| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | December 16, 2003 |
| PATENT TITLE |
Stab resistant material |
| PATENT ABSTRACT | The present invention is a stab-resistant material made from at least two woven fabrics joined using a polymer film. The woven fabrics are made from yarns having a tensile strength of at least 900 MPa. The polymer film joining the woven fabrics has a tensile strength of at least 10 MPa and a flexural modulus of 1500 to 4500 MPa |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | February 5, 2001 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. Stab-resistant material, comprising at least more than one laminate consisting of two woven fabrics laminated together with a polymer film such that the two woven fabrics are joined via the polymer film, wherein the fabrics comp se yarns having a tensile strength of at least 900 MPa, and the polymer film joining the fabrics has a tensile strength of at least 10 MPa and a flexural modulus of 1500 to 4500 MPa. 2. Stab-resistant material according to claim 1, wherein the yarns have a tensile strength of 900 to 8000 MPa. 3. Stab-resistant material according to claim 1, wherein the polymer film has a flexural modulus of 2000 to 3000 MPa. 4. Stab-resistant material according to claim 1, wherein the fabrics have a plain weave. 5. Stab-resistant material according to claim 1, wherein the fabrics have a fabric density, calculated according to Walz, of 25 to 80%. 6. Stab-resistant material according to claim 1, wherein the polymer film is a polycarbonate. 7. Stab-resistant material according to claim 1, wherein the polymer film has an elongation at break of at least 80%. 8. Stab-resistant material according to claim 1, wherein the yarns are aramids. 9. A stab-resistant package comprising a plurality of the laminates of the stab-resistant material according to claim 1. 10. The stab-resistant package according to claim 9, comprising 6 to 30 laminates of the stab-resistant material. 11. The stab-resistant package according to claim 10, comprising 10 to 25 laminates of the stab-resistant material. 12. The stab-resistant package according to claim 10, wherein at least some or all of the laminates are arranged in an envelope made from a textile material. 13. Protective clothing containing the stab-resistant package of claim 12. 14. Protective clothing containing the stab-resistant package of claim 9. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
BACKGROUND OF THE INVENTION 1. Field of Invention The invention relates to a stab-resistant material made from at least two woven fabrics joined by using a polymer film, a stab-resistant package, and use of the stab-resistant package in making protective clothing. 2. Description of Related Art A stab-resistant material is known from WO 97/21334, wherein the polymer film used in the material has a flexural modulus of 42 to 1000 MPa. From the examples of WO 97/21334, it is clear that 38 to 45 layers of the stab-resistant material are required to provide stab protection that the specification considers to be sufficient. The evaluation of the stab-resistant quality in WO 97/21334 is performed in accordance with CEN/TC 162/WG 5 N 479. According to this standard, two different knives are to be used, and the penetration of each knife up to 20 mm is regarded as sufficient stab protection. WO 97/21334 teaches the use of 38 to 45 layers of its stab-resistant material to be sufficiently stab-resistant. The use of 38 to 45 layers of the stab resistant material in WO 97/21334 results in reduced wearing comfort since the large number of layers makes the clothing both very heavy and stiff to the wearer. As described above, there is still a need for stab-resistant material that offers improved wearing comfort and improved effectiveness. SUMMARY OF THE INVENTION It is an aspect of the present invention to provide a stab-resistant material that provides sufficient stab protection. It is a further aspect of the present invention to provide a stab-resistant material to be used in the manufacture of protective clothing that is less heavy and stiff, and offers improved wearing comfort. These and other aspects of the present invention are achieved herein. According to the present invention, a stab-resistant material made from at least two woven fabrics which are joined using a polymer film, wherein the fabrics are made from yarns with a tensile strength of at least 900 MPa and the polymer film joining the fabrics has a tensile strength of at least 10 MPa, exhibits improved effectiveness when the polymer film has a flexural modulus of 1500 to 4500 MPa. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The present invention provides a stab-resistant material made from at least two woven fabrics which are joined using a polymer film, wherein the fabrics are made from yarns with a tensile strength of at least 900 MPa, and the polymer film joining the fabrics has a tensile strength of at least 10 MPa and a flexural modulus of 1500 to 4500 MPa. Surprisingly, it has been discovered that, when using such a polymer film, significantly fewer layers of the stab-resistant material of the present invention are required to provide effective stab protection than in the case of prior art stab-resistant materials. The yarns forming the woven fabrics may have a tensile strength of 1500 to 6000 MPa, most preferably 3000 to 6000 MPa. In the respect, practically all yarns suited for use in ballistic protection, such as yarns made from polyolefin, in particular polyethylene, from polyamide, polyimide, polyester, or poly (p-phenylene-2,6-benzobisoxazole) may be used in the present invention. Yarns made from aramids are especially preferred. It has proven especially favorable for the stab-resistant material of the invention to comprise two woven fabrics laminated using the polymer film. In the stab-resistant material of the invention, it is preferred that the polymer film joining the fabrics have a flexural modulus of 1500 to 4500 MPa, most preferably from 2000 to 3000 MPa. Suitable polymers for the polymer film include, for example, hard PVC, with a flexural modulus of between 3500 and 4000 MPa, or polyurethanes with a flexural modulus of between 4000 and 4500 MPa. Polycarbonates are especially preferred. An especially preferred polycarbonate is marketed under the name LEXAN 103 by GE Plastics. LEXAN 103 has a flexural modulus of 2500 MPa, a tensile strength of 70 MPa, and an elongation at break of 120%. It is also advantageous if the polymer film has an elongation at break of at least 80%, for example 100% or 120%. As is also the case in WO 97/21334, the flexural modulus in the present invention is to be determined in accordance with ASTM D-790, the tensile strength of the film in accordance with ASTM D-638, the elongation at break in accordance with ASTM D-638, and the tensile strength of the yarn in accordance with ASTM D-885. Regarding the fabrics used for the stab-resistant material of the invention, it is preferred that they have a plain weave, especially if they have a fabric density, calculated according to Walz, of 25 to 80%, preferably 25 to 60%. The fabric density according to Walz is calculated according to the following formula: DG=(d.sub.k+ d.sub.s).sup.2.multidot.f.sub.k.multidot.f.sub.s where: d.sub.k =substance diameter of the warp yarn in mm; d.sub.s =substance diameter of the weft yarn in mm; f.sub.k =warp threads per cm; and f.sub.s =weft threads per cm. The substance diameter d.sub.k or d.sub.s of the yarns is calculated as follows: d=(titer).sup.1/2 /88.5 (density).sup.1/2 where d is either d.sub.k or d.sub.s, the titer of the corresponding yarn is in dtex, and the density of the yarn is in g/cm.sup.3. The values given above apply in particular to fabrics with plain weave. If other than plain weaves apply, a weave correction factor must be included in the calculation. For this weave correction factor, the following values are used for fabrics with specific weaves: Weave Weave correction factor Hopsack weaves 2:2 0.56 Twill weaves 2:1 0.70 Twill weaves 2:2 0.56 Twill weaves 3:1 0.56 Twill weaves 4:4 0.38 Satin 1:4 0.49 The fabric density DG calculated according to the Walz formula is multiplied by these correction factors. The fabric density DG according to Walz is a quantity expressed in %. In the case of highly dense fabrics, values can exceed 100%. The stab-resistant material of the invention is optimally suited for manufacturing stab-resistant packages that have multiple layers of the stab-resistant material of the invention. It is especially favorable for a stab-resistant package of the invention to have 6 to 30 and preferably 10 to 25 layers of the stab-resistant material. It is also possible to have additional layers made from other materials. For improved handling, it is advantageous that in the stab-protection package of the invention, several or all layers are positioned in an envelope made from a textile material. The stab-resistant package in accordance with the invention is optimally suited for manufacturing protective clothing |
| PATENT EXAMPLES | Available on request |
| PATENT PHOTOCOPY | Available on request |
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