US2908064A - Non-woven filamentary products and process - Google Patents

Description

1959 H. ,G. LAUTERBACH EI'AL NON-WOVEN FILAMENTARY PRODUCTS AND PROCESS Filed Oct. 31, 1956 INVENTORS G. LAUTERBACH HERBERT -HARRY-M.

BY Q7 2'. (3M

NORTON ATTORNEY United States Patent O NON-WOVEN FILAlVIENTARY PRODUCTS AND PROCESS Herbert G. Lauterbach and Harry M. Norton, Wilmington, Del., assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Application October 31, 1956, Serial No. 619,469 18 Claims. or. 28-72) This invention relates to formation of continuous filamentary material into non-Woven coherent pliable feltlike articles. 7 p Felting of wooland fur represents the oldest method nized unsuitability of continuous filaments for similar processing, although relatively stiff and brittle articles can be formed from batts of continuous filaments by bonding of the filaments, as by fusion or use of an adhesive.

It is also know that'acrylonitrile polymer fibers do not felt well even in wool blends because of their stiffness. To prepare a good felt from acrylonitrile polymers or copolymers in blends with wool (50/ 50 or higher proportions of acrylonitrile polymer fiber) it is necessary to treat the blends with about aqueous sodium thiocyahate solution at about90" C. before felting.

Oneobject of this invention isto provide a non-woven Coherent pliable unbounded (i.e., unbounded and unadhered) felt-like article comprising predominantly syn- .thetic organic continuous filamentary material, said article being characterized by predominantly coplanar orientation of the filamentary components in superimposed layers with portions of some of the filamentary components from each layer oriented into at least one -adj-acent layer. 1 *Another' object of this invention is toprovide anonwoven coherent pliable felt-like article comprising retractable predominantly synthetic organic continuous filamentary material; also, the retracted article obtainable therefrom.

Another'object of this invention is to provide processes a for producing the above described articles. I Other objects of this invention, together with means "and methods for obtaining them, will be apparent from the following description and the accompanying diagrams. g

The felt-like articles of this invention resemble wool felts except for the different structure of the article and composition and character of the-filamentary material.

The structure may be distinguished' by the presence of superimposed layers of a preponderance of synthetic organic continuous filamentary material, portions of which are oriented into at least one adjacent layer of filamentary material, that is, portions of some of the filamentary material are oriented in the thickness direction of the felt-like article. The oriented filamentary material does not detractfrom the utility of the felt-like article but actuallylsubstantiafly reinforces the article and particularly-so because the filamentary material'is unfused'an'd unbonded and each filamentjs free tomotve over a'djacent filaments, thereby imparting great flexibility to'the 1 to this invention.

2,938,064 Patented Oct. 13, 1959 2 article. The felt-like articles of this inventionare easily distinguished from felted products containing thermo- .plastic fibers which have been bonded together by coating or impregnating with resins or heated until many of the filaments are fused together. In bonded articlesof this sort the adhered fibers are not free to move relative to one another, and these resin-treated or heat-bonded products are stiff and undesirable for many applications where the strong pliable long-wearing felts of this invention may be used to advantage.

Q The invention will be understood more readily by reference to the drawings. V Figure l is a schematic representation of apparatus useful in this invention.

" Figure 2 is a fragmentary perspective view showing filamentary material arrangement when first assembled into a loose batt.

' Figure 3 is a similar fragmentary perspective view showing the appearance of the batt of Figure 2 after portions of some of the filamentary material have been forcibly oriented by needle-punching. The upper and lower (horizontal) surface areas of the needled batt of Figure '3 are slightly less than that of the loose batt of Figure 2, but the thickness of the batt of Figure 3 is slightly greater than the thickness of the batt of Figure 2. "Forcibleorientation of portions of the filamentary mafterial results in contraction of the surface areas normal to the direction of needling of the batt and a slight increase in the thickness of the batt. I

Figure 4 shows the appearance of a batt comprising retractable predominantly synthetic organic continuous filamentary material after some of the filamentary material has been first forcibly oriented by needle-punching and then treated to retract the filamentary material. The batt is substantially more compact than an unretracted batt, andthe horizontal surface area of the needled, retracted batt is less than that of the batt prior to retraction. The thickness of the batt is usually slightly greater than the thickness of the unretracted batt.

Figure 5 shows a similar batt after forcible orientation I of portions of some of the filamentary material, retraction and pressing. Pressing does not change substantially either the horizontal surface area or the batt strength.

In the apparatus shown in Figure 1, movable belt 11 supports filamentary material being processed according Superimposed layers of filamentary material 12 are deposited on the belt by hand or mechanical means, as desired, for transport through needle loom 13 which reciprocates needles into and out of the looselayered batt of filamentary material, forcibly orienting portions of some of the filamentary components into at least one adjacent layer and preferably into a position substantially perpendicular to the faces of the batt. Needle-punching results in contraction of the surface areas of the batt normal to the direction of needling, and the needle-punched batt at 14 is shown to have smaller surface area than that of .the loose layered batt prior to needling. The needle-punched batt at 14 may be used without further treatment and is highly useful in a number of applications. A needle-punched batt of predominantly retractable filamentary material optionally may be passedthrough oven 15 to further compact the batt and increase its density by retracting the filamentary material. Retraction of ,the ,batt as by heating to, suit able temperature results in further reduction in the upper surface area of the batt, as shown at 16. Optionally, also ,a'retracted or unretracted needle-punched batt may be pressed by passing through rolls 17 which forwardthe batt to, a collection point. Roll pressurernay beadjusted to-compress the strip to, slightly reduced thi ckness, if desired. i

In generalgtli'e objects erthe'bi-"e'sm invention neat;

complished by forming a loose layered b'att of predorni inantly synthetic organic continuous filamentary material, the layered batt having substantially parallel top and bottom faces with predominant orientation of thecomponent 'filamentarymaterial parallel to thefaces of ;the batt, and forcibly orienting, portions of some off the filamentary jcornponents into at least one adjacent layer of filamentary material, preferably into a position substantially perpendicular to the faces of the batt, to produce a coherent non-woven felt-like article of unbonded filamentary materiaL HThe invention extends to exposure of such articles, 1n WhlCh at least part of the component filamentary material is characterized by a capacity for retracting (that l is, shortening, as by crimping or shrinking, upon being heated or otherwise suitably treated), to conditions effective to retract the retractable filamentary material, whereupon the batt becomes even more compact while remaining unbonded and felt-like; Thus, this invention contemplates as a; principal product a non-woven'coherent feltlike article of unbonded filamentary material'containing apreponderance of synthetic organic continuous filamentary material, in which portionsof some of the filamentary material are oriented in the thickness direction of the 'batt. The phrase ,predorninantly synthetic organic con- ,tinuous filamentary'material as used herein refers to filamentary material more than 50% of [which possesses gan'ic,'and continuous in character.

essentially three properties, namely, it is synthetic, or-

' Coherent non-Woven unbonded felt-like'articles may be prepared in accordancewith this invention using all unretractable filaments but in accordance with a preferred embodiment part of the; filamentary material used has the ability to retract when properly treated, as with'heat or a swelling agent. The retraction may result from a simple reduction in length (that is, shrinking) or from a distortion of the filament into an irregular shape asby crimping or curling or'both The retractability or degree of retraction refers to a free filament at the treating conditions and is expressed conveniently asthe percent decrease (based upon the original value) in shortest distance between-two points on'an individual filament; thus,

' when both shrinking and crimping occur, his a summation of the effect produced by diminution in length and assumption of a more irregular path between the points of measurement. In some instances, it is gdesirable to prepare articles in accordance with this invention composed entirely of retractable filaments. Materials not retractable under the conditions of treatment can be blended with retractable synthetic filamentary'mfaterial or layered with it in orderfto achieve-special effects,

Thus, glass filament which exhibits zero retractability and/or wool fibers which are essentially'not retractable may be blended with a'predominant proportion of synthetic organic continuous filaments. 7

All synthetic organic continuous filamentary material can be utilized in this invention and, where it is desired to produce a retracted product, practically all synthetic polymeric filament-forming compositions can be manufactured r so as to have the necessary retractability. In addition to those exemplified hereinafter, these polymers include polyamides (e.g., 'polyhexamethylene adipamide, polyhexazmethylene sebacamide, poly-epsilon-caproamide, and

copolymers of these or other polyamides),lpolyjesters (e.g., polyethylene terephthalate, polyethylene sebacate), polyesteramides, .polyureas, polyurethanes, acrylonitrile polymers (including copolymers of acrylonitrile, especially with other ethylenically unsaturated monomers, a,

such as vinyl chloride, vinyl acetate, methyl acrylate, and vinyl pyridine) vinylpolymers generally (e.'g., polyvinyl acetate, polyvinyl'chloride, and polystyrene), polymerized fluoroolefins (e.g., polytetrafiuoroethylene, 'polytrifluoro monochloi'oethylene, polyhexafluor'opropylene') polymer 'ja'cent layers.-

or mechanically by feeding them onto a collecting surface] where they accumulate in overlapping layers, the individual filamentary components in each layer being predominantly coplanar, lying parallel to the collecting surface and to the bottom and-top of the batt so formed.- Conveniently, the step of batt formation will be accomplished by mechanical means, such as forwarding jets, which may be operated to lay the filaments down at random or in some desiredpattern; The collecting surface -may be rotated-or; oscillated ,to promote even accumulation oflthe filamentsga moving belt used as the collecting surface also can convey the'formed loose layered batt tothelocation where portions of'some of the component filaments Will be oriented forcibly to a position substantially'pe'rpendicular to the faces of the batt. a i i Depositing filaments with fluid jets permits formation of batts by elimination of blending procedures, and-generally simplifies handling of starting materials. Italso facilitates the use of continuous monoor multifilaments,

' or continuous lengths of spun staple yarns in the preparation of the batt. V Heretofore, use of continuous filaments in felt structures hasbeen confined to woven backings or cores. Synthetic filaments are initially produced as continuous filaments, and use in this form simplifies the manufacturing operation. The use of continuous filamentsimparts added compactness and 'strengthtoi'the product, which may range from a soft pliable to'a hard Stlfi fClt. v y I l 1',

Regardless -of how the batt is formed, or the type of continuous filamentary materialused (e.g., bulked yarns, monofilament or multifilament 'yarns either twisted: or untwisted, rope, tow, thread, ribbon, spunstaple'yarns,

braid, etc.), the batt'will ordinarily havelbeenbuilt up a gradually by superposition of a number oflayers ofi-r'naterial. The resulting batt consists initially, of a loose,

fluffy mass in which filamentary components -rnay be oriented in layers usually in planes parallel to'thel belt or other surface on which the batt is formed; l f

'The linear azimuthal orientation of the layers 'of filaments in any loose batt may be random or may be. prey determined to any azimuthal angle. Preferably, the ,fila-I -mentary components of adjacent layers liejatanazi muthal angle of between about 45 and to onesana other and most preferably are oriented 90 from one an:

other. Desirably, adjacent layers of filamentary compoi nents will have an average difference in azimuthal linear orientation of at least 5.

For example, a batthaving random orientationwill have fan average difference of about 45? in azimuthal linear orientation between ade out! These filamentary components will remain oriente n layers moreor less parallel to the faces of the final prodnot unless some way is found to cause them tointerlock between, layers. A surprising feature of the presentwinvention is thejdiscovery that a coherent strong, pliable non-woven felt-like product having exceptional proper:

ties is obtained even when -relatively sm-allj numbers; of

thefilaments have been reoriented byneedle-punching so that portions of the filaments'are positione'dlin atileflst two layers offilaments. 1

V 'rhe preferred method of achievingthe required o r'ientas tion offilamen ts in the batt is needle-punching," which'gis convenientlyaccomplished in a conventional-needl loomt ized hydrocarbons (elg, polyethylene) and halogenated derivatives thereof, synthetic proteinaceous polymers, and t Such a loom has a large number of clbselyspaceda'ral rocatingneedles designed to tchr dra'g-"fila The filamentary mentary material as the needles move into the batt. Relative movement between the batt and the needling location may beeither intermittent (while the needles are drawn clear of the batt) or continuous. To maintain the dimensional stability of the batt during needle-punching, it isusually advisable to feed simultaneously to the needle loom a supporting layer, for example, a layer such as a cheesecloth, a film, or a warp of the. same fibers as in the batt. The supporting layer may be readily stripped after thepunchingoperation, or if of. the same fiber composition may'b e retained in the punched batt. This type of loom 'iswellknown for use in textile operations, so further description is unnecessary. {Of course, other suitablehmeansmay be. used for forcibly orienting filaments into-thedesired position; for example, the batt may be hand-punched with an instrument elfective to orient one or more filaments from the surface toward the interior oflthe' beitt, but such 'a procedure is quite tedious, of

course. t

. jProducts formed by needle-punching loose batts according to: this'invention have many of the desirable characteristics ofwool felts', despite structural dissimilarities observable upon close inspection. No difiiculty is encountered in're'aching and even exceeding in many cases customar'y' felt densities in these articles. They are readily distinguishable from non-wool felt-like products containing-thermoplastic filaments bonded by heat or adhesives toione-another' because of their superior pliability and higher. split strength compared with therelatively stifif -unyielding. character and low split strength of bonded structures. In tensile strength, the products of the present invention comparevery favorably with properties of conventional felts and felt-like products, including those made. from synthetic staple fibers.

-The. rather fuzzy surface of the product can be smoothed by pressing. A heated pressing surface may induce retraction of surface filaments, but the temperature should bemaintained below the softening temperature of-the. fiber to prevent fusion. This added compacting treatment" is not essential in the majority of uses, nor need the product be subjected to any equivalent of fullingL-z: The initial conditions of batt density and the intensity: of treatment can be chosen to produce practically any-desired density and .coherencein the product'without necessity for any rubbing pretreatment or fulling aftertreatment. 1; The. practice of this invention is exemplified below in some detailr. In all the examples, physical characteristics ofthe-articles mentioned were determined (unless otherwiseindicated) according to recognized felt testing methodsro'f the American Society for Testing Materials, specificallyiASTM-D-.-46153;

. W V EXAMPLE 11 ,Polye thylene terephthalate is melt-spun from flakes by theprocess described by Hebeler in Patent 2,604,689 into: continuous 'filaments of 3 denier each. A conventionaLtow-forwarding jet passes a bundle of filaments through an air diflfuser, which opens up the bundle, then ontoa cylindrical roll. The roll is rotated slowly and multifilament yarn is traversed back and forth the 'widthof the ,roll so that it winds in a helical configuration andthe filaments in adjacent layers cross at an angle of at least about 5-. After several minutes, the winding isdiscontinued ,andj the accumulation of yarn on the roll; is removed by cutting along the surface of the roll Pi? loosebatt of, filaments. Batt length is equivalent to the circumference of the roll and width is about the same as ;.,the; roll wi dtl 1 The. batt is passed through a needle loom :andjneedl'ed' alternately from the top and bottom forza-totalzofll6 times, (8 times per face of the batt). Each pass-through'the loom results'in. 120 needle penetrations'ipcr square inch ofbatt surface, a total of 1920 perietiations for the 16 passes. As a result of the neel. to;the roll axis. This forms a layered non-woven dling, the face of the batt contracts and the thickness increases. Density (areal) of the felt is 32 oz./ sq. yd. The product surfaces are quite smooth, showing only slight indentations produced by the needle-punching, and lack-; ing any visible recurrent pattern of orientation of the component filaments in azimuth. No needle-formed chan nels are apparent. The product has a high tensile strength but is pliable'enough to be bent easily by handabout a sharp corner without noticeable separation of filaments.-

EXAMPLE II Continuous multifilaments of crimpable polyethylene terephthalate retractable to the extent of at least about- 15% are produced by extrusion through a 34-hole spin neret and drawing by an air jet to approximately 3 denier per filament as disclosed by Hebeler in Patent 2,604,689. The filaments are blown apart by the jet and deposited unrelaxed in a perforated basket with the random assemblage accumulates to a depth of 1.5 inches. The specific gravity of the batt-like mass is about 0.01. Needle-punching the batt with a needle loom equipped with regular barbed needles (15 x 18 x 2-5 x 3 /2) results in 50 needle penetrations per squareinch of batt surface. After needle-punching once from the topvof the batt, it is turned over andrun through the needle loom again to punch it from the other side to give a specific gravity of about 0.11. The article so produced is a-co'} herent non-woven pliable felt-like product, suitable asa filter, of smaller face-surface area and slightly greater thickness than the batt prior to needling.

Immersion of the batt in boiling waterfor 2 minutes results in further retraction of the filaments and reduction of the area; of the batt by about 25%, producing an even more compact felt-like mass. Upon tensile testing (Instr on) of a 2-inch strip of the retracted product, a force of about 40 pounds is required to break it, corresponding to about 265 lbs/sq. in., at breaking elongation of slightly over l00%. The same force is necessary to break a similar strip. taken transversely to the one just tested. This article is particularly useful as a filter for liquids. f In the following examples the batts were" prepared from continuous multifilarnents collected onto a moving belt in overlapping layers in each of which the filaments were oriented; at ,45 9' to the direction of belt movement, being oriented at aright angle to one another in alteri-v nate' layers. This can be accomplished bymeans of de,-: liveryjets oscillating diagonally to the belt; however; the apparatus actually used comprised a rotating hollow shaft through which the yarn was passed and delivered onto two vertical screwsthat supported the yarn in an elongated oval and then dropped it on thebelt, being the apparatus shown in Figure 10 of 'a patent application filed by D. S. Adams and I. F. Bowling on September 10, 1954, as- Serial-No. 455,192, and described in their specification. Y A l EXAMPLE III 'Ar-batt 30 inches wide is constructed from 400 denier, 60. filament yarn composed of polytetrafluoroethylene on, a moving belt with-the filaments in alternate layers oriented at a linear azimuthal angle of about along diagonals of the belt as just described. The battiS, punched twice on 'a standard plateetype needle .loom (Hunter Machinerr Company) using regular 1 barbed needles (15 x 18 x 25 x 3 /2) so thatthe'batt receives 1 20 penetrations gper: square inch during each pass through the loom. The-batt is folded double and punched 5 additional times under the same conditions, alternately from. each side. .The batt then is doubled again. and punched .an additional 15 times, alternately from'; each side,:.withzthe same punching frequency as beforeuri'llhe batt,-contracted about 13% ,duringthe needling ancl was-converted to afelt-like product weighing 73. lbsAsq. yd which .isxusefuliasya filter for liquids,

during each pass. 7 ing the needling, resulting in a felt-like article Weighing especially corrosive fluids. to which ordinary filtercloths are not. resistant. j .1 ;.'.Duplication of the above procedure withhighly; drawn} (7 times) polytetrafluoroethylene filaments produces'a similar felt-like article that can be compacted further; by heating to a temperature of about 300C to -produce' a retracted but still unbonded pliable felt-like article. This product is particularly useful as a filter or as a. seal-' ing gasket.

EXAMPLE IV .A batt of continuous nylon (polyhexamethylene adipamide)v multifilament of 840 total denier'and 140 filaments with layer orientation as in Example III is punched 3 times from the same side to give a total nee dlingfrequency of 90 penetrations per square inch. Theneedled batt is. plied 3 times and punched once from eachside at a needling frequency of120 penetrations per square inch during each pass. The 3-ply Structure is then.

7 tripled again to a total thickness of 9 pliesand punched 10 additional times, alternately from each side at a needling frequency of 120 penetrations per square inch during each pass. A coherent felt-like article "useful as a polishing felt for glass results, having a density slightly in excess of the values for an SAE F-l wool. felt and a retracted needle-punched synthetic staple felt but with strength greatly superior to both, as indicated in the following table. The nylon felt is hard and relatively stiff.

Table I I Strength I a p .Weight Felt Density (lb./sq.. Tensile (rt/ c.) yd.) Split (lb./in.

. (lb./2 in. of width Width) per lb./ q Y Example IV .43 7.6 48' '190 Polyethylene terephthalate retraeted.. .37 6.4 45 99.3 SAE F-1 wool 34 7.6 83 31. 3

Tensile strength was measured according to A.S.T.M. procedures and the data adjusted to account for differences in density, etc., in order to proyide an accurate comparison between felts.

'- Table I shows that under comparable conditions articles produced from continuous filaments according-to the present invention have properties superior to wool felts or synthetic felt-like articles formed from needlepunched staple batts (even though retracted).

t EXAMPLE v Following the procedure of theabove two examples, a batt'with linear azimuthal orientation of the filaments abrasion ;resistance,as. by decreasing molecular-vorientav, tionof the filaments.'.,.: .1. L

Thecompactnessand strength oflthe-product o invention 'are not dependent upon ,interfiber ,adhesion'om softening and vpartial fusion; In fact, s'uchifufsionlisiuu-i;

by the subsequentfretraction by treatment with heatuoii" a swelling agent. The original: degreexofLmol'eculm'i orientation, usually largely the result. of..drawing,: may; be adjusted for a given use, With due regard to..the .d sired resulting fiber elongation and tenacity'andithetin-l fluencei of draw ratio upon'retractabilityofthepatticui lar synthetic filamentary materialused; .111;

Felt-like materials of substantially-any desired'cha'm acteristics may be formed according to this invention; Thus, rather than the type of product determining utility,

as so often happens, here the products-of theiinvention may be made so asto fill a wide variety. of uses fornon woven materials These felt-like materials may be. manufactured in suitable form for use as wet and dry felts; filter media, carpets and their underliner's, insulation;

sound absorbents, chemical-resistant work l'c'lotlies, and a many other industrial and apparel uses. The transverse and longitudinal properties may be made 'practically identical by blending or layering,or. wide differences be-i tween them may be secured by sufficient. orientation of the starting filaments orfibers. The shape ofthe:prod uct may be determined by placing the battagainst-or around a fixed form so that the batt assumesthei con figuration of the form during retraction, and-pressing may be used to improve shape correspondence in 'this process modification. i r

Any synthetic organic continuousIfilamentary ma; terial is suitable for use in the practice of inven tion By continuous, as used herein, .is meantJafiy length greater than about eight inches. Preferably,- con-. tinuous filaments having anaverage length greater than about eight inches are employed 'becausefneedling ofya loose batt of predominantly synthetic organic filamen'tary material having an average length of at'least about .eight inches results in contraction of the batt, thereby-' producing a strong coherent felt-like productwithout recourse to retracting the batt. Thus, merely needle-punching of about 90 diiferencebetween layers is constructed from high-tenacity rayon yarn (Super Cordura) hav-' ing a total denier of 1650, with 720 filamentswWith the needle loam and barbed needles of Example III this batt is punched three times from one side at a needling frequency of 30 penetrations per square inch during each pass. The batt is tripled by laying up three plies and punched for an additional 8 passes, alternately from each side, i'receiving' 120 penetrations 'per square inch The, batt contracted about 12% durinvention, and the retraction step: required {to render staple batts felt-like is renderedunnecessaryl The steps of crimping synthetic staple and carding synthetic stapleor wool" also are-obviated. Retraction is an optional final step in the practice of'the present invention; with some F materials *(eg; nylon) retraction tr'eatment":ad

vers'ely affects desirable characteristics of toughness and I tain, predominantly Icontinuous filament's, and theseafter" ncedlingr a loose batt of continuous, filamentary material ineaccoidance with this invention without'chemi ca l or heat treatment decreases the surface area of thebatt as con trasted with an increase in surface area when 'a 'loose' batt of conventional staple fibers is needle-punched ilf desired, blends with animal, vegetable, or mineral continuous filamentary material maybe employed although it is preferred to utilize synthe tic 'organic continuous filaments alone. Of'course, more thanonekind of fiila-l ment may be blended or layeredto'g'ether 'It'wi ll;'be'- appreciated that. needling ofia batt of continuous fila ments ,will result in breakingof some filamentsand that V the product produced may contain'a considerable num ber of broken filamentsdependiug upon the amount f needling. In all case's,';howe'ye'r, fthe product.wi lcon? ments will besynthetic' and organic in character. a I Most synthetic organic continuous filaments can be' produced retractable rem foru se according to a pro fen-ed embodiment; of invention in "which addition; al compactness isfindnc'ecl by retracti'ng 'the mama-fits I As suggested, thefretractionj' treatnient may consist of heatingbyvariousmean shy-applies: tion of Water,"oil,' steam," air orother fluid whicltl is relatively inert 'with respect to the particular filamutary'ma terial or it may involve exposure: of-"theLniaterial 102 a swelling agent in addition to'orlin place: ofothecheat treatmentI: A combination, of chemicaljandphysical;

For light-weight i mated treatments may be used, mild acid and alkali baths being examples of what often may be acceptable chemical treatments. Any method of shortening the end-to-end length of the filamentary material without too adversely affecting filament properties and fibrous structure is acceptable. If the filaments are to be retracted in a liquid bath, instead of by heating, a conveyor belt may be arranged to carry the batt through a tank where the filaments are submerged in or sprayed with the retraction-inducing liquid. This may be followed by suitable means for removing the liquid, such as wringer rolls and a drier, or by extraction, as will be understood in the art. The time of treatment may vary from a few seconds to hours, although for simplicity, times of the order of a minute or so are preferred. Either retracted or unretracted products of this invention can be pressed for smoothing of the surface or additional compaction of the filaments, if desired. Where a retracted batt is desired, it is preferred that the filamentary material utilized be retractable in length to the extent of at least about 15% in order to achieve substantial benefits from the retraction step.

In addition to the uses mentioned above for the products of this invention may be mentioned body armor and flak curtains, shaft packing, reinforced plastics, laminates, polishing felts, grease seals, wicking felts, mechanical felts, wet and dry papermakers felts, apparel felts, artificial leather, sanforizing blankets, tire cord fabrics, steaming pads, roll covers, and shock and vibration mountings. Many other suitable uses for these products will become apparent to anyone undertaking to practice the present invention.

In general, the continuous filament needled, unretracted felt-like articles of this invention possess superior abrasion resistance, chemical resistance, thermal stability, and tenacity to felt-like articles made from staple fibers.

This application is a continuation-in-part of application Serial Number 312,067, filed September 29, 1952, now abandoned, by Herbert G. Lauterbach and Harry M. Norton, and application Serial Number 436,014, filed June 11, 1954 by Herbert G. Lauterbach.

The claimed invention:

1. A non-woven coherent felt-like article comprising predominantly synthetic organic continuous filamentary material characterized by predominantly coplanar superimposed layers of the filamentary components, the filaments in each layer being oriented at an angle relative to adjacent filaments in adjacent layers, with portions of some of the filamentary components from each layer oriented into at least one adjacent layer.

2. The product of claim 1 in which the continuous filamentary components are at least partly retractable to diminished length.

3. The product of claim 1 in which the filamentary material is a polyamide.

4. The product of claim 1 in which the filamentary material is rayon.

5. The product of claim 1 in which the filamentary material is a polyester.

6. The product of claim 1 in which the filamentary material is polytetrafluoroethylene.

7. A non-woven retracted coherent felt-like article comprising predominantly synthetic organic continuous filamentary material characterized by predominantly coplanar superimposed layers of the filamentary components, the filaments in each layer being oriented at an angle relative to adjacent filaments in adjacent layers, with portions of some of the filamentary components from each layer oriented into at least one adjacent layer.

8. The product of claim 7 in which the filamentary material is polyethylene terephthalate.

9. The product of claim 7 in which the filamentary material is polytetrafluoroethylene.

10. The product of claim 7 in which the filament material is a polyamide.

11. A process for preparing a non-woven coherent felt-like article comprising forming a loose batt of predominantly synthetic organic continuous filamentary material as a plurality of superimposed substantially parallel layers, the filaments in each layer being oriented at an angle relative to adjacent filaments in adjacent layers, and forcibly orienting portions of some of the filamentary components into at least one adjacent layer.

12. The process of claim 11 in which substantially all of the continuous filamentary material is retractable.

13. The process of claim 12 in which the felt-like article produced is retracted.

14. The process of claim 12 in which the filamentary material is polyethylene terephthalate.

15. The process of claim 12 in which the filamentary material is polytetrafluoroethylene.

16. The process of claim 12 in which the filamentary material is polyhexamethylene adipamide.

17. The process for preparing a felt-like product which comprises forming a mass of heat retractable continuous synthetic filaments into a loose batt, said filaments being retractable by at least 15% in length when heated below the fusion temperature, punching portions of some of the filaments into the batt in a direction substantially perpendicular to the faces of the batt, and then without other treatment heating the filaments so that they retract at least 15% in length and remain free to move over each other though under frictional constraint from mutual contact until they retract sufiiciently to compact the batt to a felt-like product.

18. The process for preparing a felt-like product which comprises forming a mass of heat retractable substantially continuous polyethylene terephthalate filaments into a loose batt, said filaments being retractable by at least 15% in length when heated below the fusion temperature, punching some of the filaments for part of their length into the batt in a direction substantially perpendicular to the faces of the batt, and then without other treatment heating the filaments below the fusion temperature to cause them to retract at least 15 in length without adhering with resulting compaction of the batt to a felt-like product.

References Cited in the file of this patent UNITED STATES PATENTS Francis Mar. 16, 1948

Claims (1)

1. A NON-WOVEN COHERENT FELT-LIKE ARTICLE COMPRISING PREDOMINANTLY SYNTHETIC ORGANIC CONTINOUS FILAMETARY MATERIAL CHARACTERIZED BY PREDOMINANTLY COPLANAR SUPERIMPOSED LAYERS OF THE FILAMENTARY COMPONENTS, THE FILAMENTS IN EACH KAYER BEING ORIENTED AT AN ANGLE RELARIVE TO ADJACENT FILAMENTS IN ADJACENT LAYERS, WITH PORTIONS OF SOME OF THE FILAMENTARY COMPONENTS FROM EACH LAYER ORIENTED INTO AT LEAST ONE ADJACENT LAYER.

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