GB803259A - Improvements in or relating to cellular structures made from paper and other sheet materials - Google Patents

Abstract

803,259. Laminates; honeycomb paper. DUFAYLITE DEVELOPMENTS, Ltd. Jan. 26, 1955 [Jan. 26, 1954; Jan. 29, 1954; June 23, 1954], Nos. 2412/54, 2808/54 and 18448/54. Classes 96 and 140. A structural honeycomb material comprises a stack of layers 11 of flexible sheet material, e.g. paper, produced by superimposing a number of separate layers or by folding a web of sheet material, adjacent faces of the material being adhesively secured together along a plurality of spaced parallel bands, the bands on opposite faces of each layer being staggered, and the coherence of the stack being rendered non- uniform over planes which intersect the layers in the direction of the bands by the inclusion of at least one layer of material which is inferior to the other layers as regards its mechanical strength and/or its adhesive affinity and/or by arranging the adhesive in a discontinuous distribution along the bands which leaves the bands with substantial adhesive-free portions arranged in rows which cross the faces and bands. The dissimilar material may be a single sheet in the stack or several sheets, e.g. alternately disposed. Various examples are given, e.g. a single sheet 14, Fig. 3, of tissue paper or regenerated cellulose may be incorporated in the stack. The layers 11 may comprise sheets or pairs of sheets of resinated and unresinated paper, resinated paper interleaved with polystyrene foil, unresinated paper with cellulose acetate, or resinated or unresinated paper with metal foil. Alternatively, each sheet 11 in the stack may itself be laminated, examples being paper-backed metal foil, metal foil between two resinated or unresinated paper sheets, paper coated on each surface with cellulose acetate or cellulose acetate or bitumin lying between two paper sheets. Instead of resinated paper, thermosetting resin coated paper or thermosetting resin laminated between two paper sheets may be employed, or the sheets 11 may be webs of asbestos or glass fibres. Each sheet 11 may have parallel series of perforations 22 in the spaces between the bands of adhesive, Fig. 10, to provide communication between adjacent cells in the completed structure. Where all the sheets 11 comprise unresinated paper, the completed stack, after cutting along lines perpendicular to the bands of adhesive, may be dipped edgewise into a bath of resin and subsequently cured, e.g. throughout its depth or along the margins C only, Fig. 12. Alternatively, the sheets 11 may be resinated in strips prior to stacking. Unresinated paper structures may be set in expanded condition by dipping in water or immersing in a steam bath, and subsequently dried with or without heat. Insecticide, fungicide, creosote or fire-proofing agent may be added to the water, or a thermosetting resin or a size, e.g. casein glue, may be added. Where the sheets 11 are paper containing a thermoplastic impregnant, e.g. polyvinyl acetate, the expanded structure may be set by heating and then by being allowed to cool or by treating with a solvent, expanding and drying. Where the paper 11 includes a thermosetting material the structure may be softened by a solvent prior to expansion. Where non-uniform coherence is produced by employing discontinuous glue bands 25 the stack 24 may be cut along lines 28, Fig. 13, or 30, Fig. 15, to produce structures the adjacent sheets of which are adhered together along marginal areas only, Fig. 13, or intermediate areas, Fig. 15. Structures so constructed may be readily bent after expansion to provide curved shapes. The distribution of adhesive 26 in the bands 25 may be such as to provide in the completed structure adherence between adjacent layers in some places at one edge, in some at the other, and in some intermediately, e.g. where the curvature of the structure varies from positive to negative throughout its length. The cellular structures may be surfaced with paper, ply or pulp board, metal, resinated asbestos or resinated glass fibre cloth, plaster board or synthetic sheet material. Where a sheet 14 of low adhesive affinity is employed, this sheet may form the base of the stack to facilitate removal of the stack from a platen on which the stack is erected. Specification 591,772 is referred to.