LAMINATED STRUCTURES

Abstract: Device (10, 70) and method of fabricating as lamination of one thermoplastics layer (42) heated to bond or merge with another thermoplastics layer (43) and melt flow in permeating another layer (21) if present by agency of radiation passing through said other thermoplastics layer (43) without melting same. Tubes can be erected and laminated on site to line existing pipes or conduits (40). Stiff or flexible sheets or webs (70) can serve as special composite tiles or panels, or as conveyor belts.

Description: TITLE: LAMINATED STRUCTURES DESCRIPTION TECHNICAL FIELD This invention relates to laminated structures including pipes, in particular connection with which this invention has arisen, but is applicable much more widely. BACKGROUND ART Supply piping for some utilities, such as water and gas (particularly) , should be leak-proof at prescribed internal pressures, whether as new installations or exist¬ ing installations after refurbishment by re-lining. My PCT Application No. GB95/02954 specifically discloses refurbishment using pipe of thermoplastics material, generally of about 25 mm or more wall thickness, first installed under-size in the host pipeline. Crystalline thermoplastics material of the re-lining pipe is softened then expanded for intimate fit with host pipeline by internal heating and applied gas pressure using a compact machine combining heating and gas pressuring further preferably with an electrical generator in a coaxial and concentric arrangement. Preferred absorption by the thermoplastic material of heat from infra-red radiation is followed by useful transparency at or about crystalline melt (without full melt) allowing effective self-regulation of heatmg/softening with advantageous replacement of thermoplastic memory as between original and new geometries . DISCLOSURE OF INVENTION Further scope is now seen for new or re-lming pipe of lesser wall thickness, and/or greater resistance to radial deformation, and/or easier installation without lead-m trenching, which it is one object of this invention to provide. According to one device aspect of this invention, pipe comprises consolidation or lamination of permeable material typically of structural or reinforcement nature permeated by one thermoplastics material of lower melting point than other thermoplastics material of a layer at least thermally bonded therewith. Start materials, including on-site, can be separate flexible layers of permeable reinforcement and amorphous thermoplastics materials readily juxtaposed typically with the one thermoplastics material between the reinforcement and the other thermo-plastics material for being melted for reinforcement-permeating flow by heat and pressure applied through and by the other thermoplastics layer without such flow melting thereof. Re-solidification in cooling the one thermoplastics material will be in its crystalline non- flexible state. Different density grades of the same basic thermo-plastics material, for example polyethylene, exhibit correspondingly different melting temperatures, also molten viscosities. Including when subjected to applied permeation pressure, low density grade material can be contained fully melted by higher density grade material, even above crystalline melt for the latter, which aids merging/fusing and achieving crystallmity throughout resulting consolidated materials. There may be plural successive layers of either or both of the amorphous thermoplastics materials, the provided thickness of the one being at least enough to permeate the reinforcement including extension as far as required beyond same if not provided or further provided at that side of the reinforcement) , and provision of the other being as desired or required, say for thickness (which can be from about 2mm) and strength (which can match or exceed existing pipes) of resulting pipe. Preferred reinforcement, at least as fabricated into a tube for desired pipe, has effectively continuous loops about its circumference successively along its length, which loops are of suitable form-constraming nature, conveniently substantially inextensible. Woven or braided materials with appropriate interlocking of threads to be longitudinal and circumferential are suitable, conveniently of high strength as available using carbon and/or glass fibres . According to one method aspect of this invention, heating to melt lower melting point thermoplastics material into permeation of, preferably through, permeable material typically of structural or reinforcement nature is done through higher melting point thermoplastic material without fully melting but preferably reaching crystalline melt for the latter, preferably using electromagnetic radiation, advantageously infra-red. Thin amorphous thermoplastics films/webs inherently at least partially transparent to infra-red radiation can be rendered suitably selectively absorptive by inclusions, such as particulate carbon black, m prescribed contents, to give a desired temperature profile for successive layers in consolidation by sa d heating. According to another method aspect of this invention, flexible layers of structural or reinforcement nature and lower and higher melting point thermoplastics materials are installed within each other, including any necessary taking round bends, where required prior to consolidation by heating from interior bounded by the thermoplastics of higher melting point held suitably erected, say by sufficient gas pressure, the latter conveniently further causing expansion of the higher melting point material for permeation of the reinforcement by melted said lower melting point material. Preferably, the layers are of closed tube form laid flat for such installation, conveniently by pressurised gas inversion, whether conjointly or individually in succession. Simple sheet stock is readily folded and edge- joined, usually heat welded, for laid-flat reeled supply to site. According to another device aspect of this invention, a flat flexible pipe component comprises conjoined tubes of outer lower melting point thermoplastics material and inner higher melting point thermoplastics material, the component being for installation flat and later erection, conveniently by gas pressure. Such pipe blanks are readily inverted by pressurised gas into an outer reinforcement tube laid in a trench or towed into a host pipeline to be refurbished. Further conjoining with outer reinforcement as supplied to site is also envisaged for laying in a trench or inverting as a whole into a host pipeline. Conjoining can conveniently be achieved by folding successively juxtaposed ordered sheets and seaming edges together. According to another device aspect of this invention, a flat flexible pipe component comprises associated tubes of reinforcement and thermoplastics material, usually lower melting point thermoplastics material. According to another method aspect of this invention component tubes of reinforcement and lower and higher melting point thermoplastics materials, or combinations thereof, are installed in an existing pipeline or conduit by successive inversion using pressurised gas. Permeability of the reinforcement can be overcome by prelammation to a impervious sheet of lower melting point thermoplastics material. More complex structures include one or more further reinforcement layers, say with associated thermoplastics materials layers as appropriate. Wider application of this invention can be highly advantageous, including to flat sheet or web forms that can have any desired degree of flexibility, say for use as conveyor belts, even be elastomeric; or can be stiff as may be desired or required for various special-purpose panels or tiles: indeed, any intermediate or further variant capable of at least partial fabrication as a laminate of which at least one layer is of a thermoplastics material capable of at least bonding to if not permeating another layer consequent to heating by application of radiation, preferably through another layer at least partially transparent to such radiation and not melted thereby, and further preferably itself becoming bonded onto said laminate say itself different from the first-mentioned other bonded or permeated layer and/or of thermoplastic material possibly a different grade of the same thermo¬ plastics material as said one layer. This first-mentioned other layer can be of a strengthening or reinforcing nature, or be no more than affording heat-generating function, say by nature or inclusions that absorb said radiation; indeed, even an all-thermoplastics laminate can be useful, its layers having differing features and functions, including transparency and/or sufficiently absorptive and/or heat flow, relative to said radiation and/or final product requirements etc. Results may be as a layer, tape, seal or whatever applied to same other article or product. Actual fabrication can advantageously be by way of roller means itself containing source means for said radiation and having relatively movable radiation- transparent peripheral engaging means for an assemblage of the layers of said laminate, specifically outer transparent layer thereof that will not heat enough to cause any sticking to the roller means. A single roller may be above or below one side of such assemblage of layers, usefully with a reflector at the other side or as an opposite outer layer of the assemblage. Double rollers can be similar to each other and/or [hotter] or either can include reflector means, the assemblage of layers passing through a nip between such double rollers. BRIEF DESCRIPTION OF DRAWINGS Specific implementation for this invention is now described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is an idealised section through an embodiment of finished pipe; Figures 2, B are outline perspectives showing one reinforcement structure and pipe parts assembly before on-site formation; Figures 3A, B, C are outline perspective and sectional views relating to making pipe components; Figures 4A, B schematically show stages of pipe parts installation in a host pipeline; Figure 5 schematically shows pipe formation; Figures 6A, B are outline sections for variant layering and indicate more complex pipe structures; and Figures 7A,B are outline sectional and side views of a two-roller sheet/web fabrication apparatus and one of its rollers, respectively. BEST MODES FOR CARRYING OUT THE INVENTION In the drawings, idealised pipe 10 of Figure 1 is shown with permeable reinforcement 11 with lower melting point thermoplastics material 12, typically low density poly-ethylene, outside, and higher melting point thermoplastics material 13, typically high density polyethylene, mside. Any boundary between the thermoplastics materials 12 and 13 will be against mside of the reinforcement 11 or spaced therefrom. The thermoplastics material 12 will have been melted for permeating flow at least into, shown as through and embedding, the reinforcement 11, by way of heat, preferably produced by infra-red radiation, applied through the material 13, The latter serves both to contain the material 12 when melted and to apply pressure, whether mechanically or by compressed gas, conveniently air, to expand the material 13 to force the desired permeation and satisfactorily bond to the material 12. In practice, accompanying heating of the material 13 can achieve its crystalline melt temperature, thus facilitating stretching, replacement of geometric memory, and crystallisation at cooling along with crystallising of re-solidifymg material 12, thus fusion or merging beyond mere thermal bonding between the materials 12 and 13. Figure 2A incompletely indicates permeable reinforcement as woven braid or hose 21 in the form of successive circumferential closed substantially extensible loop or hoop threads 22 and interwoven/ interlocked longitudinal threads 23. For usual circular section pipe, this tubular (when erected) reinforcement 21 should match the desired external diameter of pipe 10 and/or internal diameter of pipeline to be re-lmed less such thickness of low melting point thermoplastics material 12 as is to be extruded through interstices of the preferred braid or hose 21 and/or (typically mcludmg) any desired tolerance, though it will be appreciated that preferred flexibility along with inherent lay-flat/fold g capability can make such tolerance for re-l ing purposes very much a matter of choice. High structural strength and stability arises from use of suitable fibre materials, including carbon and/or glass fibres, and high uniformity from seamless structure, though neither of seaming nor use of other than textile materials is ruled out, even of inflexible or tendedly not deformed type for pipe to be factory-made in lengths for purposes perhaps other than primarily envisaged herein. Figure 2B shows erect state of the preferred reinforcement 21 along with successively internal tubes 32 and 33 of lower and high melting point thermoplastics materials to produce the layers 12 and 13 of Figure 1. Either or each of the tubes 32 and 33 may, in practice, comprise plural sheets films or webs, thin such bemg the form in which highly flexible amorphous thermoplastics such as poly-ethylene are readily made and available (relying on rapid coolmg/quenching at small thickness to avoid crystallised forms) . Satisfactory, if desired ordered (see more below) , merging/fusion and melting is readily achieved. One low density (42) and two high density (43) polyethylene webs are shown m Figure 3A prior to folding opposite side edges inwards and seaming together as shown at 44 in Figure 3B, say by hot blade fusion. Such has merit m itself as a flexible lay-flat pipe component readily supplied in long-length reel form, say for installation by pressurised gas (usually air) inversion into a reinforcement tube 21. Further as-supplied association with such reinforcement tube is shown m Figure 3C, then mvertible as a whole into a pipeline to be relmed, or simply laid mto a trench, and erected later for processing as will be described. If bare, the reinforcement tube 21 will need towing mto place, say (see Figure 4A) mto a pipeline 40 to be re-lmed, conveniently off its own reel (not shown) down a manhole 41 into the pipeline 40 proper. If not using a composite component (Figure 3B) , that will be followed by low density polyethylene flim(s) /web(s) 42 off reel 42R, say inserted through an inversion nozzle 45 with film/web flange 46, and control valve 47 and connection 48 for compressed air; and, see Figure 4B, by high density polyethylene fιlm(s) /web(s) 43 similarly taken off reel 43R. Multiple double-layer insertion of films/webs 43 is indicated in Figure 4B, requiring puncturing/cutting of doubled-over end, see 43E. For 0.5mm film/web thickness, five such double insertions would contribute 5mm to wall thickness. Installation and/or erection of flexible reinforcement tube 21, perhaps particularly for re-lming an existing underground pipeline 40, can be facilitated by its prior association (mcludmg bonding if desired) with a or the film/web 42 of low density polyethylene, perhaps preferably on its inside to avoid trapped air bubbles, though not essentially as all low density polyethylene will intentionally melt and probably be of sufficiently low viscosity to permit bubble expulsion through it. Once installed, whether in a trench or host pipeline, the above-described pipe parts can be processed on site and from within by a machine generally related to the machine of above-mentioned UK/PCT patent application. Thus, Figure 5 shows part of such a machine 50 along with upper parts 21, 42, 43 of the pipe. The machine 50 has, n generally coaxial and concentric relation, outer transparent cover 51 over an elongate annular array of infra-red lamps 52 and reflector 53, end compressed gas driven turbine 54 drawing pressurised gas, usually air (but feasibly inert, such as carbon dioxide, for safety reasons), further serving for cooling the lamps 52 and/or reflector 53, further inner electric turbo-generator 55 if preferred to electric supply 56. The machine 50 is further shown with pressurised gas supply conduit 57, tow lme 59 and wipers 58A, B for containing infra-red heating radiation at 60, pipe parts erection and inter-layer air expression, and smoothing m consolidation/lamination of thermoplastics materials 42 and 43. As a gas compressor, of course, output of turbine 54 might be fed to inflate and pressurise the pipe parts at/over the wiper 58A and/or in the heating space (60), as well as providing indicated (61) cooling of consolidated/ laminated pipe parts. Another gas-erection alternative would be for part of pressurised gas supply 57 to be fed between wiper 58A and another upstream wiper or back- pressure damper. It is even feasible, say m a further machine combination, for low density polythene to be extruded in situ over the wiper 58A. With reinforcement 21 outermost, low density polyethylene 42 against it, and high density polyethylene 43 innermost, the latter will be heated over its crystalline melt temperature (and be consolidated) with the low density polyethylene 42 going molten but still contained to flow mto and through the reinforcement 21 with and trapped air bubbles escaping, whether aided only by wiper 58A or (also) by gas pressure. High viscosity of the high density polyethylene 43 effectively precludes semi-molten dripping. Heat absorption by the reinforcement (carbon fibre or colloidally or ironically coloured glass fibre) assists maintaining molten state. The reinforcement loops or hoops 23, being strong and substantially extensible preserve desired pipe size, the high density polyethylene 43 expanding to a maximum of intimate keying contact therewith, but advantageously effectively continuous ultimately rigidly crystalline consolidation with the low density polyethylene 42 in a final reinforced pipe structure of high strength all round, including longitudinally, even with quite thin wall, typically from 2mm to 5mm, but more if desired, see further below. Cooling consolidated pipe parts, indicated at 61 from the turbine 54, is typically fully effective in as little as ten minutes after machine passage. Partial transparency and infra-red absorptivity of the polyethylene pipe parts is configurable by way of selective inclusions, such as carbon black, to give desired thickness temperature profile durmg processing, mcludmg for appropriate pressurising action. Turning to Figures 6A and 5B, layering variants mclude an inner one (43A) of high density polyethylene fιlm(s) /web(s) having infra-red absorption enhancement greater than others (43B) which can be of unadjusted transparency; and low density polyethylene film/web 42A applied outside the reinforcement 21, feasibly further along with outer high density polyethylene 43C. Repetition of layering combinations is indicated by sets of ditto marks with and/or outside sequences actually shown. repeated layering may, as desired or required, vary as to number and thickness of constituent fιlm(s) web(s) . Figures 7A, B show manufacture of laminate sheet or web 70 having at least one inner permeable layer 71, shown as a single dashed line, between melt-flow thermoplastics layers 72A, B and opposite outer layers 73A, B. The outer layers 73A, B may also be, preferably are, of thermoplastics material but of higher melting point than the layers 72A, B and sufficiently transparent to operative radiation, conveniently infra-red, to cause the medial layers 72A, B to soften or at least partially melt and permeate the inner layer(s) 71 without such heating of outer layers 73A, B as could be detrimental to operation using one or more rollers 75. Sufficiency of heating of the medial layers 72A,B may be promoted/procured by either or both of absorptive nature or inclusions in those layers 72A, B and nature or ιnclusιon(s) of the inner layer(s) 71. A practical and advantageous roller 75 comprises a frame 76 suitable for a conveniently tubular structure in which frame a conveniently elongate single or multiple radiation source (s) 77 is shown supported, whether axially central as indicated or otherwise say below and/or to each side of a central frame part, inside a transparent cylindrical part or lens 78 in suitable bearings 79A, B to ends 80A, B of overall roller 75 so as to permit free rotation of the part or lens 78. Figure 7A shows two rollers 75X, Y with a nip through which assemblage 70 of the layers 71-73 passes usually is suitably drawn a rate related to power of the radiation source (s) 77 and desired permeation/bonding of the layers 71/72/73 to avoid the outer layers becoming hot and sticky. Dashed lines show various infra-red ray paths including reflections at either surface of the lens part 78 and/or specific arcuate reflector(s) 81 shown with the preferred rollers 75X, Y. It is to be appreciated that the inner layer 71 could be omitted and/or the lamination assemblage be asymmetric, including wholly one-sided, see Figure 7B, for use with a single roller 75, say with outer non-meltmg layer 73 out- side medial or inner melt flow/bondmg layer 72, with or without a permeable etc layer 71 and/or a further reflect¬ ing layer 74. The result of such fabrication can be a useful stand¬ alone product, whether of flexible even elastomeric type as might be used for conveyor purposes, or stiffer even rigid type as a special performance composite panel or tile. Alternatively, suitable addition may be made to some other product, for example bonding onto a thermoplastic outer layer of pipe hereof as a tape, seam or seal, see for example copending patent application GB 96/14659. Generally, control of energy absorption and heat production in and/or for the layers 71, 72 is a matter for selection of radiation and/or inclusions. Highly efficient processing is attainable relative to minimal applied heat requirements operative mainly if not solely at lamination interfaces and/or melt flow layers. Moreover, continuous or discrete lengths of product may result with advantages dimensional stability etc. Use of selected appropriate thicknesses and positions for more absorptive thermoplastics layers has quite general application, including affecting ultimate positions/ embed¬ ments of reinforcement (s) . At least for thermoplastics layers placed outside permeable reinforcement(s) , perforation, preferably microscopic sized (say by electric discharge or laser techniques) can significantly aid dispersal of mter-layer gas entrapments. For some applications, it is envisaged that useful structures can result with low density/low melting point material omitted.

Claims: CLAIMS 1. Method of making device comprising laminations of thermoplastics layers of different melting points and another permeable layer, the method comprising heating to soften/melt the lower melting point thermoplastics material mto permeation of, preferably through, the permeable layer which heating is done through the higher melting point thermoplastic material without fully melting but preferably reaching crystalline melt for the latter. 2. Method accordmg to claim 1, wherem heating is by electro-magnetic radiation, advantageously infra-red. 3. Method according to claim 1 or claim 2, where start materials comprise separate layers of permeable material and amorphous thermoplastics materials juxtaposed with the one thermoplastics material between the permeable layer and the other thermoplastics material for melting and permeating flow by heat and pressure applied through and by the other thermoplastics layer without flow melting thereof. 4. Method according to claim 3, wherem either or both of the amorphous thermoplastics materials comprises plural successive layers, the provided thickness of the one being at least enough to permeate the permeable layer including extension as far as required beyond same if not provided or further provided at that side of the permeable layer, and provision of the other being as desired or required for thickness and strength of resulting pipe. 5. Method according to claim 3 or claim 4, where re- solidification in cooling the one thermoplastics material is m its crystalline non-flexible state. 6. Device comprising consolidation or lamination of permeable layer, conveniently structural or reinforcement, permeated by one thermoplastics material of lower melting point than other thermoplastics material of a layer at least thermally bonded therewith. 7. Device or method according to any preceding claim, wherem the one and the other thermoplastics materials comprise different density grades of the same basic thermo¬ plastics material, for example polyethylene, exhibiting conveniently different melting temperatures, also molten viscosities. 8. Method according to claim 7, wherem the low density grade material is contained fully melted by higher density grade material, even above crystalline melt for the latter, and aids merging/fusing and achieving crystallmity throughout resulting consolidated materials. 9. Modification of device or method according to any preceding claim, wherem the permeable layer is omitted and the resulting device is a heat bonded lamination of two thermoplastics layers. 10. Method or device according to any preceding claim, wherein the device is tubular. 11. Method or device according to claim 10, wherem said permeable layer affords reinforcement by way of effectively continuous loops about circumference of the tubular device successively along its length, which loops are of suitable form-constraming nature, conveniently substantially extensible. 12. Method according to claim 10 or claim 11, wherein lining of an existing pipe or conduit involves initially flexible layers of reinforcement and lower and higher melting point thermoplastics materials as installed with each other, including any necessary taking round bends where required, prior to consolidation by heating from interior bounded by the thermoplastics of higher melting point held suitably erected, say by sufficient gas pressure, the latter conveniently further causing expansion of the higher melting point material for permeation of the reinforcement by melted said lower melting point material. 13. Method according to claim 12, wherem the layers are of closed tube form laid flat for such installation, con¬ veniently by pressurised gas inversion, whether conjointly or individually m succession as sheet stock folded and edge-joined, usually heat-welded, for laid-flat reeled supply to site.

Inventors: WOOD JOHN, WOOD, JOHN
Applicants: WOOD JOHN, WOOD, JOHN
Application year: 1996
Main classification: B29C63
IPC codes: B29C35, B29C63, F16L55