Phenolic Novolac Resin Powder (Hexamine-Hardened)

Phenolic Novolac Resin Powder is a thermoplastic (uncured) phenol-formaldehyde resin produced under acid-catalyzed conditions with excess phenol relative to formaldehyde (F/P molar ratio 0.75-0.85), resulting in a linear oligomeric structure without methylol groups. The resin is solid at room temperature (softening point 80-110°C, Durran method) and requires a separate hardener — hexamethylenetetramine (hexamine, HMTA) at 10-15 phr — to crosslink and cure at 150-180°C via methylene bridge formation.

Phenolic novolac powder is the primary molding compound resin for phenolic compression molding, transfer molding, and injection molding of thermoset parts. Blended with mineral or glass fiber reinforcement, the compound produces rigid, dimensionally stable parts with excellent heat resistance (HDT >200°C under 1.82 MPa), dimensional stability under thermal and mechanical loading, and inherent flame retardancy (UL94 V-0 at 1.6mm).

Applications include phenolic molding compounds for electrical components (switches, circuit breakers, connectors), automotive brake pads (friction compounds), phenolic refractory binder for industrial furnace applications, baked carbon and graphite electrode binder, and abrasive grain bonding for grinding wheels (vitrified and resin-bonded). Novolac resins offer 12-24 month shelf life at ambient temperature versus the limited shelf life of resole resins under refrigerated storage.