Smoke filter containing particulate smoke modifying additiue

(42) Date of commencement of the patent: 15.10.1995 (45) Date of issue: 28. 5. 1996

<td>(30) Priority:</td><td>(73) Patent owner:</td>

<td>19.11.1990 GB 9025062 claims. 14.10.1991 GB 9121787 claims.</td><td>CIGARETTE CONPONENTS LIMITED SL2 4JN SLOUGH (GB).</td>

<td>(56) Documents:</td><td></td>

<td>DE 2406806A1 DE 3932891A1 EP 339482A2 GB 1528466A US 3,413,982A</td><td></td>

(54) PARTICULAR ADDITIVE FILTER AND USE (57) A filter or filter element in which at least one strip of particulate smoke modifying and adherent sorbent is precoated and wrapped around the longitudinal axis of the filter to form a tube at least 360 *.

AT 400 997

<img file="AT400997B_D0001.tif" />

D® 0 = 78018

AT 400 997 Β

The invention relates to a filter or a filter element, which is particularly suitable as a tobacco smoke filter.

Such filters are usually loaded with particulate smoke-modifying additives. Suitable particulate additives include sorbents (eg, selected from activated carbon, silica gel, sepiolite, alumina, ion exchangers, etc.), pH modifiers (eg, alkaline materials such as Na 2 CO 3, acidic materials), flavorants, or other solid additives, and mixtures of these.

By DE-OS 39 32 891 Sorbtions Additve have been proposed, which adhere to strips which are arranged within a conventional filter. In this case, these strips can be distributed over the entire cross section, or they form a central core of the filter. However, such filters require considerable manufacturing effort

The various known methods of making such filters have created production problems, problems of product quality control and product uniformity, and machine wear problems.

The aim of the invention is to propose a filter or a filter element that can be produced very easily.

According to the invention this is achieved in a filter or filter element by the characterizing features of claim 1.

A plurality of such overlying precoated strips may be looped 360 ° or more about the longitudinal axis to form the tube. In one embodiment of the invention, the pre-coated strip (s) are looped around a central core to be held in the tubular form.

In each embodiment, each strip may be provided on its two sides or on any side with particulate smoke-modifying additives adhering thereto.

The carrier strip or strips may be directly afflicted with the additive particles. Another possibility is to first glue the additive particles onto threads and then glue the coated threads onto the strip (s), eg glue the coated threads parallel and in lateral mutual contact.

Where two or more pre-coated strips are present, any two may be in side-by-side contact with each other (eg, strips of strips, strips of coating, or coating on coating) or separated from each other by an interposer.

The particulate additive is suitably by hot melt adhesive, eg high melting polyethylene glycol, or emulsion adhesive such as PVA to or the strips glued. Hot melt adhesives suitable for use in the invention are also various polyester adhesives. Each particulate additive may be a single substance or may be mixed with other materials. Where two or more stripes are used, different stripes may carry different additives. Where a strip is covered with additives on both sides, different additives can be used for the two sides.

The particulate additive that adheres to one side of the strip does not have to cover the entire area of ​​that page.

Where the filter or element is a tube surrounding a core or having the precoated strip, the core of a known smoke filter material, (eg fibrous yarn, fiber bundles or crepe paper), have a tube with open ends, or have an impermeable or poorly permeable region which contributes to the pressure drop across the composite filter but contributes little or nothing to the filtering action. The core may be a unitary body, or it may also have a composite structure, eg an own wrapping and / or or in longitudinal and / or or have radially adjacent parts. In one type of embodiment, where the tube surrounds a core, the particulate smoke modifying additives adhere to the inner surface of the tube surrounding the core, which itself may be surrounded by an outer annular member, such as the core can be made of a conventional smoke filter material, or an impermeable, or only slightly permeable part with little or no filtering effect.

Filters and filter elements according to the invention may comprise a wrapper, eg an extruded wrapper or a stopper wrapper with an overlapping seam. Such a plug wrap may be made of an air-permeable or air-impermeable material and in both cases may be perforated.

If the particulate coating strip (s) itself is coated with an adhesive (eg, with heat activatable adhesives), then the bond may be initiated when the tube is formed to form a bonded tube higher

AT 400 997 Β

To produce dimensional stability without a jacket, wherein the adhesive coating may be discontinuous (eg a powder coating) so that there is no undesirable interference with the smoke-modifying properties of the particulate additive. In another arrangement, an edge portion of the strip is kept free of particulate coating and provided with an adhesive to produce an adhesive overlap which maintains the strip wound into a tubular shape in the desired shape. Even if the, or the precoated strip (s) with its or whose edges are connected, or are, it is preferred to provide an envelope for the tube.

The, resp. the preformed strips coated with a particulate additive are conveniently formed into a tube by conventional means. In a method according to the invention, the supply of or the particulate additive carrying strip (s), whose, or their transformation into a tube (usually with the application of an enclosing envelope) and the cutting of such elongate product into certain lengths, continuously in line using conventional filter-making machines. To form the tube, the, or The strips can be placed around a central spine. Where the tube is to have a core, the core may be continuously advanced (or manufactured and advanced) to to wrap the particulate additive-carrying strips around the core, wherein, if the tube itself is to be surrounded by an outer annular body, the latter may similarly be fed continuously and formed around the advancing wrapped core. Continuous linear processes and devices for such processes are known in the manufacture of cigarette filters.

The, resp. the strips can be coated with an adhesive (eg by pulling through a bath, or applying an active adhesive) and then with particulate additive (eg by passing it through a supply, fluidized bed, circulating vapor or other carrier for the adhesive while it is active) as part of the above-mentioned linear process. However, the strips coated with adhesive can also be produced separately or obtained from a supplier, the activation (eg by softening by heat) of the adhesive and the application of the particulate additive in a linear process proceeds continuously with the filter production. A uniform application of the adhesive (eg from a bath of PVA liquid) can be ensured by doctoring, eg by passing through a slot or between one or more sounds. The particulate additive loading of the adhesive coated strip should be as heavy as possible, depending on various factors such as particle size, stripe width, etc. However, the additive load per strip can vary widely, as can the total load when two or more substrate strips are used according to the requirements of the product. Very heavy loading of the strips can result in elements consisting essentially of the particulate additive, without, however, having the disadvantage of the known types of particulate filter components and their method of preparation. Filters according to the invention may also comprise other materials.

Other parameters can also be varied within wide limits according to the requirements of the product. This includes, for example, the weight / length unit of the strip (s) used to support the particulate additive, the particle size of the additive, etc. One suitable particle size for activated carbon is 0.5 to 1.4 mm and another is 0.22 to 0.5 mm.

The strip (s) used according to the invention may be made of any non-toxic material. A strip may be of a textile material, such as a woven or non-woven tape or a cigarette filter plug wrap, and may be permeable or impermeable to smoke or air, according to the flow requirements of the final product.

At least some particles of the particulate additive used can carry or consist of flavors, or they can include other materials that carry flavors.

The invention permits the incorporation of activated carbon or other particulate additives into tobacco smoke filters using conventional equipment without resulting in manufacturing or machine problems and, in particular, achieving uniform additive loading and a simple and accurate change in loading as required. Filters according to the invention allow the particulate additive to the or to adhere to the strips which are unhindered, at least substantially unhindered, in their filtering action or other effects on the tobacco smoke stream. Filters according to the invention containing particulate sorbents may therefore well retain the vapor phase of smoke components.

Filters and filter elements according to the invention can be made continuously and cut into pieces of certain lengths. Each individual length of particular length may be used as a filter for a cigarette, but it is preferably in axial alignment with at least one other filter element as part of a composite (eg, a dual or

AT 400 997 B

Triple) cigarette filter is used with a common connecting outer sheath which extends circumferentially completely or partially around the composite filter and which may be permeable or impermeable to smoke or air. Preferably, a single filter element according to the invention is used in connection with a longitudinally oriented mouthpiece of conventional shape, eg a uniform plug of cellulose acetate fiber yarn. In this case, these two parts may abut one another or be distanced from one another in order to limit an intermediate space through which air flows and / or or may contain additive granules.

Products of the invention are generally suitable for use as tobacco smoke filters, but although the invention has been described primarily in the context of such filters, it is not limited to such use and also includes products themselves, however they may be used. Cigarette filters according to the invention are usually attached to a wrapped tobacco rod by a conventional wrapper that may be vented or not ventilated.

Embodiments of the invention are illustrated in the accompanying drawings, for example, in which Figs. 1 to 10 show sections of various embodiments of the invention. In the drawings, like reference numerals are used for like parts.

Figure 1 shows a tubular filter or filter element comprising a strip of plug wrap 2 pre-coated with activated carbon particles 4, adhered to one side of the strip and deformed to form a tube, the particles 4 being on the outside of the tube. At 6 there is provided an adhesive edge of the strip, free of particles 4, which forms an overlapping seam with the outer edge of the strip so that the filter is held in its tubular shape. Alternatively, the particles 4 may also stick to the other side of the strip 2 forming the inner side of the tube, or the particles 4 may adhere to both sides of the strip 2. Other possible variations are that the strip 2 is wound over a core and / or or the placement of an enveloping wrap around the tubular structure.

FIG. 2 shows a similar embodiment in which a tube, as shown in FIG. 1 is shown having an outer layer formed by another strip of plug wrap 2 adhered to the particles 4 and wound around and in contact with the innermost tube with the two particulate coatings 4, the outer layer being in the same Way is held in a tubular shape by a particle-free held overlapping seam. The in connection with the Fig. Variations explained in the embodiment according to FIG. 2 also be applied.

FIG. 3 shows a tubular filter or filter element, which is formed from a strip of a plug envelope 2, which filter is coated on both sides with adhering to this absorbent particle 4. One side of one edge region and the opposite side of the other edge region of the strip 2 are kept free of particles but are adhesively coated so that they can form an overlapping seam 6 to hold the product in a tubular shape. An additional layer or layers of the strip 2 coated with particles 4 on one or both sides and placed around the structure shown and the other variations described above (the arrangement of a core and / or or an outer cover) may also be provided.

FIG. 4 Figure 4 shows a filter having a strip of plug wrap 2 to which particles of sorbent 4 adhere and which is wound around a tubular core 8 with the particles 4 facing the core 8 and the coated strip 6 with one of particles as already mentioned kept free overlapping seam 6 is secured. The strip 2 may instead or in addition be coated on its outside with particles 4, wherein one or more additional enclosing layers of the strip 2 may be provided with adhering to these particles 4.

FIG. 5 Figure 3 shows a strip of plug wrap 2 adhering to one side particles 4 of a sorbent and wrapped around a conventional filter plug 9 with the particles on the outside. In this case, the edges of the strip 4 may abut each other and adhere to the plug 9. Instead or in addition, the illustrated filter may be provided with an enclosing plug wrap. As in the previously described embodiments, the particles 4 may adhere to both sides of the strip 2 and to one or more additional layers of particle 4 coated strips 2, which strips 2 may have one or both sides coated thereon.

FIG. 6 shows an embodiment similar to that of FIG. 4, except that the core is formed by a plug 10. The longitudinal edges of the precoated strip 2 may also butt against each other, in which case the coated strip may adhere to, for example, the core or an outer wrap to be held in the form of a tube. The adhering particles 4 may cover less than the surface of the strip 2, eg Both longitudinal edge regions of the strip can be kept free of particles 4 of the additive if these longitudinal edge regions form an overlapping seam 6. The core 10 may, as shown in FIG. 5, be a conventional filter plug, or a

AT 400 997 Β impermeable or poorly permeable plug, which increases the pressure drop and has little or no filtering effect. The illustrated embodiment may optionally include an enclosing enclosure 20, which may be formed by an extruded wrapper or a conventional plug wrap with an overlapping seam.

FIG. 7 shows a structure according to the type of FIG. 6, in which the core 10 and the surrounding coated strip 2 itself are again surrounded by an annular body 12. In this case, the core 10, for example may be formed by a filter plug of cellulose acetate yarn, wherein the strip 2 may be an impermeable plug wrap on the inside of which activated carbon particles adhere, the outer annular body 12 being formed of cellulose acetate yarn held in a highly porous outer wrapper to achieve a high level of aeration ,

FIG. 8th shows (in a longitudinal section, instead of in a cross section as the previous figures) a composite element according to FIG. 7 combined with a dual filter with a filter plug 16 of unwound cellulose acetate yarn held in a conventional porous plug wrap 18. Such a dual filter according to the present invention may be incorporated into a cigarette containing the tobacco rod, the additive containing member, and the non-wound acetate member facing the mouthpiece.

FIG. 9 shows a cross section of a filter or filter element of the type shown in FIG. 6, but in which the additive-coated strip 2 is surrounded by another surrounding strip of a plug casing which is coated with particulate additive 24 and is in tubular form (eg by an overlapping seam 6) in which the additive 24 is held radially inward. As shown in FIG. 6 optionally, an outer enclosure 20 may be provided as part of the composite product. The particulate additives 4 and 24 may be the same or different.

A similar embodiment can be achieved by using a core 10, a strip 2 according to FIG. 3 (on both sides with particulate additive adhering to it), an (additive-free) plug casing 12 and optionally, as explained above, an outer casing 2 is surrounded, be provided.

FIG. 10 shows a longitudinal section through a composite element 26 of FIG. 6 or 9 incorporated in a triple filter comprising a filter plug 16 of non-wound cellulose acetate yarn (hereinafter referred to simply as NWA) in a conventional compound plug wrap. As can be seen, the element 26 has a core 10 which is supported by only one strip 2 (with particulate additive 4 adhering to it) and a surrounding envelope 20, as shown in FIG. 6, is surrounded, but also the structure of FIG. 9 with an additional tubular strip 22 and additive particles 24 may have. The filter according to FIG. 10 may be made of a continuously produced bar by forming a strip of end-to-end abutting elements, which bar is made of elements 26 alternating with double-length NWA elements, as shown at 16, which are continuously indexed As this rod is wrapped with a common sheath 18 and the continuously produced rod is cut in the area of ​​the NWA elements. Usually, the rod is initially divided into pieces that correspond to a multiple of the length of a single filter (Fig. 10), (eg in pieces of twice, four or six times the length of a filter), the final cutting being subsequently carried out as part of the manufacture of the cigarettes. A similar method can also be used in the embodiment according to FIG. 8th used - eg with a first division in the area of ​​the composite elements - in order to obtain rods with a multiple length and a further division in the area of ​​the inner elements by the partial lengths in the assembly of the filter cigarettes. The multi-length rods correspond to the invention.

In the following examples, the pressure drops are measured fully closed, eg with a cylindrical surface of the test piece surrounded by an impermeable shell, to prevent flow across the outer skin of the test pieces.

example 1

Filter according to FIG. 10.

The NWA elements 16 have a length of 5mm, a circumference of 22.75mm and a yarn or cable denier of 1.5 / 38, with the pressure drop (hereinafter referred to as PD for short) being 83mm water gauge (WS).

The composite members 26 were 10mm long, 22.1mm in circumference, and had a core 10 of cellulose acetate with a yarn or cable denier of 2.1 / 30. The strip 2 was of a non-porous plug wrap and had a width of 23 mm and was loaded with particles of activated carbon 0.4 to 0.85 mm particle size with a loading of 5.4 mg / mm, which particles

AT 400 997 Β the strip (shown in FIG. 6) were glued with PVA glue. An enclosing outer wrap 20 was passed through a 25mm wide plug wrap which had a porosity of 5000 Coresta units. The pressure drop of element 26 was 225.5 Pa.

For a triple filter, as can be seen in Fig. 10, elements 16 and 26 were combined with each other by means of a plug wrap 18 whose porosity was also 5000 Coresta units and elements 16 were easily pressed through the plug wrap. The triple filter was 20mm long with a circumference of 22.46mm and caused a pressure drop of 1039.5 Pa and had a carbon content of 54mg.

These triple filters were attached to commercial cigarette rods by means of permeable tip sheaths. The resulting cigarettes were smoked when tested in accordance with the standardized ISO / Coresta method, which gave a tar retention of 55.2% and a nicotine retention of 44.8% over cigarettes without filter and the following vapor-phase restraint:

<td></td><td>%</td>

<td>methanol</td><td>17.5</td>

<td>Acetaldehyde</td><td>4.8</td>

<td>acetonitrile</td><td>21.8</td>

<td>Akroleine</td><td>15.0</td>

<td>isoprene</td><td>18.3</td>

<td>Butadione</td><td>38.0</td>

<td>butanone</td><td>29.9</td>

<td>Benzene</td><td>28.2</td>

<td>Toluene</td><td>42.2</td>

Examples A to L

In Examples A to J and L, Example 1 was repeated using various particulate additives and with other variations to be mentioned later. In Example K, a further modification was provided according to which the element 26 corresponded to the element shown in FIG. 9.

The triple filters had a 6mm long NWA element and a 12mm long element 26 (hereafter "ACS") in a standard plug wrap 18 of a 27g / m substance^{* 2} on. The NWA elements had 1.6 / 48 yarn or cable denier with a normal circumference of 24.8mm.

In ACS element 26, Examples A to L 8/39 denier cellulose acetate yarns were used for the core 10, 27mm long plug wraps (having a porosity of about 7,500 Coresta units) for the strip with various particulate additives 4 based on adhered to the strip of Example 1. The enclosing wrap 20 was from a standard 27g / m² Plug wrap.

Other details of the ACS elements 26 and the triple filters are given in the following table. In the additive column C stands for activated charcoal and the numbers for the mesh size - eg C 12/22 means activated carbon of 0.71 to 1.4 mm grain size. The mixed particulate additives of Examples F and G contained a 2: 1 weight ratio of activated carbon of 0.71 to 1.4 mm particle size and sepiolite of 0.5 to 1 mm particle size. In Example K, a strip 2 with activated carbon 0.22 to 0.5 mm particle size was loaded on the inside, which strip, as shown in FIG. 9 could be seen, immediately surrounded by another strip 22, on the sepiolite shown in FIG. 9 24, similarly adhered to the inside thereof, the latter strip being wrapped by an enclosing envelope 20.

In modifications of the embodiments of FIG. 10 and Examples 1 and A to L, the enclosing enclosure 20 may be omitted, however, the element 26 must have a size which ensures connection to the enclosure 18.