Lotte Chemical Starex ABS NS-1610 is a multicomponent injection-moulding grade composed of a continuous styrene-acrylonitrile matrix with dispersed polybutadiene rubber domains. The product is positioned for parts where a controlled reduction in melt viscosity must be achieved without lowering the heat-deflection temperature below the threshold required for electrical enclosures, small appliance housings, and interior automotive bezels. The grade is supplied as cylindrical pellets; incoming moisture content before storage is normally below the moulding limit but may increase during open silo storage in humid ambient conditions. The polymer is not self-extinguishing in its natural form and is generally classified as UL 94 HB, not V-0, unless an additional flame-retardant package is specified.

Can NS-1610 Fill Thin-Wall Multi-Cavity Tools Without a PC/ABS Blend?

Flow behaviour is the primary selection criterion for NS-1610. Under ISO 1133-1:2022, the melt volume-flow rate of this grade family is commonly found in a window between 20 cm³/10 min and 35 cm³/10 min at 220°C under 10 kg. This is higher than high-impact ABS grades in the same portfolio, which may fall between 5 cm³/10 min and 15 cm³/10 min. The elevated flow permits fill of wall stocks below 1.0 mm in hot-runner tools with gate diameters of 0.8 mm or less, but published data for this specific configuration is limited. The trade-off is lower notched impact resistance because the rubber-phase volume is reduced relative to high-impact ABS.

Capillary rheometry performed according to ISO 11443:2021 indicates that the apparent viscosity ratio between NS-1610 and a high-impact ABS at a shear rate of 1000 s⁻¹ is typically between 0.6 and 0.8. In hot-runner systems, this requires lower manifold pressures but also narrows the processing window near the gate; melt temperature control should remain within ±5°C of the selected mid-point to avoid gate freeze-off or material burn. Hot-runner manifolds with internal thermocouple placement and external heating bands are preferred over simple valve-gate systems without zone control. Spiral-flow data from production-scale injection moulding machines with clamp force between 800 kN and 12,000 kN show fill improvement over high-impact ABS, though the exact spiral-flow length is tool- and gate-dependent and should be validated on the intended mould.

Pellet drying is mandatory after open storage or when ambient relative humidity exceeds 60%. Desiccant-bed dryers operating at 80°C for 2 h to 4 h until the residual moisture content is at or below 0.1% by mass are specified for ABS of this category; the moisture threshold is not a recommendation but an empirical defect boundary. Dew-point values in the drying circuit should remain at or below −20°C. If these conditions are not maintained, splay and silver streaks appear on texturised surfaces, and the notched impact value can decline because of volatile expansion at the flow front. Feed throat settings below 60°C prevent pellet bridging, while hopper magnets remove ferrous contamination before plastication.

Mechanical Property Windows Across a 200–250°C Melt Curve

Component designers should use the following comparative windows as engineering estimates. The values represent unfilled natural ABS class data and are not lot-specific certificates. Lot-specific values must be obtained from Lotte Chemical or the compounder before release testing. The addition of colour masterbatch, antistatic packages, or processing aids can shift individual values by up to ±10%.

The mechanical data indicate that NS-1610 trades impact energy for stiffness and flow. This distinction matters in thin-walled structural ribs, snap-fit features, and bracketry where excessive rubber content leads to sink marks, warpage, or incomplete packing. When a design requires an unnotched impact value above 30 kJ/m² or a notched Izod above 20 kJ/m², a high-impact ABS or PC/ABS blend should be selected instead. For electrical components tested under IEC 60243-1, the short-term dielectric strength of unfilled ABS is typically between 25 kV/mm and 40 kV/mm, but final values depend on wall thickness, filler content, and conditioning.

When Regrind Ratio Exceeds 20% in Multi-Cavity Tools

Regrind use is a significant source of lot drift in NS-1610. The molecular weight distribution of ABS narrows with repeated heat history, and the polybutadiene phase can undergo crosslinking under high temperature or high shear. In moulding trials with twin-shear screw plastication, addition of 20% clean runner regrind has been observed to reduce spiral-flow length by 5% to 12% and increase yellowness index measured under ISO 7724-2. When regrind ratios exceed 30%, the notched Izod value may fall to the lower edge of the design window. The feed blend should be metered gravimetrically, and the regrind stream should be screened through a 2 mm mesh to remove flake fines and metal debris. Re-stabilisation or addition of virgin resin at 70% by mass or higher is required for critical external parts.

Process parameter boundaries for NS-1610 injection moulding are summarised in Table 2. These are empirical ranges for unfilled natural ABS and must be adjusted for coloured or customised grades.

When processing at the upper melt-temperature limit, the thermal stabiliser package must be confirmed for the specific lot. Residence time should not exceed 10 min in the barrel because prolonged exposure above 260°C initiates butadiene-phase degradation, producing free rubber radicals that can reduce surface gloss and increase odour. Screw recovery settings should avoid excessive shear heating; a compression ratio below 2.3 may be used for high-flow grades to minimise melt-temperature overshoot. Tool temperature influences gloss, shrinkage, and weld-line strength. On polished mould surfaces, a tool temperature of 60°C improves gloss uniformity, while lower temperatures between 40°C and 50°C may increase moulded-in stress but shorten cycle time.

Secondary finishing of NS-1610 parts requires careful solvent selection. Ketone-based solvent bonding can be used under controlled ventilation, but concentrated methyl ethyl ketone exposure produces environmental stress cracking at gate bosses and weld lines. Ultrasonic welding of unfilled ABS typically uses energy director angles between 60° and 90° and amplitudes in the range 20 µm to 40 µm; higher amplitudes may cause localised overheating and fracture of thin-wall sections. Mechanical fastening should avoid excessive insertion torque; a boss with an outer diameter of 4 mm should not be loaded beyond 0.5 Nm unless the boss design includes gussets and a stress-relief radius. The material is not recommended for continuous service above 90°C or for direct outdoor exposure unless a UV-stabilised grade is specified. Chemical contact with aromatic solvents, concentrated acetic acid, or brake fluid should be avoided at ambient temperature and is unacceptable above 40°C.