What Does Epoxy Phenolic Resin Mean?
Epoxy phenolic resins are phenolic resins modified at the phenolic hydroxyl group to include an epoxide functional group (usually a –CH2-(C2H3O) group, where -(C2H3O) is the three-membered epoxide ring). The added functionality of the phenolic resin increases the ability for the resin to crosslink, creating a stronger polymer with high resistivities. A common type of epoxy phenolic resin is epoxy phenol novolac, in which the phenolic resin is a phenolic novolac resin, consisting of short polymers between 10-20 repeating units.
These resins are often used as coatings or resistive top coats for drums, pipes, floors, tanks and automotive parts. The high chemical and solvent resistivities and temperature compatibility of epoxy phenolic resins are most useful in high-performance applications and corrosion resistance.
Corrosionpedia Explains Epoxy Phenolic Resin
Phenolic resins by themselves produce a high degree of crosslinking through thermosetting, creating high resistive properties to chemicals and water. These phenolic resins still have non-utilized hydroxyl groups (-OH) within the portion of the polymer repeating unit derived from phenol (C6H5OH). Epoxy phenolic resins modify this position with an organic group that contains an epoxy functional group, such as epichlorohydrin (Cl-CH2-(C2H3O)). The phenol hydroxide group replaces the chloride to produce an ether linkage between the phenol and the epoxide (C6H5-O-CH2-(C2CH3O)). When thermoset, the modified polymer has more location in which it can crosslink and that added functionality increases the crosslinking network of the produced plastic coating.
The type of phenolic resin and epoxide component used alters the properties of the epoxy phenolic resin, leading to a wide range of physical properties depending on the formulation. Each formula may have a particular advantage, such as ease of application, higher resistivitity to chemical attack, corrosion or temperature. The choice of formulation depends on the particular application. Epoxy phenolic resins are typically colored and so top coats are sometimes used on top for aesthetic purposes.