Jeans are clothes that can be worn all the year round. How to distinguish different types of denim (denim fabric): first, according to the thickness of denim, it can be divided into 4.5 A, 6 A, 8 A, 10 A, 11 A, 12 A, 13.5 a, 14.5 a, etc., 4.5 A is very thin, which is often used to make summer women's vest, sleeveless shirt, etc., while 14.5 A is already very thick, which is used to make men's cotton padded jacket in winter sure. Most of us wear jeans ranging from ann-12 to ann-8.
In terms of denim fabric types, it can be divided into plain, twill, herringbone, interwoven, slub, dark, and flocked denim.
In terms of ingredients, denim combed and combed, 100% cotton, Lycra, cotton / ramie blended, Tencel.
At present, the most popular denim varieties at home and abroad are ring spun denim, warp and weft slubby denim, super indigo dyed denim, register color denim, assorted color denim and weft elastic denim.
Ring spun denim
With the development and application of ring spinning high-speed, large package, fine winding, non knot yarn and other new technology and equipment, 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 spun yarn is changing rapidly, and ring spun yarn is likely to make a comeback. Because ring spun denim is superior to rotor spun yarn in some properties, such as handle, drapability, tear strength, etc., and also because of people's psychological return to nature, the pursuit of the original development of the influence of denim style, the more important reason is that ring spun denim after grinding and processing, the surface will show a hazy slubby style, which is in line with the personalized needs of today's denim 。 In addition, slub yarn jeans are very popular in the market, and ring slub can be spun into short and dense slub, which also promotes the development trend of ring spun denim.
Slub denim
When slubby yarns with different yarn sizes, slub coarseness (ratio to base yarn), slub length and pitch are designed, slubby yarns with single warp or single weft direction and both warp and weft directions are equipped with slubby yarns. When the slubby yarns are properly proportioned and arranged with the normal yarns of the same or different sizes, a variety of slub denim can be produced Stripe style denim is welcomed by consumers with personalized needs. The early slubby denim was almost made of ring spun slubby yarn. Because it could spin slubby yarn with short length, small pitch and relatively high density, it was easy to form a dense decorative effect on the fabric surface, and the warp slubby yarn was the main one. With the development of market demand, warp weft bi-directional slub denim is popular, especially weft elastic bi-directional slub denim products, which are very popular at home and abroad. However, as long as the weave structure of some varieties is well designed, single ring spun yarn can be used in warp direction and slub yarn in proper proportion in weft direction, which can also achieve the effect of bi-directional slub denim.
Weft elastic denim
With the adoption of spandex elastic yarn, denim varieties have developed into a new field, which can make denim fit and comfortable, and match with slub or different colors and colors to make denim products more suitable for fashion and personalized consumption demand, so it has great development potential. At present, most of the elastic denim is weft elastic, and the elastic elongation is generally between 20% and 40%. The elastic elongation depends on the weave design of the fabric. The smaller the warp and weft weave tightness is, the greater the elasticity is. On the contrary, under the condition of fixed warp weave tightness, the greater the weft elastic yarn tightness is, the smaller the elasticity will be, and the weft tightness will reach a certain degree, and even there will be loss Inelastic condition. In addition, the outstanding problem of elastic denim fabric is that the weft shrinkage is too large, generally more than 10%, and some even as high as 20%. The instability of fabric brings great difficulties to garment production. One of the solutions is not to make the elastic stretch too large in product design, generally 20% - 30%, that is, to maintain a certain degree of warp and weft organization tightness, and to take appropriate measures to increase the tension in pre shrinkage finishing, so that the fabric has a larger shrinkage, so as to obtain a lower residual shrinkage of finished fabric in weft direction. Another solution is elastic shrinkage In this way, uniform cloth width and stable and low weft shrinkage can be obtained by heat setting treatment after preshrunk finishing of denim, which can meet the requirements of garment processing and production.
Special denim
As the garment made of super indigo dyeing or extra deep indigo dyeing denim can obtain the special effect of bright and bright color after being ground and washed, it is widely welcomed by consumers. "Super indigo" dyeing denim has two characteristics: deep dyeing depth and excellent color fastness to washing. The former refers to the amount of indigo dye on the unit weight yarn (generally expressed as% of the dry weight of the yarn, referred to as dyeing depth%). For example, the conventional denim warp indigo dyeing depth is 1% - 3%, while the "super indigo" dyeing depth needs to reach more than 4%, which can be called super indigo or super indigo. The latter means that the denim dyed with "super indigo" needs to be repeatedly washed for more than 3 hours, and its color can still reach or exceed the color depth of the conventional dyed denim without scouring, and its shade is much more bright and bright than that of the conventional dyed denim. For indigo dyed denim, the color fastness to scouring is essentially determined by the penetration degree of dye to yarn, rather than the scouring fastness of dye itself (Indigo wet grinding fastness is only grade 1), that is, the better the core penetration degree is, the better the color fastness to scouring is.
In the past, the so-called "fast washing process of indigo dyeing" in the past was actually to make the indigo dye penetrate the core of the fiber slightly during the yarn dyeing process. In this way, when the denim clothing is milled, the very thin layer of dye on the surface of the yarn is removed, and more white yarn cores are exposed, which makes the color fade quickly, so as to achieve the effect of fading immediately after a short time of scouring. On the contrary, "super indigo" dyeing process, on the other hand, requires the dye to penetrate the core very well, so that the denim garment can obtain a deep and bright color after being ground and washed.
As the dyeing depth of denim products dyed by "super indigo" is more than 60% higher than that of conventional denim dyeing, the concentration of indigo in the dyeing solution will be doubled, even reaching 3-4g / L, so it is possible to obtain a deeper color. In this way, the viscosity of dye solution increases and the fluidity deteriorates, which affects the penetrability of dye leucomer, reduces the color fastness of denim to scouring, and fails to meet the requirements of garment production for final depth. Therefore, some enterprises take the design of increasing the dyeing depth again, so that the concentration of indigo in the dyeing solution increases again, and the permeability becomes worse, thus forming a vicious cycle, which still fails to meet the requirements of "super indigo" color. The higher the concentration of indigo in the dye solution, the heavier the red light and the darker the color. There is no "super indigo" effect. Therefore, many factories have already or are preparing to reform 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, the consumption of dyes and chemicals, increase the difficulty of operation, but also increase the environmental pollution. A better way to solve this contradiction is to reduce the proportion and dosage of sodium hydrosulfite or caustic soda properly, especially the control of caustic soda dosage, so that the pH value of the dye solution is stable between 11 and 12, the dye uptake is the highest and the color is stable, and the dyeing tension of the warp piece is reduced properly, so as to obtain a better "super indigo" dyeing effect.
Denim with indigo as base color
In order to increase the color and shade changes of indigo jeans, various kinds of color coated jeans are very popular at present. For example, indigo over dyeing sulfur black, indigo dyeing sulfur grass green, sulfur black green, sulfur blue and so on, to meet the personalized needs of the market. At the same time, denim manufacturers have their own patent features of new varieties of jeans, to improve the competitiveness of the market. It should be noted that the concentration of the mother liquor should be controlled as much as possible to prevent the excessive overflow of dyeing liquor, which will cause waste of dyes and increase the pollution to the environment.
Color denim
There are mainly brominated indigo (commonly known as turquoise blue) denim and sulfur black denim, coffee, emerald, gray, khaki, sulfurized blue denim with sulfurized dyes, and a small amount of bright red, peach and Feige denim dyed with nafto or reactive dyes. Although the production batch is not large, the market demand is urgent and often can not meet the needs. The main problems are that the color and luster are not stable enough, the importance of dyeing is poor, and the garment manufacturers are not satisfied. Of course, this is related to the small production batch and too many color varieties. However, it is difficult to produce varieties of various colors by dyeing and sizing combined machine, with high consumption and high cost, and it is difficult to treat sewage. The first solution is to reduce the number of color matching as far as possible, to use two color matching, no more than three color matching, or to use other stable dyes to replace, so as to adapt to the production characteristics of the dyeing and sizing machine, and obtain a more stable dyeing effect. The other is to adopt the production process route of yarn dyeing with large capacity and slitting and warping in yarn dyeing factory What color denim is ideal.
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