Recycled HDPE Price per Ton 2026: Flake, Pellet and Colour Effect

High-density polyethylene is a semi-crystalline thermoplastic with a density range of 0.940–0.970 g/cm³ when tested in accordance with ISO 1183-1:2019, a number-average molecular weight generally between 20,000 g/mol and 200,000 g/mol, and a melt flow index that remains below 1.0 g/10 min at 190 °C under 2.16 kg for blow moulding and pipe grades when measured to ISO 1133-1:2022. Recycled HDPE in the 2026 market is sold principally as hot-washed flake, cold-washed flake, or melt-filtered pellet. The price per tonne for each form is not a single commodity index; it is a function of residual contamination, melt flow consistency, density, colour coordinates, and the degree of stabiliser re-formulation. Spot and contract price discovery for 2026 remains provisional in many regions because annual recycled polymer contracts are frequently indexed to virgin HDPE market movements or ethylene contract data rather than fixed on 1 January. Published fixed-price 2026 assessments for specific flake and pellet grades are therefore limited; the available figures are forward curves, formula-based settlements, or price indications from Q4 2025 negotiations.

Which Process Variables Separate Post-Consumer Flake from Regranulated Pellet Pricing in 2026?

Flake pricing reflects the cost of collection, sorting, size reduction, washing, density separation, and drying. A typical European hot-wash line for mixed rigid HDPE operates with a granulator screen of 12–16 mm, a hot friction washer reaching 80–90 °C, a float-sink tank set to 1.0–1.1 g/cm³ specific gravity, and a mechanical dryer reducing moisture to below 1.0 wt% before bagging. The flake product retains a bulk density of 0.40–0.55 g/cm³, which raises shipping and silo storage cost per tonne relative to pellet. Pellet pricing adds the extrusion step: a co-rotating twin-screw extruder with an L/D 40:1 screw, vacuum degassing, a screen changer using 150–200 µm mesh, and a strand die. This step removes residual fines and non-melting contaminants, reduces volatiles to below 0.1 wt%, and increases bulk density to 0.55–0.65 g/cm³. The flake-to-pellet mass yield in a well-controlled post-consumer HDPE line is typically 92–97%; the lower bound is reached when printed film layers and label adhesives raise melt filtration back-pressure and require screen-pack changeover.

Price per tonne for 2026 flake and pellet is also tied to lot-to-lot melt flow stability. A natural blow moulding flake classified as 0.3–0.5 g/10 min can be blended into virgin HDPE without re-compounding, whereas a mixed-colour flake with a melt flow range of 0.2–0.8 g/10 min requires homogenisation. Pellet lines that install a melt pump and on-line capillary rheometer can ship pellets with a melt flow variation of ±0.05 g/10 min, which supports a price premium. In contrast, flake sold without melt-flow homogenisation carries a discount because downstream extrusion or injection moulding must compensate for screw torque variation.

Colour is a hard price modifier for recycled HDPE in 2026 because it determines not only aesthetic application but also the survival of the polymer chain during repeated processing. Natural flake from dairy bottles and clear rigid packaging retains the largest addressable market, including white or pastel blow moulded containers. Mixed-colour flake is downgauged into dark-grey or black injection moulding compounds. The colourimetric boundary is normally defined as a CIELAB ΔE against a reference standard of ≤2.5 for natural grades and ≤1.0 for white grades measured under D65/10° conditions per ISO 11664-4:2008. When recycled HDPE flake is sorted by near-infrared systems, carbon black absorbs rather than reflects the NIR signal and black parts may be lost to the residue stream; this reduces sorting yield and increases the cost per tonne of recovered natural flake.

Rheological and Mechanical Consequences of Pigmented Recyclate in HDPE Moulding Grades

Pigmented HDPE recyclate is not inert in the melt. Chromium- or iron-containing pigments, certain organic reds, and residual label inks can accelerate thermo-oxidative chain scission under repeated extrusion. The mechanism is radical generation at melt temperatures above 220 °C, with a measurable drop in oxidation induction time when evaluated by ISO 11357-6:2018. A natural post-consumer HDPE pellet may exhibit an oxidation induction time above 20 min at 200 °C; a dark-brown or black mixed-colour pellet may fall below 10 min unless additional hindered phenol-phosphite stabiliser is introduced at 0.15–0.25 wt%. The compounding consequence is visible in tensile yield stress retention. Injection-moulded specimens from natural pellet can retain tensile yield stress above 23 MPa when tested per ASTM D638-14 at 50 mm/min, while mixed-colour pellet may fall to 19–21 MPa depending on contaminant content. Published data for this specific configuration is limited because post-consumer feedstocks vary by collection scheme, but the direction of the effect is consistent with peer-reviewed degradation studies.

Melt filtration is the primary unit operation that compensates for pigmented contamination. A screen changer fitted with 250 µm screens protects a sheet extrusion die, while a 120–150 µm screen pack is required for thin-wall injection moulding of dark mixed-colour HDPE. The trade-off is head pressure. Fines and gel-like crosslinked polyethylene particles accumulate on the screen, raising melt pressure from 120 bar to 220 bar within 4–8 h of continuous operation. At that point the line must switch to a fresh screen, interrupting throughput. This operational cost is embedded in the pellet price rather than the flake price.

In direct flake-to-sheet extrusion, a single-screw extruder with a 30:1 L/D screw and a crammer feeder is necessary because flake bulk density is low and the feed throat can bridge. Barrel zones are set to 180–220 °C; melt temperature measured at the adapter should not exceed 230 °C for recycled HDPE containing residual paper labels, because cellulose char can form black specks above that threshold. The use of pelletised mixed-colour HDPE eliminates the bridging limit but introduces higher melt viscosity if the pellet contains calcium carbonate filler from bottle caps; this raises melt pressure at the die. A gear pump is recommended when pressure fluctuation exceeds ±5% of setpoint.

If Carbon Black-Filled Recycled HDPE Is Processed Below 200°C, What Limits Mechanical Performance?

This condition is relevant to black injection moulding compound. At barrel temperatures below 200 °C, the viscosity of HDPE remains high, and mould filling of thin-wall parts becomes pressure-limited. Carbon black raises melt viscosity further through filler networking. Injection moulding of black mixed-colour pellet at 190–200 °C may require clamp force above 1,800 kN for a 500 g shot and packing pressure above 70 MPa. The mechanical risk is not only short shot but also frozen-in stress. Parts show lower environmental stress crack resistance when tested by ASTM D1693-15 because the combination of low melt temperature and high filler content reduces interlamellar tie molecules. The processing window narrows to ±5 °C in some high-speed moulds, below which gate freeze-off occurs prematurely. No published data specific to all mixed-colour 2026 feedstock exists; line trials on individual lots are needed because pigment loading is not uniform.

The purchase specification for recycled HDPE flake and pellet in 2026 should define melt flow rate per ISO 1133-1:2022, density per ISO 1183-1:2019, ash content per ISO 3451-1:2019, moisture per EN 12099:1997, and, for food-contact applications, migration testing under Regulation (EU) No 10/2011 or FDA 21 CFR 177.1520. Pigmented grades require a heavy metals screening under REACH Annex XVII and a colourimetric certificate per ISO 11664-4:2008. Without these clauses, a lower price per tonne for 2026 recycled HDPE flake may be negated by excess filtration consumables, off-spec colour correction, and loss of mechanical property retention in the final moulded or extruded part.