In the paper printing process, we often meet with such a phenomenon: sometimes in printed the lateral size fluctuation appeared deviation, error generally less than a mm, but sometimes but to 3 ~ 4 mm. And the farther apart the unit, transverse overprint of the error. In addition, sometimes misregister problem as well as in the whole layout of the diagonal, a head of overprint in good condition, the other end has a lot of error. Through many years of practice, a line workers found that the problem is mainly due to paper moisture absorption and heating and drying two completely opposite process caused by the joint action.
Gravure machine of the printing speed is very fast, drying temperature and higher temperature, at the same time the paper basic consistent, so how would paper moisture absorption?
Paper moisture absorption has two aspects, one is in the book part, web in the book, in the part of the paper, paper positive coating can block some water into the paper, and on the other side is relatively more moisture, in the ordinary circumstances, the paper will increase 2% ~ 3% of the water. The second is now advocate of green printing, water-based ink are gradually applied in gravure, including water light oil. If large printing water-based ink, paper surface due to moisture temporary deformation, after high temperature drying, dry part will occur contraction and make paper transverse dimension. If the oven heating temperature is higher, the moisture in the paper is the more volatile, paper deformation shrinkage of the greater the amplitude, the printing color can appear when misregister phenomenon. In addition, the web in the moisture content of paper is even, if roll around the middle of the water content, not consistent, also can appear such problem.
Solve the thin paper printing collapsible method is appropriate to improve the printing speed, and try to reduce the heating temperature, reduce unnecessary hot air drying, with printing print not reverse sticky, not fade as the prerequisite. In addition, the paper tension big also can make paper width on the paper process change and cause transverse misregister.
This is paper printing collapsible when general solution, but specific problems should be specific analysis, collapsible and printing of each link, workshop of the surrounding environment and the operation of the workers of water quality is closely related to such factors. (Gold Printing Group) |
