DE2000075A1 - Process for forming a continuous tubular article - Google Patents

Description

Dr. Dioi-r F. M ο rf
Dr. Hans-A. Browns

Munich 36, Piinzen «ueritr.iS

Jan 2, 1970 582-565

PHILIP MORRIS INC.
100 Park Avenue, New York 10017, V.St.A.

Method of forming a continuous tubular article

The invention relates to the shaping of a filled tubular object, for example a cigarette filter rod, in a continuous operation. In the manufacture of cigarettes, it is common practice to form the filter rod in a continuous operation characterized in that a continuous Fäserkabel of a filter medium, usually cellulose acetate, wrapped in a continuous paper wrapper that can be referred to as "nozzle case ¹¹ (plug wrap) However, this known method for producing a cigarette filter rod has disadvantages which make it impossible for use in modern cigarette production technology, in which very high production speeds are desirable.

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make suitable. For example, the use of an adhesive bond or seam limits the speed of the Production line to a value no higher than about 90 meters (about 300 feet) per minute.

A filter rod, in which the aforementioned problem is overcome, is in the United States patent application 747,279 from 2H. Described July 1968. The mouthpiece described in the cited patent application is produced by that plastic is extruded over a fiber cable. The advantages of making a strand of mouthpiece on top of this There are many ways, especially with regard to the precise regulation of the strand format and the improved uniformity of product manufacturing. Certain uses of that described in the aforementioned US patent application However, filter rod make it desirable that an improved attachment of the cable within the Plastic sleeve is obtained so that it has a higher gas flow pressure than would normally occur when smoking one Cigarette occurs, can withstand.

The present invention is directed to a method by which a thermoplastic tubular article, which is filled with a gas- or liquid-permeable filling material »for example a cable-filled one Cigarette sticks, continuous length through a continuous molding process can be produced, the production of the article by measures is drawn, which enable the formation of longitudinal grooves on the inner wall surface of the strand, which are used to hold or anchor the cable to the plastic in which it is enclosed. The object itself is new in itself and suitable for use for purposes other than merely as a filter device in a smoker's article, especially for purposes in which a flow medium of relatively high pressure through a

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Filter device passes. The invention is further characterized by a constancy of the treatment in the finished product and by the density of the filter medium, the is enclosed within the tubular plastic workpiece,

According to the invention, the filter rod is produced in that a tubular thermoplastic workpiece, preferably of circular cross-section, is continuously extruded from an extruder nozzle, the extrudate leaving the nozzle with a diameter which is slightly larger than that of the hardened finished workpiece, but with an external shape, which is substantially matched to that of the finished product, and with a smooth inner wall surface, at the same time a partially compressed tow of fibers or filaments of filter material is advanced axially into the plastic extrudate and with a movement in the same direction as this as the extrudate exits the forming die. The fiber or thread cable only comes into contact with the extrudate when the latter has moved forward by a certain amount downstream of the outlet opening of the nozzle from which it emerges, whereby the first contact occurs when the extrudate against the Cable is pulled down to form a sleeve which covers the latter, and when the two pass through the inlet seal of a cooling chamber, in which the latter the heat is dissipated from the plastic extrudate, and this is calibrated, so that.1 its outer dimension and Form can be precisely regulated within prescribed limits. To form grooves extending in the longitudinal direction with intermediate webs on the inner wall surface of the workpiece, flows of a cooling medium are injected or sprayed against the mentioned inner surface at the location of the webs. The surfaces forming the webs are therefore immediately adequately cooled or

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frightens to initiate their solidification. Then, when the workpiece changes from an initial to a smaller one The end format is pulled down, the sleeve is pulled down or stretched to a lesser extent on the faces, which are sprayed with dome cooling medium than on the surfaces lying between the sprayed surfaces. By the stronger pulling down or stretching of the sleeve on the not sprayed surfaces results in circular spaced grooves on the inner wall surface of the sleeve, in which the cable filler anchored. The type of anchoring of the cable within the sleeve is such that a blowout the cable is prevented when a gas or liquid flow with pressures passes through the object, which are significantly higher than those normally encountered when testing and smoking cigarettes, which means the object is made more suitable for the purposes mentioned, but also for other purposes where filters be used for media other than smoke. The facility and process by which the cooling of the Extrudate is made to its outer surface in dar To solidify the manner described above are the same as in the US patent application 7U7.37O dated July 24, 1968 described.

According to the invention and furthermore as described in the first-mentioned US patent application, different types of material can be used as filler material and different types of thermoplastic can be used for the tubular workpiece from which the filler material is coated. In most cases, however, cellulose acetate is used as the filter medium. To confer with the aim of the filler has a uniform density and a cohesive Gesantcharakter, it is customary, as also happens in the known filter rod manufacturing process, the fibers or filaments thereof to be treated with a plasticizer, thereby binding the fibers to each other of different that

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Favor cord-forming threads.

For a better understanding of the invention, it is described below, for example, in connection with the enclosed The drawing is described in more detail and shows:

Fig. 1 is a view in vertical section of the device, with which the cable-filled strand according to the invention is formed j

Fig. 2 is a view of the tubular workpiece in Leaving the outlet opening ″ of the one shown in FIG. 1 Extruder in cross section along the line H-II in Fig. 1;

3 is a perspective view of a representative length of the product made in the manner of the present invention cable-filled filter rod;

Fig. 4 is an end view of the strand length shown in Fig. 3; from which the manner in which the cable is inserted in the grooves of the tubular Plastic workpiece is held.

In the following description, the same reference numerals are used same parts in the drawing.

The invention relates to a method for molding filled plastic tubes in a continuous operation, for example a continuous hollow tube whose Bore is filled with a fiber material cable, directed. In particular, the invention is for an improvement of the method and subject matter described in the first-mentioned US patent application. Of the

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The subject of the invention is as a device for filtering gaseous or liquid media, including cigarette smoke, usable, however, because of the manner in which the cable is retained in the grooves of the plastic sleeve the article is particularly suitable for use as a gas or liquid filter in which a high flow pressure occurs. The mass according to the invention is also suitable Item also for use as a dye cartridge, as an antiseptic throwaway swab for hospitals and for similar inexpensive checkout manufactured fiber-filled devices.

To describe an exemplary embodiment of the Invention reference is made to Fig. 3, from which it can be seen that the filter rod 10 by a thin-walled plastic sleeve 12 is formed of substantially circular cross-section, the a filler material 14, for example a Enclosing a fiber or thread cable made of cellulose acetate, the cable serving as a filter medium.

The overall diameter of the sleeve 12 illustrated, which is intended for insertion into a cigarette is approximately 7.6 mm (0.3 ") / all thickness in the range between 0 ^ 3 to 0.38 to 0.50 mm at a V (0.005 "to 0.015" to 0.020 "), although changes in these dimensions may of course be made depending on the intended use of the article. For example, the strand shown in FIG. 3 can be used as the mouthpiece portion for the ventilated cigarette described in U.S. Patent Application 632,336 of April 20, 1967. As can be seen, the sleeve 12 is provided on its inner wall surface with alternating grooves 5 and webs 6 such that the latter are located between the grooves and these serve to receive the filler material 14 and as anchors or retaining means to make the filler material more firmly within the sleeve to

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to back up. By using a larger dimension for the anchoring of the film material, the filter rod can be a considerable liquid or gas pressure flow withstand it through.

The strand shown in Fig. 3 expediently has one outer dimension within the prescribed limits and when used as a filter mouthpiece for a ventilated cigarette, the circumference of a circle should be the circumscribes the tips of the fillets 16, preferably 23.9 mm - 0.05 now. The reasons for the adjustment this circumferential dimension with such accuracy are ^ described in more detail in the aforementioned US patent application 747,370 of July 24, 1968, but happens it mainly to bring the conditions down to a minimum, causing a malfunction in the cigarette machine can cause when the filter mouthpieces are combined with the tobacco cylinders.

1 shows a device, generally designated 20, with which a cigarette filter rod 10 according to the invention can be produced. The apparatus 20 is generally similar to that described in the latter U.S. patent application, but has been modified from the same in the extruder die design, the details of which are given below. Prior to forming the cigarette filter web 10 the filter medium, which in the illustrated embodiment is formed by a cable made of cellulose acetate fibers, is passed through a coating card (not shown) in which the fibers or fibers are coated with a plasticizer which, for example, from a solution of 3 % to 12% (but preferably 9%) consists of triacetin The plasticizer is used to bind the fibers to one another in the cable at the crossover or contact points of the fibers

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favor and thereby a cohesion in the mass of the Bring about cables. The cable is advanced by a suitable conveyor to all tensions except A low tension of about 20-5Og tension in the cable feed in the longitudinal direction to be canceled, as it is preferable is that the cable is treated with as little tension as possible. The cable is then partially compressed and in a manner known per se to a continuous cylindrical body immediately before the feed the same shaped to the cross-head drawing form. The cable entering the drawing mold has a larger diameter than the intended final inside dimension of the sleeve 12, however, and for the reasons set forth below Has diameter which is smaller than the inner diameter of the extrudate leaving the die. The extrusion tool, which is of the transverse head type, has a body part 28 in which a mandrel 30 is mounted in a manner known per se which is located from the inner bore of the body part 28 at a distance, so that it is an annular space in the body part limited, is absorbed by the molten plastic 32, which in the cross-head drawing form laterally enters a container, not shown. Depending on the speed at which the extruder screw (not shown), which promotes the molten plastic 32, itself rotates, a continuous tubular material of heated plastic emerges from the mouth or extrusion orifice the cross-head drawing die at 34 and is moved away from this by peeling rollers 64 downstream of the device conveyed, the extrudate as it emerges from the extrusion opening Has cross-sectional dimensions that are significantly larger than the intended final cross-sectional dimensions of the finished filter rod, and wherein the extrudate is heated sufficiently to be plastically deformed, and the inner surface at 35 is sticky or in a plastic state. The extrudate also has a Exterior surface design that essentially corresponds to that

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of the finished product corresponds to the purpose for which the cross-head drawing mold 22 can be equipped with a suitable shaping device in order to communicate the required external design to the extrudate. For example, an intermediate or fitting piece 21 can be detachably attached to the housing 28, which intermediate piece has an extrusion opening with which the special inner and outer surface design of the extrudate can be achieved. Simultaneously with the exit of the tubular workpiece 12 from the drawing die, the compressed cable 14 of filter medium passes through a central cylindrical channel formed in the mandrel at 38. The cable moves axially and in the same direction as the extrudate when it leaves the drawing die 22 forwards, the cable mass at this point having a diameter which is at least slightly larger than the inner diameter of the sleeve when the latter is fully treated is. As can be seen, the rectified movement of the extrudate 12 and the cable IU downstream of the exit point from the cross-head drawing die 22 over a short distance is a movement in which the hot extrudate does not touch the cable. This is provided so that the extrudate can be pulled down in its caliber in the above-mentioned movement path in such a way that the extrudate does not first come into contact with the cable until the composite structure has passed through the closable opening of the inlet seal 42 of the cooling device

chamber 40 passes through. As the heated extrudate is drawn down, its overall cross-sectional dimensions can be reduced by up to 100% from the initial extruded dimensions to the smaller final strand dimensions. For example, in the strand 10 for use as a cigarette ingredient, the sleeve 12 generally has a wall thickness of 1.27 mm (0.050 ") when extruded, while being substantially in the range of 0.12-0.0 when drawn down on its thicker portions .38 mm CO. 005 "to 0.15») haf.

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When extruding the tubular workpiece or the Sleeve 12 allows the invention to extend in the longitudinal direction extending grooves 6 on the inside thereof as part of the extrusion process in a relatively simple, however, in a highly effective manner. The mandrel 30 is provided with a circular arrangement of channels 110, which extend through this from one end to the other and at one end with a collecting caral 112 are connected, which is formed in a plate 114 and at their other ends open into channels 121 adjacent to the opening, from which the workpiece 12 exits, which outlet is provided on the inside of the workpiece. The collecting channel 112 is through a line 116 connected to a source 118 for compressed air or other pressure medium. This other leverage should of course be compatible with the overall shaping process. For example, the plasticizer with which the cable is coated may be used for cooling, although it should be noted that gaseous refrigerants are preferred. As shown, When the heated extrudate 12 exits the extrusion orifice, cooling air flows against the smooth inner surface of the same directed at a circle of places, As shown in FIG. 2, which points correspond to the positions of the webs 6, the currents preferably in emerge in a direction parallel to the extrusion axis. The effect of the cooling air jets on the mentioned surfaces strike is to deter them and some Initiate consolidation or hardening of these surfaces. The degree of solidification introduced is such that when the workpiece is then pulled down as it moves to and through the closable opening moved forward, the sleeve is pulled down differently, i.e. to a lesser extent in the longitudinal direction along the surfaces forming the webs 6 than on the surfaces lying between the webs. Therefore the sleeve is

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proportionally drawn down along the adjacent longitudinal strips which form the webs and grooves, the stronger pulling down on the intermediate surfaces forming the grooves 5 takes place. The total pulling down of the inner wall surfaces which form the grooves are shown in dashed lines in FIG. When the sleeve is in its caliber is pulled down, the cable is held on the surface of its mass in the liuten 5, whereby an anchoring of the mass is obtained. Ausserden learns the cable is glued to the sticky surfaces in the hats » thereby securing the mass within the sleeve. Since the grooves have an increased. Result in area, (lbcr which this gluing can take place, learns overall cable anchorage an improvement. The cable also adheres to the surfaces of the webs 6, as these, though the hardening of these surfaces has been initiated by spraying with the coolant, these have sufficient tack retained in order to effect this additional bonding.

The assembled object is cooled at its entry into the cooling chamber UO through the inlet seal U2, the plastic sleeve being sufficient and equal massively tight against the cable ur.d to about the optimal Final dimension that you get. Should have entry into the seal, is pulled down. Leg pulling down the sleeve the cable mass of the filling material IU is another and subjected to final radial compression. As already mentioned, the inlet seal serves as a closable one opening that is essentially the same diameter and shape as the outer end diameter of the sleeve Has. Therefore, in the finished object, the sleeve 12 encloses the cable mass with an inevitable narrowing of the the latter, so that the cable completely fills the anchorages formed by the grooves 5.

As it passes through the cooling chamber, the combined

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Set object is passed through submerged in the cooling water bath 4 6 and passes through a series of calibration plates provided with an opening in the method described in the US patent application 474.370 of July 24, 1968 for exact accuracy
Adjustment of the circumferential dimension of the sleeve 12 through it. One of these plates is shown at 120. To calibrate the sleeve, which takes place in the same way as described in the aforementioned US patent application, the sleeve can be subjected to an internal pressure which tends to expand it radially in order to be tightly in calibration relationship with the
Hold calibration plates. The force to expand becomes
obtained in that the cooling chamber 40 and the medium 46
in this is kept under a vacuum state, while the space enclosed by the sleeve can be brought into connection with the outside air pressure, which can happen in addition to the presence of compressed air that is in the form of cooling currents to harden the inner surface of the
Workpiece, as described above, is initiated.

When leaving the cooling chamber 40, the object provided with a sleeve occurs between the wheels or rollers 64 of the Pulling devices through which convey the object through a cutting device (not shown) in which the Article of continuous length can be cut into short lengths as shown in Fig. 3, which can be used for further Processing, for example for use in a cigarette machine, are suitable.

The tubular article made in accordance with the present invention
can be used with advantage as the mouthpiece part of a ventilated cigarette. It is also suitable for use as a filter for other purposes, including hydraulic systems in which there is relatively high fluid pressure. A 10 mm long cigarette filter insert manufactured in the manner according to the invention

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The strand was both an underpressure of almost an absolute vacuum and an overpressure of 1.75 atmospheres (25 psig) with no appreciable pulling out of the cable from the sleeve. The filter cable is preferred formed by a large number of fibers or threads made of cellulose acetate, which extend in the longitudinal direction and with extend the same extent as the cable mass. Using with a polyethylene mouthpiece for a ventilated cigarette of the type described earlier, the cellulose acetate preferably a total denier of 25,000 to 7,5,000, but more preferably in the range of 30,000 to 50,000, which values on a fiber denier of about 1-16 gj |

and preferably 3-6 denier. Other materials are also suitable for use as a filler material include and can polyalkenes, polyethylene ^v and paper cable. The sleeve 12 can be molded from various types of thermoplastics including polyolefins, polypropylene, cellulose acetate and polyethylene and can have various external and internal dimensions and external surface configurations depending on the intended use.

From the foregoing it can be seen that the invention is particularly useful for shaping a fiber-filled thermoplastic strand is in which the filler material is anchored in the workpiece in longitudinally extending grooves which w

are formed in the workpiece. This is achieved according to the invention in a very effective way that the cooling air flows from ambient temperature against the inner surface of the tubular extrudate are directed as this leaves the annular extrusion orifice. The level of security of the filler material within the workpiece should be better with the strand produced in the manner according to the invention than be a strand formed by extruding thermoplastic material through an extrusion orifice wirdy has the tooth-shaped inner projections that. which to -

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corresponding to shaping grooves. It can be assumed that a stronger hold is achieved as a stronger The extrudate can be pulled down along the groove surfaces if the workpiece is pulled down along strips, which are located between already solidified surfaces. Another advantage of the invention is that it has the Production either of a plastic strand with a "toothed inner design, as shown in FIG. 4, or made possible by a strand with a smooth inner surface without the intermediate pieces being replaced on the drawing die Need to become. To produce a strand with a smooth inner surface, all that is required is the air supply switch off.

From the foregoing it can be seen that the objectives mentioned at the beginning as well as those that emerge from the preceding description can be effectively achieved and that certain changes may be made in the implementation of the foregoing The method and structure described can be carried out within the scope of the invention without, however, the Invention is limited to this. For example, the pressure at which the cooling air flows to the collecting duct 112 can be changed depending on the type of material to be extruded, as long as the pressure is not above a value that results in the workpiece 12 emerging from the drawing die breaking. Furthermore, the The range of the diameter of the channel 110 can be varied depending on the particular requirements. For example, the Channels for a sleeve 12 of the dimensions given above, the channels have a diameter of 0.4 mm to 0.8 mm (1/64 "to 1/32").

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Claims (9)

582-565 ^ January 2 ΊβΤο 1. Method of forming a continuous tubular - ' shaped object, in which the thermoplastic material through an annular extrusion opening to Forming a continuous tubular workpiece having a substantially smooth interior Has wall surface, but has cross-sectional dimensions that are significantly larger than the intended end cross-sectional dimensions Workpiece are then conveyed away from the extrusion opening and the tubular workpiece is essentially pulled down to the final cross-sectional dimensions in that it is closed by a lockable Opening of substantially the same dimension as the intended final outer dimension of the object is advanced characterized in that grooves are formed in the inner wall surface of the tubular workpiece extending in the longitudinal direction of the workpiece, with ridges between adjacent grooves thereby arise that currents of a cooling medium are sprayed against the inner wall surface of the workpiece at points which correspond to the position of the webs when the workpiece leaves the extrusion opening, thereby forming the aforementioned inner surface to cool sufficiently at the said points to initiate their solidification, the tubular Workpiece on its way to the closable opening and through this to a lesser extent to the mentioned places as drawn down on the surfaces uirci, which are located between the mentioned locations, creating grooves in the wall surface on the intermediate surfaces to be shaped » -15-00 9835/1705 _BAD 2. The method according to claim 1, characterized in that the cooling medium is air. 3. The method according to claim 2, characterized in that the air is at ambient temperature. U. The method according to claim 1, characterized in that the flows of the cooling medium are sprayed against the inner wall surface of the workpiece at points in the workpiece which are circularly spaced from one another and which
Currents are essentially directed downstream of the extrusion opening. 5. The method according to claim 4, characterized in that the streams are directed substantially parallel to the axis of the extrusion orifice. 6. The method according to claim 1, characterized in that at the same time a cable of a fiber filling material is moved forward into the tubular workpiece and in the same direction as it when it leaves the extrusion opening
will. 7. The method according to claim 6, characterized in that the thermoplastic material is polyethylene and that The fiber fill material is cellulose acetate. 8. Object, characterized by one for fluid _ ₁₆ "009835/1705 BATHROOM OBlGINAL 582-565 / f permeable mass O.4) made of a fiber material that passes through a plurality of fibers is formed which extend essentially in the longitudinal direction and with the same extent as the mass extend, with at least some of these fibers at other points of contact are held by adhesive and a tubular sleeve (12) made of a thermoplastic encloses the mass and at the same time compressing them radially, the inner surface of the sleeve is formed with grooves (5) extending into the longitudinal direction of the sheath and the fiber material for anchoring the mass (14) within the sleeve (12) picks up. 9. Article according to claim 8, characterized in that the fiber material adheres to the surfaces of the grooves (5). - 17 - 009835/1705 Blank page