HIRANUMA APPLICATION DATA

Resins, Oils andFats, Rubber,Adhesives, Paints

Automatic Titrator

Data No.

M9Apr. 19,
2018

Determination of isocyanate (NCO) content
in adhesives

1. Abstract
Synthetic adhesives like hydrophilic macromolecule –Isocyanate type wood adhesives are consisted ofbase compound and cross-linker; the principal components of base compound are macromolecule aqueous
solution or aqueous dispersing element, or those combination. The principal components of cross-linker isisocyanate compounds. The measurement procedure of isocyanate (NCO) content described in this report isstandardized by JIS K 6806. NCO content is determined by the neutralization titration which excess
di-n-butylamine is titrated with hydrochloric acid standard solution after sample and di-n-butylamine are mixedand reacted. A measurement example of potentiometric titration for NCO determination is introduced in thisreport.

2. Configuration of instruments and Reagents(1) Configuration
Main unit：

Hiranuma Automatic Titrator COM series

Electrode：

Glass - Reference electrode GR-522BZ

Option：Buret tip (Tube Type)

Titrant：

0.5 mol/L Hydrochloric acid standard solutionSolvent：

2-propanol (Isopropyl alcohol)

Additive：

Di-n-butylamine - toluene solution(2) Reagents

Dissolve 130 g of di-n-butylamine in dehydrated toluene.

3. Measurement procedure1) Take about 2 g of the sample into Erlenmeyer flask and accurately weigh it.
2) Dispense 25 mL of di-n-butylamine - toluene solution with volumetric pipette.
3) Add stirring bar and close it with a stopper. Gently stir the solution for 15 min with stirrer.
4) Add 150 mL of 2-propanol.
5) Immerse the electrode and titrate with 0.5 mol/L hydrochloric acid standard solution.
6) Measure the blank value by operation of (2) ~ (5) without sample.

4. Measurement conditions and Results
Examples of titration conditions
Measurement of blankCndt No.
MethodBuret No.
Amp No.
D. Unit
S-Timer
C.P. mLT Timer
D.P. mLEnd Sens
Over mL
Max.Vol.

1Auto
11pH
5
45
001000
0.360

sec
mL
sec
mL
mL
mL

ConstantNo.
SizeBlank
Molarity
FactorKL

1000.5
1.005
00UnitFormulaDigits
Auto In Pram.

mL
D3gmLmol/L

Mode No.
Pre Int
Del KDel SensInt TimeInt Sens
Brt Speed
Pulse

409033240

Mode No.
Pre Int
Del K
Del Sens
Int Time
Int Sens
Brt Speed
Pulse

409033240sec
mV
sec
mV

Non

Measurement of sample
Cndt No.
MethodBuret No.
Amp No.
D. Unit
S-Timer
C.P. mLT Timer
D.P. mLEnd Sens
Over mL
Max.Vol.

2
Auto
1
1pH
1027
1001000
0.360

sec
mL
sec
mL
mL
mL

ConstantNo.
SizeBlank
Molarity
FactorKL

22.041250.196
0.5
1.005
42.02
0Unit
FormulaDigits
Auto In Pram.

%(B-D)*K*F*M/(S*10)
4Nong
mL
mol/LsecmV
secmV

Measurement results
Number ofMeasurements

Size(g)Titrant
Volume (mL)NCO content(%)

Statistical calculation
results

Blank

1
2―
―

50.17850.214――

Avg.
(Blank)50.196 mL

Sample1232.04122.04292.047332.10532.03532.01718.71418.77118.749Avg.
SDCV

18.74 %
0.0287 %0.15 %

Measurement of blank

Measurement of sample

Examples of measurement curves

5. Note(1) Dehydrated toluene (less than 50 ppm water content) is used as a solvent to dissolve sample. Please notethat the water in solvent causes measurement error because it reacts with isocyanate group.
(2) Electrode which can be directly inserted into Erlenmeyer flask is preferred for this titration.

Keywords：Isocyanates, NCO, Neutralization titration, JIS K 6806, JIS K 1603, JIS K 7301

*Some measurement would not be possible depending on optional configuration of system.