Dry goods sharing - the main factors that affect the color fastness of textiles

1. Frequently Asked Questions about Textile Fastness

In daily sampling and consumer complaints, the most common textile color fastness issues are the following:

1) The fastness to sunlight is not acceptable. During the wearing process of coat garments, the parts with more sunlight are lightened or discolored (usually the back and shoulder parts), and the areas where there is no irradiation or less irradiation have the same or no change in color, resulting in a uniform color of the original product. The shades of color are different and can no longer be used.

2) Color fastness to washing, color fastness to soaping and color fastness to dry cleaning are not acceptable. High-grade silk clothing, wool garments, and pure cotton garments are the most vulnerable to this problem.

3) The color fastness to rubbing is not qualified. During the use of textiles, the degree of discoloration is different because different parts of the product are subjected to different levels of friction. For example, the coat, elbow sleeves, collar and armpits are the most likely to fade. In addition, the hips and knees of pants are also easy to fade.

4) Perspiration fastness is not acceptable. It is mainly summer clothing or close-fitting underwear that fades when sweat is soaked.

2. Factors that affect color fastness and methods of improvement

Products with poor color fastness fade during wearing may affect other garments worn on the wearer, or contaminate other garments when washing with other garments, affecting appearance and performance; on the other hand, good and bad color fastness is also directly related 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 human body to damage the skin and even cause harm to health.

The factors that affect the color fastness of textiles are internal factors and external factors. Internal factors refer to the degree of firmness of dyes and fibers, and external factors refer to external forces or environmental conditions provided by external factors during the use of the product. External factors cannot be controlled, so producers must strive to improve the product's color fastness. Here are some solutions to personal practical experience for your reference.

2.1 Selection of dyes

The color fastness of a product, the choice of dyestuffs is very important. If the choice of dyestuffs is not suitable, no matter how good the auxiliaries or even the best dyeing techniques are, there is no way to dye them with high quality color fastness. Only by choosing the right dye can we talk about the next step.

2.1.1 Selecting Dyes According to Fiber Properties

Different types of dyes have different combinations with fibers, and the bond strength is also different. After the type of dye is determined, dyes with high dyeability are selected. For example, when dyeing wool fabrics, the same is a strong acid dye, domestically produced dyestuffs are not as good as imported strong acid dyes, not only the color is not good, the firmness of the combination is not as good as the latter, or the domestically produced strong acid dyes, Different dyes and wools have different combinations of fastness and dyeing brightness. For example, dyeing wool yarns with weak acid dyes has higher color fastness than strong acid dyes; while pure cotton fabrics or regenerated cellulose fiber fabrics can use either direct dyes or reactive dyes; silk fabrics can use weakly acidic dyes. Besides dyes, some reactive dyes, individual direct dyes can also be used.

2.1.2 Select dye according to the color depth

After determining the major classes of dyes, it is necessary to further determine which dyes to use based on the color shade and depth of the dyed color. First, try to use a dye that has similar color shade to the desired color. If there is any deviation, use another dye to color. Second, look at the color fastness index of the selected dye. The color fastness of the dye itself is poor, and the half-color fastness can be improved at most through the process. Thirdly, it can be seen whether the saturation of the dye uptake can reach the required color depth. If a dye with a very low dyeing rate is selected, even if the desired high depth color is temporarily obtained after processing, the dyestuffs will not be firmly bonded and will fall off during use or reprocessing.

2.1.3 According to the dye's own color fastness series select dye

Each dye's introduction has a description of the color fastness of the dye. When selecting a dye, the dye must be selected according to the color fastness grade required by the product, and the color fastness of the color-matching dye should be similar. For example, the color fastness of the dye itself can only reach 2 to 3 grades or even 1 to 2 grades. No matter how good the auxiliary and dyeing process can not dye the products with 4 to 5 grades of color fastness. Because the color fastness of dyes mainly depends on the binding force between dyes and fibers, if the bond between the two is not strong, how much external force can not make them a solid combination, even if the color has improved , but also can not withstand washing, friction and other external factors.

2.1.4 dye uptake rate of fibers

Different dyes exhibit different rates of dye uptake, and under different dyeing conditions, the dye uptake rate of the same dye is also different. Therefore, when choosing dyes, the dyeing rate must be considered. Otherwise, the dyeing phenomenon will occur between the dyes. That is, one of the dyes will occupy the dyeing position of the fiber in advance, causing other dyes to be dyed only on the surface of the fiber. It forms a strong bond with the fiber and is first destroyed in subsequent processes or in daily use. This is why some colors appear to have a color that is completely different from the original color. Therefore, when selecting a dye, it is necessary to use dyes with similar dyeing rates under the same conditions, which is very helpful for the next step in the formulation process.

2.1.5 Good compatibility between dyes

Different dyes of the same type of dyes have different compatibility, and the greater the compatibility, the better the ability of the dyes to fight each other. Matching dyes must have good compatibility. It is best to use three primary colors for colors that are not easy to fight. The three primary colors are the best in the compatibility of each type of dye, and they are also the most complete and most positive dyes that can be spelled out. Therefore, some of the more difficult to dye the best color to use three primary colors to match, try not to use other dye hard fight, prone to race dyeing phenomenon, easy to dye flowers.

2.1.6 Minimize the number of dyes required

To choose a dye, first select the dye that is similar in shade to the desired color, and then use one or two dyes to supplement the color shade that is missing in the main dye, and select the dye that belongs to the same color to dye the color Pure, clean, bright, full. Try not to use four or five dyes to fight color. It is not good to color, and it is not easy to operate a large number of dyes. Moreover, although the color is matched, the colored light that is dyed is not bright and full, and the dye cannot be sufficiently combined with the fiber, resulting in poor color fastness.

2.2 Selection and use of additives

2.2.1 Selecting the Right Additive

After determining the type of dye, the choice of additives is also very important. Generally, as much as possible, the auxiliary agent that matches the dye is selected. If it is an ordinary dye that is conventionally used, it is necessary to focus on the determination and use of the auxiliary agent. For dark colors, the dye is not easily exhausted. Additives can be added in batches to increase the exhaustion rate. It can also improve the firmness of dye adsorption and play a role in fixation.

2.2.2 Minimize the amount of retarder

The slow-dyeing retarder should reduce the amount as much as possible, otherwise it has a stripping effect. On the one hand, it will reduce the dyeing rate, on the other hand, it will weaken the binding of dyes and fibers, and will deteriorate the color fastness. The dyeing effect can be achieved by adjusting the dye and heating rate for the color that is easy to dye.

2.2.3 Selection of fixing agent

The use of fixing agents will greatly improve the dye fastness, generally at least 0.5 to 1 grade, but the choice of fixing agent should also consider the fastness of the dye. Instead of looking at individual items. For example, after the reactive dyes are treated with a cationic low-molecular-weight or polyamine-type fixing agent, the washing fastness of the fabric is 4 to 5, but the light fastness will decrease. When fixing, it is necessary to strictly control the amount of fixing agent, fixing temperature, and fixing time.

2.2.4 soaping and washing

When soaping and washing, be sure to wash fully, ensure the temperature and time of washing, otherwise, the floating color of the fabric surface will fade during use.

2.2.5 Use of softener

In order to obtain a full and soft feel, softeners should be added. Softeners are cationic, anionic, non-ionic and silicone. The softener is the last step after the dyeing process. The dyes and softeners react further, which may reduce the color fastness. In particular, after the acid dyes are dyed, the silicone softener is used. Even when the softening treatment is performed, some dyes may even be removed. , make the color lighter. Therefore, the amount of softener used for softening should be just right. Otherwise, it is not only sticky but also affects the color.

3, the formulation of dyeing process

Dyeing process is the key link in dyeing. When making the process, we must determine the dyeing time, heating rate and holding time according to dyes and products. For light colors, the heating rate is slower and the holding time can be shorter. For darker colors, the heating rate can be faster, but the holding time must be sufficient, so that the dye and fiber can be fully combined and play a fixation role.

4 Conclusion

In short, there are many factors that affect the fastness of textile dyeing. For internal factors, it means that each process of production is done to ensure that the product can have excellent color fastness indicators, meet daily consumption and reprocessing requirements; for external factors In terms of products, we must pay attention to the factors that can reduce the color fastness, such as washing temperature, detergent and washing method, and the degree of friction and exposure time. Make the product use better.