WHAT IS POLYURETHANE FOAM ?
Polyurethane foam (PF) – is a light firm hydrothermal insulation material with a specific structure that stipulates the lowest thermal conductivity rate and the least water absorbing compared to other heat insulation materials.
Polyurethane foam popularity is explained by the simplicity of their obtaining process right at their application place. This is possible due to the fact that the charge stock for polyurethane foam are liquid materials of various viscosity rate; when mixing them, a chemical reaction of polymer fusion takes place; the polymer simultaneously frothers and a gaseous medium is created (evaporates).
Elastic semi-rigid and rigid materials are manufactured from polyurethane foam. Polyurethanes are processed almost with all existing engineering methods - extrusion, pressing, casting, moulding, sputtering, etc. Absolutely all known construction materials and products types are obtained from polyurethane: filled, clad, frothed, laminated and other types in the form of plates, sheets, blocks, profiles, fibers, skims; products and constructions from polyurethane are also used in absolutely all industry branches.
Due to a possibility of receipt changes in polyurethane foam properties, it is possible to use them for heat insulation of industrial and civil buildings, constructed from ferroconcrete blocks, brick and other materials, for heat insulation and doorways and window openings compression, as well as heat insulation of any type of a conduit.
Another very interesting technology application area is insulation and waterproofing building roofs. Polyurethane foam application here makes it possible to cover roofs of any configuration without a single joint. It is possible to apply the material both onto new constructions and onto old ones covered with metal, ruberoid or roofing slate. It is not obligatory to dismantle old cover or to conduct any kind of first workings.
ADVANTAGES OF SPRAYED POLYURETHANE FOAM
1. Polyurethane possesses high adhesion; it could be sprayed over practically any kind of material: wood, glass, metal, concrete, brick, and paint, irrespective of the surface configuration. Thus, no special isolation fixing is needed. Besides, polyurethane foam cover is inert towards acid and alkaline mediums; it works in soil, and can be used as roof material. The only thing that polyurethane foam requires is protection from direct sunlight. The cheapest protection is painting the sprayed polyurethane.
2. Rigid sprayed polyurethane is used as heat insulation and protection covers of power equipment, conduits, cumulative tanks, chill boxes and other building constructions.
3. Rigid polyurethane has a closed-loop cell structure, filled with freon -11, and possesses rather low heat insulation indexes, which stipulates its good heat insulation properties compared to traditional materials.
The sprayed cover does not require renewing or repairing during the whole life time of a building. Polyurethane foam does not support burning and it is a rather hard-inflammable material.
In construction field, rigid polyurethane foam heat insulation is mainly applied. Due to unique polyurethane foam heat insulation properties (the lowest thermal conductivity rate, environmental safety, durability, acoustic insulation capacity, anti-corrosion protection, very low water absorbing and, finally, high processibility) polyurethane foam is widely applied for heat insulation of: conduits, heat-and-water supply, cryogenic conduits, walls, roofs, cellars, ceilings, attics, dwelling and industrial premises, saunas, steam-houses, and in manufacturing isothermal, freezing wagons and cells, «sandwich»-boards, heat insulation blocks for various purposes, sealing joints between housing panels, door-frames and window casings. This is not at all the complete list of polyurethane foam properties.
POLYURETHANE FOAM SPECIFICATIONS AND PROPERTIES
|Index||Rates for various polyurethane foams|
|Apparent consistence, kg/m||18..300|
|Vursting voltage, ÌPà, not less||under compression 0,15..1,0, when curving 0,35..1,9|
|Thermal conductivity, Vt/m*Ê, not higher||0,019..0,03|
|Closed interstice quantity, not less||85..95|
|Water absorption, % of volume||1,2..2,1|
Among the other heat insulation materials, polyurethane foam possesses the lowest thermal conductivity rate (l=0,022 Vt/m°Ñ) and the best waterproof properties (up to 99% of closed interstice), which allows to used it even as roof material. Polyurethane foam is chemically neutral towards acid and alkaline mediums. Inflammability class - Ã2. Polyurithane foam possesses high chemical compounds resistance.
| Polyurithane foam||0,019 - 0,025|
| Foam||0,056 - 0,098|
| Mineral wool||0,04 - 0,045|
| Expanded polystyrene||0,03 - 0,037|
One of the main ways to use rigid polyurethane foam is the technology of construction heat insulation spraying at the construction site, due to the following properties:
POLYURETHANE FOAM (PF) COMPARED TO OTHER HEAT INSULATION MATERIALS:
- The lowest thermal conductivity rate (0,019-0,028 Vt/m*Ê);
- Little consistence (40-50 kg/m);
- High adhesion solidity;
- No necessity to use fixing elements;
- Good acoustic insulation;
- Absence of chill bridges;
- Capability of insulation of all kinds of constructions.
|Heat insulation material||Consistence rate (kg/m3)||Thermal conductivity rate (Vt/m*Ê)||Sponginess||Service life (years)||Operating temperatures range
|Rigid PF||40-160||0,019-0,025||closed||30||-180.. +180
|Mineral wool||55-150||0,052-0,058||open||5||-40.. +120
Covers are durable: they are not open to decay and corruption, they do not decompose because of season temperature disturbance, atmospheric precipitation, and aggressive industrial atmosphere.
The obtained material possesses high environmental safety: according to hygiene standards, it is permitted for use in refrigerating engineering for cooling provision.
|Inside temperature, °Ñ
||Dew point temperature under inside relative humidity
|45 %||50 %||60 %||70 %||80 %||90 %