Pharmaceutical syringe piston

Patent metadata

Field	Value
Publication number	US-11951289-B2
Application number	US-202217828046-A
Country	US
Kind code	B2
Filing date	May 31, 2022
Priority date	Apr 5, 2013
Publication date	Apr 9, 2024
Grant date	Apr 9, 2024

Abstract

A piston having a longitudinal axis and opposing proximal and distal axial ends is manufactured by a method including molding a partially formed piston body and then molding the piston. The partially formed piston body is molded by placing a first rubber sheet and an inert film between die plates of a first forming tool, vulcanizing the first rubber sheet and the inert film between the die plates of the first forming tool, and blanking out the partially formed piston body from the first rubber sheet and the inert film. The piston is then molded by placing the partially formed piston body into a second forming tool, placing a second rubber sheet into the second forming tool, vulcanizing the second rubber sheet and the partially formed piston body together, and blanking out the piston from the second rubber sheet at a trim edge spaced apart from the inert film.

First claim

What is claimed is:

1. A piston manufactured by a method comprising:
placing a first rubber sheet and an inert film between die plates of a first forming tool;
vulcanizing the first rubber sheet and the inert film between the die plates of the first forming tool to form a first piston body, the first piston body comprising a central face portion at a distal axial end of the first piston body and an annular curved portion, the central face portion and at least a part of the annular curved portion being enclosed by the inert film;
blanking out the first piston body from the first rubber sheet and the inert film;
placing the first piston body into a second forming tool;
placing a second rubber sheet into the second forming tool;
vulcanizing the second rubber sheet and the first piston body together to form a second piston body, the second piston body comprising a proximal axial end that circumscribes the second piston body and a rib;
joining the second piston body to the first piston body to form the piston; and
blanking out the piston from the second rubber sheet at a trim edge, wherein:
the trim edge is spaced apart from the inert film between the inert film and the proximal axial end, and
an outer diameter of the trim edge is less than a maximum outer diameter of the rib.

2. The piston of claim 1 , wherein the piston comprises a sealing portion proximately connected to the annular curved portion, the sealing portion having an outer circumference.

3. The piston of claim 2 , wherein the inert film does not extend along the sealing portion.

4. The piston of claim 2 , wherein the rib is between the sealing portion and the proximal axial end.

5. The piston of claim 4 , wherein:
the sealing portion has a maximum outer diameter, and
the maximum outer diameter of the sealing portion is greater than the maximum outer diameter of the rib.

6. The piston of claim 4 , wherein the trim edge is proximally spaced apart from the rib.

7. The piston of claim 2 , wherein the trim edge is proximally spaced apart from the sealing portion.

8. The piston of claim 1 , further comprising a recess adjacent to the rib, wherein:
the recess comprises an outer diameter that is less than the outer diameter of the trim edge.

9. A syringe comprising a barrel and a piston within the barrel, the piston manufactured by a method comprising:
placing a first rubber sheet and an inert film between die plates of a first forming tool;
vulcanizing the first rubber sheet and the inert film between the die plates of the first forming tool to form a first piston body, the first piston body comprising a cylindrical portion, a central face portion at a distal axial end of the first piston body, and an annular curved portion, the central face portion and at least a part of the annular curved portion being enclosed by the inert film;
blanking out the first piston body from the first rubber sheet and the inert film;
placing the first piston body into a second forming tool;
placing a second rubber sheet into the second forming tool;
vulcanizing the second rubber sheet and the first piston body together to form a second piston body and joining the second piston body to the first piston body to form the piston, the second piston body comprising a proximal axial end that circumscribes the second piston body; and
blanking out the piston from the second rubber sheet at a trim edge, wherein:
the trim edge is spaced apart from the inert film between the inert film and the proximal axial end,
the cylindrical portion and the part of the annular curved portion maintain a fluid-tight seal with an inner wall of the barrel, and
an outer boundary of the inert film is configured to be proximate to a leading-distal edge of the fluid-tight seal to minimize contact between the inert film and the inner wall of the barrel.

10. The syringe of claim 9 , wherein the annular curved portion extends between a first axial end of the cylindrical portion and the central face portion.

11. The syringe of claim 10 , wherein the fluid-tight seal comprises a trailing-proximal edge at a second axial end of the cylindrical portion, and the fluid-tight seal is continuous between the leading-distal edge and the trailing-proximal edge.

12. The syringe of claim 11 , wherein the outer boundary of the inert film is closer to the leading-distal edge of the fluid-tight seal than to the trailing-proximal edge of the fluid-tight seal.

13. The syringe of claim 9 , wherein the outer boundary of the inert film is adjacent to the leading-distal edge of the fluid-tight seal.

14. A syringe comprising a barrel and a piston within the barrel, the piston manufactured by a method comprising:
placing a first rubber sheet and an inert film between die plates of a first forming tool;
vulcanizing the first rubber sheet and the inert film between the die plates of the first forming tool to form a first piston body, the first piston body comprising a central face portion at a distal axial end of the first piston body, and an annular curved portion, the central face portion and at least a part of the annular curved portion being enclosed by the inert film;
blanking out the first piston body from the first rubber sheet and the inert film;
placing the first piston body into a second forming tool;
placing a second rubber sheet into the second forming tool;
vulcanizing the second rubber sheet and the first piston body together to form a second piston body and joining the second piston body to the first piston body to form the piston, the second piston body comprising a proximal axial end that circumscribes the second piston body; and
blanking out the piston from the second rubber sheet at a trim edge, wherein:
the trim edge is spaced apart from the inert film between the inert film and the proximal axial end,
the central face portion is oriented coaxially with respect to a longitudinal axis of the piston, the piston defining a first piston diameter measured perpendicularly to the longitudinal axis, the first piston diameter is a maximum diameter of the central face portion and is less than an inner diameter of an inner wall of the barrel,
the first piston body further comprises a cylindrical portion oriented coaxially with the longitudinal axis, the cylindrical portion defining a first axial end, a second axial end, and a wall extending a distance along the longitudinal axis between the first axial end and second axial end, the wall defining a second piston diameter measured perpendicularly to the longitudinal axis, the second piston diameter is larger than the inner diameter of the barrel,
the annular curved portion extends between the first axial end of the cylindrical portion and the central face portion,
the annular curved portion comprises:
a first portion defining a curve and a diameter that is less than the second piston diameter; and
a second portion with a diameter that is substantially equal to the second piston diameter, the second portion of the annular curved portion extends a distance along the longitudinal axis,

the inert film defines an outer boundary that does not extend axially beyond the first axial end of the cylindrical portion to minimize contact between the inert film and the inner wall of the barrel, and
the distance that the wall of the cylindrical portion extends along the longitudinal axis is greater than the distance that the second portion of the annular curved portion extends along the longitudinal axis.

Assignees

• West Pharmaceutical Services Inc

Inventors

• Laubach Jeffrey M
• Brinkhues Jurgen
• Gruen Heike
• Worman Joel
• Zhao Xia
• Mattia Jason

Classifications

• A61M5/31513 Primary

  Piston constructions to improve sealing or sliding · CPC title

• A61M2205/0222

  Materials for reducing friction · CPC title