Chemically stabilized film

• US 4,726,997 A
• Filed: 08/26/1986
• Issued: 02/23/1988
• Est. Priority Date: 08/26/1986
• Status: Expired due to Term

• Current Assignee: Cryovac Incorporated (Sealed Air)
• Original Assignee: W R Grace & Company Cryovac DIV
• Inventors: Schirmer, Henry G., Mueller, Walter B.
• Primary Examiner(s): HERBERT JR, THOMAS
• Application Number:
  US06/900,576
• Time in Patent Office: 546 Days
• Field of Search: 428/35, 428/216, 428/480, 428/483, 156/244.11, 156/244.23, 264/211.23, 264/211
• US Class Current: 428/480
• CPC Class Codes: A61J 1/10 Bag-type containers
• CPC Class Codes: B32B 2439/80 Medical packaging
• CPC Class Codes: B32B 27/18 characterised by the use of special additives
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: B32B 9/045 of synthetic resin
• CPC Class Codes: Y10T 428/31786 Of polyester [e.g., alkyd, etc.]
• CPC Class Codes: Y10T 428/31797 Next to addition polymer from unsaturated monomers

Abstract

In a multilayer flexible film suitable for medical solution packaging, film-derived extractables are controlled by the use of a small amount of a high molecular weight stabilizer in the outer layer of the film. Solution pH can be controlled by the addition of a carbonate of an alkali metal to at least one intermediate adhesive layer and/or the core layer of the film.

Claims

1. In a multilayer flexible film comprising a sealant layer, a core layer comprising very low density polyethylene, an outer layer of a flexible polyester or copolyester, a first adhesive layer bonding the core layer to the sealant layer, and a second adhesive layer bonding the core layer to the outer layer, the improvement comprising the inclusion in the outer layer of between about 0.3% and 1% by weight of the outer layer of a high molecular weight stabilizer.

2. The improvement according to claim 1 wherein the outer layer includes about 0.7% of a high molecular weight stabilizer.

3. A method of producing a multilayer film comprising:

(a) blending a flexible polyester or copolyester with between about 0.3% and 1%, by weight of the polyester or copolyester, of a high molecular weight stabilizer; and

(b) coextruding a multilayer film comprising a sealant layer, a core layer comprising very low density polyethylene, an outer layer containing the blend of (a), a first adhesive layer bonding the core layer to the sealant layer, and a second adhesive layer bonding the core layer to the outer layer.

4. The method according to claim 3 wherein about 0.7% of a high molecular weight stabilizer is blended with the polyester or copolyester prior to extrusion.