1. Raw material selection
The use of raw materials for denim fabrics is becoming wider. The choice of raw materials has broken through the cotton-based pattern, and a variety of raw material series have emerged, such as hemp cotton, ramie, spun silk, polyester, spandex, different chemical fibers, wild fibers, etc., among which there are blended chemical fiber fabrics or cross and cross Wait.
For example, the weft yarn of elastic denim fabric, the use of spandex core-spun yarn, the combination of spandex yarn and cotton yarn (such as two 29tex cotton yarns and a 7.8tex spandex yarn with a slight twist), and PBT elastic yarn.It is very good that PBT stretch yarn has the advantages of high elasticity, long-lasting strength and low cost.
The viscose yarn with a useful linear density of less than 18tex is used as raw material to make rayon imitation silk denim fabric. In addition to the appearance of ordinary thin cotton denim fabric, it also has the style of rayon fabric.
TRC denim fabric with viscose/cotton (R/C) blended chemical fiber fabric yarn as warp yarn, and polyester (T) filament or polyester/cotton (T/C) blended chemical fiber fabric yarn as weft yarn.
Denim silk woven with 48tex*48tex silk rotor yarn, 45tex hemp/cotton (55/45) blended chemical fiber fabric yarn as warp yarn, 125tex rabbit hair yarn (40%) and 107tex polyester air textured yarn (60%) The jacquard denim fabric is woven with weft yarns, which has a rich hand feeling and a strong wool style.
Hemp/cotton (55/45) blended chemical fiber fabric is used as warp yarn, and hemp/polyester (55/45) blended chemical fiber fabric is used as weft yarn. This blended chemical fiber fabric product has a rougher Comfortable, firm, and durable. Hemp/cotton (55/45) is also used as warp yarn, arranged in longitudinal stripes and interlaced with endless viscose fiber.
Colored natural cotton is used as raw material. For example, Japan has developed a colored high-end denim fabric made of natural brown cotton fiber as raw material. It is called "flesh denim fabric". The product has a natural color tone and a soft natural feeling. A new finish has been added to the service.
Denim fabrics woven from ring yarns of uneven thickness as warp yarns and rotor yarns as weft yarns have a tendency to return to the ancient times and are called "ancient denim fabrics". Or the warp and weft yarns are all made of rotor yarns with colorful effects, and mixed with slub yarns in a certain proportion in the full width of normal warp yarns to make slub denim fabrics. The fabric surface style retains the original denim fabric's unique rugged and free The texture is very popular in Europe, and it also has a "raindrop-like" effect.
Others use wild fiber (Apocynum, etc.) as raw materials.
Second, the original yarn requirements
(1) Original yarn structure
The raw yarn spun by rotor spinning is favored by the denim fabric production industry for its superior performance, gradually replacing ring bell yarn, and has made great progress.
1. Structural characteristics of rotor yarn
(1) The fibers are divided into two parts: the core and the outer layer. The cores are arranged closely, and the fibers in the outer layer are relatively loose.
(2) The fiber morphology in the yarn is complex, and the spinning yarn structure is uneven.
2. The performance of rotor yarn
(1) The uniformity is good, which is manifested by low unevenness, less details, thick knots, and neps.
(2) The strength is low, but the coefficient of variation is small, and the elongation is large.
(3) Good wear resistance.
(4) The looseness is good and the structure is full.
(5) Strong ability to resist fatigue.
(6) Few hairiness, but uneven hairiness is more severe.
(7) Coloring has good moisture absorption (very good ring dyeing effect).
(2) Raw yarn requirements
1. Quality requirements for rotor yarn
(1) The strips are uniform (including long and short segments).
(2) Less miscellaneous.
(3) It has certain strength and flexibility.
(4) No yarn defects.
(5) Less knotty.
Denim fabrics require high yarn evenness, especially high-end denim fabrics. The unevenness of the raw yarn and the slub yarn defect not only affect the strength unevenness of the warp and weft yarns, but also affect the fabric style and appearance quality of the denim fabric. It is the evenness and slub defects on the weft yarn, which threaten the appearance quality of the finished product even more. As for the evenness and slub on the warp yarn, the general slight unevenness has little effect on the appearance quality of the product. Therefore, the warp yarn evenness level can be lower than the requirement of the weft yarn.
The knots and hairiness on the warp yarn have a great influence on the color; the knots and hairiness on the weft yarn will also affect the appearance quality of the cloth surface, especially the neps and hairiness, which will cause white stars on the cloth surface and cause large Downgrade in batches.
The production of denim warp yarn is characterized by a long process flow. If the spinning yarn does not have sufficient strength and elasticity, it will cause a large number of accidental elongation and even breakage, which severely affects the smooth production of various processes. In addition, in the weaving process, a larger upper machine tension is generally adopted, which also requires higher strength and excellent elasticity of the warp yarn.