Why do sponge products turn yellow? UV absorber manufacturer

Generally, from the perspective of additives, the yellowing of the sponge includes the following four types: 1. During the foaming/processing of the sponge, the yellowing caused by thermal oxygen aging due to high temperature. 2. Yellowing caused by gas fumigation caused by exposure to nitrogen oxides (NOx) in the air. 3. Fabric pollution caused by sponge. 4. The yellowing of the sponge caused by exposure to ultraviolet rays. Types of sponge materials: 1. Chemical sponge Polyurethane soft foam rubber. Polyurethane is the most common polymer material in life and is widely used in the production of various “sponge” products. And elastic materials for shock absorption and anti-friction purposes, such as shoe soles, tractor tank track substrates. 2. Industrial sponges There are many types of sponges used in industrial production, including foamed cotton, shaped cotton, rubber cotton, memory foam, etc. Extended information: Polyurethane is the most common polymer material in life, and it is widely used in the production of various “sponge” products. And elastic materials for shock absorption and anti-friction purposes, such as shoe soles, tractor tank track substrates. According to whether the product has yellowing phenomenon under light, polyurethane adhesives are divided into general-purpose isocyanate polyurethane adhesives and yellowing-resistant isocyanate polyurethane adhesives. General-purpose isocyanate, that is, aromatic isocyanate is currently the most widely used isocyanate in the polyurethane industry. Because the methylene group connected to the benzene ring in the structure is easily oxidized to form a quinone chromophoric group, the yellowing of the material occurs.