Automotive SMC UPR
Key Features
- Precise MgO thickening profile for 3-5 day SMC maturation
- Class A surface with PVAc or PMMA LPA
- Automotive OEM specifications compliant
- Low contamination — no paint adhesion failure species
- Consistent molecular weight for predictable SMC rheology
Automotive SMC UPR is a precisely engineered orthophthalic/isophthalic unsaturated polyester resin formulated for Class A automotive SMC body panel production. It delivers a tight thickening profile with MgO that achieves the maturation viscosity required for SMC processing within 3-5 days, combined with Class A surface capability when used with PVAc or PMMA LPA systems.
The resin is characterized by a high acid value (22-32 mg KOH/g) for controlled MgO thickening, precise molecular weight distribution for consistent SMC rheology, and is free from contaminating species that could cause paint adhesion failures. The styrene content is maintained at 30-35% for acceptable OEL compliance in closed SMC press operations.
Cure is by DCP (dicumyl peroxide) or TBPB at 145-165°C press temperature, 20-60 second cure cycle per mm of part thickness. Cured surface hardness (Barcol 35-45) and low waviness index (dI/dA <0.5 per D65/10° geometry) meet automotive OEM specifications for exterior body panels. The resin is compatible with all standard automotive SMC glass fiber systems (PPG, Owens Corning, Jushi), LPA grades, and mineral filler systems.
Specifications
| Parameter | Value |
|---|---|
| Acid Value | 22-32 mg KOH/g |
| Appearance | Clear to pale yellow liquid |
| Cure System | DCP / TBPB (145-165°C) |
| Styrene Content | 30-35% |
| Viscosity (25°C) | 700-1200 mPa·s |
| Barcol Hardness (cured) | 35-45 |
| Thickening Target (3-5 days) | 8,000-15,000 mPa·s×10³ |
Applications
FAQ
PMMA LPA (lpa-pmma) at 10-20 phr provides the best surface for critical Class A panels (hood, roof, trunk) due to its excellent surface smoothing and low waviness index. PVAc LPA (lpa-pvac) at 8-15 phr is used for semi-structural and interior-facing panels where a good but not Class A surface is acceptable. Polystyrene LPA (lpa-polystyrene) is used for structural BMC where surface appearance is less critical.
Direct Contact
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