Powder-free corrosion copper plate is based on impact theory and thermal temperature difference theory, and it is the result of physical and chemical action.

The protective agent is added to the ferric chloride corrosive solution, and is evenly dispersed in the ferric chloride corrosive solution under mechanical stirring. During the corrosion process, it reacts with copper to form a thin protective film of white complex. Due to the different adhesion on the page, the purpose of corrosion is achieved through the vertical impulse of machinery.

in the process of corrosion, the etching solution with constant temperature generates heat of chemical reaction because the blank part of the copper plate is corroded, but the line part is not corroded and does not generate heat, so that the temperature difference of the plate is formed, and the boundary between the blank and the line is extremely poor, so that the protective force of the protective agent on the adsorbed plate is different, and it has corresponding resistance to impact and etching solution. The complex in the blank part of the copper plate was washed away by the impact, so that the blank part of the copper plate was corroded by ferric chloride corrosive solution. However, the side wall of the figure line still attached to the complex film because of the small impact force and played a protective role against corrosion. With the increase of time, the corrosion deepened to form a slope layer, and protruding patterns or lines were obtained, thus meeting the requirements of printing.

Deep copper plates without powder corrosion are mostly used for printing large quantities of printed parts, as well as anodized hot stamping and embossed products with beautiful packaging trademarks. The protective agent is prepared by heating and melting formamidine disulfide, vinyl thiourea and Pomei's 28-degree ferric chloride solution. The formula is as follows:

formamidine disulfide 49g

vinyl thiourea 18g

ferric chloride solution 125cc (Pomei 28 degrees)

above 22 liters, weighed by a protective agent. (1) Preparation before corrosion. Before corrosion, the corroded cabinet should be fully washed and cleaned, and the temperature and speed should be adjusted. The working status button should be adjusted to the preparation position, and the refrigerator should be connected with water. Prepare cleaning liquid, etc.

(2) corrosion: firstly, add 15 cc ~ 2 cc of hydrochloric acid into the corrosion machine, then add 2 liters of 28-degree ferric chloride solution and half of 65cc of protective agent, then the stirring temperature is reduced to below 24℃, and then start the machine and stir for 1 ~ 15 minutes before use.

brush the copper plate to be etched, and then use the cleaning liquid to distribute the plate and then etch it on the machine. Generally, the temperature should be controlled at 22℃ ~ 24℃, and the rotation speed should be controlled at 38 rpm ~ 45 rpm after the working conditions start. After 5 minutes of corrosion, stop the machine and quickly observe the corrosion of the copper plate. If there are no defects such as dirty spots, unsmoothness and abnormal slope, the corrosion can continue to the required depth. Clean the layout after etching.

To be prudent, a small piece of copper plate can be used as an etchant first, and the corrosion effect and state can be observed to determine the adjustment conditions, and then the printing plate can be corroded formally.

(3) whole page, that is, whole page is to trim the pockmarks of prints and cut off the redundant corners. The direct printing plate can be equipped with a bottom table, milled with a plate milling machine, or hollowed out a large space, and then printed on the computer. (1) The newly prepared ferric chloride corrosive solution is easy to make the copper plate layout lines thin and have a small slope, so it can be used after the old and new corrosive solutions are mixed half by half.

(2) When the protective agent is added, it should be increased or decreased according to the amount of copper rolled in the corrosive liquid. If new ferric chloride solution is used for corrosion, half of the protective agent should be added first, and the remaining half should be added gradually with the increase of the amount of copper corroded. If the old and new ferric chloride corrosive solutions are used in combination, a little less protective agent can be added. If the machine is shut down for 1 ~ 2 days and then started to corrode, it is better to add a quarter of the protective agent for the first time.

(3) A protective agent of the 22-liter corrosion machine should be replaced when the amount of copper corrosion reaches about 8～1g g..

(4) Adding a proper amount of hydrochloric acid into the etching solution can make the surface of etched copperplate prints smooth and the etching speed is also accelerated. If there is too little acid in the corrosive solution, the slope will be flat, not smooth, rough and slow to corrode. If there is too much acid in the etching solution, the layout will rot, and it should be adjusted accordingly according to the corrosion situation of the layout. Due to a variety of reasons, failures of one kind or another often occur in corrosion, so it is necessary to carefully analyze the reasons and solve them in time. Now, several common disadvantages in corrosion and their solutions are listed as follows:

① Small slope and literal shrinkage are caused by high temperature, high acidity and little protective agent.

② The steep slope and pockmarks are caused by low temperature and slow rotation speed.

③ Small size and large slope are the reasons for excessive protective liquid and slow rotation speed.

④ there are many pockmarks, which are caused by the uncleanness of the whole revision.

⑤ the idea rotted, which was caused by less protective agent and fast rotation speed.

⑥ Degumming film is caused by insufficient baking temperature and time and thin film.

⑦ The uneven slope is caused by the uneven corrosion machine or the different rotating speeds of the blades when stirring before and after.

an ideal printing plate requires a base angle of 12 ~ 13, a depth of 9 ~ 1 silk meters, smooth shoulders and floors, no shrinkage of lines, no paste between words, no pockmarks and no damage. This shows the importance of etching plate-making. Therefore, as a plate-making worker, we must follow the operating rules, make correct judgments when problems arise, and establish the correct ideas that plate-making serves printing and printing serves publishing, so as to do a good job in etching plate-making.