Infiltration of ink during printing (2)

If the printing pressure is high and therefore not negligible, the formula (7-3) should be corrected. The printing pressure at this time is p penetration depth h2, pressure difference is ΔP2, and there is Pr under high printing pressure. 》2rΥ·cosθ, the above formula can be approximated writing

(7-4)

The formula (7-4) is called Olsson formula. The formula shows that under high printing pressure, the paper is invariable, and the ink penetrates under the double action of paper capillary force and printing pressure. The role is dominant. At this time, the penetration depth of the ink is not only proportional to the square root of the penetration time, but also inversely proportional to the square root of the viscosity of the ink, and is proportional to the square root of the printing pressure.

The conclusion of Olson's formula has been confirmed by experiments. The relationship between the penetration depth (μm) and the imprinting time shown in Fig. 7-8 is that the A ink with a viscosity of 5.3 Pa·s and the B ink with a viscosity of 2.6 Pa·s at a printing pressure of 2.8×10 4 Pa, change the pressure Printed on time, measured data for impression time and penetration depth, and fitted curve. The curve shows that the depth of ink penetration is proportional to the square root of the stamping time.

The relationship between the ink penetration depth (μm) and the viscosity of the ink shown in Figs. 7-9 is 0.04s for the imprinting time and 1.4x104Pa for the printing pressure. Different viscosity inks were used for printing, and the obtained experimental data were fitted with curves. The curve shows that the depth of penetration of the ink into the paper is inversely proportional to the square root of the viscosity of the ink.

Figure 7-10 shows the relationship between ink penetration depth and printing pressure. The curve shows that the penetration depth of the ink and the square root of the printing pressure are basically linear.