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Four Properties Of Reactive Dyes
May 25, 2018

The performance of the reactive dyes have the following:

 

A, solubility,

 

Good solubility in water quality of reactive dyes goods applications. Solubility and concentration of dye solution and choose the size of the bath ratio, to join the electrolyte, the dyeing temperature and the amount of urea and other factors. Reactive dye solubility difference is bigger, can see various theories, the solubility of listed refers to the range of applications to allow the dye. Used in printing or pad dyeing of reactive dyes, should choose solubility in around 100 grams/liter varieties, require dyes dissolved completely, not cloudy, the attraction point. Hot water can accelerate the dissolve, urea solubilization, salt, sodium sulphate electrolyte can reduce the solubility of dye, etc. Reactive dyes dissolved when should not join alkali agent at the same time, in case of dye hydrolysis.

 

Method for determination of the reactive dye solubility, vacuum filtering method, spectrophotometry and filter paper spot method. Filter paper spot method is simple, suitable for factory actual use. Determination, a range of different concentration of dye solution first, at room temperature (20 ) under stirring for 10 minutes, make dye dissolves. Graduated in 1 ml of pipettes into central test solution, stirring side absorb three times. And then try learn 0.5 ml liquid and vertical drops to put in the mouth of the beaker on the filter paper, repeat. After being dried eye test fluid seepage circle, with no obvious spots before the first gear concentration in the filter paper as the solubility of the dye, expressed in grams/liter. Some of the reactive dye solution, present murky colloidal solution after cooling, drop on the filter paper can even bled, no spots exhalation, does not prevent normal use.

Second, the diffusivity

 

Diffusivity is the ability to dye mobile to the inside fiber, temperature to the spread of the dye molecules. Diffusion coefficient of dye, the reaction rate and fixation efficiency high, leveling and degree of penetration. Diffusion performance, good or bad depends on the structure and size of dye molecules, the greater the more difficult it is to spread. Big dye affinity of the fibers was fiber adsorption force strong, diffusion is difficult, usually to speed up the dye diffusion by raise the temperature. The diffusion coefficient of electrolyte is added to dyeing, dye.

 

Determination of dye diffusion performance usually by membrane method. Take glue film (pt) in distilled water, thickness of 2.4 silk before immersion, impregnation wire thickness of 4.5 after 24 hours. To determine when the film stack with a certain thickness according to need, pressure in the glass down in addition to the bubble. Then caught in the middle have two pieces of plywood of rubber washer, there was a piece of plywood in the middle there is a round hole, dye solution can only be spread through the hole in the thin film layer, will cast film immersion in the dyeing of 20 let stand for 1 hour, then remove flush, observe the dyeing liquid penetration film layers and each layer of dye colour and lustre of wheat. Diffusion layer and the half dyeing time there is a certain correlation, half dyeing time is short, the diffusion layer.

Three, direct

 

Immediacy refers to the ability of reactive dyes in dyeing liquid to be absorbed by the fiber. Low solubility of reactive dyes often direct, continuous pad dyeing and printing should choose direct low variety. Bath ratio of dyeing equipment such as rope yarn dyeing, piece dyeing and should be preferred direct dyes. Pad roll cold pad-batch dyeing method, dye solution is through the pad to the fiber, also with slightly lower direct dyes easily get levelling, less color, before and after hydrolysis dye wash easily.

Four, reaction and lively

 

The reactivity of reactive dyes, often referred to as the dye and cellulose hydroxy reaction ability strong and the weak, strong reactive dye at room temperature, under the condition of weak base namely fixation can be performed, but the reaction of the dye stability is relatively poor, easy to hydrolysis lose dyeing ability. Less reactive dye needs under the condition of the temperature and fiber bonding, or using alkali agent activate fiber yarn hydroxyl, prompt reaction dye fixation on fiber.

 

Same type reactive dye reactive is roughly same, reactive strength depends on the chemical structure of dyes active group, second is the connection between dye body with reactive group, to dye reactive also to have certain influence. In addition, affected by pH, general pH value increases, the reaction rate increases. As for temperature, is also a factor to influence reaction velocity, temperature increases, the response speed is fast. Temperature increase 10 , the reaction speed can be improved 2 ~ 3 times. Therefore, after printing, after baking and steaming, react with fiber can make dye.