WO2007012106A1

WO2007012106A1 - Sacrificial anti-graffiti coating composition

Info

Publication number: WO2007012106A1
Application number: PCT/AU2005/001854
Authority: WO
Inventors: Ernie Aykut
Original assignee: Biobarrier Pty Ltd
Priority date: 2005-07-29
Filing date: 2005-12-12
Publication date: 2007-02-01

Abstract

A sacrificial anti-graffiti surface coating is prepared from at least one lower saccharide as defined and water or beeswax and an organic solvent as defined.

Description

SACRIFICIAL ANTI-GRAFFITI COATING COMPOSITION

TECHNICAL FIELD

The invention relates to a surface coating, which may be used as a sacrificial anti-graffiti surface coating.

DESCRIPTION OF PRIOR ART

The application of graffiti in the form of words, lettering, pictures and the like to exposed and unprotected surfaces such as buildings, walls, street signage, public transport and fences has become a considerable problem in many countries. Graffiti is most often applied using aerosol paint, but may be applied using other marking devices such as felt tip pens, pencils, crayons, lipsticks, markers, and the like.

Cleaning of surfaces defaced with graffiti is costly and time consuming, usually requiring special, high strength cleaning agents. Where a graffiti marking substance has penetrated a surface, such as a porous surface, removal of the graffiti requires sand-blasting. This can leave the surface damaged or scarred. Therefore, re-finishing of the surface after graffiti removal may be required, adding to the time and expense involved.

Coatings have been developed to provide a protective barrier to protect an underlying surface from graffiti applied on top of the coating, and to make graffiti removal easier. These coatings are usually sacrificial to make graffiti removal easier. The term "sacrificial" means that the coating, as well as the graffiti, is removed during graffiti removal. Therefore a new coating must be applied after each graffiti removal.

Many of the sacrificial coatings that have been developed include toxic chemicals or require the use of organic solvents for their removal. These coatings therefore, may be not only harmful to the user's health but environmentally unfriendly. The present invention provides a surface coating, which may be used as a sacrificial anti-graffiti surface coating. The sacrificial anti-graffiti surface coating is environmentally friendly and biodegradable and does not require the use of organic solvents for its removal. BACKGROUND OF THE INVENTION

US 5.017.237 Svensson (Bioboat). Films of polysaccharide can be formed on a solid surface by evaporation. In the present invention the "polysaccharides" have been restricted to "monosaccharide, disaccharide or lower saccharide". In addition in the present invention tea leaves are added to assist bonding and essential oils as an insect repellent.

US 5,418,006 Roth etc (Wacker-Chemie). It is an object of the Roth invention to provide a method for coating substrate surfaces which are not water-absorbent. Generally speaking the object of the present invention is to coat substrate surfaces with a coating which is permeable to air and water vapour and is adequately resistant to weathering. On the other hand, the Roth invention provides a method for coating substrate surfaces which are not water-absorbent, which comprises coating the substrate surfaces with an aqueous composition containing an aqueous solution, dispersion and/or emulsion of film-forming substances and water repellent substances, in which the coating can be removed again by treatment with water. Examples of particularly preferred film-forming substances are, for example, cellulose, cellulose ethers and cyclic polysaccharides, such as cyclodextrins. Examples given of a water-repellent substance are the waxes candelilla and camauba, beeswax and lanolin; mineral waxes ceresin and ozokerite and chemically modified waxes. In addition Roth does not make use of tea leaves.

US 5,948,545 Svensson (Polysaccharide Industries). The Svensson invention provides a process for protecting a surface from non-desired contamination and for facilitating removal of said contamination from the surface, said process involving the following steps :

"a) preparing a solution of polysaccharides containing at least two components, wherein one component is constituted by a first polysaccharide which, when precipitated from a solution by evaporation of the solvent thereof, directly forms a film and wherein the second component is constituted by a second polysaccharide which, when precipitated from a solution by evaporation of the solvent thereof, forms a film via at least partial gel formation, or by interaction with said first polysaccharide, said films being redissolvable or swellable; b) applying the solution from step a) onto said surface before subjected to contamination; c) allowing the applied solution to dry so as to form a solid film on said surface via at least partial gel formation; d) treating the film-coated surface with a liquid capable of redissolving the film or providing swelling thereof; and e) removing the non-desired contamination by complete or partial removal of the film from the surface." The present invention does not require the preparation of a solution containing at least two polysaccharides and proceeding from this solution to an intermediate gel and to a solid film. Such a film, for example, bearing graffiti, is fairly resistant to cold water. However, this film, graffiti or air pollution is easily removable by washing the film using water of increased temperature and/or pressurized water supplied through a nozzle. In addition, Svensson does not make use of tea leaves.

FR 2683540 Casco Nobel France. This specification concerns a process for the preparation of compositions for the prevention of graffiti. It concerns the use of synthetic waxes such as polytetrafluoroethylene (PTFE), polyethylene (PE), modified polytetrafluoroethylene by mixture or grafting, polypropylene, amorphous amides, olefin extracts from petroleum products and waxes of natural origin such as carnauba wax and beeswax. The specification states that waxes of the type PTFE-PE are "always" preferred.

The solvents which are used are butanol, isopropanol, ethanol, butyrolactone, cyclohexanone, N- methyl-pyrrolidone, dimethylformamide, butyl acetate, ethyl glycol acetate, ethoxy propyl acetate and butyl glycol. Example 1 uses PTFE-PE (originating from Lanzer SA) and naphtha solvent (originating from Esso). Example 2 uses wax of halogenated polyolefin (originating from Daniel Products Company) and naphtha solvent (originating from Esso).

Example 3 appears to use "Lanco-Wax® J but does not give a formula or composition. Although the present invention uses beeswax, the solvents are quite different ie. linseed oil and turpentine. BRIEF SUMMARY OF THE INVENTION

This invention provides a preparation for a sacrificial anti-graffiti surface coating, the preparation comprising at least one saccharide; and either in a first embodiment water or in a second embodiment an organic solvent.

In this specification the term "saccharide" means a monosaccharide, disaccharide or lower polysaccharide. When used in this specification the term "saccharide" includes these alternatives.

A preferred disaccharide is sucrose (table sugar).

Furthermore, in this specification the term "organic solvent" means linseed oil, turpentine or mixtures of these and their synthetic equivalents.

Preferably, in the first embodiment the composition comprises about 5Og to about 75Og of at least one saccharide per I of water or, alternatively, the composition comprises about 70Og of at least one saccharide per about 300ml of water.

Preferably in the second embodiment, the composition comprises about 150 to about 50Og of at least one saccharide and about 10Og to 25Og beeswax and about 500 ml to about 1 1 linseed or turpentine oil.

In the case where beeswax is used the saccharide is dissolved in linseed oil or turpentine and the solution used to dissolve beeswax. The softened film of beeswax may be applied to a surface to be protected. In the first embodiment, preferably the composition according to the invention comprises a saccharide, water and tea leaves and more preferably an insect repellent. The tea leaves help the preparation to bond to surfaces to which it is applied and are used in amounts of about 0.5g to about

15.Og per I of water and more preferably about 0.5g to about 3.Og per I of water.

Preferably, this embodiment comprises about 1.Og to about 3.Og tea leaves per I of water, and more preferably about 1.Og to about 1.5g of tea leaves per I of water.

In this specification the words "tea leaves" includes "tea dust". The tea leaves or tea dust may be selected' from a variety of black, red or green tea, or a combination thereof. In a preferred embodiment, the tea leaves are black tea leaves.

Preferably, the first embodiment comprises an insect repellent which may be a natural or synthetic essential oil. Preferred essential oils include peppermint, thyme, lavender, lemongrass, tea tree, citronella, pennyroyal, spearmint, garlic, or a combination thereof.

Preferably, the first embodiment comprises about 0.05ml to about 7.5ml, and more preferably about 0.08ml to about 2.5ml, of insect repellent.

In the first embodiment according to the invention, the sacrificial anti-graffiti surface coating is prepared by mixing the saccharide with sufficient water to dissolve it at least partially at the selected temperature. It is preferable to apply the sacrificial anti-graffiti surface coating to a surface to be protected at a temperature of from ambient to about 50^°C.

The first embodiment may also contain about 0.1 to about 1 g of citric acid per I of solution , preferably in solution form, as a binding agent.

A second aspect of this invention provides a method of making a sacrificial anti-graffiti surface coating, the method comprising mixing a mixture as defined above with the required amount of water. Preferably, the temperature of the water is from ambient to about 100°C.

Preferably, the sacrificial anti-graffiti surface coating is applied to a surface to be protected at ambient temperature.

This invention also provides in respect of each embodiment a kit comprising a preparation for a sacrificial anti-graffiti surface coating as described above, the ingredients being contained in the kit together or separately, and the kit being arranged so that the ingredients may be mixed with sufficient water or organic solvent to prepare a sacrificial anti-graffiti surface coating.

Preferably, the kit also comprises an applicator to apply the sacrificial anti-graffiti surface coating to a surface to be protected.

DETAILED DESCRIPTION OF THE INVENTION The preparation for the sacrificial anti-graffiti surface coating comprises at least one saccharide. A preferred saccharide is a disaccharide such as sucrose (table sugar) since it is economical and readily available.

The first embodiment of the sacrificial anti-graffiti surface coating or surface coating also comprises tea leaves. The tea leaves may be selected from a variety of black, red or green tea leaves, or a combination thereof. Preferably the tea leaves are black tea leaves or tea dust. The results of tests conducted with examples of sacrificial anti-graffiti surface coatings show that the sacrificial anti-graffiti surface coating remains on surfaces for longer periods of time if the preparation for the sacrificial anti-graffiti surface coating comprises tea leaves or tea dust.

Preferably in the alternative preparation for the first embodiment, for the sacrificial anti-graffiti surface coating comprises about 1.0g to about 1.5g of tea leaves or tea dust : 300ml water : 70Og saccharide. The tea leaves or tea dust may be removed from the sacrificial anti-graffiti surface coating prior to use.

It has been found that citric acid aids binding of the coating to the surface to be protected.

In the case of the second embodiment, when the solvent evaporates a layer of beeswax is left forming the sacrificial anti-graffiti surface coating.

Since the sacrificial anti-graffiti surface coating will be used typically on exposed and unprotected surfaces such as buildings, walls or street signage, which are exposed to outdoor elements, the preparation for the sacrificial anti-graffiti surface coating or sacrificial anti-graffiti surface coating also comprises an insect repellent. The insect repellent may be a natural or synthetic essential oil. The sacrificial anti-graffiti surface coating comprises at least about 0.05ml of an insect repellent.

If the preparation for the sacrificial anti-graffiti surface coating is made up as a powder, it may be packaged loose or in a tea-bag arrangement.

The prepared sacrificial anti-graffiti surface coatings, may be stored for up to 2 to 3 years, possibly longer, without degradation. The sacrificial anti-graffiti surface coating may be applied to a variety of types of surfaces including, but not limited to, porous and non-porous surfaces, treated or untreated surfaces, and painted or unpainted surfaces. Surface examples include masonry, cement, brick, mortar, plasters, stuccoes, stone, wood, metal such as stainless steel, some plastics materials, glass, varnished or painted surfaces. Depending on the condition of the surface to be protected, the surface may require some preparation before application of the sacrificial anti-graffiti surface coating, for example, pre-washing.

The sacrificial anti-graffiti surface coating may be applied to a surface to be protected by spraying, brushing, rolling or any other conventional application means.

It is also preferable not to apply the sacrificial anti-graffiti surface coating in humid conditions since this may cause the sacrificial anti-graffiti surface coating to absorb moisture from the air and dry unevenly.

The amount of sacrificial anti-graffiti surface coating needed to adequately cover a surface will be dependent on the nature of the surface to be protected. The liquid embodiment of the invention is used for porous surfaces and the paste embodiment for non-porous surfaces. One coat of paste will usually suffice for non porous surfaces. For example, a greater quantity of liquid will be be needed to provide adequate protection of a porous surface such as stucco, brick or cement compared to a non-porous surface such as a metal. Typically, however, approximately 1 1 of the liquid sacrificial anti- graffiti surface coating will adequately cover around 10 square metres of a smooth non-porous surface and around 6 to 8 square metres of a rough porous surface. On a smooth non-porous surface, at least 2 coats should be applied. On a rough porous surface, more coats may be desired or needed. Although the thickness of each coat may vary, one coat of the sacrificial anti-graffiti surface coating may typically be the same as a layer of lacquer on a smooth non-porous surface (i.e. about 1 mm). The sacrificial anti-graffiti surface coating will dry relatively quickly after application.

Once applied to a surface, the sacrificial anti-graffiti surface coating forms a substantially transparent protective layer or barrier on the underlying surface. Thus, any graffiti markings will not contact or penetrate the underlying surface. The sacrificial anti-graffiti surface coating will also not detract from the appearance of the surface of the building, artistic work, signage and so on to which it may be applied.

The liquid embodiment of the surface coating should be an effective protective barrier for at least 2 to 3 months, possibly less if the surface is exposed to harsh weather conditions but up to 2 years if not exposed to the elements. In such conditions, it is preferable to re-apply the sacrificial anti-graffiti surface coating at regular intervals to ensure that it remains an effective protective barrier. The paste embodiment will last for a minimum of 2 years.

If graffiti markings are applied to a surface coated with the sacrificial anti-graffiti surface coating, or if the sacrificial anti-graffiti surface coating becomes excessively soiled, the graffiti and/or soiling can be removed. Removal of the graffiti and/or soiling will also remove the sacrificial anti-graffiti surface coating. The sacrificial anti-graffiti surface coating, and the graffiti and/or soiling, may be removed by the use of high pressure water. Preferably, cold water is used during the removal process. Removal of the sacrificial anti-graffiti surface coating, graffiti and/or soiling will not cause any damage to the underlying surface. After removal of the graffiti and/or soiling, together with the sacrificial anti-graffiti surface coating, a new sacrificial anti-graffiti surface coating may be applied. Graffiti that may be removed with the sacrificial anti-graffiti surface coating includes markings made by such substances as spray or aerosol paints, paints, permanent inks, colour markers, felt-tip pens, ink pens, pencils, crayons, lipsticks and the like. As mentioned above, the sacrificial anti-graffiti surface coating may also protect a surface from soiling. The term "soiling" as used herein includes soiling by pollution, waste, oil sprays, sea salt and so on. However, the primary advantage of the sacrificial anti-graffiti surface coating of the present invention is that it is environmentally friendly, unlike some of the existing anti-graffiti coatings. It does not contain any toxic chemicals and is readily biodegradable. In addition, the sacrificial anti-graffiti surface coating is also quick and easy to apply, and economical for repeated usage. Since the sacrificial anti-graffiti paste surface coating is substantially transparent, it will not detract from the appearance, ie the reflective values, of the surface of the building, artistic work, signage, and so on to which it may be applied.

The invention will now be further described by reference to specific examples, which are included merely for the purpose of illustration and are not to be construed as limiting the scope of the present invention.

EXAMPLES

The following are examples of sacrificial anti- graffiti surface coatings that were tested.

Example 1 sucrose (table sugar) 70Og black tea leaves 1.0g tea tree oil 0.1ml water 300ml

Example 2 sucrose (table sugar) 70Og black tea leaves 5.Og tea tree oil 0.1ml water 300ml

Example 3 sucrose (table sugar) 70Og tea tree oil 0.1ml water 300ml

Example 4 sucrose (table sugar) 70Og black tea leaves 1.5g lavender oil 0.08ml water 300ml

Example 5 sucrose (table sugar) 700g black tea leaves 1.0g water 300ml Example 6 sucrose (table sugar) 60Og black tea leaves 1.0g tea tree oil 0.1ml water 300ml

Example 7 sucrose (table sugar) 60Og black tea leaves 5.Og tea tree oil 0.1ml water 300ml

Example 8 sucrose (table sugar) 65Og black tea leaves 1.0g tea tree oil 0.1ml water 300ml

Example 9 sucrose (table sugar) 700g black tea leaves 2.Og citric acid solution 5ml eucalyptus oil 1.5ml water 300ml

The sucrose was dissolved at boiling point in the water and the tea leaves added. The citric acid was added to improve the binding characteristics of the sacrificial anti-graffiti surface coating. The eucalyptus oil was added as an insect repellent.

Example 10 sucrose (table sugar) 18Og beeswax 12Og linseed oil 700ml The sacrificial anti-graffiti surface coatings of Examples 1 to 8 were prepared with water at a temperature of about 100°C and could be stored at ambient temperatures without affecting activity for some years.

The black tea leaves present in the sacrificial anti-graffiti surface coating of Example 6 were removed prior to application to various test surfaces.

In the case of Example 10 the sucrose was dissolved at boiling point in the linseed oil and the beeswax added. The solution was diluted with linseed oil to soften the wax providing a satisfactory sacrificial anti-graffiti surface coating. The surface coating was 100% waterproof for long periods. The various test surfaces included : - plasterboard

- poly (methylmethacylate)

- other plastics materials aluminium

- stainless steel - corrugated iron glass

COLOURBOND® pre-coated metal sheeting

- lacquered surfaces painted surfaces It was found that the sacrificial anti-graffiti surface coating was suitable on all surfaces except untreated timber and plastics materials.

The sacrificial anti-graffiti surface coatings of Examples 1 to 9 were applied to some of the test surfaces when at ambient temperature by brushing or spraying. However, when using a spray gun it is recommended to warm and stir the sacrificial anti-graffiti coating prior to application, if fine spray nozzles are used.

Generally speaking temperature is not a problem. However, if the weather was drizzling or raining the coating tended to wash off.

Approximately 2 to 3 coats of each sacrificial anti-graffiti surface coating were applied to the test surfaces. The sacrificial anti-graffiti surface coatings of Examples 1 and 3 to 9 were substantially transparent whereas the sacrificial anti-graffiti surface coating of Example 2 was visibly discoloured. The discolouration of the sacrificial anti-graffiti surface coating of Example 2 was most likely caused by the amount of tea leaves used to prepare the sacrificial anti-graffiti surface coating. The sacrificial anti-graffiti surface coatings of each example were left on the test surfaces for periods of up to 6 months. The test surfaces were exposed to different weather conditions including light rain, heavy rain, sunshine and heat, which were either naturally occurring or artificially simulated. The test surfaces were also exposed to other outdoor elements including insects. It was found that the sacrificial anti-graffiti surface coating of Example 3 washed away from the test surfaces with light rain, which was enhanced through use of a sprinkler, over a relatively short period of time. The sacrificial anti-graffiti surface coating of Example 3 did not seem to provide a very effective protective barrier to the underlying surfaces. The sacrificial anti-graffiti surface coating of Example 7 also did not seem to provide an effective barrier to the underlying surfaces. For various reasons, none of Examples 1 to 9 displayed substantial resistance to rain or spraying with water.

However, it was noted that the sacrificial anti-graffiti surface coatings of most of the other examples, which included tea leaves or tea dust, remained on the test surfaces for substantially long periods of time. Therefore, it is reasonable to assume that inclusion of tea leaves (or tea dust) provided an adhesive property to the sacrificial anti-graffiti surface coatings. Although the sacrificial anti-graffiti surface coating of Example 5 remained on the test surfaces during the test periods, it also attracted numerous insects. It was concluded that this was a result of the absence of an insect repellent in the sacrificial anti-graffiti surface coating. After a period of time, some of the remaining test surfaces were marked with paint containing a high grade acrylic thinner. The paint was allowed to remain on these test surfaces for periods of up to 2 weeks.

The sacrificial anti-graffiti surface coatings, which remained on the test surfaces, were subsequently removed by gentle scrubbing using a soft-bristled brush dipped in a mixture of soap and water or by the use of high pressure water. The removal process removed the sacrificial anti-graffiti surface coatings together with the paint markings. There was no visible damage or scarring on any of the test surfaces after removal of the sacrificial anti-graffiti surface coatings.

The sacrificial anti-graffiti surface coatings of at least Examples 1, 2, 4, 5, 6, and 9 were shown to provide an effective protective barrier to the underlying test surfaces to which they were applied, that is, to surfaces which were protected from rain, such as the underneath of bridges, the interior of toilets, confined areas in bus and train stations. Since the sacrificial anti-graffiti surface coatings of

Examples 3 and 8 did not seem to remain on the underlying test surface for a substantially long period of time, it was concluded that the sacrificial anti-graffiti surface coatings of these two Examples did not provide an effective protective barrier. The sacrificial anti-graffiti surface coating of Example 10 was also found to remain on the underlying test surface for a substantially long period of time and so provided an effective protective barrier. The paste was found to provide a surface which was resistant to rain and thus could be used on unprotected surfaces.

It will be appreciated by persons skilled in the art that various changes and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered as illustrative and not restrictive.

Claims

1. A preparation for a sacrificial anti-graffiti surface coating, the preparation comprising at least one saccharide as defined herein and water or beeswax and organic solvent as defined herein.

2. A preparation as claimed in claim 1 , which comprises about 5Og to about 75Og of at least one saccharide per I of water.

3. A preparation as claimed in claim 1 , which comprises 70Og of at least one saccharide per I of water.

4. A preparation as claimed in claim 2 which comprises a saccharide, water and tea leaves.

5. A preparation as claimed in claim 4, which comprises an insect repellent.

6. A preparation as claimed in claim 4 or claim 5, which comprises about 0.5 to 3.Og per I of tea leaves.

7. A preparation as claimed in claim 5 or claim 6, which comprises about 0.05 ml to about 7.5ml of an insect repellent.

8. A preparation as claimed in any one of claims 2 to 7, which comprises citric acid as binding agent.

9. A preparation as claimed in claim 8 which comprises about 0.1 to about 1 g of citric acid.

10. A preparation for a sacrificial anti-graffiti surface coating as claimed in claim 1 , wherein a saccharide is dissolved in linseed oil or turpentine and the solution used to soften beeswax, a softened film of beeswax being applicable to a surface to be protected.

11. A method of making a sacrificial anti-graffiti surface coating as claimed in claims 2 to 9, the step comprising mixing a mixture as defined above with the required amount of water.

12. A method as claimed in claim 11 , wherein the temperature of the water is about ambient to 50^°C or above.

13. A kit comprising a preparation for a sacrificial anti-graffiti surface coating as claimed in any one of claims 1 to 12, the ingredients being contained in the kit together or separately, and the kit being arranged so that the ingredients may be mixed with sufficient water or organic solvent to prepare a sacrificial anti-graffiti coating.