GB1282876A - Process and apparatus for forming layers of setting plastics materials - Google Patents

Abstract

1282876 Coating apparatus GUTHRIE INDUSTRIES Ltd 10 Oct 1969 [14 Oct 1968] 48678/68 Headings B2E and B2L [Also in Division B5] An applicator die particularly intended for coating a substrate with resins made up from a reaction mixture containing a curing agent or catalyst, e.g. thermosetting polyurethane made up from a resin containing hydroxyl groups and an isocyanate, comprises members 20, 21, Fig. 3, sufficiently easily separable to allow cleaning of passages 25a-25d, 28 and 30 within the "pot-life" of the resin. As shown, members 20, 21 are hinged at 24 and passages 25a-25d, 28 30, formed wholly in member 21 to facilitate cleaning, are exposed on release of pneumatically operated clamps each having components 34-37 &c see also Fig. 6 (not reproduced), and pivoting member 21 downwardly about hinge 24, see also Fig. 7 (not reproduced). Passages 25a-25d, Fig. 4, are arranged to give equal flow-path lengths to the apices of triangular passages 28 which latter lead into pressure equalising and a relieving passage 30 immediately upstream of the die orifice 7, Fig. 3. The die orifice is defined along one side by die part 20a and is adjustable by rotation of screws 122 which are linked to part 20a. Further quick-release clamps are provided relatively near orifice 7 and comprise rods 50 tensioned against plates 53 by rotation of handles 57, see also Fig. 5 (not reproduced). Sometimes it is preferably to arrange one side of the orifice to extend lower than the other. In operation, the reactants are delivered to a mixer (4), Fig. 1 (not shown), via heated tubes (5, 6). On cessation of delivery, the applicator die, suspended from a trolley (83), is moved on gantry (80) to a position over trough (70), Fig. 7 (not shown), where it is opened. In modifications, the mechanical clamping means may be replaced by electromagnets and a relatively short die may comprise only one triangular passage 28. The substrate to be coated may be a floor over which the application is moved, but is normally web-like and is moved past the applicator. Permanent coatings, e.g. of foamed resin, may be applied to fabrics or carpets; alternatively the substrate may be of rigid or flexible foam. Laminated materials may be formed by pressing a second web onto the exposed surface of the coating and possibly also passing the assembly through a pair of nip rolls within the "pot life" of the reactive mix; as an example a tufted carpet may be backed using the applicator and have a second backing of, for example, hessian. Alternatively the coated substrate may be reversed and a second coating applied thereto. The coating may be heated, e.g. by infra red heaters, to promote the reaction and may be subsequently cooled and/ or dusted. Particulate material, for decorative or hard-wearing purposes, may be applied to the resin coating before it has set. To produce self-supporting sheets or films the substrate is provided with a release surface such as silicone rubber. Resins mentioned in addition to polyurethane are polyurea, polysulphide, polyester, epoxy, acrylic and silicone resin.