The main factors affecting the color printing ink quality analysis 2

General solids content up to 40%, good wetting properties. If we raise the temperature or increase the pH, when the concentration decreases and the viscosity increases, or if some amount of water is added, it will not be like a condensable ink. When the excisional force is removed, the system will remain in a solidified state (although this phenomenon is rare, once it is indeed a very headache), at least a period of time is a solidification state, and then thinning. However, ink is completely resistant to water and discoloration can no longer be avoided.

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 an ink system produced by such a body under shear force (if the f/D ratio is temporarily reduced, the system is thixotropy) and can be considered as a water-based color ink system at a constant temperature. The performance of the process of mutual conversion between. 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 the electrolyte before the 1980s and call it a “protective effect”; after the 1980s it was 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. For rotary ink (flexible letterpress printing ink or gravure printing ink), although there is no thixotropy, in order to widely stabilize the ink and ink, the emulsion and the solution linking material are often used to achieve the stability during storage, but the ink is manufactured. 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 printing ink transfer will affect the ink transfer in the ink fountain and the pump tube and even block the pipeline without ink transfer. In a word, scientific pH control always affects thixotropy, especially the graphic effect of ink packaging printing.

Second, the reasons for the failure of packaging color printing

Focusing on the issue of color printing, we analyzed the amount of alkali or ammonia or amine neutralizing agent added too quickly or unscientifically during the preparation of ink painting, ignoring the fact that the pigment was not totally but partially gradually wetted in the beginning. As a result, the surface structure of the color and the dye is damaged. When the sample is scraped or printed, the gloss of the ink film is reduced, and even the gloss is completely absent. At the same time excessive addition of water molecules will also reduce its luster. 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 in the ink system where strong alkali causes flocculation; the dark shades of color hue and matting fade; while the latter is water. Excessive intrusion caused a rapid drop in viscosity (eg high gloss viscosity tends to be 45-60s/coating -4 cups at 25°C. After adding 17.5% water, the viscosity drops rapidly to 18-25s/coating. - 4 cups at 25°C to form matt or micro-gloss packaging printing ink film/250g liner paper). This is due to the reduction of the solid resin content, from the dense to dilute color hue. Although the surface of the polymer binder appears to be in a stable and curled state after the water is added, once the external force acts, the segment structure is extended to the molecule. The printed ink film has no glossiness.

Another situation is: In order to reduce the cost of materials, we only use natural rosin with a molecular weight of only 330. To achieve the space stability of the ink system, in recent years, we have used four sides in dozens of inorganic materials that do not cause changes in chemical properties. The porous form of hydrated silica of the body 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, and extending the lyophilic groups into water, which can eliminate The thixotropic can also improve the water washability, and has a certain thickness, especially when it exceeds 5%, the printed ink film forms a layer of short and thick low-molecular ink film, and at the same time, it will reduce the ink. Viscosity, if the concentration is increased, will not only affect the flowability of the printing transfer, but also affect the improvement of the gloss. The reason is that the temperature of the ink system is increased and the association tendency of the rosin molecules is weakened in the process of associating heat release. .