SMC/BMC Grade UPR
Key Features
- High acid value for effective MgO/Mg(OH)2 thickening
- Controlled maturation profile for consistent SMC handling
- Compatible with DCP/TBPB hot-press cure systems
- Class A surface capability with LPA
- Meets automotive OEM SMC/BMC specifications
SMC/BMC Grade UPR is specially formulated for sheet molding compound (SMC) and bulk molding compound (BMC) production, where the resin must undergo controlled thickening via reaction with magnesium oxide (MgO) or magnesium hydroxide thickeners to achieve a handleable, tack-free compound within 24-72 hours of preparation.
The resin is characterized by high acid value (20-35 mg KOH/g) to ensure efficient ionic thickening with MgO at 1-3 phr loading, targeting a final compound viscosity of 10-100 million mPa·s. Styrene content is 30-35% for good fiber wet-out during compounding. Cure is initiated by dicumyl peroxide (DCP) or TBPB at compression molding temperatures of 140-165°C.
Cured SMC/BMC panels deliver flexural strength of 150-200 MPa (at 25-30% glass content), excellent surface quality with low porosity, and Class A surface capability when used with LPA (low profile additive). The resin meets automotive OEM specifications for exterior body panels and structural compression molded parts, and is compatible with all commercial SMC glass fiber chopped strand mats and continuous rovings.
Specifications
| Parameter | Value |
|---|---|
| Thickener | MgO 1-3 phr |
| Acid Value | 20-35 mg KOH/g |
| Appearance | Clear to pale yellow liquid |
| Cure Initiator | DCP / TBPB |
| Styrene Content | 30-35% |
| Mold Temperature | 140-165°C |
| Viscosity (25°C) | 600-1200 mPa·s |
Applications
FAQ
Magnesium oxide (or hydroxide) reacts with the carboxylic acid groups in the UPR polymer chain through an ionic coordination mechanism, forming Mg-carboxylate salts that create a three-dimensional network. This raises viscosity from ~1,000 mPa·s to >10,000,000 mPa·s over 24-72 hours at ambient temperature. The 'maturation window' (the period of optimal compound viscosity for pressing) is typically 3-10 days. Viscosity is controlled by MgO particle size, loading level, and resin acid value.
Direct Contact
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