Structure with breathable fabric for the production of ballistic and stab-resistant protections

Abstract

The present invention relates to a flexible, breathable, anti-penetration fabric, made of antiballistic yarns, partially o wholly impregnated with one or more polymer resins, having a positive coefficient of expansion and hardness greater than 75 Sh D. The structure obtained by the process according to the present invention provides transpiration qualities which make the protections realized with this structure particularly comfortable.

Claims

1. A structure for the production of stab-resistant ballistic protection, the structure comprising: at least one textile element including fibers having a negative axial Coefficient of Thermal Expansion (CTE); and wherein the textile element is impregnated with at least one polymer resin having a positive Coefficient of Thermal Expansion (CTE), hardness greater than 75 Shore D, and a cohesive strength such that, once dry, the polymer resin becomes crumbly.

2. The structure according to claim 1, wherein the at least one polymer resin has hardness greater than 80 Shore D.

3. The structure according to claim 1, wherein the at least one polymer resin comprises at least one resin selected from: natural or synthetic resins rosin type, epoxy, phenolic, polyamide, acrylic, polyurethane, PVC, PVA.

4. The structure according to claim 1, wherein the at least one polymer resin includes a copolymer Butyl Acrylate-Methyl Methacrylate.

5. The structure according to claim 1, wherein the at least one polymer resin includes 5-cloro-2-metil-2H-isotiazol-3-one.

6. The structure according to claim 1, wherein the at least one resin includes 2-metil-2H-isotiazol-3-one.

7. The structure according to claim 6, when depending on claim 5 wherein the components 5-cloro-2-metil-2H-isotiazol-3-one and 2-metil-2H-isotiazol-3-one are mixed together.

8. The structure according to claim 7, wherein the at least one polymer resin includes acrylic resin Acrilem 7105.

9. The structure according to claim 1, wherein the axial CTE of the fibers of the textile element is between 2010.sup.6/ C. and 0/ C.

10. The structure according to claim 1, wherein the CTE of the at least one polymer resin is greater than 1010.sup.6/ C.

11. The structure according to claim 1, wherein the polymer layer once dry has a structure with gaps which let air pass through.

12. The structure according to claim 11, wherein the gaps include micropores having a size between 10 and 300 m.

13. The structure according to claim 1, wherein the at least one polymer resin comprises at least a first and a second resin, mixed with the first resin, the second resin having hardness lower than 75 Shore D, elongation greater than 300% , and wherein the percentage of weight of the second resin does not exceed 10% of the total resin.

14. The structure according to claim 1, wherein particles having a size between 2 and 200 nm are dispersed in the at least one polymer resin.

15. The structure according to claim 14, wherein the particles are composed of at least one of the following materials: TiO.sub.2, Al.sub.20.sub.3, Sic, Si.sub.3N.sub.4, carbon.

16. The structure according to claim 1, wherein the textile element comprises fibers of at least one of the following groups: aramid, co-poliaramid, polyurethane, polybenzo-oxazole, polyethylenes, carbon yarns or glass.

17. A production process for making a structure according to claim 1, the process comprising the following steps: applying at least one polymeric resin in liquid form to the at least one textile element; drying of the polymer resin; pressing the structure, in which the step of pressing is carried out at a temperature T.sub.p such that the following condition is respected:
|CTE.sub.f*(T.sub.pT.sub.a)|+|CTE.sub.r*(T.sub.pT.sub.a)|>30010.sup.6 wherein CTE.sub.f is the (negative) CTE of the fibers of the textile element; T.sub.a is the ambient temperature; CTE.sub.r is the (positive) CTE of the polymer resin.

18. The production process according to claim 17, wherein the temperature T.sub.p is between 20 and 200 C., the pressure is between 5 and 200 bar and the pressing time is longer than 5s.

19. A ballistic protective article comprising a structure according to claim 1.

Description

DETAILED DESCRIPTION

(1) These and further advantages, objects and characteristics of the present invention will be better understood by those skilled in the art from the following description, with reference to the illustrative embodiments having purely illustrative character, and not intended as limiting.

(2) Ballistic yarns with negative axial coefficient of expansion have been used for the production of fabrics resistant to cold weapons and bullets, which are breathable and flexible. The negative coefficient of expansion means that the length of the yarn decreases with the increase of the temperature.

(3) Such yarns useful for the object of the present invention include aramid, co-polyaramid, polyurethane, polybenzo-oxazole, polyethylenes yarns, yarns of carbon or glass. The tenacity of such yarns must be greater than 10 gr/dtex, the modulus greater than 300 Gpa and the elongation to rupture greater than 1%.

(4) The negative axial coefficient of expansion of such yarns, useful for the object of the present invention, must be negative and greater than 2010.sup.6/ C., preferably in the range of 2010.sup.6 to 0, 110.sup.6 per degree centigrade.

(5) The indicated yarns are woven to obtain a stable structure. The characterization of such structures is indicated as weave. Therefore, a number of weaves are known that include plain weaves, double weaves, twills, satins, etc.

(6) Weaves which are particularly useful for the object of the present invention are represented by fabrics having plain weave structure, where each weft thread crosses each warp thread.

(7) The textile structure can also be composed of yarns deriving from different polymers combined together and having a different size (count). In any case, at least 30% of such yarns must have a negative axial coefficient of expansion.

(8) The count of yarns is in the range of 100 to 4500 dtex, preferably of 200 to 3360 dtex.

(9) The weight of the fabrics, before impregnation, is in the range of 80 gr/m.sup.2 to 1000 gr/m.sup.2, preferably 120 to 500 gr/m.sup.2.

(10) The yarn can be pre-treated before the weaving or the fabric can be subjected, before impregnation, to the treatments that activate polarly the surface; this applies especially to fabrics based on fibers of ultra high molecular weight polyethylene, for example greater than 1,000,000. The yarns can be twisted with twisting turns comprised between 10 turns per meter and 200 turns per meter. The used yarns can also have a discontinuous form.

(11) The fabric, before being impregnated with the polymer resin, can be treated with other resins (for example, silicones or fluorocarbons) in order to modify adhesion of the polymer/s, subject of the present invention, to the fibers of the yarns that compose the fabric.

(12) Application of the resin (or resins) to the fabric, according to an embodiment of the present invention, is carried out by technologies which are well known to those skilled in the art, for example, by doctoring, spraying, immersion; if the resin is carried by a solvent, afterwards the solvent is made evaporate completely. If the resin is in powder form, the drying step is not necessary. The fabric can also be partially impregnated or impregnated on only one surface.

(13) Advantageously, after the impregnation step, the fabric is subjected to a pressing step, with the pressure variable from 1 to 200 bar and a temperature, which is selected in such a way as to respect the following relation
|CTE.sub.f(T.sub.pT.sub.a)|+|CTE.sub.r(T.sub.pT.sub.a)|>30010.sup.6
where CTE.sub.f is the (negative) axial coefficient of expansion of the yarn of the textile element

(14) T.sub.p=pressing temperature

(15) T.sub.a=temperature of the surrounding environment, with which the yarn or the resin are balanced

(16) CTE.sub.r is the coefficient of expansion of the resin.

(17) The polymer or the polymers that impregnate the fabrics must have a positive coefficient of expansion greater than 1010.sup.6C. These polymers include, for example, natural or synthetic resins, such as rosin, epoxy, phenolic, polyamide, acrylic, polyurethane resins, PVC, PVA. The hardness of such resins must not be lower than 75 Sh D and the elongations must be smaller than 5%.

(18) In a preferred embodiment, the used resin can relate to a solution of a thermoplastic acrylic polymer of the 7105 type (ACRILEM 7105), produced by Icap Sira, for which it is not possible to realize a structure that can be consolidated by itself due to the fragility of the resin. The capacity of cohesion is null, so that, once dried, the product can be easily reduced to powder only with fingers. ACRILEM 7105 resin contains a copolymer Butyl Acrylate-Methyl methacrylate; more specifically it includes the following components mixed together: 5-cloro-2-metil-2H-isotiazol-3-one [EC no. 247-500-7] and 2-metil-2H-isotiazol-3-one [EC no. 220-239-6].

(19) Another polymer (B) can be added to this polymer (A) in as much as 10% by weight with respect to the resin A, as a modifier of the polymer adhesion to the fibers of the yarns.

(20) The polymers based on elastomeric polyurethane, polybutene, polyisobutene, acrylic, meta acrylic polyvinyl butyral resins, and the like are particularly useful for the purpose of the present invention.

(21) Respecting the above mentioned rules, the polymer resins A or A+B can include ceramic or non ceramic particles, also in the form of nanoparticles, having dimensions in the range of 2 to 200 nm, for example, particles based on TiO.sub.2, Al.sub.2O.sub.3, Sic, Si.sub.3N.sub.4, carbon. These particles can increase the friction value of the blade or bullet, thus improving the performance of the product.

(22) The amounts of such resin/s to be applied are in the range of 10 gr/m.sup.2 to 200 gr/m.sup.2 of dry product on the fabric. In particular, in percentage terms, the amounts of dry resin on the fabric are in the range of 10% to 80% and preferably in the range of 20% to 60%.

(23) The formation of gaps due to the rigidity of the resin and the difference of the absolute coefficient of expansion between the resins and the yarn of the fabric allows to obtain gaps both in the form of small holes and cracked areas. The bigger the difference between the coefficient of expansion of the yarn and the coefficient of expansion of the resin, the bigger such gaps and the higher molding temperature.

(24) The gaps obtained with this process vary from 30 to 300 micron. In particular, the acrylic polymer resin 7105, shows an absolute resistance to the extreme environmental humidity conditions, as it can be deduced from the tests described below: a series of fabrics called Style 640 made of Aramide Kevlar yarns produced by DuPont, weighing 165 gr/m.sup.2 and obtained with fibers of 670 dtex, have been impregnated with about 70 gr/m.sup.2 of the resin 7105. After drying and molding at 125 C., a series of specimens have been subjected to an artificial conditioning at a temperature of 60 C. and relative humidity of 90%.

(25) A sufficient quantity of such fabrics have been taken at intervals of 250 hours. The same fabrics re-conditioned at 20 C. with humidity at 60% have been subjected to the knife action according to the American rule 01 0115NIJ using the blade P1B and awl as indicated. All the tests have been carried out with a new blade for each impact with energy of 50 Joules and with new awls for each impact with energy of 50 Joules.

(26) Samples Typology

(27) The samples have been produced according to OPR87/C/2014.

(28) Style 640 scoured fabric impregnated with resin 65 g/m.sup.2 and molded.

(29) Packages of 30 layers for a weight of about 6.4 kg/m.sup.2

(30) Ageing Process

(31) Ageing in a temperature chamber at 90% U.R. and 60 C. for 250, 500, 750, 1000 hours.

(32) At the end of each ageing period, the samples are dried and conditioned at 20 C. and 60% U.R. for 24 hours.

(33) Test Procedure

(34) Test according to HOSDB, blade P1B.

(35) Each package has been subjected to two series of 3 stabs: the first one at 50 Joule the second one at 36 Joule

(36) Distance between the stabs shots: 60 mm

(37) The blade was changed every 3 stabs.

(38) Results

(39) TABLE-US-00001 Package Perforation 50 Joule - mm Perforation 36 Joule mm 0 hours 11 9 7 1 0 0 0 hours 3 3 3 0 0 0 250 hours 6 6 4 0 0 0 250 hours 11 6 4 0 0 0 500 hours 12 6 5 0 0 0 500 hours 10 6 5 0 0 0 750 hours 4 5 5 0 0 0 750 hours 8 4 3 1 0 0 1000 hours 3 9 8 0 0 0 1000 hours 4 8 6 0 0.5 0.5

(40) For the sake of completeness, the packages aged 0 hours, 750 hours and 1000 hours have been tested with 9 mm Remington.

(41) The results are as follows:

(42) TABLE-US-00002 V50 9 mm Remington 30 layers with foam m/s Package A B 0 hours 408 410 750 hours 378 1000 hours 376 376

(43) For the awl=0.

(44) Consequently, it is to be noted that the stability of the resin is optimal even after 1000 hours of conditioning.

(45) Another series of composed laminated fabrics obtained according to the present invention have been compared with another series of fabrics without resin, so as to verify their wear resistance. The used system complies with regulations UNI EN ISO 12947-1:2000, UNI 12947-3:2000 (Martindale) to verify whether the resin fragility could jeopardize the mechanical characteristics. After 20,000 cycles the fabric in its unaltered state has lost 15.8 mg of its weight, the laminated fabric has lost 15.4 mg of its weight, which is a slightly better result with respect to the fabric in its unaltered state.

(46) Another series of resin-added and laminated fabrics have been then subjected to the air permeability tests according to UNI EN ISO 9237:1997; the applied vacuum is equal to 200 Pa. The result indicates an average permeability of 1.55 mm/s, which confirms that the required targets have been met also in breathability terms.

(47) In another preferred embodiment, 5% of an elastomeric polymer of the Kraton 3301 type (type B Resin) has been added to the resin 7105.

(48) Using the same production process proposed by the present invention, 32 overlaid layers of 40 cm40 cm have been produced. These layers of fabrics of aramid fiber of the DuPont K29 type Kevlar weighing 190 gr/m.sup.2, added with resin with 80 gr/m.sup.2 of resins A+B to check their contemporaneous resistance to knife, bullet and awl according to the regulations NIJ 01 004 Level IIIA and NIJ 01 0115 Level 50 Joules. The regulation requirements have been easily met and the air permeability resulted to be 2.05 mm/s.

(49) It is understood that, within the scope of the present invention, the term polymer refers to a polymeric material, as well as to natural or synthetic resins and their mixtures. It is also understood that the term fiber refers to elongated bodies, whose longitudinal dimension is much longer than the transversal dimension.

(50) In practice, in any case, the implementation details can vary in the same way for what refers to the singular constructive elements, as described and illustrated, as well as to the nature of the indicated materials, without departing from the adopted solution concept and consequently, remaining within the protection provided by the present patent.