The indispensable drying equipment in the most pop

The indispensable drying equipment in printing

because the silk printing process is widely used, the investment is small, and the substrate that is difficult to be printed by other printing methods uses silk printing to inspect the degree of grain length, so the silk process has developed rapidly in recent ten years. The excellent feature of silk printing process is that in addition to diversified printing equipment, there are multi-functional and multi-purpose silk printing inks. Therefore, it is more important to choose and use silk screen printing ink correctly than to choose other printing methods (intaglio, relief, lithography, flexo)

I. selection and use of silk screen printing inks

silk screen printing inks, like other types of inks, are mixed and ground with pigments, resins, solvents and additives

1. According to the drying method, it can be divided into:

steam drying method, which makes the ink film-forming and adhesion through solvent volatilization

oxidation polymerization method of making ink film-forming and adhesion through oxidation reaction

two liquid reaction method to make ink film-forming and adhesion through two-component chemical reaction

UV curing chemical anti HRB introduced by UV irradiation should make the ink film-forming adhesion method

different drying methods of inks can bring different gloss and different resistance (mechanical resistance, chemical resistance and climate resistance) to the ink film after printing. Different drying equipment will produce different costs, so users need to choose carefully

2. According to the type of ink binder, it can also be divided into many types, but different ink manufacturers choose different resins, which can be roughly divided into epoxy resin, polyurethane, polyester, vinyl, acrylic acid, rubber and so on. Only by specifying the different materials of the substrate, different resin types of inks can be selected to avoid the adverse consequences of adhesion caused by ink errors. For the substrate with unclear material, it is best to determine the selected ink after passing the printing test

3. Different types of inks use the supporting diluents provided by their manufacturers, mainly because various diluents have different solubility for different resin types of inks, so as to avoid adverse printing effects

II. Faults and their solutions during the use of silk screen printing ink

1 Foaming: the reason is that the printing viscosity is too high, the drying is too fast, the plate is separated from the substrate too quickly, the layout is poor, the ink itself has problems and other factors. Corresponding measures can be taken to adjust, or add an appropriate amount of defoamer and replace the ink

2. Blocking: the reason is that the drying is too fast, the printing speed is too slow, the printing viscosity is too high, the use of poor and improper diluents, the printing plate is blown by the wind, the ink fineness is unqualified or there are impurities. The drying speed should be adjusted appropriately, or the ink should be replaced

3. Pinhole: the reason is that the printed body is too smooth, the printing surface has a grease protective layer or contains impurities, and the ink itself is poor. Therefore, the surface of the printed object must be pretreated, leveling agent added or excellent ink replaced

4. Poor adhesion: the reason is that the ink is not properly selected and the pretreatment is not sufficient; The substrate has sundries, and the drying temperature and time are insufficient; The improper dosage of additives, curing agents and driers, and the hardening of the background color during the two-component ink overlay printing. Because the chemical polarity of PE, PP, pet, aluminum foil and other materials is quite low or too smooth, they are generally treated with spark, flame, strong acid immersion and other treatments to improve the surface tension of the printing surface. After the ink film of the two-component ink is cured, due to the chemical reaction, it is crosslinked into a dense and strong ink film, and the fully cured ink film is difficult to be etched by the solvent. Therefore, when printing with superimposed colors, the bottom color can be printed after the surface is dry, and other factors can be adjusted with corresponding methods

5. Wire drawing: the reason is that the viscosity is too high, the drying is too fast, and the resin used in the ink is not properly matched with the solvent. You should use the appropriate solvent, adjust the appropriate viscosity, or replace the excellent ink

6. Migration and fading: the reason is that improper pigments are used in the ink, especially with a large amount of plasticizer soft film, which is more prone to migration. Appropriate ink should be selected

7. Whitening or foggy printing surface: the reason is that the diluent contains water, the air humidity in the printing environment is high, or the printing ink itself is poor. When the printing surface is dry, the solvent volatilization will absorb the surrounding heat, causing local water vapor to solidify in the ink film or cause white atomization on the surface, so you should choose an appropriate drying speed or reduce the space humidity, or replace youl ink

III. use of additives, curing agents, driers, and inking oils

1. Additives include defoaming agent, leveling agent, anti friction agent, matting agent, etc., which should be added appropriately according to the instructions. If not, it will cause poor printability, poor gloss, too slow drying, decreased adhesion and other adverse consequences

2. Curing agent and drying agent should be added accurately according to the use proportion, otherwise it will increase the ink scaling and produce poor adhesion

3. Inking oil is usually used in the production of gold and silver ink. The transparency of the ink film is increased, the gloss of the ink film is improved, and the ink film cover is used. After adding inking oil, appropriate proportion of diluent should be added to prevent adverse printing effect