What factors affect the color fastness of textile friction?

The dyeing of textiles is a production project that the textile industry must pay attention to. The beautiful garments are all dyed before they can be displayed. Textile dyeing will inevitably have the occurrence of discoloration and fading, so what factors are affected by dying and fading?
The factors affecting the rubbing fastness of dyed fabrics are the important ones of the color fastness test of textiles. It is also the most common test item in the trade process. It refers to the degree of color loss after dyeing fabrics. The resistance to mechanical friction is divided into dry friction and wet friction.
The principle is to fix the textile sample on the friction tester platform, and respectively rub it with dry friction cloth and wet friction cloth. Finally, the degree of white cloth staining is used as the evaluation basis, and the fabric with poor rubbing fastness will seriously affect its use.
1. The influence of the surface morphology of the fabric is due to the fact that the unfixed dye is the main cause of poor color fastness to rubbing. Under dry conditions, for rough or fluffed, raised fabrics, hard as hemp fabric, denim fabric and paint printed fabric If dry friction is used, it is easy to grind down the dye, paint or other colored materials accumulated on the surface of the fabric, and even cause some of the colored fibers to break and form colored particles, so that the dry rubbing fastness is further lowered. For a ground or raised fabric, the surface of the fabric has a certain angle with the surface of the rubbing cloth, which is not parallel, so that the frictional resistance of the rubbing head during reciprocating motion is increased, so that the fabric is resistant to dryness. The color fastness to rubbing is reduced.
2. Influence of chemical structure of reactive dyes Cellulose fiber fabric dyed with reactive dyes has two main factors causing color transfer when performing wet rubbing fastness test: First, water-soluble dyes are transferred to friction during friction. On the fabric, the original color is faded and the rubbing cloth is stained; the second is that the partially dyed fiber breaks when rubbed, forming tiny colored fiber particles and being transferred to the rubbing fabric to cause staining.
The factors affecting the fastness to wet rubbing of reactive dyes are: the structure and characteristics of the reactive dye itself; the properties of the fabric; the pretreatment effect, the damage of the fabric surface and the surface finish; the dyeing process and the effect of soaping after dying; Fixing effect; effect of dyeing fabric finishing.
Studies have shown that although there are some differences in covalent bond strength, bond stability and adhesion between reactive dyes of different chemical structures and cellulose fibers, there is no significant difference in the wet rubbing fastness of dyed fabrics.
When the dyed fabric is wet rubbed, the covalent bond formed between the dye and the fiber does not break to produce a floating color. The dye that is transferred is usually a supersaturated dye that does not form a covalent bond with the fiber and which is adsorbed by van der Waals force, so-called floating color.
3. The influence of dyeing degree also proves that the color fastness to wet rubbing of reactive dyed fabrics is closely related to the depth of dying, that is, when wet rubbing is performed, the amount of color transfer and the dyeing depth are almost in a good linear relationship. The supersaturation of the dye is the most important factor when dying. When dyeing dark color, the concentration of the dye used is higher, but it cannot greatly exceed the saturation value, because the excess dye cannot be combined with the fiber, but only on the surface of the fabric. The formation of floating color seriously affects the wet rubbing fastness of the fabric.
In addition, cotton fibers that have not been specially treated will swell under wet conditions, friction increases, and fiber strength decreases, which creates favorable conditions for the breakage, shedding, and color transfer of colored fibers. Therefore, proper pretreatment of cellulose fibers before dying, such as mercerizing, singeing, cellulase finishing, scouring, bleaching, washing, drying, can improve the surface finish and hair effect of the fabric, and reduce frictional resistance. Reduce the floating color, thus effectively improving the wet rubbing fastness of the fabric.
4. Influence of fabric structure Regarding the influence of the fabric structure and the surface morphology of the fabric on the color fastness to rubbing, people did not pay much attention. The surface of the sample of light and thin fabrics (usually synthetic or silk fabrics), due to the relatively loose fabric structure, the sample will undergo the friction and friction under the action of friction and friction. Partial slippage increases the frictional resistance and increases the friction efficiency.
However, when wet friction is applied, the situation is completely different from that of cellulose fibers. Because the fiber has very low hygroscopicity or the water puffing effect is not obvious, and the presence of water acts as a lubricant, which makes the wet rubbing fastness of such fabrics significantly better than the dry rubbing fastness, which is related to people. It is generally believed that the dry rubbing colorfastness of textile products should be significantly better than the concept of wet rubbing fastness, and often cause people’s doubts. Therefore, it is not uncommon for certain specific fabrics to have better-wet rubbing fastness than dry rubbing fastness. At this time, the dye type selected, the performance of the dye, the dyeing and finishing process conditions, etc., although it also affects the color fastness to rubbing, compared with the physical factors such as the texture and surface morphology of the fabric, It seems not very important.
Statistics show that most of these situations are still dark products such as black, red and navy. Of course, for fabrics such as corduroy, twill, and paint printing, in wet conditions, the color fastness to wet rubbing is usually 2 or even lower due to the dye and printing process used by itself. Not better than its dry rubbing fastness.
5. The effect of softener by soft finishing to improve the colorfastness of reactive dye printing. The softener has a lubricating effect that reduces the coefficient of friction and prevents the dye from falling off. The cationic softener can also form a lake with an anionic dye, and the dye is not easily peeled off. At the same time, the lake reduces the solubility of the dye and improves the wet rubbing fastness.
However, a softening agent having a hydrophilic group is disadvantageous for the improvement of wet rubbing fastness. In the production practice process, the water-soluble group of the dye can be blocked by using a fixing agent, the pH value of the finished color cloth can be controlled, the floating color can be removed, and the smoothness of the fabric can be improved, thereby improving the wet rubbing fastness of the fabric. Proper front-stage pre-baking can avoid dye “swim”. The factors that need attention are the amount of alkali agent, steaming time, water washing method, and adequate soaping. The former two are closely related to the degree of hydrolysis of the dye, and the latter two are directly related to the floating color of the dye.
The dyed fabric, especially the long-wheel rolling, should be thoroughly washed, soaped, etc., to remove the floating surface of the fiber surface and the unreacted and hydrolyzed dye, so as not to affect the color fastness, such as not paying attention to the post-treatment of dying, It will cause poor color fastness and the shade will become dull.
Summarizing the above factors affecting the colorfastness of fabric rubbing, the principle of action of each factor varies greatly, and the degree of influence varies. The color fastness problem seems simple, but the factors involved are quite complicated. Over the years, no matter in the field of dye research and production, or in the field of textile dyeing and finishing, people have invested a lot of manpower and material resources to solve the problem of colorfastness of textile products, and have made great progress and various new ones. Dyes, new processes, and new auxiliaries continue to emerge, but there are still many problems that need to be addressed.