1. Field of the Invention
The present invention relates to a coil link fabric, and, more particularly, to such a fabric having stuffers inserted into open areas to reduce the permeability of the fabric.
2. Description of the Related Art
Fabrics wound with coiled filaments that require lower permeability such as used in dryers, PMC, and other non-woven industries are stuffed with fibers of the monofilament or multifilament type to fill the open spaces in the coils of the fabric. These stuffers may be braided or extruded, and in a variety of elongated solid geometric shapes. When significantly lower permeability is required, it is difficult to seal all the openings in the fabric. This is because the fabric needs to be stuffed and then heat set to a high temperature to shrink the coiled fabric onto the stuffer and close the open spaces in the fabric structure. The complex geometric shapes used in the past are difficult to insert in the open spaces. Even with the elaborate procedure to fill the open spaces, the resultant permeability is still not low enough because the stuffers do not conform to the curved and intricate shapes of the coiled monofilaments.
What is needed in the art is a fabric of the above type having a significantly lower permeability and which is made using a simplified process.
The invention, in one form, is directed to a fabric having a plurality of coiled monofilaments arranged in side-by-side intermeshing relationship and having elongated pintles extending through intermeshed portions of the coils. Elongated tubular stuffer elements extend through central portions of each of the coils. The monofilaments are heat set to form the fabric and the stuffer elements are formed from a material having a glass transition temperature at around the temperature at which the monofilaments are heat set so that the stuffer elements deform to fill voids between the coil elements.
The invention, in another form, is directed to a method for forming a low permeability fabric having the steps of arranging a plurality of coiled monofilaments in side-by-side intermeshing relationship. Pintles are extended through intermeshed portions of the coiled monofilaments and tubular stuffer elements are extended through central portions of the coiled monofilaments. The monofilaments are heat set at an elevated temperature with the tubular stuffer elements formed from a material having a glass transition temperature at about the elevated temperature for the coiled monofilaments, whereby the tubular stuffer elements are deformed to fill the central portion of the coiled monofilaments.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
Referring now to the drawings, and more particularly to
After the coiled monofilaments 14 are interweaved and the pintels 18 are inserted, the tubular stuffers 10 are inserted in a CMD fashion. The material of the stuffer element 10 is a polymer selected from a broad range of materials so that its glass transition temperature Tg is approximately at the temperature at which the polyester monofilaments are heat set. Examples of polymers used for this purpose may be polyethylene terephthalate (PET), PCTA, polyphenylene sulfide (PPS), flurolpolymers and nylons.
The coiled polymer monofilaments 14 have a heat set temperature around approximately 420° to 460° F. The glass transition point is defined as Tg is the temperature below which molecules have little relative mobility. Above Tg, secondary non-covalent bonds between polymer chains become weak in comparison to thermal motion and the polymer becomes rubbery and capable of elastic or plastic deformation without fracture. The glass transition temperature Tg is below the melting temperature Tm. It is the selection of a material with a glass transition temperature Tg to deform and fill the voids in the coiled monofilaments to more effectively reduce permeability during the heat set process of the fabric 12. Because the stuffer elements 10 are tubular, they are much more able to be deformed in the machine direction (MD) then a solid stuffer would be.
This is shown in
The configuration of the tubular stuffer element 10 may be circular in cross-section or have an oval shape 20 as shown in
While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.