10. What are the effects of fillers on paper properties?
A: adding fillers to the printing paper can improve the printability of the paper, such as increasing the whiteness, smoothness, opacity, and stiffness of the paper. Improve the affinity, softness, and stability of paper to ink, which is helpful to improve the quality of printed matter. Of course, too much filler in the paper also brings some adverse effects, mainly for the reduction of paper strength and sizing effect. In printing, it is easy to drop powder and hair, and the filler particles will be transferred to the printing plate and blanket, resulting in paste plate and other phenomena. Due to the friction effect of filler, the printing plate will be worn, but the addition of precipitated calcium carbonate (PCC) can make the printing plate smooth Wear plates to a minimum (currently used by Jindong).
11. What is the opacity of paper?
A: opacity refers to the opacity of paper. The opacity of paper depends on the light scattering ability of paper, the number of light scattering interfaces inside the paper (i.e. the number of independent particles inside), and the refractive index difference of the scattering interface. The more light scattering interfaces, the greater the refractive index difference between scattering interfaces, the greater the light scattering ability, and the higher the opacity of the paper.
12. How does filler affect the opacity of paper?
A: paper without filler is composed of fiber and air. Air exists in the pores between the fibers. Because the refractive index of the fiber and air is different when the light beam irradiates the paper surface, part of the light scatters on the interface between the fiber and air, giving the paper a certain (lower) opacity, which is reflected in the printing, and the main performance is easy to pass through. After adding fillers with a refractive index higher than cellulose into the paper, the number of light scattering interfaces in the paper increases, that is, there are three different interfaces between fiber and air, between filler and fiber, and between filler and air. Among these three interfaces, the difference of refractive index between filler and air is larger. As a result, the light scattering at the interface between the filler and the light gets the maximum opacity.
13. How can fillers improve the smoothness of the paper surface?
A: the network formed by interweaving fibers always has a large number of pores and surface irregularities. Adding fine particle filler can improve the softness and plasticity of the paper, and can carry out better calendering treatment, so as to improve the smoothness of the paper after calendering.
14. How does filler affect paper strength?
A: the combination between fibers is the basis of paper strength. The addition of fillers reduces the combination between fibers, so adding a large number of fillers will significantly reduce the paper strength. Among them, the tensile strength, folding strength, and bursting strength decrease greatly, while the tear strength decreases slightly. The amount of filler used is limited to a certain extent.