Sinopec INEOS Styrolution ABS GP-22 is an unfilled general-purpose acrylonitrile-butadiene-styrene injection-moulding grade supplied as cylindrical pellets. The material is designated under ISO 1043-1 as ABS and is normally specified where a production requirement exists for a balance of melt flow, surface gloss, dimensional stability, and moderate impact resistance in technical parts with wall thicknesses between 1.5 mm and 3.5 mm. The grade is not impact-modified beyond the base polybutadiene rubber content; where low-temperature ductility or high-energy impact absorption is required, alternative high-impact ABS grades within the Sinopec INEOS Styrolution portfolio require evaluation. The data summarised here are compiled from the producer’s published technical information and from production-scale processing records. Because commercial ABS grades exhibit batch-to-batch variation and colourant-dependent changes, incoming inspection should include ISO 2580-2 designatory properties before mould qualification.

Within the general-purpose ABS class, the GP-22 model code denotes a medium-flow, high-gloss product. The flow position is intended to bridge the gap between slower high-impact grades and fast thin-wall grades; however, it is not positioned as a low-gloss or low-emission automotive interior grade. Processors requiring low volatile organic compound emissions should request data under VDA 277 and evaluate a dedicated low-emission ABS grade if the application specification demands low interior-fogging values.

Which Datasheet Values Characterise the Unfilled GP-22 Injection-Moulding Grade?

The representative values in the accompanying table are not specification limits. They were generated using the cited methods on injection-moulded specimens in the dry-as-moulded state; the processor should request the current certificate of analysis for each production lot.

The melt volume-flow rate of 19 cm³/10 min at 220 °C under 10 kg places GP-22 in the medium-flow segment. It supports filling of a 2 mm-wall part with a flow length of approximately 120 mm at moderate injection pressure; longer flow paths require multiple gates or a higher melt temperature within the recommended window. The tensile yield stress of 45 MPa and notched Charpy of 17 kJ/m² at 23 °C indicate a stiff, moderately ductile response, while the notched Charpy of 8 kJ/m² at -30 °C confirms that the grade is not intended for sub-zero impact service.

Because ABS GP-22 is hygroscopic in uncontrolled ambient conditions, moisture content above 0.1 wt% can develop when pellets are stored at relative humidity above 60%. Pre-drying in a desiccant hopper dryer at 80 °C for 2–4 h with a dew point below -20 °C is required before processing; dry-air ovens are acceptable only if the bed depth does not exceed 50 mm and air circulation is continuous. Dew points above -15 °C or residence times shorter than 1 h produce splay, silver streaks, and loss of surface gloss in moulded parts. The residual moisture content of dried granules should be checked with a Karl Fischer titrator or hot-moisture analyser before start-up when the ambient relative humidity exceeds 60%.

A melt temperature window of 230–260 °C at the nozzle and a mould-surface temperature of 40–80 °C are typical for uncoloured GP-22. On a hydraulic injection moulding machine with a 35 mm diameter general-purpose screw, L/D 20, and compression ratio 2.0–2.5, stable operation is usually obtained at a melt temperature of 240 °C, mould temperature 60 °C, injection velocity 70–90 mm/s, hold pressure 35–45 MPa, and back pressure 0.5–1.0 MPa. Short screw designs with L/D below 18 may require the upper melt-temperature limit to disperse the polybutadiene phase; above 260 °C, thermal degradation of the butadiene phase increases brown-spec formation and reduces notched Charpy by 5–10%. Melt residence time should be kept below 10 min at 240 °C; longer residence increases yellowing and melt-pressure instability. Where regrind use is permitted, the maximum addition level should be set at 20 wt% and validated by ISO 527-2 tensile tests and ISO 179-1/1eA impact tests because shear-history-induced chain scission lowers impact resistance.

The material’s melt-pressure response in the screw’s metering zone is sensitive to back pressure. At 240 °C and screw speed 60–90 min⁻¹, a back pressure of 0.5–1.0 MPa assists homogenisation of the rubber phase; raising back pressure above 1.5 MPa increases shear heating and may push the melt temperature beyond 260 °C in small shot-capacity machines. In multi-cavity tools with more than 8 cavities, melt-temperature differences of 3–5 °C across the hot-runner manifold can produce visible gloss differences; manifold balancing and independent heater control are required for parts with Class A surfaces. Injection velocity should be set so that the flow-front velocity remains below 300 mm/s at gate locations to prevent jetting and gate blush. For moulds with pin gates, a two-stage velocity profile is often necessary, with an initial velocity of 30–50 mm/s until the gate is filled and a subsequent velocity up to 90 mm/s for cavity filling.

Linear mould shrinkage for GP-22 typically ranges from 0.4% to 0.7% when measured after 48 h at 23 °C on a 2 mm plaque. Shrinkage in the flow direction is generally lower than transverse shrinkage by 0.05–0.15%; therefore, gate location and packing time influence warpage in flat panels. For a 2.0 mm-wall electronic housing moulded on a 120-tonne clamp-force machine, cavity-pressure sensors record gate-seal times of 3–5 s; hold-pressure duration shorter than gate seal causes sink marks, while hold pressure above 50 MPa can generate flash and mould damage. Weld lines in GP-22 retain approximately 60–70% of virgin tensile strength when melt fronts merge at high temperature; mould temperatures below 40 °C reduce weld-line strength and produce visible knit lines. Direct hot-runner systems require sequential valve-gate control when flow-length-to-wall-thickness ratios exceed 100:1 to prevent flow-front hesitation and gas entrapment.

When GP-22 is used as a carrier resin in masterbatch or is compounded on a co-rotating twin-screw extruder with L/D 40, barrel temperatures from 200 °C in the feed zone to 230 °C in the metering zone are preferred. Above 260 °C, the polybutadiene phase degrades and generates brown specks; off-gassing increases, and strand pelletising can become unstable due to reduced melt strength. For simple blending operations, a single-screw extruder with a barrier screw and vacuum venting at -0.08 MPa gauge is acceptable if the feed pellets have been pre-dried to below 0.05 wt% moisture.

When Grade Substitution Between GP-22 and Other ABS Types Is Under Review

Direct substitution into existing tools should not proceed without rheological and mechanical revalidation. Compared with high-flow ABS grades having MVR above 30 cm³/10 min at 220 °C/10 kg, GP-22 fills shorter flow paths and may require a 10–20 °C higher melt temperature or 5–15% higher injection pressure to maintain the same gate-to-fill time. In exchange, GP-22 generally provides higher notched Charpy at 23 °C and better surface gloss retention than many high-flow ABS products. Compared with high-impact ABS grades, GP-22 has lower polybutadiene content, which lowers melt elasticity and improves surface replication but reduces low-temperature notched Charpy below 10 kJ/m²; high-impact grades may report values from 20 kJ/m² to 35 kJ/m² at 23 °C, depending on butadiene content and rubber particle morphology. Substitution of GP-22 for glass-fibre-reinforced ABS is not permissible without redesign because the unfilled tensile modulus of 2300 MPa is 50–60% lower than typical short-glass ABS values of 5000–7000 MPa. The relevant designatory properties under ISO 2580-2 should be compared directly, and a full mould trial should be run because differences in the pressure-specific-volume relationship of the melt alter packing and shrinkage.

Published capillary rheometry data for neat GP-22 is limited; processors should obtain the producer’s Moldflow data file rather than using generic ABS viscosity coefficients. Generic ABS shear viscosity data cannot capture lot-specific rubber particle size distribution effects on pressure drop. Mould-filling simulation should be adjusted against short-shot data from production tooling because the non-isothermal shear-thinning behaviour of ABS GP-22 differs from that of unfilled polycarbonate/ABS blends near the gate freeze-off region. In particular, viscosity coefficients fitted for low-flow ABS grades will overpredict pressure drop in hot-runner drops and underestimate weld-line temperature depression.

GP-22 is supplied as natural pellets; custom colourants can shift melt flow and impact by 5–15% depending on carrier resin and pigment loading. Colour masterbatches with a polyethylene carrier can create delamination and surface streaking in ABS; a styrene-acrylonitrile carrier should be used and validated by ISO 527-2 tensile testing of moulded plaques. The presence of certain organic pigments can lower the Vicat temperature by 2–5 °C and alter UL 94 classification; the processor should request colour-specific UL yellow card data if coloured parts are required. External mould-release agents based on ethoxylated amines should be avoided when parts will be painted or ultrasonically welded; these agents can migrate to the surface and reduce paint adhesion. Zinc stearate at concentrations above 0.2 wt% can reduce gloss and increase environmental stress cracking sensitivity.

Applications for Sinopec INEOS Styrolution ABS GP-22 are generally confined to non-load-bearing interior components and enclosures unless the end-use performance is validated by a recognised standard. Typical production uses include appliance control-panel fascias, electrical-device housings, office-equipment front covers, and thin-wall automotive interior trim that does not require high heat resistance. The compliance matrix below summarises the standard documents that must be checked for a given application.

In electrical enclosures, the producer’s UL yellow card should be consulted for the actual UL 94 classification, commonly HB at 1.5 mm for uncoloured material; for toys, the finished article must meet EN 71-3 migration limits and applicable REACH Annex XVII restrictions. Food-contact use is not inherent; the processor must obtain the producer’s food-contact statement under 21 CFR 177.1020 and validate migration with the intended food simulant. The standard compliance position is covered by the producer’s REACH SVHC declaration, which typically states no SVHC above 0.1 wt%; RoHS Directive 2011/65/EU limits are met only for the unfilled, uncoloured resin, and the processor remains responsible for pigments and other additives.

Processing failures observed with GP-22 in multi-cavity tools are most frequently traced to incomplete drying, excessive melt residence time, or unbalanced hot-runner heating. Splay on the surface is usually moisture-related; brown specks are usually thermal degradation; gloss mottle is usually caused by mould-temperature variation or excessive regrind content. In a hot-runner mould with 12 cavities, temperature differences of 3–5 °C can shift the colour of unpigmented material from neutral white to cream; this is not a formulation defect but a thermal-oxidative response in the rubber phase.

The product is not recommended for continuous immersion in strong acids, ketones, esters, aromatic hydrocarbons, or chlorinated solvents; these media soften or dissolve the styrene-acrylonitrile phase and can induce environmental stress cracking. Hot water above 60 °C and high-pH detergent solutions may attack the nitrile segment during prolonged exposure. Published chemical-resistance data for this specific grade in multi-component fuel blends is limited; end-use testing with the actual chemical environment is required before production release.