TECHNICAL GUIDE · PR122 PIGMENT & FORMULATION

What Is PR122? Pigment Red 122 in Aqueous and UV Inkjet Inks

PR122 is a quinacridone pigment used for magenta inkjet colour. Its performance depends on the selected grade, dispersion vehicle and complete ink formulation.

By AIC · Published 5 November 2026

What is PR122?

PR122 is C.I. Pigment Red 122, a quinacridone organic pigment widely used to produce magenta colour. Its chemical identity is 2,9-dimethylquinacridone, CAS 980-26-7. The Colour Index designation identifies the pigment chemistry; it does not specify a supplier’s complete commercial grade or ink formulation. [1]

Although its Colour Index name contains “Red”, PR122 is commonly selected for the magenta channel in inkjet colour sets. The printed shade, transparency and colour strength depend on the grade, dispersion and substrate. It is a particulate colourant: an aqueous PR122 dispersion contains stabilised solid particles rather than pigment molecules dissolved in water. [2]

On smaller screens, scroll the tables sideways to see every column.

Table 1. PR122 identity and formulation role
Identifier / property	Description	Practical meaning
Colour Index name	C.I. Pigment Red 122 / PR122	Identifies the colourant, not a ready-to-print ink.
CAS number	980-26-7	A chemical-identity reference; the supplied product may contain a dispersion vehicle and other components.
Chemical class	Quinacridone; 2,9-dimethylquinacridone	A defined organic pigment molecule forming solid particles. Polymer dispersants, encapsulation layers and binders are separate formulation components.
Inkjet role	Magenta pigment component	Evaluate the actual shade, colour strength and dispersion in the intended ink system.

Why the pigment grade matters

PR122 is attractive for inkjet because suitable grades combine magenta colour strength, transparency and useful durability. Manufacturers develop inkjet pigments with attention to particle design, purity and dispersion behaviour. TOYOCOLOR’s published inkjet pigment work, for example, uses PR122 to illustrate how fine-particle design affects colour strength and transparency. Its laboratory comparisons are not a universal printer-performance guarantee. [3]

A powder intended for plastics or conventional printing should not be accepted for inkjet solely because its label says PR122. Ask for the grade’s intended application, particle-characterisation method, coarse-particle control, extractable or soluble components, and batch consistency. Surface treatment and the dispersion process also affect how it behaves in the selected vehicle.

Lightfastness is an important reason to consider quinacridone magenta, but published ratings belong to a specified grade and test. One manufacturer’s inkjet-grade PR122 data sheet reports lightfastness of 7–8 in full shade and 7 in a specified reduction. These figures do not establish the service life of every PR122 print. Weathering, washing, rubbing, adhesion and chemical resistance must be assessed on the finished product. [4]

PR122 in aqueous inkjet inks

In an aqueous system, the first task is to keep the pigment dispersed throughout storage, formulation, filtration and jetting. Suitable routes include adsorbed dispersants and pigment-surface modification. Cabot’s original work on surface-modified colour pigments includes a PR122 system stabilised by chemically attached ionic groups. That supports the self-dispersed route; it does not mean untreated PR122 is naturally self-dispersing. [5]

The dispersion must remain compatible after dilution into the complete ink. Humectants, binders, surfactants, salts and pH adjustment can change colloidal interactions. Evaluate the formulation after mixing and ageing, as well as the concentrate before formulation. A low initial viscosity and an attractive particle-size average do not establish long-term reliability.

Potential aqueous applications include desktop pigment inks, paper and corrugated printing, and textile pigment inks such as DTG and DTF. Each has different finished-print requirements. Paper printing needs controlled spreading, penetration and drying. Textile printing needs a binder and fixation route suited to the fabric; wash and rub fastness cannot be assigned to PR122 alone.

For ionic or surface-modified dispersions, conductivity is a formulation-control measurement rather than a direct purity percentage. A powder-extract conductivity test and a measurement on an aqueous concentrate are different tests. Compare results only with their sample preparation, concentration and temperature stated.

PR122 in UV-curable inkjet inks

PR122 can also be used in UV-curable inkjet when the selected grade and dispersion package suit the reactive vehicle. Commercial PR122 UV pigment preparations provide a direct example of that route. The same pigment identity does not make an aqueous dispersion interchangeable with a conventional non-aqueous UV millbase. [6]

In a conventional radical-curing UV formulation, the pigment must be wetted and stabilised in the chosen monomers, oligomers and additives. Formulation changes can affect flocculation, viscosity, jetting and cured-film properties. BASF’s dispersant guidance specifically makes optimisation dependent on the pigment, dispersion medium and final let-down composition. A dispersant dosage from another pigment or vehicle is therefore a starting hypothesis, not a PR122 recipe. [7]

UV applications can include labels, packaging graphics, signs and industrial decoration. Requirements vary with the substrate and downstream use: adhesion to a film, flexibility during conversion, resistance to handling, and the required surface finish. Pigment compatibility alone does not establish package-use or other regulatory suitability.

Curing needs its own qualification

The pigment’s optical behaviour, photoinitiator response and printed-layer thickness all affect the curing process. Select and test the complete magenta formulation with the intended lamp spectrum, line speed and laydown. There is no single wavelength or exposure setting that can be assigned to all PR122 inks. Noblelight’s process guidance explains why spectral transmission and optical thickness matter to through-cure and adhesion. [8]

Report irradiance in W/cm² or mW/cm² and radiant exposure in J/cm² or mJ/cm², together with the spectral band and measurement position. Lamp electrical wattage alone does not describe the exposure received by the ink. Surface tack and through-cure should be checked separately; oxygen inhibition is an additional consideration in radical-curing systems. [8] [9]

Storage stability also includes resistance to premature polymerisation, not just resistance to pigment settling. Use the ink supplier’s specified light protection, temperature and handling conditions; aqueous dispersion storage instructions cannot simply be transferred to a reactive UV formulation. [10]

Aqueous and UV requirements compared

Table 2. The same pigment chemistry in different formulation environments
Development issue	Aqueous pigment ink	Conventional non-aqueous UV-curable ink
Dispersion vehicle	Water with compatible humectants, co-solvents and additives.	Reactive monomer/oligomer vehicle with compatible additives.
Stabilisation	Dispersant or surface-modification system that remains effective in the complete aqueous formulation.	Dispersant and surface interactions suited to the reactive vehicle and final let-down.
Print formation	Wetting, carrier removal and binder fixation appropriate to the substrate.	Wetting followed by controlled photopolymerisation, with any required pinning and final cure.
Jetting window	Viscosity, surface tension and recovery at the exact head’s operating conditions.	The same jetting evaluation, plus thermal and chemical stability of the reactive formulation.
End-use evaluation	Paper image quality or textile wash/rub performance, according to the application.	Cure, adhesion, flexibility and resistance after printing and conversion.

Where waterborne UV fits

Waterborne UV inkjet is a distinct formulation route combining an aqueous vehicle with radiation-curable components. Its existence means “water-based” and “UV-curable” are not mutually exclusive descriptions. allnex publishes a waterborne UV inkjet development framework, although its cited starting formulation uses a cyan pigment rather than PR122. [11]

A PR122-specific research example is Guan and colleagues’ UV-curable pigment/latex dispersion for textile printing. The work used polymer encapsulation and a deliberately designed aqueous system. It should not be treated as validation of a standard non-aqueous UV ink or of an AIC self-dispersed product. [12]

What should an ink maker test?

The following checklist is a proposed development framework. Acceptance limits should follow the selected printhead, formulation and finished-product requirements.

Table 3. PR122 qualification from colourant to finished print
Evaluation	What to record	Why it matters
Identity and grade	CI/CAS identity, supplier grade, treatment, pigment content and batch documentation.	Separates pigment identity from the properties of the supplied preparation.
Colour	Shade, colour strength, transparency, gamut and metamerism on the intended substrate.	A pigment name alone does not define the final colour match.
Particle distribution and filtration	Method, dilution, distribution basis, upper-tail data, filterability and coarse contamination.	A median size alone does not describe the risk to a fluid path.
Formulation stability	Particle and viscosity changes after let-down, thermal residence and storage; pH/conductivity for aqueous systems.	Checks the complete vehicle rather than only the pigment concentrate.
Jetting	Operating temperature, waveform, frequency, drop quality, sustained run and idle recovery.	Connects material measurements with actual head performance.
Finished print	Drying or cure, adhesion, rubbing, washing, light exposure and conversion as applicable.	Demonstrates performance of the whole printed construction.

Test results must remain comparable. A primary-particle measurement, a dispersed-particle D50 and a hydrodynamic average can describe different things. Keep D90, D97 and D99 labels as reported, and obtain the current batch information instead of treating a representative chart as a universal pigment specification. See the particle-size guide for more context.

AIC’s aqueous PR122 development route

AIC-Magenta Red 1015 is a carboxylic surface-modified, self-dispersed aqueous PR122 colourant with 15 wt% pigment content. Its role is to supply the colourant component for aqueous ink development. The product page brings together the supplied particle-size report, TDS, SDS and a representative batch COA.

This aqueous grade should be assessed in the complete ink with the intended binder, humectants, head and substrate. It is not presented here as a qualified conventional UV millbase. For an enquiry, specify whether the project is aqueous, non-aqueous UV or waterborne UV, alongside the printhead and final-print requirements.

Further reading: evaluating dispersion properties, printhead features and application selection, and high-viscosity ink and printhead development.

Technical references

Reviewed 5 November 2026. Supplier examples establish specific material routes and test contexts; their numerical properties are not AIC specifications. The qualification checklist is an engineering synthesis.

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