AU2006201466A1

AU2006201466A1 - Marine Growth Inhibitor

Info

Publication number: AU2006201466A1
Application number: AU2006201466A
Authority: AU
Inventors: Robert Peter Morgan
Original assignee: Blue Lagoon Pearls Pty Ltd
Current assignee: Blue Lagoon Pearls Pty Ltd
Priority date: 2005-04-01
Filing date: 2006-03-31
Publication date: 2006-10-19

Description

-2- "Marine Growth Inhibitor" Field of the Invention The present invention relates to a marine growth inhibitor and a method for inhibiting the attachment of marine fouling organisms on molluscs and equipment associated with mollusc aquaculture.

Background Art At certain times of the year, depending on the location, molluscs produce spawn that on fertilisation, are known as spats. In nature, spats may float freely for about one month and then either fix themselves to, for example, a coral or die, buried in the sand. On mollusc farms and in particular, oyster farms, spats may be collected by submerging artificial collectors (such as shade cloth) into lagoons. After a period of time which may be up to a few months, the young oysters may be transferred to panels on 'long lines' for further growth.

Nucleated pearl oysters may be moved into 'post-operative' care, where they hang in relatively crowded baskets, located in lagoons for a week or two near the pearl laboratory. Molluscs that survive and accept the grafts get moved into panels in open waters and are allowed to spread out, leaving enough room between animals so that they can grow and feed.

During all growth phases, it is necessary for the oyster shells and associated equipment such as holding nets, panels, long lines and buoys to be regularly cleaned. Cleaning removes marine fouling barnacles) on the shells and associated equipment thereby reducing weight on the lines and minimising the risk of disease of the mollusc. Cleaning is performed either manually with scrapers or, more commonly, with high-pressure water cleaning machines.

Regardless of the method employed, cleaning is a time-consuming process that adds significantly to the cost of operating a mollusc farm. It is an object of this invention to provide an inhibitor that increases the time period between cleaning by decreasing the amount of fouling on the shell and associated equipment.

-3- Known cleaning processes, for example, the use of high-pressure water, can remove coatings applied to the surfaces of molluscs resulting in the presentation of fresh shell to fouling organisms. It is an object of this invention to provide a inhibitor adapted to better withstand known cleaning forces than inhibitors of the prior art.

The preceding discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia as at the priority date of the application.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Disclosure of the Invention In accordance with the present invention, there is provided a mollusc coating marine growth inhibitor, adapted to adhere to a mollusc shell and inhibit the adherence of marine fouling organisms thereto, wherein the inhibitor comprises wax and is solid at ambient temperature such that it provides a physical barrier between the mollusc shell and the marine fouling organisms and a binder adapted to increase the hardness of the inhibitor and to increase the adhesion of the inhibitor to the mollusc shell and wherein the inhibitor is sufficiently frangible at ambient temperature to allow a mollusc to breathe and feed..

In the context of this specification the term solid is intended to define a state with a persistence of form that may also be deformable.

The inhibitor of the present invention confers the advantage of providing increased resistance to marine fouling organisms than a composition in a liquid state.

-4- In the context of this specification, marine fouling organisms may include sponges, barnacles, squirt balls, limpets, fireweed, sea worms and coral.

The inhibitor of the present invention confers the advantage of providing increased resistance to dislodgement using cleaning techniques known in the art than a inhibitor in a liquid state. The inhibitor confers the further advantage of providing increased resistance to known cleaning methods than a inhibitor in a solid state without a binder.

Without being limited by theory, it is believed that the textural characteristics of the surface of the inhibitor exposed to a marine environment are related to the inhibitory properties of the inhibitor. It is believed that the smoother the exposed surface of the inhibitor, the more difficult it is for marine fouling organisms to adhere to the exposed surface of the inhibitor.

The inhibitor of the present invention confers the advantage of decreasing the frequency of cleaning of mollusc shells by inhibiting the adherence of marine fouling organisms.

The inhibitor of the present invention is particularly suited for the inhibition of marine growth on bivalves and univalves.

Preferably, the binder is provided in the form of a solvent free binder.

Preferably, the binder comprises a thermoplastic polymer. In preferred forms of the invention, the thermoplastic polymer may be selected from the group consisting of: ethylene vinyl acetate copolymers, styrene-isoprene-styrene copolymers; styrene-butadiene-styrene copolymers, ethylene ethyl acrylate copolymers and polyurethanes. More preferably, the thermoplastic polymer is a ethylene vinyl acetate copolymer.

Preferably, the binder comprises additives to enhance adhesive properties. Said additives may include diluents, waxes, plasticisers, tackifiers and stabilisers.

In a very highly specific form of the invention, the binder is provided in the form of hot melt and in particular, BOSTIK 6136 HOT MELT by Bostik Australia Pty Ltd.

Preferably, the inhibitor comprises up to about 30 by weight binder. More preferably, the inhibitor comprises between about 5 to 15 by weight binder.

Preferably, the inhibitor is sufficiently adhesive to substantially resist dislodgement from a mollusc shell under high-pressure water cleaning conditions up to 150 p.s.i. More preferably, the inhibitor will substantially resist dislodgement from the mollusc shell under high-pressure water cleaning conditions up to 250 p.s.i. More preferably still, the inhibitor will substantially resist dislodgement from the mollusc shell under high-pressure water cleaning conditions up to 300 p.s.i. More preferably still, the inhibitor will substantially resist dislodgement from the mollusc shell under high-pressure water cleaning conditions up to 400 p.s.i. In a particular form of the invention, the inhibitor will substantially resist dislodgement from the mollusc shell under high-pressure water cleaning conditions up to 600 p.s.i.

Preferably, the inhibitor melts at a temperature such that a mollusc dipped into a liquefied composition of the inhibitor remains viable.

Preferably, the inhibitor melts between about 40 to 160 More preferably, the inhibitor melts between about 50 to 120 Even more preferably, the inhibitor melts between about 60 to 95 °C.

In one form of the invention, the wax comprises long chain hydrocarbons and/or esters of long chain alcohols and long chain fatty acids.

In a particular form of the invention, the inhibitor comprises petroleum wax. In the context of this specification, the term petroleum wax encompasses both paraffin wax and microcrystalline wax, wherein paraffin wax is a substantially fully saturated and substantially straight chain hydrocarbon and microcrystalline wax is a substantially fully saturated hydrocarbon with a significant proportion of branched and cyclic structures.

Where the inhibitor comprises paraffin wax, the carbon number of the paraffin wax is preferably greater than about 25. More preferably, the carbon number is between about 25 and -6- Where the inhibitor comprises microcrystalline wax, the carbon number of the microcrystalline wax is preferably greater than about 25. More preferably, the carbon number is between about 25 and In one form of the invention, the inhibitor comprises a mixture of paraffin wax and microcrystalline wax. It should be appreciated that the optimum ratio of paraffin wax and microcrystalline wax will vary according to the application of the inhibitor. Differences in mollusc species, wax types and water conditions may affect the final constitution of the inhibitor. Bivalves breathe and feed by opening their shells and pumping water over their gills. If an animal is prevented from opening its shells, it will eventually die. The strength of the adductor muscle on different species of bivalves is known to vary significantly, and an inhibitor that may be sufficiently frangible for one species may not be so for another. At higher water temperatures, higher proportions of microcrystalline wax should be used to reduce softening of the inhibitor.

Without being limited by theory, it is believed that as the proportion of paraffin wax to microcrystalline wax increases, the inhibitor becomes more frangible, but less adhesive to the mollusc shell.

Preferably, the inhibitor comprises between about 0 to 95 by weight paraffin wax and between about 5 to 100 by weight microcrystalline wax. More preferably, the inhibitor comprises between about 0 to 70 by weight paraffin wax and between about 30 to 100 by weight microcrystalline wax. More preferably still, the inhibitor comprises between about 20 to 60 by weight paraffin wax and between about 40 to 70 by weight microcrystalline wax.

Without being limited by theory, it is believed that as the water temperature in which the inhibitor is to be used rises, the inhibitor softens, said softening facilitating the ingress of marine fouling organisms through the inhibitor. The hardness of the inhibitor may be increased by increasing the proportion of those components in the inhibitor with higher melting points, for example, the microcrystalline wax or the binder/adhesive.

-7- Where the water temperature in which the inhibitor is to be used is less than about 30 C, the inhibitor preferably comprises between about 40 to 50 by weight paraffin wax and between about 40 to 50 by weight microcrystalline wax. Where the water temperature is greater than about 30 0C, the inhibitor preferably comprises between about 20 to 30 by weight paraffin wax and between about 60 to 70 by weight microcrystalline wax.

Where the inhibitor comprises a wax, the inhibitor may further comprise a plasticiser adapted to decrease the brittleness of the inhibitor at ambient temperature.

Preferably, the plasticiser is provided in the form of an oil. In one form of the invention, the plasticiser is provided in the form of a paraffin oil. In the context of this specification, the term 'paraffin oil' is intended to encompass a liquid hydrocarbon or mixture of liquid hydrocarbons obtained from petroleum. In a specific form of the invention, the plasticiser is provided in the form of an engine oil, and in particular, a diesel engine oil.

Without being limited by theory, it is believed that the plasticiser increases the smoothness of the inhibitor thereby increasing the inhibiting properties of the inhibitor.

The inhibitor preferably comprises between about 0.1 to 20 by weight plasticiser. More preferably, the inhibitor comprises between about 1 to 10 by weight plasticiser. More preferably still, the inhibitor comprises about 5 by weight plasticiser. It will be appreciated that the final amount of plasticiser used in the inhibitor will depend on the final use of the inhibitor and the nature of the plasticiser used.

Without being limited by theory, it is believed that as the proportion of plasticiser increases beyond about 20 the inhibitor becomes less adhesive to the mollusc shell as well as becoming more difficult to work with.

In one specific embodiment of the invention, the inhibitor comprises microcrystalline wax (67 paraffin wax (23 binder (5 W/w) and plasticiser (5 V/w).

-8- In a second specific embodiment of the invention, the inhibitor comprises microcrystalline wax (53 paraffin wax (26 binder (16 W/w) and plasticiser (5 V/w).

In a third specific embodiment of the invention, the inhibitor comprises microcrystalline wax (45 paraffin wax (45 binder (5 W/w) and plasticiser (5 The inhibitor may further comprise a hardener. In one form of the invention, the hardener may be provided in the form of a highly branched hydrocarbon polymer.

In a highly specific form of the invention, the hardener is a hydrocarbon polymer of alpha olefins.

Hydrocarbon polymers prepared from alpha olefins, polymerised or copolymerised in the presence of free radicals at low pressures are highly branched, have increased molecular weight, higher viscosities and greater hardness but lower melting and congealing points than the original alpha olefins from which they are derived (RCH=CH 2 Within the context of the specification, the term alpha olefins is to be understood to include alpha olefins of the vinylidene structure (R 2

C=CH

2 In a very highly specific form of the invention, the hydrocarbon polymer is provided in the form of the material sold under the trade mark VYBAR® and in particular, VYBAR@103 by Baker Petrolite.

The addition of the hardener provides the advantage of increasing the hardness of the inhibitor without increasing its melting point.

Without being limited by theory, it is believed that the hardener decreases the size of crystals of the wax which are formed on cooling thereby making the inhibitor harder and more water resistant. Where the inhibitor comprises plasticiser, it is further believed that the hardener increases the capacity of the inhibitor to retain the plasticiser.

Where the inhibitor comprises hardener, the inhibitor preferably comprises between about 0.1 to 5 by weight hardener. More preferably, the inhibitor -9comprises between about 0.1 to 3 by weight hardener. More preferably still, the inhibitor comprises between about 0.3 to 1 by weight hardener. More preferably still, the inhibitor comprises about 0.45 by weight hardener.

The inhibitor may comprise one or more colouring agents which can aid identification of molluscs. For example, molluscs may be colour coded according to their ages. The colouring agent may also assist in the protection of molluscs by predatory animals, either by camouflage or deterrence.

Where the inhibitor comprises a colouring agent, the colouring agent may be provided in the form of a vegetable dye or a pigment, for example those used in the tinting of paints or candles. Preferably, the colouring agent is substantially UV stable.

It should be appreciated that the amount of colouring agent will be very small and should not affect the mollusc or its properties. In one form of the invention, the inhibitor comprises between about 0.002 and about 0.01 by weight of colouring agent. It will be appreciated that the amount of colouring agent used will depend on the colour of the colouring agent, lighter colours, requiring more colouring agent.

In accordance with the present invention, there is provided a method for treating molluscs to inhibit the growth of marine fouling organisms thereon, the method comprising the steps of: applying a mollusc coating marine growth inhibitor in a liquid state comprising a binder, to at least a portion of a mollusc shell; and causing the inhibitor to solidify, such that the solid marine growth inhibitor provides a physical barrier between the mollusc shell and the marine fouling organisms.

In one form of the invention, the step of causing the inhibitor to solidify encompasses allowing the inhibitor to cool.

It should be appreciated that the step of causing the inhibitor to solidify could be achieved by evaporation or chemical reaction.

The method of the present invention confers the advantage of being able to kill marine fouling organisms that may be present on the mollusc shell prior to the step of applying the inhibitor to at least a portion of the mollusc shell, for example, by suffocation.

The step of applying the marine growth inhibitor in a liquid state to at least a portion of a mollusc shell may be performed by: applying the marine growth inhibitor to the mollusc shell by dipping, spraying or painting.

The inhibitor is preferably maintained at a temperature of greater than about 0C during application of the inhibitor to the mollusc shell. More preferably, the inhibitor is maintained at a temperature of between about 60 and 100 0C. Most preferably, the inhibitor is maintained at a temperature of between about 80 and 95 °C.

It should be appreciated that the thickness of the inhibitor and the frangibility of the inhibitor will influence the ability of the mollusc to breathe and feed.

Preferably, the inhibitor is applied to a thickness of between about 0.5 mm to mm. More preferably, the thickness is between about 0.5 mm and 2.0 mm.

More preferably, the thickness is about 1.0 mm.

The method may comprise the additional step of: drying the mollusc shell prior to applying the marine growth inhibitor in a liquid state to at least a portion of the mollusc shell.

In another form of the invention, the method may comprise the additional step of: applying a second marine growth inhibitor in a liquid state to at least a portion of the mollusc shell; and causing the inhibitor to solidify.

-11 In a specific form of the invention, the first and second marine growth inhibitors are the same.

In accordance with the present invention, there is provided a mollusc coating marine growth inhibitor, adapted to adhere to mollusc farming equipment and inhibit the adherence of marine fouling organisms thereto, wherein the inhibitor comprises wax and is solid at ambient temperature such that it provides a physical barrier between the mollusc farming equipment and the marine fouling organisms and comprises a binder adapted to increase the hardness of the inhibitor and to increase the adhesion of the inhibitor to the mollusc farming equipment.

In the context of this specification, mollusc farming equipment may include panels, lines and buoys, nets, mesh bags, onion bags, trays, cages, floats, pots sea-cages, cables and markers, both floating and fixed, for example, pylons as well as underwater probes, including those for measuring water temperatures and pH and for detecting underwater objects both fixed and moving including animals and machines, including submarines.

The inhibitor of the present invention confers the advantage of providing increased resistance to dislodgement using cleaning techniques known in the art than a inhibitor in a liquid state. The inhibitor further confers the advantage of providing increased resistance to known cleaning methods than a inhibitor in a solid state without an binder/adhesive.

The inhibitor of the present invention confers the advantage of decreasing the frequency of cleaning of mollusc farming equipment by inhibiting the adherence of marine fouling organisms.

Preferably, the binder is provided in the form of a solvent free binder.

Preferably, the binder comprises a thermoplastic polymer. In preferred forms of the invention, the thermoplastic polymer may be selected from the group consisting of: ethylene vinyl acetate copolymers, styrene-isoprene-styrene copolymers; styrene-butadiene-styrene copolymers, ethylene ethyl acrylate -12copolymers and polyurethanes. Most preferably, the thermoplastic polymer is a ethylene vinyl acetate copolymers.

Preferably, the inhibitor comprises up to about 50 by weight binder. More preferably, the inhibitor comprises between 5 to 30% by weight binder. More preferably, the inhibitor comprises between about 5 to 15 by weight binder.

Preferably, the inhibitor melts between about 20 to 200 More preferably, the inhibitor melts between about 40 to 150 Even more preferably, the inhibitor melts between about 50 to 100 °C.

Preferably, the inhibitor comprises a wax. In one form of the invention, the wax is comprises long chain hydrocarbons and/or esters of long chain alcohols and long chain fatty acids.

In a particular form of the invention, the inhibitor comprises petroleum wax. In the context of this specification, the term petroleum wax encompasses both paraffin wax and microcrystalline wax, wherein paraffin wax is a substantially -13fully saturated and substantially straight chain hydrocarbon and microcrystalline wax is a substantially fully saturated hydrocarbon with a significant proportion of branched and cyclic structures.

Where the inhibitor comprises paraffin wax, the carbon number of the wax is preferably greater than about 25. More preferably, the carbon number of the paraffin wax is between about 25 and Where the inhibitor comprises microcrystalline wax, the carbon number of the microcrystalline wax is preferably greater than about 25. More preferably, the carbon number of the microcrystalline wax is between about 25 and In one form of the invention, the inhibitor comprises a mixture of paraffin wax and microcrystalline wax. It should be appreciated that the optimum ratio of paraffin wax and microcrystalline wax will vary according to the application of the inhibitor. Differences in farming equipment properties, wax types and water conditions may affect the final constitution of the inhibitor. For example, at higher water temperatures, higher proportions of microcrystalline wax should be used to reduce softening of the inhibitor.

In one form of the invention, the inhibitor comprises a mixture of paraffin wax and microcrystalline wax. Where the inhibitor comprises a mixture of paraffin wax and microcrystalline wax, preferably the paraffin wax comprises between about 10 to 50 by weight of the inhibitor and the microcrystalline wax comprises between about 50 to 90 by weight of the inhibitor. More preferably, the paraffin wax comprises between about 20 to 50 by weight of the inhibitor and the microcrystalline wax comprises between about 50 to 80 by weight of the inhibitor. More preferably still, the paraffin wax comprises between about 20 to 40 by weight of the inhibitor and the microcrystalline wax comprises between about 60 to 70 by weight of the inhibitor. Most preferably, the paraffin wax comprises about 30% by weight of the inhibitor and the microcrystalline wax comprises about 70 by weight of the inhibitor.

-14- Where the inhibitor comprises wax, the inhibitor may further comprise a plasticiser adapted to decrease the brittleness of the inhibitor at ambient temperature.

The inhibitor may further comprise a hardener. In one form of the invention, the hardener may be provided in the form of a highly branched hydrocarbon polymer.

In a very highly specific form of the invention, the hardener is provided in the form of the material sold under the trade mark VYBAR® and in particular, VYBAR®103 by Baker Petrolite.

Where the inhibitor comprises hardener, the inhibitor preferably comprises between about 0.1 to 5 by weight hardener. More preferably, the inhibitor comprises between about 0.1 to 3 by weight hardener. More preferably still, the inhibitor comprises between about 0.3 to 1 by weight hardener. More preferably still, the inhibitor comprises about 0.45 by weight hardener.

The inhibitor may comprise one or more colouring agents. The colouring agent may be provided in the form of a vegetable dye or a pigment, for example those used in the tinting of paints or candles. Preferably, the colouring agent is substantially UV stable.

In accordance with the present invention, there is provided a method for treating mollusc farming equipment to inhibit the growth of marine fouling organisms thereon, the method comprising the steps of: applying a mollusc coating marine growth inhibitor in a liquid state, comprising a binder, to at least a portion of the mollusc farming equipment; and causing the inhibitor to solidify such that the marine growth inhibitor provides a physical barrier between the mollusc farming equipment and the marine fouling organisms.

The step of applying the marine growth inhibitor in a liquid state to at least a portion of a mollusc shell may be performed by: applying the marine growth inhibitor to the mollusc farming equipment by dipping, spraying or painting.

In one form of the invention, the method may comprise the additional step of: removing excess liquid inhibitor from the equipment prior to the step of causing the inhibitor to solidify.

Most preferably, the thickness is between about 1.0 mm and 1.5 mm.

In accordance with the present invention, there is provided a method for the preparation of a marine growth inhibitor, the method comprising the steps of: -16blending liquefied microcrystalline wax and liquefied paraffin wax to provide a first liquid in a first container; adding a portion of the first liquid to a melted portion of a binder in a second container to provide a second liquid; adding the second liquid to the first container; and allowing the contents of the first container to cool and solidify.

In one form of the invention, the method comprises the further steps of: adding oil and pigment to the first container after the contents of the second container are added to the first container.

Best Mode(s) for Carrying Out the Invention The method and inhibitor of the present invention will now be described, by way of example only, with reference to one embodiment of the inhibitor and three embodiments of the method of application of the inhibitor.

By way of example, the method of the present invention is described in the context of an marine growth inhibitor and a method for treating pearl oysters and pearl oyster farming equipment to inhibit the growth of marine fouling organisms thereon, although such should not be seen as limiting the generality of the foregoing description.

Inhibitor Preparation To prepare a large batch of inhibitor, (over 50 kg), microcrystalline wax with a melting point of 80 0C (45 W/w) was added to a first container at room temperature followed by paraffin wax with a melting point of 55 0C (45 W/w).

The container was heated with stirring and both waxes melted. A binder in the form of BOSTIK 6136 HOT MELT (5 was added to a second container which was heated with stirring until the hot melt became liquid. Approximately of the liquefied wax mixture of the first container was added to the second container with stirring. The wax and hot melt mixture of the second container ~1 ~1 -17was then returned to the first container with stirring. Investigations show that if the liquefied hot melt is not diluted with a portion of the wax mixture, it will not mix well with the waxes. Heating was removed from the first container and engine oil (5 was added to the mixture. Finally, pigment (0.002 was slowly added to the mixture with stirring. The mixture was poured into moulds and allowed to cool.

To prepare a smaller batch of inhibitor, (less than 50 kg), binder in the form of BOSTIK 6136 HOT MELT (5 was added to a container and heated until it liquefied. Microcrystalline wax with a melting point of 80 0C (45 W/w) was added to the container followed by paraffin wax with a melting point of 55 0C W/w) and the waxes liquefied and stirred. The heating was removed and engine oil (5 V/w) and pigment (0.002 added to the mixture with stirring. The mixture was poured into moulds and allowed to cool.

Inhibitor Application To apply the inhibitor to an oyster shell in accordance with a first embodiment, a sample of inhibitor comprising microcrystalline 80 (45 paraffin BOSTIK 6136 HOT MELT (5 engine oil (5 V/w) and pigment (0.002 was heated in a container to between 80 0C and 95 0C at which point it was a liquid and approximately half of a shell was dipped into the liquid for about 2 s and allowed to cool and harden. The dipping process was repeated on the remaining half of the shell. The shell was then attached to a panel in the known manner.

To apply the inhibitor to an oyster shell in accordance with a second embodiment, a sample of inhibitor comprising microcrystalline 80 (45 W/w), paraffin 55 (45 BOSTIK 6136 HOT MELT (5 engine oil (5 V/w) and pigment (0.002 was heated in a container to between 80 0C and 95 0C at which point it was a liquid. A shell, held by a pair of point nosed pliers at the top of the shell was immersed into the liquid for about 2 s and allowed to cool and harden. The shell was then attached to a panel in the known manner.

-18- To apply the inhibitor to panel for use with oysters, a sample of inhibitor comprising microcrystalline 80 (63 paraffin 55 (22 BOSTIK 6136 HOT MELT (10 engine oil (5 V/w) was heated in a container to between °C and 95 °C at which point it was a liquid. A panel was immersed into the liquid for about 1 s to 5 s and allowed to cool and harden.

To apply the inhibitor to a number oyster shells on a panel, a sample of inhibitor comprising microcrystalline 80 (45 paraffin 55 (45 BOSTIK 6136 HOT MELT (5 engine oil (5 V/w) and pigment (0.002 was heated in a container to between 80 °C and 95 °C at which point it was a liquid. The panel and shells were immersed into the liquid for about 2 s and allowed to cool and harden. The panel was then attached to a long line in the known manner.

Prior to covering shells with inhibitor, the shells should be closed. Closing of the shells may be achieved by gentle tapping of a shell before immersion.

To apply the inhibitor to pylons, sea-cages, cables and other larger pieces of equipment associated with pearl farming, a sample of inhibitor comprising microcrystalline 80 (63 paraffin 55 (22 BOSTIK 6136 HOT MELT engine oil (5 V/w) was heated in a container to between 80 °C and °C at which point it was a liquid. The liquid inhibitor was applied by spraying the inhibitor onto the surface to be coated at 95 °C with a hot spray gun.

Inhibitor adherence trials In order to assess the ability of the inhibitor to remain adhered to the mollusc and panel during cleaning, a number of oysters on a panel treated with the inhibitor described above were washed with high pressure water in a conventional shell washer. The results (Table 1) show that the inhibitor is capable of withstanding repeated washings at 400 psi without breaking or being removed from the shell.

The adherence trials were conducted approximately 10 minutes after application of the inhibitor.

-19- Wash Water Number pressure I psi Observations 1 300 No inhibitor removed from shell or panel 2 300 No inhibitor removed from shell or panel 3 400 No inhibitor removed from shell or panel 4 400 No inhibitor removed from shell or panel 400 No inhibitor removed from shell or panel 6 400 No inhibitor removed from shell or panel 7 400 No inhibitor removed from shell or panel 8 400 No inh ibitor removed from shell; minor cracking around lips of 4b rshell 9 400 No inhibitor removed from shell; minor cracking around lips of shell 400 No inhibitor removed from shell; minor cracking around lips of 40 No ii shell and on parts of panel Table 1. Inhibitor adherence trials.

Inhibitor adherence trials after exposure In order to assess whether storage in water affects the adherence of the inhibitor, a number of oysters coated with the inhibitor as described above were placed on an untreated panel and stored in sea water in the normal manner for 8 weeks. At the end of the trial period, no marine growth was observed on the shells. The ability of the inhibitor to remain adhered to the mollusc during cleaning processes was tested as described above (Table 2).

Wash Water Ia Number pressure psi Observations 1 200 No inhibitor removed from shell 2 250 No inhibitor removed from shell 3 300 No inhibitor removed from shell 4 300 No inhibitor removed from shell 400 No inhibitor removed from shell 6 400 No inhibitor removed from shell 7 400 No inhibitor removed from shell 8 400 No inhibitor removed from shell 9 400 No inhibitor removed from shell 400 No inhibitor removed from shell; minor cracking around lips of shell 11 I 400 No inhibitor removed from shell; minor cracking around lips of shell 12 400 No inhibitor removed from shell; minor cracking around lips of shell 13 600 Approximately 5 inhibitor removed from shell Table 2. Inhibitor adherence trials.

The results show that the inhibitor is capable of withstanding repeated washings at 400 psi without breaking or being removed from the shell. Even washing at 600 psi caused only minimal removal of the inhibitor from the shell.

Mode of action trials Panels and shells were treated with the inhibitor described above to assess whether the inhibitor was acting as an antifoulant by killing settling organisms or an inhibitor by stopping settling organisms from resting on shells and panels.

Three sets of panels with oysters attached to them in the usual manner (Numbers 1, 2 and 3) were dipped into a container containing liquefied inhibitor.

Three further sets of panels with oysters attached to them in the usual manner (Numbers 4, 5 and 6) were sprayed with liquefied inhibitor with a high temperature spray gun.

Number Application Observations 1 II Dip II No marine growth present 2 Dip II No marine growth present 3 II Dip II No marine growth present 4 I[ Spray II Covered with 3 mm of brown weed I[ Spray II Covered with 3 mm of brown weed 6 I[ Spray II Covered with 3mm of brown weed Table 3. Mode of action trials.

Inhibitor hardness trials A number of inhibitors with varying compositions were prepared and analysed to assess the hardness of the inhibitors at various water temperatures. The compositions of the five inhibitors are shown in Table 4.

Test samples 1 and 2 were prepared as blocks and left in direct sunlight for minutes at 48 Test sample 1 ran and pooled and Test sample 2 retained its original shape but was slightly soft to touch. The results show that the use of increasing amounts of binder increases the ability of the inhibitor to retain its shape at high temperatures.

Test samples 3, 4 and 5 were prepared as 8 kg blocks and left in direct sunlight for 90 minutes at 36 0C. A 70 kg weight on a pole was placed on top of each -21block for 10 s and the distance of ingress of the pole into each block measured.

The results show that the use of increasing amounts of microcrystalline wax increases the hardness of the inhibitor.

Sample HOT 1 Observation Number microcrystalline paraffin MELT engine Numbr 80(w/w) 55 (ww) (ww) oil(vw) pigment 1 44.5 44.5 6 5 0.02 Sloppy 2 32.5 32.5 30 5 0.02 Soft 3 44.5 44.6 6 5 0.02 16mm 4 60 29 6 5 0.02 67 I 22 6 5 0.02 13 mm Table 4. Inhibitor hardness trials.

While advantageous and preferred embodiments of the present invention have been selected as illustrations of the invention, it should be understood by those skilled in the art that changes and adaptations can be made therein without departing from the scope of the invention.

Claims

1. A mollusc coating marine growth inhibitor, adapted to adhere to a mollusc shell and inhibit the adherence of marine fouling organisms thereto, wherein the inhibitor comprises wax and is solid at ambient temperature such that it provides a physical barrier between the mollusc shell and the marine fouling organisms and a binder adapted to increase the hardness of the inhibitor and to increase the adhesion of the inhibitor to the mollusc shell and wherein the inhibitor is sufficiently frangible at ambient temperature to allow a mollusc to breathe and feed.

2. A mollusc coating marine growth inhibitor according to claim 1, wherein the binder is a solvent free binder.

3. A mollusc coating marine growth inhibitor according to claim 1 or 2, wherein the binder comprises a thermoplastic polymer.

4. A mollusc coating marine growth inhibitor according to claim 3, wherein the thermoplastic polymer is selected from the group consisting of: ethylene vinyl acetate copolymers, styrene-isoprene-styrene copolymers; styrene-butadiene-styrene copolymers, ethylene ethyl acrylate copolymers and polyurethanes.

5. A mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the binder comprises additives such as diluents, waxes, plasticisers, tackifiers and stabilisers, adapted to enhance adhesive properties.

6. A mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the binder is a hot melt and in particular, BOSTIK 6136 HOT MELT by Bostik Australia Pty Ltd.

7. A mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the inhibitor comprises up to about 30 by weight binder. i -23-

8. A mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the inhibitor comprises between about 5 to by weight binder.

9. A mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the inhibitor is sufficiently adhesive to substantially resist dislodgement from a mollusc shell under high-pressure water cleaning conditions up to 600 p.s.i. mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the inhibitor melts at a temperature such that a mollusc dipped into a liquefied composition of the inhibitor remains viable.

11.A mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the inhibitor melts between about 40 to 160 °C.

12.A mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the inhibitor melts between about 50 to 120 0C.

13.A mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the inhibitor melts between about 60 to 95 °C.

14.A mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the wax comprises long chain hydrocarbons and/or esters of long chain alcohols and long chain fatty acids.

15.A mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the inhibitor comprises petroleum wax.

16.A mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the inhibitor comprises paraffin wax.

17.A mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the inhibitor comprises microcrystalline wax. -24-

18.A mollusc coating marine growth inhibitor according to claim 17, wherein the inhibitor comprises between about 0 to 95 by weight paraffin wax and between about 5 to 100 by weight microcrystalline wax.

19.A mollusc coating marine growth inhibitor according to claim 17, wherein the inhibitor comprises between about 0 to 70 by weight paraffin wax and between about 30 to 100 by weight microcrystalline wax. mollusc coating marine growth inhibitor according to claim 17, wherein the inhibitor comprises between about 20 to 60 by weight paraffin wax and between about 40 to 70 by weight microcrystalline wax.

21.A mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the inhibitor further comprises a plasticiser adapted to decrease the brittleness of the inhibitor at ambient temperature.

22.A mollusc coating marine growth inhibitor according to claim 21, wherein the plasticiser is provided in the form of an oil.

23.A mollusc coating marine growth inhibitor according to claim 22, wherein plasticiser is provided in the form of a paraffin oil.

24.A mollusc coating marine growth inhibitor according to claim 23, wherein plasticiser is provided in the form of an engine oil.

25.A mollusc coating marine growth inhibitor according to any one of claims 21 to 24, wherein the inhibitor comprises between about 0.1 to 20 by weight plasticiser.

26.A mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the inhibitor further comprises a hardener.

27.A mollusc coating marine growth inhibitor according to claim 26, wherein the hardener is provided in the form of a highly branched hydrocarbon polymer.

28.A mollusc coating marine growth inhibitor according to claim 27, wherein the hardener is a hydrocarbon polymer of alpha olefins.

29.A mollusc coating marine growth inhibitor according to any one of the preceding claims, wherein the inhibitor comprises one or more colouring agents. method for treating molluscs to inhibit the growth of marine fouling organisms thereon, the method comprising the steps of: applying a mollusc coating marine growth inhibitor in a liquid state comprising wax and a binder, to at least a portion of a mollusc shell; and causing the inhibitor to solidify, such that the solid mollusc coating marine growth inhibitor provides a physical barrier between the mollusc shell and the marine fouling organisms.

31. A method for treating molluscs according to claim 30, wherein the step of applying the mollusc coating marine growth inhibitor in a liquid state to at least a portion of a mollusc shell comprises: applying the mollusc coating marine growth inhibitor to the mollusc shell by dipping, spraying or painting.

32.A method for treating molluscs according to claim 30 or 31, wherein the inhibitor is maintained at a temperature of greater than about 45 °C during application of the inhibitor to the mollusc shell.

33.A method for treating molluscs according to claim 30 or 31, wherein the inhibitor is maintained at a temperature of between about 60 and 100 °C during application of the inhibitor to the mollusc shell. -26-

34.A method for treating molluscs according to claim 30 or 31, wherein the inhibitor is maintained at a temperature of between about 80 and 95 °C during application of the inhibitor to the mollusc shell. method for treating molluscs according to any one of claims 30 to 34, wherein the inhibitor is applied to a thickness of between about 0.5 mm to mm.

36.A method for treating molluscs according to any one of claims 30 to wherein the method comprises the additional step of: drying the mollusc shell prior to applying the marine growth inhibitor in a liquid state to at least a portion of the mollusc shell.

37.A marine growth inhibitor, adapted to adhere to mollusc farming equipment and inhibit the adherence of marine fouling organisms thereto, wherein the inhibitor comprises wax and is solid at ambient temperature such that it provides a physical barrier between the mollusc farming equipment and the marine fouling organisms and comprises a binder adapted to increase the hardness of the inhibitor and to increase the adhesion of the inhibitor to the mollusc farming equipment.

38.A marine growth inhibitor according to claim 37, wherein the binder is a solvent free binder.

39.A marine growth inhibitor according to claim 37 or 38, wherein, the binder is a thermoplastic polymer. marine growth inhibitor according to claim 37, wherein the thermoplastic polymer is selected from the group consisting of: ethylene vinyl acetate copolymers, styrene-isoprene-styrene copolymers; styrene-butadiene- styrene copolymers, ethylene ethyl acrylate copolymers and polyurethanes. -27-

41.A marine growth inhibitor according to any one of claims 37 to 40, wherein the binder comprises additives such as diluents, waxes, plasticisers, tackifiers and stabilisers, adapted to enhance adhesive properties.

42.A marine growth inhibitor according to any one of claims 37 to 41, wherein the binder is a hot melt and in particular, BOSTIK 6136 HOT MELT by Bostik Australia Pty Ltd.

43.A marine growth inhibitor according to any one of claims 37 to 42, wherein the inhibitor comprises up to about 50 by weight binder.

44.A marine growth inhibitor according to any one of claims 37 to 42, wherein the inhibitor comprises between 5 to 30% by weight binder. marine growth inhibitor according to any one of claims 37 to 42, wherein the inhibitor comprises between about 5 to 15 by weight binder.

46.A marine growth inhibitor according to any one of claims 37 to 45, wherein the inhibitor is sufficiently adhesive to substantially resist dislodgement from a mollusc shell under high-pressure water cleaning conditions up to 600 p.s.i.

47.A marine growth inhibitor according to any one of claims 37 to 46, wherein the inhibitor comprises petroleum wax.

48.A marine growth inhibitor according to claim 47, wherein the inhibitor comprises paraffin wax.

49.A marine growth inhibitor according to claim 47, wherein the inhibitor comprises microcrystalline wax. marine growth inhibitor according to claim 49, wherein the inhibitor comprises between about 10 to 50 by weight paraffin wax and between about 50 to 90 by weight microcrystalline wax. ID-28- \O o 51.A marine growth inhibitor according to any one of claims 37 to 50, wherein the inhibitor further comprises a plasticiser adapted to decrease the Sbrittleness of the inhibitor at ambient temperature. C' 52.A marine growth inhibitor according to claim 51, wherein the plasticiser is provided in the form of an oil. \O \O

53.A marine growth inhibitor according to claim 52, wherein the plasticiser is 0 provided in the form of a paraffin oil. \O S54.A marine growth inhibitor according to claim 53, wherein the plasticiser is (1 provided in the form of an engine oil.

55.A marine growth inhibitor according to any one of claims 51 to 54, wherein the inhibitor comprises between about 0.1 to 20 by weight plasticiser.

56.A marine growth inhibitor according to any one of claims 37 to 55, wherein the inhibitor further comprises a hardener.

57.A marine growth inhibitor according to claim 56, wherein the hardener is provided in the form of a highly branched hydrocarbon polymer.

58.A marine growth inhibitor according to claim 57, wherein the hardener is a hydrocarbon polymer of alpha olefins.

59.A marine growth inhibitor according to any one of claims 37 to 58, wherein the inhibitor comprises one or more colouring agents.

60.A method for treating mollusc farming equipment to inhibit the growth of marine fouling organisms thereon, the method comprising the steps of: applying a marine growth inhibitor in a liquid state, comprising wax and a binder, to at least a portion of the mollusc farming equipment; and causing the inhibitor to solidify, -29- such that the solid marine growth inhibitor provides a physical barrier between the mollusc farming equipment and the marine fouling organisms.

61.A method for treating mollusc farming equipment according to claim wherein the step of applying the marine growth inhibitor in a liquid state to at least a portion of the mollusc farming equipment comprises: applying the marine growth inhibitor to the mollusc farming equipment by dipping, spraying or painting.

62.A method for the preparation of a marine growth inhibitor, the method comprising the steps of: blending liquefied microcrystalline wax and liquefied paraffin wax in a first container to provide a first liquid; adding a portion of the first liquid to a melted portion of a binder in a second container to provide a second liquid; adding the second liquid to the first container; and allowing the contents of the first container to cool and solidify.

63.A method in accordance with claim 62, wherein the method comprises the further steps of: adding oil and pigment to the first container after the contents of the second container are added to the first container.

64.A mollusc coating marine growth inhibitor substantially as herein described, with reference to the Examples. method for treating molluscs substantially as herein described, with reference to the Examples. Dated this THIRTY-FIRST day of March 2006 Blue Lagoon Pearls Pty Ltd Applicant Wray Associates Perth, Western Australia Patent Attorneys for the Applicant(s)