What Is The Role of Printing Steaming

What is the role of steaming?

After textile printing, except for ice dyes and soluble vat dyes, general dyes must be steamed.

The purpose is to make the printed textiles complete the moisture absorption and temperature rise of the fiber and color paste film, accelerate the reduction of the dye and the dissolution on the fiber, and make the dye diffuse into the fiber and fix on the fiber.

The process conditions of steaming vary with the properties of the dye and fiber.

During the steaming process, the steam first condenses on the textile, and then the temperature of the textile rises rapidly. At the same time, the fiber absorbs moisture and swells. After the color paste absorbs water, it accelerates the full dissolution of the dye and chemical agent, which is conducive to the occurrence of chemical reactions, promotes the transfer of the dye from the color paste to the fiber, and diffuses into the fiber to produce fixed color. The main factors affecting the moisture absorption of the color paste are the temperature and relative humidity in the steamer.

The steaming equipment is selected according to the steaming process conditions, fabric properties and production scale.

For some easily deformed fabrics such as silk, loose steaming equipment should be used. For small batch production, intermittent steaming equipment can be used. For large batch production, loose continuous steaming machines such as loose bottomless long ring steaming machines can be used. Generally, there are a row of guide rollers on the upper and lower sides of the steaming machine. The fabric is dragged forward by the upper row of guide rollers. After the fabric is printed, the fabric surface carries more color paste. In order to avoid "paste", a wrap-around continuous steaming machine with the back of the fabric in contact with the guide roller can be used.

After steaming, the color paste, paste, residual chemicals and dyes on the fabric must be washed away by water, and ice dyes and reducing dyes must be boiled with soap to obtain good color and color fastness. Fabric washing and soap boiling are generally carried out on a multi-grid washing machine. The entire washing process is completed by the diffusion of dyes and the exchange of washing liquid.

The original paste in the color paste must be swollen before it can be washed away. The difficulty of washing is directly related to the properties of the paste and the heat they are subjected to during the pre-processing process. Residual dyes and chemicals diffuse into the washing liquid and are washed off the fabric under the continuous replacement of fresh washing liquid.

In order to improve the washing effect, general washing equipment should meet the following requirements and designs, namely:

① Increase the washing temperature;

② Design washing facilities with oscillation;

③ Design equipment that can force the washing liquid to penetrate the fabric;

④ Make the washing liquid on the washing machine flow back;

⑤ Increase the cloth capacity to extend the action time of the fabric in the washing liquid.

In short, the design of the washing machine should be conducive to the desorption of residual dyes and pastes to prevent the fabric from being contaminated again.

Commonly used steaming equipment includes reduction steamers and high-temperature and normal-pressure steamers mainly used for cotton and its blended fabrics, cylindrical steamers for silk fabrics, and simple steaming room equipment for the reproduction industry such as bed sheets, etc.

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