Core-spun yarn series products have always been an important branch of the textile market. This series of products has a wide variety and variety, which can highlight the wearing personality of clothing, and is quite popular in the domestic and foreign textile and clothing markets. Domestic core-spun yarn production technology and quality are still stuck in low-end technological transformation, and core-spun yarn products are restricted. Core-spun yarn is generally made of synthetic fiber filament with good strength and elasticity as the core yarn, and the outer short fibers such as cotton, wool, viscose fiber and other short fibers are twisted and spun together. It has both filament core yarn and outer short fiber. Excellent performance. The more common core-spun yarn is polyester-cotton core-spun yarn, which uses polyester filament as the core yarn and is wrapped with cotton fiber. There is also spandex core-spun yarn, which uses spandex filament as the core yarn and is wrapped with other fibers. However, due to the outer covering of inelastic short fibers, the core filaments are generally exposed when stretched. It causes the fabric surface to appear white, affecting the appearance of the fabric and the overall value of the product.
The new pure cotton sheath-core structure core-spun yarn overcomes the shortcomings of the traditional core-spun yarn. The outer fiber is made of pure cotton fiber, and the core yarn is made of pure cotton spun yarn. The inner and outer fiber properties are consistent. The color is applied evenly during the dyeing process. Since the yarn is spun with a lower twist, the yarn feels fluffy and soft. The knitted fabrics or denim fabrics woven with it have clear and smooth textures, can stretch freely when worn, are comfortable and fit, are strong and wear-resistant, and can be used to make various high-end denim clothing, sportswear, etc.
Characteristics and production difficulties of a new pure cotton sheath-core structure core-spun yarn
1. New pure cotton sheath-core structure Characteristics of yarn
This kind of yarn can meet the weaving requirements of the subsequent processes (except for air-jet looms) by choosing a lower twist. The yarn has less hairiness and the knitted fabric has less skew.
It feels soft, has good water absorption and even dryness.
Compared with the traditional cotton-wrapped filament core-spun yarn process, a better coating effect can be achieved when the twist is not high.
Since the outer fiber and core yarn are made of the same material, the dyeing uniformity is good, which can improve the overall quality of the product.
Since a single yarn is used as the core yarn, the yarn twist is not required to be high. The yarn is uniform and soft, has high strength, can meet the requirements of high-speed weaving, and is widely used.
If colored cotton is used as the outer fiber and pure cotton natural color single yarn is used as the core yarn, a unique exposed white effect can be obtained. As a yarn for imitating denim, it has a unique style.
2. Analysis of difficulties in the production technology of new pure cotton sheath-core structure core-spun yarn
Production on existing equipment, space and core yarn The feeding method is limited, so some improvements need to be made to the spinning equipment. The space above the roving spindle frame (roof) of the spinning machine is rationally used to install the core wrapping device. An aluminum tube is used as the core yarn channel, which can effectively reduce dust. , the adsorption effect of hairiness. Reasonably configure the ratio of core yarn and outer fiber to optimize the spinning tension and ensure uniform coverage. High-pressure gas is used to bring the core yarn from the inlet above the aluminum tube to the outlet below the aluminum tube to facilitate workers’ operation. In the production process, it is necessary to optimize the core yarn count through experiments and select a reasonable core yarn package form.
Design of the second process route
FA006 automatic cotton picking machine → FA224 carding machine → RSB-401C Rieter draw frame Machine → EJK211 roving frame → FA506 spinning frame (renovation) → Savio automatic winding machine.
Selection of process parameters in three productions
1. Selection of core yarn count
Products It requires low twist and soft hand feel, but the strength should not affect the weaving efficiency. If traditional spinning technology is used, low twist cannot guarantee strength and the spinning efficiency is also very low. Therefore, we use various experimental plans to determine the ratio of core yarn to outer fiber.
A large number of experimental results show that core-spun yarn can be produced with a core yarn ratio of 10-40%, but only by selecting an appropriate core yarn and outer fiber ratio can the yarn strength index be guaranteed. When the core yarn ratio is 25-30%, the yarn strength index is better. If it is lower than this ratio, the strength of the core-spun yarn will be significantly lower; if it is higher than this ratio, the outer cotton fibers will be entangled weakly, making it difficult to form a yarn. There are many broken heads, and the strength cannot be guaranteed. In the end, we chose C58.3 package with 14.6tex (the finished yarn is 58.3tex, the core yarn 14.6tex is ordinary ring-spun spun yarn, the twist coefficient is 420, and the breaking strength is 15N/tex). The core yarn accounts for about 25%. At this time, the spinnability Best, the product quality can meet the weaving requirements.
2. Selection of core yarn package form
At present, textile mills generally use two core yarn package forms, tube yarn package and tube package. Yarn package. The core yarn is usually a parallel package package, or a traditional tapered package can be used, using axial unwinding. Through comparative experiments, we chose to use the flat yarn package with the best spinnability. During the unwinding process, appropriate unwinding tension must be maintained to ensure that the core yarn does not relax. There is no need for a spandex yarn pre-drafting device used to produce traditional spandex core-spun yarn. The winding length of the package yarn is long, and there are fewer yarn changes at joints, which effectively ensures the quality of the yarn and reduces the labor intensity of workers. The self-developed device is used to solve technical problems such as package yarn unwinding and core yarn transportation.
3. Selection of twist
In order to achieve a certain yarn strength, generally the twist coefficient of elastic yarn or filament core-spun yarn will be Control it at around 400. The new pure cotton sheath-core structure core-spun yarn uses a single yarn as the core yarn, so the twist requirements are not high. In order to achieve the characteristics of the product that is both soft and comfortable, high-strength and suitable for weaving, we choose the core-spun yarn with a core yarn of 14.6tex. A twist optimization experiment was conducted (see Table 1)
It can be seen from the above experimental data Experiment No. 1 uses a twist coefficient of 280, and the yarn strength is 698.4cN, which can fully guarantee the normal weaving requirements of the yarn, and all indicators are superior. Therefore, higher twist coefficient production is no longer used.
4. Selection of cotton blending
Based on long-term production practice and comprehensive consideration of efficiency and yarn strength, we choose C58.3T cotton blending as the package. For the covering yarn and cotton, choose C18.2A cotton as the core yarn and cotton. The specific indicators are shown in Table 3.
All the tested indicators of this product are higher than the national cotton natural yarn standard GB/T 398-93. The quality is stable and the production is smooth. Customers have reported after using it to produce high-end fabrics that the fabrics woven have unique styles and excellent performance.
Four Conclusion
Traditional cotton-spandex core-spun yarn is not allowed to show white since the core yarn is spandex yarn. However, some manufacturers have improper production management during the production process, often causing “missing wire” defects. The new type of pure cotton sheath-core structure core-spun yarn has a unique approach. According to the needs of the fabric style, colored cotton is used as the outer fiber, and the natural color cotton yarn is used as the core yarn. This deliberately produces a whitening phenomenon, so that the white pure cotton core yarn is exposed, showing a white appearance on the fabric. The unique style can be used to imitate denim fabrics. Due to the low twist of the yarn, the fabric feels soft and is suitable for yarn-dyed clothing such as towels and denim. The yarn can be used for both knitting and weaving. The fullness, bulkiness, softness and other wearing properties of the fabric are greatly improved. The product is favored by many customers and is in line with market trends. </p
