Polyurethane was discovered in 1937. It is a common name for material which can be hidden under many forms, such as, rigid foam, flexible foam, coatings, sealants, adhesives and elastomers. The main constituents are isocyanate and polyol. Depending on the components and proportions it can have different properties. Polyurethane is widely used in industry and has a variety of uses in everyday life. Rigid foam is used in building construction as a thermal insulation. It is produced by the so-called polyurethane system. This material is light and durable. Besides, it has closed-cell structure and a low thermal conductivity.