synthetic adhesives made from derivatives (mainly esters) of acrylic, methacrylic, and cyanoacrylic acids. The most common acrylic adhesives are made from monomeric esters and from solutions of polyacrylates in the monomers themselves, in inert organic solvents, or in mixtures of the monomers and solvents; some acrylic adhesives are used in the form of aqueous emulsions.
Modifiers added to acrylic adhesives to control the viscosity of the adhesives and the elasticity of the hardened compositions and to improve the strength of bonding and the resistance to high temperatures include vinyl acetate, styrene, butadiene, and other monomers; phenol-formaldehyde, urea-formaldehyde, and epoxy resins; cellulose esters; rubbers; and fillers and plasticizers.
Unmodified solutions of acrylic adhesives are transparent, colorless, or slightly colored mobile or syrupy liquids. Emulsions of acrylic adhesives are opaque white or light-yellow liquids. The consistency, transparency, and color of modified acrylic adhesives depend on the type and quantity of additives.
The components of acrylic adhesives are most frequently mixed immediately before use. Some acrylic adhesives, which are stable during storage (for example, aqueous emulsions or solutions in inert solvents), are supplied in ready-to-use form. Acrylic adhesives are applied to the surfaces to be bonded using a brush or roller or by spraying. The adhesive composition hardens as a result of evaporation of the solvent or polymerization of the monomers initiated by organic peroxides or the salts of alkali metals. Cyanoacrylic adhesive compositions harden rapidly under the action of atmospheric moisture.
Modified acrylic adhesives, which form adhesive compositions resistant to oil, gasoline, and mold and can withstand temperatures from—60° to 60°C (sometimes up to 100°-120°C), are used to bond metals and plastics to one another, as well as to rubber and ceramics. Unmodified acrylic adhesives are used to bond plastics to one another or to metals, wood, paper, silicate glass, and organic glass, including glass parts for optical instruments. These adhesives are used in the production of non woven materials and paper packaging materials, for attaching labels, and in printing. Acrylic adhesives containing polyisobutylene are used to make sticky films and patches. Cyanoacrylic adhesives are used to bond body tissues during surgery.
REFERENCEEntsiklopediia polimerov, vol. 2. Moscow, 1974.
See also references under ADHESIVES.
A. B. DAVVDOV