Printing properties of paper and commonly used printing paper
Printing properties of paper and methods for measuring the ink absorption of commonly used printed paper sheets
Print is a combination of paper and ink. The basic process of printing is the combination of paper and ink. How to adapt the nature of the ink and the technical measures to the properties of the paper is the basic link for maintaining the quality and improving the quality of the printed product. Obviously, to solve this problem, we must have a full understanding of the paper that is commonly used in the nature of paper.
The use of paper is extensive; there are many different types of applications, and different uses have different requirements for the properties of K. Grasses are used for printing, and due to various printing methods and process characteristics, they also have different requirements for strong properties. For example, letterpress printing requires that the paper has a high degree of sizing (water repellency). The paper's ink-absorbing performance is moderate and should not be too high. The material particles are wrapped and dry, and only a small part is absorbed by the paper to accelerate the operation. If the paper has a strong absorption of ink, the binder in the ink is inhaled by the paper in large quantities, and although the drying of the imprint can be accelerated, the imprinting is liable to result in a poor print and poor transparency. as a result of. Therefore, offset printing does not require strong ink absorption performance.
The general letterpress printing has strong absorptive capacity for paper, because the oil base of the printing of books and books is made of non-drying oil. It is totally dependent on the paper to absorb the ink in the ink and dry, especially at high speed. The outline of the printing machine absorbs the quick-drying material in the ink in a short period of time. Only the pigment and the resin (such as asphalt) are left on the surface of the paper and dried, otherwise the reversed surface or fold will be blurred in writing, and the back surface will be dirty. unpleasant sight. Therefore, the printing of books and magazines is printed on newsprint paper with strong ink absorption.
The ink absorption of paper is the total response of the surface properties of the fibers, the interweaving condition of the fibers, the properties and content of the rubber. The essence of Tuen is the capillary adsorption of the binder in the ink by the tiny gaps between the fibers themselves and the fibers. Because the surface of the fiber pusher is not absolutely smooth, it has a lot of western-like shape. These micro-holes can adsorb the most suitable binder, and the more micro-holes, the greater the absorption. Shorter than full deuteration
The juveniles are not sufficiently intertwined with each other, and there are many gaps in the fiber and the males. It often plays a major role in the absorption of the binder in the ink ‘. Some fillers, such as clay, have a strong absorption of oil. When its stock in paper cannot fully fill the gap between fibers, it can increase the porosity of the paper and enhance the ink absorption capacity of the paper. . The proper presence of rubber can increase the lubricity of the ink on the surface of the paper, and when its stock is not sufficient to completely close the gaps of the fibers, it can also improve the ink absorption ability of the paper. However, after calendering, the corresponding ink-reducing ability of the bottom paper must be reduced. The relationship between ink absorption and product quality depends on strong ink absorption to adjust ink properties and dry oil addition and discharge. For example, paper with strong ink absorbency can reduce the amount of dry oil. , You can also get a satisfactory dry blot. This is when printing with newsprint (reporter); dry oil can be added to offset paper
Less important reasons. The ink absorbency of paper is more closely related to printing such as printing of version w. If the ink absorption of coated paper is too large, it often leads to phenomena such as “powdering” and dim light, which seriously affects the quality of the product. Therefore, the paper is used. When printing, in order to reduce the absorption of ink in the ink is largely absorbed by the paper, it must increase the viscosity of the ink, to speed up the imprinting and drying to adapt to other methods. If the ink receptivity of the reprinted version is too bad, the paper may easily cause bad impressions such as slow-drying of the imprint and sticking on the back side. Therefore, it is of great technical significance to measure the rough ink absorption before printing and to grasp the ink absorption performance of the paper.
Determination of the absorbency of paper The paper is planted into paper 6 cm wide and 20 cm long, placed on a long box of words or wood, and the box is at a 30-degree angle of inclination to the table top. The tube can hold 25 ml of dripping tube with xylene (or add one percent of asphalt) for titration, and the bottom of the burette is about 6 cm from the surface of the paper.
When a drop of xylene solution is applied to the surface of the paper while being marked with a code, the time required for the paper to be completely absorbed by the paper is the ink absorbency of the paper. It takes less time to absorb large paper, and vice versa. The general newsprint is about 10 seconds, and the offset is about 20 seconds. For coated paper, ink absorption is suitable for 30-.60 seconds. Too much ink absorption (less than 30 seconds) tends to cause chalking; ink absorption is too small (greater than 60 seconds) to cause quits.
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