Лако-красочные материалы — производство

Before setting, reactive adhesives consist predominantly of reactive low molecular mass monomers and/or oligomers that, during curing, are converted by chemical reactions into high molecular mass, often three-dimensionally cross-linked polymers. Reactive adhesives can be divided into polymerization, polyaddition, and polyconden­sation adhesives. Vulcanizing reactive adhesives are a special group.

Reactive adhesives are marketed as one-pack, two-pack, and no-mix formulations. Two-pack adhesives must be completely mixed in the correct ratio before use. The mixtures have a limited pot life. One-pack adhesives are easier to handle during application. They are hardened by heat, by the catalytic action of the substrate, or by atmospheric moisture.

Cold-setting reactive adhesives harden within a few hours to several days at room temperature or slightly elevated temperature. An exception are cyanoacrylate adhesives, which cure on several substrates within seconds or minutes, as do UV/EB curable adhesives. Warm-setting adhesives generally require temperatures in the range 80-100 °С, and hot-setting adhesives 100-250 °С. Adhesive joints of particularly high quality are obtained mainly with warm — and hot-setting systems. In many cases, warm setting leads to higher bond strengths, even in the case of systems that normally harden
at room temperature. However, even certain cold-setting adhesives produce outstanding bond strengths under favorable bonding conditions.

To avoid mixing errors in the case of two-pack adhesives, no-mix adhesives are available. In this case, one of the surfaces to be bonded is pretreated with the adhesive resin, the other with the adhesive primer, and the bond is formed instantly when the two surfaces are brought together.