Photocatalytic compositions and methods

Details Photocatalytic compositions and methods Photocatalytic compositions and methods

2000-12-21

2003-11-11

Markoff, Alexander (Department: 1746)

Cleaning and liquid contact with solids

Processes

Using solid work treating agents

C134S004000, C134S007000, C252S182320

Reexamination Certificate

active

06645307

ABSTRACT:

The present invention relates to photocatalytic compositions and in particular, but not exclusively, to photocatalytic cleaning compositions, intended to reduce the frequency and/or effort of cleaning; and to methods employing such compositions. References will be made herein to cleaning compositions and/or to compositions which are effective in combating malodours and/or soils and/or microorganisms, these being preferred compositions, but descriptions and definitions which follow are applicable also to compositions intended for other purposes.
Cleaning compositions of the invention are of particular interest for cleaning surfaces such as ceramic tiles, sinks, baths, washbasins, toilets, worksurfaces, ovens, hobs, carpets, fabrics, floors, painted woodwork, metalwork, laminates, glass surfaces and the like.
Cleaning compositions intended for general and for specific uses are well known in the art. Such compositions, when liquid, will commonly comprise one or more surfactants, to loosen and/or disperse oily deposits and to dissolve water soluble materials. These cleaning compositions may include one or more of solvents (including water), thickening agents, abrasive particles, bleaching agents, disinfectants/antibacterial agents, perfumes, waxes or other polishing agents, preservatives, colouring agents and like additives. The liquid formulation provides a vehicle for the removal of insoluble particulate matter and builders and suspending agents are often included in the compositions to facilitate this process. These prior art compositions are, to a greater or lesser extent, effective in removing soils, usually organic soils, from surfaces and in preventing their redeposition during the cleaning process. However, re-soiling of the surfaces after cleaning is an inevitable and continuous process.
Thus, domestic and other surfaces are continually dirtied or soiled by various means including, for example, soiling resulting from the preparation of food, contact by people and domestic pets, deposition of oily deposits and of airborne materials. Not only are these and like soils aesthetically displeasing, they may also have deleterious effects on health. The soils may contain allergenic material such as pollen, dust mites, dust mite droppings, cat and other animal allergens and furthermore may include harmful or toxic materials derived from adjacent or nearby industrial, horticultural or agricultural processes. Deposited soils may also harbour and give sustenance to pathogenic microorganisms or might include residues of human or animal faeces or urine. It is therefore important that these and like deposited soils are removed from surfaces efficiently and frequently.
Cleaning of surfaces is therefore a frequent and often time consuming requirement and is inevitably regarded as an unpleasant chore. There is a need for means to reduce the frequency of cleaning, and desirably also to facilitate the removal of soils deposited on surfaces. It will be appreciated that known, conventional, cleaning compositions have no effect on soils deposited on the surfaces after the cleaning process until such time as the cleaning process is undertaken again. The present invention therefore seeks to provide cleaning compositions which, after the cleaning process, are effective to reduce the required frequency of cleaning and/or to facilitate the removal of deposited soils.
It is an object of embodiments of the invention to provide a composition showing improved photocatalytic action.
In accordance with a first aspect of the present invention there is provided a composition which comprises in admixture a photocatalytic material or a precursor to a photocatalytic material, and a sensitiser which acts to absorb visible or ultra violet or infra-red radiation and enhance the photocatalytic action of the photocatalytic material.
It is an object of embodiments of the invention to provide a cleaning composition which, in addition to combating existing malodours and/or soils and/or undesired microorganisms when applied to a locus, for example a surface, combats further malodour compounds and/or soils and/or undesired microorganisms, after its application to a locus.
In accordance with a second aspect of the present invention there is provided a composition comprising a photocatalytic material able to combat malodours and/or soils and/or undesired microorganisms at a locus, or a precursor to such a photocatalytic material, and a sensitiser which acts to absorb visible or ultra-violet or infra-red radiation and improve the efficacy of the photocatalytic material in combating malodours and/or soils and/or undesired microorganisms at the locus.
By “combat” we mean that the composition of the second aspect can be used to remove and/or break down malodour compounds and/or soils and/or microorganisms at the locus and/or it can prevent malodours and/or soils and/or microorganisms from building up at the locus. The term “microorganism” is used in this specification to denote any microscopic organism which is combatted; but especially a bacterium. Also of interest, however, as microorganisms which are prospectively combatted by compositions of the invention, are viruses and fungi, in particular yeasts. One pathogenic microorganism which is of particular interest as demonstrating the efficacy of the compositions of the present invention is the bacterium Staphylococcus aureus.
Said composition of the second aspect includes deodorising compositions and anti-allergenic compositions. For example the compositions may have a deodorising effect, by breaking down odoriferous compounds, as deposits and/or as airborne compounds. For such uses the compositions may be applied to surfaces in the appropriate location or may be used in room sprays.
By means of the present invention a residue or layer of photocatalytic material can be provided at a locus, for example on a surface whereby soils and/or undesired microorganisms deposited on the residue or layer or soils or undesired microorganisms which are present on the surface prior to deposition of the residue or layer are subject to a photocatalytic or other photochemical oxidation, reduction, free radical or other photochemical reaction effective to break down, “burn away” or otherwise decompose the soils or undesired microorganisms or at least major components thereof; and/or to weaken their contact with the surface. Consequently it may be said that the cleaning process continues after the conventional act of removal of the soil or undesired microorganisms is completed.
As noted above soils may contain allergenic material which is decomposed or otherwise degraded by means of the present invention. Of particular interest is the use of the compositions of the invention in combating allergenic soils associated with house dust mites.
It is believed that the faeces of two particular house dust mite species,
Dermatophagoides farinae
(known as Der-f) and
Dermatophagoides pteronyssinus
(known as Der-p) trigger the immune responses of the body, thereby giving rise to well known allergenic responses.
A review of this is given in Experimental and Applied Acarology, 10 (1991) p. 167-186 in an article entitled “House dust-mite allergen”, a review by L. G. Arlian.
Both the Der-f and Der-p species are found throughout the world. In some areas, Der-f will be the sole Dermatophagoides species. In other areas Der-p will be the sole species. In still other areas, the two species are both present through, generally, one or the other will predominate.
Using the photocatalytic material, a decomposition reaction undergone by a malodour compound or a soil may involve photo-induced oxidation and/or photo-induced reduction reactions with organic or inorganic components of the malodour compound or soil. These reactions may in turn result in the production of free radicals which are effective in breaking down organic matter in the malodour compound or soil. These reactions may also provide an ongoing benefit after the initial deodorising or cleaning process has been completed.
One suitable photocatalytic mater

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