Lotte Chemical ABS HC-1110, identified by the Starex grade nomenclature, is an acrylonitrile-butadiene-styrene copolymer formulated for high-flow injection moulding of thin-section technical components. The material comprises a continuous styrene-acrylonitrile phase and dispersed grafted polybutadiene rubber inclusions, a morphology that provides the characteristic ABS balance of rigidity, surface hardness and impact resistance. Supplier technical literature lists a melt mass-flow rate of 11.0 g/10 min at 220 °C under a 10.0 kg load in accordance with ASTM D1238 and a density of 1.04 g/cm³ in accordance with ASTM D792. The grade is supplied as natural pellets and is intended for opaque injection-moulded parts where filling pressure, cycle time and dimensional stability of thin-wall sections control the manufacturing economics. Representative application categories include small appliance housings, vacuum cleaner components, office automation covers and consumer electronics shells for which wall stock is commonly 1.5 mm to 3.0 mm.

What Distinguishes HC-1110 Within the Lotte Chemical Starex ABS Portfolio?

The grade occupies the high-flow segment of the manufacturer’s ABS line. Its melt mass-flow rate of 11.0 g/10 min under 220 °C/10.0 kg separates it from lower-flow moulding grades and from extrusion grades that require higher melt strength for sheet or profile stability. The flow advantage is achieved without moving into the low-viscosity, low-molecular-weight region that can compromise notched Izod impact; the reported 23 °C notched Izod value is 22.0 kJ/m² by ASTM D256. The difference from plateable ABS grades is structural: HC-1110 is not optimised for acid etching and electroplating adhesion, whereas the rubber particle-size distribution and styrene-acrylonitrile interfacial chemistry in plateable grades are adjusted for metal adhesion. The difference from heat-resistant ABS lies in thermal capability; HC-1110 carries a Vicat softening temperature of 96.0 °C by ASTM D1525 and a heat deflection temperature of 88.0 °C at 1.82 MPa by ASTM D648, placing it in conventional, non-heat-stabilised ABS territory.

Representative mechanical values are conditioned at 23 °C and 50% relative humidity unless otherwise stated. Actual lot values may vary within the supplier’s specification window, particularly after regrind addition or colour masterbatch dilution.

Rheological characterisation of HC-1110 in supplier public literature is typically limited to the single-point ASTM D1238 melt mass-flow rate value. A complete capillary viscosity curve as a function of shear rate, temperature and pressure is not published in the standard datasheet; processors requiring gate shear-rate calculations should request a multi-point viscosity curve from the compounder or run capillary rheometry on dried pellets. On production equipment, the practical effect of the 11.0 g/10 min flow is observed as lower peak cavity pressure during filling of thin-wall parts below 2.5 mm wall stock. In a typical hydraulic injection moulding machine with a 40 mm diameter reciprocating screw, shot volume and clamp force demand for a given component are reduced relative to a lower-flow grade of similar density; however, the exact reduction is tool-dependent and should be confirmed by cavity pressure transducers rather than inferred solely from the single-point flow value.

Injection moulding process conditions recommended in supplier literature are a melt temperature of 200–240 °C and a mould wall temperature of 40–80 °C. The lower melt-temperature limit corresponds to high screw torque and reduced flow length; the upper limit is set by polybutadiene gel formation and yellowing. A rear-to-nozzle barrel profile of 200/220/230/220 °C is commonly used for general-purpose ABS in reciprocating screw machines, but actual settings must be adjusted for screw L/D ratio, residence time and check-ring design. Back pressure should be kept at 0.5–1.0 MPa hydraulic equivalent to avoid excessive shear heating during screw recovery. Screw surface speed should be set to 0.1–0.3 m/s; higher speeds in large-diameter screws add frictional heat to the melt and can move the actual melt temperature above the set barrel temperature.

When Shear Heating Exceeds the Critical Threshold in Thin-Wall Moulds

In moulds with wall thickness below 2.0 mm, filling times are shortened by increasing injection velocity; however, the shear heating associated with high-velocity flow through restrictive gates can raise the local melt-front temperature above the barrel setpoint. If the local melt exceeds 240 °C, degradation products from the polybutadiene phase can appear as brown streaks or gloss differences in the gate region. Published data for the exact shear-heating threshold of HC-1110 under commercial tooling is limited; the condition is governed by gate shear rate, gate diameter, runner geometry and melt compressibility. Mould trials should instrument the tool with cavity pressure transducers and thermocouples to correlate peak cavity pressure with gate freeze time. A conventional optimisation sequence is to increase injection velocity until short shots disappear, then reduce velocity by 10–15% to maintain a margin against jetting and shear-induced splay. For hot-runner systems, manifold and nozzle dwell time must be kept below the cumulative residence-time limit; hot-runner dead spots are a known source of black specks in white or tinted ABS parts.

Mechanical behaviour of HC-1110 is anisotropic in injection-moulded parts because of flow-induced orientation of the grafted rubber phase and styrene-acrylonitrile matrix. The supplier-reported mould shrinkage range of 0.4–0.7% according to ASTM D955 indicates that local shrinkage variation across a part can approach 0.3% absolute. For enclosures requiring tight sealing surfaces, gate location must be positioned to avoid asymmetric packing; flow-leading and flow-lagging regions can produce differential shrinkage and warp. Weld-line flexural strength is typically below the bulk value for unreinforced ABS, although published HC-1110-specific weld-line data is limited. If a part design places a weld line in a snap-fit or screw boss, a short-shot flow study and instrumented drop test should be used to validate knit-line fusion quality.

Predrying Requirements and Moisture Uptake in Humid Transfer Lines

ABS HC-1110 must be dried before processing when exposure to ambient air exceeds 30 min in relative humidity above 60%. The recommended drying condition is 80 °C for 2–4 h in a desiccant dryer with a dew point of −40 °C or lower, producing residual moisture below 0.05%. Moisture levels above 0.10% can generate splay streaks, silver marks and premature gate blush on the moulded surface. In high-humidity transfer lines, pellets should be conveyed in closed dry-air lines; open pneumatic conveying with plant air is a documented source of batch-to-batch moisture variation. Prolonged hot-air exposure at the upper drying limit can cause yellowing; dryer residence time should not exceed 8 h.

Outdoor UV exposure causes photodegradation of the polybutadiene phase in ABS. HC-1110 is not supplied with a UV-stabiliser package as standard, and direct sunlight or UV-C sterilisation exposure requires a UV-stabilised grade or an external coating. Gloss retention and colour shift should be evaluated under ASTM D4459 or ISO 4892-2 if the part is specified for outdoor use. Chemical resistance is acceptable for dilute acids and bases, but the grade is attacked by ketones, esters, chlorinated solvents and aromatic hydrocarbons. Stress cracking can occur in the presence of certain alcohols and plasticising oils; chemical exposure should be validated using ASTM D543 immersion or strain-bend procedures.

Flammability and chemical compliance are application-dependent. The grade is reported as UL 94 HB at 3.0 mm; it is not flame-retardant ABS and must not be substituted into enclosures requiring V-2, V-1 or V-0 ratings. Supplier declarations for RoHS recast and REACH SVHC should be requested by lot because pigment masterbatches and processing aids can alter the final article status. The unfilled grade does not contain halogenated flame retardants, per the supplier’s standard documentation, but downstream formulations must be re-evaluated under IEC 62321-1 protocols. For food-contact or medical use, no USP Class VI or FDA 21 CFR compliance is assigned to the standard grade; users requiring these statuses must select a dedicated grade.

Incoming inspection of HC-1110 should include at minimum melt mass-flow rate, notched Izod impact and density. Batch-to-batch MFR variation in high-flow ABS can shift filling behaviour even when all measured values are within specification; processors are advised to trend these values using statistical process control. The material should be purged with a low-MFR ABS or acrylic-based purging compound at colour or grade changes; purging with polyolefin-based materials is not recommended because of degradation residues and contamination in hot-runner systems.