In sealing packages in the form of test tubes con- taining medicinal preparations it is important to prevent sterilised preparations that are contained in the pack- ages from being contaminated during the very package- sealing process. In this connection rubber stoppers are used in order to stop such test tubes. The stoppers are initially subjected to washing and rinsing treatments, followed by sterilisation and drying. Prior to the sterilisation step the stoppers are also treated with silicon to ensure that they do not adhere to one another when stored after the sterilisation step, but also to make the stoppers sufficiently pliable for convenient application to the test tubes one by one and for effi- cient sealing of the tubes.

In accordance with a previously known method washed stoppers are deposited on a vibrating table, known as a shaker. A mist of silicon is sprayed onto the stoppers which are subsequently collected in containers or bags in which they are sterilised in an autoclave.

In accordance with another prior-art method a thin silicone oil is mixed with water and an emulsifying agent is added to promote mixing. Thus, an emulsion is formed which is pumped into a container holding stoppers there- in. The stoppers are siliconised, sterilised, and dried inside the container.

The latter method is advantageous compared with the first-mentioned method inasmuch as it is more convenient to put into practice. From an environmental aspect this latter method is, however, disadvantageous in that it requires the addition of a chemical substance for the emulsion to be produced.

The object of the present invention is to provide a method of forming an emulsion from silicon and water without having to resort to the addition of any chemical substances, which emulsion may be used to efficiently siliconise rubber stoppers. This object is achieved by means of the inventive method according to which silicone oil and water alone are mixed while being stirred with sufficient vigour to produce an emulsion, and the result- ing emulsion is directed to a container in which the stoppers are stored and the siliconising process is carried out.

The invention likewise concerns a device for per- forming the method. The features characterising the device are defined in the appended claims 3 and 4.

The invention will be described in more detail in the following with reference to the accompanying drawing which is a schematic representation of the inventive device.

A dosage pump 4 is installed in a conduit 1 leading from a vessel 2 holding silicone oil 3. Downstream from the dosage pump 4 a shut-off valve 5 is mounted in the conduit 1. The conduit 1 branches into a water-supply conduit 6 in which is likewise mounted a shut-off valve 7. Water supplied via the conduit 6 is mixed with dosed amounts of silicone oil 3 that are discharged from the pump 4 and transported through the conduit 1. Downstream from the junction 8, where conduit 1 branches into con- duit 6, a dispersing pump 9 is provided, and in a conduit 10 leading from pump 9 to a container 11 for storage of rubber stoppers to be siliconised are mounted a further shut-off valve 12 and a throttle valve 13.

The method in accordance with the invention is carried out in the following manner. Water and silicone oil 3 in the desired proportions are pumped into the pump 9. The dispersion carried out therein is sufficiently vigorous to produce an emulsion independently of whether the silicone oil is a high-viscosity or a low-viscosity

oil. The emulsion is then pumped into the container 11 wherein a mixture 14 of emulsion and rubber stoppers is formed. Siliconising of the rubber stoppers thereafter takes place, as a result of which the stoppers receive a thin silicon coating.

In accordance with a further development of the method according to the invention, air is blown into the mixture 14 of emulsion and stoppers, resulting in the emulsion (the silicon) adhering so well to the surface of the stoppers that the residue liquid essentially will consist exclusively of water. This water is drained off.

In an already known manner, vapour is supplied to the container to sterilise the stoppers which are subsequent- ly dried. The container may then serve as a stopper storage means where the stoppers may be kept until they are to be used.

The throttle valve 13 is provided to allow variable throttling of the flow to the container 11. In this man- ner it becomes possible to regulate the emulsion mixing time inside the dispersing pump 9 in order to obtain optimum dispersing results.