At present, the baby pants market is getting bigger and bigger. Many domestic brands are also developing gradually, but compared with foreign companies that started earlier, there is still much room for improvement in technology in this area. Especially in the diversion layer, there are few related studies. Therefore, this paper focuses on this layer, and briefly analyzes the structure of hot air penetration composite layer.

Fiber selectionof baby pants

At present, the diversion layer materials used in disposable sanitary products on the market are mainly polypropylene fibers and polyester fibers, which have a high melting point.

These fibers need to consume more energy during hot melt bonding, which will inevitably increase the cost of the product. Therefore, in order to reduce energy consumption and save costs, new fiber raw materials must be used to produce this material.

ES fiber is a kind of polyene strange fiber developed by Chisso Corporation of Japan. ES fiber has been highly evaluated in the world as a new type of thermal bonding composite fiber. ES fiber is a composite fiber with a skin-core structure with a melting point of 130°C and a core layer of polypropylene with a melting point of 165°C. In the production process of hot air penetration bonding, due to the low melting point of polyethylene as the skin layer component, the processing temperature is reduced, energy consumption is reduced, and costs are saved; ES fibers are well curled, and after hot air penetration bonding and reinforcement, the ES fibers melt at the point of interweaving, and the rest of the fibers remain intact, so there are pores between the fibers, resulting in a fluffy nonwoven fabric without binders.

In addition, ES fibers are generally not hygroscopic, and surfactants must be added to the surface of the fibers to reduce the contact angle of the fibers, thereby accelerating the absorption and diffusion of urine. Contact angle refers to the angle between the gas-liquid interface and the solid-liquid interface at the three-phase junction of gas, liquid and solid, and is a measure of wetting.

If the contact angle is less than 90°, the solid is lyophilic, that is, the liquid can wet the solid, and the smaller the angle, the better the wettability; if the angle is >90°, the solid is lyophobic, that is, the liquid wets the solid, The surface moves easily and does not enter pores. Therefore, the fibers used in the diversion layer material must be added with surfactants to make their contact angles less than 90°.

At the same time, this project also extensively investigated the research and development of materials at home and abroad. Through the DSC test of Kimberly Corporation of the United States, Mummy Baby of Unicharm Corporation of Japan and the popular baby pants diversion layer material in the Japanese market, it is found that the fiber has two obvious peaks between 130 ℃ and 165 ℃, so It can be deduced that the fibers used by Curiosity and Mommy Baby baby pants are ES fibers.

Structural design of composite diversion layerof baby pants

The liquid is diffused in the longitudinal direction of the guide layer material, which can expand the liquid absorption area of ​​the absorbent core. The liquid penetrates in the vertical direction, which can improve the vertical liquid absorption capacity of the absorbent core. Therefore, a good diversion layer material can only balance the vertical diffusion and vertical penetration of the liquid. Therefore, a new concept of composite material was designed, including the traditional diversion layer + damping layer. The fiber web adopts a fiber oriented arrangement structure, which can increase the diffusion of liquid in the fiber web; the random arrangement of the damping layer fiber web not only has a certain water permeability, but also prevents the liquid from permeating too fast and cannot diffuse in the diversion layer. This special structure maximizes the balance between the longitudinal diffusion and longitudinal penetration of the liquid in the material.

Don't look at the simple and thin baby pants small piece, but in the design process, not only pay attention to materials, but also conduct in-depth analysis of product structure. Only in this way can we find existing deficiencies and better improve our products.