FI68953C - FOERBAETTRINGAR BETRAEFFANDE FILTER FOER TOBAKSROEK - Google Patents

Description

68953

This invention relates to tobacco smoke filters for use in smoking articles, such as cigarettes.

It is well known to provide filter cigarettes with ventilation means 5 which allow ventilation air to enter the filter. The purpose of this is to reduce the proportion of toakan smoke in the main stream. It has been found that when ventilation air flows into a filter comprising a fibrous filter material, for example a cellulose gun-10 plug, through a vent area extending around the filter, the tobacco smoke escapes from the filter in an axial flow smaller than the diameter of the filter plug.

This relatively narrow stream of tobacco smoke hits a limited area of the 15 mouthpieces in the smoker's mouth. The present invention relates to a tobacco smoke filter which exhibits stimulation of the taste buds over a wide area in the smoker's mouth.

The present invention provides a tobacco smoke filter comprising a rod-like stopper of filter material having at least one airflow channel at the periphery of the plug, said at least one airflow passage having an outlet at the mouth end of said plug and an inlet apart from the mouth end and at least one the airflow channel has an area where the depth continuously decreases along the airflow channel as it moves toward the mouth end of the plug.

Suitably said at least one air flow duct 30 has an area which decreases in depth and which extends substantially up to the mouth end of the plug. There are preferably a plurality of said air flow channels, each of which is formed partly by one of a plurality of grooves on the circumferential surface of the filter plug and partly by the inner surface of the wrapper around the filter plug. In this case, the width of the grooves 2 68953 may be constant or may increase or decrease as the filter plug moves in the mouth direction.

For a clear understanding of the invention and its ease of practice, reference is now made, by way of example, to the schematic drawings, in which Figure 1 is a fragmentary longitudinal sectional view of a snodatin-terminated cigarette; Figure 2 shows the mouth end of the filter of the cigarette of Figure 1; Fig. 3Q shows an oral end of a filter having a slightly different shape from the filter shown in Fig. 1; and Figure 4 shows a structural view of a part of the circumferential surface of a filter of another shape.

The cigarette according to Kuyan 1 comprises a rod 1 of cut tobacco wrapped in cigarette paper 2 and a filter 3 consisting of a self-supporting filter plug 4 made of fibrous cellulose acetate material.

The outer circumference of the plug 4 has several, eight shown, 20 parallel, longitudinal grooves 5 - see also kuyaa 2. As can be seen from Figure 1, the grooves 5 extending from the mouth end of the plug 4 less than half a length along the entire length of the plug are formed so that the depth of each decreases towards and substantially until the mouth end 25 of the plug. A suitable method of forming the grooves 5 is to apply a hot molding treatment to the plug 4 or, preferably, to a piece of filter rod from which the plug is cut, as disclosed in GB Patent 1,507,765, using suitably shaped molding means.

3Q The surfaces of the grooves 5 can be made impermeable.

To attach the filter 3 to the cigarette rod 1, 2, a protective wrapper is used which, in the areas where it covers the grooves 5, together with the walls of the grooves 5 forms air flow channels 8. A row of ventilation holes 9 in the protective wrapper 7 on an enlarged scale 35 surrounds 3 68953 plugs at 4 the arrangement being such that each of the air flow channels 8 communicates with at least one hole 9.

When the cigarette according to Figure 1 is smoked, the ambient air is sucked through the ventilation holes 9 into the air flow ducts 8. The air passes along the air flow ducts 8 towards their outlet end unmixed or substantially unmixed with the tobacco smoke. Since the depth of the grooves 5 partly determines the air flow channels 8, as the depth decreases, the air in the flow direction of the ventilation air along the channel 8 escapes from the channels 8 to the smoker's mouth, whereby its flow is directed radially outwards. Thus, a decomposing air flow is formed, which mixes the tobacco smoke 15 leaving the mouth end of the filter plug 4 under the effect of vacuum suction and thus the tobacco smoke comes into contact with the taste buds over a relatively wide area in the smoker's mouth. The smoker perceives this tobacco smoke as an improvement in quality.

The filter, the mouth end of which is shown in Fig. 3, comprises a plug 4 'which, instead of longitudinally extending circumferential grooves, comprises a single annular circumferential groove 5'. In the longitudinal direction of the plug 4 ', the outline of the groove 5' is similar to the outline of the bottom of the grooves 5 of the plug shown in Fig. 1. A rigid wrapper 25 or mouthpiece 7 ', which may be made of plastic material, surrounds the stopper 4' and attaches to the end portion of the cigarette rod in the same manner as the cigarette wrapper 7 shown in Figure 1. The wrapper 7 'must be rigid so as to circumferentially the mouth-side, annular end opening indicated by the number 6 of the air flow channel 5 'formed by the groove 5' and the jacket 7 'remains open when the filter is used.

The effect of the filter according to Figure 3 is similar to that of the filter shown in Figures 1 and 2.

35 The ambient air is drawn into the air flow passage 8 'through holes in the wrapper or mouthpiece 7' (not shown) and the contour of the groove 5 'enters the smoker's mouth in a disintegrating flow, causing smoke to enter the grown area.

Fig. 4 shows, in structural view, a pattern of circumferential grooves which can be used as an alternative to the position of the longitudinal grooves 5 of the filter according to Fig. 1 or the position of the only annular groove 5 'surrounding the circumference of the filter according to Fig.

10 In Fig. 4, reference numeral 10 denotes the mouth end of the filter plug 11. It has a first group of circumferential, parallel grooves 13 which form a small angle with the axis of the plug 11 and a second, similar group of grooves 14 which form substantially the same angle with the axis but in the opposite direction.

The two groove groups 13, 14 intersect to form a network-like structure. As in one group of grooves 5, each groove 13, 14 has an area whose depth decreases as it moves towards and substantially towards the mouth end 10 20 of the plug 11. For use, the plug 11 is covered with a wrapper (not shown) which allows air to flow into the grooves 13, 14 at their initial points and the decomposition effect of the tobacco smoke is achieved in the same way as shown in connection with the filters described above.

The wrapper for the filter plug may consist of a permeable wrapper for the filter plug and a longer, impermeable protective wrapper that covers the wrapper wrapper and attaches 30 filter plugs to the tobacco rod 2. In this case, only cases of vent holes are needed.

The filter plug may, if desired, consist of two partial plugs, one comprising grooves 5, 13, 14 or a single circumferential groove 5 'and the other of the plug being smooth.

35 If desired, the ventilation holes can be formed by a micro-perforated area in the protective wrapper.

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Claims (10)

A smoke filter, consisting of a rod-like plug of filter material and having at least one air flow channel on the periphery of the plug, said air flow channel having an outlet opening at the mouth end of the plug and an inlet opening at a distance from the mouth end thereof, the air flow channel (8.8 ') has a region where the depth progressively decreases along the air flow channel 10. towards the mouth end of the plug (4.4', 10). 2. Filter according to claim 1, characterized in that the region of progressively decreasing depth in the air flow duct continues substantially to the orifice end of the filter plug (4,4 ', 10). Filter according to any of the preceding claims, characterized in that a cover (7), which surrounds the plug (4,4 ') and permits ambient air to enter said air flow duct (8,8') at a location at a distance from the mouth end of the plug. 4. A filter according to claim 3, characterized in that it has several air flow channels (8), each defined partly by a plurality of longitudinal grooves (5) in the peripheral surface of the filter plug (4) and partly by the internal surface. of the cover (7). 5. Filter according to claim 4, characterized in that the grooves (5,13,14) have a constant width. Filter according to claim 4, characterized in that the grooves (5) increase in width towards the mouth end of the plug (4). Filter according to any one of claims 4-6, characterized by two sets of said grooves (13, 14), and in that the grooves (13) in the first set are spirally shaped in the first direction and the grooves (13). 14) in the second set are helical in the opposite direction, whereby eating a groove (13) in the first set cuts several grooves (14) in the second set