Content
Technical Key Points for Adjusting the Isocyanate Index
The Isocyanate Index refers to the ratio of the amount of isocyanate actually used to the amount of isocyanate theoretically required for complete reaction. It is a core parameter for controlling curing speed and crosslinking density.
1. Basic Definition and Principle
Definition: Isocyanate Index = (Actual NCO content used) / (Theoretical NCO content required for complete reaction) × 100%.
Principle: NCO (isocyanate group) is the driving agent for resin curing. NCO reacts with hydroxyl groups (OH) in the resin to form a crosslinked structure.
2. Adjusting Curing Speed
Increasing the Isocyanate Index (>100%): Excess NCO is used. The advantage is extremely fast curing speed, suitable for rapid baking processes or thick coatings. The disadvantage is high reaction heat, which may lead to charring of the resin surface.
Lowering the Isocyanate Index (<100%): Insufficient NCO is used. The curing speed slows down, suitable for scenarios requiring a long working window, such as segmented curing of complex vehicle body structures.
3. Adjusting Crosslinking Density
High Isocyanate Index: High degree of crosslinking, high resin hardness, good chemical resistance and heat resistance, but toughness may be reduced.
Low Isocyanate Index: Low degree of crosslinking, low resin hardness, good flexibility, but chemical resistance and durability may be affected.
4. Jiangsu BESD's Technical Advantages
As a professional OEM/ODM supplier, Jiangsu BESD New Materials Co., Ltd. possesses:
Precise Proportioning System: Our R&D team uses advanced experimental design (DoE) methods to precisely control the Isocyanate Index within the range of 95% - 115%.
Optimized Crosslinking Agent Formula: We use a patented isocyanate mixture to ensure good chemical resistance even at a low Isocyanate Index.
