Patent Application
20170058435
The present application relates to composite yarns used in textiles and fabrics.
Textiles have evolved drastically for uses in various applications, in which the textiles have technical features enabling them to perform different protective functions. For instance, textiles may be fire resistant, may protect against electric arc, may be waterproof yet breathable, may be puncture proof or rip proof, among numerous other possible characteristics. Oftentimes, the textiles gain their characteristics from the yarns or fibers that constitute them.
The challenge remains to offer textiles with such protective features, while preserving other characteristics. For example, garments made with textiles having such protective features must remain as lightweight and flexible as possible and thus not hamper free movements of the wearer. Other characteristics apply to other applications as well. On the other hand, the cost must also be factored in as an important design factor in the choice of a yarn for protective textile.
It is therefore an aim of the present invention to provide composite yarn having a glass core.
Therefore, in accordance with the present application, there is provided a composite yarn comprising: a glass core having a linear weight ranging between 50 to 400 deniers and composing from 15 to 60% of a total linear weight of the composite yarn; and a sheath surrounding the glass core, the sheath constituted at least of fibers of meta-aramid, the sheath constituting a remainder of the total linear weight of the composite yarn; wherein the composite yarn has a yarn count between 10 tex and 80 tex.
Referring to
The glass core 12 serves as the structure or backbone of the composite yarn 10. The glass core 12, by its inherent properties, provides electrical arc protection, and cut protection.
The sheath 14 covers the glass core 12, and serves a different function than the glass core 12. In the embodiment described below, the sheath 14 may be used for its flash fire resistance, and to provide the visual characteristics to the composite yarn 10, for instance by being colored.
According to an embodiment, in order to provide suitable electrical arc protection and tear resistance, the glass core 12 is made of glass fiber filament of approximately 2.50 g/cm3 density±0.45 g/cm3, with a linear weight ranging between 50-400 deniers, such as E-glass (e.g., low alkali alumino-borosilicate glass). The table below provides examples of contemplated linear weight for the glass core 12, along with yarn count minimum for the composite yarn 10:
The glass fiber filament as selected from the parameters of the table will act as an electrical insulator within the composite yarn 10. The linear weight ratio of the glass core 12 in the composite yarn 10 is between 15%-60%, relative to the sheath 14. This linear weight ratio is selected to preserve the fabric integrity if a textile composed of the composite yarn 10 is submitted to flames during a flash fire and/or electrical arc discharge. The proportion of 60% maximum for the core filament is to allow enough staple fibers in the sheath 14 to cover the glass filament of the core 12 inside for comfort and to preserve the color shade of the fabric if applicable. The glass fiber filament of the glass core 12 will help holding the blend of fibers of the sheath 14 within the textile once the textile is exposed to flames, due to its higher softening point, as detailed below.
The sheath 14 is constituted of meta-aramid, and may also incorporate additional different types of fibers, such as para-aramid and/or modacrylic, among other possibilities, which possibilities also include viscose (e.g., FR grade), lyocell, etc, in addition to the meta-aramid. The constitution of the sheath 14 depends on the desired properties of the composite yarn 10.
The sheath 14 spun around the glass core 12 may contain between 35% to 100% meta-aramid fibers, with or without para-aramid fibers or blend of any ratio of meta-aramid/para-aramid. The proportion of meta-aramid and glass content combined must be above 45% of the total linear weight of the yarn to provide sufficient flame resistance to the fabric. Therefore, in a yarn with the lowest proportion of glass core, i.e. 15% and the wrapping 14 of a blend of staple fiber containing 35% meta-aramid, by calculation, a combined proportion of glass and meta-aramid of approximately 45% (44.75%), i.e., above 44%. Any other combination will provide a higher proportion of the combination of meta-aramid and glass. The meta-aramid (e.g., Nomex®, Conex®) is used for its thermal resistance and chemical resistance. If used, the para-aramid (e.g., Kevlar®, Twaron®) would increase the tensile strength of the sheath 14. Both the para-aramid fibers and meta-aramid fibers could be greige (dyeable) fibers or dope dyed fibers. It is also considered to use bale dyed fiber, solution dyed fibers, dope dying before extrusion, or greige fibers.
According to an embodiment, modacrylic fibers or other dyeable fibers such as FR viscose and lyocell are added to the sheath 14 and provided at the surface of the composite yarn 10, so as to allow the dyeing of the yarn 10, for example in a high visibility color. The modacrylic fiber has good dyeing capability, but may start to degrade quicker than aramid. However, the presence of glass filament as the glass core 12 compensates for the lower strength of the modacrylic fiber, such that the presence of modacrylic may have little or no effect on the fabric integrity when constructed as in
For example, by combining a given proportion of modacrylic fiber to the meta-aramid fibers in the sheath 14 of the composite yarn 10, high-visibility color may be attained while preserving fire resistance, which color cannot be obtained with regular yarn made of aramid or aramid/modacrylic that will withstand similar performance in a flash fire/electrical arc discharge. The dyeing could be done in yarn form or in fabric form. Both methods may work with the composite yarn 10.
As yet other possibilities, the mix of fibers of the sheath 14 around the glass core 12 may contain between 0% to 10% antistatic fiber, such as carbon in a polyester or nylon matrix (e.g., Beltron®).
The presence of the glass core 12, with its softening point generally above 700 Celsius (1292 Fahrenheit) remains its integrity when fibers of the sheath 14 may start softening. Moreover, if E-glass type filament is used as glass core 12, the softening point may be at approximately at 846 Celsius (1555 Fahrenheit) For example, a blend of aramid fibers starts decomposing between 427-482 Celsius (800-900 F), while modacrylic fibers start decomposing at 250 Celsius (482 F). Accordingly, the glass core 12 holds up the integrity of a textile of the composite yarn 10 and may therefore protect the wearer for a longer time than fire-resistant fabrics made mostly of aramid fibers.
The yarn count for the composite yarn 10 constituted of the glass core 12 and sheath 14 as described above may be between 10 tex and 80 tex. The composite yarn 10 could be plied in normal twisting textile processing to create coarser and stronger yarns counts, as desired. It is to be noted that the splicing of two ends of core glass yarn could be problematic and could result in a weak spot. Hence, the sheath 14 around the core 12 will strengthen the splice of glass core 12. The yarn integrity will also have to be monitored so that the sheath 14 of staple fiber becomes intermingled with the glass core 12 to avoid any undesirable slip of the sheath 14 over the glass core 12. This may result in an undesired exposure of the glass core 12.
An example of a composite yarn 10 composition of the type that can be dyed is provided below, for a 26.8 Ne yarn count/2 ply composite yarn 10, or for a 13.4 Ne yarn count/1 ply composite yarn 10. The sheath 14 is constituted of 56.3% meta-aramid, 3.7% para-aramid, and 15% modacrylic with orange dye, while the 50 deniers glass core 12 represents 25% of composite yarn 10.
Further examples are provided below, to illustrate the proportion of the constituents of the composite yarn 10 for different yarn counts. It is possible to select the constituents of the composite yarn 10 so that certain characteristics of the textile or fabric would be enhanced, based on the contemplated use of the garment featuring the textile. For example, to increase the cut-resistance of the fabric, the mass of glass in the core 12 may be increased. For example, the composite yarn 10 may include a 100 deniers glass filament instead of a 50 deniers glass filament, effectively doubling the linear weight of the glass in the fabric. As a result, the increased liner weight of glass may improve the cut-resistance performance of a fabric with such glass filament. In a similar fashion, the ratio of constituents of the composite yarn 10 could be adjust to improve the electrical arc performance, as an example. The electrical arm performance may be improved by increasing the linear weight of glass into the yarn 10, and/or adding to the sheath 14 a portion of modacrylic fiber. If the time required for the textile of composite yarn 10 to self-extinguish is critical, a blend could be selected to increase the level of meta-aramid in the sheath 14. Hence, the proportion of constituents of the composite yarn 10 may be chosen to hit specific performance standards, or to optimize the performance of the garment depending the contemplated use or need.
The present application claims the priority of U.S. Patent Application No. 62/211,133, filed on Aug. 28, 2015 and incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62211133 | Aug 2015 | US |
