{"id":1768,"date":"2021-09-25T09:05:01","date_gmt":"2021-09-25T09:05:01","guid":{"rendered":"https:\/\/eiel.ee\/polyurethane-pur-as-an-insulation-material\/"},"modified":"2025-07-03T00:23:45","modified_gmt":"2025-07-03T00:23:45","slug":"polyurethane-pur-as-an-insulation-material","status":"publish","type":"page","link":"https:\/\/eiel.ee\/en\/polyurethane-pur-as-an-insulation-material\/","title":{"rendered":"Polyurethane (PUR) as an insulation material"},"content":{"rendered":"\t\t
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Polyurethane (PUR) as an insulation material<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Polyurethane, or PUR, is a polymer formed by the reaction of isocyanate and polyol. Polyurethane is used in a wide range of different products and its properties can vary widely; its specific weight varies from 8\u20131200 kg\/m3; polyurethane can have either open or closed pores; polyurethane can be hard or soft, elastic or even brittle. There are also a wide range of applications: PUR can be used to make load-bearing structures for furniture, soft seat cushions, interior car upholstery, seats and steering wheels. Polyurethane is also used to make paints, varnishes, and assembly foams.<\/p>\n

In industrial insulation, polyurethane is used both in cast-in-place form and as finished products, in the form of enclosures or slabs, mainly for insulating cold surfaces. Its advantage over mineral wool or polystyrene is its significantly better insulating properties and, in the event of PUR cast-in-place, the vapor barrier formed on the inner surface of the cladding, which, if properly executed, ensures a continuous vapor barrier along the entire length of the pipework (tank, equipment). Also, polyurethane insulation, in combination with cladding, is highly resistant to mechanical influences.<\/p>\n

In fact, polyurethane has many different variants, or systems (a system is a set of components that, when mixed in the right proportions, form a foam with specific properties). There are systems with different specific weights and different expansion gas pressures that give different results: Polyurethane with open pores: for example, assembly foams, as well as foams with a specific weight of less than 40 kg, have insulation properties close to polystyrene and wool products, as the pores are filled with air, which does not have very good insulation properties.<\/p>\n

The insulating properties of polyurethane foam with closed pores depend, to a large extent, on the filler gas inside the pores. This gas is formed from an expanding agent, which is a low boiling liquid, such as R11, R141b, R134a, etc. The expanding agent also affects adhesion to surfaces, for example, water, which reacts with isocyanate to form CO2 is a cheap system, but poorly adhesive to many materials below 40 \u00b0C. Moreover, CO2 does not remain in the pores for long but is replaced by air over time.<\/p>\n

CFCs, or chlorofluorocarbons R11 and R12, were banned in 1993.
The use of HCFCs in the manufacture of insulation, such as R141b, was banned in 2000. More recently, pentane or HCFs 365mfc, 245fa, and 365\/227 have been introduced.<\/p>\n

Impact of expanding agent on insulation properties:<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n
<\/td>\n<\/td>\n\n

24h old<\/p>\n<\/td>\n

\n

3 weeks old<\/p>\n<\/td>\n

<\/td>\n<\/tr>\n
\n

Expanding agent<\/p>\n<\/td>\n

\n

Density<\/p>\n<\/td>\n

\n

\u03bb10W\/mK<\/p>\n<\/td>\n

\n

\u03bb10W\/mK<\/p>\n<\/td>\n

<\/td>\n<\/tr>\n
\n

Pentane<\/p>\n<\/td>\n

\n

35-40<\/p>\n<\/td>\n

\n

0,020<\/p>\n<\/td>\n

\n

0,021<\/p>\n<\/td>\n

\n

with closed pores<\/p>\n<\/td>\n<\/tr>\n

\n

HFC-245fa<\/p>\n<\/td>\n

\n

45-60<\/p>\n<\/td>\n

\n

0,020<\/p>\n<\/td>\n

\n

0,021<\/p>\n<\/td>\n

\n

with closed pores<\/p>\n<\/td>\n<\/tr>\n

\n

HFS-365mfc<\/p>\n<\/td>\n

\n

45-60<\/p>\n<\/td>\n

\n

0,021<\/p>\n<\/td>\n

\n

0,022<\/p>\n<\/td>\n

\n

with closed pores<\/p>\n<\/td>\n<\/tr>\n

\n

CO2\/water <\/p>\n<\/td>\n

\n

45-60<\/p>\n<\/td>\n

\n

0,023<\/p>\n<\/td>\n

\n

0,030<\/p>\n<\/td>\n

\n

with closed pores<\/p>\n<\/td>\n<\/tr>\n

\n

CO2\/water <\/p>\n<\/td>\n

\n

28<\/p>\n<\/td>\n

\n

0,028<\/p>\n<\/td>\n

\n

0,034<\/p>\n<\/td>\n

\n

with partially closed pores<\/p>\n<\/td>\n<\/tr>\n

\n

CO2\/vesi<\/p>\n<\/td>\n

\n

14<\/p>\n<\/td>\n

\n

0,034<\/p>\n<\/td>\n

\n

0,037<\/p>\n<\/td>\n

\n

avatud pooridega<\/p>\n<\/td>\n<\/tr>\n

\n

CO2\/water <\/p>\n<\/td>\n

\n

8<\/p>\n<\/td>\n

\n

0,041<\/p>\n<\/td>\n

\n

0,041<\/p>\n<\/td>\n

\n

with open pores<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/tr>\n
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these details are valid at +10 \u00b0C  <\/p>\n<\/td>\n

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The shape of the pores also has an effect on the properties of PUR: round pores give a stiffer foam, while elongated pores give a softer and more shrinkable foam.<\/p>\n

Industrial insulation mainly uses diphenylmethane-4,4-diisocyanate (MDI) and a polyether polyol blend, which provides a hard polyurethane with closed pores. In addition to the two main components, the mixture also contains an expanding agent, an activator, a stabiliser, and other additives, such as flame retardants.<\/p>\n

The use of cast-in-place PUR as insulation has advantages over other insulation materials, namely:<\/p>\n