JPH0853644A - Aqueous coating composition - Google Patents

Abstract

(57) [Abstract] [Purpose] Aqueous coating composition for coating base which can improve space property by eliminating sludge treatment related to zinc phosphate treatment and waste liquid treatment, and corrosion resistance even without chromate treatment on zinc plating Provided are a lubricating rust preventive coating composition and a rust preventive coating composition for automobiles, which have a lubricity capable of retaining the above. [Structure] 100 parts by weight of a phosphoric acid modified product of a bisphenol type epoxy resin having an acid value of 5 to 35 due to a phosphoric acid group, an oxazoline compound, and a phenol resin,
And at least one type 10 to 500 selected from the group consisting of melamine resins having a curing start temperature of 140 ° C. or lower.
A composition containing 1 part by weight of a benzenesulfonic acid derivative, its amine salt and its ammonium salt, naphthalenesulfonic acid derivative, its amine salt and its ammonium salt, acidic phosphoric acid amine salt and ammonium salt, and phosphonic acid. An aqueous coating composition comprising 0.1 to 5% by weight of the entire composition of an acidic catalyst comprising at least one selected from the group consisting of a derivative, an amine salt thereof and an ammonium salt thereof.

Description

Detailed Description of the Invention

[0001]

The present invention relates to building materials, household electric appliances,
The present invention relates to an aqueous coating composition for treating the surface of a steel sheet used for automobiles and the like.

[0002]

2. Description of the Related Art Cold-rolled steel sheets and galvanized steel sheets are widely used for building materials, household appliances, automobiles and the like. These steel sheets are usually subjected to painting after forming and before assembling. At the stage of the forming process, a lubricating oil such as a press oil is applied to the surface of the steel sheet in order to improve its workability. However, with lubricating oil,
After pressing, a step of degreasing the lubricating oil is required before painting, which is economically disadvantageous, and the lubricating oil is scattered during the pressing and deteriorates the working environment.

Therefore, in recent years, for the purpose of resource saving, cost reduction, improvement of working environment, etc., a surface-treated steel sheet capable of forming a film having a lubricating function and a rust preventive function on the surface of a steel sheet without using a lubricating oil. Was proposed. Japanese Patent Laid-Open No. 5-394
Japanese Patent Laid-Open No. 58-58 discloses a technique of forming a resin film made of a specific polyethylene wax on the surface of a steel sheet to improve press formability and the like. Also, JP-A-1-3013
Japanese Unexamined Patent Publication No. 32 discloses a technique for obtaining moldability by double coating a specific amount of a chromate film and a resin film composed of a specific resin mixture.

From the viewpoint of labor saving, Japanese Patent Laid-Open No. 3-27093.
In JP-A-2, etc., the above-mentioned lubricating film is provided with anticorrosion properties and adhesion to a top coat film, and after the molding process, the top coat paint is directly applied to finish the coating, or the steel sheet for automobiles and the like is coated. For applications that require coating, a method of providing the conductivity necessary for the coating is disclosed. Further, Japanese Patent Application No. 4-290339 discloses a coating material whose conductivity is adjusted in order to improve water resistance and moisture resistance even in the field of general anticorrosion coating material.

In the production of the above coating composition, the use of an organic solvent deteriorates the working environment during processing,
The problems of ignition, the necessity of installing an afterburner to prevent the solvent from being discharged to the outside, and other problems have led to the development of aqueous coating compositions. In the composition of such an aqueous coating composition, the hydrophilic groups of the resin are increased to make it aqueous, and an emulsifier or the like for emulsifying the resin is added, which results in accelerating water penetration. This is a cause of lowering the water resistance and the corrosion resistance, and there has been a need for a technical means that does not deteriorate the water resistance and the corrosion resistance even if the water resistance is changed.

In recent years, in the surface-treated steel sheet production line on an industrial scale, energy saving and speeding up of treatment are being promoted. For example, at a relatively low temperature of about 150 ° C., 15
The current situation is that the requirements cannot be met unless the coating surface of the coating agent is cured in a short time of about a second to secure the film strength.

Further, recently, deep drawing and high speed processing have come to be performed. For this reason, the film on the processed part of the surface-treated steel sheet peels off due to the temperature rise of the mold, etc., and powder is generated (powdering), and the powder adheres to the processed part and the mold. There were problems such as deterioration of corrosion resistance of parts and deterioration of finished appearance.

Therefore, by baking at low temperature for a short time, it is possible to obtain a coating film having a high degree of curing and firmly adhering to a metal plate,
It is considered to provide an aqueous coating composition for steel plate surface treatment, which has excellent corrosion resistance, water resistance, and weldability, has conductivity suitable for electrodeposition coating, and can also prevent the occurrence of powdering during processing. Was done. As a result, the aqueous coating composition had an acid value of 25 to 100 and a hydroxyl value of 35 to 35.
200, 100 parts by weight of a resin varnish consisting of at least one of a water-soluble alkyd resin having a SP value of 10.0 to 11.0 and a water-soluble acrylic resin, an oxazoline compound, and a melamine resin having a curing start temperature of 140 ° C. or lower. From 10 to 200 parts by weight of at least one curing agent, benzenesulfonic acid derivative, its amine salt and its ammonium salt, naphthalenesulfonic acid derivative, its amine salt and its ammonium salt, and acidic phosphoric acid amine salt and ammonium salt It has been found that an aqueous coating composition suitable for the above purpose can be obtained by comprising 0.5 to 5 parts by weight of a strongly acidic catalyst consisting of at least one selected from the group consisting of

By the way, for example, in a current coil coating line for applying and baking a lubrication and rust preventive coating agent, the line speed is temporarily lowered due to occurrence of line trouble, switching of strip sheet, switching of paint and coating agent, etc. Often becomes. In such a case, an overbaked state occurs because the vehicle body stays in the oven at a constant temperature for a certain period of time, and after that, the curing becomes excessive during the process of baking again when applying the topcoat paint, and the final In some cases, the coating film adhesion and bending workability may be reduced. It has been found that such a danger cannot be avoided when the aqueous coating composition having the above-mentioned constitutions (1) to (3) is used as a lubricating and anticorrosive coating composition. Therefore, even if it becomes overbaked, the film adhesion,
A study was conducted to find out what does not deteriorate the bending workability.

As a result, a resin varnish comprising at least one of a water-soluble alkyd resin and a water-soluble acrylic resin having an acid value of 25 to 100, a hydroxyl value of 35 to 200, and an SP value of 10.0 to 11.0, A curing agent comprising at least one of an oxazoline compound and a melamine resin having a curing start temperature of 140 ° C. or lower, a benzenesulfonic acid derivative, an amine salt and an ammonium salt thereof, a naphthalenesulfonic acid derivative, an amine salt and an ammonium salt thereof, and It has been found that the object can be achieved by an aqueous coating composition containing a limited amount of a strongly acidic catalyst comprising at least one selected from the group consisting of an amine salt of an acidic phosphate and an ammonium salt, and a polyurethane resin emulsion. And applied for a patent.

[0011]

On the other hand, sludge is inevitably generated in the zinc phosphate treatment (hereinafter referred to as "chemical conversion treatment") used for the coating base of the steel sheet surface. In recent years, due to increasing concern about environmental problems, waste problems, etc., the cost of disposing sludge by-produced in the chemical conversion treatment process has increased, so there has been a demand for sludge-less conversion during chemical conversion treatment.
Further, from the viewpoint of cost reduction, not only the sludge disposal cost, but also the maintenance cost required for sludge treatment such as separation and coagulation sedimentation, the problem of space saving resulting from the need for a large space for chemical conversion treatment, pH, Due to problems such as complexity of control of chemical conversion treatment line liquid such as acidity, there has been a strong demand for an alternative surface treatment method to the chemical conversion reaction type zinc phosphate treatment.

As a coating base treatment instead of zinc phosphate treatment, coating type chromate treatment and reactive type chromate treatment have been put into practical use. According to this, proper base such as corrosion resistance and adhesion, and space saving of treatment process The above problems such as sex are solved. However, since the above chromate treatment contains hexavalent chromium, there is a problem in that there are emission regulations from the standpoint of occupational hygiene, working environment, environmental protection, etc., and the treatment for that is expensive.

Although various non-chromium type treating agents which do not use hexavalent chromium, etc. have been proposed, when they are used as a coating base for carbon steel and galvanized steel, the corrosion resistance deteriorates. It is applied only in specific fields such as post-treatment and aluminum can treatment.

The aqueous coating composition detailed above also comprises
A coating type chromate treatment and a reactive type chromate treatment were applied to the base, and hexavalent chromium was controlled in the treatment step, and it was necessary to dispose of it. In view of the above, the present invention is a sludge treatment related to zinc phosphate treatment, a water-based coating composition for a coating base that can improve space properties by eliminating waste liquid treatment, and corrosion resistance even without chromate treatment on zinc plating. It is an object of the present invention to provide a lubricating anticorrosion coating composition and an anticorrosion coating composition for automobiles, which have lubricity that can be retained.

[0015]

DISCLOSURE OF THE INVENTION The gist of the present invention is to provide an aqueous coating composition having an acid value of 5 to 35 by the phosphate group.
Bisphenol type epoxy resin modified with phosphoric acid 1
00 parts by weight, and at least one selected from the group consisting of an oxazoline compound, a phenol resin, and a melamine resin having a curing start temperature of 140 ° C. or lower 10
A benzenesulfonic acid derivative, an amine salt and an ammonium salt thereof, a naphthalenesulfonic acid derivative, an amine salt and an ammonium salt thereof, an acidic phosphoric acid amine salt and an ammonium salt, and The acidic catalyst comprising at least one selected from the group consisting of a phosphonic acid derivative, an amine salt thereof and an ammonium salt thereof is constituted by 0.1 to 5% by weight of the entire composition. The present invention is described in detail below.

The phosphoric acid modified product () of the bisphenol type epoxy resin used in the present invention has an acid value of 5 to 35 due to the phosphoric acid group. In the phosphoric acid modified product of the bisphenol type epoxy resin, when the acid value is a modified product other than phosphoric acid such as a carboxylic acid compound, it is vulnerable to peeling occurring in the cathode part when corrosion occurs, so at least 5 It is not preferable that ~ 35 is not due to a phosphate group.

Further, even the phosphoric acid-modified products of the above-mentioned bisphenol type epoxy resin modified with phosphoric acid are preferably phosphoric acid esters. For example, JP-A-5
-320566, JP-A-5-320569, etc. are modified with a carboxyl group-containing resin in order to add phosphoric acid ester instead of phosphoric acid to a bisphenol type epoxy resin and to have emulsifying property. A technique for introducing an emulsifying group is disclosed, but such a thing is
Even after it becomes a cured film, the carboxyl groups remain without disappearing, so the water resistance deteriorates in a film that requires high corrosion resistance and high wet adhesion, causing the film to peel off when used as a coating base etc. Therefore, it cannot be used in the present invention.

The weight average molecular weight of the phosphoric acid modified product of the bisphenol type epoxy resin is preferably 3,000 to 20,000. If it is less than 3,000, the corrosion resistance and wet adhesion are poor, and if it exceeds 20,000, the coating composition tends to thicken, the uniformity of the coating film tends to decrease, and the amount of the coating film tends to decrease.

Examples of phosphoric acid modified products of the above bisphenol type epoxy resin include XQ-82294.00,
XQ-82294.01 (acid value 35, weight average molecular weight 3
000, manufactured by Dow Chemical Japan), XQR-711
-1352.61 (acid value 22, weight average molecular weight 500)
0, manufactured by Dow Chemical Japan), XU-8096.0.
7 (acid value 12, weight average molecular weight 10000, manufactured by Dow Chemical Japan), XQR-711-1352.60
(Acid value 12, weight average molecular weight 10,000, manufactured by Dow Chemical Japan), XU-71899.00 (acid value 10,
A weight average molecular weight of 16000, manufactured by Dow Chemical Japan Co., Ltd.) is preferably neutralized with amine or ammonia, and the emulsion liquid after emulsification is adjusted to have a pH of 4.0 to 9.0.

In the present invention, an oxazoline compound,
At least one () selected from the group consisting of a phenol resin and a melamine resin having a curing start temperature of 140 ° C. or lower is used. The oxazoline compound used in the present invention has a structure represented by the following general formula [I]. The oxazoline compound easily reacts with a compound having a carboxyl group to cause the following ring-opening addition reaction.

[0021]

Embedded image

In the formula, R and R'represent various polymers. In the present invention, R is preferably a styrene-based polymer or an acrylic-styrene-based copolymer from the viewpoint of imparting the toughness of the coating film and increasing the glass transition temperature. The oxazoline compound is not particularly limited, but for example, Epocros K-1010E and Epocros K-10 manufactured by Nippon Shokubai Co., Ltd.
20E, Epocros K-1030E, Epocros K-1
050E and the like can be mentioned, and among these, Epocros K-1030E and Epocros K-1050E are preferable because they give a coating film having a high glass transition temperature, toughness, and high adhesion. Further, even with Epocros K-1010E and Epocros K-1020E, the addition amount, the curing temperature, and the catalyst can be adjusted and used so that the produced coating film becomes a desired film.

The oxazoline compound used in the present invention preferably has a glass transition temperature of 0 ° C. or higher. 0 ° C
When it is less than, low temperature and short time (about 150 seconds at 150 ° C)
Under the above baking conditions, a coating film excellent in adhesion to a steel plate and curing degree cannot be obtained.

The phenolic resin used in the present invention is not particularly limited as long as it is an aqueous phenolic resin. For example, the phenolic resin produced by the production method disclosed in JP-A-4-283217, JP-A-5-93167 or the like can be used. , Showa High Polymer Co., Ltd. Shownol BRL-125S, 126A and other highly water-soluble resol type phenolic resin; Shownol BRL-1
17, 134, 1583, 230C, 273Z, 276
O, 280Z, 204, 219, 1251, 2534,
Examples thereof include water-soluble resol type phenolic resins such as 113, 116, 120Z and 112A; aqueous emulsions such as BRE-174 and N-2.

The melamine resin used in the present invention has a curing initiation temperature of 140 ° C. or lower. If it is higher than 140 ° C, the curing degree of the coating film will be insufficient at low temperature and short baking time. Among them, those having a high curing rate are preferable. As the melamine resin, an imino or methylol modified or mixed modified melamine resin is preferable. Butoxy-modified melamine resin is not preferable because it is inferior in uniform mixing property with a water-soluble resin and the stability of the coating composition is reduced.

As the melamine resin satisfying the above conditions, for example, imino type melamine resins such as Cymel 327 and Cymel 328 (manufactured by Mitsui Cyanamid); Cymel 370.
(Mitsui Cyanamid Co., Ltd.) and the like, methylol-modified melamine resin or a mixture-modified melamine resin thereof, and the like.

The content of at least one kind () selected from the group consisting of the oxazoline compound, the phenol resin and the melamine resin is 10 based on 100 parts by weight of the phosphoric acid modified product () of the bisphenol type epoxy resin.
~ 500 parts by weight. If it is less than 10 parts by weight, curing will be poor, and if it exceeds 500 parts by weight, the curing agent remains unreacted, which causes softening of the cured film, lowering of glass transition temperature, lowering of adhesion, and lowering of water corrosion resistance. Therefore, it is limited to the above range. More preferably, it is 10 to 200 parts by weight with respect to 100 parts by weight.

In the present invention, benzenesulfonic acid derivatives, amine salts and ammonium salts thereof, naphthalenesulfonic acid derivatives, amine salts and ammonium salts thereof, acidic phosphoric acid amine salts and ammonium salts, and phosphonic acid derivatives thereof. An acidic catalyst () comprising at least one selected from the group consisting of amine salts and ammonium salts thereof is used.

As the cation forming the salt of the acidic catalyst, amines and ammonium are preferable because they are volatilized during the heat curing of the coating film and hardly remain in the coating film. Alkali metals and metal cations are not preferable because they are ionized in the paint and remain in the coating film, causing absorption of water. Examples of the acidic catalyst include dodecylbenzene sulfonic acid, dinonylnaphthalene sulfonic acid, ammonium dihydrogen phosphate, ammonium monohydrogen phosphate, catalyst 5
00 (Mitsui Cyanamid), Catalyst 600
(Same), Catalyst 4040 (Same), and the like.

Among the above acidic catalysts, the acidic phosphoric acid may be an inorganic phosphate such as ammonium dihydrogen phosphate or ammonium monohydrogen phosphate, or a phosphoric acid group bonded to a resin. For example, it may be a phosphoric acid modified product of polyvinyl alcohol or a phosphoric acid modified product of the above bisphenol type epoxy resin. When these are used, the low molecular weight acidic catalyst may not be added or only a very small amount may be added. As the acidic phosphoric acid, polyvalent phosphoric acid such as phytic acid may be used. In this case, the substance itself has a rust prevention function in addition to the catalyst function,
Corrosion resistance can be enhanced.

The phosphonic acid derivative, its amine salt or its ammonium salt used in the present invention is not a phosphoric acid ester but a carbon atom and a phosphorus atom directly bonded. The phosphonic acid is preferable for the purpose of the present invention because its structure is less likely to be hydrolyzed than a phosphoric acid ester.

The above phosphonic acid derivative has a rust preventive effect and can enhance the anticorrosion property. Examples of the phosphonic acid derivative, its amine salt or its ammonium salt include, for example, Dequest 2000 and Dequest 20.
Examples thereof include those obtained by neutralizing Dayquest 2041 (manufactured by Nippon Monsanto Co., Ltd.) with amines or ammonia.

The acidic catalyst () is (+) 100.
0.1 to 5 parts by weight is added to parts by weight. 0.1
If it is less than 5 parts by weight, the catalytic action is lowered, and curing for a short time or at a low temperature is difficult, and if it exceeds 5 parts by weight, the amount remaining in the film is increased and the water resistance is lowered.

Hereinafter, the composition containing and is referred to as "composition A". In the present invention, composition A (+
+) 100 parts by weight may further contain 10 to 80% by weight of the polyurethane resin emulsion (). When the polyurethane resin emulsion is used in applications where importance is attached to coating film adhesion and bending workability, the above performance cannot be obtained if the polyurethane resin emulsion is less than 10% by weight, and corrosion resistance and lubricity are impaired if it exceeds 80% by weight. More preferably 15-50
% By weight. Hereinafter, the one containing (+++) is referred to as “composition B”.

As the polyurethane resin emulsion, both a forced emulsification type which uses an emulsifier and a self-emulsification type which does not use an emulsifier can be used. In the present invention, it is preferable to use a self-emulsifying type polyurethane resin emulsion since there are no problems such as strength change of the coating due to residual emulsifier and reduction of water resistance. The self-emulsifying type polyurethane resin emulsion is preferable for the present invention because it has a gel structure and the hydration stability of the emulsion is good.

As the polyurethane resin emulsion, various types such as polyether type, polyester type, polycarbonate type and mixed type thereof can be used depending on the kind of raw material. Examples of the polyether-based polyurethane resin emulsions include Superflex 110 (Daiichi Kogyo Seiyaku Co., Ltd.), Superflex F-8438D (Daiichi Kogyo Seiyaku Co., Ltd.) and Hydran HW950 (Dainippon Ink and Chemicals Co., Ltd.). Etc. can be mentioned.

Examples of the above polyester-based polyurethane resin emulsion include Superflex F-
8123D (Daiichi Kogyo Seiyaku Co., Ltd.), Hydran HW91
0 (manufactured by Dainippon Ink and Chemicals), Hydran HW92
0 (manufactured by Dainippon Ink and Chemicals), Hydran HW93
0 (manufactured by Dainippon Ink and Chemicals, Inc.), Hydran HW94
0 (manufactured by Dainippon Ink and Chemicals, Inc.), Hydran HW96
0 (manufactured by Dainippon Ink and Chemicals, Inc.) and the like can be mentioned. Examples of the polycarbonate-based polyurethane resin emulsion include Superflex 460
(Manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Superflex F-812
4D (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Hydran HW935 (manufactured by Dainippon Ink and Chemicals, Inc.), Hydran HW980 (manufactured by Dainippon Ink and Chemicals, Inc.) and the like can be mentioned. These can be used alone or as a mixture of two or more thereof.

The polyurethane resin emulsion preferably has a glass transition temperature (Tg) of 10 to 80 ° C. When the Tg is within this range, desired film strength and adhesion can be obtained in a wide temperature range of 130 to 180 ° C. when the aqueous coating composition of the present invention is formed into a film. A more preferable Tg range is 20 to 80 ° C. In the present invention, a desired Tg can be obtained by mixing the above various polyurethane resin emulsions.

The aqueous coating composition of the present invention is applied as it is or after adding appropriate additives, as a coating composition for paint base, a lubricating anticorrosion coating composition or an automotive anticorrosion coating composition.

In the case of the above-mentioned coating composition for a coating base, the composition A may contain a polyurethane resin emulsion (), if necessary, and a rust preventive pigment, and
At least one kind () of fine particle silica may be appropriately contained. Below (+++) or (+
The one containing +++) is referred to as “composition C”.
It is preferable that the rust preventive pigment has an electric conductivity of 600 μS / cm or less in an aqueous dispersion prepared by dispersing 1 g in 100 g of deionized water. Composition C can be used as an anticorrosive coating composition. It is preferable that 100 parts by weight of the composition A or the composition B of the composition C contains 1 to 40 parts by weight of the rust-preventive pigment and the silica in terms of solid content. If it is less than 1 part by weight, the corrosion resistance will be reduced to 40
If it exceeds the weight part, the effect is saturated in corrosion resistance and the strength and water permeability of the film are reduced, which is not preferable.

Examples of the above-mentioned rust preventive pigment include calcium phosphate (eg, LF Bosei CP-Z manufactured by Kikuchi Dye Company),
Phosphate rust preventive pigments such as zinc phosphate; Molybdate rust preventive pigments such as zinc molybdate (eg, LF Bosei M-PSN manufactured by Kikuchi Dye Co., Mori White 101 manufactured by Honjo Chemical Co.); cyanamide zinc calcium (For example, LF Bosei ZK-S2 manufactured by Kikuchi Dye Co., Ltd.) and the like can be mentioned.

Examples of the rust preventive pigment having a conductivity of more than 600 μS / cm include calcium leadate, silica phosphate, and the like.
Examples thereof include zinc chromate, strontium chromate, and barium metaborate. These not only hinder the water resistance and blister of the coating film, but also impair the stability of the water-soluble resin, and therefore cannot be used in the present invention.
Further, lead-based rust preventive pigments such as basic lead sulfate and cyanamide lead cannot be used in the present invention except for special cases, in view of toxicity.

The silica used in the present invention is in the form of fine particles or a colloid such as a sol, and those commonly used as anticorrosive paints, especially as coating agents for thin film type anticorrosive steel sheets can be used. But the pH of the aqueous dispersion
4 to 9 of dry silica or colloidal silica are preferred. Since most dry silica has an acid point in the acidic region of pH 4 to 5, it tends to lower the pH of the resin aqueous solution, so that the resin does not become water-soluble (becomes a dispersion type) and an aqueous coating. When the composition is set to be weakly alkaline, its storage stability becomes poor, which is not preferable. However, this is not the case when the aqueous coating composition is set to be weakly acidic.

Examples of the wet silica include those stabilized in water in a colloidal state. Examples thereof include Snowtex O (manufactured by Nissan Chemical Industries, Ltd.), Snowtex N (the same), and Adelite AT-20 ( Asahi Denka Kogyo Co., Ltd.),
Adelite AT-30 (same), Adelite AT-40
(Same), Adelite AT-50 (Same), Adelite AT
-20S (same), Adelite AT-30S (same), Adelite AT-20N (same), Adelite AT-20A
(The same), Adelite AT-30A (the same) and the like. Further, examples of the above-mentioned dry silica include those referred to as fumed silica or vapor phase silica, and examples thereof include Aerosil 380 (manufactured by Nippon Aerosil Co., Ltd.), Aerosil 300 (the same), and Aerosil 200.
(The same) can be mentioned.

The silica used in the present invention is preferably colloidal with a phosphoric acid compound, a molybdenum compound, a boric acid compound or the like. The colloidal particles are mainly composed of silica and aluminum silicate,
It is preferable that these have a high purity and do not contain miscellaneous ions. Examples of the dry aluminum silicate include Aerosil MOX170 (manufactured by Nippon Aerosil Co., Ltd.),
Aerosil MOX80 (same), Aerosil COK84
(The same) can be mentioned. Aluminum silicate or the like can be more efficiently colloidalized than silica alone.

The amount of the above-mentioned dry silica or dry aluminum silicate is preferably 50 to 200 parts by weight with respect to the total amount of 1000 parts by weight including water. If the amount is less than 50 parts by weight, the colloidalized particles thus obtained are likely to reaggregate, and the corrosion resistance of the coating film formed by the aqueous coating composition containing the colloidalized particles is deteriorated, which is not preferable. Further, if it exceeds 200 parts by weight, the corrosion resistance of the coating film formed by the aqueous coating composition containing the colloidalized particles thus obtained tends to be deteriorated, which is not preferable. More preferably, it is 100 to 150 parts by weight.

The colloidalization aid, which is the main component of the colloidal particles, may be any compound capable of forming a large anion in an aqueous solution, and may be a phosphoric acid compound such as pyrophosphoric acid, tripolyphosphoric acid or tetrapolyphosphoric acid. Condensed phosphoric acid such as acid, pentapolyphosphoric acid, hexapolyphosphoric acid, heptapolyphosphoric acid, octapolyphosphoric acid, nonapolyphosphoric acid, decapolyphosphoric acid, metaphosphoric acid, trimetaphosphoric acid, hexametaphosphoric acid, ultrapolyphosphoric acid and the like. An ammonium salt etc. can be mentioned.

Although there are these alkali metal salts and alkaline earth metal salts, the incorporation of metal ions has a detrimental effect on the corrosion resistance of the coating film formed by the aqueous coating composition using the obtained colloidalized particles. Exert. That is, when the coating film contains metal ions, it accelerates the permeation of halogen ions (for example, Cl ⁻ ) through the film in a corrosive atmosphere, and also kills the cation exchange ability of silica, resulting in extremely low corrosion resistance. Therefore, the use of alkali metal salts or alkaline earth metal salts is not preferred.

In addition to the above phosphoric acid compounds, molybdic acid compounds such as ammonium molybdate tetrahydrate, boric acid compounds such as ammonium pentaborate and metaboric acid, and silicic acid compounds such as orthosilicic acid. , Metasilicic acid and the like. However,
Although silicic acid is slightly soluble in water, it can be used by dissolving it in an ammonium-based alkaline solution. Further, the sulfur-containing anion is also chemically active with respect to the redox reaction, but can be converted into colloidal form.

The amount of the colloidalization aid added is not particularly limited and may be adjusted according to the particle size of the desired colloidalized particles. For example, the particle size of the colloidalized particles is 500 nm or less. In the case of using silica or aluminum silicate, preferably 2 ×
It is 10 ^{−4 to} 2 × 10 ⁰ mol. If the addition amount is less than 2 × 10 ⁻⁴ mol, the obtained colloidalized particles are immediately restored to the network structure particles due to aggregation and coarsen, which is not preferable. On the other hand, if it exceeds 2 × 10 ⁰ mol, the corrosion resistance of the coating film formed by the aqueous coating composition containing the colloidalized particles obtained thereby tends to decrease, which is not preferable. More preferably 2 × 10 ⁻³ to 2
The range of × 10 ^-2 mol is preferable.

The water as the main component of the colloidal particles is preferably ion-exchanged water, pure water or the like having a small amount of impurities. The amount of water is preferably 950 to 800 parts by weight with respect to the total amount of 1000 parts by weight of dry silica or dry aluminum silicate and water.

The colloidalized particles thus obtained can be granulated to a desired particle size by adjusting the amount of the colloidalization aid added. For example, when it is added to a water-based coating composition for an organic film of a highly anticorrosive precoated steel sheet, the thickness is preferably 500 nm or less, more preferably 150 to 250 nm.

When the water-based coating composition of the present invention is used as a lubricating and anticorrosive coating composition, the composition C100 is used.
It is preferable to add 3 to 15 parts by weight of wax in terms of solid content to parts by weight (hereinafter referred to as "composition D").
The wax is not particularly limited as long as it can be dispersed in water, and examples thereof include paraffin wax, microcrystalline wax, and polyethylene wax (examples of polyethylene wax having an average molecular weight of 2000 to 8000; Disparlon SE210-15T manufactured by Kusumoto Kasei Co., Ltd.). , Dispallon SE480-10T manufactured by the same company, Chemipearl WF640 manufactured by Mitsui Oil Co., Ltd., Chemipearl W700 manufactured by the same company), polypropylene wax, polybutene wax and the like. In addition to the above wax, it is possible to use polytetrafluoroethylene, other fluorine resins, fluorine-based solid lubricants such as carbon fluoride, graphite, metal soap, and the like, which can be mixed in the water-based composition.

When the aqueous coating composition of the present invention is used as an anticorrosive coating composition for automobiles, the composition D1 is used.
Melamine cyanurate compound 0.05-
It is preferable to contain 25 parts by weight. When the amount of melamine cyanurate added is less than 0.05 parts by weight, the effect of preventing the adhesion failure at the interface of the base metal due to the electrical load during electrodeposition coating disappears as described later, and exceeds 25 parts by weight. If so, the uniformity and denseness of the film are lost, and in the case of thin film coating, the barrier effect is hindered, which is not preferable.

The above melamine cyanurate is a compound having an isocyanur ring-containing planar structure, and has the formula (C ₆ H ₉
Is represented by N ₉ O ₃₎ n, for example, 2,4,6-triamino-1,3,5-triazine (hereinafter "melamine"),
An equimolar addition compound with 2,4,6-trihydroxy-1,3,5-triazine (hereinafter referred to as “cyanuric acid”) and its tautomer, and in the solid state, melamine molecule and cyanuric acid molecule are It is presumed that they are adjacent to each other in a weak hydrogen bond state alternately and form crystals having the following planar structure.

[0056]

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In the formula, ● is carbon, ○ is nitrogen, ◎ is oxygen,
Represents hydrogen, M represents a melamine molecule, and C represents a cyanuric acid molecule. Further, the three-dimensional structure is presumed to be a so-called graphite type, which is a stacked structure having a constant surface spacing as described below.

[0058]

[Chemical 3]

In the formula, M and C are the same as above. Examples of these melamine cyanurate compounds include Japanese Examined Patent Publication No. 60-338.
The manufacturing method is described in Japanese Patent No. 50, and MC series (MC-FW, MC-PW, MC-BW, manufactured by Nissan Chemical Industries, Ltd.
MC-UW, MC-420, MC-520, MC-60
0) and the like. It is described in JP-A-3-28277 that the melamine cyanurate is contained in a clear layer to exhibit the same pearly luster as that of mica coating in metallic coating of automobiles and the like, but it is not related to the present invention. is there.

The above melamine cyanurate compound has good acid resistance and alkali resistance, and is stable in the range of pH 1 to 14 without chemical change. This means that under cationic electrodeposition coating, the bottom of the electrodeposition coating film is exposed to about pH 12. Therefore, the rust preventive coating composition for automobiles containing the melamine cyanurate compound of the present invention is subjected to electrical load during electrodeposition. There is an effect of preventing the adhesion failure at the interface of the base metal due to.

The melamine cyanurate compound is poorly soluble in water and has heat resistance. Further, it does not dissolve in an organic solvent used for general paints, but only slightly dissolves in dimethyl sulfoxide at 0.011 g / 100 ml at 70 ° C. This does not dissolve in water penetrating under the coating film during electrodeposition coating and does not become a factor for inhibiting electrodeposition.

The following pigments and additives may be further added to the aqueous coating composition of the present invention as other components within the range not inconsistent with the constitution of the present invention.

As the color pigment, for example, titanium oxide,
Phthalocyanine blue, phthalocyanine green, quinacridone, indanthrone, perylene, anthrapyrimidine, carbon black, benzimidazolane, graphite,
Examples thereof include yellow iron oxide and red iron oxide. Examples of extender pigments include calcium carbonate, gypsum, clay, talc and the like. The content of the pigment is preferably set in the range of 0.5 to 30 parts by weight with respect to 100 parts by weight of the resin solid content of the aqueous coating composition.

Examples of the solvent that can be used in the present invention include water; alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, 2-butyl alcohol, benzyl alcohol, cyclohexanol; Examples thereof include ketone-based hydrophilic organic solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, and diacetone alcohol, and mixtures thereof.

The amount of the above solvent added is in the range of 50 to 80% by weight in the case of water and 0 to 80% by weight in the case of a hydrophilic organic solvent in the aqueous coating composition. The amount is adjusted in the range of 20 to 50% by weight based on the resin solid content of the aqueous coating composition at the time of production, and 10 to 20% by weight based on the resin solid content of the aqueous coating composition at the time of coating. It is preferable.

Further, as the additives that can be used in the present invention, for example, antifoaming agents, leveling agents, anti-repellent agents, gloss improvers, anti-settling agents, wetting agents (surfactants), lubricants, antiseptics. Agents, dustproofing agents and the like.

For mixing the respective components, an apparatus such as a paint shaker, a dispa, a ball mill, a sand grind mill, a kneader, a dissolver or the like which is commonly used in paint production is used, and the viscosity is adjusted by using water as a solvent. On this occasion,
A hydrophilic organic solvent can be used in combination with water as long as the emulsion is not destroyed.

The addition of colloidalized particles to the aqueous coating composition is carried out either during the manufacturing process of the paint (pre-addition) or to the finished paint (post-addition). Addition of the colloidalized particles to the aqueous coating composition is carried out using a dispersion mixer such as the paint shaker, disper, ball mill, sand grind mill, kneader and dissolver.

Further, the metal plate to be coated can be pretreated before coating in order to prevent the material from rusting and improve the adhesion of the coating, for example, acid or alkali. Examples include degreasing treatment such as washing.

When the aqueous coating composition of the present invention is used as a coating base treatment for a steel sheet, the coating method is as follows: composition A, composition B or composition C, and the nonvolatile residue is 1
It can be applied to a degreased steel surface diluted with water to 0 to 20%. The pH of the above composition is 4.0 to
9.0 is preferable. As the coating method, an ordinary method such as dipping, spraying, showering, or rolling can be used. The dry film thickness is preferably 1 to 10 μm. 1
If it is less than μm, the uniformity of coating is impaired and pinholes are generated, and corrosion is likely to occur from there, and if it exceeds 10 μm, strain is likely to occur and it does not contribute to wet adhesion. More preferably, it is 2 to 5 μm. In addition, a rust preventive agent such as inhibitor (Irgacore, manufactured by Ciba-Geigy) is added to the above composition;
A chelating agent such as phytic acid and gallic acid may be added.

When the aqueous coating composition of the present invention is used as a surface treatment for coating a galvanized surface, the composition A is used.
Alternatively, it is used by adding the above silica to the composition B. In galvanized painting, a primer containing an anticorrosive pigment is usually applied on the surface of the coating, so an antirust pigment is not necessary for this undercoating. A rust preventive pigment may be added to the film of the invention.

As the above-mentioned silica, dry silica, wet silica and the like are used, but dry silica having few miscellaneous ions such as alkali metals is preferable. The addition amount of the silica is preferably 1 to 20 parts by weight with respect to 100 parts by weight of the resin solid content. In addition, when it is used in fields such as color galvanized iron and household appliances where bending is important, improving adhesion,
A polyurethane resin emulsion may be added to the film for the purpose of preventing peeling during bending and improving wet adhesion.
As the coating method, the above aqueous coating composition may be diluted to an appropriate concentration and then coated on a galvanized surface by a roll coater or the like so that the dry film thickness is 1 to 5 μm. When the film thickness is less than 1 μm, pinholes are generated and the corrosion resistance and wet adhesion are deteriorated. When the film thickness exceeds 5 μm, the film peels off during bending and the coating film adhesion is impaired, which is not preferable.

After the metal material coated with the aqueous coating composition of the present invention (eg, galvanized steel sheet) is bent or deep-drawn, the coating film can be further coated, if necessary. The coating may be performed by undercoating (primer coat) and then topcoating, or simply by topcoating (topcoat). In order to improve the anticorrosion property, on the formed coating film,
It is desirable to apply an undercoat (primer coat). The primer coat has a function of protecting the material from corrosive action and imparting adhesion to the surface of the metal plate, the surface treatment film and the top coat film. The thickness of the undercoat coating film is usually 1 to 7 μm when dried. The baking is carried out within a short time under the conditions of the optimum temperature and time for the coating resin used.

The preferred coating film for the top coating is 7 to 50 μm (when dried). If this coating film has a thickness of less than 7 μm, the undercoat material cannot be concealed due to poor coloring power, and if it exceeds 50 μm, there is a risk of pinhole formation during baking at a high temperature for a short time. Absent. Optimum conditions for baking temperature and time are set according to the topcoat paint used.

As a coating system to be combined with the coating film formed by the aqueous coating composition of the present invention,
The type of resin is not limited to the above, and may be any of organic solvent type, water type, and powder type. The coating method of the above water-based coating composition is not particularly limited, and a usual coating method such as air spray coating, airless coating, electrostatic coating or the like can be used.

As a method for applying the lubricating and anticorrosive coating composition of the present invention, the composition is diluted with water to a suitable concentration for application, and a method such as roll coating is used. Can be applied. If the film thickness is less than 1 μm, pinholes are generated and the corrosion resistance and wet adhesion are deteriorated. If the film thickness exceeds 5 μm, the film peels off during processing to reduce brushing, which is not preferable.

The anticorrosion coating composition for automobiles of the present invention is applied to a galvanized steel sheet for automobiles and dried. Further, a cation or anion electrodeposition coating is applied thereon so that the dry film thickness is 15 to 40 μm, and further, if necessary,
An alkyd resin, polyester resin, or acrylic resin-based intermediate coating material may be applied so that the dry film thickness is 20 to 60 μm, and then an acrylic resin, polyester resin, or fluororesin-based automotive topcoating material may be used.

[0078]

In the aqueous coating composition of the present invention, hydration stability and reactivity with an oxazoline compound can be maintained by limiting the acid value based on the carboxylic acid of the phosphoric acid modified product of the bisphenol type epoxy resin. . Further, the acid value based on the phosphoric acid group of the phosphoric acid modified product of the bisphenol type epoxy resin maintains the hydration stability and the adhesiveness with the metal substrate, and realizes a strongly adhered film. It is possible to maintain excellent workability (resistance to peeling of processed part). Furthermore, by using an oxazoline compound, in the case of a phosphoric acid-modified product of a bisphenol type epoxy resin having a carboxyl group, it can be crosslinked by reacting with the carboxyl group, and a tough film can be formed even by baking for a short time. This makes it possible to exhibit corrosion resistance and high workability. When the melamine resin and the oxazoline compound are used in combination, the melamine resin is reactively cured with the hydroxyl group of the phosphoric acid modified product of the bisphenol type epoxy resin, and when the phosphoric acid modified product of the bisphenol type epoxy resin has a carboxyl group. As described above, the oxazoline compound can be reacted and cured with the carboxyl group thereof to form a film that is firmly adhered. Further, by using the polyurethane resin emulsion in combination, the adhesiveness becomes good, and good characteristics as the top coating material can be obtained.

[0079]

EXAMPLES The present invention will be described in more detail below with reference to resin production examples and examples, but the present invention is not limited to these.

Reference Example 1 94 parts of carboxylic acid, 405 parts of 37% formalin and 211 parts of an aqueous solution of sodium hydroxide were mixed and reacted at 50 ° C. for 2 hours. After neutralization with hydrochloric acid, ethyl acetate / n-butanol =
Extraction was performed with a 1/1 mixed solvent to obtain a resol-type phenol resin solution having a solid content of 80%.

Reference Example 2 A raw material having the following composition was charged in a container equipped with a stirrer, a temperature controller and a decanter, and heated with stirring. Soybean fatty acid 34 parts by weight Trimethylolpropane 34 parts by weight Trimellitic anhydride 9 parts by weight Isophthalic acid 25 parts by weight Xylene 1 part by weight Dibutyltin oxide 0.5 parts by weight Water produced by reaction is azeotropically distilled with xylene. It was removed, and heating was continued until the acid value became 39 and the hydroxyl value became 140 to terminate the reaction. The obtained resin was diluted with butyl cellosolve to a nonvolatile content of 70% by weight to obtain an alkyd resin varnish. This resin varnish is theoretically 100% neutralized with triethylamine, and the nonvolatile content is 40% with deionized water.
A water-soluble alkyd resin varnish [1] was obtained by adjusting the content to be wt%. The substance had a substantial acid value of 33.

Reference Example 3 A raw material having the following composition was charged in a container equipped with a stirrer, a temperature controller and a decanter, and heated with stirring. Soybean fatty acid 30 parts by weight Trimethylolpropane 17 parts by weight Fopentyl glycol 13 parts by weight Trimellitic anhydride 7 parts by weight Isophthalic acid 32 parts by weight Xylene 1 part by weight Dibutyltin oxide 0.02 parts by weight Water generated as the reaction proceeds It was removed by azeotropic distillation with xylene, and heating was continued until the acid value became 30 and the hydroxyl value became 60, and the reaction was terminated. The obtained resin was diluted with butyl cellosolve to a nonvolatile content of 70% by weight to obtain an alkyd resin varnish. This resin varnish is theoretically 100% neutralized with triethylamine, and the nonvolatile content is 40% with deionized water.
A water-soluble alkyd resin varnish [2] was obtained by adjusting the content to be wt%.

Examples 1 to 7 and Comparative Examples 1 to 3 The compositions were mixed at the compounding ratios shown in Table 1 to obtain aqueous coating compositions. In Table 1, XU-71899.00 is
Dow Chemical Japan's bisphenol-type epoxy resin phosphoric acid modified product (acid value = 10, dimethylethanolamine (DMEA) neutralized 100%), phosphoric acid ester modified epoxy resin acrylic graft polymer are manufactured by Tohto Kasei Co., Ltd. , Cymel 328 is manufactured by Mitsui Cyanamid Co., Ltd., iminomethylol melamine, and Cymel 303 is manufactured by Mitsui Cyanamid Co., Ltd., methoxymelamine resin, Cymel 112.
3 is a benzoguanamine resin manufactured by Mitsui Cyanamid Co.,
The aqueous phenolic resin was synthesized according to Reference Example 1, the sulfonic acid-based catalyst was Catalyst 500, manufactured by Mitsui Cyanamide, the acidic phosphoric acid-based catalyst was ammonium dihydrogen phosphate, and the phosphonic acid-based catalyst was Nippon Monsanto. Dequest 2041 (ammonia neutralized product of ethylenediaminetetra (methylenesulfonic acid)) and Hydran 935 manufactured by Dainippon Ink and Chemicals, Inc. represent a polyurethane resin emulsion manufactured by Dainippon Ink and Chemicals.

Evaluation method (1) Thin film corrosion resistance Examples 1 to 7 and Comparative Examples 1 to 1 obtained as described above.
The water-based coating composition of No. 3 was diluted with water to a nonvolatile content of 20% and degreased (JIS G3141).
SPCC-SD) with a bar coater to dry film thickness 2-3μ
It was applied so as to have a thickness of m and dried at an ultimate plate temperature of 130 ° C. for 10 minutes to obtain a test piece. In the salt spray test, the time required for the test piece to reach a rusting state of 0.3% in FIG. 1 (ASTM, D610-68 rust area determination chart) was measured.

(2) MEK rubbing test The dried test piece was treated with methyl ethyl ketone (ME
The gauze dipped in K) was rubbed against the coated surface while being pressed under a load of 300 g, and the number of times until the film was broken was measured. ◎: 200 times or more ○: 100 to 200 times △: 10 to 100 times ×: 0 to 10 times

(3) Topcoat Water Resistance, Topcoat Corrosion Resistance Odeselect 500 (alkyd melamine-based water-based paint manufactured by Nippon Paint Co., Ltd.) was applied to the above-mentioned test pieces as a topcoat so that the dry film thickness was 25 to 30 μm, and at 140 ° C. 20
Minute baking was performed to obtain a sample. (I) Topcoat Water Resistance After dipping the above sample in tap water at 40 ° C. for 120 hours, a coating film blister (blister) as shown in FIG. 2 was evaluated. No. 2 in FIG. 2, 4, 6, and 8 represent the size of the blisters, and F, M, MD, and D represent the density of each blister. ◯: No blister Δ: Blister F (ASTM density standard) ×: Blister M (ASTM density standard) XX: Blister MD, D (ASTM density standard) (ii) Topcoat corrosion resistance The above sample was degreased and a sharp knife (cutter) was used. With a knife), scratches were made to reach the substrate diagonally, and after being subjected to a salt spray test for 100 hours, the surface water was wiped off and dried, and the adhesive tape was pressed along the cut and rapidly peeled off. The width (mm) of the coating film was measured. It is expressed by the width of one side peeled from the cut portion. The evaluation results are shown in Table 1.

Example 8 Formulation for application to a general industrial coating base treatment film XQR-711-1352.60 (a phosphoric acid modified product of a bisphenol type epoxy resin manufactured by Dow Chemical Japan) was added to dimethylethanolamine (DMEA). After neutralizing with () (neutralization ratio 70%), water was added to emulsify (acid value = 1
2, 100 parts by weight of average weight molecular weight of about 10,000),
40 parts by weight of iminomethylol-based melamine (Cymel 327, manufactured by Mitsui Cyanamid), Dequest 2041
(Nippon Monsanto Co., Ltd., ammonia neutralization) 0.5 part by weight, Hydran HW960 (manufactured by Dainippon Ink and Chemicals, Inc.) 10 parts by weight, colloidal silica (Adelite AT2)
0N, manufactured by Asahi Denka Kogyo Co., Ltd.) 10 parts by weight, anti-corrosion pigment (molybdic acid type LF Bosei M-PSN, manufactured by Kikuchi dye company) 2 parts by weight, anti-corrosion agent (Irgacoa 252, manufactured by Ciba Geigy)
5 parts by weight were sequentially added and uniformly mixed with a disper. Dilute this to a solid content of 20%, and add DME
The pH was adjusted to 6.5 by adjusting A and phosphoric acid to obtain a water-based anticorrosive coating composition for coating base. The rust preventive pigment (LF Bosei M-PSN, manufactured by Kikuchi Dye Co., Ltd.) was beaded on an SG mill using an alkyd resin varnish [2] (Reference Example 3, acid value 30, hydroxyl group 60) in order to stabilize the dispersion. Dispersed pigment paste (resin: pigment = 7: 2)
0) was used. The Irga core 252 was neutralized with ammonia to prepare a water paste having an appropriate solid content, and used the required amount. The above composition was applied to a degreased steel plate (JIS G 3141
SPCC-SD) was subjected to a base treatment, and Olga Select 120 White (melamine alkyd solvent-based paint) was further applied so that the dry film thickness was 25 to 30 μm to obtain a coated steel sheet.

Example 9 Formulation for Application to Coating Type Undercoating Film for Color Steel Sheet XQR-711-1352.60 (manufactured by Dow Chemical Japan, phosphoric acid modified product of bisphenol type epoxy resin, DMEA neutralized ( Neutralization rate 50%) Emulsified product, acid value = 12, average weight molecular weight about 10,000) 100 parts by weight, iminomethylol melamine (Cymel 328, manufactured by Mitsui Cyanamide Co., Ltd.) 30 parts by weight, aqueous phenolic resin (SHONOL N- 2, Showa High Polymer Co., Ltd.) 20 parts by weight,
Dequest 2010 (manufactured by Nippon Monsanto Co., Ltd., ammonia neutralization) 0.5 part by weight, Superflex F8124
D (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 20 parts by weight, silica (Aerosil 300, manufactured by Nippon Aerosil Co., Ltd.) 30 parts by weight, rust preventive pigment (phosphomolybdic acid LF Bosei DM300W, manufactured by Kikuchi dye company) 5 parts by weight, rust preventive 5 parts by weight of the agent (IRGACORE 252, manufactured by Ciba Geigy) was blended in the same manner as in Example 8 and diluted so that the solid content was 20%, and the pH was adjusted to 4.5.
An aqueous coating composition for a paint base was obtained. Further, the above composition was applied to a hot-dip galvanized steel sheet skin pass non-spangle agent (without chromate treatment) and subjected to a base treatment, and then Superlac DIF-P01 primer was applied as a primer and Nippe Supercoat 300HQ was applied as a topcoat. , A coated steel plate was obtained.

Example 10 Formulation for Application to Lubrication and Anticorrosion Coating Composition XQR-711-1352.60 (manufactured by Dow Chemical Japan, phosphoric acid modified product of bisphenol type epoxy resin, DMEA neutralized (neutralized 100%) emulsified,
Acid value = 12, average weight molecular weight about 10,000) 100 parts by weight, iminomethylol melamine (Cymel 328, manufactured by Mitsui Cyanamide Co., Ltd.) 30 parts by weight, Epocros K-10
50E (manufactured by Nippon Shokubai Chemical Co., Ltd.), 2 parts by weight of ammonium hydrogen phosphate, 20 parts by weight of Hydran HW940 (manufactured by Dainippon Ink and Chemicals, Inc.), 15 parts by weight of colloidal silica (Adelite AT20N, manufactured by Asahi Denka Co., Ltd.), 5 parts by weight of Chemipearl W700 (manufactured by Mitsui Petrochemical Industry Co., Ltd.) and 5 parts by weight of a rust preventive agent (IRGACORE 252, manufactured by Ciba Geigy) were blended in the same manner as in Example 8 and diluted so that the solid content was 20%. The pH was adjusted to 8.0 to obtain a lubricating anticorrosive coating composition. Electrogalvanized steel sheet (without chromate treatment) coated with the above composition, and Olga Select 100 White (melamine alkyd water-based paint)
Was applied to give a dry film thickness of 25 to 30 μm to obtain a coated steel sheet.

Example 11 Formulation for Application to Automotive Anticorrosion Coating Composition XQR-711-1352.60 (manufactured by Dow Chemical Japan, phosphoric acid modified product of bisphenol type epoxy resin, DMEA neutralized (neutralized 90%) Emulsified product, acid value = 12, average weight molecular weight about 10,000) 100 parts by weight, iminomethylol melamine (Cymel 328, manufactured by Mitsui Cyanamid Co.) 30 parts by weight, ammonium dihydrogen phosphate 2 parts by weight, hydrane 20 parts by weight of HW935 (manufactured by Dainippon Ink and Chemicals, Inc.), Aerosil MOX170
15 parts by weight of colloidal (manufactured by Nippon Aerosil Co., Ltd.) with boric acid, 5 parts by weight of Chemipearl WF640 (manufactured by Mitsui Petrochemical Co., Ltd.), melamine cyanurate MC-42
5 parts by weight of 0 (manufactured by Nissan Chemical Industries, Ltd.) were mixed in the same manner as in Example 8, diluted to a solid content of 20%, and the pH was adjusted to 6.
5, to obtain an automobile anticorrosion coating composition. The above composition was applied to a zinc-nickel electroplated steel sheet (with chromate treatment) and treated, and a cationic electrodeposition coating power top U2550 was further applied to give a dry film thickness of 20 to 25 μm.
It was applied so as to obtain m, and a coated steel plate was obtained.

Comparative Example 4 A coated steel sheet was obtained by applying the same coating as in Example 8 using a steel sheet without a base treatment. Comparative Example 5 What was treated with zinc phosphate (surfdyne 1000)
The same coating as in Example 8 was performed to obtain a coated steel sheet. Comparative Example 6 Coating type dichromate treating agent NRC-300 to CrO ₃
And replace it with polyacrylic emulsion EM110
0 (made by Nippon Paint Co., Ltd.) 10 weight, Aerosil 300
10% by weight of the composition was applied and the same coating as in Example 9 was performed to obtain a coated steel sheet. Comparative Example 7 Water-soluble alkyd resin varnish [1] (reference example 2, acid value = instead of phosphoric acid modified product of bisphenol type epoxy resin)
39, hydroxy value = 140) was performed in the same manner as in Example 10 to obtain a coated steel sheet.

Comparative Example 8 25 parts by weight of Dick Fine EN0270 (manufactured by Dainippon Ink and Chemicals, Inc., self-emulsifying epoxy resin), Epocros K-1020E (manufactured by Nippon Shokubai Co., Ltd.), UE1101 (self-emulsifying polyurethane emulsion resin) 75 parts by weight Department,
Snowtex N (manufactured by Nissan Chemical Industries, water-dispersed silica)
25 parts by weight and 3 parts by weight of melamine cyanurate MC-600 (manufactured by Nissan Chemical Industries, Ltd.) were mixed to obtain an automobile anticorrosion coating composition, and a coated steel sheet was obtained in the same manner as in Example 11.

Evaluation Method Each substrate was coated with a bar coater so that the dry film thickness was 2 to 4 μm, and dried at 130 ° C. for 5 minutes. (I) Corrosion resistance of thin film A test was conducted only on the treated film without applying a top coat in the salt spray test, and the time until 0.3% of rust generation occurred in Fig. 1 (Rust area determination chart according to ASTM, D610-68). Was evaluated as follows. When the substrate is a steel sheet (Example 8 and Comparative Example 4) ◯: Rusted in 100 hours Δ: Rusted in 50 hours X: Rusted within 1 hour XX: Rusted within 10 minutes Substrate was galvanized steel sheet (Examples 9 to 11 and Comparative Examples 5 to 8) ◯: No white rust was generated for 500 hours or more. Δ: White rust was generated within 100 hours. ×: White rust was generated within 10 hours. XX: White within 1 hour. Rust generation (ii) MEK Rabinck test The same as above.

(Iii) Alkali resistance After immersion in Surf Cleaner 53S (manufactured by Nippon Paint Co., Ltd.), which is an alkaline degreasing agent, at 45 ° C. for 10 minutes, the state of the coated surface was observed and evaluated according to the following evaluation criteria. ⊚: No abnormality ○: Very little whitening △: 50% whitening ×: Full whitening with elution

(Iv) Workability: Cylindrical drawing test The resin coated surface was processed with the die side, and the coating film peeling powder adhering to the die at that time was sampled with cellophane tape and evaluated from that degree. For the powdering, the narrowed portion was peeled off with a tape, and the degree of peeled powder was evaluated. The press conditions at this time were as follows. Wrinkle suppression pressure: 3 tons Punch diameter: 50 mmφ Blank diameter: 95 mmφ Drawing ratio: 1.92 Drawing speed: 300 mm / sec

The appearance was observed and evaluated according to the following evaluation criteria. ⊚: No adhesion to the die ◯: Some adhesion to the die Δ: Adhesion to the die was between ○ and × ×: A large amount of adhesion to the die The powdering was evaluated according to the following evaluation criteria. ◎: No peeling powder ○: Some peeling powder △: Intermediate between ○ and × ×: A large amount of peeling powder

(V) Topcoat Suitability The coated steel sheet was baked at an ultimate plate temperature of 180 ° C. × 20 ° C., Olga Select 120 White (manufactured by Nippon Paint Co., Ltd.) was spray coated, and baked at 130 ° C. for 15 minutes. After 1 day of coating, 100 pieces of 2 mm wide Gobang are put in the coating film, extruded from the back side of the 3 mm coated plate with an Erichsen tester, peeled off with a commercially available adhesive tape, and the adhesiveness ( It was displayed as (number) / 100. The dry film thickness of the topcoat was 30 ± 3 μm.

(Vi) Topcoat water resistance For Example 8 and Comparative Examples 4 and 5, 120 hours × 40.
C, 240 for Examples 9-11 and Comparative Examples 6-8.
After immersing in tap water at ℃ × 40 ℃, coating film blister (blister) as shown in Figure 2 was evaluated. In FIG. 2, N
o. 2, 4, 6, and 8 represent the size of the blisters, F,
M, MD, and D represent the density according to the size of each blister. ◯: No blister Δ: Blister F (ASTM density standard) X: Blister M (ASTM density standard) XX: Blister MD, D (ASTM density standard)

(Vii) Topcoat Corrosion Resistance According to JIS 2371, a salt spray test was conducted for the time shown in Table 2 to observe rust on the coated surface, and evaluated according to the following evaluation criteria. For the galvanizing system (Examples 9 to 11 and Comparative Examples 5 to 8), the flat surface corrosion resistance was performed. ◎: No abnormality ○: Some white rust △: White rust on half of the coated surface ×: White rust on the entire surface For steel plates (Example 8 and Comparative Example 4),
7 and Comparative Examples 1 to 3 were performed in the same manner as the topcoat corrosion resistance (cut portion corrosion resistance). ⊚: No peeling ◯: Peeling 2 mm or less Δ: Peeling 2 to 5 mm ×: Peeling 5 mm or more Each evaluation result is shown in Table 2.

[0100]

[Table 1]

[0101]

[Table 2]

[0102]

Since the aqueous coating composition of the present invention has the above composition, when used as an aqueous coating composition for a coating base instead of the phosphate treatment, it realizes sludge-less and space saving of chemical conversion treatment, and waste liquid. Processing can also be unnecessary. Further, by adding wax, melamine cyanurate, etc. to the above composition and using it as a lubricating anticorrosive coating composition and an anticorrosive coating composition for automobiles, chromate treatment of the coating base is unnecessary, corrosion resistance and water resistance. It is possible to obtain a coated steel sheet which is excellent in, for example, and can maintain high workability.

[Brief description of drawings]

FIG. 1 is a diagram of evaluation of surface rust occurrence state according to ASTM, D610-68.

FIG. 2 is a diagram of blister evaluation.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area C09D 5/08 PPY PQE

Claims (6)

[Claims] 1. 100 parts by weight of a phosphoric acid modified product of a bisphenol type epoxy resin having an acid value of 5 to 35 by a phosphoric acid group, an oxazoline compound, a phenol resin, and melamine having a curing start temperature of 140 ° C. or lower. A composition comprising 10 to 500 parts by weight of at least one selected from the group consisting of resins, a benzenesulfonic acid derivative, an amine salt and an ammonium salt thereof, a naphthalenesulfonic acid derivative, an amine salt and an ammonium salt thereof. 0.1 to 5% by weight of the entire composition of an acidic catalyst comprising at least one selected from the group consisting of an amine salt and an ammonium salt of an acidic phosphoric acid, a phosphonic acid derivative, an amine salt thereof and an ammonium salt thereof. An aqueous coating composition comprising: 2. The melamine resin having a curing start temperature of 140 ° C. or lower is at least one selected from the group consisting of imino melamine resins, iminomethylol melamine resins and methylol melamine resins. Aqueous coating composition. 3. An aqueous coating composition comprising 100 parts by weight of the aqueous coating composition according to claim 1 or 2 and 10 to 80 parts by weight of a polyurethane resin emulsion. 4. 100 parts by weight of the aqueous coating composition according to claim 1, 2 or 3 contains 1 to 40 parts by weight of at least one of a rust preventive pigment having a conductivity of 600 μS / cm or less and fine particle silica. A rust-preventive coating composition comprising: 5. A lubricating anticorrosion coating composition comprising 100 parts by weight of the anticorrosion coating composition according to claim 4 and 3 to 15 parts by weight of a wax. 6. The lubricating rust-preventive coating composition according to claim 5 is added with 100 parts by weight of the melamine cyanurate compound.
An anticorrosive coating composition for automobiles, characterized by containing 05 to 25 parts by weight.