KN type mostly refers to the middle-temperature reactive dyes whose reactive groups are vinyl sulfones. The recommended dyeing temperature is 45～60℃, with moderate reactivity. This type of dye is basically dyed in the form of ß-hydroxyethyl sulfone sulfate. Because of its low directness to the fiber, the level dyeing and translucent dyeing properties are better at this time. When the dyeing is close to equilibrium, the dyeing temperature will rise to 60℃ and adding alkali agent, the dye will be converted into vinyl sulfone form, the directness will be greatly increased, and the fixation process will be completed faster.
The most commonly used varieties of vinyl sulfone dyes in dip dyeing are C.I.5﹟black, C.I. 21﹟Emerald blue, C.I.19﹟Brilliant blue, etc.