Composite yarn—untwisted yarn composite fabric information

Composite yarn 1—untwisted yarn 1. Introduction As we all know, the pursuit of “softness” in products such as quilts and knitted underwear is always a major theme. In order to achieve “softness”, one of the requirements for yarns is to use as small a twist as possible. However, ordinary yarns have too small a twist. It will cause difficulties in spinning and increase the number of ends broken in weaving. Therefore, in the past, achieving “softness” could only be achieved by balancing spinning and weaving. Select a compromise value for the yarn twist requirements. The advent of untwisted yarn provides another brand-new solution to achieve “softness” for the quilt, knitting and other industries. The outstanding features of untwisted yarn products are super “softness” and water absorption. 1.1 Definition of untwisted yarn Yarn (twistless processing): A spinning method that uses an adhesive to bond the fibers in the fiber strips to each other into yarn. After the roving is drawn by the drafting device, the sliver is sent to the twisting drum, and the thin layer of adhesive from the tank on the return drum is contacted. The fiber sliver is transported forward together with the drum by several small rotating pressure rollers. , one of the small pressure rollers also makes axial reciprocating motion at the same time, rolling the fiber strips into a circular cross-section, so that each fiber can evenly contact the adhesive. The circular fiber strips are dried by the heater, and the fibers They stick to each other to form yarn. The spinning speed can be 2 to 4 times greater than the conventional spinning method, and the yarn produced can be used for weaving. An adhesive is used to bond the fibers in the yarn sliver to each other to form a yarn. There is no twist in the yarn sliver, and the strength is obtained by the mutual adhesion between the fibers. It is a new spinning method. 1.2 Development overview Untwisted yarn is a new type of yarn that appeared in the late 1970s. It is characterized by the fact that the fibers constituting the yarn are arranged in parallel and the cross-section of the yarn is in a ribbon shape. In the early 1980s, Texas Tech University Textile Rescarch Center (TRC) Lubbock, Tex introduced twistless yarn fabric to the market. Its fluffy, soft and soft luster effect was welcomed by the market. Untwisted yarn fabrics have formed a relatively rich range of knitted and woven products abroad. Domestic research on untwisted yarns started relatively late. It was not until the late 1990s that bonded untwisted yarns were introduced to the market and began to be used in knitted fabrics. , due to its excellent characteristics that are different from traditional yarns, it is receiving more and more attention. 1.3 Uses of untwisted yarn Home textile products (pajamas, bed blankets, quilts, towels, bath towels, shower caps, high-end uniforms, baby suits, pillowcases, etc.) are soft, bulky, sweat-absorbent, cotton, warm and light to wear , transparent and thin characteristics. 2. The yarn forming principle and method of untwisted yarn 2.1 The yarn forming principle consists of soluble PVA (polyvinyl alcohol) filament or mulberry silk wrapped on the surface of untwisted cotton bundles to form a wrapped yarn, which has better performance when weaving towels. Wear resistance and withstand a certain tension, and then dissolve PVA or mulberry silk in water after weaving into the finished product, so that the loops are in an untwisted and fluffy state in the fabric. 2.2 Yarn forming method 2.2.1 The bonding method uses bonding The mixture uses pseudo-viscosity to bind the fibers together tightly. The adhesion mixing of fibers can be done directly or during drawing. The yarn formed after the fibers are adhered and mixed on the draw frame can be directly supplied to the twistless worsted spinning machine after drying. It eliminates the four processes of traditional spinning process, namely two drawing processes, roving process and spinning process. This twistless yarn-forming method can increase yarn output 10 times compared to ring spinning. It overcomes the obstacles of high output in ring spinning and rotor spinning. Yarn can be spun directly from slivers, and some can even be spun directly from combs. The output of net-spun untwisted yarn is very large, which can reach 300~400 meters/minute. In addition, the distance between the drafting rollers can be adjusted to adapt to the spinning of fibers of different lengths, so as to realize the spinning of cotton yarn and yarn on the same machine. Wool yarn and other different types of yarn 2.2.2 Soft wrapping method This method uses parallel spinning method to spin the first yarn. The primary yarn is composed of soluble filament fibers and untwisted parallel short fibers. The soluble filament fibers are spirally wound around the untwisted parallel short fibers. The filaments are dissolved during the finishing process, leaving only the core without Twisted short yarn. In this process, the role of the filament is only to provide the tension required during the weaving process. 2.2.3 Reverse twist method raw materials: water-soluble vinylon thread + cotton yarn process: parallel thread → reverse twist. Process points: The reverse twisting process is the most critical process for processing untwisted yarn. The number of reverse twists of the ply yarn should be equal to the twist of the spun cotton spun yarn and PVA yarn. Use an appropriate small spindle speed and the height of the balloon should be appropriate. Increase the indoor humidity, increase the vinylon cohesion force, reduce the breakage, adjust the doubling tension and untwisting unwinding tension to solve the knotting phenomenon 3. Characteristics of untwisted yarn fabric 3.1 The main difference between untwisted yarn fabric and twisted yarn fabric 3.1.1 Fiber arrangement Untwisted yarn fabric Since the fibers in the yarn forming the fabric are arranged in parallel, the fiber has a large degree of freedom, so the fiber is It becomes a ribbon or flat shape after being extruded, which makes it have different characteristics from the fabric formed by traditional spinning methods 3.1.2 Appearance Due to the ribbon-like cross-section of the yarn in the fabric, the coverage coefficient of the fabric increases , so the fabric looks thick and tight, with a good fluffy feel, and the fabric quality is lighter. The luster of the untwisted yarn fabric is softer than that of the twisted yarn fabric. 3.1.3 Processing technology The untwisted yarn has no twist shrinkage, so the fabric shrinkage is lower than that of the traditional yarn. The fabric is small, which can greatly save raw materials; the dyeing performance of the untwisted yarn fabric is good, and a mercerized effect can be obtained. The fibers in untwisted yarn are exposed and can fully contact with the dye, so the dye is easy to be dyed. Twisted yarn often needs to be mercerized to make the fibers arranged more neatly to obtain good luster without twisting.Yarn does not require this treatment; the bulky effect of untwisted yarn fabrics can be used to create lighter, thicker and more comfortable fabrics. 3.1.4 Disadvantages of untwisted yarn Untwisted towels feel super soft and thick, but during use, no matter how high-end untwisted they are, there will be some lint loss. This is a shortcoming caused by the craftsmanship that is difficult to eliminate. But we can wash it with warm water before use, which can remove most of the floating hair and improve the shedding phenomenon. 3.2 Research on the wearing performance of untwisted yarn fabrics 3.2.127.8tex untwisted polyester core cotton yarn and twisted cotton yarn , The tensile properties of twisted polyester-cotton yarn have been tested and the strength of untwisted yarn is between twisted cotton yarn and polyester-cotton yarn. We know that the strength of ordinary cotton yarn is enough to provide the tension required for spinning, which shows that the strength of untwisted yarn is sufficient Provides the strength needed for weaving. 3.2.2 Performance test of untwisted yarn knitted fabric The cotton/water-soluble vinylon plied yarn knitted fabric was completed on an ordinary manual flat knitting machine. The needle number of the knitting machine is No. 14. The fabric is plain knitted fabric with a single yarn density of 28tex. , the surface density is 147g/m2. 3.2.2.1 Air permeability The air permeability experiment was conducted on the YG461 medium-pressure air permeability meter. In order to compare the air permeability of cotton knitted fabrics and untwisted yarn knitted fabrics, the two samples used were woven under the same conditions, and their yarn and fabric specifications were also the same (28tex yarn, needle number 14, plain knitted The surface density is 147g/m2). At the same time, the cotton knitted fabric is also boiled in boiling hot water for 0·5h and then dried. The average value of 10 sets of measured data is 28tex untwisted yarn 4.284mm.s-1; 28tex twisted yarn 2.609mm.s-1. It can be seen that the air permeability of untwisted yarn knitted fabric is nearly higher than that of traditional cotton knitted fabric. 1 times, thus indicating that the untwisted yarn knitted fabric has good air permeability. 3.2.2.2 Moisture absorption and quick-drying performance Cut two 12cm × 8cm rectangular pieces of cloth from the untwisted yarn knitted fabric and the cotton knitted fabric and weigh them. Number the four samples and immerse them in water for 30 minutes to ensure that they are fully infiltrated. Take them out and hold them in your hand after 0.5 hours. When they no longer drip, measure their mass with a precision physical balance and write down the corresponding data. Then, hang the sample on the rack and let it dry naturally. Then measure the quality every 10 minutes and record the data of each measurement until all four samples are dried naturally. Use the experimental data obtained to calculate the average moisture content of cotton fabrics and untwisted yarn fabrics. Moisture content = (wet weight – dry weight)/wet weight × 100%. The time moisture content is as follows.
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