阅读说明：本技术 水性涂料组合物、涂覆有该组合物的基材、使用该涂料组合物控制水生生物污损的方法 (Aqueous coating composition, substrate coated with the composition, and method of controlling biofouling of aquatic organisms using the coating composition ) 是由 J·弗格森 A·A·芬尼 于 2020-03-30 设计创作，主要内容包括：本发明涉及一种水性涂料组合物,其包含溶解在包含水和水混溶性溶剂的液相中的丙烯酸类聚合物,其中所述涂料组合物包含至少50重量％的水,并且其中所述丙烯酸类聚合物是可通过单体混合物的自由基聚合获得的成膜聚合物,所述单体混合物包含30-70重量％的聚(乙二醇)(甲基)丙烯酸类单体a；2-20重量％的烷氧基甲硅烷基或烷氧基烷基甲硅烷基官能的(甲基)丙烯酸类单体b；和10-68重量％的疏水性烯属不饱和单体c。本发明进一步涉及一种涂覆有该涂料组合物的基材,一种控制人造物体表面上的水生生物污损的方法,以及该涂料组合物用于控制人造物体上水生生物污损的用途。(The present invention relates to an aqueous coating composition comprising an acrylic polymer dissolved in a liquid phase comprising water and a water miscible solvent, wherein the coating composition comprises at least 50 wt% water, and wherein the acrylic polymer is a film forming polymer obtainable by free radical polymerization of a monomer mixture comprising 30-70 wt% of a poly (ethylene glycol) (meth) acrylic monomer a; 2-20 weight percent of an alkoxysilyl or alkoxyalkyl silyl functional (meth) acrylic monomer b; and 10 to 68% by weight of hydrophobic ethylenically unsaturated monomers c. The invention further relates to a substrate coated with the coating composition, a method of controlling aquatic fouling on the surface of an artificial object, and the use of the coating composition for controlling aquatic fouling on an artificial object.)

1. An aqueous coating composition comprising an acrylic polymer dissolved in a liquid phase comprising water and a water-miscible solvent, wherein the coating composition comprises at least 50 wt% water, and wherein the acrylic polymer is a film-forming polymer obtainable by free radical polymerization of a monomer mixture comprising:

-30-70% by weight of a poly (ethylene glycol) (meth) acrylic monomer of general formula (I):

wherein:

R¹is H atom or methyl;

a is an O atom or an NH group, preferably an O atom;

R²is a hydrogen atom,Alkyl or phenyl having 1 to 6 carbon atoms; and is

n is an integer of 2 to 100;

-2-20% by weight of an alkoxysilyl or alkoxyalkyl silyl functional (meth) acrylic monomer of general formula (II):

CH₂＝CR¹-CO-A-R^a-[X-R^a]_k-Si(R³)_(3-n)(OR⁴)_n (II)

wherein:

R¹is H atom or methyl;

a is an O atom or an NH group, preferably an O atom;

R^a-[X-R^a]_kis a group having 1 to 20 carbon atoms, wherein:

each R^aIndependently selected from (i) aliphatic hydrocarbon groups, and (ii) aromatic hydrocarbon groups optionally having one or two substituents selected from the above (i); wherein the aliphatic hydrocarbon group and the aromatic hydrocarbon group in the above (i) or (ii) may each optionally be substituted by one or more groups selected from the group consisting of-C_1-3Alkyl, -N (R)^b)₂and-OR^bSubstituted with the substituent(s);

each R^bIndependently selected from H and C_1-3An alkyl group;

x is selected from A, -C (O) O-, -OC (O) -, -C (O) NR^b-and-NR^bC(O)；

k is an integer of 0 to 3,

n is 1, 2 or 3, preferably 2 or 3;

R³and R⁴Independently an alkyl or alkoxyalkyl group having 1 to 6 carbon atoms; and

-10-68% by weight of hydrophobic ethylenically unsaturated monomers c, selected from styrene, alkylated styrene and (meth) acrylic monomers of general formula (III):

CH₂＝CR¹-CO-A-R⁵ (III)

wherein:

R¹is H atom or methyl;

a is an O atom or an NH group; and is

R⁵To be provided withA hydrocarbon group of 1 to 18 carbon atoms, preferably an alkyl group having 1 to 12 carbon atoms or an (alkyl) aryl group having 6 to 12 carbon atoms.

2. The coating composition of claim 1 comprising 15-35 wt% of an acrylic polymer, based on the total weight of the coating composition.

3. The coating composition of claim 1 or 2, wherein the poly (ethylene glycol) acrylic monomer a. has the general formula (I), R²Is a H atom, a methyl group, an ethyl group or a phenyl group, preferably a methyl group, and n is an integer of 2 to 100.

4. The coating composition according to any one of the preceding claims, wherein the water miscible solvent is a mono-or diether of ethylene or propylene glycol having a boiling point of 70-180 ℃ or an alkyl alcohol having a boiling point of 70-180 ℃.

5. The coating composition according to any one of the preceding claims, wherein monomer b. has the general formula (II) and a is an O atom, m is an integer from 1 to 6, n is 2 or 3, and R³And R is independently an alkyl group having 1 to 6 carbon atoms, preferably methyl or ethyl.

6. The coating composition according to any one of the preceding claims, wherein monomer c.

7. A coating composition according to any preceding claim wherein moiety R in monomer b^a-[X-R^a]_kIs (C)_mH_2m) Wherein m is an integer from 1 to 20, preferably from 1 to 6.

8. The coating composition of any of the preceding claims further comprising a silanol condensation catalyst, optionally having a tertiary amine group.

9. A substrate coated with the coating composition of any one of the preceding claims.

10. The substrate according to claim 9, wherein the substrate is coated with a multi-coating system comprising:

-optionally a primer layer applied to the substrate and deposited from the primer coating composition;

-a tie coat layer applied to the substrate or optional primer layer, deposited from a tie coat composition comprising a binder polymer dissolved in an organic solvent, the binder polymer having curable alkoxysilyl or alkoxyalkyl silyl functional groups and comprising less than 10 wt% of water; and

-a topcoat layer applied onto the tie coat layer, the topcoat layer being deposited from the coating composition according to any one of claims 1-8.

11. The substrate of claim 10, wherein the binder polymer in the tie-coating composition is a poly (meth) acrylate having curable alkoxysilyl or alkoxyalkyl silyl functional groups.

12. The substrate of claim 10 or 11, wherein the tie coating composition further comprises a silanol condensation catalyst.

13. A method of controlling aquatic biofouling on a surface of an artificial object, comprising the steps of:

(a) applying a coating composition according to any one of claims 1-8 to at least a portion of a surface of a man-made object;

(b) curing the coating composition to form a cured coating; and

(c) at least partially immersing the man-made object in water.

14. The method of claim 13, further comprising the step of applying a tie coat to at least a portion of the surface of the man-made object prior to applying the coating composition of step (a), wherein the tie coat is deposited from the tie coat composition of claim 12, and the tie coat composition is partially cured prior to applying the coating composition of step (a).

15. Use of a coating composition according to any one of claims 1 to 8 for controlling biofouling of aquatic organisms on a manufactured object.

Technical Field

The present invention relates to an aqueous coating composition, a substrate coated with the coating composition, a method of controlling aquatic biofouling on the surface of an artificial object, and the use of the coating composition for controlling aquatic biofouling on an artificial object.

Background

Man-made objects such as boat and boat hulls, buoys, drilling platforms, dry dock equipment, oil production rigs, aquaculture equipment, and nets and pipes submerged in or having water flowing through them, are prone to fouling by aquatic organisms such as green and brown algae, barnacles, mussels, and the like. Such objects are usually metal, but may also be made of other materials, such as concrete, glass reinforced plastic or wood. This fouling is detrimental to ships and boat hulls because it increases frictional resistance during movement through the water. As a result, the speed is reduced and the fuel consumption is increased. It is detrimental to static objects such as legs of drilling platforms and drilling rigs used for oil and gas production, refining and storage because the resistance of thick fouling layers to waves and currents can cause unpredictable and potentially dangerous stresses in the object, and also because fouling makes it difficult to inspect the object for defects such as stress cracking and corrosion. It is detrimental in pipes such as cooling water inlets and outlets because the effective cross-sectional area is reduced by fouling, with a consequent reduction in flow velocity.

Coatings with silicone-based resins are known to resist fouling by aquatic organisms. Such coatings are typically solvent based and relatively expensive. Another disadvantage of coatings with silicone-based resins is that many other resins do not adhere to surfaces contaminated with silicone resins or show film defects if applied to surfaces contaminated with silicone resins. If the surface becomes contaminated with silicone resin due to overspray or overspray of the silicone-based coating, the surface must be cleaned before a primer or other coating can be applied thereto.

There is a need in the art for coating compositions that are soil resistant, contain no or fewer harmful compounds, are relatively inexpensive, and do not cause contamination of other surfaces to be painted.

Brief description of the invention

It has now been found that aqueous coating compositions comprising aqueous dilute solutions of acrylic polymers having hydrolysable alkoxysilyl or alkoxyalkyl silyl groups in water-miscible solvents can suitably be used to provide fouling control properties to substrates immersed in water, such as boat hulls.

Accordingly, the present invention provides in a first aspect an aqueous coating composition comprising an acrylic polymer dissolved in a liquid phase comprising water and a water-miscible solvent, wherein the coating composition comprises at least 50 wt% water, and wherein the acrylic polymer is a film-forming polymer obtainable by free-radical polymerisation of a monomer mixture comprising:

-30-70% by weight of a poly (ethylene glycol) (meth) acrylic monomer of general formula (I):

wherein:

R¹is H atom or methyl;

a is an O atom or an NH group, preferably an O atom;

R²is H atom, alkyl group having 1 to 6 carbon atoms or phenyl group; and is

n is an integer of 2 to 100;

-2-20% by weight of an alkoxysilyl or alkoxyalkyl silyl functional (meth) acrylic monomer of general formula (II):

CH₂＝CR¹-CO-A-R^a-[X-R^a]_k-Si(R³)_(3-n)(OR⁴)_n (II)

wherein:

R¹is H atom or methyl;

a is an O atom or an NH group, preferably an O atom;

R^a-[X-R^a]_kis a group having 1 to 20 carbon atoms, wherein:

each R^aIndependently selected from (i) aliphatic hydrocarbon groups, and (ii) aromatic hydrocarbon groups optionally having one or two substituents selected from the above (i); wherein the aliphatic hydrocarbon group and the aromatic hydrocarbon group in the above (i) or (ii) may each optionally be substituted by one or more groups selected from the group consisting of-C_1-3Alkyl, -N (R)^b)₂and-OR^bSubstituted with the substituent(s);

each R^bIndependently selected from H and C_1-3An alkyl group;

x is selected from A, -C (O) O-, -OC (O) -, -C (O) NR^b-and-NR^bC(O)；

k is an integer of 0 to 3,

n is 1, 2 or 3, preferably 2 or 3;

R³and R⁴Independently an alkyl or alkoxyalkyl group having 1 to 6 carbon atoms; and

-10-68% by weight of hydrophobic ethylenically unsaturated monomers c, selected from styrene, alkylated styrene and (meth) acrylic monomers of general formula (III):

CH₂＝CR¹-CO-A-R⁵ (III)

wherein:

R¹is H atom or methyl;

a is an O atom or an NH group; and is

R⁵Is a hydrocarbon group having 1 to 18 carbon atoms, preferably an alkyl group having 1 to 12 carbon atoms or an (alkyl) aryl group having 6 to 12 carbon atoms.

The aqueous coating composition of the present invention is less expensive than polysiloxane-based coating compositions and does not result in poor adhesion of other coatings in the event that the surface or equipment bearing the coating composition is contaminated.

In a second aspect, the present invention provides a substrate coated with the coating composition of the first aspect of the invention.

In a third aspect, the present invention provides a method of controlling biofouling on a surface of an artificial object, comprising the steps of:

(a) applying a coating composition according to any one of claims 1-8 to at least a portion of a surface of a man-made object;

(b) curing the coating composition to form a cured coating; and

(c) at least partially immersing the man-made object in water.

In a final aspect, the present invention provides the use of a coating composition of the first aspect for controlling biofouling on a manufactured object.

In the further discussion below, the term "(meth) acryl" means "methacryl or acryl". Similar terms like "(meth) acrylate" and "(meth) acryloyloxy" are to be interpreted in the same way, i.e. as "methacrylate or acrylate" and "methacryloyloxy or acryloyloxy", respectively.

Detailed Description

The coating composition of the present invention comprises an acrylic polymer dissolved in a liquid phase comprising water and a water miscible solvent. The coating composition comprises at least 50 wt% water, preferably 50 to 75 wt% water, based on the total weight of the coating composition. Preferably, the coating composition comprises 5 to 30 wt.%, more preferably 8 to 20 wt.% of the water-miscible solvent, based on the total weight of the coating composition. Preferably, the coating composition comprises less than 5 wt.%, more preferably less than 1 wt.%, even more preferably less than 0.1 wt.% of an organic solvent different from the water-miscible solvent.

Reference herein to a water-miscible solvent is to a solvent having a solubility at 25 ℃ of at least 250 g/litre water, preferably at least 300 g/litre water, more preferably at least 500 g/litre water. Particularly preferred are solvents which are completely miscible with water in all proportions. Water miscibility was determined according to ASTM D1722 using deionized water at 25 ℃.

The water-miscible solvent is a solvent for the acrylic polymer and its monomers. Preferably, the water miscible solvent has a boiling point of 70-180 ℃.

Preferably, the water-miscible solvent is a mono-or diether of ethylene glycol or propylene glycol having a boiling point of 70 to 180 ℃ or an alkyl alcohol having a boiling point of 70 to 180 ℃.

More preferably, the water-miscible solvent is selected from the group consisting of 1-methoxypropan-2-ol (propylene glycol methyl ether), ethylene glycol dimethyl ether, 2-butoxyethanol, ethanol, 1-propanol, 2-propanol and 2-butanol.

The aqueous coating composition of the present invention is suitably prepared by diluting a solution of the acrylic polymer in a water-miscible solvent with water.

The solution of acrylic polymer may comprise 40 to 80 wt%, preferably 50 to 75 wt% of acrylic polymer based on the total weight of the solution. In the aqueous coating composition, i.e., after diluting the solution of the acrylic polymer with water, the concentration of the acrylic polymer may be 10 to 40% by weight, preferably 15 to 35% by weight, more preferably 20 to 30% by weight, based on the total weight of the coating composition.

The acrylic polymer is a film-forming polymer and is obtainable by free radical polymerization of a mixture of ethylenically unsaturated monomers. Preferably, the acrylic polymer is prepared by free radical polymerization of monomers in a water miscible solvent. The acrylic polymer is soluble in the aqueous liquid phase of the coating composition, i.e. in a mixture of water-miscible solvent and water, at a temperature of 25 ℃, which is obtained by diluting a solution of the acrylic polymer with water.

The monomer mixture comprises:

-30-70% by weight of a poly (ethylene glycol) (meth) acrylic monomer a.;

-2-20% by weight of an alkoxysilyl or alkoxyalkyl silyl functional (meth) acrylic monomer b.; and

10 to 68% by weight of hydrophobic, ethylenically unsaturated monomers c.

Monomer a. having the following general chemical formula (I):

wherein:

R¹is H atom or methyl;

a is an O atom or an NH group, preferably an O atom;

R²is H atom, alkyl group having 1 to 6 carbon atoms or phenyl group; and is

n is an integer from 2 to 100, preferably from 2 to 25.

Preferably, R²Is a H atom, a methyl group, an ethyl group or a phenyl group, more preferably a H atom or a methyl group. Particularly preferred monomers a. are methoxy poly (ethylene glycol) methacrylates having from 2 to 25 ethylene glycol moieties.

The monomer mixture for making the acrylic polymer may comprise one or more monomers a. The monomer mixture comprises from 30 to 70 wt.%, preferably from 35 to 65 wt.%, more preferably from 40 to 60 wt.% of monomer a.

The monomer mixture further comprises from 2 to 20 wt.%, preferably from 5 to 17 wt.%, more preferably from 8 to 14 wt.% of an alkoxysilyl or alkoxyalkyl silyl functional (meth) acrylic monomer b. The alkoxysilyl or alkoxyalkyl silyl groups provide crosslinking functionality to the acrylic polymer. Monomer b. having the general formula (II):

CH₂＝CR¹-CO-A-R^a-[X-R^a]_k-Si(R³)_(3-n)(OR⁴)_n (II)

wherein:

R¹is H atom or methyl;

a is an O atom or an NH group, preferably an O atom;

R^a-[X-R^a]_kis a group having 1 to 20 carbon atoms, wherein:

each R^aIndependently selected from (i) aliphatic hydrocarbon groups, and (ii) aromatic hydrocarbon groups optionally having one or two substituents selected from the above (i); wherein the aliphatic hydrocarbon group and the aromatic hydrocarbon group in the above (i) or (ii) may each optionally be substituted by one or more groups selected from the group consisting of-C_1-3Alkyl, -N (R)^b)₂and-OR^bSubstituted with the substituent(s);

each R^bIndependently selected from H and C_1-3An alkyl group;

x is selected from A, -C (O) O-, -OC (O) -, -C (O) NR^b-and-NR^bC(O)-；

k is an integer of 0 to 3,

n is 1, 2 or 3, preferably 2 or 3;

R³and R⁴Independently an alkyl or alkoxyalkyl group having 1 to 6 carbon atoms, preferably a methyl or ethyl group.

Aliphatic hydrocarbon radical R^aMay be straight-chain, branched or cyclic, or may comprise a mixture of cyclic and acyclic moieties.

Aromatic hydrocarbon radical R^aCan be C₆-C₁₀An aromatic hydrocarbon group.

In one embodiment, R^a-[X-R^a]_kIs [ C ]_mH_2m]Wherein m is an integer of 1 to 20, preferably 1 to 6.

In embodiments, each R is^bIndependently selected from H and methyl, and in further embodiments, all R are^bThe radical is H.

Preferred are trialkoxysilylalkyl (meth) acrylate monomers and alkyldialkoxysilylalkyl (meth) acrylate monomers. In a preferred embodiment, A is an oxygen atom and R is^a-[X-R^a]_kHaving 1 to 6 carbon atoms, more preferably 3 carbon atoms, n is 2 or 3, and R³And R⁴Independently methyl or ethyl. For example, in such embodiments, R^a-[X-R^a]_kCan be (C)_mH_2m) Wherein m is 1 to 6, for example 3.

Particularly preferred monomers b. are: trimethoxysilylpropyl (meth) acrylate, triethoxysilylpropyl (meth) acrylate, methyldimethoxysilylpropyl (meth) acrylate, ethyldimethoxysilylpropyl (meth) acrylate, methyldiethoxysilylpropyl (meth) acrylate, ethyldiethoxysilylpropyl (meth) acrylate, more particularly trimethoxysilylpropyl methacrylate or triethoxysilylpropyl methacrylate.

Other examples of monomer b include: trimethoxysilylmethyl (meth) acrylate, triethoxysilylmethyl (meth) acrylate, 3- (meth) acrylamidopropyltrimethoxysilane, 3- (meth) acrylamidopropyltriethoxysilane, N- (3- (meth) acryloyloxy-2-hydroxypropyl) -3-aminopropyltrimethoxysilane, N- (3- (meth) acryloyloxy-2-hydroxypropyl) -3-aminopropyltriethoxysilane, ((meth) acryloyloxymethyl) phenethyltrimethoxysilane, ((meth) acryloyloxymethyl) phenethyltriethoxysilane, O- ((meth) acryloyloxyethyl) -N- (trimethoxysilylpropyl) carbamate, N- (meth) acryloyloxy-2-hydroxypropyl) -3-aminopropyltriethoxysilane, N- (meth) acryloyloxy-2-hydroxypropyl) -3-aminopropyl-triethoxysilane, N- (meth) acryloyloxymethyl-2-propyltrimethoxysilane, N- (meth) acryloyloxymethyl-2-propyltriethoxysilane, O- ((meth) acryloyloxyethyl) -N- (trimethoxysilylpropyl) carbamate, N- (meth) propyltrimethoxysilane, N- (meth) propyltriethoxysilane, N-2-ethyltriethoxysilane, O- (meth) propyltrimethoxysilane, and N- (meth) propyltriethoxysilane, O- (meth) acrylate, and N- (meth) acrylate, O- ((meth) acryloyloxyethyl) -N- (triethoxysilylpropyl) carbamate, N- (3- (meth) acryloyloxy-2-hydroxypropyl) -3-aminopropyltrimethoxysilane and N- (3- (meth) acryloyloxy-2-hydroxypropyl) -3-aminopropyltriethoxysilane.

The monomer mixture may comprise one or more monomers b.

The monomer mixture comprises from 10 to 68 wt.%, preferably from 25 to 60 wt.%, more preferably from 20 to 50 wt.% of hydrophobic ethylenically unsaturated monomers c. Monomer c. is selected from styrene, alkylated styrene or a (meth) acrylic monomer of formula (III):

CH₂＝CR¹-CO-A-R⁵ (III)

wherein:

R¹is a H atom orA methyl group;

a is an O atom or an NH group; and is

R⁵Is a hydrocarbon group having 1 to 18 carbon atoms, preferably an alkyl group having 1 to 12 carbon atoms or an (alkyl) aryl group having 6 to 12 carbon atoms.

Monomer c. is an ethylenically unsaturated monomer having no hydrophilic or crosslinkable functional groups. The monomer mixture may comprise one or more monomers c.

Preferably, the monomer c.is styrene, an alkylated styrene, such as dimethylstyrene, or C of acrylic acid or methacrylic acid₁-C₁₂An alkyl ester. More preferably, monomer c is methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, lauryl (meth) acrylate, isobornyl (meth) acrylate, styrene, or a mixture of two or more thereof. In a particularly preferred embodiment, the monomer c.

The monomer mixture may comprise ethylenically unsaturated monomers other than monomers a, b, and c, for example vinyl monomers such as vinyl acetate, vinyl chloride, vinylidene chloride, ethyl vinyl ether, butyl vinyl ether; or a hydrophilic (meth) acrylic monomer other than the monomer a, such as a zwitterionic (meth) acrylic monomer or a (meth) acrylic monomer having a salt group. Preferably, the monomer mixture comprises not more than 10 wt.%, preferably not more than 5 wt.%, of ethylenically unsaturated monomers other than monomers a. If the monomer mixture comprises hydrophilic (meth) acrylic monomers other than monomer a, the total amount of hydrophilic (meth) acrylic monomers, i.e. the sum of monomer a and hydrophilic (meth) acrylic monomers other than monomer a, is at most 70 wt. -%, preferably at most 60 wt. -%, based on the total weight of the monomers.

In one embodiment, the monomer mixture does not comprise any ethylenically unsaturated monomers other than monomers a.

Preferably, the monomer mixture is free of fluorinated ethylenically unsaturated monomers.

The acrylic polymer may be obtained by free radical polymerization of the monomer mixture. Free radical polymerization is well known in the art, and acrylic polymers can be prepared by any known suitable free radical polymerization method. The conditions for polymerizing monomers into acrylic polymers by free radical polymerization are well known in the art. Any suitable conditions may be applied. Suitable conditions generally include the presence of an initiator and a temperature sufficient to allow polymerization. In general, the temperature during the polymerization is from 50 to 120 ℃ and preferably from 70 to 100 ℃. It will be appreciated that the optimum polymerization temperature will depend on the decomposition temperature of the initiator used as well as the boiling point of the water-miscible solvent and the monomers used.

The acrylic polymer is preferably prepared by radical polymerization of the monomer mixture in a water-miscible solvent, so that it is obtained directly as a solution in the water-miscible solvent.

Any suitable initiator may be used in suitable amounts. Suitable initiators are known in the art and include organic peroxides and azo initiators, such as Azobisisobutyronitrile (AIBN) or 2,2' -azobis (2-methylbutyronitrile) (AMBN). Suitable organic peroxides include benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, acetyl peroxide, t-butyl peroctoate, t-amyl peroctoate, and t-butyl perbenzoate. The initiator may be added in any suitable amount, typically up to 3 mole%, preferably 1.0 to 3.0 mole%, based on the total moles of monomers. The total amount of initiator can be added in two or three steps, i.e.a certain amount is added at the beginning of the polymerization and a further amount is added during the polymerization.

Optionally, a chain transfer agent is used during the polymerization. Any suitable chain transfer agent may be used in suitable amounts. Suitable chain transfer agents are known in the art and include methyl mercaptopropionate, dodecyl mercaptan, n-octyl mercaptan, thioglycolic acid, 2-mercaptoethanol, and butenediol. Optionally, a polymerization catalyst is used during the polymerization. Suitable catalysts are known in the art and are commonly referred to as "activators".

The acrylic polymer preferably has a glass transition temperature of from-25 ℃ to +10 ℃, more preferably from-20 ℃ to +5 ℃, even more preferably from-15 ℃ to +2 ℃. Reference herein to glass transition temperature refers to the calculated Fox glass transition temperature of the non-crosslinked polymer.

The coating composition is cured by condensation of silanol groups formed upon hydrolysis of alkoxysilyl or alkoxyalkyl silyl groups. It has been found that if the acrylic polymer is diluted as in the coating composition of the present invention, the silanol groups will not or hardly condense. Upon drying of the applied coating composition film, the water and water-miscible solvent evaporate, increasing the concentration of the acrylic polymer, resulting in silanol condensation.

The aqueous coating composition may be provided as a one-part composition that is water-diluted, or as a two-part composition in which the acrylic polymer solution is in one part and the water-diluted catalyst is in the other part.

Preferably, the coating composition does not contain any binder polymer other than the acrylic polymer.

The aqueous coating composition may comprise a silanol condensation catalyst. The catalyst catalyzes the hydrolysis of alkoxysilyl or alkoxyalkyl silyl groups and the crosslinking of silanol groups formed upon the hydrolysis. Preferably, the coating composition comprises a silanol condensation catalyst. The catalyst can be used in any suitable amount, preferably from 0.01 to 2 weight percent based on the total weight of the coating composition.

Any water soluble catalyst suitable for catalyzing the condensation reaction between silanol groups may be used. Such catalysts are well known in the art and include tertiary amines, such as 1, 8-diazabicyclo (5.4.0) undec-7-ene (DBU), and strong acids, such as p-toluenesulfonic acid, sulfuric acid, and methanesulfonic acid. The catalyst may comprise a halogenated organic acid having at least one halogen substituent on a carbon atom in the alpha-position relative to the acid group and/or at least one halogen substituent on a carbon atom in the beta-position relative to the acid group, or may be hydrolysed under the condensation reaction conditions to form a derivative of the acid.

It has been found that silanol condensation catalysts comprising tertiary amine groups provide catalytic activity and in-can stability of the polymer. Therefore, the silanol condensing catalyst preferably has a tertiary amine group. Examples of such catalysts include 1, 8-diazabicyclo (5.4.0) undec-7-ene (DBU), 1,5, 7-triazabicyclo [4.4.0] dec-5-ene (TBD), hydroxybenzotriazole, hydroxyazenzotriazole, 5-nitropyridin-2-ol, imidazole, alkylimidazole such as 1-methylimidazole, 2-ethyl-4-methylimidazole or 2-heptadecylimidazole, arylimidazole such as 2-phenylimidazole, alkylarylimidazole such as 2-phenyl-4-methylimidazole, 1, 4-diazabicyclo [2.2.2] octane (DABCO), N-methylmorpholine and tetramethylguanidine. More preferably, the silanol condensation catalyst is DBU or TBD.

To provide enhanced protection from fouling, the coating composition may comprise a biocide. Any biocide known to have biocidal activity against marine or freshwater organisms can be used in suitable amounts. Suitable marine biocides are well known in the art and include inorganic biocides such as copper oxide, copper thiocyanate and copper flake, organometallic or metal-organic biocides such as copper pyrithione, zinc pyrithione and zineb, or organic biocides such as 4, 5-dichloro-2-n-octyl-3 (2H) -isothiazolone, 2- (p-chlorophenyl) -3-cyano-4-bromo-5-trifluoromethylpyrrole (tralopyril) and medetomidine. An advantage of the coating composition of the present invention is that it is capable of providing anti-fouling properties without the need for biocides.

An advantage of the coating composition of the present invention is that it can provide fouling control without the need for biocides. Thus, the coating composition is preferably free of biocides.

The coating composition may further comprise extender pigments (fillers) and/or colour pigments and one or more additives commonly used in coating compositions.

The total amount of color and extender pigments in the coating composition is preferably from 0 to 10% by weight, more preferably from 0 to 5% by weight, based on the total weight of the coating composition.

The total amount of additives other than biocides in the coating composition is preferably from 0 to 3 wt.%, more preferably from 0 to 2 wt.%, based on the total weight of the coating composition.

The invention further relates to a substrate coated with the coating composition of the first aspect of the invention. The coating composition may be applied by known techniques for applying liquid coating compositions, such as brushing, rolling, dipping, bar coating or spraying (airless and conventional) application.

The substrate may be the surface of a structure to be immersed in water, such as a metal, concrete, wood or polymer substrate. Examples of polymeric substrates are composites of polyvinyl chloride based materials or fiber reinforced resins. In an alternative embodiment, the substrate is a surface of a flexible polymeric carrier foil. The coating composition is then applied to one surface of a flexible polymeric carrier foil, such as a polyvinyl chloride carrier foil, and cured, followed by lamination of the uncoated surface of the carrier foil to the surface of the structure to be provided with anti-smudge and/or stain release properties, for example by use of an adhesive.

In order to achieve good adhesion to the substrate, the coating composition is preferably applied to the substrate with a primer layer and/or a tie coat layer. The primer layer may be deposited from any primer composition known in the art, such as epoxy-based or polyurethane-based primer compositions. Preferably, the tie coat deposited from the tie coating composition is provided to the substrate prior to application of the coating deposited from the coating composition of the present invention. The tie coat composition may be applied to a bare substrate surface, a primed substrate surface, or a substrate surface comprising an existing layer of the anti-smudge or anti-smudge coating composition.

It has been found that the coating deposited from the coating composition of the present invention provides excellent adhesion to a tie coating deposited from a tie coating composition comprising a binder polymer having alkoxysilyl or alkoxyalkyl silyl functional groups. The tie-coat composition is a solvent-based composition in which a binder polymer having curable alkoxysilyl or alkoxyalkyl silyl functional groups is dissolved in an organic solvent and contains less than 10 wt.% water, preferably less than 5 wt.% water, more preferably less than 1 wt.% water. In one embodiment, the tie coating composition is substantially free of water.

The binder polymer having curable alkoxysilyl or alkoxyalkyl silyl functional groups in the tie-coat composition can be any suitable binder polymer, for example, a polyurethane, polyurea, polyester, polyether, polyepoxy resin, or a binder polymer derived from ethylenically unsaturated monomers such as (meth) acrylic monomers. Such binder polymers are known in the art and are described, for example, in WO 99/33927.

Preferably, the binder polymer is a poly (meth) acrylate having curable alkoxysilyl or alkoxyalkyl silyl functional groups. The binder polymer may be obtained by free radical polymerization of a mixture of (meth) acrylic monomers including (meth) acrylic monomers having a curable alkoxysilyl or alkoxyalkyl silyl functional group, preferably as described above for monomer b, and hydrophobic (meth) acrylic monomers free of crosslinkable groups, in particular as described above for monomer c. Preferably, the monomer mixture comprises less than 25 wt%, more preferably less than 10 wt%, even more preferably less than 5 wt% of any (meth) acrylic monomer described above for monomer a. or any other hydrophilic (meth) acrylic monomer, such as (meth) acrylic acid, hydroxy-functional, alkoxy-functional, zwitterionic or salt-group-containing (meth) acrylic monomer. In one embodiment, the monomer mixture is substantially free of hydrophilic (meth) acrylic monomers selected from the group consisting of monomers a., (meth) acrylic acid, hydroxy-functional, alkoxy-functional, zwitterionic, and salt-containing groups as described above.

An example of a monomer mixture for the binder polymer in a tie-coat composition is a mixture comprising methyl methacrylate, lauryl methacrylate and trimethoxysilylmethyl methacrylate or trimethoxysilylpropyl methacrylate.

Preferably, the binder polymer in the tie coating composition has no crosslinkable functional groups other than alkoxysilyl or alkoxyalkyl silyl functional groups.

The tie coat composition comprises an organic solvent. The solvent is preferably a solvent in which the base polymer is prepared by radical polymerization. Thus, solvents in which both the monomer and the binder polymer are dissolved are preferred. Examples of suitable solvents include ketones such as methyl n-amyl ketone (MAK), Methyl Ethyl Ketone (MEK), methyl isobutyl ketone (MIBK), methyl isoamyl ketone (MIAK), and hydrocarbon solvents such as xylene, toluene, trimethylbenzene. Methyl-n-amyl ketone is a particularly preferred solvent. The tie-coat composition may comprise up to 50 wt%, preferably 10-40 wt%, more preferably 20-35 wt% of solvent.

To prevent the tie coat from deforming or wrinkling after immersion in water, it is preferred that the tie coat composition is at least partially cured prior to application of the aqueous coating composition of the present invention. Thus, the tie coating composition preferably comprises a silanol condensation catalyst such that if dried for several hours before application of the coating composition of the present invention, the tie coating composition will at least partially cure. Suitable silanol condensation catalysts are known in the art and include carboxylates of various metals such as tin, zinc, iron, lead, barium and zirconium, for example dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dioctoate, iron stearate, tin (II) octoate and lead octoate; an organobismuth compound; an organic titanium compound; organic phosphates such as di (2-ethylhexyl) hydrogen phosphate; chelates, such as dibutyltin acetylacetonate; tertiary amines, for example 1, 8-diazabicyclo (5.4.0) undec-7-ene (DBU). The silanol condensation catalyst can be used in any suitable amount, typically from 0.1 to 2 weight percent based on the tie-coat composition.

In a preferred embodiment, the substrate is coated with a multi-layer coating system, optionally comprising a primer layer applied to the substrate and deposited from a primer coating composition, and further comprising a tie coat layer deposited from a tie coating composition comprising a binder polymer having curable alkoxysilyl or alkoxyalkyl silyl functional groups, applied to the substrate or optional primer layer, and a topcoat layer applied to the tie coat layer, wherein the topcoat layer is deposited from the coating composition of the first aspect of the invention.

In a third aspect, the present invention provides a method of controlling biofouling on a surface of an artificial object, comprising the steps of:

(a) applying the aqueous coating composition of the first aspect of the invention to at least a portion of the surface of a man-made object;

(b) curing the coating composition to form a cured coating; and

(c) at least partially immersing the man-made object in water.

Preferably, the method further comprises the step of applying a tie coating layer onto at least a portion of the surface of the man-made object prior to applying the coating composition of step (a), wherein the tie coating layer is deposited from a tie coating composition comprising a binder polymer having curable alkoxysilyl or alkoxyalkyl silyl functional groups as described above. In a particularly preferred embodiment, the tie coating composition comprises a silanol condensation catalyst and is allowed to partially cure prior to application of the aqueous coating composition.

The invention is further illustrated by the following non-limiting examples.

Examples

Preparation of acrylic Polymer solution

An acrylic polymer solution was prepared from the monomer mixture as follows. A solution of the monomer mixture and initiator (AMBN) in 1-methoxypropan-2-ol was added dropwise at 95 ℃ to a polymerization vessel containing 1-methoxypropan-2-ol using a peristaltic pump. The monomer solution was added at a rate that took 4 hours. After the end of the addition, the accelerator of the initiator in 1-methoxypropan-2-ol was added and the reactor was kept at 95 ℃ for 1 hour, after which the polymer solution was cooled to room temperature. The resulting polymer solution had 65 wt% of an acrylic polymer.

As described above, various solutions of acrylic polymers were prepared using different monomer mixtures a to F. Table 1 shows the composition of the monomer mixture used and the Fox calculated glass transition temperature (Tg) of the resulting acrylic polymer.

TABLE 1 composition of monomer mixture and Tg of acrylic Polymer

^aMPEGMA: methoxy poly (ethylene glycol) methacrylate (Bisomer MPEG350 MA)

^bTMSPMA: trimethoxysilylpropyl methacrylate

^cComparative examples

Preparation of Tie-coat compositions

Alkoxysilyl-functional polyacrylates are prepared by copolymerizing a mixture of methyl methacrylate, lauryl methacrylate and trimethoxysilylpropyl methacrylate in the presence of mercaptopropyltrimethoxysilane as chain transfer agent and 2,2' -azobis (2-methylbutyronitrile) (AMBN) as initiator in methyl-n-amyl ketone (MAK) as solvent at 100 ℃. The molar ratio of methyl methacrylate/lauryl methacrylate/trimethoxysilylpropyl methacrylate/mercaptopropyltrimethoxysilane was 70/12/15/3. A 70 wt% solution of the polymer in MAK was obtained.

Example 1 biofilm removal test 1

The coating composition of the invention was prepared by diluting the polymer solution obtained from monomer mixture B with water until a polymer concentration of 25% by weight was obtained (composition B).

The dirt-removing properties of the coatings deposited from composition B were determined and compared with commercially available coatings as a non-dirt-removing referencePolysiloxane-based stain release coating (Intersleep)^TM1100SR from Akzo Nobel) and a commercially available epoxy-based primer (Intershield)^TM300, obtained from akzo nobel).

The coating composition was applied to 75mm x 25mm x 2mm Plastic (PVC) test specimens and the coated substrate was immersed in an aquatic environment known to be subject to marine biofouling (Hartlespool Marina, uk). After 4 weeks of immersion, the samples were removed and tested for biofilm removal in a variable speed hydrodynamic flow cell. The fouled sample was mounted in a flow cell and the fully turbulent seawater was passed over the surface. The water flow rate was increased incrementally and held constant at each rate for 1 minute. Before each speed increase, slides were imaged and the amount of biofilm remaining on the surface as a percentage of the total area (% coverage) was evaluated using image analysis software (ImageJ, version1.46r, Schneider et al, 2012). The percent coverage of biofilm was the average of 6 replicate slides and the average percent coverage between surfaces at each speed was compared. The results are shown in Table 2.

TABLE 2 biofouling coverage (in%) at different flow rates

Example 2 biofilm removal test 2 (slime farm test)

The coating composition of the present invention was prepared by diluting the polymer solution obtained from monomer mixtures C, D, E and F with water until a polymer concentration of 25 wt% was obtained (compositions C, D, E and F), followed by the addition of 1 wt% DBU as catalyst.

Compositions C, D, E and F and Intersleek, determined in a so-called slime farm test^TMFouling release performance of 1100SR deposited coatings. The coating composition was applied to a 75mm by 25mm by 2mm Plastic (PVC) test specimen. The coated samples were placed in a recirculating reactor of a polytype slime culture system. This is a recirculating artificial seawater system (temperature 22. + -. 2 ℃, salinity 33. + -. 1psu (actual salinity unit), pH 8.2± 0.2) inoculated with a multi-species culture of wild microorganisms. The system simulates a subtropical environment whereby a marine biofilm is cultured and subsequently grown on a coated test surface under controlled hydrodynamic and environmental conditions under accelerated conditions. After 4 weeks, samples were removed and tested for biofilm removal in the variable speed hydrodynamic flow cell described in example 1, with results shown in table 3.

TABLE 3 biofouling coverage (in%) at different flow rates

The results of tables 2 and 3 show that the coating compositions of the present invention exhibit reasonable stain release properties while being less expensive and having fewer staining problems than polysiloxane-based coating compositions.

Example 3 drying time, pot life and shelf life with and without catalyst

The coating composition of the present invention was prepared by diluting the acrylic polymer solution prepared from monomer mixtures a and B with water until a polymer concentration of 20 wt% or 25 wt% was obtained. A silanol condensation catalyst is added to some coating compositions.

The time until the coating composition applied to the glass test panel at a wet film thickness of 300 μm is touch-dry or hard-dry is determined according to ASTM D-1640/D1640M-14((2018)), method A (at 23 ℃ and 50% relative humidity) using a BK dry adhesion recorder.

For some coating compositions with catalysts, the pot life or shelf life was determined as follows.

Pot life was determined by mixing the coating composition and catalyst in a 20ml vial. Immediately after mixing, the viscosity was measured using Sheen CP1 cone-plate viscometer. The vials were stored at 23 ℃ and the viscosity was measured periodically. Pot life is defined as the time at which the viscosity increases 1.5 times the initial value.

Shelf life was determined by mixing the coating composition and catalyst in a 20ml vial and storing the vial at 45 ℃. After 1, 2 and 3 days, then after 1, 2 and 3 weeks, and monthly thereafter, the viscosity was measured using Sheen CP1 cone-plate viscometer. Shelf life is defined as the time until the composition gels.

Coating compositions comprising DBU as silanol condensation catalyst show long pot life and, if diluted to a polymer concentration of 20 wt%, significantly long shelf life.

TABLE 4 drying time, pot life and shelf life of coating compositions with and without catalyst

Example 4 adhesion to primer and Tie coat after seawater immersion

The coating composition of the present invention was prepared by diluting the polymer solution obtained from the monomer mixture a with water until the polymer concentration reached 25% by weight. Then, 1 wt% of DBU was added as a silanol condensing catalyst.

The coating compositions thus obtained were applied to various base coats deposited from various primer or tie-coat compositions, and the adhesion strength of the coatings to the base coats after seawater immersion was determined as follows.

A30 cm by 8cm by 2cm PVC test panel was surface roughened using sandpaper and then degreased with a solvent. Portions of the panels were then brushed with a base coat and dried at 23 ℃ and 50% relative humidity. The coating composition of the invention was then applied using a 300 μm Sheen cube applicator and dried for 3 days at 23 ℃ and 50% relative humidity. The test panels were then immersed in natural seawater (conductivity 42.6mS/cm) at 22 ℃. After 6 days, the adhesion between the base coat and the topcoat was evaluated qualitatively by cutting through the coating to the substrate using a small blade and removing a small portion. Rubbing the exposed part with a finger, the adhesion between the base coat and the top coat layer gave a rating of 0 (very poor adhesion) to 5 (very good adhesion).

The following primer layers were used:

-RingOxygen primer: intershield^TM300, and drying for 24 hours.

Tie-coat composition 1: the tie-coat composition, prepared as described above in "preparation of tie-coat composition", was dried for 6 hours.

Tie-coat composition 2: a tie-coat composition 1 with 0.025 wt% di-2- (ethylhexyl) hydrogen phosphate as catalyst was added just prior to application and dried for 6 hours.

TABLE 5 adhesion to undercoating after seawater immersion

Experiment of	Base coat	Adhesion rating	Evaluation of
				17	Epoxy primer	3	Without wrinkling
18	Tie-coat composition 1	5	Cured tie-coat creping
				19	Tie-coat composition 2	5	Without wrinkling

Example 5 comparative example

Example H is insoluble in water.

Example G was dissolved in water at concentrations of 20 wt% and 25 wt%. Then 1 wt% DBU was added.

The 25 wt% solution gelled within 2 minutes.

The 20 wt% solution was applied to a PVC substrate with a base coat of tie coat composition 2 (see example 4 above).

Polymer a of example 14 above was also applied to a PVC substrate with a base coat of tie coat composition 2.

The two coated substrates were then immersed in seawater according to the procedure detailed in example 4 above, except that the duration was 24 hours instead of 6 days.

The composition comprising comparative polymer G (with high mpeg ma monomer content) showed delamination and also severe blistering and blistering of the coating, whereas these defects were not observed in the composition comprising polymer a.