Reconciling solvent and concentration in PVB grade viscosity data

Trial design and interpretation

Record solvent composition, concentration, temperature and instrument beside each reading. Request a common-method retest when conditions differ. Once solution flow is understood, verify adhesion on the target substrate.

Recording Solution viscosity

Solution viscosity (mPa·s): Kuraray Mowital B 30 H published example 35–60. Measure a 10% ethanol solution at 20 °C using the Höppler method. Residual PVOH (% by mass): Kuraray B 30 H: 18.0–21.0. Compare mass percentages. Keep mol % on a separate basis.

Why does one PVB grade have two viscosity ranges?

Check solvent and instrument. Compare falling-ball results in ethanol separately from rotational measurements in ethanol/toluene. Ink binders: Prepare samples in the actual solvent blend. At equal resin concentration, compare viscosity, clarity and print adhesion.

What to record

• Solvent ratio
• Test concentration
• Temperature and method
• Adhesion to substrate

Technical references

• Kuraray: Mowital B 30 H specification and methods ↗

Products and processes