Aluminum strip for lithographic printing plate carriers and the production thereof

Abstract

A method for producing aluminum strips for lithographic printing plate supports, wherein the aluminum strip is produced from a rolling ingot, which after optional homogenizing is hot-rolled to a thickness of 2 mm to 7 mm and cold-rolled to a final thickness of 0.15 mm to 0.5 mm provides for an aluminum strip having a thickness of 0.15 mm to 0.5 mm and a printing plate support produced from the aluminum strip.

1 . A method for producing aluminum strips for lithographic printing plate supports, wherein the aluminum strip is produced from a rolling ingot, which after optional homogenising is hot-rolled to a thickness of 2 to 7 mm, and by cold-rolling the hot strip the aluminum strip is cold-rolled to a final thickness of 0.15 to 0.5 mm, wherein the aluminum strip comprises an aluminum alloy including the following alloying constituents in weight percent:
 0.3%≦Fe≦0.4%,   0.25%≦Mg≦1.0%,   0.05%≦Si≦0.25%,
 Mn≦0.1%, 
 Cu≦0.04%, 
   
       with the remainder Al and unavoidable impurities, individually max. 0.05%, in total max. 0.15%; during cold-rolling an intermediate annealing at a thickness of 1.5 mm to 0.5 mm is carried out and the aluminum strip is then rolled to a final thickness of 0.15 mm to 0.5 mm by cold-rolling and is coiled in a hard-as-rolled state for further processing into a lithographic printing plate support. 
     
     
         2 . The method according to  claim 1 , wherein the aluminum alloy has a Mg content of 0.4 wt. % to 1.0 wt. %. 
     
     
         3 . The method according to  claim 1 , wherein the aluminum alloy has a Mg content of 0.25 wt. % to 0.6 wt. %. 
     
     
         4 . The method according to  claim 1 , wherein the aluminum alloy has a Ti content of max. 0.05 wt. %, a Zn content of max. 0.05 wt. % and a Cr content of less than 100 ppm. 
     
     
         5 . The method according to  claim 1 , wherein the hot-rolling takes place at a temperature of 250° C. to 550° C., wherein the hot-rolling final temperature is 280° C. to 350° C. 
     
     
         6 . The method according to  claim 1 , wherein during intermediate annealing the metal temperature is 200° C. to 450° C. and the aluminum strip is held at the said metal temperature for at least one to two hours. 
     
     
         7 . An aluminum strip for producing lithographic printing plate supports, having a thickness of 0.15 mm to 0.5 mm, wherein the aluminum strip comprises an aluminum alloy including the following alloying constituents in weight percent:
 0.3%≦Fe≦0.4%,   0.2%≦Mg≦1.0%,   0.05%≦Si≦0.25%,
 Mn≦0.1%, 
 Cu≦0.04%, 
   
       with the remainder Al and unavoidable impurities, individually max. 0.05%, in total max. 0.15%, and
 wherein the aluminum strip has a reversed bending fatigue strength transverse to the rolling direction of at least 2,320 cycles in a hard-as-rolled state in the reversed bending test. 
 
     
     
         8 . The aluminum strip according to  claim 7 , wherein the aluminum strip has a tensile strength of up to 200 MPa in a hard-as-rolled state longitudinal to the rolling direction and a tensile strength of at least 145 MPa after a burning-in process longitudinal or transverse to the rolling direction. 
     
     
         9 . The aluminum strip according to  claim 7 , wherein the aluminum alloy has a Mg content of 0.25 wt. % to 0.6 wt. %. 
     
     
         10 . The aluminum strip according to  claim 7 , wherein the aluminum alloy has a Mg content of 0.4 wt. % to 1.0 wt. %. 
     
     
         11 . The aluminum strip according to  claim 7 , wherein the aluminum alloy has a Ti content of max. 0.05 wt. %, a Zn content of max. 0.05 wt. % and a Cr content of less than 50 ppm. 
     
     
         12 . The aluminum strip according to  claim 7 , wherein the aluminum alloy has a thickness of 0.25 to 0.5 mm. 
     
     
         13 . (canceled) 
     
     
         14 . The method according to  claim 1 , wherein the aluminum strip comprises Mn≦0.05%. 
     
     
         15 . The aluminum strip according to  claim 7 , wherein the aluminum strip comprises Mn≦0.05%.