Sterilizing container

Details Sterilizing container Sterilizing container

1999-11-04

2001-06-19

Castellano, Stephen (Department: 3727)

Receptacles

Closures

Vent in closure

C220S912000

Reexamination Certificate

active

06247609

ABSTRACT:

The invention relates to a sterilizing container with a broken through area which is covered by a flat filter layer.
Sterilizing containers usually have a broken through area through which hot steam can pass into the interior and air can flow out of the interior into the environment so that bacteria and other germs inside the sterilizing container are destroyed by the steam entering at a high temperature. Known filter layers are, for example, in the form of paper filters which have to be exchanged after each sterilizing operation.
Long lasting filters with a longer service life are also known, for example, ceramic filters or filters consisting of porous wall materials of the sterilizing container. Such long lasting filters require special container structures, and, in addition, these are very complicated constructions.
The object of the invention is to so convert a generic sterilizing container without any constructional alterations thereto that filters which last for a large number of sterilizing operations are usable.
This object is accomplished in a sterilizing container of the kind described at the outset, in accordance with the invention, in that the filter layer consists of polytetrafluoroethylene (PTFE) and is built up of compact PTFE particles which fuse together and form pores between them. Instead of conventional disposable filters, for example, paper filters, a specially designed filter layer consisting of polytetrafluoroethylene is used. This material is usually compact and, therefore, not suitable for filtering purposes. The specially provided filter layer becomes porous and is, therefore, suitable as filter material by being built up of individual compact PTFE particles which have fused together to form pores. The fusing preferably takes place at a temperature which lies just above the microcrystalline melting temperature, for example, at a temperature just above 360° C., and the particles are fused together under pressure at this temperature, which is thus a sintering process.
A PTFE filter layer produced in this way has the necessary porosity to enable entry and exit of air and steam in a sterilizing container, but, on the other hand, to retain germs in a reliable manner. The PTFE material is chemically inert and does not undergo any changes even under the relatively aggressive conditions of the sterilizing operation, and, therefore, a large number of sterilizing operations can be carried out with such a long lasting filter, for example, of the order of 300, before exchange of the filter layer becomes necessary. The filter layer can even remain in the sterilizing container for the aggressive washing operations and the sterilizing operations at high temperature. Owing to the chemical properties of polytetrafluoroethylene, the filter layer does not suffer any damage even during these aggressive treatments.
The size of the particles building up the filter layer preferably lies at between 50 and 500 &mgr;m, in particular, between 100 and 300 &mgr;m.
The filter layer may have a thickness of between 0.3 and 1 mm, preferably between 0.5 and 0.8 mm.
It is particularly advantageous for the filter layer to be a peel-off film which is produced by being peeled off mechanically from a porous PTFE block. When this filter layer is peeled off the PTFE block, completely clean surfaces are produced and, therefore, in contrast to films that are produced in a different way, for example, no release agents at all are to be found on the surface. This firstly has the advantage that the filter layer consists exclusively of PTFE, and, it is, therefore, ensured that no foreign matter gets into the sterilizing container, but, secondly, it has surprisingly emerged that this complete freedom of the surface from foreign matter makes it possible to mark such a surface with special colors, for example, with colors in particle form which are mixable with water, as are used in colored pens for smooth surfaces, namely so-called board markers. The conventionally produced PTFE surfaces do not take on these colors. The completely clean peeled off surface does, however, accept these colors, particularly when these colors are present in particle form in a solution and can, therefore, become embedded in the pores of the filter layer. This makes it possible to write on the filter layer, for example, in order to indicate an expiration or exchange date. It is, therefore, also advantageous for the filter layer to have writing areas in which the user can enter the desired data with such a pen. These writing areas preferably lie under an opening in the sterilizing container structure so that the inserted filter layer can be written upon through such an opening or such a window.


REFERENCES:
patent: 4704254 (1987-11-01), Nichols
patent: 5372787 (1994-12-01), Ritter
patent: 5968459 (1999-10-01), Nalepa et al.
patent: 6077485 (2000-06-01), Baker
patent: 0 247 771 (1987-12-01), None
Brochure, “Polysteribox” of Ritter Med.
Brochure, “Sterion Sterilization Container System,” Johnson & Johnson Medical Inc., Sep. 1996.
Brochure, “Mini Container,” C.B.M. s.r.1., Officine metalmeccaniche.

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