TRADUCTION NON-DISPONIBLE

METHOD FOR PRODUCING CIGARETTE FILTERS AND THE FILTERS OBTAINED

Abrégé anglais

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ABSTRACT
The method produces cigarette or cigar filters from a
fibrous sheet comprising a mixture of artificial fibers such as fibers
of cellulose acetate and fibers of natural cellulose. Artificial fibers
capable of being plasticized are employed, a specific plasticizer of
the material constituting said fibers is applied on this layer. This
plasticizer creates, after the shaping of the sheet into a cylindrical
roll, an interfiber connection network in the artificial fibrous texture
of the sheet on which there is superposed a second interfiber connection
network between the contacting zones of the sheet shaped into a fil-
tering roll.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for producing cigarette filters comprising
starting with a filtering fibrous sheet which comprises a mixture
of artificial fibers capable of being plasticized and natural
cellulose fibers, impregnating said sheet with a specific
plasticizer of the material constituting the artificial fibers,
allowing said plasticizer to start its action on the artificial
fibers, and thereafter shaping said impregnated sheet into a
roll before the end of the plasticization so as to ensure that
said plasticizer exerts its action in a further way and achieves
a double interfiber connection network namely a first interfiber
connection network within the artificial fibrous texture of the
sheet and a second interfiber connection network which is
superimposed on the first network and is produced between the
zones in contact of the sheet when it has been shaped into
said filtering roll.
2. A method as claimed in claim 1, comprising using
artificial fibers consisting of fibers of cellulose diacetate.
3. A method as claimed in claim 1, wherein the
dimensions of the artificial fibers are in the neighbourhood
of the dimensions of the fibers of natural cellulose.
4. A method as claimed in claim 1, wherein the
percentage of artificial fibers in the sheet is about 20 to 30%
by dry weight relative to the fibrous mixture, the remainder
consisting of 80 to 70% of natural cellulose fibers.
5. A method as claimed in claim 2, wherein the
plasticizer is glycerol triacetate.

Description

0~Z~32
The present invention rela-tes to a method for producing
cigarette or cigar filters from a f;brous sheet comprising a mixture
of artificial fibers such as cellulose aceta~e and fibers of na~ural
cellulose.
Filtering fibrous materials in the form of a sheet are
known which are employed after a suitable transformation for producing
cigarette filters and comprise a certain proportion of thermofusible
fibers For the purpose of lmparting to the cigarette Filters, after a
heat treatment of said material, mechanical properties of standing up
well to the efFect of smoking while remaining highly suitable for the
inhalation of the smoke by the smoker.
Other filtering fibrous materials in the form of a sheet
. are known for producing cigarette filters in the form of superposed
mult;ple layers, some of which are formed by natural cellulose fibers
. 15 such as cellulose wad, and the others are formed by cellulose acetate
for the purpose of producing, cheaply, filters having characteristics
equivalent to those of the:so-called multiple cigarette filters, that
:: is to say filters comprising a plurality of elements of different type
assembled in end-to-end relation.
~ 2Q : These two filtering fibrous materials have as respective
:~ ~ drawbacks :
the first, the drawback of requiring one or more high
temperature heating devices for bringing the whole of the filtering
mass to the temperature of fusion of the thermofusible fibers,
: ; 25 the second, the drawback o~ essentiallyirequiring the use
. of t~o layers of m~terial of very different type, for example a layer of
cellulose wad and a layer of cellulose acetate, requiring for each of
the two layers elaborate pretreating operations which are awkward and
complex to carry out
30 ~ The present invention permits overcoming these drawbacks
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and relates to a method for producing cigarette filters from afiltering fibrous sheet comprising a mixture of artificial
fibers and natural cellulose fibers.
According to the present invention there is provided
a method for produeing cigarette filters comprising starting
with a filtering fibrous sheet which eomprises a mixture of
artifieial fibers eapable of being plastieized and natural
eellulose fibers, lmpregnating said sheet with a speeific
plasticizer of the material eonstituting the artificial fibers,
allowing said plasticizer to start its aetion on the artifieial
fibers, and thereafter shaping said impregnated sheet into a
roll before the end of the placticization so as to ensure that
said plasticizer exerts its action in a further way and achieves
a double interfiber connection network, namely a first inter-
fiber connection network within the artificial fibrous texture
of the sheet and a second interfiber connection network which
is superimposed on the first network and is produeed between
the zones in contact of the sheet when it has been shaped into
said filtering roll.
In one embodiment, the proportion of the artificial
fibers comprises fibers of cellulose diacetate, the plasticizer
used being, in this case,~glycerol triacetate.
The sheet of fibrous material may be obtained by a
eonventional paper-making method or also by the well-known
technique of non-woven products. It may be employed craped or
uncraped. In the first case, the craplng may be carried out
on a paper-making machine or outside the machine.
The eellulose acetate fibers in the mixture of the
fibrous sheet may come from cuttings of short length, for example `
of 5 to 25 mm, of endless filaments of cellulose acetate which
are curled or uncurled eonstituting the "core" or "cable"
commonly employed in the construction of cigarette filters of
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acetate.
In a preferred embodiment, the acetate fiber.s in the
composition of the sheet represent 25% by dry weight relative
to the total fibrous mixture, the remainder consistiny of 75%
of natural cellulose fibers.
This fibrous sheet is in the form of reels and its
transformation in accordance with the invention, prior to its
shaping into cigarette filters, requires the ~ollowing steps:
unwinding from the reel,
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moistening of the sheet with water if necessary, ~epend-
ing on the quality of the product to be obtained,
imparting a wafer relied configuration in the form of
fine longitudinal grooves or 1engthwise craping,
possibly drying,
application by any of the means known in the fleld of
the production of acetate filters~ for example by spraying of a specific
plasticizer of the material constituting the artific;al fibers employed
in the sheet , in the case of cellulose acetate fibers~ the plastici~er
used may be glycerol triacetate and its proportion is necessarily lower
than 20 % relative to the total weight of the filter to be obtained.
. The fibrous sheet thus impregnated with plasticizer is
shaped, geometrically or in a random manner, into a filtering cylin-
drical roll, the plasticization commencing as soon as the plasticizer
is deposited on the sheet and continuing well beyond the shaping u~
the sheet, which creates, on one hand, an interfiber connection network
in the artificial fibrous texture of the sheet, and~ on the other, an
interfiber connection network between the faces, contacting zones or
.~ points of the sheet shapeo into a roll.
The present invention results in the following advantages
as concerns the cigarette filters obtained: .
good compactness and good elasticity before and during
the smoklng operation, owing to the presence of the two interfiber
connection networks which, owing to their rigidity and their lack of
~S sensit;vity to the moisture of the tobacco smoke and ~he saliva o~ the
smoker, actively participate in the reinforcement o-F the framework
of the filter,
: : good retention of the tars and the nicotine of the
tobacco smoke, owing -to the high proportion of natural cellulose fibers,
selective retention of certain toxic products of the
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tobacco smoke, such as the phenols owing to the presence of the plas-
ticizer chosen for this purpose, for example the glycerol triacetate,
improvement of the organoleptic properties of the to-
bacco smoke after its passage through the f;lter, in particular in the
case of "flue cured" tobacco owing to the ~resence of cellulose acetaté
in the sheet.
Thus the filter according to the invention combines the
: . advantages of a conventional cigarette filter of paper and the advan-
tages of a filter of acetate while limiting the respective drawbacks of
these two types of filters.
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