JP2017082034A - Cationic electrodeposition paint composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cationic electrodeposition paint composition that can impart an excellent corrosion resistance even if various metallic materials are not previously subjected to chemical conversion treatment such as zinc phosphate treatment.SOLUTION: Provided is a cationic electrodeposition paint composition containing a resin emulsion comprising an amino group-modified epoxy resin (A) and a curative (B) capable of crosslinking the amino group-modified epoxy resin (A), and a soluble type Bi (C), and in which the amino group-modified epoxy resin (A) is obtained by reacting an epoxy resin (A1) and an amine compound (A2) and in which the epoxy resin (A1) is an epoxy resin (A1) obtained by reacting (a1) a propylene oxide addition di-epoxy resin represented by formula (1), (a2) a bisphenol compound, (a3) a di-epoxy resin, and (a4) a dicarboxylic acid in which two carboxyl groups are bonded via at least 1 carbon atom.SELECTED DRAWING: None

Description

The present invention relates to a cationic electrodeposition coating material capable of forming a film having excellent corrosion resistance on a metal material, particularly an untreated steel sheet not subjected to chemical conversion treatment or the like.

Conventionally, electrodeposition coating is generally used as a technique for imparting excellent corrosion resistance to various metal materials. However, since the desired corrosion resistance cannot be obtained only with the electrodeposition coating film obtained by electrodeposition coating, chemical conversion treatment such as zinc phosphate-based chemical conversion treatment has been generally applied before the electrodeposition coating. It was.

Zinc phosphate-based chemical conversion treatment has been put into practical use for a long time, and exhibits excellent corrosion resistance by improving coating film adhesion and suppressing corrosion under the coating film. On the other hand, insoluble iron phosphate, commonly called sludge, is formed as a by-product of the chemical conversion reaction. Usually, this sludge is precipitated in the system and periodically discharged outside the system and discarded as industrial waste. However, reduction of industrial waste is a big issue from the viewpoint of global environmental conservation, and a chemical conversion treatment liquid and a surface treatment method that do not generate waste are strongly desired.

Electrodeposition coating, on the other hand, is broadly divided into anion electrodeposition coating and cationic electrodeposition coating, but for automobile bodies, automobile parts, home appliances, building materials, etc., which are metal components mainly made of iron-based materials. Cationic electrodeposition coating is widely applied. In cationic electrodeposition coating, once rust prevention was ensured by blending a chromium compound or a lead compound. However, the specifications of chromium compounds and lead compounds that have been used in conventional cationic electrodeposition coatings are limited by environmental regulations, especially ELV regulations in Europe. Cationic electrodeposition coatings that do not use chromium compounds or lead compounds are the mainstream. It has become.

However, in recent years, certain electrodeposition paints have been proposed in which treatment is performed in a single dipping step without using a zinc phosphate-based chemical conversion treatment prior to cationic electrodeposition coating. Specifically, Patent Document 1 discloses a cationic electrodeposition coating composition containing an amino group-containing modified epoxy resin, a blocked polyisocyanate, a phenol resin, a metal compound, and nitrogen oxide ions. A method is disclosed in which a metal coating is formed by energization and an electrodeposition coating is formed by second-stage energization.

JP 2011-84723 A

When the present inventors examined the method disclosed by patent document 1, depending on the method, corrosion resistance may be considerably inferior compared with the prior art which is a combination of zinc phosphate and cationic electrodeposition coating. It has become clear. Therefore, the present invention is excellent for various metal materials even if the metal material is a metal to be treated (hereinafter also referred to as an untreated steel plate) that has not been subjected to chemical conversion treatment such as zinc phosphate treatment. It aims at providing the cationic electrodeposition coating composition which can provide corrosion resistance.

［式（１）中、Ｒ１は、置換基を有していてもよい炭素数３〜１０のアルキレン基、置換基を有していてもよいシクロへキシレン基、置換基を有していてもよいフェニレン基、又は−Ｒａ−Ｒｂ−Ｒｃ−であり、Ｒａ及びＲｃは、シクロへキシレン基又はフェニレン基であり、Ｒｂは、１又は２個の置換基を有していてもよいメチレン基であり、ｍ及びｎは、相互に独立しており、１〜２０のいずれかの整数である］で示されるプロピレンオキサイド付加ジエポキシ樹脂（ａ１）とビスフェノール化合物（ａ２）と式（１）とは異なるジエポキシ樹脂（ａ３）と２つのカルボキシル基が少なくとも１個の炭素原子を介して結合されているジカルボン酸（ａ４）とを反応させて得られる、アミノ基変性エポキシ樹脂（Ａ）；
（ii）前記ジエポキシ樹脂（ａ３）が、式（２）：

［式（２）中、Ｒ３及びＲ４は、それぞれ独立に、単結合、アルキレン基、フェニレン基、及びシクロヘキシレン基から選ばれ、Ｘ_１及びＹ_１は、それぞれ独立に水素原子及びアルキル基から選ばれる］で示される化合物である、上記（ｉ）に記載のカチオン電着塗料組成物；
（iii）前記プロピレンオキサイド付加ジエポキシ樹脂（ａ１）のＲ１が、式（３）、式（４）又は式（５）：

［式（３）、（４）及び（５）中、Ｘ_２、Ｘ_３、Ｙ_２及びＹ_３は、互いに独立に水素原子、アルキル基及びフェニル基から選ばれ、Ｘ_４及びＹ_４は、互いに独立に水素原子、アルキル基、フェニル基、アルコキシル基及びヒドロキシル基から選ばれる］で示される基であり、且つ、式（１）におけるｍ及びｎは、相互に独立しており、１〜５のいずれかの整数である、上記（ｉ）又は（ii）に記載のカチオン電着塗料組成物；
（iv）前記ジカルボン酸（ａ４）は、２つのカルボキシル基が１〜２０個のアルキレン基を介して結合される化合物であり、前記アルキレン基はアルキル基、アルケニル基、アルカジエニル基又はメチレン基を有していてもよく、また、前記アルキレン基の炭素数が２〜２０個である場合、隣り合う炭素原子を介して環を構成してもよく、前記環はアルキル基及びアルケニル基から選択される１又は２以上の置換基を有していてもよい、上記（ｉ）から（iii）のいずれかに記載のカチオン電着塗料組成物；
（ｖ）前記エポキシ樹脂（Ａ１）のエポキシ当量が１０００以上５０００以下であり、且つ、前記アミノ基変性エポキシ樹脂（Ａ）のアミン価が５以上３０以下である、上記（ｉ）から（iv）のいずれかに記載のカチオン電着塗料組成物；
（vi）前記プロピレンオキサイド付加ジエポキシ樹脂（ａ１）の量が、前記プロピレンオキサイド付加ジエポキシ樹脂（ａ１）、前記ビスフェノール化合物（ａ２）、前記ジエポキシ樹脂（ａ３）及び前記ジカルボン酸（ａ４）の総質量に対して１質量％以上５０質量％以下であり、且つ、前記ジカルボン酸（ａ４）の量が前記総質量に対して１重量％以上２０質量％以下を含む、上記（ｉ）から（ｖ）のいずれかに記載のカチオン電着塗料組成物；
（vii）前記硬化剤（Ｂ）がブロック化ポリイソシアネート型硬化剤である、上記（i）から（vi）のいずれかに記載のカチオン電着塗料組成物；
（viii）前記カチオン電着塗料組成物は、可溶型Ｂｉ（Ｃ）を、金属Ｂｉ元素として１０から１０，０００ｍｇ／Ｌ含有する、上記（i）から（vii）のいずれかに記載のカチオン電着塗料組成物；
（ix）更にＺｒ、Ｔｉ及びＨｆからなる群より選ばれる１種又は２種以上の水溶性金属化合物（Ｄ）を、金属元素として合計で１０から１０，０００ｍｇ／Ｌ含有する、上記（i）から（viii）のいずれかに記載のカチオン電着塗料組成物；
（x）前記（i）から（ix）のいずれかに記載のカチオン電着塗料組成物に被処理金属を浸漬し、無通電で３〜６００秒間浸漬することで前記被処理金属上にＢｉを主成分とする皮膜を形成させ、その後陰極電解によって前記アミノ基変性エポキシ樹脂及び前記硬化剤を主成分とする塗膜を前記被膜上に形成させる工程を含む金属表面処理方法；
（xi）前記（i）から（ix）のいずれかに記載のカチオン電着塗料組成物に、化成処理を施していない金属被塗物を浸漬し電着塗装して得られる塗装物品；
等である。 As a result of researches to solve the above problems, the inventors have reached the following invention.
That is, the present invention
(I) A cationic emulsion containing an amino group-modified epoxy resin (A) and a resin emulsion containing a curing agent (B) capable of crosslinking the amino group-modified epoxy resin (A), and soluble Bi (C). A coating composition comprising:
The amino group-modified epoxy resin (A) is obtained by reacting an epoxy resin (A1) with an amine compound (A2), and the epoxy resin (A1) is represented by the formula (1):

[In Formula (1), R1 may have a C3-C10 alkylene group which may have a substituent, a cyclohexylene group which may have a substituent, and a substituent. A good phenylene group, or -Ra-Rb-Rc-, where Ra and Rc are a cyclohexylene group or a phenylene group, and Rb is a methylene group optionally having one or two substituents. And m and n are independent of each other and are any integer of 1 to 20, and the propylene oxide-added diepoxy resin (a1), the bisphenol compound (a2), and the formula (1) are different. An amino group-modified epoxy resin (A) obtained by reacting a diepoxy resin (a3) with a dicarboxylic acid (a4) in which two carboxyl groups are bonded via at least one carbon atom;
(Ii) The diepoxy resin (a3) has the formula (2):

[In Formula (2), R 3 and R 4 are each independently selected from a single bond, an alkylene group, a phenylene group, and a cyclohexylene group, and X ₁ and Y ₁ are each independently selected from a hydrogen atom and an alkyl group. The cationic electrodeposition coating composition according to (i) above, which is a compound represented by
(Iii) R1 of the propylene oxide-added diepoxy resin (a1) is represented by formula (3), formula (4) or formula (5):

[In the formulas (3), (4) and (5), X ₂ , X ₃ , Y ₂ and Y ₃ are independently selected from a hydrogen atom, an alkyl group and a phenyl group, and X ₄ and Y ₄ are Independently selected from the group consisting of a hydrogen atom, an alkyl group, a phenyl group, an alkoxyl group and a hydroxyl group], and m and n in the formula (1) are independent of each other; The cationic electrodeposition coating composition according to (i) or (ii) above, which is an integer of any one of
(Iv) The dicarboxylic acid (a4) is a compound in which two carboxyl groups are bonded via 1 to 20 alkylene groups, and the alkylene group has an alkyl group, an alkenyl group, an alkadienyl group, or a methylene group. In addition, when the alkylene group has 2 to 20 carbon atoms, a ring may be formed through adjacent carbon atoms, and the ring is selected from an alkyl group and an alkenyl group. The cationic electrodeposition coating composition according to any one of (i) to (iii), which may have one or two or more substituents;
(V) The epoxy equivalent of the epoxy resin (A1) is 1000 or more and 5000 or less, and the amine value of the amino group-modified epoxy resin (A) is 5 or more and 30 or less. The cationic electrodeposition coating composition according to any one of
(Vi) The amount of the propylene oxide-added diepoxy resin (a1) is the total mass of the propylene oxide-added diepoxy resin (a1), the bisphenol compound (a2), the diepoxy resin (a3), and the dicarboxylic acid (a4). 1 to 50% by mass and the amount of the dicarboxylic acid (a4) includes 1 to 20% by mass with respect to the total mass. The cationic electrodeposition coating composition according to any one of the above;
(Vii) The cationic electrodeposition coating composition according to any one of (i) to (vi), wherein the curing agent (B) is a blocked polyisocyanate type curing agent;
(Viii) The cation according to any one of (i) to (vii), wherein the cationic electrodeposition coating composition contains 10 to 10,000 mg / L of soluble Bi (C) as a metal Bi element. Electrodeposition coating composition;
(Ix) The above (i), further comprising one or more water-soluble metal compounds (D) selected from the group consisting of Zr, Ti and Hf as metal elements in a total of 10 to 10,000 mg / L To (viii) of the cationic electrodeposition coating composition;
(X) Bi is deposited on the metal to be treated by immersing the metal to be treated in the cationic electrodeposition coating composition according to any one of (i) to (ix), and then immersing for 3 to 600 seconds without current. A metal surface treatment method comprising a step of forming a film mainly comprising the amino group-modified epoxy resin and the curing agent on the film by cathodic electrolysis;
(Xi) a coated article obtained by immersing a metal coating that has not been subjected to chemical conversion treatment into the cationic electrodeposition coating composition according to any one of (i) to (ix) above;
Etc.

  ADVANTAGE OF THE INVENTION According to this invention, even if this metal material is an untreated steel plate with respect to various metal materials, it becomes possible to provide the cationic electrodeposition coating composition which can provide the outstanding corrosion resistance.

  First, the amino group-modified epoxy resin (A) according to the present invention will be described. In the following, there are descriptions of groups containing a hydrocarbon moiety such as “alkyl”, “alkylene”, “alkenyl”, “alkadienyl”, “hydroxyalkyl”, “alkylene glycol”, and “alkanolamine”. In this case, unless otherwise specified, the number of carbon atoms of the group is preferably 1 to 6 independently of each other. Moreover, about each of each raw material, you may use individually and may be used in combination of 2 or more type.

<< 1. Amino group-modified epoxy resin (A) >>
The amino group-modified epoxy resin (A) is obtained by reacting the epoxy resin (A1) and the amine compound (A2). The epoxy resin (A1) is composed of a propylene oxide-added diepoxy resin (a1), a bisphenol compound (a2), a diepoxy resin (a3) different from (a1), and two carboxyl groups having at least one carbon atom. It can be obtained by reacting dicarboxylic acid (a4) bound via Hereinafter, each raw material will be described in detail.

<1-1. Raw material>
{1-1-1. Raw material / propylene oxide-added diepoxy resin (a1)}
The propylene oxide addition diepoxy resin (a1) is a resin represented by the above formula (1). In the above formula (1), R1 may have a C3-C10 alkylene group which may have a substituent, a cyclohexylene group which may have a substituent, or a substituent. It is a phenylene group or -Ra-Rb-Rc-. Ra and Rc are a cyclohexylene group or a phenylene group. Rb is a methylene group which may have 1 or 2 substituents. m and n are mutually independent and are any integers of 1-20.

  Here, as a substituent in a C3-C10 alkylene group, a cyclohexylene group, a phenylene group, and a methylene group which has a substituent, an alkyl group, a phenyl group, etc. can be mentioned, for example. Furthermore, these substituents may be substituted with another functional group (for example, an alkyl group, a phenyl group, etc.). The alkyl group may be linear, branched or cyclic. In the present specification, the “substituent” means the above-described alkyl group, phenyl group or the like unless otherwise specified.

R1 in the above formula (1) is, for example, a biscyclohexylene group represented by the above formula (3), a bisphenylene group represented by the above formula (4), or a phenylene group represented by the above formula (5). . The formula (3) in, X ₂ and Y ₂ are each independently a hydrogen atom, an alkyl group or a phenyl group. In the formula (4), X ₃ and Y ₃ are each independently a hydrogen atom, an alkyl group or a phenyl group. In the above formula (5), X ₄ and Y ₄ are each independently a hydrogen atom, an alkyl group, a phenyl group, an alkoxyl group or a hydroxyl group. The alkyl group as X ₂ , Y ₂ , X ₃ , Y ₃ , X ₄ and Y ₄ is not particularly limited as long as it is linear or branched, but an alkyl group having 1 to 6 carbon atoms. Are preferable, and an alkyl group having 1 to 3 carbon atoms is more preferable. Further, the alkoxyl group as X ₄ and Y ₄ is not particularly limited as long as it is linear or branched, but is preferably an alkoxyl group having 1 to 6 carbon atoms, and an alkoxyl having 1 to 3 carbon atoms. Groups are more preferred.

  M and n in the above formula (1) may be any integer from 1 to 20 as described above, but are preferably any integer from 1 to 5, and both m and n are from 1 It is more preferably any integer of 3, and it is particularly preferable that both m and n are 1.

  The propylene oxide addition diepoxy resin (a1) of the above formula (1) was obtained by a known method, more specifically, addition or addition polymerization of propylene oxide to a polyol compound having hydroxyl groups at both ends of R1. It can be obtained by reacting a polyether compound (having a hydroxyl group at the terminal) with epichlorohydrin and diepoxidizing.

  More specifically, as the polyol compound, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8- Linear or cyclic alkylene glycol in which hydroxyl groups are bonded to carbon atoms at both ends, such as octanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclohexanediol; catechol, resorcinol, Polyhydric phenols having two or more hydroxyl groups such as hydroquinone and pyrogallol; 2,2-bis (4-hydroxycyclohexyl) propane (hydrogenated bisphenol A), hydrogenated bisphenol F, hydrogenated bisphenol E, hydrogenated bisphenol B, Hydrogenated bisphenol AP, hydrogenated bisphenol BP, bisphenol And the like can be given; Nord A, bisphenol F, bisphenol E, bisphenol B, bisphenol AP, polyphenol compounds such as bisphenol BP or its hydride.

{1-1-2. Raw material / bisphenol compound (a2)}
The bisphenol compound (a2) is not particularly limited as long as it is a compound having two phenolic OH groups in one molecule. For example, bisphenol A, bisphenol F, bisphenol E, bisphenol B, bisphenol S, bisphenol AP And bisphenol BP. Of these, bisphenol A and bisphenol F are preferred.

{1-1-3. Raw material / diepoxy resin (a3)}
The diepoxy resin (a3) is a compound having two epoxy groups in one molecule other than the propylene oxide-added diepoxy resin (a1). The diepoxy resin (a3) generally has an epoxy equivalent within the range of 170 to 500, preferably 170 to 400. The diepoxy resin (a3) is preferably a compound represented by the above formula (2). In the above formula (2), R3 and R4 may be the same or different, and examples thereof include a single bond, an alkylene group, a phenylene group, and a cyclohexylene group. X ₁ and Y ₁ are each independently a hydrogen atom or an alkyl group. The alkyl group as X ₁ and Y ₁ is not particularly limited as long as it is linear or branched, but is preferably an alkyl group having 1 to 6 carbon atoms, and an alkyl group having 1 to 3 carbon atoms. More preferred.

  The diepoxy resin (a3) includes, for example, the polyol compound, or two hydroxyl groups on the same carbon atom; one hydroxyl group and one hydroxyalkyl group, phenol group, or cyclohexanol group; and one hydroxyalkyl group. 1 phenol group or cyclohexanol group; 1 phenol group and 1 cyclohexanol group; or 2 hydroxyalkyl groups (which may be the same or different); It can be obtained by the reaction of the above alkylene glycol with epihalohydrin (for example, epichlorohydrin). Examples of the alkylene glycol include alkylene glycol in which two hydroxyl groups are bonded to the same carbon atom, such as 1,1-dihydroxyethane, 1,1-dihydroxypropane, and 2,2-dihydroxypropane; 2-hydroxypropanol Alkylene glycols having one hydroxyl group and one hydroxyalkyl group bonded to the same carbon atom, such as 2-hydroxybutanol; 2,2- (dihydroxymethyl) ethane, 2,2- (dihydroxyethyl) propane, 2 , 2-dimethyl-1,3-propanediol, 2,2-dimethyl-1,4-butanediol, 3,3-diethyl-1,6-hexanediol, etc., one or two on the same carbon atom An alkylene glycol having a hydroxyalkyl group bonded thereto; 4- (1-hydroxyethyl) Alkylene glycol in which one hydroxyl group and one phenol group are bonded to the same carbon atom, such as phenol, 3- (1-hydroxyethyl) phenol, 4- (1-hydroxypropyl) phenol; 4- (1-hydroxy Alkylene glycols in which one hydroxyl group and one cyclohexanol group are bonded to the same carbon atom, such as ethyl) cyclohexanol, 2- (1-hydroxyethyl) cyclohexanol; 4-hydroxyphenyl-2-propanol, 4- Alkylene glycol in which one hydroxyalkyl group and one phenol group are bonded to the same carbon atom, such as hydroxyphenyl-2-butanol; 2- (4-hydroxycyclohexyl) -1-propanol, 2,2-dimethyl- 2- (4-Hydroxycyclohexyl)- An alkylene glycol in which one hydroxyalkyl group and one cyclohexanol group are bonded to the same carbon atom, such as ethanol; 2- (4-hydroxyphenyl) -2- (4-hydroxycyclohexyl) propane, 1- ( An alkylene glycol in which one phenol group and one cyclohexanol group are bonded to the same carbon atom, such as 4-hydroxyphenyl) -1- (4-hydroxycyclohexyl) propane;

  In the production of the diepoxy resin (a3), in addition to the polyol compound and the various alkylene glycols, for example, 4,4′-dihydroxybenzophenone, bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy) -2-tert-butylphenyl) -2,2-propane, bis (4-hydroxy-3-tert-butylphenyl) -2,2-propane, bis (2-hydroxynaphthyl) methane, tetrakis (4-hydroxyphenyl) ) -1,1,2,2-ethane, 4,4′-dihydroxydiphenylsulfone, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, bis (4-hydroxyphenyl) -2,2-dichloroethylene, Use 2,2-bis (3-methyl-4hydroxyphenyl) propane, etc. Rukoto can.

  The diepoxy resin (a3) obtained from these raw materials may be used alone or in combination of two or more in the production of the amino group-modified epoxy resin (A). When the amino group-modified epoxy resin (A) is produced using two or more kinds of diepoxy resins (a3), they may be added separately or simultaneously.

{1-1-4. Raw material / dicarboxylic acid (a4)}
The dicarboxylic acid (a4) is a compound in which two carboxyl groups are bonded via at least one carbon atom. A suitable dicarboxylic acid is a compound in which two carboxyl groups are bonded via a linear alkylene group (R2) having 1 to 20 carbon atoms, as shown by the following formula (6). In addition, the alkylene group (R2) in the compound of the following formula (6) is one or more substituents selected from an alkyl group, an alkenyl group, an alkadienyl group and a methylene group, or an alkyl group and an alkenyl group. Each may have one or two or more substituents selected from an alkadienyl group and a methylene group. In addition, when the alkylene group (R2) in the compound of the following formula (6) has 2 to 20 carbon atoms, a ring may be formed through adjacent carbon atoms of the alkylene group. The ring may have one or more substituents selected from an alkyl group and an alkenyl group, and preferably has two substituents of an alkyl group and / or an alkenyl group. . When the ring has two substituents, the two substituents may be the same or different. Examples of the ring include a bicyclo ring in which two carbon-carbon bonds are double bonds in a cyclohexane ring, a cyclohexene ring, a benzene ring, and a decalin ring (for example, bicyclo [4.4.0] decane-1,7-diene). Etc.). The alkyl group, alkenyl group or alkadienyl group that the alkylene group (R2) may have, or the alkyl group or alkenyl group that the ring may have may be either linear or branched There may be.

  A more preferred dicarboxylic acid (a4) is a compound having a cyclic and / or unsaturated bond. Particularly preferred dicarboxylic acid (a4) is the compound of the above formula (6) having 2 to 18 carbon atoms in the alkylene group (R2); and the alkylene group (R2) has one methylene group. 1 or 2 alkyl groups having 5 to 9 carbon atoms, or 2 substituents of 1 or 2 types selected from alkyl groups, alkenyl groups and alkadienyl groups having 5 to 9 carbon atoms, Or any one of the above rings through an adjacent carbon atom of the alkylene group (R2), each ring being independently an alkyl group or alkenyl having 5 to 9 carbon atoms. It may have two substituents which are groups or alkadienyl groups; a compound.

Dicarboxylic acid (a4) is, for example, malonic acid, succinic acid, glutaric acid, 2,2-dimethylglutaric acid, 3,3-dimethylglutaric acid, adipic acid, 2,2-dimethyladipic acid, pimelic acid, suberic acid , Azelaic acid, 2-ethyl azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tri Decanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,15-pentadecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,17-heptadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, 1,19-nona Decanedicarboxylic acid, 1,20-icosanedicarboxylic acid, itaconic acid, phthalic acid, dimer Acid, 1,2-cyclohexanedicarboxylic acid, and 1,2-cyclohexene dicarboxylic acid. The dimer acid that can be used as a raw material for the epoxy resin (A1) in the present invention is, for example, commercially available Haridimer 200, 250, or 270S (each Harima Chemical Group Co., Ltd.); Tsunodim 205, 216, 228, 395 or 346 (each Chikuno Food Industry Co., Ltd.); Undyme 14, 14R, T-17, 18, T-18, 22, T-22, 27, 35, M-9, M-15, M-35 or 40, Or Century D-75, D-77, D-78 or D-1156, or Sylvatal 7001 or 7002 (each Arizona Chemical Company); Empol 1016, 1003, 1026, 1028, 1061, 1062, 1008 or 1012 (each BASF Company) ); Hydrogenated dimer acid (average M _n ˜570) Sigma-Aldrich).

{1-1-5. Raw material / amine compound (A2)}
The amine compound (A2) used in the present invention is a raw material for introducing an amino group into the epoxy resin (A1). Accordingly, the amine compound (A2) contains at least one active hydrogen capable of reacting with an epoxy group. The amine compound (A2) is not particularly limited as long as an amino group can be introduced. For example, monomethylamine, dimethylamine, monoethylamine, diethylamine, monoisopropylamine, diisopropylamine, monobutylamine, dibutylamine , Monoethanolamine, diethanolamine, mono (2-hydroxypropyl) amine, di (2-hydroxypropyl) amine, monomethylaminoethanol, monoethylaminoethanol, ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, tetraethylenepentamine , Pentaethylenehexamine, diethylaminopropylamine, diethylenetriamine, and the like, among which alkanolamine is preferred. As the primary amine, a ketimine-modified one can also be used. In addition, these amine compounds may be used independently and may be used in combination of 2 or more type. When the amino group-modified epoxy resin (A) is produced using two or more kinds of amine compounds (A2), each may be added separately or simultaneously.

<1-2. Production method of epoxy resin (A1)>
Next, the manufacturing method of an epoxy resin (A1) is explained in full detail. The epoxy resin (A1) is reacted, for example, by stirring a mixture of raw materials of propylene oxide-added diepoxy resin (a1), bisphenol compound (a2), diepoxy resin (a3) and dicarboxylic acid (a4) at a predetermined temperature. Can be manufactured. In order to promote the reaction, it is preferable to further add a reaction catalyst to the above mixture.

  The reaction catalyst is not particularly limited as long as it accelerates the reaction. For example, tertiary amines such as dimethylbenzylamine, triethylamine, tributylamine, tetraethylammonium bromide, tetrabutylammonium bromide, etc. Such quaternary ammonium salts can be used. The synthesis temperature is preferably controlled at 70 ° C. or higher and 200 ° C. or lower in consideration of the progress of the reaction.

  The epoxy equivalent of the epoxy resin obtained by the above production method is preferably, for example, 1000 or more and 5000 or less, more preferably 1250 or more and 4000 or less, and particularly preferably 1500 or more and 3000 or less. The epoxy resin (A1) within this range can be used as a raw material for a cationic electrodeposition coating composition that can realize better liquid stability and can efficiently form a predetermined film thickness. It becomes possible to produce the epoxy resin (A). The epoxy equivalent can be measured according to the potentiometric titration method of JIS K7236. The measurement can be performed using a commercially available potentiometric titrator (for example, AT-610 manufactured by Kyoto Electronics Industry).

  In the production of the epoxy resin (A1), the blending ratio of the propylene oxide-added diepoxy resin (a1), the bisphenol compound (a2), the diepoxy resin (a3) and the dicarboxylic acid (a4) is the ratio of each raw material (a1) to (a4). The total mass is as follows. The propylene oxide addition diepoxy resin (a1) is desirably 1 to 50% by mass, desirably 5 to 45% by mass, and most desirably 10 to 40% by mass. As for dicarboxylic acid (a4), 1-20 mass% is the most desirable, 5-20 mass% is more desirable, and 10-20 mass% is the most desirable. The remaining blending ratio depends on the bisphenol compound (a2) and the diepoxy resin (a3), but the bisphenol compound (a2) and the diepoxy resin (a3) are desirably 1% by mass or more. When these are within the above range, an amino group-modified epoxy resin (A) useful as a raw material of a cationic electrodeposition coating composition capable of forming a coating film having good electrodeposition-around properties, appearance, corrosion resistance, and corrosion resistance. ) Can be manufactured.

  The above reaction may be performed in a solvent by appropriately adding each raw material to the solvent. The solvent is not particularly limited as long as it is usually used in the production of resins. For example, hydrocarbon solvents such as toluene, xylene and hexane; ester solvents such as methyl acetate and ethyl acetate; Ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; Amide solvents such as dimethylformamide and dimethylacetamide; Alcohol solvents such as methanol, ethanol and isopropanol; Ether alcohols such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether Solvent; and the like. These may be used alone or in admixture of two or more.

<1-3. Method for producing amino group-modified epoxy resin (A)>
Next, the manufacturing method of an epoxy resin (A1) is explained in full detail. As described above, the amino group-modified epoxy resin (A) can be obtained by reacting the epoxy resin (A1) and the amine compound (A2). The reaction temperature and time are preferably, for example, 1 to 5 hours within a range of 70 ° C. or higher and 110 ° C. or lower. In the production of the amino group-modified epoxy resin (A), the compounding amount of the amine compound (A2) is adjusted so that the amine value of the amino group-modified epoxy resin (A) is in the range of 5 mgKOH / g to 30 mgKOH / g. It is preferable. Therefore, the amine value of the resulting amino group-modified epoxy resin (A) is preferably in the range of 5 mgKOH / g to 30 mgKOH / g, and more preferably in the range of 5 mgKOH / g to 20 mgKOH / g. A range of 10 mgKOH / g or more and 20 mgKOH / g or less is particularly preferable. When the amine value is within the above range, a cationic electrodeposition coating composition capable of realizing superior liquid stability, and capable of realizing sufficient throwing power and prevention of deterioration of appearance even with lower electrical conductivity is prepared. It becomes possible. The amine value, that is, the total amine value of the amino group-modified epoxy resin (A) can be measured according to the potentiometric titration method of JIS K7237.

  In addition, when an unreacted epoxy group exists even if it adjusts an amine value, you may make it react with the said unreacted epoxy group using the compound which can react with an epoxy group. The compound to be reacted with the unreacted epoxy group is not particularly limited, and examples thereof include phenol compounds, carboxylic acids, xylene formaldehyde resin and ε-caprolactone.

  The reaction between the epoxy resin (A1) and the amine compound (A2) may be the same as the solvent used when the epoxy resin (A1) is produced, but is not limited thereto. Other solvents may be used.

≪2. Cationic electrodeposition coating composition >>
The cationic electrodeposition coating composition according to the present invention includes a resin emulsion, soluble Bi (C), and optionally a water-soluble metal compound (D). Here, the resin emulsion includes an amino group-modified epoxy resin (A) and a curing agent (B) capable of crosslinking the amino group-modified epoxy resin (A). First, each component of the resin emulsion will be described in detail.

<2-1. Resin emulsion>
{2-1-1. Raw material / Amino group-modified epoxy resin (A)}
Since the details of the amino group-modified epoxy resin (A) used for the production of the resin emulsion have been described above, they are omitted here.
{2-1-2. Raw material / curing agent (B)}
The curing agent (B) is not particularly limited as long as it can crosslink the amino group-modified epoxy resin (A), and examples thereof include a blocked isocyanate compound, an amine compound, and melamine. Of these, a blocked polyisocyanate compound is preferred.

  The blocked polyisocyanate compound is an addition reaction product of a polyisocyanate compound and a blocking agent, and preferably an addition reaction product of a polyisocyanate compound and a blocking agent in an approximately stoichiometric amount. Examples of the polyisocyanate compound include tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,4′-diisocyanate, diphenylmethane-4,4′-diisocyanate, polymeric MDI (crude MDI), and bis (isocyanate methyl) cyclohexane. , Tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, isophorone diisocyanate and the like. These can be used alone or in combination of two or more.

  Moreover, a blocking agent adds to the isocyanate group of a polyisocyanate compound, and blocks that other compounds react. Thus, the blocked polyisocyanate compound produced | generated by blocking an isocyanate group with a blocking agent is stable at normal temperature. As the blocked polyisocyanate compound, it is desirable that the blocked blocking agent can be dissociated when a coating film formed from the cationic electrodeposition coating composition of the present invention is baked. In addition, the said baking temperature is about 100-200 degreeC normally.

  Examples of the blocking agent that satisfies such requirements include lactam compounds such as ε-caprolactam and γ-butyrolactam; oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenols such as phenol, para-t-butylphenol, and cresol. Compounds; alcohols such as n-butanol and 2-ethylhexanol; ether alcohol compounds such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether; and the like. These blocking agents can be used alone or in combination of two or more. In order to efficiently perform the addition and dissociation reaction of the blocking agent, and to obtain the intended addition reaction product efficiently, in advance, the hydroxyl group in the modified epoxy resin is reacted with the isocyanate group in the polyisocyanate compound, In addition, some or all of the other isocyanate groups in the polyisocyanate compound may be blocked with a blocking agent.

  Further, in order to perform the addition and dissociation reaction of the blocking agent more efficiently, it is possible to appropriately include a curing catalyst. A commercially available catalyst can be used as appropriate.

<2-2. Soluble Bi (C)>
The cationic electrodeposition coating composition of the present invention contains soluble Bi (C). Here, “soluble Bi” in the claims and in the present specification means a solvent such as a bismuth ion (usually understood as trivalent), a complex of a bismuth ion and another ligand, or the like. Refers to bismuth in a dissolved state. The source of soluble Bi (C) is specifically bismuth nitrate, bismuth phosphate, bismuth sulfate, bismuth chloride, bismuth fluoride, bismuth bromide, bismuth iodide, bismuth acetate, bismuth formate, citric acid Bismuth, bismuth lactate, bismuth oxalate, bismuth malate, bismuth tartrate, bismuth ascorbate, EDTA bismuth, NTA bismuth, HEDTA bismuth, bismuth methanesulfonate, bismuth benzenesulfonate, bismuth gluconate, bismuth heptogluconate, etc. .

  The source of soluble Bi (C) includes a soluble compound and a hardly soluble compound. In the case of a soluble compound, it is dissolved in pure water or industrial water. In the case of a poorly soluble compound, it is used by dissolving it with an inorganic acid such as nitric acid, sulfuric acid or hydrochloric acid, or an organic acid (chelating agent) such as aminocarboxylic acid, hydroxycarboxylic acid, organic sulfonic acid or organic phosphonic acid.

  The content of soluble Bi (C) (metal Bi content) is not particularly limited, but is preferably 10 to 10,000 mg / L, more preferably 25 to 8,000 mg / L, and further Preferably it is 50-8,000 mg / L. When soluble type Bi (C) exists in the said range, corrosion resistance will become favorable. When the content of soluble Bi (C) is small, the corrosion resistance is not sufficiently ensured, and when the content is large, there is a possibility that the precipitation of the resin due to energization is hindered.

<2-3. Water-soluble metal compound (D)>
The cationic electrodeposition paint of the present invention may contain one or more water-soluble metal compounds (D) selected from the group consisting of Zr, Ti and Hf. Here, it is preferable to contain a total of 10 to 10,000 mg / L of one or more water-soluble metal compounds (D) selected from the group consisting of Zr, Ti and Hf as metal elements. The term “water-soluble metal compound” in the claims and the present specification means a metal compound that dissolves in water at 20 ° C. in an amount of 1% by weight or more.

  When Zr is used as the water-soluble metal compound (D), specific examples include zirconium nitrate, zirconium oxynitrate, zirconium sulfate, zirconium oxysulfate, zirconium lactate, zirconium acetate, fluorozirconic acid, and fluorozirconium complex salt. It is done.

  When Ti is used as the water-soluble metal compound (D), specific examples include titanium sulfate, titanium oxysulfate, titanium nitrate, titanium oxynitrate, fluorotitanic acid, and fluorotitanium complex.

  When Hf is used as the water-soluble metal compound (F), specific examples include hafnium nitrate, hafnium oxide, hafnium silicate, hafnium chloride, fluorohafnium, and fluorohafnium complex salts.

<2-4. Other raw materials contained in cationic electrodeposition coating composition>
The cationic electrodeposition coating composition of the present invention is not particularly limited as long as it contains the above-described resin emulsion and soluble Bi (C), and may contain other raw materials. Other raw materials include, for example, liquid media (preferably water), pigment pastes (including pigments and resins for dispersing the pigments), organic solvents, surfactants, antifoaming agents, neutralizing acids Examples thereof include additives used in cationic electrodeposition coatings.

<2-5. Manufacturing method of resin emulsion>
The resin emulsion can be prepared, for example, by adding a neutralizing acid to a mixture of the amino group-modified epoxy resin (A) and the curing agent (B), stirring and mixing, and then diluting with water. The neutralizing acid is not particularly limited as long as it can cationize the amino group in the amino group-modified epoxy resin (A). For example, formic acid, acetic acid, lactic acid, sulfamic acid, methanesulfonic acid An organic carboxylic acid such as can be used. Of these, it is desirable to use a strong acid such as methanesulfonic acid that can produce a more stable low amine resin emulsion. These acids can be used alone or in combination of two or more. When using 2 or more types of acids, they may be added separately or simultaneously. The cationization may be performed on all amino groups or a part of amino groups.

  The amount of acid used for cationization is not particularly limited. However, when the amount is small, cations imparting water dispersibility may be reduced and the emulsion may not be formed. The degree of electrical conductivity of the cationic electrodeposition coating composition is changed from 1000 μS / cm to 2000 μS / cm, because the appearance of the coating film formed by the cationic electrodeposition coating composition containing the emulsion may be deteriorated. Thus, it is preferable to appropriately adjust the amount of acid.

<2-6. Method for producing cationic electrodeposition coating composition>
The cationic electrodeposition coating composition according to the present invention contains soluble Bi in the resin emulsion, and, if necessary, the above-mentioned water-soluble metal compound (D), liquid medium, pigment paste, organic solvent, surfactant, It can be produced by stirring and mixing a foaming agent and the like. The cationic electrodeposition coating composition may have a high concentration before dilution, or a low concentration adjusted to a desired concentration by appropriately diluting a high concentration with deionized water or the like. Good.

<2-7. Liquidity of cationic electrodeposition coating composition>
{2-7-1. PH of cationic electrodeposition coating composition}
The pH of the cationic electrodeposition coating composition according to the present invention is not particularly limited, but is preferably in the range of 2.0 or more and 7.0 or less, and in the range of 3.0 or more and 6.5 or less. More preferably, it is within. By using within this range, even if the chemical conversion treatment with the chemical conversion treatment solution is performed before the cationic electrodeposition coating with the cationic electrodeposition coating composition, there is an adverse effect due to contamination of the chemical conversion treatment solution and the metal etched by the chemical conversion treatment. Can be prevented. The substance that can be used for pH adjustment is not particularly limited, and can be performed using a known acid or base. For example, formic acid, acetic acid, lactic acid, nitric acid, sulfamic acid, methanesulfonic acid, benzenesulfonic acid, etc. And bases such as aqueous ammonia, monoethanolamine, diethanolamine, and triethanolamine can be used as appropriate. In addition, the pH value in this specification shows the value measured at 25 degreeC using the commercially available pH meter.

{2-7-2. Electrical conductivity of cationic electrodeposition coating composition}
The electrical conductivity at 25 ° C. of the cationic electrodeposition coating composition is preferably 1000 μS / cm to 2000 μS / cm. The electrical conductivity can be measured using a commercially available electrical conductivity meter (for example, Toa DKK multi-water quality meter MM-60R).

≪3. Cationic electrodeposition coating >>
{3-1. Cationic electrodeposition coating method}
In the treatment method of the present invention (first step), a metal to be treated is immersed in the metal surface treatment agent of the present invention to form a film mainly composed of a Bi film on the metal substrate to be treated (second process). Thereafter, a resin film mainly containing the amine-modified epoxy resin (A) and the curing agent (B) is formed on the Bi film by cathodic electrolysis. Each will be described in detail below.

{3-1-1. Processing method of the first step}
The first step is a step of immersing the metal to be treated in the cationic electrodeposition coating composition according to the present invention to form a film containing Bi as a main component by non-energization, that is, a chemical conversion reaction. Bi is a noble metal rather than steel, galvanized steel sheet, and aluminum alloy, which are general automobile materials, and a Bi film is deposited on these metals by an oxidation-reduction reaction. The immersion time is preferably 3 to 600 seconds.

{3-1-2. Processing method of the second step}
The second step can be carried out by applying an electric current under the condition of 50 to 400 V, preferably 100 to 300 V, with the object to be coated as a cathode. The coating bath containing the cationic electrodeposition coating composition at the time of cationic electrodeposition coating is usually in the range of 10 ° C to 50 ° C, preferably in the range of 15 ° C to 40 ° C, but is limited to these temperatures. It is not something. In addition, after a cationic electrodeposition coating, in order to harden the formed coating film, a drying process is implemented. The coating film is preferably dried, for example, within a temperature range of about 100 ° C. to about 200 ° C., and more preferably within a temperature range of about 140 ° C. to about 180 ° C. Thus, the article coated with the cationic electrodeposition coating composition of the present invention can be obtained by drying and curing the coating film. In addition, you may provide a water-washing process as needed between a cationic electrodeposition coating process and a drying process. The water washing step can be performed using, for example, ultrafiltrate, reverse osmosis permeated water, industrial water, pure water or the like.

  Although there is no restriction | limiting in particular in the thickness of the coating film formed by the said cation electrodeposition coating method, 5 micrometers or more and 50 micrometers or less are preferable, and 10 micrometers or more and 40 micrometers or less are more preferable. By being in this range, excellent corrosion resistance can be obtained. The coating thickness can be measured by an electromagnetic induction film thickness meter if the base metal is a magnetic metal, or by an overcurrent film thickness meter if the base metal is a nonmagnetic metal.

{3-2. Cationic electrodeposition coating object}
The cationic electrodeposition coating composition according to the present invention is not particularly limited as long as it can be electrodeposited. For example, cold-rolled steel materials, zinc-based plated steel materials (for example, alloyed hot-dip galvanized steel materials, hot-dip zinc) It can be applied to metal materials such as plated steel materials, electrogalvanized steel materials), aluminum steel materials, aluminum materials, and magnesium materials. These metal materials may be those subjected to surface cleaning treatment by alkali degreasing or the like, if necessary. The cationic electrodeposition coating method using the cationic electrodeposition coating composition is particularly useful for a zinc-based plated steel sheet in which pinholes are particularly likely to occur. In addition, these metal materials may be processed so as to be applicable to, for example, automobile bodies, automobile parts, household equipment, and the like.

  Hereinafter, the present invention will be described in more detail with reference to Production Examples, Examples, and Comparative Examples, but the present invention is not limited thereto. In addition, the to-be-processed raw material, degreasing agent, and coating material which were used in the Examples were arbitrarily selected from commercially available materials, and the surface treatment composition, the surface treatment solution, and the surface of the present invention The actual use of the processing method is not limited. Unless otherwise specified,% and part mean mass% and part by mass, respectively. The raw materials used for the blending are shown in Tables 1 to 4 below.

≪Production of modified epoxy resin (A1) ≫
<Production example 1>
Propylene oxide-added diepoxy resin a1-1: 100.02 g, bisphenol compound a2-1: 161.46 g, diepoxy resin a3-1: A separable flask having an internal volume of 2 liters equipped with a thermometer, a reflux condenser, and a stirrer. 638.5 g, dicarboxylic acid a4-1: 100.02 g and dimethylbenzylamine 0.75 g were added, reacted at 130 ° C. until the epoxy equivalent reached 2000, and 440.08 g of butyl cellosolve was added to stop the reaction. Resin No. 1 was obtained.

  Based on the compositions shown in Tables 5 to 8, modified epoxy No. 1 was prepared in the same manner as in Production Example 1 except that the epoxy equivalents shown in the same table were used. 2 to No. 51 was produced.

≪Production of amino group-modified epoxy resin (A) ≫
<Production Example 52>
A modified epoxy resin No. 2 was added to a 2 liter separable flask equipped with a thermometer, a reflux condenser, and a stirrer. 1: 1000.0 g, diethanolamine: 20.11 g were added and reacted at 90 ° C. for 4 hours to react with amino group-modified epoxy resin No. 1 was obtained. The amine value of this resin was 15.0 mgKOH / g.

<Production Examples 53 to 110>
In the same manner as in Production Example 52, based on the compositions shown in Tables 9 to 12, amino group-modified epoxy resin No. 2 to No. 59 was obtained. The amine value in each production example is as shown in the same table.

≪Production of blocked polyisocyanate type curing agent (B) ≫
In a reaction vessel, Cosmonate M-200 (trade name, Crude MDI manufactured by Mitsui Chemicals): 678.4 g and methyl isobutyl ketone: 115.6 g were added and the temperature was raised to 70 ° C., and then 706.0 g of butyl cellosolve was slowly added dropwise. After completion of the dropwise addition, the temperature was raised to 90 ° C. A blocked polyisocyanate type curing agent was obtained by reacting at 90 ° C. for 12 hours. When infrared absorption spectrum measurement was performed, absorption derived from unreacted isocyanate groups was not observed, and it was confirmed that the isocyanate was completely blocked.

≪Manufacture of resin emulsion≫
<Production Example 111 Emulsion No. Example 1>
Amino group-modified epoxy resin No. obtained in Production Example 52 650.0 g of 1 and 200.0 g of blocked polyisocyanate compound were mixed, and 10.0 g of methanesulfonic acid was mixed and stirred uniformly. Then, 1094.0 g of deionized water was stirred for about 10 minutes while stirring vigorously. Emulsion No. 33 with a solid content of 33%. 1 was obtained.

<Production Examples 112-169 Emulsion No. 2 to No. 59 Production Examples>
In the same manner as in Production Example 106, based on the compositions shown in Tables 13 to 16, emulsion No. 2 to No. 59 was obtained.

≪Manufacture of 30% quaternary chlorinated epoxy resin≫
In a 2 liter separable flask equipped with a thermometer, a reflux condenser, and a stirrer, 134.9 g of jER # 828 (trade name, manufactured by Japan Epoxy Resin, epoxy equivalent 180), 80.94 g of bisphenol A, 0.1 g of dimethylbenzylamine was added, and the reaction was performed at 130 ° C. until the epoxy equivalent reached 1000. After completion of the reaction, 71.7 g of butyl cellosolve was added, 13.16 g of dimethylaminoethanol and 14.79 g of 90% lactic acid were added, and the reaction was carried out at 90 ° C. for 1 hour. After the reaction, 613.36 g of deionized water was added dropwise over about 1 hour with vigorous stirring to produce a quaternary chlorinated epoxy resin having a solid content of 30%.

≪Manufacture of pigment paste≫
To 16.6 g of 30% quaternary chloride epoxy resin, 7.0 g of purified clay, 0.3 g of carbon black, 3.0 g of white coloring pigment, 1.0 g of dioctyltin dioxide and deionized water were added to a ball mill. For 20 hours to obtain a pigment paste having a solid content of 50%.

≪Manufacture of Bi additive≫
55.7 g of bismuth oxide, 133.0 g of HEDTA, and 811.3 g of deionized water were mixed and stirred until bismuth oxide was dissolved to obtain a 5% Bi aqueous solution.

≪Processing liquid preparation≫
The produced emulsion was blended in such an amount that the solid content was 16.0% and the pigment paste was 4.0% solid content. Each concentration was diluted with deionized water. Subsequently, the Bi additive and the water-soluble metal compound (D) were appropriately blended so as to obtain a predetermined metal concentration. Here, hexafluorozirconic acid and hexafluorotitanic acid were used as the water-soluble metal compound (D).

≪Preparation of test plate≫
Cold rolled steel plate: SPCC (JIS 3141) 70 × 150 × 0.8 mm (hereinafter abbreviated as SPC) is used as a test plate, and the surface is used in advance using an alkaline degreasing agent “FC-E2001” manufactured by Nihon Parkerizing Co., Ltd. Degreased by spraying for 2 seconds.
After degreasing treatment, SPC which was washed with spray water for 30 seconds was immersed in a metal surface treatment agent according to Examples and Comparative Examples prepared separately for 120 seconds as a first step, followed by 200 V × 180 seconds (of which the first 30 seconds) Was boosted to 200 V at a pressure increase rate of 7 V / second), washed with deionized water, and baked at 180 ° C. for 20 minutes to obtain a test piece having a coating thickness of 15 μm.

≪Various evaluation tests≫
In each evaluation, a score of ○ or higher is acceptable.

<Testing method and evaluation method for electrodeability with electrodeposition>
In accordance with a method for testing the ability to rotate with electrodeposition using a four-sheet box (see, for example, paragraphs 0085 to 0090 of JP 2010-90409 A), a method for testing the ability to rotate with coating was performed. In the implementation, a 70 × 150 × 0.5 mm stainless steel plate (SUS304) having one surface (the opposite surface opposite to the surface facing the four boxes) sealed with an insulating tape was used as the counter electrode. Further, the liquid level of the treatment liquid was adjusted to a position where the test piece and the counter electrode were immersed 90 mm. The temperature of the treatment liquid was maintained at 30 ° C., and the treatment liquid was stirred with a stirrer.

  In such a state, a coating film was electrolytically deposited on the surface of a test piece of four boxes by a cathodic electrolysis method using the counter electrode as an anode. Specific electrolysis conditions were cathodic electrolysis using a rectifier at a predetermined voltage for 180 seconds. The voltage was adjusted so that the coating thickness on the surface facing the counter electrode of the test piece closest to the counter electrode of the 4-box was 15 μm. Subsequently, each test piece was washed with water and then baked at 180 ° C. for 26 minutes to form a coating film.

  And the film thickness of the coating film formed on the counter electrode side of the test plate farthest from the counter electrode is measured with an electromagnetic film thickness meter (when the test piece is SPC or GA) or an eddy current film thickness meter (the test piece is AL ). The thickness of the coating film formed on the counter electrode side of the test piece furthest away from the counter electrode was obtained by measuring the film thickness at 10 randomly selected locations and calculating the average value. Then, calculate the ratio of the coating thickness formed on the counter electrode side of the test piece furthest away from the counter electrode to the coating thickness formed on the counter phase side of the test piece closest to the counter electrode, and Based on this, the recyclability with electrodeposition was evaluated.

◎: 65% or more ○: 50% or more and less than 65% △: 20% or more and less than 50% ×: less than 20%

<Gas pinhole resistance of galvannealed steel sheet>
Using the method described in << Preparation of test plate >>, an alloyed hot-dip galvanized steel sheet is used in place of a cold-rolled steel sheet, and water washing after chemical conversion treatment is performed, and it is immersed as a cathode of an electrodeposition paint bath (30 ° C.) to 200V. The film thickness was 15 μm. After the obtained coating film was baked and cured at 180 ° C. for 20 minutes, the number of pinholes therein was counted and evaluated according to the following criteria.

◎: No pinholes are generated. ○: One pinhole is generated, but there is no problem as long as it can be covered with an intermediate coating film. △: Two to nine pinholes are generated. ×: Ten or more pinholes are generated.

<Surface roughness of electrodeposition coating film>
The electrodeposition coating film having a dry coating thickness of 15 μm was measured for the centerline surface roughness (Ra) by using Surfcom 570A of Tokyo Seimitsu according to JIS B 0601 and evaluated according to the following criteria. The cut-off value λc was 0.8 mm and λs was 2.5 μm.

◎: Ra value is less than 0.20 ○: Ra value is 0.20 or more and less than 0.50 Δ: Ra value is 0.50 or more and less than 0.70 x: Ra value is 0.70 or more

<Anticorrosion>
Salt spray test (SST)
Cut the cut film with a cutter knife so as to reach the base of the cationic electrodeposition film test plate with a dry film thickness of 15 μm, and perform a 35 ° C. salt spray test for 840 hours according to JIS Z-2371. Evaluation was made according to the following criteria based on rust and swelling width from the part.

A: Maximum width of rust and swelling is 2.0 mm or less from cut (one side)
○: The maximum width of rust and swelling exceeds 2.0 mm from the cut part, and 3.0 mm or less (one side)
Δ: The maximum width of rust and swelling exceeds 3.0 mm from the cut part and is 3.5 mm or less (one side)
X: The maximum width of rust and swelling exceeds 3.5 mm from the cut part (one side)

Combined corrosion cycle test (CCT)
A cross-cut was applied to the surface-treated test plate, and a combined cycle test was performed 100 cycles in accordance with JASO-M609-91. After completion of the test, the one-side maximum swollen width (or rust width) from the crosscut portion was measured and evaluated according to the following criteria.

A: Maximum width of rust and swelling is 2.0 mm or less from cut (one side)
○: The maximum width of rust and swelling exceeds 2.0 mm from the cut part and is 5.0 mm or less (one side)
Δ: The maximum width of rust and swelling exceeds 5.0 mm from the cut part and is 10.0 mm or less (one side)
X: The maximum width of rust and swelling exceeds 10.0 mm from the cut part (one side)

  Tables 17 to 19 show the evaluation results of the films obtained with the compositions of Examples 1 to 64 and Comparative Examples 1 to 16. In Examples 1 to 64, the wearability with electrodeposition and the appearance of the coating film obtained at all levels were good, and both were achieved. In the anticorrosion test, good results were shown. The stability of the obtained emulsion was also excellent. On the other hand, Comparative Examples 1 to 16 were inferior in all of the electrodepositability, coating appearance, and corrosion resistance. In Tables 17 to 19, “Bi ion concentration (ppm)” is the content (mg / L) of soluble Bi as metal Bi element, and “water-soluble metal compound (ppm)” Is the content (mg / L) of the water-soluble metal compound (D) as a metal element.

From the above, the effects of the present invention are clear.

Claims (11)

Cationic electrodeposition coating composition comprising a resin emulsion containing an amino group-modified epoxy resin (A) and a curing agent (B) capable of crosslinking the amino group-modified epoxy resin (A), and a soluble Bi (C) A thing,
The amino group-modified epoxy resin (A) is obtained by reacting an epoxy resin (A1) with an amine compound (A2),
The epoxy resin (A1) is
A propylene oxide-added diepoxy resin (a1) represented by the formula (1);
A bisphenol compound (a2);
A diepoxy resin (a3) different from the formula (1);
A dicarboxylic acid (a4) in which two carboxyl groups are bonded via at least one carbon atom;
A cationic electrodeposition coating composition obtained by reacting.

[In Formula (1), R1 may have a C3-C10 alkylene group which may have a substituent, a cyclohexylene group which may have a substituent, and a substituent. A phenylene group, or -Ra-Rb-Rc-, wherein Ra and Rc are a cyclohexylene group or a phenylene group, Rb is a methylene group optionally having one or two substituents; m and n are mutually independent and are any integers of 1-20] The cationic electrodeposition coating composition of Claim 1 whose said diepoxy resin (a3) is a compound shown by Formula (2).

[In Formula (2), R 3 and R 4 are each independently selected from a single bond, an alkylene group, a phenylene group, and a cyclohexylene group, and X ₁ and Y ₁ are each independently selected from a hydrogen atom and an alkyl group. ] R1 of the propylene oxide-added diepoxy resin (a1) is any one of a biscyclohexylene group represented by the formula (3), a bisphenylene group represented by the formula (4), and a phenylene group represented by the formula (5). The cationic electrodeposition coating composition according to claim 1, wherein the cationic electrodeposition coating composition is a seed and m and n in the formula (1) are independent of each other and are integers of 1 to 5.

[In the formulas (3), (4) and (5), X ₂ , X ₃ , Y ₂ and Y ₃ are independently selected from a hydrogen atom, an alkyl group and a phenyl group, and X ₄ and Y ₄ are Independently selected from hydrogen atom, alkyl group, phenyl group, alkoxyl group and hydroxyl group]   The dicarboxylic acid (a4) is a compound in which two carboxyl groups are bonded via an alkylene group having 1 to 20 carbon atoms, and the alkylene group has an alkyl group, an alkenyl group, an alkadienyl group, or a methylene group. In addition, when the alkylene group has 2 to 20 carbon atoms, a ring may be formed through adjacent carbon atoms, and the ring is selected from an alkyl group and an alkenyl group. Or the cationic electrodeposition coating composition as described in any one of Claim 1 to 3 which may have a 2 or more substituent.   The epoxy equivalent of the epoxy resin (A1) is 1000 to 5000, and the amine value of the amino group-modified epoxy resin (A) is 5 to 30, according to any one of claims 1 to 4. Cationic electrodeposition coating composition.   The amount of the propylene oxide-added diepoxy resin (a1) is 1 with respect to the total mass of the propylene oxide-added diepoxy resin (a1), the bisphenol compound (a2), the diepoxy resin (a3), and the dicarboxylic acid (a4). The cationic electrodeposition coating material according to any one of claims 1 to 5, wherein the amount of the dicarboxylic acid (a4) is 1 to 20% by mass with respect to the total mass. Composition.   The cationic electrodeposition coating composition according to any one of claims 1 to 6, wherein the curing agent (B) is a blocked polyisocyanate type curing agent.   The cationic electrodeposition coating composition according to any one of claims 1 to 7, wherein the cationic electrodeposition coating composition contains 10 to 10,000 mg / L of soluble Bi (C) as a metal Bi element. object. Furthermore, 1 to 2 or more types of water-soluble metal compounds (D) selected from the group consisting of Zr, Ti and Hf are contained in a total amount of 10 to 10,000 mg / L as metal elements. The cationic electrodeposition coating composition according to claim 1. A metal to be treated is immersed in the cationic electrodeposition coating composition according to any one of claims 1 to 9, and Bi is a main component on the metal to be treated by being immersed for 3 to 600 seconds without being energized. A metal surface treatment method comprising a step of forming a film, and then forming a coating film mainly composed of the amino group-modified epoxy resin and the curing agent on the film by cathodic electrolysis.   A coated article obtained by immersing a metal coating not subjected to chemical conversion treatment in the cationic electrodeposition coating composition according to any one of claims 1 to 9, and performing electrodeposition coating.