In actual production, the control of ink drying speed is the most important means to prevent smearing on the back of the main factors influencing the imprinting dry with paper, ink and ink layer thickness, wetting liquid and emulsification degree, environmental temperature and humidity and the production technology, etc.
A. paper. Surface roughness, loose structure, small paper sizing degree, good absorbency, imprinting quick drying; After smooth paper into paper crib, the air is not easy to import paper pile bottom, influence the oxidative polymerization drying speed, paper low pH, high water content will delay the drying of printing ink.
B. the influence of auxiliary agent. When printing ink itself contains drier, in order to speed up the drying speed sometimes add to the water in the ink drier, but drier excess makes ink emulsification is serious, but is not conducive to dry. When paper appear hair phenomenon, tend to stick to join a certain amount of agent to reduce ink viscosity, however, to goo is not material, reduces imprinted ink layer drying speed.
C. wetting liquid and emulsion. The stronger the wetting liquid acid, ink drying speed is slower. Dry ink emulsification, also the slower, small width paper printing large format printer field background, smearing the easiest to appear in the paper on the back on both sides of the axial, solution as far as possible to use water blowing device or roll in a vase with piece of paper, the method of reducing water supply at the ends of the plate, reduce the ink emulsification value, so imprinted ink dry in a timely manner.
D. printing pressure, printing speed. Increase the printing pressure, printing ink can promote pressure infiltration; Reduce the printing speed, can increase the embossing, can play the role of prevention of smearing on the back.
E. the environment temperature and humidity. Ambient temperature is high, the chemical reaction speed, molecularly imprinted dry faster, in the summer, usually light quick-drying inks, can also quickly without drying oil dry, in winter, you will need to add some drier, therefore, workshop temperature and humidity control, for master molecularly imprinted drying speed is very important.
F. printed sheet pile method and spray powder. Printed products after stacking crib, air is very difficult to penetrate into the lower part of the paper crib, caused by a lack of oxygen, to transfer this part is hard to dry. Therefore, in order to prevent drying too slow and smearing on the back, in order to strengthen the management of semi-finished products after printing is very important. Printing is not easy to dry products, on the one hand, stacking is unfavorable and exorbitant. On the other hand, after the ink layer fixation, interval time, press gently shake to make breathable, adding ink and air contact, to speed up the ink dry. Widely used in sheet-fed offset printing powder to prevent the back rubbed against dirty, powder spraying is using powder support role, increase the distance between the printed sheet, is beneficial to air circulation, speed up the drying process.
(Gold Printing Group) |
