Calculation in Polyether Polyol Synthesis

Polyether polyols are synthesized using initiators and alkylene oxides as primary raw materials. The synthesis can use either single or mixed initiators and can involve a single alkylene oxide like propylene oxide (PO) or a mixture of alkylene oxides. The following provides a brief overview of the calculations related to raw material ratios and basic structural parameters of polyethers.

1. Calculation Examples

1.1 Single Initiator Polyether Formulation Calculation

Example 1: Hard foam polyether polyol production using propylene oxide (PO) and ethylenediamine (EDA) as raw materials. Given a required mole ratio of EDA=1:6 and a batch production of 2000 kg, calculate the input quantities of PO and EDA, the molecular weight of the polyether product, and the theoretical hydroxyl value.

Calculation:

Mass ratio of EDA to PO:

m(EDA):m(PO)=(1×60.1):(6×58.1)=1:5.80

EDA input quantity:
EDA input quantity=2000/(1+5.8)=294 kg

PO input quantity:
PO input quantity=294x5.80=1706(kg)

Theoretical molecular weight of polyether:
60.1+58.1x6=409

Theoretical hydroxyl value:
(4x56100)/409=549(mgKOH/g)

"K value":
"K value"=moles of PO/f=64=1.5

Example 2: A soft foam polyether is produced using glycerol as the initiator, copolymerized with PO and a small amount of ethylene oxide (EO), with a designed product molecular weight of 3000 and an EO mass fraction of 10%. Given a batch production of 10 tons, calculate the hydroxyl value of the polyether, input quantities of raw materials, and molar ratios of the materials.

Theoretical functionality for the glycerol initiator is 3.

Hydroxyl value of polyether:
=(56100x3)/3000=56.1(mgKOH/g)

Glycerol input quantity:
(92.1/3000)x10000=307(kg)

Glycerol mass fraction:
307/10000=3.07(%)

PO input quantity:
10000x(1-10%-3.07%)=8693(kg)

EO input quantity:
10000x10%=1000(kg)

Molar ratios of glycerol:PO:EO:
(307/92.1):(8693/58.1):(1000/44.1)=1:44.9:6.8

1.2 Mixed Initiator System

Example 3: A hard foam polyether uses a mixed initiator system consisting of toluenediamine (TDA) and triethanolamine (TEA), copolymerized with PO and EO. Given a mass ratio of the initiators m(TDA)

(TEA) = 2:1, a mass ratio of mixed initiator to mixed monomer of 1:3, and an EO mass fraction w(EO) = 3.67%, calculate the apparent functionality and apparent molecular weight of the mixed initiator, the input quantities of each component, the molecular weight of the product, and the hydroxyl value (with a batch production of 16800 kg).

Calculation:

Molar ratio (mole fraction) of TDA to TEA:
n(TDA):n(TEA)=(2/122.2):(1/149.2)=0.71:0.29

Apparent functionality of mixed initiator:
F=4x0.71+3x0.29-3.71

Apparent molecular weight of mixed initiator:
ME=122.2x0.71+149.2x0.29-130

Total input quantity of mixed initiator:
16800X1/(1+3)=4200(kg)

Total input quantity of monomer:
16800X3/(1+3)=12600(kg)

TDA input quantity:
m(TDA)=4200X2，(2+1)=2800(kg)

TEA input quantity:
m(TEA)=4200X1/(2+1)=1400(kg)

EO input quantity:
m(EO)=16800X3.67%-616(kg)

PO input quantity:
m(PO)=12600-616=11984(kg)

Molar ratios of mixed initiator to EO and PO:
n(mixed initiator):n(EO):n(PO)=(4200/130):(616/44):(11984/58)=1:0.433:6.39

Molecular weight of polyether (Mn):

130+0.433x44+6.395x58=520

Hydroxyl value of the product:
3.71x56100/520=400.2(mgKOH/g)