JPH0659452B2 - Paint finish method - Google Patents

Description

The present invention relates to a so-called two-coat, one-bake coating finishing method in which two different kinds of coating materials are overcoated and then cured, and more specifically, a group having room-temperature dissociation property is dissociated. Then, a resin composition containing a vinyl polymer that forms a hydroxyl group and a curing agent as main components, and a resin that contains a vinyl polymer that forms a carboxyl group after the group having room-temperature dissociation dissociates and a curing agent as the main components The present invention relates to a two-coat, one-bake paint finishing method in which the composition is used in combination as a paint for a base coat and a paint for a top coat.

In recent years, in the coating finish method for automobile top coating, not only the metallic coating finish method of coating a coating material containing metallic powder, but also the so-called solid color coating finishing method of coating a coating material containing a coloring pigment After painting the clear paint
It has been recognized that a two-coat, one-bake coating finishing method for coating (including a colored coating that does not impair the transparency) is effective.

That is, the coating film obtained by this 2 coat, 1 bake coating finish has an excellent finished appearance and feeling of flesh, and 1 coat,
The 1-bake metallic finish method has a remarkable drawback in chemical resistance, but the 2-coat, 1-bake finish method improves the drawback. Conventional solid color paints containing vinyl polymer as a main component also have a remarkable defect in weather resistance. By using this 2 coat, 1 bake coating finishing method, a coating film excellent in weather resistance can be obtained. The 2-coat, 1-bake coating finishing method has various advantages.

Generally, the two-coat, one-bake paint finishing method is to coat the base coat paint with an aminoalkyd resin paint, a thermosetting acrylic resin paint, etc., coat the base coat, and leave it for 2 to 5 minutes to evaporate some solvent. After
Immediately apply the same type of top coat paint, and then in a hot-air drying oven at an temperature of 140-150 ° C for 20-30
It is baked and cured for a minute. Here, heavy oil, propane gas, butane gas, city gas or electric power is used as a source of hot air, but 2 coats using a conventional thermosetting coating material that is heat-cured at 140 to 150 ° C.
The bake coating finishing method has a drawback in that the cost is increased due to fuel consumption and electric power consumption.

On the other hand, in the automobile industry, plasticization of outer panels and parts is rapidly progressing. When the material is a steel plate, so-called baked one-pack type paints such as the above-mentioned aminoalkyd resin paints and thermosetting acrylic resin paints are usually adopted as the paint resin system used. However, when the material is made into plastic, the heat resistant temperature of the material is low in some cases, and it is inappropriate to use a normal baking one-pack type paint for plastic. Therefore, room temperature curing type and low temperature curing type coatings have been studied or partially used for plastics. Examples of these paint resins include a combination of a polyol type resin and an isocyanate prepolymer, a combination of an acrylic resin having a tertiary amino group and a polyfunctional epoxy resin, and a curing system by aminoplast using a low temperature curing catalyst. However, among such paint systems, the polyol resin-isocyanate prepolymer system and the tertiary amino-epoxy resin curing system are both two-pack type and have a major drawback in terms of workability such as pot life.

In addition, although the aminoplast system using a low temperature curing catalyst is a one-pack type as a form, it has a drawback that the functional groups involved in the reaction are not blocked and are highly active, and the storage stability over a long period is extremely poor. However, it is impossible to cure at a temperature near room temperature.

In addition, if an isocyanate obtained by blocking the isocyanate prepolymer with a suitable blocking agent is used, a one-pack type polyol resin-isocyanate prepolymer curing system is used, but at present, the dissociation temperature of the blocking agent is high, at room temperature or low temperature. It is hard to say that it is a curable resin system.

As described above, in the coating finish method for automobile top coating, from the viewpoint of energy saving and material conversion, a one-part type room temperature or low temperature curable resin having excellent coating workability, various physical properties, weather resistance and storage stability is used. The reality is that there is a demand for rapid development of the two-coat, one-bake coating.

The inventors of the present invention have applied the two coats, 1
As a result of diligent study to obtain a paint for bake painting finish,
For combination of base coat paint and top coat paint,
As a resin composition for paints, [I] 1 to 100% by weight of a vinyl-based monomer (A) having a polymerizable unsaturated group and at least one siloxy group in one molecule and a copolymer other than (A) are copolymerizable A resin composition comprising a vinyl polymer comprising 99 to 0% by weight of a vinyl monomer (B), a curing agent and a dissociation accelerating catalyst, and [II] at least a polymerizable unsaturated group in a molecule. 1 to 1 of vinyl-based monomer (C) having one carboxysilane group
A resin composition comprising a vinyl polymer comprising 100% by weight and 0 to 99% by weight of a copolymerizable vinyl monomer (D) other than (C), a curing agent and a dissociation promoting catalyst.
It has been found that a coating finishing method using a combination of different kinds of selected compositions satisfies the above-mentioned requirements, and has completed the present invention.

That is, according to the present invention, the siloxy group in the vinyl-based polymer reacts with moisture in the air to form a hydroxyl group in the vinyl-based polymer, and the hydroxyl group is reacted with a cross-linking agent component having reactivity to form a strong coating. A crosslinker component that forms a film, and causes the carboxysilane group in the vinyl polymer to react with moisture in the air to form a carboxyl group in the vinyl polymer, and which has reactivity with the carboxyl group. And a resin composition [I] and [II] (but not the same as [I]) containing the vinyl polymer and the vinyl polymer as main components, respectively, are used as paints. By using in combination (one is used as the base paint and the other is used as the top paint), it is a one-pack type that has excellent storage stability and can be cured at room temperature or low temperature. How to finish painting It is intended to provide.

Here, the vinyl-based monomer (A) constituting the vinyl-based polymer contains a polymerizable unsaturated group and at least one siloxy group bonded to a carbon atom represented by the following formula in one molecule. It is a vinyl-based monomer.

(However, R ₁ , R ₂ and R ₃ represent an alkyl group consisting of C _{1 to} C ₁₈ , a phenyl group, an aryl group or H, and may be the same or different.) These vinyl monomers (A) are, for example, Obtained by reacting trialkylchlorosilane or triphenylchlorosilane, triarylchlorosilane, dialkylchlorosilane, etc. with a hydroxyl group-containing vinyl monomer (b) as described below in the presence of a hydrochloric acid scavenger such as triethylamine or pyridine. Trimethylsiloxyethyl (meth) acrylate, trimethylsiloxypropyl (meth) acrylate, trimethylsiloxybutyl (meth) acrylate, representative of them.
Examples thereof include triethylsiloxyethyl (meth) acrylate, tributylsiloxypropyl (meth) acrylate and triphenylsiloxyalkyl (meth) acrylate. These can be used alone or as a mixture of two or more kinds.

Further, as the hydroxyl group-containing vinyl monomer (b),
Hydroxyalkyl such as β-hydroxyethyl (meth) acrylate, β-hydroxypropyl (meth) acrylate or β-hydroxybutyl (meth) acrylate
(Meth) acrylates or N-methylolated (meth) acrylamide; β-hydroxyethyl (meth) acrylate to which ε-caprolactone is added [eg Praxel FM, FA series (manufactured by Daicel Chemical Industries, Ltd.) and TONE] ^TM M-100 (manufactured by Union Carbide Co., Ltd.)]; Blemmer PP-1000 represented by a general name of polypropyken glycol monomethacrylate and Blemmer PE series represented by a general name of polyethylene glycol monomethacrylate (both manufactured by NOF Corporation); Unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, fumaric acid or itaconic acid, and "Cajyura E" (Shell Chemical Co., Ltd.)
Made, glycidyl ester of branched fatty acid), monoglycidyl ester of monovalent carboxylic acid such as octyl acid glycidyl ester or coconut oil fatty acid glycidyl ester or monoglycidyl ethers such as butyl glycidyl ether. And the additions; and the like are typical. The amount of the vinyl-based monomer (A) used is preferably 1 to 100% by weight, and more preferably 5 to 90% by weight. If it is less than 1% by weight, the effect of the monomer cannot be expected.

Typical examples of the vinyl-based monomer (B) include an alkyl (meth) acrylate having an alkyl group having 1 to 22 carbon atoms in the side chain, styrene, vinyltoluene, t-
Butyl styrene, α-methyl styrene, glycidyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, (meth) acrylonitrile, cyclohexyl (meth) acrylate, maleic acid or fumaric acid and C ₁ -C ₁₈
And diesters with monohydric alcohols, (meth) acrylamides such as (meth) acrylamide or N-alkoxymethylated (meth) acrylamide, N, N dialkylaminoalkyl (meth) acrylates, or phosphoric acid group-containing (meth) ) Acrylates, vinyl fluoride-containing monomers such as vinyl acetate, hexafluoropropylene and tetrafluoroethylene.

These vinyl-based monomers (B) can be used alone or as a mixture of two or more types depending on the desired coating film performance. It is also possible to use the above hydroxyl group-containing vinyl-based monomer (b) as the vinyl-based monomer (B) component.
However, if the functional group is not blocked and an isocyanate prepolymer is used as a curing agent, the storage stability as a one-pack type coating is poor, and the hydroxyl group-containing vinyl monomer (b)
Is not preferred. On the other hand, when aminoplast is used as a curing agent, hydroxyl group-containing vinyl monomer
It is possible to use (b). However, if necessary, consider adding a curing catalyst to impart low temperature curability,
The amount used should be less than 5% by weight, which does not adversely affect the storage stability as a one-pack type.

In order to obtain the vinyl polymer (I) constituting the composition of the present invention, a known conventional method using the above-mentioned monomers, for example, a solution polymerization method using a radical generator is used. Can be done.

As the radical generator, any of those usually used for the polymerization of vinyl-based monomers may be used, but among them, representative ones include azobisisobutyronitrile and di-tert-butyl. Examples of the solvent include peroxide and benzoyl peroxide.
Solvents such as aromatic hydrocarbons such as toluene or xylene; acetic ester such as ethyl acetate, butyl acetate or cellosolve acetate; ketone such as methyl ethyl ketone or methyl isobutyl ketone can be used.

Further, if necessary, a commonly used chain transfer agent such as mercaptans, α-methylstyrene and “dipentene T” (manufactured by Nippon Terpene Chemical Co., Ltd.) can be used.

The vinyl polymer (I) thus obtained has a number average molecular weight.
The range in which (n) is 500 to 50,000 is preferable.

When n of the copolymer (I) is less than 500,
The physical properties of the coating film cannot be sufficient, and the hydroxyl value generated after the trialkylsiloxy groups and the like of the polymer (I) are liberated to obtain the physical properties of the coating film (hereinafter, referred to as "OH
Value ". ) Is not preferable because the coating film becomes brittle, and on the contrary, when it exceeds 50,000, the appearance of the coating film,
It is not preferable because defects are likely to appear in gloss, feeling of flesh, workability in painting, and the like.

Next, as the cross-linking agent (II) which is another component constituting the composition of the present invention, when only the hydroxyl group generated from the vinyl-based monomer (A) is a functional group, the cross-linking agent (II )
As such, polyisocyanates and aminoplasts are used.

Typical polyisocyanates include aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate or xylylene diisocyanate; aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate or trimethylhexane diisocyanate; isophorone diisocyanate, methylcyclohexane. -
2,4- (or 2,6-) diisocyanate, 4,4 '
Alicyclic diisocyanates such as methylenebis (cyclohexylisocyanate or 1,3-di (isocyanatomethyl) -cyclohexane, and each of these diisocyanates and polyhydric such as ethylene glycol, propylene glycol, neopentyl glycol or trimethylolpropane Alcohols; polyester resins having a functional group capable of reacting with an isocyanate group and having an extremely low molecular weight (including oil-modified types); or adducts with water, etc., in the form of biuretite, or the above-mentioned diisocyanates having a heavy weight. It is a combination (including an oligomer), and the compounding ratio of these polyisocyanates and the vinyl polymer (I) is OH groups / NO produced.
A range of C group = 1 / 0.5 to 1/3 (equivalent ratio) is preferable from the viewpoint of coating film performance. In this case, either a one-pack type in which polyisocyanates are mixed in advance or a two-pack type in which polyisocyanates are mixed immediately before coating can be used.

On the other hand, when a specific amount of the hydroxyl group-containing vinyl monomer (b) is used in the vinyl polymer, aminoplast is preferable as the crosslinking agent in consideration of storage stability.

However, it is also possible to mix and use polyisocyanates immediately before coating. A typical aminoplast which is etherified with a monohydric alcohol is usually used. However, the presence of alcohol in the coating composition of the present invention may cause a reaction with siloxy groups to cause a drawback in long-term stability. Therefore, hexamethoxymethylolmelamine, which does not use alcohol as a resin solvent, is preferable as the aminoplast.

The amount of aminoplast used is preferably 10 to 40% by weight of the vinyl polymer. Further, a curing accelerator for aminoplast, for example, an acid catalyst such as paratoluenesulphonic acid may be added to increase the crosslinkability.
The amount of the curing accelerator used is 0.1 with respect to the resin solid content.
-10 wt% is preferable. When long-term storage stability is not required, aminoplast etherified with a monohydric alcohol containing alcohol may be used as the resin solvent.

When exposed to the atmosphere, the composition of the present invention is hydrolyzed by a reaction with moisture in the air to generate a hydroxyl group capable of reacting with a curing agent. A catalyst must be used to accelerate this hydrolysis. As catalyst, phosphoric acid, phosphoric acid ester,
Acid catalysts such as phosphite, p-toluene, sulfonic acid and its amine salt, benzoic acid, trichloroacetic acid, trifluoroacetic acid, naphthalenedisulfonic acid and amine salt, ethylenediamine, N-β-aminoethyl-γ- Aminopropyltrimethoxysilane, butylamine, dibutylamine, t-butylamine, hexylamine, triethylamine, and other amines, potassium hydroxide, lithium hydroxide, sodium hydroxide, and other alkali catalysts, alkyl titanates, octylates, dibutyl Metal salts of carboxylic acids such as tin dilaurate and lead octylate, monobutyltin sulphide, sulphide type such as dioctyltin mercaptite, mercaptide type organotin compounds, tetraethylammonium fluorite, compounds producing fussoion such as cesium fluoride are effective. A. The amount of these curing catalysts added is 0.001 to 10% by weight, preferably 0.005 to 8% by weight, based on the vinyl polymer.

Further, since the composition of the present invention does not form a hydroxyl group capable of reacting with the curing agent unless it is exposed to the atmosphere, the composition of the present invention is a one-pack type composition having good stability. However, in order to ensure long-term storage stability, it is only necessary to capture a small amount of water that enters for some reason. That is, long-term stability is ensured by adding a water-binding agent having reactivity with water. Further, this water-binding agent may be used by mixing it in the initial stage when the vinyl polymer is produced. Examples of the water-binding agent having reactivity with water include trialkyl orthoformates such as trimethyl orthoformate, triethyl orthoformate, and tributyl orthoformate; trialkyl orthoacetates such as trimethyl orthoacetate, triethyl orthoacetate, and tributyl orthoacetate. Trialkyl orthoborates such as tributyl orthoborate and triethyl orthoborate; Tetra (substituted) such as tetramethylsilicate, tetraethylsilicate, tetrabutylsilicate, tetra (2-methoxyethyl) silicate or tetra (2-chloroethyl) silicate Alkyl silicates alone; Tetraphenyl silicates, equivalent substances of the above tetra (substituted) alkyl silicates such as tetrabenzyl silicates (hereinafter abbreviated as synonymous simple substance); or tetraethyl silicate dimer Trimer, tetramer, hexamer "Ethyl silicate 40" (Colcoat Co., Ltd. product, tetramer of tetraethyl silicate, pentamer, mixture of hexamers), etc. Each of the above listed tetra (substituted) alkyl silicates alone or the same effect of the silicates Hydrolyzable ester compounds such as condensates of simple substances, phenyl isocyanate, p-chlorophenyl isocyanate, benzenesulphonyl isocyanate, p-trienesulphonyl isocyanate, isocyanate ethyl methacrylate (NCO of Dow Chemical Co.) Compounds having an isocyanate group such as a group-containing monomer).

The amount used is 0.1 to 3 with respect to the vinyl polymer.
0 wt%, preferably 0.5 to 20 wt% is good.

Then the general formula (Provided that R ₁ , R ₂ and R ₃ represent an alkyl group, a phenyl group, an aryl group or H represented by C _{1 to} C ₁₈ and may be the same or different, respectively). Is a vinyl monomer containing a carboxyl group in the presence of a hydrochloric acid scavenger such as triethylamine or pyridine, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid or fumaric acid; maleic acid monoalkyl ester, fumaric acid. A monoalkyl ester or a monoalkyl itaconic acid ester; or a carboxyl group-containing vinyl monomer such as an adduct of a vinyl monomer having a hydroxyl group with an acid anhydride such as succinic anhydride or trimellitic anhydride, and triethyl Trialkylchlorosilanes such as chlorosilanes and dials such as diethylchlorosilanes General formulas such as chlorchlorosilane, triphenylchlorosilane and triarylchlorosilane (However, R ₁ , R ₂ and R ₃ represent H, an alkyl group, a phenyl group and an aryl group, and may be the same or different.) A vinyl monomer obtained by reacting with a silane compound represented by To do. Then, as the other monomer (D) having a copolymerizability with the vinyl-based monomer, the above-mentioned vinyl-based monomer (B) other than the hydroxyl group-containing vinyl-based monomer may be used as it is. The vinyl monomer (C) is used in an amount of 1 to 10
It is 0% by weight, preferably 5 to 90% by weight, and if less than 1% by weight, desired physical properties cannot be obtained.

In order to prepare a vinyl polymer using the vinyl monomers (C) and (D) described above, the above-mentioned method for preparing a vinyl polymer may be used as it is. The molecular weight is preferably in the range of 500 to 50,000.

When the number average molecular weight is less than 500, desired performance cannot be obtained, while when it exceeds 50,000, workability is adversely affected.

Next, a polyvalent metal alkoxide or a chelate compound is used as a curing agent having reactivity with a carboxyl group generated from a polymer.

Examples of these compounds include aluminum, titanium, zirconium, kozilto, zinc, copper, lead, magnesium,
Typical examples are vanadium, iron or nickel alkoxides or chelate compounds, but curability,
Among these, aluminum, titanium, and zirconium alkoxides or xylate compounds are particularly preferable from the viewpoints of low toxicity and low colorability.

Specific examples of the alcoholate of such a metal include aluminum isopropylate, aluminum-n-butyrate,
Aluminum-sec-butyrate, aluminum isobutyrate, aluminum, -t-butyrate, tetra-n-propyl titanate, tetra-i-propyl titanate, tetra-n-butyl titanate, tetra-n-butyl titanate dimer, tetra-n -Butyl titanate tetramer, tetra-sec-butyl titanate, tetramethyl zirconate, tetraethyl zirconate, tetra-i-propyl zirconate, tetra-n-butyl zirconate, tetra-i-
Butyl zirconate and the like can be mentioned.

On the other hand, a polyvalent metal chelate compound can be prepared by reacting the alcoholate with a chelating agent, and specific examples of the chelating agent include monoethanolamine, diethanolamine, triethanolamine and dimethylaminoethanol. Alkanol amines such as, aceto chain esters such as methyl acetoacetate and ethyl acetoacetate, β-diketones such as acetylacetone and benzoylacetone, malonic acid esters such as dimethyl malonate and diethyl malonate, methyl salicylate, salicylic acid Salicylates such as ethyl, ethylene glycol, 1,3-propanediol,
Examples thereof include glycols such as 1,3-butanediol and octylene glycol, oxyacids such as lactic acid and tartaric acid or esters thereof, and further diacetone alcohol and catechol.

And specific examples of the complex compound obtained from the alcoholate and the chelating agent, aluminum bis (ethyl acetoacetate) monoisopropylate, aluminum tris (ethyl acetoacetate), aluminum bis (ethyl acetoacetate) monoacetoacetonate, Di-i-propoxy-bis (acetylacetone) titanate, di-i-propoxy-bis (ethylacetoacetate) titanate, di-n-butoxy-bis (acetylacetone) titanate, di-n-butoxy-bis (triethanolamine) Titanate, tetraoctylene glycol titanate, n-
Butoxy-tris (acetylacetone) zirconate, n-
Butoxy-tris (ethylacetoacetate) zirconate, tetrakis (acetylacetone) zirconate, tetrakis (ethylacetoacetate) zirconate, tris
Examples thereof include (acetylacetone) monoethylacetoacetate zirconate and bis (acetylacetone) bis (ethylacetoacetate) zirconate.

And, the compounding amount of the above-mentioned curing agent with respect to the vinyl-based polymer is set so as to fall within the range of 0.01 to 10% by weight, preferably 0.05 to 5% by weight with respect to the vinyl-based polymer. Is preferred. If the amount used is less than 0.01% by weight, the curability will be poor, and if it exceeds 10% by weight, the cured product will be extremely brittle, which is not preferable.

Further, as the catalyst for accelerating the dissociation of the bond between the carboxyl group and the silane compound in the vinyl-based polymer, the dissociation-accelerating catalyst used in the vinyl-based polymer may be used as it is. 0.001-
It is recommended to use 10% by weight, preferably 0.005 to 8% by weight.

Further, when the above water binder is used in the vinyl polymer in the same ratio as that used in the vinyl polymer, the stability of the coating is improved.

The resin compositions [I] and [II] thus obtained have 2 coats,
It is used as a top coat paint and a base coat paint in the 1-bake paint finishing method. When used as a top coat paint, it can be used as it is as a clear paint, but if necessary, a coloring pigment or dye can also be used. On the other hand, when used as a coating material for a base coat, known and commonly used aluminum powder, copper powder,
Metallic powders such as mica powder, inorganic pigments such as titanium oxide and calcium carbonate, and organic pigments such as phthalocyanine blue, toluidine red, and benzidine yellow are mixed, and metallic paints or solid color paints are prepared by a known conventional coating method. It may be prepared.

In addition, various conventional additives such as a leveling agent, an ultraviolet absorber and a pigment dispersant may be used in the top coat paint and the base coat paint, if necessary.

Air spray coating and electrostatic spray coating are suitable for coating top coat paints and base coat paints using the compositions [I] and [II], and the dry film thickness of the top coat paint is 10 -100 μm, preferably 10-60
In the range of μm, the dry film thickness of the base coat paint is 5
˜50 μm, preferably 8 to 20 μm.

Approximately 20 minutes between base coat and top coat
The temperature is 1 to 45 minutes, preferably 2 to 20 minutes. It is also possible to accelerate the coating interval time by forcibly drying the coating film of the base coat. The top coat may be applied after the base coat has been dried to the touch or to a semi-cured state under the above-mentioned drying conditions. After applying the top coat, it may be cured at a predetermined temperature and time. Forced drying at a temperature of 60 to 100 ° C. for about 10 to 60 minutes is preferable from the viewpoint of curability and productivity, but appropriate drying and curing conditions may be selected depending on the types and properties of base coat paint and top coat paint or materials. It can be changed.

As described above, the coating finishing method of the present invention can form a composite cured coating film having excellent coating film properties by drying at normal temperature or low temperature under the heat resistant temperature of ordinary plastic materials, A coating film having physical properties comparable to those of curable acrylic resin paints and aminoalkyd resin paints can be obtained. Further, the compositions [I] and [II] are one-pack type,
It has excellent storage stability and greatly contributes to the improvement of productivity.

Next, the present invention will be specifically described with reference to Production Examples, Examples and Comparative Examples, and all parts below are based on weight unless otherwise specified.

Reference Example 1 [Preparation of vinyl-based monomer (C)] In a four-necked flask equipped with a thermometer, a reflux condenser, a stirrer and a nitrogen gas inlet, 172 parts of methacrylic acid, 217 parts of trimethylchlorosilane and 2 parts of triethylamine were added.
Charge 02 parts, 25 ° C while paying attention to the rise of reaction temperature.
The reaction was continued for 1 hour. Then, the hydrochloride of triethylamine was passed through, and the liquid was purified by distillation under reduced pressure to obtain the desired vinyl monomer. Hereinafter, this vinyl-based monomer is abbreviated as [M-1].

Reference Example 2 [Preparation of vinyl-based monomer (C)] In a reactor similar to that of Reference Example 1, 144 parts of acrylic acid, 189 parts of dimethylchlorosilane and 20% of triethylamine were added.
The same operation as in Reference Example 1 was repeated except that 2 parts were reacted to obtain the desired vinyl monomer. Hereinafter, this vinyl-based monomer is abbreviated as [M-2].

Production Example 1 [Preparation of vinyl polymer] 300 parts of trimethylsiloxyethyl methacrylate,
200 parts of styrene, 400 parts of n- butyl methacrylate and acrylate esters SL (Mitsubishi Rayon Co., Ltd. C ₁₂ ~
200 parts of a monomer mixture consisting of 100 parts of a C ₁₃ alkyl group-containing methacrylate), 500 parts of toluene, 200 parts of isobutyl acetate, 5 parts of azobisisobutyronitrile (AIBN) and tert-butyl perbenzoate ( 10 parts of t-BPB) was charged into a four-necked flask equipped with a stirrer, an inert gas inlet, a thermometer and a condenser, and kept at 90 ° C. for 1 hour, then 30 minutes to 115 ° C. The temperature is raised, and at the same temperature, the remaining monomer mixture 800
Parts and isobutyl acetate 300 parts, t-BPB 10 parts and A
A mixture consisting of 5 parts of IBN was added dropwise over 3 hours,
Furthermore, the non-volatile content (hereinafter, N
A resin solution having a viscosity (abbreviated as V) of 49.8%, a viscosity (Gardner viscosity at 25 ° C .; the same hereinafter) YZ, a number average molecular weight (hereinafter abbreviated as n) 13000, and an OH number of 42 was obtained.

Hereinafter, this resin solution is abbreviated as [I-1].

Production Example 2 [Preparation of vinyl-based polymer] Triphenylsiloxyethyl methacrylate 250
Parts, methyl methacrylate 250 parts, styrene 150
Parts, 220 parts of n-butyl methacrylate and 130 parts of n-butyl acrylate were used in the same manner as in Production Example 1, except that NV 49.1%, viscosity X and n130 were obtained.
A resin solution having 0 and OH value of 18 was obtained.

Hereinafter, this resin solution is abbreviated as [I-2].

Production Example 3 [Preparation of vinyl-based polymer] 135 parts of trimethylsiloxyethyl methacrylate,
By the same operation as in Production Example 1 except that 510 parts of methyl metaacrylate, 350 parts of n-butyl methacrylate and 5 parts of n-butyl acrylate were used instead, NV50.
A resin solution having a viscosity of 8%, a viscosity Z, n15000 and an OH number of 19 was obtained.

Hereinafter, this resin solution is abbreviated as [I-3].

Production Example 4 [Preparation of vinyl polymer for comparison] Production Example 1 except that 195 parts of β-hydroxyethyl methacrylate, 200 parts of styrene, 505 parts of n-butyl methacrylate and 100 parts of Acryester SL were used instead. By the same operation, NV 50.0%, viscosity Z,
A resin solution having an n of 13,000 and an OH value of 42 was obtained.

Hereinafter, this resin solution is abbreviated as [I-4].

Production Example 5 [Preparation of vinyl-based polymer] 667 parts of xylene was charged in the same reactor as in Reference Example 1,
The temperature was raised to 110 ° C. 200 parts of styrene at that temperature, n-
Butyl methacrylate 443 parts, Acryester SL
[Vinyl polymer manufactured by Mitsubishi Rayon Co., Ltd.] 150 parts, 207 parts of [M-1] obtained in Reference Example 1, 10 parts of t-butylperoxyoctoate [abbreviated as TBPO hereinafter] and xylene 333. Part of the mixture was added dropwise over 4 hours. After that, the reaction was continued for 8 hours at the same temperature, NV50%, n13
000 resin solution was obtained.

Hereinafter, this resin solution is abbreviated as [II-1].

Production Examples 6 to 7 [Preparation of vinyl polymer] 200 parts of styrene, n-butyl methacrylate 443
Parts, Acryester SL 150 parts, [M-1] 207 and the same procedure as in Production Example 5 except that the amounts of the monomers and the initiators shown in Table 1 are used in place of TBPO, thereby repeating the procedure of Production Example 5. Got In Table 1, n is also shown.

Production Example 8 [Preparation of Vinyl-Based Polymer for Comparison] Instead of the vinyl-based monomer mixture used in Production Example 5, 200 parts of styrene and 590 parts of n-butyl methacrylate.
Acryester SL 100 parts and methacrylic acid 110
The same operation as in Production Example 5 was repeated except that parts were used,
A resin solution having an NV of 50% and n15,000 was obtained.

Hereinafter, this resin solution is abbreviated as [II-4].

Examples 1 to 5 and Comparative Examples 1 to 2 According to the compounding ratio (parts by weight) shown in Table 2, a topcoat paint and a basecoat paint were separately prepared by a conventional coating method, and xylene / toluene / Dilute to a spray viscosity with a mixed solvent of ethyl acetate = 30/50/20 (weight ratio), and apply a dry coating film of base coat and top coat of 15μ each to zinc phosphate treated steel sheet.
m and 10 μm, and paint by air spray with a coating interval of 2 kinds of paint for 2 minutes.
A cured coating film was obtained by heating at 30 ° C. for 30 minutes. Table 2 shows the results of evaluation of physical properties of the coating films thus obtained. The physical properties were evaluated after forced drying and leaving at room temperature for 3 days.

From the performance evaluation results shown in Table 2, compositions [I] and [II] were evaluated as 2
It can be seen that the physical properties of the cured coating film obtained after coating by the coating and one-bake coating finishing method are excellent, and that the coating composition is a one-pack type and has excellent long-term storage stability.

Claims (1)

[Claims] 1. A paint (base coat) containing a curable resin containing metallic powder and / or a coloring pigment as a main component.
Is applied, and then a clear coating (top coat) containing a curable resin as a main component is applied on the coated surface, and then the coating is cured. In the coating finishing method, at least one polymerizable unsaturated group and at least one polymerizable unsaturated group are contained in one molecule. Cured to a vinyl polymer comprising 1 to 100% by weight of a vinyl monomer (A) having one siloxy group and 99 to 0% by weight of a copolymerizable vinyl monomer (B) other than (A). A resin composition comprising an agent and a dissociation promoting catalyst, and [II] 1 to 1 of a vinyl-based monomer (C) having a polymerizable unsaturated group and at least one carboxysilane group in one molecule.
A resin composition comprising a vinyl polymer comprising 100% by weight and 0 to 99% by weight of a copolymerizable vinyl monomer (D) other than (C) with a curing agent and a dissociation promoting catalyst.
(However, [I] and [II] are not the same), one is used as a base paint and the other is used as a top paint.