JP2006131695A - Heat-curable aqueous coating and method for forming film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-curable aqueous coating having a wide range of coating workability and capable of forming a film extremely excellent in finish properties, such as smoothness of a surface of the film and a metallic feeling, and to provide a method for forming the film. <P>SOLUTION: This heat-curable aqueous coating comprises an oligomer (A-1) and/or a polyester resin (A-2), a crosslinking agent (B), and water-dispersible polymer particles (C), wherein the oligomer (A-1) is obtained by reacting a compound having three or more carboxyl groups in its molecule with a monoepoxide compound having a long-chain hydrocarbon group and has a specified acid value, hydroxy value, and number-average molecular weight, and the polyester resin (A-2) is obtained by reacting the oligomer (A-1) with a polycarboxylic acid and/or a polycarboxylic anhydride and/or a polyisocyanate compound. The method for forming the film using the coating is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a water-based paint which can form a coating film excellent in finish properties such as metallic feeling and coating surface smoothness, comprising a novel oligomer and / or polyester resin, and a coating film forming method using the water-based paint. .

  In the paint field, reduction of the amount of organic solvent used is an important issue from the viewpoint of environmental conservation and resource saving. In recent years, in order to reduce the amount of organic solvent in the paint, the development of water-based paint and high solid differentiation has been promoted.

  As water-based paints in the field of automotive paints, for example, thermosetting water-based paints containing polyvalent carboxylic acid resin, amino resin, linear low-molecular polyester diol and benzoin as main components are known (for example, see Patent Document 1). However, the solid content concentration is low, and the smoothness of the coating film is not sufficient.

  Among automotive paints, top coats are required to have excellent appearance quality, and when metallic paints are used, the scale-like glitter pigments such as aluminum in the metallic base paints should be well oriented. Therefore, it is required to obtain a coating film appearance excellent in finish properties such as metallic feeling.

  As an aqueous metallic base paint used for such metallic coating, for example, it is possible to maximize the flip-flop effect of the metallic pigment and to have a metallic feeling, characterized in that it contains crosslinked polymer fine particles in the aqueous base paint. A base coat composition that forms an excellent coating film has been proposed (see, for example, Patent Document 2). However, the composition has a defect that coating film defects such as sagging and unevenness are likely to occur due to changes in coating conditions, particularly humidity.

  In addition, in the coating method of 2 coats and 1 bake, for example, as a paint used for aqueous metallic base coating, as a water dispersion containing polymer fine particles, for example, a specific long chain monomer such as stearyl acrylate or stearyl methacrylate is used. A method for forming a coating film using a copolymerized aqueous dispersion has also been proposed (for example, see Patent Document 3), but there are problems such as insufficient coating workability, smoothness, and finished properties such as a metallic feeling. is there.

JP-A-4-93374 Japanese Patent Publication No. 3-14869 JP 2001-104878 A

  An object of the present invention is to provide a thermosetting water-based paint and a method for forming a coating film, which can form a coating film having a wide coating workability range and excellent finish properties such as coating surface smoothness and metallic feeling. is there.

  The present inventors have now developed an oligomer having a specific composition and a polyester resin obtained by further increasing the molecular weight of the oligomer, a thermosetting water-based paint using the oligomer and / or polyester resin, and a coating film using the same. The inventors have found that the above object can be achieved by a forming method, and have completed the present invention.

Thus, the present invention is a paint containing (A) an oligomer (A-1) and / or a polyester resin (A-2), (B) a crosslinking agent and (C) water-dispersible polymer particles,
The component (A-1) is obtained by reacting a compound (a-1) having 3 or more carboxyl groups in one molecule with a monoepoxide compound (a-2) having a long-chain hydrocarbon group 30 An oligomer having a hydroxyl value in the range of ~ 300 mgKOH / g, an acid value in the range of 20-220 mgKOH / g and a number average molecular weight in the range of 300-2000,
The component (A-2) further reacts with the component (A-1) with a polyvalent carboxylic acid and / or a polyvalent carboxylic acid anhydride (a-3) and / or a polyisocyanate compound (a-4). A polyester resin having a hydroxyl value in the range of 10 to 200 mg KOH / g, an acid value in the range of 10 to 100 mg KOH / g, and a number average molecular weight in the range of 400 to 6000, obtained by heating. A curable water-based paint is provided.

  The present invention also provides a method of forming a multilayer coating film using the above thermosetting water-based paint.

  The thermosetting water-based paint of the present invention forms a coating film having an extremely excellent finish, and particularly when used as a water-based metallic base coat paint, it is possible to achieve high solid differentiation of the paint, smoothness, metallic It is possible to obtain a coating film having excellent finish such as feeling. In addition, the thermosetting water-based paint of the present invention has an effect that the appropriate width of the coating work with respect to changes in temperature and humidity is wider than that of the conventional water-based paint.

Hereinafter, the thermosetting water-based paint and coating film forming method of the present invention will be described in more detail.

Thermosetting water-based paint The thermosetting water-based paint (hereinafter referred to as “the present paint”) of the present invention comprises (A) the oligomer (A-1) and / or the polyester resin (A-2), the crosslinking agent (B), and It contains water-dispersible polymer particles (C) as an essential component.

Oligomer (A-1)
The oligomer (A-1) of this paint is obtained by reacting a compound (a-1) having three or more carboxyl groups in one molecule and a monoepoxide compound (a-2) having a long chain hydrocarbon group. It is an oligomer having a hydroxyl value in the range of 30 to 300 mgKOH / g, an acid value in the range of 20 to 220 mgKOH / g, and a number average molecular weight in the range of 300 to 2000.

  The method for synthesizing the oligomer (A-1) is not particularly limited, and can be performed according to an ordinary method. For example, each of the components (a-1) and (a-2) described above in a nitrogen stream, It can be synthesized by heating at about 100 to about 160 ° C. for about 1 to 8 hours and carrying out an esterification reaction between the carboxyl group in component (a-1) and the epoxy group in component (a-2). . At that time, as the catalyst, for example, a quaternary ammonium salt compound such as tetrabutylammonium bromide can be used as necessary.

  The compound having three or more carboxyl groups in one molecule is a tribasic or higher polybasic acid compound. Examples of the component (a-1) include trimellitic acid, pyromellitic acid, and trimesic acid. , Butanetricarboxylic acid, butanetetracarboxylic acid, hexanetricarboxylic acid, methylcyclohexenecarboxylic acid, and the like. In addition, compounds having an acid anhydride group such as trimellitic anhydride and pyromellitic anhydride are also included in the component (a-1). In this case, one acid anhydride group is assumed to be divalent or bifunctional.

  These compounds (a-1) having three or more carboxyl groups in one molecule can be used alone or in combination of two or more.

  The monoepoxide compound (a-2) having a long chain hydrocarbon group is a monoepoxide compound having a chain or cyclic hydrocarbon group having 4 or more carbon atoms, preferably 6 to 20 carbon atoms, and the monoepoxide compound Specific examples of (a-2) include pivalic acid glycidyl ester, hexanoic acid glycidyl ester, cyclohexanecarboxylic acid glycidyl ester, 2-ethylhexanoic acid glycidyl ester, isononanoic acid glycidyl ester, decanoic acid glycidyl ester, and undecane. Acid glycidyl ester, lauric acid glycidyl ester, myristic acid glycidyl ester, palmitic acid glycidyl ester, stearic acid glycidyl ester, Cardura E10P (manufactured by Japan Epoxy Resin, Neodecanoic acid monoglycidyl ester) Any glycidyl ester; glycidyl ethers such as butyl glycidyl ether, phenyl glycidyl ether, decyl glycidyl ether; and α-olefin monoepoxides such as styrene oxide and AOEX24 (a mixture of α-olefin monoepoxides manufactured by Daicel Chemical Industries) .

  The hydrocarbon group having 4 or more carbon atoms may have a substituent such as a hydroxyl group. As the monoepoxide compound having a hydrocarbon group having such a substituent, specifically, for example, 1 , 2-epoxyoctanol, hydroxyoctyl glycidyl ether, and the like.

  Moreover, from the viewpoints of wettability, compatibility, etc., as the component (a-2), it is preferable to use a monoepoxide compound having a hydrocarbon group having 6 to 20 carbon atoms, and in particular, having 6 to 20 carbon atoms. A glycidyl ester compound having a hydrocarbon group is preferred.

  These monoepoxide compounds (a-2) having a long-chain hydrocarbon group can be used alone or in combination of two or more.

  The oligomer (A-1) has a number average molecular weight in the range of 300 to 2000, preferably 400 to 1500, an acid number in the range of 20 to 220 mgKOH / g, preferably 30 to 180 mgKOH / g, and 30 to 300 mgKOH / g. g, preferably having a hydroxyl value in the range of 50 to 200 mg KOH / g. In addition, when a hydroxyl value becomes smaller than 30 mgKOH / g, the tendency for sclerosis | hardenability to become inadequate is seen.

  In addition, in this specification, a number average molecular weight is the value which converted the number average molecular weight measured with the gel permeation chromatograph (The Tosoh company make, "HLC8120GPC") on the basis of the number average molecular weight of polystyrene. Columns are “TSKgel G-4000H × L”, “TSKgel G-3000H × L”, “TSKgel G-2500H × L”, “TSKgel G-2000H × L” (both manufactured by Tosoh Corporation, trade names) ), Mobile phase: tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 cc / min, detector: RI.

  The proportion of the components (a-1) and (a-2) used is selected so that the number average molecular weight, acid value, and hydroxyl value of the resulting oligomer (A-1) are in the above-described ranges.

  The proportion of the components (a-1) and (a-2) used is the ratio of the total number of moles of the component (a-2) to the total number of moles of the component (a-1) (R = (a-2) The total number of moles / the total number of moles of the component (a-1)) is preferably 1.0 <R ≦ 3.0, preferably 1.5 <R <2.5.

  Further, if necessary, after completion of the addition reaction, (a-3) a polyvalent carboxylic acid and / or a polyvalent carboxylic acid anhydride is further added, and at about 100 to 185 ° C. for about 0.5 to 6 hours. It is also possible to introduce an acid group by heating and reacting.

  The polyvalent carboxylic acid of the component (a-3) is a compound having two or more carboxyl groups in one molecule. For example, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, azelaic acid, Sebacic acid, 2,4-diethylglutaric acid, naphthalenedicarboxylic acid, 4,4-diphenyldicarboxylic acid, diphenylmethane-4,4'-dicarboxylic acid, het acid, maleic acid, fumaric acid, itaconic acid, trimellitic acid, pyro Mellitic acid, hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, tetrahydrophthalic acid, hexahydrotrimellitic acid, methylhexahydrophthalic acid, etc. can be mentioned, and these can be used alone or in combination of two or more. Can be used.

  The polycarboxylic acid anhydride as the component (a-3) is a compound having one or more acid anhydride groups in one molecule, and examples thereof include the above polyhydric carboxylic acid anhydrides. . Here, it is assumed that one acid anhydride group is divalent or bifunctional.

  In the reaction for introducing an acid group carried out as necessary, the proportion of the components (a-1), (a-2) and (a-3) used is the number of oligomers (A-1) obtained. The average molecular weight, acid value, and hydroxyl value are selected to be in the above-described ranges.

Polyester resin (A-2)
The polyester resin (A-2) of this paint synthesizes the oligomer (A-1), and (a-3) a polyvalent carboxylic acid and / or a polyvalent It is a polyester resin obtained by reacting a carboxylic acid anhydride and / or (a-4) a polyisocyanate compound to increase the molecular weight.

  In the above synthesis, in order to react the oligomer (A-1) with the polyvalent carboxylic acid and / or the polyvalent carboxylic acid anhydride (a-3), (A-1) and (a-3) are prepared by a conventional method. In a nitrogen stream, for example, it can be carried out by heating at about 150 to 250 ° C. for 1 to 10 hours to cause a condensation reaction. In this case, known esterification catalysts such as dibutyltin oxide, antimony trioxide, zinc acetate, manganese acetate, cobalt acetate, calcium acetate, lead acetate, tetrabutyl titanate, and tetraisopropyl titanate can be used.

  As the component (a-3), those mentioned for the oligomer (A-1) can be used in the same manner.

  In particular, the (a-3) component in the polyester resin (A-2) is preferably a trifunctional or higher polyhydric carboxylic acid and / or polyhydric carboxylic anhydride, and in particular, trimellitic anhydride, ethylene glycol. At least one compound selected from bis (anhydrotrimellitate), 1,3-propanediol bis (anhydrotrimellitate) and pyromellitic anhydride can be preferably used.

  In order to react the polyisocyanate compound (a-4) with the oligomer (A-1), (A-1) and (a-4) are reacted in a nitrogen stream by a conventional method, for example, at 60 to 140 ° C., Heating for 10 hours can be carried out by addition reaction of a hydroxyl group and an isocyanate group. In this case, an organometallic catalyst (particularly an organic tin catalyst) described later can be used as necessary.

  If necessary, after completion of the addition reaction with the isocyanate compound, the component (a-3) is further added, and the reaction is carried out by heating at about 100 to 185 ° C. for about 0.5 to 6 hours. Can also be introduced. As the component (a-3) in this case, those mentioned in the above-mentioned oligomer (A-1) can be used in the same manner.

  In the polyester resin (A-2), since the polyester resin obtained by reacting the oligomer (A-1) with the polyisocyanate compound (a-4) has a urethane bond in the resin skeleton, the physical properties can be improved.

  Examples of the polyisocyanate compound (a-4) include aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, and lysine diisocyanate; and burette-type adducts of these polyisocyanates, isocyanurates Cycloadduct; isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4- (or-2,6-) diisocyanate, 1,3- (or 1,4-) di (isocyanato Methyl) cyclohexane, 1,4-cyclohexane diisocyanate, 1,3-cyclopentane diisocyanate, 1,2-cyclohexane diisocyanate and other alicyclic diisocyanates; -Bullet type adducts of polyisocyanates, isocyanurate cycloadducts; xylylene diisocyanate, metaxylylene diisocyanate, tetramethyl xylylene diisocyanate, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene Diisocyanate, 1,4-naphthalene diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, (m- or p-) phenylene diisocyanate, 4,4'-biphenylene diisocyanate, 3,3 Aromatic diisocyanates such as' -dimethyl-4,4'-biphenylene diisocyanate, bis (4-isocyanatophenyl) sulfone, isopropylidenebis (4-phenylisocyanate) And burette type adducts, isocyanurate cycloadducts of these polyisocyanates; triphenylmethane-4,4 ′, 4 ″ -triisocyanate, 1,3,5-triisocyanatobenzene, Polyisocyanates having three or more isocyanate groups in one molecule such as 2,4,6-triisocyanatotoluene, 4,4′-dimethyldiphenylmethane-2,2 ′, 5,5′-tetraisocyanate; and Burette type adducts, isocyanurate cycloadducts of these polyisocyanates; hydroxyl groups of polyols such as ethylene glycol, propylene glycol, 1,4-butylene glycol, dimethylolpropionic acid, polyalkylene glycol, trimethylolpropane and hexanetriol Is excessive isocyanate group Examples thereof include urethanated adducts obtained by reacting polyisocyanate compounds in excess ratios; and burette-type adducts and isocyanurate cycloadducts of these polyisocyanates; and the like.

  In the synthesis of the polyester resin (A-2), when both the component (a-3) and the component (a-4) are reacted with the oligomer (A-1), the component (a-3), (a- 4) Any of the components may be reacted with the oligomer (A-1) first. The reaction at that time can be carried out under the same conditions as described above.

  The resulting polyester resin (A-2) has a number average molecular weight in the range of 400 to 6000, preferably in the range of 500 to 5000, a hydroxyl value in the range of 10 to 200 mgKOH / g, preferably 30 to 150 mgKOH / g, and 10 It can have an acid value in the range of -100 mg KOH / g, preferably 20-70 mg KOH / g. When the number average molecular weight of the polyester resin (A-2) is larger than 6000, high solid differentiation becomes difficult, and when the hydroxyl value is smaller than 10 mgKOH / g, the curability tends to be insufficient.

  The use ratio and reaction conditions of the oligomer (A-1) and component (a-3) and / or component (a-4) are the acid value, hydroxyl value and number average molecular weight of the resulting polyester resin (A-2). Is adjusted to be within the above-mentioned range.

  The oligomer (A-1) and the polyester resin (A-2) are usually 0.3 to 1.2 equivalents, preferably 0.5 to 1.0 equivalents of basic compound for each acid group. An aqueous resin composition can be prepared by dissolving or dispersing in an aqueous medium. Examples of the basic compound include inorganic basic compounds such as alkali metal hydroxides and aqueous ammonia; methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, isopropylamine, diisopropylamine, diethylenetriamine, triethylene Tetramine, monoethanolamine, diethanolamine, 2-amino-2-methylpropanol, morpholine, N-methylmorpholine, N-ethylmorpholine, piperazine, 2- (dimethylamino) ethanol, 2- (diethylamino) ethanol, dimethyldodecylamine, etc. These amine compounds can be mentioned. Of these, triethylamine, 2- (dimethylamino) ethanol, and 2- (diethylamino) ethanol are particularly preferable.

Cross-linking agent (B)
The crosslinking agent (B) of the present paint is not particularly limited, and examples thereof include a blocked polyisocyanate curing agent (b ₁ ), a water dispersible blocked polyisocyanate curing agent (b ₂ ), and a melamine resin described below. (B ₃ ) and the like can be preferably used.

The blocked polyisocyanate curing agent (b ₁ ) is obtained by blocking an isocyanate group of a polyisocyanate compound having two or more free isocyanate groups in one molecule with a blocking agent.

  Examples of the polyisocyanate compound include aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, and lysine diisocyanate; burette type adducts of these aliphatic polyisocyanates, isocyanurate ring addition Isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4- (or-2,6-) diisocyanate, 1,3- (or 1,4-) di (isocyanatomethyl) Cycloaliphatic diisocyanates such as cyclohexane, 1,4-cyclohexane diisocyanate, 1,3-cyclopentane diisocyanate, 1,2-cyclohexane diisocyanate; Bullet type adduct of alicyclic diisocyanate, isocyanurate ring adduct; xylylene diisocyanate, tetramethylxylylene diisocyanate, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate (MDI), 1,5-naphthalene Diisocyanate, 1,4-naphthalene diisocyanate, 4,4′-toluidine diisocyanate, 4,4′-diphenyl ether diisocyanate, (m- or p-) phenylene diisocyanate, 4,4′-biphenylene diisocyanate, 3,3 Aromatic diisocyanate compounds such as' -dimethyl-4,4'-biphenylene diisocyanate, bis (4-isocyanatophenyl) sulfone, isopropylidenebis (4-phenylisocyanate); and these Burelet type adduct of isocyanate, isocyanurate cycloadduct; hydrogenated MDI, and derivatives of hydrogenated MDI; triphenylmethane-4,4 ′, 4 ″ -triisocyanate, 1,3,5-triisocyanate It has three or more isocyanate groups in one molecule such as natobenzene, 2,4,6-triisocyanatotoluene, 4,4′-dimethyldiphenylmethane-2,2 ′, 5,5′-tetraisocyanate. Polyisocyanates; burette type adducts and isocyanurate cycloadducts of these polyisocyanates; ethylene glycol, propylene glycol, 1,4-butylene glycol, dimethylolpropionic acid, polyalkylene glycol, trimethylolpropane, hexanetriol, etc. Isocyanate to the hydroxyl group of Examples thereof include urethanated adducts obtained by reacting polyisocyanate compounds in an excess amount of nate groups; burette type adducts, isocyanurate ring adducts, and the like of these urethanized adducts.

Further, the blocking agent blocks free isocyanate groups in these polyisocyanate compounds. For example, when heated to 100 ° C. or higher, preferably 130 ° C. or higher, the blocking agent dissociates to form free isocyanate groups. It can be regenerated and easily reacted with hydroxyl groups. Examples of the blocking agent include phenols such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and hydroxybenzoic acid methyl; ε-caprolactam, δ-valerolactam, Lactams such as γ-butyrolactam, β-propiolactam; aliphatic alcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, lauryl alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono Butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether Ethers such as propylene glycol monomethyl ether and methoxymethanol; benzyl alcohol; glycolic acid; glycolic acid esters such as methyl glycolate, ethyl glycolate, and butyl glycolate; lactic acid esters such as lactic acid, methyl lactate, ethyl lactate, and butyl lactate Alcohol system such as methylol urea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate; formamide oxime, acetamide oxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexane oxime, etc. Oxime system;
Malonic acid dialkyl esters such as dimethyl malonate, diethyl malonate, diisopropyl malonate, di-n-butyl malonate, diethyl methylmalonate, benzylmethyl malonate, diphenyl malonate, methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate Active methylenes such as acetoacetate such as n-propyl acetoacetate, benzyl acetoacetate and phenylacetoacetate, phenylacetoacetate, and acetylacetone; Mercaptans such as phenol, methylthiophenol, ethylthiophenol; acetanilide, acetanisidide, acetolide, acrylamide, methacrylamide, acetic acid amide Acid amides such as stearamide, benzamide; imides such as succinimide, phthalimide, maleic imide; diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine Amines such as butylphenylamine; imidazoles such as imidazole and 2-ethylimidazole; pyrazoles such as 3,5-dimethylpyrazole; ureas such as urea, thiourea, ethyleneurea, ethylenethiourea and diphenylurea; N -Blocking agents such as carbamate esters such as phenyl phenyl carbamate; imines such as ethylene imine and propylene imine; and sulfites such as sodium bisulfite and potassium bisulfite. That.

In order to reduce the amount of organic solvent in paints (lower VOC), it is better to reduce the amount of organic solvent from the cross-linking agent (B). A blocked polyisocyanate curing agent (b ₂ ) obtained by imparting water dispersibility to the agent (b ₁ ) can be used.

In the blocked polyisocyanate curing agent (b ₂ ) imparted with water dispersibility, for example, the isocyanate group of the polyisocyanate compound is blocked with a blocking agent containing hydroxymonocarboxylic acids, and carboxyl groups introduced by hydroxymonocarboxylic acids are introduced. A blocked polyisocyanate compound imparted with water dispersibility by neutralizing can be mentioned. In this case, it is preferable from the viewpoint of water dispersibility of the resulting blocked polyisocyanate curing agent that the polyisocyanate compound is reacted so that at least one isocyanate group is added to the hydroxyl group of the hydroxymonocarboxylic acid.

As the polyisocyanate compound, polyisocyanate compounds similar to those exemplified in the blocked polyisocyanate curing agent (b ₁ ) can be used, and among them, hexamethylene diisocyanate (HMDI), hexamethylene diisocyanate (HMDI) are particularly preferable. ) Derivatives, isophorone diisocyanate (IPDI), isophorone diisocyanate (IPDI) derivatives, hydrogenated MDI and hydrogenated MDI derivatives.

As the blocking agent, the same blocking agent as exemplified in the blocked polyisocyanate curing agent (b ₁ ) can be used. Examples of hydroxy monocarboxylic acids include 2-hydroxyacetic acid, 3-hydroxypropanoic acid, 12-hydroxy-9-octadecanoic acid (ricinoleic acid), 3-hydroxy-2,2-dimethylpropanoic acid (hydroxypivalic acid). ), 2,2-dimethylolpropionic acid (DMPA) and the like, among which 3-hydroxy-2,2-dimethylpropanoic acid (hydroxypivalic acid) is preferable. The reaction can be carried out in a solvent that is not reactive with an isocyanate group, for example, a ketone such as acetone or methyl ethyl ketone, an ester such as ethyl acetate, or a solvent such as N-methylpyrrolidone (NMP).

Specific examples of the melamine resin (b ₃ ) include di-, tree, tetra-, penta-, hexa-methylol melamine and alkyl etherified products thereof (for example, methyl, ethyl, propyl, isopropyl, Butyl, isobutyl, 2-ethylhexyl alcohol, etc.) and condensates thereof. Examples of commercially available products include Cymel series such as Cymel 254 manufactured by Nippon Cytec Industries, Inc .; manufactured by Mitsui Chemicals, Inc. Uban series such as Uban 20SB can be used.
When melamine resin (b ₃ ) is used as a curing agent, sulfonic acids such as paratoluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, and salts of these acids with amines are used as catalysts. can do.

Water dispersible polymer particles (C)
The water-dispersible polymer particles (C) of the present paint are not particularly limited, and those usually used in water-based paints can be used in the same manner. Preferred examples include acrylic resins and polyester resins. (Including alkyd resins), water-dispersed products such as epoxy resins and urethane resins, and any of these having a hydroxyl group, a carboxyl group or the like in its molecular structure can be suitably used.

  Among these, the water-dispersible acrylic polymer particles (C-1) and the water-dispersible urethane polymer particles (C-2) described below are particularly preferable, and can be suitably used particularly for water base coat coating applications.

Water dispersible acrylic polymer particles (C-1)
Water-dispersible acrylic polymer particles obtained by emulsion polymerization of a vinyl monomer using a radical polymerization initiator in the presence of a dispersion stabilizer such as a surfactant.

  The water dispersible acrylic polymer particles (C-1) may have any structure of a normal structure or a multilayer structure such as a core / shell structure. Moreover, any type of an intraparticle non-crosslinked type or an intraparticle crosslinked type may be used. In the core / shell structure, for example, both the core part and the shell part can be of a crosslinked type or an uncrosslinked type, for example, the core part is an intra-particle crosslinked type and the shell part is an uncrosslinked type.

  The vinyl monomer to be emulsion polymerized is preferably selected from a carboxyl group-containing vinyl monomer (M-1), a hydroxyl group-containing vinyl monomer (M-2), and other vinyl monomers (M-3). A method of using a small amount of a polyvinyl compound (M-4) having two or more saturated bonds in one molecule, and a small amount of each of a vinyl monomer having a glycidyl group and a carboxyl group-containing vinyl monomer (M-1) in one molecule Intraparticle crosslinked water-dispersible acrylic polymer particles can be obtained by the combined use method, the hydroxyl group-containing vinyl monomer (M-2) and the vinyl monomer having an isocyanate group in one molecule in small amounts. .

  Specifically, the water-dispersible acrylic polymer particles (C-1) having a core / shell structure include, for example, a vinyl monomer component containing no or almost no carboxyl group-containing vinyl monomer (M-1) at first. It can be obtained by emulsion polymerization and then emulsion polymerization by adding a vinyl monomer component containing a large amount of carboxyl group-containing vinyl monomer (M-1).

  Specifically, the water-dispersible acrylic polymer particle (C-1) having a core / crosslinked core / shell structure is, for example, a small amount of a polyvinyl compound (M-4) and a carboxyl group-containing vinyl monomer ( Obtained by emulsion polymerization of a vinyl monomer component containing no or little M-1), and then emulsion polymerization by adding a vinyl monomer component containing a large amount of carboxyl group-containing vinyl monomer (M-1). Can do.

  The bond between the core part and the shell part is, for example, a polymerizable unsaturated bond introduced via a hydrolyzable functional group or silanol group provided on the surface of the core part, or an allyl remaining on the surface of the core part ( The polymerization can be carried out by copolymerizing a polymerizable unsaturated bond derived from (meth) acrylate with a vinyl monomer component containing a carboxyl group-containing vinyl monomer (M-1) (a shell portion is formed).

  The carboxyl group-containing vinyl monomer (M-1) includes compounds having one or more carboxyl groups and one polymerizable unsaturated bond in one molecule, such as acrylic acid, methacrylic acid, crotonic acid. , Maleic acid, itaconic acid and the like. Furthermore, acid anhydrides and half-esterified monocarboxylic acids of these compounds are included in the monomer (M-1) in the present specification.

  The hydroxyl group-containing vinyl monomer (M-2) includes a compound having a hydroxyl group and a polymerizable unsaturated bond in one molecule, and this hydroxyl group can act as a functional group that reacts with a crosslinking agent. As the monomer (M-2), specifically, a monoesterified product of acrylic acid or methacrylic acid and a dihydric alcohol having 2 to 10 carbon atoms is suitable, for example, 2-hydroxyethyl acrylate, 2 -Hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate and the like, and N-methylol acrylamide, N-methylol methacrylamide and the like can be mentioned.

  Other vinyl monomers (M-3) include monomers other than the above-mentioned monomers (M-1) and (M-2) and having one polymerizable unsaturated bond in one molecule. Specific examples thereof are listed in the following (1) to (8).

  (1) Monoesterified product of acrylic acid or methacrylic acid and monohydric alcohol having 1 to 20 carbon atoms: for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, lauryl acrylate, lauryl methacrylate, and the like.

  (2) Aromatic vinyl monomers: For example, styrene, α-methylstyrene, vinyltoluene and the like.

  (3) Glycidyl group-containing vinyl monomer: a compound having one glycidyl group and one polymerizable unsaturated bond in each molecule, specifically, glycidyl acrylate, glycidyl methacrylate, and the like.

  (4) Nitrogen-containing alkyl (C1-20) acrylate: for example, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate and the like.

  (5) Polymerizable unsaturated bond-containing amide compounds: for example, acrylic acid amide, methacrylic acid amide, dimethylacrylamide, N, N-dimethylpropylacrylamide, N-butoxymethylacrylamide, diacetone acrylamide and the like.

  (6) Vinyl compound: For example, vinyl acetate, vinyl propionate, vinyl chloride and the like.

  (7) Polymerizable unsaturated bond-containing nitrile compounds: for example, acrylonitrile, methacrylonitrile and the like.

  (8) Diene compounds: for example, butadiene, isoprene and the like.

  These other vinyl monomers (M-3) can be used alone or in combination of two or more.

  Examples of the polyvinyl compound (M-4) include ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol diacrylate, tetraethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, allyl methacrylate, and allyl acrylate. , Divinylbenzene, trimethylolpropane triacrylate, methylenebisacrylamide and the like, and the diene compound is not included here.

  On the other hand, examples of the dispersion stabilizer used in the emulsion polymerization include an anionic emulsifier, a nonionic emulsifier, and an amphoteric ion emulsifier. Specifically, examples of the anionic emulsifier include fatty acids, alkyl sulfate esters, alkylbenzene sulfonates, and alkyl phosphates. Examples of nonionic emulsifiers include polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene derivatives, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkyl amines, alkyl alkanolamides, and the like. . Examples of the zwitterionic emulsifier include alkylbedine.

  The concentration of these emulsifiers is suitably within the range of 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the solid content weight of the water-dispersible acrylic polymer particles.

  Examples of the radical polymerization initiator include ammonium persulfate and 4,4′-azobis (4-cyanobutanoic acid). The amount of the initiator used is the solid content weight of the water-dispersible acrylic polymer particles. In general, the range of 0.01 to 10% by weight, preferably 0.1 to 5% by weight is suitable.

  The reaction temperature during emulsion polymerization is usually 60 to 90 ° C., and the reaction time is usually 5 to 10 hours.

  The obtained water-dispersible acrylic polymer particles (C-1) are generally hydroxyl groups in the range of 1 to 100 mgKOH / g, preferably 5 to 80 mgKOH / g, from the viewpoint of water resistance and curability of the resulting coating film. It is preferable to have a valence. The water-dispersible acrylic polymer particles (C-1) are generally in the range of 1 to 100 mgKOH / g, preferably 5 to 80 mgKOH / g, from the viewpoint of water resistance and curability of the resulting coating film. It preferably has an acid value. Further, the water-dispersible acrylic polymer particles (C-1) can generally have a particle diameter in the range of 10 to 1000 nm, preferably 20 to 500 nm.

The water-dispersible acrylic polymer particles (C-1) are preferably neutralized with a basic compound.
Neutralizing agents for water-dispersible acrylic polymer particles (C-1) include ammonia or water-soluble amino compounds such as monoethanolamine, ethylamine, dimethylamine, diethylamine, triethylamine, propylamine, dipropylamine, Isopropylamine, diisopropylamine, triethanolamine, butylamine, dibutylamine, 2-ethylhexylamine, ethylenediamine, propylenediamine, methylethanolamine, dimethylethanolamine, diethylethanolamine, 2-amino-2-methylpropanol, diethanolamine, morpholine, etc. Can be preferably used.

Water dispersible urethane polymer particles (C-2)
Water-dispersible urethane polymer particles (C-2) are used, for example, for the purpose of improving coating film properties such as stress relaxation effects. For example, when used for automobile applications, the coating film is running. It is effective in improving the damage resistance (referred to as chipping resistance) and the like of the coating film by stone splash.

  Water-dispersible urethane polymer particles (C-2) are a urethane polymer obtained by reacting an active hydrogen-containing compound, a compound having an active hydrogen and an anion group or an anion-forming group in the molecule, and an organic polyisocyanate compound. Can be obtained by dispersing or dissolving in water.

  Examples of the active hydrogen-containing compound include high-molecular polyols, low-molecular polyols, and polyamines (for example, those described in JP-A-3-9951).

  As the polymer polyol, polyether polyol, polyester polyol and polycarbonate polyol are preferable. The polymer polyol may have an OH group equivalent within a range of usually 200 to 3000, preferably 250 to 2000. As the low molecular weight polyol, 1,4-butanediol, 3-methylpentanediol, pentaerythritol and trimethylolpropane are preferable. As the polyamine, hexamethylenediamine, isophoronediamine, N-hydroxyethylethylenediamine, and 4,4'-diaminodicyclohexylmethane are preferable.

  Examples of the compound having an active hydrogen and an anion group or an anion-forming group in the molecule include dihydroxycarboxylic acid (α, α′-dimethylolpropionic acid, α, α′-dimethylolbutyric acid, etc.), dihydroxysulfonic acid compound, and the like. [3- (2,3-dihydroxypropoxy) -1-propanesulfonic acid sodium salt and the like] and diaminocarboxylic acid (for example, diaminobenzoic acid and the like), and as a basic compound for neutralizing these, An organic base (for example, triethylamine, trimethylamine, etc.) and an inorganic base (for example, sodium hydroxide, potassium hydroxide, etc.) are mentioned.

  Examples of the organic polyisocyanate compound include isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI), 2,4 or 2,6-tolylene diisocyanate (TDI). 4,4′-diphenylmethane diisocyanate (MDI), α, α, α ′, α′-tetramethylxylylene diisocyanate (TMXDI), and the like.

  In producing the urethane polymer, the reaction of the active hydrogen-containing compound, the active hydrogen in the molecule, the compound having an anion group or an anion-forming group, and the organic polyisocyanate compound is a one-shot reaction in which each component is reacted at once. Or, for example, by reacting a part of an active hydrogen-containing compound (for example, a polymer polyol), a compound having an active hydrogen and an anion group or an anion-forming group in the molecule, and an organic polyisocyanate compound. After the prepolymer is formed, it can be carried out by any of the multistage methods in which the remainder of the active hydrogen-containing compound is reacted.

  Said reaction can be normally performed at 40-140 degreeC, Preferably it is 60-120 degreeC. The reaction may be carried out in an organic solvent inert to isocyanate (acetone, toluene, dimethylformamide, etc.), and the organic solvent may be added either during or after the reaction.

  Water-dispersible urethane polymer particles (C-2) are obtained by neutralizing a urethane polymer having a hydrophilic group obtained as described above with a basic compound to form an anionic group, and then dispersing or dispersing in water. It can be obtained by dissolving.

  In addition, when the urethane polymer is dispersed or dissolved in water, an anionic and / or nonionic surfactant can be used in combination as necessary.

  The thermosetting water-based paint of the present invention, for example, produces an aqueous varnish by dissolving or dispersing the oligomer (A-1) and / or the polyester resin (A-2) in an aqueous medium containing a neutralizing base. In addition, it can be adjusted by adding and dispersing the crosslinking agent of component (B) and water-dispersible polymer particles of component (C). At that time, the neutralizing base can be usually used within a range where the pH of the thermosetting water-based paint is 7-9.

  The amount of (A) oligomer (A-1) and / or polyester resin (A-2), (B) cross-linking agent, and (C) water-dispersible polymer particles in the paint is strictly limited. Rather, it can be varied over a wide range depending on the application of the paint, etc., but in general, as a solid content based on 100 parts by weight of resin solid content in the thermosetting water-based paint, (A) oligomer (A -1) and / or polyester resin (A-2) in the range of 5 to 50% by weight, preferably 5 to 40% by weight, and the crosslinking agent (B) in the range of 5 to 60% by weight, preferably 10 to 40% by weight. And the water-dispersible polymer particles (C) can be in the range of 5 to 80% by weight, preferably 20 to 60% by weight.

  In addition to the components (A), (B) and (C) described above, the present paint may further contain other resins as necessary. Examples of such a resin include an acrylic resin, a polyester resin, a urethane-modified polyester resin, and an epoxy resin. Among them, the acrylic resin and the polyester resin described below are preferable.

It is an acrylic resin that can be synthesized by copolymerizing an acrylic resin radical polymerizable monomer by solution polymerization according to a conventional method. As an organic solvent that can be used for solution polymerization, for example, a hydrophilic organic solvent such as a propylene glycol type or a dipropylene glycol type is preferable. From the viewpoint of water dispersibility, the acrylic resin preferably has an acid group such as a carboxyl group.

As the radical polymerizable monomer, conventionally known monomers can be used, and for example, a hydroxyl group-containing radical polymerizable monomer, a carboxyl group-containing radical polymerizable monomer, and other radical polymerizable monomers can be used.
Examples of the hydroxyl group-containing radical polymerizable monomer include 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, and ε-caprolactone-modified tetrahydrofur. Furyl (meth) acrylate, ε-caprolactone-modified hydroxyethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-hydroxy- Examples thereof include 3-butoxypropyl (meth) acrylate and monohydroxyethyl (meth) acrylate phthalate.

  Examples of the carboxyl group-containing radical polymerizable monomer include acrylic acid and methacrylic acid.

  Examples of other radical polymerizable monomers include styrene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and cyclohexyl (meth) acrylate. , Cyclohexenyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) ) Acrylate, Aronix M110 (Toagosei), N-methylol (meth) acrylamide, N-butoxy (meth) acrylamide, acryloylmorpholine, Methylaminoethyl (meth) acrylate, N- vinyl-2-pyrrolidone, .gamma. acrylate etc. b propyl trimethoxysilane can be exemplified.

  In the above, “(meth) acrylate” means “acrylate or methacrylate”.

  The acrylic resin generally has a weight average molecular weight in the range of 1,000 to 200,000, preferably 2,000 to 100,000. The acrylic resin generally has a hydroxyl value in the range of 10 to 250 mg KOH / g, preferably in the range of 30 to 150 mg KOH / g and generally an acid value in the range of 10 to 100 mg KOH / g, preferably 20 to 60 mg KOH / g. it can.

  When an acrylic resin is used, the amount thereof is 0.1 to 35% by weight, preferably 1 to 30% by weight, based on 100 parts by weight of resin solids in the thermosetting water-based paint. can do.

Polyester resin Other than the polyester resin (A-2) of the present paint, it is a polyester resin that can be synthesized by a known method usually by esterifying a polybasic acid and a polyhydric alcohol.

  A polybasic acid is a compound having two or more carboxyl groups in one molecule. For example, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, tetrahydrophthalic acid, hexahydrophthalic acid Examples thereof include acid, hetic acid, maleic acid, fumaric acid, itaconic acid, trimellitic acid, and anhydrides thereof, and polyhydric alcohol is a compound having two or more hydroxyl groups in one molecule. Examples thereof include ethylene glycol, propylene glycol, butylene glycol, hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

  In addition, as the polyester resin, sesame oil fatty acid, coconut oil fatty acid, safflower oil fatty acid, soybean oil fatty acid, sesame oil fatty acid, eno oil fatty acid, hemp oil fatty acid, toll oil fatty acid, dehydrated castor oil fatty acid, etc. (half) A fatty acid-modified polyester resin modified with a dry oil fatty acid or the like can also be used. In general, the amount of modification with these fatty acids is preferably 30% by weight or less in terms of oil length. Further, a product obtained by partially reacting a monobasic acid such as benzoic acid may be used. Further, for example, in order to introduce an acid group into a polyester resin, after the esterification reaction of the polybasic acid and the polyhydric alcohol, a polybasic acid such as trimellitic acid or trimellitic anhydride and an anhydride thereof are further added. It can also be reacted.

  The polyester resin generally has a weight average molecular weight in the range of 1,000 to 200,000, preferably 2,000 to 50,000. Also, the polyester resin generally has a hydroxyl value in the range of 10 to 250 mg KOH / g, preferably 30 to 150 mg KOH / g and generally an acid value in the range of 10 to 100 mg KOH / g, preferably 20 to 60 mg KOH / g. it can.

  (A-2) When using polyester resin other than a component, the quantity is 0.1-35 weight% as solid content on the basis of 100 weight part of resin solid content in a thermosetting aqueous coating material, Preferably it is 1 It can be in the range of ˜30% by weight.

  If necessary, this paint may contain pigments, curing catalysts, UV absorbers, light stabilizers, surface conditioners, anti-degradation agents, anti-flow agents, anti-settling agents, and other usual paint additives. be able to.

  Examples of the pigment include titanium oxide, zinc white, carbon black, cadmium red, molybdenum red, chromium yellow, chromium oxide, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindoline pigment, selenium pigment, and perylene. Colored pigments such as pigments; extender pigments such as talc, clay, kaolin, barita, barium sulfate, barium carbonate, calcium carbonate, silica, and alumina white; bright pigments such as mica powder coated with aluminum powder, mica powder, and titanium oxide Etc.

  When this paint is used as a metallic-specific water-based base coat paint, a bright pigment and, if necessary, a color pigment can be added. The pigment can be made from a portion of the resin described above to make a pigment paste, which can be added to the remaining aqueous varnish along with other ingredients. In preparing the pigment paste, conventional additives such as an antifoaming agent, a dispersing agent, and a surface conditioner can be appropriately used as necessary.

  The blending amount of the pigment is generally 1 to 250 parts by weight, particularly 3 to 150 parts by weight per 100 parts by weight of the total solid content of the resin component.

Examples of the curing catalyst include organometallic, acid and base compounds.
Examples of organometallic compounds include tetraisopropyl titanate, tetrabutyl titanate, lithium acetate, acetylacetone iron (III), zinc 2-ethylhexanoate, copper acetate, vanadium trichloride, tin octylate, dibutyltin diacetate, Dibutyltin dioctoate, dibutyltin dilaurate, dibutyltin dimaleate, tetrabutyltin, dibutyltin oxide, tetra-n-butyl-1,3-diacetyloxydistanoxane, tetra-n-propyl-1,3-diacetyloxydistanoxane And metal catalysts such as tetra-n-butyl-1,3-dilauryloxydistanoxane, and particularly organotin compounds such as tin octylate, dibutyltin diacetate, dibutyltin dilaurate, and distanoxanes. Is preferred, and low temperature firing If the put is required, dibutyltin diacetate is preferably used.

  Examples of the acid compounds include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, butylphosphoric acid, octylphosphoric acid, and the like. Japanese products are also preferably used.

  Examples of the base compound include trimethylamine, triethylamine, dimethylcyclohexylamine, N-tetramethylhexane-1,6-diamine, N-pentamethyldiethylenetriamine, 2-methyl-1,4-diazabicyclo [2,2,2]. ] Compounds such as octane can be mentioned.

  These compounds described above as the curing catalyst can be used alone or in combination of two or more. The amount of the curing catalyst to be used varies depending on the kind thereof, but usually about 0.05 to 5 parts by weight is suitable for 100 parts by weight of the total solid content of the resin component.

  As the ultraviolet absorber, those known per se can be used, and examples thereof include a benzotriazole-based absorbent, a triazine-based absorbent, a salicylic acid derivative-based absorbent, and a benzophenone-based absorbent.

  When the ultraviolet absorber is contained, the content in the coating is usually 0.1 to 10 parts by weight, particularly 0.2 to 5 parts by weight, and more particularly 0. The range of 3 to 2 parts by weight is preferable in terms of weather resistance, yellowing resistance and the like.

  As the light stabilizer, those known per se can be used, and examples thereof include hindered amine light stabilizers.

  When the light stabilizer is contained, the content in the coating is usually 0.1 to 10 parts by weight, particularly 0.2 to 5 parts by weight, and more particularly 0. The range of 3 to 2 parts by weight is preferable from the viewpoint of weather resistance and yellowing resistance.

Coating Film Forming Method The material to which the present paint can be applied is not particularly limited, but for example, the body of various vehicles such as automobiles, motorcycles, and containers is preferable. In addition, cold rolled steel sheets, galvanized steel sheets, zinc alloy plated steel sheets, stainless steel sheets, tin plated steel sheets, etc. forming metal bodies; metal substrates such as aluminum plates and aluminum alloy plates; various plastic materials, etc. Good.

  Moreover, as a to-be-coated object, surface treatments, such as a phosphate process, a chromate process, a complex oxide process, may be given to the metal surface of the said vehicle body or a metal base material. Further, the object to be coated may be one in which an undercoat film and / or an intermediate coat film such as various electrodeposition paints are formed on the vehicle body, metal base material, and the like.

  The coating method of this paint is not particularly limited, and examples thereof include air spray coating, airless spray coating, rotary atomization coating, curtain coat coating, and the like, and a wet coating film is formed by these coating methods. Can do. These coating methods may be electrostatically applied as necessary. Among these, the air spray coating method is particularly preferable. The application amount of the thermosetting water-based paint is usually preferably an amount of about 10 to 70 μm as the cured film thickness.

  In the case of air spray coating, airless spray coating, and rotary atomization coating, the viscosity of the thermosetting water-based coating is adjusted to a viscosity range suitable for the coating, usually Ford Cup #No. In a 4-viscosity meter, it is preferable to adjust appropriately using an organic solvent and / or water so that the viscosity is within a range of about 15 to 60 seconds at 20 ° C.

  The wet coating film is cured by applying the paint to the article to be coated and then heating.

  Heating can be performed by a known heating means. For example, a drying furnace such as a hot air furnace, an electric furnace, or an infrared induction heating furnace can be used. The heating temperature is usually 80 to 180 ° C, preferably 100 to 160 ° C. The heating time is not particularly limited, but can usually be about 20 to 40 minutes.

  This coating material can be suitably used as a coating material for automobiles, and in particular, can be more suitably used as a topcoat base coat coating material.

  When used as a topcoat base coat, for example, this paint is applied onto an object to be coated with electrodeposition and / or intermediate coating, and the uncured coating is applied without curing the coating. By applying a clear coat paint on the film and simultaneously heating and curing the base coat and the clear coat, a multi-layer coating film can be formed by a 2-coat 1-bake method.

  In addition, an intermediate coating is applied on the object to be coated, and this coating is applied as an overcoat base coat on the uncured intermediate coating without curing the coating, and further the coating is cured. Rather than coating the uncured topcoat basecoat film with a clearcoat paint and heating and curing three layers of the intermediate coat, topcoat basecoat and clearcoat at the same time, a multi-layer by a three-coat one-bake method A coating film can also be formed.

  As the intermediate coating used in the above, a conventionally known thermosetting intermediate coating can be used. Specifically, for example, an amino acid is added to a base resin such as an alkyd resin, a polyester resin, an acrylic resin, or a urethane resin. A coating material obtained by appropriately combining a curing agent having reactivity with a reactive functional group contained in a base resin and a curing agent such as a resin, a polyisocyanate compound, or a block polyisocyanate compound can be used. As said polyisocyanate compound and block polyisocyanate compound, the same thing as described about the said crosslinking agent (B) can be used, for example. In addition, as the intermediate coating material, from the viewpoint of environmental problems, resource saving, etc., a high solid type coating material, a water-based coating material, a powder coating material, or the like that uses a small amount of organic solvent can also be used. Moreover, this coating material can also be used as an intermediate coating material in the said 3 coat 1 baking system.

  As the clear coat paint used in the above, a conventionally known thermosetting clear coat paint can be used. Specifically, for example, alkyd resin, polyester resin, acrylic resin, silicon resin, fluororesin, urethane Curing agents such as amino resins, polyisocyanate compounds, block polyisocyanate compounds, polycarboxylic acids or their anhydrides, and reactive silane compounds are reacted with the reactive functional groups contained in the base resin. An organic solvent diluted paint obtained by appropriately combining the curing agents having them can be used. As said polyisocyanate compound and block polyisocyanate compound, the same thing as described about the said crosslinking agent (B) can be used, for example. In addition, as the clear coat paint, from the viewpoint of environmental problems, resource saving, etc., a high solid type paint, water-based paint, powder paint or the like with a small amount of organic solvent can be used.

  In particular, an acrylic resin / melamine resin system, an acrylic resin / polyisocyanate curing agent system, an acrylic resin / block polyisocyanate curing agent system, or an acid group-containing resin / epoxy group-containing resin system can be suitably used.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited only to these examples. “Part” and “%” are both based on weight, and the film thickness of the coating film is based on the cured coating film.
(Example)
Production Example of Oligomer (A-1) (Production Example 1)
A reactor equipped with a stirrer, reflux condenser, water separator and thermometer was charged with 190 parts of 1,2,4-butanetricarboxylic acid and 490 parts of Cardura E10P (Japan Epoxy Resin, Neodecanoic acid monoglycidyl ester). The oligomer 1 having a hydroxyl value of 164 mgKOH / g, an acid value of 82 mgKOH / g, and a number average molecular weight of 690 was obtained by reacting at 120 ° C. for 3 hours.
(Production Example 2)
A reactor equipped with a stirrer, reflux condenser, water separator and thermometer was charged with 218 parts of 1,3,6-hexanetricarboxylic acid and 490 parts of Cardura E10P and reacted at 120 ° C. for 3 hours to obtain a hydroxyl value. An oligomer 2 having 158 mgKOH / g, an acid value of 79 mgKOH / g, and a number average molecular weight of 710 was obtained.

Production example of polyester resin (A-2) (Production Example 3)
A reactor equipped with a stirrer, reflux condenser, water separator and thermometer was charged with 190 parts of 1,2,4-butanetricarboxylic acid and 613 parts of Cardura E10P, reacted at 120 ° C. for 4 hours, and raised to 230 ° C. Warmed and allowed to react for another 2 hours. Thereafter, the mixture was cooled to 160 ° C., 96 parts of trimellitic anhydride was added and reacted for 3 hours to obtain a polyester resin 1 having a hydroxyl value of 80 mgKOH / g, an acid value of 49 mgKOH / g, and a number average molecular weight of 2000. .
(Production Example 4)
The reaction was conducted in the same manner as in Production Example 3 except that 218 parts of 1,3,6-hexanetricarboxylic acid was used instead of 190 parts of 1,2,4-butanetricarboxylic acid in Production Example 3, and the hydroxyl value was A polyester resin 2 having 75 mgKOH / g, an acid value of 45 mgKOH / g, and a number average molecular weight of 2200 was obtained.
(Production Example 5)
In a reactor equipped with a stirrer, reflux condenser, water separator and thermometer, 218 parts of 1,3,6-hexanetricarboxylic acid and 613 parts of Cardura E10P were charged and reacted at 120 ° C. for 4 hours. Then, it cooled to 80 degreeC, 111 parts of isophorone diisocyanate was prepared, and it was made to react at 80 degreeC for 6 hours. Thereafter, 29 parts of trimellitic anhydride was added and reacted at 180 ° C. for 1 hour to obtain a polyester resin 3 having a hydroxyl value of 89 mgKOH / g, an acid value of 46 mgKOH / g, and a number average molecular weight of 2000.
(Production Example 6)
In a reactor equipped with a stirrer, reflux condenser, water separator and thermometer, 95.6 parts of trimethylolpropane, 120.4 parts of 1,6-hexanediol, 169.4 parts of hexahydrophthalic anhydride, succinic anhydride 60 parts and 68.6 parts of Cardura E10P were charged, the temperature was raised between 160 ° C. and 230 ° C. over 3 hours, and then reacted at 230 ° C. for 4 hours. Next, in order to add a carboxyl group to the obtained reaction product, 42.2 parts of trimellitic anhydride was further added and reacted at 180 ° C. for 1 hour to have a hydroxyl value of 118 mgKOH / g and an acid value of 49 mgKOH / g. Polyester resin 4 having a number average molecular weight of 1700 was obtained.

Production Example of Crosslinking Agent (B) (Production Example 7)
A reactor equipped with a thermometer, a thermostat, a stirrer, a reflux condenser, a dropping pump, and the like was added to Sumidur N-3300 (manufactured by Sumitomo Bayer Urethane Co., Ltd., isocyanurate structure-containing polyisocyanurate, number average molecular weight of about 600, isocyanurate content 21 .6%) 605 parts, diethyl malonate 413 parts, and ethyl acetate 181 parts were mixed, 7.0 parts of a 28% sodium hydroxide methanol solution was added under a nitrogen stream, and the mixture was kept at 60 ° C. for 12 hours. Thereafter, when the NCO value was measured, the isocyanate content was 0.2%. 99 parts of ethyl acetate was added thereto to obtain a resin solution. Take 505 parts of this resin solution into another similar reactor, add 450 parts of propylene glycol monopropyl ether, raise the temperature to 90 ° C., and maintain the system temperature at 80 to 90 ° C. for 2 hours under reduced pressure conditions. The solvent was distilled off and removed to obtain 624 parts of a blocked polyisocyanate curing agent solution. The removal solvent simple trap contained 42 parts of ethanol. The obtained blocked polyisocyanate curing agent solution was diluted with propylene glycol monopropyl ether to obtain a blocked polyisocyanate curing agent solution 1 having a solid content of 80%. The number average molecular weight of the blocked polyisocyanate curing agent was about 1,800.

Production example of water-dispersible polymer particles (C) (Production Example 8)
A reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser and dropping device was charged with 145 parts of deionized water and 1.2 parts of Newcol 562SF (Note 1), stirred and mixed in a nitrogen stream, and heated to 80 ° C. Warm up. Subsequently, 1% of the total amount of the following monomer emulsion 1 and 5.2 parts of a 3% aqueous solution of ammonium persulfate were introduced into the reaction vessel and maintained at 80 ° C. for 15 minutes. Then, the remaining monomer emulsion 1 was dripped in reaction container over 3 hours, and it age | cure | ripened for 1 hour after completion | finish of dripping. Thereafter, 1.5 parts of the following monomer emulsion 2 and 3% aqueous ammonium persulfate solution were added dropwise over 2 hours, and after aging for 1 hour, 89 parts of 1.5% aqueous dimethylethanolamine solution was gradually added to the reaction vessel. Cool to 30 ° C, discharge while filtering through 100 mesh nylon cloth, and dilute with deionized water using an average particle size of 100 nm (submicron particle size distribution analyzer “COULTER N4 type” (Beckman Coulter, Inc.) And water-dispersible acrylic polymer particles 1 (solid content 25.2%) having an acid value of 30.7 mgKOH / g and a hydroxyl value of 22.1 mgKOH / g.
(Note 1) Newcol 562SF; manufactured by Nippon Emulsifier Co., Ltd., trade name, ammonium polyoxyethylene alkylbenzenesulfonate, active ingredient 60%.

  Monomer emulsion 1: 94.3 parts of deionized water, 17 parts of methyl methacrylate, 80 parts of n-butyl acrylate, 3 parts of allyl methacrylate and 1.2 parts of Newcol 562SF were mixed and stirred to obtain monomer emulsion 1.

  Monomer emulsion 2: 39 parts of deionized water, 15.4 parts of methyl methacrylate, 2.9 parts of n-butyl acrylate, 5.9 parts of hydroxyethyl acrylate, 5.1 parts of methacrylic acid and 0.5 part of Newcol 562SF are mixed and stirred. Thus, a monomer emulsion 2 was obtained.

Manufacture of thermosetting water-based paint (water-based topcoat base coat)

To 20 parts of oligomer 1 obtained in Production Example 1, 43.8 parts of Cymel 325 (manufactured by Nippon Cytec Industries, Ltd., methyl / butyl mixed etherified melamine resin, solid content 80%) and water obtained in Production Example 8 were stirred. 178.6 parts of dispersible acrylic polymer particles 1 (solid content 25.2%) were added. Thereafter, an aluminum paste GX180A (aluminum flake paste, manufactured by Asahi Kasei Co., Ltd.) in an amount of 20 parts as an aluminum pigment is added with mixing and dispersed, and further dimethylethanolamine and deionized water are added to adjust the pH to 8. 0, Ford Cup No. The viscosity was 40 seconds at 20 ° C. as measured by 4 to obtain an aqueous topcoat base coat paint 1.

  In Example 1, except that the oligomer 1 was changed to the oligomer 2 obtained in Production Example 2, adjustment was made in the same manner as in Example 1 to obtain an aqueous topcoat base coat paint 2.

  In Example 1, except that the oligomer 1 was changed to the polyester resin 1 obtained in Production Example 3, adjustment was made in the same manner as in Example 1 to obtain an aqueous topcoat base coating material 3.

  In Example 1, except that the oligomer 1 was changed to the polyester resin 2 obtained in Production Example 4, adjustment was made in the same manner as in Example 1 to obtain an aqueous topcoat base coating material 4.

  A water-based topcoat base coating material 5 was obtained in the same manner as in Example 1 except that the polyester resin 3 obtained in Production Example 5 was used as the oligomer 1 in Example 1.

  In Example 2, the amount of Cymel 325 was changed from 43.8 parts to 31.3 parts, and Superflex 410 (trade name, aqueous polycarbonate urethane resin solution, solid content 40 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) %) An aqueous topcoat base coat paint 6 was obtained in the same manner as in Example 2 except that 25 parts were added.

  In Example 2, the amount of oligomer 2 was changed from 20 parts to 10 parts, and an aqueous topcoat base coat paint 7 was obtained in the same manner as in Example 2 except that 25 parts of Superflex 410 was added.

In Example 2, the amount of oligomer 2 was changed from 20 parts to 10 parts, the amount of Cymel 325 was changed from 43.8 parts to 31.3 parts, and the blocked polyisocyanate cured obtained in Production Example 7 was further obtained. An aqueous topcoat base coat paint 8 was obtained in the same manner as in Example 2 except that 12.5 parts of the agent solution 1 (solid content 80%) and 25 parts of Superflex 410 were added.
(Comparative Example 1)
In Example 1, an aqueous topcoat base coating material 9 was obtained in the same manner as in Example 1 except that the polyester resin 4 obtained in Production Example 6 was used instead of the oligomer 1.

Coating film formation method (test plate production 1)
About the water-based topcoat basecoat paints 1-9 obtained in Examples 1-8 and Comparative Example 1, test plates were prepared as follows.
(Coating)
Electron 9600 (trade name, thermosetting epoxy resin-based cationic electrodeposition paint manufactured by Kansai Paint Co., Ltd.) on a 0.8 mm-thick dull steel sheet subjected to zinc phosphate conversion treatment so that the film thickness becomes 20 μm. Electrodeposition coating, heating at 170 ° C. for 30 minutes to cure, and then amylak TP-65-2 (trade name, polyester melamine resin-based automotive intermediate coating) manufactured by Kansai Paint Co., Ltd. to a film thickness of 35 μm Then, it was air-sprayed and heat-cured at 140 ° C. for 30 minutes to obtain an article to be coated.

Using the rotary electrostatic coating machine, the water-based topcoat base coating material 1 produced in Example 1 above was discharged on the object to be coated at a discharge rate of 300 cc, a rotational speed of 25,000 rpm, a shaping air pressure of 1.5 kg / cm ² , and a gun distance. The coating was applied at 30 cm, a conveyor speed of 5 m / min, a booth temperature and humidity of 25 ° C./75%, and a film thickness of 15 μm. Next, Magiclon TC-71 (trade name, acrylic / melamine resin solvent-type clear paint) manufactured by Kansai Paint Co., Ltd. was applied to the uncured base coat surface of Ford Cup #No. 4 was used to add Swazol 1000 (manufactured by Cosmo Oil Co., Ltd., petroleum aromatic hydrocarbon solvent) to adjust the viscosity to 30 seconds at a coating temperature of 20 ° C., and using a minibell rotary electrostatic coating machine, Painted to a film thickness of 40μm at a discharge rate of 200cc, a rotational speed of 40,000rpm, a shaping air pressure of 1kg / cm ² , a gun distance of 30cm, a conveyor speed of 4.2m / min, a booth temperature and humidity of 25 ° C / 75%. After leaving for 7 minutes, the test plate was produced by heating at 140 ° C. for 30 minutes to cure both coating films simultaneously.

The aqueous topcoat basecoat paints 2 to 9 were also coated in the same manner as the aqueous topcoat basecoat paint 1 to prepare test plates.
Performance test result 1
Table 1 shows the performance test results of the test plates and the water-based topcoat base coating materials 1 to 9 formed as described above. Test methods and evaluation methods are as follows.

Smoothness of coating film: The appearance of the test plate was visually evaluated.
○: Smoothness, gloss, and sharpness are all good △: Smoothness, gloss, and sharpness are slightly inferior ×: Any of smoothness, gloss, and sharpness is remarkably inferior IV value : Value of IV measured using a laser-type metallic feeling measuring apparatus (Alcorp LMR-200 (manufactured by Kansai Paint)). IV is the whiteness of the metallic coating film, and the more the metallic pigment is uniformly oriented in parallel to the coating surface, the more white it is, the better the metallic feel, and the higher the IV value, the more white it is.

  Metallic unevenness: The degree of metallic unevenness of the test plate was visually evaluated. ○: Metallic unevenness is not recognized, Δ: Metallic unevenness is slightly recognized, ×: Metallic unevenness is largely recognized.

  Paint solid content: About 2 g of the paint obtained in Examples 1 to 8 and Comparative Example 1 was sampled in an aluminum foil cup having a diameter of about 5 cm, and the solid content weight concentration (%) was measured (solid content measurement condition: Measurement after drying at 110 ° C. for 1 hour).

Coating film formation method (test plate preparation 2)
For the aqueous topcoat base coat obtained in Example 2 and Comparative Example 1, two types of test plates were prepared according to the description of Example 9 and Comparative Example 2 below.
(Coating material) The thickness of ELECRON 9600 (manufactured by Kansai Paint Co., Ltd., trade name, thermosetting epoxy resin-based cationic electrodeposition coating) on a 0.8 mm-thick dull steel plate subjected to zinc phosphate chemical conversion treatment An object to be coated was formed by electrodeposition coating so as to have a thickness of 20 μm and heating at 170 ° C. for 30 minutes to form an electrodeposition coating film.

WP-300T (polyester resin / polyisocyanate curing agent aqueous intermediate coating, manufactured by Kansai Paint Co., Ltd.) was applied on the object to be coated to a thickness of 35 μm. After standing for 2 minutes and preheating at 80 ° C. for 5 minutes, the water-based topcoat base coating 2 produced in Example 2 was applied to the uncured intermediate coating surface on the uncured intermediate coating surface using a rotary electrostatic coating machine. , Rotation speed 25,000rpm, shaping air pressure 1.5kg / cm ² , gun distance 30cm, conveyor speed 5m / min, booth temperature and humidity 25 ° C / 75%, painted to a film thickness of 15μm, 2 minutes After standing, preheating was performed at 80 ° C. for 3 minutes.
Next, Magiclon TC-71 (trade name, acrylic / melamine resin solvent-type clear clear coating manufactured by Kansai Paint Co., Ltd.) was applied to the uncured base coat surface of Ford Cup #No. 4 is used to adjust the viscosity to 30 seconds at a paint temperature of 20 ° C. with the addition of Swazol 1000, using a minibell-type rotary electrostatic coating machine, with a discharge amount of 200 cc, a rotational speed of 40,000 rpm, and a shaping air pressure 1kg / cm ² , gun distance 30cm, conveyor speed 4.2m / min, booth temperature and humidity 25 ° C / 75%, coated to a film thickness of 40µm, left for 7 minutes, then heated at 140 ° C for 30 minutes A test plate was prepared by simultaneously curing the three-layer coating film.
(Comparative Example 2)
A test plate was prepared in the same manner as in Example 9 except that the aqueous topcoat basecoat paint 2 in Example 9 was changed to the aqueous topcoat basecoat paint 9 obtained in Comparative Example 1.
Performance test result 2
The performance test results of the two test plates produced as described above are shown in Table 2. The test method and the evaluation method were tested and evaluated in the same manner as the method shown in the performance test result 1.

Claims (9)

(A) Oligomer (A-1) and / or polyester resin (A-2), (B) a crosslinking agent and (C) water-dispersible polymer particles,
The component (A-1) is obtained by reacting a compound (a-1) having 3 or more carboxyl groups in one molecule with a monoepoxide compound (a-2) having a long-chain hydrocarbon group 30 An oligomer having a hydroxyl value in the range of ~ 300 mgKOH / g, an acid value in the range of 20-220 mgKOH / g and a number average molecular weight in the range of 300-2000,
The component (A-2) further reacts with the component (A-1) with a polyvalent carboxylic acid and / or a polyvalent carboxylic acid anhydride (a-3) and / or a polyisocyanate compound (a-4). A polyester resin having a hydroxyl value in the range of 10 to 200 mg KOH / g, an acid value in the range of 10 to 100 mg KOH / g, and a number average molecular weight in the range of 400 to 6000, obtained by heating. Curable water-based paint. The component (a-3) in the component (A-2) is trimellitic anhydride, ethylene glycol bis (anhydrotrimellitate), 1,3-propanediol bis (anhydrotrimellitate) and pyromellitic anhydride The thermosetting water-based paint according to claim 1, which is at least one compound selected from the group consisting of: The thermosetting water-based paint according to claim 1 or 2, wherein the crosslinking agent (B) is a melamine resin and / or a block polyisocyanate compound. As water-dispersible polymer particles (C), water-dispersible acrylic polymer particles (C-1) having an acid value in the range of 1 to 100 mgKOH / g and a hydroxyl value in the range of 1 to 100 mgKOH / g are contained. The thermosetting water-based paint according to any one of claims 1 to 3. Based on 100 parts by weight of resin solid content in the thermosetting water-based paint, 5 to 50 parts by weight of component (A), 5 to 60 parts by weight of component (B), and 5 to 5 parts of component (C) as solids. The thermosetting water-based paint according to any one of claims 1 to 4, comprising 80 parts by weight. The thermosetting water-based paint according to any one of claims 1 to 5 is applied as a base coat paint to an object to be coated, and further a clear coat paint is applied onto the uncured base coat coated surface to thereby form a base coat and a clear coat. A method for forming a multilayer coating film, wherein the coating is simultaneously heated and cured. An intermediate coating is applied to an object to be coated, and the thermosetting water-based paint according to any one of claims 1 to 5 is applied as a base coat on the uncured intermediate coating surface. A method for forming a multilayer coating film, comprising: applying a clear coat paint on a cured base coat coating surface, and simultaneously heating and curing three layers of the intermediate coat, base coat and clear coat. 8. The clear coat paint is an acrylic resin / melamine resin system, an acrylic resin / polyisocyanate curing agent system, an acrylic resin / block polyisocyanate curing agent system, or an acid group-containing resin / epoxy group-containing resin system paint. A method for forming a multilayer coating film. The article | item formed by the method of any one of Claims 6-8.