US 3502763 A
Descripción (El texto procesado por OCR puede contener errores)
March 24, 1970 1.. HARTMANN 3,502,763
PROCESS OF PRODUCING NON-WOVEN FABRIC FLEECE Filed Jan. 27, 1964 5 Sheets-Sheet 1 I NVENTOR LUDW/G HART/MANN ATTORN S March 24, 1970 L. HARTMANN 3,50
PROCESS OF PRODUCING NON-WOVEN FABRIC FLEECE I Filed Jan. 27, 1964 5 Sheets-Sheet 2 INVENTOR LUDW/G HARWANN March 24, 1970 HARTMANN 3,502,763
PROCESS OF PRODUCING NON-WOVEN FABRIC FLEECE 5 Sheets-Sheet 5 Filed Ja n. 2'7, 1964 vU-n" v DERNIER.
FIBER THICKNESS B/REFR/NGENCE OF POLVAM/DE-fi F/LAMENTS IN V EN TOR LUDW/G HART/MANN PROCESS OF PRODUCING NON-WOVEN FABRIC FLEECE Filed Jan. 27, 1964 L. HARTMANN March 24, 1970 5 Sheets-Sheet 4 I NVENTOR LUDW/G HARTMANN B K 504 Q March 24, 1970 1.. HARTMANN 3,
PROCESS OF PRODUCING NON-WOVEN FABRIC FLEECE I 5 Sheets-Sheet 5 Filed Jan. 27, 1964 ZNVENT OR wow/a HA RTMANN aiws United States Patent Int. Cl. D04h 1/72 US. Cl. 264210 8 Claims ABSTRACT OF THE DISCLOSURE Process and apparatus for producing non-woven fibrous fleeces as well as the fleeces so produced. 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 channels and upon which the filaments form a non-woven fleece.
This application is a continuation-in-part of application Ser. No. 254,601, filed Jan. 29, 1963, and of application Ser. No. 302,370, filed Aug. 15, 1963, both now abandoned.
This invention relates to the production of non-woven fabric articles from material which can be provided in filament form, as by extrusion. The invention provides a new method for production of filaments, new non-woven fabrics, and new devices for production of such materials.
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 produced, 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 flat 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 the turbulence which 3,502,763 Patented Mar. 24, 1970 the struts create, they interfere with the formation of highstrength 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 covercome by the following invention, which makes it possible, by spinning fiber-forming 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, we mean those gas currents whose various strata 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 filaments is 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 separate 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.l1.0 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 split-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. Due to this close spacing, the gas stream does not have to be directed at any angle to the filaments, though 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 5 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 ribbon of parallel filaments from each individual spinneret, guided by the gas current surrounding it, is introduced into a separate 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 action 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 60-100 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 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) Extrudin g 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 from above and below the parallel disposed 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 and entrainment with 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 monofil-aments 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 head under the influence of the gas streams directed towards the filament forms from above and below the filament forms. The primary gas streams from above and below the fil ment forms can, a d preferab y o, p ovid 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 monofilament forms, breaking up the plane of the filaments and causing them to cross one another. The filaments can be gathered on a foraminous form which is moved across the path of the filaments and 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 provided thereby can be calendered at, for example, room temperature or steam-treated to secure the filaments together. It can also be bonded with synthetic resins, especially if a soft feel 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 monofilament strands gathered together in a manner to provide a fabric thereof with staistically 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 staistically 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 knitlike 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 non-woven and have statistically varying directions of the filaments.
A feature of the fabric of the invention is that the filaments have varying degrees or 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 orientiation 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 the line 44 in FIG. 3;
FIG. 5 is a perspective view wherein production of a fleece-utilizing apparatus ccording to the invention is depicted;
FIG. 6, FIG. 7 and FIG. 8 are, respectively, side elevation, top plane, and perspective 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 a perspective view, particially 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 schematic 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-0n 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 entrained 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 patterned crossing relation to form a felted fleece, and means for moving the form relative to the entrained, 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 passageways 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 can be mounted on a spinneret 12', with the spinneret holes 12, disposed for directing filaments to 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, above and below the spinneret holes 12, the issuing filaments are entrained as a plane of filaments extending substantiallly horizontally and directed toward the fleece form 14. The filaments pass between the secondary gas supply conduits 15. Gas discharging from the secondary air 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 can be a perforated cylinder and suction can 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 tobe arranged in a random and crossing relation on the form 14. Other means can be provided to break up the plane of filaments adjacent the fleece form 14, such as air supply means 38a and 38b which will supply air streams cutting across the path of the filaments to disrupt the plane thereof. Further, the guide passageway or channel 39 can 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 patternlike 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 perspective representation in FIG. 5, the filaments 21 are issuing from the spinneret hole 12 and are maintained in a plane by gas streams issuing from the gas discharge passageways 13 and 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 can be of any desired configuration and thus can be garment form.
As noted above, the spacing of the spinneret holes 12 forming the gas discharge passageways 13 can 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 communicates 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 receivethe 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 channel to the exit end thereof which is disposed adjacent the fleece form 45, which in the embodiment here illustrated is a screen. The guide passageways serve to prevent entanglement of filaments of one rank with filaments of another rank, 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 by suppressing turbulene allow 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 to apply its frictional force.
A screen 45 is moved in the direction of the arrow 50 (FIG. 8) 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 their interfelting the air channels 39 are 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 pinion 42, is provided for the rockin= action of the air channels, the turning point is located at 40.
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 of movement of the screen 45, indicated by the arrow 50 overlap each other. This can be best seen in FIG. 8.
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, and an air passageway 13 is disposed adjacent each row of spinneret holes and on each side thereof. Resin is supplied by conveyor 51 to the 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 can be a square chamber with a centrally disposed opening for passage of the filaments extending therethrough, and with a plate disposed adjacent filament path through the chamber on each side of the filament path. Openings can 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 for introduction into the openings 66 is introduced into 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 can be deposited in the fabric to provide a fabric having a wovenor knit-like pattern. This can 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 can best be accomplished by using a collecting screen or foraminous form, which on the places of mesh or holes of the woven or knit pattern have elongated guiding studs or pins. These studs or pins can 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 pyramical form provides narrowing air passage 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 difier 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 woven-like 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 more 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 provide the fabric form with 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 performations and guiding studs corresponding to the knit-like 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 wovenlike pattern, as is shown in FIG. 11, the surface on which the filaments are collected can 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 according to the invention has been found to provide a maximum uniformity of the fiber web over the entire width of the material and still having different drawing ratios of individual filaments. The swinging of the guide passageways provides for a method of determining the parallelism of filaments within given strands in woven or knit like patterns. The higher the swinging speed, the more unidirectional is the way of filaments within the strands while forming the mesh of wovenor 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 can 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 and entrain the filaments for a distance of at least 300 mm, and preferably 600 mm. without the individual filaments being entangled with one another by turbulance. The use of air channels enables the realizing of such results.
The great cross-sectional reduction produces an orientation of such filment molecules, and the finer the filament is drawn, that is, the greater the gas pull is, the greater the 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 ipun from polycaprolactam according to Example 1, he-
Table 1 shows how the fiber thickness varies with the rate of flow of polymer per spinneret hole, the gas currents remaining constant:
TABLE 1 Rate of flow per spinneret hole in Gas velocity in the Fiber thickness cot/min. slots in m./see. in microns Fineness in Tensile strength in in microns den-iers grams per denier 7. 5 0. 4 ti. 2 l 1. 0 l. .3. 4 l9. 0 2. U l. i) 22. 5 4. 5 1. 4
The curve in FIG. 9 shows the birefringence of polyamide-6 fibers in relation to fiber fineness. It IS apparent 10 of fiber characteristics obtained with various raw materials:
TABLE 3 Rate of fiow Velocity Fiber through of gas in Gas Spinneret strength, Fiber spinneret the sht, Temp, Temp., g. per thickness Polymer cc./m1n. m./sec. 0. C. denier in microns Polycaprolactam 1 70 260 240 3. 2 11. 5 Polypropylene 65 150 260 265 5. 0 8. 0 Polyethylene terephtha1ate 0.1 170 260 247 3. 5 13. 0 Polystyrene 065 180 375 248 1. 5 13. 0
from this that, in the case of fine fibers, birefringence EXAMPLE 1 values are achieved which correspond to those of normally spun and then drawn mechanically fibers in the cold state. If no special precautions are taken the flow 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 degrees of arr and polymer speeds for instance in the middle of the nozzle as compared to the ends of the nozzle, a characterist c which becomes especially dominant in long nozzles. ThlS results in the production of a spectrum of fiber thicknesses. It has been found that the birefringence of these different filaments increases with decreasing thickness, indicating increasing chain molecule orientation. Production of a uniform non-woven fleece is possible by swinging the guide passageways so that a given line on the collecting screen is served by several spinning holes. This difference in filament thickness can be avoided by having longer air slots than spinning rows in order to put the decrease in air speed to a place where no filaments are formed and by havlng smaller spinning nozzles. However, it has been found desirable having different filament characteristics within one fabric. The different thicknesses give a better closed surface. The thicker fibers have higher elongations because of lower drawing ratios and give the fabric a certain toughness, because when stress is applied they will elongate.
The felting of the individual filaments into a nonwoven fabric takes place on the basis of various principles. On the one hand, the spinning speed is substantially higher than the speed with which the fabric is taken out, the two speeds being in a ratio of approximately 100: 1. Thus, if the web of filaments is blown onto a screen belt with a suction behind it, the filament can be laid on in loops of a diameter always greater than 1 mm, i.e., greater than the filament spacing, so that adjacent loops overlap. Another factor that contributes to the felting is the turbulence of the gas current after leaving the guiding channels and striking the screen belt. The turbulence also increases as the deposit of fibers on the screen belt increases. The felting together of the ranks of filaments from different spinnerets is according to the invention brought about by swinging the guiding channels of passageways. The ranks of filaments follow the swinging movement without inter-twining inside of the channels. A frequency of as many as 3 to-and-fro movements per second is appropriate. In this manner, the point of deposit of a particular filament can be displaced several times per second into the area of the adjacent spinneret and back, so that a satisfactory inter-felting is achieved.
The bonding of the unwoven fabric thus produced can be brought about by various methods. The fi aments can be welded together by heat treatment or with the aid of swelling substances. Secondary bonding agents in the form of dispersions or solutions can also be added. The fabric can be needled. Particularly desirable eflects can be achieved by printing-on the bonding agents in certain patterns, because this especially preserves the inherent textilelike character of the goods. All fiber-forming polymers that can be melted without decomposition can be used as raw materials for the present process.
The following table gives a perspective of a number Granulated polyamide (polycaprolactam, melting temperature 210 C., relatively 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 material 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 at a distance of 0.4 mm. on both sides air slots of 0.2 mm. height, along its entire length. The continuous filaments passing from the nozzles in the form of broad, non-cohering parallel bands were each seized above and below by the air currents of 200 m./ sec. speed which were leaving the slots heated to 220 C. and pulled forward thereby. The filaments were thereby accelerated from a speed of 1 m./min. within the nozzle holes to about 1200 m./min. Within a distance of 3 mm. from the nozzle exit. In a distance of 30 mm. from the nozzle exit each row of filaments together with their air streams, which by now had a temperature of C., was brought into its air channel, which consisted of boxlike duets with the dimensions of 35 cm. width, 3 cm. height and 5 8 cm. length and which were open on the side which was opposite the nozzle (entrance) and on the outer side opposite the filament receiving screen (exit). Each nozzle had its own air channel, which kept the filaments from each nozzle separated as well as parallel. The air channels were rocked around an axis which was on the entrance side, so that it was swinging back and forth 5 cm. on the exit side and indicated on FIG. 8. The swinging of the 4 air channels was parallel. The filament rows were allowed to fly through the atmosphere for 30 cm. after leaving the air channels.
The flying was also in a swinging fashion since the air channels gave them their direction. They were finally collected on a moving screen which below had a suction device. The screen was moved forward with a speed of 10 m./min., while the 4 different rows of filaments coming from the 4 nozzles were interfelted to a cohering nonwoven fabric. The fabric was padded with a 30% disperslon of polyacrylate resin (Butyl acrylate) and dried, giving a fabric of 30 g./sq. meter fiber and 10 g./sq. meter bonding resin.
EXAMPLE 2 A granulate of polycaprolactam (red 2.28) was melted on a worm gear press, and fed by means of spinning pumps, at a temperature of 260 C. The spinning pumps circulated the melt to four spinnerets heated to 230 C. Each of the spinnerets consisted of a rectilinear line of holes, in number, and having a diameter of 400,u., spaced from each other at 2 mm. The row of holes was bounded on both sides at a distance of 0.4 mm. from an air slot 330 mm. in length, in each case, and air currents were forced out of the said air slot after being heated, to 230 C., at a rate of speed of 200 m./ sec. The filaments issuing from the holes were seized by the bilateral air currents and thrust forward, whereby at a distance of about 3 mm. from the spinneret they were accelerated from a rate of speed of l m./min. in the hole, to 1000 m./min. At a distance of 5 cm. from the spinneret the filament track of each individual spinneret was introduced into a lengthwise air-duct registering with it, the inner dimensions of said duct being about 3 x 35 cm. and having a length of 58 cm. Until the filaments entered into the air ducts, the air currents pertaining to each of the spinnerets had cooled down to 100 C. and maintain the filaments separated from each other. The air ducts assured that along the further path, the individual filaments also remained separated from each other, 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 air ducts were captured by 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 through hot air currents, 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 alternating directions of the endless filaments.
The unwoven fabric articles of the invention have a soft hand like woven or knit goods feel, and can, therefore, be used wherever woven or knit goods or other such interlaced fabrics are used at the present time. The new process, however, substantially simplifies the manufacture of such textile products, since the 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 avivage 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 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 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 for the adequate fixation of the staple fibers. The result 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 can be polymers such as polyamides, polyesters, polyolefines, polyvinyl acetate, polyvinyl chloride, polyvinyl alcohol, cellulose acetate or cellulose in dissolved form (viscose). These materials can be spun into continuous filaments by the melt or solution spinning process. In contrast to the prior art spinning methods, the process of the invention uses directed gas currents as drawing medium while spinning from several linearly arranged rows of holes and whereby each row has two air slots, and an air channel. The air channels on guide passageways have 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. Preferably, spinnerets are used which have more than 100 holes per spinning nozzle. The spinning speed can 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 fom above and below by a primary current of gas and accelerated, resulting in a reduction of the filament cross-section from, for example 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 do not ony 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 precipitate solutions of high polymers in filamentary form. The solidification of the filaments coming from the spinneret can also be accomplished by chemical action, by using acid vapors, for example, of xanthogenate solutions.
When the bands of filaments are collected, for example, by a screen with vacuum apparatus behind it, the individual filaments are superimposed 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 the strength, the fleece, for example, that has been formed from continuous filaments can 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 distlnguish themselves by a combination of high strength with a soft, pleasant cloth-like hand. Nevertheless, they can be further improved for the achievement of special properties. For example, it is possible to achieve woven fabric-like materials by calendering with embossed rollers; this gives the material a better hand and it can 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 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 can 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 can 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 can be made more ironable by tempering at elevated temperatures. A substantial improvement in launderability has been achieved by treatment 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 manterials. The advantage of the fibrous materials of the invention in this case is also and especialy the fact that the continuous filaments do not contain any avivage 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 taking place by spinning under oxygen atmosphere. It has proven surprising that, :when the fibrous materials of the invention are used, for example, for the improvement of artificial leather products, especially smooth, uniform materials are obtained.
Further, paper-like products can be produced from fleeces according to the invention. Suitable materials can 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 stifieners, 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 stilfeners 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 can 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 sufficiently low temperatures to the base cloth with a sufficient degree of adhesiveness, or because the adhering surface was not resistant to cleaning or washing.
On the other hand, polymers or polymer mixtures which can 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 sufiicient 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 can 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, which generally tend to breakage of the yarn, can be spun out without breaking to textile webs. Such air currents are in contrast to strongly eddying air currents which would snap off the spinning mass upon 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 can be fixed in such a manner that the layer of air closest to the filament at the outlet of the spinner (i.e. the initial velocity of the air), has more than times the velocity of the filament, preferably so that the speed of the filament commencing with the spinneret gains 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 the different layer levels. The oriented air currents render it possible to obtain a great elongation in the spinning and drawing ofcomplex mixtures, and also permit collection as webs of desired form. This is so also in the case of such fibers which will not withstand a normal carding process.
Apparatus as is described hereinbefore can be utilized for production of the iron-on stilfeners. Desirably the air jet above and the air jet below the filaments are oriented air currents, and the velocity in each can be such that the velocity in the stratum adjacent the filaments is highest, and the velocity decreases from stratum to stratum in the direction away from the filaments. Multiple slots or nozzles can be used to produce each air stream to facilitate obtaining the desired gradient in velocity. Upon issuing from the guide passageways, the filaments can be picked up with the aid of a suction device as is shown in FIG. 3 and can 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 can be resorted to. Generally such methods are preferred as do not require any additional binding agents, except where special effects are sought by means of binding or finishing means.
The iron-on fabrics of the invention can 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 say 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, can 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, can be porous since the fleece can 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-on can 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 seizing the melts issuing from the spinning holes and drawing 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 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 10 mm. from the spinneret. Commencing with a distance of 60 cm. from the spinneret, the filaments are captured by 1 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 zeaprolactam-and adipinous hexamethyiene diamine and,1 part of 2-ethyl-hexanol-para-oxybenzoic acid ester was melted in a Worm gear press at a temperature iof 130 C. The melt was supplied to a spinneret heated to 160 C. The spinneret was;mounted, as indicated in Example 3, but the air jets on leaving the slot,;exhibited a temperature of 160 C. The: air jets were produced with the aid of a pressure of 1.2 atm. on the slots. The fleece, produced in accordance with Example 3, exhibited an adequate initia i adhesiveness on reaching the screening drum to assure mutual consolidation of the fibers. e
- Z EXAMPLE 5 V 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 by means of a pressure on the slot of 1 atm. The fleece produced on the screening drum hy suction was consolidated by routing through rollers heated to 150 C.
The iron-on fleece cae be of any suitable weight for the task to be performed. Thus the weight can be sueh as to provide a desired stiffening eifect. Where the fleece is to serve mereiy the function of joining two webs to form a sandwich, the fleece can appropriately be light. The fleeces can be, for example, 5-50 grams per square yard, and;will commonly preferably be 5-25 grams per square yard. The fineness in denier can be in the order-of tenths and above,1for example 0.3 and above. As a range the denier can be about 0.3-5, preferably 0.5-3.
As to the composition of the monofilaments, this can be any one of a wide range of materials and mixtures. The composition should soften in the range of 110-180 C. and should 'be'forrnable 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, withput 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 mixturesof cellulose acetate with softeners.
While the invention has been described with respect to particular embodiments thereof, these various embodiments are merely representative of the invention and do not serve to set forth the limits thereof.
What is claimed is? 1: Process of producing a non-Weven fabric fleece stream cools said filaments.
which comprises'spinning from an elongated spinneret a polymer capable of being formed into fibers into at least one row of substantially parallel, substantialiy coplanar filaments; impinging a gasstream onto both sides of said, row of'filaments adjacent to said spinneret; passing atleast a portion of said gas stream and said filaments in a tacky state-through channel means adjacent to and longitudinally from said spinneret with said filaments spaced from the walls of said channel means and from each other, and depositing said filaments after such have left said channel means, onto 'a fleece form in random array, whereby said gas propels said filaments through said channel, elongates said filaments, and orients the polymenrnoleculs of said filaments betwee said spinneret and said channel means. i e
2. Process as claimed in claim 1; including spinnin a multiplicity of rows of filaments.
3. Process as claimed in claim 1, including impinging a secondary gas stream upon said filaments while said filamentsare within said channels. 1
4. Process as claimed in claim 1 wherein said filaments are drawn by said gas stream to reduce the diameter thereof in a ratio of at least abeut 30 to 1.
5. Process asclaimed in claim 1 wherein said gas 6. Process as claimed in claim 1, including heating said gas stream.
7. Process as claimed in claim 1, including applying suction means on the 'side of said fleece form opposite to the side thereof upon which said filaments are deposited, whereby aiding in the deposition of said filaments thereon.
8. Processas claimed in claim 1 wherein said polymer has a sofetning temperature in the range of about to C.
References Cited UNITED STATES PATENTS 1 DONALD J. ARNOLD, Primary Examiner Z us. c1Fx.R. ,l8'2.5; 51-296; 264-176, 290
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