Influence of paper moisture change on printing quality

Update:27 Apr 2019
Summary:

Printing suitability is reflected in the moisture of th […]

Printing suitability is reflected in the moisture of the paper, and it is generally required to be as consistent as possible with the relative humidity of the production environment. All kinds of paperboards above 200g/m2 are multi-layer composite papermaking in the papermaking process, and according to the requirements of their production process, many manufacturers cut and seal the paper in time after the paper is rewinded from the paper machine. Accurate delivery at any time. Due to the process requirements of the multilayer composite, the water content of the paperboard is generally about 5% higher than that of the plain paper. Although the high water content of the paper is advantageous for printing, if it is stored and used badly, it will bring a lot of trouble to the printing production. If the package is damaged, the local humidity of the paper in the bag changes, so that the paper is wavy, tightly edged, and there is a phenomenon of high side and low side; paper feeding is difficult during printing, ink and water balance is difficult to grasp, and humidity changes will cause the paper to expand and contract, causing the paper to expand and contract. Multi-color overprinting is not allowed, and the back mouth corners and other quality defects; especially in the next process, there are die-cutting products, and the paper stretching will cause problems such as irregular mold making and inaccurate die-cutting dimensions. Therefore, to treat 200g/m2 or more of color box wrapping paper, the following two points should be achieved in the specific production practice:
1. Scientifically and reasonably store and store paper. In view of the uniqueness of the paperboard, in order to prevent the paperboard from dehumidifying or absorbing moisture, the paper adapts to the change of the paper. In the transportation and storage of the paper, the integrity of the product packaging should be paid great attention to prevent the packaging from being damaged due to improper transportation and operation. In the storage, it is necessary to pay attention to ventilation, and to avoid light and shelter from the wind. The temperature is controlled at 15-25 °C, and the relative humidity is 40%-65%. The stacking of paper should be classified according to the paper production date, product category and production address. The paper should be fed sequentially according to the date of production, and try to provide a more stable paper moisture adaptability to the next process.
2. Effectively control the humidity change of the paper. If it is necessary to properly keep and reasonably arrange the use before cutting, how should we take measures to prevent paper size changes caused by temperature and humidity changes after cutting? First of all, we must be scientific and reasonable in production control, and paper strives to achieve With the printing, it is best to master the paper for one hour before printing. The large quantity can not be opened and cut all at once. It should be cut according to the printing speed and progress, and the cut paper is best. It is better to use a plastic cover with better sealing performance to minimize the time of direct contact with air, especially when multi-color products are printed on single or two-color machines. Not only the white paper but also the same method should be used after each color is printed to prevent the multi-color overprinting caused by the paper expansion and contraction caused by the humidity change, and ensure the quality of the printed product.