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How to choose the dye?

Dyestuff selection is an important link in process design. It not only affects dye quality, but also directly affects product cost and economic benefits. The choice of dye category should generally be based on factors such as fiber raw materials, color characteristics, fastness requirements, processing costs, equipment conditions, and environmental protection requirements. The dyeing process should be determined according to the dye type, production batch, equipment conditions, production cost and other factors, and combined with the actual situation of the factory.

1. According to the nature of fiber material

The fiber raw materials that make up the fabric are the most basic basis for dye selection. Commonly used dyes for dyeing textile fibers are shown in the following table.

 

Commonly used dyes for dyeing textile fibers:

Fiber / Dye

Direct
dyes

Reactive
 dyes

Vat
dyes

Sulfur
dyes

Ice dye

indigosol
dye

Coating

Disperse
 dyes

Cationic
 dyes

Acid
dyes

Acid
mordant

Acid
complex

Neutral

Cotton

 

 

 

 

 

 

Flax

 

 

 

 

 

 

Viscose fiber

 

 

 

 

 

 

 

 

Silk

 

 

 

 

 

 

 

 

Wool

 

 

 

 

 

 

 

 

Polyester

 

 

 

 

 

 

 

 

 

 

Nylon

 

 

 

 

 

 

 

 

Acrylic

 

 

 

 

 

 

 

 

 

 

 

 

Blended or interwoven fabrics should choose appropriate dyes and processes according to the composition and content of the fibers, and try to choose the dyes that are compatible with the two fibers, so that the dyeing method and process are relatively simple.

 

If there is no suitable one, you can choose two types of dyes to dye two different fibers separately, but the process adaptability of the two types of dyes should be considered. For example, polyester-cotton blended products can be dyed with soluble vat dyes, coatings, etc., as well as disperse/reactive, disperse/ vat dyes.

 

Another example is the nylon/cotton interlaced fabric, which can be dyed with reactive dyes, or with disperse/reactive, weak acid/reactive dyes.

2.According to customer requirements

Incoming sample requirements generally include color difference, vividness, color fastness, product use, etc. For some fiber products, there are often many types of dyes applicable, but not all dyes can meet customer requirements.

 

For example, some dyes can only be dyed with a certain color; some dyes may be suitable for dyeing deep and dense colors, some dyes are only suitable for dyeing light and light colors; some dyes have good fastness, and some have poor fastness.

 

This requires us to have a sufficient understanding of the application properties of various dyes, including their chromatogram, brightness, color fastness, price, etc., and then choose the most suitable dye according to the customer's requirements for color and fastness. The application properties of commonly used dyes for cotton fabrics are shown in the following table.

 

Application performance of commonly used dyes on cotton fabrics

Performance Dye

Reactive dyes

Vat dyes

Sulfur dyes

Direct dyes

Ice dye

indigosol dye

Coating

Chromatography

Complete

Lack of scarlet

Incomplete

Complete

Lack of Green

Complete

Complete

Color Fastness

Bright

Bright

General

General

Rich Bright

Bright

Bright

Washing Fastness

Good

Good

Good

Poor

Good

Good

Good

Rubbing Fastness

Good

Good

General

Good

Poor

Good

General

Light Fastness

Good

Good

Good

General

General

Good

General

Level dyeing

Good

General

General

General

General

Good

General

Dyeing method

Simple

Simple

complex

Simple

complex

Simple

Simple

Cost

Low

litte high

Low

Low

Low

High

General

Disadvantage

Low fixing rate, not resistant to chlorine bleaching

Bad photosensitivity

Not resistant to chlorine bleaching, low wet rubbing fastness

Low wet fastness

Low wet rubbing fastness

Poor dyeing and poor photosensitivity

Low scrub fastness, poor hand feeling

Applicability

widely

widely

Deep
concentration

widely

Deep
concentration

Deep
concentration

widely

 

If the customer needs to process a batch of bright green cotton products for washing garment fabrics, the optional dyes are reactive, reducing, coatings, etc., but considering the use and cost, there is no need to choose high fastness, expensive, and complex technology. Vat dyes, the first choice should be paint, followed by reactive dyes.

3.Implement basic conditions based on process

When the dye variety is selected, the dyeing process is basically determined.

 

Therefore, when selecting dyes, process designers must consider the implementation conditions of the process, such as the adaptability of the equipment to the process, the technical literacy of the operators and the production management level, etc., to ensure that the selected dyes and processes can be implemented smoothly.

 

For example, the continuous pad dyeing machine in some factories is not suitable for dyeing with sulfur dyes (the wet steaming for a long time after the padding solution), soluble vat dyes (the acid color padding tank needs to be corrosion resistant), and some factories do not have it. High-pressure closed equipment cannot implement high-temperature and high-pressure dyeing processes for disperse dyes.

4.According to production cost

The main factors affecting production costs are the raw material costs of dyes and auxiliaries, energy consumption in the dyeing process, and management costs. The principle of dye selection is to choose low-priced, low-energy, easy-to-operate and low-pollution dyes as much as possible on the premise of meeting customer requirements for product color and fastness, which will help reduce production costs.

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