JP3084736B2 - Resin composition for clear coat paint and laminating method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a novel and useful resin composition for a clear coat paint and a method for laminating the same using the same.

More specifically, the present invention relates to a vinyl copolymer (A) having a specific reactive group called 2-oxo-1,3-dioxolan-4-yl group and a quaternary ammonium salt (B).
Or the vinyl copolymer (A), a quaternary ammonium salt (B), and a specific compound (C) further having a carboxyl group and / or an acid anhydride group. A very useful clear coat paint resin composition having excellent coating appearance such as acid resistance, weather resistance and smoothness as a one-pack type paint composition having excellent storage stability, and a method of laminating using the same. About.

[Prior Art] In recent years, there is a strong need for an excellent finished appearance, mainly in the automobile industry.

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

In view of such a problem, development of a novel curing mode resin has been studied.

Among them, 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 There are systems based on combinations, and 4) systems based on moisture-curable resins having hydrolyzable silyl groups.

However, among 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, and 2).
In the case of using a combination of a silanol group-containing resin and an epoxy group-containing resin, or 3) 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 causes There are various disadvantages such as a change in film performance and an unsatisfactory appearance.

[Problems to be Solved by the Invention] Furthermore, in addition to such long-term storage stability and appearance of the coating film, it is possible to obtain a coating film that can withstand acid rain, especially in the automobile industry. There is an urgent need for rapid development of useful curing systems.

For this purpose, the present inventors have eagerly started research to meet the above-mentioned demands.

That is, the problem to be solved by the present invention is a one-pack type coating resin composition having excellent storage stability, and also having an excellent coating appearance such as acid resistance, weather resistance and smoothness. It is an object of the present invention to provide a useful resin composition for a clear coat paint, and a method for applying a laminate using the same.

[Means for Solving the Problems] The inventors of the present invention focused on the problems to be solved by the invention as described above and conducted intensive studies. As a result, 2-oxo-1,3-dioxolan-4- Resin composition for clear coat paints comprising a vinyl copolymer having an yl group (A) and a quaternary ammonium salt (B) which is a ring-opening catalyst for the 2-oxo-1,3 and dioxolan-4-yl groups Or a compound having a carboxyl group and / or an acid anhydride group, and the vinyl copolymer (A),
A resin composition for a clear coat paint, comprising a compound (C) other than the vinyl copolymer (A) as an essential film-forming component and further incorporating a quaternary ammonium salt (B), It has been found that a one-pack type paint having excellent stability and good workability can be obtained, and a coating film having not only acid resistance but also excellent weather resistance and coating film appearance can be obtained. Thus, the present invention has been completed.

That is, the present invention provides, as an essential component, at least two compounds represented by the general formula Or a quaternary ammonium salt (B) mixed with a vinyl copolymer (A) having a 2-oxo-1,3-dioxolan-4-yl group represented by 2-oxo-1,3-dioxolan-4-
A compound having at least two carboxyl groups and / or acid anhydride groups per molecule in a vinyl copolymer (A) containing an yl group, and a compound (C) other than the vinyl copolymer (A) ) And a quaternary ammonium salt (B), and at least two 2-oxo-1,3-dioxolan-4-yl groups in one molecule. Having vinyl copolymer (A)
And at least one compound selected from the group consisting of vinyl copolymers, polyester resins and low molecular weight compounds having at least two carboxyl groups and / or acid anhydride groups in one molecule, wherein the vinyl An object of the present invention is to provide a resin composition for a clear coat paint containing a compound other than the copolymer (A) and a quaternary ammonium salt (B). It is an object of the present invention to provide a laminate coating method using the clear coat paint.

In the present invention, the term “laminated coating” refers to, for example, first applying a crosslinkable basecoat paint containing a glitter 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 coat paint I) is applied on the painted surface and crosslinked; or a thermosetting paint is obtained on the thus-obtained laminated coating. Clear coat paint (clear paint
II) So-called 3 coats 2 which are painted and crosslinked
A coating method by a baking method; or first, a crosslinkable base coat paint in the form of a mixture of a luminous agent and / or a color pigment is applied on an object (substrate) to be crosslinked,
Then, a thermosetting clear coat paint is applied on the base coat paint surface and crosslinked, so-called 2
It refers to various systems based on a coating method using a coat 2 bake method.

At least two 2-oxo-1,
The vinyl copolymer (A) having a 3-dioxolan-4-yl group (hereinafter also referred to as a cyclocarbonate group) includes, for example, at least one polymerizable unsaturated double bond in one molecule. Compound (a-1) having one 2-oxo-1,3-dioxolan-4-yl group in combination
And another polymerizable unsaturated monomer copolymerizable with the compound (a-1) by a conventional method. Alternatively, the compound (a-1) may be obtained by copolymerization with 2-oxo-1,2, such as glyceryl carbonate.
It can also be obtained by adding a compound (a-2) having both a 3-dioxolan-4-yl group and a hydroxyl group to a vinyl copolymer having a functional group capable of reacting with the hydroxyl group.

In particular, it can be copolymerized with a compound (a-1) in which one polymerizable unsaturated double bond and at least one 2-oxo-1,3-dioxolan-4-yl group are combined in one molecule. A simple method is to obtain a polymerizable unsaturated monomer (a-2) by copolymerization with a conventional method.

As the functional groups capable of reacting with the above-mentioned hydroxyl groups, only typical ones may be mentioned, and examples thereof include an isocyanate group, an acid anhydride group and an acid chloride.

One polymerizable unsaturated diol in one molecule used for obtaining a vinyl copolymer (1) containing at least two 2-oxo-1,3-dioxolan-4-yl groups in one molecule. A heavy bond and at least one 2-oxo-1,
Compound having a 3-dioxolan-4-yl group (a-
As 1), for example, a general formula And so on. Specifically, 2,3-carbonatepropyl (meth) acrylate, 3,4-carbonatebutyl (meth) acrylate, 4,5-carbonatepentyl (meth) acrylate, 6,7-carbonatehexyl (meth) acrylate, 2 , 3-carbonatepropyl vinyl ether or methyl-2,3-carbonatepropylcrotonate.

The amount of the compound (a-1) to be used is 1 to 50
A suitable range is 5 parts by weight, preferably 5 to 35 parts by weight. If the amount is less than 1 part by weight, crosslinking is insufficient when forming a coating film, and sufficient coating film performance cannot be exhibited. On the other hand, if it exceeds 50 parts by weight, a hard and brittle coating film is formed, which is not preferable. .

Further, another polymerizable unsaturated monomer (a) copolymerizable with the unsaturated monomer (a-1) containing a cyclocarbonate group.
Although -2) is not particularly limited, it may be further copolymerized with an unsaturated monomer having a hydroxyl group and / or a carboxyl group as a functional group, but the effect of the present invention can be further enhanced. Recommended because you can.

Particularly typical examples of such hydroxyl group-containing unsaturated monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxypropyl (meth) acrylate. Hydroxyalkyl (meth) acrylates such as hydroxybutyl (meth) acrylate; hydroxyalkyl vinyl ethers such as 2-hydroxyethyl vinyl ether and 4-hydroxybutyl vinyl ether; or allyl compounds such as allyl alcohol or hydroxyethyl aryl ether; And a hydroxyl group-containing unsaturated monomer obtained by adding ε-caprolactone to the above monomer.

The introduction of the hydroxyl group causes a reaction with the cyclocarbonate group, which also induces an increase in the crosslink density, and as a result,
Solvent resistance and weather resistance are improved.

Further, a carboxyl group-containing unsaturated monomer can also be used.

When such a carboxyl group-containing unsaturated monomer is used,
This is particularly effective because the compatibility with the carboxyl group and / or acid anhydride group-containing compound (C) is significantly improved.

As the carboxyl group-containing unsaturated monomer used in the present invention, only particularly typical ones are exemplified, and α, β unsaturated monomonomers such as (meth) acrylic acid, maleic acid, fumaric acid and itaconic acid can be used. -Or dicarboxylic acids; or ester compounds of α, β-ethylenically unsaturated dicarboxylic acids and monohydric alcohols having 1 to 4 carbon atoms, such as monoethyl maleate, monobutyl maleate, monobutyl fumarate or monoethyl itaconate; Further, there is a carboxyl group-containing unsaturated monomer obtained by adding an acid anhydride such as phthalic anhydride to a hydroxyl group-containing vinyl monomer such as 2-hydroxyethyl (meth) acrylate.

As other copolymerizable vinyl monomers (a-2), only typical ones may be mentioned, for example, alkyl (meth) acrylate having an alkyl group having 1 to 22 carbon atoms, 2-ethoxy, (Meth) acrylates such as ethyl (meth) acrylate, cyclohexyl (meth) acrylate or (meth) acrylonitrile;
A basic nitrogen atom-containing compound such as glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, (meth) acrylamide or N-alkoxymethylated (meth) acrylamide; a phosphoric acid group-containing (meth) acrylate; Reactive group-containing (meth) acrylates such as silyl group-containing (meth) acrylates; or aromatic vinyl monomers such as styrene, tert-butylstyrene, α-methylstyrene or vinyltoluene; vinyl fluoride, tetrafluoro Examples thereof include fluorine-containing vinyl monomers such as ethylene and hexafluoropropylene.

And at least two 2-oxo-1,
In order to prepare the vinyl copolymer (A) containing a 3-dioxolan-4-yl group, a conventional method such as a solution polymerization method or a non-aqueous dispersion polymerization method may be used. Is the most convenient.

If only typical solvents are exemplified here, toluene, xylene, cyclohexane, n-hexane, octane, “Solvesso 10
Hydrocarbon solvents such as "0" or "Solvesso 150" (an aromatic hydrocarbon solvent manufactured by Exxon Chemical Co.); esters such as methyl acetate, butyl acetate, amyl acetate, ethyl ethoxy propionate or ethoxy propionate acetate There are ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone and cyclohexanone, but these may be used alone or in combination of two or more.

If only typical radical polymerization initiators are mentioned, azo-based initiators represented by azobisisobutyronitrile or peroxide-based initiators represented by benzoyl peroxide are used.

Further, if necessary, various chain transfer agents such as lauryl mercaptan, octyl mercaptan, 2-mercaptoethanol, octyl thioglycolate, 3-mercaptopropionic acid or α-methylstyrene dimer can be used as a molecular weight regulator.

The number average molecular weight of the vinyl copolymer (A) thus obtained is preferably in the range of 800 to 50,000 from the viewpoint of coating film performance and coating workability.

Next, as the compound (C) containing a carboxyl group and / or an acid anhydride group, at least one selected from the group consisting of a vinyl copolymer, a polyester resin, and a low molecular compound having such a specific functional group. Can be used.

Specifically, first, as the vinyl copolymer, a carboxyl group-containing unsaturated monomer and / or an acid anhydride group-containing unsaturated monomer can be copolymerized with another unsaturated monomer as described above. Those obtained by copolymerizing with (a-2) may be used.

As the carboxyl group-containing unsaturated monomer, of course, those described above are used.

As the acid anhydride group-containing unsaturated monomer, a monomer having both an acid anhydride group represented by maleic anhydride and itaconic anhydride and a polymerizable unsaturated double bond is used.

Examples of the unsaturated monomer capable of copolymerization with the unsaturated monomer having a carboxyl group and / or the unsaturated monomer having an acid anhydride group include the above-mentioned unsaturated monomer having a cyclocarbonate group (a-1). ) And other unsaturated monomers (a-
Those listed as 2) can also be used.

Next, as the carboxyl group-containing polyester resin, those obtained by excessively reacting an acid component with a polyhydric alcohol, or those obtained by reacting an acid anhydride compound with a hydroxyl group-containing polyester resin are exemplified. .

Specific examples of the polyester resin include phthalic acid, hexahydrophthalic acid, isophthalic acid, adipic acid, maleic acid or polyvalent carboxylic acid represented by dimer acid, and ethylene glycol, propylene glycol, neopentyl glycol or It can be obtained by condensation with a polyhydric alcohol such as trimethylolpropane by a known and commonly used method.

Further, it is obtained by adding an acid anhydride group-containing compound such as trimellitic acid to the hydroxyl group in the polyester resin, and can be obtained even when the reaction is carried out under the condition that the polycarboxylic acid becomes excessive.

Next, examples of the carboxyl group-containing low molecular weight compound include adipic acid, phthalic acid, isophthalic acid and dimer acid, and the like. Particularly, if the compound contains two or more carboxyl groups in one molecule, It is not limited.

On the other hand, as acid anhydride group-containing low molecular weight compounds, trimellitic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, heptonic anhydride, hymic anhydride, maleic anhydride, itaconic anhydride, pyromellitic anhydride, glycerol tris ( Trimellitate) or ethylene glycol di (trimellitate).

Further, the quaternary ammonium salt (B) used as a catalyst for ring opening of the cyclocarbonate group will be described. The quaternary ammonium salt (B) is an important component for the decarbonation reaction from the cyclocarbonate group. Particularly, only typical examples are exemplified by tetramethylammonium fluoride, trimethylbenzylammonium hydroxide or trimethylbenzylammonium methoxide.

The amount of the quaternary ammonium salt (B) to be used is set to 100% of the solid content of the above-mentioned vinyl copolymer (A).
The range of 0.01 to 5 parts by weight with respect to parts by weight is appropriate.

If the amount used is less than 0.01 part by weight when baking for about 20 minutes at a temperature range of 120 to 160 ° C., the crosslinking reaction cannot proceed sufficiently, and if it exceeds 5 parts by weight. In this case, a problem occurs in the storage stability of the paint and the water resistance of the cured coating film is deteriorated.

Further, an epoxy group ring-opening catalyst can also be used to promote the reaction between the epoxy group and the carboxyl group generated by the decarbonation reaction of the cyclocarbonate group. For the purpose of the present invention, it is preferable to use a basic catalyst which is usually used.

Examples of such a basic catalyst include the aforementioned quaternary ammonium salts and quaternary phosphonium salts, and further, tertiary organic phosphorus compounds represented by triphenylphosphine.

The amount of the epoxy group-opening catalyst used is 5 parts by weight based on 100 parts by weight of the solid content of the vinyl copolymer (A).
It is preferably within the range of not more than part by weight.

If necessary, known and commonly used additives such as a leveling agent and an ultraviolet absorber can be added to the thus obtained resin composition for a laminated paint of the present invention.

Further, the composition of the present invention may be added with known and commonly used cellulose-based additives, plasticizers or polyester resins.

Thus, the composition of the present invention is used as a top clear coat when performing a so-called lamination coating in which a coating film is formed by a two-coat one-bake method or a two-coat two-bake method, and further by a three-coat two-bake method. be able to.

At this time, the coating composition for the base coat is not particularly limited, and may be any composition that can form a coating film.

If only particularly typical examples are given as the base coat composition, a hydroxyl group-containing resin and a melamine resin, a hydroxyl group-containing resin and a polyisocyanate, a carboxyl group-containing resin and an epoxy group-containing resin, a hydrolyzable silyl group-containing resin, and the like. Also, there are those obtained by combining at least one of organic, inorganic and metal pigments with a mixture of two or more of these.

〔Example〕

Next, the present invention by reference examples, examples and comparative examples,
This will be described more specifically. In the following, parts and%
All are by weight unless otherwise noted.

Reference Example 1 [Preparation Example of Cyclocarbonate Group-Containing Vinyl Copolymer (A)] In a four-necked flask equipped with a thermometer, a cooling pipe, a stirrer, and a nitrogen gas inlet pipe, 500 parts of xylene and n-butanol were added. Charge 300 parts, to the place where the temperature was raised to 120 ℃, 300 of 2,3-carbonate propyl methacrylate
Parts, 200 parts of methyl methacrylate, 200 parts of styrene and 300 parts of n-butyl methacrylate, and 200 parts of xylene, azobisisobutyronitrile (A
A mixture of 10 parts of IBN) and 20 parts of tert-butylperoxy-2-ethylhexanoate was added dropwise at the same temperature over 5 hours, and after completion of the addition, the mixture was maintained at the same temperature for 7 hours. The reaction was performed to obtain a resin solution having a nonvolatile content of 50.4%, a Kardner viscosity at 25 ° C (hereinafter abbreviated as viscosity) of MN, and a number average molecular weight of 11,000. Less than,
This is abbreviated as resin (A-1).

Reference Example 2 (same as above) As a monomer mixture, 250 parts of 2,3-carbonate butyl acrylate, 150 parts of styrene, 350 parts of isobutyl methacrylate, 150 parts of 2-ethylhexyl methacrylate, 2,3-carbonate propyl Acrylate
A resin having a non-volatile content of 50.6% and a viscosity of X was obtained in the same manner as in Reference Example 1, except that a mixture consisting of 50 parts and 50 parts of methacrylic acid was used. Less than,
This is abbreviated as resin (A-2).

Reference Example 3 [Preparation example of carboxyl group-containing vinyl resin (C)] 300 parts of acrylic acid, 300 parts of styrene and 400 parts of n-butyl methacrylate were used as a monomer mixture, and AIBN was used as an initiator. 10 parts and tert-
A resin having a nonvolatile content of 50.2% and a viscosity of O was obtained in the same manner as in Reference Example 1 except that 70 parts of butylpa-2-ethylhexanoate was used. Less than,
This is abbreviated as resin (C-1).

Reference Example 4 [Preparation Example of Carboxyl Group-Containing Polyester Resin (C)] In 500 parts of "Placcel 308" (caprolactone polymerization polyol manufactured by Daicel Chemical Co., Ltd.), 87 parts of phthalic anhydride and 100 parts of xylene were further added. And butyl acetate 5
After charging 0 parts, the reaction was carried out at 120 ° C. for 2 hours to obtain a resin solution having a nonvolatile content of 80% and a viscosity of Q. Hereinafter, this is abbreviated as resin (C-2).

Examples 1 to 5 Using the respective resins obtained in Reference Examples 1 to 4, according to the mixing composition ratios shown in Table 1, the compositions for laminated coating resins of the present invention were obtained.

Further, the performance of the coating film obtained by two-coat two-bake or two-coat two-bake finishing, respectively, was evaluated using the thus obtained resin composition for lamination coating as a top coat.

 The results are shown in Table 2.

Footnotes in Table 1 The paint composed of acrylic resin / melamine resin used in Comparative Example 3 was “Acrydic 52-748” (a hydroxyl group-containing acrylic resin manufactured by Dainippon Ink and Chemicals, Inc.)
"Super Beckamine L-117-60" (butyl etherified melamine resin manufactured by the same company) was blended at a ratio of 70:30 (solids weight ratio).

In addition, base paint; A is "Acridic 47-71
2 "(Hydroxy group-containing acrylic resin manufactured by Dainippon Ink and Chemicals, Inc.)," Super Beckamine L-117-60 "and" Aluminum Paste 7160NS "(aluminum paste manufactured by Toyo Aluminum Co., Ltd.) Base paint.

B is a base paint containing “Beccolite GF-542” (a hydroxyl group-containing polyester resin manufactured by Dainippon Ink and Chemicals, Inc.), “Super Beckamine L-117-60” and carbon black (PWC = 3%). . C is a hydroxyl group-containing emulsion resin (composition = styrene: methyl methacrylate: butyl acrylate: methacrylic acid: 2-hydroxypropyl methacrylate = 10: 40: 43: 2: 5, nonvolatile content = 40
%), "Cymel C-325" (Methyl etherified melamine resin manufactured by Mitsui Cyanamid Co., Ltd.), Primal ASE-60 "(polycarboxylic acid emulsion manufactured by Nippon Acrylic Chemical Co., Ltd.) and" Aluminum paste WZ71
Aqueous metallic base paint containing "60" (aluminum paste manufactured by the same company). D is a metallic base paint containing the paint composition of Example 1 and aluminum paste 7160NS.

Further, Example 4 is a case in which the two-coat two-base finishing method is used.
The coating film was formed by the coating 1 baking finishing method.
The baking conditions are all 140 ° C. for 20 minutes.

〔The invention's effect〕

The resin composition for laminate coating of the present invention, and the paint finishing method using them, that is, the laminate coating method of the present invention has excellent storage stability as a one-pack type paint, and therefore has good workability. Needless to say, the coating film obtained by the coating finishing method of the present invention is excellent in acid resistance, weather resistance, and appearance of the coating film, particularly, smoothness.

Therefore, it can be said that both the resin composition for layer coating of the present invention and the layer coating method using the same will open up a new field of automobile coating.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI C09D 133/14 C09D 133/14 (56) References JP-A-1-225675 (JP, A) JP-A-1-146966 (JP) JP-A-2-53880 (JP, A) JP-A-1-146968 (JP, A) JP-A-2-302458 (JP, A) JP-A-57-202318 (JP, A) 57-202317 (JP, A) JP-A-2-208303 (JP, A) JP-A-2-2866 (JP, A) JP-A-3-103478 (JP, A) JP-A-2-208350 (JP, A A) Patent 2789662 (JP, B2) Patent 3041922 (JP, B2) EP 1088 (EP, A1) EP 337926 (EP, A2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 1/00-201/10 B05D 1/00-7/26 C08F 8/00-8/50 CA (STN) REG STRY (STN) WPI / L (QUESTEL)

Claims (8)

(57) [Claims] (1) at least two general formulas per molecule A quaternary ammonium salt (B) mixed with a vinyl copolymer (A) having a 2-oxo-1,3-dioxolan-4-yl group represented by the formula: Stuff. 2. A compound represented by at least two general formulas per molecule Is a compound having at least two carboxyl groups and / or acid anhydride groups in one molecule to the vinyl copolymer (A) containing a 2-oxo-1,3-dioxolan-4-yl group represented by And a compound (C) other than the vinyl copolymer (A) and a quaternary ammonium salt (B). 3. The compound (C) is selected from the group consisting of a vinyl copolymer, a polyester resin and a low molecular compound having at least two carboxyl groups and / or acid anhydride groups in one molecule. The resin composition for a clear coat paint according to claim 2, which is at least one compound. 4. A compound represented by the general formula: A clear coating is applied to a coating comprising a resin composition obtained by blending a quaternary ammonium salt (B) with a vinyl copolymer (A) having a 2-oxo-1,3-dioxolan-4-yl group represented by A laminated coating method characterized by being used as a paint. 5. A compound represented by the general formula: Is a compound having at least two carboxyl groups and / or acid anhydride groups in one molecule to the vinyl copolymer (A) containing a 2-oxo-1,3-dioxolan-4-yl group represented by Wherein a paint comprising a resin composition obtained by blending a compound (C) other than the vinyl copolymer (A) with a quaternary ammonium salt (B) is used as a clear coat paint. Lamination coating method. 6. The compound (C) is selected from the group consisting of a vinyl copolymer, a polyester resin and a low molecular compound having at least two carboxyl groups and / or acid anhydride groups in one molecule. The method according to claim 5, wherein the compound is at least one compound. 7. The method according to claim 4, wherein said multi-layer coating is based on a two-coat one-bake method. 8. The method according to claim 4, 5 or 6, wherein the lamination is performed by a two-coat two-bake method.