Author：Baby & Adult Diaper Materials FROM：Diaper Materials Manufacturer TIME：2023-03-07
During the processing of embossed hydraulic hot air non woven fabric,the hot air production process has a greater impact on product strength, that is, production speed (time), hot air temperature and air pressure. The balance between the three is the key to production.
The production speed of the hot air method is very high, which can reach 300m/min, and it is controlled below 100m/min in general production. If the production speed is too fast, that is, the heating time is too short, the fiber web cannot be heated evenly. The hot-melt fiber on the surface of the fiber web absorbs heat and melts, while the fiber in the inner layer does not absorb enough heat to fully melt. The bonding points between are reduced, the bonding force is deteriorated, the product strength is naturally reduced, and the product is prone to delamination; and the production speed is too slow, which will affect the output and increase the product cost.Book. Therefore, the control of production speed has become one of the most concerned issues of manufacturers. In this paper, the production speed is controlled at about 60m/min.
In the test, the temperature range of the hot air was selected between 138°C and 140°C. When the temperature is low, the melting area of PE is small, the melting is insufficient, the bonding effect is poor in the imperfect crystallization, and the product strength is low; if the temperature is too high, the crystal particle size will be large and brittle during the recrystallization process of the fiber, Stress concentration occurs at the fiber intersection point, which makes the fiber bonding force worse. In actual production, when the hot air temperature fluctuates by ±1°C, two embossed hydraulic hot air non woven fabrics with completely different properties can be produced. Therefore, when other process parameters remain unchanged, the product strength can be improved by appropriately increasing the temperature.
The hot air temperature should be 135°C higher than the melting temperature of PE. This is mainly because the hot air will lose part of the heat in the conveying pipeline. When the hot air reaches the surface of the fiber web to thermally bond it, the hot-melt fibers on the surface will absorb part of the heat. If the temperature of the hot air is too low, only the fibers on the surface of the fiber web can be completely melted, but the fibers on the inner layer of the fiber web are not fully melted, resulting in poor bonding effect of the fiber web, and delamination is very easy to occur under the action of external force.
The wind pressure in the hot air nonwoven process is similar to the roller pressure in the hot rolling nonwoven production, but the wind pressure is not the actual working pressure, because the fiber web is always in a free state during the processing. The hot air pressure does not change very much during the production process, but it still has a certain impact on the product strength: the frequency of the hot air blower increases, that is, the hot air pressure increases, and the product strength increases accordingly. This is because the hot air pressure is high, the hot air penetration is large, it is easy to heat the fiber web quickly and uniformly, the fiber hot-melt time is shortened, the PE in the cortex is fully softened and melted, the crystallization is perfect during cooling, and the bonding effect is enhanced. However, energy consumption needs to be considered in actual production. The increase of the hot air pressure can indeed increase the strength of the fiber web, but it is bound to increase the speed of the circulating fan, resulting in more hot air volume and increased energy consumption.
After years of production and development, embossed hydraulic hot air non woven fabric has been widely used in the whole hygiene industry. Its main downstream products include women's hygiene products, baby diapers, wet wipes, etc.
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