Textiles: manufacturing – Textile product fabrication or treatment – Fiber entangling and interlocking
Reexamination Certificate
1999-06-29
2001-11-13
Vanatta, Amy B. (Department: 3765)
Textiles: manufacturing
Textile product fabrication or treatment
Fiber entangling and interlocking
C028S105000
Reexamination Certificate
active
06314627
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to non-woven fabrics. In particular, the present invention relates to hydroentangled non-woven composite fabrics.
BACKGROUND OF THE INVENTION
Non-woven fabrics are well known in the art. Because of their relative low cost of manufacture and their ability to be designed for particular applications, non-woven fabrics are widely used in a number of consumer and industrial purposes. As an example, non-woven fabrics are frequently used to fabricate wipes for sanitary, industrial, and consumer applications that include collecting solid matter.
Present non-woven wipes suffer several disadvantages, however, particularly when used to wipe solid or semi-solid matter. As a wipe is often used to remove materials such as dirt, grease, or even fecal matter, the wipe desirably should have a surface that is efficient for collection of such matter. In addition, for sanitary reasons, the wipe should be relatively impenetrable and impervious to such matter. To a practical extent, these two desirable qualities are mutually exclusive. A loosely bound non-woven fabric with a surface having a three dimensional texture or apertures is generally efficient at collection of solid matter. Non-woven fabrics prepared by hydroentangling fibers may be particularly well suited to achieve these qualities. Hydroentangling is well known in the art, and is described, for instance, in U.S. Pat. No. 3,485,706 to Evans, herein incorporated by reference.
Fabrics with such qualities, however, also tend to promote porosity of the fabric to the solid matter. More tightly bound non-woven fabrics without apertures and which tend to have a smooth surface, on the other hand, are much more impervious to passage of solid matter. The fabric's smooth surface, however, is less efficient for wiping, particularly where the material to be collected is a semi-solid with a tendency to smear upon wiping, such as grease or fecal material.
Present non-woven wipes generally place a higher value on sanitary needs than on wiping efficiency. That is, present non-woven wipes generally sacrifice wiping efficiency to insure high resistance to penetration of the fabric. Thus present non-woven wipes generally comprise tightly bound, smooth-surfaced fabrics. While these fabrics are efficient at preventing matter from passing through, as previously noted, they are inefficient at collecting such matter. Often several individual wipes must be used to completely clean a surface. These problems are particularly acute for baby wipes designed for wiping fecal matter from a baby, where penetration through the wipe of the solid or semi-solid fecal matter is most disadvantageous.
The prior art does include many examples of composite fabrics that may comprise a loosely entangled non-woven layer and a more resilient scrim. These fabrics, however, are generally configured for adsorbency, and are not well suited for wiping to collect solids or semi solids. The scrim is generally provided only for reinforcement, and comprises a fairly stiff and heavy element not appropriate for a wipe.
There is therefor an unresolved need for an improved non-woven fabric.
OBJECTS OF THE INVENTION
It is an object of the invention to provide a non-woven composite fabric having at least a first structured surface layer efficient at wiping solid or semi-solid matter and at least a second non-woven layer that is substantially impermeable to such matter.
It is a further object of the invention to provide a method for making a non-woven composite fabric having at least a first structured surface layer efficient at wiping solid or semi-solid matter and at least a second non-woven layer that is substantially impermeable to such matter.
SUMMARY OF THE INVENTION
The present invention generally comprises a non-woven composite fabric, as well as a method for making a non-woven composite fabric. The fabric of the invention comprises a first hydroentangled non-woven layer with a structured surface having a basis weight of at least 10 gm/m
2
, and a second non-woven layer also having a basis weight of at least 10 gm/m
2
that is substantially impenetrable to solids and semi-solids. The first non-woven layer is very efficient for the wiping of solid or semi-solid matter because of its structured surface, while the second non-woven layer that is substantially impermeable to the solid or semi-solid matter prevents such matter from penetrating through the fabric. Thus a composite non-woven fabric results that is both efficient at wiping of solid or semi-solid material, and that is sanitary for holding and wiping.
As used herein, “structured surface” is intended to refer to either a three dimensional quality of a fabric surface, and/or to a surface that has a regular pattern of apertures. A three dimensional surface quality exists when a substantial portion of the surface is on a plane above a separate surface portion. The surface of the fabric is thus non-planar in that it exists in multiple planes. That is, the fabric surface has a portion that is raised from the surface base that may comprise for example, a series of ridges, bumps, or other geometric configurations. Further, it is intended that the different portions are discernable to an unaided human eye upon inspection. As is known in the art, there are various ways to produce fabrics with such surfaces. In particular, structured surface non-woven fabrics may be formed by transferring a pattern from a forming support, which may comprise a textured forming belt or drum, for instance. An example of hydroentangling fibers supported on a three dimensional forming surface is described in detail in U.S. Pat. Nos. 5,098,764 and 5,674,591, herein incorporated by reference.
Further, “structured surface” is also intended to refer to a fabric surface having a regular pattern of apertures. As is known in the art, fabrics with such surfaces may be formed by hydroentangling fibers supported on a surface having raised portions and recessed void areas disposed among the raised portions. The recessed void areas may comprise apertures. For example, a suitable support surface may comprise a surface with an aperture pattern such as a wire mesh forming belt. Producing non-woven fabrics using such support surfaces is known in the art, and is described in U.S. Pat. No. 4,741,941, herein incorporated by reference.
It has been discovered that fabrics having structured surfaces as described above are far more efficient at collecting solid or semi-solid materials than are fabrics with a substantially “flat” or un-structured surface. The increased surface area and various angled surface portions are thought to be advantageous in attaching and retaining solid or semi-solid material, particularly when wiping such materials which tend to smear.
A preferred embodiment of the fabric of the invention comprises three laminated non-woven layers, with first and third hydroentangled non-woven layers sandwiched about a second layer. In this preferred embodiment, the first and third layers have structured surfaces, individual basis weights of between about 20-40 gm/m
2
, and a wiping efficiency (as will be described below) ratio to the second layer of at least 1.25:1 when tested with solid or semi-solid matter. The second non-woven layer is substantially impenetrable to passage of solids or semi-solids, and has a basis weight of between 20-40 gm/m
2
. All three non-woven layers of this preferred embodiment are comprised of staple fibers of cellulosic rayon, polyolefin, polyester, or mixtures thereof.
Because of its unique qualities, the fabric of the invention may find particular utility when used as a baby wipe for collecting fecal matter.
The method of the invention generally comprises the steps of forming a first non-woven web by hydroentangling staple fibers on a forming belt, cylinder, or drum, with the resultant first web having a structured surface and a basis weight of at least 10 gm/m
2
. An additional step comprises forming a second non-woven web that is substantially impenetrable to solids or semi-solids, and tha
Polymer Group Inc.
Pyle & Piontek
Vanatta Amy B.
LandOfFree
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