Disposable diapers are easy to carry without cleaning and easy to replace. They have been welcomed by consumers in recent years. Core is the core technology of products. With the development of technology and materials, the development of core layer is narrower, thinner and lighter. Ultra thin products first appeared in Western Europe and North America. At present, the ratio of polymer water absorbent resin / fluff pulp in this region is 60 / 40, that in the Middle East is 50 / 50, and that in China is also 50 / 50. The general trend in the future is to gradually increase the content of sap and super absorbent resin.

Core structure of traditional disposable diaper

The traditional disposable diaper core is usually composed of upper and lower toilet paper and / or absorbent materials smelled in the non-woven package. Water absorbent material is usually a mixture of sap and fluff pulp in a certain proportion. SAP plays the role of absorbing and locking water. Fluff pulp can improve the diffusion and absorption speed of core liquid, with complementary functions and good dryness. SAP / fluff slurry mixture shall try to maintain the flatness and softness of the product and prevent the polymer from slipping into a pile. Of course, this can only delay and weaken the mass, which can not be completely avoided. When the user walks around for many times, it is easy to accumulate fluid, especially when the user absorbs water together.

Core structure of composite disposable diaper

The composite disposable diaper core is usually a multi-layer structure formed by dust-free paper wrapped with non-woven fabric and fluffy non-woven fabric. Sap is added between layers and bonded by hot sol. Without adding fluff slurry, sap in the core completely absorbs and locks water, making the core lighter. Each layer of material is bonded with hot-melt adhesive. After absorbing water, it expands as a whole, is flat and free of lumps, and can maintain its original shape after absorption. However, SAP swelled into rigid hydrogel, which reduced the overall permeability and made the baby feel uncomfortable after wetting. In addition, this type of process is complex, the production speed of equipment is low, relatively traditional and the cost is high.

Core structure of 3D disposable diaper

3D composite disposable diaper core is usually upper and lower non-woven fabric, with 3D printing saf between layers. Three dimensional printing realizes the selective distribution of SAF in the core, with more middle distribution and less distribution on both sides. The thickness of the core absorption layer of 3D composite disposable diaper is reduced to 0.4 ~ 1.2mm, which is a real ultra-thin product. After liquid absorption, it forms a special shape to improve the dry touch of the product. In addition, SAF can absorb water and expand into soft fiber hydrogel. The fiber has a certain gap and good permeability, and the comfort of baby will be improved after wetting.

3D printing brings unlimited possibilities for further upgrading of disposable diaper composite core. The composite core absorbent layer using 3D printing technology is no longer granular sap or fluff pulp, but super absorbent fiber. With its ultra-thin and high quality, it has become a trend of the future development of the core. In this experiment, the structure of 3D composite core is analyzed and its related properties are studied, which provides a reference for the sustainable development of composite core in China.