LyondellBasell Icorene 3560 GRN 6133 is defined as a linear low density polyethylene supplied in pulverulent form for rotational moulding, with the green coloration incorporated under the code GRN 6133 rather than added as an external dry colourant. The base resin belongs to the ethylene-alpha-olefin copolymer class and is distinguished by a nominal density of 0.935 g/cm³ when tested to ISO 1183-1:2019 and a melt flow rate of 5.0 g/10 min at 190 °C/2.16 kg according to ISO 1133-1:2022. These values locate the grade in the medium-density segment of the LLDPE rotational-moulding range, in which the density-modulus relationship and low-temperature impact response are balanced for thick-walled hollow parts. The powder morphology is intentional: dry-flow characteristics, bulk density, and particle size distribution are controlled to permit uniform wall build-up in uniaxial and biaxial rotating tools. The GRN 6133 colour designation indicates a specific pigment formulation, and the addition of inorganic and organic colourants can alter crystallisation rate, surface finish, and long-term colour retention relative to the natural base resin.

Nominal property profile aligned with ISO and ASTM methods

Manufacturer-published values for the natural resin are used as design inputs; the green-compounded variant is expected to exhibit small shifts because the pigment particles act as heterogeneous nucleation sites and reduce the effective load-bearing polymer cross-section. The following values are representative for compression-moulded or rotomoulded test plaques, depending on the method specified.

Because rotational moulding produces non-uniform cooling through the wall, tensile and impact values on finished parts may be lower than those obtained from ISO 527-2:2012 test plaques. The difference is largest in sections thicker than 6 mm, where internal cooling is slower and core crystallinity is higher. Lot-specific certificates of analysis should be consulted for melt flow rate and density, because the colour concentrate and pulverisation history can shift the melt flow rate by ±0.5 g/10 min relative to the nominal value.

Rotational moulding with this grade is normally performed with a pulverised feedstock having a particle size distribution in which at least 90% of the material passes through a 35 mesh (500 µm) screen and no more than 10% is retained on a 35 mesh screen. The dry-flow time measured on a 100 mm-diameter funnel is generally below 30 s per 100 g; values above 45 s indicate static charge, high fines content, or moisture. Powder is added to the cold or preheated mould at a controlled fill ratio, typically 3.0:1 to 4.5:1 by weight relative to the finished part weight for single-layer products. Oven temperatures are set between 250 °C and 300 °C, and the peak internal air temperature is controlled in the range 190 °C to 215 °C for most tooling; the exact peak internal air temperature is established by thermocouple logging and is adjusted when wall thickness is outside the tolerance band.

On multi-arm carousel machines, cycle time is typically governed by the heating and cooling phases; the grade exhibits a sintering plateau in which the powder coalesces into a continuous melt film before full densification. If the internal air ramp is too aggressive, under-sintered zones appear as pitted inner surfaces and low-density white spots near ribs or inserts. If the oven residence time exceeds 30 min at 280 °C, oxidative yellowing of the green surface and a measurable reduction in impact strength can occur, particularly in the inner wall where oxygen from the internal air remains in contact with the melt. In beryllium-copper tools, heat transfer is rapid; in cast aluminium tools, the lower thermal diffusivity requires an oven temperature increase of 10 °C to 20 °C or a heating time extension of 8 min to 12 min to reach the same peak internal air temperature. Shot-to-shot wall-thickness variation is controlled primarily by fill weight and tool speed ratio rather than by temperature alone; production logs from carousel lines routinely show thickness variation below ±10% when fill weight is held to ±1%.

The crystallisation behaviour of the grade has direct consequences for wall shrinkage and warpage. Isothermal crystallisation at 120 °C is frequently monitored by differential scanning calorimetry in the plant; the half-time of crystallisation for this class of LLDPE typically falls between 3 min and 8 min, depending on pigment nucleation. Faster crystallisation induced by the green pigment can increase shrinkage anisotropy in thick sections and must be offset by reducing final cooling rate or increasing mould release pressure. In water-cooled moulds, internal air pressure is usually maintained at 0.2 bar to 0.5 bar during cooling to control wall contraction and prevent pull-away from the tool surface; without positive pressure, the inner surface may develop cooling-related depressions. The optimal mould release temperature for this material is generally below 70 °C, because demoulding at higher temperatures can cause dimensional distortion in large flat panels.

Data generated on compression-moulded plaques according to ISO 293:2019 do not always transfer to rotationally moulded parts because the cooling rate and oxidation history differ. The tensile yield strength measured on rotomoulded plaques may be 5% to 15% lower than compression-moulded values, while elongation at break may remain above 500% unless internal porosity exceeds 3%. Notched impact values depend strongly on specimen thickness and notch radius; ISO 180:2019 with a Type A notch and 4 mm thickness is often specified. The use of a single property value from a datasheet without reference to the sample preparation method can lead to under-specified parts in mechanical design.

The melt flow rate of 5.0 g/10 min is a single-point low-shear measurement and does not fully describe the rheological response under the near-zero-shear conditions of rotational moulding. A high-load melt flow ratio using 21.6 kg load is sometimes employed for internal specification, but published data for this specific green-compounded configuration is limited. Molecular architecture controls bubble dissolution; residual bubbles reduce density and act as stress concentrators. In quality tests, a density value below 0.920 g/cm³ on a moulded wall indicates incomplete sintering or excessive moisture and triggers rejection in pressure-containing parts.

What operational boundaries govern this colour-compounded powder?

The powder should be stored below 40 °C and below 60% RH; condensation on the powder surface is a known cause of pinholes in finished walls. Although polyethylene is not hygroscopic, surface moisture can interfere with pigment dispersion and produce surface defects. If storage has occurred above 60% RH, pre-drying in a desiccant-bed dryer with an inlet dew point below -20 °C is recommended at 50 °C for 2 h to 4 h. The product should not be melt-mixed with amine-based antistatic additives, certain metallic stearates, or copper-containing stabiliser packages because these additives can consume phenolic antioxidants and reduce oxidative induction time below 20 min when measured by ISO 11357-6:2018 at 200 °C. Strong oxidising acids, especially concentrated nitric acid at service temperatures above 40 °C, can initiate surface oxidation and stress cracking; polar surfactants and unsaturated hydrocarbons can lower environmental stress crack resistance in pressurised service.

The GRN 6133 designation does not guarantee identical weathering performance to natural or black compounds. Green pigments, particularly phthalocyanine types, can absorb in the visible and ultraviolet regions and may reduce surface gloss loss more slowly than organic yellow or red pigments, but they do not provide the same ultraviolet screening as carbon black. For exterior parts with a service life greater than 5 years, the stabiliser formulation should be specified at the weathering level, not only at the base process-stabilisation level. Accelerated weathering to ISO 4892-2:2021 cycle 1 on 3 mm rotomoulded plaques is used to generate colour shift and chalking data; acceptance limits of Delta E below 5 and gloss retention above 60% are common but are not universal.

Rotational-moulded components made from Icorene 3560 GRN 6133 are encountered in vented chemical storage tanks, water treatment enclosures, agricultural hoppers, outdoor machinery covers, and insulated cooler bodies. In such applications the design is normally governed by ASTM D1998-21 for polyethylene tanks or by proprietary finite-element analysis using notched impact data at the lowest service temperature, often -40 °C. The green colouration is suitable for parts requiring integral pigmentation, but the outer surface should still be evaluated for colour retention under ISO 4892-2:2021 xenon-arc weathering. For potable water contact, certification to NSF/ANSI/CAN 61 is required for the finished part and is not automatically conferred by the base resin alone; the GRN 6133 pigment formulation must be included in the extraction test. For food-contact use, the formulation may be evaluated against FDA 21 CFR 177.1520(c) and EU Regulation 10/2011, with specific attention to pigment purity and migration of colourant-related metal ions.

When this grade is used in two-layer structures with a foamed core or an outer high-density polyethylene shell, the interface temperature must remain above 180 °C during the second layer charge to permit molecular interdiffusion and acceptable peel strength. In drop-weight impact tests, interlayer adhesion failures are often traced to insufficient peak internal air temperature after the second layer charge; a minimum peak internal air temperature of 200 °C for 5 min has been used on production-scale rock-and-roll machines, though published data for this specific configuration is limited.

When substitution of LDPE or HDPE is evaluated in rotational moulding

Substitution of a low-density polyethylene homopolymer with this LLDPE grade generally increases tensile yield strength and environmental stress crack resistance while reducing melt flow at equivalent density. The comonomer distribution produces a higher proportion of tie molecules between lamellae, which improves notched impact at low temperature but raises the yield strength less than an HDPE grade with comparable melt flow. Conversely, replacement of a high-density polyethylene rotational-moulding grade with this material lowers flexural modulus and top-load resistance while improving impact and reducing moulded-in stress. The difference is most visible in stiffness-dependent designs such as large flat sidewalls, where a modulus reduction from approximately 900 MPa for an HDPE grade to 550 MPa for this LLDPE grade can require thicker walls or ribbing to maintain service deflection limits.

Compared with metallocene-catalysed LLDPE grades, the broader molecular weight distribution of a Ziegler-Natta product can provide lower warpage and a wider processing window in thick parts, but metallocene grades may exhibit higher dart impact at the same melt flow rate and density. Published rheological data for the green-compounded variant is limited; therefore, capillary rheometry per ISO 11443:2021 is recommended before transfer between machines with different oven airflow and rotational speed control. Melt viscosity in rotomoulding is not the primary flow mechanism, but it influences bubble release and surface levelling; incomplete bubble release results in internal porosity that is best measured by density column or microscopy rather than by visual inspection alone.

In-process quality control for this grade typically includes melt flow rate, density, dry-flow time, and particle size distribution on each lot, with rotationally moulded test plaques for tensile and notched impact. The green pigment content is verified by ashing or X-ray fluorescence if inorganic pigments are used; lot-to-lot colour is assessed spectrophotometrically against a master standard using ISO 11664-4:2021. Because the GRN 6133 colour package can alter surface finish and welding behaviour, processors should not use natural-resin processing parameters without adjustment. The grade is designed for industrial rotational moulding and is not recommended for blown film, blow moulding, or injection moulding unless specific conversion trials demonstrate processability.