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How to deal with polyester dyeing?

Date:Jan 26, 2021

Dyeing polyester cotton (T/C) if the polyester is dyed

How to deal with what treatment and repair?


1 、The operating process of common factories has the following two AA methods (general woven fabrics) preparation> scouring/bleaching/desizing/‥>predetermined type (180℃)>dying (T&C Side)>①drying (dewatering)-intermediate Inspection>resin processing and shaping (150-160℃)>②finished product inspection>packaging. BB method (general knitted fabric) preparation> scouring/bleaching/‥> dyeing (T&C Side)> ③drying (dehydration)-intermediate inspection>resin processing finalization (180℃)>④finished product inspection>packaging.


2、Personally suggest the processing steps as follows. First, observe the color flower phenomenon AA, which belongs to the color flower caused by the stereotyped temperature effect. ①The regularity changes from deep to shallow every 15-20 meters. ②There are bands of deep or light color in the left, center and right direction. BB belongs to the heavy metals in water quality caused by the influence of heavy metals. Iron ions are the most common ones, which are full or partial yellowing. CC category belongs to general dyeing and finishing.


3、How to determine if it is a problem with polyester T (T side) The problem cloth (fault cloth) is dissolved with sulfuric acid, and the color is still seen after the cotton is dissolved.

Tiankun chem fabric for dyeding 17


4、Correction method A is aimed at the discoloration caused by the stereotyped temperature effect of type A:


The intermediate inspection found the corrective method: re-order type>Equal dyeing.


Finished product inspection found the corrective method: re-ordering> removing resin> even dyeing. B For the coloring caused by the influence of heavy metals in the water quality of Category B: Treat with 1g oxalic acid per liter at 60°C for 20 minutes. C is for the general dyeing and finishing of category C to cause discoloration:


In the operation process of Method A, it was found that the correction method was dyed in "①drying (dehydration)-intermediate inspection".


In the operation process of Method A, it was found in "②Finished Product Inspection" that the correction method was to remove resin>leveling.


In the operation process of Method B, it was found that the correction method was evenly stained in "③Drying (dehydration) intermediate inspection".


In the operation process of Method B, it was found in "④ Finished Product Inspection" that the corrective method was Resin Rejection>Equalization Dyeing or Re-ordering>Resin Rejection>Equalization dyeing.


5、The reasons for the different processes were discovered only after the resin processing was completed, and the correction method should be the process of removing the resin first.


6、The process of reshaping occurs when A is bad and B resin is processed at the same time (when there is a risk of bad shaping)


7、Process operation content ★Resin-reducing surfactant 1g/l Caustic alkali (NaOH) 1-2g/l 80-90℃×20 minutes ★Re-order type (see note 1) 180℃×40 seconds in the setting machine to redo ★ Both Dyeing (Note 2) heating curve: 20-130℃ heating up 2-3℃/130℃ per minute×40-60 minutes>cooling>reducing detergent dosage: leveling agent 2-4g/l PH control: glacial acetic acid + acetic acid Sodium (PH control 3.3-5.5 according to current factory regulations)

Dye dosage:


●Liquor ratio 1:20-30% of the original dye formula (as explained below)


●3% of the original dye formula below 1:10 bath ratio


●The so-called 5% of the original dye formula means for example:


If: Y 1.2% → Y 1.2%×0.05= 0.06% R 0.8% → R 0.8%×0.05= 0.04% B 1.5% → B 1.5%×0.05= 0.075% reduction washing (according to current factory regulations).


8、postscript


●In the above-mentioned "with oxalic acid 1g/l 60℃×20min", "reducing resin>leveling", you must first do a mini-level test in the laboratory to prove the effectiveness; when leveling, the necessary amount of dye should be added, Also calculate the amount of dye to maintain the residual liquid is 3%? 5%? still is? % So and so, you seem to know quickly before the scene, the clear fairy?


●Calibration of setting machine; selection of additives; it is not the topic of this discussion.


●Color flower phenomenon The color flower caused by the setting temperature effect ①It is very regular from dark to light every 15-20 meters. ②There is a strip of color deep or light in the left, middle and right direction, and the sublimation of the dye is poor, plus the temperature of the setting machine If the control is not good, the allowable deviation should be 3℃ (±1.5℃), otherwise the temperature of the setting machine will float, such as 180℃!


After a while, the temperature will slowly rise at 175℃ to 180℃ and then float to 185℃, →180℃→175℃ keep floating and change, then the low sublimation fastness you use is different at 175℃ and the ratio of sublimation at 185℃; Therefore, there is a phenomenon that the regularity changes from deep to shallow every 15-20 meters. From the perspective of the inspector, the so-called "page difference" and "horse difference" are seen.



Note 1: Poor stereotyping → reasons for reshaping


●The highest temperature of synthetic fiber in the cloth process (including pre-sizing or resin processing and setting) will affect the arrangement of fiber molecules. The molecular arrangement of polyester is the most neat at 180°C (Nylon is 190°C). The allowable deviation of the setting temperature is How to control the temperature at 3°C (±1.5°C) is extremely important.


●How to control the temperature: ①The use of an excellent setting machine is a necessary condition. ②The hot oil of the oil boiler must be well controlled to prevent the temperature of the setting machine from floating. (It is very important to control the oil temperature at 180+30=210±5℃. Some people have poor performance of the oil boiler and often 180+50=230±5℃ can easily cause temperature floating).


Note 2: Even dyeing


●The general principle of the leveling agent is to enclose the dye clusters. Due to the expansion of the fiber molecular gap at high temperature, the dyes fixed in the molecular gap are rapidly moved in the molecular gap of each fiber through the leveling agent. Therefore, the principle of level dyeing has added the effect of "decolorization" and the tendency of "dye agglomeration"; a good leveling agent needs to test the effect of "decolorization" and "dye agglomeration" in addition to the leveling power. High and low.


●The other leveling agent belongs to the carrier type. The principle of these additives is different from the above. It expands and increases the gap between the fibers. No matter the concentration is high or low, the dye is removed, and then the dye is renewed. Run back to the molecular gaps in different regions to achieve the goal of equalization. The carrier itself is not soluble in water, and it relies on its surfactant as a medium to dissolve in water; bad surfactants will separate when exposed to high temperatures, causing the carrier body to become The main body of the carrier agent (Carrier) that is oily and does not have a high boiling point will evaporate. Therefore, it will condense like rain and fall on the cloth surface to cause color spots (Carrier Spot) and lose all dyeing power. This dye-directing agent (Carrier) main type leveling agent will have the effect of "decoloring" and the tendency of "dye agglomeration", and the basic properties of it must be mastered before use.


●The average dyeing power at 135-140℃ is more than 5 times higher than 130℃, which is a good working method.

★But whether the dyeing machine can withstand such a high temperature, the first thing to start (must be appraised by experts). ★Whether the leveling agent is resistant to higher 135-140℃ must be confirmed first.

★The leveling time can be reduced by at least 20 minutes at 130℃.


Note 3: Reducing washing is not acceptable for most of the T/C cloths, because the T/C cotton has been colored, so it should be washed strongly, otherwise the sulphur powder will decolor the cotton dye; if it is pure polyester, it can be dyed and repaired in the reducing washing mode. Of course, the first time dyeing T before coloring can be reductive washing, because the cotton (C Side) has not been dyed at that time, and reductive washing can remove the pollution of disperse dyes on cotton.