Name: Pigment Blue 15:1 (Alpha Copper Phthalocyanine)
Brand: Coatingsink
SKU: pigment-blue-15-1-alpha
Availability: InStock

Question 1

What is the difference between Pigment Blue 15:1 (alpha) and 15:3 (beta)?

Accepted Answer

PB 15:1 and 15:3 are two crystal polymorphs of copper phthalocyanine blue. The alpha form (15:1) has a reddish-blue hue and slightly higher tinting strength, but it is metastable and can undergo crystal phase transformation (flocculation/recrystallization) in aggressive solvent systems. It is stabilised with chlorination to improve solvent fastness. PB 15:3 (beta form) is the more stable polymorph with a cleaner, greener blue hue and is preferred for waterborne systems, while 15:1 is favoured in solvent-based gravure inks for its reddish tonal depth.

Question 2

How do I prevent crystal phase change when using PB 15:1 in solvent inks?

Accepted Answer

Phase transformation in PB 15:1 is triggered by high-solvency aromatic and ketone solvents, especially at elevated temperatures during milling. To minimise the risk, choose a stabilised (chlorinated) grade specifically marketed for solvent systems, use mild solvents where possible, limit milling temperature below 50°C, and incorporate a small amount (1–2%) of rosin-based or polymeric dispersant that adsorbs on crystal surfaces. Pre-dispersed flush pastes in the target solvent system further reduce transformation risk.

Bulk Density	80–180 g/l
Crystal Form	alpha (reddish blue)
Lightfastness	8
Heat Stability	300°C
Tinting Strength	100–115% (vs 15:3)

Pigment Blue 15:1 (Alpha Copper Phthalocyanine)

Specifications

FAQ

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