Ask The Expert: Coating Textile Braids

Q. I am a manufacturing engineer for a company that manufactures various types of hose products. We use textile braid as a reinforcing layer in rubber hose. In our manufacturing process we apply adhesive coatings over certain textile braid for reinforced hose constructions. On other hose items, we apply a lacquer coating over the textile braid. In order to dry out the lacquer coatings, the hose travels vertically through a 50-ft-high tower, passing through a series of electric heating elements. The liquids are applied by spraying. Naturally, this results in a lot of wasted overspray. This is a somewhat antiquated method of coating hose. We would like to investigate the possibility of a more updated arrangement such as electrostatic spraying. We thought you would be aware of some of the newer technologies in other industries which could prove to be of assistance or benefit to us in changing our method of coating hose braid. What do you suggest? L.C.

A. Electrostatic spraying will increase transfer efficiency by reducing overspray. Liquid coatings, which are applied by electrostatic spraying to metallic substrates, can also be applied to non-metallic substrates if they can be made to be electrically conductive. Special surface treatments are applied to wood and plastics to make them conductive. Heating will often produce the same effect also. Since textiles are usually surface treated at the mill during manufacture, a conductive coating can be applied to the filaments before the braid is woven.

Another approach would be using a UV curable, heat-reactive adhesive to coat the braid. UV curable coatings are 100 percent reactive (no solvents) and can be cured instantaneously in a relatively short UV light tunnel, thereby eliminating the need for a long, heated drying tower.