Borealis HE1355 is a high-density polyethylene injection moulding grade with a melt flow rate of 5.5 g/10 min at 190 °C under 2.16 kg load measured to ISO 1133-1:2022, a density of 0.958 g/cm³ measured to ISO 1183-1:2019, a tensile yield stress of approximately 27 MPa measured to ISO 527-2:2012, and a flexural modulus of approximately 1200 MPa measured to ISO 178:2019. In beverage closure production, the grade is processed on high-cavitation moulds of 16 to 48 cavities, with barrel temperatures ramped from 180 °C in the feed zone to 210–220 °C at the nozzle, and hot runner temperatures held between 210 °C and 230 °C. The closing ring and tamper-evident band require consistent melt cushion control; screw retraction after hold should not exceed 2 mm to avoid gate freeze-off at the hot-tip or tunnel gate. Injection speeds of 120–180 mm/s are typical for 1.8–2.5 g caps, with holding pressure between 35 MPa and 50 MPa hydraulic and back pressure at 5–10 bar. Mould temperature is maintained at 10–30 °C to reduce cycle time, but mould surfaces below 10 °C can create condensation and surface splay in high-humidity plants. Cycle times on 32-cavity closure lines fall between 4 s and 7 s, depending on cap mass and cooling channel layout. For still water and non-carbonated beverage caps, 100 wt% HE1355 is used without added impact modifier. For carbonated soft drink closures, a blend of 80–90 wt% HE1355 with 10–20 wt% hexene-based LLDPE is sometimes introduced to improve hinge integrity and stress cracking resistance at the knurl, at the cost of a flexural modulus reduction of roughly 10–15% relative to the neat grade; the exact reduction is grade-dependent and published data for this specific configuration is limited. Slip and antiblock masterbatches, when specified, are typically added at 1–2 wt% and must be selected from FDA-compliant carriers. The terminal components are 29/25 mm and 30/25 mm HDPE beverage closures, sports drink caps, and tamper-evident bands. Regulatory compliance for food-contact use is covered by EU Regulation (EU) No 10/2011 overall migration limits and FDA 21 CFR 177.1520(c) for olefin polymers.

What Flow Length Limits Are Encountered at 0.8 mm Wall Thickness?

In thin-wall dairy cup and margarine tub production, HE1355 is injected at melt temperatures of 220–240 °C with injection speeds from 150 mm/s to 250 mm/s. The mould temperature is set between 15 °C and 30 °C to balance part release and label adhesion in in-mould labelling cells. At a nominal wall thickness of 0.8 mm, the flow length to wall thickness ratio reachable in production tooling is generally in the order of 150:1 to 200:1, depending on gate geometry, runner diameter, and melt temperature; for 200 ml cups with a flow path of 120–150 mm, this corresponds to a fill pressure of 90–120 MPa at the injection unit. Holding pressure is staged from 50 MPa for 0.5 s to 30 MPa for 1.5 s, then released before the gate seal time to prevent sink marks at thicker rim sections. Cycle times of 4–6 s are achievable on 8-cavity in-mould labelling cup lines with ejector stroke capacities above 100 mm. The narrow molecular weight distribution and MFR of 5.5 g/10 min keep the melt viscosity sufficiently low for high-speed filling, but shear heating under 250 mm/s injection speed should be monitored; melt temperatures above 260 °C can cause odour and a visible surface haze in translucent cups. Each cavity is typically equipped with a hot runner valve gate; gate diameters of 0.8–1.2 mm are used to limit gate vestige. The terminal parts are 125 g margarine tubs, 200–500 ml dairy cups, and thin lids for spreading fats. Food-contact compliance includes EU Regulation (EU) No 10/2011 with an overall migration limit of 10 mg/dm², tested under EN 1186-1:2002 and EN 1186-3:2002 for aqueous simulants, and FDA 21 CFR 177.1520 for use conditions A through H.

For returnable crates, pails, and pallets, HE1355 is dry-blended at the hopper with a HALS-based UV stabilizer masterbatch at 1.5–2.5 wt% and, in black outdoor grades, with a 40% carbon black masterbatch at 2–3 wt%. The melt temperature is held at 200–230 °C, and mould temperature is set to 15–25 °C to control warpage in deep-draw geometries. Injection moulding machines for 20 L pails require clamp forces in the range 5000–8000 kN, with shot sizes adjusted to deliver 700–1100 g per pail depending on wall thickness and lid seat design. Holding pressure is maintained at 40–60 MPa for 4–8 s to pack the thick corner sections, followed by cooling times of 15–25 s for pails with nominal wall thickness of 1.8–3.5 mm. Crates and pallets use lower holding pressures and longer cooling due to ribbed structures; sink marks are controlled by rib-to-wall ratios below 0.6:1 and by gas counterpressure where available. Mechanical acceptance is based on Charpy notched impact testing according to ISO 179-1:2010 at 23 °C and, for cold-chain use, at -30 °C; environmental stress cracking resistance is assessed under ASTM D1693 condition A in 10% Igepal CO-630 at 50 °C. Published data for HE1355-specific ESCR at high wall thickness is limited, but HDPE injection grades with 0.958 g/cm³ density typically fail below 30 h if contaminated with low-molecular-weight process aids; therefore no external lubricants are used in this segment. For detergent and agrochemical pails, the finished container is qualified under UN dangerous goods packaging performance tests applicable to 1H2 plastics boxes and jerricans, including drop tests and stack load tests. The terminal products are returnable transit crates, 20 L detergent pails, pallet boxes, and outdoor storage bins.

When Overall Migration Limits Govern Dairy Tub Production

In food packaging, the grade is not treated as a single compliance point; the complete formulation, including colour masterbatch, slip additives, and nucleating agents, falls under the same migration testing scope. Under EU Regulation (EU) No 10/2011, high-density polyethylene used as a food-contact polymer is subject to an overall migration limit of 10 mg/dm² for all food simulants, with the test performed according to EN 1186-1:2002 and EN 1186-3:2002 for aqueous, alcoholic, and acidic food simulants. For dairy tubs operating with fat-containing foods, the relevant simulant is D1 (50% v/v ethanol) or D2 vegetable oil, depending on the intended use; the latter requires replicate extraction because polyolefin absorption of oil can complicate mass-balance calculations. The specific migration of additives is evaluated only if the additive has a specific migration limit listed in Annex II; the base HDPE polymer itself is exempt from specific migration limits, but residual catalyst components such as titanium and aluminium are controlled in the material specification. For export to the United States, FDA 21 CFR 177.1520(c) applies to olefin polymers; this citation covers high-density polyethylene for food contact but does not automatically cover colour concentrates, which must be evaluated independently under 21 CFR 178.3297 or an applicable food additive petition. Processing at melt temperatures above 220 °C does not require pre-drying at relative humidity below 60%, but condensation can increase moisture in the hopper; HDPE is non-hygroscopic, so pre-drying is not used unless the material has been stored in damp conditions or regrind carries surface moisture. Regrind addition up to 20 wt% is common in dairy tub production, but the material must be infrared-sorted or full-colour-stable to avoid black specks. Terminal products are single-use dairy cups, margarine tubs, and lids that require sensory neutrality tested by DIN 10955-1:2004 or an equivalent taste and odour panel method.

Rigid Consumer Storage and Appliance Housings

In non-food injection moulding, HE1355 is processed without a pre-drying step unless the regrind fraction exceeds 30 wt% and has been stored in unlined containers. Melt temperature for houseware boxes and appliance housings is set at 210–230 °C, with the mould at 20–35 °C to reduce surface stress whitening at ribs and bosses. Injection speeds are moderate, 80–150 mm/s, to prevent jetting in flat-panel geometries with wall thickness between 1.2 mm and 2.5 mm. For rigid storage boxes, 100 wt% HE1355 is typical; for cost-reduction programmes, 20–30 wt% post-consumer recycled HDPE is blended at the machine hopper, but this reduces tensile yield stress by 5–12% depending on the recycled stream and increases lot-to-lot variability in Charpy impact by up to 15%. The material is not recommended for thin-wall live hinges where repeated flexing exceeds 10,000 cycles without modification; if hinge performance is required, the hinge should be redesigned with a minimum thickness of 0.3–0.5 mm and gated perpendicular to the hinge line. Compliance for this segment is governed by REACH Article 33 SVHC communication requirements, RoHS Directive 2011/65/EU Annex II restriction limits for lead, cadmium, mercury, hexavalent chromium, PBB, and PBDE, and, for toy-adjacent storage articles, EN 71-3:2019 migration limits for nineteen elements. Terminal products include stackable storage boxes, appliance housings, and small furniture components.

For flip-top and push-pull closures used in personal care and pharmaceutical packaging, HE1355 is moulded at a lower melt temperature of 190–210 °C to suppress formation of low-odour degradation products, because the closure is in direct or indirect contact with lipid-based formulations that can sorb volatile species. Mould temperature is kept at 10–20 °C to freeze the hinge surface quickly and improve cycle time; internal threads are formed by unscrewing cores or collapsible cores, with a valve gate located at the top centre of the closure. The grade is used at 100 wt% in this segment; external lubricants and amide-based slip additives are excluded unless they are supported by extraction data, because amide migration can exceed the sensory threshold in cosmetic emulsions and oral pharmaceutical solutions. Additive masterbatches are restricted to 1 wt% maximum and must be tested for USP <661.1> plastic packaging extractables and Ph. Eur. 3.1.3 polyolefin requirements where relevant. Injection pressure is set between 60 MPa and 90 MPa, with holding time of 1–2 s for closures weighing 1.5–3.5 g. Cycle time on 24-cavity unscrewing tools is 8–12 s, extended by the unscrewing sequence rather than cooling. Terminal components are shampoo flip-top caps, pump overcaps for lotion bottles, and pharmaceutical bottle closures requiring child-resistant features. Regulatory submissions for pharmaceutical packaging reference ICH Q3D elemental impurity limits and USP <661.1> plastic packaging chapters, while cosmetic packaging falls under Regulation (EC) No 1223/2009 Article 17 for the safety of packaging materials in contact with cosmetic products.