PetroChina Daqing HDPE 5300B is a high-density polyethylene blow-moulding grade produced by Daqing Petrochemical Company. The resin is supplied as pellets and is intended for extrusion blow moulding of monolayer containers, overlapped and flash-trimmed bottles, jerrycans, and small industrial drums. In general terms, the grade is characterised by a melt flow rate of 0.30–0.40 g/10 min measured at 190 °C under a 2.16 kg load in accordance with ISO 1133-1:2022, and a density of 0.952–0.955 g/cm³ determined by ISO 1183-1:2019. These values identify a low-melt-flow, high-density polyethylene with sufficient melt strength for parison formation but lower fluidity than conventional injection-moulding grades. Common conversion lines include continuous shuttle blow-moulding machines and accumulator-head extrusion blow-moulding machines equipped with grooved-barrel extruders, where the resin is processed through a converging die to produce a hanging parison that is captured and inflated inside a cooled mould. 5300B is not normally recommended for high-speed thin-wall injection moulding, blown film, or extrusion coating because the low melt flow rate can increase injection pressure, reduce drawdown stability, or alter coating line speed relative to grades formulated specifically for those processes. The commercial grade designation 5300B does not encode density or melt flow rate; it identifies the product position within the Daqing HDPE portfolio, and the trailing letter indicates a blow-moulding application class. Because comonomer type, antioxidant loading, and catalyst residue are not fixed solely by grade number, processors should obtain and retain a certificate of analysis for each lot and confirm that the values fall within the intended processing window. The manufacturer’s technical documentation typically reports the above ranges, but published data for highly specific mould configurations or long-term performance under unusual chemical environments is limited.

How Does 5300B Differ from High-Flow Injection-Moulding HDPE?

High-flow injection-moulding HDPE grades commonly exhibit melt flow rates of 4–12 g/10 min under ISO 1133-1:2022, in contrast to 0.30–0.40 g/10 min for 5300B. This rheological difference is the primary reason 5300B should not be used in an unmodified injection-moulding cavity designed for high-flow HDPE. In injection moulding, a low-MFR resin demands higher filling pressure, generates greater shear heating at the gate, and can produce flow marks or short shots in thin-walled sections below 1 mm. Injection grades are often run at melt temperatures of 200–260 °C with fast injection profiles to reduce viscosity, whereas blow moulding with 5300B relies on a lower melt temperature, typically 190–205 °C, to preserve parison melt strength. The same low-MFR character that restricts injection flow provides blow-moulding advantages: the hanging parison exhibits less gravitational sag, more uniform wall thickness over long head-to-mould distances, and improved retention of die swell. Capillary rheometry under ISO 11443:2021 can be used to compare the apparent viscosity of the two grades; the 5300B material will normally show a higher viscosity across the extruder shear-rate range from 100 s⁻¹ to 500 s⁻¹. Because product-specific flow curves are not always supplied, processors should commission capillary rheometry when changing from an existing HDPE grade or when designing an accumulator-head tool with tight parison weight control.

Melt Flow Rate, Density, and Tensile Property Ranges

Typical values reported for 5300B are summarised below. These values should be read as commercial technical data rather than a specification unless they appear on the supplier certificate of analysis. The melt flow rate and density are the two critical incoming inspection parameters because they directly affect parison sag and bottle weight.

Density at 0.952–0.955 g/cm³ contributes to container stiffness and chemical resistance, while the tensile yield stress of 24–27 MPa and flexural modulus of 1000–1200 MPa support top-load performance in filled bottles. The tensile property values are generally measured on compression-moulded specimens prepared according to ISO 293:2004 or injection-moulded specimens prepared according to ISO 294-1:2017; differences in specimen preparation can produce small but measurable shifts in yield stress. Environmental stress cracking resistance under ASTM D1693-15 is reported above 100 h in 100% Igepal CO-630 at 50 °C, which is relevant for containers holding detergents, surfactants, or aqueous organic mixtures. The Vicat softening temperature of 122–126 °C under ISO 306:2022 method A50 indicates that the grade is not intended for hot-fill applications above 80 °C without a separate softening and migration study. Melt flow rate remains the most sensitive indicator of lot-to-lot variation; a shift from 0.30 g/10 min to 0.40 g/10 min may reduce parison hang-time and require die gap adjustment on an accumulator-head machine.

On continuous shuttle and accumulator-type extrusion blow-moulding lines, the screw temperature profile is commonly ramped from 170 °C in the feed zone to 200 °C in the metering section, with head and die temperatures held at 190–205 °C. Grooved-barrel extruders with L/D ratios of 24:1–30:1 are preferred because the grooved feed section delivers stable throughput against the high pressure generated by the converging die. Mould temperatures from 10 °C to 30 °C and blow air pressures of 0.55–0.75 MPa are typical for high-density polyethylene blow moulding; excessive blow pressure does not compensate for insufficient parison inflation and can create flash at the parting line. Cycle time is controlled primarily by wall thickness, mould temperature, and cooling air flow, not by melt temperature alone. A common field failure on accumulator-head machines is parison curling caused by uneven die temperature or damaged die bushings; the melt strength of 5300B does not mask mechanical misalignment. Pellets stored below ambient temperature should be conditioned before processing because surface condensation above 0.05% can generate bubble defects and splay. Drying at 70–80 °C for 1–2 h is used only when condensation is observed; routine drying of dry HDPE is unnecessary.

When Food-Contact Conformity Demands Low Extractable Content

Food-contact and pharmaceutical containers produced from 5300B require end-article compliance, not solely resin compliance. The base resin is represented as suitable for food-contact use under FDA 21 CFR 177.1520, EU Regulation (EU) No 10/2011, and China GB 4806.7-2016 when processed within the recommended temperature range and with suitable masterbatches. Overall migration testing under EU Regulation (EU) No 10/2011 should meet the 10 mg/dm² limit for the intended food simulant, but the final moulded article must be tested because extrusion temperature, regrind ratio, and cooling rate can affect extractables. The resin’s antioxidant and catalyst neutralisation package is selected for low odour and low colour, but pigment masterbatches, external lubricants, and non-compliant regrind can invalidate conformity. For pharmaceutical closures, additional testing under USP <661.1> or Ph. Eur. 3.1.3 may be required depending on the target market. The grade is not recommended for continuous service above 80 °C without oxidative stability data, and it is not intended for retort or repeated steam sterilisation. In applications where the container is exposed to aggressive solvents, the environmental stress cracking resistance should be re-tested under the actual chemical environment because ESCR values from ASTM D1693-15 are not a direct predictor of field failure for all liquid classes.

Regrind from clean 5300B bottles is routinely added back into blow-moulding processes at mass fractions of 20–30%; higher regrind fractions reduce melt pressure stability and increase the risk of black specks, gel contamination, and odour. The regrind must be free of labels, caps made from other resins, and adhesive residues, because polypropylene or paper contamination can form visible inclusions in the parison wall. Mixing regrind from different HDPE grades is not recommended unless the melt flow rate of the blend is re-checked under ISO 1133-1:2022, and the density is re-checked under ISO 1183-1:2019. When food-contact conformity is required, the regrind source must be controlled and documented under the same hygiene discipline as virgin pellets. A shift in regrind particle size distribution can also alter bulk density and feeding stability in the grooved-barrel extruder, producing surging at the die and variable bottle weight. Processors should maintain regrind ratio within a defined control range and monitor parison length by die-cut weight or machine vision to detect drift before wall-thickness failures occur.

Cycle Time and Parison Sag Are Governed by Melt Strength

Within the Daqing HDPE portfolio, 5300B is positioned as a low-MFR blow-moulding grade, distinct from grades intended for blown film, monofilament, or injection moulding. Compared with higher-MFR HDPE grades of similar density, 5300B provides reduced parison sag and improved wall-thickness uniformity in deep-draw containers, but the same property extends ejection cooling because the thicker parison in the flash and pinch-off zones conducts heat more slowly. On accumulator-head machines, die gaps from 0.8 mm to 2.5 mm are used depending on container size and parison weight; parison swell varies with die geometry, output rate, and melt temperature, and published data for a specific mould configuration is limited. A processor should therefore perform an on-site mould trial rather than rely solely on melt flow rate and density. Differences from other products should not be inferred from density and MFR alone. A grade with identical MFR but narrower molecular weight distribution may exhibit less die swell and lower melt strength, while a grade with higher comonomer content may show greater environmental stress cracking resistance but lower top load. Selection of 5300B is justified when the container design demands a balance between stiffness, ESCR, and parison stability. The grade is not recommended for combination with peroxide masterbatches or strong oxidising additives unless the melt flow rate and colour are re-tested; such additives can shift the molecular weight distribution and reduce impact performance of the moulded article.