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Dyestuff basics: chemical methods for various dyestuffs

 I. Direct dyes.




  Direct dyes have relatively good heat resistance stability, direct dyes can be added to the soda ash soft water to help dissolve, chemical material first with cold soft water to blend the dyes into a slurry, then boiling soft water to stir dissolve, heating water dilution, after cooling add water to the prescribed amount of liquid.




  Second, reactive dyes.




  This type of dyestuff is not heat-resistant, high temperature is easy to hydrolysis, it is appropriate to adopt cold soft water to mix into a slurry, and then according to the hydrolysis stability of different dyestuffs adopt the appropriate temperature of soft water dissolution, heating soft water dilution, after cooling add soft water to the prescribed liquid volume.




  Low-temperature type (X type): cold water or 30-35℃ warm water (has been basically eliminated)




  High-temperature type (K type, HE type, etc.) with 70-80 ℃ hot water




  Medium-temperature type (KN, M type) with 60-70 ℃ hot water




  90 ℃ hot water for small solubility




  III. Reduction dyes.




  The melting process of reducing dyestuff is a reduction reaction process. When melting, the temperature of melting should be determined according to the reducing conditions of the reducing agent used. Such as reducing dyes commonly used reducing agent is insurance powder, in the solution of the good use of temperature 60 ℃, the temperature is too high will lead to a large number of insurance powder decomposition.




  (1) Full bath method.




  Dye into the dye cup, add red oil and a small amount of warm soft water to mix, then add the required amount of caustic soda and insurance powder, then add soft water to the required bath amount, and restore at 55℃.




  (2) Dry vat method.




  Put the dye into the dye cup, add red oil and a small amount of warm soft water successively to mix well, then add two-thirds of the amount of caustic soda and insurance powder to make the amount of dye solution one-third of the total, to determine the temperature of dissolution according to the reducing conditions of the reducing agent used. Add the remaining caustic soda and insurance powder to the dyeing cup and add soft water to the required bath volume.




  IV. Sulfur dyes.




  Precisely weigh the required amount of dyestuff in the beaker, mix it into a slurry with cold soft water, then add the pre-dissolved sodium sulfide dye solution, boil it for 10min. heat soft water and dilute it, add soft water to the required amount of liquid after cooling.




  V. Disperse dyes.




  Temperature is too high disperse dyestuff easy to crystallize precipitation. It is appropriate to use cold soft water to adjust the slurry, then use cold soft water below 40 ℃, add soft water to the required amount of liquid.




  Six, acid dyes.




  Acidic dyes have relatively good heat resistance and stability, acidic dyestuff material, first use cold soft water to adjust the dyestuff into a slurry, then boiling soft water to stir dissolved, heated soft water dilution, after cooling, add soft water to the required amount of liquid.




  Seven, cationic dyes.




  Cationic dyes have relatively good heat resistance and stability, first use concentrated acetic acid (auxiliary solution) to mix the dyes into a slurry, and then wash boiling soft water and stir to dissolve, heat water to dilute, add soft water after cooling to the prescribed liquid volume.


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