JP6744813B2 - Paint composition - Google Patents

Description

The present invention relates to a coating material for steel plates, and more particularly to a coating material suitable for coating non-ferrous metal surfaces such as galvanized steel plates.

It is said that the zinc-plated steel sheet whose surface is galvanized has excellent corrosion resistance and therefore has a durability of 50 years. However, since it actually deteriorates partially over 20 years, it will take 10 to 15 years. Repainting is performed at intervals.
The surface of the portion that has deteriorated with time is subjected to a keeling treatment and repaired with an epoxy resin-containing anticorrosion coating (Patent Document 1).

Patent Document 1 discloses a modified epoxy resin coating containing (a) an epoxy resin, (b) a polyamine compound, and (c) a phenol-modified hydrocarbon resin having a highly reactive phenolic hydroxyl group having a hydroxyl value of 50 to 100 mgKOH/g. It is disclosed that it is possible to form a coating film having excellent adhesion to a galvanized steel sheet.

However, such anticorrosive paints for galvanized steel sheets often contain a solvent having a high resin solubility such as xylene, and weak solvent-based paints have been found to have excellent adhesion to galvanized steel sheets. It has not been.

Japanese Patent Laid-Open No. 2000-144044

Conventional weak solvent-based anticorrosion coatings do not have sufficient adhesion to galvanized steel sheets, and especially in anticorrosion coatings for repairs, the degree of deterioration differs depending on the part of the galvanized steel sheet. In the case of galvanized steel sheet, the difference in adhesion partially appears, and a weak solvent-based paint having excellent adhesion to the galvanized steel sheet itself has been demanded.

It is an object of the present invention to provide a weak solvent-based anticorrosive paint capable of forming a coating film excellent in adhesion to a steel plate, particularly a galvanized steel plate, and having good anticorrosion property.

The present inventors have paid attention to a urethane-modified amine compound having a specific structure that dissolves in a weak solvent, and have completed the present invention.

(1) A two-component curing type epoxy resin coating composition containing a main agent and a curing agent,
The base resin contains at least a solvent A having a mixed aniline point or an aniline point in the range of 12 to 70° C. defined by JIS K 2256, and an epoxy resin component B soluble in the solvent A. Component B contains an epoxy resin having two or more epoxy groups in the molecule,
A coating composition in which the curing agent contains a urethane-modified amine compound C soluble in the solvent A.

（式中、Ｒ¹はヒドロキシル基を有するケチミンおよび／またはエナミンの前記ヒドロキシル基とイソシアネート基とを反応させ、ついで加水分解することによって形成される基に含まれる、Ｈ_２Ｎ−基と−Ｏ−Ｃ（＝Ｏ）−ＮＨ基との間に介在する基を表し、Ｒ²は分子量が５００〜１００００であるポリアルキレンエーテルポリオールが有する２つのヒドロキシル基とイソシアネート基とを反応させて得られる基に含まれる、２つの−Ｏ−Ｃ（＝Ｏ）−ＮＨ基の間に介在する基を表し、ｎは０〜１を表す。） (2) The coating composition as described in 1 above, wherein the urethane-modified amine compound C contains a compound represented by the following structure (1).

(In the formula, R ¹ is a group formed by reacting the hydroxyl group of ketimine and/or enamine having a hydroxyl group with an isocyanate group, and then hydrolyzing the resulting H ₂ N— group and —O -C (= O) represents an intervening group between the -NH group, R ² is a group having a molecular weight obtained by reacting the two hydroxyl groups and isocyanate groups of the polyalkylene ether polyol is 500 to 10000 Which represents a group interposed between two —O—C(═O)—NH groups contained in, and n represents 0 to 1.)

(3) At least one of the main component or the curing agent contains a pigment component D, the pigment component D contains a rust preventive pigment, and the rust preventive pigment is a borate and a phosphate. The coating composition described.

(4) The coating composition according to any one of 1 to 3 above, wherein the mass ratio of the pigment component D and the resin component (the total of the epoxy resin B and the urethane modified amine compound C) is 80/20 to 50/50. ..
(5) The coating composition according to any one of 1 to 4 above, which is used for galvanized steel sheet.

(6) A coating method using a two-component curing type epoxy resin coating composition containing a main agent and a curing agent, wherein the main agent has at least a mixed aniline point or an aniline point of 12 to 70° C. defined in JIS K 2256. The solvent A in the range and an epoxy resin component B soluble in the solvent A, the epoxy resin component B contains an epoxy resin having two or more epoxy groups in the molecule, and the curing agent is A coating method using a coating composition containing a urethane-modified amine compound C soluble in a solvent A.

(7) A coated product of a two-component curing type epoxy resin coating composition containing a main agent and a curing agent, wherein the main agent has at least a mixed aniline point or an aniline point of 12 to 70° C. defined in JIS K 2256. The solvent A in the range and an epoxy resin component B soluble in the solvent A, the epoxy resin component B contains an epoxy resin having two or more epoxy groups in the molecule, and the curing agent is A coated article comprising a coating composition containing a urethane-modified amine compound C soluble in a solvent A.

According to the present invention, it is possible to provide an anticorrosion paint which has excellent adhesion to a steel plate, particularly a galvanized steel plate, and can form a coating film having good anticorrosion properties.

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.
The coating composition of the present invention is a two-component curable epoxy resin coating composition containing a main agent and a curing agent, wherein the main agent has at least a mixed aniline point or an aniline point of 12 to 70° C. defined in JIS K 2256. In the range of A and an epoxy resin component B soluble in the solvent A, the epoxy resin component B contains an epoxy resin having two or more epoxy groups in the molecule, the curing agent, A urethane-modified amine compound C soluble in the solvent A is contained.

<Solvent A>
The solvent of the present invention is characterized in that the mixed aniline point or aniline point defined in JIS K 2256 is in the range of 12 to 70°C. This solvent is a so-called weak solvent, and is a hydrocarbon solvent such as normal hexane (aniline point 59° C.) and cyclohexane (aniline point 30° C.).

In the present invention, a solvent is appropriately selected depending on the type of epoxy resin and urethane-modified amine compound, so that the aniline point and the like can also be appropriately selected within the range of 12 to 70°C. Although it is not limited to contain a small amount of other solvent, it is preferably 5% by mass or less of the total solvent in order to sufficiently exert the effects of the present invention.

<Epoxy resin component B>
As the epoxy resin B of the present invention, a general epoxy resin represented by a bisphenol type and a phenol novolac type can be used. Commercially available products of general-purpose type epoxy resin include trade name "Epicoat #828" (bisphenol A type liquid epoxy resin, epoxy equivalent 184 to 194, molecular weight about 380, manufactured by Yuka Shell Co., Ltd.), "Epicoat #834-90X". (Bisphenol A type solid epoxy resin, epoxy equivalent 230 to 270, molecular weight about 470, manufactured by Yuka Shell Co., Ltd.), "Epicoat #1001" (bisphenol A type solid epoxy resin, epoxy equivalent 450 to 500, molecular weight about 900, oilification Shell company), "Epicoat #1004" (bisphenol A type solid epoxy resin, epoxy equivalent 875-975, molecular weight about 1600, manufactured by Yuka Shell Co., Ltd.), "Epicoat #1007" (bisphenol A type solid epoxy resin, epoxy equivalent) 1750 to 2200, molecular weight of about 2900, manufactured by Yuka Shell Co., Ltd., "Epicoat #807" (bisphenol F type liquid epoxy resin, epoxy equivalent 160 to 175, molecular weight of about 330, manufactured by Yuka Shell Co., Ltd.), trade name "Epicoat #154. (Phenol novolac type epoxy resin, epoxy equivalent 176 to 180, molecular weight about 540, manufactured by Yuka Shell Co., Ltd.).

Commercially available products of flexible type epoxy resin include trade name "YR-450" (rubber modified epoxy resin, epoxy equivalent 400 to 500, molecular weight about 800 to 1000, manufactured by Toto Kasei Co., Ltd.), EPICLON EXA manufactured by DIC Corporation. "-835LV", "EPICLON 850S", "EPICLON N740", "EPICLON EXA-830CRP", "EPICLON EXA-830LVP", "EPICLON HP-820", "jER 828", "jER 806" manufactured by Mitsubishi Chemical Corporation. , "JER 1001", "jER 801N", "jER 807", "jER 152", "jER 604", "jER 630", "jER 871", "jER YX8000", "jER YX8034", "jER YX4000". , "Akuriset BPA-328" manufactured by Nippon Shokubai Co., Ltd., "TEPIC SP" manufactured by Nissan Kagaku Co., Ltd., EP4100 series, EP4000 series, EPU series manufactured by ADEKA Co., Ltd., Celoxide by Daicel Chemical Industries, Ltd. Series, Epolide series, EHPE series, YD series, YDF series, YDCN series, YDB series, Denacol series made by Nagase ChemteX Corporation, Epolite series made by Kyoeisha Chemical Co., Ltd. To be

The epoxy resin used in the present invention is not limited to the above epoxy resins, and other commercially available epoxy resins and the like can also be used.
The epoxy resin of the present invention preferably has an epoxy equivalent of 100 to 3000 from the viewpoint of curability and toughness of the coating film. Further, it is more preferably 150 to 1000 from the viewpoint of flexibility of the coating film.

The epoxy resin preferably has a number average molecular weight (polystyrene conversion by GPC) of 200 to 5,000, more preferably 300 to 2,000, from the viewpoint of coating film physical properties and coating workability.

The epoxy resin of the present invention is preferably contained in the solid content of the epoxy coating composition in an amount of 10 to 60% by mass, more preferably 15 to 50% by mass, from the viewpoints of corrosion resistance of the coating film, flexibility and coating interval. %.
The epoxy resin of the present invention may be used alone or in combination of two or more kinds.

<Urethane modified amine compound C>
The urethane-modified amine compound C of the present invention is represented by the following formula (1) and functions as a curing agent in the coating composition. And it is soluble in solvent A.
Here, being soluble in the solvent A means that when 100 g of the petroleum hydrocarbon solvent is added to 10 g of the urethane-modified amine compound C, a uniform state is easily obtained and no turbidity occurs.

（式中、Ｒ¹はヒドロキシル基を有するケチミンおよび／またはエナミンの前記ヒドロキシル基とイソシアネート基とを反応させ、ついで加水分解することによって形成される基に含まれる、Ｈ₂Ｎ−基と−Ｏ−Ｃ（＝Ｏ）−ＮＨ基との間に介在する基を表し、Ｒ²は分子量が５００〜１００００であるポリアルキレンエーテルポリオールが有する２つのヒドロキシル基とイソシアネート基とを反応させて得られる基に含まれる、２つの−Ｏ−Ｃ（＝Ｏ）−ＮＨ基の間に介在する基を表し、ｎは０〜１を表す。）
上記式（１）の化合物は、「ダイトクラールＵ−５３４２」（大都産業社製；アミン価１１０〜１４０）等として入手することができる。
上記ウレタン変性アミン化合物Ｃは、単独で用いてもよく、２種以上を併用してもよい。

(In the formula, R ¹ is a group formed by reacting the hydroxyl group of ketimine and/or enamine having a hydroxyl group with an isocyanate group, and then hydrolyzing the resulting H ₂ N— group and —O -C (= O) represents an intervening group between the -NH group, R ² is a group having a molecular weight obtained by reacting the two hydroxyl groups and isocyanate groups of the polyalkylene ether polyol is 500 to 10000 Which represents a group interposed between two —O—C(═O)—NH groups contained in, and n represents 0 to 1.)
The compound of the above formula (1) can be obtained as "Daitokural U-5342" (manufactured by Daito Sangyo Co., Ltd.; amine number 110 to 140) and the like.
The urethane modified amine compound C may be used alone or in combination of two or more kinds.

In the present invention, the urethane-modified amine compound C is contained in the solid content of the coating composition in an amount of 1 to 18 mass% from the viewpoints of adhesion and coating interval. It is preferably 3 to 15% by mass.

<Pigment component D>
The pigment component D contains at least one of a coloring pigment, an extender pigment and a rust preventive pigment, and particularly preferably contains a rust preventive pigment.

Examples of color pigments include titanium oxide, red iron oxide, yellow iron oxide, phthalocyanine blue, phthalocyanine green, carbon black, quinacridone red, naphthol red, benzimidazolone yellow, Hansa yellow, benzimidazolone orange and dioxazine violet. Is mentioned. Examples of extender pigments include barium sulfate, calcium carbonate, talc, clay, mica, alumina and the like.

Examples of the rust preventive pigment of the present invention include phosphoric acid rust preventive pigment, boric acid rust preventive pigment, molybdic acid rust preventive pigment, vanadic acid rust preventive pigment, and the like. Or, it is possible to use two or more kinds in combination, but it is preferable to use two kinds in combination from these, more preferably, a phosphoric acid-based anticorrosive pigment and a boric acid-based anticorrosive pigment. Good to use.

Here, examples of the phosphoric acid-based rust preventive pigments include zinc orthophosphate, calcium orthophosphate, aluminum orthophosphate, orthophosphoric acid metal salts such as magnesium orthophosphate, aluminum pyrophosphate, calcium pyrophosphate, tin pyrophosphate, pyrophosphate, iron pyrophosphate, and pyrophosphate. Titanate, metal pyrophosphate such as magnesium pyrophosphate, manganese pyrophosphate, metal tripolyphosphate such as iron tripolyphosphate, aluminum tripolyphosphate, metal metaphosphate such as aluminum metaphosphate, calcium metaphosphate, iron metaphosphate, tin metaphosphate Examples of the salt include layer compounds such as layered titanium phosphate, layered zirconium phosphate, and layered metal phosphate-based layered compounds such as tin phosphate.Examples of the boric acid-based rust preventive pigment include barium borate and metaboron. Examples thereof include barium acid, calcium metaborate, and magnesium metaborate. Examples of molybdic acid rust-preventive pigments include zinc molybdate, calcium molybdate, zinc calcium molybdate, magnesium molybdate, nickel molybdate, and molybdic acid. Examples thereof include cobalt, strontium molybdate, zinc phosphomolybdate, calcium phosphomolybdate, aluminum phosphomolybdate, and the like. Examples of vanadate-based rust-preventive pigments include vanadium pentoxide, calcium vanadate, potassium metavanadate, and metavanadine. Examples thereof include ammonium acid salt and sodium metavanadate.

In the present invention, the mixing ratio of the anticorrosion pigment is preferably 1 to 40% by mass, more preferably 5 to 30% by mass in the solid content of the coating composition from the viewpoint of the rust preventive film forming property and water resistance. %. A rust-preventive film is now formed at the interface between the galvanized steel sheet and the coating film, and it is possible to obtain a high degree of rust-preventive property and adhesion.

The compounding mass ratio of the phosphoric acid type anticorrosive pigment and the boric acid type anticorrosive pigment is 10/90 to 90/10, preferably 30/70 to 70/30. In particular, when a urethane-modified amine compound and a phosphoric acid-based rust-preventive pigment or a boric acid-based rust-preventive pigment are used in combination, the adhesion durability of the coating film is further enhanced.

Further, the mass ratio of the pigment component D and the resin component (the total of the epoxy resin B and the urethane modified amine compound C) is preferably 80/20 to 50/50 from the viewpoint of the rust preventive film forming property and the adhesive property.

<Other additives>
Further, for the coating composition of the present invention, if necessary, a pigment dispersant, a defoaming agent, a surface modifier, an ultraviolet absorber, a light stabilizer, a dryer, an anti-skinning agent, a leveling agent, etc. Additives for paints can be added.

<Use>
In the present invention, the non-ferrous metal steel sheet to be coated with the coating composition may be, for example, a galvanized steel sheet, which is preferably a structure using a galvanized steel material, for example, power transmission or communication. Examples are steel towers, bridge facilities, various plants, etc., but are not limited thereto.

The galvanized steel sheet to be coated may be coated with the coating composition of the present invention after removing the old coating film, or may be coated with the old coating film left. That is, for example, a coating film having excellent adhesion can be obtained even when it is applied to a galvanized steel sheet whose base material is adjusted to 2 to 4 types of keren.

<Application method>
The coating method of the coating composition is not particularly limited, and known coating means such as brush coating, roller coating, air spray coating and airless spray coating can be used.

The present invention will be specifically described below with reference to examples. In Examples 1 to 9 and Comparative Examples 1 to 4, the respective materials were mixed and kneaded as shown in Table 1 (parts by mass) to prepare a main agent and a curing agent. The epoxy resin and the urethane-modified amine compound were uniformly dissolved in the base resin and the curing agent, respectively. The curing agent was mixed with the main component immediately before use and subjected to various tests.

The epoxy resin, phosphate-based anticorrosive pigment, borate-based anticorrosive pigment, talc, kaolin, titanium oxide, urethane-modified amine, polyamine, and polyamidoamine shown in Table 1 are as follows.

-Epoxy resin: "EPICRON 5920-70MS", a mineral spirit solution of alkylphenol novolac type epoxy modified resin (solid content 70%), epoxy equivalent 890-970, manufactured by DIC Ltd.-Phosphate rust preventive pigment: "K -WHITE #82", condensed aluminum phosphate, manufactured by Teika Co., Ltd., borate-based rust preventive pigment: "Barium metaborate BUSAN 11-M1", barium metaborate, manufactured by Sakai Chemical Industry Co., Ltd., Talc: " Talc PK-50", hydrous magnesium silicate, manufactured by Fuji Talc Industry Co., Ltd. Kaolin: "Neogen2000", calcined kaolin, Imerys Kaolin Inc. , Titanium oxide: "TITONE R-5N", titanium oxide (IV), Sakai Chemical Industry Co., Ltd. / Urethane modified amine: "Daitokral U-6181", urethane modified alicyclic polyamine solution (solid content 90 %), amine value 110-130 manufactured by Daito Sangyo Co., Ltd./Polyamine: "Fujicure FXP8086", modified aliphatic polyamine, amine value 200-220, manufactured by T&K TOKA Co., Ltd.
-Polyamidoamine: "Tomide TXP-696", polyamidoamine, amine value 310-350, manufactured by T&K TOKA Co., Ltd.
・Petroleum hydrocarbon solvent: Solvesso 100 (manufactured by Exxon Mobil, mixed aniline point: 14° C.)
・Alcoholic solvent: isobutyl alcohol

A zinc-coated plate (zinc-plated steel plate, zinc coating amount 350 g/m ² ) specified in JIS K5600-1-4:2004 was dry-polished using abrasive paper using silicon carbide sand having a grain size of #220. The surface of the galvanized steel sheet after polishing was washed with xylene to prepare a clean state, which was used as a test plate.

The epoxy resin coating composition, in which the above curing agent was mixed with the main component immediately before, was applied to the prepared test plate with a brush so that the dry film thickness would be 60 μm, and dried in a room temperature environment for 24 hours. Then, a weak solvent type fluororesin-based top coating "V CFC #100H Smile Top Coating" (manufactured by Dainippon Paint Co., Ltd.) was applied as a top coating by a brush so that the dry film thickness was 30 μm. After 24 hours, the back surface and the periphery of the test piece were coated with the same paint so as not to affect the test, dried in the same environment for 6 days, and then subjected to various tests described below.

(1) Evaluation of adhesion durability The test piece produced by the above method was repeatedly heated and cooled at a constant temperature of -30°C for 3 hours, a temperature increase of 3 hours, a temperature of 70°C for 3 hours, and a temperature decrease of 3 hours for 12 hours. It was subjected to a test and the adhesion durability of the coating film was evaluated. The relative humidity in the environment was constantly maintained at 90% RH or higher.

The degree of deformation of the coating film appearance was evaluated for the coating film after 50 and 100 cycles from the start of the test. The criteria for judgment were set as follows.
<Criteria for coating film deformation>
◯: No change was observed in the appearance of the coating film after the test.
X: Defects such as swelling, rust, cracking, and peeling were observed on the coating film after the test.

Further, the adhesive force of the coating film was measured by an adhesion tester manufactured by Elcometer. In addition, according to JIS-K5600-5-6:1999 "Adhesiveness (cross-cut method)", a grid-like notch is made in the coating film at intervals of 2 mm, and adhesiveness is evaluated by a tape peeling test. It was Each criterion was set as follows.
<Adhesive force judgment criteria>
⊚: >7.0 MPa
◯: 2.0 to 7.0 MPa
X: <2.0 MPa
<Cross-cut adhesion (cross-cut method) criteria>
◯: Classification 0 to 1 (peeling rate of coating film after evaluation is 5% or less)
X: Classification 2 to 5 (peeling rate of coating film after evaluation exceeds 5%)

(2) Anticorrosion evaluation test For the test piece prepared by the above method, according to JIS-5600-7-9:2006, 7.5 (how to make cuts), cross-shaped cuts reaching the substrate And subjected to a cycle corrosion test (cycle D) specified in JIS-5600-7-9 "Cycle corrosion test method".

With respect to the coating films after 120 cycles, 240 cycles and 360 cycles from the start of this test, the degree of deformation of the coating film appearance was evaluated by the same criteria as the durability of the coating film. In addition, the deformation width of the coating film from the cut flaws was evaluated according to the following criteria.
<Defect width determination criteria for flaws>
◎: <2.0 mm
○: 2.0 to 3.0 mm
×: >3.0 mm

From the results shown in Table 1, the coating compositions of Examples 1 to 6 containing the urethane-modified amine compound in the curing agent and having the phosphate and borate-based rust-preventive pigments exhibited durability against adhesion to galvanized steel sheets. It can be seen that the film has excellent properties and maintains good coating film adhesion over a long period of time as compared with Comparative Examples 1 to 4.

In addition, the same coating composition exhibited high anticorrosion properties on a galvanized steel sheet, and the effect of suppressing the deterioration of the zinc plating exposed due to the cut flaws was confirmed from the evaluation results of the deformation width of the flaw portion.

Claims (6)

A two- component curing type epoxy resin coating composition for a galvanized steel sheet containing a main agent and a curing agent,
The base resin contains at least a solvent A having a mixed aniline point or an aniline point in the range of 12 to 70° C. defined by JIS K 2256, and an epoxy resin component B soluble in the solvent A. Component B contains an epoxy resin having two or more epoxy groups in the molecule,
A coating composition in which the curing agent contains a urethane-modified amine compound C soluble in the solvent A. The coating composition according to claim 1, wherein the urethane-modified amine compound C comprises a compound represented by the following structure (1).

(In the formula, R ¹ is a group formed by reacting the hydroxyl group of ketimine and/or enamine having a hydroxyl group with an isocyanate group, and then hydrolyzing the resulting H ₂ N— group and —O -C (= O) represents an intervening group between the -NH group, R ² is a group having a molecular weight obtained by reacting the two hydroxyl groups and isocyanate groups of the polyalkylene ether polyol is 500 to 10000 Which represents a group interposed between two —O—C(═O)—NH groups contained in, and n represents 0 to 1.) The pigment component D is contained in at least one of the main component or the curing agent, the pigment component D contains a rust preventive pigment, and the rust preventive pigment is a borate and a phosphate. Coating composition. The coating composition according to claim 3, wherein the mass ratio of the pigment component D and the resin component (the total of the epoxy resin B and the urethane-modified amine compound C) is 80/20 to 50/50. A coating method for a galvanized steel sheet using a two-component curing type epoxy resin coating composition containing a main agent and a curing agent,
The base resin contains at least a solvent A having a mixed aniline point or an aniline point in the range of 12 to 70° C. defined by JIS K 2256, and an epoxy resin component B soluble in the solvent A. Component B contains an epoxy resin having two or more epoxy groups in the molecule,
A coating method for a galvanized steel sheet, wherein the curing agent comprises a coating composition containing a urethane-modified amine compound C soluble in the solvent A. A coated product of a two-component curing type epoxy resin coating composition containing a main agent and a curing agent,
The object to be coated is a galvanized steel sheet, the main component is at least a mixed aniline point defined in JIS K 2256 or a solvent A having an aniline point in the range of 12 to 70° C., and an epoxy soluble in the solvent A. A resin component B, the epoxy resin component B contains an epoxy resin having two or more epoxy groups in the molecule,
A coated article, wherein the curing agent is a coating composition containing a urethane-modified amine compound C soluble in the solvent A.