PBT-Sabic Valox 357
To achieve ultimate dielectric isolation, high-heat flammability resistance, and superior impact toughness in electrical enclosures, SABIC's Valox 357 stands as the premier unreinforced PBT+PC alloy benchmark. Featuring a density of 1.34 g/cm³ and a non-blooming flame retardant package, this material delivers a V-0 flammability rating at 0.75mm and a 5VA rating at 2.5mm. Jucheng Precision, operating under IATF 16949 and ISO 13485 frameworks, specializes in molding Valox 357. Backed by 35+ advanced injection presses and 5-axis CNC-machined H13 tooling, we control its complex alloy shrinkage (0.8%-1.4%) to eliminate weld-line weakness, delivering high-gloss, pristine electrical components verified by Zeiss CMM.
SABIC Valox 357 PBT+PC Alloy Performance & Safety Profile
VALOX™ Resin 357 is an unreinforced, impact-modified, brominated flame-retardant PBT+PC blend engineered by SABIC, certified to deliver maximum chemical resistance and exceptional dielectric strength under UL 94 safety ratings:
| Flammability & Performance Standard | VALOX 357 Nominal Spec Value | Molding & End-Use Advantage |
|---|---|---|
| UL 94 V-0 Rating | V-0 Rated at 0.75 mm Thickness | Provides self-extinguishing safety in thin-walled housings, preventing dynamic heat buildup and flame propagation in electrical terminal blocks. |
| UL 94 5VA Rating | 5VA Rated at 2.5 mm Thickness | Resists heavy open bar flames without structural burn-through. Essential for high-voltage power distribution boxes. |
| High Impact Toughness | ASTM Notched Izod Impact 350 J/m | PBT base copolymer blended with elastomer-modified PC provides exceptional drop-test and impact resilience compared to standard rigid PBT. |
Process Compatibility and Mold Configuration for Valox 357
With its high viscosity and PC-blend chemistry, Valox 357 requires optimized flow designs to prevent mechanical stress:
| Molding Process | Molding Compatibility & Execution Details |
|---|---|
| Electrical Switches & Enclosures | Excellent. Fully optimized for high-voltage smart meter housings, heavy-duty industrial relays, switches, and consumer electronic casings. |
| Coil Bobbins & Bobbin Windings | Excellent. Its low moisture absorption and excellent flow-thickness ratio prevent structural distortion under high copper wire tension. |
| Low-Temperature Industrial Seals | Good. Retains a notched Izod impact of 110 J/m even at subzero temperatures (-30°C), preventing brittle cracking in outdoor components. |
PBT-SABIC Valox 357 Alloy Processing & Mold Design Guide
As a PBT+PC blend, Valox 357 combines semi-crystalline PBT with amorphous PC. Managing chemical outgassing and complex shrink factors is vital during molding:
S136 Anti-Acidic Mold Cavities
At high melt temperatures, brominated flame retardants in Valox 357 can degrade slightly and release acidic outgassing that corrodes tool steel. Jucheng’s tooling division prevents cavity pitting by using premium S136 stainless steel hardened to 48–52 HRC, combined with deep venting channels (0.015mm) on parting lines.
Weld-Line Prevention & Gates
Cold weld lines (knit lines) severely compromise the structural integrity and local UL 94 V-0 fire barriers. We design generous gates (minimum 60% of part wall thickness) and implement sequential hot-runner valve gates to shift weld lines away from load-bearing or active zones.
Scientific Pre-Drying Protocol
PBT and PC are both highly sensitive to moisture at high melt temperatures. Wet molding results in rapid hydrolytic chain cleavage, causing severe splay, gas bubbles, and a major drop in impact strength. We desiccant dry Valox 357 resin at 120°C (248°F) for 3–4 hours, keeping moisture below 0.02%.
Complex Alloy Shrinkage Management
The crystalline PBT phase shrinks faster than the amorphous PC phase, resulting in anisotropic shrink ranges (0.80% to 1.40%). We utilize 5-axis CNC machines to cut precise mold cavities and balance cooling paths, ensuring zero warping and zero dimension defects on Zeiss CMM verification.
Key Application Fields for PBT-Sabic Valox 357
- Smart-Grids & Electrical Systems: High-voltage circuit breakers, smart electricity meters, terminal blocks, electrical relay housings, wall switch frames, and coil bobbins.
- EV Charging & Automotive (IATF 16949): Electric vehicle charging gun housings, high-voltage junction box covers, interior fuse housings, and vehicle sensor housings.
- Medical Diagnostics & Instruments (ISO 13485): Non-sterile surgical instrument housings, diagnostic device casings, analytical laboratory trays, and hospital power terminals.
Properties
| Density | 1.34 g/cm³ |
| Melt Mass-Flow Rate (MFR) (250°C/2.16kg) | 12 g/10 min |
| Tensile Modulus | 2,100 MPa |
| Tensile Stress at Yield | 50 MPa |
| Tensile Stress at Break | 40 MPa |
| Tensile Elongation at Break | 30 % |
| Flexural Modulus | 2,100 MPa |
| Flexural Strength | 80 MPa |
| Izod Notched Impact Strength (23°C) | 350 J/m |
| Izod Notched Impact Strength (-30°C) | 110 J/m |
| Melting Temperature | 223 °C |
| Vicat Softening Point | 137 °C |
| Heat Deflection Temperature (HDT @ 1.82 MPa) | 98 °C |
| Linear Mold Shrinkage (Flow Direction) | 0.80 - 1.10 % |
| Linear Mold Shrinkage (Transverse Direction) | 0.90 - 1.30 % |
| Flammability Rating (0.75mm) | UL 94 V-0 Class |
| Flammability Rating (2.5mm) | UL 94 5VA Class |
| Maximum Part Size | 1000 x 800 mm |
| Minimum Part Size | 1 x 1 mm |