How To Choose High-quality TDI2021-02-26

When selecting TDI, we often pay attenetion to its index. But actually, the total chlorine content and hydrolyzed chlorine content of TDI is also important to q

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When selecting TDI, we often pay attenetion to its index. But actually, the total chlorine content and hydrolyzed chlorine content of TDI is also important to quality.
 
In the polyurethane synthesis process, the acid and basic substances in the system will have some additional catalytic effects on the synthesis reaction.
 
In the industrial production of TDI, despite the multiple purification processes, there will still be a certain amount of acid chloride remaining in the product, and its content will directly affect the products’ total chlorine content and change the acidity of raw material.
 
High content of acid chloride will cause TDI to be acidic, which is conducive to its chain extension reaction. But it will cost too much expensive catalysts and is not beneficial to product performance.
 
Therefore, the content of acid chloride and total chlorine of TDI should generally be controlled below 0.01% and 0.1%.
 
But if the acid chloride content is too low, the polyurethane chain extension reaction will have a tendency to accelerate, even worse, it will appear gel quickly.
 
Such case often occur in the production of cast polyurethane rubber and coatings.