US3193436A - Nonwoven fabric - Google Patents

Description

F. KALWAITES NONWOVEN FABRIC July 6, 1965 2 Sheets-Sheet 1 Filed July 22, 1960 Will IN VEN TOR. Fran fifdwaz'fes H TTOE/VE Y5 F. KALWAITES NONWOVEN FABRIC July 6, 1965 2 Sheets-Sheet 2 Filed July 22, 1960 Hank MZWaZZeS MM WMM United States Patent 3,193,436 NONWOVEN FABRIC Frank Kalwaites, Somerville, NJ, assignor, by mesne assignments, to Johnson & Johnson, New Brunswick, NJ a corporation of New Jersey Filed July 22, 1960, Ser. No. 44,816 9 Claims. (Cl. 161-59) The present invention is directed to fabrics of exceptional strength comprising a plurality of layers of parallel yarn-like strands of longitudinally aligned, compacted, untwisted fibers in cohesive engagement with one another, the yarn-like strands of adjacent layers lying at an angle to one another and in cohered engagement with one another where the strands cross.

The invention includes the production of these fabrics which are useful as the fabric component of fabric-reinforced plastics and in other similar utilities where fabrics of exceptional capacity to resist tensile loadings are desired, especially when it is desired to employ a fabric capable of assuming the applied tensile load with minimum distortion or elongation. The fabric of this invention is useful, for example, in the apparel trade for both inner wear and outer wear in general, with particular usefulness as interlining or interfacing material. The fabric is also useful as a wiping cloth, towel, handkerchief, and as an industrial fabric; in such uses the strength in the long and the cross directions must be approximately equal and of a high magnitude.

In accordance with the invention, a plurality of highly oriented fiber webs, desirably card webs, having a fiber orientation in a given direction (normally along the longitudinal axis of the web known as the machine direction) of at least 90%, are superposed upon one another with the principal fiber direction of adjacent superposed webs at an angle to one another. The highly oriented fiber Webs are desirably lightly prebonded with a water-sensitive binder to facilitate handling, the webs being preferably superposed by cross-laying as taught, for example, in United States Patent 2,565,647. The superposed webs are then subjected to fluid rearranging forces to cause the fibers in the several individual webs to be shifted to form parallel yarn-like strands of longitudinally aligned fibers bundled together in cohesive contact with one another. The yarnlike strands of adjacent layers cross one another and are deposited into cohesive engagement with one another where they cross.

The fabrics of the invention may include stray fibers and groups of fibers in each of the layers and some of the stray fibers in the various layers may become intermingled by the close proximity of these layers and the fluid rearranging forces which form the crossing strands. However, each layer is constituted essentially by the parallel strands which are formed therein and there is no significant intermingling of the strands of each of the layers with the strands of the other layers.

The invention will be more fully described with reference to the accompanying drawings in which:

FIG. 1 is a fragmentary partially cut-away schematic plan view showing a composite fibrous assemblage of superposed webs in position in an apparatus for forming the fabric of the invention in accordance with the method of the invention;

FIG. 2 is an enlarged fragmentary sectional view taken along the line 2-2 of FIG. 1, and showing the fibers of the composite fibrous assemblage being rearranged to produce the fabric of the invention;

FIG. 3 is an enlarged fragmentary plan view further illustrating the fiber rearrangement shown in FIG. 2, the rearranged fibers being shown in full lines to facilitate understanding;

3,193,436 Patented July 6, 1965 FIG. 4 is a photomicrograph of a fabric produced in accordance with the invention; and

FIG. 5 is a schematic perspective view illustrating the method of the invention in simplified form.

It is essential in accordance with the invention to employ fiber webs in which the degree of fiber orientation is substantially or greater. As a matter of practice, it is preferred to employ highly drafted card webs. Fiber webs having the exceptionally high degree of fiber orientation required by the invention have only recently become available. The production of highly drafted card webs of the type which are employed in accordance with the invention is disclosed in my co-pending applications Serial No. 745,- 010, filed June 27, 1958, now United States Patent 3,135,- 023, and Serial No. 9,969, filed February 19, 1960, now United States Patent 3,119,152, entitled Methods and Apparaus for Doffing andDrafting Fibrous Webs, the disclosures of which are hereby incorporated by reference.

As will be evident, the high proportion of fiber orientation which is required by the invention provides fiber webs which are difficult to handle. Accordingly, it is preferred for ease of handling, to lightly bond the highly oriented card web with a small proportion of a binder which will release the fibers for rearrangement upon the application of fiuid rearranging forces in accordance with the invention. Since the preferred fluid rearranging medium is water, a water-sensitive or water-soluble binder is desirably employed to facilitate handling of the highly oriented fiber webs, polyvinyl alcohol being a preferred watersoluble binder. The polyvinyl alcohol may be applied to the web by spraying, impregnating, print-bonding or in any similar manner.

While the fiber webs are preferably cross-laid as described in United States Patent 2,565,647, any other method or apparatus for cross-laying fabric may be used. Indeed, it is not essential that a cross-laying apparatus be employed so long as the individual highly oriented Webs are superposed with the principal fiber direction in adjacent layers being at an angle to one another.

In accordance with the invention, there may be two, three, or more layers of superposed webs. It is preferred to employ an odd number of webs so that the outer layers may have a common fiber direction. Since continuous production is primarily contemplated, the outer fiber webs desirably have a fiber direction which runs parallel'with the longitudinal axis of the composite product. The intermediate webs desirably have their principal fiber direction at an angle of 30, 45 60 or 90 with respect to the longitudinal axis of the composite product.

Rearrangement of the fibers, in accordance with the invention, is desirably carried out employing any one of the fluid rearranging apparatus and procedures described in Patent 2,862,251 dated December 2, 1958, either one designed to be carried out without the use of vacuum as in FIGS. 7 and 23 of that patent, or one requiring the use of vacuum as an assist in effecting rearrangement of the fibers, as in FIGS. 3134 of that patent. In accordance with one embodiment of the teachings of the patent referred to, the fibrous product to be rearranged is confined between foraminous means and means defining apertures larger than the openings in the foraminous means and a fluid is projected through the apertures against and through the fibrous product and then through the foraminous means. In this way, the fibers of the layer are shifted by the fluid forces and bundled together in restricted areas by these fluid forces and then deposited under conditions of equilibrium which provides yarn-like elements in which the fiber segments are longitudinally aligned in cohesive contact along their lengths. The resulting yarn-like elements or strands are untwisted.

In accordance with the invention, the apertures in the means defining apertures are arranged in straight lines a or rows with the apertures forming straight rows which parallel the principal fiber direction of at least two different principal fiber direct-ions of the superposed Webs. Thus, if there are'three superposed layers inthe cross-laid composite fibrous assemblage to be rearranged, the two outer layers having their principal fiber direction extending along the length of the assemblage and the intermediate layer having its principal fiber direction extending transverse to the longitudinal axis of the assemblage, then the means defining apertures will contain a first series of rows of apertures paralleling the longitudinal axis of the assemblage and these same apertures will also define a second series of rows of apertures extending at a right angle to the first series of rows of apertures. In other words, the means defining apertures will contain apertures arranged in a square pattern. q

Patent 2,862,251 also discloses the use of'a perforated rotary drum or a perforated rotary belt which, in conjunction with an endless foraminous means, enables continuous operation so that the rearranged products may. be supplied indefinitely or lengths thereof woundf into rolls to be supplied'as needed. Since continuous production is primarily contemplated in accordance with the invention, either the perforated rotary drum or perforated rotary belt of said Patent"2,862,251 is desirably employed, either with or without the use of vacuum as disclosed in connection with the various embodiments shown and described in said patent.-

all of the webs are deposited under equilibrium fluid forces and these forces will be greatest where the apertures are closest together. Accordingly, and as diagrammatically shown in FIG. 3, the strands 11' and 12' Referring more particularly to the drawings and particularly'to FIG. 1 thereof, there is shown a composite fibrous assemblage 10 constituted by superposed card Webs 11 and 12, each of which is highly drafted to have a fiber orientation in excess of 90%. As will be seen, the principal fiber directions of the webs 11 and 12 are at an angle to one another, a right angle variation being depicted. The superposed webs 11 and 12 constituting the composite fibrous assemblage 10 are sandwiched between an apertured rearranging plate 13, suitably in the form of an apertured drum as in Patent 2,862,251, and

' foraminous supporting means 14, suitably in the form of identified by line X, and a second series of straight rows of apertures extending longitudinally of plate 13, this direction being identified by line Y. The apertures extending in direction Y form straight rows paralleling the principal fiber direction in Web 11 and the apertures extending in direction X form straight'rows paralleling the principal fiber direction in web 12. Of course, the same apertures 15 form part of rows of apertures extending in other directions.

As shown diagrammatically in F1GS. 2 and 3, the fluid, such as water, steam, air, another liquid or gas or the like, preferably a liquid, is projected as indicated by arrearranged positions and have many not be precisely uniform in size throughout their length. However, with the highly oriented webs which are selected and particularly when longer fibers are selected, stray fibers are at a minimum and the yarn-like strands possess substantially uniform properties along their length. Of particular importance, the fibers are deposited 'in parallel longitudinal alignment in cohesive engagement with one another and fiber undulation is minimized, thus adapting each strand to bear a tensile loading after minimum elongation. 'Moreover, the fibers as deposited are in mechanical equilibrium to provide paralleli'zed and compacted fibers which remain in their no. tendency to return to their original positions. V

The highly'oriented fiber Webs which are superposed to provide the composite fibrous assemblage 10 which is rearranged in accordance with the invention, may comprise any fibrous material, the individual fibrous elements of which are capable of moving under an applied fluid force. Non-fibrous particulate materials and plastic masses may be included in the fiber webs or in the composite fibrous assemblage 10.

The packing of fibers by fluid forces may be eificiently applied to very thin webs or quite thick webs, but particularly satisfactory fabrics may be produced by rearranging composite fibrousassemblagesweighing between about 80 grains/sq. yd., or, slightly lower, and about 1200 grains/ sq. yd, or slightly higher. The'individual card Webs which arestiperimposed desirably weight from 20-250 grains/ sq. yd. and it is preferred toequalize the weight of fiber extending in each of the selected fiber directions to provide fabrics of uniform tensile properties.

The layer of starting material or base web may comprise natural fibers, such as cotton, fiax, wood, silk, wool, jute, asbestos, ramie, rag,-or abaca; mineral fibers such as glass; artificial fibers such as viscose rayon, cupra-ammonium rayon, ethyl cellulose or cellulose acetate; synminor proportion and'should be unbeaten,

rows through the apertures 15 in the plate 13 to pass 5 through the composite fibrous assemblage 10 and the foraminous supporting means 14. V

In the case of a liquid, the streams formed by the projected liquid passing through the apertures 15 and the composite fibrous assemblage 10, strike the foraminous" The fabrics produced in accordance with the invention preferably have an adhesive incorporated therein to strengthenthefabric and reduce any tendency toward disruption thereof during handling: The adhesive may be applied to the composite fibrous product being rearranged with the liquid or other fluid rearranging medium, or it maybe applied directly to the rearranged fabric, as indicated in FIG. 21 of Patent 2,862,251. The adhesive may also be present in the webs 11 and 12 if it is not activated until after rearrangement has been completed, Removal of the water-sensitive preliminary binder is not essential so long as its adhesive character is at least temporarily destroyed to permit fiber rearrangement. The adhesive binding reinforces the cohesive'attraction of the parallel, longitudinally. aligned fibers, but it does not essentially modify the structural arrangement andcohesiveengagernent of fibers which are the underlying causative factors behind the-superior strength properties achieved by the invention.

Any suitableiadhesive may be employed to strengthen the fabrics produced in accordance with the present invention. For instance, water-softenable materials in water solution may be used, these including: beaten cellulose jellies of woodpulp, caroa, ramie, etc.; natural gums including karaya, locust bean, gum arabic and others; starches; and synthetics, such as polyvinyl alcohol, carboxymethylcellulose, polyvinyl acetate, etc. Suitable binders or adhesive materials softenable by solvents other than water, are exemplefied by polyvinyl chloride and polyvinyl butyral and their copolymers. Nonreversible binders may be used if the rearranging occurs before the binders are set; such binders may include urea-formaldehyde and the melamine-formaldehyde condensation products which are in a lower stage of condensation.

Thermoplastic binders may, if desired, be applied to the rearranged web in powder or other particulate form and then fused to bond the fibers, such particulate material including ethyl cellulose, nylon 6, nylon 11, other nylons, polyvinyl chloride, polyvinyl butyral, polyvinyl formal, cellulose acetate, and the like.

The optimum binder content to dimensionally stabilize a given fabric according to the present invention depends upon a number of factors including the nature of the binder material, the size and shape of the binder members and their arrangement in the fabric, the nature and length of the fibers, total fiber weight, and the like. Upwards of about 2 percent, preferably 6-15 percent, of binder based on fiber weight is satisfactory.

A section of the fabric product of the invention is pictured in the enlarged photograph shown in FIG. 4 which shows two card webs having a fiber orientation of about 95% arranged at right angles to one another and rearranged with water in accordance with the invention. The longitudinal alignment and cohesive engagement of the fibers in the yarn-like strands as well as the engagement of strands where they cross and the absence of strand in.

termingling are all self-evident from the photograph. It

will also be observed from the photograph that some of the stray fibers in each layer have been incorporated in the strands of the adjacent layer. Although stray fibers and small groups of consolidated stray fibers are kept to a minimum, the incorporation of these in the strands of an adjacent layer assists in tieing the crossing strands together into a unitary fabric structure and, therefore, a small proportion of stray fibers is not detrimental to the invention.

The sequence of steps employed in the invention is illustrated in FIG. 5. In this figure, a longitudinally oriented card web 11 is continuously supplied, from a source not shown, to the screen belt 14 which is mounted upon rollers 20 and 21 for movement in the direction indicated. Upon the card web 11 is deposited a transversely oriented web 12, the web 12 being formed by any suitable crosslaying apparatus, not shown. The superimposed webs which constitute the composite fibrous assemblage 10 are then moved beneath the apertured belt 13 which is mounted upon rollers 22 and 23 for movement as indicated, the composite fibrous assemblage 10 being sandwiched between the apertured belt 13 and the screen belt 14. Water is then projected through the sandwich as indicated at 24 and the rearranged fabric constituted by strands 11' and 12 is delivered from between rollers 21 and 23 for drying and storage.

Referring more particularly to the fiber rearranging process which is employed, the foraminous support may be for-med of any suitable material, a screen belt in woven form being preferred. Using an apertured means having uniform apertures of about of an inch in diameter, effective fiber rearrangement may be obtained using a foraminous support having from about .1500 openings to about 50,000 openings per square inch or more, preferably about 10,000 openings to 40,000 openings per square inch.

The invention is illustrated in the following examples:

Example 1 Three highly drafted card webs having a fiber orient-ation in the machine direction of about and composed of viscose, 2 inch, 1 /2 denier fibers are provided, two of the webs weighing 75 grains/sq. yd. each, and the third web weighing 150 grains/sq. yd. All three webs are lightly spray-bonded with a 5% by weight solution of polyvinyl alcohol in water and dried. A composite fibrous assemblage is formed by placing the first 75 grain web longitudinally upon a supporting screen belt, sections of'the 150 grain web are laid transversely across the first web and the second 75 grain web is laid longitudinally on top of the 150 grain web to form a three-ply composite assemblage in which the fibers in the outer layers run in the same direction. This threeply composite is then passed to the apparatus illustrated in FIGS. 7-10 of Patent 2,862,251, for confinement between the apertured drum and the foraminous belt thereof. The apertured drum is formed to have a thickness of A of an inch with 324 apertures per square inch arranged in a square pattern, each aperture being round with a diameter of inch. The fior-aminous supporting belt is a woven, stainless steel screen of 200 mesh (substantially 40,000 openings per square inch).

Water is projected through the apertures in the drum and thence through the superposed car-d webs and the foraminous belt backing screen by nozzles arranged radially inside the drum. The nozzles are solid cone nozzles in overlapping relation and deliver 1.3 gallons of water per minute under a pressure of 90-100 pounds per square inch. The drum is driven at 50 feet per minute and the water leaving the nozzles has a velocity of approximately feet per second.

Example II Example I is repeated with the exception that the wet rearranged fabric, prior to drying, is pattern-bonded in a design of 6 horizontal wavy lines per inch with polyvinyl chloride resin applied from a dispersion containing 50% by weight of dispersed resin particles. In this manner, about 70 grains of binder is added per square yard of fabric to provide a binder-reinforced product having improved resistance to mechanical disruption and having a total weight of 370 grains per square yard.

The invention is defined in the claims which follow.

I claim:

1. A fabric comprising a plurality of layers each consisting essentially of parallel, untwisted yarn-like strands of parallel longitudinally aligned compacted textile fibers of about A inch to about 2 inches in length in cohesive contact with one another along their lengths and in mechanical equilibrium, the strands of adjacent layers lying at an angle to one another and being bonded with one another where the strands cross.

2. A fabric as recited in claim 1 in which each of said layers include a small proportion of stray fibers incorporated in the strands of an adjacent layer.

3. A fabric as recited in claim 1 in which there is essentially no intermingling of the strands of each of the layers with the strands of the other layers.

4. A fabric as recited in claim 1 in which said fabric includes at least three layers, the strands forming the outer layers of said fabric running in the same direction.

5. A fabric as recited in claim 1 in which said yarnlike strands possess substantially uniform characteristics along the length thereof.

6. A fabric as recited in claim 1 in which said fabric includes an odd number of layers, there being at least three such layers, and in which the strands in the outer 'layers run in the same direction.

7. A fabric comprising a plurality of layers each consisting essentially of parallel, untWi-sted yarn-like strands of parallel longitudinally aligned compacted textile fibers of about inch to about 2 inches in length in cohesive engagement with one another, along their lengths and in mechanical equilibrium, the strands of adjacent layers lying at an angle of 90 to one another and being bonded with one another where the strands cross.

7 i t s 8. A fabric comprising a plurality of layers each conthree such layers, and in which the strandsin the outer sisting essentially of parallel, untwisted yarn-like strands layers WI! 111 ther'same ec on.

of parallel longitudinally aligned compacted textile fibers R of about inch to about 2 inches in length in cohesiye eferences Cited by the Exammer engagement with one another, along their lengths and in 5 V UNITED S EN mechanical'equilib'rium, the strands of adjacent layers 7 ,9 10/34 Bfewstfil ----jlying at an angle of 3090 tov one another and being, 2266 761 7 12/41 F at l15446 bonded with one another Where the strands cross. 7/58 i154 46 9 A fabric as recited in claim 8in which said fabric 712/58 Kalwaltes 161.409 10 2,900,980 8/59 H ElIW OOd 161-157 incudes an odd number of layers, there being at last r 1 EARL M. BERGERT, Primary Exam'z'ner.

Claims (1)

1. A FABRIC COMPRISING A PLURALITY OF AYERS EACH CONSISTING ESSENTIALLY OF PARALLEL, UNTWISTED YARN-LIKE STRANDS OF PARALLEL LONGITUDINALLY ALIGNED COMPACTED TEXTILE FIBERS OF ABOUT 1/4 INCH TO ABOUT 2 INCHES IN LENGTH IN COHESIVE CONTACT WITH ONE ANOTHER ALONG THEIR LENGTHS AND IN MECHANICAL EQUILIBRIUM, THE STRANDS OF ADJACENT LAYERS LYING AT AN ANGLE TO ONE ANOTHER AND BEING BONDED WITH ONE ANOTHER WHERE THE STRANDS CROSS.

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