At the moment of imprinting by the printing press, the ink transferred to the surface of the paper is subjected to the printing pressure, and part of the ink will be pressed into the pores on the surface of the paper. From the time the paper leaves the embossing area until the ink is completely dry, the ink is mainly absorbed by the capillary force of the paper. During the ink drying process, the ink binder that penetrates into the pores of the paper solidifies, forming a mechanical anchoring effect, thereby greatly improving the ink adhesion. Therefore, the porous structure of paper is the main factor affecting ink adhesion. With the development of papermaking technology, coated paper and swelling high-gloss photo paper have appeared one after another. The papermaking process improves the smoothness of the paper surface and reduces the porosity of the paper surface. Therefore, the chemical action of the surface coating has an increasing influence on the ink adhesion.
Experimental instruments : printability Tester, QFH paint film cross-cut Tester, Forced Air Drying Oven, permanent magnet DC motor and electric heating constant temperature Water Bath.
step
Add starch and water to prepare starch milk with a mass fraction of 40%, put it into a round bottom flask with a stirrer and a temperature control device, adjust the pH value with 3% sodium hydroxide, heat, and the temperature rises to a certain level value, add sodium hypochlorite, keep constant temperature for reaction, react for a certain period of time, neutralize with hydrochloric acid with a mass fraction of 3%, add sodium sulfite at the same time to terminate the reaction, then filter, wash with water, dry the filter cake, pulverize to obtain oxidized starch, dissolve to obtain Oxidized starch solution. Then heat and dissolve CMC, PAM and PVA powder respectively, and prepare corresponding solutions [5].
The prepared various surface sizing agents were evenly coated on the glass substrate, and then placed in a Forced Air Drying Oven to dry for a period of time to form an ink film. After the drying is complete, use the IG T printability Tester to print the same ink on the sizing agent, and then place it in the Forced Air Drying Oven for drying.
The method of identifying the ink adhesion is to use the QFH paint film cross-cutting instrument, according to the provisions of GB/T 9286-1998, use the cross-cut method to cut the cross-cut at 3 different positions on the sample plate, apply adhesive tape on the top of the grid to flatten, After affixing the adhesive tape for 5 min, hold the dangling end of the adhesive tape and tear off the adhesive tape at an angle of 60° as far as possible.
