The wide applicability of flat screen printing also depends on the diversification of ink (ink). Different properties of the dye can be printed by screen printing plates, different particles of pigments, gold and silver powder, mica thins, microcapsules, etc. can also be printed by screen printing plate. A variety of printing inks (inks), their chemical properties will be different, some acidic, some alkaline, and some with oxidative, and some with reducing. The influence of colorant (ink) performance on the screen selection is mainly reflected in two aspects: one is the size of the particles in the colorant (ink), and the other is the chemical performance of the colorant (ink).

When selecting a screen, it is generally ensured that the width (opening) of the selected screen mesh is 3 times the size of the particles in the colorant (ink). The chemical properties of colorants (inks), such as strong acids and strong alkalis, can cause damage to the screens of different materials. Nylon screens are not resistant to strong acids, carbolic acid, formic acid, and cresols, while polyester screens are highly resistant to acids, but Not strong alkali.

After selecting a good screen, in order to prevent the shrinkage of the photosensitive film, sand holes, image breakage and other phenomena caused by dirt, dust, grease, etc., the photosensitive adhesive can be more firmly combined with the screen, so that the printing pattern is durable Increased sexuality requires the pretreatment of the selected screen. The pretreatment includes removal of stains on the screen and roughening of the screen. Before the plate is made, the screen must be fully cleaned. The cleaning agent is usually a neutral or slightly alkaline washing powder. A 20% aqueous caustic soda solution can also be used. The caustic soda aqueous solution has a good degreasing effect. After washing the net, clean the screen with water and wash the cleaning agent on the screen. The roughening of the screen can improve the adhesion of the screen to the photosensitive film and extend the life of the screen.

Roughening methods include chemical and physical methods. The roughening of polyester mesh can be carried out at a certain concentration of caustic soda at 100°C. The treatment time is related to the concentration of caustic soda, the concentration of caustic soda is high, and the treatment time must be shortened accordingly. Otherwise, it is prolonged. The prerequisite is that the use of polyester mesh cannot be affected. Caustic soda treatment is a chemical method, which can not only play a role in degreasing, decontamination, but also play a role in roughening. The physical method of roughening is the use of grinding paste on the surface of the wire mesh. The operation can be performed mechanically or manually. Grinding paste grinding net is mainly carried out on the printing surface of the screen, generally need to wear 5 ~ 7min.

Source: China Dyeing & Finishing Industry Information Center