JP2013256560A - Cathodic electrodeposition coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cathodic electrodeposition coating composition which is excellent in corrosion resistance, in particular even when a formed coating film is an electrodeposition coating film being a thin film with a dry film thickness of 15 μm and which is excellent in coating stability without using a harmful substance such as a lead compound and a chromium compound.SOLUTION: There is provided: a cathodic electrodeposition coating composition which contains an organic binder (A) containing a cationic resin (a1) and a condensation reaction product (B) of an aminosilane (b1) with a predetermined alkoxysilane compound (b2); a method for forming a coating film using the cathodic electrodeposition coating composition; and an article with an electrodeposition coating film based on the cathodic electrodeposition coating composition formed thereon.

Description

  The present invention relates to a cationic electrodeposition coating composition that exhibits excellent anticorrosion properties, and particularly exhibits excellent anticorrosion properties even on untreated steel sheets, without containing harmful substances such as lead compounds and chromium compounds.

  Cationic electrodeposition paints are used in a wide range of applications including undercoating for automobiles because of their excellent throwing power and low environmental pollution. Conventionally, cationic electrodeposition coating compositions containing lead compounds such as lead chromate, basic lead silicate, strontium chromate and / or chromium compounds have been proposed.

  However, in recent years, the use of harmful compounds such as lead compounds and chromium compounds has been restricted due to pollution problems, and even if such harmful compounds are not added, they are non-toxic or have low corrosion resistance. Cationic electrodeposition paints using toxic anticorrosive pigments have been developed and put to practical use.

For example, Patent Document 1 contains (A) a cationic amine-modified epoxy resin, (B) a blocked polyisocyanate, and (C) a divalent or trivalent metal salt of phosphorous acid. A cationic electrodeposition coating composition aimed at improving anticorrosion properties is disclosed.
Patent Document 2 discloses a cationic electrodeposition coating material containing a compound selected from a bismuth compound such as bismuth silicate and a zirconium compound, which is free from lead compounds and excellent in corrosion resistance.

Patent Documents 1 and 2 describe that an electrodeposition coating film formed on a steel sheet subjected to surface treatment is excellent in corrosion resistance even without containing harmful substances such as lead compounds and chromium compounds. However, the electrodeposition coating film having a dry film thickness of 15 μm, which is a thin film, has insufficient corrosion resistance.
Furthermore, Patent Document 3 discloses an electrodeposition coating composition comprising an aqueous resin containing an anionic group or a cationic group, which is made of polysiloxane and a polymer other than the polysiloxane, and made water-based. Has been.

  Patent Document 4 includes at least one rust-preventing component selected from the group consisting of ions of metals selected from zirconium, titanium, cobalt, vanadium, tungsten and molybdenum, oxymetal ions and fluorometal ions of the metals, In addition, an electrodeposition coating composition containing an amino group-containing resin component derived from a specific alicyclic epoxy compound is disclosed.

  The electrodeposition paints described in Patent Documents 3 and 4 are still insufficient in anticorrosion properties and long-term paint stability of an electrodeposition coating film having a dry film thickness of 15 μm as a thin film.

  Patent Document 5 discloses a cationic electrodeposition coating composition characterized by containing a cationic amine-modified epoxy resin, a blocked polyisocyanate, and a zirconium salt, which is intended to improve rust prevention. It is described that an electrodeposition coating film having excellent anticorrosion properties can be obtained without containing harmful substances such as lead compounds and chromium compounds. However, when the electrodeposition coating film with a dry film thickness of 15 μm, which is a thin film, is subjected to severe corrosion conditions, there is still a problem with anticorrosion properties, and the paint stability in the long term is still not sufficient, and further improvement is required. It was done.

Japanese Patent Laid-Open No. 9-241546 JP 2000-290542 A JP-A-11-209694 International Publication No. 2006/022426 JP 2009-46628 A

  The problem to be solved by the present invention is to prevent corrosion without using harmful substances such as lead compounds, chromium compounds, etc., even if the formed coating film is a thin film with a dry film thickness of 15 μm. And a cationic electrodeposition coating composition having excellent coating stability.

  As a result of intensive studies to solve the above problems, the present inventors have made a cationic electrodeposition coating composition in which a condensation reaction product of an aminosilane and a specific alkoxysilane compound is contained in an organic binder containing a cationic resin. As a result, the inventors have found that the above-mentioned problems can be solved, and have completed the present invention.

That is, the present invention provides an organic binder (A) containing a cationic resin (a1), an aminosilane (b1), and the following formula (R) _4-n -Si- (X) _n
(In the formula, R represents a hydrocarbon group having 1 to 18 carbon atoms which may be substituted with a non-reactive substituent, X represents an alkoxyl group, and n is an integer of 1 to 3) A cationic electrodeposition coating composition comprising a condensation reaction product (B) with at least one alkoxysilane compound (b2) represented by formula (1).

Moreover, this invention provides the coating-film formation method characterized by performing cationic electrodeposition coating to a to-be-coated article using the said electrodeposition coating composition.
Furthermore, this invention provides the article | item in which the electrodeposition coating film by the said electrodeposition coating composition was formed on the to-be-coated article.

  According to the cationic electrodeposition coating composition of the present invention, a coating having excellent anticorrosion properties, particularly without containing harmful metals such as lead compounds and chromium compounds, even if the formed coating film is a thin film having a dry film thickness of 15 μm or less. Articles can be obtained. Therefore, the cationic electrodeposition coating composition of the present invention is useful for electrodeposition coating of automobile bodies, parts thereof, electric appliances and the like.

Cationic electrodeposition coating composition The cationic electrodeposition coating composition of the present invention contains an organic binder (A) and a condensation reaction product (B).

[Organic binder (A)]
The organic binder which is the component (A) in the cationic electrodeposition coating composition of the present invention contains a cationic resin (a1) as a base resin. As the cationic resin (a1), conventionally known cationic resins for cationic electrodeposition coatings can be used. Examples of the cationic resin include a resin having a group that can be cationized in an aqueous medium such as an amino group, an ammonium base, a sulfonium base, or a phosphonium base in the molecule. Examples of the base resin generally used include resins such as epoxy resins, acrylic resins, polybutadiene resins, alkyd resins, and polyester resins.

  As the cationic resin (a1) in the organic binder (A), an amine-added epoxy resin (a11) obtained by adding an amine compound to an epoxy resin is particularly preferable.

Amine-added epoxy resin (a11)
Examples of the amine-added epoxy resin (a11) include (a) an adduct of an epoxy resin and a primary mono- and polyamine, a secondary mono- and polyamine, or a primary and secondary mixed polyamine (for example, the United States). (A) an adduct of an epoxy resin and a secondary mono- and polyamine having a ketiminated primary amino group (see, for example, US Pat. No. 4,017,438); (C) A reaction product obtained by etherification of an epoxy resin and a ketiminated hydroxy compound having a primary amino group (for example, see JP-A-59-43013).

  The epoxy resin (a) used for the production of the above amine-added epoxy resin (a11) is a compound having one or more, preferably two or more epoxy groups in one molecule, generally 200 or more, preferably 370. Epoxy equivalent having a number average molecular weight in the range of ˜4,000, more preferably in the range of 800 to 3,000, and 160 or more, preferably in the range of 180 to 2,800, more preferably in the range of 200 to 2,000. Those with a suitable are suitable.

  In this specification, the “number average molecular weight” is a value obtained from a chromatogram measured by gel permeation chromatography (GPC) based on the molecular weight of standard polystyrene according to the method described in JIS K 0124-83. is there. As the gel permeation chromatograph, “HLC8120GPC” (manufactured by Tosoh Corporation) was used. As the columns, four columns of “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL”, “TSKgel G-2000HXL” (both manufactured by Tosoh Corporation, trade name) were used, Mobile phase: Tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 cc / min, detector: under the conditions of RI.

  As the epoxy resin (a) used for obtaining the amine-added epoxy resin (a11), in particular, (1) a polyepoxide compound obtained by a reaction of a polyphenol compound and an epihalohydrin such as epichlorohydrin, or a polyphenol compound in the polyepoxide compound (2) an epoxy resin obtained by reacting a polyphenol compound with a diepoxide compound having an alkylene oxide chain in the main chain, and (3) an epoxy obtained by reacting the polyphenol compound with an epihalohydrin. An epoxy resin obtained by reacting a resin, a diepoxide compound having an alkylene oxide chain in the main chain, and a polyphenol compound is preferable. The epoxy resins (1) to (3) can be used alone or in combination of two or more.

First, the epoxy resin (1) will be described.
As the polyphenol compound that can be used for producing the epoxy resin of the above (1), those conventionally used can be used, for example, bis (4-hydroxyphenyl) -2,2- Propane [bisphenol A], 4,4-dihydroxybenzophenone, bis (4-hydroxyphenyl) methane [bisphenol F], bis (4-hydroxyphenyl) -1,1-ethane, bis (4-hydroxyphenyl) -1, 1-isobutane, bis (4-hydroxy-tert-butyl-phenyl) -2,2-propane, bis (2-hydroxynaphthyl) methane, tetra (4-hydroxyphenyl) -1,1,2,2-ethane, 4,4-dihydroxydiphenylsulfone [bisphenol S], phenol novolac, crezo For example, arnovolac.

The polyepoxide compound obtained by the reaction of the polyphenol compound with an epihalohydrin such as epichlorohydrin can be used as the epoxy resin (1). Moreover, what made the said polyphenol compound react with this polyepoxide and made high molecular weight can also be used as the epoxy resin of (1).
As the epoxy resin (1), in particular, the following general formula (II) derived from bisphenol A

[In the above formula (II), p is preferably 0 to 8. ] Is preferable.

  The epoxy resin represented by the general formula (II) can preferably have an epoxy equivalent weight in the range of 180 to 2,800, more preferably 200 to 2,000, and preferably 370 to 4,000, Are suitable for those having a number average molecular weight in the range of 800 to 3,000.

  Examples of commercially available epoxy resins include jER828EL, jER828, jER1001, jER1002, jER1004, and jER1007 manufactured by Mitsubishi Chemical Corporation.

Next, the epoxy resin (2) will be described.
As the diepoxide compound having an alkylene oxide chain in the main chain that can be used to produce the epoxy resin of (2) above, a compound represented by the following general formula (III) or the following general formula (IV) is preferably used. Can be used.

[In said formula (III), R < ⁵ > is the same or different, represents a hydrogen atom or a C1-C6 alkyl group, X represents the integer of 1-9, Y represents the integer of 1-50. ]. When Y is 2 or more, X contained in each alkylene oxide unit may be the same or different.

  The compound represented by the general formula (III) is produced by ring-opening polymerization of alkylene oxide using alkylene glycol as a starting material to obtain hydroxyl-terminated polyalkylene oxide, and then hydroxyl-terminated polyalkylene. Examples thereof include a method of reacting an epihalohydrin with an oxide and diepoxidizing, and a method of reacting an epihalohydrin with a polyether diol obtained by dehydration condensation of alkylene glycol or two or more of the alkylene glycol molecules.

  Examples of the alkylene glycol used here include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1, Examples include alkylene glycols having 2 to 10 carbon atoms such as 8-octanediol and 1,10-decanediol.

[In the above formula (IV), R ⁶ in each repeating unit is the same or different and represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and m and n which are the number of repeating units in the alkylene oxide structure portion are , M + n = 1 to 20 represents an integer. ]
Compound (IV) is produced by adding a C2-C8 alkylene oxide to bisphenol A to obtain a hydroxyl-terminated polyether compound, and then reacting the polyether compound with epihalohydrin to diepoxidize. Can be manufactured. Examples of the alkylene oxide include ethylene oxide, propylene oxide, and butylene oxide. Among these, ethylene oxide and propylene oxide are preferable.

  Examples of the diepoxy compound represented by the general formula (III) or the general formula (IV) include Denacol EX-850, EX-821, EX-830, EX-841, EX-861, EX-941, EX-920, Examples include EX-931 (Nagase ChemteX Corporation), Glicier PP-300P, BPP-350 (Sanyo Chemical Industries Co., Ltd.), and the like.

The diepoxy compounds represented by the general formula (III) and the general formula (IV) may be used alone or in combination of two or more to form an epoxy resin of (2) as an alkylene oxide chain in the main chain. It can be used as a diepoxide compound having
The epoxy resin (2) can be obtained by reacting the diepoxide compound having an alkylene oxide chain in the main chain with the polyphenol compound described in the section of the epoxy resin (1).

Next, the epoxy resin (3) will be described.
Examples of the epoxy resin obtained by the reaction of a polyphenol compound and epihalohydrin that can be used to produce the epoxy resin (3) include the epoxy resin (1).

  The diepoxide compound having an alkylene oxide chain in the main chain that can be used to produce the epoxy resin of (3) is the general formula (III) described in the section of the epoxy resin of (2). Or the diepoxy compound represented by general formula (IV) etc. can be mentioned.

  By reacting the epoxy resin obtained by the reaction of the polyphenol compound with epihalohydrin and the diepoxide compound having an alkylene oxide chain in the main chain with the polyphenol compound described in the section of the epoxy resin of (1) (3 ) Epoxy resin can be obtained.

The epoxy resin of the above (1), (2) or (3) is the one partially reacted with polyol, polyether polyol, polyester polyol, polycarboxylic acid, polyisocyanate compound, xylene formaldehyde resin, ε-caprolactone, etc. There may be.
In obtaining the epoxy resin of the above (1), (2) or (3), in order to react an epoxy resin (polyepoxide compound, diepoxide compound) with a polyphenol compound, both are mixed and appropriately used as a reaction catalyst. , Tertiary amines such as dimethylbenzylamine and tributylamine; or quaternary ammonium salts such as tetraethylammonium bromide and tetrabutylammonium bromide; and, if necessary, the reaction temperature is 80 to 200 ° C. in the presence of an organic solvent. The reaction can be carried out by reacting at 90 to 180 ° C. for 1 to 6 hours, preferably 1 to 5 hours.
As the epoxy resin (a) used to react with an amine compound to be described later to obtain an amine-added epoxy resin (a11), the epoxy resin of the above (3) is suitable, and among them, the epoxy resin of (3) is preferably used. It is described later that the ratio of the (1) epoxy resin / (2) epoxy resin to be constituted is in the range of 95/5 to 40/60, preferably 90/10 to 60/40, by mass ratio. The amine-added epoxy resin obtained by reacting with amine compounds is excellent in water dispersibility, excellent in electrodeposition coating on alloyed hot-dip galvanized steel sheet, and finish and anticorrosive properties of cationic electrodeposition coating, especially dry film The thickness is preferably 15 μm from the viewpoint of excellent finish and corrosion resistance.

The amine compound is a cationic component for introducing an amino group into the epoxy resin (a) to cationize the epoxy resin (a) to obtain an amine-added epoxy resin (a11). Those containing at least one active hydrogen to be reacted are used.
Examples of amine compounds used for such purposes include mono- or di-alkylamines such as monomethylamine, dimethylamine, monoethylamine, diethylamine, monoisopropylamine, diisopropylamine, monobutylamine, dibutylamine; Alkanol amines such as ethanolamine, diethanolamine, mono (2-hydroxypropyl) amine, di (2-hydroxypropyl) amine, monomethylaminoethanol, monoethylaminoethanol; ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, tetraethylene Alkylene polyamines such as pentamine, pentaethylenehexamine, diethylaminopropylamine, diethylenetriamine, triethylenetetramine Beauty ketimine of these polyamines; ethyleneimine, alkylene imine such as propylene imine; piperazine, morpholine, cyclic amines such as pyrazine and the like. Of these amines, amines obtained by ketiminizing primary amines can also be used.

The amine-added epoxy resin (a11) can be produced by adding the amine compound to the epoxy resin (a). The proportion of each component used in this addition reaction is not strictly limited, and can be changed as appropriate according to the use of the electrodeposition coating composition, but the epoxy resin in the production of the amine-added epoxy resin (a11). Based on the total solid mass of (a) and the amine compound, the epoxy resin (a) is 70 to 98% by mass, preferably 75 to 96% by mass, and the amine compound is 2 to 30% by mass, preferably 4 to 25%. It is suitable that it is mass%.
The above addition reaction is usually carried out in an appropriate solvent at a temperature of 80 to 170 ° C., preferably 90 to 150 ° C. for 1 to 6 hours, preferably 1 to 5 hours. Examples of the solvent in the above reaction include hydrocarbon solvents such as toluene, xylene, cyclohexane, and n-hexane; ester solvents such as methyl acetate, ethyl acetate, and butyl acetate; acetone, methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone. Ketone solvents such as dimethylformamide and dimethylacetamide; alcohol solvents such as methanol, ethanol, n-propanol and iso-propanol; aromatic alkyl alcohol solvents such as phenyl carbinol and methyl phenyl carbinol An ether alcohol compound such as ethylene glycol monobutyl ether or diethylene glycol monoethyl ether, or a mixture thereof.

Curing agent (a2)
In the composition of the present invention, the organic binder (A) contains a curing agent (a2) that can cure the cationic resin (a1), if necessary. The curing agent (a2) is preferably at least one selected from a blocked isocyanate compound and an amino resin curing agent.

  The blocked isocyanate compound is an addition reaction product of a polyisocyanate compound and an isocyanate blocking agent in an approximately chemical theoretical amount. As the polyisocyanate compound used in the blocked polyisocyanate, known compounds can be used. For example, tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,2′-diisocyanate, diphenylmethane-2, 4′-diisocyanate, diphenylmethane-4,4′-diisocyanate, crude MDI [polymethylene polyphenyl isocyanate], bis (isocyanatemethyl) cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, isophorone diisocyanate, etc. Or cycloaliphatic polyisocyanate compounds; cyclized polymers or biurets of these polyisocyanate compounds Or it may be combinations thereof.

  In particular, aromatic polyisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, and crude MDI are preferred from the viewpoint of corrosion resistance.

  On the other hand, the isocyanate blocking agent is blocked by adding to the isocyanate group of the polyisocyanate compound, and the blocked polyisocyanate compound produced by the addition is stable at room temperature, but the baking temperature of the coating film (usually about 100). When heated to ˜about 200 ° C., it is desirable that the blocking agent dissociates to regenerate free isocyanate groups.

  Examples of the blocking agent used in the blocked polyisocyanate include oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenol compounds such as phenol, para-t-butylphenol and cresol; n-butanol, 2-ethylhexanol and the like. Aliphatic alcohol compounds; aromatic alkyl alcohol compounds such as phenyl carbinol and methyl phenyl carbinol; ether alcohol compounds such as ethylene glycol monobutyl ether and diethylene glycol monoethyl ether; lactam compounds such as ε-caprolactam and γ-butyrolactam Etc.

  Examples of the amino resin curing agent that can be used as the curing agent (a2) include various amino group-containing compounds such as melamine, benzoguanamine, acetoguanamine, and urea, and various aldehyde compounds (or aldehyde supply substances) such as formaldehyde and acetaldehyde. Various amino resins having an alkylol group obtained by reacting; or reacting the amino resin having an alkylol group with various lower alcohols such as methanol, ethanol, n-butanol or i-butanol (isobutanol) Examples thereof include various alkoxyalkyl group-containing amino resins obtained by caking.

  In the composition of the present invention, the organic binder (A) can contain other organic resins in addition to the cationic resin (a1) and the curing agent (a2). Examples of other organic resins include the following phenol resins and phenolic hydroxyl group-containing resins.

Phenol resin The cationic electrodeposition coating composition of the present invention includes a phenol resin as a part of the organic binder (A) for the purpose of improving the anticorrosion and finishing properties, particularly the anticorrosion and finishing properties at a dry film thickness of 15 μm. Can be blended.

  The phenol resin is a resin obtained by condensation reaction of a phenolic compound such as phenol, cresol, bisphenol A and an aldehyde compound such as formaldehyde in the presence of an acidic catalyst or a basic catalyst. A product obtained by condensing a product with a novolac type phenol resin and a basic catalyst is called a resol type phenol resin.

  In the present invention, both a novolac type phenol resin and a resol type phenol resin can be used. In addition, a resin having a methylol group introduced therein is also included, and a phenol resin obtained by alkyl etherifying a part or all of the introduced methylol group with an alcohol having 6 or less carbon atoms can also be used.

  As the phenolic resin (C) used in the present invention, those having a hydroxyl value of 90 to 623 mgKOH / g can improve the adhesion of the obtained coating film, and have anticorrosion properties, in particular, the formed coating film is a dry film. Even a thin film having a thickness of 15 μm or less is preferable because a coating film excellent in corrosion resistance of the coating film on the untreated steel sheet can be obtained.

  Commercially available products of the above-mentioned phenol resins include SUMILITERESIN PR-HF-3, SUMILITERESIN PR-HF-6, SUMILITERESIN PR-53194, SUMILITERESIN PR-53195, SUMILITERESIN PR-HF869, SUMILITERESIN PR1592 -53153, SUMILITERESIN PR-53364, SUMILITERESIN PR-53365, SUMILITERESIN PR-50702 (above, "Sumitomo Bakelite"); PHENOLITE TD-2131, PHENOLITE TD-2106, PHENOLITE TD-20 3, PHENOLITE TD-2091, PHENOLITE TD-2090, PHENOLITE VH-4150, PHENOLITE VH-4170, PHENOLITE VH-4240, PHENOLITE KH-1160, PHENOLITE KH-1163, PHENOLITE KH-1163, PHENOLITE KH-1163, PHENOLITE KH-1163 TD-2090-60M, PHENOLITE LF-4711, PHENOLITE LF-6161, PHENOLITE LF-4871, PHENOLITE LA-7052, PHENOLITE LA-7054, PHENOLITE LA-7751, PHENOLITE LA-3056, PHENOLITE LA-1356 P Manufactured by IC Co.); Shonor BRG-555, Shoonol BRG-556, Shoonol BRG-558, Shoonol CKM-923, Shoonol CKM-983, Shoonol BKM-2620, Shoonol BRL-2854, Shoonol BRG (5590M, Shoonol CKS-3898, Shoonol CKS-3877A, Shoonol CKM-937 (manufactured by Showa Polymer Co., Ltd.), Markalinker MS-1, Markalinker MS-2, Markalinker MS-3, Marcalinker CST (manufactured by Maruzen Petrochemical Co., Ltd.); Nikanol NP-100, Nikanol P-100, Nikanol HP-150, Nikanol PR-1440 (manufactured by Fudou) It is done.

Phenolic hydroxyl group-containing resin The cationic electrodeposition coating composition of the present invention includes a part of the organic binder (A) for the purpose of improving the anticorrosion and finish, particularly the anticorrosion and finish at a dry film thickness of 15 μm. A phenolic hydroxyl group-containing resin can be blended.

  The phenolic hydroxyl group-containing resin includes an epoxy resin represented by the general formula (II) and p in the formula (II) of 0 to 2, a diepoxy compound represented by the general formula (III), and the general formula ( IV) At least one epoxide selected from the diepoxy compounds represented by IV) and the polyphenol compound, preferably a bisphenol compound described in the section of the epoxy resin of (1) above, [the total of epoxides (epoxy resin and diepoxy compound) [Epoxy group] / [phenol group of polyphenol compound] equivalent ratio = 0.5 to 0.85, preferably 0.5 to 0.83, more preferably 0.5 to 0.8 is there.

  The phenolic hydroxyl group-containing resin is usually produced by mixing the above epoxide and a polyphenol compound, and appropriately using a reaction catalyst such as a tertiary amine or a quaternary ammonium salt as the reaction catalyst, with a reaction temperature of 80. It can be obtained by reacting at -200 ° C, preferably 90-180 ° C, with a reaction time of 1-6 hours, preferably 1-5 hours.

  The phenolic hydroxyl group-containing resin thus obtained has a phenolic hydroxyl value of 20 to 112 mgKOH / g, preferably 25 to 110 mgKOH / g, and a number average molecular weight of 800 to 7,000, preferably 900 to 5,000. It is also preferable for finishing and anticorrosion properties, particularly for improving finishing properties and anticorrosion properties at a dry film thickness of 15 μm.

In the cationic electrodeposition coating composition of the present invention, the blending ratio of the cationic resin (a1) in the organic binder (A), the curing agent (a2), and other resins such as a phenol resin and a phenolic hydroxyl group-containing resin, It is within the following ranges for coating stability as coating characteristics, suitability for electrodeposition coating on galvannealed steel sheet, finish and corrosion resistance, especially finish and corrosion resistance of dry film thickness of 15 μm. This is suitable from the viewpoint of obtaining an excellent coated article.
Cationic resin (a1): 20 to 75% by mass, preferably 30 to 70% by mass,
Curing agent (a2): 10 to 40% by mass, preferably 15 to 35% by mass,
Other resins: 0 to 50% by mass, preferably 5 to 40% by mass.

Silane condensation reaction product (B)
The cationic electrodeposition coating composition of the present invention comprises aminosilane (b1) and the following formula (R) _4-n- Si- (X) _n
(In the formula, R represents a hydrocarbon group having 1 to 18 carbon atoms which may be substituted with a non-reactive substituent, X represents an alkoxyl group, and n is an integer of 1 to 3) A silane condensation reaction product (B) with at least one alkoxysilane compound (b2) represented by:

  The aminosilane (b1) is not particularly limited as long as it is a silane coupling agent having at least one primary or secondary amino group and hydrolyzable group in one molecule. The hydrolyzable group is not particularly limited, and preferred examples include an alkoxysilyl group directly bonded to silicon element.

  Specific examples of aminosilane (b1) include N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane, and N- (2-aminoethyl). Examples include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxysilane. Among these, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxysilane are used. It can be preferably used.

  The alkoxysilane compound (b2) may be a trialkoxysilane compound, a dialkoxysilane compound, or a monoalkoxysilane compound, but from the viewpoint of solubility in an aqueous medium, the trialkoxysilane compound is 80 masses. Those containing at least%, particularly those consisting of trialkoxysilane compounds are preferred.

  Examples of the trialkoxysilane compound include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, Pentiltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, methyltris (methoxyethoxy) silane, ethyltris (methoxyethoxy) silane, 3,3,3-trifluoropropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxy Examples thereof include silane, vinyltris (methoxyethoxy) silane, phenyltrimethoxysilane, and phenyltriethoxysilane. Of these, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, methyltris (methoxyethoxy) Silane and ethyltris (methoxyethoxy) silane are preferred.

  Examples of the mono- or di-alkoxysilane compound include monoalkoxysilanes such as trimethylmethoxysilane, trimethylethoxysilane, trimethylpropoxysilane, triethylmethoxysilane, and triethylethoxysilane; dimethyldimethoxysilane, dimethyldiethoxysilane, and dimethyldi Examples thereof include dialkoxysilanes such as propoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, methylethyldimethoxysilane, methylethyldiethoxysilane, and dipropyltrimethoxysilane.

  The proportion of aminosilane (b1) and alkoxysilane compound (b2) used in the condensation reaction product (B) is a molar ratio of (b1) / (b2) from the viewpoint of water resistance and corrosion resistance, and is 50/50 to 99 /. Is preferably 1, and more preferably in the range of 60/40 to 96/4.

  The silane condensation reaction product (B) of the aminosilane (b1) and the alkoxysilane compound (b2) is obtained by reacting the aminosilane (b1) and the alkoxysilane compound (b2) with (b1 It is preferable to add about 1 to 5 times the molar amount of water to the total molar amount 1 of the component (b) and the component (b2) for hydrolysis and condensation reaction. This hydrolysis and condensation reaction is an exothermic reaction, and it is preferable to suppress a rapid reaction such as gelation. For example, it is preferable to gradually add the component (b1) and the component (b2).

  The silane condensation reaction product (B) preferably has a weight average molecular weight of about 500 to 100,000, and more preferably about 1,000 to 20,000. The weight average molecular weight of the silane condensation reaction product (B) can be determined by the following light scattering method.

  Light scattering method: A method of obtaining a weight average molecular weight by making a static light scattering measurement with a Zetasizer manufactured by Malvern and creating a Zimm plot.

The blending ratio of the silane condensation reaction product (B) in the cationic electrodeposition coating composition of the present invention is 0.01 to 10 parts by mass, preferably 0 based on 100 parts by mass of the solid content of the organic binder (A). It is preferable that it is in the range of 0.1 to 1.0 part by mass.
Production of cationic electrodeposition coating composition of the present invention In production of cationic electrodeposition coating composition, cationic resin (a1), curing agent (a2), phenolic resin, phenolic hydroxyl group-containing resin blended as necessary Organic binder containing other organic resin such as (A), if necessary, after thoroughly mixing various additives such as surfactant, surface conditioner, organic solvent, etc. to prepare a compounded resin, The compounded resin can be neutralized with an organic carboxylic acid or the like, water-soluble or water-dispersed, and used as a resin emulsion. In addition, generally publicly known organic carboxylic acid can be used for neutralization of compound resin, but especially acetic acid, formic acid, lactic acid, or a mixture thereof is suitable.

  In the cationic electrodeposition coating composition of the present invention, other additives such as a pigment, a catalyst, an organic solvent, a pigment dispersant, a surface conditioner, and a surfactant are usually used in the coating field as necessary. It can contain with the compounding quantity which is. Examples of the pigments and catalysts include coloring pigments such as titanium white, carbon black, and bengara; extender pigments such as clay, mica, barita, calcium carbonate, and silica; aluminum trihydrogen phosphate, aluminum phosphomolybdate, Antirust pigments such as zinc oxide (zinc white); bismuth compounds such as bismuth oxide, bismuth hydroxide and bismuth lactate; organic tin compounds such as dibutyltin oxide and dioctyltin oxide; dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dilaurate Examples thereof include catalysts such as tin compounds such as aliphatic or aromatic carboxylates of dialkyltin such as acetate, dioctyltin dibenzoate, and dibutyltin dibenzoate.

  The pigments and catalysts such as the above-mentioned colored pigments, rust preventive pigments and extender pigments are mixed with, for example, a pigment dispersion resin, a neutralizing agent, etc. Thus, it can be used as a pigment dispersion paste dispersed in fine particles. The blending amount of these pigments is preferably in the range of 1 to 100 parts by weight, particularly 10 to 50 parts by weight, per 100 parts by weight of the solid content of the organic binder (A). The pigment dispersing resin is also included in the organic binder (A).

  As the pigment dispersion resin, known resins can be used, such as a base resin having a hydroxyl group and a cationic group, a tertiary amine type epoxy resin, a quaternary ammonium salt type epoxy resin, and a tertiary sulfonium salt type epoxy resin. Resin can be used.

  The method for producing the cationic electrodeposition coating composition of the present invention is not particularly limited as long as it is a method capable of stably producing the cationic electrodeposition coating composition of the present invention. For example, the cationic resin (a1) And resin emulsion of organic binder (A) such as curing agent (a2), pigment dispersion paste, and other ingredients as necessary, adjusted with deionized water, pH adjuster, etc., bath solid concentration Is usually 5 to 40% by mass, preferably 8 to 25% by mass, and the pH is 1.0 to 9.0, preferably 3.0 to 6.5.

  The method of forming a coating film using the cationic electrodeposition coating composition of the present invention can be carried out by a conventionally known method without any particular limitation. Specifically, the cationic electrodeposition coating composition is placed in a bath to have a bath temperature of 15 to 55 ° C., preferably 20 to 50 ° C., and the object to be coated is immersed in the bath of the cationic electrodeposition coating composition to be coated. It is preferable to energize the object as a cathode at a coating voltage of 50 to 400 V, preferably 75 to 370 V, for 60 to 600 seconds, preferably 80 to 400 seconds.

The coating object applicable to the coating film forming method of the present invention is not particularly limited as long as it has electrical conductivity. For example, a steel plate, a galvanized steel plate, alloyed zinc (iron-zinc, aluminum-zinc, Nickel-zinc) plated steel plate, copper plated steel plate, tin plated steel plate, aluminized steel plate, copper plate, aluminum plate, etc., various metal plates such as phosphate treatment, chromate treatment, complex oxide treatment, etc. A surface-treated metal plate or the like subjected to surface treatment is used.
In the coating film forming method of the present invention, after the coating film is formed by electrodeposition coating, the object to be coated is washed with water as necessary, and the surface temperature of the object to be coated is usually in a baking oven or an appropriate method such as an infrared heater. The cured coating film is formed on the article to be coated by baking usually for 5 to 90 minutes, preferably 10 to 50 minutes, so that the temperature is in the range of 100 to 200 ° C., preferably 120 to 180 ° C. be able to.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited thereto. Hereinafter, “parts” and “%” represent “parts by mass” and “% by mass” unless otherwise specified.

Production and Production Example 1 of Cationic Resin (a1) 1. Production Example 1 Into a 2-liter flask equipped with a thermometer, a reflux condenser, and a stirrer, 185 parts of Denacol EX-821 (Note 1), 950 parts of jER828EL (Note 5), 456 parts of bisphenol A and tetra 0.8 part of butylammonium bromide was added and reacted at 160 ° C. until the epoxy equivalent was 800. Next, 359 parts of methyl isobutyl ketone was added, and then 150 parts of diethanolamine and 127 parts of methyl isobutyl ketone ketiminate of diethylenetriamine (purity 84%, methyl isobutyl ketone solution) were added and reacted at 120 ° C. for 4 hours. Cationic resin No. which is an amine-added epoxy resin having a resin solid content of 80%. One solution was obtained. Cationic resin no. The resin solid content of No. 1 was an amine value of 69 mgKOH / g and a number average molecular weight of 2,400.

Production Example 2 Cationic Resin No. Production Example 2 No. 471 parts Denacol EX-931 (Note 2), 950 parts jER828EL (Note 5), 456 parts Bisphenol A and Tetra 0.8 part of butylammonium bromide was added and reacted at 160 ° C. until an epoxy equivalent of 950 was reached. Next, 430 parts of methyl isobutyl ketone was added, and then 150 parts of diethanolamine and 127 parts of a methyl isobutyl ketone ketiminate of diethylenetriamine (purity 84%, methyl isobutyl ketone solution) were added and reacted at 120 ° C. for 4 hours. Cationic resin No. which is an amine-added epoxy resin having a resin solid content of 80%. Two solutions were obtained. Cationic resin no. The resin solid content of No. 2 was an amine value of 60 mgKOH / g and a number average molecular weight of 2,500.

Production Example 3 Cationic Resin No. 3. Production Example 3 Into a 2 liter flask equipped with a thermometer, a reflux condenser, and a stirrer, 340 parts of Glicier BPP-350 (Note 4), 950 parts of jER828EL (Note 5), 456 parts of bisphenol A and tetra 0.8 part of butylammonium bromide was added and reacted at 160 ° C. until an epoxy equivalent of 900 was reached. Next, 400 parts of methyl isobutyl ketone was added, and then 150 parts of diethanolamine and 127 parts of a methyl isobutyl ketone ketiminate of diethylenetriamine (purity 84%, methyl isobutyl ketone solution) were added and reacted at 120 ° C. for 4 hours. Cationic resin No. which is an amine-added epoxy resin having a resin solid content of 80%. Three solutions were obtained. Cationic resin no. The resin solid content of No. 3 was an amine value of 64 mgKOH / g and a number average molecular weight of 2,500.

Production Example 4 Cationic Resin No. Production Example 4 Into a 2 liter flask equipped with a thermometer, reflux condenser and stirrer, 162 parts of Glicier PP-300P (Note 3), 1000 parts of jER828EL (Note 5), 440 parts of bisphenol A and tetra 1.6 parts of butylammonium bromide was added and reacted at 160 ° C. until the epoxy equivalent was 800. Next, 430 parts of methyl isobutyl ketone was added, and then 130 parts of 2-methylamino-1-ethanol was added and reacted at 100 ° C. for 4 hours. . Four solutions were obtained. Cationic resin no. The resin solid content of No. 4 was an amine value of 58 mgKOH / g and a number average molecular weight of 2,200.

Production Example 5 Cationic Resin No. Production Example 5 Into a 2 liter flask equipped with a thermometer, reflux condenser, and stirrer, 162 parts of Glicier PP-300P (Note 3), 1000 parts of jER828EL (Note 5), 440 parts of bisphenol A and tetra 1.6 parts of butylammonium bromide was added and reacted at 160 ° C. until the epoxy equivalent was 800. Next, 450 parts of methyl isobutyl ketone was added, and then 210 parts of 4-ethylamino-1-butanol was added and reacted at 100 ° C. for 4 hours, and the cationic resin No. was an amine-added epoxy resin having a resin solid content of 80%. . Five solutions were obtained. Cationic resin no. The resin solid content of No. 5 was an amine value of 56 mgKOH / g and a number average molecular weight of 2,200.

  Table 1 below shows the base resin Nos. Of Production Examples 1 to 5. 1-No. The blending content and special number of 5 are shown.

(Note) in Table 1 has the following meaning.
(Note 1) Denacol EX-821: manufactured by Nagase ChemteX Corporation, trade name, diepoxide compound represented by the above general formula (III) (in formula (III), R ⁵ = hydrogen atom, X = 1, Y = 4) , Epoxy equivalent 185,
(Note 2) Denacol EX-931: manufactured by Nagase ChemteX Corporation, trade name, diepoxide compound represented by the above general formula (III) (in formula (III), R ⁵ = CH ₃ group, X = 1, Y = 11 ), Epoxy equivalent 471,
(Note 3) Glicier PP-300P: Sanyo Chemical Industries, trade name, diepoxide compound represented by the above general formula (III) (in formula (III), R ⁵ = CH ₃ group, X = 1, Y = 7 ), Epoxy equivalent 296,
(Note 4) Glicier BPP-350: manufactured by Sanyo Chemical Industries, trade name, diepoxide compound represented by the general formula (IV) (in formula (IV), R ⁶ = CH ₃ group, m + n = 3), epoxy equivalent 340,
(Note 5) jER828EL: manufactured by Mitsubishi Chemical Corporation, trade name, bisphenol A type epoxy resin represented by the general formula (II), epoxy equivalent 190, number average molecular weight 380.

Synthesis Example 1 Production of Xylene Formaldehyde Resin 50% formalin 480 parts, phenol 110 parts, 98% industrial sulfuric acid 202 parts and metaxylene 424 in a 2 liter separable flask equipped with a thermometer, reflux condenser and stirrer The parts were charged and reacted at 84 to 88 ° C. for 4 hours. After the reaction is completed, the resin phase is separated from the sulfuric acid aqueous phase by standing, then the resin phase is washed with water three times, and unreacted metaxylene is stripped for 20 minutes under the condition of 20-30 mmHg / 120-130 ° C. 480 parts of a phenol-modified xylene formaldehyde resin having a viscosity of 1,050 mPa · s (25 ° C.) were obtained.

Production Example 6 Cationic Resin No. Production Example 6 To a flask, 1140 parts of jER828EL (Note 5), 456 parts of bisphenol A and 0.2 part of dimethylbenzylamine were added and reacted at 130 ° C. until an epoxy equivalent of 820 was reached. Next, 420 parts of methyl isobutyl ketone was added, and then 300 parts of the xylene formaldehyde resin obtained in Synthesis Example 1 was added. (Methyl isobutyl ketone solution) was added and reacted at 120 ° C. for 4 hours. 6 solutions were obtained. Cationic resin no. The resin solid content of No. 6 was an amine value of 47 mgKOH / g and a number average molecular weight of 2,500.

Production Example thermometer phenolic hydroxyl group-containing resin Production Example 7 phenolic hydroxyl group-containing resin solution, a reflux condenser, and 2-liter flask equipped with a stirrer, jER828EL (Note 5) 730 parts of bisphenol A 670 parts and 1.6 parts of tetrabutylammonium bromide were added and reacted at 160 ° C. until the epoxy value was 0.02 or less. Next, 226 parts of methyl isobutyl ketone was added to obtain a phenolic hydroxyl group-containing resin solution having a resin solid content of 80%. The resin solid content of the phenolic hydroxyl group-containing resin had a phenolic hydroxyl value of 80 mgKOH / g and a number average molecular weight of 1,400. The equivalent ratio of [epoxy group in epoxy resin] / [phenol group of bisphenol compound] = 0.65.

Production Example 8 of Curing Agent (a2) Production Example of Blocked Polyisocyanate Curing Agent In a reaction vessel, 270 parts of Cosmonate M-200 (trade name, made by Mitsui Chemicals, Crude MDI) and 127 parts of methyl isobutyl ketone were added. In addition, the temperature was raised to 70 ° C. In this, 236 parts of ethylene glycol monobutyl ether was added dropwise over 1 hour, then heated to 100 ° C., sampled over time while maintaining this temperature, and unreacted isocyanate group was measured by infrared absorption spectrum measurement. It was confirmed that the absorption of the resin was lost, and a curing agent having a resin solid content of 80% was obtained.

Production Example 9 Production Example of Pigment Dispersing Resin jER828EL (Note 5) 1,010 parts, 390 parts of bisphenol A, Plaxel 212 (polycaprolactone diol, Daicel Chemical Industries, Ltd., trade name, weight average molecular weight of about 1,250) ) 240 parts and 0.2 part of dimethylbenzylamine were added and reacted at 130 ° C. until the epoxy equivalent was about 1,090.

  Next, 134 parts of dimethylethanolamine and 150 parts of a 90% aqueous lactic acid solution were added to the reaction product, and reacted at 120 ° C. for 4 hours. Subsequently, methyl isobutyl ketone was added to the obtained reaction product to adjust the solid content, and an ammonium salt resin-based pigment dispersion resin having a solid content of 60% was obtained. The ammonium salt concentration of the resin solid content of the dispersion resin was 0.78 mmol / g.

Production Example 10 Production Example of Pigment Dispersion Paste 8.3 parts of pigment dispersion resin 60% solid content obtained in Production Example 9 (5 parts solid content), 14.5 parts titanium oxide, 7.0 parts refined clay, carbon 0.3 parts of black, 1 part of dioctyl tin oxide, 1 part of bismuth hydroxide and 20.3 parts of deionized water were mixed and dispersed in a ball mill for 20 hours to obtain a pigment dispersion paste having a solid content of 55%.

Production Example 11 of Silane Condensation Reaction Product (B)
200 parts of isopropanol and 200 parts of deionized water were charged into a 1 L round bottom flask equipped with a reflux condenser, a thermometer, a nitrogen inlet tube, and a stirrer, and stirring was started. Nitrogen was blown into the gas phase, and 80 parts of N- (2-aminoethyl) -3-aminopropyltrimethoxysilane and 20 parts of methyltrimethoxysilane were added all at once with stirring. After reacting at 60 ° C. for 6 hours, while removing the fraction, it was exchanged with propylene glycol monomethyl ether, and the temperature was raised until the boiling point became 120 ° C. Then, it concentrated and obtained the 40% of non volatile matter solution of the condensation reaction product (B1). The obtained silane condensation reaction product (B1) solution having a nonvolatile content of 40% was a colorless transparent viscous liquid, and the weight average molecular weight of the silane condensation reaction product (B1) by light scattering method was 5,500. .

Production Examples 12 to 21 (Production Examples 20 and 21 are for comparison)
A 40% non-volatile solution of each condensation reaction product (B2) to (B11) solution was obtained in the same manner as in Production Example 11 except that the raw material composition was as shown in Table 2 below.

Production and Production Example 22 of Resin Emulsion Production Example 1 Cationic Resin No. 1 obtained in Production Example 1 1 solution 62.5 parts (solid content 50 parts), phenolic hydroxyl group-containing resin No. 1 obtained in Production Example 7. 25.0 parts of 1 solution (20 parts of solid content), 37.5 parts (solid content of 30 parts) of the curing agent obtained in Production Example 8 were mixed, and 15.0 parts of 10% acetic acid were further blended. After stirring uniformly, under strong stirring, 179.0 parts of deionized water was added dropwise over about 15 minutes and stirred to give resin emulsion No. 34 having a solid content of 34%. 1 was obtained.

Production Examples 23 to 33 Resin emulsion No. 2-No. Production Example 12 Resin Emulsion No. 12 was prepared in the same manner as in Production Example 22 except that the contents shown in Table 3 below were used. 2-No. 12 was obtained. In Table 3, the values in parentheses indicate solid parts by mass.

(Note 6) Cymel 232S: manufactured by Nippon Cytec Industries, Ltd., trade name, methyl / butyl mixed etherified melamine resin, solid content 100%,
(Note 7) Shounol BRG-555: Showa Polymers, trade name, phenol resin, hydroxyl value 534 mgKOH / g.

Production Example 1 of Cationic Electrodeposition Coating Composition
Resin Emulsion No. obtained in Production Example 22 1 is 294.1 parts (solid content 100 parts), 55% pigment dispersion paste obtained in Production Example 10 is mixed with 52.4 parts (solid content 28.8 parts) and deionized water 653.5 parts. 1,000 parts bath. Next, 1.0 part (solid content 0.4 part) of the silane condensation reaction product (B1) solution was added to the bath, and the cationic electrodeposition coating composition No. 1 was obtained.

Examples 2-28 and Comparative Examples 1-10
A cationic electrodeposition coating composition No. 1 was prepared in the same manner as in Example 1 except that the formulations shown in Tables 4 to 6 below were used. 2-No. 38 was obtained. Cationic electrodeposition coating composition No. 29-No. 38 is for comparison. In Tables 4-6, the numerical value in () represents a solid content mass part.

Preparation and evaluation of a test plate on which a cationic electrodeposition coating film was formed Chemical conversion treatment (Palbond # 3020, manufactured by Nippon Parkerizing Co., Ltd., trade name, zinc phosphate treatment agent) cold-rolled steel sheet (70 mm x 150 mm x 0.8 mm) Was to be coated.

  Each cationic electrodeposition paint No. 1-No. 38 baths were adjusted to 30 ° C., the objects to be coated were immersed in each bath, and the film was energized to a dry film thickness of 15 μm based on the condition of energizing time of 180 seconds at a voltage of 200 V with the object to be coated as a cathode. After adjusting the time and performing cationic electrodeposition coating, the surface of the electrodeposition coating film was washed with water and baked at 170 ° C. for 20 minutes to obtain each test plate having a dry film thickness of 15 μm. Each test plate was evaluated according to the following test method. The test results are shown in Tables 7 to 9 below.

Test Method (Note 8) Finish: The number of pinholes in 10 cm × 10 cm was counted for the test plate:
◎: No occurrence of pinholes,
○: One small pinhole (gas dent) is observed, but it is only possible to conceal with an intermediate coating film, no problem.
Δ: 2 to 9 pinholes or 1 large pinhole
X: Ten or more pinholes are generated.

(Note 9) Resistance to warm salt water: After immersing the test plate in salt water at a concentration of 5% by weight at 50 ° C. for 600 hours, the test plate is pulled up to wipe off the water on the coating surface, and then the coating surface The cellophane adhesive tape was closely attached to the tape, and the tape was peeled off instantly. This peel test evaluated the percentage (%) of the paint film peeled:
A: Less than 5% of the coating film peeled off the test coating film part,
◯: The ratio of the peeled film to the test paint film part is 5% or more and less than 10%.
(Triangle | delta): The ratio which the coating film peeled with respect to the test coating-film part is 10% or more, and less than 20%
X: The ratio of peeling of the coating film with respect to the test coating film part is 20% or more.

(Note 10) Anticorrosion: Cross cut scratches are put on the test plate with a knife so as to reach the substrate, and this is subjected to a salt spray test at 35 ° C. for 1080 hours in accordance with JIS Z-2371. The corrosion resistance was evaluated according to the following criteria by the maximum width of rust and blister width:
A: Less than 2 mm on one side from the cut part,
◯: 2 mm or more and less than 3 mm on one side from the cut part,
Δ: 3 mm or more and less than 4 mm on one side from the cut part,
X: 4 mm or more on one side from the cut part.

(Note 11) Paint stability:
Each electrodeposition coating composition was stirred with the container sealed at 30 ° C. for 30 days. Thereafter, the total amount of each electrodeposition coating composition was filtered using a 400 mesh filter screen, and the amount of residue (mg / L) was measured;
○: Residue amount is less than 10 mg / L,
Δ: Residue amount is 10 mg / L or more and less than 15 mg / L,
X: The amount of residue is 15 mg / L or more.

(Note 12) Comprehensive evaluation: In the field of cationic electrodeposition coating to which the present invention belongs, it is desirable that the cationic electrodeposition coating is excellent in all of finish, hot salt water soaking resistance, corrosion resistance and coating stability. . In addition, it is most desirable that the above four items have the highest evaluation (◎ for finishing, hot salt water soaking and anticorrosion, and ◯ for coating stability).
Therefore, a comprehensive evaluation was performed according to the following criteria:
◎: Finishing property, hot salt water immersion property and exposure corrosion resistance are ◎, and paint stability is ◯.
○: The above four items are ◎ or ○, and ◎ is 2 or less.
Δ: The above four items are ◎, ○ or Δ, and there is at least one Δ.
×: At least one of the above four items is ×.

Claims (11)

Organic binder (A) containing cationic resin (a1), aminosilane (b1) and the following formula (R) _4-n- Si- (X) _n
(In the formula, R represents a hydrocarbon group having 1 to 18 carbon atoms which may be substituted with a non-reactive substituent, X represents an alkoxyl group, and n is an integer of 1 to 3) A cationic electrodeposition coating composition comprising a condensation reaction product (B) with at least one alkoxysilane compound (b2) represented by formula (1). The electrodeposition coating composition according to claim 1, wherein the cationic resin (a1) is an amine-added epoxy resin (a11). The electrodeposition coating composition according to claim 1 or 2, wherein the organic binder (A) contains a cationic resin (a1) and a curing agent (a2) capable of curing the cationic resin (a1). . The electrodeposition coating composition according to claim 3, wherein the curing agent (a2) is at least one curing agent selected from a blocked isocyanate compound and an amino resin curing agent. Aminosilane (b1) is N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyl The electrodeposition coating composition according to any one of claims 1 to 4, which is at least one compound selected from triethoxysilane, 3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxysilane. The alkoxysilane compound (b2) is methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, pentyltrimethyl. Methoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, methyltris (methoxyethoxy) silane, ethyltris (methoxyethoxy) silane, 3,3,3-trifluoropropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, It is at least one trialkoxysilane selected from vinyltris (methoxyethoxy) silane, phenyltrimethoxysilane and phenyltriethoxysilane. Electrodeposition coating composition according to any one claim of claim 1 to 5. The use ratio of the aminosilane (b1) and the alkoxysilane compound (b2) in the condensation reaction product (B) is 50/50 to 99/1 in a molar ratio of (b1) / (b2). The electrodeposition coating composition according to any one of the above. The electrodeposition coating composition according to any one of claims 1 to 7, wherein the condensation reaction product (B) has a weight average molecular weight of 500 to 100,000 by a static light scattering method. The solid content of the condensation reaction product (B) is in the range of 0.01 to 10 parts by mass based on 100 parts by mass of the solid content of the organic binder (A). Electrodeposition paint composition. A method for forming a coating film, comprising using the electrodeposition coating composition according to any one of claims 1 to 9 to perform cationic electrodeposition coating on an object to be coated. An article in which an electrodeposition coating film by the electrodeposition coating composition according to any one of claims 1 to 9 is formed on an object to be coated.