Denim Fabric Knowledge: Introduction to the Types and Characteristics of Denim Fabrics

Abstract: This paper will focus on the types of jeans fabrics and the characteristics of all kinds of jeans fabrics. At present, the popular types of denim fabrics are mainly ring spun denim, warp and weft slub denim, super indigo dyed denim, multi-color denim and weft elastic denim. Here we share a summary and introduction one by one.Since the late 1970s, denim has developed greatly in China for many times. At present, the annual output capacity is estimated to be more than 1.5 billion square meters. It has become an important producer of denim in the world. A large number of more advanced denim and denim garment enterprises have basically been in line with the international standard in terms of quality and variety, which has preliminarily reversed the concept that China's denim products belong to "low-grade products" in the international market.

Although the development and production of denim products in China started relatively late, it has a high starting level. It has more advanced equipment such as air spinning, automatic winding, ball warp dyeing, shuttleless loom (a large number of rapier, followed by sheet shuttle, and then air jet), heavy pre shrinking finishing machine, which has created good conditions for the development of denim varieties and improving the quality level. However, for a long time, some equipment with excellent performance and complete functions, such as electronic dobby, multi-color, uneven coiling, rapid variety change and unmanned operation of rapier loom, have not attracted enough attention, resulting in functional waste. This situation needs to be solved urgently, so as to better serve the development of varieties, improve quality and labor productivity.

At present, the popular denim fabric varieties at home and abroad are mainly ring spun denim, warp and weft slub denim, super indigo dyed denim, chromatic, multi-color denim and weft elastic denim.Ring spun denim of denim fabric

With the development and application of new process equipment such as ring spinning high speed, large winding, fine winding and knot free yarn, the shortcomings of coarse count yarn, such as short spinning length, low production efficiency and many knots, have been solved. The situation that denim yarn is replaced by rotor yarn is changing rapidly, and ring spinning yarn has a great potential to make a comeback. Because ring spun denim is superior to air spun yarn in some properties, such as hand feel, drapability, tear strength, etc., and because people return to nature psychologically and pursue the influence of the original developed denim style, the more important reason is that the surface of ring spun denim clothing will show a hazy bamboo knot style after grinding and washing, It is in line with the personalized needs of today's jeans. In addition, slub yarn jeans are very popular in the market, and ring slub can spin short and dense slubs, which also promotes the development momentum of ring spun denim.

Slub denim of denim fabric

When slubby yarns with different yarn numbers, slubby thicknesses (ratio to base yarn), slubby lengths and pitches are designed, slubby yarns are equipped in single warp or single weft direction and both warp and weft directions, and are properly proportioned and arranged with normal yarns of the same or different numbers, a variety of slubby denim can be produced, After washing and processing, various hazy or clear strip and grid style jeans can be formed, which is welcomed by consumers with personalized needs. Early slub denim almost used ring slub yarn. Because it can spin slub yarn with short length, small pitch and relatively large density, it is easy to form a dense decorative effect on the cloth surface, and mainly warp slub. With the development of market consumption demand, warp and weft two-way slub denim is popular at present, especially the two-way slub denim products with weft elasticity, which are very popular in domestic and foreign markets. As long as the organizational structure of some varieties is well designed, a single variety of ring spun yarn can be used in warp direction and slub yarn with an appropriate proportion in weft direction, which can also achieve the effect of warp and weft two-way slub jeans.

Weft elastic denim of denim fabric

With the adoption of spandex elastic silk, the variety of jeans has developed to a new field, which can make jeans close and comfortable, and then match with bamboo knots or different colors to make jeans products more suitable for fashionable and personalized consumption needs, so they have great development potential. At present, elastic denim is mostly weft elastic, and the elastic elongation is generally 20% 40%. The elastic elongation depends on the fabric organization design. The smaller the warp and weft organization tightness on the loom, the greater the elasticity. On the contrary, under the condition of fixed warp organization tightness, the greater the weft elastic yarn tightness, the smaller the elasticity and the weft tightness to a certain extent, There may even be a loss of elasticity. In addition, the prominent problem of elastic denim is that the weft shrinkage is too large, generally more than 10%, and even more than 20% in some cases. The instability of cloth width brings great difficulties to garment production. The first solution is not to make the elastic extension too large in product design, which is generally 20% 30%, that is, maintain a certain warp and weft tissue tightness, and appropriately increase the tension in pre shrinkage finishing to make the cloth width shrink greatly, so as to obtain a lower residual shrinkage in weft direction of finished cloth; Another solution is to heat set the elastic denim after pre shrinking, so as to obtain a more uniform cloth width and a more stable and low weft shrinkage, so as to meet the requirements of garment processing and production.

Special color denim of denim fabric

Because the clothes made of super indigo dyed or extra deep indigo dyed denim can obtain the special effect of rich and bright color after grinding and processing, they are widely welcomed by consumers. "Super indigo" dyed denim has two characteristics: the dyeing depth is very deep and the color fastness to grinding is very good. The former refers to the amount of indigo dye dyed on the yarn per unit weight (generally expressed as% of the dry weight of the yarn, referred to as the dyeing depth%). For example, the indigo dyeing depth of conventional denim warp yarn is 1% 3%, while the "super indigo" dyeing depth needs to reach more than 4%, which can be called super indigo or extra deep indigo. The latter refers to that the "super indigo" dyed jeans need to undergo repeated grinding and washing for more than 3 hours, and its color can still reach or exceed the color depth of conventional dyed denim without grinding and washing, and its color light is much brighter than that of conventional dyed denim. For the abrasion color fastness of indigo dyed denim, its essence depends on the core penetration of the dye to the yarn, rather than the abrasion fastness of the dye itself (the wet abrasion fastness of Indigo is only grade 1), that is, the better the core penetration, the better the abrasion color fastness.

The so-called "fast washing process of indigo dyeing" in the past is actually to deliberately make the core penetration of indigo dye to the fiber very shallow in the process of yarn dyeing. In this way, when jeans are ground and washed, after a very thin layer of dye on the yarn surface is ground off, more white yarn cores are exposed, which makes the color fade quickly, so as to achieve the effect of fading immediately after grinding and washing in a short time. On the contrary, the "super indigo" dyeing process requires a particularly good degree of dye core penetration, so that jeans can obtain both deep and bright color after grinding and washing.

Because the dyeing depth of "super indigo" dyed denim products is more than 60% higher than that of conventional denim dyeing, the indigo concentration of the dyeing solution will also increase exponentially, even up to 3 4G / L, so it is possible to obtain a deeper color. In this way, the viscosity of the dye solution increases and the fluidity becomes poor, which affects the permeability of the dye leuco, reduces the abrasion color fastness of denim, and can not meet the demand for the final depth of garment production. Therefore, some enterprises adopt the design of increasing the dyeing depth again, so that the indigo concentration of the dyeing solution increases again, and the permeability becomes worse. In this way, a vicious circle is formed, and the requirements of "super indigo" color are still not met. The higher the indigo concentration in the dye solution, the heavier the red light of the dye and the darker the color, so there is no "super indigo" effect. Therefore, at present, many production plants have or are preparing to transform the dyeing and sizing equipment to solve this problem by increasing the number of dyeing passes. For example, if the number of dyeing passes is increased to 8 or even 10, it will not only increase the investment cost, dye and chemical consumption, increase the difficulty of operation, but also increase the pollution to the environment. The better way to solve this contradiction is to appropriately reduce the proportion and dosage of insurance powder or caustic soda, especially the control of caustic soda dosage, so that the pH value of dyeing solution is stable between 11 12, the dye uptake is the highest and the color is stable, and at the same time, appropriately reduce the dyeing tension of warp pieces, so as to obtain a better "super indigo" dyeing effect.

Indigo basedColored denim of jeans fabric

In order to increase the color and light changes of indigo cowboy varieties, various colored cowboy varieties are very popular at present. For example, indigo dyeing sulfur black, indigo dyeing sulfur grass green, sulfur black green, sulfur blue, etc. to meet the personalized needs of the market. At the same time, denim manufacturers have their own patented new denim varieties to improve the competitiveness of the market. In this regard, it should be noted that the concentration of mother liquor should be controlled as much as possible to prevent excessive overflow of dye liquor from causing dye waste and expanding environmental pollution.

Color (color) denim of jeans fabric

There are mainly brominated indigo (commonly known as emerald blue in the market) denim and sulfur black denim, coffee, emerald green, gray, khaki and sulfur blue denim colored with sulfur dyes, and a small amount of bright red, peach and imperial denim dyed with naftal dyes or reactive dyes. Although the production batch is small, the market demand is urgent and often can not meet the demand. The main problem is that the color and luster is not stable enough, the importance of dyeing is also poor, and the garment manufacturers are not satisfied. This is related to the small production batch and too many color varieties, but it is difficult to produce color varieties by the dyeing pulp combine, which also has a certain impact, such as large consumption, high cost, and difficult sewage treatment. The first solution is to reduce the number of color matching as much as possible in the design, adopt two color matching as much as possible, no more than three color matching at most, or use other more stable dye varieties to replace, so as to adapt to the production characteristics of the dyeing pulp online table and obtain a more stable dyeing effect; Second, the more thorough solution is to adopt the production process route of yarn high-capacity dyeing and warping in yarn dyed weaving factory to produce multi-color denim.