Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1989-05-22
1991-06-04
Ball, Michael W.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
523097, 264 465, 264 467, 425817R, 156245, 4283099, 4283191, B32B 520
Patent
active
050211080
DESCRIPTION:
BRIEF SUMMARY
This invention is concerned with the manufacture of laminated panels having a core of cellular plastics material and an apparatus for the manufacture of such panels.
Throughout the specification reference is made by example to panels having a core formed from a liquid foamable polyurethane resin. It should be understood however that the invention concerns any liquid foamable plastics material capable of solidifying to form a stable core material to which one or more outer skins are adhered.
Lightweight panels having cellular plastics cores sandwiched between durable outer skins of sheet plastics, metal, timber cementitious materials and the like have found favour as thermal insulation members in cold rooms, cold storage warehouses and building structures located in adverse climates. Typically such insulating panels comprise a core of open or closed cell polystyrene or polyurethane foam.
Polystyrene foam possesses a number of disadvantages as an insulating material. In terms of thermal efficiency it is inferior to polyurethane foam as approximately 50% greater panel thicknesses are required with polystyrene foam panels for equivalent thermal insulating qualities.
When open cell polystyrene foam panels are used for say a cold room or freezer, the panels absorb water and ultimately the panels become effectively a solid block of ice. This substantially reduces the thermal efficiency of the panels and due to the weight increase, substantially stronger support structures are required. Another disadvantage is that the outer surface of the panel exposed to ambient conditions is constantly wet with melted ice and this can lead to decay or corrosion in steel support structures and steel or timber panel skins.
Of recent times a closed cell polystyrene foam has become available but it is substantially more costly than prior art open cell polystyrene foam. While closed cell foams substantially alleviate the problem of water absorption, thicker panels are still required.
Polystyrene foam cored panels are costly to manufacture as the core slabs are cut from large slab stock and then adhered to the outer skins in a press. The high capital costs associated with large presses tends to limit the size of polystyrene foam cored panels.
Polyurethane foam cored panels have found increasingly greater acceptance as insulating panels due to ease of manufacture, greater strength and superior insulating qualities.
Generally speaking polyurethane foam cored panels are formed by injecting between spaced skin members an admixture of a polyether resin, a di-isocyanate material and an additional blowing agent such as Freon 11 or Freon 12. The opposed skin members are held either vertically or horizontally in a press and are spaced by removable timber or steel members located about the periphery of the skin members The peripheral members act to form mould closures to define an enclosed space between the skins. Alternatively, non-removable peripheral and intermediate members made from polyurethane foam may be employed to act as spacers for the skins and to act as mould closures.
Although high quality foam cored panels having a variety of skin finishes may be produced in this manner, there are nevertheless some disadvantageous aspects associated with the manufacture of such panels.
Polyurethane foam cored panels produced by prior art methods are generally limited in length to about, say, 10 metres. This is due partly to the high capital cost in manufacture of a press capable of withstanding an internal pressure of 5 to 6 p.s.i. as the foam undergoes expansion. The other major limiting factor is that transportation of panels in excess of 10 metres in length is difficult, costly and often prevented by traffic authorities.
Accordingly it is an aim of the present invention to overcome or alleviate the problems associated with prior art apparatus and processes in the manufacture of polyurethane foam cored panels.
According to one aspect of the invention there is provided an apparatus for manufacture of foamed plastics laminated panels having at l
REFERENCES:
patent: 2576073 (1951-11-01), Kropa et al.
patent: 4012186 (1977-03-01), Ramazzotti et al.
patent: 4793793 (1988-12-01), Swenson et al.
patent: 4955800 (1990-09-01), Rothwell et al.
Ball Michael W.
Bergqvist Coral Irene
Osele Mark A.
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