Absorbent paper is a kind of special paper in household paper, which plays an irreplaceable role in disposable sanitary products. At present, it is mainly used for wrapping paper of composite cores such as sanitary napkins and diapers, which has the effect of accelerating the absorption and diffusion of liquid. As the coating paper for the core, its air permeability directly affects the air permeability of the core after absorbing water. At the same time, the higher the permeability, the faster the absorption rate and the better the diffusion performance. Therefore, the research on the permeability of down tissue has practical guiding significance.

1.Effect of the ratio of needle wood pulp and broadleaf wood pulp on absorbent paper permeability

The papermaking of absorbent paper is mainly bleached kraft softwood pulp, and a certain proportion of hardwood pulp is added. Because coniferous wood pulp has long fibers and good fiber interweaving ability, it can still maintain a large tensile resistance under high wrinkling rate and elongation. Due to the low beating degree, the fiber combination is not tight, the fiber gap is large, and the air permeability between fibers is good. Broad leaved wood pulp has short fiber and contains more hemicellulose, which enhances the adhesion between fibers. Although the short fiber can improve the uniformity and softness of the paper, the air permeability is poor. Through experiments, it can be concluded that when the ratio of coniferous wood pulp reaches 70, the physical indexes can meet the requirements, and the air permeability of the paper is relatively good.

2.Effect of needle wood pulp beating on absorbent paper permeability

Reasonable beating process is the key to ensure various physical indexes of paper. Absorbent paper usually uses long and short fibers for beating separately. Coniferous wood pulp needs to be cut and brushed to some extent, because its single fiber is long. Because the fiber of hardwood pulp is short, it can only be dredged. Try to disperse the fiber without cutting it off. Therefore, the beating effect of softwood pulp directly affects its air permeability. Through experiments, we can draw a conclusion that when the beating degree is 25~27 ° Sr, the paper has the best air permeability and saves power consumption.

3.Effects of softwood pulp types on absorbent paper permeability

The selection of raw materials plays an important role in the performance of paper, and the physical indexes of paper depend on the fiber morphology. For example, cell wall thickness, cell cavity diameter, content of miscellaneous fibers, microstructure of fiber wall, etc. Therefore, the tensile force and air permeability should be considered at the same time, and appropriate raw materials should be selected to improve the air permeability of absorbent paper.

4.Effect of elongation on permeability of absorbent paper

In view of the unique wrinkling and elongation of household paper, the fluffy degree of the paper is increased, the tightness and stiffness are reduced, and the fiber interweaving is damaged. Due to the increase of capillary in the paper, it is not only conducive to the penetration of solution in the paper, but also increases the number and size of pores and improves the air permeability. Therefore, when the wrinkling rate and elongation are high, higher air permeability can be obtained, but at the same time, the production efficiency is reduced. Considering the thickness, on the premise of satisfying a certain thickness, increasing the wrinkling rate and elongation can improve the air permeability of the paper. Therefore, properly increasing the elongation can improve the permeability of absorbent paper.

With the help of production practice, by discussing the factors affecting the permeability of absorbent paper, the following conclusions are obtained: (1) the main factors affecting the permeability are not only related to the types of fiber raw materials coniferous wood pulp, but also related to the technological parameters such as the ratio of coniferous wood pulp, beating degree and elongation of paper in the process of papermaking. (2) The permeability of the paper can be improved by selecting the softwood pulp with large fiber coarseness, lower beating degree, higher ratio of softwood pulp and larger elongation. However, down tissue, as the paper covering the core body of diapers, in addition to physical indicators such as air permeability and strength performance, other aspects such as appearance and feel also need to meet the requirements of post-processing, which should be considered comprehensively in the production process.