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Ten key indicators of reactive dyes

Views: 2     Author: Site Editor     Publish Time: 2021-08-19      Origin: Site


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Ten key indicators of reactive dyes


The ten parameters of reactive dye dyeing include: dyeing characteristics S, E, R, F value, migration index MI value, level dyeing factor LDF value, easy washing factor WF value, lifting power index BDI value/inorganic value, organic Value (I/O) and solubility.


The ten parameters have great guidance for the main properties of reactive dyes, such as: dye uptake, directness, reactivity, fixation rate, level dyeing, reproducibility, compatibility of mixed dyes, and color fastness.

Reactive Dyes

1. Directness

S represents the directness of the dye to the fiber, which is characterized by the adsorption rate when it is adsorbed for 30 minutes before adding alkali.


2. Reactivity

R represents the reactivity of the dye, which is characterized by the fixation rate after 5 minutes of alkali addition.


3. Exhaustion rate

E represents the exhaustion rate of dyeing, which is characterized by the final color depth and dosage ratio.


4. Fixing rate

F represents the fixation rate of the dye, which is the fixation rate of the dye measured after the dyeing is washed away from the floating color. The fixation rate is always lower than the exhaustion rate.


S and R values can describe the dyeing rate and reaction rate of reactive dyes. They are related to the dye migration and leveling properties. E and F are related to dye utilization, easy washing and fastness.


5. Migration

MI: MI=C/B*100%, where B represents the residual dye amount of the dyed fabric after the migration test, and C is the dye uptake of the white fabric after the migration test. The higher the MI value, the better the levelling property. MI value greater than 90% is a dye with good level dyeing properties.


6. Compatibility

LDF: LDF=MI×S/ELDF value greater than 70 indicates better level dyeing.


RCM: Reactive dye compatibility factor, which consists of 4 elements, S, MI, LDF and the half dyeing time T of the reactive dye in the presence of alkali.


In order to achieve a high one-time success rate, the RCM value is generally determined in the following range, S=70-80% in the neutral electrolyte, MI greater than 90%, LDF greater than 70%, and half-staining time greater than 10 minutes.


7. Easy to wash

WF: WF=1/S(EF), generally the fixation rate of reactive dyes is less than 70%, (EF) is greater than 15%, when S is greater than 75%, there are more floating colors and difficult to remove, so they cannot be used as deep colors. dyeing.


8. Lifting power

BDI: Lifting power index, also known as dyeing saturation value. To increase the depth, the amount of dye is generally increased, but the dyes with poor lifting power do not increase in depth as the amount of dye increases to a certain extent. Test method: Based on the apparent color yield of dyed fabric measured under standard chromaticity (such as 2% as the standard), the apparent color yield of dyed fabrics of each chromaticity and the standard chromaticity under the gradual increase in the amount of dye The ratio of the view to the color quantity.


9. I/O value

I/O value: People call the hydrophobic (non-polar) part of the organic substance the organic base part, and the hydrophilic (polar) part is called the inorganic essential base part. After adding up the values of different groups Then divide the sum of the polar group and non-polar group to get the value. The I/O value represents the distribution of the dye in the fiber and dye liquor. This is also a very important indicator for how to choose the three primary colors.


10. Solubility

The better the solubility of the dye, the wider the application range. There are two ways to improve the solubility: one is to add some wetting agents with special structures to make the dyes wet quickly in water, and then through the alkyl naphthalene sulfonic acid formaldehyde condensate series dispersants to make the associated molecules of the dye form a single molecule . The second method is to compound the isomers of reactive dyes.

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