Requirements And Standards For Cotton Yarn For Knitted Fabrics

Requirements and standards for cotton yarn for knitted fabrics

In the past two decades, the cotton spinning industry has undergone great changes. In terms of yarn quality characteristics, through continuous improvement and experience accumulation, a series of quality data and suitable parameters represented by these data have been determined to achieve yarn production and yarn weaving. The consensus of cloth processing has gained international recognition.

The weaving mill evaluates the quality of the yarn according to the processing capability and the appearance of the finished product, and establishes an acceptable quality standard. The yarn mill and weaving factory can produce and adopt according to this standard; use advanced testing instruments and constantly improve The standard of the cotton yarn to be produced by the spinning mill, according to the existing standard data to set its requirements for cotton, such as cotton fineness, maturity, sugar, impurities, strength, neps, etc., have a comprehensive range of Instrument testing, and then according to the data standard to set which count of the number of products; yarn quality, there are also a series of instrument testing and international and domestic standards for each project, such as strip uniformity, young, thick, Neps, hairiness, breaking strength, etc., all have standards, such as the USTER standard. There are different requirements for warp and weft yarns in the weaving process. For the warp yarns, the breakage rate, strength and hairiness are set to the standard, thereby improving the weaving speed and the woven fabric of the cotton yarn; if the yarn still remains, the yarn will be affected. The appearance, such as strips, coarse slub yarn, neps, etc., so these also have strict standards. Regardless of the method used and the acceptance criteria, the purpose and limitations of the control should be considered. With the fiber quality specification, there is a basic quality specification for yarn processing. With the yarn quality specification, there is a basic basis for weaving. Quality specifications. However, these standards are only used in woven fabrics and woven yarns. Although the production of knitted fabrics has grown continuously in the past ten years, especially in the circular knitting industry, the annual consumption of cotton yarn has been increasing. However, the requirements and standards for cotton yarn have not been developed simultaneously. So far, there has not been a comprehensive set of companies. Accepted quality standards. Here, I will make a simple analysis and introduction of the requirements and standards of cotton yarn for cotton yarn, for the reference in the industry.

(1) Actual count

The spinning mill sets the actual count, which is different in the production of knitted fabrics, which will affect the weight of the specifications. Because of the strong stretchability of the knitted fabric, the actual number of counts exceeds +/-5% after the experimental results. The standard specifications are adjusted. The adjustment range also needs to consider whether the standard yarn length of the fabric is within the acceptance range. The difference in color during dyeing has a great influence on the weight of the cloth. The weight loss rate of different dyes is also different, and the dye weight loss rate is tested (regardless of the weight loss of the finished product and the boiled cloth)

The above shows that the bleaching weight loss rate is more than 4%, and the dyed dark color is up to 1.78%. Therefore, the knitting yarn is used as the bleaching light color. The actual demand is too thick, so the standard should be +/-5% of my standard. +5/-0% range.

(2) Regain rate: It can be performed according to the standard public regain rate of 8.5%. GB4743.

(3) Temperature requirements:

Cylindrical knitted fabrics have a very close influence on the twist. Because the yarn mills generally produce Z-directions, during the spinning twisting process, the single yarns are twisted by external force, which causes the fibers to be deformed. The residual torque in the single yarn is The main factor that causes the coil to be skewed in the single-faced knitted fabric, thereby causing the fabric to be distorted, and it is also troublesome to eliminate. Therefore, the general knitting factory requires low requirements for cotton yarn. First, the spinning mill considers the relationship between twist and strength, and should choose the best twist to achieve the highest strength. Secondly, the twist is also limited by the length and fineness of cotton fiber. At present, the quality of cotton is generally declining, and the problem of short-fiber hairiness is serious. In order to reduce such problems, the spinning mill will also increase the temperature to improve the appearance of the fabric, so the basic standard requirements must be determined.

(4) Single yarn strength: Single yarn strength has a great influence on the woven fabric, especially the warp yarn must be strong, but the knitted fabric has high elongation, and the tension in the weaving process is lower than that of the weaving, so the single yarn The strong standard is used as a reference, and the test method can be implemented according to the national GB2543.

(5) Elongation: In the knitted fabric, the elongation can be used as a reference data, and the cotton yarn with a large difference in elongation may cause an abnormal appearance of the fabric when mixed and woven. Therefore, when testing single yarn strength, the standard value of elongation is -8% or more.

The above physical test items, the spinning mill data is very sufficient, and the weaving factory can also test it by simple instruments to evaluate whether the cotton yarn is suitable for its product application.

The early premise and the European test method are the appearance test of the finished fabric, and the final requirement of the weaving factory is determined on the appearance of the fabric, so the final weaving test needs to first test the cotton yarn. The yarn defect is most easily expressed on the single-yarn plain fabric, so the organization is arranged in the same shape of the same type of coil, so the test target is a single yarn plain weave, the weaving specification should be the standard specification, too much too dense and affect the yarn defect performance. The result is therefore:

The knitted fabric is divided into two sections, one for bleaching and one for dyeing (Sapphire and dark). The dyeing specifications can be determined according to the process standards of each dyeing factory, but the same conditions and methods are applied for each test. The items that have been tested are determined according to the appearance of the fabric and the requirements of the garment factory or ready-to-wear customer. The requirements of the customer are converted into the test items of the fabric, and the standard value and acceptance rate of the content are taken as the standard.