In LLDPE-based wood-plastic composite capstock and solid profile extrusion, 2–5 wt% of LyondellBasell POLYBATCH™ Birch 60171U/4 Concentrate Based in LLDPE is metered into a counter-rotating twin-screw compounding line producing high-density polyethylene/wood flour composite profiles. The concentrate is used where a birch-toned surface layer must be maintained across multiple manufacturing shifts, and the carrier resin is selected because its melt rheology matches the PE/wood flour matrix rather than the wood fraction. Gravimetric dosing is held to ±0.3 wt% because wood flour lot-to-lot chroma variation, particularly with ash levels between 0.8% and 2.2%, becomes visible in the extrudate when the colour concentrate drops below 3 wt%. Wood flour is pre-dried to ≤1.0% moisture content before side feeding, while the melt temperature at the die is kept between 155 °C and 180 °C to avoid thermal darkening of the wood fraction. The compounding line is typically a 28:1–36:1 L/D counter-rotating twin-screw extruder with vacuum venting at 0.06–0.09 MPa absolute to strip residual water and volatile wood extractives; die head pressure is maintained between 6 MPa and 14 MPa depending on profile wall stock. Calibration blocks and spray tanks are held at 15–25 °C to set surface gloss and prevent post-die colour drift. Regulatory documentation for the composite product references EN 15534-1:2014+A1:2017 for wood-plastic composites used in non-load-bearing applications and ASTM D7032-17 for decking and railing performance; the colourant addition is also screened against REACH Annex XVII restrictions on heavy metals and PAHs where the finished profile is placed on the EU market. Terminal product types include decking boards, railing sleeves, fascia profiles, and tongue-and-groove cladding.

How Does Pelletized LLDPE Carrier Pigment Distribute Across a 35-Mesh Rotational Molding Powder Bed?

Dry blending 1–2.5 wt% of the pelletized concentrate with 35-mesh polyethylene powder can be used in rotational molding only where a two-stage pre-compounding step or a high-intensity mixer has reduced the colour pellet below 600 µm; direct drum tumbling followed by mould charging is likely to produce localised tint streaks on interior surfaces of parts with wall thicknesses below 4 mm. Published data for this specific 60171U/4 pellet in rotomoulding applications is limited, so a pre-milled batch trial on a 200 kg powder line is required to establish minimum pre-blend residence time for the available ribbon blender or high-intensity mixer. The biaxial rotational molding cycle is run at oven set-point 265–315 °C and peak internal air temperature 175–210 °C, with a 3:1 or 4:1 rotation speed ratio on carousel machines; forced air cooling to 70 °C before water mist is applied reduces warpage and improves colour uniformity at sharp radii. Compliance documents for beige parts in public furniture and storage include EN 71-3:2019+A1:2021 heavy metal migration where children’s contact is foreseeable, ASTM D1998-21 for upright polyethylene tanks, and EU Regulation 10/2011 where the rotomoulded article is intended for repeated food contact as a container insert. Terminal products are outdoor sofas, coolers, planter liners, chemical dosing tanks, and equipment housings.

In high-cavitation closure molding, the beige concentrate in LLDPE carrier is dosed at 2–3.5 wt% into a 12–18 g/10 min melt index LLDPE or HDPE base resin using a gravimetric hopper loader on a 250–350 metric ton hydraulic toggle injection machine. The screw L/D is typically 20:1 to 24:1, plasticizing back pressure is set at 0.5–1.5 MPa hydraulic, and barrel zones are profiled from 190 °C in the feed zone to 220–240 °C at the nozzle; hold pressure between 35 MPa and 55 MPa keeps 0.8–1.2 mm-thick lid panels free of sink marks. Valve-gated hot runner tips are maintained at 1.5–2.5 mm diameter, and total melt residence time below 5 min prevents pigment degradation visible as colour shift at the gate vestige. Compliance requirements cited for closures include FDA 21 CFR 177.1520 for olefin polymers, EU Regulation 10/2011 with an overall migration limit of 10 mg/dm², and 21 CFR 178.3297 for colorants used in polymers; non-food closures are validated against REACH Annex XVII and, for electronics-adjacent dispensing fitments, RoHS Directive 2011/65/EU as amended by (EU) 2015/863. Terminal parts include tamper-evident beverage caps, nutraceutical lids, dispensing spouts, and overcaps for cosmetic jars.

When Institutional Waste Segregation Film Requires Controlled Opacity Under CONEG and EU Packaging Limits

Blown film lines running 70–120 µm industrial liners require 4–6 wt% loading to achieve sufficiently low light transmission for colour-coded waste segregation; at 2 wt% the tint is visually rejected under high-frequency fluorescent inspection, while above 6 wt% dispersed pigment can act as a stress concentrator and depress Elmendorf tear strength. The film is extruded through a 250–400 mm spiral mandrel die with a 1.8–2.4 mm die gap, at a blow-up ratio of 2.5:1 to 3.2:1 and melt temperature 180–215 °C; frost line height is maintained within ±100 mm of the calibration value to control dart impact anisotropy. The single-screw extruder is specified at 30:1–36:1 L/D with a barrier screw and mixing pins, because the concentrate must be fully homogenized before the melt enters the annular die and any feed surge becomes visible as brown streaking in the film bubble. The colourant package is tested against the heavy-metal concentration limits of EU Packaging and Packaging Waste Directive 94/62/EC, which sets 100 mg/kg total for lead, cadmium, mercury, and chromium VI, and against North American CONEG limits of 100 ppm per metal. Terminal products are beige/tan waste segregation bags, infectious linen disposal bags, pharmaceutical waste liners, and temporary construction barrier film.

Parison Programming and Die Swell Variation with a 3% Beige Concentrate in Extrusion Blow Molding

Extrusion blow molding of 0.8–1.5 mm-thick opaque HDPE/LLDPE bottles uses 2–4 wt% of the LLDPE-based concentrate, with the most significant process impact observed as a 4–7% increase in parison die swell compared with unpigmented resin at the same screw speed. The continuous shuttle or rotary wheel line is operated with a 24:1–30:1 L/D extruder, barrel temperatures from 170 °C to 200 °C, and head tooling adjusted so that parison weight variation across 16 cavities remains below ±1.5%; blow pressure is set at 0.6–1.0 MPa and mould coolant is held at 8–15 °C to prevent bottlenecks on high-output lines. Parison programmers are recalibrated after colour concentrate addition because the changed melt elasticity alters hang time and wall thickness distribution at pinch-off and shoulder regions. Regulatory compliance for chemical and personal-care containers includes UN 3H1 certification for dangerous goods packagings, FDA 21 CFR 177.1520 where the final article contacts food, and EU Regulation 10/2011 for consumer packaging; the colourant must not contribute more than 100 mg/kg total heavy metals under 94/62/EC. Terminal products are 250 mL–5 L opaque cosmetic bottles, household chemical containers, jerrican preforms, and pharmaceutical canisters.

Polyethylene foam sheet and profile extrusion for wood-look underlay and protective padding is another production route in which the beige concentrate is dosed at 2–4 wt% into an LDPE/LLDPE foamable compound containing 1.5–3.0 phr azodicarbonamide blowing agent. The tandem foam extrusion line uses a first extruder to plasticate at 105–115 °C and a second cooling extruder to bring the melt to 95–100 °C before the annular or flat die; gauge reduction and cell integrity depend on controlling die pressure above 6 MPa to prevent premature foaming. Published data for this specific concentrate in foam extrusion is limited, so cell nucleation must be validated on-line because the added pigment can alter nucleation density and increase open-cell content when processing temperatures drift more than ±3 °C from the baseline. The coloured foam is evaluated according to ASTM D3575-20 for compression set and tensile properties, while the heavy-metal profile of the colour concentrate is verified against RoHS Directive 2011/65/EU where the final foam article is incorporated into electrical and electronic equipment, and against REACH Annex XVII for all articles placed on the European market. Terminal products include expansion joint filler strips, anti-vibration underlay for floating floors, protective corner pads, and case inserts.