HOT MELT ADHESIVE FOAM BONDING PROCESS AND APPARATUS

摘要

The solid adhesive is placed in a tank (15) in which it melts to form a reserve of melt. The latter descends the walls (34, 35) of the tank towards the inlet (20) of a pump (16). A gas is transmitted at a pressure slightly above atmospheric pressure by a conduit (21) towards the air inlet. The liquid and the gas which enter simultaneously are mixed in the pump (16) and expelled under pressure into a conduit (22). The solution formed then passes through a filter (18), conduits (23) and a pipe (25) towards a dispenser gun at the outlet of which the solution forms a foam containing minuscule gas bubbles in the liquid. The bubbles grow and multiply when the stream moves away from the nozzle. Even after deposition on a substrate the beads continue to grow. This foam retains adhesiveness characteristics which are superior to those of the same adhesive when dispensed under the same conditions but without bubbles in the liquid.