Several factors affecting the color fastness of textiles

August 30, 2019

The color fastness of textiles (referred to as color fastness) means that the dyed or printed fabric is subjected to external factors (squeeze, friction, water washing, rain, exposure, light, seawater impregnation, saliva impregnation, etc. during use or processing). The degree of fading under the influence of water stains, perspiration, etc. is an important indicator of fabric. The color fastness is good, the textile is not easy to fade during the post-processing or use; if the color fastness is poor, there will be color loss, slight color, or staining, which causes a lot of trouble.

1 Frequently asked questions about the color fastness of textiles

In daily sampling and consumer complaints, the most common textile color fastness problems are as follows:

1) The sun fastness is unqualified. During the wearing process, the parts exposed to sunlight are lighter or discolored (generally the back and shoulder parts), and the colors that are not irradiated or irradiated are not changed or lightly changed, resulting in a product with the same original color. The colors are different and can no longer be used.

2) The color fastness to washing, the color fastness to soaping and the fastness to dry cleaning are unqualified. Advanced silk clothing, wool clothing, and cotton clothing are the most prone to this problem.

3) The color fastness to rubbing is unqualified. During the use of textiles, the degree of discoloration varies with different degrees of friction in different parts of the product. For example, the tops of the shirt, the elbows of the sleeves, the collar and the underarms are the easiest to fade. In addition, the hips and knees of the pants are also easy to fade.

4) The color fastness of perspiration is unqualified. Mainly summer clothes or close-fitting underwear are faded by the impregnation of sweat when worn.

2 Factors affecting color fastness and improvement methods

Products with poor color fastness will fade during the wearing process, which will affect other clothing worn on the body, or contaminate other clothes when washing with other clothes, affecting the appearance and performance; on the other hand, the color fastness is directly related to the bad. To the health and safety of the human body. Dye molecules and heavy metal ions on products with poor color fastness may be absorbed by the skin through the skin, which may harm the skin and even harm the health of the body.

The factors affecting the color fastness of textiles are divided into internal factors and external factors. Internal factors refer to the degree of firmness of the combination of dye and fiber. External factors refer to the external force or environmental conditions imposed by external factors during use. External factors cannot be controlled, so producers must work hard to improve the color fastness of the product itself. Here are a few solutions for personal practical experience for your reference.

2.1 Selection of dyeing materials

The color fastness of a product is very important. If the choice of dyeing materials is not suitable, no matter how good the additives, even the best dyeing process, there is no way to dye high quality color fastness. Only the right dye is chosen to talk about the next step.

2.1.1 Selecting dyes according to the characteristics of the fibers Different types of dyes and fibers are combined in different forms, and the bonding bonds are also different in firmness. After the dye type is determined, the dye with high dyeing performance is selected. For example, when dyeing wool fabrics, it is also a strong acid dye. Domestically produced is not as good as dyed strong acid dyes. It is not only poor in color, but also not as strong as the latter; or it is also a domestic strong acid dye. Different dyes have different bonding fastness to wool and dyeing vividness. For example, wool dyed with weak acid dyes has higher color fastness than strong acid dyes; while cotton fabrics or regenerated cellulose fiber fabrics can use either direct dyes or reactive dyes; silk fabrics can be weakly acidic. In addition to dyes and certain reactive dyes, individual direct dyes can also be used.

2.1.2 Selecting dyes according to the color depth

After determining the major class of dyes, it is necessary to further determine which dye to use based on the color and depth of the dyed color. First, try to use a dye with a color close to the desired color. If there is a deviation, then use another dye to color. Second, look at the color fastness index of the selected dye itself. The color fastness of the dye itself is poor, and the half-level color fastness can be improved by the process; thirdly, whether the saturation of the dye dyeing can reach the depth of the desired color. If a dye with a very low dyeing rate is selected, even if it is processed to temporarily reach the desired high-depth color, the dye combination will not be strong and will fall off during use or reprocessing.

2.1.3 Selecting the dye according to the color fastness series of the dye itself

The dye fastness grade of the dye is described in the introduction of each dye. When selecting a dye, it is necessary to select the dye according to the color fastness grade required by the product, and the dyeing fastness of the color matching dyes should be similar. For example, the dyeing fastness of the dye itself can only reach 2~3 grades, even 1~2 grades. Even the best additives and dyeing processes can not dye the 4~5 grade fastness. Because the dyeing fastness of the dye mainly depends on the bonding force between the dye and the fiber. If the bond between the two is not strong, how much external force can't make them firmly bond, even if the color is improved. It can't be destroyed by external factors such as washing and friction.

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