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Light Induced Hydrophilicity (Wettability) and its Application to Photocopying and Offset Printing

IP.com Disclosure Number: IPCOM000089389D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 4 page(s) / 57K

Publishing Venue

IBM

Related People

Aviram, A: AUTHOR

Abstract

Modern offset printing is a photographic process in which the design is photographed onto a positive plate. The resulting printing plate is utilized for printing by the planographic method, namely, printing from a flat surface which has the properties of attracting moisture over the nonprint area and holding greasy ink over the hydrophobic printing area. Naturally, water and oil will not mix and this property is exploited to address the ink only to the printing characters and images.

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Light Induced Hydrophilicity (Wettability) and its Application to Photocopying and Offset Printing

Modern offset printing is a photographic process in which the design is photographed onto a positive plate. The resulting printing plate is utilized for printing by the planographic method, namely, printing from a flat surface which has the properties of attracting moisture over the nonprint area and holding greasy ink over the hydrophobic printing area. Naturally, water and oil will not mix and this property is exploited to address the ink only to the printing characters and images.

Novel materials that change their properties as water repellent (nonpolar, hydrophobic) to water attractant (polar, hydrophilic) when they are exposed to light are described herein. Thus, these materials are candidates for instant offset plates, and can be utilized for direct photocopying processes when incorporated in suitable machines.

Furthermore, the chemical reaction that is responsible for the change (hydrophobic to hydrophilic) is reversible both chemically or electrochemically, and thus the materials should be reuseable in cycles.

The basic chemical reaction is as shown below.

(Image Omitted)

for Y materials like CCl(4), CBr(4), CHI(3) or other polyhalogenated compounds. This is a very well established and general reaction. Its important features are that charged species X/+/ are formed when it takes place, and these charged species are water soluble while the starting material...