US3348993A - Fabrics - Google Patents

Description

C. R, SISSONS FABRICS -F'iled NOV. 27, 1964 Attorneys' United States Patent Cfiice 3,348,993 Patented Oct. 24, 1967 3,348,993 FABRICS Christopher Robert Sissons, Raglan, England, assignor to British Nylon Spinners Limited, Monmouthshire, England Filed Nov. 27, 1964, Ser. No. 414,242 Claims priority, application Great Britain, Nov. 29, 1963, 47 ,217 63 17 Claims. (Cl. 161-67) This invention relates to nonwoven fabrics and is particularly concerned with nonwoven fabrics resembling pile fabrics, and to methods and apparatus for making them.

Nonwoven fabrics in various forms have been known for many years. Within the last decade or so a considerable volurme of literature, including many patent specifications, has been published in connection wit-h the making of nonwoven fabrics by a technique involving the needling of a fibrous web. Much of the endeavor in this particular field of nonwoven fabrics, as evinced by publications known to use, would appear to have been directed to the making of fabrics resembling felts. Felts are fabrics possessing a dense, compact structure of high density and consequently, they are restricted in the end uses to which they can be applied.

An object of this invention is to provide a needled fabric which resembles a pile fabric and which finds application in end uses for which pile fabrics of a conventional nature are generally suitable. Such a fabric is distinguished from a felt by the presence therein of a multitude of fibres extending outwardly from a surface of a base structure in the form of fibre tufts which provide the fabric with its pile surface.

Another object of this invention is to provide a pile fabric of novel structure and exhibiting advantageous properties.

A further and more specific object of this invention is to provide a nonwoven pile fabric wherein the pile surface is formed of fibre tufts exhibiting a good permanence of forni.

A still further object of this invention is to provide a method and apparatus for making the fabrics of this invention.

These and still other objects and advantages will be apparent from the following description and appended claims.

Thus, according to one aspect of this invention there is provided a nonwoven fabric having an integral structure and simulating a conventional pile fabric, which fabric comprises a stratum of fibre tufts and a base stratum in the form of a fibrous web, said fibrous web base stratum containing fibres located in planes normal or substantially so to the planar surfaces of the stratum, which fibres project beyond a planar surface of the base stratum as fibre tufts thereby providing the fabric with a pile surface, said fibre tufts being set in the base stratum.

For convenience, and because the nonwoven fabrics of this invention have the appearance of a conventional pile fabric, they will often be referred to herein simply as pile fabrics.

The pile fabrics of this invention may be made by a method involving the needling of a fibrous web located on a support material thereby fonming a composite needled structure in which fibre tufts extend from the web into the support material, subjecting said structure to a setting treatment to set the fibre tufts and thereafter separating the needled brous web from the support material.

The needled fabric so formed resembles a conventional pile fabric in that it contains a multitude of fibre tufts projecting out of the fibrous web base stratum.

The effect of needling is to reorientate some of the fibres in the fibrous web into planes normal or substantially so to the planar surfaces of the web so that the web contains vertically disposed fibres which extend beyond a surface of the web, into the support material, as fibre tufts.

Consequently, each fibre tuft represents the extension of vertically disposed fibres embedded in the fibrous web, and the embedded fibres may be likened both structurally and functionally to the roots of a tree.

The setting treatment to which the composite needled structure is subjected, which expression embraces any treatment wherein the fibre tufts are secured more firmly to the fibrous web base stratum than they were prior thereto, confers upon the resulting pile fabric good tuft retention and consequently provides a pile surface possessing a good resistance to destruction, permanence of form and a long wear life.

In accordance with one embodiment of this invention, a fibrous web of desired weight and structure is placed in surface contact with a loosely woven fabric as support material. The assembled web and fabric are then needle punched in a conventional needle loom, the woven fabric serving to lend effective support to the fibrous web in the needling operation, notwithstanding the fact that the web may be light-weight and unbonded. The composite needled structure so formed is thereafter subjected to a setting treatment whereby the fibre tufts are fixed in the configurations resulting from needling. The needled fibrous web with the fibre tufts secured therein so as to provide the structure with a pile surface, is then separated from the woven support material.

The present invention further includes apparatus for making a nonwoven fabric simulating a conventional pile fabric which comprises a needle loom for needling fibres of a fibrous web into a support material, means for setting the fibre tufts so formed, and means for separating the needled fibrous web from the support material.

The fibrous web may be composed of any conventional textile fibre, which term includes filaments and embraces both staple fibres and continuous filaments, for example, natural fibres such, for example, as cotton or wool, manlmade fibres such, for example, as viscose rayon, cellulose acetate and similar derivatives of cellulose, proteinaceous polymers, polyamides, for example, poly(hexamethylene adipamide), poly(hexamethylene sebacamide), poly(epsilon caprolactam) and copolymers of these or other polyamides, polyesters, for example, poly(ethylene terephthalate), polyurethanes, acrylonitrile polymers including copolymers of acrylonitrile, especially with other ethylenically unsaturated monomers such as vinyl chloride, vinyl acetate, methyl acrylate, and vinyl pyridine, vinyl polymers generally for example, polyvinyl acetate, polyvinyl chloride, and polystyrene, and polymerized hydrocarbons, for example, poly(ethylene) and poly(propylene) and halogenated derivatives thereof or any mixtures of such fibres. l

In a particularly useful embodiment of this invention the fibrous web consists of, or contains, heterofilaments which may be in the form of continuous filaments or staple fibres. Conveniently, the heterofilaments comprise at least two synthetic polymer components at least one of which can be rendered adhesive under conditions which leave the other component or components substantially unaffected, the potentially adhesive component occupying at least a portion of the peripheral surface of the fibre or filament.

In another embodiment of this invention the fibrous web may be fabricated from a blend of heterofilament and homofilament. Suitable homofilaments include those listed above. The fibres of which the web is formed may contain pigments, fillers, abrasives and/ or light stabilizers.

The fibrous web may be fabricated in a number of ways, and the method selected in a particular instance, depends to a very large extent on the length of the fibres, when fibres other than continuous filaments are used. Staple fibre, continuous filament and continuous filament yarn webs are all suitable for use in this present invention.

Staple fibre webs may be prepared, for example, by a woolen or cotton carding machine, or a garnetting machine which result in a web in which the staple .fibres are oriented predominately in one direction. The thin web obtained froma single card or garnet may be used by itself but generally it is necessary and desirable to superimpose a plurality of such webs to build up the web to a sufficient thickness and uniformity for the end use `intended. In buildingr up such a web, alternate layers of carded webs may be disposed with their fibre orientation directions disposed at a certain angle, conveniently 90, with respect to intervening layers. Such cross-laid webs have the advantage of possessing approximately the same strength in at least two directions. Furthermore, cross lapping in this manner provides a product having a balanced stretchability. Random or isotropic staple fibre webs may be obtained, for example, by air-laying staple fibres. Thus, one staple fibre web suitable for use in the process of this invention may be obtained by feeding continuous filaments to a cutter or breaker which discharges the fibres into an air stream produced by the blower. Suitable conduits are provided to guide a suspension of the staple fibres, in a current of air to a foraminous surface on which the fibres settle as an interlaced and matter layer preferably being encouraged to do so by the application of suction on the other side of said surface. The foraminous surface can be in the form of an endless belt which is caused to travel pastthe place at which the fibres are fed toit, so as to form a continuous layer of indefinite length. Paper-making techniques may also be employed in the making of staple fibre webs.

Continuous filament webs may conveniently be prepared by drawing off directly from a spinning (i.e. polymer extrusion) unit, or they may be formed from a package or other storage device for yarn (multifilaments) or monofilament already spun.

Continuous filament yarn webs, that is to say, webs in which the filaments are present as multilaments, may conveniently be prepared in a process wherein freshly .spun filaments comprising one or more polymer components are subjected to the action of a high velocity turbulent fluid jet which attenuates and orients the filaments and intermingles them to form a twistless yarn, which yarn is forwarded by the fluid jet and deposited on a receiving surface in a random loopy manner.

The fibres in the fibrous web may be crimped or shrunk, or potentially crimpable or shrinkable, to provide the pile fabric product with better developed or additional desir able properties such as an increased resiliency anda betterdeveloped loft.

The` material employed to support the web in the needling operation and into which fibres are needled may be a woven fabric or a fabric having the structure of a woven fabric, for example, an air-laid scrim fabric. Alternatively, a perforated metal screen may be used as the support material in which event synchronization of the speed at which the screen (with the web thereupon) is passed through the loom with the rate of needling is required.

The support material, in theneedling operation, must be disposed against the surface of the fibrous web which is opposite the surface adjacent the punching board, so that the needles during the needling first encounter the fibres of the web.

Quite apart from the role which it plays in the needling operation, when it provides a foundation for the fibrous web, the support material is important in ensuring good tuft definition and, in this connection, it may be considered as a mold serving to locate and shape the fibre tufts needled into it and thereafter hold them in place until the setting thereof. Furthermore, the thickness of the support material is a factor which determines the pile height of the resulting pile fabric.

The treatment to which the composite needled structure is subjected for the purpose of setting the fibre tufts, may take a variety of forms, but I have found that regardless of differences of detail, particularly successful and convenient treatments are those which result in the direct or indirect bonding of fibres in the fibrous web base stratum. As a result of this bonding the roots of the fibre tufts, that is to say, the vertically disposed fibres embedded in the fibrous web, are fixed in position and consequently the fibre tufts are locked in their needled configurations and so there is good tuft retention in the resultingy pile fabric.

The particular treatment used to bond fibres, and thereby set the fibre tufts is largely dependent upon the nature of the fibres constituting the fibrous web. Thus, when the fibres of the web are simple one component fibres i.e. homofilaments, it is often advantageous to set the fibre tufts by means of an adhesive applied in some manner to the fibrous web, are fixed` in position and consequently roots of the fibre tufts are cemented together.

Another method of bonding such fibres involves incorporating or introducing into the web a bonding agent which is potentially adhesive under conditions which do not af-v fect fibres in the web. For example, the bonding agent may have a softening point below the .softening or decomposition point of fibres in the web and hence can be rendered adhesive, i.e. activated, by heat, `or the bonding agent may be capable of being activated by some Chemical means.` Such bonding agents are frequently in the form` of powders, fine flock or fibres.

In another method of bonding such fibres, distinguished from the previously discussed methods in that it results in the coalescence of fibres in the fibrous web i.e. direct or fibre-bre bonding, the structure is treated with a substance which causes fibres in the web to become tacky and so stick together at points of contact and cross-over. Formaldehyde, nitric acid and phenol are examples of substances which, when used with fibrous webs containing polyamide fibres, render the surface of the fibres tacky.

When the fibrous web contains heterofilaments of the type which comprise at least two synthetic polymer components, one of which components is potentially adhesive. By the potentially adhesive component we mean a component the adhesive `characteristics of which can be developed without affecting any other component of the composite fibres and forconvenience and to distinguish it from the remainder of the filaments the same expression is used in relation to the same component of the composite fibres in the bonded structure. The potentially adhesive component should be arranged to form at least a portion of the periphery of the fibre. The tufts may conf veniently be set by exposing the composite needled structure to conditions which activate i.e. render adhesive, the one component.

Particularly suitable heterofilaments are those in which the potentially adhesive component has a lower softening n point than the other component or components and is thus heat activatable. As examples of such heterofilaments I may mention poly(epsilon caprolactam)/poly(hexameth yleneadipamide) (6/66 nylon) filaments in which poly (epsilon caprolactam) is the lower melting component, and poly(omega-aminoudecanoic acid) /poly(hexamethyl ene adipamide) (1i/66 nylon) filaments in which the poly(ornegaraminoundecanoic acid) component has the lower melting point, and poly(hexamethylene adipamide) poly(hexamethylene adipamide)-poly(epsilon caprolactam) copolymer (66/666 nylon) in which the copolymer component has the lower melting point. Heterofilaments based on systems other than the polyamide system may also be used. Thus, the heterofilaments may be prepared from polymers based on, for example, polyesteramides, polyesters, polyurethanes, polyolefins, polyacrylonitrile, or polyvinylidene chloride.

The potentially adhesive component of the heterofilament maybe such that it can be activated7 and the tufts thereby set, by chemical means, for example, by treatment with an essentially non-aqueous solution of formaldehyde. An example of such a heterofilament is one consisting of poly(hexamethylene adipamide) as one component, and an 80/20 random copolymer of poly(hexamethylene adipamide) and poly(epsilon caprolactam) as the other component, in which the copolymer component can be activated by means of a hot essentially non-aqueous, for example, an ethylene glycol solution of formaldehyde, treatment under controlled conditions which leaves the poly(hexamethylene adipamide) component substantially non-adhesive. After setting, the solvent or other chemical means employed for activating the potentially adhesive component is removed by any suitable means, such as evaporation or washing with a liquid miscible with, for example, the aforementioned formaldehyde but inert towards the fibres in the fabric.

The incorporation in the fibrous web of at least a certain proportion of heterofilaments of the type previously described, permits the tufts to be set, in a convenient and efficient manner as a result of what in essence is an in situ development of a bonding agent through the activation of a potentially adhesive component of the heterofilaments.

The activation of the potentially adhesive component is normally accomplished Without destruction of the fibrous character of the heterofilament, for the activated component is maintained in contiguous association with the other component, and thus retention of fibrous character is believed to be of importance in properties such as the tuft definition and retention, properties which contribute toward determining the permanence of the pile surface, and also the dyeability of the resulting pile fabric. In addition, the use of heterotilaments allows precise control of the quantity of binder and uniform disposition throughout the fibrous web to be readily attained. Furthermore, when heterofilaments are employed in the fibrous web crimping of the fibres therein may be achieved in the same treatment as that used to set the tufts.

The fabrics of this invention resemble conventional pile fabrics in appearance and they possess many desirable properties including a good tensile strength and a generally pleasant handle. Furthermore, the pile surface which is formed from well defined fibre tufts, exhibits a good permanence of form and the tuft retention is uniformly good.

To a certain extent the properties of the pile fabrics of this invention are a reflection of the fibres constituting the fibrous web. Thus, pile fabrics derived from webs containing polyamide fibres have good abrasion resistance.

An advantage possessed by the instant pile fabrics is that they are homogenous fabrics, in the sense, that the fibre tufts and the body of the fabric (fibrous web base stratum) are of the same material, which means that the effective life of the fabric is enhanced relative to pile fabrics containing two or more phases.

The pile fabrics of this invention are versatile in application although they are particularly suited for use as fioor-covering materials, upholstery fabrics and in soft goods such as slippers and toys.

It may sometimes be advantageous to provide the pile fabrics `of this invention With a backing. Suitable backings include adherent backings such, for example, as rubber, polyvinyl acetate, polyvinyl chloride or a polyurethane foam.

The invention is further described in the following illustrative examples and the accompanying drawings wherein.

FIGURE l is a diagrammatic view sequentially illustrating one embodiment of the process of this invention and showing the apparatus employed;

FIGURE 2 is a perspective view, from below, showing the composite needled structure prior to setting the fibre tufts;

FIGURE 3 is a cross-section of a pile fabric according to this invention.

In FIGURE 1 there is shown a supply roll 10 for an open weave material such as hessian 11, which is unwound from the supply roll and horizontally moved from left to right on the surface of an endless belt 12. Layer 13 so formed is intended to be used as the support material for a fibrous web. Reference numeral 14 designates a supply roll of a fibrous web 15 comprising containing, heterofilaments which is being continuously superimposed, with the aid of a roller 16, as a layer 17 upon the hessian support 13 and moved at the same rate and in the same direction as the hessian. A carding, garnetting, or air-laying machine, or indeed any means for forming a fibrous web may take the place of the supply roll 14.

The layered assembly is then fed to a needle loom, indicated generally by reference numeral 18, of conventional design. Needle loom 18 comprises a horizontal surface 19 supporting the layered assembly comprised of fibrous web 17 and hessian 13 and a needle board 20. The needle loom 18 reciprocates needles into and out of the fibrous web, and reorients some of the fibers of the fibrous web into planes normal or substantially so to the planar surfaces thereof, the vertically disposed fibres projecting beyond a planar surface into the hessian as fibre tufts. The needle punched structure on emerging from the needle loom is illustrated in FIGURE 2 which shows fibre tufts 25 protruding through interstitial spaces 26, i.e. spaces between the warp 27 and weft 28, in the liessian 13 which serves as a mold for locating, shaping and then holding the fibre tufts in position until the setting thereof.

The composite needle structure 21 is then carried through an oven 22, in which the tufts are set as a result of the bonding together of fibres in the fibrous web. After the structure leaves the oven, the needle fibrous web 23 is continuously separated from the hessian support material 13 and is wound up on a product reel 24. The tufts are retained in the needle fabric, and do not disappear on the separation from the hessian, and consequently the needle fibrous web resembles a pile fabric.

FIGURE 3 shows irl cross-section the detailed structure of the pile fabric. The two strata, that of the fibre tufts indicated by reference numeral 29, and the fibrous web base stratum indicated by reference numeral 30, can readily be distinguished. The individual tufts 31 are the projecting portions of vertically disposed fibres 32 embedded in the fibrous web base stratum 30, and the aptness of the term root applied to fibres 32 will be apparent. The vertical disposition of the fibres 32 is owed to needling which reorients those fibres into planes normal or substantially so to the planar surfaces, indicated here by reference numerals 33 and 34, of the fibrous web. The pile fabric, the cross-sectional View of which is illustrated in this figure, was derived from a fibrous web containing heterofilaments and the crumpling of the tip of each tuft 31, with the formation of cap 35, which gave the tuft the appearance of a mushroom, is due to a crimping of the free portion of each heterofilament tuft during the setting treatment in the oven. The crumpling of the tufts in this manner confers upon the pile fabric product certain advantageous properties, notably an increase in the tuft spread with correspondingly more effective concealment of the base stratum.

EXAMPLE 1 50 gms. of 6 denier, two and one quarter inch staple fibres formed from a heterofilament comprising equal proportions by weight of poly(hexamethylene adipamide) as one component and an /20 poly(hexamethylene adipamide)-poly(epsilon caprolactam) copolymer as the other component, the two components being arranged side-by-side and the heterofilament containing l0 crimps per inch, was carded into a web by a Shirley miniature carder. The web was deposited on a sheet of hessian fabric itself supported on an endless moving belt, and the assembly was then needle punched by means of a conventional needle loom made by William Bywaters Ltd., equipped with 32 gauge regular barb needles. The assembly was run through the needle loom with the hessian beneath the fibrous web so that the reciprocating needles penetrated first the web and then the hessian. The needle penetration was adjusted to penetrate LVs inch and the rate of needling was adjusted to effect 300 punches per square inch. The hessian effectively supported the fibrous web in the needling operationwhich reoriented some of the fibres in the web into planes normal, or substantially so, to the planar surfaces of the web. Those vertically disposed fibres were continued beyond the planarsurface in contact with the hessian as fibre tufts which themselves entered the interstitial spaces (i.e. the space between weft and warp threads) in the hessian which, in this connection, served as a mold for locating, shaping and then holding in position the fibre tufts. The composite needle fabric was then heated in an air oven for three and a half minutes at a temperature of 240 C.

As the fibres attained the ambient oven temperature, the lower melting copolymer component of the heterofilament as the potentially adhesive Component became adhesive and caused the fibres in contact with one another to stick or fuse together and so set the fibre tufts. It was observed that only a small amount of web to hessian adhesion had taken place. On removing the fabric from the oven slight pressure was applied thereto in order to effect some degree of attening. After cooling, the hessian backing was removed by gentle pulling apart,.to leave a pile fabric of pleasant appearance and handle. The.

fabric weighed 8 ozs.. per square yard, and had a pile height of 3/s inch.

The strength of the pile fabric .in the longitudinal direction was determined on a sample, approximately cms. long and 2 cms. wide, which was clamped between the jaws of an Instron Tensile Tester, the jaws being set l0 cms. apart. The load and percentage extension to break were measured and the strength calculated.

Details of the measurement etc. are as follows:

Fabric weight (ounces/sq. yard) 8 Weight per unit length (gm/cm.) 0.056 Load to break (kg.) 12.0 Extension to break (percent) 18 Tensile strength (kg./gm./cm.) 214 FIGURE 5, which is a photomicrograph of a crossscction of the pile fabric shows very clearly the well-defined fibre tufts 36 providing the fabric withits pile surface and which projects beyond, and out of, the fibrous web base stratum 37 within which their roots are embedded. The good tuft definition and retention, and the good permanence of form exhibited by the pile' fabric was attributed, at least in some measure, to the effective setting of the fibre tufts which resulted from the presence in the fibrous web of heterofilaments. The effective setting so manifest was explained by the unique disposition of bonding agent, i.e., the potentially adhesive cornponent, then obtained throughout the web, which was refiected in the well-developed direct, i.e. fibre-fibre, bonding through the fibrous web base stratum which included the region, indicated by the reference numeral 38 in FIGURE 5, toward the top surface of the fibrous web base stratum where the roots, i.e. vertically disposed fibres, embedded therein were about to emerge yfrom the web in the form of fibre tufts.

Since the pile fabric had a homogenous structure,.in the sense, that is consisted entirely of fibres which were selected from the same chemical classification i.e. all the fibres had the same functional groups, it was readily dyed uniformly with only one dyestuff. The pile fabric of this invention was dyed with `an acid type dyestuff, for example, Solway Blue, used for polyamide dyeings, the result- EXAMPLE 2 The procedure set forth in Example 1 was repeated, except that the staple fibre web was formed of heterofilaments comprising equal proportions by Weight of poly- (hexainethylene adipamide) as one component and poly- (omega-aminoundecanoic acid) as the other (potentially adhesive component), the two components being arranged in a side-by-side relationship. The pile fabric product had an appearance very similar to the fabric of Example 1.

The strength of the fabric in the longitudinal direction was determined in a manner identical to that used in the foregoing example.

Details of the measurements etc. are as follows:

Fabric weight (ounces/sq. yd.) 7.5 Weight per unit length (gm/cm.) 0.039 Load to break (kg.) 13.0 Extension to break (percent) 27 Tensile strength (kg./gm./cm.) 334 EXAMPLE 3 A mixture comprising percent 12 denier, two and a quarter inch poly(hexamethylene adipamide) staple fibres and percent 9 denier, two and quarter inch staple fibres formed from a heterofilament comprising as one component, a copolymer consisting of partsy by weight of poly(epsilon caprolactam), and as the other component, poly(hexamethylene adipamide), the two components being arranged side-by-side was carded into a web. A nurnber of such webs were laid upon one another, with their fibre orientations disposed at angles with respect to intervening layers, to form a cross-laid web.

This web was laid on a sheet of hessian fabric itself supported on an endless moving belt, and the assembly then needle punched by the procedure set forth in Exam-r ple l. The composite needled fabric was then heated in an air oven for a period of four minutes at a temperature of 240 C. The effect of this heat treatment was to activate the copolymer component of the heterotilaments which developed its adhesive characteristics and so caused fibres in contact with one another to stick or fuse together thereby setting the fibre tufts. It was observed that little adhesion occurred between kthe fibrous web and the hessian. On moving the fabric fromthe oven slight pressure was applied thereto to effect some degree of fiattening. After cooling, the hessian was separated from the needled web by gentle pulling apart to leave Vas the product a pile fabric. The fabric had a weight of 9 ors/yd.2 and a pile yheight of $46 inch.

A random staple fibre web weighing 8 ozs./yd.2 was prepared by air-laying two inch poly(hexamethylene adipamide) staple fibres. This was laid on a sheet of a hessian fabric having a weight of 10 ozs./yd.2.

The layered assembly was then needle punched as in Example 1, the speed of the assembly through the needle loom being adjusted toeffect 250 punches per square inch with a penetration of 57s inch.

The composite needled fabric was then immersed for 2O secs. at room temperature in 4.8 N nitric acid contained in a lbath and thereafter immediately washed in a continuous stream of cold water for 2 minutes. As a consequence of the nitric acid treatment, the surface of the poly(hexamethylene adipamide) fibres became sticky and, in that condition, caused the bonding together of adjacent i fibres in the fibrous web thereby setting the fibre tufts. The

bonding together of libres was accomplished without any appreciable adhesion between the web and the hessian.

The hessian Was separated from the needled web by a gentle pul-ling apart and a pile fabric exhibiting good tnft definition and an excellent resistance to abrasion was obtained.

The strength of the fabric in the longitudinal direction was determined in a manner identical to that used in Example l.

Details of the measurements etc. are as follows:

Fabric weight (ounces/ sq. yd.) 8 Weight per unit length (gm./cm.) 0.045 Load to break (kg.) 4.4 Extension to break (percent) 32 Tensile strength (kg./gm./cm.) 98

In relation to the pile fabrics of the previous examples it was noted that the instant pile fabric had a somewhat harsher handle and was less strong.

The setting of the poly(hexamethylene adipamide) fibre tufts may be accomplished by a chemical medium other than nitric acid. Thus, a formaldehyde solution, for example, a solution of formaldehyde in glycerol, a phenol solution, for example, a solution of phenol in ethanol, and a meta-cresci solution, for example, a solution of meta-cresol in ethanol, are other chemical media by means of which the fibre tufts may be set.

EXAMPLE A mixture comprising equal proportions by weight of 6 denier, two inch poly(hexametnylene adipamide) staple libres and 3 denier, one and a half inch poly(propylene) fibres was carded on a Shirley miniature card. A number of the webs so formed were laid upon one another, with their libre orientations disposed at 90 angles with respect to intervening layers, to form a cross-laid web having a weight of approximately ounces per square yard. This web was laid on a sheet `of hessian fabric having a weight of approximately l0 ounces per square yard and the layered assembly needle-punched in the manner described in Example 1 except that the assembly was passed through the machine several times until a punch density 0f approximately 700 punches per square inch had been attained. The composite needled fabric was then passed through an Efco -conveyorized oven operating at a throughput of ten feet per minute and a temperature of 210 C. The effect of this heat treatment was to fuse the poly(propylene) libres which, in that condition, bonded together fibres in the fibrous web and thereby set the fibre tufts. Following this setting treatment, and after cooling, the hessian was removed from the needled web by a gentle pulling action, to leave a pile fabric of pleasant appearance and handle. The fabric was a useful substitute for upholstery fabrics of the moquette type.

EXAMPLE 6 A mixture comprising 80 percent 6 denier, two inch staple fibres formed from heterofilaments consisting of equal proportions by weight of poly(hexamethylene adipamide) and an 80/20 poly(hexamethylene adipamide)- poly(epsilon caprolactam) copolymer, the two components being arranged side-by-side and percent Wool libres was carded using a Shirley miniature card, and several of the Webs so formed cross-laid into a web having a weight of approximately l0 ounces per square yard. This cross-laid web was then laid on a sheet of hessian fabric having a Wei-ght of approximately l0 ounces per square yard and the layered assembly so formed needle punched in the manner `described in Example l except that the assembly was passed through the machine several times until a punch density of approximately 600 punches per square inch had been attained. The composite needled fabric was then passed through an Efco conveyorized oven operating at a throughput of 10 feet per minute and a temperature of 230 C. At this temperature the copolymer component of the heterolilaments was activated, develope-d its adhesive characteristics, and in that condition, bonded together fibres in the fibrous web, thereby setting the libre tufts. The product obtained on removing the hessian resembled a conventional pile fabric. It had good tuft definition and retention, a pleasant handle and an excellent tensile strength. The fabric made a useful lioor covering material. When utilized for this end use it was sometimes found advantageous to provide the fabric with a backing, for example, of rubber, or polyurethane.

Since it is apparent that many changes and modifications can be made in the above-described detailed specification without departing from the nature and spirit of the invention, it is to be understood that the invention is not to be limited except as set forth in the appended claims.

What I claim is:

1. A non-woven fabric having an integral structure and simulating a conventional pile fabric, which fabric comprises a stratum of fibre tufts and a base stratum in a form of a fibrous web, said fibrous web base stratum containing fibres located in planes at least substantially normal to the planar surfaces of the stratum, which fibres project beyond a planar surface of the base stratum as fibre tufts thereby providing the fabric with a pile surface and said fibrous web comprising at least a proportion of composite libres comprising at least two fibreforming synthetic polymeric components arranged in distinct zones across the cross-section of each fibre and at least one and less than all of the components being potentially adhesive and located so as to form at least a portion of the peripheral surface of each fibre, said composite fibres being adhesively bonded to contiguous libres in the structure through the agency of said potentially adhesive component thereby securing tufts in the structure.

2. A non-woven fabric according to claim 1 in which the tops of the tufts are crimped, said crimping resulting from differences in physical properties of the components of the composite libres.

3. A non-woven fabric according to claim 1 in which the composite fibres contain two components the potentially `adhesive component being poly(omegaaminodecanoic acid).

4. A non-Woven fabric according to claim 1 in which the composite libres contain two components, the potentially adhesive component being poly(epsi1on caprolactam).

5. A non-woven fabric according to claim 3 in which the other component is poly(hexamethylene adipamide).

6. A non-woven fabric according to claim 4 in which the other component is poly(hexamethylene adipamide).

7. A non-woven fabric according to claim 2 in which the composite fibres contain two components, the potentially adhesive component being poly(omegaaminodec anoic acid).

8. A non-Woven fabric according to claim 2 in which the composite fibres contain two components, the potentially adhesive component of the composite fibres being poly(epsilon caprolactam).

9. A non-woven fabric according to claim 7 in which the other component is poly(hexamethylene adipami-de).

10. A non-Woven fabric according to claim 8 in which the other component is poly(hexamethylene adipamide).

11. A method of making a non-woven fabric having an integral structure and simulating the conventional pile fabric which comprises forming a fibrous web containing at least a proportion of composite fibres, said composite fibres comprising at least two fibre-forming synthetic polymeric components arranged in distinct zones across the cross-section of each libre and at least one, and less than all, of the components being potentially adhesive and located so as to form at least a portion of the peripheral surface of each fibre, locating said fibrous web on a foraminous support, needling said fibrous web and said foraminous support so that fibre tufts extend from the web into and through the foraminous support, sub-fy jecting the resulting structure to a treatment to render` adhesive the said potential component thereby adhesively bonding the composite fibres to conti-guous fibres in the structure and securing the said fibre tufts in the structure, and thereafter separating the needled fibrous web from the foraminous support.

12. A method of making a pile fabric as claimed in claim 11 in which said Web is formed of composite fibres which also possess potential crimp as a result of a difference in the physical properties of their components and in whichtsaid treatment also develops said Crimp in said composite fibres where they extend from the foraminous support.

13. A method of making a non-Woven fabric as claimed in claim 11 in which said structure is subjected to a heat treatment to render adhesive said potentially adhesive component.

14. A method of making a non-Woven fabric as claimed in claim 11 in which said structure is subjected to the action of a suitable chemical medium to render adhesive said potentially adhesive component.

15. A method of making a non-woven fabric as claimed in claim 12 in which said structure is subjected to a heat treatment to render adhesive said potentially adhesive component and develop said crimp.

16. A method of making a non-woven fabric as claimed in claim 12 in which said structure is subjected to the action of a suitable chemical medium to render adhesive said potentially adhesive component and develop said crimp.

17. A method as in claim 11 in which, during said needling step, the needles pass through said fibrous web before encountering said foraminous support.

References Cited UNITED STATES PATENTS 2,331,321 10/1943 Heaton 161-81 2,959,509 11/ 1960 Marshall 161-81 2,970,365 2/1961 Morgenstern 156-148 X FOREIGN PATENTS 826,163 12/1959 Great Britain.

ALEXANDER WYMAN, Primary Examiner.

R. H. CRISS, Assistant Examiner

Claims (1)

1. A NON-WOVEN FABRIC HAVING AN INTEGRAL STRUCTURE AND SIMULATING A CONVENTIONAL PILE FABRIC, WHICH FABRIC COMPRISES A STRATUM OF FIBRE TUFTS AND A BASE STRATUM IN A FORM OF FIBROUS WEB, SAID FIBROUS WEB BASE STRATUM CONTAINING FIBRES LOCATED IN PLANES AT LEAST SUBSTANTIALLY NORMAL TO THE PLANAR SURFACES OF THE STRATUM, WHICH FIBRES PROJECT BEYOND A PLANAR SURFACE OF THE BASE STRATUM AS FIBRE TUFTS THEREBY PROVIDING THE FABRIC WITH A PILE SURFACE AND SAID FIBROUS WEB COMPRISING AT LEAST A PROPORTION OF COMPOSITE FIBRES COMPRISING AT LEAST TWO FIBREFORMING SYNTHETIC POLYMERIC COMPONENTS ARRANGED IN DISTINCT ZONES ACROSS THE CROSS-SECTION OF EACH FIBRE AND AT LEAST ONE AND LESS THAN ALL OF THE COMPONENTS BEING POTENTIALLY ADHESIVE AND LOCATED SO AS TOFORM AT LEAST A PORTION OF THE PERIPHERAL SURFACE OF EACH FIBRE, SAID COMPOSITE FIBRES BEING ADHESIVELY BONDED TO CONTIGUOUS FIBRES IN THE STRUCTURE THROUGH THE AGENCY OF SAID POTENTIALLY ADHESIVE COMPONENT THEREBY SECURING TUFTS IN THE STRUCTURE.

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