Water-based packaging printing ink containing coupling agent (2)

Third, the impact of ink quality and exclusion measures 1. The relationship between printing conditions, dry speed, and gloss is used to print water-soluble flexible letterpress and gravure and screen printing screen printing inks for packaging paper bags, books, and cartons, with low cost and poor gloss. In the past more than a decade, gravure carton tanks made of high-polymer acrylics have been used, but there is still a long way to go to meet the luster of users. Because of the paper density problem of carton packaging materials, coupled with the large water ink molecules, only the addition of coupling agents to increase the degree of branching is the focus of research.
In addition to the above, the temperature and humidity of the printing shop is also related to the drying and gloss of the prints. Temperature is the main condition for the promotion of oxidation polymerization and the formation of volatile ink film. Therefore, in the summer and winter, the difference between the dryness of the ink in the southern coastal area and the northern highland area is about twice as high.
The temperature of the printing shop plays a role in retarding the oxidation polymerization and volatilizing the firm ink film on the dried products of printing products. Relative humidity of 95% and 65% compared to the drying time almost two or more. At the same time, the dry humidity of paper, plastic, and fabric itself will directly affect the drying time of printed products.
Acidity will retard the oxidative polymerization of the ink and the formation of volatile solid ink film. Excessive alkalinity will lead to internal wet (dry skin chary) and affect the product's adhesion. For example, a paper with a pH of 4.5 delays the drying time of the paper by a factor of 3-5 compared to a pH of 7 paper. For the same reason, the pH value of water-based ink system often falls from pH 8 to 3.5, and the dry speed of printed products will also be 3-4 times longer.
Because oxygen or air blow is a factor that promotes the formation of oxidative polymerization and the formation of volatile solidified ink film, the degree of ventilation in the press room and the way in which prints are stacked are also related to the dry speed of the printed product. The slow speed of printing will make it difficult to overprint or cut the next process, and the phenomenon of sticky backs and faded colors will occur. On the contrary, it also makes it difficult for the second printing ink to adhere.
The inks with different specific gravities can be co-located together after adding the TM-200 coupling agent to the bridging bridge. This peculiar architecture environment is very beneficial for today's new material processing, new product manufacturing, and rapid high-performance packaging and printing.
The pH value is the key to the success or failure of ink ink manufacturing and printability technology. If the adjustment is not good, you will not get high quality prints. First of all, from the analysis of ink components, due to the combined use of alkali-soluble binders and emulsion polymers, even excessive dispersion leads to a large amount of foam, it can also promote the stability of the ink, so that the range of ink functions and printing and decorating features are expanded. . The stability of the colorant and the carrier system is based on the pH buffering and the coating of the coupling agent to achieve resistance to external acids and bases, and to maintain the stability of the aqueous ink in a certain range. Whether it is based on alkali (amine), ammonia, etc. added to the resin for acid neutralization and dissolution, or latex manufacturing technology is very different (the resin is a non-soluble continuous liquid) in water polymerization, even if the starch water insoluble matter still accounts for 26% as much. We know that it is dispersed with fine particles but it is not completely dissolved. These hundreds of thousands of small particles wander in the water without conflicting each other because the particles are charged and the co-surfaced ink inhibits their combination. This is due to the use of surfactants, protective adhesives and additives. result.
In the manufacturing or printing cycle of the ink, the volatile alkali is evaporated and often causes the pH value to drop, which causes the carrier system to become unstable, loses the ability to stably exist in the ink system, starts to solidify, and the viscosity is obviously increased. The operating staff often Misconception is caused by water shortages. I would like to use the replenishment method to make adjustments and remedy. I wonder if this dilution and low pH will further aggravate the instability of the ink system, often causing it to lose its transferability or discoloration. Even the loss of stability has occurred. The general pH value is controlled between 8.0-9.3.
Second, when the pH value of the ink in the ink fountain is too low, it can cause drying of the metal anilox roller and the plate. In the transfer process, the ink will volatilize some alkali (amine) and ammonia, and the ink ink recoils from the ink hole and the plate. In the graphic version, the printed matter is contaminated or the metal anilox roll is blocked, ie, the amount of ink is insufficient. It is often difficult to wash the printer with water after printing with a rotary diaphragm vacuum pump.
There is also a situation where the pH value of the ink fountain is too high, which is often caused by the adjustment of the operating staff. These remaining alkalis cannot be eliminated during the printing process. Even if the amount of alkali is small and the time is long, the water resistance of the ink film is difficult to reach. High value. This is because the base is physically closed after the formation of the ink film, so the ink film will never reach sufficient water resistance, adhesion and gloss.
In addition to the above-mentioned factors, the ink pH value, the printing medium pH, the ink, or the dry, glossy, paper surface, plastic surface, fabric surface (such as rosin ester, clay, etc. used in paper sizing, and each has its own characteristics). The ink painting also has an effect. When the ink is printed on the surface of the paper, it will be affected by the pH value of the printing paper. When the acidity of the paper is high, the coupling agent used as a driers in the ink does not work, the alkali in the ink is neutralized, and the dryness is advanced, and the paper alkali is advanced. High-quality, slow-drying inks sometimes limit the ink's ability to resist water completely.
2. The reason for the failure of the ink and the exclusion method are inaccurate. The ink viscosity is too low or the content of the pigment in the system is small or the color purity is deviated. The ink separates and precipitates during printing, and the ink is stirred unevenly and cannot be transferred. Incorporate the original ink, adjust the viscosity, stir the ink and then print, check the printing plate and the ink roller for aging.
Viscosity instability: The ink has thixotropy, foaming, solvent volatile, the ink should be used after stirring evenly, add appropriate amount of oxime foaming agent (0.2%), add the appropriate amount of solvent to achieve the balance of volatilization speed.
Poor drying (except for the above): When the expected time, the imprinting is not dry or even sticky; the ink viscosity is high, the outline edge is not dry, the ink is not dry, the absorption of the base paper or plastic, fabric is poor, the diluted ink , adjust the printing pressure, pay attention to the pad version, use quick-drying ink, or adjust the dryness, exchange the substrate.
Blurring of contours: the high-profile part of the printing is blurred, the dots are missing and the tone is lost, the quality of the printing plate is not high, the printing plate and the ink roller are in tight contact, the viscosity of the ink is large, the ink is thick, the ink dries too quickly and the mixing is bad. Pad plate should be evenly leveled, adjust the printing pressure, adjust the ink viscosity should be mixed with water and alcohol, reasonable mixing of ink, adjust the ventilation device, do not blow to the plate, ink roller, and increase the speed, with water containing - ethanolamine Scrub or add about 0.2% simethicone or increase the coupling agent ratio. (To be continued)

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