Лако-красочные материалы — производство

Many polymers exhibit some of the characteristics of the elastomeric family. Plastics, both thermoplastic and thermoset types, are very close both in terms of chemical structure and physical properties. Under a given set of conditions, plastics and elastomers will react much the same way. In fact, some polymer types are so versatile as to cross over into several different classes of compounds. The acrylic family is one, with rigid plastic com­pounds familiar to all in clear glass panel replacement applications, reactive two — component versions that provide a structural thermoset adhesive, rubbery polymers that can be used as sealants or adhesives, and soft thermoplastic polymers that can serve as a starting point for pressure sensitive adhesives or construction sealants, both solvent and water based. The polyurethane family is another, ranging from thermoplastic urethanes (TPUs) used in solid rubber and adhesive applications, to water — and solvent — based formulations, to hot-melt reactive systems for high performance applications where flexibility and green strength is a requirement, to rigid, glassy reactive thermoset polymer systems for structural applications. Other families of polymers that exhibit rubberlike properties include several cellulosic materials, a variety of thermoplastic resins such as acrylonitrile butadiene styrene (ABS) and poly(vinyl chloride) (PVC), and a whole host of vinyl acetate-based compounds. In addition, many silicone compounds and polysulfide systems also fall well into the elastomeric property category. And, obviously, natural rubber possesses these properties. But none of these materials will be described here since most will be covered in detail in other chapters of this treatise concentrating on these particular polymers.

Virtually all rubber materials, and plastic materials, can be made into an adhesive or sealant compound. This is because many elastomers begin as monomers dispersed in water or solvent and are polymerized in situ. Latex products can remain so, while solid elasto­mers that are extracted from either water or solvent systems can be solvated with an appropriate organic solvent system. In addition, most solid elastomers exhibit thermal flow characteristics which can make them suitable for hot-melt formulations. And since there are many different rubber polymer families, it stands to reason that there will be many different rubber-based adhesives to identify and describe. Some, however, have limited usage in the industrial and commercial world, and some have specialty applications because of inherent properties. But for the most part, only a few chemical types make up the majority of rubber-based adhesive and sealant applications. The major rubber families are: Polychloroprene, styrene-butadiene, butyl, and acrylonitrile butadiene. Another class is reclaim rubber, which exhibits many of the properties of the original polymer. The remainder of this chapter will concentrate on providing information on the history, chem­istry, forms of use, particular characteristics, and applications of these prime product types.