US 3329556 A
Description (OCR text may contain errors)
y 4, 1967 R. J. MCFALLS ETAL 3,
NON-WOVEN FABRIC AND METHOD OF MECHANICALLY WORKING SAME Filed Oct. 25, 1963 4 Sheets-Sheet l TEAM WATER F I G 4 INVENTORS RICHARD J. MC FALLS CHARLES L. ADAMS LESLIE L. TURAI y 4, 1967 R. J. M FALLS ETAL 3,329,556
NONWOVEN FABRIC AND METHOD OF MECHANICALLY WORKING SAME Filed Oct. 23, 1963 4 Sheets-Sheet 2 FIG. 8
INVENTORS RICHARD J. MC FALLS mil-W14 l I I0 July 4, 1967 R. J- M FALLS ETAL NON-WOVEN FABRIC AND METHOD OF MECHANICALLY WORKING SAME Filed Oct. 23, 1963 FIG. l5
l0 win-11m 4 Sheets-Sheet 3 FIG. l6
INVENTORS RICHARD J. MC FALLS CHARLES L. ADAMS LESLIE L. TURAI y 4, 1967 R. J. MCFALLS ETAL 3,329,555
NON-WOVEN FABRIC AND METHOD OF MECHANICALLY WORKING SAME Filed Oct. 23, 1965 4 Sheets-Sheet 4 x Fr I50 m -l35 GRAMS I00 2 o: o
I 50- E x (n o I I I I I lNCHES CHART TRAVEL x 1: E 60- -56 GRAMS 0 I I 4 3 2 l O CHAk T T R' AVEL FIG. l8
INVENTORS RICHARD J. MC FALLS CHARLES L. ADAMS LESLIE L.TURAI United States Patent N ON-WOVEN FABRIC AND METHOD OF MECHANICALLY WORKING SAME Richard J. McFalls, Troy, and Charles L. Adams, Waterford, N.Y., and Leslie L. Turai, East Palatka, Fla., assignors, by mesne assignments, to Clupak, Inc., New
York, N.Y., a corporation of Delaware Filed Oct. 23, 1963, Ser. No. 317,409 8 Claims. (Cl. 161-170) The present application is a continuation-in-part of our co-pending application, Ser. No. 160,519 filed Dec. 19, 1961 and entitled, Non-Woven Fabric and Method of Mechanically Working Same and now abandoned.
This invention relates to non-woven fabrics that are formed predominantly or entirely of textile fibers that are bonded randomly to one another by small discrete particles of an added polymeric material or at crossover or contacts between thermoplastic fibers by heat and which has improved kinesiological properties over prior non-woven fabrics made of the same materials.
Non-woven fabrics of textile fibers are random webs of natural or synthetic textile fibers bonded by polymeric systems and have had rather limited use, one objection thereto being their stiffness in simple bending and resistance to deformation under complex stresses such as encountered in bodily movement. Consequently, the handle of non-Woven fabrics is liable to be harsh and such fabrics do not drape well. The achievements of softness and draping properties, without loss of strength has been a major obstacle to a more extensive and wider use of non-woven fabrics. An interlocked web heretofore has been inherently a stiff structure which does not drape and fold in all directions as easily as woven fabrics. Non-woven fabrics are customarily formed by laying or dispersing in the loose textile fibers on a moving support, and hence the fibers are guided in the direction of their lay to some extent by initial contact of the ends of the fibers with the moving support which may cause them to lie largely in the direction of movement of the support, which would be the length of the fabric. Such fabrics when supported solely by a central area tend to flex or fold along an axis that is generally parallel to the length of the fabric, which is the direction in which most of the fibers lay.
The use of non-Wovens as primary fabrics, demanding a high degree of flexibility, drape and response to bodily movement has been severely hampered or prevented by the stiffness or boardiness which has up to now been considered inherent in these products.
An object of this invention is to provide an improved, non-woven fabric predominantly or entirely of textile fibers, which will be soft to the touch, or feel, which will have greater tensile strength and kinesiological properties than similar fabrics as heretofore made, which will have increased tensile strength in width, which when supported by a small interior area thereof will flex easily and quite equally in directions crosswise of its face, which will have drape and hand characteristics quite similar to woven fabrics, which will be relatively inexpensive to make, which may be sterilized and packaged for uses where they can economically be discarded after a few uses, and which will be relatively quiet when folded or flexed and so be useful as expendable garments.
Another object is to provide an improved, simple, and relatively inexpensive method for imparting those properties to non-woven fabrics of this type.
Other objects and advantages will appear from the following description of an example of the method and improved fabric, and the novel features will be particularly pointed out in connection with the appended claims.
In the accompanying drawings:
FIG. 1 is a microphotograph of the fiber arrangement Patented July 4, 1967 in a local area of a typical non-woven fabric as received from the maker, and before treatment in accordance with this invention;
FIG. 2 is a similar microphotograph of this fiber arrangement of a local area of such a fabric after it has been treated in accordance with the principles of this invention.
FIG. 3 is a schematic illustration, on a much larger manner in which a typical non-woven fabric depends from a support attached centrally thereof;
FIG. 6 represents schematically a scale that when connected to the rod that pulls the fabric through a ring, indicates the force necessary to pull the fabric through one stage of its passage through the ring;
FIGS. 7 to 10 are similar views showing successive steps of drawing the ordinary non-woven fabric through a ring and indications of the forces necessary to do the drawing at the different stages, and the drape or manner of hanging which the fabric acquires during and after such drawing;
FIGS. 11 to 16 are views similar respectively to FIGS. 5-10 but when using a typical non-woven fabric like that used in connection with FIGS. 5-10, but after treatment in accordance with the principles of this invention;
FIG. 17 is a chart made by a force recording device that directly recorded the forces exerted in drawing through an aperture in FIGS. 510 of non-woven fabric before its compacting treatment in accordance with the principles of this invention; and
FIG. 18 is a similar chart made in the same manner and using a similar non-woven fabric after its compaction treatment in accordance with this invention, but using a difierent scale due to the lower forces necessary.
In accordance with this invention, a non-woven fabric formed of laid textile fibers that are bonded randomly to one another at intervals by fusing or by small, discrete I added particles of a polymeric material, is subjected to compression and compacting forces, entirely between its faces in a direction parallel to a face dimension of the fabric, that compact, crowd, flex and rearrange the fibers together in such direction of compaction with stretches of fibers between their points of bonding to other fibers, also locally flexed, crimped or bent laterally of their lengths. During such subjection to compaction and compression forces, pressure is also applied to the opposite faces of the fabric in directions normal to such faces, adequate to inhibit or prevent creping of the fabric.
As one example of the invention, a non-woven fabric formed of 100% viscose ray-on, carded, staple, textile fibers that were bonded at intervals to one another at points of contact by small, separate or discrete particles from a water based, 10% acrylic resin emulsion, was slightly moistened by placing blotters uniformly dampened with water in contact with its faces for about four seconds. The moistened fabric was subjected to treatment according to the method of this invention. First it was passed 7 through apparatus for compressing it progressively endwise to com-pact, crowd together and crimp or flex its fibers upon themselves in' a direction parallel to a face of the fabric and entirely between the previously existing faces of the fabric. One simple and very satisfactory apparatus for this purpose is illustrated in FIG. 4.
In this apparatus a heated, cylindrical drum or roll 1 is mounted for idle rotation on its axis. An endless belt 2 of elastic rubber passes between one peripheral sector of the roll and a stationary bar or compactor 3 which is adjustable toward and from the roll in a direction approximately radially of the drum or roll 1. The belt is driven lengthwise at a selected speed by driving rolls 4 and 5 between which the belt passes. Suitable idlers, one of which is shown at 6, guide the belt in its endless travel between the roll 1 and bar 3. Water under pressure is supplied by pipe 7 to the bar 3, and by conduits within that bar to the surface of the bar that is in contact with the belt to provide water as a lubricant between the bar and the belt. The bar 3 is adjusted toward the roll 1 until a nip between the belt and roll is established and the periphery of the roll is indented somewhat into the elastic surface of the belt. The belt on its surface that engages the bar has a web reinforcement that restricts lengthwise stretching of the belt along the reinforced face, but permitting local stretching of the other elastic face that abuts the roll 1.
The non-woven fabric 8, while somewhat moistened, is fed between the periphery of roll 1 and the belt in the direction in which the belt is being driven at the roll 1, and passes through the nip between the belt 2 and the roll 1 for a wrap distance around the periphery of the roll of about 20 to 30 and then is removed from contact with both the roll and the belt.
In passing through the nip between the belt and the roll, the non-woven fabric frictionally adheres to the surface of the belt passing the nip, and as the elastic belt surface contracts in so passing, the fabric is compressed or compacted lengthwise progressively along its length. Since the pressure on the fabric which is normal to its faces restricts the fabric from becoming materially thicker due to the lengthwise compression, the fibers are crowded and compacted together, rearranged and crimped or flexed locally all within the space between the faces of the fabric. This causes more of the lengths of the fibers to lie crosswise of the length of the fabric and thus increase the resistance to bending of the fabric crosswise of the direction of the fibers that lie lengthwise of the fabric, and increases the widthwise tensile strength of the fabric.
The fabric after passing the nip is separated from both the belt and roll so that it can dry, and it then is guided away and dried by suitable driven drying rolls Q, one of which is illustrated in FIG. 4. These rolls 9 are arranged in series to one another and the fabric passes over them in succession. The rolls 9 withdraw the treated fabric from the nip and convey it in an approximately tensionless or slack condition so that the pull on the fabric is so small that it does not stretch out much of the compaction and crowding that was placed in it at the nip.
In a successful and satisfactory example, the roll 1 was heated for best results, to a temperature in the range of approximately 110 F. minimum to 130 F. maximum, and it is about 2 /2 feet in diameter. The belt was about 1 to 2 inches, preferably about 1% inches in thickness and the rubber of it had a Shore Durometer hardness of 70. The minimum hardness of the belt for the best results on the fabric was about 50 Shore, but a hardness of 70 Shore or a little more gave somewhat better results. The linear speed of travel of the belt was varied from about 10 feet to 200 feet per minute. The pressure of the bar 3 against the belt was sufficient to create a to 18% reduction in the thickness of the belt at the nip.
Referring next to FIG. 1 which illustrates a microphotograph of a face of a small portion of a non-woven fabric of carded, staple 100% viscose rayon textile fibers bonded by a water based 10% acrylic resin emulsion, as it was received from the maker and before compaction and treatment in accordance with this invention. It will be noted that the fibers of this fabric predominantly lie in one direction which would be the direction in which the support moved as the carded fibers were deposited thereon.
FIG. 2 is a microphotograph of a small face portion of such a fabric after it has been passed through apparatus, such as shown in FIG. 4, during which the fibers were compacted and crowded together in a direction lengthwise of the fabric and also flexed and rearranged locally. It will be noted that the treatment in the appartus such as shown in FIG. 4, has increased the number of crosswise disposed fibers in a unit area, so that the fibers now offer about as much resistance to flexing in one direction as another, and with more fiber stretches now disposed crosswise of the length of the fabric the widthwise tensile strength has been substantially increased. It will also be noted that the fibers, particularly those disposed to extend generally lengthwise of the fabric, have also between points of bonding to one another been locally bent, flexed or crimped in sidewise directions.
This last is more clearly demonstrated schematically in FIG. 3 where the full lines represent a few staple textile fibers A, B, and C bonded together by discrete particles of resin where they cross one another at D, E, and F. The dash lines a, b and c represent the positions and shapes of the fibers A, B, and C respectively after the fabric has been compressed and compacted and its fibers rearranged in accordance with this invention.
Assuming that bond point D remained relatively stationary, it will be noted that bond point E has moved to the position e and bond point F has moved to the position 1. This shortens the distance between the bond point D and the new positions e and f of bond points E and F and hence the fibers A and B are bent, flexed, or collapsed randomly laterally upon themselves as shown by dash lines and b. The bond points E and F also moved closer together to positions e and 1 hence fiber C was also flexed or bent sidewise upon itself locally as shown by the dash line c.
A sample of such non-woven fabric was cut into 10" diameter specimen pieces and FIGS. 5-16, made from photographs of actual tests, illustrate the difference in the drape characteristics or kinesiological properties of such a fabric as made and also after compaction treatment in accordance with this invention. The device for making this comparison of such drape characteristics is not a part of this invention and hence is not described or illustrated in all details of construction. This comparison apparatus employs a horizontal, fixed ring 10 having an aperture 11 from face to face thereof of about 2%, inches diameter. A rod 12 depends through the aperture 11 and at its lower end it carries a pedestal or clamp 13 of about 1% inches diameter whose sections engage with and clamp to opposite faces of a small central area of the dry specimen .piece 14 formed of such non-woven, rayon staple, textile fiber fabric as first made, and before compacting treatment in accordance with the method of this invention. The pedestal or clamp is smaller in diameter than the diameter of the aperture 11 in the ring 10 so that the clamp and specimen piece 14 may pass through the aperture with only a small clearance. A scale 15 with indicator 16 is connected in any suitable manner to the rod 12 to measure and indicate the force required to pull the clamp 13 and specimen piece 14 through the aperture. The pointer or indicator 16 designates the force in pounds required at each step in pulling the non-woven specimen piece through the aperture 11. FIG. 5 indicates the start of the test and the indicator in FIG. 6 shows no force applied. FIG. 7 indicates an early intermediate step in pulling the specimen piece partially through the aperture of the ring and the pointer of the scale in FIG. 8 shows that a force of 200 grams was required to get the specimen piece through aperture 11 to the extent indicated in FIG. 7.
In FIG. 9 the fabric specimen has been pulled entirely through the ring and the force required at the completion is again zero. It will be noted from FIG. 5 that the fabric specimen depends from the clamp like a paper would depend if held on a pencilflat against the under face of the paper. The non-woven fabric here has flexed along an axis that is parallel to the length of the fabric and to the direction in which a preponderance of the fibers lay. In other words, the non-woven fabric specimen 14 hangs in a U-shape from the circular clamp 13. As this fabric is drawn through the aperture 11 it forms folds or cusps as shown in FIGS. 7 and 9.
FIGS. 11-16 correspond in steps to FIGS. 5-10 except that the non-woven fabric specimen 14a is identical with the specimen 14 except that it has been treated or compacted in accordance with the method of this invention. As shown in FIG. 11 the non-woven fabric specimen piece 14a, which was identical with specimen piece 14 except that it has been compacted and processed in accordance with the method and this invention, no longer hangs in the shape of a U but depends or drapes quite uniformly all around, under no force as shown by the pointer on the scale in FIG. 12. As the fabric specimen piece 14a is drawn partially through the aperture 11 as shown in FIG. 13 to the same extent as the fabric specimen 14 in FIG. 7, the processed specimen piece 14a drapes more easily and vertically than the unprocessed specimen did in FIG. 7. Note that the force required to pull the processed specimen piece 14a through the aperture 11 to the same extent as the unprocessed specimen, now requires only 30 grams of force to do it, in contrast to the 200 grams of force required to .pull the unprocessed specimen to the same extent. When the processed specimen piece 14a was pulled completely through the aperture as shown in FIG. 15, the specimen depended in a better drape and formed predominantly more cusps than did the unprocessed specimen as shown in FIG. 9.
From these operations shown in FIGS. 5-16, it appears that the drape characteristics and kinesiological properties of the non-woven fabric are greatly improved by treatment or processing in accordance with this invention. It was also discovered that whereas normally compaction of paper reduces its strength, when the non-woven fabrics formed of staple textile fibers was compacted in accordance with this invention, the tensile strength was actually increased and the toughness also increased remarkably. For example, when a non-woven fabric formed of staple textile was given an 8% compaction, the improved drape characteristics were satisfactory and the tensile strength was increased by approximately 13% and the toughness by approximately 70%. The improved drape and kinesic characteristics compare favorably with standard broadcloth woven fabric.
Referring next to FIGS. 17 and 18, the forces required to pull a non-woven fabric formed of staple. textile fibers are graphically illustrated. In pulling a circular specimen of such non-woven fabric through the aperture 11, as in FIGS. 5-10, using the fabric as made and before compaction, the forces required at each step of. the pulling are indicated by the graph. The graph of FIG. 18 had to be made on a different scale than the graph'of FIG. 17 but the forces necessary to pull the compacted specimen through the aperture 11 are noted on the chart. It will be noted from a comparison of FIGS. 17 and 18 that the maximum break force necessary to pull the specimens through the aperture for the specimen as made and before compaction in accordance with this invention, was about twice that required for the compacted specimen, and that at the draw, the force required for the uncompacted specimen was also about twice that required for a similar specimen after compaction. The force required immediately following the break fell off more rapidly for the compacted specimen than it did for the uncompacted specimen.
The term drape as used hereinabove, defines a purely static property in describing the manner in which a fabric falls when hung or placed on a form, or the property of falling in graceful folds. The term hand or handle can best be explained as the feel of a fabric when held, felt, folded or crushed in ones hand. The action of a fabric specimen as it is pulled through the aperture 11, may be described as a kinesiological action in that it is one manner of comparing the physical movements including quantitative, qualitative and positional changes, in the fabric when pulled through an aperture.
The term non-woven as applied to fabrics is commonly used to describe materials made primarily of textile fibers held together by an applied bonding agent or by the fusing of self-contained thermoplastic fibers, and which are not processed on conventional spindles, looms or knitting machines. They are textile-like structures having a web or mat of fibers in which the fiber is greater than about A; inch in length and the fiber content is at least 50% of the fabric weight. The fibers are held together with bonding agents which constitute at least 10% of the total fabric weight. Staple fibers are usually those which are in length from about /2 inch to about 1% inches. In some such non-woven fabrics, several superposed webs of textile fibers are laid to form the complete web of the fabric. The fibers used are usually the same as may be used in woven fabrics and may include cotton fibers as well as fibers of various synthetics such as are used for making woven fabrics. The resins or bonding agents which are applied to the fibers in non-woven fabrics may not be fibers but small, separate and discrete particles that bond the fibers to one another randomly at contacts between abutting or crossing fibers or some or all of the fibers may be thermoplastic and/or thermosetting so as to bond to one another by heat. Some of these added bonding agents include thermoplastic resins, some thermosetting resins and some both types. During the compaction, with the fabric being in contact wit-h the preferably heated drum, the thermoplastic resin fibers or particles may soften and rebond the contacting fibers to some extent.
In the manufacture of non-woven fabrics it is postulated that different portions of the bonding agent solidify at different times and create in the final fabric stress combinations which inhibit bending or flexuring of certain of the fabric, particularly in a direction transversely of the fabrics, and that the compacting operation on such a fabric relieves the fabric of its internal stress concentrations.
In the compaction of non-woven fabrics in accordance with this invention, the moisture condition of the fabric at compaction is important for the best results. The application of such moisture to the fabric is best controlled by applying the moisture as a steam cloud to the fabric just before the fabric reaches the nip as is shown in FIG. 4, where a steam pipe 10 extends widthwise below the fabric about 2 feet before the fabric reaches the nip between the belt and heated drum. This pipe 10 has one long or a series of shorter apertures or slots that discharge a cloud of steam against the under face of the non-woven fabric.
The application of moisture in the form of steam may be said to be important and variable for each type of non-woven fabric in that:
(1) Running of the web under ambient conditions can result in some compaction.
(2) Addition of the steam treatment results in increased compaction with improved surface character.
(3) The amount of steam used is specific to each combination of fibers and bonding material.
(4) Process variables in the manufacture of nonwovens are such that the character of the individual roll of fabric in a single shipment may determine the amount of steam required.
(5) The steam curtain is normally within two feet of the nip.
(6) At to 200 ft. per minute web speed, it can be seen that there is little opportunity for penetration of moisture into the fiber and for bonding material.
(7) Adsorbed water, not a wet film, is most likely the condition on the fabric created by the steam, with the amount quite important. It is postulated that as soon as the adsorbed water exhibits wetness, the water acts as a lubricant preventing maximum compaction.
(8) Adsorbed Water is essentially dry in that it is only a few molecules thick. This acts as a partial softener of the surface of the fibers and plasticizer or sensitizer of the surface of the bonding material, without destroying the frictional relation between the fabric and the compacting belt and drum.
(9) Excessive steam or moisture results in occluded water or wet fiber and bonding material surfaces. The severely reduced compaction can be explained by the reduced frictional relation between the non-woven and the compacting components.
(10) Spraying with a fog of water, re-rolling and equilibrating over night does not produce as good results in that control of the amount of moisture is inadequate.
This invention is also applicable to a somewhat different type of non-woven fabric in which some or all of the bonding between textile fibers is obtained by inclusion in the web of fibrilated synthetic fibers such as Dacron or nylon and others. These fibrilated fibers, when included, serve to mechanically bond the system to form a unitized whole. Exposure to sufficient heat can cause adhesive bonding between fibers and fibrids to give added strength to the fabric.
It is noted that when using fibrids of the Dacron and nylon type that increased temperatures are required to achieve the desired degree of compaction.
Such synthetic fibrids are available on the open market, for example from E. I. du Pont de Nemours of Wilmington, Del., under the trade name of Textryl. Such webs are known under the trade name of Textryls.
It will be understood that while carded laid webs have been specifically mentioned, the random-laid webs of textile fibers may be compacted in accordance with this invention to improve their drape and kinesiological properties within the broadest concept of the invention.
It will be understood that various changes in the details, steps, materials and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.
1. The method of producing a fabric having improved drape, handle and strength which includes the steps of:
(a) taking a preformed non-woven fabric web having staple textile fibers randomly bonded together at contacts between said fibers by at least about 10% of the total fabric weight of a resinous polymeric material,
(b) moisture conditioning said web to assure a partial softening of the resinous polymeric material,
(0) continuously moving said conditioned web to a confining means including an elastic surface, and
(d) while confined, contracting said elastic surface whereby due to the frictional adherence, said web is caused to contract and compress lengthwise thereby causing the fibers to be rearranged and locally flexed and crimped in upon themselves between the points of bonding with one another,
(e) heating said fabrics simultaneously with said confining,
(f) removing the web having the rearranged fibers from the confining means,
(g) and moving the web in an approximately tensionless condition to a drying means, and
(h) further drying the Web.
2. A fabric product produced by the method of claim 1.
3. The method according to claim 1 and exposing both faces of said compressed fabric to air immediately after such compression.
4. The method of claim 1 and wherein:
'(a) said heating is conducted at a temperature of between about F. and F.
5. The method of claim 1 and wherein:
(a) said moisture condition of said web results in a web having a moisture content exceeding the normal moisture content possessed under average room atmospheric unsaturated conditions.
6. The method of claim 4 and wherein:
(a) said drying is carried on at an initial temperature of about 250 F.
7. The method of claim 1 and wherein:
(a) said resin is an acrylic resin emulsion.
8. The method of claim 1 and wherein:
(a) said staple fibers are 50% of the total fabric weight.
References Cited UNITED STATES PATENTS 2,319,834 5/ 1943 Wallach 2618.6 2,373,194 4/1945 Luttge 16173 2,531,931 11/1950 Arkell 161128 2,624,245 1/ 1953 Cluett 161206 2,765,513 10/1956 Walton 2618.6 3,101,294 8/ 1963 Fridrichsen 162206 XR 3,122,469 2/ 1964 Freuler 264-280 XR 3,148,108 9/1964 Cluett 206 XR FOREIGN PATENTS 1,237,528 6/1960 France.
' ALEXANDER H. BRODMERKEL, Primary Examiner.
ALEXANDER WYMAN, Examiner.
W. POWELL, P. E. ANDERSON, Assistant Examiners.