The coating process is often used in the process of trademark making and packaging. But in the actual production, due to improper operation or other reasons, the product will often wrinkle, blister, curl, and other quality problems after coating. However, the blistering phenomenon often occurs after a period of time, which affects the product quality, even causes scrap in serious cases. Therefore, in production, operators must operate correctly, grasp all links, and make the products meet the quality requirements. The following views on the quality control of coated products are discussed.
Control of products to be constructed
1. the products to be constructed must be straight and straight. The uneven paper with the "Lotus edge" and "tight edge" phenomenon should be treated“ The paper with the edge of lotus leaf can be baked and the paper with a tight edge can be hung and dried.
2. it is necessary to cover the film after the imprinting is dry, otherwise blistering or pulling will occur.
3. spray powder as little as possible during printing, otherwise, it will cause an air bubble at the powder stacking place. Before coating, the powder shall be treated, and the powder can be hung and dried if the number of prints is too many, and the ones with less printing can be wiped manually.
4. when coating, pay attention to the direction of the paper wire, especially thick paper, to reduce the curling phenomenon of paper due to rolling and stretching.
Control of operation process
1. the thickness of glue should be appropriate. Too thick to produce curl, and affect gloss; Too thin to have enough viscosity, and even bubble. It should be adjusted according to the product. Generally, the copper plate paper should be thin and the offset paper should be thick.
2. the pressure shall be adjusted according to the product conditions. Generally, the pressure of copperplate paper should be smaller than that of offset paper, and that of thin paper is smaller than that of thick paper.
3. the temperature is generally controlled as 40-60 ℃. The too high temperature will make paper and film deformation, resulting in product curl, but also can not be too low, otherwise will cause viscosity insufficient. The temperature of the copper plate paper should be slightly lower than that of the offset paper.
4. the film tension should be appropriate. Generally, it is appropriate to maintain normal operation and not lag behind. Too tight to make the product curl, too loose will wrinkle.
Control of temperature and humidity in the workshop
1. in order to ensure the quality of products, the temperature of the film coating workshop should be suitable for printing workshops, and should not be too high or too low.
2. humidity is generally smaller than that of a printing workshop. Humidity is too general to cause product deformation or even fold, and curl will be caused after the product is processed. Too low humidity will cause static electricity in the coating process, which will affect the subsequent process.
Control of raw materials
According to the product property, paper thickness, quality requirements, and so on, the raw materials are selected correctly. Generally, the thin paper should be a thin film, so as to avoid curling. The film with better gloss should be selected for the products with high requirements. Glue shall be transparent and free of precipitation. The use of pre-coating is recommended to reduce the damage to human health.