GB476959A - Improvements in the manufacture of granule-coated webs - Google Patents

Abstract

476,959. Granule - coated webs. TENNANT, W. J. (Carborundum Co.) June 19, 1936, No. 17130. [Class 60] In making granule-coated webs, the web passes. from the place at which adhesive is applied to that at which the granular material is applied through a chamber in which the atmosphere is regulated to control the condition of the adhesive coating. The controlled atmosphere may serve to maintain the adhesive in unchanged condition or to convert it into a suitable condition for receiving the granules, e.g. by altering its viscosity. As shown in Fig. 1, a web P passes over idler rolls 2, 3, 4, receives adhesive such as glue from roll 5 and then enters a chamber A in which the temperature is controlled by heating elements 11 which may be steam pipes or electrical heaters and the humidity is regulated by the introduction of water vapour from nozzles 12 of a supply pipe 13. Circulation of the air is maintained by a fan 14. After leaving the chamber a granular material is projected upwardly on to the downwardly facing adhesive surface of the web P in known manner. In a modification the granules are dropped on to the upper adhesive surface of the web. In a further modification shown in Fig. 3, the adhesive is applied by means of automatically controlled spray nozzles 27 in the chamber B and the desired vapour pressure is maintained by the evaporation of solvent contained in a vessel 29 provided with heating elements 30. If desired, further heat may be supplied by elements 31. Condensed solvent is removed by a drain 32. When water - soluble adhesives are used the spray nozzles are operated by warmed and humidified air and in the case of adhesives such as resin, lacquer or varnish, air laden with solvent, e.g. alcohol, acetone or benzol, is preferably used. Specifications 455,639 and 457,333 are referred to.