synthetic adhesives based on saturated or unsaturated polyesters. The components of polyester adhesives include solvents (acetone or a mixture of acetone and alcohol), hardening initiators (organic peroxides or hydroperoxides) or hardening catalysts (tertiary amines or cobalt salts), and extenders (cement or silica). Other polymers, as well as monomers that are copolymerized with the unsaturated polyester, are added to increase the adhesiveness of the composition. The components of polyester adhesives are mixed immediately before use. Polyester adhesives without extenders are slightly colored or colorless liquid compositions with a working life ranging from several minutes to several hours.
Polyester adhesives are applied to the surfaces to be bonded with a brush or roller or by spraying. The boning conditions (temperature, pressure, and time) are governed by the composition of the adhesive and the nature of the materials to be joined. For example, certain adhesives made from polyester resins harden in several hours to 1–3 days at about 20°C or in several minutes to several hours at 60°-100°C. A small contact pressure –0.1–0.3 meganewtons per sq m, or 1–3 kilograms-force per sq cm—is usually applied during bonding. Polyester adhesives ensure high adhesion strength of plastics to plastics and other materials, and also of metal, rubber, wood, silica, and organic glass. The adhesive bonds are resistant to water, gasoline, and mold, as well as to weak acids and salt solutions; their working temperature range is from –60” to 80°C (sometimes up to 160°.). Polyester adhesives are widely used in the manufacture of optical products and furniture, and also in construction.
REFERENCESEntsiklopediia polimerov, vol. 3. Moscow, 1977.
See also references under ADHESIVES.
A. B. DAVYDOV