Letterpress ink common printing failure and its processing method

T37 letterpress is usually used as a rubber hand-engraved flexographic laser engraving and photosensitive resin letterpress and so on. General medium and low grades are used for cartons, cardboards and cartons, and medium and high grades are used for plastic woven bags, coated papers such as cigarette packs, wine labels, and drug packs.

Gel or nap

Reasons: First, the ink is stored improperly, storage expired or leftover ink; second, wrong cosolvent is used; third, the ink is mixed with other inks and so on.

Treatment methods are: First, sealed storage, adding proper amount of solvent; Second, replace the ink; Third, the use of good solubility thinner (formula); Fourth, pay attention to the type of ink before adjustment.

2. Unable to obtain the expected viscosity and viscosity

Reasons: First, the ink has thixotropy; second, the temperature is too low; third, foaming; fourth, the organic solvent of the ink system is volatile; fifth, the viscosity is too low; six, the ink system material (resin) is improperly selected, and lacks adhesion. Sex (bond strength) and so on.

Treatment method is: First, use ink before stirring for 5 ~ 10min reuse; Second, to maintain the ink at 25 °C is appropriate; Third, add the right amount of defoamer (or formulate both eliminate external foam and eliminate internal bubbles); Fourth is to join True strong auxiliaries; 5 is to add an appropriate amount of × 8 or ammonia (amine) water; 6 is to add tackifier resin or cross-linking agent and so on.

3. Ink blistering or poor flow

Reasons: First, too little defoamer or defoamer bad; Second, the lack of circulation of ink; Third, the pipe leak; Fourth, the ink is too thin; Fifth, anti-sinking thickener overdose.

Treatment methods are: First, increase the amount of antifoaming agent (excessive and more difficult to eliminate pinholes); Second, increase the circulation; Third, check the pipe to prevent leakage; Fourth, constantly adding new ink does not make the ink too thin; Five is to add × 80.1 ~ 3% remedy; six is ​​to increase the circulation of the pump; seven is to add new ink to make it not too thin.

4. Poor transferability to substrates

Because it is: First, the lack of printing pressure; Second, the substrate is too strong water resistance; Third, the intensity of the printing plate is too high; Fourth, the aging of the ink roller wear.

Treatment methods: First, increase the printing pressure; Second, the use of water-reducing ink or add a coupling agent (such as 200s); Third, configure the plate hardness to 42 ± 3 is appropriate; Fourth, replace the metal anilox roller or wear.

5. Overprint (poor overprint) difference

Reasons: First, multi-color overprinting, the former color is not dry after a color and India; second is the post-printing (ink) color to make the former color peeling (biting color) phenomenon; third is the post-print color ink sets (stack) India No, the fourth is that the ink film is crystallized or has no rewetting property (the ink film is not slightly soluble).

Treatment methods: First, to improve the former color drying speed; the second is to reduce the viscosity of the latter color or reduce the printing pressure; third is to increase the viscosity of the latter color or improve adhesion; Fourth, increase the ph value of the ink or the appropriate amount of wetting additives .

6 sets (stack) not printed

Reasons: First, the previous (color) drying is too fast or crystallized or no re-dissolve; second, the paper is ink-absorbing and even non-absorbing plastic and the elasticity caused by warping.

Treatment methods: First, when the pre-color is not completely dry, one (channel) color or appropriate amount of co-solvent is added to increase the ph value after printing; secondly, the timing of color printing or paper change is appropriate, and appropriate amount of diluting agent or telescopic and stable is added. Ink.

7. Overprinting is not allowed

Reasons: First, rewinding (material) sheet material tension is not uniform; second, a certain bearing at both ends of the plate wear or plate roller does not pass; third, the substrate has a lotus leaf; four is the former color printing pressure is too large, so that Pattern distortion; Fifth, the substrate joints are not flat or have different thicknesses on both sides; Sixth, the printing plate is swollen and convexly deformed by the ink. Treatment methods: First, adjust the receiving and discharging material (substance) elasticity; second, check or replace the wear or deformation roller; third, adjust the tension or change the substrate; fourth, adjust the press pressure; New printing plate.

8. Color instability

The reasons are: First, there is a change in viscosity and pH; second, there is a deviation in the ink distribution process or the printing operation procedure.

Treatment methods are: First, re-adjust the viscosity or control pH regulator; Second, check the ink distribution process and operation process.

9. The color is too shallow

Reasons: First, the viscosity is too low; Second, the anilox roller is too thin; Third, the anilox roller is worn or not clean; Fourth, the amount of ink is too little.

Treatment methods are: First, to increase the viscosity of the ink; Second, replace the coarse mesh anilox roller; Third, change the new anilox roller or thoroughly clean the anilox roller; Fourth, to speed up the printing speed or reduce the pressure of the roller.

10. The color is too dark

Reasons: First, the ink viscosity is too high or too strong hair color; Second, the anilox roller is too rough; Third, too much ink or ink system ink additives or filler too much.

Treatment methods: First, add thinner to reduce the viscosity of the ink; second, add and remove agent to reduce the depth of ink; third, increase the pressure of the ink transfer roller or reduce the ink additives in the ink system.

11. Ink unevenness

Reasons: First, the printing plate is uneven; second, the thickness of the substrate is not uniform; third, the number of anilox roller lines is too low; and fourth, the anilox roller holes have dry or residual ink.

Treatment methods: First, grinding plate back or sticker correction; Second, change the uniform thickness of the substrate; third is to replace the network with a high number of anilox roller. The fourth is to clean the residue of the ink residue on the anilox roller network.

12. poor adhesion of ink film

Reasons: First, poor ink quality or wrong ink; Second, the substrate does not meet the requirements; Third, the wrong diluent, printing pressure is too small or too thick ink layer; Fourth, the coloring power of the ink is too low.

Treatment methods: First, the exchange of adapted ink; Second, control the handling of substrates; Third, change the corresponding diluent; Fourth, increase the printing pressure or choose a good coloring ink or reduce the ink supply.

13. Ink gloss difference

Reasons: First, the quality of the ink is poor or there is a certain degree of permeability; Second, the substrate is too rough, the viscosity is too low (usually the viscosity should be: 40 to 60, while the gravure is 18 ~ 25s/25 °C · coating 4 cup).

Treatment methods: First, replace the good quality ink (especially the ink system dry consistency in the table); second is to replace the surface of the substrate or impervious substrate impervious (or replace the ink does not penetrate the paper); third is to control the ink Viscosity 35～60s/25°C·Coating 4 cups. The fourth is to add rosin modified ink with high ph value or add high molecular weight acrylic resin ink or coupling agent to remedy it.

14. Ink press fade

Reasons: First, the filler in the ink color or use different wavelengths of pigment; Second, the pigment alkali heat resistance is poor.

Treatment methods: First, replace the non-colored calcium filler or choose a pigment with a similar wavelength; Second, select alkali-resistant, heat-resistant pigments; Third, switch to light-resistant pigments or add an appropriate amount of anti-UV absorbers or add anti-resistance Oxidizer 0.1 to 1.0%.

15. The graphic is vague, hair is imaginary, burrs

Reasons: First, the printing quality is poor; second, the printing plate is in tight contact with the ink roller; third, the viscosity of the ink is too high or the ink is thick; the fourth is the fast dryness of the ink film forming film; and the fifth is the effect of environmental dust.

Treatment methods: First, the plate should be flat and consistent; the second is to adjust the pressure between the printing plate and the ink roller; third is to adjust the ink viscosity, mixed with water, alcohol (or ester) or a reasonable stirring ink or appropriate amount of coupling agent The fourth is to reduce the drying speed, and the fifth is to control environmental dust.

16. Photo crushing

Reasons: First, the printing plate is too soft or the elasticity of the pad is too large; second, the contact is too tight or the printing pressure is too high; third, the viscosity of the ink is too low.

Treatment methods: First, the pad to be appropriate, or adjust the height of the plate; the second is to adjust the printing pressure or printing plate, the amount of roller loose; third is to use high viscosity, high hardness ink or the amount of stirring the ink.

17. Ink film pinhole

Reasons: First, the ink diluted excessive; Second, lack of defoaming agent; Third, the ink viscosity is too low, ink too much.

Treatment methods: First, the amount of ink added to the original ink; Second, control the amount of defoamers inside and outside; Third, the amount of raw ink added to stir.

18. Printing plate wear

Reasons: First, the printing is too heavy; second, the contact is too tight; third, the quality of the printing plate is poor; fourth, the printing plate is etched by ink or thinner.

Treatment methods: First, adjust the printing pressure; second, adjust the contact; third, replace the new version; fourth, replace the ink or thinner that does not corrode the printing plate.

19. The printed product has spots

Reasons: First, the ink is too thin; Second, the surface of the substrate is not flat; Third, the viscosity of the ink is too small; Fourth, the printing plate is not uniform.

Treatment method: First, add coupling agent 200s or original ink; second, use micro-elastic ink or thick and thin uniform printing materials; third, use highly viscous or high viscosity ink; fourth, adjust or check ink system .

20. Printing ink drying too fast

Reasons: First, the printing speed is too slow; second, the opening time is too long, the ink drying speed is too fast; the ink viscosity is too high; the drying temperature is too high.

Treatment methods: First, increase the printing speed; Second, increase the diluent; Third, add the slow-drying dilution of the real solvent; Fourth, reduce the drying temperature or eliminate drying system facilities.

21. Prints through the printing

Reasons: First, the ink is too thin; Second, the substrate is too rough; Third, the ink is too slow to dry; Fourth, there is an excessive amount of spherical pigments or surfactants in the ink system.

Treatment methods: First, add the original ink; second, replace the surface of the substrate on the substrate; third is to replace the fast drying ink; Fourth, the choice of non-spherical pigments or control the amount of surfactant.

22. Blocked version, paste version

Reasons: First, the printing plate is too shallow; second, the pressure of printing is too heavy; third, the ink supply is excessive; fourth, the viscosity of the ink is too high; and fifth, the ink drying speed is too fast.

Processing methods: First, select the deep version; second, adjust the printing pressure; third, reduce the ink supply; fourth, dilute the ink; 5. reduce the drying temperature or add a slow drying agent or appropriately increase the printing speed.

23. Sticky, dirty

Reasons: First, the ink film is too slow after printing; Second, the rewinding paper or plastic tension is too loose; Third, the product is stacked and heated; Fourth, the ink softening point of the ink system is too low; Fourth, the back of the plastic mishandling the substrate .

Treatment methods: First, change the fast drying ink or increase the drying (or downwind) temperature, the second is to increase the fast evaporation of the diluted solvent or add the catalyst; third is to reduce the rewind tension; four is the prepress should be detected Substrate.

24. Ink film drying is too slow

Reasons: First, the printing speed is too fast; second, the ink (system) dries too slowly; third, the drying temperature is low.

Treatment methods: First, reduce the speed of the printer; second, add a quick-evaporating diluent or driers; third, increase the ambient temperature or increase the temperature or increase the air blow.