Lotte Chemical ABS HI-1000 is a high-impact acrylonitrile-butadiene-styrene injection moulding grade in which the polybutadiene phase is dispersed at a concentration and particle-size distribution that shifts room-temperature notched Izod toughness above that of standard medium-impact ABS grades while retaining a useful balance of flow and rigidity. The grade is supplied as natural or pre-coloured pellets; typical industrial applications include vacuum cleaner housings, electroplated knobs, office automation covers, motor housings for hand-held tools, and consumer durables where the part must withstand occasional drop impact. Published single-point data derived from dried specimens are given in the table below.

The single-point values are from conditioned specimens and may shift by ±10 % depending on pigment loading, regrind content, and moulding parameters. They are not design allowables; safety factors must be derived from end-use temperature, strain rate, and chemical exposure under ISO 527-2 and ISO 178.

What Pre-Drying Parameters Minimise Splay and Melt Degradation?

Hydrolytic degradation of the SAN matrix during melt processing is a primary cause of splay, gate blush, and loss of notched Izod in HI-1000. The pellets absorb moisture from the atmosphere; if processed above 0.05 % moisture, the trapped water vapour produces visible splay on the moulded surface and reduces molecular weight at the barrel wall. The material should be dried in a dehumidifying or desiccant hopper dryer at 80 °C to 85 °C for 3 h to 4 h, with a supply air dew point below -40 °C. When ambient relative humidity exceeds 60 %, the residence time in the hopper should be extended to 4 h or the drying temperature raised within the published upper limit. Dried pellets should not stand in open containers for more than 30 min during shift breaks.

During injection moulding on a conventional hydraulic machine with a general-purpose screw of 20:1 to 22:1 L/D, the optimum melt temperature measured at the nozzle is 190–230 °C. Mould temperatures of 40–70 °C are used for opaque parts; values near the upper end of this range improve knit-line strength and reduce moulded-in stress but increase cooling time. Injection pressure required to fill a 2 mm wall part with a tunnel gate is typically 70–120 MPa. Back pressure should be held at 0.5–1.5 MPa and screw peripheral speed limited to 0.3–0.6 m/s to avoid rubber-particle chain scission. Cushion should be maintained at 3–6 mm. At 230 °C, total melt residence time should not exceed 5 min; longer residence times produce free-radical oxidation, yellowing, and a measurable decline in notched Izod. Moulds with hot runners should use open-pipe nozzles and polished channels; dead spots at shut-off nozzles cause black specks in surface-critical parts.

If Regrind Ratios Exceed 20 wt%

If regrind is reintroduced into the feed stream at a ratio above 20 wt%, the concentration of oxidised surfaces and reduced molecular weight species rises enough to alter flow length, colour, and impact resistance. Post-industrial regrind from HI-1000 sprues and runners should be granulated to uniform pellet size, passed through a magnetic separator, and dried at the same schedule as virgin pellets. For opaque parts not classified under flammability standards, 20 wt% regrind is generally accepted; for electroplating and high-gloss appearance parts, regrind should be limited to 10 wt% or eliminated because butadiene oxidation changes etch topography and plate adhesion. Published data for the specific peel-strength loss after multiple heat cycles are limited; qualification under ASTM B533 is required for each regrind ratio.

Across the application scope, HI-1000 fills a processing niche between low-viscosity high-flow ABS grades and high-heat ABS. High-flow ABS grades having a melt mass-flow rate above 20 g/10 min allow shorter cycle times in thin-wall multi-cavity tools but exhibit notched Izod values typically 10–15 kg·cm/cm and lower weld-line tensile strength. HI-1000, with its nominal MFR of 5 g/10 min, requires higher injection pressure and more generous gate dimensions; in exchange, the notched Izod at 23 °C is on the order of 45 kg·cm/cm for a 3.18 mm specimen. Compared with a heat-resistant ABS grade that increases the HDT beyond 100 °C, HI-1000 has a lower continuous-use temperature ceiling, typically unsuitable for components in contact with metal surfaces above 85 °C. Compared with flame-retardant ABS grades carrying a UL 94 V-0 rating, HI-1000 is classified UL 94 HB; it should not be used where electrical insulation requirements include glow-wire ignition under IEC 60695-2-11 without additional design barriers. Unlike glass-reinforced ABS, HI-1000 does not contain fibre and is therefore suited to electroplating and painting; unlike PC/ABS, it has lower heat distortion and lower notched Izod at -30 °C. The choice of HI-1000 over a high-gloss ABS grade involves a trade-off in surface gloss; high-gloss grades may use lower rubber content and higher flow for mirror-like surfaces, whereas HI-1000 is usually specified for structural housings where impact resistance outweighs critical gloss.

Melt Rheology and Gate Freeze Behaviour in Multi-Cavity Tools

The gate freeze time and pressure drop across multi-cavity runners control the lower limit of wall thickness. ABS of this viscosity class is shear thinning; capillary viscometry under ISO 11443 at 230 °C shows a sharp reduction in apparent viscosity as wall shear rate increases from 100 s^-1 to 1,000 s^-1. In the gate region, wall shear rate exceeds 10⁴ s^-1, allowing short cones to fill despite low screw rotation speed. If gate diameter is below 0.8 mm, premature gate freeze limits pack pressure transmission and produces sink marks; for a 2 mm wall, a gate land of 0.5–1.0 mm and a gate diameter of 1.0–1.5 mm are preferred. On a 16-cavity tool with geometrically balanced runners, cavity-to-cavity fill imbalance of 2–5 % is common from melt-temperature differences after the runner split. Pack pressure should be set at 50–70 % of injection pressure and held until the gate seals; gate seal time can be verified by weighing sequential short shots or by pressure-transducer decay at the post-gate cavity sensor. Published data for HI-1000 gate-freeze time across specific wall thickness configurations are limited; these values are operational starting points derived from general ABS processing practice.

For electroplating operations on HI-1000, the adhesion level is influenced by the etchant accessibility of the grafted polybutadiene domain. A typical preplate etch uses chromic acid at 60–70 °C for 10–20 min, followed by neutralisation and electroless nickel or copper deposition. The higher rubber content that gives HI-1000 its impact strength also increases micro-roughness after etching, which can improve mechanical interlocking but raises the risk of white-spot defects if moulded-in stress is excessive at the surface. Moulders should avoid high pack pressure near gates and use melt temperature at the lower end of the recommended window for electroplatable parts. Peel strength measured by ASTM B533 should be verified for each colour concentrate, because pigments can alter the oxidation state of the rubber phase and reduce adhesion.

In drop-impact tests on moulded housings, the limiting failure site is often not the flat panel but the weld line opposite a hole or boss. Because HI-1000 obtains high bulk toughness from rubber-particle cavitation, the weld-line zone retains a lower effective rubber concentration and often fails at 40–60 % of the virgin notched Izod value. To improve weld-line integrity, the mould should place gates so that flow fronts meet at a corner rather than in a flat load-bearing surface, and the melt temperature should be raised to 220–230 °C while keeping residence time below 5 min. Cavity pressure transducers at the weld-line region are preferred over manual shot-size adjustment for monitoring packing reproducibility; production-scale runs show that cavity-pressure variation above ±5 % can produce measurable weld-line strength scatter. These production-scale values are tooling-specific and should be verified by destructive sampling.

Chemical compatibility under ISO 175 is a restricted zone. ABS HI-1000 resists dilute acids, alkalis, and aliphatic hydrocarbons but is attacked by ketones, esters, chlorinated solvents, and aromatic hydrocarbons, which swell the SAN matrix and stress-crack the moulded part. For parts exposed to sunscreens, hand creams, or cleaning agents, compatibility testing is mandatory; polar contaminants can reduce notched Izod by 20–40 % after 24 h of strained contact. The processing staff should avoid release sprays containing chlorinated paraffins and silicone compounds when parts are intended for subsequent painting or electroplating, because surface contamination migrates to the adhesive interface and lowers adhesion. For glued assemblies, cyanoacrylate adhesives are generally suitable for non-loaded joints, but some slow-curing anaerobic adhesives can induce stress cracking in ABS; bond strength under tensile shear should be measured on moulded specimens, not on plaques.

Solvent-borne coatings for ABS are based on compatible acrylic or urethane systems; aggressive thinners containing toluene or methyl ethyl ketone can etch the SAN surface and produce microcracking, reducing impact strength before topcoat appearance is affected. Adhesion tests under ISO 2409 on moulded plaques should be performed after 24 h conditioning. High-gloss black parts are often painted with a two-pack polyurethane; the moulded substrate should be flame- or corona-pretreated to 38–44 dyn/cm surface energy measured by wetting fluids. Electroplated parts require a separate etch-grade control; lot-to-lot variation in polybutadiene grafting can shift adhesion by 10–20 %, and suppliers’ melt-flow data do not capture this variable.