1. Light yellowing
Light yellowing refers to the yellowing of the clothing surface due to the oxidative cracking reaction of molecules caused by the irradiation of sunlight or ultraviolet light on textile fabrics. 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. Phenolic 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). After a long period of packaging and transportation after leaving the factory, the BHT in the packaging material will react with NOX in the air, causing yellowing.
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 dyeing and finishing. After contacting with oxidizing gases, oxidation and reduction will occur to cause yellowing.
4. Yellowing of whitening agent
Brightener yellowing mainly occurs on light-colored fabrics, when the residual brightener on the surface migrates due to long-term storage, resulting in excessive local brightener, resulting in yellowing of clothing.
5. Yellowing of softener
When the softening additives used in the finishing process 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.