Why do sponge products turn yellow?
Usually, from the analysis of additives, the yellowing of sponges include the following four kinds.
1, sponge foam / processing process, due to high temperature caused by thermal oxygen aging yellowing.
2, exposure to nitrogen oxides in the air (NOx) caused by the gas fumigation yellowing.
3, sponge caused by fabric pollution.
4, sponge exposure to ultraviolet light and caused by yellowing.
Sponge material types.
1, chemical sponge polyurethane soft foam rubber, polyurethane is the most common life of a polymer material, widely used in the production of a variety of “sponge” products. As well as shock absorption, anti-friction use of elastic materials, such as shoe soles, tractor tank track liner.
2, industrial sponge industrial production using a variety of sponges, there are foam, styling cotton, rubber cotton, memory foam, etc.
Extended information: Polyurethane is the most common polymer material in life, widely used in the production of a variety of “sponge” products.
It is also used as an elastic material for shock absorption and anti-friction purposes, such as shoe soles and tractor tank track linings.
Polyurethane adhesives are divided into general-purpose isocyanate polyurethane adhesives and yellowing-resistant isocyanate polyurethane adhesives according to whether or not the product will yellow under light.
General-purpose isocyanate, i.e. aromatic isocyanate, is the most widely used isocyanate in the polyurethane industry, and is susceptible to yellowing due to oxidation of the methylene group linked to the benzene ring in the structure to produce quinone-like color-emitting groups.
