Analysis of Cigarette Box With Offset Printing capillary film production screen technology

Analysis of Cigarette Box With Offset Printing capillary film production screen technology

The drying temperature is strictly controlled

Drying temperature should be controlled 35 ~ 40℃, not higher than 40℃, this temperature is the actual temperature on the screen, not the indicated temperature on the equipment. When the actual temperature on the screen is greater than 40℃, it will speed up the dark reaction of the photosensitive adhesive layer, the longer the drying time, the deeper the degree of dark reaction, which leads to the difficulty of developing after exposure, and even can not show the pattern, and even cause it is difficult to recover the screen.

Complete removal of moisture

If the photographic film is not thoroughly exposed, even if the exposure time is just right, but because of the residual moisture in the photographic adhesive layer, it will affect the penetration of ultraviolet light, so that the photographic film is underexposed, affecting the printing resistance of the screen, causing the edge of the pattern to produce burr, photographic adhesive layer thinning. Serious, in the development process, the film will even be washed away. Therefore, it is very important to control the thickness of the photographic film thoroughly and ensure the quality and printing resistance of the screen.

It is worth noting that after the photographic film is dried to remove the protective film base (PET film), it must be dried again at the same temperature, so that the water in the adhesive film of the transparent PET film and the photographic film can be further removed before exposure. For the prior posted after drying without removing the PET sheet base and storage of the screen, before exposure must be dry, in order to make the screen on the photosensitive adhesive layer in the air to absorb the moisture removed together, more conducive to improving the quality of the screen.

How to judge whether the drying is complete?

(1) After the capillary film is dry, it is very easy to remove the transparent film (PET), and there is no harsh sound, and the surface of the photosensitive film is bright, indicating that the photosensitive film has been completely dry, and vice versa.

(2) After exposure, out of the vacuum state of the printing machine for a moment, the printing film can be smoothly separated from the photographic film on the screen or automatic separation, which indicates that the photographic film has dried, otherwise not dry.

Control of exposure

When the exposure is insufficient, if the film is not completely hardened, the pattern on the screen is easy to deform during the development, the image definition is poor, the dot loss, the printing resistance is reduced, and the screen is easy to produce pinholes and sand holes; After the screen is recovered, the shadow of the original image and text is left on the screen. And the exposure is excessive, the screen plate development is difficult, the resolution of the image drops, or the image can not be developed at all. Therefore, the amount of screen exposure must be just right to ensure that the original manuscript achieves 100% reduction as far as possible. Therefore, the exposure time should be determined according to the operating conditions, such as ambient temperature, humidity, working voltage, the performance and quality of the UV lamp tube of the exposure machine, the wavelength of the emission of UV light and its use time, the quality and batch of the capillary film, and so on. In addition, the exposure before exposure is detected by the exposure slide rule, which can easily determine the correct exposure time.

Selection of capillary film

The reasonable matching of the thickness of the capillary film and the number of mesh mesh is also a key technology to ensure the quality of the screen. The thickness of the capillary film and the number of mesh mesh can be determined by referring to Table 1. The photographic film on the screen is too thin, easy to produce dot deformation, surface roughness is too large, it is suggested that the minimum thickness of the photographic film should be controlled in about 8μm; When using light curing ink, the thickness of the photographic film should be thinned accordingly, 4μm.

The above points are the key technology of making the screen plate with capillary film. In addition, after the screen plate is exposed, developed and dried, if it is placed for a certain time, that is, after the exposure and development, it stays for 24 hours and then is used on the machine, which can further improve the quality stability of the screen in the use process.