Because the screen printing process has a wide range of applications and low investment, substrates that are difficult to print for other printing methods use screen printing. Therefore, the screen technology has been rapidly developed in recent decades. Bringing the screen printing process to such fine features is that in addition to diversified printing equipment, there is also a versatile, multi-purpose screen printing ink. Therefore, it is more important to choose and use silk screen printing inks than to select other printing methods (gravure, relief, lithography, flexo).
First, the choice and use of screen printing ink Silk printing ink and other types of ink are the same with the pigment, resin, solvent, additives made by grinding.
1. Drying can be divided into:
Steam drying type - the method of making the ink film by solvent volatilization.
Oxidative Polymerization - A method of forming an ink by means of an oxidation reaction.
Two-fluid reaction type - The method of forming ink adhesion by two-component chemical reaction.
Ultraviolet curing type - a method of forming a film by adhesion of a chemical reaction caused by ultraviolet irradiation.
Different drying inks can bring different gloss, different resistance (mechanical resistance, chemical resistance, and weather resistance) to ink film after printing. Different drying equipments produce different costs, so users need to choose carefully.
2. According to the ink connecting material type can also be divided into many types, but different ink manufacturers choose different resins, can be roughly divided into epoxy resin, polyurethane, polyester, vinyl, acrylic, rubber and many more. Only with a clear definition of the substrate and different materials, inks of different resin types can be used to avoid the poor adhesion due to ink errors. For substrates with unclear materials, it is best to determine the selected ink after the printing test.
3. Different types of inks use the thinners provided by their manufacturers, mainly because various diluents have different solvency for different types of inks to avoid poor printing effects.
Second, the use of screen printing ink, the failure and its treatment 1. Foaming: The reason is that the printing viscosity is too high, too fast drying, version and the substrate has been separated from too fast, bad layout, the ink itself has a problem and other factors , can take appropriate measures to adjust, or add appropriate defoamer and replace the ink.
2. Blocked version: 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 diluent, the printing plate surface by the wind, the ink fineness is not qualified or caused by impurities. Should adjust the drying speed properly, or replace the ink.
3. Pinhole: The reason is that the printed body is too smooth, the printing surface has a grease protection layer or impurities, and the ink itself is not good. Therefore, the surface of the printed object must be pretreated, and the leveling agent must be added or the good ink must be replaced.
4. Adhesion is poor: the reason is that the ink is not properly selected, the pre-treatment is not sufficient; the substrate has impurities, and the drying temperature is insufficient; the amount of additives, curing agents, and driers is not appropriate, and the two-component ink is printed in overlap color , due to solid color and other factors. Because the polarity of materials such as PE, PP, PET, and aluminum foil is extremely low or too smooth, electric sparks, flames, and acid immersion are generally performed to increase the surface tension of the printed surface. After the ink film of the two-component ink is cured, due to a chemical reaction, cross-linking becomes a dense and strong ink film, and the completely cured ink film is difficult to be eroded by the solvent, so when the double-layered ink is printed, the background color is dried. Can print, other factors can be adjusted accordingly.
5. Drawing: The reason is that the viscosity is too high, the drying is too fast, and the ink is mixed with the improper use of the resin and the solvent. The proper solvent should be used to adjust the proper viscosity or replace the good ink.
6. Migration, fading: The reason is the improper use of ink in the ink, especially a large number of plasticizer soft film, more prone to migration, should use the appropriate ink.
7. White or printed surface is misty: The reason is that thinner contains moisture, the printing environment has high humidity, or the printing ink itself is poor. Since the printing surface is dry, the solvent volatilizes to absorb the surrounding heat, causing the partial water vapor to solidify in the ink film or the surface to cause white fogging. Therefore, the proper drying speed should be selected or the space humidity should be reduced, or the good ink should be replaced. Third, additives, curing agents, driers, varnish oil use 1. Additives, including defoamers, leveling agents, friction agents, matting agents, etc., should be added according to the instructions for use, improper, will cause printing Poor results such as poor sex, poor gloss, slow drying, and reduced adhesion.
2. The curing agent and driers should be accurately added according to the proportion of use, otherwise it will increase the crust of the ink, resulting in poor adhesion.
3. Varnish is usually used in the production of gold and silver inks. The transparency of the ink film is increased, the gloss of the ink film is increased, and the function of the ink film cover is added. After adding the varnish, an appropriate proportion of thinner should be added to prevent poor printing effect. (Jiong Rong Co., Ltd., Department of Technical Research, Jianbao)
Picked from Hunan Packaging 2000/1
First, the choice and use of screen printing ink Silk printing ink and other types of ink are the same with the pigment, resin, solvent, additives made by grinding.
1. Drying can be divided into:
Steam drying type - the method of making the ink film by solvent volatilization.
Oxidative Polymerization - A method of forming an ink by means of an oxidation reaction.
Two-fluid reaction type - The method of forming ink adhesion by two-component chemical reaction.
Ultraviolet curing type - a method of forming a film by adhesion of a chemical reaction caused by ultraviolet irradiation.
Different drying inks can bring different gloss, different resistance (mechanical resistance, chemical resistance, and weather resistance) to ink film after printing. Different drying equipments produce different costs, so users need to choose carefully.
2. According to the ink connecting material type can also be divided into many types, but different ink manufacturers choose different resins, can be roughly divided into epoxy resin, polyurethane, polyester, vinyl, acrylic, rubber and many more. Only with a clear definition of the substrate and different materials, inks of different resin types can be used to avoid the poor adhesion due to ink errors. For substrates with unclear materials, it is best to determine the selected ink after the printing test.
3. Different types of inks use the thinners provided by their manufacturers, mainly because various diluents have different solvency for different types of inks to avoid poor printing effects.
Second, the use of screen printing ink, the failure and its treatment 1. Foaming: The reason is that the printing viscosity is too high, too fast drying, version and the substrate has been separated from too fast, bad layout, the ink itself has a problem and other factors , can take appropriate measures to adjust, or add appropriate defoamer and replace the ink.
2. Blocked version: 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 diluent, the printing plate surface by the wind, the ink fineness is not qualified or caused by impurities. Should adjust the drying speed properly, or replace the ink.
3. Pinhole: The reason is that the printed body is too smooth, the printing surface has a grease protection layer or impurities, and the ink itself is not good. Therefore, the surface of the printed object must be pretreated, and the leveling agent must be added or the good ink must be replaced.
4. Adhesion is poor: the reason is that the ink is not properly selected, the pre-treatment is not sufficient; the substrate has impurities, and the drying temperature is insufficient; the amount of additives, curing agents, and driers is not appropriate, and the two-component ink is printed in overlap color , due to solid color and other factors. Because the polarity of materials such as PE, PP, PET, and aluminum foil is extremely low or too smooth, electric sparks, flames, and acid immersion are generally performed to increase the surface tension of the printed surface. After the ink film of the two-component ink is cured, due to a chemical reaction, cross-linking becomes a dense and strong ink film, and the completely cured ink film is difficult to be eroded by the solvent, so when the double-layered ink is printed, the background color is dried. Can print, other factors can be adjusted accordingly.
5. Drawing: The reason is that the viscosity is too high, the drying is too fast, and the ink is mixed with the improper use of the resin and the solvent. The proper solvent should be used to adjust the proper viscosity or replace the good ink.
6. Migration, fading: The reason is the improper use of ink in the ink, especially a large number of plasticizer soft film, more prone to migration, should use the appropriate ink.
7. White or printed surface is misty: The reason is that thinner contains moisture, the printing environment has high humidity, or the printing ink itself is poor. Since the printing surface is dry, the solvent volatilizes to absorb the surrounding heat, causing the partial water vapor to solidify in the ink film or the surface to cause white fogging. Therefore, the proper drying speed should be selected or the space humidity should be reduced, or the good ink should be replaced. Third, additives, curing agents, driers, varnish oil use 1. Additives, including defoamers, leveling agents, friction agents, matting agents, etc., should be added according to the instructions for use, improper, will cause printing Poor results such as poor sex, poor gloss, slow drying, and reduced adhesion.
2. The curing agent and driers should be accurately added according to the proportion of use, otherwise it will increase the crust of the ink, resulting in poor adhesion.
3. Varnish is usually used in the production of gold and silver inks. The transparency of the ink film is increased, the gloss of the ink film is increased, and the function of the ink film cover is added. After adding the varnish, an appropriate proportion of thinner should be added to prevent poor printing effect. (Jiong Rong Co., Ltd., Department of Technical Research, Jianbao)
Picked from Hunan Packaging 2000/1