JP2014214223A - Cationic electrodeposition coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cationic electrodeposition coating composition excellent in coating stability, throwing power properties, and corrosion resistance, and a coated article excellent in various coating film performances.SOLUTION: A cationic electrodeposition coating composition contains 3-50 mass% of a modified epoxy resin (A), 20-70 mass% of an amino group-containing epoxy resin (B), and 10-40 mass% of a blocked polyisocyanate curing agent (C), based on the total mass of a solid content of the (A) component, (B) component and (C) component.

Description

  The present invention relates to a cationic electrodeposition coating composition that is excellent in coating stability, throwing power, and corrosion resistance.

  Cationic electrodeposition coating compositions are widely used as primer coatings for conductive metal products such as automobile bodies that require these performances due to excellent coating workability and good corrosion resistance of the formed coating film. Yes.

  Conventionally, the strength of an automobile body has been increased from the viewpoint of improving collision safety, and a reinforcing material is further added to a member welded by spot welding, so that the number of objects to be coated having a complicated bag portion has increased. In such a complicated structure, since the current density (mA / cm 2) during electrodeposition coating is reduced, the coating film is difficult to deposit, and it is likely to be unpainted. The deterioration of corrosion resistance under severe corrosive environment was remarkable. However, in order to ensure the film thickness of the bag (improvement of the so-called “throwing power”), if the coating voltage is increased and the coating is performed, the finishing performance is reduced. There was a problem such as an increase.

For this reason, various electrodeposition coatings have conventionally been proposed for the purpose of improving the stability, throwing power, and corrosion resistance of the coating. For example, a polyol-modified amino group-containing epoxy resin obtained by reacting an epoxy resin with a polyol compound obtained by adding caprolactone to a compound containing a plurality of active hydrogen groups and an amino group-containing compound is used as a vehicle component. Cationic coating compositions are disclosed. (Patent Document 1).
However, the cationic electrodeposition coating composition described in Patent Document 1 could not sufficiently satisfy the throwing power of the coating film.

  In addition, a polyol-modified amino group-containing epoxy resin obtained by reacting an epoxy compound with an acidic compound (at least one compound selected from specific phenols and specific carboxylic acids), a polyol compound, and an amino group-containing compound There has been disclosed a cationic electrodeposition coating composition containing as a resin component (Patent Document 2).

  Also disclosed is a cationic electrodeposition coating composition comprising, as a resin component, a xylene formaldehyde resin-modified amino group-containing epoxy resin obtained by reacting an epoxy resin with a xylene formaldehyde resin and an amino group-containing compound. (Patent Document 3).

  However, the cationic electrodeposition coating compositions described in Patent Document 2 and Patent Document 3 were unable to satisfy throwing power and corrosion resistance.

  From such a background, there has been a demand for a cationic electrodeposition coating composition that satisfies all the performances of coating stability, throwing power, and corrosion resistance.

JP 2001-279168 A JP 2002-188049 A JP 2003-221547 A

  An object of the present invention is to provide a cationic electrodeposition coating composition excellent in coating stability, throwing power and anticorrosion properties, and to provide a coated article excellent in these various performances.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have used two types of base resins, a specific modified epoxy resin (A) and an amino group-containing epoxy resin (B), in combination with basic strength and affinity. It is possible to solve the above problems by using a cationic electrodeposition coating composition in which the content of the resin (A), the resin (B), and the blocked polyisocyanate curing agent (C) is adjusted in order to optimize the aqueous property. The headline and the present invention were completed.

That is, the present invention provides the following cationic electrodeposition coating composition and a coated article obtained by electrodeposition coating of the cationic electrodeposition coating composition.
Item 1. Modified epoxy resin (A1) obtained by reacting epoxy resin (a1) with polyhydric alcohol (a2), and reacting epoxy resin (a1) with polyhydric alcohol (a2) and modifier (a3) A cationic electrodeposition coating composition containing at least one modified epoxy resin (A) selected from the resulting modified epoxy resin (A2), an amino group-containing epoxy resin (B) and a blocked polyisocyanate curing agent (C), Because
Based on the total solid mass of the component (A), the component (B) and the component (C), the modified epoxy resin (A) 3 to 50% by mass, the amino group-containing epoxy resin (B) 20 to 70% by mass, A cationic electrodeposition coating composition comprising a blocked polyisocyanate curing agent (C) in a proportion of 10 to 40% by mass.
Item 2. In the modified epoxy resin (A), the functional groups of the epoxy resin (a1) and the polyhydric alcohol (a2) are [molar equivalent of the epoxy group of the epoxy resin (a1)] / [hydroxyl group of the polyhydric alcohol (a2)]. The cationic electrodeposition coating composition according to Item 1, wherein the molar equivalent] is 1.0 / 0.7 to 1.0 / 4.0.
Item 3. Item 3. The cationic electrodeposition coating composition according to item 1 or 2, wherein the polyhydric alcohol (a2) is a dihydric alcohol represented by the following formula (1).
OH-R-OH formula (1)
(R in Formula (1) is an organic group having 2 to 10 carbon atoms, and may contain a hetero atom such as a nitrogen atom, an oxygen atom or a sulfur atom in addition to a carbon atom and a hydrogen atom. Is)
Item 4. A coated article obtained by immersing a metal coating in an electrodeposition coating bath of the cationic electrodeposition coating composition according to any one of Items 1 to 3, and performing electrodeposition coating.

  The cationic electrodeposition coating composition of the present invention ensures good coating stability, and the coating obtained by electrodeposition coating of the cationic electrodeposition coating composition is excellent in throwing power and anticorrosion properties. . Specifically, an automobile coated with the coating composition of the present invention has little corrosion deterioration of the paint film on the automobile body even if it runs for a long time in an environment where snow melting salt is dispersed. Furthermore, in the coating line, since the coating stability is good and the generation of aggregates is reduced, there is little blockage of the ultrafiltration membrane (UF filter).

FIG. 3 is a model diagram of a “four-sheet throwing power test jig” used for a throwing power test. The electrodeposition coating state in the throwing power test is shown.

  The present invention relates to a cationic electrodeposition coating composition comprising a modified epoxy resin (A), an amino group-containing epoxy resin (B) and a blocked polyisocyanate curing agent (C). Details will be described below.

Modified epoxy resin (A)
The modified epoxy resin (A) contained in the cationic electrodeposition coating composition of the present invention is a modified epoxy resin (A1) obtained by reacting an epoxy resin (a1) with a polyhydric alcohol (a2), and an epoxy resin. It is at least one modified epoxy resin selected from a modified epoxy resin (A2) obtained by reacting (a1), a polyhydric alcohol (a2) and a modifier (a3).

Epoxy resin (a1)
The epoxy resin (a1) which is a raw material of the modified epoxy resin (A) used in the present invention is a compound having at least one, preferably two or more epoxy groups in one molecule, and the number average molecular weight thereof is 300 to 4. It is suitable that the epoxy equivalent is in the range of 180 to 2,500, preferably in the range of 400 to 1,500, in particular, the reaction between the polyphenol compound and epihalohydrin. Is preferably obtained.

  Examples of the polyphenol compound used for forming the epoxy resin (a1) include bis (4-hydroxyphenyl) -2,2-propane [bisphenol A] and bis (4-hydroxyphenyl) methane [bisphenol F]. 4,4′-dihydroxybenzophenone, bis (4-hydroxyphenyl) -1,1-ethane, bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-3-tert-butyl-phenyl) ) -2,2-propane, bis (2-hydroxynaphthyl) methane, tetra (4-hydroxyphenyl) -1,1,2,2-ethane, 4,4′-dihydroxydiphenylsulfone, phenol novolak, cresol novolak, etc. These can be used alone or in combination of two or more. Together it can be used.

  Moreover, as an epoxy resin (a1) obtained by reaction of a polyphenol compound and epichlorohydrin, the resin of the following formula induced | guided | derived from bisphenol A is suitable especially.

Here, what is shown by n = 0-8 is suitable.
Examples of such commercially available epoxy resin (a1) include those sold by Mitsubishi Chemical Corporation under the trade names jER828EL, jER1001, jER1002, jER1004, and jER1007.

  The epoxy resin (a1) is, for example, a resin obtained by condensing an epichlorohydrin and a polyphenol compound to a high molecular weight in the presence of a catalyst such as an alkali catalyst, if necessary, an epichlorohydrin and a polyphenol compound, if necessary In the presence of a catalyst such as a catalyst, it may be condensed into a low molecular weight epoxy resin, and any of the resins obtained by polyaddition reaction of this low molecular weight epoxy resin and bisphenol may be used. Can be used alone or in combination of two or more.

Polyhydric alcohol (a2)
The polyhydric alcohol (a2) that is a raw material of the modified epoxy resin (A) used in the present invention is not particularly limited as long as it is a polyhydric alcohol component having reactivity with the epoxy resin (a1). For example, ethylene glycol , Diethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexane Diol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,3-propanesiol, 3-methyl-1,5-pentanediol, 2-methylpentane- 2,4-diol, 2,2,4-trimethyl-1,3-pentanediol, triethylene glycol 2-butyl-2-ethyl-1,3-propanediol, tricyclodecane dimethanol, triethylene glycol, neopentyl glycol, 1,4-cyclohexanediol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedi Dihydric alcohols such as methanol, hydrogenated bisphenol A and hydrogenated bisphenol F; polyether diols such as polyethylene glycol, polypropylene glycol and polybutylene glycol; glycerin, trimethylolpropane, tris (2-hydroxyethyl) isocyanurate, etc. Examples include trihydric alcohols; tetrahydric alcohols such as pentaerythritol; polymers such as polyester polyols and acrylic polyols. These may be used alone or in combination of two or more. It can be. Especially, since it is calculated | required that it is a comparatively hydrophobic compound from a viewpoint of throwing power and anticorrosion property, the said polyhydric alcohol (a2) is chosen from the dihydric alcohol represented by following formula (1). At least one type is preferable, and R in the formula (1) is more preferably a linear, branched and / or cyclic hydrocarbon group having 4 to 8 carbon atoms, and 1,6- Hexanediol, 1,4-cyclohexanedimethanol, and neopentyl glycol are more preferable.
OH-R-OH formula (1)
(R in Formula (1) is an organic group having 2 to 10 carbon atoms, and may contain a hetero atom such as a nitrogen atom, an oxygen atom or a sulfur atom in addition to a carbon atom and a hydrogen atom. Is)
Denaturant (a3)
The modified epoxy resin (A) used in the present invention can react the epoxy resin (a1), the polyhydric alcohol (a2), and, if necessary, the modifier (a3). Such a modifier (a3) is not particularly limited as long as it has reactivity with the epoxy resin (a1) and is a compound other than the polyhydric alcohol (a2). For example, acetic acid, propionic acid, Acidic compounds such as butyric acid, valeric acid, acrylic acid, oleic acid, glycolic acid, lactic acid, benzoic acid, gallic acid, fatty acid, dibasic acid; methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, Monohydric alcohols such as pentanol, hexanol, n-octanol, 2-ethylhexanol, dodecyl alcohol, stearyl alcohol, benzyl alcohol; phenol, cresol, ethylphenol, para-tert-butylphenol, nonylphenol, catechol, resorcinol, 4-tert -Butylcate Phenols such as diols; lactones such as γ-butyrolactone and ε-caprolactone; isocyanate compounds such as hexamethylene diisocyanate and isophorone diisocyanate, or cyclized polymers thereof (for example, isocyanurates) or biuret type adducts; xylene formaldehyde A compound etc. are mentioned, These can be used individually by 1 type or in combination of 2 or more types. Of these, monohydric alcohols and / or phenols are preferable.
The modifier (a3) preferably contains substantially no amine compound in order to lower the polarity of the resin, and the amine value of the modified epoxy resin (A) is 10 mgKOH / g or less. Is preferably 5.0 mgKOH / g or less, and most preferably 0 mgKOH / g.

  In the cationic electrodeposition coating composition of the present invention, the modified epoxy resin (A) used as the resin component contains the epoxy resin (a1), the polyhydric alcohol (a2), and, if necessary, the modifier (a3). It can be produced by reacting in a manner known per se.

  The reaction of the epoxy resin (a1) with the polyhydric alcohol (a2) and the modifier (a3) used as necessary is usually carried out in a suitable organic solvent, optionally in the presence of a catalyst. It can be carried out at a temperature of ˜250 ° C., preferably 70 to 200 ° C., for about 1 to 25 hours, preferably about 1 to 12 hours.

  Examples of the organic solvent include hydrocarbons such as toluene, xylene, cyclohexane, and n-hexane; esters such as methyl acetate, ethyl acetate, and butyl acetate; acetone, methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone. Ketone type; Amide type such as dimethylformamide and dimethylacetamide; or a mixture thereof. Moreover, as a reaction catalyst, although a well-known thing can be used suitably, it is preferable to use at least 1 sort (s) of amine compounds (for example, dimethylbenzylamine etc.).

The proportion of each reaction component in the above reaction can be appropriately changed according to the application of the coating composition, etc., but from the viewpoint of corrosion resistance, throwing power, etc. [molar equivalent of epoxy group of epoxy resin (a1)] / [The molar equivalent of the hydroxyl group of the polyhydric alcohol (a2)] is usually preferably in the range of 1.0 / 0.7 to 1.0 / 4.0, 1.0 / 1.05 to 1.0. /3.5 is more preferable, 1.0 / 1.4 to 1.0 / 3.0 is more preferable, and 1.0 / 1.8 to 1.0 / 2.4 is more preferable. Particularly preferred. When the modifier (a3) is used, the modifier (a3) to be blended based on the total solid mass of the epoxy resin (a1), the polyhydric alcohol (a2), and the modifier (a3) is: Usually, 25 mass% or less, preferably 1 to 10 mass% is suitable.
The number average molecular weight of the modified epoxy resin (A) is usually in the range of 1,000 to 7,000, more preferably in the range of 1,300 to 5,000, from the viewpoint of throwing power and corrosion resistance. In particular, it is particularly preferable to be within the range of 1,600 to 4,000.

  In this specification, the number average molecular weight and the weight average molecular weight are the retention time (retention capacity) measured using a gel permeation chromatograph (GPC) and the retention time of a standard polystyrene with a known molecular weight measured under the same conditions. (Retention capacity) is a value obtained by converting to the molecular weight of polystyrene. Specifically, “HLC8120GPC” (trade name, manufactured by Tosoh Corporation) is used as a gel permeation chromatograph, and “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL” are used as columns. ”And“ TSKgel G-2000HXL ”(trade names, all manufactured by Tosoh Corporation), and can be measured under the conditions of mobile phase tetrahydrofuran, measurement temperature 40 ° C., flow rate 1 mL / min, and detector RI. it can.

Amino group-containing epoxy resin (B)
The amino group-containing epoxy resin (B) used in the present invention can be obtained by reacting the epoxy resin (b1), the amine compound (b2), and, if necessary, a modifier (b3). (1) Adducts of epoxy resins and primary amine compounds, secondary amine compounds, or primary and secondary mixed amine compounds (see, for example, US Pat. No. 3,984,299); (2) An adduct of an epoxy resin and a ketiminated amine compound (see, for example, US Pat. No. 4,017,438); (3) an epoxy resin and a hydroxy compound having a ketiminated primary amino group; And the like (for example, see JP-A-59-43013).

Epoxy resin (b1)
The epoxy resin (b1) which is a raw material of the amino group-containing epoxy resin (B) used in the present invention is a compound having at least one, preferably two or more epoxy groups in one molecule. The thing similar to the epoxy resin (a1) described by description of A) can be used conveniently.

Amine compound (b2)
The amine compound (b2) which is a raw material of the amino group-containing epoxy resin (B) used in the present invention is not particularly limited as long as it is an amine compound having reactivity with the epoxy resin (b1). For example, monomethylamine , Mono-alkylamines such as dimethylamine, monoethylamine, diethylamine, dipropylamine, dibutylamine, dihexylamine, dioctylamine, monoisopropylamine, diisopropylamine, monobutylamine, monooctylamine, methylbutylamine, dibutylamine or di- Alkylamine; monoethanolamine, N-methylethanolamine, N-ethylethanolamine, diethanolamine, mono (2-hydroxypropyl) amine, di (2-hydroxypropyl) amine, N-butylethanol Ruamine, dipropanolamine, monomethylaminoethanol, N- (2-hydroxypropyl) ethylenediamine, 3-methylamine-1,2-propanediol, 3-tert-butylamino-1,2-propanediol, N-methylglu Alkanolamines such as camin and N-octylglucamine; polymethylenediamine, polyetherdiamine, ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, trimethylhexamethylenediamine, dimethylaminopropylamine, diethylenetriamine, diethylaminopropylamine, dipropylene Triamine, dibutylene triamine, bis (hexamethylene) triamine, bis (4-aminobutyl) amine, triethylenetetramine, tetraethylenepenta And alkylene polyamines such as pentaethylenehexamine; mensendiamine, isophoronediamine, bis (4-amino-3-methylcyclohexyl) methane, metaxylylenediamine, metaphenylenediamine, naphthylenediamine, dimethylaminomethylbenzene, etc. Aromatic or alicyclic polyamines; polyamines having a heterocyclic ring such as piperazine, 1-methylpiperazine, 3-pyrrolidinol, 3-piperidinol, 4-pyrrolidinol; 1-30 epoxy group-containing compounds with respect to 1 mol of the polyamine. Epoxy-added polyamines obtained by mole addition; polyamides produced by condensation of the above polyamines with aromatic acid anhydrides, cycloaliphatic acid anhydrides, aliphatic acid anhydrides, halogenated acid anhydrides and / or dimer acids Resin molecule Polyamide polyamines containing one or more primary or secondary amines in them; Ketiminated amines obtained by reacting one or more primary or secondary amines in the above polyamines with a ketone compound; These can be used singly or in combination of two or more. In addition, it is preferable that the said amine compound (b2) is a ketiminated amine compound from a viewpoint of the corrosion resistance obtained.

Denaturant (b3)
In the production of the amino group-containing epoxy resin (B) of the present invention, the modifier (b3) used as necessary is not particularly limited as long as it has reactivity with the epoxy resin (b1). Among the polyhydric alcohol (a2) and the modifier (a3) described in the description of the modified epoxy resin (A), one kind can be used alone, or two or more kinds can be used in combination. Especially, it is preferable that it is at least 1 sort (s) chosen from the dihydric alcohol represented by said Formula (1), and 1, 6- hexanediol, 1, 4- cyclohexane dimethanol, and neopentyl glycol are more preferable.

  The amino group-containing epoxy resin (B) is usually prepared by combining the epoxy resin (b1), the amine compound (b2), and, if necessary, a modifier (b3) in a suitable organic solvent and optionally a catalyst. Can be synthesized by reacting at a temperature of 60 to 250 ° C., preferably 70 to 200 ° C. for about 1 to 25 hours, preferably about 1 to 12 hours.

  When the modifier (b3) is used, the reaction order of the epoxy resin (b1), the amine compound (b2) and the modifier (b3) is not particularly limited, and the amine compound (b2) with respect to the epoxy resin (b1). And the modifier (b3) can be reacted in the reaction vessel simultaneously or one by one.

  Examples of the organic solvent include hydrocarbons such as toluene, xylene, cyclohexane, and n-hexane; esters such as methyl acetate, ethyl acetate, and butyl acetate; acetone, methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone. Examples include ketones; amides such as dimethylformamide and dimethylacetamide; and mixtures of these organic solvents. Moreover, as a reaction catalyst, although a well-known thing can be used suitably, it is preferable to use at least 1 sort (s) of amine compounds (for example, dimethylbenzylamine etc.).

  The ratio of [molar equivalent of epoxy group of epoxy resin (b1)] / [number of moles of amine compound (b2) + number of moles of modifier (b3)] is from the viewpoint of coating stability, throwing power and corrosion resistance. , Preferably in the range of 1.0 / 0.5 to 1.0 / 1.5, more preferably in the range of 1.0 / 0.8 to 1.0 / 1.3, More preferably, it is in the range of 1.0 / 0.85 to 1.0 / 1.2.

  The amino group-containing epoxy resin (B) thus obtained has an amine value of 15 to 80 mgKOH / g, preferably 30 to 65 mgKOH / g, and a number average molecular weight of 1,500 to 5,000, preferably 2, It is desirable that it is in the range of 000 to 4,000 from the viewpoints of coating stability, throwing power and anticorrosion.

Blocked polyisocyanate curing agent (C)
The blocked polyisocyanate curing agent (C) used in the present invention is a product resulting from an addition reaction between a polyisocyanate compound and an isocyanate blocking agent. As the polyisocyanate compound used in the blocked polyisocyanate curing agent (C), 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 (isocyanate methyl) cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, isophorone diisocyanate, etc. Aromatic, aliphatic or alicyclic polyisocyanate compounds; cyclized polymers of these polyisocyanate compounds or Uretto body and the like, which may be used alone or in admixture of two or more.
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 added to the isocyanate group of the polyisocyanate compound and blocked. The blocked polyisocyanate compound produced by the addition reaction is stable at room temperature, but when heated to the baking temperature of the coating film (usually about 100 to about 200 ° C.), the blocking agent dissociates to regenerate free isocyanate groups. It is desirable.

  As the isocyanate blocking agent, known ones can be used, for example, oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenol compounds such as phenol, para-t-butylphenol and cresol; n-butanol, 2 -Alcohol compounds such as ethyl hexanol, phenyl carbinol, methyl phenyl carbinol, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, ethylene glycol, propylene glycol; lactam compounds such as ε-caprolactam and γ-butyrolactam; dimethyl malonate Active methylene compounds such as diethyl malonate, dipropyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone, etc. These can be used alone or in combination of two or more.

Cationic electrodeposition coating composition The content of the modified epoxy resin (A), amino group-containing epoxy resin (B) and blocked polyisocyanate curing agent (C) in the coating composition of the present invention includes the component (A), ( B) Component (A) is usually 3 to 50% by mass, preferably 12 to 45% by mass, and component (B) is usually 20 to 70% by mass, based on the total solid mass of component (B) and component (C). Preferably it is 25-55 mass%, and a component (C) is 10-40 mass% normally, Preferably it exists in the range of 15-35 mass%.

  When the amount of the modified epoxy resin (A) is 3% by mass or more, the throwing power is good, and when it is 50% by mass or less, the coating stability is good. When the blending amount of the amino group-containing epoxy resin (B) is 20% by mass or more, the coating stability is good, and when it is 70% by mass or less, the corrosion resistance and throwing power are good. Furthermore, when the blended amount of the blocked polyisocyanate curing agent (C) is 10% by mass or more, the anticorrosion property is good, and when it is 40% by mass or less, the paint stability is good.

  The cationic electrodeposition coating composition of the present invention uses a hydrophobic modified epoxy resin (A) and a hydrophilic amino group-containing epoxy resin (B) as a base resin, so that the paint stability is relatively low. The sex is secured. Therefore, the amine value of the entire mixture of the resin (A), the resin (B), and the curing agent (C) is 8 to 30 mgKOH / g from the viewpoint of coating stability, throwing power, and corrosion resistance. Preferably, it is 10-25 mgKOH / g. If the amine value of the entire resin mixture is less than 8 mgKOH / g, the coating stability may be inferior, and if it exceeds 30 mgKOH / g, the throwing power and anticorrosion may be inferior.

  In addition, although the manufacturing method of the cationic electrodeposition coating composition of this invention is not specifically limited, For example, various additives, such as surfactant and a surface conditioner, and a pigment are added to the said component as needed. It can be obtained by mixing a dispersion paste, water, an organic solvent, a neutralizing agent, etc., and making it water-soluble or water-dispersed.

  As the neutralizing agent, known organic acids and inorganic acids can be used without particular limitation, and formic acid, lactic acid, acetic acid or a mixture thereof is particularly preferable.

  The pigment dispersion paste is prepared by previously dispersing pigments such as colored pigments, rust preventive pigments and extender pigments into fine particles. For example, a pigment dispersing resin, a neutralizing agent and pigments are blended, and a ball mill, a sand mill, or the like. The pigment dispersion paste can be prepared by dispersing in a dispersion mixer such as a pebble mill.

  As the pigment dispersion resin, known resins can be used without any particular limitation. For example, epoxy resins and acrylic resins having a hydroxyl group and a cationic group, surfactants, tertiary amine type epoxy resins, quaternary ammonium salt type epoxy resins. A tertiary sulfonium salt type epoxy resin, a tertiary amine type acrylic resin, a quaternary ammonium salt type acrylic resin, a tertiary sulfonium salt type acrylic resin, or the like can be used.

  As the above-mentioned pigments, known pigments can be used without particular limitation, for example, colored pigments such as titanium oxide, carbon black, bengara, etc .; extender pigments such as clay, mica, barita, calcium carbonate, silica; aluminum phosphomolybdate, tripolylin Anticorrosive pigments such as aluminum oxide, zinc oxide (zinc white) vanadium salt, copper, iron, manganese, magnesium, calcium salt, and the like can be added.

  Furthermore, for the purpose of corrosion inhibition or rust prevention, for example, a bismuth compound can be contained. Examples of the bismuth compound include bismuth oxide, bismuth hydroxide, basic bismuth carbonate, bismuth nitrate, bismuth silicate, and organic acid bismuth.

  For the purpose of improving the coating film curability, for example, organic tin compounds such as dibutyltin dibenzoate, dioctyltin oxide, and dibutyltin oxide can be used.

  The cationic electrodeposition coating composition of the present invention can be applied to a desired substrate surface by cationic electrodeposition. Cationic electrodeposition coating is generally diluted with deionized water or the like to have a solid content concentration of about 5 to 40% by mass, preferably 10 to 25% by mass, and a pH of 3.0 to 9.0. Preferably, the cationic electrodeposition coating composition adjusted in the range of 4.0 to 7.0 is used as a bath, usually adjusted to a bath temperature of 15 to 35 ° C., and a load voltage of 100 to 400 V, preferably 150 to 350 V. This can be done by energizing the article to be coated as a cathode. After electrodeposition coating, in order to remove the cationic electrodeposition paint that has usually adhered to the object, ultrafiltration (UF filtrate), reverse osmosis permeate (RO water), industrial water, pure water, etc. Wash thoroughly with water.

  Examples of the article to be coated include an automobile body, a motorcycle component, a household device, and other devices. In addition, as the base material of the above-mentioned object, cold-rolled steel sheet, alloyed hot-dip galvanized steel sheet, electrogalvanized steel sheet, electrolytic zinc-iron double-layer plated steel sheet, organic composite plated steel sheet, Al material, Mg material, etc. are cleaned. Those subjected to surface treatment such as complex oxide treatment, phosphate chemical treatment, chromate treatment and the like are preferable.

  Although the film thickness of an electrodeposition coating film is not specifically limited, In general, it can be in the range of 5 to 40 μm, preferably 10 to 30 μm based on the cured coating film. The coating film is baked and dried using a drying facility such as an electric hot air dryer or a gas hot air dryer at a surface temperature of the coated material of 110 to 200 ° C., preferably 140 to 180 ° C. for 10 minutes to A cured coating film can be obtained by baking and drying for 180 minutes, preferably 20 to 60 minutes.

  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 each example, “parts” indicates mass parts, and “%” indicates mass%.

Production Production Example 1 of Modified Epoxy Resin (A)
950 parts of jER1001 (trade name, manufactured by Mitsubishi Chemical Corporation, epoxy resin, epoxy equivalent 475, number average molecular weight 900) 950 parts, 152 parts of 1,3-propanediol, and 0.2 g of dimethylbenzylamine are added to a reaction vessel at 200 ° C. The reaction was continued until the epoxy equivalent reached 30,000 or more, and ethylene glycol monobutyl ether was further added to obtain a modified epoxy resin (A-1) solution having a solid content of 80%. The number average molecular weight of the modified epoxy resin (A-1) was 2,300.

Production Examples 2-6, 10-13
The modified epoxy resins (A-2) to (A-6) and (A-10) to (A-10) to (A) having a solid content of 80% were synthesized in the same manner as in Production Example 1 except that the formulation shown in Table 1 below was used. -13) A solution was obtained. In addition, the manufacture examples 10 and 13 used the modifier | denaturant (a3), and made it react with the epoxy resin (a1) in the preparation order (synthesis | combination order) similar to a polyhydric alcohol (a2).

Production Example 7
608 parts of jER828EL (trade name, manufactured by Mitsubishi Chemical Corporation, epoxy resin, epoxy equivalent 190, number average molecular weight 380), 137 parts of bisphenol A, and 0.2 part of dimethylbenzylamine were added to the reaction vessel, and the epoxy equivalent was 370 at 140 ° C. The reaction was continued until Next, 236 parts of 1,6-hexanediol was added and reacted at 130 ° C. until the epoxy equivalent reached 30,000 or more. Further, ethylene glycol monobutyl ether was added, and a modified epoxy resin having a solid content of 80% (A-7) A solution was obtained. The number average molecular weight of the modified epoxy resin (A-7) was 2,000.

Production Examples 8 and 9
The modified epoxy resins (A-8) and (A-9) having a solid content of 80% were obtained by synthesizing in the same manner as in Production Example 7 except that the formulation shown in Table 1 below was used.

尚、上記表中の配合量は、固形分（質量部）を表す。
（注１）［エポキシ樹脂（ａ１）のエポキシ基のモル当量］／［多価アルコール（ａ２）の水酸基のモル当量］
アミノ基含有エポキシ樹脂（Ｂ）の製造
製造例１４
反応容器に、ｊＥＲ１００１ ９５０部、１，６−ヘキサンジオール１５３部、ジメチルベンジルアミン０.２部を加えて２４０℃で反応させ、次いで１２０℃でジエチレントリアミンのケチミン化物５３．４部、ジエタノールアミン５２．５部を加え、エポキシ当量が３０，０００以上になるまで反応させ、更にエチレングリコールモノブチルエーテルを加え、固形分８０％のアミノ基含有エポキシ樹脂（Ｂ−１）溶液を得た。アミノ基含有エポキシ樹脂（Ｂ−１）の数平均分子量は３，４００、アミン価４１．８ｍｇＫＯＨ／ｇであった。

In addition, the compounding quantity in the said table | surface represents solid content (mass part).
(Note 1) [Molar equivalent of epoxy group of epoxy resin (a1)] / [Mole equivalent of hydroxyl group of polyhydric alcohol (a2)]
Production example 14 of amino group-containing epoxy resin (B)
In a reaction vessel, 950 parts of jER1001, 153 parts of 1,6-hexanediol, and 0.2 part of dimethylbenzylamine were added and reacted at 240 ° C., and then at 120 ° C., 53.4 parts of a diethylenetriamine ketiminate and 52.5 parts of diethanolamine. Part was added and allowed to react until the epoxy equivalent reached 30,000 or more, and ethylene glycol monobutyl ether was further added to obtain an amino group-containing epoxy resin (B-1) solution having a solid content of 80%. The number average molecular weight of the amino group-containing epoxy resin (B-1) was 3,400, and the amine value was 41.8 mgKOH / g.

Production Examples 15-24
Synthesize | combined similarly to manufacture example 14 except setting it as the mixing | blending shown in the following Table 2, and also added ethylene glycol monobutyl ether, and the amino-group containing epoxy resin (B-2)-(B-11) of solid content 80% A solution was obtained.

尚、上記表中の配合量は、固形分（質量部）を表す。
（注２）［エポキシ樹脂（ｂ１）のエポキシ基のモル当量］／［アミン化合物（ｂ２）のモル数＋変性剤（ｂ３）のモル数］
ブロック化ポリイソシアネート硬化剤（Ｃ）の製造
製造例２５
反応容器中に、コスモネートＭ−２００（商品名、三井化学社製、クルードＭＤＩ、ＮＣＯ基含有率 ３１．３％）２７０部、及びメチルイソブチルケトン１２７部を加え７０℃に昇温した。この中にエチレングリコールモノブチルエーテル２３６部を１時間かけて滴下して加え、その後１００℃に昇温し、この温度を保ちながら経時でサンプリングし、赤外線吸収スペクトル測定にて未反応のイソシアネート基の吸収がなくなったことを確認し、樹脂固形分８０％の硬化剤（Ｃ）を得た。

In addition, the compounding quantity in the said table | surface represents solid content (mass part).
(Note 2) [Mole equivalent of epoxy group of epoxy resin (b1)] / [Mole number of amine compound (b2) + Mole number of modifier (b3)]
Production Example 25 of Blocked Polyisocyanate Curing Agent (C)
In a reaction vessel, 270 parts of Cosmonate M-200 (trade name, manufactured by Mitsui Chemicals, Crude MDI, NCO group content: 31.3%) and 127 parts of methyl isobutyl ketone were added and heated to 70 ° C. In this, 236 parts of ethylene glycol monobutyl ether was added dropwise over 1 hour, and then the temperature was raised to 100 ° C., sampled over time while maintaining this temperature, and absorption of unreacted isocyanate groups by infrared absorption spectrum measurement It was confirmed that the curing agent (C) having a resin solid content of 80% was obtained.

Production and Production Example 26 for Pigment Dispersing Resin
In a flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser, 450 parts of nonylphenol, 960 parts of CNE195LB (trade name, manufactured by Changchun Japan, cresol type novolac epoxy resin, glycidyl ether of novolac type phenol resin). Charge, gradually heat while mixing and stirring, and react at 160 ° C. Thereafter, 430 parts of ε-caprolactone was charged, and the temperature was raised to 170 ° C. for reaction. Further, 105 parts of diethanolamine and 124 parts of N-methylethanolamine were reacted to confirm that the epoxy value was 0, and ethylene glycol monobutyl ether was added to obtain a pigment-dispersed resin solution having a solid content of 60%. The amine value of this pigment-dispersed resin solution was 70 mg KOH / g, and the number average molecular weight was 2,200.

Production and production example 27 of pigment dispersion paste
Resin for pigment dispersion having a solid content of 60% obtained in Production Example 26 (5 parts of solid content), 14.5 parts of titanium oxide, 7.0 parts of purified clay, 0.3 part of carbon black, dioctyltin oxide 1 part, 1 part of bismuth hydroxide and 20.3 parts of deionized water were added and dispersed in a ball mill for 20 hours to obtain a pigment dispersion paste having a solid content of 55%.

Production Example 1 of Cationic Electrodeposition Paint (X)
37.5 parts (solid content 30 parts) of the modified epoxy resin (A-1) solution obtained in Production Example 1 and 50 parts of the amino group-modified epoxy resin (B-1) solution obtained in Production Example 14 ( 40 parts of solid content) and 37.5 parts of the curing agent (C) obtained in Production Example 25 (30 parts of solid content) were mixed, and 13 parts of 10% acetic acid was further mixed and stirred uniformly. While dripping water vigorously, it took about 15 minutes to obtain an emulsion having a solid content of 34%.
Next, 294 parts of the emulsion (100 parts of solid content), 52.4 parts of the 55% pigment dispersion paste obtained in Production Example 27 (28.8 parts of solid content), and 350 parts of deionized water were added, and the solid content 20 % Cationic electrodeposition paint (X-1) was produced.

Examples 2-24, Comparative Examples 1-7
Except for the composition shown in Table 3 below, an emulsion having a solid content of 34% was produced in the same manner as in Example 1, and then 294 parts of the emulsion (100 parts of solid content), 55% obtained in Production Example 27. 52.4 parts (solid content 28.8 parts) and deionized water 350 parts were added to obtain cationic electrodeposition paints (X-2) to (X-31) having a solid content of 20%.
Moreover, it evaluated by the method mentioned later. Table 3 shows the evaluation results of throwing power, corrosion resistance, and paint stability.

尚、上記表中の配合量は、固形分（質量部）を表す。
（注３）塗料中の凝集物が多く、つきまわり性及び防食性の評価ができなかった。

In addition, the compounding quantity in the said table | surface represents solid content (mass part).
(Note 3) There were many aggregates in the paint, and the throwing power and corrosion resistance could not be evaluated.

Evaluation method <Throwing power>
A hole of 8 mm in diameter was formed in four steel plates, and a “four-box method throwing test jig” (see FIG. 1) installed at intervals of 2 cm was wired as shown in FIG. Of the four steel plates in FIG. 2, the left-hand surface toward the leftmost steel plate is referred to as “A surface”, and the right-hand surface is referred to as “B surface”. Similarly, the left and right surfaces of the second steel plate from the left are “C-plane” and “D-plane”, respectively, and the left and right surfaces of the third steel plate from the left are “E-plane” and “F-plane”, respectively. The right and left surfaces of the rightmost steel plate are the “G surface” and “H surface”, respectively. Among these, the A surface is the “outer plate” and the G surface is the “inner plate”.

In the apparatus of FIG. 2, electrodeposition coating was performed at a coating bath temperature of 30 ° C., a distance of 10 cm between the A surface and the electrode, and a current-carrying time of 3 minutes at a voltage of 15 μm on the outer plate dry film thickness. The throwing power was evaluated as throwing power ratio (%) = {inner plate dry film thickness (G surface) / outer plate dry film thickness (A surface)} × 100 according to the following criteria.
A: Throwing ratio (%) = 70% or more, and throwing power is very good.
○: Throwing ratio (%) = 65% or more and less than 70%, and throwing power is good.
Δ: throwing power ratio (%) = 60% or more and less than 65%, and the throwing power is slightly poor.
X: The throwing power ratio (%) = less than 60%, and the throwing power is poor.

<Anti-corrosion>
Cold-rolled steel sheet (150mm (length) x 70mm (width) x 0.8mm (thickness)) subjected to chemical conversion treatment (Palbond # 3020, manufactured by Nippon Parkerizing Co., Ltd., trade name, zinc phosphate treatment agent) Each of the cationic electrodeposition paints obtained in Examples and Comparative Examples was electrodeposited to a dry film thickness of 15 μm and baked and dried at 170 ° C. for 20 minutes to obtain a test plate.

In order to reach the substrate of the above test plate, the coating film is cross-cut with a cutter knife, and this is subjected to a 35 ° C. salt spray test in accordance with JIS Z-2371 for 840 hours. Based on the following criteria.
A: The maximum width of rust and blisters is 2.0 mm or less (one side) from the cut part.
○: The maximum width of rust and blistering exceeds 2.0 from the cut part, and 3.0 mm or less (one side),
Δ: The maximum width of rust and blistering exceeds 3.0 mm from the cut part and 3.5 mm or less (one side),
X: The maximum width of rust and swelling exceeds 3.5 mm from the cut part.

<Paint stability>
The cationic electrodeposition paint obtained in Examples and Comparative Examples was sealed in a container at 35 ° C. and stirred for 30 days (700 rpm, diameter 3 cm blade). Thereafter, the entire amount of the cationic electrodeposition coating material was filtered through a 400 mesh filter screen, and the amount of the residue (mg / L) was measured.
A: Less than 10 mg / L,
○: 10 mg / L or more and less than 20 mg / L,
Δ: 20 mg / L or more and less than 30 mg / L,
X: 30 mg / L or more.

  It is possible to provide a cationic electrodeposition paint having excellent paint stability and a coated article having excellent throwing power and corrosion resistance.

1. Hole with a diameter of 8mm.
2 shows an outer plate (surface A) in a throwing power test jig of the four-sheet box method.
3 shows an inner plate (G surface) in a jig for testing throwing power of the four-sheet box method.
4). An electrodeposition paint bath is shown.

Claims (4)

Modified epoxy resin (A1) obtained by reacting epoxy resin (a1) with polyhydric alcohol (a2), and reacting epoxy resin (a1) with polyhydric alcohol (a2) and modifier (a3) A cationic electrodeposition coating composition containing at least one modified epoxy resin (A) selected from the resulting modified epoxy resin (A2), an amino group-containing epoxy resin (B) and a blocked polyisocyanate curing agent (C), Because
Based on the total solid mass of the component (A), the component (B) and the component (C), the modified epoxy resin (A) 3 to 50% by mass, the amino group-containing epoxy resin (B) 20 to 70% by mass, A cationic electrodeposition coating composition comprising a blocked polyisocyanate curing agent (C) in a proportion of 10 to 40% by mass.   In the modified epoxy resin (A), the functional groups of the epoxy resin (a1) and the polyhydric alcohol (a2) are [molar equivalent of the epoxy group of the epoxy resin (a1)] / [hydroxyl group of the polyhydric alcohol (a2)]. The molar electrode] = 1.0 / 0.7 to 1.0 / 4.0. The cationic electrodeposition coating composition according to claim 1, wherein: The cationic electrodeposition coating composition according to claim 1 or 2, wherein the polyhydric alcohol (a2) is a dihydric alcohol represented by the following formula (1).
OH-R-OH formula (1)
(R in Formula (1) is an organic group having 2 to 10 carbon atoms, and may contain a hetero atom such as a nitrogen atom, an oxygen atom or a sulfur atom in addition to a carbon atom and a hydrogen atom. Is)   A coated article obtained by immersing a metal coating in an electrodeposition coating bath of the cationic electrodeposition coating composition according to any one of claims 1 to 3 and performing electrodeposition coating.

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