Why do sponge products turn yellow?
Generally, from the perspective of additives, the yellowing of sponge includes the following four types:
1. During sponge foaming/processing, thermal oxygen aging and yellowing caused by high temperature.
2. Yellowing caused by exposure to nitrogen oxides (NOx) in the air.
3. Fabric contamination caused by sponges.
4. Yellowing of sponge caused by ultraviolet radiation.
Type of sponge material:
1. Chemical sponge polyurethane soft foaming rubber, polyurethane is the most common polymer material in life, which is widely used to make various “sponge” products. And elastic materials for shock absorption and friction resistance, such as shoe soles, tractor and tank track soles.
2. There are many kinds of sponge used in industrial sponge production, including foam cotton, shaped cotton, rubber cotton, memory cotton, etc.
Extended information: Polyurethane is the most common polymer material in life, which is widely used to make various “sponge” products.
And elastic materials for shock absorption and friction resistance, such as shoe soles, tractor and tank track soles. According to whether the product yellows under light, polyurethane adhesives are divided into general isocyanate polyurethane adhesives and yellowing resistant isocyanate polyurethane adhesives.
General purpose isocyanates, namely aromatic isocyanates, are the most widely used isocyanates in the polyurethane industry at present. Because the methylene linked to the benzene ring in the structure is easy to be oxidized to form quinone chromophore, the material will turn yellow.
