The self-expanding polyurethane foam is a chemical product sold in ready-to-use spray cans, usually in 750 ml format, which is extruded manually when the can is ready for manual dispensing, or through special guns for polyurethane foam.
The polyurethane foam is generated following a cross-linking process of the polymers that compose it, considerably increasing its initial volume, it solidifies in a few hours by reaction with humidity, generating a breathable and filtering material capable of sealing and creating an effective thermo-acoustic barrier.
- The mixture contained within the can, called pre-polymer, is composed of isocyanate, polyol and propellant.
- The self-expanding and sealing effect is given by the propellant contained in the mixture which, at the time of extrusion, presents itself in a liquid and sticky state allowing adhesion to the material.
By reaction with the humidity of the air the propellant passes to the gaseous state creating gas bubbles, called cells, which increase the volume of the mixture generally by about 20% / 30% and, in some cases, almost twice as much as in the initial volume.
Taking this feature into account, it is important to remember not to completely fill the cavity, joint or hole with foam to prevent its volume increase from causing the mixture to escape from the affected area. For the SprayFoam Insulation this is important now.
The polyurethane foam is:
- mobile (you can take it with you everywhere)
- quick and easy use (without large preparations)
- advantageous relationship between storage / transport volume and the yield of a can
The hardened foam is:
- resistant to aging, to rot
- high resistance to many chemicals (eg oils, greases, solvents, fuels)
- high adhesion to the most common construction materials
- it can be cut and painted
- temperature resistant from – 40 to +100 ° C
- high soundproofing power (approx. 59 dB)
- high coefficient of thermal conductivity [ca. 0.39 W / (m · K)]
- adheres to almost all construction materials: eg cement, plaster, marble, stone, hard PVC, plastics, metal and wood
- the hardened foam is free of isocyanate and therefore not dangerous to health
- does not contain formaldehyde
- it is not resistant to ultraviolet rays
- does not adhere to silicone, oils and greases, polyethylene, teflon or the like
A 25 mm thick layer of polyurethane foam has the same insulating characteristics as:
- 40 mm of polystyrene
- 45 mm of mineral wool
- 50 mm of cork
- 65 mm of masonite
- 140 mm of wood
- 350 mm of limestone
- 860 mm of bricks
When To Use Polyurethane Foam
Thanks to the great qualities of thermo-acoustic insulation and to the breathable and filtering properties, the self-expanding polyurethane foam is widely used in various sectors, both professional and do-it-yourself, mainly in the construction field, including:
Installation of windows and doors such as doors and windows as thermal and acoustic insulation and sealing of external air leaks (in door and window frames, in attics and lofts, near power outlets, in conjunction with pipes, skirting boards or flooring), but be careful, read our article “Polyurethane foam: when not to use it when laying the window” to learn more about this aspect.