GB427538A - Process for coating the inner walls of flexible tubes or casings with a thin film-producing layer - Google Patents

Abstract

<PICT:0427538/IV/1> The inner walls of tubes, particularly of regenerated cellulose, are coated by introducing a film-producing material into the tube, squeezing out excess of the material and drying whilst blowing up the tube, the supply of gas for blowing up the tube being shut off from the coating device by subjecting the tube to pressure which gradually increases in the direction of movement of the tube, and then gradually decreases again. This effect is preferably obtained by passing the tube into and out of a column of water. Gelatine is the preferred coating material, but cellulose esters and viscous resin solutions also are referred to in this connection. The tube to be coated is led from a reel 18 and filled with gelatine solution between the rollers 4, 5 and 6 immersed in a bath of warm water or dilute glycerine. On leaving this bath the tube has excess of gelatine removed by passing it between a squeezing device 11, 12, the pressure applied being determined by a weight 17, and is then passed vertically into and out of a column of warm water or glycerine 2. The tube finally passes to a drying device wherein drying takes place with the tube in an inflated condition.