Coating processes – Medical or dental purpose product; parts; subcombinations;... – Device for creating or holding open an unnatural opening in...
Reexamination Certificate
1998-12-04
2001-10-02
Beck, Shrive P. (Department: 1762)
Coating processes
Medical or dental purpose product; parts; subcombinations;...
Device for creating or holding open an unnatural opening in...
C427S230000, C427S236000, C427S489000, C427S515000, C427S256000
Reexamination Certificate
active
06296893
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a pharmaceutical packing or filling device, which comprises an extended or elongated hollow plastic body having an axial length and a cylindrical portion extending over at least part of the axial length, which is provided with an interior silicone lubricant layer in this cylindrical portion and which is tightly closed by a stopper. It also relates to a method of making this pharmaceutical packing or filling device.
2. Prior Art
In the pharmaceutical packing device comprising the extended hollow plastic body an elastomeric closing member, e.g. a piston or a piston stopper, is inserted in its hollow interior space, and is slidable in the extended hollow plastic body, bearing flexibly on its interior wall. Typical examples include plastic syringe cylinders for pre-filled syringes, injector devices for cylindrical ampoules and capsules, and also piston burettes in analytical chemistry applications.
In order to overcome various problems typically a silicone lubricant layer is provided on the interior wall of the hollow plastic body.
According to U.S. Pat. No. 4,767,414 and European Patent EP 0 201 915 B1 silicone oil is applied to the surface of the interior wall. In the method described in these references the surface is activated with ionizing plasma to obtain good adherence and the silicone oil applied to it is similarly treated with ionizing plasma.
This process is comparatively inconvenient. Also the silicone oil is comparatively non-reactive, i.e. free silicone oil, which is exposed to the contents of the hollow plastic body in operation of the piston. The introduction of the silicone oil in the human body in the case of injectors should be reduced to a minimum for known reasons. U.S. Pat. No. 4,844,986 describes a process for providing a silicone lubricant layer to the interior wall of the hollow plastic body by means of plasma polymerization for preparation of a coating of polydimethylsiloxane.
Also this process requires activation of the plastic surface and a multistep application process.
European Patent Document EP 0 329 041 describes a process for coating the interior wall of a hollow plastic body with a polysiloxane, or polysilane or polysilazane by means of an ionizing plasma, whereby an adherent layer of this material is first produced and then a thin lubricant layer is applied over it.
Also this process requires activation of the plastic surface and comprises many steps.
The same is true of the process described in EP 0 302 625 B1, according to which the surface of the interior wall of the hollow plastic body is first treated with plasma in order to obtain a plasma treated polymer surface. Then a layer of a polysiloxane lubricant is applied to that surface without plasma treatment. The polysiloxane lubricant is provided with a suitable predetermined surface tension so that it will wet the plasma treated surface completely.
Finally U.S. Pat. No. 5,338,312 describes a coating for the interior wall of a hollow plastic body, on which two lubricant layers are applied over each other, namely a base layer of silicone oil with a higher viscosity applied on the interior wall by means of an adhesive layer and a surface layer of silicone oil with a lower viscosity. The silicone oils of the individual layers are preferably cross-linked by means of ionized plasma.
Similarly expensive process engineering is required to provide the lubricant layers in this last process. Among other things, the surface layer contains much free, i.e. non-reactive, silicone oil.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a pharmaceutical packing device of the above-described type comprising an extended or elongated hollow plastic body having a cylindrical portion extending over at least part of its axial length, which is provided with a silicone lubricant layer in this cylindrical portion and which is tightly closed by a stopper, which is structured so that it can be made in a simple manner by a single stage process and so that the contamination of the contents of hollow plastic body with silicone droplets is minimized.
It is also an object of the invention to provide a method of making the pharmaceutical packing device of the above-described type that is simple, that consists of a single stage process without contamination of the contents of the container with silicone droplets.
According to the invention the lubricant layer is made from a mixture of reactive silicone oil with non-reactive silicone oil.
The process for making the pharmaceutical packing device comprising the hollow plastic body that attains the above-described objects comprises the following steps:
a) forming the hollow plastic body with known engineering methods;
b) preparing a mixture of reactive silicone oil with non-reactive silicone oil;
c) applying the mixture of the silicone oils to the interior wall of the hollow plastic body on the cylindrical portion of the hollow plastic body to form a preliminary or precursor layer with known methods;
d) cross-linking the mixed silicone oils in the preliminary layer to form the lubricant layer; and
e) processing the hollow plastic body provided with the lubricant layer according to its predetermined application. The principle feature of the invention thus is the use of a mixture of reactive silicone oil and non-reactive silicone oil. It is especially surprising that use of this type of mixture does not require activation of the surface of the hollow plastic body.
According to a preferred embodiment of the invention this occurs when the plastic material, from which the hollow plastic body is made, is a cycloolefin polymer or a copolymer (COC) and the mixture of silicone oils is applied immediately after the molding or forming of the hollow plastic body to its interior wall, while the hollow plastic body is still heated, preferably at a temperature over 40° C.
The invention permits the application of the silicone lubricant layer to the hollow plastic body in a single step process, which means without expensive activation of the surface or multistep application processes. The reactive silicone oil component forms an adherent base layer after the cross-linking, in which the partially non-reactive silicone oil component is locally embedded which provides the lubrication properties.
Reactive silicone oils contain reactive functional groups, which permit cross-linking to themselves and as needed with other surfaces, in contrast to non-reactive silicone oils.
Thus a separating and lubricating layer is formed between the container (hollow plastic body) and moving elastomeric component (stopper).
The structure of the layer is based on a siloxane molecule that contains functional groups according to its hardening mechanism according to its function.
Reactive silicone oil especially contain vinyl groups, which cross-link under the influence of heat (temperature) and ultraviolet radiation (UV). Particularly the cross-linking reaction is catalyzed by platinum compounds.
The hardened silicone oil then forms a solid film, which functions as a separating layer between the hollow plastic body and the piston-like stopper. Because of that a baking of the stopper, especially when it is made of bromobutyl, onto the COC surface of the hollow plastic body is prevented. Dimethylpolysiloxane may be admixed to the reactive silicone oil as a non-reactive silicone oil for reduction of the sliding friction.
A siliconizing agent based on a reactive silicone oil is preferably formed from vinyl-group-containing silicone oil, cross-linking agent, catalyst, solvent and non-reactive dimethylpolysiloxane having a viscosity of from 350 to 20000 cSt.
The use of a mixture of reactive and non-reactive silicone oil as lubricant is already known from U.S. Pat. Nos. 4,806,430 and 4,720,521. In the known case however only metal substrates, such as injector needles, razor blades or the like, were coated. The present invention in contrast comprises an improved pharmaceutical packing device provided with the above-described
Heinz Jochen
Spallek Michael
Weber Gerhard
Beck Shrive P.
Kolb Jennifer
Schott Glass
Striker Michael J.
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