EP1221869A1

EP1221869A1 - High performance cigarette filter

Info

Publication number: EP1221869A1
Application number: EP00972837A
Authority: EP
Inventors: Eberhard Teufel; Günter Maurer; Emmerich Sackers
Original assignee: Rhodia Acetow GmbH
Current assignee: Cerdia Produktions GmbH
Priority date: 1999-10-22
Filing date: 2000-10-20
Publication date: 2002-07-17
Anticipated expiration: 2020-10-20
Also published as: SK285134B6; EA003238B1; CZ296610B6; PT1221869E; HUP0203081A2; PL202497B1; PL355636A1; HK1054491A1; JP2004536551A; KR100505177B1; ATE258017T1; DE50005096D1; DK1221869T3; SK5292002A3; AU764251B2; NZ518131A; EA200200482A1; BR0015000A; KR20020063564A; US6776168B1

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 / ΔP7.8 / dpf [10 m/daPA], wherein mA refers to the fiber weight, ΔP 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

A high performance cigarette filter

The present invention relates to a high-performance cigarette filter with mechanical disintegration on the basis of fibers or filaments of cellulose star.

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. To produce filter tow, a solution of approx. 30% cellulose-2,5-acetate in acetone is pressed through spinnerets, the acetone is evaporated in a spinning shaft by blowing with heated air, a large number of filaments (3,000 to 35,000) into a band summarized and then crimped in the stuffer box. The product is then dried, filled into storage containers and finally pressed into bales weighing 300 to 600 kg. The total amount of filter tow that is currently produced worldwide using this process is approximately 500,000 tons per year, which underlines the economic importance of the process. After the filter tow bales have been transported to the filter or cigarette manufacturer, the filter tow is removed from the bale and processed into filter rods on a filter rod machine, as described, for example, in US Pat. No. 5,460,590. The filter is stretched in a stretching device, provided with an additive used to glue the filaments, and then, after forming a three-dimensional fuse, is inserted into the format part with the help of an inlet funnel, compacted there axially, 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 enters the The fiber surface migrates, causing the previously liquid drop 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 lie in the high efficiency of the filter tow production, the low transport costs from the filter tow manufacturer to the end customer and in particular the high productivity in the filter production, which is not insignificantly determined by the length of the belts in the bales. Filter Tow is processed on commercially available filter rod machines, such as, for example, the KDF 3 / AF 3 from Körber AG, Hamburg. Production speeds of currently 600 m / min are state of the art. The productivity of filter production can be increased significantly when using the double-strand technology described in DE-A-43 40 029 and when using the twin-tow technology shown in DE-A-43 20 303. Another advantage of conventional filter production is that by changing the speed ratio between the preparation and format part, the filter properties with regard to pressure drop and thus the filtration performance can be varied within wide limits while maintaining the filter tow specification. In addition, by varying the filament or total titer, an almost arbitrarily large variety of filters with different filtration capacities can be produced according to the described method.

Cellulose 2,5-acetate is widely used today for the production of spatial filters. With regard to the discussion on smoking and health, it has demonstrably noteworthy properties regarding specific retention phenomena. For example, a filter made of cellulose acetate filters nitrosamines and phenols that are harmful to health 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 advantage of a spatial filter made of cellulose-2,5-acetate, which should not be underestimated, is due to the optical homogeneity of the cut surfaces of the filters.

All other possible polymers with which spatial filters could be produced according to comparable processes have not become established 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 can. The consistently negative assessment of the smoky 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 feed are not causally linked to the physical filter construction, but to the adsorbing properties of the cellulose-2,5 polymer - can be attributed to 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 "Rκ" of a common room filter is a function of filament titer (fiber fineness), filter diameter, draw resistance and filter length. The following applies:

R _k = f (dpf, DA ΔP) (1),

where mean: dpf filament titer [dtex],

D filter diameter [mm], C filter length [mm] and ΔP tensile resistance [daPA].

There has been no lack of attempts to represent the relationship between these quantities using empirically determined equations. Examples of this can be found in the following publications: "Design of Cigarettes", CL 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 ^® ":

where: Dk = permeability of the filter for condensate,

where: Dk = exp (L * A + B) (3),

A = Kl - K2 * dpf (4),

L = 21 - £ (5) and

B = - (K3 * D ⁴ * ΔP + K4 / dpf + K5) (6).

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 retentive, 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 _, the filament titer dpf, the total titer G [g / 10exp4 * m] and the fiber weight ΠIA [g]

ΔP = f (D, £, dpf, G, ΓΠA) (7). For a given filter rod with a tensile resistance ΔP, a diameter D and a length £, the fiber weight is clearly defined when using a defined filter tow specification. The relationship between fiber weight and tensile resistance cannot be shown in a mathematical equation because of the variety of filter tow specifications available, the filter rod dimensions, and the different residual crimps that can be realized. However, the Cable ^® mentioned above allows the fiber weight to be calculated for a given tensile resistance for each feed tow specification, residual crimp and filter rod dimension.

The fiber weight niA of a filter is defined with the residual crimp and the total titer by the following equation:

IR = 10,000 * mκ l (G * () (8).

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 titers 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 titre. For spatial filters, 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 = (r_A / ΔP s) / dpf <0.7 [10 m / daPA] (9),

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:

ΔPτ 8 = ΔPx * (Dχ / 7.8) ' ⁸ [daPA] (10), where the index X denotes the diameter of the actual sample.

Despite the resulting enormous variety of possible spatial filters, there are restrictions with regard to the achievable condensate retention due to the relationships mentioned (equation 2).

It is technically completely problem-free to manufacture filters with the range of filter tow specifications that are common today to cover the full-flavor cigarette segment just as much as the medium and light cigarette segment. It becomes problematic when a filter performance, as required for the construction of ultra-light cigarettes, of significantly more than 50% is required with a usual filter diameter of 7.80 mm and a filter length of 21 to 25 mm. Since the smoke flows parallel to the direction of the fibers in a spatial filter, this can only be achieved by significantly lowering the filament titer, which would also result in a significant increase in draft resistance if the overall titer were to be maintained. Total titer and filament titer must therefore be reduced equally, with the result that the hardness of the filter is drastically reduced, especially during smoking. This phenomenon is called "hot collapse" by a person skilled in the art and is considered to be completely undesirable.

Specific retention benefits caused by additives can only be achieved with a comparatively high base retention. For example, WO 97/16986 describes additives having an anti-mutagen effect, which only work effectively in conjunction with a likewise high minimum nicotine retention. This requirement clearly limits the spectrum of the filter tow specifications applicable in WO 97/16986 (cf. examples in Table II, page 13).

Another undeniable disadvantage of spatial filters made from cellulose acetate is their poor mechanical disintegration in the environment. This poor disintegration delays the degradation of the cigarette filters that get into the environment. It has been demonstrated that the breakdown of cellulose Acetate fibers can be accelerated effectively by various measures. However, all of these measures work equally towards improving the biodegradability of the polymer cellulose acetate, but not towards making the filters easier to disintegrate. The effect of z. B. measures described in DE-C-43 22 966 and DE-C-43 22 965 is essentially limited by the three-dimensional crosslinking of the filaments in a spatial filter. The microorganisms required to degrade the filter material therefore have insufficient access to the filaments in the field and thus to the biodegradation of the polymer. The polymer's improved biodegradability is thus over-determined or dominated by the poor mechanical disintegration of the spatial filter.

Since the above-mentioned crimp chamber crimp is a three-dimensional crimp, a three-dimensional crimp occurs in the fuse formed in the filter manufacture even without hardening additive, but also, as suggested in DE-C-43 22 966, when using water-soluble adhesive Cross-linking of the filaments in the finished filter, which is so important that the mechanical disintegration of the filter in the environment is also noticeably impeded in these cases. Similar restrictions apply to the photochemical degradation of filaments. The acceleration described in EP-A-0 716 117 and EP-B-0 732 432 is limited by the described structural disadvantages of a spatial filter.

In EP-A-0 880 907 it was therefore proposed to largely prevent cross hooking by using filter tow specifications with extremely low residual ripple (see page 5, equation 8) in the finished filter. Ultimately, this is achieved by drastically increasing the total titers and thus the filter weights. This naturally results in an increase in the train resistance. To compensate for these high tensile resistances, the filament titer must therefore be raised accordingly (see Example II).

As further measures, EP-A-0 880 907 describes a partial cutting of the filters after their manufacture and the use of water-soluble adhesives. 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 met (Example II: S = 0.31 m / daPA).

A completely different process for the production of aerosol filters uses a flat structure as the starting material, such as for example paper, spunbonded nonwovens, textile fabrics or nonwovens (in the following such filters are referred to as “surface filters”). These filters circumvent the above-mentioned restrictions regarding filter performance and A fabric is manufactured by the manufacturer of the feed material, rolled up on bobbins and then sent to the processor. The filter or cigarette manufacturer unrolls the material from the bobbin, forms it into a rod-shaped product and then it in the format section of the filter rod machine to compress it transversely axially, to wrap it with paper and to cut the filter rods to the final length. In addition to this, the fabric is usually, but not necessarily, crimped parallel to the direction of rotation by a creping device before being formed into the rod Lowering the material density and, on the other hand, influencing the pressure drop (tensile resistance) of the filters. 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 marketed, for example, by Filtrona, Hamburg, under the trade name Myria Filter. WO 95/14398 describes a filter made of paper made from artificial, highly fibrillating cellulose fibers of Lyocell fiber, in a mixture with cellulose fibers or also acetate fibers. Furthermore, WO 95/35043 relates to a cigarette filter made of a water-needled fabric, which in turn contains the lyocell fiber as a component there.

In addition to the methods mentioned in the above-mentioned applications, all known methods for forming flat structures can of course be combined. hang with the lyocell fiber, which is extremely interesting for reasons of its fiber diameter after fibrillation, for the production of surface filters.

All of these filters are considered to be readily biodegradable because they are easy to disintegrate due to the lack of cross-linking of the surface layers and the low water resistance of products that were produced in a paper process. After the cigarette filter has been rolled up again to form a sheet under environmental influences, such a sheet also offers, in contrast to a space filter which is difficult to disintegrate, a comparatively substantially larger surface area for microorganisms suitable for biodegradation. Another major advantage of the area filter is the significantly higher nicotine and condensate retention compared to the corresponding draft resistance compared to room filters. This higher filtration performance is due to the physical construction of the surface filter and therefore not dependent on the filter material used.

Nevertheless, when using surface filters in which the filter material does not consist or only partially consists of cellulose acetate, the negative taste influence of the smoke by e.g. B. cellulose fibers judged negatively by the consumer. In addition, these filters, which mainly consist of cellulosic fibers, do not have the high selective retentions to phenols and nitrosamines that are typical of spatial filters made from cellulose acetate.

There has therefore been no shortage of attempts in the past to propose surface filters based on cellulose acetate. For example, DE-A-27 44 796 describes the use of so-called fibrets made of cellulose acetate 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, inter alia, for the production of cigarette filters, starting from a thermoplastic cellulose acetate. All cigarette filters made from the materials described have the advantage that the Filtration performance (measured as nicotine or tar retention) of these filters is significantly higher compared to spatial filters made of cellulose acetate, which are comparable in terms of tensile resistance. It is also known that pure cellulose acetate is not suitable for processing in processes with thermal deformation of the polymer. The problems that occur are described in detail in DE-C-196 09 143.

Another disadvantage is that due to the higher density of the filter mentioned, the material used is comparatively so high that even when using a cheap starting material, such as paper based on paper pulp, the price per filter does not differ significantly from that of a room filter made of cellulose acetate , However, the filters become much more expensive if flat fabrics made of spun endless fibers are used for the production. In these cases, there is a spinning process to produce a crimped tow, which is then cut into a fiber, which is then further processed in an additional work step to form a flat structure as a starting material for the filter manufacturer. Examples of such a procedure are described in the already mentioned WO 95/14398 or also in DE-A-27 44 796.

In view of the disadvantages outlined above, it is understandable that the technology of the surface filter, produced by the multi-stage process (spinning, cutting, nonwoven production), has never prevailed when it is processed into mass-produced articles (full flavor or light segment).

DE-A-1 930 435 describes a distinctly different process for the production of surface filters from cellulose acetate. A conventional filter tow, made from non-thermoplasticized cellulose acetate fibers, is drawn off from a bale, spread out in a conventional preparation part, stretched and with a conventional one Provide plasticizer. In a departure from the usual processing method for the production of spatial filters, the prepared filter tow web is then heated in a heating device and then thermoplastic crosslinked under pressure using profiled, heated rollers. The two-dimensional solidified fabric produced in this way is then combined, compressed axially, with Pa- pier wrapped and cut. As a result, as described in US Pat. No. 4,007,745, a surface filter is produced from endless cellulose ester filaments. An advantage of the process is that, for the first time in terms of the product properties of the filter, it combines the advantages of the surface filter with regard to nicotine and condensate retention with the advantages of the polymer cellulose acetate with regard to specific retention and taste. The one-step, inexpensive conversion of filter tow to a surface filter is also advantageous. However, the filter is characterized by a large number of triangular-shaped smoke channels which are formed from a fleece which has a large number of rectangular depressions. Another disadvantage of this filter construction is that the triangular channels are clearly visible, especially when smoking, which is noticeable as a visual disadvantage of the manufactured products.

However, the process described in DE-A-1 930 435 and the corresponding cigarette feeder of US Pat. No. 4,007,745 have some further significant disadvantages: Due to the thermoplastic fusion of the filaments, large, completely fused areas of low porosity are created (see Fig. 2 to 6), which are ineffective for the filtration of the smoke. As a result, these filters require a material input that is significantly higher than today's spatial filter. For example, filters are described in US Pat. No. 4,007,745, the material use of which exceeds the usual amount used two to two and a half times (see Examples 4 to 7).

Furthermore, the ripple in the non-consolidated surface portions is three-dimensionally oriented (see DE-A-1 930 435, Fig. 6), with the result that the adjacent surface layers, in turn, partially cross-link three-dimensionally when compressing transversely to the feed rod. This is reinforced by the fact that due to the short thermal treatment of the filter tow web before the thermoplastic crosslinking of the fleece, the plasticizer previously applied for plasticization has not yet migrated into the fiber and therefore, corresponding to the hardening of room filters made of cellulose acetate, too contributes to bonding adjacent fleece layers. It should be known that it is the plasticizing described in DE-A-1 930 435 of the products used for cellulose acetate are the same chemical substances as are used for the curing of spatial filters made of cellulose acetate in their function as solvents.

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

Another disadvantage of the teaching of DE-A-1 930 435 lies in the fact that the filter tow web is, as already mentioned, wetted with hardening agent at the time of the formation of the fleece, as a result of which the surface becomes very sticky. This leads to sticking to the calender roll and therefore makes the process extremely difficult, especially at processing speeds of> 100 m / min.

The invention is therefore based on the object of providing surface filters based on endless cellulose ester fibers which do not have the disadvantages of the prior art explained above, in particular of the filter described in US Pat. No. 4,007,745. Even without three-dimensional crosslinking, these should have sufficient hardness, and their mechanical disintegration capability should correspond to that of surface filters which were produced from nonwovens with short-cut fibers. The Filtrona hardness should be based on the market requirements. Furthermore, the area filters are to retain the advantageous properties known from the prior art or, in individual cases, improved properties.

According to the invention, the above object is achieved by a high-performance cigarette filter with mechanical disintegration based on fibers or fusions 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 = (π / ΔP? S) / dpf [10 m / daPA] is calculated in which mean

ΠIA 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 crimp of the filter material has the value of 1 , 45 does not exceed, 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, a water-soluble adhesive is used. If fiber material is mentioned below, then the corresponding design should also apply to filament materials, as far as this makes sense. (With regard to the thermoplastic properties of cellulose ester derivatives, reference is made to the discussion in DE-A-196 09 143 regarding internal and external plasticizers (S1 Z65 ff). The findings made there are of fundamental importance for understanding the following statements. For definition Thermoplasts is also referred to "Römpps Chemielexikon, 8th revised and expanded edition, Vol. 6, Franckh'sche Verlagsbuchhandlung, Stuttgart 1988", page 4229 ".). For the first case of a thermoplastic cellulose ester fiber material, two cases can be distinguished. In the first case, the fiber material is made from an inherently thermoplastic cellulose ester, such as. B. cellulose acetobutyrate. In this, the filter tow can be processed into filters according to the invention without further measures. In the case of a non-thermoplastic starting polymer, such as. Example cellulose-2,5-acetate, this must be thermoplasticized by adding a suitable plasticizer. In this case, the plasticizer must be distributed homogeneously in the fibers. The homogeneous distribution of the plasticizer in the fibers can be demonstrated by a wide variety of methods. These include, for example: recording the evaporation kinetics of the plasticizers. For this purpose, a filter plug can be heated in an inert gas stream and the evaporation kinetics can be verified by combustion in a commercially available flame ionization detector (FID). The evaporation rate one in the Fiber evenly applied plasticizer differs sustainably from that of a superficially applied plasticizer. Since the evaporation is diffusion-controlled, the evaporation kinetics are significantly slower with even distribution than with surface application. Another possibility is to display the evaporation kinetics using differential thermogravimetry. Thirdly, the uniform distribution can be determined by short-term extraction methods in solvents suitable for the polymer with subsequent quantitative analysis of the plasticizer. This method provides a significantly lower analysis value for a homogeneously distributed plasticizer than for the superficially applied plasticizer with the same percentage content. Another possibility to qualitatively differentiate superficial and evenly distributed plasticizers is to investigate using NIR reflection. This method provides a significantly lower analysis value for homogeneously distributed plasticizers than for the superficially applied plasticizers with the same percentage content.

To produce the filter according to the invention, a filter tow is pulled off the bale, pneumatically spread out and stretched by the method customary for spatial filters. Before the actual filter production step, a nonwoven nonwoven with the lowest possible strength is produced in the direction of both surface axes. Surprisingly, it has been shown that this is particularly successful when the plasticizer required for thermoplasticizing the polymer is evenly distributed in the fiber.

In the context of the present invention, the ratio of fiber weight / tensile resistance S based on the filament titer according to the formula described above is greater than approximately 0.7. If this value is undershot, this leads to retention values as are customary in conventional cellulose acetate feeds. The fiber weight / tensile resistance ratio S based on the filament titer is preferably at most about 2, and is in particular in the range from about 0.8 to 1.3. If the preferred value of about 2 for the ratio S is exceeded, then this product no longer meets the desired economic requirements. With regard to the other underlying parameters, the following general conditions preferably apply:

The residual ripple 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.

Within the framework of the teaching according to the invention, the fiber weight can be a maximum of 10 mg / mm filter length, in particular a maximum of 9.0 mg / mm filter length, and preferably at least approximately 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, such a product is not sufficiently economical. A minimum value of about 5 mg / mm filter length is preferably maintained. If this value is undershot, the desired hardness of the cigarette filter of at least 90% can no longer be maintained according to the prior art. The minimum limit for Filtrona hardness of around 90% is based on market requirements. The Filtrona hardness of the cigarette filter according to the invention can preferably be set to about 90 to 95%, in particular about 91 to 93%. (Determination of the Filtrona hardness: A cylindrical rod with a diameter of 12 mm presses vertically with a load of 300 g on a horizontally positioned filter rod with its flat face. The ratio of the compressed diameter to the initial diameter determined by the first touch gives the percentage of the Filtrona Hardness). It proves to be particularly advantageous if a high-performance cigarette filter according to the invention according to the CBDTF test has a weight loss of at least about 40%, in particular at least about 50% by weight, after a test period of 10 weeks.

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 filter tow qualities used varies between 1 and 20 dtex. The disintegrability of the cigarette filters according to the invention is increased by a slight residual ripple IR. This low residual crimp reduces the cross-hooking of the filaments inside 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 filter according to the invention, it is advisable to produce it from a multi-wide fiber strip in accordance with the teaching of DE 43 40 029. According to a further embodiment, the cigarette filter can be produced from a fiber strip which was separated into several strips before entering the strand part of the filter rod machine.

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

The plasticizers used for the thermoplasticization of the cellulose esters used and evenly distributed in the fibers can be selected, for example, from the following groups: glycerol esters (in particular glycerol triacetate), ethylene and propylene carbonate, citric acid esters (in particular acetyl and triethyl acetate), glycol esters (in particular triethylene glycol diacetate) (TEGDA) or diethylene glycol dibenzoate), Carbowax ^® (in particular polyethylene glycols with a molecular weight of 200 to 14,000, such as manufactured by UCC, USA), sulfolane (tetrahydrothiophene-1, l-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 adhesive to be used is well known to those skilled in the art in this technical field. res common. Generally there is a plasticizer and / or adhesive content of about 1 to about 40% by weight, but in special cases the plasticizer content can easily exceed this range without affecting the teaching of the invention.

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

In a further preferred embodiment of the invention, the cellulose ester fibers or filaments contain additives in the form of photo-reactive additives, additives which promote biodegradability, additives with a selective retention effect and / or colored pigments. A finely dispersed titanium dioxide of the anatase type with an average particle size of less than 2 μm is preferably used as the photoreactive additive. Additives which promote biodegradability include in particular: nitrogenous substances whose natural or microbial degradation products release basic amines (for example urea and its derivatives; oligopeptides and proteins such as beta-lactoglobulin; condensation products from carbonyls and amines , for example hexamethylenetetramine; and nitrogen-containing organic heterocycles, in particular carbazoles).

Preferred additives with a selective retention effect are filtration aids, such as those mentioned in WO 97/16986. Organic acids or acidic carboxylic acid esters, polyphenols or porphyrin derivatives are preferably used. By means of suitable measures, the high-performance cigarette filter according to the invention can thus be improved in terms of its biological and photochemical degradability to an extent that is only possible to a limited extent in the case of spatial filters from the prior art.

The advantages associated with the invention are therefore numerous. In particular, the easy disintegration of the filter according to the invention under environmental influences is of great advantage. This can be significantly improved in terms of the biological and photochemical degradability compared to a known spatial filter. In addition, it has increased retention compared to spatial filters, for example made of cellulose acetate, with the same tensile resistance, while at the same time meeting the requirements placed on the filter, in particular by the cigarette manufacturer and the end user, to a high degree. By mixing different starting tows of any filament size (filament titer), it is also possible to set an optimal area volume and filtration capacity accordingly. This way of working also makes it possible to optimize the filter according to its Filtrona hardness. Furthermore, the existing plasticizer, such as triacetin, can have a positive influence on the taste, but at the same time, however, a significantly smaller amount of plasticizer passes directly into the smoke. Accordingly, significantly lower condensate values are found in the high-performance cigarette filter according to the invention.

The invention is described in detail below on the basis of examples, which are not intended to limit the teaching according to the invention. Further exemplary embodiments are obvious to the person skilled in the art in the context of the disclosure according to the invention.

Examples:

Comparative Example 1:

As a comparison example 1, which represents a cigarette filter (spatial filter) common today, a cigarette filter was produced 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 tensile resistance is 60 daPA with an acetate weight of 107 mg. The filters were coated 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 = 0.54 (10 m / daPA) standardized to the filament titer. These filters were tested for their disintegration using the test method (CBDTF test) developed by a CORESTA working group described below. 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 ^" . The temperature, measured by a white standard, is 55 ° C. The samples are irrigated twice a day with deionized water. The samples are shaken once a day mechanically loaded with four steel balls (M = 16g, D = 1, 2 cm) in a steel beaker Weekly after conditioning of the samples, the weight and optionally the volume are determined. To determine the condensate retention of the filter, the 21 mm long filter was attached to one "American blend" tobacco rod coupled and smoked according to CORESTA recommended No. 22 and 23. 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 is then calculated using the following equation:

Rk = EFiltcr / (EFilter -r- Ecambπdgefilter).

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, the filter tow web with a minimum width of 250 mm is introduced into a pair of heated calender rollers and calendered with an effective line pressure of 40 kg / cm. The profiled calender rolls have a diameter of 230 mm and a grooved width of 350 mm and have 10 profile grooves per cm. They are heated to a temperature of 205 ± 3 ° C with a silicone oil. The groove 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 produced in this way is folded into a strand by insertion into an inlet nozzle and wrapped in paper in a commercially available KDF2, from the Körber company, Hamburg, at a strand 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, as shown in Comparative Example 1, are then examined for their disintegrability (the results are summarized in Table 1). The tensile resistance of these filter rods is 51 daPA with an acetate weight of 141 mg. The fiber weight / tensile resistance ratio based on the filament titer is S = 0.83 [10 m / daPA]. The condensate retention, determined as described in Comparative Comparative Example 1, was 42.3%.

The proof of the non-homogeneous distribution of the sprayed triacetin is carried out as follows: A filter plug of length 21 mm produced three months before the examination date is inserted into a V2A steel tube with an inner diameter of 7.5 mm. The inside diameter of the steel tube is tapered on both sides to a diameter of 0.3 mm using suitable technical means. On the inlet side, nitrogen gas is 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 at the latest and the baseline after about 6 minutes.

Example:

300 kg of cellulose acetate flakes were introduced into a double-walled universal mixer with a total volume of 615 liters and a cooling / heating device. The mixing tool 1 is in one piece with three blades all the way around the bottom and placed vertically on the drive shaft. A one-piece, four-bladed chopper tool 2 is attached horizontally to the drive shaft, which prevents agglomerate formation during the addition and diffusion of plasticizer and is operated at a peripheral speed of 21 m / sec (2890 rpm).

Mixer 1 was started up at a peripheral speed of 6.5 m / sec. 65 kg of triacetin were added uniformly over 10 minutes. At this time, the chopper tool 2 is switched on. Mixing was continued intensively for 12 minutes for intimate mixing. In the next 20 minutes, the material was heated to a temperature of 76 ° C. This temperature was maintained for 5 minutes. The mixture was then continuously cooled to 20 ° C. for 30 minutes. The total duration of action of the triacetin on the flakes was 67 min. The mixer was then quickly drained within three minutes. This product obtained by this procedure is very easy to pour and store. The thermoplasticized cellulose acetate granulate is converted into a filter tow of the specification 3.0 Y 55 [filament titer 3.33 dtex; Total titre 61,111 dtex] processed.

This filter tow was processed on a conventional two-stage KDF 2 drafting system from Hauni, Hamburg. In contrast to Comparative Example 2, no additional plasticizer is applied after stretching. After leaving the deflection roller, the filter tow web with a minimum width of 250 mm is introduced into a pair of heated calender rollers and calendered. 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 heated to a temperature of 180 ± 3 ° C with a silicone oil. The groove 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 produced in this way is folded into a strand by introducing it into an inlet nozzle and wrapped in paper in a commercially available KDF2, from the Körber company, Hamburg, at a strand speed of 120 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 91.4%.

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

The proof of the homogeneous distribution of the sprayed triacetin is carried out as follows: A filter stopper with a length of 21 mm produced three months before the examination date is inserted into a V2A steel tube with an inner diameter of 7.5 mm. The inside diameter of the steel tube is tapered on both sides to a diameter of 0.3 mm using suitable technical means. Nitrogen gas is flowed in on the inlet side at a flow rate of 30 ml per minute and connected on the outlet side to a commercially available flame ionization detector (FID). The sample tube is heated in a heating oven at a heating rate of 75 ° C / min 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 the disintegration of comparative examples 1, 2 and the example according to the invention.

Table 1:

It can be seen from the table values above that the disintegration of a product produced according to the invention is surprisingly clearly superior to the values of the comparative examples as the test progresses.

All measured data are summarized in Table 2.

Table 2:

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Claims

claims

1. High-performance cigarette filter with mechanical disintegration on the basis of fibers or filaments of cellulose esters, characterized in that a) the fiber weight (or filament weight) / tensile resistance ratio S based on the filament titer / tensile resistance ratio S is greater than about 0.7, where the S value according to the formula:

S = (π_A / ΔPT ₈ ) / dpf [10 m / daPA]

is calculated, where niA means 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 crimp of the filter material Does not exceed a value of 1.45, c) the fiber weight is a maximum of 10 mg / mm filter length and d) the hardness of the cigarette filter exceeds about 90% of Filtrona hardness.

2. High-performance cigarette filter according to claim 1, characterized in that the cellulose ester material is cellulose acetate.

3. High-performance cigarette filter according to claim 1 or 2, characterized in that the cigarette filter after the CBDTF test has at least about 40% weight loss after 10 weeks of testing.

4. High-performance cigarette filter according to one of claims 1 to 3, characterized in that the cellulose ester material is thermoplastic and the fibers or filaments, if a plasticizer is included, contain this evenly distributed.

5. High-performance cigarette filter according to one of claims 1 to 4, characterized in that a water-soluble adhesive is present on the surface of the fibers or filaments.

6. High-performance cigarette filter according to at least one of the preceding claims, characterized in that the residual ripple is between approximately 1.05 and 1.4, in particular between approximately 1.1 and 1.3.

7. High-performance cigarette filter according to at least one of the preceding claims, characterized in that the cigarette filter consists of a multiple width

Fiber strips have been produced.

8. High-performance cigarette filter according to at least one of the preceding claims, characterized in that the cigarette filter has been produced from a fiber strip which was previously separated into several strips.

9. High-performance cigarette filter according to at least one of the preceding claims, characterized in that the thermoplastic fibers or filaments contain cellulose acetate, in particular cellulose 2,5-acetate, cellulose butyrate, cellulose acetobutyrate, cellulose acetopropionate and / or cellulose propionate.

10. High-performance cigarette filter according to at least one of the preceding claims, characterized in that when a plasticizer is used, the plasticizer content is between approximately 1 and 40%.

11. High-performance cigarette filter according to at least one of the preceding claims, characterized in that when a plasticizer is used, this is triacetin, triethylene glycol diacetate and / or diethyl citrate.

12. High-performance cigarette filter according to at least one of the preceding claims, characterized in that the thermoplastic fibers or filaments on cellulose acetate with a degree of substitution of about 1.5 to 3.0, in particular about

2.2 to 2.6 are based.

13. High-performance cigarette filter according to at least one of the preceding claims, characterized in that the water-soluble adhesive agents are in the form of polyethylene glycols, water-soluble esters or ethers, starch and / or starch derivatives, p-polyvinyl alcohols, p-polyvinyl acetates.

14. High-performance cigarette filter according to claim 1, characterized in that the fiber weight (or filament weight) based on the filament titer / tensile resistance ratio S is at most about 2, in particular in the range from about 0.8 to 1.3.

15. High-performance cigarette filter according to at least one of the preceding claims, characterized in that the fiber weight (or filament weight) is at least about 4 mg / mm filter length, in particular about 5 to 8 mg / mm filter length.

16. High-performance cigarette filter according to at least one of the preceding claims, characterized in that the Filtrona hardness of the cigarette filter is approximately 90 to 95%, in particular approximately 91 to 93%.

17. High-performance cigarette filter according to at least one of claims 3 to 16, characterized in that the cigarette filter has a weight loss of at least about 50 percent by weight according to the CBDTF test.

18. High-performance cigarette filter according to at least one of the preceding claims, characterized in that the cellulose ester fibers or filaments contain additives in the form of photoreactive additives, additives which promote biodegradability, additives with a selective retention effect and / or colored pigments.

19. High-performance cigarette filter according to claim 18, characterized in that a finely dispersed titanium dioxide of the anatase type with an average particle size of less than 2 μm is used as the photoreactive additive.

20. High-performance cigarette filter according to claim 18, characterized in that organic acids or acidic carboxylic acid esters, polyphenols and / or porphyrin derivatives are used as additives.

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