JP2008001788A - Anionic electrodeposition coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anionic electrodeposition coating composition which, without using harmful metals such as lead compounds and chromium compounds, forms a coating film excellent in corrosion prevention, weatherability, impact resistance, finish, low temperature curability and secondary running/popping properties. <P>SOLUTION: The anionic electrodeposition coating composition contains 50-95 parts by mass of an acrylic resin (A) containing a specific carboxy group, 5-50 parts by mass of a crosslinking agent (B) of at least one kind selected from a melamine resin and blocked isocyanate compounds, and 0.1-30 parts by mass of amorphous silica fine particles (C) that have been subjected to calcium ion exchange, based on a total 100 parts by mass of the solids of the carboxy group-containing resin (A) and the crosslinking agent (B). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a coating film excellent in anticorrosion, weather resistance, impact resistance, finish, low temperature curability, secondary sagging and cracking resistance without using harmful metals such as lead compounds and chromium compounds. The present invention relates to an anionic electrodeposition coating composition to be formed.

  Anionic electrodeposition coating compositions are used in a wide range of fields, including industrial parts and automotive parts, and have excellent coating properties such as corrosion resistance, weather resistance, impact resistance, finish, and low-temperature curability. There is a demand for being able to produce painted articles at a low cost.

  For example, conventional anionic electrodeposition coating materials include maleated resins obtained by adding maleic anhydride to dry oil (eg, linseed oil, dehydrated castor oil, tung oil, etc.), polybutadiene (1, 2, 1, 4, etc.) A maleated polybutadiene resin obtained by adding maleic anhydride to a resin, a resin obtained by adding maleic anhydride to an ester of an epoxy resin and an unsaturated fatty acid, a resin obtained by adding a polybasic acid to a high molecular weight polyhydric alcohol, A carboxyl group-containing resin such as a carboxyl group-containing polyester resin and a carboxyl group-containing acrylic resin has been disclosed (Patent Document 1). However, the electrodeposition paint described in Patent Document 1 has a drawback of insufficient corrosion resistance.

  Also, a low molecular weight polyol having a primary hydroxyl group obtained by reacting an epoxy resin having a cycloaliphatic moiety with a monocarboxylic acid and then reacting the remaining hydroxyl group with ε-caprolactone, a crosslinking agent, and optionally an ionic polymer An electrodeposition coating composition containing a molecular polyol has been disclosed (see Patent Document 2). However, it is not satisfactory in coating workability such as anti-corrosion properties, secondary sagging resistance, and warp resistance.

  In addition, an anionic electrodeposition paint containing a hydroxyl group and carboxyl group-containing resin, a crosslinking agent, a basic neutralizing agent, and water is disclosed (see Patent Document 3).

  Moreover, the anticorrosion method characterized by apply | coating to the metal raw material which has a rough surface using the cationic electrodeposition coating material containing a silica fine particle, baking after anhydrous washing or water washing is disclosed (refer patent document 4). The electrodeposition paints listed in Patent Document 3 and Patent Document 4 are insufficient for the corrosion resistance required for automobile parts and the like.

JP-A-62-87282 Japanese Patent Laid-Open No. 10-147734 JP 2000-186235 A JP 2005-272952 A

  The object of the present invention is to provide coating performance such as corrosion resistance, weather resistance, impact resistance, finish, and low temperature curability without using harmful metals such as lead compounds and chromium compounds, as well as secondary sagging and cracking. It is to provide an anionic electrodeposition coating composition capable of forming a coating film excellent in coating workability such as property.

  As a result of intensive studies, the present inventors have been subjected to calcium ion exchange with at least one crosslinking agent (B) selected from the group consisting of a specific carboxyl group-containing acrylic resin (A), a melamine resin and a blocked isocyanate compound. It has been found that the above object can be achieved by the anion electrodeposition coating composition containing the amorphous silica fine particles (C), and the present invention has been completed.

  According to the present invention, coating properties such as corrosion resistance, weather resistance, impact resistance, finish, and low temperature curability and secondary sagging / wrinkle properties can be obtained without using harmful compounds such as lead compounds and chromium compounds. It is possible to provide an anionic electrodeposition coating composition having excellent coating workability.

  In particular, with regard to the improvement of secondary sagging / peeling property, the balance of hydrophilicity / hydrophobicity of the electrodeposited coating before baking coating drying can be adjusted in the product of the present invention. Since it is excellent in performance, it is possible to simplify the water washing process in a painting facility (for example, an automobile parts line), and the process can be shortened and an energy saving effect can be obtained.

  Specifically, the anionic electrodeposition coating using a carboxy group-containing acrylic resin obtained by radical polymerization reaction of a mixture containing a specific radical polymerizable unsaturated monomer (a) is curable and anticorrosive. , Weather resistance and excellent. Furthermore, the carboxy group-containing acrylic resin obtained by radical polymerization reaction of the mixture containing the carbonyl group-containing radical polymerizable unsaturated monomer (d) obtains a coating film excellent in adhesion and impact resistance. be able to.

  Furthermore, by containing the amorphous silica fine particles (C) having been subjected to calcium ion exchange, calcium ions eluted from the amorphous silica fine particles (C) having been subjected to calcium ion exchange in a corrosive environment, Since the precipitate was deposited at the interface and the interface between the coating film and the steel sheet was made an alkaline atmosphere, the corrosion resistance was further improved.

  The anion electrodeposition coating composition of the present invention comprises 5 to 95 parts by mass of a specific carboxyl group-containing acrylic resin (A), at least one crosslinking agent (B) 5 selected from the group consisting of a melamine resin and a blocked isocyanate compound. 50 parts by mass, 0.1 to 30 parts by mass of calcium ion-exchanged amorphous silica fine particles (C) with respect to 100 parts by mass in total of the solid content of the carboxyl group-containing acrylic resin (A) and the crosslinking agent (B) An anionic electrodeposition coating composition. Details will be described below.

Carboxyl group-containing acrylic resin (A):
The carboxyl group-containing acrylic resin (A) is a radical polymerizable unsaturated monomer (a) represented by the formula (1) (hereinafter sometimes referred to as “radical polymerizable monomer (a)”). 3-30 mass%, hydroxyl group-containing radical polymerizable unsaturated monomer (b) 10-35 mass%, carboxyl group-containing radical polymerizable unsaturated monomer (c) 1-20 mass%, other radical polymerization It is a resin obtained by subjecting a mixture of 40 to 80% by mass of a polymerizable unsaturated monomer to a radical polymerization reaction.

Formula (1)
(In formula (1), R represents a hydrogen atom or CH ₃ , and R ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms).

Radical polymerizable unsaturated monomer (a):
The radical polymerizable unsaturated monomer (a) is, for example, N-methylolacrylamide, N-methoxymethyl (meth) acrylamide, N-propoxymethyl (meth) acrylamide, Ni-propoxymethyl (meth) acrylamide, N -Butoxymethyl (meth) acrylamide, Ni-butoxymethyl (meth) acrylamide, etc. are mentioned. These radically polymerizable unsaturated monomers (a) can be used alone or in combination of two or more.

Hydroxyl-containing radically polymerizable unsaturated monomer (b):
The hydroxyl group-containing radical polymerizable unsaturated monomer (b) is, for example, acrylic acid or methacrylic acid such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, etc. hydroxyalkyl (meth) acrylates of C ₂ -C _8, (poly) ethylene glycol - mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polybutylene glycol mono (meth) acrylate; these hydroxyl group-containing radical Polymerizable unsaturated monomer and β-propiolactone, dimethylpropiolactone, butyrolactone, γ-valerolactone, γ-caprolactone, γ-caprolactone, γ-laurolactone, ε-caprolactone, δ-caprolactone, etc. Lactone formation As the product name of the reaction product with the product, etc., Plaxel FM1 (manufactured by Daicel Chemical Industries, trade name, caprolactone-modified (meth) acrylic acid hydroxyesters), Plaxel FM2 (same as left), Plaxel FM3 (same as left), Plaxel FA 1 (same as left), Plaxel FA-2 (same as left), Plaxel FA-3 (same as left), and the like. These hydroxyl group-containing radically polymerizable unsaturated monomers (b) can be used alone or in combination of two or more.

Carboxyl group-containing radical polymerizable unsaturated monomer (c):
For example, monomers such as (meth) acrylic acid, maleic acid, crotonic acid, itaconic acid, fumaric acid and the like can be mentioned. These carboxyl group-containing radically polymerizable unsaturated monomers (c) can be used alone or in combination of two or more.

Other radical polymerizable unsaturated monomers:
Other radical polymerizable unsaturated monomers can be appropriately selected and used according to the required performance. For example, styrene, vinyltoluene, 2-methylstyrene, t-butylstyrene, chlorostyrene. Aromatic vinyl monomers such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-, i- or t-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, N-octyl acrylate, decyl acrylate, lauryl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-, i- or t-butyl methacrylate, methacrylic acid Hexyl, 2-ethylhexyl methacrylate, meta C1-C18 alkyl ester or cycloalkyl ester of acrylic acid or methacrylic acid such as octyl rillate, decyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate; glycidyl group containing glycidyl (meth) acrylate, allyl glycidyl ether, etc. Polymerizable monomers; vinyl alkyl ketones having 4 to 7 carbon atoms, such as vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone; carbonyl group-containing radical polymerizable unsaturated monomer (d), acrolein, Examples include diacetone acrylamide, diacetone methacrylamide, formylstyrene, acetoacetoxyethyl (meth) acrylate, acetoacetoxyallyl ester, and the like.

  Here, as the carboxyl group-containing acrylic resin (A), the radical polymerizable unsaturated monomer (a) represented by the formula (1), the hydroxyl group-containing radical polymerizable unsaturated monomer (b), a carboxyl group A carbonyl group-containing radical as a part of the other radical polymerizable unsaturated monomer based on the total mass of the containing radical polymerizable unsaturated monomer (c) and the other radical polymerizable unsaturated monomer A carboxyl group-containing acrylic resin (A) obtained by radical polymerization reaction of a mixture containing 1 to 30% by mass of the polymerizable unsaturated monomer (d) can also be used.

  In particular, by using a carboxyl group-containing acrylic resin (A) obtained by radical polymerization reaction of a mixture containing a carbonyl group-containing radically polymerizable unsaturated monomer (d), adhesion to a substrate, Impact is further improved.

  Production of the carboxyl group-containing acrylic resin (A) using the above-mentioned radical polymerizable unsaturated monomer (A), radical polymerizable monomer (a), hydroxyl group containing radical polymerizable unsaturated monomer (b), Carboxyl group-containing radically polymerizable unsaturated monomer (c) and other radically polymerizable unsaturated monomer are further mixed, and in an organic solvent in the presence of an inert gas such as nitrogen, about 50 ° C. to It can be obtained by radical polymerization reaction at about 300 ° C., preferably about 60 ° C. to 250 ° C., with appropriate addition of a polymerization initiator, for about 1 hour to about 24 hours, preferably about 2 hours to about 10 hours.

  Examples of the organic solvent include alcohols such as n-propanol, isopropanol, n-butanol, t-butyl alcohol, and isobutyl alcohol, ethylene glycol monobutyl ether, methyl carbitol, ethylene glycol monobutyl ether, and 1-methoxy-2. Ether alcohols such as -propanol, 1-ethoxy-2-propanol, propylene glycol monomethyl ether; aromatics such as xylene and toluene; acetone, methyl ethyl ketone, 2-pentanone, 2-hexanone, methyl isobutyl ketone, isophorone, Ketones such as cyclohexanone, methyl acetate, ethyl acetate, pentyl acetate, 3-methoxybutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate Methyl propionate, and ethyl propionate; and the like can be used.

  Examples of the polymerization initiator include benzoyl peroxide, di-t-butyl hydroperoxide, t-butyl hydroperoxide, cumyl peroxide, cumene hydroperoxide, t-butyl peroxybenzoate, lauryl peroxide, and acetyl. Examples include peroxide, azobisdimethylvaleronitrile, azobisisobutyronitrile, and the like.

  The thus obtained carboxyl group-containing acrylic resin (A) has a weight average molecular weight (Note 1) of 3,000 to 60,000, preferably 5,000 to 50,000, and an acid value of 10 to 140 mgKOH. / G, preferably in the range of 30-120 mgKOH, hydroxyl value in the range of 20-170 mgKOH / g, preferably in the range of 30-160 mgKOH / g, corrosion resistance, weather resistance, impact resistance, finish, low temperature curability and secondary It is also suitable for satisfying sagging and sagging properties.

(Note 1) Weight average molecular weight: Measured according to JIS K 0124-83, using TSK GEL4000H _XL + G3000H _XL + G2500H _XL + G2000H _XL (manufactured by Tosoh Corporation) as a separation column at a flow rate of 1.0 ml. / Min, using GPC tetrahydrofuran as the eluent, and calculated from the chromatogram obtained with the RI refractometer and the polystyrene calibration curve.

Crosslinking agent (B):
The crosslinking agent (B) used in the anion electrodeposition coating composition of the present invention comprises a melamine resin and / or a blocked polyisocyanate compound that reacts with the hydroxyl group of the carboxyl group-containing resin (A) from the viewpoint of coating film performance and the like. It is preferable to use it.

  Examples of the melamine resin include a methylolated melamine resin obtained by methylolating melamine with formaldehyde; an alkylated melamine resin obtained by etherifying the methylol group with a monoalcohol; a methylolated melamine resin having an imino group or an alkylated melamine resin. Can do. Further, in the etherification of the methylol group, those obtained by mixed alkylation using two or more monoalcohols can also be used.

  Examples of the monoalcohol include methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, t-butyl alcohol, 2-ethylbutanol, and 2-ethylhexanol. It is done. Specific examples of the melamine resin include methylated melamine resins, imino group-containing methylated melamine resins, methylated / butylated melamine resins, imino group-containing methylated / butylated melamine resins, and the like. Melamine resins and methylated / butylated melamine resins are preferred.

  Examples of commercially available melamine resins include “Cymel 202”, “Cymel 232”, “Cymel 235”, “Cymel 236”, “Cymel 238”, “Cymel 254”, “Cymel 266”, “Cymel 267”, “Cymel 272”, “Cymel 285”, “Cymel 301”, “Cymel 303”, “Cymel 325”, “Cymel 327”, “Cymel 350”, “Cymel 370”, “Cymel 701”, “Cymel 703”, “Cymel 736”, “Cymel 738”, “Cymel 771”, “Cymel 1141”, “Cymel 1156”, “Cymel 1158”, etc. (above, trade name, manufactured by Nippon Cytec Co., Ltd.), “Uban 120”, “Uban 20HS ”,“ Uban 2021 ”,“ Uban 2028 ”,“ Uban 206 "Such as (or more, manufactured by Mitsui Chemicals, Inc., trade name)," Melan 522 ", etc. (manufactured by Hitachi Chemical Co., Ltd., trade name) and the like.

  The blocked polyisocyanate compound is obtained by partially or completely blocking the isocyanate group in the polyisocyanate compound with a blocking agent, and as the polyisocyanate compound, one known per se can be used. , Tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,4′-diisocyanate, diphenylmethane-4,4′-diisocyanate (commonly referred to as “MDI”), crude MDI, bis (isocyanatomethyl) cyclohexane, tetra Aromatic, aliphatic or alicyclic polyisocyanate compounds such as methylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate; cyclization weight of these polyisocyanate compounds Body, isocyanate biuret body; terminal isocyanate-containing compound obtained by reacting an excess amount of these polyisocyanate compounds with low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, trimethylolpropane, hexanetriol, castor oil And so on. These can be used alone or in combination of two or more.

  On the other hand, the blocking agent is added and blocked 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 can be dissociated to regenerate free isocyanate groups.

  Examples of the blocking agent that satisfies such requirements include lactam compounds such as ε-caprolactam and γ-butyrolactam; oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenols such as phenol, para-t-butylphenol, and cresol. Compounds; aliphatic alcohols such as n-butanol and 2-ethylhexanol; aromatic alkyl alcohols such as phenyl carbinol and methyl phenyl carbinol; ether alcohol compounds such as ethylene glycol monobutyl ether and diethylene glycol monoethyl ether Can be mentioned.

  The mixing ratio of the carboxyl group-containing polyester resin (A) and the crosslinking agent (B) can be appropriately changed according to the required coating film performance, but the carboxyl group-containing polyester resin and the crosslinking agent (B). The carboxyl group-containing polyester resin (A) is 50 to 95% by mass, preferably 60 to 90% by mass, more preferably 65 to 85% by mass, and the crosslinking agent (B) 50 based on the total solid content. -5 mass% Preferably it is 40-10 mass%, More preferably, it can be in the range of 35-15 mass%.

Calcium ion exchanged amorphous silica fine particles (C):
The anion electrodeposition coating composition of the present invention contains calcium ion-exchanged amorphous silica fine particles (C) (hereinafter sometimes abbreviated as “ion-exchange silica (C)”). The ion exchange silica (C) is silica fine particles in which calcium ions are introduced into a fine porous silica carrier by ion exchange.
It is considered that the ion exchange silica (C) blended in the coating film is ion-exchanged with hydrogen ions or the like that have permeated through the coating film, and calcium ions Ca ²⁺ are released to protect the metal surface. When ion-exchanged silica (C) is blended in an anionic electrodeposition coating, a further anticorrosion property can be obtained by electrodeposition coating, compared to a coating in which a conventionally known aqueous coating is applied to spray coating or brush coating. .

Examples of such commercially available ion-exchange silica include SHIELDEX (Shielddex, registered trademark) C303, SHIELDEX AC-3, SHIELDEX AC-5 (all of which are manufactured by WR Grace & Co.). be able to.
In this invention, the compounding quantity of ion exchange silica (C) is 0.1-30 mass parts with respect to a total of 100 mass parts of carboxyl group-containing polyester resin (A) and a crosslinking agent (B), Preferably it is 0. Within the range of 5 to 25 parts by mass, more preferably 1 to 20 parts by mass.

  In addition to the ion exchange silica (C), the anion electrodeposition coating composition includes, for example, coloring pigments such as titanium white and carbon black, extender pigments such as clay, talc, and barita, tripolyphosphoric acid. A ball mill, a sand mill, a sand mill and a disulfuric acid, phosphomolybdic acid, bismuth oxide, bismuth hydroxide, basic bismuth carbonate, bismuth carbonate, bismuth nitrate, bismuth silicate, etc. It is preferable to use a pigment dispersion paste obtained by dispersing the pigment using a dispersing means such as a shaker from the viewpoints of corrosion resistance, finish, and paint stability. Further, it is preferable to use a combination of two kinds of antirust components such as ion exchange silica (C) and bismuth hydroxide, or ion exchange silica (C) and aluminum dihydrogen phosphate, in order to improve corrosion resistance. .

Epoxy resin (D):
The anion electrodeposition coating composition of the present invention can be blended with an epoxy resin (D) for the purpose of improving corrosion resistance. The epoxy resin (D) is obtained by reacting an epoxy group of an epoxy resin (d1) having an epoxy equivalent of 180 to 10,000 having at least one epoxy group in one molecule obtained by reaction of a polyphenol compound and epichlorohydrin with active hydrogen. Examples thereof include an epoxy resin blocked with the containing compound (e) (hereinafter referred to as an epoxy resin (D1)).

  Examples of the polyphenol compound used for the production of the epoxy resin (d1) include 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 novolak, cresol novolak, and the like. it can.

  As an epoxy resin obtained by the reaction between a polyphenol compound and epichlorohydrin, among others, the following formula (2) derived from bisphenol A:

  Formula (2) What is shown by n = 0-8 is suitable.

Examples of such a commercially available epoxy resin (d1) include those sold by Japan Epoxy Resins Co., Ltd. under trade names such as Epicoat 828EL, 1002 on the left, 1004 on the left, and 1007 on the left.
The epoxy resin (d1) has a number average molecular weight in the range of 400 to 20,000, preferably 800 to 15,000 (see Note 1), 180 to 15,000, preferably in the range of 300 to 10,000. It is preferable to have an epoxy equivalent of

  As the active hydrogen-containing compound (d2) to be reacted with the epoxy group of the epoxy resin (d1), a compound having a phenol group or a carboxyl group is suitable. In addition, the active hydrogen-containing group may be at least one per molecule, but monophenols, aliphatic monocarboxylic acids, aromatic monocarboxylic acids, etc. may be used from the viewpoint of ease of reaction and storage stability of the resin emulsion. Is preferred. Specific examples of the monophenols include phenol, cresol, ethylphenol, para-tert-butylphenol, nonylphenol and the like.

  Examples of the aliphatic carboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, acrylic acid, lactic acid, dimethylolpropionic acid, and dimethylolbutyric acid. Examples of the aromatic carboxylic acids include benzoic acid and gallic acid.

The ratio of the epoxy group of the epoxy resin (d1) to the active hydrogen group of the active hydrogen-containing compound (e) is 1.5 to 0.75 mol, preferably 1.2 to 0.00. 8 moles. In addition, since the epoxy group of the epoxy resin (D1) is blocked by the active hydrogen-containing compound (e), the coating stability is excellent.
Moreover, as an epoxy resin (D), following formula (3) is added to an epoxy resin (d1).

Formula (3)
(In the formula, R represents a hydrogen atom or CH ₃ , and n represents 2 to 6)
An epoxy resin (d12) modified by cyclic ester compound (d12) represented by the following formula is used, and the epoxy group of the epoxy resin (d12) is blocked with an active hydrogen-containing compound (e) (D12) ) Can also be used.
As the active hydrogen-containing compound (e), the same active hydrogen-containing compound as that used for the production of the epoxy resin (D1) can be used.

  Specific examples of the cyclic ester compound (d2) include δ-valerolactone, γ-valerolactone, ζ-enalactone, ε-enalactone, δ-caprolactone, ε-caprolactone, η-caprolactone, ζ- Examples include caprylolactone, and ε-caprolactone is particularly preferable.

  The reaction between the epoxy resin (d1) and the cyclic ester compound (d2) can be carried out by a method known per se. For example, as a catalyst, a titanium compound such as tetrabutoxy titanium or tetrapropoxy titanium; tin octylate, dibutyltin Organotin compounds such as oxide and dibutyltin laurate; a hydroxyl group-containing epoxy resin and a cyclic ester compound in the presence of a metal compound such as stannous chloride at a temperature of about 100 ° C. to about 250 ° C. for about 1 to about 15 hours. This is done by heating. The said catalyst can be normally used within the range of 0.5-1,000 ppm based on the total amount of a hydroxyl-containing epoxy resin and a cyclic ester compound.

  The amount of the cyclic ester compound used is not strictly limited, but generally, the component derived from the cyclic ester compound (d2) is 5 to 5 in the produced cyclic ester compound-modified epoxy resin (d12). It is preferable to adjust so as to occupy 40% by mass, preferably 10 to 35% by mass.

  The epoxy resin (D) is a modified epoxy resin (d13) obtained by reacting the polyglycidyl ether of the polyhydric polyol (d3) with the epoxy resin (d1), and the epoxy group of the modified epoxy resin (d13) is changed. An epoxy resin (D13) blocked with an active hydrogen-containing compound (e) can also be used. The epoxy resin (d1) and the active hydrogen-containing compound (e) are the same as the active hydrogen-containing compound. Examples of the polyvalent polyol (d3) include polyethylene polyol, polypropylene polyol, and polycaprolactone polyol.

Although an epoxy resin (D) can be used even if it does not contain a carboxyl group, it can also be used as a carboxyl group-containing epoxy resin (D2) containing a carboxyl group. As the epoxy resin (D), it is preferable to use a carboxyl group-containing epoxy resin (D2) from the viewpoint of coating stability.
In addition, the introduction of a carboxyl group into the epoxy resin (D) is, for example, a half esterification reaction at a temperature of 100 to 180 ° C. with a polybasic acid anhydride being part of the hydroxyl group of the epoxy resin (D1). It can be done by adding.
The carboxyl group-containing epoxy resin (D2) has an acid value of 0.1 to 100 mgKOH / g, preferably 0.5 to 80 mgKOH / g, and more preferably 2 to 80 mgKOH / g.

  In addition, as a compounding quantity of the epoxy resin (D) in the anion electrodeposition coating composition of this invention, with respect to the total solid content of a carboxyl group-containing polyester resin (A), a crosslinking agent (B), and an epoxy resin (D), The epoxy resin (D) is preferably contained in an amount of 0.1 to 45% by mass, preferably 1 to 42% by mass, and more preferably 5 to 40% by mass from the viewpoints of corrosion resistance, weather resistance and paint stability.

Resol type phenol resin (E):
Furthermore, the anionic electrodeposition coating composition of the present invention suitably contains a resol type phenol resin (E) with respect to 100 parts by mass of the resin component excluding the resol type phenol resin (E) for the purpose of improving corrosion resistance. 0.1-40 mass parts, Preferably it is 0.5-30 mass parts, More preferably, it can contain 1-20 mass parts.

The resol type phenol resin (E) serves as an auxiliary agent for crosslinking between the carboxyl group-containing polyester resin (A) and the crosslinking agent (B), and phenols such as phenol and bisphenol A and aldehydes such as formaldehyde A phenol resin in which a methylol group is introduced by a condensation reaction in the presence of a reaction catalyst, and a part of the introduced methylol group alkylated with an alcohol having 6 or less carbon atoms are also included.
The resol type phenol resin (E) has a number average molecular weight (Note 1) in the range of 100 to 3,000, preferably 150 to 2,000, and may be etherified per benzene nucleus. It is appropriate that the average number of methylol groups is in the range of 0.3 to 3.0, preferably 0.5 to 3.0, and more preferably 0.7 to 3.0.

  By using the above-mentioned resol type phenol resin (E) in the anionic electrodeposition coating material of the present invention, a coating film having excellent coating performance such as corrosion resistance and impact resistance can be formed.

[Anion electrodeposition coating composition]
The anion electrodeposition coating composition of the present invention comprises a carboxyl group-containing acrylic resin (A) and a crosslinking agent (B), and if necessary, an epoxy resin (D), a resol type phenol resin (E), a surfactant, a surface After blending a regulator and an antifoaming agent, etc., and thoroughly mixing them, in a normal aqueous medium, neutralizing with a basic compound to make the carboxyl group-containing acrylic resin (A) water-soluble or water-dispersed, Resin emulsions can be prepared. Moreover, according to the objective, resin emulsions, such as a polyester resin emulsion and a urethane resin emulsion, can also be mix | blended.

  Examples of basic compounds that can be used for the neutralization include hydroxides of alkali metals or alkaline earth metals such as sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, and barium hydroxide; ammonia Primary amines such as ethylamine, propylamine, butylamine, benzylamine, monoethanolamine, neopentanolamine, 2-aminopropanol, 3-aminopropanol; diethylamine, diethanolamine, di-n- or di-i-propanol Secondary monoamines such as amine, N-methylethanolamine, N-ethylethanolamine; dimethylethanolamine, trimethylamine, triethylamine, triisopropylamine, methyldiethanolamine, dimethylaminoethanol, etc. Mention may be made of any tertiary monoamine; polyamines such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine. These basic compounds are usually in the range of 0.1 to 1 equivalent, preferably 0.3 to 0.9 equivalent, relative to the carboxyl group of the carboxyl group-containing polyester resin (A) from the viewpoint of coating stability and the like. Are preferably used.

  Furthermore, in order to accelerate the crosslinking reaction of the coating film, a sulfonic acid compound can be added. Examples of the sulfonic acid compounds include n-butylbenzenesulfonic acid, n-amylbenzenesulfonic acid, n-octylbenzenesulfonic acid, n-dodecylbenzenesulfonic acid, n-octadecylbenzenesulfonic acid, and n-dibutylbenzenesulfonic acid. I-propyl naphthalene sulfonic acid, dodecyl naphthalene sulfonic acid, dinonyl naphthalene sulfonic acid, dinonyl naphthalene disulfonic acid, and the like, and neutralized amines of these sulfonic acids, among others, exhibit particularly excellent effects. It is preferable to use an amine neutralized product of dinonylnaphthalenesulfone.

  The content of these sulfonic acid compounds in the anion electrodeposition coating composition of the present invention is not strictly defined and can be varied over a wide range depending on the performance required for the coating, etc. The amount is preferably 10 parts by mass or less, preferably in the range of 0 to 5.0 parts by mass, per 100 parts by mass of the total solid content of the carboxy group-containing polyester resin (A) and the crosslinking agent (B).

In addition, the anion electrodeposition coating material using the anion electrodeposition coating composition of this invention mixes the said resin emulsion and the pigment dispersion paste containing a silica fine particle (C), and solid content is 5-40 with deionized water. % By mass, preferably 8 to 25% by mass, pH adjusted to within the range of 7 to 10, and electrodeposition is usually performed with the substrate to be coated as an anode under conditions of a bath temperature of 10 to 35 ° C. and a load voltage of 100 to 400 V. By coating, it can be applied to the surface of the desired conductive substrate The film thickness of the electrodeposition coating film formed by electrodeposition coating is not particularly limited, Based on the range of 10 to 40 μm, particularly 15 to 35 μm is preferable. Further, the baking temperature of the coating film is generally about 120 to about 200 ° C., preferably about 130 to about 170 ° C. on the surface of the object to be coated, and the baking time is about 5 to 60 minutes, preferably 10 It can be about 30 minutes.

  The anion electrodeposition paint of the present invention is suitably used as an electrodeposition paint application, but is not limited to electrodeposition paint, and is used for anticorrosion for coating by water or other methods such as electrostatic paint, spray paint, roll paint, etc. It can also be used as a primer.

EXAMPLES Next, although an Example is hung up and this invention is demonstrated further more concretely, this invention is not limited only to these Examples. In the examples and comparative examples, “parts” and “%” mean “parts by mass” and “% by mass” unless otherwise specified.
Production Example 1 Production of Carboxyl Group-Containing Acrylic Resin (A) Solution Into a flask equipped with a stirrer, thermometer, nitrogen inlet tube and reflux condenser, 290 parts of propylene glycol monomethyl ether was charged and kept at 120 ° C. The following “mixture” was added dropwise over 3 hours, then 3 parts of azobisdimethylvaleronitrile was added, and the reaction was carried out while maintaining at 120 ° C. for 1 hour. One solution was obtained. The carboxyl group-containing acrylic resin had an acid value of 78 mgKOH / g, a hydroxyl value of 145 mgKOH / g, and a weight average molecular weight of 16,000.
"blend"
Styrene 60 parts n-butyl acrylate 240 parts Nn-butoxymethylacrylamide 60 parts 2-hydroxyethyl acrylate 180 parts acrylic acid 60 parts azobisisobutyronitrile 36 parts.

Production Examples 2-3, Comparative Production Examples 1-2
In Production Example 1, a carboxyl group-containing acrylic resin No. 65 having a resin solid content of 65% was prepared in the same manner except that the content of “mixture” in Table 1 was used. 2-No. Five solutions were obtained. In addition, carboxyl group-containing acrylic resin no. 2-No. 5 shows the acid value, hydroxyl value, and number average molecular weight.

Production Example 4 Production of Epoxy Resin (D) Epicoat 828EL (trade name, epoxy resin, epoxy equivalent 190, molecular weight 350, manufactured by Japan Epoxy Resin Co., Ltd.) was attached to a flask equipped with a stirrer, thermometer, nitrogen inlet tube and reflux condenser. To 500 parts, 200 parts of bisphenol A and 0.1 part of dimethylbenzylamine were added and reacted at 130 ° C. until an epoxy equivalent of 750 was reached. Thereto, 135 parts of dimethylol butyric acid and 210 parts of ethylene glycol monobutyl ether were added and reacted at 130 ° C. for 4 hours to obtain an epoxy resin solution No. 80 having a resin solid content of 80%. 1 was obtained.

Production Example 5 Production of carboxyl group-containing epoxy resin solution To a flask equipped with a stirrer, thermometer, nitrogen introduction tube and reflux condenser, Epicoat 828EL (trade name, epoxy resin, epoxy equivalent 190, molecular weight 350, manufactured by Japan Epoxy Resin Co., Ltd.) ) To 500 parts, 200 parts of bisphenol A and 0.1 part of dimethylbenzylamine were added and reacted at 130 ° C. until an epoxy equivalent of 750 was reached. Thereto, 135 parts of dimethylol butyric acid was added and reacted at 130 ° C. for 4 hours. Subsequently, 77 parts of trimellitic anhydride was added, followed by heating at 130 ° C. for 1 hour, addition of 228 parts of ethylene glycol monobutyl ether, and a carboxy group-containing epoxy resin solution No. 80 having a resin solid content of 80%. 2 was obtained. The carboxy group-containing epoxy resin No. 2 had an acid value of 50 mgKOH / g.

Production Example 6 Production of Block Polyisocyanate Curing Agent In a flask equipped with a stirrer, thermometer, nitrogen inlet tube and reflux condenser, methyl isobutyl ketone 44 parts was added to 222 parts of isophorone diisocyanate, and the temperature was raised to 70 ° C. Thereafter, 174 parts of methyl ethyl ketoxime was added dropwise over 2 hours, and sampling was performed over time while maintaining this temperature, and it was confirmed by infrared absorption spectrum measurement that there was no absorption of unreacted isocyanate. % Block polyisocyanate curing agent was obtained.

Production Example 7 Emulsion No. Production of carboxy group-containing acrylic resin solution No. 1 having a resin solid content of 57% obtained in Production Example 1 above. 1 to 107.7 parts (solid content 70 parts), Nicalak MX-430 (Note 2) 30 parts (solid content 30 parts), triethylamine 19 parts (0.25 equivalents) and deionized water 155.8 parts. In addition, it was water-dispersed and emulsion No. 32 having a solid content of 32% 1 was obtained.
(Note 2) Nicalac MX-430: Sanwa Chemical Co., Ltd., trade name, melamine resin, solid content 100%.

Production Examples 8-20
In the same manner as in Production Example 7, emulsion Nos. 2-No. 14 was obtained. Table 2 shows the contents of the formulation.

(Note 3) Shounol CKS394: trade name, manufactured by Showa Polymer Co., Ltd., resol type phenol resin.

Production Example 21 Acrylic Resin Solution for Dispersing Pigment In an ordinary acrylic resin reaction vessel equipped with a stirrer, a thermometer and a reflux condenser, 37 parts of ethylene glycol monobutyl ether was charged and stirred at a temperature of 110 ° C. Among them, 10 parts of styrene, 35 parts of methyl methacrylate, 20 parts of 2-ethylhexyl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, 40 parts of NF biisomer S20W (Note 4), 1 part of azobisisobutyronitrile and 5 parts of isobutyl alcohol The mixture consisting of was added dropwise over 3 hours.
After completion of the dropwise addition, the mixture was aged at 110 ° C. for 30 minutes, and then an additional catalyst mixture composed of 20 parts of ethylene glycol monobutyl ether and 0.5 part of azobisisobutyronitrile was added dropwise over 1 hour. Next, the mixture was aged at 110 ° C. for 1 hour and then cooled to obtain an acrylic resin solution for pigment dispersion having a resin solid content of 55%.
(Note 4) NF biisomer S20W: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name, 50% water-diluted product of methoxypolyethylene glycol monomethacrylate, molecular weight of about 2,080.

Production Example 22 Pigment Dispersion Paste No. Production of 1 5.5 parts (3 parts solids) acrylic resin solution for pigment dispersion having a solid content of 55% obtained in Production Example 21, 3 parts carbon MA-7 (Note 5), hydride PXN (Note 6) 7 parts, 2 parts of Shieldex C303 (Note 7) and 9.8 parts of deionized water were dispersed in a ball mill for 20 hours to obtain a pigment dispersion paste No. 1 was obtained.

Production Examples 23 to 28 Pigment dispersion paste No. 2-No. Production of Pigment Dispersion Paste No. 7 in Production Example 22 In the same manner as in No. 1, pigment dispersion paste No. 1 2-No. 7 was obtained. Table 3 shows the details of the formulation.

(Note 5) Carbon MA-7: Mitsubishi Kasei Co., Ltd., trade name, carbon black (Note 6) Hydride PXN: Georgia Kaolin, trade name, aluminum silicate (Note 7) Shielddex C303: W. R. Grace & Co. Product name, calcium ion exchanged amorphous silica fine particles, calcium component 3%
(Note 8) Shieldex AC-3: R. Grace & Co. Product name, calcium ion exchanged amorphous silica fine particles, calcium component 3%
(Note 9) Shieldex AC-5: R. Grace & Co. Product name, calcium ion exchanged amorphous silica fine particles, calcium component 3%
(Note 10) KW-840E: manufactured by Teica, trade name, aluminum dihydrogen tripolyphosphate.

Examples and Comparative Examples Example 1
Emulsion No. obtained in Production Example 7 1 to 312.5 parts (solid content: 100), the pigment dispersion paste No. 1 obtained in Production Example 24 was used. No. 1 was added with 27.3 parts (solid content 15 parts) and deionized water 235.2 parts. 1 was obtained.

Examples 2-12
In the same manner as in Example 1, the anionic electrodeposition paint Nos. 2-No. 12 was obtained.

Comparative Examples 1-13
In the same manner as in Example 1, the anionic electrodeposition paint Nos. 13-No. 25 was obtained.

Comparative Example 14
As Comparative Example 14, Eleclon # 7100 Black (Note 11) was used.
(Note 11) ELECRON # 7100 Black: An anionic electrodeposition paint using an unsaturated resin obtained by reacting maleic anhydride with a polybutadiene / epoxy resin fatty acid ester / linseed oil mixture, manufactured by Kansai Paint Co., Ltd.

Coating test Cold rolled steel sheet (0.8 mm x 150 mm) formed by chemical conversion treatment with Palbond # 3020 (manufactured by Nippon Parkerizing Co., Ltd., trade name, zinc phosphate treating agent) in each anion electrodeposition paint obtained in the above Examples and Comparative Examples X70 mm) was immersed, electrodeposition coating was performed at a voltage and energization time so that a dry film thickness of 20 μm was obtained with the object to be coated as an anode, and a test plate was obtained by baking at 130 ° C. for 20 minutes. . Tables 6 and 7 show the results of performance tests using the obtained test plates. The performance test was performed according to the following method.

(Note 12) Anticorrosion:
The electrodeposited coating on each test plate was cross-cut with a knife so as to reach the substrate, and this was subjected to a salt spray resistance test for 840 hours according to JISZ-2371. Evaluation based on the criteria.
◎ indicates that the maximum width of rust and blisters is less than 2 mm from the cut part (one side)
○, the maximum width of rust and blisters is 2mm or more and less than 3mm (one side) from the cut part,
△ indicates that the maximum width of rust and blisters is 3 mm or more and less than 4 mm (one side) from the cut part,
X indicates that the maximum width of rust and blisters is 4 mm or more (one side) from the cut part.

(Note 13) Impact resistance:
After each test plate with a dry film thickness of 20 μm is placed in a constant temperature and humidity chamber at a temperature of 20 ° C. ± 1 and a humidity of 75 ± 2% for 24 hours, a cradle and a striker of the specified size are attached to the DuPont impact tester. The test plate is placed face up and sandwiched between them, and then a weight of 500 g is dropped on the striker (1/2 inch). The thickness (cm) was measured.

(Note 14) Weather resistance:
Each test plate having a dry film thickness of 20 μm conforms to JIS H 8602 5.12 (1992) (water spray time 12 minutes, black panel temperature 60 ° C.), and a sunshine weatherometer, a sunshine carbon arc type accelerated weathering tester The gloss retention (%) (60-degree specular gloss after the test / 60-degree specular gloss before the test) divided by 80% was measured.
◎: Gloss retention rate (%) exceeds 80 hours for less than 400% ○: Gloss retention rate (%) exceeds 80 hours for less than 150 hours and less than 400 hours △: Gloss retention The time when the rate (%) is less than 80% exceeds 50 hours and is less than 150 hours. X: The time when the gloss retention rate (%) is less than 80% is less than 50 hours.

(Note 15) Secondary sagging resistance:
As shown in FIG. 1, two steel plates (1) and a steel plate (2) are rolled up together (the clearance between the steel plate (1) and the steel plate (2) is 100 μm) to produce a jig, and a 20 μm dry coating film is obtained. Electrodeposition coating was performed under the conditions described above, washed with water, set for 10 minutes, and baked at 130 ° C. for 20 minutes to observe the state of secondary sagging and peeling of the coated surface.
◯: Good without secondary sagging / flaking △: Slight secondary sagging / waisting, slightly bad x: Poor secondary sagging / waisting

(Note 16) Finishability:
Electrodeposition coating was carried out under the condition that a dry coating film of 20 μm was obtained, then washed with water, baked and dried at 130 ° C. for 20 minutes, and evaluated for armpit, dent and smoothness.
○ indicates that there is no problem in any of the armpits, dents and smoothness. Δ indicates that any of the armpits, dents and reduced smoothness is observed. × indicates that any of the armpits, dents and reduced smoothness is remarkably observed.

(Note 17) Paint stability:
Each anion electrodeposition coating material was hermetically stirred at 30 ° C. for 1 month, and each anion electrodeposition coating material was filtered through a 400-mesh filter screen to measure the amount of residue (mg / L).
◎: Residue amount less than 5 mg / L ○: Residue amount is 5 mg / L or more and less than 10 mg / L △: Residue amount is 10 mg / L or more and less than 15 mg / L ×: Residue amount Over 15 mg / L.

  If the anion electrodeposition coating material of the present invention is used, a coated article having excellent corrosion resistance, weather resistance, impact resistance, finish, and low-temperature curability can be obtained without using harmful metals.

It is the schematic of the panel for a test | inspection of the secondary sagging property which made the clearance of cold-rolled steel plate (1) and cold-rolled steel plate (2) 100 micrometers.

Explanation of symbols

1. Cold-rolled steel sheet with chemical conversion treatment (1) (0.8 mm x 70 mm x 150 mm)
2. Cold-rolled steel sheet with chemical conversion treatment (2) (0.8 mm x 50 mm x 50 mm)
3. After the test, the paint sagging water that exudes is shown.

Claims (7)

50 to 95 parts by mass of a carboxyl group-containing acrylic resin (A) having the following characteristics, 5 to 50 parts by mass of a crosslinking agent (B) selected from a melamine resin and a blocked isocyanate compound, a carboxyl group-containing acrylic resin (A Anionic electrodeposition coating composition containing 0.1 to 30 parts by mass of calcium ion-exchanged amorphous silica fine particles (C) with respect to 100 parts by mass of the total solid content of the crosslinking agent (B).
Carboxyl group-containing acrylic resin (A):
3 to 30% by mass of the radical polymerizable unsaturated monomer (a) represented by the formula (1), 10 to 35% by mass of the hydroxyl group-containing radical polymerizable unsaturated monomer (b), and carboxyl group-containing radical polymerization It is a resin obtained by radical polymerization reaction of a mixture of 1 to 20% by mass of the unsaturated unsaturated monomer (c) and 40 to 80% by mass of the other radical polymerizable unsaturated monomer.

Formula (1)
(In the formula (1), R represents a hydrogen atom or CH ₃ , and R ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms) The carboxyl group-containing acrylic resin (A) is a radical polymerizable unsaturated monomer (a) represented by the formula (1), a hydroxyl group-containing radical polymerizable unsaturated monomer (b), a carboxyl group-containing radical polymerizable property. Based on the total mass of unsaturated monomer (c) and other radical polymerizable unsaturated monomer, carbonyl group-containing radical polymerizable unsaturated monomer as part of other radical polymerizable unsaturated monomer. The anion electrodeposition coating composition according to claim 1, comprising 1 to 30% by mass of the monomer (d). The anion electrodeposition coating composition according to claim 1 or 2, wherein the carboxyl group-containing acrylic resin (A) has an acid value of 10 to 140 mgKOH / g. An epoxy resin (D) obtained by blocking an epoxy group of an epoxy resin (d1) having an epoxy equivalent of 180 to 10,000 with an active hydrogen-containing compound (e) is converted into a carboxyl group-containing acrylic resin (A), a crosslinking agent (B), and an epoxy. The anion electrodeposition coating composition according to any one of claims 1 to 3, which is contained in an amount of 0.1 to 40% by mass relative to the total solid content of the resin (D). The anionic electrodeposition coating composition according to claim 4, wherein the epoxy resin (D) is a carboxyl group-containing epoxy resin having an acid value of 0.1 to 100 mgKOH / g. The anion battery according to any one of claims 1 to 5, comprising 0.1 to 40 parts by mass of the resol type phenol resin (E) with respect to 100 parts by mass of the resin component excluding the resol type phenol resin (E). Coating composition. The coated article formed by electrodeposition-coating the anion electrodeposition coating composition of any one of Claims 1-6.

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