With the packaging industry 's emphasis on environmental protection, alcohol-based inks have received increasing attention and use. In order to make better use of the performance of alcohol inks, the following briefly introduces some experiences and troubleshooting techniques in the use of alcohol inks.
I. Precautions for the use of alcohol-based inks 1. The alcohol-based inks should be stored at a temperature of 5 ~ 30 ° C, and its shelf life is one year.
2. In order to keep the product characteristics unchanged, avoid low temperature freezing or high temperature exposure.
3. Stir well before use. The remaining ink should be sealed and sealed after use.
4. In the process of printing with alcohol-based inks, if the downtime is required for a long time, the printing rollers and printing (screen) plates should be cleaned in time to avoid the volatilization of ammonia (amine) in the ink system after startup, which may cause gels or inks. Drying in the net (texture) points, which affects the print quality.
5. The ink can be adjusted according to the machine speed and the type of substrate, or diluted according to the formula of the operator, especially the ambient temperature and the conditions of the drying facilities (such as the high-frequency dielectric heating of the electromagnetic wave frequency of 10 ~ 150MHz is not ideal, you can use 300 ~ 30,000MHz microwave heating and drying method).
Second, alcoholic ink inspection method:
The test method for alcoholic inks refers to the pH test, GB / T13217.1 (color test), GB / T13217.3 (fineness test), GB / T13217.4 (viscosity test), GB / T13217 .7 (examination of adhesion fastness), GB / T13217.5 (examination of initial dryness), GB / T13217.6 (examination of tinting strength), etc.
Third, troubleshooting methods (1), poor ink reproducibility Ink viscosity is too low, resulting in poor transfer of dark tone parts, and even the contrast of the layer tends to weaken. There are also excessive penetration of ink due to uneven plastic or rough paper, and poor reproducibility of printing ink film due to poor gelation of the ink or pigment in the ink system.
Treatment methods: First, the proportion of pigments in the ink system is appropriately large or pigments with high tinting strength are selected as colorants; second, the printed (reticulated) meshes are lighter during plate making. The third is to increase the proportion of wetting and dispersing agents to improve their color development. Fourthly, an antifreeze organic solvent such as propylene glycol butyl ether is appropriately added to avoid gelation and maintain the fluidity of the ink. Fifth, it is appropriate to add non-surfactants such as stearic acid to prevent the ink's gloss, especially transfer performance, from penetrating after printing.
(2) Fog and paste on the ink film When water-based gravure ink is printed at high speed (150 ~ 300m / min), it will produce fog or paste. This is often due to the slow drying of the ink, especially the formula design of the water-based binder and the water or alcohol or ester organic solvent in the ink system is unreasonable, resulting in matte or fog on the ink film surface after printing. shape. There is also the poor solubility of thin materials and inks, which leads to poor solubility after addition. There are also dry inks on the plate that increase the resistance of the scraper or paper powder on the substrate and plastic powder mixed in.
The processing methods are: 1. Improve the accuracy of the plate (throughness) and surface finish; 2. Increase the doctor blade pressure; 3. Adjust the solubility of the thinner and ink.
(3) The reason for the slow drying of the ink is that the slow drying of the ink is often caused by the slow evaporation rate of water. Usually, the ink film is too thick due to too high viscosity or deep plate holes or non-absorbable due to non-absorbent plastics and aluminum foil. It is caused by the ink, and it is also caused by the conditions of completely no wind or no drying equipment (including facilities) or low temperature of drying (including infrared magnetic wave drying power) and so on.
The treatment methods are: 1. Improve the ordinary hot air blowing method, the temperature of the hot roller type is 20 ℃ ~ 30 ℃ higher than that of the solvent type; 2. Change the electromagnetic wave frequency from 10 ~ 150MHz to 300 ~ 3000MHz Microwave heating and drying methods; 3. using preheating to increase the surface temperature of the paper or plastic or aluminum foil used for packaging printing ; 4. increasing the ambient temperature (especially the printing plate).
(4) The reasons for poor adhesion fastness are: first, the substrate is not treated well; second, the wrong ink is used; third, the ink system contains excessive surfactant; fourth, the printing pressure is too small; fifth, the ink viscosity is not suitable; six Excessive moisture or solvent remaining on the ink film.
The processing methods are: 1. reprocess the substrate; 2. exchange suitable inks; 3. choose inks without surface activity as much as possible; 4. increase printing pressure; 5 choose inks with high resin content and low viscosity; 6 In the ink system or thinner formula design, it is possible to use a mixed solvent that forms a gradient or cut the printed products in the drying room to eliminate excess water.
Fourth, the treatment of letterpress ink printing faults Letterpress is usually rubber hand-engraved flexographic printing, laser engraving and photosensitive resin letterpress. Generally low and medium grades are cardboard, cardboard, carton, medium and high grades are plastic woven bags, coated paper such as cigarette packages, wine labels, medicine packages and other printing materials.
1. Gel or brushing The reasons are: one is that the ink is stored improperly, expired or leftover; the other is that the wrong solvent is used; the third is that the ink is mixed with other inks and so on.
The processing methods are: first, sealed storage, adding a proper amount of a real solvent; second, changing the ink; third, using a good diluent (recipe); fourth, pay attention to the type of ink before adjusting.
2. The expected viscosity and stickiness are not obtained. The reasons are: first, the ink is thixotropic; the second is the temperature is too low; the third is foaming; the fourth is the organic solvent of the ink system is volatile, the fifth is the viscosity is too low; the sixth is the ink The system binder (resin) was selected improperly and lacked cohesiveness (bond strength).
The treatment methods are: one is to stir for 5 to 10 minutes before using the ink; the other is to keep the ink at 25 ° C; the third is to add an appropriate amount of defoaming agent (or formulate both external and internal foam); and four is to add True strong-solubility assistant; Fifth, adding an appropriate amount of × 8 or ammonia (amine) water; Sixth, adding tackifier resin or cross-linking agent, etc.
3. Ink foaming or poor flow is caused by too little defoaming agent or poor defoaming agent; the second is insufficient circulation of the ink; the third is the leakage of the tube; the fourth is the ink is too thin; the fifth is the anti-settling thickener Overdose etc.
The treatment methods are: firstly, increase the amount of defoamer (excessive pinholes are more difficult to eliminate); secondly, increase the circulation; thirdly, check the tube to prevent air leakage; fourthly, continuously replenish new inks to not make the ink too thin; The fifth is to add × 8 0.1 ~ 3% to remedy it; 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 substrates. The reasons are: 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.
The processing methods are: first, increase the printing pressure; second, use a hydrophobic ink or add a coupling agent (such as 200S); third, it is appropriate to configure the plate hardness to 42 ± 3; fourth, replace the blocked or worn metal anilox roller .
5. The reason for poor overprinting (overprinting is poor) is: first, in multicolor overprinting, the previous color is not dried and then the next color is printed; second, the post-printed (ink) color causes the previous color to peel (bite); The printed color ink sleeve (stack) cannot be printed; the fourth is that the ink film is crystallized or no longer wettable (the ink film is not slightly soluble).
The treatment methods are: one is to increase the drying speed of the previous color; the other is to reduce the viscosity of the latter color or reduce the printing pressure; the third is to increase the viscosity or adhesion of the latter color; the fourth is to increase the pH of the ink or add an appropriate amount of wetting aid Agent.
6. The sleeve (overlay) cannot be printed. The reasons are as follows: first, the previous (color) drying is too fast or crystallizes or has no resolubility. The second is the warping and warping caused by the paper absorbing ink, moisture, and even non-absorbent plastic.
The processing methods are: one is to print the first color after the front color is not completely dry; or to add a suitable amount of solvent or increase the pH value; the second is to master the timing of the subsequent color printing or change the paper; add an appropriate amount of diluent or change the stretch Stable ink.
7. Overprinting is not allowed because: First, the tension of the printed material is not uniform; second, a bearing at both ends of the printing plate is worn or the plate roller is not through; third, the printed material has lotus leaves; the fourth is the previous color The printing pressure is too large, which deforms the pattern; the fifth is the unevenness of the joints of the substrate or the thickness of the two sides is different; the sixth is the printing plate swelled and deformed by the ink.
The processing methods are: one is to adjust the tension of the retractable material (substrate); the second is to check or replace the worn or deformed plate roller; the third is to adjust the tension or replace the substrate; the fourth is to adjust the printing pressure; the fifth is to reconnect; the sixth is Replace with a new plate.
8. The color is unstable. The reasons are: First, there is a change in viscosity and pH; second, there is a deviation in the ink distribution process or printing operation program.
The treatment methods are: one is to readjust the viscosity or control the pH adjuster; the other is to check the ink distribution process and operation process.
9. The color is too light. The reasons are: one is the viscosity is too low; the other is that the anilox roller is too thin; the third is that the anilox roller is worn or not cleaned; the fourth is that the amount of ink is too small.
The processing methods are: first, increase the viscosity of the ink; second, replace the anilox roller with a thick anilox; third, replace with a new anilox roller or thoroughly clean the anilox roller; fourth, speed up the printing speed or reduce the pressure of the ink transfer roller.
10. The color is too dark. The reasons are: one is that the viscosity of the ink is too high or the color strength is too strong; the other is to add a lightening agent to reduce the depth of the ink color; the third is to increase the pressure of the transfer roller or reduce the ink additives in the ink system.
The treatment methods are: firstly, adding a diluent to reduce the viscosity of the ink; secondly, the anilox roller is too rough; thirdly, the amount of ink is too large or the ink system has too many ink additives or fillers.
11. Ink color unevenness The reasons are: first, the printing plate is uneven; second, the thickness of the substrate is uneven; third, the screen line of the anilox roller is too low; and fourth, the anilox roller has dry or residual ink.
The processing methods are: one is to grind the back of the printing plate or to correct the stickers; the other is to change the substrate with a uniform thickness; the third is to replace the anilox roller with a high number of screen lines. The fourth is to clean the ink residue remaining on the anilox roller cavity.
12. The reasons for poor ink film adhesion are: first, the ink quality is poor or the wrong ink is used; second, the substrate does not meet the processing requirements; third, the wrong thinner is used, the printing pressure is too small or the ink layer is too thick; the fourth is the ink The tinting power is too low.
The processing methods are as follows: firstly, changing the suitable ink and ink; secondly, controlling the processing of the substrate; thirdly, using the corresponding thinner; fourthly, increasing the printing pressure or selecting inks with good tinting strength or reducing the ink supply.
13. The gloss of the ink is poor. The reasons are: first, the ink is of poor quality or has a certain permeability; second, the substrate is too rough and the viscosity is too low. Generally, the viscosity should be: 40 ~ 60, and the gravure is 18 ~ 25S / 25 ℃. 4 cups).
The processing methods are: one is to exchange high-quality ink (especially the same in the dry surface of the ink system); the second is to exchange the flat surface or impermeable substrate (or the ink that does not penetrate the paper); the third is to control Ink viscosity: 35 ~ 60S / 25 ° C · Coat 4 cups. The fourth is to add rosin modified ink with high pH value or high molecular weight acrylic resin ink or coupling agent to remedy it.
14. Ink fading due to ink printing The reasons are as follows: first, the color of the filler in the ink is different or the color with a different wavelength is used; second, the color is poor in alkali resistance and heat resistance.
The processing methods are: first, replace the non-absorptive calcium-based fillers or choose pigments with similar color wavelengths; second, choose alkali-resistant and heat-resistant pigments; third, switch to light-resistant pigments or add appropriate amounts of ultraviolet absorbers or add Antioxidant 0.1 ~ 1.0%.
15. The picture and text are fuzzy, fuzzy, and burrs are caused by: first, poor printing quality; second, the printing plate is in too close contact with the ink roller; third, the ink viscosity is too large or the ink returns to thick; Fast; five is the impact of environmental dust and so on.
The processing methods are: first, the pad should be flat and consistent; the second is to adjust the pressure between the printing plate and the ink roller; the third is to adjust the viscosity of the ink and mix the water or alcohol (or ester) or reasonably stir the ink or increase the coupling The proportion of the agent; the fourth is to reduce the drying speed, and the fifth is to control the environmental dust.
16. Graphic and text collapse The reasons are: first, the printing plate is too soft or the pad is too elastic; second, the contact is too tight or the printing pressure is too large; third, the ink viscosity is too low.
The processing methods are: first, the pad should be suitable, or the height of the printing plate should be adjusted; second, the printing pressure should be adjusted or the plate roller should be loosened; third, the ink should be replaced with a high viscosity, high hardness ink or an appropriate amount of stirring the ink.
17. Pinholes in ink film The reasons are: one is excessive dilution of the ink; the other is insufficient internal defoaming aid; the third is that the viscosity of the ink is too low and the ink is too much.
The treatment methods are: firstly, adding an appropriate amount of the original ink to the ink; secondly, controlling the amount of the internal and external defoaming agents; and thirdly, adding an appropriate amount of the original ink and stirring well.
18. The printing plate is worn The reasons are: the printing is too heavy; the second is the contact is too tight; the third is the poor quality of the printing plate; the fourth is the ink or thinner corrodes the printing plate.
The processing methods are: one is to adjust the printing pressure; the other is to adjust the contact; the third is to replace the new version; the fourth is to change the ink or thinner that does not corrode the printing plate.
19. The prints are spotted. The reasons are: one is that the ink is too thin; the other is that the surface of the substrate is uneven; the third is that the viscosity of the ink is too small; the fourth is that the printing plate is uneven in ink.
The processing methods are: one is to add coupling agent 200S or original ink; the second is to use a slightly elastic ink or a uniform thickness of the printing material; the third is to use a high viscosity or high viscosity ink; the fourth is to adjust or check the ink delivery system.
20. The printing ink dries too fast. The reasons are: first, the printing speed is too slow; second, the open time is too long, the ink drying speed is too fast; the ink viscosity is too large; and the drying temperature is too high.
The processing methods are: one is to increase the printing speed, the other is to increase the diluent; the third is to add a slow-drying dilute real solvent; the fourth is to reduce the drying temperature or eliminate the drying system facilities.
21. Print-through of printed products The reasons are: one is that the ink is too thin; the other is that the substrate is too rough; the third is that the ink dries too slowly; the fourth is that there are excessive spherical pigments or surfactants in the ink system.
The treatment methods are: first, adding original ink; second, changing the surface of the flat printing substrate; third, changing the fast-drying ink; fourth, using non-spherical pigments or controlling the amount of surfactant.
22. Blocking and pasting The reasons are: first, the printing plate is too shallow; second, the printing pressure is too heavy; third, the ink supply is too high; fourth, the ink viscosity is too high; fifth, the ink drying speed is too fast.
The processing methods are: one is to use the deep version; the other is to adjust the printing pressure; the third is to reduce the ink supply; the fourth is to dilute the ink; the fifth is to reduce the drying temperature or add a slow drying agent or increase the printing speed appropriately.
23. Sticky pages and smudges are caused by: first, the film formation of ink after printing is too slow; second, the tension of rewind paper or plastic is too loose; third, the product is piled up and heated; fourth, the softening point of the resin of the ink system is too low; It is the plastic back of the substrate that was mishandled.
The processing methods are: one is to switch to fast-drying ink or increase the drying (or downwind) temperature; the second is to increase the fast-evaporating diluent solvent or to add a catalyst; the third is to reduce the tension of the rewinding; the fourth is to detect the processing before printing Substrate.
24. Ink film drying is too slow The reasons are: first, the printing speed is too fast; second, the ink (system) is too slow to dry; third, the drying temperature is low.
The treatment methods are: one is to reduce the speed of the printing machine, the other is to add a fast-evaporating diluent or catalytic drier; the third is to increase the ambient temperature or increase the temperature or increase the blowing.
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