Fast Scarlet BBN (C.I. Pigment Red 22, CAS 6448-95-9, relative molecular mass 426.42) is a monoazo Naphthol AS pigment supplied as a scarlet powder with high colour strength in solvent-borne, oil-based and certain aqueous dispersion systems. The application sections below are restricted to established downstream processing routes for this grade and do not extrapolate performance to non-analogous pigment classes. Where published data for a specific processing configuration is limited, the limitation is stated explicitly rather than bridged with generic pigment behaviour.

Nitrocellulose gravure ink concentrates and ketonic cosolvent limitations

Dispersion viscosity in nitrocellulose-based gravure inks is the primary variable governing colour strength development, because the pigment’s nitro-substituted aromatic ring can interact with basic resin amines and raise yield stress if the premix is under-wetted. Compliance for solvent-borne liquid inks is verified against EN 71-3:2019+A1:2021 when printed articles fall within the toy-material scope, and against REACH Annex XVII Entry 43 for azo nitrogen cleavage products; free aromatic amines after reductive cleavage must remain below 30 mg/kg as determined by HPLC-DAD. In nitrocellulose gravure ink, the pigment loading is 5–10 wt% of total liquid ink; flexographic solvent inks formulated with polyurethane/NC blends require 8–12 wt% to reach comparable optical density on low-absorptive films. Dispersion is conducted by first wetting the dry pigment or presscake in a mixture of ethyl acetate, isopropanol and propylene glycol monomethyl ether at a resin-to-solvent ratio of 1:2.5, followed by two passes through a horizontal bead mill charged with 0.8–1.0 mm yttria-stabilized zirconia beads, with chamber residence time of 8–12 min per pass and outlet temperature not exceeding 45°C. The let-down phase adds nitrocellulose, polyurethane and wax dispersion; finished ink is adjusted to 18–22 s flow time in a 4 mm DIN 53211 cup. Terminal printed articles include non-food-contact flexible packaging overwrap films, paper sacks, laminated labels and coated carton exteriors where the print is outside a functional barrier validated under Commission Regulation (EU) No 10/2011. The operational boundary with ketonic cosolvents above 5 wt% of total solvent is not well characterised in published technical datasheets for C.I. Pigment Red 22; adopting higher ketone concentrations requires a bench-scale dispersion trial before production launch.

Where waterborne styrene-acrylic binders require a scarlet masstone without heavy-metal pigments, Fast Scarlet BBN is dispersed into the millbase at 15–25 wt% pigment in a high-gloss grinding vehicle, then reduced to 0.8–3.0 wt% of total liquid paint. Compliance under EU Directive 2004/42/EC Annex II for decorative coatings is achieved because the pigment concentrate is supplied as a solvent-free presscake or dry powder and the final coating meets the specified VOC ceiling; the dry film is evaluated for lightfastness using ISO 16474-2:2013 and for adhesion to cementitious substrates using ISO 4624:2023. High-speed disperser conditions of 7–10 m/s tip speed are maintained for 20–30 min until a Hegman gauge reading of 5–6 µm is reached; the premix typically contains pigment, polyacrylate ammonium salt dispersant at 0.5–1.0 parts, defoamer and propylene glycol, with pH held at 8.0–9.0 to stabilise pigment-wetting and avoid shock seeding. The millbase is let down with an anionic styrene-acrylic latex of glass transition temperature 0–15°C, coalescent at 2–4 wt% of latex solids, and a rheology modifier to a Stormer viscosity of 85–95 KU. Terminal end-product types are interior trim enamels, waterborne industrial primers, light-exterior wood coatings and architectural tinting pastes supplied to point-of-sale dispensers. The operational boundary is exterior full-sun exposure: C.I. Pigment Red 22 does not retain tinctorial stability in pale shades beyond 6–12 months of continuous weathering in subtropical sites, and published data for accelerated weathering of this specific binder configuration is limited.

What governs heat stability when Fast Scarlet BBN is dispersed in rigid and plasticised PVC?

Thermal stability in PVC compounds is governed by the interaction of the pigment’s nitro group with hydrogen chloride generated during processing, rather than by primary particle size alone. In flexible PVC cable compounds, the pigment addition is 0.2–0.8 phr based on PVC resin; in rigid PVC profiles and sheets, the addition is 0.05–0.3 phr, with lower levels preferred because the pigment’s molar absorption can interfere with tin stabiliser reversion at processing temperatures above 170°C. Compliance for electrical and electronic cable applications is assessed against RoHS 2011/65/EU Annex II concentration limits of 0.1 wt% lead, 0.01 wt% cadmium and 0.1 wt% mercury in homogeneous material, and against EN 50575:2014/A1:2016 reaction-to-fire declarations when the sheath is part of a construction cable. Processing is performed by first dry-blending PVC, plasticiser, stabiliser and pigment in a hot mixer to 70–90°C, then fluxing on a two-roll mill at 160–170°C for 5–8 min; the fused hide is calendered or extruded with melt temperatures held below 180°C to prevent a shift in hue toward a duller red. Finished product types include flexible cable sheathing, floor tiles, synthetic leather, rainwear film and decorative rigid trim. A critical operational boundary is replacement of tin mercaptide stabilisers with calcium-zinc systems: the lower chloride scavenging capacity of calcium-zinc stabilisers can cause shade drift at addition levels above 0.5 phr unless epoxy co-stabiliser is increased by 2–3 phr.

In sulphur-crosslinked rubber goods, injection of the pigment after carbon black dispersion reduces shear-induced aggregate breakdown and maintains colour value in high-structure SBR compounds. Compliance is verified against ASTM D3182-15 for mixing procedures and against ZDHC MRSL V3.0 where the rubber article is destined for footwear under brand restricted substance lists; the pigment must not contain free primary aromatic amines above the method detection threshold of 20 mg/kg. Fast Scarlet BBN is incorporated at 0.5–2.0 phr for SBR and NBR compounds, and at 0.3–1.0 phr in natural rubber latex colours where lower loadings limit pinhole formation in dipped films. A single-stage Banbury mixing sequence is used, with a starting temperature of 60–80°C, carbon black and plasticiser added in the first phase, and pigment added with zinc oxide and stearic acid before the ram is lifted at 110–125°C; curatives are then dispersed on a two-roll mill at 60–70°C before vulcanisation at 140–160°C for 8–20 min depending on section thickness. Terminal rubber products include footwear soles, rubber mats, hose covers and expansion joints. The operational boundary is peroxide curing of EPDM above 170°C: the nitro-substituted chromophore can interfere with peroxide decomposition, producing uneven crosslink density and a shade shift toward a brownish red; published data for this specific pigment in dicumyl peroxide systems is limited.

When rotary-screen textile printing pastes impose rheological constraints on pigment dispersion

If a rotary-screen textile print paste is specified without lead chromate pigments, the rheology of the aqueous binder-thickener matrix becomes the controlling variable because the pigment’s particle size distribution must remain stable against gravitational sedimentation during screen dwell. Compliance under OEKO-TEX Standard 100 requires that the final print on cotton or polyester meet residue limits for extractable heavy metals and that no banned azo cleavage amines exceed 30 mg/kg under EN ISO 14362-1:2017; the paste formulation must also conform to ZDHC MRSL V3.0 for binder systems and thickeners. Fast Scarlet BBN is incorporated at 1–3 wt% of the aqueous print paste, with the binder added at 8–12 wt% solids and a synthetic thickener at 1.5–2.5 wt% to achieve a viscosity of 8,000–15,000 mPa·s on a Brookfield RV spindle 6 at 20 rpm. The paste is prepared by dispersing the pigment as a predispersed aqueous paste with propylene glycol and anionic surfactant, then mixing under a high-shear disperser for 15–20 min; the paste is printed through rotary screens of 80–125 mesh and dried in a stenter at 120–130°C, followed by crosslinking at 150–170°C for 3–5 min. Terminal products include printed apparel, home textiles and promotional tote bags where the binder film provides acceptable crock fastness under ISO 105-X12:2016. An operational boundary is high pigment-to-binder ratios above 1:6: dry crock falls below grade 4 and the additive use of melamine-formaldehyde crosslinkers can release free formaldehyde above 16 mg/kg, requiring scavenger addition.

Polyolefin masterbatch extrusion and the 160°C dwell threshold

Compliance for polyolefin masterbatches is verified by EN 71-3:2019+A1:2021 for soluble elements in toys, by REACH Annex XVII Entry 43 for aromatic amines, and by Commission Regulation (EU) No 10/2011 only when a functional barrier can be demonstrated; direct food-contact use of C.I. Pigment Red 22 is not established and published data for specific migration under the regulation is limited. Masterbatch manufacturing uses a co-rotating twin-screw extruder with 40:1 L/D ratio and a dispersive kneading block section, barrel temperatures zoned from 140°C to 180°C, screw speed 300–600 min^-1, and a pigment loading of 20–40 wt% in a polyethylene or polypropylene carrier; the masterbatch is then let down at 25:1–100:1 to yield a final pigment concentration of 0.05–1.0 wt%. Injection moulding of finished articles is conducted with melt temperatures not exceeding 190°C and cumulative residence time below 8 min, because the nitro-substituted monoazo chromophore undergoes thermal degradation above this threshold, shifting the shade to a duller red and generating surface plate-out on mould vents. Terminal polyolefin products include non-food packaging crates, containers, closures, housewares, stationery and industrial spools. The processing limit is rigorous: at melt temperatures of 200°C or higher, colour strength can drop by 5–10% per pass, and published data for the exact degradation kinetics in multi-pass regrind streams is limited.