Corrosion technology of copper plate making

Copperplate making occupies a pivotal position in letterpress printing, packaging printing, and anodized aluminum hot stamping. The plate-making process is relatively complicated. To make a printing plate that meets the printing requirements, you must be familiar with the process and strictly control each link, otherwise it is easy to cause quality accidents. The process operation is briefly described as follows:

1. Mesh copperplate corrosion plate making

1. Plate selection

The required thickness of the plate is 0.8~2.0mm, and the commonly used one is 1.0~1.6mm. The copper plate for plate making is a special plate material, which contains chromium, strontium, silver and other metals. It is easier to corrode than pure copper. Generally, when choosing a copper plate for corrosion, it is required to be free of impurities, streaks, smooth surface and moderate hardness.

2. Preparation of corrosive liquid (ferric chloride liquid)

The main component of the corrosive solution is ferric chloride, which is a compound of iron oxide and hydrochloric acid.

Yellow solid or dark-brown crystal, very easy to deliquesce. When the plate is corroded, it is dissolved into a golden yellow liquid with water to produce a replacement oxidation-reduction effect with copper.

Corrosion solution preparation: Dissolve ferric chloride in water to the required concentration. A concentration of

Pomei 35 ~ 40 degrees, and filtered and clarified.

The prepared ferric chloride liquid has a sweet taste, if you can smell it has a pungent taste of hydrochloric acid

Time, it means that the acidity in the ferric chloride solution is too high, and it is necessary to use old corrosive liquid or three with low acidity.

Reconciled with ferric chloride liquid.

3. Cleaning fluid configuration

The role of the cleaning solution is to clean the impurities on the copper plate surface, so that the copper and the ferric chloride are in good contact, so as to obtain a better corrosion effect. Before and after the corrosion, the cleaning solution should be used to treat the clean layout. Cleaning solution preparation: 50cc glacial vinegar, salt, hydrochloric acid, water 150g, 25cc, 500cc

The above-mentioned various medicines can be increased or decreased appropriately, but it should be noted that the hydrochloric acid should not be too mixed, so as not to affect the film.

4. Print

Exposure is to expose the photosensitive film coated on the copper plate surface. The photosensitive film is a mixture of animal glue or resin and other polymer compounds and dichromate. This photosensitive glue is insoluble in water after exposure, and soluble in water at unexposed areas, so that the copperplate layout will show the lines and dots of the composite original, and then it will become corrosion-resistant enamel after heating and baking, which meets the requirements of letterpress plate making .

Exposure is an important process in the platemaking process. He has very strict requirements on the negatives of the mesh photography. Generally, the high-profile parts (high light out) of the image are required to be transparent. If the low-key part of the image (darkness) is above 0.5~1, it is appropriate to shoot the small black dots. The dots should be black or round, and small and solid reflective dots must be photographed so that the layout can show the gradation after corrosion.