PUR vs. PIR: Know the Difference

Insulation panels PIR (Polyisocyanurate)
Insulation panels PIR (Polyisocyanurate) are systems for continuous lamination lines for the production of sandwich panels (refrigerators, isothermal chambers, industrial insulation)

Close relatives share a family history, but rarely have the same personality. Insulation is similar in that PUR and PIR are close in chemical composition but vary in performance. While their composition makes them different, some properties that make them similar are that they both are lightweight with low thermal conductivity, and, therefore, help improve the energy efficiency of buildings by significantly reducing energy needs associated with heating and cooling.

PUR foams are essentially made by reacting a “polyol” component and an “iso” component in which the OH groups of the polyol component chemically balance the NCO groups of the iso component and form urethane linkages. In PIR foams, the iso components react with each other in trimerization reactions to form isocyanurates. Excess iso reacts with polyol to form urethane linkages as well.

Anyone who makes insulation boards for cold storage will know about polyurethane insulation boards. So here we will introduce PIR foam and PUR foam to everyone,
PIR
PIR, full name Polyisocyanate Foam, Chinese name is “polyisocyanate”, also known as “polyisocyanurate”, also known as “polyisocyanurate foam PIR” or “tri polyester PIR”. PIR is a kind of foaming material made by reacting isothio cyanate with polyether through catalyst, which has better physical and fire resistance than ordinary polyurethane. It is an ideal organic low-temperature insulation material with low thermal conductivity, lightweight shock resistance, and strong adaptability. Widely used for thermal insulation in refineries, chemical plants, ethylene, fertilizers, cold storage, and construction industries. Also known as a protein database.
PUR
PUR, full name Polyurethane (polyurethane), is a polymer with carbamate chain segment repeating structural units, which is made by the reaction of isocyanate and polyol. It has excellent material performance, wide applications, and a wide variety of products, among which PUR foam is the most widely used. PUR products are divided into foam products and non foam products. Foam products include soft, hard and semi hard PUR foam plastics; Non foaming products include coatings, adhesives, synthetic leather, elastomers, and elastic fibers.
PIR performance is superior to PUR
The fire resistance of 1PIR is superior to that of PUR and the mechanism behind the difference in fire resistance performance:
PUR and PIR are two foam systems. Polyols are divided into polyester polyols and polyether polyols. PUR is a foam system formed by the reaction of polyether polyols and isocyanates. PIR is formed by the reaction of polyester polyols and isocyanates. The isocyanate index of PUR board is usually between 110 and 120, and the crosslinking degree of PUR foam system mainly depends on the functionality of polyether polyol. However, with the increasingly strict requirements for fire rating, PUR foam is facing a huge challenge in the fire prevention specification. Usually, in order to meet the requirements of fire prevention specifications, a large number of flame retardants will be added to the formula system, but at the same time, it will affect the compression strength, dimensional stability and other physical properties of foam, and increase the cost of the product.
The degree of crosslinking of PIR system depends on the trimerization of excessive isocyanate. Generally, the isocyanate index reaches 200~300. Under the action of the corresponding catalyst, the excessive isocyanate can self react to form six membered rings, provide crosslinking for the foam collective, and at the same time promote combustion and coking through its own six membered ring molecular structure, so as to improve the fire resistance of the foam system

2. PIR reaction is simple and can use low-cost raw materials
   3 PIR can provide products with better high and low temperature dimensional stability, lower thermal decomposition rate, and form a protective carbon layer during the combustion process
3. The mechanical strength of PIR is better than that of PUR
   The production efficiency of 5 PIR is relatively high.
   The shortcomings of PIR compared to PUR
4. High brittleness, lower fluidity than PUR
5. Poor adhesion, with a bonding force of only 1/2 of PUR to the painting material
   3 PIR has a rapid secondary foaming performance, which can affect the surface performance of the board
6. Poor surface ripening, late post ripening
   The process range is relatively narrow (production temperature above 60 ℃), making production difficult to control. In the continuous PIR sheet production, the control of equipment and external environment is crucial to the quality of the final product. It is necessary to conduct good temperature control for various chemical raw materials, because it has a huge impact on the stability of the entire chemical reaction process and the entire foam forming process

The creation of PUR and PIR

PIR and PUR are both derived from , a plastic material invented by German scientist Otto Bayer and his colleagues in 1937. In 1954, the accidental introduction of water resulted in rigid polyurethane (PUR).

Just 13 years later in 1967, scientists improved upon PUR’s thermal stability and flame resistance to create polyisocyanurate (PIR). In order to create the new type of insulation, scientists induced a chemical reaction at a higher temperature.

The foaming of PUR and PIR occurs with the use of expanding agents: freon, pentane, HFC 245fa, CO2 or water. Additives whith spraying PUR and PIR foams can be used: flame retardants, fillers, dyes, chain extenders, free fluorine gas agents.

PUR was the most prone to decarbonylation (=release of CO), followed by ether PU and PIR.

Which products are suitable for the production of insulation materials?
Sustainability and resource conservation are becoming increasingly important to consumers and manufacturing companies. Consumers are looking for household appliances with the highest possible energy efficiency and for building insulation to save heating energy. It is therefore not surprising that the market for insulation and thus insulating materials is growing.

Two of the key industrially produced insulation materials are made of Polyurethane (PU) and Polystyrene (PS). In order for these to have an insulating effect, they must first be foamed. For this purpose, there are Pentanes on the one hand, and Fluorinated Olefins (HFOs) on the other. Both, but especially the Pentanes, have replaced the partially halogenated hydrocarbons (HCFC), which are particularly harmful to the environment. The alternatives to these two products are only suitable to a limited extent or are not yet available on a large scale.

Although chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are no longer permitted in the EU under the Montreal Protocol, HFOs may still be used. In contrast to pentanes, they are not equally available worldwide because they have to be manufactured in a complex way, which only very few manufacturers are able to do. This effort is also reflected in the price. Pentanes and HFOs can be mixed to optimise costs and foam properties, especially energy efficiency.

The production of insulation materials with Pentanes
Pentanes have long been used as blowing agents in Polyurethane (PU) and Polyisocyanurate (PIR) formulations. They have a proven track record and now account for more than 50% of the global market share.

Advantages of Pentanes and Pentane Blends:

High performance
No measurable ozone depletion potential (ODP)
Low impact on global warming (GWP) compared to other blowing agents
Three different isomers can be found on the global market: n-Pentane, iso-Pentane and Cyclopentane. All three have physical differences and are therefore chosen for different applications in the field of insulation.

Based on the polyol components, rigid PUR/PIR foams were produced in the laboratory by mixing 0.3 dm 3 of a reaction mixture in a paper cup. To this end, the respective polyol component, the flame retardant, the foam stabilizer, catalysts and c/i-pentane (30:70) as blowing agent were added and the mixture was stirred briefly.

The benefits of PUR

PUR insulation can be injected into wall cavities to create an energy efficient barrier. The foam is able to reach small spaces to create an air-tight seal. According to the , PUR provides “the best thermal performance of all practical full cavity insulants.”

PUR foam can be continuously sprayed onto any type of surface. It is generally less expensive than other materials, making it ideal for renovations.

In flood prone areas, PUR’s high water resistance can minimize the impact of water damage in wall cavities, since it is a material that does not hold moisture.

The benefits of PIR

Despite PUR’s benefits, PIR insulation builds upon them. PIR (polyisocyanurate), typically cut into boards, can be used in insulated metal panels, wall cavities and as insulated plasterboard. PIR has such a , it requires only half the thickness of other mineral-based insulation products.

PIR, like PUR, is known for use as a low-moisture barrier. The most notable differentiating factor for PIR is its . PIR slows the spread of flames and reduces the smoke emitted from the fire when compared to PUR products.

The future of insulation

While PIR and PUR have been used for decades, there’s another advanced insulation that outshines both in fire protection and thermal performance.

With 11 percent better thermal performance than PIR and up to 60 percent improvement over PUR, it is unrivaled in the market. Its fire resistance meets the highest insurance and regulatory standards.

The overall performance of pentane blown rigid polyurethane foams in terms of insulation value and mechanical properties is demonstrated. The low vapor pressure of both normal-pentane and cyclopentane is shown to induce condensation effects. The consequences of condensation in terms of thermal conductivity and dimensional stability are discussed. The effects on the cell gas pressure of the pentane solubility in the polymer matrix are demonstrated and compared with sorption measurements. The solubility is shown not to deteriorate the foam mechanical properties as a function of time. The ageing characteristics of normal -and cyclopentane blown laminates in terms of the thermal insulation value are discussed. Mixtures of normal- and cyclopentane are suggested to be advantageous in view of their ageing profile.