WO2024168795A1

WO2024168795A1 - Composition

Info

Publication number: WO2024168795A1
Application number: PCT/CN2023/076714
Authority: WO
Inventors: Jianping Wu; Dongping LIU; Zhenzhen Zhang; Jia Zhao
Original assignee: Jotun A/S
Priority date: 2023-02-17
Filing date: 2023-02-17
Publication date: 2024-08-22

Abstract

The present invention relates to a coating composition, preferably a primer, comprising: (i) epoxy-based binder; (ii) epoxy silane, wherein said epoxy silane comprises ethoxy groups and methoxy groups; (iii) zinc, preferably zinc dust; (iv) curing agent; and (v) preferably aminoalkyl alkoxy silane, wherein said composition has a solids content of at least 75 %by volume, and a VOC content of 10 %wt or less.

Description

Composition

INTRODUCTION

The present invention relates to a coating composition, preferably a primer composition, as well as to a method and a kit for preparing the composition. The invention further relates to a container containing the composition, to a method of providing a coating on a surface comprising applying the composition, and to a coating on a surface which comprises, or derives from, the composition. Additionally, the invention relates to a use of a composition as herein described to form a coating on at least one surface of an article.

BACKGROUND

There is a growing need to provide paint with low or no Volatile Organic Compounds (VOCs) . This is driven by Government regulations requiring manufacturers to find green solutions that reduce the amount of VOCs in their products, and also by consumer desire to adopt environmentally friendly products.

To date, there are no low VOC epoxy zinc rich primers commercially available on the market. Zinc rich primers are those forming a coating with a zinc dust pigment content equal to or greater than 80 %by mass in the dry coating. Primers comprising zinc dust have anti-corrosion properties. Such coatings are used extensively in, e.g. the marine and oil and gas industries, where coatings are constantly exposed to atmospheric corrosive environments, e.g. up to corrosive category C5 according to ISO 12944-2: 2017. Anti-corrosive coatings are commonly used on inter alia bridges, fencing, refinery equipment, pipes, power plants, storage tanks, containers, windmills, turbines, and steel structures forming parts of buildings (e.g. airports, museums, sports arenas) .

In zinc dust-containing coatings, the zinc dust functions as a conductive pigment to provide anodic protection, i.e. zinc dust acts as a sacrificial anode and prevents the metal substrate that it protects from anodising. The anodic protection provided by zinc dust in zinc-containing coatings relies on the flow of current in the coating, and therefore on the presence of sufficient zinc to support current flow. Conventionally zinc dust in anti-corrosive coatings is packed closely together and is present in a high weight percent to ensure this is achieved.

The presence of relatively high amounts of zinc dust in coating compositions (e.g. 50-80 wt%is typical) can be problematic. The presence of relatively high amounts of zinc in the coating composition increases its density and can cause settling during storage. Zinc from coatings can also leach into the environment which is harmful.

Epoxy zinc rich primers are required to satisfy a number of requirements including:

· At least 80 %wt zinc dust in the dried film (i.e. paint) (comply with ISO 12944-5: 2019 requirement)

· Storage stability

· Be applicable with conventional airless spray equipment

· Drying, and curing, to a dry state within 6 hours at 23 ℃

· Low shrinkage upon cure

· Excellent anticorrosive performance, e.g. should pass condensation exposure test for at least one month, and salt spray test for at least two months (comply with ISO 12944-6: 2018 C5 high requirement)

· Be compatible with various epoxy primers as midcoats

Additionally, to meet the various environmental protection regulations already in place, and/or likely to implemented in the coming years, the volume solids of the composition should be at least 80 %and the VOC weight ratio should be less than 10 %wt.

However, it has proven difficult to prepare an epoxy zinc rich primer with a high volume solids, and which retains its applicability. Epoxy and amine curing agents that are used to make these primers are viscous, making it difficult to develop compositions with low viscosity, and correspondingly high applicability. As a result, conventional epoxy zinc rich primers typically have a volume solid of around 60 %. When the volume solid is further increased, and VOCs decreased, the viscosity of the composition increases and it becomes difficult to apply. Furthermore, it is impossible to prepare relatively thin coatings as required for certain applications, with highly viscous compositions. This is because the viscous composition has poor flow and levelling properties, and thus a relatively higher wet film thickness is needed to evenly cover the substrate. Correspondingly, this results in a relatively thick dry film thickness, typically up to above 90 μm. (For contrast, the typical dry film thickness of epoxy zinc rich primers is only around 60-70 μm) .

Another problem with the high content of zinc rich compositions (above 80%) is they typically have poor storage stability, because the zinc dust density is very high (7.1g/cm³) and zinc dust settles as a consequence. Typically, thixotropic agents are added to try to achieve stability in these circumstances.

To try to overcome the drawbacks of commercially available epoxy zinc rich primers, it is known to add one or more reactive epoxy diluents to the composition. This has the effect of reducing the viscosity of the composition, and therefore improves its applicability as well as its ability to form relatively thin coatings. However, the addition of reactive epoxy diluent to the composition also has disadvantages. For example, it tends to negatively impact on the anticorrosive performance of the coating, as well as on its adhesion to substrates. It is also common for compositions comprising reactive epoxy diluents to have unacceptably long drying times, and to result in the formation of soft films. Hence adding reactive epoxy diluents into epoxy zinc rich primer compositions is not an ideal solution.

SUMMARY OF INVENTION

Viewed from a first aspect, the present invention provides a coating composition, preferably a primer, comprising:

(i) epoxy-based binder;

(ii) epoxy silane, wherein said epoxy silane comprises ethoxy groups and methoxy groups;

(iii) zinc, preferably zinc dust;

(iv) curing agent; and

(v) preferably aminoalkyl alkoxy silane

wherein said composition has a solids content of at least 75 %by volume, and a VOC content of 10 %wt or less, based on the total volume and weight of the composition respectively.

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

(i) epoxy-based binder;

(iii) zinc, preferably zinc dust;

(iv) curing agent; and

(v) preferably aminoalkyl alkoxy silane.

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

(i) a first container containing epoxy-based binder, epoxy-silane, wherein said epoxy silane comprises ethoxy groups and methoxy groups and zinc, preferably zinc dust; and

(ii) a second container containing curing agent and preferably aminoalkyl alkoxy silane .

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

Viewed from a further aspect the present invention provides a method of providing a coating on a surface, wherein said method comprises:

(i) applying a composition as hereinbefore described; and

(ii) drying and/or curing said composition to form a coating on the surface.

Viewed from a further aspect, the present invention provides a coating on a surface, wherein said coating comprises, or derives from, a composition as hereinbefore described.

Viewed from a further aspect, the present invention provides use of a composition as hereinbefore defined to form a coating on a least one surface of an article.

DEFINITIONS

As used herein the term “Volatile Organic Compounds” refers to compounds having a boiling point ≤ 250℃ at 101.3 kPa. This is the definition given in EU Directive 2004/42/CE.

As used herein the term “coating composition” refers to a composition that, when applied to a surface, forms a film or coating thereon.

As used herein the term “primer” refers to a composition that is applied directly on to the surface of an article, i.e. without prior application of another coating. Typically, another composition is applied on top of the primer.

As used herein the term “binder” refers to a polymer which forms a continuous film on a substrate surface when applied thereto. The other components of the composition are dispersed throughout the binder.

As used herein the term “epoxy-based” refers to a polymer or oligomer comprising epoxy groups and/or modified epoxy groups. The term epoxy-based binder encompasses binders that have the traditional epoxy backbone (i.e. the same backbone as corresponding epoxy resins, e.g. a bisphenol based backbone) but where epoxy end-groups are modified with, e.g. acrylic or methacrylic functional groups that can be cured with the same curing agents as the epoxy groups. Often the epoxy binder will comprise at least some epoxy groups. The term epoxy is used interchangeably with epoxide.

As used herein the term “liquid epoxy resin” refers to an epoxy polymer that is liquid at ambient temperature and pressure (25 ℃ and 1 atm) . The term “liquid” refers to the physical state of the epoxy-based binder.

As used herein the term “epoxy” refers to a three-atom cyclic ether.

As used herein the term “epoxy binder system” refers to the combination of epoxy resin (s) and curing agent (s) , accelerators and optionally reactive diluents.

As used herein, the phrase “equivalent epoxy weight” or “EEW” refers to the grams of epoxy functional compound (epoxy binder) equivalent to 1 mol of epoxy groups. It is determined according to ASTM D1652.

As used herein the term “AHEW” refers to the “Amine hydrogen equivalent weight” , which is the mass of curing agent (compound comprising (re) active amine hydrogens) in grams equivalent to 1 mol of active amine hydrogens. It may be determined by potentiometric titration (ISO 9702: 1996) .

As used herein “curable at ambient temperature” refers to a coating composition that, following application to a substrate, is capable of curing in the presence of ambient air. Generally the air will have a relative humidity of 10-100 %, e.g. 15 to 78 %. Generally the air will have a temperature of 5-50 ℃, preferably 5-40 ℃, more preferably 10-35 ℃, e.g. 15-30 ℃.

As used herein the term “cure” refers the process by which crosslinkable components of the composition are at least partially crosslinked, and preferably are crosslinked. One skilled in the art will understand that the presence and degree of cross linking is evidenced by some of the properties of the coating.

As used herein the term “curing agent” refers to a compound which, when mixed with the epoxy resin, produces a cured or hardened coating by generating cross-links within the polymer. Typically the curing agent is the compound which supplies the reactive hydrogen that is transferred to an epoxide of the binder in the epoxy ring opening reaction. More specifically, in the compositions herein, the curing agent co-polymerises with the epoxy resin, and due to the multi-functionality of the curing agent, creates a polymer network. Sometimes curing agents are referred to as hardeners.

As used herein the terms “curing accelerator” and “accelerator” are used synonymously and refer to compounds which increase the rate of the curing reaction to cure or harden the coating.

As used herein the term “epoxy silane” refers to a compound that comprises at least one epoxy group and at least one silane group.

As used herein the term “spherical” , when used in relation to particles, e.g. zinc or glass particles, encompasses substantially spherical and spherical particles. Substantially spherical particles are identical in size in each of the x, y and z dimensions, ± 1.2 μm, more preferably ± 0.6 μm.

As used herein the term “average diameter” refers to the median diameter size (D₅₀) as determined by ISO 13320: 2009 using a Malvern Mastersizer 2000.

As used herein the term D₅₀ refers to the diameter at which 50%of the distribution of particles has a smaller particle size and 50%of the distribution has a larger particle size.

As used herein the term D₉₉ refers to the diameter at which 99%of the distribution has a smaller particle size and 1%has a larger particle size. Other D values follow the same pattern. For example, as used herein the term D₈₈ refers to the diameter at which 88%of the distribution has a smaller particle size and 12%has a larger particle size.

As used herein the term “dust” refers to spherical particles having an average diameter in the range 3 to 20 μm. Dust is therefore a type of particle, specifically relatively small particles.

As used herein the term “powder” refers to spherical particles having an average diameter in the range 21 to 100 μm. Powder is therefore a type of particle which is larger than dust.

As used herein the term “weight % (wt%) ” , when used in relation to individual constituents of the composition refers to the actual weight of constituent, i.e. without volatile components present, unless otherwise specified.

As used herein the term “weight % (wt%) ” , when used in relation to the coating compositions, refers to the weight relative to the total weight of the composition, i.e. including non-volatile and volatile components, unless otherwise specified.

As used herein the term “weight % (wt%) ” , when used in relation to the dry coating refers to the weight relative to the total weight of the dry coating, i.e. excluding the volatile components, unless otherwise specified.

As used herein the term “volume % (vol%) ” , when used in relation to the coating composition refers to the volume relative to the total volume of the composition.

As used herein the term “molecular weight” refers to weight average molecular weight (Mw) , unless otherwise specified. It is determined by Gel Permeation Chromatography.

As used herein the term “density” refers to density as determined by the pycnometer method (ISO 2811-1: 2016) .

As used herein the term “pigment volume concentration (PVC) ” refers to the ratio of the volume of pigment and other solids particles in a composition to the total volume of the non-volatile matter.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a coating composition, preferably a primer composition, comprising:

(i) epoxy-based binder;

(iii) zinc, preferably zinc dust;

(iv) curing agent; and

(v) preferably aminoalkyl alkoxy silane,

Optionally the coating composition of the present invention further comprises: (vi) filler, e.g. microspheres; (vii) rheology modifier; (viii) levelling agent; (ix) defoaming agent; (x) dispersing agent; (xi) other binder; (xii) solvent; and/or (xiii) additives.

The coating composition of the present invention is advantageously an epoxy zinc primer composition with a relatively high solids content, i.e. at least 75 %by volume, and a VOC content of 10 %wt or less, whilst retaining the key properties of providing coatings with strong anti-corrosive performance and being of sufficiently low viscosity to enable application by conventional techniques, e.g. airless spray gun. The desirable viscosity of the coating composition of the invention also means it can be used to prepare relatively thin coatings, e.g. coatings with a wet film thickness of approximately 60 microns.

Additionally the compositions of the present invention are stable to storage, e.g. their viscosity does not change significantly on storage and/or the zinc present therein does not settle. As mentioned above, this is a particular challenge encountered with this type of composition. The coating composition of the invention also has desirable drying, and curing, time. Thus a typical coating composition of the invention is through dried within 6 hours at 23 ℃.

Epoxy based binder

In the coating composition of the present invention, the binder is epoxy-based, and preferably epoxy. The epoxy-based binder may be a modified epoxy-based binder. Optionally the epoxy-based binder is modified with fatty acids, polypropylene oxide and/or polyethylene oxide.

The coating composition of the present invention may comprise one or more epoxy-based binders (e.g. epoxy binders) . A preferred coating composition comprises 1, 2 or 3 epoxy-based binders, e.g. epoxy binders, most preferably one epoxy-based binder, e.g. one epoxy binder.

Preferred epoxy-based binders, e.g. epoxy binder, present in the coating composition of the present invention have an equivalent epoxy weight (EEW) of 100-1000 g/eq, more preferably 120 to 500 g/eq, still more preferably 150-270 g/eq and yet more preferably 160-200 g/eq.

The epoxy-based binder, e.g. epoxy binder, is preferably a liquid epoxy-based binder. The liquid epoxy-based binder preferably has an epoxy equivalent weight (EEW) value of 100 to 1000 and more preferably 120 –500 g/eq. More preferred epoxy-based liquid binders have an EEW of less than 500 g/eq. The viscosity of the liquid epoxy-based binder is preferably 1000 –7500 mPas, more preferably 1500 –6000 mPas and still more preferably 2000 –5000 mPas.

Preferred epoxy-based binders comprise more than one epoxy group per molecule. Such 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.

It should be understood that the epoxy-based binders of the present invention encompass binders that have the traditional epoxy backbones (i.e. the same backbone as corresponding epoxy resins, e.g. a bisphenol based backbone) but where the epoxy end-groups have been modified with acrylic or methacrylic functional groups that can be cured with the same curing agents as the epoxy-groups. In these epoxy-based binders, the end-groups are preferably functionalised with acrylic and/or methacrylic functional groups.

Preferably the coating compositions of the present invention comprise one or more epoxy-based binders (e.g. epoxy binder) selected from aromatic or aliphatic epoxy-based binders.

Representative examples of suitable aliphatic epoxy-based binders include epoxy, and modified epoxy, binders selected from cycloaliphatic epoxy such as hydrogenated bisphenol A, dicyclopentadiene based binders, glycidyl ethers such as polyglycidyl ethers of polyhydric alcohols, epoxy functional acrylic resins or any combination thereof.

Representative examples of suitable aromatic epoxy-based binders include epoxy and modified epoxy binders selected from bisphenol type epoxy-based binders such as bisphenol A, bisphenol F and bisphenol S, novolac type epoxy-based binders such as phenolic novolac type binders (bisphenol A novolac, ) and cresol novolac type binder or any combinations thereof.

Preferably the one or more epoxy-based binders are selected from aromatic epoxy-based binders. 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.

Particularly preferred epoxy-based binders are bisphenol epoxy binders. Examples of such epoxy-based binders are bisphenol A epoxy-based binder, bisphenol F epoxy-based binder and bisphenol A/F epoxy-based binder. The bisphenol based epoxy binder may be a modified binder. Such modification may be fatty acid modifications or polyether modifications by reacting in segments of polyethylene oxide or polypropylene oxide.

Particularly preferably the epoxy-based binder is a bisphenol F epoxy-based binder. Still more preferably the epoxy-based binder is an unmodified liquid bisphenol F based epoxy resin. This epoxy-based binder is preferred because it has a particularly low viscosity, and gives rise to coatings with excellent adhesion, and anticorrosion performance.

Preferably the bisphenol based epoxy binder has an epoxy equivalent weight (EEW) of 150 –270 g/eq, and more preferably 160 –200 g/eq.

Examples of suitable commercially available epoxy based binders for use in the compositions of the present invention are:

- Bisphenol A type epoxy-based binders: D.E.R. 331 and D.E.R. 332 from Olin Epoxy

- Bisphenol F epoxy based binders: Epikote 862 from Hexion, D.E.R. 354 from Olin Epoxy.

- Mixture of bisphenol A and bisphenol F epoxy based binders: D.E.R. 352 from Olin Epoxy, Epikote 235 from Hexion.

The solids content of the epoxy-based binder is preferably more than 70 wt%, preferably more than 80 wt%, preferably more than 90 wt%, most preferred more than 99 wt%, based on the total weight of the binder. Preferably the epoxy-based binder is 100 wt%solids, i.e. solvent free.

The total amount of epoxy-based binder present in the coating composition of the present invention is preferably 3-15 wt%, more preferably 5-10 wt%, and still more preferably 6-8 wt%based on the total weight of the composition. If a blend of epoxy-based binder is used then these percentages refer to the total content of epoxy-based binder.

Epoxy silane

Epoxy silane, wherein said epoxy silane comprises ethoxy groups and methoxy groups

The coating composition of the present invention comprises one or more epoxy silanes. Preferably the coating composition comprises a mixture of epoxy silanes, e.g. two or three, preferably two, epoxy silanes.

Epoxy silanes are not generally stable in zinc rich epoxy compositions and it is hypothesized that they gradually undergo hydrolysis with water introduced via other ingredients to generate silanols. Gelation of these silanols causes an undesirable increase in viscosity. It has now been found that ethoxy-containing epoxy silanes are more stable than methoxy-containing epoxy silanes, hence their presence improves storage stability. On other hand, the methoxy-containing epoxy silanes improve drying and curing speed. The presence of a mixture of epoxy silanes, comprising methoxy and ethoxy groups, has been found to provide a desirable balance of drying and curing speed, as well as storage stability. This is particularly the case when an aminoalkyl alkoxy silane is additionally present.

In the coating composition of the present invention the epoxy silane is preferably a 3-glycidoxyalkylalkoxysilane, and more preferably a 3-glycidoxypropylalkoxysilane. Yet more preferably the epoxy silane is a 3-glycidoxyalkyl tri, di or monoalkoxy silane, and still more preferably a 3-glycidoxypropyl tri, di or monoalkoxy silane.

In the coating composition of the present invention the epoxy silane is preferably of formula (I) :

wherein

n is an integer from 1 to 6;

R is C1-12 alkyl;

each R^a is independently methyl or ethyl; and

b is an integer from 1 to 3.

In preferred epoxy silanes of formula (I) , n is 3, i.e. propyl.

In further preferred epoxy silanes of formula (I) , b is 2 or 3, particularly 3.

A coating composition of the present invention may comprise an epoxy silane of formula (I) wherein at least one R^a is methyl and at least one R^a ethyl.

More preferably the coating composition of the present invention comprises a mixture of epoxy silanes of formula (I) . Preferably the mixture comprises a first epoxy silane of formula (I) wherein R^a is methyl and a second epoxy silane of formula (I) wherein R^a is ethyl. In other words the coating composition comprises a mixture of epoxy silanes comprising methoxy and ethoxy groups.

Examples of preferred epoxy silanes present in the coating composition of the present invention include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyldimethylmethoxysilane, 3-glycidoxypropylethyldimethoxysilane, 3-glycidoxypropyldiethylmethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyldimethylethoxysilane, 3-glycidoxypropylethyldiethoxysilane, 3-glycidoxypropyldiethylethoxysilane and combinations thereof.

A particularly preferred coating composition of the present invention includes a first epoxy silane selected from 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyldimethylmethoxysilane, 3-glycidoxypropylethyldimethoxysilane, 3-glycidoxypropyldiethylmethoxysilane, and combinations thereof, and a second epoxy silane selected from 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyldimethylethoxysilane, 3-glycidoxypropylethyldiethoxysilane, 3-glycidoxypropyldiethylethoxysilane and combinations thereof. An especially preferred coating composition of the present invention comprises 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane.

In a preferred coating composition of the present invention the epoxy silane (s) present comprise methoxy groups and ethoxy groups in a mass ratio of 3: 1 to 1: 3, preferably 2: 1 to 1: 2 and more preferably about 1: 1.

Examples of such epoxy silanes are commercially available from, e.g. Evonik Industries AG, Momentive, and Wacker. Specific examples include 3- glycidoxypropyltrimethoxysilane (Dynasylan GLYMO, Silquest A-187) , and 3-glycidoxypropyltriethoxysilane (Dynasylan GLYEO) .

The total amount of epoxy silane in the coating composition of the present invention is preferably 1-10 wt%, preferably 1.5-7.5 wt%and still more preferably 2-5 wt%based on the total weight of the composition. If a blend of epoxy-silanes is used then these percentages refer to the total content of epoxy-silane.

Zinc

The coating composition of the present invention comprises zinc, and preferably comprises zinc dust. Preferred zinc dust present in the coating composition comprises at least 90 wt%zinc, such as at least 95 wt%, more preferably at least 97 wt%, and still more preferably at least 98 wt%zinc. The upper limit for the amount of zinc may be 100 wt%.

Preferably the zinc dust present in the coating composition of the present invention is substantially spherical. In preferred coating compositions the zinc dust has a particle size of 1-20 μm, more preferably 2-10 μm and still more preferably 3-7 μm, as measured by a Fisher sub sieve sizer, ASTM B330-07. Further preferred zinc dust has a particle size D₅₀ 1-20 μm, more preferably 2-10 μm and still more preferably 3-8 μm, and a D₉₀ of 5 to 30 μm, more preferably 6 to 20 μm and still more preferably 8 to 15 μm as measured by laser diffraction. The particle sizes of zinc dust referred to herein are the size of the particles when they are added to the composition and prior to any extrusion or milling process.

Preferred zinc dust present in the coating composition of the present invention has a bulk density of 1 to 3.5 g/cm³ and more preferably 2 to 3.0 g/cm³.

Preferred zinc dust present in the coating composition of the present invention has a specific gravity of 6 to 9 g/cm³ and more preferably 7 to 8 g/cm³ determined according to ISO 787-10 at 20 ℃.

Zinc dust for use in the coating composition of the present invention is commercially available. For example, it is available from Everzinc, Purity Zinc Metals, Umicore and others.

Optionally the coating composition of the present invention may comprise zinc in other forms, such as zinc flakes and/or zinc powder.

Zinc flakes are lamellar or plate-like in structure. Zinc flakes are typically produced from zinc dust by ball milling in non-reactive fluid such as a hydrocarbon. The milling results in each dust particle being flattened into flake form.

Zinc flakes differ from other forms of zinc, including zinc dust and zinc powder, in its aspect ratio and density. Preferred zinc flakes have an aspect ratio of 5: 1 to 60: 1, more preferably 10: 1 to 50: 1 and still more preferably 20: 1 to 40: 1.

When present in the coating composition, the zinc flakes are substantially planar. Preferred zinc flakes have a thickness of 0.1 to 5 μm, more preferably 0.2-2 μm and still more preferably 0.3-1 μm. Preferred zinc flakes have a thickness of less than 3 μm, e.g. 0.1 to 2.8 μm.

Zinc flakes that are suitable for use in the compositions of the present invention are commercially available from Eckart under the tradename Zinc Flake and ProFLAKE.

A preferred coating composition of the present invention does not comprise zinc flakes. A further preferred coating composition of the present invention does not comprise zinc powder. A yet further preferred coating composition of the invention does not comprise zinc flakes or zinc powder. In other words, it is preferred if all the zinc present in the coating composition is in the form of zinc dust.

The total amount of zinc present in the coating composition of the invention is preferably 65-90 wt%, more preferably 70-85 wt%and still more preferably 75-80 wt%, based on the total weight of the composition. The total amount of zinc dust present in the coating composition of the invention is preferably 65-90 wt%, more preferably 70-85 wt%and still more preferably 75-80 wt%, based on the total weight of the composition.

Curing agent

The coating composition of the present invention comprises a curing agent. Preferably the curing agent has a viscosity below 1500 mPas, more preferably below 1000 mPas, and still more preferably below 800 mPas. Preferably the curing agent has a viscosity of 50-1500 mPas, more preferably 75-750 mPas and still more preferably 85-700 mPas. The low viscosity of the curing agent helps to ensure that the overall viscosity of the coating composition is not too high.

Preferably the curing agent is selected from amine curing agents, polyamine curing agents, and/or amino functional polymer curing agents. Preferably the curing agent is a polyamine curing agent, i.. a curing agent comprising at least two amine groups.

To obtain a crosslinked network the curing agent must contain at least three "reactive" hydrogen atoms. The term “reactive” with reference to hydrogen atoms refers to a hydrogen atom that is transferred from a nucleophile to the oxygen atom of the epoxide during the ring opening reaction. Active amine groups in curing agents cannot therefore be tertiary. The curing agent preferably contains at least two curing reactive functional groups, and preferably at least two amine groups. The curing agent present in the coating composition of the present invention preferably has an AHEW of 70 –150 g/eq, more preferably 80 –130 g/eq, and still more preferably 90 –110 g/eq.

In a preferred coating composition of the present invention, the curing agent comprises at least one benzylamine motif:

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

The curing agent present in the coating composition of the present invention may comprise two or more repeating units, i.e. the curing agent may be 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 benzylamine 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. Suitable substituents are those described above.

A preferred curing agent present in the coating composition of the present invention comprises at least two or more benzylamine structures. More preferably the curing agent comprises a benzylated polyalkylene polyamine structure as described in WO2017147138A. Preferably the benzylated polyalkylene polyamine is of formula (II) :

wherein

R¹ is substituted or unsubstituted benzyl; each R² is independently selected from R¹ or a hydrogen atom or a group selected from C1 –C16 linear, cyclic or branched alkyl, alkenyl and alkylaryl groups;

X, Y and Z are independently selected from C2 –C10 alkylene and cycloalkylene groups, preferably ethylene, propylene, butylene, hexylene, cyclohexyldimethylene and cyclohexylene;

y is and integer from 1 –7; and

z is an integer from 0 –4

Suitable substituents for the benzyl group include C1-15 alkyl groups, OH, O-C1-4-alkyl, halogen, cyano, amine and alkyl amine groups (C1-4-N) .

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 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] diethylenetriamine; N, N'-bis (3-aminopropyl) -diethylenetriamine; N, N-bis (3-aminopropyl) diethylenetriamine; N, N, N'-tris (3-aminopropyl) diethylenetriamine; 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-aminopropyl] diethylenetriamine.

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 polyamine curing agent present in the coating composition of the present invention preferably has an AHEW of 70 –150 g/eq, more preferably 80 –130 g/eq, and still more preferably 90 –110 g/eq.

The total amount of curing agent present in the coating composition of the present invention is preferably 0.5-10 wt%, preferably 1-7.5 wt%and more preferably 2-4 wt%based on the total weight of the composition. If a blend of curing agents is used then these percentages refer to the total content of curing agent.

Curing accelerator

The coating composition of the present invention optionally comprises a curing accelerator. Generally, a curing accelerator increases the curing rate of the composition. For amine cured epoxy compositions, phenolic compounds, salts of strong acids, tertiary amine compounds, and acrylic esters are preferably employed as curing accelerators.

Phenolic compounds that may be suitable curing accelerators include 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 curing accelerators include triflate salts of the metals in group 2 of the periodic table such as Mg and Ca. Tertiary amine compounds suitable as curing accelerators are 3-aminopropyldimethylamine, benzyldimethylamine, 1, 4-diazabicyclo [2.2.2] octane, 1, 8-diazabicyclo [5.4.0] undec-7-ene, dimethylethanolamine, diethylethanolamine, triethanolamine, and 2, 4, 6-tris (dimethylaminomethyl) phenol (Ancamine K54 from Evonik) .

The total amount of curing accelerator in the coating composition of the present invention is preferably 0.05-1 wt%, preferably 0.1-0.5 wt%and more preferably 0.1-0.3 wt%based on the total weight of the composition. If a blend of curing accelerators is used then these percentages refer to the total content of curing accelerator.

Aminoalkyl alkoxy silane

The coating composition of the present invention preferably comprises an aminoalkyl alkoxy silane, preferably an aminopropyl alkoxy silane. The presence of aminoalkyl alkoxy silane typically improves the drying property of the composition, especially at low temperatures, as well as adhesion to substrates and anti-corrosive performance.

Preferably the aminoalkyl alkoxy silane present in the coating composition of the present invention is of low Mw, such as less than 400 g/mol.

Preferably the aminoalkyl alkoxy silane present in the coating composition of the present invention is of formula (IIIa) or (IIIb) :
A-R³ _(4-k) SiR⁴ _k (IIIa)
A-R³ _(3-p) SiR⁵R⁴ _p (IIIb)

wherein

A is an amine group bound to R³, and preferably A is NH₂;

R³ is a hydrocarbylene group having 1 to 12 C atoms optionally containing an ether or amino linker;

each R⁴ independently represents a C1-6 alkoxy group;

R⁵ is a hydrocarbyl group having 1 to 12 C atoms;

k is an integer from 1 to 3; and

p is an integer from 1 to 2, preferably 2.

In aminoalkyl alkoxy silanes of formula (IIIa) and (IIIb) the A group can bind to any part of the chain R³. Amino groups are preferably NH₂.

In aminoalkyl alkoxy silanes of formula (IIIa) and (IIIb) R⁴ is preferably a methoxy or ethoxy group and still more preferably a methoxy group. It is also especially preferred if there are two or three alkoxy groups present. Thus k is preferably 2 or 3, especially 3. Subscript p is preferably 2.

In aminoalkyl alkoxy silanes of formula (IIIa) and (IIIb) , R⁵ is preferably C_1-4 alkyl such as methyl.

In aminoalkyl alkoxy silanes of formula (IIIa) and (IIIb) R³ is a hydrocarbylene group having up to 12 carbon atoms. By hydrocarbylene 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 phenylene or cyclohexylene 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. It is preferred if the group A does not bind to a carbon atom which is bound to such a linker –O-or –NH-.

R³ might therefore represent - (C₆H₄) -NH- (CH₂) ₃-or (C₆H₄) - (CH₂) ₃ and so on.

R³ is preferably an unsubstituted (other than A obviously) , unbranched alkylene chain having 2 to 8 C atoms optionally containing an ether or amino linker.

Aminoalkyl alkoxy silanes of formula (IIIa) are generally preferred. In such compounds, preferably k is an integer from 2 to 3, R³ is an unsubstituted, unbranched alkylene chain having 2 to 8 C atoms optionally containing an ether or amino linker, A is an amino group bound to the R³ group, and R⁴ represents an alkoxy group, preferably methoxy or ethoxy.

Examples of suitable aminoalkyl alkoxy silanes are commercially available, e.g. from Evonik Industries AG, Momentive, and Wacker. Specific examples include 3-aminopropyltrimethoxysilane (Dynasylan AMMO; Silquest A-1110) , 3-aminopropyltriethoxysilane (Dynasylan AMEO) , N- (2-aminoethyl) -3-aminopropyltrimethoxysilane (Dynasylan DAMO, Silquest A-1120) , N- (2-aminoethyl) -3-aminopropyltriethoxysilane, triamino-functional 3- [2- (2-aminoethylamino) ethylamino] propyltrimethoxysilane (Silquest A-1130) , bis [3- (trimethoxysilyl) propyl] amine (Silquest A-1170) , N-ethyl-3-trimethoxysilyl-2-methylpropanamine (Silquest A-Link 15) , N-phenyl-3-aminopropyltrimethoxysilane (Silquest Y-9669) , 4-amino-3, 3-dimethylbutyltrimethoxysilane (Silquest Y-11637) , (N-cyclohexylaminomethyl) triethoxysilane (Geniosil XL 926) , (N-phenylaminomethyl) trimethoxysilane (Geniosil XL 973) , and Deolink Amino TE (D.O.G Deutsche Oelfabrik) and mixtures thereof. Further suitable aminoalky alkoxy silanes are available from Gelest, e.g. 4-aminobutyltriethoxysilane, 4-amino-3, 3-dimethylbutyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 4-amino-3, 3-dimethylbutylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldiethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-aminopropyldimethylethoxysilane and combinations thereof.

In the coating composition of the present invention 3-aminopropyltrimethoxysilane is preferred.

The total amount of aminoalkyl alkoxy silane present in the coating composition is preferably 0.05-5 wt%, preferably 0.1-2 wt%and more preferably 0.1-1.5 wt%based on the total weight of the composition. If a blend of aminoalkyl alkoxy silanes is used then these percentages refer to the total content of aminoalkyl alkoxy silane.

Reactive Diluent

The coating composition of the present invention optionally comprises a reactive diluent. Preferably the coating composition does not comprise a reactive diluent. This ensures a strong anti-corrosion performance.

When present, the reactive diluent preferably has a viscosity of <100 mPas, preferably <50 mPas, and more preferably <30 mPas at 23℃ and 50%RH, determined by the cone and plate method according to ISO 2884-1: 2006. This helps to lower the overall viscosity of the coating composition. The epoxy equivalent weight (EEW) of preferred reactive diluents is 100 to 500 g/eq, preferably 100 to 300 g/eq, and more preferably 120 to 170 g/eq.

When present, the reactive diluent is preferably formed from a modified epoxy compound. Preferably the reactive diluent is polyfunctional as opposed to monofunctional.

Examples of suitable reactive diluents that may be present in the coating composition of the present invention include phenyl glycidyl ether, alkyl glycidyl ether (number of carbon atoms in alkyl group: 1 to 16) , glycidyl ester of versatic acid (R⁴ R⁵ R⁶ C-COO-Gly, where R⁴ R⁵ R⁶ are alkyl groups such as C8 to C10 alkyl and Gly is a glycidyl group) , olefin epoxide (CH₃- (CH₂) n-Gly, wherein n=11 to 13, Gly: glycidyl group) , 1, 6-hexanediol diglycidyl 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 C1-20-alkylphenyl glycidyl ether (preferably C1-5 alkylphenylglycidyl ether) , e.g., methylphenyl glycidyl ether, ethylphenyl glycidyl ether, propylphenyl glycidyl ether and glycidyl neodecanoate. Another preferred option is Cardolite NC-513 derived from the reaction of epichlorohydrin and an oil obtained from the shells of cashew nuts. The use of p-TBPGE is also possible (para tertiary butyl phenyl glycidyl ether) .

Of the above reactive diluents, aliphatic reactive diluents are preferred. The aliphatic reactive diluents are preferably formed from the reaction of a compound comprising at least one aliphatic epoxide functionality with an aliphatic alcohol or polyol such as 1, 6-hexanediol diglycidyl ether or 1, 4-butanediol diglycidyl ether. Aliphatic glycidyl ethers of chain length 4 to 14 are particularly preferred. Aliphatic reactive diluents are generally preferred as they are believed to contribute to the flexibility of the coating.

When present, reactive diluents may be used singly or in combination, e.g. in combination of two or more diluents.

The total amount of reactive diluent in the coating composition is preferably 0-5 wt%, more preferably 0.1-4 wt%and still more preferably 0.5-3 wt%. If a blend of reactive diluents is used then these percentages refer to the total content of reactive diluent.

Filler

The coating composition of the present invention preferably comprises filler, and still more preferably microspheres. The presence of microspheres is advantageous to increase the volume solids of the composition, and decrease the VOCs.

The microspheres present in the coating composition of the invention are substantially spherical and more preferably spherical. This is advantageous as it allows the particles to pack more closely together in the coating composition of the invention. Alternatively viewed, the microspheres have a D₅₀ diameter of 10 to 100 μm, more preferably 20 to 80 μm and still more preferably 30 to 70 μm, as determined by ISO 13320: 2009 using a Malvern Mastersizer 2000.

Preferably the microspheres have a D₉₈ diameter of 55 to 190 μm, more preferably 75 to 170 μm and still more preferably 95 to 150 μm, as determined by ISO 13320: 2009 using a Malvern Mastersizer 2000.

The microspheres present in the coating composition may be organic or inorganic. Preferably the microspheres comprise and more preferably consist of glass, ceramic, or plastic. More preferably the microspheres in the coating compositions of the present invention comprise and still more preferably consist of a ceramic material or glass. Optionally the microspheres present in the coating compositions of the present invention may be surface treated. Optionally the microspheres may be coated or uncoated.

The microspheres may be hollow or solid, but are preferably hollow.

Examples of suitable inorganic microspheres are glass beads, or ceramic beads.

Examples of suitable organic microspheres include beads of polymer materials such as poly (methyl methacrylate) , poly (methyl methacrylate-co-ethylene glycol dimethacrylate) , poly (styrene-co-ethylene glycol dimethacrylate) , poly (styrene-co-divinylbenzene) , polystyrene, poly (vinyl chloride) , poly (vinylidene fluoride) and poly (vinylidene chloride) .

Preferably the coating composition of the present invention comprises solid or hollow, inorganic microspheres. Suitable solid or hollow, inorganic microspheres are commercially available. Examples include Glass Bubbles S28HS, Micro Bubbles H38HS, Fillite Cenosphere, Poraver (expanded glass) , Eccospheres, Q-Cel, Sphericel, Thermospheres, Omega shperes (availale from e.g. 3M, SMC Minerals, Omya, Poraver, Trelleborg, Potters, Omega) and hollow glass spheres from Hollowlite.

Preferably the coating composition comprises hollow, inorganic microspheres, such as cenospheres. This means the microspheres have a void or cavity in their centres. Preferred inorganic, hollow microspheres 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. This void or empty space is preferably filled with gas.

Preferably the microspheres have as low a density as practicable, e.g. the density of the microspheres might be 0.1-1 g/cm3, more preferably 0.2-0.9 g/cm3 e.g. as specified on the technical specification provided by suppliers. This may reflect the fact that the particles are hollow rather than solid.

Preferably the microspheres present in the coating composition of the present invention have an isostatic crush strength of at least 1500 psi, e.g. as specified by the supplier in the technical datasheet.

A preferred coating composition of the present invention comprises 2.0 to 10.0 wt%, more preferably 3.0 to 8.0 wt%and still more preferably 3.0 to 6.0 wt%microspheres, based on the total weight of the composition.

Rheology modifier

The coating composition of the present invention optionally comprise a rheology modifier. Sometimes rheology modifiers are also referred to as thixotropic agents. The presence of a rheology modifier may be beneficial for improving the storage stability, and/or the application properties, of the composition. For example a rheology modifier may be employed to prevent settling and floating, as well as to adjust levelling and improve sag resistance. Any conventional rheology modifier may be used. For example, organic rheology modifiers and/or inorganic rheology modifiers may be used. A single rheology modifier may be used or a combination thereof. Preferably a combination of two or three, e.g. two rheology modifiers is employed. A preferred coating composition of the present invention comprise an organic rheology modifier and an inorganic rheology modifier.

Representative examples of suitable organic rheology modifiers for use in the composition of the invention include amide waxes, castor oil derivatives, as well as rheology modifiers based on an acrylic, urea, modified urea, polyurethane, amide or polyamide backbones. The active constituents of the rheological modifier may be modified with functional groups such as for instance polyether and alcohol groups, or surface treated with for instance silanes. Amide wax is a preferred organic rheology modifier.

Representative examples of suitable inorganic rheology modifiers for use in the composition of the invention include fine powdered silica, bentonite, a surface treated silica, e.g. silane-treated silica, surface-treated bentonite, e.g. organically modified bentonite, surface-treated calcium carbonate, and mixtures thereof. Bentonite is a preferred inorganic rheology modifier.

Suitable rheology modifiers are commercially available, e.g. Bentone SD2 from Elementis, Crayvallac Ultra and Crayvallac LV from Arkema. Preferably the rheology modifier comprises a micronized amide wax based on castor oil derivatives and bentonite. Still more preferably the rheology modifier comprises a micronized amide wax based on castor oil derivatives and bentonite in a 1: 1 mass ratio.

The total amount of rheology modifier present in the coating composition of the invention is preferably 0-5 wt%, more preferably 0.2-3 wt%and still more preferably 0.3-2 wt%, based on the total weight of the composition. If a blend of rheology modifiers is used then these percentages refer to the total content of rheology modifier.

Levelling agent

The coating composition of the present invention optionally comprises a levelling agent. Sometimes levelling agents are also referred to as flow additives.

Any conventional levelling agent may be used. Acrylic levelling agents are generally preferred.

Representative examples of suitable levelling agents include BYK-350, BYK-355, BYK-356, BYK-358 N, BYK-359, BYK-361 N, and BYK-388, all available from BYK.

The amount of levelling agent present in the coating composition of the invention is preferably 0-5 wt%, more preferably 0.1-2.5 wt%and still more preferably 0.2-1.0 wt%, based on the total weight of the composition.

Defoaming agent

The coating composition of the present invention optionally comprises a defoaming agent. Defoaming agents are sometimes referred to in the art as air release additives.

Any conventional defoaming agent may be present in the coating composition of the invention. Common defoaming agents may be divided into mineral oil defoaming agents, silicon defoaming agents and polymer defoaming agents. Commercially available defoaming agents often contain a mixture of these types, often in combination with solvents and solid particles.

Non-limiting examples of commercially available defoaming agents that may be used in the composition of the present invention include 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-051 N, 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-A515, Byk-A525, Byk-A530, Byk-A535, Byk-A550, Byk-A555 and Byk-A560 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.

The amount of defoaming agent present in the coating composition of the present invention is 0 to 1.0 wt%, and more preferably 0.1 to 0.2 wt%, based on the total weight of the composition.

Dispersing and/or wetting agent

The coating composition of the present invention optionally comprises a dispersing agent. Often dispersing agents are referred to as wetting agents. Dispersing agents may be present in the coating composition to facilitate dispersion and wetting of the pigment and filler particles, thus making it easier to break up agglomerates during production, preventing re-flocculation and settling in wet compositions as well as formation of Bénard cells in curing coatings, reducing the compositions viscosity, and increasing its colour strength and colour stability.

The dispersing agent may be non-ionic, cationic, anionic or comprise a mixture of the afore-mentioned.

The dispersing agent may consist of polymers, or non-polymeric organic molecules or a mixture thereof.

Non-limiting examples of suitable types of dispersing agents include fatty acids, lecithins, polysorbates, polyacrylamides, polyethercarboxylates, polycarboxylates, polyalkylene glycols, polyethers, polyesters, phosphoric acid polyesters, and polyacrylates.

Non-limiting examples of commercially available dispersing agents that may be employed in the composition of the invention include Disperbyk-102, Disperbyk-106, Disperbyk-109, Disperbyk-110, Disperbyk-142, Disperbyk-161, Disperbyk-180, Disperbyk-182, Disperbyk-2000, Disperbyk-2014, Disperbyk-2055, Disperbyk-2059, Disperbyk-2070, Disperbyk-2152 from BYK, Colorol F from Evonik, Adlec soy lecithin and Yelkin soy lecithin from ADM.

The amount of dispersing agent present in the coating composition of the present invention is preferably 0 to 1.5 wt%, and more preferably 0.1 to 1 wt%, based on the total weight of the composition.

Binder

The coating composition of the present invention optionally comprises a binder (other than the epoxy-based binder) . This is referred to as a co-binder.

Examples of suitable co-binders include saturated polyester resins, polyvinylacetate, polyvinylbutyrate, copolymers of vinyl acetate, vinyl isobutyl ether, copolymers of vinyl chloride and vinyl isobutyl ether, styrene co-polymers such as styrene/butadiene co-polymers, acrylic resins, hydroxy-acrylate copolymers, fatty acids and cyclized rubbers.

The coating composition of the present invention preferably comprises 0-10 wt%co-binder, based on the total weight of the composition.

Solvent

The coating composition of the present invention optionally comprises a solvent. Suitable solvents include aromatic hydrocarbons, aliphatic hydrocarbons, ketones, esters, alcohols, and ethers.

Specific examples of suitable solvents are toluene, xylene, light aromatic solvent naphta (C8-C10, Solvesso 100) , mineral spirits, methyl ethyl ketone (MEK) , methyl isobutyl ketone (MIBK) , ethyl acetate, n-butyl acetate, isobutyl acetate, tert-butyl acetate, ethanol, isopropanol, n-propanol, n-butanol, isobutanol, sec-butanol, tert-butanol, benzyl alcohol, and propylene glycol methyl ether may be used. A mixture of xylene and n-butanol is preferred.

A preferred coating composition of the invention comprises a minimum amount of solvent since this reduces VOCs. The coating composition preferably comprises 2 –10 wt%solvent, and more preferably 2-5 wt%solvent, based on the total weight of the composition.

Additives

The coating composition of the invention optionally comprises a wide variety of additives. Examples of additives that are optionally present in the composition of the invention include glass flakes, flaky pigments, e.g. non-leafing aluminium, hydrocarbon resin, moisture scavenger, colour pigment, additional anticorrosive pigments, e.g. zinc phosphate, anti-settling agent, drying agents, and plasticisers.

Additional additives are preferably present in an amount of 0 to 10 wt%, more preferably 0.1-5 wt%, still more preferably 0.1 to 2.5 wt%and particularly preferably 0.2 to 2 wt%, based on the total weight of the coating composition.

Composition properties

A preferred coating composition of the present invention comprises:

(i) 5.0-10 wt%, more preferably 6.0-8.0 wt%, epoxy-based binder;

(ii) 1.5-7.5 wt%, more preferably 2.0-5.0 wt%, epoxy silane, wherein said epoxy silane comprises ethoxy groups and methoxy groups;

(iii) 70-85 wt%, more preferably 75-80 wt%, zinc dust;

(iv) 1.0-7.5 wt%, more preferably 2.0-4.0 wt%, curing agent; and

(v) 0.1-2.0 wt%, more preferably 0.1-1.5 wt%, aminoalkyl alkoxy silane, wherein said composition has a solids content of at least 75 %by volume, and a VOC content of 10 %wt or less, based on the total volume and weight of the composition respectively.

A further preferred coating composition of the present invention comprises:

(i) 5.0-10 wt%, more preferably 6.0-8.0 wt%, epoxy-based binder;

(iii) 70-85 wt%, more preferably 75-80 wt%, zinc dust;

(iv) 2.0-4.0 wt%, curing agent;

(v) 0.1-2.0 wt%, more preferably 0.1-1.5 wt%, aminoalkyl alkoxy silane; and

(vi) 3.0-6.0 wt%, filler, e.g. microspheres.

A yet further preferred coating composition of the present invention comprises:

(i) 6.0-8.0 wt%, epoxy-based binder;

(iii) 70-85 wt%, more preferably 75-80 wt%, zinc dust;

(iv) 2.0-4.0 wt%, curing agent;

(v) 0.1-2.0 wt%, more preferably 0.1-1.5 wt%, amino alkyl alkoxy silane;

(vi) 3.0-6.0 wt%, filler, e.g. microspheres; and

(vii) 0.2-3.0 wt%rheology modifier, based on the total volume and weight of the composition respectively.

A particularly preferred composition of the invention comprises less than 5 wt%, more preferably less than 4 wt%and still more preferably less than 3 wt%reactive diluent. An especially preferred coating composition is substantially free, e.g. free, of reactive diluent.

A preferred coating composition of the present invention has a solids content of at least 75 %by volume, preferably at least 80 %by volume, and more preferably at least 85 %by volume, based on the total volume of the composition.

A preferred coating composition of the present invention has a solids content of at least 90 wt%by weight, and more preferably at least 95 %by weight, based on the total weight of the composition.

A preferred coating composition of the present invention has a VOC content of 0-10 wt%, preferably 0-7.5 wt%, and more preferably 0-5 wt%, based on the total weight of the composition.

A preferred coating composition of the present invention has a VOC content of 175 g/L or less, and more preferably 150 g/L or less.

A preferred coating composition of the present invention has a pigment volume concentration (PVC) of 50-60 %, and more preferably 52-56%.

A preferred coating composition of the present invention has a Stormer viscosity of 70-140 KU, preferably 80-135 KU and still more preferably 90-130 KU.

A preferred coating composition of the present invention has a viscosity of 100-600 mPas, preferably 200-500 mPas and still more preferably 300-450 mPas.

A preferred coating composition of the present invention is sprayable, and preferably sprayable by airless spray. Preferably the composition is sprayable using an airless spray pump with a pump ratio at least 30: 1, preferably at least 40: 1. Preferably the composition is sprayable using an airless spray pump with an inlet air pressure of 0.2 to 0.8 MPa, and more preferably 0.3 to 0.5 MPa. Preferably the composition is sprayable under one or both of the afore-mentioned conditions with a hose length up to 50 meters. Suitable nozzle types are 519, 521, 523, 619, 621 and 623 from Graco. Corresponding nozzles are also available from other suppliers. The composition is preferably sprayable in a temperature range of -5 ℃ to 40 ℃, preferably 5 ℃ to 35 ℃.

Containers and kits

The present invention also relates to a container containing a coating composition as hereinbefore described.

Alternatively, the coating composition of the present invention may be provided in the form of a kit. A kit for preparing a composition as hereinbefore described, comprises:

(i) a first container containing epoxy-based binder, epoxy silane, wherein said epoxy silane comprises ethoxy groups and methoxy groups and zinc, preferably zinc dust; and

(ii) a second container containing curing agent and preferably aminoalkyl alkoxy silane.

The mixture present in the first container is herein referred to as component A. The mixture present in the second container is herein referred to as component B. Preferably the second container also contains a curing accelerator, i.e. component B comprises curing accelerator.

When present filler, e.g. microspheres may be present in component A or component B. Preferably, however, filler is present in component A.

When present rheology modifier may be present in component A or component B. Preferably, however, rheology modifier is present in component A.

When present levelling agent may be present in component A or component B. Preferably, however, levelling agent is present in component A.

When present defoaming agent may be present in component A or component B. Preferably, however, defoaming agent is present in component A.

When present dispersing agent may be present in component A or component B. Preferably, however, dispersing agent is present in component A.

When present other binder may be present in component A or component B. Preferably, however, other binder is present in component A.

When present solvent may be present in component A or component B.

When present additives may be present in component A or component B. Preferably, however, additives are present in component A.

When present reactive diluent is preferably present in component A.

Particularly preferably component B comprises, e.g. consists of, curing agent, and optionally aminoalkyl alkoxy silane and optionally curing accelerator. Preferably component B comprises, e.g. consists of, polyamine curing agent, and optionally aminoalkyl alkoxy silane and a curing accelerator. The component B preferably has an AHEW of 70 –200 g/eq, more preferably 80 –140 g/eq, and more preferably 90 –120 g/eq.

Preferably component B comprises 60-85 wt%, and more preferably 70-80 wt%of curing agent, based on the total weight of component B.

Preferably component B comprises 10-30 wt%, and more preferably 15-25 wt%aminoalkyl alkoxy silane, based on the total weight of component B.

Preferably component B comprises 1-10 wt%, and more preferably 1.5 to 5 wt%of curing accelerator, based on the total weight of component B.

Particularly preferably component A comprises of: epoxy-based binder; epoxy silane, wherein said epoxy silane comprises ethoxy groups and methoxy groups; zinc, preferably zinc dust; filler, e.g. microspheres; rheology modifier; levelling agent; defoaming agent; dispersing agent; other binder; solvent; and/or additives.

Preferably component A comprises 3-15 wt%, more preferably 5-10 wt%and still more preferably 6-8 wt%epoxy-based binder based on the total weight of component A.

Preferably component A comprises 1-10 wt%, more preferably 4.5-7.5 wt%and still more preferably 2.0-5.0 wt%epoxy-silane, wherein said epoxy silane comprises ethoxy groups and methoxy groups, based on the total weight of component A.

Preferably component A comprises 65-90 wt%, more preferably 70-85 wt%and still more preferably 75-82 wt%zinc, based on the total weight of component A.

Preferably component A comprises 2.0-10 wt%, more preferably 3.0-8.0 wt%and still more preferably 3.0-6.0 wt%filler, e.g. microspheres, based on the total weight of component A.

Preferably component A comprises 0-5.0 wt%, more preferably 0.2-3.0 wt%and still more preferably 0.3-2.0 wt%rheology modifier, based on the total weight of component A.

Preferably component A comprises 0-5 wt%, more preferably 0.1-2.5 wt%and still more preferably 0.2-1.0 wt%levelling agent, based on the total weight of the component A.

Preferably component A comprises 0 to 1.0 wt%, and more preferably 0.1 to 0.2 wt%defoaming agent, based on the total weight of the component A.

Preferably component A comprises 0 to 1.5 wt%, and more preferably 0.1 to 1 wt%, dispersing agent based on the total weight of the component A.

Preferably component A comprises 0-10 wt%co-binder, based on the total weight of the component A.

Preferably component A comprises 2–10 wt%, and more preferably 2-5 wt%solvent, based on the total weight of the component A.

Preferably component A comprises 0-5 wt%, more preferably 0.1-4 wt%and still more preferably 0.5-3 wt%reactive diluent, based on the total weight of component A. Manufacture

The present invention also relates to a method for preparing a composition as hereinbefore described, comprising mixing:

(i) epoxy-based binder;

(iii) zinc, preferably zinc dust;

(iv) curing agent; and

(v) preferably aminoalkyl alkoxy silane.

In a preferred method of the invention, the epoxy-based binder, epoxy silane and zinc are pre-mixed (i.e. as component A) and separately the curing agent and, if present, accelerator and aminoalkyl alkoxy silane are mixed (i.e. as component B) . Preferably filler, e.g. microspheres are added to the epoxy-based binder, epoxy silane and zinc mixture. Preferably other ingredients recited herein as present in component A in the kit is added to the epoxy-based binder, epoxy silane and zinc mixture. Preferably the two resulting mixtures are combined (e.g. immediately prior to use) and mixed. Any conventional mixing equipment may be used.

Application to surfaces

The present invention also relates to a method of providing a coating on a surface, wherein said method comprises:

(i) applying a composition as hereinbefore described; and

(ii) drying and/or curing said composition to form a coating on the surface.

Optionally the surface is pre-treated prior to application of the coating composition of the invention. Preferably, the coating composition is applied directly to the surface. This means the coating composition, comprising zinc, is directly in contact with the surface.

The coating composition of the present invention may be part of a coating system. In a preferred coating system, the coating composition of the invention is applied directly to the surface and then another coating, e.g. an epoxy coating, is applied thereto. Preferably the coating of the present invention is a primer.

The coating composition of the invention may be applied to a substrate by any conventional coating method, e.g. spraying, rolling, dipping etc. Preferably the coating composition is applied by spraying, and more preferably by airless spraying. Spraying is preferred as it enables large surface areas to be coated in a uniform manner. Additionally spraying can be used to coat non-horizontal surfaces.

Preferably the coating is applied using an airless spray pump with a pump ratio of at least 30: 1, and preferably at least 40: 1. Preferably the coating is applied using an airless spray pump with an inlet air pressure of 0.2 to 0.8 MPa, and more preferably 0.3 to 0.5 MPa. Preferably the coating is applied using one or both of the afore-mentioned conditions with a hose length up to 50 meters. Suitable nozzle types are 519, 521, 523, 619, 621 and 623 from Graco. Ccorresponding types are also available from other suppliers. Application of the coating composition is preferably carried out in a temperature range of -5 ℃ to 40 ℃, preferably 5 ℃ to 35 ℃.

Preferably the substrate is metal, in particular steel.

Preferred coatings have a wet film thickness of 40-90 μm, and more preferably 50 to 85 μm. The relatively low viscosity of the coating composition of the present invention makes it feasible to prepare relatively thin wet films.

The present invention also relates to a coating comprising a coating composition as hereinbefore described. Optionally the coating is applied in a number of steps, wherein a first layer of the coating is applied, dried and cured, then a subsequent layer of coating is applied.

The coating composition of the present invention may be used to form a single layer coating or a multilayer coating (i.e. a coating system) . In the case of a multilayer coating the coating composition of the present invention is preferably used to form a first layer on the substrate, e.g. metal surface. Preferably a second coat is applied.

Curing

Preferably the coating of the present invention is cured. Thus, once a substrate (e.g. a metal substrate) is coated with the coating composition of the invention, the coating is preferably cured. Preferably the coating of the present invention cures in ambient conditions, e.g. in the temperature range -5-50 ℃. Preferably therefore the coating of the present invention does not require heat to cause curing. Preferably the curing time at ambient temperature (20-40 ℃) (i.e. time to achieve surface dryness by the thumb-test) is 0.5-20 hr, more preferably 2-10 hr and still more preferably 2-8 hr.

Coatings and Articles

The present invention also relates to a substrate coated with a coating composition as hereinbefore described or a coating as hereinbefore described. The coating composition of the invention may be applied to any substrate. Representative examples of substrates include metal substrate and, in particular, steel, galvanized steel, stainless steel, aluminium, and copper. Particularly preferably the substrate is steel.

The coatings of the present invention provide anti-corrosion coatings on such substrates. The types of metal substrates that are preferably coated with coatings of the present invention are therefore those which are in contact with corrosive environments. Examples of metal substrates include bridges, oil rigs, steel infrastructure, pipes, valves, tanks, containers, ship parts, etc. A particularly preferred substrate is a bridge, oil rig or steel infrastructure.

The substrate may be partially, or completely coated, with the coating composition or coating of the invention. Preferably, however, all of the substrate (e.g. all of the external walls) is coated with the coating composition or coating of the invention.

Preferably the coating comprises at least 80 wt%, preferably at least 85 wt%zinc dust, based on the total weight of the dried coating.

Preferred coatings have a dry thickness of 40-90 μm, and more preferably 50 to 85 μm.

Coating system

The present invention preferably provides a composition which is a zinc primer. Zinc primers are used for galvanic corrosion protection of steel structures such as bridges, infrastructure, buildings, platforms and power plants. The zinc primer works as the sacrificial anode in the galvanic system and thus relies on direct contact with the steel. Thus, preferably the zinc primer is the first layer in a coating system.

A coating system for galvanic corrosion protection preferably comprises, e.g. consists of, three layers: a zinc primer layer, a mid-coat layer and a top-coat layer. The mid-coat layer is preferably epoxy based. The top-coat layer is preferably polyurethane or polysiloxane based. Together, the coatings in the system provide both galvanic protection and barrier protection to the steel substrate.

Uses

The present invention also provides the use of a composition as hereinbefore described to form a coating, preferably an anti-corrosive coating, on at least one surface of an article. Preferably the surface is a metal surface as hereinbefore described.

The invention will now be described with reference to the following non-limiting examples.

EXAMPLES

Materials

The compounds used in the examples were all available commercially. They are summarised in the table below.

Table 1: Compounds used in examples.

*combined as “Additives” in Tables 2-4.

Preparation of compositions

Example compositions were prepared by a conventional technique for paint production.

The compositions were prepared as a two-component mixture, component A and component B. Component A was prepared by mixing binder, epoxy silane and solvent in a can, with stirring at low speed for 5 minutes. Additives, dispersing agent and rheology modifiers were then added and mixed, at a high stirring speed, for another 5 minutes. Zinc dust was added, and the compositions mixed at high speed for 10 minutes. Finally, microspheres and further solvent was added, and stirred at medium speed for 5 minutes.

In a separate can, component B was prepared by mixing curing agent, aminoalkyl alkoxy silane , and accelerator and shaking for 3 minutes.

The two components, A and B, were then mixed at the point of use.

The compositions prepared are summarised in the Tables below. All wt%specified herein are based on the total mixed composition, unless otherwise specified.

Comparative compositions (herein CE) were prepared in an analogous manner.

Preparation of samples for testing and test methods

· Calculating PVC and vol%solids

According to ISO 4618-1: 2018 the PVC refers to the ratio of the volume of pigment and other solids particles in a product to the total volume of the non-volatile matter.

In order to be able to calculate the Pigment Volume Concentration (PVC) of a coating from a formulation expressed in proportions by weight, the non-volatile content and density of every component of the coating material is required. From these parameters the approximate volume of the individual components in the coating film can be calculated.

The following equation was used for the calculation of PVC (European Coatings Handbook, Brock, Groteklaes and Mischke, Vincentz Verlag 2010) :

The following equations were used to calculate vol%solids:

Volume = (weight /density)

· Calculation of Volatile Organic Compounds (VOC)

The Volatile Organic Compounds, VOC (g/L) of the coating compositions was calculated as follows:

· Viscosity, KU

The consistency of the coating compositions was determined according to ASTM D562-10: 2018 Method B using a digital Stormer-type viscometer. The measurement was done on samples in a 500 mL container at 23℃.

· Viscosity, cone and plate method

Viscosity was determined according to ISO 2884-1: 2006 at 23 ℃ and at a shear rate of 10000 s^-1.

· Storage stability

The sample was stored for 4 weeks at 50℃ in a closed container. Viscosities (KU and cone and plate) , were measured before and after storage. The storage stability test is failed if the cone and plate viscosity has doubled, and if the KU viscosity is above 140 KU after the storage test period.

· Airless spray

The composition was applied by airless spray using an airless spray pump (Graco Merkur G48, pump ratio 48: 1, inlet air pressure 0.3-0.5 MPa, nozzle Graco 519, 521, 523, 619, 621 and 623) . The spray pattern of the composition was visually observed. Observation of “fingers” or “tails” in the spray pattern is considered a failure, because such defects will cause an uneven film build. Dry spraying is also considered a failure, as it will cause less or no flow and levelling in the applied paint.

The appearance of the wet and dry film was checked. If the spray pattern is free of fingers or tails, and no dry spray has occurred, an even level film with no orange peel is obtained and the composition is considered to have passed the test.

If the composition must be thinned above 5%to pass the above criteria, the airless spray test is failed.

· Drying time

The drying times were assessed by manual thumb by applying the coating compositions to glass panels using an applicator with 200 μm gap. The coated glass panels were immediately placed in climate chambers at 5 ℃, 85%RH and 23 ℃, 60%RH respectively. The drying state of the coating films were assessed every 1-2 h according to ASTM D1640-03 “Standard Test Methods for Drying, Curing, or Film Formation of Organic Coatings at Room Temperature” .

· Preparation of samples for accelerated corrosion testing

Accelerated corrosion tests were conducted by applying the coating composition by airless spray at a temperature of 23 ℃, and a relative humidity of 60-80%, to steel substrates with a cleanliness corresponding to Sa 21/2. The zinc rich coating compositions were applied to a wet film thickness resulting in a dry film thickness of 60 –100 μm. Before exposure to the test conditions, the applied coatings were dried and cured at room temperature (23 ℃, 60-80 %RH) for 14 days.

· Salt spray testing was conducted in neutral salt fog at 35 ± 2 ℃ according to ISO 9227: 2012 “Corrosion tests in artificial atmospheres –Salt spray tests” .

· Continuous condensation testing was conducted at 38 ± 2 ℃ according to ISO 6270-1: 1998 "Paint and varnishes –Determination of resistance to humidity, Part 1:Continuous condensation"

Results

Table 2: Sprayability and storage stability results

The results in Table 1 show that that compositions comprising ethoxy-functionalised epoxy silane have greater stability than compositions comprising methoxy-functionalised epoxy silane. The comparative composition comprising 0.3 wt%alkoxy-functionalised epoxy silane in component A (CE4) performed significantly less well. The prior art composition could not be sprayed at all due to its high viscosity.

The results in Table 2 show that the nature of the alkoxy-functional group in the epoxy silane has an important effect on drying and curing time. The compositions comprising methoxy-functionalised epoxy silane have a faster drying and curing time than the composition comprising ethoxy-functionalised epoxy silanes. It was also found that curing speed may also be improved by the presence of aminoalkylmethoxysilane in component B (see the results for example 1 versus example 2) .

Compositions comprising a mixture of methoxy and ethoxy-functionalised epoxy silane in component A, and aminoalkyl alkoxy silane in component B, provided the optimum balance of sprayability, storage stability as well as drying and curing time.

The results in Table 3 show that the anticorrosive performance of the coatings formed from the compositions of the invention is strong. Specifically, the coatings pass all of the different anti-corrosive tests applied to them.

The compositions of the invention therefore have a high volume solid content, and low VOC content, but are sprayable (without any thinning) , and have acceptable viscosity. The compositions are also stable to storage, and dry and cure quickly. The resulting coatings have strong anti-corrosive performance.

Table 3: Drying and Curing time

Table 4: Anticorrosive testing

Claims

A coating composition, preferably a primer, comprising:

(i) epoxy-based binder;

(ii) epoxy silane, wherein said epoxy silane comprises ethoxy groups and methoxy groups;

(iii) zinc, preferably zinc dust;

(iv) curing agent; and

(v) preferably aminoalkyl alkoxy silane,

wherein said composition has a solids content of at least 75 %by volume, and a VOC content of 10 %wt or less, based on the total volume and weight of the composition respectively.
A composition as claimed in claim 1, comprising a mixture of epoxy silanes.
A composition as claimed in claim 1 or 2, wherein said epoxy silane is a 3-glycidoxyalkylalkoxysilane, preferably a 3-glycidoxypropylalkoxysilane.
A composition as claimed in any preceding claim, wherein said epoxy silane comprises 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane.
A composition as claimed in any preceding claim, wherein the total amount of zinc present in the coating composition is preferably 65-90 wt%, more preferably 70-85 wt%and still more preferably 75-80 wt%, based on the total weight of the composition.
A composition as claimed in any preceding claim, wherein said curing agent comprises at least one benzylamine motif:
A composition as claimed in any of the preceding claims, comprising an aminoalkyl alkoxy silane , preferably an aminopropyl alkoxy silane.
A composition as claimed in any preceding claim which does not comprise a reactive diluent.
A composition as claimed in any preceding claim, having at least one of, preferably at least two of, more preferably at least three of and still more preferably all of:

- a solids content of at least 80 %by volume, based on the total volume of the composition;

- a solids content of at least 90 wt%by weight, and more preferably at least 95 %by weight, based on the total weigh of the composition;

- a VOC content of 0-10 wt%, preferably 0-7.5 wt%, and more preferably 0-5 wt%, based on the total weight of the composition;

- a VOC content of 175 g/L or less, and more preferably 150 g/L or less.

- a pigment volume concentration (PVC) of 50-60 %, and more preferably 52-56%.

- a Stormer viscosity of 70-140 KU, preferably 80-135 KU and still more preferably 90-130 KU; and/or

- a viscosity of 100-600 mPas, preferably 200-500 mPas and still more preferably 300-450 mPas.
A method for preparing a composition as claimed in any preceding claim, comprising mixing:

(i) epoxy-based binder;

(ii) epoxy silane, wherein said epoxy silane comprises ethoxy groups and methoxy groups;

(iii) zinc, preferably zinc dust;

(iv) curing agent; and

(v) preferably aminoalkyl alkoxy silane.
A kit for preparing a composition as claimed in any one of claims 1 to 9, comprising:

(i) a first container containing epoxy-based binder, epoxy-silane, wherein said epoxy silane comprises ethoxy groups and methoxy groups and zinc, preferably zinc dust; and

(ii) a second container containing curing agent and preferably aminoalkyl alkoxy silane.
A container containing a composition as claimed in any one of claims 1 to 9.
A method of providing a coating on a surface, wherein said method comprises:

(i) applying a composition as claimed in any one of claims 1-9; and

(ii) drying and/or curing said composition to form a coating on the surface.
A coating on a surface, wherein said coating comprises, or derives from, a composition as claimed in any one of claims 1-9.
Use of a composition as claimed in any one of claims 1-9 to form a coating on a least one surface of an article.