carbamide plastics, plastics based on thermosetting synthetic resins obtained from the reaction of urea, melamine, and other amino compounds with aldehydes (usually formaldehyde). The most common amino plastics are those based on urea-formaldehyde and malamine-formaldehyde resins. Amino plastics are light-resistant, odorless, can be painted any color (even light tones), and are physiologically harmless. They are resistant to weak acids and alkalis, alcohol, benzine, acetone, chloroform, and other organic compounds. Melamine-formaldehyde resins are used to manufacture articles more resistant to heat and moisture than those made from urea-formaldehyde resins.
Amino plastics are produced in industry in the form of molding powder, laminated plastics, or porous materials. Sulfite pulp, wood flour, asbestos, talc, and other materials are used as fillers for molding powder. The density of molded articles made from amino plastics based on urea-formaldehyde resins (using sulfite pulp as the filler) is 1,400 kg per cu m, the tensile strength is 35–50 meganewtons per sq m (600–900 kilogram forces per sq cm), the thermostability (after Martens) is 100–120°C, water absorption is 1–1.5 percent, and dielectric permeability (at 50 hertz) is 5–7. Molding powder is used to manufacture consumer goods (haberdashery and office supplies, household articles, children’s toys, and other articles), parts for electrical lighting equipment (shades, buttons, plugs, switches, and so on), and cases for telephones, radios, television sets, and other instruments. Sheets of paper and fabric (cotton, asbestos, or glass) are used as fillers in the manufacture of laminated plastic. Such plastic has a density of 1,400 kg per cu m, a tensile strength of 100 meganewtons per sq m, (1,000 kilogram forces per sq cm), and water absorption of about 4 percent. Laminated plastics made from amino plastic are suitable for decorative purposes—table facings, walls, kiosks, ships’ bulkheads, and so on. They can be washed with warm water and soap.
REFERENCEPetrov, G. S., and A. N. Levin. Termoreaktivnye smoly i plasticheskie massy. Moscow, 1959.
Spravochnik po plasticheskim massam, part 1. Moscow, 1967. Page 396.