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Improved Electrolyte for Electrolytic Printing

IP.com Disclosure Number: IPCOM000045054D
Original Publication Date: 1983-Jan-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Bernier, WE: AUTHOR [+2]

Abstract

Earlier work with electrolytic printing systems has considered only potassium and ammonium bromide salts as the conductive medium and oxidant-catalyst system in the electrolyte. Other minor component additives have been added to contribute to other aspects of printing behavior, such as buffering (phosphate salts) or print stability (fluoride salt to stabilize starch-iodide printing). It is possible, however, to separate the electrolyte functions of conductivity and oxidant-catalyst to a certain extent and, thus, introduce alternate bromide salts and additional conductive salts to the electrolyte system to replace potassium bromide in equivalent amounts, thereby lowering the overall cost without sacrificing performance.

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Improved Electrolyte for Electrolytic Printing

Earlier work with electrolytic printing systems has considered only potassium and ammonium bromide salts as the conductive medium and oxidant-catalyst system in the electrolyte. Other minor component additives have been added to contribute to other aspects of printing behavior, such as buffering (phosphate salts) or print stability (fluoride salt to stabilize starch-iodide printing). It is possible, however, to separate the electrolyte functions of conductivity and oxidant-catalyst to a certain extent and, thus, introduce alternate bromide salts and additional conductive salts to the electrolyte system to replace potassium bromide in equivalent amounts, thereby lowering the overall cost without sacrificing performance.

A variety of alkali bromide salts can also be used. Li/+/, Na/+/, Rb/+/ and Cs/+/ all provide sufficient conductivity for printing. Print intensity is sensitive to the mobility of the cation electric field. The optimum printing is achieved with K/+/, Rb/+/ and CS/+/. Mixtures of any of these, with a fraction of Na/+/, can still produce adequate printing as long as a significant fraction of highly mobile ions still remains.

A number of additional salts can be added to the electrolyte, replacing potassium bromide in either binary mixtures of multicomponent systems. Potassium nitrate, sodium nitrate, and sodium sulfate can be mixed with either sodium bromide or potassium bromide salt necessary in effective electrolyte system. The amount of bromide salt necessary in the system the system varies from 5-100% (mole percent) with an optimum range of 40-70%. Potassium and sodium nitrates are the major components making up the difference. Sodium sulfate can be added as a minor component. Examples of mixed electrolyte systems are given below. Substitution of NO/3/-/ and SO/4/2-/ for Br/-/ reduces the corrosiveness of the electrolyte system.

Absolute amounts of electrolyte coated on pretreated paper may vary according to coating method, but ratios remain the same. The ph of the system is adjusted with phosphate buffer and KOH to pH>7.

EXAMPLE 1 Component Mole fraction (%)

KBr 40 Approximately...