Do You Know What Is The Color Fastness To Rubbing?

Color fastness is one of the most important quality indicators of textiles. It is also one of the most common inspection items in the trade of textiles.

The so-called color fastness refers to the degree of color retention of dyed textiles under physical and chemical effects, namely the ability of textiles to resist color and friction, which can be divided into dry friction and wet friction.

* the effect of colour fastness to rubbing.

Sound factors *

01

The influence of fabric surface morphology -

Because the unfixed dye is the main cause of poor color fastness to rubbing, under dry conditions, for rough or grind, fuzzing fabrics, hard linen fabrics, denim fabrics and pigment printing fabrics, if dry friction is easy to wear dye, paint or other colored substances accumulated on the surface of the fabric, even some of the colored fibers will break and form colored particles, which will further reduce the dry rubbing fastness.

For grind or fuzzing fabrics, the surface of the fabric has a certain angle between the surface of the fabric and the surface of the rubbing cloth, which is not parallel, so that the frictional resistance of the friction head is increased during the reciprocating motion, and the color fastness to dry friction of the fabric decreases.

02

The influence of fabric structure -

The surface of light weight fabric (usually synthetic fiber or silk fabric) is loose because of the relatively loose fabric structure. When dry friction is applied, the sample will slide partially with the movement of the friction head under the action of pressure and friction, thus increasing the frictional resistance and increasing the friction efficiency.

But in wet friction, the situation is completely different from the cellulose fiber.

Because the hygroscopicity of the fibers is very low or the water swelling effect is not obvious, and the presence of water plays the role of lubricants, the moisture fastness to rubbing of such fabrics is obviously better than that of dry rubbing fastness.

Therefore, for certain fabrics, the color fastness to wet rubbing is better than that of dry rubbing fastness.

At the same time, the choice of dyes, dyes, dyeing and finishing conditions will also affect the color fastness to rubbing, but it is not very important compared with physical factors such as fabric structure and surface morphology.

Most of these cases are dark products, such as black, red and Tibetan blue.

Of course, for corduroy, twill and pigment printing fabrics, wet fastness is usually 2 or even lower under wet condition because of its dyestuff and dyeing process. It is not superior to its dry rubbing fastness.

03

- the influence of reactive dyes on the chemical structure -

There are two main factors that cause color pfer in cellulose fabric dyeing with reactive dyes.

(1) water soluble dyes are pferred to the friction fabric when rubbing, so that the original sample is fading and the friction cloth is stained.

(2) two is that some of the dyed fibers break when they are rubbing, forming tiny colored fibers and pferring them to the friction fabric, resulting in staining.

The factors that may affect the color fastness to wet rubbing of reactive dyes are:

(1) the structure and characteristics of reactive dyes themselves;

(2) the nature of the fabric;

(3) pretreatment effect, cloth surface damage and surface finish.

(4) dyeing process and effect of soaping after dyeing;

(5) fixing effect after dyeing;

(6) the influence of dyed fabric finishing.

The results show that although the covalent bond strength, bond stability and adhesion of the reactive dyes with different chemical structures are different from those of cellulosic fibers, they have no significant difference in the color fastness to wet rubbing of dyed fabrics.

When wet dyed fabric is dyed, the covalent bond formed between dye and fiber will not break and generate floating color.

The dyes that are pferred are usually supersaturated, which do not form covalent bonds with the fibers, and the dye that is adsorbed by fan Edward force is the so-called floating color.

04

- the influence of reactive dyes on dyeing degree -

The color fastness to wet rubbing of reactive dyed fabrics is closely related to the depth of dyeing.

Excessive dyes can not be combined with fibers, but can only accumulate on the surface of fabric to form floating color, which seriously affects the wet rubbing fastness of fabrics.

The cotton fibers without special treatment will be swelling under the wet condition, the friction force will increase, and the strength of the fibers will decrease. All these create favorable conditions for the breakage, falling off and color pfer of colored fibers.

Therefore, proper pretreatment of cellulose fibers before dyeing, such as mercerizing, singeing, cellulase polishing, scouring, bleaching, washing and drying, can improve the surface finish and wool efficiency, reduce friction resistance and reduce floating color, thus effectively improving the wet rubbing fastness of fabrics.

05

- the influence of Softeners -

The color fastness of reactive dyestuffs was improved by softening finishing.

Softeners are lubricated, which can reduce the friction coefficient and prevent the dye from falling off.

Cationic softeners can also form anions with anionic dyes, and dyes are not easy to fall off.

At the same time, the color of the dye reduces the solubility of the dye and improves the wet rubbing fastness.

However, softeners with hydrophilic groups are not conducive to the improvement of wet rubbing fastness.

In the process of production practice, the water soluble groups of dyes can be blocked by fixing agents, controlling the pH value of the finished fabric, removing the floating color and improving the smoothness of the fabric, thereby improving the wet rubbing fastness of the fabric.

Proper pre drying can avoid dye "swimming".

The factors that need attention include the dosage of caustic agent, steaming time, washing method and adequate soaping. The former two are closely related to the degree of hydrolysis of dyes, and the latter two are directly related to the floating color of dyes.

The dyed fabric, especially the long run pad dyeing, should be washed and soaped thoroughly to remove the floating color and unreactive and hydrolyzed dyes on the surface of the fiber, so as to avoid affecting the color fastness. If no attention is paid to the post-treatment of dyeing, it will cause very poor color fastness and at the same time the chromatic light will also become dark.

In the above factors affecting the color fastness of rubbing, the principle of each factor is quite different and the degree of influence varies.

The problem of color fastness seems simple, but the factors involved are quite complex.