Flexographic production process

1 rubber plate

Due to the different manufacturing processes, it can be divided into the following three methods:

1) Hand carving method. Commonly used in corrugated box printing, the screen is generally based on thick lines, large and small blocks, and coarse text. The content is simple and the printing requirements are not too high.

Production process:

Original image → Reverse image glue on rubber plate → Engraved version

The transparent original image is reversed on the surface of a certain size and flatness of the rubber plate, and the text image must be clear. The operator uses a sculpting knife of different size and shape, purely hand-skilled, removes the eraser of the non-printing part according to the outline of the character image, forms a sag, and the character image is retained as a printing plate.

2) mold rubber plate (this process is more complex. First make a metal plate (copper plate or zinc plate), then press the phenolic resin plate (similar to the letterpress version of the paper version), also known as the master. Then cover the master plate with a rubber plate, The use of special equipment by high temperature, high pressure processing, rubber vulcanization in the master mold, cooling, after grinding and smoothing, that is a rubber plate.

Molding rubber plate production process:

Manuscript → negative film negative film → dried metal plate → pressed phenolic resin plate → high temperature and high pressure to produce rubber plate → thickness measurement → trim the back of the rubber plate.

3) The laser engraving method adopts photoelectric scanning, analog-to-digital conversion, and a laser engraving head to automatically engrave a rubber plate. When engraving, according to the graphic data on the rubber plate carved into different depths of the layout, a printing plate. The method can produce a cable version, especially for seamless sleeve printing plate production, more suitable.

2 photosensitive resin plate

Can be divided into two kinds of solid photosensitive resin plate and liquid photosensitive resin plate. Two types of plates have different compositions, different manufacturing processes, and some differences in performance, but the scope of application is the same.

l) Liquid photosensitive resin plate. At the time of plate making, a photosensitive resin is pre-coated on a specific exposure apparatus. The exposure device is composed of upper and lower precision glass plates, upper and lower ultraviolet light sources, etc. so that the printing plate can be exposed positively and backwardly.

* Apply liquid resin, perform main exposure and back exposure.

As shown in Fig. 1, when the liquid resin is coated, the emulsion of the negative image is faced upwards, placed on the lower glass, covered with a thin film, and a vacuum is applied to protect the film from close contact with the vaginal image (on the cover film). The photosensitive resin solution was placed on the resin layer, and the substrate was placed on the resin layer.The upper glass was placed down so that the photosensitive resin layer was sandwiched between the two glass plates.Figure 2 shows the backside exposure and main exposure device. The backside exposure makes the substrate and resin bond Strong;When the main exposure, the light shines through the negative on the photosensitive resin layer, the resin in the light-receiving part hardens into a solid state, and the photosensitive resin in the non-light-receiving place is still in a liquid state, so the exposed plate can be placed on a tilt In a recovery tank, the unexposed excess resin on the plate is recycled.

Figure 1 Coating liquid photosensitive resin

Figure 2 Exposure device

※Flush (develop ).

For the exposed plate, use a special brush to brush off the remaining photosensitive resin solution in the machine slot, as shown in Figure 3. The washed plate is dried in an oven and then subjected to post-exposure treatment to completely harden the resin on the plate.

Figure 3 Flush development

There are not many liquid versions used in the domestic flexo printing industry, and they are only applied to corrugated cartons. It has the problems of limited format, low resolution, and poor hand feel. It is not suitable for producing fine image plates.

2) Solid photosensitive resin plate. This is a pre-coated version, just like the PS version used for lithography. Usually should be stored in a light-proof cardboard box. When used, it is very convenient to remove the cut from the box according to the size of the plate.