The rheology of the ink has a certain influence on the quality and level of the printed product during the printing work. Then, the properties of the various rheological properties of the ink are analyzed below, thereby obtaining a specific influence on the printing work.
The rheological properties of the ink include ink viscosity, adhesion, yield, thixotropy, fluidity and flow, and transfer properties.
1. Viscosity
Viscosity is a measure of the ability of fluid molecules to attract each other and hinder the relative movement between molecules. It exhibits a property of stopping flow in the fluid and the extent to which it resists flow.
When the fluid is flowing, depending on the structure and properties of the fluid, it will be difficult to flow when the fluid is in a viscous state, and the fluid will flow smoothly when the fluid is in a thin state. The reason for this phenomenon in the fluid is that there are fluid molecules in the reflow. The resistance to exercise caused by attraction is called internal friction. This property of fluid is called viscosity.
Viscosity is an important indicator of ink rheology. The certain viscosity in the printing process is the main condition to ensure the ink support transfer and uniform transfer, because it is related to the smooth progress of the printing process, and directly affects the uniformity of the ink color. , clarity and gloss.
Improper control of ink viscosity during printing can cause a variety of failures in printing. as follows:
(1) When the viscosity of the ink is too large, the viscosity is too large and the stringiness is strong. During the ink transfer process, the filament ends are too long when splitting between the ink rollers, and the ends of the broken filaments are likely to form ink scattering into the air, forming a flying ink phenomenon in printing, and the flying ink phenomenon is more obvious in high-speed printing.
(2) If the viscosity of the ink is too large, it is easy to cause the powder to be removed, pulled or delaminated. This is because the adhesion of the ink exceeds the surface strength of the paper under certain printing conditions. This phenomenon is more pronounced when the structure of the printing paper is loose and the surface strength is not high.
(3) When the ink is transferred and transferred between the ink rollers, the excessive viscosity makes the ink transfer difficult, because the ink transfer rate is inversely proportional to the viscosity, so too much viscosity will result in uneven distribution of the ink, transfer to the printing plate or The amount of ink on the printed matter is insufficient, the ink is uneven, and the appearance of the printed graphic is exposed.
(4) Excessive viscosity of the ink will have some other effects on the printing process. If the amount of ink is increased during the printing process, the ink layer of the printed matter is too thick, and the drying speed is slowed down, which tends to cause dirt or adhesion on the back side of the printed matter. It is also easy to cause the paper to be caught in the ink roller in the printing of the flat paper.
(5) The viscosity of the ink is too small, the fluidity is increased, and the appearance is characterized by a large dilution of the ink. In lithographic offset printing , ink emulsification is likely to occur, resulting in dirty prints.
(6) The ink with too small viscosity tends to spread on the paper, resulting in a large area of ​​the print, a decrease in sharpness, and a reduction in the degree of firmness of the bond after drying the film and the surface of the substrate and the gloss of the print.
(7) When the viscosity of the ink is too small, it is often impossible to transfer the particles with larger particles in the ink, so that the pigment particles are gradually deposited on the ink roller, the blanket or the printing plate to form a stacking phenomenon.
Mascara is a cosmetic that is applied to the eyelashes and belongs to make-up cosmetics. Its main function is to color the eyelashes, make the cleansing look thick, long, curly, etc., make the shape of the eyelashes look neat and beautiful, and enhance the charm of the eyes.
Product classification editing Voice
Mascara or mascara is generally divided into two categories, water-proof and water-resistant.
1. Waterproof mascara
It is mainly wax-based, and the pigment is dispersed in a system containing volatile branched hydrocarbons, volatile polydimethylsiloxane, etc., when removing makeup, oily Makeup Remover products are required.
2. Water-resistant mascara
Mainly a system based on stearic acid or oleic acid triethanolamine and soap base. This type of formula has good water resistance, feels soft when applied to the eyelashes, is easy to remove makeup, and is less likely to cause eye irritation. Wash with water, or use ordinary cleansing to remove makeup.
In recent years, modern anhydrous gel-type formulations have significantly replaced waterproof emulsion formulations. Propose a third type of formula: waterproof-washable mascras or thermosensitive mascras. The use of a warm water-soluble film-forming agent is better than improved water-resistant mascara. Unlike waterproof mascara, it can be removed with water. If necessary, it can be cleaned with ordinary cleansing instead of oily makeup remover.
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