EP1103193A2

EP1103193A2 - Gas filter

Info

Publication number: EP1103193A2
Application number: EP99125348A
Authority: EP
Inventors: Kyriakos Zafiriou
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-10-21
Filing date: 1999-12-21
Publication date: 2001-05-30

Description

The present invention relates to a filter for filtering gases, particularly for filtering the smoke of tobacco products, for example cigarettes or cigars.
Tobacco products, especially cigarettes, are frequently sold together with a filter, which is part of the product. The purpose of such filters is to reduce the fraction of harmful substances being part of the tobacco smoke. By doing so, the taste of the smoke should not been altered. In addition, the filter should be made from a cheap and easy to handle material.
Within the prior art, these problems are generally solved by using filters made from cotton wool. This material is easy to handle and does not affect the taste of the tobacco smoke. Nevertheless, the filter capacity of this material is limited.
It is therefore the object of the present invention to provide a small, cheap and easy to handle filter being capable of significantly reducing the harmful parts of gases, particularly tobacco smoke.
According to the present invention this problem is solved by providing a filter having a filter housing, wherein particles of grinded stone having high porosity and absorption capacity in powder form (grinded stone) are used as a filter material and is arranged as such in the housing of the filter. The term "powder form" as used herein stands for particle diameters of up to 1 mm, wherein for the application of the filter as an integrated part of a cigarette or cigar, the particle diameters preferably lie within the range of 0,1 to 0,7 mm. In principle, within the present invention, grinded stone comprising particles having a diameter of down to several micrometers may be used. Preferably, said stone is selected from the group consisting of lime stone, asbestos stone, lava stone, pumice stone and miarolitic stone. The filter may be used for filtering gases, particularly the smoke of tobacco products, wherein the tobacco products, like cigarettes and cigars, are arranged relatively to the filter to as to pass their fumes through the filter.
Preferably, the harmful parts of the gases are reduced to about 50% or more, preferably to about 70% or more, more preferably to about 80% or more and most preferably to about 90% or more. In case of cigarette smoke this reduction applies to e.g. nicotine and tar as well as other harmful components.
The particles of grinded stone in powder form may be obtained by the following method comprising the following stages:
(b) grinding small pieces of stone to particles in powder form
(c) hydro-spinning of the particles obtained in (b)
(d) drying the product obtained in (c)
(e) grinding the dried product obtained in (d) to particles in powder form.
Furthermore within said method, the following further stage may be carried out before conducting steps (b) to (e):
(a) crushing of rocks of stone into small pieces of pumice stone.
Subsequently, the particles of grinded stone in powder form as obtained in (e) are introduced into the housing of the filter (step (f)).
Thus, the invention refers to a method for producing a filter for filtering gases with a housing containing particles of grinded stone in powder form, wherein said method comprises at least the following steps (b) to (f) defined above.
The hydro-spinning step (c) is conducted in a metallic cylindrical device, such as a spinning drum exhibiting a vertikal spindle, which is rotating with a speed of 500 or more revolutions per minute, while at the same time water in sprayed onto the particles to be hyrdo-spun. Thereby, particles having a relatively large porosity and high capacity of absorbing the harmful parts of gases are obtained.
If the housing is of cylindrical shape and, in addition, has a diameter of 4 mm to 15 mm, preferably 7 to 9 mm, and a length of 7 mm to 20 mm, the filter works best in connection with standard tobacco products. The housing itself may comprise or consist of a plastic tube for easy handling. Preferably, PVC or polyethylene is used here for the plastic tube. Furthermore, other materials may be used for the housing. In another preferred embodiment of the invention, the housing comprises or consists of paper as used in conventional cigarettes, strong paper, as for example cardboard, and/or of metal. For the use in cigars, tobacco leafs may be used as the housing. Furthermore, also a housing made of a thin sheet of cotton may be used. The housing may be printed or surrounded by a label of paper or plastic or an engraved label.
If a receptor with an interior space is added to the filter, objects emitting gases like standard tobacco products, may be introduced and fixed at that receptor, so that the filter may be used as an additional independent filter. In a preferred embodiment of the invention, said receptor is adaptable to different object sizes which should be fixed at the receptor. The receptor can be formed like a screw clamp. The connection between the filter and the gas emitting object, e.g. the cigarette, may be achieved by pressure, by gluing or any other suitable means.
The interior of the filter may for example comprise at least one sequence of at least two sections arranged in the housing, wherein the first section of the sequence is filled with grinded stone and the second section with cotton wool. Preferably, the length of the first section is between 6 mm to 18 mm, preferably from 9 mm to 15 mm, and the length of the second section is between 15 mm to 25 mm. A different, but also properly working filter sequence within the housing is a combination of at least four sections, wherein the first section is filled with said grinded stone, the second and the forth section with cotton wool and wherein the third section is empty. Preferably, the length of each of the four sections is within a range from 3 mm to 8 mm, best results are achieved with lengths from 4 mm to 6 mm.
For a better understanding of the invention, reference will now be made, by way of example, to the accompanying drawings showing the following:

Figure 1:: Schematic representation of a preferred embodiment of the inventive filter with four sections
Figure 2:: Schematic representation of another preferred embodiment of the inventive filter with two sections and receptor,
Figure 3:: Schematic representation of a further preferred embodiment of the inventive filter with holes in the bottom.

Figure 1 shows a filter 1, which may be used instead of a cotton wool filter within a normal cigarette. The filter is of cylindrical shape, the cylinder wall 2 is for example made of plastic or paper as in commercially available cigarettes or a tobacco leaf as used in cigars.
The filter portion itself is preferably divided into four equal segments. Segment 3, which is next to the tobacco of the cigarette or cigar, is filled with grinded stone. This portion is limited by section 4, filled with cotton wool. To the left, the next section is an empty section 5, again followed by a section filled with cotton wool 6. The main filter effect happens in section 3, when the smoke passes the grinded stone. These stones do have a relatively large surface, so that the harmful portions of the smoke, especially the nicotine and tar is deposited on this surface. The big advantage of the stone filter is, that it provides a high filter capacity, is easy and cheap to produce and especially does not alter the taste of the smoke. The harmful parts of the smoke may be reduced to about 90% or more.
The next three sections comprise a combination of cotton wool, empty room and cotton wool.
As shown in figure 2, the filter according to the invention may also be used as an additional filter, to be used in connection with standard cigarettes or other tobacco products. Shown is a filter 1 with a cylindrical outer part 2 and an opening 8, surrounded by a housing 7, working as a receptor. Into the opening 8, a cigarette or similar tobacco product may be inserted. The smoke is then first directed through the filter portion 3, comprising grinded stone, and then through a portion 4, comprising cotton wool.
It is clear from the above, that the filter 1 of figure 2 may also consist of four sections as described and shown in figure 1 and vice versa. In addition, any other combination of sections is possible, as long as one section comprises grinded stone.
Figure 3 shows a further preferred embodiment of the inventive filter 1. It consists of a plastic tube 2 with a length of 20 mm and a total external diameter of 7 mm, an internal diameter of 5 mm and a wall width of 1 mm. The bottom 9 is slightly round and has 5 holes 10, each of said holes has a diameter of 0,5 mm. Four holes are arranged perimetrically close to the periphery in form of a cross and the fifth one is located in the center of said cross. At the top of the tube 2, there is a cover 11 which is made of the same material as the tube 2, preferably of plastic as for example PVC or polyethylene. The cover 11 consists of two parts. The upper part 12 has a thickness of 1 mm and the same diameter as the tube 2, namely 7 mm. The second part 13 of the cover 11 has such a form that it can be stucked into the tube 2. The cover 11 has also five holes 10 which are arranged in the same form as the holes of the bottom. The whole tube 2 is filled with grinded stone. With the help of this embodiment of the inventive filter, the harmful parts of the smoke which pass the filter, particularly nicotine, are reduced to about 95%.
As become apparent from the above, the present invention also relates to a cigarette or cigar comprising a filter as defined herein as an integrated part of said cigarette or cigar. For said embodiment, preferably grinded stone having a particle diameter of from 0,1 to 0,7 mm are used.

Claims

Filter (1) for filtering gases, particularly the smoke of tobacco products, comprising a housing (2), characterised in that said housing (2) contains particles of grinded stone having high porosity and absorption capacity in powder form (3).
Filter according to claim 1, wherein said stone is selected from the group consisting of lime stone, asbestos stone, lava stone, pumice stone and miarolitic stone.
Filter (1) according to claim 1 or 2, characterised in that said housing (2) is of cylindrical shape.
Filter (I) according to claim 3, characterised in that said housing (2) has a diameter from 4 mm to 15 mm, preferably from 7 mm to 9 mm.
Filter (1) according to any of the preceding claims, characterised in that said housing (2) comprises a plastic tube.
Filter (1) according to any of the preceding claims, characterised in that said filter (1) comprises a receptor (7) with an interior space (8) in which an object emitting said gases to be filtered may be introduced and fixed.
Filter (1) according to claim 6, characterised in that said receptor (7) is adaptable to different object sizes.
Filter (1) according to any of the preceding claims, characterised in that said filter (1) comprises at least one sequence of at least two sections arranged in said housing (2), wherein a first section (3) of said sequence is filled with said grinded stone and a second section (4) of said sequence is filled with cotton wool.
Filter (1) according to claim 8, characterised in that the length of said first section (3) is from 6 mm to 18 mm, preferably from 9 mm to 15 mm, and in that the length of said second section (4) is from 15 mm to 25 mm.
Filter (1) according to any of claims 1 to 7, characterised in that said filter (1) comprises at least one sequence of at least four sections arranged in said housing (2), wherein a first section (3) of said sequence is filled with said grinded stone, a second section (4) of said sequence is filled with cotton wool, a third section (5) of said sequence is empty and a fourth section (6) is filled with cotton wool.
Filter (1) according to claim 10, characterised in that the length of each of said four sections (3, 4, 5, 6) is from 3 mm to 8 mm, preferably from 4 mm to 6 mm.
Method for producing a filter for filtering gases with a housing containing particles of grinded stone having high porosity and absorption capacity in powder form, said method comprising at least the following steps:

(b) grinding small pieces of stone having high porosity and absorption capacity to particles in powder form

(c) hydro-spinning of the particles obtained in (b)

(d) drying the product obtained in (c)

(e) grinding the dried product obtained in (d) to particles in powder form.
Cigarette or cigar comprising a filter according to any of claims 1 to 10 as an integrated part of said cigarette or cigar.