FI56310C - FILTER ELEMENT - Google Patents

Description

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Patent * and National Board of Registration (44) Date of publication of NihUvikriptnon et al. -

Patent · och registrstyrelsen 'AnsBkan utlsgd och utl.skrtftsn publicksd 28.09.79 (32) (33) (31) privilege ,

Millbank, London SW1, England-England (GB) (72) James Rodney Hammersmith, Jeffersonville, Indiana, Philip Hancock Cogbill II, Louisville, Kentucky, USA (US) (74) Oy Heinänen Ab ($ 4) Filter Element - Filter Element of this Invention the object is a filter element, in particular for cigarettes, comprising a relatively rigid tubular sleeve of tobacco smoke-impermeable material inside which the filter material is placed and at least one axial channel, the walls of which are insulated from the filter material and the other end of which is in direct contact with the tobacco element the other end being spaced from the end opposite the tobacco portion of the filter element.

In recent years, efforts have been made to use filter materials with even greater efficiency, especially in cigarettes. Efficacy in this case refers to the total amount of a substance that is removed from the smoke produced by smoking tobacco before it enters the smoker's mouth.

Although increased efficiency is generally considered desirable when a smokeless tobacco product is first smoked, the smoker generally does not experience the feel or effect of tobacco smoke when using said high efficiency filters. In addition, the effect of the entire tobacco rod increases the efficiency of the filter. The combined effect of the filter and the tobacco rod is then such that almost all the fines are removed from the smoke, as a result of which the tobacco smoker does not get satisfaction from these first stews. f.,; As an aspect not related to this drawback, U.S. Pat. No. 3,270,750 proposes the provision of channels in a filter for a smokeable cigarette. The publication presents various locations and shapes for the channels, where the channel extends over the entire length of the filter. However, it should be noted that whatever the location or shape of such a channel, it closes before the cigarette is burned out due to the pressure exerted by the fingers. The filter is then designed precisely in such a way that it can be decomposed.

U.S. Pat. No. 3,752,165 discloses a filter with a cavity which forms a bypass for the smoke past the actual filter portion. Extensive porous areas are formed in the walls of the cavities to allow smoke to pass through, and the purpose of the cavities is to reduce the amount of filter material required for the filter and to allow the smoke to flow in a direction transverse to the longitudinal axis of the filter. Thus, even this filter does not provide a solution to the above-mentioned drawback of current high-performance filters.

The object of the present invention is to provide a filter element in which, by means of axial channels known per se, it is provided that the amount of fines passing through the filter remains relatively constant throughout the smoking of the cigarette. The invention is characterized in that the end opposite the tobacco part of the channel has a nozzle-like opening leading to the inside of the sleeve, which is substantially narrower than the inner diameter of the channel, said end of the channel being otherwise closed.

When using the filter element according to the invention, in the initial stage of smoking a cigarette, at least a part of the smoke generated when smoking a cigarette passes through the channel and the nozzle-like opening and then further through the rest of the filter. The walls of the duct, with the exception of the nozzle opening, are substantially impermeable to smoke, as a result of which no filtration takes place through these walls. During cigarette smoking, the portion of the cross-section of the filter that is close to the nozzle orifice gradually becomes clogged due to the accumulation of solids. As the clogging progresses, the flow resistance of the smoke passing through this point of the filter increases, as a result of which gradually all or substantially all of the smoke generated when the cigarette is burned passes directly through the main body of the filter. As a result, the fines in the smoke are generally evenly distributed throughout the filter.

3,563 \ v

Even if a very efficient filter is used, due to the short distance traveled by the smoke in the filter material, a full feeling of cigarette burning is achieved already during the first few puffs. It is known that when a cigarette is smoked, the first smoke flavor contains relatively little solids in all cases. This is mainly due to the filtering effect of the tobacco rod, as a result of which the full filtration power of the filter body is not required in all cases.

In order to illustrate the invention, some embodiments thereof will be described below with reference to the accompanying drawings, in which

Figure 1 is a perspective view of a so-called a programmed filter with a single channel at the edge.

Figure 2 is a side view of the filter of Figure 1 as part of a cigarette.

Figure 3 shows a side view of a filter according to the invention with two channels of different lengths.

Figure 4 shows a side view of a filter according to the invention with two channels of equal length.

Figure 5 shows a side view of a filter according to the invention, the channel at the edge of which is formed to taper.

Fig. 6 is a diagram showing the amount of all the fine material leaving per suction on the other hand, the so-called programmed on the one hand and the so-called to an unprogrammed filter.

Fig. 7 is a diagram showing the calculated efficiency per suction in a programmed and non-programmed filter.

Fig. Θ is a graph showing the total amount of fines from a cigarette as a function of nozzle orifice.

Figure 1 shows a filter element, indicated by the reference number 1. The element contains a highly effective filter material 2 located in a rigid plastic sleeve 3 in which a channel 4 is formed. A nozzle-like opening 5 is formed at the end of the channel. Fig. 4 56310 2 shows the filter element 1 according to Fig. 1 placed in a cigarette having a tobacco-containing part 6 and a wrapper 7 surrounding both the tobacco part and the filter 1. It can be seen from Fig. 2 that the open end Θ of the channel 4 is close to the tobacco part up to the mouth end 9 of the tobacco product to be smoked.

According to Figure 3, the filter element 11 is connected to a smokable tobacco product comprising a tobacco-containing part 16, in which both the tobacco part and the element are surrounded by a wrapper 17. The filter 11 of Figure 3 has an elongate channel 12 with an open end 13 connected to the tobacco part 16. 14. A shorter channel 18 is also formed in the filter, the open end 19 of which is connected to the tobacco part. An opening 20 is formed in the other end of the channel 18. Also in this case, the channels terminate close to the end to be placed in the mouth of the cigarette.

Figure 4 shows a filter element 21 which differs from the element 11 in that the channels 22, 22 'are of the same length. The element is connected via the wrapper 27 of the tobacco part 26. Both channels 22 and 22 'of the element 21 are connected at their open ends 23 and 23' to the tobacco part, while the opposite ends are provided with nozzle openings 24 and 24:

In Figure 5, the filter element 31 is likewise connected to the tobacco part 36, and both parts are wrapped in a wrapper 37. The filter 31 has a single channel 32 which differs from the above-mentioned channels due to its tapered shape. The widest portion 33 of the channel is open and engages the tobacco portion 36. The channel gradually tapers toward the nozzle opening 34 formed at the opposite end of the channel. Also in this case, the channel terminates near the mouth end of the cigarette.

It should be noted that the filter elements shown in the figures have not necessarily been drawn using actual dimensions, as they are only intended to illustrate various practical embodiments of the present invention. In general, the channel lengths are approximately 80% of the total length of the filter. The lengths of the duct or ducts should usually be 50-85% of the length of the filter. In all the cases shown, the channels and nozzles are drawn larger than what they can usually actually be made to make the patterns clearer. The numerical values for their lengths and diameters are presented in more detail below.

5,56310

Several factors play an important role in designing a usable filter as described above. The overall efficiency of this type of filter is largely determined by the type of filter selected as the filter body. Such usually important parameters are the type of fiber, the weight of the filter rod, its circumference and the distribution of the fibers therein.

In the so-called in the programmed filter are important additional factors at the end of the entire nozzle orifice, the non-porous walls delimiting the duct, and the ratio of the smoke flow resistances at the start of combustion between the duct and the nozzle flow and the main body of the filter element. The shape and location of the nozzle opening, the degree of compression of the filter material, the dimensions of the groove and the position of the fibers in the main filter element are also important, especially near the end of the filter.

In a programmed filter, this initial resistance ratio is determined by the pressure drop of the main filter divided by the pressure drop of the nozzle orifice and the shorter flow path formed by the end of the filter. Independently of these, these values have been obtained using an air flow of 17.5 cm / s. The percentages of the original smoke flavors passing through the duct and the orifice compared to the smoke flow through the main filter are shown in the following Table 1 with varying resistance:

table 1

Initial resistance to smoke flow__

Volume percentages of smoke flavorings as smoke passes_

Ratio Through duct and nozzle orifice Through main filter 0.1 10 90 0.5 33 67 1.0 50 50 3.0 75 25 5.0 B3 17 6 .56310

In general, regardless of the main filter element used, a minimum initial efficiency and a minimum efficiency increase ratio in subsequent smoke flavors are obtained as a programmed filter with the highest possible resistance ratio. In the filters of this invention, the desired initial resistance ratios are in the range of 0.5-5.0, preferably 1.0-3.0. When the initial resistance ratio is less than 0.5, no programming effect is produced. When the resistance ratio is greater than 5.0, there are disadvantages that the filter opening must be too large to be effectively clogged after the first smoke flavors, or that the points of clogging are broken down by subsequent smoke flavors. In the preferred range 1 ~ 3, the initial resistance in the flow through the channel and the nozzle orifice is, of course, equal to or less than the resistance in the main filter section. As a result, under the effect of the first smoke flavors, 50-75% of the smoke passes through the path with the lowest resistance, i.e. through the channel to the nozzle. As the path of this smoke gradually becomes blocked, an ever-increasing portion of the smoke begins to pass through the main body of the filter. Generally, during the fourth or fifth smoke smoke, the resistance in the path of the channel nozzle orifice is greater than the resistance in the main filter, as a result of which most of the smoke then passes through the main filter. Usually, due to the last smoke taste, the nozzle orifice is almost completely blocked and substantially all of the smoke passes through the main filter.

This programming effect can be seen in Figures 6 and 7. Figure 6 shows the retention of all the material to be filtered per suction in a standard quality cellulose acetate filter and a programmed filter according to the present invention. It can be seen that the amount of milligrams generated per aspiration is substantially the same from the first to the ninth aspiration using a programmed filter, while the standard cellulose acetate filter absorbs more than twice the amount of filtrate per aspiration in this range of aspirations. This pattern of tar evolution per aspiration can be seen in Figure 7, which shows the efficiency of the filter for each stroke. In this case, the efficiency of a standard quality cellulose acetate filter changes very little between the first and ninth puffs, while the efficiency of the programmed filter increases from about 40% to about Π0% between cigarette burns.

The best possible size of the nozzle opening formed at the end of the channel when using a single channel is 12-30 Birmingham units. Most preferably, the nozzle orifice size of such a filter is 12-21 Birmingham 7,56310 units. The size of the channel leading to the opening is such that it has a diameter of 1 to 3 millimeters and is generally slightly larger than the nozzle.

When the size of a channel is pronounced as its diameter, it is a question of the cross-section of the channel and not its shape or diameter, which are the critical factors.

The cross-sectional area of the duct must not be too large so as not to create a risk that the cross-sectional area of the main filter element becomes too small, since the part of the main filter corresponding to the duct is then left out. The length of the channel is not critical and is chosen such that the relative resistance between the main part of the filter medium and the channel, the nozzle opening and the short part of the filter medium is within the limits described above.

A certain filtration density is necessary for the substance to be filtered to adhere to the filter medium between the nozzle opening and the filter head. The appropriate speed required for this purpose is achieved by coating the channel as mentioned above.

When more than one channel and nozzle are used, as shown, for example, in Figures 3 and 4, the total cross-sectional area of the nozzle orifices must be slightly larger than the cross-sectional area of a single nozzle orifice in order to obtain the same result. Since the substance to be removed by filtration forms a substantially hemispherical part in the filter medium at the nozzle opening, more filterable substance is needed to block one nozzle opening than several nozzle openings with the same cross-section. Thus, if the cross-sectional size of multiple orifices increases relative to a single orifice such that substantially the same amount of material to be filtered is required to occlude more orifices than is required for a single orifice, this results in substantially the same amount of filtrate being required to block more orifices than would be required. for the nozzle opening when using the same type of programming.

When there are several nozzle openings, as shown in Figure 3, for example, where the channels are different in length, one channel, for example channel 12, may be the channel through which smoke flows during the first puffs when smoking a cigarette, after which the smoke flow may pass to another channel such as channel 16. and finally to the main body of the filter media. Although only two channels are shown in Figure 3, their number may, of course, be different.

The effect of the nozzle orifice size variation within the above limits is \.

a shown in Fig. B. When the same filter medium is used in different cases, the amount of all the substance to be removed by filtration per aspiration varies with the sequence number of the aspirations varying from 1 to 9. It can be seen that as the nozzle orifice size becomes smaller, a larger amount of filtrate per suction is removed while other factors remain unchanged. Also in this case, the level of removal of the filter material is easily observed compared to the reference cigarette.

If desired, a single channel associated with more than one of the embodiments shown in the figures, or one or more channels in the embodiments of Figures 3 and 4, may be filled or partially filled with a substance that provides a particular and desired effect. For example, flavoring agents can be placed in the duct to scent the first puffs of smoke. When such a substance is placed in a duct, it must be of the type and used in such a quantity that the programming effect of the filter is not lost.

The main filter element, for example 2 in Figure 1, can be made of different filter materials. It can be made, for example, from paper or cellulose acetate. It is generally selected in consideration of its filtration efficiency, and when using a filter according to the present invention, the filtration efficiency relative to the smoke remover should be at least about 50%.

As shown in Fig. 1, the main filter is surrounded by a plastic shell, in which case a channel is formed in this shell, and a nozzle opening is formed in the end of the channel through the shell. The function of the plastic shell is twofold: 1. It prevents the filter from crushing, which could result in the channel breaking 2. It keeps the walls of the channel impermeable so that no filtration takes place through these walls. The plastic shell is not a critical point in the present invention as long as its two types of operation can take place. Thus, for example, after the channel has been formed in the filter medium, the periphery of the filter material can be covered so as to create the necessary impermeable surface, thereby increasing the mechanical strength. Depending on the filter material used in each case, heat sealing can also be used.

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The effects of the various parameters mentioned above on the operation of the programmed filter are illustrated in Table 2. It shows the different parameters and the effects of these parameters on the different variables including initial filter pressure drop, initial filter efficiency, initial duct and nozzle flow rate, final filter pressure drop and final filter pressure. efficiency. The increases and decreases for all these measurable quantities are indicated by the notation and the non-change is marked as '0'.

In order to provide those skilled in the art with a more illustrative understanding of the present invention, a few examples of embodiments of the invention are set forth below.

Examples 1-3 In these examples, filter elements made of cellulose acetate with a denier of 1.6 per fiber and a denier of 24,000 per filter and secondary corrugation were used. 3 filters were made of said material so that their nozzle orifice sizes were 19, 17 and 15 Stubs dimensions, i.e. diameters of 1.1, 1.5 and 1.8 millimeters, respectively. The total amount of substance to be removed in milligrams per cigarette, the initial pressure drops in millimeters of water column, the initial relative resistances and the filter efficiencies are shown in Table 3.

It can be seen that in each of these filters there was a significant increase in the efficiency of the filter from the first suction to the last suction.

Example 4 In this example, the cellulose acetate filter had a denier of 1.6 per fiber and a total denier of 48,000. The diameter of the nozzle was 1.8 millimeters and the Stubs dimension 15. The total amount of material removed from the smoke was 12.2 milligrams per cigarette and the initial pressure drop was 94 millimeters from the water column. The initial resistance ratio was 0.9. The filter efficiency of the cigarette was 50% overall, including an initial efficiency of 34% and a final efficiency of 65%.

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Example 5 In this example, a cellulose acetate filter element having a fiber denier of 2.5 and a total filter denier of 44,000 was used. The nozzle orifice was 1.8 millimeters in diameter and the Stubs dimension was 15. The total amount of material removed from the cigarette was 17.6 milligrams. The initial pressure drop was 55 millimeters of water column and the initial resistance ratio was 1.4. The overall efficiency of the cigarettes was 31% including the initial efficiency of 16% and the final efficiency of 47%.

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Claims (4)

13 56 3 1 υ A filter element (1,11,21,31), in particular for cigarettes, comprising a relatively rigid tubular sleeve (3) of tobacco smoke-impermeable material, inside which the filter material (2) is arranged, and at least one axial channel ( 4,12,22,32), the walls of which are insulated from a filter material and one end of which is in direct contact with the tobacco part (6,16,26,36) to be connected to the filter element, the other end being spaced apart from the opposite end (9) of the filter element that at the end opposite the tobacco part (6,16,26,36) of the channel (4,12,22,32) there is a nozzle-like opening (5,14,24,34) leading to the inside of the sleeve (3), which is substantially narrower than the inner diameter of the channel, said end of the channel being otherwise closed. Filter element (1,11,21) according to Claim 1, characterized in that the channel (4, 12, 22) consists of an axial groove on the surface of the sleeve (3). Filter element (11) according to Claim 1 or 2, characterized in that the filter element (11) has a plurality of channels (12, 16) of different lengths. Filter element (31) according to Claim 1 or 2, characterized in that the cross-sectional area of the channel (32) decreases towards the end provided with the nozzle-like opening (34) of the channel.