Use
Phenol-formaldehyde resin is a synthetic resin, commonly known as phenolic, made by the reaction of phenol and formaldehyde, and employed as a molding material for the making of mechanical and electrical parts. The resins are also used for laminating, coatings, and casting resins.
Phenolic resins are used most extensively as thermosetting plastic materials, as there are only a few uses as thermoplastics. The polymer is composed of carbon, hydrogen, oxygen, and sometimes nitrogen. Its molecular weight varies from a very low value during its early state of formation to almost infinity in its final state of cure. The chemical configuration, in the thermoset state, is usually represented by a threedimensional network in which the phenolic nuclei are linked by methylene groups. The completely cross-linked network requires three methylene groups to two phenolic groups. A lesser degree of cross-linking is attainable either by varying the proportions of the ingredients or by blocking some of the reactive positions of the phenolic nucleus by other groups, such as methyl, butyl, etc. Reactivity can be enhanced by increasing the hydroxyl groups on the phenolic nuclei, for example, by the use of resorcinol.
The outstanding characteristics of phenolics are good electrical properties, very rigid set, good tensile strength, excellent heat resistance, good rigidity at elevated temperature, good aging properties; also, good resistance to water, organic solvents, weak bases, and weak acids. All these characteristics are coupled with relatively low cost.