LyondellBasell Icorene 3545 RED 4106 Polyethylene, Linear Low Density is supplied as a pre-coloured rotational moulding powder based on a linear low-density polyethylene carrier. The grade identification combines the Icorene 3545 base resin and the RED 4106 colour formulation, meaning the pigment and stabiliser system are compounded into the powder before packaging. The material is charged directly into sheet-steel, stainless-steel or cast-aluminium moulds on single-shuttle, drop-arm, carousel, rock-and-roll or electrically heated multi-axis machines. The LLDPE backbone provides higher low-temperature impact than many HDPE rotomoulding grades and greater stiffness than plastomer-modified LLDPE formulations, while the pre-compounded red pigment eliminates dry masterbatch blending at the moulding cell. The removal of a separate pigment addition step is relevant where powder handling creates combustible dust zones; plant risk assessments under NFPA 652 or local ATEX directives govern housekeeping, grounding and ventilation requirements.

Because the product is a furnace-grade powder rather than an injection-moulding or film resin, the particle size distribution is designed for powder flow and densification during biaxial rotation. Rotomoulding powders in this class commonly have a median particle size near 250–500 µm and are characterised by dry-flow funnel time under ASTM D1895-96. Published data for the exact red 4106 lot configuration is limited; the certificate of analysis should be consulted for particle size, melt flow rate, moisture and colour tolerances. The powder should be stored in sealed containers at temperatures below 30 °C and protected from direct sunlight to avoid premature degradation of the stabiliser package. When material is moved from an unheated warehouse into a warmer moulding bay, a tempering period of 12–24 h is recommended to prevent condensation on cold powder surfaces.

What property profile is specified for the 3545 base and its red-pigmented derivative?

Published technical literature for the natural Icorene 3545 base commonly lists a melt flow rate of 4.0 g/10 min at 190 °C/2.16 kg under ISO 1133-1 and a density of 0.934–0.936 g/cm³ under ISO 1183-1. The red 4106 variant may shift flow by up to ±0.5 g/10 min because of pigment solids and dispersion aids; actual lot-specific values must be read from the certificate of analysis. The table below consolidates the representative property envelope for the uncoloured base and the applicable test designations.

For the red-pigmented material, notched impact and elongation at break can differ from the natural base because organic red colorants and inorganic heat-stabiliser systems may alter crystallisation behaviour. Final properties are also dominated by moulding conditions; an improperly fused part can show impact retention below the inherent capability of the raw powder because peak internal air temperature below 180 °C can result in poor densification and reduced notched impact under ISO 179-1/1eA. Incoming inspection should record melt flow rate, density, dry-flow funnel time and moisture content, while mechanical acceptance should be performed on moulded plaques demoulded according to the same cycle as production parts.

When red pigment alters radiant heat absorption in a drop-arm oven

On drop-arm and shuttle machines, a heavily pigmented red powder can absorb radiant heat faster than natural or pale grades. When a cavity-mounted thermocouple is used, the internal air temperature may therefore reach the target band of 190 °C to 205 °C in a shorter time. Process engineers often reduce the oven setpoint by 5–10 °C when changing from natural Icorene 3545 to the RED 4106 formulation. Internal air temperature should be held within the target window for 2–4 min; excursions above 205 °C for more than 3 min increase the risk of surface oxidation, gas-bubble formation and inner-surface embrittlement. The process window is therefore narrow, and multi-channel internal air-temperature logging is required to establish the cold and hot regions of each tool.

Cast-aluminium moulds of 6–10 mm wall thickness transfer heat differently from sheet-steel tools of 3–6 mm thickness. Production experience indicates that wall-thickness variation on steel tanks can often be held within ±10 % when the powder is dry and the rotational speed ratio is stable; complex geometries can exceed this value. Moisture above 0.1 % by mass, measured by ISO 15512, may generate steam voids and inconsistent melt-out. Where relative humidity exceeds 75 %, pre-drying at 60–70 °C for 1–2 h in a dehumidifying hopper is recommended before charging. Static charge can cause powder adhesion to cold mould surfaces; conveying velocity should be limited to 20 m/s to reduce fines and dust-explosion risk. The fines fraction below 125 µm should remain below 10 % of total powder mass to maintain dry-flow consistency and prevent bridging in feed hoppers.

The zero-shear viscosity of the base grade is not always published but is reflected in the melt flow rate. The powder begins to densify when the internal air temperature passes the crystalline melting range of 122–127 °C; the melt then spreads over the mould wall by gravity and rotation. Primary-axis speeds of 6–10 rpm and secondary-axis speeds of 1.5–3 rpm are representative for many multi-axis machines. Speeds below 6 rpm can promote sagging in deep-draw areas, while speeds above 10 rpm can fling powder and reduce residence time. The rotational speed ratio between primary and secondary axes is commonly set at 4:1 to 6:1 for symmetrical parts; non-symmetrical parts may require variable speed programmes.

After the oven cycle, air cooling is applied first; water mist or forced-air/water spray is introduced only after the mould surface falls below 90 °C. Demoulding is normally performed below 65 °C. Rapid quenching can increase warpage on flat tank panels because the red pigment creates a larger surface-to-core temperature gradient. Semi-permanent release agents based on organo-silicone or PTFE dispersions are used to prevent sticking; excessive release-agent build-up reduces gloss and complicates decoration or repair welding. Field failure modes observed on rotomoulded tanks include local thinning at sharp corners, porosity at knit lines and pinholes in areas where powder failed to sinter. These are associated with insufficient peak internal air temperature, excessive moisture or improper mould release. The red pigmentation can mask surface porosity visually; internal pressure testing may be required for fuel or chemical tanks.

Rotational moulding applications for Icorene 3545 RED 4106 include hollow storage tanks, agricultural chemical reservoirs, water treatment vessels, marine buoys, outdoor equipment housings and playground structural shells. The pre-coloured surface eliminates post-mould painting and associated solvent emissions; pigment is dispersed during compounding and is not expected to rub off under normal abrasion. For outdoor service, the UV-stabiliser package is evaluated by accelerated weathering under ISO 4892-2, with 0.51 W/m² at 340 nm or equivalent, but final qualification should include the intended exposure regime because accelerated data do not always correlate with multi-year field performance in high-UV geographies. Chemical resistance to dilute acids, alkalis, alcohols and aqueous salt solutions is evaluated under ISO 175; prolonged immersion in strong oxidising acids, aromatic hydrocarbons or chlorinated solvents is not recommended for the LLDPE base.

Food-contact and potable-water certifications are not automatically conferred by the base resin. In the United States, a natural LLDPE base may be covered under 21 CFR 177.1520, but the colourant must separately comply with 21 CFR 178.3297; the blended product status must be confirmed with the supplier. The 4106 red formulation includes a pigment package that must be separately assessed under the relevant national or regional food-contact regulation. Similarly, toy applications require migration testing under EN 71-3; the grade should not be assumed compliant without test data. For industrial containers subject to the transport of dangerous goods, the moulded part must undergo type testing according to the applicable UN packaging code; the resin itself does not provide certification.

Differential positioning versus HDPE, MDPE and plastomer-modified rotomoulding grades

The structural distinction between this LLDPE grade and HDPE rotomoulding powders is the short-chain branching distribution along the polymer backbone. Icorene 3545 RED 4106 typically exhibits higher notched Charpy impact at −40 °C and better environmental stress crack resistance than many HDPE grades, but lower flexural modulus and Vicat softening point. HDPE grades usually provide higher stiffness, higher heat-distortion resistance and lower hydrocarbon permeation, making them selected for aggressive chemical containment when high impact is not the limiting factor. MDPE grades occupy an intermediate position; their lower melt viscosity can improve densification and reduce cycle time, but they may not match the low-temperature ductility of this LLDPE. Plastomer-modified LLDPE or very low-density polyolefins give greater impact and ESCR but reduce flexural modulus, increase surface tack and raise compound cost; they are selected only when extreme low-temperature fracture resistance is required.

Within the Icorene portfolio, the natural 3545 base is used where uncoloured parts are acceptable. The RED 4106 variant carries the same base polymer but a fixed pigment letdown ratio. Compared with dry mixing of natural powder and red masterbatch at the machine, the pre-coloured product reduces lot-to-lot variation in pigment concentration, prevents segregation during silo transfer, and allows a single powder feed to the mould. This is a processing and colour-consistency distinction, not a change in the base-resin density class. Processors switching from natural Icorene 3545 to RED 4106 may need to lower oven setpoint by 5–10 °C and shorten peak dwell; switching from an HDPE red compound to this LLDPE grade may require the opposite adjustment.

Operational boundaries apply. The powder is not intended for injection moulding, film extrusion or pipe extrusion; its morphology and stabiliser system are optimised for slow heating under biaxial rotation. Attempts to feed the powder directly to a single-screw extruder can produce surging and inconsistent melt temperature. The grade should not be blended with hygroscopic fillers, conductive carbon black or amine-based flame retardants without compatibility testing, because such additives can increase water uptake, disrupt dispersion or create localised degradation sites. Where electrostatic dissipative or conductive properties are required, the base material is not inherently dissipative; volume resistivity is typically above 10¹⁵ Ω·cm under IEC 62631-3-1 unless a separate antistatic formulation is used. Batch-to-batch variation in the pigment may shift melt flow rate by ±0.5 g/10 min; processors should re-validate oven cycle time when a lot change is received.

The red colour package may fade under extended UV exposure. Colour tolerance on moulded plaques is generally controlled to ΔE 1.0 or less under CIELAB D65/10 conditions, but outdoor reds can show gloss loss and ΔE drift before mechanical property loss. Users should specify acceptance criteria for both colour shift and impact retention after weathering. Under REACH Regulation (EC) No 1907/2006, polymer monomers and additives must be registered and SVHC content must remain below the communication threshold. Under RoHS Directive 2011/65/EU, the homogeneous material must not exceed 0.1 % lead, 0.1 % mercury, 0.01 % cadmium and 0.1 % hexavalent chromium by weight. The red colorant should be free of cadmium sulfoselenide pigments, but the certificate should confirm this. The product should not be default-certified for food contact, potable water or toy use; migration testing and organoleptic evaluation are required for each final article.