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September 13, 2023Global MDI Market Snapshot
Methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI) are primarily used in the production of polyurethanes. Compared to other polymers such as polyethylene, polypropylene, or PVC, polyurethane is unique. While the other polymers have a basic backbone of repeating units, polyurethanes cannot be characterized as such. It is easier to define polyurethanes as polymers containing urethane monomer units in their backbone, as well as other functional units such as esters, ethers, amides, ureas, and isocyanurate groups.
TDI was the first of the aromatic diisocyanates to be introduced commercially for use in polyurethane flexible foam manufacture. It is available as a mixture of two isomers, the 2, 4 and 2, 6 isomers, with the most common grade made up of 80 percent 2, 4-TDI and known as 80:20 TDI. This grade is typically used in the production of polyurethane foams and polyurethane CASE applications. 65:30 TDI and 100 TDI are also available and used in the production of high resilience flexible foam and CASE applications, respectively.
MDI was developed in response to the problems caused by the volatility of TDI. TDI has a higher volatility, and in confined areas, sprayable TDI foams were difficult to handle by workers and led to health issues. The number of transformation steps from initial refined feedstock to MDI is higher than TDI, and the chemistry used is more complex. MDI is principally used in polyurethane and polyisocyanurate foam for construction or appliance insulation but is also used in automotive foam, coating, adhesives, sealants, and elastomers.
Methylene diphenyl diisocyanate (MDI) is produced in monomeric, polymeric, and modified forms. There are two commodity grades of MDI that are commonly sold – monomeric MDI and polymeric MDI. There is a significant variety in the types of modified MDI and MDI prepolymers sold to the market and they are considered specialty as they are sold on their performance. Crude and high functionality polymeric MDI (HFPMDI) are essentially variants of polymeric MDI with higher and lower monomeric MDI content, respectively. Blending of MDI components is also possible to produce products with specific properties.
There are three properties that are key to choosing one of the commodity MDI grades – NCO content, viscosity, and functionality. NCO content is a measure of the amount of free isocyanates as a function of the total molecular weight and functionality of the isocyanate and polyol. Functionality is defined as the number of isocyanate groups per MDI molecule. Viscosity is an important measure for processing but is also an indicator of the monomeric MDI content of the product. Functionality of monomeric MDI is two – as there are two isocyanate groups available to react on the 4,4-MDI molecule. The functionality of polymeric MDI is between 2 and 3 as the oligomeric species tend to cross-link by various side reactions. This allows for greater cross-linking in polyurethanes which enhances the rigidity of the final product.
Total global MDI consumption is estimated to increase to 7.5 million tons in 2023, a two percent increase from 2022. MDI consumption is closely linked to performance in the construction and appliance sectors which have stagnated through 2022 and 2023 due to inflation. Demand growth is expected to remain stagnant through 2024 but improvements depend on the lowering of interest rates to help buoy demand growth.
MDI production is highly concentrated in three major regions: North America, Western Europe, and China. Global MDI capacity in 2023 exceeds 10 million tons per year, with the number of producing companies limited. The top five producers account for nearly 90 percent of total global capacity, with Wanhua the largest global producer. Wanhua Chemicals has large MDI capacity addition plans in China until 2025 and has also added new capacity since 2022.
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Our Market Analytics: Isocyanates - 2023 report provides analysis and forecasts to 2045 of supply and demand of the global isocyanates markets. This analysis identifies the issues shaping the industry as well as provides global capacity listings, with long term demand, supply and net trade forecasts for 40 countries.
Products analysed in detail include nitrobenzene, aniline, methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI).
Each product is available as a separate report, in addition we also have technology focused reports covering MDI, TDI and nitrobenzene and aniline.
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