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Knowledge of Modified MDI
Updated: 2017-09-25 13:07 Source: PUWORLD share:
PU WORLD--The MDI system includes many well-known products such as pure MDI, polymeric MDI, liquefied MDI and MDI50, as well as MDI pre-polymer which may not sound that familiar to us for it is often recognized as modified MDI on the market.

Modified MDI is the popular name for MDI that has undergone modification in the China market, although its definition has not been clearly made. Modified MDI can be roughly classified into 3 types.

1. Carbodiimide-modified MDI, also called liquefied MDI or monomer modified MDI. It is the product of pure MDI’s self condensation with carbodiimide groups (-N=C=N-) formed for the convenience of storage, transportation and processing. It is often used for molding, and production of integral skin foam and footwear material.

2. MDI-50. This kind of modified MDI is the mixture of 50% 4-4MDI(pure MDI) and 50% 2-4MDI, commonly used in runways, adhesive and coatings systems.

3. MDI pre-polymer. It is a semi-processed product from the termination by NCO groups of carbamate which comes as the combination of active hydroxyl, mercapto group and amino or as the result of reaction between polyether and excess MDI. It can be used for production of auto models, furniture, adhesive and elastomer, depending on its raw material.

Modified MDI has a wide range of names. Codes unique to a producer are often used to avoid confusion.

Brands of Modified MDI by Producer in China

Domestic MDI producers in China produce all the above types of modified MDI. Liquefied MDI contains over 90% pure MDI and is only applied in the downstream sectors as auxiliary feedstock. Its production and demand are limited.

MDI50 is now in serious shortage in the market with surging prices, as standards for construction and testing of plastic racetracks have been raised up and the construction season came in July-August in terms of school racetracks.

MDI pre-polymer is not a regular standard product with a less transparent market. The supply end is complex since every producer has a diversity of product code and can adjust their formula to meet the requirements in different application fields. So the market is featured by huge disparities in product performance and prices.

Currently, MDI pre-polymer accounts for less than 10% percentage of the MDI system. Wanhua and Huntsman undoubtedly hold the biggest share in the domestic market, with more than 50% supply combined. Considering the variety of polymer formulas and wide applications, Wanhua is accelerating its capacity expansions of polymers in Zhuhai, while Huntsman and Tosoh focus more on their production in Shanghai. In addition, non-MDI producers like INOV, Huafon start to supply MDI polymers to the downstream companies while purchasing MDI and producing polymers for internal consumption.

In recent years, domestic polymer production is on the increase with slower import and faster export. Middle East and Middle-South Asia markets report growing demand.

Supply of Modified MDI in 2016 can be seen in the following graph.

Supply of Modified MDI by Producer in China 2016

 (Source: Orisage)

The MDI system is attached with more importance thanks to its high reactivity and low emission of VOC, but MDI’s difficult process forces MDI pre-polymer to come up as a replacement. It can be directly used by downstream manufacturers after being modulation based on formulas and put into molds. MDI pre-polymer can be widely applied in the CASE fields, including auto molding, bedding and furniture foam, shoe sole, elastomer and adhesive. More information in the chart below.

Downstream Consumption of MDI Polymers 2016

 (Source: Orisage)

With the background of tighter environmental regulations, products like MDI-based waterborne PUD are getting more and more popular among the downstream players.

Therefore, modified MDI is growing on both supply and demand, although it is not the major MDI-based product yet due to its low market share. Given that diversification of downstream products requires richer types of MDI pre-polymer with better performance, it should be the technologies and after-sales services that determine a producer’s development due to the lack of transparency in the markets. 


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