JP7809442B2 - Water-based organic zinc-rich paint composition - Google Patents

Description

The present invention relates to an aqueous organic zinc-rich paint composition.

When zinc-rich paint, which contains a high concentration of zinc dust, is applied to steel and the coating comes into contact with water, the zinc, which has a greater tendency to ionize than iron, becomes the anode, and a protective current flows from the zinc to the iron, protecting the iron from corrosion. This sacrificial protective effect of zinc on iron has long been well known, and zinc-rich paint is often used as a corrosion-protective paint for various steel structures such as road girders, bridges, and plants.

Zinc-rich paints are classified into two types: organic zinc-rich paints and inorganic zinc-rich paints, depending on the type of base resin used as the binder. Organic zinc-rich paints mainly use epoxy resins and amine hardeners as organic binder components, while inorganic zinc-rich paints mainly use alkyl silicate resins as inorganic binders.
The former organic zinc-rich paints are widely used on the market because they have excellent compatibility with the substrate, although they lack corrosion resistance compared to inorganic zinc-rich paints. There are two types of organic zinc-rich paints: those with organic solvent-based dilution media and those with water-based dilution media. However, the performance of the water-based organic zinc-rich paints has not yet reached that of the organic solvent-based organic zinc-rich paints, and there is a growing demand for improvements.

In response to this demand, the applicant proposed in Patent Document 1 an aqueous epoxy resin zinc-rich paint containing an epoxy resin emulsion, a specific amount of zinc powder, and a polyamine compound with a cyclic structure. This zinc-rich paint has good curing properties even when dried at room temperature, and can form a coating film with excellent corrosion resistance.

Furthermore, Patent Document 2 discloses an aqueous anticorrosion coating composition containing an epoxy resin emulsion, an amine resin emulsion, zinc powder, and a phosphate-based rust-preventive pigment, while Patent Document 3 discloses an aqueous organic zinc-rich coating containing an epoxy resin emulsion, a water-soluble polyamine, zinc powder, and a trace amount of silica fine powder.

The aqueous organic zinc-rich paint compositions described in Patent Documents 1 to 3 can form coatings with excellent corrosion resistance at room temperature, but depending on the curing environment during application, the expected corrosion resistance and finish may not be achieved. Furthermore, problems may arise when another corrosion-resistant paint is applied over the zinc-rich coating, leaving room for practical improvement.

Japanese Patent Application Laid-Open No. 2008-272666 Patent No. 5296899 Patent No. 5577475

The present invention aims to provide an aqueous organic zinc-rich paint composition suitable for forming a corrosion-resistant coating film with excellent corrosion resistance, finish, and recoatability.

Zinc dust reacts with water and loses its activity. For this reason, water-based organic zinc-rich paint compositions that use water as a dilution medium are provided to painters in three components - base agent, hardener, and zinc dust - designed to prevent the zinc dust from reacting with water during paint storage. However, it has been discovered that when painters mix these three components on-site and apply the paint, gas is generated even before the water evaporates, and that this gas generation phenomenon causes a significant decrease in various paint film performance characteristics.

The inventors conducted extensive research into methods for suppressing gas generation and discovered that adding a specific amount of anti-rust pigment to an aqueous organic zinc-rich paint composition suppresses gas generation during paint preparation, and that by combining the anti-rust pigment with a specific amount of color pigment and/or extender pigment, a sacrificial anti-corrosion coating film that satisfies all of the following criteria: corrosion prevention, finish, and recoatability.

That is, the present invention provides:
Item 1.
The aqueous organic zinc-rich paint composition contains an epoxy resin emulsion, zinc dust, an anti-rust pigment, a color pigment and/or an extender pigment, a water-dilutable polyamine, a plasticizer, a film-forming aid , and water, and contains 70 mass % or more of zinc dust, 0.5 to 4 mass % of the anti-rust pigment, and 1 to 5 mass % of the color pigment and/or extender pigment in the non-volatile matter of the paint.
Item 2.
Item 2. The aqueous organic zinc-rich paint composition according to item 1, wherein the zinc powder is a combination of zinc powder having an average particle size of 1 to 10 μm and zinc powder having an average particle size of more than 10 but not more than 20 μm.
Item 3.
3. The aqueous organic zinc-rich paint composition according to item 1 or 2, wherein the anti-rust pigment is a pigment capable of eluting phosphate ions or tripolyphosphate ions.
Item 4.
4. The aqueous organic zinc-rich paint composition according to any one of items 1 to 3, wherein the anti-rust pigment is a pigment capable of eluting at least one of calcium ions, magnesium ions and zinc ions.
Item 5.
5. The aqueous organic zinc-rich paint composition according to any one of items 1 to 4, wherein the water-dilutable polyamine is a water-soluble polyamine.
Item 6.
6. The aqueous organic zinc-rich paint composition according to any one of items 1 to 5, wherein the paint is in the form of a two-component, one-powder composition comprising a main component, a curing agent component, and a powder component.
Section 7.
Item 7. A corrosion-protective coating method comprising coating a substrate surface with the aqueous organic zinc-rich coating composition according to any one of Items 1 to 6.
Section 8.
Item 7. A corrosion-protective coating method comprising coating a substrate surface with the aqueous organic zinc-rich coating composition according to any one of Items 1 to 6, and then coating the aqueous coating composition thereon.
Regarding.

The water-based organic zinc-rich paint composition of the present invention can minimize gas generation during paint preparation. Furthermore, the sacrificial corrosion-protective coating film formed using the water-based organic zinc-rich paint composition of the present invention exhibits excellent corrosion protection, finish, and recoatability even when the curing environment fluctuates.

The materials contained in the water-based organic zinc-rich paint composition of the present invention will be explained in order below.

[Epoxy resin emulsion]
The epoxy resin emulsion used in the present invention is prepared by dispersing an epoxy resin in water.

The epoxy resin is a resin having at least two epoxy groups per molecule. The epoxy equivalent of this epoxy resin, calculated based on the nonvolatile content, is preferably 50 to 5,000 g/eq, more preferably 75 to 2,500 g/eq, and even more preferably 80 to 750 g/eq. In this specification, the epoxy equivalent can be determined by the method described in JIS K 7236.

The epoxy resin emulsion is produced by emulsifying the above-mentioned epoxy resin using a conventional forced emulsification method. Examples of emulsifiers used here include compounds containing polyoxyalkylene units in the molecule, such as nonionic polyoxyalkylene compounds, anionic polyoxyalkylene compounds, and adducts of these compounds with epoxy resins and diisocyanate compounds. These are preferably used alone or in blends.

Commercially available epoxy resin emulsions produced using this method include Epolsion EA 1, 2, 3, 7, 12, 20, 55, and HD2 (trade names, manufactured by Nippon NSC Co., Ltd.); Aquatote 205, 510, 3520, 3540, 35201, 5003, and 5520 (trade names, manufactured by Toto Resin Chemical Co., Ltd.); Yukaresin KE-002, KE-116, E-1022, and KE-301C (trade names, manufactured by Yoshimura Oil Chemical Co., Ltd.); and Modepics 301, 302, 303, 304, and EM-101-50 (trade names, manufactured by Asahi Denka Kogyo Co., Ltd.).

[Zinc powder]
As the zinc powder, those normally used in zinc-rich paints can be used.

In the present invention, the zinc dust content in the non-volatile matter of the paint is 70% by mass or more, preferably 75 to 95% by mass, and more preferably 80 to 88% by mass, from the viewpoint of the corrosion resistance and finish of the paint film.

From the viewpoints of sacrificial anticorrosion action, the amount of gas generated during paint preparation, and recoating suitability, it is preferable that the zinc powder be a combination of zinc powder having an average particle size of 1 to 10 μm and zinc powder having an average particle size of more than 10 but not more than 20 μm.
Here, the average particle size of zinc dust is the average particle size on a volume basis, and refers to the particle size at the point where the cumulative volume is 50% when the total volume of zinc dust is taken as 100% based on the particle size distribution of zinc dust in a dispersion liquid. The average particle size can be measured using a particle size distribution measuring device using a laser diffraction/scattering method.

When using a combination of small particle zinc powder with an average particle size of 1 to 10 μm and large particle zinc powder with an average particle size of more than 10 but not exceeding 20 μm, the mass ratio of small particle zinc powder to large particle zinc powder should be in the range of 10/90 to 95/5, particularly 55/45 to 90/10.

[Anti-rust pigment]
The aqueous organic zinc-rich paint composition of the present invention contains 0.5 to 4 mass % of the rust-preventive pigment in the nonvolatile matter of the paint, and more preferably 0.8 to 3.5 mass %.

The inclusion of an anti-rust pigment suppresses gas generation during paint preparation and helps form a coating film that exhibits stable sacrificial corrosion protection, excellent finish, and recoatability, even when curing conditions fluctuate. Anti-rust pigments known in the paint industry can be used, but pigments that are capable of eluting at least one ion selected from calcium ions, magnesium ions, zinc ions, aluminum ions, silicate ions, phosphate ions, and tripolyphosphate ions in a corrosive environment are particularly preferred.

In the present invention, the presence or absence of ion elution from the anti-rust pigment can be determined, for example, by dissolving the anti-rust pigment in an aqueous sodium chloride solution and measuring the amount of elution using ICP atomic emission spectroscopy. More specifically, one method involves adding 10% by mass of anti-rust pigment to a 5% by mass aqueous sodium chloride solution, stirring at 25°C for 6 hours, leaving it to stand for 24 hours, removing the precipitate, and then measuring the supernatant using ICP atomic emission spectroscopy to detect the presence or absence of dissolved elements.

Specific examples of the above-mentioned anti-rust pigments include, without limitation, single compounds, composite compounds, compositions using multiple compounds, etc., as long as they are capable of eluting the above-mentioned ions. Specific examples include phosphate-based metal compounds such as zinc phosphate, magnesium phosphate, magnesium ammonium phosphate co-eutectoid, magnesium monohydrogen phosphate, magnesium dihydrogen phosphate, magnesium calcium phosphate co-eutectoid, magnesium phosphate co-eutectoid, magnesium phosphate co-eutectoid, magnesium nickel phosphate co-eutectoid, calcium phosphate, calcium ammonium phosphate, calcium monohydrogen phosphate, calcium dihydrogen phosphate, calcium fluoride phosphate chloride, aluminum phosphate, and aluminum hydrogen phosphate; phosphate-based metal compounds such as magnesium phosphite, calcium phosphite, magnesium calcium phosphite co-eutectoid, basic zinc phosphite, barium phosphite, manganese phosphite, and calcium hypophosphite; calcium silicate, zinc silicate, aluminum silicate, aluminum orthosilicate, and hydrated aluminum silicate; Examples of suitable silicates include metal silicates such as aluminosilicates, borosilicates, beryllosilicates, aluminum calcium silicate, aluminum sodium silicate, aluminum beryllium silicate, sodium silicate, calcium orthosilicate, calcium metasilicate, calcium sodium silicate, zirconium silicate, magnesium orthosilicate, magnesium metasilicate, magnesium-calcium silicate, manganese silicate, and barium silicate; metal ion-exchanged silica compounds such as magnesium ion-exchanged silica and calcium ion-exchanged silica; tripolyphosphate-based metal compounds such as aluminum dihydrogen tripolyphosphate, magnesium tripolyphosphate, aluminum tripolyphosphate, and zinc dihydrogen tripolyphosphate; molybdate-based metal compounds such as aluminum molybdate, calcium molybdate, and aluminum phosphomolybdate; composite oxides of iron oxide and magnesium oxide, composite oxides of iron oxide and calcium oxide, zinc oxide, and zinc compounds of iron oxide and zinc oxide. As mentioned above, these may be used alone or in combination of two or more, or may be combined to form a composite of two or more. Additionally, modified or treated products of these exemplified compounds with silica, calcium silicate, and other silicic acid compounds, or magnesium oxide, are also included in the anti-rust pigments.

Commercially available anti-rust pigments can be used alone or in combination. Examples of such commercially available products include "EXPERT NP-1000", "EXPERT NP-1020C", "EXPERT NP-1100", and "EXPERT NP-1102" (all trade names, manufactured by Toho Pigment Industry Co., Ltd.), "LF BOSEI CP-Z", "LF BOSEI MZP-500", "LF BOSEI CRFC-1", "LF BOSEI M-PSN", "LF BOSEI MC-400WR", "LF BOSEI PM-300", and "LF BOSEI PM-308" (all trade names, manufactured by Kikuchi Color Co., Ltd.), "K-WHITE 140", "K-WHITE Ca650", "K-WHITE 450H", "K-WHITE G-105", "K-WHITE #105", and "K-WHITE #82," "K-WHITE G102S" (all product names manufactured by Teika Corporation), "SHIELDEX C303," "SHIELDEX AC-3," "SHIELDEX C-5" (all manufactured by W.R. Grace & Co.), "Silomask 52," "Silomask 52M," "Silomask 22MR-H" (manufactured by Fuji Silysia), and "Novinox ACE-110" (manufactured by SNCZ, France) are examples of such products.

In the present invention, it is preferable to use an anti-rust pigment capable of eluting phosphate ions or tripolyphosphate ions and/or a pigment capable of eluting at least one of calcium ions, magnesium ions, and zinc ions, as these are excellent at suppressing gas generation during paint preparation.

[Color pigment and/or extender pigment]
The aqueous organic zinc-rich paint composition of the present invention contains 1 to 5% by mass of color pigment and/or extender pigment in the nonvolatile matter of the paint, and more preferably 2 to 4% by mass.

By including color pigments and/or extender pigments, sacrificial corrosion protection is maintained while achieving a stable finish even when curing conditions fluctuate.

Coloring pigments include titanium oxide, red iron oxide, yellow iron oxide, and carbon black, while extender pigments include talc, silica, calcium carbonate, mica, kaolin, barium sulfate, and zinc oxide (zinc oxide). These can be used alone or in combination of two or more.

[Plasticizer and/or film-forming aid]
The aqueous organic zinc-rich paint composition of the present invention contains a plasticizer and/or a film-forming aid as necessary, since it can provide a coating film with a stable finish even if the curing environment changes.
The plasticizer is a compound that remains in the coating film and is liquid at room temperature, and any plasticizer known in the coating field can be used. Specific examples of the plasticizer include fatty acid ester plasticizers, phosphate ester plasticizers, and epoxy plasticizers.

Fatty acid ester plasticizers include dimethyl adipate, dibutyl adipate, diisobutyl adipate, dihexyl adipate, di-2-ethylhexyl adipate, diisononyl adipate, dioctyl adipate, dibutyl diglycol adipate, diisononyl cyclohexane dicarboxylate, dimethyl cyclohexane dicarboxylate, diethyl cyclohexane dicarboxylate, di-2-ethylhexyl cyclohexane dicarboxylate, DBE (dibasic acid ester), etc.

Examples of phosphate ester plasticizers include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, tricyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, dimethyl ethyl phosphate, methyl dibutyl phosphate, ethyl dipropyl phosphate, isodecyl diphenyl phosphate, hydroxyphenyl diphenyl phosphate, resorcinol bisdiphenyl phosphate, triarylisopropyl phosphates, compounds modified with various substituents, and various condensation types of these phosphate ester plasticizers.

Examples of epoxy plasticizers include epoxidized unsaturated fats and oils, epoxidized unsaturated fatty acid esters, alicyclic epoxy compounds, epichlorohydrin derivatives, and mixtures thereof. Specific examples include epoxidized soybean oil, epoxidized linseed oil, 4,5-epoxycyclohexane-1,2-dicarboxylate di-2-ethylhexyl, epoxy octyl stearate, and epoxy butyl stearate.

When a plasticizer is used, its content should be within the range of 0.1 to 1% by mass, preferably 0.15 to 0.7% by mass, of the non-volatile content of the paint.

On the other hand, coalescents are high-boiling organic solvents that are compatible with epoxy resins. They remain in the coating film even after the water has evaporated, and gradually volatilize while promoting the fusion of epoxy resin particles. Specific examples of coalescents include ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, ethylene glycol monohexyl ether, ethylene glycol mono-2-ethylhexyl ether, diethylene glycol monomethyl ether, diethylene glycol diethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, diethylene glycol monophenyl ether, diethylene glycol monohexyl ether, diethylene glycol monobenzyl ether, and diethylene glycol mono-2-ethylhexyl ether. Examples of suitable glycol ether compounds include triethylene glycol monomethyl ether, triethylene glycol monobutyl ether, polyethylene glycol monobutyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol monophenyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monobutyl ether; and ester compounds such as 2,2,4-trimethylpentanediol monoisobutyrate and 2,2,4-trimethylpentanediol diisobutyrate.

When a film-forming aid is used, its content should be in the range of 0.4 to 2.0 mass%, preferably 0.5 to 1.8 mass%, based on the non-volatile content of the paint.

[Water-dilutable polyamines]
In the aqueous organic zinc-rich paint composition of the present invention, the water-dilutable polyamine which is the reaction partner of the epoxy resin emulsion is a water-soluble or water-dispersible resin having at least two amino groups in one molecule.

In this specification, a water-soluble resin is a resin that dissolves in water and whose aqueous resin solution appears transparent to the naked eye, while a water-dispersible resin is a resin that is dispersed in water and whose aqueous resin dispersion appears cloudy to the naked eye.

The polyamine can be selected from aliphatic polyamines such as ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, triaminopropane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, isophoronediamine, and 1,3-bisaminomethylcyclohexane; aromatic polyamines such as phenylenediamine, metaxylylenediamine, paraxylylenediamine, and diaminodiphenylmethane; polyamine compounds such as polyoxyethylenediamine, polyoxypropylenediamine, triethyleneglycoldiamine, and tripropyleneglycoldiamine; and modified polyamine resins obtained by modifying such polyamine compounds using known methods. Examples of modifications include amidation, Mannich reaction, and epoxy adduct formation.

Such water-dilutable polyamines are commercially available. Specific examples of such water-soluble polyamines include "TOMAID TXH-674-B," "TOMAID TXH-685-A," "TOMAID TXS-53-C," "TOMAID TXH-694," "FUJICURE FXI-919," "FUJICURE FXH-927," and "FUJICURE FXH-935" (all trade names, manufactured by T&K TOKA Corporation), "EPIKURE8537-WY-60" (trade name, manufactured by MOMENTIVE Corporation), "SANMAID WH-910" (trade name, manufactured by Air Products Japan Co., Ltd.), "DAITOCHLOR I-5986," "DAITOCHLOR I-6020," and "DAITOCHLOR X-5663H" (all trade names, manufactured by Daito Sangyo Co., Ltd.), and examples of such water-dispersible polyamines include "FUJICURE FXS-918-FA" (trade name, manufactured by T&K TOKA Corporation). (manufactured by TOKA Corporation) etc.

The amount of water-dilutable polyamine used should be within the range of 0.3 to 1.2 equivalents of active hydrogen per equivalent of epoxy groups in the epoxy resin emulsion, more preferably 0.4 to 1.0 equivalents, from the perspectives of the sacrificial corrosion protection, finish, and coating workability of the coating film.

[Water-based organic zinc-rich paint composition]
The aqueous organic zinc-rich paint composition of the present invention is a composition comprising an epoxy resin emulsion, zinc dust, an anti-rust pigment, a coloring pigment and/or an extender pigment, a water-dilutable polyamine, and water.

The aqueous organic zinc-rich paint composition may optionally contain modifying resins such as alkyd resins and urethane resins; and conventional paint additives such as dispersants, surface conditioners, defoamers, preservatives, neutralizing agents, flash rust inhibitors, and thickeners.

The paint form during storage can be changed as needed, but a two-component, one-powder composition consisting of a base component, a hardener component, and a powder component is preferred. More specifically, a three-component composition consisting of a base component containing an epoxy resin emulsion, a hardener component containing a water-dilutable polyamine, and a powder component containing zinc dust, with color pigment, extender pigment, rust-preventive pigment, and water added to any of the above components, is suitable.

One method for preparing paint for painting is to mix the aforementioned ingredients in a container and stir and mix them using a hand mixer or static mixer.

[Corrosion prevention coating method]
The present invention is a corrosion-protective coating method in which the aqueous organic zinc-rich coating composition is applied to a substrate surface. The substrate surface is usually steel, but non-ferrous metals can also be used. Specific examples of substrates include land structures such as towers, tanks, and plants; water structures such as ships, tankers, and overwater bridges; road structures such as roads, bridges, and tunnels; architectural structures such as houses and buildings; and outdoor equipment such as guard fences and industrial machinery. These substrates may have a previous coating film already applied to them.

The aqueous organic zinc-rich paint composition is applied to the substrate surface so that the dry film thickness is typically within the range of 10 to 200 μm, preferably 15 to 150 μm. The application can be carried out by known application methods, such as air spraying, airless spraying, brush application, or roller application. The coating can be dried at room temperature, but forced drying or heat drying can also be used if necessary.

The aqueous organic zinc-rich paint composition exhibits sacrificial corrosion protection against iron substrates and can therefore be used as a primary rust-preventive primer or anti-corrosion base. When used as a anti-corrosion base, the aqueous organic zinc-rich paint composition of the present invention is applied to the substrate surface to form a coating, and then an anti-corrosion primer is applied on top of that, followed by a top coat with excellent weather resistance, thereby maintaining corrosion protection for a long period of time.

Examples of primer paints include epoxy resin-based primer paints, modified epoxy resin-based primer paints, and urethane resin-based primer paints. Examples of topcoat paints include acrylic resin-based topcoat paints, urethane resin-based topcoat paints, silicone resin-based topcoat paints, and fluororesin-based topcoat paints. The water-based organic zinc-rich paint composition forms a coating film with excellent recoatability and sacrificial corrosion protection, and therefore can exhibit long-term corrosion protection even when the primer paint and topcoat paint applied on top are water-based paint compositions diluted with water.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples.

<Production of Water-Based Organic Zinc-Rich Paint Composition>
Example 1
In a container, 200 parts of "ADEKA RESIN EM101-50" (Note 1), 20 parts of "K-WHITE #105" (Note 2), 30 parts of talc, and 1.5 parts of "DISPER BYK-190" (Note 5) were blended and mixed by stirring, and then "SANSO CIZER E-PS" (Note 6), 5.0 parts of 2,2,4-trimethylpentanediol monoisobutyrate, 10 parts of propylene glycol monobutyl ether, 0.1 parts of ammonia water, and 60 parts of clean water were blended and mixed by stirring to obtain a liquid main component.
In a separate container, 27 parts of "Fujicure FXH-935" (Note 8) and 30 parts of clean water were blended and mixed with stirring to obtain a liquid curing agent component.
In a separate container, zinc powder having an average particle size of 4 μm and zinc powder having an average particle size of 15 μm were blended and mixed to obtain a powder component.

The curing agent component and powder component were mixed into the container containing the main component, and the mixture was stirred and mixed until uniform to produce the aqueous organic zinc-rich paint composition (A-1).

Examples 2 to 18 and Comparative Examples 1 to 5
Water-based organic zinc-rich coating compositions (A-2) to (A-23) were produced in the same manner as in Example 1, except that the materials and blending amounts used are shown in Tables 1-1 and 1-2 below. The resulting water-based organic zinc-rich coating compositions were evaluated as follows.

(Note 1) "ADEKA RESIN EM101-50": Trade name, manufactured by ADEKA CORPORATION, emulsion obtained by dispersing bisphenol A type epoxy resin in water with polyethylene glycol-modified bisphenol A type epoxy resin containing a nonionic hydrophilic component as the dispersion stabilizing resin, epoxy equivalent per nonvolatile content: 495 to 575 g/eq, nonvolatile content 50% by mass,
(Note 2) "K-WHITE 105": Trade name, manufactured by Teika Corporation, aluminum dihydrogen tripolyphosphate and zinc oxide mixture,
(Note 3) "K-WHITEG102S": Trade name, manufactured by Teika Co., Ltd., magnesium oxide-treated aluminum dihydrogen triphosphate,
(Note 4) "Silomask 52": Product name, manufactured by Fuji Silysia Chemical Ltd., calcium-based ion-exchange silica,
(Note 5) "Silomask 22MR-H": Product name, manufactured by Fuji Silysia Chemical Ltd., magnesium-based ion-exchange silica,
(Note 6) "DIPER BYK-190": Product name, manufactured by BYK, pigment dispersant,
(Note 7) "Sansocizer E-PS": Trade name, trade name, manufactured by New Japan Chemical Co., Ltd., 4,5-epoxycyclohexane-1,2-dicarboxylic acid di-2-ethylhexyl,
(Note 8) "Fujicure FXH-935": Trade name, manufactured by T&K TOKA Corporation, resin non-volatile content 80%, active hydrogen equivalent 170 g/eq, metaxylylenediamine modified polyaminoamide type, water-soluble polyamine resin,
(Note 9) "Fujicure FXS-918-FA": Trade name, manufactured by T&K Toka Corporation, non-volatile content 60%, active hydrogen equivalent 145 g/eq, modified aliphatic polyamine resin emulsion.

<Evaluation test>
(*) Salt spray resistance test:
Each of the aqueous organic zinc-rich coating compositions (A-1) to (A-23) obtained in the Examples and Comparative Examples was applied to a steel plate so that the dry film thickness was 75 μm, and the plate was dried at 23° C. for one week to prepare a test specimen. In accordance with JIS K5600-7-1, which specifies neutral salt spray resistance, the test specimens were exposed to salt spray for 1,440 hours, and the degree of rust and blisters that occurred on the cut and painted surfaces was evaluated based on the following criteria.
◎: No rust or blisters on the cut or painted surface.
○: Rust width of cut part is 0 mm, there is slight rust or blisters on the painted surface,
△: Rust width of cut part is 1 mm or less, rust or blisters are found on the painted surface,
×: Rust width at cut part exceeds 1 mm, rust or blisters occur on the painted surface.

(*)water resistance:
Each of the aqueous organic zinc-rich coating compositions (A-1) to (A-23) obtained in the Examples and Comparative Examples was applied to a steel plate so that the dry film thickness was 75 μm, and the resulting plate was dried at 23°C for 1 week to prepare a test specimen. This test specimen was immersed in deionized water at 23°C for 240 hours, and then visually evaluated for appearance.
◎: No change at all,
〇: Some discoloration is observed, but no coating defects are observed.
△: Either obvious discoloration or coating defects are observed.
×: Both obvious discoloration and coating defects are observed.
(*) Hydrogen gas generation suppression:
Immediately after mixing the main component, hardener component, and powder component, each aqueous organic zinc-rich paint composition was placed in a test tube and the liquid level rise (mm) after one day at 20°C was measured. The lower the value, the better.
(*) Finish Each water-based organic zinc-rich coating composition was applied to a steel plate using a diaphragm-type airless coating device to a thick coating thickness of 300 μm, and the appearance was evaluated visually.
◎: No sagging or dripping at all,
〇: Very little sagging or dripping is observed.
△: Sagging and dripping are observed.
×: Sagging and sagging are significantly observed.

(*) Suitability for overcoating with primer:
Each aqueous organic zinc-rich coating composition was applied to a steel plate to a dry film thickness of 75 μm, allowed to dry for one day, and then a water-based anticorrosive primer coating "Water-based Epotect Primer" manufactured by Kansai Paint Co., Ltd. was applied thereon to a dry film thickness of 60 μm, allowed to dry for one day under high temperature and high humidity conditions of 35°C and 95%, and the appearance was evaluated visually.
◎: No blistering of the primer coating film.
◯: Very slight swelling is observed in the primer coating film.
△: Blisters are observed in the primer coating film.
×: Significant swelling is observed in the coating film of the primer paint.

Claims (8)

The coating composition comprises an epoxy resin emulsion, zinc powder, an anti-rust pigment, a color pigment and/or an extender pigment, a water-dilutable polyamine, a plasticizer, a film-forming aid, and water, and the coating composition contains 70% by mass or more of zinc powder, 0.5 to 4% by mass of the anti-rust pigment, and 1 to 5% by mass of the color pigment and/or the extender pigment in the non-volatile matter of the coating composition,
the plasticizer comprises di-2-ethylhexyl 4,5-epoxycyclohexane-1,2-dicarboxylate;
The coalescent includes a glycol ether compound, 2,2,4-trimethylpentanediol monoisobutyrate, or 2,2,4-trimethylpentanediol diisobutyrate.
A water-based organic zinc-rich paint composition. The aqueous organic zinc-rich paint composition according to claim 1, wherein the zinc powder is a combination of zinc powder having an average particle size of 1 to 10 μm and zinc powder having an average particle size of more than 10 but not more than 20 μm. The aqueous organic zinc-rich paint composition according to claim 1 or 2, wherein the anti-rust pigment is a pigment capable of eluting phosphate ions or tripolyphosphate ions. The water-based organic zinc-rich paint composition according to any one of claims 1 to 3, wherein the anti-rust pigment is a pigment capable of eluting at least one of calcium ions, magnesium ions, and zinc ions. The aqueous organic zinc-rich paint composition according to any one of claims 1 to 4, wherein the water-dilutable polyamine is a water-soluble polyamine. The aqueous organic zinc-rich paint composition according to any one of claims 1 to 5, wherein the paint is in the form of a two-component, one-powder composition composed of a base component, a curing agent component, and a powder component. A corrosion-protective coating method comprising applying the aqueous organic zinc-rich coating composition described in any one of claims 1 to 6 to a substrate surface. A corrosion-protective coating method comprising applying the aqueous organic zinc-rich coating composition described in any one of claims 1 to 6 to a substrate surface, and then applying an aqueous coating composition thereon.