HX AP-14 Strontium aluminum polyphosphate hydrate

What Is HX AP-14 Strontium Aluminum Polyphosphate Hydrate

HX AP-14 is a premium white anti-corrosion pigment based on strontium aluminum polyphosphate hydrate chemistry. The incorporation of strontium ions enhances the passivation layer density on ferrous and aluminum substrates, delivering superior long-term corrosion inhibition compared to conventional zinc or calcium-based phosphates. With a slightly acidic pH range (4.5-7.0), AP-14 is particularly effective in solvent-based industrial coatings where controlled acidity promotes better substrate wetting and adhesion. Its higher oil absorption (27-49 g/100g) and increased water-soluble content (<5.0%) reflect a deliberately engineered solubility profile — releasing active inhibitive species gradually over the coating lifetime rather than exhausting rapidly.

Key Features

• Strontium-Enhanced Chemistry — Strontium ions produce a denser, more durable passivation film than calcium or zinc alternatives, improving long-term corrosion resistance
• Controlled Solubility Profile — Water-soluble matter <5.0% ensures gradual, sustained release of inhibitive ions throughout the coating service life
• Acidic pH Compatibility (4.5-7.0) — Naturally compatible with acid-catalyzed coating systems and solvent-based alkyds without pH adjustment
• Excellent Substrate Wetting — Slightly acidic character improves adhesion on ferrous substrates, reducing the need for additional wetting agents
• Solid Industrial Performance — Optimized for industrial paints, decorative solvent-based systems, and waterborne coatings
• Stable Hydrate Structure — The polyphosphate hydrate form maintains corrosion inhibition activity even after extended storage

Recommended Applications

✅ Recommended  |  ⚪ Suitable  |  ❌ Not Recommended

Technical Data

Packaging

25 kg/bag. Custom packaging available upon request.

Frequently Asked Questions

What advantage does strontium provide over zinc or calcium in anti-corrosion pigments?

Strontium ions have a larger ionic radius than calcium (1.18 Å vs. 1.00 Å), which produces a denser, more tightly packed passivation film on metal substrates. This results in better barrier properties and longer corrosion protection, particularly in aggressive environments such as coastal or industrial atmospheres. Additionally, strontium-based pigments avoid the environmental concerns associated with zinc leaching while outperforming calcium-based alternatives in long-term salt spray testing.

Why does AP-14 have higher oil absorption (27-49) than other grades?

The higher oil absorption is a direct consequence of the strontium aluminum polyphosphate hydrate structure — the hydrate component creates additional surface area and porosity at the microscopic level. While this means slightly higher binder demand, it also means the pigment can carry more active inhibitive species per unit weight. In practice, formulators typically use AP-14 at a lower PVC than AP-11 or AP-13, achieving equivalent or better corrosion protection at a lower loading level.

Is the acidic pH (4.5-7.0) a concern for waterborne systems?

Not for most waterborne acrylic and epoxy systems, which are designed with sufficient buffering capacity. The mildly acidic character can actually improve substrate wetting on ferrous metals — similar to how a light phosphoric acid wash improves adhesion. However, for highly pH-sensitive systems or formulations containing acid-reactive pigments (such as certain grades of aluminum flake), we recommend AP-12 (pH 8.5-11.5) as an alkaline alternative, or running a small-scale compatibility test before full production.

Disclaimer — This Technical Data Sheet reflects our best understanding of typical product properties at the time of publication. Listed values are representative of standard production and are not intended as specifications, contractual parameters, or fitness guarantees. Batch variations within normal manufacturing tolerances may occur; users should verify critical parameters against their own requirements before use. Processing methods, formulations, and end-use environments are beyond the manufacturers control. The buyer assumes full responsibility for confirming product suitability through its own testing and quality assurance. No intellectual property license is granted or implied. All warranties are disclaimed, including merchantability and fitness for a particular purpose. The manufacturer is not liable for incidental, consequential, or special damages. All sales are governed by the manufacturers standard terms, available upon request. This product may contain particles below 0.1 μm.