Browse Prior Art Database

Two Color Lithographic Relief Plate

IP.com Disclosure Number: IPCOM000078042D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 35K

Publishing Venue

IBM

Related People

Harris, RD: AUTHOR [+2]

Abstract

This two-color lithographic plate, formed by electrophoretic deposition, has nonimage areas that are recessed.

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Two Color Lithographic Relief Plate

This two-color lithographic plate, formed by electrophoretic deposition, has nonimage areas that are recessed.

The printing plate or cylinder is prepared by a method comprising the following steps:

A) Pretreat surface 1 (Fig. 1) of aluminum substrate 2 by conventional methods to clean it and improve its hydrophilic character.

B) Coat pretreated surface 1 to a thickness of the order of 0.001'' with conventional positive hydrophobic photoresist 3; i.e., one in which exposed areas solubilize in developer.

C) Expose photoresist 3 through photographic negative, not shown, to solubilize photoresist in image areas 4 where an oleophilic polymer 5 is to be deposited.

D) Remove exposed photoresist with developer to create areas 4 that will be printed with one color in conventional lithographic ink.

E) Electrophoretically deposit polymer 5 to a thickness similar to that of photoresist 3 on unprotected aluminum surface of areas 4; i.e., by a form of electrodeposition in which charged suspended colloidal polymer particles are coated onto a conductive substrate by use of a low direct-current voltage.

F) Dry plate 2,3,5; then reexpose through a positive transparency, not shown, to solubilize photoresist 3 covering what will become nonimage areas 6 of the plate while leaving, undeveloped, what will become a second set of image areas 7 that will be printed in a water-based ink. Ab G) Remove exposed photoresist, as in D to create nonimage areas...