Toray Industries ABS 300-325 is a medium-impact acrylonitrile-butadiene-styrene injection-moulding grade within the Toyolac 300 series. The product is formulated as a controlled-flow resin for thin-wall components and multi-cavity tools in which melt-front advance, packing-pressure transfer, and knit-line strength control the reject rate. Supplier-reported density is 1.03–1.05 g/cm³ under ISO 1183-1:2019, and melt volume-flow rate is 20–26 cm³/10 min at 220°C/10 kg under ISO 1133-1:2011. The 300-325 designation is applied to a pelletized compound that is not flame-retardant and is supplied without internal mould-release additives. It is differentiated from Toyolac 100 series materials by higher butadiene content and from Toyolac 500 series materials by lower impact resistance combined with lower melt viscosity. The grade is intended for injection moulding, not extrusion blow moulding or profile extrusion.

What Distinguishes the 300-325 Grade Within the Toyolac 300 Series?

The 300-325 variant is most clearly differentiated by its flow-to-impact balance. Under ISO 527-2:2012, tensile yield stress is reported at 40–46 MPa and elongation at yield at 2.5–3.5%. Flexural modulus under ISO 178:2019 is 2200–2500 MPa, with flexural strength of 60–70 MPa. Notched Charpy impact at 23°C is 18–24 kJ/m², falling to 8–12 kJ/m² at -30°C under ISO 179-1:2010. Heat deflection temperature is 76–82°C at 1.82 MPa and 84–90°C at 0.45 MPa when tested to ISO 75-2:2013. Rockwell hardness is 100–110 on the R scale under ISO 2039-2:1987. The combination of melt volume-flow rate above 20 cm³/10 min with notched Charpy impact above 18 kJ/m² is the principal reason the grade is selected over standard 300-series materials for parts requiring both rapid cavity filling and moderate toughness.

The comparative ranges are representative manufacturer datasheet values for uncolored natural grades. The 100 series is a high-flow general-purpose material with lower toughness, suitable for thin-wall parts with short flow lengths and low impact requirements. The 500 series is a high-impact material whose higher butadiene content increases melt viscosity and reduces flow length under identical injection pressure. The 300-325 grade sits between these positions; it is not a substitute for 500-series materials in cold-temperature impact applications or for 100-series materials when maximum filling speed is required. Batch-to-batch variation in rubber-phase crosslink density can shift notched impact and melt flow in opposite directions, so incoming lot acceptance should include both measurements rather than relying on one indicator.

Before melt processing, residual moisture must be reduced below 0.05 wt%. A desiccant-wheel dryer with a dew point below -40°C is used at 80°C for 3–4 h when ambient relative humidity is below 60%. At higher relative humidity or when pellet bed depth exceeds 50 mm, drying time is extended to 4–6 h or drying temperature is raised to 90°C. Moisture above the specified limit produces splay and silver streaking at the gate. In a 16-cavity hot-runner tool with valve-gate sequencing, moisture-induced splay is typically observed first in cavities nearest the sprue because the melt front in those cavities is fed by the hottest, least viscous stream. Drying hopper outlet temperature should be verified with a pyrometer; measuring inlet temperature alone masks heat loss across the conveying line and can leave wet pellets at the machine throat.

When Thin-Wall Moulding Replaces Standard ABS: Processing Window and Flow Behaviour

On a 120-ton hydraulic injection-moulding machine with a 25 mm screw and 20:1 L/D, the 300-325 grade is processed with a barrel temperature profile of 190°C rear, 200°C middle, 210°C front, and 220°C nozzle. Melt temperature measured in the air shot should remain between 200°C and 250°C. Nozzle melt temperatures above 260°C for residence times exceeding 15 min accelerate polybutadiene degradation, resulting in yellowing and a loss of notched impact of 10–20%. Mould temperature is maintained at 40–70°C with turbulent water channels. For wall thickness below 2.0 mm, the higher mould temperature condition is preferred because it keeps the flow front above the solidification temperature and improves knit-line strength. Injection velocity is set to produce a flow-front speed of 50–150 mm/s. Fill time is typically 0.5–1.5 s for thin-wall parts; transfer from velocity to pressure control occurs at 90–95% of fill volume.

Hold pressure is 40–70 MPa hydraulic, with hold time of 1–2 s/mm of nominal wall thickness. Back pressure is set at 0.5–1.5 MPa; screw speed is 50–100 rpm, and shot size is maintained between 30% and 70% of barrel capacity. A cushion of 3–6 mm prevents screw bottoming and stabilizes hold-pressure transfer. When these parameters are held, cavity-to-cavity mass variation in a balanced 16-cavity valve-gated tool can be maintained below 0.5%; variations above 1.0% usually indicate blocked hot-runner nozzles, worn check rings, or incorrect valve-gate opening timing. Shear heating in hot-runner manifolds should be limited by maintaining manifold and drop temperatures between 220°C and 250°C; higher temperatures increase the risk of gate blush and streaking in dark-colored parts.

Applications include appliance front panels, air-conditioner outlet louvers, electronic enclosures, and automotive interior trim where medium impact and high flow are both required. In these parts, UL 94 HB flame class at 1.5 mm or 3.0 mm thickness is usually cited for the uncolored grade; colored grades require re-evaluation because pigments alter ignition behaviour. The material accepts hot-stamping, in-mould decoration, and painting after surface treatment; adhesion to solvent-borne coatings is generally adequate after flame or plasma treatment. For electroplating, a specific plating-grade ABS is preferred, but 300-325 can be plated after acid etching if the supplier confirms that the polybutadiene surface distribution is suitable. Published data for this specific configuration is limited; plating adhesion should be validated on production-scale parts before release.

Competitive Separation From High-Impact and Heat-Resistant ABS Grades

The distinction between 300-325 and high-impact Toyolac 500 grades is primarily elastomeric content. Lower butadiene content reduces melt viscosity, increases flow length, and lowers notched impact. The grade is therefore unsuitable for cold-temperature snap-fit components or brackets that must survive drop tests at -30°C. The 500 series, with notched Charpy values of 28–36 kJ/m² at 23°C, is preferred for luggage shells, motorcycle side panels, and power-tool housings subjected to impact. Compared with Toyolac 700 series, 300-325 has lower heat resistance and should not be specified for continuous load-bearing service above 80°C. If heat resistance above 90°C under load is required, a 700-series or heat-resistant ABS is substituted. The lower melt viscosity of 300-325 also reduces plastication energy, but it increases the risk of drool at open nozzles and should be processed with a positive shut-off nozzle if barrel temperatures exceed 230°C.

Relative to flame-retardant ABS grades, 300-325 is not inherently flame retardant. It should not be used near unshielded electrical arcs or in applications requiring UL 94 V-0 at 1.5 mm. Compared with PC/ABS blends, 300-325 offers lower density and easier processing at lower melt temperatures, but its ductile-brittle transition temperature is higher; PC/ABS is required where low-temperature ductility below -10°C is specified. In chemical resistance, the grade resists aqueous acids, alkalis, and mineral oils at room temperature, but it is attacked by ketones, esters, and aromatic hydrocarbons. Stress-crack resistance should be validated using ISO 22088-3:2006 bent-strip tests on specimens with the same orientation and residual stress as the production part. Contact with amine-based thermal stabilizers in external packaging is not recommended because amines can induce stress cracking on stressed surfaces.

At incoming quality control, 300-325 lot acceptance is usually based on melt volume-flow rate, notched Charpy impact, and colour. A melt-flow shift of more than 10% from nominal is enough to alter fill imbalance in multi-cavity tools and should trigger barrel-temperature or hot-runner compensation. Continuous production of dark-colored parts can show batch-to-batch colour drift above ΔE*ab 0.5 if regrind ratio exceeds 20% by weight. For European Union electrical and electronic equipment, compliance is normally covered by the supplier’s REACH and RoHS 2011/65/EU declaration; specific lot certificates should be obtained. Food-contact status for 300-325 is not automatically assigned, and users must request a letter of assurance under 21 CFR 180.22 or 177.1020 where applicable. Published data for this specific configuration is limited in the areas of ultrasonic welding and laser transmission welding; weld factor validation should be performed on production-scale parts. The grade is not recommended for continuous outdoor exposure without UV stabilization, because unpigmented ABS yellows and embrittles after weathering.