Лако-красочные материалы — производство

The designations of adhesives are often derived from their base polymers, such as ‘neoprene contact adhesives’, ‘phenolic resin adhesives’ or ‘epoxy resin adhesives’. In this chapter, we will apply this classification principle to all chemically setting systems. Adhesives are rarely made from only one base polymer; more often, they are formulations of several organic or inorganic components because they must combine seemingly mutually exclusive properties to yield a material capable of delivering required functions. Adhesives must not be too viscous, in order to allow pumping, mixing and wetting of the adherent. In the noncured state they must not leak from the bond-line and so must be ‘thixotropied’. In the cured state, they must not be too brittle; they must present a plastic deformability with minimum creep under repeated load. Only a combination of components in specific formulations allows specific properties to be conferred to an adhesive; this is the art of adhesive manufacturers who skillfully combine the components to meet the customers’ specifications. The base resins confer the essential basic properties to an adhesive, while other characteristics result from a fine-tuned formulation. Criticism is sometimes leveled that adhesives contain too many components, and this is not completely unfounded. Adhesive manufacturers often receive short-term specifi­cations to deliver test products with insufficient time or money to create new formulations. Hence, they select a ready formulated product and fine-tune it to new requirements by adding further components; moreover, the consumer need not know the constitution of the adhesive as long as it functions well. However, this principle cannot be applied to high-performance bonding, where the recommen­dation is to make a confidentiality agreement with the manufacturer, who must make available the formulation details so that users can perform analytical screen­ings for quality assurance purposes. Although, occasionally, adhesive manufac­turers will not accept this procedure, it has long been widely adopted and proven for various other materials, and has contributed to building confidence in new technologies.

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