LG Chem ABS HF-380L is an injection-moulding grade of acrylonitrile-butadiene-styrene terpolymer whose designation places it among high-flow ABS resins for thin-wall and long-flow-path moulding. Supplier-published typical values for natural grade include density of 1.05 g/cm³ under ISO 1183-1:2019, melt mass-flow rate of 38 g/10 min at 220 °C under 10 kg load per ISO 1133-1:2022, tensile yield stress of 44 MPa under ISO 527-2:2012, flexural modulus of 2.3 GPa under ISO 178:2019, notched Izod impact of 16 kJ/m² at 23 °C under ISO 180/A:2023, and deflection temperature under load of 84 °C at 1.8 MPa under ISO 75-2/Af. Certificate of analysis values for coloured or compounded lots may shift with pigment concentration and moulding conditions; the listed data are not absolute specification limits.

What Distinguishes a High-Flow ABS Grade from Medium-Flow Injection Moulding Resins?

The principal difference is rheological. Medium-flow ABS grades typically require higher fill pressure in thin-wall tools, produce longer injection time at the same wall thickness, and may exhibit short-shot defects when the flow path exceeds 300 mm to 500 mm depending on gate size. LG Chem’s general-purpose ABS grades, such as HI-121H, are commonly reported with a melt mass-flow rate near 18 g/10 min under equivalent conditions, so HF-380L provides approximately double the melt-flow index. That increase in flow is obtained through molecular and morphology control; the effect is a measurable retreat in notched Izod impact and heat-deflection temperature relative to medium-flow grades at the same wall thickness.

At equivalent wall thickness, the high-flow grade sacrifices some impact resistance and heat tolerance. The reduction is not large enough to exclude the grade from structural components, but it shifts design limits for snap-fits, self-tapping screw bosses, and clip arm deflections. Weld-line strength can also be lower when melt fronts meet after passing around long core pins, because the lower melt viscosity does not always maintain sufficient front temperature. Published data for this specific configuration is limited; tool trials should establish weld-line factor values for the final part drawing.

Injection moulding trials on reciprocating-screw machines with a three-zone general-purpose screw are used to establish the processing corridor for HF-380L. Desiccant drying at 80 °C to 90 °C for 2 h to 4 h is required when ambient relative humidity exceeds 60 %; incoming air with a dew point below -30 °C and residual moisture below 0.05 wt% are common targets before plastication. Barrel zone temperatures from feed to nozzle are typically set between 190 °C and 240 °C, with melt temperature measured by air shot not exceeding 240 °C. Mould temperature is usually held between 30 °C and 60 °C. For thin-wall sections below 1.5 mm, injection pressure can reach 70 MPa to 110 MPa; hold pressure is generally 50 % to 70 % of the observed fill pressure.

Screw recovery is not usually the cycle limiter for a high-flow grade, but back pressure between 0.5 MPa and 1.5 MPa is applied to homogenise the melt. A screw with L/D 20:1 to 24:1 and compression ratio 2.0:1 to 2.5:1 is adequate for most general-purpose machines. Parting-line vent channels with depth 0.02 mm to 0.05 mm are normally maintained. Surface splay, silver streaks, or brown discoloration at the hot sprue usually indicate moisture or local degradation; flow-front burn marks suggest inadequate venting or gas trapping; gate blush from excessively high shear may require reduced injection velocity or larger gate dimensions.

Residual Moisture, Vent Depth, and Screw Recovery Parameters.

Moisture sensitivity in HF-380L is not as severe as in polycarbonate or polyamide, but inadequate drying remains a common source of surface defects because the polybutadiene phase can oxidise at plastication temperatures. Hot-runner systems should limit manifold temperature to no more than 10 °C above the melt setpoint; higher thermal stress can generate decomposition gases and visible yellowing. Valve-gated drops are preferred where gate sealing is necessary because the high-flow front may otherwise drool through open hot sprues during part extraction.

Regrind use in production-scale moulding is commonly limited to 20 % by weight until the moulder verifies that melt-flow shift and impact retention remain within the part specification. Multiple heat histories can raise the melt-flow rate and reduce notched impact; the exact shift depends on drying temperature, residence time, and colourant system. If a tool is converted from a medium-flow ABS to HF-380L, the moulder should verify that the reduced melt viscosity does not increase flash formation at parting-line clearances above 0.03 mm and should re-establish the hold-pressure gate-seal time.

For enclosure applications governed by IEC 62368-1, HF-380L can be considered for non-fire enclosure parts, internal brackets, and decorative surfaces where the appliance or information technology equipment specification does not impose a V-0 or V-1 flammability requirement. In products assessed under IEC 60335-1 for unattended appliances, the UL 94 HB classification may not pass glow-wire ignition or flame-spread clauses for parts in contact with uninsulated live components; a flame-retardant ABS or PC/ABS is normally required in these positions.

Supplier literature identifies the grade for thin-wall electrical connectors, appliance housings, computer peripheral components, and automotive interior parts. Because the melt-flow classification may permit filling of wall thicknesses below 1.5 mm, the grade is often evaluated for injection-moulded housings where fill pressure and cycle time dominate part cost. However, published data for this specific configuration is limited, and end-use tool trials must confirm that gloss, colour, flow, and impact meet drawing requirements. Chemical resistance follows ABS architecture: the material is not suitable for continuous contact with ketones, esters, chlorinated solvents, or concentrated oxidising acids. Stress-cracking agents in after-market cleaning products can cause environmental stress cracking in moulded-in-stress regions.

When UL 94 HB Does Not Satisfy IEC 62368-1 Fire Enclosure Requirements.

Because HF-380L is rated UL 94 HB, it is not generally appropriate for fire-enclosure barriers or live-part retainers in products requiring V-0. The flammability classification is thickness-dependent and colour-dependent; a natural grade at 1.6 mm may differ from a black or white mass-pigmented lot. When a final part must satisfy IEC 62368-1, glow-wire flammability tests at end-use thickness are required, and the material alone cannot be certified to comply. Avoid prolonged processing with copper-containing masterbatch; catalytic degradation can lead to brown streaks. Polycarbonate contamination should also be controlled if ABS-only regrind streams are required, because PC/ABS blends alter heat resistance and chemical resistance even at low concentrations.

At the production scale, batch-to-batch variation in melt-flow rate and pellet geometry should be monitored from the certificate of analysis. Drying-time deviations and repeated regrind addition alter the flow-to-impact balance more than the original property table would suggest. If a tool is converted from a medium-flow ABS to HF-380L, the moulder should verify that the reduced melt viscosity does not increase flash formation and should re-establish the hold-pressure gate-seal time. For food-contact, medical-grade, or high-voltage live-part enclosures, independent regulatory assessment on the final part is required because the standard grade is not positioned for those end-uses.