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Advantages and disadvantages of polyurethane rigid foam in external wall insulation system
Time:2020/8/25 15:06:40    

Waterproof performance

Polyurethane rigid foam is a kind of microporous foam with a closed cell ratio greater than 92% which has high water vapor permeability resistance and good water impermeability. The rigid polyurethane foam layer formed by on-site pouring or spraying is tightly bonded to the base layer, so the rigid polyurethane foam layer and the base layer form a whole which is not easy to delaminate or peel off, avoiding the penetration of water along the interlayer. In addition, the raw material of the rigid polyurethane foam is liquid and the slurry has certain fluidity which can enter the pores of the base layer to foam, block the gaps and play a role in sealing.

Excellent thermal insulation performance

The thermal conductivity of rigid polyurethane foam is very low, its newly made foam products at room temperature is generally about 0.0174W/(m·K). After the epidermis is cut and exposed to the air for a long time, the thermal conductivity increases year by year and maintain stable at around 0.021W /(M·K).

Corrosion and aging resistance

    Polyurethane rigid foam has good chemical stability to general solvents such as gasoline and benzene and dilute concentrations of acids, alkalis, and salts. However, like other polymer materials, aging will occur under direct sunlight which will reduce the mechanical and physical properties of the material, but the rate of change is very slow. Research shows that the thermal conductivity of rigid polyurethane foam at 20°C can be kept stable for 50 years. For external wall insulation systems, if the polyurethane rigid foam layer has a protective and decorative system outside, its performance will remain better.

Good crack resistance

  Rigid polyurethane foam has a certain degree of extensibility and resistance to external deformation. Under the action of external force, temperature change, dry and wet changes, it is not easy to crack which effectively ensures the stability and waterproofness of the system.Even if the main structure undergoes normal deformation such as shrinkage, expansion, small cracks, etc., the rigid polyurethane foam will not crack or peel, thereby avoiding the cracking of the protective decoration system caused by the EPS shrinkage in the EPS system.

Wide range of applications

  Polyurethane rigid foam is suitable for various thermal insulation projects in industrial and civil buildings and can be used for new construction or repair of old buildings.

High mechanical strength, strong stability

  The rigid polyurethane foam used for building insulation has a density of 32-50kg/m3 and high mechanical strength. Compared with EPS and rock wool, rigid polyurethane foam has stronger resistance to external forces and can withstand collisions between human bodies and normal handling items.

Good adhesion

Polyurethane rigid foam is firmly bonded with various building materials such as steel, concrete, plastic steel, and masonry. Even under severe temperature and humidity, it bears the combined load of wind, dead weight and normal collision, etc., and the insulation layer has not separated from the base. Research by the American SPF Association shows that rigid polyurethane foam can resist the influence of strong winds as long as it is correctly constructed. UL laboratory confirmed that the use of polyurethane rigid foam laminated roof and metal roof greatly improve the wind resistance of the roof.

Insufficiency of polyurethane rigid foam insulation

1. The construction machinery is complex and requires professional and technical personnel;

2. There are liquid droplets floating in the air at the construction site, especially when spraying, good ventilation and certain labor protection are required;

3. The surface of the sprayed rigid polyurethane foam is uneven. If the exterior decoration is a flat coating, you need to trim the polyurethane foam.

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