Methyltetrahydrophthalic Anhydride, MTHPA

Product Overview

Methyltetrahydrophthalic Anhydride (commonly abbreviated MTHPA) is a saturated (tetrahydro) phthalic anhydride derivative used as anhydride-type curing agent for epoxy resins. The methylated tetrahydrophthalic structure provides improved hydrolytic and thermal stability versus many aliphatic anhydrides while maintaining good reactivity and low discoloration — ideal for epoxy adhesives, coating systems, electrical encapsulants and composite matrices.
Methyltetrahydrophthalic Anhydride (MTHPA) is a colorless or light yellow liquid.

Typical Specifications

Melting Point	63-64 °C
Boiling Point	254.38°C (rough estimate)
Density	1.1708 (rough estimate)
Refractive Index	1.5500 (estimate)
Storage Temp.	-20°C Freezer
Solubility	DMSO (Slightly), Methanol (Slightly)
Form	Solid
Color	White

Key Applications & Advantages

Epoxy curing (primary): rapid room-temperature or elevated-temperature cure with good glass transition temperature (Tg) and chemical resistance — used in protective coatings, tooling resins and potting/encapsulation.
Composites & laminates: preferred for high-performance fiber-reinforced systems where thermal and chemical stability are required.
Adhesives & sealants: gives balanced cure speed and bond performance on metals and composites.
Electrical & electronics: low ionic impurities and good dielectric properties make MTHPA suitable for encapsulants and electrical potting.
Advantages: lower color development, good storage stability with appropriate inhibitors, and robust cured properties vs many aliphatic anhydrides.
It has been used in the curing agents for epoxy resins, solvent-free paints,laminated boards, epoxy adhesives, conductive adhesive and so on.
When used in the curing agent for epoxy resins, there are many excellent performances such as the long-term storage at room temperature, low freezing point, low volatility and low toxicity. Also widely used in motors, dry-type transformers, appliances capacitors, power capacitors, integrated circuits impregnation, casting and winding.

Formulation & Handling Notes

Stoichiometry: typically used with epoxy resins based on anhydride:epoxy equivalent ratios; accelerators (e.g., tertiary amines, imidazoles) are commonly used to tune pot life and cure profile.
Compatibility: miscible with common epoxy formulations and many solventborne or solventless coating systems.
Processing: recommended to keep containers sealed (anhydrides are moisture-sensitive); use standard PPE and avoid exposure to skin/eyes.

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