JPH08109234A - Low-solvent type resin composition, coating composition using the same and method of applying the composition - Google Patents

Abstract

PURPOSE: To provide a low-solvent type coating compsn. which can form a coating, excellent particularly in film properties such as weather, scratch, chip ping, and gasoline resistances, on coating objects such as automobiles. CONSTITUTION: A vinyl-polymerized oligomer contg. an acetoacetoxy group as an indispensable functional group in an amt. of 0.5 to 4.0mol/kg-resin, having a total functional group content of 2.5 to 4.0mol/kg-resin, a number average mol.wt. of 600 to 1500, and wt. average mol.wt. of 600 to 3000, and a wt. average mol.wt. to number average mol.wt. ratio of 1.0 to 2.0, an isocyanate prepolymer or a resin, and optionally a catalyst are incorporated as coating forming components. The coating has an org. solvent content of 0 to 40%.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a low solvent type resin composition,
A clear coating, an intermediate coating, a solid color and a base coat coating for an object to be coated such as an automobile containing the low solvent type resin composition, particularly a low solvent type coating composition suitable for a clear coating for automobiles, and a low solvent type thereof. The present invention relates to a method for coating a coating composition.

[0002]

2. Description of the Related Art In recent years, in paints using an organic solvent, strict restrictions are imposed on the release of the organic solvent in order to prevent the environment from being polluted by vaporization of the organic solvent constituting the paint. It is in. For this reason, high solids coating compositions that greatly reduce the amount of organic solvent or do not substantially use organic solvents have been widely studied. For the purpose of reducing the amount of organic solvent, water-based paints that do not use or practically do not use organic solvents, and powder paints have been widely studied, but water-based paints have poor water resistance and the amount of organic solvent is still low. About 20% is required. Further, in the powder coating, since it is necessary to use a resin having an extremely high glass transition temperature, the coating film tends to become brittle,
It has been a problem that weather resistance, scratch resistance, and gasoline resistance required for clear paints cannot be satisfied. Therefore, there has been a strong demand for a coating material which is capable of greatly reducing the limit of the amount of organic solvent which can be coated and which is excellent in coating film characteristics such as weather resistance, scratch resistance and gasoline resistance.

[0003]

SUMMARY OF THE INVENTION Therefore, according to the present invention, it is possible to significantly reduce the limit of the amount of organic solvent which can be coated, and yet to obtain excellent coating properties such as weather resistance, abrasion resistance and gasoline resistance. It is an object of the present invention to provide a novel low solvent type resin composition having the above, a low solvent type coating composition containing such a low solvent type resin composition, and a coating method thereof.

[0004]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has used a specific functional group called an acetoacetyl group, and has a vinyl polymerized oligomer having this functional group. By setting the number average molecular weight, the weight average molecular weight / number average molecular weight and the weight average molecular weight to a specific range and using an isocyanate prepolymer or a melamine resin as a curing agent, it was found that the above object can be achieved, and the present invention is achieved. It has arrived. The acetoacetyl group as a functional group of the vinyl polymerized oligomer used in the present invention exists as a keto-enol tautomer, and therefore has a property as a hydroxyl group as well as a property as a ketone group. Conventionally, a system in which a hydroxyl group and an isocyanate prepolymer or a melamine resin are used in combination is known, but the acetoacetyl group is significantly different from the hydroxyl group in that it does not have active hydrogen. The combination of isocyanate prepolymers or melamine resins, on the other hand, was unpredictable to those skilled in the art. Moreover, by adopting such a combination, it is possible to obtain an excellent effect that the viscosity can be significantly reduced in the system of the hydroxyl group and the isocyanate prepolymer or the melamine resin. The present invention has been made based on such novel findings.

That is, the present invention is as follows: 0.5 to 4 with an acetoacetyl group as an essential functional group.
It contains 0 mol / kg resin, the total amount of functional groups is 2.5 to 4.0 mol / kg resin, and the number average molecular weight is 600 to 150.
0, the weight average molecular weight is 600 to 3000,
A vinyl polymerized oligomer having a weight average molecular weight / number average molecular weight of 1.0 to 2.0, and a curing agent selected from an isocyanate prepolymer and a melamine resin, and having an organic solvent amount of 0 to 40%. 1. A low-solvent type resin composition characterized by being 1. 0.5 to 4 with an acetoacetyl group as an essential functional group.
It contains 0 mol / kg resin, the total amount of functional groups is 2.5 to 4.0 mol / kg resin, and the number average molecular weight is 600 to 150.
0, the weight average molecular weight is 600 to 3000,
A vinyl polymerized oligomer having a weight average molecular weight / number average molecular weight of 1.0 to 2.0 and a curing agent composed of an isocyanate prepolymer, and an organic solvent amount of 0 to 40.
%, A low-solvent type coating composition, 0.5 to 4 with an acetoacetyl group as an essential functional group.
It contains 0 mol / kg resin, the total amount of functional groups is 2.5 to 4.0 mol / kg resin, and the number average molecular weight is 600 to 150.
0, the weight average molecular weight is 600 to 3000,
Catalyze the reaction between a vinyl polymerized oligomer having a weight average molecular weight / number average molecular weight of 1.0 to 2.0, a curing agent selected from an isocyanate prepolymer and a melamine resin, the acetoacetyl group and the curing agent. 3. A low-solvent type coating composition containing a curing catalyst and having an organic solvent amount of 0 to 40%. 4. A coating method, which comprises coating the surface of an article to be coated with the low-solvent type coating composition according to the above 2 or 3 and then thermosetting to form a coating film on the surface of the article to be coated. A method for coating the surface of an article to be coated with the low solvent type coating composition according to 2 or 3 above, wherein the surface of the article to be coated is rotatably supported about a substantially horizontal axis. On the surface extending in the direction, paint is applied to a film thickness that causes sagging, and then the sagging of the paint applied to the surface of the object to be coated begins to rotate about the horizontal axis before the sagging occurs due to gravity. , And the speed at which the surface of the object to be coated transitions from a substantially vertical state to a substantially horizontal state before at least the rotation of the applied coating is caused by gravity and moreover than the speed at which the coating is sagged by the centrifugal force due to the rotation. 5. A method for coating a low-solvent type coating composition, characterized by rotating at a slow speed, and 6. The low solvent type coating composition according to the above 2 or 3 is 30 to
The present invention relates to a coating method, which comprises coating the surface of an object to be coated at 80 ° C.

The present invention will be described in detail below.
The acetoacetyl group contained in the vinyl polymer oligomer of the present invention is a functional group represented by the formula: CH ₃ —CO—CH ₂ CO—. The vinyl polymerized oligomer used in the present invention has a number average molecular weight (Mn) of 600 to 1500. Number average molecular weight is 6
When it is less than 00, the coating film forming ability is lowered, the strength of the obtained coating film is lowered, and the gasoline resistance and the scratch resistance are lowered. On the other hand, when the number average molecular weight is more than 1500, the viscosity of the paint becomes too high, and it is difficult to obtain a low solvent type paint. The preferred number average molecular weight is 7
00 to 1400, particularly preferably 700 to 1
It is 300. The weight average molecular weight / number average molecular weight (Mw / Mn) of the vinyl polymerized oligomer is 1.0 to 2.0. When the weight average molecular weight / number average molecular weight is more than 2.0, a relatively large amount of a vinyl polymerized oligomer having a too large molecular weight or a vinyl polymerized oligomer having a too small molecular weight is contained, and when the molecular weight is too large or small. The problem arises when it passes. The lower limit is theoretically 1.0, and the smaller the molecular weight of the vinyl polymerized oligomer, the easier it is to approach the theoretical value, and a coating composition having extremely uniform properties can be obtained. A preferable weight average molecular weight / number average molecular weight is 1.0 to 1.9, and particularly preferable is 1.0 to 1.8. The weight average molecular weight (Mw) of the vinyl polymerized oligomer used in the present invention is 600 to 3000 corresponding to the above number average molecular weight and weight average molecular weight / number average molecular weight. A preferred weight average molecular weight is 700 to 2800, and a particularly preferred value is 70.
It is 0-2600. The glass transition temperature of the vinyl polymerized oligomer used in the present invention is preferably -35.
C. to 40.degree. C., particularly preferably -10 to 30.degree. Four
If the glass transition temperature is higher than 0 ° C., the viscosity of the coating material becomes too high, which is not preferable. On the other hand, when the glass transition temperature is lower than -35 ° C, the coating film becomes too soft,
It is also not preferable because the gasoline resistance is deteriorated.

The vinyl polymerized oligomer used in the present invention may have a hydroxyl group or a blocked hydroxyl group together with the acetoacetyl group. Further, a vinyl polymerized oligomer containing an acetoacetyl group and a vinyl polymerized oligomer containing a hydroxyl group or a blocked hydroxyl group may be used in combination. The blocked hydroxyl group can be used without particular limitation as long as it is a hydroxyl group blocked by a blocking group that liberates the hydroxyl group by heat and / or moisture. Such a blocked hydroxyl group is represented by the following formula (1): --O--Z (1). Here, Z is a blocking group derived from the blocking agent bonded to the oxygen atom of the hydroxyl group. As Z, a block group represented by the following formula can be exemplified as a preferable one. [1] Silyl Block Group As the silyl block group, a silyl block group represented by the following formula (2) can be exemplified.

[0008]

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R ^{1 to} R ³ in the above formula (2) are each independently an alkyl group or an aryl group. Examples of the alkyl group include linear or branched alkyl groups having 1 to 10 carbon atoms, such as methyl group, ethyl group, propyl group, butyl group, s-butyl group, t-butyl group, pentyl group. And lower alkyl groups having 1 to 8 carbon atoms such as hexyl group are particularly preferable. The aryl group includes a phenyl group which may have a substituent, a naphthyl group, an indenyl group and the like, and a phenyl group is particularly preferable. Examples of the silyl block group represented by the formula (2) include a trimethylsilyl group,
Diethylmethylsilyl group, ethyldimethylsilyl group, butyldimethylsilyl group, butylmethylethylsilyl group,
Examples thereof include a phenyldimethylsilyl group, a phenyldiethylsilyl group, a diphenylmethylsilyl group and a diphenylethylsilyl group. In particular, the smaller the molecular weight of R ^{1 to} R ^3, the smaller the volatile components and the smaller the amount of the organic solvent, which is preferable. As a blocking agent for forming such a silyl block group, halogenated silane can be preferably used. Examples of the hagen atom contained in the halogenated silane include chlorine atom and bromine atom. Specific examples of the blocking agent include trimethylsilyl chloride, diethylmethylsilyl chloride, ethyldimethylsilyl chloride, butyldimethylsilyl bromide, butylmethylethylsilyl bromide, and the like. [2] Vinyl ether block group As the vinyl ether block group, a vinyl ether block group represented by the following formula (3) is exemplified.

[0010]

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R ¹ , R ² and R ³ in the above formula (3) are each independently a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms. R ⁴ is a hydrocarbon group having 1 to 18 carbon atoms. Y is an oxygen atom or a sulfur atom. Also, R ³ and R ⁴
And may combine with each other to form a heterocycle having Y as a heteroatom. As the hydrocarbon group in the above formula,
Examples thereof include an alkyl group, a cycloalkyl group and an aryl group. As the alkyl group, for example, methyl group, ethyl group, propyl group, butyl group, s-butyl group, t-butyl group,
A lower alkyl group having 1 to 8 carbon atoms such as a pentyl group and a hexyl group is particularly preferable. Examples of the cycloalkyl group include a cyclopentyl group and a cyclohexyl group. The aryl group may have a substituent,
Includes phenyl group, naphthyl group, anthracene group, etc.,
Particularly, a phenyl group is preferable. Such a vinyl ether blocking group can be formed by reacting an aliphatic vinyl ether or thioether or a cyclic vinyl ether or thioether with a hydroxyl group of a carboxyl group. Examples of the aliphatic vinyl ether include methyl vinyl ether, ethyl vinyl ether, isopropyl vinyl ether, n-propyl vinyl ether, isobutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether and the like, or a vinyl thioether corresponding thereto. Examples of the cyclic vinyl ether include 2,3-dihydrofuran,
3,4-dihydrofuran, 2,3-dihydro-2H-pyran, 3,4-dihydro-2H-pyran, 3,4-dihydro-2-methoxy-2H-pyran, 3,4-dihydro-4,4 -Dimethyl-2H-pyran-2-one, 3,4
-Dihydro-2-ethoxy-2H-pyran, 3,4-dihydro-2H-pyran-2-carboxylic acid sodium and the like can be mentioned.

Vinyl polymerized oligomer 1 used in the present invention
The amount of acetoacetyl group contained in the molecule is 0.5 to
4.0 mol / kg resin, preferably 1.0 to 3.5 mol / kg
kg resin. If the amount is less than 0.5 mol / kg resin, the crosslinking becomes insufficient and the scratch resistance and the gasoline resistance deteriorate. On the other hand, when the amount is more than 4.0 mol / kg resin, the crosslink density becomes too high and the coating film becomes brittle. The amount of optionally used hydroxyl groups or blocked hydroxyl groups is generally from 0 to
It is 4.0 mol / kg resin, preferably 0 to 3.0 mol / kg resin. If it is more than 4.0 mol / kg resin, the viscosity becomes too high, which is not preferable. The ratio of acetoacetyl groups and hydroxyl groups or blocked hydroxyl groups used (as mol / kg resin) is generally 0.3 or more: 1 and preferably 1 or more: 1. The amount of acetoacetyl groups
When it is less than 0.3: 1, the viscosity becomes high, which is not preferable. The number of all functional groups in one molecule of the vinyl polymerized oligomer used in the present invention is 2.5 to 4.0 mol / kg resin, preferably 3.0 to 4.0 mol / kg resin. If the total number of functional groups is less than 2.5 mol / kg resin, vinyl polymerized oligomers having no functional groups will be produced.
Crosslinking becomes insufficient, which is not preferable. On the other hand, when the number of all functional groups is more than 4.0 mol / kg resin, the viscosity becomes too high and the crosslink density becomes too high.
The coating becomes brittle and the coating performance is significantly reduced. When selecting the total number of functional groups, it is particularly necessary to consider the relationship with the molecular weight of the oligomer. That is, when the molecular weight of the vinyl-polymerized oligomer is small, unless the total number of functional groups is increased, a vinyl-polymerized oligomer having no functional groups in one molecule is produced, and thus the coating film performance cannot be sufficiently exhibited. Also, when the molecular weight of the vinyl polymerized oligomer is large, the viscosity itself becomes large, which is not preferable. In any case, the appropriate combination of molecular weight and total functional group can be readily determined empirically by a person skilled in the art within the scope of the invention.

The vinyl polymerized oligomer used in the present invention is prepared by polymerizing a monomer having an acetoacetyl group as an essential functional group and a polymerizable unsaturated bond alone, or by using such a monomer as an optional functional group. It can be obtained by copolymerizing with a monomer having a hydroxyl group or a blocked hydroxyl group as described above, or another copolymerizable monomer.
For example, when a vinyl polymerized oligomer is synthesized from an acrylic acid or methacrylic acid monomer having such a functional group, a (meth) acrylic oligomer is obtained. The method of polymerizing these monomers can be carried out by a known conventional means. For example, the polymerization can be performed by anionic polymerization, ionic polymerization such as cationic polymerization, or radical polymerization. In the present invention, radical polymerization is preferred from the viewpoint of ease of polymerization. However, in the present invention, since it is necessary to produce a low-molecular weight vinyl-polymerized oligomer, during the polymerization, a mercaptoethanol such as mercaptoethanol, thioglycerol, lauryl mercaptan or the like, so that the vinyl-polymerized oligomer can be produced at a low molecular weight, or Method using chain transfer agent, 60
It is desirable to employ a method of reacting at ˜180 ° C., a method of reacting at a low monomer concentration, or the like. When polymerizing a hydroxyl group-containing monomer blocked with a vinyl ether group, it is preferable to carry out the polymerization at 60 to 100 ° C. When the polymerization is carried out at a temperature higher than 100 ° C,
Blocking groups are easily dissociated. The molecular structure of the vinyl polymerized oligomer is not particularly limited, and various structures such as linear, comb-shaped, block-shaped, star-shaped, star-burst-shaped can be used. Radical polymerization
It is desirable to do it in solution. As a solvent used for such radical solution polymerization, a solvent conventionally used for polymerization of a vinyl polymerizable monomer such as an acrylic monomer can be used without limitation. Examples of such a solvent include toluene, xylene, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, Solvesso (manufactured by Exxon) and the like. As the radical reaction initiator used in radical solution polymerization, a reaction initiator conventionally used in radical polymerization can be used without limitation. Examples of such a reaction initiator include peroxides such as benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, t-butyl peroxy-2-ethylhexanol, azobis valeronitrile, and azobis. Isobutyronitrile,
Azo compounds such as azobis (2-methylpropionitrile) can be mentioned.

As the monomer having an acetoacetyl group, a monomer having an acetoacetyl group and a radical polymerizable unsaturated bond group is preferably used. Examples of such a monomer include the following formulas (4-1) to (4-
The monomer shown in 4) can be preferably mentioned.

[0015]

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In the above formula, R ¹ and R ³ are a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, R ² is an alkylene group,
Is a cycloalkylene group or an arylene group, and Y is -C
OO-, a single bond or -O-, and Z is an acetoacetyl group. Here, as the alkyl group having 1 to 6 carbon atoms, for example, a linear or branched alkyl group is included, and examples thereof include a methyl group, an ethyl group, a propyl group, and an n-butyl group s-
Butyl group, t-butyl group, n-pentyl group, s-pentyl group,
Hexyl group, n-heptyl group, s-heptyl group, octyl group, nonyl group, decyl group, undecyl group and the like can be mentioned. Preferred alkyl groups include a methyl group and an ethyl group. The alkylene group includes a linear or branched alkylene group having 1 to 18 carbon atoms, and examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, an isobutylene group, and a hexamethylene group having 1 to 6 carbon atoms.
And lower alkylene groups of Examples of the cycloalkylene group include cycloalkylene groups having 5 to 18 carbon atoms, and preferably cyclopentylene groups and cycloalkylene groups having 5 to 8 carbon atoms such as cyclohexylene groups. Examples of the arylene group include an ortho-, meta- or para-phenylene group, a naphthalene group, a fluorene group, an indole group, an anthracene group, a furan group and a thiophene group. Specific examples of the monomer represented by the above formula (4-1) include acetoacetoxyethyl (meth) acrylate, acetoacetoxypropyl (meth) acrylate, acetoacetoxyethyl crotonate, and acetoacetoxypropyl crotonate. To be Specific examples of the monomer represented by the above formula (4-2) include allyl acetoacetate and the like. Specific examples of the monomer represented by the above formula (4-3) include N- (2-acetoacetoxyethyl) (meth) acrylamide. Furthermore, examples of specific monomers represented by the above formula (4-4) include vinyl acetoacetate. The acetoacetyl group-containing monomer has the formula (4-1) above.
In, a (meth) acrylic monomer in which R ³ is a hydrogen atom and Y is —COO— is preferable. Specific preferred monomers include, for example, 2-acetoacetoxyethyl (meth) acrylate, 3-acetoacetoxypropyl (meth) acrylate, and 4-acetoacetoxybutyl (meth) acrylate. The synthesis of these acetoacetyl group-containing monomers is a technique known to those skilled in the art. For example, it can be synthesized by acetoacetylating a hydroxyl group-containing α, β-ethylenically unsaturated monomer with acetoacetic acid ester or diketene.

As the monomer used for imparting the hydroxyl group introduced into the optionally used vinyl polymerized oligomer of the present invention, a monomer in which Z is a hydrogen atom in the above formula (4-1) is preferably used. can do. Specific preferred hydroxyl group-containing monomers include hydroxyl group-containing (meth) acrylic monomers, such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and the like. Examples thereof include lactone-modified products. Preferable examples of the monomer having a blocked hydroxyl group include monomers obtained by blocking the hydroxyl group of the above-mentioned hydroxyl group-containing monomer. Further, a compound having an epoxy group is reacted with a monomer having a carboxyl group such as (meth) acrylic acid, or a compound having a carboxyl group is reacted with a monomer having an epoxy group such as glycidyl (meth) acrylate. You may get it.

Examples of the blocked hydroxyl group-containing monomer having a silyl block group include trimethylsiloxyethyl (meth) acrylate, trimethylsiloxypropyl (meth) acrylate, trimethylsiloxybutyl (meth) acrylate, triethylsiloxyethyl (meth) acrylate, Examples thereof include tributylsiloxypropyl (meth) acrylate and triphenylsiloxyethyl (meth) acrylate. Examples of the monomer having a silyl block group further include N-methylolated (meth) acrylamide, β-hydroxyethyl (meth) acrylate obtained by addition reaction of ε-caprolactone, and (meth) polyoxyalkylene glycol. A silyl-blocked acrylate can be used. Examples of the monomer having a hydroxyl group blocked with an aliphatic vinyl ether include 1-methylethoxyethyl (meth) acrylate, 1-ethylethoxy (meth) acrylate, 1-butylethoxy (meth) acrylate and 1- (2-ethylhexyl) ethoxyethyl. Mention may be made of 1-alkyl-alkoxy-alkyl (meth) acrylates such as (meth) acrylate, 1-isobutylethoxyethyl (meth) acrylate, 1-cyclohexylethoxyethyl (meth) acrylate. Furthermore, N-methylolated (meth) acrylamide and β-hydroxyethyl (meth) acrylate have ε-
It is possible to use those obtained by addition reaction with caprolactone or those obtained by blocking (meth) acrylate of polyoxyalkylene glycol with aliphatic vinyl ether. As the monomer having a hydroxyl group blocked with a cyclic vinyl ether, a monomer represented by the following formula (5) can be exemplified.

[0019]

[Chemical 4]

In the above formula, Z is a tetrahydrofuran group,
Examples thereof include a tetrahydropyran group and a group represented by the following formula (6).

[0021]

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When the vinyl polymerized oligomer used in the present invention is produced, other polymerizable monomers such as α, β-ethylenically unsaturated monomers may be used in combination, if necessary. As such α, β-ethylenically unsaturated monomer, for example, the following monomers can be used.

(1) Acrylic acid or methacrylic acid ester: For example, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate,
Lauryl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate,
C1 to C18 alkyl group esters of acrylic acid or methacrylic acid such as octyl methacrylate and lauryl methacrylate; methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, ethoxybutyl acrylate. , C2 to C18 alkoxyalkyl esters of acrylic acid or methacrylic acid esters such as ethoxybutyl methacrylate; C2 to C8 alkenyl esters of acrylic acid or methacrylic acid such as allyl acrylate and allyl methacrylate; allyl Oxyethyl acrylate,
An alkenyloxyalkyl ester having 3 to 18 carbon atoms of acrylic acid or methacrylic acid such as allyloxyethyl methacrylate.

(2) Vinyl compounds: For example, vinyl acetate, hexafluoropropylene, tetrafluoropropylene, styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene. (3) Polyolefin compound: For example, butadiene,
Isoprene, chloroprene. (4) Allyl ethers: hydroxyethyl allyl ether and the like. (5) Others: For example, methacrylamide, acrylamide, diacrylamide, dimethacrylamide, acrylonitrile, methacrylonitrile, methyl isopropenyl ketoin, vinyl acetate, vinyl propionate, vinyl pivalate, acrylic acid, methacrylic acid, N, N. -Phosphoric acid group-containing (meth) acrylates such as dialkylaminoalkyl (meth) acrylate and phosphonooxyethyl (meth) acrylate; perfluorovinyl ethers such as trifluoromethyl vinyl ether; vinyl ethers such as hydroxyethyl vinyl ether and hydroxybutyl vinyl ether.

The curing agents used in the present invention are isocyanate prepolymers and melamine resins. The acetoacetyl group exists as a keto-enol tautomer and has a property as a hydroxyl group. Isocyanate prepolymer and melamine resin utilize the property of the acetoacetyl group as a hydroxyl group to react with an acetoacetyl group,
It is a curing agent that crosslinks and cures the resin. As the isocyanate prepolymer, a polymer of polyisocyanate,
An addition reaction product of polyisocyanate and water or a polyhydric alcohol is mentioned. Here, as the polyisocyanate, a polyisocyanate having a plurality of isocyanate groups is used. The number of isocyanate groups is generally 2-6.
The number is preferably 2 to 4. Diisocyanate is particularly preferably used as the polyisocyanate. Examples of such diisocyanates include xylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,10-decamethylene diisocyanate, 1,1
Examples thereof include 8-octadecamethylene diisocyanate, lysine diisocyanate, lysine triisocyanate and the like. As these diisocyanates, lysine diisocyanate, lysine triisocyanate and hexamethylene diisocyanate are preferable.

Examples of the polyisocyanate polymer include polyisocyanate compounds in which a plurality of polyisocyanates are bonded to form a ring. Preferred examples of such a cyclic polyisocyanate include isocyanurates having an isocyanuric ring. Polyisocyanate reacts with water or a polyhydric alcohol to give an addition reactant having a plurality of isocyanate groups. The burette body is formed from the reaction of polyisocyanate and water. Examples of the polyhydric alcohol used here include dihydric or trihydric, and further tetrahydric or higher alcohols, such as ethylene glycol, propylene glycol, 1,3-butylene glycol, and 2
-Methyl propane diol, 1,4-butyryl glycol, neopentyl glycol, 1,6-hexane glycol, 1,2-dodecane diol, glycerin, trimethylol propane, trimethylol ethane, pentaerythritol, dipentaerythritol, hydroxypivalin Examples thereof include acid neopentyl glycol ester, 1,4-cyclohexanedimethanol, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, and 1,4-hydroxyhydroquinone. Preferred specific isocyanate prepolymers include hexamethylene diisocyanate prepolymer which is a cyclic polymer (for example, Pernock 901S (manufactured by Dainippon Ink and Chemicals)) and Duranate TPA-100 (manufactured by Asahi Kasei). Melamine resins are produced by the polymerization of melamine and formaldehyde, the production methods of which are well known to those skilled in the art. As such a melamine resin, a melamine resin containing 40 to 100% of a mononuclear melamine represented by the following formula (7) is particularly preferable.

[0027]

[Chemical 6]

(In the formula, R ^{1 to} R ⁶ are independently a hydrogen atom,
It is a methylol group or an alkyl group having 1 to 5 carbon atoms. ) Here, when the mononuclear melamine is blended in the melamine resin in an amount less than 40%, the coating viscosity becomes too large, which is not preferable. Formula (7)
When the number of carbon atoms of the alkoxy group in is more than 5,
The viscosity becomes too high, which is not preferable. The preferred carbon number is 1 to 4. Specific examples of such an alkoxy group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group and an isobutoxy group. As an embodiment of the mononuclear melamine, R ^{1 to} R ^{6 in} the above formula (7) are all alkoxy type melamine resins in which all are alkoxy groups (for example, Cymel 303 and 113 manufactured by Mitsui Cyanamid).
0) and R ^{1 to} R ⁶ in the above formula (7) are all hydrogen atoms (for example, Cymel 325 and 327 manufactured by Mitsui Cyanamid), and further in the above formula (7).
A methylol-type melamine resin in which R ^{1 to} R ⁶ are all methylol groups (for example, Cymel 37 manufactured by Mitsui Cyanamid).
0) and the like. The mononuclear melamine represented by the formula (7) is different from the binuclear or more melamine of the form in which two or more melamines are mutually bound by formaldehyde, but the mononuclear melamine represented by the formula (7) is As long as the content of nucleolar melamine is 40% or more, a melamine resin containing such binuclear or more melamine (polynuclear melamine resin)
You may use together.

The melamine resin containing 40 to 100% of the mononuclear melamine can be easily prepared by those skilled in the art. Generally, the amount of polynuclear melamine resin is adjusted to less than 40% or completely by reacting melamine represented by formula (7) with formaldehyde and then fractionating by gel permeation chromatography. Can be removed. When an isocyanate prepolymer is used as a curing agent, the isocyanate prepolymer generally has a content of 0.6 mol based on 1 mol of the acetoacetyl group of the vinyl polymerized oligomer used in the present invention.
~ 1.4 mol, preferably 0.8-1.2 mol, particularly preferably 0.9-1.1 mol. 0.
If the amount is less than 6 mol, the crosslinking density will be low,
It is not preferable because the gasoline resistance is deteriorated. On the other hand, 1.4
When it is used in an amount larger than the molar amount, the cross-linking density is reduced and the gasoline resistance is lowered. When using a melamine resin as a curing agent, the melamine resin, relative to the weight of the vinyl polymerized oligomer,
It is used in an amount of 20 to 140% by weight, preferably 40 to 100% by weight. When the amount of the melamine resin is less than 20% by weight, the crosslink density becomes low and the gasoline resistance is lowered, which is not preferable. On the other hand, when it is used in an amount of more than 140% by weight, the self-condensation reaction of melamine increases, the coating film becomes brittle, and the weather resistance decreases, which is also not preferable. As a curing agent, mononuclear melamine is 40 to 10
A 0% melamine resin is particularly preferred for the purpose of lowering the viscosity. In the low solvent resin composition of the present invention, the above isocyanate prepolymer and melamine resin may be mixed and used. As a blending ratio in that case, the amount of the melamine resin is generally 0.1 to 99.9% by weight, preferably 0.1 to 80% by weight.

In the low solvent type coating composition of the present invention,
The reaction between the acetoacetyl group-containing vinyl polymerized oligomer and the curing agent does not particularly require a curing catalyst when an isocyanate prepolymer is used as the curing agent.
However, it is preferable to add such a curing catalyst from the viewpoint of improving the efficiency of the painting work. On the other hand, it is appropriate to use a curing catalyst in the reaction between the vinyl polymerized oligomer containing an acetoacetyl group and the melamine resin. An acid catalyst is used as the curing catalyst. As an acid catalyst,
For example, a strongly acidic catalyst or a weakly acidic catalyst is used. Examples of the strongly acidic catalyst include inorganic acids such as hydrochloric acid, nitric acid and sulfuric acid, organic acids such as sulfonic acid, and salts thereof such as esters, ammonium salts and onium salts thereof. Particularly, as the strongly acidic catalyst, sulfonic acid, its ester or amine salt, benzoic acid, trichloroacetic acid and the like are preferable. Specifically, examples of the sulfonic acid include aliphatic sulfonic acids such as methanesulfonic acid and ethanesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, naphthalenedisulfonic acid, dinonylnaphthalenesulfonic acid, and dinonyl. Examples thereof include aromatic sulfonic acids such as naphthalene disulfonic acid. As the strongly acidic catalyst, aromatic sulfonic acid or its ester is preferable, and specifically, p-toluenesulfonic acid and dinonylnaphthalene disulfonic acid are particularly preferable because they improve the water resistance of the coating film. On the other hand, examples of the weakly acidic catalyst include phosphoric acids, phosphoric acid monoesters, phosphorous acid esters, unsaturated group-containing phosphoric acid esters, and the like. As the weakly acidic catalyst, phosphoric acid or its ester is particularly preferable. Examples of such phosphoric acids or esters thereof include phosphoric acid, pyrophosphoric acid, and phosphoric acid mono- or diesters. Examples of the phosphoric acid monoester include monooctyl phosphate, monopropyl phosphate, monolauryl phosphate and the like. Examples of the phosphoric acid diester include dioctyl phosphate, dipropyl phosphate, dilauryl phosphate and the like. Furthermore, mono (2- (meta))
Acryloyloxyethyl) acid phosphate. The curing catalyst is 0.001 to 10%, preferably 0.001 to 5%, based on the weight of the vinyl polymerized oligomer and the curing agent. When a vinyl-polymerized oligomer containing a blocked hydroxyl group is used in combination, in order to generate a free hydroxyl group from this blocked hydroxyl group,
An acidic dissociation catalyst can be used if necessary. The range of this acidic dissociation catalyst is the same as the range of the above curing catalyst, and therefore, the curing catalyst can act simultaneously as a dissociation catalyst.

In order to enhance the properties of the low-solvent type coating composition of the present invention, a compound having a functional group such as a hydroxyl group or a blocked hydroxyl group, a hydrolyzable silyl group or an epoxy group is added as a reactive diluent, if necessary. Can be used as
Such compounds include compounds having an alicyclic epoxy group such as Celoxide 2021, Celoxide 2081, Celoxide 2083 (all manufactured by Daicel Chemical Industries, Ltd.),
Examples thereof include compounds having a hydrolyzable silyl group and an epoxy group such as TSL8350 and TSL8355 (above, manufactured by Toshiba Silicon), and compounds having a hydroxyl group such as octyl alcohol and 1,5-pentanediol. The viscosity of these compounds at 25 ° C. is 500 centipoise or less, preferably 300 centipoise or less. Above 500 centipoise, it has no effect as a diluent. The low-solvent coating composition of the present invention can be used as it is or, if necessary, various pigments conventionally used in the field of coatings (for example, color pigments and glitters), anti-sagging agents or anti-settling agents. It can be prepared by appropriately mixing an agent, a reverig agent, a dispersant, a defoaming agent, an ultraviolet absorber, a light stabilizer, an antistatic agent, a thinner and the like. Examples of the pigment or glittering agent include titanium oxide, carbon black, precipitated barium sulfate, calcium carbonate, talc, kaolin, silica, mica, aluminum, red iron oxide, lead chromate, lead molybdate, chromium oxide, cobalt aluminate, Azo pigments, phthalocyanine pigments, anthraquinone pigments and the like can be preferably used. As the anti-sagging agent or the anti-settling agent, for example, bentonite, castor oil wax, amide wax, microgel (for example, MG100S (manufactured by Dainippon Ink and Chemicals)) and the like can be preferably used. Examples of the leveling agent include silicon-based ones such as KF69, Kp321 and Kp301 (all manufactured by Shin-Etsu Chemical Co., Ltd.), Modaflow (manufactured by Mitsubishi Monsanto), BYK358, 301 (manufactured by Big Chemie Japan) and Dia-Aid AD9001 (Mitsubishi Rayon). Manufactured) and the like can be preferably used.

As the dispersant, for example, Anti-Terra U or Anti-Terra P and Disperbyk-101 (above, manufactured by Big Chemie Japan) can be preferably used.
As the defoaming agent, for example, BYK-O (manufactured by BYK Chemie Japan) or the like can be preferably used. Examples of the UV absorber include benzotriazole-based UV absorbers such as TINUVIN 900, TINUVIN 384, and TINUVIN P (all manufactured by Ciba Geigy), and anilide oxalate UV absorbers such as SANDVA-3206 (manufactured by Sand). It can be preferably used. Examples of the light stabilizer include sanol
Hindered amine light stabilizers such as LS292 (manufactured by Sankyo) and sand bar 3058 (manufactured by Sand) can be preferably used. Examples of the thinner include aromatic compounds such as toluene, xylene, and ethylbenzene, alcohols such as methanol, ethanol, propanol, butanol, and isobutanol, acetone, methyl isobutyl ketone, and the like.
Methyl amyl ketone, cyclohexanone, isophorone,
A ketone such as N-methylpyrrolidone, an ester compound such as ethyl acetate, butyl acetate, methyl cellosolve, or a mixture thereof can be used. As the antistatic agent, for example, Esocard C25 (manufactured by Lion Armor) or the like can be preferably used.

The low-solvent type coating composition of the present invention is particularly useful as a clear coating, an intermediate coating, a solid color coating and a base coating used for coating automobiles. In particular, the low solvent type coating composition of the present invention is particularly excellent as an intermediate coating composition. Further, the low solvent type coating composition of the present invention,
Each of them can be sequentially applied as an intermediate coating, a base coating and a clear coating, or a solid color coating and a clear coating. Furthermore, the low-solvent type coating composition of the present invention is used as an intermediate coating composition, and a base coat coating composition and a clear coating composition consisting of a conventionally known organic solvent-based coating composition or an aqueous coating composition are applied on the composition by wet-on-wet. be able to. Further, the low-solvent type coating composition of the present invention can be used as a base coat coating, and a conventionally known clear coating can be applied thereon. Further, a conventionally known base coat paint may be applied, and then a clear paint as the low solvent type paint composition of the present invention may be applied thereon by wet on wet.
In this case, as the base coat paint, for example, it is preferable to use a paint composition containing an oligomer having a hydroxyl group and a weight average molecular weight of 6000 or less, and a melamine resin. Such a base coat paint composition may be an organic solvent type paint or an aqueous paint. Further, the base coat coating composition preferably has a coating solid content of 35% by weight or more, particularly 40% by weight or more. The low-solvent type coating composition of the present invention can reduce the viscosity of the coating composition although the amount of the organic solvent is small. That is, even though the solvent amount of the paint can be greatly reduced as compared with the conventional one, it is possible to maintain the viscosity suitable for coating. For example, the amount of organic solvent can be 40% or less, preferably 35% or less, and particularly preferably 30% or less. The lower limit is 5%.

To apply the low solvent type coating composition of the present invention,
In order to prevent sagging even when applied thickly and to improve the surface smoothness, it is preferable to apply the object while rotating it around a horizontal axis. For example, JP-A-6
As disclosed in Japanese Laid-Open Patent Publication No. 3-178871, the object to be coated such as the body of an automobile is fixed from the vertical direction, and while rotating the body in the horizontal direction, the low solvent type coating composition of the present invention may be applied. , Or even when baked or dried,
It can be applied to a thickness equal to or more than the limit thickness (threshold film thickness) at which sagging when stationary occurs. The rotation is preferably continuous rotation and has a large sagging prevention effect. More specifically, it is a method for coating the surface of an article to be coated with the low-solvent type coating composition of the present invention, in which a normal upper and lower surface of the article to be coated rotatably supported about a substantially horizontal axis is provided. On the surface extending in the direction, paint is applied to a film thickness that causes sagging, and then the sagging of the paint applied to the surface of the object is started to rotate about the horizontal axis before the sagging occurs due to gravity. , And the speed at which the surface of the object to be coated transitions from a substantially vertical state to a substantially horizontal state before at least the rotation of the applied coating is caused by gravity, Rotate at a slow speed. The rotation speed is generally 0.2 to 120 rpm, preferably 5 to
It is 20 rpm. When the rotation speed is less than 0.2 rpm, the effect of preventing sagging is small, which is not preferable. on the other hand,
On the other hand, if it is higher than 120 rpm, the sagging is likely to occur due to centrifugal force, which is not preferable. Note that, for example,
It may be reversed in the order of 90 ° → 135 ° → 160 °. In this way, after coating while rotating the object to be coated around the horizontal axis, while maintaining its rotation, the paint is set vertically (usually without a heating device) or baked (with a heating device). Meanwhile, a coating film is formed by moving the object to be coated. The set (dry) is generally 5
It is carried out for 30 minutes, preferably for 5 to 15 minutes, at room temperature or ambient temperature. Baking is 60 to 200 ° C., preferably 8
It is preferable to carry out at 0 to 160 ° C. for 1 to 60 minutes, preferably 10 to 40 minutes. The low solvent type coating composition of the present invention,
By hot spraying, the paint can be applied while further reducing the amount of solvent. In such hot spraying, for example, the process from the tank storing the low solvent type coating composition to immediately before the spraying is kept at a predetermined temperature, generally 30 to 80 ° C, preferably 35 to 70 ° C. Can be done by In the low-solvent type coating composition of the present invention, the properties of the coating film to be formed, for example, various properties such as gasoline resistance, scratch resistance, weather resistance, and the appearance of the coating film have excellent quality. The amount of organic solvent can be reduced much more than ever. For example, the amount of organic solvent can be reduced to 40% or less, preferably 35% or less, and more preferably 30% or less. Therefore, the problem of environmental pollution due to the release of the organic solvent can be significantly reduced.

[0035]

EXAMPLES Next, the present invention will be described more concretely by reference examples, examples, application examples and comparative application examples. However, the scope of the present invention is not limited to only those examples. In the following, parts and% are based on weight unless otherwise specified.

Reference Examples 1-32: acetoacetyl group, hydroxy
Of an acrylic oligomer having a group or a blocked hydroxyl group
674 parts of xylene was charged into a four-necked flask equipped with a preparation stirrer, an inert gas inlet, a thermometer and a dropping funnel, and the temperature was raised to 140 ° C. with stirring. Then, a mixture of 160 parts of acetoacetoxyethyl methacrylate, 40 parts of styrene, 25 parts of n-butyl acrylate, 25 parts of 2-ethylhexyl methacrylate, and 26 parts of perbutyl-O (a peroxide made by NOF Corporation) and 24 parts of xylene. Was added dropwise over 4 hours, and the reaction was continued for another 2 hours. Then, 1 part of perbutyl-O and 1 part of xylene were dropped, and after reacting for 5 hours, the synthesis was completed. Xylene was distilled off under reduced pressure to obtain a solventless acrylic oligomer A-1. The following Table 1 shows the raw material composition and the properties of the resulting acrylic oligomer (A-1). Similarly, acrylic oligomers A-2 to 5, B-1 to 4,
C-1 to 4, D-1 to 4, E-1 to 4, F-1 to 4, G
-1 to 4 and H-1 to 3 were synthesized. However, in the synthesis of E-1 and G-2, the synthesis temperature was 80 ° C. The properties of these acrylic oligomers are also shown in Table 1.
It was shown to. In addition, H-1 is an example when the number average molecular weight is larger than 1500, and H-2 has a number average molecular weight larger than 1500, a weight average molecular weight larger than 3000, and a weight average molecular weight / number. Average molecular weight is 2.0
H-3 is an example where the number average molecular weight is less than 600. In Table 1, the following indications have the following meanings. AA group ………… acetoacetyl group OH group ………… hydroxyl group BOH group ………… blocked hydroxyl group AIBN ………… azoisobutyronitrile AIVN ………… azoisovaleronitrile P-O ………… t-butyl-per- 2-Ethylhexanoate Monomer A ... Blocked hydroxyl group-containing monomer represented by the following formula

[0037]

[Chemical 7]

Monomer B ... Blocked hydroxyl group-containing monomer 1 represented by the following formula

[0039]

Embedded image

Reference Example 33: Compound having vinyl ether group
In a synthetic flask containing 12 parts of trimethylolpropane, 3,
67 parts of 4-dihydro-2H-yl-methyl-3,4-dihydro-2H-pyran-2-carboxylate and acetic acid
34 parts of n-butyl was added and suspended. To this, 0.1 part of dodecylbenzenesulfonic acid was added, and the mixture was stirred at room temperature for 24 hours. After filtration, the solvent was evaporated under reduced pressure to give compound H
-4 was obtained.

[0041]

Table 1 Table 1 Reference Example 1 Reference Example 2 Reference Example 3 Reference Example 4 Nomenclature of Oligomer A-1 A-2 A-3 A-4 Characteristic of Oligomer Number average molecular weight (Mn) 720 1160 630 1463 Weight average molecular weight ( Mw) 1008 1740 1008 2780 Mw / Mn 1.4 1.5 1.6 1.9 Tg (° C) 13 37 13 13 13 Functional group amount (mol / kg resin) Total functional group amount 3.0 2.8 3. 0 3.0 AA group 3.0 2.8 3.0 3.0 Synthetic raw material xylene 674 674 674 674 acetoacetoxy 160 150 160 160 160 ethyl methacrylate styrene 40 40 40 40 40 n-butyl acrylate 25 30 25 25 2-ethylhexyl 25 30 25 25 methacrylate P-O 26 22 28 17 xylene 24 28 22 33 P-O 1 1 1 1 xylene 1 1 1 1

[0042]

[Table 2] Table 1 (continued) Reference Example 5 Reference Example 6 Reference Example 7 Reference Example 8 Name of Oligomer A-5 B-1 B-2 B-3 Characteristic of Oligomer Number average molecular weight (Mn) 740 700 1210 760 Weight Average molecular weight (Mw) 1184 1120 1815 1140 Mw / Mn 1.6 1.6 1.6 1.6 1.5 Tg (° C.) 9 18 22 18 Functional group amount (mol / kg resin) Total functional group amount 3.0 3. 0 3.0 3.0 AA group 3.0 2.0 1.0 2.0 OH group 1.0 2.0 1.0 Synthetic raw material xylene 674 674 674 674 acetoacetoxy 160 107 107 54 107 ethyl methacrylate hydroxyethyl meta 33 65 33 acrylate styrene 0 50 60 n-butyl acrylate 40 30 40 50 methyl methacrylate 50 60 2-ethylhexyl 30 31 Methacrylate P-O 22 26 22 26 Xylene 28 24 28 24 P-O 1 1 1 1 Xylene 1 1 1 1

[0043]

[Table 3] Table 1 (continued) Reference Example 9 Reference Example 10 Reference Example 11 Reference Example 12 Name of oligomer B-4 C-1 C-2 C-3 Characteristic number average molecular weight (Mn) 1180 730 1400 710 Weight of oligomer Average molecular weight (Mw) 1888 1095 2380 1065 Mw / Mn 1.6 1.5 1.7 1.5 Tg (° C) 158 -1-5 Functional group amount (mol / kg resin) Total functional group amount 3.0 3.0 3.0 3.0 AA group 1.0 2.0 1.0 2.0 OH group 2.0 BOH group 1.0 2.0 1.0 1.0 Synthetic raw material xylene 674 674 674 674 acetoacetoxy 54 107 54 107 Ethyl Methacrylate Hydroxyethyl Meth 65 Crylate Trimethylsiloxy 46 91 46 Ethyl Methacrylate Styrene 47 45 52 n-Butyl Acrylate 70 25 0 52 Methyl methacrylate 61 45 2-ethylhexyl 25 30 methacrylate P-O 22 26 19 26 Xylene 28 24 31 24 P-O 1 1 1 1 Xylene 1 1 1 1

[0044]

[Table 4] Table 1 (continued) Reference Example 13 Reference Example 14 Reference Example 15 Reference Example 16 Name of Oligomer C-4 D-1 D-2 D-3 Characteristic number average oligomer (Mn) 1420 720 1150 700 Weight Average molecular weight (Mw) 2414 1152 1725 980 Mw / Mn 1.7 1.6 1.5 1.5 1.4 Tg (° C) -5 4 10 5 Functional group amount (mol / kg resin) Total functional group amount 3.0 3 0.0 3.0 3.0 AA group 1.0 1.0 2.0 2.0 1.0 OH group 1.0 0.5 1.0 BOH group 2.0 1.0 0.5 0.5 1.0 Synthetic raw material xylene 674 674 674 674 acrylate 5 acetoacetoxy 54 54 107 54 methacrylate hydroxyethyl methacrylate 33 17 33 acrylate trimethylsiloxy 91 46 23 46 methacrylate styrene 7 43 n-Butyl acrylate 55 35 30 62 Methyl methacrylate 50 55 2-ethylhexyl 35 30 methacrylate P-O 19 26 22 26 Xylene 31 24 28 24 P-O 1 1 1 1 Xylene 1 1 1 1

[0045]

[Table 5] Table 1 (continued) Reference Example 17 Reference Example 18 Reference Example 19 Reference Example 20 Name of oligomer D-4 E-1 E-2 E-3 Characteristic number average molecular weight (Mn) 1140 730 1140 720 Weight of oligomer Average molecular weight (Mw) 1710 1241 1938 1152 Mw / Mn 1.4 1.7 1.7 1.6 Tg (° C.) 5 19 8 25 Functional group amount (mol / kg resin) Total functional group amount 3.0 3. 0 2.7 3.0 AA group 2.0 OH group 0.5 3.0 3.0 3.0 BOH group 0.5 Synthetic raw material xylene 674 674 674 674 acetoacetoxy 107 ethyl methacrylate hydroxyethyl meta 17 98 98 88 Crylate Trimethylsiloxy 23 Ethyl acrylate Styrene 52 62 n-Butyl acrylate 55 50 50 72 Methyl methacrylate 5 0 80 2-Ethylhexyl 50 50 Methacrylate P-O 22 26 22 22 26 Xylene 28 24 28 28 24 P-O 1 1 1 1 Xylene 1 1 1 1 1

[0046]

[Table 6] Table 1 (continued) Reference Example 21 Reference Example 22 Reference Example 23 Reference Example 24 Nomenclature of Oligomer E-4 F-1 F-2 F-3 Characteristic number of oligomer (Mn) 1180 750 1340 720 Weight Average molecular weight (Mw) 1770 1200 2144 1080 Mw / Mn 1.5 1.6 1.6 1.6 1.5 Tg (° C.) 20 2 5 0 Functional group amount (mol / kg resin) Total functional group amount 2.7 3. 0 3.0 3.0 OH group 2.7 BOH group 3.0 3.0 3.0 3.0 Raw material for synthesis Xylene 674 674 674 674 Hydroxyethylmetha 88 Crylate Trimethylsiloxy 137 137 Ethyl methacrylate Monomer A 143 Styrene 43 47 n-Butyl acrylate 81 30 30 53 methyl methacrylate 81 50 2-ethylhexyl 30 30 methacrylate P O 22 26 26 Xylene 28 24 21 24 ABNV 10 AIVN 10 P-O 1 1 1 1 Xylene 1 1 1 1

[0047]

[Table 7] Table 1 (continued) Reference Example 25 Reference Example 26 Reference Example 27 Reference Example 28 Name of Oligomer F-4 G-1 G-2 G-3 Characteristic Number of Oligomer Number Average Molecular Weight (Mn) 1210 770 1360 730 Weight Average molecular weight (Mw) 2057 1232 2040 1035 Mw / Mn 1.7 1.6 1.5 1.5 Tg (° C) 0 -1 22 -1 Functional group amount (mol / kg resin) Total functional group amount 3.0 3.0 3.0 3.0 OH group 1.0 2.0 1.0 1.0 BOH group 3.0 2.0 1.0 1.0 2.0 Synthetic raw material xylene 674 674 674 674 Hydroxyethylmetha 33 65 33 acrylate trimethylsiloxy 91 91 Ethyl methacrylate Monomer A 143 Monomer B 50 Styrene 46 55 n-Butyl acrylate 57 40 40 66 Methyl methacrylate 50 60 2-Ethylhexyl 40 40 Methacrylate P-O 26 26 Xylene 21 24 21 24 ABNV 10 AIVN 10 P-O 10 1 1 1 Xylene 10 1 1 1 1

[0048]

Table 1 (continued) Reference Example 29 Reference Example 30 Reference Example 31 Reference Example 32 Name of Oligomer G-4 H-1 H-2 H-3 Oligomer Characteristic Number Average Molecular Weight (Mn) 1280 1630 1760 500 Weight Average molecular weight (Mw) 2048 2830 4000 750 Mw / Mn 1.6 1.7 2.3 1.5 Tg (° C) 22 13 13 13 Functional group amount (mol / kg resin) Total functional group amount 3.0 3. 0 3.0 3.0 AA group 3.0 3.0 3.0 OH group 2.0 BOH group 1.0 Synthetic raw material Xylene 674 674 550 674 acetoacetoxyethyl 160 160 160 160 methacrylate hydroxyethylmetha 65 acrylate Monomer B 50 styrene 40 40 40 n-butyl acrylate 65 25 25 25 methyl methacrylate 70 2-ethylhexyl meth Relate 25 25 25 AIBN 10 P-O 18 16 28 AIVN 10 Xylene 21 32 24 22 P-O 1 1 1 Xylene 1 1 1

Preparation of paint 1. Preparation of clear paint According to the blending ratio shown in Table 2 below, clear paint C1
~ C16 was prepared.

[0050]

[Table 9] Table 2 Clear paint C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 A-1 100 50 50 A-2 100 60 B-1 100 B-2 100 C-1 100 C-2 100 D-1 100 D-2 100 E-1 50 E-2 40 F-1 50 Pernock 901S 54 50 54 54 30 49 54 Cymel 370 30 30 10 30 Cymel 303 30 Monophosphate phosphate 2 2 2 2 2 2 2 2 2 2 Cytyl paratoluene 2 Sulfone Acid Tinuvin 384 2 2 2 2 2 2 2 2 2 2 2 2 Sanol 1 1 1 1 1 1 1 1 1 1 1 LS292 Kp321 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05

[0051]

[Table 10] Table 2 (continued) C12 C13 C14 C15 C16 A-1 50 A-2 60 60 F-2 40 G-1 50 G-2 40 A-3 100 A-4 100 Pernock 901S 54 51 54 Cymel 370 30 30 Monooctyl phosphate 2 2 2 2 2 Tinuvin 384 2 2 2 2 2 Sanol LS292 1 1 1 1 1 Kp321 0.05 0.05 0.05 0.05 0.05

Preparation of Solid Color Paint 1. Preparation of pigment dispersion 50 parts of titanium oxide CR95 (manufactured by Ishihara Sangyo Co., Ltd.) was dispersed in 50 parts of the acrylic oligomers A to G to obtain pigment dispersions WA to WG. The blending was carried out for 1 hour using a motor mill (trade name of Eiger Co.) as a disperser. 2. Preparation of Solid Color Paints Using the obtained pigment dispersions WA to WG, solid paints S1 to S14 were prepared with the formulations shown in Table 3 below.

[0053]

[Table 11] Table 3 Solid color paint S1 S2 S3 S4 S5 S6 S7 S8 WA1 100 WA2 100 WB1 100 WB2 100 WC1 100 WC2 100 WD1 100 WD2 100 Pernock 901S 27 25 27 27 15 Cymel 370 15 15 5 Cymel 303 15 Phosphoric acid mono Octyl 2 2 2 2 2 2 Paratoluene 2 Sulfonate Tinuvin 384 2 2 2 2 2 2 2 2 Sanol LS292 1 1 1 1 1 1 1 1 Kp321 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05

[0054]

[Table 12] Table 3 (continued) S9 S10 S11 S12 S13 S14 WA1 50 50 50 WA2 60 60 60 WE1 50 WE2 40 WF1 50 WF2 40 WG1 50 WG2 40 Pernock 901S 25 27 27 26 Cymel 370 15 15 Monooctyl Phosphate 2 2 2 2 2 2 Tinuvin 384 2 2 2 2 2 2 Sanol LS292 1 1 1 1 1 1 Kp321 0.05 0.05 0.05 0.05 0.05 0.05

[0055] In accordance with the blending ratio described in Table 4 below Preparation of base coat paint was prepared a base coat paint B1～17.

[Table 13] Table 4 Base paint B1 B2 B3 B4 B5 B6 B7 B8 FR-606C 10 10 10 10 10 10 10 10 Toluene 10 10 10 10 10 10 10 10 A-5 50 B-3 50 B-4 50 C- 3 50 C-450 D-350 D-450 E-350 Cymel 370 14 14 14 14 14 14 14 14 MG100S 5 5 5 5 5 5 5 5 Monooctyl phosphate 2 2 2 2 2 2 2 2 Tinuvin 384 1 1 1 1 1 1 1 1 SANOL LS292 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Kp321 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 FR-606C is an aluminum paste manufactured by Asahi Kasei.

[0056]

[Table 14] Table 4 (continued) B9 B10 B11 B12 B13 FR-606C 10 10 10 10 10 Toluene 10 10 10 10 10 A-5 25 25 25 25 25 E-4 25 F-3 25 F-4 25 G- 3 25 G-425 Cymel 370 14 14 14 14 14 MG100S 5 5 5 5 5 Monooctyl phosphate 2 2 2 2 2 Tinuvin 384 1 1 1 1 1 Sanol LS292 0.5 0.5 0.5 0.5 0.5 Kp321 0.02 0.02 0.02 0.02 0.02

[0057]

[Comparative Example] Preparation of Comparative Clear Paint A comparative clear paint was prepared in the same manner as in the examples, based on the compounding ratios shown in Table 5 below.

[0058]

[Table 15] Table 5 CH1 CH2 CH3 CH4 H-1 100 H-2 100 H-3 100 H-4 80 A-1 100 Pernock 901S 54 54 54 Monooctyl phosphate 2 2 2 2 Tinuvin 384 2 2 2 2 10% Paratoluene 3 Sulfonate Sanol LS292 1 1 1 1 Kp321 0.05 0.05 0.05 0.05

Evaluation of paint performance 1. Preparation of Test Piece Using each of the above-mentioned paints, the minimum amount of solvent that gives a viscosity (100 centipoise) that can be applied at 25 ° C. and 60 ° C. was investigated, and the solvent content was calculated. The organic solvent used at this time was a mixed solution of xylene / cyclohexanone (weight ratio 50/50) for clear paints and solid color paints. For the base coat paint, toluene / methyl isobutyl ketone (weight ratio 50/50) was used. 2. Confirmation of paint performance (1) Clear paint Using Wider 77 as a paint gun, one of solvent-based base coat H500 (Nippon Paint Co., Ltd.) or water-based base coat H900 (Nippon Paint Co., Ltd.) is applied as an intermediate coating plate (OTO825). , Nippon Paint Co., Ltd.). After setting on the solvent type base coat for 10 minutes, on the water-based base coat, after drying at 100 ° C for 10 minutes, a clear paint is applied at 25 ° C and then at 150 ° C for 3 minutes.
It was baked in 0 minutes. (2) Solid color paint Using Wider 77 as a painting gun, the solid color paint is applied as an intermediate coating plate (OTO825, Nippon Paint Co., Ltd.).
Was applied at 25 ° C and baked at 150 ° C for 30 minutes. (3) Base coat paint Using a wiper 77 as a coating gun, a base coat paint was applied on an intermediate coated plate (OTO825, Nippon Paint Co., Ltd.) at 25 ° C, and OTO580 clear was applied 10 minutes after the base coat application. Baked at 30 ° C. for 30 minutes. The following various performance tests were performed on the coating film formed from each of the above paints, and the results are shown in Tables 6 to 8 below.

[0060]3. Performance evaluation method (1) Water resistance test Each coated plate was immersed in warm water at 60 ° C for 10 days and cross-cut.
A tape peeling test (adhesion test) was performed. Water resistance test
In ◎, if there is no peeling of paint, ◎, peeling is 5 in area
Those with less than 5% were evaluated as ◯, and those with 5% or more were evaluated as x. (2) Solvent content 25% and 60 ° C hot sprayable limit
The solvent content (%) in field viscosity was measured. Where the solvent
◎ if the content is 15% or less and paintable
◯: paintable at 30% or less, 40% or more from 30%
The ones that can be painted below are marked with △, and those with more than 40% are marked with ×.
Displayed. (3) Weather resistance The gloss of the coating film after being subjected to an accelerated weather resistance tester for 3000 hours.
The retention rate was measured. Here, the gloss retention rate is 85% or more.
◎, 70% or more and less than 85% ○, 70% not
The thing of fullness was expressed by X. (4) Scratch resistance Felt is impregnated with 5% of cleanser and 1 kg of load
After applying the weight and reciprocating 30 times, measure the gloss retention rate
Was. Here, if the gloss retention rate is 75% or more, ◎, 60
% Or more and less than 75% with ○, less than 60% with X
expressed. (5) Gasoline resistance Tilt the coated plate at 45 ° and put gasoline (Nisseki Silva
1) was poured and left to dry. This one cycle
After 10 cycles of the
Observed at. Here, those that do not change are ○, discoloration and class
The occurrence of the crack was marked as x. (6) Adhesion test Put a cross cut on each coated plate with a knife and put it in the
Adhesion test by sticking and peeling
Was. In this test, the one that showed adhesiveness is ○,
Those that are not marked with x. (7) Thermal cycle test After putting a cross cut on each coated plate with a knife,
Time, 1 hour at room temperature, 1 hour at -20 ° C, 1 hour at room temperature
10 cycles are repeated with 1 cycle as
The occurrence was confirmed. In this test,
Those that did not occur were indicated as ○, and those that did not occur were indicated as ×. (8) Chipping resistance Each coated plate was placed on a diamond shot tester at an angle of 20 °.
And then add 0.02 g of diamond to 200 at -20 ° C.
Collision at a speed of km / H and the peeling area (mm²)
It was measured. Where the peeling area is 1 mm²◎,
1mm²2 mm or more ²Less than ○, 2 mm²3 mm or more²Not yet
Full of △ △ 3mm²The above is indicated by x.Characteristic evaluation of clear paint

[0061]

[Table 16] Table 6 Weather resistance Scratch resistance Solvent content Gasoline resistance 25 ° C 60 ° C C1 ○ ○ ○ ◎ ○ C2 ○ ○ ○ ○ ○ C3 ○ ○ ○ ◎ ○ C4 ○ ○ ○ ○ ○ C5 ○ ○ ○ ◎ ○ C6 ○ ◎ △ ○ ○ C7 ○ ○ ○ ◎ ○ C8 ○ ○ ○ ○ ○ C9 ○ ○ ○ ◎ ○ C10 ○ ○ △ ○ ○ C11 ○ ○ ○ ◎ ○ C12 ○ ○ △ ○ ○ C13 ○ ○ ○ ◎ ○ C14 ○ ○ △ ○ ○ C15 ○ △ ○ ◎ ○ C16 ○ ○ △ △ ○ Comparative clear paint CH1 ○ ○ × △ ○ CH2 ○ ○ × × ○ CH3 × × ○ ◎ × CH4 × ○ ○ ◎ ○

Characteristic evaluation of solid color paint

[Table 17] Table 7 Weather resistance Scratch resistance Solvent content Gasoline resistance 25 ℃ 60 ℃ S1 ○ ○ ○ ◎ ○ S2 ○ ○ ○ ○ ○ S3 ○ ○ ○ ◎ ○ S4 ○ ○ ○ ○ ○ S5 ○ ○ ○ ◎ ○ S6 ○ ○ △ ○ ○ S7 ○ ○ ○ ◎ ○ S8 ○ ○ ○ ○ ○ S9 ○ ○ △ ○ ○ S10 ○ ○ △ ○ ○ S11 ○ ○ ○ ◎ ○ S12 ○ ○ △ ○ ○ S13 ○ ○ ○ ◎ ○ S14 ○ ○ △ ○ ○

Characteristic evaluation of base coat paint

[Table 18] Table 8 Chip resistance Water resistance Solvent content rate Cold heat Adhesion Pingability 25 ℃ 60 ℃ Curl B1 ○ ○ ○ ◎ ○ ○ B2 ○ ○ ○ ◎ ○ ○ B3 ○ ○ ○ ○ ○ ○ B4 ○ ○ ○ ◎ ○ ○ B5 ○ ○ △ ○ ○ ○ B6 ○ ○ ○ ◎ ○ ○ B7 ○ ○ ○ ○ ○ ○ B8 ○ ○ ○ ◎ ○ ○ B9 ○ ○ ○ ○ ○ B10 ○ ○ ○ ◎ ○ ○ B11 ○ ○ ○ ○ ○ B12 ○ ○ ○ ◎ ○ ○ B13 ○ ○ ○ ○ ○ ○

[0064]

As can be seen from the above table, when the acetoacetyl group-containing vinyl polymerized oligomer of the present invention is used,
25 ° C compared to the case of using the comparative acetoacetyl group-containing vinyl polymerized oligomer (H-1 to 3) in which the number average molecular weight, the weight average molecular weight or the weight average molecular weight / number average molecular weight ratio is not within the scope of the present invention. In spite of being able to make the limit amount of solvent that can be coated in 40% or less, scratch resistance, chipping resistance, water resistance, weather resistance of the obtained coating film,
Various coating film characteristics such as gasoline resistance can be improved. Further, even when compared with the conventionally proposed reaction system of vinyl polymerized oligomer containing acetoacetoxy group and compound (H-4) containing vinyl ether group, the coating material of the present invention is
A coating film having excellent weather resistance can be formed. Furthermore, since the coating composition of the present invention is of a low solvent type, it can greatly reduce the problem of air pollution due to volatilization of a large amount of organic solvent, and is a coating composition that is suitable for environmental problems.

Front page continuation (72) Inventor Hiroyuki Uemura 3-1, Fuchu-cho Shinchi, Aki-gun, Hiroshima Mazda Co., Ltd. (72) Inventor Kazuyo Koga 3-1-1 Shinchu, Fuchu-cho, Aki-gun, Hiroshima (72) ) Inventor Mika Osawa 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Motor Corporation

Claims (6)

[Claims] 1. An acetoacetyl group as an essential functional group of 0.
5 to 4.0 mol / kg resin content, total functional group 2.5 to
It is 4.0 mol / kg resin and has a number average molecular weight of 600.
˜1500 and a weight average molecular weight of 600 to 3000
And the weight average molecular weight / number average molecular weight is 1.0 to 2.
A vinyl polymerized oligomer which is 0, and a curing agent selected from an isocyanate prepolymer and a melamine resin, and an organic solvent amount of 0 to 40%.
A low-solvent type resin composition, wherein 2. An acetoacetyl group as an essential functional group of 0.
5 to 4.0 mol / kg resin content, total functional group 2.5 to
It is 4.0 mol / kg resin and has a number average molecular weight of 600.
˜1500 and a weight average molecular weight of 600 to 3000
And the weight average molecular weight / number average molecular weight is 1.0 to 2.
A low-solvent type coating composition comprising a vinyl polymerized oligomer of 0 and a curing agent composed of an isocyanate prepolymer and having an organic solvent amount of 0 to 40%. 3. An acetoacetyl group as an essential functional group of 0.
5 to 4.0 mol / kg resin content, total functional group 2.5 to
It is 4.0 mol / kg resin and has a number average molecular weight of 600.
˜1500 and a weight average molecular weight of 600 to 3000
And the weight average molecular weight / number average molecular weight is 1.0 to 2.
A vinyl polymerized oligomer of 0, a curing agent selected from an isocyanate prepolymer and a melamine resin, and a curing catalyst that catalyzes the reaction of the acetoacetyl group with the curing agent, and the amount of the organic solvent is 0. A low-solvent type coating composition, characterized in that it is -40%. 4. A low solvent type coating composition according to claim 2 or 3 is applied to the surface of an article to be coated and then heat-cured to form a coating film on the surface of the article to be coated. How to paint. 5. A method for coating the surface of an article to be coated with the low-solvent type coating composition according to claim 2 or 3, wherein the article to be coated is rotatably supported about a substantially horizontal axis. The coating is applied to the surface of the coating in a thickness that causes sagging on the surface that extends in the vertical direction, and then the coating is applied to the surface of the coating before the sagging occurs due to gravity. The coating is rotated at a speed such that the surface of the object to be coated shifts from a substantially vertical state to a substantially horizontal state before starting to rotate about the axis and at least before the rotation causes sagging of the applied coating due to gravity, and also due to centrifugal force due to rotation. A method for coating a low-solvent type coating composition, which comprises rotating the coating composition at a speed slower than the speed at which the sagging occurs. 6. A coating method, which comprises coating the surface of an article to be coated with the low solvent type coating composition according to claim 2 or 3 at 30 to 80 ° C.