glass and plastic containers for beverages, sauces, jams, pickles etc are usually considered to fall into two categories. These are narrow mouthed containers meaning bottles with mouth diameters of, for example, 20 to 40mm and wide mouth containers meaning jars with mouth diameters of, for example, 40 to 100mm.

Wide mouth containers are usually closed by screw-on closures in the form of lids. Less frequently snap-on closures of polyethylene (high or low density) are used.

There are vast numbers of people who have poor eyesight and for whom reading and writing is difficult. The cost of eye tests and the purchase of prescription glasses is beyond the means of many of these people. For some, even the cost of reading glasses is beyond their means.

The present invention overcomes the difficulties outlined in the previous paragraph by providing lenses which are incorporated into a closure for a container.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the present invention there is provided a transparent screw- on closure for a container which comprises a cylindrical skirt having screw threading on the inside surface thereof and a disc-like end wall, part of the end wall being configured so that said part forms a magnifying lens. In one embodiment of the invention said part is in the form of a disc joined along its periphery to the remainder of the end wall. Preferably said part has a circular periphery. Said periphery can be joined to said remainder of the end wall along a line of weakening which facilitates separation of the lens from said remainder of the end wall.

In this form the injection points or points of the mould lead into that part of the mould cavity in which the skirt is moulded. In another form the closure is formed with two thickened areas which form two half- moon shaped lenses. In this form the injection point of the mould can be at the centre of the end wall, and the thickened areas can be one on each side of the blemish left at the injection site. Alternatively, in this form, the injection point or points can be into the part of the mould cavity in which the skirt is moulded.

The screw threading can be continuous or can comprise a number of discrete thread sections spaced around the inside surface of the skirt.

The skirt can be thicker along the free edge portion thereof than it is between the free edge portion and the disc-like end wall.

It is preferred that the closure is moulded using PET (polyethylenetetraphthalate) or a PET copolymer or a mixture of PET and a PET copolymer. There can be a circular rib on the underside of the disc-like end wall, the rib being inwardly of the skirt and defining, between itself and the skirt, an annular recess for receiving a seal.

There can be a rim around the periphery of the disc-like end wall, the rim standing proud of that surface of the disc-like end wall that is remote from the sleeve. The rim can be circumferentially continuous, or can consist of a series of discrete sections with gaps between them. The closure is preferably injection moulded but it can be compression moulded.

When PET, a PET copolymer or a mixture of PET and a copolymer is used, the method of manufacturing the closure can comprise screwing it onto an externally threaded container the temperature of which has been raised by filling it with produce at an elevated temperature whereby the closure is heated to a temperature of between 75 and 1 10 degrees centigrade, preferably between 90 and 1 10 degrees centigrade thereby to stabilise the closure.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which:- Figure 1 is a pictorial view of the underside of a closure in accordance with the present invention;

Figure 2 is a pictorial view similar to that of Figure 1 and showing a closure with a tamper band;

Figure 3 is a side elevation of the closure of Figure 2;

Figure 4 is a section illustrating the closure of Figure 1 screwed onto a jar; and Figures 5 to 8 are views identical to those of Figures 1 to 4 but illustrating a further form of closure.

DETAILED DESCRIPTION OF THE DRAWINGS

The closure illustrated in Figure 1 is designated 10 and comprises a cylindrical skirt 12 and a disc-like end wall 14. On the inside of the skirt 12 there are discrete thread sections 16 which are compatible with a continuous screw thread T on the outside of the jar J (Figure 4) and adjacent its open mouth. The threading can, however, be continuous. The closure can be of PET or a PET copolymer or a mixture of PET and a PET copolymer.

The closure can be injection moulded or compression moulded. It is preferred that the closure include not less than 30% of the copolymer. It is further preferred that the copolymer be present in amounts exceeding 50% or 75% and in some circumstances it is preferred that the closure be injection moulded using only the copolymer. On the outside of the skirt 12 there are circumferentially spaced, rectangular raised areas 18 which facilitate gripping of the closure when it is to be screwed onto, or unscrewed from, the jar J. The provision of these areas has the result that, considered circumferentially, the skirt has alternating thicker and thinner wall portions. At its rim the skirt is thicker than it is over the remainder of its height. This is achieved by moulding the skirt with a bead 20 (see Figure 4) of rectangular cross-section. The thickened rim portion of the skirt 12 prevents flaring of the skirt.

A circular rib 22 is moulded onto the underside of the disc-like end wall 14 of the closure. The rib 22 is inwardly of the skirt 12 and defines therewith a recess 24, which, in use, faces downwards and which receives a seal 26. The seal 26 presses onto the edge of the jar which bounds the mouth of the jar J (see Figure 4). The closure of Figures 2 and 3 differs from that of Figure 1 in that it has a tamper band 28 secured to the rim of the skirt 12 by bridges 30. The band 28, after the closure has been fitted to the jar, is heated so that it shrinks and is under the bead B. The band can be shrunk by the heat of a heat shrink tunnel through which the jar and container pass, by moving past infrared heaters or by the application of an ultrasonic horn the vibrations of which heat the band 28.

Should an attempt subsequently be made to soften the band 28 by heating it, the PET constituting the band discolours thereby revealing tampering. The bridges 30 fail when the closure is first unscrewed from the jar.

Two parts of the end wall 14 in Figures 1 to 4 are thicker than the remainder of the end wall 14 and are configured to form two half moon magnifying lenses 32 which are consequently integral with the remainder of the end wall. The point at which injection of plastics material into the mould took place is designated 34 in Figure 1 and is between the lenses 32. The cross-sectional configuration of the lenses 32 is best seen in Figure 4.

In Figures 5 to 8 the end wall is thickened to form a single circular magnifying lens 36 the configuration of which is best seen in Figure 8. The injection points of the mould are in the part of the mould cavity which defines the skirt 12. This is to avoid an injection point at the centre of the lens 36.

To enable the lenses 32, 36 to be used for reading purposes, they are detached from the remainder of the end wall. To facilitate this grooves are moulded into the end wall 14. In Figures 1 to 4 the groove is designated 38 and extends between and around the two half-moon lenses 32. In Figures 5 to 8 there is a circular groove designated 40 which encircles the lens 36. The grooves 38 and 40 form lines of weakening which enable the circular part of the end wall to be sucked into a container as it cools after filling thereby to form a tamper evident feature. On first opening of the container the partial vacuum is broken and the circular part of the end wall "pops up". This reveals that the container has been opened. To inhibit scratching of the lenses, the flat top surface of the end wall is formed with a circular rib 42. When containers are stacked the rib 42 minimises contact between the base of an upper container and the end wall 14 of the closure of a lower container.