Method of applying adhesive to porous materials

摘要

A method of coating the surface of semi-rigid porous materials such as open cell foam or fibrous compositions with a thermoplastic adhesive in powder form which will reactivate. The powdered adhesive in a size range of 0-600 microns will remain on the surface of such materials even when cell diameter of the foam or space between fibers is larger than adhesive particle size. High porosity is maintained in the coated product. First a thermoplastic adhesive in powder form is dispensed uniformly onto the surface of a carrier belt which is coated with a release agent and is moving continuously. The adhesive advances to a preheating station where the adhesive is plasticized and will adhere to the carrier belt to prevent movement, after which the foam or fibrous material is placed on the adhesive which is adhered to the belt. The adhesive and material advance to a second heating station where the adhesive is fully melted to allow the adhesive to bridge cells in the foam or space between fibers. The material and adhesive then advance to and through a cooling station where temperature of the adhesive and material are reduced to allow the adhesive to resolidify and the composite to release from the carrier belt and exit the machine.