Step-by-Step Calculation of TDI Addition in a Formulation
To determine the amount of TDI (Toluene Diisocyanate) needed in a formulation, follow the steps and formulas provided below. Assume a base of 100 parts by weight of polyol polymer.
- 1.Determine A:
A represents the mass of TDI required to fully react with the hydroxyl and carboxyl groups of the polyol polymer.
Formula:
A = 87100/561000*(Acid Value of the polyol polymer}+ Hydroxyl Value)
=0.1554 * (Acid Value of the polyol polymer}+ Hydroxyl Value)
- 2.Determine B:
B is the mass of TDI needed to fully react with the water in the system, which includes both the water in the formulation and any water present in the reactive components.
Formula：
B = 174/84Water % =9.667Water %
- 3.Calculate C:
C is the total mass of TDI consumed by the hydroxyl grou
e theoretical TDI consumption for chemical equivalence.
Formula：
C = A + B
- 4.Calculate the Actual Amount of TDI to Use:
The actual TDI amount needed is calculated using the isocyanate index.
Formula:
Actual TDI Amount = (A+B)*Isocyanate Index
Example Calculation
For a formulation including 100 parts by weight of polyethylene adipate with:
Hydroxyl value of 56
Acid value of 0.5
Negligible water content in the polyol polymer
Additional 3.0 parts by weight of water in the formulation
TDI index set to 1.05
1.Calculate A:
A = 0.1554*(56 + 0.5) = 8.749
2.Calculate B:
B = 9.667*3 = 29.001
3.Calculate C:
C = A + B = 8.749 + 29.001 = 37.750
4.Calculate the actual amount of TDI to be added:
Actual TDI Amount = 37.750 * 1.05 = 39.64
By following these steps, you can accurately calculate the required amount of TDI for your specific formulation needs.
