Toray Industries ABS 844V-X05, sold under the Toyolac trade name, is a flame-retardant acrylonitrile–butadiene–styrene injection-moulding grade intended for thin-wall enclosures and structural parts in electrical and electronic equipment. The material is specified where a finished part at 1.5 mm wall thickness must achieve UL 94 V-0 without secondary flame-retardant coatings or barriers. Representative supplier data list a density of 1.19 g/cm³ under ISO 1183-1, a melt volume-flow rate of 21 cm³/10 min at 220 °C with 10 kg loading under ISO 1133-1:2022, and a notched Charpy impact strength of 13 kJ/m² under ISO 179-1/1eA at 23 °C. The grade differs from general-purpose Toyolac ABS because the flame-retardant additive package raises density and melt flow while lowering tensile elongation and notched impact strength.

Property	Test method	Typical value
Density	ISO 1183-1	1.19 g/cm³
Melt volume-flow rate	ISO 1133-1:2022	21 cm³/10 min at 220 °C, 10 kg
Tensile yield stress	ISO 527-2	43 MPa
Nominal tensile strain	ISO 527-2	10 %
Flexural strength	ISO 178	67 MPa
Flexural modulus	ISO 178	2450 MPa
Charpy notched impact strength	ISO 179-1/1eA	13 kJ/m² at 23 °C
Charpy unnotched impact strength	ISO 179-1/1eU	60 kJ/m² at 23 °C
Heat deflection temperature	ISO 75-2/Af	79 °C at 1.8 MPa
Flammability	UL 94	V-0 at 1.5 mm
Mould shrinkage, in-house method	—	0.4–0.6 %

The tabulated values are typical data from supplier documentation and are not specification limits. Pigmented variants may show different melt viscosity and flame performance; the UL 94 rating should be confirmed for each colour concentrate.

What Separates 844V-X05 from General-Purpose Toyolac ABS Grades?

The principal difference is the flame-retardant additive system required to achieve UL 94 V-0 at 1.5 mm. In general-purpose Toyolac injection grades, published density values are typically 1.04–1.07 g/cm³, and notched Charpy impact values are commonly 18–25 kJ/m². In 844V-X05, the density rises to 1.19 g/cm³ because of the flame-retardant constituents and possible filler synergists; the notched Charpy value falls to approximately 13 kJ/m². Tensile yield stress at 43 MPa and flexural modulus at 2450 MPa remain within the range expected for a filled flame-retardant ABS, but the strain at break is lower than that of unfilled high-impact ABS. The melt is formulated for high flow into multi-cavity tools, with a melt volume-flow rate of 21 cm³/10 min; many general-purpose ABS grades with higher toughness exhibit lower flow. The trade-off is lower low-temperature ductility and a more brittle failure mode under high-speed loading such as drop impact of thin bosses.

Property	Toyolac ABS 844V-X05	General-purpose Toyolac ABS representative range
Density (ISO 1183-1)	1.19 g/cm³	1.04–1.07 g/cm³
Melt volume-flow rate (ISO 1133-1:2022, 220 °C, 10 kg)	21 cm³/10 min	10–30 cm³/10 min depending on grade
Notched Charpy impact (ISO 179-1/1eA, 23 °C)	13 kJ/m²	18–25 kJ/m²
Heat deflection temperature (ISO 75-2/Af, 1.8 MPa)	79 °C	84–89 °C
Flammability at 1.5 mm (UL 94)	V-0	HB in unmodified grades

The flame-retardant additive system in 844V-X05 creates a char front that inhibits flame spread and dripping. The exact chemistry is not published in the standard technical data sheet; public data for the brominated or phosphorus-based synergist ratio are limited. Compared with halogen-free flame-retardant ABS grades, 844V-X05 may offer different flow and elongation behaviour; the exact additive chemistry must be confirmed against the safety data sheet. Compared with flame-retardant polycarbonate/ABS blends, 844V-X05 typically provides lower heat deflection temperature and lower notched impact strength. Many flame-retardant PC/ABS grades report heat deflection temperatures above 90 °C at 1.8 MPa and notched Charpy values above 20 kJ/m², measured under ISO 75-2/Af and ISO 179-1/1eA. Published data for direct comparison with 844V-X05 under identical moulding conditions are limited; selection should be based on the end-product thermal and impact specification.

Before compounding or moulding, the granulate is dried in a desiccant hopper dryer with a dew point below -40 °C and an inlet air temperature of 80 °C for 3–5 h. The target residual moisture is below 0.05 % by weight. At ambient relative humidity above 60 %, open-container exposure is limited to 30 min; moisture uptake produces surface splay, silver streaks, and intermittent loss of UL 94 V-0 performance at the gate. Melt temperature measured at the nozzle is maintained between 210 °C and 240 °C. A three-zone screw with an L/D ratio of 20:1 to 25:1 and a compression ratio of 2.0:1 to 2.5:1 provides sufficient shear to disperse the flame-retardant package without excessive heat generation. Back pressure is set at 0.5–1.0 MPa, and screw rotation speed is limited so that total melt residence time does not exceed 5 min. At melt temperatures above 240 °C or residence times above 5 min, the flame-retardant system can degrade, producing yellowing, black specks, and reduced flammability.

Injection speed is normally medium to fast; shear rates above 10,000 s⁻¹ in gates are avoided because local heating generates additive decomposition and visible streak defects. The mould temperature is maintained between 30 °C and 60 °C. Higher mould temperatures improve weld-line strength and surface gloss but increase cycle time and sink-mark depth over ribs. For hot-runner tools, externally heated manifolds with stainless-steel flow paths are preferred; dead spots can retain degraded flame-retardant additive and release it intermittently into the melt stream.

Production-scale failure modes recorded for flame-retardant ABS grades of this type include irregular plate-out on cavity surfaces, gate blush, and cavity-to-cavity UL 94 variation when runner balance is poor. In a multi-cavity tool, outer cavities may fill at lower pressure and develop different flame-retardant additive orientation than centre cavities. Short-shot mapping and cavity-by-cavity UL 94 sampling are used during process validation. Published data for this specific product configuration are limited, so the variability must be characterized on the customer tool.

When Wall Thickness Falls Below 1.5 mm

UL 94 ratings are thickness-dependent, so the V-0 classification at 1.5 mm does not automatically extend to thinner sections. Published data for 844V-X05 at 0.8 mm and 0.75 mm are limited; production parts below 1.5 mm require testing on the actual tool because gate type, flow length, and mould temperature change flame-retardant additive distribution. Thin sections increase shear heating and can produce local additive orientation that alters char formation. For gate sizing in thin-wall housings, a gate land length below 0.5 mm and a gate diameter above 1.0 mm are typical starting points, but specific values depend on flow length and wall thickness. Bosses should have a base radius of 0.5–0.7 times the nominal wall thickness, and weld lines should not be placed in snap-fits because the notched Charpy value of 13 kJ/m² is lower than in general-purpose ABS. If a weld line cannot be relocated, local mould temperature profiling or overflow wells are required to raise weld-line strength.

The Influence of Regrind Content on Flame-Retardant Performance

Closed-loop regrind from sprues and runners is often reused, but flammability ratings are not automatically retained. The thermal history of first melt processing modifies the flame-retardant package, and published data for 844V-X05 at specific regrind ratios are limited. Industrial practice for similar flame-retardant ABS grades commonly limits regrind content to 20 wt% for non-appearance parts; higher levels can reduce tensile elongation, lower notched impact, and shift the UL 94 result from V-0 toward V-1 or V-2. Because this grade is specified for fire enclosures, any use of regrind should be validated by moulding plaques and testing under the same wall thickness as the production part. Gravimetric dosing is preferred over hand-mixing to prevent local concentrations of degraded material. Barrel vacuum venting is recommended to remove volatiles from reprocessed material.

Part design for 844V-X05 follows the principles established for filled flame-retardant ABS. Sharp internal corners are radiused at 0.3–0.5 times the wall thickness to reduce stress concentration. Published data for the coefficient of linear thermal expansion of this specific grade are limited, but the material’s published heat deflection temperature of 79 °C at 1.8 MPa indicates that continuous load-bearing exposure above 70 °C can produce creep. Metallic inserts and mounting bosses should be supported by ribs rather than isolated bosses. For ultrasonic welding, the flame-retardant package can increase melt viscosity at the joint, so amplitude and weld time must be developed on production fixtures. In snap-fit assemblies, the lower notched impact value requires a more generous snap-fit root radius and reduced assembly speed to avoid brittle fracture.

Compliance documentation for 844V-X05 should be requested from the supplier for each production lot when the part is used in equipment certified under IEC 62368-1. The material is often listed in supplier certificates for UL 94 V-0 at 1.5 mm, but end-product certification remains the responsibility of the equipment manufacturer under IEC 62368-1 and UL 746C. Electrical property claims, if required, should be anchored to IEC 62631-3-1 for volume resistivity and IEC 60243-1 for dielectric strength. REACH and RoHS declarations must be verified against the current safety data sheet and product certificate; a generic statement that the grade is RoHS compliant without specifying exemption category is insufficient for audit. Published data for migration in food-contact or medical applications are limited, and no food-contact or medical approval should be assumed.

On production-scale injection machines, 844V-X05 is used in monitor rear housings, AC adaptor cases, printer paper cassettes, and battery-charger enclosures. Clamp force requirements depend on projected area and flow length; multi-cavity housings often use machines from 80 to 180 tonnes, but the exact value must be calculated from the tool layout. Because the melt flow is higher than in many general-purpose ABS grades, filling pressure can be lower, but packing pressure must still be controlled to avoid sink marks over ribs and bosses. Weld lines in high-flow flame-retardant ABS have reduced strength; gate relocation, overflow wells, or local temperature profiling are used to shift weld lines away from snap-fits and screw bosses. Hot-runner systems should use externally heated manifolds with stainless-steel flow paths and avoid dead spots where flame-retardant additive can accumulate. End-of-run purging with a general-purpose ABS or styrenic purging compound prevents cross-contamination when switching to non-flame-retardant grades.