JPH08165452A - Top coating compound composition and method for forming coating film - Google Patents

Abstract

PURPOSE: To obtain the subject composition having both chipping resistance and wear resistance, comprising plural lactone-modified OH-containing polyester resins having different amounts of lactone, a cross-linking agent and a specific onium salt. CONSTITUTION: This compound comprises (A) two kinds of lactone-modified hydroxyl group-containing polyester resins having 5-25wt.% of total lactone amount based on the polyester resin solid content and different amounts of lactone, (B) a cross-linking agent (e.g. an amino resin) and (C) an onium salt [preferably N-(4-methoxybenzyl)-N,N-dimethylanilinium-4- dodecylbenzenesulfonate] of a (non)cyclic ammonium cation in which a benzyl group of the formula (R1 to R3 are each H, nitro, etc.; R4 and R5 are each H, phenyl, etc.) is bonded to an N atom or a (non)cyclic sulfonium cation in which the group is bonded to an S atom and AsF6 <-> , SbF6 <-> , BF4 <-> , PF6 <-> , ClO4 <-> , FeCl4 <-> , CF3 SO3 <-> , an aromatic or an aliphatic sulfonate ion or an aromatic or aliphatic carboxylate ion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a top coating composition and a coating forming method, and more particularly to a top coating composition having improved chipping resistance, scratch resistance and abrasion resistance and a coating forming method.

[0002]

2. Description of the Related Art In recent years, demands for scratch resistance, abrasion resistance and chipping resistance have been particularly increased for top coatings for automobile bodies. Here, the scratch resistance refers to the scratch resistance due to the conventional brushing of the hair or the brush of the recent automatic car wash machine, and the abrasion resistance is, for example, the coating film around the driver's seat of the truck, Wear resistance due to friction with work clothes when the driver gets on and off. On the other hand, chipping resistance means that the coating film is sand (pebbles) on the road (chipping).
The ability to prevent rust from spreading and resulting in a poor appearance without damaging the base metal.

Conventionally, alkyd resin-based top coatings and acrylic resin-based top coatings have been used, but these are inferior in scratch resistance and abrasion resistance.

Therefore, in the "overcoat coating composition" of JP-A-60-67515, in order to make the coating film more elastic and to obtain the abrasion resistance of the coating film, (A) Scratch resistance is required. An acrylic resin copolymerizing a ε-caprolactone-modified vinyl monomer, which exhibits a remarkable effect, and (B) an unsaturated alicyclic polybasic acid of a certain amount or more as an acid component, and exhibits excellent compatibility with this acrylic resin. A top coating composition comprising a relatively linear oil-free polyester resin and (C) a cross-linking agent has been proposed.

However, in the above-mentioned top coating composition,
Although it is possible to prevent scratch resistance and abrasion resistance, it has a drawback that it is poor in softness and inferior in chipping resistance because it is a coating film mainly composed of an acrylic resin.

Therefore, a coating composition having improved chipping resistance has been proposed in "Paint Composition" of JP-A-59-45359. That is, this coating composition,
(A) Polyester resin of a mixture of lactone-modified polyester (I) having 6 to 8 ring carbons and lactone-unmodified polyester (II), (B) crosslinking agent, (C) pigment, (D) other And a lactone-modified polyester (I) in the component (A), a tough coating film having a high elongation can be formed. As a result, the chipping impact force can be absorbed, and the chipping resistance is improved.

Further, in Japanese Patent Laid-Open No. 5-253537, "Metallic coating method", an onium salt is used as a curing catalyst for simultaneously curing a base coat containing a metallic pigment and a clear top coat made of a low molecular weight resin. It is described to be used.

[0008]

However, since the coating composition of JP-A-59-45359 described above forms a soft coating film with the lactone-modified polyester (I), the coating film has a slight hardness. And was slightly inferior in abrasion resistance.

Further, the onium salt used in the metallic coating method disclosed in JP-A-5-253537 is used for simultaneously curing the base coat and the clear top coat, and the onium salt is excellent in chipping resistance and abrasion resistance. There is no mention of whether or not the contribution was made.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a top coating composition and a method for forming a coating film which have both chipping resistance and abrasion resistance. .

[0011]

In order to achieve the above object, the present invention according to claim 1 provides (A) a total lactone amount of 5 to 25% by weight per solid content of polyester resin and at least different lactone amounts. Two lactone-modified hydroxyl group-containing polyester resins, (B) a cross-linking agent, and (C) an acyclic or cyclic ammonium cation in which a benzyl group of the formula (I) represented by the following chemical formula 1 is bonded to a nitrogen atom, or and acyclic or cyclic sulfonium cation benzyl group is bonded to a sulfur _{^{atom, AsF 6 -, SbF 6 -}} , B
F ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , FeCl ₄ ⁻ , CF ₃
SO ₃ ^-, an aromatic or aliphatic sulfonic acid ion or an aromatic or aliphatic carboxylic acid ion, an onium salt,

Embedded image Is a top coating composition containing.

The invention according to claim 2 is characterized in that (A) at least two lactone-modified hydroxyl group-containing polyester resins having a total lactone amount of 5 to 25% by weight per solid content of the polyester resin and different lactone amounts; ) A cross-linking agent,
(C) an acyclic or cyclic ammonium cation in which the benzyl group of the formula (I) shown in the following chemical formula 2 is bonded to a nitrogen atom, or an acyclic or cyclic sulfonium cation in which the benzyl group is bonded to a sulfur atom. , AsF ₆ ^-, SbF _{6
^{-, BF 4 -, PF 6}} -, ClO 4 -, FeCl 4 -,
An onium salt of CF ₃ SO ₃ ⁻ , an aromatic or aliphatic sulfonate ion or an aromatic or aliphatic carboxylate ion,

[Chemical 4] A topcoat coating composition containing (a) an undercoat coating film,
(B) electrodeposition coating film, (c) intermediate coating film formed on the electrodeposition coating film, (d) chipping primer coating film formed on the electrodeposition coating film, (e) on the electrodeposition coating film A sequentially formed tipping primer coating film, an intermediate coating film, (f) an intermediate coating film sequentially formed on an electrodeposition coating film, a chipping primer coating film, (g)
At least one coating film of a substrate to be coated or a coating film forming method of coating on a substrate to be coated.

(A) Lactone-modified hydroxyl group-containing polyester
Resin The lactone-modified hydroxyl group-containing polyester resin used in the present invention is a polyester resin in which the total lactone amount in the polyester resin is 5 to 25% by weight, and the lactone amount (modification degree) is at least two. It has the above hydroxyl groups. Generally, a lactone-modified hydroxyl group-containing polyester resin is usually obtained by polycondensing a polyhydric alcohol with a polybasic acid or an anhydride thereof (by an ester reaction), adding a required amount of lactone to the polyester resin, and heating the polyester resin. can get. The lactone component is incorporated into the polyester resin by ring opening of the lactone and reaction with the hydroxyl group of the polyester resin.

As the polyhydric alcohol, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol,
Polypropylene glycol, neopentyl glycol,
1,2-butanediol, 1,3-butanediol,
2,3-butanediol, 1,4-butanediol,
1,5-pentanediol, 1,6-pentanediol, hydrogenated bisphenol A, hydroxyalkylated bisphenol A, 1,4-cyclohexanedimethanol,
2,2-dimethyl-3-hydroxypropyl-2,2-
Dimethyl-3-hydroxypropionate, 2,2,4
-Trimethyl-1,3-pentanediol, N, N-bis- (2-hydroxyethyl) dimethylhydantone, polytetramethylene ether glycol, polycaprolactone polyol, glycerin, sorbitol, trimethylolethane, trimethylolpropane, trimethylol Examples thereof include butane, hexanetriol, pentaerythritol, dipentaerythritol, tris- (hydroxyethyl) isocyanate, hydroxypivaleic acid neopentyl glycol ester and the like. Further, two or more of the above polyhydric alcohols can be used in combination.

As the polybasic acid or its anhydride, phthalic acid, phthalic anhydride, tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, methyltetrahydrophthalic acid, methyltetrahydrophthalic anhydride, Hymic acid anhydride, trimellitic acid, trimellitic acid anhydride, pyromellitic acid, pyromellitic acid anhydride, isophthalic acid, terephthalic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, adipic acid, azelaic acid, sebacic acid, succinic acid Examples thereof include acid, succinic anhydride, lactic acid, dodecenyl succinic acid, dodecenyl succinic anhydride, cyclohexane-1,4-dicarboxylic acid, and endo acid anhydride. Also, two or more of these may be used in combination.

The hydroxyl group-containing polyester resin used in the present invention has a molar ratio of the hydroxyl group of the polyhydric alcohol and the carboxyl group of the polybasic acid or its anhydride of 1.2 to.
It is obtained by reacting so as to be 1.8, and has two or more residual hydroxyl groups in one molecule as described above.

The lactone used for modification is a compound represented by the following chemical formula 5, specifically, ε-caprolactone,
ζ-enanthlactone, η-caprylolactone and derivatives thereof can be used. Preferred is ε-caprolactone.

[0018]

Embedded image In the present invention, the total amount of lactone per solid content of polyester resin is 5 to 25% by weight, and at least two kinds of polyester resins having different lactone amount (modification degree) are used. When the total amount of lactone is less than 5% by weight, the softness of the topcoat film is insufficient and chipping resistance is insufficient, and when it exceeds 25% by weight, the hardness of the topcoat film is insufficient and abrasion resistance is obtained. I can't. It is preferably 10 to 20% by weight. Further, the difference in the lactone amount of at least two lactone-modified hydroxyl group-containing polyester resins is preferably 5 to 25% by weight, and more preferably the difference in the lactone amount is 7 to 20% by weight.
Is. When the difference in the lactone amount between the two lactone-modified hydroxyl group-containing polyester resins is within the above range, chipping resistance and abrasion resistance can be obtained.

Further, the at least two lactone-modified hydroxyl group-containing polyester resins include a low-modification polyester resin having a lactone amount of 5 to 10% by weight per resin solid content and a lactone amount of 10 to 30% by weight per resin solid content. It is preferable that the high modified polyester resin is
The amount of lactone indicates the amount of lactone used for resin synthesis.

The lactone-modified hydroxyl group-containing polyester resin has a solid content weight ratio of the above [low-modification polyester resin / high-modification polyester resin] of 80 to 20/20.
˜80, more preferably 50 to 2
It is 0 / 50-80. The solid content weight ratio of the above [low modified polyester resin / high modified polyester resin] is 80.
When it exceeds / 20, the softness of the top coating film becomes insufficient and the chipping resistance becomes insufficient. On the other hand, when the solid content weight ratio of the above [low modified polyester resin / high modified polyester resin] is less than 20/80, the hardness of the top coating film becomes insufficient and abrasion resistance cannot be obtained.

Further, the number average molecular weight of each lactone-modified hydroxyl group-containing polyester resin is preferably 800 to 4000, more preferably the number average molecular weight is 100.
It is 0 to 2500. When the number average molecular weight of the lactone-modified hydroxyl group-containing polyester resin is less than 800, the cross-linking of the top coating film is insufficient, resulting in insufficient flexibility and chipping resistance. On the other hand, when the number average molecular weight of the lactone-modified hydroxyl group-containing polyester resin exceeds 4000, the resin viscosity increases, making thick film coating difficult.

Here, the number average molecular weight is a value measured by gel permeation chromatography in terms of polystyrene.

The hydroxyl value of each lactone-modified hydroxyl group-containing polyester resin is 50 to 200 mgKOH /
g is preferred, more preferably 80-150 mg KOH
/ G. When the hydroxyl value of the lactone-modified hydroxyl group-containing polyester resin is less than 50 mgKOH / g, the cross-linking point of the resin is insufficient, and the chipping resistance of the top coating film becomes insufficient. On the other hand, when the hydroxyl value of the lactone-modified hydroxyl group-containing polyester resin exceeds 200 mgKOH / g, the water resistance becomes poor due to unreacted hydroxyl groups (-OH groups) in the resin.

The acid value of each lactone-modified hydroxyl group-containing polyester resin is preferably 2 to 30 mgKOH / g, more preferably 5 to 20 mgKOH / g.
Acid value of lactone-modified hydroxyl group-containing polyester resin is 2m
If it is less than gKOH / g, the reactivity with the cross-linking agent becomes weak and the abrasion resistance deteriorates. On the other hand, when the acid value of the lactone-modified hydroxyl group-containing polyester resin exceeds 30 mgKOH / g, there are many carboxyl groups (—COOH groups),
Water resistance becomes poor.

Further, the hydroxyl group-containing polyester resin used in the present invention is a fat or oil such as castor oil, dehydrated castor oil, coconut oil, corn oil, cottonseed oil, linseed oil, rapeseed oil, poppy oil, safflower oil, soybean oil and tung oil. Alternatively, a hydroxyl group-containing polyester resin modified with a fatty acid extracted from these oils and fats can be used. In addition, "Curula E" (manufactured by Shell Chemical)
The fatty acid-modified epoxy resin can also be used.

In the production of a hydroxyl group-containing polyester resin modified with a fatty acid, 100% by weight of the polyester resin is used.
In contrast, the total amount of the above-mentioned resin and / or fatty acid is 30
It is preferable to add up to about wt%.

(B) Crosslinking Agent The crosslinking agent used in the present invention is, for example, an amino resin, a polyisocyanate compound (ie, an isocyanate group-terminated urethane prepolymer), a block polyisocyanate compound, a mixture of an amino resin and a blocked polyisocyanate compound, Alternatively, a mixture of a polyisocyanate compound and a blocked polyisocyanate compound may be used.

Here, the amino resin is, for example, one of amino compounds such as melamine, urea and benzoguanamine.
Examples of the condensate obtained by reacting one kind or a mixture of two or more kinds with formaldehyde, an ether compound obtained by reacting it with a lower alcohol such as methanol and butanol, and preferably an alkyl etherified melamine resin having a number average molecular weight of 400 to 1200 are mentioned. To be

Further, as the isocyanate group-terminated urethane prepolymer, fatty acid and / or aliphatic polyisocyanate such as tolylene diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, isophorodiisocyanate, glycerin, trimethylol propane, penta The thing added to the hydroxyl group of polyhydric alcohols, such as erythritol, is mentioned.

The blocked polyisocyanate compound is a polyisocyanate obtained by buolocking the isocyanate group of the addition polyisocyanate with a blocking agent such as phenol, oxime or methanol.

Further, the amount of the crosslinking agent added in the top coating composition and the coating film forming method of the present invention is such that the solid content weight ratio of the lactone-modified hydroxyl group-containing polyester resin and the crosslinking agent is 50.
It is preferably -80 / 50-20, more preferably 60-75 / 40-25. The solid content weight ratio of the lactone-modified hydroxyl group-containing polyester resin and the crosslinking agent is 5
When it is less than 0/50, the top coating film is too hard and the chipping resistance is poor. On the other hand, when the solid content weight ratio of the lactone-modified hydroxyl group-containing polyester resin and the cross-linking agent exceeds 80/20, the water resistance of the top coating film becomes poor.

When the cross-linking agent is a blocked polyisocyanate compound and an amino resin, the weight ratio of solids is 5 to 5.
It is preferably 50/95 to 50, more preferably 10 to 40/90 to 60. When the weight ratio of the solid content of the block polyisocyanate compound and the amino resin is within the above range, the acid resistance of the coating film can be obtained.

(C) Onium Salt In the present invention, the onium salt described below is used as a catalyst for the crosslinking reaction. The cation of this onium salt is an ammonium or sulfonium ion without a hydrogen atom having a benzyl group of formula (I) bonded to a nitrogen atom or a sulfur atom.

[0034]

[Chemical 6] Here, the remaining bonds bonded to the nitrogen atom or sulfur atom excluding the benzyl group may be bonded to independent hydrocarbon groups to form an acyclic onium ion,
A carbon atom bonded to a plurality of bonds may form a nitrogen-containing or sulfur-containing heterocyclic onium ion together with a nitrogen atom or a sulfur atom.

The onium ion in which the remaining bonds are bound to independent hydrocarbon groups corresponds to tertiary amines or thioethers. Examples of the nitrogen-containing heterocyclic ring which can form a plurality of remaining bonds include a pyridine ring, a 1,3-oxazolidine ring, an indole ring, a thiazole ring, a pyrrole ring, a quinoline ring, an isoquinoline ring, and a sulfur-containing heterocyclic ring. Examples of are thiophene ring, 1,4-oxathiane ring, thiane ring, 1,3
-Such as the dithian ring.

The anion of the onium salt, AsF ₆ ^-, S
^{_{bF 6 -, BF 4 -,}} PF 6 -, ClO 4 -, FeCl
^{_{4 -, CF 3 SO 3 -}} , an aromatic sulfonic acid ion, an aliphatic carboxylate ion, an aliphatic sulfonate ion or an aliphatic sulfonic acid ion. Examples of these onium salts include sulfonium salts represented by Chemical Formula 7 described in JP-A-58-37003, "Thermosetting Composition", JP-A-5-58.
No. 8-37004, “Thermosetting composition”, sulfonium salt shown in Chemical formula 8; JP-A No. 1-96169, “Novel benzylpyridinium salt”, the benzylpyridinium salt shown in Chemical formula 9; The benzylpyridinium salt shown in Chemical formula 10 described in "Novel benzylpyridinium salt" of JP-A 1-299270, and the chemical formula 11 described in "Novel heterocyclic ammonium salt" of JP-A-3-56470
Heterocyclic ammonium salt shown in JP-A-3-11526
No. 2, “α, α-disubstituted benzylpyridinium salts”
[Alpha], [alpha] -disubstituted benzylpyridinium salt shown in Chemical formula 12 described in JP-A-3-255261, benzylpyridinium sulfonate shown in Chemical formula 13 described in "Novel benzylpyridinium salt" in JP-A-3-20261, JP-A-2-255646. "Novel benzylammonium salt" described in Chemical formula 14, Benzylammonium sulfonate shown in Chemical formula 15 described in "Novel benzylammonium sulfonate" in JP-A-3-7249, JP-A No. 3-7249
"Novel benzyl ammonium salt" of JP-A 11044
The benzylammonium salt shown in Chemical formula 16 and the like is known.

[0037]

[Chemical 7]

Embedded image

[Chemical 9]

[Chemical 10]

[Chemical 11]

[Chemical 12]

[Chemical 13]

Embedded image

[Chemical 15]

Embedded image Typical of those specific compounds include: First, as the sulfonium salt, ethyl-benzyl-butylsulfonium hexafluorophosphate, 4-methylbenzyl-tetrahydrothiophenium hexafluoroantimonate, 3-chlorobenzyl-tetrahydrothiophenium-4-dodecylbenzenesulfonate, 3- Methylbenzyl-tetrahydrothiophenium stearate benzyl-1,4-oxathianium benzoate, α-methylbenzyl-3-oxotetrafodrothiophenium hexafluoroanthmonate, 4-
Examples thereof include nitrobenzyl-4-oxothianium tetrafluoroborate and 4-t-butylbenzyl-1,3-dithianium-4-dodecylbenzenesulfonate.

Further, as the benzylpyridinium salt,
N- (2-methylbenzyl) -4-cyanopyridinium hexafluorophosphate, N- (α, α-dimethylbenzyl) pyridinium trifluoromethanesulfonate, N- (2,4-dichlorobenzyl) -3-methylpyridinium perchlorate , N- (α-methylbenzyl) -2-chloropyridinium-p-toluenesulfonate, N- (2-chloro-6-fluorobenzyl) -4
-Carbamoylpyridinium hexafluoroantimonate, N- (4-methoxybenzyl) -2-chloropyridinium-4-dodecylbenzenesulfonate, N-
(2,6-dichlorobenzyl) -4-cyanopyridinium-p-toluene sulfonate, N- (α, α-dimethoxybenzyl) pyridinium naphthalene sulfonate and the like can be mentioned.

As the anilinium salt, N- (4
-Chlorobenzyl) -N, N-dimethoranilinium-
4-dodecylbenzenesulfonate, N- (4-methoxybenzyl) -N, N-dimethylanilinium stearate, N- (4-methoxybenzyl) -N, N-dimethylanilinium-4-dodecylbenzenesulfonate,
N- (methoxybenzyl) -N, N-dimethylanilinium-p-toluenesulfonate, N- (3-methylbenzyl) -N-ethyl-N-methylanilinium hexafluorophosphate, N- (2,6- Dichlorobenzyl) -N, N-dimethyl-N-p-triammonium tetrafluoroborate, N- (α-methylbenzyl)
-N, N-dimethyl-Nm-tolylammonium acetate, N- (4-nitrobenzyl) -N, N-diethylanilinium hexafluoroarseneto, N- (2-methylbenzyl) -N, N- Dimethylanilinium-4-
Dodecyl benzene sulfonate etc. are mentioned.

As the 1,3-oxazolidinium salt, 3,3-dimethyl-2-phenyl-1,3-oxazolidinium-p-toluenesulfonate, 3-methyl-3-benzyl-2 is used. -P-tolyl-1,3-oxazolidinium hexafluoroantimonate, 3-methyl 3- (4-methoxybenzyl) -2-t-butyl-1,
3-oxazolidinium tetrafluoroborate, 3,
3,4-trimethyl-2- (2-chlorophenyl)-
1,3-oxazolidinium laurate, 3,3-dimethyl-2-phenyl-1,3-oxazolidinium hexafluorophosphate, and the like can be mentioned.

As other cyclic ammonium, N-
(3-Methylbenzyl) -N-methylindolium hexafluorophosphate, N- (4-t-butylbenzyl) thiazolium-p-toluenesulfonate, N-
Methyl-N- (α-methylbenzyl) pyrazolium hexafluoroantimonate, N- (α, α-dimethylbenzyl) isoquinolinium perchlorate, N- (4-
(Chlorobenzyl) quinolinium laurate, 2-phenyl-3,3-dimethyloxazolidinium hexafluoroantimonate, 2- (4-nitrophenyl) -3,
Examples thereof include 3-dimethyloxazodilium hexafluoroantimonate, 2-phenyl-3,3-dimethyloxazolidinium hexafluoroantimonate, and the like.

As the onium salt, benzyl ammonium sulfonate represented by Chemical formula 17 or N- (4-methoxybenzyl) -N, N-dimethylanilinium-4-dodecylbenzene sulfonate is preferable.

[0043]

[Chemical 17] Further, the amount of the onium salt blended is [onium salt] / [lactone-modified hydroxyl group-containing polyester resin + solid content weight ratio +
Crosslinking agent] = 0.1 to 5/100 is preferable,
More preferably, the solid content weight ratio is 0.5 to 3/100.
Is. The solid weight ratio of [onium salt] / [lactone modified hydroxyl group-containing polyester resin + crosslinking agent] is 0.1 / 10.
When it is less than 0, the cross-linking ratio is insufficient and wear resistance becomes poor. On the other hand, when the solid weight ratio exceeds 5/100, it is excessively hardened and is easily damaged by chipping, resulting in poor appearance and corrosion resistance.

In addition to these components, the top coating composition of the present invention may optionally contain the following crosslinked polymer fine particles, pigments, solvents and additives within a range that does not impair the effects of the present invention. (D) Crosslinked polymer fine particles (microgel) Conventionally, various methods have been proposed for producing crosslinked polymer fine particles, one of which is crosslinking an ethylenically unsaturated monomer. To prepare a cross-linked polymer fine particle dispersion by suspension polymerization or emulsion polymerization in a water-based medium with a hydrophilic copolymerizable monomer,
Water is removed by solvent substitution, azeotropic distillation, centrifugation, drying, etc. to obtain crosslinked polymer fine particles. The other one dissolves the monomer like a low SP organic solvent such as an aliphatic hydrocarbon, The polymer is referred to as NAD method or precipitation method in which an ethylenically unsaturated monomer and a crosslinkable copolymer are copolymerized in a non-aqueous organic solvent and the obtained crosslinked polymer fine particle copolymer is dispersed. Is the method.

The crosslinked polymer fine particles used in the present invention may be produced by any of the above methods. You may use the manufacturing method of the crosslinked polymer fine particle which uses the water-soluble resin which has a zwitterionic group described in Unexamined-Japanese-Patent No. 58-129066 of this art. That is, the formula in the molecule (In the formula, R is a C ₁ -C ₆ alkylene or phenylene group which may have a substituent, Y is —COOH or —
SO ₃ H) is obtained by copolymerizing two or more kinds of α, β-ethylenically unsaturated group-containing monomers in the presence of a resin having a group represented by SO ₃ H) in an aqueous or non-aqueous organic medium. Crosslinked polymer fine particles. Its particle size is 0.01-10μ
m is preferable, and more preferably 0.05 to 1 μm. When the particle diameter of the crosslinked polymer fine particles is less than 0.01 μm,
The rheology control function of the composition is not exhibited by the addition of the crosslinked polymer fine particles, that is, shear stress is expressed during coating, and structural viscosity is expressed after coating to prevent sagging, dipping, blurring, etc. Absent. On the other hand, if the particle diameter of the crosslinked polymer fine particles exceeds 10 μm, the appearance becomes poor due to the generation of lumps.

Examples of the ethylenically unsaturated monomer and the crosslinkable copolymerizable monomer which can be used in the method for producing fine particles of crosslinked polymer are described in JP-A-62-79873 of the present applicant. . That is, as the ethylenically unsaturated monomer, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. Alkyl ester of acrylic acid or methacrylic acid and other monomers having an ethylenically unsaturated bond which can be copolymerized therewith, such as styrene, α-methylstyrene, vinyltoluene, t-butylstyrene, ethylene, propylene, Examples include vinyl acetate, vinyl propylene acrylate, acrylonitrile, methacrylonitrile, dimethylaminoethyl (meth) acrylate, and the like. Two or more of these monomers may be used.

The crosslinkable copolymerizable monomer is a monomer having two or more radically polymerizable ethylenically unsaturated bonds in the molecule and / or two kinds of ethylene each carrying a group capable of reacting with each other. Including a monomer containing a polyunsaturated group.

Examples of the monomer having two or more radically polymerizable ethylenically unsaturated groups in the molecule include a polyunsaturated polymerizable unsaturated monocarboxylic acid ester and a polybasic acid polymerizable unsaturated alcohol ester. , And aromatic compounds substituted with two or more vinyl groups.

Examples of the monomer having two kinds of ethylenically unsaturated groups each carrying a group capable of reacting with each other include epoxy group-containing ethylenically unsaturated monomers such as glycidyl acrylate and glycidyl methacrylate. , Acrylic acid, methacrylic acid, crotonic acid and the like are the most representative carboxyl group-containing ethylenically unsaturated monomers, but the mutually reactive groups are not limited to these, for example, amine and Various compounds such as carbonyl, epoxide and carboxylic acid anhydride, amine and carboxylic acid chloride, alkyleneimine and carbonyl, organoalkoxysilane and carboxyl, hydroxyl and isocyanato have been proposed, and the present invention broadly includes these. is there.

The crosslinked polymer fine particles produced in an aqueous medium or a non-aqueous organic medium can be used as they are, but the crosslinked polymer fine particles are isolated by a method such as filtration, spray drying or freeze drying and used as they are or in a mill. It can also be used after crushing to an appropriate particle size by using the above.

The amount of crosslinked polymer fine particles having an average particle diameter of 0.01 to 10 μm is [crosslinked polymer fine particles] / [lactone-modified hydroxyl group-containing polyester resin +] in terms of solid content weight ratio.
Crosslinking agent] = 1 to 20/100 is preferable, and the solid content weight ratio is more preferably 2 to 10/100. When the solid content weight ratio is less than 1/100, sagging particularly occurs and coating workability deteriorates. On the other hand, when the solid content weight ratio exceeds 20/100, the appearance of the coating composition becomes poor because the viscosity of the coating material increases and the surface becomes glossy.

(E) An aluminum foil having a pigment particle size of 10 to 45 μm, a bronze foil,
Tin foil, gold foil, silver foil, copper foil, titanium metal foil, stainless steel foil, nickel foil, chromium, cobalt sulfide, manganese sulfide, titanium sulfide, alloy foils of these, metal foil coated with plastic, foil-like phthalocyanine blue From metallic iron oxide pigments as a transparent pigment, inorganic iron oxides as transparent pigments such as Sicotrans Red L2915D, Sicotrans Yellow L1915 and 1916 (all manufactured by BASF) and organic chromophthal red A2B (manufactured by Ciba Geigy). Selected, or among the dyes, dark colors such as red, blue, purple, black, and brown, for example, Orazole Black RL, Orazole Red B, Orazole Yellow 3R (all manufactured by Ciba Geigy) Stuff, titanium dioxide, phthalocyanine blue, phthalocyanine green, quinacridone,
Coloring pigments such as indanthrone, isoindolinone, pericin, anthravirimidine, carbon black, benzimidazolone, yellow iron oxide, red iron oxide and the like can be mentioned. Here, the pigment is generally an achromatic or chromatic inorganic compound that is insoluble in water, a medium such as oil or a solvent, and an organic compound, and is composed of powder in a fine particle state, and is dyed to an object in the state as it is. It does not have the performance to do. However, it refers to a substance that adheres to an object with the aid of a vehicle (a color-developing agent) or is dispersed in an object and colored. On the other hand, a dye is an achromatic or chromatic organic compound that is generally soluble in water, a medium such as oil or a solvent, and the ability to dye and color an object by itself in a solution state or a dispersed state. Means what you have.

(F) When the solvent top coating composition is used as an organic solvent type coating,
Solvents such as aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as mineral spirit, esters such as ethyl acetate and butyl acetate, and ketones such as methyl ethyl ketone, alone or in combination (selected appropriately). Can be used. Further, the top coating composition of the present invention can be used not only as an organic solvent type coating composition but also as an aqueous coating composition. In this case, water or various hydrophilic organic solvents can be used as the solvent.

(G) Additives Examples of additives include curing catalysts such as dodecylbenzene sulfonic acid, benzotriazole-based ultraviolet absorbers,
Examples thereof include benzophenone-based antioxidants, surface modifiers such as silicone and organic polymers, anti-sagging agents, and thickeners. These components can usually improve the performance of paints and coating films in an amount of 5 parts by weight or less based on 100 parts by weight of [lactone-modified hydroxyl group-containing polyester resin + crosslinking agent].

Next, three examples of preferable formulations of the top coating composition according to the present invention and the top coating composition used in the coating film forming method of the present invention will be shown.

Formulation Example 1. The top coating composition comprises the following (A) to (D). That is, (A) (A-1): the amount of lactone is 5 to 10 per resin solid content.
(A-2): a lactone-modified hydroxyl group-containing polyester resin containing 10 to 30% by weight of lactone per resin solid content.
And a solid content weight ratio of (A-1) / (A-2) of 80 to 20/20 to 80, and a polyester resin solid. The total lactone amount per minute is 7 to 25% by weight, and the difference in the amount of lactone between (A-1) and (A-2) is 5 to 25% by weight.
The lactone-modified hydroxyl group-containing polyester resin is
0 to 80 parts by weight, (B) 20 to 50 parts by weight of a cross-linking agent which is any one of an amino resin, a polyisocyanate compound, a block polyisocyanate compound, or a mixture of an amino resin and a block polyisocyanate compound, (C) with respect to a total of 100 parts by weight of (A) and (B), (C) an acyclic or cyclic ammonium cation in which the benzyl group of the formula (I) shown below is bonded to a nitrogen atom, or the benzyl group An onium salt of an acyclic or cyclic sulfonium cation in which is bonded to a sulfur atom and an anion composed of an aromatic sulfonate ion is 0.1 to 5
Parts by weight,

Embedded image (D) 1 to 20 parts by weight of crosslinked heavy-weight fine particles having an average particle diameter of 0.01 to 10 μm, if necessary.

Formulation example 2. The top coating composition comprises the following (A) to (D). That is, (A) (A-1): the amount of lactone is 5 to 10 per resin solid content.
(A-2): a lactone-modified hydroxyl group-containing polyester resin containing 10 to 30% by weight of lactone per resin solid content.
% Of the lactone-modified hydroxyl group-containing polyester resin, and the solid content weight ratio of (A-1) / (A-2) is 50 to 20/50 to 80, and the polyester resin is solid. The total amount of lactone per minute is 10 to 20% by weight, and the difference in the amount of lactone between (A-1) and (A-2) is 7 to 20% by weight.
The lactone-modified hydroxyl group-containing polyester resin is
0 to 75 parts by weight, (B) 25 to 40 parts by weight of a cross-linking agent, which is either an amino resin, a polyisocyanate compound, a block polyisocyanate compound, or a mixture of an amino resin and a block polyisocyanate compound, (C) with respect to a total of 100 parts by weight of (A) and (B), (C) an acyclic or cyclic ammonium cation in which the benzyl group of formula (I) shown in Chemical formula 18 above is bonded to a nitrogen atom, or the benzyl group An onium salt of an acyclic or cyclic sulfonium cation in which is bonded to a sulfur atom and an anion composed of an aromatic sulfonate ion is 0.5 to 3
Parts by weight, (D) 2 to 10 parts by weight of crosslinked heavy-weight fine particles having an average particle diameter of 0.01 to 10 μm, if necessary.

Formulation example 3. The top coating composition comprises the following (A) to (G). That is, (A) (A-1): the amount of lactone is 5 to 10 per resin solid content.
(A-2): a lactone-modified hydroxyl group-containing polyester resin containing 10 to 30% by weight of lactone per resin solid content.
% Of the lactone-modified hydroxyl group-containing polyester resin, and the solid content weight ratio (A-1) / (A-2) is 80 to 20/20 to 80, and the solid polyester resin is solid. The total lactone amount per minute is 7 to 25% by weight, and the difference in the amount of lactone between (A-1) and (A-2) is 5 to 25% by weight.
The lactone-modified hydroxyl group-containing polyester resin is
0 to 80 parts by weight, (B) 20 to 50 parts by weight of the crosslinking agent, and (A)
And (B) with respect to 100 parts by weight in total, (C) an acyclic or cyclic ammonium cation in which the benzyl group of the above formula (I) is bonded to a nitrogen atom or a non-cyclic group in which the benzyl group is bonded to a sulfur atom. 0.1 to 5 parts by weight of an onium salt of a cyclic or cyclic sulfonium cation and an anion composed of an aromatic sulfonate ion, 0 to 10 parts by weight of (D) crosslinked heavy-weight fine particles, E) The pigment is 30 to 100 parts by weight, (F) the solvent is 50 to 200 parts by weight, and (G) the additive is 0 to 5 parts by weight.

Next, a method for producing the top coating composition of the present invention will be described.

Production Method The production method of the top coating composition of the present invention is not particularly limited,
Methods known to those skilled in the art can be used. For example, in the case of an enamel coating, a desired coating composition can be obtained by kneading and dispersing a mixture of pigments and the like using a kneader or a roll according to a conventional method. The solid content of the top coating composition according to the present invention is 30 at the time of production.
It is preferably in the range of ˜70% by weight and in the range of 10˜50% by weight at the time of coating.

Next, the coating method using the top coating composition of the present invention will be described.

Coating Method The top coating composition of the present invention is diluted with a solvent so as to have an appropriate viscosity and then coated by a method such as spraying or coating. The viscosity of the topcoat composition is measured by Ford Cup # 4. The viscosity of the spray coating composition is adjusted to 20-40 seconds / 20 ° C with Ford Cup # 4.

As the coating machine, an atomizing type coating machine is preferably used, and examples thereof include air spray, airless spray, and various electrostatic coating machines.

The base material to be coated, which is the base of the coating, is, if necessary,
It may be an undercoat, or an undercoat and an intermediate coat. Known undercoat paints and intermediate paints can be used. Further, by using a chipping primer as a binder coat together, a coating film having further improved chipping resistance can be obtained.

The dry film thickness of the coating film of the top coating composition of the present invention can be varied over a wide range depending on the desired application, but in many cases a useful film thickness of 20 to 80 μm is useful.

According to the coating method of the present invention, the coating film is cured after being coated on the substrate. The curing temperature is room temperature to 180 ° C, preferably 100 ° C to 160 ° C. If it is cured by (1), an effect coating film having a high degree of crosslinking can be obtained. Although the curing time varies depending on the curing temperature, etc., it is generally 1 at a temperature of 100 to 160 ° C.
It is suitable to cure for 0 to 30 minutes.

Further, according to the top coating composition of the present invention,
The crosslink density of the formed coating film is 4 × 10 ⁻³ mol / cc.
It is preferable that the dynamic Tg (Tg: glass transition temperature) is from 75 ° C. to 95 ° C. at −10 × 10 ⁻³ mol / cc. When the cross-linking density of the coating film is less than 4 × 10 ⁻³ mol / cc, the hardness of the top coating film is insufficient and abrasion resistance cannot be obtained. On the other hand, the crosslink density of the coating film is 10 × 10 ^-3 mol / c
When it exceeds c, the softness of the top coating film becomes insufficient and the chipping resistance becomes insufficient. Moreover, the dynamic Tg of the coating film is 75.
If the temperature is lower than 0 ° C, the hardness of the top coating film becomes insufficient and abrasion resistance cannot be obtained. On the other hand, when the dynamic Tg of the coating film exceeds 95 ° C., the softness of the top coating film becomes insufficient and the chipping resistance becomes insufficient.

Next, the method of forming a coating film by the top coating composition of the present invention will be described.

Coating Film Forming Method As shown in FIG. 1, (a) an undercoating film, (b) an electrodeposition coating film, and (c) an intermediate coating film formed on the electrodeposition coating film as shown in FIG. , (D) a tipping primer coating formed on the electrodeposition coating, (e) a tipping primer coating sequentially formed on the electrodeposition coating, an intermediate coating, (f) a coating on the electrodeposition coating Formed intermediate coating film, chipping primer coating film,
(G) At least one coating film of the substrate to be coated, or a coating film forming method of coating on the substrate to be coated.

Generally, in the case of a coating system for an automobile body,
First, a base treatment such as degreasing and chemical conversion treatment is performed, and then electrodeposition coating is performed. When performing electrodeposition coating on steel materials,
As the electrodeposition coating material, both cationic resin type and anionic resin type can be used.

The electrodeposition coating film applied to the steel material by electrodeposition coating is usually preferably provided so as to have a dry film thickness of 10 to 40 μm. Other conditions in the electrodeposition coating may be the same as those in the conventional electrodeposition coating process.

Further, the chipping primer coating film formation is
Any primer for chipping resistance can be used, and for example, a block polyisocyanate compound to which a polycaprolactone diol described in JP-A-6-41494 of the present applicant is bound and two or more hydroxyl groups in one molecule are contained. It is possible to preferably use a chipping-resistant coating composition or the like containing a resin as a main component. The dry film thickness of the chipping primer coating film is preferably 2 to 60 μm, more preferably 5 to 40 μm. In forming the intermediate coating film, an alkyd resin, polyester resin, or acrylic resin-based coating material can be used as the intermediate coating material. The coating can be performed by a usual method, for example, electrostatic coating. Baking can also be performed by a conventional method. The film thickness of the intermediate coating film is 20 to 60 μm as a dry film thickness.
It is preferably m.

Usually, the upper coating film is baked, but the wet-on-wet or dry-on-wet method can be applied partially or entirely.

The chipping primer coating film and the intermediate coating film are formed by the method shown in (c), (d), (e) and (f) of FIG.

[0075]

As shown in FIG. 2, generally, when the same resin is used to increase the crosslink density to improve the wear resistance, the dynamic Tg (also referred to as Tm) simultaneously rises as indicated by "○".
Problems occur in chipping resistance and appearance.

Therefore, according to the present invention, the top coating composition contains at least two lactone-modified hydroxyl groups in which the total lactone amount is 5 to 25% by weight based on the solid content of the polyester resin as the component (A) and the lactone amount is different. Since it contains polyester resin, it lowers the dynamic Tg of the main resin,
And the onium salt of the component (C) which is a curing catalyst,
The crosslink density of the coating film can be increased. Therefore, the crosslink density can be increased without increasing the dynamic Tg of the coating film (indicated by “●” in FIG. 2), and the chipping resistance and abrasion resistance can be improved. The preferred range of the present invention is the hatched portion in FIG.

According to the coating film forming method of the present invention, the above-mentioned top coating film having improved chipping resistance and abrasion resistance is applied onto (a) the under coating film and (b) electrodeposition coating. On the membrane,
(C) on the intermediate coating film formed on the electrodeposition coating film, (d) on the chipping primer coating film formed on the electrodeposition coating film,
(E) On the chipping primer coating, the intermediate coating, which are sequentially formed on the electrodeposition coating, (f) On the intermediate coating, the tipping primer coating, which are sequentially formed on the electrodeposition coating, (g) It can be formed on a coated substrate.

[0078]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples.

Synthesis Example 1. Polylactone containing lactone-modified hydroxyl group
Method for producing stell resin In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser with a dehydration trap, and a nitrogen gas introduction tube, 5 parts by weight of trimethylolpropane, 25 parts by weight of neopentyl glycol, hydroxypivaleic acid neopentyl glycol ester. Charge 10 parts by weight, 30 parts by weight of hexahydroxyphthalic anhydride, 20 parts by weight of isophthalic acid, 10 parts by weight of Cardura E (Shell Chemical: fatty acid modified epoxy resin), 0.02 part of dibutyltin oxide and 2 parts by weight of xylene for reflux. While stirring, the dehydration reaction was carried out under a nitrogen stream at a temperature of 230 ° C. until the acid value of the solid content reached 8 mgKOH / g. After cooling, it was diluted with 21 parts by weight of xylene, and then ε-
Charge 8 parts by weight of caprolactone to a reaction vessel, and keep at 150 ° C.
And the amount of unreacted ε-caprolactone was confirmed by IR (infrared absorption spectrum). When the reaction rate reached 98% or more, the reaction was terminated and cooled. After cooling, xylene was added to obtain a polyester resin solution A. This polyester resin solution A has NV = 70% and Mn = about 200
0, hydroxyl value of resin = 95. Table 1 shows the composition and characteristic values.

Synthesis Examples 2-8. Lactone modified hydroxyl group
Reester Resin Production Method Based on the resin composition shown in Table 1, lactone-modified hydroxyl group-containing polyester resin solutions B to H in which the modification amount of lactone is changed.
Was produced according to Synthesis Example 1. In the table, the unit of "lactone modified hydroxyl group-containing polyester resin" is "part by weight".

[0081]

[Table 1] Production Example 1. The lactone-modified hydroxyl group-containing polyester resin solutions A and C obtained in Synthesis Example 1 were used to prepare a solid content weight ratio of 1/1.
The pigment was dispersed according to the dispersion composition shown in Table 2 to prepare a dispersion paste. The obtained dispersion paste was dissolved according to the formulation shown in Table 3, and a solution of 1 part by weight of onium salt (C-1) and 1 part by weight of IPA (isopropyl alcohol) was added to prepare a paint, and this paint was used as "Solvesso 150". (Esso Chemical mixed solvent) 100 parts by weight, diluted with a mixed solvent consisting of 50 parts by weight of ethyl acetate, 23 seconds / Ford Cup # 4 (20
℃) was adjusted.

[0082]

[Table 2] Dispersion and distribution titanium dioxide: (P-1) 67 parts by weight Resin solution A / C = 1/1 (solid content weight ratio) 20 parts by weight (solid content) Solvesso # 150 13 parts by weight total 100 Parts by weight

[Table 3] Coating composition Dispersion paste 100 parts by weight (solid content) Resin solution A / C = 1/1 (solid content weight ratio) 47 parts by weight (solid content) Crosslinking agent: (H-1) 33 parts by weight Onium salt: (C-1) 1 part by weight Butanol 8 parts by weight Additive ^* 1 part by weight Total 190 parts by weight Production Examples 2-16 and Comparative Production Examples 1-5. According to the above Production Example 1, a paint was prepared with the composition shown in Table 4, Table 5 and Table 6 for pigment dispersion and dissolution, and diluted to an appropriate viscosity similar to Production Example 1,
Prepared. The units of “solid content” and “lactone content in polyester resin” in the table are “part by weight” and “% by weight”, respectively.

[0083]

[Table 4]

[Table 5]

[Table 6] The crosslinking agent is as follows.

H-1: Melamine resin; "U-Van 20N
“-60” (NV = 60%) Mitsui Toatsu Chemical Co., Ltd. onium salt is as follows.

C-1: N- (4-methoxybenzyl)-
N, N-Dimethylanilinium-4-dodecylbenzenesulfonate C-2: N- (2-methylbenzyl) -N, N-dimethylanilinium-4-dodecylbenzenesulfonate C-3: N- (4-chlorobenzyl) ) -N, N-Dimethylanilinium-4-dodecylbenzenesulfonate C-4: N- (4-methoxybenzyl) -N, N-dimethylanilinium-p-toluenesulfonate C-5: N- (4-methoxy) Benzyl) -2-chloropyridinium-4-dodecylbenzene sulfonate C-6: 3,3-dimethyl-2-phenyl-1,3-oxalidinium-p-toluenesulfonate P-1 of the pigment is titanium dioxide.

M-1 of the crosslinked polymer fine particles is AZS-7.
97 (manufactured by Nippon Paint Co., Ltd.) The additive of "*" is Modaflow (Surface conditioner: manufactured by Mitsubishi Monsanto). Also, abrasion resistance is ABRASION TESTER.
Using NUS-ISO-1 (manufactured by Suga Test Instruments Co., Ltd.),
The reduction amount of the coating film weight was measured after a wear test of Buller made of Büller with a load of 700 g and # 800 for 300 times. The dynamic Tg and crosslink density are Vibron DDV-II-E.
It was measured using A type (manufactured by Toyo Baldwin Co., Ltd.). Furthermore, the pencil hardness was measured according to JIS K5400.

Examples 1-35 and Comparative Examples 1-10. In the examples and comparative examples, a coating film was formed under the following processing conditions and evaluated by the following evaluation methods. The results are shown in Tables 7 and 8.

Coating film forming treatment conditions : Material: In the case of Examples 1 to 34 and Comparative Examples 1 to 10; after degreasing, 100 × 150 × 0.8 zinc phosphate conversion treatment was performed.
mm SPC-1 dull steel plate In the case of Example 35; 100 × 150 × 3 mm FRP panel Base coat: Electrodeposition coating (ED); “Power top U-60
0 "(manufactured by Nippon Paint Co., Ltd.), cationic electrodeposition paint precoat primer (PC); Superlac D1F
P (epoxy-based) (manufactured by Nippon Paint Co., Ltd.), epoxy-based precoat primer Intermediate coating: "Olga P-5" (manufactured by Nippon Paint Co., Ltd.),
Polyester / melamine resin-based paint "Olga CP-300" (manufactured by Nippon Paint Co., Ltd.), acrylic polyol / polycaprolactone diol-containing block isocyanate-based chipping primer Evaluation method : Visual appearance: The appearance of the coating film was visually evaluated.

3: Good (no tingling, blurring, and ash cast) 2: Normal (slightly tingling, blurring, and ash cast) 1: Poor (consisting of biting, blur, ash cast) Chipping resistance : Gravel meter (manufactured by Suga Test Instruments Co., Ltd.) with air pressure of 4 kg / cm ² and crushed stone No. 5
Using 0 g, the coating film state after the shot was evaluated at a distance of 35 cm, an angle of 45 ° and -20 ° C.

5: No peeling of coating film 4: Very slight peeling of coating film was observed 3: There was peeling of coating film of 1 mmφ or less 2: Peeling of coating film was noticeable 1: Peeling of coating film was noticeable

[Table 7]

[Table 8] From these results, according to the top coating composition and coating film formation of the present invention, the softening of the coating film by the two specific polyester resins and the increase in the crosslinking density by the specific onium salt and the specific resin / crosslinking agent Provides chipping resistance and abrasion resistance.

The top coating composition and coating film forming method of the present invention can be used for coating automobile bodies and parts, but is not limited to this application, and other various furniture,
It can be used as a housing for various devices, or as an interior material or exterior material of a house.

Further, another preferred embodiment of the present invention will be described below.

1. The difference in the amount of lactone between at least two lactone-modified hydroxyl group-containing polyester resins is 5 to 25
A top coating composition and a method for forming a coating film, which are in weight%.

2. (A-1) at least two or more lactone-modified hydroxyl group-containing polyester resins, wherein the lactone amount of the lactone-modified hydroxyl group-containing polyester resin is 5 to 10% by weight based on the resin solid content; A-2): The lactone amount of the lactone-modified hydroxyl group-containing polyester resin is 10 to 3 per resin solid content.
A topcoat coating composition and a coating film forming method comprising 0% by weight of a lactone-modified hydroxyl group-containing polyester resin.

3. A top coating composition and a method for forming a coating film, wherein the total amount of lactone per solid content of polyester resin is 10 to 20% by weight.

4. A top coating composition and a coating film forming method, wherein the lactone of the lactone-modified hydroxyl group-containing polyester resin is represented by the following chemical formula 19.

[0097]

[Chemical 19] 5. A topcoat coating composition and a coating film forming method, wherein the lactone of the lactone-modified hydroxyl group-containing polyester resin is polycaprolactone.

6. The (A-1) / (A-2) solid content weight ratio of the lactone-modified hydroxyl group-containing polyester resin is 80 to 20.
Top coating composition and coating film forming method of / 20 to 80.

7. The number average molecular weight of each lactone-modified hydroxyl group-containing polyester resin is 800 to 4000,
Hydroxyl value 50-200mgKOH / g, acid value 2-30m
A top coating composition having gKOH / g and a method for forming a coating film.

8. A top coating composition and a method for forming a coating film, wherein the crosslinking agent is an amino resin or a polyisocyanate compound.

9. A top coating composition and a coating film forming method, wherein the cross-linking agent is [block polyisocyanate compound] or [block polyisocyanate and amino resin].

10. The solid content weight ratio of the lactone-modified hydroxyl group-containing polyester resin and the crosslinking agent is 50 to 80/50.
The coating composition and the method for forming a coating film, wherein the coating composition is 20 to 20.

11. When the cross-linking agent is a blocked isocyanate and an amino resin, the solid content weight ratio of both is 5 to 5
The top coating composition and the coating film forming method, which are 0/95 to 50.

12. A top coating composition and a method for forming a coating film, wherein a cation in an onium salt is cyclic ammonium bonded to a nitrogen atom.

13. A topcoat coating composition and a method for forming a coating film, wherein the anion in the onium salt is an aromatic sulfonate ion.

14. A top coating composition and a method for forming a coating film, wherein the onium salt is the following chemical formula 20:

[0107]

Embedded image 15. The onium salt is N- (4-methoxybenzyl)-
A topcoat coating composition and a method for forming a coating film, which is N, N-dimethylanilinium-4-dodecylbenzenesulfonate.

16. The top coating composition and the coating film forming method, wherein the amount of the onium salt is [onium salt] / [lactone modified hydroxyl group-containing polyester resin + crosslinking agent] = 0.1 to 5/100 in terms of solid content weight ratio.

17. Furthermore, the average particle diameter is 0.01 to 10 μm.
Top coating composition containing the crosslinked polymer fine particles and a method for forming a coating film.

18. The blending amount of the crosslinked polymer fine particles having an average particle diameter of 0.01 to 10 μm is [crosslinked polymer fine particles] / [lactone-modified hydroxyl group-containing polyester resin + crosslinking agent] = 1 to 20/100 in terms of solid content weight ratio. Topcoat coating composition and coating film forming method.

19. (A) (A-1): A lactone-modified hydroxyl group-containing polyester resin having an amount of lactone of 5 to 10% by weight based on the resin solid content, and (A-2): an amount of lactone of 10 to 30% by weight based on the resin solid content. % Of the lactone-modified hydroxyl group-containing polyester resin, and (A-1) / (A
-2) has a solid content weight ratio of 80 to 20/20 to 80,
And the total amount of lactone per solid content of polyester resin is 7
50 to 80 parts by weight of a lactone-modified hydroxyl group-containing polyester resin having a lactone content of (A-1) / (A-2) of 5 to 20% by weight, and (B) an amino resin. A polyisocyanate compound, a block polyisocyanate compound, or a mixture of an amino resin and a blocked polyisocyanate compound in an amount of 20 to 50 parts by weight, (C) the onium salt of "13." 1 to 5 parts by weight, (D) 1 to 20 parts by weight of crosslinked heavy-weight fine particles having an average particle diameter of 0.01 to 10 μm, if necessary, and a coating film forming method.

20. An overcoating coating composition and a coating film forming method, wherein a substrate to be coated is an automobile body or an automobile part.

21. Crosslink density of the formed coating film is 4 ×
In ^{10 -3 mol / cc~10 × 10 -3} mol / cc, the dynamic Tg: top coat composition (Tg glass transition temperature) is 75 ° C. to 95 ° C. and film forming method.

[0114]

As described above, according to the top coating composition of the present invention, the total amount of lactone is 5 to 25% by weight based on the solid content of the component (A), the polyester resin, and the amount of lactone is different. Since it contains one type of lactone-modified hydroxyl group-containing polyester resin, the dynamic Tg of the main resin
And the crosslinking density of the coating film can be increased by the onium salt of the component (C) which is a curing catalyst. Therefore, the crosslink density can be increased without increasing the static Tg of the coating film, and the chipping resistance and abrasion resistance can be improved.

Further, according to the coating film forming method of the present invention, the above-mentioned top coating film having improved chipping resistance and abrasion resistance is applied onto (a) the under coating film and (b) electrodeposition coating. On the membrane,
(C) on the intermediate coating film formed on the electrodeposition coating film, (d) on the chipping primer coating film formed on the electrodeposition coating film,
(E) On the chipping primer coating, the intermediate coating, which are sequentially formed on the electrodeposition coating, (f) On the intermediate coating, the tipping primer coating, which are sequentially formed on the electrodeposition coating, (g) It can be formed on a coated substrate.

Therefore, when a coating film is formed on the body or parts of an automobile using the top coating composition of the present invention, a top coating film excellent in chipping resistance and abrasion resistance can be formed.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a state of forming a coating film by a coating film forming method of the present invention.

FIG. 2 Crosslink density and dynamic T of the top coating composition of the present invention
It is a figure explaining the relationship with g.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C09D 175/06 PHW

Claims (2)

[Claims] 1. (A) At least two lactone-modified hydroxyl group-containing polyester resins having a total amount of lactone per solid content of polyester resin of 5 to 25% by weight and different lactone amounts, (B) a cross-linking agent, and (C). and acyclic or cyclic sulfonium cation acyclic or cyclic ammonium cation or said benzyl group is bonded to a sulfur atom which benzyl group is bonded to the nitrogen atom of formula (I) shown below of 1, AsF ₆ ^- , SbF _{6
^{-, BF 4 -, PF 6}} -, ClO 4 -, FeCl 4 -,
An onium salt of CF ₃ SO ₃ ⁻ , an aromatic or aliphatic sulfonate ion or an aromatic or aliphatic carboxylate ion, and A top coating composition comprising: 2. (A) At least two lactone-modified hydroxyl group-containing polyester resins having a total lactone amount of 5 to 25% by weight per solid content of the polyester resin and different lactone amounts, (B) a crosslinking agent, and (C) and acyclic or cyclic sulfonium cation acyclic or cyclic ammonium cation or said benzyl group is bonded to a sulfur atom which benzyl group is bonded to the nitrogen atom of formula (I) shown below of 2, AsF ₆ ^- , SbF _{6
^{-, BF 4 -, PF 6}} -, ClO 4 -, FeCl 4 -,
CF ₃ SO ₃ ^-, an aromatic or aliphatic sulfonic acid ion or an aromatic or aliphatic carboxylic acid ion, an onium salt, ## STR2 ## A method for forming a coating film, which comprises coating the top coating composition containing the above on at least one coating film or a substrate to be coated according to the following (a) to (g). (A) Undercoat coating film, (b) Electrodeposition coating film, (c) Intermediate coating film formed on the electrodeposition coating film, (d) Chipping primer coating film formed on the electrodeposition coating film, (e) ) A chipping primer coating film, an intermediate coating film, which are sequentially formed on the electrodeposition coating film, (f) an intermediate coating film, a chipping primer coating film, which are sequentially formed on the electrodeposition coating film, (g) a substrate to be coated.