WO2025057129A1

WO2025057129A1 - A metal safety cap for a jar, bottle or tin

Info

Publication number: WO2025057129A1
Application number: PCT/IB2024/058934
Authority: WO
Inventors: Mark Richard BLAYNEY; Jason Ashley LEHMAN; Michael John Bean
Original assignee: Sustainable Packaging Designs Ltd
Current assignee: Sustainable Packaging Designs Ltd
Priority date: 2023-09-15
Filing date: 2024-09-13
Publication date: 2025-03-20
Anticipated expiration: 2026-03-15

Abstract

A two-part metal safety cap comprises an inner threaded metal cap, which has an internal thread for engaging with a screw thread to seal a container, such as a tin or jar, and an outer cap which surrounds the inner cap. The inner threaded metal cap and the outer cap each have an engagement means which when engaged one with another allow torque to be transferred from the outer cap to attach and remove the inner cap from the container. A retaining device, such as a hem or curled folded portion, retains the inner metal cap within the outer cap whilst permitting the two to rotate freely with respect to one another. Use of electro-magnetic sorting systems are able to temporarily magnetise these metal items enabling them to be removed from the waste stream.

Description

A Metal Safety Cap for a Jar, Bottle or Tin

Field

This invention relates to a safety cap made of metal for a container, more particularly but not exclusively, to a cap for a jar, bottle or tin which might contain medicaments, tablets or items that may be unsafe to young or vulnerable people, such as cleaning chemicals supplied as powders or in solid form.

Background

Some containers, such as those containing medicines, usually require the use of child resistant packaging or child-proof caps. This has previously been achieved by using a two-part cap comprising an inner threaded element, which engages with the screw thread on the container, and an external element which encloses the internal element, and the external element is free to rotate separately in the opening direction unless engaged.

Engagement features, such as toothed inner and exterior elements, enable the inner and outer caps to engage to drive the inner element to open and close the container.

One example of an engagement features requires a specified action (such as pressing down or squeezing the side of the cap) such that the outer cap is then able to drive the internal cap to open the container. Therefore, unless there is combined pushing and twisting, the container cannot be opened which is what prevents young children from accessing contents such as tablets.

Conventionally these caps are typically formed from a food safe synthetic plastics material, such as polyethylene terephthalate (PET), polypropylene, polyvinyl chloride (PVC), polystyrene and polycarbonate.

Polyethylene terephthalate (PET) is non-toxic, light in weight, strong and durable and so has been used for many years with a wide range of contents. However, these synthetic plastics are not easily recyclable, take many thousands of years to degrade, for example in landfill, and cannot easily be incinerated as they give off toxic and noxious fumes. Prior Art

Published Taiwanese patent application TWM 2 677 200 (Huang Huan-Tsai) discloses a metal can lid consisting of an inner lid which in use is placed around a rim of a bottle or can. A rolling machine is used to form a spiral groove to form threads in the lid which converge to close the bottle (or can).

United States patent US 3 797 688 (Porcelli et al) discloses a closure which is essentially formed from a synthetic plastic material and has central spigot with a body which requires further fabrication stages in order to secure the two parts together. A top wall of the outer cap has a central opening into which the spigot (formed on a top wall of the inner cap) extends. The spigot is deformed to form a bead thereby connects the two caps whilst still permitting their relative rotation.

United States patent US 5 370 251 (Buono) describes a child-resistant closure for a bottle made from synthetic plastic material. It has inter-engaging tabs or fingers which are located within lower portion of one part of the cap. Separate features provide engagement on an upper portion.

United States patent application US 2004/0195197 (Miceli et al) disclosures a synthetic plastics moulding which requires a bespoke tab. The inner cap is coaxially positioned and nested within the outer cap such that a row of angular abutments, on the inner cap engage with a row of angular abutments of the outer cap upon rotation of the outer cap in a closing direction.

United States patent application US 2022/0041350 (Berge), discloses a removable cap which includes a silicon product with an overlap having a side engagement. The side engagement mates with an existing closure device on the container using a heat activated adhesive.

International patent application WO 9001451 (Van Blarcom Closures Inc) discloses a tamper-evident child resistant closure device having two sets of teeth: one on each of an inner cap and an outer cap. The sets of teeth engage to enable removal and closure of the device. US 2020/0130901 (KARLL) discloses a three-part cap, for examples as shown in Figure 17. The three-part cap has a smooth metal over cap that encloses two retained elements.

Many of the aforementioned systems and manufacturing processes require additional tooling, additional materials and complex moulding techniques.

In addition, most are formed from synthetic plastics materials or a mixture of different types of materials and so are not readily recyclable.

In many of the aforementioned closure devices, a user is required to remove a tear off tamper-evident strip which is not required by the present invention because it simply fits to a threaded portion of the container and so does not require any additional parts.

The moulding tools and steps required to fabricate these intricate features are expensive and complex. In addition, the child-resistant closure is not easily recyclable. Another aim of the present invention is to provide a child-proof or child resistant cap from a material that is durable, food safe and recyclable.

Standard metal continuous thread caps have no mechanism which requires a combination of actions or forces together with the unscrewing action in order to open the closure. Therefore, simply replacing two-part synthetic plastics caps with a two- part metal cap is impractical because once squeezed laterally, metal deforms plasticly and so does not recover in the same manner as synthetic plastics caps.

An aim of the present invention is to overcome the aforementioned problems.

Summary of the Invention

According to a first aspect of the invention there is provided a two-part metal safety cap for a container includes an outer cap (outer shell) and an inner cap (inner shell) located therewithin, the inner and outer caps both being formed from sheet metal, the outer cap being in the form of a cylinder shell with an open (distal) end and comprising a (top) surface at a proximal end, a side wall protruding therefrom and a curled edge is formed around a rim of the side wall to define a curl, which lies within the open end of the outer cap, and retains the inner cap within the outer cap and wherein the top surface of the outer cap has at least one embossed/debossed (indent) feature; the inner cap being in the form of a smaller diameter cylinder shell, open at its distal end and having a (top) surface at a proximal end and a side wall protruding therefrom, the inner walls of the inner cap including a threaded portion which extend around at least a portion of a rim of the side wall to an opening of the inner cap, the top surface of the inner cap includes at least one embossed/debossed (indent) feature, and the inner cap is located and retained within the open end of the outer cap, such that the top surfaces of the inner cap and the outer cap are adjacent one another, and each of the surfaces is adapted such that when the outer cap is located in the correct orientation with respect to the inner cap, depression of the outer cap causes the embossed/debossed (indent) feature(s) of the outer cap to engage positively with the embossed/debossed (indent) feature(s) of the inner cap and whereby rotation of the outer cap causes consequential rotation of the inner cap, characterised in that a popup button is provided on at least one surface of the outer cap or the inner cap, which in a relaxed state spaces the inner cap from the outer cap and when a user applied force overcomes an over centring force of the pop-up button to depress it, this enables corresponding embossed/debossed (indent) feature(s) on the inner cap to engage with the embossed/debossed (indent) feature(s) on the outer cap and thereby enables coupling of a torque applied to the outer cap to turn the inner cap.

Optionally a plurality of embossed/debossed (indent) feature(s) are provided around a first circular path, on the outer cap, and on a second circular path on the inner cap, the diameter of the second circular two paths being the same.

In some embodiments there are six embossed/debossed (indent) feature(s) which are provided around each of the first and second circular paths. These features are ideally circular although different shaped embossed/debossed features, such as squares or triangles may be used embossed/debossed.

Unlike prior art closure devices, which are in part or wholly formed from a moulded synthetic plastics material, the present invention is formed entirely from sheet metal and so lends itself readily to recycling.

In one embodiment the respective engagement means comprise a raised (or embossed) portion on an exterior surface of the inner threaded metal cap and a corresponding raised (or embossed) portion on an inner surface of the outer cap, so that the respective portions engage one with another when the outer cap is pressed axially towards the inner threaded metal cap.

The current invention is of an over cap formed from either sheet aluminium or tinplate to add a child resistant mechanism, which requires a combination of actions and forces together, to achieve an unscrewing action in order to open a closure of a bottle or jar overcomes the aforementioned problems. Inter-engaging embossed and/or debossed features allow transfer of torque from an outer metal cap to an inner one, so that an over cap, which retains an enclosed inner cap, can normally rotate freely around the inner cap when simply turned. However, when the two caps are aligned and the outer is pressed down and turned, the engagement of the embossed/debossed features on the over cap and inner cap, act to drive the unscrewing of the inner cap from the container.

Creating in combination a child resistant cap made from either sheet aluminium or tinplate together therefore provide a sustainable solution to this specific requirement that has only been able to be achieved using synthetic plastics materials.

Where the degree of engagement is to be selected the respective sizes, depth and edges of the embossed/debossed features help to determine the ease with which the over cap and inner cap engage and therefore allow a degree of difficulty to be designed into the opening requirements to ensure child resistance.

The invention enables standard types of metal continuous thread caps, already designed for use with industry standard container neck sizes and threads, and so eliminates any need for the users to change or develop other tooling or neck forms to allow its use.

In one embodiment the respective engagement means comprise an indented (or debossed) portion on an exterior surface of the inner threaded metal cap and a corresponding indented (or debossed) portion on an inner surface of the outer cap, so that the respective portions engage one with another when the outer cap is pressed axially towards the inner threaded metal cap.

In another embodiment the respective engagement means comprise both an indented (or debossed) portion and a raised (or embossed) portion on an exterior surface of the inner threaded metal cap and both a corresponding indented (or debossed) portion and a raised (or embossed) portion on an inner surface of the outer cap, so that the respective pairs of portions engage one with another when the outer cap is pressed axially towards the inner threaded metal cap.

It is appreciated that both inner and outer caps could each have both embossed and debossed portions or regions. This may assist in evenly spreading an axial load from the outer to the inner cap; help to ensure alignment and so improve engagement of the inner and outer caps, as well as help to reduce wear on different edges of the bossed and debossed portions.

It is appreciated that the debossed portion may be a recess or cut-away portion so as to receive a raised or embossed portion, in a like manner to how a spline, with ridges or teeth, meshes with grooves in a workpiece to transfer torque.

It is appreciated that the different engagement mechanisms may be used, such as friction surfaces which may have a friction lining, engagement means, pips or a rubber coating to increase friction and so improve coupling of torque between the inner and outer caps.

Advantageously a coating is applied to at least one surface of at least one of the caps. The coating is a food grade protective coating and prevents corrosion and ensures the cap is safe for use in food and beverages. Outer surfaces of the cap may also have decorative coatings, coloured lacquers or printed designs for branding and marketing purposes.

In a yet further embodiment, the respective engagement means teeth or serrations may be formed around an exterior edge portion of the inner threaded metal cap and corresponding teeth formed around an inner edge portion of the outer cap, so that the respective portions engage one with another when the outer cap is pressed axially towards the inner threaded metal cap.

Preferably respective engagement means are dimensioned and arranged such that the outer cap aligns with the inner threaded metal cap in a single relative orientation of the two caps. However, optionally, two or more relative orientations may be permitted, for example when there are two or more rotational symmetries defined by the respective engagement means. The outer cap retains the inner threaded metal cap by way of a retaining means which permits relative rotation of the inner threaded metal cap within the outer cap, when both are removed from the container.

Optionally a spacer is provided so that in an undepressed state, the inner and outer caps are urged apart, and rotation of the outer cap does not result in rotation of the inner cap.

Preferably the retaining means is a curl fold formed in the outer cap and/or at least one clip disposed around a rim of the outer cap and/or at least one bead disposed around a rim of the outer cap.

Ideally a portion of the side wall of the outer cap is folded or curled over to retain the inner cap and this provides strength to the outer cap. The inner cap is dimensioned to fit snugly within the outer cap to ensure there is sufficient overlap of the curl which also prevents the inner cap from rattling inside the outer cap as well as retaining it therein.

In some embodiments the outer cap and the inner threaded metal cap are formed from aluminium. Use of electro-magnetic sorting systems are able to temporarily magnetise these items enabling them to be removed from the waste stream.

Alternatively, at least one of the outer cap and the inner threaded metal cap may be formed from a ferro-magnetic material, such as steel which may be tin plated.

Where sealing is required the inner metal threaded cap may include a liner which is a chemically compatible material that is located between the cap and the jar, tin or bottle.

To assist a user a marker or indicator may be provided on the caps which when aligned indicates the caps are positioned for inter-engagement. In some embodiments the indicator may be shaped to resemble either a padlock and key; or arrows which interengage in a predefined orientation to enable torque applied to the outer cap to twist an unscrew the inner metal threaded from the thread on the container.

Advantages of the invention are that it enables a conventional threaded metal cap to be used as the inner threaded cap and thus no modification of existing production and food container filling lines is required. Another advantage is that the producer may use the layout, size, shape or configuration of the indicator for branding purposes, or for displaying a logo, or for indicating other visual information which may relate to the type or nature of the contents of the container.

According to a second aspect of the invention there is provided a method of producing a two-part metal safety cap for a container, the two-part metal safety cap including outer cap portion and an inner cap portion, comprising the steps of: a) forming an outer cap (or shell) from sheet metal by one or more pressing/stamping steps, the outer cap (or shell) including a top surface, b) forming an embossed/debossed (indent feature) in the top surface of the outer cap (shell), c) forming an inner cap (or shell) portion from sheet metal by one or more pressing/stamping steps, the inner cap (shell) including a top surface, d) forming an embossed/debossed (indent feature) in the top surface of the inner cap portion, e) forming a pop-up button on at least one surface of the outer cap or the inner cap, which in a relaxed state spaces the inner cap from the outer cap; f) press fitting the inner cap into the outer cap portion; and g) forming a curl around a lower edge of the outer cap by folding, rolling or pressing the lower edge whereby the inner cap is retained by its rim engaging with the curl of the lower edge of the outer cap.

Other aspects of the product may be incorporated or formed by appropriate variations to steps of the method, examples of which are shown in Figure 6 and described in detail below.

The invention will now be described, by way of examples only, and with reference to the following Figures in which:

Brief Description of the Drawings Figures 1 A and 1 B show side elevation and plan views respectively of an inner metal cap;

Figures 2A and 2B are corresponding views of the outer cap which revolves around the inner part;

Figure 3A is a part sectional view of the exterior of cap surrounding an inner threaded metal cap;

Figure 3B shows part of Figure 3A in exploded detail;

Figure 4 shows a detailed view of a corner portion of the two-part metal safety cap and how the inner cap is retained within the outer cap;

Figure 5 shows a section through a further embodiment;

Figure 6 is a flow diagram showing key steps of one method of fabricating the two-part metal cap;

Figure 7A shows a plan view of another example of an inner closure cap, which closes a container (not shown) and depicts six raised, embossed dishes arranged around an outer part of the closure cap;

Figure 7B shows a side elevational view of the inner closure cap depicted in Figure 7A;

Figure 8A shows a plan view of another example of an outer closure cap (which surrounds the inner closure cap) and shows six indented, debossed recesses arranged to align with and surround the embossed dishes of the inner closure cap shown in Figures 7A and Figure 7B;

Figure 8B shows a side elevational view of the outer closure cap depicted in Figure 8A;

Figure 9A shows a part sectional, diagrammatic view of an outer closure cap (Figures 8A and 8B) surrounding an inner closure cap (Figures 7A and 7B), and a liner positioned inside the inner closure cap; Figure 9B shows a detailed partial sectional view, of an edge of a rim of Figure 9A, and depicts an embossed dish (of the inner closure cap) aligned with and received in a debossed recess formed in the outer closure cap;

Figure 9C shows a section through the outer closure cap and a side elevational view of the inner closure cap which is received and retained in the outer closure cap;

Figures 10A shows a detailed sectional view through the outer closure cap and shows the pop-up button which spaces the inner and outer caps;

Figures 10B shows a detailed sectional view through the inner and outer closure caps and depicts how the outer cap retains the inner cap by way of a folded curl or hem fold; and

Figure 11 is a partial sectional view showing in detail an indented, debossed recess (on the inner closure cap) surrounding and locating an embossed dish on the outer closure cap.

Detailed Description of Preferred Embodiment of the Invention

Figures 1 A and 1 B show side elevation and plan views respectively of an inner metal cap 10 which has a threaded portion 20 for attaching to a threaded opening of a container, such bottle or jar (not shown). The inner threaded metal cap 10 has a shoulder portion 25 for retaining a liner (not shown).

The metal from which cap 10 is formed may be pressed steel, typically 0.21 mm thick ±20% or aluminium typically 0.28 mm thick ±20% and has a diameter of between 18 and 120 mm and preferably between 30 mm and 100 mm. An outer edge or rim 28 of the inner metal cap 10 may be milled and have grooves or notches, but preferably has a smooth finish. Typically, the height of the rim is between 10 mm and 14 mm.

Referring to Figure 1 B an debossed (embossed) engagement means 30A is shown in relief. Figure 1 B view shows in plan only one example of an engagement means which engages with an engagement means 30B, shown in Figure 2B, and allows torque to be transferred from an outer cap 40 to the inner threaded metal cap 10. This enables removal of the inner cap 10 from the container. A retaining device 50, shown in Figure 3A, retains the inner metal cap 10 within the outer cap 40. Figures 2A and 2B are corresponding views of the outer cap 40 which revolves around the inner part until the embossed (debossed) features align, to enable engagement of the two caps 10 and 40 as described above.

One example of a manufacturing process, for a preferred embodiment of the invention, is summarised in Figure 6.

Figure 3A is a part sectional view of the exterior of cap 40 surrounding inner threaded metal cap 10 which are shown in exploded detail in Figure 3B.

Referring briefly to Figure 3B, when the engagement portions 30A and 30B are in register one with another, the two caps 10 and 40 engage as described above, thereby enabling outer caps and inner threaded metal cap to inter-engage so that the two-part metal safety cap can be removed or screwed on to the container.

In one further alternative embodiment of the two-part metal safety cap, respective engagement means comprise a raised portion on an exterior surface of the inner threaded metal cap and a corresponding indented portion on an inner surface of the outer cap, and an indented portion on an exterior surface of the inner threaded metal cap and a corresponding raised portion on an inner surface of the outer cap, so that the respective portions engage one with another at more than one position when the outer cap is pressed axially towards the inner threaded metal cap.

The height/depth or design of respective indented and/or raised portions on one of the surfaces may be less than the corresponding indented and/or raised portion(s) on an opposing surface so that the degree to which the respective portion(s) engage one with another, when the outer cap is pressed axially towards the inner threaded metal cap, to control or vary the ease of opening and closing of the safety cap. The two emboss/deboss features are dimensioned and sized, so they have sufficient points of contact, when properly aligned one with another, to enable them to fit together when the outer is depressed with enough engagement to allow the unscrewing rotation force to be transferred from the outer cap to the inner cap.

Optionally an indicator showing when engagement portions may be provided to align for engagement is shown as marker or a cut-out portion on the outer cap which aligns with an indicium, such as a key, formed by pressing out (embossing) from the inner threaded metal cap 10, a corresponding shape 30B to engage with the outer cap 40 for fitting to, or removal from, the container (not shown).

The indicator is in the form of one side of any suitable shape or logo such as a padlock or arrows or a brand image and the indicium are in the form of an opposite side of the padlock the shape or logo.

Referring to Figure 6, a method of fabrication of one embodiment of the invention will now be described with reference firstly to the outer cap or outer shell and then with reference to the inner cap or inner shell.

The inner shell or cap is emboss formed from a sheet of metal to engage with outer shell once orientation matched and outer shell depressed.

A thread is then formed around an open end of the inner cap to engage directly with a thread on a jar or bottle opening neck.

An outer shell is emboss formed with a predefined and sized shape dimensioned and arranged to engage with a similar form on an inner shell when both inner and outer caps are orientation matched and when the outer cap or shell is depressed.

The inner cap is inserted within the outer cap.

A curl is then formed to help ensure a safe forming of a cut metal edge. This curl is also sized to retain the inner shell or cap within the outer shell or cap.

The curl when formed also retains the inner cap within the outer cap. This second or retaining stage is performed after insertion of the inner cap into the outer cap in order to retain the inner cap in the outer and so as to provide a sufficient overlap of the curl, and in some embodiments is optionally flattened, to provide sufficient axial space for depressing the outer cap onto the inner cap and to enable respective embossed/debossed regions or portions to inter-engage and so permit unscrewing of the inner cap from a thread of a bottle or jar, as described above.

To manage the degree of engagement between the inner and outer caps, the extent of the embossed or debossed feature(s) on the inner threaded metal cap may be less (shallower) than the extent of the corresponding embossed or debossed engaging feature(s) on the external cap. To manage the degree of engagement between the inner and design and layout of the embossed or debossed engaging feature(s) on the inner cap, it is understood these may be different to the shape and configuration of the corresponding engaging feature on the external cap.

Figure 4 shows a detailed view of a corner portion of the two-part metal safety cap and how the inner cap is retained within the outer cap, for example, using a curl or hem fold.

Variation to the aforementioned embodiments may be made, without departing from the scope of protection as defined by the claims. For example, although inner portion of inner threaded metal cap 10 shown in Figure 4, has a threaded part 20 and an embossed engagement portion 30A and the engagement portion 30A and 30B are in the form of a lock, alternative shaped and dimensioned engagement portions are envisaged.

Continuous thread caps may be formed from in either sheet aluminium or tinplate steel and are typically available in a range of sizes from 18 mm to 120 mm in diameter. Thread forms are specified to fit industry standard container neck sizes and threads.

As both sheet aluminium and tinplate steel are easily identifiable and separable in the waste stream, they may be recycled through smelting, during which process any inserted sealing wad or liner is burnt off. Thus, these two-part metal safety caps provide a sustainable solution to closure requirements.

In another embodiment, depicted in Figures 7Aand 7B, there is shown an inner closure part of a two-part cap. The inner closure has threads which screws on to seal the two- part metal safety cap to the container (jar or bottle) with a thread to match the container.

The inner closure cap has a thread to screw the two-part cap to seal to the jar and the thread and knurled parts supports a suitable liner according to a suppliers requirements and the nature of the contents of the jar.

Figure 7A shows a plan view of another example of an inner closure cap, which closes a container (not shown) and depicts six raised, embossed dishes 200 arranged around an outer part of the closure cap. Figure 7B shows a side elevational view of the inner closure cap depicted in Figure 7A.

Figure 8A shows a plan view of another example of an outer closure cap (which surrounds the inner closure cap) and shows six indented, debossed recesses 210 arranged to align with and surround the embossed dishes 200 of the closure cap shown in Figures 7A and Figure 7B. Figure 8B shows a side elevational view of the inner closure cap depicted in Figure 8A.

Figure 9A shows a part sectional, diagrammatic view of an outer closure cap (Figures 8A and 8B) surrounding an inner closure cap (Figures 7A and 7B) and a liner 220 positioned inside the inner closure cap.

Figure 9B shows a detailed partial sectional view, of an edge of a rim of Figure 9A, and depicts an embossed dish 200 (of the inner closure cap) aligned with, and received in, a debossed recess 210 formed in the outer closure cap.

Figure 9C shows a section through the outer closure cap and a side elevational view of the inner closure cap which is received and retained in the outer closure cap. Figure 10A shows a detailed sectional view through the outer closure cap and shows a spacer 240 which is in the form of a pop-up 230 button that spaces the inner and outer caps.

When the pop-up button 230 is depressed, by a user urging the outer cap towards the inner cap, the respective embossed/debossed (indent) feature(s) on the inner cap engage with corresponding embossed/debossed (indent) feature(s) on the outer cap. This can only occur when the user applies a sufficient force to overcomes the over centring force of the pop-up button 230 to enable it to be depressed and so close the gap between the inner and outer caps. Only then are the respective embossed/debossed (indent) feature(s) on the inner and outer caps able to engage which then enables a twisting force (torque) applied by a user to the outer cap to turn the inner cap enabling it either to be removed or screwed tightly onto a container.

When the user removes an axial force that presses the two caps together, the pop-up button 230 springs back to its relaxed state and spaces the inner and outer caps apart.

Figures 10B shows a detailed sectional view through the inner and outer closure caps and depicts how the outer cap retains the inner cap by way of a folded curl or hem fold. Figure 11 is a partial sectional view showing in detail an indented, debossed recess 210 (on the inner closure cap) surrounding and locating an embossed dish 200 on the outer, closure cap.

It will be appreciated that variation to the aforementioned embodiments may be made, without departing from the scope of protection as defined by the claims.

Claims

1 . A two-part metal safety cap for a container includes an outer cap (outer shell) and an inner cap (inner shell) located therewithin, the inner and outer caps both being formed from sheet metal, the outer cap being in the form of a cylinder shell with an open (distal) end and comprising a (top) surface at a proximal end, a side wall protruding therefrom and a curled edge is formed around a rim of the side wall to define a curl, which lies within the open end of the outer cap, and retains the inner cap within the outer cap and wherein the top surface of the outer cap has at least one embossed/debossed (indent) feature; the inner cap being in the form of a smaller diameter cylinder shell, open at its distal end and having a (top) surface at a proximal end and a side wall protruding therefrom, the inner walls of the inner cap including a threaded portion which extend around at least a portion of a rim of the side wall to an opening of the inner cap, the top surface of the inner cap includes at least one embossed/debossed (indent) feature and each of the surfaces is adapted such that when the outer cap is located in the correct orientation with respect to the inner cap, depression of the outer cap causes the embossed/debossed (indent) feature(s) of the outer cap to engage positively with the embossed/debossed (indent) feature(s) of the inner cap, characterised in that a pop-up button is provided on at least one surface of the outer cap or the inner cap, which in a relaxed state spaces the inner cap from the outer cap and when a user applied force overcomes an over centring force of the pop-up button to depress it, this enables corresponding embossed/debossed (indent) feature(s) on the inner cap to engage with the embossed/debossed (indent) feature(s) on the outer cap and thereby enables coupling of a torque applied to the outer cap to turn the inner cap.

2. A two-part metal safety cap as claimed in claim 1 wherein the pop-up button is dimensioned and arranged such that in an undepressed state, rotation of the outer cap, does not result in rotation of the inner cap.

3. A two-part metal safety cap as claimed in either claim 1 or 2 wherein the inner cap is press fitted into the outer cap.

4. A two-part metal safety cap as claimed in any preceding claim the inner and/or outer cap portions are formed form aluminium gauge 0.28 mm ± 20% or tinplate gauge 0.21 mm ± 20%.

5. A two-part metal safety cap as claimed in any preceding claim wherein a rim of an open end of the outer cap portion is provided with an inwards deformation or curl.

6. A two-part metal safety cap as claimed in any preceding claim including a wad is located between an inner surface of the outer cap and an outer surface of the inner cap portion.

7. A two-part metal safety cap as claimed in any preceding claim wherein at least the inner cap has a protective coating applied thereto.

8. A two-part metal safety cap according to any preceding claim wherein the inner threaded cap includes a liner.

9. A two-part metal cap according to any preceding claim wherein a retaining means includes a curl and/or at least one clip disposed around a rim of the outer cap and/or at least one bead disposed around a rim of the outer cap.

10. A two-part metal safety cap according to any preceding claim wherein an indicator is provided on the outer cap and the inner threaded cap, which when aligned indicates the caps are positioned for inter-engagement.

11 . A two-part metal safety cap according to claim 10 wherein the indicator is a lock shape cut-out in the exterior metal cap and an image of a key provided on an exterior surface of the inner threaded cap and whereby when the key is visible through the lock shape cut-out, inter-engagement of the inner and exterior metal caps is permitted.

12. A two-part metal safety cap according to any preceding claim wherein a plurality of embossed/debossed (indent) feature(s) are provided around a first circular path, on the outer cap, and on a second circular path on the inner cap, the diameter of the second circular two paths being the same.

13. A two-part metal safety cap according to claim 12 wherein six embossed/debossed (indent) feature(s) are provided around each of the first and second circular paths.

14. A method of producing a two-part metal safety cap for a container, the two-part metal safety cap including an outer cap portion and an inner cap portion, comprising the steps of: a) forming an outer cap (or shell) from sheet metal by one or more pressing/stamping steps, the outer cap (or shell) including a top surface, b) forming an embossed/debossed (indent feature) in the top surface of the outer cap (shell), c) forming an inner cap (or shell) portion from sheet metal by one or more pressing/stamping steps, the inner cap (shell) including a top surface, d) forming an embossed/debossed (indent feature) in the top surface of the inner cap portion, e) forming a pop-up button on at least one surface of the outer cap or the inner cap, which in a relaxed state spaces the inner cap from the outer cap; f) press fitting the inner cap into the outer cap portion; and g) forming a curl around a lower edge of the outer cap by folding, rolling or pressing the lower edge whereby the inner cap is retained by its rim engaging with the curl of the lower edge of the outer cap.

15. A method as claimed in claim 14 wherein the steps b) and/or d) include a pressing/stamping operation.

16. A method as claimed in either claim 14 or 15 including the step of forming a thread on the inner surface of the inner cap.

17. A method as claimed in any of claims 14 to 16 wherein step e) comprises press fitting such that the top surface of the inner cap portion lies adjacent an inner surface of the top surface of the outer cap portion and whereby corresponding embossed/debossed (indent) features are not positively engaged one with each other.

18. A method as claimed in any of claims 14 to 17 wherein the inner and or outer cap portions are formed form aluminium gauge 0.28 mm ± 20% or tinplate gauge 0.21 mm ± 20%.

19. A method as claimed in any of claims 14 to 18 wherein the rim of the open end of the outer cap portion is provided with an inwards deformation or curl.

20. A method as claimed in any of claims 14 to 19 wherein a protective coating is applied to at least one surface of the inner cap or outer cap.

21 . A method as claimed in any of claims 14 to 20 includes applying a film of oil to at least one surface of the inner cap or outer cap during a forming step.

22. A two-part metal cap according to any of claims 1 to 13 wherein the outer cap and the inner threaded cap are formed from aluminium.

23. A two-part metal cap according to any of claims 1 to 13 wherein the outer cap and the inner threaded cap are formed from a ferro-magnetic material, such as steel.

24. A two-part metal cap according to either claim 22 or 23 wherein the inner cap is between 18 mm and 120 mm in diameter.