Syringe and gasket systems
A process for producing gaskets with an improved channel for use in matched syringe and plunger systems, preferably prefilled plastic syringe systems. In particular, an improved process for making and inspecting continuous channels in a gasket film by laser treatment. The gaskets are useful in matched syringe and plunger systems with high and consistent container closure integrity (CCI), and consistent break loose and glide forces over time, and sealability.
1. A process for making one or more continuous channels in a film residing on at least a circumferential outer surface portion of a gasket, the gasket comprising a main body made of an elastic material, the main body having a circumferential surface portion and an internal cavity in its center, the cavity being defined by an inner surface portion of the gasket and being open at one end, the process comprising the following steps:
(a) inserting a portion of one end of a mandrel into the open end of the cavity;
(b) securing the gasket to the mandrel;
(c) positioning the mandrel and secured gasket in proximity to a laser; and
(d) applying a laser beam emitted from the laser to one or more selected locations on a surface portion of the film residing on the circumferential outer surface portion of the gasket while rotating the mandrel and the secured gasket along the mandrel's longitudinal axis to produce one or more continuous channels in the film, the channels extending around the entire circumference of a circumferential outer surface of the gasket.
2. The process of claim 1 , wherein the thickness of the film on the surface of the gasket prior to step (d) is about 10-30 microns, about 15-35 microns, about 20-50 microns, or about 20 microns.
3. The process of claim 1 , wherein the film has one or more of good slidability and chemical stability.
4. The process of claim 1 , wherein the film is capable of preventing migration of components from the elastic material of the gasket.
5. The process of claim 1 , wherein the gasket is secured to the mandrel by press-fit assembly.
6. The process of claim 1 , wherein the diameter of at least a part of the mandrel portion that is inserted into the internal cavity of the gasket is greater than the inner diameter of the cavity.
7. The process of claim 1 , wherein when more than one channel is produced, the channels are axially spaced.
8. The process of claim 1 , wherein the one or more channels have axially opposed first and second side walls and a floor.
9. The process of claim 8 , wherein the one or more channels each independently has one or more of:
(a) an axial width between the side walls selected from 1-100 microns, 5-50 microns, 10-30 microns, and 15-25 microns;
(b) a radial depth selected from 0-100 microns, 5-50 microns, 10-30 microns, and 15-25 microns; and
(c) a laser-cut depth selected from 20-80 microns, 30-60 microns, 40-50 microns, 50-60 microns, 40-45 microns, 45-50 microns, 50-55 microns and 55-60 microns.
10. The process of claim 1 , wherein the one or more channels extend through the film into the outer surface portion of the gasket.
11. The process of claim 1 , wherein the one or more channels comprise a first circumferentially extending lip located adjacent to the first side wall of the channel and extending radially above the film and, optionally, a second
circumferentially extending lip located adjacent to the second side wall and extending radially above the film.
12. The process of claim 11 , wherein the first and second lips independently have a peak height selected from 10-100 microns, 15-60 microns, 20-50 microns, or 30-40 microns and a peak width selected from 200-1,000 micron, 275-550 microns, 300-400 microns, or 450-500 microns.
13. The process of claim 11 , wherein each lip comprises film material displaced from the channel by the laser beam as the channel is produced.
14. The process of claim 13 , wherein at least one lip is capable of being positioned in a tubular syringe barrel so as to form a seal against the inner surface of the barrel.
15. The process of claim 1 , wherein the position of the laser relative to the mandrel and secured gasket is controlled by a servo-motor.
16. The process of claim 1 , wherein the film is a fluoropolymer film.
17. The process of claim 15 , wherein the fluoropolymer film is polytetrafluoroethylene (PTFE).
18. The process of claim 1 , wherein the gasket is characterized by one or more of a dimensional tolerance selected from ±100 micron, ±50 microns, ±35 microns, ±25 microns, ±20 microns, ±15 microns, ±10 microns, ±5 microns, or ±3 microns; and fewer than 300 particles of 2 micron size or more, measured using light obscuration (LO) or microflow imaging (MFI).