INEOS Styrolution ABS TERLURAN HI-22 is an acrylonitrile-butadiene-styrene injection-moulding grade in which a styrene-acrylonitrile matrix carries a dispersed polybutadiene rubber phase. The grade is positioned for technical parts requiring high impact toughness at temperatures down to -30 °C combined with melt-flow characteristics that allow multi-cavity and thin-wall filling. Published manufacturer data list a melt volume-flow rate of 19 cm³/10 min at 220 °C under a 10 kg load when tested to ISO 1133-1:2022. This places the material between slower high-impact ABS grades and general-purpose grades with higher flow but lower toughness. The designation HI-22 follows the Terluran nomenclature in which HI denotes high-impact modification and the suffix identifies the melt-viscosity range.

The product has a density of 1.04 g/cm³ measured under ISO 1183-1:2019 and a tensile yield stress of approximately 44 MPa when tested at 50 mm/min in accordance with ISO 527-2:2012. These values are typical, not minimum specification limits, and are generated from injection-moulded specimens conditioned at 23 °C and 50 % relative humidity according to ISO 291.

The tensile yield stress and flexural modulus define the short-term load-bearing capability of the material. The notched Charpy values show the expected toughness fall from 28 kJ/m² at 23 °C to 12 kJ/m² at -30 °C; this reduction is significant when components are assembled with snap fits, welded joints, or exposed to low-temperature impact in service. The difference between the Vicat softening temperature of 96 °C and the HDT/A value of 95 °C indicates that short-term thermal resistance is moderately balanced, but the grade is not intended for continuous load-bearing service above approximately 80 °C without design verification.

What Distinguishes TERLURAN HI-22 from GP-22 and HI-10 Within the Terluran Portfolio?

Grade selection in the Terluran line is generally controlled by two parameters: melt volume-flow rate and Charpy notched impact strength. HI-22 provides an intermediate MVR of 19 cm³/10 min with a 23 °C notched impact of 28 kJ/m². GP-22 is typically specified for shorter cycle times and thin-wall parts because its flow characteristics are higher, but its room-temperature notched impact is below the HI-22 level. HI-10 extends toughness further, particularly at low temperature, at the cost of lower MVR and therefore higher filling pressure or thicker walls. A converter selecting HI-22 avoids the impact penalty of a general-purpose grade without moving to the restrictive flow behaviour of an ultra-high-impact grade.

This distinction is most visible in multi-cavity tooling. Where a GP-22 grade may fill thin features more readily, it can fail low-temperature drop tests or assembly snap-fit requirements. Where an HI-10 grade may provide more impact resistance, it can require larger gates and longer holding-pressure times. HI-22 is therefore used when a moulder must fill complex geometry with wall thicknesses between 1.5 mm and 3.0 mm while retaining a notched impact value near 28 kJ/m² at 23 °C. Published datasheet comparison between Terluran grades should be reviewed for actual lot-specific values, because the MVR and impact values are controlled within production tolerances, not as fixed absolute limits.

For applications requiring chemical resistance to solvents or high-gloss aesthetic surfaces, HI-22 behaves as a conventional ABS: it has limited resistance to ketones, esters, and aromatic hydrocarbons, and its gloss depends on mould surface finish and processing conditions. These limitations are common to the Terluran ABS family and do not by themselves differentiate HI-22 from GP-22 or HI-10.

Prior to melt processing, the resin must be dried to a residual moisture content below 0.1 %. A desiccant dryer with a dew point of -30 °C or lower should be set to 80 °C for 2–4 h; the longer interval is required if regrind content exceeds 20 % or if the ambient relative humidity exceeds 60 %. Insufficient drying produces silver streaks and lowers weld-line strength because hydrolytic degradation of the styrene-acrylonitrile matrix reduces molecular weight. Splay from moist material appears as fan-shaped silver streaks radiating from the gate and is often mistaken for gas entrapment or mold release residue.

Melt processing on a general-purpose injection-moulding machine with an L/D ratio of 20:1 to 24:1 is normally carried out with a barrel-temperature profile of 200–220 °C in the rear zone, 230–250 °C in the middle zones, and 240–260 °C at the nozzle. The mould temperature should be held between 40 °C and 80 °C; lower mould temperatures increase frozen-in orientation and reduce surface gloss, while higher mould temperatures lengthen cooling time and may increase cycle time. Injection speed is set to fill the cavity in 0.5–1.5 s for wall sections of 1.5–3.0 mm, and the holding pressure is typically 50–80 MPa until gate freeze. A shot-weight cushion of 3–6 mm is recommended to prevent screw bottoming and reduce part-weight variation.

For clamp-force estimation, a moulded part with a projected area of 200 cm² and a cavity pressure of 40 MPa requires approximately 800 kN of clamp force. Thin-wall parts with wall thickness below 1.5 mm may require cavity pressures up to 60 MPa, increasing the clamp-force demand accordingly. Vent depths in multi-cavity tools should be kept at 0.02–0.03 mm to prevent burning at the flow front while avoiding flash. Gate diameters below 0.8 mm at high injection speeds can produce excessive shear heating and rubber-phase degradation, particularly in hot-runner systems with sharp bends or dead zones.

Thermal Degradation Accelerates Above 270°C in High-Shear Hot-Runner Channels

Although the melt-temperature window is specified to 260 °C, local melt temperatures in hot-runner manifolds and small gates can exceed the set value by 10–20 °C during fast injection. Prolonged residence time above 270 °C initiates rubber-phase crosslinking and SAN matrix discolouration; production experience shows visible brown streaking and a measurable drop in Charpy notched impact before dimensional symptoms appear. The processing window should therefore be treated as a boundary condition, not a target. Hot-runner channels with sharp bends, dead zones, or excessively narrow gates below 0.8 mm increase shear heating and generate black specks from degraded material. When scrap rates rise in multi-cavity tools, barrel and hot-runner thermocouple maps should be audited before adjusting impact-critical dimensions.

In high-shear plastication, the rubber phase can agglomerate if melt temperature and screw speed are too high. Screw peripheral speeds above 0.4 m/s with high back pressure can produce local friction peaks that are not visible on the barrel display. The recommendation for TERLURAN HI-22 is to maintain a melt cushion and avoid excessive back pressure; a back pressure of 0.3–0.7 MPa is usually sufficient for homogeneous melt quality without adding measurable thermal history. If black specks persist after reducing temperature and screw speed, the screw and non-return valve should be inspected for material hang-up.

Batch-to-batch variance in MVR is controlled by the manufacturer within specification limits, but converters should review the certificate of analysis before setting process parameters. A change in MVR of 2 cm³/10 min may not be visible in the part appearance but can alter filling pressure and gate freeze time in thin-wall tools. Process capability studies on production-scale equipment should be used to establish local control limits for cushion, peak injection pressure, and part weight.

When Mould Wall Temperature Falls Below 40°C, Weld-Line Strength and Surface Replication Are Compromised

At mould temperatures below 40 °C, the solidifying melt front recombines at a lower interfacial temperature, producing a weak weld line. Published ABS processing literature indicates that weld-line tensile-strength losses of 5–20 % can occur when mould temperature is reduced from 60 °C to 30 °C; the exact loss in TERLURAN HI-22 should be established by tool trials. Low mould temperature also prevents accurate replication of grain or polished-texture surfaces. Gloss measurements at 60° geometry may fall below 6 GU on textured surfaces intended for automotive interior matte finishes, even when the tool surface is correctly etched.

The recommended 40–80 °C mould-temperature range is therefore not merely a processing convenience; it is required to maintain mechanical integrity at flow-front confluence points and to meet appearance specifications. In multi-cavity tools with uneven cooling, differences of only 5 °C across the cavity surface can shift part dimensions and gloss. Moulds with conformal cooling channels are preferred where wall thickness varies from 1.5 mm to 3.0 mm and where cycle-time pressure demands high heat extraction. For applications with tight gloss tolerances, published data for this specific configuration is limited; cavity-specific gloss mapping is recommended before release.

Compliance Documentation and Regulatory Audit Matrix

Because HI-22 is not a flame-retardant grade, it is normally classified as UL 94 HB at 1.6 mm. Applications requiring V-2, V-1, or V-0 ratings must use a different Terluran grade or a compounded FR ABS. Food-contact uses require separate review; the grade is not automatically compliant with FDA 21 CFR food-contact polymer conditions. Suppliers should be asked for current regulatory statements, because compliance depends on the production site, formulation version, and regional additive controls.

In automotive interior trim, the combination of flow and impact is used for components such as air-vent assemblies, glove-box lids, and centre console side panels. A wall-thickness reduction from 3.0 mm to 2.0 mm benefits from the higher flow compared with a high-toughness low-flow grade, but the moulder must verify that the -30 °C Charpy value of 12 kJ/m² remains above the OEM low-temperature impact requirement. Automotive OEM approvals for ABS interior materials often require a Vicat B50 value of at least 90 °C and a defined elongation at break; HI-22 can typically satisfy these short-term heat and deformation requirements when the part is not subjected to continuous load above 80 °C.

Household appliance housings and small electrical enclosures are typical applications. For an enclosure with snap-fit assembly, HI-22 provides sufficient elongation at break and resistance to repeated assembly. The material is not designed for direct outdoor exposure; UV stabilization must be compounded separately if the article is used in direct sunlight. In white and light-coloured parts, thermal history above 270 °C produces yellowing that cannot be corrected by adding titanium dioxide. Moulders should evaluate melt cushion, hot-runner temperature, and residence time before adjusting colour formulation.

Toys and sports articles fall under EN 71-3 when marketed in the EU. The ABS base resin can be considered only if the final coloured or overmoulded article passes migration limits; colour masterbatches, paints, metallic pigments, and adhesives are frequent sources of heavy metals and must be assessed separately. Published data for this specific configuration is limited; batch-specific certificates are required for the finished article, not only for the raw resin.