EP1221869B1 - High performance cigarette filter - Google Patents

Abstract

The invention relates to a high performance cigarette filter on the basis of cellulose ester fibers or filaments which can be mechanically disintegrated. The inventive high-performance cigarette filter is characterized in that a) the fiber weight (or filament weight)/draw resistance ratio S based on the filament titer is greater than approximately 0.7, the S value being calculated according to the formula S=(mA/DeltaP7.8/dpf[10 m/daPA], wherein mA refers to the fiber weight, DeltaP refers to the draw resistance and dpf represents the filament titer and for the draw resistance the value calculated for a diameter of 7.8 mm is inserted, b) the residual crimping value of the filter material does not exceed the value 1.45, c) the fiber weight amounts to maximally 10 mg/mm of the filter length, and d) the hardness of the cigarette filter is higher than approximately 90% filtrona hardness. The inventive filter is characterized by an improved disintegratability under environmental conditions vis-à-vis comparable products.

Description

The present invention relates to a high performance mechanical cigarette filter Disintegration based on fibers or filaments of cellulose esters.

The majority of the cigarette filters used today are made from filter tow, consisting of endless, cellulose-2,5-acetate filaments crimped in the stuffer box manufactured. A solution of approx. 30% cellulose-2,5-acetate is used to produce filter tow pressed in acetone through spinnerets, the acetone in a spinning shaft evaporated by blowing with heated air, a variety of filaments (3,000 up to 35,000) combined into a band and then crimped in the compression chamber. The product is then dried, filled into storage containers and ultimately pressed into bales weighing 300 to 600 kg. The total amount of filter tow, which is manufactured worldwide according to this process, is approx. 500,000 tons per year, which underlines the economic importance of the process. After transporting the filter tow bales to the filter or cigarette manufacturer the filter tow is removed from the bale and placed on a filter rod machine, such as for example described in US-A-5,460,590, processed into filter rods. there the filter is stretched in a stretching device, with a for gluing the Filaments serving additives and then after formation of a three-dimensional Fuse inserted into the format part with the help of an inlet funnel, there axially compressed, covered with paper and cut to the final length of the filter rods.

The additive applied to bond the filaments is generally a high-boiling solvent for cellulose acetate, such as glycerol triacetate (triacetin), which briefly dissolves the surface of the filaments after its application. Wherever two filaments accidentally touch each other, there is a fixed bond point some time later, since the excess additive migrates into the fiber surface, causing the previously liquid drop of solution, made of cellulose-2,5-acetate in the additive, to solidify. After a storage period of less than one hour, due to the aforementioned migration of the hardening agent, mechanically strong, three-dimensionally cross-linked filter rods (hereinafter referred to as "spatial filters") with a low packing density (nowadays 80-120 mg / cm ³ ) are obtained can be processed at high speeds on modern cigarette machines due to their hardness.

The advantages of the overall process are the high efficiency of filter tow production, the low transport costs from the filter tow manufacturer to the end customer and especially the high productivity in filter manufacturing, which is not is insignificantly determined by the length of the tapes in the bales. The processing by Filter Tow is used on commercially available filter rod machines such as for example the KDF 3 / AF 3 from the firm Körber AG, Hamburg. there production speeds of currently 600 m / min are state of the art. The Productivity of filter production can be achieved using DE-A-43 40 029 described double strand technology and when using the in DE-A-43 20 303 Twin Tow technology shown can be significantly increased. Another The advantage of conventional filter production is that you can Changing the speed ratio between the preparation and format part the filter properties with regard to pressure drop and thus the filtration performance can vary within wide limits while maintaining the filter tow specification. About that In addition, one can by varying the filament or total titer almost any variety of filters of different filtration performance the procedure described.

Cellulose 2,5-acetate is widely used today for the production of room filters. It owns with regard to the discussion regarding smoking and health Proven properties to be highlighted regarding specific retention phenomena. A filter made of cellulose acetate filters harmful nitrosamines and phenols far more efficiently than condensate and nicotine. In addition, the Smoky taste of the tobacco blend common today, such as "American Blend "," German Blend "and" Virginia "in combination with a spatial filter Cellulose acetate judged to be the most pleasant by the smoker. Another not The advantage of a spatial filter made of cellulose-2,5-acetate is to be underestimated in the optical Homogeneity of the cut surfaces of the filters is justified.

dpf Filamenttiter [dtex],

D Filterdurchmesser [mm],

ℓ Filterlänge [mm] und

ΔP Zugwiderstand [daPA].

All other possible polymers with which spatial filters could be produced using comparable processes have not been able to assert themselves on the market due to the negative influence on the taste of the smoke, lack of specific retention, problems with the hardening and cutting problems of the filters on the filter rod machine, but also on the cigarette machine. The consistently negative assessment of the smoke taste and the lack of specific retention when using other polymers for the production of spatial filters suggests that the advantages of today's acetate filter are not causally linked to the physical filter design, but to the adsorbing properties of the polymer cellulose-2,5 -acetate, which should also have a positive effect on area filters. However, regardless of their undeniable market dominance, room filters made of cellulose-2,5-acetate have some serious disadvantages: draw resistance and filtration performance are clearly defined for room filters due to structural physical requirements. The particle filtration or condensate retention "R _k " of a conventional spatial filter is a function of filament titer (fiber fineness), filter diameter, draw resistance and filter length. The following applies: R k = f (dpf, D, ℓ, ΔP) in which mean:

dpf filament titer [dtex],

D filter diameter [mm],

ℓ filter length [mm] and

ΔP tensile resistance [daPA].

There has been no shortage of attempts to establish the connection between these quantities present empirically determined equations. Examples of this are in the following Find publications: "Design of Cigarettes", C.L. Brown, Hoechst - Celanese Corporation, 3rd edition, 1990 and Cable ©: Capability Line Expert Copyright © 1994 by Rhodia Acetow AG, D - 79123 Freiburg.

The following empirically determined relationship is used in the current filter calculation program "Cable ©": R k = 100 * (1- D k ) where: D _k = permeability of the filter for condensate,
where: D k = exp (L * A + B) A = K1 - K2 * dpf L = 21 - ℓ and B = - (K3 * D 4 * ΔP + K4 / dpf + K5) K1 to K5 are constants which are determined empirically in accordance with the tobacco mixture used and the respective retention determination method. In other words: for a given filter length and a defined diameter, the filter performance of a cigarette filter is clearly determined by the tensile resistance of the filter and the filament titer of the filter tow specification used.

There has been no lack of attempts to increase the filtration performance of spatial filters while maintaining the specifications such as length, diameter, tensile resistance and filament titer. Such a high-performance filter is described, for example, in DE-A-26 58 479, in which case the filtration capacity can be increased by adding retention-increasing, finely dispersed metal oxides. The draw resistance of a room filter ΔP is also clearly defined. It depends on the diameter D of the filter, its length ℓ, the filament titer dpf, the total titer G [g / 10exp4 * m] and the fiber weight mA [g] ΔP = f (D, ℓ, dpf, G, m A )

For a given filter rod with a tensile resistance ΔP, a diameter D and A length ℓ is the fiber weight when using a defined filter tow specification clearly defined. The relationship between fiber weight and Draw resistance is because of the variety of filter tow specifications available, the filter rod dimensions, the realizable different residual ripples not to be presented in a closed mathematical equation. The However, the above Cable® allows residual ripple for any filter tow specification and filter rod dimension add the fiber weight for a given draw resistance to calculate.

The fiber weight mA of a filter is defined with the residual crimp and the total titer by the following equation: I R = 10,000 * m A / (G * ℓ)

The residual crimp is understood as the ratio of the length of the crimped filaments to the filter length. The residual ripple is a characteristic feature for a given cigarette filter. On the basis of the residual crimp values which are possible with means of the prior art and the filament titer for spatial filters made of cellulose esters which are common today, the total amount of spatial filters can be characterized by a ratio of fiber weight to tensile resistance based on the filament titer. It applies to spatial filters that the fiber weight / tensile resistance ratio S related to the filament titer is clearly defined and this value never exceeds the amount 0.7 and thus represents a characteristic variable. This relationship can be expressed for room filters made of cellulose ester by: S = (m A / ΔP 7.8 ) / dpf <0.7 [10 m / daPA] whereby the value converted to a diameter of 7.8 mm must always be used for the tensile resistance. The following equation applies to the conversion: .DELTA.P 7.8 = ΔP x * (D x / 7.8) 5.8 [DaPA] where the index X denotes the diameter of the actual sample.

Despite the resulting enormous variety of possible spatial filters exist due to the relationships mentioned (equation 2) restrictions regarding the achievable condensate retention.

It is technically completely problem-free, with the spectrum of the filter tow common today Specifications to manufacture filters to match the full-flavor cigarette segment as well to cover how the segment of medium and light cigarettes. Problematic it will be when filtering performance, like for the construction of ultra-light cigarettes required of significantly more than 50% with a common filter diameter of 7.80 mm and a filter length of 21 to 25 mm is required. Since the With a room filter, smoke flows parallel to the fiber direction, this is only through one to achieve a significant reduction in the filament titer, while maintaining the same of the total titer would result in a significant increase in train resistance. total denier and filament titre must be reduced equally, with the result that the hardness of the filter, especially during smoking, is drastic is reduced. This phenomenon is called "hot collapse" by a person skilled in the art and is considered completely undesirable.

Specific retention benefits caused by additives can only be achieved with realize comparatively high base retention. For example, WO describes 97/16986 anti-mutagenic additives that only work in conjunction with one high minimum nicotine retention. This requirement is clearly limited the spectrum of the filter tow specifications applicable in WO 97/16986 (see examples in Table II, page 13).

Another undeniable disadvantage of room filters made from cellulose acetate is their poor mechanical disintegration in the environment. This bad one Disintegration delays the breakdown of cigarette filters that get into the environment sustainable. It has been demonstrated that the breakdown of cellulose acetate fibers can be accelerated effectively by various measures. All however, these measures also work towards improving biological Degradability of the polymer cellulose acetate, but not towards easier The filters can be disintegrated. The effect of z. B. in DE-C-43 22 966 and DE-C-43 22 965 measures is essentially due to the three-dimensional Crosslinking of the filaments in a spatial filter is limited. The to dismantle the Microorganisms necessary for filter material therefore have one in the field little access to the filaments and thus to biodegradation of the polymer. The improved biodegradability of the polymer is therefore overdetermined or dominated by the poor mechanical disintegration of the room filter.

Since the above-mentioned stuffer box crimp is a three-dimensional one Ripple occurs in the fuse formed during filter manufacture without hardening additive, but also, as suggested in DE-C-43 22 966, when used water-soluble adhesive, a three-dimensional cross-linking of the filaments in the manufacture filters that are so significant that the mechanical disintegration of the filters in the environment in these cases, too. Similar restrictions apply to the photochemical degradation of filaments. The in EP-A-0 716 117 and EP-B-0 732 432 acceleration is limited by those described constructive disadvantages of a room filter.

In EP-A-0 880 907 it was therefore proposed to use cross-hooking of filter tow specifications with extremely low residual ripple (see page 5, equation 8) in the finished filter as far as possible. Ultimately, this will be achieved by drastically increasing the total titer and thus the filter weights. This naturally results in an increase in the train resistance. For compensation these high tensile resistances must therefore be raised accordingly be (see Example II).

EP-A-0 880 907 describes partial cutting as further measures the filter after its manufacture and the use of water-soluble glue. For the sake of completeness it should be mentioned that that described in EP-A-0 880 907 disintegrable cigarette filter the criteria of the spatial filter with respect to the Filament titer related weight / tension resistance ratio S <0.7 fulfilled (example II: S = 0.31 m / daPA).

A completely different process for producing aerosol filters uses a flat structure as the starting material, such as paper, spunbonded nonwovens, textile fabrics or non-wovens (in the following, such filters are referred to as "surface filters"). These filters circumvent the filter performance and disintegrability limitations mentioned above. A flat structure is produced by the manufacturer of the filter material, rolled up on bobbins and then shipped to the processor. The filter or cigarette manufacturer unrolls the material from the bobbin, forms it into a rod-shaped product, then compresses it axially in the format section of the filter rod machine, wraps it with paper and cuts it to the final length of the filter rods. In addition to this, the flat structure is usually, but not necessarily, crimped parallel to the running direction by a creping device before being formed into a rod. On the one hand this results in a lowering of the material density and on the other hand an influence on the pressure drop (tensile resistance) of the filter. Nevertheless, the packing density of the area filter known today with a fiber weight of 120 to 300 mg / cm ^{3 is} significantly higher than that of the known spatial filter made of cellulose acetate. Cross-linking of the nonwoven layers generally does not take place and is deliberately not sought.

The best-known area filter consists of paper and is, for example, from the company Filtrona, Hamburg, marketed under the trade name Myria Filter. In the WO 95/14398 becomes a filter made of paper made of artificial, highly fibrillating cellulose fibers Lyocell fiber, in a mixture with cellulose fibers or also acetate fibers described. Furthermore, WO 95/35043 relates to a cigarette filter made from a needled water Tissue, which in turn contains the Lyocell fiber as a component there.

In addition to the methods mentioned in the applications mentioned, you can of course all known processes related to the formation of fabrics with the most interesting because of its fiber diameter after fibrillation Lyocell fiber can be used to manufacture surface filters.

All of these filters are considered to be readily biodegradable because they are easily disintegrable due to the lack of cross-linking of the surface layers and the low water resistance of products made in a paper process. After rewinding of the cigarette filter to a sheet under environmental influences offers a such a fabric also, in contrast to a difficult to disintegrate Space filter, a comparatively much larger surface for biological Degradation of suitable microorganisms. Another major advantage of the area filter consists in a significantly higher nicotine and condensate retention compared to Room filters corresponding draw resistance. This higher filtration rate is on attributed to the physical construction of the surface filter and therefore not depending on the filter material used.

Nevertheless, when using area filters, where the filter material is not or only partially consists of cellulose acetate, always the negative taste Influencing the smoke by e.g. B. consumer cellulosic fibers judged negatively. In addition, these mainly consist of cellulosic fibers Do not use the high selective filters that are typical of cellulose acetate room filters Retentions to phenols and nitrosamines.

There has therefore been no shortage of attempts in the past to use surface filters on the Propose base of cellulose acetate. DE-A-27 44 796 describes the use of so-called cellulose acetate fibrets in combination with cellulose acetate or natural or synthetic fibers for the production of surface filters. For example, US-A-3 509 009 describes the use of the melt blown technique for the production of nonwovens for use in cigarette filters.

DE-C-196 09 143 claims a melt blown fleece and the like. a. for production of Cigarette filters based on a thermoplastic cellulose acetate. All out the materials described cigarette filters have the advantage that the Filtration performance (measured as nicotine or tar retention) compared to these filters comparable room filters made of cellulose acetate in the tensile resistance is significantly higher. It is also known that pure cellulose acetate for processing in processes with thermal deformation of the polymer is not suitable. The problems that arise are described in detail in DE-C-196 09 143.

Another disadvantage is that due to the higher density mentioned, the filter, the The amount of material used is comparatively so high that even when using a cheap raw material, like paper based on paper pulp, the price per filter is not differs significantly from that of a room filter made of cellulose acetate. Essential However, the filters become more expensive if you make flat structures from spun endless Fibers used in manufacturing. In these cases there is a spinning process at the beginning to make a crimped tow, which is then cut into a fiber which in turn then becomes an areal structure in an additional work step is processed as the raw material for the filter manufacturer. Examples of one such procedures are in the already mentioned WO 95/14398 or DE-A-27 44 796.

Given the disadvantages outlined above, it is understandable that the technology of the area filter, produced by the multi-stage process (spinning, Cutting, fleece production), when processing into mass articles (full flavor or light segment) has never prevailed.

A significantly different process for the production of surface filters from cellulose acetate describes DE-A-1 930 435. A conventional filter tow is produced from non-thermoplasticized cellulose acetate fibers, drawn from a bale, in spread out a conventional preparation part, stretched and with a conventional plasticizer Mistake. Deviating from the usual processing method for The prepared filter tow web is then manufactured in a room filter Heater heated and then with the help of profiled, heated Thermoplastic cross-linked rollers under pressure. The two-dimensional manufactured in this way solidified fabrics are then combined, compressed axially, with paper wrapped and cut. This creates, as described in US-A-4,007,745, a surface filter made of endless cellulose ester filaments. An advantage of the process is that for the first time, from the product properties of the filters, the advantages of the surface filter in terms of nicotine and condensate retention the advantages of the cellulose acetate polymer in terms of specific retention and taste combined. Also the one-step, inexpensive conversion of filters Tow to an area filter advantageous. However, the filter is characterized by a large number of triangular smoke channels which are formed from a fleece, which has a large number of rectangular depressions. Another The disadvantage of this filter construction is that the triangular channels in particular become clearly visible when smoking, which is a visual disadvantage of the manufactured Makes products noticeable.

The method described in DE-A-1 930 435 and the corresponding cigarette filter US-A-4,007,745, however, have some other significant disadvantages: Caused by the thermoplastic fusion of the filaments large, completely fused areas of low porosity (see Fig. 2 to 6), which are ineffective for the filtration of the smoke. As a result, you need these Filter a material input that is significantly higher than today's room filter. As an example, filters are described in US Pat. No. 4,007,745, their use of materials the amount currently used exceeds two to two and a half times (see example 4 to 7).

Furthermore, the ripple in the non-consolidated areas is three-dimensional oriented (see DE-A-1 930 435, Fig. 6), with the result that the adjacent surface layers in the case of transverse axial compression to the filter rod, again in part three-dimensionally network. This is reinforced by the fact that the short thermal treatment of the filter tow web before thermoplastic crosslinking of the fleece, the plasticizer previously applied for plasticization not yet in the Fiber has migrated and therefore, according to the hardening of room filters Cellulose acetate, contributes to the bonding of neighboring layers of fleece. It is too know that it is the plasticizing described in DE-A-1 930 435 of the cellulose acetate used products to the same chemical substances acts as it functions in the curing of room filters made of cellulose acetate can be used as a solvent.

The last two disadvantages mentioned prevent the surface filter from rolling up again to a nonwoven web. The principles responsible for this correspond to those the spatial filter discussed above.

Another disadvantage of the teaching of DE-A-1 930 435 is that the Filter Tow web at the time of web formation, as already mentioned, with hardening agent is wetted, which makes the surface very sticky. This leads to sticking on the calender roll and therefore carries out the process, in particular at processing speeds of> 100 m / min, extremely difficult.

The invention is therefore based on the object, surface filter based on endless To provide cellulose ester fibers which have the disadvantages of the prior art explained above the art, especially the filter described in US-A-4,007,745 exhibit. These should be sufficient even without three-dimensional networking Have hardness, their mechanical disintegration ability being that of surface filters should correspond to which were made from nonwovens with short cut fibers. The Filtrona hardness should be based on market requirements. Further the surface filters are the advantageous known from the prior art or in Maintain improved properties in individual cases.

a) das auf den Filamenttiter bezogene Fasergewicht/Zugwiderstandsverhältnis S größer ist als etwa 0,7, wobei der S-Wert nach der Formel: S = (mA / ΔP7.8) / dpf   [10 m/daPA] berechnet wird, worin bedeuten
mA das Fasergewicht [g], ΔP den Zugwiderstand [daPA] und dpf den Filamenttiter [dtex] und für den Zugwiderstand der auf einen Durchmesser von 7,8 mm umgerechnete Wert eingesetzt wird,

b) die Restkräuselung IR des Filtermaterials den Wert von 1,45 nicht übersteigt, wobei sich IR ergibt aus der Formel IR = 10.000 * mA / (G * 1), wobei gilt für mA = Fasergewicht [g], G = Gesamttiter [g/10 exp 4 * m] sowie 1 = Filterlänge [mm],

c) das Fasergewicht maximal 10 mg/mm Filterlänge beträgt und

d) die Härte des Zigarettenfilters etwa 90% Filtronahärte überschreitet.

According to the invention, the above object is achieved by a high-performance cigarette filter with mechanical disintegration on the basis of fibers or filaments of cellulose esters, in particular cellulose acetate, characterized in that

a) the fiber weight / tensile resistance ratio S, based on the filament titer, is greater than about 0.7, the S value according to the formula: S = (m A / ΔP 7.8 ) / dpf [10 m / daPA] is calculated in which mean
mA the fiber weight [g], ΔP the tensile resistance [daPA] and dpf the filament titer [dtex] and for the tensile resistance the value converted to a diameter of 7.8 mm is used,

b) the residual ripple IR of the filter material does not exceed the value of 1.45, IR resulting from the formula IR = 10,000 * mA / (G * 1), where mA = fiber weight [g], G = total titer [g / 10 exp 4 * m] and 1 = filter length [mm],

c) the fiber weight is a maximum of 10 mg / mm filter length and

d) the hardness of the cigarette filter exceeds about 90% Filtrona hardness.

To produce a filter according to the invention, either a thermoplastic Cellulose ester, fiber or filament material or in the case of a non-thermoplastic Cellulose ester uses a water-soluble adhesive. Will follow spoken of fiber material, then the corresponding design should also apply to filament materials, if appropriate. (Regarding the thermoplastic Properties of cellulose ester derivatives should be based on those shown in DE-A-196 09 143 Discussion regarding internal and external plasticizers (p. 1, lines 65 ff) directed. The findings made there are for understanding the following Execution of fundamental importance. For the definition of thermoplastics also on "Römpps Chemielexikon", 8th ed., Vol. 6, Franckh'sche Verlagbuchhandlung, Stuttgart 1988, p. 4229 ", for the first case of a thermoplastic A distinction can be made between two cases of cellulose ester fiber material. In the first Case is the fiber material from an inherently thermoplastic cellulose ester, such as. Cellulose acetobutyrate. In this case, the filter Tow can be processed into filters according to the invention without further measures. in the In the case of a non-thermoplastic starting polymer, e.g. Cellulose-2,5-acetate, it must be thermoplasticised by adding a suitable plasticizer. In this case the plasticizer must be homogeneously distributed in the fibers. The homogeneous Distribution of the plasticizer in the fibers can be done by different Demonstrate methods. These are, for example: recording the evaporation kinetics the plasticizer. To do this, a filter plug can be placed in an inert gas stream be heated and the evaporation rate via combustion in a commercially available Flame Ionization Detector (FID) can be detected. The evaporation rate one in the

Fiber evenly applied plasticizer differs sustainably from that a superficially applied plasticizer. Because the evaporation is diffusion controlled the evaporation kinetics with a uniform distribution is significant slower than with superficial application. Another possibility is the Show evaporation kinetics using differential thermogravimetry. Third, can the even distribution by short-term extraction methods in for the polymer suitable solvents with subsequent quantitative analysis of the plasticizer be determined. This method provides one for a homogeneously distributed plasticizer significantly lower analysis value than for the superficially applied plasticizer with the same percentage salary. Another superficial and It is possible to differentiate qualitatively evenly distributed plasticizers using NIR reflection. This method delivers for homogeneously distributed Plasticizer has a significantly lower analysis value than for the only superficial applied plasticizer at the same percentage.

To produce the filter according to the invention, a filter tow is pulled off the bale, pneumatically spread out and according to the usual procedure for room filters stretched. Before the actual filter production step, a non-woven fleece is used as an intermediate with the lowest possible strength in the direction of both surface axes generated. Surprisingly, it has been shown that this is particularly successful when the plasticizer necessary for thermoplasticizing the polymer evenly in the fiber is distributed.

In the context of the present invention, the ratio is based on the filament titer of fiber weight / tensile resistance S according to the above formula than about 0.7. If this value is fallen below, this leads to retention values, as they are common with conventional cellulose acetate filters. This is preferably maximum fiber weight / tensile strength ratio S related to the filament titer about 2, and is particularly in the range of about 0.8 to 1.3. Will be the preferred one Value of about 2 for the ratio S exceeded, then this product does not meet more the desired profitability requirements.

With regard to the other underlying parameters, the following preferably apply conditions:

The residual crimp _IR of the filter material is less than 1.45. The residual crimp is preferably between approximately 1.05 and 1.4, in particular between approximately 1.1 and 1.3.

The fiber weight can be a maximum of 10 mg / mm within the framework of the teaching according to the invention Filter length, in particular a maximum of 9.0 mg / mm filter length, and preferably at least about 4 mg / mm filter length. The preferred range is between about 5 to 8 mg / mm filter length. If the maximum value of 10 mg / mm filter length is exceeded, then such a product is not sufficiently economical. Preferably a minimum value of about 5 mg / mm filter length is observed. This value falls below, then the desired hardness of the No longer comply with cigarette filters of at least 90%. The minimum limit of Filtrona hardness of around 90% is based on market requirements. The Filtrona hardness the cigarette filter according to the invention can preferably be approximately 90 to 95%, in particular about 91 to 93%. (Determination of the Filtrona hardness: A cylindrical rod of 12 mm diameter presses with its flat Vertical face with a load of 300 g on a horizontally positioned filter rod. The ratio of the compressed diameter to the previously by the The first touch of the determined output diameter gives the percentage of the Filtrona hardness). It proves to be of particular advantage if a high performance cigarette filter according to the invention after the CBDTF test after 10 weeks of testing a weight loss of at least about 40% in particular at least about 50% by weight.

The tensile resistance of the filters according to the invention is preferably in a range between 1 and 12 daPA / mm filter length. The filament titer of the filters used Tow qualities vary between 1 and 20 dtex.

The disintegrability of the cigarette filter according to the invention is raised by a low residual crimping I _R. This low residual curl reduces the cross-hooking of the filaments within and between the levels of the nonwoven webs. As stated above, the residual ripple of the filter according to the invention is less than 1.45.

To further improve the mechanical disintegration of the Filters, it is recommended to use a multi-width fiber strip to produce the teaching of DE 43 40 029. According to a further embodiment the cigarette filter can be made from a fiber strip, which before entry was cut into several strips in the strand part of the filter rod machine.

The endless thermoplastic cellulose ester fibers of the invention can include cellulose acetate, in particular cellulose-2,5-acetate, cellulose butyrate, cellulose acetobutyrate, Cellulose acetopropionate and / or cellulose propionate. advantageously, have the endless thermoplastic fibers of cellulose acetate according to the invention a degree of substitution of about 1.5 to 3.0, preferably about 2.2 to 2.6.

The used for thermoplasticizing the cellulose esters used and in the Fibers evenly distributed plasticizers can be, for example, from the following Groups can be selected: glycerol esters (especially glycerol triacetate), ethylene and Propylene carbonate, citric acid esters (especially acetyl, triethyl citrate), glycol esters (especially triethylene glycol diacetate (TEGDA) or diethylene glycol dibenzoate), Carbowax® (especially polyethylene glycols with a molecular weight of 200 to 14,000, such as manufactured by UCC, USA), sulfolane (tetrahydrothiophene-1,1-dioxide), Fatty acid esters, phosphoric acid esters (especially trioctyl, triphenyl or trimethyl phosphate), esters of phthalic acid (especially dimethyl, diethyl, Dibutyl and / or diisodecyl phthalate) and mixtures of any composition from one or more of these substances.

The amount of plasticizing plasticizer and / or water-soluble to be used Adhesive is straightforward to the person skilled in this technical field common. Generally there is a content of plasticizer and / or adhesive from about 1 to about 40% by weight, in special cases the content of Plasticizers, however, easily exceed this range without the Teaching of the invention is concerned.

As a water-soluble adhesive, preferably on the surface of the fibers can be the usual ones in the manufacture of spatial filters from cellulose acetate high-boiling solvents used, such as polyalkylene oxides (such as polyethylene glycols, Polypropylene glycols or copolymers of polyethylene and polypropylene oxide and their derivatives), water-soluble esters or ethers (also cellulose esters or ether), starch, starch derivatives, p-polyvinyl alcohols (partially or completely hydrolyzed, as well as derivatives thereof), polyvinyl ethers (and their derivatives), p-polyvinyl acetates and / or polysaccharides, water-soluble polyamides and polyacrylates used, i.e. be applied to the fiber web.

In a further preferred embodiment of the invention, the cellulose ester fibers contain or filament additives in the form of photo-reactive additives, the biological Degradability-promoting additives, additives with selective retention effect and / or colored pigments. Preferred is a photo-reactive additive a finely dispersed anatase-type titanium dioxide with an average particle size of less than 2 µm used. As additives that promote biodegradability to be mentioned in particular: nitrogenous substances, their natural or microbial Release degradation products of basic amines (e.g. urea and its derivatives; Oligopeptides and proteins such as beta-lactoglobulin; condensates from carbonyls and amines, such as hexamethylenetetramine; as well as nitrogenous organic heterocycles, especially carbazoles).

Preferred additives with a selective retention effect are filtration aids such as these are mentioned for example in WO 97/16986. Organic are preferred Acids or acidic carboxylic acid esters, polyphenols, or porphyrin derivatives are used.

The high-performance cigarette filter according to the invention can be taken by suitable measures thus with regard to the biological and photochemical degradability to be improved to an extent as is the case with prior art room filters Technology is only possible to a limited extent.

The advantages associated with the invention are therefore numerous. In particular, the easy disintegration of the filter according to the invention under environmental influences of great advantage. This can in terms of biological and photochemical degradability compared to a known spatial filter can be significantly improved. moreover it has a higher level than spatial filters, for example made of cellulose acetate Retention with the same tensile resistance, at the same time the ones placed on the filter Requirements, in particular of the cigarette manufacturer and the end user, in to a high degree. By mixing different output tows any filament size (filament titer) it is also possible to choose an optimum to adjust area volume and filtration capacity accordingly. This way of working also enables the filter to be optimized according to its Filtrona hardness. Furthermore, due to the plasticizer present, such as triacetin, a positive taste influences occur, but at the same time an essential one less amount of plasticizer passes directly into the smoke. As a result in the high-performance cigarette filter according to the invention, significantly lower condensate values detected.

The invention is illustrated below using examples which illustrate the invention Teaching should not limit, described in detail. The specialist are in Within the scope of the disclosure according to the invention, further exemplary embodiments are evident.

Examples: Comparative Example 1:

As a comparison example 1, which represents a cigarette filter (spatial filter) that is common today, A cigarette filter was made from a filter tow of the specification 3.0 Y 35. This filter consists of individual filaments with a filament titer of 3.33 dtex and a total titer of 38,889 dtex, where Y describes the cross section of the filament. The filters have a length of 21 mm and a diameter of 7.80 mm. The triacetine content is 7% (= 8.5 mg). The draw resistance is 60 daPA at an acetate weight of 107 mg. The filters were covered with a non-porous Filter wrapping paper from Glatz (D-67468 Neidenfels) with the designation F 796-28. The Filtrona hardness of the filter rods is 92.2%. The filter therefore has a weight / tensile resistance ratio of S standardized to the filament titer = 0.54 (10 m / daPA). These filters were designed according to the one described below a test method developed by a CORESTA working group (CBDTF test) regarding examined their disintegration. The results are summarized in Table 1.

The test material (10 filter plugs, freed from paper) is irradiated with a xenon burner at wavelengths greater than 290 nm. The radiation intensity is determined at 340 nm and set to 0.35 Wm ^-2 nm ^-1 . The temperature, measured by a white standard, is 55 ° C. The samples are irrigated twice a day with deionized water. Once a day, the samples are mechanically loaded by shaking with four steel balls (M = 16g, D = 1.2 cm) in a steel beaker. After conditioning of the samples, the weight and optionally the volume are determined weekly. To determine the condensate retention of the filters, the 21 mm long filters were coupled to an "American blend" tobacco rod and according to CORESTA recommended No. 22 and 23 smoked. The Cambridge filter and the filters separated from the tobacco stub are extracted in methanol and, after appropriate dilution, the extinction of the solutions at a wavelength of 310 nm is determined by UV spectroscopy. The retention is then calculated using the following equation: R k = E filter / (E filter + E Cambridge filter ).

In comparative example 1, the condensate retention was determined to be 37.5%.

Comparative Example 2:

A filter tow of specification 3.0 Y 55 (filament titer: 3.33 dtex; total titer: 61.111 dtex) was on a standard two-stage drafting system KDF 2 from the company Hauni, Hamburg, processed and sprayed with 8% triacetin. After leaving the Deflection roller is the filter tow web with a minimum width of 250 mm in one Pair of heated calender rolls inserted and with an effective line print of 40 kg / cm calendered. The profiled calender rolls have a diameter of 230 mm and a grooved width of 350 mm and have 10 profile grooves per cm on. They are heated to a temperature of 205 ± 3 ° C with a silicone oil. The Grooved profile is trapezoidal with an upper width of 0.4 mm and a depth of 0.45 mm and an included angle of 35 °.

After leaving the calender roll, the fleece thus produced is introduced into an inlet nozzle folded in a strand and in a commercially available KDF2, from Körber, Hamburg, wrapped in paper at a line speed of 70 m / min and cut to a filter rod length of 126 mm. The diameter of the filter rods was set to 7.8 mm. The Filtrona hardness of the filter rods is 89.5%. Filter plugs with a length of 21 mm are then cut from these rods, which then, as shown in Comparative Example 1, with regard to their disintegrability are examined (the results are summarized in Table 1). The train resistance this filter rod is 51 daPA with an acetate weight of 141 mg. The fiber weight / tensile resistance ratio based on the filament titer is thus S = 0.83 [10 m / daPA]. The condensate retention, determined as in Comparative Comparative Example 1 described was 42.3%.

Evidence of the non-homogeneous distribution of the sprayed triacetin is like follows as follows: A filter plug produced three months before the examination date the length 21 mm is in a V2A steel tube with an inner diameter of 7.5 mm introduced. The inside diameter of the steel pipe is determined on both sides by a suitable one technical means tapered to a diameter of 0.3 mm. On the entry side Nitrogen gas flowed in at a flow rate of 30 ml per minute and on the outlet side with a commercially available flame ionization detector (FID) connected. The sample tube is placed in a heating furnace with a heating rate of 75 ° C / min heated to an oven temperature of 150 ° C. The recorded FID signal reaches its maximum intensity after two minutes and the baseline after about 6 minutes.

Example:

In a double-walled universal mixer with a total volume of 615 1 volume and cooling / heating device, 300 kg of cellulose acetate flakes were filled. The Mixing tool 1 is in one piece with three blades all around the floor and vertically plugged onto the drive shaft. Horizontal to the drive shaft is one-piece, four-winged Chopper tool 2 attached, which agglomeration during the Plasticizer addition and diffusion prevented and with 21 m / sec (2890 rpm) peripheral speed is operated.

The mixer 1 was operated at a peripheral speed of 6.5 m / sec set. 65 kg of triacetin were added uniformly over 10 minutes. To this The chopper tool 2 is switched on at the time. It continued to be intimate Mixing intensely mixed for 12 min. In the next 20 minutes, up to one Material temperature of 76 ° C heated. This temperature was maintained for 5 minutes. The mixture was then continuously cooled to 20 ° C. for 30 minutes. The total exposure time of the triacetin on the flakes was 67 min. Then the Mixer drained quickly within three minutes. This according to this procedure The product obtained can be poured and stored very well. The thermoplasticized cellulose acetate granulate becomes a filter using the usual dry spinning process Tow of the specification 3.0 Y 55 [filament titer 3.33 dtex; Total titre 61,111 dtex] processed.

This filter tow was on a standard two-stage drafting system KDF 2 Hauni company, Hamburg, processed. In contrast to comparative example 2 no additional plasticizer applied after stretching. After leaving The deflection roller is the filter tow web with a minimum width of 250 mm in introduced and calendered a pair of heated calender rolls. The profiled Calender rolls have a diameter of 150 mm and a width of 550 mm and have 10 profile grooves per cm. They are brought to a temperature with a silicone oil heated from 180 ± 3 ° C. The groove profile is trapezoidal with an upper one 0.4 mm wide and 0.45 mm deep with an included angle of 35 °. After leaving the calender roll, the fleece produced in this way is introduced folded into an inlet nozzle in a rope shape, and in a commercially available KDF2, from Körber, Hamburg at a line speed of 120 m / min with paper wrapped and cut to a filter rod length of 126 mm. The diameter of the Filter rods were set to 7.8 mm. The Filtrona hardness of the filter rods is 91.4%.

Filter plugs with a length of 21 mm are then cut from these rods, which then, as shown in Comparative Example 1, with regard to their disintegrability are examined (the results are summarized in Table 1). The train resistance this filter rod is 51 daPA with a fiber input weight of 156 mg. The fiber weight / tensile resistance ratio based on the filament titer is thus S = 0.92 [10 m / daPA]. Condensate retention, determined as described in Comparative Comparative Example 1 was 44.1%.

The proof of the homogeneous distribution of the sprayed triacetin is as follows led: A filter plug of the three months before the examination date Length 21 mm is in a V2A steel tube with an inner diameter of 7.5 mm introduced. The inside diameter of the steel pipe is determined on both sides by a suitable one technical means tapered to a diameter of 0.3 mm. On the entry side Nitrogen gas flowed in at a flow rate of 30 ml per minute and on the outlet side with a commercially available flame ionization detector (FID) connected. The sample tube is placed in a heating furnace with a heating rate of 75 ° C / min heated to an oven temperature of 150 ° C. The recorded FID signal reaches its maximum intensity after four minutes at the earliest and the baseline after about 10 minutes.

Table 1 shows the results of the tests for disintegrating comparative examples 1, 2 and the example according to the invention. Test duration in test duration in weeks Comparative Example 1
Residual weight [%] Comparative Example 2
Residual weight [%] example
Residual weight [%] 1 93 95 87 2 92 94 85 3 92 94 82 4 91 94 75 5 88 93 69 6 86 93 62 7 81 92 47 8th 78 91 34 9 76 90 28 10 72 89 21

It can be seen from the above table values that the disintegration of an invention manufactured product with increasing test duration the values of the comparative examples is surprisingly clearly superior.

All measured data are summarized in Table 2. Dpf G IR draw resistance fiber weight diameter S hardness [Dtex] [DaPA] [Mg] [Mm] [10 m / daPA] [%] Comparative Example 1 3.33 38889 1.31 60 107 7.8 0.54 92.2 Comparative Example 2 3.33 61111 1.09 51 141 7.8 0.83 89.5 example 3.33 61111 1.22 51 156 7.8 0.92 91.4

Claims (18)

1. A high-performance cigarette filter with the ability to disintegrate mechanically based on fibres or filaments of cellulose esters, characterised in that

   a) the fibre weight (or filament weight), with respect to the filament titre, tensional resistance ratio S is larger than about 0.7, whereby the S value is calculated in accordance with the formula: S = (mA / ΔP7,8) / dpf [10 m/daPA] wherein m_A indicates the fibre weight (g), ΔP the tensional resistance (daPA) and dpf the filament titre (dtex) and for the tensional resistance the value calculated at a diameter of 7.8 mm is used,

   b) the residual crimp IR of the filter material does not exceed the value of 1.45, whereby I_R is produced by the formula IR = 10,000 *mA/(G*1), whereby m_A = fibre weight (g), G = overall titre (g/10⁴ * m) and 1 = filter length (mm),

   c) the fibre weight is at most 10 mg/mm filter length and

   d) the hardness of the cigarette filter exceeds about 90% Filtrona hardness.
2. A high performance cigarette filter as claimed in Claim 1, characterised in that the cellulose material is cellulose acetate.
3. A high performance cigarette filter as claimed in one of Claims 1 to 2, characterised in that the cellulose ester material is thermoplastic and the fibres or filaments, if a plasticizer is incorporated, contain it uniformly distributed.
4. A high performance cigarette filter as claimed in one of Claims 1 to 3, characterised in that a water soluble adhesive agent is present on the surface of the fibres or filaments.
5. A high performance cigarette filter as claimed in at least one of the preceding claims, characterised in that the residual crimp is between about 1.05 and 1.4, particularly between about 1.1 and 1.3.
6. A high performance cigarette filter as claimed in at least one of the preceding claims, characterised in that the cigarette filter has been produced from a multiple breadth fibre strip.
7. A high performance cigarette filter as claimed in at least one of the preceding claims, characterised in that the cigarette filter was produced from a fibre strip which was previously separated into a number of strips.
8. A high performance cigarette filter as claimed in at least one of the preceding claims, characterised in that the thermoplastic fibres or filaments contain cellulose acetate, particularly cellulose-2,5-acetate, cellulose butyrate, cellulose acetobutyrate, cellulose aceropropionate and/or cellulose propionate.
9. A high performance cigarette filter as claimed in at least one of the preceding claims, characterised in that, if a plasticizer is used, the plasticizer content is between about 1 and 40%.
10. A high performance cigarette filter as claimed in at least one of the preceding claims, characterised in that, if a plasticizer is used, it is triacetin, triethylene glycol diacetate and/or acetic acid diethyl ester.
11. A high performance cigarette filter as claimed in at least one of the preceding claims, characterised in that the thermoplastic fibres or filaments are based on cellulose acetate with a degree of substitution of about 1.5 to 3.0, particularly about 2.2 to 2.6.
12. A high performance cigarette filter as claimed in at least one of the preceding claims, characterised in that the water soluble adhesive agents are present in the form of polyethylene glycols, water soluble esters or ethers, starch and/or starch derivatives,-p-polyvinyl alcohols, p-polyvinyl acetates.
13. A high performance cigarette filter as claimed in Claim 1, characterised in that the fibre weight (or filament weight), with respect to the filament titre, tensional resistance ratio S is at most about 2 and is, in particular, in the range of about 0.8 to 1.3.
14. A high performance cigarette filter as claimed in at least one of the preceding claims, characterised in that the fibre weight (or filament weight) is at least about 4 mg/mm filter length, particularly about 5 to 8 mg/mm.
15. A high performance cigarette filter as claimed in at least one of the preceding claims, characterised in that the Filtrona hardness of the cigarette filter is about 90 to 95%, particularly about 91 to 93%.
16. A high performance cigarette filter as claimed in at least one of the preceding claims, characterised in that the cellulose ester fibres or filaments contain additives in the form of photoreactive additives, additives which promote biological decomposability, additives with selective retention action and/or coloured pigments.
17. A high performance cigarette filter as claimed in Claim 16, characterised in that a finely dispersed titanium dioxide of the Anatas type with a mean particle size of less than 2µm is used as the photoreactive additive.
18. A high performance cigarette filter as claimed in Claim 16, characterised in that organic acids or acidic carbonic acid esters, polyphenols and/or porphyrine derivatives are used as additives.