Thick film compositions for making medical electrodes

• US 5,851,438 A
• Filed: 08/29/1997
• Issued: 12/22/1998
• Est. Priority Date: 08/29/1997
• Status: Expired due to Term

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Chan, Man-Sheung
• Primary Examiner(s): KOPEC, MARK T
• Application Number:
  US08/921,183
• Time in Patent Office: 480 Days
• Field of Search: 252/511, 252/514, 252/520.3, 106/1.14, 106/1.19, 524/439
• US Class Current: 252/514
• CPC Class Codes: A61N 1/0436 Material of the electrode
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys
• CPC Class Codes: H01B 1/24 the conductive material comprising carbon-silicon compounds, carbon or silicon

Abstract

The invention is directed to a conductive composition for iontophoretic electrodes comprising, based on solids: (a) 20-90% wt finely divided particles of silver, carbon, graphite and mixtures thereof; (b) 0-75% wt. finely divided particles of silver chloride; (c) 0.25-10% wt. hydrophilic polymer; and (d) 2-15% wt. hydrophobic thermoplastic polymer having a glass transition temperature (Tg)>40° C. The invention is also directed to compositions wherein the binder comprises 5-15% wt. copolymer of hydrophilic and hydrophobic monomers.

Claims

1. A conductive composition for iontophoretic electrodes comprising, based on solids:

(a) 20-90% wt. of silver particles;

(b) 0-75% wt. of silver chloride particles;

(c) 0.25-10% wt. hydrophilic polymer; and

(d) 2-15% wt. hydrophobic thermoplastic polymer having a Tg above 40°

C. said conductive composition further comprising a vehicle consisting of organic solvent or organic solvent mixtures.

2. The composition of claim 1 wherein the hydrophilic polymer is selected from the group consisting of poly(vinylpyrrolidone), poly(vinylpyrrolidone-vinyl acetate), poly(vinyl methyl ether), poly(ethylene oxide), poly(vinyl alcohol), poly(acrylamide), and poly(hydroxyalkyl methacrylate).

3. The composition of claim 1 wherein the hydrophobic polymer is selected from the group consisting of acrylic polymer, polyhydroxyether, poly(styrene-acrylonitrile), poly(vinylidene chloride-acrylonitrile), polyester, poly(acrylonitrile-butadiene-styrene).

4. The composition in claim 1 wherein the silver particles are in the range of 1-25 microns.

5. The composition in claim 1 wherein the silver chloride particles are in the range of 0.1-15 microns.

6. The composition in claim 1 further comprising conductive fillers selective from the group consisting of carbon and graphite.

7. The composition in claim 1 wherein the organic vehicle is selected from the group consisting of alkyl ketones, aromatic ketones, glycol alkyl ethers and their acetates, dibasic esters, n-methylpyrrolidone, butyrolactone, and aromatic solvents.

8. The composition of claim 1 wherein silver to silver chloride ratio is in the range of 100/0 to 80/20 by weight for iontophoretic anode.

9. The composition of claim 1 wherein silver to silver chloride ratio is in the range of 15/85 to 35/65 by weight for iontophoretic cathode.

10. The composition of claim 1 wherein the silver to silver chloride ratio by weight is in the range of 70/30 to 65/35.