Low temperature curing coating composition

Abstract

The present invention relates to a coating composition comprising a binder component and a curing component. The binder component comprises an epoxy resin and the curing component comprises an alicyclic amine and an aromatic Mannich base curing agent. The alicyclic amine and the aromatic Mannich base curing agent each have a primary amine group, a secondary amine group, or both. The weight ratio of the aromatic Mannich base curing agent to the alicyclic amine curing agent ranges from 0.01: 1.00 to 1.70: 1.00. In addition, the aromatic Mannich base curing agent is derived from an aldehyde, a phenolic compound and an amine comprising at least one aromatic ring. In addition, the proportion of the alicyclic amine and the aromatic Mannich base is 70% by weight or more based on the total amount of the curing agent.

Description

Technical Field

[0001] The present invention relates to coating compositions that can be cured at low temperatures. In particular, the present invention relates to low-temperature curable coatings suitable for use as protective linings for the inner surfaces of storage tanks and reservoirs for storing or transporting water or chemicals. Background Art

[0002] Chemical reservoirs come into contact with a wide variety of compounds. Their inner surfaces are typically provided with a coating to protect the surface against the chemicals and also to protect the stored chemicals themselves against contamination that may be present on the surface of the reservoir - from corroded portions of the surface or from residual amounts of previously stored chemicals.

[0003] WO2012 / 119968 describes a coating composition comprising an epoxy resin mixture, a curing agent, an accelerator or a mixture of accelerators, and one or more fillers or pigments, wherein the epoxy resin mixture comprises 60 - 80 wt% RDGE epoxy resin and 20 - 40 wt% epoxy novolac resin. The coating composition is described as a storage tank lining composition.

[0004] WO2015 / 082409 relates to a method of coating metal or concrete surfaces of chemical equipment using an epoxy-based composition that also includes an organosilane or an organosiloxane.

[0005] WO2015 / 165808 and WO2017 / 068015 relate to methods of coating metal or concrete surfaces of chemical equipment using an epoxy-based composition that includes an organoboron compound.

[0006] US2020 / 0362195 relates to a protective coating comprising an epoxy resin and one or more amine curing agents such as diaminocyclohexane.

[0007] US2017 / 0327684 describes a low-viscosity liquid epoxy resin composition comprising two or more curing agents selected from aliphatic polyamines, modified aliphatic polyamines, cyclic amines, and secondary or tertiary amines.

[0008] US4185132 describes the application of epoxy-based road markings to paved surfaces, wherein a combination of an alicyclic amine and an aliphatic polyfunctional amine is used.

[0009] KR10-2021-0047777 describes a solvent-free epoxy coating composition comprising a mixture of an aliphatic amine resin and an alicyclic amine resin.

[0010] JP2001163955 describes an epoxy resin composition comprising bis(aminomethyl)cyclohexane or modified bis(aminomethyl)cyclohexane, a fatty amine compound, and a curing accelerator.

[0011] CN102816502 relates to a room-temperature curable coating especially containing linear phenolic epoxy resin, a modified aromatic amine curing agent (such as cardanol aromatic polyamine curing agent) and an alicyclic amine curing agent.

[0012] WO2006 / 045407 relates to an epoxy resin curable at ambient temperature that can be used in coatings, containing aromatic halogenated glycidyl ether resin, non-halogenated glycidyl ether resin and aliphatic, alicyclic or aromatic amine.

[0013] WO2019 / 170563 relates to an epoxy curing agent containing two or more amine components, wherein one amine component is N-(3-aminopropyl) cyclohexylamine and the other amine component is a hydrogenated product with an oligomeric structure from the 4,4'-methylenedianiline process.

[0014] WO2017 / 184514 relates to a two-component epoxy resin paint containing a polyamide curing agent and at least one Mannich base curing agent, and one or both of these two curing agents are derived from one or more polyfunctional amines containing at least one alicyclic polyfunctional amine.

[0015] WO2014 / 093115 relates to a curable coating composition containing at least two epoxy resins and at least one amine curing agent, wherein one of the epoxy resins is 1,4-cyclohexanedimethanol resin.

[0016] WO2011 / 059500 relates to a curable composition containing an epoxy component and a hardener component, wherein the epoxy component contains an aromatic epoxide and a polymeric glycidyl ether reactive diluent and the hardener component contains an adduct and a Mannich base curing agent.

[0017] EP1810985 describes a curable composition containing an epoxy resin having more than one epoxy group per molecule on average and a curing agent, and the curing agent contains the reaction product of a diglycidyl ether or a monoglycidyl ether with a composition containing volatile monoamines and polyamines. The curing agent also optionally contains polyamines and optionally contains polyphenolic novolac.

[0018] BE799277 relates to a fast-curing epoxy-based coating composition or molded article containing isophorone diamine and an aminophenol compound, especially an aminophenol based on bisphenol A and diethylenetriamine.

[0019] The abstract (English translation) of the article "MXDA type corrosion-resistant epoxy resin coatings" by Mine, Shigeo in Toso to Toryo (1992), 493, 45 - 58 describes a composition for an inner coating of a methanol transport tanker, comprising an epoxy resin and an MXDA-based Mannich type hardener.

[0020] KR10 - 2276827 relates to an epoxy-based anticorrosive composition suitable for building-based substrates such as steel parts for bridges or concrete structures, and the curing agents that can be used include polyamines such as polyethylene diamine, isophorone diamine, and Mannich bases.

[0021] US10,214,612 relates to an epoxy resin composition comprising at least one epoxy compound and a hardener composition, wherein the hardener contains 2-(2,2,6,6-tetramethylpiperidin-4-yl)-1,3-propanediamine.

[0022] A common problem faced by protective coatings is their long curing time at low temperatures, for example where these compositions are applied in places experiencing cold conditions, such as during winter in higher northern or southern latitudes.

[0023] EP2159218 describes an amine composition for curing epoxy resins, which amine composition contains dimethyl m-xylenediamine and at least one polyfunctional amine. The curing temperature can be room temperature or below, for example, less than or equal to 5°C.

[0024] However, there is still a need for other protective coating compositions that can be applied at lower temperatures but have a sufficiently short curing time to make them commercially and technically viable. Summary of the Invention

[0026] The present invention relates to a coating composition comprising a base component and a curing component.

[0027] The base component contains an epoxy resin, and the curing component contains an alicyclic amine and an aromatic Mannich base hardener. The alicyclic amine and the aromatic Mannich base hardener each have a primary amine group, a secondary amine group, or both.

[0028] The weight ratio of the aromatic Mannich base hardener to the alicyclic amine hardener is at least 0.01:1 and also does not exceed 1.7:1, for example, does not exceed 1.5:1.

[0029] The proportion of the alicyclic amine hardener and the aromatic Mannich base hardener is 70% by weight or more based on the total amount of the hardeners in the coating composition.

[0030] The aromatic Mannich base curing agent is derived from an aldehyde, a phenolic compound, and an amine containing at least one aromatic ring.

[0031] The present invention also relates to a substrate coated with the composition, which in an embodiment is the inner surface of a reservoir for storing or transporting chemicals or water.

[0032] The present invention further relates to a method of coating a substrate, in which the above coating composition is applied to the substrate and cured. In an embodiment, the curing temperature is 5 °C or lower, for example 0 °C or lower.

[0033] Description of Embodiments

[0034] In the following discussion, aliphatic hydrocarbon groups and alkyl groups will be mentioned. These can be linear, branched, or cyclic, or can contain both cyclic and acyclic moieties. Aliphatic groups and aryl groups can also contain substituents and / or ring heteroatoms as further described below.

[0035] [Coating Composition]

[0036] The coating composition can be provided in a two-component form, where one part (Part A) contains a curable epoxy resin and the other part (Part B) contains a curing agent. They can be mixed immediately before application to provide the coating composition, which subsequently cures to form a protective coating film.

[0037] The coating compositions of the present invention are particularly suitable for low-temperature application, so they can still be effectively cured at low temperatures, especially below zero. Therefore, they have a drying time fast enough for use at low temperatures without sacrificing workability characteristics such as pot life, gel time, and viscosity.

[0038] Once cured, the coating composition can be a protective lining, such as a chemical-resistant lining. In an embodiment, it can be a protective lining for the inner surface of a fixed or mobile storage tank or reservoir (including associated pipelines) for storing or transporting water or chemicals, such as liquid chemicals. Examples of fixed storage tanks or reservoirs include those associated with chemical manufacturing sites, crude oil processing sites (refineries), offshore crude oil production sites, and floating production, storage, and offloading (FPSO) facilities. Examples of mobile tanks or reservoirs include tank trucks, railway tank cars, oil tankers, and barges.

[0039] [Epoxy Resin]

[0040] The coating composition contains at least one epoxy resin. Suitable epoxy resins include those containing one or more aromatic rings (sometimes called aromatic epoxy resins), examples of which include phenol novolac epoxy resin, cresol novolac epoxy resin, bisphenol A epoxy resin, bisphenol S epoxy resin, and bisphenol F epoxy resin.

[0041] Examples include diglycidyl ethers of bisphenol A, F or S, diglycidyl ethers of hydrogenated bisphenol A, F or S, condensation or chain-extended glycidyl ethers of any of the above bisphenols (such as novolac resins) or hydrogenated condensation glycidyl ethers of bisphenols.

[0042] In one embodiment, the epoxy resin (or at least one of the epoxy resins) is a phenol novolac epoxy resin. Suitable phenol novolac epoxy resins include DEN TM 425, DEN TM 431 and DEN TM 438 (purchased from DOW Chemicals), Epon TM 154, Epon TM 160, Epon TM 161 and Epon TM 162 (purchased from Momentive Performance Chemicals) and Epalloy TM 8250 (purchased from Emerald Chemical Co.). Other epoxy resins that can be used include cresol novolac epoxy resins such as Epon TM 164 and Epon TM 165 (purchased from Momentive Performance Chemicals), or bisphenol A novolac resins such as Epon TM SU series resins.

[0043] In another embodiment, the epoxy resin (or one of the epoxy resins) is a bisphenol-based epoxy resin, such as a diglycidyl ether of a bisphenol, such as diglycidyl ethers of bisphenol A, F or S. In other embodiments, the epoxy resin (or at least one of the epoxy resins) is a bisphenol F epoxy resin such as a diglycidyl ether of bisphenol F. Suitable bisphenol F epoxy resins include DER TM 354 (purchased from DOW Chemicals) or Epikote TM 862 (purchased from Momentive performance Chemicals).

[0044] In an embodiment, the epoxy equivalent weight of the epoxy resin is in the range of 165 - 185 g / eq. The epoxy equivalent weight is the weight of the epoxy resin required to produce 1 mole (or 1 equivalent) of epoxy functional groups.

[0045] Any blends of the above epoxies can be used in combination with each other, but phenol novolac epoxy resin or bisphenol F epoxy resin is usually used when very high chemical resistance is required, and in embodiments they account for at least 50% of the epoxy resin, calculated based on the total number of epoxy groups provided by the epoxy resin. In other embodiments, the phenol novolac epoxy resin or bisphenol F epoxy resin accounts for at least 60% of the epoxy resin, such as at least 70% or at least 80%, calculated based on the total number of epoxy groups provided by the epoxy resin.

[0046] To minimize the solvent content of any coating composition, the epoxy resin source (such as phenol novolac epoxy resin or bisphenol F epoxy resin) can have a low solvent content, such as less than 20% by weight or less than 10% by weight based on the weight of the epoxy resin. In embodiments, the epoxy resin is solvent-free.

[0047] The amount of epoxy resin in the coating composition can range from 5 - 50% by weight, such as 8 - 30% by weight.

[0048] [Curing agent]

[0049] The coating composition contains two different curing agents. One is an alicyclic amine curing agent and the other is an aromatic Mannich base curing agent.

[0050] The alicyclic amine curing agent can be selected from monomeric, dimeric, oligomeric or polymeric alicyclic amines, or a mixture of any two or more thereof.

[0051] Examples of monomeric alicyclic amines include p-aminodicyclohexylmethane (or bis(4-aminocyclohexyl)methane, usually abbreviated as PACM), 2,4'-diaminodicyclohexylmethane, 2,2'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, bis(4-amino-3-methylcyclohexyl)methane, N-cyclohexyl-1,3-propanediamine, 1,2-diaminocyclohexane, N-aminoethylpiperazine, 3-(cyclohexylamino)propylamine, piperazine, N-aminopiperazine, 4-methylcyclohexane-1,3-diamine, isophorone diamine and 1,3-bis(aminomethyl)cyclohexane.

[0052] The alicyclic amine curing agent usually does not contain an aromatic structural moiety, for example it does not contain a mixture of aliphatic and aromatic rings.

[0053] In embodiments, the alicyclic amine curing agent has at least two active hydrogens per molecule on average. The amine groups usually have at least one primary or secondary amine group, and in embodiments, all amine groups are primary or secondary amine groups. An amine curing agent having more than one nitrogen atom can be called a polyamine.

[0054] Aromatic Mannich base curing agents are compounds that can be produced by reacting an aldehyde (usually formaldehyde), an amine, and a phenolic compound. The phenolic compound is of the kind that contains an aromatic ring having at least one directly bonded hydroxyl (-OH) substituent. It can have a single aromatic ring, such as phenol, cresol, or resorcinol. Alternatively, it can have more than one ring, for example, bicyclic compounds such as naphthol or biphenol. It typically contains a single aromatic ring.

[0055] At least one amine for forming the Mannich base curing agent (or at least one of the Mannich base curing agents) contains at least one aromatic ring, such as meta-xylenediamine (MXDA). Thus, the aromatic Mannich base curing agent or at least one of the Mannich base curing agents contains at least two aromatic rings, for example, at least one derived from the phenolic compound and at least one derived from the amine.

[0056] The coating composition can contain more than one aromatic Mannich base curing agent containing at least one NH group. Aromatic Mannich base curing agents can include those having at least one aromatic or aliphatic ring. They can include those in which the amine can be derived from a polyamine, such as 1,4-bis(aminomethyl)benzene, 1,3-bis(aminomethyl)benzene, 1,3-bis(aminomethyl)cyclohexane, ethylenediamine (EDA), diethylenetriamine (DETA), or triethylenetetramine (TETA)).

[0057] Although other amines can be present in the coating composition (such as acyclic aliphatic amines or aromatic amines that are not Mannich bases), the proportion of cycloaliphatic amines and aromatic Mannich bases accounts for 70 wt% or more of the total amount of curing agents.

[0058] Although an amine adduct curing agent (such as an adduct between an amine and an epoxide) can be present, in an embodiment, no curing agent is an adduct.

[0059] The cycloaliphatic amines and aromatic Mannich base curing agents can be present in the coating composition in an amount (total) in the range of 2 - 35 wt%, such as 5 - 30 wt% or 7 - 25 wt%. In an embodiment, the total amount of curing agents other than cycloaliphatic amines and aromatic Mannich base curing agents in the overall coating composition is less than 5.0 wt%, for example, 4.9 wt% or less.

[0060] The weight ratio of the aromatic Mannich base curing agent to the cycloaliphatic amine is at least 0.01:1.00 and is also 1.70:1.00 or less. In an embodiment, the weight ratio is at least 0.10:1.00. In an embodiment, the weight ratio does not exceed 1.50:1.00, for example, does not exceed 1.10:1.00. Thus, in an embodiment, the weight ratio is in the range of 0.10:1.00 - 1.10:1.00 or 0.15:1.00 - 1.00:1.00.

[0061] In one embodiment of the present invention, the total amount of amine curing agent present in the coating composition should be such that the molar ratio of active hydrogen to epoxy groups (sometimes referred to as the equivalent ratio) in the coating composition is in the range of 0.50:1.00 - 2.00:1.00, such as 0.60:1.00 - 1.85:1.00 or 0.70:1.00 - 1.35:1.00. This ratio of active hydrogen to epoxy groups enables effective curing of the coating composition of the present invention. The term active hydrogen corresponds to N-H hydrogen, i.e., where the hydrogen is directly bonded to the nitrogen atom of the amine group. These are typically present in curing agents (such as alicyclic amines and aromatic Mannich base curing agents) and sometimes also in crosslinking agents. It should be noted that a primary amine group (i.e., -NH 2 group) is considered to contain 2 active hydrogens.

[0062] In an embodiment, the weight ratio of the epoxy group-containing compound to the compound containing a primary or secondary amine group is 2.4:1.0 or less, such as 2.2:1.0 or less. In an embodiment, the weight ratio is 0.6 or greater, 1.0 or greater, or 1.5 or greater. Example ranges include 0.6:1.0 - 2.4:1.0, 0.6:1.0 - 2.2:1.0, 1.0:1.0 - 2.4:1.0, 1.0:1.0 - 2.2:1.0, 1.5:1.0 - 2.4:1.0, and 1.5:1.0 - 2.2:1.0.

[0063] [Organic boron compound]

[0064] In an embodiment, the coating composition used in the present invention may contain an organic boron compound of the formula BR a 3-n (OR a ) n , where n is 1, 2, or 3, and each R a is independently selected from H, C 1-12 alkyl, phenyl, and phenyl substituted with one or more (e.g., 1 - 4) C 1-6 alkyl, provided that at least one R a is not H. The alkyl can be cyclic or acyclic, or can contain cyclic and acyclic moieties. The acyclic alkyl or substituent can be linear or branched.

[0065] Each R a can optionally be substituted with one or more substituents selected from halogen, -OR t and -NR t 2 . Each R t is independently selected from H, C 1-6 alkyl, and C 1-6 haloalkyl. In an embodiment, Rt Selected from H and C 1-4 Alkyl group.

[0066] In one embodiment, each R a is independently selected from C 1 -C 8 alkyl group, such as C 2 -C 5 alkyl group. In other embodiments, n is 2 or 3. In an embodiment, no R a group has an optional substituent.

[0067] In other embodiments, the organoboron compound may have the formula R a B(O 2 R z ), where O 2 R z is a cyclic structural moiety in which two oxygens are covalently bonded to a boron atom, and R z is a divalent group covalently bonded to two oxygen atoms. R z can be an optionally substituted aliphatic hydrocarbon group having 1 to 12 carbon atoms, which is an acyclic alkyl group in an embodiment. The optional substituents are selected from those defined above for R a . In an embodiment, R z has 2 to 6 carbon atoms.

[0068] Examples of suitable organoboron compounds include triethyl borate, trimethyl borate, triisopropyl borate, tributyl borate, diethyl phenylborate, and diethyl methylborate.

[0069] The presence of the organoboron compound can improve the chemical resistance of the coating composition. 'Chemical resistance' refers to the tendency of the coating composition to absorb and subsequently desorb chemicals, solvents, or other liquid goods while maintaining film integrity.

[0070] OR a The amount of the group in the organoboron compound provided to the coating composition can be equal to or less than (on a molar basis) the amount of 1,2 - aminoalcohol groups formed by the reaction between the epoxy groups and the amine in the curing agent present in the composition.

[0071] In an embodiment, the amount of the organoboron compound in the coating composition ranges from 0 to 15 wt% based on the entire coating composition, such as in the range of 0 to 10 wt% or 0 to 5 wt%. In an embodiment, when used, the amount is at least 0.1 wt%, such as at least 0.5 wt%.

[0072] [Crosslinking agent]

[0073] The composition optionally comprises one or more crosslinking agents that can promote the crosslinking of the one or more base resins and other reactive components. They can be included in the base component, the curing component, or both.

[0074] Crosslinking agents generally contain at least two structural moieties that can participate in crosslinking reactions. They are typically classified separately from reactive diluents (see below) because they do not tend to form a polymer matrix on their own when subjected to typical curing conditions.

[0075] In embodiments, the crosslinking agent can be selected from those of the formula Si(R c ) 4-h (OR a ) h wherein R a is as defined above and h is an integer in the range of 1 - 4.

[0076] Each R c is independently selected from optionally substituted C 1-20 aliphatic hydrocarbon groups, optionally substituted C 6-12 aryl groups, and optionally substituted C 1-6 aryl groups having one or more C 1-6 hydrocarbon groups (such as C 6-12 alkyl). Optional substituents are selected from halogen, -OR t , -NR t 2 , -NCO, -C(O)OR t , -OC(O)R t , -C(O)NR t 2 , -OC(O)NR t 2 , -NR t C(O)NR t 2 and -OC(O)OR t . Additional optional substituents include those selected from -([CR t 2 j E-) p R t , -E-([CR t 2 j E-) p R t and -(CR t 2 ) j [O(CR t 2 ) k m [CR t / O\CR​​​t 2 polyethers, polyamines, polyether / amines and epoxy group-containing groups, wherein [CR t / O\CR t 2 represents an epoxy structural moiety.

[0077] R t is as defined above. Each E is independently selected from O and NR t . In an embodiment, all Es are O or all Es are NR t .

[0078] j is from 1 to 6, k is from 1 to 3, m is from 0 to 3 and p is from 1 to 30.

[0079] When h is less than 4, at least one R c is or contains an unsaturated aliphatic hydrocarbon group or contains a substituent as described above. In an embodiment, the silane structural moiety does not contain a halogen or a halogen-containing substituent.

[0080] More than one crosslinking agent may be present, but preferably at least one crosslinking agent has an h value of at least 2.

[0081] In an embodiment, the aliphatic hydrocarbon group and / or substituent in R c is saturated (i.e., an alkyl group) and at least one R c contains one or more additional substituents.

[0082] In an embodiment, the crosslinking agent of the formula Si(R c ) 4-h (OR a ) h may be in a partially hydrolyzed or condensed form, such as in the form of a dimer or oligomer in which two or more silicon atoms are bonded via Si-O-Si bonds. In an embodiment, the partially hydrolyzed or condensed form contains 2 to 20 silicon atoms.

[0083] In an embodiment, at least one R c group is selected from C 1-6 alkyl, phenyl and C 1-6 alkyl-substituted phenyl, optionally containing one or more substituents as defined above.

[0084] In an embodiment, all R a groups are selected from H and C 1-4 alkyl. In other embodiments, each R c group is selected from H and substituted C 1-4 alkyl. In other embodiments, the crosslinking agent may have the formula Si(OR a ) 4 and each R aSelected from H and C 1-4 alkyl group

[0085] In an embodiment, the crosslinking agent comprises a C 1-4 alkyl group substituted with an amine-containing substituent or an epoxy-containing substituent c group R. In an embodiment, at least one R c comprises an epoxy-containing substituent. When h is less than 3, the other R c groups are selected from unsubstituted C 1-20 aliphatic hydrocarbon groups, such as C 1-6 alkyl groups

[0086] When R c contains an amine substituent, it can have the formula -(CR m 2 ) j [NR m (CR m 2 ) k m NR m 2 , wherein each R m is independently selected from H and C 1-4 alkyl groups, j is 1 - 6, such as 2 - 4, k is 1 - 3, such as 2 - 3, and m is 0 - 3, such as 0 - 2. In an embodiment, all R m are selected from H and C 1-2 alkyl groups, and in other embodiments, only one R m group is not H

[0087] When R c contains an epoxy group, it can have the formula -(CR m 2 ) j [O(CR m 2 ) k n [CR m / O\CR m 2 , where R m is as defined above. In an embodiment, all R m are selected from H and C 1-2 alkyl groups, and in other embodiments, only one R m group is not H. j is 1 - 6, such as 2 - 4, k is 1 - 3, such as 1 - 2, and n is 1 - 3, such as 1 - 2

[0088] ​​Examples of crosslinking agents include 3-aminopropyltriethoxysilane, N-[3-(trimethoxysilyl)propyl]ethylenediamine, (N,N-diethylaminomethyl)triethoxysilane, glycidoxypropyltriethoxysilane, glycidoxypropyltrimethoxysilane, and tetraethoxysilane (TEOS) and partially hydrolyzed forms thereof.

[0089] In an embodiment, the crosslinking agent is an alkyl silicate or a condensate of an alkyl silicate, such as an alkyl C 1-6 alkyl ester, such as tetraethyl orthosilicate (TEOS). The condensate can be dimeric or oligomeric, for example, containing 2-20 silicon atoms connected via Si-O-Si bonds.

[0090] Other examples of crosslinking agents include organic carbonates, such as the organic carbonate of the formula O═C(OH) 2-z (OR a ) z where z is 1 or 2 and R a is as defined above. In an embodiment, z is 2. In an embodiment, each R a is an alkyl group. In other embodiments, the organic carbonate is a dialkyl carbonate, such as an alkyl C 1-6 dialkyl carbonate, such as dimethyl carbonate or diethyl carbonate.

[0091] In an embodiment, the total content of the crosslinking agent in the coating composition ranges from 0.1-30 wt% based on the entire coating composition, for example, in the range of 0.5-25 wt% or 1-20 wt%.

[0092] [Reactive diluent]

[0093] The coating composition may optionally contain one or more reactive diluents that are typically liquid at room temperature and pressure (i.e., 25 °C and 1.013 absolute bar) and are generally less viscous than epoxy resins. They can be included in the coating composition as part of the binder component.

[0094] Reactive diluents act like solvents in reducing the viscosity of the composition but do not contribute to its solvent or VOC content because they have reactive groups that allow them to combine with the coating resin or undergo chemical reactions independent of the main curing reaction. They generally have a lower viscosity than other binder components. Although they are capable of forming a polymer matrix upon undergoing curing conditions, the resulting film is usually not mechanically robust enough in the absence of the binder resin.

[0095] In an embodiment, the reactive diluent can be selected from aliphatic epoxy-containing compounds or epoxy-containing compounds containing no more than one aromatic or heteroaromatic group. Specific examples of reactive diluents include phenyl glycidyl ether, C 1-30Alkyl phenyl glycidyl ethers (such as C 1-12 or C 1-5 alkyl phenyl glycidyl ethers, such as methyl phenyl glycidyl ether, ethyl phenyl glycidyl ether, propyl phenyl glycidyl ether, and p-tert-butyl phenyl glycidyl ether) and glycidyl esters of carboxylic acids (such as glycidyl esters of fatty acids or branched alkane carboxylic acids such as pivalic acid or neodecanoic acid).

[0096] Other examples include glycidyl ethers of aliphatic alcohols having at least 2 hydroxyl groups (sometimes collectively referred to as aliphatic polyols). The aliphatic structural moiety derived from the aliphatic polyol may contain 1-16 carbon atoms. Examples include hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, glycerol triglycidyl ether, pentaerythritol tetraglycidyl ether, dipentaerythritol polyglycidyl ether, butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and sorbitol glycidyl ether.

[0097] The reactive diluent can also be prepared by epoxidizing unsaturated fats and oils, such as unsaturated fatty acids, glycerol diesters or triglycerides having C 4-30 fatty acid or fatty acid ester groups. An example is Cardolite TM NC-513, which is prepared by reacting epichlorohydrin with an oil obtained from cashew nutshells.

[0098] The reactive diluent can also be selected from epoxidized olefins, including dienes and polybutadienes. They can be C 2-30 -, C 6-28 -, C 6-18 -, C 14-16 - or C 6-12 epoxidized olefins. They can contain 1-4 epoxy groups, such as 1 or 2 epoxy groups, such as 2 epoxy groups. Specific examples include diepoxyoxtane and epoxidized polybutadiene. Epoxidized polybutadienes such as polybutadiene can have a molecular weight in the range of 500-100000, for example in the range of 1000-50000 or 2000-20000.

[0099] In an embodiment, the reactive diluent is present in the first part (A) of the two-component coating composition, i.e., together with the curable epoxy base.

[0100] In the overall coating composition, the reactive diluent may be present in an amount of 0.0 - 15.0 wt%, such as 1.0 - 15.0 wt%, 0.0 - 12.0 wt% or 2.0 - 12.0 wt%. These amounts can help reduce the viscosity of the coating composition, which is beneficial for high-solids and low-solvent compositions. However, in other embodiments, no reactive diluent is used and it is present in an amount of 5.0 wt% or less, or 3.0 wt% or less.

[0101] In an embodiment, the reactive diluent has a viscosity of less than 50 cP at 23 °C and 50% RH, such as less than 30 cP, or less than 20 cP. The viscosity can be measured using the cone-plate method described in ASTM D4287.

[0102] [Catalyst / Promoter]

[0103] One or more catalysts (or promoters) can be used to accelerate the curing agent. Examples include alcohols, phenols, carboxylic acids, sulfonic acids and salts.

[0104] The alcohols can be selected from C 1-8 aliphatic compounds having one or more hydroxyl groups, such as 1 - 6 hydroxyl groups. Examples include ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, benzyl alcohol, furfuryl alcohol, propylene glycol, butylene glycol, glycerol and sorbitol. The hydroxyl group can be the only functional group. Alternatively, other functional groups such as amino groups can also be present. For example, the alcohol can be a C 1-8 aliphatic amino alcohol, such as β-hydroxy tertiary amine, examples of which include triethanolamine, triisopropanolamine and dimethylaminoethanol.

[0105] Examples of phenols include aromatic compounds containing at least one hydroxyl group directly bonded to an aromatic ring. One or more fused or unfused aromatic rings (e.g., 1 - 3 aromatic rings) can be present in the molecule. Examples include phenol, dihydric phenols and trihydric phenols, biphenols, bisphenols and alcohols with fused aromatic rings, the latter such as those containing 2 or 3 fused aromatic rings. They can be substituted with one or more selected from halogen (usually chlorine), amino (e.g., C 1-10 alkylamino or C 1-10 dialkylamino), nitro, cyano, C 1-20 alkyl, C 1-20 alkenyl and C 1-20Substituted by substituents of alkoxy groups. Specific examples include 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, 2,4,6-trinitrophenol, 4-cyanophenol, 2,4,6-tris(dimethylaminomethyl)phenol, o-cresol, m-cresol, p-cresol, 4-ethylphenol, 4-isopropylphenol, 2,4-dimethylphenol, 3,5-dimethylphenol, nonylphenol, eugenol, isoeugenol, cardanol, 2,2'-dihydroxybiphenyl, 2,4'-dihydroxybiphenyl, 4,4'-dihydroxybiphenol, bisphenol A, bisphenol F, catechol, 4-tert-butylcatechol, resorcinol, 4-hexylresorcinol, orcinol, hydroquinone, naphthalenediol, anthracenediol, biphenyldiol, phloroglucinol, 2,3',4,5',6-pentahydroxybiphenyl, calixarene, and poly(4-vinylphenol).

[0106] Carboxylic acids include those containing one or more carboxyl groups (-COOH), for example, C-containing carboxylic acids with 1 to 3 carboxyl groups 1-12 alkyl and C 5-12 aryl. They may contain one or more substituents selected from halogen (usually chlorine), hydroxyl, C 1-10 alkoxy, and nitro. Examples include C 2-10 aliphatic acids and diacids such as acetic acid, propionic acid, butyric acid, lactic acid, malonic acid, oxalic acid, maleic acid, fumaric acid, and monoesters of diacids and C 6-10 aryl acids such as phenylacetic acid, benzoic acid, 4-tert-butylbenzoic acid, salicylic acid, 3,5-dichlorosalicylic acid, and 4-nitrobenzoic acid.

[0107] Sulfonic acids include C 1-12 alkyl and C 5-16 aryl sulfonic acids such as methanesulfonic acid, p-toluenesulfonic acid, 4-dodecylbenzenesulfonic acid, naphthalenedisulfonic acid, and dinonylnaphthalenedisulfonic acid.

[0108] Salts include nitrates, sulfates, thiocyanates, naphthenates, tetrafluoroborates, trifluoromethanesulfonates, halides, chlorates, bromates, iodates, perchlorates, perbromates, and periodates. The cations can be metals or non-metals. Metals include alkali metals (e.g., Li, Na, and K), alkaline earth metals (e.g., Mg and Ca), lanthanide metals (e.g., ytterbium), and Group 12 metals (e.g., zinc). Organic ions include quaternary ammonium ions and heterocycles having a charged nitrogen atom in the ring (e.g., imidazoline ). Specific examples include calcium nitrate, calcium naphthenate, ammonium thiocyanate, sodium thiocyanate, potassium thiocyanate, imidazoline thiocyanate, lithium tetrafluoroborate, lithium bromide, lithium trifluoroacetate, calcium chloride, ytterbium trifluoromethanesulfonate, lithium perchlorate, zinc trifluoromethanesulfonate, and lithium nitrate.

[0109] Other examples of accelerators include tertiary amines (e.g., 1,8-diazabicyclo[5.4.0]undec-7-ene, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylethanolamine, and tris(dimethylaminomethyl)phenol); and imidazoles (e.g., 1-methylimidazole, 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-ethyl-4-methylimidazole, 2-heptadecylimidazole, and diazabicyclooctane).

[0110] The accelerator is suitably used in an amount of 0.1 - 5 wt%, e.g., 0.1 - 3 wt%, based on the coating composition.

[0111] In a two-component coating composition, the catalyst / accelerator is typically included in the part containing the curing agent.

[0112] [Organic solvents]

[0113] One or more organic solvents may be present in the coating composition. These are generally organic liquids having a vapor pressure greater than 0.01 kPa at 25 °C or a boiling point less than 250 °C at 1 atmospheric pressure (101.3 kPa). They do not react with the binder or the curing component under the curing / drying conditions and ultimately evaporate and are lost from the coating film once fully cured / dried.

[0114] The solvent content includes the solvents added to the coating formulation but does not include any volatile compounds generated during the curing process (e.g., alcohols formed by hydrolysis of alkoxide moieties on any component of the coating composition).

[0115] When organic solvents are present, they may be selected from hydrocarbon compounds and heteroatom-containing organic compounds, where the heteroatoms are selected from O, S, and N, e.g., O.

[0116] Examples of organic solvents include alkyl aromatic hydrocarbons (such as xylene, toluene, and mesitylene), aliphatic hydrocarbons (such as cyclic and acyclic hydrocarbons selected from C 4-20 alkanes or mixtures of any two or more thereof), alcohols (such as benzyl alcohol, octylphenol, resorcinol, n-butanol, isobutanol, and isopropanol), ethers (such as methoxypropanol), ketones (such as methyl ethyl ketone, methyl isobutyl ketone, and methyl isopentyl ketone), and esters (such as butyl acetate). In an embodiment, the organic solvent contains 2 - 20 carbon atoms, e.g., 3 - 15 carbon atoms. Mixtures of any two or more organic solvents may be used.

[0117] When using organic solvents, the amount thereof can altogether account for at most 20% by weight of the whole coating composition, for example at most 10% by weight or at most 5% by weight. In an embodiment, it is in the range of 0.1 - 20% by weight, 0.1 - 20% by weight or 0.1 - 5% by weight. In other embodiments, the amount of the organic solvent in the coating composition is 1% by weight or less.

[0118] The content of the organic solvent is separate from the water content. This coating composition is generally a non-aqueous composition. Although water may be present, it is generally at a low concentration. If present, it is generally at a concentration of 5% by weight or less, for example 1% by weight or less, such as 0.5% by weight or less, based on the whole coating composition.

[0119] Some solvents can have other functions. For example, certain alcohols and phenols can also be used as catalysts / promoters. Therefore, the total amount of the solvent also includes those used as catalysts / promoters. In addition, the total amount of the catalysts / promoters also includes those that also serve as organic solvents.

[0120] [Other components]

[0121] In one embodiment, the coating composition of the present invention comprises one or more pigments and / or fillers. These can include titanium dioxide, iron oxide yellow and iron oxide red, phthalocyanine pigments, micaceous iron oxide, crystalline silica, wollastonite, barite, talc, feldspar, and calcium carbonate.

[0122] The composition can contain one or more other ingredients, such as those selected from thickeners or thixotropic agents (such as fine particle silica, bentonite, hydrogenated castor oil or polyamide wax), plasticizers, pigments, pigment dispersants, preservatives, stabilizers, flow aids, wetting agents, defoamers, reinforcing agents (such as fibers, graphene, and graphite), and adhesion promoters.

[0123] [Curing conditions]

[0124] The coating composition is generally provided as a two-component coating composition, wherein the first component contains an epoxy resin and the second component contains a curing agent.

[0125] The coating composition can be cured at a temperature in the range of -20°C to 50°C, and has surprisingly good curing times at temperatures in the range of -20°C to 25°C, for example -15°C to 15°C, -10°C to 15°C, -15°C to 0°C or -10°C to -1°C.

[0126] The application of the coating can be carried out at a relative humidity in the range of 0 - 100%, generally in the range of 20 - 80%, for example in the range of 40 - 60%. When the surface to be coated is relatively enclosed, such as the inner surface of a storage tank, the relative humidity during the coating operation can be controlled to reduce or avoid coating defects.

[0127] The second curing step can be optionally carried out, for example when the coating is in contact with highly corrosive chemicals. In this second step, sometimes referred to as a post-curing step, the coating is heated to a temperature of 50 °C or higher for a given period of time, for example in the range of 1 - 24 hours, such as 3 - 16 hours. Post-curing can generally be carried out at a temperature of at least 50 °C, for example in the range of 50 - 150 °C. In one embodiment, post-curing is carried out at a temperature in the range of 50 - 100 °C, such as 50 - 80 °C. In another embodiment, post-curing is carried out at a temperature in the range of 100 - 150 °C.

[0128] How post-curing is carried out depends on the nature of the surface to be coated and is obvious to a person skilled in the art. For example, curing can be carried out by heating the surface with hot air or hot water, for example by spraying. When the surface is the inner surface of a storage tank, heating can also be carried out by bringing the coated surface into contact with hot goods, using the heat from the goods for additional curing. Alternatively, the tank can be filled with hot water.

[0129] In one embodiment, post-curing is carried out by heating the surface with hot air or bringing the coated surface into contact with hot goods.

[0130] The curing / drying characteristics of the coating composition exhibit a good balance of drying characteristics, especially at lower temperatures. For example, the gel time is long enough so that the coating does not start to harden too quickly, which allows the operator sufficient time to apply the coating and correct any defects. However, the total drying time is short enough so that the coating application process is not unduly delayed.

[0131] The drying performance of the coating can be evaluated by various means. Examples include measuring the "tack-free" time (where the surface of the film has dried or cured enough to avoid sticking to a light object), the "hard-dry" time (where the film has cured sufficiently so that it no longer flows or sticks to a finger contacting it with a stronger force), or the "fully dry" or "through-dry" time (corresponding to the film being completely cured so that a large torsional force will not deform the film).

[0132] These times can be measured by methods such as those described in ASTM D5895 or ISO 9117-1.

[0133] In an embodiment, when measured at 5 °C, the through-dry time of the coating composition can be 38 hours or less, for example in the range of 10 - 38 hours, such as 15 - 30 hours. These can be measured by ISO 9117-1.

[0134] Additionally or alternatively, in an embodiment, the through-dry time at 0 °C can be 40 hours or less, for example in the range of 10 - 40 hours, such as 15 - 35 hours.

[0135] Additionally or alternatively, in embodiments, the dry-to-touch time at -7 °C can be 60 hours or less, such as in the range of 20 - 60 hours, such as 30 - 55 hours.

[0136] In embodiments, the touch-dry time at 5 °C is 14.0 hours or less and the hard-dry time is 17.5 hours or less. For example, the touch-dry time can be in the range of 5.0 - 14.0 hours and the hard-dry time can be in the range of 8.0 - 17.5 hours. In other embodiments, the touch-dry time can be in the range of 7.7 - 13.5 hours and the hard-dry time can be in the range of 9.8 - 16.0 hours. The touch-dry and hard-dry times can be measured by ASTM D5895.

[0137] [Coating Application]

[0138] The coating composition can be applied to the surface to be coated by methods known in the art. Examples of suitable methods include roll coating, spraying, and brushing. Spraying is preferably used because it results in an effective deposition of a uniform coating. A feature of the present invention is that the coating composition can be formulated to have a sprayable viscosity without the use of a significant amount of solvent. The composition can be applied by single-feed (or single-leg) airless spraying techniques or via multi-component application techniques.

[0139] It is generally considered that a coating composition having a viscosity of 10.0 poise or less, such as 8.0 poise or less, at 25 °C is optimal for single-leg airless spraying application. The viscosity is also generally at least 2.0 poise, such as at least 4.0 poise, at 25 °C. When the coating is a two (or more) component composition, the viscosity is measured for the freshly mixed composition, such as within 5 minutes of mixing the different components together. Method ASTM D4287 can be used to determine the viscosity of the coating composition. Higher viscosities tend to reduce the film quality, such as increasing the degree of unevenness and pinholes and making spraying more difficult and energy-consuming. Lower viscosities tend to increase the chance of overspray and splashing and may also reduce the sag resistance of the film, thus reducing the maximum achievable film thickness.

[0140] Each applied coating can have a thickness (i.e., dry film thickness) of 50 - 1000 microns, such as 150 - 900 microns or 300 - 800 microns after curing.

[0141] These compositions are particularly suitable as protective linings for reservoirs, containers, or associated pipes for the production, storage, or transportation of liquid or gaseous bulk chemicals including water. They are commonly used in the shipping or marine industry, oil and gas industry, chemical processing industry, energy industry, waste and water industry, transportation industry, and mining and metal industry.

[0142] The surface to be coated is usually metallic and can include both the inner and outer surfaces of storage tanks, reservoirs, and associated piping, flue ducts, and containment areas. In addition to liquid or gaseous chemicals, such surfaces can be exposed to high temperatures, whether static or cyclic, and also to high pressures, whether static or cyclic.

[0143] These compositions combine low uptake of a wide variety of chemicals and good washability, resulting in the coating composition being able to withstand cyclic loading with various types of liquids.

[0144] The coating composition can be applied directly to the surface as a primer / topcoat, i.e., the composition can be used as the only type of protective coating on the surface.

[0145] The coating composition of the present invention can also be applied as a primer, i.e., first applying the coating of the present invention on the surface to form a first coat, curing the coat, applying another coating on the first coat to form a second coat and curing the second coat. Application of other coats is also possible to provide three or more layers of the coating composition of the present invention. Usually no more than three layers are required, and the exact number of layers depends on the thickness of the individual layers. If a post-curing step is carried out, this is preferably done after all the layers have been deposited.

[0146] In an embodiment, only a single coat needs to be applied because it can provide a coating film with sufficient thickness without subsequent layers. Examples

[0147] The present invention will now be illustrated with reference to the following non-limiting examples.

[0148] The compositions of Comparative Examples 1-9 and Examples 1-4 were prepared according to the formulations described in Tables 1-3. They were prepared as two-part compositions using the same Part A provided in Table 1 and Part B with the formulations listed in Table 2. Concentrations are in weight % unless otherwise stated.

[0149] Curing agents:

[0150] (a) Alicyclic amine - Ancamine TM 2264, containing 45 - 55 wt% alicyclic polyamine and 45 - 55 wt% p-aminodicyclohexylmethane (PACM)

[0151] (b) Mannich base - Ancamine TM 2422, containing 60 - 70 wt% Mannich base derived from phenol, formaldehyde, and meta-xylenediamine (MXDA) and 30 - 40 wt% MXDA

[0152] (c) Alicyclic amine: 1,2-diaminocyclohexane

[0153] (d) Acyclic aliphatic amine - TETA (triethylenetetramine)

[0154] Crosslinking agent:

[0155] (a) Dynasylan TM GLYMO - (3 - glycidoxypropyltrimethoxysilane)

[0156] (b) Dynasylan TM AMEO - (3 - aminopropyltriethoxysilane)

[0157] Catalyst:

[0158] Huntsman Accelerator 2950CH TM — A mixture of 10 - 30 wt% 2,4,6 - tris(dimethylaminomethyl)phenol and 70 - 90 wt% Mannich base derived from phenol, formaldehyde and N,N - dimethyl - 1,3 - propanediamine.

[0159] Epoxy resin:

[0160] Bisphenol F epoxy resin (Epikote TM 862)

[0161] Pigments and fillers: selected from titanium dioxide, iron oxide, alkaline aluminosilicate, nepheline syenite and mica Other components: solvents, dispersants, thixotropic agents and texturing agents

[0162] The A - part and B - part compositions are prepared separately by blending the corresponding components together.

[0163] Table 1 - Formulation of the A - part for all examples

[0164] Material Quantity (wt%) Epoxy resin 24.9 Crosslinking agent (a) 14.5 Pigments and fillers 51.6 Others 9.0 <![CDATA[Solid content [1] > 99.2

[0165] [1] Proportion of non - volatile materials (wt%)

[0166] Table 2 - Formulation of the B - part

[0167]

[0168]

[0169] [1] This provides 11.9 - 15.3 wt% aromatic Mannich base and 1.7 - 5.1 wt% tertiary amine

[0170] Table 3 - Coating composition

[0171]

[0172] [1] A - part / B - part weight ratio

[0173] [2] Weight of Mannich base (MB) per unit weight of cycloaliphatic amine (CA)

[0174] [3] Ancamine based on the specified presence of 30 - 40 wt% metaphenylene di(methylamine) TM The 2422 Safety Data Sheet provides a range as well as for Huntsman Accelerator 2950CH TM Specified range

[0175] [4] Proportion (wt%) of curing agents other than cycloaliphatic amine and aromatic Mannich base curing agents, based on the total weight of curing agents

[0176] [5] Concentration (wt%) of curing agents other than cycloaliphatic amine and aromatic Mannich base curing agents, based on the overall coating composition

[0177] [6] The 1° + 2° amine compound refers to a compound containing primary and secondary amine groups

[0178] [7] Active (N - H) hydrogen / epoxy group molar ratio in the coating composition

[0179] Tests were conducted to measure the dry - time performance at various temperatures in addition to gel time, viscosity, and chemical resistance to various liquids

[0180] [Test 1 - Dry - through time]

[0181] The dry - through time was determined using a baseplate and plunger assembly by the method detailed in ISO9117 - 1, where the plunger has a rubber tip, is covered with nylon gauze, and has a mass of 1.5 kg. The base component (Part A) and the curing component (Part B) were separately prepared by mixing the constituent components. Then the components of Part A and Part B were mixed together and applied to a glass sample plate with a wet - film thickness of 600 μm using a drawdown bar. Then they were placed in an environmental chamber at the temperature specified in Table 3 and checked hourly until the sample was touch - dry. Then the sample was evaluated by placing the plunger on the surface of the dry coating film for 10 s, then rotating the plunger 90° and removing it from the surface. If an imprint on the coating was observed, the sample was returned to the environmental chamber for an additional 30 minutes and then tested again in the same manner. This step was repeated until no imprint was observed. The dry - through time was recorded as the first interval when no imprint was left on the coating. The results are shown in Table 3

[0182] Table 4 - Dry - through time at different temperatures

[0183]

[0184] [1] No result - The dry state was not observed below 5 °C.

[0185] This test shows that Examples 2 and 3 have excellent (faster) dry - through times at low temperatures.

[0186] [Test 2 - Surface dry and hard dry times]

[0187] These are representative determinations by the method of ASTM D5895. The base (Part A) and curing (Part B) components are prepared separately and after being mixed together, they are applied to a 30 - cm long glass sample with a wet film thickness of 600 μm by a cube applicator. Then they are placed on an automatic mechanical recorder operating at the temperatures specified in Table 5 in an environmental chamber. The floating needle on the recorder is applied to the surface of the wet film and gradually slid across and finally over the drying / curing film at a constant rate. Usually no imprint is seen in the initial stage because the coating composition flows back into the groove created by the needle. At a certain moment, the coating composition is hard enough to maintain the shape of the groove created by the needle. At another moment, the composition is hard enough so that the edges of the groove start to tear. The tearing point is noted as the surface dry time. At a later time point, the tearing stops and the coating is hard enough so that the needle moves up to the surface of the hardened coating. This time point is noted as the hard dry time.

[0188] Table 5 - Surface dry and hard dry times at 5 °C

[0189] Example Surface drying time (hours) Hard drying time (hours) Comparative example 2 11.0 19.0 Comparative example 3 4.6 7.8 Comparative example 4 7.5 9.5 Comparative example 5 6.7 8.3 Comparative example 7 6.8 12.0 Comparative example 8 8.5 15.0 Comparative example 9 2.0 6.0 Example 1 11.5 13.5 Example 4 8.0 10.5

[0190] These tests show that the coating compositions of the present invention have acceptable drying characteristics at low temperatures. In combination with the gel time results (see below), the coating compositions of the present invention have a good balance of drying characteristics, so that they do not gel too quickly and do not have an overly long drying / curing time.

[0191] [Test 3 - Gel time]

[0192] The gel time is measured using a Shyodu digital gel timer. The test is carried out inside an environmental chamber maintained at 25 °C. The components of Part A and Part B are prepared separately in an amount sufficient to form 200 ml of the coating composition. These two parts are added to a sample container and the timer is started at this time point. Then the sample is mixed using a stirrer and the rotating hook of the gel timer device is inserted into the coating composition. The gel time is automatically determined by the device based on the time when the composition becomes too viscous for the hook to rotate easily. The results are shown in Table 5.

[0193] The gel time is related to the pot life. A higher gel time / pot life is generally desired as it increases the application time of the coating (before drying) with less restriction. However, since the gel time is also related to the drying time, it should not be too high. As can be seen from Table 6, Examples 1 - 4 show the optimal gel time, which falls between the shorter and longer gel times of Comparative Examples 1 - 8. Although Comparative Example 9 has a reasonable gel time, it has a relatively very high viscosity (see Test 4), which makes it not suitable for airless spraying application, especially single - leg airless spraying application.

[0194] Table 6 - Gel Time

[0195] Example Gel time (minutes) Comparative example 1 150 Comparative example 2 199 Comparative example 3 61 Comparative example 4 69 Comparative example 5 49 Comparative example 6 79 Comparative example 7 64 Comparative example 8 67 Comparative example 9 116 Example 1 135 Example 2 118 Example 3 108 Example 4 92

[0196] [Test 4 - Viscosity]

[0197] The viscosity was measured using a cone - plate viscometer at a shear rate of 10000 s -1 by the methods of ASTM D4287 and ISO 2884 / 1. The A and B part components of the coating composition were prepared separately and pre - conditioned in an incubator at 25 °C before testing. Then they were mixed and tested immediately. The viscometer test was carried out using 0.2 ml of the coating composition at 25 °C. The results are shown in Table 6.

[0198] Table 7 - Viscosity (Poise)

[0199]

[0200]

[0201] This test shows that the coatings have a viscosity suitable for spraying application when mixed, except for Comparative Example 9 which has a high viscosity that makes airless spraying application difficult.

[0202] [Test 5 - Chemical Resistance]

[0203] The procedure used corresponded to ISO 2812 Part 1 Method A. The A and B parts of each composition were mixed and spray - applied (using airless spraying equipment) onto both sides of a 150 mm × 100 mm × 3 mm carbon steel test panel that had been pre - cleaned and grit - blasted according to ISO8501 Sa 2 1 / 2 and had a surface profile of > 75 μm. The samples were conditioned at 23 °C for 7 days and then immersed in various test liquids at a specified temperature for a period of 12 months. The samples were visually evaluated for defects at 1, 3, 6, and 12 - month intervals and then removed and tested for adhesion according to the pull - off test of ISO 4624.

[0204] Test Examples 2 and 3 and Comparative Examples 1 and 6. Examples 2 and 3 and Comparative Example 1 have 6-month chemical resistance properties against crude oil (up to 80 °C), distilled water (up to 98 °C), water / amine mixture (up to 80 °C), water / monoethylene glycol mixture (up to 95 °C), and acidic water at pH 2 (up to 90 °C). Comparative Example 6 achieved similar results for the distilled water test but failed in the crude oil, acidic water, water / monoethylene glycol mixture, and water / amine mixture tests.

[0205] Samples of Examples 2 and 3 and Comparative Example 1 were also subjected to an autoclave test according to NACE TM0185. All three examples gave 1-month protection in a 3 wt% NaCl aqueous solution at 150 °C.

[0206] Similarly, all three samples provided 1-month protection in the liquid phase of a gas mixture containing 95 wt% of crude oil and 5 wt% of a 3 wt% NaCl aqueous solution and pressurized to 17 bar and containing 10 vol% H 2 S, 10 vol% CO 2 and 80 vol% CH 4 at 150 °C.

[0207] These tests demonstrate that the samples of the present invention have effective protection properties against various different liquids.

Claims

1. A coating composition comprising a base component and a curing component, wherein the base component comprises an epoxy resin and the curing component comprises an alicyclic amine and an aromatic Mannich base curing agent, and the alicyclic amine and the aromatic Mannich base curing agent each have a primary amine group, a secondary amine group, or both. Wherein: The weight ratio of the aromatic Mannich base curing agent to the alicyclic amine curing agent is in the range of 0.01:1.00 - 1.70:1.00; The aromatic Mannich base curing agent is derived from an aldehyde, a phenolic compound, and an amine containing at least one aromatic ring; and The proportion of the alicyclic amine curing agent and the aromatic Mannich base curing agent is 70% by weight or more based on the total amount of the curing agent.

2. The coating composition according to claim 1, wherein the weight ratio of the aromatic Mannich base curing agent to the alicyclic amine curing agent is at least 0.10:1.00 and / or is 1.50:1.00 or less.

3. The coating composition according to claim 1 or 2, wherein the epoxy resin is a bisphenol F epoxy resin.

4. The coating composition according to any one of claims 1 - 3, wherein the alicyclic amine is an alicyclic polyamine and / or the aromatic Mannich base is derived from m - xylylenediamine (MXDA), formaldehyde, and phenol.

5. The coating composition according to any one of claims 1 - 4, which is suitable for application by single - leg airless spraying.

6. The coating composition according to any one of claims 1 - 5, which is a protective lining for the inner surface of a container for chemical storage or chemical transportation.

7. The coating composition according to any one of claims 1 - 6, Wherein: (i) The weight ratio of the epoxy - containing compound to the compound containing primary and / or secondary amine groups is 2.4: 1.0 or less; and / or (ii) The molar ratio of active (N - H) hydrogen / epoxy group in the coating composition is in the range of 0.50:1.00 - 2.00:1.

00.

8. The coating composition according to any one of claims 1 - 7, wherein one or more of the following conditions apply: (i) The dry - through time of the coating composition at 5 °C is 38 hours or less; (ii) The dry - through time of the coating composition at 0 °C is 40 hours or less; (iii) The dry - through time of the coating composition at - 7 °C is 60 hours or less; (iv) The surface - dry time at 5 °C is 14.0 hours or less and the hard - dry time is 17.5 hours or less; Wherein the dry - through time is determined by ISO9117 - 1, and the surface - dry and hard - dry times are determined by ASTM D5896.

9. The coating composition according to any one of claims 1 - 8, wherein the coating composition is a protective lining coating.

10. The coating composition according to any one of claims 1 - 9, comprising at least one organic boron compound.

11. The coating composition according to claim 10, wherein the concentration of the organic boron compound in the coating composition is in the range of 0.1 - 15% by weight.

12. A substrate coated with the coating composition according to any one of claims 1 - 11.

13. The substrate according to claim 12, wherein the substrate is the inner surface of a tank or reservoir for storing or transporting water or chemicals.

14. A method of coating a substrate, comprising applying a coating composition according to any one of claims 1-11 to the substrate and curing the coating composition.

15. The method according to claim 14, wherein the substrate is the inner surface of a reservoir for storing or transporting water or chemicals and / or the coating composition is cured at a temperature in the range of -15°C to 15°C.

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