[Chinese Packaging Network News] Coated paper is one of the fastest growing varieties in China's paper industry in the past 10 years. Coated paper is used as a printing substrate, and it is a higher product in the category of culture printing paper. It is a paper made by coating and finishing the printing base paper. In the printing of coated paper, a deep understanding of the printability of coated paper, especially the research on the adaptation of the printability of coated paper, will have extraordinary practical significance. It can be divided into coated white paper and gray Coated paper and so on.
In recent years, low-quantitative coated papers that have arisen overseas have been attracted to commercial printing, publishing and printing users due to their low basis weight (total quantification not exceeding 60g), low cost, and good printing performance. Printing for magazines, newspaper ad inserts, supermarket catalogs, etc.
In the past 10 years, the annual increase rate of the use of coated paper and machine slurry in China has been 18.8% and 25%, respectively. It is not difficult to estimate, with the succession of China's economic succession mediation, the further improvement of people's living standards, the use of coated paper in China will rise rapidly.
First, the basic situation of coated paper
The coated paper is coated with a layer of coating liquid with pigments, adhesives, tackifiers, fluorescent agents, lubricants and other rescue solvents as the primary factors on the appearance of the base paper, and is then dried to hold the rewards and punishments, which is in terms of color reproduction. With excellent performance.
Pigment coated paper is the most stressful type of coated paper. The pigment-coated paper is mainly composed of white pigments such as kaolin, calcium carbonate, barium sulfate and titanium dioxide, plus all kinds of adhesives and coatings formulated with various types of chemical rescue agents according to necessity, and are evenly coated in a certain amount. Made of cardboard. Offset printing coated paper, commonly known as copper paper. The name of the copperplate paper has been long-standing. The material used to build the letterpress version of the original version was heavy metal copper. This kind of printing plate is particularly suitable for printing such coated paper, so it is called copperplate paper. This type of paper is a higher printing paper made by coating and finishing the base paper. Offset printing coated paper is used to print all kinds of high-level prints, such as calendars, pictorials, pictures, illustrations, higher grades, product imitations, etc.
Second, the printability of coated paper
The printability of paper includes both the homework applicability and quality applicability. Homework applicability primarily affects printing utility, and quality appraisal primarily affects printing. As far as the suitability of papers is concerned, the paper's tensile strength, toughness, flatness, and deformability are closely related to its closeness. There are paper whiteness, opacity, emolliency, appearance strength, dimensional invariability, and ink receptivity that are closely related to quality. The printability of paper is customarily referred to as narrow printability.
Compressibility
When the paper is subjected to certain pressure, it will be slightly compressed. After the loss of external force, the degree of recovery of the paper gauge is called compressibility. Compressibility is related to the small pressure. Paper compression is particularly stressful on printing. Due to the printing, the paper is subjected to the necessary pressure to transfer the ink from the printing plate to the paper. Compressible paper, when the printing pressurization is appropriate, can make the graphic and paper of the printing plate have abundance of excellent elasticity, so that the graphic on the plate can be clearly transferred to the paper. . Because of the presence of the coating, the coated paper is as small as the compressibility. The thicker the coating, the lower the compressibility. Under the circumstances, the coated paper with a large amount of coating has poor printability. Low coated paper due to low coating (applying 6g/O per side), and the base paper contains machine pulp with good compressibility (any ratio ≥ 25%), plus the use of soft calendering finish, compressibility Coated paper is good, so its printing performance is good. In addition, the good compressibility of paper can also reduce the need for smoothness of the paper and flatness of the appearance of the text.
2. Appearance strength
The appearance strength of paper is a tight printability index. It refers to the degree of connection between the paper fiber structure, filler and rubber compound, and it selects the appearance of the paper in the printing of its anti-wear, resistance to powder and anti-fluff means.
For coated paper, the coating particles must adhere well to each other, the coating and the paper base require strong adhesion, and the paper-based fibers should have sufficient contact strength. Otherwise, when the paper responds to the printing pressure under the printing pressure, and the ink film on the plate fluctuates at a reasonably fast rate, the ink film will peel off the coating particles and the small fibers, giving birth to the so-called signs of hair loss and powder loss. Paste version. In offset printing coated paper, due to the higher viscosity of the imparted offset ink, there are signs of powder loss and hair loss.