Lotte Chemical HDPE HIVOREX 2210J is a high-density polyethylene injection-moulding grade supplied in pellet form for rigid packaging, transport crates, tote boxes, beverage crates, agricultural trays, caps and closures, housewares, and industrial containers. The resin is manufactured by a low-pressure catalytic polymerisation route and has a nominal density of 0.955 g/cm³ when tested under ASTM D1505 or ISO 1183-1:2019. Under the 190 °C/2.16 kg condition, the melt index measured by ASTM D1238 or ISO 1133-1:2022 is 6.0 g/10 min. These values define a medium-flow injection grade that combines moderate melt mobility with the stiffness and density of HDPE. The product is neither a pipe-grade nor a film-grade resin; its molecular architecture is adjusted for short-cycle injection moulding, with controlled lot-to-lot consistency and acceptable notched impact strength in thick sections. Lot-specific certificates of analysis should be used to confirm specification limits, because typical published data may vary slightly by production line and feedstock.

How Does 2210J Differ from Blow-Moulding and High-Flow Injection HDPE Grades?

The main differentiator is the melt index of 6.0 g/10 min at 190 °C/2.16 kg. A blow-moulding HDPE grade designed for drums or intermediate bulk containers is usually formulated below 1.0 g/10 min to maintain parison hang strength; 2210J cannot replace such a grade in continuous extrusion blow moulding because the parison elongates excessively at typical blow-loading temperatures. Conversely, a high-flow injection HDPE with melt index above 20 g/10 min fills thin-wall dairy containers and disposable tubs more easily but generally loses notched impact strength and environmental stress-crack resistance. 2210J occupies an intermediate rheological position, allowing fast enough filling for multi-cavity crates and pallet tools while retaining a flexural modulus near 930 MPa under ASTM D790. Compared with a low-flow HDPE injection material used for large structural pallets, 2210J often reduces injection pressure and shortens filling time, but the exact gain depends on wall thickness, gate geometry, and mould temperature.

From a product-selection perspective, the grade should be viewed as a rigid packaging and industrial container material rather than a general-purpose replacement. It is differentiated from high-flow packaging grades by higher melt viscosity, which can limit flow-length-to-wall-thickness ratios in parts thinner than 0.8 mm. At the same time, it is differentiated from low-flow HDPE by lower parison strength, making it unsuitable for blow moulding. In pipe-grade comparisons, PE100 high-density grades may have melt indices near 0.3 g/10 min under the same ASTM D1238 condition to provide long-term hydrostatic strength; 2210J is not approved for pressure piping or for hydrostatic design basis analysis under ISO 9080. These trade-offs define the product application window.

In a reciprocating screw injection machine with a general-purpose polyethylene screw of L/D 18:1 to 22:1 and compression ratio 1.8:1 to 2.4:1, barrel temperatures are normally set from 190 °C at the rear zone to 220 °C at the nozzle. The mould temperature should be maintained between 20 °C and 60 °C; lower values shorten cooling time but can freeze the flow front too early in thin ribs, while higher values improve gate-area impact and surface finish but extend cycle time. Shot volume should not exceed 70% of maximum machine capacity to limit residence time and oxidative degradation. Screw recovery should use a back pressure of 0.5 MPa to 1.5 MPa and peripheral screw speed of 0.15 m/s to 0.30 m/s for screw diameters between 40 mm and 60 mm; higher screw speeds can generate shear heating and shift the melt index above specification, altering part mass and impact properties. Hydraulic injection pressure of 60 MPa to 100 MPa and holding pressure of 40 MPa to 70 MPa are typical starting points for wall sections from 2.0 mm to 3.5 mm. Thin ribs below 1.5 mm may require velocity-controlled filling, increased melt temperature, or sequential valve-gate opening to prevent flow hesitation. On multi-cavity crate tools with hot-runner systems, the primary bottleneck is usually cooling rather than plastication, because the melt index supports rapid screw recovery. Published data for this specific configuration in multi-cavity thin-wall moulds is limited; processing trials should verify gate freeze-off time, cushion stability, and peak injection pressure for each tool.

Principal uses include stackable crates, bottle crates, agricultural trays, industrial tote boxes, pallets, refuse bins, housewares, and general-purpose injection articles. Mould shrinkage under standard injection conditions is anisotropic: typical flow-direction shrinkage falls in the 1.5% to 2.5% range and transverse shrinkage falls in the 1.0% to 2.0% range, depending on packing pressure and part thickness. Packing pressure is the primary control for shrinkage and sink marks in thick bosses, but excessive packing raises part mass and frozen-in stress. For dimensioning crate base grids, tooling should incorporate shrinkage allowances based on actual gate location and cooling layout rather than a single universal value. Surface treatment for printing or labelling may be required because untreated HDPE has low surface energy; corona discharge or plasma treatment should raise wetting tension above 38 mN/m for consistent ink adhesion.

On a production line for stackable crates using a hot-runner tool with 8 cavities, process engineers often set holding time at 4 s to 8 s for a 1.8 mm wall and monitor peak cavity pressure at 30 MPa to 50 MPa; below that range, sink marks may appear in rib intersections. This is a representative field condition, not a universal recipe. Actual gate dimensions, runner balance, and clamp stiffness of the press shift the pressure window. Regrind additions should be validated; industrial experience often starts at 10% to 20% by weight and is increased only after melt-flow and impact checks under ASTM D1238 and ASTM D256. Higher levels may increase density slightly and lower elongation at break, especially when the regrind includes burned material or mixed-colour scrap. A regrind control plan should include melt index check every 4 h and density check under ASTM D1505 to detect lot contamination.

When Frozen-In Stress in Crate Grids Requires Post-Mould Cooling Control

In crates, pallets, and tote boxes with intersecting walls and tapered bosses, rapid cooling can leave frozen-in stress that reduces gate-area impact and stack-load performance. Mould inserts with localised cooling circuits around thick sections are recommended to remove heat uniformly. If the mould temperature is kept below 20 °C, condensation can form on cavity surfaces and produce surface splay or weld-line weakness. If the mould temperature is raised above 60 °C, the cooling time may exceed the filling and plastication time and erode the cycle-time advantage of the medium melt index. In high-speed filling, weld lines can form where flow fronts meet behind cores; gate placement should be arranged to merge flow fronts at low shear and away from high-stress corners. Weld-line integrity can be assessed by notched Izod tests under ASTM D256 or by crate-level compression testing under ISO 12048. Because the product is an injection-moulding HDPE rather than a high-molecular-weight ESCR resin, environmental stress-crack resistance under wet surfactant loading is limited. Applications involving repeated contact with detergent solutions should be validated by ASTM D1693 condition B or by cyclic stack-load trials on finished articles.

When thick sections are unavoidable, post-mould annealing at 60 °C to 80 °C for 30 min to 60 min can relax frozen-in stress and improve crack resistance, but it adds a secondary operation and may alter part dimensions. This procedure is normally reserved for heavy-duty containers or returnable logistics items where service life justifies the added cost. Batch-to-batch variation in melt index may shift filling pressure and part mass; processors should monitor cushion position and peak injection pressure against the initial validation window.

Applications requiring food-contact compliance should be confirmed against FDA 21 CFR 177.1520 olefin polymer provisions and EU Regulation No 10/2011. The resin itself does not guarantee conformity of the finished article; overall packaging compliance depends on the surface-to-volume ratio, migration testing, regrind content, and printing or lamination steps. For outdoor use, uncompounded HDPE without carbon black or UV stabiliser will degrade under prolonged ultraviolet exposure; black compounds or stabilised pigments may be required for returnable transit containers exposed to direct sunlight. The product should be stored in a dry environment and protected from high humidity. Pre-drying is not normally required, but if pellets are stored at relative humidity above 60%, surface condensation can occur during hopper warm-up; drying at 60 °C to 80 °C for 1 h to 2 h may be used when surface defects are observed. Blending with polar polymer residues such as nylon or PET in plant regrind should be avoided because incompatibility can cause delamination and reduced impact strength. These operational boundaries define the practical use window for HIVOREX 2210J in rigid packaging and industrial injection-moulded components.