How much do you know about ink knowledge?

1.

The fluidity of ink includes viscosity, adhesion, viscoelasticity, yield value and thixotropy

①When the ink is poured from the container into the ink fountain, it is called good fluidity; on the contrary, it is worse than the coating online coatingol.

②When the ink is output from the ink fountain, it is called good fluidity if it is easy to ink; otherwise, it is poor

③ In the ink distribution, ink transfer and inking, the ones that are easy to spread, transfer, and transfer are called good fluidity; otherwise, it is poor

In the printing process, the correct control of the fluidity of the ink has important technological significance

2.

The flow phenomenon when the ink is output from the ink fountain is called the ink drop property

When the ink is output by the ink fountain roller, it is only affected by the external force of the ink fountain roller.

In the printing process, the ink drop property directly affects the ink supply per unit time and the thickness of the ink layer during the transfer and transfer process

3.
What is the transferability of ink?

After the ink is output by the ink roller, the flow phenomenon that appears is called the transferability of the ink
.

In the printing process, the thickness of the ink layer on the surface of the printing plate and its uniformity are realized by a series of ink rollers and uniform distribution.
Therefore, the quality of ink transfer is directly related to the distribution and distribution of ink volume.
And its smooth transfer in the whole process
.
Generally speaking, the process from the ink fountain to the ink on the printing plate mainly depends on the viscosity, stringiness and thixotropy of the ink itself
.
Under normal circumstances, when the stringiness and viscosity are appropriate, the ink exhibits better transferability, and the ink volume distribution is also better; when the stringiness and viscosity are too large, the transferability becomes worse, and the ink volume distribution also becomes worse; When the ink filament is too long, it will easily cause the ink flying phenomenon
.
 

4.
What is the transferability of ink?

When the ink is transferred and distributed (from the ink fountain, after complex transfer and distribution, until it smoothly transfers to the surface of the printed sheet to form an imprint), the flow phenomenon that appears is called ink transferability, which is the adaptability of the ink operation Subject
.

The transferability of ink can be understood from two aspects: on the one hand, the transfer of ink between ink transfer, ink distribution and inking roller; on the other hand, the ink transfer between the printing plate and the blanket, and between the blanket and the printing sheet.
Transfer
.
The former is mainly affected by inking and transferability, while the latter is also affected by printing conditions (such as printing model, printing speed, printing pressure, etc.
), blanket and paper
.
That is, the transferability of ink is shown in the entire process of ink transfer, distribution and ink layer separation (or split), which is of great significance to offset printing
.
The quality of ink transfer is mainly determined by the stringiness and viscosity of the ink.
In addition, it is also related to its wettability, viscosity, yield value, thixotropy, and surface tension
.

5.
What is the print quality suitability of printing ink?

After the ink is transferred to the surface of the printed sheet by a blanket at a certain printing speed and under a certain printing pressure, the fixing and drying speed of the ink film, as well as the color, gloss, fastness and resistance of the film after formation The various properties that guarantee the printing effect, such as sex, are collectively referred to as the print quality suitability of the ink
.
Mainly includes color, permeability, drying property, gloss, rub resistance and the like
.

 6.
What is the color printability of the ink?

In printing, the ink color of color or non-color prints is not based on the appearance and color properties of the ink as the judgment basis, but based on the ink film layer cured on the surface of the printed sheet
.
The color of the ink mainly depends on the color of the pigment used and the nature of the binder, while the color displayed by the ink film is closely related to the intensity and wavelength of the irradiated light, the photochemical properties and surface properties of the surface of the printing material, and the thickness of the ink layer.

.

The color of the ink used for the four-color (or three-color) color offset printing should theoretically be the complementary color of the color filter used when the original color is decomposed, but the three primary color inks actually used have impure coloring, dim brightness, and low saturation In addition, under different paper types and properties, the gray-balanced solid density value is different; the color displayed by the ink in the wet state and the dry state of the ink film is different during the printing process
.
Therefore, it is particularly important to select the appropriate printing ink to meet the color and printability of the ink.
This not only has practical technical significance for reproducing the tone and color of the original manuscript, but also is particularly important for displaying the artistic effect of the printed matter
.
In the current technical standards for ink products, the color has not yet listed numerical indicators, and only "standard samples" are used as the benchmark
.

 7.
How to determine the color of ink?

According to specific conditions and conditions, there are currently three methods for measuring ink color:

①Scratch method
.
Take a small amount of standard sample ink and sample ink and mix thoroughly, and place them on the standard sample paper (offset printing paper or offset printing coated paper) side by side, and scrape them into 3～5mm long strips from top to bottom with a squeegee.
Thin ink film layer, thick ink film layer is harvested after passing the black belt
.
Then, visually inspect the difference between the background color, face color and ink color of the standard sample and the sample ink layer above the black belt, and compare the color differences between them to make an evaluation
.

② Densitometer method
.
Place the solid density samples of the three primary color inks under the red, green, and blue-purple color filters of the color reflection densitometer, and measure their high, medium, and low optical density values ​​respectively, and then calculate them according to the prescribed calculation formula The hue error, gray scale and actual efficiency of the system
.

③ The color of ink can also be measured by roller coating method, printability tester, or colorimetric spectrophotometer
.

 8.
What is the permeability of ink?

Ink permeability refers to the permeability of the ink layer transferred on the surface of the printed sheet, and it characterizes the penetrating phenomenon and properties of the ink in the early stage of the drying process
.
In the offset printing process, the penetrating process of the ink (binder) includes two processes, namely, the instant rapid penetrating process that occurs at the moment of the printing pressure and the slow free penetrating process after the printing pressure disappears
.

In the offset printing process, the permeability of printing ink mainly depends on the nature of the binder itself, but also related to the printing pressure, printing speed and the type of paper used, surface properties (such as ink absorption, smoothness, etc.
)
.
Generally, the penetration of ink layer on paper shows different penetration properties and penetration rates due to different ink types and viscosity.
Generally, the permeability of oxidative polymerization conjunctival ink is lower than that of penetrating gel conjunctival ink
.

9.
What does ink permeability mean for printing?

The permeability of the ink is of great significance to the fixation and drying of the imprinted ink layer and the color reproduction, gloss and rub resistance of the ink layer after the conjunctivation
.
When the ink permeability and the ink absorbency of the paper are too strong, it is easy to cause chalking, print-through and other phenomena, which will significantly reduce the color, gloss and friction resistance of the imprinted ink film; when the ink permeability is too small, It will cause the back of the printed sheets to be dirty (or smeared), and in severe cases, the piles of printed sheets will stick to each other
.

 10.
How to measure ink permeability?

The permeability of the ink is usually measured with a permeability tester
.
The specific method is to print (or scratch-print) the test ink on a standard paper pattern, then cover the same standard paper pattern on its surface, and install it on the permeability tester, and roll it 5 seconds after printing (scratch-printing) To 1/3 of the full length of the sample; at 30 seconds, roll to 2/3; at 60 seconds, the entire sample is rolled
.
Take out the sample, examine its permeation phenomenon in different time, and judge its permeation property based on this
.