US3486168A - Tanglelaced non-woven fabric and method of producing same - Google Patents

Description

Dec. 23, 1969 F. J. EVANS ET AL 3,486,168

TANGLELAGED NON-WOVEN FABRIC AND METHOD OF PRODUCING SAME Filed Dec. 1. 1966 4 Sheets-Sheet 1 F/GZ I8 HIGH PRESSURE WATER SUPPLY INVENTORS FRANKLIN JAMES EVANS RONALD JOHN SUMMERS .w ATTORNEY Dec. 23, 1969 F. J. EVANS ET AL 3,486,168

TANGLELACED NON-WOVEN FABRIC AND METHOD OF PRODUCING SAME Filed Dec. 1, 1966 4 Sheets-Sheet 2 F I G. 5

FIBER ARRAYSA TANGLELACED RIBS TAIIGLELACED RIBS INVENTORS FRANKLIN JAMES EVANS RONALD JOHN SUMMERS MZM ATTORNEY Dec. 23, 1969 F. J. EVANS ET A TANGLELACED NON-WOVEN FABRIC AND METHOD OF PRODUCING SAME 4 Sheets-Sheet 3 Filed Dec. 1, 1966 FIG.

FIG.

FIG?

i.|25 mcHl |.|25 mcrH FRANKLIN JAMES EVANS RONALD JOHN SUMMERS INVENTORS ATTORNEY Dec. 23, 1989 F. J. EVANS ET AL 3,486,168

TANGLELACED NON-WOVEN FABRIC AND METHOD OF PRODUCING SAME File d Dec. 1, 1966 4 Sheets-Sheet 4 0.2 INCH INVENTORS FRANKLIN JAMES EVANS' RONALD JOHN SUMMERS ATTORNEY TANGLELACED NON-WOVEN FABRIC AND METHOD OF PRODUCING SAME Franklin James Evans and Ronald John Summers, Wilmington, Del., assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Dec. 1, 1966, Ser. No. 598,256

Int. Cl. B32b 5/16 US. Cl. 161-169 9 Claims ABSTRACT OF THE DISCLOSURE Nonwoven fabric having an appearance and properties analogous to conventional woven corduroy, grosgrain or poult textile fabrics. They can be produced from a loose mass of textile staple by depositing the fibers randomly in a layer, supporting the layer on a suitable patterning member and applying a high energy treatment with liquid streams of very small diameter formed at unusually high pressures. The fibers are strongly entangled into ribs positioned over valleys or slots in the patterning member. Upon removal from the patterning member, the products are useful for textile purposes without further treatment.

This invention relates to nonwoven fabrics having a ribbed appearance and having sutficient strength to be used as fabric without need for adhesive bonding.

In the past, conventional weaving techniques have been employed in order to make ribbed fabrics, such as corduroy, grosgrain or poult textile fabrics. The present invention provides a nonwoven fabric whose appearance simullates that of conventional ribbed fabrics but whose fiber arrangement is uniquely different.

More particularly, the products of the present invention are nonwoven fabric having a regular pattern of substantially continuous and parallel ribs of tanglelaced fibers, the ribs running one major direction of the fabric and being interconnected with one another by generally parallel individual fiber segments which extend in a substantially continuous array between adjacent ribs and are preferably approximately perpendicularto the ribs. The ribs may be straight, or may follow an undulating path along the fabric at a uniform spacing from adjacent ribs.

Preferred nonwoven fabrics of this invention weigh from 2 to 10 oz./yd. and have from 3 to 30 ribs per inch.

By tanglelaced or tanglelaced area, as used herein, is meant a type of random, three-dimensional fiber interentanglement whereby the fibers are locked into position in the fabric by fiber interaction alone, that is, without the need for binders or other supplementary bonding treatment. This fiber interaction is so complex and random that special methods of characterizing the tanglelaced areas have been devised. According to these methods, the tanglelaced nonwoven fabrics of thi invention are characterized by having an entanglement frequency (f) of at least per inch and an entanglement completeness (c) of at least 0.5. A relatively simple test nited States Patent O "ice which may be employed as a preleminary screening test involves determining the resistance of the entangled region to penetration by a needle under standard conditions. According to this test, tanglelaced products have an impenetrability raitng (I) of a least 0.5. Preferred products also have a structural measure of fiber entanglement and cooperation (S) of at least 0.1. All of these tests are conducted on nonwoven fabrics which contain no binder and which have not been bonded by any other known technique such as fusion-bonding (heat and/or pressure) or the like. The tests are described in greater details near the end of the specification.

By a substantially continuous array of individual fiber segments is meant that segments of individual fibers extend between the ribs and are closely spaced with respect to one another so as to define a fabric continuum between the ribs. In other words, the fiber segments between ribs are not arranged in any definite groupings or the like which would form a distinct pattern of apertures between the ribs.

The individual fibers of the fabric proceed randomly from tanglelaced rib to tanglelaced rib and are locked into place at the tanglelaced ribs. The arrangement of fibers in the fabric of the present invention is such as to form flexible hinges between the ribs of the fabric. Because of these hinge fibers, the ribs may be moved longitudinally with respect to one another whereby the nonwoven fabric has conformability and drape similar to that attained by bias stretch in conventional woven fabrics.

The nonwoven fabrics of the present invention can be prepared from bulk fibrous material by depositing the fibers in a layer, supporting the layer on certain types of patterning members and then subjecting the material to essentially columnar streams of liquid, such as water, issuing from small orifices at pressures, in pounds per square inch, of 200 psi or greater to form fine liquid streams having an energy flux of at least 23,000 footpoundals per square inch per second and continuing the treatment to provide sufficient energy to tanglelace the fibers of the nonwoven fabric. The processing conditions and equipment will be discussed in greater detail hereinafter.

The patterning member preferably should have a topography comprised of parallel ridges alternating with depressions (valleys or slots). Treatment of the fibrous material on the patterning member causes the major proportion of the fibers to be moved into the valleys or slots, where the fibers are compacted and entangled with one another to form the tanglelaced ribs of the fabric. The remaining fiber segments are pulled taut over the tops of the ridges to form the array of generally parallel fiber segments extending between tanglelaced ribs. Tanglelacing is observed to be at a maximum along the border Where the rib joins the parallel fiber segments. The surface of the patterning member preferably consists of a series of flat bars or strips arranged parallel to and equally spaced from one another to form a grill-like element having no crossing members at the surface Where patterning occurs. Alternatively, a grill of parallel wires may be used. For continuous production a grooved or slotted roll is preferred. If desired, woven wire screens, prepared to provide the indicated topography of high and low areas, may be used to form the ribbed products of this invention.

The tanglelaced ribs form in the area between parallel bars, and their breadth may be increased as desired by increasing the spacing between bars and/ or by increasing the weight (oz./yd. of the initial fibrous material. Similarly, the distance between ribs, i.e., the length of the fiber segments between the tanglelaced ribs, may be increased by increasing the thickness of the parallel bars and/or by decreasing the weight of the fibrous material. If desired, the parallel bars may have a top surface which is tapered whereby the fibers will more readily move into the spaces between bars in response to the action of the liquid streams. Obviously, the bars cannot be spaced too far apart or too close together for a given weight of fibrous material. Preferably, the bars are spaced at a frequency of 3 to 30 bars per inch for initial fibrous materials weighing from 2 to 10 oz./yd.

The initial fibrous material may be any web, mat, batt or the like of loose fibers disposed in random relationship with one another or in a degree of alignment. If carded batts or other webs of aligned fibers are used, they are preferably positioned on the grill with their fibers running perpendicular or at an angle to the bars of the grill since the alignment of the fibers of the carded batt parallel to the bars may excessively increase the tendency for the fibers to be driven into the spaces between bars when acted on by the streams, leaving no interconnecting fibers between ribs.

The term fiber as employed herein is meant to include all types of fibrous materials, whether naturally or synthetically produced and whether of staple lengths or longer, including continuous filaments and blends of fibers of different types (material, length, and/ or denier). Additional bulk and density may be imparted to these fabrics by preparing them from fibers which have a latent ability to undergo crimping, shrinking or elongating and subsequently developing the latent properties of the fibers. Other specialty fabrics may be made by employing elastic fibers or highly crimped fibers. Inclusion of 30 to 50% of short fibers 4 inch or less) is preferred for improved surface stability.

The invention will be better understood from the accompanying illustrations wherein,

FIGURE 1 is a schematic view of apparatus suitable for preparing the fabrics of this invention.

FIGURE 2 is a schematic isometric view of an apparatus for high-speed continuous production of the fabncs.

FIGURE 3 is an edge view of a portion of one type of patterning member used in preparing the fabrics, with a portion of the fabric shown positioned as prepared on the member.

FIGURE 4 is a schematic representation of the same fabric in plan view.

FIGURE 5 is a photograph of a portion of the fabric prepared as described in Example I. The face shown is the face which is impinged on by the streams during final processing (i.e., upstream face).

FIGURE 6 is a photograph of fabric prepared as described in Example IV. The face shown is the face which is adjacent the patterning member during final processing (i.e., downstream face).

FIGURE 7 is a photomicrograph (the magnification being as indicated by the scale) showing in plan view the upstream face of fabric prepared as described in Example V.

FIGURE 8 is a photomicrograph of the fabric shown in FIGURE 7 (at the same magnification) but photographed by light transmitted through the fabric to show the arrangement of fibers.

FIGURE 9 is a photomicrograph (at the magnification indicated by the scale) showing an enlarged crosssection taken on line 9-9 of FIGURE 6, i.e., with the fabric cut perpendicular to the ribs. It shows the arrangement of fibers in 2 ribs and the nature of the interconnecting fiber segments. The photograph shows that in this fabric, entanglement is at a maximum along the border where the rib joins the generally parallel fiber segments.

FIGURE 10 shows the cross-section of FIGURE 9 further enlarged.

FIGURE 11 is a plan view of the undulating grill used as patterning member in Example VI.

FIGURE 12 is a photomicrograph (magnification as indicated) of fabric prepared as described in Example VI. The upstream face of the fabric is shown.

PROCESSING CONDITIONS In order to obtain the high-strength patterned, tanglelaced products of the present invention, it is essential that the initial material be subjected to the action of streams of a non-compressible fluid at suificiently high energy flux and for a sufficient amount of treatment to pattern and tanglelace the fibers thereof. The energy flux (EF) of the streams will depend upon the jet device used, the pressure of the liquid supplied to the jet orifice, and the orifice-to-web spacing during treatment. The liquid initially forms a solid stream, i.e., an unbroken, homogenous liquid stream. The initial energy flux, in footpoundals per square inch per second, is readily calculated by the formula,

EF =77PG/a where:

P=the liquid pressure in p.s.i.;

G=the volumetric flow of the stream in cu. ft. per minute;

and

a=the initial cross-sectional area of the stream in square inches.

The value of G for use in the above formula can be obtained by measuring the flow rate of the stream. The initial cross-sectional area (a), which is inside the jet device, can be determined by measuring the actual orifice area and multiplying by the discharge coefiicient (usually 0.64 to 0.80), or it can be calculated from measured flow rates. Since the area (a) corresponds to solid stream flow, the above formula gives the maximum value of energy flux which can be obtained at the pressure and fiow rate used. The energy flux will usually decrease as the stream travels away from the orifice, even when using carefully drilled orifices. The stream diverges to an area (A) just prior to impace against the web and the kinetic energy of the stream is spread over this larger area. The cross-sectional area (A) can be estimated from photographs of the stream with the web removed, or can be measured with micrometer probes. The energy fiux is then equal to the initial energy flux times the stream density ratio (a/A). Therefore, the formula for energy flux at the Web being treated is EF :77PG/A ft.-poundals/in. sec.

The value of (A) increases with the orifice-to-web spacing and, at a given treatment distance, the value depends upon the jet device and the liquid supply pressure used. A pressure of 200 p.s.i. can provide sufficient energy flux for several inches when using a highly efiicient jet device. With other jet devices, the energy flux of a stream may become too low in a relatively short distance even when using higher pressures, due to the stream breaking up and losing its columnar form. When this occurs, there is a sudden increase in the value of (A) and the energy flux drops rapidly. Since the stream may become less stable when higher pressures are used, the energy flux at a given treatment distance may actually decrease when the jet orifice pressure is increased to provide a higher initial energy flux (PG/a). Some stream density (a/A) and energy flux determinations of water streams from drilled-tube orifices, of types which are suitable, are given in the following tables. The values for the orifices used in the examples were actually higher than those given in the table.

ENERGY FLUX VALUES FOR DRILLED TUBE ORIFICES Distance below orifice For 7 mil orifice diameter inch inch 1.5 inch 200 p.s.i.:

Stream density (a/A) 0.357 0.125 0. 0563 Energy flux 400, 000 140, 000 63, 000 500 p.s.i.:

Stream density (rt/A) 0.281 0. 097 0.037 Energy flux 1, 225, 000 421, 000 162, 000 1,000 p.s.i.:

Stream density (a/A). 0. 235 0.079 0. 0195 Energy flux 2, 910, 000 072, 000 242, 000 1,500 p.s.i:

Stream density (a/A) 0. 236 9. 0645 0.0125 Energy flux 5, 350, 000 1, 460, 000 283, 000

Distance below orlfice For 5 mil orifice diameter inch inch 1.5 inch 200 p.s.i.:

Stream density (a/A). 0. 2-11 0.103 0.0785 Energy flux 270,000 115, 000 88,000 500 p.s.i.:

Stream density (a/A). 0. 214 O. 0763 0.0565 Energy flux 930, 000 330, 000 250, 000 1,000 p.s.i.:

Stream density (a/A) 0.190 0. 0595 0. 0108 Energy flux 2, 340, 000 730, 000 130, 000

In order to tanglelace the fibers, the streams impinged on the fibrous layer must have an energy flux of at least 23,000 foot-poundals per square inch per second and, in order to avoid excessive treatment times, the streams should be formed by jetting liquid from orifices at high pressure. For example, a practical minimum is treatment equivalent to that provided at a 3inch distance by essentially columnar streams from orifices 0.005 inch in diameter when supplied with water at a pressure of at least 200 pounds per square inch above atmospheric pressure. Preferably, water pressures of 500 to 5000 p.s.i. (35.2 to 352 kg./cm. are used for orifices 0.003 to 0.007 inch (0.0076 to 0.0178 cm.) in diameter with orifice-to-fiber spacing ranging from substantially to 4 inches (0 to 10.2 cm.), although greater pressures and spacings can be used. Lower water pressures can be used at closer spacings. Water at 0 to 100 C. is suitable.

By essentially columnar is meant that the streams have a total divergence angle of not greater than about 5 degress. Particularly strong and surface-stable, tanglelaced, patterned fabrics are obtained with high-pressure fluid streams having an angle of divergence of less than about 3 degrees. The use of essentially columnar streams provides the further advantage of minimizing air turbulence at the surface of the web during processing.

It has been found that low-energy-flux diffuse sprays of water, such as the sprays which emerge from conventional, solid-cone spray nozzles at throughputs of up to 5 gallons/minute (18.9 l./min.) and water pressures of up to 150 p.s.i. (10.5 kg./cm. are unsuited to prepare the patterned, tanglelaced products of the present invention inasmuch as they lack sufiicient energy flux and because they entrain large amounts of air, thereby generating a high degree of air turbulence at the surface of the web. High air turbulence leads to non-uniformities in the final product. A web may be protected from air turbulence by interposing a woven wire screen or other foraminous member at the surface of the web between the web and the source of the stream, but this has an undesirable secondary effect of further lowering the energy flux at the Web surface. Thus, for example, a conventional, solid-cone spray nozzle, having a divergence angle of 22 and issuing water at about 1 gallon/ minute at a water pressure of 100 p.s.i., exerts an energy flux (EF) of 670 ft. poundals/ in. sec. at a distance of about 4 inches from the nozzle. If a ZOO-mesh screen is interposed between such a spray and the web being treated, the energy flux (EF) is reduced to 305 ft.-poundals/in. sec. The products of the present invention cannot be prepared using such sprays.

The process of the present invention may be used to produce patterned, tanglelaced textiles from any type of loose fibrous web, batt, or sheet. The ease with which a given web can be patterned and tanglelaced is dependent upon many factors, and process conditions may be chosen accordingly. For example, webs of low density may be processed more easily than comparable Webs of higher density. Fiber mobility also has a bearing on the ease with which a web can be processed. Factors which influence fiber mobility include, for example, the density, modulus stiffness, surface-friction properties, denier and/ or length of the fibers in the web. In general, fibers which are highly wettable, or have a high degree of crimp, or have a low modulus or low denier, can also be processed more readily.

If desired, the initial fibers or layer may be treated first with a wetting agent or other surface agent to increase the ease of processing, or such agents may be included in the fluid stream.

Depending upon the nature of the initial fibrous layer and the pattern to be produced, the energy flux exerted by the fluid streams may be adjusted as desired by varying the size of the orifices from which the streams emerge, the pressure at which the non-compressible fluid is delivered, the distance the web is separated from the orifices, and the type of orifice. Other process variables, which may be manipulated in order to achieve the desired patterning and tanglelacing, include the number of times the Web is passed into the path of the streams, and/ or the directions in which the web is passed into the path of the streams.

The amount of treatment must be sufficient and is measured by the energy expended per pound of fabric produced. The energy (E) expended during one passage under a manifold in the preparation of a given nonwoven fabric, in horsepower-hours per pound of fabric, may be calculated from the formula:

E =0.125(YPG/sb) Where:

Y=number of orifices per linear inch of manifold,

P=pressure of liquid in the manifold in p.s.i.g.,

G=volumetric flow in cut. ft./min./ orifice,

s=speed of passage of the Web under the streams, in

ft./1nin., and

b=the Weight of the fabric produced, in oz./yd.

The total amount of energy expended in treating the web is the sum of the individual energy values for each pass under each manifold, if there is more than one.

When treating fibrous material with streams of water impinged on the material at an energy flux (EF) of at least 23,000 ft.-poundals/in. sec., patterned, tanglelaced nonwoven fabrics can be prepared at expenditures of energy of at least about 0.2 HP-hr./1b. of fabric. At any given set of processing conditions, surface stability of the nonwoven fabric obtained (i.e., the resistance of the fabric to surface pilling and fuzzing) can be improved by increasing the total amount of energy (E) used in preparing the fabric. For products with sufficient surface stability to Withstand repeated launderings, such as might be required for certain apparel and other uses, an energy flux (EF) of at least 100,000 ft.-poundals/in. sec. and an energy (E) greater than 1 HP-hr./lb. of fabric are preferred.

Webs ranging from 0.5 oz./yd. or less to about 10 oz./yd. or more and composed of natural, cellulosic, and/ or wholly synthetic fibers, can be readily converted into patterned fabrics through the use of water as the fluid and process conditions within the following ranges:

Orifice size inch 0.003 to 0.030 Orifice spacing do 0.01 to 0.1 Water pressure p.s.i. 200 to 5000 Web to on'fice separation inches to 6 Number of passes l to 100 EQUIPMENT A relatively simple form of equipment for treating fibrous webs with water at the required high pressure is illustrated in FIGURE 1. Water at normal city pressure of approximately 70 pounds per square inch (p.s.i.) (4.93 kg./cm. is supplied through valve 1 and pipe 2 to a high-pressure hydraulic pump 3. The pump may be a double-acting, single-plunger pump operated by air from line 4 (source not shown) through pressure-regulating valve 5. Air is exhausted from the pump through line 6. Water at the desired pressure is discharged from the pump through line 7. A hydraulic accumulator 8 is connected to the high-pressure water line 7. The accumulator serves to even out pulsations and fluctuations in pressure from the pump 3. The accumulator is separated into two chambers 9 and 10 by a flexible diaphragm 11. Chamber 10 is filled with nitrogen at a pressure of one-third to two-thirds of the desired operat ing water pressure and chamber 9 is then filled with water from pump 3. Nitrogen is supplied through pipe 12 and valve 13 from a nitrogen bottle 14 equipped with regulating valve 15. Nitrogen pressure can be released from system through valve 16. Water at the desired pressure is delivered through valve 17 and pipe 18 to manifold 19 supplying orifices 20. Fine, essentially columnar streams of water 21 emerge from orifices 20 and impinge on the loose fibrous web 22 supported on patterning member 23.

The streams are traversed over the web, by moving the patterning member 23 and/ or the manifold 19, until all parts of the web to be treated are patterned and tanglelaced at high energy flux. In general, it is preferred that that initial fibrous layer be treated by moving patterning layer 23 under a number of fine, essentially columnar streams, spaced apart across the width of the material being treated. Rows or banks of such spaced-apart streams can be utilized for more rapid, continuous production of tanglelaced fabrics. Such banks may be at right-angles to the direction of travel of the web, or at other angles, and may be arranged to oscillate to provide more uniform treatment. Streams of progressively increasing energy flux may be impinged on the Web during travel under the banks. The streams may be made to rotate or oscillate during production of the patterned, tanglelaced fabrics, may be of steady of pulsating flow, and may be directed perpendicular to the plane of the Web or at other angles, provided that they impinge on the web at sufiiciently high energy flux.

Apparatus suitable for use in the continuous produc tion of tanglelaced, patterned fabrics in accordance with the present invention is shown schematically in FIG- URE 2. A fibrous layer '29, prepared by conventional means such as a card machine or random web air-laydown equipment, is supplied continuously to a moving carrier belt 31 of flexible foraminous material, such as a screen. The carrier belt may also be the patterning member or, as illustrated, the patterning member 30, in this case a grid of parallel bars, may be supplied with the fibrous layer so that changes can readily be made in the pattern. The carrier belt is supported on two or more rolls 32 and 33 provided with suitable driving means (not shown) for moving the belt forward continuously. Six banks of orifice manifolds are supported above the belt to impinge liquid streams 34 on the fibrous layer at successive positions during its travel on the carrier belt. The fibrous layer passes first under orifice manifolds 35 and 36, which are adjustably mounted. Orifice manifolds 8 37, 38, 39 and 40 are adjustably mounted on frame 41. One end of the frame is supported for movement on a bearing 42, which is fixed in position. The opposite end of the frame is supported on oscillator means 43 for moving the frame back and forth across the fibrous layer to provide more uniform treatment.

High pressure liquid is supplied to the orifice manifolds through pipe 18. Each manifold is connected to pipe 18 through a separate line which includes flexible tubing 44, a needle valve 45 for adjusting the pressure, a pressure gage 46, and a filter 47 to protect the valve and jet orifices from foreign particles. As indicated on the gages in the drawing, the valves are adjusted to supply each successive orifice manifold at a higher pressure, so that the fibrous layer 29 is treated at increasingly higher energy flux during travel under the liquid streams 34. However, the conditions are readily adjusted to provide the desired patterning and tanglelacing treatment of different initial fibrous layers.

For preparing the ribbed products of the present invention, it is preferred to use a manifold having a greater number of orifices per inch than the number of ribs per inch in the final product. It is also preferred, during successive passes of the assembly under the streams, to have the orifices arranged so that the streams of successive passes do not coincide. This may be done by staggering the orifices in successive manifolds or by oscillating the manifolds.

AFT ER-TREATMENTS The patterned tanglelaced fabrics prepared in accordance with the present invention may be dried while still on the apertured backing member or after removal from it. They are stable, coherent, strong and ready for textile use. If desired, they may be dyed, printed, heat-treated, or otherwise subjected to conventional fabric processing. Thus, for example, they may be treated with resins, binders, sizes, finishes and the like, surface-coated and/ or pressed, embossed, or laminated with other materials, such as foils, films, or the like.

UTILITY The products of the present invention have many applications. Thus, they may be employed in the same uses as are conventional woven or knitted fabrics. Typical applications include apparel, linings, home furnishings, upholstery and other decorative materials, tarpaulins, padding and/or insulating materials, covering materials, and the like. They may be laminated to similar sheets or to different materials. Interesting packaging materials are made, for example, by laminating patterned, tanglelaced fabrics to metal foils or films. The patterned, tanglelaced fabrics may be cut into strips, if desired, and twisted into yarns. The high strength, patterned, tanglelaced fabrics are particularly suited for industrial applications such as bagging materials, reinforcing materials for rubber or other goods such as belting or tires, and the like. The patterned, tanglelaced productshaving high drape and conformability are eminently suitable for use in clothing, including outerwear such as 'suits, jackets, shirts, blouses and the like.

TESTS FOR EVALUATING PHYSICAL PROPERTIES In the following examples, the tensile properties are measured on an Instron-tester at 70 F. and 65% relative humidity. Strip tensile strength is determined for a sample 0.5-inch wide, using a 2-inch sample length and elongating at 50% per minute. The 5% s'ecant modulus is determined by American Society for Testing and Materials Standards E661, part 10, page 1836. Other test methods are described in detail after the examples.

Example I This example illustrates the preparation of a 3.3 oz./yd. (112 g./m. ribbed fabric having 14 ribs per inch (5.5/cm.).

The initial material is a 2.9 oz./yd. (98 g./m. web of randomly disposed fibers prepared by an air-layering technique. The web contains 50% by weight of 1.5 denier per filament, 1.5 inch (3.8 cm.) acrylic fiber and 50% by weight of 1.5 denier per filament, 0.25 inch (0.63 cm.) acrylic fiber.

The web is placed on a grill-like patterning member having 14 bars/inch (5.5/cm.) and having 44% open area. Each bar is 0.040-inch (0.102-cm.) thick and there is a separation between adjacent bars of 0.031 inch (0.079 cm.). The web/ grill assembly is passed at about 2 yds./min. (1.82 m./min.) under columnar streams of water issuing from a manifold having 0.007 inch (0.0178 cm.) diameter orifices arranged in line at a density of 20 orifices/inch (7.9/cm.). During treatment," web-toorifice spacing is about 0.75 to 1 inch (1.9 to 2.54 cm.). The assembly is passed under the line of streams with the bars of the grill being at 90 to the line of orifices. The water pressure is adjusted to 600 p.s.i.g. (42.2 kg./cm. gauge) for the first pass and 1500 p.s.i.g. (105.7 kg./cm. gauge) for the second. The web is then removed from the grill, turned over, replaced on the grill in registry with the pattern, and passed under the streams once at 600 p.s.i.g. (42.2 kg./cm. gauge) and twice at 1500 p.s.i.g. (105.7 l g./cm. gauge) The resultant product is removed from the grill and air dried It is a ribbed, nonapertured, coherent nonwoven fabric with tanglelaced ribs running in one direction, the ribs being interconnected by an array of generally parallel fiber segments running substantially perpendicular to the ribs. The fabric has a pleasant hand and has the following properties:

Weight (on/yd?) Strip tensile strength (lb /z 4. 1 3.4 Elongation (percent) 47. E) 43.0 5% Secant Modulus (lb./in.//oz./yd.) 8.4 5. 5 Structural measure of entanglement and cooperation (S) 0.12 Impenetrability rating (I) 1.0 Entanglement completeness 0. 76 Entanglement frequency (f) 61 NOTE-11D measurements are in the direction of the tanglelaced ribs; XD measurements are 90 thereto.

This example illustrates preparation of a nonwoven fabric having 12 ribs/ inch and weighing about 5 oz./yd.

The initial material is a 4.75 oz./yd. (161 g./rn. web of randomly disposed fibers prepared by an air-laying technique.

The web contains 65% by weight polyethylene terephthalate fibers of 1.5 denier per filament and 1.5 inch (3.8 cm.) length and of polyethylene terephthalate fibers of 1.5 denier per filament, 0.25 inch (0.63 cm.) length.

The web is placed on a grill-like patterning member having 12 bars/inch (4.7/cm.) and having 52% open area. Each bar is 0.060-inch (0.152-cm.) thick and there is a separation between adjacent bars of 0.023 inch (0.058 cm.). The web/ grill assembly is passed at about 1 yd./ min. (0.91 m./min.) under columnar streams of water issuing from a manifold having 0.007-inch (0.0178-cm.) diameter orifices arranged in line at a density of 20 orifices/inch (7.9/cm.). During treatment, web-to-orifice spacing is about 0.75 to 1 inch (1.9 to 2.54 cm.). The web/ grill assembly is passed under the line of streams with the bars of the grill being at 90 to the line of orifices. The assembly is passed under the streams once at each of 600 and 1000 p.s.i.g., after which it is turned over and then 10 treated once at each of 600, 1000 and 1500 p.s.i.g. The resultant product is removed from the grill and air dried. It is a drapable, highly compacted, strong ribbed nonwoven fabric having the following properties:

MD XD Nora-MD measurements are made in the direction of the ribs; XD measurements are thereto.

The fabric is similar in appearance to that of Example I.

Example III This example illustrates preparation of a nonwoven fabric having 14 ribs/inch (5.5/cm.) and weighing about 3 oz./yd. (101 g./m.

The initial material is of the type and fiber composition as used in Example I and weighs 3.0 oz./yd. (101.5 g./m.

The web is placed on a grill-like patterning member having 14 bars/ inch (5 .5 cm.) and having 44% open area. Each baris 0.040 inch (0.102 cm.) thick and there is a separation between adjacent bars of 0.031 inch (0.079 cm.). The web/ grill assembly is passed at'about 1.5 yds./ min. (1.37 m./min.) under columnar streams using the same type of manifold, the same web-to-orifice spacing and the same direction of passage as in Example I. The assembly is passed under the streams once at each of 600 and 1500 p.s.i.g. (42.2 and 70.4 kg./cm. gauge), after which the sample is turned over, placed on the grill in registry with the pattern and treated once at each of 600, 1000, and 1500 p.s.i.g. (42.2, 70.4, and 105.7 kg./cm. gauge). The product is then removed, air dried and tested. It has 14 distinct, parallel, tanglelaced ribs per inch connected by fiber segments which are generally parallel to one another and perpendicular to the ribs. Fabric properties are:

NorE.MD measurements are made in the direction of the ribs; XD measurements are 90 thereto.

Example IV This example illustrates preparation of a very dense nonwoven fabric having 12 ribs/inch (4.73/cm.) and weighing about 7 oz./yd. (2.37 g./rn. The fabric is shown in FIGURE 6. Cross-sectional views are shown in FIGURES 9 and 10.

The initial material is a 5.5 oz./yd. (186 g./m. web of randomly disposed fibers prepared by an air-laying technique. The web contains 50% by weight of polyethylene terephthalate fibers of 1.5 denier per filament and 1.5- inch (3.8-cm.) length and 50% of high-shrinkage polyethylene terephthalate fibers of 1.5 denier per filament and 0.25-inch length. The high-shrinkage fibers are capable of shrinking about 30% in length when subjected to atmospheric steam or heat C.).

The web is placed on the same type of grill described in Example II (12 bars/inch or 4.73/cm.). The web/ grill assembly is passed at about 1 yd./min. (0.91 m./min.) under coulmnar streams using the same type of manifold as in Example 11. Web-to-orifice spacing and direction of passage are as in Example I. Treatment consists of 1 pass at each of 500 and 1500 p.s.i.g. (35.2 and 105.7 kg/cm. gauge), after which the web is turned over on the grill in registry with the pattern and treated once at 600 Weight (on/yd!) Strip tensile strength (lb./in.//oz./yd. Elongation (percent) 5% Secant modulus (lb./in.//z./yd. Structural measure of entanglement a cooperation (S) Impenetrability rating (I) Entanglement completeness (c) Entanglement frequency (f) Example V This example illustrates preparation of a ribbed non- Woven fabric having 8 ribs/inch (3.15/cm.) and weighing about 3.0 oz./yd. (101.5 g./m.

The initial material is a 3.1 oz./yd. (105 g./m. web of randomly disposed fibers prepared by an air-laying technique. The web contains 50% by weight of 1.5 denier per filament, 1.5 inch (3.8 cm.) acrylic fibers and 50% of 1.5 denier per filament, 0.25 inch (0.63 cm.) rayon fibers.

The web is placed on a grill-like patterning member having 8 metal bars/inch (3.15/cm.) and having 50% open area. Each bar is -inch thick and /z-inch high (0.063 cm. by 1.27 cm.) and there is a separation between adjacent bars of inch (0.063 cm.). The web/grill assembly is passed at about 1 yd./min. (0.91 m./min.) under columnar streams of water issuing from a manifold having 0.005-inch (0.0127-cm.) diameter orifices arranged in line at a density of 40 .orifices/ inch (15.8/cm.). During treatment, web-to-orifice spacing is 1.0 inch (2.54 cm.). The assembly is passed under the line of streams with the bars of the grill being at 90 to the line of orifices. Water pressures and passes are as follows: 500 p.s.i.g. (35.2 kg./cm. gauge) 1 pass, 1500 p.s.i.g. (105.7 kg./cm. gauge) 1 pass. A top screen is placed over the web during the first pass at 500 p.s.i.g. to help hold the web in place. The nonwoven fabric obtained has 8 tanglelaced ribs/ inch and the following properties:

Weight (om/yd?) Strip tensile strength (lb./1 Elongation (percent) 5% Secant modulus (lb./in.//oz./yd. 2. Entanglement completeness (c) Entanglement frequency (f) Example VI This example illustrates preparation of a fabric having an undulating rib pattern.

A grill consisting of A -inch (0.158-cm.) wide bars, arranged at a density of 7 bars/inch (2.76 bars/cm.) is used as patterning member. The bars are crimped or undulated at a frequency of approximately 1.6 crimps/ inch (0.63 crimp/cm.) and amplitude of approximately 0.1 inch (0.25 cm.). The grill is shown in FIGURE 11.

A 4 oz./yd. (135 g./m. web of randomly disposed fibers made on air-laydown equipment is placed on the grill. It contains a 50/50 blend of polyethylene terephthalate fibers (1.5 denier per filament, 1.5 inch, i.e., 3.8 cm. long) and rayon fibers (1.5 denier per filament, 0.25 inch, i.e., 0.63 cm. long).

The web/grill assembly is passed under streams of water issuing from 0.007-inch (0.0178-cm.) orifices,

arranged in line in a manifold at a frequency of 20/inch (7.9/cm.). Three passes are used, each at 1 yd./min. (0.91 m./min.), the pressures at each pass, respectively, being 500, 1000 and 1500 p.s.i.g. (35.2, 70.4 and 105.7 kg./cm. gauge). During treatment, the web/ grill assembly is spaced about 1 inch from the orifices, the general direction of the bars of the grill being at to the line of orifices.

The fabric obtained has an undulating rib pattern, the ribs being interconnected by generally parallel fiber segments. The upstream face of the fabric is shown in FIGURE 12. The structural measure of the entanglement and cooperation (S) is 0.11 and the impenetrability rating (I) is 1.0. Other properties are as follows:

MD XD Weight (on/yd?) 3.8 Strip tensile strength (lb./in.//oz 1. 9 1. 35 Elongation (percent) 56 $0 5% Secant modulus (lb./in.//oz./yd. 2. 9 I. 8

Example VII This example illustrates fabrics prepared at low and high rib densities and web weights.

Two fabrics are prepared using as the initial material for each a web of randomly disposed fibers prepared by air-laying. The fibers are 1.5 denier per filament, 1 inches (4 cm.) rayon fibers. The initial web weights and the patterning grills used for each are given below:

Web Grill Weight Sample (oz./yd. Bars/inch Percent open area A 10. 5 4 74 B 2. 0 30 to Sample A-1000, 1500, sample is then turned over on grill in registry with pattern direction and treated at 1000, 1500, 1500 and 1500 p.s.i.g.

Sample B--600, 1250, sample is then turned over on grill in registry with pattern direction and treated at 600 and 1500 p.s.i.g.

For both samples, a top screen (14 x 18 wires/ inch, 76% open area) is placed over the web during the first and third passes to help hold the web in place and is then removed during the remainder of the treatment. The samples are then removed from the grills, dried and tested. Properties are:

Sample A Sample B MD XD MD XD Ribs/inch 3. 8 33 Weight (on/yd?) 9.9 2.4 Strip tenslle strength (lb./in.//oz./yd. 4. l 4. 5 5.6 5. 5 Elongation at break (percent) 50 '46 53 -14 5% Secant modulus (lb./in.//oz./yd. 10.4 5 4 7.1 7A Entanglement completeness (c) 1. 0 1. 1 Entanglement frequency (f) 41 53 TESTS FOR CHARACTERIZING TANGLELACING All of the products of the present invention discussed above are characterized by the presence of localized regions of tanglelaced fibers which serve to lock the fibers in place and provide strength and coherency to the structure. In the tanglelaced regions, there is a high concentration of fibers and/or fiber segments which are in a tightly packed, highly interentangled relationship wherein fibers randomly turn, wind, twist back-and-forth and pass about one another in all three dimensions of the structure, both individually and severally, so as to be virtually inseparable.

Although the fibers have highly complex, random, three-dimensional configurations in the tanglelaced regions, these structures can be characterized by special tests which have been developed.

IMPENETRABILITY RATING The impenetrability test is based on one common characteristic of tanglelaced regions, that the entanglement holds the fibers together so that they resist separation. In this test, regions are tested for ability to withstand penetration by a needle under standard conditions. The impenetrability rating (I) is the ratio of the number of regions which pass the test to the total number of regions tested. The impenetrability rating (I) for the products of this invention is at least 0.5, i.e., at least onehalf of the test regions pass, when tested in the bondfree state. This is a simple screening test for resistance to separation of fibers, but this property may also be found in some products which are not tanglelaced, or which have only small, widely separated tanglelaced regions that do not provide adequate strength and coherency.

When determining the impenetrability rating (I), the fibers must not be adhered with binder or inter-fiber fusion bonds. The needle has a shank about 0.015 inch (0.038 cm.) in diameter with a conical point having sides making an angle of about 26 with the axis. The needle is held by a pin vise, the total weight of the assembly being about 24 grams. This is used in conjunction with a support plate, %52 inch (0.078 cm.) in thickness, having a series of holes of different diameters drilled in it. These holes are suitably marked for diameter-identification.

To obtain an impenetrability rating (I), a section of the fabric is marked so as to delinate a representative region containing 25 circular areas along the entangled ribs, the diameters of the circles being selected to be equal to the width of the ribs. The average diameter of the entangled areas is estimated with a hand comparator and the specimen is placed on the above-mentioned plate, so that for hydraulically processed fabric the fabric face upstream to the fluid stream during final processing is adjacent the plate and the selected entangled area is placed over a plate-hole having a diameter approximately 75% of the diameter of the entangled area being tested. For other fabrics, either face may be used. For testing entangled areas which are smaller in diameter than about 133x the needle-shank diameter, the entangled area may be placed over a platehole having a diameter slightly larger than that of the needle shank. A light source under the plate-hole and suitable optical magnification are used to assist in achieving the correct placement over the hole. The needle is placed vertically above the entangled area in a central position. The weight of the needle assembly is then allowed to rest on the entangled area by lightly supporting the assembly with the hand to keep the needle vertical. Record is kept of whether it is penetrated or not, using 25 tests as the standard sample. The impenetrability rating (I) is the ratio of the number of entangled areas not penetrated to the total number tested. This test allows for the variation in entanglement in the various areas in a given sample and provides the average fraction of representative entangled areas which will not be penetrated. The highly entangled areas in the products of the present invention have an impenetrability rating of at least 0.5.

ENTANGLEMENT FREQUENCY AND COMPLETENESS In preferred tests, nonwoven fabrics are characterized according to the frequency (f) and the completeness (c) of the fiber entanglement in non-bonded fabric, as determined from strip tensile breaking data using an Instron tester.

Entanglement frequency (f) is a measure of the extent of fiber entanglement along individual lengths of fiber in the nonwoven fabric. The higher the value of (f) the greater is the surface stability of the fabric, i.e., the resistance of the fabric to the development of pilling and fuzzing upon repeated laundering.

Entanglement completeness (c) is the proportion of fibers that break (rather than slip out) when a long and wide strip is tested. It is related to the development of fabric strength. A completeness (c) rating of 1 means that all of the fibers are being utilized in the development of fabric strength.

The products of the present invention have an entanglement frequency (f) of at least 20 per inch and an entanglement completeness (c) of at least 0.5.

Entanglement frequency (f) and completeness (c) are calculated from strip tensile breaking data, using strips of the following sizes:

Strip Strip Instron Elongation width width gauge rate symbol (in.) length (in.) (in/min.) wu 0. 8 0 0. 5 W1. O. 3 1. 5 5

For patterned fabrics, strips are cut in two directions: (a) in the direction of pattern ridges or lines of highest basis weight (i.e., Weight per unit area), and (b) in the direction at to the direction specified in (a). In unpatterned fabrics any two directions at 90 will sutfice.

In cutting the strips from fabrics having a repeating pattern of ridges or lines of high and low basis weight, integral numbers of repeating units are included in the strip Width, always cutting through the low basis weight portion and attempting in each case to approximate the desired widths (W W W2) closely. Five specimens of width W0, ten of width W1 and five of width W2 are tested, using an Instron tester Wtih standard jaw faces and the gauge lengths and elongation rates listed above. Average tensile breaking forces for each width (W W and W are correspondingly reported as T T and T It is Observed that:

w,215 w221) wo and D and C are:

From testing various specimens, it is observed that when (c) is greater than 0.5, the value D/\/d/1.5, where d is the effective fiber denier, is a measure of the average distance required for fibers in the fabric to become completely entangled so that they cannot be separated without breaking. This value is practically independent of 1 5 fiber length. The reciprocal of the value is the entanglement frequency (f) per inch, i.e.,

If the fabric contains fibers of more than one denier, the effective denier (d) is taken as the weighted average of the deniers.

Both (0) and (f) are determined in both major directions as defined above, and the geometric means are reported as the proper values. In any determination of (f), if (1) turns out to be negative this is equivalent to a very high entanglement frequency and (f)=100 per inch is taken as the value to be used. When (0) is less than 0.5, it has been found that (D) and hence (f) may be influenced by factors other than entanglement. Accordingly, when (0) is less than 0.5, calculation of (f) as described above is not meaningful.

STRUCTURAL MEASURE OF ENTANGLEMENT The structural measure of fiber entanglement and cooperation (S) provides a numerical rating of the frictional engagement and interaction of fibers in tanglelaced areas serving to lock the fibers in place, and of the cooperation under stress of fibers extending between tanglelaced areas. These are the important structural features involved in the strength of the fabric. The method of evaluation is based on the proportion of the total fiber weight which is concentrated in the tanglelaced regions, the density of these regions, and the extent to which region-interconnecting fibers have free lengths greater than that of straight line interconnections.

Structurally, the extent of fiber interentanglement is related to the concentration of fibers in the interentangled area (C) and the density of the interentangled mass (d). The product of those two factors provides a measure of the frictional engagement and interaction of the fibers in the interentangled area serving to lock the fibers in place in the fabric to thereby permit maximum utilization of fiber strength when the fabric is subjected to stress. Also, influencing maximum utilization of fiber strength is the cooperation under stress exhibited by the group of fibers which extends between any two entangled areas, which cooperation is inversely related to the average-free-length factor of the individual fibers in the group (F). The structural measure of entanglement and cooperation (S) is defined as the value for non-bonded fabric given by the equation:

The fiber concentration factor (C) is the ratio of the length of fiber actually in the entangled area to the length which would be there ift here were no patterning and/ or entanglement of the fibers, i.e., if the fibers of the fabric were uniformly distributed in the plane of the fabric. Since there is a direct relation between fiber length and fiber weight, the fiber concentration factor (C) may also be described as the ratio of the weight per unit area of the entangled portion (W to the weight per unit area of the entire fabric (W i.e.:

W and W are determined from the fabric sample by suitable measurements. For W a representative entangled rib section is dissected out of the fabric with scissors and is weighed on a suitable balance. For fabrics having straight ribs, a section of rib about 1.8 cm. long is used. For fabrics having undulating ribs, a number of straight sections are cut out of the ribs so as to total 1.8 cm. in length. The areas of the dissected sections are measured directly for use in determining W Alternatively, C can be approximated from a photograph at about 10X of the fabric using diffuse bottom lighting and measuring the average widths of the entangled ribs and repeat units. Assuming that the major proportion of fiber is concentrated in the rib, it is possible to show that C is approximately equal to the ratio of the width of the repeat unit of the pattern in the fabric to rib width.

The density (d) of the entangled mass can be measured by calculating the volumes of the cut-out specimens mentioned above. To do this, the specimens are mounted on broaches and are photographed at 5 to 10X to provide cross-sectional data. The cross-sections, thus determined, are averaged and, using the appropriate geometric formulas, the corresponding volumes are calculated. The total weight of the specimen or specimens is then divided by the volume or the sum of the volumes of the specimens to give the average density (d) in grams per cubic centimeter of the entangled ribs.

The average free-length factor (F) of the fibers in the group extending between any two entangled areas is estimated by direct observation (under a microscope) of the fibers in the group and comparison to a set of standards. The fiber group is observed both in plan view and in cross-sectional view, the latter being from a specimen cut along the group and viewed edge-on. The five ratings used as standards and the corersponding curvatures and free lengths are shown below.

CHART FOR ESTIMATING FREE LENGTH If, for example, the fibers in the group on the average are visually estimated to have a curvature such that the ratio of the deviation from straightness (h) to the halflength in the group observed (hl) is about 0.5, then a rating of 3 is assigned. Such estimates are made three times independently, and averaged both in the plane of the fabric and normal to or out of the plane (cross-section). The two estimates are then combined geometrically by taking the square root of half the sum of the squares of the two ratings. If F is the estimated in-plane rating and F is the estimated out-of-plane rating, the average free-length factor (F) is:

In practice, it is observed that structures made from straight (i.e., non-crimped or non-curled) fibers do not have ratings of one (corresponding to no curvature). Instead, there is always some free length and an appropriate class rating which may be used for structure made from straight fibers is F=l.4. Similarly, it is observed that the rating for samples made from conventional staple fibers or low crimp continuous filaments ranges from 1.8 to 2.5. For such fibers, an average class rating of F=2.1 may be used. For highly crimped fibers, the estimated values of F should be used.

Preferred products of the present invention, where the entangled regions are discrete ribs, have values of at least 0.1 for the structural measure of fiber entanglement (S) in the regions of highest fiber entanglement and fiber cooperation in the structure.

LAUNDERABILITY The unique tanglelaced structure of the products of the present invention is also evident from the launderability of these products. Thus, the highly tanglelaced, patterned fabrics of the present invention, in the absence of binder, can be laundered in conventional, household washing machines and dried in conventional driers with out loss of their utility as a fabric.

Since many different embodiments of the invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited by the specific illustrations except to the extent defined in the following claims.

We claim:

1. In the production of nonwoven fabric from loose fibrous material by treatment with streams of liquid from jet devices, the process for for producing tanglelaced fabric having a ribbed appearance which comprises supporting a.

layer of the fibrous material on a patterning member having a topography of parallel ridges alternating with depressions, jetting liquid supplied at pressures of at least 200 pounds per square inch to form fine, essentially columnar, liquid streams having over 23,000 energy flux in foot-poundals per square inch per second at the treatment distance, traversing the supported layer of fibrous material with the streams to entangle a majority of the fibers into ribs positioned over the depressions of the patterning member and to pull the remaining fibers taut over the tops of the ridges of the patterning member, and treating the supported layer with the streams until a patterned, tanglelaced fabric is produced having parallel ribs running in one direction of the fabric and interconnected with one another by generally parallel individual fiber segments which extend in a substantially continuous array between adjacent ribs and are locked into place in the ribs by tanglelacing wherein fibers turn, wind, twist backand-forth, and pass about one another in all three dimensions of the structure, so as to be virtually inseparable and provide strength and coherency to the structure.

2. The process defined in claim 1 wherein the layer of fibrous material is treated with the liquid streams while supported on a patterning member having a surface consisting of equally-spaced parallel bars to form a tanglelaced fabric having the appearance of conventional, woven, corduroy fabric.

3. The process defined in claim 2 wherein the bars are spaced at a frequency of 3 to 30 bars per inch and the layer of fibrous material weighs from 2 to ounces per square yard.

4. The process defined in claim 1 wherein the layer of fibrous material is treated with the liquid streams while supported on a patterning member having a surface consisting of parallel bars which undulate in the plane of the surface to form a tanglelaced fabric having an undulating rib pattern.

5. The process defined in claim 1 wherein the layer of fibrous material is treated with the streams until a total of at least 0.2 horsepower-hours of stream energy per pound of treated fabric is provided.

6. A textile-like tanglelaced fabric having a ribbed appearance, which comprises (a) substantially parallel ribs of randomly entangled fibers, the ribs being substantially continuous and running in one major direction of the fabric, and (b) generally parallel individual fiber seg ments interconnecting the ribs in the other fabric direction, the fiber segments extending between adjacent ribs in a substantially continuous array and being locked into place in the ribs by tanglelacing; said fibers of the fabric locked into position by a three-dimensional fiber interentanglement characterized by a fiber entanglement frequency of at least 20 per inch with a fiber entanglement completeness of at least 0.5; and wherein fibers in said ribs turn, Wind, twist back-and-forth, and pass about one another in all three dimensions of the structure, so as to be virtually inseparable and provide strength and coherency to the structure.

7. The fabric defined in claim 6 wherein the ribs are spaced at a frequency of 3 to 30 ribs per inch and the fabric Weighs from 2 to 10 ounces per square yard.

8. The fabric defined in claim 7 wherein the ribs are straight and uniformly spaced.

9. The fabric defined in claim 7 wherein the ribs follow an undulating path along the fabric at a uniform spacing from adjacent ribs, the fabric having an undulating rib pattern.

References Cited UNITED STATES PATENTS 2,862,251 12/1958 Kalwaites 161109 X 3,214,819 11/1965 Guerin 2872.2

ROBERT F. BURNETT, Primary Examiner ROGER L. MAY, Assistant Examiner US. Cl. X.R.

Dedication 3,486,168.Fmnlclin James Evans and Ronald John Summers, \Vilmington, Del. TANGLELACED NON-WOVEN FABRIC AND METHOD OF PRODUCING SAME. Patent dated Dec. 23, 1969. Dedication filed Mar. 29, 197 6, by the assignee, E. I. du Pont de Nemours and Company. Hereby dedicates to the Public the entire remaining term of said patent.

[Ofiicial Gazette May 25, 1.976.]

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