Phthalocyanine Green (PG7) Pigment – High-Performance Pigment for Paints & Inks

Phthalocyanine Green (PG7), designated as Pigment Green 7 (C.I. 74260), is a high-performance synthetic organic pigment known for its exceptional color brilliance, stability, and versatility. Widely used in fine arts, industrial coatings, plastics, and printing inks, Phthalocyanine Green is prized for its intense bluish-green hue, high tinting strength, and superior resistance to environmental degradation.

Origin and History

First synthesized in 1936, Phthalocyanine Green (PG7) was developed to improve Phthalocyanine Blue (PB15), discovered in 1935. Chemists identified that chlorination of the copper phthalocyanine structure resulted in a highly stable, brilliant green pigment with superior chemical resistance. Since its commercial introduction, PG7 has supplanted traditional green pigments, such as Viridian, due to its greater durability and cost-effectiveness.

Phthalocyanine Green quickly gained popularity across multiple industries, especially in automotive coatings, artist paints, and high-performance industrial applications, following its commercial adoption in the late 1930s. The pigment's superior lightfastness and stability led to its widespread use in military-grade coatings during World War II, which further cemented its role in modern industrial applications. In the automotive sector, PG7 is used in metallic and pearlescent finishes that require long-lasting vibrancy. Its high tinting strength makes it a preferred fine art pigment for glazing techniques in oil and watercolor painting. Additionally, in industrial applications, PG7 is widely utilized in corrosion-resistant coatings for infrastructure and marine environments due to its chemical resilience.

Source

Phthalocyanine Green is a synthetic pigment produced by chlorinating copper phthalocyanine, which replaces hydrogen atoms in the phthalocyanine ring with 14 to 15 chlorine atoms. This chemical modification enhances the pigment’s stability, weather resistance, and lightfastness.

Phthalocyanine Green (PG7) is a synthetic pigment produced through a precise chlorination process of copper phthalocyanine blue. This process yields a mixture of isomers that, when finely controlled, result in the distinctive hue angle of approximately 175.9°. The hue angle, measured in degrees, represents the pigment’s position on the color wheel and indicates its relative color appearance. A hue angle of 175.9° places PG7 in the deep bluish-green range, making it more vibrant and cooler in tone compared to other green pigments. The pigment is manufactured under strict quality standards, exceeding industry norms to ensure superior color consistency, stability, and purity. Compared to standard-grade pigments, Phthalocyanine Green is produced with enhanced precision, resulting in a more refined particle size distribution and improved dispersion properties across various applications.

Permanence and Compatibility

One of the key attributes of Phthalocyanine Green (PG7) is its outstanding permanence. It demonstrates exceptional lightfastness—tested in various systems (including alkyd/melamine and 2C-acrylate)—with full shade reduction ratios ranging from 1:4.0 (1/3 SD) to 1:88.1 (1/25 SD). In this context, SD (Standard Deviation) refers to the measure of pigment dispersion and light-scattering properties in different concentrations, ensuring accurate performance assessments. Additionally, the pigment’s refractive index of 1.40 contributes to its strong transparency in glazes, making it particularly valuable for layering techniques in fine art painting. Its robust performance in both acidic and alkaline environments (as verified by DIN EN ISO standards) makes it ideally suited for demanding applications such as automotive, industrial, coil, and decorative coatings. The pigment’s resistance to heat and weathering ensures long-lasting color integrity in a wide range of media.

• Lightfastness: Rated 8 (highest) on the Blue Wool Scale, ensuring resistance to fading even under prolonged UV exposure.
• Chemical Resistance: Highly resistant to acids, alkalis, and organic solvents, making it ideal for outdoor applications.
• Weather Fastness: Phthalocyanine Green remains stable and vibrant in harsh environmental conditions, including high humidity and pollution.
• Photo-Degradation Behavior: Studies indicate that Phthalocyanine Green enhances the overall stability of alkyd-based artist paints under artificial solar radiation. Unlike other pigments, Phthalocyanine Green does not readily break down under UV exposure; instead, the alkyd binder undergoes degradation before the pigment, highlighting its suitability for long-term applications in fine arts and industrial coatings.
• Mixing and Compatibility:
  • It blends well with yellows to create a range of vibrant greens.
  • Mixes with blues to produce deep teal and turquoise hues.
  • Strong staining properties, requiring controlled usage in paint formulations.

Due to its high chroma and transparency, Phthalocyanine Green is extensively used in glazing techniques, layering applications, and ink formulations. Its transparency is an advantage in glazing and layering, allowing for luminous effects and depth, but can be a limitation in applications requiring high opacity, necessitating careful formulation in paints and coatings.

Oil Absorption and Grinding

Phthalocyanine Green is presented as a finely milled green powder with a density of 2.4 g/cm³. Its oil absorption value of 43 ml/100 g plays a crucial role in its performance, affecting the viscosity, drying time, and finish of various coatings. Higher oil absorption generally results in increased pigment-binder interaction, making it particularly suited for applications requiring rich pigmentation and stable dispersion in oil-based and acrylic mediums. However, ultra-fine particle pigments like Phthalocyanine Green can be difficult to disperse by hand mulling, especially in water-based mediums such as watercolor, tempera, and acrylic. The use of a wetting agent is recommended to facilitate better dispersion and achieve optimal results. Its bulk volume is 2.1 l/kg, with a specific surface area rated at 53 m²/g. These technical characteristics not only influence the pigment’s tinting strength but also dictate its behavior in dispersion and its compatibility with various binders. Such properties allow for efficient grinding and excellent incorporation into diverse coating systems, ensuring uniform color development and optimal coverage.

Grinding and Dispersion Properties:

• Fine Particle Size: Ensures smooth dispersion in various mediums.
• Shear-Sensitive: Requires precise milling to maintain optimal chromatic properties.
• High Tinting Strength: A small amount significantly influences color mixtures, making careful calibration necessary in paint formulations.

Toxicity

While Phthalocyanine Green (PG7) is not considered toxic, trace amounts of polychlorinated biphenyls (PCBs) can form as an unintended byproduct during the chlorination process used in its production. Regulatory agencies, such as the U.S. Environmental Protection Agency (EPA), have established strict thresholds for PCB content in commercial pigments, ensuring concentrations remain at safe levels well below hazardous limits. Advancements in manufacturing techniques continue to minimize PCB presence, maintaining compliance with global safety regulations and reinforcing the pigment’s suitability for a wide range of applications.

As a synthetic organic pigment, Phthalocyanine Green (PG7) is engineered to be compliant with industry-leading regulatory standards. Its certification under FDA 21 CFR § 178.3297 and ROHS directives ensures suitability for applications requiring stringent safety measures. Unlike alternative green pigments that may contain heavy metals or hazardous compounds, Phthalocyanine Green offers superior environmental and consumer safety without compromising performance. It complies with strict regulatory standards—including Germany’s BfR recommendations, USA (FDA) 21 CFR § 178.3297, and European directives (ROHS, EN 71-3, etc.)—ensuring it meets safety requirements for both industrial use and consumer products. Its inert nature minimizes any health risks during handling and application, making it a reliable choice for artists, manufacturers, and cosmetic formulators alike. It is compliant with international safety standards, including:

• FDA (21 CFR § 178.3297) – Approved for indirect food contact.
• EN 71-3:2013 (European Toy Safety Standard) – Safe for use in children's products.
• ROHS & CONEG Compliance – Free from hazardous heavy metals.

Avoid inhalation of fine pigment dust. Use protective equipment when handling dry powder in large quantities. Ensure proper ventilation in industrial spray applications.

Product Highlights

• Brilliant, Bluish-Green Hue: Offers intense chromatic purity and deep transparent undertones. Compared to historical green pigments like Malachite and Sap Green, PG7 exhibits superior stability and permanence. Malachite, a natural copper carbonate pigment, tends to fade and darken over time, while Sap Green, derived from plant-based sources, is known for its fugitive nature. Phthalocyanine Green, in contrast, maintains its vibrancy and lightfastness, making it a preferred choice for both fine arts and industrial applications. Compared to Phthalocyanine Green Yellow Shade (PG36), PG7 has a cooler, more bluish cast, making it ideal for vibrant turquoise mixes. Unlike Viridian, which has lower tinting strength and a more muted green tone, PG7 provides superior chromatic intensity and permanence.
• Exceptional Lightfastness & Weather Resistance: Remains vibrant under prolonged exposure.
• Highly Versatile: Ideal for oil, acrylic, watercolor, and industrial coatings.
• Non-Toxic & Environmentally Safe: Meets global safety regulations.
• High Tinting Strength: Requires minimal amounts for strong color effects.
• Excellent Chemical Resistance: Maintains stability in acids, alkalis, and solvents.

Phthalocyanine Green (PG7) continues to be a cornerstone pigment in the art and coatings industries, combining unmatched durability, color brilliance, and formulation versatility.

For a detailed explanation of the terms in the table above, please visit Composition and Permanence.

Note: SD refers to the Standard Depth, a metric used in pigment characterization to indicate color strength and tinting properties in standardized reductions with white pigment (typically Titanium Dioxide, TiO₂). For Phthalocyanine Green, the 1/3 SD reduction ratio of 1:4.0 and 1/25 SD ratio of 1:88.1 indicate that this pigment maintains its hue well even in high dilution, making it a highly stable and versatile red pigment across various applications, from industrial coatings to fine arts. For more information about Standard Depth, please visit Composition and Permanence.