In returnable logistics crate production, Sinopec Zhenhai HDPE 7260 is processed as a high-flow injection-moulding feedstock with a nominal melt flow rate of 6.0 g/10 min under ISO 1133-1:2022 at 190°C/2.16 kg and a density of 0.956 g/cm³ under ISO 1183-1:2019. The compound is dry-blended at 97.0 wt% virgin 7260, 2.5 wt% carbon black masterbatch carrying 40% carbon black, and 0.5 wt% hindered phenolic antioxidant masterbatch. Melt temperature is controlled at 200°C to 230°C. The mould wall is held at 10°C to 25°C; sustained wall temperatures above 35°C extend cooling time without measurable improvement in drop impact. Injection speed is profiled from 40 mm/s to 110 mm/s. Clamp force is calculated from a projected-area multiplier of 3.0 kN/cm² to 4.0 kN/cm² on a 650-tonne hydraulic press using a 22:1 L/D general-purpose screw and hot-runner valve gates. Lot-to-lot MFI variation of ±0.5 g/10 min requires packing-pressure compensation of 5 MPa to 10 MPa to hold part mass within ±0.5%. Mechanical verification follows ISO 527-2 at 23°C and 50 mm/min for tensile yield and ISO 178 for flexural modulus. Drop impact at -20°C is tested under ISO 6603-2; published data for this specific 7260 configuration are limited, but converter validation commonly targets non-brittle failure on a 2.0 mm plaque. Terminal parts include stackable dairy crates, returnable agricultural totes, and industrial distribution boxes with anti-slip base inserts.

Which mould-filling defects control reject rates in 7260 thin-wall deli containers?

Thin-wall delicatessen containers moulded from Sinopec Zhenhai HDPE 7260 are limited by gate blush and jetting when acceleration exceeds 120 mm/s at a gate diameter below 0.8 mm. The food-contact formulation is compounded at 99.2 wt% 7260 with 0.8 wt% sodium benzoate nucleating masterbatch. The nucleating additive reduces cycle-time-dependent post-mould shrinkage and improves top-load stiffness under ISO 604, but it also narrows the processing window. Melt temperature is maintained at 220°C to 240°C. Mould temperature is set at 15°C to 30°C. Packing pressure is held at 40 MPa to 50 MPa for 0.8 s to 1.5 s on wall sections of 0.8 mm to 1.2 mm. After 48 h conditioning at 23°C under ISO 294-4, post-mould shrinkage is measured at 1.2% to 1.8% in flow direction and 1.6% to 2.2% transverse to flow. Food-contact compliance is evaluated under FDA 21 CFR 177.1520 and EU 10/2011; the grade itself does not automatically confer approval, and overall migration of the finished part must be verified below 10 mg/dm² under EN 1186-1. Terminal parts include 500 mL to 1000 mL refrigerator-stable deli containers and matching overcap lids.

Non-carbonated screw-cap production uses Sinopec Zhenhai HDPE 7260 at 95.0 wt% with 3.0 wt% white masterbatch containing 60% titanium dioxide and 2.0 wt% slip masterbatch containing 5% erucamide in LLDPE. The compound is gravimetrically fed at the feed throat. Pre-drying is not required when sealed silo storage remains below 60% relative humidity; if surface condensation is detected, a hopper dryer at 70°C for 1.5 h is applied. Melt temperature is held at 230°C ± 5°C to prevent erucamide decomposition and off-odour generation. The moulding operation uses injection-compression stroke control with a mould temperature of 15°C to 20°C. Post-mould ovality after 24 h at 23°C under ISO 294-4 is controlled below 0.3 mm on a 38 mm closure diameter. Closure seal integrity is verified by a positive-air pressure decay test at 20 kPa for 10 s. Direct and indirect food-contact compliance follows FDA 21 CFR 177.1520 and EU 10/2011. Terminal parts include non-carbonated beverage caps, personal care flip-top closures, and edible oil lids, excluding carbonated beverage applications because the grade lacks sufficient stress-crack resistance and sealing force retention under sustained carbonation pressure cycling.

Stackable 20-litre open-top pail bodies in 7260 injection moulding

For non-hazardous chemical and paint pails, Sinopec Zhenhai HDPE 7260 is compounded at 84.5 wt% virgin resin, 12.0 wt% post-consumer HDPE recyclate with an MFI of 0.3 g/10 min to 0.8 g/10 min, 3.0 wt% colour concentrate, and 0.5 wt% LLDPE toughening additive. Recyclate addition drops the combined melt flow rate to approximately 3.2 g/10 min, requiring a melt temperature rise to 240°C to maintain knit-line strength at the handle ears. Mould temperature is set at 10°C to 30°C. Packing pressure is maintained at 60 MPa to 80 MPa for 6 s to 10 s to eliminate sink marks around the ribbed base. Drop impact for 20 L pails intended for dangerous goods is assessed under UN 1H2 open-head plastics container requirements, with conditioning at -18°C for 48 h and a drop height of 1.8 m. Environmental stress crack resistance is measured under ASTM D1693-15 Method B in 10% Igepal CO-630 at 50°C; if the 12 wt% recyclate blend falls below 24 h, the LLDPE fraction is increased to 1.0 wt% and verification is repeated. The compound is not recommended for prolonged oxidising chemical storage above 50°C because oxidative embrittlement may occur. Terminal parts include paint pails, detergent pails, and non-hazardous chemical buckets with tamper-evident lids.

When a high-flow HDPE is specified for automotive washer reservoirs

When Sinopec Zhenhai HDPE 7260 is used for automotive washer reservoirs, the compound is prepared at 97.0 wt% 7260 and 3.0 wt% carbon black masterbatch with 40% carbon black loading. The part is injection moulded at a melt temperature of 220°C to 240°C and a mould temperature of 15°C to 30°C. The filler neck and mounting bosses create knit lines; weld-line tensile retention is evaluated by cutting specimens parallel and perpendicular to flow from an injection-moulded plaque and testing under ISO 527-2 at 23°C and 50 mm/min. Retention below 60% of virgin yield is cause for rejection. Long-term thermal ageing is assessed under ISO 188 at 85°C for 1000 h; published data for this specific grade configuration are limited, but the resin should be restricted to washer reservoirs and exterior cold-fluid containers, not under-bonnet coolant expansion tanks exceeding 80°C or pressurised fuel-containing components. Pre-drying is required when exposure to relative humidity above 60% has occurred; a 70°C forced-air hopper dryer for 1.5 h is used before processing. Terminal parts include headlamp washer reserve tanks and windshield washer reservoirs.

Household stackable storage boxes and toy bins are moulded from 100 wt% Sinopec Zhenhai HDPE 7260 or from 98.0 wt% 7260 with 2.0 wt% colour masterbatch. Melt temperature is kept at 190°C to 220°C. The mould wall is controlled at 10°C to 20°C. Cycle time on a 350-tonne press is set by the cooling phase; reducing wall thickness below 1.5 mm requires raising melt temperature to 230°C to avoid short shots, but this increases post-mould shrinkage under ISO 294-4 above 2.0%. Colour concentrates must comply with EU 10/2011 and REACH for use in children’s articles; if the finished bin is intended for toy storage, heavy-metal release is checked under EN 71-3. Terminal parts include under-bed storage boxes, stackable toy bins, and general household utility crates.