Patent GB-1232650-A (GB)
IPC: B29C41/00
Filed: 1968-08-20
Abstract: 1,232,650. Coating with particulate material. SALADIN A.G. 20 Aug., 1968 [20 Nov., 1967], No. 39700/68. Heading B2E. [Also in Division D1] A method of applying particulate material to one or both sides of a backing material to form a permanent coating thereon, comprises spreading the particulate material onto a moving conveying surface having a form which serves to distribute the particles in accordance with the intended distribution of the coating on the backing material, the conveying surface brought into contact with the backing material and the particulate material is heated to a temperature at which it becomes adherent by application of heat to the particles solely on the side remote from the conveying surface. The heat may be transferred to the particulate material by heat exchange with a moving surface and the heat may be transferred to the particulate material while it is being conveyed on the conveying surface. The heat may be transferred from a heated moving surface to the backing material, and from the backing material to the particulate material. The backing material may be removed from contact with the conveying surface at a position in the vicinity of a further heated surface. The conveying surface may be cooled at least in the region where the particulate material is spread onto the conveying surface. The particulate material may be spread onto a continuously moving endless conveyor surface bearing surface recesses arranged in predetermined distribution, doctored to distribute the particles among the recesses, the conveying surface and backing material contacted, and heat passed through the backing material to render the particles adherent whilst maintaining the conveying surface at a temperature at which there is no tendency for the particles to adhere thereto. Backing materials specified are sheets, strips, bands, and webs of textile, paper, cardboard, knitted and woven fabrics, slubbing, wadding, fleeces, porous and non-porous foils, of for instance plastics or synthetic resin. Apparatus for carrying out the method comprises a storage container for particulate material, means for spreading the particulate material onto a recessed conveying surface, e.g. the external peripheral surface of a rotary drum, a pressure roll for applying a backing material to be coated against the conveying surface, and means for maintaining the roll at a temperature above that of the conveying surface. Cooling means may be provided in the vicinity of the spreading means, and also for cooling the conveying surface. Means may be provided for heating the conveying surface to above room temperature. A roll provided with heating means may be disposed adjacent the conveying surface and is positioned so as to contact the backing material before the latter contacts the conveying surface. At least one further guide roll for the backing material is provided and at least one of these rolls may be associated with heating means and is positioned so that the backing material passes around it as the material disengages from the conveying surface. A heating device, e.g. an infra-red radiator, may be positioned downstream of the further heated roll to heat the coated backing material.