Plastic and nonmetallic article shaping or treating: processes – Pore forming in situ – Composite article making
Patent
1992-06-11
1994-01-04
Kuhns, Allan R.
Plastic and nonmetallic article shaping or treating: processes
Pore forming in situ
Composite article making
264 466, 425812, B29C 6722
Patent
active
052757692
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to methods of manufacturing laminated articles, in particular to laminated articles that are used as a seat cushion or a seat back support, and more particularly to vandal or damage resistant seats for use on public transport.
A number of vandal resistant seats offered for use in public transport in recent years have been criticised because they are too hard and lack comfort, for example the seat described in Australian Patent Application No. Application No. 594,037 (52495/86) uses a polyurethane (V8080) and Moca. Supplied by Uniroyal Aust. Pty. Ltd. this provides a high tensile elastomer with a short "A" hardness of about 75-85 which is used in conjunction with a wire mesh with a wire diameter 0.75 mm. The wire in this construction presents a reasonably stiff form without the elastomer. The addition of the elastomer makes a very stiff and board like seat. The elastomer is hard when moulded into a seat without the wire reinforcement. While mesh of a chain-mail type is mention it would do little to improve the flexibility in this case unless a softer more flexible elastomer were to be used. Moreover, this process uses a material that needs to be kept at elevated temperatures, i.e. in excess of 100.degree. C. and requires a long curing period, for example 2 hours plus post curing for a further 8 hours. Vickers Xatal AU-B-12028/88 describes a solid form seat pan covered by a flat sheet which illustrates the difficulty experienced by others attempting to mould vandal resistant materials into seat shapes and retain the flexibility necessary for some degree of comfort. The method of moulding seat shapes appears to have been abandoned in favour of a solid seat pan.
U.K. Patent G.B. 2,041,742 to J. L. Danton and M. Duret, also teaches a wire reinforced construction, while this produces a softer and more flexible seat it has other manufacturing limitations in that only flat sheets appear to be produced by this method. J. L. Danton and M. Duret in European Patent No. 0,201,419 FIGS. 1-8 describe a method by which a three dimensional seat shape as opposed to a flat sheet may be made. This is done by fixing or moulding the previously manufactured sheet into a rigid plastic or metal frame. Unfortunately a flat sheet fixed in this manner tends to become stiffer unless it can elongate and flex which of course this material cannot. A somewhat hard and uncomfortable seat material results.
Other methods published on the manufacture of vandal or damage resistant seats e.g. U.S. Pat. No. 3,647,608, D. S. Enlow describes a method for producing a softer seat. However it has been found that seats manufactured by this method provide little resistance to damage by puncturing, and are not difficult to slash because the article is made of a foam in the density range that would normally be used for seating i.e. 35-60 Kg. per cubic meter, and reinforced by unconnected randomly oriented wires or metal fibers. Foams of this type have relatively low tensile strength and when used in combination with unconnected wires are not difficult to hack and pull apart, therefore seats manufactured by this method present only limited resistance to attack by vandals. D. S. Enlow in this invention did not consider damage that may be caused by fire from either large or small ignition sources. The overall resistance of articles made by this method are therefore limited.
The current favoured method of manufacturing a vandal resistant seat involves producing a wire reinforced microcellular urethane elastomer seat form, mounted on a board and supported on a fire retardant foam. The seat form then has to be covered by a woollen fabric which is attached to the seat form in a manner that makes the fabric as difficult as possible to remove or damage. The fabric is treated with at least three heavy coats of adhesive. The seat form is also treated with adhesive, and the adhesive is allowed to dry. The seat form and the adhesive coated woollen fabric are then placed in an infra-red oven and heated until tacky to reactivate the adhesi
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Derwent Abstract Accession No. 88-202002/29, Class Q39, (Honda Motor IND KK) Jun. 11, 1988 (11.06.88).
Derwent Abstract Accession No. 88-202003/29, Class Q17, (Mitsui Toatsu Chem Inc) Jun. 11, 1988 (11.06.88).
Henderson's Industries Pty. Ltd.
Kuhns Allan R.
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