Many manufacturers produce non-woven fabrics that are always unqualified, sometimes with thin sides and thick middle, thin left side, or uneven softness and hardness. The main reason is that the following aspects are not done properly during the production process.
Why does non-woven fabric have uneven thickness under the same processing conditions?
Uneven mixing of low melting point fibers and conventional fibers
Different fibers have different holding forces. Generally speaking, low melting point fibers have greater holding forces than conventional fibers and are less prone to dispersion. If the low melting point fibers are unevenly dispersed, the parts with less low melting point fibers cannot form a sufficient mesh structure, resulting in thinner non-woven fabrics and thicker areas with higher low melting point fiber content.
Incomplete melting of low melting point fibers
The incomplete melting of low melting point fibers is mainly due to insufficient temperature. For non-woven fabrics with low basis weight, it is usually not easy to have insufficient temperature, but for products with high basis weight and high thickness, special attention should be paid to whether it is sufficient. The non-woven fabric located at the edge is usually thicker due to sufficient heat, while the non-woven fabric located in the middle is more likely to form a thinner non-woven fabric due to insufficient heat.
The shrinkage rate of fibers is relatively high
Whether it is conventional fibers or low melting point fibers, if the thermal shrinkage rate of the fibers is high, uneven thickness is also prone to occur during the production of non-woven fabrics due to shrinkage problems.
Why does non-woven fabric have uneven softness and hardness?
The reasons for uneven softness and hardness of non-woven fabrics under the same processing conditions are generally similar to the reasons for uneven thickness mentioned above, and the main reasons may include the following points:
1.Low melting point fibers and conventional fibers are mixed unevenly, with the parts with higher low melting point content being harder and the parts with lower content being softer.
2.Incomplete melting of low melting point fibers causes non-woven fabrics to be softer
3.The high shrinkage rate of fibers can also lead to uneven softness and hardness of non-woven fabrics.
Why is static electricity always generated during the production of non-woven fabrics?
1.The weather is too dry and the humidity is not enough.
2.When there is no oil on the fiber, there is no anti-static agent on the fiber. Due to the moisture regain of polyester cotton being 0.3%, the lack of anti-static agents results in the generation of static electricity during production.
3.Due to the special molecular structure of the oil agent, polyester cotton contains almost no water on the oil agent, making it relatively easy to generate static electricity during production. The smoothness of the hand feel is usually proportional to the static electricity, and the smoother the polyester cotton, the greater the static electricity.
4.In addition to humidifying the production workshop, it is also important to effectively eliminate oil-free cotton during the feeding stage to prevent static electricity.
Reasons for the production of hard cotton after the work roll is wrapped with cotton
During production, the entanglement of cotton on the work roll is mostly caused by low oil content on the fibers, resulting in abnormal friction coefficient between the fibers and the needle cloth. The fibers sink below the needle cloth, causing the work roll to become entangled with cotton. The fibers entangled on the work roll cannot be moved and gradually melt into hard cotton through continuous friction and compression between the needle cloth and the needle cloth.To eliminate tangled cotton, the method of lowering the work roll can be used to move and eliminate the tangled cotton on the roll.
The most appropriate processing qualitative temperature for low melting point fibers
The current melting point of low melting point fibers is advertised as 110 ℃, but this temperature is only the softening temperature of low melting point fibers. So the most appropriate processing and shaping temperature should be based on the minimum requirement of heating the non-woven fabric to a minimum temperature of 150 ℃ for 3 minutes.
Thinner non-woven fabrics are more prone to short sizes
When winding non-woven fabric, the finished product becomes larger as it is rolled, and at the same winding speed, the line speed will increase. Thinner non-woven fabric is prone to stretching due to lower tension, and short yards may occur after being rolled due to tension release. As for thicker and medium-sized products, they have higher tensile strength during production, resulting in less stretching and less likely to cause short code problems.
Dongguan Liansheng Non woven Technology Co., Ltd. was established in May 2020. It is a large-scale non-woven fabric production enterprise integrating research and development, production, and sales. It can produce various colors of PP spunbond non-woven fabrics with a width of less than 3.2 meters from 9 grams to 300 grams.
Post time: Dec-18-2024