JP5936448B2 - Coating composition and coated article - Google Patents

Description

  The present invention relates to a coating composition and a coated article containing silica particles having a modified surface.

  Conventionally, as automotive clearing coating compositions, there are melamine crosslinking coating compositions using a hydroxyl group-containing resin and a melamine resin as a crosslinking agent, and urethane crosslinking coating compositions using a polyisocyanate compound as a crosslinking agent. It is widely used. On the other hand, automobile users who place emphasis on the appearance are desired to take preventive measures such as scratches (scratch resistance) caused by a car washer of the automobile and scratches around the keyhole (scratch resistance). Furthermore, automotive clear coatings are not limited to car wash scuff resistance and scratch resistance around keyholes, but also impact resistance, weather resistance, finish (appearance such as transparency and glossiness), adhesion, etc. It is necessary to combine coating film performance, and it is required to improve the scratch resistance of the coating film without degrading other performances of the coating film.

  On the other hand, as a method for improving the scratch resistance of a coating film, a method of adding silica particles to a coating composition is known. It is also known to use colloidal silica or nanosilica particles when a coating film having high transparency and high wear resistance is required.

  The present applicant, in Patent Document 1, contains a thermosetting resin composition and colloidal silica having a solid content of less than 3 to 10 parts by mass per 100 parts by mass of resin solids of the resin composition. A solvent-based thermosetting coating composition is proposed. This paint has excellent scratch resistance because of its high surface hardness due to the effect of colloidal silica, but depending on the resin applied, the dispersibility of the silica particles may be reduced and transparency may be insufficient. .

  Patent Document 2 discloses a composition containing polysiloxane-modified silica particles. This composition can improve the scratch resistance of the cured coating film, but when used in a melamine cross-linking coating composition, the dispersibility of the silica particles is lowered and the transparency may be insufficient. there were.

JP 2000-136332 A JP 2006-290725 A

  An object of the present invention is to provide a coating composition that can impart excellent scratch resistance to the resulting cured coating film without lowering the finish such as transparency and gloss, and a coated article thereof. is there.

  As a result of intensive studies to solve the above problems, the present inventors have a hydrolyzable silane compound (ai) having an isocyanurate ring structure represented by the general formula (I) and an isocyanurate ring structure. By using a coating composition containing silica particles (A) having a surface modified with a hydrolyzable silane compound (a) containing a hydrolyzable silane compound (a-ii) and a binder component (B) The present inventors have found that the problem can be solved and have completed the present invention.

That is, the present invention provides the coating composition and coated article of the following section:
Item 1. A coating composition comprising silica particles (A) having a surface modified with a hydrolyzable silane compound (a) and a binder component (B),
The hydrolyzable silane compound (a) has the following general formula (I)

［式（Ｉ）中、Ｘ^１、Ｘ^２及びＸ^３は加水分解性シリル基又は水酸基を示し、これらのうち少なくとも１つは加水分解性シリル基であり、Ｒ^１、Ｒ^２及びＲ^３は同一、又は異なって２価の有機基を示す。］で表されるイソシアヌレート環構造を有する加水分解性シラン化合物（ａ−ｉ）、及び下記一般式（ＩＩ）

[In the formula (I), X ¹ , X ² and X ³ represent a hydrolyzable silyl group or a hydroxyl group, and at least one of them is a hydrolyzable silyl group, and R ¹ , R ² and R ³ are It is the same or different and represents a divalent organic group. And a hydrolyzable silane compound (ai) having an isocyanurate ring structure represented by the following general formula (II):

［式（ＩＩ）中、Ｒ^４は、炭素数１〜１８の１価の炭化水素基を示す。Ｒ^ａ、Ｒ^ｂ及びＲ^ｃのうち少なくとも１つは、ハロゲン原子、ヒドロキシ基、アルコキシ基又はアリールオキシ基を示し、残余は水素原子、アルキル基又はアリール基を示す。］で表されるイソシアヌレート環構造を有さない加水分解性シラン化合物（ａ−ｉｉ）を含むことを特徴とする塗料組成物。

[In Formula (II), R ⁴ represents a monovalent hydrocarbon group having 1 to 18 carbon atoms. At least one of R ^a , R ^b and R ^c represents a halogen atom, a hydroxy group, an alkoxy group or an aryloxy group, and the remainder represents a hydrogen atom, an alkyl group or an aryl group. ] The coating composition characterized by including the hydrolysable silane compound (a-ii) which does not have the isocyanurate ring structure represented by these.

Item 2. The hydrolyzable silane compound (ai) is
Compound represented by the following general formula (III) and / or compound represented by the following general formula (IV)

［式（ＩＩＩ）中、Ｒ^５は同一、又は異なって炭素数が２〜１１の２価の炭化水素基を示す。Ｒ^ａ、Ｒ^ｂ及びＲ^ｃは前記と同じである。］

[In formula (III), R ⁵ is the same or different and represents a divalent hydrocarbon group having 2 to 11 carbon atoms. R ^a , R ^b and R ^c are the same as described above. ]

［式（ＩＶ）中、Ｒ^６は同一、又は異なって炭素数が２〜１１の２価の炭化水素基を示す。ｍは同一、又は異なって０〜５の整数を示す。Ｒ^ａ、Ｒ^ｂ及びＲ^ｃのうち少なくとも１つは、ハロゲン原子、ヒドロキシ基、アルコキシ基又はアリールオキシ基を示し、残余は水素原子、アルキル基又はアリール基を示す。］であるイソシアヌレート環構造を有する加水分解性シラン化合物であることを特徴とする項１に記載の塗料組成物。

[In formula (IV), R ⁶ is the same or different and represents a divalent hydrocarbon group having 2 to 11 carbon atoms. m is the same or different and represents an integer of 0 to 5. At least one of R ^a , R ^b and R ^c represents a halogen atom, a hydroxy group, an alkoxy group or an aryloxy group, and the remainder represents a hydrogen atom, an alkyl group or an aryl group. Item 2. The coating composition according to Item 1, which is a hydrolyzable silane compound having an isocyanurate ring structure.

  Item 3. The compound represented by the general formula (IV) is obtained by reacting a compound represented by the following general formula (V) with a compound represented by the following general formula (VII), and / or It is a compound obtained by reacting a compound represented by the following general formula (V), a compound represented by the following general formula (VI), and a compound represented by the following general formula (VII). Item 3. The coating composition according to Item 1 or 2,

［式（Ｖ）中、Ｒ^６は同一、又は異なって炭素数２〜１１の２価の炭化水素基を示す。］

[In formula (V), R ⁶ is the same or different and represents a divalent hydrocarbon group having 2 to 11 carbon atoms. ]

［式（ＶＩ）中、Ｚは炭素原子数２〜１４の２価の飽和炭化水素基を示す。］

[In the formula (VI), Z represents a divalent saturated hydrocarbon group having 2 to 14 carbon atoms. ]

［式（ＶＩＩ）中、Ｒ^７は炭素数１〜４の２価の炭化水素基を示す。Ｒ^ａ、Ｒ^ｂ及びＲ^ｃのうち少なくとも１つは、ハロゲン原子、ヒドロキシ基、アルコキシ基又はアリールオキシ基を示し、残余は水素原子、アルキル基又はアリール基を示す。］
項４．加水分解性シラン化合物（ａ−ｉ）と加水分解性シラン化合物（ａ−ｉｉ）の含有比は、加水分解性シラン化合物（ａ−ｉ）／加水分解性シラン化合物（ａ−ｉｉ）＝０．０５〜５．０（質量比）である項１〜３のいずれか１項に記載の塗料組成物。

[In Formula (VII), R ⁷ represents a divalent hydrocarbon group having 1 to 4 carbon atoms. At least one of R ^a , R ^b and R ^c represents a halogen atom, a hydroxy group, an alkoxy group or an aryloxy group, and the remainder represents a hydrogen atom, an alkyl group or an aryl group. ]
Item 4. The content ratio of the hydrolyzable silane compound (ai) to the hydrolyzable silane compound (a-ii) is such that hydrolyzable silane compound (ai) / hydrolyzable silane compound (a-ii) = 0. Item 5. The coating composition according to any one of Items 1 to 3, which is 05 to 5.0 (mass ratio).

  Item 5. Item 5. The coating composition according to any one of Items 1 to 4, wherein the surface-modified silica particles (A) are obtained by reacting silica fine particles (s) with a hydrolyzable silane compound (a). .

  Item 6. Item 6. The coating composition according to any one of Items 1 to 5, wherein the average primary particle size of the silica fine particles (s) is 1 to 50 nm.

  Item 7. Item 7. The coating composition according to Item 5 or 6, wherein the hydrolyzable silane compound (a) has a solid content of 1 to 55 parts by mass based on 100 parts by mass of silica fine particles (s).

  Item 8. Item 8. The coating composition according to any one of Items 1 to 7, wherein the binder component (B) contains a hydroxyl group-containing resin (Bi) and a crosslinking agent (B-ii).

  Item 9. The solid content of the silica particles (A) whose surface is modified is 1 to 200% by mass with respect to the total resin solid content of the binder component (B), 2. The coating composition according to item 1.

  Item 10. Item 10. The coating composition according to any one of Items 1 to 9, which is a coating composition for topcoat clear topcoat.

  Item 11. Item 11. A coated article obtained by coating the coating composition according to any one of items 1 to 10.

  According to the present invention, a hydrolyzable silane compound (ai) having an isocyanurate ring structure represented by the general formula (I) and a hydrolyzable silane compound (a-ii) having no isocyanurate ring structure By using the silica particles (A) whose surface is modified with a hydrolyzable silane compound (a) containing, the resulting cured coating film has excellent resistance to resistance without reducing the finish such as transparency and glossiness. A coating composition capable of imparting scratching properties can be obtained.

  According to the present invention, since the compatibility of the binder component (B) and the silica particles is improved by using the silica particles (A) whose surfaces are modified with the specific hydrolyzable silane compound (a), silica The particles are uniformly dispersed, and the cured coating film has the effect of having excellent scratch resistance without impairing the finish such as transparency and glossiness.

≪Silica particles with modified surface (A) ≫
The coating composition of the present invention contains silica particles (A) whose surfaces are modified with a hydrolyzable silane compound (a).

  Examples of the raw material for the silica particles (A) whose surface is modified include silica fine particles (s) such as colloidal silica fine particles and powdery fine particle silica.

  Colloidal silica fine particles are obtained by dispersing ultrafine particles of silica in a dispersion medium.

  As a dispersion medium, water; alcohol solvents such as methanol, ethanol, isopropanol, n-propanol, isobutanol, n-butanol; polyhydric alcohol solvents such as ethylene glycol; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, etc. Polyhydric alcohol derivatives; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and diacetone alcohol; monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and tetrahydrofurfuryl acrylate. Of these, water, methanol, ethanol, isopropanol and the like are preferable from the viewpoint of ease of production.

  Colloidal silica fine particles include methanol silica sol, IPA-ST, MEK-ST, NBA-ST, XBA-ST, DMAC-ST, PGM-ST, SNOWTEX UP, OUP, 20, 40, 40-O, C, N , O, 50, OL (trade name, manufactured by Nissan Chemical Industries, Ltd.) and the like.

  Commercially available powdered fine-particle silicas include Aerosil 130, Aerosil 300, Aerosil 380, Aerosil TT600, Aerosil OX50 (above, trade name, made by Nippon Aerosil Co., Ltd.), E220A, E220 (above, trade name, made by Nippon Silica Kogyo Co., Ltd.) ), SYLYSIA470 (above, trade name, manufactured by Fuji Silysia Chemical Ltd.) and the like.

  The average primary particle diameter of the silica fine particles (s) is preferably 1 to 50 nm, preferably 8 to 40 nm from the viewpoint of suppressing gelation when reacted with the hydrolyzable silane compound (a) and the transparency of the cured coating film. Is more preferable.

  In the present invention, the average primary particle diameter is a median diameter (d50) of a volume-based particle size distribution measured by a dynamic light scattering method, and is measured using, for example, a nanotrack particle size distribution measuring apparatus manufactured by Nikkiso Co., Ltd. Can do.

≪Hydrolyzable silane compound (a) ≫
The hydrolyzable silane compound (a) used in the coating composition of the present invention includes a hydrolyzable silane compound (ai) having an isocyanurate ring structure represented by the general formula (I), and the general formula (II) And a hydrolyzable silane compound (a-ii) having no isocyanurate ring structure.
This will be described in detail below.
Hydrolyzable silane compound (ai)
The hydrolyzable silane compound (ai) has the following general formula (I)

［式（Ｉ）中、Ｘ^１、Ｘ^２及びＸ^３は加水分解性シリル基、又は水酸基を示し、これらのうち少なくとも１つは加水分解性シリル基であり、Ｒ^１、Ｒ^２及びＲ^３は同一、又は異なって２価の有機基を示す。］で表されるイソシアヌレート環構造を有するものである。

[In Formula (I), X ¹ , X ² and X ³ represent a hydrolyzable silyl group or a hydroxyl group, and at least one of them is a hydrolyzable silyl group, and R ¹ , R ² and R ³ Are the same or different and represent a divalent organic group. ] It has an isocyanurate ring structure represented by this.

The hydrolyzable silane compound (ai) has a hydrolyzable silyl group.
The hydrolyzable silyl group is a silanol group or a group that generates a silanol group by hydrolysis. Examples of the group that forms a silanol group include groups in which an alkoxy group, an aryloxy group, an acetoxy group, a halogen atom, or the like is bonded to a silicon atom. Here, the alkoxy group is preferably an alkoxy group having 1 to 8 carbon atoms, and the aryloxy group is preferably an aryloxy group having 6 to 18 carbon atoms. A halogen atom includes chlorine.

R ¹ , R ² and R ³ are divalent organic groups. As a bivalent organic group, a C1-C100 bivalent organic group is mentioned, for example. From the point of the hardness of the cured coating film obtained, Preferably it is a C1-C30 bivalent organic group. The divalent organic group is not limited to a hydrocarbon group, and may have, for example, a urethane bond, an ester bond, an ether bond, or the like.

  In the coating composition of the present invention, the hydrolyzable silane compound (ai) is a compound represented by the following general formula (III) and / or a compound represented by the following general formula (IV).

［式（ＩＶ）中、Ｒ^５は同一、又は異なって炭素数が２〜１１の２価の炭化水素基を示す。Ｒ^ａ、Ｒ^ｂ及びＲ^ｃのうち少なくとも１つは、ハロゲン原子、ヒドロキシ基、アルコキシ基又はアリールオキシ基を示し、残余は水素原子、アルキル基又はアリール基を示す。］。

[In formula (IV), R ⁵ is the same or different and represents a divalent hydrocarbon group having 2 to 11 carbon atoms. At least one of R ^a , R ^b and R ^c represents a halogen atom, a hydroxy group, an alkoxy group or an aryloxy group, and the remainder represents a hydrogen atom, an alkyl group or an aryl group. ].

［式（ＩＶ）中、Ｒ^６は同一、又は異なって炭素数が２〜１１の２価の炭化水素基を示す。ｍは同一、又は異なって０〜５の整数を示す。Ｒ^ａ、Ｒ^ｂ及びＲ^ｃは前記と同じである。］であるイソシアヌレート環構造を有する加水分解性シラン化合物であることが、シリカ粒子の分散性及びバインダー成分（Ｂ）との相溶性の点から好ましい。

[In formula (IV), R ⁶ is the same or different and represents a divalent hydrocarbon group having 2 to 11 carbon atoms. m is the same or different and represents an integer of 0 to 5. R ^a , R ^b and R ^c are the same as described above. The hydrolyzable silane compound having an isocyanurate ring structure is preferably from the viewpoint of the dispersibility of the silica particles and the compatibility with the binder component (B).

Examples of the alkoxy group represented by R ^a , R ^b and R ^c include those having 1 to 8 carbon atoms, and a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an octyloxy group and the like are preferable.

Examples of the alkyl group represented by R ^a , R ^b and R ^c include those having 1 to 8 carbon atoms, and a methyl group, an ethyl group, a propyl group, a butyl group, an octyl group and the like are preferable.

Examples of the aryloxy group represented by R ^a , R ^b and R ^c include those having 6 to 18 carbon atoms, and a phenoxy group, a xylyloxy group and the like are preferable.

Examples of the aryl group represented by R ^a , R ^b and R ^c include those having 6 to 18 carbon atoms, and a phenyl group, a xylyl group and the like are preferable.

Examples of the group represented by R ^a (R ^b ) (R ^c ) Si— include a trimethoxysilyl group, a triethoxysilyl group, a triphenoxysilyl group, a methyldimethoxysilyl group, and a dimethylmethoxysilyl group. it can. Of these, a trimethoxysilyl group, a triethoxysilyl group, and the like are preferable.

  The compound represented by the formula (III) is preferably tris [(trialkoxysilyl) alkyl] isocyanurate, and examples thereof include tris (3- (trimethoxysilyl) propyl) isocyanurate.

  In the method for producing the compound represented by the formula (III), for example, silyl isocyanate is heat-treated or heated in the presence of a strongly basic catalyst such as alkali metal hydroxide or alkoxide, and cyclized to form a trimer. The organic silicon group-containing isocyanurate can be produced by a production method (Japanese Patent No. 2612996).

  A product can also be used, for example, KBM-9659 (manufactured by Shin-Etsu Chemical Co., Ltd., trade name).

  Next, the compound represented by the general formula (IV) will be described.

  The compound represented by the general formula (IV) is a compound obtained by reacting a compound represented by the following general formula (V) with a compound represented by the following general formula (VII), and / or A compound obtained by reacting a compound represented by the following general formula (V), a compound represented by the following general formula (VI) and a compound represented by the following general formula (VII) is preferably used. Can do.

［式（Ｖ）中、Ｒ^６は同一、又は異なって炭素数２〜１１の２価の炭化水素基を示す。］

[In formula (V), R ⁶ is the same or different and represents a divalent hydrocarbon group having 2 to 11 carbon atoms. ]

[In the formula (VI), Z represents a divalent saturated hydrocarbon group having 2 to 14 carbon atoms. ]

［式（ＶＩＩ）中、Ｒ^７は炭素数１〜４の２価の炭化水素基を示す。Ｒ^ａ、Ｒ^ｂ及びＲ^ｃのうち少なくとも１つは、ハロゲン原子、ヒドロキシ基、アルコキシ基又はアリールオキシ基を示し、残余は水素原子、アルキル基又はアリール基を示す。］
式（Ｖ）中のＲ^６は、炭素数２〜１１の２価の炭化水素基であれば特に限定されるものではない。具体的には例えば、エチレン基、１，２−プロピレン基、１，３−プロピレン基、１，２−ブチレン基、１，４−ブチレン基、ヘキシレン基、オクチレン基等が挙げられる。なかでも、炭素数２〜４の２価の炭化水素基であることが、得られる硬化塗膜の透明性及び耐候性の点から好ましい。

[In Formula (VII), R ⁷ represents a divalent hydrocarbon group having 1 to 4 carbon atoms. At least one of R ^a , R ^b and R ^c represents a halogen atom, a hydroxy group, an alkoxy group or an aryloxy group, and the remainder represents a hydrogen atom, an alkyl group or an aryl group. ]
R ⁶ in formula (V) is not particularly limited as long as it is a divalent hydrocarbon group having 2 to 11 carbon atoms. Specific examples include ethylene group, 1,2-propylene group, 1,3-propylene group, 1,2-butylene group, 1,4-butylene group, hexylene group, octylene group and the like. Among these, a divalent hydrocarbon group having 2 to 4 carbon atoms is preferable from the viewpoint of transparency and weather resistance of the resulting cured coating film.

  Examples of the compound represented by the general formula (V) include 1,3,5-tris- (2-hydroxyalkyl) isocyanurate, and particularly 1,3,5-tris- (2-hydroxyethyl). ) Isocyanurate can be preferably used. A commercially available product can be used as the compound represented by the general formula (V), and Tanac (trade name, manufactured by Nissei Sangyo Co., Ltd., 1,3,5-tris- (2-hydroxyethyl) isocyanate. Nurate) and the like.

  Z in formula (VI) represents a divalent saturated hydrocarbon group having 2 to 14 carbon atoms, and m is the same or different and represents an integer of 0 to 5.

  Examples of the divalent saturated hydrocarbon group having 2 to 14 carbon atoms include a methylene chain which is a linear divalent saturated hydrocarbon group having 2 to 10 carbon atoms or a part of hydrogen atoms of the methylene chain. A branched divalent saturated hydrocarbon group substituted with a lower alkyl group having 1 to 4 carbon atoms is preferred.

  Examples of the lactone compound represented by the general formula (VI) (hereinafter sometimes abbreviated as lactone compound) include γ-valerolactone, δ-valerolactone, ε-caprolactone, and α-methyl-β-propio. Lactone, β-methyl-β-propiolactone, 3-n-propyl-δ-valerolactone, 6,6-dimethyl-δ-valerolactone, β-propiolactone, γ-butyrolactone, δ-caprolactone, etc. It is done. Among these, ε-caprolactone is particularly preferable from the viewpoint of ease of handling and reactivity.

R ⁷ in the formula (VII) is not particularly limited as long as it is a divalent hydrocarbon group having 1 to 4 carbon atoms. Specific examples include ethylene group, 1,2-propylene group, 1,3-propylene group, 1,2-butylene group, 1,4-butylene group and the like.

  As the hydrolyzable silane compound represented by the formula (VII), 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane and the like can be preferably used from the viewpoint of reactivity.

  When the compound represented by the general formula (V) is reacted with the lactone compound, the reaction ratio is lactone compound with respect to 1 mol of the hydroxyl group of the compound represented by the general formula (VI) from the viewpoint of weather resistance. The molar ratio is about 0.05 to 5.0, preferably 1.0 to 3.0.

  If it is less than 0.05, the modification effect is small and the compatibility with the binder component (B) may be insufficient. On the other hand, if it exceeds 5.0, the coating film may be softened and the weather resistance may be lowered. .

  The reaction between the compound represented by the general formula (V) and the lactone compound is preferably performed in the presence of a catalyst. Use of the catalyst has an effect of promoting the ring-opening addition reaction between the lactone compound and the compound represented by the general formula (V).

  Preferred catalysts that can be used here include, for example, organic tin compounds such as n-butyltin trioctate, dibutyltin dilaurate, dimethyltin dichloride, dibutyltin dichloride, dibutyltin diacetate; stannous chloride, stannic chloride and the like. Tin halide compounds; organic zirconium compounds; organic titanium compounds such as tetra-n-butyltitanium, tetra-n-butoxytitanium, tetra-t-butoxytitanium, tetra-i-propoxytitanium, tetra-n-ethoxytitanium; Lewis acids such as boron fluoride, aluminum trichloride, zinc chloride, titanium chloride; fluoride salts such as tetrabutylammonium fluoride, cesium fluoride, potassium fluoride, rubidium fluoride, etc., but are not limited thereto. It is not something. These catalysts may be used alone or in combination of two or more.

  The compounding amount of the catalyst used is about 0.01 to 10% by mass, preferably about 0.02 to 4.0% by mass, with respect to the total amount of the compound represented by the general formula (V) and the lactone compound.

  The ring-opening addition reaction can be suitably carried out in the temperature range of usually about 80 to 200 ° C, preferably about 100 to 180 ° C, in the absence of a solvent or in the presence of a solvent inert to the reaction. The reaction time is usually about 1 to 20 hours.

  Examples of the inert solvent include aromatic hydrocarbons such as toluene, xylene, hexane, and heptane, aliphatic hydrocarbons, esters such as ethyl acetate, butyl acetate, methyl benzoate, and methyl propionate. Examples include ether solvents such as tetrahydrofuran, dioxane and dimethoxyethane, ketone solvents such as acetone and methyl ethyl ketone, and halogenated hydrocarbon solvents such as dichloromethane and chloroform. These may be used alone or in combination of two or more. May be.

  It is undesirable to use a large amount of a solvent active in the reaction, for example, a solvent containing a hydroxyl group, because the modification rate of the lactone is lowered.

  As a reaction method, for example, a compound represented by the general formula (V) and a lactone compound represented by the general formula (VI) may be mixed and heated, or a lactone compound may be added. The catalyst may be put in the compound represented by the general formula (V) in advance or may be mixed with the lactone compound and dropped together.

  As described above, the compound represented by the following general formula (VIII) can be produced by reacting the general formula (V) with the lactone compound represented by the following general formula (VI).

［式（ＶＩＩＩ）中、Ｒ^６、ｍ、Ｒ^ａ、Ｒ^ｂ、及びＲ^ｃは前記と同じである。］
前記一般式（ＩＶ）で表される化合物は、上記のようにして得られた前記一般式（ＶＩＩＩ）で表される化合物及び／又は一般式（Ｖ）で表される化合物と、前記一般式（ＶＩＩ）で表される化合物とを反応させることにより得ることができる。

[In the formula (VIII), R ⁶ , m, R ^a , R ^b and R ^c are the same as above. ]
The compound represented by the general formula (IV) includes the compound represented by the general formula (VIII) and / or the compound represented by the general formula (V) obtained as described above, and the general formula It can be obtained by reacting with a compound represented by (VII).

  The mixing ratio of the compound represented by the general formula (VIII) and / or the compound represented by the general formula (V) with the compound represented by the general formula (VII) is particularly Although not limited thereto, the compound represented by the general formula (VII) is usually used with respect to 1 mol of the hydroxyl group of the compound represented by the general formula (VIII) and / or the compound represented by the general formula (V). The reaction is carried out so that the isocyanate group of the hydrolyzable silane compound represented by the formula is equal to or less than equimolar and 1 equivalent or more of the hydrolyzable silyl group is introduced.

  As a specific blending ratio, the compound represented by the general formula (VIII) and / or the compound represented by the general formula (V) from the viewpoint of dispersibility of the silica particles (A) whose surfaces are modified. The isocyanate group of the hydrolyzable silane compound represented by the general formula (VII) is 0.05 to 1.0, preferably 0.1 to 0.4 mol, based on 1 mol of the hydroxyl group of It is preferable that

  This reaction can be performed according to a conventional method in which an isocyanate group and a hydroxyl group are reacted. The reaction temperature is, for example, 0 to 200 ° C, preferably 20 to 200 ° C, more preferably 20 ° C to 120 ° C. This reaction can be carried out even under pressure (or reduced pressure), but a pressure range of 0.02 to 0.2 MPa, particularly 0.08 to 0.15 MPa is preferred. The reaction is usually completed in about 2 to 10 hours.

  In the reaction, a solvent may be appropriately used. As the solvent, those exemplified as the inert solvent can be preferably used.

  In the reaction, a urethanization catalyst may be used. Examples of the urethane curing catalyst include tin octylate, dibutyltin diacetate, dibutyltin di (2-ethylhexanoate), dibutyltin dilaurate, dioctyltin diacetate, dioctyltin di (2-ethylhexanoate), Dibutyltin oxide, dioctyltin oxide, dibutyltin fatty acid salt, lead 2-ethylhexanoate, zinc octylate, zinc naphthenate, fatty acid zinc compound, cobalt naphthenate, calcium octylate, copper naphthenate, tetra (2-ethylhexyl) Organometallic compounds such as titanate; tertiary amines and the like can be mentioned, and these can be used alone or in combination of two or more.

  And the silica particle (A) by which the surface was modified with the compound represented by the said general formula (III) and / or the hydrolysable silane compound represented by the compound represented by the said general formula (IV) is manufactured. In such a case, the compound represented by the general formula (V), the compound represented by the general formula (VI), the compound represented by the general formula (VIII), or the like is included in the raw material for the production. There is no particular problem.

Hydrolyzable silane compound (a-ii)
The hydrolyzable silane compound (a-ii) has the following general formula (II)

［式（ＩＩ）中、Ｒ^４はである炭素数１〜１８の１価の炭化水素基を示す。Ｒ^ａ、Ｒ^ｂ及びＲ^ｃのうち少なくとも１つは、ハロゲン原子、ヒドロキシ基、アルコキシ基又はアリールオキシ基を示し、残余は水素原子、アルキル基又はアリール基を示す。］で表されるイソシアヌレート環構造を有さない加水分解性シラン化合物である。

[In Formula (II), R ⁴ represents a monovalent hydrocarbon group having 1 to 18 carbon atoms. At least one of R ^a , R ^b and R ^c represents a halogen atom, a hydroxy group, an alkoxy group or an aryloxy group, and the remainder represents a hydrogen atom, an alkyl group or an aryl group. ] The hydrolysable silane compound which does not have the isocyanurate ring structure represented by this.

R ⁴ is not particularly limited as long as it is a divalent hydrocarbon group having 1 to 18 carbon atoms. Specifically, in terms of availability and price, for example, selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, cyclohexylmethyl, hexyl, octyl, decyl, and phenyl groups Among them, one or more selected from the above are preferable, and among them, a methyl group, an ethyl group, a propyl group, a cyclohexylmethyl group, an octyl group, a decyl group and a phenyl group are preferable.

Examples of the hydrolyzable group represented by R ^a , R ^b and R ^c include a halogen atom, a hydrogen atom, a hydroxy group, an alkoxy group or an aryloxy group, an alkyl group, an aryl group, and the like. It is preferable that it is 1 or more types chosen from a group and an oxycarbonyl group, Among these, an alkoxy group is more preferable at the point of availability and a price, and a C3-C3 or less alkoxy group is further more preferable.

Examples of the group represented by R ^a (R ^b ) (R ^c ) Si— include a trimethoxysilyl group, a triethoxysilyl group, a triphenoxysilyl group, a methyldimethoxysilyl group, and a dimethylmethoxysilyl group. it can. Of these groups, a trimethoxysilyl group, a triethoxysilyl group, and the like are preferable.

  Specific examples of the hydrolyzable silane compound (a-ii) include methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, isopropyltrimethoxysilane, butyltrimethoxysilane, cyclohexyltrimethoxysilane, Examples include hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, and phenyltrimethoxysilane. Moreover, the compound (for example, methyl triethoxysilane etc.) which substituted the methoxy group in these illustrated compounds by the ethoxy group is also mentioned. Among them, from the viewpoint of dispersibility, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, cyclohexylmethyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane and / or methoxy group were substituted with ethoxy groups. Compounds are preferred.

  These hydrolyzable silane compounds (a-ii) may be used alone or in combination of two or more.

<< Method for Producing Silica Particles (A) Modified on the Surface >>
The surface-modified silica particles (A) can be obtained by reacting the silica fine particles (s) with the hydrolyzable silane compound (a). The hydrolyzable silane compound (a) includes a hydrolyzable silane compound (ai) and a hydrolyzable silane compound (a-ii). [Hereinafter, the hydrolyzable silane compound (a) may be collectively referred to as “hydrolyzable silane”. The method for reacting the silica fine particles (s) with the hydrolyzable silane is not particularly limited.

For example,
[I] A method in which silica fine particles and hydrolyzable silane are mixed in the presence of an organic solvent containing water to perform hydrolytic condensation,
[Ii] A method of condensing a hydrolyzate of hydrolyzable silane with silica fine particles after hydrolyzing the hydrolyzable silane in the presence of an organic solvent containing water,
[Iii] A method in which silica fine particles (s) and a hydrolyzable silane are mixed in the presence of water, an organic solvent and other components, and hydrolytic condensation is performed at one time.

  Here, the water used in these production methods may be water contained in the raw material, for example, water that is a dispersion medium of colloidal silica fine particles.

  The method for producing the silica particles (A) whose surfaces are modified will be described more specifically. The silica particles whose surface is modified include, for example, colloidal silica fine particles which are silica fine particles (s), hydrolyzable silane, optionally lower alcohol, dispersion medium in the colloidal silica fine particles, and lower alcohol (hydrolyzable). Including lower alcohol produced by hydrolyzing silane) under normal pressure or reduced pressure together with a solvent having a boiling point higher than that of lower alcohol, substituting the dispersion medium with the solvent, and then dehydrating under heating It can be produced by a condensation reaction.

  In this production method, the hydrolyzable silane is mixed with a colloidal silica fine particle (s), a hydrolyzable silane, and optionally a mixture of a lower alcohol with a conventional method such as stirring at room temperature or under heating. Hydrolyze. In this case, a hydrolysis catalyst may be used. Subsequently, the dispersion medium in the colloidal silica fine particles (s) and the lower alcohol were azeotropically distilled together with a solvent having a boiling point higher than that of the lower alcohol under normal pressure or reduced pressure, and the dispersion medium was replaced with the solvent. The reaction is carried out with stirring for 0.5 to 10 hours at a temperature of ˜150 ° C., preferably 80 to 130 ° C., usually while maintaining the solid content concentration in the range of 5 to 50 mass%. After the reaction, it is preferable to azeotropically distill water and lower alcohol generated by condensation reaction or hydrolysis together with a solvent having a boiling point higher than that of the lower alcohol.

  As the solvent used in the above reaction, for example, those exemplified as the inert solvent can be preferably used.

  Various conventionally known catalysts can be used as the hydrolysis catalyst. Specific examples include, for example, organic acids such as acetic acid, butyric acid, maleic acid and citric acid, inorganic acids such as hydrochloric acid, nitric acid, phosphoric acid and sulfuric acid, basic compounds such as triethylamine, and the urethanization catalyst. Fluorine-containing compounds such as organometallic compounds such as tetrabutyl titanate and dibutyltin dilaurate, and fluoride salts such as tetrabutylammonium fluoride, cesium fluoride, potassium fluoride, and rubidium fluoride can be given.

  The said hydrolysis catalyst may be used independently, or may use multiple types together. The amount of the catalyst used is preferably in the range of 0.0001 to 1 part by mass based on 100 parts by mass of silica fine particles (s). Among these catalysts, the fluorine-containing compound is excellent in the function of accelerating the condensation of silanol groups rich in reaction activity, and thus the surface-modified silica particles (A) have good storage stability in the coating composition. This is preferable.

  The solid content concentration during the reaction is preferably in the range of 5 to 50% by mass. When the solid content concentration is less than 5% by mass, that is, when the solvent exceeds 95% by mass, the reaction between the silica fine particles (s) and the hydrolyzable silane becomes insufficient, and the resulting cured coating film may be inferior in transparency. . On the other hand, if the solid content concentration exceeds 50% by mass, the product may be gelled.

  By these production methods, the silicon atom on the surface of the silica fine particle and the silicon atom of the hydrolyzable silane are bonded via an oxygen atom, so that the surface where the silica fine particle (s) and the hydrolyzable silane are chemically bonded is obtained. Modified silica particles (A) are obtained.

  The solid content ratio (solid content ratio) between the hydrolyzable silane compound (ai) and the hydrolyzable silane compound (a-ii) when the surface-modified silica particles (A) are obtained is dispersibility. From the viewpoints of finish, scratch resistance, hydrolyzable silane compound (ai) / hydrolyzable silane compound (a-ii) = 0.05 to 5.0 (mass ratio) is preferable. In particular, the range of 0.5 to 1.5 is more preferable.

  The solid content blending amount of the hydrolyzable silane compound (a) is preferably 1 to 55 parts by mass based on 100 parts by mass of silica fine particles (s) from the viewpoint of dispersibility, finish and scratch resistance. 15-45 mass parts is especially preferable.

  This blending amount varies depending on the average particle size of the silica particles. For example, when the average particle size is 10 to 20 nm, the solid blending amount of the hydrolyzable silane compound (a) is 100 parts by mass of the silica fine particles. Preferably it is 10-50 mass parts, More preferably, it is 15-45 mass parts.

  Moreover, when an average particle diameter is 20-30 nm, Preferably solid content compounding quantity of a hydrolysable silane compound (a) is 10-40 mass parts with respect to 100 mass parts of silica fine particles, More preferably, 15 -35 parts by mass.

  Moreover, when an average particle diameter is 40-50 nm, Preferably solid content of hydrolysable silane compound (a) is 1-30 mass parts with respect to 100 mass parts of silica fine particles, More preferably, 5 -15 parts by mass.

  These silica particles (A) may be used alone or in combination of two or more.

  The solid content of the silica particles (A) whose surfaces are modified in the coating composition of the present invention is preferably described later, from the viewpoint of improvement in scratch resistance, coating film hardness and transparency of the resulting coating film. They are 1-200 mass% and 1-40 mass% with respect to the total resin solid content of a binder component (B), More preferably, it is 2-30 mass%.

≪Binder component (B) ≫
The coating composition of the present invention contains a binder component (B).

  The binder component is a synthetic resin that can form a main cured coating film, and examples of the synthetic resin that is a binder component include non-crosslinked resins and crosslinked resins.

  The synthetic resin capable of forming a main cured film refers to a resin that occupies 10% by mass or more and 100% by mass or less among the components for forming the cured film excluding silica particles (A) whose surface is modified.

  Examples of the non-crosslinked resin include polyethylene, nylon resin, vinyl chloride resin, and the like.

  As the cross-linked resin, a known thermosetting resin that reacts and cures by heating can be used. Among these, from the viewpoints of scratch resistance, weather resistance, acid resistance, coating film productivity, and the like, the hydroxyl group-containing resin (Bi) and the crosslinking agent (B-ii) can be preferably used.

<Hydroxyl-containing resin (Bi)>
The hydroxyl group-containing resin (B-i) is not particularly limited as long as it contains a hydroxyl group, and a known thermosetting resin can be used.

  For example, alkyd resin, polyester resin, acrylic resin, cellulose resin and the like can be mentioned. From the viewpoint of weather resistance and scratch resistance of the coating film, a hydroxyl group-containing acrylic resin (Bi-1) is preferable.

  The hydroxyl group-containing acrylic resin (Bi-1) is produced by copolymerizing a hydroxyl group-containing polymerizable unsaturated monomer and other polymerizable unsaturated monomers copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer. can do.

  The hydroxyl group-containing polymerizable unsaturated monomer is a compound having at least one hydroxyl group and one polymerizable unsaturated group in one molecule.

  As the hydroxyl group-containing polymerizable unsaturated monomer, specifically, a monoesterified product of acrylic acid or methacrylic acid and a dihydric alcohol having 2 to 10 carbon atoms is suitable. For example, 2-hydroxyethyl (meth) Acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, caprolactone-modified hydroxyl group Examples thereof include (meth) acrylate, 4-methylolcyclohexyl (meth) acrylate, and the like. Examples of commercially available products of caprolactone-modified hydroxyl group-containing (meth) acrylates include “Placcel FM” (trade name, manufactured by Daicel Chemical Industries), and the like, and examples of commercially available 4-methylolcyclohexyl acrylate include “CHDMMA”. (Trade name, manufactured by Nippon Kasei Co., Ltd.).

  As the hydroxyl group-containing polymerizable unsaturated monomer, from the viewpoint of scratch resistance of the coating film to be formed, in particular, a polymerizable unsaturated monomer having a hydroxyl group-containing hydrocarbon group having 4 to 20 carbon atoms, specifically, It is preferable to use 4-hydroxybutyl (meth) acrylate, 4-methylol cyclohexyl acrylate, or the like.

  The hydroxyl group based on the hydroxyl group-containing polymerizable unsaturated monomer functions as a crosslinkable functional group of the resulting copolymer resin.

  The other copolymerizable polymerizable unsaturated monomer is a compound having one or more polymerizable unsaturated groups in one molecule other than the hydroxyl group-containing polymerizable unsaturated monomer, and specific examples thereof are as follows. Listed in (1) to (13).

(1) Aromatic polymerizable unsaturated monomer: For example, styrene, α-methylstyrene, vinyltoluene and the like.

  (2) C3-C20 alicyclic hydrocarbon group-containing polymerizable unsaturated monomer: for example, isobornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, adamantyl (meth) acrylate, 3,5- Bridged alicyclic hydrocarbon group-containing polymerizable unsaturated monomer having 10 to 20 carbon atoms such as dimethyladamantyl (meth) acrylate, 3-tetracyclododecyl (meth) acrylate, cyclohexyl (meth) acrylate, 4-methylcyclohexyl Methyl (meth) acrylate, 4-ethylcyclohexylmethyl (meth) acrylate, 4-methoxycyclohexylmethyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, cyclooctyl (meth) acrylate, cyclododecyl (meth) acrylate, tet Tetrahydrofurfuryl (meth) polymerizable unsaturated monomer having an alicyclic hydrocarbon group having 3 to 12 carbon atoms in the acrylate.

  (3) Polymerizable unsaturated monomer having a branched hydrocarbon structure having 8 or more carbon atoms: for example, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isomyristyl (meth) acrylate, isostearyl ( And (meth) acrylate. As a commercial product, “isostearyl acrylate” (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd.).

  (4) C1-C7 linear or branched alkyl ester of (meth) acrylic acid: methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl ( (Meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate and the like.

  (5) C8-22 linear alkyl ester of (meth) acrylic acid: for example, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like.

  (6) Epoxy group-containing polymerizable unsaturated: for example, glycidyl (meth) acrylate.

  (7) Nitrogen-containing polymerizable unsaturated monomer: for example, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, vinylpyridine, vinylimidazole and the like.

  (8) Other vinyl compounds: for example, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride, divinyl ether, versatic acid vinyl ester “Veoba 9”, “Veoba 10” (trade name, Japan Epoxy Resin Co., Ltd.) Made) etc.

  (11) Unsaturated group-containing nitrile compound: For example, (meth) acrylonitrile and the like.

  (12) Acidic functional group-containing polymerizable unsaturated monomer: for example, (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride and other carboxyl group-containing unsaturated monomers; vinyl sulfonic acid, sulfoethyl (meth) Sulfonic acid group-containing unsaturated monomers such as acrylate; 2- (meth) acryloyloxyethyl acid phosphate, 2- (meth) acryloyloxypropyl acid phosphate, 2- (meth) acryloyloxy-3-chloropropyl acid phosphate, 2- Acid phosphate ester unsaturated monomers such as (meth) acryloyloxyethylphenyl phosphoric acid.

  (13) Alkoxysilyl group-containing polymerizable unsaturated monomer: for example, vinyltrimethoxysilane, vinyltriethoxysilane, acryloxyethyltrimethoxysilane, methacryloxyethyltrimethoxysilane, acryloxypropyltrimethoxysilane, methacryloxypropyltri Examples include methoxysilane, acryloxypropyltriethoxysilane, methacryloxypropyltriethoxysilane, and vinyltris (β-methoxyethoxy) silane.

  The said other copolymerizable polymerizable unsaturated monomer can be used individually or in combination of 2 or more types.

A hydroxyl group-containing acrylic resin (B-i-1) can be obtained by copolymerizing the polymerizable unsaturated monomer mixture comprising the hydroxyl group-containing polymerizable unsaturated monomer and the other polymerizable unsaturated monomer.

  The proportion of the hydroxyl group-containing polymerizable unsaturated monomer used is 24 to 50% by mass, preferably 30 to 45% by mass, based on the total mass of the copolymerization monomer component, from the viewpoint of scratch resistance and finish. Is appropriate.

  As other polymerizable unsaturated monomer, it is desirable to use the monomer (1) from the viewpoints of finish (particularly gloss), water resistance and weather resistance, and the use ratio is based on the total mass of the copolymerization monomer components. Thus, it is appropriate to be about 3 to 40% by mass, preferably about 5 to 30% by mass.

  Moreover, it is desirable to use the monomer (2) as the other polymerizable unsaturated monomer from the viewpoint of finish and water resistance, and the proportion of use is 3 to 40 based on the total mass of the copolymerization monomer component. It is appropriate that the amount is about 5% by mass, preferably about 5 to 30% by mass.

  In addition, it is desirable to use the monomer (3) as the other polymerizable unsaturated monomer from the viewpoint of the wettability to the object to be coated and the finish, and the use ratio is based on the total mass of the copolymerization monomer component. Thus, it is appropriate to be about 3 to 40% by mass, preferably about 8 to 35% by mass.

  From the viewpoint of obtaining a resin that is extremely excellent in both acid resistance and scratch resistance of the coating film based on the total mass of the copolymerization monomer component, the monomer (1), monomer (2), and monomer (3) The total mass of is suitably in the range of about 35 to 70% by mass, preferably about 40 to 65% by mass, based on the total mass of the copolymerizable monomer components.

    Among other polymerizable unsaturated monomers, acidic functional group-containing polymerizable unsaturated monomers such as carboxyl group-containing unsaturated monomers, sulfonic acid group-containing unsaturated monomers, and acidic phosphate ester-based unsaturated monomers are obtained hydroxyl groups. It can act as an internal catalyst when the contained resin undergoes a crosslinking reaction with the polyisocyanate compound, and the amount used is within the range of about 0.1 to 5% by mass based on the total amount of the monomer mixture constituting the resin. Is preferable, and can be used within a range of about 0.5 to 3% by mass.

  In the present specification, “(meth) acrylate” means “acrylate or methacrylate”. “(Meth) acrylic acid” means “acrylic acid or methacrylic acid”. “(Meth) acryloyl” means “acryloyl or methacryloyl”. “(Meth) acrylamide” means “acrylamide or methacrylamide”.

  The copolymerization method for copolymerizing the monomer mixture to obtain the hydroxyl group-containing acrylic resin (Bi-1) is not particularly limited, and a known copolymerization method can be used. In particular, it is preferable to use a solution polymerization method in which polymerization is performed in an organic solvent in the presence of a polymerization initiator.

  Examples of the organic solvent used in the solution polymerization method include aromatic solvents such as toluene, xylene, and high-boiling aromatic hydrocarbons; ethyl acetate, 3-methoxybutyl acetate, ethylene glycol ethyl ether acetate, propylene glycol Ester solvents such as methyl ether acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, etc. Glycol ether solvents: propyl propionate, butyl propionate, ethoxyethyl propionate, etc.Examples of commercially available high-boiling aromatic hydrocarbons include “Swazole 1000” (trade name, manufactured by Cosmo Oil Co., Ltd., high-boiling petroleum solvent).

  These organic solvents can be used alone or in combination of two or more. In particular, as the organic solvent, since the hydroxyl group-containing acrylic resin (Bi-1) has a high hydroxyl value, it is preferable to use an ester solvent or a ketone solvent having a high boiling point from the viewpoint of the solubility of the resin. Furthermore, a high boiling point aromatic solvent can be used in combination.

  Examples of the polymerization initiator that can be used in the copolymerization of the hydroxyl group-containing acrylic resin (Bi-1) include 2,2′-azobisisobutyronitrile, benzoyl peroxide, and 2,2-di (t-amyl). Peroxy) butane, di-t-butyl peroxide, di-t-amyl peroxide, t-butyl peroctoate, 2,2′-azobis (2-methylbutyronitrile) and other known radical polymerization initiators Can be mentioned.

  The hydroxyl group-containing acrylic resin (Bi-1) may be composed of one kind of copolymer, but may be composed of two or more kinds of copolymers.

  The hydroxyl value of the hydroxyl group-containing acrylic resin (Bi-1) is preferably 10 to 200 mgKOH / g, more preferably 80 to 200 mgKOH / g, and still more preferably 120 from the viewpoint of achieving both scratch resistance and water resistance. Within the range of ~ 200 mg KOH / g.

  The weight average molecular weight of the hydroxyl group-containing acrylic resin (Bi-1) is preferably in the range of 5,000 to 30,000, more preferably 5,000 to 20 from the viewpoints of acid resistance and finish. , More preferably in the range of 10,000 to 20,000.

  In addition, in this specification, a weight average molecular weight is the value computed on the basis of the molecular weight of standard polystyrene from the chromatogram measured by the gel permeation chromatograph. As the gel permeation chromatograph, “HLC8120GPC” (manufactured by Tosoh Corporation) was used. As the columns, four columns of “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL”, “TSKgel G-2000HXL” (both manufactured by Tosoh Corporation, trade name) were used, Mobile phase: Tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 cc / min, detector: RI

  The glass transition temperature of the hydroxyl group-containing acrylic resin (Bi-1) is preferably in the range of −30 ° C. to 30 ° C., particularly in the range of −20 ° C. to 20 ° C., from the viewpoints of coating film hardness and finish.

  The glass transition temperature (° C.) was calculated by the following formula.

1 / Tg (K) = (W1 / T1) + (W2 / T2) +
Tg (° C.) = Tg (K) -273
In each formula, W1, W2,... Are the respective mass fractions of the monomers used for the copolymerization,
T1, T2,... Represent the homopolymer Tg (K) of each monomer.
T1, T2,... Are values according to Polymer Handbook (4th Edition, edited by J. Brandup, E. H. Immergut).
In addition, when using the monomer which is not described in the said literature (data) as a copolymerization monomer component, the homopolymer of this monomer was synthesize | combined so that a weight average molecular weight might be about 50,000, and the glass transition temperature was set. Use the value measured by differential scanning thermal analysis.

<Crosslinking agent (B-ii)>
As the crosslinking agent (B-ii) to be combined with the hydroxyl group-containing resin, polyisocyanate compounds (including blocked ones), amino resins such as melamine resins, guanamine resins and urea resins can be used. Polyisocyanate compound (B-ii-1) and / or melamine resin (B-ii-2) are preferable from the viewpoint of obtaining a coating film superior in weather resistance, scratch resistance, coating film hardness, adhesion and the like.

  The polyisocyanate compound (B-ii-1) is a compound having two or more isocyanate groups in one molecule.

  Examples of the polyisocyanate compound (B-ii-1) include aliphatic diisocyanates such as hexamethylene diisocyanate or trimethylhexamethylene diisocyanate; cyclic aliphatic diisocyanates such as hydrogenated xylylene diisocyanate or isophorone diisocyanate; Organic diisocyanates such as aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate per se, or adducts of these organic diisocyanates with polyhydric alcohols, low molecular weight polyester resins or water, or organic diisocyanates as described above Competitors' cyclized polymers, and isocyanate / biuret products are listed, but these polyisocyanate compounds are blocked. It can also be used those blocked with agents. When using a blocked isocyanate compound, it is preferable to use a dissociation catalyst in combination.

  Examples of typical commercially available isocyanate compounds include Vernock D-750, -800, DN-950, -970 or 15-455 (above, trade name, manufactured by DIC Corporation), Sumidur N3300, or N3390. (Above, trade name, manufactured by Sumitomo Bayer Urethane Co., Ltd.), Duranate 24A-100, TPA-100, TLA-100, P301-75E "(above, trade name, manufactured by Asahi Kasei Corporation) and the like.

  Examples of the polyisocyanate compound having a blocked isocyanate group include those obtained by blocking the above-mentioned polyisocyanate compound having a free isocyanate group with a known blocking agent such as oxime, phenol, alcohol, lactam, malonic ester, mercaptan, and the like. It is done. Examples of these typical commercially available products include Barnock D-550 (trade name, manufactured by DIC Corporation) or Duranate SBN-70 (trade name, manufactured by Asahi Kasei Corporation).

  As the melamine resin (B-ii-2), for example, a melamine resin obtained by etherifying a methylol group of methylolated melamine with a monohydric alcohol having 1 to 8 carbon atoms can be preferably used. The etherified melamine resin may be one in which all methylol groups of the methylolated melamine are etherified, or may be partially etherified to leave a methylol group or imino group.

  Specific examples of the etherified melamine resin include alkyl etherified melamines such as methyl etherified melamine, ethyl etherified melamine, and butyl etherified melamine. Only one type of etherified melamine resin may be used, or two or more types may be used in combination.

  Examples of commercially available melamine resins include butylated melamine resins (Mitsui Chemicals, Inc .; Uban 20SE-60, Uban 225, DIC Corporation; Super Becamine G840, Super Becamine G821, etc.), methylated melamine, and the like. Resin (Nippon Cytec Industries, Inc .; Cymel 303, Sumitomo Chemical Co., Ltd .; Sumimar M-100, Sumimar M-40S, etc.), methyl etherified melamine resin (Nippon Cytec Industries, Ltd .; Cymel 303, Cymel 325, Cymel 327, Cymel 350, Cymel 370, Sumitomo Chemical Sumimar M55, etc.), methylated, butylated mixed etherified melamine resin (Nippon Cytec Industries, Ltd .; Cymel 253, Cymel 202, Cymel 23) , Cymel 254, Cymel 272, Cymel 1130, Sumitomo Chemical Co., Ltd.; Sumimal M66B, etc.), can be used methylation, isobutylated mixed etherified melamine resin (Nihon Cytec Industries Cymel XV805 etc.) melamine resins, such as.

  The blending ratio of the crosslinking agent (B-ii) may be appropriately blended so that the coating film is cured and has sufficient performance, but from the viewpoint of curability of the resulting coating film, the ratio of the hydroxyl group-containing resin / crosslinking agent. Is preferably in the range of 80/20 to 50/50 by mass ratio.

  When a polyisocyanate compound is used for the crosslinking agent (B-ii), the blending ratio is equivalent ratio (NCO / OH) between the isocyanate group of the polyisocyanate compound and the hydroxyl group of the hydroxyl group-containing resin in the coating composition of the present invention. However, the range of usually 0.5 to 2.0, particularly 0.7 to 1.5 is preferable.

<Other ingredients>
The coating composition of the present invention further comprises a curing catalyst, a pigment, an ultraviolet absorber (for example, a benzotriazole-based absorber, a triazine-based absorber, a salicylic acid derivative-based absorber, a benzophenone-based absorber, etc.), a light stabilizer (for example, Hindered piperidines, etc.), thickeners, antifoaming agents, plasticizers, organic solvents, surface conditioners, anti-settling agents and other usual paint additives, etc., either alone or in combination of two or more. Can do.

Examples of the curing catalyst include tin octylate, dibutyltin di (2-ethylhexanoate), dioctyltin di (2-ethylhexanoate), dioctyltin diacetate, dibutyltin dilaurate, dibutyltin oxide, and dioctyl. Examples thereof include organometallic catalysts such as tin oxide and lead 2-ethylhexanoate, and tertiary amines. These can be used alone or in combination of two or more.

  When the coating composition of this invention contains a curing catalyst, the compounding quantity of a curing catalyst exists in the range of 0.05-10 mass parts on the basis of 100 mass parts of resin solid content of a binder component (B). It is preferably within a range of 0.1 to 5 parts by mass, and more preferably within a range of 0.2 to 3 parts by mass.

  When the coating composition of this invention contains a ultraviolet absorber, the compounding quantity of a ultraviolet absorber is in the range of 0.1-10 mass parts on the basis of 100 mass parts of resin solid content of a binder component (B). It is preferable that it is in the range of 0.2 to 5 parts by mass, and more preferably in the range of 0.3 to 2 parts by mass.

  When the coating composition of this invention contains a light stabilizer, the compounding quantity of a light stabilizer is in the range of 0.1-10 mass parts on the basis of 100 mass parts of solid content of a binder component (B). It is preferable that it is within a range of 0.2 to 5 parts by mass, and more preferably within a range of 0.3 to 2 parts by mass.

  The coating composition of the present invention may be a one-component paint or a multi-component paint such as a two-component paint. In the coating composition of the present invention, when a non-blocked polyisocyanate compound is used as the crosslinking agent (B-ii) of the binder component (B), from the viewpoint of storage stability, a hydroxyl group-containing resin (B It is preferable to use a two-component paint comprising a main agent containing -i) and a curing agent containing a cross-linking agent (B-ii) and mixing both of them immediately before use.

<Adjustment of coating composition>
The form of the coating composition of the present invention is not particularly limited, but an organic solvent solution type or a non-aqueous dispersion type is preferable.

  Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as ethyl acetate, butyl acetate, methyl benzoate, ethyl ethoxypropionate, ethyl propionate, and methyl propionate; tetrahydrofuran, dioxane, Ethers such as dimethoxyethane; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and 3-methoxybutyl acetate; aromatic hydrocarbons and aliphatic hydrocarbons Etc.

  These can be used in appropriate combination depending on the purpose such as adjustment of viscosity and adjustment of coating property.

  The solid content of the coating composition of the present invention is not particularly limited. For example, in terms of smoothness of the cured coating film and shortening of the drying time, the organic solvent or the like so that the viscosity is within a range of about 15 to 60 seconds / Ford Cup # 4/20 ° C. It is preferable to adjust appropriately using these solvents.

  In the present specification, the solid content means a residue excluding a volatile component, and the residue may be solid or liquid at room temperature. The solid content mass can be calculated by taking the ratio of the amount of the remaining substance when dried to the mass before drying as the solid content rate, and multiplying the solid content rate by the sample mass before drying.

<Coating method>
The article to be coated to which the coating composition of the present invention is applied is not particularly limited. For example, cold rolled steel plates, galvanized steel plates, zinc alloy plated steel plates, stainless steel plates, tin plated steel plates and other metal substrates, aluminum plates, aluminum alloy plates and other metal substrates, and various plastic materials. Moreover, the vehicle body of various vehicles, such as a motor vehicle, a two-wheeled vehicle, and a container formed of these, may be sufficient.

  Moreover, as a to-be-coated object, surface treatments, such as a phosphate process, a chromate process, complex oxide process, may be given to the metal surface of the said metal base material or a vehicle body. Further, as the object to be coated, an undercoat film such as various electrodeposition paints may be formed on the metal substrate or the vehicle body, and the undercoat film and the intermediate coat film are formed. It may be an undercoating film, an intermediate coating film, and a base coating film, and an undercoating film, an intermediate coating film, a base coating film, and a clear coating film are formed. It may be.

  The coating method of the coating composition of the present invention is not particularly limited, and examples thereof include coating methods such as air spray coating, airless spray coating, rotary atomization coating, and curtain coat coating. Can be formed. In these coating methods, electrostatic application may be performed as necessary. Of these, air spray coating or rotary atomization coating is particularly preferred.

  In general, the coating amount of the coating composition of the present invention is preferably set to an amount of about 10 to 50 μm as a cured film thickness.

  When air spray coating, airless spray coating, and rotary atomization coating are performed, the viscosity of the coating is adjusted to a viscosity range suitable for the coating, usually Ford Cup No. In a 4-viscosity meter, it is preferable to adjust appropriately using a solvent such as an organic solvent so that the viscosity is within a range of about 15 to 60 seconds at 20 ° C.

  Curing of the wet coating film obtained by coating the coating composition of the present invention on the object to be coated is performed by heating, and the heating can be performed by a known heating means, for example, a hot air furnace, an electric furnace, an infrared ray A drying furnace such as an induction heating furnace can be used. The heating temperature is in the range of 60 to 180 ° C, preferably 90 to 150 ° C. The heating time is not particularly limited, but is preferably within the range of 10 to 60 minutes, preferably 15 to 30 minutes.

  Since the coating composition of the present invention can provide a cured coating film that is excellent in all of scratch resistance, acid resistance, stain resistance, and coating film appearance, it can be suitably used as a top-coat top clear coat coating composition. it can. This paint can be particularly suitably used as an automobile paint.

<Multilayer coating film forming method>
As a method for forming a multilayer coating film in which the coating composition of the present invention is applied as a top-top clear coat paint, at least one colored base coat paint and at least one clear coat paint are sequentially applied to an object to be coated. And a method for forming a multilayer coating film comprising applying the coating composition of the present invention as an uppermost clear coating composition.

  Specifically, for example, a solvent-type or water-based base coat paint is applied on an object to which electrodeposition coating and / or intermediate coating has been applied, and the coating film is not cured, as needed. In order to promote the volatilization of the solvent in the base coat paint, for example, preheating was performed at 40 to 90 ° C. for about 3 to 30 minutes, and this paint was applied as a clear coat paint on the uncured base coat film. Thereafter, there can be mentioned a method for forming a multi-layer coating film of a 2-coat 1-bake method in which the base coat and the clear coat are cured together.

  Moreover, this paint can also be suitably used as a top clear coat paint in the top coat of the 3-coat 2-bake method or the 3-coat 1-bake method.

  As the base coat paint used in the above, a conventionally known normal thermosetting base coat paint can be used. Specifically, for example, a base resin such as an acrylic resin, a polyester resin, an alkyd resin, a urethane resin type, or the like. In addition, a coating material obtained by appropriately combining a curing agent such as an amino resin, a polyisocyanate compound, or a block polyisocyanate compound with a reactive functional group contained in the base resin can be used.

  As the base coat paint, for example, an aqueous paint, an organic solvent-based paint, and a powder paint can be used.

  In the multilayer coating film forming method, when two or more clear coats are applied, a conventionally known normal thermosetting clear coat paint can be used as the clear coat paint other than the uppermost layer.

  The cured coating film obtained by applying the coating composition of the present invention is excellent in scratch resistance and coating film appearance. The surface was modified by a hydrolyzable silane compound (a) having a hydrolyzable silane compound (ai) having an isocyanurate ring structure and a hydrolyzable silane compound not having an isocyanurate ring structure. By using the silica particles (A), the compatibility between the binder component (B) and the silica particles is improved, so that the silica particles are uniformly dispersed, and the cured coating film impairs finishing properties such as transparency and glossiness. Without having an excellent scratch resistance.

  Hereinafter, the present invention will be described in more detail with reference to examples. “Part” and “%” indicate “part by mass” and “% by mass” unless otherwise specified.

  The solid content (%) was obtained by weighing 2 g of a sample in a tin plate and drying it at 130 ° C. for 30 minutes. The ratio of the amount of the remaining material to the mass before drying was defined as the solid content. Calculated by multiplying the sample mass.

  The isocyanate value was measured by adding 10 ml of a 0.1 mol / L dibutylamine solution to 1 g of the sample and reacting, and titrating the remaining dibutylamine with an aqueous hydrochloric acid solution using bromophenol blue as a titration indicator.

(Production Example 1) Hydrolyzable silane compound No. 1 Production of 1 Into a four-necked flask equipped with a reflux condenser, a thermometer, an air introduction tube and a stirrer, 100 parts of Tanac (Note 1) and 327 parts of Plaxel M (Note 2) were placed.
The mixture was heated to 100 ° C. and stirred while blowing nitrogen.
Further, 0.06 part of tetra-n-butoxytitanium (Note 3) was added and reacted at 170 ° C. for 4 hours.
Then cooled to 80 ° C,
95 parts of KBE-9007 (Note 4) was added dropwise over 1 hour.
At this time, the temperature of the reaction product in the flask was controlled so as not to exceed 80 ° C. Subsequently, after stirring at 80 ° C. and confirming that the isocyanate value became 0, 130 parts of propylene glycol monobutyl ether was added as a solvent, and the hydrolyzable silane compound (ai) had a solid content of 80. % Hydrolyzable silane compound No. 1 One solution was obtained.

(Note 1) Tanac: trade name, manufactured by Nissei Sangyo Co., Ltd., 1,3,5-tris- (2-hydroxyethyl) isocyanurate,
(Note 2) Plaxel M: trade name, manufactured by Daicel, ε-caprolactone,
(Note 3) Tetra-n-butoxy titanium: catalyst (Note 4) KBE-9007: trade name, manufactured by Shin-Etsu Chemical Co., Ltd., 3-isocyanatopropyltriethoxysilane.

(Production Example 2) Hydrolyzable silane compound No. Production of 2 To a four-necked flask equipped with a reflux condenser, a thermometer, an air introduction tube and a stirrer, 100 parts of Tanac (Note 1) and 95 parts of N-methyl-2-pyrrolidone (NMP) as a solvent were added and stirred. did. The temperature was raised to 85 ° C. while blowing nitrogen, and the mixture was stirred for 30 minutes to confirm that the tanac was dissolved, and then cooled to 80 ° C.
Thereafter, 284 parts of KBE-9007 (Note 4) was added dropwise over 1 hour.
At this time, the temperature of the reaction product in the flask was controlled so as not to exceed 80 ° C. Subsequently, after stirring at 80 ° C. for 7 hours, 0.02 part of dibutyltin dilaurate (catalyst) was added. It was confirmed that the isocyanate value was 0, and hydrolyzable silane compound No. 1 having a solid content of 80%, which is a hydrolyzable silane compound (ai). Two solutions were obtained.

Production Example 3 Hydroxyl group-containing acrylic resin No. 1 Production of 1 31 parts of ethyl 3-ethoxypropionate was charged into a four-necked flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas inlet, and the temperature was raised to 155 ° C. under nitrogen gas flow. After reaching 155 ° C., the flow of nitrogen gas was stopped, and a monomer mixture composed of the following monomer and polymerization initiator was added dropwise over 4 hours.
42.0 parts of 4-hydroxybutyl acrylate,
20.0 parts of styrene,
20.8 parts of isobornyl acrylate,
16.2 parts 2-ethylhexyl acrylate,
1.0 part of acrylic acid, and 4.0 parts of di-tert-amyl peroxide,
Next, after aging for 2 hours while ventilating nitrogen gas at 155 ° C., the mixture is cooled to 100 ° C. and diluted with 32.5 parts of butyl acetate, whereby a hydroxyl group-containing acrylic resin having a solid content of 60% is obtained as a binder component. No. One solution was obtained. The copolymer had a weight average molecular weight of 13,000, a hydroxyl value of 164 mgKOH / g, and a glass transition temperature of -12.0 ° C.

(Production Example 4) Hydroxyl group-containing acrylic resin No. Production of 2 31 parts ethyl 3-ethoxypropionate was charged into a four-necked flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas inlet, and the temperature was raised to 155 ° C. under nitrogen gas flow. After reaching 155 ° C., the flow of nitrogen gas was stopped, and a monomer mixture composed of the following monomer and polymerization initiator was added dropwise over 4 hours.
24.0 parts 2-hydroxypropyl acrylate,
20.0 parts of styrene,
20.8 parts of isobornyl acrylate,
34.2 parts 2-ethylhexyl acrylate,
1.0 part of acrylic acid, and 4.0 parts of di-tert-amyl peroxide,
Next, after aging for 2 hours while ventilating nitrogen gas at 155 ° C., the mixture is cooled to 100 ° C. and diluted with 32.5 parts of butyl acetate, whereby a hydroxyl group-containing acrylic resin having a solid content of 60% is obtained as a binder component. No. Two solutions were obtained. The copolymer had a weight average molecular weight of 13,000, a hydroxyl value of 103 mgKOH / g, and a glass transition temperature of -11.0 ° C.

(Production Example 5) Production of silica particles (A-1) whose surfaces are modified
In a separable flask equipped with a reflux condenser, thermometer and stirrer,
Colloidal silica no. 1 (Note 5) After blending 333 parts (100 parts solids) and 10 parts deionized water,
Hydrolyzable silane compound No. 1 obtained in Production Example 1. 1 25 parts (solid content 20 parts), hydrolyzable silane compound No. 1 4 (Note 8) After adding 5 parts and performing a dehydration condensation reaction with stirring at 80 ° C. for 2 hours, 0.03 part of tetra-n-butylammonium fluoride was added and allowed to react with stirring for another hour. It was. After completion of the reaction, the volatile component was distilled off under reduced pressure, and 350 parts of ethyl 3-ethoxypropionate was added and azeotropically distilled to replace the solvent with ethyl 3-ethoxypropionate, and the surface was modified. A 30% solid solution of silica particles (A-1) was obtained.

(Production Examples 6 to 17) Production of silica particles (A-2) to (A-13) whose surfaces are modified Production Example 5 is the same as Production Example 5 except that the composition of each component is as shown in Table 1. In the same manner, silica particle (A-2) to (A-13) solutions in which the surface having a solid content of 30% was modified were obtained. In addition, the mixing | blending shown in Table 1 is solid content mass ratio of each component.

(Production Example 18) Production of silica particles (A-14) whose surfaces are modified
In a separable flask equipped with a reflux condenser, thermometer and stirrer,
Colloidal silica no. 1 (Note 6) 250 parts (solid content 100 parts) and propylene glycol monomethyl ether 250 parts
Subsequently, the hydrolyzable silane compound No. 1 obtained in Production Example 1. 1 25 parts (solid content 20 parts), hydrolyzable silane compound No. 1 4 (Note 8) 5 parts were added, the temperature was raised to 60 degrees with stirring, and the solvent in the reaction system was replaced by distillation under reduced pressure. Then, after performing a dehydration condensation reaction with stirring at 60 ° C. for 2 hours, 0.03 part of tetra-n-butylammonium fluoride was added, and the mixture was further reacted with stirring for 1 hour. After completion of the reaction, the volatile component was distilled off under reduced pressure, and 350 parts of ethyl 3-ethoxypropionate was added and azeotropically distilled to replace the solvent with ethyl 3-ethoxypropionate, and the surface was modified. A 30% solid solution of silica particles (A-14) was obtained.

(Production Examples 19 to 20) For comparative examples:
Production of Silica Particles (A′-1) and (A′-2) with Modified Surfaces In Production Example 5, a comparison was made in the same manner as in Production Example 5 except that the composition of each component was as shown in Table 1. The silica particle (A'-1) and (A'-2) solution by which the surface of 30% of solid content was modified was obtained. In addition, the mixing | blending shown in Table 1 is solid content mass ratio of each component.

(Note 5) Colloidal silica no. 1: PGM-ST, trade name, manufactured by Nissan Chemical Industries, Ltd., silica average primary particle size: 15 nm, silica concentration: 30% by mass, dispersion medium: propylene glycol monomethyl ether (Note 6) Colloidal silica No. 1 2: Snowtex O-40, trade name, manufactured by Nissan Chemical Industries, Ltd., silica average primary particle size: 25 nm, silica concentration: 40% by mass, dispersion medium: water (Note 7) Hydrolyzable silane compound No. 3: KBM-9659, trade name, manufactured by Shin-Etsu Chemical Co., Ltd., tris [(trimethoxysilyl) propyl] isocyanurate, active ingredient 100%
(Note 8) Hydrolyzable silane compound No. 4: KBM-13, trade name, manufactured by Shin-Etsu Chemical Co., Ltd., methyltrimethoxysilane (Note 9) Hydrolyzable silane compound No. 5: KBM-3063, trade name, manufactured by Shin-Etsu Chemical Co., Ltd., hexyltrimethoxysilane (Note 10) Hydrolyzable silane compound No. 6: KBM-3103, trade name, manufactured by Shin-Etsu Chemical Co., Ltd., decyltrimethoxysilane.

(Example 1) Coating composition No. Production of 1 Silica particles having a modified surface (A-1) 333.3 (100 parts solids),
Hydroxyl group-containing acrylic resin no. 1 116.7 parts (solid content 70 parts), and crosslinking agent No. 1 1 (Note 13) 30.0 parts (solid content 30 parts)
Was mixed with ethyl 3-ethoxypropionate so that the solid content of the coating was 40%, and the coating composition No. 1 was obtained.

(Examples 2 to 16) Coating composition No. Production of Nos. 2 to 16 In Example 1, except that the composition of each component was changed to the composition shown in the table, the coating composition No. 2-16 were obtained. In addition, the mixing | blending of the coating composition shown in Table 2 is solid content mass ratio of each component.

(Comparative Examples 1-3) Coating composition No. Production of Examples 17 to 19 In Example 1, except that the composition of each component was as shown in the table, the same as in Example 1, Comparative Paint Composition No. 17-19 were obtained. In addition, the mixing | blending of the coating composition shown in Table 2 is solid content mass ratio of each component.

≪Preparation of test plate≫
The following coating composition Nos. Viscosity of 1 to 19 with Ford Cup #No. 4 was adjusted to a viscosity of 25 seconds at 20 ° C., and a test plate was prepared as follows for each.

Electron GT-10 (trade name, thermosetting epoxy resin-based cationic electrodeposition paint manufactured by Kansai Paint Co., Ltd.) has a thickness of 20 μm on a 0.8 mm-thick dull steel sheet subjected to zinc phosphate conversion treatment. Electrodeposited as above, cured by heating at 170 ° C. for 30 minutes, and then coated with Amirac TP-65-2 (trade name, polyester / melamine resin-based automotive intermediate coating) manufactured by Kansai Paint Co., Ltd. with a film thickness of 35 μm Air spray coating was performed, and the mixture was heated and cured at 140 ° C. for 30 minutes. A solvent base coat Neoamylac US-300 (C) No. 202 (manufactured by Kansai Paint Co., Ltd., polyester / melamine resin-based automotive topcoat base paint, black paint color) was applied on the coating film so as to have a film thickness of 15 μm. And allowed to stand at 140 ° C. for 30 minutes. Thereafter, each coating composition produced and adjusted in viscosity in the above Examples and Comparative Examples was applied on the cured coating film so as to have a film thickness of 35 μm, left at room temperature for 10 minutes, and then at 140 ° C. for 20 minutes. A test plate was obtained by heating and curing. Each of the obtained test plates was allowed to stand at room temperature for 7 days, and then the following coating film performance test was performed.
The coating film performance evaluation results are shown in Table 2.

  (Note 11) Silica particles modified on the surface (A′-3): NANOBYK-3652: manufactured by BYK, trade name, linear alkyl group-modified polydimethylsiloxane-modified silica particle dispersion, medium polarity, average particle diameter 20 nm Solid content concentration 31% (silica concentration 25% by mass), for comparative example.

  (Note 12) "-" in the table could not be evaluated because the appearance of the coating film was x.

(Note 13) Crosslinking agent No. 1: Sumidur N3300, trade name, manufactured by Sumitomo Bayer Urethane Co., Ltd., isocyanurate cycloadduct of hexamethylene diisocyanate, solid content 100%,
(Note 14) Crosslinking agent No. 2: Cymel 303, trade name, manufactured by Nippon Cytec Industry, methylated melamine resin, solid content 100%.

  (Note 15) NACURE 5543: trade name, manufactured by KING INDUSTRIES, dodecylbenzenesulfonic acid amine salt, solid content 35%, catalyst.

<Coating performance>
(Note 16) Finishability:
About each test board, the finish was evaluated by the following external appearance (visual evaluation) and glossiness measurement.
<Appearance (visual)>
Each test plate was visually observed to confirm whether the coating film had white turbidity (transparency) and distorted skin, and evaluated according to the following criteria.
○: White turbidity and yuzu skin are not recognized in the coating film ×: White turbidity or yuzu skin is recognized in the coating film <Glossiness>
The glossiness of each coated surface was measured according to the specular glossiness (20 degrees) of JIS K5600-4-7 (1999) of each test plate. As a guide, if the 20-degree gloss value is 86 or more, the finished appearance (gloss) is good.

(Note 17) Scratch resistance:
The 20-degree specular reflectance (20 ° gloss value) of the test plate after the vehicle with the test plate attached to the roof with water resistant tape made by Nichiban Co. The glossiness after the test with respect to the 20 ° gloss value before the test was determined as the gloss retention (%) and evaluated according to the following criteria. The higher the gloss retention, the better the scratch resistance. As the car washer, “PO20 FWRC” manufactured by Yasui Industry Co., Ltd. was used.
○: Gloss retention 90% or more Δ: Gloss retention 80% or more and less than 90% ×: Gloss retention 80% or less.

Claims (9)

As a silica particle (A) whose surface is modified with a hydrolyzable silane compound (a) and a binder component (B) , a hydroxyl group-containing acrylic resin (Bi-1) and a crosslinking agent (B-ii) are contained. The coating composition is a polyisocyanate compound (B-ii-1) and / or a melamine resin (Bii-2) ,
The hydrolyzable silane compound (a) is a compound represented by the following general formula (III) and / or a compound represented by the following general formula (IV)

[In formula (III), R ⁵ is the same or different and represents a divalent hydrocarbon group having 2 to 11 carbon atoms. At least one of R ^a , R ^b and R ^c represents a halogen atom, a hydroxy group, an alkoxy group or an aryloxy group, and the remainder represents a hydrogen atom, an alkyl group or an aryl group. ]

[In formula (IV), R ⁶ is the same or different and represents a divalent hydrocarbon group having 2 to 11 carbon atoms. m is the same or different and represents an integer of 0 to 5. R ^a , R ^b and R ^c are the same as described above. And a hydrolyzable silane compound (ai) having an isocyanurate ring structure, and the following general formula (II)

[In the formula (II), R ⁴ represents a monovalent hydrocarbon group having 1 to 18 carbon atoms. R ^a , R ^b and R ^c are the same as described above . ] The coating composition characterized by including the hydrolysable silane compound (a-ii) which does not have the isocyanurate ring structure represented by these. The compound represented by the general formula (IV) is obtained by reacting a compound represented by the following general formula (V) with a compound represented by the following general formula (VII), and / or It is a compound obtained by reacting a compound represented by the following general formula (V), a compound represented by the following general formula (VI), and a compound represented by the following general formula (VII). The coating composition according to claim 1, wherein

[In formula (V), R ⁶ is the same or different and represents a divalent hydrocarbon group having 2 to 11 carbon atoms. ]

[In the formula (VI), Z represents a divalent saturated hydrocarbon group having 2 to 14 carbon atoms. ]

[In Formula (VII), R ⁷ represents a divalent hydrocarbon group having 1 to 4 carbon atoms. At least one of R ^a , R ^b and R ^c represents a halogen atom, a hydroxy group, an alkoxy group or an aryloxy group, and the remainder represents a hydrogen atom, an alkyl group or an aryl group. ] The content ratio of the hydrolyzable silane compound (ai) to the hydrolyzable silane compound (a-ii) is such that hydrolyzable silane compound (ai) / hydrolyzable silane compound (a-ii) = 0. It is 05-5.0 (mass ratio), The coating composition of Claim 1 or 2 . The coating composition according to any one of claims 1 to 3 , wherein the surface-modified silica particles (A) are obtained by reacting silica fine particles (s) with a hydrolyzable silane compound (a). object. The coating composition according to any one of claims 1 to 4 , wherein an average primary particle diameter of the silica fine particles (s) is 1 to 50 nm. Solids loading of the hydrolyzable silane compound (a) is silica fine particles (s) 100 parts by weight based on to either one of claims 4 or 5, characterized in that a 1 to 55 parts by weight The coating composition as described. Solids content of the surface-modified silica particles (A) is, relative to the total resin solids of the binder component (B), any of the claims 1-6, characterized in that it contains 1 to 200 wt% The coating composition according to claim 1. The coating composition according to any one of claims 1 to 7 , which is a coating composition for topcoat clear topcoat. Method for producing a coated article obtained by coating a coating composition according to any one of claims 1-7.