US3616175A

US3616175A - Chamoislike nonwoven fabric

Info

Publication number: US3616175A
Authority: US
Inventors: Shee Lup Jung
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1969-06-16
Filing date: 1969-06-16
Publication date: 1971-10-26
Anticipated expiration: 1988-10-26

Abstract

Chamoislike nonwoven fabric weighing between 1 and 9 ounces per square yard is produced from a loose web of rayon fibers of up to 1.0 denier per filament maximum by traversing the web with high energy jet streams of water to entangle the fibers and form a strong, durable fabric characterized by a fiber entanglement completeness of at least 0.6 and a fiber entanglement frequency of at least 30 per inch. A substantially nonpatterned appearance is achieved by supporting the web on a fine mesh screen and oscillating the traversing streams. Properties of the fabric are disclosed to be comparable to chamois for wiping water from surfaces.

Description

United States Patent [72] Inventor Shee Lup Jung Wilmington, Del. 21 Appl. No. 833,823 [22] Filed June 16,1969 [45] Patented Oct. 26, 1971 [73] Assignee E. I. du Pont de Nemours & Company Wilmington, Del.

[54] CHAMOISLIKE NONWOVEN FABRIC 5 Claims, 5 Drawing Figs.

52 0.5. CI 161/164, 19/161R,28/72.2,161/169 [51] Int. Cl B32b 5/16 [50] Field of Search 161/164, 169;28/72.2; 19/161 R [56] References Cited UNITED STATES PATENTS 3,485,706 12/1969 Evans 161/72 HIGH PRESSURE WATER SUPPLY Primary Examiner- Robert F. Burnett: Assistant Examiner--Roger L. May Attorney-Norris E. Ruckman ABSTRACT: Chamoislike nonwoven fabric weighing between 1 and 9 ounces per square yard is produced from a loose web of rayon fibers of up to 1.0 denier per filament maximum by traversing the web with high energy jet streams of water to entangle the fibers and form a strong, durable fabric characterized by a fiber entanglement completeness of at least 0.6 and a fiber entanglement frequency of at least 30 per inch. A substantially nonpatterned appearance is achieved by supporting the web on a fine mesh screen and oscillating the traversing streams. Properties of the fabric are disclosed to be comparable to chamois for wiping water from surfaces.

PATENTEBnm 2a 1971 SHEET 10F 2 INVENTOR SHEE LUP JUNG HIGH PRESSURE WATER SUPPLY ATTORNEY PATENTEnnm 26 911 3,616,175

SHEET 20F 2 Fl 6. 4 F s. 5 REFLECTED LIGHT TRANSHITTED LIGHT "are INVENTOR SHEE LUP JUNG ATTORNEY BACKGROUND OF THE INVENTION The present invention relates to nonwoven fabrics which resemble chamois, both in appearance and in the properties that make chamois of outstanding value for wiping water from surfaces.

Adequate strength and stability can be provided in nonwoven fabrics bythe use of binder. However, such nonwoven fabrics have been greatly inferior, particularly in wiping performance and aesthetics to chamois, a leather which combines a soft, smooth texture, high water retention, and ability to wipe a surface without leaving residual water droplets or lint.

SUMMARY OF THE INVENTION The p esent invention provides nonwoven fabrics which compare favorably with natural chamois in wiping ,performance, which have adequate strength and surface stability for usewhile wet and for repeated laundering, and which approximatethe soft, smooth surface and the supple hand-of high quality chamois. Theseproperties can be provided in the chamoislike nonwoven fabrics without the use of resin or other hinder, or fiber-to-fiber fusion bonding. Other objects and advantages of the inventionwill become apparent from thedisclosure and claims.

The products of the present invention are chamoislike nonwoven fabrics consisting essentially of rayon fibers of up to 1.0 denier per fiber maximum (preferably about 075 denier per fiber), which are locked into place by three dimensionalfiber entanglement in a fabric structure characterized by a fiber entanglement frequency (7) of at least 30 per inch and preferably at least70 per inch with a fiber entanglement completeness (7) of at least 0.6, wherein entangled fibers turn, wind, twist back-and-forth and pass about one another inall three dimensions of the structure in so intricate a fashion that fibers interlock with one another when the fabric is subjected to stress to thereby provide strength and durability in the fabric.

The smooth surface texturc anddensely consolidate but soft structure of the above products resemble oil-tanned chamois. The products are generally of lighter weight than chamois, i.e., less than about 9 ounces per square yard. (oz./yd. The products should weigh at least 1 oz./yd. and preferably 2 to 5 oz./yd. The products have a bulkranging from 6 to 13 oz./yd. of weight,whereas chamois has a value ofabout 5 mils per oz./yd. The products have excellent surfacestability and adequate strength for repeated wet use and laundering. They have .the ability to wipe smooth surfaces dry without leaving lint or marks due to dried water droplets, e.g., when wiping automobiles.

The above products are comparable to chamois in wiping water from surfaces. In tests defined subsequently, the products of this invention have a wiping capacity of at least 0.8 gram of water per. gram of fabric, and preferably haying a wiping time of 30 to 55 seconds in a standard drum-wiping test. This test evaluates the ability of a fabric to remove residual droplets of water from a smooth surface so that water spotting will not occur. A standardamount of water is placed on a ground methyl methacrylate wheel, the wheel is revolved and the fabric is held against the wheel until the ,water is completely removed. The transition from a wet to a dry surface is readily seen as a change from a transparent to a translucent surface. Details of the tests are given priorto the exam ples.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying illustrations of theinvention,

FIG. 1 shows a schematic view of one type of apparatus for preparing the nonwoven fabric.

FIG. 2 is a schematic isometric view of an apparatus for high speed continuous production of the nonwoven fabric.

FIG. 3 is a schematic view of apparatus for determining drum-wiping time.

FIG. 4 is a photograph by direct illumination of the face of nonwoven fabric produced as described in Example ll.

FIG. 5 is a corresponding photograph by light transmitted through the same nonwoven fabric.

DETAILED DESCRIPTION The products of the present invention are produced from a fibrous web of rayon fibers of up to 1.0 denier per fiber preferably about 0.75,d.p.f.). The web is supported on a fine mesh screen (60 mesh or finer, and preferably to mesh), or on a solid plate, and is treated with fine columnar water streams at high energy flux per stream and for a suffcient total treatmentenergy to form a strong, coherent nonwoven fabric of highly entangled fibers. The significance of the terms energy flux" and treatment energy" is explained hereinafter. The energy flux should be at least 23,000 ft. poun- .dals/in. second and the energy should be at least 0.1 HP- hr./lb. of treated fabric. In practice, values in excess of this are are used in order to obtain high strength and surface stability withmaximum efficiency. Columnar streams of water issuing from 0.002 to 0.010 inch diameter orifices at waterpressures of at least 200 pounds per square inch gauge (p.s.i.g.) provide sufficient energy flux to obtain good entanglement. Preferably, the web on its support screen is passed under one ormore rows'of streams issuing from closely spaced orifices, e.g. 20 to 40/inch arranged in line in a manifold, using water pressures of 500to 2000p.s.i.g.

In order to prepare products which are suitable for use as chamois it is important that the web and supporting surface for it'be properly selected to get a smooth textured, nonapertured product. Screens of 60 mesh or finer, preferably about 80 to 150 mesh, when used with l to B oz./yd. webs of rayon staple fibers, having a denier of one or less, have been found satisfactory. In general, lower web weights require finer screens as supports-in order to get nonapertured products. Thus, for l oz./yd. webs it is preferred touse screens of about 150 mesh or finer, whereas for a 6 oz.,/yd. web screens down to 60 mesh can be used. Alternatively, a solid, smooth plate or extending in linear paths corresponding to the number and paths of the streams, or a series of closely spaced short curved or straight lines, corresponding to the oscillating frequency of the streamswhen oscillating streams are used. These surface markings, which are only visible on close inspection, in no way detract fromthe smooth, soft texture and nonapertured nature of the product, needed forchamoislike hand and appearance.

It orderto obtain a wiping performance equivalent to or better than chamois, the products of the.;.presentinvention must be prepared from hydrophilic fibers such as rayon. A suitable fiber is commercially available brightor dull rayon, havingan irregular crenulated cross section. Rayon XL, an intermediate high wet modulus rayon, is also suitable and confers high wet strength-withexcellent wiping performance.

A few percent of hydrophobic fibers: may be present in the products of the present invention, but such fibers are preferably excluded, since as little as 10 percent of hydrophobic fiber such as acrylic fiber has been found to reduce wiping performance, especially with respect to the ability to wipe a surface free of residual water droplets.

In order to have the desired aesthetics and adequate surface stability for use as chamois, it is important to prepare the products of thepresent invention from fibers of one denier per filament or lower.

An apparatus for treatment of fibrous sheets is shown in FIG. 1. Water at normal city pressure of approximately 70 lbs/sq. in. gauge 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 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 operating 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 the system through valve 16. Water at the desired pressure is delivered through valve 17 and pipe 18 to manifold 19 supplying orifices 20. The fine essentially columnar streams of water 21 emerging from orifices impinge on the fibrous web 22 being treated, which is supported by conveyor screen 23.

The streams are traversed over the web, by moving the conveyor screen 23 and/or the manifold 19, until the web is treated in the desired areas at high energy flux. In general, it is preferred that the initial fibrous layer be treated by moving conveyor screen 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 nonwoven 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 nonwoven fabrics, may be of steady or 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 sufficiently high energy flux.

Another apparatus suitable for the continuous production of nonwoven fabrics in accordance with the present invention is shown schematically in FIG. 2. A fibrous layer 29, prepared by conventional means, such as random web air-laydown equipment, is supplied continuously to a moving carrier belt 31 of flexible foraminous material, such as a screen or a solid belt. 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 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 treatment of different initial fibrous layers.

In order to obtain the high-strength nonwoven fabrics of the present invention, it is essential that the initial material be subjected to the action of streams of a noncompressible fluid at sufficiently high energy flux and for a sufficient amount of treatment to entangle 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-toweb spacing during treatment. The liquid initially forms a solid" stream, i.e., an unbroken, homogeneous liquid stream. The initial energy flux, in foot-poundals per square inch per second, is readily calculated by the fonnula,

EF, =77 PG/a where: P=the liquid pressure in p.s.i.g.

G=the volumetric flow of the stream in cu. ft./ minute, and

mhe 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-seetional area (a), which is inside the jet device, can be determined by measuring the actual orifice area and multiplying by the discharge coefficient (usually 0.64), 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 rapidly as the stream travels away from the orifice, even when using carefully drilled orifices. The stream diverges to an area (A) just prior to impact 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 flux 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:

E1 =77 PG/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.g. can provide sufficient energy flux for several inches when using a highly efiicient jet device, e.g. as in the Examples.

The high strength, nonwoven fabrics of the present invention can be produced by treating the web with streams of water jetted at sufficiently high pressure and having an energy flux (EF) of at least 23,000 ft.-poundals per inch second. Such streams are preferably obtained by propelling a suitable liquid such as water, at high pressure through small-diameter orifices under conditions such that the emerging streams remain essentially columnar at least until they strike the initial material. By essentially columnar" is meant that the streams have a total divergence angle of not greater than about 5.Particularly strong and surface-stable fabrics are obtained with high-pressure liquid streams having an angle of divergence of less than about 3 degrees.

The amount of treatment must be sufficient and is measured by energy expended per pound of fabric produced. Tl-le 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:

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 cu. ft./min./orifice,

.r =speed of passage of the web under the streams, in

ft./min., 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 imp inged on the material at an energy flux (EF) of at least 23,000 ft.-poundals/in. sec., entangled nonwoven fabrics can be prepared at expenditures of energy of at least about 0.l HP- hr./lb. 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 uses, an energy flux (EF) of at least 100,000 ft.-poundals/in. sec. and a total treatment energy (E) greater than 1 HP-hrJIb. of fabric are preferred.

TESTS FOR EVALUATING PHYSICAL PROPERTIES In table 1 of the examples, strip tensile strength is measured on an Instron tester at 70 F. and 65 percent relative humidity, using a sample 0.5 inch wide, a sample length of 2 inches, and elongating at 50 percent per minute.

Surface stability is determined by laundering in an agitator washing machine using a cotton setting and drying in a tumble dryer for 5 cycles. Test samples are mixed with cotton cloths to yield a standard load. The samples are rated subjectively for surface stability on a scale of 5 (surface stability unaltered by test) to 1 (sample falling apart or pilling extremely badly).

Web thickness is measured using an Ames thickness gauge and a pressure of 0. l 5 p.s.i.

DRUM-WIPING TEST FIG. 3 illustrates the apparatus used for measuring drum wiping time. The apparatus consists of a wheel or drum 51, having aradius of 4 inches and a wiping surface 5 inches wide, the surface being of ground methyl methacrylate. The drum is rotatably mounted on a shaft carrying pulley 52 which is engaged in driving relationship with pulley 53 of a conventional motor (not shown) to rotate the drum at a rate of 45 revolutions per minute. Fixedly mounted above drum 51 is a friction clamp 54 adapted to hold the test specimen so that it drapes over the surface of drum 51 in contact with one-fourth of the circumferential distance of the drum as shown by arrow 55. In operating the test, a 2- or 4-ply sheet or web 56, which is 4X12 inches or longer is mounted in clamp 54 to maintain a 90 overlay on the drum surface as shown at 55 and is held against the drum surface by a weight 57 of 320 grams which is clamped at the opposite end of the sheet. For webs 2 oz./yd. or less, the 4-ply sheet is obtained by cutting a l2 l6-inch sample and folding it into fourths (4 layers, each 4X12 in.). For samples greater than 2 oz./yd. the test specimen is a 2- ply sheet obtained by cutting an 8X 1 2-inch sample and folding it in half (2 layers, 4X12 in.). Samples are folded in the machine direction, if there is one. After folding, samples are pressed. with a steam iron and clamped to the tester at 54. Prior to running the test for each sample, the drum is sanded with very fine (400)sandpaper, wiped with a damp towel and dried with a paper towel. Using a hypodermic needle (1 cc. capacity), 0.6 cc. of water is deposited in a line (about 0.75 inch wide) across the top of the drum spreading to within oneeighth inch of each edge of the drum. The dry sample is then draped gently and quickly over the drum, and the drum and stop watch are started simultaneously. The drum surface not covered by fabric is observed, using a light shining directly on the drum, and as soon as the surface turns from transparent to translucent, the watch is stopped and the time (in seconds) recorded to dry the drum is reported as the drum-wiping time.

WATER RETENTION Another important property which chamois exhibits is the ability to pick up and retain moisture. The products of the present invention are compared with chamois under three conditions to simulate end-use. For all three test conditions, sample size is 14 in. X 16 in., folded to 4 plies for samples weighing more than 2 oz./yd. and 14 24 in. folded to 6 plies for samples weighing 2 ozJyd. or less.

In order to test water retention under no load condition, which gives a measure of the product's ability to sop up water, folded samples are soaked in water for at least 5 minutes, placed on an inverted funnel and allowed to drain freely for 30 seconds before weighing. Precautions against cupping of this fabric are taken to avoid trapped water and to insure free drainage.

To test water retention under light load" condition, which simulates wet wiping, samples are folded to a 4-inch nip width; soaked at least 5 minutes in water and passed twice through an Atlas electric wringer (Model LW-l) with a 20-lb. load, corresponding to 5 lb./in. pressure. Samples are tested in 4 thicknesses if the dry weight is more than 2 oz./yd. and in 6 thicknesses if they weigh 2 oz./yd. or less when dry.

Water retention is then tested under heavy load" condition, which simulates medium hand-wringing of a wet fabric, and reflects the wiping ability of the fabric after having been wrung out. The procedure is the same as for the light load condition, except that a weight of pounds is used, corresponding to 25 lb./in. wringer pressure.

Samples are weighed after each test. The water retention under each of the three conditions is expressed as grams of water per gram of fabric.

WIPING CAPACITY Wiping capacity, which is also a measure of the ability of a chamois to remove droplets of water from a smooth polished surface without leaving tracks, can be calculated from the difference between the water retention values of a damp, justwrung fabric and a fabric which has picked up sufficient water during wiping to just begin to leave tracks of water. These conditions have been found to correspond to an electric wringer load of 25 lb./in. and 5 lb./in., respectively. Wiping capacity is therefore the difference between the water retention values measured at 25 lb./in. and 5 lb./in., respectively, and is expressed in grams of water per gram of fabric.

A comparison of the water retention properties of the nonwoven fabrics of the present invention. with chamois fabric is given in table I of the examples. As: may be seen, wipingcapacity of the products of the present invention ranges from 0.9 to 1.2 grams of water per gram of fabric as compared with 0.4 to 0.7 gram of water per gram of chamois.

ENTANGLEMENT FREQUENCY AND COMPLETENESS TESTS In these tests, nonwoven fabrics are characterized according to the frequency and the completeness of the fiber entanglement in nonbonded fabric, as determined from strip tensile breaking data using an lnstron" tester.

Entanglement frequency is a measure of the frequency of occurrence of entanglement sites along individual lengths of fiber in the nonwoven fabric. The higher the value of entanglement frequency 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 is a measure of 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.

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

lnstron In cutting the strips from fabrics having a repeating pattern of ridges or lines ofhigh 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. Ten or more specimens are tested at w,, and five or more at w and w, using an lnstron" tester with standard rubber coated, flat jaw faces and the gauge lengths and elongation rates listed above. Average tensile breaking forces for each width 0, w,, w; are correspondingly reported as T,,, T,, and T It is observed that. l 2 T0 It is postulated that the above inequalities occur because:

1. there is a border zone of width D at the cut edges of the long gauge length specimens, which zone is ineffective in carrying stress; and

2. with zero gauge length, fibers are clamped jaw-to-jaw and ideally all fibers carry stress up to the breaking point, while with long gauge length, some poorly entangled fibers slip out without breaking. A measure of the proportion of stress-carrying fibers is called 0. Provided that D is less than 1/2 w,, then:

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 90 to the direction specified in (a) In unpatterned fabrics any two directions at 90 will suffice. c and D are determined separately for each direction and the arithmetic means of the values for both directions, E and D, are calculated. ?-is called the entanglement completeness. The reciprocal of D is called the entanglement frequencyfper inch.

When is greater than 0.5, fis a measure of the average distance required for fibers in the fabric to become completely entangled so that they cannot be separated without breaking. When is less than 0.5, it has been found that Tmay be influenced by factors other than entanglement. Accordingly, when c'is less than 0.5, calculation ofTas described above may not be meaningful.

In certain cases, D may be nearly zero and even a small experimental error can result in the measured D being negative. 1f the measured D turns out to be zero or negative, it is proper to assume that the actual Dis less than 0.01 inch and that Tis greater than 100 per inch.

The following examples, which illustrate preparation of certain preferred chamoislike products of the present invention, are not intended to be limitative.

EXAMPLE I This example illustrates preparation of a nonwoven synthetic chamois from a 3 oz./yd." web of randomly disposed fibers of rayon XL 1.0 d.p.f. and about 1.6 inches long).

The web is prepared by air deposition to form a random web and is hydraulically entangled, using apparatus of the type described previously. The jet manifold used has 0.005-inch diameter orifices drilled in a single line at a spacing of 40 orifices/inch. The orifices are carefully cleaned and bored to get as sharp an entry into the orifice as possible to minimize any breaking up of the stream issuing from the orifices. Uniformity of water distribution to the orifices is facilitated by use of a screen in the manifold approximately 0.25 inch above the orifices. The manifold is oscillated at approximately 300 r.p.m. Treatment consists of moving the web, supported on an 80 mesh (i.e., 80x80 wires/inch) screen having 16 percent open area, under the streams of water issuing from the manifold, while spaced three-fourth inch from the orifices, at a speed of 1 yd./min., for 4 treatment passes, the lst pass being at 200 p.s.i.g. water pressure, the 2nd at 500 p.s.i.g., and the 3rd and 4th at 1500 p.s.i.g. The sample is then removed from the screen, turned over and placed (treated side down) on a 150 mesh screen, having an open area of 37 percent, and treated with 5 passes under the streams, the 1st at 200 p.s.i.g., the 2nd at 500 p.s.i.g., the 3rd at 1000 p.s.i.g., and the 4th and 5th at 1500 p.s.i.g. All treatment passes are in one direction. Energy flux, under maximum pressure conditions of 1500 p.s.i.g. is 22.4)( ft.-poundals/in. sec. The total energy expended is 9.17 HP-hr./lb. The nonwoven fabric thus obtained is then dyed with Color Index Direct Brown 25 (Color lndex 36030) to obtain the desired chamois color. The properties of the fabric are shown in table 1. It has superior surface stability when laundered.

EXAMPLE 11 This example illustrates preparation of a nonwoven synthetic chamois from a 4 ozJyd. web of randomly disposed fibers of rayon XL (0.75 d.p.f., about 1.6 inches).

The web is prepared by air deposition to form a random web and is hydraulically entangled to form a nonwoven fabric, using the processing conditions of Example 1 except the passes are as follows:

On mesh screen, 16% open area Maximum energy flux used in the treatment is 22.4Xl0 ft.- poundals/inFsec. Total energy expended in the treatment is 6.86 l-lP-hr./lb.

Tl-le properties of this fabric are given in Table 1. It is more dense than the fabric of Example 1 and has better surface stability upon laundering and better chamoislike aesthetics. The fabric is shown at 10X by reflected light in FIG. 4 and by transmitted light in P16. 5. The view using transmitted light shows the slight trace pattern resulting from the oscillation of the jet streams of liquid, the oscillating frequency of the jets being approximately 300 rpm.

EXAMPLE 111 This example illustrates preparation of a nonwoven, synthetic chamois from a web of nominal weight of 1.5 oz./yd. of randomly disposed fibers of rayon XL (1 d.p.f., about 1.6 inches).

Two such webs are prepared by air deposition technique. One web is treated with essentially columnar streams of water while supported on an 80 mesh screen of 16 percent open area (Sample A). The second is treated on a mesh screen of 37 percent open area (Sample B).

Each web is hydraulically entangled by treatment with jet streams using a manifold having 0.005-inch diameter orifices drilled in a single line at a frequency of 20 orifices per inch. The manifold is oscillated at approximately 300 r.p.m. The orifices are about 0.75 inch above the web during treatment. Three passes are used; during the first pass, the web is covered with a screen having 16x18 wires/inch and 70 percent open area; conditions are:

The total energy expended in the treatment is 3.15 l-lP-hn/lb. Maximum energy flux used in the treatment is 16 10 ft.- poundals per inch -sec.

The products are very similar in their properties as can be seen from table 1 and have good wiping ability and chamoislike aesthetics.

EXAMPLE v A similar fabric is prepared as in example IV except that the second treatment involves passage of the web under all five manifolds as in the first treatment; total energy expended for both treatments is 3.8 HP-hr./lb. This fabric is subsequently dyed and then characterized; it has the following properties:

EXAMPLE IV This example illustrates continuous production of a nono 2 woven synthetlc chamols. i' i 2 b f d 1 dis d fb rs Th1ckness(m||s) 3| An lnlnal 3 y we 9 ran p l e 7 Surface Stability (first face) 3.3 prepared on layer forming equipment, 1s fed continuously to Surface Stability (second face) 4.8 the treatment. The web is prepared from 1.0 d.p.f., about 1.6 T z s g 4 5 inch long rayon XL. The supporting screen used is an 80 mesh XD screen of 31 percent open area. Two treatment passes are Fiber Entanglement Completeness a 0.139 used, both run at 3 yds./min. Processing involves subjecting Fiber Entanglement Frequency 545 the web to (1) one pass under a line of 0.007 inch diameter orifices, spaced /inch (manifold A) to wet the web and TABLE 1 Strip tensile strength Water retention Bulk Surface Fiber en- (g. water/g. Drum (mils stability (lb/in)/ tanglement fabric) Wiping wiping Weight Thickper (ozlyd l values capacity time (02/ V ness 02/ is! 2nd Example A B C (B-C) (see) yd (mils) yd face face: MD XD F f 2.8 1.8 1.0 40 3.1 24.6 7.9 3.3 3.2 0.97 126 2.7 1.8 0.9 39 4.0 25.4 6.4 3.7 3.7 0.72 100 2.8 1.9 0.9 52 1.6 19 12 4.4 3.0 1.8 1.2 2.0 18 9 4.9 0.98 100 2.8 1.6 1.2 3.5 32 9.1 3.3 40 4.11 4.0 1.6 1.2 0.4 9.1 47 5.2 5.6 3.1 Chamois 2... 2.1 1.4 0.7 9.4 45 4.8 5.0 5.0 10.5 6.7 Chamois 3 7.5 2.2 L5 0.7 54

a Representative value; determined on a different sample of chamois. A=Noload B=5 lbs/in. C= lbs./ in.

prevent bubbling and distortion of the web, and (2) one pass under each of 4 successive manifolds (B, C, D, and E), each having a single line of 0.005 inch diameter orifices, spaced /inch. Web-to-orifice spacing during treatment is approximately 0.25 inch. Water pressures in the successive five manifolds are 400, 800, 1000, 1550, and 1500, respectively. Fabric thus treated is passed under the jets in a second treatment, in which the jets act on the reverse side of the web, so that both sides of the web receive treatment. In the second treatment, only manifolds A, B and D are operated so that the web is treated at 400, 800 and 1500 p.s.i.g., successively. An energy of 1.9 HP-hr./lb. of fabric is expended in treating the first side and 0.9 HP-hr./lb. for the 2nd side of the fabric. Energy flux of the streams at the maximum pressure, 1550 p.s.i.g. is 23.5X10 ft.-poundals/in. sec. The nonwoven fabric thus obtained is then subjected to a 10-minute scouring in boiling dye solution in an autoclave and a 4-minute rinse in a home washing machine. This treatment serves to impart softness and naplike surface as well as to dye the fabric to a chamois color. The dye solution contains 1 percent Color Index Direct Orange 59, 2 percent Color Index Direct Yellow 50 (Color Index No. 29025), and 0.1 percent Color Index Direct Brown 25 (Color Index No. 36030) and approximately 0.1 percent of a sodium salt of technical lauryl alcohol sulfate, based on the weight of the fabric. Properties of the fabric are given in table 1. The product is a drapeable nonwoven fabric with a naplike surface and a soft hand closely resembling chamois. In use, the nonwoven fabric is found to be easier to wring free of water than a chamois and when used to wipe a highly polished surface, such as an automobile, it leaves no lint and no water marks on the surface. It also performs well as a damp wiping cloth for cleaning glass surfaces. There is less tendency to stick to the surface while wiping than when using chamois; since the product has a lower coefficient of friction when wet than chamois has, wiping is easier.

I claim:

1. A nonwoven fabric having a chamoislike hand and appearance, weighing between 1 and 9 ounces per square yard, consisting essentially of rayon fibers of up to 1.0 denier per filament maximum, and having the fibers locked into place by three-dimensional fiber entanglement in a fabric structure characterized by a fiber entanglement frequency of at least 30 per inch with a fiber entanglement completeness of at least 0.6, wherein entangled fibers turn, wind, twist back-and-forth and pass about one another in all three dimensions of the structure in so intricate a fashion that fibers interlock with one another when the fabric is subjected to stress to thereby pro vide strength and durability in the fabric.

2. The nonwoven fabric defined in claim 1 wherein the 55 fabric weighs from 2 to 5 ounces per square yard and has a bulk of 6 to 13 mils thickness for each ounce per square yard of weight.

3. The nonwoven fabric defined in claim 1, characterized by a wiping capacity of at least 0.8 gram of water per gram of fabric and a wiping time of 30 to 55 seconds in the standard gram of water per gram of fabric, having a wiping time of 30 to 55 seconds in the standard drum-wiping test, and having sufficient durability to withstand repeated laundering in a laundry machine.

Claims

2. The nonwoven fabric defined in claim 1 wherein the fabric weighs from 2 to 5 ounces per square yard and has a bulk of 6 to 13 mils thickness for each ounce per square yard of weight.
3. The nonwoven fabric defined in claim 1, characterized by a wiping capacity of at least 0.8 gram of water per gram of fabric and a wiping time of 30 to 55 seconds in the standard drum-wiping test.
4. THe nonwoven fabric defined in claim 1, having a soft, smooth texture with a substantially uniform surface appearance.
5. A nonapertured, nonwoven fabric having a chamoislike hand and appearance, consisting essentially of rayon staple of about 0.75 denier per filament, weighing from 2 to 4 ounces per square yard, having a bulk of 6 to 13 mils thickness per oz./yd.2 of weight, having a wiping capacity of at least 0.9 gram of water per gram of fabric, having a wiping time of 30 to 55 seconds in the standard drum-wiping test, and having sufficient durability to withstand repeated laundering in a laundry machine.