What Is Hydroxypropyl Acrylate (HPA) and How Is It Used in Polymer Applications?
Technical Introduction
Hydroxypropyl Acrylate (HPA) is a clear, colorless to pale yellow liquid monomer characterized by the presence of both acrylate and hydroxyl functional groups. The acrylate group enables rapid polymerization, while the hydroxyl group provides sites for further chemical modification, crosslinking, or adhesion promotion. HPA is widely used as a reactive diluent or co-monomer in the production of coatings, adhesives, sealants, and specialty polymers. Its unique dual functionality allows for enhanced flexibility, hydrophilicity, and improved mechanical properties in polymer formulations.
Applications
UV-Curable Coatings: Improves flexibility and adhesion in coatings for wood, plastic, and metal surfaces.
Adhesives and Sealants: Enhances bonding strength and water resistance.
Acrylic Resins: Used as a co-monomer to modify hardness, toughness, and chemical resistance.
3D Printing: Serves as a reactive monomer for photopolymer resins.
Textile Finishing: Provides hydrophilic properties and improves fabric handle.
Dental Materials: Used in resin-based composites for restorative dentistry.
Advantages
Dual Functionality: Combines polymerizable acrylate with reactive hydroxyl groups.
Improved Flexibility: Enhances toughness and reduces brittleness in polymers.
Good Adhesion: Hydroxyl groups improve bonding to various substrates.
Fast Polymerization: Acrylate group allows rapid curing under UV or thermal conditions.
Versatile Compatibility: Compatible with various monomers and polymerization systems.
Specifications (Typical Parameters)
| Parameter | Description | Typical Value |
|---|---|---|
| Appearance | Physical state | Clear to pale yellow liquid |
| Purity | Content of HPA | ≥ 99% |
| Hydroxyl Value | Amount of hydroxyl groups | 250 - 260 mg KOH/g |
| Acid Value | Free acid content | ≤ 0.05 mg KOH/g |
| Viscosity (25°C) | Flow property | 15 - 30 mPa·s |
| Refractive Index | Optical property | 1.435 - 1.445 |
| Density (25°C) | Mass per volume | 1.05 - 1.07 g/cm³ |
FAQ
Q1: What polymerization methods are used with HPA?
A: HPA polymerizes via free radical mechanisms under UV or thermal initiation, often in copolymer systems.
Q2: Can HPA improve adhesion in coatings?
A: Yes, the hydroxyl groups provide sites for hydrogen bonding and crosslinking, enhancing adhesion.
Q3: Is HPA suitable for flexible coatings?
A: Yes, it improves flexibility and reduces brittleness compared to pure acrylate polymers.
Q4: What safety precautions are needed when handling HPA?
A: Use protective gloves and goggles; ensure good ventilation to avoid inhalation of vapors.
Q5: Can HPA be used in waterborne systems?
A: It is generally used in solvent or reactive diluent systems, but can be modified for waterborne formulations.
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