Лако-красочные материалы — производство

The cure speed and adhesion of an anaerobic sealant can be increased by treatment of the surface with a solution containing activating chemicals. Early anaerobic thread lockers were strongly affected by part cleanliness, and degreasing the parts with a chlorinated solvent improved performance dramatically. The condensation product of an aldehyde and a primary or secondary amine, a sulfur-containing free-radical accelerator (LVI), or a compound of an oxidizable transition metal were some of the materials that could be added to activate the anaerobic cure [69-71]. Ferrocene (LVII), a derivative containing the ferrocene moiety, or a polymer incorporating ferrocene was an effective activator for anaerobic adhesives [72]. The copper, cobalt, manganese, or chromium salts of an acid phosphate acrylic monomer (LVIII) were found to be effective activators as well as adhe­sion promoters [73].

II. APPLICATIONS

1. Thread locking. The first applications for anaerobic adhesives were for locking threaded fasteners. Filling the ‘‘inner space’’ between a nut and bolt with a hard, dense material prevents self-loosening.

2. Thread sealing. The effect of filling the space between threaded parts or the space between inner and outer pipe threads provides a seal that can prevent the leakage of oil and other fluids in machinery as well as prevent corrosion of the threaded parts.

3. Retaining. Cylindrical press-fits and bearing assemblies can be retained with anaerobic adhesives, allowing accurate alignment and relaxed tolerances. Retaining and sealing of cup plugs and oil seals in castings is a major application.

4. Impregnation. Powdered metal parts, porous castings, and welds can be sealed against leakage of liquids or gases. This impregnation can also allow such parts to be plated and improves their machinability.

5. Preapplied. Thread lockers and sealants are made that can be coated on threaded parts in the form of a dry-to-the-touch film. These preapplied materials remain inert until assembly releases a quick-curing resin.

6. Gasketing. Anaerobic flange sealants can be applied manually or by automated methods such as tracing, stenciling, and screen printing. These products can eliminate a variety of preformed, precut gaskets and can also be used as a gasket dressing.

7. Structural bonding. Tough structural bonds can be achieved with some anaerobic adhesives for bonding components such as ferrite magnets, honing stones, identification tags, and decorative inserts.

Other applications include the fabrication of foundry molds [74,75] and the surface mounting of electronic components [76].