US3484179A - Method for selective heating in textiles with microwaves - Google Patents

Description

Dec. 16, 1969 R. s. ADAMS ETAL METHOD FOR SELECTIVE HEATING IN TEXTILES WITH MICROWAVES Filed Aug. i7, 1966 1" RECTIFIER OSC'LLATOD 2 Sheets-Sheet 1 susomoois WET MATERIAL v INVENTORS RICHARD G- ADAMS JOHN F. COBIANCHI ATTORNEY Dec. 16, 1969 R ADAMS ETAL 3,484,179

R SELECTIVE ATING IN TEXTILES WITH M Filed Aug. 17, 1966 2 Sheets-Sheet 2 INVENTORS RICHARD G.ADAMS JOHN F- COBIANCHI ALAN ROTH ATTORNEY United States Patent 3,484,179 METHOD FOR SELECTIVE HEATING IN TEXTILES WITH MICROWAVES Richard G. Adams, Upper Montclair, John F. Cohianchi, Saddle Brook, and Alan Roth, Passaic, N.J., assignors to J. P. Stevens & Co., Inc., New York, N.Y., a corporation of Delaware Filed Aug. 17, 1966, Ser. No. 573,018 Int. Cl. D06p 7/00 U.S. Cl. 8-2 18 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a process of selectively depositing a finishing agent on a fabric having directionally oriented yarns. In this process, a composition containing a liquid carrier having a high dipole moment and a finishing agent is applied to the fabric'and the resulting product is then dried by means of an oscillating high frequency electrical energy field which is substantially parallel to the plane of the fabric. The concentration of finishing agent deposited on the yarn in a given direction is controlled by selecting the direction of the electrical field.

The term high frequency electrical energy refers to frequencies above about 3,000kc., particularly in the range of about 20,000 to about 30,000 kc.

The term oriented substrates as used herein refers to substrates having a definite, non-uniform yarn or filament structure. For example, in woven articles the fabric substrate possesses a warp yarn and weft (fill) yarn orientation. However, the oriented substrates of this invention are not limited only to fabrics produced by conventional weaving procedures, but also include woventype substrates which, though produced by fabrication procedures other than weaving, possess a definite longitudinal or latitudinal orientation. Illustrative of other procedures which can be used to produce suitable nonuniform oriented substrates are knitting, punching and various miscellaneous procedures used to produce webs and scrims such as air and crosslaying.

Further, the yarns or filaments which are used to produce the oriented substrates can be of-natural or synthetic derivation or can be mixtures of these. For example, the substrate can be a cellulosic such as cotton, flax, jute, rayon or a substrate of proteinaccous origin such as wool, silk, hair and the like. Also useful as substrates are the synthetics such as the siliceous fiber, the polyamide, r

polyesters, polyolefins, acrylics and the like or their blends with other synthetics or natural fibers.

The substrates can be in the form of knitted fabrics, woven fabrics, garments and/ or assemblies. When siliceous substrates are used they can be Woven into the materials referred to in the art as fiber glass or glass wool, etc.

Finishing agents as used herein refer to that group of agents used to treat the aforementioned oriented substrates and thereby impart or modify their visual, physical and chemical characteristics. Among the various finishing agents are included coloring agents, softening, brightening, lubricating, crosslinking, and anti-static agents among many others.

The term coloring as used herein refers to methods by which color is distributed selectively throughout substrate(-s). The term is used in its generic sense in that it not only includes dyeing where the color (dye) employed has afiinity to the substrate to which it is applied, but also includes pigmenting'where the color (pigment) employed has little or no aflinity for the substrate and which may require the presence of one or more binding agents 3,484,179 Patented Dec. 16, 1969 to promote the adherence of the color to the substrate. Also included are processes not specifically characterized wherein the degree of affinity that the coloring agent(s) possesses for the substrate is intermediate between that of dyes and pigments.

The art of imparting color to fibrous substrates whether by dyeing, printing, staining or pigmenting is of ancient origin. Depending upon various factors such as the substrate employed, its form, the color source, the solvent medium in which substrate and color source are brought together, and the effects sought, the coloring process can range from the most simple to the most complex.

One of the persistent problems connecting with coloring, particularly dyeing is obtaining a desired distribution of color not only upon the yarn surface, but throughout the entire yarn as -well. While ordinarily the desired distribution is one of uniformity, at other times it can be desirable to vary either or both the concentration of color and its distribution to selected portions of the fabric. For example, in some instances it is desirable to color only the warp or weft (fill) yarns or to favor coiled, looped or helical yarns at the expense of others in the fabric. Whatever the desired effect, control of color is essential.

As is well documented in the art, one of the common difficulties inherent to all coloring and finishing processes is removing the excess liquid used as a vehicle for the finishing or coloring agents. This is particularly a problem where more than one type of yarn is present in the fabric substrate and/ or where the physical structure of the yarns differ in shape, weave porosity, thickness or length. In those situations considerable color migration takes place during drying unless moderate and uniform drying is accomplished.

customarily, the removal of excess liquid from the treated fabric is brought about through external heating of the substrate using well established devices such as lofts, ovens, tenters and the like. During this type of drying process it is both difficult and expensive to transfer heat uniformly from an external source to the wet colored woven substrate. Further, since color migration is most pronounced in the areas where drying is most rapid, in conventional drying the color becomes most concentrated near the surface of fabric where drying is most complete.

To overcome uneven drying and the erratic coloring and finishing effects caused by it, a new type of internal heating has been developed and utilized. This type of heating is referred to as dielectric or high frequency drying. In this type of heating the heat is produced by the action of high frequency electrical waves upon a receptive substrate. In dielectric drying a substrate possessing a high dipole moment or containing a substance having a high dipole such as water is placed in close proximity to a high frequency electrical field of alternating polarity generated between electrode sets of two or more electrodes. It is believed that the rapidly oscillating high frequency field passing through the substrate on its path to the electrodes causes the molecules of the substance to vibrate extremely rapidly in accordance with the rapidly reversing polarity of the electrodes. This probably causes substantial internal stress similar to friction stresses that result in heat. Because the electric field creating the stress is uniform throughout the thickness of the substrate the heating is very nearly uniform. Water which is the common vehicle or solvent for textile dyes, colors and finishes has a high dielectric loss factor and is therefore very susceptible to dielectric heating. In contrast most textile fibers have a relatively low dielectric loss factor when dry and are not themselves very susceptible to dielectric heating. Thus, when water evaporation is complete, energy is no longer imparted to the substrate and the drying is more or less self limiting. Therefore dielectric drying otfers the substantial advantages of uniform and rapid drying without significant danger of overdrying.

Formerly, most dielectric drying devices employed plate type electrodes wherein the substrate to be treated is positioned between the electrodes. This type of device is illustrated in FIGURE 1. In this prior art apparatus the primary flow of high frequency energy is directed perpendicular to the plane of the substrate. While efiicient and uniform drying is obtained when a thick substrate is being treated, relatively poor results are obtained when a thin coating, sheet or Web is dried. The reason for this presumably is that the high frequency waves are passed through the substrate at its minimum dimension (its thickness) rather than through its maximum dimension (its warp or weft). For this reason the efficiency of the devices left much to be desired.

To improve the efficiency of dielectric drying devices of the prior art, certain improvements in apparatus have recently evolved to dry uniform web type substrates such as paper which do not possess any warp or weft (fill) orientation. In this type of apparatus illustrated in FIG- URE 2, pairs of tubular electrodes are employed. These electrodes are ordinarily located in a fixed position proximate to the substrate and generate a fixed high frequency field in the direction of the moving paper web parallel to the plane of the paper web. As the length of the paper web is by far the maximum dimension, the high frequency wave energy is directed with maximum efficiency and excellent drying results are obtained.

While the concept of generating a fixed position, high frequency field parallel to the plane of a uniform web represents an advance in the drying of uniform webs, it has little applicability to the much broader technology relating to finishing non-uniform substrates. The differential warp and weft structure of these substrates offers much greater latitude in finishing effects than is possible with uniform substrates such as paper. Unfortunately, both of the described dielectric apparatuses which are illustrative of all the known prior art procedures are limited to the generation of a fixed high frequency field without regard to the rotational orientation of the field to the substrate and therefore do not fully exploit finishing of woven-type substrates or substrates having yarns in transverse direction.

In view of the afore-recited limitations of the known dielectric devices and methods employing them, there is a need for improved methods and devices possessing greater flexibility than is presently available. A minimal requirement is that they lend themselves to differential finishing effects including coloring of weft or warp yarns or selected portions thereof to the partial or total exclusion of the other. Further requirements are that the method utilize either available devices or modifications of these devices to produce a variety of decorative and utilitarian finishes heretofore either unobtainable or obtainable only at considerably higher costs.

Ideally a method could employ a variety of woven-type substrates fabricated from absorbent or non-absorbent yarns or mixtures of these treated with liquid carried finishes. Finally, the finishes produced using this method should be both permanent and reproducible.

A process combining the flexibility and advantages elaborated above would represent a substantial advance in the finishing art.

Recently applicants have developed a dielectric device and unusual techniques for employing it which make possible the various objects enumerated below.

It is a general object of this invention, among others, to develop novel methods of utilizing variable high frequency fields as a means of finishing oriented substrates.

It is another object of this invention to control the migration and deposition of finishing agents including coloring agents during the drying of woven-type substrates treated with liquid carried finishes.

Another more specific object of this invention is the development of a method whereby the above finishing techniques are achieved by changing the direction and intensity of an oscillating high frequency field with respect to the warp and weft (fill) orientation of a woven-type substrate located within that field.

Yet another even more particular object included within the above-described method is changing the direction and/or intensity of an oscillating field vis-a-vis woven- 'type substrate containing finishing agent and liquid while maintaining the high frequecy field parallel to the plane of the substrate. Said change of intensity or direction of th high frequency field can be made one or several times in a continuous or discontinuous fashion. That is, the fields direction can be continuously rotated back and forth within a preset angular range or revolved continuously or discontinuously at the same or different rates of speed through an angular range of zero to 360 to define a complete circle.

Another object of the invention is to position a high frequency field, aligned parallel to the plane of a fabric, treated with finishing agents, to a preselected angle with respect to its yarn orientation to obtain differential effects on the finishes or coloring of said yarns.

Still another object of this invention is to develop a dielectric device capable of generating an oscillating high frequency field and positioning said field in a predetermined direction.

. Additional specific objects of this invention are developing improved methods of dyeing absorbent and non-absorbent fabrics through the aforesaid selective application of the high frequency field waves. Illustrations of these techniques are cross-dyeing or stripping with two or more colors, selective tip dyeing in fabrics containing fibers of differential mass and structure to obtain three-dimensional effects; coloring raised float patterns on flat fabrics with complementary or contrasting colors among others.

Another group of objects of this invention are directed to the control of the application of non-color finishes to woven-type fabrics by the use of controlled applications of high frequency energy. Within this group of objects are included the following specific objects: the application of polyphase finishes to obtain varying finishes on selected portions of the treated fabric, varying the hand on both natural and synthetic fabrics, uniform deposition of protective coatings on fabrics and the like.

Yet an additional group of objects of this invention are best characterized as developing special techniques for drying a variety of heat sensitive substrates. These include, among many others, the drying of wet sized yarn, the rapid drying of adhesive contained in flocked, coated or laminated fabrics, the drying of permanent press type of finishes to a predetermined moisture content, as well as the uniform drying of oriented substrates generally.

Further objects of this invention, both in their process and apparatus aspects will suggest themselves to the reader after a perusal of this disclosure.

The above objects, among many others, are achieved by the process and apparatus to be described more fully below.

' In practice, a strong, orientable high-frequency field is produced by the application of oscillating high frequency voltage between a plurality of electrodes. A woven-type substrate previously treated with one or more finishing agents and liquid carrier(s) is brought within said high frequency field so that thermal energy is imparted to the substrate. Then the high frequency field is oriented in a preselected angular direction varying between the axis defined by the warp and weft yarns. The change in angular direction of the high frequency field can be brought about most conveniently by orienting either the substrate or the position of the electrodes vis-a-vis the substrate.

In the preferred practice the high frequency field maintained parallel to the plane of the substrate is oriented from zero to 90 with respect to the wrap and weft (fill) orientation of the substrate; that is, the application of the high frequency waves can be directed perpendicular to either the warp or weft direction of the substrate or in any intermediate direction. Thus, when the direction of the high frequency waves is parallel to the warp direction it is at 90 with respect to the weft (fill) yarns. Similarly when the field is directed exactly midway between the aXis formed by the warp and weft yarns it can be said to be applied at an angle of 45 to either the warp or the weft yarns.

FIGURES 4, 5, and 6 show diagrammatic illustrations of the application of high frequency energy to the warp of woven-type substrates at angles of 90, 45 and 0 respectively.

The novel device will now be described in greater detail with reference to the accompanying drawings wherein:

FIGURE 1 is a diagrammatic view of a prior art dielectric drying apparatus wherein the substrate to be dried is inserted between stationary plate-type electrodes which generate a fixed high frequency field perpendicular to the plane of the substrate;

FIGURE 2 shows a view of the substrate-electrode arrangement in an improved version of the dielectric device of FIGURE 1. In this version the electrode pairs are positioned proximate to the plane of the web to be dried, so that the generated high frequency field is parallel to the plane of the web and in a fixed position in the direction of the length of the moving web;

FIGURE 3 is a perspective View of a dielectric device illustrating the invention;

FIGURE 3A is a detail showing of the aligning mechanism, and

FIGURE 4 shows the position of the electrode pairs of the device of the invention with respect to the substrate when the high frequency field is generated parallel to the plane of the woven-type substrate at an angle of 90 to the weft (fill) yarn and 0 to the warp yarn of the substrate.

FIGURE 5 shows the relative position of the electrode pairs of the device of the invention with respect to the woven-type substrate when the high frequency field is generated parallel to the plane of the substrate at an angle of 45 to both the warp and weft (fill) yarns of the substrate.

FIGURE 6 shows the relative position of the electrode pairs of the inventive device with respect to the woventype substrate when the high frequency field is generated parallel to the plane of the substrate at an angle of 90 to the warp yarn and 0 to the weft. (fill) yarn of the substrate.

FIGURE 7 shows a schematic view of a continuous finishing operation employing the concept of the invention in which the substrate is given a plurality of separate finishing and dielectric treatments. After each treatment with finishing agent the substrate is passed between banks of independently controlled and separately oriented electrodes so as to effect-the desired deposition of finish upon the substrate.

Apparatus for carrying out the invention is illustrated in an exemplary manner in FIGURE 3. l

The apparatus illustrated comprises three distinct parts, a high frequency source 21, a support means 58 for the substrate and movable banks of electrodes 31.

The electrical source (not shown) sends a flow of current through a standard heavy duty electrical conduit into a high frequency control source 21 containing a suitable rectifier (not shown) and a generator (not shown) capable of generating an oscillating high frequency field ranging from about to about 30,000 kc. or above, whose intensity and continuity can be controlled by the control means 22. v

The high frequency current passes through the leads 23 and'24 and through contact brushes 25 and 26 making contact with conduction rings 27 and 28 on column 29. The current then passes through leads (not shown) concealed in a conventional manner within the column 29 and framework 30 to the electrodes 31. The electrodes 31 of alterating polarity are mounted on a rotatable frame 30 supported by the column 29. The electrode banks are capable of adjustments about a horizontal axis through rotation of column 29 by means of the ring gear 34 mounted on the column 29. Ring gear 34 is engaged by a bevel gear 33 keyed on output shaft 32 from control gear box 35.

A cam roller 38 which is engaged by a removable model cam 39 resting on supports 41, 42 and 43 controls the angular tilt of the electrode bank with respect to the horizontal plane. Cam 39 may be modeled for the dynamic or static tilt desired.

A shaft 44 is slidably mounted within a sleeve 46 set within a base 47. The up and down adjustment of the shaft is controlled by means of a set screw 48. The upper end of shaft 44 is secured to a substrate support 58 which positions and guides the substrate 49 within the high frequency field generated by the electrodes 31.

During use of the above described device the woventype substrate, previously treated with one or more finishing agents contained in one or more liquid carriers is fed by the feed roller 50 over the adjustable support guide rods 58 under the electrodes 31 to the tape-up roller 51. The support guide rods 58 can be adjusted in an upward or downward direction according to whether it is desired to bring the substrate 49 closer or further away from the high frequency field.

The direction of th field is omnidirectional with respect to the warp and fill orientation of the substrate 49 and is changed according to the finishing etfect sought by cranking gear box 35 by means (not shown) until the desired angular change is made. In applications such as drying to a predetermined degree, the control 22 can be used to vary the intensity of the high frequency field applied to the substrate.

To describe the inventive process in the greatest possible detail the following examples are submitted:

EXAMPLE 1 Selective deposition of color to the warp yarns of a glass fabric A sample of an open weave glass fabric comprising a loopy bulk overfeed filling and a continuous yarn warp with the yarns grouped to form a stripe, is dipped in a green pigmented aqueous acrylic latex finish. The formulation of the finish was: 873 gms. of water 2 gms. of morpholine, 60 gms. of ethyl acrylate polymer, 40 gms. of phthalocyanine green pigment and 35 gms. of a plasticizing emulsion, said plasticizing emulsion beiug composed of 200 parts by weight of polymeric epoxide plasticizer, 10 parts by weight of alkylaryl polyether alcohol surfactant and 190 parts of water. The 'pigmented fabric is then squeezed through a hand wringer to remove excess water and placed on a movable belt through an electrostatic field generated by the inventive dielectric dryer shown in detail in FIGURE 3.

The horizontal alignment of the electrodes of the dryer is parallel to the web of the moving wet fabric and the electrodes angular orientation is set so that the high frequency field is directed parallel to the warp fibers or at an angle of to the fill fibers. The arrangement of the electrodes is shown in FIGURE 4. The dried fabric showed concentration of green pigment primarily in the warp yarns only.

EXAMPLE 2 Selective deposition of color in the fill (weft) fibers H of a glass fabric Another sample of the woven-type glass fabric described in Example 1 is dipped in green pigmented acrylic latex and squeezed dry as therein described. However, in this example the electrodes position is turned 90 so that while the generation of the electrostatic field is still parallel to the plane of the fabric, the direction of high frequency waves is parallel to the fill (weft) fibers and at 90 to the warp direction. The position of the electrodes vis-a-vis the orientation of the fabric fibers is shown in FIGURE 6. In this run the green color became concentrated in the fill yarns, particularly in the core of these yarns leaving the loopy bulk overfeed substantially uncolored.

Similar runs are mad maintaining the direction of the high frequency waves as described, except that in these experiments a more closely woven fabric having continuous yarns in the warp and loopy bulk overfeed yarns in the fill are employed. The same selective color deposition effects are obtained.

EXAMPLE 3 Deposition of color equally to both the warp and fill (weft) yarns of a glass fabric Using the same glass fabrics, pigmenting agents, and treatments described in Examples 1 and 2, the electrodes are positioned so that while the generation of high frequency waves is parallel to the plane of the pigmented glass fabric, the waves are applied at 45 to both the warp and weft fibers. This equalizing position is shown in FIGURE 5. At the end of the run both warp and weft (fill) fibers are colored and as before the loops of the looped bulk overfeed yarn remains uncolored.

EXAMPLE 4 Multi-color effects using the inventive process In this experiment the open weave glass fabric with loopy bulk overfeed filling having a continuous yarn warp described in Example 1 is employed. As described therein the deposition of green pigment is concentrated in the warp yarns by orienting the direction of the high frequency field at 90 to the fill yarns.

The dried fabric is then dipped in a red pigmented acrylic-latex and the electrodes position turned 90 so that the high frequency waves are directed parallel to the fill fibers and at 90 to the warp direction as described in Example 2. The resultant fabric comprises red colored fill yarn, green colored warp yarns with the loopy bulk overfeed substantially uncolored.

The bicolored fabric is then treated with a yellow pigmented acrylic latex and dried in a conventional forced air drying oven. The resultant fabric comprises green warp yarns, red fill yarns with yellow looping and is illustrative of the diverse effects obtained using the inventive process.

' EXAMPLE 5 Uniform deposition of color upon oriented glass fabric In this example the glass fabric and pigmenting agents described in Examples 1 to 3, are employed except that two separate sets of electrodes electrically compensated are employed to assure uniform color deposition through out the fabric.

Both sets of'electrodes are aligned parallel to the web of the moving fabric but each set of electrodes is adjusted to give the generated high frequency field different orien tations with respect to the warp and weft (fill) yarns of the fabric. A schematic view of a similar type of electrode alignment is shown in FIGURE 7.

Electrode Set 1 is positioned to direct a high frequency field along the warp yarns (at 90 to the fill) end. Set 2, is positioned to direct a high frequency field along the fill yarns (at 90 to warp). By utilizing sensing probes attached to the warp and fill yarns the flow of high frequency energy along the warp and fill directions is continually decreased or increased so as to compensate for the directional drying bias.

The dried fabric unlike those of Examples 1 to 3, shows a uniform concentration of green pigment throughout the fabric,

8 EXAMPLE 6 Two-color effects obtained using the products of Examples 1 to 3 The color oriented samples of Examples 1 to 3 are overpadded with a yellow acrylic latex pigment and hotair dried to yield fabrics having unique two-color effects.

EXAMPLE 7 Application of the inventive method to cellulosic woven fabrics Sample lweft colored Sample 2both weft and warp colored Sample 3warp colored EXAMPLE 8 Drying cellulosic fabrics treated with heat curable finishing agents This example is illustrative of the controlled self-limiting drying that is possible when a textile fabric pretreated with a heat sensitive finishing agent is dried to a predetermined moisture content using the inventive method. The evolution of the water from the fabric terminates the heating since only the water is heated.

A 50% polyester-50% cotton twill blend is padded with an aqueous padding solution containing 1% by weight of magnesium chloride, 0.5% by weight of citric acid, 12% by weight of N,N-dimethylol dihydroxyethylene urea and 86.5% by weight of water, a heat sensitive crosslinking system used to crease-proof cellulosics and squeezed through a hand wringer to remove excess water.

The drying device of FIGURE 3 is maintained sufficiently proximate to the wet fabric to drive off the water in the fabric without curing the heat sensitive finish. The drying is kept up until a sensing probe indicates that the moisture content of the fabric is about 5% by weight.

After storage at room temperature the dried fabric is fabricated into trousers creased along the warp direction and cured by pressing for seconds on a steam press to set the crease. The excellent initial appearance of the creases and their appearance after several launderings in dicate that little or no curing took place during drying and that the crease is resistant to laundering.

The above example is merely illustrative of one of many heat sensitive modifying systems which can be dried to a predetermined moisture level without curing the finish. Numerous other finishes and fabrics can be employed in an equivalent fashion. A more comprehensive listing of textile substrates with a description of other N-methylol type of crosslinking agents which can be used is disclosed in Ser. No. 545,832 (Pensa), filed Apr. 28, 1966. Other finishing agents which can be employed with comparable results include polyfunctional sulfone reagents such as the vinyl sulfones and their derivatives.

This invention offers several substantial advantages over the prior art in both its methods and apparatus aspects.

For example, prior to the development of this invention no known method was available whereby selective deposition and migration of finishing agents to woventype substrates could be achieved by exposing the substrates containing finishing agents to the controlled effects of an oriented omnidirectional high frequency field. Further, applicants method of varying the direction of the high frequency waves in respect to the warp and weft orientation of the substrate permits selective and mixed color efiects to be obtained using electrical energy to achieve the desired effect. Illustrative effects include multi-color, contrasting color, over-dyeing and striping among others.

In its apparatus aspect this inventions omnidirectional capabilities permit far greater flexibility. in dielectric drying than has been heretofore available with the mono and fixed directional devices of the prior art. Applicants apparatus makes it possible to achieve the selected application of high frequency electrical energy to woventype substrates and to effect differential drying in a manner not previously known.

As the several examples and descriptive text indicate numerous modifications, variations, changes and substitutions can be made in the substrate coloring and finishing agents and effects to be derived, without departing from the inventive concept. The metes and bounds of this invention are best described by the claims which follow.

What is claimed is:

1. A process for obtaining a selected pattern of a finishing agent on a fabric having yarns oriented in at least two directions whereby different concentrations of finishing agent are selectively deposited on the yarns depending on the direction of orientation, said process comprising applying to said fabric a composition containing a finishing agent and a liquid carrier having a high dipole moment, and drying said fabric by heating in an oscillating high frequency electric field which is substantially parallel to the plane of the fabric with the direction of said field being more closely parallel to the yarns in one direction than the yarns in other directions, whereby during said drying the composition migrates to the yarns which are more closely parallel to the direction of the field, causing a greater amount of finishing agent to be deposited on these yarns.

2. A process as claimed in claim 1 wherein said scillating high frequency field is provided by means of a bank of electrodes arranged substantially parallel to said fabric.

3. A process as claimed in claim 1 wherein said liquid carrier is water.

4. A process as claimed in claim 1 wherein said high frequency electrical field has a frequency above about 3,000 kilocycles.

5. A process as claimed in claim 1 wherein said finishing agent is a coloring agent.

6. A process as claimed in claim 1 wherein after said drying a second and different coloring agent is applied to said fabric.

7. A process for obtaining a selected pattern of a finishing agent on a fabric having yarns oriented in two directions perpendicular to each other whereby different concentrations of finishing agent are selectively deposited on the yarns depending on the direction of orientation, said process comprising applying to said fabric a composition containing a finishing agent and a liquid carrier having a high dipole moment, and drying said fabric by heating in an oscillating high frequency electric field which is substantially parallel to the plane of the fabric with the direction of said field being more closely parallel to the yarns in one direction than in the other direction, whereby during said drying the composition migrates to the yarns which are more closely parallel to the direction of the field, causing a greater amount of finishing agent to be deposited on these yarns.

8. A process as claimed in claim 7 wherein the finishing agent is a coloring agent.

9. A process as claimed in claim 7 where in at least one of said directions the yarns include a loopy overfeed, and during said drying the loopy overfeed has deposited thereon a smaller concentration of finishing agent than the other yarns running in the same direction.

10. A process as claimed in claim 7 wherein said oscillating high frequency electric field is provided by means of a bank of electrodes arranged substantially parallel to said fabric.

11. A process as claimed in claim 7 wherein said fabric is a glass fabric.

12. A process as claimed in claim 7 wherein said fabric is a cellulosic fabric.

13. A process as claimed in claim 7 wherein said high frequency electrical field has a frequency above about 3,000 kilocycles.

14. A process as claimed in claim 7 wherein said fabric is woven.

15. A process as claimed in claim 7 wherein said liquid carrier is water.

16. A process for obtaining a uniform deposition of a finishing agent on a fabric having similar yarns oriented in two directions perpendicular to each other, whereby substantially the same concentration of finishing agent is deposited on the yarns in both directions, said process comprising applying to said fabric a composition containing a finishing agent and a liquid carrier having a high dipole moment, and drying said fabric by heating in an oscillating high frequency electric field which is substantially parallel to the plane of the fabric with the direction of said field being at an angle of about to both the directions of the yarns.

17. A process for obtaining a selected pattern of a finishing agent on a fabric having similar yarns oriented in two directions perpendicular to each other and a loopy overfeed in at least one of said directions, whereby substantially the same concentration of finishing agent is deposited on said similar yarns and a lesser concentration is deposited on said loopy overfeed, said process comprising applying to said fabric a composition containing a finishing agent and a liquid carrier having a high dipole moment, and drying said fabric by heating in an oscillating high frequency electric field which is substantially I parallel to the plane of the fabric with the direction of said field being at an angle of about 45 to both the directions of the yarns.

18. A process as claimed in claim 14 wherein said fabric is woven.

References Cited UNITED STATES PATENTS 3,399,460 9/1968 Russell.

2,366,347 1/1945 Millson 82 2,448,009 8/1948 Baker 11793.2 3,293,765 12/1966 Winkler et al. 341 3,340,125 9/1967 Drenning et al. 341

J. E. CALLAGHAN, Assistant Examiner US. Cl. X.R.

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