Method And Apparatus (continuous Imperforate Portions On Backing Means Of Closed Sandwich)

Abstract

Method and apparatus for producing nonwoven fabrics that contain holes or other areas of low fiber density and have a plurality of patterns of groups of fiber segments that alternate and extend throughout the fabric. The method and apparatus include the steps of positioning the starting web between an apertured forming means and a backing means that has continuous imperforate portions that lie between and interconnect discontinuous foraminous portions, then directing fluid rearranging forces through the apertures of the forming means against the fibers of the starting web, causing some of the fluid streams to strike continuous imperforate portions of the backing means and all of the fluid streams ultimately to pass through the foraminous portions of the backing means.

Parent Case Text

This is a continuation-in-part application of my co-pending application Ser. No. 22,309, filed Mar. 24, 1970 now abandoned.

Description

This invention relates to a method and apparatus for the production of nonwoven fabrics, and more particularly to a method and apparatus for the production of non-woven fabrics from a layer of fibrous material such as a fibrous web in which the individual fiber elements are capable of movement under the influence of applied fluid forces, to form a fabric that contains apertures or holes, or other areas of low fiber density, and has a plurality of patterns of groups of fiber segments that alternate and extend throughout the fabric.

BACKGROUND OF THE INVENTION

Various methods and apparatus for manufacturing apertured nonwoven fabrics involving the rearrangement of fibers in a starting layer of fibrous material have been known for a number of years. Some of the methods and apparatus for the manufacture of such fabrics are shown and described in U.S. Pat. No. 2,862,251, which discloses the basic method and apparatus of which the present invention is a specific form, and in U.S. Pat. Nos. 3,081,500, 3,025,585 and 3,033,721.

The nonwoven fabrics made by the methods and apparatus disclosed in those patents contain apertures or holes, or other areas of low fiber density, often outlined by interconnected yarn-like bundles of closely associated and substantially parallel fiber segments. (The term "areas of low fiber density" is used in this specification and claims to include both (1) areas in which relatively few fibers are found in comparison to the rest of the fabric, and (2) apertures (holes) that are substantially or entirely free of fibers.)

One of the specific methods for producing rearranged nonwoven fabrics that is disclosed in U.S. Pat. No. 2,862,251 is to support a loose fibrous web or layer between an apertured forming member and a permeable backing member, and then direct streams of rearranging fluid through the apertures of the former member in order to apply spaced sets of opposing fluid forces to the layer. The spaced streams of fluid pass through the fibrous layer and over and through the backing member, to pack groups of fiber segments into closer proximity and substantial parallelism in interconnected yarn-like bundles of fiber segments that define holes or other areas of low fiber density corresponding to the pattern of the apertures in the apertured forming means.

Another known method for producing rearranged nonwoven fabrics is to support a loose fibrous web or layer upon solid backing means with spaced apertures distributed throughout the area thereof, and direct streams of rearranging fluid against the fibrous starting layer so that the fluid passes through that layer and then out through the spaced apertures in the backing means. The result of this method is to form a nub of interentangled, tightly packed, helter-skelter fiber segments in each aperture of the backing means, and to position other fiber segments in flat, ribbon-like groups of substantially aligned fiber segments between pairs of immediately adjacent nubs to interconnect the same.

In the first method just described, the streams of rearranging fluid enter the fiber rearranging zone at spaced locations determined by the position of the apertures in the apertured forming means against which the fluid streams are first directed. Then, when the rearranging fluid leaves the rearranging zone, it does so through foramina uniformly dispersed throughout the permeable backing member.

Exactly the contrary is true with the second method just described. In that method, the streams of rearranging fluid are dispersed uniformly across the layer of fibrous starting material as they are directed against that layer upon entering the rearranging zone, and leave the rearranging zone at spaced locations determined by the position of the apertures in the apertured backing means.

Another significant feature of the second method is that streams of rearranging fluid initially dispersed uniformly across the fibrous starting layer are consolidated into spaced streams confined by the walls of the apertures in the apertured backing means as they pass out of and away from the fiber rearranging zone. It is this consolidation of the streams of fluid that creates the turbulence that in turn packs the nubs in the nonwoven fabric of this prior art method into tightly compacted, interentangled fiber accumulations, with the individual fibers thereof having entirely random orientation.

SUMMARY OF INVENTION

I have now discovered that, unexpectedly, one can combine these two different prior art methods of producing rearranged nonwoven fabrics, and achieve very satisfactory rearrangement of the fibers of the fibrous starting material into a fabric having a plurality of patterns of groups of fiber segments that alternate and extend throughout the fabric.

In the method of this invention, the starting material is a layer of fibrous material whose individual fibers are in mechanical engagement with one another but are capable of movement under applied fluid forces. The layer of fibrous starting material is supported in a fiber rearranging zone in which fiber movement in directions parallel to the plane of said fibrous material is permitted in response to applied fluid forces. Streams of rearranging fluid, preferably water, are projected into the fibrous layer at entry zones spaced from each other adjacent one surface of the layer. For ease of visual resolution of the patterns on the resulting fabric, each of the entry zones has a width at its narrowest part equal to at least about ten times, and preferably about twenty or more times, the average diameter of the fibers of the fibrous starting material. These streams of rearranging fluid are passed through the layer of fibrous starting material as it lies in the rearranging zone, to effect movement of at least some segments of the fibers transverse to the direction of travel of the projected streams.

In the next step of the method, the passage of first portions of the rearranging fluid out of the fibrous layer is blocked at continuous barrier zones located adjacent the opposite surface of the fibrous layer, and, at the same time, those portions of fluid are deflected sidewise towards the other portions of the rearranging fluid and are actively mingled with the latter. For ease of visual resolution of the various fiber patterns in the fabric resulting from use of this invention, each of the barrier zones has a width at its narrowest part equal to at least about the width of one of the entry zones at its narrowest part. All the portions of intermingled rearranging fluid are then passed out of the rearranging zone through spaced, discontinuous, foraminous major fiber accumulating zones defined by the continuous barrier zones and each having an area at least about three times, and preferably about four or more times, the area of one of the entry zones.

The passage of the rearranging fluid through the layer of fibrous starting material as just described moves some of the fiber segments that are in registry with the continuous barrier zone into the major fiber accumulating zones, and positions those fiber segments with other fiber segments in at least one yarn-like bundle of closely associated and substantially parallel fiber segments in each major fiber accumulating zone in a location therein complementary to the entry zones. In addition, the rearranging fluid moves other fiber segments that are in registry with the barrier zones into substantial alignment in bridging positions extending between the discontinuous major fiber accumulating zones.

The result of this fiber rearrangement is a nonwoven fabric having a first pattern of groups of fiber segments in discontinuous portions of the fabric corresponding to the pattern of the major fiber accumulating zones, each of the discontinuous portions of the fabric in this first pattern including at least one yarn-like bundle of closely associated and substantially parallel fiber segments. The fabric also includes a second pattern of groups of substantially aligned fibers extending between pairs of discontinuous portions of the fabric immediately adjacent each other in the first pattern. In some form of the invention, as explained below, third and fourth patterns of groups of fiber segments are also present.

In one form of the method and apparatus of this invention, the fibrous starting layer is supported on a backing means that is imperforate except for spaced foraminous portions arranged in a discontinuous pattern, and an apertured forming means is positioned above the fibrous layer to provide a zone in which fiber movement in directions parallel to the backing means can occur in response to applied fluid forces. The width of each forming aperture at its narrowest part is equal to at least about ten times, and preferably about twenty or more times, the average diameter of the fibers of the fibrous starting material. The area of each of the foraminous portions of the backing means is at least about three times, and preferably about four of more times, the area of an aperture of the apertured forming means. The imperforate portions of the backing means lie between and interconnect the discontinuous foraminous portions.

With a layer of fibrous starting material positioned between the elements just described, streams of rearranging fluid, preferably water, are projected through the apertures of the apertured forming means, against the layer of fibrous starting maerial; against the continuous imperforate portions of the backing means, and out through the discontinuous foraminous portions of the backing means. At the discontinuous foraminous portions of the backing means, the portions of the rearranging fluid that have struck the imperforate portions of the backing means, and have been deflected thereby, are actively mingled with othe portions of rearranging fluid.

Under the forces applied by these streams of fluid, some of the fiber segments that are in registry with the continuous imperforate portions of the backing means are moved into areas of the fibrous layer overlying the foraminous portions of the backing means, to form groups of fiber segments there that include at least one yarn-like bundle of closely associated and substantially parallel fiber segments in each such area, while other fiber segments in registry with the continuous imperforate portions of the backing means are moved into substantial alignment in positions bridging those imperforate portions. In addition, when desired, fiber segments that are in registry with the apertures of the apertured forming means and also with the foraminous portions of the backing means may be moved by the rearranging fluid into surrounding areas of the fibrous layer, where they are positioned in yarn-like bundles of closely associated and substantially parallel fiber segments, to define holes or other areas of low fiber density.

The action of the rearranging fluid just described produces a nonwoven fabric having two or three fiber patterns, all of which alternate and extend throughout the fabric. The first pattern is a pattern of groups of fiber segments arranged in accordance with the pattern of arrangement of the discontinuous foraminous portions of the backing means, each such group containing at least one yarn-like bundle of fiber segments. The second is a pattern of groups of substantially aligned fiber segments interconnecting the portions of the fabric in the first pattern; this pattern corresponds to the configuration of the continuous imperforate portions of the backing means, and these groups of aligned, bridging fiber segments may take the form of flat ribbon-like groups, yarn-like bundles, or a latticework of yarn-like bundles. The third pattern, when it is present, is an elaboration of bundles within the first pattern, and is a pattern of yarn-like bundles of closely associated and substantially parallel fiber segments, arranged in accordance with the land areas of the apertured forming means, that may define a pattern of holes or other areas of low fiber density.

An interesting result is obtained with this invention when the starting layer of fibrous material is not too heave in weight and the foraminous portions of the backing means have a plurality of protuberances and troughs alternating across their surfaces in both the longitudinal and transverse directions. The resulting fabric displays a fourth pattern extending throughout the fabric, in addition to the three fiber patterns already described. This fourth pattern, which is disposed within the third pattern described, is a pattern of yarn-like bundles of closely associated and substantially parallel fiber segments arranged according to the pattern of the troughs on the backing means, and lying within the holes or other areas of low fiber density in the third pattern.

The interaction of the different types of rearranging forces in the two prior art methods that have been described above would be expected to produce highly undesirable results. In the present invention, the streams of rearranging fluid entering the fiber rearranging zone at spaced locations such as the apertures of an apertured forming means (i.e., spaced entry zones) produce yarn-like bundles of fiber segments in the areas of the fibrous starting material in either or both of two locations, depending upon a number of reaction conditions -- above the discontinuous foraminous portions of the backing means (i.e., fiber accumulating zones) and above the continuous interconnecting imperforate portions of the backing means (i.e., barrier zones). In either case, undesirable results would be expected to be produced.

In the first case, since the individual foraminous portions of the backing means are at least about three times as large in area as an individual aperture of the apertured forming means, the bundling effect of fluid streams from a plurality of separate forming apertures is exerted within a single foraminous area, in which at the same time those very streams are being intermingled for passage through the backing means. In this situation, the turbulence in and above the foraminous portions of the backing means, as the various streams of rearranging fluid are consolidated into a single confined stream so as to move out of the rearranging zone, would be expected to destroy completely any tendency towards producing discrete yarn-like bundles of closely associated and substantially parallel fiber segments within the areas overlying the foraminous portions of the backing means.

In the second case, the streams of rearranging fluid that enter the fiber rearranging zone at spaced locations above the continuous imperforate portions of the backing means tend to produce yarn-like bundles of fiber segments to bridge those imperforate portions. Now the turbulence in the areas of the fibrous web above the foraminous portions of the backing means works against this bundling effect not only by tending to prevent the formation of any discrete yarn-like bundles above the foraminous portions (as just described), but by opposing the formation of bundles over the imperforate portions of the backing means as well. For the action of the fluid forces in an area of turbulence not only tends to interentangle and consolidate the fiber segments as they extend into the web areas on either side of the imperforate portions of the backing means which they bridge, but also tends to pull the fiber segments taut and spread them out in a flat array over the imperforate land areas of the backing means, and both these tendencies oppose separation of the fiber segments into discrete closely packed yarn-like bundles to bridge the land areas of the backing means. This latter effect is magnified by the fact that the fluid forces exerted in an area of turbulence such as just referred to are markedly greater than the bundling forces applied within an aperture of the apertured forming means, since the area of each foraminous portion of the backing means is at least about three times as large as the area of each of the apertures.

Surprisingly, it has been found that the turbulence of the rearranging fluid as it passes through the foraminous portions of the backing means does not produce any of the undesirable results just described, either in the areas of the fibrous web above those foraminous portions or in the areas above the imperforate portions therebetween. On the contrary, the method and apparatus of this invention successfully combine the two types of fluid rearranging forces to bring about satisfactory fiber rearrangement of two or more dissimilar types, and thus produce an attractive nonwoven fabric having a plurality of patterns, each of which patterns alternates and extends throughout the fabric.

FURTHER DESCRIPTION OF INVENTION

The basic method and apparatus of this invention are shown and described fully in my U.S. Pat. No. 2,862,251, issued Dec. 2, 1958. Full particulars of the basic in-vention as disclosed in that patent are incorporated in this application by reference, although some of those particulars are repeated here. In addition, the specific feature peculiar to the method and apparatus of the present invention -- which is the use of a fiber rearranging zone having spaced entry zones (for example, the apertures of an apertured forming means) on one side, and continuous barrier zones and discontinuous, foraminous fiber accumulating zones on the other side (for example, a backing means that is imperforate except for discontinuous foraminous portions), each entry zone having a width at its narrowest part equal to at least a specified number of times the average diameter of the fibers in the fibrous starting material, and each fiber accumulating zone having an area at least a specified number of times larger than the area of an entry zone -- is described in detail in this application.

Starting Material

The starting material used with the method or apparatus of this invention may be any of the standard fibrous webs such as oriented card webs, isowebs, air-laid webs, or webs formed by liquid deposition. The webs may be formed in a single layer, or by laminating a plurality of the webs together. The fibers in the web may be arranged in a random manner of may be more or less oriented as in a card web. The individual fibers may be relatively straight or slightly bent. The fibers intersect at various angles to one another such that, generally speaking, the adjacent fibers come into contact only at the points where they cross. The fibers are capable of movement under forces applied by fluids such as water, air, etc.

To produce a fabric having the characteristic hand and drape of a textile fabric, the layer of starting material used with the method or apparatus of this invention may comprise natural fibers such as cotton, flax, etc.; mineral fibers such as glass; artificial fibers such as viscose rayon, cellulose acetate, etc.; or synthetic fibers such as the polyamides, the polyesters, the acrylics, the polyolefins, etc., alone or in combination with one another. The fibers used are those commonly considered textile fibers; that is generally having a length from about 1/4 inch to about 2 to 21/2 inches. Satisfactory products may be produced in accordance with this invention from starting webs weighing between 80 grains per square yard to 1200 grains per square yard or somewhat higher.

Apertures Forming Means

In one form of the method of this invention, and in the apparatus of this invention, the fluid entry zones into the fiber rearranging zone are defined by an apertured forming means.

The apertured forming means used with the method and apparatus of this invention is solid throughout its area except for the forming apertures disposed longitudinally and transversely across the member. The forming apertures may have any desired shape, i.e., round, square, diamond, oblong, free form, etc.

The width at the narrowest part of each of the apertures of the apertured forming means must be large enough that streams of rearranging fluid passing through those apertures will be effective to separate groups of fiber segments into yarn-like bundles spaced sufficiently far apart to permit reliable visual resolution. Without such resolution, any bundle of fiber segments produced would seem to the person viewing the fabric to fuse or merge together with other such bundles, with the result that no clear pattern would be apparent in the fabric. To achieve such resolution, the width of each aperture at its narrowest part should be equal to at least about ten times, and preferably at least about twenty times, the average diameter of the fibers in the fibrous starting material; i.e., at least 0.015 inch and preferable 0.020 inch.

The maximum dimensions of each aperture of the apertured forming means are limited by the requirement mentioned below as to the ratio between the areas of the forming apertures and the foraminous portions of the backing means.

The land areas of the apertured forming means that lie between and interconnect the forming apertures may be either narrow or broad in comparison to the forming apertures, as desired. Generally speaking, the narrower the land areas are, the more tightly compacted will be the yarn-like bundles of closely associated and substantially parallel fiber segments that are formed beneath those land areas.

Backing Means Having Discontinuous Foraminous Portions

As already indicated, in one form of this invention the fibrous starting layer is supported on backing means having foraminous portions arranged in a discontinuous pattern, and continuous imperforate portions that lie between and interconnect the discontinuous foraminous portions to provide barrier zones against the passage or rearranging fluid out of the fiber rearranging zone. For ease of visual resolution of the different fiber patterns of the nonwoven fabric made by the practice of this invention, the width of each imperforate portion of the backing means at its narrowest part is equal to at least about the width of the narrowest part of the aperture of the apertured forming means with which the backing means is used. The foramina of the foraminous portion of the backing means are substantially smaller than the apertures of the apertured forming means.

The bridging of the imperforate portions of the backing means by aligned fiber segments referred to above that is produced by the practice of this invention is brought about by three factors -- good drainage of the rearranging fluid from the fiber rearranging zone with no uncontrolled washing away of fibers, the accumulation and retention of groups of fiber segments at spaced points across the backing means, and the pulling taut of other fiber segments that extend between such groups and are anchored by them at a plurality of points along their lengths.

Good drainage is achieved by avoiding the use of too much rearranging fluid and by employing discontinuous foraminous portions in the backing means that are large enough and not too widely spaced. As indicated above, the area of each of the discontinuous foraminous portions of the backing means should be at least about three times, and preferably four times, the area of an aperture of the apertured forming means. These foraminous portions should be closely enough spaced to each other that they occupy together at least about 20 per cent, and preferably about 30 per cent or even more, of the total area of the backing means.

Accumulation and retention of fiber segments at spaced points across the backing means takes place when each foraminous portion of the backing means is large enough that a group of fibers can be accumulated and retained there, whether in the form of a group of fiber segments including only a single yarn-like bundle or a plurality of yarn-like bundles of fiber segments. This condition is automatically met in the present invention by the restrictions on the minimum dimension of each aperture of the apertured forming means (i.e., an entry zone) in comparison to the average fiber diameter, and on the relative area of each foraminous portion of the backing means (i.e., a fiber accumulating zone) in comparison to the area of a forming aperture. There is no practical limit other than esthetic requirements on the maximum area of each foraminous portion of the backing means.

The pulling taut of fiber segments between adjacent groups in which they are anchored is achieved by limiting the maximum spacing of the foraminous portions of the backing means. To establish two reliable anchor points for each individual fiber segment, the foraminous portions of the backing means should be spaced from other such portions immediately adjacent thereto by no more than about 1/3 the average length of the fibers being rearranged, and preferably no more than about 1/5 or 1/6 the length of the fibers. In general, this means that with 11/2 inches staple length fibers, each pair of foraminous portions of the backing means should be spaced, at their closest points, no more than about 1/2 inch arart, and preferably no more than about 1/4 inch.

When the spacing referred to is about one to two times thw width, at its narrowest part, of an aperture of the apertured forming means, the aligned fiber segments may take the form of yarn-like bundles extending between the areas of the fabric lying above adjacent foraminous portions of the backing means. When the spacing in question is about three or more times the width of a forming aperture at its narrowest part, the aligned fiber segments ordinarily take the form of flat, ribbon-like groups of segments.

In plan view, the discontinuous foraminous portions of the backing means may have any shape desired, i.e., circular, oval, diamond, square, etc.

The discontinuous foraminous portions may be flush with the imperforate portions of the backing means, or at a different elevation. If a three-dimensional effect is desired for the fiber grouping accumulated at each foraminous portion of the backing means, the continuous imperforate portions of the backing means should lie above the foraminous portions by at least about 1/32 inch, or as much as 1/16 inch if desired. This difference in height must not be too great, however, if a pattern of yarn-like bundles of fiber segments (produced either by the apertures of the apertured forming means or by protuberances on the discontinuous foraminous portions of the backing means) is also desired.

Generally speaking, with a foraminous portion at a lower elevation, the larger the area of the foraminous portion, the more pronounced will be the three-dimensional effect in the resulting fabric. The three-dimensional effect also increases with increased flexibility in the fibers being arranged, since the more flexible a fiber is, the more easily it can conform to the lower elevation of the foraminous portions of the backing means.

As already indicated above, when a fourth pattern of areas of low fiber density is desired in the fabric produced by use of the backing means already described in the method or apparatus of this invention, the discontinuous foraminous portions of the backing means are provided with a plurality of protuberances and troughs alternating across their surface in both the longitudinal and transverse directions. As illustrated in the drawings below, the tops of the protuberances rise above the bottoms of the immediately adjacent troughs by a vertical distance equal to at least about three times the average diameter of the fibers in the layer of fibrous starting material or about 0.005 inch. Preferably, the distance should be equal to about ten times the average diameter of those fibers. The protuberances should not rise so far above their immediately adjacent troughs as to disrupt formation of any pattern of areas of low fiber density present that corresponds to the apertures of the apertured forming means. The top of each protuberance is spaced from the tops of the immediately adjacent protuberances by a horizontal distance equal to at least about 30 times the average diameter of the fibers of said fibrous starting material.

During use of the method or apparatus of this invention, the apertured forming means and the backing means are spaced from each other to provide a fiber rearranging zone in which fiber movement in directions parallel to the backing means is permitted in response to applied fluid forces.

Rearranging Fluid

The rearranging fluid for use with this invention is preferably water of a similar liquid, but it may be other fluids such as a gas, as described in my U.S. Pat. No. 2,862,251.

If desired, a vacuum may be applied at the exit side of the fiber rearranging zone of this invention, to assist in moving the rearranging fluid through the fibrous starting material and in rearranging the fibers of the material into a patterned nonwoven fabric. This feature is most useful when the rearranging fluid is a liquid.

BRIED DESCRIPTION OF THE DRAWINGS

The invention will be more fully described in connection with the accompanying drawings, in which:

FIG. 1 is a diagrammatic showing in elevation of one type of apparatus that can be employed in the present invention.

FIG. 2 is an enlarged diagrammatic plan view of a portion of a backing means that can be used in the apparatus of FIG. 1.

FIG. 3 is a cross sectional view taken along the line 3--3 of FIG. 2.

FIG. 4 is a further enlarged diagrammatic plan view of the element shown in FIG. 2, with the apertures of the apertured forming means used in conjunction therewith shown in dashed lines.

FIG. 5 is an enlarged fragmentary diagrammatic plan view of the foraminous portion of another backing means that can be used with the apparatus of FIG. 1, an aperture of the apertured forming means being shown in dashed lines.

FIG. 6 is a cross sectional view taken along the line 6--6 of FIG. 5.

FIG. 7 is a cross sectional view taken along line 7--7 of FIGS. 5 and 6.

FIGS. 8 is a photomicrograph of a nonwoven fabric made in accordance with the present invention, shown at an original enlargement of five times.

FIG. 9 is a photomicrograph of another non-woven fabric made in accordance with the present invention, shown at an original enlargement of five times.

FIG. 10 is an enlarged diagrammatic plan view of a portion of another backing means.

FIG. 11 is a cross sectional view taken along the line 11--11 of FIG. 10.

FIG. 12 is a photomicrograph of another non-woven fabric made in accordance with the present invention, shown at an original enlargement of five times.

FIG. 13 is a photomicrograph of the fabric of FIG. 12 from the opposite side, showing a different but similar portion of the fabric, at an original enlargement of five times.

FIG. 14 is a photomicrograph of another nonwoven fabric made in accordance with the present invention, shown at an original enlargement of five times.

FIG. 15 is a photomicrograph of the fabric of FIG. 14 from the opposite side, showing a different portion of the fabric, at an original enlargement of five times.

FIG. 16 is an enlarged diagrammatic plan view of a portion of another backing means.

FIG. 17 is a cross sectional view taken along the line 17--17 of FIG. 16.

FIG. 18 is a photomicrograph of another nonwoven fabric made in accordance with the present invention, shown at an original enlargement of five times.

FIG. 19 is a photomicrograph of the fabric of FIG. 18 from the opposite side, showing a similar portion of the fabric, at an original enlargement of five times.

FIG. 20 is a photomicrograph of another non-woven fabric made in accordance with the present invention, shown at an original enlargement of five times.

FIG. 21 is a photomicrograph of the fabric of FIG. 20 from the opposite side, showing the same portion of the fabric, at an original enlargement of five times.

FIG. 22 is a schematic drawing that represents a portion of the nonwoven fabric of FIGS. 20 and 21.

FIG. 23 is a schematic drawing that represents a further portion of the same nonwoven fabric.

FIG. 24 is an enlarged diagrammatic showing of another fabric made in accordance with this invention.

DETAILED DESCRIPTION OF SPECIFIC FORMS OF THE INVENTION

FIG. 1 shows one form of apparatus that may be used in accordance with the present invention. Full particulars of the basic apparatus of which this apparatus is a specific form, including methods of mounting, rotation, etc., are described in U.S. Pat. No. 2,862,251 issued Dec. 2, 1958, and are incorporated in the present application by reference and thus need not be described in complete detail here. In view of this reference, the apparatus of FIG. 1 will be described in general terms insofar as its essential elements are the same as in the patent just mentioned, and as already explained above, the novel feature used to manufacture non-woven fabrics in accordance with the present invention will be described in more detail.

The apparatus of FIG. 1 includes a rotatable backing drum 15 suitably mounted on flanged guide wheels 17 and 18, which are mounted for rotation on shafts 25 and 26. The drum has foraminous portions 19 uniformly spaced over its entire surface, with the remaining portions of the drum that lie between and interconnect the foraminous portions constituting imperforate land areas 20.

Backing drum 15, as shown in FIG. 2, has a discontinuous pattern of foraminous portions 19 and a continuous pattern of imperforate portions 20 lying between and interconnecting them. In FIG. 2, the foraminous portions are round and arranged such that four of them lie in a square pattern over the surface of drum 15. As already indicated above, the foraminous portions of the backing member may have any shape desired. They may also be arranged in any discontinuous pattern over the backing member; i.e., they may be aligned longitudinally and/or transversely, staggered, etc.

FIG. 3 shows a cross section of the backing means of FIG. 2. As seen each continuous imperforate portion 20 of backing means 15 has a curved top surface that rises slightly above the top surface of foraminous portions 19 of the backing means. Because of the curved top surface, central portion 21 rises above edge portions 22 of imperforate portion 20 of the backing means. Extreme edge portions 23 are slightly rounded.

Outside the drum, a stationary manifold 27 to which a fluid is supplied through conduit 28 extends along the full width of the drum. On one side of the manifold is a series of nozzles 29 for directing the fluid toward the drum.

About the greater portion of the periphery of the drum there is positioned an apertured forming belt 30. Forming belt 30 is solid throughout its area except for forming apertures 31 disposed across its surface. As already indicated above, these forming apertures may have any shape desired. They may also be arranged in any discontinuous pattern over the support member; i.e., they may be aligned longitudinally and/or transversely staggered, etc., with continuous land areas 32 between them. In the apparatus of FIG. 1, forming apertures 31 are circular in shape and are arranged such that four of them lie in a square pattern over the surface of forming belt 30.

The diameter of circular apertures 31 is at least about ten times the average diameter of the fibers in the fibrous starting material. With fibers of 1 1/2 denier, for example, the diameter of apertures 31 is 0.015 inch or larger.

Forming belt 30 passes about drum 15 and separates from the drum at guide roll 33, which rotates on shaft 34. The belt passes downwardly around guide roll 35, rotating on shaft 36, and then rearwardly over vertically adjustable tensioning and tracking guide roll 37 rotating on shaft 38, and then around guide roll 39 on shaft 40. The member passes upwardly and around guide roll 41 rotating on shaft 42, to be returned about the periphery of the drum.

Backing drum 15 and apertured forming belt 30 provide a rearranging zone between them through which a fibrous starting material may move to be rearranged, under the influence of applied fluid forces, into a nonwoven fabric having a plurality of patterns of fiber segments that extend throughout its area.

Tension on forming belt 30 is controlled and adjusted by the tensioning and tracking guide roll. The guide rolls are positioned in slideable brackets which are adjustable to assist in the maintenance of the proper tension of the belt. The tension required will depend upon the weight of the fibrous web being treated and the amount of rearrangement and patterning desired in the final product.

Backing drum 15 rotates in the direction of the arrow shown, and apertured forming belt 30 moves in the same direction at the same peripheral linear speed and within the indicated guide channels, so that both longitudinal and lateral translatory motion of the backing means, the apertured forming means, and the fibrous layer with respect to each other are avoided. The fibrous material 43 to be treated is fed between the backing drum and apertured forming member 30 at point "A," passes through a fiber rearranging zone where fluid rearranging forces are applied to it, and is removed in its new, rearranged form as nonwoven fabric 44 between the backing drum and apertured forming belt at point "B."

As fibrous material 43 passes through the fiber rearranging zone, a liquid such as water is directed against the outer surface of apertured forming belt 30 by nozzles 29 mounted outside the drum, the water passes through apertures 31 of forming means 30 into the layer of fibrous starting material 43 to produce rearrangement of the fibers of the web, and the water thence passes through foraminous portions 19 of backing drum 15.

Vacuum assist box 45 is located inside rotating drum 15 opposite manifold 27 and nozzles 29. Vacuum box 45 has a slotted surface located closely adjacent the inner cylindrical surface of drum 15, and through which suction is caused to act upon the web. Suction thus applied assists in the rearrangement of the fibers as the web material passes through the rearrangign zone. In addition, it serves to help dewater the web and prevent flooding during fiber rearrangement. A drain pan 46 is provided in order that water deflected by the outside of apertured forming belt 30 will be carried away from the machine.

In the apparatus of FIG. 1, the relative positioning of rotatable backing drum 15 and apertured forming means 30 with respect to the fibrous layer 43 being rearranged is maintained through the rearranging zone as explained above by guarding against either longitudinal or lateral translatory movement. This maintains the integrity of the rearranged fabric as it is subjected to fluid forces from the rearranging liquid.

FIG. 4 is a still further enlarged diagrammatic view of a portion of backing means 15 used in the apparatus of FIG. 1. Discontinuous foraminous portions 19 are circular in shape and are arranged in a square pattern over the surface of the backing member. The remainder of the backing member is comprised of continuous imperforate portions 20. Circular forming apertures 31 of apertured forming means 30, also arranged in a square pattern, are shown in dashed lines. During use of the apparatus of FIG. 1, apertured forming means 30 and backing means 15 are spaced from each other to provide a fiber rearranging zone.

The directions the streams of rearranging fluid projected through apertures 31 of apertured forming means 30 take as they move into and through the fibrous web determine the type of forces applied to the fibers and in turn, the extent of rearrangement of the fibers. Since the directions the streams of rearranging fluid take after they pass through apertures 31 are determined by foraminous portions 19 and imperforate portions 20 of support member or backing means 15, it follows that the patterns of these portions of the backing means help determine the patterns of fiber arrangement, as well as the patterns of holes or other areas of low fiber density, in the resultant fabric.

When backing means 15 and apertured forming means 30 are employed in the method or apparatus of this invention as shown in FIG. 4, streams of rearranging fluid passing through forming apertures 31 cause some of the fiber segments that are in registry with continuous imperforate portions 20 of backing means 15 to move into areas of fibrous layer 43 overlying foraminous portions 19 of the backing means, to form groups of fiber segments there that include at least one yarn-like bundle of closely associated and substantially parallel fiber segments in each such area. At the same time, the streams of rearranging fluid move other fiber segments that are in registry with imperforate portions 20 into substantial alignment in positions bridging the continuous imperforate portions of the backing means from one discontinuous foraminous area 19 to another.

This fiber rearrangement produces a first pattern of fiber segmens arranged in accordance with the pattern of arrangement of foraminous portions 19 of backing means 15, including at least one yarn-like bundle of closely associated and substantially parallel fiber segments in each area of the fibrous web that overlies one of the foraminous portions 19, and a second pattern of substantially aligned fiber segments interconnecting the portions of the fabric in the first pattern. The second pattern corresponds to the configuration of continuous imperforate portions 20 of backing means 15.

If the fibrous starting web 43 is not of too heavy a weight, a third pattern of rearranged fibers may be produced within the first pattern just described. In this type of fiber rearrangement, when fiber segments that are in registry with imperforate portions 20 of backing means 15 are moved into areas overlying foraminous portions 19 of the backing means, fiber segments in the resulting groups of fiber segments that are in registry both with foraminous portions 19 and with forming apertures 31 are moved into areas underlying land areas 32 between apertures 31, and are positioned therein a plurality of yarn-like bundles of closely associated and substantially parallel fiber segments. The third pattern of yarn-like bundles of fiber segments thus arranged within the first pattern of fibers corresponds with the pattern of land areas 32 of apertured forming means 30.

If the fibrous web being rearranged is too heavy, the fibers that are moved by the streams of rearranging fluid from areas of the fibrous starting material overlying imperforate portions 20 of backing means 15 into areas overlying foraminous portions 19 of the backing means will pack the latter areas so full of fibers that no areas of low fiber density, much less any apertures or holes substantially free of fibers, can be produced there. In such a situation, any areas of low fiber density that tend to appear during the fluid rearrangement process will be masked out by the heavy accumulating of fibers. If imperforate portions 20 rise above foraminous portions 19, or in other words the foraminous portions provide depressed areas on backing means 15, a larger number of fibers from a heavier starting web can be accommodated in those depressed foraminous areas without masking or blocking out the areas of low fiber density that tend to appear between the yarn-like bundles of fiber segments that are formed by the fluid rearranging forces.

Above about 400 grains per sq. yd. with fibers of 1 1/2 denier, mats of randomly oriented, helter-skelter fiber segments are ordinarily included in the first pattern of fiber segments in the nonwoven fabric resulting from the practice of this invention.

With imperforate portions 20 raised only slightly above the foraminous portions of the backing means, it has been found that satisfactory formation of yarn-like bundles of fiber segments in the third pattern described just above, with areas of low fiber density clearly delineated between the yarn-like bundles, can be achieved with a fibrous starting material made up of fibers of 1 1/2 denier that has a web weight up to about 600 grains per square yard, or somewhat heavier for higher denier fibers. Between about 600 and about 800 grains per square yard, with fibers of 1 1/2 denier, a full pattern of yarn-like bundles is formed with somewhat less clarity. With a web weight of from about 800 to 1200 grains per square yard, it is ordinarily not possible to form a full third pattern of fiber segments in this manner, but individual yarn-like bundles may be formed in association with the other fiber segments that lie in randomly oriented, helter-skelter relationship to each other in the first pattern of the fabric. With a web weight of 1200 grains per square yard or more, even individual yarn-like bundles are ordinarily not produced. The web weights in question may be somewhat heavier, the higher the continuous imperforate portions rise above the discontinuous foraminous portions of the backing means.

FIG. 5 gives an enlarged fragmentary diagrammatic plan view of the foraminous portion 50 of another backing means that can be used with the apparatus of FIG. 1. Foraminous portion 50 of the backing means for use in this invention is formed of coarse woven screen, preferably metal. In the embodiment shown, wires 51 running vertically in FIG. 5 are straight, while wires 52 running horizontally in that figure weave alternately over and under wires 51. Protuberances 53 are present throughout foraminous portion 50 as the topmost part of each "knee" of a given strand 52 of the screen that is formed as the strand weaves over and under the strands 51 that lie perpendicular to it.

As a given strand 52 slants downward to pass under a strand 51 perpendicular to it, it crosses two other strands 52 disposed on either side of it, as those strands slant upward to pass over the same perpendicular strand that the given strand will pass under. Each series of such "crossing points" 54 forms a trough, such as trough 55 formed by crossing points 54 in FIGS. 5 and 6, that lies between adjacent protuberances 53. The effective shape of troughs 55, as can be best seen in FIG. 6 (which shows a cross section of element 50 of which a plan view is given in FIG. 5), is substantially an inverted triangle.

A series of slightly deeper troughs 56 is formed between adjacent protuberances 53 but extending at right angles to troughs 55. As best seen in FIG. 7, the bottom of each trough 56 is formed by portions of straight strands 51, with successive protuberances 53 on each side of the trough forming the tops of the trough. As seen in FIG. 7, the effective shape of troughs 56 may be characterized as a shallow U-shape.

As shown in FIG. 5, a plurality of troughs 55 and a plurality of protuberances 53 alternate in one direction across the surface of foraminous portion 50 of the backing means. FIG. 5 also shows that a plurality of troughs 56 and a plurality of protuberances 53 alternate in a direction perpendicular to troughs 55. Hence a plurality of troughs and a plurality of protuberances alternate in both the longitudinal and transverse directions across the surface of foraminous portion 50 of the backing means.

Use in the method or apparatus of this invention of a backing means having foraminous portions such as element 50 shown in FIGS. 5 through 7, with a starting web that is not of too heavy a weight, produces a fourth pattern of rearranged fibers within the third pattern already mentioned above. This fourth pattern is made up of yarn-like bundles of fiber segments that have been positioned in troughs 55 and troughs 56 on the surface of foraminous portions 50 of the backing means.

To produce satisfactory rearrangement of fibers into yarn-like bundles of closely associated and substantially parallel fiber segments positioned in troughs 55 and in troughs 56, the vertical distance between the tops of protuberances 53 and the bottoms of the immediately adjacent troughs should be at least about three times, generally no more than about 15 to 20 times, and preferably about five to about ten times, the average diameter of the fibers in the layer of fibrous starting material. For troughs 55, this distance is the vertical distance indicated in FIG. 6 by the pair of dashed lines that pass, respectively, through the tops of protuberances 53 and the crossing points 54 that define the troughs. The vertical distance from the bottom of each trough 56 to the tops of protuberances 53, on the other hand, is somewhat larger, being shown by FIGS. 6 and 7 to be equal to the diameter of a strand 52.

The relative position of a forming aperture 31 and protuberances 53 of foraminous portion 50 of the backing means in one form of the method and apparatus of this invention is shown in dashed lines in FIG. 5. As is seen, aperture 3, in both the longitudinal and transverse directions, has a width somewhat larger than two times the horizontal distance between the tops of immediately adjacent protuberances 53 on foraminous member 50, and spans two such protuberances measured in both the longitudinal and transverse directions.

During use of this invention, apertured forming means 30 and the backing means of which element 50 is a part are spaced to provide a fiber rearranging zone.

Portions of the streams of rearranging fluid that pass through forming apertures 31 and the fibrous web pass directly through openings 57 between adjacent wires of woven screen 50. Other portions of the streams of rearranging fluid that have passed through apertures 31 strike the wires of woven screen 50, at protuberances 53 or at other portions of the wire, and are deflected sidewise before they pass out of the rearranging zone through openings 57.

The streams of rearranging fluid just described move some of the fiber segments that are in registry with apertures 31 and overlie foraminous portions 50 of the backing means into surrounding areas of the fibrous layer, positioning the fiber segments there in yarn-like bundles of closely associated and substantially parallel fiber segments, to define holes or other areas of low fiber density in a pattern corresponding to the pattern of apertures 31. This pattern of yarn-like bundles is referred to above as the third pattern of fiber segments in the non-woven fabric made in accordance with this invention. At the same time, the fluid rearranging forces move other fiber segments that are in registry with forming apertures 31 and overlie foraminous portions 50 into troughs 55 and troughs 56 in element 50, positioning those fiber segments there in yarn-like bundles of closely associated and substantially parallel fiber segments, to define a fourth pattern of bundles of fiber segments disposed within the third pattern just described.

The substantially aligned interconnecting fiber segments that form the second fiber pattern produced by use of the method or apparatus of this invention may be organized in flat, ribbon-like groups of fiber segments. Groups of fiber segments of this type are formed when the distance between two immediately adjacent fluid entry zones (for example, apertures 31 in forming means 30) at their closest spacing is at least about three times the width of an entry zone at its narrowest part. Spacing that is this great tends to interfere with, and destory, the bundling effect of the rearranging fluid that enters the fiber rearranging zone in discrete streams through the spaced entry zones.

With some forms of the invention, the aligned interconnecting fiber segments extending between the groups of fiber segments of the first pattern are further rearranged by deflected streams of rearranging fluid into yarn-like bundles of closely associated and substantially parallel fiber segments. These yarn-like bundles may be parallel with all the other similar bundle lying between and interconnecting a given pair of groups of fiber segments in the first pattern, or they may be organized into a latticework of yarn-like bundles extending between that pair of groups of fiber segments. In these forms of the invention, the spacing between immediately adjacent fluid entry zones is no greater than about two times the width of an entry zone at its narrowest part. With spacing no greater than this, the discrete streams of rearranging fluid entering separate fluid entry zones are effective to produce the described fiber bundling in the groups of aligned fibers that interconnect portions of the fabric in the first pattern.

The rearranged web or fabric produced by the practice of this invention may be treated with an adhesive, dye or other impregnating, printing, or coating material in a conventional manner. For example, to strengthen the rearranged web, any suitable adhesive bonding materials or binders may be included in an aqueous or non-aqueous medium employed as the rearranging fluid. Or an adhesive binder may, if desired, be printed on the rearranged web to provide the necessary fabric strength. Thermoplastic binders may, if desired, be applied to the rearranged web in powder form before, during or after rearrangement, and then fused to bond the fibers.

The optimum binder content for a given fabric according to this 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. In some instances, because of the strength of the fibers used or the tightness of their interentanglement in the rearranged web or fabric, or both, no binder at all need be employed to provide a usable fabric.

The following are illustrative examples of use of the method and apparatus of this invention to produce patterned nonwoven fabrics:

EXAMPLE 1

In apparatus as illustrated in FIG. 1, a web 43 of loosely assembled fibers, such as may be obtained by carding, is fed between apertured forming means 30 and backing means 15. The web weight is about 450 grains per square yard, and its fiber orientation ratio approximately 7 to 1 in the direction of travel. The web contains viscose rayon fibers approximately 1 9/16 inches long, of 1 1/2 inches denier.

The apertured forming belt 30 used in this example has about 165 substantially round holes per square inch, each approximately 0.045 inch in diameter. The width of each of these apertures 31 is thus equal to about 30 times the 0.0015 inch average diameter of the 1 1/2 denier fibers of the fibrous starting material. The holes are arranged in a diamond pattern over the forming means. Each aperture 31 is spaced approximately 0.040 inch in the diagonal direction from the immediately adjacent aperture on the forming belt.

Cylindrical backing drum 15 in the apparatus of this example is constructed of a smooth surfaced metal having foraminous circular portions distributed across its surface in a diamond pattern.

Foraminous portions 19 of backing drum 15 are comprised of a woven nylon screen of approximately 28 .times. 34 mesh or substantially 952 openings per square inch. Each of these foraminous portions 19 has a diameter of approximately 1/4 inch, with a space of approximately 1/8 inch from each portion 19 to the nearest other portion 19 in a diagonal direction.

Discontinuous foraminous portions 19 are interconnected by the continuous metal portions of the drum. These continuous imperforate portions 20, in the area between each pair of immediately adjacent foraminous portions 19, have a central portion 21 that rises 0.012 inch above the plane of the top surface of discontinuous foraminous portions 19 of the backing means, and edge portions 22 that rise about 0.010 inch above the plane described.

Because of the indicated spacing of approximately 1/8 inch between foraminous portion 19 of backing drum 15, it follows that the width of each imperforate portion 20 at its narrowest part is about three times the width of an aperture 31 at its narrowest part.

Except for the diamond patterns of apertures 31 and foraminous portions 19, apertured forming means 30 and backing means 15 are disposed generally as shown in FIG. 4.

Water is projected from nozzles 29 through apertures 31 in apertured forming means 30, and thence through fibrous web 43 and foraminous portions 19 of backing drum 15 into vacuum assist box 45.

After a given portion of fibrous web 43 passes through the rearranging zone, in which streams of water are directed against it as just described, the rotation (in the counterclockwise direction as seen in FIG. 1) of the sandwich comprised of aperture forming belt 30, the rearranged nonwoven fabric 43, and backing drum 15 brings the rearranged fabric to takeoff zone "B." There the rearranged nonwoven fabric leaves the apparatus.

With the conditions indicated, good fiber rearrangement and bundling are obtained, and an excellent nonwoven fabric such as shown in the photomicrograph of FIG. 8, which has a plurality of patterns that alternate and extend throughout the fabric, is produced.

Nonwoven fabric 60 of FIG. 8 contains a first pattern of fiber segments 61 arranged in accordance with the pattern of arrangement of discontinuous foraminous portions 19 of backing drum 15. The nonwoven fabric also contains a second pattern of substantially aligned fiber segments 62 interconnecting the portions of ribbon-like groups of the fabric in the first pattern 61. This second pattern corresponds to the configuration of continuous imperforate portions 20 of backing drum 15.

The fabric also contains a third pattern of yarn-like bundles of fiber segments 63. Each of these yarn-like bundles is formed of closely associated and substantially parallel fiber segments. This third pattern of yarn-like bundles of fiber segments 63 is arranged within the first pattern of fibers 61 in accordance with the pattern of land areas 32 of apertured forming belt 30. Yarn-like bundles 63 define within first pattern 61 a pattern of areas of low fiber density 64 arranged in accordance with the pattern of apertures 31 in apertured forming means 30.

Each group of fiber segments 61 appears from FIG. 8 to be approximately 25 times the size of each area of low fiber density 64, or a little bit larger. This is consistent with the relative size of foraminous portions 19 of backing drum 15 and apertures 31 of apertured forming belt 30 that are included in the apparatus with which the fabric of FIG. 8 was made. Each foraminous portion 19 has a diameter of approximately 1/4 inch, which gives it an area of about 0.197 square inches, and each aperture 31 of apertured forming belt 30 has a diameter of about 0.045 inch, which gives it an area of 0.0064 square inches. In other words, the area of each foraminous portion 19 of backing drum 15 is about 30 times the area of each aperture 31 of apertured forming belt 30.

EXAMPLE 2

FIG. 9 is a photomicrograph of another non-woven fabric made in accordance with the present invention by use of apparatus similar to that described in Example 1, but with a starting web of fibrous material of the type commonly called an isotropic web. The starting material has a web weight of about 350 grains per square yard, and web strength is measured at substantially the same magnitude in every direction throughout the web.

The fabric of FIG. 9 is generally similar to the fabric of Example 1. The respective patterns of fiber segments, as well as areas of low fiber density, that extend throughout the nonwoven fabric of FIG. 9 are indicated by the same designators in that figure as are used in describing the nonwoven fabric of FIG. 8.

In the fabric of FIG. 9, each group of fiber segments 61 appears to be approximately 25 times the size of each area of low fiber density 64, or a little larger. This is consistent, as was true of the fabric of FIG. 8, with the relative size of foraminous portions 19 of backing drum 15 and apertures 31 of apertured forming belt 30 that are included in the apparatus with which this fabric was made.

EXAMPLE 3

In apparatus as illustrated in FIG. 1, a web 43 of loosely assembled fibers, such as may be obtained by carding, is fed between apertured forming means 30 and backing means 15. The web weight is about 320 grains per square yard, and its fiber orientation ratio approximately 7 to 1 in the direction of travel. The web contains viscose rayon fibers approximately 1 9/16 inches long, of 1 1/2 denier.

Apertured forming means 30 has about 165 substantially round holes per square inch, each approximately 0.045 inch in diameter, or about 30 times the average diameter of the fibers of the fibrous starting material. The holes are arranged in a diamond pattern over the forming means. Each aperture 31 is spaced approximately 0.040 inch in the diagonal direction from the immediately adjacent aperture on the drum.

The discontinuous foraminous portions 19 of backing means 15 used in this example are comprised of a woven fiber glass screen of approximately 14 .times. 18 mesh or substantially 252 openings per square inch. Each foraminous portion 19 is square in shape, approximately 5/16 inch on each side, and is spaced from the immediately adjacent similar foraminous portions by approximately 3/32 inch in one direction and about 3/64 inch in the other.

Continuous imperforate portions 20a and 20b of backing means 15 comprise a low density polyethylene mesh or grid of the form shown in plan view in FIG. 10 and in cross section in FIG. 11. The width 66a of each imperforate portion 20a (running vertically in FIG. 10) is approximately 3/32 inch or about 0.094 inch, which is about two times the diameter of each aperture 31 of apertured forming means 30. The width 66b of each imperforate portion 20b (running horizontally in FIG. 10) is approximately 3/64 inch, or about equal to the diameter of each forming aperture 31. Together the grid of imperforate portions defines square foraminous portions 19 each of whose sides 67 is approximately 5/16 inch. The heights 68a and 68b of imperforate portions 20a and 20b are about 1/32 inch and 1/16 inch, respectively, at their rounded top portions 69a and 69b.

With the conditions indicated, good fiber rearrangement and bundling are obtained, and an excellent nonwoven fabric such as shown in the photomicrograph of FIG. 12, which has a plurality of patterns that alternate and extend throughout the fabric, is produced. Nonwoven fabric 70 of FIG. 12 contains a first pattern of fiber segments 71 arranged in accordance with the pattern of arrangement of discontinuous foraminous portions 19 of backing drum 15.

The nonwoven fabric also contains a second pattern of yarn-like bundles of closely associated and substantially parallel fiber segments 72 interconnecting portions of the fabric in the first pattern 71. This second pattern corresponds to the configuration of continuous imperforate portions 20a of backing drum 15. The second pattern in the fabric also contains yarn-like bundles of closely associated and substantially parallel fiber segments 73 interconnecting portions of the fabric in the first pattern. These yarn-like bundles 73 are shorter than bundles 72, because they correspond to narrower imperforate portions 20b of the backing means. Yarn-like bundles 72 define between them areas of low fiber density 74, and bundles 73 define somewhat smaller areas of low fiber density 75. In addition, two groups of bundles 72 and two groups of bundles 73 define on four sides a plurality of large areas of low fiber density 76, which are roughly oval in shape, and correspond to the junctures of imperforate portions 20a and 20b of backing drum 15.

Finally, the fabric contains a third pattern of yarn-like bundles of closely associated and substantially parallel fiber segments 77, arranged within the first pattern of fibers 71 in accordance with the pattern of land areas 32 of apertured forming belt 30. Yarn-like bundles 77 define within first pattern 71 a pattern of areas of low fiber density 78 arranged in accordance with the pattern of apertures 31 in apertured forming means 30.

FIG. 13 is a photomicrograph of the nonwoven fabirc of FIG. 12 taken from the opposite side of fabric 70, showing a different but similar portion thereof. The respective patterns of fiber segments, as well as areas of low fiber density, that extend throughout the non-woven fabric of FIG. 13 are indicated by the same designators in that figure as are used for the corresponding parts of the fabric in FIG. 12.

Each group of fiber segments 71 appears from FIGS. 12 and 13 to be approximately 12 times the size of each area of low fiber density 74, or a little bit larger. This is consistent with the relative size of foraminous portions 19 of backing drum 15 and apertures 31 of apertured forming belt 30 that are included in the apparatus with which the fabric of these figures was made. Each square foraminous portion 19 has a width of approximately 1/4 inch, which gives it an area of about 0.0625 square inches, and each aperture 31 of apertured forming belt 30 has a diameter of about 0.045 inch, which gives it an area of 0.0064 square inches. In other words, the area of each foraminous portion 19 of backing drum 15 is about 10 times the area of each aperture 31 of apertured forming belt 30.

Areas of low fiber density 76 appear from FIGS. 12 and 13 to be roughly 5 to 10 times the size of areas of lower fiber density 74, 75 and 78. It has been found that if the web weight of the fibrous starting material used with the apparatus of this Example is above about 400 grains per sq. yd. with fiber of 1 1/2 denier, large areas of low fiber density 76 are replaced by a latticework of yarn-like bundles defining smaller areas of low fiber density.

EXAMPLE 4

The fibrous starting material and the apparatus employed in this example are the same as those of Example 3, except that the web weight of the starting material is about 460 grains per square yard.

The resulting nonwoven fabric, as seen in FIGS. 14 and 15, is an excellent rearranged fabric having a plurality of patterns of fiber segments that alternate and extend throughout the fabric. With the somewhat heavier weight starting material, the areas of low fiber density in those portions of the web that are in registry both with foraminous portions 19 of backing means 15 and apertures 31 of apertured forming means 30 are not so well defined in this fabric as they are in the lighter weight fabric of Example 3. Another difference between the fabrics of the two examples is in the form taken by the aligned interconnecting fibers that overlie imperforate portions 20 of backing means 15.

Nonwoven fabric 80 of FIG. 14 contains a first pattern of fiber segments 81 arranged in accordance with the pattern of arrangement of discontinuous foraminous portions 19 of backing drum 15. The nonwoven fabric also contains a second pattern of groups of aligned fiber segments 82 that interconnect portions of the fabric in the first pattern 81, and define between them areas of low fiber density 83. An arrangement of yarn-like bundles 84, lighter in weight than groups 82, forms a lattice-work that interconnects portions of the fabric in the first pattern 81. The latticework defines areas of low fiber density 85. Second pattern 82 corresponds to the configuration of continuous imperforate portions 20a of backing drum 15, and latticework pattern 84 corresponds in part to imperforate portions 20b of the backing means, and in part to the areas where imperforate portions 20a and 20b cross each other to form an imperforate grid on the backing means.

The fabric also contains a third pattern of yarn-like bundles of closely associated and substantially parallel fiber segments 86, best seen in FIG. 15. These yarn-like bundles are arranged within the first pattern of fibers 81 in accordance with the pattern of land areas 32 of apertured forming belt 30, and define within first pattern 81 a pattern of areas of low fiber density 87 arranged in accordance with the pattern of apertures 31 in apertured forming means 30.

FIG. 15 is a photomicrograph of the nonwoven fabric of FIG. 14 taken from the opposite side of fabric 80, showing a different but similar portion thereof. The respective patterns of fiber segments, as well as areas of low fiber density, that extend throughout the nonwoven fabric of FIG. 15 are indicated by the same designators in that figure as are used for the corresponding parts of the fabric in FIG. 14.

In the fabric of FIGS. 14 and 15, each group of fiber segments 81 appears to be approximately 12 times the size of each area of low fiber density 87, or a little larger. This is consistent, as was true of the fabric of FIGS. 12 and 13, with the relative size of foraminous portions 19 of backing drum 15 and apertures 31 of apertured forming belt 30 that are included in the apparatus with which this fabric was made.

EXAMPLE 5

In apparatus as illustrated in FIG. 1, a web 41 of loosely assembled fibers, such as may be obtained by carding, is fed between apertured forming means 30 and backing means 15. The web weight is about 400 grains per square yard, and its fiber orientation ratio is approximately 7 to 1 in the direction of travel. The web contains viscose rayon fibers approximately 1 9/16 inches long, of 1 1/2 denier.

The apertured forming means 30 used in this example has about 324 substantially round holes per square inch, each approximately 0.033 inch in diameter or about 20 times the average diameter of the fibers of the fibrous starting material. The holes are arranged in a square pattern over the forming means. Each aperture 31 is spaced approximately 0.022 inch from the immediately adjacent apertures on the forming belt.

The discontinuous foraminous portions 19 of backing means 15 of the apparatus of this example are comprised of a woven nylon screen of approximately 28 .times. 34 mesh or substantially 952 openings per square inch. Each foraminous portion 19 is oval in shape, measuring approximately 1/16 inch in one direction and approximately 1/8 in the other, and is apced about 1/16 inch from the immediately adajcent foraminous portions. Foraminous portions 19 are distributed in a diamond pattern, 24 to the square inch, over backing means 15.

Continuous imperforate portions 20 of backing means 15 comprise a nylon knitted mesh known as Raschel knit fabric, of the form shown in plan view in FIG. 16 and in cross section in FIG. 17. The width 88 of each imperforate portion 20 at its narrowest part is approximately 1/16 inch or about 0.063 inch, which is about two times the diameter of each aperture 31 of apertured forming means 30. Together the grid of imperforate portions defines foraminous portions 19. The height 89 of each imperforate portion 20 is approximately 1/32 inch at its rounded top portion 89a.

With the conditions indicated, good fiber rearrangement and bundling are obtained. An excellent nonwoven fabric such as shown in the photomicrograph of FIG. 18, which has a plurality of interesting patterns that alternate and extend throughout the fabric, is produced. Nonwoven fabric 90 of FIG. 18 contains a first pattern of fiber segments 91 arranged in accordance with the diamond shaped pattern of arrangement of discontinuous foraminous portions 19 of backing drum 15. The nonwoven fabric also contains a second pattern of yarn-like bundles of closely associated and substantially parallel fiber segments 92 that form a latticework interconnecting the portions of the fabric in the first pattern 91. This second pattern corresponds to the configuration of continuous imperforate portions 20 of backing drum 15.

FIG. 19 is a photomicrograph of the nonwoven fabric of FIG. 18 taken from the opposite side of fabric 90, showing a different but similar portion thereof. The respective patterns of fiber segments, as well as areas of low fiber density, that extend throughout the nonwoven fabric of FIG. 19 are indicated by the same designators in that figure as are used for the corresponding parts of the fabric in FIG. 18.

The fabric of FIGS. 18 and 19 also contains a third pattern of yarn-like bundles of closely associated and substantially parallel fiber segments 93, best seen in FIG. 19, that is arranged within the first pattern of fibers 91 in accordance with the pattern of land areas 32 of apertured forming belt 30. Yarn-like bundles 93 define within first pattern 91 a pattern of areas of low fiber density 94 arranged in accordance with the pattern of apertures 31 in apertured forming means 30.

Each group of fiber segments 91 appears from FIGS. 18 and 19 to be approximately eight to ten times the size of each area of low fiber density 94. This is consistent with the relative size of foraminous portions 19 of backing drum 15 and apertures 31 of apertured forming belt 30 that are included in the apparatus with which the fabric of these figures was made. Each foraminous portion 19 has an area of about 0.007 square inches, and each aperture 31 of apertured forming belt 30 has a diameter of about 0.033 inch, which gives it an area of about 0.00085 square inches. In other words, the area of each foraminous portion 19 of backing drum 15 is about eight times the area of each aperture 31 of apertured forming belt 30.

As is best seen from FIG. 19, some fiber segments in groups 91 of the first pattern of the nonwoven fabric of this example are moved into yarn-like bundles of closely associated and substantially aligned fiber segments 95 that are heavier than other such bundles in the fabric, including for example some of the bundles in latticework 92 of yarn-like bundles lying between groups 91. Likewise, some fiber segments overlying continuous imperforate portions 20 of backing means 15 are moved into similar heavier yarn-like bundles 96, which connect adjacent pairs of yarn-like bundles 95. The result is a plurality of undulating patterns of heavier yarn-like bundles 95, 96, 95, 96, etc. extending through the fabric generally in one direction, which in the fabric of FIGS. 18 and 19 is the machine direction of the fibrous starting web.

As indicated above, continuous imperforate portions 20 of backing means 15 rise above the plane of the top of discontinuous foraminous portions 19 of the backing means by about 1/32 inch. This provides a depressed area in each foraminous portion 19 where a larger number of fiber segments may accumulate, which makes heavier yarn-like bundles 95 lying above those foraminous portions still heavier than they would otherwise be. In turn, because the same fibers extend through several successive yarn-like bundles 95, 96, 95, 96, etc., bundles 96 are made heavier than they would otherwise be.

EXAMPLE 6

In this example, the starting material and apparatus used are the same as those of Example 5, except that apertured forming means 30 has about 165 holes per square inch, each approximately 0.045 inch in diameter, arranged in a diagonal pattern with each aperture spaced approximately 0.040 inch from the immediately adjacent apertures on the forming belt.

Discontinuous foraminous portions 19 of backing means 15 are arranged in a diamond pattern in relation to the longitudinal or machine axis of the layer of fibrous starting material being processed. As just indicated, apertures 31 in apertured forming means 30 are also arranged in a diamond pattern in relation to that longitudinal axis. Moreover, the lines that define both these diagonal patterns extend in approximately the same direction. In the nonwoven fabric 100 of FIGS. 20 and 21, the longitudinal axis of the fabric, and thus the longitudinal axis of the fibrous starting web, run in the horizontal direction across the photomicrographs shown. An examination of these two figures shows that lines joining the centers of immediately adjacent discontinous foraminous portions 19 of backing means 15 used in production of the fabric shown extend at an angle 101 of about 33.degree. to the longitudinal axis of the fibrous starting web. Likewise, lines joining the centers of immediately adajcent apertures 31 of apertured forming means 30 extend at an angle 102 of about 34.degree. with respect to the longitudinal axis of the starting web.

Nonwoven fabric 100 of FIGS. 20 and 21 contains a first pattern of fibers 103 arranged in accordance with the pattern of arrangement of discontinous foraminous portions 19 of backing drum 15. The nonwoven fabric also contains a second pattern of yarn-like bundles of closely associated and substantially parallel fiber segments 104 that form a latticework interconnecting the portions of the fabric in the first pattern 103. This second pattern corresponds to the configuration of continuous imperforate portions 20 of backing drum 15.

The fabric of FIGS. 20 and 21 also contains a third pattern of yarn-like bundles of closely associated and substantially parallel fiber segments 105 that are arranged within the first pattern of fibers 103 in accordance with the pattern of land areas 32 of apertured forming belt 30. Yarn-like bundles 105 define within first pattern 103 a pattern of areas of low fiber density 106 arranged in accordance with the pattern of apertures 31 in apertured forming means 30.

In the fabric of FIG. 20, each group of fiber segments 103 appears to be approximately eight to ten times the size of each area of low fiber density 106. This is consistent, as was true of the fabric of FIGS. 18 and 19, with the relative size of foraminous portions 19 of backing drum 15 and apertures 31 of apertured forming belt 30 that are included in the apparatus with which this fabric was made.

FIG. 21 is a photomicrograph of the nonwoven fabric of FIG. 20 taken from the opposite side of fabric 100, showing a different but similar portion thereof. The respective patterns of fiber segments, as well as areas of low fiber density, are indicated by the same designators in the two figures.

As is indicated in FIG. 21, some fiber segments in the portions of nonwoven fabric 100 included in the first pattern of fiber segments 103 are moved into yarn-like bundles of closely associated and substantially parallel fiber segments 107 heavier than other such bundles in the fabric. Likewise, some fiber segments in latticework portions 104 of the fabric corresponding to the configuration of continuous imperforate portions 20 of backing means 15 are moved into similar heavier bundles 108, which connect adjacent pairs of heavier bundles 107 that lie in portions 103 of the fabric in the first pattern that are located diagonally with respect to each other. The result (seen in FIG. 21) is a first plurality of continuous heavier bundles 107, 108, 107, 108, etc. that lie parallel to each other and extend through the nonwoven fabric in a first diagonal direction in relation to the longitudinal axis of the fabric, and a second plurality of similar continuous heavier bundles parallel to each other and extending through the fabric in a second diagonal direction.

The two sets of heavier yarn-like bundles extending in directions diagonal to the longitudinal axis of fabric 100 form an interesting appearance, with the resulting overall pattern being comprised of diagonally disposed smaller apertures 106, relatively light weight yarn-like bundles forming a diamond-shaped gridwork in parts of latticework portions 104, and a superimposed diamond-shaped gridwork of heavier yarn-like bundles of fiber segments. Although this appearance of the fabric can be seen from the photomicrograph of FIG. 21, it is more marked in the fabric itself, since the enlargement used in the photomicrograph tends to de-emphasize the contrast in appearance between the yarn-like bundles of fiber segments of different weights.

FIGS. 22 and 23 are schematic drawings that illustrate how the fibers of the fabric of FIGS. 20 and 21 are rearranged in this example to produce the appearance of a diamond-shaped gridwork of heavier yarn-like bundles. Many fibers in the fibrous web from which the fabric represented by FIG. 22 is made are caused by the fluid rearranging forces that are exerted by streams passing through foraminous portions 19 of backing means 15 to assume the zig-zag pattern of heavy bundles 107 and 108 indicated by the dashed lines in that figure to pass through portions 103 and 104 in the fabric's first and second patterns of fiber segments, respectively. Because of the relative length of the individual fibers, each individual fiber in such groups will extend through a substantial number of successive bundles 107 and 108.

Many other fibers will be positioned in other successions of yarn-like bundles 107 and 108 that form a zig-zag pattern across the fabric that is exactly the same as the first zig-zag pattern except that it is oriented in the opposite direction. Some fibers, depending on the original fiber orientation in the starting web, cross over between these two zig-zag patterns, and extend on to other similar patterns. The combined result of the two zig-zag patterns, as is seen from FIG. 23, is to give the appearance of a gridwork of diamond-shaped openings, some of them defined by heavier yarn-like bundles than the others.

FIG. 20 shows the side of nonwoven fabric 100 that was adjacent backing means 15 during the process of manufacture of this rearranged fabric. Because discontinuous foraminous portions 19 do not rise as far as do continuous imperforate portions of backing means 15, portions 103 of the fabric in the first pattern of fiber segments tend to occupy the resulting depressed spaces above the foraminous portions of the backing means, and as a result fabric portions 103 extend out of the plane of the resulting fabric to give it a three dimensional appearance on the side shown in FIG. 20.

EXAMPLE 7

The starting material for this example is the same as in Example 2. Apertured forming belt 30 used in this example is the same as that in Example 1.

Cylindrical backing drum 15 in the apparatus of this example is constructed of a smooth surfaced metal having foraminous circular portions distributed across its surface in a square pattern. Discontinuous foraminous portions 19 of backing drum 15 are comprised of a woven fiber glass screen of approximately 14 .times. 18 mesh or substantially 252 openings per square inch. Each of these foraminous portions 19 has a diameter of approximately 1/4 inch, with a space of approximately 3/32 inch from each portion 19 to the nearest other portion 19 in a diagonal direction. Discontinuous foraminous portions 19 are interconnected by the continuous metal portions of the drum.

Foraminous portions 19 of backing means 15 are formed as shown in FIGS. 5 through 7. The vertical distance between the tops of protuberances 53 and troughs 55 such as shown in FIGS. 5 and 6 is approximately 0.005 inch, or in other words a little more than three times the 0.0015 inch average diameter of the 1 1/2 denier fibers making up the starting material for this example. The same vertical distance for troughs 56 such as those shown in FIG. 7 is slightly larger.

The horizontal distance between the tops of protuberances 53 is about 0.056 inch in one direction and about 0.071 inch in the other. These distances are equal, respectively, to about 37 times and about 47 times the 0.0015 inch average diameter of the fibers of the fibrous starting material. Each aperture 19 spans a plurality of protuberances 53 on the backing screen, measured in both the longitudinal and the transverse directions. Apertured forming means 30 and backing means 15 are spaced from each other during use of the apparatus of FIG. 1 to provide a fiber rearranging zone therebetween.

Use of the apparatus of this example produces a nonwoven fabric having four patterns of fiber segments that alternate and extend throughout the fabric. As seen in the schematic drawing of FIG. 24, nonwoven fabric 110 has a first pattern of fiber segments 111 arranged in accordance with the pattern of arrangement of discontinuous foraminous portions 19 of backing means 15. A second pattern of substantially aligned fiber segments 112 interconnects the portions of the fabric in the first pattern. A third pattern of yarn-like bundles of fiber segments 113 is arranged within the first pattern 111 to define areas of low fiber density 114.

A fourth pattern of smaller yarn-like bundles of fiber segments 115 is positioned in troughs 55 and 56 of the foraminous portions of the backing means. These yarn-like bundles, lying within areas of low fiber density 114, subdivide those areas further into still smaller areas of low fiber density.

The above detailed description has been given for clearness of understanding only. No unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

Claims

I claim:

1. A method of producing a patterned nonwoven fabric having a plurality of patterns of groups of fiber segments that alternate and extend throughout said fabric, from a layer of fibrous starting material whose individual fibers are in mechanical engagement with one another but are capable of movement under applied fluid forces, which comprises: positioning said layer of fibrous starting material in a fiber rearranging zone, in which fiber movement in directions parallel to the plane of said fibrous material is permitted in response to applied fluid forces, that is defined on one side by forming means having apertures spaced longitudinally and transversely with land areas therebetween, and on the other side by backing means that has foraminous portions arranged in a discontinuous pattern with the foramina therein smaller than said forming apertures and continuous imperforate portions lying between and interconnecting said discontinuous foraminous portions, the width of each of said apertures at its narrowest part being equal to at least about ten times the average diameter of the fibers of the fibrous starting material, the area of each of said discontinuous foraminous portions of the backing means being at least about three times the area of an aperture of said apertured forming means, and the width of each of said continuous imperforate portions of the backing means at its narrowest part being equal to at least about the width of one of said forming apertures at its narrowest part; and projecting streams of fluid through said apertures and then against said fibrous layer to pass therethrough, some of said fluid streams thereafter striking said continuous imperforate portions of the backing means and being deflected thereby in sidewise directions, and all of said fluid streams passing through and beyond said foraminous portions of the backing means, to move some of the fiber segments that are in registry with said imperforate portions of the backing means into areas of said fibrous layer overlying said foraminous portions of the backing means, positioning fiber segments thus moved with other fiber segments in each of said last mentioned areas in at least one yarn-like bundle of closely associated and substantially parallel fiber segments in a location therein underlying said land areas of the apertured forming means, while moving others of said fiber segments that are in registry with said imperforate portions into substantial alignment and in bridging positions extending between said discontinuous foraminous portions of the backing means, thereby forming a nonwoven fabric having a first pattern of fiber segments arranged in accordance with the pattern of arrangement of said discontinuous foraminous portions of the backing means, said first pattern including at least one of said yarn-like bundles of fiber segments in each of the areas of the fabric overlying said foraminous portions, and a second pattern of substantially aligned fiber segments interconnecting the portions of the fabric in said first pattern, said second pattern corresponding to the configuration of said continuous imperforate portions of the backing means.

2. The method of claim 1 in which each of said foraminous portions of the backing means has a plurality of protuberances and troughs alternating across the surface thereof in both the longitudinal and transverse directions, the tops of said protuberances rising above the bottoms of the immediately adjacent troughs by a vertical distance equal to at least about three times the average diameter of the fibers in said layer of fibrous starting material, the horizontal distance between the tops of immediately adjacent protuberances on said backing means being of about the same general magnitude as the distance between the centers of said apertures in the apertured forming means, and in which said streams of liquid move fiber segments that are in registry with said apertures in the apertured forming means and ovelie said foraminous portions of the backing means into surrounding areas of said fibrous layer to position said fiber segments there in yarn-like bundles of closely associated and substantially parallel fiber segments, and move other fiber segments that are in registry with said forming apertures and overlie said foraminous portions into said troughs in the backing means to position said fiber segments there in yarn-like bundles of closely associated and substantially parallel fiber segments, to form a nonwoven fabric having first, second, and third patterns of fiber segments as there defined, with a plurality of areas of low fiber density within said first pattern of fiber segments, and a fourth pattern of yarn-like bundles of fiber segments positioned in said troughs to define a plurality of other areas of low fiber density within said first mentioned areas of low fiber density.

3. Apparatus for producing a patterned nonwoven fabric having a plurality of patterns of fiber segments that alternate and extend throughout said fabric, from a layer of fibrous starting material whose individual fibers are in mechanical engagement with one another but are capable of movement under applied fluid forces, which comprises: backing means having portions that are foraminous and portions that are imperforate, at least 20 per cent of the total area of the backing means being foraminous and the remainder being imperforate, said foraminous portions being arranged in a discontinuous pattern and the remainder of said backing means being imperforate and lying between and interconnecting said foraminous portions; apertured forming means spaced from said backing means to provide a zone in which fiber movement in directions parallel to said backing means is permitted in response to applied fluid forces, the apertures in said forming means being longitudinally and transversely spaced with land areas therebetween, the width of each of said apertures at its narrowest part being at last 0.015 inch, the width of each of said continuous imperforate portions being equal at its narrowest part to at least about the width of one of said apertures at its narrowest part, the area of each of said foraminous portions of the backing means being at least about three times the area of an aperture of said apertured forming means; means for moving said backing means and apertured forming means, with a layer of fibrous starting material positioned therebetween, through a rearranging zone without any translatory motion between said two means and the fibrous layer; and means for projecting streams of fluid through said apertures in the apertured forming means, and then against said fibrous layer to pass therethrough, some of said fluid streams thereafter striking said imperforate portions of the backing means and being deflected thereby in sidewise directions, and all of said fluid streams passing through and beyond said foraminous portions of the backing means.

4. The apparatus of claim 3 in which each of said foraminous portions of the backing means has a plurality of protuberances and troughs alternating across the surface thereof in both the longitudinal and transverse directions, the tops of said protuberances rising above the bottoms of the immediately adjacent troughs by a vertical distance equal to at least 0.005 inch, and the horizontal distance between the tops of immediately adjacent protuberances on said backing means are of about the same general magnitude as the distance between the centers of said apertures in the apertured forming means.