The amino resins are formed by an addition reaction of formaldehyde and compounds containing NH 2 amino groups. They are supplied as liquid or dry resins and filled molding compounds. Applying heat in the presence of a catalyst converts the materials into strong, hard products. The base resin used in urea and melamine molding compounds is water-white and transparent. Translucent and opaque colors are produced by adding pigments and opacifying agents.
Cellulose fibers improve strength and dimensional stability and reduce light transmission.
Moldings made from amino compounds are hard, rigid, abrasion resistant, and have high resistance to deformation under load. They do not impart taste or odor to foods, and they have excellent electrical insulation characteristics. Urea and some melamine molding compounds have flammability ratings of 94V-0. Melamines containing alpha cellulose, mineral, or glass fibers have the greatest flame resistance. These materials can be used for appliance parts classified by UL as indirect supports of current-carrying parts.