KR20040015229A - Filter tow - Google Patents

Abstract

Abstract of the Disclosure The invention relates to a filter tow made from crimped endless cellulose acetate filaments, whereby the filaments form at least two connected fibre bundles with the same filament titre of at least 600 filaments. The filament titres differ from bundle to bundle by at least 1 dtex Furthermore a filter tow is disclosed with a crimp ratio of more than 40%, said filaments comprising at least 22 crimp turns per filament length.

Description

Filter Tow {FILTER TOW}

Most of the tobacco filters used today are made of filter tows consisting of endless cellulose-2,5-acetate-filament. This filter is called an acetate filter. Cigarettes manufactured and sold in the European Union are classified into the following classes according to the condensation value (the amount of condensate) in the smoke:

-Chunyang

-Secondary

-Docile and

-Ultra soft tobacco.

All these cigarettes are ventilated on the basis of the upper limit on condensation (90/239 / EEC). Aeration depends on the one hand on the condensate target and on the other hand on the filtration performance of the filter used.

The following table gives an overview of the current typical values:

Rating mg condensate Filament titer % Aeration conversion <12 2.8-3.3 dtex <25 Secondary 8-10 ≤3.3 dtex <35 Docile 4-8 2.1-2.8 dtex 30-50 Ultra softness <4 1.7-8.8 ＞ 50

The overwhelming number of commodities available today have a diameter of 7.8 ± 0.2 mm with a cigarette length of 85-120 mm. However, there are special products that differ markedly from most of the merchandise in their structure. To meet these many product requirements, the filter tow industry provides a number of different tow types, which can be represented generally by the following features: filament titers 1.6-8.8; Total dtex 17,000-60,000; Wrinkle index (crimp ratio) (%) 25, up to 38; number of crease bends per cm; 10, up to 20.

The present invention provides a cigarette filter having a relatively low filtration power, in which the drag resistance-retention time characteristic of the filter is selected so that it can be used in a forward tobacco having an appropriate drag resistance of the cigarette and a ventilation degree of 25% or more in the filter use weight. Relates to a filter tow.

1 is a characteristic value curve diagram showing the relationship between the weight of the filter tow and the operating resistance range;

FIG. 2 is a characteristic value curve diagram similar to FIG. 1 for the filter tow of Example 1, Comparative Example and Traditional Example; FIG.

FIG. 3 is a plot showing relative tar residue for titer and distribution of filaments in various cases.

In the following description of the subject matter of the invention, reference will be made solely to forward product grades. Typical grade tobacco cigarettes have the following typical characteristics, where all indications should only be seen as baseline (base). These serve only as a calculation basis for further embodiments.

* Grinding:

Cigarette: 84mm

Filter: 21 mm

Tobacco body: 63 mm

Tipping (filter end): 26 mm

* diameter:

Filter: 7.80 mm

Cigarette: 7.85mm

* Drag resistance

Filter: 66mm head

-Tobacco body: 50 mm chickenpox

Cigarette: 100mm chickenpox

* Filter tow specification: 3.0 Y 35 (filament titer: 3.33 dtex; total titer: 38,900, cross-sectional shape of filament: Y)

* Mixed Tobacco: American Blend

* Aeration:

Breathability: 20%

Ventilation location 11 mm from end of mouth

* Smoke value:

Condensate: 12 mg

Nicotine: 0.9 mg

Carbon monoxide: 14 mg

* Residence time:

Condensate: 42%

Nicotine: 38%

Carbon monoxide: no.

Due to the new EU capping limit (2000 / C 150E / 03), especially forward-looking products have to be radically altered in their structural characteristics, since 1 January 2004, nicotine as well as condensate values-and especially CO − must be regulated at its upper limit. When converting a product according to the new European regulations, what is required is exactly as much as possible the upper limit of the permissible maximum smoked taste (smoke flavor) to 10 mg condensate, 1 mg nicotine and 10 mg CO per cigarette (one shell). So that changes in the product must be shaped. In other words, in the future, forward-looking products will seek a ratio of CO / tar of 1: 1. As can be seen from the above table, in this example, this ratio value is 1.17.

Based on model calculations that only consider a change in the filter airflow, it can be extracted from the calculation that about 35% of the filter airflow is required to reduce CO from 14 mg per cigarette today to 10 mg in the future. In other cases, an increase in air permeability in a product that has not changed will inevitably lead to a drop in tobacco drag resistance (flow resistance of intake during smoking).

But for consumers, optimal smoking taste means that the drag resistance of cigarettes should not drop significantly below today's 100mm head. Thus, the increase in ventilation will greatly lower the drag resistance of the cigarette when maintaining other filter parameters such as diameter, location of the ventilation zone and filter length. The tobacco drag resistance obtained therefrom can be calculated according to the following formula based on the laminar flow model:

P _v = P ₀ -V × (P ₀ -P _F × L _v / L _F )

Where

P _v : Drag resistance of aerated cigarettes (mm head)

P ₀ : Drag resistance of non-vented cigarettes: = Drag resistance (filter + cigarette body) (mm head)

P _F : Drag resistance of the filter (mm head)

V: Filter air permeability (% / 100)

L _v : Distance from the mouth end to the ventilation zone (mm)

L _F : Filter Length (mm)

The open drag resistance is therefore only 88% chicken head at 35% aeration for the model cigarettes shown (instead of the original 100 mm head). Such a drop in tobacco drag resistance is clearly recognizable to the smoker and therefore must be corrected by an increase in the filter drag resistance (about 80 mm head in the example above) to maintain the consumer's smoking sensation. Increasing the filter drag resistance inevitably leads to an increase in the CO / tar ratio, because only the tar value is affected by the filter drag resistance, not the CO-value (the tar value decreases when the drag resistance rises). do).

Thus, for future products of category "Forward", the drag resistance-residence time ratios must be newly defined. And in order to employ a 1: 1 CO / tar ratio and to ensure an acceptable product in the drag resistance of the cigarette, the filter tow used in the manufacture of the filter must meet these requirements. In this regard, the following requirements may be defined:

1. The filter tow should be suitable for being able to manufacture a filter having a drag resistance which is conventional (but preferably still high) today.

2. The filtration power of the filter made with the filter tow according to the invention should be significantly less than that of today's conventional residences, in order to achieve a CO / tar ratio of 1: 1, given the drag resistance of the filter.

3. Additional material consumption due to the increase in filament titers should be kept within limits.

The retention of the filter depends entirely on the drag resistance and filament titer given the filter diameter and length. For example, the rise of the filament titer and the drop of drag resistance cause a decrease in filter power (and vice versa). Because this relationship is a very complex property, people use today's filter calculation programs to estimate the magnitude of such changes. For example, we will refer here to the calculation program Cable® by Rhodia Aceto (Capability Line Expert, copyright 1998 by Rhodia Acetow, Freiburg, Germany).

Thus, depending on the state of the art, the residence time of the filter is reduced by the rise of the filament titer. Model calculations suggest that in the future the filter titer must be raised to at least 0.5-1.5 dtex to meet the requirements of filtration power. Today's market filter tow specifications (the average total titer of all specifications is about 35 ktex), however, are not suitable to also cover the drag resistance range required for the minimum filament titer required (Rhodia Aceto) Calculation program Cable®). Normally, according to the state of the art, this problem can only be solved by the simultaneous rapid rise of the total titer to well exceed 45,000 dtex for the monoacetate filter.

Solutions such as, for example, filter tow of type 4.5 Y 55 (see FIG. 2) by conventional technical level, actually satisfy drag resistance-and retention requirements, but consequently consume more than 35% more filter tow than today's products. something to do.

The affirmation in the statement so far will be limited to forward tobacco grades. In general, however, when pursuing a ratio of CO / tar of 1: 1, the statement regarding the extension of the drag resistance range holds for all filament titers. In other words, the tasks shown below will generally encompass the filament titer range of the current 1.6-8.8 dtex (established throughout that range).

It is therefore an object of the present invention to provide a filter tow that makes it possible to produce a filter having a filtration power corresponding to a CO / tar ratio of 1: 1.

In order to meet the above requirements, according to the present invention, two fundamentally independent solutions are recommended in which their features may be combined in some cases.

The first solution according to the invention relates to a filter tow of pleated, endless cellulose acetate filaments, wherein the filaments form two or more interconnected fiber bundles of filaments of more than 600 identical filament titers They differ by at least 1 dtex between the fiber bundles in the filament titer. This solution provides excellent results, particularly with regard to filtration power, because filters made with such non-uniformly distributed mixing toes can be fed with conventional tows with uniform filament titer distributions or with mixing tows with uniform filament distribution. This was because it was surprisingly found to have much less tar residue than the manufactured product (compare FIG. 3).

The second solution is realized by a filter tow which is more powerful than today's conventional products and at the same time has a much finer pleat structure. Thus in claim 4 a filter tow with a pleat index of at least 40% is indicated, the filaments having at least 22 pleat bends per cm filament length. This filter toe meets the highest requirements, particularly with regard to the filter tow drag resistance. The filaments preferably have more than 25 wrinkled bends per cm and will surely result in exceeded achievements when the wrinkle index is at least 42%.

At the same time, to obtain optimal filter power, a filter tow having a filament titer of 3.33 dtex or more and a total titer of 44,000 dtex or less, preferably 40,000 drex or less is recommended. The consumption of the filter tow is increased to the extent that is still acceptable with the limitation of the total titer.

Embodiments and advantages of both solutions according to the present invention are described as follows:

Wrinkle index I _x is a measure of wrinkle strength. The wrinkle index of the filter tow is determined by the traction test (force / tension relationship). This index is defined as the ratio of the increased length (L ₂ ) minus the starting length under test load divided by the starting length (L ₁ ) under preload:

I _x = (L ₂ -L ₁ ) / L ₁ * 100 (%)

There the test load is 25 N and the preload is 2.5 N. The fixed length is 250 mm. The wrinkle index is measured at a constant speed of 300 mm / min using the G02 instrument from Hamburg-Borkwald. Ten individual measurements are taken for each measurement. The test is carried out at standard climate: 20 ° C. and 60% relative air humidity (the measurement of the wrinkle index is described in the Cable program under the “Help” button).

The pleated index values of today's filter tow specifications are usually 25 to 35%. Rhodia Aceto is the only manufacturer in the world to offer specifications under the name SK covering the filament titer range of ≤2.78 dtex, covering a wrinkle index range of more than 35% up to 38%.

As already mentioned, the wrinkle index is a measure of the severity of the wrinkles, and thus the state (position) of the characteristic curve. The characteristic value curve in this case is to be understood as the performance range of the filter toe indicating in which drag resistance range the filter tow can be treated under normal processing conditions given the diameter and filter rod length. The characteristic curve thus represents the relationship between drag resistance and weight for these working ranges. The relationship between the characteristic curve state and the wrinkle index is type 2.1 Y 35 HK (filament titer: 2.33 dtex; total titer: 38,900 dtex; cross-sectional shape of filament: Y-shaped; wrinkle index 32%) and type 2.1 Y 35 SK ( An example of a filter tow of filament titer: 2.33 dtex; total titer: 38,900 dtex; cross-sectional shape of filament: Y-shaped; wrinkle index 36%) is shown in FIG.

The solution of this problem is achieved by making a filter tow having a pleat index of at least 40%, preferably at least 42%. This index is inevitably required to cover the drag resistance range. The wrinkle index is affected on the one hand by the frequency of the wrinkle bands and on the other hand by the amplitude (maximum height). The number of wrinkle bands represents a measure for wrinkle fineness. Typical of these figures is today from 10 to up to 20 corrugated bends per cm filament length. The SK-toe mentioned above is 15-18 pleated bands per cm.

Surprisingly, it has been found that such an index can only be achieved in the breaking strength of the acceptable filter tow only when the pleats are made very finely. The filter tow according to the invention thus has an average of more than 22, preferably more than 25, pleated bends per cm filament length in addition to an index of at least 40% in the filaments. Such a filter tow can be processed on a conventional filter rod machine to obtain filters that are at a drag resistance level comparable to filters manufactured according to today's conventional specifications. Figure 2 shows a typical filter tow of type 3.0 Y 35 (filament titer: 3.33 dtex; total titer: 38,900 dtex) or conventional type 4.5 according to the present invention compared to conventional 4.5 Y 55 and conventional 4.5 Y 35. The operating range of the tow of Y 35 (filament titer: 5.0 dtex; total titer: 38,900 dtex) is shown.

From Fig. 2, in the solution according to the invention (Example 1: 4.5 Y 35) in comparison to today's situation (3.0 Y 35), substantially more material is consumed by the increase in the titer of the filament, but this more material Consumption is noticeably less severe than traditional solutions (4.5 Y 55), usually by skill level.

A range of conditions must be maintained in the manufacturing process to make super fine wrinkles good. The filter tow band includes the following components that soften the acetate filament before the pleating process: water, acetone and a lubricant. It is known that these softening ingredients negatively affect the wrinkle process. Thus, for example, US Pat. No. 5,225,277 describes the effect of acetone and band temperature on the stability of wrinkles. Products having up to 19.7 pleated bands per cm can be produced by the methods described therein. However, this document does not mention the wrinkle index. However, from the data provided there (drag resistance, toe-standard and machine control) the wrinkle index can be estimated with the aid of the Cable-program described above, which is clearly less than 35%.

Japanese Laid-Open Patent Publication No. 56-53223 describes the effect of steam treatment of a band before entering the corrugation stage. There are products with 16 pleated bands per cm. There is also no statement about the wrinkle index. When the total of the softening components at the time of the wrinkle process did not exceed 25% by weight, it was confirmed that ultra fine wrinkles can be produced effectively and without any dramatic all kinds of filament damage. It does not matter what concentration the individual components are. The sum of the individual components is determined by gravimetry by laboratory drying (20 minutes) of the sample at 150 ° C., which is removed directly from behind the creasing machine.

As already mentioned, one of the solutions of the problem according to the invention relates to a so-called filter tow with a mixing titer.

German patent 29 16 062 describes such a filter tow and a tobacco filter made therefrom. Contrary to the filter tow according to the invention, there is a distribution of filaments as uniform as possible (compare after step 2 and 22 in German patent 29 16 062). As a result, in the embodiment according to German Patent No. 29 16 062, the material of the filter to be produced is reduced in case of the same drag resistance but the residence time of the filter is considerably increased due to the uniform distribution of the filaments.

The object of the invention described herein is also to save material while at the same time allowing the residence time of a filter made of filter tow to be much smaller than that achieved when the filter is made of filter tow with a single filament titer. . This means that in the product according to the invention the filaments form interconnected fiber bundles of filaments of at least 600, preferably at least 1000 of the same filament titer, the filaments being between the fiber bundles in the filament titer. At least 1 dtex or more, preferably at least 1.5 dtex or more. The filter tow comprises at least two regions, preferably more than five regions of the bundle with the same filament titer. An advantage of this embodiment is that the filament bundles of the same filament titer agglomerate (aggregate) in the filter and thus form low and individually high drag resistance regions. Filters made of such mixed titer tow have similar properties in drag resistance and residence time, as described for example in the JP2000000085 for classical core-mantle filters. Regarding this filter tow, there is no limit regarding the wrinkle index and the number of wrinkle bends per cm. In a preferred embodiment of the invention a product of course having a wrinkle index of at least 33%, preferably at least 35% is produced.

The advantages of the invention according to claims 8 to 10 can be summarized as follows: The combination of the features according to the invention gives access to operating ranges relating to drag resistance which are not available in today's technology. This makes it possible to raise the filament titer so that the filtration power of the product, which is significantly lowered when a drag resistance is given by using the teaching according to claim 10, can be achieved. The limitations on total titers mentioned above may limit the material consumption in the manufacture of the filter. However, particular preference is given to combining the embodiment according to one of claims 1 to 7 with one or several of claims 8 to 10. This practice makes it possible to further reduce the total titer to be used, thereby raising the possibility of further saving material consumption.

The invention is explained in more detail according to the following examples.

Comparative Example (Toe of Type 4.5 Y 55)

A spinning solution with a concentration of 30% by weight of cellulose acetate in acetone was placed, filtered and then extruded through nozzles. The water content of the spinning solution is 1.5%. Finally, the spinning nozzles select the number of holes, the size of the holes, and the number of them so that a tow of 4.5 Y 55 is produced. The lubricant supply is adjusted to obtain a 0.5% oil overlay. After drying and packaging, the band (tape) is pleated using a conventional ram type pleat to obtain a filter tow having a pleat index of 30.5%. The total softening component is 22.3%. The burst strength of the tow was measured to be 143N. The number of corrugated bends was 15.8 per cm filament length.

The product was processed into filter rods having a length of 126 mm and a diameter of 7.8 mm using a conventional filter rod machine KDF2 / AF2 from Hamburg Haunie. Lint formation during the processing of the product was not severe and was estimated to be about 0.5 g per tonne when the amount of wear of the ton material was estimated. The characteristic curve of the product shown in Figure 2 covers the drag resistance range 310-450 mm head.

Example 1:

A spinning solution with a concentration of 30% by weight of cellulose acetate in acetone was placed, filtered and then extruded through nozzles. The water content of the spinning solution is 3%. Finally, the spinning nozzles select the number of holes, the size of the holes and the number of them so that a tow of 4.5 Y 35 is produced. Adjust the lubricant supply to obtain 1.3% oil layer. After drying and packaging, the band obtained is pleated using a conventional ram type pleatter to obtain a filter tow having a pleat index of 43.5%. The total of softening components is 29%. The burst strength of the tow was measured to be 111N. The number of corrugated bends was 26 per cm filament length.

The product was processed into filter rods having a length of 126 mm and a diameter of 7.8 mm using a conventional filter rod machine KDF2 / AF2 from Hamburg Haunie. Lint formation during the processing of the product was not severe and was estimated to be about 2.8 grams per ton when the amount of toner material wear was estimated. The characteristic curve of the product shown in Figure 2 covers the drag resistance range 298-505 mm head.

Example 2:

A spinning solution with a concentration of 30% by weight of cellulose acetate in acetone was placed, filtered and then extruded through nozzles. The water content of the spinning solution is 3%. Finally, the spinning nozzles select the number of holes, the size of the holes and the number of them so that an average of 4.5 Y 32 tow is produced. Unlike the above embodiments, however, the spinning machine is divided into six zones, in which alternately high filament titers (1185 filaments 6.9 den = 7.65 dtex per zone) are spun and low filament titers (1185 filaments 7.1 den =). 2.3 dtex per zone) was spun. Adjust the lubricant supply to obtain 1.3% oil layer. After drying and packaging, the band obtained is pleated using a conventional ram type pleat machine to produce a filter tow having a pleat index of 39.8%. The total softening component is 27.5%. The burst strength of the tow was measured to be 129 N. The number of corrugated bends was 23.1 per cm filament length.

The product was processed into filter rods having a length of 126 mm and a diameter of 7.8 mm using a conventional filter rod machine KDF2 / AF2 from Hamburg Haunie. Lint formation during the processing of the product was not severe and was estimated to be about 0.9 grams per ton when the amount of toner material wear was estimated. The characteristic curve of the product shown in Figure 2 covers the drag resistance range 267-487 mm head.

Claims (10)

The filaments are pleated endless cellulose, characterized in that they form at least two fiber bundles, each having the same filament titer, of at least 600 filaments that differ by at least 1 dtex between the fiber bundles in the filament titer. Filter toe with acetate filaments. 4. The filter tow of claim 1, wherein the filaments form more than five interconnected fiber bundles each having the same filament titer. 3. The filter tow of claim 1 or 2, wherein each fiber bundle comprises more than 1000 filaments. 4. The filter tow of claim 1, wherein the filament titer of the filaments differs by more than 1,5 dtex between the bundles of fibers. The filter tow of claim 1, wherein the wrinkle index (crimp ratio) is greater than 33% and the number of wrinkled bends per cm is greater than 15. 6. The filter tow of claim 1, wherein the pleat index is greater than 35%. The filter tow of claim 1, wherein the pleat index is greater than 40%, preferably greater than 42%, and the number of pleat bends per cm is greater than 22. A filter tow of pleated endless cellulose acetate filaments, wherein the filter tow has a pleat index of greater than 40% and the filaments have at least 22 pleat bends per cm filament length. 9. The filter tow of claim 8, wherein the pleat index is greater than 42% and the filaments have more than 25 pleat bends per cm. 10. Filter tow according to claim 8 or 9, characterized in that the filament titer is greater than 3.3 dtex and the total titer is less than 44,000 dtex, preferably less than 40,000 dtex.