Zinc-rich epoxy coating

Abstract

The present invention relates to a coating composition comprising: - a resin component comprising an epoxy resin and a petroleum resin; - at least 65 wt.-% of zinc particles based on the total solids weight of the coating composition; - a metal phosphorous salt; and - a curing agent. Furthermore, the present invention relates to a multi-part coating of the coating composition, a process for the preparation of the coating composition and a substrate coated with the coating composition.

Description

TECHNICAL FIELD

[0001] The present invention relates to a zinc-rich epoxy-based anticorrosive coating composition. More particularly, the present invention relates to an anticorrosive coating composition having improved corrosion resistance, fast drying and curing, and low density. BACKGROUND

[0002] Anticorrosive coatings are widely used in various industrial fields to protect the coated substrate from external corrosion, especially for protecting iron and steel structures, such as steel structural parts of industrial structures like bridges, refinery plants, petrochemical industrial production plants, power plant equipment, storage tanks, cranes, windmills, and civil buildings.

[0003] Such coatings can be based on several resin systems, such as silicate, epoxy, polyurethane, polysiloxane, alkyd, etc. Among them, epoxy-based anticorrosive coatings are widely used.

[0004] For example, CN111117418A proposes a two-component coating composition, wherein the A part comprises an epoxy resin, and the B part comprises b1) a polyether amine, b2) an aromatic ring-containing alkyl diamine, and b3) an epoxy resin.

[0005] In addition, it has also been found that some metals, such as zinc, can be added to the primer to help improve the anticorrosive properties of the coating. When the coating is in action, the metal, such as zinc, can act as a sacrificial anode material to protect the steel or iron substrate which becomes the cathode.

[0006] For example, CN104603213A proposes an anticorrosive zinc-containing primer composition, which comprises a silicate-based binder system, zinc particles, hollow glass microspheres, and conductive pigments. The patent hopes to improve the corrosion resistance in a cost-effective and limited amount of zinc added way.

[0007] In addition, CN106068310A also proposes a scheme of adding zinc particles in various binder systems. CN104745044A proposes a zinc-rich primer using an activation technology, in which zinc powder is added in the base resin.

[0008] However, the anticorrosive performance of ordinary epoxy coatings cannot meet the anticorrosive requirements in some special atmospheric environments, and although it can be improved by adding zinc, the traditional zinc-rich epoxy coating may lead to an increase in cost or may lead to a loss of comprehensive performance and processability due to the addition of a large amount of zinc powder. In addition, although it is possible to reduce the amount of zinc powder in the formula while meeting the zinc content in the dry film by adding hollow microspheres to the zinc-rich epoxy coating, the anticorrosive performance and drying performance need to be improved. SUMMARY

[0009] To solve the above and other problems existing in the prior art, in one aspect, the present application provides a coating composition comprising:

[0010] - a resin component comprising an epoxy resin and a petroleum resin;

[0011] - at least 65 wt.-% of zinc particles based on the total solids weight of the coating composition;

[0012] - a metal phosphorous salt; and

[0013] - a curing agent.

[0014] In another aspect, the present application provides a multi-part coating composition comprising at least two parts:

[0015] Part A comprising a resin component, zinc particles and a metal phosphorous salt, wherein the resin component comprises an epoxy resin and a petroleum resin, and the content of zinc particles is at least 65 wt.-% based on the total solids weight of the coating composition; and

[0016] Part B comprising a curing agent.

[0017] In yet another aspect, the present application provides a method for preparing a coating composition comprising providing at least a resin component, zinc particles, a metal phosphorous salt and a curing agent or Part A and Part B comprising these components, respectively, as described above, and subsequently mixing them.

[0018] Finally, the present application also provides a substrate, in particular a steel and iron structure, coated with the coating composition of the present application.

[0019] The coating composition of the present application provides improved adhesion to the substrate. At the same time, the coating composition of the present application also provides a balanced overall performance, including improved corrosion resistance and fast drying and curing, and the coating composition is low density. DETAILED DESCRIPTION

[0020] For purposes of the following detailed description, it is to be understood that the application can assume various alternative variations and step sequences, except where expressly specified to the contrary, and that the present application is not limited to specific embodiments described. In addition, it is to be understood that the use of terminology, such as "for example," "for instance," "as an example," "wherein," or "whereby," among others, are not intended to limit the scope of the claimed application but are instead used to elucidate

[0021] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the application are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0022] Also, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a range of "1 to 10" is to be understood to include any and all subranges between (and including) the minimum value of 1 and the maximum value of 10; that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10.

[0023] In this application, the use of the singular includes the plural and vice versa unless specifically stated otherwise. In addition, in this application, the use of "or" means "and / or" unless specifically stated otherwise. Furthermore, in this application, the use of "an" or "one" means "at least one" unless specifically stated otherwise. For example, "an epoxy," "a hydrocarbon resin," and / or "a diamine," and the like, means one or more of any of these things.

[0024] The coating composition of the present application can advantageously be formulated as a multi-part coating composition. In the case of a multi-part coating composition, the coating composition of the present application comprises Part A as the base component or base of the coating.

[0025] The resin component of the coating composition of the present application comprises an epoxy resin (sometimes also referred to herein as an epoxy compound). Suitable epoxy resins have more than one 1,2-epoxy group. They can be of the liquid type or of the solid type. Generally, the epoxy resins have an epoxy equivalent weight of 100 to about 2,000 g / eqv., typically about 150 to 500 g / eqv., for example about 170 to about 350 g / eqv., for example about 180 to about 300 g / eqv. Those skilled in the art will appreciate that the epoxy equivalent weight refers to the number of grams of epoxy resin containing one equivalent of epoxy group. Liquid type epoxy resins suitable for use in the present application have relatively high viscosity and relatively low epoxy equivalent weight. Liquid type epoxy resins for use in the present application have a viscosity of about 8,000 to about 16,000 cps, for example about 10,000 to 12,000 cps at 25°C. The viscosity is measured according to standard methods generally used in the art.

[0026] In addition, the epoxy resins can be saturated or unsaturated, cyclic or acyclic, aliphatic, alicyclic, aromatic, or heterocyclic. They can contain substituents such as halogen, hydroxyl, and ether groups.

[0027] Examples of epoxy resins can be polyepoxides having an average of more than one, typically about two, epoxy groups per molecule; i.e., 1,2-epoxy equivalent weight greater than one. Commonly used polyepoxides as epoxy resins are polyglycidyl ethers of cyclic polyols, for example, polyglycidyl ethers of polyhydric phenols such as bisphenol A, resorcinol, hydroquinone, benzene glycol, phloroglucinol, and catechol; or polyglycidyl ethers of polyols such as alicyclic polyols, especially cycloaliphatic polyols such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, 2,2-bis(4-hydroxycyclohexyl)propane, 1,1-bis(4-hydroxycyclohexyl)ethane, 2-methyl-1,1-bis(4-hydroxycyclohexyl)propane, 2,2-bis(4-hydroxy-3-tert-butylcyclohexyl)propane, 1,3-bis(hydroxymethyl)cyclohexane, and 1,2-bis(hydroxymethyl)cyclohexane. Examples of aliphatic polyols include, among others, trimethylpentanediol and neopentyl glycol.

[0028] In one preferred embodiment, the epoxy resins of the present application can include those such as diglycidyl ethers based on bisphenol A, bisphenol F, glycerol, novolac, and the like. Exemplary suitable polyepoxides are described in U.S. Patent No. 4,681,811, column 5, lines 33-58, the reference to which is incorporated herein by reference.

[0029] In another preferred embodiment, the epoxy resins of the present application include epoxy resins based on bisphenol A, bisphenol F, or mixtures thereof.

[0030] Commercially available examples of suitable epoxy resins include: Shell Epon 828 (bisphenol A-epichlorohydrin epoxy resin) and / or blends of this resin with difunctional epoxy reactive diluents such as neopentyl glycol diglycidyl ether, resorcinol diglycidyl ether and cyclohexane dimethanol diglycidyl ether; bisphenol A liquid epoxy resins such as NPEL-128E; bisphenol A solid epoxy resins such as YD-011X75; bisphenol F epoxy resins, i.e., Shell Epon DPL 862 (bisphenol F-epichlorohydrin epoxy resin); and epoxy novolac resins such as Epalloy 8250 (epoxy novolac resin) from CVC, Cherry Hill, N.J.; Araldite EPN 1139 from Ciba Geigy; and DEN 438 from Dow Chemical. These epoxy resins exhibit good chemical resistance. Suitable non-aromatic epoxy resins include diglycidyl ethers of hydrogenated cyclohexane dimethanol and hydrogenated bisphenol A epoxy resins such as: Epon 1510, Epon 4080E, Heloxy 107 and Epon 1513 (hydrogenated bisphenol A-epichlorohydrin epoxy resins) from Shell Chemical, Houston, Texas; Santolink LSE-120 from Monsanto, Springfield, Mass.; Epodil 757 (cyclohexane dimethanol diglycidyl ether) from Pacific Anchor, Allentown, Pa.; Araldite XUGY 358 and PY 327 from Ciba Geigy, Hawthorne, New York; Epirez 505 from Rhone-Poulene, Louisville, Ky.; Aroflint 393 and 607 from Reichold, Pensacola, Florida; and ERL 4221 from Union Carbide, Tarrytown, New York. Other suitable non-aromatic epoxy resins include DER 732 and DER 736.

[0031] In various embodiments of the present application, the amount of epoxy resin of the coating composition of the present application is about 3 to about 25 wt.%, preferably 5 to 20 wt.%, more preferably about 7 to 15 wt.%, based on the total weight of the coating composition. In a preferred embodiment of the present application, the coating composition can contain both a liquid type epoxy resin and a solid type epoxy resin as the epoxy resin component, preferably the liquid type epoxy resin and the solid type epoxy resin are selected from those epoxy resins as described above, more preferably bisphenol A or F type epoxy resins. In such embodiments, the amount of the liquid type epoxy resin can be about 0.5 to about 15 wt.%, preferably about 1 to about 10 wt.%, more preferably about 1 to about 7 wt.%. In these embodiments, the amount of the solid type epoxy resin can be about 1 to about 20 wt.%, preferably about 2 to about 15 wt.%, more preferably about 2 to about 12 wt.%.

[0032] In addition, a petroleum resin must also be included in the resin component of the coating composition of the present application. Petroleum resins are also known as hydrocarbon resins or HCRs. Petroleum resins are thermoplastic resins produced from the C5, C9 fractions of petroleum cracking by processes such as pretreatment, polymerization, distillation, etc. Generally, petroleum resins include aliphatic or cycloaliphatic resins based on C5 or cycloaliphatic dienes such as dicyclopentadiene, and aromatic components based on C9 such as vinyltoluene or indene or aromatic resins and mixtures thereof. In some cases, petroleum resins also include their hydrogenated products, i.e. hydrogenated petroleum resins such as C5 hydrogenated petroleum resins or C9 hydrogenated petroleum resins. Petroleum resins can also include modified petroleum resins, which are a low viscosity liquid resin with non-reactive hydroxyl groups in the aromatic hydrocarbon functional group compared to ordinary petroleum resins, and can be used in solvent-borne, solventless or high solid content epoxy systems. The petroleum resins and modified petroleum resins used in the embodiments of the present application can be commercially available.

[0033] In various embodiments of the present application, the amount of petroleum resin in the coating composition of the present application is about >0 (e.g. 0.5) to about 10 wt.%, preferably about 1 to about 8 wt.%, more preferably about 1.5 to 5 wt.%, based on the total weight of the coating composition.

[0034] Preferably, in the coating composition according to the present application, the weight ratio of the epoxy resin to the petroleum resin is in the range of 2-10: 1, preferably 3-8: 1, for example about 6: 1. The inventors have found that when the petroleum resin is added to the resin component containing the epoxy resin, especially mixed in the above-mentioned proportions, it is possible to result in a coating composition having significantly improved hydrophilic and hydrophobic water balance.

[0035] According to the present application, the coating composition should also include zinc particles. In particular, the content is at least 65 wt.-%, based on the total solids weight of the coating composition. As used herein, the term "particles" refers to materials in the form of particles, such as powders or dusts as well as flakes, and can be in the form of any shape, for example spherical, oval, cubic, rod-like, disc-like, prismatic, etc.

[0036] As used herein, the term "zinc" or "zinc particles" refers to metal particles in which zinc is the predominant component or in which the purity of zinc is very high in the individual particles. Suitable zinc particles have a purity of metal zinc of at least 94 %, preferably at least 96 % or at least 98 % or 99 %, based on the total weight of the particles, for example metal particles which are generally sold commercially in the form of zinc powder or zinc dust, and include metal particles having up to 100 % metal zinc. The remainder of the particles other than zinc can be other metal elements or compounds thereof, and these portions can be, for example, a coating of the particles or can also be an alloy material with zinc. Suitable zinc particles are zinc powder specifications as specified according to ASTM D520, type II or type III. Furthermore, particles of zinc alloys in which zinc is the predominant metal can also be used as zinc particles of the present application, provided that they contain at least 94 % metal zinc, based on the total weight of the zinc alloy. Accordingly, those alloys in which zinc is the predominant metal and which contain other metal elements in a significant amount, for example more than 6 %, for example zinc alloys containing more than 50 wt.-% and generally less than 94 %, for example 90 %, of zinc, are not within the scope of "zinc" or "zinc particles" of the present application.

[0037] The average particle size of the zinc particles can be at least 1 micron, such as at least 2 microns, such as at least 5 microns, such as at least 5.5 microns, such as at least 6 microns, and can be not more than 150 microns, such as not more than 30 microns, such as not more than 20 microns, such as not more than 10 microns, such as not more than 8 microns. The average particle size of the zinc particles can be from 1 to 150 microns, such as from 2 to 30 microns, such as from 5 to 20 microns, such as from 5.5 to 10 microns, such as from 6 to 8 microns. The particle size selected can depend on the viscosity and application performance of the intended coating. The average particle size reported herein is the average particle size provided by the zinc particle manufacturer and can be measured by various methods known in the art, such as laser diffraction, etc.

[0038] The coating composition can include at least 65 weight percent of zinc particles, such as at least 70 weight percent of zinc particles, such as at least 75 weight percent of zinc particles, such as at least 80 weight percent of zinc particles, such as at least 85 weight percent of zinc particles, based on the total solids weight of the coating composition, and can include no more than 95 weight percent of zinc particles, such as no more than 90 weight percent of zinc particles, such as no more than 85 weight percent of zinc particles. Although other metal particles, such as those zinc alloys having less than 94% zinc content or aluminum or aluminum alloy particles, etc. can also be contained in the coating composition of the present application, it is preferred that a minimal amount of other metal particles, such as no more than 5%, 4%, 3%, or 1% of the total solids weight of the coating composition, be included in the coating composition, more preferably that no other metal particles, including metallic elements of other metals (i.e. zero valence) and metal alloys, be included at all.

[0039] In addition, the zinc particles can also be surface treated to modify the surface of the zinc particles. The surface treated zinc particles can include a pre-treatment layer formed by exposing the zinc particles to a pre-treatment composition. As used herein, the term "pre-treatment composition" refers to a composition that, upon contact with a zinc material, reacts therewith and chemically alters the surface of the material and bonds therewith to form a protective layer. The pre-treatment composition used for surface modification of the zinc particles can include suitable known compositions used in the art for pre-treating zinc materials.

[0040] In addition, according to the present application, a phosphorus-containing salt of a metal must also be used in the coating composition. In the present application, the "phosphorus-containing salt" refers to an inorganic salt containing a phosphorus element in the anionic acid group, including phosphates, phosphites, hypophosphites, hydrogen phosphates, dihydrogen phosphates, hydrogen phosphites, dihydrogen phosphites, polyphosphates, or polyphosphates, etc., of which phosphates, polyphosphates, and hydrogen phosphates can be preferred. Modified forms, such as phosphosilicates, of these phosphorus-containing salts can also be used. Suitable metals for the cationic portion of the phosphorus-containing salt of a metal include zinc, aluminum, magnesium, calcium, strontium, zirconium, iron, barium, etc. However, it is preferred that the metal not include an alkali metal.

[0041] Thus, specific examples of suitable phosphorus-containing salts of a metal include zinc phosphate, aluminum tripolyphosphate, strontium aluminum polyphosphate, zirconium hydrogen phosphate, and phosphates or polyphosphates modified with silicon, such as silicates, such as zinc strontium calcium phosphosilicate. Preferably, the phosphorus-containing salt of a metal is a phosphate of a metal, more preferably zinc phosphate.

[0042] The inventors of the present application have found that the use of a metal-containing phosphate salt in a zinc-rich epoxy-based coating composition, in particular the use of a combination of zinc particles with a metal-containing phosphate salt, for example at least 65 wt.%, at least 70 wt.%, more preferably at least 75 wt.%, particularly preferably at least 80 wt.%, leads to better long-term corrosion protection. It has also been found that it is particularly advantageous to control the weight ratio of the metal-containing phosphate salt to the zinc particles in the range of 1 :20 to 1 :60, preferably 1 :25 to 1 :45, especially at zinc particle contents of more than 75 wt.%.

[0043] The coating composition of the present application further comprises a curing agent component. Suitable curing agent components for epoxy resins include, in particular, amine components. Amine components generally include any compound that can act as a source of nitrogen. According to embodiments of the present application, the amine component can include proteins, polypeptides, amino acids, organic amines, polyamines, ammonia, ammonium salts of monomeric polycarboxylic acids, ammonium salts of polymeric polycarboxylic acids, ammonium salts of inorganic acids, polyether amines, polyamides, adducts thereof with epoxy resins such as bisphenol A-type solid epoxy resins, and mixtures thereof, etc.

[0044] In some embodiments, suitable curing agents include, for example, polyamines. Non-limiting examples of polyamine curing agents include primary or secondary diamines or polyamines in which the groups attached to the nitrogen atoms can be saturated or unsaturated, aliphatic, alicyclic, aromatic, aromatic-substituted aliphatic, aliphatic-substituted aromatic, and heterocyclic. Non-limiting examples of suitable aliphatic and alicyclic diamines include 1,2-ethanediamine, 1,2- propanediamine, 1,8-octanediamine, isophorone diamine, propane-2,2-cyclohexylamine, and the like. Non-limiting examples of suitable aromatic polyamines include phenylenediamines and toluenediamines, such as m-xylylenediamine, o-phenylenediamine, and p-toluylenediamine. Polynuclear aromatic diamines such as 4,4'-diphenyl diamine, methylene dianiline, and monochloromethylene dianiline are also suitable.

[0045] Examples of suitable aliphatic diamines include, but are not limited to, ethylenediamine, 1,2-diaminopropane, 1,4-diaminobutane, 1,3-diaminopentane, 1,6-diaminohexane, 2-methyl-1,5-pentanediamine, 2,5-diamino-2,5-dimethylhexane, 2,2,4- and / or 2,4,4-trimethyl-1,6-diaminohexane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,3- and / or 1,4-cyclohexanediamine, 1-amino-3,3,5-trimethyl-5-aminomethyl- cyclohexane, 2,4- and / or 2,6-hexahydrotoluenediamine, 2,4'- and / or 4,4'-diamino- dicyclohexylmethane and 3,3'-dialkyl 4,4'-diamino-dicyclohexylmethane such as 3,3'- dimethyl-4,4'-diamino-dicyclohexylmethane and 3,3'-diethyl-4,4'-diamino- dicyclohexylmethane, 2,4- and / or 2,6-diaminotoluene and 2,4'- and / or 4,4'- diaminodiphenylmethane, or mixtures thereof. Cycloaliphatic diamines are commercially available from Huntsman Corporation (Houston, TX) under the trade name JEFFLINK, such as JEFFLINK 754. Additional aliphatic cyclic polyamines can also be used, such as DESMOPHEN NH 1520 available from Covestro AG and / or CLEARLINK 1000, which is a secondary aliphatic diamine available from Dorf Ketal. The reaction product of isophorone diamine and acrylonitrile, POLYCLEAR 136, available from BASF / Hansen Group LLC, is also suitable. Other exemplary suitable polyamines are described in U.S. Patent No. 4,046,729, column 6, line 61 to column 7, line 26, and U.S. Patent No. 3,799,854, column 3, lines 13-50, which are incorporated herein by reference. Other polyamines can also be used, such as the ANCAMINE polyamines available from Evonik Industries.

[0046] Suitable polyamides include any polyamide known in the art. Polyamides used as curing agents are typically products condensed from dimeric acids (or esters) with polyamines. For example, the ANCAMIDE polyamides available from Evonik Industries.

[0047] The curing agent can also include a polyetheramine. Polyetheramines are compounds having a polyether backbone and also containing amine groups as terminal reactive functional groups. Polyetheramines are obtained by aminolysis of polyethylene glycol, polypropylene glycol, or ethylene / propylene glycol copolymers at high temperature and pressure. By selecting different polyoxyalkyl structures, the reactivity, toughness, viscosity, and hydrophilicity of the polyetheramine can be adjusted, while the amine groups provide the polyetheramine with the ability to react with a variety of compounds. Polyetheramines that can be used in the present application include polyether monoamines, polyether diamines, polyether triamines, and the like. In particular, polyetheramines that can be used in the present application can include polyoxyethylene diamines, polyoxypropylene diamines, polyoxybutylene diamines, and polyoxyethylene triamines, polyoxypropylene triamines, polyoxybutylene triamines. Examples of commercially available polyetheramines that can be used in the present application can include, for example, the Jeffamine® series of products. Examples of such polyetheramines include aminated propoxylated pentaerythritol, such as Jeffamine XTJ-616, and those represented by the following formulas (IV) through (VI).

[0048] According to formula (IV), the amine-containing compound can include or be represented by:

[0049]

[0050] where y = 0-39, and x+z = 1-68.

[0051] Suitable amine-containing compounds represented by formula (IV) of the present application include, but are not limited to, amine-terminated polyethylene glycols, such as the Jeffamine ED series of products from Huntsman, such as Jeffamine HK-511, Jeffamine ED-600, Jeffamine ED-900, and Jeffamine ED-2003, and amine-terminated polypropylene glycols, such as the Jeffamine D series of products from Huntsman, such as Jeffamine D-230, Jeffamine D-400, Jeffamine D-2000, and Jeffamine D-4000.

[0052] According to formula (V), the amine-containing compound can include or be represented by:

[0053]

[0054] where each p is independently 2 or 3.

[0055] Suitable amine-containing compounds represented by formula (V) of the present application include, but are not limited to, diamines based on amine-terminated polyethylene glycols, such as the Jeffamine EDR series of products from Huntsman, such as Jeffamine EDR-148 and Jeffamine EDR-176.

[0056] According to Formula (VI), the amine-containing compound can comprise or be represented as:

[0057]

[0058] where R is H or C2H5, m = 0 or 1, and a + b + c = 5-85.

[0059] Suitable amine-containing compounds represented by Formula (VI) of the present application include, but are not limited to, amine-terminated propoxylated trimethylolpropane or glycerol, such as the Jeffamine T series of HUNTSMAN, such as Jeffamine T-403, Jeffamine T-3000, and Jeffamine T-5000.

[0060] The amine component can also optionally include a polyamine containing other functional groups or moieties, such as 2,4,6-tris(dimethylaminomethyl)phenol.

[0061] In a preferred embodiment, to achieve faster cure and dry speeds, it can be advantageous to use as the curing agent component an adduct of an amine compound described above, such as a polyetheramine, a polyamide, and / or a polyamine (such as the aliphatic diamines, cycloaliphatic diamines, or aromatic diamines described above) with an epoxy resin. The epoxy resin can be one of those described above, such as a bisphenol F or bisphenol A based epoxide.

[0062] In various embodiments of the present application, a curing accelerator can also be optionally included in the curing agent component of the coating composition of the present application. Curing accelerators are used to promote the reaction between the amine component and the epoxy resin. Exemplary curing accelerators include, but are not limited to, salicylic acid.

[0063] In various embodiments of the present application, the amount of the curing accelerator of the coating composition of the present application is from about 0 to about 3 weight percent, preferably from about 1 to about 2.5 weight percent, and more preferably from about 1.5 to about 2 weight percent, based on the total weight of the curing agent component of the coating composition.

[0064] In some embodiments of the present application, the coating composition of the present application can also include one or more solvents. Any solvent commonly used in the coating art can be used in the present application. Specific examples of solvents include, but are not limited to, propylene glycol monomethyl ether acetate and its derivatives, acetone, amyl propionate, anisole, benzene, butyl acetate, cyclohexane, dialkyl ethers of ethylene glycol, diethylene glycol dibenzoate, dimethyl sulfoxide, dimethylformamide, dimethoxybenzene, ethyl acetate, isopropyl alcohol, isobutyl alcohol, methylcyclohexanone, cyclopentanone, methyl ethyl ketone, methyl isobutyl ketone, methyl propionate, propylene carbonate, tetrahydrofuran, toluene, xylene, benzyl alcohol, 2-methoxyethyl ether, 3-propylene glycol methyl ether, and mixtures thereof.

[0065] In various embodiments of the present application, the amount of one or more solvents of the coating composition of the present application is about 5 to 15 wt.%, preferably about 7 to 12 wt.%, more preferably about 8 to about 11 wt.%, based on the total weight of the coating composition.

[0066] In various embodiments of the present application, the coating composition of the present application can also optionally comprise one or more additives including, but not limited to, thixotropic agents, wetting dispersants, fillers, pigments, and the like.

[0067] Thixotropic agents are used to improve and / or maintain the rheology of the coating composition and prevent the settling of zinc powder particles and other fillers in the coating. In various embodiments of the present application, examples of thixotropic agents in Part A of the coating composition of the present application include colloidal silica, hydrated aluminum silicate (bentonite), aluminum tristearate, aluminum monostearate, xanthan gum, chrysotile, fumed silica, hydrogenated castor oil, organically modified clays, polyamide waxes, and polyethylene waxes, and the like. The amount of thixotropic agent can be selected by one skilled in the art as desired. For example, the amount of thixotropic agent of the coating composition of the present application can be about 0.5 to about 1.5 wt.%, preferably 0.6 to about 1.1 wt.%, based on the total weight of the coating composition.

[0068] Wetting dispersants are capable of improving the dispersibility of zinc powder particles and fillers in the coating. Examples of suitable wetting dispersants include lecithin, amine alkylated polyhydroxy acid amides, substituted amino-terminated polyesters, block polymer copolymers, ethylene-based polymers, and the like. The amount of wetting dispersant in the coating composition of the present application can be about 0.1 to about 0.5 wt.%, preferably about 0.2 to about 0.4 wt.%, based on the total weight of the coating composition.

[0069] In various embodiments of the present application, the coating composition of the present application, particularly Part A of the composition, comprises a filler other than zinc particles. The filler includes, but is not limited to, talc, silica, mica, montmorillonite, kaolin, diatomaceous earth, vermiculite, natural and synthetic zeolites, calcium silicate, aluminum silicate, sodium aluminum silicate, hollow microspheres such as hollow glass microspheres, barium sulfate, calcium carbonate, and the like. In preferred embodiments of the present application, the coating composition of the present application, particularly Part A of the composition, can comprise talc, silica, or hollow microspheres such as hollow glass microspheres as the filler. In further embodiments, the coating composition of the present application, particularly Part A of the composition, can also optionally comprise barium sulfate as the filler. In various embodiments of the present application, the amount of filler in the coating composition of the present application can range from about 2 to about 8% based on the total weight of the coating composition. Particularly preferably, the filler comprises hollow microspheres such as glass microspheres. The amount of hollow microspheres such as hollow glass microspheres is preferably about 1 to 5% based on the total weight of the composition.

[0070] Examples of pigments and / or pigment compositions include, but are not limited to, carbazole dioxazine crude pigments, azo, monoazo, diazo, naphthol AS, salt type (lakes), benzimidazolone, condensation, metal complex, isoindolinone, isoindoline and polycyclic phthalocyanine, quinacridone, perylene, perinone, diketopyrrolo pyrrole, thioindigo, anthraquinone, indathrene, anthrapyrimidine, flavanthrone, pyranthrone, anthraquinonoimidazole, dioxazine, triarylcarbonium, quinophthalone pigments, diketopyrrolo pyrrole red ("DPPBO red"), titanium dioxide, iron oxide, carbon black, carbon fiber, graphite, other conductive pigments, and mixtures thereof.

[0071] In various embodiments of the present application, the amount of pigment and / or pigment composition in the coating composition of the present application can range from about 0.5 to about 5 weight percent, for example, from about 0.5 to about 3 weight percent, based on the total weight of the coating composition.

[0072] The coating composition of the present application can be formulated in a multi-part form, which is a term well known in the art of coatings, which refers to formulating the components of the coating composition into multiple parts or components, and then packaging each part or component in a separate container, such as a moisture resistant container. The multi-part coating composition comprises at least the following two parts:

[0073] Part A, comprising the resin component as described above, zinc particles, and a metal phosphorous salt, wherein the resin component comprises an epoxy resin and a petroleum resin, and the amount of zinc particles is at least 65 weight percent; and

[0074] Part B, comprising a curing agent.

[0075] The preparation of Part A of the coating composition is known to those skilled in the art. For example, at room temperature or slightly elevated temperature, the components in Part A are mixed and stirred in a container to achieve a proper viscosity. Likewise, the preparation of Part B of the coating composition of the present application is also known to those skilled in the art and is similar to the preparation of Part A described above.

[0076] In various embodiments of the present application, the components are mixed prior to using the coating composition of the present application, in the case of a multi-part coating composition, by mixing Part A with Part B. Part A and Part B can be mixed in a stoichiometric ratio of 1 :0.5 to 1 :0.9 of epoxy groups to amine groups. The resulting coating composition is then applied to a substrate. The method of applying the coating composition of the present application to a substrate is not particularly limited. For example, the method of application can include brushing, spraying, dipping, rolling, curtain coating, and the like.

[0077] The substrate to which the coating composition of the present application can be applied is preferably a metal substrate. The metal substrate includes various steel substrates, iron substrates, aluminum substrates, and the like. Advantageously, the coating composition according to the present application can be applied as a primer or a base coat on these substrates.

[0078] In order to explain the present application in more detail, the following examples are given. However, it should be understood that the following examples are for illustration only and should not be considered as limiting the present application to their details. All parts and percentages in the following examples and throughout the specification are by weight unless otherwise indicated.

[0079] Example

[0080] Preparation of binder part A1

[0081] The preparation process of the binder part Al of the present application is as follows: 10 grams of liquid bisphenol A type epoxy resin (NPEL-128E, commercially available from Nan Ya Plastics), 100 grams of solid bisphenol A type epoxy resin (YD-011X75, commercially available from KOTODO), 30 grams of xylene, 17.7 grams of propylene glycol monomethyl ether acetate, and 7.3 grams of isobutyl alcohol are stirred uniformly in a container at room temperature, and 18.1 grams of petroleum resin (SK 120, commercially available from Yuan Liang, Taiwan) is added while stirring and allowed to completely dissolve. Subsequently, 5.3 grams of polyamide wax (Crayvallacultra, commercially available from ARKEMA) and 5.3 grams of organic bentonite (BENTONE SD-2, commercially available from ELEMENTIS SPECIALTIES) are slowly stirred and added, uniformly dispersed, and the temperature is maintained at no more than 40°C. While stirring, 2.7 grams of soybean lecithin (TOPCITHIN 50, commercially available from CARGILL), 19.5 grams of zinc phosphate (commercially available from Jiangsu Shenlong Zinc Industry Co., Ltd.), and 771.9 grams of zinc powder (HX600-II, commercially available from Jiangsu Shenlong Zinc Industry Co., Ltd.) are added, and the temperature is maintained at 55-60°C for 30 minutes. Finally, 38.7 grams of xylene and 19.5 grams of hollow glass microspheres (GLASS BUBBLES VS5500, commercially available from 3M) are added while stirring and uniformly stirred.

[0082] Preparation of binder part A2 (comparative)

[0083] Similar to the preparation process and the amount of use of the binder part Al of the coating composition of the present application described above, the weight ratio of each component is as shown in Table 1, except that no zinc phosphate is used and the amount of use of petroleum resin is increased.

[0084] Preparation of binder part A3

[0085] The base part A3 was prepared as follows: In a vessel, at room temperature, liquid bisphenol-A epoxy resin (NPEL-128E, commercially available from Nan Ya Plastics) 10 g, solid bisphenol-A epoxy resin (YD-011X75, commercially available from KOTOBRA) 119.5 g, xylene 30 g, propylene glycol monomethyl ether acetate 17.7 g, isobutyl alcohol 7.3 g were stirred uniformly and petroleum resin (SK 120, commercially available from Yuan Liang, Taiwan) 18.1 g was added while stirring and allowed to dissolve completely. Polyamide wax (Crayvallac ultra, commercially available from ARKEMA) 5.3 g and organo-bentonite (BENTONE SD-2, commercially available from ELEMENTIS SPECIALTIES) 5.3 g were added slowly with stirring and allowed to disperse uniformly, keeping the temperature below 40 °C. Soy lecithin (TOPCITHIN 50, commercially available from CARGILL) 2.7 g, zinc phosphate (commercially available from Jiangsu Shenlong Zinc Industry Co., Ltd.) 19.5 g, zinc powder (HX600-II, commercially available from Jiangsu Shenlong Zinc Industry Co., Ltd.) 800 g were added with stirring and the temperature was maintained at 55-60 °C for 30 minutes. Finally, xylene 45.1 g, hollow glass microspheres (GLASS BUBBLES VS5500, commercially available from 3M) 19.5 g were added with stirring and allowed to disperse uniformly.

[0086] Preparation of binder part A4

[0087] The base part A4 was prepared as follows: In a vessel, at room temperature, liquid bisphenol-A epoxy resin (NPEL-128E, commercially available from Nan Ya Plastics) 42.5 g, solid bisphenol-A epoxy resin (YD-011X75, commercially available from KOTOBRA) 28.3 g, xylene 30 g, propylene glycol monomethyl ether acetate 17.7 g, isobutyl alcohol 7.3 g were stirred uniformly and petroleum resin (SK 120, commercially available from Yuan Liang, Taiwan) 18.1 g was added while stirring and allowed to dissolve completely. Polyamide wax (Crayvallac ultra, commercially available from ARKEMA) 5.3 g and organo-bentonite (BENTONE SD-2, commercially available from ELEMENTIS SPECIALTIES) 5.3 g were added slowly with stirring and allowed to disperse uniformly, keeping the temperature below 40 °C. Soy lecithin (TOPCITHIN 50, commercially available from CARGILL) 2.7 g, zinc phosphate (commercially available from Jiangsu Shenlong Zinc Industry Co., Ltd.) 19.5 g, zinc powder (HX600-II, commercially available from Jiangsu Shenlong Zinc Industry Co., Ltd.) 752.4 g were added with stirring and the temperature was maintained at 55-60 °C for 30 minutes. Finally, xylene 41.4 g, hollow glass microspheres (GLASS BUBBLES VS5500, commercially available from 3M) 19.5 g were added with stirring and allowed to disperse uniformly.

[0088] Preparation of binder part A5 (comparative)

[0089] The preparation process and the amount of use of the base part A4 of the coating composition of the present application are similar to the above, the weight ratio of each component is shown in Table 1, the difference is that no zinc phosphate is used and the amount of use of petroleum resin is increased.

[0090] Preparation of binder part A6 (comparative)

[0091] The preparation process and the amount of use of the base part A4 of the coating composition of the present application are similar to the above, the weight ratio of each component is shown in Table 1, the difference is that no petroleum resin is used.

[0092] Preparation of binder part A7 (comparative)

[0093] The preparation process and the amount of use of the base part A4 of the coating composition of the present application are similar to the above, the weight ratio of each component is shown in Table 1, the difference is that no petroleum resin, zinc phosphate, hollow glass microspheres are used, and the amount of use of filler talc is increased.

[0094] Preparation of binder parts A8 and A9 (comparative)

[0095] The preparation process and the amount of use of the base part A4 of the coating composition of the present application are similar to the above, the weight ratio of each component is shown in Table 1, the difference is that no petroleum resin, zinc phosphate, hollow glass microspheres are used, and the amount of use of filler talc is increased.

[0096] The base part is prepared by using the components and the amount of use as shown in Table 1 below.

[0097] Table 1: Composition of the base part

[0098]

[0099] Curing agent part B1

[0100] The curing agent part B1 is prepared by using the components and the amount of use as shown in Table 2 below.

[0101] Table 2: Composition of the curing agent part B1

[0102]

[0103] The preparation process of the curing agent B1 is as follows: at room temperature, add the solvent dimethylbenzene and isobutyl alcohol and the polyamide, 2,4,6-tris(dimethylaminomethyl)phenol into an iron tank container and mix uniformly. Add the bisphenol A type solid epoxy resin under stirring. Finally, add the remaining solvent and mix uniformly. After standing at room temperature for at least 3 days, it is used.

[0104] Curing agent part B2

[0105] The components and amounts as shown in Table 3 below were used to prepare the curing agent part B2.

[0106] Table 3: Composition of curing agent part B2

[0107]

[0108] The curing agent part B2 was prepared as follows: At room temperature in a beaker, the solvent xylene and isobutanol and m-xylylenediamine were added and mixed homogenously. The bisphenol F epoxy resin was added under stirring, the temperature was raised to 90-100°C and the reaction was carried out for 1 hour. The temperature was lowered to 70-75°C and the polyoxypropylenetriamine, 2,4,6-tris(dimethylaminomethyl)phenol, benzyl alcohol and the remaining solvent were added and mixed homogenously.

[0109] Curing agent part B3 (comparative)

[0110] The components and amounts as shown in Table 4 below were used to prepare the curing agent part B2.

[0111] Table 4: Composition of curing agent part B3

[0112]

[0113] The curing agent part B3 was prepared as follows: At room temperature in a steel canister, the benzyl alcohol, the solvent xylene and isobutanol and the polyamide, 2,4,6-tris(dimethylaminomethyl)phenol were added and mixed homogenously. The bisphenol A liquid epoxy resin was added under stirring and mixed homogenously. The mixture was stored at room temperature for at least 3 days before use.

[0114] Coating formulation example 1

[0115] At room temperature, the base part Al was combined with the curing agent part Bl, the stoichiometric ratio of base part and curing agent part was 1 :0.75, the volume ratio of base part and curing agent part was 85: 15.

[0116] Coating formulation example 2 (comparative)

[0117] At room temperature, the base part A2 was combined with the curing agent part Bl, the stoichiometric ratio of base part and curing agent part was 1 :0.78, the volume ratio of base part and curing agent part was 85: 15.

[0118] Coating formulation example 3

[0119] At room temperature, the base part A3 was combined with the curing agent part B2, the stoichiometric ratio of base part and curing agent part was 1 :0.76, the volume ratio of base part and curing agent part was 90: 10.

[0120] Coating formulation example 4

[0121] At normal temperature, the base part A4 was combined with the curing agent part B1, the stoichiometric ratio of the base part and the curing agent part was 1 :0.75, and the volume ratio of the base part and the curing agent part was 77.5:22.5.

[0122] Coating formulation example 5 (comparative)

[0123] At normal temperature, the base part A5 was combined with the curing agent part B1, the stoichiometric ratio of the base part and the curing agent part was 1 :0.79, and the volume ratio of the base part and the curing agent part was 80:20.

[0124] Coating formulation example 6 (comparative)

[0125] At normal temperature, the base part A6 was combined with the curing agent part B1, the stoichiometric ratio of the base part and the curing agent part was 1 :0.75, and the volume ratio of the base part and the curing agent part was 80:20.

[0126] Coating formulation example 7 (comparative)

[0127] At normal temperature, the base part A6 was combined with the curing agent part B2, the stoichiometric ratio of the base part and the curing agent part was 1 :0.73, and the volume ratio of the base part and the curing agent part was 90:10.

[0128] Coating formulation example 8 (comparative)

[0129] At normal temperature, the base part A7 was combined with the curing agent part B3, the stoichiometric ratio of the base part and the curing agent part was 1 :0.77, and the volume ratio of the base part and the curing agent part was 80:20.

[0130] Coating formulation example 9 (comparative)

[0131] At normal temperature, the base part A8 was combined with the curing agent part B3, the stoichiometric ratio of the base part and the curing agent part was 1 :0.81, and the volume ratio of the base part and the curing agent part was 80:20.

[0132] Coating formulation example 10 (comparative)

[0133] At normal temperature, the base part A9 was combined with the curing agent part B3, the stoichiometric ratio of the base part and the curing agent part was 1 :0.87, and the volume ratio of the base part and the curing agent part was 80:20.

[0134] Performance test:

[0135] 1. Drying performance test

[0136] The dryability of the paint was tested (ASTM D1640) using a draw down bar with a 150 pm opening to draw down the resulting paint composition onto a glass bar.

[0137] 2. Salt Fog Test ASTM B117

[0138] The paint of each of the above examples was applied to a grit blasted Sa2.5 carbon steel panel of 150 mm X 75 mm X 5 mm (length * width * thickness) at a dry film thickness of 100 microns. The paint film was allowed to fully cure by drying at room temperature for 14 days. The salt fog test was performed according to ASTM B117. The test results are shown in Table 5 below.

[0139] 3. Wet Heat Test ASTM D 2247

[0140] The paint of each of the above examples was applied to a grit blasted Sa2.5 carbon steel panel of 150 mm X 75 mm X 5 mm (length * width * thickness) at a dry film thickness of 100 microns. The paint film was allowed to fully cure by drying at room temperature for 14 days. The salt fog test was performed according to ASTM B117. The test results are shown in Table 5 below.

[0141] 4. Cyclic Aging Test ISO 12944-9

[0142] The paint of each of the above examples was applied to a grit blasted Sa2.5 carbon steel panel of 150 mm X 75 mm X 5 mm (length * width * thickness) at a dry film thickness of 100 microns. The paint film was allowed to fully cure by drying at room temperature for 14 days. The salt fog test was performed according to ASTM B117. The test results are shown in Table 5 below.

[0143] Table 5: Coating test results

[0144]

[0145]

[0146] According to the above various test results, the paint composition of the present application can reduce the density of the zinc-rich epoxy paint by optimizing the ratio of metal phosphates, petroleum resins and epoxy resins, and in some cases by further adding hollow glass microspheres, thereby reducing the amount of zinc powder used, while significantly improving the dryability and corrosion resistance (salt fog test, wet heat test and cyclic aging test).

[0147] Those skilled in the art will readily understand that modifications can be made to the present application without departing from the concepts disclosed in the foregoing description. Thus, the particular aspects described herein are meant to be illustrative only and not limiting as to the scope of the application, which is to be given the full breadth of the appended claims and all equivalents thereof.

Claims

1. A coating composition comprising: - Resin components, which include epoxy resin and petroleum resin; - At least 65% by weight of zinc particles based on the total solids weight of the coating composition; - A metal containing phosphate, wherein the metal as the cation moiety of the metal containing phosphate includes zinc, aluminum, zirconium, or iron; and - Curing agent; The amount of petroleum resin is 0.5-8% by weight based on the total weight of the coating composition, and the amount of epoxy resin is 3-25% by weight based on the total weight of the coating composition, wherein the weight ratio of the epoxy resin to the petroleum resin is in the range of 3-8:1; and The weight ratio of the metal phosphate to the zinc particles is in the range of 1:20 to 1:

60.

2. The coating composition according to claim 1, characterized in that, The coating composition comprises at least 70% by weight of zinc particles.

3. The coating composition according to claim 1, characterized in that, The coating composition comprises at least 75% by weight zinc particles.

4. The coating composition according to claim 1, characterized in that, The coating composition comprises at least 80% by weight zinc particles.

5. The coating composition according to any one of claims 1 to 4, characterized in that, The amount of petroleum resin is 1-8% by weight, based on the total weight of the coating composition.

6. The coating composition according to any one of claims 1 to 4, characterized in that, The amount of petroleum resin is 1.5-5% by weight, based on the total weight of the coating composition.

7. The coating composition according to any one of claims 1 to 4, characterized in that, The weight ratio of the metal phosphate to zinc particles is in the range of 1:25 to 1:

45.

8. The coating composition according to any one of claims 1 to 4, characterized in that, The metal phosphate is selected from phosphates, phosphites, hypophosphites, hydrogen phosphates, dihydrogen phosphates, hydrogen phosphites, dihydrogen phosphites, and polyphosphates, as well as silicon-modified phosphates or polyphosphates.

9. The coating composition according to claim 8, characterized in that, The silicon-modified phosphate or polyphosphate is a silicate-modified phosphate or polyphosphate.

10. The coating composition according to claim 8, characterized in that, The metal phosphate is selected from zinc phosphate, aluminum tripolyphosphate, strontium aluminum polyphosphate, zirconium hydrogen phosphate, and phosphosilicate.

11. The coating composition according to claim 8, characterized in that, The metal containing phosphate is selected from phosphates.

12. The coating composition according to claim 8, characterized in that, The metal containing phosphate is selected from zinc phosphate.

13. The coating composition according to claim 10, characterized in that, The phosphosilicate is zinc strontium calcium phosphosilicate.

14. The coating composition according to any one of claims 1 to 4, characterized in that, The amount of epoxy resin is 5-20% by weight, based on the total weight of the coating composition.

15. The coating composition according to any one of claims 1 to 4, characterized in that, The amount of epoxy resin is 7-15% by weight, based on the total weight of the coating composition.

16. The coating composition according to any one of claims 1 to 4, characterized in that, The epoxy resin includes both liquid epoxy resin and solid epoxy resin.

17. The coating composition according to claim 16, characterized in that, The epoxy resin comprises liquid and solid bisphenol A type epoxy resin.

18. The coating composition according to claim 16, characterized in that, The amount of liquid epoxy resin is 0.5-15% by weight; and the amount of solid epoxy resin is 1-20% by weight.

19. The coating composition according to claim 18, characterized in that, The amount of the liquid epoxy resin is 1-10 by weight.

20. The coating composition according to claim 18, characterized in that, The amount of the liquid epoxy resin is 1-7 by weight.

21. The coating composition according to claim 18, characterized in that, The amount of the solid epoxy resin is 2-15% by weight.

22. The coating composition according to claim 18, characterized in that, The amount of the solid epoxy resin is 2-12 by weight.

23. The coating composition according to any one of claims 1 to 4, characterized in that, The curing agent includes adducts of polyetheramine, polyamide and / or polyamine with epoxy resin.

24. The coating composition according to any one of claims 1 to 4, characterized in that, The coating composition further comprises 1-5% glass microspheres based on the total weight of the composition.

25. A multi-part coating composition comprising at least two of the following parts: Part A comprises the resin component as described in claim 1, zinc particles, and a metal phosphate, wherein the resin component comprises an epoxy resin and a petroleum resin, and the zinc particles comprise at least 65% by weight based on the total solid weight of the coating composition; and Part B comprises the curing agent as described in claim 1.

26. A method for preparing a coating composition, comprising providing at least the resin component, zinc particles, metal phosphate and curing agent as described in claim 1, or providing part A and part B as described in claim 25, each comprising these components, and then mixing them.

27. A substrate coated with the coating composition of claim 1 or the multipart coating composition of claim 25.

28. The substrate according to claim 27, wherein it is a steel and iron structure.

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