Abnormal fiber types in polyester cotton
During the production of polyester cotton, some abnormal fibers may occur due to the condition of the front or back spinning, especially when using recycled cotton slices for production, which is more prone to producing abnormal fibers; Abnormal fiber outsole can be divided into the following types:
（1） Single coarse fiber: a fiber with incomplete extension, which is prone to dyeing abnormalities and has less impact on non-woven fabrics that do not require dyeing. However, it has a serious impact on water needle or needle punched fabrics used for artificial leather base fabrics.
（2） Filament: Two or more fibers stick together after extension, which can easily cause abnormal dyeing and have less impact on non-woven fabrics that do not require dyeing. However, it has a serious impact on water needle or needle punched fabrics used for artificial leather base fabrics.
（3） Gel like: During the extension period, broken or tangled fibers are produced, causing the fibers to not extend and form hard cotton. This product can be divided into primary gel like, secondary gel like, tertiary gel like, etc. After the carding process, this type of abnormal fiber often deposits on the needle cloth, causing poor formation or breakage of the cotton net. This raw material can cause serious quality defects in most non-woven fabric products.
（4） Oil free cotton: During the extension period, due to poor driving conditions, there is no oil on the fibers. This type of fiber usually has a dry feel, which not only causes static electricity in the non-woven fabric production process, but also leads to problems in the post-processing of semi-finished products.
（5） The above four types of abnormal fibers are difficult to remove during the production of non-woven fabrics, including single thick fibers and tangled fibers. However, adhesive and oil-free cotton can be removed with a little attention from production personnel to reduce product quality defects.
Reasons affecting the flame retardancy of non-woven fabrics
The reasons why polyester cotton has a flame retardant effect are as follows:
（1） The oxygen limiting index of conventional polyester cotton is 20-22 (with an oxygen concentration of 21% in the air), which is a type of combustible fiber that is easy to ignite but has a slower combustion rate.
（2） If the polyester slices are modified and denatured to have a flame retardant effect. Most of the long-lasting flame-retardant fibers are produced using modified polyester chips to produce flame-retardant polyester cotton. The main modifier is a phosphorus series compound, which combines with oxygen in the air at high temperatures to reduce oxygen content and achieve good flame-retardant effects.
（3） Another method to make polyester cotton flame retardant is surface treatment, which is believed to reduce the flame retardant effect of the treatment agent after multiple processing.
（4） Polyester cotton has the characteristic of shrinking when exposed to high heat. When the fiber encounters a flame, it will shrink and detach from the flame, making it difficult to ignite and producing an appropriate flame retardant effect.
（5） Polyester cotton may melt and drip when exposed to high heat, and the phenomenon of melting and dripping produced by igniting the polyester cotton can also take away some of the heat and flame, producing an appropriate flame retardant effect.
（6） But if the fibers are coated with easily combustible oils or silicone oil that can shape the polyester cotton, the flame retardant effect of the polyester cotton will be reduced. Especially when polyester cotton containing SILICONE oil agent encounters flames, the fibers cannot shrink and burn.
（7） The method of increasing the flame retardancy of polyester cotton is not only to use flame-retardant modified polyester slices to produce polyester cotton, but also to use oil agents with high phosphate content on the fiber surface for post-treatment to increase the flame retardancy of the fiber. Because phosphates, when exposed to high heat, release phosphorus molecules that combine with oxygen molecules in the air, reducing the oxygen content and increasing flame retardancy.
Reasons for static electricity generated during non-woven fabric production
The problem of static electricity generated during non-woven fabric production is mainly caused by the low moisture content in the air when the fibers and needle cloth come into contact. It can be divided into the following points:
（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） Low fiber oil content and relatively low electrostatic agent content can also generate static electricity.
（4） Due to the special molecular structure of the oil agent, SILICONE polyester cotton contains almost no moisture on the oil agent, making it relatively more susceptible to static electricity during production. The smoothness of the hand feel is usually proportional to the static electricity, and the smoother the SILICONE cotton, the greater the static electricity.
（5） The method of preventing static electricity is not only to increase humidity in the production workshop, but also to effectively eliminate oil-free cotton during the feeding stage.
Why do non-woven fabrics produced under the same processing conditions have uneven thickness
The reasons for uneven thickness of non-woven fabrics under the same processing conditions may include the following points:
（1） 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. For example, Japan’s 4080, South Korea’s 4080, South Asia’s 4080, or Far East’s 4080 all have different holding forces. If low melting point fibers are unevenly dispersed, the parts with less low melting point fiber content cannot form a sufficient mesh structure, and non-woven fabrics are thinner, resulting in thicker layers in areas with more low melting point fiber content.
（2） Incomplete melting of low melting point fibers: The main reason for incomplete melting of low melting point fibers is 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.
（3） High shrinkage rate of fibers: Whether it is conventional fibers or low melting point fibers, if the hot air shrinkage rate of fibers is high, it is also easy to cause uneven thickness during the production of non-woven fabrics due to shrinkage problems.
Why do non-woven fabrics produced under the same processing conditions 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. 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.
Thinner non-woven fabrics are more prone to short sizes
When winding non-woven fabric, the finished product becomes larger as it is rolled. 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.
Reasons for the formation of hard cotton after wrapping the eight work rolls with cotton
Answer: During production, the main reason for cotton wrapping on the work roll is due to low oil content on the fibers, which causes abnormal friction coefficient between the fibers and the needle cloth. The fibers sink below the needle cloth, resulting in cotton wrapping on the work roll. The fibers wrapped 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. In addition, encountering a long sleep can also easily lead to the problem of lingering work rolls.
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Post time: Aug-14-2024