The influence of packaging offset printing on post-press lamination（2）

3. Add and release printing powder

In order to adapt to the high-speed printing of multi-color machines and prevent the backside of the paper from being smeared, packaging offset printing is often solved by powder spraying. The powder sprayed is mostly composed of cereal starch and natural suspended matter. These powder particles are coarse. If too much powder is sprayed during the printing process, these powder particles will float on the surface of the printed matter. When laminating, the adhesive will not be combined with the ink layer everywhere, which will seriously affect the quality of the laminating film. Therefore, the amount of powder sprayed must be strictly controlled during packaging offset printing. Under the premise of not sticking dirty, use the least amount of powder spraying.

4. The surface and inner layer of the printed matter are dry

Poor drying of the ink layer on the surface or the inner layer of the printed matter will cause great harm to the quality of the film and cause quality problems such as blistering and delamination. There are many factors that affect the drying of the surface ink layer of the printed matter, such as the type of ink, the amount of desiccant, the structure of the paper, the temperature and humidity of the workshop environment, and so on. Therefore, we must pay special attention to the dryness of the ink layer when printing. Strictly control the water and ink balance during printing, pay attention to the emulsification of the ink, and control the acid value of the fountain solution. At the same time, control the temperature and humidity of the workshop. Make the surface and inside of the packaging printed matter truly dry, so that the quality of the film can be guaranteed.

In short, in order to ensure the quality of packaging and printing products, we must not only consider the situation of the laminating process, but also from the beginning of printing, otherwise the quality of the previous process will affect the quality of the subsequent process. This concept should be remembered. It is necessary to establish the idea that the former process serves the latter process.