Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
i --~
3~:~96
~ his invention relates to a -filter for use in
venting a colos-tomy or ileostomy bag, and a me-tllod
of making such a filter.
When co:lostomy and ileostomy bags are uscd tllere
is often a build up of flatus and it is desirable to
include some means for releasing this. IIowever, i-f a
vent is provided it should also include a means for
removing the unpleasant odours from the flatus. A
number of ways of achieving this have bee~ proposed
in the past, including the use ol a Lilter containing
carbon particles or granules on a suppor-t. A disadvantage
of this type of fil-ter is -that a long pathway is nee(led
through the carbon for the filter to be effective.
According to the present invention there is provided
a filter for a colostomy or ileostomy bag, which comprises
a first layer of material which is gas permeable and water
impermeable and forms the gas inlet side of the filter,
a second layer of material which is gas permeable or is
rendered gas permeable by thepresence of at least one
aperture therethrough, and a layer of carbon cloth sandwiched
be-tween the said first and second layers, the said -first
and second layers being secured -to the carbon clo-th by a
weld which extends -through the periphery of the carbon
cloth.
According to the present invention there is also
provided a method of making a filter for use in venting
a colostomy or ileostomy bag, wherein an assembly
1 ~ n
z~
comprising a ~irst sheet of a gas permeable and wa-ter
impermeable material, a second sheet of material which
is gas permea'ble or is rendered gas permeable by the
provision of at least one aperture therethrough, and a
shee-t of car'bon aloth 'between the :Eirst and second shee-ts
is Eed to a sealing station where the assembly of sheets
is sealed together by a weld extending through the
periphery of the car'bon cloth to form a filter comprising
two pieces of the said -first and second sheets wi-th
a piece of the said carbon clo-th sealed therebetween,
and the filter is removed from the remainder of the
said assembly.
In the accompanying drawings:
Fig. 1 is an exploded perspective view of one
embodiment o-f a filter according to the invention
in position OIl a colos-tomy or ileostomy bag;
Fig 2 is a similar view o:~ a second embodiment
of filter; and
Fig. 3 is a diagra~natic view of an apparatus
for carrying out a method according to the invention
of making the filter shown in Fig. 20
The filter shown in Fig. 1 comprises on the gas
inlet side thereol' a film 1 of material which is gas
permeable 'but wa-ter impermea'ble, such as a form of "Tyvek",
which, in use, -fits directly over a vent 2 in a I'ace of the
'bag 3 (part o~ which is shown). The name "Tyvek" denotes a
range of spun-bonded plastics materials, some of which
- -~T~Je ~ k
1 m
.. . .
Z~L9~
are impermeable to water and some ot which are not,
A carbon cloth 4 wllich is placed on the "Tyvek" layer 1
covered by another film 5 also of "Tyvek" ~ ich is gas
permeable and may or may no-t be ~ater imperllleable.
Alternatively the film 5 may be O:r gas impermeable
material in which case it is provided with at least
one aperture therethrough, An ou-ter layer 7 is u~ed
to secure the filter to the outside O:e the bag 3.
The means Eor securing -the fil-ter to -the bag may
either be a layer 8 of adhesive (as illustrated),
or it may be a weld if the outer layer is made of a
suitable material such as polyvinylchloride or poly-
vinyldichloride, IE -the outer layer is so arranged
that is covers allthe carbon filter i-t i9 necessary
to provi~le a suitable area of it, with perEorations 9,
unless the outer layer is of a gas permeable material,
In the la-tter case the iilm of which the outer layer
is made is at least as permeable and preferably even
more gas permeable than the film which fi-ts directly
over the vent. Alternatively, the outer layer may just
be a meansofsecuring the ou-ter edge of -the filter to the
bag, for example an adhesive annular ring.
The layers lt~ and 5 are secured together by an
annular weld ~hich passes through -the layer 4 a-nd
extends to the periphery thereof, The fact that the
weld extends to the peripllery of the layer of carbon
lm ~ ~ -
~ - -
9~
cloth 4 means that once the weld is ormed the risk of carbon
cloth fraying from the edges thereoL is much reduced. A method
of achieving a comparable result with the embodiment of
Fig. 2 is describe~l below with reference to Fig. 3 ancl
this is appl:ica'ble with appropriate modiications to
Ihe embodiment of Fig. 1.
The filter shown in Fig. 2 comprises a layer of
carbon cloth 14 sandwiche~'between two layers 11 and 15
of "Tyvek". Between the layer 11 and the bag 3 is a film
of polyethylene 17 having a layer 18 of adhesive thereon.
The layers 11,14,15 and 17 are secured together by
concentric annular welds 19 and 19l. Although the welds
are indicated by lines they would in prac-tice have a
finite width, and the weld 19' extends to theperiphery
of the layers 11,14,15 and 17.
Fig. 3 shows a method of mal~ing the fil-ter illustrated
in Fig~ 2. A double sided silicone release paper 20
having the layer 18 of double sided adhesive transl'er tape
thereon is unwound Irom a roll 21 thereof~ The polyethylene
film 17 is -unwound from a roll 22 thereof. The film 17 and
layer 18 are brought together and travel -toge-ther beneath
a reciprocatable punch 23 which punches circular holes
in the sheet. The sheets 11 and 15 o "Tyvek" are fed
from respec-tive rolls 2l~ and 25 ana the sheet 14 of carbon
cloth is fed between the sheets 11 and 15 rom a roll 26.
The assembly of layers 11,14,15,17 and 18 pass together
with a protective layer of release paper 29 beneath a
-5-
~ . . .
2~9~
reciprocatable heat sealing die 27 which -forms annular
seals in -the assembly. 8ince the carbon cloth is porous,
"Tyveki' l'rom the adjacent sheets 11 and 15 passes in-to
the carbon cloth ~uring sealing so that an a~mular seal
is forlllecl~hich e~tends compk~tely througll t~le carbon
cloth. The fllters thus Eormed are punched ollt of the
assembly by a punch 28. The layer 29 forllls no part ol'
the filter and goes to waste after the die 28. The
layer 29 serves simply to prevent the weld head of the
die 27 sticking to the filter during manufacture. Means
(not shown) are provided for so adapting t~le reciprocation
speed of -the punch 23 and dies 27 and 28 to the speed
of travel of the layers 11,1~,15,17 and 18 tha-t the
se~ s produced 'by the die 2~ each surround a respec-tive
one of the holes produced 'by the punch 23, and the punch
28 accurately punches oùt the Eilter formed. Before
use the layer of release paper 20 is removed from the
filter to enable it to be adhered to a bag, as sho~n in
Fig. 2. The method of Fig. 3 avoids handling small
and inconvenien-t separate pieces of carlJon cloth ancl reduces the
risl~ cffraying oE the carbon cloth during and a:E-ter
manufacture and consequent generation of carbon cloth dust.
In a modificatioll of the method sho~n in Fig. 3
the rolls 21 and 22 are replaced by a single roll oE
polyethylene film having thereon an adhesive layer covered
by a release ~per.
~T~d~
lm - 6 ~
2~9~
Preferably, the filter is secured -to the ou-tside
of the bag, although it would alternatively be possible
to secure it -to the inside of the bag. In either case
the ~ater impermeable layer is on the gas inlet side of
5- the filter, that is to say iI the f:ilter is on the outside
O:r the bag the water impermeable layer is acljacent
the bag, whils-t if the filter is on the inside of the
bag the ~rater impermeable layer is remote from the bag.
This means that liquid from the bag cannot enter the carbon
cloth.
The vent to which the filter is secured can be on
either of the faces of the bag, but it is preferably
on the same face as the stoma hole and preferably located
above the stoma hole.
If desired, the filter may comprise a plurality
of layers of carbon cloth, the filter having alternate
layers of carbon cloth and material which is gas permeable
or rendered gas permeable by the presence of apertures
therethrough.
.20 An example of a suitable carbon cloth is disclosed
in U.K. Patent ~pecification No. 1,301,101. I-t is to be
understood that the term "carbon cloth" as used herein
refers to an activated carbon cloth which may be woven
or non-woven.
lm _ 7 -
