DK145591B - METHOD AND APPARATUS FOR MANUFACTURING TOBACCO SMOKE FILTERS - Google Patents

Description

(19) DENMARK (^ ¾)

i® (ice) PUBLICATION <n> 145591 B

DIRECTORATE OF THE PATENT AND TRADEMARKET SYSTEM

(21) Application No. 1086/72 (51) IntCI. * A 24 0 3/02 (22) Filing date 9 · Mar. 1972 (24) Race day 9 · tnar. 1972 (41) Aim. available 13 · s ep. 1972 (44) Presented Dec. 20; 1982 (86) International application # - (86) International filing day (85) Continuation day - (62) Master application no -

(30) Priority Mar 12 1971, 6693/71, GB

(71) Applicant BRITISH-AMERICAN TOBACCO COMPANY LIMITED, London, GB.

(72) Inventor John Anthony Luke, GB.

(74) Associate Engineer Hofman-Bang & Boutard.

(54) Method and apparatus for making two-stroke smoke filters.

The invention relates to a method of the kind set out in the preamble of claim 1.

A method of the kind disclosed is known from the disclosures of German Patent Specification No. 1,099,922 and U.S. Pat.

2 219 491. In both known methods, cylindrical filter parts operating with axial smoke passage are encased in smoke impermeable paper.

O From the specification to German Publication No. 1,532,246, an apparatus for filtering tobacco smoke is disclosed in which a flat strip of fiber material is enclosed by two semi-cylindrical plastic strips. The two semi-cylindrical portions are initially provided with collars which support the strips and force the two back smoke through a twisted path axially through the filter material.

German publication specification No. 1 936 429 discloses a method for producing an axially oriented filter in which a continuous strand of cellulose acetate fiber is fed within an extensible smoke-impermeable plastic strip, the strip being drawn to its final target after extruding none. compress the cellulose acetate fibers. Hereby, the plastic strip is directly extruded around the strand of the fibrous fibrous material. The combination of the outer grooved plastic strip on which the cigarette mouthpiece paper resides produces passage of such a nature that the outside air sucked through the passage is mixed with the smoke in the smoker's mouth.

German publication specification No. 2 018 558 discloses a cigarette filter in which a filter element is surrounded by a smoke-impermeable casing, and the filter element is designed to provide at least two substantially axially extending channels either through the filter element or between the filter element. and. along the inner surface of the sheath so that at each end of the channels there is provided a sealing device which, firstly, closes this end and, secondly, prevents smoke from passing through the end face or the end faces of the filter element.

French Patent Specification No. 1,580,776 discloses a process for producing a filter rod which is alternately made from portions of granular or fibrous material. The plugs are inserted at a distance into a vertical tube, and the granular material is inserted into the space between the axially tube-through plugs. The rod is enclosed by a plastic strip upon extrusion.

Finally, from German Publication No. 1,958,208, a method for producing a string of filter plugs with granular material, such as e.g. is encased in a plastic material. Each filter plug is then divided into two filter plugs by cutting the connector and after it is provided with an opening at each end inserted between two filter parts, e.g. with fibrous material. A plastic material is used to enclose the filter parts operating with axial smoke passage.

In contrast, the invention does not employ a tobacco smoke filter with axial tube passage (as known), but a tobacco smoke filter with radial smoke passage consisting of a tube of porous tobacco filter material closed at one end with a plug of smoke-impermeable material and having an outer tubular casing smoke-impermeable material surrounding the tube of tobacco smoke filter material at a distance.

The purpose of the initially stated process for the continuous manufacture of tobacco smoke filters is to provide a method by which the aforementioned new tobacco smoke filter, in particular cigarette filter, can be manufactured at high speed and reliably by simple means, i.e. very economical.

This object is achieved by the fact that the method of introduction initially is characterized by the characterizing part of claim 1.

In accordance with the claim 2, a particularly simple but reliable continuous method is obtained for accurately positioning the lengths of plug material without having to use a complicated apparatus for subsequent positioning in the longitudinal direction of the plugs, which would present difficulties in fast-working modern cigarette filter appliances.

The method of producing plug lengths as claimed in claim 3 fits particularly well with the requirements of rapid continuous filter production, avoiding the need for an intermittent separating mechanism for forming the plug lengths.

The closing step of claim 4 contributes to achieving a simple rapid operation of the apparatus. the heat-closing unit is part of a continuous continuous sequence from the previous to the next step and beyond.

The claim as claimed in claim 5 provides advantages of a similar nature as stated in claim 4.

Claim 6 discloses an alternative method of manufacturing the casing, in this case two sections which enclose the filter tube and plugs therein. This, in turn, is a simple operation that takes place during the continuous production of tobacco smoke filters.

Also, the steps set out in claims 7 and 8 of the process of the machine unit and the production of many filter lengths by separation are, of course, included in the continuous process for producing tobacco smoke filters.

In the process steps set out in claims 9 and 10, a change direction takes place as in other filters for making filters, with separate filter lengths from that point on being processed. By the measures set out in claims 9 and 10, it becomes possible to produce necessary seals (between the sleeve and the filter tube) by a simple operation, at which heat and pressure are applied without introducing additional steps of movement of the filter assemblies.

The invention further relates to an apparatus of the kind specified in the preamble of claim 11 for carrying out the method according to the invention. This apparatus is characterized by the characterizing part of claim 11.

The apparatus as claimed in claim 12 provides an apparatus for carrying out the method according to claim 5

The invention will now be described in more detail with reference to the drawing, in which: FIG. Figures 1 and 2 are longitudinal and cross-sectional views of a filter made in accordance with the invention; 3 and 4 are diagrammatic views of one embodiment of apparatus one used in the manufacture of such filters, respectively, from the side and top view; 5 is a side elevation view, on a larger scale, of a portion of the apparatus for producing plug material and for placing them on a filter paper strip; FIG. Fig. 6 is a horizontal section through a cross-head piece of mold for extruding and placing a casing around a unit formed by a filter tube and plug lengths; 7 shows a diagrammatic side view on a larger scale than FIG. 3 and 4 of a portion of the sealing device at the opposite end of the plug between the sleeve and the filter tube; FIG. 8 is a detailed view of FIG. 7, showing a side heating mechanism of the one shown in FIG. 7, FIG. 9 is a detail view of a central heating mechanism of the sealing apparatus of FIG. 7, FIG. 10 is a perspective view of one half of a casing to be inserted in another manner; FIG. 11 is a diagrammatic side view of another embodiment of an apparatus for producing tobacco smoke filters; and FIG. 12, 13, 14 and 15 are respectively a side view, an end view, a section along line XIY-XIY and a section along line XV-XV of FIG.

12 of another embodiment of an apparatus for producing lengths of plug material.

A single cigarette filter manufactured by the apparatus of the invention is shown in FIG. 1 and 2. It consists of a tobacco smoke filter paper tube 1 disposed coaxially within a tubular casing 2 made of a substantially smoke impervious resin or other material which can be softened, such as polyethylene, polypropylene. , ethylvinyl acetate copolymer, polyvinyl chloride, polystyrene, and cellulose acetate. It is conveniently made of polyethylene.

The tube 1 is positioned and supported in the casing 2 by longitudinal inner ribs 3 which are formed integrally with the casing at circumferential intervals. At the mouthpiece of the cigarette filter, the inner 4 of the filter tube 1 is closed by a short cylindrical or disc shaped plug 5 of substantially smoke-impermeable plastic material.

These plugs 5 can be made, for example, by extrusion, foaming or solid processing of polyethylene, polypropylene, ethylene vinyl acetate copolymer, nylon, polyurethane or cellulose acetate, e.g. of a white cellulose acetate rendered impervious to a high concentration of plasticizer. Preferably, the plugs 5 are made of polyethylene. At the end of the cigarette filter facing the smoker's mouth, a relatively narrow ring gap 6 is open between the filter tube 1 and the casing 2. At the opposite end near the tobacco rod of the cigarette (not shown), the inner 4 of the filter tube 1 is open, while the ring gap 6 is closed by a Inwardly inclined lip 7 on the casing 2. Such a lip can, as described below, be made using heat and welded together with the filter tube 1. However, the seal can be increased by adhesive, e.g. a polyvinyl acetate adhesive.

In one embodiment of an apparatus for practicing the method of producing tobacco filters, the filter is first known in lengths to produce four such filters, the lengths of which are then cut to the individual filters.

Referring to FIG. 3 and 4, a strip 10 of filter paper for the filter tube is supplied from a roll 11, a plastic rod material 12 is supplied with the plugs 5 from a roll 13, the plastic material for the casing 2 is supplied from an extruder press 14 and, if necessary, a paper strip for a conventional outer filter casing supplied from a roll 16.

From the roll 11, the strip 10 is passed through an applicator 17, at which two edges of the paper strip 10 are optionally provided with heat activatable adhesive to produce a longitudinal seam of a filter tube. Then, the paper strip 10 runs through a cooler 18 which makes the adhesive inactive, to a mechanism 19 for cutting predetermined lengths 5a corresponding to the lengths of two plugs 5 of plug material from the rod 12 and to place them on the strip 10 at predetermined intervals. Eg. in the case of a 20 mm filter the lengths 5a may be 5 mm and the interval 40 mm.

As shown in FIG. 5, the rod 12 arriving at the mechanism 19 passes between a feed roller 20 with a transverse sawing surface 21 at the rim and a guide roller 22 with a circular groove 23 of semi-circular cross section. It is propelled along a groove 24 in an adjustably arranged platform 25 towards the end of which the lengths 5a 145591 are cut by the rod by means of a rotary knife 26 of the well-known type in the cigarette industry and operating in a slot 27 in the platform 25. Pushed forward of the subsequent rod 12, each separated length 5a is gripped by a transfer wheel 28 and carried through a conductor 29 and past an electrically heated block to thereby be placed on the strip 10. In mechanism 19, the strip 10 carrying the plug lengths 5a is driven between a roller 51 having a circumferential groove 32 and a cylindrical roller 33. The rollers 20, 22, the knife 26, the wheel 28, and the rollers 31 and 33 are driven by a common axis at coordinated speeds, thereby producing the predetermined lengths 5a of plug material and placing them at their predetermined intervals on the strip 10. Separation of the plug lengths 5a is achieved by driving the wheel 28 at a higher peripheral speed than the rollers 20, 22. The heating the block 30 serves to activate the heat-sensitive adhesive with which the rod 12 is coated so that the plug lengths 5a adhere to the strips 10 where they are placed.

If required, the rod 12 can be supplied directly from an extruder to the mechanism 19. In addition, several plug lengths 5a may alternatively be arranged individually on the paper strip 10 at predetermined intervals by a conventional horizontal rotary thumbwheel.

The paper strip 10 carrying the lengths 5a of the plug material is then advanced through a forming unit 34 (Figs. 3 and 4) in which it is tubed in its longitudinal direction and a heating unit 35 at which the edges of the strip are closed together and the plug lengths are attached to the tube, followed by a belt conveyor unit 36. The units 34-36 may be of known kind as used to produce tubular paper casings by cigarette making or filter making machines. However, units 34 and 35 are preferably conceived to form the tube with a butt joint rather than an overlap joint.

The tube 10a thus produced, which consists of the strip 10 wrapped like a tube around the plug lengths 5a, is then provided with an extrusion cross-head mold with a tubular plastic material casing which forms the sleeve 2 for the final filters. Such a mold is shown in FIG. 6. The plastics material is supplied under pressure from the press 14 through a feeder tube 38, a split tapered distribution tube 38 'extending around a nozzle carrier 39 and annular passages 40, 40' to an annular mold opening 41 formed between an outer nozzle element 42 and an inner nozzle element 43. The tube 10a passes coaxially through the mold in bores 44, 44 'leading to the outlet 45 of the nozzle element 43. The plastic material is thereby extruded coaxially around the tube. To limit the friction, the bores 44 are larger in diameter than the tube 10a, and compressed air is advantageously blown into said bores to facilitate passage of the tube through the smallest bore 44 'which provides accurate conduction just before the extrusion site and to provide a cooling effect there. The ribs 3 (Figures 1 and 2) are formed by longitudinal grooves formed at 46 in the outer surface of the nozzle element 43 · The nozzle element 42 can be centered precisely with respect to the element 43 by a number of radial centering screws, one of which is shown at 47 The mold body is heated by electrical elements, one of which is shown at 48.

The tube 10b (Figs. 3 and 4) with the extruded casing then passes, with or without an outer casing strip 15, into a unit 49. If a strip 15 is not wrapped around the tube 10b, the unit 49 which can be removed within well known to the cigarette industry, mainly as a pull-off mechanism by means of a conventional unit band. If an externally wrapped strip 15 is provided, the unit also serves to form the strip around the tube 10b and to consolidate the entire tube. In the housing of the unit there is a cut-off mechanism operable at 50 which divides the pipe 10b midway alternately, not consecutive pairs of plug lengths 5a. The pipe 10b is thus divided into lengths 10c of 80 mm, when the filters must, for example, be 20 mm long, each comprising two double plug lengths 5a, each located 20 mm from the respective nearest cutting end. Each length 10c thus comprises material for four individual filter lengths.

The division at 50 into four filter lengths 10c is provided at the open ends (i.e., at the ends opposite the plug lengths 5a) of the two outer individual filter lengths. Division into individual filter layers is provided at a later stage, for example, in a manner known per se during assembly of filter cigarettes containing the filters.

9 145591

The cut lengths 10c are supplied individually to a chain conveyor 51 (Fig. 7), through which they are passed under a center-centered electric heater 52 (Fig. 9) with a dull knife edge 59 which is pressed into the depth of the casing 2 by its ribs to deform the sheath material in the paper tube to produce seals 7 at the two outermost single filters. the lengths 10c are arranged individually and across a conveyor belt 54 which feeds the conveyor 51. The latter consists of a pair of endless chains 55, each carrying a series of spaced-apart carriers 56 which hold the lengths 10c freely near the ends, but with some overhangs (Fig. 8) in recesses 57. The lengths 10c are driven away by the chains 55 in light contact with a fixed plate 58 so that they are forced to roll in the recesses 57 during the entire upper movement of the conveyor 51, and by passage below the heater 52, the two innermost adhesive seals 7 are made, as already described. The knife edge 59 does not separate the lengths 10c, but the tube 1 is left uncut. As shown in FIG. 8, each side heater 53 has a heat rib 60 with a narrow flat edge 61 which is pressed into the sheath material to produce the seal 7 of the filter at this end of the lengths 10c. The filter rod lengths 10c are finally released from the carriers 56 at 62.

In an alternative method of making the sheath 2, two strips of plastic material are extruded, each in cross-sectional form (Fig. 10) as half of the sheath 2 with flange-like surfaces 63 at the edges. The two extruded portions 64, 65 (FIG.

11) is joined together in a mirror-like manner around a filter paper tube 10a, in which the plug lengths 5a have already been inserted in the manner described above, between heated rollers 66 with peripheral grooves 67. The parts 64 and 65 are then formed around the tube 10a and closed together . The plates 63 are removed by rotating blades 68 which cooperate with rollers 69. The resulting tube 10b can then be treated in the manner previously described. Alternatively, the two parties 64, 65 could be closed together using adhesive.

According to another method of making the casing 2, wherein the ribs 3 are provided with a plurality of continuous strips, about half a millimeter wide, of plastic material, rigid paper or plastic wax which is applied transversely and spaced apart on a tape of smoke impermeable paper which already carries paper tubes and plug lengths such as 10a. This brand new tube connection is then passed through a unit used in conventional cigarette machines, whereby the tape is wrapped so around the paper tube that said strips form longitudinally supporting ribs corresponding to ribs 3. In this unit, the longitudinal edges of the tape are also joined together in a manner known per se. Annular inner ribs or projections of equal length along the tube may be provided in a similar manner.

Such ribs may also be placed at discontinuous rows of strips separated by lengths equal to the plug lengths. The strips may be arranged so as to form helical extending ribs. Strips may be formed in conjunction with a transverse strip which is brought into circular shape to serve as a seal between the sleeve and the filter tube.

Protrusions to support the filter tube may be formed on an intermediate tube member which is placed between the filter tube and the impermeable outer casing. For example, an intermediate element can be formed from a strip of thick paper perforated with longitudinal lines of holes or slots which may be arranged side by side or offset. The inner deformed edges of the holes or slots serve to separate the remainder of the element from the filter tube. Instead of being provided with holes or gaps, the intermediate member may be provided with inwardly projecting projections which are arranged correspondingly. The intermediate member may be provided with holes, slots or projections all over or rows of lengths interrupted by plane lengths equal to the plug lengths.

A protrusion with granules may also be formed which is adhered to the inside of a smooth casing. For example, a sheath's strip of impervious paper can be coated on what becomes the inside of the sheath with glue in a predetermined pattern, and coal granules sprayed onto the glue. Then the casing strip will be wrapped around the filter tube and adjacent granules will support the filter tube in the casing at an annular space between them. The coal will then add its effective filtration effect to the effect of the filter.

11 145591

According to another method of producing a smoke path which is equivalent to that formed by annular space 6, consists of a unit of a filter tube which already contains plug lengths and which is wrapped with a thicker layer formed by a strip of smoke-permeable, open cell foam, foam paper or low density paper. The unit thus produced is cut into filter lengths. A seal which is equivalent to the lip seal at 7 in FIG. 1, may be similarly manufactured or be formed with a sealing strip applied to the aforementioned layers before being tubed in a unit. Such a sealing strip can be made, e.g. of paper or cardboard covered with a polyvinyl acetate, a hot melt or similar adhesive or of a plastic material.

The plug lengths 5a can be prepared by methods different from those described above, e.g. as a string of plug lengths associated with predetermined spaces. In a suitable apparatus for this purpose shown in FIG. 12-15, a rod 70 of plastic plug material extruded with a diameter slightly larger than the diameter of the plugs 5 »in a heated state is inserted first between a pair of forming wheels 71, 72 and then between a pair of trimming wheels 73. 74, all operated together and at the same peripheral speed. The wheels 71, 72 are identical and are each provided with a series of recesses 75 with bottoms 76 of almost semi-circular shape with mutually equal and predetermined distances along the periphery. Corresponding recesses 75 in these wheels 71, 72 form rolling molds with which the plug lengths 5a are precisely matched. Between the recesses are areas 77 which are pressed out of the bar 70 into a smooth web formation 78. The wheels 73, 74 also have recesses 79 with the same circumferential distances and serve to receive the plug lengths 5a as they pass between the rollers. Between the recesses 79 there are areas 80, each of which at the upper wheel 73 has a sharp angular rectangular rib 81 and at the lower wheel 74 a complementary groove 82, in which the rib 81 passes tightly (Fig. 15). Corresponding regions 80 of the two wheels 73, 74 are sufficiently spaced apart to allow insertion of the web 78 between them. The rib 81 does not extend to the bottom of the groove 82. During the passage of a flat web 78 between the wheels 73, 74, marginal portions thereof are cut away between the sharp cooperating edges of the rib 81 and the groove 82, leaving only a narrow web 83 Between the plug lengths 5a. Marginal portions are also separated by the plug lengths 5a at the side portions of the sharp transverse edges 84 of the recesses 79, which can also remove any irregularity at the ends of the plug lengths 5a. Any edge of the plug lengths will be removed at the cooperating sharp edges 85 of the wheel 73 and the side washers 86 of the wheel 74.

Another method for producing a strip of plug lengths at predetermined intervals consists in extruding the plastic plug material into a cross-head mold around a core consisting of a higher melting point material than the extruded and by narrowing the extruded at said intervals.

The string of plug lengths produced is passed directly from the mechanism of FIG. 12-15 from the apparatus just described or from a wheel on which the strip is stored and deposited on paper strip 10 before entering the first forming unit 34 of the apparatus, similar to that of FIG. 3 and 4, but without the mechanism 19.

An alternative method of producing the seal at 7 (Fig. 1) consists in passing the tube 10b of sleeve filter tubes and plug lengths through a heater which serves to supply heat intermittently so that the sleeve is softened or partially melted to close the annular gap. at 7 at predetermined intervals in the tube.

According to another advantageous embodiment of the method according to the invention, such a tube as is produced, for example, in the embodiment of FIG. 3 and 4 lead to the unit 49, where the plug lengths are cut in the middle to obtain the individual filter lengths.

The annular space between the sleeve and the filter tube is then closed by adding to each section in mutual abutment a different nozzle or filter section in the form of a plastic material tube having a wall thickness corresponding to the radial dimension of the gap. Alternatively, another filter section used to close the annular gap may be made of a thermoplastic extruded open cell type foam having a hardened edge, the depth of which corresponds to the radial dimension of the gap, thereby providing a so-called double filter.

Claims (11)

13 145591 A method for continuously manufacturing tobacco smoke filters containing a tubular portion and a filter portion, at which plug-shaped portions are placed at predetermined distances on a strip-shaped portion, which is then converted into a tube, after which the tobacco smoke filters are obtained from the prefabricated filter tube by cutting, in that porous tobacco smoke filter material supplied in strip form (10) is applied to lengths of smoke impermeable plug material (5a), that tobacco smoke filter material strips (10) are shaped as a filter tube (at 34) which encloses the length of the smoke impervious plug material (5a), that the lengths of the plug material (5a) are adhered on one side with the tobacco smoke filter strips (10) and that their edges on the other side are adhered together (at 35) that a casing (2) is spaced apart from the filter tube (l) by securing the distance of the sheath (2) from the filter tube due to longitudinal ribs (3) on the sheath (2) and closing the filter tube (l) on the locations (7) opposite the filter end with the plug (5) closed. Method according to claim 1, characterized in that the lengths of the smoke-impermeable plug material (5a) are produced continuously in the form of a chain containing interconnected plug lengths (5a) connected to each other and thus placed on the strip (10) by porous filter paper that the individual plug lengths (5a), as a result of their interconnections, occupy their predetermined distances. Method according to claim 1 or 2, characterized in that the plug lengths (5a) are produced by a roll casting operation. Method according to claims 1-3, characterized in that the edges of the strip (10) of porous filter material, which are brought into tubular form around the plug lengths (5a) (at 34), are closely connected to one another in a heat-closing unit (35), preferably thus , thereby providing a blunt butt joint. Process according to claims 2-4, characterized in that the casing (2) is formed around the porous filter tube and smoke-permeable plug lengths (5a) continuously (10a) by extrusion in an extruder (extruder). ) crosshairs molded about (37) through which the unit (10a) is passed. Method according to claims 2-4, characterized in that the casing (2) around the unit consisting of porous filter tube and smoke-permeable plug lengths (5a) is continuously manufactured by joining pre-formed casing sections such that the unit (10a) is enclosed by these , wherein the edges (63) of the casing sections (64, 65) are closely interconnected (66, 67). Method according to claims 1-6, characterized in that the unit (10b) consisting of the casing (2), the porous filter tube and the smoke-impermeable plug length (5a) is passed through a machine unit (49), in which the first unit ( 10b) optionally provided with an outer casing (15). Method according to claims 2-7, characterized in that the unit (10b) of the casing (2), the porous filter tube and the smoke-impermeable plug length (5a) is divided by cutting to form several filter lengths (50). Method according to claims 2-8, characterized in that the closure (7) of the ring gap between the casing (2) and the porous filter tube is effected by deformation of the casing (2) on the porous filter tube with local protection (52, 59) and pressure application (53, 60, 61). Process according to claim 9, characterized in that the closure of the casing (2) is effected by rolling unit lengths (10c) consisting of the casing (2), porous filter tube and smoke-permeable plug lengths (5a) at a heating means (53, 60, 61 ), which is arranged such that pressure is exerted on this unit (10c) at the site (7) at which a closure of the casing (2) must take place. Apparatus for the continuous manufacture of tobacco smoke filters by the method according to one or more of claims 1-10, characterized by a machine (19 ... 27) for producing lengths of smoke impermeable plug material (5a),