coating

Abstract

A primer coating composition comprising: (i) an epoxy resin; (ii) 2.0 to 15 weight percent of a silane; (iii) a hardener; (iv) a glycol ether solvent; and (v) 1.0 to 9.0 weight percent of microspheres.

Description

[Technical field]

[0001] The present invention relates to a primer coating composition that can be applied to moist, damp, wet, or rusted substrates to provide an anti-corrosive primer layer on the substrate. The present invention requires a combination of an epoxy resin, a silane, microspheres, and a glycol ether solvent. [Background technology]

[0002] [Background of the invention] Before applying a primer, the surface must often be properly prepared to obtain the appropriate roughness and cleanliness. This is usually achieved by cleaning and sandblasting. If the roughness and cleanliness are insufficient, the anticorrosive primer cannot be expected to provide long-term substrate protection.

[0003] Poorly prepared surfaces require a coating that offers more surface resistance than typical epoxy primers. Mastic-type epoxy primers have been shown to be suitable for poorly prepared surfaces. However, one problem that has yet to be solved is application to damp or wet substrates or to rusted substrates, especially flash rusted surfaces.

[0004] The importance of solving this problem has increased in recent years with the advent of ultra-high pressure water jet (UHPWJ) surface preparation instead of traditional sandblasting. When the substrate is water jetted, the surface topography of the steel is not roughened and old paint residues may remain on the substrate. Residual water also remains on the surface, so it is preferable to coat the surface before it dries, not only for time saving purposes but also to minimize the amount of flash rust that forms. In hot climates, drying can occur quickly, which can result in flash rust on the surface. It would be beneficial to provide a coating composition that adheres to damp or wet substrates, flash rusted substrates and substrates with old paint residues.

[0005] Applying anti-rust primers to UHPWJ substrates is difficult because moisture remains on the substrate and causes flash rust on wet steel. Therefore, a coating composition that is suitable for application on damp or wet substrates and can tolerate old paint residue would be beneficial. Also, a coating composition that has a high volume to solids ratio (low volatile organic compound (VOC) content), low density, low viscosity for good application properties, and long pot life in addition to excellent anti-rust properties would be advantageous.

[0006] For wet and moist surface resistance, ketimine or aldimine based hardeners are commonly used. Ketimines or aldimines are hydrolyzed in the presence of water to provide free amines and ketones or aldehydes. The free amines react with epoxy functional resins and the ketones or aldehydes preferably evaporate from the coating film. This makes ketimines and aldimines suitable for use on wet and moist substrates. The drawback of using ketimines or aldimines is the release of ketones and aldehydes, which are VOCs and have adverse health and safety effects.

[0007] In addition, the thick wet film thickness can hinder the release of ketones and aldehydes, leading to the entrapment of volatile components. Additionally, there are challenges associated with the manufacture and storage of ketimines and aldimines, as they are hydrolytically unstable. Also, some moisture is required as ketimines and aldimines must hydrolyze to form free amines. Thus, if a ketimine or aldimine cure is applied too dry, it will cure very slowly.

[0008] JP 2021-143270 A describes an anti-corrosive coating for marine structures that can be applied to wet substrates. The coating composition includes a specific polyamine curing agent to provide a coating composition that can be applied to wet surfaces.

[0009] JP 6-629540 A describes an anti-rust coating composition that can be applied to wet surfaces. Polyoxyalkylene polyamines, Mannich modified amines or ketimine hardeners are used to provide a coating that can be applied to wet surfaces.

[0010] JP 6-629539 A describes a coating composition that can be applied over deteriorated paint without any pretreatment other than rinsing with water, and this is achieved by using polyoxyalkylene polyamines, Mannich modified amines, or ketimine curing agents.

[0011] WO2020 / 253732 describes a coating composition that can insulate steel from LNG spills. It achieves this by using low density fillers and Jeffamine hardeners.

[0012] WO2012 / 035520 describes impact-resistant multilayer coatings based on epoxy resins, microspheres and amine or isocyanate hardeners. The importance of silanes and glycol ethers is not emphasized.

[0013] US2020 / 017711 describes a curable composition for footwear comprising a binder and a polysiloxane resin. The use of a polyurethane binder is preferred.

[0014] CN106024946 describes a solar cell backing layer: the pattern layer comprises a first host resin, the intermediate layer comprises a second host resin, and the weather-resistant layer comprises a fluororesin.

[0015] US2007 / 048445 describes a sound deadening coating for vehicles, in which an epoxy resin is used in the examples. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] Patent No. 2021-143270 [Patent Document 2] Japanese Patent Publication No. 6-629540 [Patent Document 3] Japanese Patent Publication No. 6-629539 [Patent Document 4] International Publication No. 2020 / 253732 [Patent Document 5] International Publication No. 2012 / 035520 [Patent Document 6] US Patent Application Publication No. 2020 / 017711 [Patent Document 7] Chinese Patent 106024946 [Patent Document 8] US Patent Application Publication No. 2007 / 048445 Summary of the Invention [Problem to be solved by the invention]

[0017] WO2020 / 065588 describes a composition comprising an amino-functional silane and a photoluminescent compound. [Means for solving the problem]

[0018] The present inventors have now devised a primer coating composition that is resistant to flash rust and wet or damp substrates, i.e., the primer layer composition of the present invention can be applied to wet or rusted substrates and adheres thereto. The coating composition of the present invention also has good application properties, long pot life and good rust prevention properties. Without wishing to be bound by theory, it is speculated that these effects are related to the specific solvents used in the coating composition, along with the prescribed levels of silane and microspheres. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] [Summary of the Invention] Thus, in one aspect, the present invention provides a primer coating composition comprising: (i) epoxy resin; (ii) 2.0 to 15 wt. % silane; (iii) a hardener; (iv) glycol ether solvents; and (v) 1.0-9.0 wt.% microspheres.

[0020] In any embodiment of the present invention, the glycol ether solvent is preferably represented by formula (I):

[0021] [ka]

[0022] In the formula, x is 1 to 3; R is C1~C 16 is an aliphatic group; and R' is C1 to C 16 It is an aliphatic group.

[0023] In one aspect, the present invention comprises: (i) epoxy resin; (ii) 2.0 to 15 wt. % silane; (iii) a hardener; (iv) glycol ether solvents; (v) 1.0 to 9.0 weight percent microspheres; and (vi) Hydrocarbon resins A primer coating composition comprising:

[0024] In one aspect, the present invention comprises: (i) epoxy resin; (ii) 2.0 to 15 wt. % silane; (iii) a hardener; (iv) glycol ether solvents; (v) 1.0 to 9.0 weight percent microspheres; and (vi) Reactive diluents A primer coating composition comprising:

[0025] In one aspect, the present invention comprises: (i) epoxy resin; (ii) 2.0 to 15 wt. % silane; (iii) a hardener; (iv) glycol ether solvents; (v) 1.0-9.0 wt.% microspheres; (vi) hydrocarbon resins; and (vii) Reactive diluents A primer coating composition comprising:

[0026] From another aspect, the present invention comprises: A component (A) comprising an epoxy resin; and A kit comprising: component (B) comprising a curing agent; At least one of components (A) or (B) comprises a silane, a glycol ether solvent, and microspheres; when components (A) and (B) are combined, the resulting primer layer composition comprises 2.0 to 15 weight percent silane and 1.0 to 9.0 weight percent microspheres. Kits suitable for preparing the primer coating compositions of the present invention are provided.

[0027] Viewed from another aspect, the present invention provides a metal substrate coated with a primer coating composition as defined herein.

[0028] Viewed from another aspect, the present invention provides a metal substrate having a cured primer coating composition as defined herein.

[0029] Viewed from another aspect, the present invention provides a method for preparing a primer coating composition as defined herein, said method comprising the steps of blending components (A) and (B), Component (A) comprises an epoxy resin; Component (B) comprises a curing agent; At least one of components (A) or (B) comprises a silane; a glycol ether solvent and microspheres, such that when components (A) and (B) are combined, the resulting primer layer composition comprises 2.0 to 15 wt. % silane and 1.0 to 9.0 wt. % microspheres.

[0030] In another aspect, the present invention provides a method for applying a primer coating composition to a substrate, the method comprising the steps of blending components (A) and (B), Component (A) comprises an epoxy resin; Component (B) comprises a curing agent; blending, where at least one of components (A) or (B) comprises a silane; a glycol ether solvent; and microspheres, such that when components (A) and (B) are combined, the resulting primer layer composition comprises 2.0-15 wt.% silane and 1.0-9.0 wt.% microspheres to form a primer layer composition; applying the composition to a substrate, which is ideally wet and / or rusty, for example by airless spraying, and optionally curing the coating.

[0031] Viewed from another aspect, the present invention provides a method of coating a wet metal substrate, the method comprising: 1) blending component A with component B; Component (A) comprises an epoxy resin; blending, component (B) comprising a curing agent; and at least one of components (A) or (B) comprising a silane; a glycol ether solvent; and microspheres, such that when components (A) and (B) are combined, the resulting composition comprises 2.0 to 15 weight percent silane and 1.0 to 9.0 weight percent microspheres; 2) applying the composition to a wet substrate; 3) forming the composition into a film and curing it.

[0032] Viewed from another aspect, the present invention provides a kit suitable for the preparation of a primer coating composition as defined herein, said kit comprising: (i) epoxy resin; (ii) silane; (iii) glycol ether solvents; and (iv) component (A) comprising microspheres; and component (B) which comprises at least one curing agent.

[0033] Viewed from another aspect, the present invention provides the use of a primer coating composition as defined herein for application to a wet and / or rusty substrate.

[0034] In all embodiments, it is preferred that the epoxy resin is a liquid. In all embodiments, the solvent preferably comprises propylene glycol n-butyl ether. In all embodiments, the silane is preferably an epoxy silane.

[0035] [Definition] The present invention relates to a primer coating composition. The term coating composition is used to define a composition formed from the combination of a first composition (component A) and a second composition (component B). To prevent premature curing, the primer coating composition of the present invention is provided in two parts: a first composition (component A) containing an epoxy resin, and a second composition (component B) containing a curing agent. Other components of the composition are preferably present in component (A), but may be added via component (B). The weight percentages herein are based on the entire primer layer composition. The weight percentages of the components in components (A) and (B) can be easily determined based on the weight percentages in the final primer layer composition and the mixing ratio of components (A) and (B).

[0036] [Detailed Description of the Invention] The present invention relates to a primer coating composition for substrates such as metal substrates, particularly steel substrates. The primer coating composition can be applied to damp, wet or rusted substrates. The substrate may form part of any article to which a primer coating needs to be applied, for example a large metal structure.

[0037] The primer coating composition forms an epoxy primer layer on the substrate. The primer layer can be optionally overcoated with a topcoat, tie coat, antifouling coating, or smoke-resistant coating. Thus, the primer coating of the present invention can be the only layer applied to the substrate, or it can be a layer in a coating system that includes the primer coating and additional layers. No additional topcoat or overcoat layers are required. However, it is understood that if the substrate is the exterior of a marine vessel hull, the primer is typically coated with an antifouling paint, optionally with a tie coat between the primer layer and the antifouling layer. Additionally, if the substrate is exposed to outdoor conditions (e.g., ultraviolet radiation from the sun), it is beneficial to coat the primer with a UV- and weather-resistant topcoat. The primer coating provides good rust protection.

[0038] In one embodiment, the primer coating composition may be applied as a single layer or as two or more layers. Two coats of the primer coating composition may be applied to the substrate. It is also possible that two different primer coating compositions are applied.

[0039] The primer coating composition may be overcoated with a topcoat. The primer coating composition may also be overcoated with a tie coat and an antifouling coating layer. The primer coating composition in these embodiments may be applied by itself as a single coat or as two coats.

[0040] A suitable system includes two primer coats plus a top coat. A suitable system includes two primer coats + tie coat + antifouling. A suitable system includes one primer coat plus a top coat.

[0041] If the substrate is not on the outside of a boat hull or is not exposed to outdoor conditions (ultraviolet rays from sunlight), an overcoat may not be necessary. However, to ensure weatherability and UV resistance of the coating system, the primer coating composition is preferably overcoated with a topcoat. If an overcoat layer is present, any known overcoat layer may be used. It is noted that it is preferred to apply the coating composition in two applications, i.e., in two application steps. However, the composition may be applied alone in one coat.

[0042] [Primer coating composition] A special feature of the primer coating composition of the present invention is its high solids content, which results in a low content of volatile organic compounds (VOCs) present. The primer layer coating composition preferably has a solids content of at least 70% by weight, such as at least 75% by weight, more preferably at least 80% by weight. The volume solids content (expressed as %) is often referred to as "VS%". VS% is determined according to ASTM D5201-05a(2020). The primer coating composition has a volume solids% of at least 70%, such as at least 75%, preferably at least 80%.

[0043] A high solid content results in a low VOC content. The VOC content is preferably 220 g / L or less, more preferably 200 g / L or less, even more preferably 180 g / L or less, for example 160 g / L or less. The VOC can be theoretically determined (ASTM D5201-05a(2020)).

[0044] The pot life of the primer coating composition of the present invention is preferably at least 30 minutes, more preferably at least 60 minutes, e.g. 90-120 minutes at 23°C. By pot life is meant the time during which, after mixing of the first and second components (A) and (B), the composition is still applicable to a substrate by an airless spray procedure. If the composition cures too quickly, the pot life of the coating composition will be very short. A pot life of less than 30 minutes is commercially unfeasible, taking into account the time it takes to coat large objects such as ship blocks and the length of hoses up to 150 m feeding the spray gun.

[0045] Many of the important properties of the compositions of the present invention are a result of the relatively low viscosity, yet high solids content, of the claimed compositions.

[0046] The viscosity of the primer coating composition, measured immediately after combination of the two components, may be from 200 to 1100 mPas at 23° C., for example from 200 to 1000 mPas, especially from 450 to 800 mPas.

[0047] It will be understood that the composition will harden over time, and thus the viscosity of the composition will increase during hardening. The viscosities quoted are initial viscosities measured immediately after mixing, and thus before the hardening process has taken place to any significant extent. Immediately after mixing means within 10 minutes of mixing.

[0048] Ideally the viscosity of the primer coating composition measured after 60 minutes is less than 2200 mPas, more ideally less than 2000 mPas.

[0049] The pigment volume concentration of the primer coating composition of the present invention is preferably 30 to 45%, for example 32 to 42%.

[0050] [Epoxy resin] The primer coating composition comprises at least one binder based on an epoxy resin. A mixture of epoxy resins can also be used. When multiple epoxy resins are used, it is the combination of these epoxy resins that forms the binder in the primer layer composition.

[0051] Just before applying the primer layer composition to a substrate, a first composition (component A) containing an epoxy resin is mixed with a second composition (component B) containing a curing agent to form a primer layer composition, which is then applied to a substrate and cured to form a primer layer on the substrate.

[0052] The binder in the primer layer composition may comprise one or more epoxy resins. Ideally, the primer layer composition comprises at least one liquid epoxy resin. The term liquid refers to the state of the epoxy resin at room temperature and pressure of 23° C. and 1 atmosphere.

[0053] The terms epoxy resin or epoxy binder are used interchangeably herein. Preferably, the epoxy resin is an aromatic or aliphatic epoxy binder, and preferably contains one or more epoxy groups per molecule. The epoxy groups may be in the internal or terminal positions of the epoxy binder, or on cyclic structures incorporated in the epoxy binder. Preferably, the epoxy-based binder contains at least two epoxy groups so that a crosslinked network can be formed.

[0054] It should be understood that the epoxy binders of the present invention also include binders having a conventional epoxy backbone, but in which the epoxy end groups are modified with acrylic or methacrylic functional groups that are curable with the same curing agents as the epoxy groups.

[0055] Suitable aliphatic epoxy-based binders include epoxy and modified epoxy binders selected from cycloaliphatic diglycidyl ethers, such as diglycidyl ether-based hydrogenated bisphenol A, hydrogenated bisphenol F, and dicyclopentadiene-based binders, glycidyl ethers, such as polyglycidyl ethers of polyhydric alcohols, epoxy-functional acrylic resins, or combinations thereof.

[0056] Suitable aromatic epoxy-based binders include epoxy and modified epoxy binders selected from bisphenol-type epoxy-based binders such as diglycidyl ethers of bisphenol A, bisphenol F and bisphenol S, resorcinol diglycidyl ether (RDGE), novolac-type epoxy-based binders such as epoxy phenol novolac resins, epoxy cresol novolac resins and bisphenol A epoxy novolac resins, glycidyl ethers of dihydroxynaphthalene or any combination thereof.

[0057] In a preferred embodiment, the epoxy-based binder is an aromatic epoxy-based binder, preferably derived from a combination of an aromatic coagent containing at least two hydroxyl groups and a compound containing at least one epoxide functional group.

[0058] The preferred epoxy binder is a bisphenol epoxy binder. The preferred epoxy binder is a bisphenol A epoxy binder and a bisphenol F epoxy binder or a bisphenol A / F epoxy binder. In a preferred embodiment, the epoxy binder is a bisphenol A epoxy resin, and most preferably, the epoxy binder is an unmodified liquid bisphenol A epoxy resin.

[0059] The epoxy-based binder may be a modified epoxy-based binder, preferably modified with a fatty acid, polypropylene oxide and / or polyethylene oxide, acrylic acid, carboxylic acid or carboxy-terminated butadiene acrylonitrile (CTBN).

[0060] The solids content in said epoxy based binder is preferably greater than 70% by weight, preferably greater than 80% by weight, preferably greater than 90% by weight, most preferably greater than 99% by weight. In a further preferred embodiment, said epoxy based binder is solvent free.

[0061] Examples of suitable epoxy-based binders that are commercially available include: - Bisphenol A type epoxy binder: DER331 and DER332 manufactured by Olin Epoxy Co., Ltd. - Bisphenol F epoxy binder: Epikote 862 from Hexion, DER354 from Olin Epoxy - Mixture of Bisphenol A and Bisphenol F epoxy binders: DER352 from Olin Epoxy, Epicoat 235 from Hexion It is.

[0062] The epoxy-based binder may be a liquid epoxy-based binder, a semi-solid epoxy-based binder, or a solid epoxy-based binder, or a combination thereof. It should be understood that "liquid" and "solid" refer to the physical state of the epoxy-based binder at ambient temperature and pressure (23°C and 1 atm). In a preferred embodiment, the epoxy-based binder is a liquid epoxy-based binder. In a preferred embodiment, the epoxy-based binder is a liquid bisphenol A type epoxy resin.

[0063] The epoxy-based binder may have an epoxy equivalent weight (EEW) value of 140 to 1000. It is particularly preferred if the EEW is less than 500, for example 150 to 270, in particular 160 to 200.

[0064] The number of "epoxy equivalents" is the sum of the contributions from each of the one or more epoxy resins and the contributions from other epoxy-containing components such as the silane and reactive diluents. The contribution from each of the one or more epoxy resins to the epoxy equivalent weight is defined as grams of epoxy resin divided by the epoxy equivalent weight of the epoxy resin, where the epoxy equivalent weight of the epoxy resin is determined as grams of epoxy resin equivalent to 1 mole of epoxy groups. In the case of adducts with epoxy resins, the contributions of the reactants prior to the adduct are used to determine the number of "epoxy equivalents" in an epoxy-based binder system.

[0065] The viscosity of the liquid epoxy binder is preferably 1000 to 20000 mPas, more preferably 2000 to 15000 mPas. It is most preferable to use a liquid bisphenol A type epoxy binder.

[0066] When liquid, semi-solid and solid epoxy binders are present in the epoxy binder system, it is preferred that the liquid epoxy binder is in excess of the semi-solid and / or solid epoxy binder.

[0067] The epoxy resin is preferably present in an amount of 5.0-40% by weight of the primer coating composition, such as 10-40% by weight of the primer coating. More preferably, the epoxy resin is present in an amount of 20-40% by weight, especially 20-30% by weight. When a blend of epoxy resins is used, these percentages refer to the total epoxy resin content, i.e. the respective weight percentages are added.

[0068] In a preferred embodiment, the epoxy binder comprises a bisphenol A based binder, such as 4,4'-isopropylidenediphenol-epichlorohydrin resin, a bisphenol F based binder and / or a novolac based binder. In a preferred embodiment, the epoxy binder system comprises one or more bisphenol A epoxy based binders. Bisphenol A epoxy based binders are known to those skilled in the art and have the general formula:

[0069] [ka]

[0070] In one embodiment, the epoxy-based binder system comprises one or more bisphenol F epoxy-based binders.

[0071] The EEW value of the bisphenol F epoxy binder may be from 100 to 350. However, the EEW is preferably 300 or less, for example from 100 to 300, especially from 150 to 200. Preferably, the bisphenol F epoxy binder is a liquid.

[0072] The Mw of the bisphenol F resin may be greater than 300 g / mol. A preferred bisphenol F (4',4'-methylene bisphenol) epoxy-based binder is obtained from a combination of bisphenol F and epichlorohydrin. The use of a difunctional epoxy-based bisphenol F binder is particularly preferred.

[0073] Two or more bisphenol F binders may be used in combination. The viscosity of the bisphenol F binder is preferably 1000 to 10000 mPas, more preferably 2000 to 5000 mPas.

[0074] [Silane] The coating composition of the present invention also contains at least one silane, which can improve drying characteristics at low temperatures, flexibility, adhesion to substrates, and anti-corrosion performance.

[0075] The silane may be provided as part of component A and / or as part of component B, preferably as component A. Ideally, the silane contains an epoxy group. The silanes used in the present invention are generally of low Mw, such as less than 400 g / mol. Suitable silanes are represented by the general formula (III) or (IV):

[0076] [ka]

[0077] In the formula, z is an integer of 1 to 3. y is an integer from 1 to 2; R 2 is a hydrocarbylene group having 1 to 12 C atoms, optionally containing an ether or amino linker, R 1 is a hydrocarbyl group having 1 to 12 C atoms; Y is a functional group attached to R that can react with a corresponding hardener or binder functional group, preferably an amine or epoxy group; Each X independently represents a halogen group or an alkoxy group.

[0078] Preferred functional groups Y are isocyanate, epoxy, glycidyl ether, amino, hydroxy, thiol, carboxy, acrylate or methacrylate groups. Said Y group may be attached to any part of the chain R. When Y represents an epoxy group, it will be understood that R has at least two carbon atoms to form an epoxide ring system.

[0079] Particularly preferably, Y is an amino group or an epoxy group. The amino group is preferably NH2. The epoxy group is preferably Y.

[0080] When the Y group is an epoxy, it is preferred that the silane is provided separately from the amine-based hardener composition, e.g., with the epoxy binder. Generally, in the kits of the invention, the silane should not react with any of the components of the kit in which the silane is present.

[0081] X is particularly preferably an alkoxy group, such as a C1-6 alkoxy group, especially a methoxy or ethoxy group. It is also particularly preferred when two or three alkoxy groups are present. Thus, z is ideally 2 or 3, especially 3. The subscript y is preferably 2.

[0082] R 1 is C 1-4 Alkyl, such as methyl, is preferred.

[0083] R 2 is a hydrocarbylene group having up to 12 carbon atoms. By hydrocarbylene is meant a group containing only C and H atoms. It may contain an alkylene chain or a combination of an alkylene chain and a ring, for example a phenylene or cyclohexylene ring. The term "optionally containing an ether or amino linker" means that the carbon chain may be interrupted in the chain by -O- or -NH- groups, for example forming silanes, for example [3-(2,3-epoxypropoxy)propyl]trimethoxysilane: H2COCHCHOCH2CH2CH2Si(OCH3)3. It is preferred that the group Y is not bound to a carbon atom that is bound to such a linker -O- or -NH-.

[0084] Therefore, R 2 may represent -(C6H4)-NH-(CH2)3- or (C6H4)-(CH2)3, etc.

[0085] R 2 is preferably an unsubstituted (with the exception of Y), unbranched alkylene chain having 2 to 8 C atoms, optionally with an ether or amino linker.

[0086] Thus, a preferred silane general formula is structure (V):

[0087] [ka]

[0088] During the ceremony, z' is an integer from 2 to 3; R 3 is an unsubstituted, unbranched alkylene chain having 2 to 8 C atoms, optionally containing an ether or amino linker, Y' is R 3 an amino or epoxy functional group bonded to a group, X' represents an alkoxy group.

[0089] Examples of such silanes are many of the representative products manufactured by Evonik Industries AG and sold under the brand name Dynasylan®, Silquest® silanes manufactured by Momentive, and GENIOSIL® silanes manufactured by Wacker.

[0090] Specific examples include methacryloxypropyltrimethoxysilane (Dynasylan MEMO, Silquest A-174NT), 3-mercaptopropyltri(meth)ethoxysilane (Dynasylan MTMO or 3201; Silquest A-189), (3-glycidoxypropyl)trimethoxysilane (Dynasylan GLYMO, Silquest A-187), (3-glycidoxypropyl)triethoxysilane (Dynasylan GLYEO), tris(3-trimethoxysilylpropyl)isocyanurate (Silquest Y11597), β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (Silquest A-186), γ-isocyanatopropyltrimethoxysilane (Silquest A-Link 35, Geniosil GF40), (methacryloxymethyl)trimethoxysilane (Geniosil XL 33), (isocyanatomethyl)trimethoxysilane (Geniosil XL 43), (3-aminopropyl)trimethoxysilane (Dynasylan AMMO;Silquest A-1110), (3-aminopropyl)triethoxysilane (Dynasylan AMEO) or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (Dynasylan DAMO, Silquest A-1120) or 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-methylpropaneamine (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), Deolink Epoxy TE and Deolink Amino TE (DOG Deutsche Oelfabrik) and mixtures thereof. An oligomeric epoxy silane, Coatosil MP 200 from Momentive, may also be used in the composition.

[0091] Specific silanes include (3-glycidoxypropyl)triethoxysilane (H2COCHCH2OCH2CH2CH2Si(OCH2CH3)3, (3-glycidoxypropyl)trimethoxysilane (H2COCHCH2OCH2CH2CH2Si(OCH3)3).

[0092] Particular preference is given to using the silane (3-glycidoxypropyl)trimethoxysilane. Mixtures of silanes may also be used.

[0093] The amount of silane present in the primer layer composition may be 2.0-15% by weight, preferably 2.5-10% by weight, more preferably 2.5-8.0% by weight, and ideally 3.0-7.0% by weight, based on the total weight. When blends of silanes are used, these percentages refer to the total silane content.

[0094] Thus, by using this amount of silane, the primer layer composition of the present invention reliably adheres to the substrate even if the substrate is wet or rusty when the composition is applied. If the content of silane in the primer layer composition is less than 2.0 wt.%, poor adhesion occurs when the composition is applied to the target substrate.

[0095] [Hardening agent] The primer coating composition of the present invention comprises at least one curing agent. Ideally, it is amine-based and not modified in any way to increase compatibility with water. That is, there are no hydrophilic structural segments, such as polyether segments, in the molecular structure of the curing agent. The curing agent is preferably selected from N-benzylated polyalkyleneamines, amine-epoxy adducts and / or phenalkamines.

[0096] Most preferably, the curing agent is a polyamine containing at least two amino groups. To obtain a crosslinked network, the curing agent must contain at least three "reactive" hydrogen atoms. A "reactive" hydrogen atom refers to a hydrogen atom that transfers from a nucleophile to an oxygen atom of an epoxide during a ring-opening reaction. Thus, the curing active amine group cannot be tertiary. However, tertiary amine-containing compounds may be added to the composition as curing accelerators. The curing agent usually contains at least two curing reactive functional groups.

[0097] In one embodiment, the hardener comprises a benzylamine motif:

[0098] [ka]

[0099] The benzylamine in the curing agent may be optionally substituted on either the ring, the methylene linker, or the N atom, but one active hydrogen must remain. Suitable substituents include C1-15 alkyl groups, OH, O-C1-4-alkyl, halogen, cyano, amine, and alkylamine groups (C1-4-N).

[0100] In a preferred embodiment, the curing agent is a polyamine curing agent that contains one or more benzylamine structures.

[0101] More specifically, the curing agent comprises two or more repeating units, i.e., the curing agent is a polymer or oligomer. The curing agent is preferably a polyamine polymer comprising a benzylamine structure at at least one end of the polyamine polymer chain. The polyamine polymer may comprise a benzylamine structure at both ends of the polymer chain. Each repeating unit may also comprise a benzylamine group. The benzylamine group may be substituted or unsubstituted.

[0102] In a preferred embodiment, the curing agent comprises at least two or more benzylamine structures.

[0103] In one embodiment, the curing agent comprises a benzylated polyalkylene polyamine structure as described in WO2017 / 147138A. The benzylated polyalkylene polyamine structure preferably has a structure as shown below:

[0104] [ka]

[0105] During the ceremony, R 1 is substituted or unsubstituted benzyl; R 2 is R 1or a group independently selected from a hydrogen atom or a C1 to C16 linear, cyclic or branched alkyl group, an alkenyl group and an alkylaryl group; X, Y and Z are independently selected from C2-C10 alkylene groups and cycloalkylene groups, preferably ethylene, propylene, butylene, hexylene, cyclohexyldimethylene and cyclohexylene; y is an integer from 1 to 7; and z is an integer of 0 to 4.

[0106] Examples of suitable benzylated polyalkylene polyamine structures are benzylated polyethylene polyamines, benzylated polypropylene polyamines, benzylated polyethylene-polypropylene polyamines, and combinations thereof.

[0107] Non-limiting examples of polyethylene polyamines include ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA) and other higher polyethylene polyamines. Suitable polypropylene polyamines include, but are not limited to, propylenediamine (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,N'-tris( 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.

[0108] The benzylated polyalkylenepolyamine structure is usually prepared by reductive amination of benzaldehyde, including substituted and unsubstituted benzaldehyde, with polyalkylenepolyamine. Examples of substituted benzaldehyde are benzaldehydes in which the aromatic ring is substituted with one or more halogen atoms, C1-C4 alkyl groups, methoxy groups, ethoxy groups, amino groups, hydroxyl groups or cyano groups. The preferred benzaldehydes are benzaldehyde and vanillin.

[0109] In another embodiment, the curing agent is an amine epoxy adduct, such as an adduct made by reacting a bisphenol A epoxy resin with a primary diamine. The amine epoxy adduct can be synthesized by reacting an epoxy resin with an excess of a primary diamine, for example at 40-100° C. The reaction is typically carried out in a solvent such as n-butanol or benzyl alcohol.

[0110] Preferably, the bisphenol A epoxy resin has an EEW of less than 250 g / eq. Primary diamines suitable for the synthesis of amine epoxy adducts may be ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA) and other higher polyethylene polyamines. Aliphatic primary diamines such as 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,5-diamino-2-methylpentane, 1,6-hexanediamine and 2,2,4(2,4,4)-trimethyl-1,6-hexanediamine may also be used. Primary diamines containing cyclic structures may also be used, such as 1,4-diaminocyclohexane, isophoronediamine (IPDA), 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)benzene, and 1,4-bis(aminomethyl)benzene. In a preferred embodiment, the primary diamine is a mixture of 1,5-diamino-2-methylpentane and isophoronediamine (IPDA).

[0111] The amine-epoxy adduct preferably has an average molecular weight of 500 g / mol to 3000 g / mol, more preferably 600 g / mol to 2000 g / mol.

[0112] In another embodiment, the curing agent is a reaction product of a phenol, formaldehyde, and a primary diamine, such as a Mannich base. The phenol may be an unsubstituted or substituted phenol, such as an alkylphenol, and in one embodiment, the phenol is cardanol. When the phenol is cardanol, the curing agent is called a phenalkamine. Mannich base and phenalkamine curing agents are particularly suitable as curing agents under low temperature conditions, for example below 10°C. Thus, the use of phenalkamine curing agents forms a preferred aspect of the present invention.

[0113] In principle, any primary diamine can be used to synthesize the phenalkamine hardener. Non-limiting examples of primary diamines include ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA) and other higher polyethylene polyamines. Aliphatic primary diamines such as 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,5-diamino-2-methylpentane, 1,6-hexanediamine and 2,2,4(2,4,4)-trimethyl-1,6-hexanediamine. Primary diamines containing cyclic structures, such as isophoronediamine (IPDA), 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethylcyclohexane), 1,3-bis(aminomethyl)benzene and 1,4-bis(aminomethyl)benzene may also be used. Phenalkamines based on 1,3-bis(aminomethyl)benzene and ethylenediamine are preferred.

[0114] In another embodiment, the curing agent is not a polyoxyalkyleneamine, such as a Jeffamine type curing agent.

[0115] In another embodiment, the curing agent is not a ketimine or aldimine. The ketimine or aldimine curing agent comprises the reaction product of a polyalkylpolyamine component and a reactant comprising a ketone or aldehyde component.

[0116] In a preferred embodiment, the curing agent does not comprise a polyoxyalkyleneamine, or a ketimine or aldimine.

[0117] In a preferred embodiment, the curing agent composition is a mixture of the N-benzylated alkylene amine and the amine epoxy adduct as described above, for example, mixed in a weight ratio of 40:60 to 60:40.

[0118] The curing agent composition preferably has an active hydrogen equivalent (AHEW) of 50 to 200 g / eq, more preferably 70 to 150 g / eq, and most preferably 90 to 110 g / eq.

[0119] The number of "active hydrogen equivalents" for one or more curing agents is the sum of the contributions from each of the one or more curing agents. The contribution from each of the one or more curing agents to the active hydrogen equivalent is defined as the number of grams of said curing agent divided by the active hydrogen equivalent weight of said curing agent, where the active hydrogen equivalent weight of a curing agent is determined as the number of grams of curing agent that are equivalent to 1 mole of active hydrogen.

[0120] Preferably, the ratio of the hydrogen equivalent of the entire curing agent to the total epoxy equivalent is in the range of 50:100 to 120:100.

[0121] Particularly preferred epoxy-based coating compositions have a ratio between the active hydrogen equivalent of the curing agent and the epoxy equivalent of the composition in the range of 60:100 to 110:100, such as 70:100 to 105:100, for example 80:100 to 95:100.

[0122] The viscosity of the curing agent composition is preferably 200 to 5000 mPas, more preferably 400 to 2500 mPas, and most preferably 500 to 1500 mPas.

[0123] The curing agent is preferably present in an amount of 5.0-40% by weight of the primer coating composition, such as 8.0-40% by weight of the primer coating composition. More preferably, the curing agent is present in an amount of 10-30% by weight, especially 10-25% by weight of the primer coating composition. When a blend of curing agents is used, these percentages refer to the total curing agent content in the primer layer composition.

[0124] Commercially available curing agents for use in the present invention include Ancamine 1618, Ancamine 2422, Ancamine 2432, Ancamine 2519, Ancamine 2738, Ancamine 2739, Ancamine 2712M from Evonik, and NX-5594, GX-5135, GX-6027, NX-6654, NC-540, NC-541, NC-541LV, LITE 2001, LITE 2001LV and LITE 2002 from Cardolite.

[0125] [solvent] The primer coating composition of the present invention comprises at least one glycol ether solvent. The use of a glycol ether solvent has been found to allow for a long pot life and is essential to allow application of the primer layer composition to wet or rusted substrates. It also acts as a wetting agent for the extenders in the formulation. This solvent therefore ensures that the primer layer composition of the present invention adheres reliably to the substrate even if the substrate is wet or rusted at the time of application of the composition. The glycol ether solvent should be liquid at room temperature and pressure (1 atm, 23°C).

[0126] The glycol ether solvent can be provided as part of component A and / or as part of component B, preferably as component A.

[0127] The glycol ether solvent of the present invention is preferably a solvent of formula (I).

[0128] [ka]

[0129] During the ceremony, x is 1 to 3; R is C1~C 16 is an aliphatic group; R' is C1 to C 16 It is an aliphatic group.

[0130] Preferably, R and R' are independently C1 to C 16 Linear, cyclic or branched alkyl groups, such as C1-C 16 The alkyl group may be straight or branched.

[0131] Preferably, R and R' are independently a C1 to C8 linear, cyclic or branched alkyl group, such as a C1 to C8 linear or branched alkyl group.

[0132] Preferably, R and R' are independently a C1-C6 linear or branched alkyl group. Preferably, R' is an ethylene or propylene repeat unit. Preferably, x is 1 or 2, especially 1. When x is 2 or 3, preferably, all R' groups are the same.

[0133] Preferably, R is a C2 to C8 linear, cyclic or branched alkyl group, such as a C2 to C8 linear or branched alkyl group. Preferably, R is a C2 to C6 linear or branched alkyl group.

[0134] The glycol ether solvent of the present invention is preferably a solvent of formula (II).

[0135] [ka]

[0136] During the ceremony, R is a C1 to C8 linear or branched alkyl group; R' is an ethylene or propylene group.

[0137] In a preferred embodiment, the solvent is ethylene glycol ether or propylene glycol ether, such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, propylene glycol methyl ether, propylene glycol monoethyl ether, propylene glycol n-propyl ether, propylene glycol n-butyl ether, propylene glycol phenyl ether, dipropylene glycol n-propyl ether, dipropylene glycol n-butyl ether or tripropylene glycol n-butyl ether.

[0138] In a preferred embodiment, the solvent comprises propylene glycol n-butyl ether.

[0139] The glycol ether solvent preferably has a boiling point of 250°C or less, preferably 50 to 200°C, for example 90 to 180°C.

[0140] The glycol ether solvent preferably has an Mw (molecular weight) of 50 to 400 g / mol, more preferably 80 to 200 g / mol.

[0141] Other solvents may also be present. Other suitable solvents include aromatic hydrocarbons, aliphatic hydrocarbons, ketones, esters, alcohols, and ethers. Examples of hydrocarbon solvents include toluene, xylene, light aromatic solvent naphtha [C8-C10] (Solvesso 100), mineral spirits, and the like. Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, methyl isoamyl ketone, and the like. Examples of esters include ethyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, tert-butyl acetate, propylene glycol methyl ether acetate, and the like. Examples of alcohols include ethanol, propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, benzyl alcohol, and the like.

[0142] In order to achieve the desired surface resistance and pot life of the coating composition, it is preferred to combine xylene or n-butyl acetate or tert-butyl acetate with the glycol ether solvent. More preferably, for health and safety reasons, the glycol ether solvent is propylene glycol ether. Propylene glycol ether has a good viscosity reducing effect on the composition. Di- and tri-propylene glycol ethers may be used, but (mono)propylene glycol ether is preferred in terms of evaporation rate. Most preferred is propylene glycol n-butyl ether.

[0143] The amount of glycol ether solvent, such as the solvent of formula (I), in the primer coating composition is from 1.0 to 15% by weight, preferably from 1.0 to 10% by weight, more preferably from 2.0 to 8.0% by weight, ideally from 2.0 to 6.0% by weight, based on the total weight of the coating composition. When a blend of glycol ether solvents is used, these percentages refer to the total content of glycol ethers present.

[0144] The total amount of solvent in the primer coating composition is 2.0-15 wt %, preferably 5.0-15 wt %, more preferably 5.0-12 wt %, and ideally 7.0-10.5 wt %, based on the total weight of the coating composition.

[0145] [Microsphere] The primer coating composition of the present invention includes microspheres, such as organic or inorganic microspheres. These microspheres may be coated or uncoated. These microspheres may be hollow or solid. Suitable microspheres are glass beads, uncoated or coated hollow and solid ceramic beads, beads of polymeric materials, such as poly(methyl methacrylate), poly(methyl methacrylate-co-ethylene glycol dimethacrylate), poly(styrene-co-ethylene glycol dimethacrylate), poly(styrene-co-divinylbenzene), polystyrene, poly(vinyl chloride), poly(vinylidene fluoride) and poly(vinylidene chloride).

[0146] Examples of commercially available hollow organic spherical filler particles include Dualite® grades E030, E055, E065-135D, E130-055D, E130-095D, E130-105D, E130-040D, E035-FR, and E135-025D from Chase Corporation.

[0147] Preferably, the primer coating composition comprises solid or hollow inorganic spherical microspheres.Suitable solid or hollow inorganic spherical filler particles are commercially available.Commercially available examples of hollow inorganic spherical filler particles include Glass Bubbles S28HS, Microbubbles H38HS, Fillite Cenosphere, Poraver (expanded glass), Eccospheres, Q-Cel, Sphericel, Thermospheres, Omega spheres (e.g. available from 3M, SMC Minerals, Omya, Poraver, Trelleborg, Potters, Omega) and hollow glass spheres from Hollowlite.

[0148] Preferably, inorganic spherical particulate is hollow. This means that there is a void or cavity in the center of the particle. This void or space is filled with gas, preferably air. The inorganic spherical filler particles preferably used in the present invention are substantially hollow. Therefore, preferably, the volume of void or cavity is at least 70 vol.%, more preferably at least 80 vol.% of the total volume of the particle.

[0149] The density of the microspheres is preferably as low as practical, for example as specified in the technical specifications provided by the supplier, and the density of the microspheres is preferably 0.1 to 1 g / cm 3 , more preferably 0.2 to 0.8 g / cm 3 , and more preferably 0.3 to 0.5 g / cm 3 This is believed to reflect the fact that the particles are not solid but hollow.

[0150] Thus, the microspheres can ensure a low density and high volumetric solids content of the primer layer composition. The use of microspheres, especially hollow microspheres, allows the binder content to be kept low while maintaining a high filler content.

[0151] Preferably, the microspheres present in the coating composition of the present invention have a hydrostatic crush strength of at least 5000 psi, for example as specified by the supplier in a technical data sheet. This is beneficial because it means that the filler particles do not break up during processing, thus maintaining the ability to provide a low density coating composition. It is also advantageous because the microspheres do not change shape and / or size during processing, allowing them to be densely packed and achieve a high build in the final coating formed.

[0152] The microspheres present in the coating composition of the present invention comprise glass, ceramic, or plastic, more preferably comprise glass, ceramic, or plastic. More preferably, the microspheres present in the coating composition of the present invention comprise glass, even more preferably comprise glass, since glass particles provide a good balance of crush strength, hardness, and electrical conductivity. Optionally, the microspheres present in the coating composition of the present invention may be surface treated. Examples of surface treatments include treatments that change the hydrophobicity of the surface, treatments that improve compatibility with binders, and / or treatments that facilitate chemical incorporation into binders. Preferably, the particles are treated with vinyl silane.

[0153] Thus, in a preferred embodiment, the microspheres of the present invention are vinylsilane treated microspheres.

[0154] The microspheres present in the coating composition of the present invention are substantially spherical, and more preferably are spherical, which is advantageous as it allows the particles to be more closely packed in the coating composition of the present invention.

[0155] Alternatively, the D10 diameter of the microspheres is from 1 to 40 μm, more preferably from 5 to 35 μm, and even more preferably from 10 to 30 μm, as determined by ISO 13320:2009 using a Malvern Mastersizer 2000.

[0156] Alternatively, the D50 diameter of the microspheres is from 10 to 80 μm, more preferably from 20 to 70 μm, and even more preferably from 30 to 55 μm, as determined by ISO 13320:2009 using a Malvern Mastersizer 2000.

[0157] Preferably, the D90 diameter of the microspheres is 30-150 μm, more preferably 50-90 μm, and even more preferably 50-80 μm, as determined by ISO 13320:2009 using a Malvern Mastersizer 2000.

[0158] A preferred coating composition of the present invention contains 1.0-9.0 wt. % of microspheres, more preferably 2.0-8.0 wt. %, and even more preferably 2.0-7.0 wt. %, based on the total weight of the composition. If the content of microspheres exceeds the range of claim 1, the composition may fail the cathodic destructive test.

[0159] Thus, this amount of microspheres ensures that the primer layer composition of the present invention provides corrosion protection under the substrate even if the substrate is wet or rusted at the time of application of the composition.

[0160] The microspheres may be provided as part of component A and / or as part of component B, preferably as component A.

[0161] [Hydrocarbon resin] The primer coating composition of the present invention may include a hydrocarbon resin. A wide range of hydrocarbon resins are suitable for inclusion in the coating composition. The hydrocarbon resin may be a petroleum resin or a xylene formaldehyde resin.

[0162] Examples of petroleum resins suitable for the present invention include aromatic petroleum resins obtained by polymerizing C9 fractions (e.g., styrene derivatives such as α-methylstyrene, ο, m, p-cresol, indene, methylindene, cumene, naphthalene or vinyltoluene) obtained from heavy oil by-produced in naphtha cracking, and aliphatic petroleum resins obtained by polymerizing C5 fractions such as 1,3-pentadiene or isoprene, 2-methyl-2-butene, cyclopentadiene, dicyclopentadiene or cyclopentene.

[0163] In addition, the present invention can also employ copolymerized petroleum resins obtained by copolymerizing a C9 fraction with a C5 fraction, aliphatic petroleum resins obtained by cyclopolymerizing a portion of the conjugated dienes of a C5 fraction such as cyclopentadiene or 1,3-pentadiene, resins obtained by hydrogenating aromatic petroleum resins, and alicyclic petroleum resins obtained by polymerizing dicyclopentadiene. It is also possible to use a mixture of diaryl and triaryl compounds obtained by reacting a C9 blend under catalytic conditions.

[0164] Preferably, the hydrocarbon resin is a resin obtained by polymerization of a C9 fraction. The hydrocarbon resin may or may not contain OH functional groups.

[0165] The hydrocarbon resin may have a viscosity of 10 to 10,000 mPas, more preferably 20 to 5,000 mPas, and most preferably 40 to 200 mPas.

[0166] The primer coating composition of the present invention preferably comprises 0-10 wt.% of a hydrocarbon resin based on the total weight of the composition, preferably 2.0-7.0 wt.% based on the total weight of the composition. When a blend of hydrocarbon resins is used, these wt.% refer to the total content of said hydrocarbon resins.

[0167] The hydrocarbon resin may be provided as part of component A and / or as part of component B, preferably as component A.

[0168] Examples of suitable commercially available hydrocarbon resins include Novares TL10, Novares LC15, Novares L100, Novares LA300 from Rain Carbon, Hirenol PL-150, Hikotack LP-9800S from Colon Industries, and Epodil LV5 from Evonik.

[0169] [Reactive diluent] The primer layer coating composition may further comprise a reactive diluent, preferably a reactive diluent formed from a modified epoxy compound.

[0170] Examples of such reactive diluents include phenyl glycidyl ether, alkyl glycidyl ether (number of carbon atoms in the alkyl group: 1 to 16), glycidyl ester of Versatic acid (R 4 R 5 R 6 C-COO-Gly, R in the formula 4 R 5 R 6 is an alkyl group, e.g., C8-C10 alkyl, and Gly is a glycidyl group), olefin epoxide (CH3-(CH2) n -Gly, where n=11-13, 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 alkylphenyl glycidyl ether), such as methylphenyl glycidyl ether, ethylphenyl glycidyl ether, propylphenyl glycidyl ether and glycidyl neodecanoate. Another preferred option is Cardolite NC-513, obtained from the reaction of epichlorohydrin with oil obtained from cashew nut shells.

[0171] Among the above reactive diluents, aliphatic reactive diluents are preferred. The aliphatic reactive diluents are preferably formed from the reaction of a compound containing at least one aliphatic epoxide functional group with an aliphatic alcohol or polyol, such as 1,6-hexanediol diglycidyl ether or 1,4-butanediol diglycidyl ether. Aliphatic glycidyl ethers with a chain length of 8 to 14 are also preferred. The preferred reactive diluents are aliphatic, as they contribute to the flexibility of the coating. The use of p-TBPGE (para-tertiary butyl phenyl glycidyl ether) is also possible.

[0172] Multifunctional rather than monofunctional reactive diluents are preferred as they speed up the drying process and increase crosslink density, which also contributes to better anti-corrosive properties.

[0173] The above reactive diluents can be used alone or in combination of two or more.

[0174] In the total primer layer composition, the reactive diluent is desirably contained in an amount of 0 to 20 wt%, preferably 1.0 to 15 wt%, for example 2.0 to 10 wt%, particularly 2.0 to 7.0 wt%. When a blend of reactive diluents is used, these percentages refer to the total content of reactive diluents.

[0175] By adding the reactive diluent in the above amount, the viscosity of the main primer layer composition is reduced, making it possible to prepare a high solids composition.

[0176] Preferably, the viscosity of the reactive diluent is <100 cP, preferably <50 cP, most preferably <30 cP. Viscosity is at 23° C., 50% RH as determined by the cone and plate method according to ISO 2884-1:2006.

[0177] The epoxy equivalent weight (EEW) of the reactive diluent is preferably 100 to 500 g / eq, more preferably 100 to 300 g / eq, and most preferably 120 to 170 g / eq.

[0178] The reactive diluent may be provided as part of component A and / or as part of component B, preferably as component A.

[0179] [Fillers and pigments] The coating composition optionally includes fillers, color pigments, and anti-corrosive pigments. The fillers include organic and inorganic fillers, which may be of natural origin, i.e., mined or synthetic origin, and may or may not be surface treated.

[0180] Suitable types of inorganic fillers may be selected from the following mineral groups: silicates, phyllosilicates, silica, carbonates, barites, metal oxides, metals, phosphates, halides, sulfides and sulfates. The organic fillers may include organic polymers or polymer blends, graphite, graphene, graphene oxide, fullerenes, carbon nanotubes, carbon fibers, and organic polymer particles, core-shell particles comprising organic compounds such as dyes, resins and / or organic liquids.

[0181] Non-limiting examples of fillers that can be used in the coating composition according to the present invention are nepheline cynthite, talcum, plastrite, chlorite, chrysolite, mica, pyrophyllite, feldspar, bentonite, kaolin, mica / muscovite, clay, wollastonite, quartz, cristobalite, glass flake, glass fiber, fumed silica, calcium silicate, pumice, diatomaceous earth, calcium carbonate, magnesium carbonate, calcium sulfate, dolomite, barium sulfate, iron oxide, fine iron oxide, zinc oxide, aluminum oxide, aluminum hydroxide, aluminum flake, zinc flake, and solid silicone resins, which are generally condensed branched polysiloxanes. Some fillers, such as fumed silica and clay, may have a thickening effect on the coating composition. Inorganic core-shell particles containing organic compounds, such as dyes, resins and / or organic liquids, may also be used.

[0182] Examples of preferred fillers are talc, feldspar, barium sulfate, wollastonite, mica, dolomite, calcite. Particularly preferred are combinations of talc and dolomite (or calcite), such as talc and dolomite, or talc and calcite, or mixtures of dolomite, calcite and talc.

[0183] The color pigment may be an inorganic pigment, an organic pigment, or a mixture thereof. The pigment may be surface treated.

[0184] Representative examples of pigments include black iron oxide, red iron oxide, yellow iron oxide, titanium dioxide, zinc oxide, carbon black, graphite, red molybdate, yellow molybdate, zinc sulfide, antimony oxide, sodium aluminum sulfosilicate, quinacridone, phthalocyanine blue, phthalocyanine green, indanthrone blue, aluminum cobalt oxide, carbazodioxazine, isoindoline orange, bisacetoacetotridiol, benzimidazolone, quinaphthalone yellow, isoindoline yellow, tetrachloroisoindolinone, quinophthalone yellow, metal flake materials (e.g., aluminum flakes, etc.). In a preferred embodiment, the titanium dioxide is surface tread treated with a silicone compound, a zirconium compound, an aluminum compound, or a zinc compound.

[0185] The coating composition may contain anti-rust pigments and / or additives to improve the anti-rust performance. The types of anti-rust pigments and additives are not particularly limited, and any suitable anti-rust pigments and additives may be used. The anti-rust pigments may be based on a combination of a metal or metal cation, such as zinc, aluminum, molybdenum, calcium, strontium, aluminum magnesium, barium, and the like, with a borate, borosilicate, phosphate, orthophosphate, polyphosphate, phosphosilicate, or silicate. The anti-rust pigments may be modified, such as surface modified, and / or may contain complex ions or chelates.

[0186] Non-limiting examples of suitable anti-rust additives may be imidazoles (either in pure form or contained in a polymer or resin matrix) polymers and other organic materials such as C12-14-(tert)-alkylamines, (2-benzothiazolylthio)-butanedioic acid, 4-oxo-4-p-tolylbutyric acid, adducts with 4-ethylmorpholine, (2-benzothiazolylthio)butanedioic acid, poly(3-ammoniumpropylethoxysiloxane) dodecanoate, ammonium benzoate and morpholine.

[0187] Examples of suitable commercially available anti-corrosive pigments and additives include: Halox 520, Halox 570, Halox 630, Halox 350, Halox 430, Halox 700, and Halox BW-11 from Halox Corporation. Haloz BW-191, Haloz CW-314, Haloz CW-491, Haloz CZ-170, Halox SW-111, Haloz SZP-391, Halox SZP-395, Haloz Z-Plex 111, Haloz Z-Plex 250 and Haloz Z-Plex 750 from Haloz; Habicor CS, Habicor Si, Habicor ZS, Habicor ZA, Habicor ZN, Habicor ZO, Habicor ZM, Habicor AZ, Habicor SP, Habicor CP4295, Habicor, Habicor ZP3850, Habicor ZP3860, Habicor 1000 and Habicor 1001 from Habicor; and AX1 from Hexigone.

[0188] The coating composition may comprise 0-15% by weight, for example 0.1-10% by weight, of anti-rust pigments / additives. The coating composition may comprise 0-10% by weight of zinc phosphate and / or calcium phosphate.

[0189] Pigments and fillers may be added to the coating composition in powder form or as a slurry or concentrate.

[0190] The amount of at least one filler or pigment is preferably in the range of 0.05 to 50% by weight, preferably in the range of 1 to 45% by weight, more preferably 5 to 40% by weight, and even more preferably 10 to 40% by weight, based on the total weight of the coating composition.

[0191] [Additives] The coating composition of the present invention optionally includes one or more additives. Examples of additives that may be present in the coating composition of the present invention include rheology modifiers such as thixotropic agents, thickeners and anti-settling agents, dispersants, wetting agents, defoamers, and plasticizers. Suitable additives are not necessarily limited to additives developed and sold for paints. Additives developed and sold for use in adhesives, building materials, plastics / resins, drilling fluids, paper coatings, pigment concentrates, etc., may also be used if compatible with the coating composition. The efficiency of an additive used in a coating composition can be greatly affected by other ingredients and additives contained therein, so it is important to determine the appropriate additive type and concentration by testing. In many cases, it may be necessary and / or useful to add multiple different additives of any type, i.e., two or more defoamers or two or more rheology modifiers, to achieve the desired properties / efficiencies.

[0192] Defoamers and air release additives (herein simply referred to as defoamers) are commonly used in epoxy coatings to aid in the release of air entrapped during the preparation and application of the coating composition. The type of defoamer is not particularly limited, and any suitable type can be used. Common defoamers can be divided into mineral oil-based defoamers, silicone-based defoamers, and polymer-based defoamers. Commercially available defoamers often contain mixtures of these types in combination with solvents and solid particles. Non-limiting examples of defoamers that can be used 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, B yk-051N, Byk-052N, Byk-053N, Byk-054, Byk-055, Byk-057, Byk-070, Byk-072, Byk-077, Byk-081, Byk-08 5, Byk-088, Byk-092, Byk-093, Byk-094, Byk-141, Byk-1610, Byk-1611, Byk-1615, Byk-1616, Byk-1617, By k-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-179 7, Byk-1799, Byk-A515, Byk-A525, Byk-A530, Byk-A535, Byk-A550, Byk-A555 and Byk-A560, Tego from Evonik Airex 901 W, Tego Airex 901 WN, Tego Airex 902 W, Tego Airex 902 WN、This Airex 904 W、This Airex 904 WN、Airase 4500、Airase 4655、Airase 5355、Airase 5655、Airase 8070、Surfonyl 104、Surfonyl 107L、Surfonyl 420、This Foamex 3062、This Foamex 8050、This Foamex 843、This Foamex 844、This Foamex 845 This Foamex 883、This Foamex 1488、This Foamex 810、This Foamex 811、This Foamex 812、This Foamex815、Tego Foamex822、Tego Foamex 823およびTego Foamex 825であってもよい。

[0193] Rheology modifiers can be employed to adjust the rheological profile of the coating composition to prevent settling and floating problems, as well as to adjust flowability and improve sag resistance, workability, application properties, and stabilization of pigment and extender particles. The type of rheology modifier is not particularly limited, and any suitable rheology modifier can be used, but should be selected based on which properties need to be improved and compatibility with the rest of the formulation. Non-limiting examples of suitable rheology modifiers include organically modified clays such as bentonite, hectorite, and attapulgite clays, unmodified clays, organic wax thixotropes based on castor oil and castor oil derivatives, amide waxes, acrylics, ureas, modified ureas, polyurethanes, rheology modifiers based on amide or polyamide backbones, and fumed silica. The active ingredient of the rheology modifier may be modified with functional groups such as polyether groups or alcohol groups, or surface treated with silanes, as is common with fumed silica. Non-limiting examples of commercially available rheology modifiers include TS-610, TS-530, EH-5, H-5, and M-5 from Cabot, Aerosil® R972, Aerosil® R974, Aerosil® R976, Aerosil® R104, Aerosil® 200, Aerosil® 300, Aerosil® R202, Aerosil® R208, Aerosil® R805, Aerosil® R812, Aerosil® 816, Aerosil® R7200, Aerosil® R8200, Aerosil® R9200, Aerosil® R711 from Evonik, and Bentone from Elementis. SD2, Exilva from Borregard, Crayvallac ultra and Crayvallac LV from Arkema. Preferably the rheology modifier comprises micronised amide wax and / or fumed silica and / or clay.The rheology modifier is preferably present in the composition of the present invention in an amount of 0 to 10 wt %, more preferably 0.1 to 6 wt %, and even more preferably 0.1 to 3.0 wt %, based on the total weight of the composition.

[0194] Wetting agents and dispersants can be added to coating compositions to promote dispersion and wetting of pigment and filler particles, thus helping to break up agglomerates during manufacture, preventing reagglomeration and settling in wet paints, preventing the formation of Benard cells in cured paints, reducing paint viscosity, and improving color strength and color stability. Wetting agents and dispersants may be nonionic, cationic, anionic, or may include mixtures of the foregoing. Additionally, wetting agents and dispersants may consist of polymeric or nonpolymeric organic molecules, or mixtures thereof. Non-limiting examples of suitable types of wetting agents and dispersants include fatty acids, lecithins, polysorbates, polyacrylamides, polyether carboxylates, polycarboxylates, polyalkylene glycols, polyethers, and polyacrylates. Non-limiting examples of commercially available wetting and dispersing agents may be Disperbyk-102, Disperbyk-106, Disperbyk-109, 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. Preferably, the wetting and dispersing agent comprises soy lecithin. Preferably, the wetting and dispersing agent is present in an amount of 0-1.5% by weight, more preferably 0.1-1% by weight.

[0195] From another aspect, the present invention comprises: (i) 5.0 to 40 weight percent of an epoxy resin; (ii) 2.0 to 15 wt. % silane; (iii) a hardener; (iv) 1.0 to 15 weight percent of a glycol ether solvent; (v) 1.0-9.0 wt.% microspheres; (vi) 0 to 10 weight percent of a hydrocarbon resin; and (vii) providing a primer coating composition comprising 0 to 20 weight percent of a reactive diluent;

[0196] From another aspect, the present invention comprises: (i) 10 to 40% by weight of an epoxy resin; (ii) 2.5 to 10 wt. % silane; (iii) a hardener; (iv) 1.0 to 10 weight percent of a glycol ether solvent; (v) 1.0-9.0 wt.% microspheres; (vi) 0 to 10 weight percent of a hydrocarbon resin; and (vii) providing a primer coating composition comprising 0 to 15 weight percent of a reactive diluent;

[0197] From another aspect, the present invention comprises: (i) 10 to 40% by weight of an epoxy resin; (ii) 2.5 to 8.0 wt. % silane; (iii) a hardener; (iv) 2.0 to 8.0 wt. % of a glycol ether solvent; (v) 2.0-8.0 wt.% microspheres; (vi) 0 to 10 weight percent of a hydrocarbon resin; and (vii) providing a primer coating composition comprising 0 to 15 weight percent of a reactive diluent;

[0198] From another aspect, the present invention comprises: (i) 10 to 40% by weight of an epoxy resin; (ii) 2.5 to 8.0 wt. % silane; (iii) a hardener; (iv) 2.0 to 6.0 wt. % of a glycol ether solvent; (v) 2.0-7.0 wt.% microspheres; (vi) 0 to 10 weight percent of a hydrocarbon resin; and (vii) providing a primer coating composition comprising 2.0 to 10 weight percent of a reactive diluent;

[0199] [Production of the primer composition] The primer composition can be prepared by any suitable technique commonly used in the field of paint manufacturing. Thus, the various components can be mixed together using high speed dispersers, ball mills, pearl mills, three-roll mills, in-line mixers, etc. The microspheres are preferably added at the let-down stage of the preparation of the coating composition. The paint according to the invention may be filtered using bag filters, Patron filters, wire gap filters, wedge wire filters, metal edge filters, EGLM Ternoclean filters (ex Cuno), DELTA strain filters (ex Cuno), Jenag strainer filters (ex Jenag) or by vibration filtration.

[0200] The primer composition used herein is conveniently prepared by mixing the components. As an example, the first composition (component A) and the hardener composition (component B) can be mixed by adding the hardener component B to the epoxy component A and stirring well until the mixture is homogeneous. The mixture is ready to be applied immediately, for example by spray application, but may be given an induction time before application. The mixing ratio is easily determined by those skilled in the art before mixing the components based on the target percentage in the final primer layer composition, the amount and equivalent of the epoxy functional compound in component A, and the amount and equivalent of the active H-containing compound (primary and secondary amine-containing compound) in component B.

[0201] [Application of the primer composition] The primer composition can be applied to the substrate (especially the steel structure) by well-known standard application methods such as conventional air spray, or airless spray equipment or airmix spray equipment or 2K airless spray pump (or alternatively by brush or roller, especially when used as a stripe coat). Preferably, the composition is applied at ambient conditions without preheating the coating composition.

[0202] The substrate may be wet or moist, or rusted, or both, for example flash rusted.

[0203] [Film thickness] The coating is typically applied to a total dry film thickness of 75-800 μm, preferably 100-500 μm, e.g. 150-350 μm. The dry film thickness of the primer layer is preferably at least 100 μm. The applied film thickness may vary depending on the nature of the substrate to be coated and the expected exposure scenario. The desired film thickness may require the application of multiple coats of the composition, e.g. 2 coats.

[0204] [Cure] Once the coating is applied to a substrate, the coating must be cured. The primer layer cures naturally. Although radiation or heat can be used to accelerate the cure, the compositions of the present invention cure at room temperature without further intervention.

[0205] Although it is preferred to apply it all at once, the volatile content of the coating of the present invention is so low that it is possible to apply further coatings while the primer layer is "wet". Thus, it is not necessary to wait for the first coating to cure before applying the next coating. It is known to apply multiple layers of primer coatings to build up thickness, but traditionally each layer is cured (dried) before applying the next layer. In the present invention, the application of further layers can be done on the wet (or uncured) primer layer. This speeds up the application process.

[0206] Thus, in a further aspect, the invention includes a process in which a further coat of the primer layer coating composition is applied to the undercoat of the primer layer composition without an intermediate curing step. Alternatively, the invention includes a process in which a further coat of the primer layer coating composition is applied to the undercoat of the primer layer composition before the undercoat is cured.

[0207] The invention will now be described with reference to the following non-limiting examples.

[0208] [Analysis method] General Procedure for Preparation of the Compositions Component A of the primer layer was prepared by mixing all the indicated components (parts by weight) in a conventional manner known to those skilled in the art. Component A was then mixed with component B prior to application. The primer layer is typically applied to the steel substrate by airless spray.

[0209] <Calculation of density, volume percent solids, volume concentration of volatile organic compounds and pigments> The density, volume percent solids (volume percent solids), and theoretical volatile organic compound (VOC) content of the compositions were calculated according to ASTM D5201-05a(2020).

[0210] The pigment volume concentration (PVC) of the composition was determined by calculation according to the formula PVC=((Vp+Vf) / (Vp+Vf+Vb))*100. Here, Vp is the volume of the pigment, Vf is the volume of the filler including the glass spheres, and Vb is the volume of the binder.

[0211] <Viscosity measurement> The viscosity of the binder and coating composition was measured in accordance with ISO 2884-1:2006 (ASTMD4287) at a temperature of 23°C, 50% RH, and a viscosity measurement range of 0 to 10P and 10,000s. -1 Measure using a cone-and-plate viscometer set at 0.5. Stormer viscosity (KU) was measured using a Stormer viscometer at 23° C. according to ASTM D562.

[0212] <Cathode Destruction Test> Cathodic destructive testing was carried out according to ASTM G8. The test duration was 30 days. The compositions were applied to sandblasted carbon steel panels with dimensions 150 x 75 x 3 mm with a wet film thickness corresponding to a dry film thickness (DFT) of 2 x 150 μm with a cleanliness of Sa2 1 / 2. The coatings were cured at room temperature for 7 days prior to cathodic destructive testing.

[0213] Adhesion testing of coatings applied to wet substrates Peel adhesion tests were performed according to ISO4624:2016. The compositions were applied to wet sandblasted carbon steel panels with dimensions 150 x 75 x 3 mm at a wet film thickness equivalent to a dry film thickness (DFT) of 2 x 150 μm. The wet panels were prepared by immersing the sandblasted carbon steel panels in water, allowing the water to drip off, and then immediately applying the coating. The difference in mass between the dry and wet panels and the surface area of ​​the panels determined that the residual moisture of the wet panels was 40-45 g. / m 2 The cleanliness of the steel panels before water immersion was Sa2 1 / 2. The coatings were allowed to cure at room temperature for 7 days before peel adhesion testing.

[0214] [Example] The following materials were used:

[0215] [Table 1]

[0216] [Table 2]

[0217] [Table 3]

[0218] [Table 4]

[0219] In Table 4 above, the theoretical physical parameters of the coating compositions can be compared with the measured viscosities. The results show that CE1, which does not contain glass spheres, has higher VOCs and density than E1-E4. CE3-CE5 have a higher viscosity than 2000mPas 1 hour after mixing components A and B, meaning that these compositions have a shorter pot life than the other compositions. These compositions lack glycol ether (CE3), silane (CE4) or contain low levels of silane (CE5). Thus, the pot life of CE3-CE5 shows that high viscosity can be achieved more quickly by using low levels of silane, or by using n-butanol instead of glycol ether.

[0220] The results of the cathodic destructive test and adhesion test are shown in Table 5. The results of the cathodic destructive test were rated on a scale of 1 to 3 based on the following criteria: 1: No blister, peeling up to 3mm - good 2: No blister, 3~8mm peeling - OK 3: No blister and / or melting >8mm - FAIL

[0221] The results of the peel adhesion test on wet and moist substrates were rated on a scale of 1 to 3 based on the following criteria: 1: Poor adhesion of the first or second coat 2: Partial (0-50%) adhesion failure between the substrate and the first coat, remaining cohesion failure 3: Adhesion failure between the substrate and the first topcoat is 50% or more. Options 2 and 3 will "fail" the adhesion test.

[0222] [Table 5]

[0223] Good adhesion between the substrate and the primer coating is important for the performance of an anti-corrosive primer, therefore, if the composition fails the adhesion test, it is deemed unsuitable for use as a high performance anti-corrosive primer.

[0224] Adhesion test results show that the silane and glycol ether solvent are essential for adhesion to wet substrates. Example 3 shows that a xylene-free formulation can be used.

[0225] If the amount of glass spheres is too high (CE2), the formulation fails the cathodic destruction test. Since CE2 failed the G8 test, it was not subjected to further testing on wet substrates. Similarly, CE3 failed the wet substrate test, so it was not an interesting composition for this type of primer coating and was not subjected to cathodic destruction testing.

[0226] The primer compositions of the present invention (Examples 1-4) can be applied to damp or wet surfaces, and can also be applied to rusted or flash-rusted substrates.

Claims

1. (i) epoxy resin; (ii) 2.0 to 15 wt. % of a silane; (iii) a curing agent, such as an amine-based curing agent; (iv) glycol ether solvents; and (v) A primer coating composition comprising 1.0 to 9.0 weight percent microspheres.

2. 2. The primer coating composition of claim 1, wherein said microspheres have a D90 diameter, determined according to ISO 13320:2009 using a Malvern Mastersizer 2000, of 30 to 150 μm, more preferably 50 to 90 μm, even more preferably 50 to 80 μm.

3. 10. The primer coating composition of any of the preceding claims, further comprising a reactive diluent.

4. 10. The primer coating composition of any of the preceding claims, wherein the epoxy resin is a liquid.

5. 10. A primer coating composition according to any of the preceding claims, wherein the epoxy resin is bisphenol based, preferably bisphenol A based.

6. 10. The primer coating composition of any of the preceding claims, wherein the glycol ether solvent is represented by formula (I): 【Chemistry 9】 [In the formula, x is 1 to 3; R is C 1 ~C 16 is an aliphatic group; R' is C 1 ~C 16 It is an aliphatic group.

7. 10. A primer coating composition according to any of the preceding claims, wherein the glycol ether solvent is shown in formula (II), preferably propylene glycol n-butyl ether. 【Chemistry 10】 [In the formula, R is C 1 ~C 8 is a linear or branched alkyl group; R' is an ethylene or propylene group.

8. 10. The primer coating composition of any of the preceding claims, wherein the microspheres comprise glass spheres.

9. 10. A primer coating composition according to any of the preceding claims, wherein the silane is an epoxy silane.

10. 10. A primer coating composition according to any of the preceding claims, wherein the curing agent comprises an N-benzylated polyalkyleneamine or phenalkamine, in particular a phenalkamine based on 1,3-bis(aminomethyl)benzene and ethylenediamine.

11. 10. A primer coating composition according to any preceding claim, wherein the viscosity of the composition immediately after formation is from 200 to 1000 mPas at 23°C.

12. A primer coating composition according to any preceding claim, wherein the glycol ether solvent is present in an amount of from 1.0 to 10% by weight of the composition.

13. 10. A primer coating composition according to any preceding claim, having a pot life at 23°C of at least 30 minutes.

14. 10. The primer coating composition of any preceding claim having a VOC of 220 g / L or less.

15. (i) 10 to 40 wt. % of an epoxy resin; (ii) 2.5 to 10 wt. % of a silane; (iii) a curing agent; (iv) 2.0 to 10 wt. % of a glycol ether solvent; (v) 2.0 to 9.0 wt. % microspheres; (vi) 0 to 10 wt % (e.g., 2.0 to 10 wt %) of a hydrocarbon resin; and (vii) 0 to 15 wt % (e.g., 2.0 to 15 wt %) of a reactive diluent; A primer coating composition according to any of the preceding claims.

16. (i) epoxy resin; (ii) silane; (iv) glycol ether solvents; and (v) component (A) comprising microspheres; and component (B) comprising at least one curing agent; A kit for producing the primer coating composition according to any one of claims 1 to 15.

17. A metal substrate having applied thereon a primer coating composition according to any one of claims 1 to 15.

18. Use of a primer coating composition according to any of claims 1 to 15 for application to wet and / or rusty substrates.

19. 1. A method of coating on a wet metal substrate, the method comprising: 1) blending component A with component B, Component (A) comprises an epoxy resin; Component (B) comprises a curing agent; blending at least one of components (A) or (B) comprising a silane, a glycol ether solvent, and microspheres such that when components (A) and (B) are combined the resulting composition comprises 2.0 to 15 weight percent silane and 1.0 to 9.0 weight percent microspheres; 2) applying the composition to a wet substrate; 3) forming the composition into a film and curing it.

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