Common Steps in Printing And Dyeing

Refining

The wax on the cotton fabric is not easy to interact with caustic soda, and it must be removed by emulsifying it with an emulsifier (soap). The emulsification should be carried out in an appropriate pH range.

Removal of silk sericin should be refined by soap alkali, but the alkalinity should not be too high, otherwise it will affect the feel and gloss. The suitable pH for silk refining is 9.5~10.5. The applications of real silk in home textiles include headscarves, handkerchiefs, bedding, silk batik (tie-dye), and decorative accessories (such as tassels and colorful ears).

After being carbonized, wool should undergo alkaline scouring to remove fat, but wool is a protein fiber. In order to prevent damage to amino acid structure and prevent rough hand feeling, the scouring pH value should be controlled. The pH value is generally controlled at 10~10.5. Wool is an important raw material for home textiles such as hand-knitted carpets, blankets, and artistic wall hangings. In recent years, the use of wool can be made into bedding, which has opened up new ways for wool in the field of home textiles.

The alkali reduction of polyester fabric is an important production process of polyester printed silk scarves. The key to the alkali reduction process is the control of the concentration of caustic soda. If the alkali concentration is too low, the effect of imitating silk is not good, and the drape is not obvious; if the alkali concentration is too high, the strength of the fabric will be damaged and cracks will occur.

Bleaching aspect

Hydrogen peroxide is a commonly used bleaching agent for cotton bleaching. The optimum pH value for bleaching is 10.5~11. At this pH value, hydrogen peroxide can slowly decompose, play an oxidative bleaching effect, remove the pigment on cotton fabrics, and will not cause serious cellulose fiber strength. decline.

For sodium hypochlorite bleaching, the pH value should be controlled at 8.5~10, and for sodium chlorite bleaching, the pH value should be controlled at 3.5~4. However, these two bleaching agents can cause adsorbable organic halide (AOX) problems, so they are gradually eliminated .

After finishing

Fluorescent whitening: Cotton cloth is fluorescently whitened, and the pH value is generally slightly alkaline, and the pH value is generally 8-9; for polyester fluorescent whitening, the pH value is required to be slightly acidic, and the pH value is generally 5-6.

Anti-wrinkle and non-iron finishing: Tartaric acid and magnesium chloride are often added as catalysts in the anti-wrinkle and non-iron finishing liquid. Tartaric acid is an acidic substance, and magnesium chloride is heated to decompose acidic hydrogen chloride with catalytic effect. The presence of these acidic substances not only affects the strength of the cellulose fiber fabric, but also causes the pH of the fabric to drop. After anti-wrinkle and non-iron finishing, it is generally not washed in water.

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