Identity, Designation, and Standard Classification

Versalis SINKRAL B 422 is an acrylonitrile-butadiene-styrene injection moulding grade supplied in pellet form and classified under ISO 2580-1:2003 as an ABS material. The producer positions the grade for general-purpose technical components requiring a balance of melt fluidity, notched impact resistance, and dimensional stability. Melt volume-flow rate is measured in accordance with ISO 1133-1:2022 at 220 °C under 10 kg; representative published values fall between 20 cm³/10 min and 26 cm³/10 min. Density by ISO 1183-1:2019 is 1.04 g/cm³ to 1.05 g/cm³. Vicat softening temperature tested to ISO 306/B50 is typically 94 °C to 98 °C. Lot-specific values should be taken from the producer’s technical data sheet and certificate of analysis; differences in specimen preparation to ISO 294-1 shift notched impact and heat deflection values by several units.

Before melt processing, residual moisture must be reduced below 0.05 %; at ambient relative humidity above 60 % or after storage in unsealed containers, pre-drying in a desiccant hopper dryer with a dew point not higher than -25 °C is mandatory. A typical drying condition of 80 °C for 4 h to 6 h is applied on production lines. Inadequate drying of ABS produces surface splay, weakens weld lines, and increases batch-to-batch scatter in ISO 180/1A notched impact. In hot-air hopper dryers, extended residence above 90 °C should be avoided because the butadiene-rubber phase can yellow. The feed throat should be protected by magnetic grates and fines separators; hopper residence at temperature should not exceed 24 h.

What Processing Parameters Require Tight Control for This Grade?

The injection moulding window for SINKRAL B 422 is governed by melt temperature, cavity-wall temperature, injection velocity, and hold-pressure decay. Barrel set points from rear to nozzle are normally ramped from 190 °C to 230 °C, with air-shot melt temperature not exceeding 260 °C. Mould tempering circuits should hold cavity-wall temperature between 40 °C and 80 °C; the upper half of the range is used for high-gloss surfaces and the lower half for fast cycle times. Back pressure is set at 3 bar to 7 bar hydraulic, and screw recovery speed is limited below 15 m/min to limit rubber-phase shear heating. Nozzle contact force is maintained at 3 kN to 5 kN. Peak hold pressure is normally 60 % to 80 % of peak injection pressure, with hold time equal to the gate-seal time determined by the part-weight plateau.

On a 1200 kN hydraulic clamp injection moulding machine with a general-purpose screw of 20:1 L/D and compression ratio 2.5:1, fill studies show melt-pressure drop through a cold runner of 6 mm diameter and 80 mm length remains below 8 MPa at a volumetric flow rate of 60 cm³/s. For cavity wall thickness below 1.5 mm, injection velocity should be increased to 120 mm/s to 200 mm/s to prevent premature freeze-off. For sections above 4 mm, lower screw speed and higher mould temperature reduce sink marks and internal voids; published data for this specific configuration is limited.

Representative mechanical data generated on injection-moulded specimens according to the cited ISO methods are summarised below. Values are indicative, not lot-release minima.

Charpy notched impact determined by ISO 179-1/1eA at 23 °C is typically 25 kJ/m² to 30 kJ/m². Low-temperature Charpy impact at -30 °C falls below 10 kJ/m², which defines a boundary for freezer applications.

Comparing SINKRAL B 422 with Medium-Flow and High-Heat ABS Grades

The primary differentiation from lower-flow ABS grades is the melt viscosity–impact trade-off. SINKRAL B 422 has a higher melt volume-flow rate than general-purpose ABS grades in the range of 5 cm³/10 min to 12 cm³/10 min, which permits shorter fill times in multi-cavity and thin-wall tools. This fluidity increase is achieved without the impact reduction to below 20 kJ/m² at 23 °C that is commonly observed in high-flow ABS grades with MVR above 35 cm³/10 min. In comparison with high-heat ABS grades having Vicat softening temperature above 105 °C, SINKRAL B 422 has a lower heat distortion temperature and a lower intrinsic viscosity; it is therefore less suitable for components exposed continuously to air temperatures above 85 °C but more suitable for rapid filling of complex housings. When compared to halogenated flame-retardant ABS grades, SINKRAL B 422 is typically supplied as UL 94 HB and does not carry a V-class rating at 1.5 mm or 3.0 mm.

In thin-wall electrical enclosures and appliance housings with nominal wall thickness between 2.0 mm and 3.5 mm, SINKRAL B 422 can be processed in multi-cavity tools with hot-runner valve gating. In a 12-cavity connector housing mould run on a 900 kN toggle clamp machine, successful filling is achieved with gate diameter not less than 0.8 mm and flow length-to-thickness ratio below 150:1. The material delivers dielectric strength above 20 kV/mm when tested according to IEC 60243-1 on conditioned specimens at 23 °C and 50 % RH. This electrical performance, however, is moisture-sensitive; absorbed water reduces breakdown voltage and increases dielectric dissipation factor, so parts should be assembled dry or stored in sealed packaging.

When Regrind Ratios Exceed 20 % in Thin-Wall Moulding

Regrind addition is possible up to 20 % by weight without pronounced loss of notched impact, provided the regrind is dried to the virgin-material specification and is free of dust and foreign polymer. Beyond 20 %, lot-to-lot variability increases because the butadiene phase undergoes progressive thermo-oxidative crosslinking during repeated residence and shear. On production-scale lines, this appears as screw recovery-time drift, cushion instability, and a shift in melt volume-flow rate of more than 3 cm³/10 min. In thin-wall components below 1.8 mm, regrind addition above 30 % has been associated with gate blush, burn streaks at the end of fill, and part-mass scatter greater than 0.1 g across a 4-cavity tool. Cumulative melt residence time should be limited to 20 min; after shutdown, the barrel should be purged with a viscosity-matched ABS.

Compliance statements must be verified against the producer’s certificate because SINKRAL B 422 is supplied as a general-purpose grade and is not automatically food-contact or medical-grade. Regulatory conformity for RoHS recast 2011/65/EU and REACH Regulation (EC) No 1907/2006 is normally addressed through raw-material declarations for each lot. The material is not recommended for service in contact with ketones, esters, aromatic hydrocarbons, or chlorinated solvents, because these agents migrate into the butadiene-rubber phase and initiate environmental stress cracking. For low-temperature impact applications below -30 °C, a polycarbonate/ABS blend or a high-rubber ABS should be chosen, because SINKRAL B 422 notched Izod impact according to ISO 180/1A falls below 10 kJ/m² at -30 °C.