JP3227168B2 - Water-based rust preventive paint composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous rust-preventive coating composition for forming a coating for the purpose of preventing rust of various metal products such as iron, zinc, aluminum and magnesium.

[0002]

2. Description of the Related Art Conventionally, a method of spraying or dipping an alkyd resin-based or melamine-alkyd resin-based aqueous paint for the purpose of preventing rust of various metal materials (including plated steel sheets) including iron, or anion. Alternatively, a method of electrodepositing a cationic electrodeposition paint or the like is used.

However, in the case of alkyd resin-based or melamine-alkyd resin-based paints, it is often impossible to satisfy the recent demand for high rust-preventive performance. have.

[0004] In contrast, in the case of electrodeposition paints, although excellent rust prevention is obtained, a large amount of energy is required for the baking process, and the end portions of the base material to be coated and the convex portions of the uneven surface are required. It has drawbacks such as the film thickness becoming thinner due to the flow during baking, resulting in poor rust prevention.

[0005] On the other hand, recently, a coating film of a vinylidene chloride copolymer has been reported to have excellent denseness, and furthermore, excellent ability to block moisture and oxygen from passing through the coating film (hereinafter referred to as barrier property). Utilizing the properties, an aqueous rust preventive paint using a vinylidene chloride copolymer latex containing a complexing agent has been proposed (JP-A-63-105073,
JP-A-1-198669).

[0006]

However, when a paint composition using such a vinylidene chloride copolymer latex was also subjected to a salt spray test, even though the rust prevention of the cross cut portion was sufficient, it was found that the other portions did not. It has drawbacks such as blistering and poor adhesion, especially when applied to galvanized steel sheets.

Accordingly, an object of the present invention is to provide a water-based rust-preventive coating composition having extremely excellent rust-preventing power when applied to various metal product bases such as iron, zinc, aluminum, magnesium and galvanized steel. It is in.

[0008]

SUMMARY OF THE INVENTION The present invention provides a latex (A) of a vinylidene chloride polymer or a copolymer of vinylidene chloride and a vinyl group-containing monomer copolymerizable therewith, and which can be dissolved or dispersed in water. An epoxy resin (B) and a complexing agent (C) which is a compound having a functional group capable of forming a complex compound with a metal ion, wherein the solid content of (A) is a salt
30-65 parts by weight of vinylidene chloride content, solid of (B)
1 to 30 parts by weight, solid content of (C) 5 to 40 parts by weight
The water-based rust-preventive paint composition is characterized in that:

The present inventors have applied the above-mentioned latex (A), epoxy resin (B) and complexing agent (C) in a fixed ratio as described above to paint various metal product bases as described above . In this case, an aqueous rust-preventive coating composition exhibiting extremely excellent rust-preventing power was obtained, and the present invention was completed.

[0010] The latex (A) used in the present invention.
Is emulsion polymerization of a vinylidene chloride monomer or a mixture of a vinylidene chloride monomer and a vinyl group-containing monomer copolymerizable therewith by a known method, for example, using a polymerization initiator in the presence of an emulsifier. It is obtained by doing.

As the emulsifier and polymerization initiator used here, those conventionally used can be used. However, a nonionic emulsifier is used as an emulsifier in terms of the performance of a coating film obtained by using the aqueous rust preventive coating composition of the present invention. Among them, a reactive nonionic emulsifier having a vinyl group copolymerizable with vinylidene chloride in its molecule is particularly preferable.

The latex (A) generally has a nonvolatile content, that is, a resin solid content of 40 to 6 parts by weight in 100 parts by weight of the latex.
It is preferable to use 0 parts by weight, and the remaining 60 to 40 parts by weight can be composed of water or a mixed solution of water and a small amount of a water-soluble organic solvent such as alcohols, cellosolves, carbitols and ethers.

The vinylidene chloride polymer or copolymer in the latex (A) has a particle size of 50 nm to 200 nm, which is preferred because of its stability, good coating workability, and the like.

When a vinylidene chloride copolymer is used in the latex (A), examples of the vinyl group-containing monomer copolymerizable with vinylidene chloride include methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) Esters of (meth) acrylic acid such as propyl acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, and glycidyl (meth) acrylate; ) Acrylic acid and one or a mixture of two or more vinyl compounds such as vinyl chloride, vinyl acetate, styrene, acrylonitrile, vinyl toluene, vinyl fluoride, vinylidene fluoride and the like can be used.

In the latex (A) of the present invention, a polymer of vinylidene chloride alone can be used, but a copolymer of vinylidene chloride and the above-mentioned vinyl group-containing monomer copolymerizable with vinylidene chloride is used. In this case, the content of vinylidene chloride in the copolymer is preferably at least 30% by weight, particularly preferably at least 50% by weight.

When the content of vinylidene chloride in the vinylidene chloride copolymer is less than 30% by weight, the crystallinity of the vinylidene chloride copolymer becomes low, and the barrier property of the formed coating film becomes poor. Not preferred.

Conventionally, when a latex containing a vinylidene chloride polymer or a vinylidene chloride copolymer containing about 95% by weight or more of vinylidene chloride is used, a crystal of the vinylidene chloride polymer or the copolymer in a coating film to be formed is used. This has the drawback that the degree of adhesion is too high and the adhesion to the substrate is poor.

However, in the coating composition according to the present invention, 95% of vinylidene chloride can be obtained by using the epoxy resin of the component (B) and the complexing agent of the component (C) in combination.
It has been found that, of course, a copolymer containing only vinylidene chloride can be used as well as a copolymer containing not less than weight%.

The epoxy resin (B) which can be dissolved or dispersed in water used in the coating composition of the present invention is diglycidyl ether of polyalkylene oxide or diglycidyl ether of polyalkylene oxide adduct to polyphenol, or polyglycol. The reaction product of a polyglycidyl ether of phenol and a secondary amine can be used.

The diglycidyl ether of polyalkylene oxide which can be used includes, for example, diglycidyl ether of polyethylene oxide and diglycidyl ether of polypropylene oxide.

The diglycidyl ether of a polyalkylene oxide adduct to polyphenol is, for example, 2,2.
Diglycidyl ether of a polyethylene oxide adduct to bis (4-hydroxyphenyl) -propane,
Diglycidyl ether of 2,2-bis (4-hydroxyphenyl) -propane adduct of polypropylene oxide, 2,2-bis (4-hydroxycyclohexane)
-Diglycidyl ether of a polypropylene oxide adduct to propane.

These epoxy resins having a polyalkylene oxide in the skeleton have a strong hydrophilicity and can be dispersed in water by themselves. However, the water resistance and rust prevention of the coating film formed by the coating composition of the present invention can be improved. From the viewpoint of properties, the larger the molecular weight is, the more preferable, and those having a molecular weight of usually 800 to 5,000 are particularly preferable.

The polyglycidyl ether of the polyphenol is generally produced, for example, by etherification of epichlorohydrin or dichlorohydrin with polyphenol in the presence of an alkali. Examples of polyphenols include 2,2-bis (4-hydroxyphenyl) -propane, 4,4'-dihydroxybenzophenone, 1,1
-Bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -isobutane, 2,2-
Bis (4-hydroxy-t-butylphenyl) -propane, bis (2-hydroxynaphthyl) methane and the like can be mentioned. Since such an epoxy resin alone does not have hydrophilicity, it is necessary to impart hydrophilicity by reacting with an amine. As the amine that can be used, any of primary amine, secondary amine and tertiary amine can be used, but secondary amine is particularly preferable, and these reaction products are neutralized with an inorganic acid or an organic acid to make them hydrophilic. Good to do.

Examples of the secondary amine include aliphatic or cycloaliphatic amines such as diethylamine, dipropylamine, dibutylamine, ethylpropylamine, and alkanolamines such as methylethanolamine, ethylethanolamine, methylisopropanolamine, and diethanolamine. , Diisopropanolamine, and cyclic amines such as pyrrolidine, piperidine, and morpholin, which can be used in a mixture of two or more.

The polyglycidyl ether of polyphenol and the secondary amine have an equivalent ratio of glycidyl group to amine of 1/1.
Or more, i.e., no solvent or in the presence of a suitable solvent such as alcohol, cellosolve, ketone, toluene, xylene, etc.
The reaction is performed at a temperature of 0 to 120 ° C. to obtain an amine-modified epoxy resin. The amine-modified epoxy resin preferably has an amino group content of 0.3 mol to 2 mol per 1 kg of the solid content.

Examples of the acid for neutralizing the resin which is a reaction product of the polyglycidyl ether of polyphenol and the secondary amine include organic acids such as formic acid, acetic acid, propionic acid and lactic acid, or hydrochloric acid, sulfuric acid, nitric acid and phosphorus. Inorganic acids such as acids can be used, and after neutralization with these acids, the resin is dispersed in water and used.

The complexing agent (C) which is a compound having a functional group capable of forming a complex compound with a metal ion used in the coating composition of the present invention includes, for example, mercaptopropionic acid and neopentyl glycol, trimethylolpropane or Thiol group-containing compounds such as esters with alcohols such as pentaerythritol, tannic acid, gallic acid, pyrogallol, phenolic hydroxyl-containing compounds such as catechol, and phosphoric acid-containing compounds such as phytic acid, and the like. It can be used in the form of one or more mixtures.

The above-mentioned complexing agent (C) may be used as it is or after being dissolved in a water-soluble solvent such as alcohol and previously dispersed in the latex (A) of the coating composition of the present invention, or The above-mentioned epoxy resin (B) dispersible in water may be partially or wholly reacted and used in a state of being bonded to the epoxy resin skeleton. The latter method is preferred because after coating film formation, the adhesion between the object and the coating film is excellent.
At this time, an epoxy group in the epoxy resin and a functional group capable of reacting with the epoxy group in the complexing agent, for example, a thiol group,
The desired compound is obtained by reacting with a phenolic hydroxyl group, a phosphoric acid group, a carboxyl group (for example, contained in gallic acid) and the like.

The method of such a reaction is as follows: epoxy resin (B)
Is reacted with a functional group capable of reacting with the above-mentioned epoxy group of the complexing agent (C), for example, a thiol group, a phenolic hydroxyl group, a carboxyl group, a phosphoric acid group, etc., and maintains a complex compound forming ability. For this reason, in order to prevent gelation during the reaction, the number of the above functional groups may be set to be excessive with respect to the number of the epoxy groups. The reaction is usually carried out at a reaction temperature of 40 to 120 ° C. without a solvent or, if necessary, in an organic solvent such as alcohols, esters, ethers and ketones. When modifying with the amine, it is preferable to add these complexing agents and react at the same time, since gelation during the reaction can be prevented.

The aqueous rust preventive coating composition according to the present invention comprises the above-mentioned vinylidene chloride polymer or vinylidene chloride copolymer latex (A), the above-mentioned epoxy resin (B) and the above-mentioned complexing agent (C) in water. To obtain a stable emulsion.

At this time, if necessary, a coloring pigment, a rust-preventive pigment, an extender, a curing agent such as a melamine or a blocked isocyanate compound, and other various additives usually used in paints, for example, a plasticizer, a surfactant, and a wetting agent. An agent or the like and an organic solvent may be added.

In the water-based rust preventive coating composition of the present invention, the solid content of the component (A) is 30 to 65 parts by weight in terms of the vinylidene chloride content contained therein, and the solid content of the component (B) is 1%.
It is used so that the solid content of the component (C) is 5 to 40 parts by weight.

When the content of vinylidene chloride in the solid content of the component (A) is less than 30 parts by weight, the barrier properties of the coating film derived from vinylidene chloride cannot be sufficiently obtained, and as a result, the rust-preventive effect is poor. Is not preferred. Also 65
If the amount is more than 10 parts by weight, the formed coating film is too hard, and when heat is applied, vinylidene chloride is decomposed, the release amount of hydrochloric acid is increased, and the heat resistance of the coating film is deteriorated.

The solid content of the component (B) is 1 to 30 parts by weight, preferably 5 to 25 parts by weight, as the solid content of the epoxy resin excluding the amine and complexing agent when reacted. If the amount is less than 1 part by weight, the adhesion of the formed coating film to the metal substrate to be coated is undesirably deteriorated. On the other hand, if the amount exceeds 30 parts by weight, the crystallinity of the vinylidene chloride polymer or copolymer of the above-mentioned component (A) is reduced, which deteriorates the barrier properties of the coating film and the rust preventive power.

When a part or the whole of the solid content of the complexing agent of the component (C) is bonded to the epoxy resin as described above, the solid content of the complexing agent is 5 to 5 including the complexing agent. 4
0 parts by weight, preferably 10 to 30 parts by weight are used. When the amount is less than 5 parts by weight, the amount of the complex compound with the metal to be coated is insufficient, and the adhesion and rust prevention of the formed coating film are unfavorably deteriorated. If it exceeds 40 parts by weight, it is difficult to obtain a uniform coating film, and when a rust prevention test is performed, blisters and spot-like rust may be generated on the coating film, which is not preferable.

The water-based anticorrosive coating composition of the present invention can be applied by brushing, spray coating, dip coating, or electrodeposition coating.
At a temperature of about 100 ° C. for about 5 to about 40 minutes, preferably 10 to
Dry for 30 minutes to obtain a cured film.

At the time of coating, the viscosity may be adjusted by diluting with water or adding a thickener in order to obtain a coating viscosity suitable for each coating method.

When dip coating is used, room temperature to about 60
The coated object is immersed in a coating liquid at 5 ° C. for 5 seconds to 3 minutes, preferably for 10 seconds to 60 seconds, and after a coating film is applied, room temperature to about 40 ° C.
At 1 to 40 minutes, preferably 2 to 10 minutes, and then dried as described above.

In performing the electrodeposition coating, an electric conductor (preferably a stainless steel plate, a platinum plate or a carbon rod can be used) is immersed in opposition to the object to be coated, and a DC voltage is applied using these as electrodes. By doing so, electrodeposition coating can be performed. At this time, if the object to be coated is a cathode, the vicinity of the surface of the object to be coated becomes a reducing environment, the stabilization of the emulsion particles is destroyed, and aggregation and precipitation occur to form a coating film.
Conversely, when the object to be coated is an anode, the metal to be coated is eluted into the coating, and the complexing reaction proceeds on the surface of the coating, causing the bonding of the coating particles and the formation of a deposited coating. Is done.

The applied voltage at the time of electrodeposition coating is usually 1 to 500
V, preferably 10 to 300 V, and the time is usually 1 second to 5
Minutes, preferably 20 seconds to 3 minutes.

[0041]

When the water-based rust-preventive coating composition of the present invention is applied to various metallic coatings as described above, the denseness of the coating film is obtained due to the crystallinity of the vinylidene chloride polymer or the vinylidene chloride copolymer. As a result, in addition to obtaining high barrier properties, good adhesion to the substrate to be coated is obtained due to the hydroxyl group and other polar groups of the epoxy resin. Further, since the coating composition according to the present invention contains a complexing agent, a complex bond is formed between the coating film and the metal to be coated, so that an extremely strong adhesive force is applied, and at the same time, resin molecules are interposed through metal molecules. Combined to form a polymer or a three-dimensional cross-linked structure,
A more dense and tough coating film is obtained. Further, rust components (metal ions) generated in a corrosive environment are complexed to form a stable compound, and rust growth is suppressed.

[0042]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to these. All parts and percentages are by weight.

Production Example 1 (Production of Latex A-1 of Vinylidene Chloride Copolymer) Raw Material Part Solid Content (Parts) ────── Deionized water 96.3 Aqualon RN-20 1.0 1.0 (Daiichi Kogyo Seiyaku Co., Ltd., vinyl group-containing polyoxyethylene alkyl phenol ether) Potassium persulfate 0.2 0. 2 Vinylidene chloride 80 80 Butyl acrylate 16 16 Glycidyl methacrylate 44 Potassium persulfate 0.05 0.05 Deionized water 4.95 ───────── Total 202.5 101.25

In a glass-lined autoclave with a stirrer, the above raw materials were charged and heated to 45 ° C.
After sufficiently replacing the inside of the vessel with N ₂ gas, a mixture of, was continuously added at a constant rate over 18 hours. Thereafter, the mixture was stirred at 45 ° C. for 1 hour, and then the mixture was
Add at a constant rate over time. The mixture was further stirred at 45 ° C. for 3 hours to obtain Latex A-1 having a solid content of 50% (vinylidene chloride content: 79.0%).

Production Example 2 (Production of Latex A-2 of Vinylidene Chloride Copolymer) A solid content of 50% (vinylidene chloride content 59%) was produced in exactly the same manner as in Production Example 1 except that only the polymerizable monomer was changed as follows. (0.3%) of latex A-2. Raw material part Solid content (parts) ビ Vinylidene chloride 60 60 Butyl acrylate 35 35 Methacrylic acid 55

Production Example 3 (Production of Acrylic Emulsion Solution A-3 Containing No Vinylidene Chloride) Raw Material Part Solid Content (Parts)脱 Deionized water 98.3 Aqualon RN-20 2.0 2.0 Potassium persulfate 0.2 0.2 Methyl methacrylate 80 80 Butyl acrylate 16 16 Glycidyl methacrylate 44 Potassium sulfate 0.05 0.05 Deionized water 4.95 Total 205.5 102. 25

The mixture was charged into a 14-neck flask equipped with a stirrer, a condenser and a thermometer, and the temperature was maintained at 60 ° C. while flowing N ₂ gas. Next, the mixture was dropped at a constant speed over 1 hour, and then stirred at 60 ° C. for 1 hour. Next, the mixture was added, and stirring was further continued at 60 ° C. for 1 hour to obtain an acrylic emulsion solution A-3 having a solid content of 50% (vinylidene chloride: 0%).

Production Example 4 (Production of Aqueous Dispersion B-1 of Amine-Modified Epoxy Resin) Raw Material Part Solid Content (Parts) Solid Content Ratio ＥＳ ESA-011P 950 950 81.9 (Bisphenol A type epoxy resin manufactured by Sumitomo Chemical Co., Ltd., epoxy equivalent 475) Methoxypropanol 497 Diethanolamine 210 210 18.1 ─────────────────────────────── Total 1657 1160 100

A 2 14-necked flask equipped with a stirrer, a condenser, and a thermometer was charged, heated to 100 ° C. to dissolve, and added, and reacted at 120 ° C. for 2 hours.
An amine-modified epoxy resin liquid C-1 having an epoxy resin solid content ratio of 81.9% and a solid content of 70% was obtained.

Raw material part Solid content (parts) ───────────────────────────── Amine-modified epoxy 1500 1050 Resin liquid C- 1 Acetic acid 37.8 Deionized water 1087.2 Total 2626 1050

Next, a 5 l stainless steel cylindrical container was charged and gradually added with stirring with a disperser to obtain a stable emulsion solution B-1 having a solid content of 40%.

Production Example 5 (Production of Aqueous Dispersion B-2 of Thiol Group-Containing Amine-Modified Epoxy Resin) Raw Material Part Solid Content (Part) Solid Content Ratio {ESA-011P 950 950 61.5 Methoxypropanol 662 Pentaerythritol 489 489 31.7 Tetra (mercaptopropionic acid) ester diethanolamine 105 105 6.8} ──────────────────────────── Total 2206 1544 100

A 3ｌ4-necked flask equipped with a stirrer, a condenser and a thermometer was charged, heated to 100 ° C. to dissolve, and then cooled to 50 ° C. In addition, add
After maintaining at 65 ° C. for 2 hours, the temperature was raised to 120 ° C., and the temperature was maintained for 2 hours, and a thiol group-containing amine having an epoxy resin solid content ratio of 61.5%, a complexing agent solid content ratio of 31.7% and a solid content of 70% was used. A modified epoxy resin liquid C-2 was obtained.

Raw material part Solid content (part) ───────────────────────────── Epoxy resin liquid 1000 700 C-2 Vinegar Acid 25.2 Deionized water 724.8 Total 1750 700

Next, a 3 l stainless steel cylindrical container was charged and gradually added while stirring with a disper to obtain an emulsion solution B-2 having a solid content of 40%.

Production Example 6 (Production of aqueous dispersion B-3 of phenolic hydroxyl group-containing amine-modified epoxy resin) Raw material part Solid content (part) Solid content ratio ESA-011P 950 950 77.5 Methoxypropanol 519.4 Gallic acid 170 170 13.9 Tributylamine 5.6 Diethanolamine 105 105 8.6 ───────────────────────────── Subtotal 1750 1225 100

A 3 / 4-necked kolben equipped with a stirrer, a cooling pipe and a thermometer was charged, heated to 100 ° C. to dissolve, and added, and the mixture was heated to reflux temperature and reacted for 5 hours. Further, after cooling to 100 ° C., the mixture was reacted at 100 ° C. for 2 hours, and a phenolic hydroxyl-containing amine-modified epoxy resin having an epoxy resin solid content ratio of 77.5%, a complexing agent solid content ratio of 13.9% and a solid content of 70% was added. Liquid C-3 was obtained.

Raw material part Solid content (parts) ───────────────────────────── Epoxy resin liquid 1000 700 C-3 vinegar Acid 25.2 Deionized water 724.8 Total 1750 700

Next, a 3 l stainless steel cylindrical container was charged and gradually added while stirring with a disper to obtain an emulsion solution B-3 having a solid content of 40%.

Examples 1 to 5 and Comparative Examples 1 to 7 Water-dispersed solutions of vinylidene chloride copolymer latex, epoxy resin or modified epoxy resin shown in Production Examples 4 to 6 above in the proportions shown in Table 1. A compound having a functional group capable of forming a complex compound with a metal ion is charged into a stainless steel cylindrical container, sufficiently stirred to obtain a stable emulsion solution, and then a carbon black is added to the emulsion solution 100.
Was added at a ratio of 0.5 part to the mixture, and the mixture was dispersed by a bead mill to form a paint.

A cold-rolled steel sheet and a galvannealed steel sheet are dipped in the paint thus obtained for 30 seconds, applied, left at room temperature for 10 minutes, and further dried in a drying furnace maintained at 60 ° C. for 20 minutes. I let it.

The coated plate thus obtained was subjected to various tests, and the obtained results are shown in Table 1.

Example 6 After further adding water to the paint prepared in the same manner as in the above example to make the solid content 20%, a stainless steel plate of the same size was immersed as a counter electrode of the object to be coated, and the object to be coated was 1 as cathode
After applying a direct current of 00 V for 2 minutes to perform electrodeposition coating, the same drying as in the other examples was performed.

The coated plate thus obtained was subjected to various tests, and the obtained results are shown in Table 1.

[0065]

[Table 1]

[0066]

[Table 2]

[0067]

[Table 3]

[0068]

[Table 4]

[0069]

[Table 5]

(Note 1) Included in the modified epoxy resin liquid B-2. (Note 2) Included in the modified epoxy resin liquid B-3. (Note 3) Solid parts by weight of each component based on 100 parts by weight of the above solids. (Note 4) (a): Cold-rolled steel sheet 70 mm in width and 150 in length
(b): 45 g / m ² of galvannealed alloy in (b)
The test pieces (A) and (B) are both manufactured by Japan Test Panel Co., Ltd. (Note 5) The number of tapes peeled out of 100 1 mm squares. (Note 6) JIS K-5400-9-1 Maximum one-sided width [mm] of rust and blisters from the cross cut part.

[0071]

By using the water-based rust-preventive coating composition of the present invention, a coating film having excellent adhesion to iron and various metals and excellent rust-preventive power can be formed. The painting method is
Any of brush coating, spray coating, dip coating, and electrodeposition coating can be used, and drying can be performed at a relatively low temperature of room temperature to 120 ° C.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C09D 5/08 C09D 127/16 C09D 163/00

Claims (5)

(57) [Claims] 1. A latex (A) of a vinylidene chloride polymer or a copolymer of vinylidene chloride and a vinyl group-containing monomer copolymerizable therewith, and an epoxy resin (B) which can be dissolved or dispersed in water, and It contains a complexing agent (C) which is a compound having a functional group capable of forming a complex compound with a metal ion, and the solid content of (A) is 30% by vinylidene chloride content.
To 65 parts by weight, the solid content of (B) is 1 to 30 parts by weight,
An aqueous rust preventive coating composition, wherein the solid content of (C) is 5 to 40 parts by weight. 2. The epoxy resin (B) which can be dissolved or decomposed in water is a diglycidyl ether of a polyalkylene oxide or a diglycidyl ether of a polyalkylene oxide adduct to polyphenol. Water-based rust-preventive paint composition. 3. An epoxy resin (B) which can be dissolved or dispersed in water, characterized in that a reaction product of a polyglycidyl ether of polyphenol and a secondary amine is neutralized with an organic acid or an inorganic acid. The water-based rust-preventive coating composition according to claim 1. 4. The aqueous rust preventive coating composition according to claim 1, wherein a compound having a phenolic hydroxyl group, thiol group or phosphate group as a functional group capable of forming a complex compound with a metal ion is used. 5. The complexing agent (C) according to claim 2 or 3.
The aqueous rust preventive coating composition according to claim 1, wherein the epoxy resin is reacted with a part or all of the compound having a functional group according to claim 4.