PIR Continuous Systems

The majority of items used in our homes and workplaces today are made from polymeric materials. As the use of polymeric materials, which provide ease of use in many areas of daily life, increases day by day, it has also brought environmental problems. One of the most important disadvantages of polymeric materials is their low resistance to burning. In the European Union and developed countries, the flammability of polymeric materials is among the most important topics that need to be addressed. By adding various additives to polymers, materials are given flame-retardant (slow-burning) properties [1]. Foams, which are polymeric materials (polymer foams, porous polymers), consist of closed voids (pores, cells) filled with air or a gas [2, 3]. In polymeric foam applications, various polymers such as polyurethane (PU), polystyrene (PS), polyolefin (polyethylene (PE) and polypropylene (PP)), poly(vinyl chloride) (PVC), and polycarbonate (PC) are used. Among these polymers, polyurethanes in particular are preferred more because they are easy to foam, have good mechanical and physical properties, and are inexpensive [2]. The low thermal conductivity coefficient of polyurethane foams makes it ideal and indispensable for insulation. This insulation capability helps protect food from spoilage in sectors such as cold storage rooms and refrigerators, and reduces energy and fuel consumption in building insulation. However, rigid polyurethane foams, which have many application areas such as industrial facilities (tanks, pipes, ships), construction, refrigerators, furniture, and refrigerated vehicles, easily ignite, causing fires to spread rapidly and resulting in significant loss of life and property as a result of the fire. Therefore, to reduce loss of life and property in major fires, improving the flame-resistance properties of polyurethane foam used between panels has become unavoidable today. Sandwich panels used for insulation purposes in the construction industry consist of high-strength, low-density foam filler material filled between two thin metal sheets (Figure 1). The filler material used in panels is important in terms of insulation performance. In panel production, various materials such as polyurethane (PUR), polyisocyanurate (PIR), and expanded polystyrene (EPS) are used as fillers [4].

Figure 1. Sandwich panel core material and cladding material [4]

Polyurethanes are polymers formed by the reaction of alcohols (diols or polyols) containing urethane bonds (-NHCOO-) on the polymer chain [5], having two or more reactive functional hydroxyl groups (-OH) per molecule, and diisocyanate or polyisocyanate containing more than one reactive isocyanate group (-NCO) per molecule [6]. Polyurethanes are polymers formed by the reaction of alcohols (diols or polyols) containing urethane bonds (-NHCOO-) on the polymer chain [5], having two or more reactive functional hydroxyl groups (-OH) per molecule, and diisocyanate or polyisocyanate containing more than one reactive isocyanate group (-NCO) per molecule [6].

Figure 2. Polyurethane reaction

Polyisocyanurate (PIR) foams are formed through the cyclotrimerization reaction of isocyanates. PIR foams are more resistant to burning compared to polyurethane foams and have superior thermal stability. The isocyanurate rings in their structure provide flame-retardant properties. For a given polyol formulation, the higher the isocyanate excess (expressed as isocyanate index), and the higher the concentration of isocyanurate rings in the polymeric foam backbone compared to urethane and/or urea bonds, the better the fire-retardant performance. This results from the high bond energy between the semi-aromatic isocyanurate trimer structure and the urethane bonds. Due to their flame-retardant properties, polyisocyanurate foams are widely used as insulation materials in the manufacture of sandwich panels used in the construction industry [7].

Figure 3. PIR reaction [8]

Advantages of polyisocyanurate (PIR) rigid foams:

• Stable at high temperatures, • Resistant to fire, • Has high thermal insulation properties, • Superior mechanical properties, • High resistance to microorganisms/molds. In our country, B2 and B3 class polyurethane foams, which easily ignite in external facade insulation, are used more than B1 class fire-resistant products. However, with the Regulation on Fire Protection of Buildings coming into effect in the construction sector, requiring external facades in high-rise buildings to be made of non-combustible materials and in other buildings from at least flame-retardant materials, the need for B1 class insulation materials is increasing day by day.

Table 1. TS EN 13501-1 and DIN 4102 standards, classification of building materials according to their behavior in case of fire [9]

The CREAPOL RC 3430/36 polyol formulation developed for PIR continuous systems at Flokser Kimya Research and Development Center is used in metal-faced sandwich panel production in continuous line panel systems. PIR continuous sandwich panels are manufactured by allowing the polyol mixture together with catalyst, auxiliary chemicals and blowing agent to react with isocyanate supplied externally. The PIR product CREAPOL RC 3430/36, according to test results conducted in accordance with TS EN 13501-1 standard, is in B s2 d0 fire-resistance class; and B s1 d0 can be achieved with special applications to be applied to the panel. These values meet the industry's needs with regard to fire-resistance, physical and mechanical properties. The technical properties of CREAPOL RC 3430/36 product and the properties of recommended components for the reaction are given in Tables 2-3. [gallery size="medium" ids="eyJ1cmwiOiJodHRwczpcL1wvd3d3LnR1cmtjaGVtLm5ldFwvd3AtY29udGVudFwvdXBsb2Fkc1wvMjAxOVwvMTBcL3VydW5fYmlsZXNlbi5qcGciLCJ0aXRsZSI6InVydW5fYmlsZXNlbiIsImNhcHRpb24iOiJUYWJsZSAyLiBDUkVBUE9MIFJDIDM0MzBcLzM2IGFuZCBwTURJIHByb3BlcnRpZXMiLCJhbHQiOiIiLCJkZXNjcmlwdGlvbiI6IiJ9,eyJ1cmwiOiJodHRwczpcL1wvd3d3LnR1cmtjaGVtLm5ldFwvd3AtY29udGVudFwvdXBsb2Fkc1wvMjAxOVwvMTBcL3VydW5fYmlsZXNlbl8yLmpwZyIsInRpdGxlIjoidXJ1bl9iaWxlc2VuXzIiLCJjYXB0aW9uIjoiVGFibGUgMy4gQ1JFQVBPTCBSQyAzNDMwXC8zNiBjb21wb25lbnQgcHJvcGVydGllcyIsImFsdCI6IiIsImRlc2NyaXB0aW9uIjoiIn0=,eyJ1cmwiOiJodHRwczpcL1wvd3d3LnR1cmtjaGVtLm5ldFwvd3AtY29udGVudFwvdXBsb2Fkc1wvMjAxOVwvMTBcL3VydW5fYmlsZXNlbl8zLmpwZyIsInRpdGxlIjoidXJ1bl9iaWxlc2VuXzMiLCJjYXB0aW9uIjoiVGFibGUgNC4gQ1JFQVBPTCBSQyAzNDMwXC8zNiBwcm9jZXNzIHRlY2huaWNhbCBwcm9wZXJ0aWVzIiwiYWx0IjoiIiwiZGVzY3JpcHRpb24iOiIifQ=="] Figure 4 contains combustion visuals of CREAPOL RC 3430/36 PIR product in B s2 d0 class and polyurethane (PUR) products in B3 and B2 classes. The test specimen, exposed to flame for 30 seconds, passed the test successfully because the applied flame did not reach the 150 mm measurement line within the test duration.

Figure 4. Combustion tests of PUR products in B3 and B2 classes and PIR product in B1 class

Dr. Nesrin Oğuz Research and Development Specialist Flokser Kimya

References [1]. Yıldırım, S., Çelik, E., 2014, Alev Geciktirici Huntit ve Hidromanyezit Nanopartikül Takviyeli Polimerik Kompozit Kaplamalar, AKÜFEMÜBİD 14 (2014) OZ5762 (387-393). [2]. Saçak, M., Polimer Teknolojisi, Gazi Kitabevi, ISBN 975–8895– 82–6, Ankara [3]. Lee, L.J., Zeng, C., Cao, X., Han, X., Shen, J., Xu, G., 2005, Polymer nanocomposite foams, Composites sciences and technology, 65, 2344-2363. [4]. Wang, Y.C., Foster, A., 2017, Experimental and numerical study of temperature developments in PIR core sandwich panels with joint, Fire Safety Journal 90 (2017) 1–14. [5]. Yang, L.T., Zhao, C.S., Dai, C.L., Fu, L.Y., Lin, S.Q., 2012, Thermal and mechanical properties of polyurethane rigid foam based on epoxidized soybean oil, J Polym Environ, 20, 230–236. [6]. Tu, Y.C., Kiatsimkul, P., Suppes, G., Hsieh, F.H., 2007, Physical Properties of Water-Blown Rigid Polyurethane Foams from Vegetable Oil-Based Polyols, Journal of Applied Polymer Science, Vol. 105, 453–459. [7]. (Bertucelli, L., Fantera, G., Golini, P., US 20150118476 A1: Production of polyisocyanurate foam panels, Dow Global Technologies LLC. [8]. Hejna, A., Kosmela, P., Kirpluks, M., Cabulis, U., Klein, M., Haponiuk, J., Piszczyk, L., 2018, Structure, Mechanical, Thermal and Fire Behavior Assessments of Environmentally Friendly Crude Glycerol- Based Rigid Polyisocyanurate Foams, J Polym Environ (2018) 26:1854–1868) [9]. Güleşen, E., Yılmaz, M. H., Yangın Emniyeti ve Cephe Tasarımı, 9. Ulusal Çatı & Cephe Konferansı 12 - 13 Nisan 2018 T.C. İstanbul Kültür Üniversitesi – Ataköy Yerleşkesi – Akıngüç Oditoryumu.