Cathodic protection coating composition

Abstract

To provide a coating composition that exhibits excellent cathodic protection even in locations exposed to the atmosphere. [Solution] An electrochemical corrosion protection coating composition (Y) is used, which comprises an ionic polymer (X) having a cationic functional group (B) and having a pH of 5 to 9 at 25°C, preferably having a halogen content of 20 ppm or less of the ionic polymer (X), wherein the cationic functional group (B) is a quaternary ammonium cation, and the counterion of the cationic functional group (B) of the ionic polymer (X) is at least one selected from the group consisting of carboxylic acid anions, phosphate anions, and sulfonate anions.

Description

Technical Field

[0001] The present invention relates to an electrically anticorrosive coating composition.

Background Art

[0002] It is known that the progress of steel corrosion can be suppressed by flowing an anticorrosive current through the steel to lower the potential of the steel to a potential at which it does not corrode. Generally, this method is called the electrochemically cathodic protection method, and the impressed current method and the sacrificial anode method are known. In the impressed current method, the positive electrode of a DC power supply device is used as an auxiliary anode, and the negative electrode is connected to the steel to be protected by a conductor to form an electric circuit, and an anticorrosive current is flowed from the auxiliary anode to the steel. (Patent Document 1) In the sacrificial anode method, a substance having a lower redox potential than the steel to be electrochemically protected, for example, a base metal such as zinc, magnesium, aluminum, or an alloy thereof, is used as a galvanic anode (sacrificial anode). The galvanic anode is connected to the steel by a conductor, and the metal of the galvanic anode is ionized instead of the steel to prevent the corrosion of the steel. That is, the steel to be protected is used as the cathode, a substance having a lower redox potential than the steel is used as the anode to complete a battery, and an anticorrosive current is flowed through the steel due to the potential difference between the two electrodes. (Patent Document 2)

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Disclosure of the Invention

Problems to be Solved by the Invention

[0004] As an external power supply method, a known method involves applying paint to the target material to form a coating and then applying a corrosion-preventive current from an external power source to prevent corrosion. However, this method is ineffective unless a large amount of inorganic materials are used in the paint, which makes it easy for pinholes to form during painting. Rainwater and other elements can then penetrate through these pinholes, causing rust, resulting in insufficient cathodic protection. On the other hand, the galvanic anode method requires contact with water and consumes substances with low oxidation-reduction potential over time, which means it cannot be used in places exposed to the atmosphere. The object of the present invention is to provide a coating composition that exhibits excellent cathodic protection in locations exposed to the atmosphere. [Means for solving the problem]

[0005] The inventors of this invention arrived at this present invention as a result of diligent research to solve the above problems. In other words, the present invention relates to an electrochemical protective coating composition (Y) comprising an ionic polymer (X) having a cationic functional group (B) and a pH of 5 to 9 at 25°C; an electrochemical protective coating film formed from the electrochemical protective coating composition (Y); and an electrochemical protective coating film structure. [Effects of the Invention]

[0006] The cathodic protection coating composition (Y) of the present invention provides the following effects. (1) Excellent cathodic protection in areas exposed to the atmosphere. [Modes for carrying out the invention]

[0007] The present invention will be described in detail below.

[0008] The cathodic protection coating composition (Y) of the present invention is a cathodic protection coating composition comprising an ionic polymer (X) having a cationic functional group (B) and a pH of 5 to 9 at 25°C.

[0009] The ionic polymer (X) is not particularly limited, and any known polymer having a cationic functional group (B) can be used. The cationic functional group (B) is preferably a tertiary ammonium cation or a quaternary ammonium cation, and the concentration of the cationic functional group (B) in the ionic polymer (X) is preferably 0.05 mol / kg or more from the viewpoint of cathodic protection, and preferably 2.5 mol / kg or less from the viewpoint of ease of coating. Examples of known polymers include acrylic resins.

[0010] Examples of acrylic resins include polymers obtained by homopolymerizing or copolymerizing monomers having cationic functional groups and polymerizable double bonds. Examples of monomers having cationic functional groups and polymerizable double bonds include nitrogen atom-containing monomers (a), while examples of other monomers having polymerizable double bonds include aliphatic hydrocarbon monomers (b), alicyclic hydrocarbon monomers (c), aromatic hydrocarbon monomers (d), alkyl esters (e), vinyl esters (f), and the like.

[0011] Examples of nitrogen atom-containing monomers (a) include the following monomers: monomers containing amide groups (a1) and monomers containing primary to tertiary amino groups (a2). Examples of amide group-containing monomers (a1) include (meth)acrylamide, monoalkyl(meth)acrylamide, monoalkylaminoalkyl(meth)acrylamide [having an aminoalkyl group (2-6 carbon atoms) with one C1-4 alkyl group bonded to the nitrogen atom; for example, N-methylaminoethyl(meth)acrylamide, N-ethylaminoethyl(meth)acrylamide, N-isopropylamino-n-butyl(meth)acrylamide, and Nn- or isobutylamino-n-butyl(meth)acrylamide], and dialkyl(meth)acrylamide [having two C1-4 alkyl groups bonded to the nitrogen atom; for example, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-diisopropyl Examples include di(meth)acrylamide and N,N-di-n-butyl(meth)acrylamide, etc., dialkylaminoalkyl(meth)acrylamide [those having an aminoalkyl group (2-6 carbon atoms) in which two alkyl groups with 1-4 carbon atoms are bonded to a nitrogen atom; for example, N,N-dimethylaminoethyl(meth)acrylamide, N,N-diethylaminoethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide and N,N-di-n-butylaminobutyl(meth)acrylamide, etc.], and N-vinyl carboxylic acid amides [N-vinylformamide, N-vinylacetamide, N-vinyl-n- or isopropionylamide and N-vinylhydroxyacetamide, etc.], which have a nitrogen atom only in the amide group. In this invention, "(meth)acrylate" means "acrylate and / or methacrylate," and "(meth)acryloyl" means "acryloyl and / or methacryloyl."

[0012] Examples of primary to tertiary amino group-containing monomers (a2) include primary amino group-containing vinyl monomers {alkenylamines with 3 to 6 carbon atoms [(meth)allylamine and clotylamine, etc.], aminoalkyl (2 to 6 carbon atoms) (meth)acrylates [aminoethyl (meth)acrylate, etc.]}, secondary amino group-containing vinyl monomers {monoalkylaminoalkyl (meth)acrylates [those having an aminoalkyl group (2 to 6 carbon atoms) in which one alkyl group of 1 to 6 carbon atoms is bonded to the nitrogen atom; for example, t-butylaminoethyl (meth)acrylate and methylaminoethyl (meth)acrylate, etc.], dialkenylamines with 6 to 12 carbon atoms [di(meth)allylamine, etc.]}, and tertiary amino group-containing vinyl monomers {dialkylaminoalkyl (meth)acrylates [those having one alkyl group of 1 to 6 carbon atoms bonded to the nitrogen atom Examples include aminoalkyl groups (with 2 to 6 carbon atoms) formed by the bonding of two alkyl groups with 1 to 6 carbon atoms; for example, dimethylaminoethyl (meth)acrylate, 2-(dimethylamino)ethyl-methacrylate, and diethylaminoethyl (meth)acrylate, etc.; alicyclic (meth)acrylates having a nitrogen atom [such as morpholinoethyl (meth)acrylate]; aromatic vinyl monomers [such as N,N-diphenylaminoethyl (meth)acrylamide, N,N-dimethylaminostyrene, 4-vinylpyridine, 2-vinylpyridine, 1-allylimidazole, N-vinylpyrrole, N-vinylpyrrolidone, and N-vinylthiopyrrolidone]; and hydrochloride salts, sulfates, phosphates, or lower alkyl (with 1 to 8 carbon atoms) monocarboxylic acid (such as acetic acid and propionic acid) salts thereof.

[0013] Examples of aliphatic hydrocarbon monomers (b) include alkenes having 2 to 20 carbon atoms (ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, and octadecene, etc.) and alkadienes having 4 to 12 carbon atoms (butadiene, isoprene, 1,4-pentadiene, 1,6-heptadiene, and 1,7-octadiene, etc.).

[0014] Examples of alicyclic hydrocarbon monomers (c) include cyclohexene, (di)cyclopentadiene, pinene, limonene, vinylcyclohexene, and ethylidenebicycloheptene.

[0015] Examples of aromatic hydrocarbon monomers (d) include styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, 4-ethylstyrene, 4-isopropylstyrene, 4-butylstyrene, 4-phenylstyrene, 4-cyclohexylstyrene, 4-benzylstyrene, indene, 4-clotylbenzene, and 2-vinylnaphthalene.

[0016] Alkyl ester(e) includes (meth)acrylate esters having an alkyl group with 1 to 30 carbon atoms [(methyl meth)acrylate, (ethyl meth)acrylate, (propyl meth)acrylate, (butyl meth)acrylate, (hexyl meth)acrylate, (octyl meth)acrylate, (dodecyl meth)acrylate, (tridecyl meth)acrylate, (tetradecyl meth)acrylate, (pentadecyl meth)acrylate, (hexadecyl meth)acrylate, (hepta meth)acrylate] Examples include decyl, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, henicosyl (meth)acrylate, docosyl (meth)acrylate, tricosyl (meth)acrylate, tetracosyl (meth)acrylate, pentacosyl (meth)acrylate, hexacosyl (meth)acrylate, heptacosyl (meth)acrylate, octacosyl (meth)acrylate, nonacosyl (meth)acrylate, and triacontyl (meth)acrylate.

[0017] Examples of vinyl esters (f) include vinyl esters of saturated fatty acids having 2 to 12 carbon atoms (such as vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl octanoate).

[0018] Of the above-mentioned monomers having cationic functional groups and polymerizable double bonds, from the viewpoint of cathodic protection, nitrogen atom-containing monomers (a) are preferred, more preferably primary to tertiary amino group-containing monomers (a2), even more preferably tertiary amino group-containing vinyl monomers, and particularly preferably dialkylaminoalkyl (meth)acrylate and 1-allylimidazole.

[0019] Among the monomers having the above-mentioned other polymerizable double bonds, from the viewpoint of corrosion protection, aromatic hydrocarbon monomers (d) and alkyl esters (e) are preferable, more preferably styrene and (meth)acrylic acid esters having an alkyl group with 1 to 30 carbon atoms, and still more preferably styrene, methyl methacrylate, and butyl acrylate.

[0020] The weight ratio of the monomer having a cationic functional group and a polymerizable double bond constituting the acrylic resin is preferably 1 to 20% by weight based on the total weight of the constituent monomers of the acrylic resin.

[0021] Specific examples of the acrylic resin preferably include a copolymer obtained by copolymerizing a monomer (a2) containing a primary to tertiary amino group, an aromatic hydrocarbon monomer (d), and a (meth)acrylic acid ester having an alkyl group with 1 to 30 carbon atoms, and particularly preferably include a copolymer obtained by copolymerizing a vinyl monomer containing a tertiary amino group, styrene, and methyl (meth)acrylate or butyl (meth)acrylate.

[0022] The counter ion of the cationic functional group (B) of the ionic polymer (X) is not particularly limited, and among known anions, an anion capable of forming an ionic polymer can be used. Examples of known anions include anions obtained by removing at least one proton from an acid having a chemical formula weight of 40 to 500 exemplified below, and at least one selected from the group consisting of carboxylic acid anions, phosphate anions, and sulfonic acid anions is preferable.

[0023] Carboxylic acids include monocarboxylic acids {aliphatic monocarboxylic acids with 1 to 30 carbon atoms [saturated monocarboxylic acids (formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, stearic acid, and behenic acid, etc.) and unsaturated monocarboxylic acids (acrylic acid, methacrylic acid, and oleic acid, etc.)] and aromatic monocarboxylic acids (benzoic acid, cinnamic acid, and naphthoic acid, etc.)}, and polycarboxylic acids (divalent to tetravalent polycarboxylic acids) {aliphatic Examples include polycarboxylic acids [saturated polycarboxylic acids (oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid, etc.), unsaturated polycarboxylic acids (maleic acid, fumaric acid, and itaconic acid, etc.)], aromatic polycarboxylic acids [phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and pyromellitic acid, etc.], aliphatic oxycarboxylic acids [glycolic acid, lactic acid, and tartaric acid, etc.], aromatic oxycarboxylic acids [salicylic acid and mandelic acid, etc.], etc.].

[0024] Examples of sulfonic acids include alkyl sulfonic acids (alkyl groups with 1 to 30 carbon atoms) and alkylbenzene sulfonic acids (alkyl groups with 1 to 30 carbon atoms, such as dodecylbenzenesulfonic acid).

[0025] Examples of phosphoric acid include phosphate esters [mono- or dialkyl phosphates with 1 to 8 or more carbon atoms in the alkyl group (monobutyl phosphate, monooctyl phosphate, dibutyl phosphate, dioctyl phosphate, etc.)].

[0026] Other acids include hydrohalogens (HCl, HBr, etc.), sulfuric acid, HClO4, HBF4, HPF6, HAsF6, HSbF6, and others.

[0027] Among the ionic polymers (X), polymers having primary to tertiary ammonium cations as cationic functional groups include copolymers containing primary to tertiary amino group-containing monomers (a2) as constituent monomers, which are neutralized with the aforementioned acid. Examples of combinations of copolymers obtained by copolymerizing ionic polymers (X), which include preferred polymers such as primary to tertiary amino group-containing monomers (a2), aromatic hydrocarbon monomers (d), and (meth)acrylic acid esters having alkyl groups with 1 to 30 carbon atoms, with the acid used as the counterion include copolymers of butyl acrylate, styrene, methyl methacrylate, and 2-(dimethylamino)ethyl methacrylate and copolymers of dodecylbenzenesulfonic acid, butyl acrylate, styrene, 2-(dimethylamino)ethyl methacrylate and copolymers of acetic acid, butyl acrylate, styrene, methyl methacrylate, and 1-allylimidazole and copolymers of dodecylbenzenesulfonic acid, styrene, and 2-(dimethylamino)ethyl methacrylate with dibutyl phosphate, and copolymers of butyl acrylate, styrene, methyl methacrylate, and 1-allylimidazole with dibutyl phosphate.

[0028] Among the ionic polymers (X), polymers having a quaternary ammonium cation as a cationic functional group include those obtained by quaternizing a copolymer containing primary to tertiary amino group-containing monomers (a2) with a known quaternizing agent (diethyl sulfate, dibutyl sulfate, etc.). Among the ionic polymers (X), preferred polymers include copolymers obtained by copolymerizing primary to tertiary amino group-containing monomers (a2), aromatic hydrocarbon monomers (d), and (meth)acrylic acid esters having alkyl groups with 1 to 30 carbon atoms, and combinations of these copolymers with quaternizing agents. Examples include copolymers of butyl acrylate, styrene, and 2-(dimethylamino)ethyl methacrylate with diethyl sulfate, and copolymers of butyl acrylate, styrene, methyl methacrylate, and 1-allylimidazole with diethyl sulfate.

[0029] The ionic polymer (X) may also contain pH adjusters and inorganic salts such as nitrates and phosphates as components other than those mentioned above.

[0030] The ionic polymer (X) has a pH of 5 to 9 at 25°C, preferably 6.0 to 8.5, and more preferably 7.0 to 8.0, from the viewpoint of corrosion resistance. The pH of the ionic polymer (X) is particularly important from the viewpoint of corrosion resistance to metals; if the pH is less than 5, it will cause the metal surface to penetrate, and if the pH is greater than 9, the chemical polishing power will decrease. If the pH is outside the range of 5 to 9, the composition ratio of acid and amine is biased towards either acid or amine, so the pH can be adjusted by measuring the acid value or amine value of the ionic polymer (X) and adding a counterion or acid component corresponding to the obtained value.

[0031] The pH of the ionic polymer (X) is measured by the glass electrode method in accordance with the method described in JIS Z8802, using a prepared solution in which the ionic polymer (X) is dissolved in a solution of water and isopropanol mixed in a volume ratio of 60:100 to a concentration of 16% by weight.

[0032] From the viewpoint of corrosion prevention, the halogen content of the ionic polymer (X) is preferably 20 ppm or less, and more preferably 10 ppm or less. If the halogen content is within this range, metal corrosion due to halogens can be prevented. Unless intentionally added, halogens are mainly present in the raw materials used when synthesizing ionic polymers (X), and when halogenated salts are used as cations. If the halogen content is higher than 20 ppm, the halogen content can be reduced by dissolving it in acetone or the like and then passing it through a column packed with alumina, for example.

[0033] The halogen content of the ionic polymer (X) can be determined by diluting the ionic polymer (X) 100 to 10 times with ultrapure water, performing ion chromatography under the following conditions to determine the content of various halogens, and then calculating the sum of the obtained halogen content. Equipment: Ion chromatograph (Thermo SCIENTIFIC: Dionex ICS-5000+DC) Column: IonPack AS-22 + IonPack AG-22 Suppressor: ARES 4mm Solvent: Mixed solution of 4.5 mM sodium carbonate and 1 mM sodium bicarbonate. Standard sample: Anion mixed standard solution IV (Kanto Chemical) Measurement temperature: 35℃ Flow rate: 1.2mL / min

[0034] The weight-average molecular weight of the ionic polymer (X) is preferably between 5,000 and 300,000 from the viewpoint of coating film strength and coating viscosity.

[0035] From the viewpoint of chemical polishing, the total amine value of the ionic polymer (X) is preferably 2 mg KOH / g or less. If the total amine value is greater than 2 mg KOH / g, the amine value can be reduced by adding an acid component equal to the acid value corresponding to the value.

[0036] The total amine number of the ionic polymer (X) was measured according to the method of ASTM D2074.

[0037] From the viewpoint of corrosion prevention, the acid value of the ionic polymer (X) is preferably 30 mg KOH / g or less. Having an acid value of 30 mg KOH / g or less suppresses the reduction in corrosion resistance due to metal corrosion caused by acid.

[0038] The acid value of ionic polymer (X) can be adjusted by adding a basic compound. The acid value of ionic polymer (X) is measured by methods such as JIS K 0070.

[0039] The method for producing the ionic polymer (X) is not particularly limited, but for example, when using acrylic resin, one method is to obtain the acrylic resin by solution polymerization of the above monomer in a solvent in the presence of a polymerization catalyst, followed by salt exchange. Examples of solvents include toluene, xylene, alkylbenzenes having 9 to 10 carbon atoms, methyl ethyl ketone, ethyl acetate, 2-propanol, and base oils described later. Polymerization catalysts include azo catalysts (such as azobisisobutyronitrile and azobisvaleronitrile), peroxide catalysts (such as benzoyl peroxide, cumyl peroxide, and lauryl peroxide), and redox catalysts (such as a mixture of benzoyl peroxide and a tertiary amine). Furthermore, known chain transfer agents (such as alkyl mercaptans with 2 to 20 carbon atoms) can be used as needed. The polymerization temperature is preferably 25 to 140°C, and more preferably 50 to 120°C. In addition to the solution polymerization described above, acrylic resins can also be obtained by bulk polymerization, emulsion polymerization, or suspension polymerization. The polymerization form of the acrylic resin may be either random addition polymerization or alternating copolymerization, and may also be either graft copolymerization or block copolymerization.

[0040] The cathodic protection coating composition (Y) may also contain solvents and additives as components other than the ionic polymer (X).

[0041] Examples of solvents include ester solvents (ethyl acetate, butyl acetate, and ethyl cellosolve acetate, etc.), ketone solvents (acetone, methyl ethyl ketone, and methyl isobutyl ketone, etc.), ether solvents (dioxane, tetrahydrofuran, and propylene glycol monomethyl ether, etc.), aliphatic hydrocarbon solvents (n-hexane, n-heptane, cyclohexane, methylcyclohexane, etc.), and alcohol solvents (ethanol, methanol, n-propyl alcohol, isopropyl alcohol, and n-butyl alcohol (n-butanol), etc.).

[0042] Examples of additives include pigments, curing agents, diluents, leveling agents such as acrylic resins and silicone resins, silicone-based and acrylic-based anti-repellent agents, anti-skinning agents, thixotropes, defoaming agents, anti-separation agents, smoothing agents, wetting agents, dispersants, thickeners, anti-settling agents, polymerization inhibitors, structural viscosity modifiers, electrostatic coating properties improvers, anti-sagging agents, curing accelerators, antioxidants, light stabilizers, flame retardants, and coating aids. Preferred examples of light stabilizers and antioxidants include compounds described in Japanese Patent Application Publication No. 2004-117997.

[0043] The content of the ionic polymer (X) in the electrochemical corrosion protection coating composition (Y) of the present invention is preferably 20 to 100% by weight, and more preferably 30 to 100% by weight, based on the weight of (Y).

[0044] The solvent content in the electrochemical corrosion protection coating composition (Y) of the present invention is preferably 0 to 80% by weight, and more preferably 0 to 70% by weight, based on the weight of (Y).

[0045] The additive content in the cathodic protection coating composition (Y) of the present invention is preferably 0 to 20% by weight, and more preferably 0 to 10% by weight, based on the weight of (Y).

[0046] The electrochemical corrosion protection coating composition (Y) of the present invention may contain water, but from the viewpoint of corrosion protection, the water content is preferably 2.0% by weight or less, and more preferably 1.0% by weight or less, relative to the ionic polymer (X). If the water content exceeds 2.0% by weight, the water may adhere to the metal surface to be protected, causing hydroxide formation and potentially reducing corrosion protection.

[0047] The water content can be evaluated using the Karl Fischer assay.

[0048] The halogen content of the cathodic protection coating composition (Y) of the present invention is preferably 20 ppm or less, and more preferably 10 ppm or less, from the viewpoint of corrosion prevention. If the halogen content is within this range, metal corrosion caused by halogens can be suppressed. Unless intentionally added, halogens are mainly present in the raw materials used when synthesizing ionic polymers (X), and when halogenated salts are used as cations. If the halogen content is higher than 20 ppm, the halogen content can be reduced by dissolving it in acetone or the like and then passing it through a column packed with alumina, for example.

[0049] The halogen content of the corrosion-resistant coating composition (Y) can be measured in the same manner as that of the ionic polymer (X).

[0050] The corrosion-preventive coating composition (Y) of the present invention can be obtained by using the ionic polymer (X) as is, or by melt-mixing or solution-mixing additives as needed. As a melt-mixing method, generally, each component in pellet form, powder form, or liquid form can be mixed in a suitable mixer (such as a Henschel mixer), and then mixed in an extruder to form pellets. As a solution-mixing method, one or both of (X) and the additive can be mixed in the form of a solution in a solvent. Examples of solvents used in solution mixing include alcohols [e.g., monoalcohols such as methanol, ethanol, and isopropanol, and diols such as ethylene glycol and propylene glycol], ethers [e.g., diethylene glycol, tetrahydrofuran, and 1,4-dioxane], ketones [e.g., acetone, methyl ethyl ketone, methyl isopropyl ketone, and methyl isobutyl ketone], and esters [ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, and butyl cellosolve acetate]. This includes amides [e.g., dimethylformamide, diethylformamide, dimethylacetamide, and N-methylpyrrolidone], aromatic hydrocarbons [e.g., benzene, toluene, xylene, ethylbenzene, triethylbenzene, amylbenzene, diamylbenzene, amyltoluene, diphenylethane, and tetralin], aliphatic hydrocarbons [e.g., hexane, heptane, octane, and decane], alicyclic hydrocarbons [e.g., cyclohexane, cyclohexene, methylcyclohexane, and decalin], and other solvents, as well as mixtures of two or more of these.

[0051] The electrochemical corrosion protection coating of the present invention is an electrochemical corrosion protection coating formed from the above-mentioned electrochemical corrosion protection coating composition (Y). Similar to the case in which conventional electrochemical corrosion protection paints are formed from conventional electrochemical corrosion protection coating compositions, the electrochemical corrosion protection coating of the present invention is formed by uniformly applying the electrochemical corrosion protection coating composition of the present invention to an object.

[0052] The thickness of the electrochemical protective coating of the present invention is not particularly limited and can be set to an appropriate range depending on the characteristics of the electrochemical protective coating of the present invention (e.g., coating wear rate) and application (type of substrate, period of use, etc.). For example, a thickness of 30 to 10,000 μm is preferred immediately after formation.

[0053] The electrochemical corrosion protection coating structure of the present invention is a coating structure in which a conductive coating is laminated on the upper surface of the electrochemical corrosion protection coating. Examples of conductive coatings include a coating obtained by dispersing conductive substances such as nickel, zinc, conductive carbon, and conductive polymers in an organic solvent to form a paste, and then applying the resulting paste by a coating method such as gravure coating, bar coating, or screen coating, and then drying it. The electrochemical corrosion protection coating structure in which a conductive coating is laminated on the upper surface of the electrochemical corrosion protection coating has excellent corrosion resistance. [Examples]

[0054] The following describes embodiments of the present invention, but the present invention is not limited to these embodiments. In the following, "parts" refers to parts by weight.

[0055] <Example 1> 2000 parts of ethyl acetate were charged into a stainless steel pressure-resistant reaction vessel equipped with a stirrer, thermometer, heating / cooling device, nitrogen inlet tube, and depressurization device. Under stirring, nitrogen was supplied to replace the nitrogen in the reaction vessel (gas phase oxygen concentration of 400 ppm or less). After raising the temperature to 70°C while blowing nitrogen into the system, a solution was prepared by mixing 400 parts of butyl acrylate [product name "butyl acrylate", manufactured by Mitsubishi Chemical Corporation, molecular weight 128], 400 parts of styrene [product name "styrene monomer", manufactured by Asahi Kasei Corporation, molecular weight 104], and 200 parts of 2-(dimethylamino)ethyl methacrylate [product name "methacrylate DMA", manufactured by Sanyo Chemical Industries, Ltd., molecular weight 157]. 8 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) [product name "V-65", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., molecular weight 248] were simultaneously added dropwise over 2 hours, and the mixture was stirred at 70°C for 4 hours to carry out the polymerization reaction. Next, 190 parts of diethyl sulfuric acid were added, and the mixture was stirred at 50°C for 4 hours to obtain an electrochemical corrosion protection coating composition (Y-1) containing an ionic polymer (X-1).

[0056] <Example 2> 2000 parts of ethyl acetate were charged into a stainless steel pressure-resistant reaction vessel equipped with a stirrer, thermometer, heating / cooling device, nitrogen inlet tube, and depressurization device. Under stirring, nitrogen was supplied to replace the nitrogen in the reaction vessel (gas phase oxygen concentration of 400 ppm or less). After raising the temperature to 70°C while blowing nitrogen into the system, a solution of 350 parts of styrene [product name "Styrene Monomer", manufactured by Asahi Kasei Corporation, molecular weight 104], 600 parts of methyl methacrylate [product name "Acryester M", manufactured by Mitsubishi Chemical Corporation, molecular weight 100], and 150 parts of 2-(dimethylamino)ethyl methacrylate [product name "Methacrylate DMA", manufactured by Sanyo Chemical Industries, Ltd., molecular weight 157] was simultaneously added dropwise over 2 hours to 6 parts of azobisisobutyronitrile [product name "V-601", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., molecular weight 164]. The polymerization reaction was then carried out by stirring at 70°C for 4 hours. Next, 300 parts of dodecylbenzenesulfonic acid were added, and the mixture was stirred at 50°C for 4 hours to obtain an electrochemical corrosion protection coating composition (Y-2) containing an ionic polymer (X-2).

[0057] <Example 3> 2000 parts of ethyl acetate were charged into a stainless steel pressure-resistant reaction vessel equipped with a stirrer, thermometer, heating / cooling device, nitrogen inlet tube, and depressurization device. Under stirring, nitrogen was supplied to replace the nitrogen in the reaction vessel (gas phase oxygen concentration of 400 ppm or less). After raising the temperature to 70°C while blowing nitrogen into the system, a solution of 800 parts of butyl acrylate [product name "butyl acrylate", manufactured by Mitsubishi Chemical Corporation, molecular weight 128], 170 parts of styrene [product name "styrene monomer", manufactured by Asahi Kasei Corporation, molecular weight 104], and 30 parts of 2-(dimethylamino)ethyl methacrylate [product name "methacrylate DMA", manufactured by Sanyo Chemical Industries, Ltd., molecular weight 157] was simultaneously added dropwise over 2 hours to azobisisobutyronitrile [product name "V-601", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., molecular weight 164]. The polymerization reaction was then carried out by stirring at 70°C for 4 hours. Next, 11 parts of acetic acid were added, and the mixture was stirred at 50°C for 4 hours to obtain an electrochemical corrosion protection coating composition (Y-3) containing an ionic polymer (X-3).

[0058] <Example 4> 2000 parts of ethyl acetate were charged into a stainless steel pressure-resistant reaction vessel equipped with a stirrer, thermometer, heating / cooling device, nitrogen inlet tube, and depressurization device. Under stirring, nitrogen was supplied to replace the nitrogen in the reaction vessel (gas phase oxygen concentration of 400 ppm or less). After raising the temperature to 70°C while blowing nitrogen into the system, a solution was prepared by mixing 290 parts of butyl acrylate [product name "butyl acrylate", manufactured by Mitsubishi Chemical Corporation, molecular weight 128], 500 parts of styrene [product name "styrene monomer", manufactured by Asahi Kasei Corporation, molecular weight 104], 200 parts of methyl methacrylate [product name "Acryester M", manufactured by Mitsubishi Chemical Corporation, molecular weight 100], and 10 parts of 1-alliumidazole [product name "1-alliumidazole", manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 108]. This solution was then simultaneously added dropwise over 2 hours, and the polymerization reaction was carried out by stirring at 70°C for 4 hours. Next, 58 parts of dodecylbenzenesulfonic acid were added, and the mixture was stirred at 50°C for 4 hours to obtain an electrochemical corrosion protection coating composition (Y-4) containing an ionic polymer (X-4).

[0059] <Example 5> 2000 parts of ethyl acetate were charged into a stainless steel pressure-resistant reaction vessel equipped with a stirrer, thermometer, heating / cooling device, nitrogen inlet tube, and depressurization device. Under stirring, nitrogen was supplied to replace the nitrogen in the reaction vessel (gas phase oxygen concentration of 400 ppm or less). After raising the temperature to 70°C while blowing nitrogen into the system, a solution was prepared by mixing 200 parts of butyl acrylate [product name "butyl acrylate", manufactured by Mitsubishi Chemical Corporation, molecular weight 128], 450 parts of styrene [product name "styrene monomer", manufactured by Asahi Kasei Corporation, molecular weight 104], 320 parts of methyl methacrylate [product name "Acryester M", manufactured by Mitsubishi Chemical Corporation, molecular weight 100], and 30 parts of 1-alliumidazole [product name "1-alliumidazole", manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 108]. 8 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) [product name "V-65", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., molecular weight 248] were simultaneously added dropwise over 2 hours, and the polymerization reaction was carried out by stirring at 70°C for 4 hours. Next, 83 parts of diethyl sulfuric acid were added, and the mixture was stirred at 50°C for 4 hours to obtain an electrochemical corrosion protection coating composition (Y-5) containing an ionic polymer (X-5).

[0060] <Example 6> 2000 parts of ethyl acetate were charged into a stainless steel pressure-resistant reaction vessel equipped with a stirrer, thermometer, heating / cooling device, nitrogen inlet tube, and depressurization device. Under stirring, nitrogen was supplied to replace the nitrogen in the reaction vessel (gas phase oxygen concentration of 400 ppm or less). After raising the temperature to 70°C while blowing nitrogen into the system, a solution was prepared by mixing 400 parts of butyl acrylate [product name "Butyl Acrylate", manufactured by Mitsubishi Chemical Corporation, molecular weight 128], 400 parts of styrene [product name "Styrene Monomer", manufactured by Asahi Kasei Corporation, molecular weight 104], and 200 parts of 2-(dimethylamino)ethyl methacrylate [product name "Methacrylate DMA", manufactured by Sanyo Chemical Industries, Ltd., molecular weight 157]. 8 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) [product name "V-65", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., molecular weight 248] were simultaneously added dropwise over 2 hours, and the mixture was stirred at 70°C for 4 hours to carry out the polymerization reaction. Next, 260 parts of dibutyl phosphate were added, and the mixture was stirred at 50°C for 4 hours to obtain an electrochemical corrosion protection coating composition (Y-6) containing an ionic polymer (X-6).

[0061] <Example 7> 2000 parts of ethyl acetate were charged into a stainless steel pressure-resistant reaction vessel equipped with a stirrer, thermometer, heating / cooling device, nitrogen inlet tube, and depressurization device. Under stirring, nitrogen was supplied to replace the nitrogen in the reaction vessel (gas phase oxygen concentration of 400 ppm or less). After raising the temperature to 70°C while blowing nitrogen into the system, a solution was prepared by mixing 200 parts of butyl acrylate [product name "butyl acrylate", manufactured by Mitsubishi Chemical Corporation, molecular weight 128], 450 parts of styrene [product name "styrene monomer", manufactured by Asahi Kasei Corporation, molecular weight 104], 320 parts of methyl methacrylate [product name "Acryester M", manufactured by Mitsubishi Chemical Corporation, molecular weight 100], and 30 parts of 1-alliumidazole [product name "1-alliumidazole", manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 108]. 8 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) [product name "V-65", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., molecular weight 248] were simultaneously added dropwise over 2 hours, and the polymerization reaction was carried out by stirring at 70°C for 4 hours. Next, 113 parts of dibutyl phosphate were added, and the mixture was stirred at 50°C for 4 hours to obtain an electrochemical corrosion protection coating composition (Y-7) containing an ionic polymer (X-7).

[0062] <Comparative Example 1> 2000 parts of ethyl acetate were charged into a stainless steel pressure-resistant reaction vessel equipped with a stirrer, thermometer, heating / cooling device, nitrogen inlet tube, and depressurization device. Under stirring, nitrogen was supplied to replace the nitrogen in the reaction vessel (gas phase oxygen concentration of 400 ppm or less). After raising the temperature to 70°C while blowing nitrogen into the system, a solution was prepared by mixing 400 parts of butyl acrylate [product name "butyl acrylate", manufactured by Mitsubishi Chemical Corporation, molecular weight 128], 400 parts of styrene [product name "styrene monomer", manufactured by Asahi Kasei Corporation, molecular weight 104], and 200 parts of 2-(dimethylamino)ethyl methacrylate [product name "methacrylate DMA", manufactured by Sanyo Chemical Industries, Ltd., molecular weight 157]. 8 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) [product name "V-65", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., molecular weight 248] were simultaneously added dropwise over 2 hours. The mixture was then stirred at 70°C for 4 hours to carry out the polymerization reaction, obtaining an electrochemical corrosion protection coating composition (ratio Y-1) containing an ionic polymer (ratio X-1).

[0063] <Comparative Example 2> 2000 parts of ethyl acetate were charged into a stainless steel pressure-resistant reaction vessel equipped with a stirrer, thermometer, heating / cooling device, nitrogen inlet tube, and depressurization device. Under stirring, nitrogen was supplied to replace the nitrogen in the reaction vessel (gas phase oxygen concentration of 400 ppm or less). After raising the temperature to 70°C while blowing nitrogen into the system, a solution was prepared by mixing 290 parts of butyl acrylate [product name "butyl acrylate", manufactured by Mitsubishi Chemical Corporation, molecular weight 128], 500 parts of styrene [product name "styrene monomer", manufactured by Asahi Kasei Corporation, molecular weight 104], 200 parts of methyl methacrylate [product name "Acryester M", manufactured by Mitsubishi Chemical Corporation, molecular weight 100], and 10 parts of 1-alliumidazole [product name "1-alliumidazole", manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 108]. This solution was then simultaneously added dropwise over 2 hours to 8 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) [product name "V-65", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., molecular weight 248]. The mixture was then stirred at 70°C for 4 hours to carry out the polymerization reaction and obtain an electrochemical corrosion protection coating composition (ratio Y-2) containing an ionic polymer (ratio X-2).

[0064] <Examples 1-7, Comparative Examples 1 and 2> For the cathodic protection coating compositions (Y) containing the ionic polymer (X) of Examples 1-7 and Comparative Examples 1 and 2, the water content, pH, and halogen content were measured, and the coating appearance, cathodic protection, heat and humidity resistance, and rust prevention were evaluated using the following test methods. The results are shown in Table 1.

[0065] [Table 1]

[0066] (1) Evaluation of the appearance of the coating film A stainless steel plate (material: SUS304, 1mm thick x 60mm long x 80mm wide) was immersed in 10% hydrochloric acid in a PP tray for 1 minute. After wiping the surface with paper, it was left to stand for 1 week in a constant temperature and humidity chamber at 40°C and 85% humidity to create a test piece with red rust. The prepared test specimens were coated with the cathodic protection coating compositions described in Examples 1-7 and Comparative Examples 1 and 2 using a squeegee to achieve a coating thickness of 190-210 μm, and then dried overnight. The appearance of the coating after drying was visually evaluated with ○ and × according to the following criteria. ○: No exposure of the test specimen or localized thickness variations are observed in the coating. ×: The coating shows exposure of the test specimen and localized unevenness in thickness.

[0067] (2) Cathodic protection test A stainless steel plate (material: SUS304, 1mm thick x 60mm long x 80mm wide) was immersed in 10% hydrochloric acid in a PP tray for 1 minute. After wiping the surface with paper, it was left to stand for 1 week in a constant temperature and humidity chamber at 40°C and 85% humidity to create a test piece with red rust. The prepared test specimens were coated with the cathodic protection coating compositions described in Examples 1-7 and Comparative Examples 1 and 2 on half of each specimen. Next, a zinc plate was placed on the coated surface via a separator. The uncoated end of the test specimen was connected to the cathode of a battery via a lead wire, and the zinc plate was connected to the anode of the battery via a lead wire. A voltage of 6.16V was applied for one month in a constant temperature and humidity chamber at 30°C and 50% humidity. After standing, the coated surface was removed with acetone solvent, and the degree of red rust removal was visually evaluated on the following four-point scale. ◎: Red rust can be restored to black rust and / or iron at a rate of 95% or more relative to the area. ○: Red rust has a recovery rate of 80% or more but less than 95% of the area to black rust and / or iron. △: Red rust has a recovery rate of 60% or more but less than 80% of the area to black rust and / or iron. ×: Red rust has a recovery rate of less than 60% of the area to black rust and / or iron. The area was measured using an Olympus DSX500 digital microscope, and the restoration rate was calculated as (area of ​​rust before testing - area of ​​rust after testing) / (area of ​​rust before testing) × 100 (%).

[0068] (3) Cathodic protection test after humid and heat resistance test A stainless steel plate (material: SUS304, 1mm thick x 60mm long x 80mm wide) was immersed in 10% hydrochloric acid in a PP tray for 1 minute. After wiping the surface with paper, it was left to stand for 1 week in a constant temperature and humidity chamber at 40°C and 85% humidity to create a test piece with red rust. The prepared test specimens were coated with the cathodic protection coating compositions described in Examples 1-7 and Comparative Examples 1 and 2 on half of each specimen. Next, a zinc plate was placed on the coated surface via a separator. The uncoated end of the test specimen was connected to the cathode of a battery via a lead wire, and the zinc plate was connected to the anode of the battery via a lead wire. A voltage of 6.16V was applied for one day in a constant temperature and humidity chamber at 30°C and 50% humidity, and then the specimens were left to stand for 1000 hours in a constant temperature and humidity chamber at 50°C and 85% humidity. After standing, the coated surface was removed with acetone solvent, and the degree of red rust removal was visually evaluated on the following four-point scale. ◎: Red rust can be restored to black rust and / or iron at a rate of 95% or more relative to the area. ○: Red rust has a recovery rate of 80% or more but less than 95% of the area to black rust and / or iron. △: Red rust has a recovery rate of 60% or more but less than 80% of the area to black rust and / or iron. ×: Red rust has a recovery rate of less than 60% of the area to black rust and / or iron.

[0069] (4) Rust prevention test A stainless steel plate (material: SUS304, 1mm thick x 60mm long x 80mm wide) was polished in accordance with JIS K2246:2018 to create a test specimen. The prepared test specimens were coated with the cathodic protection coating compositions described in Examples 1-7 and Comparative Examples 1 and 2 on half of each specimen. Next, a zinc plate was placed on the coated surface via a separator. The uncoated end of the test specimen was connected to the cathode of a battery via a lead wire, and the zinc plate was connected to the anode of the battery via a lead wire. A voltage of 6.16V was applied for one month in a constant temperature and humidity chamber at 30°C and 50% humidity. After standing, the coated surface was removed with acetone solvent, and the degree of red rust formation was visually evaluated on the following four-point scale. ◎: Red rust is less than 5% of the area. ○: Red rust covers 5% or more but less than 20% of the area. △: Red rust covers 20% to less than 40% of the area. ×: Red rust covers more than 40% of the area.

[0070] As can be seen from the results in Table 1, the composition of the present invention exhibits both an electrochemical corrosion protection effect on SUS plates that have developed red rust and an effect as a rust inhibitor. [Industrial applicability]

[0071] The electrochemical corrosion protection coating composition of the present invention functions not only as an electrochemical corrosion protection paint but also as a corrosion protection paint. Furthermore, because it contains an ionic polymer, it has high conductivity and can be used not only as a chemical polishing agent but also as an electrolytic polishing agent. It is also useful as a rust inhibitor and as a primer after various polishing processes.

Claims

1. A cathodic protection coating composition (Y) comprising an ionic polymer (X) having a cationic functional group (B) and a pH of 5 to 9 at 25°C.

2. The cathodic protection coating composition (Y) according to claim 1, wherein the halogen content of the ionic polymer (X) is 20 ppm or less.

3. The cathodic protection coating composition (Y) according to claim 1, wherein the cationic functional group (B) is a tertiary ammonium cation or a quaternary ammonium cation.

4. The cathodic protection coating composition (Y) according to claim 1, wherein the counterion of the cationic functional group (B) of the ionic polymer (X) is at least one selected from the group consisting of carboxylic acid anions, phosphate anions, and sulfonate anions.

5. An electrochemically protected coating film formed from the electrochemically protected coating composition (Y) according to any one of claims 1 to 4.

6. An electrochemical corrosion protection coating structure in which a conductive coating is laminated on the upper surface of the electrochemical corrosion protection coating according to claim 5.

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