Stock material or miscellaneous articles – Sheet including cover or casing – Foamed or expanded material encased
Patent
1995-07-10
1997-04-01
Cannon, James C.
Stock material or miscellaneous articles
Sheet including cover or casing
Foamed or expanded material encased
428 92, 4283044, 4283099, 4283144, 442315, 442318, 442319, B32B 102, B32B 106, B32B 522, B32B 528
Patent
active
056163916
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a composite material having a substantially sandwich-like structure. This sandwich structure comprises two layers formed by threads mutually connected by pile threads.
2. Description of the Prior Art
A known composite material comprises two layers in the form of web layers, while the pile threads couple the two web layers. A composite material based on a three-dimensional web has the drawback, however, that the layers are substantially vapour and/or moisture-proof and are therefore unsuitable for use in contact with the human/animal body. In addition the use of web layers has the drawback when one or both of the web layers is provided with a matrix, that a closed layer is created which is not moisture/vapour-permeable. While it is the case that a composite material based on three-dimensional webs is vapour/moisture-permeable, it is insufficiently strong and rigid. This could be improved by covering knitted layers with flat strengthening materials, whereby they become impermeable. Kunststoffe, vol. 80, no. 9, September 1990, pages 1003-1007 discloses a composite comprising an additional covering layer for the provision of sufficient strength to a sandwich structure.
SUMMARY OF THE INVENTION
The invention has for its object to provide a composite material substantially not displaying the above stated drawbacks, which has transversal and/or lateral vapour and/or moisture-permeating properties and is suitable for use in connection to or in contact with the human or animal body. Critical for this application is the combination of stiffness-impact resistance-air permeability at the lowest possible weight.
This object is achieved by a composite material comprising a three-dimensional textile structure which comprises at least two textile layers which are located at a mutual distance and which are mutually connected by looped-round pile-threads, wherein at least one of the textile layers is embedded in a matrix and at least one of the textile layers is vapor/moisture permeable.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Optimal stiffness, dependent on the curvature of the composite material which may be in a number of directions, is achieved by adapting the architecture of the textile layers. In the case of a knitted material the cell size may vary from for instance 3-5 mm and the cell shape can be hexagonal or diamond-shaped. An additional increase in stiffness can be obtained by knitting stretched and/or weft threads into the knitted material layers.
An optimum impact resistance is obtained by a choice of the pile thread density and of the bending resistance properties of the pile threads. This latter can be achieved by increasing the moment of inertia of the pile threads, for instance by enclosing supporting yarns (glass, aramide, polyester etc.) with a thicker matrix layer of for instance a thermoset (after impregnation with a liquid) or a thermoplast (in which case the pile yarns are braided and/or spun and subsequently melted).
The skin compatibility is achieved optionally by the choice of the threads for the textile layer (knitted, web, non-woven material etc.) and optionally by filling a least a part of the space between both textile layers with an open or closed cell foam. This composite material can be joined to an adjoining other composite material by adhering thereon etc., and on the other hand the composite material can be integrated with other composite materials according to the invention by fusing or setting with thermosets respectively thermoplasts.
In preference the vapour/moisture-permeable textile layer consists of a knitted material layer because the knitted threads have a mutually curved form and, with curving in two directions, this does not result in tensions in the knitted material layers and the looped-round pile threads. An alternative to a knitted material layer is the use of a web layer. However, known web layers applied in three-dimensional textile structures are closed. The web layer can be so
REFERENCES:
patent: 5334442 (1994-08-01), Okamoto et al.
patent: 5395684 (1995-03-01), Robinson et al.
patent: 5413837 (1995-05-01), Rock et al.
patent: 5418044 (1995-05-01), Maliler
F. Horsch, Dreidimensionale Verstarkungsmaterialien fur Faserverbudstoffe, Kunststoffe, vol. 80, No. 9, Sep. 1990, pp. 1003-1007.
Amesz Willem
De Meyer Willy
Van Raemdonck Joris K. M.
Verpoest Ignace H. J. M.
Cannon James C.
K.U. Leuven Research & Development
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