Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2002-10-08
2004-02-17
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S557000, C524S576000, C524S080000, C428S035400, C027S011000, C523S102000
Reexamination Certificate
active
06693148
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to moisture control composition responsive to changes in humidity, particularly for use in odour absorbing and releasing media in a variety of applications for removing and masking odours and other volatiles caused by pets, house-hold rubbish, moulds, cigarettes, engine exhaust gases, cooking, human sweat and vegetable and animal decomposition.
BACKGROUND OF THE INVENTION
Conventionally odour control in domestic situations has been by masking with air fresheners or by cleaning of soiled surfaces to remove the source of the odour. Absorption of malodourous liquids has also had some success.
Typical of this approach is the invention of U.S. Pat. No. 5,819,688 which discloses a mat of a cellulosic fibres bound with an acrylic latex and containing a zeolite mineral. The mat is claimed to be capable of being air dried and reused. A problem is that odours are released from the pad under drying conditions or if the pad is saturated.
U.S. Pat. No. 5,891,221 discloses an odour filtration device utilising hollow wicking fibres impregnated with a permanganate and carbonate or phosphate solution. This is placed in an air stream to remove gaseous odours. The solution flows through the fibres which are placed within a filter through which the air stream flows. This is a large scale system unsuitable for a wide variety of domestic and industrial odour problems.
U.S. Pat. No. 5,944,873 discloses a gas mask incorporating a noxious gas absorber utilising activated carbon, wherein the absorbed gas displaces an odorant as an alarm signal.
Another industrial scale system is disclosed in U.S. Pat. No. 5,236,878 discloses an odour absorbent consisting of a zeolite impregnated with a catalyst component. The adsorbed materials are desorbed by heating to regenerate the absorbent. It is an object of this invention to provide a liquid, volatiles and odour absorbing device that is effective and convenient to use.
BRIEF DESCRIPTION OF THE INVENTION
To this end the present invention provides a package having at last one porous surface, and preferably being used for an absorbent device for liquid and gaseous contaminants, said package incorporating a particulate mixture formed by mixing together
a) 5 to 50% by weight of a water and/or water vapour absorbing agent
b) 10 to 60% of a water vapour absorbing and releasing agent
c) 5 to 50% of an absorbent for small molecules and/or
d) 5 to 60% by weight of an emulsion or solution of a mixture of odour masking and neutralising compounds impregnated in the particulate components and/or
e) up to 10% by weight of a water vapour activated active ingredient.
Surprisingly this device absorbs liquid and gaseous wastes in humid and dry atmosphere conditions and releases the odour masking and neutralising compounds. This effect may be due to synergistic interaction of the surfaces of the particulate blend in facilitating the absorption of water vapour and odour compounds and the release of water vapour and actives. This invention is partly predicated on the realization that water vapour has a significant influence on the release, carriage in air and perception, of gas or vapour phase molecules many of which are responsible for mal-odours. It appears that under higher relative humidity absorption of volatiles and malodorous compounds is improved and under lower relative humidity release of the odour masking compounds is enhanced. This invention finds application in any situation where humidity varies and absorption and/or release of gas or vapour phase molecules is required. The water vapour control provided by this invention is superior to that provided by silica gel and the quantity required is of the order of 10% of the weight of silica gel needed in similar applications. Thus the composition of this invention can be used in packaging electrical and electronic devices and in situations where humidity can affect the performance of machinery such as the paper feeding mechanisms in printers and photocopiers.
In particular this invention is applicable to control of odours which are generated by microbial activity and decomposition and are carried by vapours; including pet trays, nappies, room and cupboard deodorisers, coffins, caskets, cadaver bags and mausoleums, air conditioning systems, food storage and transport containers, industrial plants with volatile and gaseous materials, waste disposal containers and rubbish bins.
The present invention also lowers microbial activity of bacteria and fungi usually associated with absorbed wastes. This is apparently influenced by the reduction in available water and water vapour which in air is defined as relative humidity and this lowering of relative humidity in the air space around the device is an important condition for retarding bacterial and fungal growth. Bacterial and fungal activity is also inhibited by contact with the active compounds on the active surfaces of the absorbents and in the air space about them and on the open surfaces of putrescent materials. Thus the device of this invention is useful in slowing the growth of fungi particuarly moulds or bacteria. In tropical, humid locations moulds other fungi and even algae proliferate in closed systems like cupboards or boats. The device of this invention allows boats and cupboards to be closed and locked without encouraging wood rot, moulds and algal slimes. The water or water vapour absorbing agent is preferably a hygroscopic polymer capable of absorbing water or water vapour in large multiples of its mass which may be described as super absorbancy. A preferred class of super absorbent polymers are polyacrylate/polyalcohol copolymers such as that marketed by Cryovac which are capable of absorbing water up to 400 times their own mass. Optionally other hygroscopic substances such as calcium chloride may be included. Where the application is only to control odours in confined spaces the content of the polymer may be 5 to 20% by weight but where liquid waste is also to be dealt with the content is usually from 15 to 60% by weight.
The agent for absorbing and releasing water vapour is preferably a porous siliceous component which is preferably silicon dioxide, perlite [a dehydrated, exfoliated glassy siliceous material] and/or vermiculite [a hydrated silicate clay or montmorillonite]. These are selected on the basis of their high porosity, very large available surface area and high capillary lift. Capillary lift increases increasing surface area to volume ratio of the particles. This invention is partly predicated on the discovery that the siliceous material such as perlite interacts with the hygroscopic polymer to improve the sensitivity of the absorbent blend to changes in humidity. It appears to increase the affinity of the polymer for water and facilitates the mass flow of water vapour and volatiles into or out of the polymer.
The molecular absorbent consists of an oxygen scavenger and/or finely divided zeolite preferably clinoptilolilite, mordenite, attapulgite and/or activated carbon. The oxygen scavenger is used in situations where the oxygen present is to be removed permanently. A preferred oxygen scavenger is marketed by Cryovac in Australia under the tradename Everfresh. The Zeolite or activated carbon will absorb oxygen but is likely to release it again if the balance is not maintained. The molecular absorbent is preferably chosen for its ability to absorb nitrogen compounds such as ammonia, amines, cationic compounds and salts thereof. These compounds are the usual consequence of decomposition. However in particular applications such as controlling sulfur compounds, the molecular absorbent will be selected for its ability to absorb sulfur containing gases and vapours. Again high porosity, chemistry, binding efficacy, particle size and large available surface area are important characteristics.
For all the particulate components particle size and surface area affect performance. For the molecular absorbent in flow through applications increasing its particle size reduced the restriction of air flow
Linklater Wayne John
Tomlinson David John
Connolly Bove & Lodge & Hutz LLP
Puro-Systems PTY LTD
Sastri Satya
Wu David W.
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