Pulping is closely related to the quality of paper. As the degree of pulping increases, various properties of the paper undergo corresponding and different changes. The curve rules of various physical property changes of the two types of pulp are similar, indicating that the effect of pulping on different fibers has a common rule, but there are slight differences with the different types of pulp. The slurry after pulping treatment needs to be formed through Polyester Forming Screen Forming Fabric. Its water filtration efficiency and the mesh structure of Polyester Forming Screen Forming Fabric need to be reasonably matched according to the degree of pulping. Only in this way can the quality of subsequent paper pages be guaranteed. High-quality Polyester Forming Screen Forming Fabric can better adapt to pastes of different pulping degrees, helping to improve the quality of paper sheet forming. Meanwhile, The flatness of the mesh surface of Polyester Forming Screen Forming Fabric will also cooperate with the fiber morphology after pulping, further optimizing the uniformity of the paper sheet Choosing the appropriate Polyester Forming Screen Forming Fabric is the key to connecting the pulping and molding processes.
(1) The relationship between fiber binding force and pulping
With the increase of pulping degree, the swelling and fineness of fibers increase, the specific surface area of fibers expands, more hydroxyl groups are released, promoting the hydrogen bond combination between fibers, and the binding force of fibers continuously rises. The improvement of this fiber bonding force will enable the fibers to interweave more closely when the paste is formed on the Polyester Forming Screen Forming Fabric, reducing the porosity of the paper sheet.
In the early stage of pulping, the curve of fiber binding force rises rapidly, indicating that the rate of fiber swelling and the growth of fine fibers is very fast. In the middle stage of pulping, the curve of fiber binding force gradually slows down, indicating that the surface area of the fibers has been fully exposed, and the growth rate of the fiber binding area has become increasingly slow. In the later stage of pulping, the curve of fiber bonding force gradually straightens out, indicating that the fibers have highly absorbed water, swelled and become fine fibers in the later stage of pulping. It is quite difficult to further increase the bonding area of the fibers, so the bonding force of the fibers reaches its peak. When the fiber bonding force reaches its peak, the demolding performance of Polyester Forming Screen Forming Fabric is crucial for maintaining the structural integrity of the paper sheet. High-quality Polyester Forming Screen Forming Fabric can prevent the forming paper sheet from being damaged.
(2) Fracture length
The breaking length indicates the magnitude of tensile strength that paper can withstand. It is calculated based on the assumption that one end of a paper or cardboard of a certain width is suspended, and the maximum length that breaks due to its own weight is expressed in kilometers. There are many factors that affect the breaking length of paper, mainly the binding force of fibers and the average length of fibers. At the same time, it is related to the interweaving arrangement of fibers and the strength of the fibers themselves. At the initial stage of pulping, the fracture length increases rapidly, then gradually slows down, and after reaching a certain value, there is a phenomenon of turning and decreasing. This is because in the early stage of pulping, the rapid swelling and fine fiber formation of fibers increase the binding force of the fibers, and the breaking length also rises accordingly. At this stage, the main factor affecting the breaking length is the binding force of the fibers. When the degree of pulping of wood pulp is around 70°SR and that of straw pulp is around 50°SR, the breaking length reaches its maximum value. Continuing the pulping process, although the fiber bonding force continues to increase, as the average length of the fibers decreases, the breaking length has begun to decline. The main factor influencing the breaking length in the latter section is the average length of the fibers. The timing of the turning point phenomenon is related to the pulping method. If heavy knives are used for pulping, the fiber length decreases rapidly and the fracture length turns earlier. Conversely, when using a light knife for pulping, less fiber is cut, which is conducive to increasing the breaking length and also results in a later turning point. The variation law of the breaking length also provides a reference for choosing the appropriate Polyester Forming Screen Forming Fabric model to better match the paper sheet forming with different strength requirements.
