Patent Application
20140272361
The invention relates to protective garments, and more particularly, to flexible protective fabrics used in making protective garments.
The variety and types of threats encountered by soldiers in combat, as well as by law enforcement officers and others, continues to expand. Also, it can be difficult to be certain when circumstances are “safe,” and when combat may be imminent.
Soldiers have long worn protective armor to offset many kinds of threats, but such armor typically includes thick, rigid panels and is too bulky, heavy, and inflexible to be worn at all times. Moisture transport can also be quite low for such armor, making the armor uncomfortable to wear. As a result, protection is not always worn when it is needed. In addition, such traditional armor solutions tend to be optimized for only one or two types of threat, while soldiers in the field encounter a wide variety of threats that would be better addressed by a more adaptable fabric armor solution.
Current approaches in protective fabrics typically fall into either of two categories. They are either low cover-factor ballistic and cut fabrics that lack durability and abrasion resistance, and therefore have no capacity to be used as an outer layer, or they are high cover fabrics that are designed for puncture and cut resistance. A good example of this second category is the 28 gauge needle resistance fabrics disclosed by Howland in patent number U.S. Pat. No. 5,565,264. This Howland fabric has a warp cover of 62%, a fill cover of 52%, and combined cover at the crossing points of 114%.
What is needed, therefore, is a new class of protective fabric that combines wearable drape and softness with moisture transport, making the new fabrics comfortable to wear as garment fabrics, while also providing good fragment ballistic protection and good abrasion resistance and durability.
The current invention is a new class of protective fabric that is suitable for making flexible and comfortable protective garment. The invention is based, at least in part, on a realization that when the cover factor of a protective fabric is too high, the yarns will be distorted at the crossing points, and this yarn distortion will increase the stiffness and reduce the bendability of the fabric without significantly increasing its protective properties, at least for many types of threat. This yarn distortion effect was not well understood in the field before the present invention. Accordingly, the fabrics of the present invention have a reduced cover factor that is high enough to provide closed interstices, but is not so high as to cause distortion of the yarns at the crossing points.
In embodiments, the bendability, flexibility, and comfort of the present invention are further improved by using a long-float weave such as a twill or satin. Yet another surprising result of the present invention is that the protection offered by such long-float weaves is not significantly reduced as compared to simple weaves, yet the flexibility and comfort are significantly improved.
The new fabrics of the present invention thereby meet three distinct requirements simultaneously. They have wearable drape, softness, and moisture transport, making them comfortable to wear as garment fabrics. They also provide good fragment ballistic protection. And although they are made from ballistic fiber, they also have good abrasion resistance and durability. This combination of wearability, fragment resistance, and durability is unique to the present invention.
The textile of the present invention is woven from yarns comprising at least 20% ballistic fibers having tenacity greater than 12 gpd. At least some of the yarns have a denier greater than 199. Embodiments have a long-float weave pattern with a correspondingly reduced crossing point density, such as a twill or satin weave, so as to improve drape and wearability, and a combined cover factor between 55% and 80% so as to provide vanishingly small interstices without packing or distorting the yarns. As explained in more detail below, we have found it helpful to characterize protective fabrics according to a metric we call the “SCCF×CCD” that is the product of the simple combined cover factor and the crossing point density. The SCCF×CCD for the present invention is less than 100%, and in embodiments is between 10% and 40%. The use of ballistic fibers with high cover factor provides good fragment protection, while the long-float weave pattern provides good drape and flexibility.
The combination of performance features provided by the present invention was a surprising result, because the generally accepted wisdom in the art at the time of the invention was that fabrics made from ballistic fiber were known to have poor abrasion and durability in outer layer applications. Moreover, such protective fabrics hand, and were not used for garments, especially not for garments that made contact with a user's skin. Flying in the face of this generally accepted wisdom, the present invention combines ballistic fibers with a mid-range cover density, and in embodiments also with a long-float weave pattern such as twill or satin, to provide a textile that is both wearable and durable, while also providing a fragment V50 performance to weight ratio that is similar to fabrics designed only for their fragment resistance.
The success of twill, satin, and other long float weaves in the present invention was also surprising. As expected, the long floats in these weaves improve the hand and drape of the fabric. However, it was surprising that the long floats did not have a negative impact on abrasion or fragment performance of the fabrics. The combination of long floats, high strength yarns, and staple yarns mixed with filaments at the right mid-cover factor provides a family of unique and novel fabrics.
The density of crossing points in a weave affects many characteristics of the fabric, including stiffness, abrasion, and cut resistance. Accordingly, the simple combined cover factor can only be used to compare fabrics that have the same crossing point density. However, in some embodiments the mid-cover fabrics of the present invention make significant use of long weave floats instead of plain weaves. In order to compare effective cover factors for different weave types, we have found it useful to use a metric whereby the crossing point density for a long-float weave, divided by the crossing point density of a plain weave, is multiplied times the simple combined cover factor. As discussed below in more detail with reference to
In embodiments, according to circular bending tests and garment tests, the product (SCCF×CPD) of the simple combined cover factor (“SCCF”) and the crossing point density (“CPD”), expressed as a percentage of a simple weave fabric, is less than 100% for mid-cover fabrics in the lower fabric mass range. For similar embodiments in the center range of mass, the SCCF×CPD is less than 40%, even when the SCCF is well about 80%. This is accomplished by reducing the CPD to 50% or less in these fabrics.
In some embodiments a long-float weave pattern such as a twill or satin is utilized both to reduce the crossing point density and thereby improve the hand of the fabric, and also so that the fabric will have a different character on each face. When staple yarns are used in one yarn direction and filament yarns are used in the other yarn direction a floated weave pattern will result in a predominantly staple fabric face and a predominantly filament fabric face. The ratio of crossing points to the plain weave crossing point density is also a measure of the differentiation of the two sides of the fabric. In some embodiments good staple-filament differentiation is found at crossing point densities of less than 50% of a plain weave. Protective garments constructed such that the predominantly staple fabric face is in contact with skin of a user will thereby provide better wearing comfort than similar garments having a plain weave.
One general aspect of the present invention is a protective fabric that includes a fabric woven from yarns, each of the yarns including at least one fiber, at least 20% of the fibers being protective fibers having tenacities greater than 12 gpd, the fabric having a simple combined cover factor of between 55% and 80%, and a product of the simple combined cover factor and a normalized crossing point density of the protective fabric, referred to herein as the “SCCF×CPD,” being less than 100%, where the normalized crossing point density is a ratio of a crossing point density of the protective fabric divided by a crossing point density of a plain weave fabric woven with a yarn denier and simple cover factor equal to those of the protective fabric.
In embodiments, a first cover factor in a first yarn direction is greater than 50% and a second cover factor in a second yarn direction is greater than 30%. In some embodiments the fabric has a V50 for 2 gr RCC fragment of greater than 350 fps for a single ply, as measured using Mil Std test method 662F. In other embodiments at least some of the yarns have a denier greater than 199.
In various embodiments the SCCF×CPD is between 10% and 40%. In certain embodiments, the fabric is woven with a twill or satin weave.
In embodiments, the protective fibers include at least one of para-aramid and liquid crystal polyester (“LCP”) fibers. Some embodiments further include a primer coating greater than 3% by weight, the primer covering substantially all surfaces of all fibers in the fabric.
In various embodiments, the coating provides at least one of UV protection, abrasion protection, and color acceptance. And in certain embodiments the Frazier ASTM permeability of the protective fabric is between 5 and 60 cfm/ft2.
Another general aspect of the present invention is a protective fabric that includes a fabric woven from yarns, each of the yarns including at least one fiber, the fabric having a predominantly staple fiber face and a predominantly filament fiber face, the fabric having a normalized crossing point density of greater than 65%, the fabric having a fabric mass between 95 g/yd2 and 450 oz/yd2, and at least 20% of the fiber being protective fiber with greater than 12 gpd tenacity.
In embodiments, at least some of the yarns have a denier of great then 140. In some embodiments the permeability of the fabric as measured using a Frazier differential-pressure air permeability tester is less than 60 cfm/ft2.
In various embodiments, the fabric has a V50 for 2 gr RCC fragment of greater than 350 fps for a single ply, as measured using Mil Std test method 662F. In certain embodiments, the fabric is woven with a twill or satin weave.
In some embodiments, the protective fibers include at least one of para-aramid and liquid crystal polyester (“LCP”) fibers. Other embodiments further include a primer coating greater than 3% by weight, the primer covering substantially all surfaces of all fibers in the fabric.
In embodiments, the coating provides at least one of UV protection, abrasion protection, and color acceptance. And in some embodiments the Frazier ASTM permeability of the protective fabric is less than 60 cfm/ft2.
Still another general aspect of the present invention is a protective fabric that includes a fabric woven from yarns, each of the yarns including at least one fiber, the fabric having a circular bend of between one and ten lbs, at least 20% of the fibers being greater than 12 gpd, and the fabric having a fabric mass greater than 95 g/yd2.
In embodiments, the fabric has a textile construction having less than 90% of available crossing points. In some embodiments the fabric has a permeability of less than 60 cfm/ft2, as measured using a Frazier differential-pressure air permeability tester. In other embodiments the fabric has a Ref of less than 15 units, as measured according to ASTM standards using a sweating guarded hotplate.
In various embodiments the fabric has a V50 for 2 gr RCC fragment of greater than 350 fps for a single ply as measured using Mil Std test method 662F. In certain embodiments the fabric is woven with a twill or satin weave.
In embodiments, the protective fibers include at least one of para-aramid and liquid crystal polyester (“LCP”) fibers. Some embodiments further include a primer coating greater than 3% by weight, the primer covering substantially all surfaces of all fibers in the fabric.
In other embodiments, the coating provides at least one of UV protection, abrasion protection, and color acceptance. And in various embodiments the Frazier ASTM permeability of the protective fabric is less than 30 cfm/ft2.
Still another general aspect of the present invention is a protective fabric that includes a fabric woven from yarns, each of the yarns including at least one fiber, the fabric having abrasion resistance greater than 5,000 cycles against 400 grit using Martindale abrasion method, at least 20% of the fiber having a tenacity greater than 12 gpd, and the fabric having a fabric mass between 95 g/yd2 and 450 oz/yd.
Embodiments further include a protective coating that is greater than 3% by weight. In some embodiments, the Tensile Property loss of the fabric after 25 AATCC standard washings is less than 10%. In other embodiments the fabric has a UV exposure tensile loss of less than 15% when exposed to AATCC.
In certain embodiments, the fabric has an ASTM vertical flame consumption of less than 50%. In various embodiments the fabric has an EN388/ANSI 150 puncture greater than 3.
In embodiments, the fabric has a V50 for 2 gr RCC fragment of greater than 350 fps for a single ply as measured using Mil Std test method 662F. In some embodiments, the fabric is woven with a twill or satin weave. In various embodiments, the protective fibers include at least one of para-aramid and liquid crystal polyester (“LCP”) fibers.
Certain embodiments further include a primer coating greater than 3% by weight, the primer covering substantially all surfaces of all fibers in the fabric. In some embodiments, the coating provides at least one of UV protection, abrasion protection, and color acceptance. And in some embodiments the Frazier ASTM permeability of the protective fabric is less than 30 cfm/ft2.
The features and advantages described herein are not all-inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and not to limit the scope of the inventive subject matter.
In embodiments, the yarns required to produce the present mid-cover invention are 70 denier (70/1 cc) or larger. From a yarn production perspective, the lower limit on para-aramid yarns is 70 denier in the form of 70/2 cc. For abrasion durability and protection, either filament yarns or 2-ply staple yarns are preferred.
The Cover Factor used to define the present invention is based on calculation of the yarn diameter based on the denier, the specific gravity, and the assumption that the diameter of a round cross section monofilament will remain constant regardless of the number of filaments in a multi filament yarn. This simplifying monofilament treatment avoids any assumptions about multifilament yarn bundle cross section shape. All warp and fill yarn cover calculations use this same calculation of diameter.
The protective fabrics of the present invention can be described as having mid-range cover factors. There are full cover fabrics in the prior art that have maximum practical cover factors, such as in the Howland '264 patent. The mid-cover fabrics of the present invention have a range of cover factors from 25 to 65% in each yarn direction, so that the simple combined cover in both yarn directions is greater than 80%. The simple combined cover factor is the sum of the monofilament cover factors in each of the 2 yarn directions. For production efficiency, the warp direction typically has the higher cover factor, with embodiments exceeding 50% warp cover, and some embodiments exceeding 60%. These higher cover factors are facilitated in various embodiments by using weave designs that float yarns and reduce the number of crossing points. Twills and satin weaves are typical examples of this type of float yarn construction.
On the other hand, because the novelty of the present invention lies in a combination of protection, softness, and durability, the simple cover factor must be limited if there are no floats in the weave. As the cover factor is increased, the packing of the yarns must increase. Eventually, the yarns will become over-packed, especially at the crossing points, and will distort. This is illustrated in
As can be seen in
The density of crossing points in a weave affects many characteristics of the fabric, including stiffness, abrasion, and cut resistance. Accordingly, the simple combined cover factor can only be used to compare fabrics that have the same crossing point density. In embodiments, the mid-cover fabrics of the present invention make significant use of long weave floats, and some embodiments are not plain weaves. In order to compare effective cover factors for different weave types, we have found it useful to use a metric referred to as the “SCCF×CPD,” whereby the crossing point density (CPD) for a long-float weave, divided by the crossing point density of a plain weave, is multiplied times the simple combined cover factor (SCCF). With reference to
In embodiments, according to circular bending tests and garment tests, the product of the simple combined cover factor (“SCCF”) and the crossing point density (“CPD”) expressed as a percentage of a simple weave fabric (“SCCF×CPD”), is less than 100% for mid-cover fabrics in the lower fabric mass range. For similar embodiments in the center range of mass, the SCCF×CPD is less than 40%, even when the SCCF is well about 80%. This is accomplished by reducing the CPD to 50% or less in these fabrics.
The balance of performance required for mid-cover fabrics includes the need for softness. Full Cover fabrics provide sufficient abrasion resistance and protection, but they are not flexible or soft enough for many garment applications. The mid-cover fabrics of the present invention are characterized by a “soft hand,” both by subjective evaluation and per AATCC Procedure #5 Fabric Hand: Guidelines for the Evaluation and objective evaluation per ASTM D4032-08(2012) Standard Test Method for Stiffness of Fabric by the Circular Bend Procedure.
Representative circular bend results are:
T9-1396 Pant twill 2.24 lbf
T9-1424 SPS twill 3.7 lbf
T9-1400 Jacket 5.25 lbf
All of these results represent acceptable fabric softness for garment applications. Embodiments of the present invention run at the high end of the range of circular bending, as a result of the compromise in the need for penetration performance and abrasion resistance.
High cover fabrics have protective and durability but lack the softness of mid-cover fabrics. Low-cover fabrics lack the durability of mid-cover fabrics in demanding outer wear garment applications.
Some embodiments of the present invention include Para Aramid fibers, while other embodiments include other fiber types according to the requirements of the application. Blending Para Aramid is also effective in applications. In embodiments, Para Aramid or another protective fiber may have insufficient resistance to chemical, abrasive or UV degradation, or to a combination of these factors. In some of these embodiments a coating is applied to the fiber to improve its resistance to such attacks. The type of protection that is required defines the coating type. In many embodiments, acrylic, urethane, neoprene, nitrile, or silicone emulsions or solvent solutions are used. These coating resins can produce soft, thin deposits that have very limited impact on the stiffness of the fabric. These resins can be modified with fillers and additives as required to improve the resistance of the fabric to attack. A typical add-on for a resin-filler system is 0.5-2.5% of the fabric weight.
With reference to
Following are abrasion behavior Martindale results for durability in embodiments of the present invention:
T9-1396 Pant twill 6042 cycles on 400 grit
T9-1424 SPS twill 9000 cycles on 400 grit
T9-1400 Jacket 7181 cycles on 400 grit
All these results represent good durability results and will support long wearing and good garment life.
Following are Perm -Ref range results for embodiments of the present invention, which has a direct effect on the comfort of the fabrics
T9-1396 Pant twill 5.12 REF (Pa*m2/W)
T9-1398 oxford 3.59 REF (Pa*m2/W)
T9-1400 Jacket 5.68 REF (Pa*m2/W)
The resistance of a fabric to moisture vapor transmission at 35 C skin temperature is a very sensitive measure of the textile's ability to support evaporative cooling at the skin of a user in hot weather. The values of REF in the 3 to 6 range for the present invention are typical of the REF values of conventional uniform and work garment fabrics, and support comfortable wear even in a hot climate.
Note that the following test methods are included by reference:
1 Circular bending
2 Fabric mass
3 End count
4 Martindale Abrasion
5 Fiber tenacity
6 Textile tensile
7 Vertical flame
8 Cut testing 1790
1 Solar exposure
2 Standard wash test
3 Procedure #5 subjective determination of fabric hand
EN388 puncture
Ballistic testing 662f
The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of this disclosure. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.
This application claims the benefit of U.S. Provisional Application No. 61/779,250, filed Mar. 13, 2013, which is herein incorporated by reference in its entirety for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 61779250 | Mar 2013 | US |
