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Evaporative drying type - through the solvent evaporation makes the ink film adhesion method.
Oxidative polymerization type - The method of forming ink adhesion by oxidation reaction.
Two-fluid reaction type - The method of making the ink film by two-component chemical reaction.
Ultraviolet curing type - A method of forming a film by adhesion by a chemical reaction caused by ultraviolet irradiation.
Different drying methods (the principle and application range of the air dryer) The ink can bring different gloss, different resistance (mechanical resistance, chemical resistance, weather resistance performance) to the ink film after printing, and use different drying equipment, resulting in different costs. Users need to choose carefully.
2 according to the type of ink material can also be divided into a variety of types
However, different ink manufacturers choose to use different resins, can be roughly divided into epoxy resin, polyurethane, polyester, vinyl, acrylic, rubber and so on. Only the different substrates of different materials can be used to select inks with different resin types, so as to avoid improper adhesion caused by incorrect ink selection.
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
It is mainly due to the fact that various diluents have different solvency for various types of inks in order to avoid poor printing effects.
4 Japan Co., Ltd.
Second, the use of screen printing ink, the failure and its treatment
The coating roll for dry compounding is usually cleaned with a glue tank and a circulation pump after the end of the daily work.
(Excluding 24 hours operation). It is difficult to completely remove the glue with ethyl acetate. A small amount of glue remains on the applicator roller, and it can be plugged for a long period of time. Working in the case of a plug plate, due to a decrease in the amount of glue applied, causes problems such as poor appearance (bubbling) and low peeling temperature.
In order to prevent such quality complaints from happening, we should periodically use a stripper (wash solution) to clean the applicator roller to obtain a stable coating amount.
Procedure: 11 The plastic water tank and the coating roll are washed with ethyl acetate.
21 Put 3 to 4 sheets of film in the plastic tank (OPP, PET, CPP, LLDPE, etc.).
31 While rotating the coating roller at a slow speed, a plate cleaner was applied to the surface with a paint brush, and then allowed to stand for 5 to 10 minutes.
41 Use a metal brush to brush hard on the surface of the roller 2 or 3 times.
51 Do not wash again with a brush.
61 Wash the solution with 2~3L ethyl acetate and fine copper wire brush.
71 Remove the film containing the bath solution and the ethyl acetate film in the tank.
81 Then add about 10L of ethyl acetate to the applicator roller in the tank, and slowly rotate the applicator roller while scrubbing with a metal brush and a wire cloth until it is clean.
91 Repeat 7 again.
101 Repeat steps 8 and 9 again (in order to completely remove the foreign material).
Prepare 3 to 5 L of ethyl acetate, and wipe it with a wire from the top of the coating roll.
121 Wipe the applicator roller with a clean, dry wire.
131 Remove the ethyl acetate from the tank and place the film.
141 The cleaning cycle should be based on the appearance of the product. Cleaning is usually done once a week or two weeks.
Note: 11 Washing solution SP-751 is a strong acid solution. It must be worn with rubber gloves, protective glasses and masks.
21 The ethyl acetate used in 5-11 in the operation step can still be used in the step 6-8 if it is restored to contain foreign matter.
31 wash solution has a corrosive effect on the metal. If you leave the applicator roll coated with the plate solution for more than 1 hour, the chrome plated applicator roll may peel off, and the cleaning must be completed in 1 hour.
The reason is that 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.
31 pin hole: 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 material must be pre-treated, and the leveling agent must be added or the good ink must be replaced.
51 Adhesion is poor: the reason is that the ink is not properly selected, the pre-treatment is not enough; the substrate has impurities, the drying temperature, and the time are insufficient; the amount of additives, curing agents, and driers is not appropriate, and the two-component ink is superimposed upon printing , 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-linked into a dense special ink film, the completely cured ink film is difficult to be etched by the solvent, so when the double-layered ink is printed, the background color is dry. Can print, other factors can be adjusted accordingly.
51 Drawing: The reason is that the viscosity is too high, the drying is too fast, and the ink is mixed with the wrong resin and solvent. Use an appropriate solvent, adjust the proper viscosity, or replace the good ink.
61. Migration and fading: The reason is that improper pigments are used in inks, especially if there are a large number of plasticizer soft films, and migration is more likely to occur. The appropriate ink should be used.
71 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 local water vapor to solidify in the ink film inside or on the surface causing white fogging. Therefore, an appropriate drying speed should be selected or the space humidity should be reduced, or a good ink should be replaced.
Third, additives, curing agents, driers, varnish oil use
1 Additives include defoamers, leveling agents, anti-friction agents, matting agents, etc., all of which should be properly added in accordance with the instructions for use. When not in use, poor printability, poor gloss, slow drying, and poor adhesion will result. .
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.
31 varnish is usually used for 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 ink film cover is used. After adding the varnish, a suitable proportion of thinner should be added to prevent poor printing effect.
The choice and application of silk printing member materials
1 Drying can be divided into: