US2448032A - Textile fabric - Google Patents

Description

Aug.. 31, 1941s.v Es, KENNEDY 2,448,032

TEXTILE wants Filed Juna 2e.l 1944- 2 sheets-shut 1 a @A o/a FQfQ ufwcy Osc/LLA Tol? ATTORNEY Filed June 28, 1944 2 Sheets-Sheet 2 f ;klwfmmwwhw z: @wa iX ....l. llbl \\\|s .i Ov i WW\ m., Q N S 0 S @N \J\ i MH- il Q 1 c l s QN O N uw ATTORNEY rmnea Aq. 31,

TEXTILE FABRIC d Edgar S. Kennedy, Wayne, Pa., aalignor to AmericanViscoaeCo 11m-ation, corporation of Delaware Wilmington, Del., a

Application June 28, 1944, Serial No.n42,459

2 Claims. (Cl. iid-172) This invention relates to knitted fabrics comprising thermoplastic fibers, and to methods and apparatus for the production thereof, and it is the primary object of this invention to produce knitted fabrics whose seivages are substantially free of curl and have little or no tendency to dev velop a curled condition during the ordinary process of finishing.

While the invention is applicable generally to flat knitted fabrics `whose edges have a tendency to curl because of liveliness of twist, that is, any

plane knit fabric, it is of special advantage as applied to warp knit fabrics, and its application will be described with yreference to the manufacture of a tricot or warp knit fabric. Such curling of the edges causes great difiiculty in stitching the edges together to form a tubepreparatory to dyeing and finishing processes. If dyeing and finishing is to be performed by passing the fabric through a tenter frame, either clip or pin, there is diiiiculty in properly feeding the fabric to the tenter or the curled edge portions thereof must be wasted. In either system, it has been customary to cut the curled selvage from the fabric as waste at thefstage of garment cutting. As this curled edge frequently amounts to a width of as much as an inch or two and sometimes more,

it can ybe seen that such waste has been. substantial. l

Generally, my invention involves the application of a substantially dry internal heat by means of a high frequencyelectric field to the fabric edges as it proceeds from the knitting needles to a take-up roller or mandrel. At this time, the fabric is under tension and by applying heat close to theneedles therels littleopportunity for it to manifest its,tendency .to curl and it is travelling slowly so that precise control of thevv heating. eect upon the fabric edges can be readily exercised. ByfjJ pplying dry internal heat, there is substantially'hp' tendency for the disposition of the ilbers l in"the` individual yarns of the fabric to become:

alteredby surface tension, or adhesive eilects exertedby. the. presence of moisture alone or. in

conjunction with sizingmateriais carried byl or within the yarns. In addition, the thermoplasticv fibers exposed on the surface ofthe yarns do not suffer any serious deformation and loss of fiber identity4 while those within are brought to sumcient temperature to relieve internal flberstresses and tobecome adhesive to bind fibers in the yarns.j -E-In-this manner, a-uniform activation of the thermoplastic fibers is obtained. throughout the fabric,and the setting of the fabric edges to control curling is obtainedv without undue loss of pliability, softness, porosity, handle and the like.

The knit fabrics may consist entirely of heatactivatable fibers or may comprise them in any desired substantial proportion together with nonactivatable fibers. By heat-activatable" is meant those fibers which are capable of being rendered adhesive upon the application of heat. By non-activatable or non-adhesive fibers is meant any which are not rendered adhesive by the treatment used in activating the heatactivatable fibers.

The potentially adhesive fibers maybe composedI of a wide variety of materials, and may comprise any material capable of being formed into fibers which havev an inherentv tackiness upon heating to temperatures below that at which the non-activatable fibers are damaged or rendered tacky and which are non-tacky at room temperature. Examples of the heat-activatable fibers include suchl thermoplastic fibers or filaments as those of cellulose acetate or other cellulose esters and .ethers or mixed esters, suchas cellu- 'lose acetate propionate or cellulose acetate alcohol-polybasic acid resinspdrying oil modifled alkyd resins, resins formed from acrylic acid, its homologues and their derivatives, sulfur-oleflne resins, resins formed from'dicarboxylic acids y and diamines (nylon type) synthetic rubbers and rubber substitutes, herein called resins," such for .example as polymerized butadiene, oleiine polysulfides, -isobutylene polymers, chloroprene polymers; and fibers formed from a resin comprising the productof copolymerizing two or more resins, such ascopolymers of vinyl halide and vinyl ace- -tate,icopolymers of vinyl halide and an acrylic acid derivative; and also a mixture of resins, such as a 4mixture of vinyl resins and acrylic acid resinsor methacrylic acid resins, a mixture of polyoleflne resins and phenol-aldehyde resins, or a mixture of two or more resins from the different classes just named. There may be employed also fibersmade from rubber latex, crepe rubber,

rgutta. percha, balata, and the like.

1 Further, the potentially adhesive fibers may be mixtures of the cellulose derivatives with resins or rubber, such for example, as a mixture of cellulcse nitrate and an acrylic acid resin, or a mixture of benzyl cellulose and a vinyl resin, or a mixture of ethyl cellulose and shellac.

Y A preferred class of vinyl resins from which the fibers may be formed are the copolymers of vinyl chloride with vinyl acetate or vinyl cyanide and after-chlorinated copolymers of vinyl chloride and vinyl acetate.

The resins above mentioned may be classifiedv used are wood pulp fibers, cotton, flax, jute,

kapok, silk, and the like, or synthetic fibers or filaments of cellulosic composition, such as a cellulose or regenerated cellulose, cellulose derivatives, such as cellulose esters, mixed cellulose esters, cellulose ethers, mixed cellulose esteri ethers, mixed cellulose ethers, cellulose hydroxyethers, cellulose carboxy-ethers, cellulose etherxanthates, cellulose xanthofatty acids, cellulose thiourethanes; natural and synthetic rubber and derivatives thereof; alignic acid, gelatine, casein;

mineral. fibers or filaments such as spun glass, asbestos, mineral wool and the like; fibers or filaments made of natural and synthetic resins which should be of such type that they 'are not rendered tacky when the potentially adhesive fibers are rendered tacky by heating; and the bers made by slitting, cutting or shredding non-fibrous films, such as waste Cellophane.

Prior to the knitting or even as they are fed to the needles of the knitting machine, the yarns may be treated with sizings or they may be moistened. They may carry a sizing or a lubricant, or some other conditioning agent applied at some earlier stage of fabrication, and the sized yarns may be moistened as they proceed to the knitting needles. Again the selvages of the fabric may be moistened very shortly after leaving its line of formation at the knitting needles but prior to entering the heating device. Such moistening may be effected by water alone, or when the yarns are of extremely low conductivity because of an unsized condition. those from which the fabric edges are formed may be moistened by a dilute electrolyte, such as a dilute salt solution to increase the conductivity of the edge portions. This may advantageously be applied in the case of hydrophobic vinyl resin yarns. However, many materials, such as cellulose acetate, from which the yarns may be formed are sufficiently hygroscopic so that their moisture content when in equilibrium with lubricant, such as ethylene oxide condensation product of sorbitan oleates, maybe knitv in the dry condition, and have their selvages treated to prevent curling. In addition, the activatable fibers themselves may be so produced artincially in the ilrst instance as to be constituted of or contain a heat-conductive material. Buch a material such as graphite or metallic powders may be distributed in this manner more or less homogeneously throughout the ber or lament mass or it may be localized in the core of the fiber or filament or upon the surface thereof.

Any suitable h igh frequency oscillator may be employed for the purposes of the invention and the voltage at which it is operated may be varied widely within the limits determined by the development of a corona discharge between the electrodes. A frequency of from ten to thirty megacycles per second is entirely satisfactory, the particular frequency employed in any. particular case depending upon the allowable voltage and the amount of power desired.

Pressure may be applied to the fabric edge while it is being subjected to the high frequency electric -fleld and such pressure may advantageouslybe applied through the medium of the electrodes themselves, such electrodes being insulated in such case. While the application of pressure is by no means necessary, it generally serves to more reliably and effectively control the extent of adherence between the adhesive and non-adhesive laments in the product.

The operating characteristics of the oscillator system including power, voltage, relationship of fabric speed to electrode area, conductivity of yarns and pressure of electrodes are so correlated as to produce the desired heating effect which depends upon the particular thermoplastic material in the fabric. Thus, a temperature of 250 F, is effective upon a cellulose acetate fabric in equilibrium with the atmosphere while a temperature of F. is effective for Vinyon.

An illustrative arrangement is shown inthe Figure 2 is a top view of this embodiment ati right angles to Figure 1;

Figure 3 is a modification looking in the longitudinal direction of the fabric;

Figure 4 is a view of another modification looking in the direction of the fabric; and

Figure 5 is a view illustrating the application of the 'invention to a full-fashioned hosiery. machine.

With' reference first to Figures 1 and 2, a plurality of the yarns 2 and 3 supplied by warp beams (not shown) are shown proceeding to guides 4 and 5, then to the needles 6 and sinkers 1 associated operatively with the presser bar 8 to perform the knitting cycle repeatedly to form the4 fabric 9 which then passes under tension beneath a roll IIJ to the cloth take-up beam H driven in conventional fashion. Along each edge of the fabric, there are disposed upper and lower electrodes I 2 and I3 respectively which are connected to opposite terminals of a high frequency oscillator by means of the leads I4 and i5.

The lower electrodes are stationary and whilel the upper electrodes may also be fixed, it is preferable that they be resiliently pressed againstthe fabric, such as by springs I6.

In Figure 3, a modified arrangement of electrodes is shown in which the fabric passes between opposed electrodes 2| which may or may not be pressed against the fabric, but are at least in close proximity thereto. A third electrode 22 (which may or may not be arcuate as shown) is arranged adjacent the edge of the fabric and is that to which both the other electrodes are connected. If desired, one or the other of the electrodes 2| may be omitted. Electrode 2| is spaced4 so that its center line runs approximately along the inner limit of the portion of the edge which ordinarily curls up.

In Figure 4 a lower electrode 23 is spaced inwardly from the edge of the fabric and an upper electrode 24 connected to an opposite pole of the oscilla-tor 25. This arrangement in which the electrodes are offset from each other on opposite sides of the fabric, sets up eddy currents across the width of the fabric extending between the two electrodes `and is a preferred arrangement.

In Figure 5, there is shown a flat knitting machine unit, ysuch as in use for the production of full-fashioned hosiery comprising the supporting frame 26 and the narrowing frame arms 21 which is rocked in conventional fashion in response to a conventional narrowing cam and associated linkage and carries thebars and V29 which in turn carry `the fingers 30 and 3| and are moved. longitudinally to narrow or Widen `the fabric by conventional con-trolling mechanism. As the fabric proceeds from the needles 32 to the takeup 33, its selvage regions pass between corresponding pairs of electrodes 34 and 35 connected to opposite poles 36 and y3l of a radio frequency oscillator 39. Each pair of electrodes is carried by an arm 39 which is slidably mounted on a guide 40 secured to the frame 29. As shown the arm 39 and guide 40 have a dovetail shaped connection. Arm 39 has an upwardly extending branchprovided with an arcuate slot 4| through which a pin 42 secured to a lateral projection 43 on the bar 29 extends. A washer 44 heid in place on pin 42 by 'a cotter pin 45 provides a positive connection for imparting the longitudinal movement of -the narrowing bar 29 to the arm 39 carrying the electrodes while the arcuate slot permits the rocking movement of the bar 43. A similar connection (4|a and 42a) is provided between the pair of electrodes at Ithe other side of the fabric and the narrowing bar 28. In this manner, a. constant width strip of fabric adjacent each selvage is treatedto prevent curling regardless of the position of the selvages during knitting when narrowing or widening occur. The upper electrodes 35 may be pivot/ally mounted as at 4l to permit them to be swung out of the way during the operation of turning the welt.

The description herein is intended to be illustrati've. only and it is to be understood that changes' land variations. may be made without'.Y departing' from the spirit and scope of the invention as: defined by the appended'claims.

Iclaimz.

1, A fiat. plain knit fabric formed of yarns comprising thermoplastic fibers, fibers in a narrow portion only thereof along each of the longituf dinal selvages of the fabric being bonded by in herent -thermal Itackiness of thermoplastic fibers therein tov produce a stable, non-curling condition of the yarns without undue loss of pliability, softness,I porosity, handle and Ithe like.

2. A fiat wai-.p knit fabric formed of yarns comprising thermoplastic fibers, fibers ,in a narrow portion only thereof along each of the longitudi`-. n al selvages of the fabric being bonded by inhercnt thermal tackiness of thermoplastic fibers therein to. produce a stable, non-curling condi tion of theyarns without undue loss of pliability, softness, porosity, handle and the like.

EDGAR S. KENNEDY.

REFERENCES CITED The following references are of record in the file if this patent:

UNITED STATES PATENTS Number Name Date 745,028 Toles Nov. 24, 1903 1,758,665 Hofner May 13, 1930 1,773,968 Dreyfus Aug. 26, 1930 1,802,634 Dreyfus Apr. 28, 1931 1,837,616 Greenwald Dec. 22, 1931 1,854,693 Dickie et al. Apr. 9, 1932 2,064,710 Wirth Dec. 15, 1936 2,072,095 Cohn Mar. 2, 1937 2,133,935 Johnson Oct. 18, 1938 2,157,116 Carothers May 9, 1939 2,301,703 Humphreys Nov. 10, 1942 2,325,652 Bierworth Allg. 3, 1943 2,333,618 Strauss Nov. 2, 1943 2,373,374 Bierwor-th Apr. 10, 1946 FoEIGN PATENTS Number Country Date 293,858 Great Britain Oct. 25, 1929 554,383 Great Britain July 1, 1943 Certificate of Correction Patent No. 2,448,082. August 31, 1948. EDGAR S. KENNEDY It is hereby certified that errors appear n the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 12, for the Word plane read plain; column 3, line 44, for Cellophane read cellophane;

and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of June, A. D. 1949.

THOMAS F. MURPHY,

Assistant 'ommz'ssz'oner of Patents.

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