The color fastness to rubbing is an important item of textile color fastness testing and the most common test item in the trade process. It refers to the degree of discoloration of dyed fabrics after rubbing. The focus is on evaluating the resistance of dyes to mechanical friction. There are two kinds of dry friction and wet friction.
The principle is to fix the textile sample on the friction tester platform, and rub it with a dry friction cloth and a wet friction cloth respectively, and then use the staining degree of the white cloth as the evaluation basis. The fabric with poor friction fastness will seriously affect its use.
1. Effect of fabric surface morphology
Since unfixed dyes are the main cause of poor color fastness to rubbing, under dry conditions, dry rubbing is very easy for rough surface, abrasive or raised fabrics, as hard as hemp fabrics, denim fabrics and paint printed fabrics. The dye, paint or other colored substances accumulated on the surface of the fabric are ground down, and even some colored fibers are broken and colored particles are formed, which further reduces the color fastness to dry rubbing. For abrasive or raised fabrics, the fleece on the surface of the fabric and the surface of the friction cloth form a certain angle, which is not parallel, so that the friction resistance of the friction head during reciprocating motion increases, making the fabric resistant to dryness The color fastness to rubbing decreases.
2. The influence of the chemical structure of reactive dyes
Cellulose fiber fabrics dyed with reactive dyes have two main factors that cause color transfer during the wet rub color fastness test:
One is that the water-soluble dye is transferred to the friction fabric when rubbing, so that the original color is faded and the friction cloth is stained;
The second is that the partially dyed fibers break during friction, forming tiny colored fiber particles and transferred to the friction fabric, causing staining.
3. Effect of dyeing degree
The research also proves that the color fastness to wet rubbing of dyed fabrics with reactive dyes is closely related to the depth of dyeing, that is, when wet rubbing, the amount of color transfer and the depth of dyeing are almost in a good linear relationship. Saturation is the most important factor. When dyeing dark colors, the concentration of the dye used is high, but it cannot exceed the saturation value greatly, because excess dye cannot be combined with the fiber, but can only accumulate on the surface of the fabric to form a floating color, which seriously affects Color fastness to wet rubbing of fabrics.
In addition, unspecified cotton fibers will swell under wet conditions, friction will increase, and fiber strength will decrease. These have created good conditions for the breakage, shedding and color transfer of colored fibers. Therefore, proper pretreatment of cellulose fibers before dyeing, such as mercerizing, singeing, cellulase finishing, scouring, bleaching, washing, drying, can improve the surface finish and wool effect of the fabric and reduce friction resistance , Reduce floating color, thereby effectively improving the color fastness to wet rubbing of the fabric.
