JP3148407B2 - High solid content resin composition, high solid content type paint using the same, and coating and baking method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a novel and useful high solid content resin composition, a high solid content type paint using the same,
The present invention relates to a method for applying and baking paint. More particularly, the present invention provides, in part, a high acrylic resin composition comprising a specific acrylic oligomer having blocked hydroxyl groups, a hydroxyl reactive curing agent, and a dissociation or curing catalyst. A high-solids type paint; two-parts, a high-solids resin composition and a high-solids content mainly comprising a low-viscosity acrylic oligomer obtained by blocking a hydroxyl group with a specific compound thus obtained. When coating and baking the mold paint, the object to be coated is rotated around a substantially horizontal axis so that no sagging occurs, so that one coat and one bake (hereinafter abbreviated as "1C-1B") and two coats. 1 bake (hereinafter abbreviated as “2C-1B”), 2 coats 2 bake (hereinafter abbreviated as “2C-2B”), 3 coats 2 bake (hereinafter abbreviated as “3C-2B”). ) And Oh In bar coating system, and to a painting and baking method of the resin composition and coating.

[0002]

2. Description of the Related Art In recent years, in automotive exterior panel coating, a 2C-1B finish line coating is performed in the form of a combination of an acrylic polyol and a melamine resin. A large amount of solvent is released into the atmosphere from this painting line,
Moreover, by burning this discharged solvent,
There was a problem that the global warming phenomenon caused by the generation of a large amount of carbon dioxide would be accelerated. Investigations on water-based treatment have been widely conducted mainly on base coats. The clear coat is required to have a high appearance and various coating properties such as durability. Water-based paint, powder paint,
Although UV-curable paints and the like are also being widely studied, it can be said that reducing the solvent of conventional resins is the shortest route.

However, when the molecular weight of the conventional acrylic polyol-melamine resin combination is reduced to achieve high solid differentiation, the content of hydroxyl groups must be increased in order to compensate for insufficient curing. By this means, it is not always possible to achieve a low viscosity, and, furthermore, a coating film obtained by curing a resin having a high hydroxyl value with a melamine resin has an extremely low acid resistance. Invite you. In addition, at the time of coating, there is an inconvenience that dripping of the vertical surface due to the reduction in viscosity is remarkable.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned various problems in the prior art, to realize a reduction in viscosity, an improvement in acid resistance, and an improvement in scratch resistance, and to provide an armpit or a brush. It is an object of the present invention to provide a resin composition that does not cause sagging, and to provide an extremely useful coating method and baking method in which such various properties and characteristics are improved.

[0005]

The inventors of the present invention have conducted intensive studies in accordance with the objects of the present invention as described above. It has been found that it is performed by a method such as lowering the transition temperature.

That is, in order to reduce the polarity of a low-molecular-weight acrylic resin, the present inventors have proposed a method in which a hydroxyl group is blocked with a specific blocking agent and has a molecular weight of 1,500 or less and a hydroxyl group after dissociation. The concentration is 2.2 mol / 1,0
An acrylic oligomer (a) that is not less than 00 g;
By using a specific high solids resin composition comprising a curing agent (b) reactive with hydroxyl groups and a dissociation or curing catalyst (c), and a high solids type paint,
The present inventors have found that a coating film having low viscosity and free from cracks and sagging can be finished, and the present invention has been completed.

That is, the present invention relates to an acrylic oligomer (a) having a blocked hydroxyl group, a number average molecular weight of 1,500 or less, and a hydroxyl group concentration after dissociation of 2.2 mol / 1,000 g or more. ), A curing agent (b) having reactivity with a hydroxyl group, and a dissociation catalyst or a curing catalyst (c),
Xylene / n-butyl acetate
Chill (weight ratio = 60/40) mixed solvent with viscosity 150
Non-volatile content when diluted to cps is 74.5% or more
An object of the present invention is to provide a certain high solid content resin composition. The present invention
In the high solid content resin composition, the acrylic oligomer
-(A) and a curing agent having reactivity with the hydroxyl group (b)
And the weight ratio of the dissociation catalyst or the curing catalyst (c)
Preferably corresponds to the acrylic oligomer (a) 100
And the curing agent (b) having reactivity with a hydroxyl group is
92, 0.001 to 1 of the dissociation catalyst or the curing catalyst (c)
It is set within the range of 0.

[0008] The present invention also provides a high solid content resin composition of the present invention.
It is intended to provide a high solid content type coating material using a product as a binder .

Further, the present invention provides 1C-1B, 2C-1B,
2C-2B, 3C-2B and a method of applying a paint in an overcoat system, wherein the high solid content resin composition of the present invention or the high solid content type paint of the present invention is applied to an object to be coated. On the vertical surface of the object, before the sagging of the paint starts to occur, and until the paint no longer sags, by rotating the object about a substantially horizontal axis, substantially The present invention provides a coating method for performing coating without sagging.

The present invention also relates to 1C-1B, 2C-1B,
A method for baking a paint in 2C-2B, 3C-2B and an overcoat system, comprising applying a high solid content resin composition of the present invention or a high solid content type paint of the present invention to an object to be coated. When baking, on the vertical surface of the object to be coated, before sagging of the paint begins to occur, and
Until the paint does not cause sagging, the coating object is rotated about a substantially horizontal axis to perform substantially sagging coating , and then baking, which provides a paint baking method. is there.

In the present invention, the blocked hydroxyl group refers to a group having a structure represented by the following general formulas (I), (II) and (III).

[0012]

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(R ₁ and R ₂ in the formula each represent an alkyl group having 1 to 18 carbon atoms, a phenyl group or an aryl group, or a hydrogen atom, a chlorine atom or a fluorine atom. And R ₃ represents an alkyl group having 1 to 18 carbon atoms, a phenyl group or an aryl group.)

[0014]

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(R ₄ in the formula is a hydrogen atom or a group having 1 carbon atom.
Represents an alkyl group of 10 to 10, and R ₅ is at least selected from the group consisting of a cycloalkyl group, an aralkyl group, an aryl group, an alkoxyl group, an alkanoyloxy group, an alkyl group having 1 to 18 carbon atoms and a halogen atom. 1 to 22 carbon atoms substituted by one kind of atomic group
Represents an alkyl group. )

[0016]

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(Wherein X is at least one atom selected from the group consisting of an alkoxyl group, an aralkyl group, an aryl group, an aryloxy group, an alkanoyloxy group, an alkyl group having 1 to 10 carbon atoms and a halogen atom) Represents an alkyl group having 1 to 18 carbon atoms which may or may not be substituted with a group.)

Further, in the present invention, the expression that the hydroxyl group concentration after dissociation is 2.2 mol / 1,000 g or more means that
It defines the number of moles of hydroxyl groups present in 0 g of acrylic oligomer, and indicates that the oligomer has an abundance of 2.2 mol or more, that is, an existing concentration in a unit of 1,000 g of the oligomer. It is.

Examples of the above-mentioned monomers having the structure represented by the general formula (I) include trimethylsiloxyethyl (meth) acrylate and trimethylsiloxyethyl (meth) acrylate.
Including trimethylsiloxypropyl (meth) acrylate, trimethylsiloxybutyl (meth) acrylate, triethylsiloxyethyl (meth) acrylate or tributylsiloxypropyl (meth) acrylate, triphenylsiloxyalkyl (meth) acrylates or dimethyl-tert-butyl And siloxyalkyl (meth) acrylates.

That is, it is a form in which a hydrogen atom of a hydroxyl group in a hydroxyl group-containing polymerizable unsaturated monomer is blocked with a so-called silylating agent, but only in the above-mentioned monomers. It is not limited. That is, N-methylolated (meth) acrylamide or β-hydroxyethyl (meth) acrylate is reacted with ε-caprolactone, or various (meth) acrylates of polyoxyalkylene glycols are silylated. Strained ones can also be used.

As typical examples of the monomers having the structure represented by the general formula (II) above, 1-methoxy-ethoxyethyl (meth) acrylate, 1-ethoxy-ethoxyethyl ( (Meth) acrylate, 1-butoxy-ethoxyethyl (meth) acrylate, 1- (2-ethylhexanoxy) -ethoxyethyl (meth) acrylate, 1-isobutoxy-ethoxyethyl (meth) acrylate, 1-cyclohexyloxy-ethoxy Various 1-alkoxy-ethoxyethyl (meth) acrylates, such as ethyl (meth) acrylate.

That is, it is a form in which an alkyl vinyl ether is added to a hydrogen atom of a hydroxyl group in a hydroxyl group-containing polymerizable unsaturated monomer by addition reaction, but is limited to only the above-mentioned monomers. Not something. That is, N-methylolated (meth) acrylamide and β-hydroxyethyl (meth) acrylate are reacted with ε-caprolactone, or polyoxyalkylene glycols (meth) acrylates. Can also be used in the form of an addition reaction of the above vinyl ethers.

Examples of the monomers having the structure represented by the above-mentioned general formula (III), which are particularly typical, include those represented by the following chemical formula.

[0024]

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[0025]

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[0026]

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[0027]

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The number of carbon atoms of X in the general formula (III) is usually in the range of 1 to 18, preferably 2 to 6.

The amount of these various hydroxyl-blocked monomers is 0.5 mol / 1,000 g.
A range of 〜4 mol / 1,000 g is appropriate. 0.
When the amount is less than 5 mol / 1,000 g, the effect of lowering the viscosity is small. On the other hand, when it exceeds 4 mol / 1,000 g, the effect of the blocking agent on the volatile matter is smaller than the effect of decreasing the viscosity. Either case is not preferable because it causes an increase.

Further, polymerizable monomers having unblocked hydroxyl groups themselves can also be used. In particular, the use of monomers having good solubility is preferred. Illustrative examples of only such typical monomers include β-
A compound obtained by adding 1 to 6 mol of ε-caprolactone to hydroxyethyl (meth) acrylate, or (meth) acrylates of polyoxyalkylene glycol; hydroxyethyl acrylate, 3-hydroxypropyl (meth) acrylate; Various (meth) acrylates such as 4-hydroxybutyl (meth) acrylate and 2,3-dihydroxypropyl (meth) acrylate; various vinyl ethers such as hydroxyethyl vinyl ether and hydroxybutyl vinyl ether; allyl ether, hydroxyethyl Various allyl compounds such as aryl ethers; or monomers obtained by reacting glycidyl (meth) acrylate with oxycarboxylic acids; (meth) acrylic acid;
Monomers obtained by reacting a compound having one epoxy group; oligomers obtained by reacting fatty acids and hydroxy acids with epoxy group-containing oligomers; or oligomers containing carboxylic acid-containing oligomers Monomers obtained by reacting a compound having two epoxy groups.

The total amount of the monomers in which the hydroxyl groups are blocked and the hydroxyl group-containing monomers described above is 2.2 mol / 1,000 in terms of the concentration of the hydroxyl groups after dissociation.
g or more, preferably 2.8 mol / 1,000 g or more. When the amount is less than 2.2 mol / 1,000 g, a coating film having a sufficient cross-linking density cannot be obtained.
Not preferred.

As other monomers which can be copolymerized with the above-mentioned monomers, particularly typical ones are exemplified.
And various alkyl (meth) acrylates, which are esterified products of monohydric alcohols represented by ２２22 and (meth) acrylic acid, styrene, vinyltoluene, te
various alkyl esters such as rt-butylstyrene, glycidyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, (meth) acrylonitrile, cyclohexyl (meth) acrylate; (meth) acrylic acid or crotonic acid or Maleic acid,
Various unsaturated carboxylic acids such as fumaric acid or itaconic acid; maleic acid or fumaric acid and one carbon atom
Mono- or diesters with monohydric alcohols represented by the following formulas: (meth) acrylamide, (meth) dimethylacrylamide, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate; -Dialkylaminoalkyl (meth) acrylates; various phosphoric acid group-containing (meth) acrylates such as phosphonooxyethyl (meth) acrylate; α-olefins such as vinyl acetate, hexafluoropropylene and tetrafluoroethylene;
Or perfluoroalkyl / perfluorovinyl ethers such as trifluoromethyl trifluorovinyl ether and pentafluoroethyl trifluorovinyl ether; (per) fluorovinyl ethers; and perfluoroalkyl vinyl ethers (provided that the alkyl group has 1 to 18 carbon atoms). And the like). Of course, these vinyl monomers may be used alone or in combination of two or more depending on the desired coating film performance.

The acrylic oligomer obtained by copolymerizing the above-mentioned components has a number average molecular weight of 1,500.
The following is preferably in the range of 700 to 1,200. If it exceeds 1,500, the viscosity in a soluble or non-solvent state is extremely increased, and the amount of the diluting solvent is extremely increased, which is not preferable.

The polymerization of these monomers can be carried out by a known and commonly used method. Preferably, it can be easily carried out by a radical solution polymerization method. Methods for obtaining a low molecular weight polymer include a method using various chain transfer agents, including mercaptan compounds such as mercaptoethanol, thioglycerol, and lauryl mercaptan, and a method using a high temperature (usually within a range of 140 to 180 ° C). Alternatively, the desired acrylic oligomer having a blocked hydroxyl group can be easily obtained by a method of performing the reaction at a low monomer concentration.

Here, particularly typical solvents are exemplified as xylene, "Solvesso" (trade name;
Any solvent used in the production of ordinary acrylic polymers such as Exxon Co., Ltd.), butyl acetate, methyl ethyl ketone, methyl amyl ketone, butyl acetate, ethyl acetate and the like can be used. When a melamine resin is used as one kind of the hydroxyl-reactive curing agent (b), an alcohol-based solvent such as n-butanol, isobutanol, and butyl cellosolve can also be used.

The radical polymerization initiator can also be used if it is usually used. Among them, particularly typical ones are exemplified as benzoyl peroxide, lauroyl peroxide, tert-butyl hydroperoxide, tert-butylperoxy-2-ethylhexanoate, tert-amylperoxy-2-. Various peroxides such as ethylhexanoate and tert-amylperoxybenzoate; and various azo compounds such as azobisisobutyronitrile and azobis (2-methylpropionitrile). In addition, the method of so-called ionic polymerization such as anionic polymerization or cationic polymerization can be particularly advantageously used for copolymerization of monomers having a blocked hydroxyl group.

As the curing agent (b) (hydroxyl-reactive curing agent) having reactivity with a hydroxyl group used in the present invention, first, a polyisocyanate compound can be mentioned.
Xylene diisocyanate, isophorone diisocyanate, hydrogenated xylene diisocyanate, tolylene diisocyanate or hexamethylene diisocyanate, when only particularly representative ones are mentioned.
1,4-tetramethylene diisocyanate, 1,10-
Including various alkylene diisocyanate compounds such as decamethylene diisocyanate and 1,18-octadecamethylene diisocyanate, these various alkylene diisocyanate compounds, ethylene glycol,
Adducts with various polyhydric alcohols, such as glycerin or trimethylolpropane; or reactive with so-called active hydrogen, such as the reaction product of 1 mol of water with 3 mol of diisocyanates. The compound has a free isocyanate group and any known and commonly used compound can be used as long as it is in such a form. The most effective one as the polyisocyanate compound in the present invention is one having an isocyanurate ring, which is advantageous for hardness and low viscosity.

As the hydroxyl-reactive curing agent (b), 2
The second most important one is an alkylated melamine / formaldehyde resin, and those having a carbon number of 1 to 4 are usually used. That is, it is a so-called lower alcohol of C _{1 to} C ₄ , which is obtained partially or completely by etherification, and specifically, methyl etherified melamine, n-butyl ether Melamine or i
and so-butyletherified melamine. Among them, use of methyl etherified melamine is desirable from the viewpoint of high solid differentiation.

As the blocked polyisocyanate, a polyisocyanate obtained by blocking a so-called non-yellowing polyisocyanate with a known and commonly used blocking agent may be used.
-550 "(trade name; product of Dainippon Ink and Chemicals, Inc.)," Takenate B815-N "(trade name; product of Takeda Pharmaceutical Co., Ltd.) or" Azitol VKL-8 "
“0” (trade name; a product of Hoechst Gosei Co., Ltd.) is an example of a typical commercially available product.

Next, there can be mentioned an acid anhydride group-containing compound. As such a compound, an acid anhydride group-containing unsaturated monomer is copolymerized with a polymerizable monomer as described above. The resulting acid anhydride group-containing vinyl copolymers are particularly typical. Here, particularly typical examples of the acid anhydride group-containing unsaturated monomer include those represented by itaconic anhydride or maleic anhydride. In addition, particularly typical examples of the acid anhydride group-containing low molecular weight compound include trimellitic acid, tetrahydrophthalic anhydride, heptic anhydride, hymic anhydride, maleic anhydride, itaconic anhydride, and pyromellitic anhydride. Or glycerol tris (trimellitate).

In the present invention, the dissociation catalyst or curing catalyst (c), which is also referred to as the third component, refers to one which is hydrolyzed by a reaction with moisture in the air to regenerate a hydroxyl group. It goes without saying that a catalyst must be used to promote such hydrolysis,
Particularly representative examples of such catalysts include phosphoric acids, phosphoric esters, phosphites, unsaturated ester-containing phosphoric esters, p-toluenesulfonic acid and amine salts thereof; benzoic acid, trichloroacetic acid. And various acidic catalysts such as naphthalene disulfonate or amine salts thereof, or tetraethylammonium fluoride, and compounds that generate halogen ions such as chloride are effective.

The catalyst for accelerating the reaction between the generated hydroxyl group and the above-mentioned polyisocyanate compound as a curing agent is not particularly limited as long as it is usually used as a urethanization catalyst. It can be used without. Particularly typical examples of such urethanization catalysts include alkyl titanates, octylates, dibutyltin dilaurate, and lead octylates.
Metal salts of various carboxylic acids; various sulfide-type or mercaptide-type organic tin compounds such as monobutyltin sulfide and dioctyltin mercaptite. The amount of these is preferably in the range of 0.001 to 5% based on the acrylic oligomer,
A range of 0.005 to 2% is appropriate.

In the high solid content resin composition of the present invention,
The acrylic oligomer (a) reacts with the hydroxyl group.
Curing agent (b) having the above-mentioned dissociation catalyst or curing catalyst
The weight ratio with (c) is the acrylic oligomer (a) 10
The curing agent (b) having reactivity with a hydroxyl group is 5 to 0.
2-192, the dissociation catalyst or curing catalyst (c) is 0.00
1 to 10, more preferably 0.005 to 6 as appropriate
It is preferable to set. Further, if necessary, the high solid content resin composition or high solid content type coating material of the present invention (hereinafter, referred to as “high solid content type paint”)
Both of these may be represented as a resin composition, or conversely, as a paint. ), Known resins such as various resins and solvents, coloring agents such as various pigments and dyes, flow regulators, antioxidants, ultraviolet absorbers, light stabilizers or silane coupling agents. It is, of course, possible to add various conventional additives. In particular, as solvents, the use of so-called dipolar aprotic solvents having high water absorption is effective.

Next, using the resin composition of the present invention,
A coating method and a baking method of a paint (including a resin composition in some cases) in the C-1B, 2C-1B, 2C-2B, 3C-2B and overcoat system will be described. The resin composition of the present invention is used at the time of coating, in a state diluted with a minimum amount of solvents or in a state without solvent. And, when coating in any state, at the time of coating, the blocking agent dissociates in an atomized state, and when applied to the object to be coated, already regenerates the hydroxyl group and sharply It is to thicken. Therefore, it is less likely to sag as compared with the conventional one in which the viscosity is reduced only with solvents.

That is, in the case of a coating material containing a large amount of solvents as in the prior art, a sharp increase in viscosity accompanying the volatilization of such solvents causes a sharp increase in the coating process.
Although it is possible to prevent so-called primary sagging, as in the present invention, in the case of a solventless or low solvent content, high solid content resin composition or high solid content type paint, immediately after painting,
There is always the danger that sagging will occur on the surface of the coating object that extends vertically, that is, on the vertical surface, which will eventually cause poor coating film appearance (poor appearance).

In this regard, in the coating method of the present invention, the coating is performed while continuously rotating the object to be coated about a substantially horizontal axis, and the coating is performed at least until the coating no longer sags at least in the drying step. Since the rotation is maintained, primary sagging hardly occurs, and even if such primary sagging occurs, such primary sagging can be smoothed.

Therefore, in order to prevent so-called secondary sagging in the baking step, in order to prevent this, the operation of rotating around a substantially horizontal axis, which is a feature of the coating method or the baking method of the present invention, is performed from the painting step. It is absolutely necessary to continuously maintain it throughout the baking process.

The coating or baking method used in the present invention for rotating an object to be coated about a substantially horizontal axis is disclosed in
Although it is disclosed in US Pat. No. 1,658,871, the effect can be further expected by using the resin composition or the paint of the present invention. The rotation speed of the object is
Before gravity causes the composition of the present invention to sag, the rotational speed is changed from a vertical state to at least a horizontal state, and the centrifugal force resulting from the rotation causes sagging of the paint. The rotation speed is set to a range smaller than the rotation speed.

The conditions for the coating are as follows: the resin composition or the paint is heated, or the acrylic oligomer (a) and the hydroxyl-reactive curing agent (b) in the composition of the present invention,
The dissociation catalyst or the curing catalyst (c) may be blended immediately before use, or may be coated by various methods such as air atomization coating or airless coating.

The high solid content resin composition or high solid content type paint of the present invention is applied to the coating method and baking method of the present invention for so-called metal materials or metal products such as automobiles and building-related materials. Can be applied.

[0051]

EXAMPLES Next, the present invention will be described more specifically with reference examples, examples, application examples and comparative application examples. In the following, all parts and percentages are by weight unless otherwise specified. It is assumed that

Reference Example 1 (Preparation Example of Acrylic Oligomer Having Blocked Hydroxyl Group) 1,000 parts of xylene was placed in a four-necked flask equipped with a stirrer, an inert gas inlet, a thermometer, and a cooler. After charging and heating to 140 ° C., 250 parts of trimethylsiloxyethyl methacrylate, 80 parts of styrene, “Placel FM-1” (trade name; Daicel Chemical Industries, Ltd.)
Compound obtained by adding 1 mol of ε-caprolactone to 2-hydroxylethyl methacrylate manufactured by Toshiba Corporation
Parts and 50 parts of n-butyl acrylate, 500 parts of xylene, 30 parts of azobisisobutyronitrile and 50 parts of tert-butylperoxy-2-ethylhexanoate for 6 hours It dripped over.

Further, the reaction was carried out at the same temperature for 5 hours,
After obtaining a resin solution having a nonvolatile content of 25%, xylene was distilled off under reduced pressure. 25 of the resin obtained here
The viscosity at 1 ° C. was 1,800 centipoise, and the molecular weight was 980. (Hereinafter abbreviated as OHB-1)

Reference Example 2 (Preparation Example of Acrylic Oligomer Having Blocked Hydroxyl Group) In the same apparatus as in Reference Example 1, 1,0
Of styrene as a monomer mixture.
0 parts, 300 of trimethylsiloxybutyl acrylate
A resin solution was obtained in the same manner as in Reference Example 1, except that 100 parts of "Placcel FM-1" and 50 parts of n-butyl methacrylate were used.

The resin solution obtained here had a nonvolatile content of 2
7.8%, and the viscosity of the resin from which the solvent was distilled off was 1,90.
It was 0 centipoise and the molecular weight was 880. (Hereinafter abbreviated as OHB-2)

Reference Example 3 (Preparation Example of Acrylic Oligomer Having Blocked Hydroxyl Group) In the same apparatus as in Reference Example 1, dehydrated 1-methoxy-
To a mixture consisting of 350 parts of ethoxyethyl methacrylate, 100 parts of n-butyl methacrylate and 50 parts of 2-ethylhexyl methacrylate, 100 parts of a sec-butyl-Li / benzene (20/80) solution was added. After stirring for 2 hours, 20 parts of hydrochloric acid-methanol was added, the solvent was removed, and the mixture was filtered to obtain a resin solution having a molecular weight of 1,000 and a viscosity of 1,800 centipoise. (Hereinafter, OHB-3
Abbreviated. )

Reference Example 4 (Preparation Example of Acrylic Oligomer Having Blocked Hydroxyl Group) In the same apparatus as in Reference Example 3, 250 parts of demethylated trimethylsiloxyethyl methacrylate and 250 parts of n-butyl methacrylate were used. A monomer mixture consisting of
200 of tetrahydrofuran previously dehydrated
And 10 parts of a green complex (Na-naphthalene) obtained by reacting naphthalene 1: 1 with sodium metal in tetrahydrofuran, and stirring for 2 hours. To obtain a polymer having a molecular weight of 1,500, and then add 20 parts of methanol,
After sufficiently stirring, the solvent was distilled off and the viscosity was 2,
A solventless resin of 000 cps was obtained. (Hereinafter OH
Abbreviated as B-4. )

[Reference Example 5] (Preparation Example of Acrylic Oligomer Having Blocked Hydroxyl Group) In a 3-liter autoclave, 1,0 of xylene was added.
100 g and set it so that there is no leakage.
After heating to ℃, a mixture consisting of 100 parts of styrene, 300 parts of n-butyl methacrylate, 600 parts of trimethylsiloxyethyl methacrylate and 100 parts of di-tert-butyl peroxide was injected over 5 hours, Further, after the reaction was performed for 4 hours, xylene was distilled off, and the viscosity under a solvent-free condition was 2,2.
An acrylic oligomer having 200 centipoise and a molecular weight of 1,100 was obtained. (Hereinafter, abbreviated as OHB-5.)

Reference Example 6 (Preparation Example of Acrylic Oligomer Having Hydroxyl Group) 500 parts of xylene and 300 parts of n-butanol were charged, and 100 parts of styrene as a monomer mixture were charged.
Parts, 60 parts of butyl acrylate, 195 parts of β-hydroxyethyl methacrylate and “Placcel FM
The reaction was carried out in the same manner as in Reference Example 1, except that a mixture consisting of 145 parts of -1 "and 75 parts of tert-butyl per-2-ethylhexanoate were used.
A control resin having a viscosity of 40 poise after desolvation and a number average molecular weight of 1,120 was obtained. (Hereinafter abbreviated as OH-1)

Reference Example 7 (Preparation Example of Acrylic Oligomer Having Hydroxyl Group) A 10% aqueous solution of phosphoric acid was added to the acrylic resin containing a hydroxyl group obtained in Reference Example 4, and the mixture was sufficiently stirred. As a result, a control acrylic resin having a resin viscosity of 40 poise and a molecular weight of 1,200 was obtained.
(Hereinafter abbreviated as OH-2)

Examples 1 to 6 Using the respective resins obtained in Reference Examples 1 to 5, the resin composition of the present invention was prepared by a conventional method in accordance with the compounding composition ratios shown in Table 1 below. Was prepared.

Comparative Examples 1 and 2 Reference Examples 6 and 7
Using the respective resins obtained in the above, a resin composition for control was prepared by a conventional method according to the composition ratio shown in Table 1 below.

[Application Examples 1 to 6 and Comparative Application Example 1]
And 2] xylene / n-butyl acetate (weight ratio = 6) such that each of the resin compositions obtained in Examples 1 to 6 and Comparative Examples 1 and 2 has a centrifugal pressure of 150 centipoise.
0/40) by adjusting the viscosity with a mixed solvent of
The coating non-volatile content of each composition was measured. The results are collectively shown in Table 2 below.

Next, as described above, coating was performed using these diluted compositions while rotating the object to be coated at a rotation speed of 10 rpm. Then, while rotating, let stand for 10 minutes.
Drying and baking were performed for 0 minutes, and during baking, rotation was performed at the same speed for 10 minutes after being placed in the drying oven. On the other hand, using the same diluted composition, the object to be coated was simply applied to a stationary vertical surface without rotating at all. And after 10 minutes of natural drying, 140
Baking was performed in a dryer in a vertical state under a condition of ° C./20 minutes.

At this time, the situation of occurrence of wrinkles and the state of sagging of the coating film are comprehensively observed to determine whether the method is legal. The results are collectively shown in Table 2 below. The cured coating film was further subjected to a comparative study of various performances. The results are shown in Table 2 below.

[0066]

[Table 1]

[0067]

[Table 2]

<< Footnotes in Table 1 >>"DN-901S" means "Barnock DN-901
S ", which is a polyisocyanate resin manufactured by Dainippon Ink and Chemicals, Inc. “BO-357” is an abbreviation for “Barnock BO-357” and is a block isocyanate resin manufactured by the same company. "HMMM" is an abbreviation for hexamethoxymethylmelamine compound. As the “dissociation catalyst (C-1)”, a monoisopropyl ester of phosphoric acid was used. As the “dissociation catalyst (C-2)”, trifluoromethanesulfonic acid was used. As the "curing catalyst (C-3)", di-n-butyltin dilaurate was used. The numerical values represent the solid content weight.

[0069]

[Table 3]

[0070]

[Table 4]

<< Footnote to Table 2 >> Limit film thickness 1 ... Limit film thickness at which no splash occurs when coating is performed while rotating. 〃2 .............. Limited film thickness that does not cause wrinkles when applied to a stationary vertical surface. Sagging limit film thickness 1 ... Limit film thickness that does not cause sagging when painting while rotating. 〃2 ......... Limited film thickness that does not cause sagging when applied to a stationary vertical surface. Storage stability: Performed on the stability immediately after the preparation of the resin composition (paint) (that is, the initial stability) and the stability after holding at 50 ° C. for 2 days. Are the "seconds" of Ford Cup # 4
Is represented. Gloss: Displayed with 60-degree specular reflectance (%). Impact resistance: Performed with a 1 / 2-inch notch and indicated at 500 g / cm. Xylene rubbing: The surface state of the coating film at the time when the number of rubbings was 10 was visually determined. Acid resistance: At 60 ° C., 0.5 milliliter (ml) of a 5% sulfuric acid aqueous solution was dropped, and the state of the coated surface was visually determined. Alkali resistance ···· At room temperature, after immersion in a 5% sodium hydroxide aqueous solution for 24 hours, the state of the coated surface is visually judged. Weather resistance: Using a QUV panel 2,
Gloss retention (%) after accelerated weathering test over 000 hours
Displayed with.

[0072]

As described in detail above, the thermosetting resin composition of the present invention comprises, as an active ingredient, a low molecular weight acrylic resin containing a hydroxyl group-blocked functional group as an essential component, a curing agent having, comprising a dissociation catalyst (dissociation promoters) or curing catalyst (curing accelerator)
Xylene / n-butyl acetate (weight ratio = 60/4
0) when diluted to 150 cps with mixed solvent
Is a high solid content resin composition having a non-volatile content of 74.5% or more.
is there.

The high solid content resin composition of the present invention and the high solid content type coating material of the present invention having such a constitution are extremely excellent in solubility in an organic solvent. Moreover, due to the generation of hydroxyl groups at the time of coating, drastic increase in viscosity makes it difficult to cause sagging at the time of painting or baking. It has the advantage of being extremely unlikely.

Further, according to the present invention, when coating or baking using a high solid content resin composition having such a structure and a high solid content type paint, the object to be coated is applied at an appropriate speed. It is intended to provide a coating method and a baking method of rotating. Therefore, it is extremely effective in improving the smoothness of the coating film.

The baked coating film thus obtained is extremely excellent in solvent resistance, weather resistance, scratch resistance and the like, which is useful as a top coat for automobiles.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI C08G 18/42 C08G 18/42 18/62 18/62 C09D 133/00 C09D 133/00 175/04 175/04 (72) Invention Person Yoshiaki Marutani 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Inventor Hiroyuki Uemura 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Shinji Sasaki, inventor Shinji Sasaki, Hiroshima 3-1 Fuchu-cho Shinchi Mazda Co., Ltd. (72) Inventor Kazuyo Koga 3-1 Fuchu-cho Shinchi, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (56) References JP-A-64-36641 (JP, A) 3-165871 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 33/00 B05D 1/36-1/40 B05D 3/02 B05D 7/24 C08G 18/42 C08G 18 / 62 C09D 133/00 C09D 175/04 WPI (DIALOG)

Claims (6)

(57) [Claims] An acrylic oligomer (a) having a blocked hydroxyl group, having a number average molecular weight of 1,500 or less, and having a hydroxyl group concentration of 2.2 mol / 1,000 g or more after dissociation, and a hydroxyl group A curing agent (b) reactive with
A dissociation catalyst or a curing catalyst (c) is contained as an essential film-forming component , and xylene / n-butyl acetate
(Mixture ratio = 60/40) with a viscosity of 150 cps
A high solid content resin composition having a non-volatile content of 74.5% or more when diluted with a . 2. It has a blocked hydroxyl group as described above,
Acrylic oligomer (a) having a number average molecular weight of 1,500 or less and a hydroxyl group concentration of 2.2 mol / 1,000 g or more after dissociation is at least the following general formula (I):
2. The composition according to claim 1, wherein the concentration of the blocked hydroxyl group is 50% or more with respect to the concentration of the unblocked hydroxyl group, having any one of the structures represented by (III). 3. High solid content resin composition. Embedded image (R ₁ and R ₂ in the formula each have 1 to 1 carbon atoms.
8 represents an alkyl group, a phenyl group or an aryl group, or a hydrogen atom, a chlorine atom or a fluorine atom, which may be the same or different, and R ₃ represents an alkyl group having 1 to 18 carbon atoms, a phenyl group Or an aryl group. ) (In the formula, R ₄ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ₅ represents a cycloalkyl group, an aralkyl group, an aryl group, an alkoxyl group, an alkanoyloxy group, and a carbon atom having 1 to 18 carbon atoms. Represents an alkyl group having 1 to 22 carbon atoms and substituted with at least one atomic group selected from the group consisting of an alkyl group and a halogen atom. (X in the formula is substituted with at least one atomic group selected from the group consisting of an alkoxyl group, an aralkyl group, an aryl group, an aryloxy group, an alkanoyloxy group, an alkyl group having 1 to 10 carbon atoms and a halogen atom. May be substituted or unsubstituted, and has 1 to 18 carbon atoms.
Represents an alkyl group. ) 3. The acrylic oligomer (a),
A curing agent (b) reactive with hydroxyl groups, and the dissociation catalyst
Or, if the weight ratio with the curing catalyst (c) is
With respect to mer (a) 100, a hard resin having reactivity with a hydroxyl group
Agent (b) is 52 to 192, a dissociation catalyst or a curing catalyst;
(C) is 0.001 to 10
Item 7. The high solid content resin composition according to Item 1. 4. A high solid content type paint comprising the high solid content resin composition according to claim 1 as a binder. 5. One coat and one bake, two coats and one bake,
A method for coating a paint in a two-coat two-bake, three-coat two-bake, and overcoat system, wherein the high solid content resin composition according to claim 1 or the high solid content according to claim 4 is used. When applying the coating composition to an object to be coated, on the vertical surface of the object to be coated, before the sagging of the paint starts to occur, and until the paint no longer sags, the object to be coated is A method of coating a paint, characterized by rotating about a substantially horizontal axis. 6. One coat and one bake, two coats and one bake,
A method for baking a paint in a two-coat two-bake, three-coat two-bake, and overcoat system, wherein the high solid content resin composition according to any one of claims 1 to 3 or the high solid content according to claim 4 is used. When applying the separating paint to the object to be coated and then baking, on the vertical surface of the object to be coated before the start of sagging of the paint and until the paint no longer sags. The coating is performed by rotating the object to be coated about a substantially horizontal axis,
A method for baking paint, comprising baking.