EP1796488B1 - Tobacco smoking filter or filter element with a content of adjuncts - Google Patents

Abstract

A tobacco smoking filter is disclosed, with adjunets on the surface in the form of fibres filaments or films and whereby the drawing resistance of the tobacco smoking filter and the mass of the adjuncts in the tobacco smoking filter meet the following equation (I) M<SUB>ad</SUB>/Deltap>1 mg/daPA (I), where Deltap is the drawing resistance [daPA], applied as a value calculated with a 7.8 mm filter diameter and M<SUB>ad </SUB>[mg] is the mass of the adjuncts. The tobacco smoking filter comprises channel structures and the filer material is provided as a planar material. Said tobacco smoking filter has a low draw resistance on smoking with a particularly good filtration effect and is relatively simple to produce.

Description

The invention relates to tobacco smoke filters or filter elements which are constructed in one piece and contain fibers, filaments or films based on spinnable or film-processable polymers or polymer blends and one or more additives.

Tobacco smoke filters of the above type are known in the art. It should be understood by "one piece" that the tobacco smoke filter are constructed in a uniform longitudinal-axial direction and can be made without further limiting filter elements. Here, there is a significant difference to what are termed "chamber filters" in which a chamber bounded outwardly by a wrapping paper, which may be filled by additives such as granular activated carbon, is provided between longitudinally spaced filter elements of conventional filter material.

There has been no lack of attempts to design filter constructions that allow particularly efficient use of porous additives. The mentioned chamber filter construction has disadvantages in the efficient use of the activated carbon involved. Because of the limitation of the degree of filling of the chamber and the relatively coarse grain of the activated carbon part of the smoke flows through the unfilled part of the chamber and thus does not come into direct contact with the activated carbon. The particle size of the activated carbon can not be arbitrarily reduced, as this would have an unacceptable increase for the smoker increase in draw resistance. In this regard, the cheaper behaves in the EP-A-014477 described filter construction, is scattered in the granular activated carbon in a filter element in a manner that an approximately homogeneous distribution of the activated carbon particles in the themselves homogeneously distributed fibers or filaments of the filter material is ensured. Although by-pass formation can be precluded in this way, coarse-grained additives are required to ensure fixation of the said particles in the tobacco smoke filter. The described disadvantages of the coarse-grained activated carbon are therefore also evident in this filter construction.

For tobacco smoke filters or the use and as background for the invention described below, the following should be noted: filter cigarettes are on their mouth side End provided with tobacco smoke filter that captures at least a portion of the combustion products of the tobacco of the cigarette and thereby prevents the combustion products are inhaled during smoking. On the other hand, a tobacco smoke filter should influence the taste of the tobacco smoke so that it is judged by the smoker to be positive. In a part of the filter cigarettes, the tobacco smoke filter is mixed with a porous, particulate additive which increases the filtration performance of the tobacco smoke filter or the tobacco smoke filter elements compared to a tobacco smoke filter without particulate additives. Often, this effect can be explained by the fact that the porous additives preferably adsorb gaseous combustion products on their inner surface and thus reduce their concentration in the smoke. In the most prominent representatives of this type of cigarette filters is used as a porous, particulate additive activated carbon. Other such tobacco smoke filters, such as those in the DE-A-2 658 479 contain oxides, hydroxides and / or oxide hydrates of various metals, such as silicon, aluminum, magnesium, iron and / or titanium. Critical to the effectiveness of such porous, particulate additives is their accessibility to the gaseous smoke ingredients. Thus, it has been found that, in particular, finely divided porous materials show an increased filter performance compared to coarser particles. Other disadvantages of the above-mentioned chamber filter can be seen in the fact that they require a lot of effort in their production.

Other known filter constructions show ways to include even fine-grained additives in the tobacco smoke filter. The US-A-3,043,736 and the US-A-2,881,770 describe a tobacco smoke filter from a bundle of endless, crimped filaments of cellulose acetate, which is summarized by a wrapping paper to a filter rod, wherein the individual filaments are coated with finely divided activated carbon. The possible devices for application of the finely particulate additives can be classified into devices a) for applying the additive from a slurry in an aqueous phase or a volatile organic carrier or plasticizer fluid, b) for inflating the small particle additives previously mentioned c) for application of a latex emulsion; and d) for applying the additive by passing a bundle of filaments or filaments previously wetted by adhesive or plasticizer through a fluidized bed of finely divided activated carbon. In this regard, please refer to the DE 127 4 946 ,

The tobacco smoke filters produced by the above methods are characterized in that the filaments loaded with additives are preferably oriented longitudinally and mutually bound to each other at randomly distributed contact points by the action of an adhesive or plasticizer, so that evenly distributed over the filter substantially longitudinal small spaces be created between adjacent filaments by the flow of tobacco smoke.

The stated embodiments illustrate that the tobacco smoke filter thus produced and offset by particulate additives have similar high tensile resistances as the comparative filter without incorporation of particulate additives. Consequently, according to these methods, it is not possible to produce filters which have the same high additive mass as low draw resistances.

Alternatively, filter filters doped with activated carbon in tobacco smoke filters are used. These include small particle size activated carbons that are bound to the paper during the papermaking process. Here, a fabric is produced by the manufacturer of the filter material, rolled on reels and then sent to the processor. The filter or cigarette maker rolls the material off the reel, forming it into a rod-shaped product, then transaxially compressing it in the format part of the filter rod machine, wrapping it with paper and cutting it to the final length of the filter rods. In addition, the fabric is usually, but not necessarily, crimped before forming into a rod parallel to the direction by a creping device. On the one hand, this achieves a reduction in the material density and, on the other hand, an influence on the draft resistance of the filters. Characteristic of such filters produced by pleating of sheet materials is their channel structure in which longitudinally channel-shaped regions of low material density extend over a substantial portion of the length of the filter or filter element. These channels are limited by the filter material with a higher material density. This structural property is essentially due to the comparatively low draw resistance of these filters.
When using these surface filters, which are not or only partially made of cellulose acetate, however, the smoke flavor is often judged to be negative. In addition, such filters do not exhibit the specific retention performances for phenols or nitrosamines known from the cellulose acetate cigarette filters.

The invention was therefore based on the object at the outset designated integrally constructed tobacco smoke filter or filter elements so that the effectiveness of incorporated finely divided adsorbents is impaired as little as possible and yet at associated high mass of the particulate additives, a lower draw resistance, in particular as a filter material used cellulose acetate shall be.

According to the invention, this object is achieved in that a) the additives are present on the surface of the fibers, the filaments or the films, b) the draw resistance of the tobacco smoke filter and the mass of the additives in the tobacco smoke filter comply with the following formula (I): M _ad / Δp > 1 mg / daPa (I), where Δp is the draw resistance [daPa], which is used as a value converted to 7.8 mm filter diameter, and M _ad [mg] is the mass of the additives, c) the tobacco smoke filter has channel structure and d) the filter material is present as a flat structure.

In the context of the invention, it is possible to use customary fibers, filaments and films based on spinnable or film-processible polymers or polymer blends. In the context of the invention, it is preferred that the filter material is a flat structure of fibers or filaments or a film, wherein the sheet-like structure and / or the film are smooth, pleated embossed and / or partially compressed.

berechnet wird, worin bedeuten m_A die Fasermasse [g], ΔP den Zugwiderstand [daPa] und dpf den Filamenttiter (dtex) und für den Zugwiderstand der auf den Filterdurchmesser von 7,8 mm umgerechnete Wert eingesetzt wird, und die Härte des Zigarettenfilters 90 Filtronahärte überschreitet.It is particularly preferred if the filter material is made up of a cellulose ester, in particular cellulose acetate, cellulose butyrate, cellulose acetobutyrate, cellulose acetopropionate and / or cellulose propionate being suitable as cellulose esters. A particularly preferred cellulose acetate has a degree of substitution of 1.5 to 3.0, especially 2.2 to 2.6, more preferably 2.5. It has proven to be particularly advantageous to use a tobacco smoke filter in the context of the invention or in its realization, which in the WO 01/28369 is described. With slight modification and further optimization of the present invention, it is preferable that the filament-to-filament-to-filament draw resistance ratio S is greater than 0.7, the S value being of the formula $$\mathrm{S}\mathrm{=}\left({\mathrm{m}}_{\mathrm{A}}\mathrm{/}{\mathrm{Ap}}_{\mathrm{7}\mathrm{.}\mathrm{8th}}\right)\mathrm{/}\mathrm{dpf}\left[\mathrm{10}\mathrm{m}\mathrm{/}\mathrm{daPa}\right]$$

where m _{A is} the fiber mass [g], ΔP is the draw resistance [daPa] and dpf is the filament titer (dtex) and draw resistance is the value converted to the filter diameter of 7.8 mm, and the hardness of the cigarette filter 90 Filtrona hardness exceeds.

worin bedeuten m_A die Fasermasse [g], G den Gesamttiter [g/10 exp 4 x m] sowie l die Filterlänge [mm].Furthermore, it is preferred here that the fiber mass is at most 10 mg / mm filter length and / or the residual crimp of the filter material does not exceed the value of 1.45, for which the following formula (III) applies: $${\mathrm{I}}_{\mathrm{R}}\mathrm{=}\mathrm{10000}\mathrm{\times }{\mathrm{m}}_{\mathrm{A}}\mathrm{/}\left(\mathrm{G}\mathrm{\times }\mathrm{I}\right)$$

where m _{A is} the fiber mass [g], G is the total titer [g / 10 exp 4 xm] and l is the filter length [mm].

Optimum residual crimping is between about 1.05 and 1.4, in particular between 1.1 and 1.3. Furthermore, it is preferred that the fiber or filament mass draw resistance ratio S related to the filament titer is at most 2, in particular between 0.8 and 1.3.

Particularly advantageous results are achieved with the tobacco smoke filter according to the invention if the fiber or filament mass is at least 4 mg / mm filter length, in particular between 5 and 8 mg / mm filter length.

With regard to the optimization of the Filtrona hardness, it can be stated that it should preferably be between 90 and 95, in particular between 91 and 93.

In the context of the invention, the additives that are essential for the solution of the problem, are arranged on the surface of the fibers, the filaments or the films. In this case, it is particularly preferred if these additives are particulate, in particular have a particle size of less than 300 microns, in particular less than 100 microns. It is particularly preferred if the particle diameter is less than 50 microns, with a particle size of less than 30 microns leads to particularly good results. When selecting the particulate additives or the porous additives, the invention is not subject to any significant restriction.

It is readily possible for the person skilled in the art to select the suitable additives, these preferably being in the form of an adsorbent based on activated carbon, metal oxides, metal hydroxides and / or metal oxide hydrates, in particular those of aluminum, silicon, titanium and / or magnesium is. In individual cases, it is preferred if the porous additive is additionally mixed with active substances, in particular in the form of antioxidants, flavors and / or antimutagenic substances.

The incorporation of the particulate additives into the tobacco smoke filter of the invention is not critically limited. Nevertheless, it is preferred that the particulate additives are fixed by means of a binder on the surface of the filter material, in particular with polyvinyl acetate, polyvinyl alcohol, polyethylene glycol, water-soluble esters or ethers, starch, starch derivatives and / or cellulose esters.

The surface of the fibers, filaments and films can be further optimized as follows: Thus, the additive thereon can fulfill the function of a filtration aid, in particular in the form of organic acids, acidic carboxylic esters, polyphenol and / or porphyrin derivatives. The fibers, filaments and films of the film material or the fibers, filaments or films constituting the tobacco smoke filters or filter elements may contain further additives in the interior which improve their properties. These are preferably plasticizers, matting agents, pigments and / or stabilizers. Of particular importance is the inclusion of the plasticizer. In this case, it is preferred that this be present within the fibers or filaments or films in an amount of 0 to 15 wt .-%, in particular from 5 to 12 wt .-%. The plasticizer is expediently present as triacetin, ethylene glycol diacetate and / or diethyl citrate. In addition, the tobacco smoke filter according to the invention may also contain a photoreactive additive, in particular in the form of finely divided anatase-type titanium dioxide having an average particle size of less than 2 μm.

A particular feature is given by the feature b) of the teaching defined above according to the invention. Thereafter, it is a requirement of the invention that the draft resistance of the tobacco smoke filter and the mass of additives in the tobacco smoke filter comply with the following formula (I): M _ad / Δp _7.8 > 1 mg / daPa, where Δp [daPa] is the draw resistance, the as a converted to 7.8 mm filter diameter Value is used, and M _ad [mg] is the mass of the additives. It is particularly preferred if the ratio of M _ad / Δp is above 2 mg / daPa, in particular above 3 mg / daPa.

Another essential feature of the invention is the channel structure of the claimed integrally constructed tobacco smoke filter or filter elements. It should be noted that in a channel structure, channel-shaped regions of lesser material density extend longitudinally over a substantial portion of the length of the filter or filter element. These channels are limited by the filter material with a higher material density. The channel structure is maintained in particular by using a flat structure according to the invention as the filter material.

It is easily possible for a person skilled in the art to produce the integrally constructed tobacco smoke filter or the tobacco smoke filter elements constructed in one piece without further additional technical information. In the following, a particularly suitable method will be discussed: In this case, filter tow is removed from the bale for the production of the tobacco smoke filter according to the invention, pneumatically processed and drawn according to the method customary for space filters. Before the actual activation step, a non-woven nonwoven with the highest possible strength in the direction of both surface axes is generated as an intermediate, which can be wound up on spools and applied with additives. Any suitable method of producing the tobacco smoke filter may be used to distribute powder onto a fibrous surface. Particularly suitable are the devices a) for applying the additive from a slurry in an aqueous liquid or a volatile organic carrier or plasticizing fluid to the filaments to which a binder may have been added, and b) for inflating the particulate additive on the threads, which may have previously been wetted with an adhesive or a plasticizer. Alternatively or additionally, the adhesion of the particulate additives can be ensured by a hot melt adhesive, which is either applied together with the particulate additives or applied separately or activated by brief heating.

The tobacco smoke filters according to the invention can be produced continuously from filter rods and cut in a limited length. Each individual element of such limited length could by itself serve as a tobacco smoke filter for a cigarette however, it is preferably used in longitudinal alignment with at least one other filter element as part of a composite (eg, double or triple) cigarette filter. Preferably, a single filter element according to the present invention is used in conjunction with a longitudinally aligned mouthpiece element of conventional appearance, for example, a unitary rod of cellulose acetate fiber cable.

The advantages associated with the present invention can be summarized as follows: It has thus been found that finely divided additives can be introduced into tobacco smoke filters while maintaining the teaching according to the invention, wherein, unlike the corresponding comparative products of the prior art particularly low draw resistance is observed during smoking. It has been found in the filters according to the invention that such a particularly high or high filtration performance can be achieved.

Moreover, the one-piece tobacco smoke filter of the present invention is relatively easy to manufacture compared to the corresponding comparative products of the prior art. This eliminates the costly production of said chamber filter of several filter elements. Another advantage is that, especially when the filter material is made of cellulose acetate, the smoky taste is judged to be particularly positive. Also, the selective retention effect with respect to phenols is observed.

The invention will be explained in more detail by way of examples.

Example 1 (Production of a filter according to the invention)

A filter tow of specification 2.1Y48 (filament denier 2.33 dtex, total titer 53 333 dtex) is prepared on a conventional two-stage drafting system KDF 2 from Hauni, Hamburg, and sprayed with 8% triacetin. After leaving the guide roller, the filter tow web is inserted with a minimum width of 250 mm in a pair of heated calender rolls and calendered with an effective line pressure of 40 kg / cm. The profiled calender rolls have a diameter of 230 cm and a grooved width of 350 mm and have 10 tread grooves per cm, while the other is unprofiled. They are heated with a silicone oil to 150 ° C. The groove profile is trapezoidal with an upper width of 0.4 mm and a depth of 0.5 mm.

After leaving the calender rolls, the nonwoven thus produced is wound up on a spool. Such a nonwoven spool is unwound continuously on a conventional padder and passed through a liquor which is filled with an aqueous activated carbon suspension. In this case, we immersed the fleece down to 5 cm in the suspension and deflected at a deflection roller upwards. After leaving the suspension bath, excess suspension is squeezed off on a pair of nip rolls. The squeegee rollers are driven at 10 m / min and thus ensure a uniform movement of the web through the suspension. After leaving the nip rolls, the nonwoven is passed through a circulating air dryer at 150 ° C. The dryer has a drying section of 4 m and thus ensures the drying of the suspension and the fixation of the activated carbon on the nonwoven.

After leaving the dryer, the nonwoven fabric doped with activated carbon is strand-folded on a commercially available KDF 2 from Körber, Hamburg, by insertion into an inlet nozzle, wrapped in paper and cut to a filter rod length of 126 mm. The diameter of the filter rods was set to 7.8 mm.

Comparative Example 1 (Preparation of an Activated Carbon Filter by Scattering of Coal Particles in Filter Tow)

A filter tow of specification 2.1Y48 (filament denier 2.33 dtex, total titer 53 333 dtex) is prepared on a conventional drafting system KDF 2 from Hauni, Hamburg, and sprayed with triacetin. After leaving the guide roller, the filter tow web is passed with a minimum width of 200 mm through a spreader and pneumatically treated with activated carbon particles of about 250 micron particle size. For this purpose, the activated carbon powder is metered onto a suction nozzle with a metering balance continuously and blown by compressed air through a pipeline to the spreader nozzle. The spreader nozzle is preferably encapsulated with a suction box provided with only openings for the supply and removal of the filter tow web to avoid leakage of coal dust into the environment. By matching the amount of activated carbon delivered to the speed of the filter tow web, the amount of activated carbon on the filter tow web can be set very accurately become. After leaving the described device, the filter tow web is strand-shaped folded in an inlet nozzle and in a commercial KDF 2 of the Fa Körber, Hamburg; wrapped with paper at a speed of 50 m / min and cut to a filter rod length of 126 mm. The filter rod diameter is set to 7.8 mm.

The table summarizes the results of drag resistance and activated carbon tests. particle size dpf G activated carbon draw resistance M _ad / Δp activated carbon [Dtex] [Dtex] Dimensions (Filter plugs) [Mg / daPA] [.Mu.m] [mg pro [DaPA] 21 mm film terstöpsel] Comparative Example 1 250 2.33 53333 80 131 0.61 example 1 20 2.33 53333 80 10 8.0

Claims (24)

1. Tobacco smoke filters or filter elements constructed in one piece and containing fibers, filaments or films based on polymers or polymer mixtures, which can be spun or processed into films, and at least one additive, wherein the at least one additive being on the surface of the fibers, filaments or films, characterized in that

   a) the at least one additive is particulate,

   b) the resistance of the tobacco smoke filter to the passage of air and the mass of the at least one additive in the tobacco smoke filter observe the following formula (I): $${\mathrm{M}}_{\mathrm{ad}}\mathrm{/}{\mathrm{\Delta p}}_{\mathrm{7}\mathrm{,}\mathrm{8}}\mathrm{>}\mathrm{1}\mathrm{mg}\mathrm{/}\mathrm{daPa}$$

   

   
   in which Δp_7.8 is the resistance to the passage of air (daPa), which is used as a value calculated on the basis of a 7.8 mm filter diameter, and M_ad (mg) is the mass of the at least one additive,

   c) the filter material is present as a two-dimensional formation.
2. The tobacco smoke filter of claim 1, characterized in that the filter material as a two-dimensional formation of fibers, filaments or films is smooth, folded, embossed and/or partially consolidated.
3. The tobacco smoke filter of claims 1 or 2, characterized in that the filter material is built up from a cellulose ester.
4. The tobacco smoke filter of claim 3, characterized in that the cellulose ester is cellulose acetate, cellulose butyrate, cellulose acetobutyrate, cellulose acetopropionate and/or cellulose propionate.
5. The tobacco smoke filter of claim 4, characterized in that the cellulose acetate has a degree of substitution of 1.5 to 3.0 and, in particular, of 2.2 to 2.6.
6. The tobacco smoke filter of one of claims 1 to 5, characterized in that the ratio of M_ad/ Ap_7.8 is more than 2 mg/daPa and, in particular, more than 3 mg/daPa.
7. The tobacco smoke filter of one of claims 1 to 6, characterized in that the at least one particulate additive being on the surface of the fibers, filaments or films, in particular has a particle size of less than 300 µm.
8. The tobacco smoke filter of claims 1 to 6, characterized in that the particle size of the at least one additive is less than 100 µm, preferably less than 50 µm and, in particular, less than 30 µm.
9. The tobacco smoke filter of claims 7 or 8, characterized in that the at least one particulate additive is a porous additive; in particular, in the form of an absorbent based on activated charcoal, metal oxides, metal hydroxides and/or metal oxide hydrates.
10. The tobacco smoke filter of claim 9, characterized in that the metal oxides, hydroxides and/or metal oxide hydrates are those of aluminum, silicon, titanium and/or magnesium.
11. The tobacco smoke filter of claims 9 and 10, characterized in that active substances are added to the at least one porous additive, in particular, in the form of antioxidants, flavors and/or antimutagenic substances.
12. The tobacco smoke filter of at least one of the preceding claims, characterized in that the at least one additive being on the surface of the fibers, filaments and films, is a filtration aid, in particular, in the form of organic acids, of acidic carboxylic esters, of polyphenol and/or of porphyrin derivatives.
13. The tobacco smoke filter of at least one of the claims 1 to 12, characterized in that the at least one particulate additive is fixed on the surface of the filter material by means of a binder, in particular, with polyvinyl acetate, polyvinyl alcohol, polyethylene glycol, water soluble esters or ethers, starch, starch derivatives and/or cellulose esters, in particular, cellulose acetate with an average degree of acetylation of 0.3 to 1.
14. The tobacco smoke filter of at least one of the claims 1 to 13, characterized in that the fibers, filaments or films of the film material contain further additives in their interior to improve the properties.
15. The tobacco smoke filter of claim 14, characterized in that the further additives are plasticizers, marking agents, pigments and/or stabilizers.
16. The tobacco smoke filter of claim 15, characterized in that the plasticizer within the fibers or filaments or films is present in an amount of 5 to 15% by weight.
17. The tobacco smoke filter of claims 15 or 16, characterized in that the plasticizer is present in the form of triacetin, ethylene glycol diacetate and/or diethyl citrate.
18. The tobacco smoke filter of at least one of the preceding claims, characterized in that the fiber mass (or filament mass) - resistance to the passage of air - ratio S, related to the filament titer, is larger than 0.7, the S value being calculated from the formula $$\mathrm{S}\mathrm{=}\left({\mathrm{m}}_{\mathrm{A}}\mathrm{/}{\mathrm{\Delta p}}_{\mathrm{7.8}}\right)\mathrm{/}\mathrm{dpf}\left[\mathrm{10}\mathrm{m}\mathrm{/}\mathrm{daPa}\right]$$

    

    
    in which m_A [g] is the fiber mass or filament mass, Δp [daPa] is the resistance to the passage of air and dpf (dtex) is the filament titer and, for the resistance to the passage of air, the value, calculated for a filter diameter of 7.8 mm, is used, and the hardness of the cigarette filter exceeds 90 filtrona hardness.
19. The tobacco smoke filter of claim 18, characterized in that the fiber mass or filament mass does not exceed 10 mg/mm of filter length and/or the residual crimping of the filter material does not exceed the value of 1.45, formula (III) applying here: $${\mathrm{I}}_{\mathrm{R}}\mathrm{=}\mathrm{10}\mathrm{,}\mathrm{000}\mathrm{\times }{\mathrm{m}}_{\mathrm{A}}\mathrm{/}\left(\mathrm{G}\mathrm{\times }\mathrm{I}\right)$$

    

    
    in which m_A [g] is the fiber mass or filament mass, G [g/10exp 4 m] is the total titer and I [mm] is the filter length.
20. The tobacco smoke filter of claim 19, characterized in that the residual crimping is between 1.05 and 1.4, in particular, between 1.1 and 1.3.
21. The tobacco smoke filter of at least one of claims 18 to 20, characterized in that the fiber mass (or filament mass) - resistance to the passage of air - ratio S, related to the filament titer, does not exceed a value of 2, in particular, has a value between 0.8 and 1.3.
22. The tobacco smoke filter of one of claims 18 to 21, characterized in that the fiber mass or filament mass is at least 4 mg/mm of filter length, in particular, between 5 and 8 mg/mm of filter length.
23. The tobacco smoke filter of at least one of claims 18 to 22, characterized in that the filtrona hardness is between 90 and 95, in particular, between 91 and 93.
24. The tobacco smoke filter of at least one of the preceding claims, characterized in that it contains a photoreactive additive, in particular, in the form of finely divided titanium oxide of the anatase type having an average particle size of less than 2 µm.