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A Phosphate Complex of Ferric Chloride as a Thermal Recording Compound

IP.com Disclosure Number: IPCOM000097400D
Original Publication Date: 1962-Nov-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Damm, EP: AUTHOR

Abstract

Phosphate complexes of ferric chloride can be used as thermally sensitive recording compounds. The mechanism of recording is: (1) The hydrolysis of these complexes occurs at elevated temperatures to produce localized acidic areas. (2) At the elevated temperatures, the acid produced causes premature charring of the cellulose.

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A Phosphate Complex of Ferric Chloride as a Thermal Recording Compound

Phosphate complexes of ferric chloride can be used as thermally sensitive recording compounds. The mechanism of recording is:
(1) The hydrolysis of these complexes occurs at elevated

temperatures to produce localized acidic areas.
(2) At the elevated temperatures, the acid produced causes

premature charring of the cellulose.

When phosphoric acid is added to a solution of ferric chloride, a bleaching of the yellow ferric chloride solution results because of the formation of a phosphate complex. Card stock coated with this solution is colorless when dried, but turns to a permanent brown-black at temperatures above 130 degrees centigrade. Neutralization of the solution to a pH of about 5 before coating gives a somewhat lighter color to the heated document.

A gelatin and ethyl cellulose combination serves as a good coating base for these compounds. The ethyl cellulose acts as an acid absorber which chars instead of the base document. This, in addition to the fact that the thermally sensitive compound is fixed on or near the surface of the document by the binder serves to reduce document tendering.

As an alternative approach, the phosphate complex can be placed selectively on the paper by any printing technique and the entire document heated.

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