Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including interlaminar mechanical fastener
Patent
1995-01-04
1996-07-02
Bell, James J.
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including interlaminar mechanical fastener
428225, 428247, 428253, 428254, 428263, 428285, 428299, 428301, 428919, D03D 300
Patent
active
055320520
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to camouflage material having a radar screening effect and comprising warp-knitted fabric in which at least part of the yarn in the fabric contains metal fibres.
U.S. Pat. No. 3,733,606 discloses camouflage means which function against radar reconnaissance, and also discloses a suitable surface resistivity in this regard. It is also known in this context to sometimes include metal wires or filaments textile yarns, such as cut pieces of thin metal wire or filament which are spun together with other fibres, either natural or synthetic fibres, to form a yarn which is later used as the warp and weft yarn in weaving processes. A good camouflaging effect is achieved when the surface resistance is suitably balanced, a practical standard in this regard being 300 Ohms per square. In certain cases, however, a lighter and more airy fabric is desired, which cannot be achieved by weaving, therewith leaving the alternative choice of knitted fabrics. The alternative possibility of weaving a wider mesh is not a suitable alternative, since the yarns will slip and slide unless glued together. Furthermore, a woven fabric cannot be draped as well as or will not fall as well as a knitted fabric.
U.S. Pat. No. 4,064,305 discloses knitted camouflage material. This material, however, has been devised with the intention of improving the wear properties and the stability properties of the material in relation to woven fabrics with regard to the radar defeating properties of the material when the material is in folds or is creased. According to this patent specification, the usable radar properties are achieved by a stretching process followed by fixation to a supportive sheet.
An object of the present invention is to provide a light-weight knitted fabric which can be used for camouflaging purposes, either as it is or when leaf-cut in the manner disclosed in the first-mentioned U.S. patent specification. Another object of the invention is to provide a warp-knitted fabric which exhibits from the beginning uniform radar reflexion and transmission respectively, as far as the polarization direction is concerned.
According to one particular aspect of the invention, an object is to provide a ready knitted fabric which exhibits good radar properties and which is effective in the infrared range, by "knitting together" or union knitting with a sheet or layer that reflects in the infrared range.
These objects of the invention and advantages afforded thereby are achieved in that in a camouflage material of the kind defined in the introduction the metal yarn containing the metal fibres is inlaid with a lay-out technique such that the sum of the extensions of the yarn will be essentially the same in each direction in the plane of the textile.
Expressed schematically, this means that it shall be endeavoured to produce relatively long float stitches with the yarn containing the metal fibres. It should also be endeavoured to obtain a knitted structure which gives low elasticity.
Yarn in which conductive material has been spun is relatively expensive to produce, and it is therefore suitable to lay this yarn in a fabric of some other kind, using conventional yarn as a carrier, or optionally, according to one variant, to knit-in a layer, which may be a gauze layer (nonwoven) provided with a metal layer, for instance a vapour deposited aluminium layer. This will also result in a less elastic fabric.
In order to obtain a visual camouflaging effect, it is suitable to colour the knitted material in patches. This can be achieved advantageously by pattern spraying with a dispersion water-based paint, which when drying and heated to a temperature of, e.g., 180.degree. C. for 30-40 seconds, will form a chemical bond with the fibre.
If the material is to be included in a net, it is suitable to leaf-cut in the manner described in U.S. Pat. No. 3,069,796, and fasten the material to a supportive net structure in a known manner. A quilting technique is preferred in this regard.
The invention will now be described with reference to exe
REFERENCES:
patent: 3069796 (1962-12-01), Ruter
patent: 3733606 (1973-05-01), Johansson
patent: 4064305 (1977-12-01), Walin
patent: 4671988 (1987-06-01), Dowell
Eng Kjell
Wallin Erik
Barracuda Technologies AB
Bell James J.
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