Textiles: cloth finishing – Miscellaneous
Reexamination Certificate
2002-02-27
2004-04-06
Worrell, Danny (Department: 3765)
Textiles: cloth finishing
Miscellaneous
C028S167000
Reexamination Certificate
active
06715189
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to specific, improved spun-bonded nonwoven fabrics comprised of continuous multi-component longitudinally splittable fibers. The resulting nonwoven fabrics exhibit enhanced flexibility, drape, softness, thickness, moisture absorption capacity, moisture vapor transmission rate, and cleanliness in comparison with other nonwovens of the same fiber construction. These improved aesthetic and performance characteristics permit expansion of high-strength nonwoven fabric materials into other markets and industries currently dominated by woven and knit fabrics that exhibit such properties themselves, but at high cost and requiring greater manufacturing complexity. Such enhanced fabrics are subjected to certain air impingement procedures, for instance through directing low-pressure gaseous fluids at high velocity to the surface of the targeted nonwoven fabric. Also encompassed within this invention is the method of treating such a specific nonwoven fabric with this air impingement procedure.
Nonwoven textile articles have historically possessed many desirable attributes that led to their use for many items of commerce, such as within air filters, furniture linings, and automotive parts, such as vehicle floorcoverings, side panels, and molded trunk linings. Such nonwovens have proven to be lightweight, inexpensive, and uncomplicated to manufacture, among various other advantages.
Recently, technological advances in the field of nonwovens, such as improved abrasion resistance and wash durability, have expanded the markets for such materials. For example, U.S. Pat. Nos. 5,899,785 and 5,970,583, both assigned to Firma Carl Freudenberg, describe a nonwoven lap of very fine continuous filament and the process for making such nonwoven lap using traditional nonwoven manufacturing techniques. Such references disclose, as important raw materials, spun-bonded composite, or multi-component, fibers that are longitudinally splittable by mechanical or chemical action. Furthermore, patentees indicate the ability to subject a nonwoven lap, or fabric, formed from such materials to high-pressure water jets (i.e., hydroentanglement). This further treatment causes the composite fibers (which are typically microdenier in size) to partially separate along their lengths and become entangled with one another, thereby imparting strength to the final product. As an example, Freudenberg currently commercializes at least one product, Evolon®, made by this process, and it is available in standard or point-bonded variations. (The standard variation has not been subjected to further bonding processes, such as point bonding. Point-bonding is the process of binding thermoplastic fibers into a nonwoven fabric by applying heat and pressure so that a discrete pattern of fiber bonds is formed.) Additionally, U.S. Pat. No. 6,200,669, assigned to Kimberly-Clark Worldwide, Inc., describes yet another process for fabricating spun-bonded nonwoven webs from continuous multi-component fibers that are longitudinally splittable by the process of hydroentanglement.
These manufacturing techniques permit efficient and inexpensive production of nonwoven fabrics having characteristics and properties, such as, for example, mechanical resistance, equal to those of woven or knitted fabrics. As a result, such nonwovens have penetrated markets, such as apparel, cleaning cloths, and artificial leather, which historically have been dominated by woven and knit products.
However, with the emergence of nonwovens into these new markets and increased consumer interest in such products, there has been a desire to produce fabrics with additional characteristics similar to those of woven or knitted fabrics. Some of these characteristics include increased flexibility, drape, and softness of the fabric. Historically, these attributes have been obtained subsequent to the fabric's finishing (i.e. after finishing processes which include, for example, dyeing, decorating, texturing, etc.) with some difficulty due to the fragile nature of the fabric and the ease of mark-off of any dyes, pigments, or other decorative accoutrements. Prior methods of fabric conditioning after finishing have included roughening of the finished product with textured rolls or pads, which may actually break a significant number of surface fibers. These methods, as mentioned above, may be destructive to the finished fabric because of such problems as undue weakening of the overall strength of the fabric and mark-off.
Additionally, other methods for conditioning include the use of chemicals, which can be expensive, detrimental to the environment, and irritating to the skin. Thus, a chemical-free process, which involves no contact with rough surfaces, is preferable in order to reduce or eliminate skin irritation and minimize damage to the surface of the fabric while providing optimal levels of softening and conditioning to the fabric. Commonly assigned U.S. Pat. Nos. 4,837,902, 4,918,785, 5,822,835, and 6,178,607 have identified techniques for conditioning textile webs, or fabrics, to change their aesthetic and performance qualities. Specifically, these patents disclose methods and equipment for projecting low pressure, high velocity streams of gaseous fluid against a fabric web in either the opposite or same direction substantially tangential to the web of fabric, thereby creating saw-tooth waves having small bending radii which travel down the fabric thereby breaking up, or weakening, some fiber-to-fiber bonds in the web so as to increase flexibility, drape, and softness of the fabric. An additional attribute imparted to the fabric treated by these processes of air impingement includes increased cleanliness of the fabric due to the removal of undesired fiber fly and other loose materials entrapped in the pile.
Thus, while nonwoven manufacturing technology has been identified which has allowed for the introduction of nonwoven textile fabrics into new market areas such as apparel, cleaning cloths, and artificial leather, consumer interest has spurred the need for further advances in the finishing of these fabrics in order to improve the look and feel of the fabric for emergence into additional markets and end-use products for apparel, napery, drapery, upholstery, cleaning cloths, and cleanrooms.
SUMMARY OF THE INVENTION
In light of the foregoing discussion, it is one object of the current invention to achieve a spun-bonded nonwoven fabric comprised of continuous multi-component splittable fibers, which has been mechanically modified to possess increased flexibility and drape.
A further object of the current invention is to achieve a spun-bonded nonwoven fabric comprised of continuous multi-component splittable fibers, which has been mechanically modified to possess increased softness and thickness.
It is also an object of the current invention is to achieve a spun-bonded nonwoven fabric comprised of continuous multi-component splittable fibers, which has been mechanically modified to possess increased moisture absorption capacity and moisture vapor transmission rate.
Another object of the current invention is to achieve a spun-bonded nonwoven fabric comprised of continuous multi-component splittable fibers, which has been mechanically modified to possess increased cleanliness due to the removal of loose materials trapped in the fabric.
A further object of the current invention is to achieve a spun-bonded nonwoven fabric comprised of continuous multi-component splittable fibers, which has been mechanically modified and that maintains its aesthetic appearance due to the finishing process having no physical contact with the surface of the fabric.
It is also an object of the current invention to achieve a method for mechanically modifying spun-bonded nonwoven fabrics comprised of continuous multi-component splittable fibers to impart increased flexibility, drape, softness, thickness, moisture absorption capacity, moisture vapor transmission rate, and cleanliness to the fabric.
Other objects, advantages, and features of the current inv
McDaniel John Scott
Osbon Robert Lindsay
Milliken & Company
Moyer Terry R.
Wentz Brenda D.
Worrell Danny
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