Causes and Solutions of Curl after Printing Thin Paper

In the process of cutting thin paper sheets (such as dictionary sheets, etc.), curling and warping of printed sheets frequently occur, which affects the progress and quality of the cutting process. The main reason for the analysis is that the water content of the printed sheets is caused by the unbalanced temperature and humidity of the environment. The following methods can be adopted to solve the problems.

Dehumidification

Because the inside of the printed sheet is lower than the moisture content in the air, the radial section after cutting must absorb moisture quickly to achieve a corresponding balance. Therefore, the moisture in the indoor air should be properly reduced to avoid curling in the radial section after cutting. Solution: Use the dehumidification function of the air conditioner to remove excess moisture from the indoor air and effectively achieve dehumidification. The relative humidity is 50% RH, the temperature is 20 ~ 29 °C, the temperature and humidity meet the standard requirements, and the printed sheets are not easily curled and deformed.

2 page method

If curling occurs after the paper is printed, it can be solved by using the stencil method. The printed sheets were turned over first, and the curled printed sheets were punched on many fold lines by hand by means of a manual “crepe paper” method. The support force generated between the fold line and the fold line was used to forcibly change the curved printed sheets to make them relatively flat.

3. Paper method

The paper-drying method uses a paper-hanging machine to blow or dry the cut or uncut white paper, so that the internal humidity and air humidity of the paper are relatively balanced, and it is not easy to be deformed during printing and post-press processing. This can improve the printing quality. , also to the binding process to reduce a lot of trouble.

In addition, in order to ensure a reasonable amount of moisture inside the paper (about 5%), should also pay attention to the stacking position of the paper, not against the wall, by the window, by the heating (winter), but not on the open air, so as not to be too dry, damage the paper a reasonable moisture , causing paper warpage inequality.