The amount of ink in ink transfer and its measurement--ink transfer equation (below)

Second, the amount of ink and printability testing machine

For the determination of x and y at the printing site, the weight of the inked plate and the weight of the printed body must be weighed separately. The difference between the two is divided by the printing area x; the weight of the inked plate is weighed separately and remains after printing. The weight of the printing plate of the ink, the difference between the two divided by the printing area, can also weigh the weight of the paper (or other printing material) before and after printing, and the difference divided by the printing area yields y. In the experimental process, the full surface of the printing plate is full of ink, and the printing area is the area of ​​ink on the printing plate. The y is determined by the weighing method, the result is more accurate, but it is only applicable to the plate with lighter texture and smaller size; the method of weighing paper is used to determine y, and the result is not stable because of the influence of temperature and humidity in the measuring environment. accurate.

Laboratory tests for x and y are performed on a printability tester. The printability tester (also called printability tester) is a small-scale tester for simulating the printing process. At present, the domestic IGT-type and AIC-type printability testers are used more frequently in the country. The printability tester can do paper and ink printability experiments and simulate various printing methods. There are many experimental projects.

Figure 4-2 is a simplified schematic of the AIC 2-5 printability tester. The main components are a sector plate and two printing plates. The sector plate corresponds to the impression cylinder of the printing press. The printing plate corresponds to the printing plate. The paper is wrapped on a fan-shaped disk and the ink is coated on the printing disk. The amount of ink can be controlled. After the pressure is combined, the printing disk is in contact with the fan-shaped disk and the ink is transferred. The uniform printing speed range of this machine is 0.2~5 m/s; the maximum speed of accelerated printing can reach 7.0m/s. The printing time interval between two printing plates can be adjusted, and the adjustment range is 0.014~6s.

Simulated printing on the printability testing machine, measured the corresponding data, x, y can be calculated according to the following formula:

x(y/m2)=[Printing plate weight after printing (g) - Printing plate weight (g)]/Printing area (m2) (4-3)

y (g/m2) = [weight of printing plate after printing (g) - weight of printing plate after printing (g)]/printing area (m2) (4-4)

x (μm) = [printing plate weight after printing (g) - printing plate weight (g)]/[printing area (cm2) × ink specific gravity (g/cm3)] × 10-4 (4-5)

y (μm) = [weight of printing plate after ink (g) - weight of printing plate after printing (g)] / [printing area (cm2) × ink specific gravity (g/cm3)] × 10-4 (4-6)

The data listed in Table 4-1 is the measured results of the plate ink volume x and the transferred ink volume y.

Table 4-1 Experimental data for x and y

As can be seen from Table 4-1, the amount of ink y transferred to the surface of the paper varies with the amount x of ink supplied to the plate. When the ink on the printing plate is in contact with the uneven paper surface, if the amount of ink on the printing plate is too small, the contacted paper surface is insufficient to cover uniformly, so the ink transfer amount is small, and the printing plate is inked. As the amount increases, the area of ​​the paper surface that is in contact with the ink is gradually increased. Therefore, the ink transfer amount gradually increases.