Polyurethane rigid foam is a high molecular polymerization made of isocyanate and polyether as the main raw materials, mixed by special equipment, and foamed on-site by high-pressure spraying under the action of various additives such as foaming agent, catalyst, and flame retardant. There are two types of polyurethane foam, soft foam and hard foam. Soft foam has an open-cell structure, and hard foam has a closed-cell structure; soft foam is divided into two types: crusted and non-skinned.