US3255064A - Process for mechanical crimping of fibers in sheet form - Google Patents

Description

June 7, 1966 M. MAKANSI PROCESS FOR MECHANICAL CRIMPING OF FIBERS IN SHEET FORM Filed July 17, 1961 2 Sheets-Sheet l LIMITED DRAW LIMITED DRAW FORM WEB FORM WEB 4 CRIMP AND SET CRIMP AND SET W l A BOND INVENTOR MUNZER MAKANSI ATTORNEY June 7, 1966 MAKAN$| 3,255,064

PROCESS FOR MECHANICAL CRIMPING OF FIBERS IN SHEET FORM Filed July 17, 1961 2 Sheets-Sheet 2 FIG-6 FIG-5 FIG-4 INVENTOR M U NZER HAKANSI ATTORNEY United States Patent $255,064 PROCESS FOR MECHANICAL CRIMPING 0F FIBERS IN SHEET FORM Munzer Makansi, Wilmington, DeL, assignor to E. I. du Pont tie Nemours and Company, Wilmington, Del., a corporation of Delaware Filed July 17, 1961, Ser. No. 124,616 12 Claims. (Cl. 156-466) This invention relates in general to nonwoven webs of fibrous elements and, more particularly, to an improved processing method for producing such nonwoven Webs having superior properties.

In the following specification, and in the claims, the term fibrous elements is intended to include any filamentary material of the type appropriate to the textile art including any fibril, fibrid, fiber, filament, thread, yarn, or filamentary structure regardless of length, diameter, or composition although, in preferred form, the invention relates particularly to synthetic organic polymeric fibrous materials and, more especially, to such materials in the form of continuous filament-s.

The term web includes mats, lbatts, nonwoven pile fabrics, and other interfelted, interentangled or commingle-d fibrous products which may generally be described as coherent sheets of entangled fibers made without the fibers first being spun intoyarns and the yarns later interlaced by weaving, knitting, braiding, or other means of yarn manipulation.

In the production of nonwoven webs of fibrous elements, at number of basic problems exist with respect to fiber distribution, retention of structural integrity, and attainment of desired properties in terms of end-use function and aesthetics. It has been the experience of those skilled in the art that the parameters in their desirable ranges, more often than not, are mutually exclusive. Attaining one object in full often seems to require missing another object completely. As a result, the nonwoven structures known in the present state of the art are the result of prudent, although not always felicitous, compromises in balancing one set of objects against another.

For example, it is desirable to produce nonwoven structures from a multiplicity of continuous filaments of synthetic organic polymeric materials, thereby taking advantage of the reduced manufacturing costs inherent in such a procedure as well as producing structures of greatly increased strength and having other useful and distinctive properties. The copending application of Kinney, S.N. 859,614, filed December 15, 1959, and now abandoned sets forth a process of distributing continuous filaments to form a web composed of fibrous elements disposed in random nonparallel arrangement.

To impart certain appropriate aesthetic properties to nonwoven structures, notably soft hand and good drape, it has been found desirable to highly crimp the individual fibrous elements as set forth in the copending application of Guandique, et al., S.N. 859,640, filed December 15, 1959, and noW Patent No. 3,117,055. However, it also has been found that imparting the desired high crimp to the individual elements prior to distribution in the web interferes with such distribution and, while processes for producing in situ the desired crimp level have been found, as set forth in the reference applications, a simple, effective, and inexpensive process employing largely mechanical means has not been known prior to this present invention. Attempts to act upon the entire web structure by the known processes for mechanically indenting complete matted fibrous pads and the like have not resulted in nonwoven structure-s in which substantially all the individual fibrous elements have a high degree of dition, the products of the prior art have been characterized by a low degree of uniformity.

It is an object of the present invention to provide an improved process for treating a nonwoven web of uncrimped fibrous elements to produce a nonwoven structure 'of uniformly highly crimped fibrous elements having soft hand and good drape.

Further, it is an object to treat such a web by simple, inexpensive, and largely mechanical means.

Additionally, it is an object to crimp in situ, and to a relatively high level of crimp, substantially all of the fibrous elements in a nonwoven weib of randomly distributed uncrimped fibrous elements.

Yet another object is to provide a process for treating a nonwoven web of randomly distributed uncrimped continuous filamentary fibrous materials of synthetic organic polymeric material to produce a high and uniform level of crimp in situ.

It is yet another object of this invention to provide an arrangement for treating a nonwoven web of randomly distributed uncrimped fibrous materials of synthetic organic polymeric material, said web having bonding material therein, to produce a bonded nonwoven structure of highly crimped fibrous elements.

Further objects and advantages will be apparent from the description hereinafter.

In accordance with this invention the objects are attained by a process for producing a nonwoven structure of highly crimped fibrous elements preferably of synthetic organic polymeric materials and still more preferably of continuous filaments, comprising partially drawing fibrous elements and forming a web of these elements, disposed in uncrimped random nonparallel arrangement, and subjecting this web to compressive and shearing forces in a multiplicity of spatially distributed areas distributed upon at least one of the surfaces of the web, the forces being of sufiicient magnitude to further draw the individual fibrous elements locally and crimp them to a high crimp level, and simultaneously heating the web uniformly and sufficiently to facilitate crimping and set the fibrous elements and then optionally, where, ordinarily, suitable binder material has been distributed in the web, subjecting the thus-drawn and crimped web to heat to produce a bonded nonwoven structure, and, optionally, embossing the surface thereof to provide further aesthetic properties.

The present invention is described in further detail below in connection with the accompanying drawings in which:

FIGURE 1 is a flow sheet of a preferred process according to the invention,

FIGURE 2 is a flow sheet of an optionally preferred process according to the invention,

FIGURE 3 is a diagrammatic representation of apparatus arranged in a system for processing articles under the principles of the invention,

FIGURE 4 is a view in projection of an enlarged fragmentary portion of a crimping surface used in practicing the process of the instant invention,

FIGURE 5 is a top-plan view of an enlarged frag- 3 Referring to the drawings, FIGURE 1 is a flow sheet of the process for practicing the invention. From a source of fibrous elements 1, the elements are forwarded and partially drawn 2 in a uniform manner, and then forwarded to the forming step 3 in which there is laid down a web of randomly distributed: uncrimped fibrous ele ments. This web is then forwarded to the crimping and setting step 4 wherein the web is subjected to compressive forces in a multiplicity of spatially distributed compressive areas, disposed upon at least one of the surfaces of the web, these forces selectively being of sufi'icient magnitude to locally draw the individual fibers to a high state of crimp. Meanwhile, the web is uniformly heated to a level suflicient to facilitate crimping and set the fibrous elements while undergoing the crimping action. process produces a coherent web in which the individual fiber-s are highly crimped, the entire structure having aesthetic properties of soft hand and exhibiting a high degree of drape.

Where it is desired to produce a web structure having softness and drape with good retention of properties, it is known to bind the final structure by any one of a number of well-known means. To achieve such a product, the process of FIGURE 2 may optionally be used, in which there is withdrawn from a source of fibrous elements 1 and a binder material -1", which later may be liquid, particulate, or preferably fibrous in form, sufficient materials and in appropriate proportions, and these are forwarded through drawing step 2 wherein the fibrous elements are drawn partially, as before. The fibers so treated This.

thence are forwarded to process step 3 in which there I is formed a web, as before, nonwoven and of randomly distributed uncrirnped fibrous elments, which web is forwarded to process step 4' in which the elements are crimped and set, the crimping forces and temperatures being selected so that bonding does not occur during this process step. The material then, in the form essentially of the product of the process of FIGURE 1 with the exception of the binder material distributed therein, is forwarded to process step ,5 in which bonding occurs by any of the' known methods, as will be set forth in greater detail further on in this specification. It is also possible toself-bond webs of thermoplastic materials having no binder therein by appropriate adjustment of the bonding conditions, as is well known.

Referring now to FIGURE 3 in which is shown a schematic arrangement of apparatus elements adapted to producing products by processes of either FIGURE 1 or FIGURE 2 numerals 6 and 6 are representative of sources of fibrous elements and binder in the form of fibrous elements respectively. Sources of fibrous elments 6 and 6' may be spinning heads of any of the well-known types adapted to the continuous spinning of filamentary materials, and, to a person versed in the art, it will be apparent that associated equipment requisite to the proper functioning of such spinning heads and dependent upon the particular chemical and physical nature of the filaments spun are not indicated in the present schematic drawing.

of drawing mechanisms but preferably an air jet device as schematically indicated. Charged filaments 11 are then deposited upon'moving belt 13 in an appropriate manner to form a nonwoven web 15 in which the uncrimped fibrous elements are disposed in randon nonparallel arrangement. 1

Moving belt 13 may be foraminous or not, as appropriateto the particular product handled and, as described in the Kinney application, may be grounded electrically or oppositely charged by means of electrical device 14. The web 15 so formed moves in the direction of the arrow on belt 13 and may optionally 'be'consolidated to facilitate handling. This consolidation may be accomplished by pressing web 15 as it is carried on belt 13 between lightly loaded presser roll 16 and the downstream drive roll 17 of belt 13. Greater consolidation may be obtained by further passing web 15 through the nip between downstream drive roll 17 and the second consolidation roll 18 which ordinarily would be more heavily loaded than roll 16, and still further consolidation may take place in a third nip point between roll18 and roll 19 which latter roll may be heated if this requirement is appropriate. Web 15 may then be passed to a windup device, not shown, and a package wound up in any manner known to the art for transportation to further processing, or, as is shown in the schematic of FIGURE 3, passed, along path 44 shown as a dotted line, in a continuous manner around guide roll 20 to mechanical crimping device 21 passing through cooling lips 45. Cooling lips 45 are connected to a source of cooling liquid, not shown, which liquid is circulated internally entering and leaving through ports 46 and 47. In mechanical crimping device 21, web 15 is passed between the nip of rolls 22 and 23. Means for applying and regulating the loading in this nip, and in the other nips of the figure, are provided but not shown. Roll 23 is shown as having an elastomeric cover 24 thereon, and roll 22 is so disposed as to provide a multiplicity of compressive forces spatially distributed upon one of the surfaces of web 15. It is apparent that this may be done by providing the surface of roll 22 with some form of tessellation in which protuberances which may be pegs and clear areas alternated according to an appropriate pattern. A form of such a surface is shown in projection in FIGURE 4, which is representative of a small enlarged portion of the surface of roll 22. The pattern is shown uniformly distributed upon thesurface 24 of the roll as a multiplicity of pyramidal pegs 25 of depth D and pitch spacing P. It should be noted here that the uniform pitch spacing P of FIGURE 4 is not a requisite of the invention, although it is a preferred form, and that other spacings may suggest themselves to practitioners of the art for achieving purposes common to that practice. Similarly, pegs 25 might well be disposed upon moving belts rather than upon surfaces of rolls such as roll 22, and still further, intermeshing rolls might be employed as the equivalent of opposing roll 22 by elastomeric covered roll 23. Furthermore, other forms of pegs or protu'berances, screens for example, may be used. Experiencewill suggest other variations of elements that will be equivalent to the basic process herein disclosed. Experience has shown, for example, that a number of crimping operations may be requisite, and hence there is indicated in the schematic of FIGURE 3 a second crimping operation between rolls 23' having elastomeric cover 24' and roll 22', the rolls being disposed on diametrically opposite sides of web 15 as compared to rolls 22 and 23. A preferred crimping surface is shown in FIGURES 5 and 6. Pegs 40 have peaks 41 formed of truncated spheres. Similarly, the roots 42 are semi-circular in cross section while the flanks 43 are planar, tapering inward from root 42 to peak 41. The pitch to depth ratio of this surface is 1:1. The surface of FIGURES 5 and 6 has been found to provide more uniform properties in the end product and is particularly useful in minimizing anisotropic characteristics.

The process of the instant invention requires that simultaneously with the application of pressure in spatially distributed compressive areas, there be supplied heat of a suificient magnitude to facilitate crimping and set the crimp. The elevated temperature also limits static electricity which otherwise produces a web which is too lively and fuzzy to further handle. Thus, mechanical crimipng device 21 is shown with cover 26 and heating device 27. In practice, a number of heating means may be employed to achieve the desired result, providing appropriate quantities of heat are supplied and their distribution and level is controlled properly. For example, rolls 22 and 23 may be internally supplied with steam heat, or alternatively, convectors may be used or similar devices within enclosure 26, or heating device 27 maybe any of a number of known radiant heating devices heating either the surface of the roll or the surface of web or both, or further, any combination of these means or other wellknown means might be used to supply uniform heat in a controlled fashion to web 15 as it passes through the nip of rolls 22 and 23.

Where it becomes desirable in terms of end-use for the web to be bonded, web 15 is preferentially forwarded through cooling lips 48 to bonding and embossing device 28 which is appropriately enclosed within covering structure 29. Cooling lips 48 are appropriately connected to a circulating cooling-liquid system, not shown, by ports 49 and 50. Advancing web 15 is carried into the nip between processing belt 30, which is driven in the direction of the arrow, and heated roll 31, belt 30 being backed up at the nip by roll 32. Processingbelt 30 is partially wrapped about the periphery of heated roll 31 and maintained in that position by rolls 32, 33, and 34, and belt 30 is urged against roll 31 by appropriate means not shown in the drawing. Within the nip between belt 30 and heated roll 31, Web 15 is heated to a level sufficient to activate the binder material, which results in discrete bonding. If then it is desired to impart an aesthetically appealing surface pattern, web 15 is then preferentially forwarded into the nip between embossing rolls and 36, which are urged one against the other, by means not shown in the drawing, with a force sufficient to indent the surfaces of the web While the binder elements may or may not be still activated to fix the surface as desired. Rolls 35 and 36 may be similar to roll 22 in formation or could be foraminous metallic structures such as screens or, without departing from the teachings of this invention, could be a combination of a deeply profiled roll with a roll having an elastomeric or similar yielding surface. Embossing rolls 35 and 36 may be internally heated and, for reasons of temperature control, may be enclosed separately from covering structure 29. Between roll 33 and the nip between rolls 35 and 36 there may be an intermediate enclosure, separately temperature controlled, to regulate the temperature gradient therebetween. Web 15 is then forwarded to a windup device, not shown on the sketch, where it is wound into a package 37 upon core 38. To insure appropriate heat transfer conditions in bond embossing device 28, suitable heating devices, indicated schematically in the drawing by heating device 39 may be employed. In addition to direct heating of roll 31, similar direct heating of rolls 35 and 36 may be required or desired. Similarly, en-

closure 29 may be insulated or supplied with a heating jacket. Furthermore, the order of processing through bonding and embossing device 28 is a matter of skilled choice, and, as will be apparent to those conversant with the art, .it may be more appropriate to emboss between rolls 35 and 36 prior to bonding between belt 30 and heated roll 31.

Wher it becomes desirable in terms of end-use for the bonded and embossed web to have exceptional bulk, the process outlined in FIGURE 7 may be employed. Having been spun, laid down, consolidated, stabilized, and mechanically crimped in a manner according to that shown in FIGURE 3, the web emerging from mechanical crimping device 21 and shown in FIGURE 7 as 15' is passed to a mechanical working device 92 wherein at ambient room temperature web 15 is squeezed between screen roll 69 and elastomeric covered roll 70. Screen roll 69 is covered with a relatively coarse mesh screen 71 and screen 71 is urged by biasing means not shown acting on roll 69 against web 15 which is backed up by a moderately soft elastomeric cover 72 surfacing roll 70. Web 15' is then carried into embossing device 73 wherein at elevated temperature an appropriate embossing pattern in placed upon the surfaces of web 15, as the web passes into the nip between rolls 74 and 75 which are biased one against the other by means not shown and whose surfaces are appropriately patterned or ornamented or the like. Embossing device 73 is appropriately heated, schematically indicated in FIGURE 7 by electrical heating device 76 although any of the known equivalents might be used, and embossing device 73 is appropriately enclosed as indicated by enclosure 77. The elevated temperature in embossing device 73 is maintained below the critical temperature at which fiber to fiber bonding will occur. Web 15', emerging from embossing device 73, is carried into bonding device 78, passing into a mild nip between belt 79 and belt 80, both of which belts move in the direction of the arrows. Belts 79 and 80 may be fabricated from metal screen or asbestos cotton cloth or the like, as is well known. Belt 79 passes from roll around the periphery of heated roll 82 and then over roll 87 and under tensioning roll 86 which, by means not shown, may be biased in a manner regulating tension in belt 79. Belt 80 passes over roll 81 and then is carried over the arcuate surface of heat transfer device 88, which latter, by means not shown, may be appropriately heated. Thence belt 80 passes around heated roll 82 and over the arcuate surface of heat transfer device 89 which may be heated or cooled by means not shown, and belt 80 is then turned around roll 83 and around biasing roll 84 which by appropriate means may be properly tensioned as indicated schematically by the Weight W in FIG- URE 7. In bonding device 78 the temperature that the web achieves is regulated by appropriate heat input to heat transfer devices 88 and 89 and roll 82. Herein the temperature is so regulated that the binder material is activated and, upon emerging into a cooler zone or in passing over heat transfer device 89 when optionally it is acting as a cooling device, the activated binder in web 15 is cooled and bonds are achieved in the Well-known manner. Web 15 is then rolled up into package 90 winding on core 91 by means not shown.

It will be apparent to those familiar with the processing of nonwoven webs that equivalents to the devices illustrated in FIGURE 7 are well known, for example, the action of bonding device 78 may readily be accomplished on a pin tenter by interleaving the advancing web between sheets of cloth or by supporting the web on a single cloth. Furthermore, the embossing rolls 74 and 75in embossing device 73 may well be appropriate combinations of one surface acting against a yieldable surface and, where it is desired to pattern both surfaces, at least two pairs of such rolls may be employed to act first on one surface and then the other.

While the processes shown in FIGURES 3 and 7 are preferred processes and are continuous in nature, the objects of this invent-ion can readily be achieved by a batch or step process. Similarly, the rotary devices employed can be replaced within the purview of the invention by translating plates providing other conditions are maintained equivalent. Further, the shape of the crimp obtained during this process is dependent upon the contour of the rotary or translating crimping device and can be of any desired shape such as sawtooth, sinusoidal, or the plateau and valley type which would result from protuberances 25 of FIGURE 4. Where both sides of the web are mechanically crimped and where other crimpinducin g mechanisms are active, the crimp shape may be altered and the frequency increased from that of the crimping devices.

The crim-p discussed herein may be characterized as a macrocrimp or permanent alteration of filament structure having a frequency not in excess of crimps per inch and more usually in the range of 10-100 crimps per inch and having a gross displacement transverse to the fiber axis of from 0.008 inch to 0.125 inch. In addition to this structure, observation under a microscope shows.

indication of a microcrimp structure. This apparently results from high contact forces at cross-over points of fiber on fiber. The frequency of the microcrimps is in excess of 130 crimps per inch, and the amplitude of the microcrimps is relatively shallow as would be expected from the impression or indentation of one fiber on another fiber. The microcrimp contributes to drape by reduction of the effective bending modulus of the individual fibers through indentations at a multitude of points along the fiber length. The macrocrimp, in itself however, produces the desired properties and results from following the process of the invention. As set forth previously, the crimp level is desired to impart flexibility to webs without sacrificing strength and other physical properties.

Webs, according to this invention, are characterized by having tensile strength in excess of 5 lb./in./oz./yd. tongue tear strength in excess of 0.7 lb./o-z./yd. and a vibration modulus not in excess of 300 0 p.s.i.

Vibration modulus is a measure of web stiffness. It is determined in a dynamic test involving measurement of the resonance frequency of a strip of the material when subjected to a forced vibration. The sample is clamped at one end to a sinusoidally oscillating support and the frequency in cycles per second at maximum amplitude of vibration is measured either by an oscillograph or some counting device. The modulus is then calculated from the formula:

where V.M is the vibration modulus in pounds per square inch, P is the density in grams per cubic centimeter, C is the observed frequency at resonance in cycles per second, L is the sample length in inches, and t is the sample thickness in mils. The lower the modulus, the more flexible the sample.

Nonwov-en webs having such extreme flexibility and strength are useful in such fields as protective coverings and in upholstery when in combination with vinyl and the like, and in fields presently restricted to woven fabrics.

It has also been indicated previously that attempting to obtain a high level of crimp by the known-method of pressing raw webs composed of undrawn fibers between plates or in calender-type rolls results in failure. Structures achieved by this approach are excessively stiff and unsatisfactory and not suitable for many fields in which more expensive woven fabric base materials are presently used. Similarly, attempts to highly crimp webs made from fibers highly drawn to achieve high tenacity resulted in failure.- number of broken filaments. Surprising-1y, it was found that, for fibers in a nonwoven web structure when randomly distributed to respond to mechanical crimping in situ without forming 'such a boardy or stiff structure or being damaged excessively, it is necessary that these fibers be only partially drawn in a uniform and controlled manner. At the same time it has been found that excessively low levels of drawing, as determined empirically or measured by any convenient means such as average fiber X-ray orientation resulted in unacceptable mechanically crimped nonwoven structures; for example, in working with fibers formed of polyethylene terephthalate, X-ray total orientation angles greater than 60 are excessive. X-ray total orientation angles as used herein refer to the central angle sub-tended by the arc of an X-ray diffraction from half maximum intensity to half maximum intensity. The technique is described in a paper by H. G. Ingersoll, Journal of Applied Physics, vol. 17, page 924, 1946. In addition to this, it was found that variations in the draw level of individual fibers are indicated by any measure such as orientation of the individual fibers within the web must Such webs are characterized by an excessive be kept within reasonable limits. For example, in working with fibers of polyethylene tereplrthalate, optimum results were achieved only when X-ray total orientation angles were less than 60 and not less than 20 a coefficient of variation less than 20%. In addition, it was found that temperature conditions during crimping must be adjusted to promote set-ting which imparts stability in the final product. The desired crimp level and a dimensionally stable nonwoven web were achieved easily in working with polyethylene terephthalate when crystallinity was low in the raw web and when temperature conditions during crimping were sufficient to induce substantial crystallinity.

Crystallinity as used herein is determined by X-ray diffraction techniques. The X-ray diffraction pattern of the sample is prepared by standard film techniques, using a vacuum camera, and an equatorial densitometer scan (perpendicular to the longitudinal axis of the structure) of the pattern is made. Using polyethylene terephthal-ate as an example which is well known, the resulting curve exhibits three peaks, corresponding to the scattering from the 010, 110, and 100 diffraction planes, which represent the principal scattering from linear terephthalate polyester crystallites. For convenience in reporting results, an arbitrary subjective rating scale has been adopted in which zero crystallinity, a totally amorphous material, is rated as O, and the most crystalline sample recorded and known to the laboratory is rated as 9. Thereis thus a direct correlation with the more precise method of estimating percent crystallinity well known in the art.

Because of the differences between batch processing using fiat plates and continuous processing using calender type rolls, particularly with regard to time-temperature relationships, it has been found appropriate in working with polyethylene terephthalate to use a higher draw in the latter case and, hence, have greater orientation and crystallinity in the fibers of the webs before crimping. Such webs, if heated while unrestrained, shorten and narrow excessively and generally shrink in a manner difficult to control. This shrinkage is minimized by preventing heating of the web while unrestrained. This, referring again to FIGURE 3, is accomplished by cooling lips 45 and 48 which are installed at the respective entries of mechanical crimping device 21 and bonding and embossing device 28. I

Alternatively, and preferably, the minimization of shrinkage of the web, which also is termed stabilization, may be accomplished in a continuous manner by routing web 15, as it leaves roll 19, to felt calender 51 as is shown in solid lines in FIGURE 3. Prior to entering felt calender 51, web 15 is interleaved between cotton belts 52 and 53 which may be fabricated from a 72 x 72 greige cloth and move in the direction of the arrows. Web 15, so interleaved, is then'carried between the surfaces of felt belt 54 and heated can, or cylinder 55, which move in the direction of the arrows. Felt belt 54 passes endlessly about rolls S6, 57, 58, 59, 60, and 62 and by tensioning means not shown is maintained in intimate contact under controlled pressure with can 55, Roll 60 is appropriately cooled by means not shown to prevent overheating of felt belt 54. Cotton belt 52 passes endlessly about rolls 63, 56, 57, 64, 65, 66, and 67 and is tensioned against can 55 by means not shown. Cotton belt 53 passes endlessly about rolls 68, 56, and 57 and is tensioned against can 55 by means not shown. As with other devices of the schematic of FIGURE 3, driving means are not shown.

After stabilization in felt cylinder 51, web 15 is directed over roll 20' to mechanical crimping device 21 and proceeds as previously described except that cooling lips 45 tendency to form weak fiber to fiber bonds under pressure during crimping are minimized as well as is any predisposition to mechanical damage under the action of the pegs.

Furthermore, there have been found relationships between the pitch P of the crimping surface, the groove depth D of the crimping surface, and the maximum nonwoven web weight Wmax, for each stiffness level of product. These relationships are set forth in the following formulae:

1 DEJP 2 DEcP-t-d max.

where D=depth in inches, P=pitch in inches, W =basis weight in oz./yd. and, where a, b, c, and d are constants, which must be determined experimentally and result from the physical properties of, the fibrous elements employed and the ambient processing conditions.

In Table I are shown numerical values of constants a, b, c, and d for processing polyethylene terephthalate fibrous elements according to the process of this invention.

terephthalate, using a crimping surface having pegs, or protuberances, spaced uniformly 12 to the inch (12 x 12) with a depth of about 0.045 inch, the upper limits of fabric weight having vibration moduli of 600, 1000, 1500, 2000, and 3000 p.s.i., respectively, were established at approximately 2.5, 3.2, 3.5, 4.1, and 4.9 oz./yd. respectively.

It has been found that the relationships of Formulae 1, 2, and 3 are limited by the effect of increasing basis weight of the finished web structure of polyethylene terephthalate to values below 6 /2 ounces per square yard. Above 6 /2 ounces per square yard all patterns of the mechanical crimping means immaterial of pitch and depth produce structures with vibration moduli greater than about 10,000 p.s.i. at which level the structure may well be considered akin to paper while structures below a vibration modulus of 3,000 p.s.i. are akin to fabric, there being a transition zone therebetween.

Work with fibrous elements of synthetic organic materials other than polyethylene terephthalate has shown that the process of the instant invention is applicable. However, as workers in the field well know, the appropriate conditions for each particular material must be separately determined. Furthermore the measures of the conditions of one fiber may not apply to that of another. As an example, the invention was found to apply to polypropylene but X-ray data did not appear to be helpful in measuring the amount of partial drawing required or the proper level of heating needed to set the crimp. These conditions however were amenable to experimental determination. Thus, the invention is not to be characterized by a general measure.

The following examples illustrate specific embodiments of this invention that are not intended to be limiting and examples are given of the effect of working outside the invention.

Example 1 In accordance with the method of Kinney, elsewhere described and using the web spinning arrangement schematically shown in FIGURE 3, nonwoven sheets were prepared comprising 92% polyethylene terephthalate and 8% of a binder fibrous element comprising an 80/20 mixture of a copolyester of ethylene glycol with terephthalic and isophthalic acid. Corona charging and draw jet conditions were adjusted 'so that the fibers of this web were partially drawn and distributed in random nonparallel arrangement. The raw web so prepared was subjected to mild consolidation by pressing it at 50 C. for 5-10 seconds under a pressure of 200 p.s.i. A hand sheet cut from this web was mechanically crimped by being pressed between a -inch thick flat metal plate having 12 pyramidal protuberances per lineal inch, hence nominally designated a 12 x 12 plate, yielding a pitch of 83.5 mils, and having a depth of 80 mls, and an elastomeric sheet in a platen press heated to a temperature of 125 C., at a loading of 400 p.s.i., and held there for 180 seconds, during which period the actual sheet temperature was raised from room temperature to 95 C. The hand sheet was then subjected to a second mechanical crimping step, having been turned over on the same, already heated plate, using the same conditions of temperature, time,- and pressure as used in the first step. The hand sheet was then bonded and embossed using a 70 x 70 mesh Wire screen on one side and a 30 x 30 mesh wire screen on the other side, and employing a platen press heated to 220 C. at a pressure of 100 p.s.i. for 60 seconds, during which time the actual sheet temperature rose to 215 C. Fiber properties are shown in Table II-A. The resultant fabric structure was strong, highly uniform, and had soft hand and excellent drape. The physical and drape properties of the fabric are shown in Table II-B.

TABLE II-A (FIBER PROPERTIES) Raw Consoli- After After After Web 1 dated Crimp Crimp Bond Web #1 #2 Embossing Denier 2. 01 2. 62 1. 97 2.05 2. 21 Stand. tlev 0. 41 0.35 0.15 0. 26 0.31 Tenacity (g.p.(l.) 2.70 2. 99 3. 40 3. 06 3. 26 Elongation (percent) 172 163 62 56 31 Modulus (g.p.d.) 17. 3 17.3 26. 1 27. 45. 2 Work to break 2. 33 2. 55 1. 34 1.08 0. 69 Density 1. 3412 1. 3416 1. 3675 1. 3056 1. 3880 X-Ray results Crystallinity Rating 2 near 0 near 0 4 4 6 Orientation 60 gTgypical birefringence measurement for a web of this type at this stage is 0 2 Crystallinity rating eale: Totally amorphous=0; Maximum crystallinity recorded=9.

TABLE II-B (FABRIC PROPERTIES) Example 2 A web was prepared as in Example 1 but, to illustrate the harmful effect of too little drawing and cover conditions outside the range of the invention, with the processing conditions adjusted to provide less draw, and this web was consolidated, mechanically crimped, and bondembossed according to the process of Example 1. The resulting product was of poor quality and the web showed poor processing behavior characterized by. sticking to the plate with the result that the operator inadvertently enlarged the area 14% in removing the web. In addition, the product showed poor strength and harsh hand. The physical properties of the fibers and the fabric are shown in Table III-A and Table III-B, respectively.

1 1 TABLE III-A (FIBER PROPERTIES) Consoli- After After After dated Crimp Crimp Bond Web #1 #2 Ernbossing Denier. 3.01 2. 51- 2 38 Stand. dev .48 .48 Tenacity (g p d 2. 86 2. 37 2. 28 Elongation (percent) 149 66 Modulus, Mi 12.8 26. 23.0 Work to break. 2. 0. 91 0. 69 Density 1. 3401 1.3596 1. 37 4 X- Ray results:

Crystallinity 0 Orientation. 60 40-e0 -35 -40 Birefringence 0. 017

TABLE III-B (FABRIC PROPERTIES) Fabric weight, oz./yd. 2.2 Thickness, mils 12.4 Tensile strength, lb./in./oz./yd. 7.0 Elongation at 9 lb./in., percent 29 Elongation to break, percent Tongue tear strength, lb./oz./yd. 0.8 Vibration modulus, p.s.i. 1000 Fabric quality Poor Example 3.

A web was prepared as .in Example 1, but with processing conditions adjusted to provide greater draw. This web was consolidated, and mechanically crimped and bond-embossed according to the process of Example 1. The fiber and fabric properties are shown in Table IVA and Table IVB, respectively.

TABLE IVA (FIBER PROPERTIES) Example 4 A web was prepared as in Example 3, but with processing conditions adjusted to provide somewhat less dnaw. This web was consolidated by passing the sheet through a nip roll at a loading of 10 pounds per linear inch at a temperature of about C. The consolidated web was characterized by a high fiber shrinkage of 45-55%. The consolidated web was then crimped continuously by being passed at 4 yards per minute through cooling lips into the nip of a calender roll of approximately 12 /2 inch diameter and a back-up roll of similar size covered with an elas-tomeric cover comprising a 100 mil thick sheet of Viton of about durometer hardness. The calender roll had a surface machined in a manner according to FIGURES 5 and 6 of this specification, the pitch spacing being 0.0827 inch and the depth from peak to root being approximately 0.0815 inch. The flanks of the protuberances or teeth were tapered at about 5 normal to the roll axis, the peaks of the protuberances were formed by an are having a radius of 0.022 inch and the roots formed by an are having a radius of 0.015 inch. The calender roll and the back-up roll were internally heated by electricity to a temperature of 125 C. and were loaded to 400 p.s.i. based on the observed deflection area divided by the total .measured load. ,This load caused about 50 I mils of the peg depth to be used. The web was turned over and crimped a second time under the same conditions and then the web was rolled up.

Hand sheets, 10" X 12", were cut off this continuously mechanically crimped roll of web. They were then bonded and embossed between -mesh wire screen on one side and 30-mesh screen on the other side in a platen press using the conditions of 220 C. and p.s.i. for 90 seconds. Some of the hand sheets were subsequently machine-Washed and tumble dried in order to further improve their aesthetics and drape quality. The properties of the fibers in the web and the fabric properties are shown in Table V-A and Table V-B, respectively.

Consoli- After After After Raw dated Crimp Crimp Bond 40 TABLE (FIBER PROPERTIES) Web Web #1 #2 Ernbossmg Raw Web Consolidated Web Denier 2. 17 2.15 2.12 Stand.tdev.. d 0.21 Den e 1 1 Tenaci y ,5 Elongatiofl egercent) Standard deviation" 17 Modulus, Mi- T ty (g-D- 2,97 Work to brca Elong 111 Density Modulus (go- 1.) 19,1 X-Ray results: Work to break 1; 97 Crystallinity e y 1. 3498 Rating 3 4 6 ld p 0. c4 Orientation 2025 2025 2530 20-25 25-30" r0 X-Ray crystalhnity Iflt111g 0 2 Birefringence 0.071 0. 054 0.104 0.117 0 X-Ray orientation angle 50 30 TABLE V-B (FABRIC PROPERTIES Before Washing After Washing Machine Transverse Machine Transverse Direction Direction Direction Direction Fabric weight (0z./yd. 2. 47 2. 53 2. 50 2. 71 Thickness (mils) 13. 9 13. 1 13. 5 14. 0 Tensile strength (lb/in. per

oz./yd.=) 8. 9 7. 9 9. 1 6. 7 9 lb./in. elongation (1%) 1G 30 19 33 Break elongation (1%) 48 68 53 G4 Tongue tear strength (lb [02 yd. 0.73 1.0 1.2 1.4 Vibration modulus (p.s 1, 020 560 480 590 Quality Excellent Excellent Example 5 TABLE IV-B (FABRIC PROPERTIES) Fabric quality A web was prepared as in Example 4 but after consolidation and prior to mechanical crimping, the web was interleaved between cotton sheets and given one pass through a felt calender at C. The time in the calender was 40 seconds, some additional samples having been run as controls to determine a minimum process time of 20 seconds below which adequate stabilization did not Good 75 occur. Continuous crimping was performed as in the pre- TABLE VI Machine Transverse Direction Direction Basis weight, oz./yd. 2.1 2. 3 Tensile strength, lb./in./yd 10. 1 10.5 Break elongation, percent 58 47 Tongue tear strength, lb./oz./yd. 1. 8 2.0 Vibration modulus, p.s.i 750 520 Quality Erce|llent Attempts to lower the speed in crimping produced stiffer fabrics while increasing the speed reduced the crimp level. Similarly, higher temperatures produced stiffer, less acceptable fabrics.

Example 6 A web was prepared according to the method of Example 1 but with conditions adjusted to obtain a maximum draw. Note that this is outside the range of the invention. The fibers were spun with a ribbon-like cross section and where highly drawn having an X-ray orien tation angle of 15. 8 x 8 hand sheets were cut from this web after consolidation. These were subjected to mechanical crimping. At 625 p.s.i. loading the fibers were observed to be broken at the groove edges and did not conform to the 1135 8 of the crimping plate. Successive trials were made reducing the crimping pressure to determine the highest loading at which breaking would not occur. This was found to be about 300 p.s.i., with other conditions according to Example 1 and here it was observed that no appreciable crimp appeared.

Example 7 A web, prepared as in Example 1 was mechanically crimped by pressing between a inch square honeycomb plate and an intermeshing crimping plate containing 8 squareafaced pegs per lineal inch at 150 C. and 200 p.s.i. for 2 minutes. The thus mechanically crimped fabric was then bonded and embossed between wire screens at 220 C. and 50 p.s.i. for 60 seconds, so that the domes were compressed. In this process, the fibers tookon random, high amplitude, low frequency crimp. Similar results were obtained by replacing the honeycomb plate with an elastomeric sheet. The resulting fabric was soft, strong, and highly drapable.

Example 8 A Web was prepared as in Example 4 but with cospun binder fibers. This consolidated web was also characterized by a high fiber shrinkage. A hand-sheet cut from the web was mechanically crimped, embossed, and bonded in one operation by pressing it between a %-inch thick crimping plate having 60 parallel grooves per inch and a silicone rubber sheet. Both crimping plate and :fabric and rubber sheet were initially at room temperature but were placed in a platen press, preheated to 200 C. and held therein for 2 minutes under a pressure of 630 p.s.i. Pressure was released, the sheet turned 90 relative to the direction of the grooves in the crimping plate, and the pressing operation was repeated. The resulting structure acquired a square weave-like pattern and the structure was characterized by being stretchable. Upon hand stretching, drapable nonwoven fabric was obtained.

Example 9 A web was prepared as in Example 4 but differing in that no binder fiber at all was contained. A hand-sheet cut from the web was placed between a /4-inch thick crimping plate having a pegged lpattern spaced 50 x 50 to the inch, and a silicone rubber sheet, all being initially at room temperature.

The assembly was placed in a flat press preheated to 270, and held there for 2 minutes under a pressure of 500 p.s.i. down, and the pressing step repeated. The fabric resulting from this operation was found to be bonded and stretchable. Upon light stretching in both directions by hand, a drapable fabric was obtained having the following properties: Fabric weight, 1.5 oz./sq. yd.; tensile 5.2 lb./in./oz./sq. yd; elongation at break, 26%; tongue tear strength, 1.12 lb./oz./ sq. yd.; and vibration modulus, less than 200 p.s.i.

' Example 10 A web was prepared as in Example 5 but after mechanicrimpin-g and prior to embossing and bonding, the "continuous web was pressed in steps momentarily in a platen press between a soft (-50 Durometer hardness) 130 mil thick rubber sheet and an 8 x 8 mesh wire-screen at room temperature (20 C.) with 200 p.s.i., then the web was turned over and pressed a second time under the same conditions. This process mechanically worked the Web by opening and loosening up fragments which were highly compacted by the preceding mechanical crimping; As a result, the web became more bulky and softer without significant loss of crimp.

The continuous web was then embossed by pressing it in steps between two 30 x 30 mesh wire screens each backed up by a 62-mil silicone rubber sheet in a platen press at 170 C., 10 psi. for 6 seconds. As a result, the web obtained a uniform screen-like pattern on both sides.

Finally, the continuous web, being supported by a leader fabric, was passed through hot air at 225 C. in a pin tenter. The time in the pin tenter was 60 seconds. As a result the web hand become a bonded fabric, the properties of which are exhibited in the table below.

TABLE vn Machine Direction Transverse Direction Basis weight, oz./yd. 3. 4 3. 4 Tens'le strength, lb./in./oz./yd 12.0 7 0 Brea'r elongation, pereent 57 59 Tongue tear, 1b./oz./yd. 3. 1 3. 6 Extensometer modulus, p.s.i. 17, 860 7, 160

Quality l Extensometer morluli byond 3,000are excessively stilt.

Example 11 cally crimped sample was observed to have developed a level of the control.

Example 12 A web was prepared according to Example 1 except that linear poly(propylene) was co-spun with 17% poly- (ethylene) and conditions were adjusted to provide between 25 and 30% of normal draw, e.g., about a 2X draw. The raw web was consolidated flat between two sheets of rubber at C., 400 p.s.i., for one minute. Hand sheets cut from this web were mechanically crimped with a plate grooved 30 x 30 to the inch against rubber once on each side at 90 C. and 400 p.s.i., for one minute. A hand sheet was then bonded and embossed at C. and 400 p.s.i., between 40-mesh screens for two minutes. Properties of this web were as follows in Table VIII.

Pressure was released, the web turned upside TABLE VI-II Weight, oz./sq. yd. 2.0 Tenacity, lb./in./oz./yd. 5.9 Break elongation, percent 97 M lb./in./ oz./yd. 11 Tongue tear,1b./in./oz./yd. 3.5 Bending length, cm. 3.4

Example 13 A web was prepared according to the method of Example 12 except that 100% linear poly(propylene) was spun. The raw web was consolidated fiat between two sheets of rubber at 130 C., 300 p.s.i., for one minute. Hand-sheets cut from this web were dipped in 4.3% solution of Vistanex L-100 in xylene and dried to give 9% pick-up. These were then mechanically crimped once on each side with 30 x 30 grooves per inch plate against rubber at 130 C., 600 p.s.i., for 30 seconds. Samples were then flexed over a blunt edge to soften by mechanical working. Properties are given in Table IX following.

TABLE IX Weight, oz./sq. yd. 2.7 Tenacity, lb./in./oz./yd. 8.3 Break elongation, percent 150 M lb./in./oz./yd. 7 Tongue tear, lb./in./oz./yd. 3.1 Bending length, cm. 3.1

A control web on the above example, e.g., not mechanically crimped, would have a tensile strength between 8 and lb./in./oz./yd. and a bending length of 5 cm. Thus, the mechanical crimping gives the desired more flexible structure as shown by the lower bending length. Such a control web would have a' vibrational modulus running around 15,000 while the vibration modulus of the above example would approximate 4,000 and that of preceding Example 12, about 2,000. X-ray data on the polypropylene examples indicate that the raw webs have X-ray orientation angles between and and crystallinity indices of 5 to 8 before mechanical crimping, with very little change taking place in these parameters as a result of the crimping operation.

Example 14 l A two denier per filament tow of poly (ethylene terephthalate) is prepared according to standard commercial practice except that the draw ratio during the washing and drawing step is reduced so that only a partial draw is accomplished. After partial drawing, the tow is not crimped, but dried and cut into staple length fibers approximating inch long. These are blended 80/20 with fibrids ofpolyester prepared according to teachings of Example 142 of copending application S.N. 788,371, now US. Patent No. 2,999,788, and water-laid on a screen to prepare a waterleaf of randomly arranged fibers as further taught in that example. mechanically crimped, bonded andembossed as in Example 1 to produce a soft, drapable, nonwoven fabric having crimped fibers between bond points and exhibiting good properties. Similarly, a tow of partially drawn poly(ethylene terephthalate) is cut into 1-inch long staple and blended with 10% of l-inch staple fibers cut from an 80/20 mixture of poly(ethylene terephthalate)/poly- (ethylene isophthalate). Both Garnett carding and -Rando-'webbing techniques are used to prepare webs which are crimped, bonded, and embossed as before to producesatisfactory soft, drapable, nonwoven structures.

Example 15 The waterleaf is specifications and examples, the process has also revealed a surprising result in making the physical properties of the crimped fibers within a given web more uniform as well as making the properties of initially different webs more uniform in the crimped in situ state. This result is shown in Table X.

TABLE X EFFECT OF PROCESS ON PROPERTIES Initial Web After Property Web Identification Web Two Crimpings Denier (1) E74-5-NP1069-64 #13.. 2. 79 2. 52 (2) E745NP1069-64 #l6.- 2. 98 2.03 (3) EGO-5 2.17 2. 12 (4) 212-T 1. 51 1. 44 (5) 1l/16/1YZ-..- 1. 50 1. 30 (6) 1574-25-5 2. 2. 09 (7) 11/16/3-YZ 2.04 1. 22

Arithmetic Mean... 2. 26 1.81 Standard Deviation. 58 .46 Percent Coefiicient 26 25 of Variation.

Denier Standard (1) E74-5-NP1069-64 #13-. 0. 45 0.20 Deviation. (2) E74-5-NP1069-64 #16 0.20 0.17 (3) E60-5 0.13 0.21 (4) 212-T 0.17 0.21 (5) 11/16/1-YZ. 0.15 0. 09 (6) 1274-25-5"--. 0.41 0.31 (7) 11/16/3YZ--. 0. 36 0. 08

Arithmetic Mean.. 27 19 Standard Deviation. 13 .08 Percent Coefiieient 48 42 of Variation.

Tenacity, g.p.d... (1) E-74-5-NP1069-64 #13. 2.87 2. 90 (2) E745NP106964 #16- 2. 55 3. 04 (3) ESQ-5 3. l0 2. (4) 212-1 2. 97 23 (5) 11/16/1-YZ 3. 28 3. 24 E74-25-5 2. 55 3. 06 (7) 11/16/3-YZ 2. 87 3. 33

Arithmetic Mean... 2. 3. 09 Standard Deviation. 23 17 Percent Coefficient 8 6 of Variation.

Elon ation, per- (1) E745NP106964 #13 161 50 cent. (2) E74-5-NP1069-64 #16-- 149 (3) E-60-5.-- 111 60 111 45 Z. 107 54 (6) E74-25-5. 142 53 (7) 11/l6/3-YZ 108 51 Arithmetic Mean. 127 57 Standard Deviation- 21 12 Percent Coeflicient 17 21 of Variation.

.Modulus, Mi (l) E74-5-NP1069-64 #13-. 17. 9 26. O (2) E745NP106964 #16.. 17 0 23. 6 (3) EGO-5 32. 8 25. 2 4 19. 1 24.0 22. 1 23.0 15.9 24. 6 20. 8 28. 0

Arithmetic Mean 20.8 24. 9 Standard Deviation. 5. 3 1. 6 Percent Coefiicient 25 6 of Variation.

Work to Break... (1) ,E74-5-NP1069-64 #13-. 2. 36 0.80 (2) E745NP1069-64.#16-. 1. 90 1. 39 (3) E-60-5 2.00 1. 14 (4) 212-1 1. 79 1.00 (5) 11/16/1-YZ 2. 00 1.17 (6) 1374-25-5 1. 86 1.03 (7) 11/16/3-YZ 1. 71 1. 15

Arithmetic Mean. 1. 1. 11 Standard Deviation. 20 11 Percent Coefilcient 10 10 of Variation.

In the drawings and specification, there has been set forth preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purpose of limitation. The scope of the invention is defined in the claims.

I claim:

1. A process for producing an improved non-Woven structure having a high degree of drapability and soft ness of hand suitable for textile fabric uses, said process comprising in combination, the steps of arranging a plurality of partially drawn fibrous elements, capable of sustaining further drawing, in a random, non-parallel arrangement to form a web, subjecting the web at least one time to compressive and shearing forces in a multiplicity of areas substantially evenly distributed over at least one of the surfaces of the web by contact of said Web in a direction substantially normal to the planar axis of said web with spaced, individual protuberating elements having a frequency of occurrence of at least about 10 per linear inch, the said protuberating elements being under pressure, the forces controlled in magnitude, direction and points of application so as to crimp and further locally draw the individual fibrous elements to a macrocrimp level of at least about 10 crimps per inch, and simultaneously heating the web uniformly to a sufiicient degree to facilitate the crimping action and set the fibrous elements in the crimped configurations.

2. The process of claim 1 in which the high level of crimp is indicated by a macrocrimp having from about 10 to about 100 crimps per inch with a microcrimp supercrimped thereon and having at least 130 crimps per inch.

3. The process of claim 2 in which the crimped configurations of the macrocrimp have a gross displacement transverse to the fiber axis of from 0.003 inch to 0.125 inch.

4. The process of claim 1 which further comprises arranging a suitable binder material in substantially evenly interspersed relation with said plurality of fibrous elements during formation of said web, and, subsequently to said step of setting said fibrous elements subjecting the web of crimped set fibrous elements to a treatment which bonds said elements together at a plurality of distributed points through the web.

5. The process of claim 4 in which the fibrous elements comprise continuous filaments of a synthetic polymeric composition.

6. The process of claim 5 in which said filaments of a linear polyester composition.

7. The process of claim 6 in which said linear polyester composition is poly(ethylene terephthalate).

8. The process of claim 7 in which the partially drawn fibrous elements before crimping have been drawn to an extent indicated by X-ray total orientation angles less than about 60 and greater than about 20 and exhibit a crystallinity rating of between about 0 and 4.

9. The process of claim 4 which further comprises subjecting predetermined portions of said web to distorting force-s sufficient to permanently indent said web at said predetermined portions whereby embossing of said web is efiected.

10. The process of claim 1 which further comprises introducing into said web a binder material, and then subsequent to the steps set forth in claim 1 heating said web to activate said binding material whereby bonding of are - said web is effected.

11. The process of claim 10 in which said fibrous elements comprise continuous filaments of synthetic polymeric composition.

12. The process of claim 11 which further comprises subjecting predetermined portions of said web to dis-' torting forces sufiicient to permanently indent said web at said predetermined portions whereby embossing of said web is eifected.

References Cited by the Examiner UNITED STATES PATENTS 2,036,838 4/1936 Taylor 57-34 2,216,142 10/ 1940 Taylor et a1. 2872 2,430,868 11/1947 Francis 15634 2,457,784 12/1948 Slayter 156376 2,856,323 10/1958 Gordon 161-165 X 2,874,446 2/1959 Sellers 2872 2,917,806 12/1959 Spence et al 264-168 X 2,953,187 9/1960 Francis 156-376 3,025,202 3/1962 Morgan et a1. 15634 3,040,412 6/ 1962 Russell 2872 3,050,821 8/1962 Kilian 264168 3,093,444 6/1963 Martin 264168 OTHER REFERENCES Polyesters and Their Applications, Bjorksten Research Laboratories, Inc., Reinhold Publishing Corp, New York (1956).

1 References Cited by the Applicant UNITED STATES PATENTS 2,464,301 3/1959 Francis.

' FOREIGN PATENTS 816,004 7/1959 Great Britain.

EARL M. BERGERT, Primary Examiner. DONALD W. PARKER, Examiner.

R. R. MACKEY, P. R. WYLIE, J. MATHEWS,

Assistant Examiners.

Claims (2)

1. A PROCESS FOR PRODUCING AN IMPROVED NON-WOVEN STRUCTURE HAVING A HIGH DEGREE OF DRAPABLILITY AND SOFTNESS OF HAND SUITABLE FOR TEXTILE FABRIC USES, SAID PROCESS COMPRISING IN COMBINATION, THE STEPS OF ARRANGING A PLURALITY OF PARTIALLY DRAWN FIBROUS ELEMENTS, CAPABLE OF SUSTAINING FURTHER DRAWING IN A RANDOM, NON-PARALLEL ARRANGEMENT TO FORM A WEB, SUBJECTING THE WEB AT LEAST ONE TIME TO COMPRESSIVE AND SHEARING FORCES IN A MULTIPLICITY OF AREAS SUBSTANTIALLY EVENLY DISTRIBUTED OVER AT LEAST ONE OF THE SURFACES OF THE WEB BY CONTACT OF SAID WEB IN A DIRECTION SUBSTANTIALLY NORMAL TO THE PLANAR AXIS OF SAID WEB WITH SPACED, INDIVIDUAL PROTUBERATING ELEMENTS HAVING A FREQUENCY OF OCCURRENCE OF AT LEAST ABOUT 10 PER LINEAR INCH, THE SAID PROTUBERATING ELEMENTS BEING UNDER PRESSURE, THE FORCES CONTROLLED IN MAGNITUDE, DIRECTION AND POINTS OF APPLICATION SO AS TO CRIMP AND FURTHER LOCALLY DRAW THE INDIVIDUAL FIBROUS ELEMENTS TO A MACROCRIMP LEVEL OF AT LEAST ABOUT 10 CRIMPS PER INCH, AND SIMULTANEOUSLY HEATING THE WEB UNIFORMLY TO A SUFFICIENT DEGREE OF FACILITATE THE CRIMPING ACTION AND SET THE FIRBROUS ELEMENT IN THE CRIMPED CONFIGURATIONS.

4. THE PROCESS OF CLAIM 1 WHICH FURTHER COMPRISES ARRANGING A SUITABLE BINDER MATERIAL IN SUBSTANTIALLY EVENLY INTERSPERSED RELATION WITH SAID PLURALITY OF FIBROUS ELEMENTS DURING FORMATION OF SAID WEB, AND, SUBSEQUENTLY TO SAID STEP OF SETTING SAID FIRBROUS ELEMENTS SUBJECTING THE WEB OF CRIMPED SET FIBROUS ELEMENTS TO A TREATMENT WHICH BONDS SAID ELEMENTS TOGETHER AT A PLURALITY OF DISTRIBUTED POINTS THROUGH THE WEB.

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