KR100579703B1 - 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}

The present invention relates to a filter tow used to manufacture a cigarette filter having a relatively low filtration performance, which can be used in a whole cigarette having a ventilation degree of 25% or more. At the same time, drag resistance retention characteristics are selected to maintain acceptable drag resistance and acceptable filter plug weight in the cigarette.

Most of the tobacco filters used today are made of filter tows consisting of continuous 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 condensate content in the smoke:

Full-flavor

Medium

Light and

Ultralight 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 are tobacco lengths from 85 to 120 mm and diameters of 7.8 ± 0.2 mm. However, there are special products that differ markedly from most of the merchandise in their structure. To meet many of these product requirements, the filter tow industry offers 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; Crimp ratio (%) 25, up to 38; Number of crimps per cm 10, up to 20.

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.

* Length:

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

* Retention value:

Condensate: 42%

Nicotine: 38%

Carbon monoxide: no.

Due to the new EU upper limit regulation (2000 / C 150E / 03), especially forward-looking products have to be drastically changed in their structural characteristics, since 1 January 2004, nicotine values as well as condensate values, and especially This is because CO must be regulated at the upper limit. What is required to change the product to cope with the new European regulations is that the maximum allowable amount with the optimum smoke flavor needs to reach as accurately as possible 10 mg condensate value, 1 mg nicotine value and 10 mg CO value per cigarette. will be. In other words, in the future, the CO / tar ratio of 1: 1 should be aimed at forward products.

Based on model calculations that only consider a change in filter airflow, it can be estimated from the above example that about 35% of the airflow of the filter is required to reduce the CO value from 14 mg per cigarette today to 10 mg in the future. have. 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 smoked taste means that the drag resistance of a cigarette should not drop significantly below its current value of 100 mm orders. 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 equation 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)

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

Therefore, drag resistance / stay ratio must be redefined for future products in the "Forward" category. And in order to employ a CO / tar ratio of 1: 1 and to ensure an acceptable product in the drag resistance of tobacco, 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 performance of a filter made with the filter tow according to the present invention, given the drag resistance of the filter, must be considerably lower than the retention value typical of today to achieve a CO / tar ratio of 1: 1. .

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 reduce the filter performance (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 to Rhodia Acetow's calculation program Cable ^® (Capability Line Expert; copyright Germany, Freiburg, Rhodia Acetosa 1998).

Thus, depending on the state of the art, the retention of the filter is reduced by the rise of the filament titer. Model calculations suggest that the filter titer must rise to at least 0.5-1.5 dtex in order to meet the requirements of filtration performance in the future. However, today's marketable filter tow specifications (average total titers of all specifications are about 35 ktex) are not suitable to meet the required drag resistance range at the minimum filament titers required (Rhodia Acetosa's calculations). Program Cable ^® ). Normally, according to the state of the art, this problem can only be solved by increasing the total titer drastically above 45,000 dtex for monoacetate filters.

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

The foregoing discussion is limited to forward tobacco grades. In general, however, when pursuing a CO / tar ratio of 1: 1, a discussion of the extension of the drag resistance range holds for all filament titers. That is, the tasks shown below will generally encompass the filament titer range of the current 1.6 to 8.8 dtex (which is established throughout).

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 performance equivalent to a CO / tar ratio of 1: 1.

To meet the above requirements, the present invention provides two approaches that can be combined as needed but are essentially independent of each other.

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 coherent bundles of fibers of filaments of at least 600 identical filament titers. And they differ by at least 1 dtex between the fiber bundles in the filament titer. This solution provides particularly excellent results in filtration performance, because filters made with such non-uniformly distributed mixed tows are made with conventional tows with uniform filament titer distributions or with mixed tows with uniform filament distribution. This was because it was surprisingly found to have a much lower tar retention than the prepared product (compare FIG. 3).

The second solution is realized by a filter tow with a crimp structure that is more powerful and at the same time much finer than today's conventional products. Thus in claim 4 a filter tow having a crimp ratio of at least 40% is described, wherein the filament has at least 22 crimps per cm filament length. This filter toe meets the upper limit requirements, in particular regarding the filter tow drag resistance. The values achieved are more preferred when the crimp ratio is at least 42% and the filaments have at least 25 crimps per cm.

In order to achieve optimum filtration performance simultaneously, the filter tow has a filament titer of 3.33 dtex or more, and a total titer of 44,000 dtex or less, preferably 40,000 dtex or less. As a result of the limitation of the total titer, the filter toe consumption is still increased to an acceptable level.

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

Crimp ratio I _x is a measure of wrinkle strength. The crimp ratio of the filter tow is determined by a tensile 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 (%)

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

Crimp ratio values of current filter tow specifications are usually 25 to 35%. Rhodia Acetous is the only manufacturer in the world to offer specifications under the name SK covering a crimp ratio range of 35% up to 38% in the filament titer range of ≤2.78 dtex.

As already mentioned, the crimp ratio 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 crimp ratio is type 2.1 Y 35 HK (filament titer: 2.33 dtex; total titer: 38,900 dtex; cross-sectional shape of filament: Y-shaped; crimp ratio 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; crimp ratio 36%) is shown in FIG.

The solution of this problem is achieved by producing a filter tow having a crimp ratio of at least 40%, preferably at least 42%. This index is inevitably required to cover the drag resistance range. The crimp ratio is affected on the one hand by the crimp frequency and on the other hand by the amplitude (maximum height). Crimp number represents a measure for wrinkle fineness. Currently, typical numerical ranges are from 10 to up to 20 crimps per cm filament length. The SK tow mentioned above is 15-18 crimps per cm.

Surprisingly, it has been found that such an index can only be achieved in the allowable strength of the filter tow only when the pleats are made very finely. The filter tow according to the invention thus has an average of at least 22, preferably at least 25 crimps 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 having a drag resistance level comparable to filters manufactured according to today's conventional specifications. 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 working 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 present invention (Example 1: 4.5 Y 35) compared 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 ultra 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 with up to 19.7 crimps per cm can be made by the method described therein. There is no mention of crimp ratios in this document. However, from the data provided there (drag resistance, toe-standard and mechanical control) the crimp ratio can be estimated with the aid of the above cable program, 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 pleating step. There are listed products with 16 crimps per cm. There is also no statement about the crimp ratio. It can be seen that when the total of the softening components at the time of the pleating process does not exceed 25% by weight, ultra fine folds can be produced effectively and without 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 of the sample at 150 ° C. (20 minutes), 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 No. 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 2 and 22 rows after the German patent No. 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 decreases in the case of the same drag resistance, but due to the uniform distribution of the filaments the residence time of the filter is considerably increased.

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 are interconnected to each other of filaments of at least 600, preferably at least 1,000 identical filament titers, each of which is in the filament titer. At least 1 dtex or more, preferably 1.5 dtex or more. The filter tow comprises at least two regions, preferably at least five regions of the filament bundle having the same filament titer. The advantage of this embodiment is that the filament bundles each having the same filament titer agglomerate in the filter and thus form regions of low but individually high drag resistance as a whole. Filters made with such mixed titer tows have similar properties in drag resistance and retention, as described for example in the JP2000000085 for classical core-mantle filters. Regarding this filter tow, there is no limit regarding the crimp ratio and the number of crimps per cm. In a preferred embodiment of the invention a product of course having a crimp ratio 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 to such an extent that the filtration performance of the product, which is significantly lowered when a drag resistance is given using the teaching according to claim 10, can be achieved. The limitations on total titers mentioned above may limit material consumption in filter manufacture. 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 further saving material consumption.

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 that of FIG. 1 regarding the filter tow of Example 1, Comparative Example, and Traditional Example; FIG.

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

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

Comparative Example (Toe of Type 4.5 Y 55)

A spinning solution having a concentration of 30% by weight of cellulose acetate in acetone is prepared, filtered and extruded through a nozzle. The water content of the spinning solution is 1.5%. A spinneret is selected with respect to the number of holes, the size of the holes and the number thereof so that a tow of 4.5 Y 55 is finally 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 crimp ratio of 30.5%. The total of plasticizing components is 22.3%. The rupture strength of the tow is 143 N. The number of crimps is 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 Haunis. Lint formation during the processing of the product was not severe and was estimated to be around 0.5 g / ton when the consumption per ton of material was estimated. The characteristic curve of the product shown in FIG. 2 covers the drag resistance range 310-450 mm head.

Example 1:

A spinning solution having a concentration of 30% by weight of cellulose acetate in acetone is prepared, filtered and extruded through a nozzle. The water content of the spinning solution is 3%. Finally, the spinning nozzle is selected in terms of the number of holes, the size of the hole and the number of tows to produce a 4.5 Y 35 tow. Adjust the lubricant supply to obtain 1.3% oil layer. After drying and packaging, the band is pleated using a conventional ram type pleat to obtain a filter tow with a crimp ratio of 43.5%. The total of softening components is 29%. The rupture strength of the tow is 111 N. The number of crimps is 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 Haunis. Lint formation during the processing of the product was not severe and was estimated to be about 2.8 g / ton when the consumption per ton of material was estimated. The characteristic value curve of the product shown in FIG. 2 covers the drag resistance range 298-505 mm head.

Example 2:

A spinning solution having a concentration of 30% by weight of cellulose acetate in acetone is placed, filtered and extruded through a nozzle. The water content of the spinning solution is 3%. Finally, the spinning nozzle is selected in terms of the number of holes, the size of the hole and the number of tows to produce an average of 4.5 Y 32 tow. Unlike the above embodiments, however, the spinning machine is divided into six zones, in which alternate high filament titers (1,185 filaments 6.9 den = 7.65 dtex per zone) are spun and low filament titers (1,185 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 bands are pleated using a conventional ram type pleat to obtain a filter tow with a crimp ratio of 39.8%. The total softening component is 27.5%. The rupture strength of the tow is 129 N. The number of crimps is 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 about 0.9 g / ton when the consumption per ton of material was estimated. The characteristic value curve of the product shown in FIG. 2 covers the drag resistance range 267-487 mm head.

Claims (10)

A filter tow consisting of pleated endless cellulose acetate filaments, The filaments are formed of two or more interconnected fiber bundles each having the same filament titer, each of which consists of more than 600 filaments, wherein the filament titers of the filaments differ by more than 1 dtex between the fiber bundles Tow. The filter tow of claim 1, wherein the filaments form five or more interconnected fiber bundles each having the same filament titer. The filter tow of claim 1 or 2, wherein each of the fiber bundles comprises at least 1,000 filaments. The filter tow of claim 1 or 2, wherein the filament titer of the filaments differs by at least 1.5 dtex between the fiber bundles. The filter tow according to claim 1 or 2, wherein the crimp ratio is 33% or more and the number of crimps per cm is 15 or more. The filter tow according to claim 1 or 2, wherein the crimp ratio is 35% or more. The filter tow according to claim 1 or 2, wherein the crimp ratio is 40% or more and the number of crimps per cm is 22 or more. A filter tow consisting of pleated endless cellulose acetate filaments, Wherein said filter tow has a crimp ratio of at least 40% and said filaments have at least 22 crimps per cm filament length. 9. The filter tow of claim 8, wherein the crimp ratio is at least 42% and the filaments have at least 25 crimps per cm. 10. The filter tow of claim 8 or 9, wherein the filament titer is at least 3.3 dtex and the total titer is at most 44,000 dtex.

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