Direct dye dyeing of cotton knitted fabric

The characteristics of direct dyes

1. Direct dyes are water-soluble dyes that can directly dye cellulose fibers in a neutral dye bath.

2. Complete direct dye chromatogram, convenient application, low price, poor washing fastness, and poor light fastness. Often need to use fixing agent treatment.

Dyeing properties and methods of direct dyes

1. Dyeing performance

1.1 Direct dyes are all soluble in water, and the solubility increases significantly with the increase of temperature.

1.2 The dye-promoting agents often used in direct dyeing are table salt and sodium sulfate. The brighter color can be obtained by using sodium sulfate as a dye accelerator.

1.3 Direct dyes are not resistant to hard water and must be dyed with soft water.

2. Dyeing method

2.1 Generally, it is carried out on an ordinary rope dyeing machine. The dyeing bath ratio is 1:15-30. The light-colored bath ratio is larger than the darker one.

2.2 Dyeing temperature generally adopts near-boiling point dyeing to obtain good dye migration (the so-called migration refers to the diffusion of dyes from high concentration to low concentration on the fiber) and good shade and fastness. Dyeing generally starts at room temperature (dark colors can start at 60°C-80°C).

3. Fixing treatment of direct dyes

Use cationic fixing agent to treat with fixing agent Y and fixing agent M to improve its fastness.