Patent GB-856389-A (GB)
Title: Process and apparatus for manufacturing impregnated bonded fibrous materials
Inventor: ROBERTS DOUGLAS
IPC: C08J9/42
Filed: 1957-12-24
Abstract: <PICT:0856389/IV (c)/1> A process for manufacturing impregnated woven or non-woven fibrous sheet material consists in applying an impregnant in the form of a foam on to one surface of a fibrous sheet material and in applying suction to the opposite surface of the sheet to suck the impregnant into the sheet.  As shown, a web 2 of non-woven fibrous sheet material is produced by an airlaying machine 1 and carried on the surface of an endless perforated conveyer belt 3 past a doctor blade 4 behind which is applied a foamed impregnating compound from a foaming machine 5 through nozzle 6.  A plough, not shown, is arranged at each end of the doctor blade 4 to confine the foamed impregnant to the width of the material to be covered. The foamed impregnant is applied as a coating spread on the upper surface of the web 2, which is then fed past an aperture 7 arranged under the conveyer and extending across its width, whereby suction may be applied to the opposite surface of the web to which the impregnant is applied and whereby the latter is sucked into the web.  Suction is produced by extractor fan 8.  The degree of suction applied to a given area can be varied by means of shutter 7a; and also by varying the speed of the extractor or of the conveyer.  The impregnated web is then passed through a drying machine 10 consisting of a convection air dryer; and the dried web is wound on a roll 11.  Prior to treatment with the foam, the fibrous material may be permeated with a vapour or fine mist or spray of a liquid which is subsequently solidified to impart rigidity during spreading and impregnation. Suitable impregnants are aqueous based compounds of natural or synthetic rubber, elastomeric materials with an aqueous or solvent base, vinyl resins, polyester resins, waxy hydrocarbons, aqueous dispersions of polythene or the constituents for forming a polyurethane foam within the fibrous sheet material.  Suitable fibrous materials are webs of natural or synthetic fibres or mixtures thereof, having random parallel or cross-laid fibres; felt materials, sheets or webs of curled hair; fibrous boards; and woven materials such as carpeting and fabrics.  The fibrous sheet material may consist of two or more sheets or webs of the same or p  of different materials, which become bonded together upon introduction of the impregnant to form a product of multi-layer or laminated construction.  Prior to impregnation a non-woven web may be needled, to constitute the mass of fibres, either by itself or through a supporting fabric.  To impregnate the fibrous material with the foam a combination of suction applied to the non-coated side of the fibrous material and an additional gas pressure on the coated side may be employed.  Examples disclose the impregnation of webs of acetate fibres, rayon felt, rayon felt material incorporating a woven hessian layer in its thickness, glass fibres, synthetic fibres and waste fibres; with natural rubber latex, reclaimed rubber dispersion, butadiene methacrylate polymer, unplasticised polyvinyl acetate, resorcinal formaldehyde resin, phenol formaldehyde resin, urea formaldehyde resin and with the constituent substances of polyurethane foam (i.e. a polyester or polyether resin and a di-isocyanate mixed together and foamed, together with a modifier and an emulsifier). An embossed pattern or wording may be applied to the impregnated fibrous material by passing it through embossed or engraved rollers after the impregnant has been at least partially dried.