Syringe plunger

• US 20100280370A1
• Filed: 07/12/2010
• Published: 11/04/2010
• Est. Priority Date: 03/26/2009
• Status: Abandoned Application

• Current Assignee: David Namey Jr
• Original Assignee: David Namey Jr
• Inventors: Namey, David JR.
• Application Number:
  US12/804,064
• Publication Number:
  US 20100280370A1
• Time in Patent Office: Days
• US Class Current: 600/432
• CPC Class Codes: A61M 5/31511 Piston or piston-rod constructions, e.g. connection of piston with piston-rod A61M5/5066 takes precedence
• CPC Class Codes: A61M 5/31515 Connection of piston with piston rod
• CPC Class Codes: B29C 45/1676 using a soft material and a rigid material, e.g. making articles with a sealing part
• CPC Class Codes: B29L 2031/7544 Injection needles, syringes

Abstract

A syringe plunger is manufactured by injecting polypropylene with filler into a mold for forming the hard core of the plunger, and immediately thereafter co-injecting a thermoplastic elastomer into a cover mold positioned at the forward end of the plunger mold cavity to thereby form a soft exterior cover over the forward end of the hard plunger core with a secure chemical bond.

Claims

1. A syringe plunger comprising:

a hard core composed of polypropylene and filler; and

a soft exterior cover of thermoplastic elastomer molded in contact with a forward end of said core by co-injection during molding of said core, whereby said soft exterior is chemically bonded, as opposed to a mere molecular bond, to said hard core as a consequence of said co-injection process of said core and cover compositions.

2. The syringe plunger of claim 1, wherein said filler consists of at least one of glass fiber, mica, calcium carbonate or talc.

3. The syringe plunger of claim 1, wherein said hard core has a hollow interior cavity which is open to a rearward end of said core and no exterior cavities are provided for mechanical bonding with said elastomer.

4. The syringe plunger of claim 3, including a molded hard plastic plunger stem dimensioned to fit and secure in said cavity with a force fit.