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.

Unlike natural mineral-based pigments, Phthalocyanine Green is manufactured under controlled conditions, ensuring batch-to-batch consistency in hue, particle size, and performance. While synthetic pigments offer superior durability and color uniformity, they can lack the subtle variations and depth found in some natural alternatives, which may be preferred in certain artistic applications. It is insoluble in water and most solvents, making it an ideal choice for oil-based and water-based applications.

Permanence and Compatibility

• 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 has a moderate oil absorption rate, requiring approximately 43 ml of linseed oil per 100g of pigment for paint production. This is comparable to other synthetic organic pigments, such as Phthalocyanine Blue (PB15), which has a similar absorption range but is significantly lower than traditional earth pigments like Raw Umber, which can absorb up to 60 ml per 100g.

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

Phthalocyanine Green is classified as non-toxic and environmentally safe. However, concerns have been raised regarding the environmental impact of its production, particularly the use of chlorinated precursors, which require stringent waste management protocols. Advances in sustainable manufacturing are addressing these challenges to minimize the ecological footprint. 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.