US2991536A - Felted fabric and process for producing - Google Patents

Description

July 11, 1961 G. i.. Mou-:R 2,991,535

FELTED FABRIC AND PROCESS FOR PRODUCING Filed March 10. 1954 i u mgm n INVENTOR GLeSZz'eMUZeI BY @mi )gef/ww ATTORNEY United States Patent O 2,991,536 FELTED FABRIC AND PROCESS FOR PRODUCING George Leslie Moler, Wilmington, Del., assignor to E. I.

du Pont de Nemours and Company, Wilmington, Del.,

a corporation of Delaware Filed Mar. 10, 1954, Ser. No. 415,196 6 Claims. (cl. zzz-72.2)

This invention relates to a process of finishing fabrics and products produced thereby. More particularly it is concerned with a process for felting fabrics and with a novel fabric made from a yarn spun from epithelialless ber.

By t-he term epithelialless ber as used herein is meant a staple or general ber of natural or synthetic origin which lacks the epithelial scales of wool. Thus a yarn spun from epithelialless ber is a yarn composed essentially of bers free from scales.

The felting phenomenon, i.e., the displacement and intermingling of the bers in a woven or knitted fabric, has been known to be possible only with fabric containing epithelial bers such as wool. The felting procedure has involved intermittent mechanical compression as by beating or twisting and shrinking under the inuence of heat and moisture. At least partly due to the epithelial nature of the individual ber the intermittent stimuli cause the ber in the yarn to creep toward its root end. This creeping results in a random ber arrangement within the fabric which may hide the weave pattern.

It is an object of the present invention to provide a novel felting process.

Another object is to provide a process for the felting of a fabric produced from a yarn spun from epithelialless ber.

Another object is to provide a process for the felting of a fabric produced from a yarn spun from a man-made ber.

A further object is to provide a novel felted fabric produced from a yarn spun from epithelialless ber.

l These and other objects will become apparent in the course of the following specification and claims.

In accordance with the present invention woven fabric made up entirely of woven yarns and knitted fabric made up entirely of knitted yarns, the yarn bers being composed of at least about 80% of bers free from scales, is felted by a multiple needling. By multiple needling is meant subjecting the fabric to recurrent piercing and withdrawing of a needle to be described hereinafter with the needle and fabric in substantially xed lateral relationship during penetration, until migration of bers into adjacent or crossing yarns within the weave is attained.

The invention will be more readily understood by reference to the drawing.

FIGURE 1 is an illustration of an open plain weave of a low twist, high denier yarn.

FIGURE 2 illustrates the fabric of FIGURE 1 after fulling in accordance with the present invention.

FIGURE 3 illustrates a relatively tight weave as compared with that of FIGURE 1 wherein uneven spacing of the warp yarn has occurred.

FIGURE 4 illustrates the effect obtained upon subjecting the fabric of FIGURE 3 to the process of the present invention.

v'FIGURE 5 is a side view of a fabric passing under a needle bank.

The following examples are cited to illustrate the invention. They are not intended to limit it in any manner.

Example I A yarn is spun in the woolen system from polyethylene terephthalate staple, an epithelialless ber. The ber is 7 denier per lament and 21/2 inches long. A 3-ply cord Z twisted 3 times per inch of approximately 12,000 total denier is formed from the yarn. A plain weave fabric having 7 ends per inch and 7 picks per inch 1s woven from this cord. It is shown in FIGURE l. A sample 20 inches wide is fed into a standard needle loom, such as that made by the James Hunter Machine Company of North Adams, Massachusetts. This loom is 36" wide and has a bank of 1440 equidistantly spaced steel needles. These needles, a preferred type, are prepared by etching standard size No. 25 needles (purchased from The Torrington `Company of Torrington, Connecticut, and commonly designated as l5 x 18 x 25 x 31/2, regular barb) for two 31/2 hour periods by immersion in concentrated hydrochloric acid (38% in water). Before use they are washed and dried. The etching removes the sharp protrusions of the barbs and leaves notches. The needle board is adjusted abover the fabric so that the notches penetrate through the fabric in each stroke of the needle-bank reciprocation. The bank is raised and lowered 25-0 times per minute. The fabric is moved past the needles 0.285 inch at each cycle (a complete lowering and subsequent raising). The needled fabric is re-fed to the loom 49 times. It is turned over (i.e. reversed by a 180 rotation on its long axis) on each feeding. The needles penetrate the fabric approximately 7,000 times per square inch in the 50 passes through the loom. The needled fabric as shown in FIGURE 2 has the appearance of being tightly woven. It has a smoother, nappier surface, and exhibits increased body over the original sample. The fabric shrinks about 10% in each direction while the yarn diameter is increased sufciently to close the openings which result from Weaving. When a single yarn is pulled from an edge of the fabric, it tends to be constrained due to its brous interconnection with neighboring and crossing yarns as illustrated in FIGURE 2. This brous interconnection is the result of ber migration which has occurred to bers in adjacent yarns as a result of the needle felting. The needled fabric is especially useful as a lter medium for dilute alkaline solutions because of its high resistance to abrasion and chemical attack.

Example II A Shetland tweed type of fabric with a 2 x 2 twill construction and having a weave count of 32 x 30 is woven from a yarn containing a stock blend of 20% wool and 3 denier, 21/2 inch length polyacrylonitrile staple. The ber is spun into an 18/2 cotton count yarn. 'The singles have a Z twist of l1 turns per inch and are plyed with an S twist of l0 turns per inch. A portion of the yarn is dyed brown before weaving, so that the woven fabric consists of a pattern of brown and white. A sample of this fabric 20 inches wide is fed through a standard needle loom equipped and operated as described in Example I except that the fabric is fed through theloom only 25 times. This produces a total needling of about 3,500 times per square inch of fabric surface. The needled fabric possesses more covering power, is softer and has more nap than the original sample. It is also bul'kier, its thickness having increased from 0.026 inch to 0.032 inch. The intermigration of colored and white bers produces a pleasant blending which tones down the sharp pattern contrasts.

Example III The Shetland tweed of Example I'I is subjected to 4'0 passes in the loom of Example I, the needles being round in cross-section and having a imaximum diameter of 0.035 inch on their working section. The vertical oscillation of the needle board is so adjusted that the needle passes through the fabric. This is a penetration of 5600A times per square inch. The needled fabric is similar in appearance to that produced in Example II.

Example IV A womans sweater is knitted on a 12- cut circular knitting machine from a yarn of polyacrylonitrile staple. The ber is spun into a 2/24 worsted count yarn from 3 denier staple, 21/2" long. The singles are twisted 10 turns Z to the inch. The ply contains 6% turns S to the inch. The sweater is dyed yellow. It is then fed to the needle loom as equipped and operated in Example I for a total of 28 passes. The sweater is turned inside out after each pass. This is a total needling of about 3800 times per square inch. The covering power of the needled sweater is increased so that whereas when ultra violet light is directed at the samples the original sweater transmits 6.3% of the light while the needled sweater transmits only 0.4% as recorded onV a photoelectric cell. The needled sweater is felted despite the fact that the yarn from which it is knitted is spun from epithelialless staple. it has a softer hand, greater bulk and is less sleazy as compared with its condition before needling.

Example V A plain woven fabric is made with a filling of a 5000 total denier 2 ply nylon yarn (spun from 6 denier staple 2V2 inches long, the plies containing 7 turns per inch) and a warp of an 8000 total denier 2 ply polyethylene terephthalate -yarn (spun from 6 denier staple Z/z inches long, the plies containing turns per inch). The ends of the fabric are joined by interweaving to form an endless belt. The fabric is teaseled on one side. Because of the nature of the weave, irregularity in the spacing of the polyethylene terephthalate warp occurs. The elect is illustrated in FIGURE 3. The fabric is fed into the needle loom of Example I. It is passed through the loom 25 times with the needles always entering the teaseled side. A total needling of about 3500 times per square inch is obtained. The needled fabric as shown in FIGURE 4 exhibits equal spacing of yarns in both the warp and the filling. irregularity of weave as existed in the original sample is often encountered in preparing leno and similar open-weave fabrics as Well as open-knit fabrics. As a result of the needle-punching operation, the irregularly spaced warp yarns migrate, i.e. the fabric is felted, to produce a regular weave pattern without disturbing the regular pattern of the filling yarns. It is also observed that the needling improves the surface smoothness on the unteaseled side by making the fabric more nappy and by increasing the diameter of both warp and filling yarns. The surface uniformity and body of such a fabric render it particularly useful as a papermakers felt since it contains insuiiicient pattern to mark the paper. The example illustrates a needle felted fabric wherein different yarns, both spun from epithelialless staple, are employed as warp and filling.

Example VI A typical woven woolen suiting fabric of 100% Wool is fed to the needle loom equipped as described in Example I. It is subjected to about 4,000 needlings per square inch. Instead of passing the fabric repeatedly through, it is held in the loom for about 5 minutes. The needled fabric shows improved covering power over the junnccdled sample by virtue of the felting. In addition the thickness of the fabric increases from 0.091 inch to 0.127 inch thereby increasing the bulk.

Example VII The loom of Example I is equipped with unetched standard size No. 25 needles. The process of Example VI is repeated, the barbs passing through the fabric on each penetration cycle. A multiple rending of the fabric occurs without felting.

. 4 Example VIII The needling technique of Example VI is applied to a 2 x 2 twill. The yarn which has Ian 8 turn per inch Z twist is polyester (polyethylene glycol terephthalate) spun from a 2 inch, 2.4 denier staple to an 8/1 cotton count. The equipment of Example I is employed. However the needle board is so adjusted that the needle notches do not enter the fabric surface. Thus the needling is performed with the smooth surface of an etched needle of smaller diameter. About 1700 needlings per square inch are made. Observations as to count, bulk `and thickness follow:

Bulk Thickness (cm.) Weave Count A.S.T.M.1 B.S.l.2 A.S.T.M. B.S.I.

Control. 58 x 40 2. 41 3. 72 0.094 0. 145 Nesdled- 58 x 42 2. 60 3. 88 0.104 0.155

i 3.4 pounds/ln?.

A liber migration due to felting resulting in increased covering power is noted.

Example IX A yarn of polyacrylonitrilc ber having a cotton count of 42/2 is spun from staple of which half is 1.5 denier, .l.5 inch length and half is 4.5 denier, 2.5 inch length. The yarn is given a Z twist of 7 turns per inch. It is woven into a 2 x 2 twill. The fabric is subjected to 1 As in Example VIII.

Improved covering power is observed due to ber migration.

The fabric may be needled in accordance with the present invention on one or both sides, singly or in multilayers. In multilayer treatment it is desirable to separate the layers at intervals to prevent vertical interlocking and achieve optimum results. It is not necessary that the entire fabric be subjected to the needling technique. Thus a narrow edging can be applied to a weave in accordance with the present invention to prevent unravelling. Furthermore the needling technique can be employed to create novel and artistic fabric designs and. effects. The process is particularly valuable in making endless belts by joining, i.e. an interweaving of two ends of the same fabric followed by felting to strengthen the join. Such a fabric can be used under tension as for instance as a papermakers felt.

The cross-sectional shape of the needle is not critical. It may have a round, at, elliptical, square, rectangular, hexagonal, triangular, or the like, cross-section. The end must be sufficiently pointed and the diameter suiciently small to permit piercing of the fabric Without rending of the yarn structure. The needle from which the needle used in Example I is prepared has a round sharp point increasing to an equilateral triangular cross-section. Before etching the triangular cross-section has an effective altitude of 39 mils, and contains 9 barbs, staggered evenly, 3 on an edge, the first barb being about 0.25 inch from the tip while the last is l inch from the tip. The working end of the needle is about 1.1 inches in length. It is preferredthat the Working end length be sufficient to at least pass completely through the fabric thickness. However, some felting at the surface can be accomplished with less than complete penetration. The maximum permissible needle diameter (which may vary along the shank) before rending occurs will depend primarily upon the nature of the yarn from which the fabric is woven. Usually needles having a cross-sectional dimension of about 40 mils give satisfactory results. Needles of smaller diameter are preferred. Such needles of small diameter can be obtained by dissolving away (etching) fine comunercially available needles in acid. The lower limit upon needle diameter is governed solely by the needle strength required. Satisfactory results are obtained with a smooth surface needle. It is preferred however to employ a needle with a notched surface. The preferred needle is described in detail in United States Application 427,465, filed May 4, 1954, in the name of Herbert G. Lauterbach. That application issued as U.S. Patent No. 2,857,650, on October 28, 1958. These may be conveniently prepared by etching barbed needles. A barbed needle, etched until its barbs are removed, leaving notches, has been found eminently suited. Such needles may be prepared by etching a high quality hardened steel needle in acid. The period required to remove the barbs will depend upon the needle diameter, the size of the barbs, the acid strength and the like. As a guide, the needles of Example i are preferably etched with hydrochloric acid (38% in water) for at least about 5 hours before the barbs are removed. Etching for a longer period as in the example, reduces the overall needle diameter. The deleterious effect of barbed needles is demonstrated in Example VII above.

The fabrics to which the process of this invention may be applied comp-rise those knitted or woven from yarns (preferably those spun from staple) of natural fibers (eg. wool, mohair, cotton, fur, hair, jute, ramie, hemp, silk, sisal, regenerated cellulose, asbestos, protein, glass, and the like), or synthetic `fibers (e.g. cellulose acetate, polyesters such as polyethylene glycol terephthalate, polyamides such as polyhexamethylene adipamide, and polycaproclactam, polytetrauoroethylene, polyvinyl fibers such as polyacrylonitrile and copolymers including terpolymers of acrylonitrile with vinyl pyrolidone, vinyl chloride, vinyl acetate, vinyl pyridine, or other monomers, copolymers of vinyl chloride and vinyl acetate, copolymers of vinylidene chloride and vinyl chloride, `and the like); or they may be blends of natural and/ or synthetic bers, including stock blends, end-and-end blends, pickand-pck blends, ply blends, and blends wherein the warp and filling yarns may be the same or different, natnral and/or synthetic and/or a blend of natural and synthetic fibers.

Fabrics subjected to the needling of the present invention may be finished by teaseling, brushing or the like either before or after the step of needling. Where the nature of the fiber is such as to permit chemical or thermal shrinkage, a needling step may be performed prior to and/ or after shrinking. For example, a fabric woven from polyethylene terephthalate fibers having an inherent shrinkage in boiling water of in length may be needled followed by shrinking. Where a nap is raised prior to the needling, the needling step may cause a decrease in bulk, especially if the needle is introduced into the surface bearing the nap.

While it is illustrated by Example VI above that the needle felting process of the present invention is applicable to fabrics made from wool yarn, it is particularly valuable in its application to fabrics from yarn spun from epithelialless fiber as defined hereinbefore. Thus it is possible to produce an entire novel class of felted fabrics from both natural and synthetic yarns.

The amount of needling required to attain the felting phenomenon will vary with the denier of the yarn, the size of the staple from which the yarn is spun, the twist of the yarn, the tightness of the woven pattern, the character of the needles employed and the like. In general the needling is continued until a visible migration occurs. A simple test to indicate migration in a Woven fabric is by attempting to pull away an end warp yarn. If felting has occurred, a web of minute fibers will be visible between the yarn pulled away and the body of the fabric. In general, fabrics from yarns of longer staple and looser twist will tend to needle felt more readily under any set of conditions. While no exact limits can be set due to the many variables, a needling of at least about 1500 penetrations per square inch is considered a minimum for most fabrics. Many more penetrations can be made and in fact are often preferred. Neither needle speed nor length has been observed to have any critical effect.

Among the effects which may be obtained by the process of the present invention are the removal of fabric wrinkles, the improvement of fabric hand, increases in fabric bulk, covering power, stiffness, body, the improvement of fabric uniformity, surface levelness and nap. The process permits fabrics of wool yarn to be needle felted while being increased in bulk. It provides a method of felting fabrics made from yarn spun from manmade fibers. It permits the strengthening of joins to an extent impossible to attain by interweaving.

Typical examples of industrial uses for the products of this invention include filter fabrics for both gas and liquid filtrations, papermakers felts, polishing fabrics, blankets, conveyor beltings, roll coverings, Sanforizing blankets, upholstery fabrics, draperies, boot linings and the like. Examples of household uses are apparel, such as sweaters, suitings, hosiery, overcoatings, underwear, shirting and blouse fabrics, headwear and the like.

Many modifications will be apparent to those skilled in ythe art from a reading of the above without a departure from the inventive concept.

What is claimed is:

il. The method of making a novel fabric having physical properties and appearance similar to felted wool fabric which comprises subjecting a fabric selected from the group consisting of fabrics made up entirely of woven yarns and fabrics made up entirely of knitted yarns, the yarn fibers being composed of at least about of staple fibers free from scales, to a multiple needling treatment for moving a substantial portion of yarn fibers loosely into interlocking engagement with fibers of adjacent yarns throughout the thickness of the fabric, the needle and fabric being maintained in substantially fixed lateral relationship during penetration by the needle to produce a fabric in which intermingied and interlocked fibers provide improved fabric uniformity, covering power and stiffness.

2. The process defined in claim l wherein the multiple needling treatment is accomplished with notched needles from which sharp protrusions have been removed by etching.

3. The process defined in claim 2 wherein the multiple needling treatment comprises at least about 1500 needle penetrations per square inch of fabric.

4. The process defined in claim l wherein edges of Woven fabric are joined by interweaving the yarn material and the joined fabric is then subjected to the treatment to produce a uniform fabric.

5. The process defined in claim l wherein said yarn material is composed of a blend of natural and synthetic fibers.

6. A novel fabric selected from the group consisting of fabrics made up entirely of woven yarns and fabrics made up entirely of knitted yarns, the yarn fibers being composed of at least about 80% of staple fibers free from scales, a substantial portion of the yarn fibers being intermingled in loosely interlocking engagement with fibers of adjacent yarns throughout the thickness of the fabric to provide characteristics of felted wool fabric in the fabric solely by random migration of yarn fibers.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Heaton Feb. 12, 1901 Veit Jan. 14, 1913 Walsh et a1. July 11, 1939 Foster Dec. 1, 1942 Chagnon July 15, 1947 Francis j .r. r Oct. 31, 1950 Gates Mar. 4, 1,952 Bergvlund 4- Mar. 18, 1952 Bloch Feb. 8, 1955 FOREIGN PATENTS Canada July 2,5, 1950

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