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Publication numberUS3117056 A
Publication typeGrant
Publication dateJan 7, 1964
Filing dateMay 9, 1960
Priority dateMay 9, 1960
Also published asDE1435114A1, DE1435114C3
Publication numberUS 3117056 A, US 3117056A, US-A-3117056, US3117056 A, US3117056A
InventorsKatz Manfred, Maansi Munzer
Original AssigneeDu Pont
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Conformable bulkable non-woven web
US 3117056 A
Abstract  available in
Images(11)
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Claims  available in
Description  (OCR text may contain errors)

United States Patent 3,117,056 CQNFQRMABLE BULKABLE NflN-WQVEN WEB Manfred Kate and Manner Malransi, Wilmington, Deh, assignors to E. l. du Font de Nemours and (Ioinpany, Wilmington, Deh, a corporation of Delaware No Drawing. Filed May 9, 1950, Ser. No. 27,476 (Claims. (Cl. 151-170) This invention relates to fabrics and more specifically to novel non-woven fabrics prepared from synthetic organic polymer fibers.

Fabrics in general fall into two classes: woven and non-woven. Woven fabrics usually include knitted fabrics and may be defined as fabrics formed by the interlacing in a predetermined regular geometrical pattern of one or more long lengths of yarns or filaments. Non-woven fabrics, on the other hand, are usually formed by a random or controlled deposition of filamentary strands to form a sheet or batt followed by binding these strands in some way to provide strength and dimensional stability.

Although each type of fabric has advantages for applications in specific areas, there are certain fundamental property differences which have hitherto been considered as inescapable adjuncts of the method by which the fabric was formed. Woven and knitted fabrics have generally been recognized as stronger, more flexible, more readily prepared in light weights, and more drapable. Nonwoven fabrics, such as felts, have, for the most part, been confined to applications such as hats, filter cloths, and so on, because of the ease with which they can be formed into a dense material of low porosity and also because of the low cost of preparing the finished fabric structure directly from the individual fibers.

The advantage of low processing cost is one of the very desirable features of non-woven fabrics. All of the various processing steps which are required in the preparation of woven and knitted fabrics add considerably to the cost of the final product. Thus, in the formation of a woolen suiting material, the wool fibers must be formed into a yarn, the yarn must be twisted or plied, and the resulting final yarn product must then be woven into a fabric. It would be extremely desirable to provide a process which would involve simple well-known papermaking procedures but would produce a textile fabric having the properties of a woven fabric.

Although low cost and certain property advantages of non-woven fabrics have led to the employment of these materials in a number of specific end uses, limitations which have hitherto been considered a necessary part of the non-woven structure have eliminated them from many apparel applications. Womens skirts are occasionally made from certain non-woven felts, but in general these have enjoyed very limited appeal. It has been found practical to make womens dresses, mens and womens suitings, coatings, sweaters, and the like from non-woven fabrics, one of the major reasons being that non-woven fabrics have heretofore been rather stiff and bulky and, therefore, possessed poor drapability.

Non-woven fabrics could find extended utility if ways could be found to alter their dimensions and thickness after formation in a controllable and permanent manner. Fabrics having such properties would permit the manufacture of apparel which could be shaped or molded to the body of the user. Moreover, if the thickness dimension of such fabrics could be increased without shrinkage of the lateral dimensions even greater versatility would be afforded the fabric. Furthermore, if fabrics of such a conformable and bulkable nature were available, they could be employed in many non-apparel uses such as upholstery, home furninshings, and even many industrial uses as fabric-covering materials for rigid three-dimen- Patented Jan. 7, lllfid "ice sional articles, where the conformability would avoid or at least reduce the need to fold, pleat, tuck and otherwise shape an essentially fiat material in conformity with a three-dimensional curved surface.

Some fabrics, such as wool, can be made to retract under certain conditions. Woolen clothes, for example, are shaped into conformity with the human body with the use of steam irons, etc., but this shapeability is of very limited nature. Furthermore, the change in dimension is in one direction only; that is, the fabric can be shrunk but they cannot be caused to expand to any appreciable extent. Shrinkable synthetic fibers are also known, but up to now there has not been available any non-Woven synthetic fabric which was extensible, bu kable, and conformable.

It is an object of this invention to provide non-woven synthetic fabrics which exhibit a combination of flexibility, strength and a conformable, bulkable, extensible nature in response to simple thermal treatment, thereby affording fabrics which can be shaped as desired to conform to three-dimensional contours. It is also an object of this invention to provide a process for the production of these fabrics.

A further object is to provide a process for the production of non-woven bonded fabrics of synthetic fibers, which fabrics exhibit a combination of high tensile strength, conformance, bulk and high drape thereby affording aesthetic and physical properties comparable to those of woven or knitted textile fabrics of the same weight and fiber composition.

It is also an object of this invention to provide nonwoven fabrics of synthetic fibers by a novel process using conventional paper-making techniques and equipment.

The products of this invention are conformable, bulkable non-woven fabrics of synthetic fibers comprising at least 50% by Weight of synthetic organic spontaneously elongatable fibers, as defined in detail below, together with from 3% to 50% by weight of a synthetic organic polymer binder dispersed uniformly throughout the nonwoven web, said binder having a modulus between about 0.002 and about 25 grams per denier (g.p.d.). The nonwoven webs of this invention have the capacity upon heating to form a bonded non-woven fabric in which the fibers contain at least 30 crimps/ inch (c.p.i.) and in which the fibers are bonded at spaced points throughout the fabric such that the average total length of an individual fiber element between adjacent fiber bond points is at least 1.25 times the straight line distance between the same fiber bond points. The binder is present in an amount such that Percent biDLlGIXR ZMZ of binder l0 where the percent binder is based on the total weight of the fabric, including the binder. The modulus (Mi) of the binder is between about 0.002 and about 25 grams per denier.

in a preferred embodiment of this invention, nonwoven fabrics of synthetic organic fibers are formed by preparing a suspension of synthetic organic spontaneously elongatable staple fibers and a synthetic organic binder in water, the suspension containing less than about 10% solids by weight. By the term spontaneously elongate.- ble fibers is meant fibers which are capable of elongating spontaneously at least 3% upon heating at a tempera- .ture 30 C. above the second order transition temperature of the fibers for five minutes. A waterleaf is prepared from the slunry and dried at a temperature below that at which the fibers elongate spontaneously and also below the fusing temperature of the binder. The water leaf is then heated at a temperature sufficient to fuse the binder and also to elongate the fibers at least 3%, based on their original length, while restraining the fabric from increasing more than 3% in linear growth in any surface direction.

The individual filamentary components of preferred fabrics prepared by the process of this invention possess a high degree of lateral freedom and flexibility in three dimensions between intersection points and points of bonding, thereby providing these fabrics With a high degree of drape and softness, high tensile strength, low bulk and a soft handle in the same range as Woven fabrics. The fabrics are characterized by a fabric density of 0.28 to 0.6 g./cc., a drape stiffness of not over 1.0 inch, a ratio of tensile strength to drape stiffness of at least 12.0 lbs., and a sonic velocity-elongation differential of at least 1.3. They are, therefore, readily distinguished from papers on the one hand and conventional thick and bulky nonwoven felts on the other. The novel non-woven fabrics of this process of this invention are equivalent in handle, thickness drapability, strength and other aesthetic and physical properties to a wide spectrum of woven fabrics.

Waterleaves are prepared according to the conventional papermaking technique from a loose slurry or suspension of fibers and binder, usually containing less than about 5% solids and preferably less than about 1% solids in water. Of course, liquids other than water may be used so long as they are inert to the solids, but economy and convenience favor water as the liquid phase. Also, greater concentrations of solids may be employed, say up to or more, but the most useful sheets are obtained with 5% solids or less.

Spontaneously elongatable fibers are disclosed in Belgian Patent 566,145, granted September 27, 1958. Synthetic organic fibers may be prepared capable of elongating spontaneously up to 30% or more under the above stated conditions. Patricularly suitable for preparing spontaneously elongatable fibers are polyesters, such as polyethylene terephthalate, polyhexahydro p xylylene terephthalate, and similar polymers of monomers prepared by reacting terephthalic acid with ethylene glycol or similar glycols. Polyamides are also useful for this purpose, particularly poly(p-xylylene azelaeamide). In addition to these, other spontaneously elongatable fibers include those composed of polyurethanes, acrylonitrile polymer fi ers, and the like. Polyolefins such as polypropylene and other addition type polymers may also be used, but polyester fibers are the preferred spontaneously elongatable fibers used in this invention.

In addition to the spontaneously elongatable fiber and binder utilized in the process of this invention, minor amounts of other fibrous materials may also be employed although it is preferred that these be kept at a minimum in order to achieve the most desirable properties in the products produced. Thus, ordinary staple fibers of synthetic organic polymers such as any of the polyamides, polyesters, polyurethanes, acrylic fibers, and polyolefins mentioned above, and additionally cellulosic fibers such as rayon, cellulose acetate, and the like, may be used in minor amounts, preferably less than about by weight based upon the dry weight of the web produced. In addition, certain natural fibers, such as goat hair, can 'be used in amounts up to and preferably between 5% and 15 to give fabrics of high resiliency.

In addition, of course, certain non-fibrous materials may be added to an extent not greater than 10% by weight of the final dry web to obtain a wide variety of particular product advantages such as color, surface proper-ties, and the like.

Binders used in the process of this invention are synthetic organic polymers having an initial tensile modulus of between about 0.002 and about 25 grams per denier. Preferably, the binder is used in the form of a fibrid, which term designates a non-rigid, wholly synthetic polymeric particle capable of forming paper-like structures. Thus, to be designated a fibrid, a particle must possess an ability to form a waterleaf having a couched wet tenacity of at least about 0.002 gram per denier when a multitude of the said particles are deposited from a liquid suspension upon a screen, which waterleaf, when dried at a temperature below about 50 C., has a dry tenacity at least equal to its couched wet tenacity, and a capabilit when a multitude of the said particles are deposited concomitantly with staple fibers from a liquid suspension upon a screen, to bond a substantial weight of the said fibers by physical entwinement of the said particles with the said fibers to give a composite waterleaf with a wet tenacity of at least about 0.002 gram per denier. By a capability to bond a substantial weight of (staple) fibers is meant that at least 50% by weight of staple based on total staple and fibrids can be bonded from a concomitantly deposited mixture of staple and fibrids. In addition, fibrid particles have a Canadian freeness number between and 790 and a high absorptive capacity for water, retaining at least 2.0 grams of water per gram of particle under a compression load of about 39 grams per square centimeter. Any normally solid wholly synthetic polymeric material may be employed in the production of fibrids. By normally solid is meant that the material is non-fluid under normal room conditions.

It is believed that the fibrid characteristics recited above are a result of the combination of the morphology and non-rigid properties of the particle. The morphology is such that the particle is non-granular and has at least one dimension of very minor magnitude relative to its largest dimension, tie, the fibrid particle is fiber-like or film-like. Usually, in any mass of fibrids, the individual fibrid particles are not identical in shape and may include both fiber-like and film-like structures. The nonrigid characteristic of the fibrid, which renders it extremely supple in liquid suspension and which permits the physical entwinement described above, is presumably due to the presence of the minor dimension. Express ring this dimension in terms of denier, as determined in accordance with the fiber coarseness test described in Tappi 41, A7A, N0. 6 (June) 1958, fibrids have a denier no greater than about 15.

Complete dimensions and ranges of dimensions of such heterogeneous and odd-shaped structures are difficult to express. Even screening classifications are not always completely satisfactory to define limitations upon size since at times the individual particles become entangled with one another or wrap around the wire meshes of the screen and thereby fail to pass through the screen. Such behavior is encountered particularly in the case of fibrids made from soft (i.e., initial modulus below 0.9) polymers. As a general rule, however, fi'brid particles, when classified according to the Clark Classification Test (Tappi 33, 294-8, No. 6 [June] 1950) are retained to the extent of not over 10% on a IO-mesh screen, and retained to the extent of at least 90% on a ZOO-mesh screen.

Fibrid particles are usually frazzled, have a high specific surface area and, as indicated, a high absorptive capacity for water.

Preferred fibrids are those the waterleaves of which when dried fora period of twelve hours at a temperature below the stick temperature of the polymer from which they are made (i.e., the minimum temperature at which a sample of the polymer leaves a wet molten trail as it is stroked with a moderate pressure across the smooth surface of a heated block) have a tenacity of at least about 0.005 gram per denier.

Fibrid particles and their preparation are described in more detail in Belgian Patent 564,206. Fibrids can be prepared from a number of polymeric compositions, and a wide range of such fibrids can be used in the present invention, leading to a spectrum of fabrics as indicated above.

The web products of this invention contain between about 50% and about 97% spontaneous.y elongata'olc fiber and bet-ween about 3% to about 50% binder based on dry weight of the web. Other fibers may be present to provide special effects such as extra strength, dyeability, etc., in amounts up to 40% but preferably less than by weight of the web. Elastomeric binders useful in this invention (which are characterized by an initial modulus (Mi) of between about 0.002 and about 0.9) should be used whenever a binder content greater than about by weight is desired and then preferably in the form of fibrids. Binders having an initial modulus greater than 0.9 should be used in quantities of less than about 25% based on the dry Web weight. Obviously, the procedure used for preparing these webs may employ comparable quantities of fibers and binder since there is usually no appreciable loss of solids during the process.

In a preferred process of this invention, a waterleaf is prepared containing between 50% and 75% spontaneously elongatab-le staple fibers having a length of between and inch and from 25% to 50% elasto-meric fibrids. In this embodiment, less than about 15% of ordinary hard fibers (non-elongatable) should be present. Representative el astome-ric binders are the various butadiene-styrene copolymers containing from to 70% combined butadiene, and also terpolymers of but-adiene, styrene, and acrylonitrile. Other preferred el'astorneric binders include a mixture of 98% polyimethyl methacrylate plus 2% glycidyl methacrylate in the amount of 10 parts, and about 86 parts of an acrylate ester terpolymer; a mixture of 49 parts polyhexylmethacrylate, 49 parts polyethyl aorylate, and 2 parts polyacrylic acid prepared by solution polymerization, for example, in benzene using benzoyl peroxide as initiator; poly(ethylene/propylene) polymerized using 3% dicurnyl peroxide; a copolymer of an aliphatic ester of acrylic acid and up to 5% acrylic acid, such as, for example, a copolymer of 98% ethyl acrylate and 2% acrylic acid. Another useful eliastomeric binder is obtained by reacting poly(tetramethy1ene ether) glycol of approximately 1000 molecular Weight with tolylene 2,4-d iisocyanate to give a glycol-terminated macrointerrned-iate and this is treated to give an isocyanate-ended, low molecular weight polymer by combining the macrointerme-diate with methylene bis(4-pl1enylisocyanate). This low molecular weight polymer is then reacted further with hydrazine to give a high molecular weight elastomer polymer in accordance with the disclosure of French Patent 1,172,566.

Representative of non-elastomeric binders useful in this invention are polyamides such as polyhexamethy-lene adipamide, polycaproamide, copolyrners of polyhexa-rnethylene adipamide and polycaproamide (preferably an 80/20 coplymer, respectively), poly(hexahydro-p-xylylene teradipamide and the like. Representative polyesters useful as binders include polyethylene terephthalate, polyethylone isophthalate, copolymers of polyethylene terephthalate and polyethylene isophthalate (prefenably an 80/20 copolymer, respectively), poly(hexahydro-p-xylylene terephthalate) etc. Particularly useful polyurethane binders are the polyurethanes formed by reacting piper-azine and ethylene bis-chloroformate, the urethanes of polyhexamethylene adip-amide and ethylene bis-chlorofornrate, etc.

The preparation of non-woven materials from wholly synthetic sheet forming particles is described in some detail in Belgian Patent 564,206. For larger-scale operation, it is usually desirable to prepare non-woven materials by a continuous process using, for example, papermaking machinery such as the Fourdrinier machine and other comparable pieces of apparatus, as well as carding machines, Rando-Webber machines, and other equivalent devices. Webs containing spontaneously elongatable fibers in the form of continuous filaments can be pre pared by processes employing electrostatic phenomena to control the formation of the non-woven structure, as described in copending application S.N. 859,614, filed by Kinney on December 15, 1959 (RD658A), whereby the filaments, relaxed during or after web formation, are thereafter capable of spontaneous elongation upon heating.

Following preparation of a waterleaf of spontaneously elongatable fibers and binder in accordance with this invention, the waterleaf is dried at a temperature loW enough to avoid any fusing or melting of the binder or elongation of the fibers. Drying of the waterleaf at from C. to about C. is generally suitable for production of the novel webs of this invention. Drying in the range 100 C. to 120 C. is preferred.

After drying, the Web is then heated to elongate the fibers and fuse the binder to the fibers at their cross-over points While restraining the fabric from enlarging in surface area substantially. Sufiicient restraint should be applied to prevent more than 3 increase in linear growth of the fabric in any direction. This is preferably accomplished by pressing the dry web between two screens or similar foraminous members. During pressing, the fibers elongate and crimp in the thickness direction of the fabric, thereby giving additional bulk to the final product and providing a fabric-like hand both due to the bulk thus attained and due to the pattern thus embossed on the fabric by the screen or other foraminous member. Restraint may be applied by other means, however, such as pressing between two fiat or curved surfaces, whereby surface friction provides sufficient restraint. Equally well, a curved surface and a screen may be employed, as well as other techniques known in the art of shaping, vacuum forming, etc.

Elongation of the fibers in the web is usually achieved by heating the dry web at C. to 250 C. for a few minutes, usually less than 10 minutes. it is essential that some fusing (bonding of the fibers) of the binder occurs before all of the desired amount of elongation of the fibers is completed, and likewise it is essential that some elongation occurs before all of the desired amount of bonding is completed. Preferably, both elongation and bonding take place simultaneously, and this is easily achieved by choice of a suitable temperature dependent upon the compositions of binder and fibers. Usually, pressing the web at a temperature between 150 C. and 220 C. will suffice. Naturally, the precise degree of fusion and amount of elongation will depend upon the temperature and time of pressing and pressure used. Under extreme conditions of pressing when a fibrid binder is present, the fibrid particle identity is lost and the fibrids become fused completely into the non-woven structure.

In the production of the preferred non-woven fabrics already described, the embossing procedure offers a valua ble improvement in the woven-like characteristics which are desired. For example, when pressing between screens is employed, the self-elongatable fibers elongate and assume a third-dimensional configuration on the surface of the fabric, due to penetration of portions of the fibers into the interstices of the screen. Such configuration gives desirable bulk to the fabric. Similar response to other preferred embossing techniques is also possible, and such third-dimensional configurations make an important contribution to the suppleness and drapability of the products obtained thereby. In general, to obtain products of greatest interest, it is usually found that a moderate degree of pressing is most satisfactory.

Drapability is measured by determining the length of fabric which is necessary to cause the fabric to bend from the horizontal plane when under no constraint to such an extent as to contact a declining angle of 4l.5 of slope from the point of departure of contact. A strip of fabric one inch wide is placed upon a block of wood or other horizontal surface. Abutting the horizontal surface of this material is a 41.5 inclined plane, which at its top adjoins the horizontal surface. The test specimen is placed with the narrow edge at the juncture of the horizontal and the inclined surfaces. It is then moved forward over the inclined surface until the free end touches the 41.5 slope of the testing block. The drape stiffness, designated C, is measured in inches, being one-half of the free length of specimen extending beyond the horizontal sur- '5 face edge. An equivalent test, the cantilever test of ASTM Dl388-55T, gives values in the range of 50 to 2,000 mg.-cm., in measuring the stiffness of fabrics.

Bulk of a fabric is determined by cutting a square portion of the fabric of uniform thickness, measuring its dimensions, including its thickness, and then calculating its volume. The fabric sample is measured for thickness by means of a conventional fabric thickness caliper device such as an Ames gage (manufactured by B. C. Ames Company, Waltham, Mass). The fabric sample is then Weighed and the bulk expressed in terms of volume per unit weight.

Tensile strength is determined on a one-inch strip of fabric in conventional manner employing an lnstron Tensile Tester. For purposes of this invention, tensile streng'. is determined at room temperature under ambient conditions of 65% relative humidity. The ratio of tensile strength of a fabric to its drape-stiffness is useful for comparing the fabrics of this invention with conventional woven fabrics, felts, and papers.

Sonic velocity-elongation clifierential is a measurement of the effect of fabric elongation (and tension) on the velocity of sound transmission in the plane of the fabric. Measurement of sound velocity in fabrics is well known (see article "by W. H. Charch, W. W. Mosery in 29 Textile Research Journal, page 525 (1959)) and involves wel established principles and techniques. The velocity of propagation of sound waves in a fabric is dependent on fabric tension and is indicative of certain fabric properties. Woven fabrics, and also the non-woven fabrics of this invention, provide media through which sound travels at a velocity which is strongl dependent on the elongation (and the tension) in the fabric, indicating that both have very similar structural characteristics and properties despite their vastly different coarse structure (e.g., woven vs. non-woven). Other materials, such felts, papers, and leathers, transmit sound at a nearly constant velocity, that is, substantially independent of the degree of elongation of the structure.

Sonic velocity in a fabric can be measured using a piezoelectric crystal signal source (or other source) to provide vibrations of the desired frequency. Frequencies in the range of 1,069 to 40,000 c.p.s. are conveniently employed. As a detector, a search transducer (a piezoelectric crystal is again suitable) is used, placed at a fixed distance from the source. Pulse propagation timing or Wavelength measurement are suitably used to determine sonic velocity. For the purposes of measurements employed here, the source and detector can both be placed in contact with a fabric sample which is placed in the jaws of an 'Instron Tensile Tester or other elongation device. The sonic velocity is then measured as a function of elongation. Table 1 summarizes the data obtained.

TABLE I Velocity at Dificrent Elongations, kDL/SCG.

Sheet Material 3% 6% Ratio V0%/VO% Nylon paper 1. 1. 28 1. 31 1.05 Nylon woven fabric" 0. 46 0. 54 0. G2 1. 35 Non-woven (Ex. 2)-. 0.60 0. G9 0.79 1.32

It will be seen that the paper material, while having a high critical sonic velocity value, shows no substantial change as it is tensioned. On the other hand, the woven fabric and the non-woven fabrics of the present invention show a sonic velocity value which increases by at least 36% when the fabric is elongated 6%.

The preparation of non-woven materials from wholly synthetic sheet forming particles is described in some detail in Belgian Patent 564,206. in that p tent it is shown that polymeric materials may be prepared in the form of particles which have the property of interentungling with one another and with staple fiber materials to form strong sheet materials. Sucl sheets are advantageously prepared by deposition of the fibrid particles from an aqueous slurry onto a screen in laboratory operations. Watcrleaves or hand sheets may be prepared on a small scale by pouring a suitable amount of the slurry onto a small rectangular screen and draining the water down through the screen. Such hand-sheet Watrleaves are suitable for the practice of the present invention in that they permit a simple, small-scale preparation of non-woven structures which can then be tested for physical properties, strength, and the like. For larger-scale operations, it is usually desirable to prepare non-woven materials on a continuous process using, for example, papermaking mt chinery such as the Fourdrinier machine and other comarable pieces of apparatus, as well as carding machines, Rando-Webber machines, and other equivalent devices. it is well established in the papeirnaking industries, which base their operations on the use of beaten wood pulp and similar cellulosic materials, that laboratory hand-sheets are satisfactory as small-scale prototypes of the continuous products which can be prepared on small-scale papermaking machinery. In the examples below it is shown that both small-scale experimental units of nonwvoven fabrics can be prepared in accordance with the teachings of the present invention and that the same operations are applicable when continuous papermaking machinery or other sheet and web-forming devices are employed.

The non-woven fabrics of the process of this invention are characterized by a high degree of drapability and flexibility, and a desirable level of loftiness, and handle. Because of these and other properties, they are well suited to end uses which have heretofore employed woven fabrics of varying weights and weaves. Among such uses may be listed apparel; draperies; upholstery materials; house hold furnishings, such as table cloths, napkins, and bed linens; shaped articles, such as gloves, head coverings, brassiere cups; fabric stitfeners, such as interliners, peplums, cuff and collar liners, and the like. in the field of apparel fabrics, the fabrics of the present invention are specifically well suited to work and service clothing, sports wear, outer Wear, bathing suits, shirts, and the like. Other fabric utilities include foundations for leather-like laminates, backings for vinyl-coated upholstery, and other fabrics, automobile and airplane headliners (in this use the embossable nature of the non-woven fabrics of this invention is particularly desirable) filter cloths and other industrial felts. These fabrics are also suitable with proper coatings or surface treatment for use as fuel pump diaphragms, hosing flexible couplings, and air bellows for use in instrumentation work and decorative covers for desk equipment, radios, ash trays, cigarette boxes, and the like.

Because of the conformability and 'bulkability of the fabrics, as well as the thermoplastic nature of the fibrous materials employed in these products, it is possible and desirable to shape or form the sheet products of the present invention obtaining thereby articles possessing specific and desirable three-dimensional configurations. In general, it is preferred that when fibrid binders are used, the products of the present invention be heat-treated to a degree sufficient to fuse at least a portion of the fibrid binders. However, non-fused products are also of interest and have found applications in a number of the utilities indicated above.

As has already been indicated, the non-woven fabrics of the present invention are embossable and can be obtained with any of a Wide variety of surface patterns which may be impressed upon the fabric during the pressing or fusing process. Such embossed configurations not only supply decorative and attractive appearance, but can be used to control the physical properties of the fabric. Thus, an embossing pattern consisting of a number of parallel fine lines in one direction only produces a fabric which has a greater flexibility in one direction than in the other direction. Embossing with a crosshatched. type of pattern of fine lines increases the stiffness of the fabric in both directions. Other embossing techniques can be used to alter the handle and feel of the fabric and also to control the receptivity of the fabric to printing, dyeing, and other coloring post-treatments. During the embossing process the bulk of the non-woven fabric can be controlled to any desired degree, and compression can be introduced to lead to a more compact structure, if this is desired. Furthermore, it is not necessary that only a single embossing step be introduced. If desired, it is possible to emboss upon the non-woven fabric an over-all textured pattern by the use of wire screens as already shown. Thereafter, this fabric can be further modified by a second embossing treatment employing platens, calenders, intaglio rolls, or the like.

Fabrics of the present invention can be buffed to expose surfaces which are densely populated with uniformly distributed fiber ends of equal length. Such buffed surfaces are very attractive and resemble to a surprising degree in hand suede leather and other similar products.

The products obtained through the practice of the present invention have a number of advantages in comparison to previously known non-woven fabrics. In comparison with ordinary and conventional cotton or wool felts, the present materials show equal or higher strength, greater dimensional stability, and greater flexibility. In comparison with non-woven sheet products from ordinary synthetic fiber staple bonded with resin materials, the non-woven fabrics of the present invention have a much softer handle, greater strength and flexibility, and a better dyeability and printability. In addition, the fabrics of the present invention show an excellent degree of postformability, high elongation and liveliness, excellent washwear characteristics, outstanding tensile and stitch strength, and, as has already been indicated, a degree of drapability and controllable handle which has not hitherto been achieved in non-woven fabrics in the art.

Particularly desirable fabrics of the present invention are those prepared from formulations comprising at least 25% of a fibrid binder prepared from an elastorneric polymer, together with at least 50% of a spontaneously elongatable fiber material having, under the conditions described for determination of spontaneous elongation, an elongation of at least 10%.

Other useful embodiments of the present invention are drapable and flexible but somewhat more crisp and firm non-woven fabrics prepared from formulations comprising at least 75% of a spontaneously elongatable fiber having a minimum of 10% spontaneous elongation, together with a fibrid binder based upon a synthetic polyester polymer to the extent of at least 3 and not over by weight.

Any of the techniques which are known for the processing of conventional staple fibers in the preparation of non-woven fabrics can be used in the present invention. For example, it is sometimes desirable to prepare a layered type of structure by depositing upon the surface of the fabrics of this invention small amounts of additional fibrid binder, say in the order of 0.10 oz./sq. yd., in order to provide a firmer and more completely bonded surface. Deposition of the binder is followed by fusion, and sheets prepared in this way show an improved resistance to surface wearing, marring, fuzzing, pilling, and the like.

While several of the preferred embodiments of the present invention employ fairly short staple fibers, that is, A long or less, it is possible and at times desirable to use longer fibers, including staple fibers as long as three inches. Dispersion and deposition of such fibers into a sheet product are made easier by the use of foamdispersion processes or liquids of viscosity, rather than the water-dispersion processes described in connection with shorter fibers. Other web-forming processes may also be used. The use of longer fibers or continuous filaments increases the tensile strength and tear strength of the non-woven materials of this invention.

The following examples illustrate the invention. parts are by weight unless otherwise indicated.

EXAMPLE 1 Three parts self-elongatable polyethylene terephthalate staple fibers 0A" long, three denier per filament) prepared according to the process of Belgian Patent 566,145 and having a spontaneous elongation of 12%, are admixed by vibration stirring (using a Vibro Mixer) with 8000 parts of water. The fibers are pre-wetted with a small amount of a polyethylene oxide ether fatty alcohol as wetting agent. To this fiber suspension is added a slurry containing two parts of the synthetic elastomer fibrids in 5000 parts water prepared according to the procedure of French Patent 1,172,566 by reacting a poly- (tetramethylene ether) glycol of approximately 1,000 molecular weight with tolylene-2,4-diisocyanate to give a glycol-terminated macrointermediate. This is treated to give an isocyanate-ended, low molecular weight polymer by combining the macrointerniediate with methylene bis(4-phenylisocyanate). This low molecular weight polymer is then reacted further with hydrazine to give a high molecular weight elastorner polymer. This synthetic elastomer is soluble in dimethylformamide. A solution is p epared containing 12% synthetic elastomer solids and 4% polyvinylchloride solids in dimethylformamide. Fibrids are then prepared according to Belgian Patent 564,206 by placing 400 ml. of glycerol together with 0.5 ml. of an organic surfactant in a one quart Waring Blendor and adding the polymer solution while running the Blendor at full speed. The glycerol precipitates the polymer from solution, and the Waring Blendor subjects the precipitating polymer to high shear to give elastomeric fibrids. The washed fibrids are stirred for a few seconds in water to break up agglomerates, and the fibrids thus obtained are then maintained in water suspension ready for use. This stock is poured into a head box of a sheet mold, and a waterleaf is deposited onto an 8" by 8 MiG-mesh screen. The screen with the deposited water-leaf is removed from the sheet mold and placed between absorbent cloths and rolled with a steel rolling pin to remove excess water. The sheet is then dried between 50 mesh screens at C. and 50 lbs/sq. in. pressure for 10 minutes. The screens give a pattern to the resulting non-woven fabric similar to a woven fabric. The fabric is tested and found to have a tongue tear strength of 1.31 lbs./oZ./yd. and a drape stiffness of 0.81 inch.

Additional non-woven fabrics are similarly prepared using the same fibrids and the same self-elongatable fibers in differing proportions as set forth below. The following results are obtained:

All

Percent, Fibrids/ Tensile Tongue Drapa- Percent Fibers Strength Tear bility Comments Strength Fair Poor Good Strength too low. .ado Good l (lo Borderline. Excellent" Excellent. Excellent" Best combination. d0 Good Good Adequate.

Good Poor Poor Unsatisfactory.

From these results, it may be seen that when elastomer fibrids are used as the binder for the non-woven sheets of this invention, a minimum of 25% of such fibrids is needed, while anything over 50% fibrids gives less desirable sheets. Also, a minimum of 50% self-elongatable fibers is needed for soft, drapable fabrics. Using other elastomer fibrids, similar results are obtained.

EXAMPLE 2 A 46% solids dispersion of a polymeric acrylate ester elastorner containing 92% ethyl acrylate, 6% methyl 1 4 acrylate and 2% acrylic acir. fibrids as follows:

To a quantity of the dispersion sufiicient to contain 100 parts of elastorner is added parts of diepoxide resin, a monomeric bis-glycidyl ether of diphenylol propane having an epoxy equivalent of l752l0 (Epon 828, sold by Shell Chemical Corporation) and 5 parts of butylated melamine formaldehyde resin containing one part melamine to 45 parts formaldehyde (Uformite MM-46, sold by Rohm and Haas Company) and 5 parts of titanium dioxide pigment.

The compounded mixture is converted to fibrids by adding the resin blend to a Waring Blendor containing a 5% solution of sodium sulfate in hot water (75 C.) with 0.01% of an organic quaternary ammonium salt as wetting agent. The Blender is operated to full speed during the addition. The resulting fibrids are used in the form of the slurry thus prepared.

The staple fibers employed are similar to those of Example 1 with a spontaneous elongation of when immersed in boiling water for 5 minute A slurry of 3 parts of the above fibers with 2 parts of fibrids, in 10,000 parts of water, is prepared as in Example 3 and a we. erleaf is prepared in the manner of Example 3 also. The sheet is removed from the screen, placed between a cotton cloth sheet and a l2-mesh wire screen, and dried at 120 for 3 minutes. The dried sheet is then placed between 50-inesh screens and embossed and bonded by pressing at 205 C. for one minute at 200 p.s.i. The sheet is further cured by exposing to air at 165 C. for 5 minutes and then washed and tumble dried before testing. The fabric has a tensile strength of 5.9 lbs./in./oz./yd. a drape stiffness of 0.75 inch, and a wet tensile strength of 4.5 lbs./in./oz./yd. The fabric is found to have good strength retention when exposed to dry-cleaning solvents. The embossing treatment produces a fabric resembling Oxford cloth in appearance, with excellent whiteness, good retention of whiteness under laundering and pressing, medium porosity, and good handle.

During the process of curing and embossing, the sheet can be conformed, if desired, to a three-dimensional shape, of the flat sheet.

is converted to highly stable EXAMPLE 3 The compounded elastomeric mixture of Example 2 is used in this example without conversion into fibrids. The self-elongatable fibers are also the same.

The fibers are formed into a web by slurrying in water using a conventional fiber wetting agent and forming a waterleaf. The Waterleaf is air-dried on the screen, since it cannot be handled unsupported.

The elastorneric mixture of Example 2, diluted with an equal volume of 5% aqueous sodium sulfate solution, is used as a dip-bath. The waterleaf on the screen is immersed in the dispersion and excess bath is removed by blotting. The impregnated Waterleaf is placed in an oven at 160 C. with air circulation for 3 minutes, and the resin is coagulated by the action of the salt and the heat.

The waterleaf is removed and placed between SO-mesh screens and treated as in Example 5. The resulting sheet, which has the appearance of Oxford cloth, is composed of 66% fibers and 40% resin binder by weight. This sheet, while equivalent to the fibrid-bonded sheet in physical strength properties, is somewhat more porous and has a lower covering power.

In a similar manner, a solution of the compounded resin of Example 5 is prepared by adding acetone to make a 4.5% solids solution. The unbonded Waterleaf is immersed in this solution, the excess solution is drained off, and the impregnated waterleaf is placed in a pan of hot water (75 C.). This precipitates the resin and causes bonding. Then the sheet is dried on a sheet drier and is embossed and bonded and cured as in Example 2.

The resulting sheet is equivalent to the fibrid-bonded structure in all physical properties.

EXAMPLE 4:

A variety of synthetic elastomer resins are formed into fibrids by the procedure of Example 2. Table ll shows the results obtained by making non-woven fabrics employing 40% of these fibrids as binders, with 60% of the self-elongatable fibers of Example 1, using the procedure of Example 2.

E Ethyl acrylate-bascd copolymcr.

Outstanding physical propertiesgood dra-pability.

1 See Example 2.

EXAMPLE 5 A suspension of fibers is prepared by combining 10,000 parts of water with 3 parts of A1" long, 3 denier per filament self-elongatable polyester fibers of Example 1 (but having a spontaneous elongation of 10%) thoroughly wetted with a 5% solution of polyethylene oxide ether fatty alcohol surface active agent (Alkanol l-IC). To this suspension of fibers is added a sufficient portion of a slurry of 45/55 butadiene/styrene elastomer fibrids to provide 2 parts of fibrids in suspension form. These fibrids are prepared by combining a 45/55 butadiene/ styrene polymer in the form of a 56% solids dispersion in water with compounding agents as follows: 5 parts of finely divided pigment grade rutile titanium dioxide; 5 parts of zinc oxide; and 2 parts of Antioxidant 425, an antioxidant sold by American Cyanamid. This is dispersed with 12 parts of water to give a 50% solids dispersion. This is added to parts of the butadienestyrene polymer in a 56% solids dispersion in water. From this compounded resin dispersion fibrids are prepared by shear precipitation and coagulation. The coagulating system consists of a solution of 400 parts of water containing 0.31 part of aluminum sulfate 0.31 part of sulfuric acid and a small amount of organic surfactant (Triton X-100) wetting agent. A Waring Blendor is set to operate at low speed, and to the slowly stirred system is added a fine even stream of the compounded polymer dispersion described above. Suflicient quantity of the dispersion is added to be equivalent in volume terms to 2 /2 of the coagulation solution. After all the dispersion has been added, the system is allowed to stir for an additional two minutes to allow the binder particles to coagulate thoroughly to avoid agglomeration. The polymer from this reaction is obtained in the form of a fibrid slurry suitable directly for use in the preparation of a waterleaf.

This fiber-binder suspension is then poured into a headbox of a sheet mold, and a waterleaf is deposited onto an 8" x 8 IOU-mesh screen. Excess water is squeezed from the waterleaf by placing it while still on a IOU-mesh screen between absorbent cloths and rolling it with a steel rolling pin. The waterleaf is then removed from the screen and placed between SO-mesh screens, which in turn are placed between sheets of pulp board and dried in a press at C. and 95 lbs/sq. in. pressure for 10 minutes. Following this pressing treatment, the non- Woven sheet is obtained in the form of a fabric having a woven texture due to the imprint of the lOO-mesh screen and the SO-mesh screen which had been in contact with l3 it during pressing. The sheet is tested for physical properties and found to have a tensile strength of 3.12 lbs./ in./oz./sq. yd. and a tongue tear strength of 1.01 lbs./ oz./ sq yd. The drape stiffness in inches of the sheet 1% without printing, but dyed a red color with a dispersed dye.

A third fabric, weight 4.5 ozs./sq. yd, is prepared as above, except that 50-mesh screens are used instead of is 0.796. It is observed that Washing this sheet in a syn- 60-n1esh. This fabric is embossed in the same manner as thetic detergent followed by drying at 80 C. increases before and then dyed with a tan dispersed dye. This its strength as follows: tensile strength of 5.27 lbs./in./ material is used to make a wind breaker jacket and a pair oz./sq. yd; tongue tear strength of 1.16 lbs. /oz./sq. yd. of trousers. A separate portion of the same material is The drape stiffness is decreased slightly to 0.722 inch. screen printed with five colors, red, green, turquoise, gray,

EXAMPLE 6 and black, to give afloral design. L r

A number of fabrics are prepared in accordance with f??? piepaared, fahdricgeigltn 5.3 0.22] the procedures of Example 5 in different fabric weights L Fm a 2 W1 e d for evaluation as apparel fabrics. The first of these is Oosmg' Thfi pumgd fabric is then cut mic 9 an p p with a Wiqht of 2 5 OZ q y and is of a embossed between 24-mesh screens mounted on stainless v c 0 I Weight and handle ihdicating suitability for a shirting plfltes priss 3213 fabric. A sheet 5 feet long and 28 inches wide of the i i- Tie ii- 52 deposited waterleaf from a Fourdrinier machine is placed gnd gilg iidzc gteg a .10 rustle s ig L ,1, etween 60-mesh screen sheets which are in turn mounted l n n n 1 on stainless steel plates and placed between the platens th In -f j n fi gr a g fii a of a press and held there for 5 minutes at 140 C. and l e 0i l WeIgMLSi -f, i 135 lbs./ sq. in. pressure. The pressed piece obtained in igig l gg sg gg 3323 z gif g ig g g: as a sewn, and in every Way are equivalent to satisfactory i with a Weight of 3 5 07 q y is P1180 5 Woven fabrics, even though as already indicated they conc a prepared. This fabric is of a weight suitable for use as tam no Wovbn maienal' dress goods. As before, the fabric is embossed between EXAMPLES :2 60-: esh screens mounted on stainless steel plates. The white fabric, after pressing, is evaluated for sereen-pig- Table lll illustrates the advantages of the present inment printing. A pattern is applied with four diiferent vention and compares the fabrics produced with other colors: orange, yellow, black, and olive. The printed non-woven fabrics and also with conventional woven fabric is cured for 15 minutes at 350 F. The pattern is fabrics. A comparison of Examples 10 and 17 of Table sharp and the colors bright. Two dresses and two skirts III shows that, compared to the product of this invention, are prepared from the printed material, and in addition r self-elongation and development of crimp prior to web a skirt is prepared from a separate portion of the fabric 0 formation give a relatively inferior product.

TABLE III flomparison of Woven Fabrics With Non-Woven Fabrics of This invention Fabric Properties Ex. No. Fabric Type Composition Basis Thiclr- Tensile Drape Tensile/ Appearance Wt. ncss Density Strength Stiffness Drape (ca/yd?) (mils) (g./om. (lbs./in./ (inches) (lbs) 0Z./yd.

7 Cotton broad-cloth 100% woven cotton 3. 80 10.0 0.59 12. 5 0. 91 Typical woven fabric. 8 Cotton twilL.-- do 8. 5 21. 0 0.63 10. 0 0. 92 91 D0. 100% woven wool 8. 0 34. 0 0. 37 3. 5 0. 62 36 Do.

% 5.13. Fiber A; 3.5 14.0 0. 40 5.5 0.75 26 Very similar to woven 40% Fib id B, fabric; good covering power. 60% 5.13. Fiber A; 40% 5. 7 17.0 0.53 6.2 0.97 38 Like woven fabric.

Fibrid B. 60% SE. Fiber C; 3.5 13.0 0.42 4.2 0.75 20 Do.

40% Fibrid B. 8.13. Fiber A; 5% 3.5 19.0 0.28 3.4 0.07 12 Between woven fabrics Fibrid D. and felts. 14"," Non-woven resin bond- 60% SE. Fiber A; 40% 3. 6 14. 0 0.41 6.7 0.80 30 More porous than fibridd, Acrylate tcrpolymcr bomlcd fabric; good properties. 15 lo 60% 8.13. Fiber A; 40% 3. 6 14.0 0.41 5.7 0.80 26 Like woven fabric.

acrylatc terpolymcr 16 Commercial wool felt... wool fibers 5.5 39.0 0.18 7.5 1.28 32 Typipal felt; bulky and 1 17 Non-woven fibrid bond- 60% modified Fiber A; 3.3 11.0 0.47 4.1 1.14 12 Papery; too stiff.

ed. 40% Fibrid B. 18 do 00% Dacron staple; 3.5 9.5 0.58 5.1 1.56 11 Do.

40% Fibrid B. 19 do 60% crimpedDacron; 3. 3 10. 0 0.52 4. 4 1. 45 10 Do.

40% Fibrid B. 20 Commercialnon-woven. Pcllon020 (syntlictic) 2.6 26.0 0.16 3.4 1. 64 5 Very stiff and bulky. 21 do Clieopce Lustron 2.3 10.0 0.36 7.0 1.45 11 Still and papery.

rapery. 22 do Pcllon Polka-dot. t 2. 7 11. 0 0. 38 6.7 2. 65 7 Very stiff. 23 do Clgicfpec Mills Key- 2.6 12.0 0.34 3.3 above 3.0 3 Do.

SE. Fiber A-sclf-elongatable poly(cthylcno tcrephthalatc) fibers of Example 1. b Fibrid Bfibrids prepared from an clastomcric tcrpolyrncr based on ethyl acrylate as described in Example 5.

s S.E. Fiber C-selflelongatablc polyamidc fibers of Example 25. Fibrid D- fibrids of Example 24.

e Elastomer of Example 5 added as a dispersion in water (not as fibrid). f Elastomer added as a solution obtained by adding an equal volume of acetone to dispcrsion (5).

g Modified S.E. Fiber A obtained by elongating S.E. Fiber A in bulk form prior to use.

tancous elongation.

This gives a crimped staple fiber with no residual spon- EXAMIPLE 24 A copolyestsr consisting of 80% by weight of polyethylene terephthalate and by weight of polyethylene isoohthalate is dissolved in dimethylformamide to give a 26% solution. Forty parts by w c of this solution are added in an even stream to a mixture f 30 parts of water and 370 parts of dimethylformamide, chilled to below 5 C. in a Waring Blender operating at approximately 14,000 rpm. As the polymer solution is added to the cold precipitating solution, the polymer is caused to precipitate, and copolyester fibrids are formed. The fibrids are filtered and washed with water until free of organic liquids.

A non-woven fabric is prepared from a formulation comprising self-elongatable fibers of the type described in Example 1, together with fibrids as described in Example 24 using the procedure of Example 5. Because a highly efficient bonding is realized in this sheet, a low proportion of binder gives very satisfactory results. A sheet is prepared from 92.5% of the spontaneously elongatable fibers and 7.5% of the copolyester fibrids. After formation of the waterleaf, the fabric is dried at 130 C. between screens under a pressure of 50 p.s.i. and then fused between the same screens at 190 C. and 10 p.s.i. pressure. The sheet so prepared has a weight of 3.1 ozs./yd. a thickness of about 18 mils, a tensile strength of about 8.0 lbs./in./oz./yd. and a firm but flexible handle, rendering it suitable for use as a suiting interliner.

Other sheets are prepared, using the same fibrids and the same fibers, but in different proportions. It is found that when the amount of these hard (non-elastomeric) polyester fibrids is decreased to 2% or less, there is not sufficient binding action to provide a strong sheet. When the content of these fibrids is above about the sheets are very strong, but flexibility and drapability decrease. When as much as 50% of these polyester fibrids are used, the sh et becomes stiff and papery, even when optimum finishing treatment is employed. Similar fabrics can'be made on a continuous basis on a Fourdrinier machine.

EXAMPLE 25 t A polyarnide is prepared by melt polymerization from para-xylylene diamine and azelaie acid by conventional procedures. The polymer is then melt spun to give continuous polyamide filaments which are used to prepare spontaneously elongatable fibers. The spun filaments are drawn 3 at room temperature after being wetted with water and then relaxed in a 50 C. water bath to shrink them 45% of their drawn length.

The filaments are then cut into A staple lengths and are found to have a spontaneous elongation of 7% when immersed in 100 C. water for 5 minutes. A non-woven fabric is prepared using 60% of these staple fibers lengths) and 40% of fibrids of Example 1 according to the procedure of Example 2. The sheet is dried on a screen in an oven at 120 C. giving a soft, drapable fabric with good handle.

EXAMPLE 26 Sheets are prepared from poly(ethylene terephthalate) using the apparatus shown in FIGURE 5 of S.N. 859,614 of Kinney, filed December 15, 1959. Referring to that drawing, filaments 1 spun from spinneret 2 pass in the manner shown over the bar guides 3, 4, and 5, thence to aspirating jet 6 supplied with air under pressure through inlet 7. Aspirating jet 6 embodies extended filament passageway extension 8 fiared outwardly (6) at the terminus 9. The charged filaments 10, which separate on exiting the extension of jet 6, are collected on receiver 11, an aluminum plate. The various components downstream from spinneret 2 are grounded through leads 12. The pertinent distances along the filament line are as follows:

:13 inches e=ca. 4 inches [7:17 inches f=48 inches 0:20 inches g=7 /2 inches (1:23 inches [1:12 inches i6 The filaments are quenched with air, applied 6 inches below the spinneret face. The guide bars 3, 4, and 5 are 1" X 1" with rounded edges and are composed of chromic oxi'e. Guide bar 4, i.e., the functional surface thereof, is offset from the filament line by 2 /2 inches. The entire jet assembly is fabricated from brass.

In operation, poly(ethylene terephthalatc) (34 relative viscosit is spun through a 30-hole spinneret at a rat of 10 grams (total) polymer per minute. Each spinneret sole is 0.007 inch in diameter. The spinning temperature, measured at the spinneret, is 284 C. The following results are obtained:

TABLE 1V Filament Properties Air Pres- Run sure (P), 4

p.s.Lg. Tenacity, Elong, M1, g.p.d. Denier g.p.(l. percent f the runs reported in Table IV, process operability is good, as is sheet formation. The resulting sheets are substantially free from aggregated filaments, i.e., filament separation subsequent to charging is wholly satisfactory. Note that increasing air pressure results in a corresponding increase in the speed at which the filaments are delivered to the receiver; filament speeds increase from ca. 2000 yards per minute in run to 1 to ca. 3540 yards per minute in run 6.

ln each of the above runs, atmospheric steam at about 150 C. is applied to the separated filaments downstream from the aspirating jets, using a foraminous member disposed annularly with respect to the filaments, the filaments relax upwards to 20% or more with concomitant development of crimp. Upon later calendaring, the filaments in the sheet elongate spontaneously, thereby further contributing to the crimp level in the individual filaments and hence to the properties of the sheet.

When each of the above runs is repeated excepting that the filaments are collected on a moving belt partially submerged (over the area on which the filaments are collected) in 75 C. water, the filaments again relax, leading to the development of crimp up to levels of 50 or more crimps per inch (based on in situ examination). The filaments also spontaneously extend upon subsequent treatment at elevated temperatures.

The filaments also may be caused to relax by employing a heated gas in the aspirating jet. In one such run, air at 90 p.s.i.g. and C. was employed, leading to results similar to those described in the foregoing.

By repeating this example, excepting that 2 or 3 filaments by-pass the guide bars 3, 4, and 5 without contacting them, a sheet is collected which contains those less oriented filaments dispersed throughout as a binder fiber. Subsequent heating results in fusion of these filaments, leading to a more coherent sheet.

Continuous filament sheets of this type may be bonded with fibrids or with resin dispersion as shown in earlier examples. The sheets formed in all cases are equivalent to those obtained using self-elongat-able staple fibers and comparable bonding systems. Such sheet products are useful in all aspects of the present invention.

As is shown above, a number of highly desirable and useful non-woven fabrics can be prepared in accordance with the present invention. Such non-woven fabrics vary in fabric weight, fabric density, flexibility, strength, and handle. However, all 'of these materials have in common characteristics which suit them to meet the requirements and standards of woven fabrics, although they are, in fact, prepared without weaving operations.

EXAMPLE 27 Poly (ethylene terephthalate) continuous filaments were spun from a 34 hole spinneret to give a non-woven web of polyester fibers. The web consisted of individually dis posed randomly oriented filaments deposited through an air-jet which forwarded the filaments from the spinneret over a chromic oxide charging bar which caused the generation of a static electrical charge in the individual fibers, in accordance with the teaching of the previous example. The web contained oo-spun binder filaments of a copolymer of poly(ethylene isophthalate) and poly (ethylene tetrephrthalate) (20/ 80 composition) making up 10% of the total Weight of the web. The homopolymer polyQethylene terephtha'late) was spun under conditions to give filaments with controlled orientation to give from 25% to 55% shrinkage on treatment with 75 C. water for 1 minute.

Following web formation, the non-woven material was shrunk at controlled dimensions (on a tenter frame) to allow an area shrinkage of 50%, by treatment with 105 C. air with residence time of 1 minute. The filaments of the web were then found to be spontaneously elongatable, the average filament showing an elongation of 11% on treatment with boiling water for minutes.

The web, after shrinkage, was bonded and the filaments were simultaneously elongated by pressing the web between 40 mesh screens at 215 C. for 1 minute with a pressure of 200 p.s.i.

The resulting material was a soft, flexible non-woven fabric having a textile pattern imposed by the embossing function of the screens. The fabric bad a tensile strength of 7.0 lb./in./oz./yd. an elongation of 73%, a drape stiffness of 1.16 inches.

Similar reseults were obtained when the web was prepared without binder filaments, the binding action being provided by applictaion of an elastomeric dispersion of an acrylate terpolymer resin in water to give a binder content of 35% by weight based on the total fabric. The binder was applied to the web prior to shrinkage, and the final bonding action was completed by heating which simultaneously caused spontaneous elongation as before. This latter fabric had a tensile strength of 7.4 1b./in./ oz./yd. an elongation of 79%, and a drape stiffness of 0.95 inch.

We claim:

1. A c omformable, bulkable, non-woven web comprising at least 50% by weight of synthetic organic spontaneously elongated fibers, said fibers being capable of elongating spontaneously at least 3% upon heating at a temperature 30 C. above its second order transition temperature for five minutes, the web containing from about 3% to 50% by weight of a synthetic, organic polymer binder dispersed uniformly throughout the web, said binder having an initial tensile modulus of between 0.002 and 25 grams per denier.

2. The product of claim 1 wherein the spontaneously elongatable fibers are polyester fibers.

3. The product of claim 2 wherein the polyester is polyethylene terephthalate.

4. The product of claim 3 wherein the polyester fibers are staple fibers.

5. The product of claim 3 wherein the said polyester fibers are continuous filament fibers.

6. The product of claim 4 wherein the binder consists essentially of fibrids.

7. The product of claim 6 wherein the fibrids consist of an elastomeric acrylate copolymer.

8. The product of claim 5 wherein the binder consists of continuous filaments of a polyester having a melting temperature at least 20 C. below the melting temperature of said polyester fibers.

9. The product of claim 5 wherein the binder consists of fibrids of an elastomeric, synthetic polymer, which in fisher form has an initial tensile modulus of less than 0.9 g.p.d.

10. The product of claim 9 wherein the elastomeric polymer is a 'copolymer of an aliphatic ester of acrylic acid and up to 5% acrylic acid.

11. The product of claim 5 wherein the binder is in the form of fine particles.

12. The product of claim 11 wherein the binder is composed of an elastomeric synthetic organic polymer having an initial tensile modulus of less than 0.9 g.p.d.

13. The product of claim 11 wherein polymer is a copolymer of an aliphatic ester of acrylic acid and up to 5% acrylic acid.

14. The composition of claim 1 wherein the spontaneously elongatable fibers are polyarnide fibers.

15. The product of claim 14 wherein the polyamide consists essentially of a polymer of p-xylylene diamine and azelaic acid.

References (Iited in the file of this patent UNITED STATES PATENTS 895,480 Mathiesen Aug. 11, 1908 1,21 1,228 Price Jan. 2, 1917 1,712,002 Hea-ny May 7, 1929 1,834,364 Woodford Dec. 1, 1931 2,336,797 Maxwell Dec. 14, 1943 2,357,392 Francis Sept. 5, 1944 2,500,282 Francis Mar. 14, 1950 2,527,628 Francis Oct. 31, 1950 2,715,591 Graham et al v- Aug. 16, 1955 2,765,247 Graham Oct. 2, 1956 2,774,129 Secrist Dec. 18, 1956 2,808,349 Melamed Oct. 1, 1957 2,823,142 Sumner et a1 Feb. 11, 1958 2,930,106 Wrotnowski et a1. Mar. 29, 1960 2,931,749 Kine et a1 Apr. 5, 1960 2,988,782 Parrish et al. June 20, 1961 NITED STATES PAERFmE CERTIFICATE OF CORRECTION Patent No, 3,117,056 January 7, I964 Manfred Katz et a1" It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 53 after "has" insert not column 2, line 10, for "fabric" read fabrics column 5, line 50, for "poly(hexahydro-p-xylylene ter" read poly-N- methoxy hexamethylene column 7, line 36, after "such" insert as columns 13 and 14, TABLE III, third column, line 25 thereof, after "(synthetic)" strike out the subscript column 17, line 49, for "elongated" read elongatable Signed and sealed this 16th day of June 19640 (SEAL) Attest:

ERNEST W; SWIDER EDWARD J. BRENNER Altesting Officer Commissioner of Patents "UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,117,056 K January 7, 1964 Manfred Katz et a1,

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 53, after "has" insert not column 2, line 10, for "fabric" read fabrics column 5, line 50, for "p0ly(hexahydro-p-xylylene ter" read poly-N- methoxy hexamethylene column 7, line 36, after "such" insert as columns 13 and 14, TABLE III, third column, line 25 thereof, after "(synthetic)" strike out the subscript column 17, line 49, for "elongated" read elongatable Signed and sealed this 16th day of June 1964.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Auesting Officer Commissioner of Patents

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3259539 *Oct 28, 1963Jul 5, 1966Du PontPreparation of a conformable nonwoven web
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US3314122 *Jul 1, 1963Apr 18, 1967Du PontApparatus for forming non-woven web structures
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US3914497 *Sep 11, 1973Oct 21, 1975Kuraray CoNon-woven batts possessing excellent tensile strength, tear strength and initial modulus
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Classifications
U.S. Classification442/414, 8/130.1, 174/124.00R, 525/129, 525/110, 8/DIG.400
International ClassificationD04H3/16, D04H1/54
Cooperative ClassificationD04H3/16, D04H1/54, Y10S8/04
European ClassificationD04H1/54, D04H3/16