Multicomponent fibers and microdenier fabrics prepared by fibrillation thereof

Abstract

Multicomponent fibers and fabrics made therefrom are provided. The fibers include a multilobal sheath fiber component surrounding a core fiber component, wherein the fibers can be fibrillated to provide a plurality of intertwined microdenier fiber components. Methods of providing such fabrics are also disclosed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of U.S. application Ser. No. 12 / 543,636, filed Aug. 19, 2009, which is a continuation-in-part of U.S. application Ser. No. 11 / 769,871, filed Jun. 28, 2007, which is a continuation-in-part of U.S. application Ser. No. 11 / 473,534, filed Jun. 23, 2006, which claims priority to U.S. Prov. Appl. Ser. No. 60 / 694,121, filed Jun. 24, 2005, all of which are incorporated herein by reference in their entireties.FIELD OF THE INVENTION[0002]The invention relates generally to the manufacture of microdenier fibers and nonwoven products manufactured from such fibers. The fibers may contain one or more elastomers and / or particulate additives.BACKGROUND OF THE INVENTION[0003]Nonwoven spunbonded fabrics are used in many applications requiring a lightweight disposable fabric. Therefore, most spunbonded fabrics are designed for single use and are designed to have adequate properties for the applications for which they are in...

AI Technical Summary

Benefits of technology

The present invention provides multicomponent fibers that can be fibrillated to form fiber webs with high strength and durability. The fibers have a bicomponent core that is encapsulated by a sheath fiber component. The core and sheath fiber components can be made from different thermoplastic polymers, and the fibers can be used to make spunbonded fabrics with excellent properties. The invention also provides a method for making the fibers and fabrics.

Problems solved by technology

This is partly because the elastomers do not solidify, crystallize rapidly, and remain tacky.

Thus, during extrusion, the elastomers tend to stick together and form bundles, which results in poor fabric formation.

To date, spunbonded elastomers where the elastomer is exposed have not been produced successfully in nonwovens.

However, high concentrations of additives within the polymer can result in fibers breaking during extrusion.

In bicomponent fibers, such additives have previously been added to the core or the sheath in small quantities, but in splittable fibers, the addition of such additives typically results in fiber breakage during extrusion.

Consequently, if the components selected do not have properties which are closely analogous, the continuous fiber may suffer defects during manufacturing such as breaking or crimping.

Such defects would render the filament unsuitable for further processing.

This fiber is anisotropic and is difficult to process as a staple fiber, but can work as a continuous filament.

Another disadvantage utilizing segmented pie configurations is that the overall fiber shape upon splitting is a wedge shape.

Such shapes are currently unavailable under standard segmented processes.

Accordingly, when manufacturing microdenier fibers utilizing the segmented pie format, certain limitations are placed upon the selection of materials.

If the materials are too dissimilar, the fibers will break during processing.

Such a process is not environmentally friendly as an alkali solution is often utilized, which may require wastewater treatment.

Additionally, since it is necessary to expose the island components to the solvent that dissolves the sea, this method restricts the types of polymers which may be utilized as islands to those not affected by the solvent that dissolves the sea.

In summary, what has been accomplished so far has limited application because of the limitations posed by the choice of the polymers that would allow ease of spinning and splittability for segmented fibers.

The spinning is problematic because both polymers are exposed on the surface and therefore, variations in elongational viscosity, quench behavior, and relaxation cause anisotropies that lead to spinning challenges.

Furthermore, the incorporation of elastomer-containing components and additive-containing polymeric components within the fibers has been problematic.

When a fiber contains additive-containing polymeric components, the additive concentration within the fiber is limited due to the likelihood of fiber breakage during extrusion.

Still further, a major limitation of the current art is that the fibers form wedges and there is no flexibility with respect to fiber cross sections that can be achieved.

However, with the requirement of removing the sea, limitations exist due to limited availability of suitable polymers for the sea and island components.

Prior to the inventive activity set forth in the related patent applications, islands in the sea technology has not been employed for making microdenier fibers other than via the removal of the sea component because of the common belief that the energy required to separate the islands from the sea renders this process commercially unviable.

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