US2655711A - Shrinkproofing of fabrics - Google Patents

Description

Oct. 20, 1953 c. G. HATAY SHRINKPROOFING OF FABRICS 3 Sheets-Sheet 1 Filed Jan. 5, 1950 INVENTOR. Claw/P4 .55 6 H4 74% Oct. 20, 1953 c. G. HATAY SHRINKPROOFING OF FABRICS 3 Sheets-Sheet 2 Filed Jan. 5 1950 oaocreaooicao I ZNVENTOR. wa s 6. ///2 my Oct. 20, 1953 c. G. HATAY SHRINKPROOFING OF FABRICS I5 Sheets-Sheet 3 Filed Jan. 5, 1950 IN VEN TOR. (WA/GA [a 5 #4 m 1/ BY SW mg Patented Oct. 20, 1953 SHRINKPROOFING OF FABRICS Charles G. Hatay, Georgetown, Mara, assignor to E-Z Mills, Inc, New York, N. Y., a corporation of New York Application January 5, 1950, Serial No. 136,958

20 Claims. 1

This invention relates to the treatment of textile fabrics, and particularly to an improved process for shrink-proofing such fabrics.

Heretofore, various methods hav been devised for shrink-proofing fabrics, that is, for making them substantially non-shrinkable in at least one direction. These methods generally comprise stretching the fabric under heavy tension in the direction of one set of its constituent yarns, such as the wefts, while leaving the fabric free "to contract in the direction of the other set of its constituent yarns, such as the warp yarns. Before or during the application of the heavy tension to the fabric, it is moistened or steamed, and after the tensioning treatment it is dried or ironed, or both, to set the yarns. As a result, the weft yarns of the fabric are substantially straight, while the warp yarns are provided with a pronounced crinkle, whereby the fabric is quite resistant to shrinking in the warpwise direction when it is subsequently laundered. In some cases, the process is supplemented by steps involving the application of moisture, heat and pressure, to reduce the shrinkage in the weftwise direction when the fabric is laundered.

Some of these prior methods have enjoyed considerable commercial success in the treatment of woven fabrics. However, the prior methods have been found to be unsatisfactory for knitted fabrics, evidently because the stresses introduced into knitted fabrics by the knitting and other opera tions incident to their manufacture are of different character than those present in Woven fabrics. Consequently, there has been no commercially acceptable process for shrink-proofing knitted fabrics, although there is a great demand for such a process.

One object of the present invention, therefore, is to provide a shrink-proofing process which is applicable especially to knitted fabrics.

Another object is to provide an improved shrink-proofing .process which does not require heavy tensioning of the fabric, as is common in the prior processes.

A further object is to provide an improved process for treating textue fabrics, whereby in a few simple operations the fabric is made extremely resistant to shrinking, without impairing the quality of the fabric, and, in fact, with a further improvement in its quality.

The process of the invention comprises essentially the following steps: 1') The fabric, while completely wetted, is placed in a substantially te'n-s'ionless and compressionless condition to cause displacement of the fabric fibres by the internal stresses therein, so that these stresses are relieved or eliminated with the rearrangement :of the fibres. In this first or ale-stressing operation, the fabric is preferably spread under the surface of a water bath so that th weight of the fabric is compensated by its buoyancy, and the friction of the water is applied to the fabric on a surface which is many times greater than the acting surfaces of the rollers of a. conventional spreader. (2) An alternating electric current is passed through the fabric, while thus de-stressed and retaining at least some of the wetting agent, to cause internal heating of the fabric -di-electrically until it is substantially freed of the wetting agent by evaporation.

I have found that the combination of these two steps is highly effective for shrink-proofing fabrics, the shrinkageof a test length of knitted cotton fabric, treated by my process, being considerably less than 1% in a subsequent laundering. I believe that the steps of my process operate to shrink-proof the fabric by an action substantially as follows: In the .first or de-stressing operation, the water film covering every fibre of the fabric acts as a lubricant to diminish inter-fibre friction and also penetrates the fibres themselves, causing an increase in the diameter of each fibre and tending to shorten it. Thus, when the completely wetted fabric is placed in a near tensionless and compressionless condition, that is, relieved of external stresses, the small forces inside each fibre are released and act to displace the fibre to a position or form wherein these internal forces are substantially eliminated. The subsequent passage of the alternating electric current through the fabric, while the fibres are thus displaced and therefore still de-stressed internally, not only evaporates water in the fabric by internal heating thereof di-electrically, but also acts in some manner to "set or stabilize the fibres in their de-stress'ed condition.

For best results in shrink-proofing fabrics according to theinvention, the mechanical handling of the de-stressed fabric, prior to completion of the stabilizing or "setting operation, should be carefully controlled to avoid heavy external stresses on the fabric. The application of heavy tension to the fabric during this period tends to reduc the shrink-proofing effect, evidently because it distorts the fibres from their relaxed positions or forms which they assume in the destressing operation and thereby creates interfibre and intra-fibre stresses which remain in the fabric upon completion of the stabilizing or setting operation.

In the preferred practice of the invention, the fabric is subjected to the de-stressing operation by passing a length of it continuously through a body of the wetting agent where it is spread while submerged, so that it is supported in a relaxed condition by its own buoyancy. It is then subjected to the stabilizing or setting operation, either by passing it continuously between the electrodes of a high-frequency dielectric heater or by coiling it on a mandrel which is subsequently utilized as an electrode for passing the alternating electric current through the fabric coil. The mandrel may be made hollow to serve also as a duct for passing an air current through the fabric coil, to remove moisture evaporated by the dielectric heating. The alternating current is first passed through the fabric coil at low frequency, but as the evaporation proceeds and the electrical resistance of the fabric increases, the frequency is increased so that at the end of the operation a high frequency current is passing through the coil. Thus, the fabric is at relatively low temperature except at the final period of the operation. when it reaches a temperature above the boiling point of water. The air current for removing the evaporated moisture is preheated by the heat given off while generating the high frequency current, and also by the moist air current exhausted from the fabric coil.

For a better understanding of the invention, reference may be had to the accompanying drawings, in which,

Fig. 1. is a schematic View of a preferred installation for use in practicing the process;

Fig. 2 is a longitudinal sectional view of the fibre de-stressing apparatus of the installation taken along line 2--2 of Fig. 3;

Fig. 3 is a plan view of the apparatus illustrated in Fig. 2;

Fig. 4 is a sectional view on the line 4-4 in Fig. 2, and

Fig. 5 is a schematic view, partly in vertical section, of the fibre stabilizing or setting apparatus of the installation.

For illustrative purposes, the invention will now be described, by reference to the drawings, in connection with the treatment of knitted cotton fabrics, although it will be understood that the invention may also be used for the treatment of other fabrics.

Referring to Fig. 1, the numeral I0 designates a conventional dye booth or bleaching and washing booth which receives the fabric. in the form of an elongated tube. From the booth ID, the fabric tube is delivered to the tank II of the destressing apparatus I2, which is illustrated in Figs. 2, 3 and 4 and will be described in greater detail presently. The tank II communicates with one end of a trough I2a which is filled with a wetting agent, such as water, to the level A. The fabric tube is drawn continuously from the tank II and moved slowly along the trough I2a under the surface of the water bath. During its longitudinal movement along the trough, the fabric tube is spread under the surface of the bath and placed in a substantially tensionless and compressionless condition, whereby the fabric is relieved of external stresses while completely wetted. After the internal stresses in the fabric fibres have been relieved or eliminated as a result of this treatment, the fabric is wound in a coil I3 on a, hollow perforated mandrel I4 of electrically conductive material, the winding being effected in such a manner as to avoid heavy external stresses on the fabno.

When the fabric tubing has been completely wound on the mandrel, the coil I3 is removed from the de-stressing apparatus I2 and, after application of a perforated conducting layer I5 around the outside of the coil, placed in a centrifuge I6. The latter is provided with upper and lower bearings I 6a and I 6b, respectively, which receive removable studs I4a projecting from the ends of the mandrel. By means of a motor I60, the mandrel I4 is rotated at high speed on a vertical axis in the centrifuge, so as to extract a substantial part of the water centrifugally from the fabric coil, the water being discharged from the centrifuge in any suitable manner. During the centrifuging of the fabric, the coil is confined by the conductive layer I5 surrounding it.

The fabric coil, thus partially dried, is then transferred to the fibre stabilizing or setting" apparatus I8, which will be described in greater detail in connection with Fig. 5. The apparatus I8 comprises a housing l9 which encloses an oscillator I9a for generating both L. F. and H. F. electric currents, and comprises also a container 20 which receives the fabric coil after removal of the studs Ida from the mandrel. At its lower end, the mandrel I4 is seated on the bottom of the container 20 around an opening which communicates with a vapor discharge device 2| below the container, the upper end of the mandrel being closed. The oscillator I9a has one terminal 1% connected to the conductive layer I5 on the fabric coil, and a second terminal I connected to the mandrel I4, whereby the mandrel and the layer I5 serve as electrodes. An alternating electric current generated by the oscillator I9a is passed through the fabric coil from the outside to the mandrel electrode I4, the current being at low frequency at the outset. Accordingly, the fabric coil is internally heated di-electrically by the passage of the alternating current through it, thereby evaporating water in the fabric. As the evaporation proceeds, the resistance of the fabric increases,

and subsequently the oscillator [9a is adjusted to pass an H. F. current through the fabric. The di-electric heating is continued until the temperature in the fabric becomes above the boiling point, at which time the fabric is completely freed of the water. During the di-electric heating, an air current is forced into and. through the oscillator housing I9 by a pump I9d, so as to preheat the air by the heat losses from the oscillator incident to generating the alternating current. From the housing I 9, the air current is passed through a pipe I9e into the container 20, where it passes from outside the fabric coil through the fabric, the perforations in the mandrel I4, and thence through the lower end of the mandrel into the vapor exhausting device 2|, from which the condensate is discharged at 2Ia and the air current is exhausted through pipe 22. In this way, the heated air current supplements the di-electric heating action and serves to heat-insulate the fabric coil and also to remove the evaporated moisture from the coil so as to prevent recondensation.

The de-stressing apparatus I2, as shown in Figs. 2, 3 and 4, comprises a trough I 2a which at one end opens into upper part of the tank II. The opposite end of the trough is closed, as shown at I217. The tank II and the trough [2a are filled with a wetting agent, such as water, to the level A (Figs. 2 and 4) the tank. I I being provided with a level outlet 24. In the tank II, where the fabric F is placed in a, random-twisted. condition from thebooth HI (Fig. l) or other suitable stage in the normal processing. of the fabric, the. fabric F is in a completely wetted state and. tends float under the surface A of the. waterbath. One end of the fabric tubepasses over a horizontal; pipe 25 having holes 2.5a spaced along the pip between flanges or guides. 2517 The pipe 25 is supported on an oscillating arm or pendulum. 25: which is hollow and is connected to a source of compressed air (not. shown) whereby air is blown. continuously through. the holes 2511 in the upper surface of the pipe 25. In this way, the. fabric: tube is inflated, as shown at F", by the air'from the oscillating pipe 25, the air being more or less confined between the pipe 25 and a pair of rollers: 27 mounted in the opening between trough l2o and tank ll. Thus, the inflated part F of the fabric tube will float on the surface A of thebath, and this floating action, in combination with the oscillations of the pipe 2.5, serves to untangle. the fabric tube as it is drawn. out of the tank II'.

From the rollers. 27, the fabric passes, to a spreader which comprises a horizontal plate 28. extending across the trough l'2a. fromone side to the other. The plate 28 is disposed below the surface A of the bath but above the bottom of the trough [2a, and it is slightly bowed downward so that the lower face of the plate is con-- vex. The plate 28 is made of a water repellent, highly polished material, preferably a transparent plastic material, and is provided along its sides with openings 28a. A compressed air pipe 29- has a horizontal section 29d extending longitudinally of the trough under the central portion of the curved plate 28', the horizontal pipe section 29a being provided. with holes 2% spaced along the length of the pipe. The fabric Fpasses, below the plate 2.8,, so that air bubbles from the pipe 290.. rise to the fabric at the central or. lowermost portion of the plate and thus urges the fabric against the lower surface of the plate. Since the plate 28 is imper-forate except at its sides, the air bubbles from the pipe 29o spread outwardly and upwardly under the plate into the fabric on both sides of the central portion, the bubbles finally escaping. through the side openings 2811. In this way, the bubbles act to spread the fabric against. the lower face. of the. plate 28, the highly polished surface of which serves, to reduce the friction tending to oppose the spreading of the fabric by the bubble action.

The fabric from. the spreader 28----29 passes under a roller 31, over a roller 32, and then under a roller 33, these rollers being transport. rollers extending transversely between the sides of the trough and below the surface A. of the bath. The intermediate roller 32 is driven by a belt 34 from a squirrel-cage electric motor 35.

The belt 34 is arranged to provide a continuous slippage between the belt and the driving motor 35; but as the fabric is pulled along the trough l2a (by a mechanism to be described presently) the transport roller 32 effects an additional pull on the fabric, the force of this pull being substantially constant due to the slippage between the belt 34 and the motor 35.

The fabric F passes from the transport rollers 3|, 32, 33 to a second spreader comprising a plate 35 and an underlying perforated air pipe 31a, which are similar to the parts 28 and 29a, respectively of the first air spreader.

From the second air spreader 36, 31a, the fabric passes between a pair of rollers 33 to a shaker device comprising a pair of rollers 40 and, 411d mounted on. a carriage 4i suspended on one end of a flexible am 42,. the. other end of the. arm.

being mounted on a support. 43. The arm 42- rests upon an eccentric 44 which is rotated by" a suitable power source (not shown). As the fabric passes between the rollers and 40a, it is subjected to a gentle shaking action below the. surface of the bath by the vertical reciprocation imparted to the rollers through the eccentric 44'. This oscillatory movement of the fabric, against the; friction of the. water, facilitates re.- lease of the internal stresses in the fabric fibres.

An endless belt 45 is. disp sed in the trough In in front of the shaker device and receives the fabric after the shaking action. The belt 45 is mounted on a. series of rollers 46, 46a, 46b, 46c and 8d. The fabric. from the. shaker device moves upon the endless belt 45 between the latter and an idler roll 41. The endless belt is driven from a. suitable power source (not shown) by a drive belt 48 extending around a pulley 49' on one end. of the; roller 46'.

At opposite sides of the. tank [2a are vertical supports 5| having vertical slots 5la which receive the removable studs 14a. on the hollow perforated mandrel M. The fabric from the endless belt 45 is wound around the mandrel l4 to form the. coil l3. The mandrel I4 is not driven, but the coil I3 is caused to turn by friction on the endless belt 45, the coil being supported by the underlying rollers 45c and 46d over which the endless belt extends. As the diameter of the coil increases, due to winding of additional fabric on the coil, the studs 14a. of the mandrel slide upwardly in the slots 51a of the supports 5|. A squeeze roller 52, which is provided with a semi-rigid rubber surface, has studs 52a disposed in the. slots 51a and rests upon the upper surfaceof the fabric coil l3. The squeeze roll 52 rides upwardly in the guide. slots 5la as the mandrel l4 rises from the belt 45 and the underlying rollers 46c and 46d, due to enlargement of coil I3 as the winding proceeds. In the embodiment shown the weight of the roller 52 is utilized to maintain proper pressure of this roller against the fabric wound upon the fabric coil I3 and the studs or trunnions 52a are carried in open guide slots cm, which permit the lifting of the roller for releasing pressure. The invention, however, is not concerned with the details of the arrangement with respect to the specific mounting of the roller or manner of obtaining the desired pressure of the roller against the fabric coil [3.

'In the operation of'the (lo-stressing apparatus l2, the fabric tube is moved slowly along the trough 12a due to the pull imparted to the fabric as it passes between the endless belt 45 and the fabric coil 13. Since the mandrel I4 is not positively driven, the apparatus avoids any heavy tension on the fabric. as it is drawn through the water bath. The. pulling of the fabric by the endless belt 45, acting on the bottom of the coil [3, is supplemented by the transport rolls 3!, 32, 33, it being understood that similar transport rolls may be located in other parts of the trough I20, so as to provide a uniform movement of the fabric along the trough under near tensionless conditions. By air-spreading the fabric between the curved plates 28-36 and the compressed air 1 pipes 28a31a, the fabric is supported in a flattened condition under the surface of the bath by the buoyancy of the fabric in the liquid, whereby the fabric is placed under a substantially com pressionless and tcnsionless condition wh le com:

pletely wetted. Because of the absence of heavy compression rollers or heavy tensioning of the fabric while it is moved through the bath and then wound on the mandrel I4, the fabric fibres remain in the relaxed positions to which they were displaced by the treatment in the trough I2a, whereby the fabric coil I3 is substantially destressed.

The trough IZa is provided at the sides with adjustable arms 54 which carry depending guides 54a engageable with the side edges of the fabric tube F as it moves along the trough. Similar adjustable guides (not shown) may be arranged at other parts of the trough to guide the fabric in its movement.

Referring now to Fig. 5, the fabric coil I3 with its mandrel I4 is transferred to the container 20 after partial drying of the fabric in the centrifuge I6 (Fig. 1). The container 20 has a removable cover 200. and is provided at the bottom with a central ring 56 which receives and locates the lower end of mandrel I4. The bottom of container 20, where it is surrounded by the ring 56, has openings 5'! which lead into the vapor discharge device ZI. The perforated conducting layer I5 is retained on the fabric coil when it is placed in the container 20.

The high frequency oscillator Isa may be of any conventional design, and since such oscil1a tors are well known, it is not necessary to describe it in detail. The anode 58a of the oscillating tube 58 is provided with a heat exchanger 59 Which receives a current of air sucked into the housing I9 through an inlet 60, whereby the air current is preheated by the heat losses from the anode 53a. Additional air is drawn into the housing I9 from an inlet 6| to the power regulator 62, containing the usual rectifier tubes (not shown), from which the air preheated by the heat losses in the regulator 62 passes through a passage 63 into the housing I9. Similar cold air inlets may be provided at the oscillating tank coil (not shown) and other points where heat is dissipated incident to generating the high frequency current, so that the greatest part of the heat losses are used to preheat air passing into the housing IS. The air thus preheated is drawn through an outlet 64 and a pipe 65 to a compressor 66, a check valve 61 being located in the pipe line between the compressor and the oscillator housing IS. The compressor 66 forces the preheated air into a high pressure container 68 containing a cooling coil 68a, which serves to condense a considerable part of the moisture content of the air entering the oscillator housing I9 from the atmosphere.

From the compressed air container 68, the air passes through an oil filter I and a pipe line H to a heat exchanger I2 located in the discharge device 2| below the openings 51. The pipe II extends from the heat exchanger I2 to a second heat exchanger I3 containing a coil 14 through which steam is circulated under pressure to heat the air to a temperature between 230-270 F. From the heat exchanger 13, the compressed air passes through distributing pipes 15 into the container 20 for the fabric coil.

The steam from the heating coil 14 passes through a pipe 16, which is provided with a pressure regulating valve 16a, to a jet-suction ejector Tl located in a discharge nozzle 2Ib projecting from the bottom of the discharge device 2|. Accordingly, the preheated air from pipes I reaches the interior of container 23 at high pressure and expands in the container so that it is capable of taking up a substantial amount of moisture from the fabric, and the pressure differential is accentuated by the ejector 11 to cause a further expansion of the air-stream mixture in container 20 and thereby allow a higher degree of saturation. From the pipes I5, the expanding air passes through the perforated conducting layer I5 and then radially inward through the fabric coil I3 and through the perforations Hb in the mandrel to the interior of the latter, the upper end of the mandrel being closed by a plug 18. The hot and wet air is discharged from the mandrel I4 through the openings 51 into the discharge device 2I, where the air passes around the heat exchanger 12 so as to preheat further the air passing through pipe II to the distributing pipes 15. From the ejector H the steam and wet air is exhausted through the pipe 22, and the condensation is discharged through the bottom outlet Zla.

The high frequency oscillator ISa. has terminals and 80a engageable by switch arms 8| and 8 la connected to the conductors I 9b and I 90, respectively. These conductors extend through insulated openings 20b in the container wall and into the interior of the container 20, where the conductor I9c is connected to a conducting ring 82 surrounding the lower part of mandrel II. The other conductor I9b is connected through a flexible conductor 83 to the perforated conductive layer I5 extending around the outside of the fabric coil.

At the beginning of the stabilizing or "setting" operation, when the fabric coil I3 is still very wet, the switch arms BI and Bla are connected to the terminals 84 and 8411, respectively, of a low frequency oscillator 8585a, which may be of any conventional design. The L. F. oscillator 85-85a provides an alternating current of sufficient voltage to cause an electrical current to pass through the fabric coil I3 between the outside electrode I5 and the internal electrode or mandrel I 4. The resultant internal heating of the fabric di-electrically increases the temperature of the fabric and causes water therein to evaporate. The hot and dry air passing through the fabric, as indicated by the arrows in Fig. 5, supplements the di-electric heating effect and also becomes saturated with the evaporated moisture and carries this moisture into the interior of mandrel I4, the air-steam moisture then passing around the heat exchanger 12 where it loses most of its heat content to the colder air in pipe 1|. Most of the moisture in the discharging air will be condensed by the heat exchanger 12 and exhausted through the ejector 11.

After the moisture content of the fabric has been lowered by the L. F. di-electric heating, the electrical resistance of the fabric will increase to the point where no appreciable current will pass between the electrodes I5 and I4. At this time the switch arms BI and Ola are moved to disconnect the L. F. oscillator and connect the H. F. oscillator I8a to the fabric coil through the terminals 80 and 80a, respectively. This H. F. current acts to ionize the moisture remaining in the fabric, so that the electrical resistance of the fabric apparently decreases. The frequency of the current generated by the H. F. oscillator I9a is gradually increased as the cloth becomes drier due to the di-electric heating and the removal of the moisture by the heated air current. When the fabric coil I3 has been substantially freed of its moisture content, the switch arms 8I-8Ia are moved to disconnect the fabric 011 from the current source and the operation is terminated.

During the entire period when the L. F. and H. F. currents are passing through the fabric coil 13, the pre-heated air is passed through the fabric coil from the high pressure pipes 15 to the steam ejector 11, so that the air current acts as a heat insulator to prevent radiation from the surface of the cloth and also prevents recondensation of the evaporated moisture. Due to the di-electric heating of the fabric, the fabric temperature remains below 100 C. until near the end of the operation, when the temperature exceeds 100 C., and the heating is preferably continued until the fabric reaches a temperature of about 110C.

While I have described and illustrated a preferred installation for practicing the process, it will be understood that the fibre de-stressing and stabilizing or setting operations of the invention may be performed by installations of different design.

I claim:

1. A process for treating textile fabrics, which comprises floating the fabric, while completely wetted with a wetting agent, in a substantially tensionless and compressionless condition to cause displacement of the fabric fibres by the internal stresses therein, thereby relieving said stresses, maintaining the fabric substantially free of internal tension after said relieving of the internal stresses and until passage therethrough of the alternating current hereinafter specified, and passing an alternating electric current through the de-stressed fabric to cause internal heating of the fabric (ii-electrically until it is substantially freed of the wetting agent by evaporation.

2. A process according to claim 1, comprising also the step of passing an air current through the de-stressed fabric to remove the evaporated wetting agent.

3. A process according to claim 1, comprising also the step of enclosing the de-stressed fabric in a current of heated air during the passage of said current through the fabric.

4. A process according to claim 1, comprising also the step of changing the frequency of said alternating current from a low frequency to a high frequency as the evaporation proceeds.

5. A process according to claim 1, comprising also the step of mechanically extracting partof the wetting agent from the de-stressedfabric prior to passage of the alternating current through the fabric.

6. A process according to claim 1, in which the fabric is spread freely under the surface of a body of said wetting agent to place the fabric in said tensionless and compressionless condition.

7. A process according to claim 1, comprising also the step of winding the de-stressed fabric in a coil before passing said alternating current through the fabric, and in which said current is passed through the coil between the coil axis and the outside of the coil.

8. A process according to claim 1, comprising also the steps of winding the de-stressed fabric in a coil and spinning the coilon its axis to extract part of the wetting agent centrifugally from the fabric before passing the alternating current through the fabric, and in which said current is then passed through the coil between the coil axis and the outside of the coil.

9. A process according to claim 1, in which the passage of said alternating electric current through the de-stressed fabric i continued until the fabric reaches a temperature of about C. 10. A process according to claim 1, comprising also the step of subjecting the wettedfabric to a gentle shaking actionwhile it is in said tensionless and compressionless condition, to facilitate relieving of said internal stresses.

11. A process for treating textile fabrics, which comprises placing the fabric, while completely wetted with a wetting agent, in a substantially tensionless and compressionless condition to cause displacement of the fabric fibres by the internal stresses therein, thereby relieving said stresses, winding a length of the de-stressed fabric into a coil on an electrically conductive mandrel, and passing an alternating electric current through the coil of de-stressed fabric from outside the coil to the mandrel as an electrode, to cause internal heating of the coil (ii-electrically until it is substantially freed of the wetting agent byevaporation,

l2.,A process according to claim .11, comprising also the step of applying an electrically conductive layer to the outside of the coil, and in which said layer is used as a second electrode for passing the alternating current through the fabric coil.

13. A process according to claim 11, comprising also the step of spinning the fabric coil on said mandrel to extract part of the wetting agent centrifugally from the fabric before passing said alternating current through the coil.

14. A process for treating textile fabrics, which comprises placing the fabric, while completely wetted with a wetting agent, in a substantially tensionless and compressionless condition to cause displacement of the fabric fibres by the internal stresses therein, thereby relieving said stresses, winding 2. length of the de-stressed fabric into a coil on a hollow perforated mandrel of electrically conducting material, passing an alternating electric current through the coil of destressed fabric from outside of the coil to the mandrel as an electrode, to cause i nter nal heating of the coil di-electrically until'it is substantially freed of the wetting agent by evaporation, and passing an air current through the fabric coil between the interior of the mandrel and the outside of the coil to remove the evaporated wetting a ii 15. A process for treating textile fabrics, which comprises feeding a length of the fabric into a bath of a wetting agent, spreading the fabric below the surface of the bath and there supporting the fabric by its buoyancy in the bath to place the fabric in a substantially tensionless and compressionless condition while completely wetted and thereby cause displacement of the fabric fibres by the internal stresses therein, whereby said stresses are relieved, moving the fabric through the bath while so supported therein and then out of the bath, while maintaining the fabric substantially free of tension, and passing an alternating electric current through the destressed fabric immediately after it leaves the bath and as it is withdrawn from the bath, to cause internal heating of the fabric di-electrically until it is substantially freed of the wetting agent by evaporation.

16. A process according to claim 15, in which the fabric is spread below the surface of the bath by blowing air into the bath below the fabric.

17. A process according to claim 15, in which the fabric is spread below the surface of the bath by blowing air into the bath below the fabric, and

11 confining the upper surface of the fabric against the buoyancy imparted thereto by the air.

18. A process according to claim 15, comprising also the step of subjecting the fabric, while moving through the bath, to a gentle shaking action to facilitate relieving of said internal stresses.

19. A process according to claim 15, comprising also the steps of passing the fabric from the bath around a rotatable mandrel to form a coil, and winding the fabric on the mandrel by rotating the coil from the outside at a peripheral speed equal to the linear speed at which the fabric moves through the bath, to maintain the fabric substantially free of tension, said alternating electric current being passed through the fabric coil from the outside of the coil to said mandrel as an electrode.

20. In the treatment of textile fabrics, the process which comprises generating a high-frequency alternating electric current, passing said current through the fabric while in a wetted condition to cause internal heating of the fabric dielectrically, thereby evaporating moisture in the fabric, passing an air current through the generating locus of said current, to preheat the air by heat produced in said generating, and blowing the pre-heated air through the fabric to remove evaporated moisture therefrom.

CHARLES G. HATAY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 637,685 Vockler Nov. 21, 1899 1,646,498 Seede Oct. 25, 1927 2,344,557 Mann et al Mar. 21, 1944 2,365,931 Benger Dec. 26, 1944 2,403,800 Hoyler July 9, 1946 2,474,717 Belcher June 28, 1949 2,485,609 Koster et a1 Oct. 25, 1949

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