Low Styrene UPR (<35% Styrene)
Key Features
- Styrene content below 35% wt for OEL compliance
- Comparable reactivity to standard grades
- Drop-in replacement requiring no process changes
- Reduced workplace air monitoring burden
- Compatible with standard MEKP/cobalt cure systems
Low Styrene UPR is a specially formulated unsaturated polyester resin containing less than 35% styrene monomer by weight, designed to comply with increasingly strict occupational exposure limits (OEL) for styrene in Europe, North America, and other regulated markets. The formulation achieves reduced styrene content while maintaining the viscosity (350-550 mPa·s) and reactivity needed for standard open-mold processes.
The resin uses a higher-molecular-weight polyester base with optimized maleate/fumarate ratio to deliver comparable mechanical properties to standard grades despite the lower styrene content. Flexural strength of cured laminates is 100-115 MPa with a modulus of 3.5-4.0 GPa. Gel time at 25°C with 1.5% MEKP is 15-25 minutes, preserving normal shop-floor processing windows.
This resin is recommended for fabricators seeking to reduce workplace styrene emissions without switching to styrene-free systems, providing a practical compliance pathway while retaining familiar processing characteristics. Suitable for hand lay-up, spray-up, and contact molding of industrial enclosures, transportation panels, and construction FRP.
Specifications
| Parameter | Value |
|---|---|
| Acid Value | 14-22 mg KOH/g |
| Appearance | Clear to pale yellow liquid |
| Density (25°C) | 1.13-1.15 g/cm³ |
| Styrene Content | <35% |
| Viscosity (25°C) | 350-550 mPa·s |
| Flexural Strength (cured) | 100-115 MPa |
| Gel Time (25°C, 1.5% MEKP) | 15-25 min |
Applications
FAQ
In the EU (REACH regulation and SCOEL), the short-term OEL for styrene is 100 ppm (8-hour TWA target 50 ppm). In the US, OSHA PEL is 100 ppm TWA and ACGIH TLV is 20 ppm. Low styrene resins (<35%) reduce source emissions significantly, though engineering controls (ventilation, enclosure) are still required for full compliance.
Direct Contact
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