Composition

INTRODUCTION

The present invention relates to an antifouling coating composition comprising an acrylic acetal ester copolymer and a zinc salt of a monocarboxylic acid. The invention also relates to an antifouling coating composition comprising an acrylic acetal ester copolymer, a monocarboxylic acid and a zinc compound that reacts with the monocarboxylic acid to form a zinc salt of a monocarboxylic acid. The invention also relates to methods of preparing the compositions as well as to paints comprising the compositions, to a paint container containing the compositions and to kits for preparing the paints. Additionally the invention relates to an article comprising a coating on at least a part of a surface thereof and to a method of coating an article to prevent fouling thereon comprising coating at least a part of a surface of the article with the composition.

BACKGROUND

Surfaces that are submerged in seawater are subjected to fouling by marine organisms such as green and brown algae, barnacles, mussels and tube worms. On marine constructions such as vessels (e.g. ships, tankers), oil platforms and buoys such fouling is undesired and has economic consequences. The fouling may lead to biological degradation of the surface, increased load and accelerated corrosion. On vessels the fouling increases the frictional resistance which will cause reduced speed and/or increased fuel consumption.

To prevent settlement and growth of marine organisms antifouling paints are used. Some of the most successful paints currently on the market are self-polishing antifouling paints based on hydrolysable acrylic polymers as binders. There are two main self-polishing technologies - silyl acrylate copolymers and metal acrylate copolymers, of which the silyl acrylate copolymers are the most successful. When these copolymers are present in antifouling coating compositions along with an antifouling agent, the composition yields coatings that dry efficiently to yield antifouling coatings or films with a desirable level of hardness. The coatings also exhibit a constant degradation rate once in contact with sea water resulting in controlled release of the antifouling agent from the coating over time. Sometimes the controlled release is referred to as a controlled polishing rate over time. A third class of copolymers that have been developed as a hydrolysable binder are (meth)acrylic acetal ester copolymers. These copolymers are attractive in that they are cheaper and made from more sustainable monomers than the silyl ester copolymers. A significant difficulty encountered with the use of (meth)acrylic acetal ester copolymers in self-polishing antifouling coating compositions and coatings, however, is that they tend to bulk hydrolyse. This manifests in a slow and controlled initial polishing rate, followed by loss of the integrity of the coating and its disintegration over a relatively short period of time. This hugely limits the commercial use of this class of self-polishing paints as antifouling paints are required to last from 1 to 10 years depending on the application.

The challenge faced by the paint industry is to produce antifouling coating compositions and paints which dry efficiently to produce adequate hardness of the coatings or films. It is also highly desirable for the coating or film to exhibit a controlled degradation rate once in contact with sea water over a prolonged period of time, e.g. up to 5 years. Clearly it is also important that the composition and paint can be applied by standard techniques such as airless spraying, which in turn means compositions and paints having a certain viscosity level, whilst minimising their VOC content and still achieving good application properties.

SUMMARY OF THE INVENTION

Viewed from a first aspect the present invention provides an antifouling coating composition comprising:

(i) an acrylic acetal ester copolymer; and

(ii) a zinc salt of a monocarboxylic acid.

Viewed from a further aspect the present invention provides an antifouling coating composition comprising:

(i) an acrylic acetal ester copolymer;

(ii) a monocarboxylic acid; and

(iii) a zinc compound that reacts with the monocarboxylic acid to form a zinc salt of the monocarboxylic acid.

Viewed from a further aspect the present invention provides a method for preparing a composition as hereinbefore defined comprising mixing:

(i) an acrylic acetal ester copolymer; and

(ii) a zinc salt of a monocarboxylic acid. Viewed from a further aspect the present invention provides a method for preparing a composition as hereinbefore defined comprising mixing:

(i) an acrylic acetal ester copolymer;

(ii) a monocarboxylic acid; and

(iii) a zinc compound that reacts with the monocarboxylic acid to form a zinc salt of the monocarboxylic acid.

Viewed from a further aspect the present invention provides a paint comprising a composition as hereinbefore described.

Viewed from a further aspect the present invention provides a paint container containing a composition as hereinbefore described.

Viewed from a further aspect the present invention provides a kit for preparing a paint as hereinbefore described comprising:

(i) a first container containing an acrylic acetal ester copolymer and optionally a stabilizer and/or a dehydrating agent;

(iii) a second container containing a zinc salt of a monocarboxylic acid and optionally a dehydrating agent; and

(iv) optionally instructions for mixing the contents of said first and second containers.

Viewed from a further aspect the present invention provides a kit for preparing a paint as hereinbefore described comprising:

(i) a first container containing an acrylic acetal ester copolymer and optionally a stabilizer and/or a dehydrating agent;

(ii) a second container containing a monocarboxylic acid, a zinc compound that reacts with the monocarboxylic acid to form a zinc salt of the monocarboxylic acid and optionally a dehydrating agent; and

(iii) optionally instructions for mixing the contents of said first and second containers.

Viewed from a further aspect the present invention provides an article comprising (e.g. covered with or coated with) a coating on at least a part of a surface thereof, wherein said coating comprises the composition as hereinbefore described.

Viewed from a further aspect the present invention provides a method of coating an article to prevent fouling thereon, wherein said method comprises:

coating at least a part of a surface of said article with a composition as hereinbefore described; and drying and/or curing said coating.

Viewed from a further aspect the present invention provides the use of a composition as hereinbefore described for coating at least a part of a surface of an article to prevent fouling thereon.

DEFINITIONS

As used herein the term “antifouling coating composition” refers to a composition that, when applied to a surface, prevents or minimises growth of marine organisms on a surface.

As used herein the term “paint” refers to a composition comprising the antifouling coating composition as herein described and optionally solvent which is ready for use, e.g. for spraying. Thus the antifouling coating composition may itself be a paint or the antifouling coating composition may be a concentrate to which solvent is added to produce a paint.

As used herein the term“acrylic acetal ester copolymer” refers to a polymer comprising repeat units derived from hemiacetal and hemiketal esters of (meth)acrylic acid. The repeat units comprise the group -(CO)-OCR’R’O- wherein R’ is H or alkyl and R” is alkyl. Thus the term covers polymers comprising repeat units derived from methacrylate acetal ester monomers and acrylate acetal ester monomers. As used herein, the term“acetal ester” encompasses both esters of hemiacetals and esters of hemiketals.

The term“acrylic polymer” refers to polymers and copolymers based on acrylic acid, methacrylic acid, esters of acrylic acid, esters of methacrylic acid and, in the case of copolymers, mixtures thereof.

As used herein the term "(meth)acrylate" refers to either acrylate or methacrylate; and the term "(meth)acrylic" refers to either acrylic or methacrylic.

As used herein the term“alkyl” refers to saturated, straight chained, branched or cyclic groups. Alkyl groups may be substituted or unsubstituted.

As used herein the term“cycloalkyl” refers to a saturated or partially saturated mono- or bicyclic alkyl ring system containing 3 to 10 carbon atoms. Cycloalkyl groups may be substituted or unsubstituted.

As used herein the term“alkylene” refers to a divalent alkyl group.

As used herein the term “aryl” refers to a group comprising at least one aromatic ring. The term aryl encompasses heteroaryl as well as fused ring systems wherein one or more aromatic ring is fused to a cycloalkyl ring. Aryl groups may be substituted or unsubstituted. An example of an aryl group is phenyl, i.e. C ₆ H ₅ . Phenyl groups may be substituted or unsubstituted.

As used herein the term "heterocyclyl" refers to a saturated (e.g. heterocycloalkyl) or unsaturated (e.g. heteroaryl) heterocyclic ring moiety having 3, 4, 5, 6, 7, 8, 9 or 10 ring atoms, at least one of which is selected from nitrogen, oxygen and sulfur.

As used herein the term "substituted" refers to a group wherein one or more, for example up to 6, more especially 1 , 2, 3, 4, 5 or 6, of the hydrogen atoms in the group are replaced independently of each other by the corresponding number of the described substituents. The term "optionally substituted" as used herein means substituted or unsubstituted.

As used herein the term “monocarboxylic acid” refers to a compound comprising one -COOH group.

As used herein the term“resin acid” refers to a mixture of carboxylic acids present in resins.

As used herein the term“rosin” refers to rosin and rosin derivatives.

As used herein the term “reactive zinc compound” refers to zinc-containing compounds which react with monocarboxylic acid to produce a zinc salt of monocarboxylic acid. The reaction may take place during paint production, during storage or during mixing prior to use.

As used herein the term“zinc salt of a monocarboxylic acid” refers to a zinc carboxylate. Zinc salts of monocarboxylic acids comprise at least one, and preferably two, carboxylate (-COO ) group which is bound or complexed with a zinc cation, Zn ²⁺ .

As used herein the term “stabiliser” refers to acid scavengers. Stabilisers contribute to the storage stability of the compositions of the invention.

As used herein the term“carbodiimide” refers to a compound comprising the functional group -N=C=N-.

As used herein the term“dehydrating agent” refers to a water scavenger or drying agent, which removes water from the compositions.

As used herein “antifouling agent” refers to a compound or mixture of compounds that prevents the settlement of marine organisms on a surface, and/or prevents the growth of marine organisms on a surface and/or encourages the dislodgement of marine organisms from a surface. As used herein the term“extender” is used interchangeably with“filler” and refers to a compound which increases the volume or bulk of a coating composition.

As used herein the term“molecular weight” refers to weight average molecular weight (Mw), unless otherwise specified.

As used herein the term“PDI” or polydispersity index refers to the ratio Mw/Mn, wherein Mn refers to number average molecular weight.

As used herein the term “volatile organic compound (VOC)” refers to a compound having a boiling point equal to or below 250°C at an atmospheric pressure of 101.3 kPa.

As used herein the term“wt% based on the total weight of the composition” refers to the wt% of a component present in the final, ready to use, composition, unless otherwise specified.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an antifouling coating composition comprising:

(i) an acrylic acetal ester copolymer; and

(ii) a zinc salt of a monocarboxylic acid;

or

(i) an acrylic acetal ester copolymer;

(ii) a monocarboxylic acid; and

(iii) a zinc compound that reacts with the monocarboxylic acid to form a zinc salt of a monocarboxylic acid;

Optionally the compositions further comprise one or more of: (iv) an antifouling agent; (v) a pigment and/or extender; (vi) a cobinder; (vii) a solvent; (viii) a stabiliser compound; (ix) a dehydrating agent and/or (x) an additive.

In the antifouling coating compositions of the present invention the combination of an acrylic acetal ester copolymer with a zinc salt of a monocarboxylic acid advantageously provides a composition which dries relatively quickly to form a hard coating or film. The zinc salt of monocarboxylic acid may be present in the initial composition or it may be formed in situ from a monocarboxylic acid and a zinc compound that reacts with the monocarboxylic acid to form a zinc salt of a monocarboxylic acid. The coatings formed from the compositions of the invention also polish at a controlled, e.g. substantially linear, degradation rate over an extended period of time, e.g. 1-10 years. This, in turn, means that the coatings provide controlled release of antifouling agents over an extended period of time, e.g. 1 -10 years.

Acrylic acetal ester copolymer

The acrylic acetal ester polymer present in the antifouling coating composition of the present invention is a copolymer. Preferably the acrylic acetal ester copolymer comprises at least two (e.g. 2, 3, or 4) different monomers and more preferably two or three different monomers. The different monomers may be different (meth)acrylic acetal ester monomers or a single type of (meth)acrylic acetal ester monomer and another type of monomer, e.g. a (meth)acrylic acid ester monomer. Particularly preferred acrylic acetal ester copolymers present in the antifouling coating composition of the present invention comprise at least one (meth)acrylic acetal ester monomer and at least one (meth)acrylic acid ester monomer.

Preferred acrylic acetal ester copolymer present in the antifouling coating composition of the present invention comprises a residue of at least one monomer of formula (I):

wherein

R ¹ is H or methyl;

R ² is H or Ci alkyl, preferably H;

R ³ is Ci alkyl; and

R ⁴ is optionally substituted, linear or branched, Ci _-2 o alkyl, C _5-i o cycloalkyl or C _6-i o aryl; or

R ³ and R ⁴ , together with the O atom to which they are attached, form an optionally substituted C _4-8 membered ring.

In monomers of formula (I), when R ² is Ci _-4 alkyl, it is preferably Ci _-3 alkyl, and more preferably Ci _-2 alkyl. Yet more preferably when R ² is Ci _-4 alkyl, R ² is selected from methyl, ethyl, n-propyl and / ^' -propyl. In preferred monomers of formula (I), R ² is methyl or H and particularly preferably H.

In some preferred monomers of formula (I), R ³ is Ci _-4 alkyl, more preferably Ci _-3 alkyl, and still more preferably Ci _-2 alkyl. Yet more preferably R ³ is selected from methyl, ethyl, n-propyl and / ^' -propyl and still more preferably from methyl and ethyl. In preferred monomers of formula (I), R ³ is methyl.

In some preferred monomers of formula (I), R ² is H and R ³ is methyl or ethyl, especially methyl.

In further preferred monomers of formula (I), R ⁴ is unsubstituted C2-20 alkyl When R ⁴ is unsubstituted C _2-20 alkyl, the alkyl group preferably comprises 2 to 18 carbon atoms, more preferably 4 to 12 carbon atoms, e.g. 4, 5 or 6 carbon atoms. Preferred alkyl groups comprise 4 to 8 carbon atoms. Alkyl groups may be straight chained or branched. When R ⁴ is unsubstituted C _2-20 alkyl, the alkyl group is preferably selected from butyl, pentyl, hexyl, heptyl, octyl, dodecyl and octadecyl. When R ⁴ is butyl, it is preferably n-butyl or isobutyl. When R ⁴ is octyl, it is preferably 2-ethylhexyl.

In further preferred monomers of formula (I), R ⁴ is substituted Ci _-20 alkyl. When R ⁴ is substituted Ci _-20 alkyl, the alkyl group preferably comprises 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, e.g. 1 , 2, 3, 4, or 6 carbon atoms. The alkyl group is preferred straight chained. Preferably the alkyl group is selected from methyl, ethyl, n-propyl, n-butyl, pentyl, hexyl, heptyl and octyl. When R ⁴ is substituted Ci _-20 alkyl, the substituent may be halogen, C _5-i o cycloalkyl, C _6-i o aryl, heterocyclyl or OR ⁵ wherein R ⁵ is selected from H, Ci _-8 alkyl, C _3-8 cycloalkyl and (CH ₂ CH _(2-m) (CH ₃ ) _m O) _n R ⁶ wherein R ⁶ is selected from H, Ci _-4 alkyl and phenyl, m is 0 or 1 and n is an integer from 1 to 20, preferably 1 to 6. Optionally the C _5-i0 cycloalkyl substituent is itself substituted by an OH group. More preferably the substituent is aryl (e.g. phenyl), heterocyclyl or OR ⁵ wherein R ⁵ is selected from H, Ci _-8 alkyl and (CH ₂ CH ₂ 0) _n R ⁶ wherein R ⁶ is H or Ci- alkyl and n is an integer from 1 to 20, preferably 1 to 6.

When the alkyl group is substituted by a heterocyclyl, the heterocyclyl is preferably a 3- to 10-membered ring or ring system and more particularly a 5- or 6- membered ring, which may be saturated or unsaturated. Preferably the heterocyclyl is saturated. A representative example of a heterocyclyl group that may be present is tetra hydrofury I or tetrahydropyranyl.

When the alkyl group is substituted by OR ⁵ , R ⁵ is preferably selected from H, Ci _-8 alkyl (e.g. Ci _-3 alkyl) and (CH ₂ CH _(2-m) (CH ₃ ) _m O) _n R ⁶ wherein R ⁶ is H, Ci _-4 alkyl or phenyl, m is 0 or 1 and n is an integer from 1 to 20, preferably 1 to 6. Representative examples of R ⁵ include H, methyl, ethyl, (CH ₂ CH ₂ 0)CH ₃ and (CH ₂ CH ₂ 0)CH ₂ CH ₃ .

In further preferred monomers of formula (I), R ⁴ is unsubstituted C _5-i0 cycloalkyl. Preferred cyclic alkyl groups comprise 6 to 8 carbon atoms. Cycloalkyl groups may be a bridged or polycyclic ring system. Preferred cycloalkyl groups are monocyclic. When R ⁴ is unsubstituted C _5-i o cycloalkyl, the cycloalkyl group is preferably cyclohexyl.

In further preferred monomers of formula (I), R ⁴ is substituted C _5-i0 cycloalkyl. When R ⁴ is substituted C _5-i o cycloalkyl, the alkyl group preferably comprises 6 to 8 carbon atoms, e.g. 6 carbon atoms. The cycloalkyl group is preferably cyclohexyl. When R ⁴ is substituted C _5-i0 cycloalkyl, the substituent may be Ci _-4 alkyl or OR ⁵ wherein R ⁵ is selected from H or Ci _-8 alkyl. More preferably the substituent is Ci _-4 alkyl or OR ⁵ wherein R ⁵ is selected from H and Ci _-8 alkyl.

When the cycloalkyl group is substituted by OR ⁵ , R ⁵ is preferably selected from H and Ci _-8 alkyl (e.g. Ci _-3 alkyl). Representative examples of R ⁵ include H, methyl and ethyl.

In further preferred monomers of formula (I), R ⁴ is unsubstituted C _6-i o aryl. When R ⁴ is unsubstituted C _6-i o aryl, the aryl group preferably comprises 6 or 10 carbon atoms. Preferred aryl groups include phenyl.

In further preferred monomers of formula (I), R ⁴ is substituted C _6-i o aryl. When R ⁴ is substituted C _6-i o aryl, the aryl group preferably comprises 6 or 10 carbon atoms. Preferred aryl groups include phenyl. The substituent is preferably selected from halogens, Ci _-8 alkyl and OR ⁵ wherein R ⁵ is selected from H and Ci _-8 alkyl.

In still further preferred monomers of formula (I), R ⁴ is optionally substituted, linear or branched, C _-i8 alkyl or C _5-i0 cycloalkyl. Still more preferably R ⁴ is unsubstituted C _4-i8 alkyl or unsubstituted C _5-i o cycloalkyl. Yet more preferably R ⁴ is selected from butyl, pentyl, hexyl, heptyl, octyl, dodecyl, octadecyl and cyclohexyl and particularly preferably from butyl, octyl, dodecyl, octadecyl and cyclohexyl. When R ⁴ is butyl, it is preferably n-butyl or isobutyl. When R ⁴ is octyl, it is preferably 2-ethylhexyl.

In some preferred monomers of formula (I), R ² is H, R ³ is methyl or ethyl, especially methyl and R ⁴ is selected from butyl, pentyl, hexyl, heptyl, octyl, dodecyl, octadecyl and cyclohexyl. When R ⁴ is butyl, it is preferably n-butyl or isobutyl. When R ⁴ is octyl, it is preferably 2-ethylhexyl.

In other preferred monomers of formula (I), R ³ and R ⁴ , together with the O atom to which they are attached, form an optionally substituted C _-8 membered ring. When R ³ and R ⁴ , together with the O atom to which they are attached, form an unsubstituted C _4-8 membered ring, the ring preferably comprises 4 or 5 carbon atoms, i.e. together with the O atom, a 5 or 6 membered ring is formed. Preferably R ³ and R ⁴ , together with the O atom to which they are attached, form an unsubstituted tetrahydrofuranyl or tetrahydropyranyl ring. When R ³ and R ⁴ , together with the O atom to which they are attached, form a substituted C _4-8 membered ring, the ring preferably comprises 4 or 5 carbon atoms, i.e. together with the O atom, a 5 or 6 membered ring is formed. Preferably R ³ and R ⁴ , together with the O atom to which they are attached, form a substituted tetrahydrofuranyl or tetrahydropyranyl ring. The substituent(s) is preferably selected from halogens, Ci _-8 alkyl and OR ⁵ wherein R ⁵ is selected from H or Ci _-8 alkyl.

In some preferred monomers of formula (I), R ² is H, and R ³ and R ⁴ , together with the O atom to which they are attached, form an unsubstituted tetrahydrofuranyl or tetrahydropyranyl ring.

Preferred monomers present in the antifouling coating composition of the present invention include 1 -n-butoxyethyl methacrylate, 1-isobutoxyethyl methacrylate, 1-(2-ethylhexyloxy)ethyl methacrylate, 1-cyclohexyloxyethyl methacrylate, 1- dodecyloxyethyl methacrylate, 1-octadecyloxyethyl methacrylate, 2-tetrahydrofuranyl methacrylate, 2-tetrahydropyranyl methacrylate, 1 -n-butoxyethyl acrylate, 1- isobutoxyethyl acrylate, 1-(2-ethylhexyloxy)ethyl acrylate, 1-cyclohexyloxyethyl acrylate, 1-dodecyloxyethyl acrylate, 1-octadecyloxyethyl acrylate, 2-tetrahydrofuranyl acrylate and 2-tetrahydropyranyl acrylate. 1-isobutoxyethyl methacrylate, 1- cyclohexyloxyethyl methacrylate, and 2-tetrahydropyranyl methacrylate are particularly preferred monomers.

Preferably the acrylic acetal ester copolymer present in the antifouling coating composition of the present invention further comprises repeat units derived from (meth)acrylic acid ester monomers. Particularly preferred acrylic acetal ester copolymers comprise a residue of at least one monomer of formula (II):

wherein

R ⁷ is H or methyl;

R ⁸ is optionally substituted Ci_i ₈ alkyl, optionally substituted C _5-i o cycloalkyl, optionally substituted C _6-i o aryl or optionally substituted heterocyclyl, wherein said substituents are selected from OR ⁹ and heterocycyl;

R ⁹ is selected from H, Ci _-8 alkyl and (CH2CH2- _p (CH ₃ ) _p O) _q R ¹⁰ ;

R ¹⁰ is selected from H, Ci _-4 alkyl and phenyl;

p is 0 or 1 ; and

q is an integer from 1 to 20, preferably 1 to 6.

In some preferred monomers of formula (II), R ⁸ is unsubstituted C- _M8 alkyl. When R ⁸ is unsubstituted C- _MS alkyl, the alkyl group preferably comprises 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, e.g. 1 , 2, 3 or 4 carbon atoms. Preferred alkyl groups comprise 1 to 4 carbon atoms. Alkyl groups may be straight chained or branched, but straight chained alkyl groups are preferred.

When R ⁸ is unsubstituted C- _MS alkyl, the alkyl group may be linear or branched. When R ⁸ is unsubstituted C- _MS alkyl, R ⁸ is preferably selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, dodecyl and octadecyl. More preferred alkyl groups are methyl, ethyl, propyl, n-butyl and 2-ethylhexyl.

In some preferred monomers of formula (II), R ⁸ is substituted C- _MS alkyl. When R ⁸ is substituted C _MS alkyl, the alkyl group preferably comprises 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms, e.g. 1 , 2 or 3 carbon atoms. The alkyl group is preferred straight chained. Preferably the alkyl group is methyl or ethyl.

When R ⁸ is a substituted C _MS alkyl, the substituent may be heterocyclyl, OR ⁹ wherein R ⁹ is selected from H, Ci _-8 alkyl and (CH2CH2- _p (CH ₃ ) _p O) _q R ¹⁰ wherein R ¹⁰ is H or C-i-4 alkyl, p is 0 or 1 and q is an integer from 1 to 20, preferably 1 to 6, or N(R ¹¹ ) ₂ wherein each R ¹¹ is independently H or Ci _-6 alkyl.

When the alkyl group is substituted by a heterocyclyl, the heterocyclyl is preferably a 3- to 10-membered ring or ring system and more particularly a 5- or 6- membered ring, which may be saturated or unsaturated. Preferably the heterocyclyl is saturated. A representative example of a heterocyclyl group that may be present is glycidyl, tetra hydrofury I, pyrrolidonyl and morpholinyl.

When the alkyl group is substituted by OR ⁹ , R ⁹ is preferably selected from H and Ci _-8 alkyl (e.g. Ci _-3 alkyl) and (CH2CH _2-p (CH ₃ ) _p O)qR ¹⁰ wherein R ¹⁰ is Ci _-4 alkyl, p is 0 or 1 , and q is an integer from 1 to 20, preferably 1 to 6 and still more preferably Ci _-8 alkyl (e.g. Ci _-3 alkyl). Representative examples of R ⁹ include H, methyl, ethyl, (CH ₂ CH ₂ 0)CH ₃ and (CH ₂ CH ₂ 0)CH ₂ CH ₃ .

When the alkyl group is substituted by N(R ¹¹ ) ₂ , R ¹¹ is preferable independently selected from H or Ci _-6 alkyl, and preferably Ci _-6 alkyl. Representative examples of R ¹¹ include methyl and ethyl.

In further preferred monomers of formula (II), R ⁸ is unsubstituted C _5-i0 cycloalkyl. Preferred cyclic alkyl groups comprise 6 to 8 carbon atoms. Cycloalkyl groups may be a bridged or polycyclic ring system. Preferred cycloalkyl groups are monocyclic. When R ⁸ is unsubstituted C _5-i0 cycloalkyl, the cycloalkyl group is preferably selected from cyclopentyl, cyclohexyl, dicyclopentenyl and isobornyl. More preferred the cycloalkyl group is cyclohexyl.

In further preferred monomers of formula (II), R ⁸ is substituted C _5-i0 cycloalkyl. When R ⁸ is substituted C _5-i o cycloalkyl, the alkyl group preferably comprises 6 to 8 carbon atoms, e.g. 6 carbon atoms. The cycloalkyl group is preferably cyclohexyl. When R ⁸ is substituted C _5-i0 cycloalkyl, the substituent may be Ci _-8 alkyl or OR ⁹ wherein R ⁹ is selected from H and Ci _-8 alkyl.

When the cycloalkyl group is substituted by OR ⁹ , R ⁹ is preferably selected from H and Ci _-8 alkyl (e.g. Ci _-3 alkyl). Representative examples of R ⁹ include H, methyl and ethyl.

In further preferred monomers of formula (II), R ⁸ is unsubstituted C _6-i o aryl. When R ⁸ is unsubstituted C _6-i o aryl, the aryl group preferably comprises 6 or 10 carbon atoms. Preferred aryl groups include phenyl.

In further preferred monomers of formula (II), R ⁸ is substituted C _6-i o aryl. When R ⁸ is substituted C _6-i o aryl, the aryl group preferably comprises 6 or 10 carbon atoms. Preferred aryl groups include phenyl. When R ⁸ is substituted C _6-i o aryl, the substituent may be halogen, Ci _-8 alkyl or OR ⁹ wherein R ⁹ is selected from H, and Ci _-8 alkyl. More preferably the substituent is OR ⁹ wherein R ⁹ is selected from H and Ci _-8 alkyl.

When the C _6-i o aryl group is substituted by OR ⁹ , R ⁹ is preferably selected from H and Ci _-8 alkyl (e.g. Ci _-3 alkyl) Representative examples of R ¹⁰ include H, methyl and ethyl.

In further preferred monomers of formula (II), R ⁸ is C ₂ or C ₃ alkyl (e.g. ethyl or isopropyl) substituted by OR ⁹ wherein R ⁹ is (CH ₂ CH _2-p (CH ₃ ) _p O) _q R ¹⁰ wherein R ¹⁰ is selected from H, Ci _-4 alkyl and phenyl, p is 0 or 1 , and q is an integer from 1 to 20, preferably 1 to 6. Representative examples of R ¹⁰ include H, methyl and ethyl. In further preferred monomers of formula (II), R ⁸ is unsubstituted or substituted C- _MS alkyl and more preferably unsubstituted or substituted Ci _-8 alkyl. In particularly preferred monomers of formula (II), R ⁸ is selected from methyl, ethyl, propyl, n-butyl, 2- ethylhexyl and tetrahydrofurfuryl. When R ⁸ is substituted it is preferably substituted by OR ⁹ wherein R ⁹ is selected from methyl or (CH ₂ CH ₂ 0)CH ₂ CH ₃ .

Preferred monomers present in the copolymer present in the antifouling coating composition of the present invention include methyl acrylate, ethyl acrylate, tert-butyl acrylate, n-butyl acrylate, isobutyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, isooctyl acrylate, 2-propylheptyl acrylate, decyl acrylate, isodecyl acrylate, dodecyl acrylate, tridecyl acrylate, octadecyl acrylate, 2-hydroxyethyl acrylate, 2- hydroxypropyl acrylate, 4-hydroxybutyl acrylate, polyethylene glycol) acrylate, polypropylene glycol) acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-(2- ethoxyethoxy)ethyl acrylate, 2-(2-butoxyethoxy)ethyl acrylate, methoxy poly(ethylene glycol) acrylate, tetrahydrofurfuryl acrylate, 2-N-morpholinoethyl acrylate, N-(2- (acryloyloxy)ethyl)pyrrolidone, dimethylaminoethyl acrylate, methyl methacrylate, ethyl methacrylate, tert-butyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, isooctyl methacrylate, 2- propylheptyl methacrylate, decyl methacrylate, isodecyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, octadecyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, poly(ethylene glycol) methacrylate, polypropylene glycol) methacrylate, 2- methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, 2-(2-ethoxyethoxy)ethyl methacrylate, 2-(2-butoxyethoxy)ethyl methacrylate, methoxy polypthylene glycol) methacrylate, tetrahydrofurfuryl methacrylate, 2-N-morpholinoethyl methacrylate, N-(2- (methacryloyloxy)ethyl) pyrrolidone and dimethylaminoethyl methacrylate. Particularly preferably the monomers present in the copolymer present in the antifouling coating composition of the invention are selected from ethyl acrylate, n-butyl acrylate, 2- ethylhexyl acrylate, 2-methoxyethyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, tetrahydrofurfuryl acrylate, methyl methacrylate, n-butyl methacrylate, 2-methoxyethyl methacrylate and 2-(2-ethoxyethoxy)ethyl methacrylate. n-Butyl acrylate, tetrahydrofurfuryl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate and methyl methacrylate are particularly preferred monomers.

In preferred antifouling coating compositions of the present invention, the acrylic acetal ester copolymer comprises at least two (e.g. 2, 3 or 4) different (meth)acrylate monomers of formula (II) and more preferably 2 or 3 different (meth)acrylate monomers of formula (II). In some preferred compositions the copolymer comprises at least one monomer of formula (II) wherein R ⁷ is H and at least one monomer of formula (II) wherein R ⁷ is CH ₃ .

Preferably the acrylic acetal ester copolymer present in the antifouling coating composition of the invention does not comprise repeat units derived from acrylic acid and/or methacrylic acid.

Preferred acrylic acetal ester copolymer present in the antifouling coating composition of the present invention further comprises repeat units derived from other ethylenically unsaturated monomers. Representive examples of suitable ethylenically unsaturated monomers include styrene, vinyl acetate, 1-vinyl-2-pyrrolidone, 1-vinylcaprolactame, 3-dimethylaminopropyl methacrylamide, triisopropylsilyl acrylate, triisopropylsilyl methacrylate, 2-(trimethylsiloxy)ethyl methacrylate, zinc (meth)acrylate, zinc acetate (meth)acrylate, zinc neodecanoate (meth)acrylate.

The acrylic acetal ester copolymer present in the antifouling coating composition of the invention preferably comprises at least 15 wt% monomers of formula (I), based on the dry weight of the copolymer. More preferably the acrylic acetal ester copolymer comprises 15 wt% to 70 wt%, still more preferably 20 wt% to 60 wt% and yet more preferably 25 wt% to 55 wt% monomers of formula (I), based on the dry weight of the copolymer.

The acrylic acetal ester copolymer present in the antifouling coating composition of the invention preferably comprises at least 25 wt% monomers of formula (II), based on the dry weight of the copolymer. More preferably the acrylic acetal ester copolymer comprises 25 wt% to 85 wt%, still more preferably 35 wt% to 80 wt% and yet more preferably 40 wt% to 75 wt% monomers of formula (II), based on the dry weight of the copolymer.

Preferred acrylic acetal ester copolymers present in the antifouling coating composition of the present invention have a weight average molecular weight of 5,000 to 100,000, more preferably 15,000 to 60,000 and still more preferably 20,000 to 50,000. Preferred acrylic acetal ester copolymers present in the antifouling coating composition of the present invention have a glass transition temperature (Tg), preferably as measured according to the method set out in the examples, of 10 °C to 70 °C, more preferably 15 °C to 60 °C and still more preferably 20 °C to 50 °C. The antifouling coating composition may comprise one or more (e.g. 1 , 2, 3, 4 or 5) acrylic acetal ester copolymers as hereinbefore described. Preferred antifouling coating compositions of the present invention comprise 1 , 2, 3 or 4 acrylic acetal ester copolymers and still more preferably 1 or 2 acrylic acetal ester copolymer polymers.

Preferably the total amount of acrylic acetal ester copolymer present in the compositions of the invention is 2-60 wt%, more preferably 5-40 wt% and still more preferably 7-25 wt%, based on the total weight of the final composition (i.e. if the composition is supplied as a two-pack, these values refer to the wt% present in the final mixed composition).

Suitable acrylic acetal ester copolymers may be prepared using polymerization reactions known in the art. The acrylic acetal ester copolymer may, for example, be obtained by polymerizing at least one monomer of Formula (I) and one or more monomer of Formula (II) in the presence of a suitable polymerization initiator by any of various methods such as solution polymerization, bulk polymerization, emulsion polymerization, dispersion polymerization and suspension polymerization in a conventional manner or with controlled polymerization techniques. The acrylic acetal copolymer may be a random copolymer, an alternate copolymer, a gradient copolymer or block copolymer.

When preparing a coating composition using the acrylic acetal ester copolymer as hereinbefore described, the polymer is preferably diluted with an organic solvent to give a polymer solution having an appropriate viscosity. From this standpoint, it is desirable to employ solution polymerization to prepare the copolymer. Examples of suitable initiators for free-radical polymerization include azo compounds such as dimethyl 2,2’-azobis(2-methylpropionate), 2,2'-azobis(2-methylbutyronitrile), 2,2'- azobis(isobutyronitrile) and 1 ,T-azobis(cyanocyclohexane) and peroxides such as tert- butyl peroxypivalate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyoctanoate, tert-butyl peroxydiethylacetate, tert-butyl peroxyisobutyrate, di-tert-butyl peroxide, tert- butyl peroxybenozate, and tert-butyl peroxyisopropylcarbonate, tert-amyl peroxypivalate, tert-amyl peroxy-2-ethylhexanoate, 1 , 1 -di(tert-amyl peroxy)cyclohexane and dibenzoyl peroxide. These compounds may be used alone or as a mixture of two or more thereof.

Examples of suitable organic solvent include aromatic hydrocarbons such as xylene, toluene, mesitylene; ketones such as methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, methyl isoamyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone; esters such as butyl acetate, tert-butyl acetate, amyl acetate, propyl propionate, n-butyl propionate, isobutyl isobutyrate, ethylene glycol methyl ether acetate; ethers such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dibutyl ether, dioxane, tetrahydrofuran, alcohols such as n-butanol, isobutanol, benzyl alcohol; ether alcohols such as butoxyethanol, 1-methoxy-2-propanol, methyl isobutyl carbinol; hydrocarbons such as white spirit, limonene; and optionally a mixture of two or more solvents. These compounds are used alone or as a mixture of two or more thereof.

Alternatively suitable acrylic acetal ester copolymers may be purchased commercially.

Monocarboxylic acid

The antifouling coating compositions of the present invention may comprise a monocarboxylic acid. In such compositions the monocarboxylic acid reacts with a zinc compound in situ to produce a zinc salt of a monocarboxylic acid. Preferably the monocarboxylic acid is substantially entirely converted into a zinc salt in the composition of the present invention. In form of a zinc salt of a monocarboxylic acid, improvements to the drying rate of the coating or film may be achieved, along with film hardness.

The monocarboxylic acid present in the antifouling coating composition of the present invention preferably comprises 5 to 50 carbon atoms, more preferably 10 to 40 carbon atoms and still more preferably 12 to 25 carbon atoms.

The monocarboxylic acid present in the antifouling coating composition of the present invention is preferably selected from a resin acid, a derivative of a resin acid, C _6- 2o cyclic monocarboxylic acid, C _5- 24 acyclic aliphatic monocarboxylic acid, C7-20 aromatic monocarboxylic acid and mixtures thereof.

Representative examples of resin acids include abietic acid, neoabietic acid, dehydroabietic acid, palustric acid, levopimaric acid, pimaric acid, isopimaric acid, sandaracopimaric acid, communic acid and mercusic acid, secodehydroabietic acid. It will be appreciated that the resin acids are derived from natural sources and as such they typically exist as a mixture of acids. Resin acids are also referred to as rosin acids. Representative examples of sources of resin acids are gum rosin, wood rosin and tall oil rosin. Gum rosin, also referred to as colophony and colophonium, is particularly preferred. Preferred rosins are those comprising more than 85% resin acids and still more preferably more than 90% resin acids.

Commercial grades of rosin are often classified according to its colour by designation of letters on a colour scale XC (lightest), XB, XA, X, WW, WG, N, M, K, I,

H, G, F, E, D (darkest) as specified in ASTM D509. Preferred colour grades for the compositions of the invention are X, WW, WG, N, M, K, I, and still more preferably WW. Commercial grades of rosin typically have acid value from 155 to 180 mg KOH/g as specified in ASTM D465. Preferred rosin for the compositions of the invention has an acid value from 155 to 180 mg KOH/g, more preferred 160 to 175 mg KOH/g, even more preferred 160 to 170 mg KOH/g. Commercial grades of rosin typically have a softening point (Ring & Ball) of 70°C to 80°C as specified in ASTM E28. Preferred rosin for the compositions of the invention has a softening point of 70°C to 80°C, more preferred 75°C to 80°C

Representative examples of resin acid derivatives include partly hydrogenated rosin, fully hydrogenated rosin, disproportionated rosin, dihydroabietic acids, dihydropimaric acids and tetrahydroabietic acids

Representative examples of C _6- 2o cyclic monocarboxylic acids include naphthenic acid, 1 ,4-dimethyl-5-(3-methyl-2-butenyl)-3-cyclohexen-1-yl-carboxy lic acid,

I ,3-dimethyl-2-(3-methyl-2-butenyl)-3-cyclohexen-1 -yl-carboxylic acid, 1 ,2,3-trimethyl- 5-(1-methyl-2-propenyl)-3-cyclohexen-1-yl-carboxylic acid, 1 ,4,5-trimethyl-2-(2-methyl-

2-propenyl)-3-cyclohexen-1 -yl-carboxylic acid, 1 ,4,5-trimethyl-2-(2-methyl-1-propenyl)-

3-cyclohexen-1 -yl-carboxylic acid, 1 ,5,6-trimethyl-3-(2-methyl-1 -propenyl)-4- cyclohexen-1 -yl-carboxylic acid, 1 -methyl-4-(4-methyl-3-pentenyl)-4-cyclohexen-1 -yl- carboxylic acid, 1-methyl-3-(4-methyl-3-pentenyl)-3-cyclohexen-1 -yl-carboxylic acid, 2- methoxycarbonyl-3-(2-methyl-1-propenyl)-5,6-dimethyl-4-cyclo hexen-1 -yl-carboxylic acid, 1-i-propyl-4-methyl-bicyclo[2,2,2]2-octen-5-yl-carboxylic acid, 1-i-propyl-4-methyl- bicyclo[2,2,2]2-octen-6-yl-carboxylic acid, 6-i-propyl-3-methyl-bicyclo[2,2,2]2-octen-8- yl-carboxylic acid and 6-i-propyl-3-methyl-bicyclo[2, 2, 2]2-octen-7 -yl-carboxylic acid.

Representative examples of C _5-2 4 acyclic aliphatic monocarboxylic acids include Versatic™ acids, neodecanoic acid, 2,2,3,5-tetramethylhexanoic acid, 2,4-dimethyl-2- isopropylpentanoic acid, 2,5-dimethyl-2-ethylhexanoic acid, 2,2-dimethyloctanoic acid, 2,2-diethylhexanoic acid, pivalic acid, 2,2-dimethylpropionic acid, trimethylacetic acid, neopentanoic acid, 2-ethylhexanoic acid, isononanoic acid, 3,5,5-trimethylhexanoic acid, isopalmitic acid, isostearic acid, 16-methylheptadecanoic acid, 12,15- dimethylhexadecanoic acid. The acyclic aliphatic monocarboxylic acid is preferably selected from liquid, acyclic C10-24 monocarboxylic acids or liquid, branched C10-24 monocarboxylic acids. It will be appreciated that many of the acyclic C10-24 monocarboxylic acids may be derived from natural sources, in which case in isolated form they typically exist as a mixture of acids of differing chain lengths with varying degree of branching.

Suitable monocarboxylic acids may be purchased commercially.

Preferably the monocarboxylic acid is gum rosin, derivatives of gum rosin, acyclic C1 ₀ -24 monocarboxylic acids, C ₆ -2o cyclic monocarboxylic acids or mixtures thereof. A mixture of acid preferably contains at least one resin acid, gum rosin or derivative of gum rosin.

Preferably the total amount of monocarboxylic acid present in the compositions of the invention is 1-30 wt%, more preferably 2-20 wt% and still more preferably 3-15 wt%, based on the total weight of the composition.

Zinc compound

The antifouling coating composition of the present invention may also comprise a zinc compound and in particular a reactive zinc compound. In such compositions the zinc compound reacts with a monocarboxylic acid to produce a zinc salt of a monocarboxylic acid in situ. The reaction between the monocarboxylic acid and the zinc compound preferably occurs during production of the composition, during storage of the composition and/or during mixing of the paint prior to application of the paint. The presence of a zinc salt of monocarboxylic acid in the paint can be determined by, for example, FTIR-ATR spectroscopy. A zinc salt of a monocarboxylic acid produces a carbonyl stretch at 1580 cm ¹ .

The zinc compound provides Zn atoms or ions which interact with the monocarboxylic acid present in the composition. The interaction between zinc and the monocarboxylic acid improves the drying properties of the composition as well as the hardness of films formed therefrom.

Representative examples of zinc compounds include inorganic zinc compounds such as zinc oxide, zinc sulfide, zinc carbonate, zinc carbonate hydroxide, basic zinc carbonate, lithopone, sachtolith, hydrozincite, zinc spar, zinc vitrol, white vitrol, zinc white and coordination complex of zinc such as zinc pyrithione. Preferably the zinc compound is selected from inorganic zinc compounds and more preferred from zinc oxide, zinc carbonate hydroxide, zinc sulfide, hydrozincite and lithopone. The coating composition may contain one or more zinc compounds.

The zinc compound preferably has average particle size distribution of d50 below 50 pm, more preferably below 20 pm, and still more preferably below of 5 pm. The zinc compound preferably has average particle size distribution of d50 above 30 nm, more preferably above 100 nm, even more preferably above 300 nm. Preferably the zinc compound has an average particle size distribution of d50 of 30 nm to 50 pm, more preferably 300 nm to 20 pm and still more preferably 300 nm to 5 pm. The particle size and d50 is determined by laser diffraction methods as described in ISO 13320:2009.

The zinc compound preferably has a particle size of less than 100 pm, more preferably less than 50 pm and still more preferably less than 10 pm, preferably with a sieve residue of less than 0.05 wt% with a mesh size of 45 pm. The sieve residue is determined as described in ISO 787-7:2009.

Representative examples of commercial paint grade zinc compounds are Zinc oxide red seal from EverZinc; Zinc oxide KS-1 , Zinc oxide KS-2 from Hanil Chemical Ind. Co., Ltd.; Zinc oxide grade 210, Zinc oxide grade AZO 66 from U.S. Zinc; Sachtolith L, Sachtolith HD and Sachtolith HD-S from Sachtleben Chemie GmbH; Lithopone 30 DS, Lithopone 30 L, Lithopone 60 L from Venator Materials PLC; Zinc Carbonate AC, Zinc Oxide Red Seal and Zinc Oxide White Seal from Bruggemann Chemical; Zinc Omadine from Lonza; CleanBio Zinc from Kolon Life Science Inc.

Examples of zinc compounds, often present in antifouling coating compositions, which do not provide reactive zinc include zineb, zinc phosphate and zinc sulfate, as well as their hydrate forms.

Preferably the zinc compound is present in the compositions of the invention in an amount of 0.2-20 wt%, more preferably 0.5-15 wt% and still more preferably 1-10 wt%, based on the total weight of the composition. Preferably the molar ratio of zinc compound to monocarboxylic acid in the compositions of the invention is 20:1 to 1 :4, more preferably 15:1 to 1 :3 and still more preferably 10:1 to 1 :2, e.g. 8:1 to 1 :1.

Zinc salt of monocarboxylic acid

The antifouling composition of the present invention may comprise a zinc salt of a monocarboxylic acid. As described above, interaction between zinc and the monocarboxylic acid improves the drying properties of the composition as well as the hardness of films formed therefrom.

In such compositions the zinc salt is preferably formed from a monocarboxylic acid comprising 5 to 50 carbon atoms, more preferably 10 to 40 carbon atoms and still more preferably 12 to 25 carbon atoms.

More preferably the zinc salt is formed from a monocarboxylic acid selected from a resin acid, a derivative of a resin acid, C _6- 2o cyclic monocarboxylic acid, C _5- 24 acyclic aliphatic monocarboxylic acid, C _7-2 o aromatic monocarboxylic acid and mixtures thereof.

Representative examples of resin acids include abietic acid, neoabietic acid, dehydroabietic acid, palustric acid, levopimaric acid, pimaric acid, isopimaric acid, sandaracopimaric acid, communic acid and mercusic acid, secodehydroabietic acid. It will be appreciated that the resin acids are derived from natural sources and as such they typically exist as a mixture of acids. Resin acids are also referred to as rosin acids. Representative examples of sources of resin acids are gum rosin, wood rosin and tall oil rosin. Gum rosin, also referred to as colophony and colophonium, is particularly preferred. Preferred rosins are those comprising more than 85% resin acids and still more preferably more than 90% resin acids.

Commercial grades of rosin are often classified according to its colour by designation of letters on a colour scale XC (lightest), XB, XA, X, WW, WG, N, M, K, I, H, G, F, E, D (darkest) as specified in ASTM D509. Preferred colour grades for the compositions of the invention are X, WW, WG, N, M, K, I, and still more preferably WW. Commercial grades of rosin typically have acid value from 155 to 180 mg KOH/g as specified in ASTM D465. Preferred rosin for the compositions of the invention has an acid value from 155 to 180 mg KOH/g, more preferred 160 to 175 mg KOH/g, even more preferred 160 to 170 mg KOH/g. Commercial grades of rosin typically have a softening point (Ring & Ball) of 70°C to 80°C as specified in ASTM E28. Preferred rosin for the compositions of the invention has a softening point of 70°C to 80°C and more preferrably 75°C to 80°C

Representative examples of resin acid derivatives include partly hydrogenated rosin, fully hydrogenated rosin, disproportionated rosin, dihydroabietic acids, dihydropimaric acids and tetrahydroabietic acids

Representative examples of C _6- 2o cyclic monocarboxylic acids include naphthenic acid, 1 ,4-dimethyl-5-(3-methyl-2-butenyl)-3-cyclohexen-1-yl-carboxy lic acid, 1 ,3-dimethyl-2-(3-methyl-2-butenyl)-3-cyclohexen-1 -yl-carboxylic acid, 1 ,2,3-trimethyl- 5-(1-methyl-2-propenyl)-3-cyclohexen-1-yl-carboxylic acid, 1 ,4,5-trimethyl-2-(2-methyl-

2-propenyl)-3-cyclohexen-1 -yl-carboxylic acid, 1 ,4,5-trimethyl-2-(2-methyl-1-propenyl)-

3-cyclohexen-1 -yl-carboxylic acid, 1 ,5,6-trimethyl-3-(2-methyl-1 -propenyl)-4- cyclohexen-1 -yl-carboxylic acid, 1 -methyl-4-(4-methyl-3-pentenyl)-4-cyclohexen-1 -yl- carboxylic acid, 1-methyl-3-(4-methyl-3-pentenyl)-3-cyclohexen-1 -yl-carboxylic acid, 2- methoxycarbonyl-3-(2-methyl-1-propenyl)-5,6-dimethyl-4-cyclo hexen-1 -yl-carboxylic acid, 1-i-propyl-4-methyl-bicyclo[2,2,2]2-octen-5-yl-carboxylic acid, 1-i-propyl-4-methyl- bicyclo[2,2,2]2-octen-6-yl-carboxylic acid, 6-i-propyl-3-methyl-bicyclo[2,2,2]2-octen-8- yl-carboxylic acid and 6-i-propyl-3-methyl-bicyclo[2, 2, 2]2-octen-7 -yl-carboxylic acid.

Representative examples of C _5-2 4 acyclic aliphatic monocarboxylic acids include Versatic™ acids, neodecanoic acid, 2,2,3,5-tetramethylhexanoic acid, 2,4-dimethyl-2- isopropylpentanoic acid, 2,5-dimethyl-2-ethylhexanoic acid, 2,2-dimethyloctanoic acid, 2,2-diethylhexanoic acid, pivalic acid, 2,2-dimethylpropionic acid, trimethylacetic acid, neopentanoic acid, 2-ethylhexanoic acid, isononanoic acid, 3,5,5-trimethylhexanoic acid, isopalmitic acid, isostearic acid, 16-methylheptadecanoic acid, 12,15- dimethylhexadecanoic acid. The acyclic aliphatic monocarboxylic acid is preferably selected from liquid, acyclic C _10-24 monocarboxylic acids or liquid, branched C _10-24 monocarboxylic acids. It will be appreciated that many of the acyclic C _10-24 monocarboxylic acids may be derived from natural sources, in which case in isolated form they typically exist as a mixture of acids of differing chain lengths with varying degree of branching.

Suitable zinc salts of monocarboxylic acids may be purchased commercially.

Preferably the zinc salt is formed from a monocarboxylic acid selected from gum rosin, derivatives of gum rosin, acyclic C1 ₀ -24 monocarboxylic acids, C ₆ -2o cyclic monocarboxylic acids or mixtures thereof. More preferably the zinc salt is formed from a monocarboxylic acid selected from gum rosin and derivatives of gum rosin.

Preferably the zinc salt of a monocarboxylic acid is present in the compositions of the invention in an amount of 1-30 wt%, more preferably 2-20 wt% and still more preferably 3-15 wt%, based on the total weight of the composition. Preferably the molar ratio of zinc cations to monocarboxylic acid in the compositions of the invention is 20:1 to 1 :4, more preferably 15:1 to 1 :3 and still more preferably 10:1 to 1 :2, e.g. 8:1 to 1 :1. Antifouling agent

The antifouling coating composition of the present invention preferably comprises an antifouling agent. The terms antifouling agent, biologically active compounds, antifoulant, biocide, toxicant are used in the industry to describe known compounds that act to prevent marine fouling on a surface. The antifouling agent present in the compositions of the invention is preferably a marine antifouling agent. The antifouling agent may be inorganic, organometallic or organic. Suitable antifouling agents are commercially available.

Examples of inorganic antifouling agents include copper and copper compounds such as cuprous oxide, cupric oxide, copper sulfide, copper thiocyanate, copper powder and copper flakes.

Commercial paint grade cuprous oxide material typically has a particle diameter distribution of 0.1-70 pm and an average particle size (d50) of 1-25 pm. The cuprous oxide material may contain a stabilizing agent (e.g. to prevent surface oxidation and caking during storage and transportation). Representative examples of commercial available cuprous oxide include Nordox Cuprous Oxide Red Paint Grade, Nordox XLT from Nordox AS, Cuprous oxide from Furukawa Chemicals Co., Ltd.; Red Copp 97N, Purple Copp, Lolo Tint 97N, Chemet CDC, Chemet LD from American Chemet Corporation; Cuprous Oxide Red from Spiess-Urania; Cuprous oxide Roast, Cuprous oxide Electrolytic from Taixing Smelting Plant Co., Ltd.

Examples of organometallic antifouling agents include zinc pyrithione, copper pyrithione, zinc bis(dimethyldithiocarbamate) [ziram] and zinc ethylenebis(dithiocarbamate) [zineb].

Examples of organic antifouling agents include 2-(tert-butylamino)-4- (cyclopropylamino)-6-(methylthio)-1 ,3,5-triazine [cybutryne], 4,5-dichloro-2-n-octyl-4- isothiazolin-3-one [DCOIT], 2-(thiocyanatomethylthio)-1 ,3-benzothiazole [benthiazole], 3-(3,4-dichlorophenyl)-1 ,1- dimethylurea [diuron], N-dichlorofluoromethylthio-N',N'- dimethyl-N-phenylsulfamide [dichlofluanid], N-dichlorofluoromethylthio-N',N'-dimethyl- N-p-tolylsulfamide [tolylfluanid], N-(2,4,6-trichlorophenyl)maleimidepyridine triphenylborane [TPBP], 3-iodo-2-propynyl N-butylcarbamate [IPBC], 2, 4,5,6- tetrachloroisophthalonitrile [chlorothalonil], p-((diiodomethyl)sulfonyl) toluene, 4-bromo- 2-(4-chlorophenyl)-5-(trifluoromethyl)-1 H-pyrrole-3-carbonitrile [tralopyril] and 4-[1-(2,3- dimethylphenyl)ethyl]-1 H-imidazole [medetomidine] Other examples of antifouling agents include tetraalkylphosphonium halogenides, guanidine derivatives such as dodecylguanidine monohydrochloride; macrocyclic lactones including avermectins and derivatives thereof such as ivermectine; spinosyns and derivatives thereof such as spinosad; capsaicin and derivatives thereof such as phenylcapsaicin; and enzymes such as oxidase, proteolytically, hemicellulolytically, cellulolytically, lipolytically and amylolytically active enzymes.

Preferred antifouling agents are cuprous oxide, copper thiocyanate, copper pyrithione, zinc pyrithione, zinc ethylenebis(dithiocarbamate) [zineb], 2-(tert- butylamino)-4-(cyclopropylamino)-6-(methylthio)-1 ,3,5-triazine [cybutryne], 4,5-dichloro-

2-n-octyl-4-isothiazolin-3-one [DCOIT], N-dichlorofluoromethylthio-N',N'-dimethyl-N- phenylsulfamide [dichlofluanid], N-dichlorofluoro methylthio-N',N'-dimethyl-N-p- tolylsulfamide [tolylfluanid], 4-bromo-2-(4-chlorophenyl)-5-(trifluoromethyl)-1 H-pyrrole-

3-carbonitrile [tralopyril], 4-[1-(2,3-dimethylphenyl)ethyl]-1 H-imidazole [medetomidine] and phenylcapsaicin.

Especially preferred antifouling agents are cuprous oxide, copper thiocyanate, zinc pyrithione, copper pyrithione, zinc ethylenebis(dithiocarbamate) [zineb], 4,5- dichloro-2-n-octyl-4-isothiazolin-3-one [DCOIT], 4-bromo-2-(4-chlorophenyl)-5- (trifluoromethyl)-l H-pyrrole-3-carbonitrile [tralopyril] and 4-[1-(2,3- dimethylphenyl)ethyl]-1 H-imidazole [medetomidine].

The antifouling agents may be used alone or in mixtures as different antifouling agents operate against different marine fouling organisms. Mixtures of antifouling agents are generally preferred. One preferred mixture of antifouling agents is active against marine invertebrates, such as barnacles, tubeworms, bryozoans and hydroids; and plants, such as algae (seaweed and diatoms); and bacteria

Some preferred coating compositions of the present invention are essentially free of an inorganic copper antifouling agent. Such compositions preferably comprise a combination of tralopyril and one or more agents selected from zinc pyrithione, copper pyrithione, zineb, 4,5-dichloro-2-octyl-4-isothiazolin-3-one and medetomidine.

Other preferred coating compositions comprise cuprous oxide and/or copper thiocyanate and one or more agents selected from copper pyrithione, zineb, 4,5- dichloro-2-octyl-4-isothiazolin-3-one and medetomidine.

The combined amount of antifouling agents may form up to 60 wt% of the total coating composition, such as 0.1 to 50 wt%, e.g. 0.2 to 45 wt%, based on the total weight of the composition (i.e. based on both compoments when it is supplied as a 2K pack). Where inorganic copper compounds are present, a suitable amount of antifouling agent might be 5 to 60 wt% in the coating composition. Where inorganic copper compounds are avoided, lower amounts might be used such as 0.1 to 25 wt%, e.g. 0.2 to 10 wt%. It will be appreciated that the amount of antifouling agent will vary depending on the end use and the antifouling agent used. The use of these antifouling agents is known in antifouling coatings and their use would be familiar to the skilled man. The antifouling agent may be encapsulated or adsorbed on an inert carrier or bonded to other materials for controlled release. These percentages refer to the amount of active antifouling agent present and not therefore to any carrier used.

Pigment and/or extender

The antifouling coating composition of the present invention preferably comprises one or more extenders and/or pigments.

The term extender is used herein to encompass extenders as well as fillers. These compounds increase the bulk of the composition. Examples of extenders and fillers are minerals such as dolomite, plastorite, calcite, quartz, baryte, magnesite, aragonite, silica, wollastonite, talc, chlorite, mica, kaolin, perlite, and feldspar; synthetic inorganic compounds such as calcium carbonate, magnesium carbonate, barium sulfate, calcium silicate, zinc phosphate and silica (including colloidal silica, fumed silica, etc.); polymeric and inorganic microspheres such as uncoated or coated hollow and solid glass beads, uncoated or coated hollow and solid ceramic beads, hollow, porous and compact beads of polymeric materials such as poly(methyl methacrylate), poly(methyl methacrylate-co-ethylene glycol dimethacrylate), poly(styrene-co-ethylene glycol dimethacrylate), poly(styrene-co-divinylbenzene), polystyrene, poly(vinyl chloride).

The pigments may be inorganic pigments, organic pigments or a mixture thereof. Inorganic pigments are preferred. These compounds impart colour and hiding power to the composition. Examples of inorganic pigments include titanium dioxide, red iron oxide, yellow iron oxide, black iron oxide, zinc oxide, zinc sulfide, lithopone and graphite. Examples of organic pigments include carbon black, phthalocyanine blue, phthalocyanine green, napthol red, diketopyrrolopyrrolered. Pigments may optionally be surface treated to be more easily dispersed in the paint composition.

Preferred inorganic pigments include titanium dioxide and iron oxides. Preferably the total amount of extender, filler and/or pigment present in the compositions of the invention is 0-40 wt%, more preferably 2-35 wt% and still more preferably 5-30 wt%, based on the total weight of the composition. The skilled man will appreciate that the extender and pigment content will vary depending on the particle size distribution, the particle shape, the surface morphology, the particle surface-resin affinity, the other components present and the end use of the coating composition.

Cobinder

In addition to the acrylic acetal ester copolymer, an additional binder may optionally be used to adjust the properties of the antifouling coating composition.

Examples of other polymeric binders that can be used include:

acrylic resins such as homopolymers and copolymers of methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate n-butyl methacrylate, and isobutyl methacrylate;

hydrophilic polymers such as (meth)acrylate copolymers containing monomer units of hydroxyalkyl (meth)acrylate, alkoxyalkyl (meth)acrylate or alkylaminoalkyl (meth)acrylates; and homopolymers and copolymers of (meth)acrylamides, homopolymers and copolymers of 1-vinyl-2-pyrrolidinone and 1-vinylcaprolactam;

polyethylene oxides and polypropylene oxides;

vinyl ether homopolymers and copolymers, such as poly(methyl vinyl ether), poly(ethyl vinyl ether), poly(isobutyl vinyl ether), poly(n-butyl acrylate-co-isobutyl vinyl ether), poly(vinyl chloride-co-isobutyl vinyl ether);

polymeric plasticizers from any of the polymer groups specified above. The term polymeric plasticizer refers to polymers having a glass transition temperature (Tg) below 25°C.

Additional examples of other binders that may be present in the antifouling coating composition of the invention include:

silyl ester (meth)acrylate copolymers, such as copolymers comprising triisopropylsilyl (meth)acrylates;

metal (meth)acrylate copolymers, such as copolymers comprising zinc (meth)acrylate, zinc hydroxide (meth)acrylate, zinc neodecanoate (meth)acrylate or zinc oleate (meth)acrylate;

saturated aliphatic polyesters, such as poly(lactic acid), poly(glycolic acid), poly(2-hydroxybutyric acid), poly(3-hydroxybutyric acid), poly(4-hydroxyvaleric acid), polycaprolactone and aliphatic polyester copolymer containing two or more of the units selected from the above mentioned units;

polyoxalates as described in W02009100908;

alkyd resins and modified alkyd resins;

esters of gum rosin and hydrogenated gum rosin such as methyl esters of rosin, glycerol esters of rosin and pentaerythritol esters of rosin;

metal resinates of gum rosin and hydrogenated gum rosin such as alkaline earth metal resinate, e.g. magnesium resinate, calcium resinate, and transition metal resinate, e.g. zinc resinate, copper resinate; and

hydrocarbon resin, such as hydrocarbon resin formed from the polymerisation of at least one monomer selected from a C5 aliphatic monomer, a C9 aromatic monomer, an indene coumarone monomer, or a terpene or mixtures thereof.

Especially suitable additional binders are acrylic resins, esters of gum rosin and polymeric plasticizers.

Preferably the cobinder is present in the compositions of the invention in an amount of 0-15 wt%, more preferably 0.5-10 wt% and still more preferably 1-7 wt%, based on the total weight of the composition.

Solvent

The antifouling coating composition of the present invention preferably comprises a solvent. The solvent is preferably volatile. Preferably the solvent is organic. That said the components of the antifouling coating composition can alternatively be dispersed in an organic non-solvent for the film-forming components (i.e. the polymers) in the coating composition or in an aqueous dispersion. Suitable solvents for use in the compositions of the invention are commercially available.

Examples of suitable organic solvents and thinners are aromatic hydrocarbons such as xylene, toluene, mesitylene; ketones such as methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, methyl isoamyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone; esters such as butyl acetate, tert-butyl acetate, amyl acetate, isoamyl acetate, propyl propionate, n-butyl propionate, isobutyl isobutyrate; ether esters such as ethylene glycol methyl ether acetate, propylene glycol methyl ether acetate, ethyl 3-ethoxypropionate; ethers such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dibutyl ether, dioxane, tetrahydrofuran; ether alcohols such as butoxyethanol, 1-methoxy-2-propanol; alcohols such as n-butanol, isobutanol, methyl isobutyl carbinol, benzyl alcohol; hydrocarbons such as white spirit and limonene; and optionally a mixture of two or more solvents and thinners.

The total amount of solvent present in the antifouling coating compositions of the present invention is preferably as low as possible as this minimizes the VOC content. Preferably the total solvent present in the compositions of the invention is 0- 40 wt%, more preferably 10-35 wt% and still more preferably 15-30 wt% based on the total weight of the composition. The skilled man will appreciate that some raw materials comprise solvent and contribute to the total solvent content as specified above and thus that the solvent content added will vary depending on the other components present.

Dehydrating agent and stabilizers

The antifouling coating compositions of the present invention optionally comprise a dehydrating agent, also referred to as water scavenger or drying agent. Preferably the dehydrating agent is a compound which removes water from the composition in which it is present. Dehydrating agents improve the storage stability of the antifouling coating compositions by removing moisture introduced from raw materials, such as pigments and solvents, or water formed by reaction between carboxylic acid compounds and metal oxide, metal hydroxide or metal carbonate compounds in the antifouling coating composition. The dehydrating agents that may be used in the antifouling coating compositions include organic and inorganic compounds.

The dehydrating agents may be hygroscopic materials that absorb water or bind water as crystal water. These are often referred to as desiccants. Examples of such compounds include calcium sulfate hemihydrate, anhydrous calcium sulfate, anhydrous magnesium sulfate, anhydrous sodium sulfate, anhydrous zinc sulfate, molecular sieves and zeolites.

The dehydrating agents may also be compounds that chemically react with water. Examples of dehydrating agents that react with water include orthoesters such as trimethyl orthoformate, triethyl orthoformate, tripropyl orthoformate, triisopropyl orthoformate, tributyl orthoformate, trimethyl orthoacetate triethyl orthoacetate, tributyl orthoacetate and triethyl orthopropionate; ketals; acetals; enolethers; orthoborates such as trimethyl borate, triethyl borate, tripropyl borate, triisopropyl borate, tributyl borate and tri-tert-butyl borate; oxazolidines such as 3-ethyl-2-methyl-2-(3-methylbutyl)- 1 ,3-oxazolidine and 3-butyl-2-(1-ethylpentyl)-1 ,3-oxazolidine; monofunctional isocyanates, such as p-toluenesulfonyl isocyanate and organosilanes such as trimethoxymethylsilane, triethoxymethylsilane, phenyltrimetoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, tetraethoxysilane and ethyl polysilicate.

Stabilizers are preferably acid scavengers that contribute to the storage stability of the antifouling coating composition. Example of stabilizers include carbodiimide compounds, such as bis(2,6-diisopropylphenyl)carbodiimide and bis(2- methylphenyl)carbodiimide and others as described in patent application W02014064049; amine compounds, such as trihexylamine, triheptylamine, tris(2- ethylhexyl)amine, triisooctylamine, tribenzylamine and 1-methylimidazole.

Preferably the dehydrating agents and stabilizers are each present in the compositions of the invention in an amount of 0-5 wt%, more preferably 0.5-2.5 wt% and still more preferably 1.0-2.0 wt%, based on the total weight of the composition.

Additive

The antifouling coating composition of the present invention preferably comprises one or more other components. Examples of other components that can be added to the antifouling coating composition are reinforcing agents, rheology modifiers, dispersing agents, wetting agents and plasticizers.

Examples of reinforcing agents are flakes and fibres. Fibres include natural and synthetic inorganic and organic fibres, e.g. as described in WO00/77102. Representative examples include mineral fibres such as mineral-glass fibres, wollastonite fibres, montmorillonite fibres, tobermorite fibres, atapulgite fibres, calcined bauxite fibres, volcanic rock fibres, bauxite fibres, rockwool fibres, and processed mineral fibres from mineral wool.

Preferably, the fibres have an average length of 25 to 2,000 mhh and an average thickness of 1 to 50 mhh with a ratio between the average length and the average thickness of at least 5. Preferably reinforcing agents are present in the compositions of the invention in an amount of 0-20 wt%, more preferably 0.5-15 wt% and still more preferably 1-10 wt%, based on the total weight of the composition.

Examples of classes of rheology modifiers optionally present in the compositions of the invention include thixotropic agents, thickening agents and anti- settling agents. Representative examples of rheology modifiers are silicas such as fumed silicas, organo-modified clays, amide waxes, polyamide waxes, amide derivatives, polyethylene waxes, oxidized polyethylene waxes, hydrogenated castor oil wax, ethyl cellulose, aluminium stearates and mixtures of thereof. Thixotropic agents, thickening agents and anti-settling agents that need activation may be added to the coating composition as is and activated during the paint production process or they can be added to the coating composition in a pre-activated form, e.g. solvent paste.

Preferably thixotropic agents, thickening agents and anti-settling agents are each present in the composition of the invention in an amount of 0-5.0 wt%, more preferably 0.2-3.0 wt% and still more preferably 0.5-2.0 wt%, based on the total weight of the composition.

Examples of plasticizers are chlorinated paraffins, silicone oils (non-reactive polydimethylsiloxane), phthalates, phosphate esters, sulfonamides, adipates and epoxidized vegetable oils. Preferably plasticizers are present in the compositions of the invention in an amount of 0-10 wt%, more preferably 0.5-7 wt% and still more preferably 1-5 wt%, based on the total weight of the final composition.

Composition and paint

Some preferred antifouling coating compositions of the invention comprise:

(i) 2-60 wt%, and more preferably 5-40 wt%, acrylic acetal ester copolymer;

(ii) 1-30 wt%, and more preferably 2-20 wt%, zinc salt of a monocarboxylic acid.

Further preferred antifouling coating compositions of the invention comprise:

(i) 2-60 wt%, and more preferably 5-40 wt%, acrylic acetal ester copolymer;

(ii) 1-30 wt%, and more preferably 2-20 wt%, zinc salt of a monocarboxylic acid;

(iv) 0.1-50 wt%, and more preferably 0.2-45 wt %, antifouling agent;

(v) 0-40 wt%, and more preferably 2-35 wt %, pigment and/or extender;

(vi) 0-15 wt%, and more preferably 0.5-10 wt %, cobinder;

(vii) 0-35 wt%, and more preferably 1-30 wt %, solvent;

(viii) 0-5 wt%, and more preferably 0.5-2.5 wt%, stabilizer;

(ix) 0-5 wt%, and more preferably 0.5-2.5 wt%, dehydrating agent; and

(x) 0-5 wt%, and more preferably 0.2-3 wt% rheology modifier.

Other preferred antifouling coating compositions of the invention comprise:

(i) 2-60 wt%, and more preferably 5-40 wt%, acrylic acetal ester copolymer;

(ii) 1-30 wt%, and more preferably 2-20 wt%, monocarboxylic acid compound; and (iii) 0.2-20 wt%, and more preferably 0.5-15 wt%, zinc compound.

Further preferred antifouling coating compositions of the invention comprise:

(i) 2-60 wt%, and more preferably 5-40 wt%, acrylic acetal ester copolymer;

(ii) 1-30 wt%, and more preferably 2-20 wt%, monocarboxylic acid compound;

(iii) 0.2-20 wt%, and more preferably 0.5-15 wt%, zinc compound;

(iv) 0.1-50 wt%, and more preferably 0.2-45 wt %, antifouling agent;

(v) 0-40 wt%, and more preferably 2-35 wt %, pigment and/or extender;

(vi) 0-15 wt%, and more preferably 0.5-10 wt %, cobinder;

(vii) 0-35 wt%, and more preferably 1-30 wt %, solvent; and

(viii) 0-5 wt%, and more preferably 0.5-2.5 wt%, stabilizer;

(ix) 0-5 wt%, and more preferably 0.5-2.5 wt%, dehydrating agent; and

(x) 0-5 wt%, and more preferably 0.2-3 wt% rheology modifier.

The present invention also relates to a method of preparing the composition as hereinbefore described wherein the components present in the composition are mixed. Any conventional production method may be used.

The composition as described herein may be prepared in a suitable concentration for use, e.g. spray painting. In this case, the composition is itself a paint. Alternatively the composition may be a concentrate for preparation of paint. In this case, further solvent is added to the composition described herein to form paint. Preferred solvents are as hereinbefore described in relation to the composition.

After mixing, and optionally after addition of solvent, the antifouling coating composition or paint is preferably filled into a container. Suitable containers include cans, drums and tanks.

The antifouling coating compositions of the present invention may be supplied as a one pack or a multi-pack, e.g. as a two-pack. Preferably the composition is supplied as a two-pack.

When supplied as a one-pack, the composition is preferably supplied in a ready-mixed or ready to use form. Optionally the one-pack product may be thinned with solvents prior to application. This composition preferably comprises an acrylic acetal ester copolymer and a zinc salt of a monocarboxylic acid.

When supplied as a two pack, the first container preferably contains an acrylic acetal ester copolymer as hereinbefore defined and optionally a stabilizer and the second container preferably contains a monocarboxylic acid and a zinc compound. The monocarboxylic acid and zinc compound react in situ to generate a zinc salt of the monocarboxylic acid. When supplied as a two pack, the contents of the first and second containers are preferably mixed immediately prior to use of the composition. Preferably the conversion to zinc salt of the monocarboxylic acid is completed in the second container prior to mixing. Optionally further solvent is added to the composition to form the paint. Preferred solvents are as hereinbefore described in relation to the composition.

The present invention therefore also relates to kits for preparation of a paint as hereinbefore described. A first kit for the preparation of paint comprises: a first container containing an acrylic acetal ester copolymer and optionally a stabilizer; a second container containing a zinc salt of a monocarboxylic acid and optionally a dehydrating agent; and optionally instructions for mixing the contents of said first and second containers. A further kit for the preparation of paint comprises a first container containing an acrylic acetal ester copolymer and optionally a stabiliser; a second container containing a monocarboxylic acid and a zinc compound; and optionally instructions for mixing the contents of said first and second containers. In both kits, preferably the first container also contains pigment and/or extender. In both kits pigment and/or extender, antifouling agent, cobinder, solvent and additive(s) are optionally present in the first container, second container or both containers. Preferred acrylic acetal ester copolymer, monocarboxylic acid, zinc compound, stabilizer, antifouling agent, pigment and/or extender, cobinder, solvent and additive(s) are as described above in relation to the overall antifouling coating composition. Preferred kits further comprise instructions for mixing the contents of the first and second containers.

The antifouling coating composition and paint of the invention preferably has a solids content of 40-80 vol%, more preferably 45-70 vol% and still more preferably 50- 65 vol%.

Preferably the antifouling coating composition and paint of the invention has a viscosity of 50-1500 cP, more preferably 100-1000 cP and still more preferably 150- 800 cP. Preferably viscosity is measured using a Cone and Plate viscometer (ISO 2884-1 :1999) as described in the examples.

Preferably the antifouling coating composition and paint of the invention has a content of volatile organic compounds (VOC) of 50 to 500 g/L, preferably 100 to 420 g/L, e.g. 150 to 380 g/L. VOC content can be calculated as described in e.g. ASTM D5201-05 or IED 2010/75/EU or measured as described in e.g. US EPA Method 24 or ISO 11890-2. The antifouling coating composition of the present invention may be produced by employing processes well known to the skilled person in the art. For example, the antifouling coating composition may be prepared by simultaneously or sequentially adding (in any order) the components of the composition and then agitating, mixing and/or dispersing the components within the composition. Any conventional mixing methods may be employed, including methods that apply high shear forces to the mixture, e.g. high-speed dispersers, various mills and in-line mixers.

In preferred processes for preparing the compositions of the invention any pigments, extenders and/or antifouling agents and rheology modifiers that require dispersion and/or activation are mixed with solvents in a first step, preferably using a high shear mixer. Sometimes this step is referred to as milling, grinding or dispersing. Optionally other ingredients, e.g. acrylic acetal ester copolymer, a zinc salt of a monocarboxylic acid or zinc compound and monocarboxylic acid, binders, stabiliser and/or dehydrating agent are also included in the milling process. In one preferred process the acrylic acetal ester copolymer, a zinc salt of a monocarboxylic acid, an antifouling agent, optionally a stabiliser, optionally a dehydrating agent and optionally solvents are mixed with a milled mixture of pigments and/or extenders, antifouling agents, binders and/or rheology modifiers. The various components may be added simultaneously or sequentially (in any order). Preferably the resulting mixture is further mixed by agitating, mixing and/or dispersing. This method produces 1 K product.

In a preferred method for producing 2K product, a first mixture is prepared by milling an acrylic acetal ester copolymer, optionally a stabiliser, optionally a dehydrating agent, and optionally any pigments and/or extenders, binders and rheology modifiers that require activation and/or dispersion and optionally solvents. A second mixture is separately prepared by milling a monocarboxylic acid and a zinc compound that reacts with the mononocarboxylic acid to produce a zinc salt of the monocarboxylic acid, and optionally any pigments and/or extenders, binders and rheology modifiers that require activation and/or dispersion and optionally solvents. The two resulting compositions are ultimately mixed together to form the antifouling coating composition. This final mixing step is preferably done immediately prior to use of the antifouling composition.

The antifouling coating composition and paint of the invention can be applied to a whole or part of any article surface which is subject to fouling. The surface may be permanently or intermittently underwater (e.g. through tide movement, different cargo loading or swell). The article surface will typically be the hull of a vessel or surface of a fixed marine object such as an oil platform or buoy. Application of the coating composition and paint can be accomplished by any convenient means, e.g. via painting (e.g. with brush or roller) or more preferably spraying the coating onto the article. Typically the surface will need to be separated from the seawater to allow coating. The application of the coating can be achieved as conventionally known in the art. After the coating is applied, it is preferably dried or cured.

When applying the antifouling coating to an object (e.g. a ship hull) the surface of the object is typically not protected solely by a single coat of antifouling composition. Depending on the nature of the surface the antifouling coating may be applied directly to an existing coating system. Such a coating system may comprise several layers of paint of different generic types (e.g. epoxy, polyester, vinyl or acrylic or mixtures thereof). If the surface is a clean and intact antifouling coating from a previous application, the new antifouling paint can be applied directly, typically as one or two coats and with more in exceptional cases.

Alternatively, the applicator may start with an uncoated surface (e.g. steel, aluminium, plastic, composite, glass fiber or carbon fiber). To protect such a surface, the full coating system will typically comprise one or two layers of an anticorrosive coating (e.g. curable epoxy coating or curable modified epoxy coating), one layer of tie- coat (e.g. curable modified epoxy coating or physical drying vinyl coating) and one or two layers of antifouling paint. The person skilled in the art will be familiar with these coating layers. In exceptional cases additional antifouling paint layers may be applied.

Some preferred articles of the invention therefore comprise a coating on at least a part of a surface thereof, wherein the coating comprises an anticorrosive coating layer such as a primer, a tie layer and an antifouling coating composition as herein defined.

The invention will now be defined with reference to the following non limiting examples. EXAMPLES

Methods for characterization of polymers and determination of polymer properties and polymer solution properties

Determination of polymer solution viscosity

The viscosity of the polymer solutions was determined in accordance with ASTM D2196-15 using a Brookfield DV-I Prime digital viscometer with LV-2 or LV-4 spindle at 12 rpm. The polymers were tempered to 23.0°C ± 0.5°C before the measurements.

Determination of non-volatile matter content of the polymer solutions

The solids content in the polymer solutions was determined as the non-volatile content by mass in accordance with ISO 3251 :2008. A test sample of 0.5 g ± 0.1 g was transferred to a flat-bottomed metal dish and dried in a ventilated oven at 105°C for 180 minutes. The weight of the residual material is considered to be the non-volatile matter (NVM). The non-volatile matter content of the sample is expressed in weight percent. The value given is the average of three parallels. Determination of polymer average molecular weights distribution

The polymers were characterised by Gel Permeation Chromatography (GPC) measurement. The molecular weight distribution (MWD) was determined using a Malvern Omnisec Resolve and Reveal system with two PLgel 5 pm Mixed-D columns from Agilent in series. The columns were calibrated by conventional calibration using narrow polystyrene standards. The analysis conditions were as set out in the table below.

Samples were prepared by dissolving an amount of polymer solution corresponding to 25 mg dry polymer in 5 ml. THF. The samples were kept for a minimum of 3 hours at room temperature prior to sampling for the GPC measurements. Before analysis the samples were filtered through 0.45 pm Nylon filters. The weight- average molecular weight (Mw) and the polydispersity index (PDI), given as Mw/Mn, are reported.

Determination of the glass transition temperature

The glass transition temperature (Tg) was obtained by Differential Scanning

Calorimetry (DSC) measurements. The DSC measurements were performed on a TA Instruments DSC Q200. The sample was prepared by drawdown of the polymer solution on a glass panel using an applicator with 100 pm gap size. The glass panel was dried over night at room temperature and subsequently 24 hours at 50 °C in a ventilated heating cabinet. The dry polymer material was scraped off the glass panels and approx. 10 mg of the dry polymer material was transferred to an aluminium pan. The pan was sealed with a non-hermetic lid. The measurement was performed by running a heat-cool-heat procedure, within a temperature range from -80 °C to 120 °C, with a heating rate of 10 °C/min and cooling rate of 10 °C/min and using an empty pan as reference. The recorded data from the temperature scans were processed using Universal Analysis software from TA Instruments. The inflection point of the glass transition range, as defined in ASTM E1356-08, of the second heating is reported as the Tg of the polymers. Determination of the acid value by colorimetric titration

The acid value of carboxylic acid compounds was determined according to the procedure described in ISO 2114:2000 Method A. A weighted quantity of carboxylic acid compound, approx. 1 g, was dissolved in approx. 50 ml. Jotun Thinner No. 17. Phenolphthalein was added as colour indicator and the solution was titrated with 0.1 M KOH solution in ethanol until a red colouration appeared and was stable for 10-15 s while the solution was stirred. The reported acid value is the average value of three parallels measurements. For carboxylic acid compound in solution the acid value for the dry carboxylic acid compound was calculated based on measured non-volatile matter of the tested carboxylic acid compound solution.

General procedure for preparation of copolymer solutions A1 and A2

Solvents were charged to a reactor fitted with a stirrer, a condenser, a feed inlet and a nitrogen inlet. The reactor content was heated to 85 °C and maintained at that temperature. The feed, which consisted of a mixture of monomers, solvents and initiator, was added to the reactor at a constant rate over 2 hours. One hour after the feed addition was completed, a mixture of solvents and initiator were added. The reaction mixture was kept at 85 °C for another two hours before the reactor was cooled.

The ingredients for preparing the copolymers are listed in Table 1 below. All amounts are given in parts by weight.

General procedure for preparation of copolymer solutions A3-A12

Solvents were charged to a reactor fitted with a stirrer, a condenser, a feed inlet and a nitrogen inlet. The reactor content was heated to 85 °C and maintained at that temperature. The feed, which consisted of a mixture of monomers and initiator, was added to the reactor at a constant rate over 3 hours. One hour after the feed addition was completed, a mixture of solvents and initiator were added. The reaction mixture was kept at 85 °C for another two hours before a quantity of solvent was added and the reactor was cooled.

The ingredients for preparing the copolymers are listed in Table 1 below. All amounts are given in parts by weight. o

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Table 1 : Acetal ester copolymers (amounts in parts by weight)

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Procedure for preparation of copolymer solution CA1

Production example B-2 of WO2016/167360 was repeated to prepare copolymer solution CA1.

Following the procedure of WO2016/167360, 75 parts of xylene was charged to a temperature-controlled reaction vessel equipped with a stirrer, a condenser, a nitrogen inlet and a feed inlet. The reaction vessel was heated and maintained at 85 °C while the content was stirred. A mixture of 10 parts methyl methacrylate, 40 parts 2- methoxyethyl methacrylate, 50 parts 1-isobutoxyethyl methacrylate and 1.3 parts 2,2'- azobis(isobutyronitrile) was prepared. The mixture was added to the reaction vessel over a period of 4 hours at constant rate under a nitrogen atmosphere. After the addition was completed, a mixture of 0.5 parts t-butyl peroxyoctanoate and 2 parts xylene was added four times at an interval of 30 minutes. The reactor content was further stirred for 1 hour at 85 °C. Then 7.1 parts isobutyl vinyl ether, 6.7 parts xylene and 3 parts butyl acetate were added and the reaction vessel was cooled to room temperature.

Copolymer solution A3 had non-volatile matter content of 51.3 wt%, solution viscosity of 307 cP, Mw 25 200, PDI 2.34 and measured Tg of 37°C.

Procedure for preparation of copolymer solution CA2

Reference example 5 (polymer a-4) of JPH04-103671 was repeated to prepare copolymer solution CA2.

Following the procedure of JPH04-103671 , 800 parts of xylene was charged to a temperature-controlled reaction vessel equipped with a stirrer, a condenser, a nitrogen inlet and a feed inlet. The reaction vessel was heated and maintained at 110 °C while the content was stirred. A mixture of 200 parts xylene, 15 parts t-butyl peroxyoctanoate, 5 parts 2,2'-azobis(isobutyronitrile), 300 parts methyl methacrylate, 200 parts n-butyl acrylate and 500 parts 1-isobutoxyethyl methacrylate was prepared. The mixture was added to the reaction vessel over a period of 5 hours at constant rate under a nitrogen atmosphere. After the addition was completed the reactor content was stirred for a further 5 hours at 110 °C. The reaction vessel was cooled to room temperature.

Copolymer solution A4 had non-volatile matter content of 50.1 wt%, solution viscosity of 357 cP, Mw 11 200, PDI 2.39 and measured Tg of 31 °C. Procedure for preparation of acrylic copolymer solution X1

48.0 Parts of xylene and 20.0 parts of 1-methoxy-2-propanol were charged to a temperature-controlled reaction vessel equipped with a stirrer, a condenser, a feed inlet and a nitrogen inlet. The reaction content was heated to 85 °C and maintained at that temperature. A pre-mix of 93.0 parts n-butyl acrylate, 4.0 parts methyl methacrylate, 3.0 parts methacrylic acid, 1.58 parts 2,2’-azobis(2-methylbutyronitrile) and 20.0 parts xylene was prepared and added to the reactor at a constant rate over 2 hours and 30 minutes under a nitrogen atmosphere. One hour after the feed addition was completed, a mixture of 0.30 parts 2,2’-azobis(2-methylbutyronitrile) and 10.0 parts xylene was added to the reaction vessel at a constant rate over 15 minutes. The reaction mixture was kept at 85 °C for another hour before the reactor was cooled to room temperature. The amounts of ingredients are given in parts by weight.

The acrylic copolymer solution had non-volatile content of 49.9 wt%, solution viscosity of 98 cP. The acrylic copolymer had Mw 28 700, PDI 3.12, measured Tg of -35°C and acid value of 18.6 mg KOH / g dry polymer.

Procedure for preparation of zinc salt of gum rosin Z1

1400 g solution of Portuguese gum rosin (60 % by weight in xylene; acid number 109 mg KOH/g solution, determined by the method described in the example section), 220 g zinc oxide and 60 g xylene were charged to a 2 L temperature- controlled reaction vessel equipped with a stirrer, a Dean-Stark trap and a reflux condenser. The reaction mixture was heated to reflux. The reaction mixture was refluxed at 140-160°C until no more water condensed in the Dean-Stark trap. The excess zinc oxide was allowed to settle before the solution of gum rosin zinc salt was filtered.

The filtrated zinc rosinate solution had a non-volatile matter content of 66.9 wt%.

Procedure for preparation of trimethyl isobutenyl cvclohexene carboxylic acid

Trimethyl isobutenyl cyclohexene carboxylic acid was prepared based on the procedure described in CN 1039801 12.

54 parts methacrylic acid, 102 parts freshly distilled alloocimene and 0.1 parts 4-methoxyphenol was added to a reaction flask equipped with stirrer, condenser and nitrogen inlet. The reaction mixture was put under nitrogen before being heated to 90 °C. After 72 hours of reaction, 103 parts alloocimene was added and the reaction mixture was kept at 140 °C for 1 1 hours to complete the reaction. The product was purified by vacuum distillation, a first distillation at 137-150 °C, 3 mbar for the crude product and a second distilliation at 140-147 °C, 3 mbar for the product.

The product was a pale yellow, transparent, semi-solid material at room temperature. The product had an acid value of 246 mg KOH/g.

The product was a mixture of isomers of trimethyl isobutenyl cyclohexene carboxylic acid. The other compounds employed in the antifouling coating compositions exemplified herein are summarised in tables 2a and 2b below. These compounds were all purchased from commercial suppliers.

Table 2a: Zinc compounds

Table 2b

Determination of antifouling coating composition properties and properties of coatings formed therefrom Determination of paint viscosity using Cone and Plate viscometer

The viscosity of the antifouling coating compositions were determined according to ISO 2884-1 :1999 using a REL Digital Cone and Plate viscometer set at a temperature of 23 °C, working at a shear rate of 10 000 s ¹ and providing viscosity measurement in the range of 0-10 P. The result is given as the average of three measurements. Determination of VOC

The VOC (g/L) of the antifouling coating compositions was calculated according to ASTM D5201-05.

Determination of Koniq pendulum hardness of coating film

The hardness of the coating film was determined using a pendulum hardness tester. The tests were performed according to ISO 1522:2006.

Each of the antifouling coating compositions was applied to a transparent glass plate (100x200x3 mm) using a film applicator with 300 pm gap size. The coating films were dried at 23°C, 50% relative humidity for 1 week and then dried at 50°C for 72 hours in a ventilated heating cabinet. The coating film hardness of the dry coating film was measured at a temperature of 23°C using an Erichsen 299/300 pendulum hardness tester after 24 hours of drying and after forced drying in the heating cabinet. The hardness is quantified as the number of pendulum swings to damp the amplitude from 6° to 3°. A higher number of swings indicates a higher hardness of the coating.

Determination of the polishing rates of antifoulinq coating films on rotating disc in seawater

The polishing rate was determined by measuring the reduction in film thickness of a coating film over time. For this test PVC discs were used. The coating compositions were applied as radial stripes on the disc using a film applicator with a gap size of 300 pm. The thicknesses of the dry coating films were measured by a surface profiler. Typical initial dry film will depend on the solids content of the applied antifouling coating composition and the speed of application. Typical initial film thickness for the tested coatings in the example part was 100 ± 15 pm. The PVC discs were mounted on a shaft and rotated in a container in which seawater was flowing through. Natural seawater which had been filtered and temperature-adjusted to 25°C ± 2°C was used. The speed of the rotated shaft provides an average simulated speed of 16 knots on the disc. The PVC disc was taken out at regular intervals for measuring the film thickness. The disc was dried overnight at room temperature before measuring the film thicknesses. The results are given as film consumption, i.e. the difference between the initial film thickness and the measured thickness at the given time. The coating film is considered to be polished through when a thin, non-polishing leached layer was remaining on the surface, typically 10-20 pm in thickness, or when the film was totally polished away from the surface. Polishing through is denoted as PT. Coating failure by detachment of the coating film and flaking is denoted as FL. General procedure for preparation of antifoulinq coating compositions

The components were mixed in the proportions given in Tables 3, 5, 7-8, 10 and 12-13 below. The mixture was dispersed in the presence of glass beads (approx. 3-4 mm in diameter) in a paint can of 250 ml using a vibrational shaker for 15 minutes. Solid resins were dissolved in a portion of the solvent, giving a resin solution of 50-60 wt% solids, before the remaining ingredients were added and the mixtures were dispersed. The compositions described in Tables 3a, 3b, 5, 7, 10 and 13 were each initially prepared as two components (Component A and Component B) in separate paint cans (each 250 ml) and were mixed in the given ratio shortly before application.

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Table 3a: 2K antifouling coating compositions. The ingredients are given in parts by weights. O n

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Table 3b: Comparative 2K antifouling coating compositions. The ingredients are given in parts by weights.

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Table 4: Results for pendulum hardness and reduction in film thickness of antifouling coatings

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Table 5: 2K antifouling coating compositions and comparative examples. The ingredients are given in parts by weights.

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Table 6: Results for pendulum hardness and reduction in film thickness of antifouling coatings

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Table 7: 2K antifouling coating compositions. The ingredients are given in parts by weights.

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Table 8: Replicate antifouling coating compositions disclosed in prior art. The ingredients are given in parts by weights.

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Table 9: Results for pendulum hardness and reduction in film thickness of antifouling coatings

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Table 10: 2K Cu-free antifouling coating compositions. The ingredients are given in parts by weights.

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Table 11 : Results for pendulum hardness and reduction in film thickness of antifouling coatings

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Table 12: 1 K antifouling coating compositions. The ingredients are given in parts by weights.

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Table 13: 2K antifouling coating compositions. The ingredients are given in parts by weights.

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Table 14: Results for reduction in film thickness of antifouling coatings

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Results

The patent examples illustrate a range of antifouling coating compositions of the present invention. The examples demonstrate the improved film hardness achieved with the antifouling coating compositions of the invention.

The results in Table 4 show that with both different types and different amounts of reactive zinc compounds used in the antifouling coating compositions tested, the pendulum hardness of films formed with the compositions of the invention is relatively high, both at 24 hours after application and in the dried film. These results may be compared to those for comparative examples CPA1 to CPA4 which lack a reactive zinc compound and therefore produce much less hard films 24 hours after application and after drying. The results also show that the coatings formed from the antifouling coating compositions of the invention polish at a controlled rate whereas the coatings formed from the comparative examples either polish away or the polishing rate levels off.

The results in Table 6 show that with both different types and different amounts of monocarboxylic acid compounds used in the antifouling coating compositions tested, the pendulum hardness of films formed with the compositions of the invention is relatively high, both at 24 hours after application and in the dried film. These results may be compared to those for comparative examples CPB1 to CPB3 which contained the same types of monocarboxylic acid compounds but lack a reactive zinc compound and therefore produce much less hard films 24 hours after application and after drying. The results also show that the coatings formed from the antifouling coating compositions of the invention polish at a controlled rate whereas the coatings formed from the comparative examples ultimately fail.

The results in Table 9 show that different formulations variables, e.g. different acetal ester copolymer, different cobinder, different biocides and different extenders, used in the antifouling coating compositions tested, the pendulum hardness of films formed with the compositions of the invention is relatively high, both at 24 hours after application and in the dried film. The results also show that the coatings formed from the antifouling coating compositions of the invention polish at a controlled rate.

CPC2 and CPC3 replicate compositions disclosed in the prior art. These compositions both lack a reactive zinc compound. As shown in Table 9, these compositions all produce films with much lower hardness levels (at 24 hours and after drying) than the compositions of the invention. CPC1 is a further comparative which is the same as CPC2 but additionally lacks the monocarboxylic acid compound. Additionally the coatings formed from the comparative compositions either polish away or the polishing rate levels off.

The results in Table 11 show that with copper-free antifouling coating compositions, the pendulum hardness of films formed with the compositions of the invention is relatively high, both at 24 hours after application and in the dried film. The results also show that the coatings formed from the copper free antifouling coating compositions of the invention polish at a controlled rate. These results may be compared to the comparative example which produces much less hard films 24 hours after application and after drying. Moreover the coating formed from the comparative example fails in the polishing test.

The results in Table 14 show that a range of acrylic acetal ester copolymers may be employed in the antifouling coating compositions of the present invention and produce films having a relatively high pendulum hardness and controlled polishing rate. The compositions exemplified include one-pack and two-pack compositions.