The diversion Layer is a special nonwoven material placed between the topsheet and the absorbent core. It can effectively help the rapid transfer of liquid from the surface coating material and distribute the liquid to the longitudinal direction, so that the liquid quickly leaves the user's skin and enters the SAP absorbent core. When the baby excretes urine, it is first received and penetrated into the urine by the pull-ups surface layer, and then the urine is received through the diversion layer. Part of the urine is directly absorbed by the SAP absorbent core, and the rest of the liquid is conducted and diffused in the longitudinal direction, and finally the urine is diffused and penetrated in the longitudinal direction. It is evenly absorbed by the SAP absorbent core and expands the absorption area of the SAP absorbent core.
According to chemical composition and molecular structure analysis, SAP is a cross-linked polymer electrolyte, and its molecule contains both hydrophilic groups and hydrophobic groups. When the hydrophilic group is in contact with water molecules, it will interact to form various hydration states; due to the hydrophobic effect, the hydrophobic base is easily folded to the inside, forming a local insoluble granular structure. The product mainly relies on SAP and wood pulp to absorb and lock the liquid, But the swollen portion of the SAP restricts subsequent fluid entry, greatly reducing the overall effective absorbent capacity of the entire diaper and increasing the likelihood of leakage. Therefore, if the expansion rate of the SAP in the absorbent core is slowed or retarded, the overall wicking performance can be improved. Adding a conducting layer to the product can effectively diffuse and distribute the liquid in the conducting layer, and at the same time be absorbed by SAP slowly and evenly, which greatly improves the performance of liquid absorption.
According to the research, the application of the diversion layer has the following characteristics: firstly, it accelerates the longitudinal absorption of liquid and effectively prevents side leakage; The local absorption is saturated, the re-infiltration is reduced, and the skin is kept dry; the product is thinner, and even if the SAP content is reduced, the same dryness as the non-conductive layer pull-ups can be obtained.
Compared with the urine diffusion without the use of the diversion layer, the liquid absorption part of the SAP absorbent core is mainly concentrated in the oval part, and the liquid absorption area A2 of pull-ups is much larger than the unused liquid absorption area A1, of which the liquid absorption area A can be used. The formula is approximated. It is believed that the actual suction area of the planar diversion can approximately replace the ellipse area, dm is the longitudinal diffusion length of urine, recorded as the diameter of the long axis of the ellipse, and dc is the lateral diffusion length of the urine, recorded as the diameter of the short axis of the ellipse. Therefore, the actual suction area of the plane can be approximated by A=π/4dm*dc.
To sum up, the main function of the diversion layer is to guide the urine permeating from the surface to conduct and diffuse longitudinally along the pull-ups, so that the urine is evenly absorbed by the absorbent core, preventing the pull-ups from locally thickening, and preventing subsequent urine from being absorbed by the absorbent core.