Injection molding is the largest single application for polypropylene — and our deepest area of expertise. Whether you mold housewares, automotive interiors, appliance housings, or thin-wall food packaging, the right PP resin makes the difference between a profitable cycle and a problem line. We supply both homopolymer and impact copolymer injection grades, matched precisely to your process and end-use.
Across the wide range of injection-molded parts, a few resin attributes consistently determine part quality, cycle time, and scrap rate. Here's what we look for when matching a grade to your mold.
MFR must match part geometry and wall thickness — too low and the cavity won't fill; too high and mechanical properties suffer.
Homopolymer for maximum rigidity; impact copolymer where drop resistance and toughness matter. The wrong choice causes field failures.
Consistent shrinkage and low warpage — controlled by MWD and copolymer structure — keep parts in tolerance across production runs.
Consistent base resin color and additive package ensure reproducible coloring and gloss, batch after batch.
Stable MFR and density from lot to lot prevent processing drift — the foundation of low scrap rates and high uptime.
Three grades cover the vast majority of injection molding applications — from rigid housewares to thin-wall food packaging. Click any grade for full TDS specifications.
| Grade | Type | MFR (g/10min) | Best For | Manufacturer |
|---|---|---|---|---|
| HP550J → | Homopolymer | ~3.5 | Housewares, toys, thin-wall parts, general rigid molding | Leading Mill |
| EP300H → | Impact Copolymer | ~3-5 | Automotive interiors, appliances, large crates, luggage | Leading Mill |
| EP548R → | Impact Copolymer | ~25-30 | Thin-wall food packaging, disposables, closures | Leading Mill |
Not sure which fits? Tell us your part — we'll recommend the right grade.
From everyday housewares to precision thin-wall packaging — here's how our grades map to the parts you make.
Containers, cups, basins, kitchen utensils, and storage items. Stiffness, surface gloss, and easy coloring are key.
High stiffness and excellent surface finish at a competitive cost. The standard choice for everyday rigid housewares.
Returnable distribution crates, beverage trays, industrial totes, and waste bins. Drop resistance and stack strength under load.
High impact resistance and rigidity-toughness balance for large, load-bearing parts that must survive repeated handling.
For lighter-duty crates where maximum stiffness and cost efficiency outweigh extreme impact needs.
Door trims, instrument panels, washing machine tubs, refrigerator liners, and vacuum cleaner bodies. Impact, heat, and dimensional stability.
Outstanding low-temperature impact and rigidity-toughness balance. Tuned for large, load-bearing parts that face in-service impact and thermal cycling.
Food containers, deli tubs, takeaway boxes, disposable tableware, and closures. High flow for thin walls and fast cycles, with food-contact compliance.
High flow fills thin-wall cavities fast while the impact copolymer structure preserves drop resistance. Food-contact compliant.
For thin-wall parts where stiffness is the priority and impact resistance is secondary.
PP processes easily on standard injection molding equipment. Use these ranges as a starting point; fine-tune to your specific mold geometry and cycle.
| Parameter | HP550J | EP300H | EP548R |
|---|---|---|---|
| Melt Temperature | 180 – 220 °C | 190 – 230 °C | 200 – 230 °C |
| Mold Temperature | 20 – 50 °C | 30 – 60 °C | 20 – 50 °C |
| Injection Pressure | 60 – 100 MPa | 70 – 110 MPa | 80 – 120 MPa |
| Screw Speed | 40 – 80 rpm | 40 – 70 rpm | 80 – 150 rpm |
Describe your part, your mold, and your cycle. Within 24 hours we'll recommend the best PP grade — with mill-direct pricing and current availability.