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D2635-07 – Standard Test Method Technical Guide
The ASTM D2635-07 (Reapproved 2012) specification defines the quality and purity requirements for Methyl Isobutyl Carbinol (MIBC, also known as 4-methyl-pentanol-2). This standard is essential for formulators and quality assurance teams in the paint, varnish, lacquer, and related coatings industries who rely on this high-boiling solvent for consistent performance.
📐 Scope and Referenced Documents
This specification covers the material property limits for MIBC. Conformance to these limits must be determined by applying the rounding-off method of Practice E29, and all values are expressed in SI units. For specific hazard information, users are directed to the supplier’s Material Safety Data Sheet (SDS). The standard references critical ASTM methods, including Guide D268 (Sampling & Testing), Test Method D1209 / D5386 (Color), D1364 (Water), D1613 (Acidity), D1353 (Nonvolatile Matter), and D3329 (Purity by Gas Chromatography).
⚠️ Rounding Compliance: When determining conformance, Practice E29 requires that results be rounded “to the nearest unit” of the last right-hand digit of the specification limit. This standardizes the pass/fail evaluation of test data against the specification limits.
📊 Physical and Chemical Specifications
Methyl isobutyl carbinol must meet the following stringent requirements to ensure its suitability as a solvent in high-performance coatings. The apparent specific gravity is temperature-dependent; the test temperature must be specified and match the acceptance criterion.
| 🟦 Property | 📏 Specification | ⚡ Test Method |
|---|---|---|
| Apparent Specific Gravity (20/20°C) | 0.806 – 0.809 | D268 / D4052 |
| Apparent Specific Gravity (25/25°C) | 0.803 – 0.806 | D268 / D4052 |
| Color, Pt-Co units, max | 10 | D1209 |
| Water, wt%, max | 0.1 | D1364 |
| Acidity (as Acetic Acid), wt%, max | 0.005 | D1613 |
| Nonvolatile Matter, mg/100 mL, max | 5 | D1353 |
| Purity, wt%, min | 98.0 | D3329 |
💡 Instrumental Color Analysis: While Test Method D1209 is the primary method for Pt-Co color, the instrumental method D5386 (Tristimulus Colorimetry) has been shown to be statistically equivalent for many solvents. The standard notes that methyl isobutyl carbinol was not explicitly included in the interlaboratory equivalence study for this alternative method.
🧪 Test Methods and Sampling
Accurate testing begins with representative sampling in accordance with Practice E300. The apparent specific gravity must be measured to the third decimal place. Water content is determined using the Karl Fischer reagent titration method (D1364) to ensure it does not exceed 0.1 wt%. The low acidity limit is enforced via Test Method D1613, while nonvolatile matter is established through D1353. The purity is rigorously verified by gas chromatography per Test Method D3329.
❓ Frequently Asked Questions
🔍 What is the minimum purity for methyl isobutyl carbinol?
D2635 specifies a minimum purity of 98.0 percent by weight, determined by gas chromatography in accordance with Test Method D3329.
💡 How does the standard address acidity?
Acidity is limited to a maximum of 0.005 wt% (calculated as free acetic acid). This stringent limit, tested via D1613, is critical for preventing unwanted side reactions in sensitive coating and chemical formulations.
⚡ Why are two specific gravity ranges provided?
The specification provides ranges for both 20/20°C (0.806 – 0.809) and 25/25°C (0.803 – 0.806) to accommodate different laboratory standard temperatures. The chosen temperature reference must match the test methodology used.
📌 What is the nonvolatile matter requirement?
The nonvolatile matter must not exceed 5 mg per 100 mL. This low residue requirement ensures the solvent will not leave undesirable deposits upon evaporation, maintaining film integrity in coating applications.