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Dyeing process of acid dyes and some problems needing attention
Dec 25, 2018

When dyeing with acid dyes, the common problems are: color, color change, yellowish color, insufficient levelness, etc. In addition to the poor quality of dyes, improper process operation or inadequate handling of details are also the causes of these problems. Taking acid dyes dyeing nylon as an example, this paper discusses the dyeing process of acid dyes and the problems needing attention in production.

 

I. SOME RELATED PROBLEMS

 

1. Classification of acid dyes:

 

Strong acid bath acid dye H2SO4PH2-4

 

Weak acid bath acid dye HACPH 4-6

Neutral bath acid dye NH4ACPH6-7

 

2. Applicability of acid dyes: dyeing wool, silk and nylon in acidic or neutral formulas.

 

3. The characteristics of dyeing nylon with acid dyes (weak acid bath):

 

1) Fast dyeing and poor leveling - suitable leveling agent is required.

 

2) poor dyeing fastness (e.g. soaping fastness) - require fixing treatment (especially medium and dark varieties)

 

3) Dyeing process: 50-600C initial dyeing-1000C guarantee-water fixing treatment successively.

 

II. Dyeing process of nylon dyed with acid dyes

1. Composition of dye solution:

 

Dye X%;

 

1-3% acetic acid;

 

Leveling agent 0.3-0.5%

 

PH4 - 61=20

 

2-4% fixing agent

 

HAC0.5-2%

2. Dyeing methods: one-bath method and two-bath method (the specific operation curve is as follows)

 

1: One bath operation curve

 

PH4-6 bath ratio 1:20

 

2: Two-bath operation curve

 

Dyeing

 

(3) The prescription of fixing solution:

 

Fixing agent 2-4%

 

Ice acid 0.5-2%

PH4 - 5

 

1. The function of the additives:

 

1: Leveling agent: (e.g. ZJ-RH08 acid dyeing agent)

 

To achieve a uniform dyeing effect, excessive dosage will reduce the color bar.

 

2: Glacial acetic acid

 

Adjusting the PH value is beneficial to leveling.

 

3) Fixing agent: (ZJ-RH03 acid fixing agent)

 

Improve the dyeing fastness of acid dyes.

 

4) chemicals:

 

Refining in cold water, dissolving in hot water or boiling water, fully stirring, dissolving, diluting and filtering.

 

5) charging:

 

Attention should be paid to slow, uniform, and prevent the coloring caused by too fast feeding.


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