The first commercial applications of polyurethanes were developed in the mid-20th century. Since then, their use has increased in industries such as construction, automotive, refrigeration, furniture and footwear. Polyurethanes are extremely versatile and can be found in many everyday items around us.
Rigid polyurethane (PUR) and polyisocyanurate (PIR) insulation products are highly efficient, lightweight, and able to adhere to most materials. Their excellent thermal conductivity and high strength-to-weight ratio, combined with outstanding manufacturing versatility, offer a range of products.
As a result, PIR and PUR insulation products are the natural choice for most building insulation applications.
Rigid PUR insulation products are manufactured by reacting a liquid polyol component with a liquid polymeric isocyanate component, diphenylmethane diisocyanate (MDI), in the presence of a blowing agent and other additives. The blended components then react exothermically to form a rigid thermosetting polymer, and as the blowing agent evaporates during the exothermic reaction, a closed-cell, low-density rigid insulation product is formed. Excellent thermal insulation is achieved due to the very low thermal conductivity of the gases trapped in the closed-cell structure and minimal heat conduction through the solid pore walls due to the low density, with approximately 97% of the foam volume being trapped gases.
Rigid PIR differs from PUR in that it is produced using an excess of the MDI component. In the presence of an appropriate catalyst, the excess MDI reacts with itself to form an isocyanurate, which is characterized by increased thermal stability. The resulting PIR insulation products exhibit higher fire performance, lower flammability and higher operating temperature limits than PUR and, when incorporated into building products, can meet some of the most demanding fire performance requirements, such as those currently dictated by the insurance industry for certain applications.
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