The Relationship between the Thickness and Density of Packaged Printing Inks (2)

2 The relationship between ink layer thickness and ink supply

2.1 Experimental Design

When coloring samples on an IGT-C1 printability tester, set the amount of ink supplied to the ink-distributing unit to x (ml) with a precision ink refill (minimum scale of 0.1 ml) before printing and transfer it to paper after printing. The thickness of the ink film is d, and the unit is micrometer (μm). In order to obtain the relationship between ink supply and thickness, two experimental protocols are usually available.

Solution 1: Before printing, measure the density of the ink with a precision ink injector and an electronic balance. Measure the weight of the spline before and after printing. The difference Δm is accurate to 0.1 mg. Then measure the area on the strip. S, accurate to 1mm2. Substituting the following formula (4) gives the ink film thickness d (μm).

Option 2: First measure the density of the ink, and then weigh the quality of the printing plate before and after printing respectively. The difference AM is accurate to 0.1mg and the area S of the printing area is measured. Substitute Formula (5) to find the thickness.

Here, it is assumed that the reduced amount of ink on the printing plate is equal to the amount of ink transferred to the spline.

The use of Tianshi brand offset bright fast dry red ink (R) and transparent medium yellow ink (Y) in a mass ratio of 1:1 mixing, in 150g copper plate paper, according to the above two kinds of programs were compared experiments, the experimental data is drawn The curve is shown in Figure 1.

It can be seen from the curve in Fig. 1 that the results of the experiments made with Option 1 and Option 2 are almost the same, and the resulting curves are almost coincident. Therefore, both Scheme 1 and Scheme 2 can be used as a reasonable experimental scheme for measuring ink thickness. However, Option 1 weighs the weight before and after the spline is printed. Since the weight of the paper's squat body is significantly affected by the temperature and humidity of the measurement environment, accurate measurements must be made in a constant-temperature, constant-humidity room. Therefore, the following experiments were conducted using the method of Scheme 2.

2.2 Relationship between ink layer thickness and ink supply

The 150g coated paper is mixed with a red 1:1 mass ratio of red ink R (TGS-148) and yellow ink Y (TGS-239) and red ink R (TGS-148) and green ink C (TGS-318), respectively The experiment of increasing the ink supply from 0.1 to 1.1 ml was sequentially performed.

According to the data, the curves of the ink supply volume and the ink layer thickness transferred to the paper are plotted, as shown in FIG. 2 and FIG. 3 .

The relationship between the thickness d of the ink film and the ink supply amount x is called an ink transfer curve. The ideal ink transfer curve shows that regardless of the ink supply, the same amount of ink is transferred to the surface of the substrate; the actual ink thickness transferred to the spline is not strictly linear with the amount of ink supplied. Change, but slightly biased.

As can be seen from the figure, the ink film thickness d transferred to the surface of the spline varies with the amount x of ink supplied to the printing disc. 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; the ink is printed on the printing plate As the amount increases, so does the amount of ink transfer.

The experimental results show that two different inks, R+G (1:1) and R+Y (1:1), have a direct proportional relationship between ink supply and ink thickness during the printing process.