Process for the surface treatment of aluminum support for printing plate

Abstract

Disclosed is a process for the surface treatment of an aluminum support for printing plate which comprises a step of brush-graining with an abrasive brush and an abrasive slurry, characterized in that as the abrasive there is used aluminum hydroxide, the aluminum hydroxide which has been used in graining is dissolved in a sodium aluminate solution and the sodium aluminate solution having a raised supersaturation degree, the aluminum hydroxide which has been left undissolved and seed crystal aluminum hydroxide undergo hydrolysis reaction to produce crystalline aluminum hydroxide which is then purified and recovered. The above process for the surface treatment of an aluminum support for printing plate can realize the reduction of the discharged amount of waste from the step of surface treatment of an aluminum plate as a lithographic printing plate support and the used amount of chemicals and abrasive to allow an extremely inexpensive stable production of an aluminum support for printing plate as compared with the prior art.

What is claimed is:  
     
         1 . A process for the surface treatment of an aluminum support for printing plate which comprises a step of brush-graining with an abrasive brush and an abrasive slurry, characterized in that as said abrasive there is used aluminum hydroxide, said aluminum hydroxide which has been used in graining is dissolved in a sodium aluminate solution and said sodium aluminate solution having a raised supersaturation degree, said aluminum hydroxide which has been left undissolved and seed crystal aluminum hydroxide undergo hydrolysis reaction to produce crystalline aluminum hydroxide which is then purified and recovered.  
     
     
         2 . The process for the surface treatment of an aluminum support for printing plate according to  claim 1 , wherein the percent dissolution of said aluminum hydroxide which has been used in abrasion in a sodium aluminate solution is from 15% to 100%.  
     
     
         3 . A process for the surface treatment of an aluminum support for printing plate which comprises preparing a part of a treatment liquid containing a sodium aluminate solution to be recycled for surface etching as a supersaturated sodium aluminate solution or mixing a part of said treatment liquid with an aluminum sludge mainly composed of amorphous aluminum hydroxide produced by the neutralization of waste acid liquid and waste alkaline liquid discharged from the step of surface treatment of an aluminum support to prepare a supersaturated sodium aluminate solution, and then allowing said sodium aluminate solution to undergo hydrolysis reaction to crystallize aluminum hydroxide which is then purified and recycled as an abrasive, characterized in that said aluminum hydroxide which has been used in abrasion is dissolved in a sodium aluminate solution and said sodium aluminate solution having a raised supersaturation degree, said aluminum hydroxide which has been left undissolved and seed crystal aluminum hydroxide undergo hydrolysis reaction to produce crystalline aluminum hydroxide which is then purified and recovered.  
     
     
         4 . The process for the surface treatment of an aluminum support for printing plate according to  claim 3 , wherein the percent dissolution of said aluminum hydroxide which has been used in abrasion in a sodium aluminate solution is from 15% to 100%.  
     
     
         5 . The process for the surface treatment of an aluminum support for printing plate according to  claim 3 , wherein the waste acid liquid and waste alkaline liquid discharged from the step of surface treatment of an aluminum support for printing plate were adjusted to a pH value of from not less than 5.0 to less than 9.0 when neutralized.