Moisture barrier composite film of silicon nitride and fluorocarbon polymer and its use with an on-cell tester for an electrochemical cell

• US 5,925,479 A
• Filed: 08/05/1996
• Issued: 07/20/1999
• Est. Priority Date: 01/23/1995
• Status: Expired due to Term

• Current Assignee: Gillette Company (The Procter & Gamble Company)
• Original Assignee: Duracell Incorporated (Berkshire Hathaway Incorporated)
• Inventors: Wei, Guang, Lagos, Bryan Christopher, Treger, Jack
• Primary Examiner(s): SERGENT, RABON A
• Application Number:
  US08/695,277
• Time in Patent Office: 1,079 Days
• Field of Search: 428/421, 428/422, 428/446, 428/451, 156/275.5, 156/307.1, 427/527, 427/569, 427/579, 427/582, 427/583, 427/585, 427/588, 427/255.6, 427/372.2, 324/426, 324/433, 324/435, 324/76.11, 429/91, 429/90, 429/92, 429/93
• US Class Current: 429/91
• CPC Class Codes: C08J 7/0423 with at least one layer of inorganic material and at least one layer of a composition containing a polymer binder
• CPC Class Codes: C08J 7/048 Forming gas barrier coatings
• CPC Class Codes: H01M 10/488 Cells or batteries combined with indicating means for external visualization of the condition, e.g. by change of colour or of light density
• CPC Class Codes: H01M 50/119 Metals
• CPC Class Codes: H01M 50/121 Organic material
• CPC Class Codes: H01M 50/124 having a layered structure
• CPC Class Codes: H01M 50/598 Guarantee labels
• CPC Class Codes: H01M 6/505 Cells combined with indicating means for external visualization of the condition, e.g. by change of colour or of light intensity
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y10T 428/3154 Of fluorinated addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31544 Addition polymer is perhalogenated
• CPC Class Codes: Y10T 428/31667 Next to addition polymer from unsaturated monomers, or aldehyde or ketone condensation product

Abstract

A light transparent moisture barrier useful for preventing moisture from destroying the effectiveness of a moisture sensitive cell condition tester on an electrochemical cell, comprises a plurality of very thin layers of amorphous silicon nitride and a hydrophobic fluorocarbon polymer on a flexible, polymeric substrate. The layers are formed on the substrate by a deposition process such as sputtering. The thickness of any individual layer is less than one micron.

Claims

1. A label/tester composite for an electrochemical cell, said composite comprising a label and an electrochemical tester in contact with said label, said tester having a light transparent moisture barrier for protecting said tester from moisture, wherein said moisture barrier comprises a composite on a polymeric substrate, said moisture barrier composite comprising at least one layer of amorphous silicon nitride and at least one layer of a hydrophobic fluorocarbon polymer, alternately deposited over each other, wherein the thickness of said silicon nitride and fluorocarbon polymer layers ranges between about 250 to 2500 angstrom and between about 250 angstrom to about 1 micron, respectively, and wherein said moisture barrier is no greater than one and one half mils thick.

2. The label/tester composite of claim 1 wherein said moisture barrier composite comprises at least two layers of said silicon nitride and at least two layers of said fluorocarbon polymer.

3. The label/tester composite of claim 2 in which the layers of said moisture barrier closest to said label are polymeric.

4. The label/tester composite of claim 1 in which the thickness of each of the fluorocarbon polymer layers is between about 300 and 5,000 angstroms.

5. The label/tester composite of claim 1 in which said moisture barrier has water vapor permeability of less than 8 micrograms of water per square inch of surface area over a twenty four hour period.

6. The label/tester composite of claim 5 wherein said fluorocarbon polymer comprises at least one polymer selected from the group consisting of (i) polytetrafluoroethylene (PTFE), (ii) copolymers of tetrafluoroethylene (TFE) with hexafluoropropylene, (iii) copolymers of TFE with perfluoro(alkyl vinyl ethers), and (iv) polymers formed by reacting 2,2-bistrifluoromethyl-4,5 difluoro 1,3dioxole (PDD) with at least one monomer selected from the group consisting of PDD, TFE, vinylidene fluoride, chlorotrifluoroethylene, vinyl fluoride, perfluoro(alkyl vinyl ethers) and mixtures thereof.

7. The label/tester composite of claim 6 wherein said fluorocarbon polymer is formed by reacting said PDD with at least one monomer selected from the group consisting of PDD, TFE, vinylidene fluoride, chlcrotrifluoroethylene, vinyl fluoride, perfluoro (alkyl vinyl ethers) and mixtures thereof.

8. The label/tester composite of claim 7 wherein said fluorocarbon polymer is a reaction product of said PDD and said TFE.

9. The label/tester composite of claim 5 wherein said moisture barrier composite comprises alternating layers of said silicon nitride and said fluorocarbon polymer.

10. The label/tester composite of claim 9 wherein said fluorocarbon polymer comprises at least one polymer selected from the group consisting of (i) PTFE, (ii) copolymers of TFE with hexafluoropropylene, (iii) copolymers of TFE with perfluoro(alkyl vinyl ethers), and (iv) polymers formed by reacting 2,2-bistrifluoromethyl-4,5-difluoro- 1,3-dioxole (PDD) with at least one monomer selected from the group consisting of PDD, TFE, vinylidene fluoride, chlorotrifluoroethylene, vinyl fluoride, perfluoro(alkyl vinyl ethers) and mixtures thereof.