Polybatch Treated Pine 60175U/4 is supplied in an LLDPE carrier for let-down into polyethylene and polyethylene-rich recycle streams. The carrier’s melt-viscosity bridge and the treated-pine shade are intended for opaque outdoor or structural polyolefin articles; direct food-contact status is not assumed unless lot-specific pigment compliance under the relevant migration framework is documented. The application notes below are organized by downstream processing route, not by market segment, because the same let-down ratio can produce different colour retention depending on residence time, shear rate, and mould or die configuration. Where published data for the specific concentrate configuration are absent, that absence is stated rather than interpolated from dissimilar masterbatch grades.

In wood-plastic composite capstock coextrusion lines using a 75 mm conical twin-screw cap-layer extruder with L/D 27:1 to 34:1 and a 45 mm coextruder feeding an I-shaped deck board die, the concentrate is fed at 2 wt% to 5 wt% into the cap layer stream after the first mixing zone to avoid exposing the pigment to the full residence-time distribution of the primary compounding section. The cap layer matrix is an HDPE-rich skin containing 3 wt% to 8 wt% of coupling agent and 1 wt% to 2 wt% of external lubricant; melt temperature is controlled at 185°C to 210°C and the die exit melt pressure is maintained below 12 MPa to reduce die lip plate-out from low-molecular-weight carrier fractions. At addition levels above 5 wt%, the cap layer flexural modulus measured by ASTM D7032-21 may fall below the span-to-thickness requirement of 16:1 for three-point loading, and the coefficient of linear thermal expansion measured by ASTM D6341 can exceed 8×10⁻⁵ mm/mm/°C, creating a cap/core differential expansion known to cause delamination after 2,000 h of thermal cycling. The finished deck boards and railing profiles are qualified under ASTM D7032-21 for static load, ASTM D256 for notched Izod impact, and ASTM G154 Cycle 1 for 2,000 h UV exposure, with ΔE judged against Type III colour change. Regulatory evidence for the final assembled product includes ICC-ES AC174 acceptance criteria for structural decking and REACH Annex XVII verification for the pigment preparation. If the concentrate is not dried and the storage area exceeds 60% relative humidity, moisture condensation on cold granules entering the feed throat can create surface porosity and starve the cap layer of pigment at the die edge; therefore desiccant drying at 80°C for 2 h is specified when moisture exceeds 0.08 wt%. Avoid combining with amine-based processing stabilizers in the cap layer because the resulting pH shift accelerates the depletion of organic pigments under UVB exposure in accelerated weathering.

What Changes When the Concentrate Is Used in Rotational Moulding of Outdoor Furniture?

The main difference in rotational moulding is that the LLDPE concentrate is dry-blended with pulverized LLDPE or HDPE rotomoulding powder rather than melt-compounded in an upstream extruder. For biaxially rotating cast-aluminium tools producing 8 mm to 10 mm thick park bench slats and playground roof shells, the let-down ratio is held at 1.5 wt% to 3 wt%. The powder blend is prepared in a 200 L high-intensity mixer at 400 rpm for 10 to 15 min; the concentrate pellets are not pre-ground unless the tool contains sharp corners where pellet size can cause dry-spot formation. Oven peak internal air temperature is set to 250°C to 265°C for 25 to 35 min depending on the part wall thickness, and the mould is cooled with forced air at 15°C before demoulding. The biaxial machine is operated with a speed ratio of 4:1 and a minor-axis speed of 6 to 8 rpm. In this process, addition above 3 wt% is avoided because prolonged heating in the oven causes the LLDPE carrier to oxidize at the innermost surface, producing a colour shift and an internal surface roughness that can be mistaken for poor pigment dispersion. Finished park benches and playground components are evaluated under ASTM F1487-21 for impact attenuation, EN 71-3:2019+A1:2021 for migration of metals from toy-adjacent parts, and RoHS 2011/65/EU Annex II for electrical/electronic waste if the furniture contains embedded lighting or sensors. A production-scale failure mode observed in this configuration is warping at the mould parting line when water cooling is substituted for air cooling; the sudden temperature drop produces uneven crystallinity and a visible shade band along the part. The LLDPE carrier’s melt flow index, specified by ISO 1133-1:2022, should be within the same range as the rotomoulding powder to avoid early melting at the wall and pigment accumulation at the powder-void interface. Published data for the specific Treated Pine shade in thick rotomoulded sections are limited; therefore lot-specific accelerated weathering under ISO 4892-2 is recommended before specifying outdoor exposure beyond 2 years.

Under high-cavitation injection moulding of recycled polyethylene outdoor planter pots, the concentrate is dosed at the feed throat with a gravimetric side feeder at 2 wt% to 4 wt% and is not pre-diluted. The injection moulding machine is a 120-ton hydraulic-clamp unit with a 32 mm general-purpose screw with L/D 20:1; barrel zone temperatures are set at 200°C, 215°C, 225°C, and 230°C from feed to nozzle, with the nozzle held at 225°C. Injection speed is adjusted to fill a 1.8 mm to 2.5 mm wall thickness in 0.8 s to 1.2 s, and holding pressure is maintained at 60 to 80 MPa for 4 s to 6 s. The finished articles include 5 L to 20 L injection-moulded nursery pots, saucers, and segmented landscape edging systems with snap-fit joints. Compliance requirements for these non-food outdoor articles are typically limited to RoHS heavy-metal ceilings and, if the edging is installed in public playgrounds, EN 71-3:2019+A1:2021 migration limits. Mechanical performance is verified by ISO 178 flexural modulus, ISO 180 Izod impact at 23°C, and ISO 1133-1:2022 for incoming recycled feedstock because batch-to-batch MFI variation from 5 g/10 min to 20 g/10 min at 190°C/2.16 kg determines the dispersion quality of the concentrate. At 4 wt% or lower addition, the shade is homogenized without visible specking; above 4 wt%, thin-wall parts below 2 mm have shown flow marks and a drop in flexural modulus below 800 MPa. Pre-drying is unnecessary at <0.05 wt% moisture; above 60% RH storage, a 70°C hopper dryer for 2 h prevents splay on the surface.

When Blown Film Lines Run Thin-Gauge Horticultural Mulch at High Draw-Down Ratios

When the concentrate is fed to a 50 mm grooved-feed single-screw extruder with L/D 30:1 producing 25 µm to 50 µm horticultural ground-cover film at a blow-up ratio of 2.5:1 and a die gap of 1.2 mm, the let-down ratio is set at 3 wt% to 6 wt% because thin film cross sections require a higher pigment loading to reach the same surface opacity as a thick-section moulding. The barrel profile is 180°C, 195°C, 205°C, and 210°C, with the die at 205°C to 210°C; air ring cooling is set to 15°C and the frost line is kept at 350 mm to 450 mm above the die. Excessive melt pressure above 35 MPa before the screen pack indicates poor dispersion or inadequate filtration of the post-consumer PE feedstock; a 100-mesh screen pack is used to capture agglomerates before they enter the spiral mandrel die. The film products include nursery overwintering covers, weed-suppression sheeting, and temporary site erosion control films. Quality tests include ASTM D882-18 tensile properties, ASTM D1709-16a dart drop impact on Type A specimens, Elmendorf tear by ASTM D1922-15, and light transmittance measured by ASTM D1003. The horticultural film is not classified as food-contact material; therefore EU Regulation 10/2011 migration testing is applicable only if the film is marketed for direct contact with food produce, which this shade is not recommended for without lot-specific pigment compliance. Processing limitations include reduced bubble stability at loading above 6 wt% because the concentrate increases melt elasticity and can induce draw resonance in gauges below 25 µm; die lip plate-out may also increase at the six o’clock position due to the low-molecular-weight LLDPE fraction. Dryer requirement is 80°C for 2 h if the concentrate has been stored in an unheated warehouse at RH > 60%.

For single-screw profile extrusion of recycled HDPE landscape timbers in rectangular profiles of 40 mm × 90 mm, the concentrate is metered at 2 wt% to 4 wt% into a hopper blend of washed PCR flake and 3 wt% calcium stearate. A 65 mm single-screw extruder with L/D 28:1 and a vacuum vent at 0.08 MPa absolute is used; barrel temperature zones are 185°C to 220°C, the adapter is held at 215°C, and the profile die is heated to 210°C. The vacuum vent removes residual moisture and degradation volatiles from the PCR fraction; if vent port vacuum drops below 0.08 MPa, surface porosity will form and the pine shade will appear mottled. The die is a converging plate design with a drawdown ratio of 1.2:1 and a calibration sleeve maintained at 35°C to 45°C. Finished landscape timbers are used as retaining-wall caps, garden bed borders, and non-structural edging; ASTM D7032-21 applies for structural plastic lumber, while ASTM D256 and ASTM D792 provide impact strength and density checks. No food-contact or potable water compliance claim is available for this route; REACH Annex XVII and RoHS concentration limits for pigments are the baseline chemical restrictions. Batch-to-batch variance in PCR flake MFI from 0.3 g/10 min to 3 g/10 min at 190°C/2.16 kg alters the specific energy input of the extruder; at low MFI, the final profile may exhibit longitudinal die lines due to insufficient melt homogenization. Pre-drying is required at 90°C for 3 h only when the flake moisture exceeds 0.8 wt%.

Extrusion Blow Moulding Colour Stability in Outdoor Waste-Container Geometries

Extrusion blow moulding of 20 L to 100 L outdoor waste containers from HDPE/LLDPE blends uses the concentrate at 2 wt% to 3 wt%, metered directly into the extruder feed of a continuous shuttle-type blow moulding machine with a 65 mm single-screw extruder and a 1.8 kg accumulator head. The melt is processed at 200°C to 220°C and the blow mould is cooled to 10°C to 20°C; parison weight is controlled to ±2 g because colour strength varies with wall thickness and a heavier parison dilutes the pigment in the finished part. Blow pressure is set to 0.6 to 0.8 MPa, and the parison is programmed with a 0.2 mm to 0.5 mm wall thickness profile to maintain uniform shear history. Finished containers are tested under EN 840-1:2020 for mobile waste container design and dimensions, and UV exposure is evaluated under ISO 4892-2 cycle 1 for 1,000 h; changes in tensile elongation at break are measured by ISO 527-3:2018 on specimens cut from side panels. The LLDPE carrier contributes to impact toughness of the base HDPE but added above 3 wt% can soften the container sidewall and reduce stacking force resistance. Incompatibility is noted with certain fluoropolymer processing aids at high dosage because the resulting melt slip can alter pigment dispersion at the accumulator head; if fluoropolymer PPA is used, it should be limited to below 0.05 wt%.