Polyurethane (PUR) Foam and Polyisocyanurate (PIR) Foam Systems
Polyurethane (PUR) foams are formed as a result of the exothermic reaction of diisocyanate and polyols. During this reaction, the nitrogen (N) atom in isocyanates is bonded to the hydrogen (H) atom in polyols in the hydroxyl (OH) group.
The same reaction applies to the polyisocyanurate (PIR) foams as well. However, the isocyanate index corresponding to the polyol in PIR systems is higher than in PUR systems and alters stoichiometrically.
In PUR systems, approximately one polyols corresponds to one isocynate, where its index is 1:1, whereas in PIR systems, the amount of isocyanate is higher and its index is 1:2 (polyol:isocynate). In PIR systems, the excess of isocyanate causes to shut down isocyanate and trimerization. The chemical structures of PUR and PIR systems are shown in Figure 1a and Figure 1b, respectively.
Although both foam forms are used for thermal insulation in panel systems, they have their own advantages and disadvantages. Since the isocyanate index used in PUR systems is less than PIR systems, they are olw cost, but PIR systems are more effective in terms of fire retardant feature.
According to TS EN 13501-1 as non-flammability class, PUR systems are B, C, D, s3, d0 while PIR systems are B, s2, d0 (2). The classifications in the TS EN 13501-1 standards and their equivalents are given in Table 1 (3).
Additionally, PIR foams easily cover the shape of the surface in terms of the application area and can be applied easily.
As Baymel Kimya Yapı A. Ş., we offer suitable raw materials for use in both systems by using recyclable polyols. Our R&D center continues its activities with years of experience
in line with the demands. While offering various opportunities with its economical and different product range, we produce innovative solutions with innovative approaches.
Source
1. https://www.turkchem.net/flame-retardant-kimrigid-pir-systems.html
2. https://www.emcelectronic.com/uploads/dosya/TSE_EN_13501-1.pdf
3. http://catider.org.tr/pdf/sempozyum9/18-YANGIN%20EMN%C4%B0YET%C4%B0%20ve%20CEPHE%20TASARIMI.pdf
4. https://iopscience.iop.org/article/10.1088/1755-1315/90/1/012187/meta
5. https://www.keskinso.com/Haber/1023/Pir-and-Pur-Poliuretan-Sandvic-Panel-Ozellikleri.html
Dr. Özden Demircioğlu
R&D Center Manager
Baymel Kimya Yapı A.Ş.
Erhan Altıntuğ
Chemist
Baymel Kimya Yapı A.Ş.
