Concentric core filter

Details Concentric core filter Concentric core filter

1997-02-18

1998-08-04

Yu, Mickey

Tobacco

Smoke separator or treater

131344, A24B 1500

Patent

active

057879028

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to a ventilated cigarette filter of the type having a tobacco smoke filtering core, a tubular body of air-permeable material around the core, and an outer wrapper engaged around the tubular body and providing in use for the lateral ingress of external air there through into the tubular body.


BACKGROUND OF THE INVENTION

In such concentric core cigarette filters, it is usually preferred for the core and tubular body to be of different materials, but this can give an unacceptable and unsightly end appearance to the final filter cigarette product, and it is thus conventional for the concentric core filter to be employed in conjunction with a plain buccal end plug of acceptable uniform end appearance.


SUMMARY OF THE INVENTION

According to the present invention, the core of a concentric core filter comprises a plurality of longitudinally aligned plugs of which one is an unwrapped buccal end plug of material which is the same as or similar to that of the surrounding tubular body so as to give a substantially uniform or integral or unitary buccal end appearance--i.e. no boundary between core plug and tubular body is evident at the buccal end; this may be so even during or after smoking. The filter according to the invention thus provides the required desired end appearance without the use of a separate buccal end plug which extends over the full filter cross-section and which in the prior constructions tends to mask or dilute the desirable performance and characteristics provided by the concentric core construction.
Preferably, the buccal end core plug and the surrounding tubular body are of gathered and bonded cellulose acetate tow. It is not essential for the tows of the buccal end core plug and surrounding tubular body to be identical, it being possible to obtain a uniform buccal end appearance when the two tows differ, for example, in filament or tow denier.
The invention also provides a ventilated cigarette filter having a tobacco smoke filtering core comprising a plurality of longitudinally aligned plugs, a tubular body of air-permeable cellulose acetate tow around the core, and a ventilating outer wrapper engaged around the tubular body, one of the core plugs being a non-wrapped plug of cellulose acetate tow.
The choice of the core and tubular body components and the ventilation employed may be such that in use the majority of the smoke stream passes to the smokers mouth along the core and the majority of the ventilating air drawn in through the outer wrapper passes to the smokers mouth along the region between core and outer wrapper; this may be so even when smoke enters both core and tubular body at the upstream end, and is directed from tubular body to core by the ventilation further downstream.
The outer wrapper may be perforate and/or of air-permeable material to provide for the passage of ventilating air there through. The outer wrapper may be the tipping overwrap by means of which the filter is incorporated in a filter cigarette, in which case it will usually be of air-impermeable material with ventilating perforations therethrough; the filter will then be initially produced and supplied for filter cigarette manufacture as a rod without an outer wrapper, and the present invention also includes such unwrapped rods. Instead, the outer wrapper could be one applied during filter manufacture, and extend only the length of the filter; in such cases the filter might be incorporated in a filter cigarette by means of ring tipping or of a ventilating tipping overwrap. The present invention includes all of these types of filter cigarette.
The core plugs may be of any of a variety of tobacco smoke filtering materials. The buccal end plug, which is non-wrapped, is preferably of cellulose acetate tow, but could for example be of bonded or unbonded staple fibres or other filamentary tow (e.g. of polyolefin etc.), or smoke-permeable cellular material. The buccal end core plug is accompanied by at least one other plug in longitudinal alignment therewith; suc

REFERENCES:
patent: 4064791 (1977-12-01), Berger
patent: 4301816 (1981-11-01), Wahle et al.
patent: 5012829 (1991-05-01), Thesing et al.
patent: 5107863 (1992-04-01), Nyffeler et al.
patent: 5365951 (1994-11-01), Arterbery et al.
patent: 5423336 (1995-06-01), Mentzel et al.

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