Printing and dyeing tips │ Deliberate white core yarn [Yarn Technology]

The traditional cotton spandex core-spun yarn does not allow whitening because the core yarn is spandex. However, some manufacturers have improper production and management in the production process, and often produce "leakage" defects. The new pure cotton core structure core-spun yarn is unique. According to the needs of the fabric style, color cotton is used as the outer core fiber. The natural cotton yarn is used as the core yarn. The whitening yarn is exposed deliberately and the white cotton core yarn is exposed and displayed on the fabric. The unique style can be used to imitate denim fabrics. Due to the low yarn twist, the fabrics are soft to the touch and are suitable for dyed garments such as towels and denim. The knitting and weaving of the yarn can be used. The fullness, fluffiness, and softness of the finished fabric are greatly improved. The products are favored by many customers and are in line with the market trend.

Core yarn products have always been an important branch of the textile market. This series of products has a wide range of products and a variety of different types. It can highlight the wearing personality of clothing and is popular in the domestic and international textile and clothing markets. The domestic core yarn production technology and its quality still remain at the low-end technological transformation, and the core yarn product is limited. The core yarn is generally made of synthetic fiber filaments with good strength and elasticity as core yarns. Outsourcing cotton, wool, viscose fibers, and other short fibers are twisted and spun together to produce both filament core yarns and outsourcing staple fibers. Excellent performance. The more common core yarns are polyester/cotton core yarns, polyester filaments as core yarns, and cotton fibers. Spandex core-spun yarns are also used, and spandex filaments are used as core yarns to cover the yarns made from other fibers. However, due to the outsourcing of non-elastic staple fibers, the core filaments are generally exposed when stretched. Causes the fabric surface to be white, affecting the appearance of the fabric and the overall value of the product.

The new type of pure cotton core structure core-spun yarn overcomes the disadvantages of the traditional core yarn. The outer fiber uses pure cotton fiber. The core yarn uses pure cotton spun yarn. The properties of the inner and outer fibers are the same, and they are evenly colored in the dyeing process. Due to the low twist spinning, the yarn feels fluffy and soft. The knitted fabric or denim fabric woven into it has the advantages of clear and smooth lines, flexibility when worn, comfortable fit, high strength and wear resistance, and can be used for various high-grade denim clothing, sportswear and the like.

1 The characteristics and production difficulties of new type pure cotton core structure core-spun yarn

1.1 The characteristics of the new pure cotton core structure yarn

This kind of yarn can meet the weaving requirements of the subsequent process (except for air jet looms) with a lower twist. The yarn has less hairiness and the knitted fabric is less skewed.

Feel soft, absorbent, and evenly dry.

Compared with the traditional cotton-wool filament core-spun yarn technology, a better coating effect can be obtained when the twist is not high.

Due to the consistency of the outer fiber and the core yarn, the dyeing uniformity is good and the overall quality of the product can be improved.

Because single yarn is used as the core yarn, the yarn does not require high twist, the yarn is uniform and soft, and the strength is high. The yarn can meet the high-speed weaving requirements and is widely used.

If the color cotton is used as the outer core fiber and the pure cotton single yarn is used as the core yarn, a unique dew-white effect can be obtained. As the artificial denim yarn, the style is unique.

1.2 Analysis of Difficulties in Production Technology of New Type Pure Cotton Core Structure Core-spun Yarn

In the existing equipment, the space and core yarn feeding methods are limited, so it is necessary to make some improvements to the spinning equipment and reasonably use the space above the roving frame (roof) of the spinning frame to install the core device. The aluminum tube is used as the core yarn channel, which can effectively reduce the adsorption of dust and hairiness. Reasonably arrange the proportion of core yarn and outsourcing fiber, optimize the tension of the spinning yarn, and ensure even coating. The high-pressure gas is used to bring the core yarn from the upper inlet of the aluminum tube to the lower outlet of the aluminum tube to facilitate worker operation. In the production process, the number of core yarns should be selected through testing, and a reasonable core yarn package type should be selected.

2 Design of the process route

FA006 automatic picking machine→FA224 carding machine→RSB-401C Rieter draw frame→EJK211 roving frame→FA506 spinning frame (retrofitting)→Savio automatic winder.

3 Selection of Process Parameters in Production

3.1 The choice of core yarn count

The product requires low twist and soft hand, but strong can not affect the weaving efficiency. If traditional spinning processes are used, low twist does not guarantee strength and spinning efficiency is very low, so we use a variety of test schemes (see Table 1) to determine the ratio of core yarns to outer fibers.

A large number of experimental results show that core yarn core yarns can be produced in 10-40% of the core yarns, but only by selecting the appropriate ratio of core yarns and outsourcing fibers can we ensure the yarn strength index. When the core yarn ratio is between 25-30%, the yarn strength index is better. Below this ratio, the core yarn strength will be significantly lower. Above this ratio, the outer layer of cotton fibers will be less entangled and will not be formed successfully. There are many more broken ends and strength cannot be guaranteed. In the end, we chose C58.3 package 14.6tex (58.3tex yarn, 14.6tex core yarn for regular ring spinning, twist factor 420, breaking strength 15N/tex), core yarn accounted for about 25%, spinnability at this time Preferably, the product quality meets the weaving requirements.

3.2 The choice of core yarn package

At present, textile mills generally use two types of core yarn packages, bobbin packages and bobbin packages. The core yarn is generally a package of parallel packages, but it is also possible to use a conventional conical package and an axial unwinding method. Through comparative tests, we chose to use the best bobbin package with the best spinnability. During the unwinding process, proper unwinding tension should be maintained to ensure that the core yarn does not loosen, and the spandex pre-drafting device for producing the traditional spandex core-spun yarn is not needed. The winding length of the bobbin yarn is long and there is less yarn change in the joint, which effectively guarantees the yarn quality and reduces the labor intensity of the workers. The self-developed device solves the technical problems of unwinding and core yarn transportation.

3.3 The choice of mobility

In order to achieve a certain yarn strength, the twist coefficient of the core yarn of elastic yarn or filament core yarn is controlled at about 400. The new pure cotton core structure core-spun yarn uses single yarn as core yarn, so the requirement for twist is not high. In order to achieve the characteristics of softness, comfort, strength and suitability for weaving, we choose core yarn with core yarn of 14.6tex. A mobility optimization experiment was performed (see Table 2).

From the above experimental data, it can be seen that the No. 1 experiment adopts a twist factor of 280, and the yarn strength of 698.4 cN can fully guarantee the normal weaving requirements of the yarn, and all the indexes are superior. So no longer use the higher coefficient of production.

3.4 Selection of cotton

According to the long-term production practice, considering the benefits and yarn strength, we chose C58.3T cotton as cover yarn and cotton, and C18.2A cotton as core yarn and cotton. The specific indicators are shown in Table 3.

Table 3 Comparison table with cotton

This product has been tested in various indicators are higher than the national cotton yarn color standard GB/T 398-93, stable quality and smooth production. After the customer uses the high-grade fabric to produce feedback, the woven fabric has a unique style and excellent performance.

4 Conclusion

The traditional cotton spandex core-spun yarn does not allow whitening because the core yarn is spandex. However, some manufacturers have improper production and management in the production process, and often produce "leakage" defects. The new pure cotton core structure core-spun yarn is unique. According to the needs of the fabric style, color cotton is used as the outer core fiber. The natural cotton yarn is used as the core yarn. The whitening yarn is exposed deliberately and the white cotton core yarn is exposed and displayed on the fabric. The unique style can be used to imitate denim fabrics. Due to the low yarn twist, the fabrics are soft to the touch and are suitable for dyed garments such as towels and denim. The knitting and weaving of the yarn can be used. The fullness, fluffiness, and softness of the finished fabric are greatly improved. The products are favored by many customers and are in line with the market trend.