Polyurethane Foam and Polyisocyanurate Foam Systems

Polyurethane Foam (PUR) and Polyisocyanurate Foam (PIR) Systems Polyurethane (PUR) foams are formed as a result of the exothermic reaction between diisocyanates and polyols. During this reaction, the nitrogen (N) atom found in isocyanates bonds with the hydrogen (H) atom in the hydroxyl (OH) groups present in polyols. The same reaction applies to polyisocyanurate (PIR) foams. However, in PIR systems, the isocyanate index relative to polyol is higher than in PUR systems and shows stoichiometric differences. In PUR systems, approximately one polyol corresponds to one isocyanate, meaning an index of 1:1, whereas in PIR systems the amount of isocyanate is significantly higher with an index of 1:2 (polyol:isocyanate). The excess isocyanate in PIR systems causes the isocyanates to close among themselves and undergo trimerization. Figures 1a and 1b show the chemical structures of PUR and PIR systems respectively (1). Although both foam types are used for thermal insulation purposes in panel systems, each has its own advantages and disadvantages. Since the isocyanate index used in PUR systems is lower than in PIR systems, it is more cost-effective, but PIR systems are more effective in terms of flame-retardant properties. According to TS EN 13501-1, the flammability classification is B, C, D, s3, d0 for PUR systems and B, s2, d0 for PIR systems (2). Table 1 presents the groups and their equivalents in TS EN 13501-1 standards (3). Additionally, PIR foams easily conform to the shape of the surface where they are applied and can be applied conveniently. As Baymel Kimya Yapı A.Ş., by using recyclable polyols, we provide raw material options suitable for use in both systems. Our Research and Development Center continues its activities with years of experience in accordance with requested requirements. While offering various opportunities with economical and diverse product range, we produce innovative solutions with innovative approaches.

References

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 Research and Development Center Manager Baymel Kimya Yapı A.Ş. Erhan Altıntuğ Chemist Baymel Kimya Yapı A.Ş.