Application methods and precautions for green packaging inks

In order to catch up with the world advanced level, China's ink industry system was promoted in the mid-1970s by the “748” project signed by Premier Zhou Enlai personally. By the early 1980s, it was developed to meet the needs of printing and export packaging. , and developed from before and after the liberation of a small number of inks to write a variety of ink varieties have developed to light, fast solid, rotary, plastic, water-soluble gravure, electrostatic photocopying, light curing, more than 20 kinds of more than 300 Suits. At the end of the 1990s that will enter the 21st century, the trend of "eliminating white pollution and developing green packaging" has become an important part of the environmental protection industry.
Green packaging printing water-soluble ink has been printed on the surface of the absorbent material of web for nearly a decade. Modern technology has been used to directly introduce domestically-made high-efficiency additives and natural resin, rosin, directly into the ink system to make flexible packaging plastic film and plastic woven. Bags, calcium plastic cartons, etc., have become a reality when high-speed, multi-color printing inks are flooded in the market and they have begun to be printed and used on non-absorbent materials (plastics, aluminum foils, etc.). At the time of printing, it is slightly different from traditional domestic and foreign ink manufacturing processes and technical indicators, but the principle of printing and packaging is the same.
According to the composition of different color materials, auxiliary materials, fillers and auxiliary substances, liquid and paste inks with certain fluidity have two major categories, and their application classification methods are as follows:
According to the printing type classification, there are flexographic printing inks, gravure printing inks, and mesh printing inks and roll printing inks.
According to the main components of ink classification, there are web and board printing inks, alcohol-soluble printing inks and water-based printing inks.
According to ink use classification, there are paper printing ink, plastic ink and so on.
In short, green packaging printing ink is an industrial product that serves packaging products and can be used for printing newspapers, magazines, food, packaging printing and decoration. Although current paper, plastics, etc. can be printed with green ink, and has formed a mature Chinese national style ink new product system. Despite the late start and broad prospects, application methods and precautions have been put on the agenda of the printing industry. To this end, based on the problems that have been explored in the past few years, we must grasp the essentials of use, prevention of failures, and ways and means of solving them.
1, graphic and fuzzy, thin printing ink, graphic ink, strokes are not clear reasons are: less ink, ink hard, low pressure, ink transfer rate, poor adhesion, ink even in the printing process difficult to concentrate operating. Remedy: Adjust the amount of ink and viscoelasticity, adhesion fastness, improve the printing speed, reduce the printing pressure, increase the viscosity of the ink and add high-efficiency ultra-disperse additives, to improve the ink transfer rate, adjust the printing pressure and select the table surface slide material Dilute the ink viscosity and increase the drying speed.
2. Crushing and tamping the ink blots cause the prints to become dirty. The reason is: the printing pressure is large, the layout is poor in elasticity, or the pressure roller is deformed and not smooth. Remedy: Adjust the ink dry speed or reduce the amount of ink, reduce the pressure roller, change the flexo plate and correct the pressure roller.
3, dirty and plastic printed back of the print was dirty or overprint adhesion of the previous ink, or the ink on the transfer roller of the transfer roller is transferred to the next print. The reason is: the ink is too sticky, the dryness is too slow and uncomfortable, the second color printing is easy to stick off the first color, the surface of the conveyor belt is not clean or swollen, the printing pressure is too high, the machine speed is too fast, or the thickness of both sides of the printing material is not uniform Or the rolling tension is inconsistent. Remedy: Add a quick-drying solvent or oil, increase the proportion of lubricating anti-adhesive in the ink, increase the hot or cold blow or slow down the printing speed and extend the printing stroke, select the absorbent or rough surface treatment of the material, improve The absorption of the surface of the printing material, pay attention to the stacking load of the printing material not too high and too heavy.
4, ink splash in the printing shop with different sizes of ink or drop splash. The reason is: the yield value of the ink is large, the viscosity is large, the thickness of the ink layer and the ink film are too long when the ink film is separated or the ink is too thin, the printer speed is too fast, the ink viscosity is too small and does not resist static electricity, the accuracy of the printer is poor and the ink roller Deformation or surface damage. Remedy: Replace the ink roller, reduce the viscosity of the ink and reduce the drawing length and fluidity, reduce the ink supply, adjust the viscosity, slow down the printing speed, adjust the temperature and temperature of the workshop, replace the ink roller and maintenance equipment, or add antistatic facilities And materials.
5, version, ink roller sticky and scratched plate and ink roller is printed material on the ink sticky. The reason is: the ink is too small and the viscosity is high, the ink contains impurities, the ink dries too quickly or too slowly, the electroplating layer on the plate and the roller wears or the hardness is not enough, the plate count is deep, and the dust of paper, plastic and the like increases. . Remedy: Replace the double-sided tape, adjust the pressure and high-speed blade and roller angle, reduce the ink or replace the ink, increase the quick-drying solvent or oil, revision and roller, re-glazing chrome to prevent paper, plastic and other powder Dust off.
6, poor adhesion and wipe dirty prints easy to wipe off. The reason is: the surface of the paper plastic material is too smooth and dense, it is not appropriate to use slow-drying ink, the ink resin content is too small, the surface treatment is poor, can not dry and floating on the surface of the printing material surface is easy to wipe off, commonly known as skin coke bone Health. Remedy: Improve ink types, adjust ink suitability, process printing materials, use ink with high viscosity and high ink density, increase printing pressure, reduce ink film thickness, reduce printing speed, and use additives and viscosity-increasing inks. Replace solvents or oils that affect the ink drying gradient, exchange inks or thinners, and be aware of the ink's suitability.
7. Residual irritating odor The ink has a large proportion of methanol and is accompanied by odor solvents or oils. The reason is: The ink can reduce or not use irritating or harmful health or solvent. Remedy: Replace ink or replace solvent or oil.
8. Inaccurate hue and ink precipitation lighter, discolored, resulting in paste version, the quality does not match the sample. The reason is: poor affinity for pigments, fillers and linkages, coagulation or severe stratification (down-regulation). Remedy: Mix before use is not sufficient, the ink should be stored in a cool, dry and ventilated place during the storage period, the tone can be adjusted or exchanged to the sample hue close value, you can also add 1-3% of the white ink in the ink or increase Filler to increase its hiding power.
9. There are chemical pinholes and mechanical pinholes in the pattern of pinholes and sliding prints. The reason is that the printing plate has spots and the ink overflows and foams during the printing process. Remedy: When the viscosity of the ink is too low, the ratio of new ink or added resin should be changed to increase the viscosity, increase the fluidity, increase the printing speed, add moistening and plasticizing defoamers, eliminate foam, and the pattern depth should be replaced with plate pattern 25 - 30 micron is preferable.
10, buried version of orange peel and orange peel appearance. The reason is: ink viscosity, impurities, drying fast, unbalanced solubility, residue and dry knot in the print pit. Or the ink concentration is too light, the affinity between the printing plate roller and the paper, plastic, etc. is not good, the auxiliary agent is not suitable, the printing speed is slow and the static electricity. Remedy: The time required for the ink to transfer to the printing material, the high speed is about 0.012 seconds, the medium speed is about .055 seconds, the low speed is 0.09 seconds, the single sheet is 0.012 seconds, the hot or cold wind angle is 90 degrees straight Blow or improve the ventilation conditions, add its solvent, to achieve the solvent or ink and ink solubility. Replace ink additives, reduce static electricity, and concentrate darkness as much as possible. (Liu Jiaju)
Excerpted from China Packaging Yearbook 1999