US3309720A - Process for treating nonwoven pile fabrics - Google Patents

Description

March 21, 1967 P. M. COLE 3,3@9,72

PROCESS FOR TREATING NONWOVEN FILE FABRICS Original Filed Nov. 27, 1963 2 Sheets-Sheet 1 INVENTOR PAUL MORRiSON COLE BY S W Ema/TV /GEW P. M. COLE March 21 W67 PROCESS FOR TREATING NONWOVEN FILE FABRICS 2 Sheets-Sheet 2 Original Filed Nov. 27, 1963 I INVENTOR PAUL MORRaSON COLE BY Wm "MW United States Patent Office 33%,726 Patented Mar. 21, 1967 3,309,720 PRQCESS FOR TREATENG NON /VGVEN FILE FERBRICS Paul Morrison Cole, Carr-croft, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware Griginal application Nov. 27, 1963, Ser. No. 326,511, new Patent No. 3,262,291, dated July 27, 1966. Divided and this appiication Dec. 20, 1965, Ser. No. 514,802

4 Claims. (Cl. 8-l54) This application is a division of my copending application, S.N. 326,511, filed November 27, 1963 now US. Patent No. 3,262,291.

This invention relates to a process for dyeing fabrics, and more particularly, for the beam dyeing of nonwoven pile fabrics.

In the production of dyed woven pile fabrics such as blankets, carpets and the like, widely differing techniques are commercially employed for obtaining a satisfactory dye level. In some cases, the pile-forming fibers are dyed in the form of a low, Warp or other fibrous assembly prior to being tufted, woven or otherwise fabricated with a backing layer into the desired pile structure. In other instances the fibers are first secured to a backing and this is followed by dyeing of the structure so obtained. In this instance the desired pile configuration is developed in a subsequent step which may involve napping or other treating procedures. In this Way distortion and nonuniformities caused by the dyeing procedure are alleviated. In the case of nonwoven fabrics, however, it is frequently desirable, if not essential, to produce the final pile configuration before dyeing of the pile fibers. Particular care must therefore be observed to ensure that the subsequent dyeing step does not seriously impair the pile configuration since it may be quite difficult or expensive to later treat the fabric and suitably restore the pile configuration.

Although the so-called beam dyeing machines utilizing a perforated beam would seem well suited for the dyeing of such bulky nonwoven pile fabrics, experience has shown that in many cases it is exceedingly difiicult to form a satisfactory roll of fabric about the beam. As dye liquor flows outwardly through the perforations of the rotating beam and into contact with the accumulated windings thereon, there is a tendency for the windings to shift and slide under the weight of the dye liquor. As a consequence the product may undergo changes in dimensions and suffer from a nonuniform level of dyeing or still other undesirable characteristics.

For the beam dyeing of denser nonpile fabrics, the problem of initially obtaining a suitable roll on the beam can normally be alleviated by simply wrapping the fabric under tension. In the case of bulky nonwoven pile fabrics, these frequently having thicknesses of up to 0.5 inch or more, the amount of wrapping tension required to prevent slippage and sliding within the roll can be so excessive as to deleteriously affect the structure of the fabric. Even apart from the quality problem encountered in the beam dyeing of bulky nonwoven pile fabrics, there is still another serious problem; namely, one of economics in that the high bulk of such fabrics considerably restricts the quantity of fabric which can be treated during a cycle on a given piece of equipment.

It is therefore an object of the present invention to provide a process whereby fabrics, particularly bulky, nonwoven pile fabrics, can be dyed to avoid appreciable distortion of the fabric during dyeing. Another object is to provide a process whereby such fabrics can be beam dyed so as to realize substantial gains both with respect to properties of the product and the economies of the operation. Other objects will be apparent from the description of the invention which follows.

In the beam dyeing of fabrics it has been known to initially wind 21 length of fabrics about a foraminous or perforate "beam to form a wound roll of the fabric, and to thereafter cause the roll to be at least partially submerged in a bath of dye liquor. The fabric roll is then treated by rotating it in the bath and simultaneously cycling liquor from the bath into the beam and outwardly through the perforations thereof and into contact with the windings of the roll. The improved method of the present invention relates primarily to the manner in which the fabric is initially wound about the beam since, particularly in the case of nonwoven pile fabrics, this has "been found to markedly affect the properties and uniformity of the resulting product. in particular, the improved winding is accomplished by subjecting the fabric to compression as it is wound about the beam, the compression being effected in a direction normal to the plane of the fabric and applied across the width of the moving fabric as it tangentially contacts the outermost windings collected upon the beam. The apparatus by which the foregoing method is preferably accomplished utilizes a pressure roll mounted upon frame means for movement of the roll to and from a position in rolling contact with the fabric as it winds about the beam.

Although the invention will be particularly described with reference to the use of a dyeing liquor as the treating fluid, it will be understood that it can also be practiced utilizing other treating fluids such as scouring agents, bleaching agents and the like.

The invention will be further described with reference to the accompanying drawings, in which:

FIGURE 1 illustrates a side elevational view of a suitable dyeing apparatus, and

FIGURE 2 illustrates a front elevational view of the same apparatus, but with the top half of the dyeing vessel enclosure removed to show details of construction.

As shown in the drawings, a perforated beam 1 is mounted on bearings 2 and 3 which in turn are supported on the lower half of dyeing vessel 4 defined by bottom, side and end wall portions. The beam is driven at one end by sprocket 5, the other end of the beam being equipped with a rotating joint 6 which has pipe connections with the outiet of pump 7. The pump is in turn connected to the dye vessel at a point Well below liquid level 8. The beam is equipped with annular end flanges 9 which are spaced to slightly exceed the width of the fabric to be dyed. The flanges prevent telescoping of the fabric on the beam. The beam is perforated with closely spaced holes 1t which extend through the tubular wall portion thereof. The perforations 1%} are disposed circumferentially about a centrally located portion along the beam. The areas adjacent to each flange are imperforate to prevent liquor from channeling along the flanges 9. In a typical apparatus having an 88 inch spacing between the flanges for accommodating a fabric of nearly the same width, the imperforate or blind zone adjacent each flange is 12 inches in width. The position of flanges 9 along the beam may be adjusted so that the distance therebetween corresponds to the fabric Width. In operation they may be securely held in a given position by locking screws or similar means, not shown.

During loading, fabric 11 is guided to the apparatus from a conventional open-Width spreader and tensioning device, not shown. The fabric enters the apparatus through a loading door or other opening, not shown, in the front side wall portion of vessel 4, and is guided by bar 12 into the nip 13 formed between pressure roll 14 and the outermost surface 15 of windings accumulating on rotating beam 1. Pressure roll 14, which may be, for example, a solid stainless steel or other heavy hardsurfaced roll, is mounted by frame 16 such that its axis of rotation is substantially parallel with that of beam 1.

0 attached by connector 17 to the rear side wall portion of vessel 4 so that the pressure roll 14 may be swung to and from a position in rolling contact with the fabric as it winds about the beam. Guide bar 12, which may be either stationary or provided with means, not shown, for rotation, is mounted by an extension of frame 16 to be in substantially parallel alignment with the axis of pressure roll 14. Four small bearings Frame 16 is pivotally 18 at each end of pressure roll 14 permit rotation of the roll about its axis, i.e., so that the roll is free to move in contact with the moving fabric and at essentially the same speed. Guide bar 12 is positioned to lead the fabric 11 directly into the nip 13 so that it contacts tangentially the outermost layer of windings .15.

Pressure roll 14 is of sutficient width to traverse at least the centrally located perforate portion of beam 1. It should also extend across substantially the entire width of the fabric 11, ending just short of the inside walls of fianges 9.

Because roll 14 is situated above beam 1 and the accumulating windings thereon, the gravitational force cre ated by its weight in conjunction with that of associated parts such as the frame 16 is sufiicient to compress the fabric in a direction normal to the plane of the fabric 11 immediately as the latter contacts layer 15. A substantially constant compressive force is thus exerted from the start to the finish of the winding operation. The force of gravity employed to so compress the fabric may, if desired, be augmented or replaced by mechanical pressing devices. When a suitable size roll of fabric has been accumulated upon the beam 1, frame 16 is lifted upwardly so that roll 14 no longer contacts the fabric. The means for so lifting frame 16 comprises simply a cable '19, shown partially cut away, amxed to a centrally located uppermost portion of guide bar 12. By having the cable lead over a pair of pulleys and by manually applying counterweights to the opposite end, the frame 16 can easily be caused to swing upwardly and disengage the outer fabric layer 15.

The operation of the above-described apparatus will now be given in detail. With the dyeing vessel 4 empty of fluid but with the perforate beam 1 in rotatably mounted position therein, a few layers of an openly constructed fabric such as cheesecloth are first wrapped about the beam. This serves as a cushion to prevent the beam perforations from marking the pile fabric to be subsequently wrapped thereon and dyed. The fabric to be dyed is then led into contact with the outermost cushion layer upon the beam and a few wraps made by rotating the beam 1. The edges of the fabric should, of course, extend a few inches beyond the perforate portion of the beam and abut the inner walls of flanges 9. If the pile fabric includes a single pile layer attached to backing material, it may be wrapped so that the backing material is either on the inside, i.e. closest to the beam axis, or on the outside. Compression applied to the fabric to reduce the pile thickness during winding will generate recovery forces which give rise to the formation of a tightly maintained roll. If the pile fabric comprises a sandwich of two pile layers with the backing layer disposed there between, e.g., a double-faced structure of the type used for blankets, recovery forces will be generated by both pile layers.

The compression winding about the beam is then com menced by lowering the frame 16 so that pressure roll 14 rests in a supported position on the outermost layer of windings accumulated on beam 1. Guide bar 12 acts to guide the pile fabric directly into the nip 13 so that the weight of the roll is applied across the pile fabric width at the instant the fabric comes into contact with the outermost winding of pile fabric on the beam. A modest tension upon the pile fabric applied by some means upstream such as an unwind device, assists in keeping the pile fabric spread apart and in maintaining the proper entrance angle to the nip. Also, of course, the

tension serves to prevent slippage of the fabric under the pressure roll. The compression exerted upon the pile fabric as it passes under the pressure roll 14 considerably reduces the thickness of the pile layer. Upon release of the compression, however, the full thickness of the pile layer is not recovered owing to the cylindrical shape of the roll being formed. As a consequence of the continuing influence of the compressional forces as successive layers are accumulated, there is created a roll wherein each of the individual layers is restrained from recovering its normal thickness dimension. The recovery forces thus existing within the roll act to take up slack and prevent distortions in the shape of the roll once it is partially submerged in dyeing liquor. The compressional force applied by the pressure roll can vary widely depending upon such factors as the bulk, width and thickness of the fabric. Preferably the winding is effected such that the pile layer of the fabric has been compressed to a thickness which is less than 70% of its initial thickness. With certain bulky nonwoven pile fabrics, the compressed thickness may be less than 40% of its original value.

After a suitable size roll has been formed on the beam 1, rotation of the beam is stopped and frame 16 is lifted so that pressure roll :14 disengages the fabric 11. The free end of pile fabric is then secured against the roll first by a few outer wraps of cheesecloth or other material and then by tying the roll with cord. Dyeing liquor is then charged into vessel 4, preferably to about liquid level 8 so that the roll is only partially submerged in the liquor. The dye liquor is then pumped from the vessel into the beam so that it discharges radially outwardly from the perforations thereof and into contact with the pile fabric in the roll. In a typical operation, a fabric roll as large as 7 feet in diameter formed about a 30 inch diameter beam can be accommodated with flow rates of the dye liquor of the order of 1500 gallons per minute pumped through the perforated beam.

After the fabric has been dyed, a number of alternatives are available, either with fabric still on the beam or after removal from the beam. The fabric may be rinsed, then removed from the beam by reverse rotation, and then dried. If desired, the fabric may be steamed and then dried. However, steam may be used to recover the pile of the fabric in a separate operation followed by drying, or the steam may be used both for recovering the pile height of the fabric as well as for drying it. Optionally, the fabric, before or after drying, may be scoured, washed, treated with caustic solution, a fabric finish applied, the fabric may be stripped of dye, or it may be desized or bleached.

It will be understood that numerous modifications can be made of the above-described apparatus and process. If desired, for example, the dyeing vessel may be provided as a pressure tight vessel so that the dyeing can be effected under superatmospheric pressures.

A particularly suitable fibrous material for processing in the present invention is the porous, flexible, fibrous sheet material, with or without a backing, described and claimed by Koller in US. Patent No. 3,085,922. This sheet material is composed essentially of substantially parallelized crimped synthetic filamentary pile members, the pile members being attached at a plurality of contact points (preferably by a binder composition) throughout the three dimensions of the sheet, the faces of the sheet being composed essentially of fiber ends. When the bonded sheets and bonded or unbonded pile fabrics of the Koller patent are dyed by the method and apparatus of the present invention, the pile layer receives a compression, only a minor portion of which is automatically recovered when the dyed fabric is unwound. Subsequent to unwinding such a sheet material or fabric from the beam, the material may be steamed or otherwise heat treated in open-width at a temperature higher than the dye temperature in order to recover the pile height.

In dyeing certain types of bulky nonwoven pile fabrics in conventional beam dyeing machines, it has been discovered that a beam loaded with fabric does not hold its shape but becomes distorted, such as in the form of an egg, due to the heavy weight of dye liquor and fabric. By dyeing such fabrics in accordance with the invention while the fabric is securely held under compression, these problems are minimized and the fabric roll retains its shape stability. Distortion and wrinkling of the fabric surface is thus minimized with the result that improved dye uniformity is obtained. The apparatus and process of the invention avoids still another problem often encountered in the beck dyeing of bulky fabrics; namely, the tendency of the fabric to float on the dye liquor, thereby greatly reducing the machine capacity.

Another advantage of the present invention is that it can be operated with a favorable bath ratio so as to reduce the cost and loss of expensive dye liquor. The present invention has all the advantages of beam dyeing in addition to improved economies resulting from the use of compression to increase the fabric capacity.

The present invention may be used for the dyeing or other fluid treatment of woven, knitted, tufted and other forms of fabrics, foams, felts, warps, and the like. However, the invention is uniquely suitable for the dyeing of nonwoven fabrics, particularly those which are of a bulky nature and have a pile surface, such as the products described and claimed in the above-mentioned Koller patent. The invention is useful for dyeing a wide variety of apparel and industrial textile materials such as blankets, carpets, interlinings, fibrous sheets, batts, and the like, made from natural or synthetic fibers or filaments, or from blends of two or more fibers, including mixtures of natural and synthetic fibers.

The following example illustrates a preferred embodiment for carrying out the invention, but it is to be understood that the invention is not to be construed as being limited thereto.

EXAMPLE A nonwoven double-faced blanket pile fabric is employed wherein the pile layers are prepared according to the general procedures described in aforementioned Koller U.S. Patent No. 3,085,922.

Preparation of the pile fabric is as follows: crimped staple fibers of polyethylene terephthalate polymer consisting of a blend of 60 parts of 4 denier per filament, 2 inch long staple fibers having a three-dimensional curvilinear crimp and 40 parts of 1.5 denier per filament, 1.5 inch long staple fibers having a stuifer box type of crimp are carded to form a 160 grain/yard sliver. this sliver are assembled in side-by-side relationship to form a batt 40 inches wide x 96 inches long x 12 inches thick with the fibers generally aligned along the length of the batt. The batt is cut at 90 transverse to the direction of the fibers into sections 40 inches wide x inches long x 12 inches thick. A number of these sections are assembled with their 40 inch x 10 inch faces adjacent to one another and the assembly compressed to a density of about 0.9 lb./ft. within a perforated metal mold 40 inches wide x 48 inches long x 10 inches deep so that the fibers are generally directed towards the 40 inch x 48 inch faces of the mold. The mold is immersed into a 4% by weight binder solution in trichloroethylene solvent of a heat curable polyurethane formed of 2,4- toluene diisocyanate and polyester of ethylene glycol and adipic acid, then removed and excess binder solution allowed to drain. The assembly is heated at 240 F. for 1 hour to volatilize the solvent and cure the polyurethane resin. The bonded fiber assembly is removed from the mold and found to have a fiber density of 0.90 lb./ft. and a binder content of 7.6% based on the weight of the fiber. The bonded fiber assembly is sliced with a horizontal band knife to provide flexible, self-supporting bonded sheets & inch thick in which the faces of the sheets are composed essentially of fiber ends. One face Lengths of of each of two of these sheets is sprayed with an adhesive solution consisting of the following ingredients:

Grams Reaction product of a 1.6110 molar ratio of 2,4-

toluene diisocyanate and polytetramethylene ether glycol (M. W.=l000) Acetone 100 Particulate siiica (anhydrous colloidal) 10 The adhesive is applied at a level of 1.2 oz./yd. and to a depth of about 20% of the sheet thickness to give a discontinuous adhesive layer. The sprayed surfaces of the bonded fiber sheets are then placed against opposite faces of a 2.1 oz./yd. cotton muslin fabric and held together under 0.15 p.s.i. pressure while being heated at 240 F. for .7 hour in ethylene diamine vapor to cure the adhesive to produce a discontinuous vapor permeable adhesive layer that adheres the bonded fiber Wafers to the fabric. The double-faced pile fabric is then washed in a 4% caustic solution at F. for 15 minutes, rinsed and tumble dried. There is obtained a soft, flexible double-faced fabric suitable for use as a blanket; the resultant double-faced has good drape with a flexural rigidity value of 712 mg./cm.; a high air permeability, 268 ft. /rnin./ft. and a high thickness to weight ratio, .034 in./oz./yd. The pile layers have a high initial bulk, 69 cut /gram.

The doublefaced blanket fabric is dyed in the following manner: employing the arrangement illustrated in the drawings, a continuous length of 172 yards is loaded onto a perforated beam having a diameter of 31 inches as the beam is rotated continuously at a rate of 1.7 revolutions per minute. As the fabric contacts the outer winding on the beam tangentially during the loading, it is compressed with a stainless steel pressure roll weighing 240 pounds. The outside diameter of the pressure roll is 6 inches. The total dry weight of the blanket fabric is 208 pounds and the loading compression of the fabric is sufficient to reduce the pile thickness, on a calculated basis, by about 45%. After loading, the following dyeing procedure is followed:

(1) The vessel is filled with 1500 gallons of water while the fabric roll is rotated. The bath level reaches the inside diameter of the beam.

(2) The pump is started to circulate approximately 1500 gallons per minute, and an additional 200 gallons of water is added to maintain the original bath level. The bath temperature is raised to 100 F. by jetting steam into the water.

(3) Two hundred ninety-five grams of an anionic wetting agent which is the sodium salt of a long chain alcohol sulfate and 170 grams of an anionic Wetting agent which is the sodium salt of the sulfate of the condensation prodnet of ethylene oxide and oleyl alcohol are then added to the dye bath.

(4) After 10 minutes of circulating the bath through the fabric, the pH is adjusted to 8.0-9.0 by adding approximately 3000 grams of tetrasodium pyrophosphate.

(5) Then 22.7 grams of a red dyestulf is added to the bath. This dyestuff has a Color Index No. 29065 (second edition).

(6) The bath temperature is raised to F. at a rate of 1 per minute and the operation is continued for 20 minutes.

(7) Three hundred pounds of sodium chloride are then added to the dye bath over a 20 minute period.

(8) The bath is held at 180 F. for 20 minutes.

(9) One-half of the bath is drained from the vessel and this amount of liquid is replaced with clean water with the pump running and the beam rotating.

(10) The procedure of step 9 is repeated and then the dye bath is drained completely from the vessel.

The blanket fabric is unloaded from the beam by reverse rotation and the fabric is dried by passing through a tenter frame. Then the fabric is steamed on the open tenter frame and dried again on the frame. The resulting fabric is an attractive red blanket that shows level dyeing. The blanket is free of wrinkles and shows no visual surface distortion. A steaming treatment of the blanket on the tenter frame after dyeing causes the pile fibers to recover to 95% of the original total fabric thickness.

Even apart from the improved dye level and other properties of the resulting dyed product, it will be noted that approximately 45% by weight more fabric is processed than would be possible on a standard beam dyer of the same diameter loading beam, but without the use of compression winding.

What is claimed is:

1 In a method for treating a nonwoven pile fabric with a fluid comprising the steps of initially winding a length of a fabric about a forarninous beam to form a wound roll of said fabric, and thereafter causing the roll to be at least partially submerged in a bath of treating fluid and effecting fluid treatment of said roll by rotating said roll in said bath and simultaneously cycling fluid from the bath into said beam and outwardly through the perforations thereof and into contact with the windings of said roll; the improvement wherein the intial winding about said beam is etfected under compression as the beam is rotated to considerably reduce the thickness of said nonwoven pile fabric, the compression being effected in a direction normal to the plane of the fabric and applied across the width of the moving fabric as it tangentially contacts the outermost windings upon said beam.

2. The method of claim 1 wherein said fluid is a dyeing liquor.

3. The method of claim 1 wherein the thickness of said fabric is reduced to less than about 70% of its original thickness by said compression.

4. The method of claim 1 wherein said nonwoven pile fabric comprises a sheet material composed essentially of substantially parallelized crimped synthetic filamentary pile members, the pile members being attached at a plurality of contact points throughout the three dimensions of said sheet material, the faces of the sheet material being composed essentially of fiber ends.

References Cited by the Examiner UNITED STATES PATENTS 1,266,110 5/1918 Dudley 6815O FOREIGN PATENTS 406,450 11/1924 Germany.

IRVING BUNEVICH, Primary Examiner.

Claims (1)

1. IN A METHOD FOR TREATING A NONWOVEN PILE FABRIC WITH A FLUID COMPRISING THE STEPS OF INITIALLY WINDING A LENGTH OF A FABRIC ABOUT A FORAMINOUS BEAM TO FORM A WOUND ROLL OF SAID FABRIC, AND THEREAFTER CAUSING THE ROLL TO BE AT LEAST PARTIALLY SUBMERGED IN A BATH OF TREATING FLUID AND EFFECTING FLUID TREATMENT OF SAID ROLL BY ROTATING SAID ROLL IN SAID BATH AND SIMULTANEOUSLY CYCLING FLUID FROM THE BATH INTO SAID BEAM AND OUTWARDLY THROUGH THE PERFORATIONS THEREOF AND INTO CONTACT WITH THE WINDING OF SAID ROLL; THE IMPROVEMENT WHEREIN THE INITIAL WINDING ABOUT SAID BEAM IS EFFECTED UNDER COMPRESSION AS THE BEAM IS ROTATED TO CONSIDERABLY REDUCE THE THICKNESS OF SAID NONWOVEN PILE FABRIC, THE COMPRESSION BEING EFFECTED

Images