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Common Problems And Solutions In The Dyeing Process（2）

Views: 15 Author: Edie Publish Time: 2023-08-31 Origin: Site

Common Problems And Solutions In The Dyeing Process（2）

Chemical Stain

Uneven color of the cloth surface, which shows a block of dark or light irregular color spots.

Causes

1). Fiber raw materials, fabric tissue uniformity

2). Pre-processing fabric uniformity

3). Dyeing reasons

Dye uniformity (dye migration) is poor.

Swimming shift of dyestuff during dyeing;

Dye fineness is too fine;

Unreasonable process (e.g. too fast temperature rise and fall)

4). Improper operation (such as feeding too fast, drying too fast)

5). Equipment problems

Such as disperse dyes after dyeing polyester heat shaping machine oven temperature are also easy to produce color difference and color flower, rope dyeing machine whose pump force is not enough is also easy to cause color flower.

Solutions

1) Strengthen the inspection of blank cloth.

2) According to the nature of the fiber, choose the dye with good leveling.

3) Strengthen the pretreatment to ensure the quality of semi-products.

4) Rolling rate should be even;

5) Adding leveling auxiliaries;

6) Adopt the dyestuff to reach the required fineness range;

7) Drying temperature from low to high, to avoid the dye to produce swim shift.

8) The dyeing process is reasonable and the process conditions are strictly controlled.

9) Strengthen the inspection and debugging of equipment.

Colour stains

Deeper than the cloth colour stains. The most common in the use of dispersed blue, dispersed Cuilan, dispersed red jade and other dyes on the colour system, due to the special nature of the dyes themselves, the dyes did not melt away, the heating speed and so on directly lead to colour stains.

Causes

Aggregation of dyestuff: Dyestuff aggregates are deposited on the fabric (including whitening agent aggregates).

Dyestuff tarring: dyestuff particles and surfactants coalesce at high temperature.

1、Bad pretreatment, insufficient washing

2、Use of non-ionic or anionic auxiliaries with cloud point lower than the dyeing temperature, washing is not clean.

3、Poor dissolution of surfactant

Staining of fabrics by colour precipitation: Coloured sticky substance formed on the surface of dyeing solution by improper operation or foaming of auxiliaries.

Solutions

1、Strengthen the pre-treatment of fabric

2、Strictly prevent dyestuff coagulation

Choose dyestuffs with less cohesion

Select levelling agent or dispersant with good performance.

Avoid and reduce the production of colour precipitation (chemical material specification, add diffusing agent).

Colour spots

The tiny dots with darker colour are irregularly presented on the dyed fabrics. (Including white spots)

Causes

There are also many reasons for the production of colour spots, such as white spots, which may be the reason why non-mature cotton is not dyed with dyestuffs, and may also be the reason why the solids such as soda ash and metamizan are stained on the cloth, resulting in local non-dyeing and so on.

1, Improper selection of dyes: dye particles are large or very easy to produce cohesion and colour points;

Poor dissolution of dyestuffs: undissolved dyestuffs enter the dyeing liquid and stain the fabrics and become colour spots;

3, Dyeing equipment is not clean: the tar-like substance of the dyeing vat falls down and causes colour spots;

4, Poor management (such as chemical material barrel is not clean)

5, Poor water quality: poor water quality causes dyes to condense; flocculent in the water is brought into the dyeing tank;

6, Improper control of raw materials and processing conditions

Coloured fluff or fluff melting and adhering in the burnout

Improper emulsification of softener, improper salt and alkali chemical materials

Improper process control

Solutions

1、Increase the number of dyes grinding, increase the amount of dispersant

2、Dissolve dyestuffs and auxiliaries with soft water, add co-solvent, and control proper water temperature.