WO2019081495A1

WO2019081495A1 - Self-polishing antifouling coating composition comprising alkoxysilane

Info

Publication number: WO2019081495A1
Application number: PCT/EP2018/079017
Authority: WO
Inventors: Marta Santiago REDONDO; Eduardo Andres MARTINEZ; Markus Hoffmann; Jeanine Claudia PICHLER
Original assignee: Hempel A/S
Priority date: 2017-10-23
Filing date: 2018-10-23
Publication date: 2019-05-02
Also published as: SG11202003346VA; CN111263793A; KR20200073248A; EP3700985A1

Abstract

The present invention relates to self-polishing antifouling coating compositions comprising a non-silicone-based binder matrix, a metal compound and one or more alkoxysilane(s). The present invention also relates to a marine structure coated with the self-polishing antifouling composition and to the coat itself.

Description

SELF-POLISHING ANTIFOULING COATING COMPOSITION COMPRISING ALKOXYSILANE

FIELD OF THE INVENTION The present invention relates to self-polishing antifouling coating compositions comprising a non-silicone-based binder matrix, a metal compound and one or more alkoxysilane(s). The present invention also relates to a marine structure coated with the self-polishing antifouling composition and to the coat itself.

BACKGROUND OF THE INVENTION

It is known to use alkoxysilanes, such as for example tetraethoxysilane, in paints based on silyl binder systems in which the alkoxysilane function as water scavenger protecting the silyl binder against hydrolysis. It is also known to use alkoxysilanes in silyl-based paints as inorganic capping agents, crosslinking agents and precursors of silica gel networks, silicium oxide nanoparticles and catalyst supports with controlled porosity.

EP 3078715 describes a marine antifouling coating composition comprising a binder including a silyl ester polymer and a rosin or a derivative thereof, tralopyril or a salt thereof and a stabilizer including a carbodiimide and a silane, which preferably is tetraethoxysilane. It is reported that such compositions have greatly improved storage stability and that the degree of paint thickening is significantly reduced compared to when dehydrating agents such as CaS0₄ or molecular sieves are used.

The inventors of the present invention have surprisingly found that the use of alkoxysilanes in antifouling coating compositions based on non-silicone binder systems provides beneficial properties, which are not observed when used in the silyl-based binder systems and which have not been reported earlier in the prior art. BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to novel self-polishing antifouling compositions based on a new principle in that the present inventors have surprisingly found that the drying properties of a coating composition can be markedly improved when the coating composition comprises a non-silicone-based binder matrix which includes a rosin-based binder system, a metal compound selected from the group consisting of a metal oxide and a metal hydroxide and mixtures thereof, and one or more alkoxysilane(s). Moreover, the inventors have also surprisingly found that when applying said coating composition on a marine structure then the weathering properties, such as gloss retention and whitening properties, of the final coat is markedly improved as compared to a coat obtained from an identical coating composition but without any alkoxysilane. In a first aspect the present invention relates to a self-polishing antifouling composition comprising a) a non-silicone-based binder matrix which includes a rosin-based binder system, b) a metal compound selected from the group consisting of a metal oxide and a metal hydroxide and mixtures thereof, and c) one or more alkoxysilane(s).

In a second aspect the present invention is directed to a method of coating a marine structure by applying the coating composition of the present invention to at least part of the marine structure. In a third aspect the present invention is directed to a marine structure coated with the coating composition of the present invention. In particular the present invention is directed to a coated marine structure where the coat comprises a siloxane network which includes one or more chemical structures such as≡Si-OH and≡Si-0-Si≡.

Accordingly, in a fourth aspect the present invention is directed to a coat obtained by applying a coating composition of the present invention to at least part of the marine structure, said coat comprising a siloxane network which includes one or more chemical structures such as≡Si-OH and≡Si-0-Si≡. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows the whitening effect of the presence of various amounts of an alkoxysilane (tetraethyl orthosilicate (TEOS)) in model paints based on a non- aqueous dispersion binder system.

Figure 2 shows the gloss retention of the presence of various amounts of an alkoxysilane (tetraethyl orthosilicate (TEOS)) in model paints based on a nonaqueous dispersion binder system.

Figure 3 shows the whitening effect of the presence of 1 VS-% of an alkoxysilane (TEOS) in model paints based on either a non-aqueous dispersion binder system (Example 2bl without an alkoxysilane and Example 2b2 with an alkoxysilane) or a rosin-based binder system (Example 2al without an alkoxysilane and Example 2a2 with an alkoxysilane, Example 2cl without an alkoxysilane and Example 2c2 with an alkoxysilane).

Figure 4 shows the gloss effect of the absence or presence of 1 VS-% of an alkoxysilane (TEOS) in model paints based on a non-aqueous dispersion binder system (Example 2b) or a rosin-based binder system (examples 2a and 2c).

Figure 5 shows the results of the cosmetic property test after 7 months in sea conditions at Vilanova, Spain. Figure 6 shows the results of the cosmetic property test after 2 months in sea conditions in Korea.

Figure 7 shows the drying properties (Beck Koller test) of a paint based on nonaqueous dispersion binders with and without an alkoxysilane at room

temperature.

Figure 8 shows the drying properties (Wood Block Setting test) of a paint based on non-aqueous dispersion binders with and without an alkoxysilane at 5 degrees C. Figure 9 shows the missing whitening effect of the absence or presence of an alkoxysilane (TEOS) in model paints based on silylated acrylate binder.

Figure 10 shows the whitening effect of the presence of 0.5 and 1 VS-% of an alkoxysilane (tetrapropyl orthosilicate (TPOS)) in model paints based on a nonaqueous dispersion binder system .

Figure 11 shows the gloss retention of the absence or presence of various amounts of an alkoxysilane (tetrapropyl orthosilicate (TPOS)) in model paints based on a non-aqueous dispersion binder system.

Figure 12 shows the drying properties (Beck Koller test) of a paint based on nonaqueous dispersion binders with and without different alkoxysilanes at room temperature. DETAILED DESCRIPTION OF THE INVENTION

The antifouling coating composition

The present invention is directed to self-polishing antifouling compositions comprising a) a non-silicone-based binder matrix which includes a rosin-based binder system, b) a metal compound selected from the group consisting of a metal oxide and a metal hydroxide and mixtures thereof, and c) one or more alkoxysilane(s) . In most embodiments, the binder matrix constitutes 25-80 % by solids volume of the coating composition. In preferred embodiments, the binder matrix constitutes 20-70 % by solids volume, such as 18-55 % by solids volume of the coating composition. When expressed by dry weight, typically the binder matrix constitutes 18-75 % by dry weight of the coating composition . In preferred embodiments, the binder matrix constitutes 16-60 %, such as 15-40 %, by dry weight of the coating composition. In most practical embodiments, the rosin-based binder system constitutes 10-50 % by solids volume of the coating composition. In preferred embodiments, the rosin-based binder system constitutes 12-45 % by solids volume, such as 15-40 % by solids volume of the coating composition.

When expressed by dry weight, typically the rosin-based binder system constitutes 5-30 % by dry weight of the coating composition. In preferred embodiments, the rosin-based binder system constitutes 8-25 %, such as 10-25 %, by dry weight of the coating composition.

In most embodiments, the metal compound constitutes 1-50% by solids volume of the coating composition. In some embodiments, the metal compound constitutes 1-30%, such as 1-20% or 1-15% or 1-5% by solids volume of the coating composition. In other embodiments the metal compound constitutes 2- 40%, for example 3-25% such as 5-15% or 8-12% by solids volume of the coating composition.

In most embodiments, the alkoxysilane constitutes 0.05-20%, such as 0.1-10%, preferably 0.2-5%, such as 0.3-2% by solids volume of the coating composition. In other embodiments, the alkoxysilane constitutes 0.05-2%, for example 0.08- 1.5%, such as 0.1-1% by solids volume of the coating composition.

In some embodiments the ratio between alkoxysilane and rosin is for example 1- 300, such as 1-150, preferably 1-80, most preferably 1-40 in solids volume.

In some embodiments a non-aqueous dispersion binder system is present in the binder matrix in addition to the rosin-based binder system. In such cases the ratio between non-aqueous dispersion binder (NAD) and rosin is for example 1-20, such as 1-10, preferably 1-5, most preferably 2-3 in solids volume.

In some embodiments an acrylic binder system is present in the binder matrix in addition to the rosin-based binder system, and in such embodiments the ratio between acrylic binder and rosin is for example 1-50, such as 1-20, preferably 1- 10, most preferably 1-7 in solids volume. In most embodiments the coating composition also comprises a certain amount of biocides. Typically, the amount of the biocide is 3-45 %, such as 5-40 %, e.g. 7- 38 %, or 10-35 %, or 15-35 %, by solids volume of the coating composition. When expressed by dry weight, the amount of the biocide is typically 3-65 %, such as 5-60 %, e.g. 10-60 %, or 15-60 %, or 15-40 %, or 20-60 %, by dry weight of the coating composition.

The binder matrix The binder matrix of the coating composition forms the paint film upon drying/curing and thereby corresponds to the continuous phase of the final (dry) paint coat.

The binder systems applicable in the non-silicone-based binder matrix are self- polishing non-silicone-based binder systems.

When used herein, the term "self-polishing" is intended to mean that the paint coat (i.e. the dried/cured film of the coating composition) should have a polishing rate of at least 1 μιη per 10,000 Nautical miles (18,520 km) determined in accordance with the "Polishing rate test" specified in the Examples section.

The term "non-silicone-based binder matrix" is intended to refer to a binder matrix in which the amount of non-silicone binders constitutes at least 35% by solids volume of the binder matrix. In some embodiments the amount of non- silicone binders constitutes 40% or 45% or 50% or 55% or 60% or 65% or 70% or 75% or 80% or 85% or 90% or 95% or 100% by solids volume of the binder matrix.

Suitable examples of non-silicone binders include rosin binders, non-aqueous dispersion binders, metal acrylate binders, hybrids of silylated acrylate and metal acrylate binders, polyoxalate binders, zwitterion binders, hybrids of silylated acrylate and zwitterion binders and polyester binder and any mixtures thereof.

In particular, the amount of silicone-based binders, such as for example silylated acrylate binders, constitutes at most 10% by solids volume of the non-silicone- based binder matrix. In some embodiments, silylated acrylate binders constitute at most 8% or 6% or 4% or 2% by solids volume of the binder matrix. In other embodiments, silylated acrylate binders constitute at most 1% such as 0.75% for example 0.5% or 2.5% by solids volume of the binder matrix. In yet another embodiment the non-silicone binder matrix does not contain any silylated acrylate binders.

Preferably, the polishing rate is in the range of 1-50 μιη, in particular in the range of 1-30 μιη, per 10,000 Nautical miles (18,520 km). It is envisaged that all self-polishing binder systems conventionally used in "self- polishing" coating compositions may be used as the binder system of the present coating composition with the one exception that the binder matrix constitutes at most 10 % of silylated acrylate binders by solids volume of the binder matrix. It is also found that with respect to the relative amounts of binder system vs. pigments/fillers/etc. , only minor modifications (optimizations) may be necessary in order to obtain suitable polishing rates with respect to the marine environment to which the paint coat will be exposed. For the purpose of illustrating the scope of the present invention with respect to possible types of binder systems, a number of examples of binder systems for marine purposes and yacht purposes, are provided in the following.

The applicable binder systems are all self-polishing non-silicone-based binder system. It has been found, however, that the coating compositions according to the present invention perform best when a rosin-based binder system forms part of the binder matrix.

In most embodiments the non-silicone-based binder matrix includes an additional non-silicone-based binder system in addition to the rosin-based binder system. It is believed that the following additional binder systems are especially interesting: non-aqueous dispersion binder systems, metal acrylate binder system, hybrids of silylated acrylate and metal acrylate binder systems, polyoxalate binder systems, zwitterion binder systems, hybrids of silylated acrylate and zwitterion binder systems and polyester binder system. For marine purposes it is believed that non-aqueous dispersion based binder systems and metal-acrylate based binder systems are especially interesting.

Some of these binder systems will - for illustrative purposes - be described in further detail in the following.

The term "rosin-based binder system" is intended to refer to any type of rosin- based binder system as described in further details below including any mixtures of rosin constituents as further described below.

The term "non-silicone-based binder system" is intended to refer to any type of non-silicone-based binder system, such as for example the binder systems mentioned below, i.e. rosin-based binder systems, non-aqueous dispersion binder systems, metal acrylate binder systems, hybrids of silylated acrylate and metal acrylate binder systems, polyoxalate binder systems, zwitterion binder systems, hybrids of silylated acrylate and zwitterion binder systems and polyester binder systems. The term also encompasses any compatible mixtures of such defined non-silicone-based binder systems. The rosin-based binder system

The rosin-based binder system is based on rosin and/or rosin derivatives.

Examples of constituents of such a rosin-based binder system are rosin, rosin derivatives such as for example metal salts of carboxylated rosin i.e. resinates.

The terms "rosin", "resinate" and the like is intended to refer to gum rosin; wood rosin of grades B, C, D, E, F, FF, G, H, I, J, K, L, M, N, W-G, W-W (as defined by the ASTM 0509 standard); virgin rosin; hard rosin; yellow dip rosin; NF wood rosin; tall oil rosin; or colophony or colophonium. The terms "rosin" and "resinate" and the like are also intended to include suitable types of modified rosin, in particular oligomerisation; hydrogenation; dehydrogenation

hydrogenation/disproportionation/dismutation; etc., that will reduce the amount of conjugated non-aromatic double bonds. It should be understood that the group of further binder components may include polymeric flexibilisers such as those generally and specifically defined in WO 97/44401 that is hereby incorporated by reference. Non-aqueous dispersion binder systems

The terms "non-aqueous dispersion resin", "NAD" and similar expressions are intended to mean a shell-core structure that includes a resin obtained by stably dispersing a high- polarity, high-molecular weight resin particulate component (the "core component") into a non-aqueous liquid medium in a low-polarity solvent using a high-molecular weight component (the "shell component").

The non-aqueous dispersion resin may be prepared by a method wherein a polymerisable ethylenically unsaturated monomer which is soluble in a hydrocarbon solvent and which is polymerisable to form a polymer (the core component) which is insoluble in the hydrocarbon solvent, is subjected to dispersion polymerisation in accordance with a conventional method in the hydrocarbon solvent in the presence of a shell component (the dispersion stabiliser) made of a polymer which dissolves or swells in the solvent.

The non-aqueous dispersion-type resin utilised in this invention can be a resin known per se; or it can be produced like the known resins. Such non-aqueous dispersion-type resins and method for their preparation are described in, e.g., US 3,607,821, US 4,147,688, US 4,493,914 and US 4,960,828, Japanese Patent Publication No. 29,551/1973 and Japanese Laid-open Patent Application No.

177,068/1982. Specifically, as the shell component constituting the non-aqueous dispersion-type resin, various high-molecular substances soluble in a low-polarity solvent which are described in, e.g., US 4,960,828 (Japanese Laid- open Patent Application No. 43374/1989), can be used.

From the aspect of antifouling property of the final paint coat, shell components such as an acrylic resin or a vinyl resin may be used.

As the core component, a copolymer of an ethylenically unsaturated monomer having a high polarity is generally applicable. Preferably the core component of the non-aqueous dispersion-type resin has free acid groups or silyl ester groups that are convertible into the acid group by hydrolysis in sea water or combinations thereof. Preferably 5-75 % by weight, e.g. 5-60 % by weight or 7-50 % by weight, of the monomers of the core polymer should carry free acid groups or silyl ester groups or combinations thereof. As the free acid groups will have direct influence on the properties of the paint formulation, whereas the silyl ester groups will only have influence after hydrolysis in seawater, it is presently preferred to have an overweight of free acid groups.

Examples of silyl ester monomers are silyl esters of acrylic or methacrylic acid.

If desired, a smaller proportion of the free acid groups or silyl ester groups may also be contained in the shell component.

The expression "free acid group" is intended to cover the acid group in the acid form. It should be understood that such acid groups temporarily may exist on salt form if a suitable counter ion is present in the composition or in the environment. As an illustrative example, it is envisaged that some free acid groups may be present in the sodium salt form if such groups are exposed to salt water.

Preferably the non-aqueous dispersion-type resin has a resin acid value of usually 15-400 mg KOH/g, preferably 15 to 300 mg KOH/g, such as 18 to 300 mg KOH/g. If the total acid value of the NAD resin is below 15 mg KOH/g, the polishing rate of the paint coat is too low and the antifouling property will often be

unsatisfactory. On the other hand, if the total acid value is above 400 mg KOH/g, the polishing rate is too high for that reason a problem of water resistance (durability of the paint coat in seawater) becomes a problem. (When the core component and/or the shell component contain the acid precursor group, the resin acid value is one given after the group is converted into the acid group by hydrolysis). The "resin acid value" here referred to is an amount (mg) of KOH consumed to neutralise 1 g of a resin (solids content), expressing a content of an acid group (in case of the acid precursor group, a content of an acid group formed by hydrolysis) of the resin (solids content).

It is advisable that the acid group and/or the acid precursor group is contained in the core component such that the content thereof is, as a resin acid value, at least 80 %, preferably at least 90 %, more preferably at least 95 % of the total resin acid value of the non-aqueous dispersion-type resin. This being said, it is normally preferred that the shell component is hydrophobic. The dry weight ratio of the core component to the shell component in the NAD resin is not especially limited, but is normally in the range of 90/10 to 10/90, preferably 80/20 to 25/75, such as 60/40 to 25/75. Silylated acrylate binder system

In some embodiments of the present invention the binder matrix may comprise a silylated acrylate binder system, which constitutes at most 10% by solids volume of the binder matrix.

The silylated acrylate binder system comprises a silylated acrylate co-polymer having at least one side chain bearing at least one terminal group of the general formula (I) :

wherein n is an integer of 0, 1, 2, etc., and X is -C(=0)-, and Ri, R₂, R3, R4 and are as defined below.

While n is an integer of 0, 1, 2, 3, 4 or more, it is in these cases preferred that n is 0-100, e.g. 0-50, such as 0 or 1 or 2 or 2-15. R₁- R5 are each groups

independently selected from the group consisting of Ci-₂o-alkyl (e.g. methyl, ethyl, propyl, butyl and cycloalkyl, such as cyclohexyl); aryl, such as phenyl and naphthyl and substituted aryl, such as substituted phenyl and substituted naphthyl. Examples of substituents for aryl are halogen, Ci-5-alkyl, Ci-10- alkylcarbonyl, sulphonyl, nitro, and amino. Typically, R₁-R5 are each groups independently selected from Ci_₈-alkyl, phenyl and substituted phenyl. It is generally preferred that each of the alkyl groups has up to about 5 carbon atoms (Ci-5-alkyl). As indicated above, R1- R5 may be the same or different groups.

Monomers comprising the terminal groups of the general formula I above may be synthesised as described in EP 0 297 505 Bl.

Such monomers may (in order to obtain a co-polymer) be co-polymerised with a vinyl polymerisable monomer. Examples of suitable vinyl polymerisable monomers include methacrylate esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate and methoxy ethyl methacrylate; acrylate esters such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate; maleic acid esters such as dimethyl maleate and diethyl maleate; fumaric acid esters such as dimethyl fumarate and diethyl fumarate; styrene, vinyl toluene, α-methylstyrene, vinyl chloride, vinyl acetate, butadiene, acrylamide, acrylonitrile, methacrylic acid, acrylic acid, isobornyl methacrylate and maleic acid.

The amount of vinyl polymerisable monomers is not more than 95 % by weight of the total weight of the resulting co-polymer, preferably not more than 90 % by weight. Accordingly, the amount of monomers comprising the terminal groups of the general formula I above is at least 5 % by weight, in particular at least 10 % by weight.

The co-polymers preferably have weight average molecular weights in the range of 1,000-1,500,000, such as in the range of 5,000-1,500,000, e.g. in the range of 5,000-1,000,000, in the range of 5,000-500,000, in the range of 5,000-250,000, or in the range of 5,000-100,000.

In another interesting embodiment of the invention the binder system to be used in the coating composition according to the invention comprises a silylated acrylate copolymer having at least one side chain bearing at least one terminal group of the general formula II (i.e. formula I wherein n=0) : R₃

__x_₀__Si_R₄ (II)

rig wherein X, R₃, R₄ and R₅ are as defined above.

Examples of monomers having a terminal group of the general formula II (shown above) are acid functional vinyl polymerisable monomers, such as monomers derived from acrylic acid, methacylic acid, maleic acid (preferably in the form of a monoalkyi ester with 1-6 carbon atoms) or fumaric acid (preferably in the form of a monoalkyi ester with 1-6 carbon atoms). Thus, specific examples of a suitable triorganosilyl group (i.e. the -Si(R₃)(R₄)(R₅) group) shown in the general formula I or II include trimethylsilyl, triethylsilyl, tri- n-propylsilyl, tri-n-butylsilyl, tri-/so-propylsilyl, tri-n-pentylsilyl, tri-n-hexylsilyl, tri-n-octylsilyl, tri-n-dodecylsilyl, triphenylsilyl, tri-p-methylphenylsilyl, tribenzylsilyl, tri-2-methylisopropylsilyl, tri-tert-butyl-silyl, ethyldimethylsilyl, n- butyldimethylsilyl, di-/so-propyl-n-butylsilyl, n-octyl-di-n-butylsilyl, di-/so- propyloctadecylsilyl, dicyclohexylphenylsilyl, tert-butyldiphenylsilyl,

dodecyldiphenyl-silyl and diphenylmethylsilyl.

Specific examples of suitable methacrylic acid-derived monomers bearing at least one terminal group of the general formula I or II include trimethylsilyl

(meth)acrylate, triethyl-silyl(meth)acrylate, tri-n-propylsilyl(meth)acrylate, triisopropylsilyl (meth)acrylate, tri-n-butylsilyl (meth)acrylate, triisobutylsilyl (meth)acrylate, tri-tert-butylsilyl(meth)acrylate, tri-n-amylsilyl (meth)acrylate, tri-n-hexylsilyl (meth)acrylate, tri-n-octylsilyl (meth)acrylate, tri-n-dodecylsilyl (meth)acrylate, triphenylsilyl (meth)acrylate, tri-p-methylphenylsilyl (meth)- acrylate, tribenzylsilyl (meth)acrylate, ethyldimethylsilyl (meth)acrylate, n- butyldimethylsilyl (meth)acrylate, diisopropyl-n-butylsilyl (meth)acrylate, n- octyldi-n-butylsilyl (meth)acrylate, diisopropylstearylsilyl (meth)acrylate, dicyclohexylphenylsilyl (meth)acrylate, t-butyldiphenyl-silyl (meth)acrylate, and lauryldiphenylsilyl (meth)acrylate.

Specific examples of suitable maleic acid-derived and fumaric acid-derived monomers bearing at least one terminal group of the general formula I or II include triisopropylsilyl methyl maleate, triisopropylsilyl amyl maleate, tri-n- butylsilyl n-butyl maleate, tert-butyldiphenylsilyl methyl maleate, t- butyldiphenylsilyl n-butyl maleate, triisopropylsilyl methyl fumarate,

triisopropylsilyl amyl fumarate, tri-n-butylsilyl n-butyl fumarate, tert- butyldiphenylsilyl methyl fumarate, and tert-butyldiphenylsilyl n-butyl fumarate.

In an interesting embodiment of the present invention, the co-polymer to be used in the binder system comprises monomer units with a terminal group of the general formulae I and II (as discussed above) in combination with a second monomer B of the general formula III:

Y-(CH(R_A)-CH(R_B)-0)_p-Z (III) wherein Z is a Ci-₂o-alkyl group or an aryl group; Y is an acryloyloxy group, a methacryloyloxy group, a maleinoyloxy group or a fumaroyloxy group; R_A and R_B are independently selected from the group consisting of hydrogen, Ci_₂o-alkyl and aryl; and p is an integer of 1 to 25. If p> 2, R_A and R_B are preferably hydrogen or CH₃, i.e. if p>2 the monomer B is preferably derived from a polyethylene glycol or a polypropylene glycol.

If p=l it is contemplated that monomers, wherein R_A and R_B are larger groups, such as Ci-2o-alkyl or aryl, may also be useful for the purposes described herein.

As shown in formula III, monomer B has in its molecule an acryloyloxy group, a methacryloyloxy group, a maleinoyloxy group (preferably in the form of a mono- Ci-6-alkyl ester), or a fumaroyloxy group (preferably in the form of a mono-Ci-₆- alkyl ester) as an unsaturated group (Y) and also alkoxy- or aryloxypolyethylene glycol. In the alkoxy- or aryloxypolyethylene glycol group, the degree of polymerisation (p) of the polyethylene glycol is from 1 to 25.

Specific examples of monomer B which has a (meth)acryloyloxy group in a molecule include methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, hexoxyethyl

(meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, and

ethoxytriethylene glycol (meth)acrylate.

Specific examples of monomer B which has a maleinoyloxy or fumaroyloxy group in a molecule include methoxyethyl n-butyl maleate, ethoxydiethylene glycol methyl maleate, ethoxytriethylene glycol methyl maleate, propoxydiethylene glycol methyl maleate, butoxyethyl methyl maleate, hexoxyethyl methyl maleate, methoxyethyl n-butyl fumarate, ethoxydiethylene glycol methyl fumarate, ethoxytriethylene glycol methyl fumarate, propoxydiethylene glycol methyl fumarate, butoxyethyl methyl fumarate, and hexoxyethyl methyl fumarate.

As will be understood by the person skilled in the art, other vinyl monomers may be incorporated in the resulting co-polymer comprising either monomer units having a terminal group of the general formulae I or II (shown above) or in the resulting co-polymer comprising monomer units having a terminal group of the general formulae I or II (shown above) in combination with the second monomer B of the formula III (shown above).

With respect to other monomers co-polymerisable with the above-mentioned monomers, use may be made of various vinyl monomers such as the vinyl polymerisable monomers (A) discussed above.

It is preferred that the proportion of the monomer having a terminal group of the general formulae I or II is from 1-95 % by weight, that of monomer B is from 1- 95 % by weight, and that of other monomer(s) co-polymerisable therewith is from 0-95 % by weight on the basis of the total weight of the monomers.

The molecular weight of the resulting co-polymer thus obtained is desirably in the range of 1,000-150,000, such as in the range of 3,000-100,000, e.g. in the range of 5,000-100,000 in terms of weight-average molecular weight.

In a further interesting embodiment of the present invention, the binder system to be used in the coating composition according to the invention comprises a copolymer having monomer units with a terminal group of the general formulae I or II (as discussed above) in combination with a second monomer C of the general formula IV: Y— CH (IV) O ₇ wherein Y is an acryloyloxy group, a methacryloyloxy group, a maleinoyloxy group or a fumaroyloxy group, and both of R₅ and R₇ are Ci-i₂-alkyl .

As shown in formula IV, monomer C has in its molecule an acryloyloxy group, a methacryloyloxy group, a maleinoyloxy group (preferably in the form of a mono- Ci-6-alkyl ester), or a fumaroyloxy group (preferably in the form of a mono-Ci-₆- alkyl ester) as an unsaturated group (Y) and also a hemi-acetal group.

Monomer C can be prepared by an ordinary addition reaction of a carboxy group- containing vinyl monomer selected from acrylic acid, methacrylic acid, maleic acid (or monoester thereof), and fumaric acid (or monoester thereof), with an alkyl vinyl ether (e.g . ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, and 2-ethylhexyl vinyl ether), or a cycloalkyl vinyl ether (e.g . cyclohexyl vinyl ether) .

As will be understood by the person skilled in the art, other vinyl monomers may be incorporated in the resulting co-polymer comprising monomer units having a terminal group of the general formulae I or II (shown above) in combination with the second monomer C of the formula IV (shown above) .

It is preferred that the proportion of the monomer having a terminal group of the general formulae I or II is from 1-95 % by weight (preferably from 1-80 % by weight), that of monomer C is from 1-95 % by weight (preferably from 1-80 % by weight), and that of other monomer(s) co-polymerisable therewith is up to 98 % by weight on the basis of the total weight of the monomers.

The molecular weight of the co-polymer is desirably in the range of 1,000- 150,000, preferably in the range of 3,000-100,000, such as in the range of 5,000- 100,000 in terms of weight-average molecular weight.

Metal acrylate binder systems

In an interesting embodiment of the invention the binder system to be used in the coating composition according to the invention comprises a metal acrylate copolymer having at least one side chain bearing at least one terminal group of the general formula V:

-X-0-M-(L)_n (V) wherein X is -C(=0)-, -S(=0)₂-, -P(=0)(OH)-; M is a metal having a valency of 2 or more; n is an integer of 1 or more with the proviso that n + 1 equals the metal valency; L is an organic acid residue and each L is independently selected from the group consisting of

S O

II II II

S— C— R4 - O— C— F O— C— (¾ · O— ¾ · o

II

— S™F¾ and .— Ra il

o

wherein R₄ is a monovalent organic residue, or L is -OH or combinations thereof; R₃ is hydrogen or a hydrocarbon group having from 1 to 10 carbon atoms.

Examples of monomers having a terminal group of the general formulae V (shown above) are acid-functional vinyl polymerisable monomers, such as methacrylic acid, acrylic acid, p-styrene sulfonic acid, 2-methyl-2-acrylamide propane sulfonic acid, methacryl acid phosphoxy propyl, methacryl 3-chloro-2-acid phosphoxy propyl, methacryl acid phosphoxy ethyl, itaconic acid, maleic acid, maleic anhydride, monoalkyl itaconate (e.g. methyl, ethyl, butyl, 2-ethyl hexyl), monoalkyl maleate (e.g. methyl, ethyl, butyl, 2-ethyl hexyl) ; half-ester of acid anhydride with hydroxyl containing polymerisable unsaturated monomer (e.g. half-ester of succinic anhydride, maleic anhydride or phthalic anhydride with 2- hydroxy ethyl methacrylate. The above-mentioned monomers may be co-polymerised in order to obtain the co-polymer with one or more vinyl polymerisable monomers. Examples of such vinyl polymerisable monomers are methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, octyl acrylate, octyl methacrylate, 2-ethyl hexyl acrylate, 2- ethyl hexyl methacrylate, methoxy ethyl methacrylate, styrene, vinyl toluene, vinyl pyridine, vinyl pyrolidone, vinyl acetate, acrylonitrile, methacrylonitrile, dimethyl itaconate, dibutyl itaconate, di-2-ethyl hexyl itaconate, dimethyl maleate, di (2-ethyl hexyl) maleate, ethylene, propylene and vinyl chloride.

With respect to the ligand (L), each individual ligand is preferably selected from the group consisting of

S O S

1! II li

S— C— R4 ' ^■— O— C— f¾ > O— C— F — O—

O II

— S— R4 and — O— S— FV wherein R₄ is a monovalent organic residue.

Preferably, R₄ is selected from the group consisting of

wherein R₅ is hydrogen or a hydrocarbon group having from 1 to 20 carbon atoms; R₅ and R₇ each independently represents a hydrocarbon group having from 1 to 12 carbon atoms; R₈ is a hydrocarbon group having from 1 to 4 carbon atoms; and R₉ is cyclic hydrocarbon group having from 5 to 20 carbon atoms, such as abietic acid, pallustric acid, neoabietic acid, levopimaric acid,

dehydroabietic acid, pimaric acid, isopimaric acid, sandaracopimaric acid and A8,9-isopimaric acid. Examples of compounds which may be used as ligands are:

(1) Compounds comprising the group

O

II

-o—c- e.g. aliphatic acids, such as levulinic acid; alicyclic acids, such as naphthenic acid, chaulmoogric acid, hydnocarpusic acid, neo abietic acid, levo pimaric acid, palustric acid, 2-methyl-bicyclo-2,2,l-heptane-2-carboxylic acid; aromatic carboxylic acids such as salicylic acid, cresotic acid, α-naphthoic acid, β-naphthoic acid, p-oxy benzoic acid; halogen containing aliphatic acids, such as monochloro acetic acid, monofluoro acetic acid; halogen containing aromatic acids, such as 2,4,5-trichloro phenoxy acetic acid, 2,4-dichloro phenoxy acetic acid, 3,5-dichloro benzoic acid; nitrogen-containing organic acids, such as quinoline carboxylic acid, nitro benzoic acid, dinitro benzoic acid, nitronaphthalene carboxylic acid; lactone carboxylic acids, such as pulvinic acid, vulpinic acid; uracil derivatives, such as uracil-4-carboxylic acid, 5-fluoro uracil-4-carboxylic acid, uracil-5-carboxylic acid; penicillin-derived carboxylic acids, such as penicillin V, ampicillin, penicillin BT, penicillanic acid, penicillin G, penicillin O; Rifamycin B, Lucensomycin, Salcomycin, chloroamphenicol, variotin, Trypacidine; and various synthetic fatty acids.

(2) Compounds comprising the group __s_jj

e.g. dimethyl dithiocarbamate and other dithiocarbamates.

(3) Compounds comprising the group

O II

II

O e.g. sulphur containing aromatic compounds, such as l-naphthol-4-sulphonic acid, p-phenyl benzene sulphonic acid, β-naphthalene sulphonic acid and quinoline sulphonic acid. (4) Compounds comprising the group— S— , such as compounds comprising the following groups

(5) Compounds comprising the group

S

II

— o— c— such as various thiocarboxylic compounds.

(6) Compounds comprising the group -O- or -OH, e.g. phenol, cresol, xylenol, thymol, carvacol, eugenol, isoeugenol, phenyl phenol, benzyl phenol, guajacol, butyl stilbene, (di) nitro phenol, nitro cresol, methyl salicylate, benzyl salicylate, mono-, di-, tri-, tetra- and penta-chlorophenol, chlorocresol, chloroxylenol, chlorothymol, p-chloro-o-cyclo-hexyl phenol, p-chloro-o-cyclopentyl phenol, p- chloro-o-n-hexyl phenol, p-chloro-o-benzyl phenol, p-chloro-o-benzyl-m-cresol and other phenols; β- naphthol, 8-hydroxy quinoline.

With respect to the metal (M), any metal having a valency of 2 or more may be used. Specific examples of suitable metals include Ca, Mg, Zn, Cu, Ba, Te, Pb, Fe, Co, Ni, Bi, Si, Ti, Mn, Al and Sn. Preferred examples are Co, Ni, Cu, Zn, Mn, and Te, in particular Cu and Zn. When synthesising the metal-containing co-polymer, the metal may be employed in the form of its oxide, hydroxide or chloride. The co-polymer to be used in the binder system in the coating composition according to the invention may be prepared as described in e.g. EP 0 471 204 Bl, EP 0 342 276 Bl or EP 0 204 456 Bl. Monomers comprising the terminal groups of the general formula V above may be co-polymerised (in order to obtain the co-polymer) with other polymerisable unsaturated monomers, any customarily used ethylenically unsaturated monomer may be used. Examples of such monomers are methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, octyl acrylate, octyl

methacrylate, 2-ethyl hexyl acrylate, 2-ethyl hexyl methacrylate, methoxy ethyl methacrylate, styrene, vinyl toluene, vinyl pyridine, vinyl pyrolidone, vinyl acetate, acrylonitrile, methacrylo nitrile, dimethyl itaconate, dibutyl itaconate, di- 2-ethyl hexyl itaconate, dimethyl maleate, di (2-ethyl hexyl) maleate, ethylene, propylene and vinyl chloride. One particular type of co-monomers is acrylic or methacrylic esters wherein the alcohol residue includes a bulky hydrocarbon radical or a soft segment, for example a branched alkyl ester having 4 or more carbon atoms or a cycloalkyl ester having 6 or more atoms, a polyalkylene glycol monoacrylate or monomethacrylate optionally having a terminal alkyl ether group or an adduct of 2-hydroxyethyl acrylate or methacrylate with caprolactone, e.g. as described in EP 0 779 304 Al .

If desired, hydroxy-containing monomers, such as 2-hydroxy ethyl acrylate, 2- hydroxy ethyl methacrylate, 2-hydroxy propyl acrylate, 2-hydroxy propyl methacrylate may also be used.

It should be noted that in the resulting co-polymer, not all the organic acid side groups need to contain a metal ester bond; some of the organic acid side groups may be left un-reacted in the form of free acid, if desired.

The weight average molecular weight of the metal-containing co-polymer is generally in the range of from 1,000 to 150,000, such as in the range of from 3,000 to 100,000, preferably in the range of from 5,000 to 60,000.

In another interesting embodiment of the invention the coating composition further comprises an amount of an organic ligand at least equal to the ligand-to- metal co-ordination ratio of 1 : 1, said organic ligand being selected from the group consisting of aromatic nitro compounds, nitriles, urea compounds, alcohols, phenols, aldehydes, ketones, carboxylic acids and organic sulphur compounds, whereby the co-polymer defined above forms a polymer complex with the organic ligand in situ.

Examples of monobasic organic acids usable for forming the hybrid salt include monocarboxylic acids such as acetic, propionic, butyric, lauric, stearic, linolic, oleic, naphthenic, chloroacetic fluoroacetic, abietic, phenoxyacetic, valeric, dichlorophenoxyacetic, benzoic or napthoic acid; and monosulphonic acids such as benzenesulphonic acid, p-toluenesulphonic acid, dodecylbenzenesulphonic acid, naphthalenesulphonic or p- phenylbenzenesulforic acid.

A preferred method for producing the polymeric hybrid salt has been disclosed in Japanese Patent Kokai No. 16809/1989.

Hybrids of silylated acrylate and metal acrylate binder systems

An intriguing further example of an interesting binder is that being based on silyl acrylate monomers (as those described further above) as well as metal acrylate monomers (as those described further above) . Such binders are described e.g. in KR 20140117986.

Polyoxalate binder systems

A further example of an interesting binder is that based on polyoxalates, e.g. as disclosed in WO 2015/114091.

The polyoxalates may be linear or branched polymers. It is the copolymer formed from at least three different monomers, e.g. a random copolymer or block copolymer. It will be appreciated that any polyoxalate comprises sufficient repeating units in order to achieve a molecular weight of at least 4000 g/mol.

The polyoxalates can be prepared by condensation polymerisation using any of various methods known and used in the art.

The polyoxalate is preferably formed from polymerisation of an oxalate monomer, selected from oxalic acid or a diester derivative thereof and at least two further monomers. Preferably the second monomer is selected from the group of a cyclic diacid and a cyclic diester and the third monomer is a diol.

The oxalate monomer used in the polymerisation reaction is oxalic acid or a diester derivative thereof. Esters may be alkyl esters, alkenyl esters, cycloalkyl esters or aryl esters. Preferably, the oxalate monomer is selected from the group of oxalic acid and dialkyl oxalates. Examples of dialkyl oxalates include dimethyl oxalate, diethyl oxalate, dipropyl oxalate and dibutyl oxalate. In addition to the oxalate monomer, the polyoxalate comprises a second monomer selected from the group of a cyclic diacid and a cyclic diester. Examples of a cyclic diacid are dicarboxylic acids of a saturated, unsaturated or aromatic C₃- C₈ ring, such as a C₅-C₆ ring, optionally comprising one or more heteroatoms selected from the group consisting of N, O and S. Examples of heterocyclic rings include furan (e.g. giving the compound furan-2,5-dicarboxylic acid) . Examples of cyclic diesters are esterified cyclic dicarboxylic acids of a saturated, unsaturated or aromatic C₃-C₈ ring, such as a C₅-C₅ ring, optionally comprising one or more heteroatoms selected from the group consisting of N, O and S. The polyoxalate also comprises a third monomer which is a diol. There can be one diol monomer or more than one diol monomer. The use of two or three monomers is envisaged. Examples of diols include saturated aliphatic and saturated cycloaliphatic diols, unsaturated aliphatic diols and aromatic diols. Saturated aliphatic and cycloaliphatic diols may be preferred. Also mixtures of saturated aliphatic and saturated cycloaliphatic diols can be used.

See further in WO 2015/114091 for details about such polyoxalate binder systems. Zwitterion binder systems and hybrids of silylated acrylate and zwitterion binder systems

A still further example of an interesting binder is that based on polymer binders having zwitterion monomers possibly combined with silyl acrylate monomers, e.g. as disclosed in WO 2004/018533 and WO 2016/066567. A suitable zwitterion binder system is disclosed in WO 2004/018533. It includes a polymer comprising quaternary ammonium groups and/or quaternary

phosphonium groups bound (pendant) to the backbone of the polymer, said quaternary ammonium groups and/or quaternary phosphonium groups being neutralized, in other words blocked or capped, by counter-ions. These counter- ions consists of the anionic residue of an acid having an aliphatic, aromatic or alkaryl hydrocarbon group comprising at least 6 carbon atoms.

The polymers can be prepared by polymerisation of at least one type of long-chain acid-capped quaternary-functional monomer. Alternatively it can be prepared by reaction of a polymer containing quaternary ammonium groups and/or quaternary phosphonium groups with an acid having an aliphatic, aromatic, or alkaryl hydrocarbon group comprising 6 or more carbon atoms. See further in WO 2004/018533 for details about such zwitterion binder systems.

A suitable hybrid of silylated acrylate and zwitterion binder system is disclosed in WO 2016/066567. It includes a polymer comprising a silyl ester group and quaternary ammonium groups and/or quaternary phosphonium groups, where said quaternary ammonium groups and/or quaternary phosphonium groups are neutralized by counter-ions and where said counter-ions consist of the conjugate base of an acid having an aliphatic, aromatic or alkaryl hydrocarbyl group. The silyl ester groups and/or the quaternary ammonium groups and/or quaternary phosphonium groups may be located on side chains pendant to the polymer backbone or alternatively in the backbone of the polymer itself.

The polymer is obtainable by polymerizing monomers comprising silyl ester group(s) and monomers comprising the quaternary ammonium group(s) and/or quaternary phosphonium group(s), where the quaternary ammonium groups and/or quaternary phosphonium groups are neutralized by counter-ions and where said counter-ions consist of the conjugate base of an acid having an aliphatic, aromatic or alkaryl hydrocarbyl group and optionally other monomers. The polymer may be a (meth)acrylic polymer. See further in WO 2016/066567 for details about such hybrid of silylated acrylate and zwitterion binder systems. Polyester binder systems

An even further example of an interesting binder is that based on polyesters, e.g. as disclosed in US 2015/0141562.

The polyester resin may be obtained by reacting a) a trihydric or greater alcohol, b) a dibasic acid or its anhydride and c) a divalent alcohol and then further reacting with d) an alicyclic dibasic acid or its anhydride. The trihydric or greater alcohol may be an alcohol having 3 or more hydroxyl groups in the molecule, examples of which include polyfunctional polyhydroxy compounds such as glycerin, trimethylolethane, trimethylolpropane,

trimethylolbutane, hexanetriol and pentaerythritol. The number of carbon atoms is preferably 3-24 such as 3-8.

The dibasic acid or its anhydride is an acid with two or more ionizable hydrogen atoms in the molecule, or an anhydride thereof, examples of which include aliphatic dibasic acids, alicyclic dibasic acids, aromatic dibasic acids and their anhydrides. Specific example for the aliphatic dibasic acid or its anhydride include malonic acid, maleic acid, fumaric acid, glutaric acid, succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonamethylene- dicarboxylic acid, 1,10-decamethylenedicarboxylic acid, 1,11-undecamethylene- dicarboxylic acid and 1,12-dodecamethylenedicarboxylic acid and their anhydrides. Specific examples for the alicyclic dibasic acid or its anhydride include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4- cyclohexanedicarboxylic acid, 1,4-decahydronaphthalenedicarboxylic acid, 1,5- decahydronaphthalenedicarboxylic acid, 2,6-decahydronaphthalenedicarboxylic acid and 2,7-decahydronaphthalenedicarboxylic acid and their anhydrides. Further specific examples for the aromatic dibasic acid or its anhydride include

orthophthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, anthracenedicarboxylic acid, dimer acid, hydrogenated dimer acid and phenanthrenedicarboxylic acid as well as their anhydrides. These may naturally be used in various derivative forms (for example dimethyl carboxylate ester or sodium-5-sulfoisophthalic acid) and two or more different ones may also be used as mixtures. The divalent alcohol is an alcohol having two hydroxyl groups in the molecule. Specific examples include ethylene glycol, 1,2 propylene glycol, 1,3 propylene glycol, 1,2 butanediol, 1,3 butanediol, 2-methyl-l,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 3-meethyl-l,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-l,3-pentanediol, 2-ethyl-l,3-hexanediol, 2-methyl-l,8-octanediol, 1,9-nonanediol, 1,10-decanediol and 1,12-octadecanediol. From the viewpoint of solubility of the synthesized ester, a branched alkylene glycol is preferred.

The alicyclic dibasic acid or its anhydride is an acid having an alicyclic structure and two ionizable hydrogen atoms in the molecule or an anhydride thereof.

Specific examples include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexane- dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,4-decahydronaphthalene- dicarboxylic acid, 1,5-decahydronaphthalenedicarboxylic acid, 2,6-decahydro- naphthalenedicarboxylic acid and 2,7-decahydronaphthalenedicarboxylic acid, and their acid anhydrides.

See further in US 2015/0141562 for details about the polyester binder systems.

Further binder components

The above-mentioned binder systems (e.g. the rosin binder, the non-aqueous dispersion binder system, the silylated acrylate binder system and the various hybrids) may have included therein - as a part of the binder system - one or more further binder components. It should be understood that the binder components mentioned below may alone also constitute the binder system, cf. the general presentation of the binder system.

Examples of such further binder components are: oils such as linseed oil and derivatives thereof, castor oil and derivatives thereof, soy bean oil and derivatives thereof; and other polymeric binder components such as saturated polyester resins; polyvinyl acetate, polyvinyl butyrate, polyvinyl chloride acetate, copolymers of vinyl acetate and vinyl isobutyl ether; vinyl chloride; copolymers of vinyl chloride and vinyl isobutyl ether; alkyd resins or modified alkyd resins;

hydrocarbon resins such as petroleum fraction condensates; chlorinated polyolefins such as chlorinated rubber, chlorinated polyethylene, chlorinated polypropylene; styrene copolymers such as styrene/butadiene copolymers, styrene/methacrylate and styrene/acrylate copolymers; acrylic resins such as homopolymers and copolymers of methyl methacrylate, ethyl methacrylate, n- butyl methacrylate, isobutyl methacrylate and isobutyl methacrylate; hydroxy- acrylate copolymers; polyamide resins such as polyamide based on dimerised fatty acids, such as dimerised tall oil fatty acids; cyclised rubbers; epoxy esters; epoxy urethanes; polyurethanes; epoxy polymers; hydroxy-polyether resins; polyamine resins; etc., as well as copolymers thereof.

Such further binder components typically constitutes 0-25 %, such as 5-20 %, by wet weight based on the coating composition.

The metal compound

The coating compositions of the present invention comprise a metal compound.

In principal, the metal compound may be any kind of compound which includes a metal ion.

The metal ion may be any metal ion with valency of 1, 2 or 3. Preferred metal ions include Cu(I) ions, Cu(II) ions, Zn ions, Co(II) ions, Ca ions, Mg ions and Fe(III) ions.

In most embodiments the metal compound is a metal compound, such as for example a metal oxide, a metal hydroxide or a metal salt, such as for example a metal chloride, a metal fluoride, a metal nitrate, a metal acetate, a metal sulphate, a metal hydrogensulphate, a metal phosphate, a metal

hydrogenphosphate and a metal dihydrogenphosphate.

In preferred embodiments the metal compound is selected from the group consisting of a metal oxide and a metal hydroxide and mixtures thereof.

In some embodiments the metal compound is a metal oxide. Suitable examples of metal ions which form part of the metal oxide include Cu(I) ions, Cu(II) ions, Zn ions, Co(II) ions, Ca ions, Mg ions and Fe(III) ions, thereby forming the oxides Cu₂0, CuO, ZnO, CoO, CaO, MgO and Fe₂0₃, respectively. Any mixtures of two or more oxides are also encompassed by the present invention. In a preferred embodiment the metal compound is a mixture of ZnO and Fe₂0₃. In another preferred embodiment, the metal compound is ZnO.

Typically, the amount of the metal compound is 1-50%, such as 1-30 %, for example 1-20 %, or 1-15 %, or 1-5 %, by solids volume of the coating composition. In other embodiments the amount of metal compound is 2-40%, such as 3-25%, for example 5-15% or 8-12% by solids volume of the coating composition. The alkoxysilane

The coating compositions of the present invention comprise one or more alkoxysilane(s). The alkoxysilane may be illustrated by the formula: SiR_n(OR)₄-n in which n = 0, 1, 2 or 3, and each of R is independently a Ci_₂o alkyl group in which R is optionally interrupted by an O group. Preferably, R is not interrupted by an O group.

It is preferred that the alkoxysilane has a relatively low molecular weight such as less than 400 g/mol.

Preferably, each R is independently a linear Ci-io or a branched C₃-i₀ alkyl group.

Most preferably each R is independently a Ci-₆ alkyl group, such as for example methyl, ethyl, n-propyl, iso-propyl or n-butyl.

Preferably n is 0, 1 or 2, i.e. the silane is a di- tri- or tetra-alkoxysilane. Most preferred n is 0, i.e. the silane is a tetraalkoxysilane.

Suitable alkoxysilanes are known to those in the art and many are available commercially. Examples of suitable alkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, methyltrimethoxysilane and trimethylethoxysilane. Preferred alkoxysilanes include tetraethoxysilane and tetrapropoxysilane. In most embodiments, the alkoxysilane constitutes 0.05-20%, such as 0.1-10%, preferably 0.2-5%, such as 0.3-2% by solids volume of the coating composition. In other embodiments, the alkoxysilane constitutes 0.05-2%, for example 0.08- 1.5%, such as 0.1-1% by solids volume of the coating composition.

Biocide

The coating compositions of the present invention may comprise one or more biocides.

In the present context, the term "biocide" is intended to mean an active substance intended to destroy, deter, render harmless, prevent the action of, or otherwise exert a controlling effect on any harmful organism by chemical or biological means.

Illustrative examples of non-metal biocides are those selected from heterocyclic nitrogen compounds such as 3a,4,7,7a-tetrahydro-2-((trichloromethyl)-thio)-lH- isoindole-l,3(2H)-dione, pyridine-triphenylborane, l-(2,4,6-trichlorophenyl)-lH- pyrrole-2,5-dione, 2,3,5,6-tetrachloro-4-(methylsulfonyl)-pyridine, 2-methylthio- 4-tert-butylamino-6-cyclopropylamine-s-triazin, and quinoline derivatives;

heterocyclic sulfur compounds such as 2-(4-thiazolyl)benzimidazole, 4,5-dichloro- 2-n-octyl-4-isothiazolin-3-one, 4,5-dichloro-2-octyl-3(2H)-isothiazoline (Sea- Nine^®-211N), l,2-benzisothiazolin-3-one, 2-(thiocyanatomethylthio)-benzo- thiazole, (RS 4-[l-(2,3-dimethylphenyl)ethyl]-3H-imidazole (Medetomidine, Selektope^®), and 4-Brom-2-(4-chlorphenyl)-5-(trifluormethyl)-lH-pyrrol-3- carbonitril (Tralopyril, Econea^®); urea derivatives such as N-(l,3- bis(hydroxymethyl)-2,5-dioxo-4-imidazolidinyl)-N,N'-bis(hydroxymethyl)urea, and N-(3,4-dichlorophenyl)-N,N-dimethylurea, Ν,Ν-dimethylchlorophenylurea; amides or imides of carboxylic acids; sulfonic acids and of sulfenic acids such as 2,4,6- trichlorophenyl maleimide, l,l-dichloro-N-((dimethylamino)sulfonyl)-l-fluoro-N- (4-methylphenyl)-methanesulfenamide, 2,2-dibromo-3-nitrilo-propionamide, N- (fluorodichloromethylthio)-phthalimide, N,N-dimethyl-N'-phenyl-N'- (fluorodichloromethylthio)-sulfamide, and N-methylol formamide; salts or esters of carboxylic acids such as 2-((3-iodo-2-propynyl)oxy)-ethanol phenylcarbamate and N,N-didecyl-N-methyl-poly(oxyethyl)ammonium propionate; amines such as dehydroabiethylamines and cocodimethylamine; substituted methane such as di(2-hydroxy-ethoxy)methane, 5,5'-dichloro-2,2'-dihydroxydiphenylmethane, and methylene-bisthiocyanate; substituted benzene such as 2,4,5,6-tetrachloro-l,3- benzenedicarbonitrile, l,l-dichloro-N-((dimethylamino)-sulfonyl)-l-fluoro-N- phenylmethanesulfenamide, and l-((diiodomethyl)sulfonyl)-4-methyl-benzene; tetraalkyl phosphonium halogenides such as tri-n-butyltetradecyl phosphonium chloride; guanidine derivatives such as n-dodecylguanidine hydrochloride;

disulfides such as bis-(dimethylthiocarbamoyl)-disulfide, tetramethylthiuram disulfide; imidazole containing compound, such as medetomidine; 2-(p- chlorophenyl)-3-cyano-4-bromo-5-trifluoromethyl pyrrole and mixtures thereof.

Currently preferred examples hereof are those selected from heterocyclic nitrogen compounds such as 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, 4,5-dichloro-2- octyl-3(2H)-isothiazoline (Sea-Nine^®-211N), (RS)-4-[l-(2,3- dimethylphenyl)ethyl]-3H-imidazole (Medetomidine, Selektope^®) and 4-Brom-2- (4-chlorphenyl)-5-(trifluormethyl)-lH-pyrrol-3-carbonitril (Tralopyril, Econea^®).

Illustrative examples of metal-containing biocides are those selected from metal- containing organic biocides like metallo-dithiocarbamates (such as bis(dimethyldi- thiocarbamato)zinc, zinc-ethylenebis(dithiocarbamate) (Zineb), ethylene-bis- (dithiocarbamato)manganese, dimethyl dithiocarbamate zinc, and complexes between these); bis(l-hydroxy-2(lH)-pyridinethionato-0,S)-copper (copper pyrithione); copper acrylate; bis(l-hydroxy-2(lH)-pyridinethionato-0,S)-zinc (zinc pyrithione); phenyl(bispyridyl)-bismuth dichloride; and metal-containing inorganic biocides like metal biocides such as copper(I)oxide, cuprous oxide, and metallic copper, copper metal alloys such as copper-nickel alloys like copper bronze; metal salts such as cuprous thiocyanate, basic copper carbonate, copper hydroxide, barium metaborate, copper chloride, silver chloride, silver nitrate and copper sulphide; and bis(N-cyclohexyl-diazenium dioxy) copper.

Currently preferred examples hereof are copper-containing biocides and zinc- containing biocides, in particular cuprous oxide, copper pyrithione, zinc pyrithione and zinc-ethylenebis(dithiocarbamate) (Zineb). Presently, it is preferred that the biocide, if present, does not comprise tin. Currently preferred biocides are those selected from the group consisting of 2,4,5,6-tetrachloroisophtalonitrile (Chlorothalonil), copper thiocyanate (cuprous sulfocyanate), N-dichlorofluoromethylthio-N',N'-dimethyl-N-phenylsulfamide (Dichlofluanid), 3-(3,4-dichlorophenyl)-l,l-dimethylurea (Diuron), N²-tert-butyl- N⁴-cyclopropyl-6-methylthio-l,3,5-triazine-2,4-diamine (Cybutryne), 4-bromo-2- (4-chlorophenyl)-5-(trifluoromethyl)-lH-pyrrole-3-carbonitrile, (2-(p- chlorophenyl)-3-cyano-4-bromo-5-trifluoromethyl pyrrole; Tralopyril), N²-tert- butyl-/V⁴-cyclopropyl-6-methylthio-l,3,5-triazine-2,4-diamine (Cybutryne), (RS)- 4-[l-(2,3-dimethylphenyl)ethyl]-3H-imidazole (Medetomidine), 4,5-dichloro-2-n- octyl-4-isothiazolin-3-one (DCOIT, Sea-Nine^® 211N), dichlor-N-((dimethyl- amino)sulfonyl)fluor-N-(p-tolyl)methansulfenamid (Tolylfluanid), 2- (thiocyanomethylthio)-l,3-benzothiazole ((2-benzothiazolylthio)methyl thiocyanate; TCMTB), triphenylborane pyridine (TPBP); bis(l-hydroxy-2(lH)- pyridinethionato-0,S)-(T-4) zinc (zinc pyridinethione; zinc pyrithione), bis(l- hydroxy-2(lH)-pyridinethionato-0,S)-T-4) copper (copper pyridinethione; copper pyrithione), zinc ethylene-l,2-bis-dithiocarbamate (zinc-ethylene-N-N'- dithiocarbamate; Zineb), copper(i) oxide, metallic copper, 3-(3,4-dichlorophenyl)- 1,1-dimethylurea (Diuron) and diiodomethyl-p-tolylsulfone; Amical 48. Preferably at least one biocide is selected from the above list.

In a particularly preferred embodiment, the biocides are preferably selected among biocides which are effective against soft fouling such as slime and algae. Examples of such biocides are N²-tert-butyl-N⁴-cyclopropyl-6-methylthio-l,3,5- triazine-2,4-diamine (Cybutryne), 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT, Sea-Nine^® 211N), bis(l-hydroxy-2(lH)-pyridinethionato-0,S)-(T-4) zinc (zinc pyridinethione; zinc pyrithione), bis(l-hydroxy-2(lH)-pyridinethionato-0,S)- T-4) copper (copper pyridinethione; copper pyrithione; Copper Omadine) and zinc ethylene- 1,2-bis-dithiocarbamate (zinc-ethylene-N-N'-dithiocarbamate; Zineb), copper(I) oxide, metallic copper, copper thiocyanate, (cuprous sulfocyanate), bis(l-hydroxy-2(lH)-pyridinethionato-0,S)-T-4) copper (copper pyridinethione; copper pyrithione; Copper Omadine).

In some embodiments, at least one biocide is an organic biocide. In a further particularly preferred embodiment, the one or more biocides are organic biocides, such as a pyrithione complex, such as zinc pyrithione, or such as copper pyrithione. Organic biocides are those either fully or in part being of organic origin.

In one important embodiment, the one or more biocides comprises at least one of bis(l-hydroxy-2(lH)-pyridinethionato-0,S)-(T-4) zinc (zinc pyridinethione; Zinc Pyrithione), bis(l-hydroxy-2(lH)-pyridinethionato-0,S)-(T-4) copper (copper pyridinethione; Copper Pyrithione) and zinc ethylene-l,2-bis-dithiocarbamate (zinc-ethylene-N-N'-dithiocarbamate; Zineb). As detailed in US 7,377,968, in those instances in which the biocide is depleted rapidly from the film due to e.g. a high water solubility or a high level of immiscibility with the binder matrix, it can be advantageous to add one or more of the biocide(s) in encapsulated form as a means of controlling the biocide dosage and extending the effective lifetime in the film. Encapsulated biocides can also be added if the free biocide alters the properties of the binder matrix in a way that is detrimental for its use as antifouling coatings (e.g. mechanical integrity, drying times, etc.).

In one embodiment, the biocide is encapsulated 4,5-dichloro-2-n-octyl-4- isothiazolin-3-one (Sea-Nine CR2).

The biocide preferably has a solubility in the range of 0-20 mg/L, such as

0.00001-20 mg/L, in water at 25 °C. In one particularly interesting embodiment, the biocide includes cuprous oxide. In this embodiment, the biocide is typically included in an amount of 3-65 %, such as 5-60 %, e.g. 10-60 %, or 15-60 %, or 15-40 %, or 20-60 %, by dry weight of the coating composition. Expressed as solids volume, the amount of the biocide is typically 3-45 %, such as 5-40 %, e.g. 7-38 %, or 10-35 %, or 15-35 %, by solids volume of the coating composition.

In another particularly interesting embodiment, the biocide only includes organic biocides. In this embodiment, the organic biocide(s) is/are typically included in a total amount of 0.25-30 %, such as 0.5-25 %, e.g. 0.75-20 %, or 1-15 %, or even 2-12 %, by dry weight of the coating composition. Expressed as solids volume, the amount of the organic biocide is typically 0.5-15 %, such as 1-12 %, e.g. 2-10 %, or 4-9 %, by solids volume of the coating composition.

Embodiments of the invention

In one embodiment, the present invention provides a self-polishing antifouling coating composition comprising:

a) 25-80% by solids volume of non-silicone-based binder matrix including a rosin- based binder system,

b) 1-50% by solids volume of a metal compound selected from the group consisting of a metal oxide and a metal hydroxide and mixtures thereof, and c) 0.1-10% by solids volume of one or more alkoxysilane(s).

In another embodiment, the present invention provides a self-polishing antifouling coating composition comprising:

a) 25-80% by solids volume of non-silicone-based binder matrix including a rosin- based binder system and an additional non-silicone-based binder system selected from the group consisting of non-aqueous dispersion binder systems, metal acrylate binder systems, hybrids of silylated acrylate and metal acrylate binder systems, polyoxalate binder systems, zwitterion binder systems, hybrids of silylated acrylate and zwitterion binder systems and polyester binder systems, b) 1-50% by solids volume of a metal compound selected from the group consisting of a metal oxide and a metal hydroxide and mixtures thereof, and c) 0.1-10% by solids volume of one or more alkoxysilane(s).

In yet another embodiment, the present invention provides a self-polishing antifouling coating composition comprising :

a) 25-80% by solids volume of non-silicone-based binder matrix including a rosin- based binder system and an additional non-silicone-based binder system selected from the group consisting of non-aqueous dispersion binder systems, metal acrylate binder systems, hybrids of silylated acrylate and metal acrylate binder systems, polyoxalate binder systems, zwitterion binder systems, hybrids of silylated acrylate and zwitterion binder systems and polyester binder systems, with the proviso that the binder matrix constitutes at most 10% of a silylated acrylate binder system, b) 1-50% by solids volume of a metal compound selected from the group consisting of a metal oxide and a metal hydroxide and mixtures thereof, and c) 0.1-10% by solids volume of one or more alkoxysilane(s). In a preferred embodiment, the present invention provides a self-polishing antifouling coating composition comprising :

a) 20-70% by solids volume of non-silicone-based binder matrix including a rosin- based binder system and an additional non-silicone-based binder system selected from the group consisting of non-aqueous dispersion binder systems, metal acrylate binder systems, hybrids of silylated acrylate and metal acrylate binder systems, polyoxalate binder systems, zwitterion binder systems, hybrids of silylated acrylate and zwitterion binder systems and polyester binder systems, with the proviso that the binder matrix constitutes at most 10% of a silylated acrylate binder system,

b) 1-20% by solids volume of a metal compound selected from the group consisting of a metal oxide and a metal hydroxide and mixtures thereof, and c) 0.3-2% by solids volume of one or more alkoxysilane(s).

In a more preferred embodiment, the present invention provides a self-polishing antifouling coating composition comprising :

b) 1-20% by solids volume of a metal compound selected from the group consisting of a metal oxide and a metal hydroxide and mixtures thereof, c) 0.3-2% by solids volume of one or more alkoxysilane(s), and

d) 3-45% by solids volume of biocide.

In an even more preferred embodiment, the present invention provides a self- polishing antifouling coating composition comprising: a) 50-55% by solids volume of non-silicone-based binder matrix including a rosin- based binder system and an additional non-silicone-based binder system selected from the group consisting of non-aqueous dispersion binder systems, metal acrylate binder systems, hybrids of silylated acrylate and metal acrylate binder systems, polyoxalate binder systems, zwitterion binder systems, hybrids of silylated acrylate and zwitterion binder systems and polyester binder systems, with the proviso that the binder matrix constitutes at most 10% of a silylated acrylate binder system,

b) 8-12% by solids volume of a metal compound selected from the group consisting of a metal oxide and a metal hydroxide and mixtures thereof, c) 0.1-1% by solids volume of one or more alkoxysilane(s), and

d) 15-35% by solids volume of biocide.

Application of the coating composition

The invention further relates to a marine structure having on at least a part of the surface thereof a coating prepared from the antifouling paint composition defined herein. The marine structure may be coated with one or several layers, in particular successive layers, of the coating composition.

The coating composition according to the invention may be applied to a marine structure to be protected in one or several successive layers, typically 1 to 4 layers, preferably 1 to 2 layers. The dry film thickness (DFT) of the coating applied per layer will typically be 10 to 600 μΐη, preferably 20 to 500 μΐη, such as 40 to 400 μΐη. Thus, the total dry film thickness of the coating will typically be 10 to 1,800 μΐη, preferably 20 to 1,500 μΐη, in particular 40 to 1,200 μΐη, such as 80 to 800 μΐη.

The marine structure to which the coating composition according to the invention may be applied to may be any of a wide variety of solid objects that come into contact with water, for example vessels, including but not limited to boats, yachts, motorboats, motor launches, ocean liners, tugboats, tankers, container ships and other cargo ships, submarines (both nuclear and conventional), and naval vessels (of all types) ; pipes; shore and off-shore machinery, constructions and objects of all types such as piers pilings, bridge substructures, floatation devices, underwater oil well structures etc.; nets and other mariculture installations; cooling plants; and buoys; and is especially applicable to the hulls of ships and boats and to pipes.

Prior to the application of a coating composition to a marine structure, the marine structure may first be coated with a primer-system which may comprise several layers and may be any of the conventional primer systems used in connection with application of coating compositions to marine structures. Thus the primer system may include an anti-corrosive primer optionally followed by a layer of an adhesion-promoting primer.

The above-mentioned primer system may, for example, be a combination of an epoxy resin having an epoxy equivalent of from 160 to 600 with its curing agent (such as an amino type, a carboxylic acid type or an acid anhydride type), a combination of a polyol resin with a polyisocyanate type curing agent, or a coating material containing a vinyl ester resin, an unsaturated polyester resin or the like, as a binder system, and, if required, further containing a thermoplastic resin (such as chlorinated rubber, an acrylic resin or a vinyl chloride resin), a curing accelerator, a rust preventive pigment, a colouring pigment, an extender pigment, a solvent, a trialkoxysilane compound, a plasticizer, an additive (such as antisagging agent or a precipitation preventive agent), or a tar epoxy resin type coating material, as a typical example.

In view hereof, the present invention also provides a method of coating a structure, comprising the steps of applying to at least a part of the structure thereof layer of an antifouling coating composition as defined herein. In some interesting embodiments, the layer is the final layer of a multi-layer coating system .

A coat

The present invention also provides a coat which is formed by applying one or more layer(s) of the coating composition of the invention to a surface of a structure, such as a marine structure. Subsequently, the applied coating composition is dried/cured and the coat is formed. The present inventors have surprisingly found that a coat produced as described above comprises a siloxane network which includes chemical structures, such as ≡Si-OH and≡Si-0-Si≡ in the dried/cured coat. It is believed that the presence of said structures may be important for obtaining the beneficial effects that are observed, i.e. the improved drying properties of the coating composition and the improved weathering properties of the coat.

In view of this finding, the present invention also relates to a coat as such, which is based on a non-silicone-based binder matrix and comprises a siloxane network including chemical structure such as≡Si-OH and≡Si-0-Si≡. In some embodiments the non-silicone-based binder matrix does not include any silylated acrylate binders.

EXAMPLES

Materials

Binders:

Chinese Gum Rosin ex. Arawaka Chemical Industries, (China), Gum Rosin Hypale CH ex. Arakawa Chemical Industries (China) Foral AX-E, ex Eastman Chemicals (Netherlands), Hydrogenated rosin

Acronal 9020 ex BASF (Germany), 60 wt.% solution in xylene, Acrylate co-binder Synocryl 7013-SD50 ex Archema (Spain), 50 wt.% solution in butanol/petroleum (1 : 2), Acrylic co-binder

NSP-100 ex Nitto Kasei, (Japan), 50 wt.% solution xylen/ethylbenzene (1 : 1), Silylated acrylic copolymer binder solution

Plasticizer; 45 wt.% solution in xylene,

Biocides:

Nordox Cuprous Oxide Paint Grade, ex Nordox, (Norway), cuprous oxide

Copper Omadine ex Arch Chemicals, (China), copper pyrithione

Zineb Nautec ex United Phosphorous, (India), zinc-ethylenebis(dithiocarbamate) DCOIT The Dow Chemical company, (USA), 4,5-dichloro-2-n-octyl-4-isothiazolin-3- one

Medetomidine, I-Tech Abv, (Sweden), Solvents:

Xylene

MIBK; methyl isobutyl ketone Additives:

Thickener:

Bentone 38 ex Elementis Specialties, (United Kingdom)

Wetting agents:

Nuosperse 657 RD ex Elementis Specialties (Netherlands)

Disperbyk 164 ex BYK Chemie, (Germany)

Anti-gelling agents:

DTBHQ ex Hangzhou Thomas (China), 2,5-diterbutyl hydroquinone

Thixotropic agents:

Aditix M 60 ex Supercolori (Italy), Modified polyethylene wax

Metal compounds acting as pigments and fillers:

Zinc Oxide Red Seal ex Umicore (Netherlands)

Iron oxide pigment; Micronox R01 ex Promindsa (Spain) Additional pigments and filler:

Casiflux F75 ex Ankerpoort (Netherlands), Natural calcium silicate

Alkoxysilane:

Dynasylan A EVONIK (Germany), Tetraethoxysilane (TEOS)

Tetrapropyl orthosilicate ex TCI Europe NV - division of TOKYO CHEMICAL INDUSTRY, Tetrapropoxysilane (TPOS)

Methods

Salt Spray Test (SST)

The Salt Spray Test was conducted according to ISO 9227. This method is performed in order to evaluate the corrosion resistance of a coating system by reproducing the corrosion that occurs in an atmosphere containing salt spray or splash. In this case, the test is used to reproduce the salty atmospheric conditions that surrounds the marine structures where the coating compositions are applied, and evaluating the formation of white precipitates on the surface of the coat. The operation conditions of the salt spray test were constant spray with 5% NaCI solution at 35°C.The test panels are placed in racks at an angle ofbetweenl5° and 25° to the vertical. After ending of the exposure (168 hours), the formation of white precipitates was visually evaluated.

In order to quantify the improvement in whitening resistance the gloss of the film was evaluated before and after being exposed in SST. The retention of gloss was measured with a micro-TRI gloss from BYK Gardner Gmbh with the Cat-No: 4430 and the Serial No: 1001994. The measurement took place at 85 degrees on the surface of the panels before and after exposure to SST. For each panel 3 measurements were taken and the average was calculated. To evaluate the paints the difference between the value before SST and after exposure to SST was plotted against the content of TEOS in the paint. Determination of Drying time (Beck Koller)

The test method is used for determining the Beck Koller drying time following ASTM D 5895-03. The paint was applied upon a glass strip by means of the applicator, using the 400 micron clearance. The test strip was immediately placed on the drying time recorder between the brass studs. A needle carrier was used to drawn along the film. The records define stages known from the finger method: (I) set-to-touch, (II) tack free, (III) dry-hard and (IV) Dry- through. In this test, the time required to reach the stage III (dry-hard) was evaluated.

Wood Block Setting Test

The drying and hardness of the film was evaluated. For this purpose, an acrylic panel (200x100x5.0 mm) was coated with the 400 μιη (DFT) with a Doctor Blade type applicator and let it drying at 5°C for 6 days. The measurement was done after 1 day, 2 days, 3 days and 6 days by placing a square plastic piece (30x30 mm) on the film and applying pressure (40Kg/Cm²) with the vise clamp apparatus for 1 minute. The condition of the mark left on the film will assess the drying and hardness of the film according to the evaluation described below: Performance Description

Excellent No significant deformation is observed

Good Heap is observed

Fair Large heap is observed

Poor Very or large heap is observed

Cosmetic property test: Atmospheric Exposure in Sea Conditions

An acrylic test panel (15 x 20 cm2), sandblasted on one side to facilitate adhesion of the coating, is first coated with 80 μιη (DFT) of a commercial vinyl tar primer (Hempanyl 16280 ex Hempel's Marine Paints A/S) applied by air spraying. After a minimum drying time of 24 hours in the laboratory at room temperature the test paint is applied with a Doctor Blade type applicator, with four gap sizes with a film width of 80 mm. One coat was applied in a DFT of 90-100 μιη. After at least 72 hours drying the test panels are fixed on a rack and exposed in sea conditions.

Test at Vilanova i la Geltru in Northeastern Spain

Every 4 weeks, inspection of the panels is made and the whitening is evaluated. Test at Busan, Korea

Every 4 weeks, inspection of the panels is made and the whitening is evaluated. Polishing rate test

Polishing and leaching characteristics are measured using a rotary set-up similar to the one described by Kiil et al. (Kiil, S, Weinell, C E, Yebra, D M, Dam- Johansen, K, "Marine biofouling protection: design of controlled release antifouling paints." In: Ng, K M, Gani, R, Dam-Johansen, K (eds.) Chemical Product Design;

Towards a Perspective Through Case Studies, 23IDBN-13: 978-0-444-52217-7.

Part II (7), Elsevier (2006)). The set-up consists of a rotary rig, which has two concentric cylinders with the inner cylinder (rotor, diameter of 0.3 m and height 0.17 m) capable of rotation. The cylinder pair is immersed in a tank containing about 400-500 litres of Artificial Seawater (cf. Table below).

The tank is fitted with baffles to break the liquid flow, which enhances turbulence and enables faster mixing of the species released from the paints and enhance heat transfer from a thermostating system. The purpose of using two cylinders is to create a close approximation to couette flow (flow between two parallel walls, where one wall moves at a constant velocity). The rotor is operated at 20 knots at 25 °C (unless otherwise specified), and the pH is adjusted frequently to 8.2 using 1 M sodium hydroxide or 1 M hydrochloric acid. Samples are prepared using overhead transparencies (3M PP2410) that are primed using two-component paint (Hempadur 47182 ex Hempel) applied using a Doctor Blade applicator with a gap size of 200 μιη. Coating samples are applied adjacent to each other using a Doctor Blade applicator with a gap of 250 μιη. After drying for 1 day, the coated transparency is cut in strips of 2 cm resulting in eight samples of 1.5 x 2 cm² on a long (21 cm) strip. The strips are mounted on the rotor, and left to dry for a week.

After one week, the test is initiated, and during the experiment, samples are removed after 35, 65 and 140 days in order to inspect the polishing and leaching depths. The samples are dried for three days at ambient conditions, after which they are cut in half and cast in paraffin. The internal front of the sample is planed off before total film thickness and leached layer thickness is established using light microscopy (coating cross-section inspection). Example 1: Testing the amount of alkoxysilane in a non-aqueous dispersion binder system:

Model paints based on a non-aqueous dispersion binder system without an alkoxysilane (example la) and a non-aqueous dispersion binder system with an alkoxysilane (TEOS) (example lb) is tested using the salt spray test (SST) as described above, for 1 week.

The results are shown in table 1 below and in Figure 1. All ratios are in solids volume. Table 1

Further, the gloss difference was measured before and after exposing the panels in SST during 1 week. This result is shown in Figure 2. Example 1 shows the effect of the addition of an alkoxysilane, TEOS, already at 0.1 vol-%. The whitening is gradually reduced, and at levels above 0.5 vol-% there is no whitening. The gloss difference is reduced linearly as a function of the TEOS concentration.

Example 2: Testing of an alkoxysilane in different binder systems: Model paints based on three different binder systems is tested using the salt spray test (SST) as described above, for 1 week.

Example 2al uses a rosin-based binder system without an alkoxysilane and example 2a2 includes an alkoxysilane (TEOS).

Example 2bl uses a non-aqueous dispersion binder system without an

alkoxysilane and example 2b2 includes an alkoxysilane (TEOS).

Example 2cl uses a rosin-based binder system without an alkoxysilane and example 2c2 includes an alkoxysilane (TEOS).

Results are shown in the tables 2a, 2b and 2c below and in Figure 3. All ratios are in solids volume.

Table 2a

Table 2b

Table 2c

The addition of an alkoxysilane improves gloss retention after salt spray exposure for 1 week in all three binder systems. This is shown in Figure 4. In all three binder systems, the whitening is prominent without the use of an alkoxysilane. When alkoxysilane is present, there is little or no whitening. Further the gloss difference is markedly reduced in all three binder systems, when an alkoxysilane is present.

Example 3: Long term testing in sea conditions

Model paints based on a non-aqueous dispersion binder system with an alkoxysilane, using 3 wt-% TEOS (example 3a) and 1.5 wt-% TEOS (example 3b), is tested using the cosmetic property test as described above to see how the whitening is affected in sea conditions after several months of exposure. The model paint of example la is used as a reference. Formula examples

The results are shown in table 3 and in Figure 5 the results after 7 months in sea conditions at Vilanova, Spain, is shown and in Figure 6 the results after 2 months in sea conditions in Korea.

Table 3

Example 3 shows that there is no whitening even after several months of exposure at sea conditions. These results can be compared with the results of example 1, where the same model paint is used and tested is SST. Example 4: Improvement of the drying time in a non-aqueous dispersion binder system by the addition of an alkoxysilane.

Improvement of the drying properties in a non-aqueous dispersion binder by the inclusion of an alkoxysilane was corroborated using a different drying test as described above (Beck Koller and Wood Block Setting Test)

The results obtained in the Beck Koller, stage III (BKIII) test showed that, as the content increased from 0 to 0.1% by volume of TEOS, the drying time did not change significantly. However, by adding 0.2 to 0.75 vol% TEOS, the drying time decreases steadily and remains at a plateau <0.75 vol% TEOS. When comparing BKIII of the paint without and with 0.75% by volume of TEOS in the formula, the drying time decreases from 4 hours to 45 minutes, respectively.

Figure 8 shows the drying properties of the paint with and without TEOS at 5 °C. Bearing in mind that the larger the heap left in the paint after applying pressure, slower the drying, it can be observed that there is a noticeable improvement in the drying properties of the paint containing TEOS. As shown, paint containing TEOS only needs 3 days to dry, while the drying of the paint without TEOS takes longer than 6 days. The results are shown in Figure 7 (Beck Koller test) and Figure 8 (Wood Block Setting test).

Example 5: Influence of an alkoxysilane and/or a divalent metal oxide in silyl acrylate paints Example 5 is conducted to test the whitening in paints comprising a silylated acrylate binder. Different silylated paints were prepared containing different combinations of an alkoxysilane and a divalent metal oxide (see Table 4) : one with ZnO and TEOS, one with ZnO but without TEOS, one without ZnO but with TEOS, and one without both ZnO and TEOS. The four paints were coated onto acrylic test panels (DFT 150 microns) and subjected to the salt spray test as described above. The results are shown in Table 4 and Figure 9. In all four paints, no whitening occurred after 1 week of exposure indicating that the principal role of an alkoxysilane in antifouling paints based on silyl acrylate is as water scavenger to stabilize the silyl acrylate binder.

Table 4

Table 4 (continued)

Example 6: Testing the amount of alkoxysilane in a non-aqueous dispersion binder system:

Model paints based on a non-aqueous dispersion binder system without an alkoxysilane (example 6a) and a non-aqueous dispersion binder system with an alkoxysilane (TPOS) (example 6b) is tested using the salt spray test (SST) as described above, for 1 week.

The results are shown in table 5 below and in Figure 10. All ratios are in solids volume. Table 5

Further, the gloss difference was measured before and after exposing the panels in SST during 1 week. This result is shown in Figure 11. Example 6 shows the effect of the addition of an alkoxysilane, TPOS, already at 0.5 vol-%. The whitening is reduced, and at levels above 0.5 vol-% the resistance against whitening is improved. Figure 12 shows the improvement in drying time by adding an alkoxysilane to a non-aqueous binder system. The drying time is reduced by the same level, with both TEOS and TPOS.

Claims

1. A self-polishing antifouling coating composition comprising :

a) a non-silicone-based binder matrix including a rosin-based binder system, b) a metal compound selected from the group consisting of a metal oxide and a metal hydroxide and mixtures thereof, and

c) one or more alkoxysilane(s).

2. The coating composition according to claim 1, wherein the non-silicone-based binder matrix includes an additional non-silicone-based binder system selected from the group consisting of non-aqueous dispersion binder systems, metal acrylate binder systems, hybrids of silylated acrylate and metal acrylate binder systems, polyoxalate binder systems, zwitterion binder systems, hybrids of silylated acrylate and zwitterion binder systems and polyester binder systems.

3. The coating composition according to any one of the preceding claims, wherein the rosin-based binder system comprises one or more rosin constituent(s) selected from the group consisting of rosin, rosin derivatives and rosin-modified polymers.

4. The coating composition according to any one of the preceding claims, wherein the metal oxide is selected from the group consisting of Cu₂0, CuO, ZnO, CoO, CaO, MgO and Fe₂0₃.

5. The coating composition according to any one of the preceding claims, wherein the one or more alkoxysilane(s) is selected from the group consisting of tetraethoxysilane and tetrapropoxysilane.

6. The coating composition according to any one of the preceding claims, wherein the binder matrix constitutes 25-80% by solids volume of the coating

composition.

7. The coating composition according to any one of the preceding claims, wherein the metal compound constitutes 1-50% by solids volume of the coating composition.

8. The coating composition according to any one of the preceding claims, wherein alkoxysilane constitutes 0.1-10% by solids volume of the coating composition.

9. The coating composition according to any one of the preceding claims, wherein said coating composition further comprises one or more biocide(s).

10. The coating composition according to claim 9, wherein the one or more biocide(s) constitutes 3-45% by solids volume of the coating composition.

11. The coating composition according to any one of the preceding claims, wherein the ratio between alkoxysilane and rosin is 1-300 in solids volume.

12. A method of coating a marine structure comprising the step of applying to at least a part of said marine structure a layer of a coating composition as defined in any one of claims 1-11.

13. A marine structure coated with one or several layers of a coating composition as defined in any one of the claims 1-11.

14. The marine structure according to claim 13, wherein the coat comprises a siloxane network including one or more chemical structures selected from the group consisting of≡Si-OH and≡Si-0-Si≡.

15. A coat on a marine structure coated with one or several layers of a coating composition as defined in any one of the claims 1-11, wherein said coat comprises a siloxane network including one or more chemical structures selected from the group consisting of≡Si-OH and≡Si-0-Si≡.