Chemical upgrading of filters
AssigneeNovapharm Research (Australia) Pty Ltd
InventorSteven Kritzler
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Abstract
The invention provides a filter treated with a humectant which may optionally be in combination with a surfactant. The treatment may also include a water soluble rheology modifier to alter the viscosity of water drawn onto the filter by the humectant. A tackifier may also be added. The invention also provides compositions suitable for application to a filter to carry out the treatment. The invention provides a method of “upgrading” a filter using the treatments and compositions described.
Claims16
1 a filter treated with a humectant.
2 A filter according to claim 1 further treated with a humectant in combination with a surfactant.
3 A filter according to claim 1 or claim 2 further treated with a water soluble rheology modifier selected to alter the viscosity of water drawn onto the filter by the humectant.
4 A filter according to any one of the preceding claims further treated with a tackifier which increases tackiness on the filter
5 A composition suitable for application to a filter comprising:
- a humectant, and
- a surfactant.
6 A composition according to claim 5 further including one or more rheological additives or tackifiers.
7 A composition according to any one of claims 5 to 6 wherein the humectant is selected from the group consisting of calcium chloride, glycerol, sorbitol, ethylene glycol, PEG, propylene glycol, 1,3-butylene glycol, PCA (2-Pyrrolidone-5-carboxylic acid), sodium sulphate, sodium hydroxide, lactic acid and derivatives thereof, sodium chloride and sodium dioctylsulphosuccinate.
8 A composition according to any one of claims 5 to 7 wherein the humectant is calcium chloride
9 A composition according to any one of claims 5 to 8 wherein the surfactant is a fluoro surfactant.
10 A composition according to any one of claims 5 to 9 wherein the rheological modifier is one or more compound selected from sodium carboxymethylcellulose;
- hydroxyethylcellulose;
- hydroxypropylcellulose;
- polyethylene glycols;
- polypropylene glycols;
- polyvinyl alcohol;
- polyvinyl acetate, polyvinylpyrrolidone and copolymers of these, hydroxypropyl guar, xanthan gum, chitosan, acrylated copolymers, polyacrylic polymers (carbopols), water soluble polymers, and water soluble copolymers.
11 A composition according to any one of claims 5 to 10 wherein the rheological additive is vinyl ether/maleic anhydride copolymer.
12 A filter when treated with a composition according to any one of claims 5 to 11.
13 A filter according to claim 12 wherein the filter is composed of a fiber selected from the group consisting of polypropylene, viscose, rayon, cellulosics, and glass fiber.
14 A method of “upgrading” (as herein defined) a filter including the step of treating the filter with a composition according any one of claims 5 to 11.
15 A method of gas filtration including the step of passing a gas to be filtered through a filter whereof the filter efficiency has been upgraded by treating the filter with a composition according to any one of claims 5 to 11.
16 A filter substantially as herein described with reference to any one of the examples.