Plasma treatment method for coating a glass syringe body for a hypodermic pre-filled glass syringe

1. A method for forming a coating on an inner surface of a glass syringe body comprising the steps of:

applying at least one emulsion and/or one solution containing at least one layer-forming substance to at least one inner surface of the glass syringe body, said glass syringe body having an axial direction (A) and comprising a syringe cone positioned at a first end of the glass syringe body along the axial direction (A);

generating plasma using an atmospheric-pressure plasma source positioned in front of the first end of the glass syringe body;

subsequently exposing at least a partial surface of an inner surface of the syringe cone to the plasma, wherein the plasma is introduced into the glass syringe body from the atmospheric-pressure plasma source through the syringe cone;

simultaneous with exposing at least the partial surface of the inner surface of the syringe cone to the plasma, applying a negative pressure of less than atmospheric pressure to a second end of the glass syringe body, wherein the negative pressure is provided by a negative pressure source arranged at the second end of the glass syringe body, and wherein the second end of the glass syringe body is opposite to the first end of the glass syringe body in the axial direction (A).

2. The method according to claim 1 , wherein a suction mandrel of the negative pressure source is introduced into a plunger chamber of the glass syringe body.

3. The method according to claim 2 , wherein the suction mandrel is brought into a sealing contact with an inner side and/or a bottom surface of the plunger chamber.

4. Then method according to claim 1 , wherein the coating comprises a carbon content which decreases to less than about 80% of the initial value before the plasma treatment.

5. The method according to claim 1 , wherein the layer thickness of the coating in at least the partial surface of the inner surface before the action of the plasma is between about 20 nm and about 100 nm and decreases in the partial surface by more than about 20% as a result of the plasma treatment.

6. The method according to claim 1 , wherein a layer thickness of more than about 70% remains after the plasma treatment in the partial surface.

7. The method according to claim 1 , wherein the emulsion and/or the solution comprises at least one silicone oil and optionally water, and/or the coating contains at least carbon and oxygen and hydrogen and silicon, and/or the coating contains at least one poly(-organo)-siloxane.

8. The method according to claim 1 , wherein the partial surface of the inner surface of the syringe cone is hydrophobic before the plasma treatment and hydrophilic after the plasma treatment.

9. The method according to claim 1 , wherein the plasma comprises an active gas, wherein the active gas optionally comprises oxygen or synthetic air or atmospheric air.

10. The method according to claim 1 , wherein the plasma acts for about 0.4 to about 5 seconds, and/or an atmospheric-pressure plasma generated with a dielectrically impeded discharge is used, and/or the plasma comprises an inert gas, and/or that the plasma is formed as a plasma beam or plasma jet which acts at least on the partial surface of the inner surface of the syringe cone, and/or the plasma acts while the negative pressure is provided.

11. The method according to claim 1 , further comprising connecting an injection needle to the glass syringe body along a joint by means of an adhesive, wherein the joint comprises the partial surface of the inner surface of the syringe cone.

12. The method according to claim 11 , wherein the adhesive is selected from an acrylate and/or a polyurethane and/or an epoxy resin and/or a cyanoacrylate.