The color of vat dyes has the characteristics of a complete series from yellow to black, from bright colors to general colors. Its biggest feature is that the intermediate colors are in the majority. These intermediate colors are basically a single component with good dyeing reproducibility, especially the green, olive green, flesh-colored, brown and gray series. For example, green reactive dyes are generally mixed with yellow and emerald blue reactive dyes. In order to combine reactive dyes with different dyeing properties, control during dyeing is very important. Among the vat dyes, there are several green varieties with a single structure, which can not only meet different needs, but also have excellent dyeing reproducibility compared with reactive dyes.
At present, various composite fastnesses based on light fastness of cotton fabrics, such as sweat-light fastness, sweat-light-washing fastness, sweat-light-rubbing fastness, etc., are increasingly required, especially Light color. Compared with other types of cotton dyes, vat dyes have great advantages, so they are very suitable for dyeing and printing work clothes, summer clothing, sportswear, overcoats, curtains, and furniture covers.
Compared with reactive dyes, vat dyes also have excellent chlorine fastness (Table 4), whether it is chlorine water (20mg/kg) or chlorine bleach (500mg/kg); Table 3 also shows vat dyes It has excellent washing fastness, etc., so vat dyes are suitable for the occasions where chlorine disinfection and washing resistance are required, such as the printing and dyeing of fabrics, beddings, outer covers, bed sheets, clothes, etc., especially for hotels and hospitals. For products that require multiple washing treatments, the advantages of using vat dyes are more obvious. In addition, vat dyes are also very suitable for the dyeing and printing of textiles that require the highest level of wet fastness, such as ground dyeing with reactive dyes and textiles with vat dyes for discharge printing.
Vat dyes have very little discoloration to general resin finishing. In recent years, functional processes that change the physical properties of fibers, such as shape memory processing, deodorization processing, antibacterial processing, etc., have good stability. Moreover, vat dyes have more stable variability over time than reactive dyes.
One-bath dyeing of polyester/cotton, nylon/cotton, vinyl/cotton and other blended fabrics with the same color is more and more popular in the printing and dyeing industry. Vat dyes have the characteristics of homochromatic dyeing and are suitable for one-bath continuous dyeing, printing and dip dyeing of these blended fabrics. These dyed fabrics can be used to make school uniforms, uniforms, moisture-permeable coats and special textiles, especially military uniforms and combat uniforms (such as camouflage uniforms), and have a variety of excellent color fastness and infrared resistance.
This feature of vat dyes can be used to produce high-grade textiles for reactive dyes and vat dyes for anti-pull printing, groundless dyeing of polyester-cotton knitted fabrics (liquid flow dyeing machine), and first dyeing process for polyester-cotton blended colored fabrics (cheese yarn) Dyeing) and high fastness printing and dyeing of polyester/cotton blended fabrics (using URS method, that is, ultra-high-speed steaming method).
Fabrics dyed with vat dyes can show natural plant tones and European style features on the basis of coarse tones. For example, the dyed fabrics directly printed with indigo and vat dyes are subjected to various washing treatments (stone washing, bleaching, etc.), which can be made into textiles with extremely clear and natural plant tones. In summary, compared with other cotton dyes, vat dyes have a series of remarkable characteristics, especially reflected in the fastness performance. Therefore, vat dyes are still a class of cotton dyes worthy of attention.
Dyeing cotton fabrics with vat dyes mainly adopts the dip dyeing process, and depending on the processing volume, a cheese dyeing machine or a beam dyeing machine can be used. In recent years, in order to adapt to the high quality of cotton knitted fabrics, liquid flow dyeing machines have also been selected. In addition, in response to the requirements of small batches and rapid processing, garment dyeing will increase.
The vat dye suspension pad steaming process is used for continuous dyeing, which is suitable for the processing of large quantities of fabrics such as work clothes, coats and bedding; while the jig dyeing is suitable for small batches; it is especially suitable for wide fabrics and can be used for thick fabrics such as tents. Maximum effectiveness.
The most common method of vat dye printing is one-phase printing with potassium carbonate and anti-migration agent. A high-end printed textile that is very popular in Europe, the United States, and Japan is printed cotton fabric that is dyed with reactive dyes for ground dyeing and vat dyes for color discharge. In addition. The UPS method for mass processing uses two-phase printing, which is most suitable for direct printing on outer covers and covers.