US3515623A - Woven fabric having bonded crossovers and method of forming same - Google Patents

Description

June 2, 1970 r T. E. BATES 3,5

WOVEN FABRIC HAVING BONDED CRQSSOVERS I AND METHOD OF FORMING SAME Filed Feb. 25, 1967 I NVENTOR pm; I THOMAS Bugs ATTORN Y5 United States Patent O 3,515,623 WOVEN FABRIC HAVING BONDED CROSSOVERS AND METHOD OF FORMING SAME Thomas E. Bates, Anderson, S.C., assignor to Clark- Schwebel Fiber Glass Corporation, Anderson, S.C.,

a corporation of New York Filed Feb. 23, 1967, Ser. No. 617,959 Int. Cl. B321) 17/04; D03d 25/00 U.S. Cl. 161-86 14 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION The invention is concerned with Woven fabric manufacture utilizing inorganic warp and weft, such as glass fiber, that is commonly subject to objectionable disarrangement or raveling during use of the fabric, particularly when the fabric is of open-mesh or scrim character.

Glass fiber scrim fabrics are used to a considerable extent as an internal reinforcing mesh in plied roofing papers and heavy-duty wrapping papers and the like, and these scrim fabrics are needed for such use in a running width corresponding to that of the papers they are to reinforce, which is usually no more than half the width that may be woven readily on conventional looms. Other uses of glass fiber fabric call for even narrower running widths, so that it is common practice to weave the fabric as nearly as possible at the full width capacity of the loom, and then slit the woven web warpwise into the narrower width or widths desired. The result of such practice, however, is at least one internal selvage at which the Weft is cut and which exhibits a troublesome tendency toward raveling under the best of circumstances, while being substantially unmanageable when a slick fiber like glass is involved.

Leno or doup treatment of the warp ends adjacent the cut selvage has previously been employed to combat this difiiculty, but the result is still not sufficient where the openness of the fabric is substantial or the fiber ends are particularly slick. The prior art also includes proposals for bonding the warp and weft crossovers in the fabric to provide security against raveling, as in U .S. Pats. No. 3,061,907 and No. 2,840,117, but such prior proposals have depended on a thermoplastic or solvent-sensitive character in the warp and weft, or on auxiliary Warp remaining as warp in the finished fabric, or on applying supplementary edging material to the fabric.

It has remained for the present invention to deal with this problem effectively in a manner that still leaves the fabric structure normal and appearing, unless examined closely, as if it were no different than usual.

SUMMARY OF THE INVENTION The woven fabric of the present invention is characterized by inorganic warp and weft having bonded crossovers that are developed during the weaving operation without disturbing normal weaving procedures and without qualifying the usual form or appearance of the fabric in any apparent respect.

Glass fiber is the inorganic warp and weft for which the invention was conceived and with which it is currently being used, but the invention is likewise applicable for any other inorganic strand material, such a those prepared from quartz, boron or carbonaceout materials, as well as metallic wire for screening and the like. It is only necessary that the warp and weft be structurally insensitive to the heat required to effect bonding of the crossovers The bonded crossovers result from deposits thereat of thermoplastic material derived from a thermoplastic strand or strands associated with a selected warp end or ends during weaving. Depositing of the bonds at the crossovers is accomplished by locally melting the thermoplastic strand material as the woven fabric progresses from beat-up to take-up. The thermoplastic strand material is suitably nylon, and preferably a stretch nylon, but it may alternatively be any other stranded thermoplastic material, such as polyester, that melts before burning at a temperature ranging below about 500 F.

Association of the thermoplastic strand material for weaving with the selected warp is readily effected either by introducing this strand material as a doup end or by plying it beforehand with the warp end or ends selected. As previously noted, the invention offers particular advantages for stabilizing the warp ends adjacent a cut selvage.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic illustration of the manner in which the woven fabric of the present invention is formed;

FIG. 2 is an exaggerated detail illustrating fabric structure formed in the FIG. 1 manner when the thermoplastic strand material has been associated as a doup end and before it has been melted;

FIG. 3 is a corresponding detail indicating the fabric structure form when the thermoplastic strand material has been plied; and

FIG. 4 is a further detail of the same sort representing the resulting fabric structure after the thermoplastic strand material in either the FIG. 2 or 3 forms has been melted and an adjacent internal selvage has been cut.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The FIG. 1 illustration diagrams a weaving operation of conventional character in which a warp beam A is arranged to let-off a warp sheet B for shedding from a lease rod position C by harness means at D. The warp sheet B is composed of the inorganic warp with which the present invention deals, and the related inorganic weft (not illustrated) is introduced by picking correlated to the shedding, with each inserted weft pick being beatup at the E position, by a reed carried on an oscillating lay in conventional fashion, to form woven fabric F that progresses over a breast beam G and downwardly therefrom at F to a take-up roll H having a guide bar or roll I thereat for maintaining an effective extent of warp about the take-up roll H as the fabric F is delivered therefrom for building the fabric roll J.

A spool K is indicated in FIG. 1 from which the thermoplastic strand material is supplied for incorporation in the fabric F either by doup treatment at the harness means D in relation to the selected warp, or by separate introduction therewith in plied form. In either case, a separate spool K or comparable supply arrangement is employed, as the thermoplastic strand material will constitute or be included in a dissimilar Warp end or ends that cannot be handled evenly on the warp beam A.

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Local melting of the thermoplastic strand material for crossover bonding as the fabric F progresses from heatup to take-up is accomplished by simply disposing a heating element L to contact the fabric F as it passes thereover. The heating element L is suitably of the electrical resistance type, preferably fitted to deliver the heat through a cylindrical contact housing having a diameter in the order of 1 /2" so that the fabric F will ride thereover readily. The heating element L is conveniently mounted adjacent the breast beam G to contact the fabric F before it turns downwardly thereover for take-up. The contact housing as well as the heating element L as a whole may be fixed so that it remains stationary as the fabric F rides thereover. The heating element L must of course have a sufiicient capacity for delivering enough heat to the fabric P so that the thermoplastic strand material is subjected to melting temperature conditions.

When the woven fabric F is to be slit into narrower widths, this is done during take-up after the crossover bonding has been accomplished. An effective slitting arrangement is the fixed disposition of a suitably sharp cutting element M in the path of the fabric F as it passes from the guide bar I to the fabric roll I.

The invention has been applied representatively in weaving a glass fiber scrim fabric using ECG 150 1/0 1.0Z glass fiber warp and weft, at plain weave sley and pick counts of 20, with 1444 warp ends drawn one end per dent while skipping eight dents centrally in order to provide for slitting an internal selvage, and with a doup warp end of 70/2 stretch nylon forming a three-end leno at each side of the internal selvage spacing.

FIG. 2 illustrates the resulting fabric structure F, the warp being represented at 10, the weft at 12, and the nylon doup ends at 14 associated with two warp ends on each side of the internal selvage space at which eventual slitting is intended along a warpwise axis such as is indicated at 16. FIG. 3 shows an alternative arrangement of the same fabric structure in which a nylon end 18 is plied with each of the warp ends 10* adjacent the internal selvage spacing. This FIG. 3 arrangement has the advantage of eliminating the complication of leno manipulation during the weaving operation; it has the disadvantage of requiring the additional plying operation in preparation for weaving.

Either of the FIG. 2 or FIG. 3 weave arrangements provide effectively for ultimate formation of fabric F (see FIG. 4) incorporating an internal selvage resulting from slitting along the axis 16, and having the two adjacent warp ends 10' bonded securely at each weft crossover by deposits thereat of thermoplastic mate rial derived from the specially associated strands 14 or 18.

The FIG. 4 illustration of the crossover bonds 20 is conceptual or figurative in nature, rather than realistic, for it is not possible to distinguish the bonding deposits readily in a glass fiber fabric F of the sort described above, and it appears that the bonding material. tends to arrange itself between the warp and weft at the crossovers so as not to be nearly so apparent as FIG. 4 indicates.

Depositing of the bonding material selectively at the crossovers takes place as a matter of course as long as the thermoplastic strand material is associated with the warp to be bonded in a manner causing the involved warp to carry the strand material regularly to the heating element L. As the associated arrangement of the strand material results in bringing it into direct contact with the heating element L at intervals occurring more or less regularly in correspondence with the crossovers, the melting influence of the heating element L has the effect of progressively freeing a short length of the strand material as each crossover passes the heating element L, so that this free, short length tends to spring or contract or curl toward the following crossover.

Additionally, the heating element L heats the warp and weft ends of the fabric structure so as to establish melting conditions indirectly in this way, so that the total elfect on the passing fabric structure is to maintain a tendency for initial redisposition of the strand material toward the crossovers and a melting influence that allows the derived melt to flow thereat to the barrier that each crossover naturally forms. solidification of each selective deposit thus obtained takes place rapidly when the heating element L is passed so that the bonding is fully secure before take-up commences in normal course.

All that happens in the foregoing manner to effect crossover ibonding takes place without requiring any modification of normal weaving procedures, and it is to be noted further in this respect that any usual occasion for stopping the weaving operation is not at all complicated by disposition of the heating element L in contact with the involved portion of the fabric structure beyond beatup, for the main fabric structure is structurally insensitive to the heating influence while the thermoplastic strand material will essentially retain its initial character until it reaches the heating element L.

When the thermoplastic strand material is associated in the fabric in leno fashion, as in FIG. 2, each selvage warp 10' might alternatively have a strand end Woven as a doup therewith, or a single warp 10' and associated doup strand might be employed. Likewise, only one plied Warp 10" might be used in the FIG. 3 fabric form, while still obtaining crossover bonding at the selvage in accordance with the present invention. However, two warp ends 10 are preferably involved as a practical matter, particularly in scrim fabrics, to provide a margin of certainty that regular securing of the selvage will result in the course of a normally tended weaving operation.

It is additionally notable that the three-end leno arrangement of FIG. 2 tends to narrow the spacing between the involved warps 10, and a comparable narrowing results when two plied warp end 10 are employed adjacent an internal selvage spacing as in FIG. 3. It appears that such narrowing increases the stabilizing influence of the crossover bonding at the selvage. In any event, it has been found that either of the FIG. 2 or FIG. 3 arrangements allow the internal selvage spacing to be safely reduced in width considerably below the usual requirement, with a resulting advantageous reduction in the length of the protruding cut ends of the weft at the selvage after slitting.

The present invention has been described in detail above for purposes of illustration only and is not intended to be limited by this description or otherwise except as defined in the appended claims.

What is claimed is:

1. A method which comprises weaving a fabric of inorganic warp and weft having a strand of thermoplastic material associated with at least one end of said warp and then, after beating-up but before take-up, progressively melting said thermoplastic strand locally and completely as the woven fabric structure passes and thereby causing the thermoplastic material to move toward the adjacent crossover for selectively depositing a bond derived from the thermoplastic material of said strand to secure said associated warp end at each weft crossover.

2. The method defined in claim 1 and further characterized in that said warp and weft is formed of glass fiber.

3. The method defined in claim 1 and further characterized in that a nylon strand is employed for association with said warp end.

4. The method defined in claim 3 and further characterized in that said nylon strand is a stretch yarn.

5. The method defined in claim 1 and further characterized in that said thermoplastic strand is associated by weaving it as a doup end.

6. The method defined in claim 1 and further characterized in that said thermoplastic strand is associated by plying it with said warp end in preparation for weaving.

7. The method defined in claim 1 and further characterized in that said thermoplastic strand is associated with a warp end adjacent a selvage at which the weft is cut.

8. The method defined in claim 1 and further characterized in that said warp and weft is woven to form a scrim fabric.

9. A woven fabric formed of inorganic warp and weft, and in which fabric at least one warp end is secured at each weft crossover by a bond of thermoplastic material deposited selectively and exclusively thereat by the method defined in claim 1.

10. A woven fabric as defined in claim 9 and further characterized in that said warp and weft is formed of glass fiber.

11. A woven fabric as defined in claim 9 and further characterized in that the material forming said bond is nylon.

12. A woven fabric as defined in claim 9 and further characterized in that said fabric has at least one selvage at which the weft is cut, and in that said secured warp end is adjacent said selvage.

13. A woven fabric as defined in claim '12 and further characterized in that two warp ends adjacent said selvage are secured at each warp crossover.

14. A woven fabric as defined in claim 12 and further characterized in that said fabric is a scrim fabric.

References Cited UNITED STATES PATENTS ROBERT F. BURNETT, Primary Examiner M. A. LITMAN, Assistant Examiner US. Cl. X.R.

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