Aluminum alloy sheet for lithographic printing plate

Abstract

The present invention provides an aluminum alloy sheet for a lithographic printing plate which allows pits to be uniformly formed by electrochemical roughening, and excels in strength and heat softening resistance. The aluminum alloy sheet for a lithographic printing plate includes 0.1-0.3% of Mg, more than 0.05%, but 0.5% or less of Zn, 0.2-0.6% of Fe, 0.03-0.15% of Si, 0.02% or less of Cu, and 0.003-0.05% of Ti, the remainder being Al and impurities. The aluminum alloy sheet may include more than 0.05%, but 0.3% or less of Mn.

Description

BACKGROUND OF TED INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an aluminum alloy sheet for a lithographic printing plate. More particularly, the present invention relates to an aluminum alloy sheet for a lithographic printing plate which con be uniformly roughened on the surface by electrochemical etching and exhibits excellent strength and heat softening resistance. [0003] 2. Description of Background Art [0004] An aluminum alloy sheet is generally used as a support for a lithographic printing plate (including offset printing plate) A support is roughened on the surface from the viewpoint of improving adhesion to a photosensitive film and water retention properties in a non-image area. [0005] As the surface roughening method, a mechanical roughening method ouch as ball graining, brush graining, or wire graining has been conventionally used. As the support, a JIS A1100 alloy (aluminum purity: 99.0%), a JIS A3003 alloy (aluminum purity: 98.0-98.5...

AI Technical Summary

Benefits of technology

[0012] In order to obtain an aluminum alloy sheet used as a support for a printing plate which can deal with strong demands for adhesion to the photosensitive film and water retention properties in the non-image area, further increase uniformity of pits formed by surface roughening, and satisfy demands for high strength and burning resistance, the present inventors have conducted further diversified studies on relevance of the content of components and the relationship among the components of the aluminum alloy support based on a JIS A1050 equivalent material with the above-described properties. As a result, the present inventors have found that the strength and heat resistance can be improved and excellent roughening properties can be obtained by adding Mg and Zn in specific amounts.

[0013] The present invention has been achieved based on the above findings. An object of the present invention is to provide an aluminum alloy sheet for a lithographic printing plate which allows formation of extremely uniform pits on the surface by electrochemical roughening to ensure further excellent adhesion to the photosensitive film and water retention properties, and excels in strength and burning resistance.

Problems solved by technology

However, the above aluminum alloy sheet used as a support cannot entirely satisfy demands for uniform formation of pita by electrolytic roughening using the hydrochloric acid electrolyte or nitric acid electrolyte, high strength, and burning resistance, and does not necessarily have sufficient characteristics to deal with strong demands for adhesion to the photosensitive film, water retention properties in the non-image area, and the like.