WO2002032238A2

WO2002032238A2 - Highly compressed filter tow bales

Info

Publication number: WO2002032238A2
Application number: PCT/EP2001/012154
Authority: WO
Inventors: Acetow Gmbh Rhodia
Original assignee: Messmer, Ludwig; Teufel, Eberhard; Kramis, Alois; Gerlitzki, Manfred; Meier, Friedrich; Sexauer, Wolfgang
Priority date: 2000-10-20
Filing date: 2001-10-19
Publication date: 2002-04-25
Also published as: AU1697502A

Abstract

The invention relates to a highly compressed filter tow bale with a packing density of more than 450 kg/m3, having on the surface thereof an average Shore hardness of less than 50, with no localised values of hardness greater than 60 and a tow width in the bale of less than 50mm, when the tow has a total titre of more than 30,000 tdex, or the tow width in the bale is a maximum of 1.7 * 10-6 (m/dtex) * total titre when the tow has a total titre of less than 30,000 dtex, with an aggregation value of over 20 and effective layer width of less than 65mm.

Description

Highly compressed filter tow bale

The invention relates to a highly compressed bale of filter tow for cigarette filters.

The majority of the cigarette filters used today are made from filter tow, which consists of endless cellulose-2.5-acetate filaments. After spinning, the individual filaments are combined into a band and then crimped in a stuffer box. The product is then dried, filled into a storage container and finally pressed into bales. Depending on the bale format, these bales weigh between 350 and 650 kg, with exceptionally also high-density bales with weights of up to 900 kg, so-called "high-density tow bales", as are described, for example, in US Pat. No. 4,577,752.

After the filter tow bale has been transported to the filter or cigarette manufacturer, the filter tow is removed from the bale and placed on a filter rod machine, as described e.g. in US-A-5,460,590, processed into filter rods. The filter tow is pulled off the bale, pneumatically spread out to a width of 100mm or more, stretched in a stretching device, provided with an additive which serves to glue the filaments, and then, after formation of a three-dimensional fuse, is introduced into the format part using a pneumatic inlet funnel, there compressed axially, covered with paper and cut to the final length of the filter rods.

The essential quality characteristic for the consumer is the homogeneity of the produced filter rods with regard to the draw resistance, since this influences the smoker's taste sensation and the filter performance. The still acceptable draw resistance variations depend on the absolute value of the draw resistance. In general, with averaging at least 10 samples from each 5 measured filter rods, a variation coefficient of maximum 3.5% is just accepted by the ner worker. As a rule, however, an average of less than 3.2% is aimed for. None of the individual values of the variation coefficients of these at least 10 samples should be higher than 4.5%. The homogeneity of the filter rods with regard to the tensile resistance is influenced by several factors, for example by the quality of the filter tow, by the ner pack and by the ner processing method. As for the ner pack, it is important for the filter tow to run smoothly from the bale. Particularly due to the ever increasing packing density of the bales, there are often fluctuations in tension resistance. While an average of 350 kg / m ^{3 was} common 10 years ago, the packing density of filter tow bales is currently between 450 and 500 kg / m ³ . Process-related work problems often occur with these high-density bales. Voltage changes when the filter tow is removed lead to uneven northward stretching of the material as it enters the filter rod machine and thus to fluctuations in the material and tensile strength.

It is an object of the present invention to provide a highly compressed filter tow bale in which the processing problems mentioned above have been largely eliminated.

This object is achieved according to the invention by a filter tow bale according to claim 1.

The filter tow bale according to the invention with a packing density of more than 450 g / m ³ has an average Shore hardness of less than 50 on its surface, measured perpendicular to the tow position, no local Shore hardness values of more than 60 and the tow width in the bale is less than 50 mm if the tow has a total titer of more than 30,000 dtex, or the tow width in the bale is a maximum of 1.7 * 10 ^"6 (m / dtex) * Total titer (dtex) is when the tow has a total titer of less than 30,000 dtex, the value of the heap factor being more than 20 and the effective placement width being less than 65 mm.

It has been found that the hardness value is an excellent indicator of the trouble-free drainage of the filter material from the bale. Thus, by means of a suitable ner packing strategy, the tensile resistance scatter of the filter rods produced can be positively be influenced. In addition to a uniform ripple of the filter tow, which is however already determined by the manufacturing process, the subsequent processing steps can be considerably simplified and faults minimized by optimizing the tow storage. It is consequently also important to ensure that the average hardness remains below the stated value even in the case of highly compacted bales with a packing density of more than 450 g / m ³ . The mean hardness of a bale is understood to mean the mean value that results from 10 times 9 different measurements at the points on the surface of the filter tow bale identified in measurement scheme 1: The hardness of the bale is compared with that in DIN 53505, Edition 2000 - 08 (testing of rubber and elatoms according to Shore A and D) determined using the Shore A method.

In general, the adhesion from band to band or also the adhesion from fiber to fiber increases with increasing bale density, which has negative consequences for the product uniformity with regard to tensile resistance achieved during processing. It is therefore important to ensure that, despite the increasing tape adhesion, the average hardness of the bales remains within the scope specified according to the invention. As has been found in various measurements within the scope of the present invention, the risk of increased scatter of resistance in the end product, i.e. in the finished filter rod, increasing significantly with increasing hardness. These measurements have shown that there is considerable scatter of tensile resistance in the processing of individual samples as soon as the average hardness exceeds the critical value of 50. In individual samples, variation coefficients with respect to the average train resistance of significantly more than 4.5% were found even if the mean value of the variation coefficients from 10 samples was still within the tolerable range of less than 3.5%.

In order to avoid the occurrence of locally increased hardness values, care should be taken when packaging the filter tow bale that severe constrictions are avoided when using tapes. However, the correct packaging of the filter tow bales is not the subject of this invention. Possible solutions to the packaging problem include US-A-5 77 752 and in particular in G 7635849.1, a packaging without tapes being specified in the last-mentioned publication.

In order to achieve the low hardness values according to the invention, it is important to keep the ratio of the unpressed volume of a filter tow bale and the pressed volume as low as possible. The unpressed volume is understood to be the volume that arises from the pre-compression due to gravity or a targeted mechanical pre-compression of the filter tow in the filling can. The unpressed volume of a filter tow bale can be calculated using the following formula:

Vu = L x B _B x A x HL

where L is the length of the bale, B _{B is} the width of the bale, A is the number of layers and H _{L is} the height of a layer.

Investigations have shown that bales with a filling density of more than 450 kg / m ³ can no longer be processed without problems if the ratio of the unpressed volume Vu and the pressed volume Vp was greater than 3.5. A very high average hardness was measured with such bales and in particular greatly increased individual values were found. The average hardness, measured at the top of the bale surface, was more than 50, with individual values of over 60 also available. The filter rods produced had tensile resistance scatterings which were above the desired values specified above.

When producing the bales according to the invention, which have a packing density of more than 450 kg / m ³ , care must be taken to ensure that the ratio of the unpressed volume Vu to the pressed volume Vp is significantly smaller than the above-mentioned value of 3.5. In order to achieve bale hardnesses that are less than 50 on average, with no individual hardness values greater than 55, a ratio of Vu to Vp of less than 3.2 should be aimed for. In the context of the present invention, particularly those filter tow bales are preferred whose average shore hardness is the surface of the bale is less than 45, preferably no local hardness values of more than 55 should occur. This is generally accomplished by further reducing the Vu to Vp ratio, particularly to a value less than 3.1.

The ratio of unpressed volume to pressed volume is dependent on a number of factors that affect each other. Of these factors, the bandwidth plays in particular, i.e. the width of the filter tow band in the bale, and the so-called accumulation factor play a role.

It has been found that the unpressed volume Vu of the filter tow bale (and thus also the volume ratio of the unpressed and pressed filter tow bale) can be reduced by suitably arranging the filter tow within the bale. As already indicated above, the unpressed volume can be reduced by reducing the mean width of the filter tow in the bale. According to the invention, maximum limits for the values of the average width were determined as a function of the overall titer. Accordingly, the tow width in the bale must be less than 50 mm if the tow has a total titer of more than 30,000 dtex, or a maximum of 1.7 x 10 ^"6 (m / dtex) x total titer (dtex) if the Tow has a total titer of less than 30,000 dtex, and adhering to the above-mentioned values ensures a smooth removal of the filter tow from the bale in a subsequent processing process and low fluctuations in tensile resistance in the end product proven less than 45 mm if the total titer of the filter tow is greater than 30,000 dtex or tow widths of less than 1.5 x 10 ^"6 (m / dtex) x total titer (dtex) if the total titer is less than 30,000 dtex.

The teaching according to the invention, according to which a slight fluctuation in the tensile resistance can be achieved by keeping the width in the filter tow in the bale below a certain limit, is diametrically opposed to that previously prevailing among experts in the field of the manufacture and processing of filter tow Opinion that narrow filter tow often as a serious quality defect is seen. Problems often arise with tow bales of smaller width in the pneumatic spreading during the further processing of the filter tow to filter rods and consequently in width fluctuations during the spreading process in the filter rod machine. As a result, there are again fluctuations in the tensile resistance that are above the quality limits mentioned in the introduction. However, it was found within the scope of the invention that these difficulties are mainly due to the fact that a reduction in the absolute width of the filter tow band is often accompanied by an increase in the relative width variation. It is this increased relative latitude variation that is primarily responsible for the latitude variations during the spreading process on the filter rod machine. It could be shown that by reducing the mean width overall, a reduction in the tensile resistance scatter of the finished filter tow rod can be achieved if it is ensured that the width fluctuations of the tow in the bale are less than ± 12% of the mean width of a filter tow. Filters Tows whose fluctuation range is less than ± 10% are particularly preferred.

The desirable fluctuation ranges mentioned are below those which are usually accepted for filter tow, as can be seen from the table below. It specifies the maximum permissible tolerance values depending on the mean width and the total titer of the filter tow according to the prior art.

The tow widths mentioned in the table are common because they have proven to be optimal both in the packaging of the bales and in the processing of the material on some filter rod machines. For the specifications mainly used today A width of approximately 52 mm is usually specified (cf. Celanese acetate, RodMap ™ KDF2 / AF2, version 2.0, 1995). The width of the tow is an easy-to-check size for the processor.

As is known to the person skilled in the art, the width of a filter tow, which is of course dependent on filament and total titer, can be influenced by a variety of measures in the production process. Here are the width of the belt guide, the moisture of the filter tow when entering the crimping machine, the roller width of the crimping machine, the geometry of the stuffer box and the way in which the filter tow is mechanically loaded during and after drying up to insertion , Filter Tow, which despite the reduced width does not have greater width fluctuations than ± 12%, can be generated, for example, by the tape in the stuffer box or after leaving the stuffer box crimp and before entering the dryer with at least 20 g of water (resp. Water vapor) is rewetted per kg filter tow. With this measure, in addition to the reduction in the scattering in the resistance to drag, the formation of lint, which is troublesome during further processing, can be significantly reduced.

Depending on the total titer, a value of approximately 0.7 * 10 ^"6 (m / dtex) * total titer (dtex) is to be regarded as the absolute lower limit of the width, which is possible or sensible from a process engineering point of view by reducing the unpressed volume, the advantage achieved with regard to the scattering in the resistance to drag due to the procedural problems that arise during the further processing of the filter tow already below an average width of 0.8 * 10 ^"6 (m / dtex) * total titer (dtex), so that from this value onwards no further increases in quality can be achieved by further reducing the width.

In addition to a reduction in the bandwidth, a favorable ratio of the unpressed to the pressed volume can also be achieved by the clustering factor already mentioned above. The so-called accumulation factor H is an important variable that describes the placement of the tape in the bale. It describes the ratio of the length of the completely crimped filter tow of a layer to the length of the layer. H = L ₀ / L _A = 10,000 xm _A (g) / total titer (g / m) / L _A (m),

where m _{A is} the weight of a layer of filter tow in the bale, L _{A is} the length of a layer of filter tow in the bale (this corresponds to the length of the bale) and Lo is the length of a completely uncrimped layer of filter tow. The higher the accumulation factor, the lower the take-off speed of the tape directly from the bale and thus the disturbance in the tape-to-tape separation. If the values are too high, however, the filter tows that are common today result in the belt being overthrown, which can ultimately lead to tape breaks when processed on the filter rod machine. The disturbance called whip effect, which arises at the reversal points due to the reversal of the direction of the belt, is also significantly influenced by the accumulation factor. Low values lead to increased difficulties here. A thorough examination of products on the world market has shown that the usual values for the clustering factor are between approximately 11 and 22. Values up to around 30 occur, but are the exception.

Investigations within the scope of the present invention, however, have shown that, in order to achieve the lowest possible fluctuations in train resistance, it is preferable to use frequency factors whose values are well above those which have been customary to date. It has been found that optimum tensile resistance values are achieved when the value of the stacking factor is above approximately 20 and below approximately 35. Piling factors of more than about 25 and in particular more than about 30 are particularly preferred within the scope of the invention. Within the ranges mentioned, the filter tow is pulled off the bale smoothly, the occurrence of the whip effect being largely avoided. However, stacking factor values greater than about 35 are to be avoided due to the frequent occurrence of tape overhangs.

In particular, the accumulation factor should be selected so that an effective placement width of the filter tow of 65 mm is not exceeded. To minimize the unpressed volume, an effective placement width of less than 65 is preferred mm and in particular less than 60 mm. The value of the effective placement width depends on the bandwidth of the filter tow band and the accumulation factor. It is calculated using the following equation:

Beff = W x (l + H 100),

where B _{eff is} the effective spreading width.

Another characteristic variable of a filter tow bale is the so-called placement frequency F. This is the number of longitudinal strokes of the placement per cross stroke. A complete layer of filter tow with F traces has the following total weight:

M = F xm _A = F x H x total titer (g / m) x L _A (m) / l 0.000,

where m is the mass of a deposit track and L _{A is} the length of a deposit track.

The laying frequency F is determined independently of the laying pattern in such a way that a flat surface that is as uniform as possible is produced even in the unpressed state. It has been found that optimum placement is achieved when the product of the laying frequency F and the effective laying width B _er r of a band is approximately equal to the width of a bale. This is illustrated by the following relation:

F x B _eff = width of the filter tow bale

It was determined from empirical tests that the average height of a layer of unpressed filter tow tends towards the value of approximately 10 mm as soon as more than approximately 500 kg are filled into a press jug and the relation given above is observed. In this way, an optimal layering of the filter tow in the bale is achieved, with the result that the removal of the filter tow from the bale in the course of further processing to filter rods runs smoothly, ie without interference, so that the generated filter rods can achieve excellent values with regard to the scattering of the resistance.

The invention is explained in more detail below using two exemplary embodiments.

Comparative example:

A filter tow band with a filament titer of 3.3 dtex and a total titer of 38500 dtex is spun. The filament cross section is Y-shaped. The tape is crimped using a conventional stuffer box process. After passing through the dryer, the tape with a moisture content of 5.0%) is placed in a teapot with a base area of Lo x B _B = 1200 mm x 1000 mm. When placed in the jug, the filter tow has a width of 62 mm + - 9mm. The packing machine for filling in the material is set so that there is an accumulation factor of 20 and a depositing frequency F of 13. After filling a total of 605 kg of filter tow, an unpressed volume Vu of 4.2 m ³ results. The filter tow is pressed to a final volume of 1.2 m ³ and packed as usual.

After a storage period of one week, the bale is opened to firstly determine the surface hardness and, secondly, to produce filter rods for determining the spreading resistance. In addition, the width of the filter tow is measured during the process.

The measurement of the Shore hardness, measured on the surface of the bale, gives an average of 58 with a standard deviation of 10.55. The largest value was determined at 71 and the smallest value at 43.

With this bale, filter rods with a length of 126 mm and a diameter of 7.8 mm are produced on a filter rod machine KDF2 / AF2 at a processing speed of 400 m min. The target tension resistance was 350 daPa. A coefficient of variation of 3.5% was determined from 10 samples of 5 measured filter rods each, the maximum value being 5.2%. The width of the filter tow was determined as follows: The filter tow is drawn off on a filter rod machine KDF2 / AF2 at a speed of 100 m / min. The air is switched off at the first spreader nozzle. A line camera for measuring the tow width is attached 300 mm below the spreader nozzle. The evaluation of 100 individual measurements (one measurement every 3 seconds) resulted in an average tow width of 66.3 mm, the smallest individual value being 48 mm and the largest 81 mm.

Example 1:

A filter tow band with a filament titer of 3.3 dtex and a total titer of 38500 dtex is spun. The filament cross section is Y-shaped. The tape is crimped using a conventional stuffer box process. After the crimping process, the filter tow is moistened with 10g water per kg tow.

After passing through the dryer, the belt with a moisture content of 5.5% is placed in a jug with a base of Lo x B _B = 1200 mm x 1000 mm. When placed in the jug, the filter tow has a width of 45 mm + - 4mm. The packing machine for filling the material is set so that there is an accumulation factor of 32 and a placement frequency F of 17. After filling in a total of 605 kg of filter tow, an unpressed volume Vu of 3.606 m ³ results. The filter tow is pressed to a final volume of 1.2 m ³ and packed as usual.

After a storage period of one week, the bale is opened to firstly determine the surface hardness and secondly to produce filter rods for determining the scattering in the resistance. In addition, the width of the filter tow is measured during the process.

The measurement of the Shore hardness, measured on the surface of the bale, gives an average of 43 with a standard deviation of 3.41. The largest value was determined at 52 and the smallest value at 39. With this bale, filter rods with a length of 126 mm and a diameter of 7.8 mm are produced on a filter rod machine KDF2 / AF2 at a processing speed of 400 m / min. The target tension resistance was 350 daPa. A coefficient of variation of was determined from 10 samples of 5 measured filter rods each

2.5% determined, the maximum value being 3.4%.

The width of the filter tow was determined as follows: The filter tow is drawn off on a filter rod machine KDF2 / AF2 at a speed of 100 m / min. The air is switched off at the first spreader nozzle. A line camera for measuring the tow width is attached 300 mm below the spreader nozzle. The evaluation of 100 individual measurements (one measurement every 3 seconds) resulted in an average tow width of 49.1 mm, the smallest individual value being 40 mm and the largest one being 51 mm.

Example 2:

A filter tow band with a filament titer of 3.3 dtex and a total titer of 38500 dtex is spun. The filament cross section is Y-shaped. The tape is crimped using a conventional stuffer box process. The filter tow is moistened with 8g water per kg tow immediately before the crimping process and with 5g water per kg tow after the crimping process.

After passing through the dryer, the strip with a moisture of 6.1%) is placed in a teapot with a base area of Lo x B _B = 1200 mm x 1000 mm. When placed in the jug, the filter tow has a width of 35 mm + - 4mm. The packing machine for filling the material is set so that there is an accumulation factor of 32 and a placement frequency F of 19. After filling in a total of 605 kg of filter tow, an unpressed volume Vu of 3.42 m ³ results. The filter tow is pressed to a final volume of 1.2 m and packaged as usual. After a storage period of one week, the bale is opened to firstly determine the surface hardness and secondly to produce filter rods for determining the scattering in the resistance. In addition, the width of the filter tow is measured during the process.

The measurement of the Shore hardness, measured on the surface of the bale, gives an average of 41 with a standard deviation of 3.11. The largest value was determined at 46 and the smallest value at 37.

With this bale, filter rods with a length of 126 mm and a diameter of 7.8 mm are produced on a filter rod machine KDF2 / AF2 at a processing speed of 400 m / min. The target tension resistance was 350 daPa. A coefficient of variation of 2.0% was determined from 10 samples of 5 measured filter rods each, the maximum value being 2.7%.

The width of the filter tow was determined as follows: The filter tow is drawn off on a filter rod machine KDF2 / AF2 at a speed of 100 m / min. The air is switched off at the first spreader nozzle. A line camera for measuring the tow width is attached 300 mm below the spreader nozzle. The evaluation of 100 individual measurements (one measurement every 3 seconds) resulted in an average tow width of 40.1 mm, the smallest individual value being 38 mm and the largest being 42.5 mm.

1 shows a schematic view of a bale surface with possible measuring points 1 to 9. Each of the dimensions is approximately 100 mm x 100 mm. The individual results measured at the various measuring points are inserted into the table below during the tests, and the mean value and the maximum value are then determined.

* * *

Claims

claims

1. Filter tow bales with a packing density of more than 450 kg / m ³ , characterized in that the bale on its surface, measured perpendicular to the tow position, has an average Shore hardness of less than 50, that no local Shore hardness values of more than 60 and the tow width in the bale is less than 50 mm if the tow has a total titer of more than 30,000 dtex, or the tow width in the bale is a maximum of 1.7 * 10 ^"6 (m / dtex ) * Total titer (dtex), if the tow has a total titer of less than 30,000 dtex, the value of the heap factor is more than 20 and the effective placement width is less than 65 mm.

2. Filter Tow bale according to claim 1, characterized in that the bale on its surface, measured perpendicular to the tow position, has an average shore hardness of less than 45.

3. Filter Tow bale according to claim 1 or 2, characterized in that the bale has no local hardness values of more than 55.

4. Filter Tow bale according to at least one of the preceding claims, characterized in that the tow width in the bale is less than 45 mm when the

Total titer of the filter tow is greater than 30,000 dtex and that the tow width is less than 1.5 * 10 ^"6 (m / dtex) * total titer (dtex) if the total titer is less than 30,000 dtex.

5. Filter Tow bale according to at least one of the preceding claims, characterized in that the value of the stacking factor is between 23 and 35.

6. Filter Tow bale according to claim 5, characterized in that the value of the stacking factor is between 25 and 33.

7. Filter Tow bale according to claim 6, characterized in that the effective placement width is less than 60 mm.

* * *