US3833438A - Process for the manufacture of a non-woven web of continuous filaments through the wet stretch spinning method - Google Patents

Abstract

A plurality of filaments are extruded simultaneously from a large number of spinning orifices arranged in a rectangular pattern. The filaments are contacted by a coagulating bath as they pass downwardly through a funnel arrangement to cause stretching and coagulation of the filaments prior to depositing the filaments onto a moving pervious conveyor which is oscillated periodically in a direction transverse to its direction of movement.

Description

United States Patent [191 Kaneko et al.

[451 Sept. 3, 1974 PROCESS FOR THE MANUFACTURE OF A NON-WOVEN WEB OF CONTINUOUS FILAMENTS THROUGH THE WET STRETCH SPINNING METHOD [75] Inventors: Tutomu Kaneko; Takashi Turumi;

Shuichi Emori; Ken Ito, all of Nobeoka, Japan [73] Assignee: Asahi Kasei Kogyo Kabushiki Kalsha, Osaka, Japan [22] Filed: Aug. 30, 1972 [21] Appl. No.: 284,852

[52] U.S. Cl. 156/167, 156/181, 156/441, 264/87, 264/181, 264/182, 264/199 [51] Int. Cl D04h 3/16 [58] Field of Search 156/167, 181, 441; 264/87, 264/178 F, 181, 182, 195, 199; 425/71 [56] References Cited UNITED STATES PATENTS l/l936 Dreyfusu 425/71 2,289,657 7/1942 Knehe et a1 264/199 3,333,040 7/1967 Nakahara 3,441,468 4/1969 Siggel et a1. 3,689,620 9/1972 Miyazaki et a1. 3,705,068 12/1972 Dobo et a1. 156/167 Primary Examiner-Daniel J. Fritsch Attorney, Agent, or Firm-Sughrue, Rothwell, Mion, Zinn & Macpeak [5 7] ABSTRACT A plurality of filaments are extruded simultaneously from a large number of spinning orifices arranged in a rectangular pattern. The filaments are contacted by a coagulating bath as they pass downwardly through a funnel arrangement to cause stretching and coagulation of the filaments prior to depositing the filaments onto a moving pervious conveyor which is oscillated periodically in a direction transverse to its direction of movement.

4 Claims, 8 Drawing Figures PROCESS FOR THE MANUFACTURE OF A NON-WOVEN WEB OF CONTINUOUS FILAMENTS THROUGH THE WET STRETCH SPINNING METHOD This invention relates to improvements in and relating to a process for the manufacture of non-woven fabrics. More specifically, it relates to a process for the manufacture of a non-woven fabric made of continuous filaments, said filaments being spun in the wet stretch spinning process and then cast into a web in direct succession to the said spinning process.

With respect to a melt spinning process or dry spinning process, various and profound proposals have been made for the manufacture of non-woven fabrics in the form of webs made from continuous filaments, but, according to our knowledge, there has been made practically no technical developments in the field of the corresponding wet spinning process which would provide acceptable products on an industrial scale of production.

This kind of technical delay may be caused by the following facts. In the melt spinning or dry spinning process the medium around the spun filaments consists of gas, especially air, while that used in the wet spinning process consists naturally of liquid which has substantially higher viscosity in addition to the inherent surface tension. Therefore sufficient stretching and uniform distribution of the extruded filaments and formation of a web having relatively uniform distribution and intimate crossings is very difficult to realize technically.

The present invention has as its general object to provide a process for the industrial manufacture of nonwoven fabrics composed of wet spun continuous filaments devoid of aforementioned conventional drawbacks inherent in the utilization of the wet spinning process.

A specific object of the present invention is thus to provide a process for the manufacture of non-woven web composed of continuous filaments by the direct utilization of the funnel spinning and stretching process in the continuous wet spinning mode, said filaments being distributed in a substantially uniform way, yet having highly intimate crossing with each other.

A further object of the invention is to provide a continuous wet process for the manufacture of a nonwoven fabric web of the above kind, said web having superior strengths in the longitudinal, as well as lateral directions of the web.

For the realization of the aforementioned objects, the process according to the present invention comprises several steps in combination, namelyzextruding filaments simultaneously from a large number of spinning orifices generally arranged substantially in the outline form of an elongated rectangular, and subjecting them to a treatment of coagulation by contact with a coagulating bath liquid in a funnel wet spinning mode; stretchingand casting said fonned filaments together with the downwardly flowing coagulating bath liquid, onto a moving pervious conveyor into a fonn of a web; subjecting said travelling conveyor to lateral oscillations periodically in the direction perpendicular to the travelling direction of said conveyor, and subjecting the thus formed non-woven fabric web to scouring and further treatments while said web is being conveyed on said conveyor.

The said process may be carried out advantageously and preferably in the following way.

The spinning liquid which is wet-spinnable is extruded vertically and downwardly through a large number of extrusion orifices bored generally in a rectangular outline configuration through a rectangular nozzle plate, said nozzle plate being coupled with a rectangular funnel filled with coagulating liquid having at its bottom a horizontally elongated opening of a slit-like form, said extruded filaments being introduced in the form of a multiple filament curtain into and through a coagulating bath maintained within the interior space of said funnel and flowing through said bottom outlet opening downwards in the form of a multiple filament curtain accompanied by coagulating liquid having a form of a moving curtain in which said filaments are being distributed uniformly. The filament curtain is subjected to a proper coagulation and stretching effect by being accompanied by said downflowing liquid curtain through and by said slit-like outlet opening and finally cast into a continuous web onto a travelling pervious conveyor which is subjected, however, continuously to lateral oscillations in the direction perpendicular to the travelling direction of said conveyor for the purpose of letting these filaments in the web be dropped in a neatly and well-distributed interlace texture formation. Below the filament casting position on the conveyor, there is provided a suction box in close proximity to the underside of the pervious conveyor, so as to suck the coagulation bath liquid through the meshes or perforations of the conveyor, for suppressing an accumulation of the bath liquid that impinged against the conveyor and a substantial lateral flow of the otherwise accumulated liquid flow. The thus shaped non-woven web made of continuously wet spun filaments neatly interlacedwith each other is then subjected to a conventional scouring and further conventional after-treatments known per se.

These and further objects, features and advantages of the present invention will become more apparent when read the following detailed description of the invention by reference to the accompanying drawings illustrating substantially schematically a preferred embodiment of the apparatus adapted for carrying out the process according to this invention, and to several preferred numerical examples of the said process.

In the drawings:

FIG. 1 and FIG. 1a are a schematic side elevation of a plant adapted for carrying out the process according to this invention, as applied to a cuprammonium spinning process, wherein, however, the drawing has been prepared into separated two parts which parts should be joined together by overlapping the separation lines X-Y with each other.

FIG. 2 is a schematic perspective view of a rectangularly arranged spinning nozzles/funnel-combination unit employed in the plant shown in FIG. 1, a large number of extruded filaments therefrom, forming a multiple filaments curtain, and a continuously travelling pervious conveyor subjected to lateral oscillations periodically. Wherein, however, said liquid curtain has been omitted from the drawing for avoiding complexity thereof.

FIG. 3 is a schematic plan view of a mechanical driver for the lateral oscillation of the pervious conveyor.

FIG. 4 is a diagram for the illustration of the moving mode of the pervious conveyor.

FIG. is a perspective view of the spinning funnel assembly wherein said assembly is partially broken away for clear representation of inner operating parts.

' FIGS. 6 and 7 are two schematic sectional views of still further improved spinning funnels.

In the drawings, numeral 1 represents a plurality of inlets arranged in a row and connected to a supply source, preferably, a reservoir tank, not shown, of a spinning liquid, preferably cuprammonium solution, and kept in fluid communication with the interior space of a hollow nozzle box 2 which has a generally a rectangular plan view shape, as may be most clearly seen from FIG. 1. Although not shown a large number of extrusion orifices are bored vertically through the bottom plate of said nozzle box 2.

As an example, in a specific embodiment of the funnel spinning unit, 90 X 1,000 (thus, totally 90,000) orifices, not shown are arranged in a generally rectangular outline configuration. Each of these orifices may have a bore of 0.8 mm, and a mutual pitch of 1.5 mm. However, two or more different-bore sizes may be combined together, when necessary.

On the other hand, a coagulation bath liquid, preferably deaerated soft fresh water in the cuprammonium solution is fed from a certain reservoir tank, not shown, through proper piping means, not shown, to inlets 5, thence being conveyed to the interior of a stationary bath vessel 4, said nozzle box 2 being fixedly mounted on and passing through the top plate 4a of the vessel 4. At an intermediate level in the interior space of the bath vessel 4, there is provided a vertically perforated rectifier plate 3 fixedly attached to said vessel, although the fixedly attaching means have been omitted from the drawing only for simplicity.

Directly below the nozzle box- 2, a spinning funnel 6, having a V-shaped cross-section, is arranged so that its upper and larger inlet opening 6a is positioned at a relatively high level above the rectifier plate 3 and directly below said nozzle box 2 and within the interior space of the bath'vessel 4. The lower half of the funnel 6 protrudes downwards from inside to outside of the interior bath space of the vessel 4, a slit-shaped outlet opening being formed at 7 of said funnel.

When spinning pump in the aforementioned spinning liquor supply source is operated, 1,000 fine filaments are extruded in this case from the aforementioned extrusion orifices into the bath chamber within the vessel 4 which is now filled with the coagulation bath liquid from below through said inlets 5. The bath liquid is conveyed in an overflowing way to the upper large inlet opening 6a substantially in a laminar flow after passage through rectifier plate 3. Then, the bath liquid will flow substantially with a static water head through the grad-v ually reducing flow passage accompanying the extruded filaments which gradually converging and finally and forcibly arranged into a single filaments curtain 3, as most clearly seenfrom FIG. 1'. Although not shown, the bath liquid is discharged from the coagulation bath chamber through the slit-like outletopening 7 and in the form of a liquid curtain. The liquid curtain envelopes the filaments curtain positioned at the center thereof when seen in the cross-section of the former curtain now flowing downwards practically in the form of laminer flow. During this accompanied flow 'of the filaments curtain, the filaments are subjected to a proper degree of coagulation and are stretched several times under the influence of downflowing and enveloping streams of the funnel bath liquid. While the filaments take the shape of a kind of curtain wall, the bath liquid flows in the shape of a laminer flow, so as to provide a liquid curtain wall.

Thethus formed filament curtain 8 is cast on a pervious conveyor 9, preferably a wire net, travelling continuously at a constant rate in the direction of arrow A and at the same time being subjected to a lateral oscillation as shown by another arrow B, so as to form a continuous web, while the down-flowing liquid curtain will impinge against the conveyor.

At the position at which the filaments curtain and the liquid curtain impinge upon the conveyor and directly therebelow, there is provided a suction box 10, so as to 'suck the impinged water for the prevention of accumution as shown by another arrow B, as was referred to above.

Although the driving mechanism can be designed in various ways, so far as the conveyor 9 is subjected forcibly to lateral oscillations in the direction perpendicular to the advancing direction thereof, it is highly advantageous to use a mechanical oscillator device as mainly shown by way of example in FIGS. 2 and 3.

In these Figures, numeral 11 denotes a frame member, the main part thereof being arranged horizontally and substantially in physical parallel relation to the lower travelling run of said conveyor 9 and laterally slidably mounted on a frame assembly 12 for the whole plant, said assembly being shown only partly in its plan view in FIG. 3.

Roller 13 is rotatably mounted through its bearing means 14 on the oscillator frame 1 1 and a further roller 15 is mounted rotatably by means of bearing means 16. Oscillator frame 11 also supports the suction box 10.

' By the rollers 13 and 15 which cooperate with a further roller 17 and a drive roller 18, the conveyor 9 is mounted properly in its tensioned state. The drive means for the drive roller 18 has been omitted from the drawing only for simplicity.

As was referred to hereinbefore, when the whole plant is operated, conveyor 9 is brought into its travelling state in the main direction shown by arrow A, while the rear portion of said conveyor 9 situated below the coagulation bath vessel 4 is forcibly subjected to lateral oscillationsperiodically, as shown by arrow B. For execution of such lateral oscillation, the drive mechanism is used which is shown in its plan view in FIG. 3.

In FIG. 3, numeral 19 denotes schematically a drive motor, from which rotation will be transmitted through meshing gears 20;21 to crank rod 22 which is attached eccentrically to said gear 21 so as to perform a crank motion.

One. end of said rod 22 is pivotably connected through a pivot pin 24 to the free or outer end of a further rod 23, theinner end of the latter rod 23 being fixedly attached to the oscillator frame 11. In this way, the oscillator frame 11, together with rollers l3;l5,

conveyor 9 kept in tension by these rollers and a suction box 10 mounted on said oscillator frame, are subjected to periodic lateral oscillations in the direction shown by arrow B. As was referred to hereinbefore, the oscillator frame 11 is mounted on the frame assembly 12 of the whole plant and subjected thereon to lateral oscillations. The frame assembly when sectioned partially along by a section line E-E in FIG. 3 represents a L-shaped cross-section and rollers rotatably mounted on the oscillator frame 11 are rotatingly guided on horizontal webs of said L-shaped frame parts, while rollers 26 which are also rotatably mounted on the vertical webs of said L-shaped parts, so as to guide jointly the oscillative frame 11 in a highly convenient and optimum manner.

In describing the movements of said conveyor, the desired formation of the web of continuous filaments will be explained in combination therewith.

As will be seen from the foregoing, the conveyor 9 performs a sinusoidal movement, as schematically illustrated in FIG. 4.

According to our experiments, the strength. of the nonwoven fabric web as formed on the conveyor 9 depends upon the relative ratio between the half amplitude a and half wave length I. More specifically, the smaller the ratio: a/l, the longitudinal strength of the web will be larger. On the contrary, with larger values of the ratio a/l, the lateral strength of the web will become higher.

Based upon the foregoing general knowledge and based upon our experimental results, it has been found that when the ratiora/l lies between 0 3.0, preferably 0.5 1.5, the longitudinal as well as the lateral strength of the web represents a reasonable value in an acceptable degree, in addition to the desired superior interlace structure. In addition, the amount of applied filaments amount per unit area of the web was very evenly distributed over the entire surface area of the web.

Since the suction box 10 is caused to laterally oscillate with the same amplitude and in phase with the conveyor, the web structure on the conveyor will not be appreciably disturbed.

When necessary, two or more rectangular funnel spinning units could be arranged in parallel to each other with equal results.

A salient feature of the manufacturing process according to this invention resides in the use of the spinning step by use of a rectangular spinning funnel. In practice of the invention, it is absolutely necessary to induce in the filaments as uniform as possible stretching, and indeed, without disturbing the flow of a large number of the wet spun filaments, One of the necessary conditions may reside in the use of the practically laminer flow of the coagulation bath liquid through the spinning funnel after being subjected to a rectifying action. During this course of operation, the coagulation bath liquid causes by its inherent viscosity the nonsolidified spun filaments to stretch downwards. The rate of stretching in this case may be modified by alteration of the velocity of the downflow of the bath liquid. However, in a preferred embodiment of the process according to this invention in the case of cuprammonium process, the liquid flow velocity as measured at the outlet opening of the spinning funnel amounted as high as 100 m/min and the draft or stretch ratio was found as high as about 400 percent.

A further feature of the process according to this invention resides in the lateral and periodical oscillation of the pervious conveyor in the direction perpendicular to the travelling direction of the conveyor, whereby the fonnation of an intensified interlaced texture and in a substantially uniform rate over the whole length of the web as well as over the whole width thereof will be substantially accentuated.

Before attaining the technical idea for adoption of the above kind of lateral oscillation of the pervious conveyor, we have tried and experimented in various other ways. Among others, the air jet process as was normally adopted in the manufacture of non-woven fabric webs in the utilization of dry or melt spinning process were tried and experimented. However, it was found that in sharp contrast to the gaseous medium which is commonly utilized in the dry or melt-spinning process, the use of liquid spinning medium as the spinning one and the very presence of the relatively high viscosity and the surface tension owned by the liquid, was disturbed to a substantial degree by the employment of the air or liquid jet process. According to our experiments, it was impossible to improve the degree of interlacing of the filaments and the even distribution of the filaments over and throughout the whole area of the web at the same time with each other.

For avoiding such difficulty and for improving the quality of the web in the above sense, the employment of lateral oscillation of the pervious conveyor was found highly effective for the desired purpose.

A still further feature of the invention will appear more apparent, when it is applied to the cuprammonium spinning process. More specifically, the coagulation velocity of the spun filaments is properly adjusted by the adjustment of the coagulating power of the spin ning bath liquid and in addition, the working pressure at the pressure rolls 27, so as to realize the web without use of any special bonding agent, but relying exclusively upon the self-adhesive power of the filaments as wet spun and, indeed, under proper adjustment of such self-bonding power of the filaments.

The after-treatment steps downstream of the web formation, may be scouring, drying, bonding agent application (when necessary), mechanical and other socalled secondary steps as known per se, for the purpose of the regeneration of the web as spun and formed in the previously mentioned way. In FIG. 1, several examples thereof have been shown only schematically and by way of example.

Numerals 27;28 represent pressure rolls and 29;30 represent acid pickling, rinsing or chemical treatments which can be expressed generally as scouring and afterfinishing steps. Numeral 31 represents a drying step and 32 represents a winding step.

Although the present invention can be applied to any one of the known processes in the mode of the wet and funnel spinning mode, a maximum advantage was found in the case of the invention as applied to the cuprammonium spinning process. In this case, the produced web showed a favorable and even distribution of the filaments in the web and with intimate and profound interlaced texture of the filaments, in addition, the web may have substantially equal degrees of strength in the both, longitudinal and lateral directions of the web.

As for the after-treatments, the invention can not be limited to the aforementioned specific embodiments.

Various changes and modifications may easily occur to any person skilled in the art without departing from the spirit and gist as revealed in the appended claims.

In the following, two preferred numerical examples of the invention will be given for better understanding of the subject matter of the present application.

' EXAMPLE 1 I By use of cuprammonium filaments, a non-woven web was manufactured in the mode as was illustrated in the foregoing in connection with FIG. 1.

The nozzle plate was bored with 90 rows in the advancing direction of the pervious conveyor and 1,000 rows in the direction perpendicular thereto, of extrusion orifices, each of 0.8 mm, the pitch being at 1.5 mm. The spinning liquor was extruded 0.05 g/min per orifice. The coagulation bath liquid was deaerated soft fresh water and supplied at 120 lt.'/min. The outlet slit of the funnel has a width of 5 mm. The pervious conveyor was situated at 50 cm below the said bath outlet slit opening. The cast filaments had each 1.3 denier. The strength of the filaments amounted to each 2.1 g per denier. The pervious conveyor was a wire net made of vinylidene chloride, of 24 meshes.

The net conveyor was advanced at a speed of m/min, and subjected to 200 lateral oscillations per minute by use of the oscillation device as shown in FIG.

3 in its plan view, and in the direction perpendicular to the advancing one of said conveyor. Under these conditions, the ratio: a/l, was 0.8. The impinged bath liquid was sucked through the net from below by a sucker which was held at a negative pressure of 700 mmHg.

The cast and formed web on the conveyor net was subjected to a scouring step while being conveyed on the net, then pressed between and by pressure roll pairs and finally dried and wound up. r

In this way, a web of non-woven fabric was obtained, representing a specific weight of 25g/m and showing a neat, uniform and well interlaced texture. This web showed substantially equal longitudinal and lateral tensile strengths. Physical properties of this web, in comparison with a similar product as reference, which was produced-under subjected no lateral oscillations to the net conveyor, will be shown in the following Table.-

In the similar way, yet=with an increased rate of delivcry of the spinning liquor to 0.1 g/min. per orifice, the wet spinning was carried out. The lateral oscillation of the pervious conveyor was same as in the foregoing Example In this way, a superior web of wet-spun, continuous filaments was prepared at a specific mass weight of 50 g/m This value was evenly distributed substantially over and throughout the whole area of the web.

Next, referring to FIGS. 5 and 6, a modification of the wet spinning funnel assembly adapted for better realization of the process according to this invention will be described hereinbelow in detail.

In these figures, numeral 103 represents a horizontally elongated rectangular outer casing of box construction within which there are provided an upper coagulation bath funnel 104 and a lower coagulation bath funnel 105 combined rigidly with each other in a vertically overlappingrelationship. The larger width portion of the upper bath is denoted with 106 and the smaller width portion of the same bath is denoted with 107. The lower bath funnel 105 is formed with a slit-like outlet 108. Although in these figures and in FIG. 7, a twostage funnel combination is illustrated, more numerous stage type funnel combinations may be adopted with similar effects, although not shown.

Numeral 109 represents a plurality of inlets for sup- "most end of the upper funnel 104 at a constant static head and is subjected to secondary rectification by contact with a pair of stationary rectifier plates 111 attached to the uppermost part of said upper funnel 104. It will be seen that from these FIGS. 5 and 6, there is formed a. downwardly and inwardly directing slit-like flow passage formed by and between each of said upper rectifier plates 111 and the upper funnel 104, and extending the lateral direction of the web to be formed, as will become more apparent as the description proceeds.

By the provision of these upper rectifier plates in close proximity to the uppermost extremity of the upper funnel and of the thereby formed slit-like flow passage directing downwardly and inwardly, fear of strong flows of the bath liquid brought into direct contact with the extruded filaments from the extrusion orifices, not shown, formed through the bottom of nozzle box 102 which is similar in its structure and function as those of thatshown at 2 in the foregoing, can be positively prevented.

A plurality of inlets 112 are provided through the bottom 118 of said outer casing 103 for supply of coagulation bath liquid from the supply source, not shown, under pressure, into the lower side bath defined between the intermediate separater wall 117 and the bottom wall 118 and within the lower part of said outer casing 103.

The supplied bath liquid through the inlets 112 impinges upon lower rectifier plates 113 and'fills up the lower bath upon flow through upper rectifier plate 114 in the form of a perforated one having a number of perforations 115. Upon filling-up of the lower bath, the secondarybath liquid will flow in an overflowing manner at a constant static head into the second spinning funnel 105.

It will thus be seen that with use of the double funnel type spinning unit so far shown and described the bath liquid feed rate (which may be expressed by V1) to the first bath and that (which may be expressed by V2) may be separately selected from each other, and in this way, the inner stresses of the filaments may be made larger than the agitating force by the bath liquid flow, as will be more fully described hereinafter.

In a modified double funnel assembly shown in FIG. 7, a plurality of inlets 119 are formed at the bottom wall 118' of the outer casing 103 for supply of the coagulation bath liquid from its supply source, not shown, and under pressure. Each of these inlets 119 is provided with a lower rectifier plate positioned stationarily in close proximity thereto. Within the interior of the casing 103', rectifier plates 121 and 122 in the form of perforated plates are provided and arranged in two stages. The fed coagulation liquid from the inlets 119 impinges upon respective rectifier plate 120 and then fills up the interior space of the casing upon passing through the two- stage rectifier plates 121 and 122, thence flowing in two stage flows into the upper and lower, overlappingly arranged funnels 104 and 105', respectively.

In this case, the respective flow rates V1 and V2 may be adjusted by proper selection of the respective opening degrees at the inlet parts 124 and 123 to the upper and lower funnels upon execution of slight and prior trial-and-error experiments.

The coagulation bath liquid will flow from the interior space of the outer casing 103 through respective inlets 124 and 123 into the upper and lower funnels 104' and 105, respectively, as was referred to above;

thence through the respective inside flow passages thereof. Since these funnel passages have gradually reducing cross-section when seen from upper to lower, yet maintaining the initial width as measured in the lateral direction of the web to be manufactured, the flowing speed will gradually increase. Naturally, the bath liquid is adjusted in its temperature in advance of its introduction into the casing 103 so as to'let the spinning liquid upon extruded from the nozzle box 102' and upon contact with the bath liquid, coagulate to a proper degree. It is a requisite condition to set the outlet flow rate at the lower end outlet of the upper or first stage funnel 104 substantially equal to or slightly higher than that appearing at the lower end outlet of the lower or second stagefunnel 105. In this way, the extruded and properly coagulated filaments, not shown in FIG. 7, are subjected to tension for increase of the internal stresses and so as to possess a counter-acting performance against the agitating force provided by turbulent bath liquid flow. In this way, the filaments upon extruded in a neat and geometrical arrangement having a laterally (of the web) elongated rectangular outline are enveloped by and within the down-flowing bath liquid and maintain its thick curtain without inviting entanglement among the down-flowing filaments while being subjected to coagulation and stretching.

Upon flowing through the gradually decreasing flow passages of the upper and lower funnels, while enveloping the filaments, the bath liquid is discharged from the slit-like outlet 108 of the second stage funnel 105', while enveloping the filaments therein. The thus discharged bath liquid flow from the slit outlet 108 or 108 into open air will take the form of a sheet-like one keeping the original lateral length and thickness substantially unchanged and including the fil-' aments curtain enveloped therein.

EXAMPLE 3 Cuprammonium spinning liquid was used for forming a non-woven web in the manner as was shown and described in FIG. 1. In this case, however, a double funnel spinning unit, as shown in FIGS. 5 and 6 was used.

The Cuprammonium liquid was prepared with conventional way, containing a cellulose concentration 10.0 wt. percent, ammonium concentration 7.0 wt. percent and copper concentration 3.6 wt. percent, and was extruded in the manner shown and described by reference to FIGS. 5 and 6 in the foregoing, while, as the coagulation bath liquid, de-aerated soft water was supplied through inlets 109 and 112, and fed to the upper and lower funnel baths in overflowing manner.

The nozzle plate was formed with X 10,000 rows of extrusion orifices when seen in the advancing and lateral directions of the web to be formed. The extrusion orifices had each 0.8 mm diameter and arranged at a regular pitch of 1.5 mm.

As for the flow-rate of the de-aerated soft water acting as the coagulating bath liquid, V was selected to lit/min (temperature: 34 C), while V was set to lit/min (temperature: 46 C).

In this way, the extruded filaments group was kept in contact with the down-flowing bath liquid and enveloped therein, as was mentioned hereinbefore. These filaments were subjected to coagulation and stretching. The lowest outlet opening formed at the bottom end of the second funnel had a width. of 5.0 mm, while its length as measured in the lateral direction of the formingweb had a value enough covering the width of the web, so as to form a slit-like outlet opening as preferred hereinbefore.

In this way, a curtain-like clear and transparent sheetlike flow was formed. At this stage, the outlet flow rate as measured at the slit-like outlet amounted to l 10 m/min. This sheet-like liquid flow contained no air bubbles and kept in a neat and clear laminar flow, without indication of flow turbulence. And the filaments were grouped in a neat curtain-like condition and totally enclosed within the liquid curtain in an evenly distributed manner without formation of any filament entangle ment. This liquid curtain containing therein the curtain-like condensed filaments arrangement, was led to pass through open air atmosphere until it impinged upon an advancing pervious net conveyor positioned at a lower level, distant 500 mm below from the slit-like outlet. The feed rate of the conveyor amounted to 10 m/min. The conveyor was made of a vinylidene chloride net, having 24 meshes. Below the pervious conveyor, there was provided a suction box, providing a negative pressure of 700 mmHg when measured at the level of the conveyor. In this way, the liquid flow including the filaments curtain was subjeced to a strong sucking action. Thus, a non-woven web made of continuous filaments was cast continuously on the net conveyor, said web had an even distribution of filaments. The denier of the filament in the web amounted to 1.3 denier in the strength being measured to 2.1 g/denier.

EXAMPLE 4 Acrylonitrile 94 wt. parts. acrylamide 5.5 wt. parts, allylsulfonic acid 0.5 wt. part, ammonium persulfate 4 wt. parts and thioglycolic acid 0.2 wt. part were dissolved in 1,000 wt. parts of water previously adjusted its pH value to 3.0 by addition of sulfuric acid, and polymerized at 60 C for 5 hours. The polymer was introduced at C into 70 percent-nitric acid so as to provide a solution containing 12 wt. percent of the polymer.

This spinning solution was spun, stretched and cast as before into a non-woven web. The funnel assembly was similar to that employed in the foregoing Example 3.

The extrusion orifices had each a diameter of 1.0 mm, the pitch amounting to 2 mm, and arranged in 20 rows when seen'in the advancingdirection of the net conveyor and in 150 rows in the perpendicular direction relative thereto. Asithe coagulation bath liquid, 37 percent-nitric acid aqueous solution was used. Ratio of V V was set to 1:1. Temperature of first bath flow representing at V was 1 C. That meatured at V was 3 C.

The spun-out filaments and the coagulation bath liquid enveloping therein these filaments were led to flow through the double-funnel system as before, for subjecting the filaments to coagulationand stretching, and then discharged from the slit-like outlet provided at the bottom of the double-funnel and having an effective discharge width of 2.0 mm, in the form of a clear, transparent and sheet-like laminar flows upon a net conveyor advancing at a velocity of 3 m/min. In this way,

a non-woven web, consisting of continuous filaments highly envenly distributed therein.

EXAMPLE 5 A viscose spinning liquid, having a cellulose concentration 8.4 wt. percent, alkali concentration 6.5 Wt. percent, mean polymerization degree 290, gamma value 55, viscosity 53 seconds, was prepared in the conventional way. This spinning liquid was spun, coagulated, stretched and cast into a non-woven web in the similar way as in Example 3.

.Each of the extrusion orifices had a diameter of 0.1 mm. These orifices were arranged in 1.5 mm pitches and in a rectangular arrangement of 30 X 200 rows.

The composition of the coagulation bath was: sulfuric acid 130 g/lit., and sodium sulfate 300 g/lit., and zinc sulfate g/lit. The ratio: V /V was set to 1:1. Temperatures at V and V were measured at 40 C and 60 C, respectively.

In this way, the spun-out filaments were coagulated, stretched and cast as before into a non-woven web. The width of the outlet of the double funnel was 2.0 mm. The advancing speed of the net conveyor was set to 3 m/mm. The web showed a highly even distribution of the filaments.

The embodiments of the invention in which an exclusive property or privilege is claimed are as follows:

1. A process for the manufacture of a non-woven fabric web of continuous filaments by way of a funnel spinning and stretching method comprising the combina- I tion of: v

extruding a spinning liquid through a large number of extrusion orifices arranged in a rectangular pattern to form a substantially planar filament curtain; subjecting the filament curtain to coagulating and stretching treatment by enveloping the curtain in a coagulation bath liquid; successively casting the thus'formed and stretched filament curtain along with the liquid directly onto a travelling pervious conveyor;

subjecting said conveyor to lateral oscillations in the direction perpendicular to the travelling direction of said conveyor while said web is being conveyed by and on said conveyor; and

subjecting the filaments of said web on said conveyor to conventional scouring and further aftertreatments. 2. A process for the manufacture of a non-woven fabric web composed of wet spun filaments prepared through a conventional wet spinning method, as set forth in the foregoing claim 1, said process further comprising;

introducing a coagulating bath liquid into a coagulating funnel in an overflow manner and at a constant static head; and I guiding said bath liquid through a funnel passage having a gradually reducing cross-sectional flow area as the flow descends, together with said spun filaments, said bath liquid flowing in a rectified and undisturbed state substantially in the form of a curtain wall enveloping said filaments which are finally arranged substantially in a filament curtain.

3. The process as claimed in the foregoing claim 2, further comprising subjecting a suction box arranged below said conveyor to lateral oscillations having equal phase and amplitude with the those of the lateral oscillations of said conveyor.

4. A process for the manufacture of a non-woven web of continuous filaments through the web stretch spinning method as set forth in the foregoing claim 1, said process comprising the following steps of:

extruding a large number of filaments of a spinning solution through a corresponding number of extrusion orifices arranged substantially within an elongated rectangular area and bringing these extruded filaments into contact with a flowing coagulation bath liquid in a coagulation zone for coagulation and stretching;

supplying to said coagulation zone consisting of at least a two stage funnel-shaped flowing bath, a co- 1 agulation bath liquid with laminar flow to each casting these wet-spun, coagulated and stretching filaments arranged in the form of a vertical curtain, together with a sheet-like flow of the coagulation bath liquid discharged from said zone and enveloping said filament curtain, onto an advancing pervious conveyor.

UNITED STATES PATENT OFFICE CERTIFICATE CORRECTION I Patent 8 4 8 Dated September 3, 1974 Inventor-(s) Tutomu Kaneko et al identified patent ppears in the aboveelow:

It is certified that error a hereby corrected as shown b and that said Letters P atent are IN THE H EADING:

The claimed Priority Data was omitted. Should read: August 3o;1'971 Ja a'nu n......;.66431'/1971- 3, I J p riiI. lIIIIlIlI5 9 I Signed and sealed this 19th day of November 1974.

l 1 (SEAL) Attest:

McCOY M. GIBSON. JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents R PC4050 useoMM-oc scan-pea I i U. 5. GOVERNMENT PRIN ING OFFICE I," 0-35-33.

Claims (3)

1. 2. A process for the manufacture of a non-woven fabric web composed of wet spun filaments prepared through a conventional wet spinning method, as set forth in the foregoing claim 1, said process further comprising; introducing a coagulating bath liquid into a coagulating funnel in an overflow manner and at a constant static head; and guiding said bath liquid through a funnel passage having a gradually reducing cross-sectional flow area as the flow descends, together with said spun filaments, said bath liquid flowing in a rectified and undisturbed state substantially in the form of a curtain wall enveloping said filaments which are finally arranged substantially in a filament curtain.
2. 3. The process as claimed in the foregoing claim 2, further comprising subjecting a suction box Arranged below said conveyor to lateral oscillations having equal phase and amplitude with the those of the lateral oscillations of said conveyor.
3. 4. A process for the manufacture of a non-woven web of continuous filaments through the web stretch spinning method as set forth in the foregoing claim 1, said process comprising the following steps of: extruding a large number of filaments of a spinning solution through a corresponding number of extrusion orifices arranged substantially within an elongated rectangular area and bringing these extruded filaments into contact with a flowing coagulation bath liquid in a coagulation zone for coagulation and stretching; supplying to said coagulation zone consisting of at least a two stage funnel-shaped flowing bath, a coagulation bath liquid with laminar flow to each stage; casting these wet-spun, coagulated and stretching filaments arranged in the form of a vertical curtain, together with a sheet-like flow of the coagulation bath liquid discharged from said zone and enveloping said filament curtain, onto an advancing pervious conveyor.

Images