Toray Industries Toyolac 100, referenced in procurement documents as Toray ABS 100, is an unfilled general-purpose acrylonitrile-butadiene-styrene injection-molding grade. The product consists of a continuous styrene-acrylonitrile copolymer phase with dispersed polybutadiene-rich rubber particles; this structure is produced by emulsion grafting of SAN onto polybutadiene latex followed by compounding with separately polymerized SAN. The resulting morphology is responsible for the balance of melt flow, surface hardness, toughness, and dimensional stability seen in thin-wall parts. Typical density is 1.05 g/cm³ under ISO 1183-1:2019, and melt mass-flow rate is 35 g/10 min at 220 °C and 10.0 kg under ISO 1133-1:2022. Tensile yield stress on type 1A specimens tested to ISO 527-2:2012 is approximately 50 MPa. Flexural modulus under ISO 178:2019 is approximately 2500 MPa. Notched Charpy impact at 23 °C under ISO 179-1:2010 is approximately 20 kJ/m². Heat deflection temperature at 1.80 MPa under ISO 75-2:2013 is approximately 85 °C. Rockwell hardness R-scale under ISO 2039-2:2006 is approximately R-110. The preceding values are representative published typical values and do not constitute a lot-release specification; physical property certification for the specific color and batch must be read from the manufacturer’s certificate of analysis.

The grade is supplied as pellets for injection molding; natural, black, and custom colors are available. The 100 designation identifies a high-flow, general-purpose position in the Toyolac family. It is normally selected when the part design includes wall thicknesses below 2.0 mm, multiple ribs, or screw bosses where filling pressure must be kept low. The melt fluidity allows the material to fill thin sections with moderate injection pressures, but the reduced rubber-phase volume lowers notched impact relative to higher-numbered Toyolac grades. In parts with sharp corners, metal inserts, or subzero impact requirements, the grade-design boundary must be reviewed because the high-flow morphology is not the optimum choice for maximum energy absorption.

What Restricts the Production Molding Window for Toyolac 100?

For injection molding, the upper processing boundary is controlled by polybutadiene degradation, not by the glass transition of the SAN matrix. Melt temperatures of 200 °C to 250 °C are typical, with the nozzle at 230 °C to 245 °C. Barrel profiles often start at 190 °C in the rear zone and increase to 230 °C in the metering zone. At melt temperatures above 260 °C, the polybutadiene domains undergo crosslinking and release volatile degradation products, producing yellow-brown streaking, surface splay, and deposit accumulation in vents. In hot-runner molds, local shear heating may exceed the setpoint; production logs from valve-gated hot-runner systems show gloss loss and discoloration when material stagnates in manifold dead spots at 255 °C for longer than 5 min. The lower processing boundary is defined by short shots and weld-line weakness because the melt viscosity increases as temperature decreases. Mold-surface temperature is normally 40 °C to 70 °C. Lower mold temperatures increase sink marks in thick sections and can produce visible flow lines; higher mold temperatures improve knit-line strength but extend cycle time and increase shrinkage variation across the part.

On reciprocating-screw injection machines, the material processes through general-purpose screws with 20:1 to 24:1 L/D ratio and compression ratio of 2.0:1 to 2.5:1. Machines in production tend to use clamp force between 1500 kN and 4500 kN depending on projected area; the specific clamp force should be calculated from cavity pressure and not from prescribed tonnage alone. Injection velocity at the screw assist cylinder is commonly set at 60 mm/s to 120 mm/s for thin-wall parts. Very high injection velocity can trigger jetting if a round submarine gate enters an open cavity, creating a visible worm-like surface defect that cannot be eliminated by packing pressure. The countermeasure is to use a fan, tab, or edge gate, reduce gate-land length, or lower injection speed below 150 mm/s through the gate. Hold pressure is adjusted to avoid sink marks and maintain dimensional control; typical hydraulic hold-pressure levels are 60–80 % of peak injection pressure, but actual values should be established from cavity-pressure sensor data and part-weight checks.

Silver streaking observed in Toyolac 100 appears either as diffuse silver-white marks from moisture or as yellow-brown marks from thermal degradation. Moisture streaks are distributed across the part surface and diminish after dehumidified drying; degradation streaks are localized near gates or hot-runner stagnation points. Splay from wet pellets can be prevented by maintaining residual moisture below 0.1 %. Gate blush occurs when shear heating at the gate land raises the local melt temperature beyond the degradation threshold. If gate blush appears, the gate cross-section should be opened before melt temperature is increased; this prevents false correction of a viscosity problem by degrading the material further. The grade is often molded with back pressure of 0.5 MPa to 2.0 MPa and screw surface speed below 100 mm/s to limit shear heating. Excessive back pressure or screw speed can raise melt temperature by 10 °C to 20 °C above the barrel setpoint in production, which is relevant when the barrel is already near 240 °C.

Drying and Regrind Boundaries in Unfilled ABS Processing

Toyolac 100 should enter the plastication unit with residual moisture held below 0.1 % by weight. Pellets exposed to ambient air with relative humidity above 60 % for more than 2 h are typically dried in a dehumidified-air hopper dryer at 80 °C for 3–4 h. Drying temperatures above 95 °C can soften pellets, promote sticking, and reduce feed uniformity. The dryer dew point should be below -30 °C; convective hot-air dryers are generally insufficient in high-humidity production rooms because they do not remove moisture to the same degree. As a stochastic failure pattern, wet material produces random bubble-like splay on the part surface and may reduce tensile elongation at weld lines. Overdrying is more often associated with pellet fusion than with property loss in this grade, but fused pellets can cause feed-bridging in the hopper and screw starvation.

Regrind from sprues and runners can be blended at 20 % to 30 % in non-plated parts. In electroplating applications, regrind is usually excluded because oxidized rubber particles from prior heat history create surface pits and plating adhesion defects. Regrind above 30 % can shift melt-flow rate and increase black speck contamination; the fine fraction should be screened with 4 mm or smaller perforated screens before blending. Each reprocessing pass increases the thermal history of the polybutadiene phase, so regrind material that has been through more than 3 passes should be evaluated for impact retention and color stability before use.

Applications for Toyolac 100 in production include electrical-equipment housings, small appliance fascia, office-machine chassis covers, consumer-electronics front panels, and general industrial knobs and connectors. These parts are selected because the grade develops a hard surface and reproducible dimensions while filling thin ribs and bosses. The same material can be electroplated after ABS-specific etching in chromic-sulfuric or chromium-free colloidal activation systems. Typical electroplated Cu/Ni/Cr layers on Toyolac 100 show adhesion measured by thermal-cycle or strip-pull tests; published data for this specific configuration is limited outside customer specifications, but adhesion is process-dependent and must be qualified with the plating line’s etch time and temperature. Painted or coated surfaces are supported after corona or plasma treatment raises surface energy. Unpainted Toyolac 100 is not stabilized for prolonged outdoor UV exposure; natural and light-colored parts yellow when exposed to sunlight, and surface gloss loss occurs. The grade is therefore intended for indoor components, partially covered industrial parts, or painted assemblies where the coating intercepts UV.

Comparative Position of Toyolac 100 Against Toyolac 300 and Toyolac 520

The Toyolac series uses grade numbering to reflect the performance placement within unfilled ABS. In comparison with Toyolac 300, Toyolac 100 has a higher melt-flow rate and a lower notched-impact value because the dispersed rubber-phase volume is smaller. The consequence is faster mold filling and reduced cycle time in thin-wall parts, but lower energy absorption in notched or low-temperature impacts. Toyolac 520 is positioned at the higher-impact end; it carries a larger rubber volume fraction, lower melt-flow rate, and significantly higher notched Charpy impact. The table below compiles representative typical data from public technical literature for these three grades under identical test methods. The values are not lot-release specifications and should not be used for certificate-of-analysis acceptance criteria.

The melt-flow and impact columns reveal the central trade-off: Toyolac 100 offers roughly 3 times the melt-flow rate of Toyolac 520 while providing approximately 50 % of its Charpy notched impact. In thin-wall electrical enclosures with limited drop-impact requirements, the 100 grade is preferable. In power-tool housings or structural brackets with sharp notches and low-temperature drops, the higher rubber grades are more appropriate. If an application demands both high flow and high impact, a PC/ABS blend or a redesign increasing gate size and wall thickness should be evaluated instead of overreaching the mechanical limits of Toyolac 100.

For fatigue-sensitive applications, design should incorporate stress concentration factors at gate scars and knit lines because notched Charpy is not a direct predictor of fatigue. Repeated flexural loading under ISO 178:2019 is not adequate for fatigue; cyclic tests such as ASTM D7791 may be required. Published data for Toyolac 100 under high-cycle fatigue is limited; proportional limit values in uniaxial tensile tests are more reproducible. Creep and stress relaxation are relevant above 50 °C. In a design operating at 60 °C, ABS grades including Toyolac 100 show time-dependent strain; metal screw bosses and snap-fits can lose clamping load over time. Permanent load-bearing parts should use creep data from ISO 899-1:2017 or redesign with reduced stress below the proportional limit. The grade should not be used for continuous load-bearing service above 60 °C without derating the allowable stress and volume.

For high-gloss cosmetic surfaces, process conditions influence gloss more than grade choice. Trials on polished tools show that mold surface roughness below Ra 0.1 µm is required to produce consistent gloss with Toyolac 100. Lower melt temperature and higher mold temperature improve gloss but may increase cycle time. In scratch-prone areas, hardness is not a guarantee; scratch resistance is determined by surface topography and additives rather than by hardness alone. If appearance is critical, texture selection should be matched to part geometry and gate location because gloss variation across a part is more visible in dark colors than in natural or white.

Compliance status for unfilled Toyolac 100 typically includes RoHS Directive 2011/65/EU and REACH SVHC screening for production lots in natural or black. The standard grade is rated UL 94 HB at 1.6 mm; it is not flame retarded and should not be specified for V-2 or V-0 electrical enclosures. Chemical resistance follows general ABS limits. The material resists aqueous acids, alkalis, and many polar solvents at low stress, but it is not resistant to strong oxidizing acids, ketones, esters, chlorinated solvents, or continuous immersion in methanol and ethanol. Molded parts exposed to acetone, ethyl acetate, or methylene chloride may undergo environmental stress cracking. In metal-insert molding, preheating inserts to 80 °C to 120 °C reduces residual stress concentration around the insert and lowers the probability of stress cracking. This grade is an electrical insulating material; relevant electrical property test methods are IEC 62631-3-2:2016 for volume and surface resistivity and IEC 60112:2020 for comparative tracking index, but lot-specific values should be confirmed for safety-critical components.

For dimensional calculations, typical coefficient of linear thermal expansion for Toyolac 100 is approximately 7–10 × 10⁻⁵ K⁻¹ under ISO 11359-2:2021. This range is used in multi-material assemblies with polycarbonate or metal inserts because differential thermal expansion can loosen press fits or increase internal stress over large temperature excursions. Published data for specialty colors, laser-marking additives, or anti-static concentrates in Toyolac 100 is limited; dark colorants and fillers can alter mold shrinkage, heat deflection temperature, and melt-flow rate. When critical dimensions are involved, mold design should rely on cavity-pressure transducers and dimensional capability studies rather than solely on datasheet shrinkage ranges.