US 3565729 A
Description (OCR text may contain errors)
Feb. 23, 1971 L. HARTMANN NON-WOVEN FABRIC Filed 001;. Filed Jan. 29, 1964 5 Shgets-Sheet 1 o ooooo zlmgoo olooooooo' INV ENT OR LUDWG HART'MANN ATTORNEYS Feb.23, 1971 L.HARTMANN 3,565,729
NON-WOVEN FABRIC Filed Oct. Filed Jan. 29, 1964 5 Sheets-Sheet 2 mmihimiiaiidumb.
u 'INVENTOR JMlJiLUL v I wow/c HARTMANN "Ji -7 My ATTORNEYS Feb. 23, 1971 L. HARTMANN NON'WOVEN FABRIC 5 Sheets-Sheet 3 Filed Oct. Filed Jan. 29, 1964 FIBER. THICKNESS B/REFR/NGENCE 0F POLVAM/DE6 F/LAMENTS INVENTOR LUDW/G HARTMANN ATTORNEYS Feb. 23, 1971 HARTMANN 3,565,729
NON-WOVEN FABRIC Filed Oct. Filed Jan. 29. 1964 v 5 s t -she t INVENIOR wow/a HARTMANN ATTORNEYS Feb. 23, 1971 L. HARTMANN 3,565,729
NON-WOVEN FABRI C Filed Oct. Filed Jan. 29, 1964 5 sheets sheet 5 I N VENT( )R L UDW/G HA RTMANN 8%, 9.416 f lu ATTORNEYS United States Patent 3,565,729 NON-WOVEN FABRIC Ludwig Hartmann, Oberflockenbach, Germany, assignor to Carl Freudenberg, a corporation of Germany Division of application Ser. No. 341,489, Jan. 29, 1964. Continuation-impart of applications Ser. No. 254,601, Jan. 29, 1963; Ser. No. 302,370, Aug. 15, 1963; and Ser. No. 614,093, Feb. 6, 1967. This application May 29, 1969, Ser. No. 828,918 Claims priority, applicahgon (ziiermany, Feb. 3, 1962,
Int. Cl. B29f 3/01, 3/06; B29g 7/00 US. Cl. 156-441 7 Claims ABSTRACT OF THE DISCLOSURE Apparatus for producing non-woven fibrous fleeces. The apparatus includes at least one linearly aligned row of individual spinning orifices, each of which is adapted to have a synthetic fiber filament spun therefrom; means for impinging generally parallel air streams on both sides of the rank of filaments so spun; a multiplicity of channel means, each individually associated with a single filament, which filament passes through the channel and is drawn therein by the air stream; and fleece form means upon which the filaments are laid after they emerge from the Ehannels and upon which the filaments form a non-woven eece.
This application is a continuation-in-part of Ser. No. 254,601, filed Jan. 29, 1963, now abandoned; application Ser. No. 302,370, filed Aug. 15, 1963, now abandoned; and application Ser. N0. 614,093, filed Feb. 6, 1967; and is agiyision of application Ser. No. 341,489, filed Jan. 29,
The invention relates to the production of non-woven fabric articles from materials which can be provided in filament form, as by extrusion. The invention provides a new apparatus for production of filaments, and new non woven fabrics.
The starting material for the manufacture of non-woven fabrics is commonly staple fibers which are brought into a flat assemblage and fixed in place with the aid of bonding agents or by self-adhesion. In general, the high precision required in the manufacture of textile fibers as to uniformity of fiber thickness and length, is not as technically important in the case of non-woven fabrics. Consequently, attempts have been made to produce special fibers for non-woven fabrics, and furthermore, to simplify the processes of making fibers and non-woven fabrics by combining the two processes, i.e. production of fibers and production of fabric, into one operation. Thus, it has been proposed that solutions of high polymers be sprayed through round nozzles placed in a concentric air stream, whereupon fibrous mats are formed. These processes, based on a spray gun principle, have not achieved any great industrial importance because the fibers produce, and hence also the non-woven fabrics made, do not possess enough strength. This is probably due mainly to the poor molecular orientation of the chain molecules in the fibers thus manufactured, which evidently have been drawn very little or not at all. It has been proposed to use in place of the round nozzles, a fiat nozzle. The flat nozzle is formed of two wedges, into which longitudinal grooves have been cut, and the wedges are placed together so that juxtaposed holes are provided. The fused high polymer mass can be injected into two turbulent air currents and blown into fine fibers by means of the air currents. Since the wedges equipped with the longitudinal grooves have to be pressed tightly against one another, struts are required at certain intervals, and the struts hamper the uniform formation of fibers at regular intervals and, due to Patented Feb. 23, 1971 ice the turbulence which the struts create, they interfere with the formation of high-strength fibers and uniform fabrics of relatively great width.
The air streams which pick up the fibers become very turbulent after leaving the spinning nozzle, which interferes with well defined drawing conditions of the fibers themselves.
The above-mentioned disadvantages are overcome by the following invention, which makes it possible, by spinning fiberforming high polymers into directed gas currents of high velocity, to produce a uniform non-woven fabric of great strength. Furthermore, it has been found surprisingly that, by fusion spinning and drawing by means of directed gas currents, fibers of high molecular orientation can be produced. By directed gas currents according to the present invention, is meant those gas currents the various strata of which have the same direction of travel over a distance of at least 30 cm.
In the process of the invention, filament material is spun out in such manner that a plurality of continuous fila ments are formed simultaneously, said filaments lying rectilinearly alongside one another. This set of filaments is guided within air channels in such a manner that they do not contact one another. This is accomplished by means of currents which pick up the filaments as they leave the spinneret, draw them and solidify them and carry them in parallel paths within air channels away from the nozzle. This gas or vapor handling according to the invention results in a uniform formation of the groups of filaments coming from the spinnerets the entire group being carried away from the spinnerets within air channels in a parallel ribbon-wise arrangement, avoiding the combination of a plurality of filaments into a yarn or tow, and they are finally built up, by winding, collecting or criss-crossing,
' into a mat.
Thus, the invention provides a process for spinning of filaments which comprises issuing a fused polymer mass in the form of filaments from several linear rows of spinneret holes of a spinneret head, and directing gas streams into impinging and entraining relation with the issuing fused polymer filaments to draw them and orient polymer molecules in the direction of the filament axis. The mass is drawn to reduce the diameter from the diameter of the spinneret hole in the ratio of at least 30:1, and the filaments are cooled to a set condition wherein the molecular orientation is retained. The filaments are maintained in drawn condition during the cooling by gas streams directed against the filaments to urge them to the drawn condition. In practical application, a multitude of linear, parallel filament rows are simultaneously drawn while keeping them in parallel arrangements within the air channels, and the drawn and set filaments of the different rows are finally collected on a screen or perforated roll for the formation of a fleece or mat.
In this process a fiber-forming high polymer can be fed in fused form to a plurality of spinnerets, each of which consists of a linear row or line of more than, for example, holes, and an elongated gas discharge passageway can be provided on each side of the row or line of spinneret holes. The individual spinneret holes can have a diameter of 0.1-1.0 mm., preferably 0.2-0.5 mm. The length of the holes can be 3 to 6 times the diameter. The distance of the holes from one another can be 1 to 3 mm., and all of the holes in the same spinneret can be the same distance apart. The distance between the row of holes and the slit like opening for the discharge of gas is more than about 0.1 mm. and preferably is about 0.1 to 1 mm., desirably 0.2 mm. and preferably is about 0.1 to 1 mm., desirably 0.2 mm. Due to this close spacing, the gas stream does not have to be directed at any angle to the filaments, through an angle of a few degrees can be used.
The fused polymer is ejected from the spinneret holes in filament form. The filaments are immediately thereafter seized on both sides by heated gas currents discharged from two slit-like openings. The gas velocity is so adjusted that the filaments are carried away from the spinneret without breaking off, and so that the filament diameter decreases within a distance of mm. from the spinneret in a ratio of at least 30:1, but preferably higher. The gas currents producing the great cross-sectional reduction are guided in such a manner that, due to the smooth shape of the slits, turbulence at the outlets of the spinneret is suppressed and a substantially directed flow is obtained. At a distance of between 1 to 5 cm. away from the spinneret, the group of linearly aligned, parallel filaments from each individual spinneret, guided by the gas current surrounding it, is introduced into an air channel or guide passageway for the purpose of keeping the filaments, as well as the filament rows, in a parallel arrangement. This is important, not only for the formation of a uniform web but also for the undisturbed drawing and orienting of the filaments. After leaving the gas discharge passageways, the gas currents are no longer heated, but instead cooled off due to adiabatic expansion, in such manner that, at the distance of 5 cm. from the spinneret, the gas current can be chilled from, for example, 300 C. in the slit to 60l00 C. This cooling is of great importance to the filaments, inasmuch as the molecular orientation produced by the great cross-sectional reduction and by the stretching that takes place within a distance of 5 mm. from the spinneret, is more or less substantially frozen. The extent to which molecular orientation is achieved depends on the amount by which the filaments are stretched, which in turn can be controlled by the speed with which the polymers are ejected from the spinnerets and the speed and the degree of cooling down of the gas currents. The gas stream can cool by more than 100 C. in a distance of about 50 mm. to at least partially set the filaments. The guidance of the filament rows within the separate air channels is of great importance for the drawing and orienting process since it provides for turbulence-free conditions.
In one of the procedures of the invention, non-woven fabrics are manufactured by:
(a) extruding a material for formation of filaments, while in liquid state, through a plurality of juxtaposed openings to provide a plurality of spaced and parallel disposed non-solidified filaments of the material issuing from the openings;
(b) passing heated gas streams on both major sides of the group of parallel filaments to impinging and entraining relation with the filaments, the gas of the gas streams cooling down and converging with the path of the filaments and urging the filaments in the direction of the extrusion into the air channels while tending to maintain the filaments in said spaced parallel disposed relationship, the filaments at least partially solidifying during the impingement of the gas; and
(c) thereafter and while the filaments are in impinging relation with the gas and after leaving the guide passageways or air channels, collecting the at least partially solidified filaments together to provide a fabric form comprising the filaments. By this procedure, the material forming the filaments can be provided in the fabric form as monofilaments with statistically varying directions of the filaments, such as, for example, in a woven or knit pattern.
Gathering of the filaments together to form a fabric can be performed in various ways. A secondary gas stream can be passed into impinging relation With the filament forms along a path at an angle or perpendicular to the movement of the filament forms from the spinneret heat under the influence of the gas streams directed towards the filament forms from above and below the filament forms. The primary gas streams can, and preferably do, provide the filament forms in a plane. The secondary gas stream used to gather the filament forms together for the collection thereof into a fabric form, can then be a gas stream which passes through such plane and across the path of the monofilament forms, breaking up the plane of the filaments and causing the filaments to cross one another. The filaments can be gathered on a foraminous form which is moved a ross the path of the filaments. Desirably means are provided for oscillating the filaments relative to the form for providing an improved disposition of the fibers in the fabric. Following the gathering, the fabric form produced thereby can be calendered at, for example, room temperature or steamtreated to secure the filaments together. It can also be bonded with synthetic resins, especially if a soft hand is desired.
As well as providing a procedure for the production of non-woven fabrics, the invention provides a novel fabric structure characterized in that the fabric is constituted by monofilaments strands gathered together in a manner to provide a fabric thereof with statistically varying directions of filaments within the strands, and the filaments can be arrayed in a woven or knit-like pattern. Thus, the monofilament strands can be collectively arrayed in a fabric pattern, the course of the filaments varying in a statistically random manner. Further, the monofilament strands :can be gathered together on a form having the shape of a garment, so that a seamless garment can be formed of the non-woven filament fabric according to the invention. In the production of such garments the form for the garment can be wound with respect to the strands, so that the monofilament strands are gathered on the form in a manner to provide a nonwoven fabric therefrom. For the production of fabrics having a woven or knit-like pattern, the filaments can be collected on a screen having a woven, cloth-like pattern, by drawing gas or vapor through the holes of the screen. A preferred embodiment of the invention is the collection of filaments on a patterned foraminated form or screen, with means to increase the air speed towards the collection spots, as well as means to keep off the filaments from the undesired locations. Such means can be pyramidal studs or pins which are located on the collection form or screen wherever the holes or mesh of the woven or knit-like cloth should be. The pyramidal form of these pins or studs tends to guide the filaments into the right direction, as well as increases the air speed of the guiding air stream of the filaments towards the collecting spots. The filaments thereby settle in a pattern resembling cloth and can be bonded that way. They resemble cloth in appearance but are nonwoven and have statistically varying directions of the filaments.
A feature of the fabric of the invention is that the filaments have varying degrees of molecular orientation, due to variation in gas and polymer stream velocity over the slot width, and due to this, the fabrics have good strength and toughness since mechanical stress is absorbed by filaments having varying elongation characteristics. It is a further feature of the fabric and process of the invention that the degree of molecular orientation varies with the thickness of the filaments within the fabric, so that with decreasing thickness the orientation increases.
The invention is further described in reference to the accompanying drawings, wherein:
FIG. 1 is an end elevation view of a spinneret head according to the invention;
FIG. 2 is a side elevation view of the head shown in FIG. 1;
FIG. 3 is a schematic representation of apparatus according to the invention and using secondary air supply means;
FIG. 4 is an elevation view taken along line 4--4 in FIG. 3;
FIG. 5 is a dimetric view wherein production of a fleece-utilizing apparatus according to the invention is depicted;
FIG. 6, FIG. 7 and FIG. 8 are, respectively, side elevation, top plane, and dimetric views of another embodiment of the apparatus according to the invention, and indicating use of the apparatus for production of a fleece;
FIG. 9 is a graph showing birefringence in relation to fiber fineness;
FIG. 10 is dimetric view, partially in cross-section, showing apparatus according to the invention, wherein a plurality of the ranks of the filaments are simultaneously formed and are guided to a fleece form for collection as a fabric;
FIG. 11 is a diagrammatic representation of a fleece fabric according to the invention, having a woven-like pattern wherein the monofilaments are arrayed with statistically varying directions;
FIG. 12 is a showing corresponding to FIG. 11 and indicating a knit-like pattern; and
FIG. 13 is a showing of drum perforations and pyramidal studs for production of a knit-like pattern as is shown in FIG. 12;
FIG. 14 is a showing of collecting screen with pyramidal pins for the production of a woven-like pattern as is shown in FIG. 11;
FIG. 15 and FIG. 16 are cross-sectional views of fabric structures provided with an iron-on stiffener formed of monofilaments according to the invention.
The apparatus of the invention can include a spinneret outfitted with a spinneret head having a plurality of spinneret holes disposed in a line, desirably in a substantially straight line, for receiving molten filament forming material from the spinneret and issuing it in a plurality of molten parallel filament forms, and gas delivering means disposed adjacent the spinneret holes for directing the gas stream into the path of the molten filament-forming material as such material issues from the spinneret holes and for entraining the filament-forming material as continuous filaments extending from the spinneret holes and elongating the filaments and cooling them to set condition while introducing them to the air channels. The apparatus further includes a foraminous form disposed in the path of the filaments after they leave the air channel for receiving the elongated filaments and collecting them, with the monofilaments disposed in totally random (as in common felt), or random and pattern crossing relation to form a felted fleece, and means for moving the form relative to the elongated filaments to effect the collection of the filaments as an extended fleece.
As is shown in FIG. 1, a spinneret head 11 is provided with a multitude of aligned spinneret holes 12, and the head further includes gas discharge pasageways 13 which are in the form of elongated passageways having their outlet ends disposed substantially parallel to the spinneret holes 12.
As is indicated in FIG. 3, the spinneret head 11 may be mounted on a spinneret 12', with the spinneret holes 12, disposed for directing filaments toward the fleece form 14 which is rotated in the direction indicated by the arrow. Due to the action of gas streams discharging from the passageways 13, the issuing filaments are grasped by the gas streams as a plane of filaments extending substantially toward the fleece form 14. The filaments pass between the secondary gas supply conduits 15. Gas discharging from the secondary gas supply conduits 15 along with the filaments enters the guide passageway 39 and in cooperation with the guide passageway serves to maintain the filaments in a plane, accomplishes smooth drawing action and prevents entanglement thereof prior to the arrival of the filaments at the form 14. The fleece form 14 may be a perforated cylinder and suction may be applied to the inside of the cylinder via suction nozzle 38 so that the gas is drawn through the cylinder; the drawing of the gas through the cylinder will serve to break up the plane of the filaments and to cause the filaments to be arranged in a random and crossing relation on the form 14. Other means may be provided to break up the plane of filaments adjacent the fleece form 14, such as air supply means 38a and 3812 which will supply air streams cutting across the path of the filaments to disrupt the plane thereof. Further, the guide passageway or channel 39 may be rocked so that its discharge end pivots about its inlet end, whereby to facilitate the collection of the monofilaments into a fleece, and to facilitate crossing and mingling as well as accomplishing a pattern-like arrangement of the filaments. In the representation shown in FIG. 3, the spinneret 12, secondary supply conduits 15, and the air channel are mounted on a base 16 by brackets 18 and 19.
In the dimetric representation in FIG. 5, the filaments 21 are indicated as issuing from the spinneret hole 12 and are maintained in a plane by gas streams issuing from the gas discharge passageways 13. The filaments are maintained as a plane as they are moved by the gas stream within the guide passageway 39 to the fleece form 22, which, in this case is ellipsoidal in cross-section indicating that the fleece form may be of any desired configuration and thus may be of garment form.
As noted above, the spacing of the spinneret holes 12 form the gas discharge passageways 13 may be about 0.1-1 mm. This distance is indicated by the dimension S shown in FIG. 1.
In the apparatus shown in FIG. 6, FIG. 7 and FIG. 8, the device according to the invention includes a hopper 30 for the resin to be used to form the filaments, a conduit 31 leading from the hopper to the feed device 32 which is provided with a drive 33 for controlling the feed rate. From the feed device 32, the resin is passed to the manifold 34 where it is melted by application of heat from a heat supply source (not shown). Communicating with the manifold 34 are a plurality of spinnerets 35. Each of the spinnerets 35 is provided with a pump (not shown) driven by pump shaft 36, and is provided with a spinneret head as is shown in FIG. 1. Further, a gas supply line 37 com municates with each of the spinnerets to supply gas for the gas discharge passageways 13 (FIG. 1) of the spinneret heads. The gas passed through each of the lines 37 is heated by a heater (not shown). A rank 46 of filaments issues from each of the spinneret heads, and the spinnerets are disposed with the heads in parallel relation so that the ranks are in parallel planes. Spaced from each spinneret head in a position to receive the filaments issued thereby, is a guide passageway 39. The guide passageway or air channels 39 guide the filaments from the entrance end of the air channels to the exit end thereof which is disposed adjacent the fleece form 45, which in the illustrated embodiment is a screen. The guide passageways serve to prevent entanglement of filaments of one rank with filaments of another rnak, and further, serve to prevent entanglement of the various filaments of each rank, and keep them on parallel course. Also, the air channels serve to keep the air streams directed and to guide the gas streams along the lengths of the filaments so that the gas streams urge the filaments in the direction of travel thereof and tend to urge the filaments in the direction in which they have been drawn and suppress turbulence thereby allowing for smooth drawing action. In this way, the molecular orientation occasioned by the drawing is maintained during cooling of the filaments to the set condition, while the air stream has a great length of undisturbed filament for applying its frictional force thereto.
A screen is moved in the direction of the arrow across the path of the descending ranks of filaments 46 and collects the filaments as a fleece. To improve the distribution of the filaments as well as to improve their interfelting, the air channels 39 may be rocked as is indicated by the arrows 44. Thus, each air channel is mounted on a shaft 40 which extends in the direction of the transverse axis of the air channel and a pinion 42, is provided for the rocking action of the air channels.
To further facilitate the obtaining of a suitable distribution of filaments in the fleece, the ranks of fibers are disposed so that horizontal projection thereof in the direction 7 of movement of the screen 45, indicated by the arrow 50 causes such filaments to overlap each other. This can be best seen in FIG. 7.
In the embodiment shown in FIG. 10, the spinneret 12' is outfitted with a plurality of spinneret heads 11 each having a line of spinneret holes 12. An air passageway 13 is disposed adjacent each row of spinneret holes and on each side thereof. Resin is supplied by a conveyor 51 to a pump 52, which in turn moves the resin to the conduits system 61, whereby the resin is advanced to the spinneret holes 12. Primary air for assisting in the drawing of the monofilaments is introduced via conduits 56 and issues from the air discharge passageways 13.
The guide passageway interposed between the spinneret and the fleece form may be a square chamber with a centrally disposed opening for passage of the filaments extending therethrough, and with a plate disposed adjacent to the filament path through the chamber on each side of the filament path. Openings may be provided in the plates, the openings being formed to direct gas passed therethrough in the direction of and along the filament path.
In the embodiment of FIG. 10, a plurality of guide passageways, one for each row of spinneret holes, is provided in the housing 63. The housing 63 is constructed with openings 64 extending therethrough for passage through the housing of the filaments. Each of the openings 64 is bounded above and below by a plate 65, and the plates 65 are provided with openings 66. These openings are formed to direct air or other gas passed therethrough along the path of filament travel through the various passageways 64. Gas is introduced into the openings 66 in the housing 63 through inlet pipes 58. To provide suitable distribution of the gas, the divider plates 67 are provided. Filament ranks 46 issue from the spinneret holes 12 and pass through respective openings 64 in the housing 63, and on the fleece form 14. The fleece form is rotated in the direction indicated by the arrow thereon, and, the filaments from each rank are collected on the fleece form as a layer, providing a fabric of several layers.
A feature of the invention is that the filaments may be deposited on a fleece form to provide a fabric having a wovenor knit-like pattern. This may be effected by means of gas or steam currents utilized with an alteration of intensity corresponding to the pattern desired, and/or utilizing a selected pattern for the perforations of the fleece form on which the filaments are collected. This may best be accomplished by using a collecting screen or foraminous form, which in the places of mesh or holes of the woven or knit pattern have elongated guiding studs or pins. These studs or pins may be of pyramidal form and as close as possible leaving free and foraminous only the places where filaments would collect in order to have a wovenor knit-like mesh of strands. The pyramidal form provides narrowing air passages towards the collection screen, thereby increasing air speed towards the collecting points or lines of the filaments which helps very much in having good collecting performance. Whereas the fabrics so formed have a wovenor knit-like structure, they differ from the usual woven or knit goods in that the individual filaments or collections of filaments which form the Wovenor knit-like pattern change direction in a statistically random manner. This is indicated for a wovenlike pattern in FIG. 11, wherein the forms b indicate the overall pattern which, as will be observed, is that of woven goods. The direction of a mono-filament through the fabric is indicated by the dashed line a. The course of the filament is governed by the swinging action of the air channels, with lower swinging speed the course will be more curly, while with higher speeds there is a tendency to produce more nearly parallel filaments Within the strands. They also differ from regular Woven or knitted goods in that the strands which form the mesh are constructed of filaments with varying degrees of molecular orientation of chain molecules whereby the orientation increases with decreasing fiber thickness. Similarly, for knit-like fabrics, the overall pattern of the goods is as is shown in FIG. 12. The monofilaments are disposed to pro vide the fabric form b and the varying directions and paths of the monofilaments in the gOOds is indicated by the dashed line a for one of the filaments. A pattern for drum perforations and guiding studs corresponding to the knitlike pattern shown in FIG. 12, is shown in FIG. 13. The drum 70 is provided with perforations 71 and the projections 72 which have the form of a cone. For producing a woven-like pattern, as is shown in FIG. 11, the surface on which the filaments are collected may be formed of a screen having pyramid-like projections. Referring to FIG. 14, the screen 73 is provided with pyramid-like projections 74.
The use of guide passageways or air channels accord ing to the invention has been found to provide maximum uniformity of the fiber web over the entire width of the material and yet to prevent different drawing ratios of individual filaments. The swinging of the guide passageways provides a method of regulating the parallelism of filaments within given strands in woven or knit-like patterns. The higher the swinging speed, the more unidirectional is the lay of filaments within the strands while forming the mesh of woven or knit-like pattern. With low swinging speeds, a more curly pattern of filament deposition is obtained.
With the gas currents, according to the invention, filaments of 6 microns in diameter and less may be drawn directly from, say, 400 micron spinneret holes. Such a reduction in combination with rapid cooling results in high orientation of long chain molecules.
In the prior art spinning processes, such great stretching from the spinneret holes by mechanical devices results in the breaking of filaments. The present process is furthermore characterized by the fact that the gas currents which produce the drawing of the filaments out of the spinning holes and which provide the parallel guidance, should impinge upon the filaments for a distance of at least 300 mm. and preferably 600 mm. without the individual filaments being entangled with one another by turbulence. The use of air channels enables the realizing of such results.
The great cross-sectional reduction in the filament diameters orients the filament molecules, and the finer the filament is drawn, that is, the greater the ga pull, the greater the degree of orientation will be. As the fineness of the filament increases, the specific strength of the filament increases. The following tables list strengths of filaments which were spun from polycaprolactam according to Example 1, below.
Table 1 shows how the fiber thickness varies with the rate of flow of polymer per spinneret hole, provided the gas current flow remains constant:
1 Per spinneret hole in cc./minute.
Table 2 lists the strengths of such filaments in relation to thickness.
TABLE 2 Tensile strength Fineness in grams Fiber in deniers per denier 1 Thickness in microns.
The curve in FIG. 9 shows the birefringence of Polyamide-6 fibers in relation to fiber fineness. It is therefore apparent that, in the case of fine fibers, birefringence values are achieved which correspond to those of normally spun and mechanically drawn fibers in the cold state. If no special precautions are taken, the fiow of polymer as well as gas over the width of the long linear nozzle shows irregularities especially towards the ends of the slots. This results in having different air and polymer velocities. For instance in the middle of the slot the air velocity is lower as compared to the air velocity at the ends of the slot, a characteristic which becomes especially dominant in long slots. This results in the production of a spectrum of fiber thicknesses. It has been found that the birefringence of EXAMPLE 1 Granulated polyamide (polycaprolactam, melting temperature 210 C., relative viscosity 2.28) was melted in an extrusion worm press at temperatures increasing forwardly of 200, 220, 250 and 270 and fed to 4 spinning pumps. The spinning pumps pumped the materials to 4 spinnerets heated to 220 C., which each consisted of a row of 160 holes of a diameter of 0.3 mm. Each row of spinning holes had air slots of 0.2 mm. height at a distance of 0.4 mm. on both sides, along its entire length. The continuous filaments passing from the nozzles in the form of a broad, non-cohering parallel band'of a multiplicity of filaments were each seized on both opposite sides by air at a velocity of 200 m./
these different filaments increases with decreasing thickness, indicating increasing polymer molecule orientation. Whlch left slots heated to Production of a uniform non-woven fleece is possible by and Pulled forward thereby h filaments We re swinging the guide passageways so that a given line on the fi i acceleratfid from a veloclty of J collecting screen is served by several spinning holes. This the nozzle holes to about 1200 I wlfhm a difference in filament thickness may be avoided by having dlstance of 3 from the flozzle eXlt- At a dlstahce longer air slots than spinning rows in order to apply the of 30 from} nozzle exlt a row of filaments decrease in air speed to a place where no filaments are gether Wlth alt streams whlchby h h a formed and by having smaller spinning nozzles. However, Perature of was brought mto lts chahml, it has been found desirable to have filaments of different which air Channel consisted of boxhke ducts With the characteristics within one fabric. Filaments of different mensiorls of 35 Width 3 height and 58 length thicknesses give a better fabric surface. The thicker fibers and Whlch ducts were p on that end adjacent to th@ have higher residual elongations because of lower drawing 2 (entrance) n that end adjacent to the filament ratios and give the fabric a certain toughness, because celvlng Screen U- Each p g nOZZle had an h astressis li d h 11 1 channel associated therewith, which kept the filaments The felting of the individual filaments into anon-woven from each 1101116 separated from as Well as Parallel to f b i t k place on h b i of various i i 1 o each other. The air channels were rocked around an axis the one hand, the spinning speed is substantially higher which was at the entrance side, so that the exit side swung than the speed with which the fabric is taken out, the two back and forth 5 as indicated on G- 8. T i speeds being in a ratio of approximately 100:1. Thus, if Channels Were swung in parallel- The filaments were the web of filaments is blown onto a screen belt with a lowed to P through the atmosphere for 30 an after suction behind it, the filament can be laid on in loops of a leaving the air Channelsdiameter always greater than 1 mm., i.e. greater than the This passage was also in a swinging fashion caused by fi a ent Spacing, so that adjacent loops overlap. Another the swinging of the air channels which gave the filaments factor that contributes to the felting is the turbulence of heir direction of movement. The filaments were finally the gas current after it leaves the guiding channels and 40 collected on a moving screen which had a suction destrikes the screen belt. The turbulence of the gas also invice therebelow. The screen was moved forward at a vecreases as the deposit of fibers on the screen belt increases. locity of 10 m./min., while the rows of filaments coming The felting together of the ranks of filaments from differfrom the nozzles were interfelted into a cohering nonent spinnerets according to the invention is brought about woven fabric. The fabric was impregnated with a 30% by swinging the guiding channels or passageways. The -15 dispersion of polyacrylate resin (Butyl acrylate) and ranks of filaments follow the swinging movement without dried, giving a fabric containing a 30 g./sq. meter of intertwining inside of the channels. A frequency of as fiber and 10 g./sq. meter of bonding resin. many as to-and-fro movements per second is appropri- EXAMPLE 2 ate. In this manner, the po1nt of deposit of a particular filament can be displaced several times per second into the A gfannlate 0f Polycaprolactam Was meltarea of the adjacent spinneret and back, so thata satisfaced on a Worm gear P and fed t0 the pp toryinterfeltingis a hieved, ratus of this invention by means of spinning pumps, The bonding of the unwoven fabric thus produced can at a tempel'atum 0f The p g P p be brought about by various methods. The filaments can i at d th m l t four pinn rets heated to 230 be welded together by heat treatment or with the aid of C. Each of the spinnerets contained a rectilinear swelling substances. Secondary bonding agents in the line of spinning holes, 160 in number, each having a diform of dispersions or solutions can also be added. The ameter of 400 and each spaced from the next by 2 fabric can be needled. Particularly desirable effects can be mm. The row of holes was bounded on both sides, at 21 achieved by printing-on the bonding agents in certain patdistance of 0.4 mm., by air slots 330 mm. in length. In terns, because this especially preserves the inherent textileeach case, air currents heated to 230 C. were forced out like character of the goods. All fiber-forming polymers of the air slots at a velocity of 200 m./sec. The filaments that can be melted without decomposition can be used as issuing from the holes were seized by the bilateral air raw materials for the present process. currents and thrust forwardly, whereby, at a distance of The following table gives a perspective of a number of about 3 mm. from the spinneret they were accelerated fiber characteristics obtained with various raw materials: from a velocity of 1 rn./min. at the spinneret hole, to
TABLE 3 Rate Fiber of flow Velocity Spinstrength, through of gas Gas neret grams Fiber spinneret, in the temperatemporaper thickness Polymer ccJmin. slit m./sec. ture, C. ture, C. denier in microns Polycaprolactarn 0. 1 270 260 240 3. 2 ll. Polypropylene 0. 065 260 265 5. 0 8. 0 Polyethylene terephthalate... 0. 1 260 247 3. 5 13. 0 Polystyrene 0. 065 375 248 1. 5 13. 0
1000 m./min. At a distance of cm. from the spinneret the filament of each individual spinneret was introduced into a lengthwise air-duct in register with it, having inner dimensions of said duct being about 3 x 35 cm. and having a length of 58 cm. Until the filaments entered the air ducts, the air currents pertaining to each of the spinnerets had cooled down to 100 C. and maintained the filaments separated from each other. The air ducts assured that the individual filametns also remained separated from each other while proceeding downstream, while the set of filaments of each individual spinneret remained separate from the sets of filaments of the adjacent spinnerets. This made it possible to determine in advance the collection place of the filaments and particularly to facilitate patterned collection. The filaments issuing from four of the air ducts were collected on a screening drum, having holes (perforations) of about 2 mm. in diameter, arranged in a knit pattern. In checkerboard fashion the holes were surrounded by round pyramids of 2 mm. base diameter and 4 mm. height.
By blowing hot air currents through the filaments, both during and after collection, the filaments assumed an arrangement in accordance with the layout of the perforations on the collecting drum, and under the effect of the heat, the filaments became bonded together. In this manner, there was produced a type of textured (knit-like) fabric structure with statically varying directions of the endless filaments.
The unwoven fabric articles of the invention have a soft hand like woven or knit goods, and may therefore, be used wherever woven or knit goods or other such interlaced fabrics are used. The new process, however, substantially simplifies the manufacture of such textile products, since the fabric manufacturing process is coupled with the production of the fiber. In other words, it is not necessary for fibers to be made and then drawn and treated with spinning oil and sizing agents in a first series of procedures, and then to spin the fibers of filaments into yarns which then are used for the production of woven or knit goods.
The process of this invention also differs from the prior art production of unwoven fabrics wherein the starting material is staple fibers which are made into a fleece and cemented together with the aid of bonding agents. 'In processes of that kind, it is necessary to produce a relatively high number of bonds, in order to prevent individual fibers from working out of the fabric and fuzzing up the surface, a phenomenon which not only results in the destruction of the fabric, but also in a nuisance when the free fibers migrate, for example, to the outside of an outer wear fabric. Consequently, a relatively high proportion of binding agent is required to adequately fix the staple fibers. The result of this high proportion of bonding agent in many cases is a stiffening of the fabric or a loss of its soft feel.
In the process of the invention, these disadvantages are avoided and a simplified manufacture of unwoven fabric articles is achieved. The starting materials may be polymers such as polyamides, polyesters, polyolefins, polyvinyl acetate, polyvinyl chloride, polyvinyl alcohol, cellulose acetate or cellulose in dissolved form (viscose). These materials may be spun into continuous filaments by a melt or solution spinning process. In contrast to the prior art spinning methods, the process of the invention uses directed gas currents as the drawing medium while spinning from several linearly arranged rows of holes, whereby each row has two associated air slots, into an air channel. The air channels or guide passageways are spaced at a distance of between 1 to 5 cm. from the nozzle exit to allow for cooling of the gas currents. The air slots are parallel above and below each row of spinning holes. Preferably, spinnerets are used which have more than 100 holes per spinning nozzle. The spinning speed may be, for example, between 1,000 and 2,000 meters per minute, according to the thickness of the fibers.
The band of filaments of each individual row of spinning holes, upon leaving the spinneret, is seized from above and below by a primary current of gas and accelerated, resulting in a reduction of the filament cross-section from, for example from 300 microns to 15 microns. The purpose of the primary gas or vapor current is to perform this drawing action and keep the filaments separate from one another. Furthermore, the primary gas or vapor current in many cases causes a stiffening or solidification of the filaments, at least on the surface. Then the bands of filaments are introduced into the air channels and seized by secondary gas or vapor currents which may produce a final solidification and guide the filaments on their parallel course and prevent them from combining and entangling. The gas or vapor currents have a velocity greater than the spinning speed, so that they not only stretch the plastic substance as it comes from the spinneret, but also solidify and draw the filaments. In the case of thermoplastics, the filaments are solidified by cooling from the molten state. The filaments, however, may also be solidified by precipitation by using, for the acceleration and guidance of the band of filaments, vapors which pre cipitate solutions of high polymers in filamentary form. The solidification of the filaments coming from the spinneret may also be accomplished by chemical action, by using acid vapors, for example, of xanthogenate solutions.
When the bands of filaments are collected, for example, on a screen with vacuum apparatus behind it, the individual filaments are superposed by criss-crossing or winding entanglement, and are stripped off in the form of a jumbled structure. The stripping speed is always lower than the spinning speed. To increase its strength, the fleece that has been formed from continuous filaments may be needled, by means, for example, of the needle punching apparatus described in Textile Industries, September 1958, page 117, wherein needles equipped with barbs are used, which catch certain filaments and push them through the fleece, whereby a loop of continuous filaments is formed. If the material has been appropriately compressed, a drawing of the filaments takes place which is particularly effective if the needling process is repeated several times. This process results in a considerable further strengthening of the fabric. The materials thus manufactured distinguish themselves by a combination of high strength with a soft, pleasant cloth-like hand. Nevertheless, they may be further treated to achieve special properties. For example, it is possible to achieve woven fabric-like materials by calendaring the non-woven fabric of this invention with embossed rollers; this gives the material a better hand and it may be sewed rapidly and securely. It has furthermore been found that the filaments in the materials of the invention are welded to one another by calendering at room temperature in such a manner that a firm bond results. It is possible in this manner to produce paper-like materials.
Binding agents as are appropriate can be used to effect such bonding as is desired, though as is noted above, substantially less bonding agent is required than in the case of felts formed of staple fibers. Heat treatment may be used, and it has been found desirable to employ superheated steam since this assures satisfactory heat transfer through a substantial thickness of fleece.
By subsequent impregnation with synthetic resins or sizes, the properties of the products of the invention may be improved. For example, impregnation with silicone resins has resulted in an improvement in ironability. Thermal post treatment is often desirable. If, for example, the product is made by the spinning of polyvinyl alcohol, the finished product may be made more ironable by tempering at elevated temperatures. A substantial improvement in launderability has been achieved by treatment of the fabric with cross-linking resins, such as those containing free methylol groups.
After appropriate pore filling and compression, the materials can be surface coated to produce leather-like materials. The advantage of the fibrous materials of the invention in this case is also and especially the fact that the continuous filaments do not contain any sizing agents and thus have an outstanding ability to adhere to the bonding agents used in the manufacture of artificial leather. This adhesion can be still further improved by performing the spinning process with a slight oxidation of the fiber surface as for instance that which occurs by spinning under an oxygen atmosphere. It has proven surprising that, when the fibrous materials of the invention are used, for example for the improvement manufacture of artificial leather materials, especially smooth, uniform products are obtained.
Further, paper-like products may be produced from fleeces according to the invention. Suitable materials may be used as fillers to fill the pores for appropriate consolidation, and by such procedure, it is feasible to produce fully synthetic, paper-like materials with a high degree of strength.
The invention has special application to the production of iron-on stiffeners, or to joining webs.
Recently resort has been had in the processing of textiles to stiffeners (linings, interlinings) which are not sewed on but rather are secured to the base cloth by an ironing process. Generally speaking these stiffeners consist of fabrics or webs which are coated with a thermoplastic adhesive mass. The adhesive mass must be deposited, preferably not in the form of a sheet, but, for example in a dotwise coating, in order to obtain porosity in the finished product, for example articles of clothing. The web or the fabric serves in many instances only as a supporting material for the adhesive masses. As an appreciable simplification it has been proposed to dispense with the supporting material. This could be accomplished, for example, by producing the iron-on textures or webs from thermoplastic fibers, which may be ironed on by applying an appropriate heat on the base cloth, which is to be stiffened. This simplification has not been successful inasmuch as the thermoplastic fibers produced heretofore could not be ironed on at sufiiciently low temperatures to the base cloth with a sufiicient degree of adhesiveness, or because the adhering surface was not resistant to cleaning or washing.
On the other hand, polymers or polymer mixtures which may be ironed on, even at lower temperatures, and which are at the same time also resistant to washing or cleaning, are known. However, these substances cannot be processed by the conventional spinning methods to yield fine fibers of suflicient strength to produce textile webs.
These drawbacks have been obviated by the present invention. Pursuant to it, a fibrous web is produced directly by spinning of such chemical substances as may be ironed on at temperatures ranging from 110-180 C. and which is resistant to washing and cleaning.
The advantages of such a material, as against materials known hitherto, also resides in the fact that it is adhesive on both sides, and that owing to the absence of a carrier or supporting fabric, it does not make the end product too stiff or bulky. The spinning process is conducted in the manner described above wherein the filaments are spun out of special spinnerets with the aid of directed air currents. The oriented air currents serve in this connection as drawing and stripping devices. The advantage of spinning with oriented air currents resides in the fact that the ironon substances, may be spun out without breaking. Such air currents are in contrast to strongly eddying air currents which would snap off the spinning mass upon such issuing from the spinning holes. Thus, it becomes feasible to spin, into textile webs built up of yarns, even such substances or mixtures of substances which have but a slight tendency to the formation of fibers.
In this connection, the process is conducted in such a manner that melts or solutions, or mixtures containing softening agents or softeners, and consisting of adhesive high polymers, are spun with the aid of spinnerets into lengthwise chambers, as are described hereinbefore and as are disclosed in application Ser. No. 302,370 filed Aug. 15, 1963. In the chambers or guide passageways the filaments are maintained mutually separated and are drawn and solidified with the aid of the oriented air currents. In this connection, the velocity of the air may be fixedvin such a manner that the layer of air closest to the filaments at the outlet of the spinneret (i.e. the initial velocity of the air), has more than times the velocity of the filament, preferably sufficient so that the velocity of the filament commencing with the spinneret increases SOD-fold within a distance of 5 cm. owing to the lag caused by the frictional forces of the air currents. The expression oriented air current is intended to have reference to air currents which exhibit markedly identical directions of flow at different layer levels. The oriented air currents render it possible to obtain a great elongation in the spinning and drawing of complex mixtures, and also permit collection as webs of desired form. This is also true in the case of such fibers which will not withstand a normal carding process.
Apparatus as is described hereinbefore may be utilized for production of the iron-0n stitfeners. Desirably the air jet above and the air jet below the filaments are oriented air currents, and the velocity in each may be such that the velocity in the stratum adjacent the filaments is highest, and the velocity decreases from stratum t0 stratum in the direction away from the filaments. Multiple slots or nozzles may be used to produce each air stream to facilitate obtaining the desired gradient in velocity. Upon issuing from the guide passageways, the filaments may be picked up with the aid of a suction device as is shown in FIG. 3 and may then be consolidated to a continuous web. The consolidation takes place, for example, with the aid of heated rollers, whereby the yarns are made to adhere to each other by virtue of their natural adhesiveness. However, any other consolidating method may be resorted to. Generally such methods are preferred as do not require any additional binding agents, except where special effects are sought which are brought about by means of a binding or finishing means.
The iron-on fabrics of the invention may be utilized entirely as a binder, since no backing or support is required, or, alternatively, as binder and stiffener. In FIG. 15, a base fabric 78 of polycaprolactam, is stiffened by a fleece 79 made, for example, according to Example 2 hereof, and ironed on by application of a heating instrument to the surface of the fabric 78 opposite the fleece 79. A sandwich structure, as is shown in FIG. 16 may also be made. The outer and inner fabrics 78 and 80 are bonded by the fleece 79. Fabric structures, such as those shown in FIGS. 15 and 16, may be porous since the fleece may be applied so that an impermeable film-like layer is not formed from the fleece. The bonding by the monofilament fleece of the invention is a direct bonding of the fleece to the contiguous material. The ironing-onmay be by any suitable means for softening the fleece to permit adhesion thereof to the adjacent material.
EXAMPLE 3 A granulate of high-pressure polyethylene (melting index 72), was melted at a temperature of C. and fed to a spinneret of 260 C. The spinneret consisted of a row of 20 holes with a diameter of 0.4 mm. and a spacing between the holes of 3 mm. The row of holes was bounded above and below at a distance of 0.2 mm. by an air slot which was 0.3 mm. in height and 68 mm. in length. Two air jets, each one of them at 260 C., were forced through the two air slots. These air jets seized the melts issuing from the spinning holes and drew them in the forward direction to form filaments. At a distance of 3 cm. from the spinneret head, the filaments entered a guide passageway with a plate spacing of 30 mm. The
15 air jets were developed by a pressure of 1 atm. and caused an acceleration of the filaments from 1 m./min. in the spinneret bore to 500/m. per min. at a distance of 60 cm. from the spinneret. The filaments were captured by means of a wire screen in the form of a fibrous web, and consolidated by means of steam treatment wherein steam was passed through the web to effect a suitable bonding.
EXAMPLE 4 A mixture of 1 part of a polyamide mixture of caprolactam and adipinous hexamethylene diamine and 1 part of 2-ethyl-hexanolpara-oxybenzoic acid ester was melted in a worm gear press at a temperature of 130 C. The melt was supplied to a spinneret heated to 160 C. The spinneret was mounted, as indicated in Example 3. The air jets on leaving the slot, exhibited a temperature of 160 C. The air jets were produced under a pressure of 1.2 atm. at the slots. The fleece, produced in accordance with Example 3, exhibited an adequate initial adhesiveness on reaching the screening drum to assure mutual consolidation of the fibers.
EXAMPLE 5 A mixture of 1 part of cellulose acetate (39% acetyl) and 1 part of diethylphthalate was melted in a Worm gear press at a temperature of 170 C. The melt was supplied to a spinneret which had been heated to 190 C. The spinneret was mounted as indicated under Example 3, and the air jet, on leaving the slots, exhibited a temperature of 190 C. The air jets were produced at a pressure at the slot of 1 atm. The fleece produced on the screening drum by suction was consolidated by passing such through rollers heated to 150 C.
The iron-on fleece may be of any suitable weight for the task to be performed. Thus the weight may be such as to provide a desired stiffening effect. Where the fleece is to serve merely the function of joining two webs to form a sandwich, the fleece may appropriately be light. The fleeces may, for example, weigh 5-50 grams per square yard, and will commonly preferably weigh 5-25 grams per square yard. The fineness in denier may be in the order of tenths and above, for example 0.3 and above. As a range the denier may be about 0.35, preferably 0.5-3.
As to the composition of the monofilaments, this may be any one of a wide range of materials and mixtures. Thecomposition should soften in the range of 110180 C. and should be formable into monofilaments by the process of the invention to provide monofilaments of great length, i.e. it should be possible to continuously spin the composition by the process of the invention utilizing oriented air jets, without substantial breakage of the monofilaments. Examples of suitable compositions are polymers and polymer softener mixtures, such as branched polyethylene preferably having a melt index in excess of 70, polyamides and softeners preferably mixed polyamides and ester softeners, and mixtures of cellulose acetate with softeners.
While the invention has been described with respect to particular embodiments thereof, these various embodi ments are merely representative of the invention and do not serve to set forth the limits thereof.
What is claimed is:
1. Apparatus for the continuous production of non- Woven fabrics which comprises spinneret means having at least one substantially linearly aligned row of spinning nozzles, means adjacent said spinning nozzles for impinging a gas stream onto two opposite sides of the rank of filaments spun from said row of nozzles; channel means proximate to and spaced longitudinally from said spinneret adapted to be associated with a single row of filaments and adapted to receive said filaments and at least a portion of said gas stream therein and to receive such filaments in a tacky state and pass such therethrough spaced from the walls thereof, said channel means having an inlet operating in substantial alignment with and spaced from said spinneret and from said gas means; and continuously moving fleece-forming means including a fleece form spaced from the end of said channel means opposite to the end thereof adjacent to said spinneret and disposed at an angle to said filaments adapted to receive said filaments upon emergence thereof from said channels.
2. Apparatus as claimed in claim 1, wherein said fleece form contains perforations therein, which perforations are in a mesh pattern.
3. Apparatus as claimed in claim 1 wherein said gas delivery means comprises means providing an elongated opening on each side of and adjacent to said row of spinning nozzles.
4. Apparatus as claimed in claim 1 including a second gas delivery means disposed intermediate the ends of said channel means which is adapted to impinge a second gas stream upon said filaments within said channel means.
5. Apparatus as claimed in claim 1, including a multiplicity of substantially parallel rows of spinning nozzles.
6. Apparatus as claimed in claim 1, including means for heating said gas before impingement thereof upon said filaments.
7. Apparatus as claimed in claim 1 wherein said fleece form comprises a formaminous rotatable hollow drum and including suction means operatively associated with said drum adapted to provide a pressure decrease from the outside to the inside of said drum.
References Cited UNITED STATES PATENTS 2,577,205 12/1951 Meyer et al 156-497UX 2,689,801 9/1954 DAlelio 156497UX 3,314,840 4/1967 Lloyd et al. 156-441 BENJAMIN A. BORCHELT, Primary Examiner T. H. WEBB, Assistant Examiner US. Cl. X.R. 156-167