Name: Methylhexahydrophthalic Anhydride MHHPA Curing Agent
Brand: Coatingsink
SKU: epoxy-curing-agent-anhydride-mhhpa
Availability: InStock

Question 1

What accelerator is required with MHHPA and at what loading?

Accepted Answer

MHHPA requires a tertiary amine or imidazole accelerator to initiate anhydride ring-opening. 1-methylimidazole (1-MI) at 0.5–1.0 phr or benzyldimethylamine (BDMA) at 0.5–1.5 phr are standard choices. Accelerator level controls pot life and exotherm; higher loadings shorten gel time but increase peak exotherm in large pour masses, which can cause cracking in thick castings.

Question 2

What is the correct stoichiometric ratio of MHHPA to standard liquid BPA epoxy resin?

Accepted Answer

For a standard liquid bisphenol-A epoxy with EEW ~185 g/eq, the theoretical anhydride-to-epoxide equivalent ratio is 0.85:1. Formulators typically use 0.80–0.90 equivalents of anhydride per epoxide; sub-stoichiometric dosing minimizes ionic impurities and lowers dielectric loss in electrical potting applications while still achieving maximum Tg.

Question 3

What cure schedule is recommended for electrical potting and encapsulation?

Accepted Answer

A two-stage cure is standard: gel at 80–100°C for 1–2 hours, then post-cure at 140–160°C for 2–4 hours to reach full conversion. Post-cure is critical for maximum Tg (typically 120–140°C) and optimal dielectric strength. Omitting post-cure leaves residual anhydride that hydrolyzes in humid service environments, degrading electrical insulation performance.

Purity	≥98.5%
Acid Value	660–680 mg KOH/g
Color (APHA)	≤30
Density (25°C)	1.15 g/ml
Viscosity (25°C)	55–65 mPa·s

Methylhexahydrophthalic Anhydride MHHPA Curing Agent

Specifications

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