The PH Value Affects The Fiber Reaction Rate

In the two-phase method, caustic soda is used as the alkali agent. The pH value is above 13. According to table 1, the reaction rate is 40 times that of soda ash. Therefore, the normal method steams for 8min and the two-phase method steams for 12s. This is the main basis for the rapid steaming of reactive dyes after two-phase printing. It can be seen that the pH value changes slightly and the reaction rate changes greatly, which directly affects the effect of dye fixation.

In order to implement steam saving, urea saving or urea free post printing steaming process, it is essential to implement on-line control of pH value.

3. Effect of pH value of dyeing bath on medium temperature reactive dyes

The uptake of reactive dyes in dip dyeing is different from that of direct dyes. The dyeing process of direct dyes is mainly the adsorption of dyes by fibers, which belongs to physical changes; The dyeing process of reactive dyes also has chemical changes, that is, there will be bonding reaction between dye cellulose and hydrolysis reaction between dye water. Therefore, when dyeing with reactive dyes, the influence of pH value of dyeing bath on dyeing results is much greater than that of direct dyes.

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