Phthalocyanine Blue (Copper Phthalocyanine, C.I. Pigment Blue 15) Storage & Tank Compatibility

Storing Phthalocyanine Blue (Copper Phthalocyanine, C.I. Pigment Blue 15)? Start Here

Phthalocyanine Blue, also known as copper phthalocyanine or C.I. Pigment Blue 15, is a brilliant, lightfast blue organic pigment with the formula C₃₂H₁₆CuN₈ (CAS 147-14-8). A dark blue crystalline powder, it is built around a copper-centered macrocyclic ring that gives it outstanding tinting strength along with near-total resistance to acids, alkalis, heat, light, and common solvents. It is practically insoluble in water (less than 0.1 g/100 mL) and in most organic media, so it is shipped and stored either as a dry powder or, far more commonly in bulk handling, as a stabilized water- or glycol-based dispersion. Those aqueous and glycol carriers are mild and fully compatible with polyethylene, which is why pigment slurries are routinely stored in HDPE and XLPE tanks. The pigment itself poses essentially no chemical-attack risk to plastic, metal, or elastomer storage materials.

Is Phthalocyanine Blue Safe to Store in Polyethylene (HDPE / XLPE) Tanks?

Yes. Phthalocyanine Blue is one of the most chemically inert colorants in industrial use, and in the carriers in which it is actually handled - dry powder, water-based dispersions, and glycol-based dispersions - it is fully compatible with both HDPE and crosslinked polyethylene (XLPE). Polyethylene is, in practice, the default vessel for pigment slurries and tinted aqueous concentrates. The pigment will not soften, swell, stress-crack, or chemically degrade polyethylene, and PE will not contaminate or shade-shift the pigment.

The one caution is the dispersing medium, not the colorant. Phthalocyanine Blue is manufactured and sometimes reworked via an acid-paste route in concentrated sulfuric acid. Concentrated sulfuric acid is a strong oxidizer that attacks and embrittles polyethylene, so any acid-process stream must be kept in acid-rated, lined equipment - never in a standard PE tank. For ordinary tinting, dosing, and storage of the finished pigment or its water/glycol dispersion, HDPE and XLPE are excellent, long-service choices.

Material compatibility at a glance

Phthalocyanine Blue is an exceptionally inert, water-insoluble organic pigment, so storage compatibility is governed almost entirely by the carrier, not the colorant. As a dry powder or as the usual water- or glycol-based dispersion, it is fully compatible with HDPE and XLPE (S), as well as PP, PVC/CPVC, 316 stainless steel, EPDM, and FKM. Polyethylene tanks are in fact the industry-standard vessel for pigment slurries and tinted aqueous concentrates. The only incompatibility comes from the dispersing medium: the pigment is processed or purified in concentrated sulfuric acid, and that acid - not the pigment - is unsuitable in PE and demands acid-rated, lined equipment.

Ratings: S suitable · C conditional / limited · U unsuitable. Verify against the cited resistance charts and your concentration/temperature before specifying.

The safety that actually matters

• Wear safety glasses or goggles; the dust can cause serious eye irritation (H319). Use gloves and avoid prolonged skin contact (H315).
• Control dust - use local exhaust or a respirator when handling dry powder, as airborne particulate may irritate the respiratory tract (H335) and fine organic dust can form combustible dust clouds.
• Avoid ingestion; the material is harmful if swallowed (H302). Practice good hygiene and do not eat or drink in handling areas.
• Keep the dry powder away from open flame and high heat; although the pigment itself is not readily flammable, it is handled as a combustible solid and decomposes near 600 C, releasing copper, nitrogen, and carbon oxides.
• Never store acid-paste (concentrated sulfuric acid) pigment streams in polyethylene; use acid-rated lined vessels and segregate from strong oxidizers.
• Contain spills and avoid release to waterways; the pigment is persistent and non-biodegradable in the environment.

Common questions

Can I store Phthalocyanine Blue dispersion in an HDPE or XLPE tank?

Yes. Both the dry pigment and its water- or glycol-based dispersions are chemically inert toward polyethylene, and HDPE/XLPE tanks are the industry-standard vessels for pigment slurries and tinted aqueous concentrates. The pigment will not swell, soften, or stress-crack the tank.

Is Phthalocyanine Blue soluble in water?

No. It is practically insoluble in water (less than 0.1 g/100 mL at 20 C) and in most organic solvents. It is handled as a dry powder or as a stabilized dispersion. It dissolves only in concentrated sulfuric acid, which is itself unsuitable for PE storage.

Is Phthalocyanine Blue corrosive or reactive?

No. The pigment is exceptionally stable and non-corrosive, with an NFPA reactivity rating of 0 and resistance to acids, alkalis, heat, and light. Compatibility concerns come from the carrier medium (for example, an acid-paste sulfuric-acid stream), not from the pigment itself.

What hazards should I plan for when handling the dry powder?

Primarily dust control. The powder can irritate eyes, skin, and the respiratory tract and is harmful if swallowed, so use eye protection, gloves, and dust controls. As a fine organic solid it should also be kept away from ignition sources to avoid combustible-dust conditions.