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Finger Print Resistant Top Coat for Direct Negative-Direct Plate

IP.com Disclosure Number: IPCOM000037775D
Original Publication Date: 1989-Jun-01
Included in the Prior Art Database: 2005-Jan-30
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Afzali-Ardakani, A: AUTHOR [+3]

Abstract

Disclosed is a formulation for the lubricating top coat of a Direct Negative-Direct Plate member, using a special class of organic polymers which contain both carboxylic acid and alkyl ester functionality.

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Finger Print Resistant Top Coat for Direct Negative-Direct Plate

Disclosed is a formulation for the lubricating top coat of a Direct Negative- Direct Plate member, using a special class of organic polymers which contain both carboxylic acid and alkyl ester functionality.

The lubricating top layer of electroNEG which consists of a mixture of graphite and hydroxyethyl cellulose, a water soluble polymer, suffers from rapid corrosion of the aluminum film in relatively high humidity and due to wet finger prints during handling. The ease of corrosion of the aluminum film has been found to be dependent on the hydrophilicity of the organic polymer present in the top coat mixture. On the other hand, when electroNEG is used with a direct plate, the top coat must have hydrophilic properties to prevent scumming of the non-image area.

By substituting for the binder (hydroxyethyl cellulose) in the top coat mixture, polyvinylmethylether maleic acid monobutyl ester (Gantrez ES 425-GAF Corp.) or polystyrylmaleic acid monobutyl ester (Scripset 550-Monsanto Co.), the surface of the electroNEG becomes hydrophobic which increases the corrosion resistance and archival life of the latter. When electroNEG is passed through a basic solution prior to mounting on the offset press (which process is necessary for present electroNeg as well as most conventional offset plates) the acid functionality of the binder is converted to corresponding alkali salt which makes the binder water soluble an...