DGEBA

What it is

DGEBA is bisphenol A capped at both ends with a glycidyl ether (epoxide) group (molecular weight 340.4 g/mol). The pure monomer has an epoxide equivalent weight (EEW) of 170 and is a crystalline solid that melts at about 40–44 °C. Commercial “standard” liquid epoxy resins are mostly DGEBA plus a small fraction of higher oligomers, giving an EEW of roughly 182–192 and a viscosity in the order of 10,000–14,000 mPa·s at 25 °C.

Role in coatings

DGEBA-based liquid resins are the main binder in two-component epoxy coatings: floor systems, tank and pipe linings, primers, marine and protective coatings, and adhesives and composites. They are cured with amines, polyamides, anhydrides or phenalkamines, and are often blended with reactive diluents or bisphenol F resins to lower viscosity and resist crystallization.

Chemistry & key properties

DGEBA is made by reacting bisphenol A with epichlorohydrin under alkaline conditions. Each epoxide ring opens when it reacts with an amine N–H, forming a hydroxyl group and a new C–N bond; with two epoxides per molecule, curing builds a 3D network.

• EEW and n-value: as oligomer content (n) rises, EEW and viscosity increase until the resin becomes a solid.
• Crystallization: high-purity resins can crystallize in cold storage, turning cloudy or grainy.
• Performance: the aromatic backbone gives adhesion, chemical resistance and strength, but chalks under UV.

Handling & storage

Liquid epoxy resins cause skin and eye irritation and are well-known skin sensitizers; repeated unprotected skin contact is the most common cause of epoxy dermatitis. Wear nitrile or other suitable gloves and eye protection, and avoid skin contact with uncured material. They are toxic to aquatic life, so dispose of waste correctly. Store at moderate temperature; crystallized resin can be restored by warming to around 50–60 °C and stirring until clear.