Overview
ISO 6744-3:1999 - Binders for paints and varnishes - Alkyd resins - Part 3: Determination of unsaponifiable matter content - specifies a laboratory method to measure the unsaponifiable matter in alkyd resins. The procedure is performed after the saponification step described in ISO 6744-2 and is not applicable to modified alkyd resins (see ISO 6744‑1:1999). This standard is intended for quality control and compositional analysis of binders used in paints and varnishes.
Key topics and technical requirements
- Scope and linkage: Always used in conjunction with ISO 6744‑2 (first step: saponification and filtration). References include ISO 6744‑1, ISO 6744‑4, ISO 3696 and sampling guidance (ISO 15528).
- Principle: Dry the filtrate from ISO 6744‑2, extract non‑saponifiable components with an organic solvent, evaporate solvent, dry and weigh the residue. Calculate percentage of unsaponifiables relative to the initial sample mass.
- Extraction methods: Two validated options:
- Diethyl ether method (with hydroquinone added to ether to inhibit peroxides).
- Light petroleum (petroleum ether 30/50) method - recommended where ether emulsions are problematic.
- Reagents: Analytical grade solvents (diethyl ether, light petroleum 30/50), ethanol (95 % v/v), acetone, KOH solution (56 g/L), laboratory water (ISO 3696 quality 3).
- Apparatus: Standard lab glassware including 250 mL separatory (decanting) funnels, rotary evaporator or water bath for solvent removal, and drying oven at ~105 °C.
- Operational details:
- Perform determinations in duplicate.
- If emulsions form with ether, additives such as ethanol, saturated NaCl or a few drops of dilute mineral acid may be used to break them.
- Dry residue to constant mass: consecutive weighings must not differ by more than 0.1% (of the lower value); weigh to 1 mg accuracy.
- Calculation: Unsaponifiable content w (%) = (mass of dried residue / mass of test portion) × 100, where the test portion mass is as defined in ISO 6744‑2.
Applications and users
- Who uses it: Paint and varnish manufacturers, raw material suppliers, quality control laboratories, and R&D teams analyzing alkyd binder composition.
- Practical uses:
- Quality control of alkyd resin batches.
- Verification of raw material purity and consistency.
- Supporting product specifications and regulatory documentation.
- Troubleshooting formulation and performance issues related to non‑saponifiable fractions.
Related standards
Keywords: ISO 6744-3:1999, alkyd resins, unsaponifiable matter content, binders for paints and varnishes, extraction method, diethyl ether, petroleum ether, laboratory analysis.
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