What Are Black PP Granules? Technical Guide from Production to Injection

How are black PP granules produced?

Production consists of four stages:

1. Sorting & Grinding: Recycled PP is sorted, contaminants are removed and the material is ground to a homogeneous size.
2. Washing & Drying: Dirt, labels and metallic residues are removed through washing lines; moisture is extracted.
3. Extrusion & Filtration: Molten polymer is purified through 120-mesh filtration; carbon black masterbatch is added at this stage.
4. Pelletizing & QC: The molten strand is cooled and cut into pellets; every batch is tested for MFI, density and ash content.

What do the technical values mean?

• MFI (Melt Flow Index): Indicates how fluidly the granule flows in the mold. 12–17 g/10min is ideal for crates and thin-walled parts; 5–12 is sufficient for thick-walled parts.
• Density: 0.90–0.93 g/cm³ indicates material close to pure PP; density rises as filler content increases.
• Ash content: The percentage of non-combustible residue. ≤ 0.5% means clean, injection-friendly granule; high ash clogs nozzles.
• Filtration (mesh): 120-mesh filtration traps particles that would clog machine nozzles and mold channels.
• Carbon black: A 2–2.5% ratio provides deep, homogeneous black colour and UV resistance.

Where is it used?

The most common application is fruit & vegetable crates — most black crates produced in Turkey are molded from recycled black PP granules. It is also used for industrial pallets, waste bins, pots, automotive interior parts, pipes and profiles.

Recycled black PP or virgin PP?

For products like crates and pallets where durability matters more than appearance, recycled black granules offer a 30–50% cost advantage over virgin material while providing more than adequate mechanical performance for these applications.