Gas separation: apparatus – Solid sorbent apparatus – Plural diverse separating means
Patent
1994-09-16
1996-03-05
Spitzer, Robert
Gas separation: apparatus
Solid sorbent apparatus
Plural diverse separating means
96147, 96153, 553854, 55514, 55DIG5, B01D 2905, B01D 5304
Patent
active
054963966
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an ostomy filter which allows gas to be vented from colostomy and ileostomy bags, whilst at the same time filtering out any unpleasant smell, particularly hydrogen sulphide.
BACKGROUND
After undergoing a colostomy or ileostomy operation, the patient is fitted with a disposable bag which receives the waste contents of the intestine. The bag is disposable and is emptied or replaced at regular intervals. To avoid the bag becoming over inflated by virtue of gas generated by the fermenting food matter, it is desirable to provide a vent. However, the vent requires to be filtered in order to prevent embarrassing smells being released.
It is currently conventional practise in colostomy bags to provide an activated charcoal filter in the form of a disc as the vent. For example the disc may have a diameter of 23.5 mm and be formed of activated carbon contained within a foamed polyurethane material, having polypropylene net facings on either or both sides to improve its strength and other mechanical properties. However, this conventional filter material has the significant disadvantage of being liquid-permeable, so that if the patient sits or lies down there is a significant danger of leakage of liquid through the filter onto the patient's skin or his clothing. This is particularly the case with ileostomy bags, where the bag is connected into the early part of the intestine where the food matter is largely undigested and still fermenting, and has a high liquid content. In fact conventional ileostomy bags are not provided with vents, and the filters used for colostomy bags would be quickly saturated with liquid if used for ileostomy.
A porous polytetrafluoroethylene structure containing active carbon is disclosed in our British patent application GB2242431. However, the material disclosed is insufficiently gas permeable.
It is an object of the present invention to provide an ostomy filter which mitigates these problems.
Patent specification GB 1399213 discloses a gas-permeable liquid impermeable membrane which includes finely divided high surface area carbon for the production of hydrogen peroxide.
SUMMARY OF THE INVENTION
The invention provides a gas permeable and liquid impermeable ostomy filter for colostomy and ileostomy bags which comprises a mixture of; polytetrafluoroethylene (PTFE); and particles being fused together such as to form a gas permeable liquid impermeable network of interconnected particles.
PREFERRED EMBODIMENTS
The permeable nature of the polytetrafluoroethylene (PTFE) structure results from the particulate nature of the PTFE used to form it. The baking conditions are chosen such that the PTFE particles become partially fused or sintered into an integral permeable network during baking.
A feature of the present invention is that granular type PTFE is employed as a component. As is well known, PTFE can exist in two quite different forms viz; the granular form produced by precipitation polymerisation techniques, and the powdered form produced by dispersion polymerisation processes (i.e. fine-powder PTFE). These two types of PTFE have quite different properties and have to be considered separately.
Unsintered granular PTFE generally has a crystallinity in excess of 95% as determined by differential scanning calorimetry or by infra-red techniques. The degree of crystallinity is reduced by sintering (i.e. baking), and the finished structure of the present invention will typically have a crystallinity of less than 95%, often less than 80%. An unsintered granular PTFE is available from DuPont as Grade 7A.
The average particle size of the granular-type PTFE is usually in the range 1-500, particularly 1-200, especially 1-100 microns. Depending on the desired porosity of the structure, the particles may have substantially the same particle size, or a range of varying particle sizes may be included which pack to influence the porosity of the structure. The granular PTFE may be milled or unmilled.
The comminuted porous expanded polytetrafluoro
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Allan Andrew M.
Katsakoglou Akis
Samuels Gary A.
Spitzer Robert
W. L. Gore & Associates (UK) Ltd.
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