Analysis of the main factors affecting the quality of ink and color printing

In terms of printing chromatics, the color printing process is essentially a process of "decomposition" to "synthesizing" colors, and our colors have become darker and darker during the more than 20 years of ink-to-print printing. And discoloration and water insolence or dullness are undesirable to us. However, we have the responsibility to pay attention to this focus of many years in manufacturing and use, and to enumerate some of the points in the packaging printing industry for pure technical communication, and strive to reach the ink and wash The quality of other inks. 
First, the theoretical analysis of ink transfer failure Water-based inks, especially water-washable inks in the structure of the difference is the rise in pH; ink price competition with the market was forced to use inorganic pigments, the result of the color ink does not Stability - deepening, darkening, fading fade (gloss), has become one of the focuses of joint research at home and abroad. 
We know that the chemical stability of color ink is related to the chemical nature of the colorant used in the ink system. Inorganic pigments are generally more active than organic compounds. This is because inorganic compounds are soluble in water and are easily ionized into ions. The reaction between ions can be completed instantaneously, while the organic compound pigments are the opposite. Therefore, it is said that it is suitable for washing in ink and water, and it is also relatively less polluted with respect to the environment, but its chemical stability is poor, for example, when organic chromium yellow is easily changed to red after encountering alkali.
Another focus is that we tend to emphasize the use of contrasting colors to enhance the visual stimuli - distinctive and eye-catching personality after juxtaposition. The use of color-contradictory colors to juxtapose them together, with an uncoordinated approach to deepen consumers' impressions of package printing and decorating. However, I do not know that when organic and inorganic inks are used in the three-primary system, when the contrast color (area, brightness, and saturation) changes, the intensity of contrast will also change. When it comes to acid and alkali, it will often appear transient. To reconcile, with the passage of time, juxtaposition of color ink will be dark to dark or light, achromatic, and dull. Whether it is the organic pigments in the ink system that cause the hue of the organic pigments to darken or darken, or the inorganic pigments in the ink system encounter alkalis, the color hue becomes dark and fades until it fades. )reduce. This kind of physical or chemical change is not often called the hue deviation accident caused by the unequal quantity or purity of the three primary colors and the gray balance. It is mostly due to the fact that the ink is mixed with a few metal oxides that are both sexes. Strong alkalis become acidic and darken; in the case of strong acids, they are alkaline faded and extinct. Although the eye fatigue caused by glossiness is reduced, the efficiency of reading increases, but it is often difficult to achieve a bright appearance of the packaging and decoration of trademarks and product samples due to the deviation of gloss. This subjective or objective assessment of the quality of water-based color inks is often Based on similar products. But only one point is the same - pH.
When we were exploring water-based color inks around pH, when we consulted Alanius, Browns, Laurel, Louis, and other authoritative theoretical theories about acid and alkali, especially when it comes down to this phenomenon : In the aqueous solution can not only ionize to produce hydroxide (OH) but also ionized to produce hydrogen ion (H+) will happen, two kinds of metals in contact with each other, interdiffusion to the inside and so on. It will be understood that due to the above reasons, increasing the amount of alkali causes the ink system, especially the alkaline printing ink film, to be in an unstable state after being printed on the substrate (the remaining trace amount of alkali is temporarily blocked, and once contacted with water, the ink film It will be destroyed, and under the action of external force, the ink dripped from the sphere into an irregular mixture, and then the dry ink film formed on the surface will be rough and dull. 
Although there are few thixotropy systems and osmotic condensation systems in the breakdown of ink and wash, it is worthwhile to analyze this issue gradually. The above difference is nothing more than: the former is at a certain speed, the shear force decreases with time, the latter is the contrary, the grasp is not good, not the color hue is difficult to stabilize, is to bring endless printing problems. For many years, when we were thixotropy, we often neglected the indirect thixotropy. The simplest difference is that the oscillating ink system becomes a gel under the external rhythm of vibration, and its rhythm and vibration can be gently. Beating, regular round motion or pendulum agitating, that is, if there is no external effect, it will not cause the ink to form condensation. When the solid content is about 1% to 2% and the particle is not symmetrical, it forms a gel completely. Is the result of particle orientation. 
From a microscopic point of view, we are observing another type of ink thixotropy, which is the cause of the malfunction. The feature of the swellable ink system is that when the excision is removed, the viscosity of the ink system is immediately "thinned." The swellable ink system suspension is highly concentrated and low in nature. General solids content up to 40%, good wetting properties. If we increase temperature or increase the pH, the concentration decreases and the viscosity increases, or if some of the water is added in an appropriate amount, it does not resemble a condensable ink. When the external force is removed, the system will remain in a solid state (this phenomenon Although it is rare, once it does occur, it is really a headache.) At least for a while, it is in a solidified state and then thinned. However, ink is completely resistant to water and discoloration can no longer be avoided. 
In solving the above two kinds of condensing failures, especially the rare oscillating ink system, we have solved practical problems, especially in terms of difficulty, which is more important than the oscillating ink system, and it is difficult to know how many times it is. . We know that the recovery of thixotropic structures from structural to non-structural, or from the deconstruction of structures to the recovery of structures is the process of isothermal and reversible transformation. The second is that this repeated transformation of the architecture is related to time, that is, the destruction and formation of the structure is a function of time. At the same time, the mechanical strength of the structure also varies with time. The deformation of the ink system produced by the shear force of this object (if the f/D ratio is temporarily reduced, the system has thixotropy), can be seen as the “gel-sol” of the water-based color ink system at a constant temperature. The performance of the mutual conversion process. The viscosity of a large-scale ink under the external force stirred, the state of its destruction was destroyed, with time, with the increase of time, with the decline of the ambient temperature, the state of its condensation gradually increased, until the restoration of the original state.
It is known that adding a certain amount of macromolecule compounds or associative colloids to a hydrosol can significantly increase the stability of the sol to electrolytes before the 1980s and call it a "protective effect," and since the 1980s it has been called " Space stability." Regardless of how it is called, the use of animal glue in the ink system for thousands of years will enable carbon black to be stably suspended in water. Although no thixotropy is required for rotary ink (flexible letterpress printing ink or gravure printing ink), in order to stabilize the ink, the stability during storage is often achieved by the method of using the emulsion and the solution binder, but this method of ink manufacturing Although the method is more scientific than a single resin solution and can prevent precipitation or delamination of the ink in storage printing, it will inevitably lead to different degrees of thixotropy. In severe cases, the ink is not easy to pour out of the ink tank. After stirring, the effect is slight. The normal fluidity of the transfer of the printing ink will affect the ink transfer in the ink fountain and the pump tube and even block the pipeline and transfer the ink. In a word, scientific pH control always affects thixotropy, especially the graphic effect of ink packaging printing. 
Second, the practice of rotating packaging color exploration around the color printing this issue, we use an alkali, ammonia, amine neutralizing agent too fast or unscientific addition amount in the process of anatomical preparation of ink, forget that the pigment was not all but part of the beginning Gradually wetting and destroying the surface structure of the pigments and dyes, when scratched or printed, the gloss of the ink film will be reduced, or even completely glossless. At the same time, the addition of excess water molecules will also reduce its gloss. However, the fundamental difference between these two categories is that the former is caused by the dripping of pigments, dyes, or acidified ink-and-wash systems caused by strong alkali-flocculated ink-and-wash systems—dark shades of color hue and fading; while the latter is Excessive water intrusion causes a rapid drop in viscosity (eg, high gloss viscosity is usually 45-60s/coating 4 cups at 25°C. When 17再5% water is added, the viscosity drops rapidly to 18-25s. / Coated 4 cups, 25°C matt or micro-gloss packaging printing ink film / 250g liner paper). This results in a decrease in the content of the solid resin, which is caused by the richness of the color hue to the faintness of the polymer. Although the surface appears to add water, the polymer binder is in a stable and curled state, and when the external force acts to extend the structure of the segment until the molecule breaks. The printed ink film has no glossiness.
Another situation is: In order to reduce the cost of materials and completely use natural rosin with a molecular weight of only 330, in order to achieve the stability of the ink system space, in recent years, we have used dozens of inorganic materials that do not cause changes in chemical properties. The porous morphology of the tetrahedral hydrated silica acts as an associative colloid, enabling it to be stably adsorbed on the surface of the low molecular weight rosin sol particles, forming a protective film, stretching the lyophilic groups into the water, both Can eliminate thixotropy and improve its water washability, and has a certain thickness, especially when more than 5% of the packaging and printing ink film to form a layer of short and thick low molecular ink film, then it will reduce The viscosity of the ink, while increasing the concentration, affects both the flowability of the printing transfer and the improvement of the gloss, which may be due to an increase in the temperature of the ink system and a decrease in the association tendency of the rosin molecules during the association heat release process. In this regard, we selected the TM-200S coupling agent (tackifier) ​​from Yizheng Tianyang Chemical Factory to improve the strength of the resin joints and increase the adhesion of the glue to the adhesive surface, thus effectively preventing the adhesive layer. The peeling and peeling from the glued surface not only promotes the heat and moisture resistance of the glue in the ink system, but also increases the bond strength between some difficult-to-stick materials and the low-molecular-weight resin sol, the pigment and filler, and the gloss of the packaged ink film. And water washability. This is that the paint film should be hard and the ink film should be soft. 
Followed by the use of alkali-resistant pigments or dyes or fillers. Most of the dyes are used in light-packed ink-in-water resins (whether natural or synthetic, whether high or low molecular weight resins) that do not require lightfastness. They need to have dispersibility, transferability, quick-drying, gloss, and abrasion resistance. Rubbing. At present, shellac and even acrylic resin have been replaced by pure rosin resin (to be tested before use). The traditional method for preparing the resin liquid material with a temperature-enhanced modification has been replaced by a method for preparing a rosin resin liquid material at room temperature. A green ink which is almost completely free from environmental pollution has been favored in the market. 
Solvent, traditional production is distilled water (ion water is the best), especially ethanol or isopropanol is needed, and most of the market now uses tap water or groundwater. Under strict compliance with the pH index, trace addition is active, bridging and increasing. Sticky TM-200S coupling agents have changed the production (process) method of making ink. 
Third, the main subject to be technical exchange In addition to the success or failure of the discussed exchanges above, some of the following list, although they can overcome, but it is easy to repeat the mistakes that have been made. This article tips out for everyone to discuss. 
1 For example, in the recovery of inks made from rosin resin, white ink or black ink made from an alkali excess chain material and a slightly acidic titanium dioxide or carbon black tends to result in poor ink flow due to secondary neutralization of acid and alkali. Edition, forming a non-glossy packaging printing ink film.
2) The addition of cheap talcum powder can make the ink easy to hang and not easy to ink (in contrast to acrylic ink).
When adding a single defoamer in excess, the foam in the ink film cannot avoid chemical pinholes before curing and drying. When the ink is cured and dried, printing the ink film will result in orange peeling of the pattern, even if the filler is used. Eliminated, but leaving the ink film color deviation. 
4) Hydrated silica or magnesium salt as an associate, when the purpose of thickening and anti-settling is reached, the ink film will still have a certain degree of gloss, and an excessive amount will be counterproductive. 
Although the use of 5 color primordium or basic dyes is small, the water can be washed well, but it is not easy to wash after contact with the flexible letterpress and human skin.
Although inorganic inks can overcome water washability, printing inks are prone to precipitation or delamination, and the ink layers are thickened and the dots are lost.
Excessive dispersion of 7-ink ink often exacerbates the swelling of the pigment fillers of the system, and it is more difficult to control the accumulation of ink particle size aggregates when the aggregates are aggregated and rebounded or coagulated than when misused with an active solvent molecule.