The Clariant Polyethylene Terephthalate Glycol Black 3D Printer Filament is a pigmented glycol-modified copolyester feedstock for fused filament fabrication. The base resin is a copolyester in which a portion of the ethylene glycol repeat unit is replaced by cyclohexanedimethanol, producing a polymer with suppressed crystallization and an amorphous or weakly semicrystalline morphology after cooling from the melt. The black configuration is compounded with a carbon black dispersion, and procurement records generally identify the material by polymer family, colorant package, melt flow class, and wire diameter rather than by a single alphanumeric grade code uniformly reproduced in all regional documentation. Because published data for this specific Clariant black polyethylene terephthalate glycol configuration is limited, downstream qualification should rely on lot-specific certificates of analysis and printed-coupon testing rather than on generic PETG datasheets. Nominal supply forms include filament diameters of 1.75 mm and 2.85 mm; typical diameter tolerance is ±0.05 mm with an ovality limit of ≤0.03 mm. The material is amorphous enough to provide a glass transition temperature near 78 °C and a heat deflection temperature under 0.45 MPa generally in the range of 65 °C to 70 °C.

In boundary terms, the black pigment is not a passive optical additive. Carbon black increases opacity, modifies low-shear viscosity, and can act as a mild abrasive against brass extrusion nozzles. In fused filament fabrication, direct-drive extruders with hardened steel or ruby nozzle orifices are used to limit wear. Typical deposition parameters for a 0.4 mm nozzle are nozzle setpoints from 235 °C to 255 °C, heated bed setpoints from 70 °C to 85 °C, and part cooling fan speeds restricted to 20 % to 50 % of maximum flow for overhang and small feature stability. Chamber temperatures above 45 °C may soften thin overhangs and degrade dimensional stability. Actual setpoints should be confirmed by printing a temperature tower and a Z-direction tensile bar because the carbon black masterbatch can shift the melt viscosity relative to natural polyethylene terephthalate glycol.

Applications for the black product include functional prototyping, positioning fixtures, low-volume assembly tooling, cable routing hardware, and light-shielding enclosures where ductility and resistance to warp are required. The material is not a direct substitute for polycarbonate in continuous service above 70 °C, nor for nylon in snap-fit designs requiring sustained high-cycle fatigue. It is more ductile than many black pigmented PLA compounds, emits less styrene during open-frame printing than ABS, and has lower wet-state dimensional change than unfilled nylon. Chemical exposure to ketones, chlorinated solvents, esters, and some aqueous alkaline cleaning baths can produce stress crazing; suitability must be confirmed by immersion testing under load according to the relevant ASTM or ISO chemical resistance protocol. Food-contact use is constrained by pigments and printed surface texture, not automatically granted by the base resin status.

How Does Glycol Modification Affect Interlayer Strength and Warp in Black PETG?

The cyclohexanedimethanol units in polyethylene terephthalate glycol reduce the chain regularity that drives primary crystallization in PET. During cooling from the nozzle, the black filament therefore solidifies without the sharp crystallization exotherm that creates high shrinkage in semicrystalline PET. Shrinkage is lower than in semicrystalline PET, and warp is generally lower than in ABS under the same bed conditions. However, interlayer fusion is controlled by molecular diffusion across the weld line at temperatures above the glass transition. A slow-crystallizing amorphous melt can retain sufficient open time for chain interdiffusion at the interface, but this advantage is reduced if the black pigment raises local viscosity and restricts wetting. Printed specimens must be tested in the Z direction according to ISO 527-2 or ASTM D638-14, because XY-direction tensile data do not capture the limiting interlayer strength. The anisotropic behavior is a product of the FFF process path and is not eliminated by the copolyester chemistry alone.

The reduction in warp relative to ABS is operationally relevant: ABS can require heated chamber temperatures of 70 °C to 80 °C and controlled cooling to prevent corner lifting, whereas black PETG can often be printed on a 70 °C to 85 °C heated bed with chamber temperatures below 45 °C. The trade-off is a lower heat deflection temperature. Where the part sees continuous heat soak above 70 °C, the load-bearing capability of black PETG can fall more rapidly than that of polycarbonate or polysulfone, so design verification should include short-term creep at the maximum service temperature.

Drying, Melt Filtration, and Extrusion Boundaries for Black PETG Filament

Moisture control is among the strongest determinants of black PETG melt quality. At 50 % relative humidity, polyethylene terephthalate glycol filaments can pick up surface and absorbed moisture within hours. Printing wet material hydrolyzes ester linkages at melt temperature, lowers molecular weight, creates gas splay, and reduces interlayer strength. Pre-drying in a desiccant dryer at 65 °C for 4 h to 6 h with a dew point of −40 °C or better is the standard boundary. Drying above 65 °C risks deformation of spooled filament under winding stress. A moisture target below 200 ppm is commonly applied to PETG extrusion and FFF feedstocks; lot-specific certificate of analysis should confirm the actual value. Unopened spools should be stored at 20 °C to 25 °C and 30 % to 50 % relative humidity in sealed barrier bags with desiccant; once opened, hot-air drying should be used before printing if exposure exceeds 8 h.

Filament production benefits from vented twin-screw compounding with L/D ratios of 36:1 to 52:1 and a vacuum vent to pull residual moisture from the melt. Melt filtration after compounding is typically set at 20 μm or finer to remove carbon black agglomerates. Agglomerates above 20 μm can create diameter spikes, nozzle clogging, and poor surface finish in a 0.4 mm nozzle. Carbon black masterbatch dispersion should be verified by pressure rise across a screen pack or by microscopic film analysis; batch-to-batch variation in pigment dispersion can shift melt viscosity even if the resin lot remains unchanged.

When Carbon Black Masterbatch Loading Is Increased Beyond Cosmetic Levels

Increasing carbon black concentration to improve opacity changes the rheological and mechanical response of polyethylene terephthalate glycol. At low shear rates, carbon black agglomerates can form a network that raises viscosity. In filament extrusion, this can lower melt pump stability and produce higher head pressure. In FFF, highly loaded black PETG may require nozzle temperatures near the upper end of the 235 °C to 255 °C window and may still exhibit reduced weld ductility if the pigment restricts interlayer diffusion. For practical black filament production, carbon black content is generally held below 2.0 % by weight to balance opacity, melt processability, and mechanical toughness. Published data for the exact Clariant black loading is limited; the masterbatch formulation may vary by region and should be confirmed with the supplier.

The carbon black surface absorbs ultraviolet radiation and can slow surface embrittlement during intermittent outdoor exposure, but black PETG is not automatically a UV-stabilized grade for long-term outdoor service. Tensile impact retention after accelerated weathering should be tested under ISO 4892-2 or ASTM G154. The black product should also not be confused with impact-modified or glass-fiber-filled PETG compounds unless the certificate of analysis explicitly lists an impact modifier or filler package.

A systematic comparison against adjacent polymer classes clarifies the positioning. The table below uses representative property envelopes for black PETG filament, amorphous PET, and ABS. The values are class-level ranges and may not represent the exact Clariant certificate of analysis; they should be used only for preliminary material screening.

The comparison demonstrates that black PETG occupies a lower-temperature ductile envelope: it exceeds ABS in elongation under tensile loading but does not match ABS in heat deflection temperature. Against amorphous PET, black PETG offers much higher elongation and lower tendency to catastrophic brittle failure, but amorphous PET may display higher tensile modulus. Those trade-offs matter when selecting the product for non-load-bearing housings versus load-bearing fixtures in warm environments.

Regulatory compliance cannot be assumed from the base polymer class alone because the black masterbatch and any processing additives are separate components. The matrix below summarizes the verification boundaries that should be checked against the Clariant lot-specific documentation.

The most common processing failure with black PETG is feeding inconsistency caused by spool winding tension or by diameter variation beyond ±0.05 mm. Excessive tension can ovalize the filament at the feed drive; under-driven or over-driven tension in direct-drive extruders produces under-extrusion or filament stripping. The second most common issue is nozzle buildup from carbon black and partially degraded polymer when the nozzle sits idle above 250 °C for extended periods. Purge with a low-temperature purge compound or natural PETG between production runs. Continuous printing of black PETG at the upper nozzle temperature for more than 8 h may progressively darken or degrade the melt if the hot-end residence time is prolonged and the filament is not adequately dried; periodic cold pulls and nozzle cleaning are required.