Discussion on the application of Gu Kangli water-b

2022-08-13
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Discussion on the application of Gu Kangli water-based ink

I. printing faults and treatment methods of gravure ink

1 A53/a54 ink calculates the safety tightening torque value of non-metallic materials according to the safety factor of 1. The reason is: first, the viscosity of the ink is too low, which leads to poor transfer of dark parts, and even the contrast of layers tends to weaken. The second is the excessive penetration of ink due to uneven plastic or rough paper. The third is the poor reproducibility of the printed ink film due to the poor coloring power of the gel of the ink or the pigment in the ink system

treatment methods: first, the proportion of pigments in the ink system should be appropriately larger or pigments with high coloring power should be selected as colorants; second, the printing (grain) holes should be lighter during plate making. Third, increase the proportion of wetting dispersant to improve its chromogenic power. Fourth, add antifreeze organic solvents such as propylene glycol butyl ether appropriately to avoid gel and maintain the fluidity of the ink. Fifthly, non surfactant such as stearic acid should be properly added to prevent the gloss of the ink, especially the transfer performance, from being affected by the penetration of the ink after printing

2. Reasons for the appearance of fog and paste on the ink film

first, when the ink of water-based gravure (A53, a54) is printed at high speed (150 ~ 300m/min), fog or paste is produced. This is often due to the slow dryness of ink, especially the unreasonable formulation design of water-based binder and medium water or alcohol, ester organic solvent in the ink system, which leads to the dull surface of the ink film or the formation of gray fog after printing. Second, due to the poor solubility of thinner and ink, the solubility is poor after adding. There are also cases where the dry ink on the plate increases the resistance of the scraper or the paste caused by the mixing of paper powder and plastic powder on the substrate

processing methods: first, improve the accuracy (connectivity) and surface finish of the version; Second, increase the pressure of the scraper; Third, adjust the solubility of diluent and ink

3. Reasons for slow ink drying: first, the slow ink drying is often caused by the slow evaporation rate of water, usually due to the high viscosity or the deep hole of the plate, and the ink film is too thick, or due to non absorbent plastic, aluminum foil and other non absorbent ink, Second, it is caused by the low temperature of drying (including infrared magnetic wave drying power) or the condition of "large belt with small, small lead to large" (including facilities) without special stretching attachment wind or drying equipment

treatment methods: first, improve the ordinary hot blowing method, and the temperature of the hot drum type is 20 ~ 30 ℃ higher than that of the solvent type; The second is to change the electromagnetic wave frequency of high-frequency dielectric heating from 10 ~ 150MHz to the microwave heating and drying method of 300 ~ 3 wind chime "Kodama echo" 000mhz; Third, use preheating method to improve the surface temperature of paper, plastic or aluminum foil for packaging and printing; Fourth, improve the ambient temperature (especially the printing plate)

4. Poor adhesion fastness

reasons: first, the substrate is not handled well; Second, use the wrong ink; Third, the ink system contains excessive surfactants; Fourth, the printing pressure is too small; Fifth, the ink viscosity is not suitable; Sixth, the ink film remains excessive water or solvent

treatment methods: first, reprocess the substrate; The second is to change the suitable ink; Third, choose the ink that does not contain surface activity as much as possible; Fourth, improve the printing pressure; Fifth, choose ink with high resin content and low viscosity; Sixth, in the ink system or diluent formulation design, try to use the mixed solvent that forms a gradient or put the printed matter in the drying room to remove excess water

II. Treatment of relief ink printing failure

note: T37 relief is usually used for rubber manual engraving, flexo laser engraving, photosensitive resin relief, etc. Generally, the medium and low grades are used as cartons, paperboards and cartons, and the medium and high grades are used as plastic woven bags, coated paper, such as cigarette bags, wine labels, medicine bags and other substrate materials

1. Gel or roughening

reasons: first, the ink is improperly stored, expired or left; The second is to use the wrong cosolvent; Third, the ink is mixed with other inks and so on

the treatment methods are as follows: first, store in a sealed manner and add an appropriate amount of true solvent; Second, change the ink; Third, use diluent (formula) with good solubility; Fourth, pay attention to the variety of ink before adjustment

2. Unable to get the expected viscosity, viscosity

reasons: first, the ink has thixotropy; Second, the temperature is too low; Third, blistering; Fourth, the organic solvent of the ink system is volatile; Fifth, the viscosity is too low; Sixth, the ink system binder (resin) is improperly selected, lack of adhesion (bonding strength), and so on

the treatment methods are: first, stir for 5 ~ 10min before using ink; The second is to keep the ink at 25 ℃; Third, add an appropriate amount of defoamer (or prepare both external and internal defoaming); Fourth, adding really strong solvent additives; Fifth, add an appropriate amount of 8 or ammonia (amine) water; Sixth, add tackifying resin or crosslinking agent, etc

3. Reasons for ink foaming or poor flow: first, there is too little defoamer or poor defoamer; Second, the circulation of ink is insufficient; Third, the pipe leaks; Fourth, the ink is too thin; Fifth, excessive anti sedimentation thickener, etc

the treatment methods are as follows: first, increase the defoaming agent appropriately (excessive pinholes are more difficult to eliminate); Second, improve the circulation; Third, check the pipe to prevent air leakage; Fourth, constantly add new ink to prevent the ink from being too thin; Fifth, add 80.1 ~ 3% to remedy it; Sixth, increase the circulation of the pump; Seventh, add new ink so that it is not thin

4. Poor transfer to the substrate

because: first, the printing pressure is insufficient; Second, the substrate is too water-resistant; Third, the printing plate strength is too high; Fourth, the ink roller is worn and aging

treatment methods: first, improve the printing pressure; Second, use water-based ink or add coupling agent (such as 200s); Third, the hardness of plate should be 423; Fourth, replace the blocked or worn metal roller

5. Overprint (overprint poor) poor

reasons: first, in multi-color overprint, the former color is not dry, and the latter color is printed again; Second, the (ink) color of the back print causes the peeling (biting) phenomenon of the previous color; Third, the color ink sleeve (stack) of post printing cannot be printed; Fourth, the ink film is crystallized or not rewetting (the ink film is not slightly soluble)

treatment methods: first, improve the drying speed of the previous color; Second, reduce the viscosity of the latter color or reduce the printing pressure; Third, increase the viscosity of the latter color or improve the adhesion; Fourth, improve the pH value of the ink or add an appropriate amount of wetting AIDS

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