FR2520594A1 - FILTERS SMOKE - Google Patents

Abstract

THE INVENTION RELATES TO A TOBACCO SMOKE FILTER. A FILTERING BUFFER 4 HAS DUCTS 8 EXTENDING PARTLY ALONG THE BUFFER FROM THE END OF THE MOUTH SIDE OF THE latter IN THE DIRECTION OF THE INPUTS 9 THROUGH THE ENCLOSURE 7 SURROUNDING THE BUFFER SO THAT THE DUCTS PROVIDE VENTILATION PERIPHERAL SEPARATE FROM THE FILTER, WHILE OTHER OPENINGS 10 IN THE ENCLOSURE COMMUNICATE INDEPENDENTLY AND DIRECTLY WITH THE INSIDE OF THE FILTER PAD TO ALLOW THE ROOM AIR TO ENTER THIS FILTER PAD AND DILUTE THE FILTERED SMOKE FROM THE BUFFER. THIS RESULTS IN AN IMPROVED TASTE BY COMPARISON WITH A CLASSIC VENTILATED FILTER.

Description

Z 520594

  The present invention relates to smoke filters for use in connection with smoking articles.

for example cigarettes.

  So far, many proposals have been made

  cigarette filters in which ventilation air can enter ducts extending to the

  filter periphery up to the mouth end of this-

  it, and used to transport the air into the mouth of the fu-

  dies without the air inside the filter mixing, little

  or more, to the tobacco smoke sucked through the filter.

  Such a filter ventilation mode can be called

  "separate peripheral ventilation".

  Peripheral ventilation filters are required to improve the quality of tobacco smoke perceived by

The smoker.

  The present invention provides a smoke filter comprising

  a rod-like buffer of filter material having at least one air duct extending along the buffer

  between a first end of the conduit opening at the end

  mouth side of the tampon and a second opening end

  at the periphery of the stamp; and enveloping means

  buffer and allowing a first stream of ambient air to enter the air duct (s) at a location spaced from the first end and allowing a second stream of ambient air to enter directly into the duct. inside

buffer.

  Preferably, the inlet of the first ambient air stream

  in the duct is independent of the entrance to the second cou-

  ambient air directly into the interior of the buffer.

  Preferably, the air duct (s) extend (s) up to

  only a short distance from the other end of the buffer

  advantageously, the envelope means, or an outer layer

  of these, under which there is a permeable layer

  air-tight, has first and second vent holes for passing through respectively the first and second air currents. Suitably, the second ventilation holes are located on a region of the periphery of the filter pad. longitudinally spaced

  of a region of it o extend the air ducts.

  Suitably, the air duct is partially defined

  or by a number of grooves in the peripheral surface

  filter buffer and by the envelope means or

  their inner layer The grooves can extend parallel

  parallel to the axis of the filter pad or may be

  There may be two sets of helical grooves in the opposite direction so that the grooves of a game cut

the grooves of the other game

  The filter material buffer may not be in one piece For example it may comprise two half-buffers abutting, in which case a half-buffer may comprise the

  grooves delimiting the air duct.

  By using a filter according to the invention on a cigaret-

  you can get a very clear improvement in taste

  of the main stream smoke compared to what one would

  when using a filter whose only mode of ventilation is

  is the separate peripheral ventilation.

  The invention will be better understood on reading the

  detailed description, given below as an example only

  1, is a partial view in axial section of a filter-tipped cigarette, FIG. 1a is a cross-sectional view of a half of the cigarette. of Figure 1, taken along the line

A-A,

  FIG. 2 shows a filter pad of another shape than that of the cigarette of FIG. 1, and FIG. 3 shows, partially in axial section, a

other form of filter pad.

  The cigarette of FIG. 1 comprises a roll 1 of

  cut tobacco surrounded by cigarette paper 2, and a filament

  3 having an individual filtering pad 4 of fibrous filtering material based on cellulose acetate.

  grooves 5 (see also Figure la) extends to the

  The grooves 5 open out at the mouth end of the tampon 4 and extend parallel to the axis of the tampon over approximately half of its length.

  suitable for forming the grooves 5 is to subject the drum to

  4, or preferably a length of filtering flange from which several buffers 4 will be cut, to a hot molding process, for example that described in British Patent No. 1,507,765. The sealing of the walls of the grooves 5 can be ensured. by applying to them an impermeable material, by

example of polyethylene.

  A sleeve 7 serves to fix the filter 3 on the flange

  1,2 In the parts where it covers the reas-

  5, the sleeve 7 defines, in connection with the walls of the grooves 5, air ducts 8, two rows of ventilation holes 9 and 10 are provided in the sleeve 7. As shown in FIG. 9 holes surrounds

  buffer 4 in the portion thereof in which extends

  grooves 5, the arrangement being such that at least one of the holes 9 communicates with each of the air ducts 8 The row of holes 10 surrounds the portion of the sleeve 4 in

  which do not extend the grooves 5.

  If desired, the holes 9 and 10 can be formed

  in the form of microperforation zones of the cuff 7.

  It is also possible that the cuff 7 covers

  an air permeable buffer envelope, in which case the man-

  chette serves as an outer layer in which are spared

the ventilation holes.

  An alternative is that the sleeve 7 covers an impermeable pad envelope, in which case the shell itself must have holes corresponding to the holes 10 of the sleeve 7. Suitably, in the latter case, the holes the envelope of the pad are formed together with the holes 10, mechanically or by laser drilling. When smoking the cigarette of Figure 1, ambient air is sucked through the holes 10 directly into the filter pad 4 and mixes with tobacco smoke passing through the latter. Ambient air is also sucked in. separately through the holes 9 in the air ducts 8 and passes along the ducts to their outlet ends

  without mixing, more or less, with the smoke.

  The filter pad shown in FIG. 2 and generally indicated at 11, is a buffer that can be used in place of the pad 4 of FIG. 1. The pad 11 comprises a number of equidistant longitudinal grooves 12 which open at the end. mouth side of the tampon and

  extend significantly less than the length of time

  The buffer portion of the buffer portion 11 does not show

  not only the longitudinal grooves 12, the buffer comprises

  a deep annular circumferential groove 13 The grooves

  The longitudinal ribs 12 and the circumferential groove 13 may suitably be formed by a hot molding process. When the pad 11 is incorporated in a filter-tipped cigarette, it is surrounded by an envelope made of

  to allow a first flow of air to enter directly

  in the air ducts bounded by the walls of the walls.

  longitudinal nines 12 and the surface looking towards

  the inside of the envelope, and a second stream of air separated

  to penetrate the circumferential groove 13 The second

  the current of air enters directly into the interior of the buffer 11, mainly through the downstream side wall

of the circumferential groove 13.

  If a cuff surrounding the filter pad 11 is

  provided with a row of holes (such as holes 9 in the

  1) in correspondence with the portion of the buffer in the

  which extend the longitudinal grooves 12, and if

  some intermediate holes in this row are available

  Between the longitudinal grooves, the air can be prevented from penetrating into the interior of the pad 11 through these intermediate holes by applying an impermeable ageri to the peripheral surface of the pad 11 Alternatively, the pad 11, or a length of filtering flange which is initially part of the buffer 11, may be surrounded by an impermeable envelope of thermoplastic nature before

  to be hot-molded to provide the longitudinal grooves

  In the latter case, the hot molding of the relatively shallow longitudinal grooves 12 leaves the impermeable envelope substantially intact, while little or no remains of

  the envelope in the deep circumferential groove 13.

  Thus, the walls of the longitudinal grooves 12 are imper-

  air-permeable and at least the side walls of the throat

  circumferential are permeable to air.

  FIG. 3 shows another form of filter pad generally identified at 14, which can be used in place of the stamp 4 of FIG. 1. The pad 14 comprises a number of equidistant helical grooves 15 which extend from the mouth end of the tampon 14 and can be formed by a hot molding process.

  buffer 14 has, where there is no reason to

  15, a number of holes 16 extending radially

  inwards from the peripheral surface of the drum.

  The holes 16 can be formed mechanically or by

  laser, the formation of the holes taking place

  after mounting the tampon 14 on a cigarette roll, so that the formation of the holes 16 also causes the

perforation of the envelope.

  Although the filter pads described above are

  in one piece, buffers can be used in two parts.

  such that a first member has grooves extending from the mouth end of the first member and the second member has means to allow air to enter the interior of the second member.

  grooves of the first element may extend over its entire length

  If such two-piece buffers are wrapped in respective pad envelopes, suitably the shell of the first member is impervious to air, while

  that that of the second element is permeable to air.

  The air / smoke regime coming out of each of the filters described

  above, provided that it is due to the peripheral ventilation

  separated, is modified by the establishment within

  filter of an air / smoke current due to direct penetration

  Ventilation air inside the filter pad.

  The effect of this modification unexpectedly improves the

  taste of mainstream smoke.

  The various holes 9, 10 and 11 shown in the drawing are not to scale and their size has been extruded to

for illustration purposes.

2 2 059 4

Claims (1)

1 Smoke filter comprising a rod-like pad of filter material having at least one air duct extending along the pad between a first end of the duct leading to the mouth-side end of the drum. pon and a second end opening at the periphery of the buffer, and a casing surrounding the pad and allowing an asbestos air flow to enter this (s) air duct (s) at a location spaced from the second end, characterized in that the holes (10) in the envelope (7) allow a second flow of ambient air to enter directly into the interior of the buffer (4). 2 Filter according to claim 1, characterized in that the arrangement is such that the inlet of the second ambient air stream is independent of the inlet of the first ambient air stream. 3 Filter according to claim 1 or claim 2, characterized in that the second end of (the) duct (s) of air is between the ends of the buffer (4) and is spaced therefrom. 4 Filter according to any one of claims 1 to 3, characterized in that the casing is generally permeable to air, but has a less permeable outer layer having the first vent holes mentioned for passing the second stream of ambient air. Filter according to any one of the preceding claims, characterized in that the air duct (s) 8 extend (ent) over a first region of the buffer (4) and that the ventilation holes (10) ) are located on a second region of the buffer periphery which is spaced longitudinally from the first region. 6 Filter according to claim 5, characterized by a circumferential groove (13) in the buffer (4) in this second region, this groove (23) corresponding with the authorized inlet of the second ambient air stream and for directly admitting the second filter in the interior of the buffer (4) 7 Filter according to any one of claims 4 to 6, characterized in that the envelope (7) has zones of microperforations, one of which defines the holes of ventilation and the other allows the entry of the first current of ambient air through the envelope. Filter according to any one of the preceding claims, characterized in that there is a multiplicity of grooves (5) equally distributed around the periphery of the plug (4) and in that the air ducts (8) are partially defined by these grooves (5) and also partially by the radially inwardly facing surface of the envelope (7). 9 Filter according to any one of the preceding claims, characterized in that the buffer (4) comprises two half buffers in abutment, one of the half-buffers comprising at least one air duct (8) and the the other being devoid of air ducts. Filter according to any one of the claims   1 to 9, characterized in that the air duct (s) (8)   turns around the filter pad (4)   from the mouth end of the tampon.