Sinopec INEOS Styrolution ABS 967K is a high-flow acrylonitrile-butadiene-styrene terpolymer supplied as natural and pre-coloured pellets and positioned for injection moulding of thin-wall appliance housings, consumer electronics enclosures, and interior trim components. The grade designation 967K places the material in the medium-impact, high-flow segment of the manufacturer’s ABS portfolio; the K suffix can denote a regional additive or release-agent package and should be confirmed against the current regional technical data sheet. Melt volume-flow rate is measured according to ISO 1133-1:2022 at 220 °C under a 10 kg load. For this grade, the value typically falls between 20 cm³/10 min and 30 cm³/10 min, depending on colour concentrate and lot. Regulatory declarations for RoHS Directive 2011/65/EU and REACH Regulation (EC) No 1907/2006 are usually available from the supplier for the base resin, but these declarations do not imply food-contact or medical-grade status.

Which Processing Parameters Follow from the Melt Flow Behaviour?

The high-flow rheology of 967K reduces the hydraulic pressure required to fill long flow paths compared with medium-flow ABS. On reciprocating-screw injection moulding machines with screw diameters from 40 mm to 70 mm and L/D ratios of 20:1 to 24:1, the nozzle melt temperature is maintained between 220 °C and 250 °C. For wall sections below 2.0 mm, the nozzle set point is shifted toward the upper third of this range, while the mould surface temperature is held at 40–70 °C. Rear-to-front barrel zones are typically 210–220 °C, 225–235 °C, 230–240 °C, and 235–245 °C. Back pressure is limited to 5–10 bar hydraulic pressure to avoid excessive shear heating, and screw rotation is set to a peripheral velocity of 0.15–0.30 m/s.

Specific injection pressure is normally set at 60–100 MPa, with holding pressure maintained at 50–70 % of the peak injection pressure. Shot size should remain between 40 % and 70 % of barrel capacity, and the melt cushion is held at 3–6 mm. The residence time above 240 °C should not exceed 5 minutes; if a stoppage is expected, barrel temperatures are reduced to 150 °C or lower. Purging after extended runs is performed with SAN or GPPS at 230 °C, because the polybutadiene phase generates carbonaceous deposits on screw and check-ring surfaces if overheated.

Thermal and Mechanical Property Boundaries Under ISO 527-2 and ISO 179-1

Mechanical values are generated on multipurpose test specimens moulded according to ISO 294-1:2017. The tensile yield stress measured under ISO 527-2:2012 at 50 mm/min on Type 1A specimens with 4 mm thickness is typically 42–48 MPa. Flexural modulus according to ISO 178:2019 is in the range 2000–2400 MPa. Charpy notched impact strength under ISO 179-1/1eA:2010 at 23 °C is usually 15–22 kJ/m², declining to 7–11 kJ/m² at -30 °C. The Vicat softening temperature, method B50 under ISO 306:2022, is generally 94–98 °C, while heat deflection temperature under ISO 75-2:2013 at 1.8 MPa is 88–94 °C. These values define a medium-impact, high-flow ABS rather than a high-impact extrusion or thermoforming grade.

When 967K is used in housings with nominal wall thickness between 1.8 mm and 2.5 mm, the higher melt-flow capability shifts the principal processing risk from short shots toward jetting, weld-line visibility, and gas entrapment. Vent depth at the parting line should be 0.02–0.03 mm for unplated parts, and the flow-front velocity should remain below 300 mm/s to limit silver streaking and surface delamination around the gate. For a projected part area of 100 cm², the maximum cavity pressure of 30–50 MPa yields an estimated clamping-force requirement of 300–500 kN. Hot-runner systems with multiple drops should be balanced to within 5 % of the nominal fill time; if imbalance exceeds 10 %, the higher shear in the restricted channel can locally degrade the polybutadiene phase and produce yellow streaks. Production trials on two-platen clamp systems of 800–2500 kN indicate that shot-to-shot mass variation increases when hot-runner residence time exceeds 8 minutes, particularly with manifold temperatures more than 10 °C above the nozzle set point. Valve-gated hot runners with pneumatic actuation are preferred over thermal gate shutoff when colour changes are frequent, because the butadiene-rich phase tends to form deposits on heated gate surfaces more readily than the SAN continuous phase.

Weld-line strength in 967K is governed by the coalescence of polybutadiene domains at the flow front. The rapid solidification of the high-flow SAN phase lowers interfacial entanglement at knit lines, so the notched impact strength at a weld line can be 40–60 % of the un-welded value. To reduce this loss, the melt temperature and injection velocity should be raised within the allowable range, and the mould temperature should be increased to the upper end of the 40–70 °C window. Published instrumented falling-weight data for this specific grade is limited; component-level weld-line validation under ISO 6603-2:2023 is recommended for load-bearing enclosures.

When Part Ejection Tolerances Require Shrinkage Compensation Below 0.7 %

Mould shrinkage measured according to ISO 294-4:2018 is generally 0.4–0.7 % parallel to flow and 0.5–0.8 % transverse to flow, depending on wall thickness, gate location, and mould temperature. The long flow length of 967K reduces packing-pressure loss in thin sections, but it also increases sensitivity to gate freeze time. For components with dimensional tolerances tighter than 0.1 mm, cavity-pressure decay should be used to confirm gate seal rather than a fixed timer, because premature gate freeze can increase transverse shrinkage by 0.1–0.2 percentage points. Holding pressure time should be extended until the cavity pressure at the gate has fallen to 95 % of its peak, which often corresponds to holding times of 4–8 s for wall sections of 2.0 mm.

Comparative Positioning Against High-Impact and Flame-Retardant ABS Grades

Compared with high-impact ABS grades having Charpy notched impact strengths above 25 kJ/m², 967K trades low-temperature impact tolerance for a melt volume-flow rate that is typically 40–60 % higher. The difference is achieved by controlling the polybutadiene particle-size distribution and the molecular weight of the SAN continuous phase, not by adding plasticiser. This shifts the material toward thin-wall injection moulding applications and away from thick-wall components where impact resistance is the limiting design criterion. In comparison with flame-retardant ABS grades, 967K is not inherently classified as UL 94 V-0; the base resin is generally classified UL 94 HB at thicknesses of 1.5 mm or greater. Where a specific flame rating is required, the relevant UL yellow-card listing and the compound revision should be obtained from the supplier, because published data for this specific configuration is limited and varies by colour.

Pre-drying is mandatory for 967K after a previously opened bag has been exposed to ambient relative humidity above 60 %. A desiccant dryer with a dew point of -30 °C or lower and an airflow of 1.8–2.5 m³/h per kg/h of resin throughput is operated at 80 °C for 2–4 hours. The target residual moisture is below 0.05 %; for high-gloss light colours, the target is tightened to 0.02 %. Over-drying beyond 6 hours at 80 °C may shift the colour coordinate and increase yellowing in natural grades. Regrind from sprues and runners is limited to 15–20 % by weight when dried and blended homogeneously with virgin pellets. Bulk storage should be in sealed containers below 30 °C, protected from UV radiation, because the polybutadiene phase undergoes photo-oxidative embrittlement that reduces notched impact strength before visible yellowing occurs.

Solvent Resistance, Additive Interactions, and Equipment Cleaning

967K is swollen or stress-cracked by ketones, esters, aromatic hydrocarbons, and certain chlorinated solvents. Cleaning agents containing acetone, methyl ethyl ketone, or toluene are unsuitable for wiping moulded parts or tool surfaces that contact the melt. Strong oxidizing acids and high loadings of some organophosphorus ester flame retardants are incompatible with the polybutadiene phase and can accelerate embrittlement. When changing from 967K to a higher-viscosity resin, the barrel is purged with SAN or GPPS at 230 °C until the melt is visually homogeneous. If the machine is stopped for more than 15 minutes, all barrel zones should be reduced to 150 °C or lower to prevent carbonization in the check ring and screw channels. The material should not be blended with ABS grades containing different lubricant packages or with styrene-acrylonitrile copolymers that have unknown release-agent chemistry unless compatibility is first confirmed by torque rheometry or melt-flow stability testing.

Colour concentrates and masterbatches can shift the continuous-phase viscosity and the polybutadiene particle stabilization. Low-molecular-weight colour carriers may increase melt volume-flow rate by 5–15 % but reduce Vicat softening temperature by 1–3 °C. Carbon-black formulations can increase flexural modulus slightly while decreasing notched impact strength; white TiO₂ loadings above 4 wt% may increase surface roughness and reduce gloss. The extrusion compounder should use twin-screw venting at -0.08 MPa gauge to remove volatiles without overheating the melt above 250 °C.