Toughness Durability Chemical resistance Thermal stability MDI-based Polyether Polyurethane Prepolymer For Coatings Adhesives And Elastomers

MDI Based Polyurethane CAS 9009-54-5 Shore A85

1. Description

MDI-based polyether polyurethane prepolymers are synthesized by reactingmethylene diphenyl diisocyanate (MDI), a commondiisocyanate with two highly reactiveisocyanate groups (-NCO), withpolyether polyols (typicallydiols ortriols with hydroxyl end groups) under controlled conditions. This reaction forms aprepolymer withisocyanate (NCO) end groups or, in some cases,hydroxyl (OH) end groups, depending on the stoichiometry and catalysts used. The process often involvesdehydrating the polyether polyol to remove moisture, conducting the reaction under nitrogen to prevent side reactions, and carefully controlling temperature to manage viscosity and reaction rate.

2. Characteristics

These prepolymers are characterized by their high reactivity, especially when containing free NCO groups, which readily react withwater (formoisture-curing systems) oractive hydrogen compounds like alcohols oramines during curing. They are typically available as viscous liquids or solids and are designed for low monomeric MDI content to enhance safety and reduce volatility.

Performance advantages include excellent adhesion to various materials,flexibility, andlong-term durability under harsh conditions such as exposure to solvents, moisture, or temperature fluctuations. Thepolyether backbone contributes tohydrolytic stability andlow-temperature performance. ‌Safety considerations involve handling with protective equipment due to thereactivity of NCO groups with moisture and skin, and storage in sealed,non-reactive container.

3. Applications

Adhesives‌: Used inreactive hot melt systems for automotive, construction, or packaging, where rapid curing and strong bonding to diverse substrates (e.g., metals, plastics) are needed. ‌

‌Coatings‌: Applied in industrialprotective coatings for machinery, pipelines, or floors due to theirabrasion resistance andchemical durability. ‌

‌Seals and gaskets‌: Formulated intoelastomers with highflexibility andload-bearing capacity (e.g.,Shore hardness 85A), suitable for dynamic environments like automotive engines or hydraulic systems. ‌

‌Industrial components‌: Used inmolding processes for parts requiringimpact resistance andthermal stability.

4. Typical properties

5. Operating Procedure

First, the prepolymer should be preheated in 80-85℃. Second, after vacumming, the prepolymer is to be mixed with melting MOCA evenly. Third, with degassing, casting into mould, and vulcanization,and then demould. Lastly, the finished product should be post vulcanized.

6. Reaction parameters

7. Finished products properties