Printing and dyeing plants using reactive dyes, often to make a mistake!

　10 points of attention: operational considerations for reactive dyestuff coloring. According to the market survey, reactive dyestuff is one of the dyestuffs with many applications in the market at present. This article mainly summarizes 10 common operational misconceptions and solutions for your reference.

　　1、Why do we need to use a small amount of cold water to adjust the slurry first and the temperature of the material should not be too high?

　　(1) first with a small amount of cold water slurry purpose is to make the dye simple fully wet, if directly pour the dye into the water that is, the dye outer layer of the formation of gel, the dye particles wrapped up, so that the dye particles inside difficult to wet difficult to open, so should first use a small amount of cold water slurry, and then hot water to open.

　　(2) The temperature of the material is too high, it will cause the hydrolysis of the dyestuff and reduce the fixing rate of the dyestuff.

　　2、Why should the material be added slowly and evenly?

　　This is mainly to prevent the dyes from being dyed too fast. If we add dyes quickly at once, the dyeing rate will be too fast, which will make the outer layer of the fiber deep and the inner shallow simply cause the color flower or strip flower.

　　3、After adding dyestuff, why do we need to dye for a certain period of time (e.g. 10min) before starting to add salt?

　　Salt is a dyeing agent, when the dyeing to a certain extent, has reached saturation difficult to continue to dyeing plus salt is to break this balance, but the salt to promote dyeing before about 10-15min time to carry out, the dye to fully penetrate evenly, otherwise easy to cause strip flower, color flower.

　　4、Why do we need to add salt in parts?

　　The purpose of adding salt in parts is to promote dyeing evenly, so as not to promote dyeing too fast and cause color flowers.

　　5、After adding salt, why do we need to carry out a certain time (such as 20 minutes) to fix the color.

　　There are two main reasons: A. It is to let the salt dissolve evenly in the tank and promote dyeing fully; B. It is to let the promotion of dyeing enter the saturation of dyeing and reach the balance, then add alkali to fix the color to achieve high dyeing amount.

　　6、Why does adding alkali become "solid color"?

　　Reactive dyes plus salt only promote the dyeing effect, but the addition of alkali will stimulate the activity of reactive dyes, so that dyes and fibers in alkaline conditions to react (chemical reaction) so that the dyes are fixed in the fiber, so called "solid color" also due to this kind of solid color chemical reaction, to achieve a higher fastness. Once the solid color color flower printing is difficult to uniform.

　　7、Why should we add alkali in stages?

　　The purpose of adding in parts is to make the solid color evenly, to prevent color flowers.

　　If a one-time addition is easy to cause local residual liquid too high concentration and fiber reaction to speed up, will simply cause color flowers.

　　8、Why must we turn off the steam first when adding material?

　　a. The purpose of shutting off steam before adding material is to reduce the difference between the bars to prevent color blossoms.

　　b. The temperature on both sides of the control cylinder is more than 3℃ when heating up, and the color will be affected, more than 5℃, and more than 10℃ when stopping the machine.

　　machine for maintenance.

　　c. Some people have tested, pulling the cylinder is steam after the station turns 10-15 minutes in the cylinder before and after the temperature is basically uniform, and equal to the surface temperature, so the material, regardless of chlorine boiling to add H202 or coloring home dye salt, soda ash, should first shut down steam before adding material.

　　9、After adding alkali why ensure the process holding time?

　　Holding time should be calculated from after adding alkali, and heating up to the process holding temperature only when the holding time is calculated, only according to the process holding time cutting board, quality assurance, because the holding time is developed according to a certain amount of dyes need how much time to react to determine the laboratory is also this time proofing.

　　10, several not according to the provisions of the process cutting board caused by quality instability situation.

　　Time has not arrived "right" color cutting board.

　　Due to the problem of playing the board material weighing material problems, cloth weight bath ratio and other problems will cause color deviation, time has not arrived "right" color this abnormal situation should be reported to the team leader or technician, no matter what, shorten the process, insulation time, dye reaction is not sufficient, the color on the dye unchanged, on the uneven, no sense of fullness, fastness also become a problem.

　　Cut the board early and make up the material inaccurately.

　　Dyeing on the dye only to reach the process insulation time to be stable, the earlier the cutting board time, the greater the change, the more unstable, if the time is not to cut the board, (after boiling, practice, washing, blowing dry to send to the technician to see the color, to open a single weighing material this time, the actual insulation time of this tank cloth has been extended, at this time on the dyeing also increased, join the replenishment of this tank cloth is too deep, and again to recede shallow.)

　　Extended time cutting board, no benefit.

　　More than the insulation child for the cutting board, the dye reaction has ended, and then dyeing is useless, but will make part of the dye already on the dye re-hydrolysis.