Patent Application
20050079783
Fire resistant fabrics are used in a variety of products, such as apparel for firemen and electrical workers, military flight suits, and the like. Such fabrics are commonly made from aramid fibers, which are high strength fibers that have inherent flame resistant (“FR”) properties. While performing well in many respects, aramid fibers have several disadvantages. For one, they are very expensive. Secondly, because of the aramid fiber strength, fabrics made from those fibers have a high propensity to pill. As will be readily appreciated by those of ordinary skill in the art, “pilling” is “the tendency of fibers to work loose from a fabric surface and form balled or matted particles of fiber that remain attached to the surface of the fabric.” (Dictionary of Fiber & Textile Technology, p. 113, copyright 1989, Hoechst Celanese.) Pilling is aesthetically undesirable, both from a look and feel standpoint, and is a common reason for garment retirement. Pilling tends to get worse after wearing and laundering of a garment. Therefore, the pilling propensity of the aramid fabrics can lead to an undesirably shortened life cycle for products made from these fabrics.
The present invention achieves aramid fabrics having pilling resistance levels that were not previously achievable on conventional aramid fabrics. The invention involves producing a fabric from specially spun aramid yarns, then treating the fabric with a special chemical lubricant. The resulting fabrics have high degrees of pilling resistance, while maintaining all of the aesthetic and performance features of their conventional counterparts.
In the following detailed description of the invention, specific preferred embodiments of the invention are described to enable a full and complete understanding of the invention. It will be recognized that it is not intended to limit the invention to the particular preferred embodiment described, and although specific terms are employed in describing the invention, such terms are used in a descriptive sense for the purpose of illustration and not for the purpose of limitation.
The fabrics of the invention are desirably manufactured from vortex spun yarns, such as those manufactured by the method developed by the Murata company of Japan, and known as Murata Vortex Spun (“MVS”) yarns. The yarns are selected to be of a size that will enable the achievement of a desired weight of fabric. The weight can be selected for the desired end use, and in the case of apparel, will desirably range from about 2 to about 10 oz/sq yard, or in the case of a flight jacket fabric, will desirably be about 4 to about 5 oz/sq yard, and more preferably, about 4.4 to about 4.6 oz/sq yard.
The yarns are formed into a fabric using a conventional fabric formation method such as weaving. The fabric can be of any construction, including but not limited to a plain weave, twill weave, satin weave, oxford weave, or the like.
The spun yarns are desirably made from a majority of aramid fibers having inherent FR properties, such as those marketed under the tradename Nomex by E. I. duPont de Nemours and Company of Wilmington, Del. However, the yarns may also include some quantity of other fibers, such as other aramid fibers, nylon, FR rayon, etc. For example, one blend that has been found to perform well in the invention is known commercially as Nomex IIIA®, which includes a blend of Nomex® FR aramid fibers, Kevlar® aramid fibers, and P-140 nylon fibers. Preferably, the yarns include at least about 90% of FR aramid fibers.
As noted previously, the fibers are desirably vortex spun. One company identified as having vortex spinning capability is Pharr Yarns of McAdenville, N.C. The fabric is desirably made substantially entirely from the vortex spun yarns.
However, it was found that when fabrics were woven from vortex spun yarns and treated with the conventional chemistry used on the current products (made from ring spun yarns), the strength characteristics were significantly lower than those of the fabrics made from the ring spun yarns (and too low for certain end uses.) However, it was surprisingly found that with the application of a particular lubricant, strength levels and hand levels approximating those of the fabrics made from ring spun yarns could be achieved.
The fabric also desirably contains about 0.25-3% of a high molecular weight ethoxylated polyester lubricant (on weight of fabric.) The lubricant can be added at any point in the manufacturing process. For example, in one method of the invention, the fabric is woven, then prepared (i.e. washed) in a conventional manner, then dried, also in a conventional manner. The fabric is then desirably passed through a chemical bath containing lubricant, and other chemicals as may be desired (e.g. flame retardants, repellents, soil release agents, sewing lubricants, etc.) In this embodiment of the invention, the fabric desirably achieves about 80% initial wet pick up, which is reduced by passage over a vacuum slot to about 35% wet pick up. The fabric is then dried and taken up, and it has about 0.25 to about 3% lubricant on the fabric.
The lubricant is preferably in the form of a high molecular weight ethoxylated polyester; however, other types of lubricants may also be used within the scope of the invention, provided that they achieve the requisite aesthetic and performance characteristics.
A conventional FR aramid fabric of the variety conventionally used to produce military flight suits was produced. Specifically, a fabric was woven in a plain weave construction in a conventional manner, using 39.8/2 ring spun yarns of Nomex IIIA (92% Nomex FR aramid fiber, 5% Kevlar® fiber, and 3% P-140 nylon fiber, commercially available as Nomex IIIA® from E. I. duPont de Nemours and Co. of Wilmington, Del.) in each of the warp and the filling directions. The fibers had been dyed during the fiber manufacturing process. The fabrics were then prepared and dried in a conventional manner, and passed through a chemical bath of 1.0% flame retardant (Antiblaze NT, commercially available from Rhodia, Inc. of Cranbury, N.J.) and 1.0% high density polyethylene emulsion sewing lubricant (Atebin 1062, commercially available from Boehme Filatex of Reidsville, N.C.). Concentrations were based on concentration of bath at about 80% wet pick up, which was reduced to 35% wet pick up via passage over a vacuum slot. The fabric was then dried in a conventional manner and taken up. The fabric had a finished weight of 4.35 oz/sq yard, and 70 ends per inch and 49 picks per inch.
A fabric was woven in a plain weave construction, using 39.8/2 Murata Jet Spun (“MJS”) yarns of Nomex IIIA in the warp and filling directions. The fabric was then prepared and dried in a conventional manner, and passed through a chemical bath containing 1.0% flame retardant (Antiblaze NT) and 1.0% sewing lubricant (Atebin 1062). Concentrations were based on concentration of bath at about 80% wet pick up, which was reduced to 35% wet pick up via passage over a vacuum slot. The fabric was then dried in a conventional manner. The fabric had a finished weight of 4.40 oz/sq yard, and 70 ends per inch and 50 picks per inch.
A fabric was woven in a plain weave construction, using 39.8/2 Murata Vortex Spun (“MVS”) yarns of Nomex IIIA in the warp and filling directions. The fabric was then prepared and dried in a conventional manner, then passed through a chemical bath including the following: 1.0% flame retardant (Antiblaze NT), 1.0% sewing lubricant (Atebin 1062), and 1.0% high molecular weight ethoxylated polyester (Lubril QCX from Tennessee Eastman) at a wet pick up of about 80%, which was reduced to 35% wet pick up via passage over a vacuum slot. The fabric had a finished weight of 4.37 oz/sq yard, and 70 ends per inch and 49 picks per inch.
TEST METHODS
pH—pH was measured according to ASTM D2165-1994.
Fabrics from Examples A and C were then taken following weaving, and treated as follows (percentages in the chemical baths are on weight of bath): A1 and C1 were prepared in a conventional manner and dried. The fabrics were then passed through a chemical bath including the following: 1.0% flame retardant (Antiblaze NT, commercially available from Rhodia, Inc. of Cranbury, N.J. and 1.0% sewing lubricant (Atebin 1062, commercially available from Boehme Filatex of Reidsville, N.C., at a wet pick up of about 80%, which was reduced to a wet pick up of 35% via passage over a vacuum slot. The fabrics were then dried in a conventional manner, and taken up.
A2 and C2 were prepared in a conventional manner and dried. The fabrics were then passed through a chemical bath including the following: 1.0% flame retardant (Antiblaze NT) and 2.0% sewing lubricant (Atebin 1062), at a wet pick up of about 80%, which was reduced to a wet pick up of 35% via passage over a vacuum slot. The fabrics were then dried in a conventional manner and taken up.
A3 and C3 were prepared in a conventional manner and dried. The fabrics were then passed through a chemical bath including the following: 1.0% flame retardant (Antiblaze NT), and 3.0% sewing lubricant (Atebin 1062), at a wet pick up of about 80%, which was reduced to a wet pick up of 35% via passage over a vacuum slot. The fabrics were then dried in a conventional manner and taken up. The fabrics had a high tendency to fray.
A4 and C4 were prepared in a conventional manner and dried. The fabrics were then passed through a chemical bath including the following: 1.0% flame retardant (Antiblaze NT), 1.0% sewing lubricant (Atebin 1062), and 1.0% high molecular weight ethoxylated polyester (Lubril QCX from Tennessee Eastman) at a wet pick up of about 80%, which was reduced to a wet pick up of 35% via passage over a vacuum slot. The fabrics were then dried in a conventional manner and taken up.
The fabrics were tested according to the same methods described above, and the results are listed in the table below.
As illustrated, the fabric of the invention had good FR performance and aesthetic characteristics at a high level of strength. While particularly described in connection with the manufacture of apparel, it is noted that the fabrics can be used in any other end use where FR and fabric strength characteristics are desired and pilling is considered to undesirable, including but not limited to all forms of apparel (shirts, jackets, hats, gloves, pants, shorts, coveralls, etc.), upholstery, etc.
The fabrics of the invention desirably have good FR characteristics, as evidenced by a char length of about 4 inches or less when tested according to Fed. Mtd. 5930 (1978) Test Method, and a pilling of greater than 2 after 90 minutes when tested according to ASTM D3512-2002, and even more preferably about 2.5 or greater, and even more preferably, about 3. In addition, the fabrics desirably having a pilling rating of greater than 3 after 60 minutes, and a pilling rating of greater than 3.5 after 30 minutes.
In the specification there has been set forth a preferred embodiment of the invention, and although specific terms are employed, they are used in a generic and descriptive sense only and not for purpose of limitation, the scope of the invention being defined in the claims.
