FILTER FOR THE SORPTION OF COMPONENTS OF TOBACCO SMOKE WHICH ARE HARMFUL TO HEALTH

Abstract

A filter for sorption of components of tobacco smoke which are harmful to health comprises ceramic particles bonded to form a porous structure (12). In order to avoid contamination within a short period of time even when the filter is not properly disposed of, and without causing a loss in sorption or in the smoking sensation, the filter has decreasing water solubility from a tobacco-side portion (1) to an opposite mouth-side portion (2).

Claims

1. A filter for sorption of components of tobacco smoke that are harmful to health, said filter comprising: ceramic particles bonded to form a porous structure; wherein the filter has decreasing water solubility from a tobacco-side portion to an opposite mouth-side portion.

2. The filter according to claim 1, wherein the ceramic particles are bonded with a water-soluble binder, the water-soluble binder having a mass fraction that increases from the tobacco-side portion to the opposite mouth-side portion of the filter.

3. The filter according to claim 2, wherein the filter further comprises a third portion, said tobacco-side portion, said mouth-side portion, and the third portion each having a respective different and constant binder content.

4. The filter according to claim 3, wherein the third portion comprises at least one middle portion, and the binder content in the tobacco-side portion is in a range of 1-2 wt %, in the at least one middle portion in a range of 2-3 wt %, and in the mouth-side portion in a range of 3-4 wt %.

5. The filter according to claim 1, wherein the filter has a porosity that increases from the tobacco-side portion to the opposite mouth-side portion.

6. The filter according to claim 5, wherein the filter further has a third portion, said tobacco-side portion, said mouth-side portion, and the third portion each having a respective porosity that differs from the porosities of the other portions and is constant in said portion.

7. The filter according to claim 6, wherein the third portion comprises at least one middle portion, and the porosity in the tobacco-side portion is in a range of 35-50%, in the middle portion in a range of 50-65% and in the mouth-side portion (23 in a range of 65-80%.

8. The filter according to claim 1, wherein the filter has an elasticity that decreases inwardly in a radial direction of the filter.

9. The filter according to claim 1, wherein the filter has a porosity that increases radially outwardly from a filter core to a filter shell of the filter.

10. The filter according to claim 9, wherein at least one intermediate portion (18) is supported between a filter core portion having a predetermined placeholder particle fraction and a filter shell portion surrounding the filter core and having a placeholder particle fraction higher than the predetermined placeholder particle fraction, wherein the placeholder particle fraction of said intermediate portion lies between the placeholder particle fractions of the filter core portion and the filter shell portion.

11. A method for producing a filter for sorption of tobacco smoke, said method comprising: filling successively mutually different mixtures comprising ceramic particles, placeholder particles and water-soluble binder into a mold; and pressing and heating contents of the mold so as to decompose the place-holder particles and to bond the ceramic particles so as to form a porous structure.

12. A device for producing a filter according to claim 1, comprising a continuous casting mold that has inlet channels; and a heating unit and a separating device supported downstream of said inlet channels in a casting direction, a heating unit and a separating device; wherein the continuous casting mold has characterized in that at least two inlet channels that extend at a distance into one another and are arranged coaxially with respect to one another and with respect to the continuous casting mold.

13. The device according to claim 12, wherein wherein some of the inlet channels have a larger diameter and some of the inlet channels have a smaller diameter, wherein the inlet channels with the larger diameter project beyond the inlet channels with the smaller diameter in the casting direction.

14. The device according to claim 13, wherein the continuous casting mold is one of a plurality of continuous casting molds extending parallel to one another that are formed into a continuous casting module, and said continuous casting module is one of a plurality of continuous casting modules that are arranged on a common base body, wherein the base body supports the heating unit and the separating unit comprises a rotor blade extending between the heating unit and the continuous casting molds.

15. A method for the continuous production of a filter for the sorption of tobacco smoke, said method comprising: initially introducing mixtures differing from one another and comprising ceramic particles, placeholder particles and water-soluble binder into a continuous casting mold through at least two inlet channels that extend into one another at a distance and are arranged coaxially with one another and with respect to the continuous casting mold; varying inlet velocities of the mixtures differing from one another in the respective inlet channels in a radial and/or axial direction of the filter so as to adjust water solubility and/or the porosity of the filter, and then fractionating and heating the continuous casting mold contents are so as to decompose the placeholder particles and bind the ceramic particles so as to form the porous structure of said bound ceramic particles.

16. The filter according to claim 4, wherein the filter has a porosity that increases from the tobacco-side portion to the opposite mouth-side portion, and said tobacco-side portion, said mouth-side portion, and the third portion each have a respective porosity that differs from the porosities of the other portions, wherein the porosity in the tobacco-side portion is in a range of 35-50%, in the middle portion in a range of 50-65% and in the mouth-side portion in a range of 65-80%.

17. The filter according to claim 16, wherein the filter has an elasticity that decreases inwardly in a radial direction of the filter, and a porosity that increases radially outwardly from a filter core to a filter shell of the filter.

18. The filter according to claim 17, wherein at least one intermediate portion is supported between a filter core portion having a predetermined placeholder particle fraction and a filter shell portion surrounding the filter core and having a placeholder particle fraction higher than the predetermined placeholder particle fraction, wherein the placeholder particle fraction of said intermediate portion lies between the placeholder particle fractions of the filter core portion and the filter shell portion.

Description

BRIEF DESCRIPTION OF THE INVENTION

[0024] In the drawing, the subject matter of the invention is shown by way of example, wherein:

[0025] FIG. 1 shows a filter according to the invention for sorption of tobacco smoke in a first embodiment,

[0026] FIG. 2 shows a schematic section along line II-II of FIG. 1,

[0027] FIG. 3 shows a schematic representation of a device for carrying out the method according to the invention for filling three mixtures in a first embodiment,

[0028] FIG. 4 shows a schematic representation of a device for carrying out the method according to the invention for pressing and heating in a first embodiment,

[0029] FIG. 5 shows a schematic cross-section of a second embodiment of a filter according to the invention,

[0030] FIG. 6 shows a partial exploded view of a device according to the invention for producing a filter according to the invention in a second embodiment, and

[0031] FIG. 7 shows a schematic section through a continuous casting module of the device shown in FIG. 6 on an enlarged scale.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] A filter for sorption of tobacco smoke according to the invention shown in FIG. 1 has a tobacco-side portion 1 and a mouth-side portion 2. In order for the filter to be degraded by larger amounts of water, but not by the saliva of a smoker, the water solubility of the filter decreases from the tobacco-side portion 1 to the mouth-side portion 2.

[0033] This can be achieved in a particularly simple manner if the ceramic particles are bonded with a water-soluble binder 3, the mass fraction of which increases from the tobacco-side portion 1 to the opposite mouth-side portion of the filter 2.

[0034] As can be seen from FIG. 1, the increase in the mass fraction of the binder 3 can take place portion by portion, with the mouth-side portion 2 having the largest binder fraction and the tobacco-side portion 1 having the lowest binder fraction. The binder content of the middle portion 4 is therefore between the binder content of the tobacco-side portion 1 and the mouth-side portion 2. The binder content within the respective portions 1, 2, 4 is constant.

[0035] A particularly well-degradable filter results if the binder content in the tobacco-side portion 1 is in a range of 1-2 wt %, in the middle portion 4 in a range of 2-3 wt % and in the mouth-side portion 2 in a range of 3-4 wt %.

[0036] As can be seen from FIG. 2, the porosity can increase from the tobacco-side portion 1 to the mouth-side portion 2. The low porosity of the tobacco-side portion 1 results in a particularly large effective surface area, which means that even high concentrations of harmful substances from the tobacco smoke can be bound. The concentration of toxic substances therefore decreases in the direction of the mouth-side portion 2, which means that a higher porosity can be provided there in favor of lower flow losses.

[0037] The increase in porosity can also take place portion by portion, analogously to the binder content. The mouth-side portion 2 has the highest porosity and the tobacco-side portion 1 the lowest porosity. Consequently, the porosity of the middle portion 4 lies between the porosity of the tobacco-side portion 1 and the mouth-side portion 2. The porosity within the respective portions 1, 2, 4 is constant.

[0038] Effective binding of toxic substances without giving the smoker an unfamiliar smoking sensation is achieved when the porosity in the tobacco-side portion 1 is in a range of 35-50%, in the middle portion 4 in a range of 50-65%, and in the mouth-side portion 2 in a range of 65-80%.

[0039] FIGS. 3 and 4 refer to a method for manufacturing the filter according to the invention. As shown in FIG. 3, first a first mixture 5a is filled into a mold 6. Whereupon a second mixture 5b and third mixture 5c are filled into the mold 6. Between filling of the different mixtures 5a, 5b, 5c, any dump cone 7 formed during filling can be leveled. This can be carried out, for example, by a vibrating plate 8. The mixtures 5a, 5b, 5c comprise ceramic particles, placeholder particles and water-soluble binder, wherein for each mixture 5a, 5b, 5c the binder fraction and/or the placeholder particle fraction and/or the placeholder particle size distribution can vary. In the exemplary embodiment shown in FIG. 2, mixture 5a has the largest binder fraction and, to produce a large porosity, placeholder particles with the largest particle size distribution. Accordingly, mixture 5a is intended to form the mouth-side portion 2. Mixture 5b has both a lower binder fraction and placeholder particles with a smaller particle size distribution than mixture 5a and is thus intended for the middle portion 4. Mixture 5c has the lowest binder fraction and placeholder particles with the lowest particle size distribution and is provided for forming the tobacco-side portion 1. Obviously, the layering of mixtures 5a, 5b, 5c can also be done in reverse order. A method with more than three mixtures can also be provided if a more differentiated design of porosity or water solubility is desired. Preferably, the particle size distribution of the placeholder particles can range from 15 to 300 nm. However, variation of the porosity can also be achieved by changing the mass fraction of the placeholder particles while maintaining the same particle size distribution.

[0040] After filling, as can be seen from FIG. 4, the layered mixtures 5a, 5b, 5c are pressed together by, for example, a ram 9 and heated by a heating unit 10. Due to the applied heat, the placeholder particles, for example NH.sub.4HCO.sub.3, are transferred to the gas phase as NH.sub.3, H.sub.2O and CO.sub.2, thereby leaving gaps 11 in the porous structure 12, as disclosed in FIG. 2.

[0041] FIG. 5 shows a second embodiment of a filter according to the invention, in which the elasticity decreases inwardly. Furthermore, the filter has a decreasing water solubility from a tobacco-side portion 1 to an opposite mouth-side portion 2. The radial inward decrease in elasticity can be achieved in a simple manner by providing an elastic, matted ceramic fiber layer 13. Another possibility is when the porosity, i.e. the volume of the gaps 11 of the filter increases radially outward from a filter core 14 to a filter shell 15.

[0042] The increase in porosity in the radial direction outward can be discrete in that at least one intermediate portion 18 is provided between a filter core portion 16 having a predetermined placeholder particle fraction and a filter shell portion 17 surrounding the filter core 14 and having a higher placeholder particle fraction, the placeholder particle fraction of which lies between the placeholder particle fractions of the filter core portion 16 and filter shell portion 17.

[0043] FIG. 6 shows a device according to the invention for producing a filter according to the invention with continuous casting molds 19, downstream of which in the casting direction 20 are a separating device 21 and a heating unit 10. As can be seen from FIG. 7, each continuous casting mold 19 has inlet channels 22 which extend into one another at a distance, i.e. with the formation of an intermediate channel between the shell inner surface of the outer inlet channel 22 and the shell outer surface of the inner inlet channel 22. The continuous casting mold 19 may thus form the inlet channel 22 with the largest tube diameter. The inlet channels 22 can be flow-connected via different supply channels 24, which supply the inlet channels 22 with different mixtures via pumps, for example.

[0044] For improved mixing of mixtures conveyed through the different inlet channels 22 and to adjust material properties that vary in the axial direction, the larger diameter inlet channels 22 may project beyond the smaller diameter inlet channels 22 in the casting direction 20.

[0045] A plurality of continuous casting molds 19 extending parallel to each other may 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 apertures 27 corresponding to the continuous casting molds 19 for guiding the continuous casting mold contents or the heated filter. In this regard, the base body 26 has a common heating unit 10 for all continuous casting molds 19 and a rotor blade extending between the heating unit 10 and the continuous casting molds 19 as a separating device 21. The base body 26 may also have a heat sink 28.

[0046] After adjusting the filter composition in the continuous casting mold 19 via the inlet channels 22, the continuous casting mold contents are forced through the apertures 27. During the pushing through, the continuous casting mold content is fractionated by a separating device and then heated and hardened by a heating unit 10. Subsequently, a cooling step can be provided by a heat sink 28.