2-Hydroxypropyl Acrylate (2-HPA, CAS No. 25584-83-2) is a functional acrylic monomer produced by the addition reaction of acrylic acid with propylene oxide. Commercial 2-HPA is a clear, colorless liquid comprising a major isomer (2-hydroxypropyl acrylate, ~75–80%) containing a secondary hydroxyl group, and a minor isomer (1-methyl-2-hydroxyethyl acrylate, ~20–25%) containing a primary hydroxyl group.
With a molecular formula of C6H10O3 (molecular weight 130.14 g/mol), 2-HPA combines a low homopolymer glass transition temperature (Tg ≈ -7°C) with low volatility, excellent flexibility, and moderate crosslinking reactivity.
Key Physical and Chemical Characteristics
| Technical Parameter | Standard Specification | Significance |
|---|---|---|
| CAS Registry Number | 25584-83-2 | Global regulatory compliance |
| Assay (Total Isomers by GC) | ≥ 98.5% (typical 99.0%) | High polymerization efficiency |
| Molecular Weight | 130.14 g/mol | Low VOC formulation profile |
| Appearance | Clear, colorless liquid | Ensures high-clarity coatings |
| Homopolymer Tg | -7°C | Balanced flexibility and toughness |
| Moisture Content (KF) | ≤ 0.10 wt% | Prevents isocyanate consumption |
| Acid Value (as Acrylic Acid) | ≤ 0.50 wt% | Prevents catalyst poisoning |
| MEHQ Inhibitor | 200–400 ppm | Ensures storage stability |
Major Industrial Applications of 2-HPA
1. Automotive OEM & Coil Coatings
In automotive topcoats and industrial coil coatings, 2-HPA provides the optimal combination of flexibility, impact resistance, and weatherability. The branched methyl group on the propyl chain disrupts polymer crystallization, enhancing film clarity and flexibility even after thermal aging.
2. UV/EB Curable Formulations
2-HPA acts as an efficient monofunctional reactive diluent in radiation-cured wood finishes, plastic coatings, and screen-printing inks. It exhibits significantly lower skin irritation and lower volatility compared to lower-molecular-weight acrylates, offering a safer working environment.
3. Specialty Acrylic Adhesives and Sealants
When copolymerized into pressure-sensitive adhesives (PSAs), 2-HPA improves polymer cohesion and substrate wet-out on hydrophobic plastic substrates (such as polyethylene and polypropylene films) while maintaining high tack.
4. Synthetic Leather & Resin Modification
In polyurethane dispersions (PUDs) and acrylic leather coatings, 2-HPA enhances tensile elongation, bending fatigue resistance, and soft tactile feel.
Storage, Handling, and Procurement at DECHEM
DECHEM ensures steady supply and strict batch-to-batch consistency of 2-HPA. Product is packaged in standard 200 kg steel drums, 1,000 kg IBC totes, or bulk ISO tanks under dry nitrogen blankets with dissolved oxygen monitoring.
- Storage Temp: store between 15°C and 25°C away from direct sunlight, open flames, and oxidizing agents.
- Shelf Life: 12 months under recommended warehouse conditions with proper container seal.