CN115697097A - Filter for adsorbing health-hazardous tobacco smoke constituents - Google Patents

Abstract

The invention relates to a filter for absorbing components of tobacco smoke harmful to health, the filter having ceramic particles bonded in a porous structure (12). In order to prevent contamination of the filter for a short period of time even if it is not properly treated, without loss of adsorption performance and smoking experience, it is proposed that the filter has an opening from the tobacco side section (1) towards the opposite mouth Reduced water solubility of the side sections (2).

Description

Filters for absorbing components of tobacco smoke harmful to health

technical field

The present invention relates to a filter for absorbing components of tobacco smoke harmful to health, the filter having ceramic particles bonded in a porous structure.

Background technique

Cigarette filters are used to remove substances harmful to health from tobacco smoke. Traditional filters consist of cellulose acetate, a plastic that is difficult to biodegrade. This has the disadvantage that improperly disposed of cigarette butts can cause considerable environmental pollution and animals may be harmed from the cigarette butts if eaten.

To circumvent this, alternative materials for filters have been developed. No. 2,996,067 discloses a filter for adsorbing substances harmful to health which consists of ceramic particles bonded in a porous structure. Although ceramic particles are essentially naturally occurring inorganic substances that are not problematic compared to various types of plastic, there is still the problem that such filters can lead to contamination if not disposed of properly.

Thus, filters made of hemp and eg cotton are known from US2996067. Although such filters are biodegradable, this biodegradation process takes several days to complete degradation and requires a corresponding environment for the microorganisms responsible for the degradation, which however is not prevalent especially in urban areas.

Other filters with ceramic particles are known from EP0539191A1, EP0766929A2, US3428054A and GB1243358A. Filters comprising ceramic particles bonded into a porous structure are disclosed in GB1005786A and EP0539191A1. EP1504682A1 and KR200476478Y1 show traditional cigarette filter manufacturing methods.

Contents of the invention

The technical problem to be solved by the present invention is therefore to propose a filter of the type mentioned at the outset, which avoids contamination even if it is not properly disposed of within a short period of time, without compromising adsorption properties and smoking Loss of feeling.

The invention solves this technical problem in that the filter has a water solubility that decreases from the tobacco-side section towards the opposite mouth-side section. As a result of this measure, the filter dissolves when it comes into contact with large quantities of water, for example rainwater. As the water solubility decreases towards the mouth section of the filter, an undesired dissolution of the filter during contact with saliva during smoking is avoided, whereby the filter retains its adsorption capacity over the entire filter length during smoking. For example, it can be provided that the mouth section is only poorly soluble or insoluble in water. Changes in water solubility can be performed segment by segment or continuously. The mouth section can here comprise the filter end which is surrounded by the smoker's mouth. The tobacco side section may comprise a filter end adjacent to the tobacco of the cigarette.

In order to be able to set the desired water solubility of the filter without complex manufacturing processes, it is proposed that the ceramic particles be bonded with a water-soluble binder whose mass fraction is obtained from the tobacco-side section of the filter Increasing towards the opposite mouth section. When in contact with a large amount of water, the binder dissolves, and the insoluble ceramic particles are carried away by the water as suspended solids or precipitated as non-toxic inorganic substances. In principle, a reduction in the water solubility can be achieved with an increase in the mass fraction of the binder, so that on contact with a large quantity of water the sections of the filter which have a lower mass fraction of the binder dissolve first. For example starch can be used as water-soluble binder.

In this case, particularly simple production conditions are obtained with sufficient differentiation of the water solubility of the filter if the filter comprises at least three sections with mutually different and respectively constant binder fractions. This means that an essentially constant adhesive fraction is provided within a section. The mouth-side section here has the largest binder fraction, and the tobacco-side section has the lowest binder fraction. The adhesive proportion of the middle section lies between the adhesive proportions of the other two sections.

In order for the filter to degrade completely in a small shower and still resist a large amount of saliva during smoking, the binder content in the tobacco side section can be in the range of 1-2% by weight, at least one It is in the range of 2-3% by weight in the middle section and in the range of 3-4% by weight in the mouth side section. With this composition, the filter does not dissolve even if it is smoked for a particularly long time. However, the adhesive dissolves quickly if it comes into contact with a greater volume of water. With this composition, a filter according to the invention having the size of a conventional cigarette filter requires approximately 20 seconds to dissolve completely in a cup filled with water equipped with a stirring bar set at 150 revolutions per minute.

In order for the noxious substances to be firmly bound by the filter without thereby negatively affecting the degradability of the filter and the smoking sensation, it is proposed that the porosity of the filter be from the tobacco side section towards the opposite mouth side section Increase. Due to the lower porosity of the filter in the tobacco side section, there is a greater effective surface area for binding toxic substances. The farther the tobacco smoke flows in the direction of the mouth side section, the less toxic the tobacco smoke will be due to adsorption at the tobacco side section, so that porosity can be beneficial for a low resistance attraction of the smoker or for reducing effective surface area without exposing the smoker to the risk of excessive toxic substances. In addition, the greater porosity and thus lower stability of the mouth-side section of the filter with lower water solubility has the positive effect that it can be comminuted in a simple manner, for example by applying pressure, thereby making more The mouth side section which is poorly soluble in water can also be dissolved without residue. However, due to the porous structure of the filter, not only the desired binding of substances harmful to health can take place, but also the water required for the degradation can penetrate, thereby accelerating the degradation process. Porosity is understood as the ratio of the void volume to the total volume of the filter.

In order to be able to set the porosity with the same accuracy in the same process step as water-soluble, in a particularly easy-to-manufacture embodiment of the device according to the invention it is proposed that the filter has at least three different and respectively constant porosity section. In this case, the tobacco-side section has the lowest porosity and the mouth-side section has the highest porosity. The porosity of the middle section lies between the porosities of the other two sections.

It has been found that if the porosity is in the range of 35-50% in the tobacco side section, 50-65% in the middle section and 65-80% in the mouth section, The filter according to the invention then achieves similar properties with regard to the adsorption of unhealthy substances from tobacco smoke and with regard to smoking sensation. The suggested porosity in the range of 35-50% in the tobacco side section provides sufficient effective surface area to bind also high concentrations of health-harming substances in the filter. A porosity in the range of 65-80% in the mouth section results in a lower flow resistance for almost completely detoxified tobacco smoke and also enables easy comminution by external force. A porosity in the range of 50-65% in the middle section represents a compromise between effective surface area and low flow resistance.

The filter according to the invention can be produced in the method according to the invention, wherein mutually different mixtures comprising ceramic particles, space-occupying particles and water-soluble binder are successively filled into a mold, after which the mold contents are extruded Pressure and heat break down the space-occupiers and form a porous structure of bonded ceramic particles. The mixtures can differ from one another in terms of their binder fraction, so that the mixture used to form the mouth-side section of the filter has a larger binder fraction than the mixture used to form the tobacco-side section of the filter. The mixtures can also differ in the proportion of the occupying particles or in the size distribution of the occupying particles, so that the mixture used to form the mouth-side section of the filter has a lower density than the mixture used to form the tobacco-side section of the filter after decomposition of the occupying particles. greater porosity. For example, NH ₄ HCO ₃ can be used as occupying particles, which decomposes into NH ₃ , H ₂ O and CO ₂ by heat treatment and releases gas with the formation of a porous structure.

In order to provide the smoker with a good taste when smoking, the elasticity of the filter may decrease inwardly in the radial direction. Since the outer casing of the cigarette filter is more elastic and thus more bendable, a tactile sensation similar to that of conventional cigarette filters can be produced. The elastic radial course can take place continuously, but also in a decentralized manner. Here, particularly simple conditions for improving the tactile sensation are achieved if felted ceramic fibers are provided as the outer filter jacket.

It has been found that mouthfeel can be further positively affected if the porosity of the filter increases radially outward from the filter element to the filter sleeve. Through the low porosity in the filter element, sufficient effective surface area is obtained to bind toxic substances. Through the increased porosity in the direction of the filter sleeve, the state of a conventional cigarette filter can be mimicked. The higher porosity at the outer filter jacket also has the advantage that the water required for degradation can penetrate into the filter insert, thereby accelerating the degradation process. Of course, the mixture used for the filter sleeve must be selected in such a way that it is not degraded by the smoker's saliva during smoking. In principle, the porosity can be varied stepwise, but also continuously.

If at least one intermediate section is arranged between a filter insert section with a predetermined particle share and a filter jacket section surrounding the filter insert with a higher particle share, the A possible configuration of the porosity varying in the radial direction is possible if the particle fraction lies between the particle fraction of the filter insert section and the filter jacket section. The filter core section, the intermediate section and the filter jacket section may refer to sections extending in the axial direction of the filter, which occupy only a part or the entire length of the filter. It is therefore conceivable for the porosity to vary continuously or in discrete sections not only in the axial direction but also in the radial direction.

The filter according to the invention can be produced with a plant having a continuous casting mold with a feed channel, downstream of which, in the casting direction, a heating device and a separating device are connected, wherein a At least two feed channels for the continuous casting mold, which feed channels extend into each other at a distance and are arranged coaxially with respect to each other and with respect to the continuous casting mold. Since the feed channels according to the invention run at intervals into one another, it is possible to produce filters whose filter inserts have different material properties than the outer filter casing in the case of different charging of the feed channels with different mixtures , whereby a porosity and/or water solubility that varies in the radial direction of the filter can be provided. By entering into the space between the feed channels extending mutually, mutually different mixtures can be introduced into the continuous casting mold through the free space created between the feed channel walls. It is proposed that each feed channel is charged with a different mixture so that the composition of the filter can be changed by switching on or off specific feed channels.

In principle, therefore, a porosity and/or water solubility that varies in the axial direction of the filter can also be provided by means of the device, for example, the continuous casting mold is first filled with the first mixture only through the feed channel and then through another feed channel. The feed channel is filled with a second mixture different from the first mixture. Another possibility for controlling a filter composition that varies in the radial direction or in the axial direction is that the mixture enters the continuous casting mold from the feed channel at different feed rates. In order to achieve a uniform transition at the boundary layer between the mixture drawn from the feed channel despite the desired water solubility gradient or the desired varying porosity, it is recommended that the feed channel have a larger diameter in the casting The direction protrudes beyond the feed channel with a smaller diameter. In this way, the feed channels each having a larger diameter open up the mixing region in which the mixture can be mixed at its transition region. Constructively favorable conditions result when the feed channel with the largest diameter forms the continuous casting mold.

In order to increase the production throughput of the filter according to the invention, a plurality of continuous casting molds extending parallel to each other can be arranged to form a continuous casting module, and a plurality of continuous casting modules can be arranged on a common base body, wherein, The basic body has a heating device for all continuous casting molds and a rotor knife extending between the heating device and the continuous casting mold as separating device. Parallelization of the production process is achieved in this way. Since the continuous casting modules are arranged on a common base body, the heating device and the rotor knives can be used for all continuous casting tools, resulting in a particularly energy-efficient production process.

With the device according to the invention it is possible to carry out a method for the continuous manufacture of filters for absorbing tobacco smoke. According to the invention, firstly a mutually different mixture comprising ceramic particles, space-occupying particles and water-soluble binder is introduced into the continuous casting mold through at least two feed channels which enter each other at a distance Extended and arranged coaxially with respect to each other and with respect to the continuous casting mold, wherein the feed speeds of mutually different mixtures in the corresponding feed channels are changed so as to be arranged in the radial direction and/or axis of the filter Water solubility and/or porosity in the direction, the continuous casting mold contents are then separated and heated to decompose the space-occupiers and form a porous structure of bonded ceramic particles. For example, if the filter is to be produced with a water solubility that decreases from the tobacco side section towards the opposite mouth side section, one feed channel can be applied with a mixture with a high binder fraction, while the other feed channel Apply a mixture with a lower binder fraction. In order to produce a sparingly water-soluble end, firstly the feed rate of the feed channel of the mixture with a high binder fraction is increased, while the feed rate of the feed channel of the mixture with a lower binder fraction is 0 or selected to be lower. If the water solubility of the filter is to be reduced in the axial direction, the feed rate of the feed channels of the mixture with a high binder fraction is reduced and the feed channel of the mixture with a lower binder fraction is increased. feed rate. Intersecting layers of the mixture are also possible by entering mutually extending feed channels, thereby also enabling water solubility to be set in the radial direction. Therefore, water solubility can be set not only in the axial direction but also in the radial direction by the arrangement of the feed channels and the change of the feed speed. The same thing certainly applies to porosity. For example, if the porosity of the filter should increase radially outward from the filter element to the filter jacket, the inner feed channel can be applied with a mixture with a lower share of occupying particles or with a smaller particle size distribution of occupying particles, while The outer feed channel is supplied with a mixture having a greater proportion of occupying particles or a larger particle size distribution of occupying particles. After setting the composition of the continuous casting mold content, the continuous casting mold content is separated by a separating device and then heated.

Description of drawings

The subject matter of the invention is shown by way of example in the drawings. In the attached picture:

Figure 1 shows a filter for adsorbing tobacco smoke according to the invention in a first embodiment,

Figure 2 shows a schematic cross-sectional view along the line II-II of Figure 1,

Figure 3 shows a schematic diagram of a device for filling three mixtures for carrying out the method according to the invention in a first embodiment,

Figure 4 shows a schematic diagram of a device for pressurization and heating for carrying out the method according to the invention in a first embodiment,

Figure 5 shows a schematic cross-section of a second embodiment of a filter according to the invention,

Figure 6 shows a partial exploded view of an apparatus according to the invention for manufacturing a filter according to the invention in a second embodiment, and

Fig. 7 shows a schematic cross-sectional view of a continuous casting module of the plant shown in Fig. 6 on an enlarged scale.

Detailed ways

The filter according to the invention for adsorbing tobacco smoke shown in FIG. 1 has a tobacco-side section 1 and a mouth-side section 2 . In order that the filter can be broken down by a large amount of water but not by the smoker's saliva, the water solubility of the filter decreases from the tobacco side section 1 to the mouth side section 2 .

This can be achieved in a particularly simple manner if the ceramic particles are bonded with a water-soluble binder 3 whose mass fraction is directed from the tobacco-side section 1 of the filter towards the opposite mouth-side section 2 Increase.

It can be seen from FIG. 1 that the mass fraction of binder 3 can be increased section by section, wherein the mouth-side section 2 has the largest binder fraction and the tobacco-side section 1 has the lowest adhesion. dose share. The adhesive portion of the middle section 4 is thus located between the adhesive portions of the tobacco-side section 1 and the mouth-side section 2 . The adhesive fraction is constant within the respective section 1 , 2 , 4 .

When the binder share is in the range of 1-2% (weight percentage) in the tobacco side section 1, in the range of 2-3% (weight percentage) in the middle section 4, in the mouth side section 2 In the range of 3-4% (weight percent), particularly well-decomposable filters are obtained.

It can be seen from FIG. 2 that the porosity can increase from the tobacco side section 1 to the mouth side section 2 . The low porosity of the tobacco side section 1 results in a particularly large effective surface area, whereby high concentrations of health-harming substances can also be bound from the tobacco smoke. As a result, the concentration of toxic substances decreases in the direction of the mouth section 2 , whereby a higher porosity can be provided there, in favor of lower flow losses.

The porosity can also be increased section by section similar to the binder fraction. The mouth side section 2 has the greatest porosity and the tobacco side section 1 has the lowest porosity. Thus, the porosity of the middle section 4 lies between the porosities of the tobacco-side section 1 and the mouth-side section 2 . The porosity is constant within the respective section 1 , 2 , 4 .

Here, when the porosity is in the range of 35-50% in the tobacco side section 1, in the range of 50-65% in the middle section 4, and in the range of 65-80% in the mouth section 2 When within the range, an effective combination of toxic substances can be achieved without giving the smoker an abnormal smoking sensation.

Figures 3 and 4 relate to a method for manufacturing a filter according to the invention. As shown in FIG. 3 , firstly, the first mixture 5 a is filled into the mold 6 . After that, the mold 6 is filled with the second mixture 5b and the third mixture 5c. Between the filling of the different mixtures 5 a , 5 b , 5 c it is possible to smooth out any accumulation cones 7 which may have formed during the filling. This can be done, for example, via the vibrating plate 8 . The mixture 5a, 5b, 5c comprises ceramic particles, space-occupied particles and a water-soluble binder, wherein, for each mixture 5a, 5b, 5c, the proportion of binder and/or the proportion of space-occupied particles or the size distribution of space-occupied particles can be Variety. In the exemplary embodiment shown in FIG. 2 , the mixture 5 a has the largest binder fraction and occupying particles with the largest particle size distribution in order to produce a large porosity. The mixture 5 a is thus provided for forming the mouth section 2 . Mixture 5 b has a lower binder fraction and occupying particles with a smaller particle size distribution than mixture 5 a and is therefore provided for the middle section 4 . The mixture 5 c has the lowest binder fraction and the placeholder particles with the smallest particle size distribution and is provided for forming the tobacco side section 1 . Of course, the layering of the mixtures 5a, 5b, 5c can also be carried out in reverse order. Methods utilizing more than three mixtures can also be set up if a differential design for porosity or water solubility is desired. The particle size distribution of the occupying particles can preferably lie in the range between 15 and 300 nm. However, the variation of porosity can also be achieved by changing the mass fraction of occupying particles while keeping the particle size distribution constant.

After filling, as can be seen from FIG. 4 , the layered mixtures 5 a , 5 b , 5 c are pressed together, for example, by means of a stamp 9 and heated by means of a heating device 10 . Due to the heat of action, the occupying particles, for example NH ₄ HCO _{3 ,} are converted into the gas phase as NH ₃ , H ₂ O and CO ₂ and thus leave voids 11 in the porous structure 12 , as disclosed in FIG. 2 .

Figure 5 shows a second embodiment of the filter according to the invention, wherein the elasticity decreases inwards. Furthermore, the filter has a water solubility that decreases from the tobacco-side section 1 towards the opposite mouth-side section 2 . The radial inward reduction of the elasticity can be achieved in a simple manner by providing an elastic felted ceramic fiber layer 13 . Another possibility consists in that the porosity, ie the volume of the interspaces 11 of the filter, increases radially outward from the filter insert 14 to the filter sleeve 15 .

The increase of the porosity in the radial direction outwards can be discontinuous in that between the filter insert section 16 with a predetermined particle fraction and the filter element 14 surrounding the filter insert 14 with a higher fraction of particles Arranged between the sleeve sections 17 is at least one intermediate section 18 , whose particle share is between the particle share of the filter insert section 16 and the filter jacket section 17 .

FIG. 6 shows an apparatus according to the invention for producing a filter according to the invention with a continuous casting mold 19 downstream of which, in casting direction 20 , a separating device 21 and a heating device 10 are connected. As can be seen from FIG. 7 , each continuous casting mold 19 has a feed channel 22 which extends into each other at intervals, that is, on the inner surface of the outer feed channel 22 and the inner feed channel 22 A middle passage is formed between the outsides of the sleeves. Here, the continuous casting tool 19 can form the feed channel 22 with the largest tube diameter. The feed channels 22 can be fluidically connected by different supply channels 24 , which supply the feed channels 22 with different mixtures, for example by means of pumps.

In order to improve the mixing of the mixture conveyed through the different feed channels 22 and to set material properties that vary in the axial direction, the feed channels 22 with the larger diameter can protrude beyond the feed channels with the smaller diameter in the casting direction 20 . Material channel 22.

A plurality of continuous casting tools 19 extending parallel to each other can be combined to form a continuous casting module 25 . As disclosed in FIG. 6, a plurality of continuous casting modules 25 can advantageously be arranged on a base body 26, wherein the base body 26 has perforations 27 corresponding to the continuous casting mold 19 for guiding the continuous casting mold content or heated filter. Base body 26 here has a common heating device 10 for all continuous casting molds 19 and a rotor knife extending between heating device 10 and continuous casting mold 19 as separating device 21 . Furthermore, the base body 26 can also have a heat sink 28 .

After setting the filter composition in the continuous casting mold 19 through the feed channel 22 , the continuous casting mold content is pressed through the perforations 27 . During extrusion, the continuous casting mold contents are separated by the separating device, then heated and hardened by the heating device 10 . A cooling step through the cooling body 28 can then also be provided.

Claims (15)

1. A filter for adsorbing unhealthy tobacco smoke constituents, having ceramic particles bound into a porous structure (12), characterized in that the filter has a water solubility which decreases from a tobacco side section (1) towards an opposite mouth side section (2).

2. A filter according to claim 1, characterised in that the ceramic particles are bonded with a water-soluble binder (3), the mass fraction of which increases from the tobacco-side section (1) towards the opposite mouth-side section (2) of the filter.

3. The filter according to claim 2, characterized in that the filter comprises at least three sections (1,2,4) having mutually different and respectively constant adhesive portions.

4. A filter according to claim 3, characterised in that the binder fraction is in the range of 1-2% by weight in the tobacco side section (1), in the range of 2-3% by weight in the at least one intermediate section (4), in the range of 3-4% by weight in the mouth side section (2).

5. A filter according to any of claims 1-4, wherein the porosity of the filter increases from the tobacco side section (1) towards the opposite mouth side section (2).

6. The filter according to claim 5, characterized in that it has at least three sections (1,2,4) with different and respectively constant porosities from each other.

7. A filter according to claim 6, wherein the porosity is in the range of 35-50% in the tobacco side section (1), 50-65% in the middle section (4), 65-80% in the mouth side section (2)

8. A filter according to any one of claims 1-7, characterised in that the elasticity of the filter decreases inwards in the radial direction.

9. A filter according to any one of claims 1-8, characterised in that the porosity of the filter increases radially outwards from the filter insert (14) to the filter casing (15).

10. The filter according to claim 9, characterized in that at least one spacer section (18) is provided between the filter element section (16) having a predetermined space-occupying particle fraction and the filter jacket section (17) surrounding the filter element (14) having a higher space-occupying particle fraction, the space-occupying particle fraction of the spacer section being located between the space-occupying particle fractions of the filter element section (16) and the filter jacket section (17).

11. A method for manufacturing a filter for adsorbing tobacco smoke, characterized in that a mixture (5a, 5b, 5c) comprising ceramic particles, space-occupying particles and a water-soluble binder (3) different from each other is filled successively into a mould (6), after which the mould contents are pressed and heated to decompose the space-occupying particles and form a porous structure (12) of bonded ceramic particles.

12. A plant for manufacturing a filter according to any one of claims 1 to 10, with a continuous casting mould (19) having a feed channel (22) to which a heating device (10) and a separating device (21) are connected downstream in the casting direction (20), characterized in that at least two feed channels (22) for the continuous casting mould are provided which extend at a distance into each other and are arranged coaxially with respect to each other and with respect to the continuous casting mould (19).

13. The apparatus as claimed in claim 12, characterized in that the feed channel (22) with the larger diameter protrudes beyond the feed channel (22) with the smaller diameter in the casting direction (20).

14. An apparatus according to claim 13, characterized in that a plurality of continuous casting moulds (19) extending parallel to each other are arranged as one continuous casting module (25) and a plurality of continuous casting modules (25) are arranged on a common base body (26), wherein the base body (26) has one heating device (10) and one rotor blade as a separating device (21) extending between the heating device (10) and the continuous casting mould (19) for all continuous casting moulds (19).

15. A method for the continuous manufacture of a filter for adsorbing tobacco smoke, characterized in that a mutually different mixture comprising ceramic particles, space-occupying particles and a water-soluble binder (3) is first introduced into a continuous casting mould (19) through at least two feed channels (22) extending at a distance into each other and arranged coaxially with respect to each other and with respect to the continuous casting mould (19), wherein the feed speed of the mutually different mixture in the respective feed channels (22) is varied in order to set the water-solubility and/or porosity in the radial and/or axial direction of the filter, and then the continuous casting mould contents are divided and heated to decompose the space-occupying particles and form a porous structure (12) of the bonded ceramic particles.

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