US20050272340A1

US20050272340A1 - Filamentary blanket

Info

Publication number: US20050272340A1
Application number: US11/137,118
Authority: US
Inventors: Cliff Bridges; Sergio de Leon; Nick Carter
Original assignee: Polymer Group Inc
Current assignee: PGI Polymer Inc; Avintiv Specialty Materials Inc
Priority date: 2004-05-26
Filing date: 2005-05-25
Publication date: 2005-12-08
Also published as: EP1751337A2; MXPA06013641A; WO2005118933A3; WO2005118933A2; EP1751337A4

Abstract

The present invention is directed to continuous filament nonwoven fabrics, and more specifically directed to continuous filament nonwoven fabrics for use as low-cost disposable airline and rescue operation blankets. Continuous filament fabrics are formed utilizing the spunbond process. The spunbond process and the manner of preparing a spunbond web is set forth in U.S. Pat. No. 3,341,394 to Kinney and U.S. Pat. No. 4,043,201 to Brock, et al., both of which are herein incorporated by reference. The filamentary blankets of the present invention may be disposed after a single use or semi-reusable, wherein the blanket has a limited number of uses before needing to be replaced. Such blankets are suitable for a variety of applications, such as insulative blankets, emergency rescue blankets, institutional blankets, airline blankets, and other applications where blankets are used only a limited number of times or in some cases only once before being discarded.

Description

TECHNICAL FIELD

The present invention is generally related to continuous filament nonwoven fabrics, and more specifically related to continuous filament nonwoven fabrics for use as low-cost disposable airline and rescue operation blankets.

BACKGROUND OF THE INVENTION

Nonwoven fabrics are used in a wide variety of applications where the engineered qualities of the fabrics can be advantageously employed. The use of selected thermoplastic polymers in the construction of the filamentary components, selected treatment of the components (either while in molten form or in an integrated structure), and selected use of various mechanisms by which the filamentary components are integrated into a useful fabric, are typical variables by which to adjust and alter the performance of the resultant nonwoven fabric.
Nonwoven blankets are known in the art. Typically, the nonwoven blankets comprise one or more lofty fibrous batts of carded and cross-lapped staple length fiber that is subsequently bonded by needle-felting or entangling. Preferably, one or more post treatments are performed on the consolidated batt, such as jet dyeing and napping in order to lend to the aesthetic appeal of the blanket or enhance the hand of the blanket.
Such a multi-step fabrication process for blankets can be rather costly, and it is therefore an objective of the present invention to manufacture an inexpensive nonwoven blanket for airlines and rescue operations by utilizing the spunbond process. The term “spunbonding” refers to a process in which a thermoplastic polymer is provided in a raw or pellet form and is melted and extruded or “spun” through a large number of small orifices to produce a bundle of continuous or essentially endless filaments. These filaments are cooled and drawn or attenuated and are deposited as a loose web onto a moving conveyor. The filaments are then partially bonded, typically by passing the web between a pair of heated rolls, with at least one of the rolls having a raised pattern to provide a bonding pattern in the fabric. Of the various processes employed to produce nonwovens, spunbonding is the most efficient, since the final fabric is made directly from the raw material on a single production line.

SUMMARY OF THE INVENTION

The present invention is directed to continuous filament nonwoven fabrics, and more specifically directed to continuous filament nonwoven fabrics for use as low-cost disposable airline and rescue operation blankets. Continuous filament fabrics are formed utilizing the spunbond process. The spunbond process and the manner of preparing a spunbond web is set forth in U.S. Pat. No. 3,341,394 to Kinney and U.S. Pat. No. 4,043,201 to Brock, et al., both of which are herein incorporated by reference.
Nonwoven blankets made in accordance with the present invention comprise one or more continuous filament webs of thermoplastic polymers that may be chosen from the group consisting of polyolefins, polyamides, and polyesters, wherein the polyolefins are chosen from the group consisting of polypropylene, polyethylene, and combinations thereof. It is within the purview of the present invention that the continuous filament web or webs may comprise either the same or different thermoplastic polymers. Further, the continuous filaments may comprise homogeneous, bi-component, and/or multi-component profiles, as well as, performance modifying additives, and the blends thereof.
The filamentary blankets of the present invention may be disposed after a single use or semi-reusable, wherein the blanket has a limited number of uses before needing to be replaced. Such blankets are suitable for a variety of applications, such as insulative blankets, emergency rescue blankets, institutional blankets, airline blankets, and other applications where blankets are used only a limited number of times or in some cases only once before being discarded.
Other features and advantages of the present invention will become readily apparent from the following detailed description, and the appended claims.

DETAILED DESCRIPTION

While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment of the invention, with the understanding that the present disclosure is to be considered as an exemplification of the invention, and is not intended to limit the invention to the specific embodiment illustrated.
A spunbond process involves supplying a molten polymer, which is then extruded under pressure through a large number of orifices in a plate known as a spinneret or die. The resulting continuous filaments are quenched and drawn by any of a number of methods, such as slot draw systems, attenuator guns, or Godet rolls. The continuous filaments are collected as a loose web upon a moving foraminous surface, such as a wire mesh conveyor belt. When more than one spinneret is used in line for the purpose of forming a multi-layered fabric, the subsequent web is collected upon the uppermost surface of the previously formed web. The web is then at least temporarily consolidated, usually by means involving heat and pressure, such as by thermal point bonding. Using this bonding means, the web or layers of webs are passed between two hot metal rolls, one of which has an embossed pattern to impart and achieve the desired degree of point bonding, usually on the order of 10 to 40 percent of the overall surface area being so bonded.
The thermoplastic polymers of the continuous filament spunbond layer or layers are chosen from the group consisting of polyolefins, polyesters, polyamides, and halopolymers, with ethylene-fluorocarbon copolymers, particularly ethylene-chlorotrifluoroethylene (ECTFE), wherein the polyolefins are chosen from the group consisting of polypropylene, polyethylene, and combinations thereof. It is within the purview of the present invention that the continuous filament web or webs may comprise either the same or different thermoplastic polymers. Further, the continuous filaments may comprise homogeneous, bi-component, and/or multi-component profiles, as well as, performance modifying additives, and the blends thereof.
Additionally the continuous filamentary web may comprise one or more discontinuous filament webs through application of the meltblown process. The melt-blown process is a related means to the spunbond process for forming a layer of a nonwoven fabric, wherein, a molten polymer is extruded under pressure through orifices in a spinneret or die. High velocity air impinges upon and entrains the filaments as they exit the die. The energy of this step is such that the formed filaments are greatly reduced in diameter and are fractured so that microfibers of finite length are produced. This differs from the spunbond process whereby the continuity of the filaments is preserved. The process to form either a single layer or a multiple-layer fabric is continuous, that is, the process steps are uninterrupted from extrusion of the filaments to form the first and subsequent layers through consolidation of the layers to form a composite fabric. It is also within the purview of the present invention to further include, juxtaposed to the melt-blown barrier layer, additional layers selected from the group consisting of nonwoven, fabrics, woven fabrics, films and combinations thereof.
Nano-denier filaments may be incorporated as well. Suitable nano-denier continuous filament layers can be formed by either direct spinning of nano-denier filaments or by formation of a multi-component filament that is divided into nano-denier filaments prior to deposition on a substrate layer. U.S. Pat. Nos. 5,678,379 and 6,114,017, both incorporated herein by reference, exemplify direct spinning processes practicable in support of the present invention. U.S. Pat. Nos. 5,678,379 and 6,114,017, both incorporated herein by reference, exemplify direct spinning processes practicable in support of the present invention.
Prior to extrusion, the molten polymer can be compounded with various performance enhancing melt-additives, such as thermal stabilizers, softening agents, antimicrobial agents, fire-retarding agents, cross-linking agents, slip additives, and wetting agents, UV, anti-stats, colorants, and nucleating agents. A nucleating agent may be specifically compounded to produce a more stable spinning process, and, at equal process conditions, can produce a further increase in strength. The fabric may be exposed to further performance enhancing additives after fabric formation.
Depending on the blanket end-use application, it may be desirable to have a blanket that exhibits a high degree of strength. It has been contemplated that utilizing polymeric resins with low melt indexes, such as between about 5-20 MI, may enhance the strength of the blanket; however, it is also suitable to utilize polymeric resins with higher melt indexes, about 20-35 MI, depending on the application.
According to the present invention, filaments with varying geometric cross-sections may be utilized, as disclosed in U.S. Pat. No. 5,057,368 to Largman, et al.; U.S. Pat. No. 5,322,736 Boyle, et al.; and U.S. Pat. No. 5,834,119 to Roop. Multi-component filaments may also be utilized as well, such as side-by-side filaments, sheath-core filaments, and islands in the sea filaments. Splittable fibers are also suitable for use in the present invention, wherein upon impact the components of such fibers separate. The aforementioned filaments may be used in whole or in part within one or more layers of the continuous filament blanket.
In one embodiment, the nonwoven blanket of the present invention is comprised of extruded and thermally bonded continuous polyethylene filaments. The resultant blanket has excellent drapeability and hand with a preferred basis weight of about 50-200 grams per square meter and a most preferred basis weight of about 85-130 grams per square meter. Prior to extrusion of the filaments, a pigment was added to the polymeric melt to impart a color into the blanket. Further, subsequent to thermal bonding, the blanket fabric was subjected to a napping post treatment so as to produce a low cost blanket that has the desired insulative, tactile, and visual properties often sought in a blanket.
Optionally, the continuous filament blanket may be hydroentangled on an imaged forming surface, wherein such surfaces include three-dimensionally surfaced belt, metal drums, wire screens, and three-dimensional image transfer devices. Such surface treatments enhance the aesthetic appearance of the blanket, as well as improve the overall bulk and hand of the blanket. Additional surface treatments that may be utilized include mechanical compaction as practiced in micrexing or sanforizing (“Sanforized” is a registered trademark of Cluett, Peabody & Co., Inc).
The filamentary blankets of the present invention are low-cost and suitable for disposed after a single use. Alternately, the blankets may be considered semi-reusable, wherein the blanket may be used a limited number of times before needing to be replaced. Such blankets may be used as insulative blankets, emergency rescue blankets, institutional blankets, airline blankets, as well as in other applications where blankets of limited use are required or in cases where blankets are used once before being discarded.
From the foregoing, it will be observed that numerous modifications and variations can be affected without departing from the true spirit and scope of the novel concept of the present invention. It is to be understood that no limitation with respect to the specific embodiments illustrated herein is intended or should be inferred. The disclosure is intended to cover, by the appended claims, all such modifications as fall within the scope of the claims.

Claims

1. A three-dimensionally imaged disposable blanket comprising one or more layers of thermoplastic continuous filaments and one or more melt additives, wherein said blanket has a basis weight of about 60-200 grams per square meter.

2. A three-dimensionally imaged disposable blanket as in claim 1, wherein said image is imparted by a forming surface selected from the group of three-dimensional surfaced belts, metal drums, wire screens, and three-dimensional image transfer devices.

3. A three-dimensionally imaged disposable blanket as in claim 2, wherein said forming surface is a three-dimensional image transfer device.

4. A three-dimensionally imaged disposable blanket as in claim 1, wherein said blanket has a basis weight of about 85-130 grams per square meter.

5. A three-dimensionally imaged disposable blanket as in claim 1, wherein said thermoplastic continuous filaments are selected from the group consisting of polyolefins, polyamides, polyesters, and the combinations thereof.

6. A three-dimensionally imaged disposable blanket as in claim 5, wherein said polyolefins are selected from polypropylene, polyethylene, and the combinations thereof.