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Hot air penetration bonding reinforcement principle of diapers

# Diapers

There are many kinds of diaper related processes, and even the production processes of different manufacturers will be different. For the hot air penetration bonding composite guide layer material, there are many steps in the processing process, and the hot air penetration bonding reinforcement is a part of it. Therefore, before understanding the whole processing principle, we must understand the reinforcement principle in advance.

Introduction to synthetic fiber of diapers

The synthetic fiber of diaper is usually a mixture of amorphous region and crystalline region. The existence of crystallization zone makes the fiber have certain strength and modulus; The existence of amorphous region can make the macromolecular chain of fiber move freely, and make the properties of fiber close to amorphous polymer. It has the unique mechanical properties of amorphous polymer such as glass, high elasticity and viscous flow.

The volume of liquid and solid matter consists of two parts. One part is the volume occupied by molecules, which is called occupied volume; The other part is the volume not occupied by molecules, which is called free volume. The latter is dispersed in the whole material in the form of "holes". Due to the existence of free volume, the conformation of molecular chain can be adjusted by rotation and displacement. When the polymer cools and begins to enter the glassy state, the free volume decreases gradually. When it reaches a certain temperature, the free volume will reach the lowest value. In the glass state, because the motion of the chain segment is frozen, the free volume is also frozen, so the constant value will remain unchanged, and the size and distribution of the free volume are basically fixed. Therefore, the glass temperature is the temperature at which the free volume reaches a certain critical value. Below this critical value, there is not enough space to adjust the molecular chain image, so the glass state of the polymer is regarded as an equal free volume state.


Hot air penetration bonding mechanism of diapers

This mechanism is the use of hot air to penetrate the diaper fibers. When the fiber web horizontally passes through the hot air drying oven, it absorbs heat through heating to reach a certain temperature. Due to the low melting point, the bonded fiber begins to soften and melt. The conformation of fiber macromolecular chain in non product area changes microscopically, and the whole macromolecular chain slides through the mutual migration of chain segments. The macroscopic performance is the viscous flow of fibers under the action of external force. At the same time, due to capillary penetration and molten fluid diffusion, it is better to bond with the main fiber. Because the bonded fiber has product area and amorphous area, complete melting takes a certain time, and the size of the bonding point between the bonded fiber and the main fiber will also be affected by factors such as complete melting, flow and diffusion, all of which will affect the properties of hot-air nonwovens.


After understanding the principle, it is helpful to analyze the process and improve the equipment. Mastering the whole process in advance can not only greatly improve the production efficiency. Similarly, it will also reduce unnecessary losses caused by a large number of operational errors. Further, it also plays a certain role in ensuring the quality of diaper products.


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