Aluminum is widely used in lithography because of its light weight, excellent mechanical strength, surface treatment and corrosion resistance. The aluminum plate used for lithography is a 0.1-0.3mm thick sheet, containing jis1050 pure aluminum (aluminum purity is not less than 99.5%) and jis1100 aluminum (containing 0.05-0.2% copper). These aluminum plates are usually mechanically, chemically or electrochemically ground, then coated with a photosensitive material, and then exposed and developed into printed plates.
After the above processing, the printed board is then installed on the pressing roller, and the image area coated with the fountain solution is brushed with ink, then the ink is transferred to the rubber roller for imaging, and then printed on the paper. The printing life of this kind of printed board can reach 30000 pieces. Its rough surface enhances the adhesion of photosensitive materials and the retention of water in printing and further color reproduction. These characteristics are indispensable requirements for aluminum plate to play the role of printed board. In order to increase the printing life, the aluminum plate needs to be anodized after plate grinding to form a layer of anodized film with a thickness of about 1-3 μ m, and then coated with photosensitive material, and then exposed and developed to prepare for making a printing plate.
The printing life of the anodized printed boards can reach about 70000 ~ 150000 pieces. the above-mentioned aluminum plate for printing shall have the following characteristics:
A plate grinding can form a uniform rough surface;
B photographic material has excellent adhesion performance;
C prevent the paste plate without image area in printing;
D image area has excellent color reproduction performance;
E after developing, the study of image area found that the color of paper base was white, which was easy to see the drawing part.