With the increasing demand for coated paper printed matter in the printing market, modern printing technology also puts forward higher requirements on the types of coated paper and various performance indicators. Therefore, to be familiar with various types of coated paper and the impact of its properties on the quality of printing has become a must-learn before purchasing coated paper. A wide variety of coated paper 1. Mirror coated paper / cardboard (cellophane / cardboard) After the paper is coated on one side, it is finished and calendered by a cast steel roll. The effect is like a mirror-like bright and smooth high-grade special coated paper. The paper base is strong, the paper surface is white, and the gloss is bright, which is especially suitable for high-color images with fine dots. The stiffness of the paper is better than that of special-grade coated paper, and it is slightly waterproof. 2. Double-sided coated paper/cardboard The paper is made by double-sided coating and calendering. The surface is smooth and bright, the whiteness is very good, the ink absorption is fast, the ink color reflection is high, and the two sides of the coating and calendering can be exquisite color printing. 3. Single-sided matte coated paper/cardboard A high-grade printed copperplate paper made from one side of the paper after being coated with a special powder surface and then evenly pressed. The surface of the paper presents a white powdery effect, which is quite delicate and smooth, non-reflective, and the ink color is stable and elegant after printing. 4. Single-sided coated paper/cardboard The paper is made by calendering after being coated on one side. The surface is smooth and bright, the whiteness is very good, the ink absorption is fast, the ink color reflection is high, the coated and calendered side can be exquisite color printing; the uncoated side can be monochromatic or color printing. 5. Micron paper The coated paper is made of double-sided offset paper with specific requirements as the base paper, coated on both sides in the machine, and then super calendered. Its market positioning is economical coated paper. 6. Double-sided matte coated paper/cardboard The high-quality printed copperplate paper is made by coating and pressing on both sides of the paper with a special powder surface evenly. The surface of the paper presents a white powdery effect, which is quite delicate and smooth, non-reflective, and the ink color is stable and elegant after printing. 7. Micro-coated coated paper A product between coated paper and light-coated paper, is now widely used in Europe. Its whiteness is close to that of coated paper. After printing on a matt surface, it will not reflect light, so it is easy to read. The surface of printed and non-printed paper has a strong contrast and is suitable for processing. It does not have bubbles, is easy to fold, easy to punch holes or fold dotted lines, and the price is more competitive than coated paper. 8. Wet Strength Coated Paper The base paper undergoes special treatment (adding wet strength agent, etc.) during the papermaking process. After soaking in water for 1 hour, the base paper can maintain a dry strength of more than 15%. After the paper is coated on one or both sides, it is pressed again. Light can be made into wet-strength coated paper. This kind of paper is especially suitable for printing maps and charts. The Influence of Coated Paper Properties on Printing Quality Paper is one of the five major elements in the printing process (printing plate, ink, fountain solution, printing material, printing machine). The performance of coated paper directly affects the speed of printing and the quality of printed products. It can also be said that the quality of coated paper Performance determines whether the printing process can proceed smoothly and whether high-quality prints can be obtained. 1. Surface strength of coated paper The surface strength of coated paper refers to the bonding strength between the coating particles on the surface of the coated paper and between the coating and the base paper. It is an important performance index of coated paper, which is usually expressed by the napping speed. When the surface strength of the coated paper is low, it is easy to shed hair and powder during the printing process. As the printing progresses, more and more paper wool and paper dust will accumulate on the printing plate, which will eventually lead to paste and affect the printing quality and printing operation. Therefore, improving the surface strength of coated paper is very necessary to ensure a good printing effect. 2. Moisture and temperature resistance of coated paper The moisture of the coated paper refers to the percentage of the weight of the moisture contained in the coated paper to the weight of the coated paper. With the development and progress of society, the printing industry has also developed by leaps and bounds. The emergence of commercial web printing presses has put forward new requirements for the temperature resistance and moisture content of coated paper for printing. If the moisture is improper and the temperature resistance is poor, the bubbling phenomenon of coated paper in printing will become a more serious and common problem in rotary printing. Due to the characteristics of high-speed printing of the rotary printing machine, generally up to 40,000 to 50,000 sheets per hour (and the general sheet-fed paper printing speed is less than 20,000 sheets/hour), and the direct folding is performed after the printing is dried. At such a high speed, in order to prevent printing abnormalities such as non-drying of the ink and smearing of the back, the printing ink needs to be dried quickly, and the most effective way to dry the ink quickly is to heat at high temperature, so in the structure of the rotary printing machine There is an oven to heat the coated paper after printing so that the ink can dry quickly. The quantitative moisture in the coated paper becomes water vapor when it is dried at a high temperature (the drying temperature is generally around 140°C), and the coated paper has a coating layer on one or both sides, and the coating is due to adhesion The effect of the agent and its crosslinking agent, although avoiding the phenomenon of lint and powder falling during the printing process, it is not good for the release of water vapor during the drying process of the printing ink; if the paper is at the same position on both sides of the paper, it happens to be full When printing and the amount of ink is large, the ink will completely cover the paper surface, which further prevents the water vapor from being released outwards, resulting in bubbling. In order to avoid blistering in printing, the following 3 points should be paid attention to when selecting and using coated paper: (1) Control the temperature of the coated paper printing workshop at 18～25℃, and keep the relative humidity at 50%～60%. (2) Choose coated paper with good temperature resistance. (3) Choose coated paper with moisture content between 6% and 8%. If the water content of coated paper is too high, the water vapor in the printed matter with coating and ink cannot be released quickly in a short time, which will cause bubbling; if the water content is too low, the paper is prone to static electricity and tends to It is brittle and hard, not conducive to printing; uneven water content will form tight edges, ruffles, curls, etc.
