How to choose raw cotton
Raw cotton should be selected according to the linear density of the spinning yarn, the purpose of the yarn and the finishing characteristics. 1. Select raw cotton according to the yarn use and finishing characteristics (1) Combed yarn and carded yarn: Combed yarn is generally a high-end product that requires good appearance quality, uniform evenness, and few neps and impurities. Therefore, it is appropriate to choose raw cotton with long fiber length, good grade, moderate maturity, high strength, fineness, and fewer neps and impurities. Because combed yarn can release more lint during the finishing process, the raw cotton contains slightly more lint, which has no significant impact on the quality of the yarn. Carded yarn is mostly used in mid-range products, and the quality requirements for spinning yarn are not as high as combed yarn. Therefore, all cotton distribution indicators can be appropriately lower than combed yarn. Choosing raw cotton with less short lint will help improve the yarn strength of carded yarn, especially when spinning fine special yarns. (2) Warp yarns and weft yarns: Warp yarns have more chances to withstand tension and friction during the production process, so the warp yarns require higher strength. When blending cotton, raw cotton with slender fibers, higher strength, moderate maturity, and better uniformity should be used. Since there are more opportunities to remove neps and impurities on the spinning yarn during the planning and weaving processes and the warp yarns need to be sized, the requirements for the color and impurity content of the raw cotton for the warp yarns can be slightly lower. The weft yarn is not sizing, the planning process is simple, there are few opportunities to remove impurities, and the tension during weaving is small. Therefore, the weft yarn should be made of raw cotton with good color, less impurities, thicker and shorter, and slightly weaker strength. (3) Single yarn and ply yarn: The requirements for the strength and appearance defects of general single yarns are higher than those of single yarns used for plied yarns. The reason is that after single yarns are combined into plied yarns, the utilization rate of fiber strength can be improved and the appearance can be improved. Defects will be partially covered during merging, and evenness can also be improved by merging single yarns. Therefore, the single yarn used for strands has lower requirements for raw cotton than ordinary single yarns. (4) Yarn for knitted fabrics: Yarn for knitted fabrics requires high yarn strength, few defects, soft hand feel, even dryness and good color. Therefore, raw cotton with slender fibers, good uniformity, normal maturity, low lint strings and few defects should be selected. The yarn used for knitted fleece fabrics should be raw cotton with good maturity, good elasticity and short length. (5) Yarn for coloring: Cotton generally needs to be dyed and finished. The color absorption ability of fabrics has a lot to do with the properties of the fibers. Different shades of coloring have different requirements for raw cotton. Light-colored fabrics have high requirements for raw cotton, and raw cotton with low maturity and large differences cannot be mixed. Otherwise, if the mixture is uneven, stripes or spots will appear after coloring. Bleached fabrics and dark-colored fabrics may have lower requirements for raw cotton. For example, some yellow and white stripes on natural cotton fabrics can generally be removed after coloring or bleaching. (6) Yarn for seed holding: Special yarn should be selected from raw cotton according to different uses and characteristics. For example, the yarn used for tire cord fabric requires high strength, small elongation, and low requirements for color and appearance defects. When blending cotton, raw cotton with slender fibers and high strength should be selected, and the color and impurity content of the raw cotton are not required. Others such as embroidery yarn, sewing thread, handkerchief thread, etc. require the use of raw cotton with higher strength, good color and less neps and impurities. (7) Yarn for blended chemical fiber fabrics: The length of the cotton fiber in the blended chemical fiber fabric yarn should be completely close to the length of the chemical fiber. High-end fabrics of chemical fiber and cotton blended chemical fiber fabrics often use long-staple cotton or fine-staple cotton: mid-range fabrics Mainly mixed with fine velvet cotton. 2. Select the original forest according to the density of the spun yarn (1) Fine yarn: generally used for very high-end fine products, the yarn quality requirements are very high, the number of fibers in the cross section of the spun yarn is very small, and the difference in fiber number is important The strength and evenness of the spinning yarn have a significant impact. Small knots and defects are easily exposed on the surface of the spinning yarn, affecting breakage and evenness. Therefore, long-staple cotton or grade 1.2~1.8 and length 31.0 should be selected. —33.0mm velvet cotton. (2) Fine yarn: Fine yarn is mostly used in high-end fabrics or strands, and the yarn quality requirements are higher. Therefore, you should choose snow-white color, higher grade (1.5-2.8 grade), moderate maturity, higher fiber strength, smaller linear density, longer length (28-31mm), better uniformity and free from impurities and defects. Less raw cotton. (3) Medium special yarn: The quality of medium special yarn is generally lower than that of fine yarn. Therefore, you should choose raw cotton with slightly inferior color, slightly lower grade (2.3~3.5), average maturity and fiber linear density, shorter length (26.5~29.5mm), and fewer impurities and defects. (4) Coarse special yarn: The quality requirements of coarse special yarn are generally lower. The number of fibers in the cross section of the yarn is larger, which makes it easier to meet the strength requirements of the yarn. Therefore, you can choose raw cotton of lower quality or appropriately match some low-grade cotton and reused cotton. The general grade is 2.6-4.8, and the length is 25.5-27.5mm. See Table 3-1 for reference plans for cotton distribution of some conventional products.
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