Phenalkamine Hardener (Cashew-Based)

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Key Features

  • Cures at 0°C and even under water due to hydrophobic phenolic backbone
  • Excellent adhesion to steel in salt spray and water immersion
  • Good moisture displacement from damp or wet substrates
  • Partial bio-based content from cashew cardanol
  • Outstanding performance in marine and offshore environments

Phenalkamine Hardener (Cashew-Based) is derived from the Mannich reaction of cardanol (a natural phenol extracted from cashew nut shell liquid) with formaldehyde and a polyamine. This unique chemistry produces a hardener that combines the moisture tolerance and low-temperature cure capability of aliphatic amines with the chemical resistance and substrate adhesion characteristics approaching those of aromatic or cycloaliphatic amines. Phenalkamines are the benchmark hardener for demanding marine, offshore, and underwater epoxy coating applications, particularly for wet and submerged surface coating where conventional amines fail. They cure down to 0°C and even under water due to the hydrophobic phenolic backbone, which displaces moisture from the substrate surface. Cured films exhibit excellent adhesion to steel, aluminum, and concrete in salt spray, water immersion, and cathodic disbondment tests. Tg is moderate (60–90°C), chemical resistance is good (fuels, oils, mild acids). The bio-based content (cashew cardanol) provides partial renewable origin. Mix ratios vary by grade; typical range is 100:40–60 (epoxy:hardener by weight).

Specifications

ParameterValue
TypeCardanol-based Mannich-modified amine
AppearanceDark amber to brownish liquid
Shelf Life12 months in sealed container
Amine Value200–350 mg KOH/g
Viscosity (25°C)500–3,000 mPa·s
Minimum Cure Temperature0°C (sub-zero with special grades)

Applications

Underwater and splash-zone epoxy coating for marine structuresWet surface and damp substrate epoxy primersOffshore platform coating in hostile salt environmentsBallast tank and bilge epoxy coatings (NORSOK M-501 type)Potable water pipe and reservoir lining (food-contact grades)

FAQ

The hydrophobic long alkyl chain of cardanol (from cashew nut shell liquid) makes phenalkamine molecules surface-active — they preferentially wet and displace water molecules from steel and concrete substrates. This surface activity, combined with good reactivity at low temperatures, allows curing in wet and submerged conditions where conventional amines would be pushed off the substrate by water.

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