US3110642A - Method of producing a fibrous product from extruded organic thermoplastic filaments - Google Patents

Description

1953 R. c: HARRINGTON, JR.. ETAL 3,1 METHOD OF PRODUCING A FIBROUS PRODUCT FROM EXTRUDED ORGANIC THERMOPLASTIC FILAMENTS Filed Sept. 9, 1960 Robert GHaningM James L. Smi th Jalnes H.130 nd INV EN TORS' cwmmm ATTORNEY}? United States Patent Jersey Filed Sept. 9, 1960, Ser. No. 545929 4 Claims. (Cl. 156.2)

This invention relates to a process for the manufacture of fibrous articles. More particularly, it relates to a process for converting fibro-pl-astic material directly into fibrous material suitable for smoking devices such as cigars and cigarettes, non-woven fabrics, cable stuillng, and the like.

The manufacture of fibrous material and products requires many complex steps. For example, paper for filters prepared in the conventional manner requires the steps of pulping, screening, drying and taking up on a roll. The paper is then crimped and split to the proper width and finally processed into filters. Cellulose ester filters are prepared by esterifying cellulose, dissolving in acetone, filtering the solution and spinning by the conventional dry spinning technique. Continuous filaments formed into tow in this manner or by a similar lengthy process from po-lyolefins or other fiber-forming substances are then orimped and baled. In making the filters, the tow is opened; that is, the filaments are spread apart. Then a bonding agent is *added, and the tow is passed into a garniture, a conventional cigarette-making machine. Sometimes various additives such as rice starch or carbon particles are used in paper and cellulose acetate filters to increase the surface area. The strong fibers required for use in non-woven articles, tows, webs, filters, and such formed from polymer solutions by prior art processes using various types of spray equipment have been collected in a number of difierent ways, for example, on a moving belt, on a preformed continuous rope or yarn, or a rotating card. In many cases, electrically charged plates have also bee-n necessary. As yet, no method has been devised whereby all of these complicated intervening steps can be completely eliminated so that wrapped or crimped fibrous products such as filters and the like can be produced directly from melts or solutions of the various polymers which can be used.

It is accordingly an object of this invention to provide a continuous process for the manufacture of filters from a polymer melt or solution.

It is another object of this invention to provide a process which is more economical and simpler than the multistep processes now employed in the manufacture of fibrous products.

It is also an object of this invention to provide a process for the manutfacture of filters from. more economical materials than those presently employed.

It is another object of this invention to provide a process whereby very fine filamentous material can be processed directly into filters and other fibrous products.

It is still another object to provide a process which will convert filaments with little resilience into a filter firm enough for use as a cigarette tip.

It is a further object of this invention to provide a simple, substantially one-step method of producing a continuous tow or web from a plastic polymer.

It is a still further object of this invention to provide a process for the collection of continuous tows of sprayed fibers of various diameters and lengths useful in filters, non-woven fabrics, cable stuffing, and the like and prepared directly from a molten polymer or polymer solution.

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These and other objects of this invention will be apparent from the description and claims which follow.

We have found surprisingly that a polymer melt or solution coming from a storage tank or other appropriate container can be directly converted into fibers which can then be either 1) continuously formed into tow and taken up continuously or which can be (2) collected and bound immediately in a garniture into a filter useful on a cigarette or cigar or other smoking device. This continuous operation is carried out by applying a stream of inert gas or steam propelled substantially at right angles to the melt or solution issuing from the supply container at a velocity and under a pressure suificient to attenuate the melt or solution into the fonm of fibers.

If it is desired to form the fibers directly into tow, the tow is collected in a direction substantially countercurrent to that of the propellant stream on a guide and take-up rolls. A belt or cord or other similar means for providing an initial collecting point for the fibers canbe used, but such an arrangement is not an essential part of this invention. A particularly suprising feature is the fact that substantially all of the freshly formed fibers find and adhere to the preformed tow. Although we do not know exactly why this happens, we theorize that such an arrangement of a propellant spray and countercu-rrent collection causes the formation of an air stream or blanket upon which the preformed tow rests. Once the tow starts to form, the take-up roll is started (the belt or cord or other similar means for providing an initial collecting point for the fibers, if used, being immediately removed from the system) and the tow continues to form in a continuous manner. It is collected in a suitable manner, for example, in a convenient receptacle or on one or more spools. The temperature of the propellant stream, its velocity and pressure should be adjusted so that the freshly formed fibers are still in the plastic state when they are formed into tow in order to adhere at the point of contact and produce a continuous filament.

The uses for tows and webs formed in accordance with' this procedures are many and varied. Cigarette filters, air and liquid filters and the like are illustrative of such. Tows formed from thermoplastic materials can be cut into uniform lengths on conventional textile processing equipment, blended with other fibers such as viscose and cotton, and formed into non-woven articles. Such tows and webs are also useful as packing or stufiing material and as decorative materials.

If, on the other hand, it is desired to convert the fibrous material directly into a final fibrous product, the arrangement can be altered so that the attenuated fibers formed by the propellant stream directed against the polymer melt or solution coming from the storage container and directed thereagainst at right angles are sprayed directly into a funnel, the narrow end of which connects with a specially arranged air aspirator. The fibers pass through the aspirator and on into a short multiperforate tube which extends into the horn of a garniture or other binding mechanism. The exhaust end of the aspirator terminates at a point close to the beginning of the short multiperforate tube. The exhaust air is dissipated through the multiperforate tube holes. Paper or other packaging material can be passed through a narrow slot between the exhaust end of the air aspirator and the rnultiperforate tube and thence through the tube along the lower side thereof into the garniture horn. This modification of the process is especially advantageous for the utlization of very short fibers, viz, less than about two inches.

It can thus be seen that by this particular procedure filaments can be prepareddirectly from the molten polymer or polymer solution and conveniently collected immediately thereafter in an appropriate wrapping or pressing device. The fibrous product can be a filter rod suitable for attaching to the tobacco portion of cigar, cigarette or other smoking device.

We have found that any plastic fiber-forming polymer, particularly the polyolefins and cellulose esters, are suitable for processing in accordance with this invention. Representative polyolefins which are especially appropriate are polyethylene and polypropylene. Cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate are illustrative of the cellulose esters.

Various modifications of the above-described process can be made, for example, where the fibers are formed directly into a very large tow, bat or wide web of fibers. A header can be used to supply the polymer melt to the propellant stream and a wide web formed in this manner. On the other hand, the propellant streams can be caused to converge to produce a more cylindrical tow. Several difierent polymers can be supplied from several sources to form a blended tow and the fiber size controlled by the techniques of varying the polymer-propellant fiow ratio. Various fluids such as air, steam, nitrogen or carbon dioxide, for example, can be used as the propellant with polymers such as the polyolefins, nylon, polyesters and cellulose esters such as cellulose acetate propionate. Actually, any fiber-forming material amenable to being sprayed can be used in this process. We prefer to use thermoplastic polymers such as polyolefins and cellulose esters with and without plasticizers for spraying.

The materials which can be sprayed to give the fine fibers for which this particular invention is especially adapted are quite varied. Although we prefer to use materials which can be sprayed from a melt, materials sprayed from a solution employing a volatile solvent can also be used.

When the fibers are formed directly into a fibrous prod net in accordance with the alternate procedure given above, the amount of compressed air used on the air aspirator and the garniture speed may be adjusted in accordance with the requirements of the type of fibers to be produced and the specific properties of the filter cigarettes or other smoking devices prepared.

The process of this invention may be more readily understood from the following description and drawings which illustrate certain preferred embodiments thereof.

FIG. 1 is a diagrammatic representation of an embodiment wherein a polymer melt or solution is converted directly into rod-like fibers by the application thereto at right angles of a propellant stream and the fibers formed into tow, which is collected on take-up rolls.

FIG. 2 is a diagrammatic representation of an alternative embodiment of this invention wherein the fibers are produced in accordance with the same procedure as that illustrated in FIG. 1 but are collected in a funnel-aspirator device and conveyed directly to a garniture wherein they are assembled as a final fibrous article.

Looking first at FIG. 1, a polymer melt issues from container into a propellant stream supplied from propellant nozzle 12. String-like fibers 14 formed by attenuation follow the propellant stream until they form into continuous tow 16 which is carried away by way of a plurality of guides 18, leading to take-up rolls 20 and 22 between which it passes. The tow is collected in a direction countercurrent to that of the propellant flow.

In the alternative embodiment shown in FIG. 2, the polymer melt from container 10 is formed into fibers 14 as in FIG. 1 by a propellant stream from propellant nozzle 12. The fibers now in string-shaped filament form are drawn through a funnel 24 by an aspirator 26 to which air or other appropriate inert gas or fluid is provided through line 28 and from which it is withdrawn through orifice 30. The filaments pass through multiperforate .tube 32, to which multiperforate tube 32 paper is supplied at point 36 from roll 34 into garniture horn 38 and thence into garniture 40, in which the final bound product is formed.

The following examples are illustrative of our invention, which is to be limited only by the appended claims.

Example 1 Fibrous tow was formed as in Example 1 with the ex ception that the molten polyethylene was at a temperature of C. and the size of the filaments was in the range of 3-10 denier per filament.

Example 3 Fibrous tow was formed as in Example 2 with the exception that a 15-pound air propellant stream was used and the filaments produced ranged in size from about 8-30 denier per filament.

Example 4 A stream of molten polyethylene such as that used in Example 1, except that the temperature thereof was 190 C. instead of 140 C. was introduced to a 50-pound steam propellant stream directed at right angles thereto, and the tow collected theretrom consisted of fibers having a size or from 0.5 to 5 denier per filament.

Example 5 Polyethylene having a density of 0.925 and an inherent viscosity at 300 F. of approximately 1000 centipoises was melted and introduced at 275 C. to a propellant stream of 50% steam directed at right angles thereto, and a tow consisting of fibers in the 3-20 denier per filament range was collected on take-up rolls such as those illustrated in FIG. 1.

Example 6 Fibrous tow was formed as in Example 1 except that polypropylene having a density of 0.91 and a viscosity at 320 C. of approximately 5,000 centipoises was used instead of the polyethylene.

Example 7 A stream of plasticized, molten cellulose acetate propionate /z-second propionate) was introduced to a 32- pound steam propellant stream in a manner illustrated by FIG. 1 to produce semi-continuous filaments in the range of about 100 denier per filament. The filaments were collected to form a continuous tow.

Example 8 Continuous tow was formed as in Example 7 with the exception that the plasticized molten cellulose acetate propionate was introduced to a 20-pound air stream at C.

Example 9 Continuous tow was formed as in Example 7 with the exception that cellulose acetate was used instead of cellulose acetate propionate.

Example 10 Continuous tow was formed as in Example 7 with the exception that cellulose acetate butyrate was used instead of cellulose acetate propionate.

Example 11 In this example numerical references are to FIG. 2 of the drawing. A low molecular weight polyethylene having a specific gravity of 0.907 and a viscosity at 300 F. of approximately 9,000 centipoises was melted in a blow case 10 with 75 pounds of steam in the case. A valve in the bottom of the case was opened and a stream of the molten material /s in diameter was caused to fiow from a short piece of tubing. A stream of compressed air ejected from a A tube 12 was directed at a right angle to the stream of molten material and in the direction of the funnel 24. Filaments varying from about /2 to 5 denier were blown into the funnel. An air dofler 26 stufled the filaments into a multiperforate tube 32 and on into a garniture 40 where they were wrapped with paper and converted into a tubular filter.

Example 12 A filter was prepared according to the procedure of Example 11 except that polypropylene having a specific gravity of .91 and a viscosity at 320 C. of approximately 5,000 centipoises was used instead of the polyethylene.

Example 13 A filter was formed in accordance with the procedure of Example 11 with the exception that cellulose acetate propionate was the polymer used.

Example 14 A filter was prepared as in Example 11 except that cellulose acetate was used instead of the polyethylene.

Example 15 The procedure of Example 11 was used to prepare a tubular filter, cellulose acetate butyrate being used in place of the polyethylene.

The following example is given to show the surprising and unobvious importance of drawing the filaments through the multiperforate tube before allowing them to enter the garniture horn when being formed directly into filters.

Example 16 The process of Example 11 was followed with the exception that the multiperforate tube was removed, the aspirator leading directly into the garniture horn. After a few minutes of operation, the filaments began to jam in the garniture in such a manner that no filters could be produced.

These examples serve to show only a few of the many variations possible in this process. Many changes can be made to give any desired tow consisting of any reasonable fiber size at either low or high rates of production. The examples show only sprayed fibers formed from polymer melts, but solvent solutions can also be use-d. When solvents are used, a solvent recovery system should be used.

It can readily be seen that We have provided a method whereby a molten polymer or a polymer solution may be directly converted by the impingement thereon at right angles of a propellant stream directly into fibrous tow or a fibrous product. To form a continuous tow, the fibers are withdrawn from a stream of fibers substantially countercurrent to the stream. This substantially countercurrent collection of tow is one of the features of this invention. When it is desired to form the filaments directly into a bound product such as a filter, they are drawn by means of an aspirator through a multiperforate tube which serves to allow excess compressed air to be dissipated evenly through the atmosphere and flius prevents clogging in the horn of the garniture into which they are conveyed for forming into the final product. Without the presence of the multiperforaite tube, a plug of fibers is formed which will pass on through the garniture and prevent the formation of the desired product.

We theorize that the reason for this is that the air is caused to turn and blow out of the mouth of the aspirator and thus prevent the increases in pressure necessary to force the fibers into the garniture.

Another feature of this invention is that the denier of the filaments formed by :our process is practically unlimited. As illustrated by the preceding examples, filaments varying all the way from /2 to 20 denier can be collected. A particular advantage is the capability of our The utility of the pnocess of this invention is manifold.

It can be used in forming fibrous material for twisting to make a cord or yarn, crimping and cutting into staple yarn, winding on frames for multi-shaped filters, or passing into the horn of a garniture in preparing filter rods.

Although the invention has been described in detail with reference to preferred embodiments thereof, it will be understood that variations and modification can be effected within the spirit and scope of the invention as described hereinabove and as defined by the appended claims.

We claim:

1. A process for producing a fibrous product from an organic thermoplastic substance which comprises extruding in a generally downward direction a molten flow of thermoplastic substance, attenuating said molten flow into a plurality of stringshaped fibers by directing a continuous stream of steam under pressure at approximately right angles to said molten flow, supporting said fibers only by said stream of steam, collecting said plurality of steam supported fibers in an elongated zone on a plane substantially horizontal with said stream of steam to form a tow of substantially parallel discontinuous filaments and withdrawing said tow at an angle to said zone and in a direction counter to the direction of said stream of steam.

2. A process for producing a fibrous product from an organic thermoplastic substance which comprises extruding in a generally downward direction a molten flow of said substance, directing a continuous stream of steam at an abrupt angle to said molten flow under suflicient pressure to propel said molten fiow and attenuate the flow into a plurality of string-shaped fibers, supporting the attenuated fibers only by said stream of steam, collecting said plurality of steam supported fibers in an elongated zone as a web of tow of substantially horizontally aligned discontinuous filaments and withdrawing said tow at an angle to said zone and in a direction counter to the direction of said stream of steam.

3. A process for producing a fibrous product from an organic thermoplastic substance selected from the group consisting of polyethylene and polypropylene which comprises extruding in a generally downward direction a molten flow of said substance, attenuating said molten flow into a plurality of string-shaped fibers by directing a continuous stream of fluid under pressure at approximately right angles to said molten flow, supporting said fibers only by said stream of fluid, collecting said plurality of fluid supported fibers in an elongated zone on a plane substantially horizontal with said stream of fluid as a tow of adhering substantially horizontally aligned filaments of 0.5 to 20 denier per filament and withdrawing said tow at an angle to said zone and in a direction counter to the direction of said stream of fluid.

4. A method for the treatment of organic thermoplastic material which comprises:

(1) directing a fluid stream substantially at a right angle to a downwardly moving flow of molten extruded organic thermoplastic material thereby attenuating said material into fibers moving in substantially the same direction as that of said fluid stream,

(2) collecting by air aspiration the attenuated fibers in substantially horizontally aligned adhering form while under the propelling influence of said fluid as a continuous web of tow made up of discontinuous filaments varying in denier from 0.5 to 20 and ILA) References Citefi in the file of this patent UNITED STATES PATENTS Tay1or Apr. 30, 1946 Manning June 12, 1956 8 Manning June 12, 1956 Crawford et a1. June 4, 1957 MacI-Ienry Nov. 12, 1957 Frickert et a1. May 15, 1959 Crawford et -al Aug. 25, 1959 Manning June 21, 1960 Miller July 19, 1960

Claims (1)

1. A PROCESS FOR PRODUCING A FIBROUS PRODUCT FROM AN ORGANIC THERMOPLASTIC SUBSTANCE WHICH COMPRISES EXTRUDING IN A GENERALLY DOWNWARD DIRECTION A MOLTEN FLOW OF THERMOPLASTIC SUBSTANCE, ATTENUATING SAID MOLTEN FLOW INTO A PLURALITY OF STRING-SHAPED FIBERS BY DIRECTING A CONTINUOUS STREAM OF STEAM UNDER PRESSURE AT APPROXIMATELY RIGHT ANGLES TO SAID MOLTEN FLOW, SUPPORTING SAID FIBERS ONLY BY SAID STREAM OF STEAM, COLLECTING SAID PLURALITY OF STEAM SUPPORTED FIBERS IN AN ELONGATED ZONE ON A PLANE SUBSTANTIALLY HORIZONTAL WITH SAID STREAM OF STEAM TO FORM A TOW OF SUBSTANTIALLY PARALLEL DISCONTINUOUS FILAMENTS AND WITHDRAWING SAID TOW AT AN ANGLE TO SAID ZONE AND IN A DIRECTION COUNTER TO THE DIRECTION OF SAID STREAM OF STEAM.

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