JP3028627B2 - Paint finishing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel and useful paint finishing method. More specifically, the present invention provides, as an essential component, a thermosetting resin having a specific reactive functional group (reactive group) of 2-oxo-1,3-dioxolan-4-yl group in the molecule. The use of a one-pack type coating composition having excellent storage stability, comprising a one-component coating composition having excellent storage stability, and which is excellent in the appearance of a coating film such as acid resistance, weather resistance and smoothness. It relates to a forming method.

[0002]

2. Description of the Related Art In recent years, demands for excellent finished appearance have been particularly strong in the automobile industry.

However, conventionally, a clear coat which is a combination of a hydroxyl group-containing acrylic resin and a melamine-based curing agent, which is used as a top coating for automobiles,
There is a problem that the appearance is deteriorated due to acid rain.

[0004] In view of such a problem, development of a novel curing mode resin has been studied. Among them are 1)
A combination of a hydroxyl group-containing resin and a polyisocyanate,
2) a combination of a silanol group-containing resin and an epoxy group-containing resin, or 3) a combination of a hydroxyl group-containing resin and an acid anhydride group-containing resin, and 4) a moisture-curable type having a hydrolyzable silyl group. There is a resin system.

However, of the above resin systems, 1) a combination of a hydroxyl group-containing resin and a polyisocyanate has a short pot life and has a major drawback in terms of workability.
Further, in the case of 2) a combination of a silanol group-containing resin and an epoxy group-containing resin, and 4) in the case of a moisture-curable resin containing a hydrolyzable silyl group, a change in the degree of crosslinking of a coating film formed by baking over time Accordingly, there are various disadvantages such as a change in coating film performance and an unsatisfactory appearance.

[0006]

Further, in addition to such long-term storage stability and appearance of the coating film, it is possible to obtain a coating film which can withstand acid rain mainly in the automobile industry. Immediate development of useful curing systems
It has been strongly requested.

[0007] For this purpose, the present inventors have eagerly started research to meet the above-mentioned demands. In other words, the problem to be solved by the present invention is a one-pack type coating resin composition having excellent storage stability, and is extremely useful because it has excellent coating appearance such as acid resistance, weather resistance and smoothness. It is an object of the present invention to provide a specific coating finishing method, which can be called laminating coating, using a specific coating composition containing a thermosetting resin as an essential component.

[0008]

Means for Solving the Problems Accordingly, the present inventors have:
Focusing on the problem to be solved by the invention as described above, as a result of diligent and repeated studies, in forming a multilayer coating film by a two coat one bake method or a two coat two bake method, or an overcoat method, As a clear coat, 2-oxo-1,3-dioxolane-
By using a coating resin composition containing a thermosetting resin (A) having a 4-yl group as an essential base resin component and not containing a polyamine-based curing agent, storage stability is excellent, and thus workability is improved. The present invention provides a good one-pack type coating composition, and furthermore, it has been found that a coating film having not only acid resistance but also excellent weather resistance and coating film appearance can be obtained. Was.

That is, the present invention provides, as an essential component,
At least two general formulas in one molecule

[0010]

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Wherein R ₁ , R ₂ and R _{3 in the} formula
Represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. A one-pack type coating resin composition containing a thermosetting resin (A) having a 2-oxo-1,3-dioxolan-4-yl group represented by By using, 2
An object of the present invention is to provide a new and extremely useful coating finishing method of forming a laminated coating film by a coat 1 bake method, a 2-coat 2 bake method, or an overcoat method.

The term “laminated coating” refers to, for example, first applying a crosslinkable base coat paint in the form of a blend of a luminous agent and / or a color pigment on an object to be coated (substrate). A so-called two-coat one-bake coating method in which a thermosetting clear coat paint (clear paint I) is applied on the surface and crosslinked.
Alternatively, a coating method using a so-called three-coat two-bake method in which a thermosetting clear coat paint (clear paint II) is further applied on the thus-obtained laminated paint and crosslinked, or A base material) is coated with a crosslinkable base coat paint containing a brightener and / or a color pigment to form a cross-link, and then a thermosetting clear coat paint is applied on the base coat-coated surface to form a cross-link. It refers to various systems by a so-called two-coat two-bake coating method and the like, and therefore, in the present invention,
The term "laminated coating" refers to a coating obtained by the coating method as described above.

[0013] Here, first, the above-mentioned 2-oxo-1, which is used in carrying out the method of the present invention, is used.
The 3-dioxolan-4-yl group-containing thermosetting resin (A) may, of course, be dissolved or dispersed in an organic solvent, or may be once neutralized with a basic substance and then neutralized. It may be dissolved or dispersed in an aqueous medium, or may be dissolved or dispersed in an aqueous medium using a protective colloid and / or an emulsifier.

If only typical examples of the thermosetting resin (A) are given as examples, at least two of the general formulas per molecule may be used.

[0015]

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Wherein R ₁ , R ₂ and R _{3 in the} formula
Represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. A vinyl copolymer (a-1) having a 2-oxo-1,3-dioxolan-4-yl group represented by the formula:
Or at least two 2-oxo-1,3 in one molecule
A modified vinyl copolymer (a-3) having a dioxolan-4-yl group and at least two carboxyl groups and / or acid anhydride groups in one molecule.

If only one typical one-pack type coating resin composition referred to in the present invention is exemplified, the above-mentioned base resin components,
Vinyl copolymers (a-1) and modified vinyl copolymers (a
-3) and one or more of these 2-oxo-1,3-
A curing catalyst (b-1) for a dioxolan-4-yl group is blended, and some of them do not contain a polyamine-based curing agent, while others contain a vinyl copolymer (a-1) or a modified vinyl copolymer. There is a form in which a polymer (a-3) or the like is blended with one or more curing catalysts (b-1), and a polyamine-based curing agent is not contained.

Alternatively, a vinyl copolymer (a-1), a modified vinyl copolymer (a-3), etc.
One or more of the above curing catalysts (b-1) and a curing agent (c-1) having a functional group capable of reacting with a hydroxyl group are blended, and there is also a form in which a polyamine-based curing agent is not contained. Are a vinyl copolymer (a-1), a compound (a-2) having at least two carboxyl groups and / or acid anhydride groups in one molecule, and one or more curing catalysts (b
-1) and the above-mentioned hydroxyl-reactive curing agent (c-1), and a polyamine-based curing agent is not contained.

In the present invention, the term "aqueous medium" means water alone containing at least 10% by weight of water or a so-called mixed form (mixture) of this water and solvents. It is.

If only typical solvents other than water, which are constituents of the aqueous medium, are exemplified, methyl alcohol, ethyl alcohol,
Various alcohols represented by butyl alcohol or butyl cellosolve;

Various ketones represented by methyl ethyl ketone or methyl isobutyl ketone; alkyl esters of various organic carboxylic acids represented by ethyl acetate or amyl acetate; represented by toluene, xylene or “Solvesso 100” Aromatic hydrocarbons; or high-boiling polar solvents represented by n-methylpyrrolidone.

Here, the above vinyl copolymer (a-1) having at least two 2-oxo-1,3-dioxolan-4-yl groups in one molecule, and at least two vinyl copolymers in one molecule As a method for preparing a modified vinyl copolymer (a-3) having a 2-oxo-1,3-dioxolan-4-yl group and at least two carboxyl groups and / or acid anhydride groups,

For example, one polymerizable unsaturated double bond (hereinafter also referred to as a polymerizable unsaturated group) per molecule and at least one 2-oxo-1,3-dioxolan-4 And a polymer having a polymerizable unsaturated group and a monomer having another polymerizable unsaturated group in a conventional manner. Alternatively, a compound having a 2-yl group, such as glyceryl carbonate, may be used. There is also a method in which a compound having both an oxo-1,3-dioxolan-4-yl group and a hydroxyl group is subjected to an addition reaction with a vinyl copolymer having a functional group capable of reacting with the hydroxyl group. During,
The method described above is preferable because it is simple.

Here, only typical functional groups capable of reacting with the above-mentioned hydroxyl groups are exemplified, and examples thereof include an isocyanate group, an acid anhydride group and an acid chloride group.

In the above-mentioned molecule, at least two 2-
Used in obtaining a vinyl copolymer (a-1) having an oxo-1,3-dioxolan-4-yl group,
A compound having one polymerizable unsaturated group and at least one 2-oxo-1,3-dioxolan-4-yl group in one molecule is represented by the general formula:

[0026]

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Wherein R ₁ , R ₂ , R ₃ and R ₄ in the formula each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. And ] Is indicated.

As typical examples of such compounds, only typical examples are 2,3-carbonatepropyl (meth) acrylate, 3,4-carbonatebutyl (meth) acrylate, and 4,5-carbonatepentyl (meth) acrylate. Acrylate, 6,7-carbonate hexyl (meth) acrylate, 2,3-carbonate propyl vinyl ether or methyl-2,3-carbonate propyl crotonate.

The amount of the compound used is as follows:
1 to 70 parts by weight, preferably 5 to 50 parts by weight is appropriate. If the amount is less than 1 part by weight, the cross-linking becomes insufficient when forming the coating film.
Sufficient coating performance cannot be exhibited, while 70
When the amount exceeds the weight part, a hard and brittle coating film is liable to be formed, so that any case is not preferable.

Further, a compound having both the polymerizable unsaturated group and a 2-oxo-1,3-dioxolan-4-yl group (hereinafter, also referred to as a cyclocarbonate group) (hereinafter, a cyclocarbonate group-containing compound). Other unsaturated monomers that can be copolymerized with
Although not particularly limited, the use of unsaturated monomers having a hydroxyl group or a carboxyl group as a functional group is particularly preferable because the effects of the present invention can be further enhanced.

If only typical examples of such hydroxyl group-containing unsaturated monomers are given below, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate or 3-hydroxypropyl (meth) ) Hydroxyalkyl (meth) acrylates such as acrylate, 4-hydroxybutyl (meth) acrylate;

Hydroxyalkyl vinyl ethers such as 2-hydroxyethyl vinyl ether or 4-hydroxyalkyl vinyl ether; or allyl compounds such as allyl alcohol or hydroxyethyl allyl ether;

Alternatively, “Placcel FM or F
A monomers "(caprolactone-added monomers manufactured by Daicel Chemical Co., Ltd.), and further, compounds obtained by subjecting various monomers to the addition reaction of ε-caprolactone, and the like. is there.

Thus, the introduction of the hydroxyl group causes a reaction with the cyclocarbonate group, thereby increasing the crosslink density, and thereby improving the solvent resistance and weather resistance.

Further, the combined use with a curing agent having a functional group capable of reacting with a hydroxyl group can further improve the crosslink density. If only typical examples of such a curing agent are given, examples thereof include alkyl etherified melamine resins and blocked isocyanate compounds.

If only typical examples of the above-mentioned unsaturated monomers containing a carboxyl group are given, only ethylenically unsaturated monomers such as (meth) acrylic acid, maleic acid, fumaric acid and itaconic acid can be mentioned. Mono- or dicarboxylic acids; monoesters of an ethylenically unsaturated dicarboxylic acid such as monoethyl maleate, monobutyl maleate, monobutyl fumarate or monoethyl itaconate with a saturated monohydric alcohol having 1 to 4 carbon atoms (half Esters);

Or a compound obtained by adding an acid anhydride such as phthalic anhydride to a hydroxyl group-containing vinyl monomer such as 2-hydroxyethyl (meth) acrylate.

Thus, by using the carboxyl group-containing monomer, the compound having at least two carboxyl groups and / or acid anhydride groups in one molecule (a-
Since the compatibility with 2) will be significantly improved,
Such a means is particularly effective and, of course, can also react with the cyclocarbonate group, so that the crosslink density can be increased.

Having a copolymerizability with a cyclocarbonate group-containing unsaturated monomer other than these carboxyl group-containing unsaturated monomers or acid anhydride group-containing unsaturated monomers;
If only typical representative examples of various unsaturated monomers are given, alkyl (meth) acrylates having an alkyl group having 1 to 22 carbon atoms, 2-ethoxyethyl (meth) acrylate, etc. Various acrylates such as cyclohexyl (meth) acrylate or benzyl (meth) acrylate;

Various cyano group-containing vinyl monomers such as (meth) acrylonitrile; various epoxy group-containing monomers such as glycidyl (meth) acrylate or methyl glycidyl (meth) acrylate; (meth) acrylamide, N-alkoxy Various nitrogen-containing monomers such as methyl (meth) acrylamide or dimethylaminoethyl (meth) acrylate; phosphoric acid group-containing monomers such as mono- [2- (meth) acryloyloxyethyl] acid phosphate;

Various hydrolyzable silyl group-containing monomers such as γ- (meth) acryloyloxypropyltrimethoxysilane; various vinyl ethers such as ethyl vinyl ether, isobutyl vinyl ether or cyclohexyl vinyl ether; styrene, tert-butylstyrene Various aromatic vinyl monomers such as, α-methylstyrene or vinyltoluene;

Various fluorinated vinyl monomers such as tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, vinyl fluoride or vinylidene fluoride; or vinyl acetate, vinyl propionate or "Veoba" (Netherlands) And various vinyl esters such as a branched saturated aliphatic monocarboxylic acid vinyl ester manufactured by Kokuchi Shell Co., Ltd.

The cyclocarbonate group-containing vinyl copolymer (a-1) may be prepared by a conventional method such as a solution polymerization method or a non-aqueous dispersion polymerization method.
The simplest is the solution radical polymerization method.

If only typical solvents used here are exemplified, toluene, xylene, cyclohexane, n-hexane, octane, "Solvesso 100 or 150" (Exxon, USA)
Various hydrocarbon solvents such as aromatic hydrocarbon solvents manufactured by Chemical Co., Ltd.) or "LOWS" (mixed solvents of aliphatic and aromatic hydrocarbons manufactured by Shell Co.);

Various ester solvents such as methyl acetate, butyl acetate, amyl acetate, ethyl ethoxypropionate or ethoxypropionate acetate;
Or various alcohol solvents such as sec-butyl alcohol or butyl cellosolve; or various ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone or cyclohexanone. These may be used alone or in combination of two or more. It goes without saying that they may be used in combination.

In addition, if only typical radical polymerization initiators are exemplified, azo compounds represented by azobisisobutyronitrile and peroxides represented by benzoyl peroxide are exemplified. System.

Further, if necessary, lauryl mercaptan, octyl mercaptan, 2
-Mercaptoethanol, octyl thioglycolate,
Various chain transfer agents such as 3-mercaptopropionic acid or α-methylstyrene dimer can be used.

The vinyl copolymer (a-
The number average molecular weight of 1) is preferably in the range of 800 to 50,000 in terms of coating workability and various properties of the coating film.

Next, the compound (a) having at least two carboxyl groups and / or acid anhydride groups in one molecule, which is used in carrying out the method of the present invention.
If only typical ones are exemplified as -2), vinyl copolymers having a carboxyl group and / or an acid anhydride group, polyester resins, low molecular weight compounds and the like can be mentioned.

Among them, first, as a vinyl polymer having a carboxyl group and / or an acid anhydride group, a carboxyl group-containing monomer and / or an acid anhydride group-containing monomer can be prepared by various methods as described above. Those obtained by copolymerization with copolymerizable unsaturated monomers may be used.

The carboxyl group-containing monomer includes, of course, the various compounds described above. In addition, if only typical examples of the acid anhydride group-containing monomer are given as examples, those having both an acid anhydride group and a polymerizable unsaturated group, such as maleic anhydride and itaconic anhydride. Needless to say,

Next, the carboxyl group-containing polyester resins may be those obtained by reacting an acid component excessively with an alcohol component (polyhydric alcohols) by a conventional method, or It may be obtained by subjecting a hydroxyl group-containing polyester resin to a ring-opening addition reaction of an acid anhydride group-containing compound.

Specific examples of such polyester resins include polycarboxylic acids represented by phthalic acid, hexahydrophthalic acid, isophthalic acid, adipic acid, maleic acid and dimer acid; ethylene glycol and propylene glycol. Particularly typical examples include those obtained by subjecting a polyhydric alcohol represented by neopentyl glycol or trimethylolpropane to a condensation reaction by a conventional method.

Further, a compound obtained by adding an acid anhydride group-containing compound represented by trimellitic acid or the like to a hydroxyl group in such a polyester resin may be used, or a polyvalent carboxylic acid may be used. It may be obtained by reacting under excessive conditions.

The carboxyl group-containing low molecular weight compound includes polycarboxylic acids represented by phthalic acid, isophthalic acid, adipic acid or dimer acid. It is not particularly limited as long as it has a carboxyl group.

On the other hand, only typical examples of the acid anhydride group-containing low molecular weight compounds will be given below. Trimellitic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexetic anhydride, hymic anhydride, maleic anhydride, maleic anhydride Acid, itaconic anhydride, pyromellitic anhydride, glycerol tris (trimellitate) or ethylene glycol di (trimellitate).

Next, the curing catalyst (b-1) for the above-mentioned cyclocarbonate group will be described. In the present invention, the curing catalyst (b-1) is used to remove the carbon dioxide from the cyclocarbonate group. Although it is a particularly important component for the reaction, tetramethylammonium fluoride, trimethylbenzylammonium hydroxide, 2-hydroxypyridine or trimethylbenzylammonium methoxide may be mentioned only to exemplify particularly typical ones among them. Various 4 like
Quaternary ammonium salts;

Alternatively, various acid catalysts such as phosphoric acid, p-toluenesulfonic acid or dimethyl sulfate, etc.
Further, there are various carbonates such as calcium carbonate.

The curing catalyst is used in an amount of 10% of the solid content of the vinyl copolymer (a-1).
The range of 0.05 to 60 mmol per 0 parts by weight is appropriate.

For example, the amount used is 120 to 16
When baking is performed for 20 minutes in a temperature range of 0 ° C., if the amount is less than 0.05 mmol,
If the cross-linking reaction cannot proceed sufficiently, but if it is used in too large a quantity exceeding 60 mmol, it will cause considerable problems in the storage stability of the paint, and the water resistance of the cured coating film In any case, it is not preferable because the properties are deteriorated.

Of the various thermosetting resins (A) described above, a coating composition in the form of being dissolved or dispersed in an aqueous medium will be described. To exemplify only typical examples belonging to such a class, first, at least two 2-oxo-1,3-dioxolan-4-yl groups in one molecule;
Modified vinyl copolymer having at least two carboxyl groups and / or acid anhydride groups in one molecule (a-
3) neutralized with a basic substance and obtained by dissolving or dispersing it in the various aqueous media described above, that is, an aqueous modified vinyl copolymer [hereinafter, referred to as
It is also referred to as an aqueous modified vinyl copolymer (a-4). ]

Then, the above-mentioned aqueous-modified vinyl copolymer (a-4) and one or more curing catalysts for cyclocarbonate groups (b-1) are dissolved or dispersed in an aqueous medium. A so-called water-based curing catalyst [hereinafter also referred to as a water-based curing catalyst (b-2)]. ]

The modified vinyl copolymer (a-3) having at least two cyclocarbonate groups in one molecule and at least two carboxyl groups and / or acid anhydride groups in one molecule is converted to a basic compound. A vinyl copolymer obtained by neutralizing with a substance and a curing agent (c-1) having a functional group capable of reacting with the above-mentioned hydroxyl group, that is, a hydroxyl-reactive curing agent is dissolved or dispersed in an aqueous medium. The so-called aqueous hardening agent (c-2) [hereinafter, also referred to as an aqueous hardening agent (c-2)]. Is obtained by blending

Alternatively, a modified vinyl copolymer (a-3) having at least two cyclocarbonate groups in one molecule and at least two carboxyl groups and / or acid anhydride groups in one molecule is converted to a basic compound. A vinyl copolymer obtained by neutralization with a substance, and the aqueous curing catalyst (b) described above.
-2) and the above-mentioned aqueous curing agent (c-2).

As described above, various methods of preparing the thermosetting resins (A) dissolved or dispersed in the aqueous medium include the vinyl copolymers (a-
Examples of the method for dissolving or dispersing 1) or the modified vinyl copolymer (a-3) in an aqueous medium include the following.

That is, (1) the modified vinyl copolymer (a
-3) is obtained by dissolving or dispersing a neutralized product obtained by neutralizing the product with a basic substance in an aqueous medium.

(2) A cyclocarbonate group-containing vinyl monomer and another polymerizable unsaturated monomer copolymerizable with the monomer are mixed with a protective colloid and / or an emulsifier. And the vinyl copolymer (a-1) thus obtained is dissolved or dispersed in an aqueous medium.

(3) There is also a method of adding a protective colloid and / or an emulsifier to the vinyl copolymer (a-1) and dissolving or dispersing the same in an aqueous medium. Here, only typical representative examples of basic substances include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide; sodium carbonate, potassium carbonate, sodium hydrogen carbonate and carbonate. Carbonates or bicarbonates such as potassium hydrogen;

Trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, dimethylcyclohexylamine, dimethylbenzylamine, dimethylethanolamine, diethanolamine,
Various amines such as 1-dimethylamino-2-propanol or N-methylmorpholine; and ammonia, etc. Among them, from the viewpoints of water resistance and chemical resistance of the coating film, the use of amines is particularly important. desirable.

The amount of the base to be added is appropriately determined depending on the amount of the carboxyl group introduced into the vinyl copolymer (a-1).
It should be understood that the amount required to neutralize 30 to 100% of the carboxyl groups therein.

The neutralized product thus obtained can be dissolved or dispersed in an aqueous medium by thoroughly stirring the mixture of the neutralized product and the aqueous medium. If necessary, a part or all of the organic solvent may be removed by distillation.

As the above-mentioned protective colloid, known and commonly used ones can be used as they are, but if only typical representative ones are exemplified, polycarboxylic acid-based high molecular weight compounds may be used. Examples thereof include those in the form neutralized with a basic substance as described above, or high molecular weight substances having a polyoxyethylene chain; polyvinyl ethers; polyvinyl pyrrolidones; and hydroxyalkyl celluloses.

On the other hand, the above-mentioned emulsifier is not particularly limited, and any known and commonly used emulsifier can be used as it is. Nonionics such as ethylene nonyl phenyl ether or polyoxyethylene styrenated phenyl ether;

Polyamines of polyoxyethylene alkyl sulfate, polyoxyethylene alkyl phenyl sulfate, alkyl sulfate, alkane sulfate, alkylbenzene sulfonate, dialkyl sulfosuccinate, styrene sulfonate or vinyl sulfonate, or Anionic compounds such as sodium or -metal salts such as potassium.

At least one compound selected from such protective colloids and / or emulsifiers is made to exist in an aqueous medium, and is dissolved or dispersed in the aqueous medium by radical polymerization, redox polymerization or the like by a conventional method. A vinyl copolymer (a-1) in the form can be obtained.

Further, the above-mentioned protective colloid and / or emulsifier can be combined with the vinyl copolymer (a-1). As a means for such bonding, a protective colloid and / or an emulsifier itself having a polymerizable unsaturated group may be used, or a protective colloid and / or an emulsifier and a vinyl copolymer (a-1) may be used. And the like) are provided with functional groups (reactive groups) that can react with each other, and the reaction is performed through the reaction between the respective reactive groups.

The combination of the functional groups (reactive groups) which can react with each other is not particularly limited, but if only typical ones among them are exemplified, the COOH group may be used. / Cyclocarbonate group, amino group / cyclocarbonate group, hydroxyl group / acid anhydride group or hydrolyzable silyl group / hydrolyzable silyl group type.

As described above, the vinyl copolymer (a-
In the case where the method of adding a protective colloid and / or an emulsifier to 1) and dissolving or dispersing the same in an aqueous medium is adopted, the vinyl copolymer (a-1) previously prepared in a solution and the protective colloid may be used. The emulsifier and / or the emulsifier may be stirred together. In this case, if necessary, part or all of the organic solvent may be removed by distillation.

The coating composition thus obtained may be blended with known and commonly used additives such as leveling agents or ultraviolet absorbers, plasticizers, etc., and various resins such as polyester resins. I can do it.

Further, in the present invention, in forming a laminated coating film by a two-coat one-bake system or a two-coat two-bake system, and further by an overcoat system, a clear coat has been described above. Various cyclocarbonate group-containing thermosetting resins (A)
And a one-pack type coating composition containing the cyclocarbonate group-containing thermosetting resin (A) as an essential base resin component and not containing a polyamine-based curing agent.

In carrying out the coating finishing method of the present invention, a coating composition for a base coat includes:
It is not particularly limited as long as it can form a coating film, but if only a typical one among them is exemplified, the composition of a hydroxyl group-containing resin and a melamine resin Product, composition of hydroxyl group-containing resin and polyisocyanate compound, composition of hydroxyl group-containing resin and block polyisocyanate compound, composition of carboxyl group-containing resin and epoxy group-containing resin, or hydrolyzed silyl group It is a resin-containing resin, or a combination of two or more of these, and further, a form in which at least one kind of an organic pigment, an inorganic pigment, or a metal pigment is blended.

[0082]

Next, the present invention will be described more specifically with reference examples, examples and comparative examples.

In the following, all parts and percentages are by weight unless otherwise specified. Reference example 1
[Cyclocarbonate group-containing vinyl copolymer (a-1)
Preparation Example] 500 parts of xylene and 300 parts of n-butanol were charged into a four-necked flask equipped with a thermometer, a cooling pipe, a stirrer, and a nitrogen gas introducing pipe, and the temperature was raised to 120 ° C. 300 parts of carbonate propyl methacrylate, 200 parts of methyl methacrylate, 200 parts of styrene and 300 parts of n-butyl methacrylate
Parts of xylene, 200 parts of xylene, 10 parts of azobisisobutyronitrile (AIBN) and tert
-Butyl peroxy-2-ethylhexanoate 20
Part of the mixture was added dropwise over 5 hours. After completion of the addition, the mixture was maintained at the same temperature for 7 hours to continue the reaction. The mixture had a nonvolatile content of 50.4% and a Gardner viscosity at 25 ° C. (hereinafter referred to as “viscosity”). Is abbreviated as M.N), and a solution of the target copolymer having a number average molecular weight of 11,000 was obtained.
Hereinafter, this is abbreviated as resin (a-1-1).

Reference Example 2 (same as above)
250 parts of 2,3-carbonate butyl acrylate,
150 parts of styrene, 3 parts of isobutyl methacrylate
50 parts, 150 of 2-ethylhexyl methacrylate
In the same manner as in Reference Example 1 except that a mixture consisting of 50 parts of 4-hydroxybutyl methacrylate and 50 parts of methacrylic acid was used.
A 0.6% solution of the target copolymer having a viscosity of Z was obtained. Hereinafter, this is abbreviated as resin (a-1-2).

Reference Example 3 [Preparation Example of Carboxyl Group-Containing Vinyl Resin (a-2)] As a monomer mixture, 300 parts of acrylic acid, 300 parts of styrene and 400 parts of n-butyl methacrylate were used. , 15 parts of AIBN and tert-butyl par 2-
Non-volatile content was 50.2% in the same manner as in Reference Example 1 except that 70 parts of ethylhexanoate was changed to be used.
And a solution of a resin having a viscosity of O was obtained. Hereinafter, this is abbreviated as resin (a-2-1).

Reference Example 4 [Preparation Example of Carboxyl Group-Containing Polyester Resin (a-2)] "Placcel 308"
[Caprolactone polymerized polio produced by Daicel Chemical Industries, Ltd.
To 85 parts of phthalic anhydride, 100 parts of xylene and 50 parts of butyl acetate, and reacted at 120 ° C. for 2 hours to obtain a non-volatile content of 80%. In addition, a resin solution having a viscosity of Q was obtained. Hereinafter, this is abbreviated as resin (a-2-2).

Reference Example 5 [Preparation example of aqueous neutralized product of vinyl copolymer (a-3) having both a cyclocarbonate group and a carboxyl group] In the same reaction vessel as in Reference Example 1, 66 The temperature was raised to 80 ° C. under a nitrogen atmosphere. Here, 30 parts of methyl methacrylate and 30 parts of n-butyl methacrylate
A mixture consisting of 12 parts of n-butyl acrylate, 20 parts of 4-methacryloyloxymethyl-1,3-dioxolan-2-one, 8 parts of acrylic acid and 2 parts of tert-butyl per-2-ethylhexanoate. Was added dropwise over 3 hours.

After completion of the dropwise addition, the mixture is kept at the same temperature for 10 hours to obtain a non-volatile content of 60%, a number average molecular weight of 19,000 and a molecule having a cyclocarbonate group and a carboxyl group in one molecule. Vinyl copolymer (a-3)
Was obtained. Next, 11.2 parts of triethylamine and 44.2 parts of isopropyl alcohol were added to the polymer solution thus obtained, and the mixture was sufficiently stirred to remove the polymer solution in which 100% of carboxyl groups had been neutralized. Obtained.
Hereinafter, this is abbreviated as modified vinyl copolymer (a-3-1).

Thereafter, the whole amount of the modified vinyl copolymer (a-3-1) was added while sufficiently stirring 148.3 parts of water to form a uniform solution. Further, a part of isopropyl alcohol was removed from this solution under reduced pressure to obtain an aqueous composition having a nonvolatile content of 40%. Hereinafter, this is abbreviated as aqueous modified vinyl copolymer (a-4-1).

Reference Example 6 (same as above) In a reaction vessel similar to Reference Example 1, 130 parts of deionized water and "Latteum S-1"
80 "(a reactive emulsifier manufactured by Kao Corporation) and heated to 80 ° C under a nitrogen atmosphere.

There, 30 parts of methyl methacrylate,
35 parts of n-butyl methacrylate, 15 parts of n-butyl acrylate, 4-methacryloyloxymethyl-
15 parts of 1,3-dioxolan-2-one and 5 parts of methacrylic acid, 0.4 part of “Levenol WZ”, 0.5 part of “Hytenol N-08” and 20 parts of deionized water And 1 part of ammonium peroxide and 20 parts of deionized water were added dropwise over 3 hours.

After completion of the dropping, the temperature was maintained at the same temperature for 1 hour, and the pH was adjusted to 7 with diethanolamine.
An aqueous composition having a nonvolatile content of 40% was obtained. Hereinafter, this is abbreviated as aqueous modified vinyl copolymer (a-4-2).

REFERENCE EXAMPLE 7 (same as above) A reaction vessel similar to that of Reference Example 1 was charged with 66 parts of methyl ethyl ketone and heated to 80 ° C. under a nitrogen atmosphere.

There, 20 parts of methyl methacrylate,
10 parts of styrene, 30 parts of n-butyl methacrylate
Parts, 17 parts of n-butyl acrylate, 1 part of γ-methacryloyloxypropyltrimethoxysilane, 4-methacryloyloxymethyl-1,3-dioxolan-2
20 parts of -one and 5 parts of acrylic acid and tert-
A mixture consisting of 2 parts of butyl per-2-ethylhexanoate was added dropwise over 3 hours.

After completion of the dropwise addition, the mixture is kept at the same temperature for 10 hours to obtain a nonvolatile content of 60% and a number average molecular weight of 20,000, which has both a cyclocarbonate group and a carboxyl group in one molecule. A solution of a vinyl copolymer was obtained.

Next, 30 parts of "Primal ASE-60" (a polycarboxylic acid emulsion manufactured by Nippon Acrylic Chemicals Co., Ltd.) was added to the copolymer solution thus obtained, and diethanolamine was added to adjust the pH to 8. .
3, 150 parts of deionized water was added with sufficient stirring to form a uniform solution.

Thereafter, a part of methyl ethyl ketone was removed under reduced pressure to obtain an aqueous composition having a nonvolatile content of 40%. Hereinafter, this is converted to an aqueous modified vinyl copolymer (a-
Abbreviated as 4-3).

Examples 1 to 9 and Comparative Example 1 Using the respective resins obtained in Reference Examples 1 to 7,
According to the composition ratio shown in the table, a coating composition used in carrying out the method of the present invention was obtained.

Further, when the thus obtained coating composition was used as a top coat, the performance of the coating film obtained through two-coat two-bake or two-coat two-bake finishing was evaluated.

The results are shown in the same table. In addition, Comparative Example 1 includes “Acrydic 52-748” (a hydroxyl group-containing acrylic resin manufactured by Dainippon Ink and Chemicals, Inc.)
The so-called acrylic resin / super resin obtained by blending “Super Beckamine L-117-60” (butyl etherified melamine resin manufactured by the same company) in a ratio such that the weight ratio of the former to the latter is 70:30. It uses a melamine resin-based baking paint.

As base paints A, “Acrydic 47-712” (a hydroxyl group-containing acrylic resin manufactured by the same company) and “Super Beckamine L-117-6” are used.
0 "and" aluminum paste 7160NS "[aluminum paste manufactured by Toyo Aluminum Co., Ltd.], which is a so-called metallic base paint.

As the base paint B, “Beccolite”
GF-542 "(a hydroxyl group-containing polyester resin manufactured by Dainippon Ink and Chemicals, Inc.) and" Super Beckamine
L-117-60 "and carbon black, and has a PWC of 30%.

As base paint C, styrene: methyl methacrylate: n-butyl acrylate: methacrylic acid: 2-hydroxypropyl methacrylate = 10: 4
A hydroxyl group-containing vinyl copolymer emulsion having a composition of 0: 43: 2: 5 (weight ratio) and a non-volatile content of 40%, and "Cymel C-325" [methyl etherification manufactured by Mitsui Cyanamid Co., Ltd.] Melamine resin], "Primal ASE-60", and "Aluminum paste WZ7
160 ”[Aluminum manufactured by Toyo Aluminum Co., Ltd.
Paste), and the so-called metallic
It uses base paint,

As the base paint D, the resin (a-1-1) obtained in Reference Example 1 and the resin (a-a) obtained in Reference Example 3 were used.
-2-1) and trimethylbenzylammonium hydroxide were used in the same manner as in Example 1, and a so-called metallic base paint obtained using "Aluminum paste 7160NS" was used.

Further, Example 4 was a case where the two-coat two-bake finishing method was used, and in all other cases, the coating film was formed by the two-coat one-bake finishing method. The baking conditions are all at 140 ° C. for 20 minutes.

[0106]

[Table 1]

[0107]

[Table 2]

[0108]

According to the coating finishing method of the present invention, a one-pack type coating composition is used because the curable resin composition having excellent storage stability and therefore good workability is used. A coating film having excellent acid resistance, weather resistance, and appearance of the coating film, particularly, excellent smoothness can be provided.

Therefore, the paint finishing method of the present invention
For example, it can be said that this is one that opens up new innovations as an automotive paint finishing method.

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C09D 133/10 B05D 1/36 B05D 7/24 C08F 220/28 CA (STN) CAOLD (STN) REGISTRY (STN )

Claims (9)

(57) [Claims] 1. Two-coat one-bake method or two-coat two
Bake system or, in forming a multilayer coating film with an overcoat method, as clearcoat, 2-oxo-1 in the molecule, 3 - thermosetting resins having a dioxolan-4-yl group (A) is required base as a resin component <br/> seen including, characterized by using a one-pack type coating resin composition not containing the polyamine-based curing agent, paint finishing method of. Wherein said the in the molecule 2-oxo-1, 3 -
The coating finishing method according to claim 1, wherein the thermosetting resin (A) having a dioxolan-4-yl group is dissolved or dispersed in an organic solvent. Wherein the the in the molecule 2-oxo-1, 3 -
The coating finishing method according to claim 1, wherein the thermosetting resin (A) having a dioxolan-4-yl group is dissolved or dispersed in an aqueous medium. 4. The one-pack type coating resin composition for a clear coat according to claim 1, wherein at least two general formulas per molecule are used. Wherein R ₁ , R ₂ and R ₃ are each
It represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. To the vinyl copolymer (a-1) having a 2-oxo-1,3-dioxolan-4-yl group represented by the formula
3. A curing catalyst (b-1) containing a -oxo-1,3-dioxolan-4-yl group curing catalyst.
Or the paint finishing method according to 3 . 5. The resin composition for a one-part coating composition for a clear coat according to claim 1, wherein at least two general formulas per molecule are used. Wherein R ₁ , R ₂ and R ₃ are each
It represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. The vinyl copolymer (a-1) containing a 2-oxo-1,3-dioxolan-4-yl group represented by the formula (1) has at least two carboxyl groups and / or acid anhydride groups in one molecule. Compound (a-2) and one or more 2-oxo-1,3-dioxolan-4-yl group curing catalyst (b-
The compound according to claim 1 , 2 or 3, wherein
3. The paint finishing method according to 3 . 6. The resin composition of claim 1, wherein the one-pack type resin composition for a clear coat has at least two components per molecule. Wherein R ₁ , R ₂ and R ₃ are each
It represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. ] And 2-oxo-1,3-dioxolan-4-yl group represented by the modified vinyl copolymer have a at least two carboxyl groups and / or acid anhydride groups in (a-3),
One or more curing catalysts (b-1) for a 2-oxo-1,3-dioxolan-4-yl group are compounded.
The coating finishing method according to claim 1 , 2 or 3 . 7. The one-pack type resin composition for clear coat described above, wherein at least two general formulas per molecule are represented by the following formula: Wherein R ₁ , R ₂ and R ₃ are each
It represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. To the vinyl copolymer (a-1) having a 2-oxo-1,3-dioxolan-4-yl group represented by the formula
The composition according to claim 1, wherein a curing catalyst (b-1) of a -oxo-1,3-dioxolan-4-yl group and a curing agent (c-1) having a functional group capable of reacting with a hydroxyl group are blended. The coating finishing method according to 1 , 2, or 3 . 8. The resin composition for a one-pack type clear coat coating composition according to claim 1, wherein at least two general formulas per molecule are used. Wherein R ₁ , R ₂ and R ₃ are each
It represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. The vinyl copolymer (a-1) containing a 2-oxo-1,3-dioxolan-4-yl group represented by the formula (1) has at least two carboxyl groups and / or acid anhydride groups in one molecule. Compound (a-2) and one or more 2-oxo-1,3-dioxolan-4-yl group curing catalyst (b-
The composition according to claim 1 , wherein 1) and a curing agent (c-1) having a functional group capable of reacting with a hydroxyl group are blended.
Or the paint finishing method according to 3 . 9. The resin composition according to claim 1, wherein said one-pack type coating resin composition for a clear coat has at least two components per molecule. Wherein R ₁ , R ₂ and R ₃ are each
It represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. ] And 2-oxo-1,3-dioxolan-4-yl group represented by the modified vinyl copolymer have a at least two carboxyl groups and / or acid anhydride groups in (a-3),
A compound obtained by mixing one or more curing catalysts of 2-oxo-1,3-dioxolan-4-yl group (b-1) and a curing agent (c-1) having a functional group capable of reacting with a hydroxyl group. The method according to claim 1 , 2, or 3 , wherein