JPS5913269B2 - Coating film formation method with chelate layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 15 The present invention relates to a method for forming an iron chelate layer at the same time as overcoating the surface of a coating film of a resin composition having chelate-forming ability.

Vehicles conventionally used for paints include a wide variety of resins, including unsaturated fatty acids, alkyds, olefins, dienes, acrylics, polyesters, epoxies, urethanes, and copolymers thereof. Among these, the demand for epoxy resins is increasing due to their excellent physical properties (adhesion, hardness) and chemical properties (chemical resistance). In recent years, there has also been a demand for paints that are not dangerous, such as those that have low flammability or are not toxic to the human body. As one of these, a so-called water-based paint 30 has been developed in which an epoxy resin is used by dispersing, emulsifying, or dissolving it in water.

Known examples of such water-based epoxy resin coating compositions include, for example, U.S. Pat.
No. 397, No. 3324041, No. 3355409
No. 3449281 and No. 35 and No. 3640926
Already known as the number etc.

Although many other compositions have been researched and developed, they are still not as good as solvent-based compositions in terms of moisture resistance, corrosion resistance, physical properties, etc.

As an improvement, it has been proposed to add anti-corrosion pigments such as lead cyanamide, lead zinc oxide, basic lead chromate, red lead, strontium chromate, zinc chromate, etc. to improve corrosion resistance. It is considered unfavorable from this point of view.

Furthermore, various physical properties such as moisture resistance and corrosion resistance are not always satisfied.

On the other hand, compounds with chelate binding properties such as polyvalent phenols such as pyrogallol, phenol carboxylic acids, chromium complex salts, phthalocyanines, pyridines, and their derivatives are blended into the paint, and after application, they chelate with the iron surface of the substrate. Attempts have been made for a long time to improve the performance of coatings by carrying out reactions. Solvent-based paints have long been known, in which tannins are simply added to linseed oil-based resins or drying oils.

(British Patent Nos. 826564 and 826566)
After that, R. N. Vegetable oil, by FauIkner et al.
Solvent-based one-component type in which catechol, pyrogallol, gallic acid, or gallic ester is covalently introduced into fatty acid ester, alkyd resin, vegetable oil-modified epoxy ester resin, or vegetable oil-modified polyamide resin using a catalyst such as a metal alkoxide. paint was developed.
For example, British Patent No. 1045118, U.S. Patent No. 330
No. 4276 and No. 3321320 and Oi1and
C010urCnemists'AssOciatiO
nPublisherJournalOftheOilandCOl
Our Chemists'AssOciatiOn No. 5
Published in Volume 0, Page 524 (1967), etc. Furthermore, British Patent No. 1114400 discloses a composition in which a styrene allyl alcohol copolymer is reacted with a gallic acid ester.

Furthermore, compositions having chelate-forming ability using epoxy resins are also known.

For example, a part of the epoxy groups in an epoxy resin is modified with a monobasic fatty acid, and the epoxy resin has two or more adjacent phenolic hydroxyl groups and one free carboxyl group that has the ability to form a chelate with the remaining epoxy groups. Chelate-forming resin reacted with a fatty acid derivative having
No.), a composition comprising an epoxy-polyamide resin with chelate-forming ability obtained by reacting gallic acid with the residual epoxy group of a reaction product of a polyamide resin with an amine value of 10 or less and an epoxy resin, and a phosphoric acid compound (Unexamined Japanese Patent Publication No. Showa 48-17
No. 443), an organic product obtained by adding an epoxy resin, a vinyl resin, a fluororesin, etc. to a partially esterified product obtained by reacting a part of the epoxy group in an epoxy resin with salicylic acid, gallic acid, or an esterified product thereof. One-component type or two-component type (using amine curing agent) paint diluted with a solvent (Japanese Patent Publication No. 49-4811, JP-A-48-56227, JP-A-48-56228, JP-A-49-12253)
No. 8, Japanese Unexamined Patent Publication No. 49122597). However, all of these are made by modifying the base epoxy resin with a compound having chelate-forming ability.

In other words, it is a one-component or two-component composition in which all or part of the epoxy groups in the epoxy resin are reacted with a compound having chelate-forming ability, and it significantly deteriorates the properties of the epoxy resin. .

The present inventors have improved these points and developed a chelate-forming composition consisting of an epoxy resin emulsion and a curing agent composition in which protocatechuic acid and/or gallic acid, or their esters are "bound" to an amino-based curing agent. We proposed a water-based epoxy resin composition having the following properties.

(Japanese Patent Applications No. 50-19332, No. 50-127203) It has been discovered that when this resin composition is applied to an iron substrate, a chelation reaction occurs for the first time, providing an undercoat film with excellent corrosion resistance such as moisture resistance. The said application was filed.

However, subsequent research revealed that when a resin composition such as the one described above is applied to an iron base surface, a chelation reaction occurs between the base surface and the groups in the composition that have chelate-forming ability, and the surface layer of the resulting film also undergoes a chelation reaction. It was found that a considerable amount of groups with formation ability remained, and by applying a top coat containing an iron compound on top of this to form a chelate layer between the undercoat and soil coating, moisture resistance was achieved. The present invention was achieved by discovering that the properties, salt spray resistance, and secondary adhesion (to the substrate and between layers) after the salt spray resistance test could be improved.

In other words, the present invention provides a coating layer with excellent moisture resistance, corrosion resistance, and secondary adhesion by providing a chelate reaction layer between the substrate and the undercoat film and between the undercoat film and the topcoat film. This is the purpose.

That is, the present invention provides: (1) l) an aqueous dispersion of an epoxy resin having at least two or more epoxy groups in one molecule; and (11) two or more nitrogen atoms having at least two active hydrogen atoms in one molecule. A water-based epoxy resin composition consisting of an amino curing agent containing 5 to 30 weight percent of phenolcarboxylic acids and having chelate-forming ability is used as an undercoat film, and an iron compound is applied on the coating film. This invention relates to a method for forming a coating film having an iron chelate layer on the surface of the undercoat coating, which comprises applying a topcoat containing the following.

In other words, when the top coat of the present invention is applied, the phenolcarboxylic acids that exist on the surface of the undercoat and have chelate-forming ability react with the iron compounds contained therein to form an iron chelate layer on the surface of the undercoat. Ru.

The coating layer thus obtained has sufficient interlayer adhesion and excellent corrosion resistance even under various corrosive conditions. Examples of the "epoxy resin having at least two or more epoxy groups in one molecule" used in the undercoating paint of the present invention include the following. As a bisphenol type epoxy resin, the trade names Epicote 828 and 8 manufactured by Ciel Kagaku Co., Ltd. are generally commercially available.
34, 836, 1001, 1004, DX-2
55; Trade name: Araldite GY, manufactured by Ciba-Geigi Co., Ltd.
-260; Product name: DER33 manufactured by Tau Chemical Co., Ltd.
Ol 331, 337; Dainippon Ink & Chemicals Co., Ltd.
Product names: Epicron 8001 and 830 manufactured by Tau Chemical Co., Ltd.; Novolac type epoxy resins such as DEN43l and DEN438 manufactured by Tau Chemical Co., Ltd.; Polyglycol type epoxy resins such as Araldite CT5O8 manufactured by Ciba Geigi Co., Ltd.; Trade names DER732 and DER736 manufactured by Tau Chemical Co., Ltd.; ester-type epoxy resins such as Epiclon 2001 400 manufactured by Dainippon Ink and Chemicals; and epoxidized polybutadiene manufactured by Nippon Soda Co., Ltd. Product name: BF-1000;
Examples of the epoxidized oil include ADEKA SIZA 10-1801 0-130P manufactured by ADEKA ARGUS CHEMICAL CO., LTD. Furthermore, it should be noted that epoxy compounds and derivatives of the above-mentioned epoxy resins that can be easily inferred from these exemplified compositions are also included within the scope of the present invention.

For example, polyol-type epoxy resins, alicyclic epoxy resins, halogen-containing epoxy resins, silicon-modified epoxy resins, and the like can be used in the present invention to obtain excellent effects. These epoxy resins may be used alone or as a mixture of two or more thereof. It is preferable that the epoxy resin is liquid at room temperature in order to improve water dispersibility, but even if the epoxy resin is solid at room temperature, it may be used in combination with a liquid epoxy resin or by adding a small amount of a water-soluble solvent. It can be used better.

Furthermore, in order to make it easier to emulsify the epoxy resin, which is solid at room temperature, in water, or to improve workability, coating performance, and coating condition, monoepoxy compounds having one epoxy group in the molecule may be added as necessary. It can be used in combination up to 20% by weight with respect to the epoxy resin.

Examples of the monoepoxy compound include allyl glycidyl ether, 2-ethylhexyl glycidyl ether,
Methyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, styrene oxide,
Examples include cyclohexene oxide, epichlorohedrin, and a compound having one epoxy group obtained by modifying an epoxy resin having two or more epoxy groups in the molecule with a fatty acid or the like.

The epoxy resin used in the present invention is used in the form of an aqueous dispersion, and the aqueous dispersion refers to an epoxy resin emulsified in an aqueous medium, and is generally anionic and/or nonionic. It is obtained by vigorously stirring water and epoxy resin in the presence of a surfactant.

In addition to the above-mentioned emulsified aqueous dispersion of the present invention, a dispersion in which an epoxy resin is partially dissolved in water can also be used.

However, when dissolved in water, epoxy groups tend to ring open and do not exhibit sufficient coating performance, so care must be taken when using them. Examples of the anionic surfactants include metal salts of fatty acids, alkylbenzenesulfonates [
For example, manufactured by Kao Astra Co., Ltd., product name Neoperex 0
5) Sulfuric esters of higher alcohols (for example, manufactured by Kao Aslus Co., Ltd., trade name Emar 10) and the like.

In addition, as the nonionic surfactant, polyoxyethylene alkyl ether [for example, Kao Atlas Co., Ltd.
Emulgen 108 (trade name), Solpit derivatives (e.g., Emazol 11.30, manufactured by Kao Atlas Co., Ltd.), polyoxyethylene alkyl fluorinyl ether (e.g., manufactured by Nippon Nyukazai Co., Ltd., name: Ni-Ucol 7101-7)
14, 723], polyoxyethylene anolequinoleester (for example, manufactured by Nippon Nyukazai Co., Ltd., trade name 2-Ucol 150), and the like. The above-mentioned surfactants may be used alone or in a mixture of two or more, as required, and the amount added varies depending on the type of surfactant and epoxy resin.

If the surfactant is used in an amount greater than the required amount, it will have unfavorable effects such as a decrease in the water resistance of the coating film, so it is desirable to keep the amount as small as possible while taking dispersion stability into consideration.
Generally, 0.1 to 20 weight percent surfactant is added to the epoxy resin. In this way,
An aqueous dispersion (main ingredient of undercoat) is obtained by dispersing approximately 40% by weight of epoxy resin in water.

The main ingredients of the undercoat paint mainly composed of the epoxy resin include extender pigments such as talc, precipitated barium sulfate, and calcium carbonate, yellow lead, carbon black, titanium oxide, zinc white, red oxide, and phosphorous flakes. colored pigments such as iron oxide, aluminum powder, ultramarine blue, phthalocyanine blue, and iron black; reinforcing pigments such as glass fiber, glass flakes, mica powder, synthetic silica, and asbestos; other thickeners, rust preventive agents, and non-pollution preventive agents. Rust pigments, antifoaming agents, wetting agents, anti-settling agents, hardening accelerators, etc. can be added.As the rust preventive agents or non-polluting rust preventive pigments, conventionally known sodium nitrite, phosphoric acid, phosphoric acid, etc. Examples include ammonium, zinc phosphate, zinc molybdate, barium metaborate, iron phosphate, and the like.

Examples of the curing accelerator include phenol, cresol, nonylphenol, bisphenol A1 salicylic acid, resorcinol, hexamethylenetetramine, 2,4,6-tris(dimethylaminomethino(ha)phenol), and triethylenediamine.

Particularly when a tertiary amine is used, it is effective in low-temperature curability.
Further, in the present invention, in order to improve the coating workability, coating performance, surface condition of the coating film, etc. of the undercoat composition, other resins may be used in combination with the epoxy resin in an amount of 20% by weight or less based on the epoxy resin. .

Examples of the resins used in combination include alkyd resins, polyester resins, urethanized oils, xylene resins, and bituminous resins. On the other hand, "
"Amino curing agent having two or more nitrogen atoms and having at least active hydrogen in one molecule" refers to amine adduct resin, which is usually used as a curing agent for epoxy resin,
Amino compounds such as polyamide resins and polyamines can be used.

The polyamide resin is a condensation of dimer acid (general industrial products contain about 3% monomer acid, about 85% dimer acid, and about 12% trimer acid) and polyamines such as ethylenediamine, diethylenetriamine, or metaphenylenediamine. It is a product.

For example, commonly available products manufactured by Fuji Kasei Kogyo Co., Ltd. under the trade names Tomide Y-25, Tomide 245, Tomide 24001 and Tomide 25.
00; Product name: Zeminado 2000 manufactured by Daiichi General Co., Ltd.
, Versamide 115, 125, DSX-1280;
Sanwa Kagaku Co., Ltd. product name Sanmide 3201 330;
Manufactured by Ciel Kagaku Co., Ltd. Product name: Epicure 1 3255, 4
255 etc. are mentioned. Further, the amine adduct resin is
It is an addition product of the above-mentioned epoxy resin such as bisphenol type epoxy resin and polyamines such as ethylenediamine, diethylenetriamine or metaphenylenediamine. For example, commercially available products such as Tomide 238 and Fujiki Yua 202 manufactured by Fuji Chemical Industry Co., Ltd.
; Manufactured by Asahi Denka Co., Ltd. Product name: ADEKA Hardener EH-531
etc. Further, as the amine adduct, there are also addition products of butyl glycidyl ether, glycidyl ester of versatic acid, bisphenol type epoxy resin, etc., and a heterocyclic diamine represented by the following formula, for example.

For example, there are commercially available products such as Epomate B-002, Epomate C-002, and Epomate SOO5 manufactured by Ajinomoto Co., Inc.

These curing agents may be used singly or as a mixture of two or more depending on the purpose. The amino curing agent is required to have at least two or more nitrogen atoms containing active hydrogen in one molecule in order to bond with a compound having chelate-forming ability and further perform a crosslinking reaction with an epoxy resin.

Regarding the curing agent, there are no other restrictions, but it is preferable that the amine value is 100 or more in view of dispersion in water. However, if the amine value of the curing agent becomes extremely high, there will be a restriction that the pot life after mixing with the epoxy resin as the main ingredient will be shortened. Furthermore, the viscosity of the curing agent also has a large effect on the performance of the paint and the performance of the coating film. Generally, the higher the viscosity of the curing agent used, the worse the coating workability and the shorter the pot life. It can be improved by adding small amounts of water-soluble solvents. Examples of the water-soluble solvent include alcohols such as methanol and ethanol, and ethers such as ethylene glycol monoethyl ether and ethylene glycol monobutyl ether. In the present invention, a compound having chelate-forming ability must be introduced into the amino curing agent.

Examples of the compound having the chelate-forming ability include phenolic carboxylic acids such as gallic acid, protocatechuic acid, and alkyl esters thereof.

The amino-based curing agent having chelate-forming ability used in the present invention can be obtained by ionically bonding the above-mentioned compound having chelate-forming ability to the amino-based curing agent as a salt, or by curing the carboxyl group of the compound having chelate-forming ability into an amino-based curing agent. It is covalently bonded as an acid amide by condensation with active hydrogen such as an amino group of an agent. When a compound having chelate-forming ability, ie, phenolcarboxylic acids, is introduced into the amino curing agent as a salt, protocatechuic acid, gallic acid, etc. are used.

In addition, when a compound having chelate-forming ability is introduced as an acid amide bonded to an amino curing agent, protocatechuic acid, gallic acid, ethyl protocatekyate, propyl protocatekyate, methyl gallate, ethyl gallate, propyl gallate, etc. Alkyl esters of protocatekylic acid or gallic acid having 1 to 12 carbon atoms in the alkyl group, such as isoamyl gallate and lauryl gallate, are used.

The amount of the phenol carboxylic acids is 5 to 30% by weight, preferably 10 to 2% by weight, based on the solid content of the amino curing agent.
It is used in a proportion of 5% by weight. If the amount of the compound having chelate-forming ability in the above ratio is less than 5% by weight, the desired effect of the present invention cannot be expected, whereas if it exceeds 30% by weight, not only is it not easy to disperse, but also more chelate than necessary is formed. In this case, the coating film obtained becomes hard and brittle, and the moisture resistance is also reduced, and it is also uneconomical, which is not very preferable. The phenolcarboxylic acids in the present invention are bonded to the amino curing agent in the following manner. First, a phenolcarboxylic acid and an amino curing agent are mixed in the presence of water, and the mixture is stirred at any temperature from room temperature to 100°C.

By doing so, the carboxyl group in the phenolcarboxylic acid and the nitrogen atom having an active hydrogen atom in the amino curing agent form a salt through ionic bonding, and a stable reaction product is obtained. Another method is to remove the produced water or alcohol from the system by combining the phenolcarboxylic acids and the amino curing agent at a temperature of 100 to 240°C until the desired amount of condensed water or alcohol is obtained (
The mixture is heated and stirred for 2 to 10 hours (usually for 2 to 10 hours) in the presence of an inert gas such as nitrogen gas.

By doing so, a reaction product in which the phenolcarboxylic acids are condensed and introduced into the amino curing agent is obtained.

The amino curing agent having chelate-forming ability thus obtained crosslinks with the epoxy resin and also performs a chelate reaction with the iron compound in the base iron surface and the top coat.

Furthermore, the chelate-forming ability can be increased by mixing 2 to 30 weight percent of tannin with the amino curing agent having chelate-forming ability used in the undercoat of the present invention.

In the undercoat used in the present invention, the aqueous dispersion of the epoxy resin and the amino curing agent into which a phenolcarboxylic acid having chelate-forming ability is introduced are each separately used in the undercoat used in the present invention. cannot achieve the purpose of

That is, it is necessary to mix the epoxy resin aqueous dispersion and the amino curing agent having chelate-forming ability before use. In order to effectively carry out the crosslinking reaction and obtain excellent coating performance, the mixing ratio is usually (number of epoxy groups in the base resin)/(
1 (number of active hydrogens bonded to nitrogen atoms in the curing agent)
A ratio of /2 to 2/1 is preferred. However, this ratio is not particularly limited. Thereafter, it is applied to the object to be coated by a common method such as brush painting, air spray painting, airless spray painting, or roll coater painting, to form an undercoat film.

After coating, it is dried at a temperature of 10° C. to 150° C. and a relative humidity of 97% or less to form an undercoat film.

In order to meet the required performance, the dry film thickness of the undercoat film is required to be at least 50 microns. The object to be coated is preferably a steel material such as mild steel or hard steel;
It can be applied to degreased surfaces, chemically treated surfaces, rusted surfaces, wet surfaces, welded parts, etc. It can also be applied to nonferrous materials such as galvanized plates, tin plated plates, aluminum plates, copper plates, etc., and primer soils such as shot primers (for example, wash primers, zinc-rich primers, etc.). In the present invention, an earthen coating containing an iron compound is applied onto the undercoat film obtained as described above.

The top coating used in the present invention may be either water-based or solvent-based as long as it is a commonly used soil coating.

Examples of these include water-based or solvent-based paints such as acrylic resin, alkyd resin, chlorinated rubber, vinyl resin, polyester resin, and epoxy resin. However, there is no problem in using other water-based or solvent-based paints as long as they are stable when mixed with iron compounds.

Examples of the iron compounds include ferrous chloride, ferric chloride, iron citrate, iron acetate, ferrous bromide, ferric bromide, iron oxalate, ferrous nitrate, ferric nitrate, iron hydroxide, iron sulfate,
Examples include ferrous ammonium sulfate and ferric ammonium sulfate.

However, there is no problem in using other iron compounds as long as they undergo a chelation reaction with phenolcarboxylic acids having chelate-forming ability. The iron compounds may be used alone or in combination of two or more. The iron compound used in the present invention is preferably a water-soluble one if the top coating used is water-based, or a solvent that is compatible with the soil coating if it is a solvent-based one, e.g. Those soluble in alcohols, ether alcohols, etc. are preferably used.

The amount of iron compound added to the earthen coating is preferably 0.1 to 5.0 weight percent as iron content relative to the top coating.

If the amount added is less than 0.1% by weight, the desired effect of the present invention cannot be expected.
When the weight percentage is exceeded, the stability of the top coat generally tends to decrease and agglomeration tends to occur.

However, even if the iron compound is added in an amount of 5 weight percent or more as iron content to a general top coating, there is no problem in using it as long as the coating can be used stably. However, since most iron compound solutions have a pH range on the acidic side, the amount added may be limited from the viewpoint of stability. The iron compound used in the present invention is preferably diluted with water or a solvent.

Thus, when the water-based epoxy resin composition having chelate-forming ability is used as an undercoat film and a topcoat containing an iron compound is applied to the undercoat film that has been cured to an extent that lifting of the paint film does not occur, the undercoat The phenol carboxylic acids in the paint film and the iron compounds in the earthen paint cause a chelate reaction, and an iron chelate layer is formed on the surface of the undercoat film. Thus, according to the method of the present invention, an iron chelate layer can be formed between the iron substrate surface and the undercoat film and between the undercoat film and the topcoat film, and as a result, the iron chelate layer can be formed between the iron substrate surface and the undercoat film. A coating layer with superior moisture resistance, corrosion resistance (salt spray resistance), and secondary adhesion after salt spraying can be obtained compared to a coating in which only an iron chelate layer is formed. In the case of applying the soil paint, if the undercoat is a film that has been cured by heating and drying, there is no problem in immediately applying the topcoat, whether water-based or solvent-based.

However, if the undercoat dries to form a film at room temperature, the time from the time the undercoat is applied until the topcoat is applied is at least 6 hours at room temperature if the basecoat is water-based, or more than 6 hours at room temperature if the base coat is water-based, or if it is solvent-based. In the case of 24 hours or more at room temperature, the desired effect of the present invention can be sufficiently obtained. The top coat used in the present invention is applied onto the base coat by a common method such as brush painting, air spray painting, airless spray painting, or roll coater painting, and is then dried at room temperature or heated to dry the paint film. be done. The coating film thus obtained has extremely excellent interlayer adhesion even under various corrosive conditions, and also has extremely excellent properties such as corrosion resistance.

The details of the present invention will be explained below with reference to Examples.

"Parts" or "percents" are expressed as "parts by weight" or "percent by weight." Example 1 30 parts of talc, 10 parts of precipitated barium sulfate, 1 part of red iron
0 parts and 30 parts of water were stirred and mixed in a dispenser to obtain a pigment mixture.

Bisphenol type epoxy resin [trade name Epicote 828 manufactured by Ciel Kagaku Co., Ltd.: Epoxy equivalent weight 184-194
] 20 parts were emulsified in 8 parts of water using 2 parts of a nonionic surfactant [trade name 2-Ucol 723, manufactured by Nippon Nyukazai Co., Ltd.]. The above pigment mixture was added to the obtained epoxy resin aqueous dispersion and stirred to form a main ingredient. On the other hand, polyamide resin [product name Tomide 250 manufactured by Fuji Kasei Kogyo Co., Ltd.]
0: amine value 330±20], 7.5 parts of gallic acid, and 25 parts of water were stirred and mixed at room temperature for 1 hour to obtain an amino curing agent having chelate-forming ability.

8. Amino curing agent having chelate forming ability with the main agent.
They were mixed at a ratio of 4/16 (weight ratio) to obtain an undercoat paint composition used in the present invention.

Then, add water to 10 to 20 poise (Rion viscometer rotor.
The undercoat paint composition diluted to
It was air-sprayed to a thickness of 0 microns and dried in a constant temperature room (20° C., 75% PH) for 2 days to obtain an undercoat film. Next, 15 parts of titanium oxide, 4 parts of zinc white, 5 parts of precipitated barium sulfate, 55 parts of alkyd resin emulsion (45% non-volatile content), 15 parts of acrylic resin emulsion (50% non-volatile content), 5.5 parts of water, 0.5 part of a dryer was mixed and kneaded in a sand mill to obtain an alkyd-modified emulsion paint.

Two parts of a 15% aqueous solution of ferrous chloride were added to 10 parts of the alkyd-modified emulsion paint and mixed with stirring to obtain an iron compound-containing top coat. The top coat was applied to the undercoat with a brush to a dry film thickness of 50 microns, and after drying in a constant temperature room (20C, 75% PH) for 7 days, various performance tests were conducted.

The performance test results of the coating film thus obtained are shown in Table 1.

Example 2 An undercoat film was obtained in the same manner as in Example 1 above.

Next, 25 parts of titanium oxide, 15 parts of talc, 4 parts of calcium carbonate, 3 parts of precipitated barium sulfate, 25 parts of polyvinyl acetate emulsion (50% non-volatile content), 27 parts of water, 0.5 part of antifoaming agent, 0.25 part of preservative and 0.25 part of thickener were mixed and kneaded in a sand mill to obtain a vinyl emulsion paint. 0.8 parts of a 35% aqueous solution of ferric ammonium sulfate was added to 10 parts of the vinyl emulsion paint and mixed with stirring to obtain an iron compound-containing earthen paint. The soil paint was applied onto the undercoat film in the same manner as in Example 1, and after drying, various performance tests were conducted.

The performance test results of the coating films thus obtained are shown in Table 1.

Example 3 An undercoat film was obtained in the same manner as in Example 1 above.

On the other hand, to 10 parts of the alkyd-modified emulsion paint used in Example 1 was added 1.5 parts of a 15% aqueous solution of ferrous ammonium sulfate.
1 part and stirred and mixed to obtain an iron compound-containing top coat. The top coat paint was applied onto the undercoat film in the same manner as in Example 1, and after drying, various performance tests were conducted. The performance test results of the coating film are shown in Table 1.

Example 4 An undercoat film was obtained in the same manner as in Example 1 above.

However, the number of drying days after coating the paint was 5 days. Next, 25 parts of titanium oxide, 8 parts of precipitated barium sulfate, 50 parts of acrylic resin (non-volatile content 50%), vinyl resin (non-volatile content 4 parts),
0%), 0.2 parts of an antifoaming agent, 5 parts of methyl isobutyl ketone, and 2 parts of xylene were mixed and kneaded using a roller to obtain a solvent-type vinyl resin paint. 4 parts of a 25% ferrous chloride ethanol solution was added to 10 parts of the vinyl resin paint and mixed with stirring to obtain an iron compound-containing top coat. The soil paint was applied onto the undercoat film in the same manner as in Example 1, and after drying, various performance tests were conducted. The performance test results of the coating film thus obtained are shown in Table 1.

Example 5 An undercoat film was obtained in the same manner as in Example 4 above.

Next, soybean oil modified alkyd resin (80% non-volatile content) 33
Part, acrylic modified alkyd resin (non-volatile content 45%) 16
28 parts of titanium oxide, 5 parts of precipitated barium sulfate, 8 parts of calcium carbonate, 2 parts of a hair dryer, 2 parts of anti-sagging agent, and 1 part of mineral split were added and mixed. After that, the mixture was kneaded with a roller to obtain a solvent-type alkyd resin paint. Two parts of a 25% ferric chloride ethanol solution was added to 10 parts of the alkyd resin paint and mixed with stirring to obtain an iron compound-containing clay paint. The top coat paint was applied onto the undercoat film in the same manner as in Example 1, and after drying, various performance tests were conducted. The performance test results of the coating film thus obtained are shown in Table 1.

Example 6 A main ingredient was obtained in the same manner as in Example 1 above.

On the other hand, 100 parts of polyamide resin [same as Example 1] and 15 parts of n-propyl gallate were subjected to dealcoholization reaction in the presence of an inert gas at a temperature of 140-150°C until no distillate remained, and the chelate-forming ability was An amino curing agent having the following was obtained.

100 parts of the amino curing agent having chelate-forming ability was made into a curing agent solution with a non-volatile content of 70% using ethylene glycol monobutyl ether. The main agent and a curing agent solution having chelate-forming ability were mixed in a ratio of 83/17 (weight ratio) to obtain an undercoat coating composition for use in the present invention.

The composition was applied in the same manner as in Example 1 to obtain an undercoat film. Next, 12% of chlorinated rubber (80% non-volatile content) and 18 parts of phthalic acid alkyd resin (50% non-volatile content) were uniformly dissolved in 25 parts of xylol, and then 25 parts of titanium oxide,
Precipitated barium sulfate 5 parts, softener 5 parts, dryer 0.
2 parts and 10 parts of xylene were added and mixed, and kneaded with a roller to obtain a solvent-type chlorinated rubber paint.

Two parts of a 25% ferrous chloride ethanol solution was added to 10 parts of the chlorinated rubber paint and mixed with stirring to obtain an iron compound-containing top coat.

The soil paint was applied onto the undercoat film in the same manner as in Example 1, and after drying, various performance tests were conducted. The performance test results of the coating film thus obtained are shown in Table 1.

Comparative example 1 A main ingredient was obtained in the same manner as in Example 1.

The base material and polyamide resin (Tomide 2500) were mixed at 90%
/10 (weight ratio) to obtain an undercoat film in the same manner as in Example 1. Next, the alkyd-modified emulsion paint used in Example 1 was applied to the base coat soil in the same manner as in Example 1, and after drying, various performance tests were conducted.

The performance test results of the coating films thus obtained are shown in Table 2.

Comparative example 2 An undercoat film was obtained in the same manner as in Comparative Example 1 above.

Next, the vinyl emulsion paint used in Example 2 was applied as a top coat onto the undercoat film in the same manner as in Example 1, and after drying, various performance tests were conducted. The performance test results of the coating film thus obtained are shown in Table 2.

Comparative example 3 An undercoat film was obtained in the same manner as in Comparative Example 1 above.

However, the number of drying days after painting was set to 5 days. Next, the solvent-based vinyl resin paint used in Example 4 was applied as a soil coating onto the undercoat film in the same manner as in Example 1,
After drying, various performance tests were conducted. The performance test results of the coating film thus obtained are shown in Table 2.

Comparative example 4 An undercoat film was obtained in the same manner as in Comparative Example 3 above.

Next, the solvent-based alkyd resin paint used in Example 5 was applied as a top coat onto the undercoat film in the same manner as in Example 1, and after drying, various performance tests were conducted.

The performance test results of the coating film thus obtained are shown in Table 2.

Comparative example 5 An undercoat film was obtained in the same manner as in Example 6.

Next, the solvent-based chlorinated rubber paint (containing no iron compounds) used in Example 6 as a top coat was applied onto the undercoat in the same manner as in Example 1, and after drying, various performance tests were conducted. I did it.

The performance test results of the coating film thus obtained are shown in Table 2.

It is clear from Tables 1 and 2 that the coating layer obtained by the method of the present invention exhibits excellent performance in moisture resistance and salt spray resistance, and shows a marked difference in secondary adhesion. It was hot.

Claims (1)

[Scope of Claims] 1 i) an aqueous dispersion of an epoxy resin having at least two epoxy groups in one molecule; and ii) containing two or more nitrogen atoms having at least an active hydrogen atom in one molecule A water-based epoxy resin composition consisting of an amino curing agent having chelate-forming ability into which 5 to 30 weight percent of phenolic carboxylic acids have been introduced is used as an undercoat film, and an iron compound is contained on the coating film. A method for forming a paint film having an iron chelate layer on the surface of the undercoat film, which is characterized by applying a topcoat paint. 2. The coating according to claim 1, wherein the phenolic carboxylic acid is one or a mixture of two or more of protocatechuic acid, gallic acid, gallic acid whose alkyl group has 1 to 12 carbon atoms, or a protocatechuic acid alkyl ester. Film formation method. 3. The top coating according to claim 1, wherein the top coating is a water-based coating containing one or a mixture of two or more of ferrous chloride, ferric chloride, ferrous ammonium sulfate, and ferric ammonium sulfate. Paint film formation method. 4. The coating film forming method according to claim 1, wherein the top coating is a solvent-based coating containing at least one of ferrous chloride and ferric chloride. 5. The coating film forming method according to claim 1, 3 or 4, wherein the top coating is a coating containing an iron compound of 0.1 to 5.0 weight percent as iron content.