Process for making a non-woven fabric structure

Dec. 16, 1969

A. M. SMITH ll

3,483,601

PROCESS FOR MAKING A NON-WOVEN FABRIC STRUCTURE

Filed July 20, 1965 ₃ Sheets-Sheet 1

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Dec. 16, 1969

A. M. SMITH II

3,483,601

PROCESS FOR MAKING A NON-WOVEN FABRIC STRUCTURE

Filed July 20, 1965

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INVENTOR

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Dec. 16, 1969 a. m. smith ii 3,483,601

PROCESS FOR MAKING A NON-WOVEN FABRIC STRUCTURE Filed July 20, 1965 3 Sheets-Sheet 3

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ATTORNEYS

3,483,601

Patented Dec. 16, 1969

United States Patent Office

3,483,601 PROCESS FOR MAKING A NON-WOVEN FABRIC STRUCTURE

Alexander M. Smith II, Elkin, N.C., assignor to The Fiberwoven Corporation, Elkin, N.C., a corporation of 5 North Carolina

Filed July 20, 1965, Ser. No. 473,316 Inf. Cl. D04h 18/00

U.S. Cl. 28—72.2 20 Claims

ABSTRACT OF THE DISCLOSURE

A process for making a non-woven fabric structure, by utilizing a plurality of webs of loosely matted fibers having a disintegrable carrier interposed therebetween, the webs of loosely matted fibers being needled to form a needled fabric structure with the carrier being disintegrated. The resulting needle fabric structure is stretched thereby further reorienting the needled fabric so as to increase the tensile strength peak of the needled fabric structure in at least the lengthwise direction of the same.

The present invention relates to non-woven needled fabric structures and, more particularly, to an improved process of making a non-woven fabric structure by needling loosely matted fibers of webs or batts while having a disintegrable carrier sandwiched or interposed between the webs, and then disintegrating the carrier and stretching and setting the fabric structure to produce a fabric structure characterized by good tensile strength and didimensional stability and tensile strength characteristics direction.

The present invention is an improvement over the process and fabric structure disclosed in the U.S. Patent No. 3,154,462, issued Oct. 27, 1964, and entitled “Non-woven Fabric and Process of Making the Same.” In the aforementioned patent, a plurality of webs or batts of loosely matted fibers, preferably cross-laid, and having a foun- 40 dation of a scrim or warp interposed therebetween were delivered to a needle loom wherein the fibers of the webs or batts were oriented in cohering entanglement, preferably according to the teachings of my U.S. Patents 3,090,099 and 3,090,100 both issued May 21, 1963, and ⁴³my U.S. Patent 3,112,552 issued Dec. 3, 1963. After needling of the webs or batts into a needled fabric structure, the resultant fabric structure was stretched and permanently set lengthwise of the same so that the warp of the foundation was permanently stretched. By perma- ³θ nently stretching the warp, the fibers, which had been previously oriented during needling were further reoriented in a warp-wise or lengthwise direction so as to shift the tensile strength peak of the fibers to a point where it reinforced the tensile strength peak of the warp. ⁵⁵

While the process and the novel article of the aforementioned application are extremely satisfactory the process and article of the present invention is an improvement thereover as the present invention has still further advantages and unexpected results in that the non-woven ^eoneedled fabric structure produced has increased fiber entanglement due to action of the needling and increased dimensional stability and tensile strength characteristics in both a lengthwise and crosswise direction. Also, the process of the present invention produces a needled fabric structure having no appreciable visible needle lines prior to napping and, thus, the fabric structure may be used for many end textile products wherein napping is unnecessary.

An important object of the present invention is to provide an improved process for making nonwoven needled ‘° fabric structures from at least two webs or batts of loosely matted fibers having a disintegrable carrier interposed or sandwiched therebetween prior to needling, the process increasing the effectiveness of the needling as well as providing an improved stress-strain profile in a lengthwise direction and in a crosswise direction.

Another object of the present invention is to provide an improved process for making a nonwoven fabric structure from a plurality of webs of loosely matted fibers having a disintegrable carrier therebetween prior to needling, the carrier being disintegrated and the pieces of the carrier integrating with and cohering to the oriented fibers to effectively increase the dimensional stability in both a lengthwise and crosswise direction, and further shift the tensile strength peaks of the fabric structure toward a point or zero elongation of the fabric structure.

Ancillary to the immediately preceding object it is a further object of the present invention to provide an improved process of making an improved non-woven needled fabric structure in which the tensile strength peak of the fabric structure in a lengthwise direction is shifted toward 20 a point of zero elongation substantially the same as the point where the tensile strength peak in a crosswise direction is shifted toward a point of zero elongation thereby providing over-all dimensional stability.

Still another obpect of the present invention is to pro25 vide a process for making an improved nonwoven needled fabric structure having less lengthwise and crosswise stretch than heretofore realized.

A further important object of the present invention is to provide a process for making an improved fabric struc30 ture, the final fabric structure having high strength characteristics and yet being sufficiently porous to make it capable of end uses such as in blankets, wearing apparel, artificial leather, floor coverings, drapes, and upholstery products or the like.

Still another object of the present invention is to provide an improved process for making an improved nonwoven needled fabric structure in which a carrier, interposed between webs of loosely matted fibers prior to needdling, is used; the carrier making it possible to needle the loosely matted fibers while the fibers are in a completely relaxed state, so that better fiber entanglement from initial orientation of fibers is obtained.

Ancillary to the preceding object, it is a further object to provide an improved process for making an improved non-woven needled fabric structure which can utilize an inexpensive material for the carrier, the process resulting in the product having appreciably no visible needle lines.

A still further object of the present invention is to provide a non-woven fabric structure having less stretch and more strength in both a lengthwise and crosswise direction.

These and other objects and advantages of the present invention will appear more fully in the following specification, claims and drawings in which:

FIGURE 1 is a diagrammatic side elevational view illustrating a system for producing a non-woven needled fabric structure according to the present invention;

FIGURE 2 is an enlarged fragmentary perspective view of a piece of the fabric structure made according to the present invention, the fabric structure being pulled apart at a corner and diagrammatically illustrating the disintegrated carrier integrated with the oriented entangled fibers;

FIGURE 3 is a view taken substantially on the line 3—3 of FIGURE 2 and further illustrating the integrating of the disintegrated carrier with the oriented entangled fibers;

FIGURE 4 is a diagrammatical side elevational view illustrating a modified system for producing the nonwoven needled fabric structure according to the present invention, the view illustrating the use of a beam of warp and the wetting of the fabric structure by a solvent spray rather than immersing;

3,483,601

FIGURE 5 is a stress-strain graph illustrating the lengthwise and crosswise tension curves for a piece of prior art needled fabric structure having an acrylic warp;

FIGURE 6 is a stress-strain graph illustrating the tension curves in lengthwise and crosswise directions of a prior woven fabric structure;

FIGURE 7 is a stress-strain graph illustrating the tension curves in lengthwise and crosswise directions of a needled fabric structure of the present invention having a disintegrable paper carrier and prior to disintegration of the carrier;

FIGURE 7 is a stress-strain graph illustrating the tenfabric structure as FIGURE 7 but illustrating the tension curves of the fabric structure after the carrier has been disintegrated;

FIGURE 9 is a stress-strain graph similar to FIGURE 7 but illustrating the tension curves of a needled fabric structure made according to the present invention and utilizing a carrier made of a viscous rayon warp before the warp is disintegrated; and

FIGURE 10 is a stress-strain graph similar to FIGURE 8 but illustrating the tension curves of the needle fabric structure of FIGURE 9 after the carrier of viscous rayon warp has been disintegrated.

Referring now to the drawings wherein like character and reference numerals represent like or similar parts and, in particular, to FIGURE 1 the process of the present invention broadly contemplates sandwiching a disintegrable carrier 10 between two or more webs or batts 12 and 14 of loosely matted fibers, then passing the webs and the interposed carrier through a needle loom 16 wherein the loosely matted fibers of the webs 12 and 14 are oriented into interlooping and interlacing entanglement with one another to form a needled fabric structure 18. After the needled fabric structure is formed, this structure then passes through a first pair of feed rollers 20 into a tank 22 containing a solvent 23 for the carrier 10, such as water or the like when the carrier is, for example paper, and a pair of guide rollers 24, the fabric structure emerging from the tank and passing through a second pair of feed rollers 26. While the needled fabric structure 18 is between the feed rollers 20 and 26 respectively and immersed in the tank it is being stretched and the carrier 10 is being distintegrated. The stretching is accomplished by rotating the feed rollers 26 at a faster speed than the feed rollers 20.

It will be understood that the webs or batts 12 and 14 may be continuously fed from conventional carding machines where the fibers are carded and loosely formed into webs, or the webs may be supplied from rolls of such material after the material has been taken from such carding machines and formed into rolls. Preferably, as disclosed in the aforementioned Patent No. 3,154,462, the webs or batts 12 and 14 have a majority of their loosely matted fibers cross-laid with respect to the direction of feed of the webs through the needle loom 16 and the rollers 20. Also as disclosed in the aforementioned Patent 3,154,462, the fibers of the webs 12 and 14 may be made of synthetic fibers such as rayon, nylon, Acrylon, Orlon or the like, or natural fibers such as wool, cotton or the like, or blends of different synthetic fibers or different natural fibers or blends of both. To this extent the subject matter disclosed in the aforementioned Patent No. 3,154,462 is incorporated by reference herein. Also, it will be appreciated that synthetic and natural fibers other than those specifically mentioned can be utilized in the process of the present invention whenever such fibers may have physical characteristics enabling them to be needled so long as the fibers do not have physical characteristics incompatible in the process with regard to the disintegration of the carrier 10.

For the purposes of this specification the term “carrier” is intended to cover any disintegrable material capable of supporting the webs as they pass through the needle loom 16 so that the fibers of the webs are iij a com pletely relaxed condition when subjected to needling. Further, the term “carrier” is intended to include a sheet material, a scrim having at least a warp of disintegrable material or just a warp and the term “warp” is intended to cover filaments or a web of long fibers or fibers spun into yarn or threads of a scrim extending in a lengthwise direction. The term “warp-wise” is synonymous with the term “lengthwise” and relates to a direction of the fabric structure parallel to the direction which the fabric struc₁₀ ture passes through the needle loom 16 whereas the term “crosswise” is a direction of the fabric structure transverse to the direction which the fabric structure passes through the needle loom 16. In other words, the term “crosswise” is somewhat synonymous with the term “fill15 ing-wise” as used with respect to a woven fabric.

The carrier 10, as mentioned above, must be easily disintegrable to accomplish the process and result in the improved needled fabric structure of the present invention. In this respect the term “carrier” differs from the 20 term “foundation” as used in the aforementioned U.S. Patent No. 3,154,462, as the latter term is intended to cover a structure which remains substantially intact in the final fabric structure. A preferable material for the disintegrable carrier is paper such as tissue paper, crimp 25 paper, toweling paper, newsprint paper or the like. Additionally, the disintegrable carrier 10 may be preferably made from cellulosic fiber material such as cotton, viscose rayon or the like. Manifestly, the material used for the carrier must have characteristics of (1) losing 30 its strength and disintegrating when wet by a solvent, (2) losing its strength when wet by a solvent and disintegrating when stretched, (3) easily disintegrable when stretched (this includes not only the breaking of fibers but the slipping of fibers past one another during stretching), 35 (4) disintegrable when needled or (5) easily disintegrates on a combination of any of the above.

Referring now to FIGURES 1 to 3 inclusive, the process will now be described in more detail utilizing specific materials for the webs 12 and 14 and the carrier 10 40 as an example in the typical system disclosed. The webs 12 and 14 were made up of loosely matted fibers of rayon, the rayon fibers of the webs 12 and 14 being cross-laid when the webs passed through the needle loom 16. The disintegrable carrier 10 was made from a sheet 45 of crimp paper and fed from a roll 30 of the same between the upper web 12 and the lower web 14 to provide a sandwich-like structure just prior to entrance in the throat of the needle loom 16. When the sandwichlike structure passes through the needle loom 16, the 50 rayon fibers of the webs 12 and 14 were oriented in a manner similar to that described in my aforementioned patents so that they were in cohering chain entanglement with each other. Some of the fibers of the web 12 were entangled with fibers of the web 14 whereas some of the 55 fibers of web 14 were entangled with fibers in the web 12 due to the penetrating action of the upper and lower sets of needles of needle loom 16. Since the paper sheet forming the carrier 10 was a material easily disintegrated, the needles of the needle loom easily perfo60 rated the paper carrying with them the fibers during the process entangling the fibers. Unlike a needled fabric structure with a foundations made up of a scrim having at least a warp, there was no deviation of the path of the needles of the needle loom 16 as they passed through 65 the carrier and, consequently, a more complete and uniform entanglement of fibers resulted without any appreciable visible needle lines appearing on the surfaces of the needled fabric structure.

After the webs 12 and 14 with the paper carrier 10 70 had been needled into the needled fabric structure 18, the needled fabric structure 18 was then wetted and simultaneously subjected to a stretching in its lengthwise direction in order to completely disintegrate the papet carrier 10 into very small pieces of particles 19 and to 75 further reorient the previously oriented fibers. An un3,483,601 usual feature of the process and product resulting therefrom is that the stretching of the needled fabric structure 18 at least while wet not only breaks down the paper carrier 10 into the pieces 19 but also results in the fibers of the layers being further reoriented in a crosswise as well as lengthwise direction.

The stretching of the needled fabric structure 18 in a lengthwise direction reduces its overall crosswise width and its thickness but, as in disclosure of my aforementioned U.S. Patent No. 3,154,462, the crosswise contraction is not as great as the lengthwise extension and there is, effectively, a gain in area of needled fabric structure produced by a given needle loom. Of course, the weight per area of the fabric structure reduces with the gain in area of the same.

Additionally, it has been found that the stretching and permanently setting of the needled fabric structure 18 need only be in a range in the order of 10 to 30% greater than its orginal length to obtain a resultant needled fabric structure having less lengthwise and crosswise stretch with more and substantially uniform strength in both directions. The stretching and setting of the needled fabric structure 18 insures that the disintegrated carrier 10 or the pieces of paper, in fact, almost fibers of paper, are thoroughly integrated with and cohere to the entangled fibers of the fabric structure.

Referring now to FIGURES 5 through 10, the various graphs disclose comparative tests between (1) a prior needled fabric structure having a foundation (FIGURE 5), (2) a prior art woven fabric structure (FIGURE 6) and (3) a needled fabric structure made according to the present invention (FIGURES 7 through 10 inclusive).

FIGURE 5 illustrates the stress-strain profile of a prior art needled fabric structure utilizing an over-all fiber content of 94% rayon and 6% acrylic fibers. The webs were made of loosely matted rayon fibers and were needled with a foundation of acrylic warp threads. The resulting fabric structure had a weight of 10 ounces per square yard. The solid line curve represents a tension curve wherein a pulling force was exerted on the fabric structure in a lengthwise direction. It will be noted that the solid line curve of FIGURE 5 has two tensile strength peaks A and B which represent respectively the points of failure of the acrylic warp threads and the force peak or tensile strength peak of the fiber entanglement after breaking of the warp threads. The peak A shows that failure of acrylic warp threads occurred at an approximate pulling force of 24 pounds at an accompanying elongation of the fabric structure to approximately 35% of the original length of the piece of fabric being tested. To the right of peak A there was a drop off of pulling force as the material was further elongated until such a time that fiber entanglement took over to provide the strength necessary to require additional pulling force for additional elongation. At peak B, the maximum pulling force or tensile strength of fiber entanglement was reached and from that point on there was failure of the strength of fiber entanglement.

The broken line curve of FIGURE 5 illustrates that in the crosswise or “filling-wise” direction of the fabric there is but one peak C as the warp does not enter into the strength in this direction. However, it will be noted that the fiber entanglement takes over almost immediately upon application of a pulling force and reaches the peak C with a pulling force of approximately 35 pounds with a resultant elongation of the fabric in a crosswise direction of 60% of its original width.

FIGURE 6 illustrates the prior art relative to a conventional woven fabric structure made from fibers of 94% rayon and 6% acrylic. In a woven fabric structure the application of pulling force in a lengthwise direction reached its peak at D which was at approximately 15% elongation of its original length with a force of approximately 37 pounds. At this point the warp-wise yarn of the woven fabric structure broke and there was a rapid drop off of strength. The crosswise strength curve of the woven fabric structure of FIGURE 6 is shown in broken lines and it will be appreciated that the strength of a woven blanket in a crosswise direction is materially less than it is in a lengthwise direction. The crosswise strength peak occurred at the point E wherein the filling threads or yarn broke down at approximately 35% of the fabrics original width with only 8 or 9 pounds pulling force.

FIGURES 7 and 8 represent comparative curves for a piece of fabric made according to the present invention, one piece (FIGURE 7) being tested prior to disintegration of the crimp paper carrier 10 and the other piece (FIGURE 8) being tested after disintegration of the paper carrier. The weight of the fabric before disintegration of the paper carrier and stretching of the same was 12 ounces per square yard. The weight of the fabric after disintegration of the paper carrier and stretching of the same was 10.9 ounces per square yard and thus this sample of needled fabric, which was made of rayon fibers needled on a crimp paper carrier, provides a good comparison with the prior art needled and woven fabrics discussed above. It is also well to note that this sample had none of the advantages of the prior art samples which accrue from use of acrylic fibers. In FIGURES 7 and 8 the full line curves in each instance represent testing of the respective fabric in the lengthwise direction whereas the broken line curves represent the testing of the fabric in a crosswise direction or width. It will be noted that in FIGURE 7 a tensile strength peak F caused by the entanglement of fibers occurred at about 76% of its original length with a pulling force of 22 pounds whereas a tensile strength peak in a crosswise direction occurred at G which was approximately 67 % of its original width with a pulling force of 26 pounds. While the fabric structure in FIGURE 7 has a very adequate peak strength, it is not particularly desirable as too much elongation or stretching in both lengthwise and crosswise directions occurred before the tensile strength peaks were reached.

Referring now to FIGURE 8 wherein the fabric of FIGURE 7 had been wetted and the paper carrier disintegrated and the fabric stretched, it will be noted that the tensile strength peaks H and I in lengthwise and crosswise directions of the fabric increased and decreased. The lengthwise tensile strength peak H increased from 22 pounds to 28 pounds whereas the crosswise tensile strength peak only decreased from 26 pounds to about 24 pounds. However, it should be noted as it is more important, both tensile strength peaks H and I respectively had for the fabric structure shifted downward toward the respective zero percent elongation from the strength peaks G and F and the area under both curves is greater indicating more strength with less elongation. In more detail, the tensile strength peak H in a lengthwise direction occurred at only 57% of elongation of the original length as compared to the strength peak F at 76% whereas the tensile strength peak I also shifted downwardly to a point where it occurred at 55% as compared to the strength G of 67%. Further, it will be noted that the tensile strength peaks H and I occurred substantially at the same percentage of elongation of their respective lengths and widths thereby insuring that the fabric structure had substantially the same dimensional stability in both directions.

The tests referred to above were compiled from tests conducted on a Thwing-Albert Strength Tester utilizing one inch wide strip samples cut so that a tensile pulling force could be applied in the desired direction. A pulling force was applied and recorded as the jaws of the tester, initially spaced at three inches, separated at a speed of twelve inches per minute.

While the process and fabric structure made therefrom and described with respect to FIGURES 1-3 refers to the disintegration of the paper carrier 10 as occurring during the wetting of the needled fabric structure 18 by immersion in the water 23 of tank 22 and stretching between the feed rollers 20 and 26, it will be appreciated

3,483,601 that disintegration of the carrier can be accomplished by needling, wetting or stretching alone or partially by needling, wetting and/or stretching. Also, it is within the scope of the present invention that wetting of the needled fabric structure 18 may be accomplished by spraying rather than immersion. However, it is an essential feature of the invention that regardless of how the carrier is distintegrated, the needled fabric structure must be stretched and permanently set in its stretched condition with the carrier 10 disintegrated therein.

Referring now to FIGURE 4 there is disclosed a slightly modified system for accomplishing the process and producing the fabric structure of the present invention. In FIGURE 4 the webs 12 and 14 of loosely matted fibers of rayon are fed from cards or the like and have sandwiched therebetween a warp 10' of rayon delivered from a beam 30'. The webs 12 and 14 with the individual threads or yarns of the warp 10' sandwiched thereby are fed through the needle loom 16 where they are needled in a manner described and the needled fabric structure 18' is fed from the needle loom through the pair of feed rollers 25. A spray nozzle 32 sprays solvent onto the needled fabric structure 18' thoroughly wetting the same prior to its passing between a first pair of stretch rollers 20' and a second pair of stretch rollers 26'. This softens or reduces the strength of the rayon warp 10'. A tank 22' placed under the fabric structure catches the excess solvent dropping therefrom.

Stretching is accomplished in a similar manner to that described with respect to FIGURE 1. The pairs of rollers 25 and 20' respectively operate at the same speed whereas the pair of rollers 26' operate at a faster speed. Since the solvent saturating the needled fabric structure 18' reduces the strength of the rayon threads or yarn of the warp of carrier 10', such threads break into small pieces as the needled fabric structure passes between the pairs of stretching rollers 20' and 26'. It will be appreciated that the length of breakage of the threads of the warp can be controlled by the distance between the pairs of rollers 20' and 26' as well as by controlling the differential in speed of the rollers.

FIGURES 9 and 10 represent stress-strain graphs for a piece of needled fabric structure made according to the system disclosed in FIGURE 4, the webs being made of rayon fibers and the warp being made of a viscose rayon. In FIGURE 9 the test was made prior to the disintegration of the warp threads of foundation 10' and discloses that the fabric had a tensile strength peak J of 26 pounds in a lengthwise direction when the fabric had elongated 76% of its original length. The broken line curve of FIGURE 9 represents the tests being conducted on the fabric crosswise of the same and discloses that the fabric had a tensile strength peak K of 46 pounds and an elongation of the same of 45% of its original length. In FIGURE 10 the fabric of FIGURE 9 had been subjected to disintegration of the threads of the warp 10' as well as stretching and permanently setting of the needled fabric structure 18'. In this figure it will be noted that the tensile strength peak L of 27 pounds for the needled fabric in a lengthwise direction occurred when the fabric had elongated 41% of its original length, whereas the broken line curve shows that the fabric structure had a tensile strength peak M of 45 pounds in a crosswise direction when it had elongated to 32% of its original length. Both tensile strength peaks L and M illustrate the shifting of the strength peaks downward toward zero percent of elongation.

The process of the present invention as heretofore described produces a needled fabric structure especially adaptable for end uses such as blanket fabrics, apparel fabrics, drapery fabrics, upholstery fabrics and artificial leather. The use of a carrier which is easily disintegrable results in better needling characteristics to provide for a more uniform fiber entanglement and additionally provides for a fabric structure having little or no visible nee die lines on the surface thereof. Further disintegrating the carrier and having the pieces of disintegrated carrier integrated and comingle with the fibers of the webs in the needled fabric structure provides for dimensional stability in both lengthwise and crosswise directions, and an increase in strength with less stretch in the final fabric structure.