US 3819462 A
A tufted carpet primary backing made up of a nonwoven base web formed from low cost short fine fibers (e.g. cotton) and longer coarse fibers (e.g. 4 inch, 15 denier synthetic fibers) bonded together. The nonwoven is needled and reinforced by the addition of other strength imparting components, such as threads or continuous filaments stitched on the web in a tricot pattern.
Description (OCR text may contain errors)
' 0 United States Patent 1191 1111 3,819,462 Starr et al. June 25, 1974 [5 PRIMARY BACKING FOR TUFTED 3,309,260 3/1967 BOCSB 161/150 3,325,323 6/1967 Forkner 161/67 CARPETS 3,329,556 7/1967 McFa11s et a1. 161/170 Inventors: John R. Starr, Belmo t; Arthur R 3,394,043 7/1968 Parlin et a1. 161/67 Drennan, Brighton, both of Mass. 3,501,369 3/1970 Drelich et a1. 161/170 73 I Y Asslgnee 5 ncorporated New ork Primary Examiner-William J. Van Balen Attorney, Agent, or Firm-Burns, Doane, Swecker &  Filed: Oct. 12, 1970 Mathis  App]. No.: 79,762
 ABSTRACT 52 us. 01 161/62, 156/72, 156/148, A tufted camet p y backing made p of a nonwo- 161/67, 161/150, 161/157, 161/170 ven base web formed from low cost short fine fibers  Int. Cl. D03d 27/00, D04h 11/00 co n) and longer coarse fibers -g- 4 inch, 15  Field of Sea h 161/62, 67, 150, 157, 170; denier synthetic fibers) bonded together. The nonwo- 15 /72 14 ven is needled and reinforced by the addition of other strength imparting components, such as threads or  References Cited continuous filaments stitched on the web in a tricot UNITED STATES PATENTS 2,574,s49 11/1951 Talalay 161/157 9 Claims, 4 Drawing Figures PATl-lNTEnJuuzswu HGI SHORT FINE STAPLE FIBERS LONG COARSE v SYNTHETIC FIBERS I NON-WOVEN SUITABLEI I FOR BONDING I LliiQEfiJ NEEDLED NON -WOVEN 26 F I ST ITEHIIN G I REINFORCED PRIMARY BACKING CALENDERED PRIMARY BACKING FIGZ 1 PRIMARY BACKING FOR TUFT ED CARPETS BACKGROUND OF THE INVENTION This invention relates to nonwoven fabrics and particularly to tufted carpet primary backings and methods of producing the same.
Much of the carpeting that is made today is fabricated by tufting procedures. A flat backing fabric of suitable width, typically about 9 to 18 feet, is fed longitudinally through a tufting zone. In this zone pile carrying tufting needles disposed across the entire width of the primary backing are caused to penetrate the backing so as to dispose loops of pile yarn on the bottom side thereof. These loops may be left uncut or they may be cut to provide the ultimate pile face of the carpet.
After tufting, the material usually is subjected to the application of an adhesive on the back of the primary backing so as to anchor the pile yarns more firmly in place. Piece dyeing or pile face printing operations may be carried out on the material at this stage also. Finally, in order to enhance the dimensional stability of the pile fabric, a secondary .backing may be adhered to the back face of the primary backing.
The present invention is concerned primarily with primary backing materials for use in tufted carpets. Although the backing forms an inconspicuous part of a carpet as the user normally sees it on the floor, such backing is from an engineering point of view a critical component both during fabrication operations and while the fabric is in use.
The mechanical abuse to which a primary backing is subjected during tufting is extraordinary. The tufting needles are relatively large and closely spaced across the width of the primary backing as the latter is fed through the tufting machine. As these needles are moved through the backing to insert the pile yarn loops, the material of the backing in the needle paths must either shift or break in order to provide the openings for the needles. Moreover, during the time when the fabric is being so weakened, it is also held under substantial tension in order that the desired linearity of movement of the fabric through the machine may be obtained so as to assure regularity in the positioning of the pile loops. The net result is a very strong tendency for the primary backing to rupture during tufting.
The tufting operation imposes still another mechanical requirement upon the primary backing material. Not only must it withstand the extraordinary loads and strains occasioned by the penetration of the tufting needles, it must also have a capacity for closing the needle holes sufficiently to cause the primary backing material adjacent the holes to engage the pile yarns left by the needles and hold the pile loops in place.
After tufting, still other loading patterns are imposed upon the primary backing. Ordinarily the processing associated with adhesive application, piece dyeing, etc., is carried out by moving the fabric linearly through a treatment zone under tension; and the fabric must of course be able to withstand the tension loads applied during these procedures. Moreover, since the fabric pulling forces applied to the wide widths of fabric being treated rarely will be uniformly distributed across the width of the material, the fabric must have a degree of crosswire rigidity sufficient to prevent substantial bowing or skewing of the fabric as it is moved through the processing zones.
During installation of the carpet, high loads again may be applied in various directions in attempts to get the fabric properly aligned on the floor, and the fabric may be cut in various directions in making it conform to the space where it is being installed. Hence, additional opportunities for tearing the fabric are provided and there is also a possible raveling problem unless the backing structure has been designed so as to have a capacity for preventing raveling.
During use of the carpet, the backing must hold the pile in place throughout the life of the carpet, and the primary backing must play a role in this task. Additionally the primary backing must be inconspicuous in the sense that it should not be allowed to grin through to distract from the appearance of the pile surface. Finally, the primary backing should not contribute to the flammability of the fabric as a whole or to any tendency the fabric may have to deteriorate through rot or mildew. In some instances the primary backing may actually be designed to militate against such undesirable effects through proper treatments.
In view of the many complex engineering criteria associated with primary backings, it is not surprising that only a few materials have proved really useful in large scale commercial operations. A brief review of these will demonstrate the state of the practical art prior to the present invention.
In the days before tufting was used for the production of carpets as such, this process was employed to some extent in the production of scatter rugs and the like. For such operations it was customary to use woven cotton fabric as the-backing. For scatter rug applications cotton duck still is a widely used backing material, but it has proved unacceptable for the carpet application. Lack of dimensional stability severely limits the utility of backing structures made by weaving cotton yarns, and cotton was prior to the present invention generally considered unsuitable as the base material for a primary backing to be used in the fabrication of tufted carpets.
In the early days of the tufted carpet industry, woven jute was used almost exclusively. Woven jute fabrics in the weight range of 8 to 12 ounces per square yard had the strength and stability characteristics required for the production of many types of tufted carpeting and such jute fabrics have been used as primary backings for millions of square yards of tufted carpet.
, Although jute is still widely used for primary backings, a number of practical problems are associated with this material. The woven jute comes from the Far East and carpet producers in the United States have encountered supply shortages and unpredictable price variations which proved to be serious hardships. Additionally, the jute has a number of mechanical deficiencies. The coarse jute yarns are crude mechanical structures in the sense that they vary enormously along their lengths, being characterized by thick and thin zones of varying mechanical properties. As a consequence fabric failures of an unpredictable nature have occurred often enough during the processing of jute backed tufted carpets to be troublesome in ordinary mill operations where the maintenance of clearly defined production schedules is of substantial importance. The coarse jute yarns also give a primary backing formed from such material a tendency to dispose the pile loops in irregular patterns. This phenomenon often is referred to in terms of needle deflection. For example, on one stroke of a tufting needle, the needle point may strike a jute yarn so as to dispose the pile loop on the left side of that jute yarn while on the next stroke it may strike the yarn in such a way as to dispose the loop on the right side of the jute yarn. As the fabric closes around these loops, further distortion appears so that the two successive loops will not be aligned longitudinally along the fabric. Similar effects prevent the attainment of perfect crosswise loop alignment, and pile carpets tufted on jute backings typically are characterized by irregularities in the rows of pile loops.
In an effort to obviate some of these problems, the industry has turned increasingly in recent years to synthetics. The most wisely used synthetic primary backings have been formed from polyolefin materials, with polypropylene generally being the most highly regarded material at the present time.
One type of polypropylene primary backing that has enjoyed considerable success is a woven material employing ribbons as the warp yarns and employing either ribbons or multifilament yarns as the weft yarns of the woven construction. These primary backings have many desirable qualities. However, since they are based upon specially fabricated ribbons, price and supply problems still are associated with such materials. Moreover, their reliance upon discreet yarn-like components for giving the overall woven backing fabric its mechanical properties presents some difficulties where fine gauge tufted fabrics are involved. There is little structural component shifting in the woven ribbon polypropylene backing during tufting; and where the spacing between needle penetrations becomes quite small, as in the fine gauge high pile density carpets, the structural components of the woven backing may be broken by the needles to an objectionable degree and the backing fabric may be left with insufficient strength.
Another type of polypropylene primary backing that has achieved wide acceptance in the tufted carpet industry is a nonwoven fabric. One such fabric is a continuous filament, spunbonded product sold by E. I. du- Pont de Nemours and Co. Inc. under the trademark Typar." Another such fabric is a staple fiber nonwoven fabric manufactured by Phillips Fibers Division of Phillips Petroleum Company and sold under the trademark Loktuft. The latter is made by garnetting polypropylene fibers of approximately 5 denier and 4 to 4 /2 inch staple length, crosslapping the garnetted webs and adding longitudinally extending cotton or rayon yarns as reinforcing components. The composite then is subjected to needling and is lightly heat fused.
Both of these nonwoven polypropylene products have desirable mechanical properties but both have disadvantages associated with the polypropylene material. The polypropylene material does not readily accept dye and thus can grin through in carpets having low face yarn content. Although some techniques have been devised to deal with the grinning problem, these techniques in turn have disadvantages in that they impose color coordination problems on mill production operations.
In spite of the great volume of primary backing required by the tufted carpet industry and the economic importance of a steady supply at low cost, almost no progress had been made prior to the present invention toward utilization of low cost fibers of the types normally associated with the production of other types of textiles. In particular, designers of primary backings have steered away from cotton fibers even though enormous quantities of cotton fibers are readily available at very attractive prices. For example, virgin cottons having length and/or color characteristics not especially desired for ordinary textile yarns and cotton and/or cotton-synthetic blend mill wastes from textile yarn making operations are regularly available on a continuing basis and at low cost in the United States.
References to the possibility of using cotton fibers in primary backings have of course appeared in patents, but no practical approach to the production of a backing from cotton fibers which would have satisfactory mechanical properties had been made prior to the present invention. In fact, the shortness and thinness qualities of cotton fibers have made it quite difficult to envision a practical cotton fiber based composite which would withstand the large strains and high stresses occasioned during tufting machine needle penetrations. A typical cotton fiber may have a length on the order of /2 to 1V2 inches and a width corresponding to a denier of about 1. When one envisions an assembly of such fine short fibers being repeatedly penetrated by a bank of closely spaced tufting needles of substantial size, the severity of the problem becomes evident.
SUMMARY OF THE INVENTION Accordingly, it is a general object of this invention to provide a novel nonwoven fabric product made largely from such readily available textile grade staple fibers as cotton, which product may serve as a primary backing for tufted carpets. This backing not only has attractive cost and performance characteristics but also is amenable to dyeing, rot and mildew resistance treatments, and flame retardancy treatments.
Although cotton fibers and the types of blends of cotton and other fibers used in textile yarn making are preferred for use as a basic material for the fabrics of the invention, this fiber content may in a broader aspect of the invention be viewed as the fine fiber content, by which is meant staple fibers having deniers of about three or less. For example, low denier rayons or blends having these characteristics may at times be available at attractive prices and could be used if the basic principles of the invention were applied in processing such materials.
In accordance with the present invention the fine fibers are combined with smaller numbers of longer coarser fibers to form a nonwoven base web. Although air laid webs can be employed, normally it is preferable that the fine and coarse fiber contents be carded together and that the card webs be crosslapped to provide the nonwoven base material.
For the coarse fiber content, synthetic fibers of at least 6 denier and having staple lengths at least as great as 4 inches are suitable, with somewhat coarser (e.g. 10 to 20 denier) fibers being preferred ordinarily. The coarse fibers may be formed from various materials. From the standpoint of cost, polyester fibers are particularly attractive, but good results also have been obtained using polypropylene fibers. From the standpoint of flame retardancy, glass fibers and modacrylic fibers have outstanding properties, and these may be used if desired.
Some bonding together of the fibers in the web is required. In some instances the necessary bonding effects can be obtained by using coarse fibers of thermoplastic material or having thermoplastic sheaths and heating the web under pressure. In most instances, however, optimum bonding can best be achieved through the use of added bonding agents. Under either approach, what is most desirable is a bonding together of the individual fibers of the fiber network at a sufficient number of the fiber crossing points to give the web structural strength. In general, the bond strengths should be substantially less than the strengths of the fibers employed so that under load the bonds will break prior to rupture of the fibers. With the bonds broken in a given area, fiber migration to accommodate the imposed load occurs and the tendency toward propagation of a failure to other zones of the fiber network is minimized.
The combination of the fine and coarse fibers in the nonwoven web has a remarkable effect upon the response of the web to the stresses and strains imposed during tufting. A web composed solely of fine short fibers is severely damaged during tufting because these fibers have insufficient mobility within the web to yield. under the actions of the needles and insufficient strength to withstand the loads imposed upon them. However, when a web of the same overall weight additionally includes longer coarse fibers these problems are minimized. The long coarse fibers are individually quite strong, so that they do not break readily under direct impact from a tufting needle but tend rather to be displaced. The relatively long lengths of these fibers moreover make such displacements possible without disrupting too many of the bonds between an individual long coarse fiber and other fibers in the web. As these long fibers undergo incremental displacement, therefore, they carry short fine fiber segments with them. As a result fiber mobility within the web is enhanced and fiber breakage is minimized.
Although the fine and coarse fiber nonwoven provides a component which is compatible in an engineering sense with the tufting operation, it normally will be further necessary to employ still other strength imparting techniques in order to achieve a primary carpet backing of fully adequate properties. For example, needling the web serves to interlock the fibers more effectively and give the web a significantly enhanced integrity or strength, and needling normally will be employed in connection with the crosslapped card webs preferred for use in the practice of this invention.
Additionally, it normally will be found desirable to include in the backing structural components in continuous strand form. Yarns or continuous synthetic filaments may be run in parallel sheets extending along the longitudinal direction of the material or woven scrims may be combined with the nonwoven.
Still another technique that has proved especially convenient and effective is stitching added yarns into the nonwoven with these added yarns running generally in the lengthwise and/or crosswise direction of the material or being disposed in a tricot stitch pattern along the length of the material.
THE DRAWINGS A fuller understanding of these and other features and advantages of the invention will be gained from a consideration of the following detailed descriptions with reference to the accompanying drawings in which:
FIG. 1 is a schematic flow chart illustrating the formation of a primary backing according to the present invention;
FIG. 2 is an enlarged schematic view of a portion of a non-woven base web utilized in the primary backing formed according to FIG. 1;
FIG. 3 is a cross-sectional view of a tufted carpet embodying a primary backing formed according to FIG. 1; and
FIG. 4 is a schematic illustration of needle overlap in a tufting zone.
DETAILED DESCRIPTION FIG. 1 indicates at 10 a supply of short fine fibers of a type not heretofore considered desirable for use as a major component of primary backings. These fibers may have widths corresponding to deniers of up to about three, and lengths of up to about 3 inches. However, fibers having widths corresponding to deniers of about three quarters to about 1 /2, and lengths of about /2 to 1V2 inches, are of greatest importance and will normally be used.
The preferred fine fiber is cotton. Virgin cottons having staple lengths of about 1 inch or less are widely available at attractive prices and are well suited for use in the present invention. Additionally, mill wastes may be especially attractive from the standpoint of availability and cost. For example, in the production of combed cotton and cotton/polyester yarns, quantities of comber noils containing cotton fibers are produced. These and other mill wastes from textile yarn production operations are well suited for use in the invention. Still other artificial cellulosic fibers may be used either alone or in combination with other short fine fibers for the fine fiber content 10.
FIG. 1 additionally indicates at 12 a supply of long coarse synthetic fibers. These may be formed from polyolefin such as polypropylene, polyesters such as polyethylene terephthalata, glass, modacrylics and other materials. In any case these fibers should have lengths of at least about 4 inches and deniers greater than about 6. Fibers having deniers in the range of from about 10 to about 20 are especially preferred.
The fine fiber content 10 and the coarse fiber content 12 are combined in the proportions of about 25 to by weight of the fine fibers and 75 to 25% by weight of the coarse fibers. Normally it will be preferred to card the fine fibers and the coarse fibers together to produce card webs containing the mixture and then to crosslap the card webs so as to build up a composite structure having a weight of at least about 4 ounces per square yard. Such a nonwoven base web 14 is illustrated schematically in FIG. 2 where the fine fibers are indicated at 16 and the coarse fibers are indicated at 18. It will be appreciated, however, that air laid webs containing the mixture of fine and coarse fibers may be employed, if desired.
In a preferred example, the base web 14 consisted of 60% by weight of virgin cotton fibers of the strict low middling, lightly spotted, classification having a staple length of about 1 inch and 40% by weight of 15 denier second quality polyester staple fibers about 4 inches long. These fibers were carded together and the card webs crosslapped to produce a base web of about 4.7 ounces per square yard.
Some bonding together of the fibers in the web 14 is required. Therefore, as indicated at 20 in FIG. 1, the
nonwoven must be rendered suitable for such bondings. Where the coarse fibers 18 are in the form of thermoplastic materials or have themoplastic sheaths, the necessary bonding effects can be obtained through heating the web under pressure, normally at a later stage in the preparation of the primary backing as hereinafter described. Generally, however, optimum bonding can be achieved through the addition of bonding agents. For example, in FIG. 1 the addition of a bonding agent or binder 21 to the nonwoven base web 14 is indicated. Polyethylene powder such as Microthene FN 500 in an amount equal to approximately 10% of the weight of the base web 14 has proved to be an adequate bonding agent. As in the case of bonding by utilizing the thermoplastic properties of the fibers themselves, actual fiber bonding with the powdering technique is accomplished at a later stage in the preparation of the backing'by activating the bonding agent 21.
It will be readily apparent that still other bonding techniques may be utilized. Such techniques may include the addition of polymer lattices and polymer solutions by saturating the web, or the coating of the fibers with adhesive materials.
Whatever technique is employed, the fine and coarser fibers should ultimately be bonded together at a sufficient number of fiber crossing points to impart structural strength to the base web 14. In order to facilitate fiber migration to accommodate imposed load and to minimize the propagation of a failure to other zones in the fiber network, the bond strength should be substantially less than the strength of the fibers employed in the network. Thus, bond breakage and fiber slippage, rather than fiber rupture, will occur during tufting. In an ideal situation, the binder would be located between fibers at crossings to provide a more flexible joint and to avoid plugging of open spaces between the fibers. Moreover, this binder location minimizes binder waste on fiber surfaces where the binding function is unimportant. Lubricity in the binder for'the purpose of minimizing heat buildup on the needle during tufting is also desirable.
Additional treatments for enhancing the strength of the web normally are required to produce a primary carpet backing of fully adequate properties. As indicated in FIG. 1 at 22, mechanical treatment of the nonwoven in the form needling may be undertaken. Needling densifies and increases the strength of the web by pulling its surface fibers through the web as the needles move vertically through the web. The fibers are thus locked together in a three dimensional array with the interlocked fibers serving to significantly enhance the integrity or strength of the web. Normally, such a needling technique will be employed in connection with crosslapped card webs preferred for use in the practice of the present invention.
Conventional needling techniques may be employed and in the case of 60/40 cotton polyester base web earlier discussed,.the carded crosslapped web was needle tacked at 800 rpm on a Hunter tacking loom.
The needling density, i.e. the penetrations per square inch, may be varied in accordance with the fiber content of the base web. It may be expected that needling is more beneficial to the webs containing higher contents of coarse fibers by reason of the fact that the coarser fiber has additionally sufficient length to be pulled down into the web. In connection with the needling operation, it may sometimes be desirable to lubri- 8 cate the web prior to needling in order to minimize the tendency of cotton in the web to pill.
Other useful mechanical treatment of the nonwoven is the addition of reinforcing members to provide a reinforced primary backing as indicated at 24 in FIG. 1. These reinforcing members may be provided by stitch bonding the nonwoven, with added continuous filament or spun yarns or threads disposed in chain stitch reinforcing patterns running generally in the lengthwise and/or crosswise direction of the material or being disposed in tricot stitch pattern along the length of the material. The stitching technique of reinforcing is indicated at 26 in FIG. 1. Acceptable results have been obtained with tricot pattern stitching of the preferred cotton-polyester web referred to above at a stitch length of 3.2 millimeters using 0.25 0.3 ounces per square yard of deniercontinuous multifilament polyester thread. A Maliwatt machine available from Crompton & Knowles Malimo, Inc., Worcester, Massachusetts, was used for this stitch bonding. The main function of this reinforcement is to provide tensile and tear strength particularly after tufting, with the bonded nonwoven base web serving to provide a uniform matrix to tuft into and to lock the tuft in place.
When powder bonding techniques are employed to produce the desirable bonds at the fiber crossing points, the powder addition portion of these techniques should be instituted prior to stitching insofar as the stitched web may be too densified for the powder to adequately penetrate.
As indicated at 28 the reinforcing members may be supplied in the form of a woven scrim, or yarns, continuous synthetic filament tows, spun bonded webs, and- /or split film ribbons may alternatively or additionally be run in parallel sheets extending along the longitudinal and/or transverse direction of the material.
With reference to FIG. 1 at 30, it will be seen that normally the reinforced primary backing will be calendered utilizing conventional techniques. Through calendering the nonwoven the web tensile strength may be increased. It is at this stage that the earlier noted fiber bonding normally will take place through heat and pressure activating the bonding agent 21 if utilized or causing bonding of thermoplastic fibers, if employed.
In FIG. 3 a tufted pile carpet embodying a finished primary backing constructed in accordance with the procedures outlined in the flow diagram of FIG. 1 is illustrated in cross-section. In this cross-sectional view the primary backing is identified as 32. It will be appreciated that the primary backing has been tufted using conventional tufting processes whereby tufting needles are caused to penetrate the backing. The needles carry pile yarn 34 and operate to dispose pile yarn loops 36 in piercing relationship to the backing 32. An adhesive back coating 38 may be applied to the primary backing 32 so as to anchor the pile yarns 34 more firmly in place. Dimensional stability of the tufted pile fabric may be enhanced by adhering a secondary backing 40, e.g. a woven jute scrim, to the back face of the primary backing.
The primary backing 32 of the tufted pile fabric illustrated in FIG. 3 is designed to be amenable to rot and mildew resistance treatments as well as flame retardancy treatments.
Anexample of the rot and mildew resistance treatments to which the backing may be subjected is one in which a trimethylol melamine, such as that sold by Ciba Company, Inc. under the designation Arigal C, is padded to the backing in a concentration to yield 7% add-on. The pad bath also contains 5-10 g/l of 30% hydrogen peroxide. A wet fixation procedure (described in American Dyestuff Reporter, Vol. 50, No. 20, 21, 1961) accomplishes conversion of the trimethylol melamine to an insoluble resin within the fibers. This treatment is permanent to washing and leaching. A further understanding of treatments of this type may be gained from US. Pat. No. 2,763,574.
Numerous durable fire retardant treatments for cotton and semidurable fire retardant finishes for cotton would be acceptable. As an example of an appropriate durable treatment, the fabric may be padded to approximately 75% wet pickup with a water solution of the following content:
Polyvinyl chloride 9.4%
S 0 10.1% Tetrakis (hydroxymethyl) phosphonium chloride 10.4%
Trimethylol melamine 7.8%
Wetting Agent 0.5%
The fabric is then dried on a tenter frame, cured 2 minutes at 320 F., and given an alkyline, oxidizing wash.
A suitable commercial semi-durable fire retardant finish for cotton involves padding the fabric to approximately 70% wet pickup of a water solution of cyanamide 30% and phosphoric acid 20%. The fabric is dried 2 minutes at 65 C., and cured 4 minutes at 105 C.
Thus, through the above or similar treatments, one may insure that the backing of the present invention does not contribute to the flammability or rot and mildew deterioration of the carpet.
It will also be seen that according to the present invention a primary backing for a tufted fabric may be formed from cotton fibers so that the backing has satisfactory mechanical properties necessary for that function. Basically, these properties may be characterized as tuftability, or the ability of the primary backing to maintain adequate strength across the tuft line, and "tuft lockability, or the ablity of the backing to recover from deformations caused by tufting needles and to thereafter squeeze in on the pile yarns which pierce the primary backing.
The provision of tuftability and tuft locking characteristics in the primary backing of the present invention is particularly significant when the shortness and thinness of the fine fiber content of the backing is considered. A typical tufting machine provides 7 to 10 tufts per inch along the tuft line with 6% to 10 tuft lines per inch. The problem presented by such loading may be readily appreciated by reference to FIG. 4 which illustrates at 42 the areas blocked off by the tufting needles 42. These needles are mounted with their long sides set at about 30 to the tuft line, indicated at 44. The distance between the tuft lines of 3.9 millimeters is represented by the arrow 46, and the distance between tufts in a line of 3.6 millimeters is represented by the arrow 48.
Since, at this tuft density, the rectangles representing the area blocked out by the needles 42 overlap along the tuft line 44, it is readily apparent that if the backing is not able to distort ahead of and behind the needle, all fibers crossing the tuft line will be cut so that the backing will deteriorate. Additionally, it may be noticed that as the fibers are displaced from the center of the needle to the outer comers of the rectangle representing the area blocked out by the needle along the tuft line, stresses tending to tear the backing across a line perpendicular to the tuft line will result. Moreover, as indicated by the circles 50 the backing must recover a considerable amount to close about the yarn penetrating the backing.
Through the provision of a nonwoven base web having a short fine fiber content and a longer coarser fiber content as discussed above, the fiber network is sufficiently mobile and deformable to impart good tuftability and tuft locking properties to the web despite the predominately present fine fibers.
Through the practice of the present invention, a primary backing of attactive cost and performance characteristics is thus provided by employing a fine fiber content which would normally be thought nonsusceptible to tufting in an acceptable manner. Moreover, the aspect of the invention involving amenability to rot and mildew resistance treatments and flame retardancy treatments is particularly significant.
In addition, it will be appreciated that according to the present invention the amenability of the backing to dyeing eliminates grinning problems, or the need for special techniques to combat grinning problems, while retaining the advantages of a nonwoven fiber network.
Although the invention has been described with reference to preferred forms and techniques, it will be appreciated by those skilled in the art that additions, modifications, substitutions and deletions may be made by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
What is claimed is:
1. A tufted pile fabric comprising a primary backing and pile yarns piercing said backing, said primary backing including a nonwoven base web of fibers crossing in a network of individual fibers and consisting essentially of:
25 to percent by weight of a fine fiber content comprised of fine staple fibers having widths corresponding to deniers of up to about three and lengths less than about 3 inches, and
75 to 25 percent by weight of a coarse fiber content comprised of synthetic fibers having deniers in the range of from about 6 to about 20 and having lengths of at least about 4 inches,
said fibers of said network of individual fibers being bonded together at a number of fiber crossing points to impart structural strength to the base web.
2. A tufted pile fabric according to claim 1 wherein said fine staple fibers include cotton fibers.
3. A tufted pile according to claim 1 wherein the denier of said synthetic fibers is in the range of from about 10 to about 20.
4. A tufted pile fabric according to claim 1 wherein said base web consists essentially of about 60 percent by weight of said fine fiber content and about 40 percent by weight of said coarse fiber content.
5. A tufted pile fabric according to claim 4 wherein said fibers of said coarse fiber content are fifteen denier polyester fibers about 4 inches long and wherein said fibers of said fine fiber content are cotton fibers.
6. A tufted pile fabric according to claim 1 wherein said nonwoven base web is needled.
7. A tufted pile fabric according to claim 1 wherein said primary backing includes reinforcing members attached to said nonwoven web.
8. A tufted pile fabric according to claim 7 wherein said reinforcing members comprise yarns stitched into said nonwoven base web in a tricot pattern.
9. A tufted pile fabric comprising:
a primary backing including a nonwoven base web of carded fibers crossing in a network of individual fibers and being crosslapped, essentially consisting of 50 to 75 percent by weight of a fine fiber content comprised of cotton fibers, and
50 to 25 percent by weight of a coarse fiber content comprised of synthetic fibers selected from the group consisting of polyolefin and polyester, said synthetic fibers having deniers in the range from about 10 to about 20 and having lengths of at least about 4 inches,
said fibers of said network of individual fibers being bonded together at a number of fiber crossing points to impart structural strength to the base web with said fibers of said coarse fiber content serving as carriers of said fibers of said fine fiber content during tufting, and being locked together in a three-dimensional array, and
continuous strands reinforcing said nonwoven base web; and
pile projections piercing said primary backing.