US3695983A

US3695983A - Woven article as a carpet scrim

Info

Publication number: US3695983A
Application number: US69508A
Authority: US
Inventors: William J Hogg; Charles A Jackson; Septimus A Harvin; Joseph C Whitesel
Original assignee: Thiokol Corp
Current assignee: WT ACQUISITION Inc; ATK Launch Systems LLC
Priority date: 1970-08-10
Filing date: 1970-08-10
Publication date: 1972-10-03
Anticipated expiration: 1989-10-03
Also published as: CH1148771A4; ZA714378B; DE2139674C3; AU3185371A; CA947953A; AU462181B2; DE2139674A1; DE2139674B2; CH603857B5; NL7110735A; BE771081A; LU63683A1; FR2104140A5; CH582776A5; GB1362684A

Abstract

A BACKING OR SCRIM WOVEN FROM YARNS OF SYNTHETIC PLASTIC, USEFUL IN PARTICULAR FOR NEEDLE PUNCH CARPET PRODUCTS AND THE LIKE IS DISCLOSED. THE INVENTION IS CHARACTERIZED BY THE YARNS IN THE WARP OF THE SCRIM BEING "CROWDED" AND DIMENSIONALLY SELECTED TO HAVE A WIDTH TO THICKNESS RELATIONSHIP TO INSURE MINIMUM FOLDOVER, THEREBY RESULTING IN A LOOSE WARP, DESPITE CROWDING AND POSSESSING A HIGH DEGREE OF "SPRINGINESS" TO INHIBIT WIDTH REDUCTION DUE TO MECHANICAL WORKING WHEN WOVEN AND USED IN THE CARPET PRODUCT. A FURTHER CHARACTERISTIC IS THE USE OF A HEAT SOAKED FILL YARN, WHEREIN THE HEAT SOAKING IS ACCOMPLISHED PRIOR TO WEAVING, TO REDUCE SHRINKING IN THE FILL DIRECTION.

THE FINAL SCRIM FABRIC IS REMARKABLY NON-SHRINKABLE, EVEN WHEN SUBJECTED TO HOT LATEXING AND DYEING PROCEDURES IN CARPET MANUFACTURE.

Description

Oct. 3, 1972 w. J. HOGG ETAL 3,695,983

WOVEN ARTICLE AS A CARPET SCRIM Filed. Aug. 10, 1970 4 Sheets-Sheet 1 INVENTORS WILL/AM J. H066 SEPT/MUS A. HARV/N CHARLES .4. JL4CK$0N JOSEPH C WH/TESEL Oct. 3, 1972 w HOGG ET AL 3,695,983

WOVEN ARTICLE AS A CARPET SCRIM INVENTORS' WILL/AM .1 H066 SEPT/MUS A. HARw/v,

CHARL E5 A. JACKSON JOSEPH a. WH/TESEL Oct. 3, 1972 w J HOGG ETAL 3,695,983

WOVEN ARTICLE AS A CARPET SCRIM Filed Aug. 10, 1970 4 Sheets-Sheet :5

INVENTORS WILLIAM J. H066 SEPT/MUS A. HARV/N CHARLES A. JACKSON JOSEPH C. WH/TESEL Oct. 3, 1972 w J HOGG ET AL 3,695,983

WOVEN ARTICLE AS A CARPET SCRIM Filed Aug. 10, 1970 4 Sheets-Sheet 4 I. I. I. 5972 Fig.6

INVENTORS WILL/AM J. H066 SEPT/MUS A. HARVl/V;

CHARLES A. JACKSON JOSEPH C. WH/TESEL m? mmwwwm Unease-es Patent one 3,695,983 Patented Oct. 3, 1972 3,695,983 WOVEN ARTICLE AS A CARPET SCRIM William J. Hogg, Dalton, and Charles A. Jackson,

Sterling, N.J., and Septimus A. Harvin and Joseph C.

Whitesel, Waynesboro, Va., amignors to Thiokol Chemical Corporation, Bristol, Pa.

Filed Aug. 10, 1970, Ser. No. 69,508 Int. Cl. D03d 11/00, 13/00; B32b /00 U.S. Cl. 161-71 15 Claims ABSTRACT OF THE DISCLOSURE A backing or scrim woven from yarns of synthetic plastic, useful in particular for needle punch carpet products and the like is disclosed. The invention is characterized by the yarns in the warp of the scrim being crowded and dimensionally selected to have a. width to thickness relationship to insure minimum foldover, thereby resulting in a loose warp, despite crowding and possessing a high degree of springiness to inhibit width reduction due to mechanical working when woven and used in the carpet product. A further characteristic is the use of a heat soaked fill yarn, wherein the heat soaking is accomplished prior to weaving, to reduce shrinking in the fill direction.

The final scrim fabric is remarkably non-shrinkable, even when subjected to hot latexing and dyeing procedures in carpet manufacture.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a new and improved textile fabric. More particularly it relates to a novel woven scrim for textile fabrics such as carpets and the like, formed by the needling, or needle punching process. It also relates to a process for making the scrim, and to a carpet fabric made therefrom. In its carpet fabric aspect the invention is made from a loose batt, or web of semiparallel fibers as obtained from a garnet or textile carding machine. The fibers in the batt can be natural, e.g., wool, cotton or synthetic staple such as is used for outdoorindoor carpeting. The batt of fibers is layed onto, or over the novel plastic scrim, and the loaded scrim is then fed into a needling, or needle punching machine. The needles, usually numbering in the thousands, punch the batt into and through the scrim so that a mass of face fibers covers the top, and to a lesser degree the underside thereof. The punched scrim may be turned over and the process above described repeated; however, punching from one side only is also feasible and some carpets are so made. The underside of the fabric is then usually given a coat of latex which serves to hold the fibers in the fabric body. An additional bottom layer of foam rubber or other backing material may be attached adhesively to complete the carpet fabric.

DESCRIPTION OF THE PRIOR ART The above referred to invention also includes within its scope a significantly improved scrim useful in the particular textile fabric above mentioned. Needle punching in the art of textile manufacturing has been known for many years in felt making and in conjunction with fibers having felt characteristis. For example, Simpson, H. B. et al. in their U.S. Pat. No. 3,484,283 disclose a plastic felt comprised of staple formed into a batt. The batt is then layed over a scrim and fed to needling machines and needle punched in the conventional manner. The fabric made by the method of Simpson et al. is preferably used in outdoor-indoor carpeting, hence polyolefin materials are recommended to be used. J. Zocher, in U.S. Pat.

3,473,205 also discloses a needle punched fabric together with an apparatus for needle punching felt or fiber material into the fabric. Zocher feeds a web of tangled fiber material which is either prepunched to give it solidity, or has been compacted to render it capable of easy transport to the needle machine. The needle machine is modified by means of additional barbs on the needles which pick up additional staple fibers which are stored on a fixed part of the machine and punches them into the web above described. Tesch, G. H., in U.S. Pat. 3,448,502 discloses a needle punched fabric with a plastic sheet scrim which contains slits to improve its needle punching characteristics. Tesch utilizes What he calls a polypropylene foil as scrim, the foil being an oriented plastic film containing diagonal slits, and which is exposed to hot air and/or infrared radiation. The Width of the foil is thereby reduced by about 30%, and its Weight per unit area being reduced to approximately 50 grams per square meter from an original weight per unit area of 350 grams per sq. meter. The slits in the polypropylene scrim are alleged to improve its resistance to splittering during needle punching. Charlton, Jr., R. H., et al., in U.S. Pat. 3,476,626 disclose a needle punched plastic panel having textile simulating characteristics. Charlton et al. provide a rigid (40 mils or more in thickness), but flexible, scrim upon which is layed a fiber web, or batt which is needle punched into the sheet. Provision is also made for heating the scrim for softening thereof prior to needling.

Other needle punched fabrics are known to the art, as are fabrics having polyolefin scrims. In fact such scrims have been in use for the past several years. In particular, a woven scrim of polyolefin yarns made on a conventional shuttle loom, the yarns being extruded ribbons, has also recently come into more or less general use. In fact a scrim Woven on a conventional shuttle loom using polyolefin ribbon yarns in a weave configuration of twelve ends per inch in the warp and eight ends per inch in the weft, or fill (12 x 8 configuration), has performed satisfactorily for the last few years when used in needle punched fabrics.

However, with the recent arrival of the much more economical shuttle-less, high speed looms, such as the so-called Sulzer looms" manufactured and sold throughout the World by Sulzer Brothers Ltd., of Winterthur, Switzerland, and which are capable of weaving the above 12 x 8 scrim fabric, serious problems were unexpectedly encountered when a 12 x 8 scrim was woven by means of this machine. In contrast, woven primary backing of these same materials for tufted carpets did not present any significant problems When changing from shuttle to shuttle-less weaving machines. Other problems were encountered some of which may or may not be related to the change in operation from the old to the new machines for Weaving scrims for needle punched fabrics. Problems which appear definitely related to the new machines include; carpet face unsightliness caused by scrim yarn exposure in the carpet face; shifting of the fiber batt after deposit on the scrim fabric before needling; and filling yarns at the selvages of the scrim fabric being punched or pulled through to the carpet face by the needles. An important aspect of this invention is the overcoming of excessive scrim, and therefore carpet width reduction which appeared to be the result of both the mechanical action of needling and subsequent length, or warp-wise tensions applied thereto in processing, and of heating effects associated with latex application and curing.

SUMMARY OF THE INVENTION An important object of the invention, therefore, is to provide a woven article for a needle punched fabric wherein the arrangement and type of warp and fill yarns is such as to result in a scrim of high commercial quality and improved serviceability.

Another object of this invention is to provide a scrim for a needle punched fabric which though woven on a shuttle-less loom performs commercially satisfactorily.

An additional object of this invention is to provide a needle punched fabric useful as a carpet wherein the scrim therefor is a woven article of thermoplastic material having a crowded warp of ribbon like yarns and a relatively open fill of ribbon-like yarns.

Still another object of this invention is to provide an article of the character described wherein at least the fill yarns are treated prior to Weaving to prevent shrink of the article when used for a scrim in a needle punched fabric.

Yet still another object of this invention is to provide a scrim of the type referred to wherein tentering thereof is eliminated.

A yet additional object of this invention is to provide a woven scrim of the character described wherein the selvage thereof is reinforced and sufiiciently secured to substantially eliminate fill yarn push through to carpet face.

Another object of this invention is to provide a fabric of the character referred to wherein the yarns, warp and fill, are treated with a mineral oil or other non-reacting (to the material of the yarns) substance to improve the fabrics needle punching characteristics.

A still additional object of this invention is to provide a fabric scrim of the character described which possesses high strength retention characteristics after needle punchmg.

Another yet important object of this invention is to provide a process for making a scrim of the character described for use in needle punched fabrics.

Described briefly the article and method of the invention comprises a scrim for a needle punched fabric, the combination of a needle punched fabric together with the scrim, and a process for making the scrim. The scrim of the invention is a woven article, preferably of thermoplastic material such as polyolefin, wherein the number of warp yarn ends per unit length exceeds the number of fill yarn ends, or picks per unit length in a ratio of about 3 to 1, or higher. In addition to the novel warp-to-fill ends per unit length relationship, the invention further contemplates that at least the fill yarns be subject to an additional heat soaking or annealing step prior to weaving, thereby producing a scrim of substantially zero shrink capability.

In describing the present invention certain terms and expressions will be used frequently throughout the specification and claims. It is believed, therefore, that the invention will be better understood in the light of the following definitions which are set forth below in a sincere 4 attempt to promote this understanding and also to give clear evidence of the fact that this invention represents a genuine advance in the needle punching textile .arts.

COVER FACTOR To artisans in the textile arts Cover Factor is a term used to indicate the degree of openness in the Warp, in the fill, or in both of a fabric. It is a dimensionless number obtained as the product of the number of yarn ends per inch (warp or fill) and the yarn width in inches. Thus a fabric having 10 ends per inch in the warp and having a yarn Width of 0.10 inch is said to have a Warp Cover Factor of 1.0. However, it should be noted that heretofore in the art, Cover Factors greater than one are relatively meaningless, since the term is mostly used by artisans concerned with round yarn fabrics, hence a Cover Factor above 1.0 is understood to be a layered fabric rather than an open or closed fabric. Therefore to better distinguish the fabrics embraced by the herein described invention a new term, below defined, will be introduced and used herein.

CROWDEDNESS For the purposes of this invention Crowdedness" is considered a rather apt term selected to assist in describing and understanding an important characteristic of the inventive fabric with respect to the warp and/or fill direction. It is of course related to Cover Factor; however, for purposes herein, it is a more convenient term because, as will become evident, it is more descriptive of the article invented. Also, it too is a dimensionless number, being the product of yarn ends per inch and yarn width, and encompasses openness as Well as closedness or opaqueness. In the example given above, i.e., a warp having 10 yarn ends per inch to include multiple strand yarns as one having one end per inch, and each yarn 0.10 in. in width would have a Crowdedness No. of 1.0. Clearly then, as stated above, Crowdedness Number is the product of the number of yarn ends per inch and the width of the yarn in inches. Obviously for yarns of oval, eliptical, round etc. cross-sections, the dimensions utilized in the calculation of Crowdedness N0. is the axis parallel to the plane of the fabric or the diameter, respectively.

A Crowdedness N0. of less than 1.0 indicates an open warp or fill. For example, a fabric scrim which has a fill of 6 ends (picks) per inch of ribbon monofilaments 0.100 inches (100 mils) in width has a fill Crowdedness No. of 0.60, must be open (in the fill) in the sense that the yarns are spaced apart. Conversely, one having a warp of 30 ends per inch and a ribbon width of 0.050 inch mils) has a warp Crowdedness N0. of 1.50 and must be closed, or for purposes herein must be a crowded warp. The following table sets forth in more detail the foregoing concepts.

Crowdedness Numbers (cover factor) Sample Warp yarns Fill yarns Theoretical experimental Number Number Scrim Ends Yarn thick- Ends Yarn thick- Warp Fill Warp Fill description, per width, ness, per width, ness, direcdireedirecdirecwarp x fill inch inch inch inch inch inch tion tion tion tion scrim Number:

1 12 x 8 12 0.100 0.002 8 0. 100 0.002 1.20 24 x 6 24 050 002 6 100 002 1. 20 24 x 8 24 0. 050 002 8 100 002 1. 20 24 x 11 24 050 002 11 100 002 1. 20 28 x 6 28 041 .002 6 109 .002 1. 15 2B. 7 x 6 28. 7 045 002 6 109 002 1. 29 28. 3 x 7 28. 3 .045 .002 7 108 002 1. 27 29 x 6 29 .048 .002 6 100 .002 1.39 29. 2 x 0 29. 2 048 002 0 100 002 1. 26 30 X 6 30 .048 .002 6 100 .002 1. 44 45 x 9 45 040 .0016 9 090 0019 1.

It should be understood that the above tabulated Crowdedness Nos. are maximum values and are applicable to ribbon yarn which experiences minimal or zero folding, bunching or other coverage reducing effects during weaving. Truly such a perfect scrim is practically, or nearly so, impossible to make; however, as will be seen from what follows, Crowdedness Numbers significantly greater than 1.0 are intended as being within the scope of the invention herein presented.

TENTERING A process wherein a scrim fabric, especially a synthetic plastic fabric, is restrained width-wise, as well as lengthwise while being conveyed over or through a heat zone is known as tentering. The purpose of tentering is to preshrink the Woven fabric so that upon being subjected to heat later in the carpet manufacturing process further shrinking will not occur. Tentering usually involves the provision of a relatively large, and often expensive facility. For example, commercial scrim fabrics for carpets usually are supplied in widths of twelve to'fifteen feet hence, a tentering apparatus, if provided, necessarily must be large enough to handle these scrims.

ANNEALING In the textile arts, especially with regard to synthetics used therein, annealing is a process wherein the yarns are heated for specific times under controlled tension. In this respect tentering, above defined, is equivalent to annealing. With respect to the present invention in its process aspect, annealing is involved with respect to the yarns, mostly the fill yarns, wherein said yarns undergo a novel heating step prior to weaving. Further, it should be noted in connection with this term that in usual synthetic yarn manufacture and textile processes annealing times are rather short, e.g., less than one minute and such annealing is carried out as part of a continuous process in manufacture. The novel means of this invention involves times of many minutes and usually hours. As such it is more analogous to conventional metal annealing, unheard of in textiles, and in this context might as aptly be referred to as heat soaking. Therefore, as will be described more fully, in its process aspects, this invention contemplates such heat soaking or annealing steps, of longer times, and as will be seen, with the yarn immobile.

DENI ER The term used in the textile arts to define textile yarn sizes or fineness Denier as used herein is the weight in grams of 9000 meters of yarn. Thus a 500 denier yarn is a yarn such that 9000 meters of it weighs 500 grams.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 discloses, in cross section along the front edge of a fill yarn, and across the warp yarns, a construction of a needle punched carpet showing the relative positions of a scrim and the upper and lower fiber layers;

FIG. 2 is a top view of a needle punched fabric having portions of the several layers exposed to view;

FIG. 3 is a view of a corner of the scrim of the invention showing one of the selvages thereof and the novel reinforcing wary yarns therefor;

FIG. 4 is a view taken on line 4-4 of FIG. 3;

FIG. 5 is a top view of an interior portion of the invention;

FIG. 6 is a view taken on line 66 of FIG. 5; and

FIG. 7 is a view taken on line 77 of FIG. 5.

DETAILED DESCRIPTION OF THE *INVENTION Referring to FIG. 1, a cross-section of a portion of a carpet, or fabric 10, prepared by a needle punched process is illustrated, which comprises a scrim 15, a batt or web 11 and punched fibers 12 which are directed in and through scrim, or backing 15. The section of the view is considered as being taken across the warp yarns 14 and along the front edge of one of the fill yarns 13. Warp and fill

yarns

14 and 13, respectively form scrim 15 which is a woven fabric. As seen in FIG. 1 the needle punching operation forces some of the fibers or batt 11, such as fibers -12 to be punched through scrim 15 and thereafter to the underside 16 thereof. A latex coating 16-a is applied to underside of fabric 10 of which underside 16 is the bottom thereof providing an anchor for the punched in fibers 12. An additional backing of foam rubber 16-b or the like is adhesively fixed to the underside 1'6 and latex coat 16-a if such is desired.

Referring now to FIG. 2 a portion of fabric 10 is shown wherein is exposed the various layers which comprise the top of latex layer 16a, scrim 15 and its warp and fill

yarns

14 and 13 respectively, and the top of batt 11 after fibers 12 have been punched through. Scrim 15 in the portion exposed is illustrative of a nominal, preferred number of warp yarns 14, as shown, being thirty in number (the warp yarns running vertically in FIG. 2), and fill yarns 13, six in number. Thus a preferred scrim 15, which is herein referred to as a 30 x 6 scrim is in actuality one having, anywhere from 28 to 31 or 32 warp ends 14 and from 4 to 7 fill ends or picks 13. Hence it should be realized, for better comprehension of the inventive concepts herein presented, that an expression such as 30 x 6 when applied to the weave configuration of scrim 15, is intended to convey that these are nominal yarn numbers in the range above set forth.

FIG. 3 is illustrative of a corner-edge portion of scrim 15 in another embodiment, although the arrangement and type of woven yarns as well as the relationship of ends per unit length of warp to fill is retained as in the preferred embodiment. Scrim 15, as illustrated in FIG. 3, is an example of one woven on a shuttle-less machine such as the Sulzer loom above referred to, and a selvage edge 17 automatically is formed thereby. In forming selvage 17, however, fill yarns 13 are cut, as at A in FIG. 3, leaving ends 18 which are thereafter tucked in and through warp yarns 14 a short distance (see also FIG. 4). However, selvage 17 thus obtained had some disadvantages when scrim 15 was used in a needle punched carpet, chief among which was insufiicient yarn holding power during punching since the needles appeared to push some fill (and possibly some warp) yarns through to the carpet face, or at least yarn was visible thereat, hence an undesirable condition obtained. Means were therefore much sought after to secure cut ends 18 and to prevent yarn pull-out from the selvage. Thus an adhesive applied along the selvage edge helped, as did heat application to fuse the selvage. However, the preferred means discovered, and which is illustrated in FIG. 3, is to weave into scrim 15, at the edges, thereof, several (four are shown) monofilament warp yarns, as for example, round yarns 19, of sufficient denier (and therefore stiffness) to insure that fill yarns 13 are well crimped thereat. It has been found that a round polypropylene yarn 19 of about 400 to about 700 denier, preferably one of about 550 to about 600 denier (the ones shown in FIG. 3 are 565 denier) will cause ample crimping of fill yarns 13. Crimping of fill yarns 13 at the edge results in a secure, reinforced selvage 17 and supplies more than ample holding power thereto so that little or no scrim 15 yarn is pushed up into carpet 10 face yarn 12 thereby avoiding any unsightliness thereat. It is, of course obvious that the desired crimping will be promoted by closely spacing yarns 19 in selvage 17. Accordingly a new and novel, as well as useful, additional embodiment of inventive scrim 15 is presented to the textile and needle punching arts.

FIG. 4 illustrates the tucking in of cut ends 18 of fill yarns #13, being woven into scrim 15 through

warp yarns

19 and 14 to form new selvage 17.

In the preparation of a needle punched fabric such as carpet 10, as mentioned above, many problems were encountered in using a woven scrim therefor. A prior art scrim prepared from polypropylene ribbon-like yarns woven on conventional looms with twelve ends per inch in the warp and eight ends per inch in the fill performed generally satisfactorily. However, the same weave configuration, woven on the new, more economic shuttleless (Sulzer) machines, inexplicably presented heretofore unencountered problems. For example, as noted above, the scrim yarns such as yarns 13 being pushed through to the face of carpet resulting in an unsightly appearance, apparently caused by the needles holding some of the scrim yarns and forcing them up through the fibers of the batt resulting in clogged needles, increased machine down time and other operating difficulties.

It was quite unexpected, of course, to find that the heretofore apparently satisfactory weave configuration now performed unsatisfactorily when fabricated on the new, shuttle-less machines. This vexing problem remained unsolved, until the observation was made that while the same number of fill ribbons, eight, were retained in the new machine scrim, the coverage of these ribbons was increased ever so slightly because there was less twisting and folding thereof in weaving, in contrast to the older, shuttle machine weave. This increase in coverage by the fill yarns, though barely perceptible, was considered to be, at least in part, at fault. Other factors which contributed to the problem remained, including the fact that warp yam tension was somewhat higher with the new machines. Another contributing factor was the insufiiciently secured fill end 13 in the selvage above mentioned.

Another problem, not related to the means for weaving was that of excessive width reduction occurring during the later stages of the needle punching process, wherein the scrim, such as scrim 15, is subjected to heating and mechanical stresses which also tend to affect, adversely, the ability of the scrim to resist shrinking.

Width reduction occurs primarily because, in carpet manufacturing, the application of restraining forces to prevent such reduction, are not, as a practical matter, easily applied. Also, it is not usually feasible to compensate for width reduction by increasing the scrim Width before processing because of the Width limitations of commercial weaving machines. Nevertheless, width retention is of great importance to needle punched carpet manufacturers, since, with zero or acceptably low scrim width reduction, wider carpets can be manufactured and trimming of the fiber batt eliminated. This results in significant labor savings and other cost reductions including a saving in material, particularly if the finished product is cut into square tiles such as the 9 inch by 9 inch by 12 inch by 12' inch tiles now finding their way into the market for use in kitchens, bathrooms, patios etc.

It was found that width reduction particularly that due to the latex application step, i.e., heat shrinkage, in the carpet manufacturing process, was eliminated by annealing; however other factors are believed to be involved when total shrinkage, including shrinkage due to mechanical working, is to be eliminated, or at least minimized. A zero shrink scrim 15, therefore, is provided by this invention being one which has zero shrin filling yarns, i.e., less than 0.5% shrink at 270 R, which filling yarns were obtained by the novel step, as will be explained, of heat soaking, or annealing fill yarns 13 preferably prior to weaving, although it should be understood that such annealing may also be accomplished after weaving yet without resorting to a tentering process.

With respect to shrinkage due to mechanical working of the fabric as referred to hereinbefore, and henceforth to be referred to as mechanical shrink, it should be noted that this occurs because during weaving and punching fabric 15 is stretched and tensioned, especially in shuttle-less loom weaving. Also with prior art weave configurations, i.e., one having 24 warp yarns of ribbons 0.100 inch wide and 0.002 inch thick, there is a greater tendency for the ribbon to foldover on itself during weaving, therefore reducing the warp Crowdednoss N0. appreciably.

Consider therefore, the following example by way of 8 comparison of the above prior art scrim and the present invention and the relative tendencies of each warp yarn to foldover.

It has been observed that in a scrim weave of 12 ends per inch in the warp woven from ribbon yarns 0.100 inch wide by 0.002 inch thick and a CrOwdedness N0. of 1.20, (see table above) the ribbon nearly always fits itself into a confined lateral space by folding over 180 on itself to a fiat condition (effectively reducing the Crowd-edness No. to less than 1.00). By actual observation the warp ribbons in such a fabric vary in width according to the degree of folding: from 0.100 inch (no folding) to 0.030 inch.

On the other hand a sample of scrim 15 of this invention having 29 warp ribbons 14 per inch each of 0.048 inch in Width and 0.002 inch in thickness, thus having the same thickness as the prior art yarns, and manufactured in the same way and from the same polypropylene, has a Crowdedness N0. of 1.39 (see table above). However no appreciable foldover was observed, instead ribbons 14 of scrim 15 accommodate themselves in the limited lateral space by various means: bowing in spring-like fashion, as illustrated in FIG. 6, cocking at an angle to the plane of the fabric (FIG. 4), and edge crimping and distorting at points of crossing past adjacent warp ribbons 14 (FIGS. 5 and 6). Elsewhere, while lateral space is ample, i.e., above and below fill ribbons 13 warp yarns 14 are flat, in full, unfolded width, and usually, as shown in FIG. 7, even rise above (or fall below) fill yarns 13 a small distance h (see FIG. 7). Thus What should be evident from this is that scrim of this invention is relatively loosely woven, yet possessing good body (low sleaziness) and having a high degree of springiness. These characteristics combine and render fabric 15 quite unique, in that not only is width reduction caused by fill yarn shrinkage due to heat application eliminated, but width reduction caused by mechanical shrink is also eliminated. And, as discussed below, still further advantages accrue from use of the present invention and its novel weave configuration and selection of yarns therefor.

An acceptable fabric, whether manufactured by the needle punched process or otherwise, must have good lay-fiat characteristics. In order to insure good lay-flat in a carpet, the scrim or backing fabric must also have good lay-flat qualities, hence in using a woven scrim of plastic yarns, uneven tension in the warp direction i.e., a difference in tension from yarn to yarn, sometimes causes puckering (the presence in the fabric surface of waves and ripples, especially noticeable when the surface is viewed obliquely) which results in non-flatness of the scrim.

It was unexpectedly found that scrim 15 of this invention had superior flatness, and further, when used in a carpet gave a flat carpet. One reason for this is that the invention of scrim 1*5 possesses a lower relatively uniform, warp tension due to its loosely woven quality (see FIGS. 4 and 7) which relieves or eliminates the ill effects of tension differences, giving a flat appearing fabric surface as one result. In addition the number of warp ends 14 being increased to a high 1) Crowdedness No. distributes any individual non-uniformities in a more beneficial manner. It should also be noted that within the needle punch fabric industry, it has always been a working rule of thumb that to obtain good lay flat characteristics in a carpet one must have thin, smooth i.e., non-Woven, scrims. In contrast, scrim 15 of this invention is on the order of twice the thickness of usual scrims and quite rough in surface texture for reasons which will become more apparent from what follows hereinafter.

Still another problem which arises in needle punched carpet manufacturing is that of the batt of face fibers shifting after being deposited on the scrim and before the loaded scrim enters the needle battery of the needling machine. Batt shifting such as this results in non-uniform carpet thickness and non-uniform coloration thereof.

The ill effects of this problem were eliminated by the advent of scrim 15 of this invention since the surface thereof is sufficiently rough textured to more than adequately prevent shifting and slipping of batt 11. Scrim 15 is rough-textured because of, as clearly shown in FIGS. 4, 5, and 7, its relatively low warp tension and the presence of cocked, or bowed warp yarns 14 due to crowd ing i.e., high Crowdedness N0., and high resistance to foldover of the ribbons, (See FIG. 6.)

-An additional means for prevention of batt shifting which can be applied, and which is within the scope of the present invention is the surface treatment of scrim 15 with a lubricant as disclosed in Kennedy, C. T. application Ser. No. 453,478 filed May 5, 1965, and now Pat. No. 3,613,612. As described in that patent improved strength retention after tufting of a woven backing used in tufted carpets can be achieved by applying to the yarns prior to weaving, or to the backing prior to tufting, from 0.2 to 12% by weight of a suitable lubricant. Suitable lubricants include mineral oil, polyethylene glycol esters such as the stearate, laurate and oleate, high molecular weight polyglycols and various low molecular weight waxes. Such treatment can be applied to scrim 15 in the same manner and for the same reasons, i.e., strength retention after needling. However, a further benefit is realized in that the pesence of the lubricant on the

yarns

13 and 14 or the surface of scrim 15 tends to reduce electrostatic charge buildup which in turn may repel the batt rendering it more shiftable before punching. It is of course not to be assumed that a non-lubricated scrim is inapplicable to the invention herein, as it should be understood that scrim 15 in an unlubricated state is fully contemplated for the purposes of this invention.

Another problem, again related to the change from conventional to shuttle-less looms, was encountered in rolling a length of woven scrim fabric wherein a phenomenon known to the art as dog boning" occurred. Dog boning is, as the name implies, descriptive of a roll of scrim fabric having ends of significantly larger diameter than the middle portions and was found to occur because the selvages created by the Sulzer loom are thicker than the middle part due to tucked-in cut fill ends 18. Problems arise when the scrim fabric is removed from a roll since in the rolled condition yarn tensions are higher at the selvage edges which causes the scrim inner portions to loosen resulting in waves and ripples to give an unacceptable scrim fabric, one which will not lay flat.

Dog boning has been eliminated by use of the scrim fabric 15 of this invention because, as illustrated in FIG. 4, the over-all average thickness thereof is greater than prior art fabrics. The increased thickness, due to such factors as looser weave, low warp yarn tension, and the fact that high coverage in the warp (high Crowdedness N0. results in a floating warp (see FIG. 4 and warp yarns 14 therein.) It should be realized that while FIG. 4 is not necessarily to scale it is quite representative of the true relationship of the warp to fill yarn positions throughout scrim 15.

The above problems, and other hereinafter to be refered to, have been substantially overcome by the use of this invention, or, as earlier explained, have been so dealt with that any deleterious effects have been mitigated to an extent which, for that reason alone, the invention is believed to be a remarkable advance in the art of scrim fabrics for needle punched carpets, as well as the art of carpet making itself.

In its process aspects inventive scrim 15 is prepared from polyolefin ribbon yarns, preferably of isotactic polypropylene, which are oriented by stretching from 3 to 8 times, preferably about /2 times their original length. The denier of the warp yarns ranges from 250 to 700, preferably from 300 to 700. A particularly good working yarn denier is 500. The preferred yarns have a cross-sectional width ranging from 0.024 to about 0.140 and a thickness ranging from 0.001 to 0.003" and a most preferable ribbon is 0.048" x 0.002". Warp yarn shrinkage at 270 F. is within the range of from 0 to 10%, although 3% is most preferred. In general, yarns in the warp should be dimensionally selected in cross section so as to be sufficiently stiff to insure a high resistance to ribbon foldover thereby manifesting an ability to give a high degree of springiness to the scrim. Therefore, since stiffness is dependent upon the ribbon width to thickness ratio, a warp ribbon 14 having a ratio of from about 12 to 1 to about 35 to 1 should be selected. It will, of course, be appreciated that the final choice will be made taking into consideration the economics thereof. Hence, it has been found that to obtain the maximum number of desirable characteristics in a given scrim 15 consistent with low cost, use of the above preferred 0.048" x 0.002" (24 to 1 width to thickness ratio) ribbon for the warp yarns 14 results in an optimal selection.

Deniers of the fill yarns which can effectively be used range from 400 to about 1700, preferably from 700 to about 1250, while a particular denier of 1100 is most effectively accommodating. Isotactic polypropylene material for the fill yarn ribbons is also most preferred, their cross sectional width ranging from 0.040 to 0.150 inch, and their thickness from 0.001 to 0.003 inch, although the most preferred cross-sectional dimensions are, nominally 0.100 x 0.002 inch. Shrinkage of the fill yarns should be limited to from about zero to about 2.0% at 270 F., although a limit of about 0.5% is preferred and readily obtainable by means of the present invention. After orientation the filling yarn is wound on a spool or tube package, and prior to weaving is heat soaked, or annealed by heating at a temperature ranging from about 270 F. to about 325 F, with the tube immobile in an oven for periods ranging from at least one hour to a day or more, although a period of six to eight hours usually is preferred After heat soaking the yarn is set up on the loom and scrim 15 is prepared. Scrims having warp ends 14 in almost any number can be made although a range of about 20 to 45 ends per inch is most desirable. A most preferred number is nominally about 30 which, in practice, will range from 27 to about 32 ends per inch. Correspondingly, the fill yarns number from 4 to 10 per inch, although nominally 6 filling ends, or picks per inch encompassing a range of 5 to 7 is most preferred. Crowdedness Numbers preferably range from about 1.10 to about 1.55, the most preferred being about 1.39. The preferred fabric, as noted above, is woven on a shuttle-less machine for economic reasons. The problem of securing the fill ribbon at either selvage edge is accomplished by use of several ends of 550 to 600 denier, round monofilament polypropylene warp yarns 19 in selvage 17, closely spaced in order to crimp the ribbon fill yarns 13 to secure said cut ends 18 thereof after ends 18 are tucked back into the edge of scrim 15. These relatively stiffer polypropylene monofilaments not only adequately secure cut ends 18 but are so closely spaced, and the bead formed at the edge so narrow, that the diameter of large fabric rolls is no greater at either end than in the middle. Therefore dog boning is eliminated, although, as referred to above, the thickness of the fabric itself gives a unifom diameter when rolled, which in turn, is, in part, a result of crowding, .(high Crowdedness N0.) of warp ribbons 14, coupled with weaving thereof with little or no folding, due to the stiffness as determined by the prefered width to thickness ratio of 12 to 1 or higher and low tension therein to give a relatively overall thick, rough-textured scrim fabric 15.

Scrim 15 and fabric 10 containing scrim 15 can be processed in substantially any length, width or thickness depending upon the apparatus being employed. As a practical matter widths of twelve to fifteen feet are most commonly encountered in the trade. Wider scrims however, can be made and are supplied to the needle punch 1 1 fabricator and are within the scope of the present invention.

Referring now to FIGS. 5 and 6 there is illustrated a portion of fabric 15 inboard of the edges. FIG. 5 indicates the effect of crowding the warp yarns, and is a presentation, substantially to scale, of a nominal 30 x 60 scrim 15. The filling is somewhat open" since fill yarns 13 are spaced apart, and lies quite flat, i.e., substantially uncrimped, although an occasional one may have a slight twist as indicated by portion 13a in FIG. 7.

FIG. 6 is a representation of the manner in which warp yarns 14 crowd in, cock or bow when, in scrim 15, they pass over and under fill yarns 13. Fill yarn 13 is also shown and it should be noted that it is uncrimped even though the warp, as shown, has a high (1.39) Crowdedness Number. Reference to FIG. 4 even more clearly illustrates the lack of crimping in fill yarns 13 (except, of course at selvage 17 where special means is provided to insure crimping). However, elsewhere throughout fabric 15 crimping in the fill direction is almost nonexistent and it has been found not only unnecessary, but in fact to be undesirable, in contrast to prior art scrims wherein the warp, when the number of yarn ends were increased, it was for the purpose of insuring fill yarn crimp. In the prior art fill crimping is considered desirable, because in reducing width reduction caused by shrinkage of fill yarns, a crimped fill yarn was understood to provide increased length, or slack, in the filling yarns. This expediency has been found totally unnecessary by use of the inventive scrim 15 hereof, since fill yarns 13 are treated in a novel and inventive manner whereby, regardless of the heat producing stresses applied later on in manufacturing, fabric 15 is substantially non-shrinking.

As referred to earlier in this specifiction, an advantage of the invention embodied in scrim 15 comprising a crowded warp and an uncrimped fill is the ability thereof to resist tendencies to suffer adversely from objectionable width reduction when subjected to mechanical working stresses, i.e., mechanical shrink, whereby a tendency of the fabric to neck-down or draw in when placed under warp-wise tension occurs. Scrim 15, because of its high Crowdedness No. combined with the fact that it is relatively loosely woven and possessing springiness will, when stretched warp-wise, tend to uncock, unbow or undistort its warp yarn 14, especially at the interweave sections shown in FIG. 6, thereby substantially preventing, or more precisely, successfully opposing any tendency of the overall fabric to suffer width reduction due to neck down.

Accordingly what has also been developed, invented and described herein is a novel woven fabric useful as a scrim in needle punched fabrics, which comprises warp yarns of synthetic plastic, loosely woven in a fabric so as to be highly crowded therein with a substantially uncrimped fill, said fill being substantially open.

The following examples are therefore presented to illustrate several of the various possible applications for the present invention.

EXAMPLE I A plain weave fabric was woven on a shuttle-less loom from polyethylene glycol ester type lubricated polypropylene ribbon yarns. The yarns were oriented by stretching 5.5 times their original length and the woven fabric contained relatively stiff, 29 ends per inch of 500 denier ribbon, 0.47" x 0.002 in cross section and a warp Crowdedness No. of 1.39. The fill contained 6 ends per inch of 1100 denier ribbon having a cross section of 0.100 X 0.002", said filling yarn being earlier subjected to a heat soak at a temperature of 290 F. for 24 hours, while immobilized, to give a 0.0% 0.l%) shrinkage at 270 F. The selvages of the fabric were tucked back and contained 4 ends of 565 denier round monofilament yarns of polypropylene at each edge for securing the cut fill yarn ends. Overall fabric width was 152.9". This fabric was used as the scrim in a typical needle punch operation.

The batt of face fibers exhibited no slippage so that carpet appearance and thickness were uniform. Punching through of scrim yarn which was visible on the face of the carpet was minimal and acceptable. The fabric width reduction was very slight, to 152" after needling, latexing (a process wherein a liquid latex is applied to the bottom side of the carpet) and drying on rolls heated to 285 F. The lay-fiat of the carpet was good. The carpet grab strength was acceptable, being 124 lbs. in the fill direction and lbs. in the warp direction.

EXAMPLE II The scrim fabric of Example I was processed in a different style carpet in a series between sections of a conventional scrim of 12 x 8 ribbon-to-ribbon construction of 0.100" x 0.002 cross section (50 to 1 width to thickness ratio) which had been heat set by tentering. Both scrims were carried through identical processes to make a needle punched carpet. The Example I fabric suffered only a two inch width reduction whereas the conventional scrim exceeded five inches in width reduction. Carpet from Example I scrim fabric also exhibited a superior flatness and fewer polyproplyene ribbon yarns were observed to be visible in the face pile of the carpet. The latter advantage and improvement appears to be the result of easier penetration by the needles into the scrim of Example I resulting in less fracturing of the ribbons and therefore less pushing through thereof into the carpet face. The easier penetration results from a more loosely woven, Example I scrim fabric, as demonstrated by the low values for warp and fill pull out given in Table I here following, and also in the springlike quality inherent therein due to the floating yarn characteristic illustrated in FIG. 4. Also, the fill being crimpless, permits easy side to side warp yarn movement and the ribbons thereof collapse or move somewhat like venetian blind, slats, manifesting springiness.

TABLE I XAM. I Comparison of scrim fabrics for needle-punch carpets Present Prior art scrim invention Scrim fabric Warp Fill Warp Fill Method of weaving Shuttle-less Conventional shuttle loom loom fabric Construction, nominal W x F 30 x 6 12 x 8 Construction, actual W x F 29 x 6 12 x 8 Fabric wt., oz./sq. yd 2.6 2.8 Ribbon yarn cross-section: l

Warp, inches 0.048 x 0.002 0.100 x 0.002

Fill, inches--. 0.100 x 0.002 0.100 x 0.002 Fabric thickness, 0.030 0.015 Fabric shrinkage, in

minutes:

At 270 F., percent 3. 1 0.0 2. 2 2. 3

At 290 F., percent 5. 6 1. 3 5.6 6.4 Fabric grab strength: 3

Lb. break 94 51 127 57 Percent bk. elong 26 24 24 15 Fabric yarn pull-out, gram 13 9 224 49 Fabric width, inches 153 152 Finished carpet fabric: 6

Width, inches .1 151 147 Carpet grab str.,1bs-- 124 9 126 Carpet wt., oz./sq. yd 19.3 19.4

1 Dimenslonally and theoretically the 12 x 8 prior scrim appears to have a crowded warp and a 1.20 Crowdedness N0. However in practice due to the high percentage of warp yarn foldover and doubling up, the efiecttve Crowdedness No. Was observed to be at most about 1.0. Hence this scrim should not be considered as having a crowded warp.

2 Scrim thickness measured as the separation of two steel plates, 4" x 4 and $1 a thick. Scrim fabric is sandwiched between, with only the pressure of the weight of the top plate.

3 Standard textile test: 4 by 6 piece pulled at rate of 12" min. in long direction; 3 between test jaws; width of jaws 1 inch.

4 Pull-out is a measure of sleaziness of the fabric. The value is the force in grams to pull out one 3" long ribbon strand from the fabric. Test was run on both warp and fill.

Finished carpet; after scrim is needle-punched on both sides and latex applied to one side, with exposure to 285 F. heat for curing the latex.

EXAMPLE III A scrim fabric differing from the scrim of Example I in that there were 45 ends per inch in the warp and 9 fill ribbon yarn ends per inch was made with ribbons 0.034" x 0.0015" warp (width to thickness ratio about 22). The warp ribbon displayed no foldover on observation after weaving in the confinement of the fabric weave.

EXAMPLE IV A series of scrim fabrics similar to Example I scrim were prepared as follows: each scrim fabric had nominally the same number of warp ends per inch (30), however one sample had 6 fill ends per inch, the second sample had fill ends and the third sample had 4 fill ends. As in Example I, the six fill ends per inch scrim performed well, the five fill ends per inch scrim fabric also performed satisfactory through needle punching. The four fill end per inch fabric was considered of border line quality mainly because of its sleaziness which gave some difficulty in handling the bare scrim fabric, otherwise it appeared to perform well.

EXAMPLE V To prepare low or zero shrink filling yarn, the following steps were performed. Several filling yarn tube packages of 1100 denier polypropylene ribbon were exposed i.e., heat soaked, or annealed by heating, to 290 F. air temperature for 24 hours. Each tube package contained eight pounds of filling yarn on a 3" diameter core wound to an 8 /2" outside diameter and 6 in length. The fill yarn thus treated was tested and found to have 0.25% shrinkage of 270 F. after minutes in an air circulating oven. This yarn was thereafter used to make a scrim fabric of 0.0% 0.1%) shrinkage in the fill direction.

EXAMPLE VI A scrim fabric having a weave configuration of 24 warp ends per inch and 6 filling picks was prepared on a shuttle-less loom from warp ribbons nominally 0.050" x 0.002" in cross section (25 to 1 width to thickness ratio) and 0.100" x 0.002" in cross section fill ribbons. The warp Crowdedness N0. was 1.20. The fill ribbons were run over a hot roll prior to being wound on a tube package prior to weaving, and then the fill yarn containing tube package was heated in a horizontal flow forced air oven with the tube positioned therein on its long, horizontal axis for a period of from 4 to 6 hours at an air temperature of 290 F. The fabric was similar in appearance with respect to yarn foldover and springiness to the fabric of Example I and when used in a needle punched carpet resulted in a carpet of similar appearance. The fabric in this example was unlubricated and had a selvage prepared by heat sealing the edges thereof.

The invention herein above described and alluded to is, of course, understood not to be limited solely to the embodiments shown, since many modifications can be made by skilled artisans without departing from its spirit and scope. For example the (nominally) x 6 fabric, is a zero shrink, Sulzer or shuttle-less loom fabrc with zero or a negligible amount of crimp in the fill yarns. It is believed that this feature as noted hereinabove, is significant and contributes substantially to the wide spread acceptance of his inventive scrim fabric by the needle punched carpet industry, at least as of the present time based on experimental use thereof by the industry. It is known for example that non-crimp in the fill yarns would appear to run contrary to the widely held theory that any increase in number of warp ends would decrease width reduction in the fabric. This theory states that more warp ends per inch, i.e., greater crowding (increased Crowdea'ness N0.) means more crimp in the fill, thus, greater length of the fill yarns in a given width of fabric. However, as noted elsewhere herein, with the particular fabric of this invention, increasing the number of warp yarns to thereby crowd the warp with extra yarns, did not increase crimp in the fill yarns. Further, yarn tenacity is not decreased in the annealing treatment. In fact some tests indicate that there may even be a slight increase in tenacity. Yarn strength is also an important property in imparting strength to the final carpet and is one of the chief functions of the scrim itself in needle punched carpeting. Therefore, what is sought to be protected by Letters Patent of the United States should not be limited except as indicated by the subtending claims.

What is claimed is:

1. A needle-punched fabric comprising a scrim woven of polyolefin warp and fill yarns, said warp yarns being fiat ribbons of substantially rectangular cross section and having a Crowdedness Number of at least 1.10, said fill yarns being flat ribbons of substantially rectangular cross section and having a Crowdedness Number of less than 1.0, and said fill yarns being substantially uncrimped in said scrim.

2. The fabric of claim 1 wherein the polyolefin is polypropylene.

3. The fabric of claim 1 wherein the filling yarns have been annealed prior to weaving in said scrim.

4. The fabric of claim 1 wherein the warp yarns have a denier in the range of from 200 to about 700.

5. The fabric of claim 1 wherein the filling yarns have a denier in the range of from 400 to about 1700.

6. The fabric of claim 3 wherein the filling yarns have been annealed by heating said yarns to a temperature of from 270 F. to about 325 F.

7. The fabric of claim 3 wherein the filling yarns have been annealed for at least one hour.

8. The fabric of claim 1 wherein the Warp yarns have a clross sectional width to thickness ratio of at least 12 to 9. The fabric of claim 8 wherein the ratio is in the range of from 12 to 1 to about 35 to 1.

10. The fabric of claim 3 wherein the fill yarns have been annealed to less than 3.0% shrinkage at 270 F.

11. The fabric of claim 3 wherein the fill yarns of said scrim have been annealed while wound on a tube package and immobile.

12. The fabric of claim 3 wherein the fill yarns have been run over a hot roll and thereafter wound on a tube package prior to weaving into said scrim.

. 13. The fabric of claim 1 wherein the ratio of ends per inch in the warp to that of the fill is at least 3 to 1.

14. The fabric of claim 1 wherein the ratio of ends per inch in the warp to that in the fill is in the range of from 3 to 1 to about 10 to 1.

15. The fabric of claim 1 wherein said scrim includes selvages comprising; at least one warp-wise monofilament yarn having a substantially round cross section and closely spaced from said warp.

References Cited UNITED STATES PATENTS 1,922,739 8/1933 Lees 161-71 2,951,277 9/1960 Youngs 161-91 X 3,058,194 10/ 1962 Havner 16171 3,439,865 4/1969 Port et a1. 16l--71 X 3,443,541 5/1969 Chopra 161-65 3,542,632 11/ 1970 Eickhoff 2872.2 X

FOREIGN PATENTS 1,510,153 12/1967 France 139-422 R ROBERT F. BURNETT, Primary Examiner R. O. LINKER, 1a., Assistant Examiner US Cl. X.R.