Common printing failure of letterpress ink and its processing method
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The T37 type letterpress is commonly used as an eraser hand-engraved flexographic laser engraving and photosensitive resin relief. Generally used in medium and low grades as cartons, cardboards, cartons, medium and high grades used as plastic woven bags, coated paper such as cigarette packets, wine labels, medicine bags and other substrate materials.
1. Gel or hair
Reason: First, the ink is improperly stored, stored expired or leftover ink; second, the wrong solvent is used; third, the ink is mixed with other inks, and the like.
The treatment method is as follows: one is sealed storage, an appropriate amount of true solvent is added; the second is to change the ink; the third is to use a good solubility diluent (formulation); the fourth is to pay attention to the ink type before adjustment.
2. Can not get the expected viscosity, viscosity
Reasons: First, the ink is thixotropic; second, the temperature is too low; third is foaming; fourth, the organic solvent of the ink system is volatile; fifth, the viscosity is too low; and sixth, the ink system binder (resin) is improperly selected, lacking adhesion. Sex (bond strength) and so on.
The treatment method is as follows: one should be stirred for 5 to 10 minutes before using the ink; the second is to keep the ink at 25 ° C; the third is to add an appropriate amount of defoaming agent (or to prepare both the outer bubble and the inner bubble); A strong potting aid; five is to add an appropriate amount of x 8 or ammonia (amine) water; six is to add a tackifying resin or a crosslinking agent and the like.
3. Ink blistering or poor flow
Reasons: First, the defoaming agent is too little or the defoaming agent is bad; the second is that the circulation of the ink is insufficient; the third is that the tube is leaking; the fourth is that the ink is too thin; the fifth is the excess of the anti-settling thickener.
The treatment method is as follows: First, the amount of defoaming agent is increased in an appropriate amount (the pinhole is more difficult to eliminate in excess); the second is to increase the circulation amount; the third is to inspect the tube to prevent gas leakage; and the fourth is to continuously replenish the new ink without making the ink too thin; The fifth is to add ×80.1 to 3% to remedy; the sixth is to increase the circulation of the pump; the seventh is to add new ink to make it not too thin.
4. Poor transferability to the substrate
Because: first, the printing pressure is insufficient; second, the substrate is too strong in water resistance; third, the plate strength is too high; fourth, the ink roller wears and ages.
Treatment methods: one is to increase the printing pressure; the second is to use a water-retaining ink or a coupling agent (such as 200S); the third is to configure the hardness of the plate to be 42 ± 3; the fourth is to replace the blocked or worn metal reticulated enamel.
5. Overprinting (poor printing) is poor
Reason: First, in the multi-color overprinting, the first color is not dried and the color is printed again; the second is the post-printing (ink) color causes the previous color to peel off (biting) phenomenon; the third is the post-printing color ink sleeve (stack) printing The fourth is that the ink film is crystallized or has no rewet (the ink film is not slightly soluble).
Treatment method: one is to increase the drying speed of the previous color; the second is to reduce the viscosity of the latter color or reduce the printing pressure; the third is to increase the viscosity of the latter color or improve the adhesion; the fourth is to increase the pH value of the ink or add a proper amount of the dampening agent. .
6. The set (stack) can not be printed
Reasons: First, the previous one (color) drying too fast or crystallization or no resolubility; the second is the paper absorbing ink dampening or even non-absorbent plastic and the warping angle caused by the expansion and contraction.
Treatment method: First, when the pre-color is not completely dry, one (way) color or an appropriate amount of co-solvent is added to improve the PH value; the second is to master the post-color printing timing or change the paper, add appropriate amount of dilute agent or change the expansion and stability Ink.
7. Imprinting is not allowed
Reasons: First, the tension of the substrate is not uniform; second, the bearing at both ends of the plate is worn or the plate roller is not clear; the third is that the substrate has a ruffle; the fourth is that the printing of the previous color is too large, so that The pattern is deformed; the fifth is that the substrate joint is not flat or the thickness of the two sides is different; the sixth is that the printing plate is swollen by the ink and protrudes and deforms. Treatment method: First, adjust the tension of the retracting material (substrate); second, check or replace the worn or deformed plate; third, adjust the tension or replace the substrate; fourth, adjust the printing pressure; fifth, re-join; sixth, replace New plate.
8. Color instability
The reasons are: first, there is a change in viscosity and pH; second, there is a deviation in the ink dispensing process or the printing operation procedure.
The treatment method is as follows: one is to re-adjust the viscosity or control the pH adjusting agent; the other is to check the ink dispensing process and the operation process.
9. The color is too light
Reason: First, the viscosity is too low; second, the anilox roller mesh is too thin; third, the anilox roller is worn or not cleaned; fourth, the amount of ink is too small.
The treatment method is as follows: one is to increase the viscosity of the ink; the other is to change the anilox roller of the coarse mesh; the third is to replace the anilox roller or thoroughly clean the anilox roller; the fourth is to speed up the printing speed or reduce the pressure of the ink transfer roller.
10. The color is too dark
Reason: First, the viscosity of the ink is too high or the color developing power is too strong; second, the anilox roll is too rough; third, the amount of ink is too large or the ink system ink additive or filler is excessive.
Treatment method: one is to add a thinner to reduce the viscosity of the ink; the other is to add a lightening agent to reduce the depth of the ink; the third is to increase the pressure of the transfer roller or reduce the ink additive in the ink system.
11. Uneven ink
Reasons: First, the printing plate is not flat; second, the thickness of the substrate is not uniform; third, the number of netting rolls is too low; and fourth, the anilox roll has dry or residual ink.
Treatment methods: one is to grind the back of the printing plate or the sticker is corrected; the second is to change the substrate with uniform thickness; the third is to replace the anilox roller with high number of wires. The fourth is to clean the ink residue remaining in the mesh of the anilox roller.
12. Ink film adhesion is poor
Reasons: First, the ink quality is poor or the wrong ink is used; second, the substrate does not meet the processing requirements; third, the wrong diluent is used, the printing pressure is too small or the ink layer is too thick; fourth, the tinting strength of the ink is too low.
Treatment methods: first, change the adapted ink; second, control the processing of the substrate; third, replace the corresponding thinner; fourth, increase the printing pressure or select the ink with good tinting strength or reduce the ink supply.
13. Ink gloss is poor
Reason: First, the quality of the ink is not good or has a certain permeability; second, the substrate is too rough and the viscosity is too low (usually the viscosity should be: 40 to 60, while the gravure is 18 to 25 S/25 ° C. cup).
Treatment method: First, change the quality of the ink (especially the ink system is consistent in the dry table); second, change the substrate on the surface of the substrate or impermeable substrate (or change the ink that does not penetrate the paper); the third is to control the ink Viscosity 35 ~ 60S / 25 ° C · 4 cups. Fourth, the rosin-modified ink with high pH value or high-molecular-weight acrylic resin ink or coupling agent is used to remedy the problem.
14. Ink printing fades
Reasons: First, the filler in the ink is color-retained or pigments of different wavelengths are used; second, the pigment has poor alkali resistance and heat resistance.
Treatment methods: First, replace the non-color-retaining calcium filler or choose pigments with similar color wavelengths; second, choose alkali-resistant and heat-resistant pigments; third, switch to light-resistant pigments or add appropriate amount of UV-resistant absorbent or add anti-drug The oxidant is 0.1 to 1.0%.
15. The picture is blurred, imaginary, raw
Reasons: First, the printing quality is poor; second, the printing plate is too tightly contacted with the ink roller; third, the viscosity of the ink is too large or the ink is thick; the fourth is that the dry speed of the ink is too fast; and the fifth is the influence of environmental dust.
Treatment method: First, the pad should be flat and uniform; second, adjust the pressure between the printing plate and the ink roller; third, adjust the viscosity of the ink, mix with water, alcohol (or ester) or reasonably stir the ink or increase the coupling agent The ratio is four; the fourth is to reduce the drying speed, and the fifth is to control the environmental dust.
16. Graphic crush
Reason: First, the printing plate is too soft or the pad is too elastic; the second is too tight contact or the printing pressure is too high; the third is that the viscosity of the ink is too low.
Treatment method: First, the pad should be suitable, or adjust the height of the plate; second, adjust the printing pressure or plate, the amount of the roller is loose; third, replace the ink with high viscosity and hardness or stir the ink in an appropriate amount.
17. Ink film pinhole
Reasons: First, the ink is diluted excessively; second, the internal defoaming aid is insufficient; third, the ink viscosity is too low, and the ink is excessive.
Treatment method: First, add the original amount of ink in the ink; second, control the amount of defoaming agent inside and outside; third, add the amount of original ink and mix well.
18. Printing wear
Reasons: First, the printing is too heavy; second, the contact is too tight; third, the printing plate is of poor quality; fourth, the ink or thinner corrodes the printing plate.
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. Printed spots have spots
Reason: First, the ink is too thin; second, the surface of the substrate is not uniform; third, the viscosity of the ink is too small; fourth, the printing plate is uneven.
Treatment method: one is to add coupling agent 200S or original ink; the second is to use micro-elastic ink or thick and uniform printing material; third is to choose ink with high viscosity or high viscosity; fourth is to adjust or check the inking system .
20. The ink is drying too fast
Reason: 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 large; the drying temperature is too high.
Treatment methods: first, increase the printing speed; second, increase the thinner; third, add slow-drying diluted true solvent; fourth, reduce the drying temperature or eliminate the drying system facilities.
21. Printed copies
Reasons: First, the ink is too thin; second, the substrate is too rough; third, the ink is too dry; fourth, there is a spherical pigment or an excessive amount of surfactant in the ink system.
Treatment methods: one is to add the original ink; the other is to replace the substrate with the flat surface; the third is to change the fast drying ink; the fourth is to use the pigment that is not spherical or to control the amount of surfactant.
22. Blocking, paste
Reasons: First, the printing plate is too shallow; second, the printing pressure is too heavy; third, the ink supply is too much; fourth, the ink viscosity is too high; and fifth, the ink drying speed is too fast.
Treatment methods: First, use the deep version; second, adjust the printing pressure; third, reduce the ink supply; fourth, dilute the ink; fifth, lower the drying temperature or add a slow drying agent or increase the printing speed appropriately. 23. Sticky pages, dirty
Reasons: First, the ink film is too slow after printing; secondly, the tension of the rewinding paper or plastic is too loose; the third is that the product is piled up and heated; the fourth is that the resin system softening point is too low; the fourth is the plastic back surface of the substrate that is mishandled. .
Treatment method: First, switch to dry fast ink or increase the drying (or downwind) temperature, secondly, increase the evaporation solvent or add catalyst; thirdly, reduce the rewinding tension; fourth, it should be tested before printing. Substrate.
24. Ink film drying is too slow
Reasons: First, the printing speed is too fast; second, the ink (system) is too slow to dry; third, the drying temperature is low.
Treatment methods: one is to reduce the speed of the printing machine; the second is to add a thinner or driers that evaporate quickly; the third is to increase the ambient temperature or raise the temperature or increase the blowing.