Injection moulding of chilled dairy cups from CREOLEX K4750 begins with a melt temperature of 190–215 °C measured at the nozzle and a screw back pressure of 5–8 MPa. The grade's melt mass-flow rate of 50 g/10 min at 190 °C/2.16 kg per ISO 1133-1:2022 and density of 0.953 g/cm³ per ISO 1183-1:2019 allow flow length-to-wall-thickness ratios above 250:1 in multicavity stack moulds. All-electric injection moulding machines with clamp force between 1,500 kN and 4,500 kN are commonly specified, using general-purpose screws with an L/D ratio of 20:1–24:1 and a compression ratio of 2.0:1–2.5:1. The polymer is non-hygroscopic; drying is not required unless condensation occurs at relative humidity above 80%, in which case hopper drying at 60–70 °C for 2 h prevents surface splay on the cup sidewall.

Direct food-contact compliance for the finished cup is verified under FDA 21 CFR 177.1520(c) as an olefin polymer, EU Regulation 10/2011 Annex I with an overall migration limit of 10 mg/dm² in the appropriate food simulant, and GB 4806.6-2016 for the Chinese national standard. The formulation is normally 100% virgin K4750; up to 20 wt% clean in-house regrind from sprues and runners may be blended when the regrind is generated from the same food-contact lot and kept free of non-food scrap. Slip addition for denesting, where required, is limited to 500–1,000 ppm erucamide, and the slip package must be pre-approved for fatty food simulants under EU 10/2011. No plasticiser is used, and any colour masterbatch must be listed for food-contact use because HDPE does not bind polar pigments strongly.

Mould temperature is held at 10–30 °C; wall sections of 0.40–0.60 mm require injection speeds above 300 mm/s to prevent flow hesitation at the rim. Holding pressure of 45–65 MPa hydraulic is applied until gate freeze, typically 0.8–1.5 s. Cooling time for a 0.50 mm wall in a 125 mL cup ranges from 4.0 s to 6.0 s, depending on coolant turbulence and core diameter. Overall dry cycle times of 6.5–9.0 s are observed on 4-cavity and 8-cavity stack moulds, but published data for this specific configuration is limited because demoulding stroke and label-insertion automation often dominate the cycle. Warpage is controlled by maintaining a mould temperature differential below ±2 °C across the cavity surface and by balancing gate location so that the melt front reaches the rim within 0.1 s across all cavities. Finished components include 125–250 mL yogurt cups, 250 g margarine tubs, and 150 g cream cheese containers.

What Processing Window Prevents Warpage in Thin-Wall Closures for Still Beverages?

Thin-wall tamper-evident closures for still water and dry nutrition bottles have a part mass of 1.8–2.6 g and a wall thickness of 0.50–0.80 mm across the skirt and top panel. The lower melt-temperature limit for K4750 in this geometry is 185 °C, below which knit-line weakness at the tamper-evident bridge generates short shots; the upper limit is 240 °C, above which oxidative degradation increases the yellowness index and causes irregular melt viscosity. The high MFR of 50 g/10 min enables filling of 24-cavity cold-runner moulds at injection pressures of 90–130 MPa. Sub-gate diameters of 0.6–0.8 mm are used to balance shear heating and pressure drop; larger gates increase cycle time but do not improve knit-line strength because molecular orientation across the bridge is shear-limited.

For food and beverage use, the closure compound must conform to FDA 21 CFR 177.1520, EU 10/2011, and organoleptic methods such as EN 1622 for odour and flavour transfer. A typical stabilisation package contains 0.05–0.10 wt% hindered phenol primary antioxidant and 0.05–0.10 wt% phosphite processing stabiliser; slip agent is omitted when top-panel printing requires ink adhesion, otherwise 250–500 ppm erucamide may be included. Regrind levels are capped at 15 wt% because higher fractions of hot-runner and sprue regrind reduce notched impact strength of the tamper-evident band. The grade is not recommended for carbonated soft-drink closures above 2.5 volumes CO2, because environmental stress crack resistance under ASTM D1693 is lower than that of medium-melt-flow HDPE grades; for aggressive surfactant detergents or carbonated lines, a higher molecular weight HDPE should be specified.

Mould temperature is set at 18–25 °C; lower temperatures shorten cycle time but increase thermal stress at the knurl root. Holding pressure follows a two-stage decay profile from 70 MPa to 35 MPa over 0.8 s, with screw retraction timed to prevent backflow into the sprue. Cooling time of 3.5–5.0 s is sufficient for a 2 g closure, but demoulding before the top panel reaches 70 °C may increase ovality beyond 0.3 mm on a 30 mm diameter. Multi-cavity hot-runner valve gating is preferred to eliminate cold-sprue regrind and to maintain uniform melt delivery across 16 to 24 drops. Finished components include 30/25 mm screw caps for still water, 38 mm tamper-evident caps for dry nutrition powders, and 28 mm push-on caps for condiments.

Thin-Wall Housewares and Stackable Storage Bins

Stackable storage bins moulded from K4750 rely on a flexural modulus of approximately 1,050 MPa measured by ISO 178:2019 and a Shore D hardness of 64 per ISO 868:2003. The high melt-flow rate permits injection of ribbed sidewalls and snap-fit undercuts with wall thicknesses from 0.8 mm to 1.5 mm without visible sink marks when the rib-to-wall ratio is kept below 0.6:1.0. Tool compensation uses a shrinkage allowance of 1.5–2.0% in the flow direction and 2.0–2.5% transverse to flow, as determined by ISO 294-4:2018.

These articles are non-food contact; the relevant obligations are REACH Regulation 1907/2006 Article 33 communication for substances of very high concern above 0.1 wt%, and ASTM D4976 as a material specification for polyethylene moulding and extrusion. If the bin is marketed with toy or childcare features, EN 71-3:2019 migration limits for trace elements apply. A typical formulation uses 100% virgin K4750 with 0.03–0.08 wt% antioxidant masterbatch; antistatic additives are generally not used for indoor articles because they raise surface conductivity without meeting IEC 61340-5-1 packaging requirements.

Melt temperature is held between 200 °C and 220 °C; higher melt temperature improves gloss on the visible surface but increases gas trapping at the far end of deep ribs. Mould cooling circuits are set to 20–35 °C with a delta T of ±3 °C across the core and cavity. Screw forward time is 2.0–3.5 s, and holding pressure of 45–60 MPa is maintained until the gate freezes, indicated by a screw cushion of 3–5 mm. For an 8-cavity mould producing a 5 L bin, clamp force requirement is 5,000–7,000 kN at a projected cavity pressure of 35 MPa. Warpage at the lid interface is controlled by pre-cambering the long side wall by 1.0 mm over a 400 mm span. Components include 3–20 L stackable bins, under-bed storage trays, office literature sorters, and modular drawer units.

Critical Shrinkage Anisotropy Governs Dimensional Tolerances in Thin-Wall Pails for Water-Based Media

For thin-wall pails with a capacity of 2–10 L and a wall section of 1.0–1.5 mm, CREOLEX K4750 is processed at a melt temperature of 200–230 °C at the nozzle. Temperatures below 200 °C raise injection pressure beyond 110 MPa, while temperatures above 230 °C can generate gas bubbles at the confluence of the handle boss and the sidewall because the high-flow grade retains heat in thick intersections. Shrinkage anisotropy is the principal dimensional concern; the grade shows approximately 1.8% shrinkage in the flow direction and 2.4% transverse to flow under ISO 294-4:2018, so the mould must be cut with differential allowances across the pail bottom and the rim.

For water-based latex paints, the pail must comply with ASTM D4976 for the base polymer and with UN 1H2 plastics drum or jerrican standards only if the complete packaging passes drop and stack tests under UN 6.1.5.3; K4750 is usually limited to non-UN configurations unless the full packaging is certified. For food-carrying pails, the same food-contact conditions as dairy cups apply under FDA 21 CFR 177.1520(c) and EU 10/2011. If the paint formulation contains aggressive solvents, the pail grade must be upgraded to a higher molecular weight HDPE with ESCR above 24 h under ASTM D1693 condition B; K4750 is not recommended for aromatic or chlorinated solvent systems.

Injection moulding of a 5 L pail uses a screw with an L/D of 20:1–24:1, a back pressure of 6–10 MPa, and a shot size that maintains a cushion of 4–6 mm. Injection speed is profiled: 180–250 mm/s during rim filling reduces jetting at the handle boss, followed by 60–80 mm/s pressure-limited packing to avoid flash at the mould parting line. Mould temperature is 15–30 °C. Holding time is 4–8 s, and cooling time is 8–15 s depending on coolant temperature and wall thickness. Demoulding temperature below 75 °C at the rim prevents ovality exceeding 2 mm on a 240 mm inside diameter. Finished examples include 5 L water-based paint pails, 10 L wall-paint buckets, and 2 L industrial cleaning pails for non-oxidising aqueous formulations.

When cosmetic jar bases and overcaps are injection moulded from CREOLEX K4750, the melt temperature is held at 190–215 °C, and wall thickness is limited to 2.5 mm because the high MFR promotes internal cooling gradients that produce voids if holding pressure is insufficient. The grade is selected for jars that contact dry or anhydrous formulations, not for high-solvent nail lacquer or perfume-containing systems, because flavour and odour barrier properties are poor. Cosmetic packaging compliance requires the finished article to satisfy EU Regulation 1223/2009 Annex I for packaging compatibility; for the United States, the polymer must be a permitted food-contact substance under FDA 21 CFR or meet 21 CFR 174.5 general packaging requirements if the jar is not in direct contact with the skin. Typical formulation includes 0.05–0.10 wt% antioxidant and 0.03–0.08 wt% acid scavenger; white masterbatch at 2–4 wt% is common for opacity, but titanium dioxide loadings above 4 wt% increase melt pressure and reduce MFR in the cavity. Mould temperature is 20–35 °C, injection pressure 80–120 MPa, and holding pressure is divided into two stages: 50 MPa for 1.0 s then 30 MPa for 2.0 s. The result is a 50 mL cream jar base or a 30 mL overcap with a gloss surface. Published data for this specific configuration is limited; thermal residence time above 30 min at 210 °C should be avoided because the narrow processing window of high-flow HDPE can lead to viscosity reduction and dimensional drift.

When Multi-Cavity Moulds for Garment Hangers Demand Melt Flow Above 45 g/10 min

Producing garment hangers with a tubular profile and a wall section of 1.5–2.5 mm requires shear rates below the critical molecular orientation threshold of 40,000 s⁻¹ at the gate; K4750 with an MFR of 50 g/10 min meets this requirement in 12-cavity moulds at melt temperatures of 190–220 °C. The long flow path from the central sprue to the hook and arm ends exceeds 300 mm, and hesitation at the hook can create a visible flow mark if the injection speed is below 150 mm/s during the first 0.3 s of fill. Gate diameter is set at 1.0–1.2 mm to balance filling pressure and stringing at the hot tip.

For export to the EU, hangers for textile retail are unplasticised so phthalate restrictions under REACH Annex XVII entry 51 do not apply, but the producer must still maintain documentation for substances of very high concern under Article 33 if any additive package changes. Formulation is normally 100% virgin K4750 with 0.03–0.06 wt% processing antioxidant; colour masterbatch is added at 1–3 wt% for retail hangers, and the carrier resin must be HDPE-compatible to avoid delamination at the hook. Mould temperature is 15–25 °C; holding pressure of 40–55 MPa is maintained until the gate freezes, and cooling time of 8–12 s is typical for a hanger mass of 35–45 g. Finished products include tubular hangers, clip hangers for trousers, and swivel-hook hangers for multi-pack displays.