In April 2002, the fifth edition of "China's National Apparel and Printing Weekly" No. 2167 published a paper entitled "Because of Ink Thickness Adjustment" (hereinafter referred to as "Mian"). The author of the article is rich in practical experience and does provide useful experience. However, some of the references to ink performance in this article are incorrect. Here are some basic knowledge and concepts of ink performance. Please provide some insights and understandings for your opinions.
First, the relationship between the viscosity of ink and the thickness of the black layer "Ink" text said: "Increase in the thickness of the ink layer, the viscosity is also increased accordingly, the ink's mobility is small." Here the ink viscosity, fluidity. So, what is the viscosity of the ink?
Viscosity is a physical measure of ink performance. It is defined as a measure of the ability of the inter-particle interactions to hinder their relative motion, and viscosity is a measure of the cohesion of the ink. Viscosity units are "poise," "centimeters," or "pa.s. seconds," and "mPa.s.seconds."
Ink viscosity is usually measured with a "rotating viscometer" (Emila viscometer), a "drop bar viscometer" (Laray viscometer), and a "parallel plate viscometer." It can also be measured with bubble viscometer, capillary viscometer, falling ball viscometer, cone-plate viscometer and other instruments. It is worth noting that the amount of sample ink used when measuring the viscosity is strictly limited. Using a rotary viscometer, the ink is placed in a measuring barrel. Using a drop stick viscometer, the ink was placed inside a thick-walled tube. Using a parallel plate viscometer, the amount of ink dropped on the glass plate was 0, 5 cm 3 . In other words, the viscosity is a unit of quantity, and it is a measure based on the unit physical quantity, not an arbitrary variable.
When the ink layer thickness changes, does the viscosity change for the same ink? No! What changes here is the total adhesion of the ink, not the viscosity. Imagine an ink that has a viscosity when we use it for one kilogram, another viscosity when we use it for 0.5 kilograms, and a new one when it takes 0.1 kilograms. The viscosity; what is the significance of that public measurement of its viscosity?
Here again relates to another physical quantity of ink - viscous. Macroscopically, "viscosity" and "stickiness" represent the same type of performance. But they are not the same thing. Viscosity is a measure of the resistance to resistance when the ink is fractured and separated. The viscosity of the ink can also be determined using special instruments. But it is not dimensioned.
Fluidity also has a well-defined definition: the ability of an ink to expand its diameter under the influence of pressure. The fluidity can be measured with a flow meter.
The ink is a non-Newtonian fluid. Its movement is much more complicated than Newtonian fluid. Viscosity is not only related to its own structural components, but also related to temperature. The fluidity is not only related to its own structural composition and temperature, but also related to the thixotropy of the ink.
Color Fine Print Solid Density General Print Solid Density Yellow (Y) 0.85~1.15 0.80~ 1.10
Magenta (M) 1.25 to 1.55 1.15 to 1.45
Blue (C) 1.30 to 1.60 1.25 to 1.45
Black (BK) 1.40 to 1.80 1.20 to 1.60
Overcoat color 1.50 or more and 1.30 or more In general, viscosity and fluidity change in the opposite direction, that is, the greater the viscosity, the lower the fluidity, the smaller the viscosity, and the greater the fluidity. But they are not inversely proportional. For example, when corn flour is added to the ink, the viscosity is reduced, and the fluidity does not increase, but decreases.
Second, the relationship between ink depth and ink layer thickness "Ink" text said: "The printing of dark ink, the amount of ink can be appropriately thin. Because dark ink hiding power is relatively strong, not easy to produce the bottom of the flowers."
Ink thickness is a very important issue, but also a very sensitive issue. However, it is not related to ink color. For the continuous adjustment of the manuscript is a printed matter, in the People's Republic of China industry standard "CY/5-91 "Plain print quality requirements and inspection methods,"" has a clear provision. Item 4.1.1 of the standard lists "Table 1 density range":
The density on the ground here represents a thick layer of ink. Because if there is no defined ink layer thickness, there is no accurate neutral gray balance and there is no correct color reproduction. (To be continued)