Dye selection is an important link in process design, which not only affects the quality of dye, but also directly relates to product cost and economic benefit. The selection of dye categories should generally be based on fiber raw materials, color characteristics, fastness requirements, processing costs, equipment conditions, environmental requirements and other factors. The determination of dyeing process should be determined according to the dye category, production batch, equipment conditions, production costs and other factors, and combined with the actual factory consideration.

1, according to the nature of fiber raw materials

The fiber raw material of fabric is the most basic basis for the selection of dyes. Table 16-1 lists the dyes commonly used for dyeing textile fibers.

Blended or interwoven materials should be based on the composition and content of the fiber to choose the appropriate dye and process, as far as possible to choose the two fibers of the common application of the dye, so that the dyeing method and process is relatively simple.

If there is no suitable, two types of dyes can be selected to dye two different fibers, but the process adaptability of the two types of dyes should be considered.

For example, polyester and cotton blended products can be dyed with soluble VAT dyes, paints, etc., and can also be dyed with disperse/reactive, disperse/VAT dyes.

Also such as brocade/cotton interwoven material, you can choose reactive dyes dyeing, you can also choose dispersion/active, weak acid/reactive dyes and other processes dyeing.

2, according to customer sample requirements

Sample requirements generally include color difference, brightness, dyeing fastness, product use, etc. For some fiber products, the applicable dye varieties are often many, but not all dyes can meet customer requirements. There are often questions about customer requirements in this area.

For example, some dyes can only dye a certain color; Some dyes may be suitable for deep color, some dyes are only suitable for light color; Some dyes have good fastness, some dyes have poor fastness, etc.

This requires us to have a sufficient understanding of the application performance of various dyes, including their chromatography, brightness, dyeing fastness, price, etc., and then choose the most appropriate dye according to the customer's requirements for color and fastness.

Table 16-2 shows the application properties of common dyes for cotton fabrics.

If the customer needs to process a batch of bright green cotton products for washing clothing fabrics, the optional dyes are active, reduction, paint, etc., but considering the use and cost, there is no need to choose high fastness, expensive, complex process of VAT dyes, and the preferred dye should be paint, followed by reactive dyes.

3, according to the basic conditions of process implementation

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 operator and the level of production management, etc., to ensure that the selected dyes and processes can be smoothly implemented.

For example, the continuous pad dyeing machine in some factories is not suitable for curing dyes (a long time of wet steaming after dipping the dye), soluble VAT dyes (acid color dipping tank must be corrosion resistant) dyeing, and some factories do not have high pressure sealing equipment, it is not possible to implement the high temperature and high pressure dyeing process of disperse dyes.

4. According to production cost

The main factors affecting the production cost are the raw material cost of dyes and auxiliaries, the energy consumption in the dyeing process, and the management cost.

The principle of dye selection is that under the premise of meeting the customer's requirements for product color and fastness, the dye with low price, low energy consumption, easy operation and small pollution should be selected as far as possible, which is conducive to reducing production costs.