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Surface treatment methods and characteristics of aluminum substrates

Surface treatment methods and characteristics of aluminum substrates

A. Skill requirements for aluminum substrates
The most basic skill requirement for the aluminum substrate of the PS plate is to have a smooth and flat surface, no scratches, pits, marks, non-metallic shoe press-in, pores, rolled stripes and other apparent defects. The thickness is consistent, and the wave level is controlled. Within 1mm, the straightness is less than 2I; the structure is fine and uniform, without segregation, slag inclusion, and the internal stress is symmetrical and uniform; the roughness Ra value is less than 0.28 to ensure that the electrolytic sand is fine and uniform. At present, many board-based materials used in our country are 1050A, 1060 and so on.
B alkaline washing
Generally, the aluminum plates supplied by aluminum processing plants have a certain amount of oil on their surface. Oil and oxide film have an impact on the disposal of sand mesh. In the production of PS plates, hot alkali is often used to wash the aluminum plates for surface treatment.
Generally, lye is used to remove the oxide film and oil. Commonly used oil removal liquid ratio is: NaOH quality sodium and other corrosion inhibitors and sodium gluconate, fatty acid polyoxyethylene ethers solubilizing, complexing and other surface active agents.
The temperature of the degreasing liquid is generally controlled at about 55-60°C, and the effect of degreasing is related to the temperature of the solution. If the temperature is too high, it will severely corrode the aluminum substrate, so it is necessary to control the temperature.
The timing of degreasing must be determined through careful comparison. Because it is related to various different production lines. The reel production line is related to the speed of the production line. Taking 4m/min as an example, the oil removal time must be 20s to ensure its function.
It is necessary to pay attention to the timely update of the oil removal process. Because a lot of saponification, emulsification and aluminum salts are generated during the oil removal process, their presence affects the oil removal effect and prevents the saponification and emulsification of the oil on the surface of the aluminum plate. When the oil is not strong, it is necessary to update it in time. Generally, if the alkali pump is circulated, the degreasing liquid can last for a longer time, and if it is not circulated, the update time will be shortened.
The easiest way to see the degreasing effect is to use water. The surface water of the aluminum plate with good oil removal effect can be evenly attached and loosened. If the water is poured on the surface of the aluminum plate, the surface of the aluminum plate is in the shape of water droplets, indicating that the oil removal effect is not good. Always pay attention to the temperature of degreasing. If the temperature of the degreasing liquid is too low, it can constitute incomplete degreasing.
C pickling
In the production process, there is a nitric acid pickling process after the alkaline washing, the purpose of which is to remove the residual material after the alkaline washing and neutralize the remaining lye. The mass concentration of the nitric acid solution is 5% to 10%. When preparing, pour nitric acid into the water carefully and mix thoroughly. In the pickling process, you should always pay attention to the concentration analysis of the solution and make up in time.
D Coarse
The roughening is to form a grit structure with required roughness. Roughening can improve the water affinity of the aluminum substrate surface, increase the wetting amount of the surface of the substrate, and avoid dirt on the plate; the roughened appearance can also improve the adhesion of the plate to the sensitizer, thereby improving the printing resistance of the printing plate. force.
The roughened sand mesh is composed of countless peaks and valleys. The different sand mesh structure has a greater impact on the adhesion of the water-retaining photosensitive layer and has a greater impact on the use of the PS plate. The characteristic parameters of the profile curve of the sand mesh rough section made by the surface roughness tester are used to characterize the production roof


Post time: Mar-10-2022