Permanent Orange GR is assigned C.I. Pigment Orange 13, C.I. 21110, a disazo pyrazolone pigment supplied as a dry powder. The pigment is evaluated in downstream applications as a colorant, not as a formulated additive. Application fitness is determined by the processing window of the host matrix, dispersive energy input, and the regulatory status of the finished article.

Why Does Solvent-Borne Flexo Ink Demand a Narrow Primary Particle Distribution for C.I. Pigment Orange 13?

Solvent-borne flexographic and gravure inks for surface-printed or laminated flexible packaging disperse Permanent Orange GR into a co-solvent blend of ethyl acetate and n-propanol, with nitrocellulose and polyurethane resin as the film formers. The pigment is pre-wet in a high-speed dissolver for 15–20 min at a tip speed of 20–25 m/s to break down loose aggregates before bead milling. The slurry is then transferred to a horizontal bead mill charged with 0.8–1.0 mm yttria-stabilized zirconia beads; mill chamber temperature is held below 55 °C to reduce solvent evaporation and protect the disazo pyrazolone chromophore from thermal shade drift. Fineness of grind is measured with ISO 1524:2020 on a 100 μm grindometer; a reduction for laminated film should read below 10 μm, while opaque surface whites may tolerate a slightly coarser grind if the anilox line screen is below 400 l/cm. Pigment loading is not a fixed formula constant; a solvent-based flexo millbase is commonly prepared at 30 wt% pigment on total millbase mass, and the final press-ready ink is reduced to a pigment content between 8 wt% and 12 wt% depending on print density, film thickness, and opacity target. Press viscosity is set with a 4 mm DIN flow cup under ISO 2431:2019; target values vary by deck, speed, and cell depth of the laser-engraved ceramic anilox roll. Cross-cut adhesion on corona-treated polyethylene or polyester is checked to ISO 2409:2020 after a standard lamination or surface-print trial. For food packaging, the pigment is used on the non-food-contact side or in an adhesive-laminated construction unless migration testing under Regulation (EC) No 1935/2004 and EN 1186 demonstrates that the pigment does not transfer through the substrate. Retained solvent in printed reels is quantified by ISO 11890-2 gas chromatography because high residual ethyl acetate contributes to odour in the sealed pouch. The EuPIA Good Manufacturing Practice framework for printing inks applied to the non-food-contact side of packaging is the reference hygiene protocol for this application.

Table 1: Standard test methods referenced in application evaluation.

In aqueous corrugated flexographic and multi-wall sack printing, Permanent Orange GR is dispersed into an ammonia-stabilized acrylic emulsion, with the dry pigment first wetted by a non-ionic surfactant or a low-foam dispersant. The oil absorption value determined under ISO 787-5:2019 is used to estimate the dispersant demand before milling. A millbase is prepared at 35–40 wt% pigment on total millbase mass in a cooled horizontal bead mill; the final corrugated ink is reduced with acrylic letdown resin and water to a pigment content of 7–10 wt% on total press-ready mass. pH is maintained between 8.8 and 9.5 because lower pH can reduce resin stability, while pH above 10 can trigger shade dulling and viscosity drift in disazo pyrazolone pigments. Viscosity at 25 °C is set via ISO 2431:2019 with a 6 mm DIN cup; the target depends on the anilox roll cell volume and the flute profile of the corrugated board, so each press set-point is established by a standard drawdown series. Dry film abrasion on kraft and white-top liners is evaluated with ASTM D5264 using a Sutherland rub tester. Compliance for the packaging substrate is anchored to Directive 94/62/EC Article 11, which limits the sum of lead, cadmium, mercury, and hexavalent chromium to 100 mg/kg at packaging weight. For printed corrugated items intended for toy packaging or lightweight consumer goods, the finished article may additionally be assessed under EN 71-3:2019 + A1:2021 for migration of specific elements. The pigment itself is not the sole determinant of compliance; the acrylic binder, defoamer, and wax slip additive all contribute to the final chemical inventory.

When C.I. Pigment Orange 13 Is Evaluated for Alkyd Air-Dry Industrial Enamels

Long-oil alkyd air-dry enamels and machinery paints incorporate the pigment where a yellow-shade orange must withstand intermittent industrial exposure rather than continuous exterior weathering. Pigment loading in the finished paint is typically between 4 wt% and 10 wt% on total paint mass, with the exact level derived from hiding-power and colour-strength evaluations against ISO 6504-3. The pigment is dispersed in a high-speed dissolver with alkyd resin and mineral spirits, then passed through a vertical or horizontal bead mill to a fineness below 15 μm under ISO 1524:2020. Drying is a critical conflict in this matrix because the pigment surface can adsorb cobalt and zirconium drier metals, shifting through-dry times unpredictably. Consequently, cobalt and zirconium drier ratios are re-optimized after pigment addition using ASTM D1640/D1640M-14 rather than inherited from a clear alkyd base. The painted panel or casting is tested for through-dry, tack-free time, and hardness development. Light fastness is screened with ISO 16474-2:2013 xenon-arc exposure; a disazo pyrazolone pigment of this class is not expected to match quinacridone or DPP durability, so the formulation is limited to applications where colour change above a specified delta E is acceptable. Where exterior gloss and colour retention are mandatory, an ultraviolet absorber or a more lightfast pigment is required. Volatile organic compound compliance is governed by Directive 2004/42/EC for architectural and industrial maintenance coatings. For industrial equipment paint sold into electrical enclosure applications, additional heavy-metal restrictions under Directive 2011/65/EU Annex II may apply to the cured film at the homogeneous-material level.

PVC Extrusion and Injection Compound Process Limits

Flexible and rigid PVC compounds use Permanent Orange GR where a mid-orange tone is required in thin-gauge extruded sheet, injection-moulded closures, and cable jacket formulations. The pigment is incorporated as a dry powder or a plasticizer pre-paste in a high-intensity hot mixer at 80–90 °C together with PVC resin, plasticizer, heat stabilizer, and lubricant. Typical use concentrations are 0.5–1.5 phr in flexible PVC and 0.2–0.8 phr in rigid PVC; higher loadings raise melt viscosity and can generate pigment agglomerates if the shear history is insufficient. The dry blend is processed on a parallel twin-screw compounder or a two-roll mill before final extrusion or injection moulding. Melt temperature at the die or nozzle is monitored with an infrared pyrometer and kept within the heat stability window stated by the pigment supplier; published production-scale data for disazo pyrazolone pigments in rigid PVC extrusion above 200 °C are limited, so plant-scale trials must verify shade stability and gas-yellowing resistance before full production. Colour measurement on extruded sheet or moulded plaques follows ISO 7724-3:2019; heat stability is assessed by delta E and visual inspection after 10–15 min oven ageing at 180 °C in a forced-air laboratory oven. Compliance for electrical and electronic PVC parts is assessed under Directive 2011/65/EU Annex II as amended by (EU) 2015/863, with lead, cadmium, mercury, hexavalent chromium, PBB, and PBDE limits applied at the homogeneous-material level. When the pigmented PVC article is marketed as a toy or childcare item, EN 71-3:2019 + A1:2021 governs element migration, and the plasticizer system must independently satisfy REACH restrictions. The pigment alone does not determine compound compliance; barium-zinc or calcium-zinc stabilizer packages and flame-retardant additives dominate the hazardous-substance profile.

Table 2: Compliance checklist matrix referenced across downstream applications.

Textile pigment printing pastes exploit the insolubility of C.I. Pigment Orange 13 in water and the absence of a reduction-oxidation fixation stage. The pigment is dispersed into an aqueous paste containing a self-crosslinking acrylic binder, a synthetic thickener such as an acrylic acid copolymer, and a humectant. Pigment content in the ready-to-print paste is typically between 2 wt% and 8 wt% on total paste mass; binder-to-pigment ratio is adjusted by dry film fastness testing because an insufficient binder content produces crocking failure. The paste is applied by rotary screen printing or flatbed screen printing onto woven cotton or polyester-cotton knits, followed by drying and fixation at 150 °C for 3–5 min in a forced-air stenter frame. Cure temperature and dwell time are critical; under-curing lowers wash fastness, while over-curing can yellow the binder film. Washing fastness is tested according to ISO 105-C06:2010 for domestic laundering, and rubbing fastness is tested with ISO 105-X12:2016. Light fastness on textile is assessed under ISO 105-B02:2014 xenon-arc exposure. Compliance for textile articles is formulated against OEKO-TEX Standard 100 Annex 4 limits for harmful chemicals and the brand-level ZDHC MRSL where relevant. This pigment class is unsuitable for discharge printing processes because reducing agents such as zinc formaldehyde sulphoxylate or sodium sulphoxylate formaldehyde can cleave the azo chromophore and destroy the shade. The printed fabric is normally used in fashion accessories, decorative home textiles, and promotional apparel where high chromaticity is required and the orange shade is retained after repeated washing.

A Vulcanization Rheometry Check Is Required Before C.I. Pigment Orange 13 Is Qualified in Sulphur-Cured Rubber

Rubber calendering and extrusion grades use Permanent Orange GR when a non-bleeding organic orange is needed in sulphur-cured natural rubber, styrene-butadiene rubber, or EPDM compounds. The pigment is added at the internal mixer stage after polymer mastication and before carbon black or mineral fillers to maximize dispersion. Typical use concentration is 0.5–2.0 phr; higher loading can increase compound Mooney viscosity and lengthen mixing cycles. A two-roll open mill is used for final pigment dispersion and sheeting after a Banbury-type internal mixer; mill roll temperature is kept below 80 °C to prevent pigment agglomeration and surface bloom. Vulcanization kinetics are influenced by the pigment surface, so the cure package, particularly thiazole and sulphenamide accelerators, is adjusted only after a rotorless cure meter test according to ASTM D5289. The minimum torque, maximum torque, and scorch time are compared against an unpigmented control compound. Finished rubber sheets are tested for shade change and migration under ISO 3865:2017. Compliance for consumer rubber goods is reviewed against REACH Annex XVII restricted substances and, for food-contact seals, against Regulation (EC) No 1935/2004 and EU 10/2011 only if a positive migration assessment is completed. Published production-scale data for this pigment in all rubber matrices are limited; the exact cure system and stabilizer package must be validated on factory mixing and vulcanizing lines because short scorch times are a known failure mode in organic-pigmented rubber batches. The dispersant and processing oil must be included in factory control charts because they alter hue direction and bloom tendency.