Application methods and precautions for green packaging ink

Water-based printing inks for green packaging have been used for printing on the surface of absorbent materials on webs for more than a decade. The use of modern technology will be the domestic high-performance additives and pure natural resin rosin directly into the ink system, so that the ink used in flexible packaging plastic film, plastic textile bags, calcium plastic carton, leather and other materials printing and non-absorbing materials Printing on the surface becomes a reality. When printing, the traditional ink manufacturing process and technical indicators of the same use at home and abroad are slightly different, but the principle of printing and packaging is the same.

According to the two major categories of liquid and paste inks with different colorants, auxiliary binders, fillers and auxiliary substances, certain fluidity and fluidity, the following three classification methods are applied:
According to the printing plate classification, there are flexible letterpress inks, gravure printing inks, and stencil printing inks and roll coating inks.
According to the main ink classification, there are web and cardboard 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, pure green packaging printing ink is an industrial product for packaging products and can be used for printing newspapers, magazines, food, packaging printing and decoration. Although paper, plastic, leather, etc. can be printed with green ink, due to the late start, there are many defects in the application method. For this reason, according to the methods outlined in the past few years, and the prevention and resolution of failures, the author provides reference for packaging colleagues.

In colloid chemistry, the property of reducing the surface tension of a solvent is called surface activity, and the substance that can reduce the surface tension of a solvent is called a surface active material. According to this theory, Rosin Soap can be used as a surfactant, coupled with experimental data on the compatibility of rosin and non-polar polyalkenes at high temperatures, which significantly changes the interfacial tension of the system, eliminating the need for corona Treatment has a firm adhesion.
In the daily packaging and printing business, green packaging inks are relatively thin, and are mostly used in operations such as flexible rotary printing, rotogravure, rotary screen printing, and single-ply pneumatic diaphragm pumps for water-soluble printing paperboards. To overcome the ink delamination and often, winter ink jelly and thickening that affect the normal packaging printing, we added a network structure to the components of the ink and can contain -OH hydrophilic alcohol-based ions in the crystal lattice. The state-of-the-art inorganic and organic high-efficiency dispersion materials enhance the vicious circle of anti-electrolyte and stabilize the ink. Although sometimes it is like searching for joints, due to factors such as ink quality, printing materials, operator skills, and other factors, it will not be clear at one and a half moments. Therefore, the above situation is summarized as failure phenomenon. Remedy. We look forward to feedback from industry colleagues on timely feedback to break through the regional and system boundaries to improve green packaging and printing ink formulation and process design to create a brilliant future.

Common ink failures and solutions:

1. The graphic and graphic inks are light and the inks are not clear; the ink is light, the ink is hard, the printing pressure is low, the ink's transfer rate and adhesiveness are poor, and the black ink is even condensed in the printing process and is difficult to handle. Rough.
Solution: Adjust the amount of ink and viscoelasticity, adhesion fastness, improve the printing speed, reduce the printing pressure, increase the viscosity of the ink, add high-efficiency ultra-disperse additives in the ink to improve the ink transfer rate, adjust the printing pressure and select the smooth surface Material, dilute ink viscosity, increase ink drying speed.
2. Crushing and smudging Imprinting causes ink prints to become dirty, print pressure is large, the layout is poorly elastic, or the rollers are denatured and not smooth.
Solution: Adjust the ink dry speed or reduce the amount of ink, reduce the pressure of the roller, must change the flexo and calibration pressure roller.
3. The back of the dirty and bite-colored print is dirty or overprinted by the previous ink mark, or the ink on the transfer belt of the embossing roller is transferred to the next substrate; in the ink, the dryness is too slow and the second color is printed. Sticking 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, the thickness of the printing material on both sides is inconsistent, or the winding tension is inconsistent.
Solution: Increase the initial dryness of the ink, increase the proportion of lubricating anti-adhesive agent and in the ink, add a quick-drying solvent or oil to increase the hot or cold blow or slow down the printing speed and extend the printing stroke, choose absorbency or Surface roughening of the treated material improves the surface absorption of the substrate, and attention should be paid to the stacking of printed materials not too high or too heavy.
4. Ink splashing There are different ink spots or ink droplets in the print shop. The ink has a large yield value, high viscosity, ink layer thickness and ink film separation is too long or ink is too thin, the printing speed is too fast, the ink viscosity is too small and does not antistatic, poor precision of the printing press, ink roller deformation or surface Damage can cause ink splashes.
Solution: Replace the ink roller, reduce the viscosity of the ink and reduce the drawing length and fluidity, reduce the supply, high-speed ink viscosity, slow down the printing speed, adjust the temperature and humidity of the workshop, replace the ink roller and repair equipment or add antistatic facilities And materials.
5. Plates, ink rollers dirty and scratches Plates and rollers are stained by ink on the printed material; ink is too small and has high viscosity, impurities in ink, ink drying too fast or too slow, plates and rollers The electroplated layer on the bar is worn, the hardness is not enough, or the pattern is too deep, and dust such as paper and plastic is increased.
Solution: Replace the double-sided tape, adjust the pressure, adjust the angle between the blade and the roller, reduce the amount of ink or replace the ink, increase the speed of the oil, repair the version and roller, re-glazing chrome, prevent paper, plastic and other powder dust Fall off.
6. Poor adhesion and rubbed dirty prints are easily wiped off. The surfaces of paper and plastic materials are too smooth and dense. It is not appropriate to use slow-drying inks. The ink resin content is too small, and the surface treatment is poor. It cannot be dried and floated on substrates at one time. It is easily wiped off on the surface.
Solution: Improve ink type, adjust ink suitability, process printing materials, use ink with high viscosity and high ink density, increase printing pressure, reduce thickness of ink film, reduce printing speed, and use high-efficiency additives and viscosity-increasing inks. Replace the solvent or oil that affects the dryness of the ink, and replace the ink oil or thinner according to the ink's suitability.
7. Residual irritating odor The proportion of methanol in the ink is too high and there is an odor of solvent or oil.
Solution: Use as little ink as possible or do not use solvents or oils that are irritating or harmful to human health. Replace inks or replace solvents and oils.
8. Inaccurate hue and precipitation of ink The color becomes lighter and discolored, resulting in stencil printing. The quality is inconsistent with the sample, and the affinity of the pigment, filler and binder is poor; the storage is coagulated or severely stratified. This is because the stirring was not sufficient before use.
Solution: In the storage period, the ink should be stored in a cool, dry and cool place. The color tone should be adjusted as close to the hue of the sample as possible. You can also add 1%-3% white ink to the ink, or increase the filler to increase the coverage. force.
9. Chemical pinholes and mechanical pinholes appear in pinholes and skid-printed products; spots appear in full-page printing, ink overflows during printing, and large amounts of foam appear.
Solution: When the viscosity of the ink is too low, the proportion of new ink or resin must be changed to increase the viscosity, increase the flowability, increase the printing speed, and add a clouding agent and a plasticized defoamer when the foam appears, and eliminate the foam. For shallow patterns, 25-30um is appropriate.
10. Embedded ink and orange peel have high viscosity, many impurities, fast drying, unbalanced solubility, and unsmooth ink, resulting in the appearance of watermarks and orange peels. The ink residue and dried knots in the print pits, the printing gloss is poor, and the concentration is too light. The poor leveling of thixotropy is due to the poor affinity between the plate cylinder and the paper, plastics, etc., and the slowness of the auxiliary printing agent and the influence of static electricity.
Solution: The printing speed is adjusted to: high speed is about 0.012 seconds, medium speed is about 0.055 seconds, low speed is 0.09 seconds, single sheet is 0.012 seconds; hot air or cold wind blowing angle is 90 degrees, direct blowing or improved ventilation, additives Solvent to achieve solubility of solvents or oils and inks; replace ink auxiliaries, reduce static electricity, and adjust darkness as much as possible.