Since the development of diapers, many properties have been optimized and the manufacturing process has been changed. At present, due to the common problems of diapers with pure core structure, the whole industry is forced to change the traditional structure and develop double core structure. However, double-layer applications still can not meet people's expectations. Because of this, people began to seek multi-layer design. Now, the fourth generation of multi-layer core has been born. Due to its optimization of previous generations, many peers began to look forward to better application of multilayer core in the market.

The double core is composed of core structure and wood pulp structure, which can effectively improve the water absorption speed of diapers and solve the problem of easy agglomeration and fracture of wood pulp structure. The double layer is characterized by abandoning the first and second generation production methods of one-time molding mainly by fluff pulp and polymer materials, and innovatively overlapping layers of nonwovens, dust-free paper and water absorbent polymers in the same proportion. The fourth generation is also called prefabricated core, because it is not once in the whole production process of diapers, but prefabricated.

Under the prefabrication technology, the fourth generation water absorbent polymer is evenly distributed, which makes the absorption and diffusion of urine faster and more uniform; The reasonable ratio of polymer to nonwovens makes it lighter and more breathable, breaking through the inevitable defects of the previous two generations, such as thickness, poor permeability, easy fracture, easy lump and so on. At the same time, it also improves the fatal defect of weak absorption performance in the third generation.

The fine layering technology of prefabricated multi-layer core can effectively improve its absorption capacity. Each layer of polymer has the functions of absorption, diversion speed, absorption speed, diffusion and water locking. It can be divided into 8 layers, of which 3 layers are evenly distributed and the content can reach more than 70%. After absorbing urine, the ultra-high content of water absorbent polymer can firmly lock the water, which is not easy to reverse osmosis and keep dry during the period. Although the number of precast core layers increases, it remains light, soft and breathable. The experimental data show that the reverse osmosis value of traditional wood pulp is generally more than 3G, while the fourth generation multi-layer reverse osmosis value is less than 1G. At the same time, due to the zoning technology, the surface layer adopts S-shaped ventilation groove, which reduces the contact between the skin and the diaper layer, leaving two ventilation channels, and further improves the permeability of the core on the basis of light weight.

It can be seen that the fourth generation multi-layer design is undoubtedly a leap forward in diaper innovation. Although it has not been widely used, with the continuous maturity of technology, I believe this technology will spread all over the global market and promote the fifth generation or even higher technology.