What are the reasons for the yellowing of textiles?

1. Light yellowing:

Photoyellowing refers to the yellowing of the surface of textiles and clothing due to the oxidative cracking reaction of molecules caused by the irradiation of sunlight or ultraviolet light. Photoyellowing is most common in light colored garments, bleach treated fabrics, and whitened treated fabrics. After the fabric is illuminated, the light energy is transmitted to the fabric dye, causing the dye conjugate to crack, causing light fading, and the surface of the fabric appears yellow. Among them, visible light and ultraviolet light are the main factors causing the fading of fabrics colored by azo dyes and phthalocyanine dyes respectively.

2. Phenol yellowing:

Phenolic yellowing is generally the yellowing of the fabric surface caused by the contact transfer of NOX and phenolic compounds. The main reaction substance is usually the antioxidant contained in the packaging material, such as butylphenol (BHT). Clothing and footwear are packaged and transported for a long time after leaving the factory, and the BHT in the packaging material will react with NOX in the air, which will cause the clothing to turn yellow.

3. Oxidative yellowing:

Oxidative yellowing refers to the yellowing of fabrics after being oxidized by the atmosphere or other substances. Vat dyes or auxiliaries are usually used in the dyeing and finishing of textiles and clothing. After contacting with oxidizing gases, oxidation and reduction will occur to cause yellowing.

4. Yellowing of whitening agent:

Whitening agent yellowing mainly occurs on light-colored fabrics. When the residual whitening agent on the surface of clothing migrates due to long-term storage, resulting in excessive local whitening agent, resulting in clothing yellowing.

5. Yellowing of finishing agents such as softeners:

When the softening additives used in the finishing process of clothing are subjected to conditions such as heat and light, the cations in them will be oxidized, resulting in yellowing of the softened parts of the fabric.