Dyes used in printing of polyester-cotton blended fabrics

Although there are many dyes used in the printing of polyester-cotton blended fabrics, the commonly used ones are disperse dyes and reactive dyes in the same size printing and pigment printing. 1. Disperse-reactive dye direct printing. Disperse-reactive dyestuff printing is especially suitable for medium and dark printing. It has the characteristics of complete chromatogram, bright color and simple process. However, due to the different fixing conditions of the two dyes on the two fibers, and will also interfere with the two fibers, the cotton fiber is contaminated by disperse dyes, resulting in poor color brightness and whiteness. Reactive dyes There is also the possibility of staining polyester, so dyes must be selected. (1) Dye selection: ① Selection of reactive dyes: When disperse-reactive dyes are printed in the same size, reactive dyes should be selected with good fastness, bright color, fast fixation, good stability, and less staining to polyester. Since some disperse dyes are sensitive to alkali, reactive dyes that fix color under weak alkali conditions should be selected. ②The choice of disperse dyes: In addition to the bright color and good fastness, the disperse dyes should also be considered to have less staining of cotton fibers and have certain alkali resistance and reduction resistance. For example, disperse dyes with azo structure and dyes with more nitro groups will fade or change color under the action of high temperature and alkali agents. Some disperse dyes will also undergo alkaline hydrolysis, which reduces their fastness or changes color.(2) Printing process: ① Process flow: 　 printing→drying→hot melting (180～190℃, 3～2min)→steaming→water washing→soaping→water washing→drying. Prescription: ③Operation: After the reactive dye is selected, the color paste is prepared, but the total weight cannot be matched. After the disperse dye is dissolved separately, filter it in before use, and then adjust to the total weight with the original paste or water. 2. Pigment printing. At present, there are more and more pigment printings for polyester-cotton blended fabrics. Pigment printing relies on the film formed by the binder to mechanically fix the coating on the surface of the fabric, so it is suitable for various fiber blended fabrics. The paint has the advantages of darker color, clear printing outline, simple process, etc., but due to shortcomings such as hard hand feeling and poor rubbing fastness, it is currently used in printed fabrics and is limited to line stripes and small flower shapes. The printing prescription is the same as the direct printing of the paint described above. The post-printing treatment is basically the same as direct printing with paint, and the fixing conditions are 140-160℃, 3-5min or 170℃, 1-1.5min. As the fixing temperature rises, the adhesive should be resistant to high temperature baking. The process is also the same as direct printing with paint.