As one of the main papers used by printing plants, coated paper has strict technical requirements in practical applications.
First of all, the raw materials. Coated paper is mainly composed of coated paper and coating. Coated paper needs to be uniform in thickness, small in elasticity, high in strength and good in water resistance. The paper surface should not have spots, wrinkles, holes and other problems. The coating is composed of high-quality white pigments such as kaolin and barium sulfate, adhesives such as polyvinyl alcohol and casein, and auxiliary additives.
In the production process, before each batch of coated paper is put into use, its smoothness, pH, absorbency, dryness, elasticity and surface bonding strength and other printing suitability should be tested and analyzed, and then corresponding process measures should be taken according to the characteristics of the paper, such as adjusting the viscosity, fluidity, dryness and anti-sticking measures of the ink. When printing, it is necessary to grasp the padding technology and printing pressure adjustment, the pressure should be uniform and appropriate, and neutral and hard materials are generally used as lining. For example, when printing trademarks and packaging products, light colors are often used as the base color. When mixing the base color ink, heat-resistant and light-resistant inks should be used. The diluent is best mixed with glossy paste.
In addition, because the surface of coated paper is smooth and its ink absorption capacity is poor, it is necessary to "print with deep ink and thin ink" when printing large-format solid plates. No. 19 resin oil can be used as the ink oil for printing the first color. Powder removal and black shadows on the printed surface are prone to occur during the printing process. The plate mounting process and ink viscosity should be checked. Anti-sticking technology can also be adopted, such as adding no more than 4% of anti-sticking agent to prevent ink emulsification and other problems.
Coated paper of different quality grades (A, B, and C grades) is widely used in the market, from exquisite picture albums, book covers to various packaging and labels, and its various technical requirements also guarantee high-quality printing effects.