How is color fastness rated?

Staining is not up to standard

The floating color on the cloth is related to the transfer of some colored fiber particles;

It is related to the selected dye species, dyeing process and post-processing process;

Acetate and nylon have good coloring rates for a variety of dyes at lower temperatures;

Thermal migration phenomenon when dyeing with disperse dyes;

Water has a plasticizing effect on spandex. Under wet conditions, the dye that enters the amorphous area of ​​spandex can easily migrate to the fiber surface. Under the action of external force, the transfer of dye can easily occur, staining the lining cloth;

In fact, in elastic fabrics containing spandex, the proportion of spandex filaments is quite low and is usually not exposed on the surface of the fabric. The color fastness problem of spandex will not seriously affect the color fastness of the entire fabric. The color fastness problem of spandex-containing elastic fabrics is mainly due to the color fastness problems of cotton, polyester, nylon and other fibers on the surface of the fabric itself;’

Improve fabric dyeing properties, such as dye penetration, sufficient color fixation, strengthen soaping, washing, reduction cleaning, and fully remove floating colors;

Use color-fixing agents to improve the fabric’s water resistance and color fastness to washing;

Use corresponding additives to prevent sweat from destroying the dye carrier structure

Fabric organizational structure;

Molecular structure of dye²;

The bonding state of fiber and dye changes with dye concentration;

Color matching using dyes with different light fastnesses;

Dyes with good diffusion properties and uniform penetration within the fiber have high color fastness to sunlight;

Some additives applied to fabrics will affect the color fastness to sunlight;

Choose the dye correctly

Formulate and implement reasonable dyeing process conditions to make the fabric dyed evenly and thoroughly and fully fixed; strengthen the avoidance of adverse effects of post-finishing

After dyeing, soap and wash to fully remove floating color

Using light fastness enhancer

Use anti-UV finishing agents where appropriate

Active chlorine reacts with dyes, causing oxidative decomposition of dyes;

Peroxide reacts with the dye matrix, causing the dye to change color or fade, or destroy the combination of the dye and the fiber;

The color fastness of dyes to chlorine bleaching and non-chlorine bleaching is related to the dye structure;

Reasonably screen dyes and choose dyes with chlorine bleaching resistance and non-chlorine bleaching structureMaterial;

Fully scouring before dyeing and washing after dyeing, strive to remove impurities and keep the fabric neutral, because the presence of impurities, acid and alkalinity will accelerate the decomposition of dyes under chlorine bleaching and non-chlorine bleaching conditions;

Use chlorine-resistant color fixing agent to improve the chlorine resistance of the dye and strengthen the combination of dye and fiber;

Use active chlorine capture agents to prevent dyes from being affected by active chlorine. The disadvantage is that most of these additives are not durable and are rarely used;

White fabrics sometimes turn yellow during storage. The yellowed parts will disappear and return to their original white color after acid treatment. If alkali solution is added again, the yellow color will return. . The main reason is phenol yellowing.

The antioxidant BHT (2,6-di-tert-butyl-p-cresol) commonly used in packaging materials and nitrogen oxides (NOx) in the air A chemical reaction occurs to generate DTNP (2,6-di-tert-butyl-p-nitrophenol). DTNP is colorless in an acidic state and easily sublimates and transfers at room temperature. When encountering alkaline substances, it immediately turns yellow. .

Use BHT-free packaging materials, such as PE film, wrapping paper and cartons

Add low-volatile acids such as citric acid, oxalic acid or tartaric acid to maintain the acid pH value of the processed cloth at around 4.5 to 6.0

Choose additives that do not contain BHT and are not easily absorbed, such as weak cationic softeners²

Avoid air pollution and reduce NOx concentration in cloth processing and storage places

Fluorescent whitening agent treatment (the acid and alkali resistance of the fluorescent whitening agent must be considered)

Pigment printing: It is a printing method in which insoluble pigments are mechanically fixed on the fabric with the help of adhesive.

Poor color fastness to dry and wet rubbing

The printed surface is whitish

After the washability test, it was found that the printed parts were cracked, peeled off or even broken

Printing adhesives are divided into three categories: hard monomers, soft monomers and functional monomers. Adding more hard monomers will help improve printing The color fastness to rubbing will make the printed area feel hard and prone to cracking, the light resistance will steadily decrease, and it will easily turn yellow.

Adding too much soft monomer can improve the feel and light resistance, but the film strength is too low, which reduces the color fastness to rubbing.

Polyacrylic acid swells easily under wet conditions, which reduces the strength of the film and the color fastness to wet rubbing.

Choose the right adhesive

Use appropriate softener

Pay attention to the baking and color-fixing process