The color fastness of textile dyeing is one of the testing indicators that the textile industry
pays attention to. The dyeing of textiles is related to many conditions. Different conditions can be controlled to dye textiles of different colors. The same thing is to dye a qualified fabric. Control each dyeing process, then we need to understand which factors will affect the color fastness of textiles, and analyze it briefly for you. 1. Reasons affecting the rubbing fastness of dyed fabrics Color fastness to rubbing is an item of textile color fastness inspection, and it is also one of the most common inspection items in the textile trade process. It refers to the fading of dyed fabrics after rubbing. The degree is to assess the resistance of the dye to mechanical friction. It is divided into dry friction and wet friction. The principle is to fix a textile sample of a specified size on the friction tester
platform with a clamping device, and then separately A dry rubbing cloth and a wet rubbing cloth are rubbed. Finally, the degree of staining of the white cloth is used as the evaluation basis. The standard gray sample card is divided into 5 grades. The higher the grade, the better the rubbing fastness and the poorer rubbing fastness. Will seriously affect its use. There are many factors that affect the color fastness to rubbing of fabrics, and several of them are analyzed below. 1. The influence of fabric surface morphology. Unfixed dyes are the main cause of poor color fastness to rubbing. Under dry conditions, the surface is rough or nubuck and raised fabrics are as hard as hemp fabrics, denim fabrics and pigment printing fabrics. If dry rubbing is performed, it is easy to grind off the dyes, coatings or other colored substances accumulated on the surface of the fabric, and even cause some of the colored fibers to break and form colored particles, which further reduces the color fastness to dry rubbing. For sanded or raised fabrics, the fluff on the surface of the fabric and the surface of the friction cloth are at a certain included angle, which is not parallel, so that the friction resistance of the friction head during reciprocating motion increases, and this type of fabric is resistant to drying. The color fastness to rubbing decreased. 2. The study on the influence of the degree of dyeing also proves that the wet rubbing fastness of reactive dyes dyed fabrics is closely related to the depth of dyeing, that is, when wet rubbing, 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 during dyeing. When dyeing dark colors, the dye concentration used is higher, but it cannot greatly exceed the saturation value, because the excess dye cannot be combined with the fiber, but can only accumulate on the surface of the fabric. Floating color is formed, which seriously affects the color fastness to wet rubbing of the fabric. In addition, cotton fibers without special treatment will swell under wet conditions, increase friction, and decrease fiber strength, which creates good conditions for the breakage, shedding and color transfer of colored fibers. Therefore, proper pre-treatment of cellulose fibers before dyeing, such as mercerizing, singeing, cellulase finishing, scouring, bleaching, washing, and drying, can improve the surface finish and hair effect of the fabric, and reduce friction resistance. , Reduce floating color, thereby effectively improving the color fastness to wet rubbing of the fabric. 3. The influence of fabric structure Regarding the influence of fabric structure and fabric surface morphology on the color fastness to rubbing, people have not paid much attention. The surface of the sample of light and thin fabric (usually synthetic fiber or silk fabric), because the fabric structure is relatively loose, during dry friction, the sample will occur with the movement of the friction head under the action of pressure and friction. Part of the slippage increases the frictional resistance and improves the friction efficiency. However, when performing wet friction, the situation is completely different from that of cellulose fibers. Due to the extremely low moisture absorption of the fiber or the insignificant water puffing effect, and the presence of water acts as a lubricant, the color fastness to wet rubbing of this kind of fabric is significantly better than the color fastness to dry rubbing. It is generally believed that the dry rubbing color fastness of textile products should be better than the wet rubbing color fastness, which forms a clear contrast and often causes people's doubts. Therefore, it is not uncommon for certain fabrics to have better color fastness to wet rubbing than dry rubbing. At this time, the selected dye types, dye properties, dyeing and finishing process conditions, etc., will also affect the color fastness to rubbing, but compared with physical factors such as the structure and surface morphology of the fabric, it is It doesn't seem very important anymore. Statistics show that dark products such as black, red and navy blue are the most common occurrences of this kind of situation. Of course, for corduroy, twill and pigment printing fabrics, under wet conditions, due to their own dyes and printing and dyeing processes, their color fastness to wet rubbing is usually level 2, or even lower, and Not better than its color fastness to dry rubbing. 4. The influence of softener Improve the color fastness of reactive dye printing through softening finishing. The softener has a lubricating effect and can reduce the coefficient of friction to prevent the dye from falling off.
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