Capsule for the Storage and Vibration-Mixing of Two Components Particularly for Dental Purposes

This invention relates to a capsule for the storage and vibration-mixing of two components and is particularly useful for dental purposes.

A multicomponent capsule for dental purposes is already known, wherein a substantially cylindrical section contains a mixing chamber having planar end walls one of which is provided with a small hole, and a hollow cover is attached telescopically at this end and encloses a foil bag. The mixing chamber contains one component, while the foil bag contains the other, liquid component. Before mixing, the cover is pressed against the planar end wall so that the foil bag bursts and pours its contents into the mixing chamber through the small hole. Then the capsule is inserted into a vibration mixer, which moves the capsule backwards and forwards, generally in its longitudinal direction, and thus produces homogenisation of the two components. A disadvantage of this known type of multicomponent capsule is that special manipulation is necessary before mixing, in order to transfer the liquid component to the mixing chamber, and this is often not possible without the use of considerable force.

The present invention is concerned with providing a capsule in which no special manipulation for the transfer of liquid to the mixing chamber is required before the mixing process.

According to the present invention there is provided a capsule for the storage and vibration-mixing of two components comprising a mixing chamber in which one of said components is stored, said chamber having an aperture which is closed by means of a removable closure member and a foil bag which can be reptured without disintegration by the mixing movement housed in said mixing chamber and containing the other of said components in liquid form.

During the vibration mixing, extraordinarily high acceleration forces are exerted on the contents of the capsule. The foil bag can be easily designed in such a manner that it does not adapt to this acceleration, but ruptures or bursts and releases its contents. The smallest of openings in the bag resulting from the rupture is sufficient to empty the liquid contents into the mixing chamber, under the effect of the forces prevailing. There is no difficulty in ensuring that the foil bag opens reliably, by appropriate selection of foil thickness, foil material, arrangement of predetermined breaking strengths, breakable welds and the like. This is particularly simple, if the enclosed liquid is of high specific gravity, such as mercury, since then particularly high forces act on the foil bag during vibration mixing. Disintegration or splintering of the foil bag does not occur, if an appropriate choice is made from the polymeric or elastomeric materials normally used for such a purpose. In many cases, metal foils may also be suitable.

It is already known for one component to be placed in a breakable glass bubble inside the mixing chamber of multicomponent mixer containers. There is, however, the danger that when using a vibration mixer a brittle material such as glass may disintegrate and form many small splinters which could be distributed throughout the mix and make it unsuitable for use. It is a surprising effect, on the contrary, that a soft material such as those normally used for the manufacture of foil bags, does not disintegrate but substantially retains its original size, and can therefore easily be removed from the mix. Because of the different structures and specific gravities of the mix, on the one hand, and the foil bag residue on the other, these are usually separated during the mixing motion, so that it is not necessary to exert any special care when removing the mix, for separation of the foil bag residue.

A further disadvantage of the aforementioned known multicomponent capsules for dental purposes is that even with the best of sealing between that section of the capsule which forms the mixing chamber, and the cover, a certain proportion of the liquid component can escape into the atmosphere during vibration mixing. This is particularly hazardous when mercury is being used as the liquid component. A preferred embodiment of the present invention provides a multicomponent capsule which does not have this disadvantage. For this purpose, the mixing capsule of the embodiment is designed so that the cover or closure member is connected to the section of the capsule which forms the mixing chamber, by means of a seal having a predetermined breaking strength. The closure member and the section of the capsule forming the mixing chamber may be formed as a single unit, or they may be welded or bonded together, in which case the predetermined breaking strength is most conveniently formed in the region of this weld or adhesion. In this way it is possible to guarantee absolute tightness during the vibration mixing. The closure member is easily broken from the section of the capsule which forms the mixing chamber, for opening the capsule and for removing the mix.

Of course, in this respect it is not significant how large the closure member is in relation to the section of the capsule which forms the mixing chamber. The predetermined breaking strength need not be arranged in a seal at one end of the section of the capsule which forms the mixing chamber. It can be provided in any central region of this section of the capsule, and then that part of the capsule which is referred to as the cover, is formed by one half of the capsule section which forms the mixing chamber.

In order to facilitate breakage of the closure member from the remainder of the capsule a lever can be provided, which can be locked onto the closure member as a result of its shape. This lever can be formed in the most simple way, by a cylindrical rod which can be inserted into a corresponding cylindrical socket in the closure member. Of course, the closure member can be fitted initially with an appropriate extension. It is very convenient if the end of the lever is shaped as a spatula.

An embodiment of the present invention will now be described by way of example with reference to the drawing, which shows the capsule in longitudinal section, at about its normal size.

The capsule has a cylindrical section 1, which forms the mixing chamber 2, and is closed at one end by a curved wall. At the other end, the capsule section 1, has an aperture which is closed by a closure member 3. At 4, the section of the capsule which forms the mixing chamber and the closure member, are glued or welded together to form a seal, and this seal is chosen so that sufficient tightness of seal is ensured but the mechanical strength is limited. The closure member 3 has an external extension 5 which is in the form of a cylindrical socket, the bore of which fits the end 6, of a small rod 7. If this is inserted into the extension of the closure member 3, then a bending moment can be exerted about the seal 4, in the direction of the pair of arrows, so that the closure member can be released from the other part of the capsule. The small rod 7, at its end 8, is drawn out to give a wedge-shaped side view (shown as dotted lines), so that it can be used as a spatula for removal of the mix from the chamber 2.

In the mixing chamber 2, are a powder component 9, and a foil bag 10, which may be formed, for example, from two circular foil discs, welded together at the edges to enclose the liquid. For inclusion of mercury this may consist, for example, of two foil discs welded together, each 0.05 mm thick, of polyethylene, polypropylene, polyamid or similar polymeric materials.