Лако-красочные материалы — производство

Naim Akmal[14]

University of Cincinnati, Cincinnati, Ohio, U. S.A.

A. M. Usmani

Firestone, Carmel, Indiana, U. S.A.

I. INTRODUCTION

High-sulfur-containing polymers known as polysulfides were introduced by Thiokol in 1928. The solid polysulfide polymers contain 37 to 82% bound sulfur, but the more important liquid polymers containing about 37% sulfur find application in high- performance sealants and adhesives. These conventional polysulfide polymers are now available from Morton International (United States), Toray Thiokol (Japan), and Chemiewerke (Germany). During the 1960s and 1970s, new mercaptan-terminated polymers were introduced that have varying polymer backbones. The properties, especially the chemical resistance of the polymers, depend on their backbone structures.

Polysulfide sealants account for about 43 million pounds of the total 500 million pounds of the U. S. sealant market. Major fields of polysulfide sealants are aircraft, automotive, con­struction, and marine. End uses of polysulfides are very diversified: for example, sealing integral fuel tanks, sealing pressurized cabins, potting electrical connectors, sealing bolted steel tanks, glazing of windshields, glazing of rear automotive lights, recreational vehicles, vibration damping in trailers, gas tank liners, curtain walls, building exteriorjoints, highway joints, airfields, insulated glass, swimming pools, flight decks, decks of pleasure craft, solid — rocket fuel binder, relief maps, printing rolls, dental impressions, hoses, and gaskets.

In this chapter we describe the chemistry and technology of polysulfide polymers; processing and manufacture of polysulfide sealants and adhesives, including their formula­tions; curing reactions; and characterization and testing. Adhesion considerations are also discussed briefly.