Other common forms of laminated plastics are composite sheet laminates that incorporate a third material bonded to one or both surfaces of the laminate. Metals most often used in composites are copper, aluminum, nickel, and steel. Nonmetallics include elastomers, vulcanized fiber, and cork. Vulcanized fiber is another product often classified with the laminated plastics because end uses are similar. The material is tough and has good resistance to abrasion, flame, and impact.
Phenolics are the most widely used resin in laminated plastics.
These low-cost resins have good mechanical and electrical properties and resistance to heat, flame, moisture, mild acids, and alkalies. Most paper and cloth-reinforced laminates are made with phenolics. Polyesters are used for both electrical and mechanical service requiring moderate heat resistance. The resins are usually mineral filled to improve dimensional stability and flame retardancy and to reduce cost. Malemine resins are used primarily in electrical-grade laminates because of their excellent resistance to arcing and tracking, high mechanical strength, and good resistance to alkalies.