Calculation Formula for TDI Consumption

The amount of TDI to be added in the formulation can be calculated using the following procedure and formula. 100 parts by weight of polyol polymer.

A  represents the mass of TDI consumed in completely reacting with the hydroxyl and carboxyl groups of the polyol polymer.

A = 87*100/56*1000*(Acid Value of the polyol polymer}+ Hydroxyl Value)

=0.1554 * (Acid Value of the polyol polymer}+ Hydroxyl Value)

B  represents the mass of TDI consumed in completely reacting with the water in the system (including both the water in the formulation and the water present in the reactive components).

B = 174/84*Water %

=9.667*Water %

C is the total mass of TDI consumed by the hydroxyl groups, carboxyl groups, and water in the polyol polymer, calculated based on the equivalent weight. This represents the theoretically required mass of TDI for chemical equivalence.

C = A + B

The actual amount of TDI to be used is calculated as follows:

Actual TDI Amount = (A+B)*Isocyanate Index

Example Calculation:

For 100 parts by weight of polyethylene adipate, with a hydroxyl value of 56, an acid value of 0.5, and negligible water content, and an additional water content of 3.0 parts by weight in the formulation. Assuming the TDI index is set to 1.05, the required amount of TDI in the formulation is calculated as follows:

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