Color fastness refers to the degree to which the color of textiles fades under various external factors such as light, washing, ironing, sweat stains, friction, and chemical agents during processing or use. It is an important indicator in textile testing.
Products with poor color fastness may contaminate other clothing during wearing, or come into contact with other clothing during washing, affecting their hygiene and wearing performance. In severe cases, it can cause harmful substances such as dye molecules and heavy metal ions to be absorbed by the human body through the skin, posing a threat to skin health.
What is color fastness to light?
It refers to the ability of dyed fabrics to maintain their original color under sunlight.
Why does light affect the color of textiles?
Under the irradiation of light, dye molecules absorb light energy, the energy level increases, and the molecules are in an excited state. The chromophore system of dye molecules changes or is destroyed, leading to the dispersion of dyes and the occurrence of discoloration or fading.
If the color fastness to light is not up to standard during testing, how should different fabrics be targeted for improvement? What are the factors that affect color fastness to light?
cotton fabric
All cotton knitted fabric
The project can be improved by treating the fabric with ultraviolet absorbers or using reactive dyes with strong light resistance.
All cotton woven fabric
All cotton woven fabrics can be improved by using ultraviolet absorbers to treat the fabric, using reactive dyes with strong light resistance, or using vat dyes to improve the project.
The trend of light resistance of reactive dyes is:
The larger the molecular weight of a dye, the stronger its resistance to light;
Fluorine containing reactive dyes have better light resistance than conventional reactive dyes.
Note: The light resistance of vat dyes is significantly better than that of reactive dyes, but currently only the vat dye dyeing process for continuous dyeing of woven fabrics is relatively mature, so this method is only applicable to plain woven fabrics.
All polyester fabric
Polyester fabrics can be improved by using ultraviolet absorbers to treat the fabric or using disperse dyes with strong light resistance.
The trend of light resistance of disperse dyes is:
The larger the molecular weight of a dye, the stronger its resistance to light;
The light resistance of disperse dyes with anthraquinone structure is stronger than that of disperse dyes with conventional azo structure.
Multi component fabric
For multi-component fabrics, it is first necessary to determine which component has poor light resistance and which dye is used on it based on its specific composition. Then, targeted solutions should be selected based on the characteristics of this dye, and specific case studies should be analyzed.
The ranking of light resistance of conventional dyes in various categories is:
Vat dyes (cellulose fibers)>Disperse dyes (polyester fibers)>Cationic dyes (acrylic fibers)>Reactive dyes (cellulose fibers, protein fibers)>Acid dyes (nylon, protein fibers)
Adhesive printing products
The color fastness to light of adhesive printing products is a direct reflection of the relevant properties of the coating products used. Usually, the larger the molecular weight of the coating, the stronger its light resistance. The project can be improved by replacing with coatings with strong light resistance!
