The injected polyurethane sandwich panel, in English structural insulated panel, or structural insulating panel, SIP), is an industrial product designed to make enclosures in construction, industrial and residential, and in the insulation industry. It is mainly used as thermal and acoustic insulation, as waterproofing and as an enclosure. It is worth noting that it is a resistant and light product, which allows it to be used with a minimum of physical effort on the part of the operator carrying out the assembly.

Construction with polyurethane sandwich panels dates back to the end of World War II, when there was a great demand for conservation and refrigeration chambers. At that time it was considered that this construction method would only be useful for functional and industrial buildings. But in recent years, injected polyurethane sandwich panels have been used for the construction of a wide variety of buildings, satisfying the demands of architects.

The sandwich panel is formed by an insulating core of rigid polyurethane foam joined to two metallic and non-metallic outer covering layers, the metallic ones generally made of steel or aluminum. During the manufacturing process, the cover layers are prepared by profiling and punching if necessary according to the desired initial shape, they are transported to the press and there the mixing head injects the components with a predetermined dosage, forming polyurethane foam in the liquid phase; Its chemical reaction produces foam growth, adhering to the two layers of coverage, lower and upper. With the development of heat and pressure there is a time under pressure, which will be shorter or longer depending on the thickness, until curing (dimensional stability). The manufactured sandwich panels will be cut or not according to need to the predetermined lengths, and are stacked and packaged for transport to the site.

Sandwich panels, thanks to their physical, mechanical and design properties, are available for a wide variety of applications: facades, roofs, false ceilings, interior partitions and cold rooms.