US3293116A

US3293116A - Method and apparatus for making continuous webs from continuous filaments

Info

Publication number: US3293116A
Application number: US419248A
Authority: US
Inventors: Opderbeck Fritz; Ploetz Theodor; Scheuring Ludwig; Kirchner Ulrich; Berger Dieter; Wilken Ludwig
Original assignee: Feldmuehle AG
Current assignee: Feldmuehle AG
Priority date: 1963-12-20
Filing date: 1964-12-17
Publication date: 1966-12-20
Anticipated expiration: 1983-12-20
Also published as: SE319376B; FI43672B; DK115373B; NL6414689A; GB1084777A; LU47620A1; BE657343A; CH502469A; CH1605064A4; DE1461092A1; CH503837A

Description

Dec. 20, 1966 F. OPDERBECK ETAL 3,293, 4 METHOD AND APPARATUS FOR MAKING CONTINUOUS WEBS FROM CONTINUOUS FILAMENTS INVENTORS FRITZ OPDERBECK THEODOR PLOETZ United States Patent Ofi [ice 3,293,116 Patented Dec. 20, 1966 Claims. (Cl. 162216) This invention relates to the manufacture of paper and paperlike sheet products, and particularly to the manufacture of continuous webs which consist mainly or entirely of continuous filaments.

It is known to produce paper-like sheet materials from staple fibers and similar filamentous material of relatively short finite length, but the use of continuous filaments in paper-like material has been limited to bank note paper and similar applications in which the filaments do not in themselves constitute a self supporting web, but are individually or spacedly inserted in a load bearing web constituted mainly by fibers of limited length, typically not more than ten millimeters.

Even fibers twenty millimeters long cannot readily be converted into a paper-like product on conventional paper making machinery. They can be deposited only from very dilute stock, and the individual fibers must be relatively thick because thin fibers tend to agglomerate, and the paper produced tends thereby to show -a defect known as cloudiness. The usual synthetic staple fibers cannot form the basic, load-carrying structure of a web produced on the traveling screen in a conventional papermaking machine if their length is substantially greater than 40 millimeters.

Yet, it is well established that the strength and other important properties of paper-like sheet material improve with the length of the constituent fibers. Some of the valuable properties of continuous filaments in paper-like material have heretofore been utilized by embeddingthe filaments in a paper structure consisting mainly of the usual short fibers. The continuous filaments in the known materials are not interengaged with each other to constitute the load-carrying sheet structure. They must therefore be bonded to the shorter fibers, and a bonding agent is a necessaryingredient of the known products. The strength of these products is often limited not by the strength of the continuous filaments, but by that of the bonding agent.

The principal object of the invention is the production of paper-like sheet material in which continuous filaments constitute the sole or principal load-bearing elements, and are interengaged in such numbers that they constitute a self-supporting web.

A more specific object is a method of producing continuous self-supporting webs mainly constituted by interengaged continuous filaments.

Another object is the manufacture of a paper-like sheet material which consists of interengaged load-bearing continuous filaments and shorter fibers with a minimum of or without a bonding agent.

A further object is the production of paper-like sheet material which consists mainly of very fine continuous filaments, yet is free from cloudiness.

An additional object is the provision of apparatus for performing the afore-described invention.

With these and other objects in view, the invention, in one of its aspects, resides mainly in a method in'which a foraminous support such as a Fourdrinier screen is moved at a predetermined speed in a direction substantially parallel to one of its major faces. A liquid carrier is caused to flow continuously and transversely to the screen move ment from a feed area remote from the screen to a deposition area adjacent the same. The flow velocity of the carrier in the feed area is substantially greater than the speed of the screen, and decreases from the feed area toward the deposition area. A multiplicity of continuous filaments are continuously fed to the carrier in the feed area at a feeding speed which is higher than the speed of the screen, but lower than the flow velocity of the carrier in the feed area, whereby the filaments are elongated. in the direction of flow in the feed area. Respctive portions of the filaments are interengaged with each other While moving toward the support, and the interengaged filaments are deposited on a major face of the support. The engaged filaments are suflicient in number to form a self-supporting web on the support face.

In another aspect, the invention also resides in an apparatus for carrying out the method which includes a screen means for moving the screen in a path parallel to a major face thereof at a predetermined speed. A conduit is arranged so as to have an orifice directed toward the screen face in a portion of the path of the screen. Means are also provided for feeding a multiplicity of filaments longitudinally into a feed portion of the conduit remote from the orifice at a feeding speed substantially greater than the speed of screen movement. Discharge means discharge the filaments from the orifice toward the screen face at a speed smaller than the feeding speed.

Ultimately, the invention in yet another aspect also resides in the product formed by the method, namely in a continuous elongated fiber web which mainly consists of a multiplicity of randomly arranged, continuous, interengaged filaments.

Other features and many of the attendant advantages of this invention will be readily appreciated as the same become 'better understood by reference to the following detailed description When considered in connection with the accompanying drawing in which FIG. 1 shows a portion of a paper-making machine in elevational section; and

FIG. 2 shows the apparatus of FIG. 1 in plan view.

The illustrated machine is similar to that disclosed in the co-pending application Serial Number 189,778 filed on April 24, 1962, now United States Patent No. 3,190,790, and those elements of the machine not specifically illustrated in the drawing will be understood to be analog-ous to the apparatus disclosed in the earlier application.

The feedb-ox 1 is sealed to vat 2, and a Eourdrinier screen 3 is trained in the vat 2 over guide and drive rolls of which only two

rolls

4 and 5 are seen in the drawing. The screen 3 travels from the roll 4 to the roll 5 in an obliquely upward path parallel to the major screen faces and constitutes a foraminous partition between the box 1 and vat 2. The screen travels in conforming engagement over the open orifices of four superimposed suction chests 6 which are connected to a vacuum pump through control valves in a manner not further illustrated.

An inlet 7 extends over the width of the feed box bottom in a portion of the box 1 which is remote from the screen 3. Liquid 8 supplied through the inlet 7 and otherwise, as will presently become apparent, is maintained at a constant level in the feedbox 1 by an overflow 9. Liquid is also supplied to the feedbox 1 through a horizontal cylindrical feed pipe 10 which passes through a stuffing box 11 in the vertical wall of the box opposite the screen 3, and is adjustable toward and away from the screen.

The free end of the pipe 10 in the feedb'ox carries a nozzle 12. The attached nozzle end 12a is a tube of approximately square cross section. The nozzle flares horizontally and tapers vertically toward its discharge orifice 13 which is closely adjacent the screen 3, and whose walls are inclined in such a manner as to define with the screen a gap of uniform width, as best seen in FIG. 1. The flow section of the nozzle increases substantially uniformly from the square tube 12a almost to the orifice 13, and the width of the nozzle increases abruptly immediately adjacent the orifice.

A duct 14 is slidably sealed into the top wall of the square tube 12a and carries a small open tank 15- provided with an overflow 15a. The duct slopes obliquely from the tank 15 to the tube 12:: in a direction which is downward and forward with respect to the direction of liquid flow through the nozzle 12.

A pulley 16 arranged above the tank 15 guides a tow 17 of continuous filaments into the duct 14 and into the feed portion 12a of the nozzle 12. The pulley and tow have been omitted from the showing of FIG. 2 for the sake of clarity. The fibrous material emerges from the apparatus on the screen 3 as a continuous fiber web or fleece 18 not shown in FIG. 2.

In the operation of the apparatus, water or an aqueous suspension of individual relatively short fibers is supplied to the fee-dbox 1 through the inlet 7, and constitutes a first portion of the liquid 8 in the box. The liquid is drawn through the screen 3, and is discharged from the vat 2 through the suction chests 6. Any fibers suspended in the liquid 8 are deposited on the screen 3. If the amount of suspended fibers were suificient, a continuous web would be formed therefrom on the screen 3 in a manner known in itself.

Water is also supplied through the horizontal feed pipe 10 at such a rate that the water velocity in the square tube 12a is much greater than the traveling speed of the screen 3 and greater than the rate of movement of the liquid 8 through the screen. The static head in the tube 12a is sufficient to raise the water level in the tank 15 to the overflow 15a, which is higher than the overflow 9.

The rapidly moving stream of water in the tube 12a draws the tow 1-7 from the pulley 16 into the nozzle 12. Because of friction at the pulley 1 6 and elsewhere in the filament supply, not further illustrated, the filaments travel through the square tube 12a at a speed somewhat slower than that of the aqueous carrier, but the feed rate of the latter is-selected so that the travel speed of the tow is still greater than that of the screen 3, and preferably between 1.1 and times the screen speed.

The tow originally consists of continuous monofilaments which are practically parallel to each other and to the direction of tow movement. As the tow enters the horizontally diverging portion of the nozzle 12, the velocity of water flow decreases, and the linear velocity of the filaments also decreases while they are spread laterally over the width of the nozzle. The filaments are thereby arcuately bent and the several filaments are interengaged when they pass through the orifice 13 into the slowmoving liquid 8, and are transferred to the supporting face of the screen 3 by the flowing liquid.

If only water is supplied through the inlet 7, a selfsupporting we b consisting of .interengaged continuous filaments is continuously formed on the screen 3 from the layer'of interengaged filaments. It is separated from its water content by suction boxes, not illustrated, and is finished in a manner conventional in paper manufacture. If fibers of conventional finite length are suspended in the water supplied through the inlet 7 in a conventional materials, synthetic fibers or natural fibers.

manner, the shorter fibers are admixed to and interen- I gaged with the continuous filaments .on the screen 3.

Whether produced from continuous filaments alone or from mixtures of continuous filaments with fibers of conventional length, the paper-like sheet materials produced according to the method of the invention are free from cloudiness and have high strength. The absence of cloudiness is believed due to the fact that the loadbearing fibers do not have free ends. The extent to which they may be tangled by turbulence in the carrier liquid is thereby limited. Carrier tunbulence is believed to be at the root of the cloudiness observed in sheet made from relatively long or thin staple fibers.

If shorter fibers are admixed to the continuous filaments, they are interengaged with the filaments in a homogeneous pattern. Stresses applied to the finished sheet do not tend to separate the continuous filaments from the shorter fibers, and the amount of bonding agent necessary to provide desired properties to the sheet need not be greater than is needed for imparting the required cohesion to a corresponding sheet consisting either of continuous filaments alone or of shorter fibers alone.

Because the linear velocity of the filaments entering the nozzle 12 is-hi-g'her than that of the filaments reaching the screen 3, the consecutive longitudinal portions of each filament are superposed on the screen face in a position which is randomly oriented relative to the direction of movement, and the several filaments interengage with each other and with the shorter fibers deposited from the liquid 8 in a three-dimensional pattern.

Many continuous filaments presently employed in the textile industry have been found to be suitable for the method of our invention. Filaments mainly consisting of synthetic resins, and particularly of thermoplastic resins, are partiou'lanly useful, whether they be employed with or without staple fibers of the same or of other Polyester filaments, filaments of polyacrylonitrile and other acrylic polymers, polyamide and polypropylene filaments are representative of the range of thermoplastic synthetic resin filaments that may be used. The invention, however, is not limited to specific materials. Continuous glass and asbestor filaments, and filaments of modified natural materials, such as regenerated cellulose or rayon have been found entirely satisfactory, and impart to the paperl-ikc-sheet material such properties as capability of thermal bonding, heat resistance, chemical resistance, and the like, as will be apparent from the nature of the materials employed. 7

Instead of collecting a multiplicity of filaments in a tow, we have successfully performed the method of the invention by extruding a fiber forming material through a spinning nozzle having multiple orifices into a spinning or precipitating bath, and by feeding the bath with the precipitated filaments directly to the nozzle 12 through the pipe 10.

It will be appreciated that additional nozzles 12 with associated feed pipes 10 may be arranged in the feedbox 1 in such a manner that their orifices 13 are juxtaposed in the direction of movement of the screen 3, whereby a web of several interengaged layers may be for-med in a manner more fully described in the afore-mentioned copending application. The ratio between the sheet strength in the direction of screen travel and transversely thereto depends on the ratio between the traveling speed of the screen and the speed at which the tow 17 enters the nozzle 12. A uniformity of longitudinal and transverse strength not readily achieved in any other manner can be obtained in a sheet produced on a machine of the invention having at least two nozzles by feeding the filaments to the two nozzles at different speeds, each greater than the screen velocity.

Filaments which are straight, not twisted or doubled, are preferred for use in the illustrated paper making machine because they respond most readily to the changing direction and velocity of carrier flow. The introduction of airinto the carrier is to be avoided as far as possible, and this also is'more readily accomplished with straight individual filaments than with those which are twisted or doubled about each other.

The tow 17 enters the nozzle 12 through a body of water in the tank 15 which is stationary, or moves only at a very low rate adjustable by setting the height of the overflow 15a as the duct 14 is move-d inward or outward of the square tube 12a. It will be understood that means, not illustrated, are provided for securing the duct in the selected position. The tow, therefore, does not draw a significant amount of air into the nozzle, and the location of the orifice 13 below the level of the overflow 9 further prevents introduction of air into the web as it forms on the screen 3.

The substantially flat walls of the tube 12a and of the horizontally flaring portion of the nozzle produce very little turbulence in the flowing liquid carrier. The individual filaments are therefore readily separated from each other and spread over the width of the orifice 13. Bafiles arranged in the pipe 10 and parallel to the pipe axis may be provided to enhance linear liquid flow and to minimize major turbulence in the nozzle 12, but are not usually needed. More uniform distribution of the filaments over the width of the orifice 13 is obtained under some specific conditions if the vertical width of the slotshaped orifice is slightly greater at its center than at its ends. Adjustment for specific flow conditions may also be made by rotating the duct 14 about its axis and by axially shifting the duct.

If so desired, the inlet 7 may be blocked, and all liquid may be supplied through the feed pipe 10. It is usually preferred not to feed short fibers through the .pipe 10.

The following example is further illustrative of the present invention, and it will be understood that the invention is not limited thereto.

Example Ten strands of filaments were fed to the apparatus illustrated. Each strand consisted of about 2500 viscous rayon filaments of 1.6 denier each. The filaments were initially practically straight and parallel to each other. A mixture of short rayon staple fibers with low-melting thermoplastic Polypropylen fibers was suspended in the water fed to the inlet 7 at such a rate that the web deposited on the screen contained 40 percent continuous filaments, 40 percent staple rayon fibers, and 20 percent thermoplastic binder fibers.

The velocity of the water stream in the square tube 12a was 60 meters per minute, the rate of movement of the filament tow 17 was 40 meters per minute, and the traveling speed of the screen 3 was 30 meters per minute.

The web had practically uniform thickness and composition over its width of 120 centimeters. It was dewatered on the screen in a conventional manner and was ultimately passed over a calender roll heated to a temperature sufiicient to fuse the thermoplastic material.

A paper-like sheet material having high strength and suitable for application as a non-woven material :for clothing and industrial purposes was obtained.

If the stufiing box 11 has an internal spherical surface, and the pipe 10' is equipped with a corresponding spherical sleeve engaging the spherical stufling box surface, the nozzle 12 is not only capable of movement toward and away from the screen 3, but may also be moved parallel to the screen face, for example, by a motor driven crank and a connecting rod hingedly attached to the crank and to a portion of the pipe 10 outside the box 1. Reciprocating movement of the orifice 13 transversely of the direction of screen movement further contributes to the interengagement of the several continuous filaments.

If a paper-making machine of the invention is equipped with several nozzles 12 whose orifices are offset in the direction of screen movement, each nozzle is preferably provided with its own crank drive so as to permit different lateral reciprocating movement of the filaments which are deposited in successive strata of the web formed on the screen 3. Closely analogous results, however, may also be obtained by merely varying the rate of travel of corresponding tows of filaments.

Shifting the duct 14 in the tube of the illustrated apparatus changes the rate at which the filaments are being entrained by the uniform stream of water from the feed pipe 10, and corresponding adjustments in two nozzle arrangements of the type shown in the drawing permit filaments to be discharged from the associated nozzle orifices at very different rates, thereby varying the relationship between filament portions extending longitudinally and transversely of the direction of screen movement. Reciprocating movement of the nozzles and adjustment of tow speed, of course, may be combined in any desired manner.

Several vertically superimposed nozzles may be separated from each other by one or more horizontal partition walls in the manner disclosed in the afore-mentioned copending application. When two horizontal, vertically spaced partition walls are interposed between two nozzles, there may be produced a continuous web having two outer layers mainly or exclusively consisting of continuous filaments, and a central layer made of fibers of finite length in a manner evident from the copending application.

In view of the wide variety of filamentous materials that may be converted by the method of this invention into continuous webs consisting mainly or exclusively of continuous filaments, the afore-mentioned modifications and adjustments of the illustrated apparatus are merely intended to be illustrative. Specific optimum operating conditions cannot readily be calculated in advance, and some experimentation is unavoidable. Unless but a single product is to be produced from a uniform feed material, it is important that the spacing between the orifice 13 and the moving screen 3 be adjustable, and that the duct 14 may be shifted to vary to location of its orifice in the tube 12a.

While the invention has been describe-d with particular reference to specific embodiments, it is to be understood that it is not limited thereto, but is to be construed broadly and restricted solely by the scope of the appended claims.

What we claim is:

1. A method of forming an elongated, longitudinally continuous web which comprises:

(a) moving a foraminous support having a face in a direction of movement substantially parallel to said face at a predetermined speed;

(b) causing a liquid carrier to How continuously in a predetermined direction of flow transverse of said direction of movement from a feed area remote from said carrier to a deposition area adjacent said support, the velocity of flow of said carrier in said feed area being substantially greater than said predetermined speed and decreasing from said feed area toward said deposition area;

(c) continuously feeding a multiplicity of continuous filaments to said carrier in said feed area at a feeding speed substantially greater than said predetermined speed, but smaller than said velocity of fiow in said feed area, whereby said filaments are elongated in the direction of flow in said feed area and are interengaged with each other in said deposition area; and

(d) depositing the interengaged filaments on said face of the support (1) the interengaged filaments being sufiicient in number to form a self-supporting web on said face.

2. A method as set forth in claim 1, wherein said carrier is separated from said filaments after the same.

are deposited on the support.

3. A method as set forth in claim 1, wherein said velocity of flow in said deposition area is greater than said predetermined speed.

4. A method as set forth in claim 1, wherein said feeding speed is between 1.1 and times said predetermined speed.

5. A method as set forth in claim 1, wherein said filaments constitute initially an elongated strand of substantially parallel filaments suspended in said carrier, said strand and the flowing carrier being spread in a plane transverse of the direction of movement thereof and the speed thereof being reduced during said spreading, whereby the spread portions of the filaments are interengaged with each other so as to form a layer of filaments substantially extending in said plane, said layer being superposed on said face.

6. A method as set forth in claim 5, wherein fibers of finite length are admixed to said layer after said interengaging.

7. A method as set forth in claim 1, wherein fibers of finite length are admixed to the interengaged filaments.

8. An apparatus for forming an elongated longitudinally continuous web comprising, in combination:

(a) a container;

(b) an endless foraminous support having two opposite major faces, a portion of said support constituting a movable Wall of said container, whereby one of said faces is partly in the container;

(c) means for moving said support at a predetermined speed in an endless path, a portion of said path contiguously adjacent said container being parallel to said wall;

(d) an inlet for admitting liquid to said container;

(e) suction means for withdrawing liquid from the other face of said support in said portion of said path;

(f) means for defining a liquid level in' said container, at least a portion of said one face being below said level in said container;

(g) a conduit having an orifice adjacent said portion of said face and a feed portion spaced from said orifice, said conduit flaring from said feed portion to said orifice, said orifice being below said level;

(h) means for admitting a liquid to said feed portion for movement in the conduit toward said orifice at a speed substantially greater than said predetermined speed; and

(i) means for admitting a multiplicity of filaments to said feed portion for engagement by the admitted liquid.

9. An apparatus as set forth in claim 8, wherein said orifice is elongated in a direction substantially parallel to said portion of said one face, and transversely of the direction of movement of the same.

10. An apparatus as set forth in claim 8, further comprising means for moving said orifice toward and away from said one major face in said portion of said path.

References Cited by the Examiner UNITED STATES PATENTS 2,731,066 1/ 1956 Hogendobler 16l72 2,875,503 3/1959 Frickert et a1 161--72 2,913,365 11/1959 Osborne et al. 162320 FOREIGN PATENTS 568,790 l/1959 Canada.

DONALL H. SYLVESTER, Primary Examiner.

J. H. NEWSOME, Assistant Examiner.

Claims

1. A METHOD OF FORMING AN ELONGATED, LONGITUDINALLY CONTINOUS WEB WHICH COMPRISES: (A) MOVING A FORAMINOUS SUPPORT HAVING A FACE IN A DIRECTION OF MOVEMENT SUBSTANTIALLY PARALLEL TO SAID FACE AT A PREDETERMINED SPEED; (B) CAUSING A LIQUID CARRIER TO FLOW CONTINOUSLY IN A PREDETERMINED DIRECTION OF FLOW TRANSVERSE OF SAID DIRECTION OF MOVEMENT FROM A FEED AREA REMOTE FROM SAID CARRIER TO A DEPOSITION AREA ADJACENT SAID SUPPORT, THE VELOCITY OF FLOW OF SAID CARRIER IN SAID FEED AREA BEING SUBSTANTIALLY GREATER THAN SAID PREDETERMINED SPEED AND DECREASING FROM SAID FEED AREA TOWARD SAID DEPOSITION AREA; (C) CONTINUOUSLY FEEDING A MULTIPLICITY OF CONTINUOUS FILAMENTS TO SAID CARRIER IN SAID FEED AREA AT A FEEDING SPEED SUBSTANTIALLY GREATER THAN SAID PREDETERMINED SPEED, BUT SMALLER THAN SAID VELOCITY OF FLOW IN SAID FEED AREA, WHEREBY SAID FILAMENTS ARE ELONGATED IN THE DIRECTION OF FLOW IN SAID FEED AREA AND ARE INTERENGAGED WITH EACH OTHER IN SAID DEPOSITION AREA; AND (D) DEPOSITING THE INTERENGAGED FILAMENTS ON SAID FACE OF THE SUPPORT (1) THE INTERENGAGED FILAMENTS BEING SUFFICIENT IN NUMBER TO FORM A SELF-SUPPORTING WEB ON SAID FACE.

8. AN APPARATUS FOR FORMING AN ELONGATED LONGITUDINALLY CONTINUOUS WEB COMPRISING, IN COMBINATION: (A) A CONTAINER; (B) AN ENDLESS FORAMINOUS SUPPORT HAVING TWO OPPOSITE MAJOR FACES, A PORTION OF SAID SUPPORT CONSTITUTING A MOVABLE WALL OF SAID CONTAINER, WHEREBY ONE OF SAID FACES IS PARTLY IN THE CONTAINER; (C) MEANS FOR MOVING SAID SUPPORT AT A PREDETERMINED SPEED IN AN ENDLESS PATH, A PORTION OF SAID PATH CONTIGUOUSLY ADJACENT SAID CONTAINER BEING PARALLEL TO SAID WALL; (D) AN INLET FOR ADMITTING LIQUID TO SAID CONTAINER; (E) SUCTION MEANS FOR WITHDRAWING LIQUID FROM THE OTHER FACE OF SAID SUPPORT IN SAID PORTION OF SAID PATH; (F) MEANS FOR DEFINING A LIQUID LEVEL IN SAID CONTAINER, AT LEAST A PORTION OF SAID ONE FACE BEING BELOW SAID LEVEL IN SAID CONTAINER; (G) A CONDUIT HAVING AN ORIFICE ADJACENT SAID PORTION OF SAID FACE AND A FEED PORTION SPACED FROM SAID ORIFICE, SAID CONDUIT FLARING FROM SAID FEED PORTION TO SAID ORIFICE, SAID ORIFICE BEING BELOW SAID LEVEL; (H) MEANS FOR ADMITTING A LIQUID TO SAID FEED PORTION FOR MOVEMENT IN THE CONDUIT TOWARD SAID ORIFICE AT A SPEED SUBSTANTIALLY GREATER THAN SAID PREDETERMINED SPEED; AND (F) MEANS FOR ADMITTING A MULTIPLICITY OF FILAMENTS TO SAID FEED PORTION OF ENGAGEMENT BY THE ADMITTED LIQUID.