WO2025051850A1 - Antifouling coating system - Google Patents

Abstract

An antifouling coating system comprising a primer layer (I) and antifouling coating layer (II) directly adjacent thereto, wherein: the primer layer (I) is formed from a primer composition comprising components A and B, wherein component A comprises: i) 15 to 70 wt% of one or more epoxy-based binders relative to the total weight of component A; and ii) 20 to 60 wt% water, relative to the total weight of component A; wherein component B comprises: i) an amine based curing agent; and ii) a silane; and wherein component B comprises less than 5 wt% water, relative to the total weight of component B; and wherein the antifouling layer (II) is formed from an antifouling coating composition comprising: a) a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer; and b) at least 1.0 wt% based on dry weight of the total composition, of rosin or a rosin derivative; wherein the antifouling coating composition comprises at least 5 wt% water relative to the total weight of the antifouling coating composition as a whole.

Description

Antifouling coating system

The present invention relates to an anticorrosive and antifouling coating system, more specifically to a waterborne anticorrosive and antifouling coating system comprising a waterborne primer and a waterborne antifouling coating composition applied directly thereon. In particular, the waterborne anticorrosive primer comprises an aqueous epoxy-based binder in a first component (component A) and a curing agent and a silane in a second component (component B). Preferably, the waterborne antifouling coating composition comprises a polymeric binder and a rosin or rosin derivative. The invention further relates to a process for applying the anticorrosive and antifouling coating system of the invention to a substrate, use of the coating system of the invention to protect an object from corrosion and fouling and to substrates coated with the coating system of the invention.

Background of invention

Surfaces that are submerged in seawater are subjected to fouling by marine organisms such as green and brown algae, barnacles, mussels, tube worms and the like. On marine constructions such as vessels, oil platforms, buoys, etc. 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 will increase 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. These paints generally comprise a film-forming binder, together with different components such as pigments, fillers, additives and solvents together with biologically active substances (biocides).

Commercial vessels (e.g. container ships, bulk carriers, tankers, passenger ships) often operate in different waters, in different trade, with different activity, including idle periods. The antifouling coating should provide good fouling protection under all those conditions. Typical service intervals for commercial vessels are from 30 to 90 months. Maintenance of submerged objects is costly, so the applied antifouling coatings should be effective for the specified service interval.

Many antifouling coating compositions are known but many of the current commercial solutions are under threat due to tightening legislation on volatile organic compounds. Stricter volatile organic compounds (VOC) regulations limit the amount of organic solvents that can be used in coating systems. Typical coating systems used on ships and in submerged areas usually comprise one to two coats of epoxy primer, one coat of tie-coat and one to four coats of an antifouling coating, all of which are usually solvent borne. The total VOC content for all these layers can be high.

The use of a solvent free primer is known but that still leaves the tie coat and antifouling coating composition with potentially high levels of VOC. Although low in VOC content, a solvent-free primer may have slower curing speed than a waterborne primer, a short overcoating interval and problems with blushing when cured at low temperatures and high relative humidity.

A different solution to this problem would be to use a waterborne epoxy primer but no such primer is currently available, that also has a sufficiently high anti-corrosive performance to be used in submerged areas.

Conventional antifouling coating systems use a tie coat to link the primer layer to the antifouling layer. Elimination of the tie-coat from such a system would obviously reduce the total VOC emissions however the use of a tie-coat is necessary in coating systems containing a solvent-borne antifouling coating composition and a solvent-borne or solvent-free epoxy primer to ensure a good adhesion between the primer coating and antifouling coating. Alternatively, elimination of the anticorrosive epoxy primer from such a system could also be a solution to reduce the total VOC emissions of the system. However, using only a tie-coat between the steel substrate and antifouling would not provide sufficient corrosion protection.

In addition to increasing the total emission of VOC the use of a tie-coat also adds to the workload at the application site as an extra layer of paint must be applied to the substrate. The application of the tie coat also takes extra time as it is possible that the primer layer has to dry and potentially cure before application of the tie coat and the tie coat has to dry and potentially cure before application of the antifouling coating composition. For a large vessel, extra time in dry dock is expensive.

By improving the compatibility between the anti-fouling coating and primer one could in theory be able to produce a tie-coat free coating system with a performance that is sufficient to be used on objects such as off-shore installations and ships, thus reducing workload, VOC emissions and cost in newbuild and maintenance situations.

To the authors knowledge, there are no commercially available solvent free or waterborne antifouling paints or tie-coats on the marked suitable for industrial use.

It will be appreciated that any attempt to reduce VOC content cannot be at the expense of practicality. The most common application methods for antifouling coating systems are airless spray, brush or roller. It is important that the paint can be applied by standard techniques which in turn means coating compositions and paints having a certain viscosity level. Some products are transported in a form that is too viscous for application (but are of low VOC). These products are diluted shortly before application to a substrate. The VOC limits are still regarded as exceeded if additional organic solvents must be added to reduce the viscosity at the point of application.

It is a challenge to find coating compositions which comply with the evertightening VOC regulations and which also have controlled polishing properties, good mechanical properties and interlayer adhesion, and exhibit good fouling protection.

One solution for achieving VOC compliant and more sustainable coatings is to use waterborne (WB) technology. The waterborne market will likely increase to offer more sustainable coatings to meet VOC and hazardous air pollutants (HAP) regulations. Water-based paints have gained popularity in the interior market due to low odour, easier clean-up, faster drying and the fact that such paints are healthier for the user.

Some WB primers are known. Although WB epoxy primers offer a route to lower VOC, they are generally regarded to be expensive and to have a lower performance than comparable solvent borne and solvent free epoxy primers, and is typically considered not to be suitable for use on immersed objects. This means that the customer would not likely buy waterborne epoxy primers if not forced to do so out of other concerns such as environmental legislation and VOC regulation. Another drawback with waterborne paints is the risk of bad film formation at adverse curing conditions, mainly conditions where it takes a long time before the water evaporates, for instance at low temperatures and high relative humidity. The consequence of improper film formation can be severe as it often requires removing the coating before repainting.

It is an object of the invention to provide a new waterborne coating system which addresses as least some of the above-mentioned issues. Some coating systems comprising water borne paints are described in the literature but none which use a water borne primer with a water borne antifouling coating.

The present inventors have unexpectedly found that the coating systems of the present invention offer a solution to high VOC content whilst still providing the performance which any antifouling coating system requires. The coating system of the present invention comprises a waterborne epoxy primer and a waterborne antifouling coating applied directly thereon in the absence of a tie coat. The antifouling coating system has good inter-coat adhesion/compatibility when combined in a coating system without the use of a tie-coat. The coating system of the present invention has low environmental burden ( i.e. containing low concentration of organic solvents), excellent antifouling properties and excellent anti-corrosive performance. The present invention significantly reduces VOC emissions compared to currently used coating systems. The present invention also reduces the workload and logistics in the paint application phase due to a reduction in the required number of coats for a suitable system. Furthermore, due to short drying time, the use of a WB primer also makes it possible to apply several coats in one shift, which reduces the time it takes to apply the whole coating system.

Summary of Invention Viewed from a first aspect, the invention provides antifouling coating system comprising a primer layer (I) and antifouling coating layer (II) directly adjacent thereto, wherein: primer layer (I) comprises, such as consists of, a primer composition comprising components A and B, wherein component A comprises: i) 15 to 70 wt% of one or more epoxy-based binders relative to the total weight of component A; and ii) 20 to 60 wt% water, relative to the total weight of component A; wherein component B comprises: i) an amine based curing agent; and ii) a silane; and wherein component B comprises less than 5 wt% water, relative to the total weight of component B; and antifouling layer (II) comprising, such as consisting of, of an antifouling coating composition comprising: a) a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer; and b) at least 1.0 wt% based on dry weight of the total composition, of rosin or a rosin derivative; wherein the antifouling coating composition comprises at least 5 wt% water relative to the total weight of the antifouling coating composition as a whole.

It will be appreciated that in order to form primer layer (I) the components A and B are mixed to form the composition that is applied to a substrate. The amounts of each ingredient refer therefore to the wet component before they are mixed.

The ultimate antifouling coating system may be regarded as a cured and dried analogue of the antifouling coating system described above.

Alternatively viewed, the invention provides antifouling coating system comprising a primer layer (I) and antifouling coating layer (II) directly adjacent thereto, wherein: the primer layer (I) is formed from a primer composition comprising components A and B, wherein component A comprises: i) 15 to 70 wt% of one or more epoxy-based binders relative to the total weight of component A; and ii) 20 to 60 wt% water, relative to the total weight of component A; wherein component B comprises: i) an amine based curing agent; and ii) a silane; and wherein component B comprises less than 5 wt% water, relative to the total weight of component B; and wherein the antifouling layer (II) is formed from an antifouling coating composition comprising: a) a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer; and b) at least 1.0 wt% based on dry weight of the total composition, of rosin or a rosin derivative; wherein the antifouling coating composition comprises at least 5 wt% water relative to the total weight of the antifouling coating composition as a whole.

Alternatively viewed, the invention provides a process for the preparation of an antifouling coating system comprising a primer layer (I) and antifouling coating layer (II) directly adjacent thereto, wherein said process comprises: obtaining a component A comprising: i) 15 to 70 wt% of one or more epoxy-based binders relative to the total weight of component A, such as a bisphenol type epoxy resin; and ii) 20 to 60 wt% water, relative to the total weight of component A; obtaining a component B comprising: i) an amine based curing agent; and ii) a silane, such as an amino functional silane; and wherein component B comprises less than 5 wt% water, relative to the total weight of component B; applying on a substrate a blend of components A and B so as to form a primer layer (I), and obtaining an antifouling coating composition comprising: a) a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer; and b) at least 1.0 wt% based on dry weight of the total composition, of rosin or a rosin derivative; wherein the antifouling coating composition comprises at least 5 wt% water relative to the total weight of the antifouling coating composition as a whole; and applying said antifouling coating composition onto said primer layer (I) to form an antifouling coating layer (II) directly adjacent thereto.

All embodiments described below with reference to the antifouling coating system apply also to this process for its manufacture.

Viewed from another aspect, the invention provides a process for applying a coating system as hereinbefore defined to a substrate comprising applying, e.g. by spraying, primer layer (I) as hereinbefore defined to a substrate and allowing the coating composition to cure and/or dry then applying, e.g. by spraying, antifouling coating layer (II) as hereinbefore defined directly on top of layer (I) and allowing the coating composition to dry. Both layers may be allowed to cure and/or dry at any time during the application process.

In a further aspect, the invention provides a process for protecting an object from corrosion and/or fouling, said process comprising coating at least a part of said object which is subject to fouling with an antifouling coating composition as hereinbefore defined.

Viewed from a further aspect, the invention provides use of the coating system as hereinbefore defined to protect an object from fouling.

Viewed from another aspect, the invention provides a substrate coated with a cured coating system as hereinbefore defined.

Viewed from another aspect the invention provides an antifouling coating system that is tie coat free comprising a water borne epoxy primer layer (I) and a water borne antifouling coating layer (II) applied directly thereon. Viewed from another aspect the invention provides a substrate having a dry primer layer (I) comprising one or more epoxy-based binders, such as a bisphenol type epoxy resin; an amine based curing agent; and a silane, such as an amino functional silane; and a wet antifouling coating layer (II) directly adjacent thereto, wherein: said wet antifouling coating layer (II) comprises a) a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer; and b) at least 1.0 wt% based on dry weight of the total composition, of rosin or a rosin derivative; wherein the antifouling coating composition comprises at least 5 wt% water relative to the total weight of the antifouling coating composition as a whole.

Viewed from another aspect the invention provides a substrate having a wet primer layer (I) comprising one or more epoxy-based binders, such as a bisphenol type epoxy resin; an amine based curing agent; and a silane, such as an amino functional silane; and a wet antifouling coating layer (II) directly adjacent thereto, wherein: wet antifouling coating layer (II) comprises a) a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer; and b) at least 1.0 wt% based on dry weight of the total composition, of rosin or a rosin derivative; wherein the antifouling coating composition comprises at least 5 wt% water relative to the total weight of the antifouling coating composition as a whole.

Definitions

The invention relates to an antifouling coating system. The term antifouling coating system defines a multilayer coating comprising at least a primer layer (I) and an antifouling layer (II) directly thereon. Primers for metal (steel) substrates are applied to prevent corrosion, and to aid in the adhesion of subsequent coats. Primers that are applied to prevent corrosion are termed anti-corrosive primers. Primer layer (I) of use in the present invention should therefore act to prevent corrosion of a metal substrate beneath. The term primer therefore refers to a composition that, when applied to a substrate prevents corrosion of said substrate and increases the adhesion to subsequent coats like topcoats and antifouling coats.

The invention avoids the use of a tie layer. A tie layer is sometimes added to act as an adhesive layer between a primer layer and a top layer above where direct application of the top layer to a primer layer is not possible. In this invention, the antifouling coating composition can be applied directly to the anticorrosive primer layer without the use of a tie layer. Tie coats do not act to prevent corrosion and are not therefore formulated with anticorrosive properties - they are not therefore primers.

Tie coats can be based on two component epoxy compositions, and in addition a thermoplastic resin being solid at room temperature is added to modify the binder system. Examples of such solid thermoplastic resins include chlorinated polyolefins, acrylic resins, vinyl acetate resins, butyl acetate resins, styrene resins and vinyl chloride resins. The content of the thermoplastic resin is typically 10- 90wt% relative to the epoxy resin content of the tie coat composition.

The antifouling coating system of the invention may therefore comprise 2 layers or more, preferably two layers only. It may be that to develop a suitable film thickness multiple coats are required to establish any of the layers. We regard the application of multiple coats of the same composition as forming a single layer in the antifouling coating system.

The terms “marine antifouling coating composition” and “antifouling coating composition” refer to a composition that, when applied to a surface, prevents or minimises growth of marine organisms on the surface. The antifouling coating composition that is used to form antifouling coating layer (II) is one that preferably contains therefore a biocide.

As used herein, the term “waterborne composition” refers to a composition which comprises water as the continuous phase and main solvent in the ready-to- apply paint, i.e. paint where all the necessary components are mixed together. Typically, water forms at least 50 wt% of the solvent contained in the formulation, preferably at least 55 wt% of the solvent is water. It will be appreciated that the claims define the layers (I) and (II) in terms of the composition that is applied to a substrate. That composition contains solvent that will evaporate and a curing/drying process may occur in order to form the eventual final paint on the substrate.

As used herein the term “binder” or “binder system” defines the part of the composition which includes the polymeric binder and any other polymers/polymer- forming substances, resins or components which together form a matrix giving substance and strength to the composition. Rosin or rosin derivatives of the present invention are regarded as part of the binder system in the antifouling coating composition. The one or more epoxy-based binders of the primer composition are the main binders in the primer composition, i.e. they form at least 50 wt% of the binders present, preferably at least 60 wt%.

As used herein, equivalent weight pertains to the mass in grams of a reactive compound having a number of reactive groups equivalent to 1 mol. For epoxy resin based binders the equivalent weight is denoted epoxy equivalent weight (EEW) and for amine-based curing agents the equivalent weight is denoted active hydrogen equivalent weight (AHEW). Thus, the contribution from each of the epoxy-based binders, or other epoxy functional components, to the number of epoxy equivalents in the composition is defined as grams of epoxy-based compound divided by the epoxy equivalent weight of the epoxy-based compound. Likewise, for the amine- based curing agent or other compounds with active amine hydrogens, the contribution to the number of active hydrogens in the composition is defined as grams of amine functional compound divided by the active hydrogen equivalent weight of the amine functional compound.

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

As used herein, the term emulsion refers to a fine suspension of droplets of one liquid in another in which it is not soluble or miscible. In the context of the present invention, the emulsions may be termed “oil-in-water” emulsions, i.e. wherein the dispersed phase consists of an oil-phase and the continuous phase is water. Thus, the emulsions employed in the present invention may also be termed “aqueous emulsions”, meaning that they are emulsions wherein the continuous phase (i.e. the solvent) comprises water.

As used herein, the term dispersion refers to a fine suspension of solid or semisolid particles in a continuous phase, in which it is not soluble or miscible. In the context of the present invention, the dispersion may be termed “oil-in-water” dispersions if the dispersed phase consists of an oil-phase, i.e. resin, and the continuous phase is water. Thus, the dispersions employed in the present invention may also be termed “aqueous dispersions”, meaning that they are dispersions wherein the continuous phase (i.e. the solvent) comprises water.

As used herein the term filler refers to a compound which increases the volume or bulk of a coating composition. The fillers are substantially insoluble in the coating composition and are dispersed therein.

The term “(meth)acrylate” means a methacrylate or acrylate.

The term “hydrocarbyl group” refers to any group containing C atoms and H atoms only and therefore covers alkyl, alkenyl, aryl, cycloalkyl, arylalkyl groups and so on.

As used herein the term “alkyl” refers to saturated, straight chained, branched or cyclic groups.

As used herein the term “cycloalkyl” refers to a cyclic alkyl group.

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

As used herein the term “alkenyl” refers to unsaturated, straight chained, branched or cyclic groups.

As used herein the term “aryl” refers to a group comprising at least one aromatic ring. The term aryl encompasses fused ring systems wherein one or more aromatic ring is fused to a cycloalkyl ring. An example of an aryl group is phenyl, i.e. C₆H₅.

As used herein the term “alkaryl” refers to a group comprising an aromatic ring that is substituted with an alkyl radical. An example is methyl-, ethyl- or higher alkyl phenyls. As used herein the term "substituted" refers to a group wherein one or more, for example up to 6, more particularly 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.

As used herein the term “arylalkyl” group refers to structural motifs comprising an aromatic ring with at least one alkyl moiety attached to the aromatic ring and wherein substituent e.g., amines are attached to the alkyl portion.

As used herein the term “polyether” refers to a compound comprising two or more -O- linkages interrupted by alkylene units.

As used herein the terms “poly(alkylene oxide)”, “poly(oxyalkylene)” and “poly(alkylene glycol)” refer to a compound comprising -alkylene-O- repeating units. Typically the alkylene is ethylene or propylene.

As used herein the term “volatile organic compound (VOC)” refers to a compound having a boiling point of 250 °C or less.

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

As used herein “antifouling agent” or “biocide” refers to a biologically active compound or mixture of biologically active compounds that prevents the settlement of marine organisms on a surface, and/or prevents the growth or marine organisms on a surface and/or encourages the dislodgement of marine organisms on a surface. These terms are used interchangeably. A biocide is defined by the European biocidal products regulation (BPR) as an active substance intended to destroy, deter, render harmless, prevent the action of, or otherwise exert a controlling effect on any harmful organism by chemical or biological means.

The term “Tg” means glass transition temperature, obtained by Differential Scanning Calorimetry (DSC) measurements.

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.

The term “wt% based on the total dry weight of the composition” refers to the wt% of a component present in the composition relative to the total weight of the components in the composition not including the solvents. Detailed description of Invention

The present invention relates to an antifouling coating system for preventing corrosion and fouling on an object, preferably a marine structure such as a ship.

The antifouling coating system comprises at least a primer layer (I) and an antifouling coating layer (II). Ideally, the antifouling coating system comprises one or more primer layers and one or more antifouling coating layers only. For example, two or more different antifouling coating compositions may be applied but the only layers present are primer and antifouling layers. In some cases, the coating system consists of two layers only.

The antifouling coating layer is applied directly on the primer layer so the primer layer and antifouling layer are adjacent layers.

Primer Layer (I)

Layer (I) comprises, such as consists of, a primer composition comprising components A and B. Layer (I) is therefore formed by the application of primer composition to a substrate and the layer that forms acts to prevent corrosion of the substrate. All components within layer (I) should be part of component A or component B.

Layer (I) is also referred to as the primer layer. Component A comprises one or more epoxy-based binders and water, and component B comprises an amine- based curing agent and a silane. Component B comprises less than 5 wt% water and ideally no water.

The primer layer will be described in terms therefore of the primer composition and in particular components A and B that are applied to the substrate to form the ultimate primer layer after drying/curing.

Component A - Epoxy-based binder

Component A comprises one or more epoxy-based binders and water. Component A comprises one or more epoxy-based binders, which may be preferably selected from aromatic or aliphatic epoxy-based binders, preferably comprising more than one epoxy group per molecule. The epoxy-groups may be in an internal or terminal position on the epoxy-based binder or on a cyclic structure incorporated into the epoxy-based binder. Preferably the epoxy-based binder comprises at least two epoxy groups so that a crosslinked network can be formed by reaction with a curing agent that has at least three sites reactive towards epoxy groups.

Suitable aliphatic epoxy-based binders include epoxy and modified epoxy binders selected from cycloaliphatic diglycidyl ethers such as diglycidyl ethers based on hydrogenated bisphenol A, hydrogenated bisphenol F, and dicyclopentadiene, glycidyl ethers such as polyglycidyl ethers of polyhydric alcohols, epoxy functional acrylic resins or any combinations thereof.

Suitable aromatic epoxy-based binders include epoxy and modified epoxy binders selected from bisphenol type epoxy-based binders such as the diglycidyl ethers of bisphenol A, bisphenol F and bisphenol S, resorcinol diglycidyl ether (RDGE), novolac type epoxy-based binders such as epoxy phenol novolac resins, epoxy cresol novolac resins and bisphenol A epoxy novolac resins, glycidyl ethers of dihydroxynaphtalenes or any combinations thereof.

In one preferred embodiment the one or more epoxy-based binder is an aromatic epoxy-based binder. Preferably the aromatic epoxy-based binder is derived from a combination of a compound comprising a least one epoxide functionality with an aromatic co-reactant comprising at least two hydroxyl groups.

Preferred epoxy binders are bisphenol epoxy binders. Preferred epoxy-based binders are bisphenol A and bisphenol F epoxy-based binders or bisphenol A/F epoxy binders. In one particularly preferred embodiment the epoxy-based binder is a bisphenol A epoxy-based binder.

The one or more epoxy-based binder may comprise a modified epoxy-based binder. Preferably the epoxy-based binder may be modified with fatty acids, acrylic acids, acrylic polymers, polypropylene oxide, polyethylene oxide, alcohols, carboxylic acids or acid anhydrides, or a combination thereof.

In neat form, i.e., before the epoxy-based binder is dissolved or dispersed in any solvent, and at ambient temperature (18 to 25 °C), the one or more epoxy-based binder is in a liquid, semi-solid or solid form, or a mixture thereof. The epoxy equivalent weight (EEW) of the neat epoxy-based binder is preferably 160 to 1500 g/eq, more preferably 170 to 1000 g/eq, even more preferred 180 to 800 g/eq and most preferred 190 to 600 g/eq.

In one embodiment the primer composition may comprise more than one epoxy-based binder such as an epoxy-based binder containing a mixture of two or more different epoxy resins.

In one embodiment the primer composition may comprise an epoxy-based binder having an EEW in neat form of 160 to 250 g/eq. such as a liquid epoxy based binder.

In one embodiment the primer composition may comprise an epoxy-based binder having an EEW in neat form of 450 to 600 g/eq, such as a solid epoxy based binder.

The one or more epoxy-based binder may also be dispersed or emulsified in water. Appropriate chemical modifications may be performed on the binder, i.e. to improve water compatibility or to increase flexibility. The water-based dispersions or emulsions comprising the epoxy-based binder may comprise other components such as emulsifiers, (reactive)diluents, organic solvents, stabilizers, defoamers, dispersing agents and biocides.

When dispersed or emulsified in water, the one or more epoxy-based binders are in the form of particles or droplets. These particles or droplets may be considered the dispersed phase and the solvent (i.e. aqueous solvent) may be considered the continuous phase. It will be understood that an aqueous solvent is one comprising (preferably consisting of) mainly water.

The water-based dispersions or emulsions comprising the epoxy-based binder preferably have a solid content of 20 to 80 wt%, more preferably 40 to 75 wt%, most preferred 45 to 75 wt%.

The solvent (preferably comprising water in the amounts as defined above) forms 20 to 80 wt% of the dispersions or emulsions, relative to the total weight of the dispersions or emulsions as a whole. Typical wt% ranges may be 25 to 60 wt%, such as 25 to 55 wt%, relative to the total weight of the dispersion or emulsion as a whole. The epoxy-based binder particles or droplets will typically have an average diameter of 4 to 2000 nm, preferably 25 to 1500 nm, more preferably 50 to 1000 nm, such as 100 to 900 nm. The “diameter” referred to in this context is the Z- average size, which will be understood to be the intensity weighted mean size as determined by ISO 22412:2017 using a Malvern Zetasizer Nano S instrument.

The dispersion or emulsion may be prepared by any suitable known method in the art.

The dispersion or emulsion may comprise emulsifying agents. The emulsifying agent may be non-ionic, anionic, cationic or amphoteric, preferably non-ionic.

Examples of non-ionic emulsifiers are alkyl phenoxy ethers, polyalkylene glycols, polysorbates, alkoxylated polysorbates, polyvinyl alcohols, polyvinyl esters, and polyether siloxanes. Examples of preferred non-ionic emulsifying agents may be polyalkylene glycols such as polyoxy ethylene-polyoxypropylene co-polymers.

Examples of anionic emulsifying agents are alkyl-, aryl-, alkaryl- sulphates, other than sulphonates, phosphates, sulphosuccinates, sulphosuccinamates, sulphoacetates, acid anhydrides, carboxylic acids and amino acid derivatives.

Typical anionic emulsifying agents may be alkylbenzenesulfonate salts, alkyl ether sulfate salts, polyoxyethylene alkyl ether sulfate salts, polyoxyethylene alkylphenyl ether sulfate salts, alkylnaphthylsulfonate salts, unsaturated aliphatic sulfonate salts, and hydroxylated aliphatic sulfonate salts. The alkyl group referenced here can be exemplified by medium and higher alkyl groups such as decyl, undecyl, dodecyl, tridecyl, tetradecyl, cetyl, stearyl, and so forth. The unsaturated aliphatic group can be exemplified by oleyl, nonenyl, and octynyl. The counterion can be exemplified by sodium ion, potassium ion, lithium ion, and ammonium ion, with the sodium ion being typically used among these.

Typical cationic emulsifying agents can be exemplified by quaternary ammonium salt-type surfactants such as alkyltrimethylammonium salts, e.g., octadecyltrimethylammonium chloride and hexadecyltrimethylammonium chloride, and dialkyldimethylammonium salts, e.g., dioctadecyldimethylammonium chloride, dihexadecyldimethylammonium chloride and didecyldimethylammonium chloride. The amphoteric surfactant can be exemplified by alkylbetaines and alkylimidazolines.

It is particularly preferred that the emulsifying agent is a non-ionic type.

The dispersions or emulsions may also comprise curing catalysts, antifoaming agents, preservatives, pH adjusting agents and buffers.

It is preferred therefore if the epoxy-based binder is provided as a dispersion or an emulsion. The epoxy dispersions or emulsions that are preferred for use in the invention are bisphenol-based and are either chemically modified to become emulsifiable or they are blended with surfactants to make emulsions/dispersions.

Examples of suitable commercially available epoxy-based binders are:

- Bisphenol A type epoxy-based binders: D.E.R. 331 from Olin, D.E.R. 332 from Olin, D.E.R 337 from Olin, D.E.R. 669E from Olin, EPON Resin 1001F from Westlake (former Hexion), Araldite GY 776 from Huntsman Advanced Materials,

- Bisphenol F epoxy-based binders: Epikote 862 from Westlake (former Hexion), or D.E.R. 354 from Olin.

- Mixture of bisphenol A and bisphenol F: D.E.R. 352 from Olin, or Epikote 235 from Westlake (former Hexion).

- Solid type-1 epoxy resin dispersion in water e.g. Beckopox EP 2375w/60WA or Beckopox EP 2384w/57WA from Allnex, NPEW-261W55 or NPEW-292-53WH from NanYa, BE3570W55 from Chang Chun Plastics, EPI-REZ 3523-WH-53 or EPI-REZ 6520-W-53, EPI-REZ Resin 6521-WH-56 or EPI-REZ or 7520-WD-52 from Westlake (former Hexion).

- Liquid bisphenol based epoxy resin emulsion in water e.g. KEM-128-70 from Kukdo, EPI-REZ Resin 3510-W-60, EPI-REZ Resin 7510-W-60 and EPI-REZ Resin 3515-W-60 from Westlake (former Hexion).

Self-emulsifying epoxy-resins such as KEM-1200 from Kukdo, Beckopox EP 147w from Allnex, EPI-REZ resin WD-510 and EPI-REZ Resin WD-512 from Westlake (former Hexion).

The one or more epoxy-based binder forms 15 to 70 wt% of the total weight of component A, preferably 20 to 60 wt%, more preferably 20 to 50 wt%, for example 25 to 40 wt%. It is within the ambit of the invention for these to be a single epoxy based binder, or a mixture of more than one epoxy based binder, such as two or three or more epoxy-based binders.

Water

Component A comprises 20 to 60 wt% water, relative to the total weight of component A as a whole remembering that water may be added or derive from the WB epoxy binder. Preferably, water is present in an amount of 25 to 55 wt%, more preferably 30 to 50 wt% relative to the total weight of component A.

The primer composition typically comprises 15 to 60 wt% water relative to the total weight of the primer composition as a whole, preferably 20 to 50 wt%, such as 25 to 45 wt%. It will be appreciated that these wt% values include water that is added to the paint during manufacture as well as water contained in the other raw materials used in the composition, such as water contained in the dispersed or emulsified epoxy-based binder. The total amount of water included in the composition will to a large degree depend on the types and amounts of other raw materials used.

Component B

Component B comprises an amine based curing agent and at least one silane. It is a further requirement that component B comprises less than 5 wt% water, relative to the total weight of component B. Preferably, component B comprises less than 3wt%, more preferably less than 2.5 wt%, even more preferably less than 0.5 wt%, such as less than 0.1 wt% water, relative to the total weight of component B. Ideally, component B is essentially free of water.

Curing agent

Component B of the primer compositions of the invention comprises at least one curing agent. The curing agent is an amine based curing agent.

The curing agent is ideally a polyamine or modified polyamine. The curing agent may be a polyamide, amidoamine or ketimine. Ideally, the curing agent is not modified in any way to increase its compatibility with water. That is, no surfactants are added to the curing agent, and no hydrophilic structural segments like polyoxyalkylene segments are present in the molecular structure of the curing agent in an amount that enables the curing agent to form a solution or a stable emulsion in water. Thus, the curing agent in itself is not a hydrophilic modified curing agent.

Ideally, the curing agent is not a water-soluble or water-dilutable curing agent, i.e. it is preferably not soluble in or compatible with a mixture of 50 wt% water and 50 wt% of the curing agent, more preferably it is not soluble or compatible in a mixture with 30 wt% water and 70 wt% curing agent, even more preferably it is not soluble or compatible with a mixture of 20 wt% water and 80 wt% curing agent. Examples of incompatibility with water may be phase separation, crystallization/precipitation and formation of an unstable emulsion. Furthermore, it is preferable if the curing agent is not an aqueous solution or suspension.

Preferably, the curing agent is a polyamine comprising at least two amino groups. To obtain a crosslinked network the curing agent ideally contains at least three "reactive" hydrogen atoms. “Reactive” hydrogen atom refers to the hydrogen atom that is transferred from the nucleophile to the oxygen atom of the epoxide during the ring opening reaction. Curing active amine groups cannot therefore be tertiary. Tertiary amine containing compounds may however be added to the composition as curing accelerators or be present in the curing agent e.g as a part of a polymer or oligomer. The curing agent typically contains at least two curing reactive functional groups.

Suitable curing agents include ketimines, e.g. ketimines based on polyamines and methyl ethyl ketone. Curing agents comprising an amidoamine are also suitable, e.g. based on a fatty acid and ethyleneamines. Curing agent comprising a polyamide can be used, such as those based on a fatty acid dimer and ethylene amine. Curing agents comprising an aliphatic polyamine adduct can be used. It will be appreciated that there are countless proprietary amine curing agents on the market which the skilled person can use (although their exact structures is kept a secret by the owner).

Preferably, the curing agent is an amine based curing agent comprising a cyclic structure, meaning that it has a structure comprising at least one amine functional group and at least one cyclic group. In one particularly preferred embodiment, the amine based curing agent comprises a benzylamine motif, which has the structure shown below:

The benzylamine motif in the curing agent may be optionally substituted either on the ring, the methylene linker or the N atom although one active hydrogen must remain. Suitable substituents include Cl-15 alkyl groups, OH, O-Cl-4-alkyl, halogen, cyano, amine and alkyl amine groups (C1-4-N).

In one preferred embodiment the curing agent comprising the benzylamine motif is a Mannich reaction product of a phenol, an aldehyde and a primary diamine. These reaction products and curing agents derived from them are often termed Mannich bases. The phenol may be unsubstituted or substituted. Substituents may include Cl-15 alkyl or alkenylene groups, O-C1-C4 alkyl, halogen, cyano and alkyl amine groups. Preferably the phenol is unsubstituted or comprises a C15 alkyl chain. Phenols with a Cl 5 alkyl side chain of varying degree of unsaturation (saturated, mono-unsaturated, di-unsaturated, and tri-unsaturated) are obtained from cashew nut shell liquid and are called cardanol, Mannich reaction products of cardanol are called phenalkamines. The aldehyde is preferably formaldehyde. Non-limiting examples of primary diamine may be polyethylene amines such as ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA) or higher ethyleneamines. Alternatively, the primary diamine may be cycloaliphatic amines such as isophoronediamine, 1,3- bis(aminomethyl)cy clohexane, 1 ,4-bis(aminomethyl)cy clohexane, norbomanediamine or arylalkyl amines like l,2-bis(aminomethyl)benzene 1,3- bis(aminomethyl)benzene (MXDA) and l,4-bis(aminomethyl)benzene. Preferably the amine is l,3-bis(aminomethyl)benzene (MXDA).

In another embodiment the curing agent comprising the benzylamine motif is a reaction product of an arylalkyl amine and styrene. Suitable amines are 1,2- bis(aminomethyl)benzene, l,3-bis(aminomethyl)benzene (MXDA), and 1,4- bis(aminomethyl)benzene. The amine is preferably l,3-bis(aminomethyl)benzene (MXDA).

In another preferred embodiment, the curing agent is a polyamine curing agent comprising one or more benzylamine structures. More specifically, in this embodiment, the curing agent preferably comprises two or more repeating units, i.e. the curing agent is polymeric or oligomeric. Preferably the curing agent is a polyamine polymer that comprises a benzylamine structure on at least one end of the polyamine polymer chain. The polyamine polymer may comprise benzyl amine structures at both ends of the polymer chain. Each repeating unit may also comprise a benzylamine group. The benzylamine group may be substituted or unsubstituted.

In one preferred embodiment, the curing agent comprises at least two or more benzylamine structures.

In one particularly preferred embodiment the curing agent comprises a benzylated polyalkylene polyamine structure as described in WO2017/147138 Al. The benzylated polyalkylene polyamine structure preferably has a structure as shown below.

wherein R¹ is substituted or unsubstituted benzyl

R² is independently selected from R¹ or a hydrogen atom or a group selected from Ci to C 16 linear, cyclic or branched alkyl, alkenyl and alkylaryl groups

X, Y and Z are independently selected from C2 to C10 alkylene and cycloalkylene groups, preferably ethylene, propylene, butylene, hexylene, cyclohexyldimethylene and cyclohexalene. y is and integer from 1 to 7 z is an integer from 0-4.

Examples of suitable benzylated polyalkylene polyamine structures are benzylated polyethylene polyamines, benzylated polypropylene polyamines, benzylated polyethylene-polypropylene polyamines, and combinations thereof. Non-limiting examples of polyethylene polyamines include ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), and other higher polyethylene polyamines. Suitable polypropylene polyamines include, but are not limited to, propylene diamine (PDA), dipropylenetriamine (DPTA), tripropylenetetramine, and other higher polypropylene polyamines. Other polyalkylene polyamines include N-3 -aminopropyl ethylenediamine, N,N'-bis(3- aminopropyl) ethylenediamine, and N,N,N'-tris(3 -aminopropyl) ethylenediamine, N- 3-aminopropyl diethylenetriamine; N-3-aminopropyl-[N'-3-[N-3 aminopropyl]aminopropyl]di ethylenetriamine; N,N'-bis(3- aminopropyl)diethylenetriamine; N,N-bis(3-aminopropyl)diethylenetriamine; N,N,N'-tris(3-aminopropyl)di ethylenetri amine; N,N',N"-tris(3- aminopropyl)diethylenetriamine; N,N,N',N'-tetrakis(3- aminopropyl)diethylenetriamine; N,N-bis(3-aminopropyl)-[N'-3-[N-3- aminopropyl]aminopropyl]-[N'-3-aminopropyl]diethylenetriamine; and N-3- aminopropyl-[N'-3-[N-3-aminopropyl]aminopropyl]-[N'-3- aminopropy 1] di ethyl enetri amine .

The benzylated polyalkylene polyamine structures are typically prepared by a reductive amination of benzaldehyde, including both substituted and unsubstituted benzaldehydes with a polyalkylene polyamine. Examples of substituted benzaldehydes are benzaldehydes where the aromatic ring is substituted with one or more halogen atoms, C1-C4 alkyl, methoxy, ethoxy, amino, hydroxyl or cyano groups. Preferred benzaldehydes are benzaldehyde and vanillin.

The benzylated polyalkylene polyamine structure may be further reacted with for example Mannich bases as described in WO2017147138 Al or epoxyfunctional compounds to make epoxy-adducts.

In another embodiment, the curing agent is an amine epoxy adduct, such as an adduct made by reacting a bisphenol type epoxy resin with primary diamines, preferably the epoxy resin is a bisphenol A type. Preferably the bisphenol A epoxy resin has an EEW of less than 250 g/eq. Suitable primary diamines for the synthesis of the amine epoxy adduct may be ethyleneamines such as ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), and other higher polyethylene polyamines. Aliphatic primary diamines like 1,3-diaminopropane, 1,4- diaminobutane, 1,5-diaminopentane, l,5-diamino-2-methylpentane, 1,6- hexanediamine may also be used. Primary diamines comprising a cyclic structure, such as, 1,4-diaminocyclohexane, isophoronediamine (IPDA), 1,3- bis(aminomethyl)cyclohexane, 1 ,4-bis(aminomethyl)cy clohexane, 1,3- bis(aminomethyl)benzene (MXDA) and l,4-bis(aminomethyl)benzene may also be used. Preferably, the amine epoxy adduct curing agent comprises an amine with cyclic structure, and preferably has an average molecular weight of 500 g/mol to 3000 g/mol, more preferably 600 g/mol to 2000 g/mol.

The amine epoxy adduct is synthesized by letting the epoxy resin react with an excess of the primary diamines at 40 to 100 °C. The reaction may take place in a solvent like butanol or benzyl alcohol, preferably the solvent is benzyl alcohol.

The curing agent may be supplied as 100 wt% solids, or with reduced wt% solids together with a solvent, preferably a solvent that is compatible with waterborne paints, such as benzyl alcohol.

When accounting for components not contributing to cross-linking, like solvents, plasticisers and accelerators, the form of delivery or “as supplied” AHEW of the curing agent is obtained. The form of delivery or “as supplied” AHEW is commonly stated in the technical datasheet of commercially available curing agents. Thus, the amine-based curing agent preferably has a form of delivery AHEW of 40 to 300 g/eq, preferably 60 to 150 g/eq, most preferably the AHEW is 80 to 110 g/eq.

The viscosity of the amine-based curing agent may be up to 8000 mPas and is preferably below 1000 mPas, preferably 800 to 50 mPas, more preferably 700 to 60 mPas as measured according to ISO 2884-1 :2006 at 23 °C.

The amine based curing agent is preferably present in an amount of 3 to 80 wt%, more preferably 4 to 60 wt%, even more preferably 5 to 40 wt%, such as 8 to 30 wt%, relative to the total weight of component B.

Suitable commercially available curing agents are Gaskamine 240 from Mitsubishi Gas Chemical Company Inc., Ancamine 1618, Ancamine 2422 and Ancamine 2432, Ancamine 2519, Ancamine 2738, Ancamine 2739, Ancamine 2712M all from Evonik, and phenalkamines like NX-5594, GX-5135, GX-6027, NC-540, NC-541, NC-541LV, LITE 2001, LITE 2001LV and Lite 2002 all from Cardolite.

Silane

Component B comprises at least one silane. A silane may be present in component B or in both component A and component B. It is required that the silane is at least present in component B.

Silanes may improve the flexibility and cohesion of the primer as well as its adhesion to substrates and anti-corrosive performance, and are efficient thinners in suitable systems.

Silanes of use in the invention include oligomers of silanes and may have Mw in the range of less than 1500 g/mol.

Suitable silanes are of general formula (I) or (II)

(I) Y-R(4-z)SiXz wherein z is an integer from 1 to 3,

(II) Y-Ro-y^SiXy wherein y is an integer from 1 to 2, and where for both formula (I) and (II),

R is a hydrocarbylene group having 1 to 12 C atoms optionally containing an ether or amino linker,

R¹ is a hydrocarbyl group having 1 to 12 C atoms;

Y is a functional group bound to R that can react with the epoxy-based binder and/or the curing agent. Preferably Y is an isocyanate, epoxy, amino, hydroxy, carboxy, acrylate, or methacrylate group. The Y group can bind to any part of the chain R. It will be appreciated that where Y represents an epoxy group then R will possess at least two carbon atoms to allow formation of the epoxide ring system. The at least one silane present in component B is preferably an amino functional silane, i.e. wherein Y is an amino group. The amino group(s) are preferably NH2.

Each X independently represents a halogen group or an alkoxy group. It is especially preferred if X is an alkoxy group such as a Cl -6 alkoxy group, especially methoxy or ethoxy group. It is also especially preferred if there are two or three alkoxy groups present. Thus, z is ideally 2 or 3, especially 3.

Subscript y is preferably 2.

R¹ is preferably Cl-4 alkyl such as methyl. R is a hydrocarbon group having up to 12 carbon atoms.

By hydrocarbon is meant a group comprising C and H atoms only. It may comprise an alkylene chain or a combination of an alkylene chain and rings such as phenyl or cyclohexyl rings. The term "optionally containing an ether or amino linker" implies that the carbon chain can be interrupted by a -O- or -NH- group in the chain, e.g. to form a silane such as [3-(2,3 - epoxypropoxy)propyl]trimethoxysilane: EECOCElCEkOCEkCEkCEkS^OCEls It is preferred if the group Y does not bind to a carbon atom which is bound to such a linker -O- or -NH-.

R is preferably an unsubstituted (other than Y obviously), unbranched alkyl chain having 2 to 8 C atoms.

A preferred silane general formula is therefore of structure (III)

(III) Y'-R'(4-z)SiX'_Z' wherein z¹ is an integer from 2 to 3, R¹ is an un substituted, unbranched alkyl chain having 2 to 8 C atoms optionally containing an ether or amino linker, Y¹ is an amino or epoxy functional group bound to the R¹ group, and X¹ represents an alkoxy group.

Examples of such silanes are the many representatives of the products manufactured by Evonik Industries AG and marketed under the brand name of Dynasylan(R), the Silquest(R) silanes manufactured by Momentive, and the GENIOSIL(R) silanes manufactured by Wacker.

Specific examples include methacryloxypropyltrimethoxysilane (Dynasylan MEMO, Silquest A-174NT), 3 -mercaptopropyltri (m)ethoxy silane (Dynasylan MTMO or 3201; Silquest A- 189), 3-glycidoxypropyltrimethoxysilane (Dynasylan GLYMO, Silquest A- 187), 3 -glycidoxypropyltri ethoxy silane (Dynasylan GLYEO), tris(3 -trimethoxy silylpropyl) isocyanurate (Silquest Y- 11597), beta-(3,4- epoxycyclohexyl)ethyltrimethoxy silane (Silquest A- 186), gamma- isocyanatopropyltrimethoxysilane (Silquest A-Link 35, Geniosil GF40), (methacryloxymethyl)trimethoxysilane (Geniosil XL 33), (isocyanatomethyl)trimethoxysilane (Geniosil XL 43), 3- aminopropyltrimethoxy silane (Dynasylan AMMO; Silquest A-l 110), 3- aminopropyltri ethoxy silane (Dynasylan AMEO, Silquest A-l 100) orN-(2- aminoethyl)-3 -aminopropyltrimethoxy silane (Dynasylan DAMO, Silquest A-l 120) or N-(2-aminoethyl)-3 -aminopropyltri ethoxy silane, 3-[2-(2- aminoethylamino)ethylamino]propyltrimethoxysilane (Silquest A-l 130), bis[3- (trimethoxysilyl)propyl]amine (Silquest A-l 170), N-ethyl-3 -trimethoxy silyl-2- methylpropanamine (Silquest A-Link 15), N-phenyl-3-aminopropyltrimethoxysilane (Silquest Y-9669), 4-amino-3,3- dimethylbutyltrimethoxysilane (Silquest Y-l 1637), (N-cyclohexylaminomethyl)triethoxysilane (Geniosil XL 926), (N- phenylaminomethyl)trimethoxysilane (Geniosil XL 973), Deolink Epoxy TE and Deolink Amino TE (D.O.G Deutsche Oelfabrik) and mixtures thereof. The oligomeric epoxysilane, Coatosil MP 200 from Momentive may also be used in the composition.

Silanes suitable for formulating into component B include 3- aminopropyltri ethoxy silane, 3 -aminopropyltrimethoxysilane, N-(2-aminoethyl)-3- aminopropyltrimethoxy silane, N-(2-aminoethyl)-3 -aminopropyltri ethoxy silane, 3- aminopropylmethyldi ethoxy silane, N-(2-aminoethyl)-3- aminopropylmethyldimethoxy silane , and 3 -mercaptopropyltri (m)ethoxy silane.

The use of silanes 3 -aminopropyltrimethoxy silane and/or 3- aminopropyltriethoxysilane is especially preferred. A mixture of silanes might also be used.

The amount of silane present in component B may be 1.0 to 20 wt%, preferably 2.0 to 15 wt.%, relative to the total weight of component B.

Component A may also optionally comprise a silane. In this embodiment, the silane present in component A is different to the silane present in component B. The silane in component A may be reactive towards the amine functionality of the curing agent in component B, such as epoxy functional silanes and (meth)acrylic functional silanes. Preferably, the silane present in component A is an epoxy functional silane, i.e. wherein, in Formulas (I) or (II) above, Y is an epoxy group. The use of 3 -glycidoxypropyltri ethoxy silane (H2COCHCH2OCH2 CH2CH2Si(OCH2CH3)3 and/or 3-glycidoxypropyltrimtethoxysilane (H2COCHCH2OCH2CH2CH2 Si(OCH3)3), or the oligomeric epoxysilane Coatosil MP 200 is especially preferred.

The amount of silane(s) present in the primer composition as a whole may be 0.1 to 15 wt%, preferably 0.25 to 10 wt.%, more preferably 0.5 to 5.0 wt%, relative to the total weight of the primer composition as a whole.

It is important for the present invention that the silane is formulated in a component that has no water. This is preferably component B. The silane is preferably an aminosilane. The silane should not react with the curing agent but is preferably reactive towards the epoxy resin of component A.

Other Components of the primer composition:

The primer composition may comprise a number of other components which may be formulated as part of component A and/or B.

Reactive diluents

The primer composition may further comprise a reactive diluent. The reactive diluent may be any reactive compound that will contribute to reduced viscosity of the primer composition or one of its constituents, i.e a binder or a resin. The reactive diluent is typically added to component A and may be an acrylic ester compound or an epoxy compound. Acrylic esters may be added with the purpose of both acting as a diluent and as a curing accelerator.

Examples of suitable acrylic esters are 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate and mixtures thereof.

Examples of suitable epoxy functional reactive diluents include phenyl glycidyl ether, alkyl glycidyl ether (number of carbon atoms in alkyl group: 1 to 16), glycidyl ester of neodecanoic acid (R1 R2 R3C-COO-Gly, where R1 R2 R3 are alkyl groups such as C8 to CIO alkyl and Gly is a glycidyl group), olefin epoxide (CH3-(CH2)n-Gly, wherein n=l l to 13, Gly: glycidyl group), 1,4-butanediol diglycidyl ether (Gly-O-(CH2)4-O-Gly), 1,6-hexanediol di glycidyl ether (Gly-O- (CH2)6-O-Gly), neopentyl glycol diglycidyl ether (Gly-O-CH2-C(CH3)2-CH2-O- Gly), trimethylolpropane triglycidyl ether (CH3-CH2-C(CH2-O-Gly)3), and Cl-20- alkylphenyl glycidyl ether (preferably Cl -5 alkylphenylglycidyl ether), e.g., methylphenyl glycidyl ether, ethylphenyl glycidyl ether, propylphenyl glycidyl ether and para tertiary butyl phenyl glycidyl ether (p-TBPGE), reaction products of epichlorohydrin and an oil obtained from the shells of cashew nuts.

In one embodiment the reactive diluent is reaction products of epichlorohydrin and cardanol, like for example Cardolite NC-513 from Cardolite.

In another particularly preferred embodiment the reactive diluents are aliphatic reactive diluents. The aliphatic reactive diluents are preferably formed from the reaction of a compound comprising at least one aliphatic epoxide functionality with an aliphatic alcohol, such as dodecyl and tetradecyl glycidyl ethers, or an aliphatic polyol such as 1,6-hexanediol diglycidyl ether or 1,4- butanediol diglycidyl ether. Aliphatic glycidyl ethers of chain length 8 to 14 are preferred. Aliphatic reactive diluents may contribute to the flexibility of the primer film.

The above reactive diluents can be used singly or in combination of two or more diluents.

The reactive diluent, if present, is preferably present in an amount of 0.1 to 30 wt% preferably 0.2 to 20 wt%, more preferred 0.5 to 10 wt% of the primer composition.

By adding the reactive diluent in the above amount, the viscosity of the primer composition and/or some of its constituents may be reduced and film formation properties may be improved.

Preferably the viscosity of the reactive diluent is <100 cp, preferably <50 cP, preferably <30 cP, most preferably viscosity <20 cP.

The epoxy equivalent weight (EEW) of the reactive diluents is preferably 50 to 500 g/eq, more preferred 100 to 400 g/eq, most preferred 100 to 300 g/eq.

The reactive diluent is preferably present in Component A. Accelerators

The primer composition may further comprise a curing accelerator. A curing accelerator will increase the curing rate of the composition and is an optional feature. For amine cured epoxy compositions like the one of the present invention, phenolic compounds, salts of strong acids, tertiary amine compounds, and acrylic esters as described in the section on reactive diluents may be employed as accelerators.

Phenolic compounds that may be suitable accelerators are compounds such as phenols, bisphenols, alkyl phenols including cardanol, and benzoic acid derivatives such as salicylic acid. Salts of strong acids that may be suitable as accelerators include tritiate salts of the metals in group 2 of the periodic table such as Mg and Ca. Tertiary amine compounds suitable as accelerators are 3- aminopropyldimethylamine, benzyldimethylamine, l,4-diazabicyclo[2.2.2]octane, l,8-diazabicyclo[5.4.0]undec-7-ene, dimethylethanolamine, diethylethanolamine, triethanolamine, and 2,4,6-tris(dimethylaminomethyl)phenol (Ancamine K54 from Evonik).

Phenolic accelerators may be present in component A or component B, while the tertiary amine based accelerators may be present in component B of the primer composition.

The accelerator is typically added in an amount of 0. l-5wt% based on the total composition, such as 0.2-2.5wt%.

Hydrocarbon resin

The primer composition of the invention optionally comprises a hydrocarbon resin. A wide range of hydrocarbon resins are suitable for including in the primer composition. Preferably the hydrocarbon resin is a petroleum resin.

Examples of petroleum resins suitable in the present invention include an aromatic petroleum resin obtained by polymerizing a C9 fraction (e.g. styrene derivatives such as alpha methylstyrene, o, m, p-cresol, indene, methyl indene, cumene, naphthalene or vinyltoluene) obtained from a heavy oil that is produced as a by-product by naphtha cracking, an aliphatic petroleum resin obtained by polymerizing a C5 fraction such as 1,3 -pentadiene or isoprene, 2-methyl-2-butene, cyclopentadiene, dicyclopentadiene or cyclopentene. Also employable in the invention are a copolymer-based petroleum resin obtained by copolymerizing the C9 fraction and the C5 fraction, an aliphatic petroleum resin wherein a part of a conjugated diene of the C5 fraction such as cyclopentadiene or 1,3 -pentadiene is cyclic-polymerized, a resin obtained by hydrogenating the aromatic petroleum resin, and an alicyclic petroleum resin obtained by polymerizing dicyclopentadiene.

Mixtures of diaryl and triaryl compounds obtained from reaction of C9 blends under catalytic conditions are also possible to utilize.

Other examples of hydrocarbon resins are indene-coumarone resins, and xylene-formaldehyde resins.

Preferably, the hydrocarbon resin does not contain any OH-functionality and has a viscosity of 50 to 10000 mPas.

The primer composition of the present invention preferably comprises 0-15 wt%, hydrocarbon resin, such as 1-7 wt%, based on the total weight of the composition.

The hydrocarbon resin may be present either in component A or in component B of the primer composition, usually it is present in component B of the primer composition.

Component B may comprise 10 to 30 wt% of the hydrocarbon resin, such as 13 to 25 wt%.

Examples of suitable commercially available hydrocarbon resins may be Novares TL 10, Novares L 100, Novares L 100 W from Rutgers, and Epodil LV5 from Evonik.

Other binders

The primer composition of the present invention might optionally comprise other binders than the epoxy binders, amine based curing agents, and the hydrocarbon resins described above to adjust the properties of the primer composition, such as mechanical properties, UV-stability, intercoat adhesion and film formation properties. Such binders might be thermoplastic binders that forms films by physical drying, and some of the resins might also cross-link by reaction with oxygen and/or moisture from the atmosphere.

Such binders might comprise of acrylic (co)polymers, vinylic (co)polymers, polyester binders, including alkyds and alkyd modified epoxy resins e.g. epoxy esters, and polysiloxanes. It is appreciated that such resins also might optionally comprise of reactive groups that are capable of reacting with either the epoxy groups found in the epoxy binders or the amine groups found in the amine based curing agents described in the sections above.

The thermoplastic binders might be dissolved in an organic solvent or might be suspended in an aqueous medium in the form of an emulsion or a dispersion.

Non-limiting examples of suitable commercially available resins may be Elvax 40W from Dow, Laroflex MP 15, Laroflex MP 25, Laroflex MP 35, Laroflex MP 45 and Laroflex MP 60 from BASF, DAOTAN® STW 6434/40WA from Allnex, Eposil 5500, VeoVa 9, VeoVa 10 and VeoVa EH from Hexion, PC-Mull GR 100, EPS 545 and EPS 541, EPS 2458, EPS 2512, EPS 2615, EPS 4216, EPS 4402, EPS 6264, from EPS, Tego Phobe 1401, Tego Phobe 1409, Tego Phobe 1500N, Tego Phobe 1659, Tego Phobe 6010, Tego Phobe 6510, Tego Phobe 6600 and Sivo 214 from Evonik

Hollow spherical filler particles

The primer composition of the present invention may comprise hollow spherical filler particles. The filler particles may be inorganic such as ceramic, metal oxide or glass, or organic such as polymeric spheres based on e.g. poly(meth)acrylate, polyvinyl or polyvinylidene. Suitable hollow, spherical, filler particles are commercially available. Examples of commercially available inorganic, spherical filler particles include Glass Bubbles S28HS, Glass Bubbles S38HS, Fillite Cenosphere, Poraver (expanded glass), Eccospheres, Q-Cel, Sphericel, Omega Shperes, (availale from e.g. 3M, Omya, Poraver, Trelleborg, Potters, Omega, SMC minerals) and hollow glass spheres from Hollowlite. Examples of commercially available organic spherical filler particles are the Dualite® grades E030, E055, E065-135D, E130-055D, E130-095D, E130-105D, E130-040D, E035-FR and E135-025D all from Chase Corporation. The hollow, spherical particles are an optional component of the primer composition. The hollow filler particles will aid in increasing the volume% solids of the formulation when used in place of conventional mineral based fillers (described in the next section).

The spherical, filler particles are hollow. This means the particles have a void or cavity in their centres. This void or empty space is filled with gas, preferably air. Preferred spherical, filler particles for use in the present invention are substantially hollow. Thus, preferably the volume of the void or cavity is at least 70 vol% and more preferably at least 80 vol% of the total volume of the particles. Preferably the hollow, spherical, filler particles have as low a density as practicable, e.g. the density of the hollow, spherical, filler particles might be 0.1-1 g/cm³, more preferably 0.2-0.8 g/cm³, and still more preferably 0.2-0.4 g/cm³, e.g. as specified on the technical specification provided by suppliers. This reflects the fact that the particles are hollow rather than solid. Lower density particles are advantageous because they will contribute positively to the volume percentage of solids at a much lower weight percentage loading than conventional mineral based fillers.

Preferably the hollow, spherical, filler particles present in the primer compositions of the present invention have a crush strength of at least 3000 psi (90% survival by volume), as specified by the supplier in the technical datasheet (Nitrogen Isostatic Crush Strength test). This is beneficial as it means that the filler particles are not crushed during application and processing and thus maintain their ability to provide a low density primer composition. It is also advantageous that the filler particles do not change shape and/or size during processing, so they can pack tightly and achieve a high build in the final primers formed.

The hollow, spherical, filler particles present in the primer compositions of the present invention are preferably inorganic and comprise and more preferably consist of glass, ceramic or metal oxide. More preferably the hollow, inorganic, spherical, filler particles present in the primer compositions of the present invention comprise and still more preferably consist of glass. This is because glass particles provide a good balance of crush strength, hardness and density. Optionally the hollow, inorganic, spherical, filler particles present in the primer compositions of the present invention may be surface treated. Some examples of surface treatment include treatment to alter the hydrophobicity of the surface, to improve compatibility with the binder and/or to facilitate chemical incorporation into the binder.

The hollow, inorganic, filler particles present in the primer compositions of the invention are substantially spherical and more preferably spherical. This is advantageous as it allows the filler particles to pack more closely together in the primer compositions of the invention. Preferably the hollow, inorganic, filler particles have a mean diameter (d50) of 1 to 100 pm, more preferably 1 to 80 pm and still more preferably 10 to 50 pm, as determined by ISO 13320:2009 using a Malvern Mastersizer 2000. These particle sizes are preferred to ensure that the primer has adequate visual appearance, anticorrosive properties at low dry film thickness, and viscosity.

Preferred primer compositions of the present invention comprise 1.0 to 10 wt%, more preferably 1.5 to 7.5 wt% and still more preferably 2.0 to 5.0 wt% hollow, inorganic, spherical, filler particles, based on the total weight of the composition. The hollow, inorganic, spherical filler particles are generally present in component B of the primer composition.

Fillers and pigments

The primer composition optionally comprises fillers and colour pigments.

The fillers comprise organic and inorganic fillers, the inorganic fillers may be naturally occurring, i.e. mined or of synthetic origin i.e. precipitated, and may or may not be surface treated.

Suitable types of inorganic fillers may be selected from the following groups of minerals; silicates, phyllosilicates, silicas, carbonates, barytes, metal oxides, metals, phosphates, halides, sulfides and sulfates. Organic fillers may comprise organic polymers or polymer blends, graphite, graphene, graphene oxide, fullerenes, carbon nanotubes, carbon fibers as well as organic polymer particles, e.g. core-shell particles containing an organic compound(s) such as a dye, resin and/or an organic liquid.

Non-limiting examples of fillers that can be used in the primer composition according to the present invention are nepheline syenite, talcum, plastorite, chlorites, chrysolite, mica, pyrophyllite, feldspars, bentones, kaolins, mica/muscovite, clays, wollastonite, quartz, christobalite, glass flakes, glass fibers, fumed silica, calcium silicate, pumice, diatomaceous earth, calcium carbonate, magnesium carbonate, calcium sulfate, dolomite, barium sulfate, iron oxide, micaceous iron oxide, zinc oxide, aluminium oxide, aluminium hydroxide, aluminium flakes, zinc flakes, and solid silicone resins, which are generally condensed branched polysiloxanes. Some fillers such as fumed silica and clays may have a thickening effect on the primer composition. Inorganic core-shell particles containing an organic compound(s) such as a dye, resin and/or an organic liquid may also be used.

An example of a preferred filler is wollastonite. The wollastonite may or may not be surface treated. Examples of commercially available wollastonite fillers are Nyad® M1250, Nyad® M325, Nyad® M400, Nyad® 325, Nyad® 400, Nyad® MG, 10 AS Wollastocoat®, 10 ES Wollastocoat®, M400 Wollastocoat®, M9000 Wollastocoat® from Imerys, and Tremin® 283, Tremin® 939 from Quartzwerke group.

The pigment(s) may be inorganic pigments, organic pigments or a mixture thereof. The pigments may be surface treated.

Representative examples of pigments include black iron oxide, red iron oxide, yellow iron oxide, titanium dioxide, zinc oxide, carbon black, graphite, red molybdate, yellow molybdate, zinc sulfide, antimony oxide, sodium aluminium sulfosilicates, quinacridones, phthalocyanine blue, phthalocyanine green, indanthrone blue, cobalt aluminium oxide, carbazoledioxazine, isoindoline orange, bis-acetoaceto-tolidiole, benzimidazolone, quinaphthalone yellow, isoindoline yellow, tetrachloroisoindolinone, and quinophthalone yellow, metallic flake materials (e.g. aluminium flakes). Preferred pigments are black iron oxide, red iron oxide, yellow iron oxide and titanium dioxide. In one preferred embodiment the titanium dioxide is surface treaded with a silicone compound, a zirconium compound, an aluminium compound or a zinc compound.

Pigments and fillers may be added to the paint composition in the form of a powder or as a slurry or concentrate.

The amount of the at least one filler or pigment, including anticorrosive pigments, is preferably in the range 0.05 to 50 wt%, preferably in the range 1 to 45 wt% more preferably 5 to 40 wt% and still more preferably 10 to 35 wt%, based on the total weight of the primer composition.

The pigments and fillers can be added to component A or B and often both.

Anticorrosive pigments

Anticorrosive pigments and/or additives may be included in the primer composition to improve its anticorrosive performance. The types of anticorrosive pigments and additives are not specifically limited and any suitable anticorrosive pigments and additives may be used. The anti-corrosive pigments may be based on borates, borosilicates, phosphates, orthophosphates, polyphosphates, phosphosilicates, silicates combined with a metal or metal cation such as zinc, aluminium, molybdenium, calcium, strontium, aluminium magnesium, and barium, e.g. zinc or calcium phosphate. The anti-corrosive pigments may be modified, e.g. surface modified, and/or contain complex ions and chelates.

Non-limiting examples of suitable anti-corrosive additives may be imidazoles (in pure form or contained in a polymer or resin matrix) polymers and other organic substances such as C12-14-(tert)-alkylamines, (2-benzothiazolylthio)- butanedioic acid, 4-oxo-4-p-tolylbutyric acid, adduct with 4-ethylmorpholine, (2- benzothiazolylthio) butanedioic acid, poly(3- ammoniumpropylethoxysiloxane)dodecanoate, ammonium benzoate, and morpholine.

Examples of suitable commercially available anticorrosive pigments and additives may be: Halox 520, Halox 570, Halox 630, Halox 350, Halox 430, Halox 700, Halox BW-11. Halox BW-191, Halox CW-314, Halox CW-491, Halox CZ- 170, Halox SW-111, Halox SZP-391, Halox SZP-395, Halox Z-Plex 111, Haloz Z- Plex 250 and Halox Z-Plex 750 from Halox, Habicor CS, Habicor Si, Habicor ZS, Habicor ZA, Habicor ZN, Habicor ZO, Habicor ZM, Habicor AZ, Habicor SP, Habicor CP4295, Habicor Habicor ZP3850, Habicor ZP3860, Habicor 1000 and Habicor 1001 from Habicor and AX1 from Hexigone.

The primer composition may comprise of 0 to 15 wt%, e.g. 0.1 to 10 wt% of anticorrosive pigments/additives The primer composition preferably comprises zinc phosphate and/or calcium phosphate at a loading of between 0.5 and 10 wt%. Additives

The primer composition of the present invention optionally comprises one or more additives. Examples of additives that may be present in the primer composition of the invention include, rheology modifiers such as thixotropic agents, thickening agents and anti-settling agents, dispersing agents, wetting agents, coalescing additives, surfactants, surface active additives such as surface tension reduction additives, defoamers, plasticizers, flash rust inhibitors, in can corrosion inhibitors and biocides. Suitable additives are not necessarily limited to additives developed and sold for use in paint. Additives developed and sold for use in for instance adhesives, building materials, plastics/resins, drilling fluids, paper coatings and pigment concentrates may be used if compatible with the primer composition. As the efficiency of any additive used in waterborne primer compositions may, to a great extent, be influenced by the other raw materials and additives contained therein, it is important that suitable types and concentrations of additives are determined by testing. In many cases it may be necessary and/or useful to add several different additives of any given type, i.e. two or more defoamers or two or more rheology modifiers, to achieve the desired properties/efficiency.

Defoamers and air release additives, hereby just referred to as defoamers, are commonly used in waterborne paints due to its comparably higher concentration of surfactants and high surface tension relative to solvent borne and solvent free paints. The type of defoamer is not specifically limited and any suitable type can be used. Common defoamers can be divided into mineral oil defoamers, silicon defoamers and polymer defoamers. Commercially available defoamers often contain a mixture of these types, often in combination with solvents and solid particles. Non-limiting examples of defoamers that can be used may be Byk-011, Byk-012, Byk-014, Byk- 015, Byk-016, byk-017, Byk-018, Byk-019, Byk-021, Byk-022, Byk-023, Byk-024, Byk-025, Byk-028, Byk-035, Byk-037, Byk-038, Byk-039, Byk-044, Byk-051N, Byk-052N, Byk-053N, Byk-054, Byk-055, Byk-057, Byk-070, Byk-072, Byk-077, Byk-081, Byk-085, Byk-088, Byk-092, Byk-093, Byk-094, Byk-141, Byk-1610, Byk-1611, Byk-1615, Byk-1616, Byk-1617, Byk-1630, Byk-1640, Byk-1650, Byk- 1707, Byk-1709, Byk-1710, Byk-1711, Byk-1719, Byk-1723, Byk-1724, Byk-1730, Byk-1740, Byk-1751, Byk-1752, Byk-1758, Byk-1759, Byk-1760, Byk-1770, Byk- 1780, Byk-1781, Byk-1785, Byk-1786, Byk-1788, Byk-1789, Byk-1790, Byk-1791, Byk-1794, Byk-1795, Byk-1796, Byk-1797, Byk-1799, Byk-A 515, Byk-A 525, Byk-530, Byk-535, Byk-A 550, Byk-A 555 and Byk-A 560 from BYK, Tego Airex 901 W, Tego Airex 901 W N, Tego Airex 902 W, Tego Airex 902 W N, Tego Airex 904 W, Tego Airex 904 W N, Airase 4500, Airase 4655, Airase 5355, Airase 5655, Airase 8070, Surfonyl 104, Surfonyl 107L, Surfonyl 420, Tego foamex 3062, Tego Foamex 8050, Tego Foamex 843, Tego Foamex 844, Tego Foamex 845 Tego Foamex 883, Tego Foamex 1488, Tego Foamex 810, Tego Foamex 811, Tego Foamex 812, Tego Foamex815, Tego Foamex822, Tego Foamex 823 and Tego Foamex 825 from Evonik. Especially preferred defoamers is Byk-011 and Byk-022.

Flash rust and in-can rust preventative additives may be used to for instance prevent in-can rusting and the formation of flash-rust on metal substrates. The types of in-can rust preventatives and flash-rust inhibitors is not specifically limited and any suitable in-can rust preventatives and flash-rust inhibitors can be used. Common flash-rust inhibitors and in-can rust preventatives include borates such as sodium tetraborate, nitrites such as sodium nitrite, benzoates such as ammonium benzoate, benzotriazoles, phosphates such as dipotassium hydrogen orthophosphate, and alcohols such as 2-dimethylaminoethanol. Non-limiting examples of suitable commercially available products may be Halox Flash-X 150, Halox Flash-X 330, Lopon DK, Lopon DV from Halox.

Non-limiting examples of a preferred flash rust and in-can rust preventatives may be sodium nitrate and ammonium benzoate, or a combination thereof.

Biocides may be used to for instance prevent the in-can growth of bacteria and fungi. The type of biocide is not specifically limited and any suitable biocide can be used. Non-limiting examples of suitable in-can preservatives may be biocides based on one or several of methylchloroisothiazolinone (CIT), methylisothiazolinone (MIT) and benzisothiazolinone (BIT). Biocides described for layer (II) may optionally be used in the primer composition. Moreover, the in-can preservatives described above may optionally be used in the antifouling coating composition that provides layer (II). Surface-active additives may be added to for instance adjust the surface tension of the primer composition either at the primer/ substrate interface or primer/antifouling coating interface, mainly to prevent surface defects such as bad substrate wetting, cratering, floating and formation of Benard cells, reduce dirt pickup, adjust surface slip and to improve levelling and intercoat adhesion in coating systems. The type of surface-active additive is not specifically limited and any suitable surface-active additive can be used. Many surface-active additives are based on silicone surfactants like polyether modified polysiloxanes, organic polymers like polyacrylates, low molecular organic surfactants and fluoro-surfactants. Nonlimiting examples of suitable commercially available surface-active additives may be Byk-301, Byk-302, Byk-326, Byk-327, Byk-332, Byk-333, Byk-342, Byk-345, Byk-346, Byk-347, Byk-348, Byk-349, Byk-375, Byk-381, Byk-3400, Byk-3410, Byk-3420, Byk-3450, Byk-3451, Byk-3455, Byk-3456, Byk-3480, Byk-3481, Byk- 3499, Byk-3560, Byk-3565, Byk-3566, Byk-3751, Byk-3752, Byk-3753, Byk-3754, Byk-3760, Byk-3764, Byk-9890, Byk-DYNWET 800, Byk-Silclean 3720, Byketol- AQ, Byketol-PC, Byketol-WA, NanoByk-3603, NanoByk-3620, NanoByk-3650, NanoByk-3652.

A rheology modifier may be employed to adjust the rheological profile of the paint as to prevent settling and floating issues, thus extending the shelf-life of the paint, as well as to adjust flow and to improve sag resistance, workability, application properties and the stabilization of pigment and extender particles. The type of rheological modifier is not specifically limited and any suitable rheological modifier can be used but should be chosen based on which properties need to be improved and based on compatibility with the rest of the formulation. Non-limiting examples of suitable rheological modifiers may be cellulosic thickeners, xanthan gum, guar gum, organically modified clays such as bentonite, hectorite and attapulgite clays, unmodified clays, organic wax thixotropes based on castor oil and castor oil derivatives, amide waxes, rheology modifiers based on an acrylic, urea, modified urea, polyurethane, amide or polyamide backbone, and fumed silica. The active constituents of the rheological modifier may be modified with functional groups such as for instance polyether and alcohol groups, which is especially true for many of the associative types of rheological modifiers, or surface treated with for instance silanes which is common with fumed silica. Non-limiting examples of commercially available rheology modifiers may be TS-610, TS-530, EH-5, H-5, and M-5 from Cabot and Aerosil® R972, Aerosil® R974, Aerosil® R976, Aerosil® R104, Aerosil® 200, Aerosil® 300, Aerosil® R202, Aerosil® R208, Aerosil® R805, Aerosil® R812, Aerosil® 816, Aerosil® R7200, Aerosil® R8200, Aerosil® R9200, Aerosil® R711 from Evonik, Laponite SL 25, Claytone-3, Optigel CK, Rheobyk-420, Rheobyk 425, Rheobyk-D 410, Rheobyk-D 420, Rheobyk-425, Rheobyk-440, Rheobyk-M 2600 VF, Rheobyk-H 3300 VF, Rheobyk-H 6500 VF, Rheobyk 7420 ES/ET/CA, Rheobyk-7600, Rheobyk-7610 form BYK, Bentone SD2 and Bentone LT from Elementis, Exilva from Borregard, Crayvallac ultra and Crayvallac LV from Arkema and Borchigel 0621 from Borchers. Preferably the rheology modifier comprises a micronized amide wax and/or a fumed silica and/or a clay. Preferably the rheology modifier is present in the composition of the invention in an amount of 0-10 wt%, more preferably 0.1-6 wt% and still more preferably 0.1- 3.0 wt%, based on the total weight of the composition.

Wetting and dispersing agents may be added to the paint composition to for instance facilitate dispersion and wetting of the pigment and filler particles, thus making it easier to break up agglomerates during production, preventing reflocculation and settling in wet paint as well as formation of Benard cells in curing paint, reducing the paints viscosity and increasing its colour strength and colour stability. The wetting and dispersing agents may be non-ionic, cationic, anionic or comprise a mixture of the beforementioned. Furthermore, the wetting and dispersing agent may consist of polymers, or non-polymeric organic molecules or a mixture thereof. Preferably the wetting and dispersing agent comprises a polymeric compound. The type of wetting and dispersing agent is not specifically limited and any suitable wetting and dispersing agent can be used. Non-limiting examples of suitable types of wetting and dispersing agents may be fatty acids, lecithins, polysorbates, polyacrylamides, polyethercarboxylates, polycarboxylates, polyalkylene glycols, polyethers, polyacrylates, alkylolamino amides, polymeric phosphoric acid esters, polyalkylamines. Non-limiting examples of commercially available wetting and dispersing agent may be Anti-Terra-250, Byk-P-104, Byk-153, Byk-154, Disperbyk-102, Disperbyk-106, Disperbyk-109, Disperbyk-142, Disperbyk-161, Disperbyk-180, Disperbyk-182, Disperbyk-184, Disperbyk-185, Disperbyk-187, Disperbyk-190, Disperbyk-191, Disperbyk-192, disperbyk-193, Disperbyk-194 N, Disperbyk-199, Disperbyk-2000, Disperbyk-2010, Disperbyk- 2012, disperbyk-2014, Disperbyk-2015, Disperbyk-2018, Disperbyk-2019, Disperbyk 2055, Disperbyk-2059, Disperbyk-2070, Disperbyk 2080, Disperbyk- 2152 from BYK.

All these components can be formulated as part of component A or B or both.

Solvents

The primer composition of the present invention is a waterborne composition, i.e. one comprising water as the main solvent.

The primer composition typically comprises at least 15 wt% water, relative to the total weight of the composition as a whole. Preferably, the composition primer comprises 15 to 60 wt% water, more preferably 20 to 50 wt%, such as 25 to 45 wt%, relative to the total weight of the composition as a whole.

Organic solvents are typically also present in the composition, either in one component or in both component A and B. It is preferred if component A is organic solvent free. Any organic solvent is preferably present in component B.

Organic solvents are typically added to a waterborne primer composition to improve freeze-thaw stability and open time, to reduce surface tension and viscosity, and to facilitate film formation. The type of solvent is not specifically limited and any suitable solvent can be used. Suitable solvents may be, but are not limited to, aromatic hydrocarbons, ketones, esters, alcohols, glycol ethers, ethers and polyethers.

Examples of solvents that may be suitable for use in the composition include toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, methyl isoamyl ketone, ethyl acetate, butyl acetate, 2,2,4-trimethyl-l,3- pentanediol diisobutyrate (Texanol (TM)), ethanol, n-propanol, isopropanol, n- butanol, isobutanol, sec-butanol, tert-butanol, diacetone alcohol, benzyl alcohol, propylene glycol monomethyl ether, propylene glycol propyl ether, propylene glycol n-butyl ether, dipropylene glycol methyl ether, dipropylene glycol n-butyl ether, propylene glycol phenyl ether, tripropylene glycol n-butyl ether, ethylene glycol propyl ether and ethylene glycol butyl ether.

Of the above mentioned solvents, solvents capable of aiding the film formation of a waterborne primer composition are especially preferred. Such solvents are often called coalescing agents or film-forming agents.

In a waterborne primer composition, the applied wet product contains a binder that is dispersed or emulsified in water, as opposed to a solvent borne composition in which the binder normally is dissolved in the solvent when the paint is applied. For a waterborne epoxy primer composition to form a continuous coating film, the epoxy resin based binder dispersion particles or emulsion droplets must coalesce and flow together with the amine based curing agent. Coalescing additives or coalescing agents aid this process during drying of the primer film.

Examples of suitable coalescing agents may be 2,2,4-trimethyl-l,3- pentanediol diisobutyrate (Texanol (TM)), benzyl alcohol, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, propylene glycol phenyl ether, tripropylene glycol n-butyl ether, and diacetone alcohol.

An example of a preferred solvent is benzyl alcohol. Benzyl alcohol may be present alone or in combination with glycol ethers such as, propylene glycol n-butyl ether and dipropylene glycol n-butyl ether.

The primer composition as a whole may comprise 0 to 15 wt% organic solvents, preferably 1 to 10 wt%, most preferred 3 to 9 wt%.

Component B preferably comprises i) 5 to 40 wt% amine based curing agent; ii) 0.25 to 10 wt% silane; and iii) 10 to 30 wt% hydrocarbon resin.

Primer Composition Properties

Preferably the primer composition has a solids content of 40 to 90 wt%, such as 50 to 80 wt%, such as 55 to 70 wt%.

Preferably the primer composition has a volume solids of 30 to 80 vol%, such as 40 to 75 vol%, such as 45 to 70 vol%. Preferably the primer composition has a content of volatile organic compounds (VOC) of less than 120 g/L, more preferably less than 100 g/L. VOC content can be calculated (ASTM D5201 - 05a(2020), or measured (US EPA method 24 or ISO 11890-1).

Preferably the primer composition has a pigment volume concentration (PVC) of 20 to 50%, such as 30 to 45%.

Preferably the primer composition has a critical pigment volume concentration (CPVC) of 50 to 90%, such as 60 to 80%.

The ratio of the sum of epoxy equivalents of the reactive components of Component A to the sum of active hydrogen equivalents of component B of the present invention is preferably in the range of 70: 100 to 130: 100, more preferably 80: 100 to 120: 100.

It is preferable that the two components of the primer composition are formulated such that an even mixing ratio by volume is achieved.

It is preferred if the two components are mixed in a volume ratio of 1 : 1 to 5 : 1 component A to component B, such as 1.5 : 1 to 3 : 1.

It is preferred if the two components are mixed in a weight ratio of 1 : 1 to 8: 1 component A to component B, such as 2: 1 to 5 : 1.

Layer (II)

The antifouling coating system of the invention comprises a layer (II) which is an antifouling coating layer. Layer (II) comprises, such as consist of, an aqueous antifouling coating composition comprising a) a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer and b) a rosin or rosin derivative.

Polymeric binder

The coating composition of the present invention comprises a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer. The polymeric binder as defined above will herein be referred to as the “polymeric binder”. Examples of suitable ethylenically unsaturated monomers are (meth)acrylic acid, (meth)acrylic acid esters, (meth)acrylic acid amide, vinyl chloride, vinyl ester, vinyl acetate, vinyl propionatemaleic acid, itaconic acid, vinyl alcohol, styrene, a- m ethyl styrene, alkyl vinyl ether, vinyl pyrrolidone, N-vinyl caprolactame, N- methyl-N-vinylacetamide and (meth)acrylonitrile.

Preferably the ethylenically unsaturated monomer is selected from (meth)acrylic acid, (meth)acrylic acid esters, (meth)acrylic acid amide and vinyl ester such as vinyl acetate and vinyl neodecanoate.

In a particularly preferred embodiment, the ethylenically unsaturated monomer is selected from (meth)acrylic acid and (meth)acrylic acid esters.

Examples of the (meth)acrylic acid ester monomers include: alkylate or cycloalkyl ester of (meth)acrylic acid having 1 to 18 carbon atoms such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and cyclohexyl (meth)acrylate; alkoxy alkyl ester of (meth)acrylic acid having 2 to 18 carbon atoms such as methoxybutyl (meth)acrylate, methoxyethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, and ethoxybutyl (meth)acrylate; dialkylaminoalkyl ester of (meth)acrylic acid such as dimethylaminoethyl (meth)acrylate, 2-(diethylamino)ethyl (meth)acrylate, 2-(diisopropylamino)ethyl (meth)acrylate, 2-(tert-butylamino)ethyl (meth)acrylate, 4-dimethylaminobutyl (meth)acrylate and dimethylaminopropyl (meth)acrylate; hydroxy alkyl ester of (meth)acrylic acid such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3 -hydroxypropyl (meth)acrylate, 2- hydroxy-1 -methylethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and hydroxyisobutyl (meth)acrylate; glycidyl (meth)acrylate, (2,2-dimethyl-l,3-dioxolan-4-yl)methyl (meth)acrylate;

(meth)acrylic acid ester monomers comprising cyclic amines such as (meth)acryloyl-2-pyrrolidone; (meth)acrylic acid ester monomers comprising polysiloxane groups such as monomethacryloxypropyl terminated polydimethylsiloxane, such as a- methacryloyloxypropyl-o-butyl polydimethylsiloxane, a-methacryloyloxypropyl-o- trimethyl silyl polydimethylsiloxane, a-methacryloyloxyethyl-o-trimethylsilyl polydimethylsiloxane, a-acryloyloxypropyl-o-butyl polydimethylsiloxane, a- acryloyloxypropyl-o-trimethylsilyl polydimethylsiloxane, a-acryloyloxyethyl-o- trimethyl silyl polydimethylsiloxane. Representative examples of commercially available monomers comprising polysiloxane groups include X-22-174ASX, X22- 174BX, KF-2012, X-22-2426 and X-22-2404 from Shin-Etsu, Silaplane FM-0711, Silaplane FM-0721, Silaplane FM-0725 from JNC Corporation, PS560 from United Chemical Technologies and MCR-M07, MCR-M11, MCR-M17, MCR-M22 and MCR-V41 from Gelest;

(meth)acrylic acid momomers comprising polyether groups such as polyethylene glycol)methyl ether (meth)acrylate, polypropylene glycol) methyl ether (meth)acrylate, poly(ethylene glycol) ethyl ether (meth)acrylate, polypropylene glycol) ethyl ether (meth)acrylate, polyethylene glycol) (meth)acrylate, polypropylene glycol) (meth)acrylate. Representative examples of commercially available monomers include Visiomer MPEG 750 MA W, Visiomer MPEG 1005 MA W, Visiomer MPEG 2005 MA W, Visiomer MPEG 5005 MA W from Evonik, Bisomer PPA6, Bisomer PEA6, Bisomer PEM6, Bisomer PPM5, Bisomer PEM63P, Bisomer MPEG350MA, Bisomer MPEG550MA, Bisomer SIOW, BisomerS20W from Geo Speciality Chemicals, SR550 MPEG350MA, SR552 MPEG500MA from Sartomer and RPEG 750 from Ineos Oxide;

(meth)acrylic acid ester monomers that are hydrolysable such as silyl (meth)acrylate monomers and metal ester (meth)acrylic monomers. Examples of such monomers are trialkyl silyl monomers such as triisopropyl silyl (meth)acrylate, zinc (meth)acrylate and zinc acetate (meth)acrylate, copper (meth)acrylate and copper acetate (meth)acrylate.

In one particularly preferred embodiment, the polymeric binder comprises a residue of at least one, and preferably at least two, monomers of formula (I)

wherein R¹ is H or CH3;

R² is H or optionally a linear, branched or cyclic substituted C1-18 alkyl, wherein said substituents are selected from OH, OR³ and N(R⁴)?; and

R³ is selected from C1-8 alkyl and C3-8 cycloalkyl.

Each R⁴ is independently selected from H, C1-8 alkyl and C3-8 cycloalkyl

It is to be understood that the polymeric binder of the present invention may be a co-polymer comprising several of the monomers described above.

The polymeric binder of the present invention preferably comprises at least 50 wt% of the structural unit derived from an ethylenically unsaturated monomer, preferably at least 70 wt%, more preferred at least 80 wt% relative to the total weight of the polymeric binder. In one preferred embodiment the polymeric binder of the present invention comprises at least 95 wt% of the structural units derived from ethylenically unsaturated monomers, preferably 100 wt%.

The polymeric binder of the present invention preferably comprises a (meth)acrylic acid and/or a (meth)acrylic acid ester monomer. Preferably the polymeric binder of the present invention comprises at least 15 wt%, relative to the total weight of the polymeric binder of (meth)acrylic acid and/or (meth)acrylic acid ester monomers, preferably at least 20 wt%, more preferably at least 40 wt%, still more preferably at least 55 wt%. In general, the (meth)acrylic acid and/or (meth)acrylic acid ester monomer is present in an amount of 99.9 wt% or less, more preferably 99.5 wt% or less, relative to the total weight of the polymeric binder.

The amount of each structural unit can be determined by, for example, nuclear magnetic resonance spectroscopy (NMR) or pyrolysis gas chromatography mass spectrometry (Pyro-GC/MS). Information about the wt.% (meth)acrylic acid and/or (meth)acrylic acid ester parts in a commercially available polymeric binder is also often easily obtainable from the supplier. The polymeric binder of the invention may be produced by methods known in the art. In general, this involves appropriately selecting one or more ethylenically unsaturated monomers, in amounts in consideration of, for example, the structural unit and weight average molecular weight, and then using a known method, for example, emulsion polymerization to polymerise said monomers.

The amount of polymeric binder in the antifouling coating composition is preferably 1.0 to 40 wt%, more preferred 2.0 to 35 wt%, further preferred 2.5 to 25 wt% of the total dry weight of the coating composition.

The glass transition temperature (Tg) of the polymeric binder is not particularly limited and can be, for example, less than 50°C.

In a particularly preferred embodiment, the polymeric binder of the present invention is in the form of a dispersion or emulsion.

The polymeric binder is typically present in the dispersion/emulsion in the form of particles or droplets with an average size of 4 to 1000 nm, preferably 25 to 400 nm, more preferably 50 to 350 nm, such as 100 to 300 nm. The “average size” referred to in this context is the Z-average size, which will be understood to be the intensity weighted average hydrodynamic diameter as described in ISO22412:2017. It will be understood that in this context the polymeric binder particles form the dispersed phase of the dispersion/emulsion.

The polymeric binder droplets or particles preferably form 10 to 80 wt% of the dispersion/emulsion, relative to the total weight of the dispersion/emulsion as a whole. Typical wt% ranges may be 35 to 60 wt%, such as 40 to 55 wt%, relative to the total weight of the dispersion/emulsion as a whole.

In addition to the polymeric binder droplets or particles, the dispersion/emulsion comprises an aqueous solvent (i.e. the continuous phase). It will be understood that an aqueous solvent is one comprising (preferably consisting of) water. The dispersion/emulsion referred to herein may thus be termed an aqueous dispersion/emulsion. The aqueous dispersion/emulsion of the polymeric binder is a dispersion/emulsion in which the polymeric binder is dispersed in a dispersion medium including water (hereinafter, also referred to as “aqueous medium”). The aqueous medium is not particularly limited as long as it includes water; however, the content of water in the aqueous medium is preferably 50 to 100 wt%, and more preferably 60 to 90 wt% relative to the total weight of the aqueous medium. In one preferred embodiment the content of water in the aqueous medium is 100 wt%, e.g. the aqueous medium consists of water. The aqueous medium may include a medium other than water, and examples of such a medium include acetone, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-methoxy ethanol, 2-ethoxy ethanol, 2-butoxyethanol, 1- methoxy-2-propanol, l-ethoxy-2-propanol, diacetone alcohol, dioxane, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, dipropylene glycol monomethyl ether (Dowanol DPM), ethylene glycol monopropyl ether, and ethylene glycol monohexyl ether. One or more of these can be used.

The solvent (preferably water) forms 10 to 70 % of the volume of the dispersion/emulsion, relative to the total volume of the dispersion/emulsion as a whole. Typical volume% ranges may be 20 to 65 %, such as 30 to 60 %, relative to the total volume of the dispersion as a whole.

The dispersion/emulsion may be prepared by any suitable known method in the art.

The dispersion/emulsion may comprise a surfactant. The surfactant may be non-ionic, anionic, cationic or amphoteric.

Examples of non-ionic surfactants are alkyl phenoxy ethers, polyalkylene glycols, polyoxyalkylene sorbitan monooleates, polyvinyl alcohols, polyvinyl esters, polyether siloxanes, fatty alcohol ethoxylates and sorbitan stearates. Preferred non- ionic emulsifying agents are polyalkylene glycols such as polyoxyethylenepolyoxypropylene co-polymers and fatty alcohol ethoxylates.

Examples of anionic surfactants are alkyl-, aryl-, alkaryl- sulphates, sulphonates, phosphates, sulpho-succinates, sulphosuccinamates, sulphoacetates and amino acid derivatives.

Particularly preferred anionic surfactants are alkylsulfate salts, polyoxyethylene alkyl ether sulfate salts, unsaturated aliphatic sulfonate salts, and hydroxylated aliphatic sulfonate salts. The alkyl group referenced here can be exemplified by medium and higher alkyl groups such as decyl, undecyl, dodecyl, tridecyl, tetradecyl, cetyl, stearyl, and so forth. The unsaturated aliphatic group can be exemplified by oleyl, nonenyl, and octynyl. The counterion can be exemplified by sodium ion, potassium ion, lithium ion, and ammonium ion, with the sodium ion being typically used among these.

The cationic surfactant can be exemplified by quaternary ammonium salttype surfactants such as alkyltrimethylammonium salts, e.g., octadecyltrimethylammonium chloride and hexadecyltrimethylammonium chloride, and dialkyldimethylammonium salts, e.g., dioctadecyldimethylammonium chloride, dihexadecyldimethylammonium chloride and didecyldimethylammonium chloride.

The amphoteric surfactant can be exemplified by alkylbetaines and alkylimidazolines.

The dispersions/emulsions may also comprise crosslinkers, curing catalysts, antifoaming agents, rheology modifiers and pH adjusting agents. Suitable antifoaming agents, rheology modifiers and pH adjusting agents are described further under additives.

From the viewpoint of the stability of the dispersion/emulsion, the volume solid is preferably 30 % or more, more preferably 40 wt% or more, relative to the total volume of the dispersion/emulsion. Typically, the volume solid is 80 % or less, preferably 70 % or less, relative to the total volume solid of the dispersion/emulsion as a whole.

Example of suitable commercially available dispersions/emulsions include PRIMAL™ AC-337, PRIMAL™ SF-021 and MAINCOTE™ 1071 from Dow Chemical company.

An aqueous dispersion/emulsion of the polymeric binder can be prepared by dispersing the polymeric binder with a surfactant to form a dispersion/emulsion. In addition, a dispersion/emulsion can be directly prepared by emulsion polymerisation of the monomers forming the polymeric binder. The surfactant is not particularly limited, and can be appropriately selected from a cationic surfactant, an anionic surfactant, and a nonionic surfactant as described above.

The dispersion/emulsion of the polymeric binder preferably forms 2 to 45 wt% of the antifouling coating composition, relative to the total weight of the composition as a whole. Typical wt% ranges may be 3 to 40 wt%, such as 5 to 35 wt%, relative to the total weight of the composition as a whole.

Rosin or a rosin derivative

The antifouling coating composition of the invention further comprises rosin or a rosin derivative. It is to be understood that the rosin or rosin derivative of the invention is also considered to be part of the binder system in the antifouling coating composition layer.

The rosin of use in the invention can be rosin or a rosin derivative such as a salt thereof e.g. as described below. Rosins of interest may be rosin acids. Rosin acids are also referred to as resin acids. It will be appreciated that the rosin acids are derived from natural sources and as such they typically exist as a mixture of acids. Examples of rosin acids are abietic acid, neoabietic acid, dehydroabietic acid, palustric acid, pimaric acid, levopimaric acid, isopimaric and sandaracopimaric acid. Representative examples of sources of rosin acids are gum rosin, wood rosin and tall oil rosin. Gum rosin, also referred to as colophony and colophonium, is particularly preferred. Preferred rosin acids are those comprising more than 85 % rosin acids and still more preferably more than 90 % rosin acids.

Rosin derivatives which may be used in the invention include hydrogenated and partially hydrogenated rosin, disproportionated rosin, dimerised rosin, polymerised rosin, maleic acid esters, fumaric acid esters, glycerol esters, methyl esters, pentaerythritol esters and other esters of rosin and hydrogenated rosin, copper resinate, zinc resinate, calcium resinate, magnesium resinate and other metal resinates of rosin and polymerised rosin and others as described in WO 97/44401.

A single rosin or rosin derivative as defined above may be employed, or a mixture of two or more such rosins or rosin derivatives.

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.

In one preferred embodiment the antifouling coating composition of the present invention comprises rosin.

The rosin or rosin derivative is preferably dispersed in water. The rosin or rosin derivative is typically present in the dispersion in the form of droplets or particles with an average size of 50 to 1500 nm, preferably 100 to 1200 nm, more preferably 150 to 1000 nm. The “average size” referred to in this context is the Z-average size, which will be understood to be the intensity weighted average hydrodynamic diameter as described in ISO22412:2017.

It will be understood that in this context the rosin or rosin derivative droplets or particles form the dispersed phase of the dispersion.

The rosin or rosin derivative droplets or particles preferably form 30 to 90 wt% of the dispersion, relative to the total weight of the dispersion as a whole. Typical wt% ranges may be 35 to 80 wt%, such as 40 to 70 wt%, relative to the total weight of the dispersion as a whole.

In addition to the rosin or rosin derivative droplets or particles, the dispersion comprises aqueous solvent (i.e. the continuous phase). It will be understood that an aqueous solvent is one comprising (preferably consisting of) water. The dispersion referred to herein may thus be termed an aqueous dispersion.

The solvent (preferably water) forms 10 to 70 wt% of the dispersion, relative to the total weight of the dispersion as a whole. Typical wt% ranges may be 20 to 65 wt%, such as 30 to 60 wt%, relative to the total weight of the dispersion as a whole. The dispersion may be prepared by any suitable known method in the art.

The dispersion may comprise surfactants, such as those hereinbefore defined for the dispersions of the polymeric binder. The dispersion may also comprise antifoaming agents, preservatives, pH adjusting agents and/or rheology modifiers. Suitable antifoaming agents, rheology modifiers, preservatives and pH adjusting agents are described further under additives.

Metal carboxylate salts of rosin acid and rosin acid derivatives may also be present in the antifouling coating composition of the present invention. Examples of metal carboxylate salts include alkali metal salts such as sodium and potassium carboxylate salt, alkaline earth metal carboxylate salt such as magnesium carboxylate salt and calcium carboxylate salt or transition metal carboxylate salt such as copper carboxylate salt and zinc carboxylate salt. Transition metal carboxylate salts are preferred such as rosin acid zinc salts (zinc rosinate) and rosin acid copper salts (copper rosinate). The metal carboxylate salts may be added directly to the antifouling coating composition or be generated in situ in the antifouling coating composition.

The dispersion of the rosin or rosin derivative preferably forms 0.5 to 30 wt% of the antifouling coating composition, relative to the total weight of the composition as a whole. Typical wt% ranges may be 1.0 to 25 wt%, such as 2.0 to 20 wt%, relative to the total weight of the composition as a whole.

To ensure sufficient polishing and mechanical properties, the amount of rosin or rosin derivative should be at least 1.0 wt%, relative to the total dry weight of the coating composition. Typical wt% ranges for the rosin or rosin derivative(s) are 1.0 to 30 wt%, such as 1.2 to 25 wt%, more preferably 1.5 to 20 wt%, relative to the total dry weight of the coating composition. Where the coating composition comprises more than one rosin or rosin derivative, these wt% ranges will be understood to corresponds to the total for all rosin or rosin derivatives present.

Preferably the ratio between the rosin or rosin derivative and the polymeric binder is 5:95 to 95:5, preferably 20:80 to 80:20, more preferably 30:70 to 70:30.

It is preferred therefore that the antifouling coating composition comprises i) 2 to 45 wt% of polymeric binder dispersion relative to the total weight of the composition as a whole; ii) 1.0 to 25 wt% of dispersion of the rosin or rosin derivative; and iii) at least 10 wt% water.

Other Binder components

In addition to the polymeric binder and rosin or rosin derivative described above, additional binder(s) can be used to adjust the properties of the antifouling coating composition. Examples of binders that can be used include: polyethylene glycol) copolymers; saturated aliphatic polyesters, such as poly(lactic acid), poly(glycolic acid), poly(2-hydroxybutyric acid), poly (3 -hydroxybutyric acid), poly(4-hydroxy valeric acid), polycaprolactone and aliphatic polyester copolymer containing two or more of the units selected from the above mentioned units; and polymeric plasticizers from any of the polymer groups specified above. Additional examples of other binder components that may be present in the antifouling coating composition of the invention include:

Polyurethane-based binder systems;

Hydrocarbon resins, such as hydrocarbon resin formed only from the polymerisation of at least one monomer selected from a C> aliphatic monomer, a C9 aromatic monomer, an indene coumarone monomer, or a terpene or mixtures thereof; and monocarboxylic acids other than the rosin acids described above.

Examples of suitable monocarboxylic acids are C6-C20 cyclic monocarboxylic acid, C5-C24 acyclic aliphatic monocarboxylic acid, C7-C20 aromatic monocarboxylic acid, a derivative of any of the monocarboxylic acids, and mixtures thereof.

Derivatives of monocarboxylic acid include metal salts of monocarboxylic acid, such as alkali metal carboxylate, alkaline earth metal carboxylate (e.g. calcium carboxylate, magnesium carboxylate) and transition metal carboxylate (e.g. zinc carboxylate, copper carboxylate). Preferably the metal carboxylate is a transition metal carboxylate, particularly preferably the metal carboxylate is a zinc carboxylate or copper carboxylate. The metal carboxylate may be added directly to the antifouling coating composition or be generated in situ in the antifouling coating composition.

Representative examples of C6-C20 cyclic monocarboxylic acids include naphthenic acid, 1 ,4-dimethy 1 -5-(3 -methy 1 -2-buteny 1 )-3 -cyclohexen- 1 -yl- carboxylic acid, 1 , 3 -dimethy 1 -2-(3 -methy 1 -2-buteny 1 )-3 -cyclohexen- 1 -yl- carboxylic acid, 1,2,3- trimethyl-5-(l-methyl-2-propenyl)-3-cyclohexen-l-yl- carboxylic acid, l,4,5-trimethyl-2-(2-methyl-2-propenyl)-3-cyclohexen-l-yl- carboxylic acid, 1 ,4, 5-trimethy 1 -2-(2-methyl-l-propeny 1 )-3 -cyclohexen- 1 -yl- carboxylic acid, 1,5, 6-trimethy 1-3 -(2-methy 1-1 -propeny 1 )-4-cyclohexen- 1 -yl- carboxylic acid, 1 -methyl-4-(4-methyl-3 -penteny 1 )-4-cyclohexen- 1 -yl-carboxylic acid, 1 -methyl -3 -(4-methyl-3 -penteny l)-3 -cycloh exen-l-yl-carboxylic acid, 2- methoxycarbony 1 -3-(2-methy 1 - 1 -propeny l)-5, 6-dimethyl-4-cyclohexen- 1 -y 1 - carboxylic acid, l-isopropyl-4-methylbicyclo[2,2,2]2-octen-5-yl-carboxylic acid, 1- isopropyl-4-methyl-bicyclo[2,2,2]2-octen-6-yl-carboxylic acid, 6-isopropyl-3- methyl-bicyclo[2,2,2]2-octen-8-yl-carboxylic acid and 6-isopropyl-3-methyl- bicyclo[2,2,2]2-octen-7-yl-carboxylic acid.

Representative examples of C5-C24 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 and 12,15-dimethylhexadecanoic acid. The acyclic aliphatic monocarboxylic acid is preferably selected from liquid, acyclic C10-C24 monocarboxylic acids or liquid, branched C10-C24 monocarboxylic acids. It will be appreciated that many of the acyclic C10-C24 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.

Preferably the monocarboxylic acid is acyclic C10-C24 monocarboxylic acids, C6-C20 cyclic monocarboxylic acids or mixtures thereof.

Additives

The antifouling coating composition of the present invention optionally comprises one or more additives. Examples of additives that may be present in the coating composition of the invention include, rheology modifiers, antifoaming agents, pH adjusting agents, dispersing agents, wetting agents, coalescing agents and plasticizers.

The coating composition of the invention preferably comprises a rheology modifier. A mixture of two or more rheology modifiers may be employed. The presence of a rheology modifier in the compositions of the invention advantageously improves the storage stability, the body of the coating composition and the application properties of the coating.

Examples of suitable rheology modifiers are polysaccharide rheology modifiers, associative rheology modifiers, clays, cellulosic rheology modifiers, fumed silica or a mixture thereof. Exemplary polysaccharide rheology modifiers for use in the coating compositions include alginin, guar gum, locust bean gum and xanthan gum.

Exemplary clay rheology modifiers for use in the coating compositions of the invention include kaolin clay, smectite clay, illite clay, chlorite clay, synthetic clay or organically modified clay. Preferred clay rheology modifiers are synthetic clay or an organically modified clay.

Exemplary associative rheology modifiers for use in the coating compositions include non-ionic synthetic associative rheology modifier (niSAT), hydrophobically modified alkoxylated urethanes such as hydrophobically modified ethoxylated urethanes (HEUR), hydrophobically modified alkali-swellable emulsions (HASE), and styrene-maleic anhydride terpolymers (SMAT). Acidic acrylate copolymers (cross-linked) of ethyl acrylate and methacrylic acid, and acrylic terpolymers (cross-linked) of ethyl acrylate, methacrylic acid, and non-ionic urethane surfactant monomer may also be used as associative rheology modifiers. Particularly preferred associative rheology modifiers present in the coating compositions of the invention are hydrophobically modified ethoxylated urethanes (HEUR).

Preferably rheology modifiers are present in the composition of the invention in an amount of 0-10 wt%, more preferably 0.1-6 wt% and still more preferably 0.1- 2.0 wt%, based on the total dry weight of the composition.

The coating composition of the present invention may comprise an antifoaming agent. Antifoaming agents are sometimes also referred to as foam control agents or defoamers. A wide range of antifoaming agents are commercially available, and may be used in the coating compositions of the invention. Representative examples of suitable antifoaming agents include organic siloxanes, polyethers, polyether-modified silicones, mineral oils and combinations thereof. Preferred coating compositions of the invention comprise 0-2.0 wt% antifoaming agent based on the total weight of the coating composition.

The coating composition of the present invention may comprise a pH adjusting agent such as ammonia, 2-aminopropanol, sodium hydroxide (NaOH), sodium carbonate (ISfeCCE) and sodium bicarbonate (NaHCCE). Coalescing agents may optionally be included. In a waterborne paint composition, the applied wet product is inhomogeneous, as opposed to a solventborne composition which will be homogenous when applied. In order to form a film the polymeric binder droplets or particles must coalesce. Coalescing agents aid this process in the water phase. Examples of suitable coalescing agents are ester alcohol, benzyl alcohol, propylene glycol monomethyl ether (PM), propylene glycol propyl ether (PnP), dipropylene glycol n-butyl ether (DPnB), propylene glycol phenyl ether (PPh), tripropylene glycol n-butyl ether (TPnB), ethylene glycol propyl ether (EP), ethylene glycol butyl ether (EB), diacetone alcohol (DAA) and dipropylene glycol methyl ether (DPM).

In order to improve or facilitate dispersion of the pigments, fillers and biocides it may be desirable to incorporate wetting/dispersion additives that are compatible with a water-borne coating composition. A wide range of dispersing agents is commercially available, and may be used in the coating compositions of the invention. Suitable dispersing agents include conventional anionic, cationic, nonionic and amphoteric dispersing agents as well as combinations thereof.

Examples of suitable dispersing agents are polyalkylene glycol, polyacrylamide, polyethercarboxylate, polycarboxylates and sodium salts of acrylic polymers.

A plasticizer may be added to the coating composition of the present invention. Examples of suitable plasticizers are silicone oils (non-reactive polydimethylsiloxanes), chlorinated paraffins, phthalates, phosphate esters, sulphonamides, adipates, epoxidised vegetable oils and sucrose acetate isobutyrate.

Solvent

The antifouling coating composition of the present invention is a waterborne composition, i.e. one comprising water as the main solvent.

The antifouling coating composition of the present invention preferably comprises water as the main solvent.

Low amounts of organic co-solvents may be present such as ketones, alcohols, glycol ethers or other oxygen-containing solvents that are soluble or miscible with water. Preferably the coating composition comprises less than 10 wt% of an organic solvent, further preferred less than 5 wt% or an organic solvent relative to the total weight of the composition as a whole. The antifouling coating composition may be organic solvent free.

The coating compositions comprise at least 5 wt% water, relative to the total weight of the composition as a whole. Preferably the coating compositions comprise at least 10 wt% water relative to the total weight of the composition as a whole. Preferably, the compositions comprise 5 to 60 wt% water, more preferably 10 to 50 wt%, such as 15 to 40 wt%, relative to the total weight of the composition as a whole.

Biocide

The antifouling coating composition of the invention preferably additionally comprises a compound capable of preventing settlement or growth of marine fouling on a surface. The terms antifouling agent, antifoulant, biocide, active compounds, toxicant are used in the industry to describe known compounds that act to prevent marine fouling on a surface. The antifouling agents of the invention are marine antifouling agents.

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 copper oxides, e.g. cuprous oxide and cupric oxide, copper thiocyanate and copper sulfide, copper powder and copper flakes.

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

Examples of organic marine antifouling agents include heterocyclic compounds such as 2-(tert-butylamino)-4-(cyclopropylamino)-6-(methylthio)-l,3,5- triazine [cybutryne], 4,5-dichloro-2-w-octyl-4-isothiazolin-3-one [DCOIT], 1,2- benzisothiazolin-3-one, 3 -(3, 4-di chlorophenyl)- 1,1 -dimethylurea [diuron], N- dichlorofluoromethylthio-7V',7V'-dimethyl-7V-phenylsulfamide [dichlofluanid], N- dichlorofluoromethylthio-7V',7V'-dimethyl-7V-/?-tolylsulfamide [tolylfluanid], N- (2,4,6-trichlorophenyl)maleimide, triphenylborane pyridine [TPBP], 3-iodo-2- propynyl -butylcarbamate [IPBC], 2,4,5,6-tetrachloroisophthalonitrile [chlorothalonil], /?-((diiodomethyl)sulphonyl)toluene, 4-bromo-2-(4-chlorophenyl)- 5-(trifluoromethyl)-lH-pyrrole-3-carbonitrile [tralopyril], 4-[l-(2,3-dimethylphenyl)ethyl]-lH-imidazole [medetomidine].

Other examples of marine antifouling agents may be tetraalkylphosphonium halogenides, quaternary ammonium salts, guanidine derivatives such as dodecylguanidine monohydrochloride; macrocyclic lactones including avermectins and derivatives thereof such as ivermectine; spinosyns and derivatives such as spinosad; capsaicin and derivatives such as phenylcapsaicin; and enzymes such as oxidase, proteolytically, hemicellulolytically, cellulolytically, lipolytically and amylolytically active enzymes. Complexes such as copper di(ethyl-4,4,4- trifluoroacetoacetate (Cu(ETFAA)2 as described in EP3860349 and WO2021113564 may also be used in the antifouling formulation.

Copper based antifouling coating compositions contain inorganic copper biocides such as metallic copper, cuprous oxide, copper thiocyanate and the like to prevent hard fouling.

The cuprous oxide material has a typical 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 to prevent surface oxidation and caking. Examples of commercially available cuprous oxide paint grades include Nordox Cuprous Oxide Red Paint Grade and Nordox XLT, Cuprous oxide orange from Nordox AS, Furukawa Cuprous oxide from Furukawa Chemicals Co., Ltd.; Red Copp 97, Purple Copp 97, LoLo Tint LM, LoLo Tint NP, LoLo Tint LM B/B, from American Chemet Corporation; Cuprous Oxide Red from Cosaco; Cuprous oxide Roast, Cuprous oxide Electrolytic from Taixing Smelting Plant Co., Ltd.

Another example of commercially available grades of inorganic copper is e.g., Cuprous thiocyanate from Bardyke Chemicals Ltd.

The copper pyrithione material (needle shaped powder) has a typical average particle size (d50) of 2-7 pm and may contain surfactants for stabilisation. Examples of commercially available material is Copper Omadine from Arxada (Arch Chemicals B.V.); CleanBio from Kolon Life Science. Trade names for some suitable antifouling agents are Econea (tralopyril, from Janssen and Kolon Life Science); Selektope (Medetomidine from I-Tech); SeaNine 21 IN (DCOIT from DuPont Microbial Control), SeaNine Ultra (encapsulated DCOIT from DuPont Microbial Control); UmiGard Pro and UmiGard SynPro (from Arxada), Perozine Marine (Zineb from Agria S.A.); Zineb Nautec (Zineb from United Phosphorus).

Antifouling coating compositions without inorganic copper biocides typically use a series of organic biocides such as 4-[l-(2,3-dimethylphenyl)ethyl]- IH-imidazole [medetomidine] and 4-bromo-2-(4-chlorophenyl)-5-(trifluoromethyl)- lH-pyrrole-3-carbonitrile [tralopyril] to prevent hard fouling. Any known biocide can be used in the invention, including in-can preservatives described under additives for the primer layer (I).

Preferred biocides are cuprous oxide, copper powder, copper thiocyanate, copper sulfide, zinc pyrithione, copper pyrithione, zinc ethylenebis(dithiocarbamate) [zineb], 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one [DCOIT], N- dichlorofluoromethylthio-N',N'-dimethyl-N-phenylsulfamide [dichlorofluanid], N- dichlorofluoromethylthio-N',N'-dimethyl-N-p-tolylsulfamide [tolylfluanid], triphenylborane pyridine [TPBP] and 4-bromo-2-(4-chlorophenyl)-5- (trifluoromethyl)-lH-pyrrole-3-carbonitrile [tralopyril], 4-[l-(2,3- dimethylphenyl)ethyl]-lH-imidazole [medetomidine] and phenylcapsaicin.

A mixture of biocides can be used as is known in the art as different biocides operate against different marine fouling organisms. Mixtures of antifouling agents are generally preferred.

In one embodiment the antifouling coating composition comprises 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, tralopyril and medetomidine.

In an alternative embodiment the antifouling coating is free of an inorganic copper biocide. In this embodiment, a preferred biocide combination involves a combination of tralopyril and one or more selected from zinc pyrithione, copper pyrithione, zineb, 4,5-dichloro-2-octyl-4-isothiazolin-3-one and medetomidine. Where present, the combined amount of biocides may form up to 60 wt% of the coating composition, such as 0.1 to 50 wt%, e.g. 5 to 45 wt%, relative to the total weight of the coating composition. Where inorganic copper compounds are present, a suitable amount of biocide might be 5 to 60 wt% relative to the total weight of 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% relative to the total weight of the coating composition.

Where present the combined amount of biocides may form up to 70 wt% of the coating composition, such as 0.1 to 60 wt%, e.g 10 to 60 wt% relative to the total dry weight of the coating composition.

It will be appreciated that the amount of biocide will vary depending on the end use and the biocide used. The biocides described herein may optionally be included in layer (I).

Some biocides may be encapsulated or adsorbed on an inert carrier or bonded to other materials for controlled release. Some biocide may be surface treated to improve stability, dispersibility and/or controlled release. These percentages refer to the amount of active biocide present and not therefore to any carrier used.

Pigments, extenders and fillers

In addition to the polymeric binder, rosin or rosin derivative, biocides (including cuprous oxide) and any of the optional components described above, the antifouling coating composition according to the present invention may optionally further comprise one or more components selected among inorganic or organic pigments, extenders and fillers.

The pigments may be inorganic pigments, organic pigments or a mixture thereof. Inorganic pigments are preferred. 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, naphthol red and diketopyrrolopyrrole red. Pigments may optionally be surface treated to be more easily dispersed in the paint composition. The titanium dioxide may be surface treated with silicone, zinc, zirconium or aluminium.

Examples of extenders and fillers are minerals such as dolomite, plastorite, calcite, quartz, baryte, magnesite, aragonite, silica, nepheline syenite, wollastonite, talc, chlorite, mica, kaolin, pyrophyllite, perlite, silica and feldspar; synthetic inorganic compounds such as calcium carbonate, magnesium carbonate, barium sulfate, calcium silicate, zinc phosphate and silica (colloidal, precipitated, fumed, etc.); polymeric and inorganic microspheres such as uncoated or coated hollow and solid glass beads, uncoated or coated hollow and solid ceramic beads, porous and compact beads of polymeric materials.

Preferably the total amount of extender, filler and/or pigment present in the antifouling coating compositions of the invention is 2-60 wt%, more preferably 5-50 wt% and still more preferably 7-45 wt%, based on the total weight of the composition.

Preferably the total amount of extender, filler and/or pigment present in the compositions of the invention is 2 to 80 wt%, preferably 5 to 70 wt%, more preferably 10 to 65 wt% of the total dry weight of the coating composition

The skilled person will appreciate that the extender, filler 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 antifouling coating composition.

Examples of reinforcing fillers are flakes and fibres. Fibres include natural and synthetic inorganic fibres and natural and synthetic organic fibres e.g. as described in WO 00/77102. Representative examples of fibres include 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 pm and an average thickness of 1 to 50 pm with a ratio between the average length and the average thickness of at least 5. Preferably reinforcing fillers 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 flaky fillers are mica, glass flakes and micronized iron oxide

(MiO).

Hollow spheres as described under layer (I) may be present in layer (II), e.g. as hollow glass spheres and hollow ceramic spheres. The antifouling coating composition may comprise 0.25 to 10 wt%, more preferably 1.0 to 7.5 wt% hollow spheres.

Antifouling coating composition properties

The antifouling coating composition of the invention should preferably have solids content above 35 vol%, e.g. above 40 vol%, such as above 42 vol%. Values up to 65 %vol. solids are possible.

The antifouling coating composition of the invention should preferably have solids content of 50 to 90 wt% such as 60 to 80 wt%.

More preferably the antifouling coating composition should have a content of volatile organic compounds (VOC) of less than 200 g/L, preferably less than 150 g/L, more preferably less than 100 g/L, e.g. less than 70 g/L. VOC content can be calculated as described in e.g. ASTM D5201 - 05a(2020) or IED 2010/75ZEU or measured, e.g. as described in US EPA Method 24 or ISO 11890-2.

The antifouling coating composition of the invention ideally has a pigment volume concentration (PVC) of less than 80%, more preferably less than 60%, further preferred less than 55%, e.g. 30 to 55 %. Pigment Volume Concentration (PVC) is defined as the ratio of pigment volume to the total dry film volume.

Applications

The antifouling coating system of the invention can be applied to a whole or part of any object which is subject to fouling. The antifouling coating system of the present invention may be applied to any suitable surface, such as metal substrates such as carbon steel, galvanized steel, stainless steel or aluminium. Furthermore, the antifouling coating system may be applied to metal substrates with a non-optimal surface treatment such as rusted substrates, ultra-high pressure water-jetted substrates, substrates containing old paint residues of paint as well as precoated substrates. Other substrates include fiberglass and gel-coat substrates, e.g. those which form the hulls of yachts. Whilst these substrates tend not to corrode, the primer layer of the invention still provides a suitable base layer onto which a antifouling coating layer can be applied.

The surface may be permanently or intermittently underwater (e.g. through tide movement, different cargo loading or swell). The object surface will typically be the hull of a vessel or surface of a fixed marine object such as an oil platform or buoy.

The compositions as described herein may be prepared in a suitable concentration for use, e.g. in spray painting. In this case, the compositions themselves are a paint. Alternatively, the compositions may be a concentrate for preparation of paint. In this case, further solvent and optionally other components are 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 coating composition or paint is preferably filled into a container. Suitable containers include cans, drums and tanks.

The primer composition of layer (I) may be supplied as a one-pack, as a two- pack or as a three-pack. Preferably the composition is supplied as a two-pack.

Thus, the primer composition of layer (I) as hereinbefore defined may be supplied as a kit of parts, wherein said kit comprises:

(i) a component A comprising at least one epoxy-based binder and water; and

(ii) a component B comprising an amine based curing agent and a silane, as herein defined.

The primer composition and paint of the invention preferably has a solids content of 40-90 wt%, more preferably 50-80 wt% and still more preferably 55-70 wt%. In terms of solids by volume percent solids (volume solids%), the primer composition and paint of the invention preferably has a solids content of 30 to 80%, more preferably 40 to 75% and still more preferably, 45 to 70%.

The coating system comprises at least layer (I) and layer (II). These should be directly adjacent and hence the use of a tie-coat is avoided. If a substrate is being repainted, the coating system may be applied over an old coating system. The coating system may thus additionally comprise one or more additional layers selected from the group consisting of a shop primer, an epoxy-primer and a topcoat. Shop primer, topcoat, tie-coat, are all well-known terms in the art.

In some cases the antifouling coating system consists of layer (I) and layer (II).

Preferably layer (I) is the first coating layer of the system, i.e. is applied directly to the substrate. Optionally the substrate may be pre-treated with a shop primer before applying a coating layer consisting of the hereinbefore defined primer composition (I).

Layer (II) is applied directly on layer (I).

In one embodiment, layer (I) and/or layer (II) have been cured and/or dried.

The coating compositions may be cured or dried at ambient and elevated temperatures (e.g. 18 to 40 °C), or at lower temperatures, such as 10 to 18 °C, preferably they can also cure or dry at even lower temperatures such as 5 to 18 °C.

The coating compositions of the present invention can be cured or dried at a relative humidity of 40 to 80%, preferably 30 to 85%, more preferred 20 to 90%, and even more preferred 10 to 90%.

Sufficient ventilation is always necessary when curing or drying waterborne paints, this is especially true when curing at a high relative humidity.

The dry film thickness of each of the coating layers of the coating composition of the present invention is preferably 50 to 500 pm, more preferably 75 to 400 pm, most preferably 100 to 300 pm.

The wet film thickness of the coating composition of the invention is preferably 75 to 1000 pm, more preferably 100 to 800 pm, most preferably 125 to 600 pm.

In order therefore to coat a substrate with the coating system of the invention there are three main steps:

1. Mixing component A and component B of the primer composition.

2. Applying the primer composition (e.g. by airless spray) to a substrate so as to form a coating film and preferably allowing the coating film to dry for at least 0.5 h, preferably at least 60 mins to form the primer layer (I) ;

3. Apply the antifouling coating composition on top of the primer layer. Curing/drying conditions can be -5 to 50 °C at 50%RH, but ideally it is 5 to 40 °C, or 10 to 30 °C.

In general, coating of the primer layer (I) with the antifouling coating layer (II) can occur once the skilled person determines that it is sufficiently dry to tolerate overcoating. This may of course depend on the local conditions at the time of coating system application, e.g. the ambient temperature and humidity.

The invention also relates to substrates coated with the coating system as hereinbefore defined as well as a process for applying a coating system to a substrate comprising applying, e.g. by spraying, layer (I) as hereinbefore defined to a substrate and allowing the coating composition to dry then applying, e.g. by spraying, layer (II) as hereinbefore defined and allowing the coating to dry. The invention also relates to a process for protecting an object from corrosion and fouling with a coating system as hereinbefore defined.

The substrate/object is typically any surface that should be protected by an anticorrosive coating and/or a fouling protection coating. For example, the surface of a marine structure, preferably a marine structure which is submerged when in use. The surface may be permanently or intermittently underwater (e.g. through tide movement, different cargo loading or swell). Typical marine structures include vessels (including but not limited to boats, yachts, motorboats, motor launches, ocean liners, tugboats, tankers, container ships and other cargo ships, submarines, and naval vessels of all types), pipes, shore and off-shore machinery, constructions and objects of all types such as piers, pilings, bridge substructures, water-power installations and structures, underwater oil well structures, nets and other aquatic culture installations, and buoys, etc. The surface of the substrate may be the "native" surface (e.g. the steel surface).

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 object. Typically, the surface will need to be separated from the seawater to allow coating. After the coating is applied, it is preferably dried and cured. The application of the coating can be achieved as conventionally known in the art. The overcoating interval is the interval of time between the end of the application of the primer layer (I) and the start of the application of the antifouling coating layer (II). Primer coatings have both a minimum and maximum overcoating time. The maximum overcoating time is the time allowed before unacceptable intercoat adhesion will take place. Extending the overcoating interval is advantageous, as it provides flexibility when applying the antifouling coating composition. A sufficiently high overcoating interval for a primer/antifouling systems is necessary due to logistics at yard/shop. The maximum overcoating time is at least 24 hours, preferably at least 48 hours, more preferably at least 5 days, such as at least 1 week or 2 weeks.

The invention will now be defined with reference to the following nonlimiting examples.

Examples

The densities, volume percent solids (volume solids%), and the theoretical volatile organic compounds (VOC) content of the compositions were calculated according to ASTM D5201 - 05a(2020).

Pigment volume concentration for the compositions were determined by calculation according to the formula PVC = ((Vp + Vf)/(Vp+Vf+Vb))*100. Where Vp is the volume of pigments, Vf is the volume of fillers, including glass spheres, and Vb is the volume of binders.

The specific gravity of the coating compositions are theoretical values obtained by calculations.

The Tg is obtained by Differential Scanning Calorimetry (DSC) measurements. Typically, the measurement is performed by running a heat-cool-heat procedure, within a temperature range from -80°C to 150°C, with a heating rate of 10°C/min and cooling rate of 10°C/min and using an empty pan as reference. 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 rosin ester.

Materials used Primers

WB-primers 1 and 2 are waterborne epoxy primers based on Bis-A epoxy resin and a modified polyamine curing agent containing a cyclic structure. WB- primer 1 is based on a dispersed solid epoxy resin and WB-primer 2 is based on an emulsified liquid epoxy resin. Primers used in the comparative examples include WB-primer 3, 4 and 5 which are commercially available water-borne epoxy primers, SB-primer 1 and 2 which are commercially available solvent-borne epoxy primers, and SF-primer which is a commercially available solvent-free epoxy primer. Table 1 Raw materials used in WB-Primer 1 and WB-Primer 2

Table 2. Composition of WB-Primers 1 and 2, component A

Table 3. Composition ofWB-primer 1 and 2, component B

Table 4. Paint parameters, WB-primer 1 and 2

Description of Solvent borne and solvent free primers used in comparative examples

None of the solvent borne or solvent free primers contain any solid thermoplastic resin as typically found in tie coats.

SB-Primer l is a solvent-borne epoxy primer comprising solid epoxy resin and a polyamide curing agent. 60% solids by volume, 396 g/L VOC.

SF-Primer is a solvent-free epoxy primer comprising liquid Bis-F epoxy resin and a polyamine amine curing agent. 97% solids by volume, 8 g/L VOC.

SB-Primer 2 is a solvent-borne primer comprising semi-solid epoxy resin and a phenalkamine curing agent. 72% solids by volume, 261 g/L VOC.

Water borne primers used in comparative examples

WB-Primer 3* is a water-borne epoxy primer comprising liquid epoxy resin and a waterborne polyamine-adduct curing agent. Contains 19 wt% liquid epoxy, 11 wt% of a 80% wt. solid water-dilutable polyamine adduct, 4 wt% hydrocarbon resin and 5 wt% added co-solvent.

WB-Primer 4* is a water-borne epoxy primer comprising an emulsified liquid epoxy resin and a waterborne polyamine-adduct curing agent. Contains 34wt% of a 70% wt solid emulsified liquid epoxy resin, 16 wt% of a 80% wt. solids water-dilutable polyamine-adduct and 4 wt% added co-solvent.

WB-Primer 5* is a water-borne epoxy primer comprising a dispersed semi-solid epoxy resin and a waterborne poyamine-adduct curing agent. Contains 42 wt% of a 57% wt. solid dispersed semi-solid epoxy resin, 7 wt% of a 80% wt. solids waterdilutable polyamine-adduct and 4wt% added co-solvent.

None of these water borne primers comprise any silanes and they all comprise a water soluble curing agent and thus also significant amounts of water in the curing-agent component B.

Tie-coat

A commercially available tie-coat, herby referred to as “Tie-coat”, was used in the reference systems containing primer, tie-coat and antifouling. Tie-coat is a solvent borne, polyamide cured, vinyl resin modified epoxy based coating containing 62% solids by volume, 362 g/L VOC.

Antifouling coating composition WB-AF is a waterborne self-polishing antifouling coating. Its binder system comprises acrylic polymer dispersion and rosin dispersion. A more detailed description of WB-AF can be seen in table 5.

Table 5. Waterborne antifouling paint composition in parts by weight%

(^x) Tg 18°C, 42 wt% solids; (²) Dermulsene A7510 from DRT, 56 wt% solids; (³)

Dowanol DPM from Dow Solvent Borne Antifouling coating compositions

SB-AF 1 is a solvent-bome self-polishing antifouling coating. Binder system comprise acrylic polymers and rosin. 59% solids by volume, 389 g/L VOC.

SB-AF 2 is a solvent-bome self-polishing antifouling coating. Binder system comprise silyl-(meth)acrylate, acrylic polymer and rosin. 58% solids by volume, 387 g/L VOC.

SB-AF 3 is a solvent-bome self-polishing antifouling coating. Binder system comprise silyl-(meth)acrylate and rosin. 55% solids by volume, 415 g/L VOC.

General Preparation of WB-primer 1 and WB-primer 2

For preparation of component A, a suitable amount of epoxy binder was added to a vessel and mixed with a solution of wetting and dispersing agent and water. Fillers, pigments and any anti-corrosive pigments are then added to the vessel while stirring. This mixture makes up the mill-base. The speed of the dissolver-blade is increased to impart enough shear-force on the mill-base as to ensure a good grinding efficiency. The rheology modifier is then added, if suitable for addition, and stable, at high shear forces. Optionally, a defoamer is added to the grinding step to prevent a build-up of air bubbles/foam in the mill-base.

When the fineness of grind is deemed suitable for the paint the speed of the dissolver blade is reduced and more water is added as to thin the mixture. Additives such as defoamers, surface-tension additives, biocides, flash rust inhibitors and rheology modifiers are then added, in addition to more water and the rest for the epoxy binder. Any organic solvents, or other raw materials that are deemed suitable for the formulation such as hollow glass spheres, tinters, hydrocarbon resins, diluents and silanes, can be added at any appropriate time during the manufacturing process.

For preparation of component B, the curing agent and silane is simply mixed in a vessel, optionally with organic solvents, diluents, and/or hydrocarbon resins, or other raw materials deemed suitable. If pigments, fillers and/or hollow glass spheres are to be included in component B a suitable rheology modifier should be employed to increase the storage stability of the component, i.e. to stabilize the glass spheres so that these do not float to the surface of the mixture. Hydrocarbon resin is added to a vessel and mixed with a suitable solvent. Polyamide wax is then added and stirred into the mixture for 5-10 minutes. Extenders and/or pigments are added to the mixture to make up the mill-base and to achieve a suitable volume and viscosity for grinding. The speed of the dissolverblade is then increased to impart enough shear-force on the mixture as to ensure a good grind efficiency and to increase the temperature of the mixture to the activation temperature of the polyamide wax, typically between 45 °C and 65 °C. A defoamer may optionally be added to prevent the build-up of air-bubbles or foam in the mixture. When a temperature suitable for activation of the polyamide wax has been reached the speed of the dissolver is reduced so that the shear force exerted on the paint keeps the temperature stable inside a temperature range suitable for the activation process. The mixture is then stirred for 10-15minutes, while activating the polyamide wax. Solvents are then added to reduce the viscosity and temperature of the paint before adding curing agent(s) and silanes(s). Lastly the hollow glass spheres are stirred into the mixture at a suitable mixing speed to ensure an even incorporation and to prevent any structural damage to the spheres. Any other raw materials deemed suitable for the coating composition may be added at any appropriate time during the manufacturing process.

Preparation of WB-AF

Preparation of WB-AF was done by mixing pigments, extenders, biocides, and additives and grinding at high shear using a dissolver with impeller blade until the mill base had fineness of grind below 40 pm. Then the stirring rate was reduced, and the binder ingredients were added slowly. More additives were post-added when/if needed.

Application, curing and testing - Example 1

The compatibility between epoxy primers and antifouling coating compositions was tested. 24 different coating systems (Table 6) comprising 6 different epoxy primers, four different antifouling paints and one tie-coat were made to investigate the properties of waterborne primer and waterborne antifouling coating in an anticorrosive primer/antifouling coating system. The system containing SB-primer 2 and Tie-coat was used as a reference.

Table 6. Overview of coating systems used - Coating systems 1 and 2 are of the invention

VOC/m² for each of the coating systems has been calculated based on theoretical VOC concentration and the volume solids percent for each paint and is listed in table 9. Two coats of primer were applied to Sa2.5 grade grit-blasted steel panels with a 24 hour coating-interval. One coat of the tie coat was then applied to coating system 6, 12, 18 and 24 after an additional 24 hours. After further 24 hours two coats of antifouling coating composition were applied to all panels, with an overcoating interval of 24 hours. All paints were applied with airless spray at ambient conditions.

The fully coated panels were dried at ambient temperature for another 7 days prior to immersion in 40 °C seawater (ISO 2812-2). The coating systems were thus cured and dried for 11 days from the application of the first coat of primer to the initiation of the seawater immersion testing. Each coat of primer, antifouling and tie-coat were applied at a wet filmthickness (WFT) sufficient to produce a dry film-thickness (DFT) of 150pm, 175pm and 100pm respectively.

Results Example 1

The coating systems were evaluated after 2 months and 4 months of exposure to 40°C seawater immersion. Pull off, cross-cut and X-cut tests were conducted to characterize the adhesion properties between primers and antifouling coatings.

A method based on ASTM D3359 was used for cross-cut and X-cut; a procedure based on ASTM D4541 was used to evaluate the pull-off strength. For the cross-cut test, a cutting tool was used to make 6 parallel cutting lines in vertical and horizontal directions. Then a soft brush was used to clean the surface very gently. The adhesion was evaluated as described in Table 7, no tape was used to test adhesion. For the X-cut test, two intersecting cuts were made in the film at an angle of 30-45°. After gentle brushing with a soft brush, the X-cut area was examined and evaluated as described in Table 7, no tape was used to test adhesion. The pull-off strength was evaluated 48 hours after removing the panels from the test-chamber. Pull-off values above 2.0 MPa is deemed to be sufficient and will receive a pass score, values below 2.0 MPa will be deemed to be insufficient and will receive a fail score.

The results for each of the tests were evaluated separately, then each coating system was assigned a score from 1 to 4 based on overall performance, as described in Table 8. Results from the adhesion testing and calculation of the VOC/m² for each of the coating systems can be found in table 9 The calculated theoretical VOC/m² values are based on the wet film-thickness (WFT) needed to produce a dry film-thickness (DFT) of 150pm, 175pm and 100pm for each coat of the primers, antifoulings and tie-coat respectively. The WFT is calculated by dividing the desired DFT by the volume solids of the coating compositions. Thus, for coating system 1, the Primer WFT is 150 gm / 0.59 = 254 gm — >Volume for 1 m² is then 0.254 dm³ (0.254 L). Calculated VOC pr unit area — > VOC [g/L] x volume paint per area [L/m²] = 99.8 g/L x 0.254 L/m² = 25.3 g/m² The WB AF WFT is 175 pm / 0.46 = 380 pm — > volume for 1 m² is then 0.380 L. VOC per unit area = 56 g/L x 0.380 L/m² = 21.3 g/m²

Total VOC two coats primer and two coats AF = (25.3 x 2) + (21.3 x 2) = 93 g/m² Table 7. Classification of adhesion test results from cross-cut tests and X-cut tests

Table 8. Overall characterisation of adhesion properties

Table 9: Calculated VOC emissions in g/m² and performance of coating systems 1 - 24

Coating systems 1 and 2 are of the invention. Coating systems 3 to 5, 9-11, 15-17, 21-23 use a solvent borne or solvent free primer. Coating systems 7-12, 13- 18 and 19-24 use a solvent borne antifouling coating. Coating systems 6, 12, 18 and 24 use a tie-coat.

WB-AF applied on WB-primer (coating systems 1 and 2) shows good adhesion properties in the absence of a tie-coat.

WB-AF applied on solvent-borne primers (coating systems 3 and 5) and solvent-free primer (coating system 4) demonstrate good adhesion properties.

WB-AF applied on top of a tie-coat layer (coating system 6) demonstrates good adhesion properties.

Solvent-borne antifouling paints applied on solvent-borne primers (coating systems 9-11, 15-17 and 21-23) show poor adhesion properties.

SB-AF 1 and SB-AF 2 demonstrate good adhesive properties on tie-coat only (coating systems 12 and 18). When applied directly on solvent-free, solvent- borne and waterborne primers (coating systems 7-11 and 13-17), the adhesion properties are poor.

Application, curing and testing - Example 2

12 coating systems (Table 10) were made to investigate how the overcoating interval between primer composition and antifouling coating composition affects the adhesion performance of the antifouling coating systems. For these 12 systems the antifouling coating was applied after 14 days of curing of the primer/tie-coat. Table 10. Coating systems used - Systems 25 and 26 are of the invention

The application, curing and testing process was identical to that described above, other than the difference in overcoating interval between the primer and antifouling coating application, which for systems 25-36 was 14 days, and the exposure time was shortened to 3 months due to the longer drying/curing period. Results, which are graded according to Tables 7-8, are shown in Table 11.

Table 11. Performance of coating systems 25-36

The tie-coat free systems 31-35, comprising SB-AF 2, all have low overall score which correlates with the test results for systems 13-18. System 36 which contains a tie-coat passes.

Systems 25-30, comprising WB-AF, pass, except for system 28 where the primer is solvent free SF-Primer. This indicates that a SF-Primer is not suitable in a tie-coat free system containing WB-AF due to short overcoating window.

Application, curing and testing - Example 3

To ensure that the primer used in the compatibility tests between primer and antifouling coating will not fail, accelerated corrosion-testing of different waterborne epoxy primers were performed. The solvent-borne and solvent-free primers used in test-series 1 were not included as these are commercially available primers with anticorrosive performance sufficiently good for underwater use. The following epoxy primers were tested: WB-primer 1, WB-Primer 3, WB-Primer 4 and WB-Primer 5.

Two coats of primer were applied to Sa2.5 grade grit-blasted steel panels with a 24 hour coating-interval. All paints were applied with airless spray at ambient conditions at a wet film-thickness (WFT) sufficient to produce a dry film-thickness (DFT) of 150 pm per coat.

The fully coated panels were cured at ambient temperature for 14 days prior to immersion in 40 °C seawater (ISO 2812-2) for 4 and 6 months and exposure to cathodic disbondment test (ISO 15711) for 6 months.

After exposure the panels were evaluated based on X-cut and pull-off adhesion (ASTM D3359 and ASTM D4541 respectively) as well as observed defects. X-cut was graded according to Table 7. Pull-off was graded as pass if pull- off value is greater than 5 and no inter-coat adhesion was observed, and fail if not. Radial disbondment was graded pass if lower than 7 mm and fail if higher than 7 mm. The results can be found in tables 12 and 13. Table 12. Results from the 40°C Seawater Immersion test

Table 13. Results from Cathodic disbondment test

Silane containing WB-primer 1 passed both tests and showed no sign of developing defects during the test period. Silane free WB-Primer 3, WB-Primer 4 and WB-Primer 5 failed both tests and developed severe defects. Only WB-Primer 1 is suitable for use in submerged areas. Summary

WB-primers 1 and 2 have a sufficiently high anticorrosive performance to be used in submerged areas. The other waterborne primers did not.

None of the tie-coat free solvent-borne coating systems (i.e. where both primer and antifouling coating compositions are solvent based) showed sufficient performance. Whereas all of the systems containing a tie-coat performed well and are included to demonstrate what a successful product might look like. It is remarkable that the coating systems of the invention perform at the same level as the tie-coat based systems even though no tie-coat is present.

WB-AF is compatible with both solvent-borne and waterborne primers but the reduction in VOC/m² is greater if combined with a WB-primer (system 1) - 61% and 38% reduction compared to tie-coat free systems 3 and 5. The reduction in VOC/m² is between 55% and 78% for coating system 1 relative to systems 6, 12, 18 and 24, where tie-coat is included.

The tie-coat free system containing SF-Primer and WB-AF is not suitable for use due to the short overcoating window. A system consisting of WB-AF, SF-Primer and tie-coat would emit 10% more VOC/m² than coating system 1.

The present invention significantly reduces VOC emissions compared to currently used coating systems whilst maintaining overall performance. Interlayer adhesion is good and anticorrosive properties are good. The coating system of the invention also has an excellent overcoating window.

Furthermore, the present invention reduces workload and has fewer logistics in the paint application phase due to a reduction in the number of coats for a suitable system. Due to short drying time the use of a waterborne primer also makes it possible to apply several coats in one shift, which further reduces the time it takes to apply the whole coating system.

Claims

Claims

1. An antifouling coating system comprising a primer layer (I) and antifouling coating layer (II) directly adjacent thereto, wherein: primer layer (I) comprising a primer composition comprising components A and B, wherein component A comprises: i) 15 to 70 wt% of one or more epoxy-based binders relative to the total weight of component A, such as a bisphenol type epoxy resin; and ii) 20 to 60 wt% water, relative to the total weight of component A; wherein component B comprises: i) an amine based curing agent; and ii) a silane, such as an amino functional silane; and wherein component B comprises less than 5 wt% water, relative to the total weight of component B; and antifouling coating layer (II) comprising an antifouling coating composition comprising: a) a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer; and b) at least 1.0 wt% based on dry weight of the total composition, of rosin or a rosin derivative; wherein the antifouling coating composition comprises at least 5 wt% water relative to the total weight of the antifouling coating composition as a whole.

2. The antifouling coating system according to any preceding claim, wherein the amine based curing agent in layer (I) comprises a cyclic structure, such as one comprising a benzyl amine motif.

3. The antifouling coating system according to any preceding wherein said polymeric binder comprises (meth)acrylic acid and/or (meth)acrylic acid ester monomers, preferably wherein the polymeric binder comprises at least 15 wt%, relative to the total weight of the polymeric binder of (meth)acrylic acid and/or (meth)acrylic acid ester monomers

4. The antifouling coating system according to any preceding claim, wherein layer (I) has been cured.

5. The antifouling coating system according to any preceding claim, wherein the primer composition has a volatile organic compound (VOC) content of less than than 120 g/L, more preferably less than 100 g/L and/or the antifouling coating composition has a volatile organic compound (VOC) content of less than 200 g/L, preferably less than 150 g/L, more preferably less than 100 g/L, even more preferably less than 70 g/L.

6. The antifouling coating system according to any preceding claim, wherein the primer composition has a pigment volume concentration (PVC) of 20 to 50%, such as 30 to 45% and/or the antifouling coating composition has a PVC of less than 80%, preferably less than 60%, such as less than 55%.

7. The antifouling coating system according to any preceding claim, wherein the antifouling coating composition further comprises one or more biocides.

8. The antifouling coating system as claimed in any preceding claim, wherein said polymeric binder is in the form of an aqueous dispersion or emulsion.

9. The antifouling coating system as claimed in any preceding claim wherein said rosin or rosin derivative is a rosin acid or mixture of rosin acids, such as gum rosin, wood rosin and tall oil rosin or a rosin derivative selected from hydrogenated and partially hydrogenated rosin, disproportionated rosin, dimerised rosin, polymerised rosin, maleic acid esters, fumaric acid esters, glycerol esters, methyl esters, pentaerythritol esters and other esters of rosin and hydrogenated rosin, copper resinate, zinc resinate, calcium resinate, magnesium resinate and other metal resinates of rosin and polymerised rosin.

10. The antifouling coating system as claimed in any preceding claim wherein component B preferably comprises i) 5 to 40 wt% amine based curing agent; ii) 0.25 to 10 wt% silane; and optionally iii) 10 to 30 wt% hydrocarbon resin.

11. The antifouling coating system as claimed in any preceding claim wherein the antifouling coating composition comprises i) 2 to 45 wt% of polymeric binder dispersion relative to the total weight of the composition as a whole; ii) 1.0 to 25 wt% of dispersion of the rosin or rosin derivative; iii) at least 10 wt% water; and optionally iv) a biocide.

12. The antifouling coating system according to any preceding claim, wherein the system consists of layer (I) and layer (II).

13. The antifouling coating system according to any preceding claim wherein the epoxy-based binder of component A is in the form of a dispersion or emulsion.

14. The antifouling coating system according to any preceding claim wherein the silane does not react with the curing agent but does react with the epoxy based binder, such as an aminosilane.

15. A process for the preparation of an antifouling coating system comprising a primer layer (I) and antifouling coating layer (II) directly adjacent thereto, wherein said process comprises: obtaining a component A comprising: i) 15 to 70 wt% of one or more epoxy-based binders relative to the total weight of component A, such as a bisphenol type epoxy resin; and ii) 20 to 60 wt% water, relative to the total weight of component A; obtaining a component B comprising: i) an amine based curing agent; and ii) a silane, such as an amino functional silane; and wherein component B comprises less than 5 wt% water, relative to the total weight of component B; and applying on a substrate a blend of components A and B so as to form a primer layer (I), and obtaining an antifouling coating composition comprising: a) a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer; and b) at least 1.0 wt% based on dry weight of the total composition, of rosin or a rosin derivative; wherein the antifouling coating composition comprises at least 5 wt% water relative to the total weight of the antifouling coating composition as a whole; and applying said antifouling coating composition onto said primer layer (I) to form an antifouling coating layer (II) directly adjacent thereto.

16. A process as claimed in claim 15 wherein the primer layer (I) is allowed to dry before application of the antifouling coating layer (II).

17. A substrate, such as a marine substrate, coated with the coating system as defined in any of claims 1 to 14, wherein said coating system has been allowed to dry or a substrate obtained by the process of claims 15 to 16.

18. An antifouling coating system comprising a primer layer (I) and antifouling coating layer (II) directly adjacent thereto, wherein: the primer layer (I) is formed from a primer composition comprising components A and B, wherein component A comprises: i) 15 to 70 wt% of one or more epoxy-based binders relative to the total weight of component A; and ii) 20 to 60 wt% water, relative to the total weight of component A; wherein component B comprises: i) an amine based curing agent; and ii) a silane; and wherein component B comprises less than 5 wt% water, relative to the total weight of component B; and wherein the antifouling layer (II) is formed from an antifouling coating composition comprising: a) a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer; and b) at least 1.0 wt% based on dry weight of the total composition, of rosin or a rosin derivative; wherein the antifouling coating composition comprises at least 5 wt% water relative to the total weight of the antifouling coating composition as a whole.

19. A substrate having a dry primer layer (I) comprising one or more epoxybased binders, such as a bisphenol type epoxy resin; an amine based curing agent; and a silane, such as an amino functional silane; and a wet antifouling coating layer (II) directly adjacent thereto, wherein: said wet antifouling coating layer (II) comprises a) a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer; and b) at least 1.0 wt% based on dry weight of the total composition, of rosin or a rosin derivative; wherein the antifouling coating composition comprises at least 5 wt% water relative to the total weight of the antifouling coating composition as a whole.