Name: 1,4-Butanediol (BDO)
Brand: Coatingsink
SKU: 1-4-butanediol-bdo
Availability: InStock

Question 1

What distinguishes 1,4-butanediol from other short-chain diols in polyurethane chain extension?

Accepted Answer

BDO is the dominant hard-segment chain extender for thermoplastic polyurethanes (TPU) because the four-carbon even-numbered chain enables close packing and hydrogen bonding between urethane groups, generating well-ordered hard-domain microstructure. This phase separation gives TPU coatings and cast films high tear strength, good abrasion resistance, and rubber elasticity at low temperatures. Compared to ethylene glycol, BDO gives softer, more flexible hard segments with lower processing temperature; compared to HDO, BDO produces higher hard-segment crystallinity and a higher heat deflection temperature.

Question 2

How is BDO used in polyester resin synthesis for powder coatings?

Accepted Answer

In saturated polyester resins for TGIC or HAA-cured powder coatings, BDO is used as a branching diol or chain modifier at 5–15 mol% of the diol component. Its four-carbon chain reduces Tg by 8–12°C versus isophthalic acid/neopentyl glycol systems, improving melt flow and leveling during powder stoving at 180–200°C. Polyesters incorporating BDO show better flexibility and impact resistance in cured films, making them preferred in coil-coating primer formulations where forming operations require good T-bend flexibility. BDO also accelerates esterification vs. neopentyl glycol due to lower steric hindrance.

Question 3

What purity specifications are critical for coatings-grade BDO?

Accepted Answer

Coatings-grade BDO requires ≥99.5% purity with tight impurity control: γ-butyrolactone (GBL) ≤200 ppm, tetrahydrofuran (THF) ≤50 ppm, and water ≤500 ppm. GBL acts as a chain terminator in isocyanate reactions, reducing molecular weight build-up and causing soft or tacky films. THF contamination is a process indicator and a VOC concern. Color (APHA ≤10) and acidity (≤0.02% as acetic acid) are standard QC parameters. Store in nitrogen-blanketed tanks to prevent moisture uptake and discoloration.

Purity	≥99.5%
Appearance	colorless viscous liquid
GBL Content	≤200 ppm
Color (APHA)	≤10
Boiling Point	230°C (760 mmHg)
Melting Point	20°C
Water Content	≤0.05%
Hydroxyl Value	~1244 mgKOH/g
Density (25°C)	1.017 g/cm³
Molecular Weight	90.12 g/mol
Viscosity (25°C)	70–90 mPa·s

1,4-Butanediol (BDO)

Specifications

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