US2669502A

US2669502A - Method for dyeing and presetting tricot fabrics

Info

Publication number: US2669502A
Application number: US236912A
Authority: US
Inventors: Leslie L Walmsley
Original assignee: American Viscose Corp
Current assignee: Akzo Nobel UK PLC
Priority date: 1951-07-16
Filing date: 1951-07-16
Publication date: 1954-02-16
Anticipated expiration: 1971-02-16

Description

Feb. 16, 1954 WALMSLEY 2,669,502

METHOD FOR DYEING AND PRESETTINGTRICOT FABRICS Filed July 16, 1951 INVENTOR. L-ESL/E L. WALMSLEY BY W Arrai v.

Patented Feb. 16, 1954 OFFICE METHOD FOR DYEING AND PRESETTHNG TRICOT FABRICS Leslie L. Walmsley, Ridley-Park, Pa... assignor to American Viscose Corporation,

Wilmington,

DcL, a corporation of Delaware Application July 16, 1951, Serial No. 236,912

(Cl. S 17) 3 Claims. 1

This invention relates to a method for simultaneously dyeing and presetting, at full open width, tricot fabrics the edges of which normally tend to curl spontaneously during dyeing of the fabric.

Tricot fabrics have not been dyed at full open width heretofore because, as is wellknown, the selvages of a tricot fabric normally tend to curl or roll inwardly as much as a to 12 inches on either side of the fabric, when it is relaxed, and in order to prevent such curling during dyeing of thefabric it has been the practice to the edges of the fabric together before entering it into the dyebath. The precaution of sewing the edges together prior to dyeing a tricot fabric in .a hot dyebath has been particularly important in the case of fabrics of thermoplastic materials such as cellulose acetate since there it is necessary to avoid setting of the edges in the curled condition by the heat of the bath in order to avoid the waste of material which would result if the edges were set in the curled condition and the curled fabric hadto be cut away.

It is obvious that although dyeing the tricot fabrics in tubular condition prevents edge-rolling or curling thereof during the dyeing operation, the need for sewing the edges together and then removing the stitches after the fabric has been dyed is time-consuming and expensive.

One object of the present invention is to provide a method for dyeing a tricot fabric the edges of which tend to roll s ontaneously at full open width while simultaneously presetting the fabric in the flat. open width condition.

tendency of the edges of a tricot fabric to curl spontaneously as soon as the fabric is taken from the knitting machine is due to strains which are introduced into the fabric by looping of the yarns upon the needles duringlcnitting thereof. Since this tendency is inherent, it will. persist until the strains responsible for it are completely relieved.

Ey p-resetting-the tricot fabric as used. herein is meant that, simultaneously with dyeingthereof, the strains in the fabric which cause the edges to roll or curl spontaneously are relieved with elimination of the tendency of the edges to curl.

I have found that it is unnecessary to sew the edges of a tricot fabric together prior to dyeing it, if the dyeing is performed at full open width under conditions such that the strains responsible for the edge-rolling are permanently relieved. This is acccmp shed, in accordance with the invention, by uncurling the edges of the tricot fabric having curled edges and which is to be dyed, then passing the uncurled fabric longitudinally through a dyebath which is also a setting or stabilizing bath for the fabric under conditions such that curling of the fabric edges is prevented until the strains in the fabric are relaxed, after which the edges will no longer curl spontaneously to any appreciable extent. During relaxation of the strains in the dyebath, the fabric, which is maintained in flat condition, picks up the dye from the bath and the fabric withdrawn from the bath is dyed to the desired color and depth of shade and stabilized in the substantially fiat condition.

In practicing the invention, the tricotfabric in the dry condition and having curled edges which. is to be dyed is advanced continuously to and along a path through the dyeing and setting bath under a tension sufficient only to draw. the fabric through the bath. and as thefabric a'dvances to the path through the bath the edges thereof are uncurled, the fabricbein'g passed into the path in the uncurled condition and held in that condition until it is dyed and stabilized or preset.

The fabric may be dyed and preset concurrently withthe dyeing by passingit only once through a solution or dispersion of the selected dye in a partial solvent or swelling agent for the yarns. For example, a tricot fabric of regenerated cellulose yarns may be dyed and preset .by passing it through an aqueous solution of a direct dyestuff containing 20 to 30% ofsodium hydroxide. In the case of tricot fabrics comprising yarns of a thermoplastic materiaLihowever, it is preferred toydye and preset the fabric using a hot aqueous solution or dispersion ,of the selected dyestulf, the heat .of the bathin ducing the relaxation of the strains required for setting of the fabric in thefiat condition. .The temperature of the bath will dependbnlthe length of time required for the fabric to pass through it but generally will not be less than F. nor higher than about 25 F. below the melting point of the yarns. For example, a tricot fabric comprising yarns of commercial secondary c"ellulose acetate can be dyed and set by 'uncurling the edges of the fabric and passing the uncurled fabric through an aqueous'dispersion of one of the available water-insoluble cellulose acetate type dyestuffs (known also as nispersol' type dyes) maintained at a temperature between 180 F. and 212 F. when the time r-eauiredto pass the fabric through the bath is from 2 to 5 seconds. The bath maycontain one .orunlore of theswelling agents, for example alcohol, which are commonly used as assistants of celluloseacetate. Also, substances Which-pen mit the use of higher operating temperatures, 1. .e. substances which increase the boilinggpoint of the bath may be used, and may be desirable in dyeing and presetting tricot fabrics of nylon or the like. Further, the dyeing and setting bath may contain small amounts of finishing or lubricating agents for the fabric, or such agents be added to a cold water bath through which the dyed and preset fabric is passed after it emerges from the dyeing and presetting bath.

The conditions of the treatment, including the concentration of the dyestuff in the bath and the temperature of the bath, are selected taking into account the shade it is desired to dye the fabric, the thickness of the fabric, the length of the bath, and the fact that the rate at which the fabric is withdrawn from the bath must be correlated with the rate at which it is fed into the bath to insure free passage of the fabric through the bath without placing it under a tension which would inhibit relaxation of the strains therein.

Any suitable uncurling device may be used to uncurl the edges of the fabric as it passes into the dyeing and presetting bath. However, the use of liquid jets or sprays for uncurling the fabric is to be avoided in order to prevent the dyeing variations which would result from wetting of portions of the fabric prior to its introduction into the dispersion of the dyestuff.

It is essential to the successful practice of the invention that the uncurling means is so lo cated with respect to the dyeing and presetting bath that the fabric enters the path through the bath inthe fiat, uncurled condition, and that the fabric be prevented from recurling in the bath before the strains responsible for the curling are relieved.

The fabric may be prevented from recurling after it passes into the bath by providing a mem her or members having a width at least as great as the width of the fabric and which define the path for the fabric and exert downward pressure on the fabric in the dyebath across the entire width thereof to prevent recurling of the edges, to keep the fabric submerged, and to assist in guiding it along a path through the bath consisting of an initial portion downwardly inclined from the fabric entrance and extending to a depth of at least two inches below the top surface of the dyebath, a generally horizontal portion extending from the initial portion along a substantially straight line at a depth of at least two inches below the top surface of the dyebath, and an upwardly inclined portion extending from the generally horizontal portion out of the dyebath. Thus, the uncurled fabric may be passed under a guide plate having a width at least as great as the width of the fabric, which is supported generally horizontally in and below the level of the bath, and the lower surface of which defines the upper side of the path for the fabric and prevents recurling thereof. Or two plates or equivalents thereof may be generally horizontally supported one above the other in spaced relation in the bath to define a path for the fabric therebetween having a depth greater than the thickness of the fabric but less than the depth which would permit curling of the fabric edges.

In the attached drawing,

Figure l is a view in perspective of apparatus for carrying out one preferred embodiment of the invention;

Figure 2 is a section taken on line 11-11 of Fig. 1; and

Figure 3 is a cross-section through the curled 4 selvage of a tricot fabric showing the coils in the edge-roll or edge-curl thereof.

Referring to the drawing, there is shown a vessel 2 provided with a removable cover 2a and containing a dyeing and presetting bath for the tricot fabric. Two guide plates 3 and 4 are supported generally horizontally in the vessel as shown. The plates, which in a specific embodiment of the invention are each 12 inches wider than the fabric, are disposed one above the other, in spaced relation, to provide a guideway or tunnel 5 of substantially uniform cross-section for the fabric below the level of the liquid. The distance between the adjacent, smooth fiat surfaces of the plates is sufficient to permit free passage of the fabric between them, but is insufficient to permit curling or rolling of the fabric edges. This distance may be varied, depending on the thickness of the fabric. The smooth lower face of the upper plate 3 defines the upper side of the path for the fabric through the bath; the smooth upper surface of the lower plate 4 defines the lower side of the path for the fabrics. The opposite ends of plate 3 are curved or flared upwardly, and the opposite ends of plate 4 are curved or flared downwardly to facilitate feeding of the fabric to the space between the plates and withdrawal of the fabric from the vessel, and to prevent undue tension on the fabric as it is advanced through the bath.

The dry tricot fabric having curled edges is advanced longitudinally at open width (with that face of the fabric which forms the inside face of the coils in the edge-curls facing upwardly as shown) to vessel 2 over the driven feed roll 6 downwardly over the inclined guiding and supporting surface 1, fed between the plates 3 and 4, withdrawn from vessel 2 by the driven rolls 8 and 9, a guiding roll iii being supported in the vessel ll containing cold water and supported between rolls 8 and 9. As shown, the guiding and supporting surface I is a fiat, plate-like member and both it and the guide plates 3 and 4 are made of any suitable material, preferably a polished metal such as stainless steel. Guiding surface 1 extends into vessel 2 and is fixed in inclined relation to feed roll 6 and the guideway or tunnel 5 between plates 3 and 4 so that the fabric passes from the guiding plate 7 directly into the tunnel 5.

In order to uncurl the edges of the fabric and maintain the fabric in the uncurled fiat condition until it enters the guideway 5 in which recurling is prevented by the guide plates, jets of a gaseous fluid under pressure are projected in opposite directions extending laterally outwardly from the central portion of the upper face of the fabric against the opposite edges of the fabric at successive points along the path of travel of the fabric downwardly over guiding and supporting surface i (see Fig. 2) to the guideway 5. For this purpose, as shown in the drawing, two pipes or conduits I2 and I3, each provided with a row of perforations it, are supported above and parallel to the guiding surface I on the cross-bars i5 and It which are in turn supported on the standards ll, i8 and I9, 29. Pipes I 2 and I3 are adjustable horizontally on the cross-bars l5 and It by adjustment of the clamps or brackets designated generally at 2|, and cross-bars l5 and It are adjustable vertically on the standards i1, i8 and iii, 2i respectively by adjustment of the clamps or brackets designated generally at 22. Air or other gaseous fluid under pressure is fed to pipes I2 and i3,

'7 prises the steps of continuously advancing the aforesaid fabric in the dry condition longitudinally toward a dyebath at open width downwardly over a fiat, inclined supporting surface with that face of the fabric which forms the inside face of the coils in the edge-curls facing upwardly, said dyebath comprising an aqueous dispersion of a water-insoluble cellulose acetate dyestuff and a swelling agent for cellulose acetat and being maintained at a temperature between 180 F. and 212 F., uncurling the edges of the fabric advancing to the dyebath as it approaches and immediately before it enters the dyebath by continuously projecting air jets in opposite directions extending late-rally outwardly from the central portion of the aforesaid face of the fabric against the opposite edges of the fabric while it is supported on said supporting surface, continuously drawing the thus-advanced fabric with its edges uncurled in full open width only once through the dyebath, exerting downward pressure on the fabric in the dyebath across the entire width thereof to prevent recurling of the edges and to keep the fabric submerged therein, guiding the fabric along a path therein consisting of an initial portion down wardly inclined from the fabric entrance and extending to a depth of at least two inches below the top surface of the dyebath, a generally horizontal portion extending from the initial portion along a substantially straight line at a depth of at least two inches below the top surface of the dyebath, and an upwardly inclined portion extending from the generally horizontal portion out of the dyebath, the fabric during said drawing step being under a tension sufficient only to draw the fabric through said path whereby to provide free passage of the fabric through the dyebath without placing it under a tension which would inhibit relaxation of the strains therein, and circulating the dyebath by continuously withdrawing a portion thereof adjacent the end from which the fabric is discharged and introducing the portion withdrawn adjacent the end into which the fabric enters at a plurality of points distributed the full width of the dyebath adjacent the bottom thereof.

2. A method of simultaneously dyeing and stabilizing against edge-curling a tricot fabric comprising yarns of cellulose acetate and having strains which cause the edges to curl which comprises the steps of continuously advancing the aforesaid fabric in the dry condition longitudinally toward a dyebath at open width downwardly over a inclined supporting surface with that face of the fabric which forms the inside face of the coils in the edge-curls facing upwardly, said dyebath comprising an aqueous dispersion of a water-insoluble cellulose acetate dyestuif and a swelling agent for cellulose acetate and being maintained at a temperature between 80 F. and 212 F., uncurling the edges of the fabric advancing to the dyebath as it approaches and immediately before it enters the dyebath by continuously projecting air jets in opposite directions extending laterally outwardly from the central portion of the aforesaid face of the fabric against the oppositc edges of th fabric while it is supported on said supporting surface, continuously drawing the thus-advanced fabric with its edges uncurled in full open width only once through the dyebath at a rate such that the time of passage of the fabric through the dyebath is of the order of five seconds, exerting downward pressure on the fabric-in the'dyebath across the entire width thereof to prevent recurling of the edges and to keep' the fabric submerged therein, and guiding the fabric along a path therein consisting of an initial portion downwardly inclined from the fabric en-- trance and extending to a depth of at least two inches below the top surface of the dyebath, a generally horizontal portion extending from the initial portion along a substantially straight line at a depth of at least two inches below the top surface of the dyebath, and an upwardly inclined portion extending from th generally horizontal portion out of the dyebath, the fabric during said drawing step being under a tension sufficient only to draw the fabric through said path whereby to provide free passage of the fabric through the dyebath without placing it under a tension which would inhibit relaxation of the strains therein.

3. A method of simultaneous1y dyeing and stabilizing against edge-curling a tricot fabric comprising yarns of cellulose acetate and having strains which cause the edges to curl which comprises the steps of continuously advancing the aforesaid fabric in the dry condition longitudinally toward a dyebath at open width downwardly over a flat, inclined supporting surface with that face of the fabric which forms the inside face of the coils in the edge-curls facing upwardly, said dyebath comprising an aqueous dispersion of a water-insoluble cellulose acetate dyestuff and a swelling agent for cellulose acetate and being maintained at a temperature between F. and 212 E, uncurling the edges of the fabric advancing to the dyebath as it approaches and immediately before it enters the dyebath by continuously projecting air jets in opposite directions extending laterally outwardly from the central portion of the aforesaid face of the fabric against the opposite edges of the fabric while it is supported on said supporting surface, continuously drawing the thus-advanced fabric with its edges uncurled in full open width only once through the dyebath, exerting downward pressure on the fabric in the dyebath across the entire width thereof to prevent recurling of the edges and to keep the fabric submerged therein, and guiding R the fabric along a path therein consisting of an initial portion downwardly inclined from the fabric entrance and extending to a depth of about two inches below the top surface of the dyebath, a generally horizontal portion extending from the initial portion along a substantially straight line at a depth of about two inches below the top surface of the dyebath, and an upwardly inclined portion extending from the generally horizontal portion out of the dyebath, the fabric during said drawing step being under a tension sufiicient only to draw the fabric through said path whereby to provide free passage of the fabric through the dyebath without placing it under a tension which would inhibit relaxation of the strains therein.

LESLIE L. WALMSLEY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,913,601 Leppin June 13, 1933 2,303,934 I-Ieckert Dec. 1, 1942 2,365,931 Benger Dec. 26, 19% 2,402,621 Gifford June 25, 1946 2,613,521 Walmsley Oct. 14, 1952 2,613,522 Heffelfinger Oct. 14, 1952 v OTHER REFERENCES Journal Textile Institute, page A253, May 1950. "Rayon Textile Monthly, July 1944, page 325.

Claims

1. A METHOD OF SIMULTANEOUSLY DYEING AND STABILIZING AGAINST EDGE-CURLING A TRICOT FABRIC COMPRISING YARNS OF CELLULOSE ACETATE AND HAVING STRAINS WHICH CAUSE THE EDGES TO CURL WHICH COMPRISES THE STEPS OF CONTINUOUSLY ADVANCING THE AFORESAID FABRIC IN THE DRY CONDITION LONGITUDINALLY TOWARD A DYEBATH AT OPEN WIDTH DOWNWARDLY OVER A FLAT, INCLINED SUPPORTING SURFACE WITH THAT FACE OF THE FABRIC WHICH FORMS THE INSIDE FACE OF THE COILS IN THE EDGE-CURLS FACING UPWARDLY, SAID DYEBATH COMPRISING AN AQUEOUS DISPERSION OF A WATER-INSOLUBLE CELLULOSE ACETATE DYESTUFF AND A SWELLING AGENT FOR CELLULOSE ACETATE AND BEING MAINTAINED AT A TEMPERATURE BETWEEN 180* F. AND 212* F., UNCURLING THE EDGES OF THE FABRIC ADVANCING TO THE DYEBATH AS IT APPROCHES AND IMMEDIATELY BEFORE IT ENTERS THE DYEBATH BY CONTINUOUSLY PROJECTING AIR JETS IN OPPOSITE DIRECTIONS EXTENDING LATERALLY OUTWARDLY FROM THE CENTRAL PORTION OF THE AFORESAID FACE OF THE FABRIC AGAINST THE OPPOSITE EDGES OF THE FABRIC WHILE IT IS SUPPORTED ON SAID SUPPORTING SURFACE, CONTINUOUSLY DRAWING THE THUS-ADVANCED FABRIC WITH ITS EDGES UNCURLED IN FULL OPEN WIDTH ONLY ONCE THROUGH THE DYEBATH, EXERTING DOWNWARD PRESSURE ON THE FABRIC IN THE DYEBATH ACROSS THE ENTIRE WIDTH THEREOF TO PREVENT RECURLING OF THE EDGES AND TO KEEP THE FABRIC SUBMERGED THEREIN, GUIDING THE FABRIC ALONG A PATH THEREIN CONSISTING OF AN INITAL PORTION DOWNWARDLY INCLINED FROM THE FABRIC ENTRANCE AND EXTENDING TO A DEPTH OF AT LEAST TWO INCHES BELOW THE TOP SURFACE OF THE DYEBATH, A GENERALLY HORIZONTAL PORTION EXTENDING FROM THE INITIAL PORTION ALONG A SUBSTANTIALLY STRAIGHT LINE AT A DEPTH OF AT LEAST TWO INCHES BELOW THE TOP SURFACE OF THE DYEBATH, AND AN UPWARDLY INCLINED PORTION EXTENDING FROM THE GENERALLY HORIZONTAL PORTION OUT OF THE DYEBATH, THE FABRIC DURING SAID DRAWING STEP BEING UNDER A TENSION SUFFICIENT ONLY TO DRAW THE FABRIC THROUGH SAID PATH WHEREBY TO PROVIDE FREE PASSAGE OF THE FABRIC THROUGH THE DYEBATH WITHOUT PLACING IT UNDER A TENSION WHICH WOULD INHIBIT RELAXATION OF THE STRAINS THEREIN, AND CIRCULATING THE DYEBATH BY CONTINUOUSLY WITHDRAWING A PORTION THEREOF ADJACENT THE END FROM WHICH THE FABRIC IS DISCHARGED AND INTRODUCING THE PORTION WITHDRAWN ADJACENT THE END INTO WHICH THE FABRIC ENTERS AT A PLURALITY OF POINTS DISTRIBUTED THE FULL WIDTH OF THE DYEBATH ADJACENT THE BOTTOM THEREOF.