LyondellBasell Icorene 3560 BUE 5775 Polyethylene, Linear Low Density is a butene-based linear low density polyethylene powder supplied for rotational moulding of hollow parts that require a balance of stiffness, environmental stress-crack resistance, and low-temperature ductility. The 3560 portion of the code conventionally identifies a nominal density in the region of 0.935 g/cm³ with a melt mass-flow rate near 5.0 g/10 min at 190 °C and 2.16 kg. When tested in accordance with ISO 1183-1:2019 and ISO 1133-1:2022, typical commercial lots are expected to fall within density limits of 0.934–0.936 g/cm³ and MFR limits of 4.8–5.5 g/10 min, though the current technical data sheet and certificate of analysis remain the controlling specification. The BUE designation is associated with butene comonomer and the 5775 suffix identifies a stabilizer/additive package intended to improve weathering resistance; exact additive chemistry is not disclosed.

In industrial rotomoulding applications, this product class is used for medium-wall agricultural tanks, water storage liners, small chemical containers, and air ducts. The powder sinters and densifies on heated aluminium or steel mold surfaces at typical chamber temperatures of 280 °C to 315 °C. Selection of a butene LLDPE rather than a high-pressure LDPE or an octene LLDPE affects both the mechanical performance of the demoulded part and the cycle time because comonomer type alters melting point, crystallization kinetics, and melt-viscosity development.

What separates butene-based LLDPE rotomoulding powders from high-pressure LDPE, MDPE, and octene-based grades?

Butene-based linear low density polyethylene has a substantially linear chain with short-chain branches distributed along the backbone. This molecular architecture produces a different balance of melt flow and solid-state properties than high-pressure LDPE, which contains long-chain branching. Under ISO 527-2:2012 tensile yield stress measurements, LLDPE rotomoulding grades in this density class typically fall between 14 MPa and 19 MPa, whereas LDPE rotomoulding grades of comparable MFR are usually below 12 MPa. The long-chain branching in LDPE provides higher zero-shear viscosity and better melt stability during long oven residence, but at the expense of tensile strength and environmental stress-crack resistance.

Relative to a high-density polyethylene rotomoulding grade at 0.950 g/cm³, Icorene 3560 BUE 5775 is expected to show lower tensile yield stress and lower flexural modulus, but a longer failure time under environmental stress cracking and better resistance to impact at -20 °C. Relative to an octene-based LLDPE of equal density, the butene comonomer yields slightly lower dart impact and puncture energy; the benefit is generally a narrower melting range and more predictable powder flow in feed systems. These differences are evaluated by ISO 178:2019 flexural modulus, ISO 6603-2:2000 puncture impact, and ASTM D1693-15 condition B ESCR.

Adjacent butene LLDPE grades with lower melt mass-flow rates, near 3.0 g/10 min, may offer higher ultimate tensile strength and slower crack growth, but they require longer oven residence for complete densification. Grades with higher MFR, near 6.5–8.0 g/10 min, flow more readily into complex mold inserts and recesses, but the associated lower molecular weight can reduce stress-crack resistance. Icorene 3560 BUE 5775 is therefore positioned for medium-wall parts in which the 5.0 g/10 min MFR class provides sufficient melt flow without sacrificing long-term stress-crack performance.

Oven residence, peak internal air temperature, and powder particle-size constraints in single-arm shuttle equipment

Rotational moulding of this LLDPE powder is constrained by the internal air temperature profile and the rate of particle coalescence. On a shuttle-type machine with forced-convection air and a swing radius of 2.5 m to 4.0 m, the chamber temperature is typically set at 280 °C to 315 °C; the mold surface reaches a lower peak temperature due to thermal mass. The processing target for this product family is a peak internal air temperature of 195 °C to 205 °C. If the internal air temperature remains below 185 °C for extended periods, partially fused powder deposits are observed at the mold parting line; if it exceeds 215 °C, oxidative degradation may reduce environmental stress-crack resistance and produce color shift. These limits are practical process boundaries for medium-flow butene LLDPE rotomoulding powders, not absolute product values for all tooling geometries.

Particle size distribution influences bubble density and internal surface finish. Rotomoulding powder for this grade family is typically controlled to a D50 between 250 µm and 500 µm with fines below 106 µm limited to less than 10% by sieve analysis in accordance with ASTM D1921-18. Excessive fines increase the specific surface area and accelerate heating, but they may reduce dry flow and create agglomeration in feed hoppers. Bulk density measured by ISO 60:1977 is normally between 0.30 g/cm³ and 0.40 g/cm³; low bulk density increases cycle time because trapped air occupies volume and slows heat transfer.

In double-wall tank tooling with aluminum cast plates and nominal wall thickness of 12 mm to 18 mm, warpage arises during cooling when the inner air layer cools more slowly than the outer surface. Air quench with forced blowers followed by water mist at 3–5 L/min per mold surface is used after demolding temperature drops below 70 °C. Free-cooling too slowly maximizes crystallinity and increases shrinkage to 2.0–2.5%; rapid cooling can freeze residual stress and reduce low-temperature ductility. On production-scale shuttle machines, the mold rotation ratio is often set at 4.0:1 for cylindrical tanks and 1:5 for certain flat duct geometries; the actual ratio should be selected from trial results for the tooling because the ratio changes wall thickness distribution.

When large double-wall storage tanks require low-temperature ductility after demoulding

Hollow chemical storage tanks, agricultural sprayer tanks, and air ducts rotomoulded from this product family may be exposed to impact at -20 °C and -40 °C. The butene-based LLDPE architecture provides a lower ductile-to-brittle transition temperature than a similar-density HDPE, but lower puncture energy than an octene-based LLDPE at equal density. Low-temperature impact tests on test plaques are conducted under ISO 6603-2:2000. Published data for this specific product configuration is limited; comparative product testing on production-scale parts should be used to establish the minimum service temperature for a defined wall thickness and drop energy.

Environmental stress-crack resistance is a key differentiator against HDPE rotomoulding grades. The branched LLDPE structure delays crack propagation under Igepal CO-630 exposure in accordance with ASTM D1693-15 condition B. Products in this density range often reach 1000 h without failure at 50 °C, whereas conventional HDPE of density 0.950 g/cm³ may fail before 200 h under the same test. The actual result is influenced by the stabilizer package and molded-in stress; published data for this specific product configuration is limited.

In outdoor service, the 5775 additive package is expected to contain a hindered amine light stabilizer and a phenolic antioxidant; however, the exact additive formulation is proprietary. Accelerated weathering comparisons under ISO 4892-2:2013 method A evaluate color retention and surface cracking. UV-stabilized rotational moulding grades of the butene LLDPE class typically retain more than 50% elongation at break after 3000 h xenon-arc exposure, but the current product data sheet should be consulted for the exact retained property value because antioxidant type and cooling rate during moulding shift the result.

For food-contact applications, compliance must be verified against the specific additive package. Olefin polymers may be referenced under FDA 21 CFR 177.1520 and EU 10/2011 as amended, but a specific migration declaration is outside the scope of this introduction. For potable water tanks, regulatory approvals are application-specific and depend on the molded article, not solely the resin.

Process incompatibility arises when the powder is contaminated with silicone release agents, mineral oil, or other hydrocarbon lubricants. These materials reduce particle agglomeration and can produce pinholes at the mold surface. Strong oxidizing agents and prolonged contact with unsaturated oils may reduce oxidative stability; the additive package should not be combined with unknown metal stearate levels because residual calcium or zinc stearate can alter process behavior and affect color after weathering.

Moisture uptake in polyethylene powder is low, but sacks stored below the dew point can condense surface water. Production-scale handling typically conditions the powder to 23 °C ± 2 °C and 50% ± 10% relative humidity for at least 24 h before charging to the mold. Drying at 70 °C for 2 h is sufficient to remove surface moisture; desiccant drying is not required for polyethylene.