Stab resistant insert with steel cords and non-woven textile
A stab-resistant insert (10) for protective textile comprises: at least one metal layer of a fabric of metal wires or metal cords (12); at least one textile layer (14, 16) The textile layer is in contact with and is connected to the metal layer. The textile layer comprises a non-woven material (14, 16) The stab-resistant insert combines a high level of stab-resistance with a high degree of comfort.
Latest N.V. BEKAERT S.A. Patents:
The present invention relates to a stab-resistant insert for protective textile. The stab-resistant insert comprises at least one metal layer and at least one textile layer. The present invention also relates to a protective textile comprising such a stab-resistant insert.BACKGROUND OF THE INVENTION
Protective textiles are becoming increasingly important as violence is increasing and is frequently taking forms as attacks on human persons with daggers and theft of luggage with knives in canvasses.
Synthetic fibers such as aramid fibers and high-density high-molecular weight polyethylene fibers have proved to be suitable for bullet-resistance. With respect to stabs such as knives and daggers, however, these fibers only have a poor performance. This is due to the inherent weakness of these synthetic fibers—and of all synthetic fibers—when it comes to transversal resistance. Metal, and more particular steel, has more resistance to radial compression.
The prior art has already recognized this property of metal and steel. EP-A2-0 769 671 discloses an anti-stab material with a set of metal strands which are secured to a non-metallic support fabric. The metal strands are unidirectional.
U.S. Pat. No. 5,883,018 discloses an optimization of the metal strands for use in anti-stab material. Steel cords with two or more different twisting angles are used to increase the potential to stop penetrating knives.
WO-A1-98/45516 discloses an anti-stab material where steel cords form a lattice, i.e. where both the weft and warp are formed by steel cords.
DE-U1-200 07 820 discloses a combination of anti-stab material and ballistic material. The anti-stab material is formed by a chain mail. Such a chain mail has the advantage of being very flexible, but has the disadvantage of having no form stability. In order to give form stability to the anti-stab material, the chain mail is fixed or bonded at the edges to a non-woven textile material. In ballistic situations if penetrating bullets break the chains of the chain mail into fragments, the non-woven material catches the fragments in order to prevent these fragments from penetrating into the body.
Conflicting requirements are always put on body armor and protective textile. On the one hand, comfort requirements push the designers towards the use of less material. On the other hand, safety standards increase the amount of impact absorbing and anti-stab materials.SUMMARY OF THE INVENTION
It is an object of the present invention to avoid the drawbacks of the prior art.
It is another object of the present invention to provide for a material which provides both comfort and safety for protective textiles. It is also an object of the present invention to provide for interaction and synergy between metal and textile.
According to the present invention there is provided a stab-resistant insert for protective textile. The insert comprises at least one metal layer of a fabric with metal cords or metal wires and at least one textile layer.
The textile layer is in contact with and is connected to the metal layer. The textile layer comprises a non-woven material.
The terms “non-woven material” include fibrous structures made by such processes as dry, wet, or air laying, needle-punching, spun-bond processes, and hydro-entanglement. The term non-woven material excludes woven, knitted, and tufted structures. The terms “non-woven fabric” refer to a fabric the fibers of which are either mechanically entangled or chemically bonded to each other.
The use of the non-woven material which is connected to the metal layer leads to a stab resistance.
The metal wires or cords of the metal layer are usually of a plain carbon steel or a stainless steel. In case of carbon steel, the wires and cords are preferably covered with a corrosion-resistant coating such as zinc or a zinc alloy, such as a zinc aluminum alloy.
In the fabric of the metal layer, the metal cords or metal wires may lie in parallel. The distance between two neighboring metal cords or wires varies between 0.40 mm and 3.20 mm, e.g. between 0.50 mm and 3.0 mm.
Next to the advantage of an increased stab-resistance, an additional advantage of contacting and bonding the non-woven textile layer to the metal layer is that the non-woven textile layer prevents the wires or cords in the fabric from unraveling when the metal-textile composite is cut to form a stab-resistant insert.
In a first embodiment of the present invention, the metal wires or cords are unidirectional within one single metal layer, i.e. the elongated metal elements do not cross each other. The metal elements are bonded to the non-woven material by means of an adhesive or by means of a thermoplastic film in order to decrease the likelihood of the elongated metal elements shifting towards each other. In this first embodiment, preferably more than one metal layer is provided. In the various metal layers the elongated metal elements have at least two different directions for the elongated metal elements. When a knife happens to have penetrated a first metal layer, the likelihood of being stopped in a second or subsequent metal layer increases if the second or subsequent metal layer have directions different from the direction in the first layer. Similarly, the likelihood of stopping a knife increases if the number of metal layers increases. However, the number of metal layers is limited by reasons of weight and stiffness. Up to six unidirectional metal layers are possible. Two, three and four unidirectional layers are preferable.
In a second embodiment of the present invention, at least one metal layer is multi-directional, e.g. bi-directional. This means that within one single metal layer, the elongated metal elements cross each other. This can be realized by welding or by weaving the warp and weft elongated metal elements. Preferably, the warp and weft elongated elements are woven. Preferably the warp and weft elongated elements make a right angle (90°) with each other. The non-woven material is bonded to the metal layer by means of either an adhesive or by means of a thermoplastic film or by means of stitches. This second embodiment has the drawback of having a metal layer which is somewhat stiffer than a single metal layer out of the first embodiment (unidirectional) but has the advantage that in the final insert, less metal layers are required for a same degree of stab resistance. One or two multi-directional metal layers are preferred. This reduced number of metal layers in the second embodiment may lead to more flexibility or to less weight, compared to the first embodiment.
For both the first and the second embodiment, the inventors have experienced that it is advantageous if the non-woven material comprises some parts, which penetrate between the elongated elements of the metal layer. This penetration may be realized, for example, by needle felting the non-woven material so that the fibers are no longer oriented two-dimensionally alone in the plane of the non-woven material but that some of the fibers are also oriented in a plane perpendicular to the plane of the non-woven material. In this way some of the fibers protrude out of the plane of the non-woven material to penetrate between the elongated elements. This penetration decreases the likelihood that the elongated elements shift towards each other. The presence of the adhesive or of the stitches accentuates this effect.
The non-woven material preferably comprises synthetic fibers. The non-woven material most preferably comprises synthetic fibers which are known to have an impact absorbing effect, such as aramid fibers, para-aramid fibers, high-density high-molecular weight polyethylene fibers, poly(p-phenylene-2,6-benzobisoxazole) fibers (PBO fibers), polybenzimidazole fibers (PBI fibers) or any combination hereof.
In the stab-resistant insert each metal layer may be in contact with and connected with two textile layers, one at each side.
The invention also relates to a protective textile comprising a stab-resistant insert, as described hereabove. The protective textile usually also comprises a bullet-resistant insert. The bullet-resistant insert is normally located close to the body and the stab-resistant insert normally forms the exterior part.BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described into more detail with reference to the accompanying drawings wherein
An insert as stab-resistant element according to this first embodiment of
This second embodiment has proved to be particularly successful as stab-resistant element in combination with a stack of layers of paraaramid or aramid fibers as bullet-resistant element.
The present invention is not limited to a particular type of elongated metal elements. Metal wires and metal yarns are suitable. However, because of flexibility reasons coupled with safety reasons preference is given to metal multi-strand metal cords with relatively thin filaments, i.e. filaments with a diameter ranging from 0.03 mm to 0.25 mm.
Multi-strand metal cords are usually of the m×n-type, where m is the number of strands and n is the number of filaments within one strand. Examples of multi-strand cords are
Other cord types or not excluded. These other cord types may be of following general structure:
- l+m (+n): I core filaments, a layer of m filaments and, possibly a layer of n filaments
- n×1: n filaments twisted together
- m+n: m filaments in parallel, surrounded by n filaments twisted around each other and around the m filaments
- 1×n CC : compact cord with n filaments all twisted with the same twisting step in the same twisting direction.
The invention is neither limited to a particular type of coating on the metal cords in the metal layer. However, in case the stab-resistant insert is used in a protective textile, which needs to be washed or cleaned, preference is also given to metal cords out of stainless steel or to steel cords being covered with a corrosion-resistant coating such as zinc or a zinc aluminum alloy (from 2% to 9% aluminum).
The invention is suitable for all common and available final tensile strengths from 1500 MPa to about 3500 MPa and more
1. A stab-resistant insert for protective textile, said insert comprising
- at least one metal layer of a fabric with metal cords or metal wires;
- at least one textile layer;
- said textile layer being in contact with and being connected to said metal layer;
- characterized in that said textile layer comprises a non-woven material.
2. A stab-resistant insert according to claim 1, said fabric comprising metal cords or metal wires lying in parallel, the distance between said metal cords or metal wires varying between 0.40 mm and 3.2 mm.
3. A stab-resistant insert according to claim 2, wherein said elongated metal elements are unidirectional within said metal layer and wherein said elongated metal elements are bonded to said non-woven material by means of an adhesive or by means of a thermoplastic film.
4. A stab-resistant insert according to claim 3, wherein said insert comprises more than one metal layer.
5. A stab-resistant insert according to claim 4, wherein said more than one metal layers having different directions wherein said elongated metal elements run.
6. A stab-resistant insert according to claim 2 wherein said at least one metal layer is multi-directional.
7. A stab-resistant insert according to claim 6 wherein said non-woven textile material is bonded to said metal layer by means of an adhes or by means of a thermoplastic film or by means of stitches.
8. A stab-resistant insert according to any one of claims 2 claim 2, wherein part of said non-woven material penetrates between the elongated metal elements to decrease the likelihood of shifting the elongated metal elements in said metal layer.
9. A stab-resistant insert according to claim 1, wherein said non-woven material comprises synthetic fibers.
10. A stab-resistant insert according to claim 9, wherein more than thirty per cent of said synthetic fibers is selected from a group consisting of aramid fibers, high-density high-molecular weight polyethylene fibers, poly(p-phenylene-2,6-benzobisoxazole) fibers, polybenzimidazole fibers, combination thereof.
11. A stab-resistant insert according to any one of the preceding claims claim 1, wherein each metal layer is at both sides in contact with and is connected with a textile layer.
12. A protective textile product comprising a stab-resistant insert according to claims 1.
International Classification: F41H 1/02 (20060101);